TW202039636A - Polyimide film - Google Patents

Abstract

This polyimide film has an elastic modulus (E'RT) of 3.0*10<SP>9</SP> Pa or more at 30 DEG C and an elastic modulus (GN 0) of less than 1.5*10<SP>7</SP> Pa in a rubbery flat area thereof. Provided is a polyimide film having both high surface hardness and bending resistance. The elastic modulus (E'RT) at 30 DEG C is preferably 3.5*10<SP>9</SP> Pa or more, and more preferably 4.0*10<SP>9</SP> Pa or more. It is preferable to contain an alicyclic structure in a tetracarboxylic acid residue that constitutes a polyimide included in the polyimide film.

Description

Polyimide film

The present invention relates to a polyimide film with high surface hardness and bending resistance.

In recent years, as a variety of device applications, materials with heat resistance, light transmittance, high elastic modulus, and flexibility have been sought.

For the above applications, for example, it is known that aromatic polyimines (such as "Kapton" manufactured by DuPont) are lighter and softer polyimines with higher heat resistance. However, aromatic polyimine is brown and cannot be used for applications requiring high light transmittance.

Therefore, a polyimide exhibiting high light transmittance has been developed (Patent Document 1). Patent Document 1 has a description related to heat resistance. However, in Patent Document 1, research on surface hardness and bending resistance has not been sufficiently conducted.

The rubber-like flat area in the dynamic viscoelasticity measurement of polyimide is described in Patent Document 2. Patent Document 2 shows that by introducing isocyanate as a crosslinking agent into polyimide, as a thermal behavior in dynamic viscoelasticity measurement, the decline of the decline curve becomes gentle. However, Patent Document 2 does not describe the relationship between the elastic modulus (G _N ⁰ ) of the rubber-like flat region and the surface hardness or bending resistance at all.

Patent Document 1: International Publication No. 2011/099518 Patent Document 2: Japanese Patent Laid-Open No. 2004-339363

The subject of the present invention is to provide a polyimide film with high surface hardness and bending resistance.

The inventors found that the modulus of elasticity (E' _RT ) at 30° C. is above a specific value and the modulus of elasticity (G _N ⁰ ) of the rubber-like flat area does not reach the specific value. Surface hardness and bending resistance characteristics, thus completing the present invention.

That is, the present invention has the following contents as the gist.

[1] A polyimide film whose elastic modulus (E' _RT ) at 30°C is 3.0×10 ⁹ Pa or more, and the elastic modulus (G _N ⁰ ) of the rubber-like flat area is less than 1.5×10 ⁷ Pa. [2] The polyimide film described in [1] has an elastic modulus (E' _RT ) at 30° C. of 3.5×10 ⁹ Pa or more. [3] The polyimide film as described in [1] or [2], which has an elastic modulus (E' _RT ) at 30° C. of 4.0×10 ⁹ Pa or more. [4] The polyimide film according to any one of [1] to [3], wherein the tetracarboxylic acid residue constituting the polyimide contained in the polyimide film includes an alicyclic structure . [5] The polyimide film as described in any one of [1] to [4], wherein the polyimide film has a film thickness of 1 μm or more and 300 μm or less. [6] The polyimide film as described in any one of [1] to [5], which is obtained by a casting method. [7] A laminate having a hard coat layer on the surface of the polyimide film described in any one of [1] to [6]. [8] The laminate according to [7], wherein the thickness of the hard coat layer is 50 μm or more and 200 μm or less. [Effects of Invention]

According to the present invention, a polyimide film having both high surface hardness and bending resistance can be provided.

Hereinafter, embodiments of the present invention will be described in detail. The things, methods, etc. exemplified below are examples (representative examples) of the embodiments of the present invention, and the present invention is not limited to these contents as long as it does not deviate from the gist.

The polyimide of the present invention contains an imine ring in the main chain, and contains at least one selected from the group consisting of polyamide, polyamide, and polyimide.

In the present invention, "modulus of elasticity" refers to "modulus of elasticity".

The polyimide film of the present invention is characterized in that the elastic modulus (E' _RT ) at 30°C is 3.0×10 ⁹ Pa or more, and the elastic modulus (G _N ⁰ ) of the rubber-like flat area (hereinafter, sometimes referred to as Is "G _N ⁰ ") less than 1.5×10 ⁷ Pa.

[Mechanism] As the polyimide film of the present invention by the elastic modulus (E _'RT) at 30 deg.] C of not less than a certain value, the elastic modulus (G _N ⁰⁾ less than a certain value rubbery flat area, and The reasons for exhibiting the effects of both high surface hardness and bending resistance include the following reasons.

As shown in Fig. 1, G _N ^{0 is} generally represented by the following formula. G _N ⁰ =ρRT/Me =ρRT/MvNv Here, ρ, Me, Mv, Nv, R, and T are as follows. ρ: Density of the melt Me: Molecular weight between cross-linking points Mv: Molecular weight of repeating unit Nv: Number of bonds between cross-linking points T: Temperature R: Gas constant Also, it is reported that the more flexible polymer chains are Then the smaller the Nv, the larger the Me and the smaller the G _N ⁰ . Furthermore, when G _N ⁰ is observed in multiple stages, it is set to the highest value of the elastic modulus observed in the rubber-like flat area.

G _N ⁰ is also regarded as an indicator of molecular cross-linking. If molecular cross-linking increases, G _N ⁰ tends to increase. However, according to the research of the present inventors, it is known that when stress is applied from the outside at this time, it is difficult to disperse the force, and the stress is applied locally, which deteriorates the bending resistance. On the other hand, the more rigid the polyimide, the higher the planarity of the molecular chain, the stronger and tougher it is, so it can withstand stress, and therefore tends to have characteristics such as improved bending resistance. In general polymers, the elastic modulus increases when the cross-linking of molecules is increased, but in polyimide, if a structure such as molecular cross-linking is adopted, the rigidity may be lost and the performance may be reduced. In the present invention, by making the modulus of elasticity (E' _RT ) at 30°C higher than a specific value, and designing the modulus of elasticity (G _N ⁰ ) of the rubber-like flat area to be lower, the molecular The cross-linking, as a structure with high planarity, arranges molecular chains on the surface to achieve both high surface hardness and bending resistance.

In order to have both the elastic modulus (E' _RT ) at 30°C and the elastic modulus (G _N ⁰ ) of the rubber-like flat area in the present invention, it is only necessary to design the molecular structure of polyimide as follows, for example, The tetracarboxylic acid residue of the polyimide may be introduced into the alicyclic structure. In addition, _E'RT and G _N ⁰ can also be controlled by film forming conditions. For example, it is also possible to increase the temperature during film formation to above the Tg (glass transition temperature) of the polyimide to make it into an amorphous state, and then slow down the cooling rate to promote molecular chain alignment, which has both high Surface hardness and bending resistance.

[The modulus of elasticity of the polyimide film] The modulus of elasticity of the polyimide film of the present invention can be measured by viscoelasticity measurement. Polyimide film of the present invention the elastic modulus (E _'RT) at 30 deg.] C of not less than 3.0 × 10 ⁹ Pa, preferably not less than 3.5 × 10 ⁹ Pa, more preferably not less than 4.0 × 10 ⁹ Pa. On the other hand, the polyimide film of the present invention is the elastic modulus (E _'RT) at 30 deg.] C of preferably 8.0 × 10 ⁹ Pa or less, more preferably 7.5 × 10 ⁹ Pa or less, further preferably 7.0 ×10 ⁹ Pa or less. When _E'RT is in the above range, a balanced physical performance can be achieved to have both high surface hardness and bending resistance.

The elastic modulus (G _N ⁰ ) of the rubber-like flat area of the polyimide film of the present invention is less than 1.5×10 ⁷ Pa, preferably 1.2×10 ⁷ Pa or less, more preferably 1.0×10 ⁷ Pa or less, It is more preferably 9.0×10 ⁶ Pa or less, particularly preferably 8.5×10 ⁶ Pa or less, and most preferably 8.0×10 ⁶ Pa or less. When G _N ^{0 does} not reach the above upper limit, a polyimide film that can have both high surface hardness and bending resistance can be obtained. On the other hand, from the viewpoint of heat resistance, as long as rubber-like flat areas are observed, the lower limit of the elastic modulus (G _N ⁰ ) of the rubber-like flat areas of the polyimide film of the present invention is not particularly limited. The limitation is, for example, 1.0×10 ⁴ Pa or more.

The method of viscoelasticity measurement (dynamic viscoelasticity measurement) is as shown in the item of the following examples. The rubbery flat area is observed in a temperature area exceeding the glass transition temperature (Tg) of the polyimide.

[Polyimine constituting polyimide film] Hereinafter, a preferable aspect of the polyimide (hereinafter, sometimes referred to as the "polyimide of the present invention") constituting the polyimide film of the present invention will be described.

