CN1946767A - Endless tubular polyimide film - Google Patents

Abstract

The present invention provides a simple, efficient, and economical method for producing high-quality non-conductive or semi-conductive endless (no connecting seam) tubular polyimide membranes. Specifically, the present invention relates to a non-conductive or semi-conductive endless tubular polyimide film and a manufacturing method thereof, wherein the non-conductive or semi-conductive endless tubular polyimide film is made of polyimide Composed of amines and dispersed with a specified amount of carbon black as needed, the polyimide is composed of 15-55 mol% of asymmetric aromatic tetracarboxylic acid components and 85-45 mol% of symmetrical aromatic tetracarboxylic acid components. It consists of two or more types of aromatic tetracarboxylic acid components and aromatic diamine components.

Description

Endless Tubular Polyimide Membrane

technical field

The present invention relates to improved non-conductive or semi-conductive endless tubular polyimide membranes and methods of making the same. A semiconductive endless tubular polyimide film is used, for example, as an electrophotographic intermediate transfer belt used in a color printer, a color copier, and the like.

Background technique

A nonconductive tubular polyimide film is generally processed into a belt shape, and is known to be used, for example, as a conveyor belt for heating articles or as an electrophotographic fixing belt.

Semi-conductive tubular polyimide film, which is made by mixing and dispersing conductive carbon black in non-conductive tubular polyimide film, for example, as an intermediate copying tape for copiers, printers, fax machines and printing machines to use.

As a method for producing these non-conductive and semi-conductive tubular polyimide films, there is known a method in which a predetermined molding material is once formed into a flat film, and then both ends of the film are connected to be processed into a tubular shape. method, and a method of one-time forming into an endless tubular membrane by centrifugal injection molding. In addition, for example, the applicant of the present application has also described in Japanese Unexamined Patent Application Publication No. 2000-263568 a method of performing such centrifugal injection molding without substantially centrifugal force to perform molding.

As a raw material for forming these tubular polyimide films, polyamic acid (or polyamic acid) with a high molecular weight (number average molecular weight is usually about 10,000 to 30,000) is generally used as a polymer precursor of polyimide. acid) solution.

The above-mentioned polyamic acid solution, specifically, for example, 1,2,4,5-benzenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3 Aromatic tetracarboxylic dianhydrides such as ', 4,4'-benzophenone tetracarboxylic dianhydride and 2,3,6,7-naphthalene tetracarboxylic dianhydride, in which acid anhydride groups are bonded at point-symmetrical positions With aromatic diamines such as p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, etc., in equimolar amounts, in organic polar solvents, without Manufactured by polycondensation reaction at low temperature at which imidization occurs.

The production method of polyimide film usually adopts three processes: firstly, the polyamic acid solution as the forming raw material is produced, then the polyamic acid solution is formed into a polyamic acid film, and finally imidized to obtain polyimide membrane.

However, since the above-mentioned polyamic acid solution obtained by the above-mentioned molding method has a pot life, there is a disadvantage that partial gelation tends to gradually occur during storage. The higher the temperature, the easier the gelation is, and it progresses over time even at low temperatures, and even a very small amount of gelation will adversely affect the physical properties of the polyimide film as the final product. Of course, it also causes deterioration of planarity. Especially in the film in which the conductive carbon black is mixed, the variability in electrical resistance is increased.

In addition, the solubility of polyamic acid resins in organic polar solvents is limited, and there is a disadvantage that high concentrations cannot be achieved (at least 25% by weight as a non-volatile matter concentration in a solution).

In addition, when carbon black is added to the polyamic acid solution, the viscosity will greatly increase, and it may become difficult to disperse the carbon black by the impact force between balls in a disperser such as a ball mill. Generally, in order to uniformly disperse carbon black in a polyamic acid solution, pulverization of carbon black by a disperser must be accompanied by an interfacial phenomenon called "wetting" of disassembled carbon black by a solvent. Therefore, a method of uniformly dispersing carbon black by adding a large amount of organic polar solvent is adopted. However, as a result, only a low-concentration solution having a nonvolatile matter concentration of 16% by weight or less can be obtained for a master compound solution containing a high concentration of carbon black.

Moreover, the low-concentration polyamic acid solution has the following disadvantages: it is difficult to form a thick film at one time, and while requiring a large amount of solvent, it takes a long time to evaporate and remove the solvent.

In addition, since three steps are required as described above, there is room for improvement in the time and cost required for the entire process from the viewpoint of efficiency and economy.

However, JP-A-10-182820 describes a molding method using a polyimide precursor composition containing an aromatic tetracarboxylic acid component and an aromatic diamine component Roughly equimolar mixed monomers are the main components, and the aromatic tetracarboxylic acid component is mainly composed of asymmetric aromatic tetracarboxylic acid or its ester (specifically, 2,3,3',4'- Biphenyltetracarboxylic acid or its ester is 60 mol% or more). In addition, Japanese Patent Application Laid-Open No. 10-182820 discloses that the polyimide precursor composition is coated and cast on a glass plate, and heated (increasing the temperature stepwise between 80°C and 350°C) to form a polyimide precursor composition. In the imide film method, silver powder, copper powder, carbon black, etc. can be mixed and used as a conductive paste.

However, when the semiconductive polyimide film obtained by the above-mentioned forming method is used in an electrophotographic intermediate transfer tape used in a color printer, a color copier, etc. that require high precision in recent years, the resistance There is room for further improvement.

Contents of the invention

In view of the problems of the above-mentioned prior art, the purpose of the present invention is to provide a high-quality non-conductive or semi-conductive endless (no connection seam) tubular polyimide membrane, and to provide a simple and efficient , and economically manufacture the membrane.

The inventors of the present invention conducted intensive studies to solve the above-mentioned problems, and as a result, found that an aromatic compound composed of a specific amount of asymmetric aromatic tetracarboxylic acid or its ester and a specific amount of symmetrical aromatic tetracarboxylic acid or its ester The tetracarboxylic acid component and the aromatic diamine component are mixed in an approximately equimolar amount to form a mixed solution that is substantially in a monomer state. The mixed solution is formed into a tube by rotational molding, and heat-treated to form the imide Thus, high-quality endless tubular polyimide membranes can be produced.

That is, the present invention provides the following nonconductive or semiconductive endless tubular polyimide film.

(1) An endless tubular polyimide film, characterized in that,

Composed of polyimide, the polyimide is a mixture of 15 to 55 mol% of asymmetric aromatic tetracarboxylic acid components and 85 to 45 mol% of symmetrical aromatic tetracarboxylic acid components. Formed from aromatic tetracarboxylic acid components and aromatic diamine components,

Its yield strength (σ _Y ) is at least 120 MPa, and the ratio of breaking strength to yield strength (σ _cr /σ _Y ) is at least 1.10.

(2) A semi-conductive endless tubular polyimide film, characterized in that it is composed of 15-55 mol% of asymmetric aromatic tetracarboxylic acid components and 85-45 mol% of symmetrical aromatic tetracarboxylic acid components. Carbon black is dispersed in a polyimide composed of two or more aromatic tetracarboxylic acid components and an aromatic diamine component, and its surface resistivity is 10 ³ to 10 ¹⁵ Ω/□.

(3) The semiconductive endless tubular polyimide film as described in (2), wherein the standard deviation of the logarithmic conversion value of the surface resistivity is within 0.2, and the standard deviation of the logarithmic conversion value of the volume resistivity is The deviation is within 0.2, and the difference between the logarithmic conversion value of the surface resistivity and the logarithmic conversion value of the back surface resistivity is within 0.4.

The present invention has the characteristics described above, and more specifically includes the following first to fourth inventions.

A. The first invention

The present inventors have found that the aromatic tetracarboxylic acid component composed of a specific amount of asymmetric aromatic tetracarboxylic acid or its ester and a specific amount of symmetrical aromatic tetracarboxylic acid or its ester, and aromatic diamine Components are mixed in approximately equimolar amounts in a mixed solution that is substantially in a monomer state, and a specific amount of carbon black is dispersed, and the formed semiconductive polyimide precursor composition is formed by a rotational molding method. The tubular product is heat-treated to imidize, whereby a high-quality semiconductive endless tubular polyimide film can be produced.

Based on this finding, the present inventors conducted further studies and completed the present invention (hereinafter also referred to as "first invention").

That is, the first invention provides the following nonconductive or semiconductive endless tubular polyimide film and its manufacturing method.

(4) A method for producing an endless tubular polyimide film, characterized in that 15 to 55 mole percent of an asymmetric aromatic tetracarboxylic acid or its ester and 85 to 55 mole percent of a symmetrical aromatic tetracarboxylic acid or its ester 45 mol% aromatic tetracarboxylic acid component and aromatic diamine component are mixed in approximately equimolar amounts to form a mixed solution that is substantially in a monomer state, and is formed into a tube by rotational molding, and heat-treated. imidization.

(5) a kind of manufacture method of semiconductive endless tubular polyimide film, it is characterized in that, by asymmetric aromatic tetracarboxylic acid or its ester 15～55 mol% and symmetrical aromatic tetracarboxylic acid or In a mixed solution in which the aromatic tetracarboxylic acid component and the aromatic diamine component composed of 85 to 45 mol% of its ester are mixed in an approximately equimolar amount, which is substantially in a monomeric state, relative to the aromatic tetracarboxylic acid component and The total amount of aromatic diamine components is 100 parts by weight, 1 to 35 parts by weight of carbon black are dispersed, and the formed semiconductive monomer mixed solution is formed into a tube by rotational molding, and heat-treated. change.

(6) A semiconductive endless tubular polyimide film for an electrophotographic intermediate transfer belt produced by the production method described in (5).

B. Second invention

In addition, the inventors of the present invention conducted intensive studies to solve the above-mentioned problems, and found that heat treatment of the aromatic tetracarboxylic acid component and the aromatic diamine component substantially causes a part of the polycondensation reaction to form an oligomer containing an aromatic amic acid. (Aromatic amic acid having a number-average molecular weight of about 1000 to 7000) mixed solution, after mixing conductive carbon black in the mixed solution, performing rotational molding, and then performing imidization treatment, thus it is possible to obtain Semiconducting endless tubular polyimide film with homogeneous resistivity. Based on this finding, the present inventors further developed the present invention (hereinafter also referred to as "the second invention").

That is, the second invention provides the following semiconductive aromatic amic acid composition and its manufacturing method, and a semiconductive endless tubular polyimide film using the semiconductive aromatic amic acid composition and its manufacturing method.

(7) A semiconductive aromatic amic acid composition, characterized in that it contains aromatic amides obtained by polycondensation reaction of two or more aromatic tetracarboxylic acid components and aromatic diamines in approximately equimolar amounts Acid oligomers, carbon black and organic polar solvents.

(8) The semiconductive aromatic amic acid composition as described in (7), wherein the above-mentioned aromatic amic acid oligomer is composed of two or more aromatic tetracarboxylic dianhydrides and aromatic dicarboxylic acid dianhydrides. Aromatic amic acid oligomers obtained by polycondensation reaction of amines in approximately equimolar amounts in organic polar solvents at a temperature below about 80°C.

(9) The semiconductive aromatic amic acid composition as described in (8), it is characterized in that, more than two kinds of aromatic tetracarboxylic dianhydrides are made of asymmetric aromatic tetracarboxylic dianhydrides 15～ A mixture of 55% by mole and 85-45% by mole of symmetrical aromatic tetracarboxylic dianhydride.

(10) The semiconductive aromatic amic acid composition as described in (7), wherein the above-mentioned aromatic amic acid oligomer is composed of two or more aromatic tetracarboxylic diesters and aromatic dicarboxylic acid diesters. An aromatic amic acid oligomer obtained by polycondensation reaction of amine in an organic polar solvent at a temperature of about 90-120° C. in approximately equimolar amounts.

(11) The semiconductive aromatic amic acid composition as described in (10), it is characterized in that, more than two kinds of aromatic tetracarboxylic acid diesters are made of asymmetric aromatic tetracarboxylic acid diesters 15～ A mixture of 55% by mole and 85-45% by mole of symmetrical aromatic tetracarboxylic acid diester.

(12) The semiconductive aromatic amic acid composition according to (7), wherein the aromatic amic acid oligomer has a number average molecular weight of about 1,000 to 7,000.

(13) The semiconductive aromatic amic acid composition as described in (7), wherein the compounding amount of carbon black is 3 ~30 parts by weight.

(14) A method for producing a semiconductive endless tubular polyimide film, comprising subjecting the semiconductive aromatic amic acid composition described in (7) to rotational molding and heat treatment.

(15) A semiconductive endless tubular polyimide film for an electrophotographic intermediate transfer belt produced by the production method described in (14).

(16) A method for producing a semiconductive aromatic amic acid composition, characterized in that, in an organic polar solvent, two or more aromatic tetracarboxylic acid components and an aromatic diamine are prepared in approximately equimolar amounts. A partial polycondensation reaction forms an aromatic amic acid oligomer solution, and the aromatic amic acid oligomer solution is uniformly mixed with conductive carbon black powder.

C. The third invention

The inventors of the present invention conducted intensive research to solve the above-mentioned problems, and as a result, found that two or more kinds of aromatic tetracarboxylic acid diesters and aromatic diamines were dissolved in approximately equimolar amounts in organic polar solvents to form nylon salt-type monomers. Solution, a mixed solution obtained by mixing a predetermined high molecular weight polyimide precursor solution or a high molecular weight polyamideimide solution in the nylon salt type monomer solution, is excellent in the dispersion stability of carbon black . Furthermore, it has been found that by rotational molding using a semiconductive polyimide-based precursor composition obtained by uniformly mixing the above-mentioned mixed solution and carbon black, followed by imidization treatment, a semiconductive polyimide having uniform resistivity can be obtained. Endless tubular polyimide-based membrane. The inventors of the present invention completed the present invention (hereinafter also referred to as "the third invention") through further development.

That is, the third invention provides the following semiconductive polyimide precursor composition and its production method, and semiconductive endless tubular polyimide using the semiconductive polyimide precursor composition Membranes and methods for their manufacture.

(17) A semiconductive polyimide precursor composition, characterized in that two or more aromatic tetracarboxylic acid diesters and aromatic diamines are dissolved in approximately equimolar amounts in organic polar A high molecular weight polyimide precursor solution or a high molecular weight polyamideimide solution is mixed with a nylon salt-type monomer solution formed in a solvent to prepare a mixed solution, and carbon black is uniformly dispersed in the mixed solution.

(18) The semiconductive polyimide precursor composition as described in (17), wherein two or more aromatic tetracarboxylic diesters are made of asymmetric aromatic tetracarboxylic A mixture composed of 10-55 mole % of ester and 90-45 mole % of symmetrical aromatic tetracarboxylic acid diester.

(19) The semiconductive polyimide precursor composition as claimed in claim (17), wherein, more than two kinds of aromatic tetracarboxylic acid diesters are composed of asymmetric 2,3 , 3',4'-biphenyl tetracarboxylic acid diester 10-55 mole % and symmetrical 3,3',4,4'-biphenyl tetracarboxylic acid diester 90-45 mole % mixture.

(20) The semiconductive polyimide precursor composition as described in (17), wherein the polyimide precursor solution of high molecular weight is a polyamic acid solution with a number average molecular weight of more than 10000, The high-molecular-weight polyamide-imide solution is a polyamide-imide solution having a number average molecular weight of 10,000 or more.

(21) semiconductive polyimide precursor composition as claimed in claim (20), it is characterized in that, above-mentioned number-average molecular weight is the polyamic acid solution more than 10000, by biphenyltetracarboxylic dianhydride It is produced by reacting with diaminodiphenyl ether in approximately equimolar amounts in an organic polar solvent.

(22) The semiconductive polyimide precursor composition as described in (20), wherein the polyamide-imide solution having a number-average molecular weight of more than 10,000 consists of trimellitic anhydride and benzophenone It is produced by reacting an acid anhydride formed of tetracarboxylic dianhydride and an aromatic isocyanate in an organic polar solvent in approximately equimolar amounts.

(23) A method for producing a semiconductive endless tubular polyimide film, comprising forming the semiconductive polyimide precursor composition described in (17) into a tubular shape by rotational molding. The product is subjected to heat treatment and imidization.

(24) A semiconductive endless tubular polyimide having a surface resistivity of 10 ⁷ to 10 ¹⁴ Ω/□ produced by the production method described in (23) and used for an electrophotographic intermediate transfer tape membrane.

(25) A method for producing a semiconductive polyimide precursor composition, characterized in that two or more aromatic tetracarboxylic acid diesters and aromatic diamines are dissolved in approximately equimolar amounts in Mix high molecular weight polyimide precursor solution or high molecular weight polyamideimide solution in the nylon salt type monomer solution formed in organic polar solvent to prepare a mixed solution, and disperse carbon black evenly in the mixed solution. in solution.

D. The fourth invention

The inventors of the present invention conducted intensive studies to solve the above-mentioned problems, and as a result, found that in a carbon black dispersion obtained by uniformly dispersing carbon black in an organic polar solvent, aromatic tetracarboxylic acid diester and An aromatic diamine can thereby prepare a semiconductive high-concentration polyimide precursor composition excellent in dispersibility of carbon black. Furthermore, it was found that a semiconductive endless tubular polyimide film having a uniform resistivity can be obtained by rotational molding using a semiconductive high-concentration polyimide precursor composition, followed by imidization treatment. The present inventors completed the present invention (hereinafter also referred to as "the fourth invention") through further development

That is, the fourth invention provides the following semiconductive high-concentration polyimide precursor composition, its production method, and semiconductive endless tubular polyimide using the semiconductive high-concentration polyimide precursor composition. Imine film and method for its manufacture.

(26) A method for preparing a semiconductive high-concentration polyimide precursor composition, characterized in that, in a carbon black dispersion formed by uniformly dispersing carbon black in an organic polar solvent, the The molar amount dissolves aromatic tetracarboxylic acid diester and aromatic diamine.

(27) The manufacture method of the semiconductive high-concentration polyimide precursor composition as described in (26), it is characterized in that, aromatic tetracarboxylic acid diester is made of asymmetric aromatic tetracarboxylic acid di A mixture composed of 10-55 mole % of ester and 90-45 mole % of symmetrical aromatic tetracarboxylic acid diester.

(28) The manufacture method of the semiconductive high-concentration polyimide precursor composition as described in (26), it is characterized in that, aromatic tetracarboxylic acid diester is made of asymmetric 2,3,3 A mixture composed of 10-55 mole % of ', 4'-biphenyl tetracarboxylic acid diester and 90-45 mole % of symmetrical 3,3',4,4'-biphenyl tetracarboxylic acid diester.

(29) The method for producing a semiconductive high-concentration polyimide precursor composition as described in (26), wherein the total amount of aromatic tetracarboxylic acid diester and aromatic diamine is 100 wt. parts, carbon black is about 5 to 35 parts by weight.

(30) A semiconductive high-concentration polyimide precursor composition produced by the production method described in (26).

(31) A method for producing a semiconductive endless tubular polyimide film, characterized in that the semiconductive high-concentration polyimide precursor composition described in (30) is formed into a tubular shape by rotational molding The product is subjected to heat treatment and imidization.

(32) A semiconductive endless tubular polyimide film for an electrophotographic intermediate transfer belt, produced by the production method described in (31), having a surface resistivity of 10 ⁷ to 10 ¹⁴ Ω/□ .

Detailed ways

Hereinafter, the present invention will be described in detail by dividing it into "A. First invention", "B. Second invention", "C. Third invention" and "D. Fourth invention".

A. The first invention

A-1. Endless tubular polyimide membrane

The endless tubular polyimide film (hereinafter also referred to as "tubular PI film") of the present invention uses a specific aromatic tetracarboxylic acid component and an aromatic diamine component as molding materials. Specifically, the non-conductive tubular PI film of the present invention uses specific aromatic tetracarboxylic acid components and aromatic diamine components as molding materials. In addition, the semiconductive tubular PI film of the present invention has , In order to impart conductivity, a predetermined amount of carbon black (hereinafter also referred to as "CB") is used as a raw material.

