Polyimide, polyimide solution, coating material, and molding material

Abstract

A polyimide having excellent solubility in a solvent is provided. The polyimide is formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride and a diamine component containing 20.0 to 80.0 mol% of a specific compound A and 20.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane.

Description

Technology Field

[0001] The present invention relates to polyimide, polyimide solution, coating material, and molding material. Background Technology

[0002] Polyimide (polyimide resin) possesses not only excellent heat resistance but also characteristics such as chemical resistance, radiation resistance, electrical insulation, and excellent mechanical properties.

[0003] For this reason, polyimide is known as a material used in flexible printed circuit boards, insulating coatings, heat-resistant molding materials, etc.

[0004] Most polyimides with structures used industrially are insoluble in organic solvents and, furthermore, do not melt even above the glass transition temperature. For this reason, it is usually not easy to mold polyimides themselves.

[0005] Generally, polyimide is synthesized, for example, as described in Patent Document 1.

[0006] That is, first, an aromatic tetracarboxylic acid dihydride, such as 3,3',4,4'-biphenyltetracarboxylic acid dihydride, is reacted with an aromatic diamine, such as 1,4-phenylenediamine, in an aprotic polar organic solvent such as N-methyl-2-pyrrolidone to obtain a polyamic acid (polyamic acid) which is a precursor of polyimide.

[0007] Afterwards, this polyamide acid is heated at 250°C to 400°C to proceed with dehydration and cyclization (imidization) to obtain a polyimide. Prior art literature

[0008] Japanese Patent Publication No. Sho 60-42817 The problem to be solved

[0009] Most polyimides with structures used industrially are soluble in organic solvents in the polyamic acid state, but when they become polyimides, they gel or precipitate immediately after synthesis or after being left for about a day, and become insoluble without dissolving.

[0010] For this reason, in order to obtain a material containing polyimide (polyimide material), it is common practice to coat a solution of polyamide acid, volatilize the solvent, and then heat it to induce imidization.

[0011] However, since condensation water is generated during the process of imidizing polyamide acids, voids may occur in the polyimide material. Additionally, the polyimide material may shrink, causing changes in thickness and other properties.

[0012] The present invention is made in consideration of the above points and aims to provide a polyimide with excellent solubility in a solvent (no gelation or precipitation occurs).

[0013] In addition, the present invention also aims to provide a polyimide solution containing the polyimide, a coating material, and a molding material. means of solving the problem

[0014] The inventors have completed the present invention by discovering, through careful consideration, that the above objective is achieved by adopting the following configuration.

[0015] That is, the present invention provides the following [1] to [9].

[0016] [1] A polyimide formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride, 20.0 to 80.0 mol% of compound A described below, and 20.0 to 80.0 mol% of a diamine component containing 2,2-bis-[4-(4-aminophenoxy)phenyl]propane.

[0017] [2] A polyimide formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 20.0 to 80.0 mol% of compound A described below and 20.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane.

[0018] [3] A polyimide formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride and a diamine component containing 15.0 to 80.0 mol% of compound A described below, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane and more than 0.0 mol% and less than 30.0 mol% of 2,4-diaminotoluene.

[0019] [4] A polyimide formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 15.0 to 80.0 mol% of compound A described below, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane and more than 0.0 mol% and less than 30.0 mol% of 2,4-diaminotoluene.

[0020] [5] A polyimide formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride, 15.0 to 80.0 mol% of compound A described below, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and a diamine component containing more than 0.0 mol% and less than 30.0 mol% of 4,4'-oxydianiline and / or 3,4'-oxydianiline.

[0021] [6] A polyimide formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 15.0 to 80.0 mol% of compound A described below, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane and more than 0.0 mol% and less than 30.0 mol% of 4,4'-oxydianiline and / or 3,4'-oxydianiline.

[0022] [7] A polyimide solution containing 5 to 50 mass% of the polyimide described in any one of [1] to [6] above in a polar organic solvent.

[0023] [8] A coating material containing polyimide as described in any of [1] to [6] above.

