CN115380058B

CN115380058B - Imide-amic acid copolymer, process for producing the same, varnish, and polyimide film

Info

Publication number: CN115380058B
Application number: CN202180027848.1A
Authority: CN
Inventors: 安孙子洋平; 大东葵; 石井健太郎; 三田寺淳
Original assignee: Mitsubishi Gas Chemical Co Inc
Current assignee: Mitsubishi Gas Chemical Co Inc
Priority date: 2020-04-16
Filing date: 2021-04-15
Publication date: 2024-07-09
Anticipated expiration: 2041-04-15
Also published as: KR20230007328A; JPWO2021210641A1; TW202142601A; CN115380058A; WO2021210641A1

Abstract

An imide-amic acid copolymer comprising: a repeating unit represented by the following formula (1) and composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2). (in the formula (1), X ¹ is a 4-valent aromatic group having 4 to 39 carbon atoms, X ² is a 4-valent aromatic group having 4 to 39 carbon atoms which is different from X ¹, Y ¹ is a group derived from diaminodiphenyl sulfone or the like, Y ² is a group derived from 4-aminophenyl-4-aminobenzoate or the like, s, t, and u are positive integers.)

Description

Imide-amic acid copolymer, process for producing the same, varnish, and polyimide film

Technical Field

The present invention relates to an imide-amic acid copolymer that is a precursor of a polyimide resin, a method for producing the same, a varnish containing the copolymer, and a polyimide film.

Background

Various applications of polyimide resins in the fields of electric/electronic parts and the like have been studied. For example, for the purpose of weight reduction and flexibility of a device, it is desired to replace a glass substrate used in an image display device such as a liquid crystal display or an OLED display with a plastic substrate, and research on a polyimide film suitable as the plastic substrate has been advanced. Polyimide films for this use require transparency and low yellowness.

In addition, when a polyimide film is formed by heating and curing a varnish applied to a glass support or a silicon wafer, residual stress is generated in the polyimide film. If the residual stress of the polyimide film is large, there is a problem that the glass support and the silicon wafer warp, and therefore, the polyimide film is also required to have a reduced residual stress.

In this regard, for example, patent document 1 discloses a polyimide precursor containing 2 specific amic acid structural units at a specific ratio in order to obtain a polyimide film having low residual stress, less warpage, low yellowness and high elongation.

Prior art literature

Patent literature

Patent document 1: international publication No. 2017/051827

Disclosure of Invention

Problems to be solved by the invention

As described above, the polyimide film for specific applications is required to have transparency and low yellowness. However, when the device type of the TFT is LTPS (low temperature polysilicon TFT), the process temperature exceeds 400 ℃, and polyimide as a substrate is required to have heat resistance to withstand a high temperature of 400 ℃ or higher, and transparency and low yellowness are required to be maintained even in such a thermal history.

In addition, as described above, the residual stress is also required to be reduced due to the problem of warpage of the support. Further, due to the difference in linear thermal expansion coefficient from the inorganic layer constituting the device, it is also necessary to reduce the linear thermal expansion coefficient for reasons of concern about peeling at the joint surface and deformation of the product.

Patent document 1 discloses a technique for reducing residual stress and yellowness, but it is insufficient, and in particular, a polyimide film excellent in heat resistance and the like while maintaining transparency and low yellowness cannot be obtained.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide: an imide-amic acid copolymer which is a precursor of a polyimide resin and is a polyimide film having a low residual stress and a low linear thermal expansion coefficient, excellent transparency and heat resistance, and a low yellowness, a method for producing the same, a varnish comprising the same, and a polyimide film are obtained.

Solution for solving the problem

The present inventors have found that a copolymer comprising a combination of specific structural units can solve the above-mentioned problems, and have completed the present invention.

That is, the present invention relates to [1] to [18] described below.

[1] An imide-amic acid copolymer comprising: a repeating unit represented by the following formula (1) and composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2).

(In the formula (1),

X ¹ is a C4-39 aromatic group and optionally has a group selected from the group consisting of-O-; at least 1 of the group consisting of-SO ₂-、-CO-、-CH₂-、-C(CH₃)₂-、-C₂H₄ O-and-S-as linking groups,

X ² is a C4-39 aromatic group different from X ¹ and optionally having a carbon number of 4 to 39 selected from the group consisting of-O-; at least 1 of the group consisting of-SO ₂-、-CO-、-CH₂-、-C(CH₃)₂-、-C₂H₄ O-and-S-as linking groups,

Y ¹ is a group represented by at least any 1 selected from the group consisting of the following formula (2), the following general formula (3) and the following general formula (4),

Y ² is a group represented by the following general formula (5),

S, t and u are positive integers. )

(In the formula (3), Z ¹ represents a single bond or a group represented by-O-,

In the formula (4), R independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms. )

(In the formula (5), Z ²、Z³ independently represents a group represented by-COO-or a group represented by-OCO-, R ¹、R²、R³ independently represents a 1-valent organic group having 1 to 20 carbon atoms, and h, i, j, k is an integer of 0 to 4.)

[2] The imide-amic acid copolymer of the above [1], wherein s is 1 to 50 and t is 1 to 50.

[3] The imide-amic acid copolymer of either [1] or [2], wherein u is 5 to 200.

[4] The imide-amic acid copolymer according to any one of the above [1] to [3], wherein X ¹ is a group represented by the following formula (6).

[5] The imide-amic acid copolymer according to any one of the above [1] to [4], wherein X ² is a group represented by the following formula (7).

[6] The imide-amic acid copolymer according to any one of the preceding [1] to [5], wherein the Imide Moiety (IM) has: structural units X1A derived from tetracarboxylic dianhydride and structural units Y1B derived from diamine,

The amic acid moiety (AM 1) has: structural units X2A derived from tetracarboxylic dianhydride, structural units Y1B derived from diamine,

The amic acid moiety (AM 2) has: structural units X2A derived from tetracarboxylic dianhydride, structural units Y2B derived from diamine,

The structural unit X1A includes: structural units derived from aromatic tetracarboxylic dianhydrides,

The structural unit X2A comprises: structural units derived from aromatic tetracarboxylic dianhydrides, which are different from the structural unit X1A,

The structural unit Y1B includes: a structural unit (B1) derived from a diamine (B1), the structural unit (B1) comprising at least any one selected from the group consisting of a structural unit (B11) derived from a compound represented by the following formula (B11), a structural unit (B12) derived from a compound represented by the following formula (B12), and a structural unit (B13) derived from a compound represented by the following formula (B13),

The structural unit Y2B includes: structural unit (B2) derived from a compound represented by the following general formula (B2).

(In the formula (b 12), Z ¹ represents a single bond or a group represented by-O-.

In the formula (b 13), R independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms.

In the formula (b 2), Z ²、Z³ each independently represents a group represented by-COO-or a group represented by-OCO-. R ¹、R²、R³ each independently represents a 1-valent organic group having 1 to 20 carbon atoms. h. i, j and k are integers of 0 to 4. )

[7] The imide-amic acid copolymer of the preceding [6], wherein the structural unit X2A comprises: structural units (A2) derived from aromatic tetracarboxylic dianhydrides (A2),

The structural unit (A2) includes at least 1 selected from the group consisting of a structural unit (a 21) derived from a compound represented by the following formula (a 21), a structural unit (a 22) derived from a compound represented by the following formula (a 22), a structural unit (a 23) derived from a compound represented by the following formula (a 23), a structural unit (a 24) derived from a compound represented by the following formula (a 24), and a structural unit (a 25) derived from a compound represented by the following formula (a 25).

[8] The imide-amic acid copolymer according to the above [6] or [7], further comprising a structural unit (B3) derived from a compound represented by the following general formula (B3).

( In the formula (b 3), Z ⁴ and Z ⁵ each independently represent a 2-valent aliphatic group or a 2-valent aromatic group, R ⁴ and R ⁵ each independently represent a 1-valent aromatic group or a 1-valent aliphatic group, R ⁶ and R ⁷ each independently represent a 1-valent aliphatic group, R ⁸ and R ⁹ each independently represent a 1-valent aliphatic group or a 1-valent aromatic group, m and n each independently represent an integer of 1 or more, and the sum of m and n represents an integer of 2 to 1000. Wherein at least one of R ⁴ and R ⁵ represents a 1-valent aromatic group. )

[9] The imide-amic acid copolymer of the preceding [8], wherein the aforementioned R ⁴ and R ⁵ are phenyl groups, and R ⁶ and R ⁷ are methyl groups.

[10] The imide-amic acid copolymer of the above [8] or [9], wherein the content of the polyorganosiloxane unit in the imide-amic acid copolymer is 1 to 20% by mass.

[11] The imide-amic acid copolymer according to any one of the preceding [6] to [10], wherein structural unit X1A comprises: structural unit (A1) derived from a compound represented by the following formula (A1).

[12] A varnish prepared by dissolving the copolymer according to any one of the above [1] to [11] in an organic solvent.

[13] A polyimide film comprising a polyimide resin obtained by imidizing the amic acid moiety in the copolymer of any one of [1] to [11 ].

[14] The polyimide film according to the above [13], wherein the polyimide resin has a weight average molecular weight (Mw) of 100000 ～ 300000.

[15] A process for producing an imide-amic acid copolymer, comprising the following steps 1 and 2.

Step 1: a step of reacting a tetracarboxylic acid component constituting an Imide Moiety (IM) with a diamine component to obtain an imide oligomer

Step 2: a step of reacting the imide oligomer obtained in the step 1 with a tetracarboxylic acid component and a diamine component constituting an amic acid moiety (AM 2) to obtain an imide-amic acid copolymer comprising a repeating unit composed of an Imide Moiety (IM) and amic acid moieties (AM 1) and (AM 2) represented by the following formula (1)

(In the formula (1),

Y ² is a group represented by the following general formula (5),

S, t and u are positive integers. )

(In the formula (3), Z ¹ represents a single bond or a group represented by-O-.

