Polyamic acid, polyamic acid solution, polyimide, polyimide substrate and laminate, and methods for producing the same.

Abstract

The purpose of the present invention is to provide: a polyimide which exhibits high heat resistance and high transparency and which exhibits improved adhesion to inorganic films; a poly(amic acid) that is a precursor of the polyimide; a polyimide substrate and a layered product; and methods for producing these.　The foregoing can be achieved by: a poly(amic acid) which is a product of a polyaddition reaction between a diamine and a tetracarboxylic acid dianhydride, wherein the diamine includes 1,4-phenylenediamine and 1,3-bis(3-aminopropyl)tetramethyldisiloxane and the tetracarboxylic acid dianhydride includes 3,3,4,4-biphenyltetracarboxylic acid dianhydride and 9,9-bis(3,4-dicarboxyphenyl)fluorene acid dianhydride; and a polyimide and a polyimide substrate obtained from the poly(amic acid).

Description

Technical Field

[0001] The present invention relates to polyamic acid, polyamic acid solution, polyimide, polyimide substrate, laminate, and methods for producing them.

Background Art

[0002] In electronic devices such as displays, touch panels, and solar cells, thinning, weight reduction, and flexibility are required, and resin film substrates are used instead of glass substrates.

[0003] In these devices, various electronic elements such as thin film transistors and transparent electrodes are formed on the substrate, and a high-temperature process is required for the formation of these electronic elements. General aromatic polyimides have sufficient heat resistance to withstand high-temperature processes, and their linear thermal expansion coefficient (CTE) is also close to that of glass substrates and electronic elements, making it difficult for internal stress to occur. Therefore, they are suitable as substrate materials for flexible displays and the like.

[0004] Generally, aromatic polyimides are colored yellowish-brown due to intramolecular conjugation and the formation of charge transfer (CT) complexes. In top emission type organic ELs and the like, since light is extracted from the side opposite to the substrate side, transparency is not required for the substrate, so general aromatic polyimides have been used. However, in cases where light emitted from the display element is emitted through the substrate, such as in transparent displays, bottom emission type organic ELs, and liquid crystal displays, and when sensors and camera modules are arranged on the back surface of the substrate in order to make a smartphone etc. a full-screen display (notchless), high optical properties are also required for the substrate.

[0005] From such a background, there is a demand for a material having heat resistance equivalent to that of existing aromatic polyimides and further excellent transparency.

[0006] It has been reported that the formation of CT complexes can be suppressed by using aliphatic monomers to reduce the coloration of polyimides (Patent Documents 1 and 2). In addition, although not relating to a technique for reducing the coloration of polyimides, it is known that the polyimide film obtained by adding silicone oil to polyamic acid as a polyimide precursor and performing imidization exhibits high adhesion to the substrate (Patent Document 3). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2012-041530 [Patent Document 2] Japanese Patent No. 5660249 [Patent Document 3] Japanese Patent Application Publication No. 2015-229691 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the above-mentioned conventional technologies still have room for improvement in terms of high heat resistance and excellent transparency. The polyimides described in Patent Documents 1 and 2 have high transparency and low CTE, but because they have an aliphatic structure, their thermal decomposition temperature is low and they are not suitable for high-temperature processes for forming electronic devices.

[0009] Furthermore, organic EL light-emitting elements have low moisture resistance, and moisture entering from the outside can cause dark spots, leakage currents, and failure to light up. When resin is used as the substrate, it is not possible to completely block out moisture. Therefore, in order to improve the barrier properties of the substrate, inorganic films such as silicon oxide films and silicon nitride films are used as intermediate layers between each polyimide layer in a two-layer polyimide film, or on top of the two-layer polyimide film. However, inorganic films have low adhesion to polyimide films, and there is a problem that delamination or lifting occurs at the interface between the inorganic film and the polyimide film during the process.

[0010] In view of the above, the present invention aims to provide a polyimide having high heat resistance and high transparency, and further improved adhesion to inorganic films, as well as a polyamic acid as a precursor thereof, a polyimide substrate and laminate, and methods for producing the same. [Means for solving the problem]

[0011] The inventors of this application have found that by introducing a rigid structure into the polymer backbone and further using a monomer component having a siloxane bond, a polyimide satisfying the above properties and a polyamic acid as its precursor can be obtained. One embodiment of this invention has the following configuration.