[0024] [9] A molding material containing polyimide as described in any of [1] to [6] above. Effects of the invention

[0025] According to the present invention, a polyimide with excellent solubility in a solvent can be provided.

[0026] By using a solution containing such polyimide (polyimide solution), the occurrence of voids, etc., in the resulting polyimide material can be suppressed because imidization has already taken place.

[0027] In other words, a polyimide material of any shape is obtained simply by coating a polyimide solution and evaporating the solvent. Furthermore, it possesses comparable mechanical strength and thermal properties. Specific details for implementing the invention

[0028] (Form for carrying out the invention)

[0029] [Polyimide]

[0030] The first to sixth embodiments of the polyimide (polyimide resin) of the present invention are described in detail below. The polyimides of the first to sixth embodiments described below exhibit excellent solubility with respect to a solvent (e.g., a polar organic solvent described later).

[0031] <First Embodiment>

[0032] The polyimide of the first embodiment is formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride, a diamine component containing 20.0 to 80.0 mol% of compound A described below, and 20.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane.

[0033] Acidic components

[0034] The acid component contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0035] Among the acid components, the content of BPDA is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 100.0 mol% for the reason that it balances strength and solubility.

[0036] Diamine component

[0037] The diamine component contains compound A represented by the following formula (A).

[0038]

[0039] R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group.

[0040] As for compound A, suitable examples include 4,4'-methylenebis(2-ethyl-6-methylaniline) (MED) represented by formula (3) described below, 4,4'-methylenebis(2,6-dimethylaniline) (MMD) represented by formula (4) described below, and 4,4'-methylenebis(2,6-diethylaniline) (EED) represented by formula (5) described below.

[0041] Among the diamine components, the content of compound A is 20.0 to 80.0 mol%, preferably 23.0 to 77.0 mol%, and more preferably 25.0 to 75.0 mol%, for the reason that strength and solubility are compatible.

[0042] The diamine component additionally contains 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0043] Among the diamine components, the content of BAPP is 20.0 to 80.0 mol%, 23.0 to 77.0 mol% is preferred, and 25.0 to 75.0 mol% is more preferred, for the reason that strength and solubility are compatible.

[0044] <Second Embodiment>

[0045] The polyimide of the second embodiment is formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 20.0 to 80.0 mol% of compound A and 20.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane.

[0046] Acidic components

[0047] The acid component contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0048] Among the acid components, the content of BPDA is greater than 70.0 mol% and less than 100.0 mol% for the reason that strength and solubility are compatible, 73.0 to 97.0 mol% is preferred, and 75.0 to 90.0 mol% is more preferred.

[0049] The acid component additionally contains pyromellitic acid dianhydride (PMDA).

[0050] Among the acid components, the PMDA content is greater than 0.0 mol% and less than 30.0 mol%, preferably 3.0 to 27.0 mol%, and more preferably 10.0 to 27.0 mol%, for the reason that strength and solubility are compatible.

[0051] Diamine component

[0052] The diamine component contains compound A.

[0053] Among the diamine components, the content of compound A is 20.0 to 80.0 mol%, preferably 23.0 to 77.0 mol%, and more preferably 25.0 to 75.0 mol%, for the reason that strength and solubility are compatible.

[0054] The diamine component additionally contains 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0055] Among the diamine components, the content of BAPP is 20.0 to 80.0 mol%, 23.0 to 77.0 mol% is preferred, and 25.0 to 75.0 mol% is more preferred, for the reason that strength and solubility are compatible.

[0056] <Third Embodiment>

[0057] The polyimide of the third embodiment is formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride and a diamine component containing 15.0 to 80.0 mol% of compound A, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and more than 0.0 mol% and less than 30.0 mol% of 2,4-diaminotoluene.

[0058] Acidic components

[0059] The acid component contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0060] Among the acid components, the content of BPDA is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 100.0 mol% for the reason that it balances strength and solubility.

[0061] Diamine component

[0062] The diamine component contains compound A.