Aromatic tetracarboxylic acid component

As the aromatic tetracarboxylic acid component of the molding raw material, an asymmetric aromatic tetracarboxylic acid component (at least one of an asymmetric aromatic tetracarboxylic acid or its ester) and a symmetrical aromatic tetracarboxylic acid component are used. (at least one of symmetrical aromatic tetracarboxylic acid or its ester).

The so-called asymmetric aromatic tetracarboxylic acids include those in which four carboxyl groups are bonded to asymmetric positions on a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring). Compounds, or on compounds where two single-ring aromatic rings (benzene rings) are cross-linked with -CO-, -CH ₂ -, -SO ₂ -, etc. or single bonds, and 4 carboxyl groups are bonded to asymmetric positions compound of.

Specific examples of asymmetric aromatic tetracarboxylic acids include 1,2,3,4-benzenetetracarboxylic acid, 1,2,6,7-naphthalene tetracarboxylic acid, 2,3,3',4 '-Biphenyl tetracarboxylic acid, 2,3,3',4'-benzophenone tetracarboxylic acid, 2,3,3',4'-diphenyl ether tetracarboxylic acid, 2,3,3', 4'-diphenylmethane tetracarboxylic acid, 2,3,3',4'-diphenylsulfone tetracarboxylic acid, etc.

As the asymmetric aromatic tetracarboxylic acid ester used in the present invention, there can be mentioned diesters (half esters) of the above-mentioned asymmetric aromatic tetracarboxylic acids, specifically, the above-mentioned asymmetric tetracarboxylic acid A compound in which 2 carboxyl groups of the 4 carboxylic acids are esterified and one of the 2 adjacent carboxyl groups on the aromatic ring is esterified.

As 2 esters among the above-mentioned asymmetrical aromatic tetracarboxylic acid diesters, two lower alkyl esters can be mentioned, preferably two C _1-3 alkyl esters such as dimethyl esters, diethyl esters, and dipropyl esters ( especially dimethyl esters).

Among the above-mentioned asymmetric aromatic tetracarboxylic acid diesters, dimethyl 2,3,3',4'-biphenyltetracarboxylate, 2,3,3',4'-biphenyltetracarboxylic acid Acid diethyl ester, particularly preferably use dimethyl 2,3,3',4'-biphenyltetracarboxylate.

In addition, the said asymmetric aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, it can be easily produced by known methods such as reacting 1 part of corresponding asymmetric aromatic tetracarboxylic dianhydride with 2 parts (molar ratio) of corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.) . By such a method, an acid anhydride as a raw material reacts with an alcohol to open a ring, and a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons on the aromatic ring can be produced.

Symmetrical aromatic tetracarboxylic acids include compounds in which four carboxyl groups are bonded to point-symmetrical positions on a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring), Or on a compound where two single-ring aromatic rings (benzene ring, etc.) are cross-linked by -CO-, -O-, -CH ₂ -, -SO ₂ -, etc. or a single bond, 4 carboxyl groups are bonded to the point symmetrically compound in position.

Specific examples of symmetrical aromatic tetracarboxylic acids include 1,2,4,5-benzenetetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 3,3', 4,4' -Biphenyl tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-diphenyl ether tetracarboxylic acid, 3,3',4,4 '-Diphenylmethane tetracarboxylic acid, 3,3',4,4'-diphenylsulfone tetracarboxylic acid, etc.

As the symmetrical aromatic tetracarboxylic acid ester used in the present invention, can enumerate the diester (half ester) of above-mentioned symmetrical aromatic tetracarboxylic acid, specifically, can enumerate among the above-mentioned symmetrical tetracarboxylic acid 4 A compound in which two carboxyl groups in a carboxylic acid are esterified and one of the two adjacent carboxyl groups on the aromatic ring is esterified.

As two esters among the above-mentioned symmetrical aromatic tetracarboxylic acid diesters, di-lower alkyl esters can be mentioned, preferably C _1-3 alkyl esters such as dimethyl ester, diethyl ester, and dipropyl ester (especially dimethyl ester).

Among the above-mentioned symmetrical aromatic carboxylic acid diesters, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, Ethyl ester, dimethyl 2,3,5,6-benzenetetracarboxylate, and dimethyl 3,3',4,4'-biphenyltetracarboxylate are particularly preferably used.

In addition, the said symmetrical aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, it can be easily produced by a known method such as reacting 1 part of the corresponding symmetrical aromatic tetracarboxylic dianhydride with 2 parts (molar ratio) of the corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.). By such a method, an acid anhydride as a raw material reacts with an alcohol to open a ring, and a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons on the aromatic ring can be produced.

The mixing ratio of the asymmetric and symmetric aromatic tetracarboxylic acids or their esters is specifically defined to be about 15 to 55 mol% (preferably 20 to 50 mol%) of the asymmetric aromatic tetracarboxylic acids or their esters, The proportion of symmetrical aromatic tetracarboxylic acid or its ester is about 85 to 45 mol % (preferably 80 to 50 mol %). In particular, the asymmetric aromatic tetracarboxylic diester is preferably used in an amount of about 20 to 50 mol%, and the symmetrical aromatic tetracarboxylic diester is used in an amount of about 80 to 50 mol%.

The reason why it is necessary to mix the above-mentioned asymmetric and symmetric aromatic tetracarboxylic acid components is as follows. When only symmetrical aromatic tetracarboxylic acid or its ester is used, since the polyimide film exhibits crystallinity, the film is pulverized during the heat treatment and cannot be formed into a film. On the other hand, when only asymmetric aromatic tetracarboxylic acid or its ester is used, although it can be formed into an endless tubular PI film, the yield strength and elastic modulus of the obtained film are weak, and when used as a rotating belt, not only Responsiveness during driving is poor, and problems such as elongation of the rotary belt may occur in the initial stage.

On the other hand, if an aromatic tetracarboxylic acid or its ester having the above-mentioned mixing ratio is used, extremely high film forming properties (formability) can be obtained, and semiconductive materials having high yield strength and high modulus of elasticity can be obtained. Endless tubular PI membrane.

In addition, the applicant believes that by adding an asymmetric aromatic tetracarboxylic acid or its ester, the polyamic acid molecules can be bent to generate flexibility.

Moreover, the coexistence effect of the said symmetric and asymmetric aromatic tetracarboxylic acid or its ester can be exhibited most effectively when the mixing ratio of both is as shown above.

Aromatic diamine component

Examples of aromatic diamine components include compounds having two amino groups on one aromatic ring (benzene ring, etc.), or compounds with two or more aromatic rings (benzene rings, etc.) represented by -O-, -S-, -CO -, -CH ₂ -, -SO-, -SO ₂ -, etc., or a compound having two amino groups cross-linked by a single bond. Specifically, for example, p-phenylene diamine, o-phenylene diamine, m-phenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylcarbonyl, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, etc. Among them, 4,4'-diaminodiphenyl ether is particularly preferable. This is because by using these aromatic diamine components, the reaction can proceed more smoothly, and at the same time, a tougher film with higher heat resistance can be produced.

organic polar solvent

As the organic polar solvent used in the mixed solution in a monomeric state substantially, an aprotic organic polar solvent is preferred, for example, N-methyl-2-pyrrolidone (hereinafter referred to as "NMP"), N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl- 2-imidazolinone, etc. It may be one of them or a mixed solution of two or more. NMP is particularly preferred. The amount of the organic polar solvent used is about 65 to 300 parts by weight (preferably about 80 to 230 parts by weight, more preferably 100 to 200 parts by weight or so).

Carbon black (CB)

When producing the semiconductive tubular PI film of the present invention, CB powder is used in addition to the above-mentioned components to impart resistance characteristics. The reason for using carbon black is that it is superior in mixing dispersibility and stability (time-dependent change after mixing and dispersing) when mixed with the prepared monomer mixed solution compared to other commonly known conductive materials of metals and metal oxides. , and has no adverse effect on the polycondensation reaction.

The CB powder has a variety of physical properties (resistance, volatile matter, specific surface area, particle size, pH value, DBP oil absorption) according to its manufacturing raw materials (natural gas, acetylene gas, tar, etc.) quantity, etc.). Those with well-developed structure and high conductivity index (this is mostly CB powder made of acetylene gas as raw material), although the specified resistance can be obtained with a relatively small amount of filling, but the mixing dispersibility is not good. Although the conductivity index is not high, the oxidized CB powder with low pH value and the CB powder containing more volatile matter need more filling to achieve the specified resistance, but the mixing dispersibility and storage stability are excellent. Also it is easy to obtain strips with homogeneous electrical resistance.

The conductive CB powder usually has an average particle diameter of about 15 to 65 nm, and in particular, when used in an electrophotographic intermediate transfer tape used in a color printer, a color copier, etc., the average particle diameter is preferably 20 nm. ~40nm or so.

For example, channel black, oxidized furnace black, etc. are mentioned. Specifically, Special Black 4 (pH 3, volatile content 14%, particle diameter 25 nm) and Special Black 5 (pH 3, volatile content 15%, particle diameter 20 nm) manufactured by Degusa Co., Ltd. can be exemplified.

The amount of CB powder to be added is preferably 1 to 35 parts by weight relative to 100 parts by weight of the total amount of the aromatic tetracarboxylic acid component and the aromatic diamine component as the molding raw material of the mixed solution in a substantially monomeric state. about parts (preferably about 5 to 25 parts by weight).

Here, the reason why CB powder is used within the above range is to impart volume resistivity (Ω·cm) (VR) and surface resistivity (Ω/□) (SR) to the film in the semiconductive region. The lower limit is about 1 part by weight or more because it is necessary to obtain sufficient electrical conductivity; the upper limit is about 35 parts by weight or less because it exhibits lower resistance while maintaining formability and preventing film The lowering of its own physical characteristics.

Preparation of monomer mixed solution

A predetermined amount of an aromatic tetracarboxylic acid component, an aromatic diamine component, and an organic polar solvent are mixed to prepare a substantially monomeric mixed solution for molding (hereinafter also referred to as "monomer mixed solution"). The so-called non-conductive tubular PI film and semiconductive tubular PI film of the present invention are only different in the presence or absence of CB powder, and the monomer mixed solution as the forming raw material is prepared under the same conditions. The modulation order thereof is not particularly limited. The aromatic tetracarboxylic acid component used in the present invention does not substantially react with the diamine component at a low temperature (for example, 30 to 40° C. or less), unlike the case of using a highly reactive aromatic tetracarboxylic dianhydride. It is also advantageous in terms of preparing a monomer mixed solution.

The monomer mixed solution is prepared by mixing and dissolving the above-mentioned aromatic tetracarboxylic acid component and aromatic diamine component in an approximately equimolar reaction ratio in an organic polar solvent. Since these components are monomers, they are easily dissolved in organic polar solvents, and can be uniformly dissolved at a high concentration, and the obtained solution can substantially maintain the monomer state. In the present invention, the mixed solution in the monomer state is used as a molding raw material.

Here, the substantially equimolar amount means the reaction ratio at which the polycondensation reaction of the aromatic tetracarboxylic acid component and the aromatic diamine component proceeds smoothly and a predetermined high molecular weight polyimide is obtained. Substantially in a monomeric state means that all the components in the mixed solution are in a monomeric state, but a small amount of low-molecular polycondensation reaction products of an oligomer level may be contained within the range that does not adversely affect the present invention.

The amount of the organic polar solvent used is about 65 to 300 parts by weight (preferably about 80 to 230 parts by weight, more preferably 100 to 200 parts by weight or so). Since the produced mixed solution in a substantially monomeric state is easily dissolved in the above-mentioned organic polar solvent, there is an advantage that the amount of the solvent used can be reduced as much as possible.

Next, the preparation method of the monomer mixed solution will be illustrated.

As a first example, first, the aforementioned predetermined mol% symmetric and asymmetric aromatic tetracarboxylic acid components are mixed and dissolved in an organic polar solvent. The aromatic diamine component was added to this solution in an approximately equimolar amount relative to the aromatic tetracarboxylic acid component while stirring, and after being uniformly dissolved, a monomer mixed solution for molding was obtained.

As a second example, a solution composed of the above-mentioned predetermined amount of symmetric aromatic tetracarboxylic acid component and an aromatic diamine component approximately equimolar to it, and a solution composed of a predetermined amount of asymmetric aromatic tetracarboxylic acid component are respectively prepared. and a solution composed of approximately equimolar aromatic diamine components. These respective solutions were mixed so that the two types of aromatic tetracarboxylic acid components had a predetermined mol% to form a monomer mixed solution for molding.

As a third example, predetermined amounts of symmetrical and asymmetrical aromatic tetracarboxylic acid components and aromatic diamine components are simultaneously added to an organic polar solvent to prepare a homogeneous monomer mixed solution.

The existing polyimide acid solution can only reach 25% by weight at most, while the non-volatile matter in the monomer mixed solution of the present invention can reach a high level of about 45% by weight (especially 30-45% by weight). concentration. The "non-volatile matter concentration" used in this specification means the concentration measured by the method described in an Example. By using a high-concentration monomer mixed solution, the polycondensation reaction proceeds rapidly, and the molding time can be shortened. In addition, a thick film can be easily produced, and since the amount of solvent used is small, cost can be suppressed and evaporation and removal of the solvent can be facilitated.

In addition, within the range of no adverse effect on the effects of the present invention, imidazole compounds (2-methylimidazole, 1,2-dimethylimidazole, 2-methyl-4- Methylimidazole, 2-ethyl-4-ethylimidazole, 2-phenylimidazole), surfactants (fluorosurfactants, etc.) and other additives.

In the production of the semiconductive tubular PI film, a semiconductive monomer mixed solution in which carbon black is dispersed in the monomer mixed solution is used. The method of mixing the CB powder into the monomer mixed solution may be a known method such as stirring, and is not particularly limited. For this stirring, it is preferable to use a ball mill, so that a semiconductive monomer mixed solution for molding in which CB is uniformly dispersed can be obtained.

The amount of carbon black used is 1 to 35 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the total amount of the aromatic tetracarboxylic acid component and the aromatic diamine component, as described above.

A-2. Manufacturing method of endless tubular polyimide membrane

Next, a method for forming a tubular PI film using the monomer mixed solution or semiconductive monomer mixed solution prepared above will be described. Hereinafter, a molding method using a monomer mixed solution will be described, but a molding method using a semiconductive monomer mixed solution can also be implemented in the same manner.

The forming method employs a rotational forming method using a rotating drum. First, inject the monomer mixed solution into the inner surface of the rotating cylinder, and spread it evenly on the entire inner surface.

The method of injection-casting is, for example, in a stopped rotating cylinder, after injecting a monomer mixed solution equivalent to the final film thickness, slowly increase the rotation speed until the speed at which the centrifugal force acts, and evenly cast it by centrifugal force on the inside as a whole. Alternatively, injection-casting without the use of centrifugal force is also possible. For example, if a horizontally long slit-shaped nozzle is arranged on the inner surface of a cylinder, and the cylinder is slowly and continuously rotated, the nozzle is also rotated (at a speed faster than the rotation speed). Then, the monomer mixed solution for molding is uniformly sprayed from the nozzle to the entire inner surface of the cylinder. The cylinder is mounted on a rotating roller and can be rotated indirectly by the rotation of the roller.

The heating is indirect heating performed from the outside by arranging a heat source such as a far-infrared heater around the circumference of the cylinder. The size of the cylinder depends on the desired size of the semiconducting tubular PI film.

Heating is performed to gradually increase the temperature of the inner surface of the cylinder, at first about 100 to 190°C, preferably about 110 to 130°C (the first heating stage). The heating rate may be, for example, about 1 to 2° C./min. Maintain the above temperature for 30-120 minutes to volatilize more than half of the solvent and form a self-supporting tubular membrane. In order to imidize, it is necessary to reach a temperature above 280°C, but if it is heated at such a high temperature at the beginning, not only the polyimide will show high crystallization, which will affect the dispersion state of CB, but also exist Problems such as being unable to form a strong film. Therefore, as the first heating stage, the upper limit temperature is controlled at a maximum of about 190°C, at which temperature the polycondensation reaction is terminated, and a tough tubular PI film is obtained.

After this step is completed, next, as a second heating step, heating is performed to complete imidization, and the temperature is about 280 to 400° C. (preferably about 300 to 380° C.). At this time, it is better not to reach the temperature suddenly from the temperature in the first heating stage, but to gradually raise the temperature to reach the temperature.

In addition, the second heating stage can be carried out directly in the state where the endless tubular film is attached to the inner surface of the rotating cylinder, or the endless tubular film can be peeled off from the rotating cylinder after the end of the first heating stage to provide other methods for achieving Heating means for imidization, heating to 280-400°C. The time taken for this imidization is about 2 to 3 hours normally. Therefore, the time taken for the entire process of the first and second heating stages is usually about 4 to 7 hours.

This produces the nonconductive (or semiconductive) PI film of the present invention. The thickness of the film is not particularly limited, but is usually about 30 to 200 μm, preferably about 60 to 120 μm. In particular, when used as an electrophotographic intermediate transfer tape, it is preferably about 75 to 100 μm.

In the case of a semiconductive PI film, the semiconductivity of the film is a resistive characteristic determined by both the volume resistivity (Ω·cm) (VR) and the surface resistivity (Ω/□) (SR), This characteristic is imparted by mixing and dispersing CB powder. And the range of this resistance can basically be freely changed by the mixing amount of CB powder. Examples of the resistivity range of the film of the present invention include VR: 10 ² to 10 ¹⁴ , SR: 10 ³ to 10 ¹⁵ , and preferred ranges include VR: 10 ⁶ to 10 ¹³ and SR: 10 ⁷ ~10 ¹⁴ . These resistivity ranges can be easily achieved by using the above-mentioned compounding amount of the CB powder. In addition, the CB content in the film of the present invention is usually about 5 to 25% by weight, preferably about 8 to 20% by weight.

The semiconductive PI film of the present invention has very uniform resistivity. That is, the characteristic point of the semiconductive PI film of the present invention is that the variability of the logarithmic conversion values of the surface resistivity SR and the volume resistivity VR is small, and the standard of each logarithmic conversion value at all measurement points in the film is The deviation is within 0.2, preferably within 0.15. In addition, it has a feature that the difference between the surface resistivity (logarithmic conversion value) of the film surface and the back surface is small, and the difference is within 0.4, preferably within 0.2. Furthermore, it has a feature that the value obtained by subtracting the logarithmic conversion value LogVR of the volume resistivity from the logarithmic conversion value LogSR of the surface resistivity can be maintained at a high value of 1.0 to 3.0, preferably 1.5 to 3.0.

The semiconductive PI film of the present invention has various uses due to its excellent resistance characteristics and other functions. For example, electrophotographic intermediate transfer tapes used in color printers, color copiers, and the like are exemplified as important applications requiring charging characteristics. The required semiconductivity (resistivity) of the tape is, for example, VR of 10 ⁹ to 10 ¹² and SR of 10 ¹⁰ to 10 ¹³ , and the semiconductive endless tubular PI film of the present invention can be suitably applied.

The nonconductive or semiconductive PI film of the present invention has excellent performance as a tape, and has high yield strength (σ _Y ) and high breaking strength (σ _cr ). The yield strength (σ _Y ) is above 120 MPa, especially 120-160 MPa, and the ratio of fracture strength to yield strength (σ _cr /σ _Y ) is above 1.10, especially around 1.10-1.35.