[0012] A polyamic acid obtained as a polyaddition reaction product of a diamine and a tetracarboxylic dianhydride, wherein the diamine comprises 1,4-phenylenediamine and 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and the tetracarboxylic dianhydride comprises 3,3,4,4-biphenyltetracarboxylic dianhydride and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride. [Effects of the Invention]

[0013] The present invention provides a polyimide having high heat resistance and high transparency, as well as improved adhesion to inorganic films, and a polyamic acid as a precursor thereof. These are suitable as substrate materials for electronic devices. [Modes for carrying out the invention]

[0014] A polyamic acid according to one embodiment of the present invention is a polyamic acid obtained as a polyaddition reaction product of a diamine and a tetracarboxylic dianhydride, wherein the diamine comprises 1,4-phenylenediamine and 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and the tetracarboxylic dianhydride comprises 3,3,4,4-biphenyltetracarboxylic dianhydride and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride.

[0015] The polyimide obtained from the polyamic acid according to this embodiment has siloxane bonds in the resin, which increases its affinity for inorganic films (e.g., silicon oxide films) and is expected to improve adhesion to inorganic films. On the other hand, if the repeating units of siloxane bonds become long, the glass transition temperature (Tg) of the resin may decrease significantly, heat resistance may decrease due to the generation of cyclic siloxanes by intramolecular condensation, and equipment may become contaminated. Therefore, it is preferable to have small repeating units of siloxane bonds. Specifically, by using 1,3-bis(3-aminopropyl)tetramethyldisiloxane, a polyimide with high adhesion to inorganic films and high heat resistance can be obtained. From the viewpoint of achieving both adhesion and heat resistance, the proportion of 1,3-bis(3-aminopropyl)tetramethyldisiloxane when the total diamines are set to 100 mol% is preferably 0.1 mol% to 10.0 mol%, more preferably 0.15 mol% to 1.0%, and even more preferably 0.2 mol% to 0.5 mol%. By setting the range as described above, the polyimide obtained from the polyamic acid can have sufficient adhesion to inorganic films (e.g., silicon oxide films) and heat resistance that can withstand high-temperature processes.

[0016] To obtain a polyimide with low internal stress, the polyamic acid is preferably a polyamic acid in which the proportion of 3,3,4,4-biphenyltetracarboxylic dianhydride is 70 mol% to 99 mol%, more preferably 75 mol% to 98 mol%, more preferably 75 mol% to 97 mol%, more preferably 75 mol% to 96 mol%, more preferably 75 mol% to 95 mol%, and even more preferably 80 mol% to 90 mol%.

[0017] 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride, due to its bulky structure, suppresses the formation of charge transfer complexes, and is therefore effective in achieving transparency in the polyimide obtained from the polyamic acid. On the other hand, this bulky structure inhibits molecular chain packing, so the internal stress of the polyimide obtained from the polyamic acid tends to increase. Therefore, from the viewpoint of achieving both transparency and appropriate internal stress, the polyamic acid is preferably one in which the proportion of 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride is 1 mol% to 30 mol%, more preferably 5 mol% to 25 mol%, and even more preferably 10 mol% to 20 mol%, when the total amount of tetracarboxylic dianhydrides is set to 100 mol%. By setting the proportion within the above range, the increase in internal stress of the polyimide obtained from the polyamic acid is suppressed, and the internal stress generated when laminated with a glass substrate or the like can be reduced. Therefore, a material with excellent process compatibility can be obtained in the manufacturing process of a laminate using polyimide obtained from the polyamic acid, or an electronic device using the laminate, without the laminate warping.

[0018] The polyamic acid according to this embodiment may be other than 1,4-phenylenediamine and may also contain other diamine components other than 1,3-bis(3-aminopropyl)tetramethyldisiloxane, as long as its performance is not impaired. Examples of the other diamine components mentioned above include 1,4-diaminocyclohexane, 1,3-phenylenediamine, 4,4'-oxydianiline, 3,4'-oxydianiline, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-diaminodiphenylsulfone, 4-(aminophenyl)4-aminobenzoate, m-tolidine, o-tolidine, 4,4'-bis(aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'dihydroxybiphenyl, 4,4'-methylenebis(cyclohexaneamine), and analogues thereof. These may be used individually or in combination of two or more types. Among these, 4-(aminophenyl)4-aminobenzoate is desirable in terms of improving Tg and transparency.