( In the formula (5), Z ²、Z³ each independently represents a group represented by-COO-or a group represented by-OCO-. R ¹、R²、R³ each independently represents a 1-valent organic group having 1 to 20 carbon atoms. h. i, j and k are integers of 0 to 4. )

[16] The method for producing an imide-amic acid copolymer according to the above [15], wherein the imide oligomer obtained in the step 1 has amino groups at both ends of the main chain of the molecular chain.

[17] The method for producing an imide-amic acid copolymer according to the above [15] or [16], wherein in step 1, the molar ratio of the diamine component to the tetracarboxylic acid component (diamine/tetracarboxylic acid) is 1.01 to 2.

[18] The method for producing an imide-amic acid copolymer according to any one of the preceding [15] to [17], wherein the copolymer is reacted with a diamine containing a polyorganosiloxane unit after the completion of the step 2.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there may be provided: an imide-amic acid copolymer which is a precursor of a polyimide resin and is a polyimide film having a low residual stress and a low linear thermal expansion coefficient, excellent transparency and heat resistance, and a low yellowness, a method for producing the same, a varnish comprising the same, and a polyimide film are obtained.

Detailed Description

[ Imide-amic acid copolymer ]

The imide-amic acid copolymer of the present invention comprises: a repeating unit represented by the following formula (1) and composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2).

(In the formula (1),

Y ² is a group represented by the following general formula (5),

S, t and u are positive integers. )

The reason why the imide-amic acid copolymer of the present invention is excellent as a raw material for a polyimide film, and the obtained polyimide film has excellent characteristics such as low residual stress and linear thermal expansion coefficient, excellent transparency, low yellowness, and high heat resistance, is not clear, but is considered as follows.

Consider that: the copolymer formed from the component derived from the tetracarboxylic acid containing an aromatic group and the specific diamine component has a large-volume skeleton of a trifluoromethyl, sulfo or Cardo structure, a rigid biphenyl skeleton, and an ester skeleton in an appropriate ratio, and therefore, can satisfy the requirements of low residual stress, low linear thermal expansion coefficient, low transparency, low yellowness, and high heat resistance required for TFT substrates and the like.

Another aspect is considered: even when the polyamide acid component containing a Cardo structure is in a proper ratio, thermal imidization is not easily caused at the time of film formation, and when a polymer having the polyamide acid component containing a Cardo structure is formed into a film, good physical properties are not easily exhibited in general, but in the imide-amic acid copolymer of the present invention, a part of the component containing a Cardo structure is imidized in advance at the time of polymerization of the polymer, and therefore, the physical properties after film formation are excellent.

< Imide Moiety (IM) >)

The Imide Moiety (IM) constituting the imide-amic acid copolymer of the present invention is a moiety represented by the aforementioned formula (1) (IM).

In the above-mentioned formula (1), X ¹ is a C4-39 aromatic group and optionally has a group selected from the group consisting of-O-; at least 1 of the group consisting of-SO ₂-、-CO-、-CH₂-、-C(CH₃)₂-、-C₂H₄ O-and-S-is used as linking group. The term "4-valent aromatic group" as used herein means that all of the 4 carbons bonded to the imide group are aromatic carbons. In the case where X ¹ contains 2 or more aromatic rings, the linking group is a linking group to which each aromatic ring is bonded. The linking group is not limited to these.

X ¹ is an aromatic group, and thus heat resistance of polyimide is improved.

X ¹ is preferably obtained by removing 2 dicarboxylic anhydride moieties (4 carboxyl moieties) from tetracarboxylic dianhydride which is a raw material for the structural unit X1A derived from tetracarboxylic dianhydride described later.

Among these, X ¹ is more preferably a group represented by the following formula (6).

In the formula (1), Y ¹ is a group represented by at least any one selected from the group consisting of the following formula (2), the following general formula (3) and the following general formula (4).

Y ¹ is preferably obtained by removing 2 amino moieties from diamine which is a raw material for the structural unit Y1B derived from diamine described later.

< Amic acid moiety (AM 2) >)

The amic acid moiety (AM 2) constituting the imide-amic acid copolymer of the present invention is a moiety represented by the aforementioned formula (1) (AM 2).

In the above-mentioned formula (1), X ² is a C4-39 aromatic group different from X ¹ and optionally having a carbon number of 4 to 39 selected from the group consisting of-O-; at least 1 of the group consisting of-SO ₂-、-CO-、-CH₂-、-C(CH₃)₂-、-C₂H₄ O-and-S-serves as a linking group. The term "4-valent aromatic group" as used herein means that all of the 4 carbons bonded to the imide group are aromatic carbons. In the case where X ¹ contains 2 or more aromatic rings, the linking group means a linking group to which each aromatic ring is bonded. The linking group is not limited to these.

X ² is preferably obtained by removing 2 dicarboxylic anhydride moieties (4 carboxyl moieties) from tetracarboxylic dianhydride which is a raw material for the structural unit X2A derived from tetracarboxylic dianhydride described later.

Among these, X ² is more preferably a group represented by the following formula (7).

In the formula (1), Y ² is a group represented by the following general formula (5).

Y ² is preferably obtained by removing 2 amino moieties from diamine which is a raw material for the structural unit Y2B derived from diamine described later.

< Amic acid moiety (AM 1) >)

The amic acid moiety (AM 1) constituting the imide-amic acid copolymer of the present invention is a moiety represented by the aforementioned formula (1) (AM 1).

The amic acid moiety (AM 1) is a binding moiety of the Imide Moiety (IM) and the amic acid moiety (AM 2), and X ² in the amic acid moiety (AM 1) is the same as the amic acid moiety (AM 2), and Y ¹ in the amic acid moiety (AM 1) is the same as the Imide Moiety (IM).

Composition of the imide-amic acid copolymer

In the formula (1), s is the number of repeating units of the Imide Moiety (IM) and is a positive integer.

From the viewpoints of transparency, low yellowness and high heat resistance, s is preferably 1 to 50, more preferably 1 to 15, still more preferably 1 to 10, still more preferably 1 to 5. The average number of repetitions of the Imide Moiety (IM), that is, the average value of s, is preferably 1 to 10, more preferably 1.5 to 9, still more preferably 1.5 to 8, still more preferably 1.7 to 5. The average number of repetitions of the Imide Moiety (IM) is an average value of the number of repetitions of the Imide Moiety (IM) of the entire imide-amic acid copolymer contained in the polyimide varnish or polyimide film described later, and the average value of s is an average value of s of the entire imide-amic acid copolymer contained in the polyimide varnish or polyimide film described later.

In the above formula (1), t is the number of repeating units of the amic acid moiety (AM 2) and is a positive integer.

From the viewpoints of high heat resistance, low residual stress, and low linear thermal expansion coefficient, t is preferably 1 to 50, more preferably 1 to 15, further preferably 1 to 10, still further preferably 1 to 5. The average repetition number of the amic acid moiety (AM 2), that is, the average value of t is preferably 1 to 10, more preferably 1.5 to 9, still more preferably 1.5 to 8, still more preferably 1.7 to 5. The average number of repetitions of the amic acid moiety (AM 2) is an average value of the number of repetitions of the amic acid moiety (AM 2) of the entire imide-amic acid copolymer contained in the polyimide varnish or polyimide film described later, and the average value of t is an average value of t of the entire imide-amic acid copolymer contained in the polyimide varnish or polyimide film described later.

In the formula (1), u is the number of repeating units composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2), and is a positive integer.

From the viewpoints of heat resistance, low residual stress, and low linear thermal expansion coefficient, u is preferably 5 to 200, more preferably 6 to 150, and further preferably 10 to 120.

The average number of repeating units of the Imide Moiety (IM), the amic acid moiety (AM 1) and the amic acid moiety (AM 2), that is, the average value of u, is preferably 5 to 200. The average number of repeating units of the Imide Moiety (IM), the amic acid moiety (AM 1) and the amic acid moiety (AM 2) is an average value of the number of repeating units of the Imide Moiety (IM), the amic acid moiety (AM 1) and the amic acid moiety (AM 2) of the entire imide-amic acid copolymer contained in the polyimide varnish or the polyimide film described later, and the average value of u is an average value of u of the entire imide-amic acid copolymer contained in the polyimide varnish or the polyimide film described later.

The ratio of the total of the Imide Moiety (IM), the amic acid moiety (AM 1) and the amic acid moiety (AM 2) to the imide-amic acid copolymer is preferably 80 mass% or more, more preferably 82 mass% or more, still more preferably 85 mass% or more, and the upper limit is not limited and is 100 mass% or less.

In contrast to the random presence of the imide moiety and the amic acid moiety of the existing imide-amic acid copolymers, it is believed that: the imide-amic acid copolymer of the present invention has a specific structure through the imide part (IM), the amic acid part (AM 1) and the amic acid part (AM 2), so that the residual stress, the linear thermal expansion coefficient, the transparency, the low yellowness, the heat resistance can be excellent.

< Structural units of imide-amic acid copolymer >)

The imide-amic acid copolymer of the present invention contains a repeating unit represented by the above formula (1) and composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2), and the structural units constituting the copolymer will be described below.

The imide-amic acid copolymer of the present invention preferably has the Imide Moiety (IM) described above: structural units X1A derived from tetracarboxylic dianhydride and structural units Y1B derived from diamine,

In the formula (b 2), Z ²、Z³ each independently represents a group represented by-COO-or a group represented by-OCO-. R ¹、R²、R³ each independently represents a 1-valent organic group having 1 to 20 carbon atoms. h. i, k and n are integers of 0 to 4. )

(Structural unit X1A)

The structural unit X1A is a structural unit derived from a tetracarboxylic dianhydride and contained in the imide part (IM) of the copolymer of the present invention.

The structural unit X1A is not limited as long as it contains a structural unit derived from an aromatic tetracarboxylic dianhydride, and the structural unit X1A preferably contains a structural unit (A1) derived from a compound represented by the following formula (A1).

