Polyimide resin precursor and polyimide resin

Abstract

A polyimide resin precursor containing a repeating unit represented by general formula (1), or containing a repeating unit represented by general formula (1) and a repeating unit represented by general formula (2), the amount of the repeating units being less than the amount of the repeating units per all of the repeating units of the polyimide resin precursor, or the amount of the repeating units represented by general formula (1) and the repeating units represented by general formula (2). The total of the repeating units represented by general formula (1) and the repeating units represented by general formula (2) is 70-100 mol%, and the ratio of the repeating units represented by general formula (1) to the total of the repeating units represented by general formula (1) and the repeating units represented by general formula (2) is 30-100 mol%. The polyimide resin precursor makes it possible to obtain a polyimide resin having excellent heat resistance, a low linear expansion coefficient, and excellent elongation and mechanical strength. # imgabs0 #

Description

Technical Field

[0001] The invention relates to a polyimide resin precursor, a polyimide resin and a polyimide film. Background Art

[0002] Various uses of polyimide resins in the fields of electrical and electronic components have been studied. In particular, in recent years, the use of transparent flexible substrates that utilize characteristics such as lightness and flexibility has been studied instead of glass substrates that have been used in the field of display materials. In order to use polyimide resins as transparent flexible substrates, heat resistance and mechanical strength are required in addition to transparency. In order to meet these conditions, attempts have been made to synthesize semi-aromatic polyimides by studying tetracarboxylic acids and diamines as raw materials.

[0003] For example, Patent Document 1 discloses a method for producing a polyimide by reacting 1,2,3,4-cyclobutanetetracarboxylic dianhydride with bis(4-aminophenyl)terephthalate to obtain a polyamic acid, followed by imidization, for the purpose of obtaining a colorless, transparent, heat-resistant, low linear expansion coefficient, and excellent toughness polyimide.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-077184 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] Recently, polyimide is also used in the manufacture of TFT substrates, but when the device type of TFT is LTPS (low temperature polysilicon TFT), the process temperature exceeds 400°C. Due to the difference in linear expansion coefficient with the support body, the support body is warped, and the difference in linear thermal expansion coefficient with the inorganic layer constituting the device is different. There is a concern that the bonding surface may peel off and the product may deform due to the above-mentioned thermal history. For the above reasons, for polyimide used as a substrate, it is necessary to reduce the linear expansion coefficient on the basis of a high glass transition temperature. In addition, for polyimide used for such purposes, elongation and mechanical strength are also required.

[0009] As described above, there is a demand for polyimide having higher heat resistance and lower linear expansion coefficient than before, and further having both elongation and mechanical strength.

[0010] The present invention is completed in view of such a situation, and the subject of the present invention is to provide a polyimide resin precursor that can obtain a polyimide resin having excellent heat resistance, a low linear expansion coefficient, and thus excellent elongation and mechanical strength, as well as a polyimide resin and a polyimide film having excellent heat resistance, a low linear expansion coefficient, and thus excellent elongation and mechanical strength.

[0011] Solutions for solving problems

[0012] The present inventors have found that a polyimide resin precursor having a specific structural unit and a polyimide resin obtained using the precursor can solve the above-mentioned problems, and have completed the invention.

[0013] That is, the present invention relates to the following [1] to [9].

[0014] [1] A polyimide resin precursor comprising a repeating unit represented by the following general formula (1), or comprising a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), wherein the total amount of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin precursor, and the ratio of the repeating unit represented by the general formula (1) to the total amount of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 30 to 100 mol%.

[0015]

[0016] (In formula (1) and formula (2), X 1 and X 2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0017] [2] The polyimide resin precursor according to [1] above, wherein the ratio of the repeating unit represented by the general formula (1) to the total of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 50 to 100 mol%.

[0018] [3] A varnish comprising the polyimide resin precursor according to [1] or [2] and an organic solvent.

[0019] [4] A polyimide film obtained by applying the varnish described in [3] above onto a support and heating the coated support.

[0020] [5] A polyimide resin comprising a repeating unit represented by the following general formula (3), or comprising a repeating unit represented by the following general formula (3) and a repeating unit represented by the following general formula (4), wherein the total amount of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin, and the ratio of the repeating unit represented by the general formula (3) to the total amount of the repeating unit represented by the general formula (3) and the repeating unit represented by the following general formula (4) is 30 to 100 mol%.

[0021]

[0022] (In formula (3) and formula (4), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0023] [6] The polyimide resin according to [5] above, wherein the ratio of the repeating unit represented by the general formula (3) to the total of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 50 to 100 mol%.

[0024] [7] A polyimide film comprising the polyimide resin described in [5] or [6] above.

[0025] [8] The polyimide film according to the above [4] or [7], wherein the glass transition temperature is above 430°C, the tensile elongation of the polyimide film at 23°C and 50% RH when the thickness of the polyimide film is 10 μm is above 15%, and the total light transmittance of the polyimide film when the thickness of the polyimide film is 10 μm is above 80%.

[0026] [9] The polyimide film according to [4], [7] or [8] above, wherein the thickness of the polyimide film is 1 μm or more and 20 μm or less.

[0027] Effects of the Invention

[0028] According to the present invention, a polyimide resin precursor can be provided which can obtain a polyimide resin having excellent heat resistance, low linear expansion coefficient, and thus excellent elongation and mechanical strength, as well as a polyimide resin and a polyimide film having excellent heat resistance, low linear expansion coefficient, and thus excellent elongation and mechanical strength. The polyimide resin of the present invention has the above-mentioned properties, and is therefore useful as a raw material for a transparent flexible substrate, particularly a LTPS-TFT substrate. DETAILED DESCRIPTION

[0029] [Polyimide resin precursor]

[0030] The polyimide resin precursor of the present invention comprises a repeating unit represented by the following general formula (1), or comprises a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), wherein the total amount of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin precursor, and the ratio of the repeating unit represented by the general formula (1) to the total amount of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 30 to 100 mol%.

[0031]

[0032] (In formula (1) and formula (2), X 1 and X 2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0033] By using the polyimide resin precursor of the present invention, a polyimide resin having excellent heat resistance, low linear expansion coefficient, and excellent elongation and mechanical strength can be obtained. In addition, the reason why the obtained polyimide resin and polyimide film have excellent heat resistance, low linear expansion coefficient, and excellent elongation and mechanical strength is still uncertain, but it is believed to be as follows.

[0034] It is believed that among aromatic diamines, specific diamines having an ester skeleton as a bonding group of an aromatic ring have high rigidity, and a copolymer formed from a component derived from a specific aromatic tetracarboxylic dianhydride and the above-mentioned diamine component having a specific ester skeleton can achieve both a low linear expansion coefficient and high heat resistance required for TFT substrates, etc.