＜The imidization rate of polyimide＞ The imidization rate of the polyimide of the present invention is not particularly limited, and is preferably 70% or more, more preferably 80% or more, and still more preferably 85% or more. The upper limit of the imidization rate is 100% or less. When the imidization ratio is in this range, the dehydration caused by ring closure of the imidine during molding tends to be reduced, and a molded body with fewer voids tends to be obtained, which is preferable. The imidization rate indicates the ratio of the imidine bond in the main chain of the polyimide. It can be achieved by conventional and well-known methods, such as NMR (nuclear magnetic resonance, nuclear magnetic resonance) method, IR (infrared radiation, infrared radiation). Radiation) method, titration method, etc.

＜Structure of polyimide＞ The structure of the polyimide of the present invention is not particularly limited. It has units derived from tetracarboxylic dianhydride (tetracarboxylic acid residues) and units derived from diamine compounds and/or diisocyanate compounds (diamine residues). base).

Polyimide of the present invention contained in the tetracarboxylic acid residue and a diamine residue polyimide-based film to obtain the elastic modulus (E _'RT) at 30 deg.] C and the rubbery region of the flat The type of elastic modulus (G _N ⁰ ) that satisfies the conditions of the present invention is selected, and the content ratio is set.

<Unit derived from tetracarboxylic dianhydride (tetracarboxylic acid residue)> The tetracarboxylic dianhydride which derives the tetracarboxylic acid residue contained in the polyimide of the present invention is not particularly limited. Examples of the tetracarboxylic dianhydride include: aliphatic tetracarboxylic dianhydride (aliphatic tetracarboxylic dianhydride includes alicyclic tetracarboxylic dianhydride and chain aliphatic tetracarboxylic dianhydride), aromatic tetracarboxylic dianhydride Carboxylic dianhydride and so on. These tetracarboxylic dianhydrides may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

(Alicyclic tetracarboxylic dianhydride) As alicyclic tetracarboxylic dianhydride, for example, 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride, 1,2,3,4 -Cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3, 4-Tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1, 2-Dicarboxylic anhydride, tricyclo[6.4.0.0 ^2,7 ]dodecane-1,8:2,7-tetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3, 5,6-tetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, etc. Among them, in order to have a tendency to improve the manufacturing stability, those having an alicyclic structure with 5 or more members are preferable, and those having an alicyclic structure with 6 or more members are more preferable.

(Chain aliphatic tetracarboxylic dianhydride) As the chain aliphatic tetracarboxylic dianhydride, for example, ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, mesobutane-1,2,3,4-tetracarboxylic dianhydride may be mentioned. Anhydride etc.

(Aromatic tetracarboxylic dianhydride) Examples of the aromatic tetracarboxylic dianhydride include: tetracarboxylic dianhydride having one aromatic ring in one molecule, tetracarboxylic dianhydride having two or more independent aromatic rings in one molecule, and tetracarboxylic dianhydride in one molecule Tetracarboxylic dianhydride with condensed aromatic ring, etc.

Among them, in order to easily control the viscosity during manufacture, improve solvent solubility, or improve the flexibility of the coating film, it is preferable to have a tetracarboxylic dianhydride having one aromatic ring in one molecule or The tetracarboxylic dianhydride with two or more independent aromatic rings is particularly preferred as the tetracarboxylic dianhydride with two or more independent aromatic rings in one molecule.

Examples of the tetracarboxylic dianhydride having one aromatic ring in one molecule include pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, and the like.

Examples of the tetracarboxylic dianhydride having two or more independent aromatic rings in one molecule include 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3- Dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2-bis(3, 4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 4 ,4-(terephthalic acid) diphthalic anhydride, 4,4-(isophthalic acid) diphthalic anhydride, 2,2',6,6'-biphenyl tetrakis Carboxylic dianhydride and so on.

Examples of the tetracarboxylic dianhydride having a condensed aromatic ring in one molecule include: 1,2,5,6-naphthalenedicarboxylic acid dianhydride, 1,4,5,8-naphthalenedicarboxylic acid dianhydride, 2,3, 6,7-Naphthalenedicarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride Anhydride etc.

(Other tetracarboxylic dianhydrides) As the tetracarboxylic dianhydride, in addition to the above, polysiloxane-based tetracarboxylic dianhydride or tetracarboxylic dianhydride containing a fluorine atom can also be used. As the tetracarboxylic dianhydride containing fluorine atoms, for example, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (alias ：4,4'-(hexafluoroisopropylidene)-diphthalic dianhydride), 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3, 3-hexafluoropropane dianhydride, 2,2'-bis(trifluoromethyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluorotrimethylene ) Diphthalic dianhydride, 4,4'-(octafluorotetramethylene) diphthalic dianhydride, 2,2'-bis(trifluoromethyl)-4,4',5, 5'-Biphenyltetracarboxylic dianhydride, 4,4'-(hexafluorotrimethylene)diphthalic dianhydride, 4,4'-(octafluorotetramethylene)diphthalic acid Anhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl) )-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoro Propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, etc.

The tetracarboxylic dianhydride that derives the tetracarboxylic acid residue contained in the polyimide of the present invention may be only one type, or may include two or more types. In order to improve high surface hardness and bending resistance, it is preferable to include tetracarboxylic acid residues derived from aliphatic tetracarboxylic dianhydrides and/or tetracarboxylic acid residues derived from tetracarboxylic dianhydrides containing fluorine atoms It is more preferable to include a tetracarboxylic acid residue derived from alicyclic tetracarboxylic dianhydride and/or a tetracarboxylic acid residue derived from a tetracarboxylic dianhydride containing a fluorine atom. In addition, by having the above structure, the solvent solubility of polyimide also tends to be improved.

The ratio of the tetracarboxylic acid residues derived from the aliphatic tetracarboxylic dianhydride to all the tetracarboxylic acid residues contained in the polyimide of the present invention is not particularly limited, and is preferably 10 mol% or more, more It is preferably 25 mol% or more, and more preferably 40 mol% or more. In addition, there is no upper limit to the ratio, and may be 100 mol%. When the ratio of the tetracarboxylic acid residues derived from the tetracarboxylic dianhydride is higher than the above lower limit, there is a tendency for high surface hardness and bending resistance to be improved, and solubility to solvents to be higher.

＜Units derived from diamine compounds＞ As the diamine compound that derives the diamine residue contained in the polyimide of the present invention, aromatic diamine compounds and aliphatic diamine compounds (aliphatic diamine compounds include alicyclic diamine compounds and Chain aliphatic diamine compound). These diamine compounds may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

(Aromatic diamine compound) Examples of aromatic diamine compounds include: diamine compounds with one aromatic ring in one molecule, diamine compounds with condensed aromatic rings in one molecule, and diamines with two or more independent aromatic rings in one molecule Compound.

As the diamine compound having one aromatic ring in one molecule, for example, 1,4-phenylenediamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 4-fluoro-1,2- Phenylenediamine, 4-fluoro-1,3-phenylenediamine, 3-trifluoromethyl-1,5-phenylenediamine, 4-trifluoromethyl-1,5-phenylenediamine, 4-trifluoro Methyl-1,2-phenylenediamine, 2-trifluoromethyl-1,4-phenylenediamine, etc.

Examples of diamine compounds having a condensed aromatic ring in one molecule include: 4,4'-(9-phenylene)diphenylamine, 2,7-diaminopyridine, 1,5-diaminonaphthalene, 3 ,7-Diamino-2,8-dimethyldibenzothiophene 5,5-dioxide, etc.

As a diamine compound having two or more independent aromatic rings in one molecule, as those having a biphenyl structure, 4,4'-(biphenyl-2,5-diyldioxy)bisaniline, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl (alias: 3,3'-dimethyl Benzidine), 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, 4,4'-diamine -3,3'-dimethoxybiphenyl, 4,4'-diamino-2,2'-dichlorobiphenyl, 4,4'-diamino-3,3'-dichlorobiphenyl Benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diamino-2-methyl-2'-trifluoromethylbiphenyl, etc. . In addition, examples of linking groups that connect aromatic rings to each other include 4,4-diaminobenzaniline, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl Base ether, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis(4-(4-aminophenoxy)phenyl ) Chrysene, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, bis(4-(3-aminophenoxy)phenyl) chrysene, 1,3-bis(4 -Aminophenoxy) neopentane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide , N-(4-aminophenoxy)-4-aminoaniline, bis(3-aminophenyl) benzene, noralkanediamine, bis(4-(4-aminophenoxy)benzene Group), bis(4-(3-aminophenoxy)phenyl), 4,4'-diaminodiphenyl, 3,3'-diaminodiphenyl, N- [4-(4-Aminophenoxy)phenyl]-4-aminobenzamide, 4,4-diaminobenzamide, bis(3-aminophenyl)sulfide, etc. In addition, examples of those having a fluorine atom include: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-{4-amino-2 -(Trifluoromethyl)phenoxy)phenyl)hexafluoropropane, 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2-bis(3-amino) -4-Hydroxyphenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis {4-(4-Aminophenoxy)-3,5-dibromophenyl}hexafluoropropane, etc.

Among them, in order to have high surface hardness and increase in bending resistance, and a tendency to increase the elastic modulus, a diamine compound having a biphenyl structure or a diamine compound having a linking group that connects aromatic rings to each other is more preferable It is a diamine compound with a biphenyl structure.

