阅读说明：本技术 聚酰亚胺树脂、聚酰亚胺清漆及聚酰亚胺薄膜 (Polyimide resin, polyimide varnish, and polyimide film ) 是由 松丸晃久 广瀬重之 村山智寿 村谷孝博 于 2019-08-16 设计创作，主要内容包括：本发明涉及一种聚酰亚胺树脂,其具有源自四羧酸二酐的结构单元A及源自二胺的结构单元B,结构单元A包含选自由源自式(a-1)所示的化合物的结构单元(A-1)、及源自式(a-2)所示的化合物的结构单元(A-2)组成的组中的至少一种结构单元；结构单元B包含选自由源自通式(b1-1)所示的化合物的结构单元、及源自通式(b2-1)所示的化合物的结构单元组成的组中的至少1种结构单元(B-1),提供能够形成无色透明性优异、进而低延迟量的薄膜的聚酰亚胺树脂、聚酰亚胺清漆及聚酰亚胺薄膜。(式中,X～1～X～4分别独立地表示单键、碳数1～5的亚烷基、碳数2～5的烷叉基、-S-、-SO-、-SO-2-、-O-或-CO-。)(The present invention relates to a polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, the structural unit A containing at least one structural unit selected from the group consisting of a structural unit (A-1) derived from a compound represented by formula (a-1) and a structural unit (A-2) derived from a compound represented by formula (a-2); the structural unit B comprises at least 1 structural unit (B-1) selected from the group consisting of a structural unit derived from a compound represented by the general formula (B1-1) and a structural unit derived from a compound represented by the general formula (B2-1), and provides a polyimide resin, a polyimide varnish, and a polyimide film which are capable of forming a film having excellent colorless transparency and further having a low retardation. (in the formula, X 1 ～X 4 Each independently represents a single bond or a C1-5 subunitAlkyl, alkylidene group with 2-5 carbon atoms, -S-, -SO 2 -, -O-or-CO-. ))

1. A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein,

the structural unit A contains at least 1 structural unit selected from the group consisting of a structural unit (A-1) derived from a compound represented by the following formula (a-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2),

the structural unit B comprises at least 1 structural unit (B-1) selected from the group consisting of a structural unit derived from a compound represented by the following general formula (B1-1) and a structural unit derived from a compound represented by the following general formula (B2-1),

in the formula, X¹～X⁴Independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -S-, -SO₂-, -O-or-CO-.

2. The polyimide resin according to claim 1, wherein the proportion of the structural unit (B-1) in the structural unit B is 5 to 100 mol%.

3. The polyimide resin according to claim 1 or 2, wherein the structural unit A comprises a structural unit (A-1), and the proportion of the structural unit (A-1) in the structural unit A is 45 to 100 mol%.

4. The polyimide resin according to any one of claims 1 to 3, wherein the structural unit (B-1) comprises at least 1 structural unit selected from the group consisting of a structural unit derived from a compound represented by the following formula (B1-1-1), a structural unit derived from a compound represented by the following formula (B1-1-2), and a structural unit derived from a compound represented by the following formula (B1-1-3),

5. the polyimide resin according to any one of claims 1 to 4, wherein the structural unit B further comprises at least 1 structural unit selected from the group consisting of a structural unit (B-2) derived from a compound represented by the following formula (B-2), a structural unit (B-3) derived from a compound represented by the following formula (B-3), and a structural unit (B-4) derived from a compound represented by the following formula (B-4),

6. the polyimide resin according to claim 5, wherein the total of the structural unit (B-2), the structural unit (B-3), and the structural unit (B-4) in the structural unit B accounts for 5 to 95 mol%.

7. The polyimide resin according to any one of claims 1 to 6, wherein the structural unit A further comprises a structural unit (A-3) derived from a compound represented by the following formula (a-3),

8. a polyimide varnish prepared by dissolving the polyimide resin according to any one of claims 1 to 7 in an organic solvent.

9. A polyimide film comprising the polyimide resin according to any one of claims 1 to 7.

Technical Field

The present invention relates to a polyimide resin, a polyimide varnish, and a polyimide film.

Background

Various uses of polyimide resins in the fields of electric/electronic components and the like have been studied. For example, for the purpose of weight reduction and flexibility of devices, it is desired to replace glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates, and studies on polyimide films suitable for the plastic substrates have been advanced. The polyimide film for such applications is required to have colorless transparency.

Further, as properties required for the polyimide film, a small retardation due to birefringence and a low retardation are required.

As a polyimide resin providing a film with reduced birefringence, patent document 1 discloses a polyimide resin obtained using a diamine (for example, m-phenylenediamine) in which at least one of the amino groups is bonded at a meta position with respect to the main chain.

As a polyimide resin for providing a film excellent in heat resistance, light transmittance, low linear expansion coefficient, and low retardation, patent document 2 discloses a polyimide resin containing a tetracarboxylic acid residue and a diamine residue having a specific structure and containing a tetracarboxylic acid residue and/or a diamine residue having a bent portion, specifically, a polyimide resin obtained using 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride, 3 ', 4, 4' -bicyclohexatetracarboxylic dianhydride, pyromellitic anhydride, 2 '-bis (trifluoromethyl) benzidine, and 4, 4' -diaminodiphenylsulfone.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 8-134211

Patent document 2: international publication No. 2015/125895

Disclosure of Invention

Problems to be solved by the invention

As described above, various properties are required for the polyimide film, but it is not easy to satisfy these properties at the same time.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a polyimide resin which can form a film having excellent colorless transparency and further having a low retardation, and a polyimide varnish and a polyimide film comprising the polyimide resin.

Means for solving the problems

The present inventors have found that a polyimide resin containing a combination of specific structural units can solve the above problems, and have completed the present invention.

That is, the present invention relates to the following [1] to [9 ].

[1]

A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein,

the structural unit A contains at least 1 structural unit selected from the group consisting of a structural unit (A-1) derived from a compound represented by the following formula (a-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2),

the structural unit B contains at least 1 structural unit (B-1) selected from the group consisting of a structural unit derived from a compound represented by the following general formula (B1-1) and a structural unit derived from a compound represented by the following general formula (B2-1).

(in the formula, X¹～X⁴Independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, S-, -SO₂-, -O-or-CO-. )

[2]

The polyimide resin according to the above [1], wherein the proportion of the structural unit (B-1) in the structural unit B is 5 to 100 mol%.