[0035] On the other hand, when rigidity becomes too high, there is a tendency that elongation and mechanical strength reduce. In addition, the higher the molecular weight of the polyimide is, the more the tendency that elongation and mechanical strength increase. It is believed that the polyimide of the present invention is copolymerized with a specific acid dianhydride with a soft ether skeleton and a specific acid dianhydride with a rigid skeleton in an appropriate ratio, and then copolymerized with an aromatic diamine with a specific ester skeleton high in nucleophilicity in order to increase the molecular weight, thereby except taking into account above-mentioned low linear expansion coefficient, high heat resistance, also has excellent elongation, mechanical strength.

[0036] In addition, the "repeating unit" in a polyimide resin precursor means an amic acid unit, an amic acid ester unit, or an amic acid silyl ester unit containing one structural unit derived from tetracarboxylic dianhydride and one structural unit derived from diamine.

[0037] In the above formula (1), X 1 and X 2 Each independently represents at least one selected from a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkylsilyl group having 3 to 9 carbon atoms, preferably at least one selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom.

[0038] In the above formula (1), R 1 , R 2 , R 3 Each independently represents at least one selected from the group consisting of a methyl group, a fluoro group and a trifluoromethyl group, and is preferably a methyl group.

[0039] In the above formula (1), h, i, and j are each independently an integer of 0 to 4, and preferably 0.

[0040] In the above formula (2), X 1 and X 2 Each independently represents at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and an alkylsilyl group having 3 to 9 carbon atoms, preferably at least one selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom.

[0041] In the above formula (2), R 1 , R 2 , R 3 Each independently represents at least one selected from the group consisting of a methyl group, a fluoro group and a trifluoromethyl group, and is preferably a methyl group.

[0042] In the above formula (2), h, i, and j are each independently an integer of 0 to 4, and preferably 0.

[0043] As described above, the polyimide resin precursor contains the repeating unit represented by the above general formula (1) and may contain the repeating unit represented by the above general formula (2).

[0044] The ratio of the repeating unit represented by the general formula (1) to the total of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 30 to 100 mol%, preferably 40 to 100 mol%, more preferably 50 to 100 mol%, further preferably 60 to 100 mol%, further preferably 70 to 100 mol%, further preferably 80 to 100 mol%, further preferably 90 to 100 mol%, and may be 100 mol%. In addition, from the viewpoint of heat resistance and strength, it is preferably 30 to 90 mol%, more preferably 30 to 80 mol%, further preferably 30 to 70 mol%, further preferably 30 to 60 mol%, further preferably 30 to 50 mol%.

[0045] From the viewpoint of heat resistance, linear expansion coefficient, elongation and mechanical strength, the total amount of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 70 mol% or more and 100 mol% or less relative to all repeating units of the polyimide resin precursor, preferably 80 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less, further preferably 95 mol% or more and 100 mol% or less, and still more preferably 99 mol% or more and 100 mol% or less.

[0046] From the viewpoint of transparency, the repeating unit represented by the general formula (1) is preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more, relative to all repeating units of the polyimide resin precursor. The upper limit is 100 mol% or less.

[0047] The polyimide resin precursor may contain a repeating unit other than the repeating unit represented by the general formula (1) or the repeating unit represented by the general formula (2) within a range not impairing the effects of the present invention.

[0048] The content of repeating units other than the repeating units represented by the general formula (1) or the repeating units represented by the general formula (2) relative to all repeating units of the aforementioned polyimide resin precursor is preferably 30 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, further preferably 5 mol% or less, further preferably 1 mol% or less, further preferably 0 mol%, and further preferably not contained.

[0049] <Structural Units of Polyimide Resin Precursor>

[0050] The polyimide resin precursor comprises a repeating unit represented by the general formula (1) and may further comprise a repeating unit represented by the general formula (2). The structural units constituting the precursor are described below.

[0051] The polyimide resin precursor has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine.

[0052] In addition, in the polyimide resin precursor, the structural unit A and the structural unit B form an amic acid structure.

[0053] Since the polyimide resin precursor of the present invention includes the repeating unit represented by the general formula (1), the structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1), and the structural unit B includes a structural unit (B1) derived from a compound represented by the following formula (b1).

[0054]

[0055] (In formula (b1), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0056] Furthermore, the polyimide resin precursor of the present invention includes a repeating unit represented by the aforementioned general formula (1) and may also include a repeating unit represented by the aforementioned general formula (2), so that the structural unit A includes a structural unit (A1) derived from a compound represented by the above formula (a1) and may also include a structural unit (A2) derived from a compound represented by the following formula (a2).

[0057]

[0058] (Structural unit A)

[0059] The structural unit A is a structural unit derived from tetracarboxylic dianhydride, and includes at least a structural unit (A1) derived from a compound represented by the aforementioned formula (a1). It may also include both a structural unit (A1) derived from a compound represented by the aforementioned formula (a1) and a structural unit (A2) derived from a compound represented by the aforementioned formula (a2).

[0060] The compound represented by formula (a1) is 4,4'-oxydiphthalic anhydride (ODPA). By using the structural unit (A1) derived from the compound represented by formula (a1) as the structural unit of the polyimide resin precursor, a polyimide resin precursor capable of producing a polyimide resin having excellent heat resistance and strength and also excellent transparency can be obtained.

[0061] The compound represented by formula (a2) is 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA). By using the structural unit (A2) derived from the compound represented by formula (a2) as a structural unit of the polyimide resin precursor, the heat resistance and strength of the obtained polyimide resin can be further improved.

[0062] The total ratio of the structural unit (A1) and the structural unit (A2) in the structural unit A is preferably 70 mol% or more and 100 mol% or less. It is more preferably 80 mol% or more and 100 mol% or less, further preferably 90 mol% or more and 100 mol% or less, further preferably 95 mol% or more and 100 mol% or less, and further preferably 99 mol% or more and 100 mol% or less.

[0063] The ratio of the structural unit (A1) to the total of the structural unit (A1) and the structural unit (A2) is preferably 30 to 100 mol%, more preferably 40 to 100 mol%, more preferably 50 to 100 mol%, more preferably 60 to 100 mol%, more preferably 70 to 100 mol%, more preferably 80 to 100 mol%, more preferably 90 to 100 mol%, and may be 100 mol%. In addition, from the viewpoint of heat resistance and strength, it is more preferably 30 to 90 mol%, more preferably 30 to 80 mol%, more preferably 30 to 70 mol%, more preferably 30 to 60 mol%, and more preferably 30 to 50 mol%.

[0064] From the viewpoint of transparency, the ratio of the structural unit (A1) in the structural unit A is preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more. The upper limit is 100 mol% or less.

[0065] The structural unit A may contain structural units other than the structural unit (A1) or the structural unit (A2). Such structural units are not particularly limited, and examples thereof include structural units derived from aromatic tetracarboxylic dianhydrides, structural units derived from alicyclic tetracarboxylic dianhydrides, and structural units derived from aliphatic tetracarboxylic dianhydrides other than the structural unit (A1) or the structural unit (A2).

[0066] Examples of the aromatic tetracarboxylic dianhydride that provides a structural unit derived from an aromatic tetracarboxylic dianhydride other than the structural unit (A1) or the structural unit (A2) include 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 2,2',3,3'-benzophenonetetracarboxylic dianhydride.