(Aliphatic diamine compound) As an aliphatic diamine compound, an alicyclic diamine compound, a chain aliphatic diamine compound, etc. are mentioned.

As the alicyclic diamine compound, for example, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,4-diamino ring Hexane, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), etc.

As the chain aliphatic diamine compound, for example, 1,2-ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1 ,6-hexamethylenediamine, 1,5-diaminopentane, 1,10-diaminodecane, 1,2-diamino-2-methylpropane, 2,3-dimethyl 2-methyl-2,3-butanediamine, 2-methyl-1,5-diaminopentane, etc.

Among them, there are high surface hardness and improved bending resistance, and in terms of the tendency to improve heat resistance, the alicyclic diamine compound is preferred, and 1,4-diaminocyclohexane is particularly preferred. Alkane or 1,3-bis(aminomethyl)cyclohexane.

＜Unit derived from diisocyanate compound＞ As the diisocyanate compound which derives the diamine residue contained in the polyimide of this invention, an aromatic diisocyanate compound and an aliphatic diisocyanate compound are mentioned. These diisocyanate compounds may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

As the aromatic diisocyanate compound, for example, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 2,2-bis(4-isocyanatophenyl)hexafluoro Propane, 4,4'-diisocyanato-3,3'-dimethyldiphenylmethane, 1,5-diisocyanatonaphthalene, 4,4'-diisocyanatomethylene bis Phenyl ester, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-bis(isocyanatomethyl)benzene, toluene diisocyanate, etc.

Examples of the aliphatic diisocyanate compound include 1,3-bis(isocyanatomethyl)cyclohexane, hexamethylene diisocyanate, isophorone diisocyanate, and the like.

The diamine compound and/or the diisocyanate compound that derives the diamine residue contained in the polyimide of the present invention may be only one type or two or more types. In order to have high surface hardness and increase in bending resistance, and the tendency to increase the elastic modulus at 30°C, it is preferable to include diamine residues derived from the following compounds: 4,4'-diamino-3, 3'-dimethylbiphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl (alias: 3,3'-dimethylbenzidine), 4,4'-diamine -3,3'-dimethoxybiphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, 4,4'-bis(4-aminophenoxy) Biphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diamino-2-methyl-2'-trifluoromethylbiphenyl Biphenyl-based diamine compounds; and/or bis (4-(4-aminophenoxy) phenyl) clump, bis(4-(3-aminophenoxy) phenyl) clump, 4,4 '-Diaminodiphenyl sulfide, 3,3'-Diaminodiphenyl sulfide, N-[4-(4-aminophenoxy)phenyl]-4-aminobenzamide, Diamine compounds such as 4,4-diaminobenzaniline and bis(3-aminophenyl)sulphur. Among them, it is more preferable to include a diamine residue derived from the above-mentioned biphenyl-based diamine compound.

<The structure represented by the general formula (1)> The polyimide of the present invention may have a structure represented by the following general formula (1). Since the polyimide of the present invention has this structure, there is a tendency to achieve both high surface hardness and bending resistance more effectively, and to further improve solubility.

[化1]

In the general formula (1), R represents at least one divalent optionally substituted group selected from the group consisting of aromatic ring groups, heterocyclic groups, alicyclic groups, and chain aliphatic groups. * Indicates a bonding key.

In the general formula (1), R represents at least one divalent optionally substituted group selected from the group consisting of aromatic ring groups, heterocyclic groups, alicyclic groups, and chain aliphatic groups. The aromatic ring and heterocyclic ring are not particularly limited, and may be a condensed ring. The alicyclic ring is also not particularly limited, but is preferably a 3-10 membered ring. The chain aliphatic group is also not particularly limited, but it is preferably a straight-chain group with 1 or more and 20 carbon atoms. Furthermore, in terms of easy molecular weight control and good manufacturing stability, at least one selected from the group consisting of aromatic ring groups and chain aliphatic groups is preferred. Among them, the aromatic ring group preferably includes a benzene ring, a naphthalene ring, a biphenyl ring, a diphenyl ether, a benzophenone, a phenyl sulfide, a biphenyl sulfide, a biphenyl sulfide group, and , Preferably having a single ring or two aromatic rings. On the other hand, as the chain aliphatic group, those having a carbon number of 1 or more and 10 or less are preferable. When R is such a group, there is a tendency that the effect of the present invention is easily obtained. These aromatic ring groups, heterocyclic groups, alicyclic groups, and chain aliphatic groups may have substituents. Examples of the substituent which may be possessed include an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyl group, and a carboxyl group.

These aromatic ring groups, heterocyclic groups, alicyclic groups, and chain aliphatic groups may be used alone or in combination.

Specific examples of the structure represented by the general formula (1) include the following compounds derived from the reaction of a dicarboxylic acid compound and a diamine compound, or the reaction of a tetracarboxylic dianhydride and a dihydrazine compound The structure.

The polyimide of the present invention may have only one structure represented by the general formula (1), or may have a plurality of types. The structure represented by the general formula (1) is preferably derived from the reaction of a dicarboxylic acid compound and a diamine compound and/or a reaction of a tetracarboxylic dianhydride and a dihydrazine compound. The structure represented by the general formula (1) preferably has at least a structure derived from the reaction of a tetracarboxylic dianhydride and a dihydrazine compound.

Examples of dicarboxylic acid compounds derived from the structure represented by the general formula (1) include aromatic dicarboxylic acids, heterocyclic dicarboxylic acids, alicyclic dicarboxylic acids, and chain aliphatic dicarboxylic acids. The dicarboxylic acid compound can also be used in the form of an acyl halide in which a carboxyl group is halogenated in order to improve reactivity, for example, an acyl chloride in which a carboxyl group is chlorinated. In the present invention, when a halide such as dicarboxylic acid chloride is used as the dicarboxylic acid compound, it is also a structure derived from the reaction of the dicarboxylic acid compound and the diamine compound.

The introduction amount of the structure represented by the general formula (1) in the polyimide is not particularly limited. The concentration of the amide bond relative to the amide ring of the main chain is preferably 1 mol% or more, more preferably 5 mol% or more, more preferably 8 mol% or more. The introduction amount of the structure represented by the general formula (1) in the polyimide is preferably 900 mol% or less, more preferably 700 mol% or less, further preferably 500 mol% or less, particularly preferably 400 mol% or less . The introduction amount of the structure represented by the general formula (1) in the polyimide is within this range, and it tends to have both solvent solubility and elastic modulus, which is preferable.

In the structure represented by the general formula (1), the ratio of the reactant derived from the dicarboxylic acid compound and the diamine compound to the reactant derived from the dihydrazine compound and the tetracarboxylic dianhydride is not particularly limited. The ratio of the reactants derived from the dihydrazine compound and the tetracarboxylic dianhydride is preferably 5 mol% or more, more preferably 10 mol% or more, in terms of the ratio relative to the structure represented by the general formula (1), It is preferably 25 mol% or more, and particularly preferably 50 mol% or more. There is no upper limit to the ratio of the reactants derived from the dihydrazine compound and the tetracarboxylic dianhydride, and it can be 100 mol%. Since the ratio of the reactants derived from the bishydrazine compound and the tetracarboxylic dianhydride is more than the above lower limit, it tends to have both solvent solubility and elastic modulus, which is preferable.

The ratio of tetracarboxylic acid residues, diamine residues, dicarboxylic acid residues and dihydrazine residues contained in the polyimide of the present invention can be analyzed by using NMR, solid-state NMR, IR, etc. The composition is found. In addition, this ratio can be obtained by gas chromatography (GC), ¹ H-NMR, ¹³ C-NMR, two-dimensional NMR, mass spectrometry, etc. after dissolving in an alkali.

＜＜Structure derived from the reaction of dicarboxylic acid compound and diamine compound＞＞ (Diamine compound) Examples of the diamine compound include aromatic diamine compounds and aliphatic diamine compounds (aliphatic diamine compounds include alicyclic diamine compounds and chain aliphatic diamine compounds). These diamine compounds may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

Examples of the diamine compound that reacts with the dicarboxylic acid compound include the compounds described above in the description of the diamine residue, and the preferable range is also the same.

(Dicarboxylic acid compound) Examples of the dicarboxylic acid compound include aromatic dicarboxylic acid compounds (including heteroaromatic dicarboxylic acid compounds), alicyclic dicarboxylic acid compounds, and chain aliphatic dicarboxylic acid compounds. These dicarboxylic acid compounds may be used individually by 1 type, and may be used for 2 or more types in arbitrary ratios and combinations.

Examples of the aromatic dicarboxylic acid compound include: monocyclic interphthalic acid, terephthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, etc.; Aromatic ring of 4,4'-carbonyldibenzoic acid, 2,2'-biphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane , 4-(carboxymethyl)benzoic acid, 4,4'-oxydibenzoic acid, 4,4'-sulfonyl dibenzoic acid, 1,2-bis(4-carboxyphenyl)ethane, 4, 4'-stilbene dicarboxylic acid, etc.; 1,4-naphthalenedicarboxylic acid and 2,3-naphthalenedicarboxylic acid with condensed ring; 2,2'-bicinchoninic acid, 2,2'- with heterocycle Bipyridine-3,3'-dicarboxylic acid, 2,2'-bipyridine-4,4'-dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, 2,2' -Bipyridine-6,6'-dicarboxylic acid, 2,5-furandicarboxylic acid, etc.