[3]

The polyimide resin according to the above [1] or [2], wherein the structural unit A comprises a structural unit (A-1), and the proportion of the structural unit (A-1) in the structural unit A is 45 to 100 mol%.

[4]

The polyimide resin according to any one of the above [1] to [3], wherein the structural unit (B-1) comprises at least 1 structural unit selected from the group consisting of a structural unit derived from a compound represented by the following formula (B1-1-1), a structural unit derived from a compound represented by the following formula (B1-1-2), and a structural unit derived from a compound represented by the following formula (B1-1-3).

[5]

The polyimide resin according to any one of the above [1] to [4], wherein the structural unit B further comprises at least 1 structural unit selected from the group consisting of a structural unit (B-2) derived from a compound represented by the following formula (B-2), a structural unit (B-3) derived from a compound represented by the following formula (B-3), and a structural unit (B-4) derived from a compound represented by the following formula (B-4).

[6]

The polyimide resin according to [5], wherein the total proportion of the structural unit (B-2), the structural unit (B-3) and the structural unit (B-4) in the structural unit B is 5 to 95 mol%.

[7]

The polyimide resin according to any one of the above [1] to [6], wherein the structural unit A further comprises a structural unit (A-3) derived from a compound represented by the following formula (a-3).

[8]

A polyimide varnish obtained by dissolving the polyimide resin according to any one of the above [1] to [7] in an organic solvent.

[9]

A polyimide film comprising the polyimide resin according to any one of the above [1] to [7 ].

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention provides a polyimide resin capable of forming a film having excellent colorless transparency and a low retardation, and a polyimide varnish and a polyimide film comprising the polyimide resin.

Detailed Description

[ polyimide resin ]

The polyimide resin of the present invention has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, the structural unit A containing at least 1 structural unit selected from the group consisting of a structural unit (A-1) derived from a compound represented by the following formula (a-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2),

the structural unit B contains at least 1 structural unit (B-1) selected from the group consisting of a structural unit derived from a compound represented by the following general formula (B1-1) and a structural unit derived from a compound represented by the following general formula (B2-1).

(in the formula, X¹～X⁴Independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, S-, -SO₂-, -O-or-CO-. )

< structural Unit A >

The structural unit A is a structural unit derived from tetracarboxylic dianhydride in a polyimide resin, and the structural unit A contains at least 1 structural unit selected from the group consisting of a structural unit (A-1) derived from a compound represented by the following formula (a-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2).

The compound represented by the formula (a-1) is 1,2,4, 5-cyclohexanetetracarboxylic dianhydride.

When the structural unit A contains the structural unit (A-1), the colorless transparency, heat resistance and heat stability of the film are improved.

The compound represented by the formula (a-2) is 4, 4' - (hexafluoroisopropylidene) phthalic anhydride.

When the structural unit a contains the structural unit (a-2), the transparency of the film is improved, and the solubility of the polyimide in an organic solvent is improved.

The structural unit A may contain both the structural unit (A-1) and the structural unit (A-2), preferably contains either the structural unit (A-1) or the structural unit (A-2), and more preferably contains the structural unit (A-1).

When the structural unit a includes the structural unit (a-1) and the structural unit (a-2), the total ratio of the structural units (a-1) and (a-2) in the structural unit a is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total ratio of the structural units (A-1) and (A-2) is not particularly limited, i.e., 100 mol%.

When the structural unit a includes the structural unit (a-1), the ratio of the structural unit (a-1) in the structural unit a is preferably 45 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, i.e., 100 mol%. Similarly, the proportion of the structural unit (A-1) in the structural unit A is preferably 45 to 100 mol%, more preferably 70 to 100 mol%, still more preferably 90 to 100 mol%, and particularly preferably 99 to 100 mol%.

When the structural unit a includes the structural unit (a-2), the ratio of the structural unit (a-2) in the structural unit a is preferably 45 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, i.e., 100 mol%. Similarly, the proportion of the structural unit (a-2) in the structural unit a is preferably 45 to 100 mol%, more preferably 70 to 100 mol%, further preferably 90 to 100 mol%, and particularly preferably 99 to 100 mol%.

The structural unit A may further contain a structural unit (A-3) derived from a compound represented by the following formula (a-3).

The compound represented by the formula (a-3) is norbornane-2-spiro- α -cyclopentanone- α' -spiro-2 ″ -norbornane-5, 5 ″,6,6 ″ -tetracarboxylic dianhydride. When the structural unit A contains the structural unit (A-3), the colorless transparency of the film is improved.

When the structural unit a includes the structural unit (a-3), the ratio of the structural unit (a-13) in the structural unit a is preferably 55 mol% or less, and more preferably 30 mol% or less.

When the structural unit A includes the structural unit (A-3), the structural unit A preferably includes the structural unit (A-1) and the structural unit (A-3), and more preferably includes the structural unit (A-1) and the structural unit (A-3).

The structural unit A may contain structural units other than the structural units (A-1) to (A-3) within a range not impairing the effects of the present invention. Examples of the tetracarboxylic dianhydride which provides such a structural unit include, but are not particularly limited to, aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride, 3,3 ', 4,4 ' -diphenylsulfone tetracarboxylic dianhydride, 3,3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride, 2 ', 3,3 ' -benzophenone tetracarboxylic dianhydride, 4,4 ' -oxydiphthalic anhydride, 3,3 ', 4,4 ' -biphenyltetracarboxylic dianhydride, 2,3,3 ', 4 ' -biphenyltetracarboxylic dianhydride, and 2,2 ', 3,3 ' -biphenyltetracarboxylic dianhydride; alicyclic tetracarboxylic acid dianhydrides such as 1,2,3, 4-cyclobutanetetracarboxylic acid dianhydride, 1,2,4, 5-cyclopentanetetracarboxylic acid dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic acid dianhydride, and dicyclohexyltetracarboxylic acid dianhydride; and aliphatic tetracarboxylic acid dianhydrides such as 1,2,3, 4-butanetetracarboxylic acid dianhydride.

In the present specification, an aromatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing 1 or more aromatic rings, an alicyclic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing 1 or more alicyclic rings and no aromatic rings, and an aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing no aromatic rings and no alicyclic rings.

The structural units other than the structural units (A-1) to (A-3) optionally contained in the structural unit A are optionally 1 or 2 or more.

The structural unit A preferably does not contain structural units other than the structural units (A-1) to (A-3).

< structural Unit B >

The structural unit B is at least 1 structural unit (B-1) selected from the group consisting of a diamine-derived structural unit in the polyimide resin, a structural unit derived from a compound represented by the following general formula (B1-1), and a structural unit derived from a compound represented by the following general formula (B2-1).