The compound represented by the formula (a 1) is 9,9' -bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF).

The inclusion of the structural unit (A1) derived from the compound represented by the formula (A1) is preferable because it is transparent, low in yellowness and high in heat resistance.

When the structural unit X1A includes the structural unit (A1), the content ratio of the structural unit (A1) in the structural unit X1A is preferably 50 mol% or more, more preferably 55 mol% or more, further preferably 60 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more, further preferably 95 mol% or more. The upper limit of the content ratio of the structural unit (A1) is not particularly limited, but is 100 mol% or less. The structural unit a may be constituted only by the structural unit (A1).

The structural unit X1A may contain structural units other than the structural unit (A1). The tetracarboxylic dianhydride providing such a structural unit is not particularly limited, and examples thereof include alicyclic tetracarboxylic dianhydrides such as 1,2,4, 5-cyclohexane tetracarboxylic dianhydride, norbornane-2-spiro- α -cyclopentanone- α '-spiro-2' -norbornane-5, 5 ', 6' -tetracarboxylic dianhydride, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, 1,2,4, 5-cyclopentane tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, dicyclohexyl tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydrides such as 1,2,3, 4-butane tetracarboxylic dianhydride.

In the present specification, alicyclic tetracarboxylic dianhydride means tetracarboxylic dianhydride in which at least 2 α carbons of 1 anhydride (2 adjacent carboxyl groups) out of 4 α carbons of 2 anhydrides (4 carboxyl groups) are carbon atoms constituting an alicyclic ring, aromatic tetracarboxylic dianhydride means tetracarboxylic dianhydride in which 4 α carbons of 2 anhydrides (4 carboxyl groups) are carbon atoms constituting an aromatic ring, and aliphatic tetracarboxylic dianhydride means tetracarboxylic dianhydride which is neither alicyclic tetracarboxylic dianhydride nor aromatic tetracarboxylic dianhydride.

The number of structural units arbitrarily contained in the structural unit X1A may be 1 or 2 or more.

(Structural unit X2A)

The structural unit X2A is a structural unit derived from tetracarboxylic dianhydride which is occupied in the amic acid moiety (AM 2) and the amic acid moiety (AM 1) of the copolymer of the present invention, and contains a structural unit derived from aromatic tetracarboxylic dianhydride which is different from the structural unit X1A.

The structural unit X2A is not limited as long as it contains a structural unit derived from an aromatic tetracarboxylic dianhydride different from the structural unit X1A, and the structural unit X2A preferably contains a structural unit (A2) derived from an aromatic tetracarboxylic dianhydride (A2).

Here, the structural unit (A2) includes at least 1 selected from the group consisting of a structural unit (a 21) derived from a compound represented by the following formula (a 21), a structural unit (a 22) derived from a compound represented by the following formula (a 22), a structural unit (a 23) derived from a compound represented by the following formula (a 23), a structural unit (a 24) derived from a compound represented by the following formula (a 24), and a structural unit (a 25) derived from a compound represented by the following formula (a 25).

The compound represented by the formula (a 21) is diphenyl tetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3',4' -diphenyl tetracarboxylic dianhydride (s-BPDA) represented by the following formula (a 21 s), 2, 3',4' -diphenyl tetracarboxylic dianhydride (a-BPDA) represented by the following formula (a 21 a), and 2,2', 3' -diphenyl tetracarboxylic dianhydride (i-BPDA) represented by the following formula (a 21 i). Among them, 3',4' -biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a 21 s) is preferable.

The compound represented by the formula (a 22) is p-phenylene bis (trimellitate) dianhydride (TAHQ).

The compound represented by the formula (a 23) is oxydiphthalic anhydride (ODPA), and specific examples thereof include 4,4' -oxydiphthalic anhydride (s-ODPA) represented by the following formula (a 23 s), 3,4' -oxydiphthalic anhydride (a-ODPA) represented by the following formula (a 23 a), and 3,3' -oxydiphthalic anhydride (i-ODPA) represented by the following formula (a 23 i). Among them, 4' -oxydiphthalic anhydride (s-ODPA) represented by the following formula (a 23 s) is preferable.

The compound represented by the formula (a 24) is pyromellitic dianhydride (PMDA).

The compound represented by the formula (a 25) is 2,3,6, 7-naphthalene tetracarboxylic dianhydride.

From the viewpoints of high heat resistance and low residual stress, the structural unit (A2) preferably contains at least 1 selected from the group consisting of the structural unit (a 21) and the structural unit (a 22), more preferably contains the structural unit (a 21).

In particular, the structural unit (a 21) is preferable from the viewpoint of improving the heat resistance and thermal stability of the film and further reducing the residual stress, and the structural unit (a 22) is preferable from the viewpoint of reducing the residual stress and also reducing the linear thermal expansion coefficient.

The structural unit X2A may contain structural units other than the structural unit (A2). The tetracarboxylic dianhydride providing such a structural unit is not particularly limited, and examples thereof include alicyclic tetracarboxylic dianhydrides such as 1,2,4, 5-cyclohexane tetracarboxylic dianhydride, norbornane-2-spiro- α -cyclopentanone- α '-spiro-2' -norbornane-5, 5 ', 6' -tetracarboxylic dianhydride, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, 1,2,4, 5-cyclopentane tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, dicyclohexyl tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydrides such as 1,2,3, 4-butane tetracarboxylic dianhydride.

The number of structural units arbitrarily contained in the structural unit X2A may be 1 or 2 or more.

The total ratio of the structural units (a 21) to (a 25) in the structural unit (A2) is preferably 45 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol% or less. The structural unit (A2) may be composed of only 1 selected from the structural units (a 21) to (a 25), as long as it contains at least 1 selected from the structural units (a 21) to (a 25).

In the case where the structural unit (A2) contains 2 or more structural units selected from the structural units (a 21) to (a 25), the ratio of each structural unit in the structural unit (A2) is not particularly limited, and may be any ratio.

The ratio of the structural unit (A2) in the structural unit X2A is preferably 45 mol% or more, more preferably 60 mol% or more, and still more preferably 85 mol% or more. The upper limit of the content ratio is not particularly limited, but is 100 mol% or less.

When the structural unit X1A comprises the structural unit (A1) and the structural unit X2A comprises the structural unit (A2), the molar ratio of the structural unit (A1) to the structural unit (A2) [ A1)/(A2) ] among the structural units derived from the tetracarboxylic dianhydride of the imide-amic acid copolymer is preferably 10/90 to 55/45, more preferably 15/85 to 50/50, still more preferably 20/80 to 45/55.

(Structural unit Y1B)

The structural unit Y1B is a structural unit derived from diamine which is occupied in the imide part (IM) and the amic acid part (AM 1) of the copolymer of the present invention, and includes a structural unit (B1) derived from diamine (B1), and the structural unit (B1) includes at least any one selected from the group consisting of a structural unit (B11) derived from a compound represented by the following formula (B11), a structural unit (B12) derived from a compound represented by the following formula (B12), and a structural unit (B13) derived from a compound represented by the following formula (B13).

From the viewpoint of heat resistance, it is preferable that the structural unit (B13) contains a structural unit derived from a compound represented by formula (B13) having a Cardo structure, and from the viewpoint of transparency, it is preferable that the structural unit (B11) contains a structural unit derived from a compound represented by formula (B11) having an electron withdrawing group, and the structural unit (B12) contains a structural unit derived from a compound represented by formula (B12).

The total ratio of the structural units (B11) to (B13) in the structural unit (B1) is preferably 45 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol% or less.

In the formula (b 13), R independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms. )

The structural unit (B11) is preferably: at least 1 selected from the group consisting of a structural unit (B111) derived from a compound represented by the following formula (B111) and a structural unit (B112) derived from a compound represented by the following formula (B112).

The structural unit (B11) may be only the structural unit (B111), may be only the structural unit (B112), or may be a combination of the structural unit (B111) and the structural unit (B112).

The compound represented by the formula (b 111) is 4,4 '-diaminodiphenyl sulfone (4, 4' -DDS), and the compound represented by the formula (b 112) is 3,3 '-diaminodiphenyl sulfone (3, 3' -DDS).

The structural unit (B12) preferably contains at least 1 structural unit selected from the group consisting of a structural unit (B121) derived from a compound represented by the following formula (B121) and a structural unit (B122) derived from a compound represented by the following formula (B122), more preferably contains a structural unit (B122) derived from a compound represented by the following formula (B122).

The compound represented by the formula (b 121) is 2,2 '-bis (trifluoromethyl) -4,4' -diaminodiphenyl ether (6 FODA).

The compound represented by the formula (b 122) is 2,2' -bis (trifluoromethyl) benzidine (TFMB).

The structural unit (B13) is a structural unit derived from the compound represented by the formula (B13).

In the formula (b 13), R is each independently a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms, preferably each independently a hydrogen atom, a fluorine atom or a methyl group, and more preferably a hydrogen atom.

Examples of the compound represented by the formula (b 13) include 9, 9-bis (4-aminophenyl) fluorene (BAFL), 9-bis (3-fluoro-4-aminophenyl) fluorene, and 9, 9-bis (3-methyl-4-aminophenyl) fluorene, and preferably at least 1 selected from the group consisting of these 3 compounds, and more preferably 9, 9-bis (4-aminophenyl) fluorene from the viewpoint of heat resistance.

The structural unit Y1B may contain structural units other than the structural unit (B1). The diamine providing such a structural unit is not particularly limited, and examples thereof include 1, 4-phenylenediamine, p-xylylenediamine, 3, 5-diaminobenzoic acid, 1, 5-diaminonaphthalene, 2 '-dimethylbiphenyl-4, 4' -diamine, 4 '-diaminodiphenylmethane, 1, 4-bis [2- (4-aminophenyl) -2-propyl ] benzene, 2-bis (4-aminophenyl) hexafluoropropane, 4' -diaminobenzanilide, 1- (4-aminophenyl) -2, 3-dihydro-1, 3-trimethyl-1H-indene-5-amine, and alpha, aromatic diamines such as α '-bis (4-aminophenyl) -1, 4-diisopropylbenzene, N' -bis (4-aminophenyl) terephthalamide, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, and 1, 4-bis (4-aminophenoxy) benzene; alicyclic diamines such as 1, 3-bis (aminomethyl) cyclohexane and 1, 4-bis (aminomethyl) cyclohexane; aliphatic diamines such as ethylenediamine and hexamethylenediamine.