[0019] The polyamic acid according to this embodiment may be other than 3,3,4,4-biphenyltetracarboxylic acid dianhydride and may also contain other acid dianhydride components other than 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride, as long as its performance is not impaired. Other acid dianhydride components include, for example, pyromellitic acid dianhydride, 1,4-phenylenebis(trimellitate acid dianhydride), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4'-oxyphthalic acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic acid dianhydride, and 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride. Examples include hydrates, cyclobutanetetracarboxylic dianhydrides, 2'-oxodispiro[bicylco[2.2.1]heptane-2,1'-cyclopentane-3',2''-bicylco[2.2.1]heptane]-5,6:5'',6''-tetracarboxylic dianhydrides, and their analogs, and these may be used alone or in combination of two or more.

[0020] [Synthesis of Polyamic Acid and Polyimide] The polyimide containing the above structure can be obtained by a known method. The polyimide can be synthesized by a synthesis method via precursors such as polyamic acid and polyimide ester, and a synthesis method without passing through a precursor. From the availability of monomers and the simplicity of polymerization, it is preferable to synthesize polyimide by imidization of polyamic acid as a precursor.

[0021] The polyamic acid containing the above structure can be obtained by reacting diamine with tetracarboxylic dianhydride in an organic solvent. For example, the diamine may be dissolved or dispersed in a slurry state in an organic solvent to form a diamine solution, and the tetracarboxylic dianhydride may be added to the above diamine solution in a solution or solid state dissolved or dispersed in an organic solvent. The diamine may be added to the tetracarboxylic dianhydride solution. The dissolution and reaction of the diamine and tetracarboxylic dianhydride are preferably carried out in an inert gas atmosphere such as argon or nitrogen.

[0022] In the synthesis of the polyamic acid, it is preferable to adjust the mole number of the total amount of the diamine component and the mole number of the total amount of the tetracarboxylic dianhydride component to be substantially equimolar. By using a plurality of types of diamines and / or a plurality of types of tetracarboxylic dianhydrides, a polyamic acid having a plurality of structural units can be obtained. Also, by blending polyamic acids having different structures, a blend of polyamic acids having a plurality of types of structural units with different structures can also be obtained.

[0023] The organic solvent used in the synthesis reaction of the polyamic acid is not particularly limited. The organic solvent is preferably one that can dissolve the tetracarboxylic dianhydride and diamines used and can also dissolve the polyamic acid produced by polymerization. Specific examples of the organic solvent include urea solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide or sulfone solvents such as dimethyl sulfoxide, diphenyl sulfone, and tetramethyl sulfone; amide solvents such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N'-diethylacetamide, and N-methyl-2-pyrrolidone (NMP); ester solvents such as γ-butyrolactone; amide solvents such as hexamethylphosphoric triamide; alkyl halide solvents such as chloroform and methylene chloride; aromatic hydrocarbon solvents such as benzene and toluene; phenol solvents such as phenol and cresol; ketone solvents such as cyclopentanone; and ether solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. Two or more organic solvents may be used in combination as necessary. In order to enhance the solubility and reactivity of the polyamic acid, the organic solvent used in the synthesis of the polyamic acid is preferably selected from amide solvents, ketone solvents, ester solvents, and ether solvents, and particularly preferably amide solvents such as DMF, DMAC, and NMP.

[0024] The temperature conditions for the synthesis reaction of the polyamic acid are not particularly limited. From the perspective of suppressing the decrease in the molecular weight of the polyamic acid due to depolymerization, the reaction temperature is preferably 80°C or lower. From the perspective of allowing the polymerization reaction to proceed moderately, the reaction temperature is more preferably 0 to 50°C. The reaction time can be arbitrarily set within the range of 10 minutes to 30 hours.

[0025] By polymerizing the diamine and the tetracarboxylic dianhydride in the aforementioned organic solvent, a polyamic acid solution containing polyamic acid and an organic solvent is obtained. This polymerization solution can be used as is as a polyamic acid solution. The concentration of polyamic acid and the viscosity of the solution may be adjusted by removing part of the solvent from the polymerization solution or by adding a solvent. The solvent added may be different from the solvent used for polymerization of the polyamic acid. Alternatively, a polyamic acid solution may be prepared by dissolving the solid polyamic acid resin obtained by removing the solvent from the polymerization solution in a solvent. As the organic solvent for the polyamic acid solution, one with high solubility of polyamic acid is preferred, and the organic solvents exemplified above can be used as the organic solvent for the synthesis of polyamic acid. Among these, amide solvents such as DMF, DMAC, and NMP are preferred.