In the formulae (b1-1) and (b2-1), X¹～X⁴Independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, S-, -SO₂-, -O-or-CO-.

When the structural unit B contains the structural unit (B-1), the colorless transparency of the film is improved and the retardation value is reduced. The structural unit (B-1) is optionally 1 or more than 2.

The compound represented by the general formula (b1-1) has the formula (I) represented by the formula¹And X²To which 3 benzene rings are attached and X¹And X²A skeleton bonded to the 1-and 3-positions of the central benzene ring, and a compound represented by the general formula (b2-1) having X³And X⁴To which 3 benzene rings are attached and X³And X⁴A skeleton bonded to the 1-and 2-positions of the central benzene ring. By having such a skeleton structure in the structural unit B of the polyimide resin, a film excellent in low retardation can be formed.

X in the general formulae (b1-1) and (b2-1) is a group represented by the formula¹～X⁴Independently preferably C3-C5 alkylidene group (alkylidene) or SO₂-, or-O-, more preferably an alkylidene (alkylidene) group having 3 to 5 carbon atoms, or-O-, still more preferably an isopropylidene group, or-O-, and still more preferably an isopropylidene group.

X in the formula (b1-1)¹And X²May have different groups, respectively, but preferably the same group. Similarly, X in the formula (b2-1)³And X⁴May have different groups, respectively, but preferably the same group.

Relative to X bonded to benzene ring bonded to each amino group¹～X⁴In any of the general formulae (b1-1) and (b2-1), the amino group is preferably bonded to the para-or meta-position of the benzene ring.

The structural unit (B-1) preferably contains a structural unit derived from the compound represented by the above general formula (B1-1), more preferably contains at least 1 structural unit selected from the group consisting of a structural unit derived from the compound represented by the following formula (B1-1-1), a structural unit derived from the compound represented by the following formula (B1-1-2), and a structural unit derived from the compound represented by the following formula (B1-1-3).

The compound shown as the formula (b1-1-1) is 1, 3-bis [2- (4-aminophenyl) -2-propyl ] benzene,

The compound shown as the formula (b1-1-2) is 1, 3-bis (4-aminophenoxy) benzene,

The compound represented by the formula (b1-1-3) is 1, 3-bis (3-aminophenoxy) benzene.

Among the compounds represented by the formulae (b1-1-1) to (b1-1-3), at least 1 compound selected from the group consisting of the compound represented by the formula (b1-1-1) and the compound represented by the formula (b1-1-2) is preferable, and the compound represented by the formula (b1-1-1) is more preferable.

The proportion of the structural unit (B-1) in the structural unit B is preferably 5 mol% or more, more preferably 15 mol% or more, further preferably 45 mol% or more, and particularly preferably 75 mol% or more. The upper limit of the ratio of the structural unit (B-1) is not particularly limited, i.e., 100 mol%. The structural unit B may contain only the structural unit (B-1).

The proportion of the structural unit (B-1) in the structural unit B is preferably 5 to 100 mol%, more preferably 15 to 100 mol%, still more preferably 45 to 100 mol%, and particularly preferably 75 to 100 mol%.

When the structural unit (B-1) comprises a structural unit derived from a compound represented by the formula (B1-1-1), the proportion of the structural unit derived from a compound represented by the formula (B1-1-1) in the structural unit (B-1) is preferably 50 to 100 mol%, more preferably 75 to 100 mol%, still more preferably 90 to 100 mol%, and particularly preferably 95 to 100 mol%.

The structural unit B may contain a structural unit other than the structural unit (B-1). Such a structural unit is not particularly limited, and preferably contains at least 1 structural unit selected from the group consisting of a structural unit (B-2) derived from a compound represented by the following formula (B-2), a structural unit (B-3) derived from a compound represented by the following formula (B-3), and a structural unit (B-4) derived from a compound represented by the following formula (B-4).

The compound shown as the formula (b-2) is 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane,

The compound shown in the formula (b-3) is 4, 4' -diaminodiphenyl ether,

The compound represented by the formula (b-4) is 1, 4-bis [2- (4-aminophenyl) -2-propyl ] benzene.

When the structural unit B contains at least 1 structural unit selected from the group consisting of the structural units (B-2) to (B-4), it may contain 2 or more of the structural units (B-2) to (B-4), and preferably 1 structural unit of the structural units (B-2) to (B-4). That is, the structural unit B preferably contains the structural unit (B-2), the structural unit (B-3), or the structural unit (B-4).

When the structural unit B contains at least 1 structural unit selected from the group consisting of the structural units (B-2) to (B-4), the total proportion of the structural units (B-2) to (B-4) in the structural unit B is preferably 5 to 95 mol%, more preferably 7 to 85 mol%, still more preferably 10 to 55 mol%, and particularly preferably 12 to 25 mol%.

The structural unit B may contain structural units other than the structural units (B-1) to (B-4). 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, 2 '-bis (trifluoromethyl) benzidine, 4' -diaminodiphenylmethane, 2-bis (4-aminophenyl) hexafluoropropane, 4 '-diaminodiphenylsulfone, 4' -diaminobenzanilide, 3,4 '-diaminodiphenyl ether, 1- (4-aminophenyl) -2, 3-dihydro-1, 3, 3-trimethyl-1H-indene-5-amine, N' -bis (4-aminophenyl) terephthalamide, N-bis (4-aminophenyl) terephthalamide, and the like, Aromatic diamines such as 4, 4' -bis (4-aminophenoxy) biphenyl, 2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 9-bis (4-aminophenyl) fluorene and 1, 4-bis (4-aminophenoxy) benzene; alicyclic diamines such as 1, 3-bis (aminomethyl) cyclohexane and 1, 4-bis (aminomethyl) cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine.

In the present specification, an aromatic diamine refers to a diamine containing 1 or more aromatic rings, an alicyclic diamine refers to a diamine containing 1 or more alicyclic rings and no aromatic rings, and an aliphatic diamine refers to a diamine containing no aromatic rings and no alicyclic rings.

The structural units other than the structural units (B-1) to (B-4) optionally contained in the structural unit B are optionally 1 or 2 or more.

The structural unit B preferably does not contain structural units other than the structural units (B-1) to (B-4).

The polyimide resin of the present invention preferably has a number average molecular weight of 5000 to 100000 from the viewpoint of mechanical strength of the polyimide film to be obtained. The number average molecular weight of the polyimide resin can be determined, for example, from a standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration chromatography.