In the present specification, an aromatic diamine means a diamine containing 1 or more aromatic rings, an alicyclic diamine means a diamine containing 1 or more alicyclic rings and containing no aromatic rings, and an aliphatic diamine means a diamine containing neither aromatic rings nor alicyclic rings.

The number of structural units optionally included in the structural unit Y1B may be 1 or 2 or more.

(Structural unit Y2B)

The structural unit Y2B is a structural unit derived from diamine, which is contained in the amic acid moiety (AM 2) of the copolymer of the present invention, and the structural unit Y2B includes a structural unit (B2) derived from a compound represented by the following general formula (B2) from the viewpoints of low residual stress, low linear thermal expansion coefficient, and heat resistance.

( In the formula (b 2), Z ²、Z³ each independently represents a group represented by-COO-or a group represented by-OCO-. R ¹、R²、R³ each independently represents a 1-valent organic group having 1 to 20 carbon atoms. h. i, j and k are integers of 0 to 4. )

From the viewpoints of heat resistance, low residual stress, and low linear thermal expansion coefficient, the structural unit (B2) preferably includes a structural unit (B21) derived from a compound represented by the following formula (B21).

The compound represented by the formula (b 21) is 4-aminophenyl-4-aminobenzoate (4-BAAB).

The structural unit Y2B may contain structural units other than the structural unit (B2). The diamine providing such a structural unit is not particularly limited, examples thereof include 1, 4-phenylenediamine, p-xylylenediamine, 3, 5-diaminobenzoic acid, 1, 5-diaminonaphthalene, 2 '-dimethylbiphenyl-4, 4' -diamine, 2 '-dimethylbiphenyl-4, 4' -diamine, 4 '-diaminodiphenylmethane, and 1, 4-bis [2- (4-aminophenyl) -2-propyl ] benzene, 2-bis (4-aminophenyl) hexafluoropropane, 4' -diaminoanilide, 1- (4-aminophenyl) -2, 3-dihydro-1, 3-trimethyl-1H-inden-5-amine, alpha, aromatic diamines such as α '-bis (4-aminophenyl) -1, 4-diisopropylbenzene, N' -bis (4-aminophenyl) terephthalamide, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, and 1, 4-bis (4-aminophenoxy) benzene; alicyclic diamines such as 1, 3-bis (aminomethyl) cyclohexane and 1, 4-bis (aminomethyl) cyclohexane; aliphatic diamines such as ethylenediamine and hexamethylenediamine.

The number of structural units included in any of the structural units Y2B may be 1 or 2 or more.

The ratio of the structural unit (B1) in the diamine-derived structural unit of the copolymer is preferably 10 to 55 mol%, more preferably 20 to 50 mol%, and even more preferably 25 to 45 mol%, based on 100 mol% of the total of the structural units Y1B and Y2B.

The ratio of the structural unit (B2) in the diamine-derived structural unit of the copolymer, when the total of the structural units Y1B and Y2B is 100 mol%, is preferably 45 to 90 mol%, more preferably 50 to 80 mol%, and still more preferably 55 to 75 mol%.

When the structural unit Y1B comprises the structural unit (B1) and the structural unit Y2B comprises the structural unit (B2), the molar ratio of the structural unit (B1) to the structural unit (B2) [ (B1)/(B2) ] among the structural units derived from diamine of the imide-amic acid copolymer is preferably 10/90 to 55/45, more preferably 20/80 to 50/50, still more preferably 25/75 to 45/55.

The ratio of the total of the structural units (B1) and the structural units (B2) in the diamine-derived structural units of the copolymer, when the total of the structural units Y1B and the structural units Y2B is 100 mol%, is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and the upper limit is not particularly limited and is 100 mol% or less.

The ratio of the total of the structural units X1A, X2A, Y1B and Y2B to the total of the structural units constituting the imide-amic acid copolymer is preferably 80 mass% or more, more preferably 82 mass% or more, still more preferably 85 mass% or more, and the upper limit is not limited and is 100 mass% or less.

(Other structural units)

The imide-amic acid copolymer of the present invention may contain structural units other than the aforementioned structural unit X1A, structural unit X2A, structural unit Y1B and structural unit Y2B.

The imide-amic acid copolymer of the present invention may further comprise a structural unit (B3) derived from a compound represented by the following general formula (B3). By including the structural unit (B3), the residual stress is reduced.

In the formula (b 3), Z ⁴ and Z ⁵ each independently represent a 2-valent aliphatic group or a 2-valent aromatic group, R ⁴ and R ⁵ each independently represent a 1-valent aromatic group or a 1-valent aliphatic group, R ⁶ and R ⁷ each independently represent a 1-valent aliphatic group, R ⁸ and R ⁹ each independently represent a 1-valent aliphatic group or a 1-valent aromatic group, m and n each independently represent an integer of 1 or more, and the sum of m and n represents an integer of 2 to 1000. Wherein at least one of R ⁴ and R ⁵ represents a 1-valent aromatic group.

In the formula (b 3), at least 2 different repeating units described in parallel by [ ] may be repeated in random, alternating or block form and in sequence, respectively.

In the formula (b 3), the aliphatic group having a valence of 2 or the aromatic group having a valence of 2 in Z ⁴ and Z ⁵ may be substituted with a fluorine atom, and may contain an oxygen atom. When an oxygen atom is contained as an ether bond, the carbon number indicated below refers to the total carbon number contained in an aliphatic group or an aromatic group.

Examples of the aliphatic group having 2 valences include a saturated or unsaturated aliphatic group having 2 valences of 1 to 20 carbon atoms. The carbon number of the aliphatic group having a valence of 2 is preferably 3 to 20.

Examples of the saturated aliphatic group having 2 valences include an alkylene group and an alkyleneoxy group having 1 to 20 carbon atoms, and examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, and a dodecamethylene group, and examples of the alkyleneoxy group include a propyleneoxy group and a trimethylene oxy group.

Examples of the 2-valent unsaturated aliphatic group include an alkenylene group having 2 to 20 carbon atoms, for example, an alkenylene group, a propenylene group, and an alkylene group having an unsaturated double bond at the terminal.

Examples of the 2-valent aromatic group include an arylene group having 6 to 20 carbon atoms, an aralkylene group having 7 to 20 carbon atoms, and the like. Specific examples of the arylene group having 6 to 20 carbon atoms in Z ⁴ and Z ⁵ include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 4,4' -biphenylene group, a 2, 6-naphthylene group and the like.

As Z ⁴ and Z ⁵, trimethylene and p-phenylene are particularly preferable, and trimethylene is more preferable.

In the formula (b 3), as the aliphatic group having 1 valence in R ⁴～R⁹, there may be mentioned a saturated or unsaturated aliphatic group having 1 valence. Examples of the 1-valent saturated aliphatic group include an alkyl group having 1 to 22 carbon atoms, such as a methyl group, an ethyl group, and a propyl group. Examples of the 1-valent unsaturated aliphatic group include alkenyl groups having 2 to 22 carbon atoms, such as vinyl groups and propenyl groups. These groups may be substituted with fluorine atoms.

Examples of the 1-valent aromatic group in R ⁴、R⁵、R⁸ and R ⁹ in the formula (b 3) include an aryl group having 6 to 20 carbon atoms, an aryl group having 7 to 30 carbon atoms substituted with an alkyl group, an aralkyl group having 7 to 30 carbon atoms, and the like. As the aromatic group having a valence of 1, an aryl group is preferable, and a phenyl group is more preferable.

At least one of R ⁴ and R ⁵ represents an aromatic group having a valence of 1, preferably an aromatic group having a valence of 1 in each of Z ⁴ and Z ⁵, and more preferably R ⁴ and R ⁵ are each phenyl.

R ⁶ and R ⁷ are preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group.

As R ⁸ and R ⁹, a 1-valent aliphatic group is preferable, and a methyl group is more preferable.

As described above, among the compounds represented by the general formula (b 3), the compounds represented by the following formula (b 31) are preferable.

(In the formula (b 31), m and n have the same meanings as those of m and n in the formula (b 3)), and the preferable ranges are the same as those of m and n

M in the formulae (b 3) and (b 31) represents the number of repetitions of a siloxane unit to which at least 1 aromatic group of 1 is bonded, and n in the formulae (b 3) and (b 31) represents the number of repetitions of a siloxane unit to which an aliphatic group of 1 is bonded.

M and n in the formulae (b 3) and (b 31) each independently represent an integer of 1 or more, and the sum (m+n) of m and n represents an integer of 2 to 1000. The sum of m and n preferably represents an integer of 3 to 500, more preferably an integer of 3 to 100, and still more preferably an integer of 3 to 50.

The ratio of m/n in the formula (b 3) and the formula (b 31) is preferably 5/95 to 50/50, more preferably 10/90 to 40/60, still more preferably 20/80 to 30/70.

The functional group equivalent (amine equivalent) of the compound represented by the formula (b 3) is preferably 150 to 5000g/mol, more preferably 400 to 4000g/mol, still more preferably 500 to 3000g/mol.

The functional group equivalent means the mass of the compound represented by the formula (b 3) per 1 mol of the functional group (amino group).

Examples of the compounds represented by the general formula (B3) that can be obtained as commercially available products include "X-22-9409", "X-22-1660B", "X-22-161A", "X-22-161B", which are manufactured by Kagaku Kogyo Co., ltd.