[0067] As an alicyclic tetracarboxylic dianhydride which provides the structural unit derived from an alicyclic tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, dicyclohexyltetracarboxylic dianhydride, etc. are mentioned.

[0068] As an aliphatic tetracarboxylic dianhydride which provides the structural unit derived from an aliphatic tetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride etc. are mentioned.

[0069] The structural unit optionally contained in the structural unit A may be one kind or two or more kinds.

[0070] It should be noted that, in the present specification, aromatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more alicyclic rings and no aromatic ring, and aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.

[0071] (Structural unit B)

[0072] The structural unit B is a structural unit derived from a diamine, and includes a structural unit (B1) derived from a compound represented by the following formula (b1).

[0073]

[0074] (In formula (b1), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0075] By including the structural unit (B1) in the structural unit B, a polyimide resin precursor capable of producing a polyimide resin having excellent heat resistance and strength can be obtained.

[0076] In the above formula (b1), R 1 , R 2 , R 3 Each independently represents at least one selected from the group consisting of a methyl group, a fluoro group and a trifluoromethyl group, and is preferably a methyl group.

[0077] In the above formula (b1), h, i, and j are each independently an integer of 0 to 4, and preferably 0.

[0078] The ratio of the structural unit (B1) in the structural unit B is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, further preferably 95 mol% or more, further preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol% or less.

[0079] Among the compounds represented by the above formula (b1), preferred are compounds represented by the following formula (b11).

[0080]

[0081] The compound represented by formula (b11) is bis(4-aminophenyl)terephthalate (APTP). The structural unit B preferably includes a structural unit (B11) derived from the compound represented by formula (b11).

[0082] By using the structural unit (B11) derived from the compound represented by the formula (b11) as the structural unit of the polyimide resin precursor, a polyimide resin precursor capable of producing a polyimide resin having excellent heat resistance and strength can be obtained.

[0083] The structural unit B may contain structural units other than the structural unit (B1). Such structural units are not particularly limited, and examples thereof include structural units derived from aromatic diamines, structural units derived from alicyclic diamines, and structural units derived from aliphatic diamines other than the structural unit (B1).

[0084] Examples of the aromatic diamine that provides the structural unit derived from the aromatic diamine other than the structural unit (B1) include 2,2'-bis(trifluoromethyl)benzidine (TFMB), 3,5-diaminobenzoic acid (3,5-DABA), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4-aminophenyl-4-aminobenzoate (4-BAAB), p-phenylenediamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diamine, Aminodiphenylmethane, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane and 1,4-bis(4-aminophenoxy)benzene, etc.

[0085] As an alicyclic diamine which provides the structural unit derived from an alicyclic diamine, 1, 3- bis (aminomethyl) cyclohexane, 1, 4- bis (aminomethyl) cyclohexane, etc. are mentioned.

[0086] Examples of the aliphatic diamine that provides a structural unit derived from an aliphatic diamine include ethylenediamine and hexamethylenediamine.

[0087] In the present specification, aromatic diamine refers to a diamine containing one or more aromatic rings, alicyclic diamine refers to a diamine containing one or more alicyclic rings and no aromatic ring, and aliphatic diamine refers to a diamine containing neither an aromatic ring nor an alicyclic ring.

[0088] The structural unit optionally contained in the structural unit B may be one kind or two or more kinds.

[0089] (Method for producing polyimide resin precursor)

[0090] The polyimide resin precursor may be produced by any method, but is preferably produced by the following production method.

[0091] As described above, the polyimide resin precursor includes a repeating unit represented by the general formula (1) or includes a repeating unit represented by the general formula (1) and a repeating unit represented by the general formula (2) (both of which are amic acids).

[0092] Specifically, it is preferred to use the following production method: a production method in which a tetracarboxylic acid component constituting a polyamic acid containing a repeating unit represented by the aforementioned general formula (1) is reacted with a diamine component to obtain a polyimide resin precursor; or a production method in which a tetracarboxylic acid component and a diamine component constituting a polyamic acid containing a repeating unit represented by the aforementioned general formula (1) are reacted with a tetracarboxylic acid component and a diamine component constituting a polyamic acid containing a repeating unit represented by the aforementioned general formula (2) to obtain a polyimide resin precursor.

[0093] The tetracarboxylic acid component used in the present production method preferably contains a compound that provides the structural unit (A1), may contain a compound that provides the structural unit (A2), and may contain a tetracarboxylic acid component other than the compound that provides the structural unit (A1) or the compound that provides the structural unit (A2) within a range that does not impair the effects of the present invention.

[0094] The diamine component used in the present production method preferably contains a compound that provides the structural unit (B1), and may contain a diamine component other than the compound that provides the structural unit (B1) within a range that does not impair the effects of the present invention.

[0095] In addition, it is preferable to make the quantity of a diamine component into 0.9-1.1 mol with respect to a tetracarboxylic acid component.

[0096] In this production method, there is no limitation in particular on the method for making a tetracarboxylic acid component and a diamine component react, and a well-known method can be used.

[0097] Specific examples of the reaction method include a method of placing a tetracarboxylic acid component, a diamine component, a solvent and, if necessary, a terminal blocking agent in a reactor and stirring at 0 to 120° C., preferably 5 to 80° C., for 1 to 72 hours.

[0098] When the reaction is performed at 80° C. or lower, the molecular weight of the polyimide resin precursor does not vary depending on the temperature history during polymerization, and the progress of thermal imidization can be suppressed, so that the polyimide resin precursor as a polyamic acid can be stably produced.

[0099] By the above method, a polyimide resin precursor solution having a polyamic acid structure dissolved in a solvent is obtained.

[0100] The concentration of the polyimide resin precursor in the obtained solution is preferably 1 to 50% by mass, more preferably 3 to 35% by mass, and further preferably 5 to 30% by mass.

[0101] The polyimide resin precursor obtained by the above production method preferably has a number average molecular weight of 5,000 to 500,000 from the viewpoint of mechanical strength of the obtained polyimide film. From the same viewpoint, the weight average molecular weight (Mw) is preferably 10,000 to 800,000, more preferably 100,000 to 300,000.

[0102] Next, the raw materials and the like used in the present production method will be described.

[0103] [Tetracarboxylic acid component]

[0104] The tetracarboxylic acid component used as a raw material in the present production method is preferably the tetracarboxylic dianhydride described in the above (structural unit (A)). It should be noted that the tetracarboxylic dianhydride used as the tetracarboxylic acid component in the present production method may be any form of dianhydride, tetracarboxylic acid (free acid), and alkyl ester of tetracarboxylic acid, preferably dianhydride.

[0105] The tetracarboxylic acid component used as a raw material in the present production method contains at least a compound represented by the above formula (a1) (a compound providing the structural unit (A1)). It may also contain both a compound represented by the above formula (a1) and a compound represented by the above formula (a2) (a compound providing the structural unit (A2)).