The polyimide resin of the present invention may have a structure other than a polyimide chain (a structure in which a structural unit a and a structural unit B are imide-bonded). Examples of the structure other than the polyimide chain that can be contained in the polyimide resin include, for example, a structure containing an amide bond.

The polyimide resin of the present invention preferably has a structure mainly composed of a polyimide chain (a structure in which a structural unit a and a structural unit B are imide-bonded). Therefore, the ratio of the polyimide chain in the polyimide resin of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 99% by mass or more.

By using the polyimide resin of the present invention, a film having excellent colorless transparency and a low retardation can be formed, and the film has the following preferable physical property values.

When a film having a thickness of 30 μm is formed, the total light transmittance is preferably 85% or more, more preferably 87% or more, still more preferably 88% or more, and still more preferably 89% or more.

When a film having a thickness of 30 μm is formed, the haze is preferably 2.0% or less, more preferably 1.5% or less, and still more preferably 1.0% or less.

When a film having a thickness of 30 μm is formed, the Yellowness Index (YI) is preferably 4.0 or less, more preferably 3.5 or less, still more preferably 3.0 or less, and still more preferably 2.0 or less.

In the present invention, a polyimide film having a retardation in thickness (Rth) of preferably 90nm or less, more preferably 70nm or less, still more preferably 50nm or less, and still more preferably 30nm or less can be produced. In the present specification, the term "low retardation" means that the retardation by thickness (Rth) is low, and the retardation by thickness (Rth) is preferably within the above range.

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

The film formed by using the polyimide resin of the present invention is also excellent in heat resistance and mechanical properties, and has the following preferable physical property values.

The glass transition temperature (Tg) is preferably 200 ℃ or higher, more preferably 230 ℃ or higher, and still more preferably 250 ℃ or higher.

The tensile modulus is preferably 2.5GPa or more, more preferably 3.0GPa or more, and still more preferably 3.5GPa or more.

The tensile strength is preferably 70MPa or more, more preferably 90MPa or more, and still more preferably 100MPa or more.

The tensile modulus of elasticity and tensile strength are in accordance with jis k 7127: 1999 measured value.

[ method for producing polyimide resin ]

The polyimide resin of the present invention can be produced by reacting a tetracarboxylic acid component containing at least 1 selected from the group consisting of a compound that provides the structural unit (a-1) and a compound that provides the structural unit (a-2) with a diamine component containing a compound that provides the structural unit (B-1).

Examples of the compound providing the structural unit (A-1) include, but are not limited to, compounds represented by the formula (a-1), and derivatives thereof may be included within the range providing the same structural unit. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by the formula (a-1) and an alkyl ester of the tetracarboxylic acid. As the compound providing the structural unit (A-1), a compound represented by the formula (a-1) (i.e., dianhydride) is preferred.

Similarly, examples of the compound providing the structural unit (A-2) include, but are not limited to, compounds represented by the formula (a-2), and derivatives thereof may be included within the range providing the same structural unit. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by the formula (a-2) and an alkyl ester of the tetracarboxylic acid. As the compound providing the structural unit (A-2), a compound represented by the formula (a-2) (i.e., dianhydride) is preferred.

The tetracarboxylic acid component preferably contains 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol% or more of the compound that provides the structural unit (A-1) and the compound that provides the structural unit (A-2) in total. The upper limit of the total content of the compound that provides the structural unit (A-1) and the compound that provides the structural unit (A-2) is not particularly limited, i.e., 100 mol%. The tetracarboxylic acid component may contain only the compound which provides the structural unit (A-1) and the compound which provides the structural unit (A-2).

When the tetracarboxylic acid component contains a compound that can provide the structural unit (A-1) or a compound that can provide the structural unit (A-2), the tetracarboxylic acid component preferably contains 45 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more of a compound that can provide the structural unit (A-1) or a compound that can provide the structural unit (A-2). The upper limit of the content of the compound that provides the structural unit (A-1) or the compound that provides the structural unit (A-2) is not limited, i.e., 100 mol%. The tetracarboxylic acid component may contain only the compound which provides the structural unit (A-1) or the compound which provides the structural unit (A-2), and preferably contains only the compound which provides the structural unit (A-1).

The tetracarboxylic acid component may contain a compound that provides the above-mentioned structural unit (A-3) within a range that does not impair the physical properties of the low retardation amount.

Examples of the compound providing the structural unit (A-3) include compounds represented by the formula (a-3), but are not limited thereto, and derivatives thereof may be included within the range providing the same structural unit. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by the formula (a-3) and an alkyl ester of the tetracarboxylic acid. As the compound providing the structural unit (A-3), a compound represented by the formula (a-3) (i.e., dianhydride) is preferable.

When the tetracarboxylic acid component contains a compound that can provide the structural unit (A-3), the tetracarboxylic acid component preferably contains 55 mol% or less, more preferably contains 30 mol% or less of the compound that can provide the structural unit (A-3). When the tetracarboxylic acid component contains a compound that can provide the structural unit (A-3), it is preferable that the tetracarboxylic acid component contains only a compound that can provide the structural unit (A-1) and a compound that can provide the structural unit (A-3).

The tetracarboxylic acid component may contain compounds other than the compound providing the structural unit (A-1), the compound providing the structural unit (A-2), and the compound providing the structural unit (A-3), and examples of the compounds include the aromatic tetracarboxylic acid dianhydride, the alicyclic tetracarboxylic acid dianhydride, and the aliphatic tetracarboxylic acid dianhydride described above, and derivatives thereof (e.g., tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.).

The tetracarboxylic acid component may optionally contain 1 or 2 or more compounds other than the compounds providing the structural units (A-1) to (A-3).

Examples of the compound that can provide the structural unit (B-1) include, but are not limited to, compounds represented by the general formula (B1-1) and compounds represented by the general formula (B2-1), and derivatives thereof may be provided as long as the same structural unit is provided. Examples of the derivative include a diisocyanate corresponding to a compound represented by the general formula (b1-1) and a diisocyanate corresponding to a diamine represented by the general formula (b 2-1). As the compound providing the structural unit (B-1), at least 1 compound (i.e., diamine) selected from the group consisting of the compound represented by the general formula (B1-1) and the compound represented by the general formula (B2-1) is preferable.