When the structural unit (B3) is contained, the ratio of the structural unit (B3) is preferably 0.01 to 15.0 mol%, more preferably 0.5 to 12.0 mol%, and even more preferably 1.0 to 8.0 mol% relative to the total amount of the structural unit (B3), the structural unit Y1B and the structural unit Y2B.

When the structural unit (B3) is contained, the content of the polyorganosiloxane unit is preferably 1 to 20% by mass, more preferably 2 to 18% by mass, and still more preferably 5 to 15% by mass, based on the total of the structural units constituting the imide-amic acid copolymer. If the content of the polyorganosiloxane unit is within the above range, both low retardation and low residual stress can be achieved at a higher level.

Examples of commercially available compounds which can be obtained as the compound represented by the formula (B3) include "X-22-9409" and "X-22-1660B-3" manufactured by Kagaku Kogyo Co., ltd.

[ Method for producing imide-amic acid copolymer ]

The imide-amic acid copolymer of the present invention can be produced by any method, but is preferably obtained by the following method.

The method for producing an imide-amic acid copolymer of the present invention includes the following steps 1 and 2.

(In the formula (1),

Y ² is a group represented by the following general formula (5),

S, t and u are positive integers. )

According to the method for producing an imide-amic acid copolymer of the present invention, since the imide moiety and the amic acid moiety can be controlled to have specific structures, the imide-amic acid copolymer has a polyimide moiety and a polyamic acid moiety according to the thermal imidization reactivity generated by the respective components unlike the conventional imide-amic acid copolymer in which the imide moiety and the amic acid moiety are randomly present, and therefore, an imide-amic acid copolymer which can be expected to be improved in heat resistance, low residual stress, and low linear thermal expansion coefficient can be obtained.

Among them, the method for producing a suitable copolymer of the present invention includes the following steps 1 and 2.

Step 1: a step of reacting a compound providing a structural unit X1A derived from a tetracarboxylic dianhydride with a compound providing a structural unit Y1B derived from a diamine to obtain an imide oligomer

Step 2: a step of reacting the imide oligomer obtained in the step 1 with a compound providing a structural unit X2A derived from tetracarboxylic dianhydride and a compound providing a structural unit Y2B derived from diamine to obtain an imide-amic acid copolymer comprising a repeating unit composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2) represented by the aforementioned formula (1)

Wherein the compound providing the structural unit X1A comprises aromatic tetracarboxylic dianhydride,

The compound providing the structural unit X2A contains an aromatic tetracarboxylic dianhydride different from the structural unit X1A,

The compound providing the structural unit Y1B includes a compound providing the structural unit (B1), the compound providing the structural unit (B1) includes at least any one selected from the group consisting of a compound represented by the following formula (B11), a compound represented by the following formula (B12), and a compound represented by the following formula (B13),

The compound providing the structural unit Y2B includes a compound represented by the following general formula (B2).

According to the production method including the steps 1 and 2, a copolymer capable of forming a film excellent in transparency and heat resistance, low in yellowness, and excellent in low residual stress can be produced.

The method for producing the copolymer of the present invention will be described below.

< Procedure 1 >

Step 1 is a step of reacting a tetracarboxylic acid component constituting an imide part (IM) with a diamine component to obtain an imide oligomer.

The tetracarboxylic acid component constituting the Imide Moiety (IM) is preferably an aromatic tetracarboxylic dianhydride.

More preferably, step 1 is a step of reacting a compound providing a structural unit X1A derived from tetracarboxylic dianhydride with a compound providing a structural unit Y1B derived from diamine to obtain an imide oligomer.

The compound providing the structural unit X1A contains an aromatic tetracarboxylic dianhydride.

The compound providing the structural unit Y1B includes a compound providing the structural unit (B1), and the compound providing the structural unit (B1) includes at least any one selected from the group consisting of the compound represented by the aforementioned formula (B11), the compound represented by the aforementioned formula (B12), and the compound represented by the aforementioned formula (B13).

The tetracarboxylic acid component used in step 1 preferably contains a compound providing the structural unit (A1), and the total amount thereof is preferably used in step 1, and may contain a tetracarboxylic acid component other than the compound providing the structural unit (A1) within a range not to impair the effects of the present invention.

The diamine component used in step 1 preferably contains a compound providing the structural unit (B1), and may contain a diamine component other than the compound providing the structural unit (B1) within a range that does not impair the effects of the present invention.

In step 1, the diamine component is preferably 1.01 to 2 moles, more preferably 1.05 to 1.9 moles, and still more preferably 1.1 to 1.7 moles, relative to the tetracarboxylic acid component.

The method for reacting the tetracarboxylic acid component with the diamine component in step 1 to obtain the imide oligomer is not particularly limited, and a known method can be used.

Specific reaction methods include the following: adding a tetracarboxylic acid component, a diamine component and a reaction solvent into a reactor, stirring for 0.5-30 hours at 10-110 ℃, and then heating to perform imidization; adding diamine component and reaction solvent into a reactor to dissolve the diamine component and the reaction solvent, adding tetracarboxylic acid component, stirring for 0.5-30 hours at 10-110 ℃ according to the need, and heating to perform imidization reaction; the method (3) comprises the steps of charging a tetracarboxylic acid component, a diamine component and a reaction solvent into a reactor, immediately heating the mixture, and carrying out imidization; etc.

In the imidization reaction, the reaction is preferably performed while removing water generated during the production, using a dean-stark trap device or the like. By performing such an operation, the polymerization degree and the imidization rate can be further increased.

In the imidization reaction, a known imidization catalyst may be used. Examples of the imidization catalyst include a base catalyst and an acid catalyst.

Examples of the base catalyst include organic base catalysts such as pyridine, quinoline, isoquinoline, α -methylpyridine, β -methylpyridine, 2, 4-dimethylpyridine, 2, 6-dimethylpyridine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N-dimethylaniline, N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogencarbonate, and sodium hydrogencarbonate.

Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, and the like. The imidization catalyst may be used alone or in combination of 2 or more.

Among the above, from the viewpoint of operability, the base catalyst is preferable, the organic base catalyst is more preferable, 1 or more selected from triethylamine and triethylenediamine is more preferable, and triethylamine is still more preferable.

The temperature of the imidization reaction is preferably 120 to 250 ℃, more preferably 160 to 200 ℃, from the viewpoints of reaction rate, gelation inhibition, and the like. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

The imide oligomer obtained in step 1 preferably has an imide repeating structural unit formed from a compound providing the structural unit (A1) and a compound providing the structural unit (B1).

The oligomer obtained in step 1 preferably has amino groups at both ends of the main chain of the molecular chain.

According to the above method, a solution containing the imide oligomer dissolved in a solvent is obtained. In the solution containing the imide oligomer obtained in the step 1, at least a part of the components used as the tetracarboxylic acid component and the diamine component in the step 1 may be contained as unreacted monomers within a range that does not impair the effects of the present invention.

< Procedure 2 >

The process 2 in the production method of the present invention is the following process: the imide oligomer obtained in step 1 is reacted with a tetracarboxylic acid component and a diamine component constituting an amic acid moiety (AM 2), to obtain an imide-amic acid copolymer comprising a repeating unit represented by the above formula (1) and comprising an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2).

The tetracarboxylic acid component constituting the amic acid moiety (AM 2) used in step2 is preferably an aromatic tetracarboxylic dianhydride.

More preferably, step 2 is a step of reacting a compound providing a structural unit X2A derived from tetracarboxylic dianhydride with a compound providing a structural unit Y2B derived from diamine to obtain an imide-amic acid copolymer.

The compound providing the structural unit X2A contains an aromatic tetracarboxylic dianhydride.

The compound for providing the structural unit Y2B includes a compound for providing the structural unit (B2), and the compound for providing the structural unit (B2) includes a compound represented by the general formula (B2), preferably a compound represented by the general formula (B21).

The tetracarboxylic acid component used in step 2 preferably contains a compound providing the structural unit (A2), and may contain a tetracarboxylic acid component other than the compound providing the structural unit (A2) within a range that does not impair the effects of the present invention. Examples of the tetracarboxylic acid component other than the compound providing the structural unit (A2) include a compound providing the structural unit (A1), but the tetracarboxylic acid component used in the step 2 preferably does not contain a compound providing the structural unit (A1). The total amount of the compound providing the structural unit (A2) is preferably used in step 2.

The diamine component used in step 2 preferably contains a compound providing the structural unit (B2), and may contain a diamine component other than the compound providing the structural unit (B2) within a range that does not impair the effects of the present invention.

When the polyorganosiloxane unit is introduced into the present imide-amic acid copolymer after the completion of the step 2, the resulting copolymer may be reacted with a diamine containing the polyorganosiloxane unit or a tetracarboxylic dianhydride, preferably a diamine containing the polyorganosiloxane unit, and more preferably a compound having a structural unit (B3).

The method for reacting the tetracarboxylic acid component with the imide oligomer obtained in step1 in step 2 to obtain an imide-amic acid copolymer is not particularly limited, and a known method can be used.

Specific reaction methods include the following: the method (1) comprising charging the imide oligomer, the tetracarboxylic acid component, the diamine component and the solvent obtained in the step 1 into a reactor, and stirring the mixture at 0 to 120℃and preferably at 5 to 80℃for 1 to 72 hours; a method (2) wherein the imide oligomer obtained in the step 1 and a solvent are put into a reactor to be dissolved, and then a tetracarboxylic acid component and a diamine component are put into the reactor and stirred at 0 to 120℃and preferably at 5 to 80℃for 1 to 72 hours; etc.

In the case of a reaction at 80 ℃ or lower, the molecular weight of the copolymer obtained in step 2 does not change depending on the temperature history during polymerization, and the progress of thermal imidization can be suppressed, so that the copolymer can be stably produced.

According to the above method, a copolymer solution containing the imide-amic acid copolymer dissolved in a solvent is obtained.

The concentration of the copolymer in the resulting copolymer solution is usually in the range of 1 to 50% by mass, preferably 3 to 35% by mass, more preferably 5 to 30% by mass.