[0106] The total ratio of the compound represented by formula (a1) and the compound represented by formula (a2) in the tetracarboxylic acid component is preferably 70 mol% or more and 100 mol% or less. It is more preferably 80 mol% or more and 100 mol% or less, further preferably 90 mol% or more and 100 mol% or less, further preferably 95 mol% or more and 100 mol% or less, and further preferably 99 mol% or more and 100 mol% or less.

[0107] The ratio of the compound represented by formula (a1) to the total of the compound represented by formula (a1) and the compound represented by formula (a2) is preferably 30 to 100 mol%, more preferably 40 to 100 mol%, more preferably 50 to 100 mol%, more preferably 60 to 100 mol%, more preferably 70 to 100 mol%, more preferably 80 to 100 mol%, more preferably 90 to 100 mol%, and may be 100 mol%. In addition, from the viewpoint of heat resistance and strength, it is more preferably 30 to 90 mol%, more preferably 30 to 80 mol%, more preferably 30 to 70 mol%, more preferably 30 to 60 mol%, and more preferably 30 to 50 mol%.

[0108] From the viewpoint of transparency, the ratio of the compound represented by formula (a1) in the tetracarboxylic acid component is preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more. The upper limit is 100 mol% or less.

[0109] The tetracarboxylic acid component may include a tetracarboxylic acid component other than the compound represented by formula (a1) or the compound represented by formula (a2). Such a tetracarboxylic acid component is not particularly limited, and aromatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aliphatic tetracarboxylic dianhydrides other than the compound represented by formula (a1) or the compound represented by formula (a2) can be listed.

[0110] As a specific example of the tetracarboxylic acid component other than the compound represented by formula (a1) or the compound represented by formula (a2), the tetracarboxylic dianhydride demonstrated in the said (structural unit (A)) section is mentioned.

[0111] These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

[0112] [Diamine component]

[0113] The diamine component used as a raw material in the present production method contains a compound represented by the above formula (b1) (a compound that provides the structural unit (B1)).

[0114] The diamine component used as a raw material in the present production method is preferably the diamine described in the above (structural unit (B)). It should be noted that the diamine used as the diamine component in the present production method may be any form of diamine or diisocyanate corresponding to the diamine, and is preferably diamine.

[0115] The diamine component used as a raw material in the present production method contains a compound represented by the above formula (b1), and preferably contains a compound represented by the formula (b11).

[0116] The ratio of the compound represented by the above formula (b1) in the diamine component is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, further preferably 95 mol% or more, further preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol% or less.

[0117] The diamine component may contain a diamine component other than the compound represented by the above formula (b1). Such a diamine component is not particularly limited, and examples thereof include aromatic diamines, alicyclic diamines, and aliphatic diamines other than the compound providing the structural unit (B1).

[0118] Specific examples of the diamine component other than the compound represented by the above formula (b1) include the diamines described in the above section (structural unit (B)).

[0119] The diamine may be used alone or in combination of two or more.

[0120] [Capping agent]

[0121] Moreover, in the production of the polyimide resin precursor, a terminal blocking agent may be used in addition to the above-mentioned tetracarboxylic acid component and diamine component.

[0122] As the end-capping agent, monoamines or dicarboxylic acids are preferred. The amount of the end-capping agent introduced is preferably 0.0001 to 0.1 moles, and more preferably 0.001 to 0.06 moles, relative to 1 mole of the tetracarboxylic acid component. As monoamine end-capping agents, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. can be cited. Among them, benzylamine and aniline are preferred. As dicarboxylic acid end-capping agents, dicarboxylic acids are preferred, and a part of them can be cyclized. 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, etc. can be cited. Among them, phthalic acid and phthalic anhydride are more preferred.

[0123] [Solvent (organic solvent)]

[0124] The solvent (organic solvent) used in the production of the polyimide resin precursor may be any solvent as long as it can dissolve the generated polyimide resin precursor, and examples thereof include aprotic solvents, phenolic solvents, ether solvents, carbonate solvents, and the like.

[0125] Specific examples of aprotic solvents include amide solvents such as N,N-dimethylformamide, N,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 hexamethylphosphoric acid amide and hexamethylphosphine triamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and cyclopentane; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methylcyclohexanone; and ester solvents such as (2-methoxy-1-methylethyl) acetate.

[0126] Specific examples of the phenolic 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.

[0127] 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.

[0128] Specific examples of the carbonate-based solvent include diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, and propylene carbonate.

[0129] Among the above solvents, amide solvents or lactone solvents are preferred, amide solvents are more preferred, and N-methyl-2-pyrrolidone is further preferred. The above solvents may be used alone or in combination of two or more.

[0130] [Varnish]

[0131] The varnish of the present invention contains the polyimide resin precursor and an organic solvent. That is, the polyimide resin precursor is dissolved in the organic solvent.

[0132] The organic solvent is not particularly limited as long as it dissolves the polyimide resin precursor. As the solvent used in the production of the polyimide resin precursor, it is preferred to use the above-mentioned compounds alone or in combination of two or more.

[0133] The varnish of the present invention may be the polyimide resin precursor solution itself after the production of the polyimide resin precursor, or may be a solution obtained by further mixing the polyimide resin precursor solution with a dilution solvent.

[0134] From the viewpoint of efficiently carrying out the imidization of the polyamic acid as the polyimide resin precursor of the present invention, the varnish of the present invention may further contain an imidization catalyst and a dehydration catalyst. As the imidization catalyst, any imidization catalyst having a boiling point of 40° C. or higher may be used. If the imidization catalyst has a boiling point of 40° C. or higher, the possibility of volatilization before the imidization is fully carried out can be avoided.

[0135] Examples of the imidization catalyst include amine compounds such as pyridine and picoline, and imidazole compounds such as imidazole, 1,2-dimethylimidazole, 1-benzylimidazole, 1-benzyl-2-methylimidazole, and benzimidazole. The imidization catalysts may be used alone or in combination of two or more.

[0136] Examples of the dehydration catalyst include acid anhydrides such as acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride; and carbodiimide compounds such as dicyclohexylcarbodiimide. These may be used alone or in combination of two or more.

[0137] The polyimide resin precursor contained in the varnish of the present invention has solvent solubility, so it can be made into a high-concentration varnish that is stable at room temperature. The varnish of the present invention preferably contains 3 to 40% by mass of the polyimide resin precursor (polyamic acid), and more preferably contains 5 to 30% by mass. The viscosity of the varnish is preferably 0.1 to 100 Pa·s, and more preferably 0.1 to 20 Pa·s. The viscosity of the varnish is a value measured at 25°C using an E-type viscometer.

[0138] The varnish of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoamers, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitizers within a range that does not impair the required properties of the obtained polyimide resin and polyimide film.

[0139] The method for producing the varnish of the present invention is not particularly limited, and a known method can be applied. For example, the varnish can be produced by further mixing a solvent as necessary with the solution of the polyimide resin precursor obtained by the above-mentioned production method and adjusting the concentration.