B. Second invention

The semiconductive endless tubular polyimide film of the present invention (hereinafter also referred to as "semiconductive tubular PI film") is made of aromatic amic acid oligomers, conductive carbon black (hereinafter also referred to as "CB ”) and a semiconductive aromatic amic acid composition of an organic polar solvent, manufactured by rotational molding and amidation treatment.

B-1. Semiconductive aromatic amic acid composition

In the semiconductive aromatic amic acid composition of the present invention, in an organic polar solvent, two or more aromatic tetracarboxylic acid components and aromatic diamine components are partially polycondensed in approximately equimolar amounts to form an aromatic Amic acid oligomer (aromatic amic acid with a number average molecular weight of about 1000-7000) solution, and then uniformly mix the solution with conductive carbon black powder to prepare.

(1) Aromatic tetracarboxylic acid component

A mixture of at least one asymmetric aromatic tetracarboxylic acid derivative and at least one symmetric aromatic tetracarboxylic acid derivative is used as a molding raw material of two or more aromatic tetracarboxylic acid components.

Asymmetric Aromatic Tetracarboxylic Acid Derivatives

In the present invention, examples of the asymmetric aromatic tetracarboxylic acid derivative include an asymmetric aromatic tetracarboxylic dianhydride or an asymmetric aromatic tetracarboxylic diester (half ester).

Here, the so-called asymmetric aromatic tetracarboxylic acid includes four carboxyl groups bonded to asymmetric positions on a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring). On the compound, or on the compound where two monocyclic aromatic rings (benzene ring, etc.) are cross-linked by -CO-, -CH ₂ -, -SO ₂ -, etc. or a single bond, 4 carboxyl groups are bonded to non-point Compounds in symmetrical positions.

Specific examples of asymmetric aromatic tetracarboxylic acids include 1,2,3,4-benzenetetracarboxylic acid, 1,2,6,7-naphthalene tetracarboxylic acid, 2,3,3',4 '-Biphenyl tetracarboxylic acid, 2,3,3',4'-benzophenone tetracarboxylic acid, 2,3,3',4'-diphenyl ether tetracarboxylic acid, 2,3,3', 4'-diphenylmethane tetracarboxylic acid, 2,3,3',4'-diphenylsulfone tetracarboxylic acid, etc.

As the asymmetric aromatic tetracarboxylic dianhydride used in the present invention, the dianhydride of the above-mentioned asymmetric aromatic tetracarboxylic acid can be mentioned, and specifically, among the above-mentioned asymmetric tetracarboxylic acids, A compound in which adjacent carboxyl groups on an aromatic ring form two acid anhydrides. Among them, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 1,2,6,7-naphthalene tetracarboxylic dianhydride, etc. are preferably used, and 2,3,3',4' - biphenyltetracarboxylic dianhydride.

As the asymmetric aromatic tetracarboxylic acid diester (half ester) used in the present invention, the diester (half ester) of the above-mentioned asymmetric aromatic tetracarboxylic acid can be mentioned, specifically, the above-mentioned An asymmetric tetracarboxylic acid is a compound in which two carboxyl groups are esterified among the four carboxylic acids and one of the two adjacent carboxyl groups on the aromatic ring is esterified.

As 2 esters in the above-mentioned asymmetric aromatic tetracarboxylic acid diesters, two lower alkyl esters can be mentioned, preferably two C _1-3 alkyl esters such as dimethyl esters, diethyl esters, and dipropyl esters ( especially dimethyl esters).

Among the above-mentioned symmetrical aromatic carboxylic acid diesters, dimethyl 2,3,3',4'-biphenyltetracarboxylate, dimethyl 2,3,3',4'-biphenyltetracarboxylate, As the ethyl ester, dimethyl 2,3,3',4'-biphenyltetracarboxylate is particularly preferably used.

In addition, the said asymmetric aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, known methods such as reacting 1 part of corresponding asymmetric aromatic tetracarboxylic dianhydrides with 2 parts (molar ratio) of corresponding alcohols (lower alcohols, preferably C _1-3 alcohols, etc.) can be easily to manufacture. By such a method, a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons of an aromatic ring can be produced by reacting an acid anhydride as a raw material with an alcohol to open the ring.

Symmetrical Aromatic Tetracarboxylic Acid Derivatives

In this invention, a symmetrical aromatic tetracarboxylic dianhydride or a symmetrical aromatic tetracarboxylic diester (half ester) is mentioned as a symmetrical aromatic tetracarboxylic acid derivative.

Here, the so-called symmetrical aromatic tetracarboxylic acid includes a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring) in which four carboxyl groups are bonded at point-symmetrical positions. Compounds, or 4 carboxyl groups bonded to points on 2 monocyclic aromatic rings (benzene rings, etc.) with -CO-, -O-, -CH ₂ -, -SO ₂ -, etc. Compounds in symmetrical positions.

Specific examples of symmetrical aromatic tetracarboxylic acids include 1,2,4,5-benzenetetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 3,3', 4,4' -Biphenyl tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-diphenyl ether tetracarboxylic acid, 3,3',4,4 '-Diphenylmethane tetracarboxylic acid, 3,3',4,4'-diphenylsulfone tetracarboxylic acid, etc.

As the symmetrical aromatic tetracarboxylic dianhydride used in the present invention, the dianhydride of the above-mentioned symmetrical aromatic tetracarboxylic acid can be mentioned, specifically, among the above-mentioned symmetrical tetracarboxylic acids, adjacent A compound in which carboxyl groups form two acid anhydrides. Among them, 1,2,4,5-benzenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride are preferred, and 3,3',4,4'- Biphenyltetracarboxylic dianhydride. This is because it exerts a favorable effect on strength formation and the like of the obtained film.

As the symmetrical tetracarboxylic acid diester (half ester) used in the present invention, the diester (half ester) of the above-mentioned asymmetric aromatic tetracarboxylic acid can be mentioned, specifically, the above-mentioned symmetrical tetracarboxylic acid diester (half ester) can be mentioned Carboxylic acid A compound in which two of the four carboxyl groups are esterified and one of the two adjacent carboxyl groups on the aromatic ring is esterified.

As two esters in the above-mentioned symmetrical aromatic tetracarboxylic acid diesters, di-lower alkyl esters can be mentioned, preferably C _1-3 alkyl esters such as dimethyl ester, diethyl ester, and dipropyl ester (especially di methyl ester).

Among the above-mentioned symmetrical aromatic carboxylic acid diesters, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, Ethyl ester, dimethyl 2,3,5,6-benzenetetracarboxylate, and dimethyl 3,3',4,4'-biphenyltetracarboxylate are particularly preferably used.

In addition, the said symmetrical aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, by making 1 part of the corresponding symmetrical aromatic tetracarboxylic dianhydride and 2 parts (molar ratio) of the corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.) known methods such as reaction can be easily produced . By such a method, a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons of an aromatic ring can be produced by reacting an acid anhydride as a raw material with an alcohol to open the ring.

mixing ratio

The mixing ratio of the asymmetric and symmetric aromatic tetracarboxylic acid derivatives is specifically defined as 10 to 55 mol % (preferably 15 to 55 mol %, more preferably 20 to 55 mol %) of the asymmetric aromatic tetracarboxylic acid derivative. 50 mol%), and the symmetrical aromatic tetracarboxylic acid derivative is about 90 to 45 mol% (preferably 85 to 45 mol%, more preferably 80 to 50 mol%). In particular, it is suitable to use about 20 to 50 mol % of asymmetric aromatic tetracarboxylic dianhydride and about 80 to 50 mol % of symmetric aromatic tetracarboxylic dianhydride.

The reason why it is necessary to mix the above-mentioned symmetrical and asymmetrical aromatic tetracarboxylic acid components is as follows. When only symmetrical aromatic tetracarboxylic acid derivatives are used, since the polyimide film exhibits crystallinity, the film is pulverized during the heat treatment and cannot be formed into a film. On the other hand, when only asymmetric aromatic tetracarboxylic acid derivatives are used, although it can be formed into an endless tubular PI film, the yield strength and elastic modulus of the obtained film are weak, and when used as a rotating belt, not only in the Responsiveness during driving is poor, and problems such as elongation of the rotary belt may occur in the initial stage.

On the other hand, if an aromatic tetracarboxylic acid derivative composed of the above-mentioned mixing ratio is used, extremely high film forming properties (formability) can be obtained, and a semiconductive endless film having a high yield strength and a high modulus of elasticity can be obtained. Tubular PI membrane.

In addition, the applicant believes that by adding an asymmetric aromatic tetracarboxylic acid derivative, the polyamic acid molecule can be bent to generate flexibility.

Furthermore, the coexistence effect of the above-mentioned symmetrical and asymmetrical aromatic tetracarboxylic acid derivatives can be exhibited most effectively when the mixing ratio of the two is as shown above.

(2) Aromatic diamine

Examples of aromatic diamines include compounds having two amino groups on one aromatic ring (benzene ring, etc.), or compounds with two or more aromatic rings (benzene rings, etc.) represented by -O-, -S-, -CO- , -CH ₂ -, -SO-, -SO ₂ - or a compound having two amino groups cross-linked by a single bond. Specifically, for example, p-phenylene diamine, o-phenylene diamine, m-phenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylcarbonyl, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, etc. Among them, 4,4'-diaminodiphenyl ether is particularly preferable. This is because by using these aromatic diamine components, the reaction proceeds more smoothly and a tougher and higher heat-resistant film can be produced.

(3) Organic polar solvents

As the organic polar solvent used, preferably an aprotic organic polar solvent, for example, use N-methyl-2-pyrrolidone (hereinafter referred to as "NMP"), N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolinone, etc. One or a mixture of two or more solvents may be used. NMP is particularly preferred. The amount of the organic polar solvent used may be about 100 to 300 parts by weight (preferably about 150 to 250 parts by weight) relative to 100 parts by weight of the total amount of the aromatic tetracarboxylic acid component and the aromatic diamine component as raw materials. . Since the produced aromatic amic acid oligomer is easily dissolved in the above-mentioned organic polar solvent, there is an advantage that the amount of solvent used can be reduced as much as possible.

(4) Preparation of aromatic amic acid oligomer solution

The method of preparing an aromatic amic acid oligomer (about 1000 to 7000 in number average molecular weight) by performing a partial polycondensation reaction of the above-mentioned two or more mixed aromatic tetracarboxylic acid components and organic diamine components in an organic polar solvent is exemplified below. .

As the preparation method of the first aromatic amic acid oligomer, two or more kinds of aromatic tetracarboxylic dianhydrides and aromatic diamines are prepared in approximately equimolar amounts in an organic polar solvent at about 80°C. The aromatic amic acid oligomer (about number average molecular weight 1000-7000) can be produced by performing polycondensation reaction at the following temperature.

Specifically, about 15 to 55 mol% (preferably 20 to 50 mol%) of asymmetric aromatic tetracarboxylic dianhydride and 85 to 45 mol% (preferably 80 to 50 mol%) of symmetrical aromatic tetracarboxylic dianhydride %) The mixture composed of about 100% is provided to the polycondensation reaction. As the organic polar solvent, the ones mentioned above are used, and NMP is particularly preferred.

The reason why the reaction temperature is set at about 80° C. or lower is to suppress the imidization reaction at the time of forming the aromatic amic acid oligomer. More preferable reaction temperature is 30-70 degreeC. When reaction temperature exceeds 80 degreeC, since polyimide is easy to be formed by imidation reaction, it is unpreferable. The reaction time varies depending on the reaction temperature, but is usually about several hours to 72 hours.

In addition, any known method may be used to adjust the molecular weight of the aromatic amic acid oligomer. For example, it can be suitably carried out by the method of polymerizing aromatic tetracarboxylic acid component/aromatic diamine component at a molar ratio of 0.5 to 0.95 to form an aromatic amic acid oligomer with a predetermined molecular weight, and then adding The aromatic tetracarboxylic acid component makes the aromatic tetracarboxylic acid component/aromatic diamine component roughly equimolar (referring to Japanese Patent Publication No. 1-22290); In the equimolar reaction, a compound that inhibits polymerization such as water is allowed to coexist in a predetermined amount (see JP-A-2-3820).

As the preparation method of the second aromatic amic acid oligomer, by mixing two or more aromatic tetracarboxylic acid diesters and aromatic diamines in approximately equimolar amounts in an organic polar solvent at a temperature of 90 to 120 By carrying out the polycondensation reaction at a temperature of about °C, an aromatic amic acid oligomer (number average molecular weight of about 1000 to 7000) can be produced.

Specifically, about 15-55 mole % (preferably 20-50 mole %) of asymmetric aromatic tetracarboxylic acid diester and 85-45 mole % (preferably 80-50 mole %) of symmetrical aromatic tetracarboxylic acid diester %) The mixture composed of about 100% is provided to the polycondensation reaction. As the organic polar solvent, the ones mentioned above are used, and NMP is particularly preferred.

In order to adjust the aromatic amic acid oligomer with desired molecular weight, the reaction temperature and reaction time are closely related. Usually, the heating temperature is 90 to 120° C., but when the reaction temperature is in a high temperature range, it is preferable to shorten the reaction time in order to suppress the amount of imide formation (imidization ratio) and increase the molecular weight. In addition, in the heat treatment, the temperature may be raised gradually to a predetermined temperature, reacted at the predetermined temperature for about 1 to 3 hours, and then cooled. For example, what is necessary is just to heat up to 90-120 degreeC in about 1 hour - 4 hours, to react at this temperature for about 30 minutes - 2 hours, and to cool after that.

In the first and second preparation methods above, the substantially equimolar amount refers to a reaction ratio capable of preparing an aromatic amic acid of a predetermined oligomer grade and further obtaining the intended semiconductive tubular PI film. Moreover, when dissolving both components uniformly in an organic polar solvent, you may heat (for example, about 40-70 degreeC) as needed.

The aromatic amic acid oligomer solution can be prepared by the above-mentioned first and second preparation methods so that the number average molecular weight (Mn) thereof is about 1000 to 7000 (preferably about 3000 to 7000). The significance of being specific to this range is that if the number average molecular weight is less than 1000 (that is, monomers, dimers or so), the effect of conductive characteristics cannot be obtained, and if the number average molecular weight is more than 7000, due to the solubility of oligomers Extremely low, the solution was unusable due to gelation, etc. (for example, refer to Comparative Example B-1). In addition, the number average molecular weight can be measured by the method described in an Example, for example.

The preparation of the present invention is an aromatic amic acid oligomer having a number average molecular weight (Mn) of about 1000 to 7000, and the ratio (Mw/Mn) to the weight average molecular weight (Mw) is usually 2 or less.

The aromatic amic acid oligomer solution produced by this heat treatment may contain an aromatic amic acid oligomer as a main component, but a part thereof may further react and imidize. However, the production rate (imidization rate) of the imide body in the aromatic amic acid oligomer is 30% or less, preferably 25% or less, more preferably 20% or less. In addition, the amount of by-produced imides produced (imidation rate) can be measured, for example, by the method described in Examples.

In addition, the nonvolatile concentration in the aromatic amic acid oligomer solution can be adjusted to a high concentration of about 30 to 45% by weight. The reason why such a high non-volatile matter concentration can be prepared is that, since it is an oligomer which has not been polymerized, it is easy to dissolve in a solvent. Therefore, a thick film can be easily produced, and since the amount of solvent used is small, the cost can be suppressed, and the evaporation and removal of the solvent can be facilitated. The "non-volatile matter concentration" used in this specification means the concentration measured by the method described in Example B-1.

(5) Preparation of semiconductive aromatic amic acid composition

The thus-obtained aromatic amic acid oligomer solution and conductive CB powder were uniformly mixed to prepare a semiconductive aromatic amide composition.

The reason why CB powder is used to impart resistance characteristics is that, compared with other commonly known conductive materials such as metals or metal oxides, the mixing dispersibility and stability of mixing with the prepared monomer mixed solution (mixing dispersion) time-dependent change) is excellent, and has no adverse effect on the polycondensation reaction.

The CB powder has a variety of physical properties (resistance, volatile matter, specific surface area, particle size, pH value, DBP oil absorption) according to its manufacturing raw materials (natural gas, acetylene, tar, etc.) and manufacturing conditions (combustion conditions) wait). It is better to select a CB powder that is stable and easy to obtain without causing deviation in the desired resistance even with a small amount of mixing and dispersion.

The conductive CB powder usually has an average particle diameter of about 15 to 65 nm. Especially, when used in an electrophotographic intermediate transfer belt used in a color printer, a color copier, etc., the average particle diameter is preferably about 20 to 40 nm. .

For example, channel black, oxidized furnace black, etc. are mentioned. Specifically, Special Black 4 (pH 3, volatile content 14%, particle diameter 25 nm) and Special Black 5 (pH 3, volatile content 15%, particle diameter 20 nm) manufactured by Degusa Co., Ltd. can be exemplified.

The method of mixing the CB powder in the aromatic amic acid oligomer solution is not particularly limited as long as the CB powder is uniformly mixed and dispersed in the aromatic amic acid oligomer solution. For example, a ball mill, a wheel mixer, an ultrasonic mill, or the like can be used.

The amount of CB powder to be added is preferably about 3 to 30 parts by weight (more preferably 10 ~25 parts by weight or so).

Here, the reason why CB powder is used within the above-mentioned range is to impart volume resistivity (VR) and surface resistivity (SR) in the semiconductive region to the film. The lower limit is about 3 parts by weight or more because it is necessary to obtain sufficient electrical conductivity; the upper limit is about 30 parts by weight because it maintains formability while exhibiting lower resistance and prevents film The reduction of its own physical characteristics.

The non-volatile matter concentration in the semiconductive aromatic amic acid composition is about 30 to 45% by weight, and the concentration of CB powder in the non-volatile matter is about 3 to 25% by weight (preferably about 10 to 20% by weight) , The concentration of the nonvolatile matter derived from the aromatic amic acid oligomer is about 75 to 97% by weight (preferably 80 to 90% by weight).

In addition, imidazole compounds (2-methylimidazole, 1,2-dimethylimidazole, 2-methyl-4-methylimidazole, imidazole, 2-ethyl-4-ethylimidazole, 2-phenylimidazole), surfactants (fluorosurfactants, etc.) and other additives.

In this way, a semiconductive aromatic amic acid composition for molding in which the CB powder is uniformly dispersed can be produced.

B-2. Semiconductive endless tubular polyimide film

Next, a method for forming a semiconductive endless tubular polyimide film using the semiconductive aromatic amic acid composition prepared above will be described.

The forming method employs a rotary forming method using a rotating cylinder. First, the semiconductive aromatic amic acid composition is injected into the inner surface of the rotating cylinder, and evenly cast on the entire inner surface.

The injection-casting method is, for example, in a stopped rotating cylinder, after injecting the semiconductive aromatic amic acid composition that obtains the equivalent amount of final film thickness, slowly increase the rotational speed until the centrifugal force acts , spread evenly on the entire inner surface by centrifugal force. Alternatively, injection-casting without the use of centrifugal force is also possible. For example, if a horizontally long slit-shaped nozzle is arranged on the inner surface of a cylinder, and the cylinder is slowly and continuously rotated, the nozzle is also rotated (at a speed faster than the rotation speed). Then, the semiconductive aromatic amic acid composition for molding is uniformly sprayed from the nozzle to the entire inner surface of the cylinder.

Regardless of the method, the inner surface of the rotating cylinder is made into a mirror surface, and barriers to prevent liquid leakage are provided along the circumference at both ends of the cylinder. The cylinder is mounted on a rotating roller and can be rotated indirectly by the rotation of the roller.

For heating, a heat source such as a far-infrared heater is arranged around the cylinder, and indirect heating is performed from the outside. The size of the cylinder depends on the desired size of the semiconducting tubular PI film.