Examples of the alicyclic dicarboxylic acid compound include: bicyclo[2.2.2]octane-1,4-dicarboxylic acid, 1,3-adamantane dicarboxylic acid, and cis 4-cyclohexene-1,2 -Dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, decahydro-1,4-naphthalenedicarboxylic acid, etc.

As a chain aliphatic dicarboxylic acid compound, glutaric acid, adipic acid, azelaic acid, malonic acid, sebacic acid, succinic acid, etc. are mentioned.

As the dicarboxylic acid compound, in order to have a tendency to easily have both solvent solubility and elastic modulus, it is preferably a monocyclic aromatic dicarboxylic acid compound, a dicarboxylic acid compound having two or more independent aromatic rings, and a chain Like dicarboxylic acid compounds.

As mentioned above, the dicarboxylic acid compound can be used in the form of chlorine to increase the reactivity. In this case, the preferred compound is the same as the above.

＜＜The structure derived from the reaction of tetracarboxylic dianhydride and dihydrazine compound＞＞ (Tetracarboxylic dianhydride) Examples of tetracarboxylic dianhydrides include aromatic tetracarboxylic dianhydrides and aliphatic tetracarboxylic dianhydrides (aliphatic tetracarboxylic dianhydrides include alicyclic tetracarboxylic dianhydrides and chain aliphatic tetracarboxylic acids Dianhydride). These tetracarboxylic dianhydrides may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

Examples of the tetracarboxylic dianhydride compound that reacts with the bishydrazine compound include the compounds described above in the description of the tetracarboxylic acid residue, and the preferred range is also the same.

(Dihydrazine compound) The dihydrazine compound is not particularly limited, and examples thereof include aromatic dihydrazine compounds and aliphatic dihydrazine compounds (including alicyclic dihydrazine compounds and chain aliphatic dihydrazine compounds). These dihydrazine compounds may be used individually by 1 type, and may be used for 2 or more types in arbitrary ratios and combinations.

Examples of the aromatic dihydrazine compound include: monocyclic dihydrazine phthalate, dihydrazine terephthalate, dihydrazine phthalate, and 2,5-dimethylterephthalic acid Dihydrazine, etc.; 4,4'-carbonyldibenzoic acid dihydrazide, 2,2'-biphenyl dicarboxylic acid dihydrazide, 4,4'-biphenyl diphenyl dihydrazide with two or more independent aromatic rings Dihydrazide carboxylate, 2,2-bis(4-carboxyphenyl)hexafluoropropane dihydrazide, 4-(carboxymethyl)benzoic acid dihydrazide, 4,4'-oxydibenzoic acid dihydrazide , 4,4'-sulfonyl dibenzoic acid dihydrazine, 1,2-bis(4-carboxyphenyl)ethane dihydrazine, 4,4'-stilbene dicarboxylic acid dihydrazide, etc.; with condensation Ring 1,4-naphthalenedicarboxylic acid dihydrazine, 2,3-naphthalenedicarboxylic acid dihydrazine, etc.; 2,2'-dicinchoninic acid dihydrazide, 2,2'-bipyridine with heterocyclic ring -3,3'-Dicarboxylic acid dihydrazine, 2,2'-Bipyridine-4,4'-dicarboxylic acid dihydrazine, 2,2'-Bipyridine-5,5'-dicarboxylic acid Dihydrazine, 2,2'-bipyridine-6,6'-dicarboxylic acid dihydrazine, 2,5-furandicarboxylic acid dihydrazine, etc.

Examples of the alicyclic dihydrazine compound include: bicyclo[2.2.2]octane-1,4-dicarboxylic acid dihydrazide, 1,3-adamantane dicarboxylic acid dihydrazide, and cis 4-ring Hexene-1,2-dicarboxylic acid dihydrazine, 1,4-cyclohexanedicarboxylic acid dihydrazine, 1,3-cyclohexanedicarboxylic acid dihydrazine, decahydro-1,4-naphthalene Dicarboxylic acid dihydrazine and so on.

Examples of the chain aliphatic dihydrazine compound include: dihydrazine adipic acid, dihydrazine azelate, dihydrazine dodecanedioate, dihydrazine malonate, and dihydrazide sebacate Hydrazine, dihydrazine succinate, oxadiazine, etc.

As the dihydrazine compound, in order to have a tendency to increase the elastic modulus, a monocyclic aromatic dihydrazine compound and a dihydrazine compound having two or more independent aromatic rings are preferred.

<To meet E _'RT ⁰ and preferred design of G _N> to meet the polyimide film of the present invention E' _RT G _N ⁰ and the polyimide of the tetracarboxylic acid residue and a diamine residue The molecular design such as the preferred combination of the groups is not particularly limited, and it is preferable that the tetracarboxylic acid residue contains an alicyclic structure. From the viewpoint of having both high surface hardness and bending resistance, as well as the rigidity and flexibility of the molecular skeleton, it is preferable to use at least the above-mentioned aliphatic tetracarboxylic acid dianhydride as the raw material of polyimide As the anhydride, alicyclic tetracarboxylic dianhydride is more preferably used, and 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride or the like is particularly preferably used.

From the viewpoint of high surface hardness and bending resistance, the ratio of alicyclic tetracarboxylic acid residues among all the tetracarboxylic acid residues contained in the polyimide of the present invention is generally preferably 10 mol% or more , And more preferably 30 mol% or more, more preferably 50 mol% or more, and particularly preferably 80 mol% or more. The upper limit of this ratio does not particularly exist, and may be 100 mol%.

＜Molecular weight of polyimide＞ The molecular weight of the polyimide of the present invention is not particularly limited, but in terms of the number average molecular weight (Mn) in terms of polystyrene, it is preferably 500 or more, more preferably 1,000 or more, and still more preferably 1,500 or more. On the other hand, the molecular weight is preferably 80,000 or less, more preferably 60,000 or less, and still more preferably 40,000 or less. If the number average molecular weight (Mn) of the polyimide is in this range, the solubility, solution viscosity, etc. will be in the range that can be easily handled by ordinary equipment, so it is preferable. The polystyrene conversion number average molecular weight (Mn) of the polyimide of the present invention can be obtained by gel permeation chromatography (GPC).

The mass average molecular weight (Mw) of the polyimide of the present invention is preferably 1,000 or more, more preferably 2,000 or more, and still more preferably 5,000 or more. On the other hand, the mass average molecular weight (Mw) of the polyimide is preferably 300,000 or less, more preferably 200,000 or less, and still more preferably 100,000 or less. If the mass average molecular weight (Mw) of the polyimide is in this range, the solubility, solution viscosity, etc. will be in the range that can be easily handled by ordinary equipment, and therefore it is preferable. The mass average molecular weight (Mw) of the polyimide of the present invention can be measured by the same method as the number average molecular weight (Mn) described above.

The molecular weight distribution (PDI: Mw/Mn) of the polyimide of the present invention is usually 1 or more, preferably 1,1 or more, and more preferably 1.2 or more. On the other hand, Mw/Mn is usually 20 or less, preferably 15 or less, and more preferably 10 or less. When Mw/Mn is in this range, the obtained molded body tends to be excellent in uniformity and smoothness.

＜Glass transition temperature of polyimide＞ The glass transition temperature (Tg) of the polyimide of the present invention is not particularly limited, and is preferably 150°C or higher, more preferably 180°C or higher, still more preferably 200°C or higher, and even more preferably 250°C or higher, especially It is preferably 260°C or higher. On the other hand, the glass transition temperature (Tg) of polyimide is preferably 400°C or lower, more preferably 380°C or lower. When the glass transition temperature (Tg) of polyimide is in this range, the heat resistance of the obtained molded body is improved, and the molding temperature is suppressed or the residual solvent in the low-load process such as molding under air is reduced. tendency. The glass transition temperature (Tg) of polyimide is equivalent to the peak temperature of α relaxation of tanδ (Ttanδ).

＜Production method of polyimide＞ The production method of the polyimide of the present invention is not particularly limited, and it can be produced by a conventionally known method. For example, there are the following methods: from tetracarboxylic dianhydride and diamine compounds and/or diisocyanate compounds to produce polyimide precursors, to imidize them to obtain polyimides; from tetracarboxylic dianhydrides and diisocyanate compounds The amine compound and/or diisocyanate compound directly produces polyimide.

As a method of producing a polyimide containing the structure represented by the general formula (1), there are the following methods: from tetracarboxylic dianhydride and/or dicarboxylic acid compound, and diamine compound, diisocyanate compound and/or di A hydrazine compound is used to produce a polyimide precursor, which is then imidized to obtain a polyimide; from tetracarboxylic dianhydride and/or dicarboxylic acid compounds, and diamine compounds, diisocyanate compounds and/or di The hydrazine compound directly produces polyimine.