[0140] [Polyimide film and method for producing polyimide film]

[0141] The polyimide film of the present invention is preferably produced using the above-mentioned varnish.

[0142] The polyimide film of the present invention is obtained by imidizing the above-mentioned polyimide resin precursor. In addition, the polyimide film comprising the following polyimide resin is also included in the present invention, wherein the polyimide resin comprises a repeating unit represented by the general formula (3) described later, or comprises a repeating unit represented by the general formula (3) and a repeating unit represented by the following general formula (4), the total of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) relative to all the repeating units of the polyimide resin is 70 mol% or more and 100 mol% or less, and the ratio of the repeating unit represented by the general formula (3) to the total of the repeating unit represented by the general formula (3) and the repeating unit represented by the following general formula (4) is 30 to 100 mol%.

[0143] In the polyimide film of the present invention, the total amount of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 70 mol% or more and 100 mol% or less relative to all repeating units of the polyimide resin constituting the polyimide film, preferably 80 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less, further preferably 95 mol% or more and 100 mol% or less, and still more preferably 99 mol% or more and 100 mol% or less.

[0144] The method for using varnish of the present invention to manufacture polyimide film is not particularly limited, and known method can be used.For example, varnish of the present invention is applied on a smooth support such as glass plate, metal plate, plastics, or after being formed into a film shape, organic solvents such as reaction solvent, dilution solvent contained in the varnish are removed by heating to obtain polyamic acid film, the polyamic acid in the polyamic acid film is imidized (dehydration cyclization) by heating, then peeled off from the support, thus polyimide film can be manufactured.

[0145] That is, the polyimide film of the present invention is preferably a film obtained by applying the varnish on a support and heating the film, and the method for producing the polyimide film of the present invention is preferably a method of applying the varnish on a support and heating the film.

[0146] As the heating temperature when the varnish containing the polyimide resin precursor is dried to obtain a polyimide resin precursor (polyamic acid) film, it is preferably 50 to 150 ° C. As the heating temperature when the polyimide resin precursor is imidized by heating, it is preferably 350 to 450 ° C, and more preferably 380 to 420 ° C. In addition, the heating time is usually 1 minute to 6 hours, preferably 5 minutes to 2 hours, and more preferably 15 minutes to 1 hour. By setting such a temperature and time, the physical properties of the obtained polyimide film become good.

[0147] The heating atmosphere includes air, nitrogen, oxygen, hydrogen, nitrogen / hydrogen mixed gas, etc. In order to suppress the coloration of the obtained polyimide resin, nitrogen with an oxygen concentration of 100 ppm or less and nitrogen / hydrogen mixed gas containing a hydrogen concentration of 0.5% or less are preferred.

[0148] It should be noted that the imidization method is not limited to thermal imidization, and chemical imidization may also be applied.

[0149] The thickness of the polyimide film of the present invention can be appropriately selected according to the purpose, and is preferably 1 μm or more, more preferably 5 μm or more, and further preferably 7 μm or more. In addition, it is preferably 250 μm or less, more preferably 100 μm or less, further preferably 50 μm or less, and further preferably 20 μm or less. Among them, the thickness of the polyimide film is further preferably 1 μm or more and 20 μm or less. By making the thickness within the above range, it can be used practically as a self-supporting film.

[0150] The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the varnish.

[0151] Suitable physical property values ​​of the polyimide film of the present invention are as follows.

[0152] The glass transition temperature (Tg) is preferably 425°C or higher, more preferably 430°C or higher, further preferably 440°C or higher, and further preferably 445°C or higher.

[0153] The tensile elongation of the polyimide film at 23° C. and 50% RH when the thickness is 10 μm is preferably 12% or more, more preferably 15% or more, further preferably 17% or more, and further preferably 19% or more.

[0154] The total light transmittance of the polyimide film when the thickness is 10 μm is preferably 80% or more, more preferably 81% or more.

[0155] The tensile strength of the polyimide film at a thickness of 10 μm (according to JIS K7127:1999, 23° C., 50% RH) is preferably 235 MPa or more, more preferably 240 MPa or more, further preferably 250 MPa or more, and further preferably 260 MPa or more when the film is made into a film with a thickness of 10 μm.

[0156] The coefficient of linear expansion (CTE) is preferably 15 ppm / °C or less, more preferably 7 ppm / °C or less, and further preferably 5 ppm / °C or less. There is no restriction on the lower limit, but from the viewpoint of reducing the difference in thermal expansion coefficient with the support and the inorganic layer constituting the device, it is preferably 1 ppm / °C or more, more preferably 2 ppm / °C or more, and further preferably 3 ppm / °C or more.

[0157] It should be noted that the above-mentioned physical property values ​​in the present invention can be specifically measured by the methods described in the Examples.

[0158] The polyimide film of the present invention is suitable for use as a film for various components such as color filters, flexible displays, semiconductor components, optical components, etc. 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.

[0159] [Polyimide resin]

[0160] The polyimide resin of the present invention contains a repeating unit represented by the following general formula (3), or contains a repeating unit represented by the following general formula (3) and a repeating unit represented by the following general formula (4), wherein the total amount of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin, and the ratio of the repeating unit represented by the general formula (3) to the total amount of the repeating unit represented by the general formula (3) and the repeating unit represented by the following general formula (4) is 30 to 100 mol%.

[0161]

[0162] (In formula (3) and formula (4), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0163] Furthermore, the polyimide resin of the present invention constitutes the polyimide film, and the polyimide film contains the polyimide resin of the present invention.

[0164] The polyimide resin of the present invention can be obtained by any production method, but a method of producing the polyimide resin by imidizing the above-mentioned polyimide resin precursor is preferred.

[0165] The reason why the polyimide resin of the present invention and the polyimide film containing the same have excellent heat resistance, a low linear expansion coefficient, and further excellent elongation and mechanical strength is not yet clear, but is considered to be as follows.

[0166] It is believed that among aromatic diamines, specific diamines having an ester skeleton as a bonding group of an aromatic ring have high rigidity, and a copolymer formed from a component derived from a specific aromatic tetracarboxylic dianhydride and the aforementioned diamine component having a specific ester skeleton can achieve both a low linear expansion coefficient and high heat resistance required for TFT substrates, etc.

[0167] On the other hand, when rigidity becomes too high, there is a tendency that elongation and mechanical strength reduce. In addition, the higher the molecular weight of the polyimide is, the more the elongation and mechanical strength increase. It is believed that the polyimide of the present invention is copolymerized with a specific acid dianhydride with a soft ether skeleton and a specific acid dianhydride with a rigid skeleton in an appropriate ratio, and then copolymerized with an aromatic diamine with a specific ester skeleton high in nucleophilicity in order to increase the molecular weight, thereby taking into account the aforementioned low linear expansion coefficient, the basis of high heat resistance, also has excellent elongation, mechanical strength.

[0168] In addition, the "repeating unit" in a polyimide resin means an imide unit containing one structural unit derived from tetracarboxylic dianhydride and one structural unit derived from a diamine.