[0063] Among the diamine components, the content of compound A is 15.0 to 80.0 mol%, 20.0 to 70.0 mol% is preferred, and 20.0 to 60.0 mol% is more preferred for the reason that strength and solubility are compatible.

[0064] The diamine component additionally contains 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0065] Among the diamine components, the content of BAPP is 15.0 to 80.0 mol%, preferably 20.0 to 70.0 mol%, and more preferably 25.0 to 60.0 mol%, for the reason that strength and solubility are compatible.

[0066] The diamine component additionally contains 2,4-diaminotoluene (DAT).

[0067] Among the diamine components, the content of DAT is greater than 0.0 mol% and less than 30.0 mol%, preferably 5.0 to 28.0 mol%, and more preferably 10.0 to 27.0 mol%, for the reason that strength and solubility are compatible.

[0068] <Fourth Embodiment>

[0069] The polyimide of the fourth embodiment is formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 15.0 to 80.0 mol% of compound A, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane and more than 0.0 mol% and less than 30.0 mol% of 2,4-diaminotoluene.

[0070] Acidic components

[0071] The acid component contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0072] Among the acid components, the content of BPDA is greater than 70.0 mol% and less than 100.0 mol% for the reason that strength and solubility are compatible, 73.0 to 97.0 mol% is preferred, and 75.0 to 90.0 mol% is more preferred.

[0073] The acid component additionally contains pyromellitic acid dianhydride (PMDA).

[0074] Among the acid components, the content of PMDA is greater than 0.0 mol% and less than 30.0 mol% for the reason that strength and solubility are compatible, 3.0 to 27.0 mol% is preferred, and 10.0 to 25.0 mol% is more preferred.

[0075] Diamine component

[0076] The diamine component contains compound A.

[0077] Among the diamine components, the content of compound A is 15.0 to 80.0 mol%, 20.0 to 60.0 mol% is preferred, and 22.0 to 45.0 mol% is more preferred, for the reason that strength and solubility are compatible.

[0078] The diamine component additionally contains 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0079] Among the diamine components, the content of BAPP is 15.0 to 80.0 mol%, 25.0 to 60.0 mol% is preferred, and 30.0 to 55.0 mol% is more preferred, for the reason that strength and solubility are compatible.

[0080] The diamine component additionally contains 2,4-diaminotoluene (DAT).

[0081] Among the diamine components, the content of DAT is greater than 0.0 mol% and less than 30.0 mol%, preferably 5.0 to 28.0 mol%, and more preferably 10.0 to 27.0 mol%, for the reason that strength and solubility are compatible.

[0082] <Fifth Embodiment>

[0083] The polyimide of the fifth embodiment is formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride and a diamine component containing 15.0 to 80.0 mol% of compound A, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and more than 0.0 mol% and less than 30.0 mol% of 4,4'-oxydianiline and / or 3,4'-oxydianiline.

[0084] Acidic components

[0085] The acid component contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0086] Among the acid components, the content of BPDA is preferably 90.0 mol% or more, more preferably 95.0 mol% or more, and even more preferably 100.0 mol% for the reason that it balances strength and solubility.

[0087] Diamine component

[0088] The diamine component contains compound A.

[0089] Among the diamine components, the content of compound A is 15.0 to 80.0 mol%, preferably 20.0 to 60.0 mol%, and more preferably 23.0 to 52 mol%, for the reason that strength and solubility are compatible.

[0090] The diamine component additionally contains 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0091] Among the diamine components, the content of BAPP is 15.0 to 80.0 mol%, preferably 20.0 to 60.0 mol%, and more preferably 23.0 to 52.0 mol%, for the reason that strength and solubility are compatible.

[0092] The diamine component additionally contains 4,4'-oxydianiline (ODA) and / or 3,4'-oxydianiline (DAPE).

[0093] Among the diamine components, the total content of ODA and DAPE is greater than 0.0 mol% and less than 30.0 mol%, preferably 5.0 to 28.0 mol%, and more preferably 10.0 to 27.0 mol%, for the reason that strength and solubility are compatible.