The compound that provides the structural unit (B-1) preferably contains a compound represented by the general formula (B1-1), more preferably contains at least 1 compound selected from the group consisting of a compound represented by the formula (B1-1-1), a compound represented by the formula (B1-1-2), and a compound represented by the formula (B1-1-3), further preferably contains at least 1 compound selected from the group consisting of a compound represented by the formula (B1-1-1) and a compound represented by the formula (B1-1-2), and particularly preferably contains a compound represented by the formula (B1-1-1).

The diamine component preferably contains 5 mol% or more, more preferably 15 mol% or more, still more preferably 45 mol% or more, and particularly preferably 75 mol% or more of the compound that provides the structural unit (B-1). The upper limit of the content of the compound providing the structural unit (B-1) is not particularly limited, i.e., 100 mol%. The diamine component may contain only a compound that provides the structural unit (B-1).

When the compound that provides the structural unit (B-1) includes a compound represented by the formula (B1-1-1), the proportion of the compound represented by the formula (B1-1-1) in the compound that provides the structural unit (B-1) is preferably 50 to 100 mol%, more preferably 75 to 100 mol%, still more preferably 90 to 100 mol%, and particularly preferably 95 to 100 mol%.

The diamine component may contain at least 1 compound selected from the group consisting of a compound that provides the structural unit (B-2), a compound that provides the structural unit (B-3), and a compound that provides the structural unit (B-4) within a range that does not impair the colorless transparency and the physical properties of the low retardation.

The compounds which provide the structural units (B-2) to (B-4) may be represented by the formulae (B-2) to (B-4), respectively, but the compounds are not limited thereto, and derivatives thereof may be provided as long as the same structural units are provided. Examples of the derivative include diisocyanates corresponding to diamines represented by the formulae (b-2) to (b-4). As the compounds providing the structural units (B-2) to (B-4), compounds represented by the formulae (B-2) to (B-4) (i.e., diamines) are preferred.

When the diamine component contains a compound that provides at least 1 structural unit selected from the group consisting of the structural units (B-2) to (B-4), it may contain a compound that provides 2 or more structural units selected from the structural units (B-2) to (B-4), and preferably contains 1 structural unit selected from the structural units (B-2) to (B-4). That is, the structural unit B preferably contains a compound which provides the structural unit (B-2), a compound which provides the structural unit (B-3), or a compound which provides the structural unit (B-4).

When the diamine component contains a compound that provides at least 1 structural unit selected from the group consisting of the structural units (B-2) to (B-4), the diamine component preferably contains 5 to 95 mol%, more preferably contains 7 to 85 mol%, even more preferably contains 10 to 55 mol%, and particularly preferably contains 12 to 25 mol% of the compound.

The diamine component may contain compounds other than the compounds providing the structural units (B-1) to (B-4), and examples of the compounds include the above-mentioned aromatic diamine, alicyclic diamine, and aliphatic diamine, and derivatives thereof (e.g., diisocyanate).

The diamine component optionally contains 1 or 2 or more compounds other than the compounds providing the structural units (B-1) to (B-4).

In the present invention, the amount ratio of the tetracarboxylic acid component and the diamine component used for producing the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component to 1 mol of the tetracarboxylic acid component.

In the present invention, in addition to the tetracarboxylic acid component and the diamine component described above, an end-capping agent may be used in the production of the polyimide resin. As the end-capping agent, monoamines or dicarboxylic acids are preferred. The amount of the end-capping agent to be introduced is preferably 0.0001 to 0.1 mol, and particularly preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. As the monoamine-type blocking agent, 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. As the dicarboxylic acid-based end capping agent, dicarboxylic acids are preferred, and a part thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2, 3-benzophenonedicarboxylic acid, 3, 4-benzophenonedicarboxylic 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.

The method for reacting the tetracarboxylic acid component with the diamine component is not particularly limited, and a known method can be used.

Specific reaction methods include: (1) a method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, stirred at room temperature to 80 ℃ for 0.5 to 30 hours, and then heated to effect imidization; (2) a method in which a diamine component and a reaction solvent are put into a reactor and dissolved, a tetracarboxylic acid component is put into the reactor, and the mixture is stirred at room temperature to 80 ℃ for 0.5 to 30 hours, if necessary, and then heated to carry out imidization; (3) a method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, and the temperature is immediately raised to perform an imidization reaction.

The reaction solvent used for producing the polyimide resin may be any solvent which can dissolve the polyimide produced without inhibiting the imidization reaction. Examples thereof include aprotic solvents, phenol solvents, ether solvents, carbonate solvents and the like.

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

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

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, ethyl methyl carbonate, ethylene carbonate, and propylene carbonate.

Among the above reaction solvents, an amide solvent or a lactone solvent is preferable. The above-mentioned reaction solvents may be used singly or in combination of two or more.

In the imidization reaction, it is preferable to use a dean-Stark apparatus or the like, and to carry out the reaction while removing the water produced during the production. By performing such an operation, the degree of polymerization and the imidization ratio can be further increased.

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

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

Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexanoic 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 singly or in combination of two or more.

Among the above, from the viewpoint of handling properties, it is preferable to use a basic catalyst, more preferable to use an organic basic catalyst, still more preferable to use 1 or more selected from triethylamine and triethylenediamine, and particularly preferable to use triethylamine or to use triethylamine and triethylenediamine in combination.

The temperature of the imidization reaction is preferably 120 to 250 ℃ and more preferably 160 to 200 ℃ from the viewpoint of suppressing the reactivity, gelation, and the like. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the product water.

[ polyimide varnish ]

The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention comprises the polyimide resin of the present invention and an organic solvent, and the polyimide resin is dissolved in the organic solvent.

The organic solvent is not particularly limited as long as the polyimide resin is dissolved therein, and as the reaction solvent used for producing the polyimide resin, it is preferable to use a mixture of 2 or more of the above compounds alone.

The polyimide varnish of the present invention may be a polyimide solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or a polyimide solution in which a diluting solvent is further added to the polyimide solution.

The polyimide varnish of the present invention may be prepared by dissolving the polyimide resin of the present invention in a low boiling point solvent having a boiling point of 130 ℃ or lower. By using the low boiling point solvent as the organic solvent, the heating temperature in producing a polyimide film to be described later can be reduced. Examples of the low boiling point solvent include carbon tetrachloride, methylene chloride, chloroform, 1, 2-dichloroethane, tetrahydrofuran, and acetone, and among them, methylene chloride is preferable.

The polyimide resin of the present invention has solvent solubility, and therefore can be used as a varnish having a high concentration stably at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass, more preferably 10 to 30% by mass of the polyimide resin of the present invention. The viscosity of the polyimide varnish is preferably 1 to 200 pas, more preferably 5 to 150 pas. The viscosity of the polyimide varnish was measured at 25 ℃ using an E-type viscometer.