[0026] Imidation is carried out by dehydration and cyclization of the polyamic acid. Dehydration and cyclization are carried out by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. When imidation is carried out in solution, it is preferable to add an imidating agent and / or a dehydration catalyst to the polyamic acid solution to carry out chemical imidation. The imidating agent is not particularly limited, but it is preferable to use a tertiary amine, and among these, a heterocyclic tertiary amine is more preferable. Examples of heterocyclic tertiary amines include pyridine, picoline, quinoline, isoquinoline, and imidazoles. Examples of dehydration catalysts include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and γ-valerolactone.

[0027] When removing the solvent from the polyamic acid solution to perform imidation, thermal imidation, which involves dehydration and ring closure by heating, is preferred. The method of heating the polyamic acid is not particularly limited, but for example, the polyamic acid solution may be applied to a support such as a glass plate, metal plate, or PET (polyethylene terephthalate), and then heat-treated in the range of 80°C to 500°C. The heating time varies depending on the amount of polyamic acid solution to be dehydrated and ring-closure and the heating temperature, but generally, it is preferable to heat for 1 minute to 5 hours after the processing temperature reaches the maximum temperature. An imidizing agent and / or a dehydration catalyst may be added to the polyamic acid solution, and imidation may be performed by heating in the manner described above.

[0028] When the polyamic acid is thermally imidated, the imidation reaction and the decomposition of the polyamic acid occur simultaneously. By suppressing the decomposition of the polyamic acid, the formation of end groups can be reduced, and a polyimide film with excellent transparency can be obtained. Methods for suppressing the decomposition of the polyamic acid include esterification, silyl esterification, and increasing the reaction rate, but any method may be used. Specifically, by adding a small amount of tertiary amine such as imidazoles, the imidation rate during thermal imidation can be accelerated, and a polyimide film with excellent transparency can be obtained. Examples of the imidazoles include 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-phenylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. Among these, 1,2-dimethylimidazole is preferred.

[0029] The imidazole content in the polyamic acid solution is preferably 0.005 mol to 0.100 mol, more preferably 0.010 mol to 0.080 mol, and even more preferably 0.015 mol to 0.050 mol per 1.000 mol of amide groups of polyamic acid. "Amid groups of polyamic acid" refers to amide groups produced by the polyaddition reaction of a diamine and a tetracarboxylic dianhydride. If the amount of imidazole added is within the above range, improved transparency and low internal stress of the polyimide film can be expected.

[0030] When adding the imidazoles, it is preferable to add them after polymerization of the polyamic acid. The imidazoles may be added directly to the polyamic acid solution, or they may be added to the polyamic acid solution as an imidazole solution.

[0031] The imidation from polyamic acid to polyimide can be carried out at any imidation rate from 1% to 100%, and a partially imidized polyamic acid may be synthesized. As imidation from polyamic acid to polyimide proceeds, the solubility in organic solvents and the viscosity of the solution tend to change. Furthermore, it is generally not easy to stop the imidation at a specific imidation rate. When forming a film by coating and drying the solution, the viscosity and thixotropy of the solution affect the uniformity of the film thickness. Therefore, considering the stability of the process, it is preferable to coat the polyamic acid solution onto a support with an imidation rate of 0% without adding an imidating agent and a dehydration catalyst to the polyamic acid, and then remove the solvent and perform imidation by heating on the support.

[0032] [Uses of polyamic acids and polyimides] The polyamic acid and polyimide according to one embodiment of the present invention may be used as is in the manufacture of products and components. Alternatively, a composition may be formed by adding a thermosetting component, a photocurable component, a nonpolymerizable binder resin, a dye, a surfactant, a leveling agent, a plasticizer, a silane coupling agent, fine particles, a sensitizer, etc. to the polyamic acid and polyimide. The blending ratio of these optional components is preferably in the range of 0.1% to 95% by weight relative to the total solid content of the polyimide. The solid content of the composition includes all components other than organic solvents, and liquid monomer components are also included in the solid content.