[0094] <6th Embodiment>

[0095] The polyimide of the 6th embodiment is formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 15.0 to 80.0 mol% of compound A, 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and more than 0.0 mol% and less than 30.0 mol% of 4,4'-oxydianiline and / or 3,4'-oxydianiline.

[0096] Acidic components

[0097] The acid component contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0098] Among the acid components, the content of BPDA is greater than 70.0 mol% and less than 100.0 mol% for the reason that strength and solubility are compatible, 73.0 to 97.0 mol% is preferred, and 75.0 to 90.0 mol% is more preferred.

[0099] The acid component additionally contains pyromellitic acid dianhydride (PMDA).

[0100] Among the acid components, the content of PMDA is greater than 0.0 mol% and less than 30.0 mol% for the reason that strength and solubility are compatible, 3.0 to 27.0 mol% is preferred, and 10.0 to 25.0 mol% is more preferred.

[0101] Diamine component

[0102] The diamine component contains compound A.

[0103] Among the diamine components, the content of compound A is 15.0 to 80.0 mol%, preferably 20.0 to 60.0 mol%, and more preferably 22.0 to 55.0 mol%, for the reason that strength and solubility are compatible.

[0104] The diamine component additionally contains 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0105] Among the diamine components, the content of BAPP is 15.0 to 80.0 mol%, 20.0 to 60.0 mol% is preferred, and 23.0 to 55.0 mol% is more preferred, for the reason that strength and solubility are compatible.

[0106] The diamine component additionally contains 4,4'-oxydianiline (ODA) and / or 3,4'-oxydianiline (DAPE).

[0107] Among the diamine components, the total content of ODA and DAPE is greater than 0.0 mol% and less than 30.0 mol%, preferably 5.0 to 28.0 mol%, and more preferably 10.0 to 27.0 mol%, for the reason that strength and solubility are compatible.

[0108] [Method for manufacturing polyimide and polyimide solution]

[0109] Next, a method for manufacturing the polyimide of the first to sixth embodiments described above (hereinafter, for convenience, also referred to as the “manufacturing method”) will be explained.

[0110] The following description also describes a solution of polyimide dissolved in a solvent (polyimide solution). The polyimide solution is also a coating material containing polyimide.

[0111] Polyimide solutions (coating materials) can be used as electrodeposition paints, insulating paints, heat-resistant paints, etc.

[0112] The present manufacturing method is, in principle, a method of obtaining the aforementioned polyimide (1st to 6th embodiments) by polymerizing (dehydrating condensation) the aforementioned diamine component and acid component in a solvent.

[0113] The diamine component is as described above.

[0114] As for the diamine component, additionally, aromatic diamines such as 1,4-phenylenediamine; aliphatic diamines such as 1,2-diaminoethane, 1,3-diaminopropane, 1,5-diaminopentane, 1,6-hexanediamine; generally known polyvalent amines; etc. may be used. These may be used alone or in combination of two or more types.

[0115] The acid components are as described above.

[0116] As for the acid component, additionally, aromatic tetracarboxylic acid dihydrides such as 4,4'-oxydiphthalic acid dihydride (ODPA) and 3,3',4,4'-benzophenone tetracarboxylic acid dihydride (BTDA); aliphatic tetracarboxylic acid dihydrides such as cyclohexane tetracarboxylic acid dihydride; etc. These may be used as a single type or as a combination of two or more types.

[0117] A diamine component and an acid component, blended in an appropriate molar ratio, are reacted in a solvent to obtain a polyamide acid. That is, a solution containing polyamide acid (a polyamide acid solution) is obtained.

[0118] At this time, the reaction temperature is preferably 30 to 70°C, and more preferably 40 to 60°C. The reaction time is preferably 1 to 36 hours, and more preferably 6 to 30 hours. The reaction is carried out, for example, under atmospheric pressure.

[0119] Next, the polyamide acid is imidized (dehydrated and cyclized) by heating the polyamide acid solution. Accordingly, a solution containing polyimide (polyimide solution) is obtained.