The dihydrazine compound can be reacted in the same manner as the diamine compound, and the dicarboxylic acid compound can be reacted in the same manner as the tetracarboxylic dianhydride. The dicarboxylic acid compound can also be used as a chain extender after producing a polyimide from a tetracarboxylic dianhydride, a diamine compound, a diisocyanate compound, and/or a dihydrazine compound.

Hereinafter, a method is described, which refers to "tetracarboxylic dianhydride and/or dicarboxylic acid compound" as "tetracarboxylic dianhydride, etc.", and refers to the "diamine compound, diisocyanate compound, and dihydrazine compound" "One or two or more types" are referred to as "diamine compounds etc.", and the polyimide of the present invention is produced by reacting tetracarboxylic dianhydride and the like with diamine compounds and the like.

＜＜Method of producing polyimide through polyimide precursor＞＞ (Structure of polyimide precursor) In the case of producing polyimine through a polyimide precursor, the polyimide precursor can be obtained by reacting, for example, tetracarboxylic dianhydride and the like with a diamine compound in a solvent. In this case, the order or method of addition of tetracarboxylic dianhydride and the like and diamine compound and the like are also not particularly limited. For example, a diamine compound, etc. and tetracarboxylic dianhydride, etc. are sequentially poured into a solvent, and stirred at an appropriate temperature, thereby obtaining a polyimide precursor.

The amount of tetracarboxylic dianhydride and the like is usually 0.7 mol or more, preferably 0.8 mol or more, and usually 1.3 mol or less, preferably 1.2 mol or less with respect to 1 mol of the diamine compound or the like. By setting the amount of tetracarboxylic dianhydride etc. in this range, the yield of the obtained polyimide precursor tends to increase.

The concentration of the tetracarboxylic dianhydride and the diamine compound in the reaction solution can be appropriately set according to the reaction conditions or the viscosity of the polyimide precursor obtained.

The total concentration of tetracarboxylic dianhydride, etc. and diamine compound, etc. is not particularly limited. With respect to the total amount of the reaction solution, it is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less. It is preferably 50% by mass or less. Since the concentration of the tetracarboxylic dianhydride and the diamine compound in the reaction solution is not too low, the molecular weight tends to expand. Since the concentration of the tetracarboxylic dianhydride and the diamine compound in the reaction liquid is not too high, the viscosity of the reaction liquid will not be too high and it tends to be easy to stir.

The temperature at which the tetracarboxylic dianhydride, etc. and the diamine compound are reacted in the solvent is not particularly limited as long as it is the temperature at which the reaction proceeds. It is usually 0°C or higher, preferably 20°C or higher, and usually 120°C or lower , Preferably below 100°C. The reaction time is usually 1 hour or more, preferably 2 hours or more, and usually 100 hours or less, preferably 42 hours or less. By carrying out under such conditions, there is a tendency to obtain the polyimide precursor at low cost and with better yield. The pressure during the reaction can be any of normal pressure, increased pressure and reduced pressure. The reaction atmosphere can be air or inert atmosphere.

The solvent used when reacting tetracarboxylic dianhydride etc. with a diamine compound etc. is not specifically limited. Examples of the reaction solvent include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene, mesitylene, and anisole; carbon tetrachloride, dichloromethane, chloroform, 1, Halogenated hydrocarbon solvents such as 2-dichloroethane, chlorobenzene, dichlorobenzene, and fluorobenzene; ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, and methoxybenzene; acetone, methyl ethyl Ketone solvents such as ketone, cyclohexanone, methyl isobutyl ketone; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether B Glycol solvents such as acid esters; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; Heterocyclic solvents such as pyridine, picoline, lutidine, quinoline and isoquinoline; phenolic solvents such as phenol and cresol; γ-butyrolactone, γ-valerolactone, Lactone-based solvents such as δ-valerolactone. These solvents may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

In the present invention, it is particularly preferred to use dimethylacetamide (DMAc) among these manufacturing solvents.

The obtained polyimide precursor can be directly used for subsequent imidization, or it can be used by being added to a poor solvent to precipitate as a solid.

The poor solvent used is not particularly limited, and can be appropriately selected according to the type of polyimide precursor. Examples of poor solvents include: ether solvents such as diethyl ether and diisopropyl ether; ketone solvents such as acetone, methyl ethyl ketone, isobutyl ketone, and methyl isobutyl ketone; methanol, ethanol, and isopropyl alcohol And other alcoholic solvents. Among them, in order to obtain the precipitates efficiently, the boiling point is low and the tendency to dry easily, an alcohol solvent is preferred. These solvents may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

(Imination of polyimide precursors) Polyimine can be obtained by dehydrating and cyclizing the polyimine precursor obtained by the above-mentioned method and the like in the presence of a solvent. The imidization can be carried out using any conventionally known method. Examples of the method of imidization include thermal cyclization and chemical cyclization. These imidization reactions can be carried out individually or in combination of plural kinds.

＜heating imidization＞ The solvent used when the polyimide precursor is heated and imidized can be the same as the solvent used in the above-mentioned reaction to obtain the polyimide precursor. The solvent used in the preparation of the polyimide precursor and the solvent used in the preparation of the polyimide may be the same or different. The water produced by the imidization will hinder the ring-closure reaction, so it can be discharged outside the system. The concentration of the polyimide precursor during the imidization reaction is not particularly limited, and is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40% by mass or less . By setting the concentration of the polyimide precursor within this range, the production efficiency is higher, and the solution viscosity can be produced easily.

The reaction temperature of the imidization is not particularly limited. It is usually 50°C or higher, preferably 80°C or higher, more preferably 100°C or higher, and usually 300°C or lower, preferably 280°C or lower, and more preferably Below 250°C. Since the reaction proceeds within this temperature range, the imidization reaction proceeds efficiently and the tendency of reactions other than the imidization reaction is suppressed, which is preferable. The pressure during the reaction can be any of normal pressure, increased pressure, and reduced pressure. The reaction atmosphere can be air or inert atmosphere.

As a promoter of imidization of imidization, a compound that can improve nucleophilicity and electrophilicity can also be added. Examples of the imidization accelerator include trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N,N-dimethylethanolamine, and N,N-diethyl Ethanolamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline, isoquinoline and other tertiary amines Compounds; Acetic acid, 4-hydroxyphenylacetic acid, 3-hydroxybenzoic acid, N-acetylglycine, N-benzylglycine and other carboxylic acid compounds; 3,5-dihydroxyacetophenone, 3, Polyphenol compounds such as methyl 5-dihydroxybenzoate, pyrogallol, methyl gallate, ethyl gallate, naphthalene-1,6-diol; 2-hydroxypyridine, 3-hydroxypyridine , 4-hydroxypyridine, 4-pyridine methanol, N,N-dimethylaminopyridine, nicotine aldehyde, isonicotinic aldehyde, picoline aldehyde, picoline aldoxime, nicotine aldoxime, isonicotine Aldoxime, ethyl picolinate, ethyl nicotinate, ethyl isonicotinate, nicotinic acid amide, isonicotinic acid amide, 2-hydroxynicotinic acid, 2,2'-bipyridine, 4 ,4'-Bipyridine, 3-methylpyridine, quinoline, isoquinoline, phenanthroline, 1,10-phenanthroline, imidazole, benzimidazole, 1,2,4-triazole and other heterocyclic compounds, etc. .

Among them, it is preferably at least one selected from the group consisting of tertiary amine compounds, carboxylic acid compounds, and heterocyclic compounds. Furthermore, in order to have a tendency to easily control the reaction rate, it is more preferably selected from triethyl At least one of the group consisting of base amine, imidazole and pyridine. These compounds may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

The amount of the imidization accelerator used relative to the carboxyl group of the polyimide precursor is usually 0.01 mol% or more, preferably 0.1 mol% or more, and more preferably 1 mol% or more. The amount of the imidization accelerator used relative to the carboxyl group of the polyimide precursor is preferably 50 mol% or less, and more preferably 10 mol% or less. Since the usage amount of the imidation accelerator is in the above range, there is a tendency for the imidation reaction to proceed efficiently. The time for adding the imidization accelerator can be adjusted appropriately, and it can be before heating or during heating. In addition, it may be added in plural times.

＜Chemical imidization＞ In the presence of a solvent, the polyimide precursor is chemically imidized using a dehydrating condensing agent to obtain polyimide.

As the solvent used in the chemical imidization, the same solvent as the solvent used in the above-mentioned reaction to obtain the polyimide precursor can be cited.

As the dehydrating condensing agent, for example, N,N-2 substituted carbodiimide such as N,N-dicyclohexylcarbodiimide and N,N-diphenylcarbodiimide; acetic anhydride, Acid anhydrides such as trifluoroacetic anhydride; chlorides such as sulfite chloride and toluene sulfonyl chloride; acetyl chloride, acetyl bromide, propyl iodide, acetyl fluoride, propyl chloride, propyl bromide, propyl iodide, propyl cyanide Fluorine, isobutyryl chloride, isobutyryl bromide, isobutyryl iodine, isobutyryl fluoride, n-butyryl chloride, n-butyryl bromide, n-butyryl iodine, n-butyryl fluoride, mono-, di-, tri- Chloroacetyl chloride, mono-, di-, tri-bromoacetyl chloride, mono-, di-, tri-iodoacetyl chloride, mono-, di-, tri-fluoroacetyl chloride, chloroacetic anhydride, phenyl Halogenated compounds such as phosphine dichloride, thiol chloride, thiol bromide, thiol iodine, and thiol fluoride; phosphorus compounds such as phosphorus trichloride, triphenyl phosphite, diethyl cyanophosphate, etc.