[0169] In the above formula (3), R 1 , R 2 , R 3 Each independently represents at least one selected from the group consisting of a methyl group, a fluoro group and a trifluoromethyl group, and is preferably a methyl group.

[0170] In the above formula (3), h, i, and j are each independently an integer of 0 to 4, and preferably 0.

[0171] In the above formula (4), R 1 , R 2 , R 3 Each independently represents at least one selected from the group consisting of a methyl group, a fluoro group and a trifluoromethyl group, and is preferably a methyl group.

[0172] In the above formula (4), h, i, and j are each independently an integer of 0 to 4, and preferably 0.

[0173] As described above, the polyimide resin contains the repeating unit represented by the above-mentioned general formula (3), and may contain the repeating unit represented by the above-mentioned general formula (4).

[0174] The ratio of the repeating unit represented by the general formula (3) to the total of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 30 to 100 mol%, preferably 40 to 100 mol%, more preferably 50 to 100 mol%, further preferably 60 to 100 mol%, further preferably 70 to 100 mol%, further preferably 80 to 100 mol%, further preferably 90 to 100 mol%, and may be 100 mol%. In addition, from the viewpoint of heat resistance and strength, it is preferably 30 to 90 mol%, more preferably 30 to 80 mol%, further preferably 30 to 70 mol%, further preferably 30 to 60 mol%, further preferably 30 to 50 mol%.

[0175] From the viewpoints of heat resistance, linear expansion coefficient, elongation and mechanical strength, the sum of the repeating units represented by the general formula (3) and the repeating units represented by the general formula (4) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin, preferably 80 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less, further preferably 95 mol% or more and 100 mol% or less, and still more preferably 99 mol% or more and 100 mol% or less.

[0176] From the viewpoint of transparency, the repeating unit represented by the general formula (3) is preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more relative to all the repeating units of the polyimide resin. The upper limit is 100 mol% or less.

[0177] The polyimide resin may contain a repeating unit other than the repeating unit represented by the general formula (3) or the repeating unit represented by the general formula (4) within a range not impairing the effects of the present invention.

[0178] The content of repeating units other than the repeating units represented by the general formula (3) or the repeating units represented by the general formula (4) relative to all repeating units of the aforementioned polyimide resin is preferably 30 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, further preferably 5 mol% or less, further preferably 1 mol% or less, further preferably 0 mol%, and further preferably not contained.

[0179] <Structural Units of Polyimide Resin>

[0180] The polyimide resin includes a repeating unit represented by the general formula (3) and may further include a repeating unit represented by the general formula (4). The structural units constituting the polyimide resin are the same as those described in the above section <Structural units of polyimide resin precursor>.

[0181] That is, the polyimide resin has a structural unit AI derived from tetracarboxylic dianhydride and a structural unit BI derived from a diamine.

[0182] It should be noted that, in the polyimide resin, the structural unit AI and the structural unit BI form an imide structure.

[0183] The polyimide resin of the present invention comprises the repeating unit represented by the general formula (3). Therefore, the structural unit AI comprises a structural unit (AI1) derived from a compound represented by the following formula (a1), and the structural unit BI comprises a structural unit (BI1) derived from a compound represented by the following formula (b1).

[0184]

[0185] (In formula (b1), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0186] Furthermore, the polyimide resin of the present invention may include a repeating unit represented by the aforementioned general formula (3) and a repeating unit represented by the aforementioned general formula (4), so the structural unit AI includes a structural unit (AI1) derived from a compound represented by the aforementioned formula (a1), and may also include a structural unit (AI2) derived from a compound represented by the following formula (a2).

[0187]

[0188] The structural unit AI is a structural unit derived from tetracarboxylic dianhydride and contains at least a structural unit (AI1) derived from the compound represented by the above formula (a1). It may also contain both a structural unit (AI1) derived from the compound represented by the above formula (a1) and a structural unit (AI2) derived from the compound represented by the above formula (a2).

[0189] The compound represented by formula (a1) is 4,4'-oxydiphthalic anhydride (ODPA). When the structural unit (AI1) derived from the compound represented by formula (a1) is used as the structural unit of the polyimide resin, the polyimide resin has excellent heat resistance and strength, and also excellent transparency.

[0190] The compound represented by formula (a2) is 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA). When the structural unit (AI2) derived from the compound represented by formula (a2) is used as a structural unit of the polyimide resin, the heat resistance and strength can be further improved.

[0191] The total ratio of the structural unit (AI1) and the structural unit (AI2) in the structural unit AI is preferably 70 mol% or more and 100 mol% or less. It is more preferably 80 mol% or more and 100 mol% or less, further preferably 90 mol% or more and 100 mol% or less, further preferably 95 mol% or more and 100 mol% or less, and further preferably 99 mol% or more and 100 mol% or less.

[0192] The ratio of the structural unit (AI1) to the total of the structural unit (AI1) and the structural unit (AI2) is preferably 30 to 100 mol%, more preferably 40 to 100 mol%, more preferably 50 to 100 mol%, more preferably 60 to 100 mol%, more preferably 70 to 100 mol%, more preferably 80 to 100 mol%, more preferably 90 to 100 mol%, and may be 100 mol%. In addition, from the viewpoint of heat resistance and strength, it is more preferably 30 to 90 mol%, more preferably 30 to 80 mol%, more preferably 30 to 70 mol%, more preferably 30 to 60 mol%, and more preferably 30 to 50 mol%.

[0193] From the viewpoint of transparency, the ratio of the structural unit (AI1) in the structural unit AI is preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, further preferably 70 mol% or more, further preferably 80 mol% or more, further preferably 90 mol% or more. The upper limit is 100 mol% or less.

[0194] The structural unit AI may contain structural units other than the structural unit (AI1) or the structural unit (AI2). Such structural units are not particularly limited, and examples thereof include structural units derived from aromatic tetracarboxylic dianhydrides, structural units derived from alicyclic tetracarboxylic dianhydrides, and structural units derived from aliphatic tetracarboxylic dianhydrides other than the structural unit (AI1) or the structural unit (AI2).

[0195] Examples of the aromatic tetracarboxylic dianhydride that provides a structural unit derived from an aromatic tetracarboxylic dianhydride other than the structural unit (AI1) or the structural unit (AI2) include 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 2,2',3,3'-benzophenone tetracarboxylic dianhydride.

[0196] As an alicyclic tetracarboxylic dianhydride which provides the structural unit derived from an alicyclic tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, dicyclohexyltetracarboxylic dianhydride, etc. are mentioned.

[0197] As an aliphatic tetracarboxylic dianhydride which provides the structural unit derived from an aliphatic tetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride etc. are mentioned.

[0198] The structural unit optionally contained in the structural unit AI may be one type or two or more types.

[0199] It should be noted that in the present specification, aromatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more alicyclic rings and no aromatic ring, and aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.

[0200] (Structural unit BI)

[0201] The structural unit BI is a structural unit derived from a diamine, and includes a structural unit (BI1) derived from a compound represented by the following formula (b1).