[0120] The temperature (heating temperature) when heating the polyamide acid (polyamide acid solution) is not particularly limited as long as a temperature is selected that allows the azeotropic solvent to be removed by distillation, but 140 to 220°C is preferred, and 160 to 200°C is more preferred.

[0121] The retention time (heating time) at this heating temperature is preferably 0.5 to 10 hours, and more preferably 2 to 7 hours. In addition, temperature control may be performed in an inert gas blowing environment or a reduced pressure environment as needed.

[0122] In the present manufacturing method, it is preferable to use a vessel equipped with various cooling devices, such as a Dean Stark type trap or a condenser. Afterwards, it is desirable to obtain a desired polyimide solution while removing moisture generated as the imidization progresses.

[0123] The molar ratio of the acid component to the diamine component (acid component / diamine component) may be arbitrarily set according to, for example, the viscosity of the polyimide solution used for coating, and is preferably 0.90 to 1.10, and more preferably 0.95 to 1.05.

[0124] The molecular structure of polyimide is not particularly limited. For example, depending on the polymerization conditions, random copolymers, alternating copolymers, block copolymers, etc., can be exemplified.

[0125] The weight-average molecular weight of the obtained polyimide is preferably 1,500 or higher. When the molecular weight is within this range, the polyimide solution exhibits sufficient viscosity, and it is easy to obtain the desired film thickness.

[0126] Meanwhile, the molecular weight is preferably 200,000 or less. If the molecular weight is within this range, problems with the stirring equipment are suppressed. In addition, it is easy to efficiently remove the solvent.

[0127] As a solvent used in the present manufacturing method, it is preferable to use a polar organic solvent because the resulting polyimide exhibits sufficient solubility.

[0128] When obtaining polyimide in a solvent, water generated by imidation is removed. Therefore, it is preferable to remove it by heating, etc., by coexisting with a known auxiliary solvent (e.g., benzene, toluene, xylene, etc.) that is known to have an azeotropic reaction with water.

[0129] In addition, it is desirable that the polyimide solution has fluidity corresponding to a coating and is a uniform, transparent solution free of precipitates.

[0130] In this regard, as a polar organic solvent, amide-based solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred.

[0131] The solid content of the polyimide solution is not particularly limited and is appropriately set according to the desired viscosity, etc., for example, 5 to 50 mass%.

[0132] The viscosity of the polyimide solution can be appropriately set within a range where no problems occur during coating, such as by stirring and mixing the polyimide solution or pumping it. Specifically, the viscosity at 25°C is preferably 0.3 to 200 Pa·s.

[0133] In the present manufacturing method, a dehydrating agent and an imidation catalyst may be combined in the solvent to promote imidation.

[0134] As for the dehydrating agent, any commonly known one may be used, for example, acid anhydrides such as acetic anhydride and oxalic anhydride; γ-valerolactone; etc.

[0135] As an imidation catalyst, any generally known catalyst may be used, for example, tertiary amines such as isoquinoline, β-picoline, and pyridine.

[0136] Dehydrating agents or imidization catalysts may be used in a mixture of multiple types.

[0137] In addition, crosslinking agents, coupling agents, etc. may be incorporated for the purpose of modifying the main chain of the polyimide to impart various properties, within a range that does not impair the mechanical and electrical properties of the obtained polyimide.

[0138] As for the crosslinking agent, any commonly known agent may be used, for example, oxazolines, melamines, isocyanates, aziridines, benzoxazines, bismaleimides, etc., and a mixture of multiple types may also be used.

[0139] From the perspective of industrial use, it is desirable for the polyimide solution to maintain its state after polymerization (dehydration condensation) for at least two weeks, and it is even more desirable that it does not involve a change in viscosity.

[0140] For this reason, a viscosity stabilizer may be added within a range that does not impair the mechanical and electrical properties of the resulting polyimide.

[0141] [Polyimide film (molding material)]

[0142] Next, a cured film (polyimide film) obtained using a polyimide solution will be explained.