The polyimide varnish of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoaming agents, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitizers, as long as the required properties of the polyimide film are not impaired.

The method for producing the polyimide 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 the polyimide resin of the present invention. Therefore, the polyimide film of the present invention is excellent in colorless transparency and further has a low retardation. The polyimide film of the present invention has the preferred physical property values as described above.

The method for producing the polyimide film of the present invention is not particularly limited, and a known method can be used. For example, the polyimide varnish of the present invention is applied to a smooth support such as a glass plate, a metal plate or a plastic, or formed into a film, and then the organic solvent such as a reaction solvent or a diluting solvent contained in the varnish is removed by heating. If necessary, a release agent may be applied in advance to the surface of the support.

As a method for removing the organic solvent contained in the varnish by heating, the following method is preferable. That is, it is preferable to produce a polyimide film by evaporating an organic solvent at a temperature of 120 ℃ or lower to form a self-supporting film, then peeling the self-supporting film from a support, fixing the end of the self-supporting film, and drying the film at a temperature of the boiling point of the organic solvent used or higher. Further, it is preferable to perform drying under a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced pressure, normal pressure or increased pressure. The heating temperature for producing the polyimide film by drying the self-supporting film is not particularly limited, but is preferably 200 to 400 ℃.

When the organic solvent contained in the polyimide varnish of the present invention is a low boiling point solvent having a boiling point of 130 ℃ or less, the heating temperature of the self-supporting film is preferably 100 to 180 ℃. Further, it is preferable that the polyimide film obtained by removing the low boiling point solvent is further subjected to annealing treatment at a temperature equal to or higher than the glass transition temperature.

The polyimide film of the present invention can also be produced using a polyamic acid varnish in which a polyamic acid is dissolved in an organic solvent.

The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, and is a product of addition polymerization of a tetracarboxylic acid component containing at least 1 selected from the group consisting of the compound providing the structural unit (a-1) and the compound providing the structural unit (a-2), and a diamine component containing the compound providing the structural unit (B-1). The polyimide resin of the present invention can be obtained as a final product by imidizing (dehydrating ring closure) the polyamic acid.

As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.

In the present invention, the polyamic acid varnish may be a polyamic acid solution itself obtained by addition polymerization of a tetracarboxylic acid component containing at least 1 selected from the group consisting of a compound that provides the structural unit (a-1) and a compound that provides the structural unit (a-2) and a diamine component containing a compound that provides the structural unit (B-1) in a reaction solvent, or a polyamic acid solution obtained by further adding a diluting solvent to the polyamic acid solution.

The method for producing the polyimide film using the polyamic acid varnish is not particularly limited, and a known method can be used. For example, a polyimide film can be produced as follows: the polyamic acid varnish is applied to a smooth support such as a glass plate, a metal plate, or a plastic or formed into a film, an organic solvent such as a reaction solvent or a diluting solvent contained in the varnish is removed by heating to obtain a polyamic acid film, and the polyamic acid in the polyamic acid film is imidized by heating to produce the polyamic acid film.

The heating temperature for drying the polyamic acid varnish to obtain a polyamic acid film is preferably 50 to 120 ℃. The heating temperature for imidizing the polyamic acid by heating is preferably 200 to 400 ℃.

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 suitably selected depending on the application, and is preferably 1 to 250. mu.m, more preferably 5 to 100. mu.m, and still more preferably 10 to 80 μm. The film has a thickness of 1 to 250 μm and can be practically used as a self-supporting film.

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

Examples

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

The solid content concentration of the varnish and the physical properties of the film obtained in the examples and comparative examples were measured by the methods shown below.

(1) Concentration of solid component

The solid content concentration of the varnish was measured by heating a sample at 280 ℃ for 120 minutes in a small electric furnace "MMF-1" manufactured by AS ONE CORPORATION, and calculating the mass difference between the sample before and after heating.

(2) Thickness of film

The film thickness was measured using a micrometer manufactured by Sanfeng corporation.

(3) Total light transmittance, Yellowness Index (YI), haze

The total light transmittance, YI and haze were measured by using a color/haze simultaneous measuring instrument "COH 400" manufactured by Nippon Denshoku industries Co., Ltd. The total light transmittance and YI were measured according to JIS K7361-1: 1997, haze was measured according to JIS K7136: 2000

(4) Thickness retardation (Rth)

The thickness retardation (Rth) was measured using an ellipsometer "M-220" manufactured by Nippon spectral Co., Ltd. The value of thickness retardation at a measurement wavelength of 550nm was measured. In addition, regarding Rth, when nx is the maximum in-plane refractive index, ny is the minimum in-plane refractive index, nz is the refractive index in the thickness direction, and d is the thickness of the film, it is represented by the following formula.

Rth＝[{(nx+ny)/2}-nz]×d

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

< tetracarboxylic acid component >

HPMDA: 1,2,4, 5-Cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi gas chemical Co., Ltd.; Compound represented by formula (a-1))

CpODA: norbornane-2-spiro- α -cyclopentanone- α' -spiro-2 "-norbornane-5, 5", 6,6 "-tetracarboxylic dianhydride (JXTG ENERGY, manufactured by JXTG ENERGY; compound represented by the formula (a-3))

< diamine component >

BisAM: 1, 3-bis [2- (4-aminophenyl) -2-propyl ] benzene (Compound represented by the formula (b1-1-1, manufactured by MITSUI FINE CHEMICALS, INC.))

TPER: 1, 3-bis (4-aminophenoxy) benzene (a compound represented by the formula (b1-1-2) manufactured by Harris Hill Seiki Kaisha)

APBN: 1, 3-bis (3-aminophenoxy) benzene (a compound represented by the formula (b1-1-3) manufactured by Mitsui chemical Co., Ltd.)

TPEQ: 1, 4-bis (4-aminophenoxy) benzene (manufactured by Harris Hill Seikagana Kogyo Co., Ltd.)

3, 5-DABA: 3, 5-diaminobenzoic acid (made by Nippon pure drug Co., Ltd.)

BAPA: 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (produced by Harris Seikagana Kogyo Co., Ltd.)

ODA: 4, 4' -diaminodiphenyl ether (a compound represented by the formula (b-3) manufactured by Harmony mountain refining industries, Ltd.)

BAPP: 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (a compound represented by the formula (b-2) manufactured by Harris Hill Seikagaku Kogyo Co., Ltd.)