[0033] The polyimide according to one embodiment of the present invention has excellent transparency and heat resistance, and can therefore be used as a transparent substrate for glass substitute applications, etc., and is expected to be applied to substrates for electronic devices such as TFT substrates and electrode substrates. Among the electronic devices, it is preferable to use it as a substrate for devices that require light transmittance, such as liquid crystal display devices, organic EL elements, electronic paper, and touch panels. The polyimide according to one embodiment of the present invention can also be used as an optical component such as a color filter, anti-reflective film, or hologram, as well as a building material and a structural material. Various inorganic thin films, such as metal oxides and transparent electrodes, may be formed on the surface of the polyimide according to one embodiment of the present invention. The inorganic thin film can be formed, for example, by PVD methods such as sputtering, vacuum deposition, and ion plating, and dry processes such as CVD.

[0034] [Fabrication of polyimide substrates and electronic devices] The polyimide according to one embodiment of the present invention is preferably used as a substrate for electronic devices manufactured by a batch process because, in addition to its heat resistance and transparency, it has good adhesion to a support. In a batch process, an electronic device is obtained by forming a polyimide film (substrate) on a support, forming electrodes and / or electronic elements thereon, and then peeling the polyimide substrate on which the electrodes and / or electronic elements are formed from the support.

[0035] Accordingly, the embodiment of the present invention also includes a polyimide substrate made of the aforementioned polyimide, a laminate of the polyimide substrate and a support, and an electronic device comprising electrodes and / or electronic elements on the aforementioned polyimide substrate. Furthermore, the embodiment of the present invention also includes a method for manufacturing a laminate of a polyimide substrate and a support, wherein the polyimide substrate is formed on the support by casting the polyamic acid solution onto the support and imidizing it.

[0036] The thickness of the polyimide substrate is approximately 1 to 200 μm, and preferably approximately 5 to 100 μm.

[0037] In one embodiment of the present invention, in order to enhance the barrier properties of the polyimide substrate, inorganic films such as silicon oxide films and silicon nitride films may be used as intermediate layers between each polyimide layer of the two-layered polyimide film, or on the films of the two-layered polyimide film.

[0038] As a specific example, the polyamic acid solution is applied to a support, dried by heating and imidized, and then an inorganic film is deposited by CVD onto the polyimide film formed on the support. Subsequently, the polyamic acid solution is applied again onto the inorganic film, dried by heating and imidized, thereby obtaining a polyimide film (polyimide substrate) that is tightly laminated on the support. This example is a polyimide substrate in which the inorganic film is used as an intermediate layer between each polyimide layer of a two-layer polyimide film.

[0039] Examples of supports to which the polyamic acid solution is applied include glass substrates (glass plates); metal substrates or metal belts such as SUS; and resin films such as polyethylene terephthalate, polycarbonate, polyacrylate, polyethylene naphthalate, and triacetylcellulose. To adapt to current batch-type device manufacturing processes, it is more preferable to use a glass substrate (glass plate) as the support.

[0040] When the polyamic acid solution is applied to a support such as glass and heated, the imidation of the polyamic acid begins as the solvent evaporates, and the organic solvent and water produced by imidation (dehydration of polyamic acid) volatilize from the polyamic acid solution. At this time, some of the water and / or organic solvent does not volatilize and remains between the support and the resin film undergoing imidation, causing delamination at the interface between the support and the resin film. The water and / or organic solvent that remains at the interface between the support and the resin film is then discharged through the polyimide film during the subsequent heating process at high temperatures, leaving bubbles in the areas where delamination or lifting has occurred. The presence of such bubbles causes problems when forming elements on the polyimide substrate. In particular, in thin or miniaturized devices, even fine delamination or lifting can have a significant impact on the formation or mounting of elements.

[0041] The polyamic acid and polyimide according to one embodiment of the present invention having a siloxane structure exhibit high adhesion not only to glass but also to inorganic films used as intermediate layers, etc. Therefore, during solvent drying and imidation on the support, lifting and delamination caused by the accumulation of organic solvents or water at the interface between the glass support and the resin film are less likely to occur. As a result, the formation and mounting of devices on a polyimide substrate tightly laminated on the support can be accurately carried out.

[0042] A polyimide film prepared using a polyamic acid solution according to one embodiment of the present invention can have high heat resistance, high transparency, and improved adhesion to inorganic films.