Among them, acid anhydrides and halogenated compounds are preferred, and especially in order to have a tendency to efficiently proceed the imidization reaction, acid anhydrides are more preferred. These compounds may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

The amount of the dehydrating condensing agent used is usually 0.1 mol or more, preferably 0.2 mol or more, and usually 1.6 mol or less, preferably 1.0 mol or less relative to 1 mol of the polyimide precursor. By setting the use amount of the dehydrating condensing agent in this range, the imidization can be efficiently performed.

The concentration of the polyimide precursor in the reaction solution during the imidization reaction is not particularly limited, and is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40% by mass or less. By setting the concentration of the polyimide precursor in the range, there is a tendency to increase the production efficiency and also to make the solution viscosity easy to manufacture.

The reaction temperature of the imidization is not particularly limited, and is usually 0°C or higher, preferably 10°C or higher, and more preferably 20°C or higher. In addition, it is usually 150°C or lower, preferably 130°C or lower, and more preferably 100°C or lower. Since the reaction proceeds within this temperature range, there is a tendency for the imidization reaction to proceed efficiently, which is preferable. Furthermore, it is preferable to suppress side reactions other than the imidization reaction. The pressure during the reaction may be any of normal pressure, increased pressure or reduced pressure. The reaction atmosphere can be air or inert atmosphere.

As a catalyst for accelerating imidization, an imidation accelerator such as the above-mentioned tertiary amine compound can also be added in the same manner as heating imidization.

＜＜Method for producing polyimide from tetracarboxylic dianhydride etc. and diamine compound etc.＞＞ Polyimide can be directly obtained from tetracarboxylic dianhydride, etc. and diamine compounds, etc., using conventionally known methods. The method is from the synthesis of the polyimide precursor to the imidization, without the termination of the reaction or the isolation of the precursor.

The order or method of addition of tetracarboxylic dianhydride, etc., and diamine compound, etc. are not particularly limited. For example, tetracarboxylic dianhydride, etc., and diamine compound, etc. are sequentially poured into a solvent, and the reaction proceeds until imidization Stir at the same temperature to obtain polyimide.

The amount of the diamine compound and the like is usually 0.7 mol or more, preferably 0.8 mol or more, and usually 1.3 mol or less, preferably 1.2 mol or less relative to 1 mol of tetracarboxylic dianhydride and the like. By setting the amount of the diamine compound etc. in this range, the yield of the obtained polyimide tends to increase.

The concentration of the tetracarboxylic dianhydride and the diamine compound in the reaction solution can be appropriately set according to the conditions or the viscosity during polymerization. The total concentration of the tetracarboxylic dianhydride etc. and the diamine compound etc. in the reaction liquid is not specifically set, but is usually 1% by mass or more, preferably 5% by mass or more, and usually 70% by mass or less, preferably 40 Less than mass%. Since the concentration in the reaction solution is in an appropriate range, the molecular weight tends to expand easily, and it also tends to be easily stirred.

The solvent used in this reaction may be the same as the solvent used in the above-mentioned reaction to obtain the polyimide precursor.

In the case of obtaining polyimide from tetracarboxylic dianhydride, etc. and diamine compounds, etc., as in the case of obtaining polyimide from the polyimide precursor, heating and/or imidization can be used. Or chemical imidization. In this case, the reaction conditions for the heating or chemical imidization are the same as the above.

The obtained polyimide can be used as it is, or it can be used as a polyimide composition by adding it to a poor solvent to precipitate the polyimide in a solid state, and then dissolving it in another solvent.

The poor solvent at this time is not particularly limited, and can be appropriately selected according to the type of polyimide. Examples of poor solvents include: ether solvents such as diethyl ether and diisopropyl ether; ketone solvents such as acetone, methyl ethyl ketone, isobutyl ketone, and methyl isobutyl ketone; methanol, ethanol, and isopropyl Alcohol-based solvents such as alcohol. Among them, in order to efficiently obtain precipitates, which have a low boiling point and tend to dry easily, alcoholic solvents such as isopropanol are preferred. These solvents may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

Examples of solvents for re-dissolving polyimine include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene, mesitylene, and anisole; N,N-dimethyl Amine-based solvents such as formamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; aprotic solvents such as dimethyl sulfide; ethylene glycol monomethyl ether, ethyl Glycol monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate and other glycol-based solvents; chloroform, dichloromethane, 1,2-dichloroethane and other halogen-based solvents Solvents, etc. These solvents may be used individually by 1 type, and may use 2 or more types in arbitrary ratios and combinations.

＜＜The case of using dicarboxylic acid chloride＞＞ When dicarboxylic acid chloride is used as the dicarboxylic acid compound to produce the polyimide of the present invention having the structure represented by the general formula (1), the reaction with the diamine compound or the like can be carried out by a conventionally known method . For example, dicarboxylic acid chloride or tetracarboxylic dianhydride containing dicarboxylic acid chloride can be added to a solution mixed with diamine compounds in the solvent, or dicarboxylic acid chloride or dicarboxylic acid dianhydride can be mixed in the solvent. Add diamine compound etc. to the solution of tetracarboxylic dianhydride.

The temperature when adding these compounds is not particularly limited, and is preferably -80°C or higher, more preferably -50°C or higher, still more preferably -30°C or higher, and preferably 100°C or lower, and more preferably 80°C Hereinafter, it is more preferably 50°C or lower. Since the temperature of addition is in this range, the reaction tends to be easy to control, so it is preferable.

The temperature at which the tetracarboxylic dianhydride containing dicarboxylic acid chloride is reacted with a diamine compound and the like is not particularly limited, but is preferably 0°C or higher, more preferably 5°C or higher, and still more preferably 10°C or higher, and more It is preferably 200°C or lower, more preferably 150°C or lower, and still more preferably 120°C or lower. Since the reaction temperature is in this range, it tends to be easy to control the reaction, so it is preferable.

When the tetracarboxylic dianhydride containing dicarboxylic acid chloride is reacted with a diamine compound, etc., a catalyst may be added. As long as the added catalyst is a known one, there is no particular limitation. As the catalyst, for example, trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, tri Tertiary amine compounds such as ethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline, and isoquinoline. These can be used individually by 1 type, and can also use 2 or more types in arbitrary ratios and combinations.

[Production method of polyimide film] The manufacturing method of the polyimide film of the present invention is not particularly limited. For example, a polyimide composition prepared by dissolving the polyimide film of the present invention in a solvent can be coated to form a film by using a casting method or the like Manufactured on the substrate.

The content of polyimine in the polyimide composition is not particularly limited, and can be appropriately adjusted according to the manufacturing process. The content of the polyimine in the polyimide composition is preferably 5% by mass or more, more preferably 10% by mass or more, more preferably 70% by mass or less, and more preferably 60% by mass or less. Since the content of polyimide is in this range, film formation and operation can be easily performed by normal equipment, which is preferable.

In addition to the polyimide and the solvent, the polyimide composition may also contain other components. Examples of other ingredients include: surfactants, antioxidants, lubricants, colorants, stabilizers, ultraviolet absorbers, antistatic agents, flame retardants, plasticizers, mold release agents, leveling agents, and defoamers剂 etc. In addition to this, inorganic fillers or organic fillers such as powdery, granular, plate-like, fibrous, etc. may be formulated as needed within a range that does not impair the purpose of the invention. These additional ingredients can be added at any stage of any step in the production of the polyimide precursor and/or polyimide composition.

Among these components, in order to increase the solubility of polyimine in solvents, it is preferable that the polyimine composition contains a surfactant. Examples of the surfactant include cationic surfactants, anionic surfactants, amphoteric surfactants, nonionic surfactants, and the like. The surfactant may be one type, or plural types may be used in combination.

Specific examples of the cationic surfactant used in the present invention include amine type, quaternary ammonium salt type, and the like. Examples of the amine type include aliphatic amines such as polyoxyethylene alkylamines and alkylamine salts, and heterocyclic amine salts such as alkylimidazolines. Examples of the quaternary ammonium salt type include: alkyl trimethyl ammonium salt or dialkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt, polydiallyl dimethyl ammonium salt; alkyl Chlorine salt type such as trimethyl ammonium chloride or dialkyl dimethyl ammonium chloride; non-chlorine type such as alkyl dimethyl ethyl ammonium ethyl sulfate.