Heating is performed to gradually increase the temperature of the inner surface of the cylinder, at first about 100 to 190°C, preferably about 110 to 130°C (the first heating stage). The heating rate may be, for example, about 1 to 2° C./min. Maintain the above temperature for 1 to 2 hours to volatilize more than half of the solvent and form a self-supporting tubular membrane. In order to imidize, it is necessary to reach a temperature above 280°C, but if it is heated at such a high temperature at the beginning, not only the polyimide will show high crystallization, which will affect the dispersion state of CB, but also exist Problems such as being unable to form a strong film. Therefore, as the first heating stage, the upper limit temperature is controlled at a maximum of about 190°C, at which temperature the polycondensation reaction is terminated, and a tough tubular PI film is obtained.

After this step is completed, next, as a second heating step, heating is performed to complete imidization, and the temperature is about 280 to 400° C. (preferably about 300 to 380° C.). At this time, it is better not to reach the temperature suddenly from the temperature in the first heating stage, but to gradually raise the temperature to reach the temperature.

In addition, the second heating stage can be carried out directly in the state where the endless tubular film is attached to the inner surface of the rotating cylinder, or the endless tubular film can be peeled off from the rotating cylinder after the end of the first heating stage to provide other methods for achieving Heating means for imidization, heating to 280-400°C. The time taken for this imidization is about 2 to 3 hours normally. Therefore, the time taken for the entire process of the first and second heating stages is usually about 4 to 7 hours.

Thus, the semiconductive endless tubular PI film of the present invention was produced. Although the thickness of the film is not particularly limited, it is usually about 50 to 150 μm, preferably about 60 to 120 μm. Especially when it is used for an electrophotographic intermediate transfer tape, it is preferably about 75 to 100 μm.

The semiconductivity of the film is a resistance characteristic determined by volume resistivity (Ω cm) (hereinafter referred to as "VR") and surface resistivity (Ω/□) (hereinafter referred to as "SR"). The characteristics are imparted by the mixing and dispersion of CB powder. And the range of this resistivity can basically be freely changed by the mixing amount of CB powder. Examples of the resistivity range of the film of the present invention include VR: 10 ² to 10 ¹⁴ , SR: 10 ³ to 10 ¹⁵ , and preferred ranges include VR: 10 ⁶ to 10 ¹³ and SR: 10 ⁷ ~10 ¹⁴ . These resistivity ranges can be easily achieved by using the above-mentioned compounding amount of the CB powder. In addition, the CB content in the film of the present invention is usually about 3 to 25% by weight, preferably about 10 to 20% by weight.

The semiconductive PI film of the present invention has very uniform resistivity. That is, the characteristic point of the semiconductive PI film of the present invention is that the variability of the logarithmic conversion values of the surface resistivity SR and the volume resistivity VR is small, and the standard of each logarithmic conversion value at all measurement points in the film is The deviation is within 0.2, preferably within 0.15. In addition, it has a feature that the difference between the surface resistivity (logarithmic conversion value) of the film surface and the back surface is small, and the difference is within 0.4, preferably within 0.2. Furthermore, it has a feature that the value obtained by subtracting the logarithmic conversion value LogVR of the volume resistivity from the logarithmic conversion value LogSR of the surface resistivity can be maintained at a high value of 1.0 to 3.0, preferably 1.3 to 3.0.

The reason why the PI film of the present invention has the above-mentioned excellent electrical properties is believed to be due to the use of a semi-conductive aromatic amide mixed with "aromatic amic acid oligomer" and CB powder in the production process of the film. acid composition. That is, it is considered that in this composition, the CB powder is uniformly dispersed in the aromatic amic acid oligomer, and since the uniform dispersion and high molecular weight can be maintained in the film production process, the PI film of the present invention can be provided. Excellent properties.

The PI film of the present invention has various uses due to its excellent resistance characteristics and other functions. For example, electrophotographic intermediate transfer tapes used in color printers, color copiers, and the like are exemplified as important applications requiring charging characteristics. ^The required semiconductivity (resistivity) ^of the tape is, for example, ^VR109-1012 , ^SR1010-1013 , and the semiconductive endless tubular PI film of the present invention can be suitably applied.

The nonconductive or semiconductive PI film of the present invention has excellent performance as a tape, and has high yield strength (σ _Y ) and high breaking strength (σ _cr ). The yield strength (σ _Y ) is above 120 MPa, especially 120-160 MPa, and the ratio of fracture strength to yield strength (σ _cr /σ _Y ) is above 1.10, especially around 1.10-1.35.

C. The third invention

The semiconductive endless tubular polyimide film (hereinafter also referred to as "semiconductive tubular PI film") of the present invention uses a semiconductive polyimide precursor composition (hereinafter also referred to as "semiconductive polyimide film"). Semiconductive PI Precursor Composition") was fabricated by rotational molding and heat treatment (imidization).

C-1. Semiconductive polyimide precursor composition

The semiconductive polyimide precursor composition of the present invention is obtained by dissolving two or more aromatic tetracarboxylic acid diesters and aromatic diamines in an organic polar solvent in approximately equimolar amounts. In the nylon salt-type monomer solution, mix a high-molecular-weight polyimide precursor solution or a high-molecular-weight polyamide-imide solution to prepare a mixed solution, so that carbon black (hereinafter also referred to as "CB") is uniformly dispersed in the produced in a mixed solution.

(1) Aromatic tetracarboxylic acid diester (half ester)

A mixture of at least one asymmetric aromatic tetracarboxylic diester and at least one symmetric aromatic tetracarboxylic diester is used as a molding raw material for two or more aromatic tetracarboxylic diesters.

Hereinafter, the asymmetric aromatic tetracarboxylic-acid diester used in this invention is demonstrated.

Here, the so-called asymmetric aromatic tetracarboxylic acid includes four carboxyl groups bonded to asymmetric positions on a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring). On the compound, or on the compound with 2 monocyclic aromatic rings (benzene ring, etc.) cross-linked by -CO-, -CH ₂ -, -SO ₂ -, etc. or single bond, 4 carboxyl groups are bonded to non-point Compounds in symmetrical positions.

Specific examples of asymmetric aromatic tetracarboxylic acids include 1,2,3,4-benzenetetracarboxylic acid, 1,2,6,7-naphthalene tetracarboxylic acid, 2,3,3',4 '-Biphenyl tetracarboxylic acid, 2,3,3',4'-benzophenone tetracarboxylic acid, 2,3,3',4'-diphenyl ether tetracarboxylic acid, 2,3,3', 4'-diphenylmethane tetracarboxylic acid, 2,3,3',4'-diphenylsulfone tetracarboxylic acid, etc.

As the asymmetric aromatic tetracarboxylic acid diester (half ester) used in the present invention, the diester of the above-mentioned asymmetric aromatic tetracarboxylic acid can be mentioned, specifically, the above-mentioned asymmetric tetracarboxylic acid diester can be mentioned. Carboxylic acid A compound in which two of the four carboxyl groups are esterified and one of the two adjacent carboxyl groups on the aromatic ring is esterified.

As 2 esters in the above-mentioned asymmetric aromatic tetracarboxylic acid diesters, di-lower alkyl esters can be mentioned, preferably di-C _1-3 alkyl esters such as dimethyl esters, diethyl esters, and dipropyl esters (especially is dimethyl ester).

Among the above-mentioned asymmetric aromatic carboxylic acid diesters, dimethyl 2,3,3',4'-biphenyltetracarboxylate, 2,3,3',4'-biphenyltetracarboxylic acid As diethyl esters, dimethyl 2,3,3',4'-biphenyltetracarboxylate is particularly preferably used.

In addition, the said asymmetric aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, it can be easily produced by known methods such as reacting 1 part of corresponding asymmetric aromatic tetracarboxylic dianhydride with 2 parts (molar ratio) of corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.) . By such a method, a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons of an aromatic ring can be produced by reacting an acid anhydride as a raw material with an alcohol to open the ring.

Next, the symmetrical aromatic tetracarboxylic-acid diester used in this invention is demonstrated below.

Here, the so-called symmetrical aromatic tetracarboxylic acid includes a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring) in which four carboxyl groups are bonded at point-symmetrical positions. compound, or on a compound where two monocyclic aromatic rings (benzene ring, etc.) are cross-linked by -CO-, -O-, -CH ₂ -, -SO ₂ -, etc. Compounds at point symmetric positions.

Specific examples of symmetrical aromatic tetracarboxylic acids include 1,2,4,5-benzenetetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 3,3', 4,4' -Biphenyl tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-diphenyl ether tetracarboxylic acid, 3,3',4,4 '-Diphenylmethane tetracarboxylic acid, 3,3',4,4'-diphenylsulfone tetracarboxylic acid, etc.

As the symmetrical tetracarboxylic acid diester (half ester) used in the present invention, the diester (half ester) of the above-mentioned symmetrical aromatic tetracarboxylic acid can be mentioned, specifically, the above-mentioned symmetrical tetracarboxylic acid diester (half ester) can be mentioned. A compound in which 2 of the 4 carboxyl groups of an acid are esterified and one of the 2 adjacent carboxyl groups on the aromatic ring is esterified.

As two esters in the above-mentioned symmetrical aromatic tetracarboxylic acid diesters, di-lower alkyl esters can be mentioned, preferably C _1-3 alkyl esters such as dimethyl ester, diethyl ester, and dipropyl ester (especially di methyl ester).

Among the above-mentioned symmetrical aromatic carboxylic acid diesters, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, Ethyl ester, dimethyl 1,2,4,5-benzenetetracarboxylate, diethyl 1,2,4,5-benzenetetracarboxylate, particularly preferably 3,3',4,4'-biphenyl Dimethyl tetracarboxylate.

In addition, the said symmetrical aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, it can be easily produced by a known method such as reacting 1 part of the corresponding symmetrical aromatic tetracarboxylic dianhydride with 2 parts (molar ratio) of the corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.). By such a method, a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons of an aromatic ring can be produced by reacting an acid anhydride as a raw material with an alcohol to open the ring.

The mixing ratio of the asymmetric and symmetric aromatic tetracarboxylic acid diesters is specifically defined to be about 10 to 50 mol% (preferably 20 to 40 mol%) for the asymmetric aromatic tetracarboxylic acid diester, and the symmetric The aromatic tetracarboxylic acid diester is about 90 to 50 mol % (preferably 80 to 60 mol %). In particular, it is suitable to use about 20-30 mol% of asymmetric aromatic tetracarboxylic-acid diester and about 70-80 mol% of symmetric aromatic tetracarboxylic-acid diester.

The reason why it is necessary to mix the above-mentioned asymmetric and symmetric aromatic tetracarboxylic acid components is as follows. When only symmetrical aromatic tetracarboxylic acid diesters are used, since the polyimide film exhibits crystallinity, the film is pulverized during heat treatment and cannot be formed into a film. On the other hand, when only an asymmetric aromatic tetracarboxylic acid diester is used, although it can be formed into an endless tubular PI film, the yield strength and elastic modulus of the obtained film are weak, and when used as a rotating belt, not only in the Responsiveness during driving is poor, and problems such as elongation of the rotary belt may occur in the initial stage.

On the other hand, when a mixed aromatic tetracarboxylic acid diester is used, extremely high film forming properties (formability) can be obtained, and a semiconductive endless tubular PI film having high yield strength and high modulus of elasticity can be obtained.

In addition, the applicant believes that by adding an asymmetric aromatic tetracarboxylic acid diester, the polyamic acid molecules can be bent to generate flexibility.

Therefore, the coexistence effect of the above-mentioned symmetric and asymmetric aromatic tetracarboxylic acid derivatives can be most effectively exhibited when the mixing ratio of the two is as shown above.

(2) Aromatic diamine

Examples of aromatic diamines include compounds having two amino groups on one aromatic ring (benzene ring, etc.), or compounds with two or more aromatic rings (benzene rings, etc.) represented by -O-, -S-, -CO- , -CH ₂ -, -SO-, -SO ₂ - or a compound having two amino groups cross-linked by a single bond. Specifically, for example, p-phenylene diamine, o-phenylene diamine, m-phenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylcarbonyl, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, etc. Among them, 4,4'-diaminodiphenyl ether is particularly preferable. This is because, by using these aromatic diamines, the reaction proceeds more smoothly and a tougher and higher heat-resistant film can be produced.

(3) Nylon salt type monomer solution

The two or more kinds of aromatic tetracarboxylic acid diesters and aromatic diamines are uniformly dissolved in an organic polar solvent in approximately equimolar amounts to prepare a nylon salt-type monomer solution. When dissolving the two components uniformly in the organic polar solvent, it may be heated as necessary (for example, about 40 to 70° C.). What is necessary is just to dissolve both components in an organic polar solvent using well-known mixing methods, such as stirring.

As the organic polar solvent used, preferably an aprotic organic polar solvent, for example, use N-methyl-2-pyrrolidone (hereinafter referred to as "NMP"), N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolinone, etc. One or a mixed solution of two or more of them may be used. NMP is particularly preferred. The amount of organic polar solvent used is about 100 to 300 parts by weight (preferably 120 to 200 parts by weight) relative to 100 parts by weight of the total amount of two or more aromatic tetracarboxylic acid diesters and aromatic diamines as raw materials. parts) can be.

The applicant believes that the above-mentioned nylon salt-type monomer solution, for example, in an organic polar solvent, the ion pair of the carboxylic acid ion of the aromatic tetracarboxylic acid diester and the ammonium ion of the aromatic diamine is substantially maintained as a monomer state (for example, refer to the following formula). In addition, since it is substantially in a monomer state, it is easy to dissolve in the above-mentioned organic polar solvent, and there is an advantage that the amount of solvent used can be reduced as much as possible.

(In the formula, Ar represents a quaternary group obtained by removing 2 carboxyl groups and 2 ester groups from an aromatic tetracarboxylic acid, Ar' represents a 2-valent group obtained by removing 2 amino groups from an aromatic diamine, R represents an alkane base.)

(4) High molecular weight polyimide precursor solution or high molecular weight polyamideimide solution

As a high molecular weight polyimide precursor solution, a polyamic acid solution with a number average molecular weight of 10,000 or more is used; as a high molecular weight polyamide-imide solution, a polyamide-imide solution with a number average molecular weight of 10,000 or more is used. In addition, the number average molecular weight in this specification is the value measured by the GPC method (solvent: NMP, polyethylene oxide conversion).

Polyamic acid solution

The polyamic acid solution having a number average molecular weight of 10000 or more can be produced by a known method using, for example, biphenyltetracarboxylic dianhydride and diaminodiphenyl ether components as starting materials in an organic polar solvent. As the organic polar solvent, the organic polar solvent used in the above-mentioned nylon salt type monomer solution can be used.

Examples of biphenyltetracarboxylic dianhydride include 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3',4,4'-biphenyltetracarboxylic Acid dianhydride (s-BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride, etc.

Examples of the diaminodiphenyl ether component include 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and the like.

The compounding quantity of a biphenyltetracarboxylic dianhydride and a diaminodiphenyl ether component should just be a substantially equimolar quantity. The polycondensation reaction of the two can adopt a known method, for example, the method that can be cited is to add a biphenyltetracarboxylic acid component to a solution containing a diaminodiphenyl ether component at room temperature (about 15 to 30° C.), This is amidated to prepare a polyamic acid solution. The number average molecular weight of the obtained polyamic acid is 10000 or more, Preferably it is 12000-20000.

polyamideimide solution

A polyamide-imide solution having a number average molecular weight of 10,000 or more is produced, for example, by a well-known reaction such as polycondensation reaction of an acid anhydride composed of trimellitic anhydride and benzophenone tetracarboxylic anhydride and an aromatic isocyanate in an organic polar solvent . As the organic polar solvent, the organic polar solvent used for the above-mentioned nylon salt type monomer solution can be used.

Among the acid anhydrides, about 70 to 95 mol % of trimellitic anhydride and about 5 to 30 mol % of benzophenone tetracarboxylic anhydride are sufficient.

Examples of the aromatic isocyanate include biphenylene diisocyanate, 3,3'-diphenylsulfone diisocyanate, isophorone diisocyanate, 1,4-diisocyanate, 4,4'-dicyclohexyl Methane diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, 1,4-cyclohexylene diisocyanate and the like.

The total number of carboxyl groups and acid anhydride groups in the acid component is preferably used in an amount approximately equal to the total number of aromatic isocyanate groups.

The number average molecular weight of polyamideimide is 10,000 or more, preferably about 15,000 to 20,000.

(5) mixed solution

A mixed solution is prepared by mixing the above-mentioned nylon salt-type monomer solution and a high-molecular-weight polyimide precursor solution or a high-molecular-weight polyamide-imide solution. Known methods such as a screw stirrer, a magnetic stirrer, and a ball mill can be used for this mixing.

The mixing amount (ratio) of the two is, relative to 100 parts by weight of the non-volatile matter weight in the nylon salt type monomer solution, the high molecular weight polyimide precursor solution (especially the polyamic acid with a number average molecular weight of more than 10000 solution), or high-molecular-weight polyamide-imide solution (polyamide-imide solution with a number average molecular weight of more than 10000), the non-volatile weight is preferably about 10 to 50 parts by weight (preferably about 20 to 30 parts by weight) scope. In addition, the "non-volatile matter weight" used in this specification means the quantity measured by the method as described in Example C-1.

In addition, if the non-volatile weight of the high-molecular-weight polyimide precursor solution or the high-molecular-weight polyamide-imide solution is less than 10 parts by weight relative to the non-volatile weight of the nylon salt type monomer, it is difficult to achieve the present invention. In addition, if carbon black is added to a solution exceeding 50 parts by weight, the increase rate of viscosity will be significantly increased, and the pulverization of carbon black will become difficult. As a result, more organic polar solvents need to be added to improve production efficiency. reduce.

(6) Semiconductive PI precursor composition

Next, the CB powder was uniformly dispersed in the mixed solution to prepare a semiconductive PI precursor composition.

The reason for using CB powder to impart resistance characteristics is (compared with other commonly known metal and metal oxide conductive materials), mixing dispersibility and stability with the prepared monomer mixed solution (mixing Time-dependent change after dispersion) is excellent, and has no adverse effect on the polycondensation reaction.

The CB powder has a variety of physical properties (resistance, volatile matter, specific surface area, particle size, pH value, DBP oil absorption) according to its manufacturing raw materials (natural gas, acetylene gas, tar, etc.) and manufacturing conditions (combustion conditions) wait). It is better to select a CB powder that is stable and easy to obtain without causing deviation in the desired resistance even with a small amount of mixing and dispersion.

The conductive CB powder usually has an average particle diameter of about 15 to 65 nm, and is preferably about 20 to 40 nm when it is used in an electrophotographic intermediate transfer belt used in a color printer, a color copier, or the like.

Carbon blacks with high conductivity indicators such as ketjen black and acetylene black are prone to secondary aggregation (structure, structure), which is easy to cause a chain of conductivity, and it is difficult to control it in the semi-conductive area. Therefore, it is effective to use acidic carbon black that is less prone to structure formation.

For example, channel black, oxidized furnace black, etc. are mentioned. Specifically, Special Black 4 (pH 3, volatile content 14%, particle diameter 25 nm) and Special Black 5 (pH 3, volatile content 15%, particle diameter 20 nm) manufactured by Degusa Co., Ltd. can be exemplified.

The mixing method of the CB powder is not particularly limited as long as the CB powder is uniformly mixed and dispersed in the mixed solution C. For example, a ball mill, a wheel mixer, an ultrasonic mill, etc. are used.

The amount of CB powder to be added is based on (1) the aromatic tetracarboxylic acid component and the organic diamine as the nylon salt-type monomer raw material, and (2) the acid anhydride and the The total amount of diamine, or acid anhydride and aromatic isocyanate which are raw materials of high-molecular-weight polyamideimide is 100 parts by weight, preferably about 5 to 40 parts by weight (preferably about 10 to 30 parts by weight). Here, the reason why CB powder is used within the above-mentioned range is to impart volume resistivity (VR) and surface resistivity (SR) in the semiconducting region to the film. The lower limit is about 5 parts by weight or more because, in order to obtain sufficient conductivity, the amount of this level is necessary; the upper limit is about 40 parts by weight because, while exhibiting lower resistance, maintain formability and prevent film The reduction of its own physical characteristics.