[0143] Polyimide films are molding materials containing polyimide, and depending on their thickness, they can be processed into films, sheets, panels, etc. They may also be applied to seamless tubular tubes, belts, or molded parts using die molds.

[0144] Polyimide films can be used, for example, as heat-resistant molding materials in fields such as flexible printed circuit boards (FPC), chip-on-film (COF), and electronic circuit boards for tape-automated bonding (TAB).

[0145] The conditions for obtaining a polyimide film from a polyimide solution may vary depending on the composition of the polyimide, the type of solvent, the substrate to be coated, etc., but known methods may be employed as the method and are not particularly limited.

[0146] For example, a polyimide film, which is a cured film, is obtained by coating a polyimide solution onto a substrate and then drying it.

[0147] It is desirable that the substrate not be eroded by the solvent of the polyimide solution.

[0148] Specifically, the materials of the substrate may include, for example, glass; wood; stone; resins such as triacetate cellulose (TAC), polyethylene terephthalate (PET), diacetylcellulose, acetate butyrate cellulose, polyethersulfone, acrylic resin, polyurethane resin, polyester, polycarbonate, polysulfone, polyether, trimethylpentene, polyetherketone, (meth)acrylonitrile; rubber; metals such as SUS and copper; etc.

[0149] If the substrate has excellent transparency, the composite of the substrate and the cured film can be used as a transparent material.

[0150] If the substrate is colored, it can be used without damaging the design of the substrate.

[0151] As for the coating method, it is acceptable to use any method that is generally known, for example, roll coating, gravure coating, slide coating, spraying, immersion, screen printing, spraying, etc., appropriately.

[0152] As for the drying method, any generally known method may be used. Examples include hot air drying, far-infrared heating furnaces, ceramic heaters, muffle furnaces, etc., and a combination of multiple methods may also be used.

[0153] The drying temperature is set, for example, according to the boiling point of the solvent. It is also advisable to set it considering the glass transition point of the polyimide or the substrate.

[0154] In the polyimide solution obtained by the aforementioned manufacturing method, the imimide ring-closing process proceeds due to the heating of the solvent in the manufacturing method. Therefore, to form a cured film, it is sufficient to simply volatilize and remove the solvent after coating the polyimide solution. By appropriately setting the time and pressure, a cured film can be obtained even under conditions below the boiling point of the solvent.

[0155] The resulting cured polyimide film does not undergo the dehydration condensation process required for conventional polyimides, and therefore does not exhibit the curing shrinkage characteristic of polyimides.

[0156] For this reason, processes required for conventional polyimide, such as fixing and stretching the ends of the intermediate film, can be omitted.

[0157] In obtaining a polyimide film from a polyimide solution, a filler may be added to the polyimide solution for the purpose of improving various properties of the cured film.

[0158] As for the filler, any commonly known material may be used. Examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, carbon black, etc., and a mixture of multiple types may also be used. In addition, conductive components, coloring components, adhesion-imparting components, etc. may coexist among these.

[0159] In addition, known additives such as release agents, defoaming agents, leveling agents, ion trappers, polymerization inhibitors, antioxidants, viscosity modifiers, and antistatic agents may be added as needed.

[0160] The polyimide film can be used for the purposes of conventionally known polyimides.

[0161] For example, it is used in electronic devices such as displays, touch panels, projectors, printers, earphones, speakers, and antennas. The material may be selected on the premise of being installed in these electronic devices.

[0162] The obtained polyimide can be applied and used as a binder, for example, carbon fibers, glass fibers, metal nanowires, etc., as it has excellent physical properties such as heat resistance and hardness in addition to good mechanical properties.

[0163] Since the heating load can be reduced, it can be applied to electrodes of secondary batteries in which the substrate is made of metal foil.

[0164] Since it does not involve curing shrinkage and maintains dimensional stability, it can be applied to porous materials with internal voids. The polyimide film can be formed into a tube shape and used as tubes or belts.

[0165] A polyimide film obtained by ensuring film thickness precision, coating smoothly, and drying can be handled as a film, sheet, panel, etc. after peeling.