Specific examples of the anionic surfactant used in the present invention include sulfate ester type, phosphate ester type, carboxylic acid type, and sulfonic acid type. Specific examples of the sulfate type include: alkyl sulfate, ethoxy sulfate, polyoxyethylene styrenated phenyl sulfate, polyoxyethylene alkyl ether sulfate, long-chain alcohol sulfate, and other sulfuric acid Esters, and their salts, etc. Specific examples of the phosphate ester type include polyoxyethylene alkyl ether phosphate ester, and these salts. Specific examples of the carboxylic acid type include: fatty acid, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether sulfosuccinic acid, alkenyl succinic acid, polyacrylic acid, styrene-maleic acid Acid copolymer ammonium, carboxymethyl cellulose, polyacrylic acid, polycarboxylic acid, and their salts, etc. As the sulfonic acid type, specifically, sulfonic acid, sulfosuccinic acid, alkylbenzene sulfonic acid, alkane sulfonic acid, α-olefin sulfonic acid, phenol sulfonic acid, sodium naphthalenesulfonate formalin condensate, And such salt, etc.

As the amphoteric surfactant used in the present invention, specific examples include betaine type, amine oxide type, N-alkylamino acid type, imidazoline type, and the like. Specific examples of the betaine type include amide betaines such as alkyl betaine and aliphatic amide betaine. As the amine oxide type, specifically, alkyl amine oxide and the like can be cited. Specific examples of the N-alkylamino acid type include N-alkyl-β-aminopropionate. Specific examples of the imidazoline type include 2-alkylimidazoline derivatives and the like.

Specific examples of the nonionic surfactant used in the present invention include ether type, ester type, ether/ester type, polyol type, amide type, polymer type, and the like. As the ether type, specific examples include: polyoxyalkylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, and polyoxyethylene alkyl amine Wait. Examples of ester types include sorbitan fatty acid esters, glycerin fatty acid esters, sucrose fatty acid esters, sucrose derivatives, fatty acid esters, and the like. Examples of the ether/ester type include polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene hydrogenated castor oil ether, and the like. Examples of the polyol type include alkyl glucoside and alkyl polyglucoside. Specific examples of the amide type include alkyl alkanol amides and the like. Specific examples of the polymer type include polyvinylpyrrolidone, polyalkylene polyamine alkylene oxide adduct, polyalkylene polyimine alkylene oxide adduct, and the like.

Specific examples of nonionic surfactants include polyoxyethylene alkyl ethers such as Emulgen 123P, Emulgen 130K, Emulgen 150, Emulgen 430, Emulgen 409PV, Emulgen 705, Emulgen 707, and Emulgen 709 (manufactured by Kao Corporation); Sorgen 40 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.), or sorbitan fatty acid esters such as Newcol 20, Newcol 60, and Newcol 80 (manufactured by Japan Emulsifier Company); sucrose benzoic acid such as Monopet SB (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) Esters; Sucrose fatty acid esters such as DK Ester F-110 (manufactured by Daiichi Industrial Pharmaceutical Co., Ltd.); polyvinylpyrrolidone such as Pitzcol K-30 and Pitzcol K-40 (manufactured by Daiichi Industrial Pharmaceutical Co., Ltd.).

Among the above-mentioned compounds, it is preferable to use a nonionic surfactant. By using non-ionic surfactants, the solubility of polyimine to solvents tends to be improved.

In order to have the tendency of improving the smoothness of the obtained polyimide film, it is preferable that the polyimide composition contains a leveling agent as another component. As a leveling agent, a polysiloxane compound etc. are mentioned, for example. The polysiloxane compound is not particularly limited, and examples thereof include: polyether modified silicone, polyether modified polydimethylsiloxane, polyether modified hydroxyl-containing polydimethylsiloxane, polyether Modified polymethylalkylsiloxane, polyester-modified polydimethylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyester-modified polymethylalkylsiloxane, Aralkyl modified polymethylalkylsiloxane, high polymer polysiloxane, amino modified polysiloxane, amino derivative polysiloxane, phenyl modified polysiloxane, polyether modified polysiloxane Oxygen etc. These can be used individually by 1 type, and can also use 2 or more types in arbitrary ratios and combinations.

The film forming method of the polyimide film using the above-mentioned polyimide composition is not particularly limited, and a method of coating the polyimide composition on a substrate and the like can be mentioned.

Examples of coating methods include die nozzle coating, spin coating, dip coating, screen printing, spraying, casting methods (single-sheet method and continuous method), methods using a coating machine, and blowing Coating method, dipping method, calendering method, etc. These methods can be appropriately selected according to the coating area and the shape of the coated surface. Among these, in order to have good uniformity of the coating film thickness and good surface smoothness, it is preferable to use a casting method or a method using a coater, and more preferably a casting method.

The method of volatilizing the solvent contained in the film formed by coating etc. is also not specifically limited. Generally, the solvent is volatilized by heating the film formed by coating or the like. The heating method is not particularly limited, and examples thereof include hot air heating, vacuum heating, infrared heating, microwave heating, and heating by contact using a hot plate, heating roller, and the like.

The heating temperature in the case of volatilizing the solvent can be a better temperature according to the type of solvent. The heating temperature relative to the boiling point of the solvent is usually above the boiling point, preferably the boiling point of the solvent + 50°C or more, more preferably the boiling point of the solvent + 100°C or more, and usually the boiling point of the solvent + 200°C or less, preferably the boiling point of the solvent +180°C or less, more preferably the boiling point of the solvent +150°C or less. When the heating temperature is in the above range, the solvent is sufficiently volatilized, which is preferable in this respect.

The polyimide film of the present invention is obtained, for example, by coating the polyimide composition containing the polyimide of the present invention and a casting solvent on the support as described above, and then heating to peel the film from the support.

The method of peeling the polyimide film from the support is not particularly limited. In terms of peeling without impairing the properties of the film, etc., a physical peeling method or a laser peeling method is preferred.

Examples of physical peeling methods include the following methods: separating the periphery of the laminate containing the polyimide film/support to obtain the polyimide film; attracting the periphery to obtain the polyimide film; fixing the periphery and supporting The substrate moves to obtain a polyimide film.

[Thickness of Polyimide Film] The thickness of the polyimide film of the present invention is usually 1 μm or more, preferably 2 μm or more, and usually 300 μm or less, preferably 200 μm or less. With a thickness of 1 μm or more, the polyimide film can obtain sufficient strength, and it is obtained as a self-supporting film, which tends to improve the operability. In addition, by setting the thickness to 300 μm or less, it tends to be easy to ensure the uniformity of the film.

[Mechanical properties of polyimide film] The required performance of the polyimide film of the present invention depends on the application, but preferably has the following mechanical properties.

The tensile strength of the polyimide film of the present invention is not particularly limited. In the measurement at 23°C and 50% humidity, it is usually 50 MPa or more, preferably 70 MPa or more, and more preferably 100 MPa or more. It is preferably 150 MPa or more, and usually 400 MPa or less, and preferably 300 MPa or less.

The tensile elastic modulus of the polyimide film of the present invention is not particularly limited. In the measurement at 23°C and 50% humidity, it is usually 1500 MPa or more, preferably 1800 MPa or more, and more preferably 2000 MPa Above, more preferably 3000 MPa or more, and usually 20 GPa or less, and preferably 10 GPa or less.

The tensile elongation of the polyimide film of the present invention is not particularly limited. In the measurement at 23°C and 50% humidity, it is usually 10% GL or more, preferably 20% GL or more, and more preferably 50 GL% Above, and usually 400% GL or less, preferably 300% GL or less.

The pencil hardness of the polyimide film of the present invention is not particularly limited, and is preferably 2B or higher, more preferably B or higher, further preferably F or higher, and particularly preferably H or higher. As a method for measuring the pencil hardness of the surface hardness, JIS K 5600-5-4 and the like can be cited.

Since the polyimide film has mechanical properties in this range, it becomes a polyimide film with more excellent durability, which is preferable.

[Layered body] The polyimide film of the present invention can also be used in the form of a laminate. For example, the polyimide film of the present invention may be provided with a hard coat layer having functions such as damage resistance, abrasion resistance, a layer having functions such as optical compensation, and an adhesive layer. The same or different layers can also be provided on both sides of the polyimide film of the present invention.

In terms of high surface hardness and excellent bending resistance, high light transmission and elastic modulus, high flexibility, transparency, high solvent solubility, and high device applicability, the polyimide of the present invention The film is particularly useful as a cover film for displays and the like. In this application, it can be used in the form of a laminate having a hard coat layer on the polyimide film of the present invention.

The hard coat layer can be formed on the polyimide film directly or via an adhesive layer or the like. The hard coat layer is not particularly limited, and it can be formed using a hard coat agent generally used. Examples of the hard coat agent include curable resins such as light and heat, inorganic materials, and curable resins containing inorganic materials. The forming method can be selected according to each material. In addition, in the hard coating agent, defoamers, leveling agents, tackifiers, anti-static agents, anti-fogging agents, etc. may be added as needed.

The thickness of the hard coat layer is not particularly limited, but is preferably 50 μm or more, and more preferably 60 μm or more. The thickness of the hard coat layer is preferably 200 μm or less, more preferably 180 μm or less. By setting the thickness of the hard coat layer within this range, there is a tendency for high surface hardness and excellent bending resistance.

The pencil hardness of the hard coat surface in the laminate of the present invention is not particularly limited, but is preferably B or higher, more preferably F or higher, further preferably H or higher, and particularly preferably 2H or higher.