The concentration of nonvolatile matter in the semiconductive PI precursor composition is about 20 to 60% by weight, and the concentration of CB powder in the nonvolatile matter is about 5 to 30% by weight (preferably about 9 to 23% by weight). In addition, the "non-volatile matter concentration" used in this specification means the concentration measured by the method as described in Example C-1.

In addition, imidazole compounds (2-methylimidazole, 1,2-dimethylimidazole, 2-methyl-4-methylimidazole, imidazole, 2-ethyl-4-ethylimidazole, 2-phenylimidazole), surfactants (fluorosurfactants, etc.) and other additives.

In this way, a semiconductive PI precursor composition for molding in which CB powder is uniformly dispersed was produced.

In the semiconductive PI precursor composition of the present invention, carbon black is uniformly dispersed by mixing a high-molecular-weight polyimide precursor solution or a high-molecular-weight polyamide-imide solution with a nylon salt-type monomer The storage stability is significantly improved. Furthermore, a conductive tubular polyimide-based film obtained by rotationally molding a semiconductive PI precursor composition using it is endowed with conductivity having an extremely stable and uniform resistivity in the thickness direction. . Although the reason is not certain, the applicant's reason is that there is a polymer with a higher number-average molecular weight in the polyimide precursor composition, and the polymer component and carbon black are physically connected or viscous, inhibiting Agglomeration of carbon black. In addition, the applicant believes that the viscosity of the polymer not only alleviates the influence of the centrifugal force on the carbon black particles in the rotational molding process, but also alleviates the influence of temperature convection and evaporation convection when the solvent is volatilized. Furthermore, it also has the effect of slowing down the polyimidization reaction rate by heating.

II. Conductive endless tubular polyimide film

Next, a method for forming a conductive tubular PI-based film using the semiconductive PI precursor composition prepared above will be described.

The forming method employs a rotary forming method using a rotating cylinder. First, the semiconductive PI precursor composition is injected into the inner surface of the rotating cylinder, and evenly cast on the entire inner surface.

The injection-casting method is, for example, in a stopped rotating cylinder, after injecting the semiconductive PI precursor composition in an amount equivalent to the final film thickness, slowly increasing the rotation speed until the centrifugal force acts, Spread evenly on the entire inner surface by centrifugal force. Alternatively, injection-casting without the use of centrifugal force is also possible. For example, a horizontally long slit-shaped nozzle is arranged on the inner surface of a rotating cylinder, and the cylinder is slowly and continuously rotated, and the nozzle is also rotated (at a speed faster than the rotation speed). Then, the semiconductive PI precursor composition for molding was uniformly sprayed from the nozzle to the entire inner surface of the cylinder.

Regardless of the method, the inner surface of the rotating cylinder is made into a mirror surface, and barriers to prevent liquid leakage are provided along the circumference at both ends of the cylinder. The cylinder is mounted on a rotating roller and can be rotated indirectly by the rotation of the roller.

For heating, a heat source such as a far-infrared heater is arranged around the cylinder, and indirect heating is performed from the outside. The size of the cylinder depends on the desired size of the semiconducting tubular PI film.

Heating is performed to gradually increase the temperature of the inner surface of the cylinder, at first about 100 to 190°C, preferably about 110 to 130°C (the first heating stage). The heating rate may be, for example, about 1 to 2° C./min. Maintain the above temperature for 1 to 3 hours to volatilize more than half of the solvent and form a self-supporting tubular membrane. In order to imidize, it is necessary to reach a temperature above 280°C, but if it is heated at such a high temperature at the beginning, not only will the polyimide show high crystallization, which will affect the dispersion state of CB, but also There were problems such as being unable to form a strong film. Therefore, as the first heating stage, the upper limit temperature is controlled at a maximum of about 190°C, at which temperature the polycondensation reaction is terminated, and a tough tubular PI film is obtained.

After this step is completed, next, as a second heating step, heating is performed to complete imidization, and the temperature is about 280 to 400° C. (preferably about 300 to 380° C.). At this time, it is better not to reach the temperature suddenly from the temperature in the first heating stage, but to gradually raise the temperature to reach the temperature.

In addition, the second heating stage can be carried out directly in the state where the endless tubular film is attached to the inner surface of the rotating cylinder, or the endless tubular film can be peeled off from the rotating cylinder after the end of the first heating stage to provide other methods for achieving Heating means for imidization, heating to 280-400°C. The time taken for this imidization is about 2 to 3 hours normally. Therefore, the time taken for the entire process of the first and second heating stages is usually about 4 to 7 hours.

Thus, the conductive endless tubular polyimide-based film of the present invention was produced. The thickness of the film is not particularly limited, but is usually about 30 to 200 μm, preferably about 50 to 120 μm. Especially when used for an electrophotographic intermediate transfer tape, it is preferably about 70 to 100 μm.

The semiconductivity of the film is a resistance characteristic determined by volume resistivity (Ω cm) (hereinafter referred to as "VR") and surface resistivity (Ω/□) (hereinafter referred to as "SR"). The characteristics are imparted by the mixing and dispersion of CB powder. And the range of this resistivity can basically be freely changed by the mixing amount of CB powder. Examples of the resistivity range of the film of the present invention include VR: 10 ² to 10 ¹⁴ , SR: 10 ³ to 10 ¹⁵ , and preferred ranges include VR: 10 ⁶ to 10 ¹³ and SR: 10 ⁷ ~10 ¹⁴ . These resistivity ranges can be easily achieved by using the above-mentioned compounding amount of the CB powder. In addition, the CB content in the film of the present invention is usually about 5 to 30% by weight, preferably about 9 to 23% by weight.

The semiconductive PI film of the present invention has very uniform resistivity. That is, the characteristic point of the semiconductive PI film of the present invention is that the variability of the logarithmic conversion values of the surface resistivity SR and the volume resistivity VR is small, and the standard of each logarithmic conversion value at all measurement points in the film is The deviation is within 0.2, preferably within 0.15. In addition, it has a feature that the difference between the surface resistivity (logarithmic conversion value) of the film surface and the back surface is small, and the difference is within 0.4, preferably within 0.2. Furthermore, it has a feature that the value obtained by subtracting the logarithmic conversion value LogVR of the volume resistivity from the logarithmic conversion value LogSR of the surface resistivity can be maintained at a high value of 1.0 to 3.0, preferably 1.5 to 3.0.

The reason why the PI film of the present invention has the above-mentioned excellent electrical characteristics is considered to be that, by mixing a high molecular weight polyimide precursor or a high molecular weight polyamideimide precursor solution, CB is physically uniformly incorporated in the film. In the intertwined structure of polymer chains, it is difficult to be affected by solvent evaporation in the film production process and high molecular weight of nylon salt-type monomers, etc., and can achieve a homogeneous CB dispersion state in the precursor composition solution A conductive endless tubular polyimide film was obtained.

The PI film of the present invention has various uses due to its excellent resistance characteristics and other functions. For example, electrophotographic intermediate transfer tapes used in color printers, color copiers, and the like are exemplified as important uses requiring charging characteristics. The required semiconductivity (resistivity) of the tape is, for example, ^VR109-1012 , ^SR1010-1013 , and the semiconductive endless tubular ^{PI -} based film of the present invention can be suitably applied.

The semiconductive PI film of the present invention has excellent performance as a tape, and has high yield strength (σ _Y ) and high breaking strength (σ _cr ). The yield strength (σ _Y ) is above 120 MPa, especially 120-160 MPa, and the ratio of fracture strength to yield strength (σ _cr /σ _Y ) is above 1.10, especially around 1.10-1.35.

D. The fourth invention

The semiconductive endless tubular polyimide film of the present invention (hereinafter also referred to as "semiconductive tubular PI film") uses a semiconductive high-concentration polyimide precursor composition (hereinafter also referred to as "semiconductive tubular PI film"). Highly Concentrated PI Precursor Composition") is produced by rotational molding and heat treatment (imidization).

D-1. Semiconductive high-concentration polyimide precursor composition

The semiconductive high-concentration polyimide precursor composition of the present invention is in the carbon black dispersion liquid that carbon black (hereinafter also referred to as "CB") is uniformly dispersed in the organic polar solvent, approximately Produced by dissolving aromatic tetracarboxylic acid diester and aromatic diamine in equimolar amounts. That is, it is characterized by adding an equimolar amount of a monomer (an aromatic tetracarboxylic acid diester and an aromatic diamine in an equimolar amount) as a molding raw material to a uniform dispersion of CB prepared in advance. while manufacturing.

(1) Carbon black dispersion

In the present invention, conductive CB powder is used in the PI precursor composition in order to impart semiconductivity. The reason for using this CB powder is that (compared with other commonly known metal or metal oxide conductive materials) the mixed dispersibility and dispersibility of CB in the prepared semiconductive high-concentration polyimide precursor composition It is excellent in dispersion stability (change with time after mixing and dispersion), and has no adverse effect on the polycondensation reaction.

The CB powder has a variety of physical properties (resistance, volatile matter, specific surface area, particle size, pH value, DBP oil absorption) according to its manufacturing raw materials (natural gas, acetylene gas, tar, etc.) quantity, etc.). It is better to select a CB powder that is stable and easy to obtain without causing deviation in the desired resistance even with a small amount of mixing and dispersion.

The conductive CB powder usually has an average particle diameter of about 15 to 65 nm, and is preferably about 20 to 40 nm when it is used in an electrophotographic intermediate transfer belt used in color printers and color copiers.

Carbon blacks with high conductivity indicators such as Ketjen black and acetylene black are prone to secondary aggregation (structural structure), which is likely to cause a chain of conductivity, and it is difficult to control it in the semi-conductive region. Therefore, it is effective to use acidic carbon black that is less prone to structure formation.

For example, channel black, oxidized furnace black, etc. are mentioned. Specifically, Special Black 4 (pH 3, volatile content 14%, particle diameter 25 nm) and Special Black 5 (pH 3, volatile content 15%, particle diameter 20 nm) manufactured by Degusa Co., Ltd. can be exemplified.

The organic polar solvent used as the carbon black dispersion is preferably an aprotic organic polar solvent, for example, N-methyl-2-pyrrolidone (hereinafter referred to as "NMP"), N, N-dimethyl Diethyl formamide, N, N-diethyl formamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, etc. . One or a mixed solution of two or more of them may be used. NMP is particularly preferred.

The carbon black dispersion is produced by uniformly dispersing CB powder in the above-mentioned organic polar solvent. The mixing method of the CB powder is not particularly limited as long as it is a method of uniformly mixing and dispersing the CB powder in an organic polar solvent. For example, a ball mill, a wheel mixer, an ultrasonic mill, etc. are used.

The compounding quantity of CB powder is about 3-25 weight part with respect to 100 weight part of organic polar solvents, Preferably it is about 5-15 weight part. The range of this compounding quantity is the range which does not increase the viscosity of an organic polar solvent, or CB does not form a secondary aggregate by van der Waals' force. In addition, the reason why the lower limit is 3 parts by weight or more with respect to 100 parts by weight of the organic polar solvent is that it is necessary not to lower the non-volatile matter concentration of the semiconductive high-concentration polyimide precursor composition produced. amount. The reason why the upper limit is 25 parts by weight or less is to make the distance between uniformly dispersed CB particles sufficient and to prevent secondary aggregation due to van der Waals force.

(2) Aromatic tetracarboxylic acid diester (half ester)

A mixture of at least one asymmetric aromatic tetracarboxylic diester and at least one symmetric aromatic tetracarboxylic diester is used as a molding raw material for two or more aromatic tetracarboxylic diesters.

The asymmetric aromatic tetracarboxylic diester used in the present invention will be described below.

Here, the term "asymmetric aromatic tetracarboxylic acid" includes a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring, etc.) in which four carboxyl groups are bonded to asymmetric The compound at the position, or on the compound where two monocyclic aromatic rings (benzene ring, etc.) are cross-linked by -CO-, -CH ₂ -, -SO ₂ -, etc. or a single bond, 4 carboxyl groups are bonded to non-point Symmetrical compounds.

Specific examples of asymmetric aromatic tetracarboxylic acids include 1,2,3,4-benzenetetracarboxylic acid, 1,2,6,7-naphthalene tetracarboxylic acid, 2,3,3',4 '-Biphenyl tetracarboxylic acid, 2,3,3',4'-benzophenone tetracarboxylic acid, 2,3,3',4'-diphenyl ether tetracarboxylic acid, 2,3,3', 4'-diphenylmethane tetracarboxylic acid, 2,3,3',4'-diphenylsulfone tetracarboxylic acid, etc.

As the asymmetric aromatic tetracarboxylic acid diester (half ester) used in the present invention, the diester of the above-mentioned asymmetric aromatic tetracarboxylic acid can be mentioned, specifically, the above-mentioned asymmetric aromatic tetracarboxylic acid diester can be mentioned. A compound in which two of the four carboxyl groups of the tetracarboxylic acid are esterified and one of the two adjacent carboxyl groups on the aromatic ring is esterified.

As two esters in the above-mentioned asymmetric aromatic tetracarboxylic acid diesters, di-lower alkyl esters can be mentioned, preferably C _1-3 alkyl esters such as dimethyl esters, diethyl esters, and dipropyl esters (especially is dimethyl ester).

Among the above-mentioned diesters of asymmetric aromatic carboxylic acids, dimethyl 2,3,3',4'-biphenyltetracarboxylate, 2,3,3',4'-biphenyltetracarboxylate Acid diethyl ester, particularly preferably use dimethyl 2,3,3',4'-biphenyltetracarboxylate.

In addition, the said asymmetric aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, it can be easily produced by reacting 1 part of the corresponding asymmetric aromatic tetracarboxylic dianhydride with 2 parts (molar ratio) of the corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.). By such a method, an acid anhydride as a raw material reacts with an alcohol to open a ring, and a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons on the aromatic ring can be produced.

Next, the diester of the symmetrical aromatic tetracarboxylic acid used in this invention is demonstrated below.

Here, the symmetrical aromatic tetracarboxylic acid includes four carboxyl groups bonded at point-symmetrical positions on a monocyclic or polycyclic aromatic ring (benzene ring, naphthalene ring, biphenyl ring, anthracene ring, etc.). compound, or on a compound where two monocyclic aromatic rings (benzene ring, etc.) are cross-linked by -CO-, -O-, -CH ₂ -, -SO ₂ -, etc. Compounds with point symmetry.

Specific examples of symmetrical aromatic tetracarboxylic acids include 1,2,4,5-benzenetetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 3,3', 4,4' -Biphenyl tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-diphenyl ether tetracarboxylic acid, 3,3',4,4 '-Diphenylmethane tetracarboxylic acid, 3,3',4,4'-diphenylsulfone tetracarboxylic acid, etc.

As the symmetrical aromatic tetracarboxylic acid diester (half ester) used in the present invention, the diester (half ester) of the above-mentioned symmetrical aromatic tetracarboxylic acid can be mentioned, specifically, the above-mentioned symmetrical aromatic tetracarboxylic acid diester (half ester) can be mentioned An aromatic tetracarboxylic acid is a compound in which two carboxyl groups are esterified among the four carboxylic acids and one of the two adjacent carboxyl groups on the aromatic ring is esterified.

As two esters in the above-mentioned symmetrical aromatic tetracarboxylic acid diesters, di-lower alkyl esters can be mentioned, preferably C _1-3 alkyl esters such as dimethyl ester, diethyl ester, and dipropyl ester (especially di methyl ester).

Among the above-mentioned symmetrical aromatic carboxylic acid diesters, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester, Ethyl ester, dimethyl 1,2,4,5-benzenetetracarboxylate, diethyl 1,2,4,5-benzenetetracarboxylate, particularly preferably 3,3',4,4'-biphenyl Dimethyl tetracarboxylate.

In addition, the said symmetrical aromatic tetracarboxylic-acid diester can use a commercially available thing or can manufacture by a well-known method. For example, it can be easily produced by a known method such as reacting 1 part of the corresponding symmetrical aromatic tetracarboxylic dianhydride with 2 parts (molar ratio) of the corresponding alcohol (lower alcohol, preferably C _1-3 alcohol, etc.). By such a method, an acid anhydride as a raw material reacts with an alcohol to open a ring, and a diester (half-ester) having an ester group and a carboxyl group on adjacent carbons on the aromatic ring can be produced.

The mixing ratio of asymmetric and symmetric aromatic tetracarboxylic acid diesters is specifically defined as 10-50 mol% (preferably 20-40 mol%) for asymmetric aromatic tetracarboxylic acid diesters, and about 20-40 mol% for symmetric aromatic tetracarboxylic The tetracarboxylic acid diester is about 90 to 50 mol % (preferably 80 to 60 mol %). In particular, it is suitable to use about 20-30 mol% of asymmetric aromatic tetracarboxylic-acid diester, and about 70-80 mol% of symmetric aromatic tetracarboxylic-acid diester.

The reason why it is necessary to mix the above-mentioned symmetric and asymmetric aromatic tetracarboxylic diesters is as follows. When only symmetrical aromatic tetracarboxylic acid diesters are used, since the polyimide film exhibits crystallinity, the film is pulverized during heat treatment and cannot be formed into a film. On the other hand, when only asymmetric aromatic tetracarboxylic acid derivatives are used, although it can be formed into an endless tubular PI film, the yield strength and elastic modulus of the obtained film are weak, and when used as a rotating belt, not only in the Responsiveness during driving is poor, and problems such as elongation of the rotary belt may occur in the initial stage.

On the other hand, when a mixed aromatic tetracarboxylic acid diester is used, extremely high film forming properties (formability) can be obtained, and a semiconductive endless tubular PI film having high yield strength and high modulus of elasticity can be obtained.

In addition, the applicant believes that by adding an asymmetric aromatic tetracarboxylic acid diester, the polyamic acid molecules can be bent to generate flexibility.

Furthermore, the coexistence effect of the above-mentioned symmetrical and asymmetrical aromatic tetracarboxylic acid derivatives can be exhibited most effectively when the mixing ratio of the two is as shown above.

(3) Aromatic diamine

Examples of aromatic diamines include compounds having two amino groups on one aromatic ring (benzene ring, etc.), or compounds with two or more aromatic rings (benzene rings, etc.) represented by -O-, -S-, -CO- , -CH ₂ -, -SO-, -SO ₂ - or a compound having two amino groups cross-linked by a single bond. Specifically, for example, p-phenylene diamine, o-phenylene diamine, m-phenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylcarbonyl, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, etc. Among them, 4,4'-diaminodiphenyl ether is particularly preferable. This is because, by using these aromatic diamines, the reaction proceeds more smoothly and a tougher and higher heat-resistant film can be produced.

(4) Semiconductive high-concentration polyimide precursor composition

Next, an aromatic tetracarboxylic acid diester and an aromatic diamine were added and dissolved in approximately equimolar amounts to the obtained carbon black dispersion.

A semiconductive high-density polyimide precursor composition is produced by adding the above-mentioned aromatic tetracarboxylic acid component and organic diamine to the carbon black dispersion liquid in an approximately equimolar amount, and stirring and dissolving uniformly. When dissolving both components uniformly in the carbon black dispersion liquid, it may heat as needed (for example, about 40-70 degreeC). What is necessary is just to dissolve both components in an organic polar solvent using well-known mixing methods, such as stirring.

Adjust the compounding quantity of aromatic tetracarboxylic acid diester and aromatic diamine, make relative to the total amount of aromatic tetracarboxylic acid diester and aromatic diamine 100 parts by weight, the carbon black in the carbon black dispersion liquid is 5～ About 35 parts by weight (preferably about 8 to 30 parts by weight) will suffice. The reason why the compounding amount is within the above range is to impart volume resistivity (VR) and surface resistivity (SR) in the semiconductive region to the film.