[0043] The polyimide film (polyimide substrate) closely laminated on the support preferably has a 90° peel strength from the support of 0.08 N / cm to 5.00 N / cm, more preferably 0.09 N / cm to 4.00 N / cm, and even more preferably 0.10 N / cm to 3.50 N / cm. When the polyimide film (polyimide substrate) closely laminated on the support has the above adhesion, delamination from the support is less likely to occur during the device formation and mounting process, and delamination from the support after the device formation and mounting is easy. The 90° peel strength can be measured by the method described in the examples below.

[0044] For applications such as displays, the transparency of the polyimide or polyimide film is required to be high in the entire wavelength range of visible light. The yellowness (YI) of the polyimide or polyimide film is preferably 20 or less, and more preferably 18 or less. YI can be measured according to JIS K7373-2006. A polyimide film with such high transparency can be used as a transparent substrate for glass substitute applications and the like.

[0045] The internal stress between the polyimide substrate and the support is preferably 30 MPa or less, preferably 25 MPa or less, and more preferably 20 MPa or less. The internal stress between the polyimide substrate and the support can be measured by the method described in the embodiments below. If the internal stress is 30 MPa or less, the laminate will not warp during the manufacturing process of the electronic device, and therefore the polyimide substrate has the advantage of being highly process compatible.

[0046] One embodiment of the present invention may have the following configuration:

[0047] 1) A polyamic acid obtained as a polyaddition reaction product of a diamine and a tetracarboxylic dianhydride, wherein the diamine comprises 1,4-phenylenediamine and 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and the tetracarboxylic dianhydride comprises 3,3,4,4-biphenyltetracarboxylic dianhydride and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride.

[0048] 2) The polyamic acid according to 1), wherein the proportion of 1,3-bis(3-aminopropyl)tetramethyldisiloxane to the total amount of the diamine is 0.1 mol% to 10.0 mol%.

[0049] 3) The polyamic acid according to 1) or 2), wherein the proportion of 3,3,4,4-biphenyltetracarboxylic dianhydride to the total amount of tetracarboxylic dianhydride is 70 mol% to 99 mol%.

[0050] 4) A polyamic acid solution containing the polyamic acid described in any one of items 1) to 3) and an organic solvent.

[0051] 5) A polyamic acid solution as described in 4), further containing imidazoles.

[0052] 6) The polyamic acid solution according to 5), wherein the content of the imidazoles is 0.10 mol or less per mol of amide groups of the polyamic acid.

[0053] 7) A polyimide that is an imidized product of a polyamic acid solution described in any of 4) to 6).

[0054] 8) The polyimide described in 7), wherein the yellowness (YI) at a film thickness of 10 μm is 20 or less.

[0055] 9) A method for manufacturing a laminate of a polyimide substrate and a support, comprising casting a polyamic acid solution described in any of 4) to 6) onto a support and imidizing it to form a polyimide substrate on the support.

[0056] 10) A laminate of a polyimide substrate made of the polyimide described in 7) or 8) and a support.

[0057] 11) The laminate according to 10), wherein the internal stress generated between the polyimide substrate and the support is 30 MPa or less.

[0058] 12) An electronic device comprising electrodes and / or electronic elements on a polyimide substrate as described in 10) or 11).

[0059] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Examples]

[0060] (Evaluation method) The material properties and other values ​​described herein were obtained by the following method.

[0061] (1) Peel strength The 90° peel strength was measured for laminates of a glass plate (alkali-free glass) and a polyimide film, and for laminates of a glass plate with a silicon oxide film (inorganic film) and a polyimide film, in accordance with the ASTM D1876-01 standard, from the glass plate and the glass plate with the silicon oxide film (inorganic film), respectively. A 10 mm wide cut was made in the polyimide film with a utility knife, and a 90° peel test was performed using a Toyo Seiki tensile testing machine (Strograph VES1D) at 23°C and 55% RH conditions, with a tensile speed of 50 mm / min and a peel length of 50 mm. The average value of the peel strength was defined as the peel strength.

[0062] Here, the laminate of the glass plate (alkali-free glass) and the polyimide film was prepared in the same manner as described later in [Preparation of Polyimide Film]. Furthermore, the laminate of the glass plate on which the silicon oxide film (inorganic film) was formed and the polyimide film was prepared in the same manner as described later in [Preparation of Polyimide Film], except that a glass plate on which the silicon oxide film (inorganic film) was formed was used as the glass plate. The glass plate on which the silicon oxide film (inorganic film) was formed was prepared by CVD deposition of the silicon oxide film onto the glass plate.