The number average molecular weight of the imide-amic acid copolymer obtained in the production method of the present invention is preferably 5000 to 500000 from the viewpoint of the mechanical strength of the obtained polyimide film. From the same viewpoint, the weight average molecular weight (Mw) is preferably 10000 to 800000, more preferably 100000 ～ 300000. The number average molecular weight of the copolymer can be obtained from, for example, a standard polymethyl methacrylate (PMMA) conversion measured by gel filtration chromatography.

Next, raw materials and the like used in the present production method will be described.

< Tetracarboxylic acid component >

As the tetracarboxylic acid component used as a raw material of the imide-amic acid copolymer in the present production method, a compound providing each structural unit described in the above < each structural unit of the imide-amic acid copolymer > structural unit XIA and structural unit X2A is preferably used. For example, the compound providing the structural unit (A1) may be a compound represented by the formula (A1), but the present invention is not limited thereto, and may be a derivative thereof within a range where the same structural unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the compound represented by the formula (a 1) and an alkyl ester of the tetracarboxylic acid. As the compound which provides the structural unit (A1), a compound represented by the formula (A1) is preferable.

Similarly, examples of the compound providing the structural unit (A2) include a compound represented by the formula (a 21), a compound represented by the formula (a 22), a compound represented by the formula (a 23), a compound represented by the formula (a 24), and a compound represented by the formula (a 25), but the present invention is not limited thereto, and the compound may be a derivative thereof within a range where the same structural unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the compound represented by any one of the formulas (a 21) to (a 25) and an alkyl ester of the tetracarboxylic acid. As the compound providing the structural unit (A2), compounds represented by any one of the formulas (a 21) to (a 25) are preferable.

The molar ratio of the compound providing the structural unit (A1) to the compound providing the structural unit (A2) [ compound (A1)/(A2) ] in the tetracarboxylic acid component used as the starting material of the imide-amic acid copolymer in the present production method is preferably 10/90 to 55/45, more preferably 15/85 to 50/50, still more preferably 20/80 to 45/55.

The total ratio of the compounds providing the structural units (a 21) to (a 25) among the compounds providing the structural units (A2) is preferably 45 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol% or less.

The tetracarboxylic acid component used as a raw material of the imide-amic acid copolymer may contain 1 or 2 or more compounds other than the compound providing the structural unit (A1), the compound providing the structural unit (a 21), the compound providing the structural unit (a 22), the compound providing the structural unit (a 23), the compound providing the structural unit (a 24), and the compound providing the structural unit (a 25).

< Diamine component >

The molar ratio of the compound for providing the structural unit (B1) to the compound for providing the structural unit (B2) [ compound (B1)/(B2) ] in the diamine component used as the starting material of the imide-amic acid copolymer in the present production method is preferably 10/90 to 55/45, more preferably 20/80 to 50/50, still more preferably 25/75 to 45/55.

The compound providing the structural unit (B1) is preferably 1 or more selected from the group consisting of a compound providing the structural unit (B11), a compound providing the structural unit (B12), and a compound providing the structural unit (B13). The total ratio of the compounds providing the structural units (B11) to (B13) among the compounds providing the structural units (B1) is preferably 45 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol% or less.

As the compound for providing the structural unit (B2), 1 or more compounds for providing the structural unit (B2) are preferable.

The diamine component used as a raw material of the imide-amic acid copolymer may contain compounds other than the compound providing the structural unit (B11), the compound providing the structural unit (B12), the compound providing the structural unit (B13), and the compound providing the structural unit (B2), and the above-mentioned compounds may be 1 kind or 2 kinds or more.

The compound for providing the structural unit (B1) and the compound for providing the structural unit (B2) include diamines, but are not limited thereto, and may be derivatives thereof within the range where the same structural unit is provided. As the derivative, diisocyanate corresponding to diamine is exemplified. As the compound providing the structural unit (B1) and the compound providing the structural unit (B2), diamines are preferable.

In the case where the compound providing the structural unit (B3) is contained in the copolymer, the compound providing the structural unit (B3) is preferably contained in an amount of 0.01 to 15.0 mol%, more preferably 0.5 to 12.0 mol%, still more preferably 1.0 to 8.0 mol% based on the total amount of the compound providing the structural unit (B3) and the diamine component.

In the present invention, the ratio of the amount of the tetracarboxylic acid component to the amount of the diamine component to be added in the whole steps of the production of the copolymer including the step 1, the step 2, and the step 2 after completion of the step and the reaction step with other components such as the compound providing the structural unit (B3) is preferably 0.9 to 1.1 mol based on 1 mol of the tetracarboxylic acid component.

< Blocking agent >

In the present invention, in addition to the tetracarboxylic acid component and the diamine component, a capping agent may be used in the production of the imide-amic acid copolymer. It is preferable to use a capping agent in the reaction step with other components such as the compound providing the structural unit (B3) after the completion of step 2 or step 2.

As the blocking agent, monoamines or dicarboxylic acids are preferable. The amount of the blocking agent to be introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. As monoamine type blocking agents, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline and the like are recommended. Among these, benzylamine and aniline can be suitably used. The dicarboxylic acid-based capping agent is preferably a dicarboxylic acid, and a part of the dicarboxylic acid may be closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2, 3-benzophenone dicarboxylic acid, 3, 4-benzophenone dicarboxylic acid, cyclopentane-1, 2-dicarboxylic acid, 4-cyclohexene-1, 2-dicarboxylic acid, and the like are recommended. Among these, phthalic acid and phthalic anhydride can be suitably used.

< Solvent >

The solvent used in the method for producing the copolymer of the present invention may be one which can dissolve the imide-amic acid copolymer produced. Examples thereof include aprotic solvents, phenolic solvents, ether solvents, and carbonate solvents.

Specific examples of the aprotic solvent include amide solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1, 3-dimethylimidazolidone, tetramethylurea, lactone solvents such as γ -butyrolactone and γ -valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphoric triamide, sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide and sulfolane, ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone and methylcyclohexanone, and ester solvents such as (2-methoxy-1-methylethyl) acetate.

Specific examples of the phenol-based solvent include phenol, o-cresol, m-cresol, p-cresol, 2, 3-xylenol, 2, 4-xylenol, 2, 5-xylenol, 2, 6-xylenol, 3, 4-xylenol, and 3, 5-xylenol.

Specific examples of the ether solvent include 1, 2-dimethoxyethane, bis (2-methoxyethyl) ether, 1, 2-bis (2-methoxyethoxy) ethane, bis [ 2- (2-methoxyethoxy) ethyl ] ether, tetrahydrofuran, and 1, 4-dioxane.

Specific examples of the carbonate-based solvent include diethyl carbonate, methylethyl carbonate, ethylene carbonate, propylene carbonate, and the like.

Among the above reaction solvents, an amide-based solvent or a lactone-based solvent is preferable, an amide-based solvent is more preferable, and N-methyl-2-pyrrolidone is still more preferable. The above reaction solvents may be used alone or in combination of 2 or more.

[ Varnish ]

The varnish of the present invention is obtained by dissolving the imide-amic acid copolymer of the present invention, which is a precursor of a polyimide resin, in an organic solvent. That is, the varnish of the present invention comprises the copolymer of the present invention and an organic solvent, and the copolymer is dissolved in the organic solvent.

The organic solvent is not particularly limited as long as it dissolves the copolymer of the present invention, and as the solvent used in the production of the copolymer of the present invention, it is preferable to use 2 or more of the above compounds alone or in combination.

The varnish of the present invention may be the copolymer solution itself, or may be obtained by adding a diluting solvent to the copolymer solution.

The varnish of the present invention may further contain an imidization catalyst and a dehydration catalyst from the viewpoint of efficiently imidizing the amic acid moiety in the copolymer of the present invention. The imidization catalyst may be any imidization catalyst having a boiling point of 40 ℃ or more and 180 ℃ or less, and an amine compound having a boiling point of 180 ℃ or less is preferable. If the imidization catalyst has a boiling point of 180 ℃ or less, there is no fear of coloration of the film during drying at high temperature after formation of the film, and there is no fear of deterioration of the appearance. In addition, if the imidization catalyst has a boiling point of 40 ℃ or higher, the possibility of sufficient pre-evaporation of imidization can be avoided.

Examples of amine compounds suitable for use as imidization catalysts include pyridine and picoline. The imidization catalyst may be used alone or in combination of 2 or more.

Examples of the dehydration catalyst include anhydrides such as acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride and trifluoroacetic anhydride; carbodiimide compounds such as dicyclohexylcarbodiimide; etc. They may be used alone or in combination of 2 or more.

The copolymer contained in the varnish of the present invention has solvent solubility, and thus, a varnish of high concentration can be formed. The varnish of the present invention preferably contains 3 to 40% by mass, more preferably 5 to 40% by mass, and still more preferably 10 to 30% by mass of the copolymer of the present invention. The viscosity of the varnish is preferably 0.1 to 100pa·s, more preferably 0.1 to 20pa·s. The viscosity of the varnish is a value measured at 25℃using an E-type viscometer.

The varnish of the present invention may contain various additives such as an inorganic filler, an adhesion promoter, a release agent, a flame retardant, an ultraviolet stabilizer, a surfactant, a leveling agent, a defoaming agent, a Ō optical brightening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer, within a range that does not impair the required properties of the polyimide film.

The method for producing the varnish of the present invention is not particularly limited, and a known method can be applied.

[ Polyimide film ]

The polyimide film of the present invention comprises: polyimide resins obtained by imidizing the amic acid sites in the imide-amic acid copolymers of the present invention. Therefore, the polyimide film of the present invention is excellent in transparency and heat resistance, has a low yellowness, and shows a low residual stress. The polyimide film of the present invention has suitable physical properties as described above.

The polyimide film of the present invention can be produced by using a varnish obtained by dissolving the copolymer in an organic solvent.