In particular, when it is used for applications where light is transmitted through the laminate, such as display applications, the polyimide film/hard coat laminate is more preferably transparent. The YI (yellowness) of the laminate of the present invention is not particularly limited, but is preferably 5 or less, more preferably 4.5 or less, still more preferably 4 or less, and particularly preferably 3.5 or less.

The haze of the laminate of the present invention is not particularly limited, and is preferably 3% or less, more preferably 2% or less, still more preferably 1.5% or less, and particularly preferably less than 1%. [Example]

The following examples illustrate the present invention in further detail. The following examples are shown in order to explain the present invention in detail, and the present invention is not limited to the following examples as long as it does not violate its purpose.

[Film Forming] Using a 500 μm applicator, apply a solution of polyimide dissolved in N,N-dimethylacetamide to a concentration of 20% by mass on a soda glass substrate at 330°C or 280 Dry for 30 minutes at ℃. Thereafter, it was peeled off from the glass substrate to obtain a polyimide film having a thickness of 50 μm.

[The modulus of elasticity (E' _RT ) and the modulus of elasticity (G _N ⁰ ) of the rubber-like flat area at 30℃] Using a dynamic viscoelastic analysis device (SII6100 manufactured by Hitachi High-Tech Science), the width of the sample The measurement is carried out in the temperature range of room temperature to 480°C under the conditions of 10 mm, length 20 mm, frequency 10 Hz, and heating rate 5°C/min. The value at 30°C of the curve obtained by plotting the storage elastic modulus with respect to temperature is calculated as the elastic modulus (E' _RT ) at 30°C. In addition, the value of the elastic modulus (E') of the flat region of the temperature region exceeding Tg (E') is calculated as the elastic modulus (G _N ⁰ ) of the rubber-like flat region.

[Bending resistance] Using the MIT tester, a polyimide film with a width of 15 mm and a length of 110 mm was bent at a bending radius of 0.38 mm at a speed of 175 times/min, and the number of reciprocating bendings until the test piece broke was evaluated.

[Surface hardness] According to JIS K 5600-5-4, under a load condition of 750 g, the pencil hardness was measured by a pencil hardness tester (manufactured by Yasuda Seiki Co., Ltd.) to evaluate the surface hardness.

[Example 1] Add 16.7 g of 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride into a four-necked flask equipped with a nitrogen inlet pipe, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride 24.2 g, 4,4'-diamino-2,2'- 23.4 g of dimethylbiphenyl, 193 g of N-methyl-2-pyrrolidone (NMP), and 38.5 g of toluene were heated to reflux in an oil bath at 180°C for 20 hours. 100 g of the obtained reaction solution was diluted 7 times with N,N-dimethylacetamide (DMAc), and the solution was dropped into 3 L of isopropanol while stirring the solution at room temperature. The precipitated solid is separated and recovered by filtration to obtain a wet cake. Put the wet cake into a 500 mL separable flask, add 1 L of isopropanol, stir in an oil bath at 60°C, filter, separate and recover, and dry under reduced pressure at 150°C to obtain Polyimide 1. The obtained polyimide 1 was formed into a film at a drying temperature of 330°C. The obtained polyimide film was subjected to dynamic viscoelastic analysis, bending resistance and surface hardness evaluation. The results are shown in Table 1.

[Example 2] Mix 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride 16.7 g, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3- Hexafluoropropane dianhydride 24.2 g, 4,4'-diamino-2,2'-dimethylbiphenyl 23.4 g set to 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride 33.4 g, 35.2 g of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, except for 35.2 g, in the same manner as in Example 1, polyimide 2 was obtained. Using the obtained polyimide 2, it was formed into a film at a drying temperature of 330°C. The obtained polyimide film was subjected to dynamic viscoelastic analysis, bending resistance and surface hardness evaluation. The results are shown in Table 1.

[Example 3] Add 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride 30.9 g, 2,2' into a four-necked flask equipped with nitrogen introduction tube, cooler, Dean-Stark aggregator and stirrer -Bis(trifluoromethyl)-4,4'-diaminobiphenyl 24.0 g, dihydrazine isophthalate 4.9 g, NMP 140 g, xylene 92.7 g, heated and stirred in an oil bath at 80℃ After 1 hour, heat to reflux in an oil bath at 200°C for 13 hours. 20 g of the obtained reaction solution was diluted 5 times with DMAc, and the solution was dropped into 500 mL of isopropanol while stirring the solution at room temperature. After filtering and recovering the precipitated powder, put the wet cake into 200 mL of isopropanol and stir at room temperature for 30 minutes. After the powder was separated and recovered by filtration, it was dried under reduced pressure at 80°C for 30 minutes and at 150°C for 30 minutes to obtain polyimide 3. The obtained polyimide 3 was formed into a film at a drying temperature of 280°C. The obtained polyimide film was subjected to dynamic viscoelastic analysis, bending resistance and surface hardness evaluation. The results are shown in Table 1.

[Comparative Example 1] Mix 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride 16.7 g, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3- Hexafluoropropane dianhydride 24.2 g, 4,4'-diamino-2,2'-dimethylbiphenyl 23.4 g set to 2,2-bis(3,4-dicarboxyphenyl)-1,1 ,1,3,3,3-hexafluoropropane dianhydride 48.4 g, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl 35.2 g, other than that, follow the example 1 In the same manner, polyimide 4 was obtained. Using the obtained polyimide 4, it was formed into a film at a drying temperature of 330°C. Dynamic viscoelastic analysis and bending resistance evaluation of the obtained polyimide film were performed. The results are shown in Table 1.

[Comparative Example 2] Mix 3,3',4,4'-bicyclohexanetetracarboxylic dianhydride 16.7 g, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3- Except 24.2 g of hexafluoropropane dianhydride being 23.5 g of benzene-1,2,4,5-tetracarboxylic anhydride, it carried out similarly to Example 1, and obtained polyimide 5. Using the obtained polyimide 5, it was formed into a film at a drying temperature of 330°C. The obtained polyimide film was subjected to dynamic viscoelastic analysis, bending resistance and surface hardness evaluation. The results are shown in Table 1.

[Table 1] Modulus of Elasticity at 30℃ (E' _RT ) (Pa) Elastic modulus of rubber-like flat area (G _N ⁰ ) (Pa) Flexibility (times) Pencil hardness Example 1 4.8×10 ⁹ 1.8×10 ⁶ 3600 H Example 2 3.3×10 ⁹ 8.0×10 ⁶ 5100 2B Example 3 5.8×10 ⁹ 1.3×10 ⁷ 3360 H Comparative example 1 3.6×10 ⁹ 1.5×10 ⁷ 540 - Comparative example 2 1.4×10 ¹⁰ No clear G _N ⁰ 300 ＜3B

According to Table 1, it can be seen that the elastic modulus (E' _RT ) at 30°C is 3.0×10 ⁹ Pa or more and the elastic modulus (G _N ⁰ ) of the rubber-like flat area is less than 1.5×10 ⁷ Pa. The imine film can have both high surface hardness and bending resistance.

In contrast, the polyimide film of Comparative Example 1 has a modulus of elasticity (E' _RT ) of 3.0×10 ⁹ Pa or more at 30°C, and a modulus of elasticity (G _N ⁰ ) of the rubber-like flat area is 1.5× 10 ⁷ Pa, poor bending resistance. In Comparative Example 2, clear G _N ⁰ could not be observed, the bending resistance was poor, the pencil hardness was also low, and it was difficult to achieve both high surface hardness and bending resistance.

The present invention has been described in detail using a specific aspect, but the industry understands that various changes can be made without departing from the intent and scope of the present invention. This application is based on the Japanese patent application 2019-051100 filed on March 19, 2019 and the Japanese patent application 2019-153990 filed on August 26, 2019, the entirety of which is incorporated by reference.

FIG. 1 is a diagram illustrating the dynamic viscoelasticity measurement of the elastic modulus (G _N ⁰ ) of the rubber-like flat area of the present invention.

Claims (8)

A polyimide film whose elastic modulus (E' _RT ) at 30°C is 3.0×10 ⁹ Pa or more, and the elastic modulus (G _N ⁰ ) of the rubber-like flat area is less than 1.5×10 ⁷ Pa. The polyimide film of item 1 request, in which the elastic modulus (E _'RT) at 30 deg.] C of not less than 3.5 × 10 ⁹ Pa. The polyimide film of the requested item 1 or 2, in which the elastic modulus (E _'RT) at 30 deg.] C of not less than 4.0 × 10 ⁹ Pa. The polyimide film according to any one of claims 1 to 3, wherein the tetracarboxylic acid residue constituting the polyimine contained in the polyimide film includes an alicyclic structure. The polyimide film according to any one of claims 1 to 4, wherein the film thickness of the polyimide film is 1 μm or more and 300 μm or less. Such as the polyimide film of any one of claims 1 to 5, which is obtained by a casting method. A laminated body having a hard coat layer on the surface of the polyimide film according to any one of claims 1 to 6. The laminate of claim 7, wherein the film thickness of the hard coat layer is 50 μm or more and 200 μm or less.

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