The applicant believes that the above-mentioned semiconductive high-concentration polyimide precursor composition, for example, in an organic polar solvent, the ion pair of the carboxylic acid ion of the aromatic tetracarboxylic acid diester and the ammonium ion of the aromatic diamine , substantially remains in the monomeric state (for example, refer to the following formula).

(In the formula, Ar represents a quaternary group obtained by removing 2 carboxyl groups and 2 ester groups from an aromatic tetracarboxylic acid, Ar' represents a 2-valent group obtained by removing 2 amino groups from an aromatic diamine, R represents an alkane base.)

In addition, since it is substantially in a monomer state, it is easy to dissolve in the above-mentioned organic polar solvent, and there is an advantage that the amount of solvent used can be reduced as much as possible. In addition, the non-volatile matter concentration in the composition can be set to a high concentration of, for example, about 35 to 60% by weight, preferably about 40 to 60% by weight. The CB concentration in this non-volatile component can be set, for example, to about 4 to 30% by weight, preferably about 10 to 25% by weight. In addition, the "non-volatile matter concentration" used in this specification means the concentration measured by the method as described in Example D-1.

In addition, imidazole compounds (2-methylimidazole, 1,2-dimethylimidazole, 2-methyl-4-methylimidazole, imidazole, 2-ethyl-4-ethylimidazole, 2-phenylimidazole), surfactants (fluorosurfactants, etc.) and other additives.

In this way, a semiconductive PI precursor composition in which CB powder is uniformly dispersed and non-volatile matter is dissolved or dispersed at a high concentration is produced.

In the semiconductive high-concentration PI precursor composition of the present invention, a carbon black dispersion liquid in which CB powder is uniformly dispersed is prepared, and aromatic tetracarboxylic acid diester and aromatic diamine components are dissolved in the carbon black dispersion. In the black dispersion, the CB powder is uniformly dispersed, and the storage stability of the uniformly dispersed CB powder is significantly improved. Furthermore, a conductive polyimide tube obtained by rotationally molding its semiconductive PI precursor composition was endowed with conductivity having an extremely stable and uniform resistivity in the thickness direction.

In the semiconductive high-concentration PI precursor composition of the present invention, the non-volatile matter concentration can be remarkably increased to about 35 to 60% by weight because the monomer as a molding raw material is dissolved in the carbon black dispersion. Therefore, using the semiconductive high-concentration PI precursor composition of the present invention, a thick film can be easily produced, and the amount of solvent used is small, so the cost can be suppressed, and the evaporation and removal of the solvent can be facilitated.

Furthermore, since the semiconductive high-concentration PI precursor composition of the present invention can also have a viscosity as high as about 10 to 60 poise, the PI film is less likely to be affected by the centrifugal force of spin forming.

D-2. Semiconductive endless tubular polyimide film

Next, a method for forming a semiconductive endless tubular PI film using the semiconductive PI precursor composition prepared above will be described.

The forming method employs a rotary forming method using a rotating cylinder. First, the semiconductive PI precursor composition is injected into the inner surface of the rotating cylinder, and evenly cast on the entire inner surface.

The injection-casting method is, for example, in a stopped rotating cylinder, after injecting the semiconductive PI precursor composition in an amount equivalent to the final film thickness, slowly increasing the rotation speed until the centrifugal force acts, Spread evenly on the entire inner surface by centrifugal force. Alternatively, injection-casting without the use of centrifugal force is also possible. For example, a horizontally long slit-shaped nozzle is arranged on the inner surface of a rotating cylinder, and the cylinder is slowly and continuously rotated, and the nozzle is also rotated (at a speed faster than the rotation speed). Then, the semiconductive PI precursor composition for molding was uniformly sprayed from the nozzle to the entire inner surface of the cylinder. The cylinder is mounted on a rotating roller and can be rotated indirectly by the rotation of the roller.

For heating, a heat source such as a far-infrared heater is arranged around the cylinder, and indirect heating is performed from the outside. The size of the cylinder depends on the desired size of the semiconducting tubular PI film.

Heating is performed to gradually increase the temperature of the inner surface of the cylinder, at first about 100 to 190°C, preferably about 110°C to 130°C (the first heating stage). The heating rate may be, for example, about 1 to 2° C./min. Maintain the above temperature for 1 to 3 hours to volatilize more than half of the solvent and form a self-supporting tubular membrane. In order to imidize, it is necessary to reach a temperature above 280°C, but if it is heated at such a high temperature at the beginning, not only the polyimide will show high crystallization, which will affect the dispersion state of CB, but also exist Problems such as being unable to form a strong film. Therefore, as the first heating stage, the upper limit temperature is controlled at a maximum of about 190°C, at which temperature the polycondensation reaction is terminated, and a tough tubular PI film is obtained.

After this step is completed, next, as a second heating step, heating is performed to complete imidization, and the temperature is about 280 to 400° C. (preferably about 300 to 380° C.). At this time, it is better not to reach the temperature suddenly from the heating temperature in the first stage, but to gradually increase the temperature to reach the temperature.

In addition, the second stage of heating can be carried out directly in the state where the endless tubular film is attached to the inner surface of the rotating cylinder, or the endless tubular film can be peeled off from the rotating cylinder after the end of the first heating stage to provide other methods for achieving Heating means for imidization, heating to 280-400°C. The time taken for this imidization is about 2 to 3 hours normally. Therefore, the time required for the entire process of the first and second heating stages is usually about 4 to 7 hours.

This produced the semiconductive tubular PI film of the present invention. The thickness of the film is not particularly limited, but is usually about 30 to 200 μm, preferably about 60 to 120 μm. Especially when it is used for an electrophotographic intermediate transfer tape, it is preferably about 75 to 100 μm.

The semiconductivity of the film is a resistance characteristic determined by volume resistivity (Ω cm) (hereinafter referred to as "VR") and surface resistivity (Ω/□) (hereinafter referred to as "SR"). The characteristics are imparted by the mixing and dispersion of CB powder. And the range of this resistance can basically be freely changed by the mixing amount of CB powder. Examples of the resistivity range of the film of the present invention include VR: 10 ² to 10 ¹⁴ , SR: 10 ³ to 10 ¹⁵ , and preferred ranges include VR: 10 ⁶ to 10 ¹³ and SR: 10 ⁷ ~10 ¹⁴ . These resistivity ranges can be easily achieved by using the above-mentioned compounding amount of the CB powder. In addition, the CB content in the film of the present invention is usually about 5 to 25% by weight, preferably about 8 to 20% by weight.

The semiconductive tubular PI film of the present invention has a very homogeneous resistivity. That is, the characteristic point of the semiconductive tubular PI film of the present invention is that the variability of the logarithmic conversion values of the surface resistivity SR and the volume resistivity VR is small, and that the logarithmic conversion values of the respective logarithmic conversion values are small at all measurement points in the film. The standard deviation is within 0.2, preferably 0.15 or less. In addition, it has a feature that the difference between the surface resistivity (logarithmic conversion value) of the film surface and the back surface is small, and the difference is within 0.4, preferably within 0.2. Furthermore, it has a feature that the value obtained by subtracting the logarithmic conversion value LogVR of the volume resistivity from the logarithmic conversion value LogSR of the surface resistivity can be maintained at a high value of 1.0 to 3.0, preferably 1.5 to 3.0.

The PI film of the present invention has various uses due to its excellent resistance characteristics and other functions. For example, electrophotographic intermediate transfer tapes used in color printers, color copiers, and the like are exemplified as important uses requiring charging characteristics. ^The required semiconductivity (resistivity) of the tape is, for example, ^VR109-1012 , ^SR1010-1013 , and the semiconductive endless tubular PI film of ^the present invention can be suitably applied.

The semiconductive PI film of the present invention has excellent performance as a tape, and has high yield strength (σ _Y ) and high breaking strength (σ _cr ). The yield strength (σ _Y ) is above 120 MPa, especially 120-160 MPa, and the ratio of fracture strength to yield strength (σ _cr /σ _Y ) is above 1.10, especially around 1.10-1.35.

Example

The present invention will be described in more detail below using comparative examples and examples together, but the present invention is not limited to these examples.

A. The first invention

The first invention will be described in more detail by way of comparative examples and examples.

The yield strength (yield point stress), fracture strength, volume resistivity (VR), surface resistivity (SR) and nonvolatile concentration described in this example are values measured as follows.

[Yield strength (MPa) (abbreviated as σ _Y ) and breaking strength (MPa) (abbreviated as σ _cr )]

The film obtained in each example was cut into a width of 5 mm and a length of 100 mm, which was used as a test piece, and a uniaxial tensile tester (odograph manufactured by Shimadzu Corporation) was used to pull the film at a distance of 40mm, deformation speed 200mm/min to measure. Read σ _Y and σ _cr from the recorded SS curve.

The yield strength and fracture strength are very important strength factors in the material design of the belt, and at least the yield strength needs to be 120 MPa. This is because plastic deformation (dimension change due to elongation) cannot occur due to stress when a load is applied during assembly.

In addition, it is also necessary that the breaking strength is greater than the yield strength, so as to impart life resistance (toughness) against rotation of the belt. As its target, at least σ _cr /σ _Y =1.10 or more is required.

[VR and SR]

The obtained tubular film was cut to a length of 400 mm as a sample, and measured at 5 places at equal intervals in the width direction and in the longitudinal (circumferential) direction using a resistance measuring device "Hiresta IP-HR probe" manufactured by Mitsubishi Chemical Corporation. Eight points were measured at equal intervals, and a total of 40 points were measured, and the average value of the whole was expressed.

VR is measured after 10 seconds of application of a voltage of 100 V, and SR is measured after 10 seconds of application of a voltage of 500 V.

[Non-volatile matter concentration]

A sample (monomer mixed solution, etc.) is placed in a heat-resistant container such as a metal cup, and accurately weighed, and the sample weight at this time is set to Ag. Put the heat-resistant container with the sample in an electric oven, raise the temperature sequentially at 120°C for 12 minutes, 180°C for 12 minutes, 260°C for 30 minutes and 300°C for 30 minutes, then heat and dry. Let the weight of the obtained solid content (non-volatile matter weight) be Bg. For the same sample, A and B values (n=5) of 5 samples were measured and substituted into the following formula (I) to obtain the non-volatile matter concentration. The average value of these 5 samples was adopted as the non-volatile matter concentration in this invention.

Non-volatile concentration = B/A×100(%) (I)

Example A-1

Dimethyl 2,3,3',4'-biphenyltetracarboxylic acid (reaction product of 1 mole of 2,3,3',4'-biphenyltetracarboxylic dianhydride and 2 moles of methanol, half 716.0 g (2.0 mol) of ester) and 400.0 g (2.0 mol) of 4,4'-diaminodiphenyl ether were mixed at room temperature and uniformly dissolved in 1540 g of NMP solvent. This solution was a stable solution with a non-volatile matter concentration of 34.6% by weight, a solution viscosity of about 250 mPa·s, substantially no polycondensation reaction, and a monomeric state. Hereinafter, it is referred to as "asymmetric monomer solution A".

On the other hand, dimethyl 3,3',4,4'-biphenyltetracarboxylic acid (1 mole of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2 moles of methanol Reactant (half ester) 716.0 g (2.0 moles) and 4,4'-diaminodiphenyl ether 400.0 g (2.0 moles) were mixed at room temperature and uniformly dissolved in 1540 g of NMP solvent. This solution was a stable solution with a non-volatile matter concentration of 34.6% by weight, a solution viscosity of about 250 mPa·s, substantially no polycondensation reaction, and a monomeric state. Hereinafter referred to as "symmetrical monomer solution B".

Then, for the above-mentioned asymmetric monomer solution A and symmetrical monomer solution B, with the respective amount ratios described in EX.1 and EX.2 shown in Table A-1, with EF-351 manufactured by Tohkem Products Co., Ltd.) and 0.037% by weight (with respect to non-volatile matter) were thoroughly mixed together and defoamed. This was used as monomer solution C for molding, and a predetermined amount was taken from each solution, poured into a rotating cylinder, and molded under the following conditions.

Rotating cylinder: A metal cylinder having an inner diameter of 100 mm and a width of 530 mm with a mirror surface attached to the inner surface was placed on two rotating rollers, and arranged so as to be in a state of rotating together with the rotation of the rollers.

Injection amount of monomer solution C for molding: 45.9g

Heating temperature: a far-infrared heater is arranged on the outer surface of the cylinder, and the temperature of the inner surface of the cylinder is controlled at 170°C.

First, 45.9 g of each monomer solution was uniformly poured into the bottom surface of the cylinder while the rotating cylinder was stopped. Then, start to rotate immediately, slowly increase the speed to reach 24rad/s, spread evenly on the whole surface, and start heating. The heating was carried out by gradually raising the temperature to 170° C. while maintaining the rotation, and heating at this temperature for 90 minutes.

After the 90-minute rotation-heating was completed, it was cooled to normal temperature, and the rotating cylinder was detached as it was, and was left still in a hot-air stagnation oven (hot-air furnace), and heating for imidization was started. This heating is also gradually increased to 350°C. Then, after heating at this temperature for 30 minutes, it cooled to normal temperature, and peeled and took out the tubular PI film formed in the inner surface of this cylinder. The results of each example are shown in Table A-2.

Table A-1 EX No. The weight ratio of asymmetric monomer solution A and symmetrical monomer solution B Mole % of Asymmetric Monomer Solution A and Symmetric Monomer Solution B The amount of CB powder relative to 100 parts by weight of raw material monomer (parts by weight) Solution A Solution B Solution A Solution B Example A-1 1 200 200 50 50 0 2 80 320 20 80 0 Comparative Example A-1 3 280 120 70 30 0 4 40 360 10 90 0 5 0 200 0 100 0 6 200 0 100 0 0 Example A-2 7 200 200 50 50 8.33 Comparative Example A-2 8 280 120 70 30 8.33 9 40 360 10 90 8.33

Table A-2 EXNo. Film thickness (μm) Yield strength σ _Y (MPa) Breaking strength σ _cr (MPa) σ _cr /σ _Y VR(Ω·cm) SR(Ω/□) Remark Example A-1 1 85 132.5 147 1.11 2.8×10 ¹⁴ 1.0×10 ¹⁶ 2 85 145 172.5 1.19 ditto ditto Comparative Example A-1 3 85 123.5 123.5 1 ditto ditto 4 - - - - - - brittle, undeterminable 5 - - - - - - brittle, undeterminable 6 85 116 117.5 0.99 2.8×10 ¹⁴ 1.0×10 ¹⁶ Example A-2 7 85 131 144.5 1.1 3.0×10 ¹⁰ 1.4×10 ¹² Comparative Example A-2 8 85 119.5 120 1 4.2×10 ¹⁰ 5.0×10 ¹² 9 - - - - - - brittle, undeterminable

Comparative Example A-1

In addition to mixing the asymmetric monomer solution A and the symmetrical monomer solution B of Example A-1 at the respective ratios described in EX.3 to 6 shown in Table A-1, with Each of molding, imidization, peeling from the rotating cylinder, and taking out was performed under the same conditions as in this example, and measured. The respective results are described in Table A-2.

Example A-2

Using the asymmetric monomer solution A and the symmetrical monomer solution B in Example A-1, with the amount ratio described in EX.7 shown in Table A-1, as in this example, first after uniform mixing, 14.0 g of CB powder (pH 3, particle diameter 23 nm) (8.33 parts by weight relative to 100 parts by weight of the total amount of all monomers) was added thereto, fully mixed and dispersed in a ball mill, and finally defoamed. This was used as a semiconductive monomer solution for molding. The non-volatile matter concentration in this semiconductive monomer solution was 36.8% by weight, and the CB concentration in this non-volatile matter was 9.19% by weight.

Then, 45.9 g was collected from this solution, and it poured into the rotating cylinder similarly to Example A-1, and imidation was performed after shaping|molding on the same conditions. The obtained imidized film was peeled and taken out from the rotating cylinder, and it measured. The results are described in Table A-2.

Comparative Example A-2

Using the asymmetric monomer solution A and the symmetrical monomer solution B of Example A-1, with the respective quantitative ratios described in EX.8 and 9 shown in Table A-1, as in this example, first uniform After mixing, 8.33 parts by weight of CB powder was added thereto in the same manner as in Example A-2, based on 100 parts by weight of the total amount of all monomers, fully mixed and dispersed in a ball mill, and finally defoamed. This was used as a semiconductive monomer solution for molding. The non-volatile matter concentration in this semiconductive monomer solution was 36.8% by weight, and the CB concentration in this non-volatile matter was 9.19% by weight.

Then, 45.9 g was collected from each of the solutions A and B, poured into a rotating cylinder in the same manner as in Example A-1, and molded under the same conditions. After imidization, it was peeled and taken out from the rotating cylinder, and measured. Each result is described in Table A-2.

B. Second invention

Next, the second invention will be described in more detail with reference to comparative examples and examples.

Example B-1

2,3,3',4'-biphenyltetracarboxylic acid dimethyl ester (1 mole of 2,3,3',4'-biphenyltetracarboxylic acid tetracarboxylic dianhydride and 2 moles of methanol material, diester) 358.0g (1.0 mole) and 3,3',4,4'-biphenyltetracarboxylic acid dimethyl ester (1 mole of 3,3',4,4'-biphenyltetracarboxylic acid tetracarboxylate The reactant of carboxylic acid dianhydride and 2 moles of methanol, diester) 358.0 g (1.0 moles) and 4,4'-diaminodiphenyl ether 400.0 g (2.0 moles) were mixed at 60°C and uniformly dissolved in 1674 g Next, the temperature was raised to 100° C. over 1 hr, heated at 100° C. for 1 hr, and then cooled. This solution was an oligomer-like solution having a nonvolatile matter concentration of 32.9% by weight and a number average molecular weight of 2,000. Hereinafter, it is referred to as "oligomer mixed solution A".

Add 71.7 g of carbon black (CB) powder (pH 3, particle diameter 23 nm) and 142.5 g of NMP to 1000 g of the oligomer mixed solution A, mix and disperse fully in a ball mill, and finally defoam. This was used as a semiconductive oligomer solution for molding. The non-volatile matter concentration in the semiconductive oligomer solution was 33.0% by weight, and the CB concentration in the non-volatile matter was 17.89% by weight.

Then, 109 g was collected from this solution, poured into a rotating cylinder, and each was molded under the following conditions.

Rotating cylinder: A metal cylinder having an inner diameter of 175 mm and a width of 540 mm with a mirror surface attached to the inner surface was placed on two rotating rollers, and arranged so as to be in a state of rotating together with the rotation of the rollers.

Heating temperature: a far-infrared heater is arranged on the outer surface of the cylinder, and the temperature of the inner surface of the cylinder is controlled at 120°C.

First, 109 g of the solution was uniformly applied to the inner surface of the cylinder while the cylinder was rotating, and heating was started. Heating was carried out by raising the temperature at 2°C/min to 120°C while maintaining its rotation, and heating at this temperature for 90 minutes.

After the rotation and heating are completed, the rotating cylinder is detached without cooling, and it is left still in the hot air stagnation oven, and the heating for imidization starts. This heating is also gradually increased to 320°C. Then, after heating at this temperature for 30 minutes, it cooled to normal temperature, and peeled and took out the semiconductive tubular PI film formed in the inner surface of this cylinder. In addition, the thickness of the film was 90 μm.