[0166] Since polyimide films can be expected to have sufficient durability against low-polarity solvents or moisture, they can be used in applications requiring water resistance or chemical resistance.

[0167] In addition, by applying this property, polyimide can be precipitated while mixing with a non-solvent such as alcohol, and, if necessary, washed or dried to obtain a solid polyimide (powder).

[0168] Examples

[0169] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below.

[0170] <Example 1>

[0171] Preparation of Polyimide Solution

[0172] Under a nitrogen atmosphere, 78.77 g of N-methyl-2-pyrrolidone (NMP) was mixed with 7.62 g (27.00 mmol) of 4,4'-methylenebis(2-ethyl-6-methylaniline) (MED) as compound A, 3.70 g (9.01 mmol) of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP), and 10.60 g (36.01 mmol) of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA). The mixture was stirred and reacted for 24 hours at 50°C and atmospheric pressure to obtain a polyamide acid solution.

[0173] γ-valerolactone (GVL), pyridine, and toluene were added to the obtained polyamide acid solution, and heated and stirred at 170°C for 5 hours while removing condensed water from the system to obtain a polyimide solution. The obtained polyimide solution was reddish-brown transparent.

[0174] Solubility

[0175] The obtained polyimide solution was left at room temperature and atmospheric pressure for two weeks. If good solubility and fluidity were observed after leaving it, "Good" was indicated in Table 1 below; if abnormalities such as gelation or precipitation occurred immediately after synthesis or within one day after synthesis, "Bad" was indicated. If "Good" is indicated, the polyimide in the obtained polyimide solution can be evaluated as having excellent solubility in a solvent.

[0176] Fabrication of Polyimide Films

[0177] 15g of the obtained polyimide solution (within 1 day of synthesis) was applied to a glass plate using a bar coater, and heated at 100°C for 30 minutes, at 150°C for 30 minutes, at 200°C for 90 minutes, and at 220°C for 30 minutes to obtain a polyimide film with a thickness of about 50㎛.

[0178] Machine Robbery

[0179] For the obtained polyimide film, a tensile test was performed under the following conditions in accordance with JIS K 7127:1999 (ISO 527-3:1995), and the tensile modulus (unit: GPa) and tensile strength (unit: MPa) were determined. The results are shown in Table 1 below.

[0180] Measuring device: AGS-J manufactured by Shimadzu Seisakusho

[0181] Tensile speed: 102 mm / min

[0182] Interval: 30mm

[0183] Thermal properties

[0184] For the obtained polyimide film, tests were conducted under the following conditions, and the glass transition temperature (unit: °C), coefficient of linear thermal expansion (unit: ppm / K), and thermal decomposition temperature (unit: °C) were determined. The results are shown in Table 1 below.

[0185] (Glass transition temperature)

[0186] Device: TA Instruments Manufactured DMA Q800

[0187] Heating rate: 3℃ / min

[0188] Temperature range: 50–450℃

[0189] Frequency: 1 Hz

[0190] (Linear thermal expansion coefficient)

[0191] Device: Shimazu Seisakusho TMA-60

[0192] Temperature range: 50℃-200℃

[0193] Heating rate: 10℃ / min

[0194] (Thermal decomposition temperature)

[0195] Device: Shimazu Seisakusho DTG-60

[0196] Speed: 10℃ / min

[0197] Thermal decomposition temperature: The temperature at which a 5 mass% decrease occurs from the measurement chart.

[0198] <Examples 2–25 and Comparative Examples 1–7>

[0199] The diamine component and acid component shown in Table 1 below were used in the amounts shown in Table 1 below, and a polyimide solution was prepared and evaluated in the same order as in Example 1. The results are shown in Table 1 below.

[0200] For Examples 12 and 19, polyimide films were prepared under the same conditions as in "Preparation of Polyimide Films" using samples stored at room temperature for two months after preparation, and mechanical strength and thermal properties were measured. The results are shown in Table 2 below. Even after two months of storage, results almost identical to those obtained immediately after synthesis were obtained.