[0202]

[0203] (In formula (b1), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group. h, i and j are integers of 0 to 4.)

[0204] By including the structural unit (BI1) in the structural unit BI, the polyimide resin can be made excellent in heat resistance and strength.

[0205] In the above formula (b1), R 1 , R 2 , R 3 Each independently represents at least one selected from the group consisting of a methyl group, a fluoro group and a trifluoromethyl group, and is preferably a methyl group.

[0206] In the above formula (b1), h, i, and j are each independently an integer of 0 to 4, and preferably 0.

[0207] The ratio of the structural unit (BI1) in the structural unit BI is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, further preferably 95 mol% or more, further preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, and is 100 mol% or less.

[0208] Among the compounds represented by the above formula (b1), preferred are compounds represented by the following formula (b11).

[0209]

[0210] The compound represented by formula (b11) is bis(4-aminophenyl)terephthalate (APTP). The structural unit B preferably includes a structural unit (BI11) derived from the compound represented by formula (b11).

[0211] By using the structural unit (BI11) derived from the compound represented by the formula (b11) as the structural unit of the polyimide resin, a polyimide resin having excellent heat resistance and strength can be obtained.

[0212] The structural unit BI may contain structural units other than the structural unit (BI1). Such structural units are not particularly limited, and examples thereof include structural units derived from aromatic diamines, structural units derived from alicyclic diamines, and structural units derived from aliphatic diamines other than the structural unit (BI1).

[0213] Examples of the aromatic diamine that provides a structural unit derived from an aromatic diamine other than the structural unit (BI1) include 2,2'-bis(trifluoromethyl)benzidine (TFMB), 3,5-diaminobenzoic acid (3,5-DABA), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4-aminophenyl-4-aminobenzoate (4-BAAB), p-phenylenediamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'- Diaminodiphenylmethane, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane and 1,4-bis(4-aminophenoxy)benzene, etc.

[0214] As an alicyclic diamine which provides the structural unit derived from an alicyclic diamine, 1, 3- bis (aminomethyl) cyclohexane, 1, 4- bis (aminomethyl) cyclohexane, etc. are mentioned.

[0215] Examples of the aliphatic diamine that provides a structural unit derived from an aliphatic diamine include ethylenediamine and hexamethylenediamine.

[0216] In the present specification, aromatic diamine refers to a diamine containing one or more aromatic rings, alicyclic diamine refers to a diamine containing one or more alicyclic rings and no aromatic ring, and aliphatic diamine refers to a diamine containing neither an aromatic ring nor an alicyclic ring.

[0217] The structural unit optionally contained in the structural unit BI may be one kind or two or more kinds.

[0218] The polyimide resin of the present invention may contain structures other than the polyimide chain (structure formed by imide bonding of structural unit AI and structural unit BI) within the scope of not impairing the present invention. Examples of structures other than the polyimide chain that may be contained in the polyimide resin include structures containing amide bonds.

[0219] The polyimide resin of the present invention preferably comprises a polyimide chain (a structure formed by imide bonding of structural unit AI and structural unit BI) as a main structure. Therefore, the ratio of the polyimide chain in the polyimide resin of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 99% by mass or more, and further preferably 100% by mass.

[0220] Suitable physical property values ​​of the polyimide resin of the present invention are as follows.

[0221] The glass transition temperature (Tg) is preferably 425°C or higher, more preferably 430°C or higher, further preferably 440°C or higher, and further preferably 445°C or higher.

[0222] The tensile elongation at 23° C. and 50% RH when formed into a film having a thickness of 10 μm is preferably 12% or more, more preferably 15% or more, further preferably 17% or more, and further preferably 19% or more.

[0223] The total light transmittance when formed into a film with a thickness of 10 μm is preferably 80% or more, more preferably 81% or more.

[0224] The tensile strength when made into a film with a thickness of 10 μm (according to JIS K7127:1999, 23°C, 50% RH) is preferably 235 MPa or more, more preferably 240 MPa or more, further preferably 250 MPa or more, and further preferably 260 MPa or more.

[0225] The coefficient of linear expansion (CTE) is preferably 15 ppm / °C or less, more preferably 7 ppm / °C or less, and further preferably 5 ppm / °C or less. There is no restriction on the lower limit, but from the viewpoint of reducing the difference in thermal expansion coefficient with the support and the inorganic layer constituting the device, it is preferably 1 ppm / °C or more, more preferably 2 ppm / °C or more, and further preferably 3 ppm / °C or more.

[0226] It should be noted that the above-mentioned physical property values ​​in the present invention can be specifically measured by the methods described in the Examples.

[0227] Example

[0228] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples in any way.

[0229] <Thin film properties and evaluation>

[0230] The physical properties of the thin films obtained in Examples and Comparative Examples were measured by the methods shown below.

[0231] (1) Film thickness

[0232] The film thickness was measured using a digital meter SA-S110 / 03N manufactured by CITIZEN FINEDEVICE CO., LTD.

[0233] (2) Total light transmittance

[0234] The total light transmittance of the polyimide films of Examples and Comparative Examples was measured in accordance with JIS K7361-1 (D illuminant, 65°) using a color / turbidity simultaneous measuring device “COH7700” manufactured by Nippon Denshoku Industries Co., Ltd.

[0235] (3) Glass transition temperature (Tg)

[0236] The TMA measurement was performed using a thermomechanical analyzer "TMA7100C" manufactured by Hitachi High-Tech Science Corporation, with a sample size of 4 mm × 20 mm, in a tensile mode, under a load of 50 mN, and a heating rate of 10 ° C / min, from 40 ° C to 500 ° C. The inflection point of the elongation was observed by extrapolation as the glass transition temperature (Tg). The larger the value of the glass transition temperature (Tg), the better the heat resistance.

[0237] (4) Coefficient of linear expansion (CTE)

[0238] Using a thermomechanical analyzer "TMA7100C" manufactured by Hitachi High-Tech Science Corporation, TMA measurement was performed with a sample size of 4 mm × 20 mm, a load of 50 mN, and a heating rate of 10°C / min, and the temperature was raised from 40°C to 500°C. The CTE of 100 to 200°C was obtained and evaluated according to the following criteria. In addition, the difference in thermal expansion coefficient with the supporting substrate (alkali-free glass, AN100) (thermal expansion coefficient of 50 to 350°C: 3.8 ppm / °C) is also shown in Table 1. When the difference in thermal expansion coefficient with the supporting substrate is small, it is difficult to cause peeling at the bonding surface, so it is good.

[0239] (Evaluation Criteria)

[0240] A: less than 7ppm / ℃

[0241] B: 7ppm / ℃ or more and less than 15ppm / ℃

[0242] C: 15ppm / ℃ or above

[0243] (5) Tensile strength, tensile elastic modulus, tensile elongation

[0244] The tensile strength, tensile modulus and tensile elongation were measured according to JIS K7127: 1999 using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. (measurement environment: 23°C, 50% RH). The distance between the chucks was set to 50 mm, the test piece size was set to 10 mm × 70 mm, and the test speed was set to 20 mm / min. The larger the value of the tensile strength, the better the mechanical strength.