In addition, the so-called "non-volatile matter concentration" in this specification is the value computed as follows. A sample (semiconductive oligomer solution, etc.) is placed in a heat-resistant container such as a metal cup and accurately weighed, and the sample weight at this time is set to Ag. Put the heat-resistant container with the sample in an electric oven, raise the temperature sequentially at 120°C for 12 minutes, 180°C for 12 minutes, 260°C for 30 minutes and 300°C for 30 minutes, then heat and dry. Let the weight of the obtained solid content (non-volatile matter weight) be Bg. For the same sample, the values of A and B of five samples were measured (n=5), and substituted into the following formula (I) to obtain the nonvolatile concentration. The average value of these 5 samples was adopted as the non-volatile matter concentration in this invention.

Non-volatile concentration = B/A×100(%) (I)

Reference example B-1

Dimethyl carboxylate and diaminodiphenyl ether were mixed in the same quantitative ratio as in Example B-1, and the solution dissolved at 60° C. was directly cooled. This solution has a nonvolatile matter concentration of 32.9% by weight and is substantially in a monomeric state. Hereinafter, it is referred to as "monomer solution A".

Add 31.0 g of CB powder (pH 3, particle size 23 nm) and 60.0 g of NMP to 1000 g of the monomer solution A, fully mix and disperse in a ball mill, and finally defoam. This was used as a semiconductive monomer solution for molding. The concentration of non-volatile matter in this semiconductive monomer solution was 33.0% by weight, and the concentration of CB in this non-volatile matter was 8.61% by weight.

Then, 109 g was collected from this solution, and then, heat-molded in the same manner as in Example B-1, and the semiconductive tubular PI film was peeled off and taken out. In addition, the thickness of the film was 92 μm.

Example B-2

2,3,3',4'-biphenyltetracarboxylic acid dimethyl ester (1 mole of 2,3,3',4'-biphenyltetracarboxylic acid tetracarboxylic dianhydride and 2 moles of methanol material, diester) 143.2g (0.4 mol) and 3,3',4,4'-biphenyl tetracarboxylic acid dimethyl ester (1 mole of 3,3',4,4'-biphenyl tetracarboxylic acid tetra The reactant of carboxylic dianhydride and 2 moles of methanol, diester) 572.8g (1.6 moles) and 4,4'-diaminodiphenyl ether 400g (2 moles) were mixed and uniformly dissolved in 1674g of Next, in the NMP solvent, the temperature was raised to 110° C. over 1 hr, heated at 110° C. for 1 hr, and then cooled. This solution was an oligomer-like solution having a nonvolatile matter concentration of 32.9% by weight and a number average molecular weight of 4,000. Hereinafter, it is referred to as "oligomer mixed solution B".

78.9 g of CB powder (pH 3, particle size 23 nm) and 157.1 g of NMP were added to 1000 g of the oligomer mixed solution B, and the mixture was fully mixed and dispersed in a ball mill, and finally defoamed. This was used as a semiconductive oligomer solution for molding. The non-volatile matter concentration in the semiconductive oligomer solution was 33.0% by weight, and the CB concentration in the non-volatile matter was 19.34% by weight.

Then, 109 g was collected from this solution, poured into the rotating cylinder, and thereafter, heat-molded in the same manner as in Example B-1, and the semiconductive tubular PI film was peeled and taken out. In addition, the thickness of the film was 89 μm.

Comparative Example B-1

Dimethyl carboxylate and diaminodiphenyl ether were mixed in the same quantitative ratio as in Example B-1, dissolved at 60°C, then heated to 130°C over 1 hr, heated at 130°C for 1 hr, and then cooled. However, this solution after cooling turned into a turbid gel-like solid and could not be used for molding.

The gel cannot be redissolved even if it is diluted with a solvent. As a result of measuring the imidization ratio of the obtained gel, it was confirmed that about 35% of the imidization reaction proceeded. That is, the applicant considered that because the heating temperature was high and the imidization reaction was excessive, the solubility decreased and the resin component was precipitated.

Test example B-1

Table B-1 shows the film production conditions of Examples B-1 to B-2, Reference Example B-1, and Comparative Example B-1 and the measurement results of resistance values of the obtained films. The average and standard deviation of surface resistivity and volume resistivity in Table B-1 are expressed in logarithmic conversion values.

[number average molecular weight]

The number average molecular weight is measured by the GPC method (solvent: NMP, polyethylene oxide conversion).

[Imidation rate]

Calculated from the ratio of the intensity of the absorption derived from the imide group (1780 cm ^-1 ) and the absorption derived from the benzene ring (1510 cm ^-1 ) in an infrared spectrophotometer. Since the absorption of the benzene ring did not change either in the precursor or after imidization, it was used as a control.

[Measurement of Surface Resistivity (SR) and Volume Resistivity (VR)]

The obtained tubular film was cut to a length of 400 mm as a sample, and measured at three points at equal intervals in the width direction and at three points in the longitudinal (circumferential) direction using a resistance measuring device "Hiresta IP-HR probe" manufactured by Mitsubishi Chemical Corporation. Four points were measured at equal intervals, and a total of 12 points were measured, and the average value of the whole was expressed.

The volume resistivity (VR) was measured after 10 seconds of application of a voltage of 100V, and the surface resistivity (SR) was measured after 10 seconds of application of a voltage of 500V.

Table B-1 heating temperature Number average molecular weight Imidization rate Ratio of asymmetric and symmetric bodies The amount of CB powder in the film film thickness Surface resistance value of film surface side (LogSR) Surface resistance value of film back side Volume resistivity (LogVR) Surface-to-back difference of surface resistivity LogSR-LogVR asymmetric body symmetrical body average average standard deviation average standard deviation average standard deviation Example B-1 100°C 2000 10% 50 50 17.89 90μm 11.77 0.11 11.87 0.09 9.88 0.11 0.10 1.89 Example B-2 110°C 4000 20% 20 80 19.34 89μm 11.93 0.11 12.07 0.13 10.49 0.08 0.14 1.44 Reference example B-1 60℃ 250 0% 50 50 8.61 92μm 11.99 0.30 12.40 0.25 12.10 0.43 0.41 -0.11 Comparative Example B-1 130°C 35% 50 50

The average value and standard deviation of surface resistivity and volume resistivity are logarithmic conversion values

Resistance measurement: 3 points in the belt width direction x 4 points in the circumferential direction = 12 points

Applied voltage: 100V value after 10 seconds

Resistance Measuring Machine: Hiresta IP HR PRO 1 BU

It can be seen from Table B-1 that, compared with the reference example and the comparative example, the standard deviation of the surface resistivity and volume resistivity of the film of the example is very small, that is, the variability is small.

In addition, the film of the example has a very small difference in surface resistivity (logarithmic conversion value) between the front side and the back side of the film compared to the reference example and the comparative example, and has good characteristics as an intermediate transfer belt for a color copier.

In addition, generally speaking, if the heating temperature rise rate in molding is accelerated, the logarithmic conversion value LogSR of the surface resistivity minus the logarithmic conversion value LogVR of the volume resistivity (Log(SR/VR)) will decrease, Therefore, when used as a duplicating tape, there is a problem that charge removal and charging cannot be accurately performed, causing image defects. However, it was found that this value can be maintained at a high value (1.0 to 3.0) by using the oligomer mixed solution, thereby further improving the productivity of the film.

C. The third invention

Next, the third invention will be described in more detail using comparative examples and examples. In addition, hereinafter, 2,3,3',4'-biphenyltetracarboxylic dianhydride is represented by "a-BPDA", and 3,3',4,4'-biphenyltetracarboxylic dianhydride is represented by "s-BPDA". Acid dianhydride. The number average molecular weight is measured by the GPC method (solvent: NMP).

Example C-1

Put 22.8g of methanol and 160g of N-methyl-2-pyrrolidone into 14g of a-BPDA and 56g of s-BPDA (20 mol%: 80 mol%), and react under a nitrogen flow at a water bath temperature of 70°C . Next, after cooling to a water bath temperature of 65°C, 47.6 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred slowly to obtain 300.4 g of a nylon salt-type monomer solution. The solution had a viscosity of 1.8 poise and a nonvolatile matter concentration of 36.3% by weight.

Next, 47.6 g of ODA was added to 448 g of N-methyl-2-pyrrolidone under nitrogen gas flow, and it was kept at 50° C. and stirred to completely dissolve it. The powder which mixed a-BPDA:35g and s-BPDA:35g was gradually added to this solution, and 605.6g of polyamic-acid solutions were obtained. The number average molecular weight of this polyamic-acid solution was 16000, the viscosity was 30 poise, and the nonvolatile matter concentration was 18.0 weight%.

180 g of polyimide precursor solutions obtained by mixing 100 g of the nylon salt type monomer solution and 80 g of the polyamic acid solution were produced. The viscosity was 13 poise, and the nonvolatile matter concentration was 28.2% by weight.

7.5 g of acidic carbon (pH 3.0) and 16.7 g of N-methyl-2-pyrrolidone were added to 150 g of this precursor solution, and carbon black was uniformly dispersed in a ball mill. The masterbatch solution had a non-volatile concentration of 28.6% by weight, a CB concentration in the non-volatile matter of 15.1% by weight, an average particle size of carbon black of 0.28 μm, and a maximum particle size of 0.58 μm. In addition, the average particle diameter of the carbon black after 10 days was 0.28 μm, and the maximum particle diameter was 0.76 μm, showing little change.

In addition, the so-called "non-volatile matter concentration" in this specification is the value calculated as follows. The sample (nylon salt-type monomer solution, etc.) is placed in a heat-resistant container such as a metal cup and accurately weighed, and the sample weight at this time is defined as Ag. Put the heat-resistant container with the sample in an electric oven, raise the temperature sequentially at 120°C for 12 minutes, 180°C for 12 minutes, 260°C for 30 minutes and 300°C for 30 minutes, then heat and dry. Let the weight of the obtained solid content (non-volatile matter weight) be Bg. For the same sample, A and B values (n=5) of 5 samples were measured and substituted into the following formula (I) to obtain the non-volatile matter concentration. The average value of these 5 samples was adopted as the non-volatile matter concentration in this invention.

Non-volatile concentration = B/A×100(%) (I)

Example C-2

Put 22.8g of methanol and 160g of N-methyl-2-pyrrolidone into 35g of a-BPDA and 35g of s-BPDA (50 mol %: 50 mol %), and react at a water bath temperature of 80°C under nitrogen flow . Next, after cooling to a water bath temperature of 65°C, 47.6 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred slowly to obtain 300.4 g of a nylon salt-type monomer solution. The solution had a viscosity of 1.8 poise and a nonvolatile matter concentration of 36.3% by weight.

Next, 47.6 g of ODA was added to 448 g of N-methyl-2-pyrrolidone under nitrogen gas flow, and it was kept at 50° C., stirred and completely dissolved. s-BPDA:70g was gradually added to this solution, and 605.6 g of polyamic-acid solutions were obtained. The polyamic acid solution had a number average molecular weight of 12000, a viscosity of 12 poise, and a nonvolatile matter concentration of 18.0% by weight.

180 g of polyimide precursor solutions obtained by mixing 100 g of the nylon salt type monomer solution and 80 g of the polyamic acid solution were produced. The viscosity was 5.2 poise, and the nonvolatile matter concentration was 28.2% by weight.

7.5 g of acidic carbon (pH 3.0) and 16.7 g of N-methyl-2-pyrrolidone were added to 150 g of this precursor solution, and carbon black was uniformly dispersed in a ball mill. The non-volatile matter concentration of this masterbatch solution was 28.6% by weight, the CB concentration in the non-volatile matter was 15.1% by weight, the average particle size of carbon black was 0.31 μm, and the maximum particle size was 0.77 μm. In addition, the average particle diameter of the carbon black after 10 days was 0.31 μm, and the maximum particle diameter was 0.88 μm, showing little change.

Example C-3

Put 22.8g of methanol and 250g of N-methyl-2-pyrrolidone into 21g of a-BPDA and 49g of s-BPDA (30 mol%: 70 mol%), and react under a nitrogen flow at a water bath temperature of 80°C . Next, after cooling to a water bath temperature of 65°C, 47.6 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred slowly to obtain 390.4 g of a nylon salt-type monomer solution. The solution had a viscosity of 0.7 poise and a nonvolatile matter concentration of 27.9% by weight.

110 g of a polyamide-imide solution (VYLOMAX HR-16NN manufactured by Toyobo Co., Ltd.) (number-average molecular weight: 21,000, solid content: 14% by weight, viscosity: 500 poise) was prepared by mixing 200 g of the nylon salt-type monomer solution. The resulting polyimide precursor solution was 310 g. The viscosity was 18 poise, and the nonvolatile matter concentration was 23.0% by weight.

10.9 g of acidic carbon (pH 3.0) and 25.2 g of N-methyl-2-pyrrolidone were added to 260 g of this precursor solution, and carbon black was uniformly dispersed in a ball mill. The nonvolatile matter concentration of this masterbatch solution was 23.9% by weight, the carbon black concentration in the nonvolatile matter was 15.4% by weight, the average particle diameter of carbon black was 0.215 μm, and the maximum particle diameter was 0.51 μm. In addition, the average particle diameter of the carbon black after 10 days was 0.218 μm, and the maximum particle diameter was 0.58 μm, showing little change.

Reference example C-1

13.5 g of acidic carbon (pH 3.0) and 120 g of an organic solvent (NMP) were added to 200 g of the nylon salt-type monomer prepared in Example C-1, and main dispersion was performed in a ball mill. The viscosity of this solution was 5 poise, the nonvolatile matter concentration was 25.8% by weight, the CB concentration in the nonvolatile matter was 15.7% by weight, the average particle size of carbon black was 0.39 μm, and the maximum particle size was 2.26 μm. Furthermore, the average particle diameter of the carbon black after 10 days was 0.79 μm, and the maximum particle diameter was 7.70 μm, and aggregation of carbon black was confirmed.

Reference example C-2

47.6 g of ODA was added to 450 g of N-methyl-2-pyrrolidone under nitrogen gas flow, and it was kept at 50° C. and stirred to completely dissolve it. s-BPDA:70g was gradually added to this solution, and 567.6 g of polyamic-acid solutions were obtained. The polyamic acid solution had a weight average molecular weight of 5000, a viscosity of 6.6 poise, and a nonvolatile matter concentration of 19.2% by weight. 180 g of a polyimide precursor solution formed by mixing 80 g of this solution and 100 g of the nylon salt-type monomer produced in Example C-2 was prepared, and 9.5 g of acidic carbon (pH 3.0) and an organic solvent (NMP) were added. 120g, the main dispersion is carried out in a ball mill. The viscosity of this solution was 6 poise, the non-volatile matter concentration was 19.8% by weight, the CB concentration in the non-volatile matter was 15.5% by weight, the average particle size of carbon black was 0.26 μm, and the maximum particle size was 0.87 μm. Furthermore, the average particle diameter of the carbon black after 10 days was 0.77 μm, and the maximum particle diameter was 5.10 μm, and aggregation of carbon black was confirmed.

Example C-4 (production of tubular polyimide film by rotational molding method)

Rotate a cylindrical mold with an outer diameter of 300 mm, an inner diameter of 270 mm, and a length of 500 mm at a rotational speed of 100 rpm (10.5 rad/s), and at the same time, uniformly coat the inner surface of the cylindrical mold with a width of 480 mm. Example C-1, C-2 , C-3, the solutions of reference examples C-1 and C-2. The coating thickness was calculated from the nonvolatile matter concentration so that the thickness of the polyimide tape was 100 μm. For solvent evaporation, the temperature was raised to 110° C. over 60 minutes, and then kept at 110° C. for 120 minutes to evaporate the solvent and produce a self-supporting tube.

Next, the tubular product was put into a high-temperature heating furnace in a state attached to the inner surface of a cylindrical mold, heated to 320° C. over 120 minutes, and heated at 320° C. for 60 minutes to perform polyimide conversion. Then, after cooling to normal temperature, the tubular polyimide film was taken out from the mold. The surface state thereof was judged with the naked eye.

Surface resistivity (SR) and volume resistivity (VR) were measured by cutting the obtained polyimide tube into a length of 400 mm as a sample, and using a resistance measuring device "Hiresta IP-HR" manufactured by Mitsubishi Chemical Corporation. probe", measured at 3 locations at equal intervals in the width direction and at 4 locations at equal intervals in the longitudinal (circumferential) direction, a total of 12 locations were measured, and expressed as the overall average value.

The volume resistivity (VR) was measured after 10 seconds of application of a voltage of 100V, and the surface resistivity (SR) was measured after 10 seconds of application of a voltage of 500V.

The assay results are summarized in Table C-1. The average and standard deviation of surface resistivity and volume resistivity in Table C-1 are expressed in logarithmic conversion values. In addition, the CB content in the tube and the thickness of the tube are also shown in Table C-1.

Table C-1 Example C-1 Example C-2 Example C-3 Reference example C-1 Reference example C-2 surface condition good good good Condensate Condensate Surface resistivity Log(Ω/□) average 10.28 10.51 10.34 7.01 8.84 standard deviation 0.15 0.07 0.03 0.05 0.10 Back surface resistivity Log(Ω/□) average 10.31 10.53 10.37 8.83 10.28 standard deviation 0.14 0.07 0.03 0.61 0.14 Volume resistivity Log(Ω·cm) average 8.63 8.63 8.92 9.64 8.7 standard deviation 0.07 0.04 0.06 0.26 0.2 (Back-Surface) Resistivity index 0.02 0.02 0.03 1.82 1.44 (surface-volume) resistivity index 1.66 1.88 1.42 -2.62 0.14 CB content (weight%) 15.1 15.1 15.4 15.7 15.5 Average thickness (μm) 100 100 100 100 100

It can be seen from Table C-1 that, compared with the reference example, the standard deviation of the surface resistivity and volume resistivity of the tubular objects of the examples is very small, that is, the variability is small.

In addition, the tubes of the examples have very small difference in surface resistivity (logarithmic conversion value) between the front side and the back side of the tubes compared to the reference examples, and have good characteristics as electrophotographic transfer tapes.

In addition, generally speaking, when the heating rate in molding is accelerated, the logarithmically converted value LogSR of the surface resistivity minus the logarithmically converted value LogVR of the volume resistivity (Log(SR/VR)) decreases, Therefore, when used as a duplicating tape, there is a problem that charge removal and charging cannot be accurately performed, causing image defects. However, it was found that this value can be maintained at a high value (1.0 to 2.0) by using the semiconductive PI precursor composition of the present invention.

On the other hand, in the reference example, the surface resistivity of the tube was smaller than the value of the back surface resistivity, and the applicant thought that the carbon black concentration gradient occurred in the thickness direction of the tube. As a result, it can be seen that the value of the volume resistivity increases, and the variability also increases.

D. The fourth invention

Next, the fourth invention will be described in more detail using comparative examples and examples. Hereinafter, "a-BPDA" represents 2,3,3',4'-biphenyltetracarboxylic dianhydride, and "s-BPDA" represents 3,3',4,4'-biphenyltetracarboxylic anhydride.

Example D-1

Add 27g of acidic carbon (pH 3.0, volatile matter 14.5%) into 153g of organic polar solvent N-methyl-2-pyrrolidone, and perform main dispersion in a ball mill after pre-dispersion. The average particle size of carbon black was 0.29 μm, and the maximum particle size was 0.55 μm. Next, 14 g of a-BPDA, 56 g of s-BPDA, and 22.8 g of methanol were thrown into 120 g of this solution, and reacted at a water bath temperature of 60° C. under nitrogen flow.

Next, after cooling to a water bath temperature of 50°C, add 47.6g of 4,4'-diaminodiphenyl ether (ODA), and stir slowly to obtain a carbon black-dispersed high-concentration polyimide precursor composed of monomers Composition 260g. The viscosity of this solution was 32 poise, the non-volatile matter concentration was 48.9% by weight, the CB concentration in the non-volatile matter was 14.2% by weight, the average particle size of carbon black was 0.29 μm, and the maximum particle size was 0.58 μm. In addition, the average particle size of the carbon black after 10 days was 0.31 μm, and the maximum particle size was 0.67 μm, showing little change.