The method for producing a polyimide film using the varnish of the present invention is not particularly limited, and a known method can be used. For example, a polyimide film can be produced by applying the varnish of the present invention to a smooth support such as a glass plate, a metal plate, or a plastic, or by molding the varnish into a film, then removing an organic solvent such as a reaction solvent or a dilution solvent contained in the varnish by heating to obtain a copolymer film, imidizing (dehydrating and ring-closing) the amic acid sites of the copolymer in the copolymer film by heating, and then peeling the copolymer film from the support.

The weight average molecular weight (Mw) of the polyimide resin contained in the polyimide film of the present invention is preferably 10000 to 800000, more preferably 30000 to 500000, further preferably 50000 to 400000, further preferably 100000 ～ 300000, from the viewpoint of the mechanical strength of the film. The number average molecular weight of the copolymer can be obtained from, for example, a standard polymethyl methacrylate (PMMA) conversion measured by gel filtration chromatography.

The heating temperature for drying the varnish of the present invention to obtain a copolymer film is preferably 50 to 150 ℃. The heating temperature at the time of imidizing the copolymer of the present invention by heating is preferably 200 to 500 ℃, more preferably 250 to 450 ℃, still more preferably 300 to 400 ℃. The heating time is usually 1 minute to 6 hours, preferably 5 minutes to 2 hours, and more preferably 15 minutes to 1 hour.

The heating atmosphere includes air, nitrogen, oxygen, hydrogen, and a nitrogen/hydrogen mixture, but in order to suppress coloring of the polyimide resin obtained, nitrogen having an oxygen concentration of 100ppm or less and a nitrogen/hydrogen mixture containing hydrogen having a hydrogen concentration of 0.5% or less are preferable.

The method of imidization is not limited to thermal imidization, and chemical imidization may be applied.

The thickness of the polyimide film of the present invention can be appropriately selected depending on the application, etc., and is preferably 1 to 250. Mu.m, more preferably 5 to 100. Mu.m, still more preferably 5 to 50. Mu.m. The thickness of 1 to 250 μm makes it possible to use the film as a self-standing film.

The thickness of the polyimide film can be easily controlled by adjusting the solid concentration and viscosity of the varnish.

< Physical Property values of polyimide film >)

By using the imide-amic acid copolymer of the present invention, a polyimide film having excellent transparency and heat resistance, low yellowness, and further exhibiting low residual stress can be formed. The film has suitable physical properties as described below.

When a film having a thickness of 10 μm is formed, the total light transmittance is preferably 85% or more, more preferably 86% or more, and still more preferably 87% or more.

When a film having a thickness of 10.+ -.3. Mu.m, the Yellowness Index (YI) is preferably 15.0 or less, more preferably 13.0 or less, still more preferably 12.0 or less, still more preferably 11.0 or less.

The glass transition temperature (Tg) is preferably 400℃or higher, more preferably 420℃or higher, and still more preferably 430℃or higher.

The residual stress is preferably 35MPa or less, more preferably 30MPa or less, and still more preferably 24MPa or less.

The linear thermal expansion coefficient (in the range of 100 to 400 ℃) is preferably 40 ppm/DEG C or less, more preferably 30 ppm/DEG C or less, and still more preferably 20 ppm/DEG C or less.

The physical property values in the present invention can be specifically measured by the methods described in examples.

The polyimide film of the present invention is suitable for use as a film for various members such as color filters, flexible displays, semiconductor components, and optical members. The polyimide film of the present invention is particularly suitable for use as a substrate for image display devices such as liquid crystal displays and OLED displays.

Examples

Hereinafter, the present invention will be specifically described with reference to examples. Wherein the invention is not limited by these examples.

The physical properties of the films obtained in examples and comparative examples were measured by the methods shown below.

(1) Film thickness

Film thickness was measured using a Mitutoyo Corporation micrometer.

(2) Total light transmittance, yellow Index (YI)

Total light transmittance and YI according to JIS K7105: 1981. the color/turbidity was measured by using a color/turbidity simultaneous measuring instrument "COH7700" manufactured by Nippon electric color industry Co.

(3) Haze degree

Measurement according to JIS K7361-1: 1997. the color/turbidity simultaneous measurement instrument "COH7700" manufactured by Nippon electric color industry Co., ltd.

(4) Glass transition temperature (Tg)

Using a thermo-mechanical analysis device "TMA/SS6100" manufactured by HITACHI HIGH-TECH SCIENCE co., ltd. In the stretching mode, the temperature was raised to a temperature sufficient for eliminating residual stress under conditions of a sample size of 3mm×20mm, a load of 0.1N, a nitrogen gas flow (flow rate of 200 mL/min), and a temperature raising rate of 10 ℃/min, the residual stress was eliminated, and then cooled to room temperature. Thereafter, the elongation of the test piece was measured under the same conditions as in the treatment for eliminating the residual stress, and the point of inflection of the elongation was found to be the glass transition temperature.

(5) Coefficient of linear thermal expansion (CTE)

Using a thermo-mechanical analysis device "TMA/SS6100" manufactured by HITACHI HIGH-TECH SCIENCE co., ltd. In the stretching mode, the temperature was raised to a temperature sufficient for eliminating residual stress under conditions of a sample size of 3mm×20mm, a load of 0.1N, a nitrogen gas flow (flow rate of 200 mL/min), and a temperature raising rate of 10 ℃/min, the residual stress was eliminated, and then cooled to room temperature. Thereafter, the test piece elongation was measured under the same conditions as in the treatment for eliminating residual stress, and the CTE was obtained at 100 to 400 ℃.

(6) 1% Weight loss temperature (Td 1%)

The apparatus "TG/DTA6200" was measured simultaneously using a differential thermogravimetry system manufactured by HITACHI HIGH-TECH SCIENCE co. The sample was heated from 40 to 550℃at a heating rate of 10℃per minute, and the temperature at which the weight was reduced by 1% was regarded as a 1% weight loss temperature, compared with the weight at 300 ℃. The larger the value of the weight loss temperature is, the more excellent.

(7) Tensile Strength, tensile modulus

Tensile Strength, tensile modulus according to JIS K7127: 1999. measured using a tensile tester "Stroggraph VG-1E" manufactured by Toyo Seisakusho Co. The pitch of the chucks was set to 50mm, the test piece size was set to 10 mm. Times.70 mm, and the test speed was set to 20 mm/min.

(8) Residual stress

The varnishes obtained in examples and comparative examples were applied to 4-inch silicon wafers of 525 μm.+ -. 25 μm in thickness, which were previously measured for "warpage", using a residual stress measuring device "FLX-2320" manufactured by KLA-Tencor Co., ltd. With a spin coater, and prebaked. Then, a silicon wafer having a polyimide film with a thickness of 6 to 15 μm after curing was produced by performing a heat curing treatment at 400℃for 60 minutes (a heating rate of 5 ℃/min) in a nitrogen atmosphere using a hot air dryer. The warpage amount of the wafer was measured by using the residual stress measuring device, and residual stress generated between the silicon wafer and the polyimide film was evaluated.

The tetracarboxylic acid component and the diamine component used in examples and comparative examples, abbreviations thereof and the like are as follows.

< Tetracarboxylic acid component >

BPAF:9, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (JFE Chemical Corporation; compound represented by formula (a 1))

S-BPDA:3,3', 4' -Biphenyltetracarboxylic dianhydride (Compound represented by Mitsubishi chemical Co., ltd. (a 21 s))

< Diamine component >

4,4' -DDS:4,4' -diaminodiphenyl sulfone (Seika Co., ltd., compound represented by formula (b 111))

TFMB:2,2' -bis (trifluoromethyl) benzidine (Seika Co., ltd.; compound represented by formula (b 122))

4-BAAB: 4-aminophenyl-4-aminobenzoate (Compound represented by the formula (b 21) manufactured by Nippon pure pharmaceutical Co., ltd.)

Abbreviations for solvents and catalysts used in examples and comparative examples, and the like, are as follows.

NMP: n-methyl-2-pyrrolidone (manufactured by Tokyo pure medicine industry Co., ltd.)

TEA: triethylamine (manufactured by Kanto chemical Co., ltd.)

Example 1

A500 mL five-necked round-bottomed flask equipped with a stainless steel half-moon shaped stirring blade, a nitrogen inlet pipe, a dean-Stark trap equipped with a condenser, a thermometer, and a glass end cap was charged with 4,4' -DDS 9.932g (0.040 mol) and NMP 46.380g, and the mixture was stirred at a temperature of 70℃in the system under a nitrogen atmosphere at a rotation speed of 200rpm to obtain a solution.

To this solution, 13.753g (0.030 mol) of BPAF and 11.595g of NMP were added simultaneously, and then 0.152g of TEA as an imidization catalyst was charged, and the mixture was heated in a covered heater to raise the temperature in the reaction system to 190℃over about 20 minutes. The distilled components were collected, the rotation speed was adjusted according to the viscosity rise, and the temperature in the reaction system was kept at 190℃and refluxed for 1 hour. Thereafter, 95.849g of NMP was added, and the temperature in the reaction system was cooled to 50℃to obtain a solution containing an oligomer having an imide repeating structural unit.

To the resulting solution, 20.595g (0.070 mol), 4-BAAB13.695g (0.060 mol) and 16.858g of NMP were added simultaneously, and stirred at 50℃for 5 hours. Thereafter, NMP was added so that the solid content concentration became about 15 mass% and homogenized, thereby obtaining a varnish containing a copolymer having an imide repeating structural unit and an amic acid structural unit.

Then, the obtained varnish was applied to a glass plate by spin coating, and the resultant was kept at 80℃for 20 minutes on a hot plate, and then heated at 430℃for 60 minutes in a hot air dryer under a nitrogen atmosphere, whereby the solvent was evaporated to obtain a polyimide film. The results are shown in Table 1.