[0063] (2) Measurement of internal stress Polyamic acid solutions prepared in the examples and comparative examples were applied to Corning alkali-free glass (0.7 mm thick, 100 mm x 100 mm) whose warpage had been measured in advance, using a spin coater. The glass plate coated with the polyamic acid solution was fired in air at 120°C for 30 minutes and then in a nitrogen atmosphere at 430°C for 30 minutes to obtain a laminate of a glass substrate and a 10 μm thick polyimide film. The warpage of this laminate of glass substrate and polyimide film was measured using a Tencor FLX-2320-S thin-film stress analyzer, and the internal stress generated between the glass substrate and polyimide film at 25°C in a nitrogen atmosphere was evaluated. To avoid water absorption by the polyimide film, the laminate of glass substrate and polyimide film was measured immediately after firing or after drying at 120°C for 10 minutes.

[0064] (3) 1% weight loss temperature (TD1) Using a TG / DTA / 7200 manufactured by Hitachi High-Tech Science Co., Ltd., the polyimide film was heated from 25°C to 650°C at a rate of 20°C / min under an N2 atmosphere. Considering the effect of moisture, the weight of the polyimide film at 150°C was used as the baseline, and the temperature at which the weight decreased by 1% from that point was defined as the TD1 of the polyimide film.

[0065] (4) Yellowness (YI) of polyimide film Using a UV-Vis-Near-Infrared Spectrophotometer (V-650) manufactured by JASCO Corporation, the light transmittance of the polyimide film at 200-800 nm was measured, and the Yellow Index (YI) was calculated as an indicator of yellowness using the formula described in JIS K 7373.

[0066] (5) Appearance after heating test (high-temperature film deposition process stability) Polyamic acid solutions prepared in the examples and comparative examples were applied to Corning's alkali-free glass (0.7 mm thick, 100 mm x 100 mm) using a spin coater. The glass substrate coated with the polyamic acid solution was fired in air at 120°C for 30 minutes and then in a nitrogen atmosphere at 430°C for 30 minutes to obtain a laminate of the glass substrate and a 10 μm thick polyimide film. A 1 μm layer of SiOx was deposited on the polyimide film of this laminate using the PE-CVD method. The laminate was then fired in a nitrogen atmosphere by raising the temperature from room temperature to 470°C at a rate of 5°C / min and holding it for 10 minutes after reaching 470°C. After firing, the SiOx or the gap between the glass substrate and the polyimide film was visually inspected. No gaps were marked with ○ (good), one to five gaps with a deviation mark

[0067] [Preparation of polyamic acid solution] <Example 1> In a 300 mL glass separable flask equipped with a stirrer featuring stainless steel impellers and a nitrogen inlet tube, 8.68 g of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 2.55 g of 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride (BPAF), and 85.0 g of N-methyl-2-pyrrolidone (NMP) were charged and stirred at room temperature (23°C) until dissolved. After 30 minutes, 0.009 g of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (PAM-E) was added to the resulting solution and stirred further. To this solution, 3.76 g of 1,4-phenylenediamine (PDA) was added and stirred at room temperature for 5 hours to obtain a polyamic acid solution. The concentrations of the diamine and tetracarboxylic acid dianhydride in this reaction solution were 15% by weight relative to the total volume of the reaction solution. Furthermore, 1,2-dimethylimidazole (DMI) was added to this solution in a concentration of 1% by weight relative to the polyamic acid (resin component) and dissolved.

[0068] <Example 2> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.68g, the amount of BPAF added to 2.55g, the amount of PAM-E added to 0.013g, and the amount of PDA added to 3.76g.

[0069] <Example 3> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.68g, the amount of BPAF added to 2.55g, the amount of PAM-E added to 0.017g, and the amount of PDA added to 3.76g.

[0070] <Example 4> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.69 g, the amount of BPAF added to 2.55 g, the amount of PAM-E added to 0.026 g, and the amount of PDA added to 3.74 g.

[0071] <Example 5> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.68g, the amount of BPAF added to 2.55g, the amount of PAM-E added to 0.043g, and the amount of PDA added to 3.73g.

[0072] <Example 6> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.67g, the amount of BPAF added to 2.54g, the amount of PAM-E added to 0.086g, and the amount of PDA added to 3.70g.