In addition, the so-called "non-volatile matter concentration" in this specification is the value calculated as follows. A sample (such as a carbon black-dispersed high-concentration polyimide precursor composition) is placed in a heat-resistant container such as a metal cup, and accurately weighed, and the sample weight at this time is defined as Ag. Put the heat-resistant container with the sample in an electric oven, raise the temperature sequentially at 120°C for 12 minutes, 180°C for 12 minutes, 260°C for 30 minutes and 300°C for 30 minutes, then heat and dry. Let the weight of the obtained solid content (non-volatile matter weight) be Bg. For the same sample, A and B values (n=5) of 5 samples were measured and substituted into the following formula (I) to obtain the non-volatile matter concentration. The average value of these 5 samples was adopted as the non-volatile matter concentration in this invention.

Non-volatile concentration = B/A×100(%) (I)

Example D-2

Add 10 g of furnace black (pH 9.0, volatile matter 1.5%) into 120 g of organic polar solvent N-methyl-2-pyrrolidone, and perform main dispersion in a ball mill after pre-dispersion. The average particle diameter of carbon black was 0.67 μm, and the maximum particle diameter was 3.92 μm. Next, 35 g of a-BPDA, 35 g of s-BPDA, and 22.8 g of methanol were thrown into 125 g of this solution, and reacted at a water bath temperature of 70° C. under nitrogen flow. Next, after cooling to a water bath temperature of 50°C, add 47.6g of 4,4'-diaminodiphenyl ether (ODA), and stir slowly to obtain a carbon black dispersed high-concentration polyimide precursor formed from monomers Composition 265g. The viscosity of this solution was 12 poise, the non-volatile matter concentration was 44.7% by weight, the CB concentration in the non-volatile matter was 8.2% by weight, the average particle size of carbon black was 0.77 μm, and the maximum particle size was 3.92 μm. Furthermore, the average particle diameter of the carbon black after 10 days was 0.77 μm, and the maximum particle diameter was 4.47 μm, showing little change.

Comparative example D-1

Add 20g of acid carbon (pH3.0, volatile matter 14.5%) into 600g of high molecular weight polyamic acid solution (viscosity is 50 poise, non-volatile concentration is 18.0% by weight) synthesized by s-BPDA and ODA , the main dispersion is carried out in a ball mill, the viscosity of the solution is high, and it becomes a gel. Next, 300 g of an organic solution (NMP) was added to this solution for redispersion. The viscosity of this solution was 8 poise, the non-volatile matter concentration was 13.9% by weight, the CB concentration in the non-volatile matter was 15.6% by weight, the average particle size of carbon black was 0.32 μm, and the maximum particle size was 0.77 μm. Furthermore, the average particle size of the carbon black after 10 days was 0.32 μm, and the maximum particle size was 0.77 μm, showing little change.

Reference example D-1

Put 22.8g of methanol and 160g of N-methyl-2-pyrrolidone into 35g of a-BPDA and 35g of s-BPDA (50 mol%: 50 mol%), and react under the flow of nitrogen at a water bath temperature of 70°C . Next, after cooling to a water bath temperature of 60°C, 47.6 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred slowly to obtain 300.4 g of a nylon salt-type monomer solution. The solution had a viscosity of 1.8 poise and a nonvolatile matter concentration of 36.3% by weight. To this solution, 16.5 g of acidic carbon (pH 3.0, 14.5% volatile matter) and 140 g of an organic solvent (NMP) were added, and main dispersion was performed in a ball mill. The viscosity of this solution was 5 poise, the non-volatile matter concentration was 27.5% by weight, the CB concentration in the non-volatile matter was 12.3% by weight, the average particle size of carbon black was 0.47 μm, and the maximum particle size was 1.73 μm. Furthermore, the average particle diameter of the carbon black after 10 days was 0.78 μm, and the maximum particle diameter was 5.12 μm, and aggregation of carbon black was confirmed.

Example D-3 (manufacturing of tubular polyimide film by rotational molding)

Rotate a cylindrical mold with an outer diameter of 300 mm, an inner diameter of 270 mm, and a length of 500 mm at a rotational speed of 100 rpm (10.5 rad/s), and simultaneously coat the inner surface of the cylindrical mold with a width of 480 mm. Embodiment D-1, D-2 And the solutions of Comparative Example D-1 and Reference Example D-1. The coating thickness was calculated from the nonvolatile matter concentration so that the thickness of the polyimide tape was 100 μm. The volatilization of the solvent was carried out by raising the temperature to 100° C. for 60 minutes, then observing the volatilization of the solvent at 100° C. with the naked eye, and measuring the time required to complete the volatilization of the solvent.

Next, the tubular product was put into a high-temperature heating furnace in a state attached to the inner surface of a cylindrical mold, heated to 320° C. over 120 minutes, and heated at 320° C. for 60 minutes to perform polyimide conversion. Then, after cooling to normal temperature, the tubular polyimide film was taken out from the mold. The above results are shown in Table D-1. In addition, the CB content in the tube and the thickness of the tube film are also shown in Table D-1.

In addition, the surface resistivity (SR) was measured by cutting the obtained tubular polyimide film to a length of 400 mm as a sample, and using a resistance measuring device "Hiresta IP-HR probe" manufactured by Mitsubishi Chemical Corporation, measured Three points were measured at equal intervals above and four points were measured at equal intervals in the longitudinal (circumferential) direction, a total of 12 points were measured, and the overall average value was expressed. The surface resistivity (SR) was measured after 10 seconds of applying a voltage of 500V.

Table D-1 Forming solution The time required for the solvent to evaporate surface condition Surface resistivity (Ω/□) CB content in tube (wt%) Thickness of tube (μm) Example D-1 45 minutes good 2.5×10 ¹⁰ 14.2 94～102 Example D-2 60 minutes good 5.0×10 ⁷ 8.1 96～103 Comparative example D-1 170 minutes good 2.0×10 ¹⁰ 15.6 88～102 Reference example D-1 110 minutes carbon condensate 2.0×10 ⁶ 12.3 95～104

In the conventional method (comparative example), the non-volatile matter concentration of the molding raw material is low, and it takes a lot of time to volatilize a large amount of organic polar solvent, and the production efficiency is very poor. In addition, in the method of adding and dispersing CB to a monomer solution or the like, the reaction of the monomer solution proceeds due to heat generated during dispersion, and the solution state is unstable.

Effect of Invention

The tubular PI film of the present invention can easily, efficiently, and economically manufacture a high-quality non-conductive or semiconductive endless (no connecting seam) tubular polyimide film.

Specifically, according to the first invention, a direct endless tubular PI film can be obtained by combining a polyimide monomer raw material composed of a specific composition and a rotational molding method. In addition, compared with the current fabrication method of endless tubular PI membrane via polyamic acid, the time is greatly shortened. In addition, due to the greatly rationalized process management, it is possible to obtain a more stable high-quality tubular PI film while improving productivity. The obtained endless tubular PI film can be used in various applications. In particular, the semiconductive endless tubular film can be more suitably used as an electrophotographic intermediate transfer tape for color printers, color copiers, etc., for example.

The semiconductive tubular PI film of the second invention has a homogeneous film because it uses an aromatic amic acid oligomer obtained by polycondensing a predetermined aromatic tetracarboxylic acid component and an aromatic diamine component as a molding material. resistivity. That is, the semiconductive tubular PI film of the present invention has the following excellent characteristics: the variability of surface resistivity and volume resistivity is small, the difference in surface resistivity (logarithmic conversion value) between the surface of the film surface and the back surface is small, and the surface resistance The value obtained by subtracting the logarithmic conversion value LogVR of the volume resistivity from the logarithmic conversion value LogSR of the resistivity can be maintained at a high value (1.0 to 3.0). Therefore, the semiconductive tubular PI film of the present invention can be suitably used, for example, as an intermediate transfer belt used in a color copier or the like, and can perform excellent image processing because it can properly remove and charge charges.

The semiconductive tubular PI-type film of the third invention, because carbon black is uniformly dispersed in a mixed solution composed of a nylon salt type monomer solution and a high molecular weight polyimide precursor solution or a high molecular weight polyamideimide solution The semiconductive polyimide-based precursor composition obtained in is used as a molding raw material, so it has a homogeneous resistivity. That is, the semiconductive tubular PI-based film of the present invention has the following excellent characteristics: the variability of surface resistivity and volume resistivity is small, and the difference in surface resistivity (logarithmic conversion value) between the surface and the back of the film is small. Therefore, the semiconductive tubular PI-based film of the present invention can be suitably used, for example, as an intermediate transfer belt in a color electrophotography system, and since it can properly remove and charge charges, it can perform excellent image processing.

In the semiconductive high-concentration PI precursor composition of the fourth invention, the CB powder is uniformly dispersed, and the storage stability of the uniformly dispersed CB powder is very high. Furthermore, a conductive tubular PI film obtained by rotationally molding a semiconductive PI precursor composition using the same was endowed with conductivity having a very stable and uniform resistivity in the thickness direction. That is, when used as an electrophotographic intermediate transfer belt used in, for example, color printers and color copiers, etc., excellent image processing can be performed because electric charges can be properly neutralized and charged. In addition, the semiconductive high-concentration PI precursor composition of the present invention can increase the non-volatile matter concentration to about 35 to 60% by weight because the monomer as a molding raw material is dissolved in the carbon black dispersion. Therefore, using the semiconductive high-concentration PI precursor composition of the present invention, a thicker film can be easily produced, and since the amount of solvent used is small, the cost can be suppressed, and the solvent can be evaporated and removed more easily.

Claims (32)

1. an endless tubular polyimide film is characterized in that,

Constitute by polyimide, this polyimide is that the aromatic tetracarboxylic acid's composition more than 2 kinds that the mixture by 85～45 moles of % of 15～55 moles of % of asymmetry aromatic tetracarboxylic acid composition and symmetry aromatic tetracarboxylic acid composition constitutes becomes branch to form with aromatic diamine

Its yield strength (σ _Y) be more than the 120MPa, the ratio (σ of breaking tenacity and yield strength _Cr/ σ _Y) be more than 1.10.

2. a semi-conductivity endless tubular polyimide film is characterized in that,

Disperse black carbon forms in aromatic tetracarboxylic acid's composition more than 2 kinds that the mixture by 15～55 moles of % of asymmetry aromatic tetracarboxylic acid composition and 85～45 moles of % of symmetry aromatic tetracarboxylic acid composition constitutes and the formed polyimide of aromatic diamine composition, and its surface resistivity is 10 ³～10 ¹⁵Ω/.

3. semi-conductivity endless tubular polyimide film as claimed in claim 2, it is characterized in that, the standard deviation of the logarithm conversion value of surface resistivity is in 0.2, the standard deviation of the logarithm conversion value of volume specific resistance is in 0.2, and the difference of the logarithm conversion value of surface resistivity and the logarithm conversion value of back side resistivity is in 0.4.

4. the manufacture method of an endless tubular polyimide film is characterized in that,

Aromatic tetracarboxylic acid's composition that will be made of asymmetry aromatic tetracarboxylic acid or 15～55 moles of % of its ester and symmetry aromatic tetracarboxylic acid or 85～45 moles of % of its ester and aromatic diamine composition mix the formed mixing solutions that is essentially free state with equimolar amount roughly, be configured as pipe with the spinning-shaping method, carry out heat treated, imidization.

5. the manufacture method of a semi-conductivity endless tubular polyimide film is characterized in that,

The aromatic tetracarboxylic acid's composition that constitutes by asymmetry aromatic tetracarboxylic acid or 15～55 moles of % of its ester and symmetry aromatic tetracarboxylic acid or 85～45 moles of % of its ester and aromatic diamine composition with the mixing solutions that is essentially free state that roughly equimolar amount mixes in, total with respect to aromatic tetracarboxylic acid's composition and aromatic diamine composition is measured 100 weight parts, the carbon black that disperses 1～35 weight part, the monomer mixture solution of formed semi-conductivity is configured as pipe with the spinning-shaping method, carry out heat treated, imidization.

6. semi-conductivity endless tubular polyimide film by the intermediate duplication band of the electrofax mode that is used for of the described manufacture method manufacturing of claim 5.

7. a semi-conductivity aromatic amides acid composition is characterized in that,

Contain by the aromatic tetracarboxylic acid's composition more than 2 kinds and aromatic diamine and carry out aromatic amides acid oligomer, carbon black and the organic polar solvent that polycondensation was obtained with equimolar amount roughly.

8. semi-conductivity aromatic amides acid composition as claimed in claim 7, it is characterized in that, described aromatic amides acid oligomer is to carry out the aromatic amides acid oligomer that polycondensation was obtained under the temperature in organic polar solvent, below about 80 ℃ of equimolar amount roughly by the aromatic tetracarboxylic acid's dianhydride more than 2 kinds and aromatic diamine.

9. semi-conductivity aromatic amides acid composition as claimed in claim 8, it is characterized in that, aromatic tetracarboxylic acid's dianhydride more than 2 kinds is by 15～55 moles of % of asymmetry aromatic tetracarboxylic acid dianhydride and 85～45 moles of mixtures that % constituted of symmetry aromatic tetracarboxylic acid dianhydride.

10. semi-conductivity aromatic amides acid composition as claimed in claim 7, it is characterized in that, described aromatic amides acid oligomer is to carry out the aromatic amides acid oligomer that polycondensation was obtained by the aromatic tetracarboxylic acid's diester more than 2 kinds and aromatic diamine with equimolar amount roughly in organic polar solvent, under the temperature about 90～120 ℃.

11. semi-conductivity aromatic amides acid composition as claimed in claim 10, it is characterized in that, aromatic tetracarboxylic acid's diester more than 2 kinds is by 15～55 moles of % of asymmetry aromatic tetracarboxylic acid diester and 85～45 moles of mixtures that % constituted of symmetry aromatic tetracarboxylic acid diester.

12. semi-conductivity aromatic amides acid composition as claimed in claim 7 is characterized in that the number-average molecular weight of described aromatic amides acid oligomer is about 1000～7000.

13. semi-conductivity aromatic amides acid composition as claimed in claim 7 is characterized in that, measures 100 weight parts with respect to the total of aromatic tetracarboxylic acid's composition and organic diamine, the sooty use level is about 3～30 weight parts.

14. the manufacture method of a semi-conductivity endless tubular polyimide film is characterized in that, the described semi-conductivity aromatic amides of claim 7 acid composition is rotated shaping, heat treated.

15. semi-conductivity endless tubular polyimide film by the intermediate duplication band of the electrofax mode that is used for of the described manufacture method manufacturing of claim 14.

16. the manufacture method of a semi-conductivity aromatic amides acid composition is characterized in that,

In organic polar solvent, aromatic tetracarboxylic acid's composition more than 2 kinds and aromatic diamine carry out the part polycondensation with equimolar amount roughly, become aromatic amides acid oligomer solution, with this aromatic amides acid oligomer solution and conductive carbon black powder uniform mixing.

17. a semiconductive polyimide class precursor composition is characterized in that,

Aromatic tetracarboxylic acid's diester more than 2 kinds and aromatic diamine are being dissolved in the nylon salt type monomer solution that forms in the organic polar solvent with equimolar amount roughly, mix high-molecular weight polyimide precursor solution or high-molecular weight polyamidoimide solution, the modulation mixing solutions is dispersed in carbon black in this mixing solutions.

18. semiconductive polyimide class precursor composition as claimed in claim 17, it is characterized in that, aromatic tetracarboxylic acid's diester more than 2 kinds is by 10～55 moles of % of asymmetry aromatic tetracarboxylic acid diester and 90～45 moles of mixtures that % constituted of symmetry aromatic tetracarboxylic acid diester.

19. semiconductive polyimide class precursor composition as claimed in claim 17, it is characterized in that, aromatic tetracarboxylic acid's diester more than 2 kinds, be by 2,3,3 ' of asymmetry, 10～55 moles of % of 4 '-biphenyltetracarboxyacid acid diester and symmetric 3,3 ', 4,90～45 moles of mixtures that % constituted of 4 '-biphenyltetracarboxyacid acid diester.

20. semiconductive polyimide class precursor composition as claimed in claim 17, it is characterized in that, the high-molecular weight polyimide precursor solution is that number-average molecular weight is the polyamic acid solution more than 10000, and high-molecular weight polyamidoimide solution is that number-average molecular weight is the polyamidoimide solution more than 10000.

21. semiconductive polyimide class precursor composition as claimed in claim 20, it is characterized in that, described number-average molecular weight is the polyamic acid solution more than 10000, reacts manufacturing by biphenyl tetracarboxylic dianhydride and diaminodiphenyl oxide with equimolar amount roughly in organic polar solvent.

22. semiconductive polyimide class precursor composition as claimed in claim 20, it is characterized in that, described number-average molecular weight is the polyamidoimide solution more than 10000, reacts manufacturing by trimellitic acid 1,2-anhydride and the formed acid anhydrides of benzophenone tetracarboxylic dianhydride and aromatic isocyanate with equimolar amount roughly in organic polar solvent.

23. the manufacture method of a semi-conductivity endless tubular polyimide class film is characterized in that, the described semiconductive polyimide class of claim 17 precursor composition is configured as pipe with the spinning-shaping method, carries out heat treated, imidization.

24. the surface resistivity by the described manufacture method manufacturing of claim 23 is 10 ⁷～10 ¹⁴Ω/, be used for the semi-conductivity endless tubular polyimide class film of the intermediate duplication band of electrofax mode.

25. the manufacture method of a semiconductive polyimide class precursor composition, it is characterized in that, aromatic tetracarboxylic acid's diester more than 2 kinds and aromatic diamine are being dissolved in the nylon salt type monomer solution that forms in the organic polar solvent with equimolar amount roughly, mix high-molecular weight polyimide precursor solution or high-molecular weight polyamidoimide solution, the modulation mixing solutions is dispersed in carbon black in this mixing solutions.

26. the manufacture method of a semi-conductivity high density polyimide precursor composition, it is characterized in that, carbon black is being dispersed in the carbon black dispersion liquid that forms in the organic polar solvent, with dissolving aromatic tetracarboxylic acid's diester of equimolar amount roughly and aromatic diamine.

27. the manufacture method of semi-conductivity high density polyimide precursor composition as claimed in claim 26, it is characterized in that, aromatic tetracarboxylic acid's diester is by 10～55 moles of % of asymmetry aromatic tetracarboxylic acid diester and 90～45 moles of mixtures that % constituted of symmetry aromatic tetracarboxylic acid diester.

28. the manufacture method of semi-conductivity high density polyimide precursor composition as claimed in claim 26, it is characterized in that, aromatic tetracarboxylic acid's diester, be by 2,3,3 ' of asymmetry, 10～55 moles of % of 4 '-biphenyltetracarboxyacid acid diester and symmetric 3,3 ', 4,90～45 moles of mixtures that % constituted of 4 '-biphenyltetracarboxyacid acid diester.

29. the manufacture method of semi-conductivity high density polyimide precursor composition as claimed in claim 26 is characterized in that, measures 100 weight parts with respect to the total of aromatic tetracarboxylic acid's diester and aromatic diamine, carbon black is about 5～35 weight parts.

30. semi-conductivity high density polyimide precursor composition by the described manufacture method manufacturing of claim 26.

31. the manufacture method of a semi-conductivity endless tubular polyimide film is characterized in that, the described semi-conductivity high density of claim 30 polyimide precursor composition is configured as pipe with the spinning-shaping method, carries out heat treated, imidization.

32. the surface resistivity by the described manufacture method manufacturing of claim 31 is 10 ⁷～10 ¹⁴The semi-conductivity endless tubular polyimide film of the intermediate duplication band of the electrofax mode that is used for of Ω/.