Example 2

A varnish having a solid content of about 15% by mass was obtained in the same manner as in example 1, except that the amount of BPAF was changed from 13.753 (0.030 mol) to 9.169g (0.020 mol) and the amount of s-BPDA was changed from 20.595g (0.070 mol) to 23.538g (0.080 mol).

Using the varnish obtained, a film was obtained in the same manner as in example 1.

Example 3

A varnish having a solid content of about 15% by mass was obtained in the same manner as in example 1, except that the amount of BPAF was changed from 13.753 (0.030 mol) to 9.169g (0.020 mol), the amount of s-BPDA was changed from 20.595g (0.070 mol) to 23.538g (0.080 mol), the amount of 4,4' -DDS was changed from 9.932 (0.040 mol) to 7.449g (0.030 mol), and the amount of 4-BAAB was changed from 13.695 (0.060 mol) to 15.978g (0.070 mol).

Example 4

A polyimide varnish having a solid content of about 15 mass% was obtained in the same manner as in example 1, except that the content of 4,4' -DDS 9.932g (0.040 mol) was changed to TFMB 12.810g (0.040 mol).

Example 5

A varnish having a solid content of about 15% by mass was obtained in the same manner as in example 4, except that the amount of BPAF was changed from 13.753 (0.030 mol) to 9.169g (0.020 mol), the amount of s-BPDA was changed from 20.595g (0.070 mol) to 23.538g (0.080 mol), the amount of TFMB was changed from 12.810g (0.040 mol) to 9.607g (0.030 mol), and the amount of 4-BAAB was changed from 13.695 (0.060 mol) to 15.978g (0.070 mol).

Comparative example 1

A500 mL five-necked round-bottomed flask equipped with a stainless steel half-moon shaped stirring blade, a nitrogen inlet pipe, a dean-Stark trap equipped with a condenser, a thermometer, and a glass end cap was charged with 4 to BAAB 22.825g (0.100 mol) and 167.190g of NMP, and the mixture was stirred at a temperature of 50℃in the system under a nitrogen atmosphere at a rotation speed of 200rpm to obtain a solution.

To this solution, s-BPDA29.422g (0.100 mol) and NMP 41.798g were added simultaneously, and stirred at room temperature for 5 hours.

Thereafter, 87.078g of NMP was added so that the solid content became about 15 mass%, and the mixture was stirred for about 1 hour to homogenize the mixture, thereby obtaining a polyamic acid (PAA) varnish.

The polyamic acid contained in the varnish obtained in comparative example 1 had only the repeating structural units of amic acid formed from s-BPDA and 4 to BAAB.

Comparative example 2

A polyamic acid (PAA) varnish having a solid content of about 15% by mass was obtained in the same manner as in comparative example 1, except that the concentration of s-BPDA 29.422g (0.100 mol) was changed to BPAF 45.843g (0.100 mol).

The polyamic acid contained in the varnish obtained in comparative example 1 had only the amic acid repeating structural unit formed from BPAF and 4 to BAAB.

Comparative example 3

A500 mL five-necked round-bottomed flask equipped with a stainless steel half-moon shaped stirring blade, a nitrogen gas inlet pipe, a dean-Stark trap equipped with a condenser, a thermometer, and a glass end cap was charged with 4,4' -DDS 9.932g (0.040 mol), 4-BAAB 13.695g (0.060 mol), and NMP 139.141g, and the mixture was stirred at a temperature of 50℃in the system under a nitrogen atmosphere at a rotation speed of 200rpm to obtain a solution.

To this solution, 13.753g (0.030 mol) of BPAF, 20.595g (0.070 mol) of s-BPDA, and 34.785g of NMP were added simultaneously, and the mixture was stirred at room temperature for 5 hours. Thereafter, NMP was added so that the solid content concentration became about 15 mass%, and the resultant was homogenized, thereby obtaining a polyamic acid (PAA) varnish.

The polyamic acid contained in the varnish obtained in comparative example 3 had only amic acid repeating structural units formed of BPAF, s-BPDA, 4' -DDS, and 4-BAAB.

TABLE 1

As shown in table 1, it can be seen that: for polyimide films obtained from the imide-amic acid copolymers of examples having specific imide repeating structural units and amic acid structural units, the residual stress and linear thermal expansion coefficients are low, the transparency and heat resistance are also excellent, and the yellowness is also low.

The polyimide film of example 1 maintains transparency and low yellowness, and is excellent in heat resistance in particular, and also has low residual stress and linear thermal expansion coefficient, as compared with the polyimide film of comparative example 3 obtained from polyamic acid, although the polyimide film of example 1 has the same raw material composition as that of the polyimide film of comparative example 3.

Claims

1. An imide-amic acid copolymer comprising: a repeating unit represented by the following formula (1) and composed of an Imide Moiety (IM), an amic acid moiety (AM 1) and an amic acid moiety (AM 2),

In the formula (1), the components are as follows,

Y ² is a group represented by the following general formula (5),

S, t and u are positive integers,

In the formula (3), Z ¹ represents a single bond or a group represented by-O-,

In the formula (4), R independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms,

In the formula (5), Z ²、Z³ is a group represented by-COO-or-OCO-, R ¹、R²、R³ is a 1-valent organic group having 1 to 20 carbon atoms, h, i, j, k is an integer of 0 to 4,

The Imide Moiety (IM) has: structural units X1A derived from tetracarboxylic dianhydride and structural units Y1B derived from diamine, the amic acid moiety (AM 1) having: structural unit X2A derived from tetracarboxylic dianhydride, structural unit Y1B derived from diamine, the amic acid moiety (AM 2) having: structural units X2A derived from tetracarboxylic dianhydride, structural units Y2B derived from diamine,

The structural unit X1A includes: a structural unit (A1) derived from a compound represented by the following formula (A1),

The structural unit X2A comprises: structural units (A2) derived from aromatic tetracarboxylic dianhydrides (A2),

The structural unit (A2) contains at least 1 selected from the group consisting of a structural unit (A21) derived from a compound represented by the following formula (a 21), a structural unit (A22) derived from a compound represented by the following formula (a 22), a structural unit (A23) derived from a compound represented by the following formula (a 23), a structural unit (A24) derived from a compound represented by the following formula (a 24), and a structural unit (A25) derived from a compound represented by the following formula (a 25),

。

2. The imide-amic acid copolymer of claim 1 wherein s is 1 to 50 and t is 1 to 50.

3. The imide-amic acid copolymer of claim 1 or 2, wherein u is 5 to 200.

4. The imide-amic acid copolymer according to claim 1 or 2, wherein X ¹ is a group represented by the following formula (6),

5. The imide-amic acid copolymer according to claim 1 or 2, wherein X ² is a group represented by the following formula (7),

6. The imide-amic acid copolymer according to claim 1 or 2, wherein,

The structural unit Y2B includes: a structural unit (B2) derived from a compound represented by the following general formula (B2),

In the formula (b 12), Z ¹ represents a single bond or a group represented by-O-,

In the formula (b 13), R independently represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 5 carbon atoms,

In the formula (b 2), Z ²、Z³ is a group represented by-COO-or-OCO-, R ¹、R²、R³ is a 1-valent organic group having 1 to 20 carbon atoms, and h, i, j, k is an integer of 0 to 4.

7. The imide-amic acid copolymer according to claim 6 further comprising structural units (B3) derived from a compound represented by the following general formula (B3),

In the formula (b 3), Z ⁴ and Z ⁵ each independently represent an aliphatic group having a valence of 2, or an aromatic group having a valence of 2, R ⁴ and R ⁵ each independently represent an aromatic group having a valence of 1, or an aliphatic group having a valence of 1, R ⁶ and R ⁷ each independently represent an aliphatic group having a valence of 1, R ⁸ and R ⁹ each independently represent an aliphatic group having a valence of 1, or an aromatic group having a valence of 1, m and n each independently represent an integer of 1 or more, and the sum of m and n represents an integer of 2 to 1000, wherein at least one of R ⁴ and R ⁵ represents an aromatic group having a valence of 1.

8. The imide-amic acid copolymer of claim 7 wherein R ⁴ and R ⁵ are phenyl and R ⁶ and R ⁷ are methyl.

9. The imide-amic acid copolymer according to claim 7 or 8, wherein the content of the polyorganosiloxane unit in the imide-amic acid copolymer is 1 to 20 mass%.

10.A varnish prepared by dissolving the copolymer according to any one of claims 1 to 9 in an organic solvent.

11. A polyimide film comprising a polyimide resin obtained by imidizing the amic acid moiety in the copolymer according to any one of claims 1 to 9.

12. The polyimide film according to claim 11, wherein the polyimide resin has a weight average molecular weight (Mw) of 100000 ～ 300000.

13. A process for producing an imide-amic acid copolymer comprising the following steps 1 and 2,

Step 1: a step of reacting a tetracarboxylic acid component constituting an Imide Moiety (IM) with a diamine component to obtain an imide oligomer;

step 2: a step of reacting the imide oligomer obtained in the step 1 with a tetracarboxylic acid component and a diamine component constituting an amic acid moiety (AM 2) to obtain an imide-amic acid copolymer comprising a repeating unit composed of an Imide Moiety (IM) and amic acid moieties (AM 1) and (AM 2) represented by the following formula (1),

In the formula (1), the components are as follows,

Y ² is a group represented by the following general formula (5),

S, t and u are positive integers,

In the formula (3), Z ¹ represents a single bond or a group represented by-O-,

14. The process for producing an imide-amic acid copolymer according to claim 13 wherein the imide oligomer produced in step 1 has amino groups at both ends of the main chain of the molecular chain.

15. The method for producing an imide-amic acid copolymer according to claim 13 or 14 wherein the molar ratio of the diamine component to the tetracarboxylic acid component in step 1, i.e., diamine/tetracarboxylic acid, is 1.01 to 2.

16. The method for producing an imide-amic acid copolymer according to claim 13 or 14 wherein the copolymer is reacted with a diamine containing a polyorganosiloxane unit after the completion of step 2.