3, 4' -DPE: 3, 4' -diaminodiphenyl ether (manufactured by Harris mountain refinement industries Co., Ltd.)

BisAP: 1, 4-bis [2- (4-aminophenyl) -2-propyl ] benzene (Compound represented by the formula (b-4) manufactured by MITSUI FINE CHEMICALS, INC.)

Details of the solvents and catalysts used in examples and comparative examples are as follows.

Gamma-butyrolactone (manufactured by Mitsubishi chemical corporation)

N, N-Dimethylacetamide (manufactured by Mitsubishi gas chemical Co., Ltd.)

Triethylenediamine (manufactured by Tokyo Kasei Co., Ltd.)

Triethylamine (manufactured by Kanto chemical Co., Ltd.)

< example 1>

As a reaction apparatus, a 0.3L 5-neck glass round-bottomed flask equipped with a stainless steel semilunar stirring blade, a nitrogen gas inlet tube, a cooling tube, a dean-Stark apparatus, a thermometer, and a glass end cap was used, and BisAM25.920g (0.075 mol), gamma-butyrolactone (Mitsubishi chemical Co., Ltd.) 35.0g, and triethylenediamine as a catalyst 0.048g and triethylamine 3.80g were charged into the round-bottomed flask, and the temperature was raised to 70 ℃ under nitrogen atmosphere with stirring at 150rpm to obtain a solution. To this solution, 16.830g (0.075 mol) of HPMDA and 17.1g of gamma-butyrolactone were added together, and the mixture was heated with a mantle heater to raise the temperature in the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 5.5 hours. 67.71g of N, N-dimethylacetamide was added thereto, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 25 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 30 μm. The evaluation results of the polyimide film are shown in table 1.

< example 2>

Using the same reaction apparatus as in example 1, APBN24.899g (0.085 mol), gamma-butyrolactone 40.0g, and triethylamine 4.30g as a catalyst were charged in a round-bottomed flask, and the temperature was raised to 70 ℃ while stirring at 150rpm under a nitrogen atmosphere to obtain a solution. To this solution, 19.074g (0.085 mol) of HPMDA19 and 13.7g of gamma-butyrolactone were added together, and then the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 3.3 hours. 41.6g of N, N-dimethylacetamide was added thereto, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 30 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 47 μm. The evaluation results of the polyimide film are shown in table 1.

< example 3>

Using the same reaction apparatus as in example 1, tper24.337g (0.083 moles), γ -butyrolactone 45.1g, and triethylamine 2.11g as a catalyst were charged into a round-bottomed flask, and the temperature was raised to 70 ℃ while stirring at 150rpm under a nitrogen atmosphere to obtain a solution. To the solution were added 18.701g (0.083 mol) of HPMDA18 and 19.4g of N, N-dimethylacetamide together, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 2.7 hours. After 64.5g of N, N-dimethylacetamide was added thereto, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 24 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 31 μm. The evaluation results of the polyimide film are shown in table 1.

< comparative example 1>

Using the same reaction apparatus as in example 1, TPEQ23.370g (0.080 mol), γ -butyrolactone 40.4g, and triethylamine 0.41g as a catalyst were charged into a round-bottomed flask, and the temperature was raised to 80 ℃ under a nitrogen atmosphere while stirring at 150rpm, to obtain a solution. To this solution were added HPMDA17.934g (0.080 mol) and gamma-butyrolactone 10.1g, respectively, and the mixture was heated by a mantle heater to raise the temperature in the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 2.5 hours. After adding 103.3g of N, N-dimethylacetamide, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 18 μm. The evaluation results of the polyimide film are shown in table 1.

< comparative example 2>

Using the same reaction apparatus as in example 1,3, 5-DABA28.559g (0.188 mol), gamma-butyrolactone 132.1g, and triethylamine 0.95g as a catalyst were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 42.132g (0.188 mol) of HPMDA and 33.03g of gamma-butyrolactone, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 5.0 hours. 90.86g of gamma-butyrolactone was added, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 29 μm. The evaluation results of the polyimide film are shown in table 1.

< comparative example 3>

Using the same reaction apparatus as in example 1, in a round-bottomed flask, 42.278g (0.115 mol) of BAPA, 81.8g of gamma-butyrolactone and 0.58g of triethylamine as a catalyst were added, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To this solution were added 25.877g (0.115 mol) of HPMDA and 20.4g of gamma-butyrolactone, respectively, and the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 5.0 hours. 153.8g of gamma-butyrolactone was added, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame, and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 26 μm. The evaluation results of the polyimide film are shown in table 1.

< comparative example 4>

Using the same reaction apparatus as in example 1, 20.024g (0.100 mol) of ODA, 45.0g of gamma-butyrolactone and 1.52g of triethylamine as a catalyst were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 22.417g (0.100 mol) of HPMDA and 18.7g of gamma-butyrolactone, respectively, and the mixture was heated by a mantle heater to raise the temperature of the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 4.0 hours. After 91.7g of N, N-dimethylacetamide was added thereto, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 40 μm. The evaluation results of the polyimide film are shown in table 1.

< comparative example 5>

Using the same reaction apparatus as in example 1, 43.745g (0.107 mol) of BAPP, 81.4g of gamma-butyrolactone and 0.54g of triethylamine as a catalyst were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 23.887g (0.107 mol) of HPMDA and 20.3g of gamma-butyrolactone (manufactured by Mitsubishi chemical corporation) in combination, and the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 4.0 hours. 154.2g of gamma-butyrolactone (manufactured by Mitsubishi chemical corporation) was added, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 33 μm. The evaluation results of the polyimide film are shown in table 1.

< comparative example 6>

Using the same reaction apparatus as in example 1, 20.024g (0.100 mol) of 3, 4' -DPE, 45.0g of gamma-butyrolactone, 0.065g of triethylenediamine as a catalyst, and 1.52g of triethylamine were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 22.417g (0.100 mol) of HPMDA and 18.7g of gamma-butyrolactone, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 4.0 hours. After 91.7g of N, N-dimethylacetamide was added thereto, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 25 μm. The evaluation results of the polyimide film are shown in table 1.

[ tables 1-1]

Table 1(1/4)

< example 4>

Using the same reaction apparatus as in example 1, 14.417g (0.072 mol) of ODA, 6.201g (0.018 mol) of BisAM, 40.0g of gamma-butyrolactone, 0.050g of triethylenediamine as a catalyst, and 4.55g of triethylamine were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 20.175g (0.090 mol) of HPMDA and 10.0g of gamma-butyrolactone, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 0.7 hour. After 38.0g of N, N-dimethylacetamide was added thereto, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 30 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 42 μm. The evaluation results of the polyimide film are shown in table 1.