[0201] In addition, for samples in which solubility was "Bad" (specifically, Comparative Examples 1 to 7), a polyamide acid solution was prepared again. It was confirmed that there was no gelation or precipitation in any of the samples. Using the obtained polyamide acid solution, a polyimide film was prepared under the same conditions as in "Preparation of Polyimide Film," and mechanical strength and thermal properties were measured for reference.

[0202] Each component shown in Table 1 below is as follows.

[0203] BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride represented by the following formula (1)

[0204] PMDA: Pyromellitic acid dihydrogen represented by the following formula (2)

[0205] MED: 4,4'-methylenebis(2-ethyl-6-methylaniline) represented by the following formula (3)

[0206] MMD: 4,4'-methylenebis(2,6-dimethylaniline) represented by the following formula (4)

[0207] EED: 4,4'-methylenebis(2,6-diethylaniline) represented by the following formula (5)

[0208] MDA: 4,4'-methylenedianiline represented by the following formula (6)

[0209] BAPP: 2,2-bis-[4-(4-aminophenoxy)phenyl]propane represented by the following formula (7)

[0210] DAT: 2,4-diaminotoluene represented by the following formula (8)

[0211] ODA: 4,4'-oxydianiline represented by the following formula (9)

[0212] DAPE: 3,4'-oxydianiline represented by the following formula (10)

[0213]

[0214]

[0215]

[0216]

[0217]

[0218]

[0219]

[0220] <Summary of Evaluation Results>

[0221] As shown in Table 1 above, the polyimides of Examples 1 to 25 had good solubility in solvents.

[0222] In this regard, the polyimides of Comparative Examples 1 to 7 had insufficient solubility in solvents.

Claims

Claim 1 A polyimide formed by polymerizing an acid component consisting of 3,3',4,4'-biphenyltetracarboxylic acid dihydride, 20.0 to 80.0 mol% of compound A represented by the following formula (A), and 20.0 to 80.0 mol% of a diamine component containing 2,2-bis-[4-(4-aminophenoxy)phenyl]propane. R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group. Claim 2 A polyimide formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, 20.0 to 80.0 mol% of compound A represented by the following formula (A), and 20.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane. R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group. Claim 3 A polyimide formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride, 15.0 to 80.0 mol% of compound A represented by the following formula (A), 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and a diamine component containing more than 0.0 mol% and less than 30.0 mol% of 2,4-diaminotoluene. R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group. Claim 4 A polyimide formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 15.0 to 80.0 mol% of compound A represented by the following formula (A), 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane and more than 0.0 mol% and less than 30.0 mol% of 2,4-diaminotoluene. R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group. Claim 5 A polyimide formed by polymerizing an acid component containing 3,3',4,4'-biphenyltetracarboxylic acid dihydride, 15.0–80.0 mol% of compound A represented by the following formula (A), 15.0–80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and a diamine component containing more than 0.0 mol% and less than 30.0 mol% of 4,4'-oxydianiline and / or 3,4'-oxydianiline. R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group. Claim 6 A polyimide formed by polymerizing an acid component containing more than 70.0 mol% and less than 100.0 mol% of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and more than 0.0 mol% and less than 30.0 mol% of pyromellitic acid dianhydride, and a diamine component containing 15.0 to 80.0 mol% of compound A represented by the following formula (A), 15.0 to 80.0 mol% of 2,2-bis-[4-(4-aminophenoxy)phenyl]propane, and more than 0.0 mol% and less than 30.0 mol% of 4,4'-oxydianiline and / or 3,4'-oxydianiline. R in the above formula (A) 1 , R 2 , R 3 and R 4 Each is independently a methyl group or an ethyl group. Claim 7 A polyimide solution containing 5 to 50 mass% of the polyimide described in any one of claims 1 to 6 in a polar organic solvent. Claim 8 A coating material containing a polyimide as described in any one of claims 1 to 6. Claim 9 A molding material containing a polyimide as described in any one of paragraphs 1 to 6.

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