[0245] The tetracarboxylic acid component and the diamine component used in the Examples and Comparative Examples, and their abbreviations and the like are as follows.

[0246] <Tetracarboxylic acid component>

[0247] ODPA: 4,4'-oxydiphthalic anhydride (manufactured by MANAC Co., Ltd.; compound represented by formula (a1))

[0248] s-BPDA: 3,3′,4,4′-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation, a compound represented by formula (a2))

[0249] <Diamine component>

[0250] APTP: bis(4-aminophenyl)terephthalate (manufactured by Tokyo Chemical Industry Co., Ltd.; compound represented by formula (b11))

[0251] ABHQ: [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate (manufactured by China Tech Chemical (Tianjin) Co., Ltd., a compound represented by the following formula)

[0252]

[0253] 4-BAAB: 4-aminophenyl-4-aminobenzoate (manufactured by Japan Junryo Pharmaceutical Co., Ltd.; a compound represented by the following formula)

[0254]

[0255] PPD: p-phenylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0256] The abbreviations of the solvents (medium) used in Examples and Comparative Examples are as follows.

[0257] NMP: N-methyl-2-pyrrolidone (manufactured by Tokyo Junyaku Industries Co., Ltd.)

[0258] Example 1

[0259] In a 300 mL 5-necked round-bottom flask equipped with a stainless steel half-moon-shaped stirring blade, a Dean-Stark apparatus equipped with a nitrogen inlet pipe and a cooling pipe, a thermometer, and a glass end cap, 6.967 g (0.020 mol) of APTP and 59.710 g of NMP were added, and the mixture was stirred at a temperature of 50° C. in a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.

[0260] To this solution, 6.204 g (0.020 mol) of ODPA and 14.928 g of NMP were added all at once, and the solution was stirred for 5 hours while being maintained at 50° C. with an electric heating mantle.

[0261] Then, 43.905 g of NMP was added, and the mixture was further stirred for 1 hour for homogenization to obtain a polyamic acid varnish having a solid content concentration of 10% by mass.

[0262] Next, the obtained polyamic acid varnish was applied to a supporting substrate (alkali-free glass, AN100, manufactured by AGC Co., Ltd.), maintained at 80° C. for 20 minutes using a hot plate, and then heated to 400° C. at a heating rate of 5° C. / min in a hot air dryer under a nitrogen atmosphere, and heated at 400° C. for 60 minutes to evaporate the solvent and perform thermal imidization to obtain a polyimide film. The evaluation results of the film are shown in Table 1.

[0263] Example 2

[0264] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 1 except that the amount of ODPA was changed from 6.204 g (0.020 mol) to 4.963 g (0.016 mol) and 1.177 g (0.004 mol) of s-BPDA was added.

[0265] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0266] Example 3

[0267] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 1 except that the amount of ODPA was changed from 6.204 g (0.020 mol) to 3.102 g (0.010 mol) and 2.942 g (0.010 mol) of s-BPDA was added.

[0268] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0269] Comparative Example 1

[0270] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 1 except that the amount of ODPA was changed from 6.204 g (0.020 mol) to 1.241 g (0.004 mol) and 4.708 g (0.016 mol) of s-BPDA was added.

[0271] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0272] Comparative Example 2

[0273] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 1 except that 6.204 g (0.020 mol) of ODPA was changed to 5.884 g (0.020 mol) of s-BPDA.

[0274] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0275] Comparative Example 3

[0276] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 1 except that 6.967 g (0.020 mol) of APTP was changed to 6.967 g (0.020 mol) of ABHQ.

[0277] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0278] Comparative Example 4

[0279] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 1 except that 6.967 g (0.020 mol) of APTP was changed to 4.567 g (0.020 mol) of 4-BAAB.

[0280] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0281] Comparative Example 5

[0282] A polyamic acid varnish having a solid content concentration of 10% by mass was obtained by the same method as in Example 3 except that 6.967 g (0.020 mol) of APTP was changed to 4.668 g (0.0134 mol) of APTP and 0.714 g (0.0066 mol) of PPD.

[0283] Using the obtained polyamic acid varnish, a film was obtained by the same method as in Example 1. Table 1 shows the evaluation results of the film.

[0284] [Table 1]

[0285] Table 1

[0286]

[0287] (*1) The numbers in the polyimide resin column indicate the molar ratio of each component.

[0288] As shown in Table 1, it can be seen that the polyimide film obtained using the polyimide resin precursor of the embodiment has a high glass transition temperature, a low linear expansion coefficient, and a large tensile elongation and tensile strength, so it is excellent in heat resistance and strength, and the elongation is also excellent. It can be seen from this that the polyimide resin and polyimide film of the present invention have excellent heat resistance, a low linear expansion coefficient, and excellent elongation and mechanical strength.

Claims

1. A polyimide resin precursor comprising a repeating unit represented by the following general formula (1), or comprising a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), The total amount of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin precursor, The ratio of the repeating unit represented by the general formula (1) to the total of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 30 to 100 mol %; In formula (1) and formula (2), X 1 and X 2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group; and h, i and j are integers of 0-4.

2. The polyimide resin precursor according to claim 1, wherein The ratio of the repeating unit represented by the general formula (1) to the total of the repeating unit represented by the general formula (1) and the repeating unit represented by the general formula (2) is 50 to 100 mol%. 3 . A varnish comprising the polyimide resin precursor according to claim 1 or 2 and an organic solvent. 4 . A polyimide film obtained by applying the varnish according to claim 3 onto a support and heating the coated support.

5. A polyimide resin comprising a repeating unit represented by the following general formula (3), or comprising a repeating unit represented by the following general formula (3) and a repeating unit represented by the following general formula (4), The total amount of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 70 mol% or more and 100 mol% or less relative to all the repeating units of the polyimide resin, The ratio of the repeating unit represented by the general formula (3) to the total of the repeating unit represented by the general formula (3) and the repeating unit represented by the following general formula (4) is 30 to 100 mol %; In formula (3) and formula (4), R 1 , R 2 , R 3 Each independently represents a methyl group, a fluoro group or a trifluoromethyl group; h, i and j are integers of 0 to 4.

6. The polyimide resin according to claim 5, wherein The ratio of the repeating unit represented by the general formula (3) to the total of the repeating unit represented by the general formula (3) and the repeating unit represented by the general formula (4) is 50 to 100 mol%. 7 . A polyimide film comprising the polyimide resin according to claim 5 .

8. The polyimide film according to claim 7, wherein The glass transition temperature is 430° C. or higher, the tensile elongation at 23° C. and 50% RH when the polyimide film has a thickness of 10 μm is 15% or higher, and the total light transmittance when the polyimide film has a thickness of 10 μm is 80% or higher.

9. The polyimide film according to claim 7, wherein The thickness of the polyimide film is 1 μm or more and 20 μm or less.

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