< example 5>

Using the same reaction apparatus as in example 1, 10.012g (0.050 mol) of ODA, 48.7g (0.050 mol) of BisAM 17.225g, and 48.7g of gamma-butyrolactone, as well as 0.056g of triethylenediamine and 5.06g of triethylamine as catalysts were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 22.417g (0.10 mol) of HPMDA and 12.2g of gamma-butyrolactone, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 0.6 hour. 77.8g of N, N-dimethylacetamide was added thereto, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 25 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 34 μm. The evaluation results of the polyimide film are shown in table 1.

< example 6>

As a reaction apparatus, a 3.0L apparatus similar to that used in example 1 was used, and 23.228g (0.116 mol) of ODA, 159.848g (0.464 mol) of BisAM, 307.0g of gamma-butyrolactone, 0.325g of triethylenediamine as a catalyst, and 29.345g of triethylamine were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 130.019g (0.580 mol) of HPMDA and 76.8g of gamma-butyrolactone, respectively, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 2.0 hours. After adding 300.0g of N, N-dimethylacetamide, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 30 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the temperature was gradually raised and held at the maximum temperature of 140 ℃ for about 2 minutes to volatilize the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 32 μm. The evaluation results of the polyimide film are shown in table 1.

[ tables 1-2]

Table 1(2/4)

< example 7>

Using the same reaction apparatus as in example 1, 27.259g (0.066 mol) of BAPP, 5.719g (0.017 mol) of BisAM, 50.6g of gamma-butyrolactone, 0.047g of triethylenediamine as a catalyst, and 4.20g of triethylamine were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 18.606g (0.083 mol) of HPMDA and 12.6g of gamma-butyrolactone, and the mixture was heated with a mantle heater to raise the temperature of the reaction system to 200 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 200 ℃ for 0.5 hour. 83.0g of N, N-dimethylacetamide was added thereto, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 25 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 47 μm. The evaluation results of the polyimide film are shown in table 1.

< example 8>

Using the same reaction apparatus as in example 1, 16.421g (0.040 mol) of BAPP, 13.780g (0.040 mol) of BisAM, 40.0g of gamma-butyrolactone, 0.044g of triethylenediamine as a catalyst, and 4.05g of triethylamine were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To this solution were added HPMDA17.934g (0.080 mol) and γ -butyrolactone 18.8g, respectively, and then the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 2.2 hours. After adding 122.2g of N, N-dimethylacetamide, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 30 μm. The evaluation results of the polyimide film are shown in table 1.

< example 9>

Using the same reaction apparatus as in example 1, in a round-bottomed flask, 6.568g (0.016 mol) of BAPP, 22.048g (0.064 mol) of BisAM, 30.0g of gamma-butyrolactone, 0.044g of triethylenediamine as a catalyst, and 4.05g of triethylamine were added, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃ to obtain a solution. To the solution were added 17.934g (0.080 mol) of HPMDA and 16.6g of gamma-butyrolactone, respectively, and the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 1.4 hours. After 84.4g of N, N-dimethylacetamide was added thereto, the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 25 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 35 μm. The evaluation results of the polyimide film are shown in table 1.

[ tables 1 to 3]

Table 1(3/4)

< example 10>

Using the same reaction apparatus as in example 1, BisAM 27.560g (0.080 mol), gamma-butyrolactone 30.8g, and triethylenediamine 0.022g and triethylamine 2.02g as catalysts were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere to raise the temperature to 70 ℃ to obtain a solution. To the solution were added 8.967g (0.040 mol) of HPMDA, 15.375g (0.040 mol) of CpODA and 32.9g of gamma-butyrolactone, and the mixture was heated with a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 2.0 hours. 88.0g of N, N-dimethylacetamide was added thereto, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 25 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 38 μm. The evaluation results of the polyimide film are shown in table 1.

< example 11>

Using the same reaction apparatus as in example 1, 13.780g (0.040 mol) of BisAP, 13.780g (0.040 mol) of BisAM, 40.0g of γ -butyrolactone, and 0.044g of triethyldiamine and 4.05g of triethylamine as catalysts were added to a round-bottomed flask, and the mixture was stirred at 150rpm under a nitrogen atmosphere and heated to 70 ℃. To the solution were added 17.934g (0.080 mol) of HPMDA and 15.6g of gamma-butyrolactone, respectively, and the mixture was heated by a mantle heater to raise the temperature in the reaction system to 190 ℃ over about 20 minutes. The distilled components were collected, and the temperature in the reaction system was maintained at 190 ℃ for 3.5 hours. 114.8g of N, N-dimethylacetamide was added thereto, and the mixture was stirred at about 100 ℃ for about 1 hour to obtain a uniform polyimide varnish having a solid content of 20 mass%.

Then, the obtained polyimide varnish was coated on a PET substrate, and the substrate was kept at 100 ℃ for 20 minutes to evaporate the solvent, thereby obtaining a colorless transparent primary dried film having self-supporting properties. The film was fixed on a stainless steel frame and dried at 210 ℃ for 20 minutes in an air atmosphere to remove the solvent, thereby obtaining a film having a thickness of 35 μm. The evaluation results of the polyimide film are shown in table 1.

[ tables 1 to 4]

Table 1(4/4)

As shown in Table 1, the polyimide films of examples 1 to 11 produced using a specific tetracarboxylic acid component and a specific diamine component were excellent in colorless transparency and further low in retardation.

On the other hand, the polyimide films of comparative examples 1 to 6, which did not use a diamine providing the structural unit (B-1) as a diamine component, had a larger retardation value (Rth) than the polyimide films of examples 1 to 3.

The polyimide films of examples 4 to 6 using the BisAM and ODA in combination as diamine acid components had a significantly reduced retardation value (Rth) as compared with the polyimide film of comparative example 4 produced using ODA alone.

The polyimide films of examples 7 to 9 using BisAM and BAPP in combination as diamine acid components had a significantly reduced retardation value (Rth) as compared with the polyimide film of comparative example 5 produced using BAPP alone.

Industrial applicability

The polyimide film of the present invention can be suitably used as a film for various members such as color filters, flexible displays, semiconductor components, and optical members. The polyimide film of the present invention can be particularly suitably used as a substrate for an image display device such as a liquid crystal display, an OLED display, or the like.