[0073] <Example 7> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 10.085g, the amount of BPAF added to 0.993g, the amount of PAM-E added to 0.018g, and the amount of PDA added to 3.904g, and 1,2-dimethylimidazole was not added.

[0074] <Example 8> A polyamic acid solution was obtained in the same manner as in Example 7, except that the amount of BPDA added was changed to 9.370g, the amount of BPAF added to 1.784g, the amount of PAM-E added to 0.018g, and the amount of PDA added to 3.829g.

[0075] <Example 9> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 9.366g, the amount of BPAF added to 1.784g, the amount of PAM-E added to 0.026g, and the amount of PDA added to 3.823g.

[0076] <Example 10> A polyamic acid solution was obtained in the same manner as in Example 7, except that the amount of BPDA added was changed to 8.681 g, the amount of BPAF added to 2.546 g, the amount of PAM-E added to 0.017 g, and the amount of PDA added to 3.756 g.

[0077] <Example 11> A polyamic acid solution was obtained in the same manner as in Example 7, except that the amount of BPDA added was changed to 8.629 g, the amount of BPAF added to 2.551 g, the amount of PAM-E added to 0.043 g, and the amount of PDA added to 3.766 g.

[0078] <Example 12> A polyamic acid solution was obtained in the same manner as in Example 7, except that the amount of BPDA added was changed to 8.018 g, the amount of BPAF added to 3.279 g, the amount of PAM-E added to 0.017 g, and the amount of PDA added to 3.686 g.

[0079] <Example 13> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.015 g, the amount of BPAF added to 3.278 g, the amount of PAM-E added to 0.025 g, and the amount of PDA added to 3.681 g.

[0080] <Example 14> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 7.543g, the amount of BPAF added to 3.871g, the amount of PAM-E added to 0.025g, and the amount of PDA added to 3.651g.

[0081] <Example 15> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 8.587g, the amount of BPAF added to 2.549g, the amount of PAM-E added to 0.173g, and the amount of PDA added to 3.692g.

[0082] <Example 16> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 4.548g, the amount of BPAF added to 7.087g, the amount of PDA added to 3.342g, and the amount of PAM-E added to 0.023g.

[0083] <Comparative Example 1> In a 300 mL glass separable flask equipped with a stirrer featuring stainless steel impellers and a nitrogen inlet tube, 8.70 g of BPDA, 2.55 g of BPAF, and 85.0 g of NMP were charged and stirred at room temperature (23°C) until dissolved. After 30 minutes, 3.75 g of PDA was added to this solution and stirred at room temperature for 5 hours to obtain a polyamic acid solution. Further, 1,2-dimethylimidazole was added to this solution to a concentration of 1% by weight relative to the polyamic acid (resin component) and dissolved.

[0084] <Comparative Example 2> A polyamic acid solution was obtained in the same manner as in Comparative Example 1, except that the amount of BPDA added was changed to 9.478 g, the amount of BPAF added to 1.641 g, and the amount of PDA added to 3.881 g, and 1,2-dimethylimidazole was not added.

[0085] <Comparative Example 3> A polyamic acid solution was obtained in the same manner as in Comparative Example 1, except that the amount of BPDA added was changed to 8.107 g, the amount of BPAF added to 3.158 g, and the amount of PDA added to 3.734 g, and 1,2-dimethylimidazole was not added.

[0086] <Comparative Example 4> A polyamic acid solution was obtained in the same manner as in Example 1, except that the amount of BPDA added was changed to 10.950g, the amount of BPAF added to 0g, the amount of PDA added to 4.023g, and the amount of PAM-E added to 0.028g.

[0087] <Comparative Example 5> A polyamic acid solution was obtained in the same manner as in Comparative Example 2, except that the amount of BPDA added was 8.643 g, the amount of BPAF added was 2.565 g, the amount of PDA added was 3.792 g, PAM-E was 0 g, and 3-aminopropyltriethoxysilane (APS) was added to a total of 0.05% by weight.

[0088] <Comparative Example 6> A polyamic acid solution was obtained in the same manner as in Comparative Example 5, except that APS was added to a concentration of 0.2% by weight.

[0089] <Comparative Example 7> A polyamic acid solution was obtained in the same manner as in Comparative Example 5, except that APS was added to a concentration of 0.3% by weight.

[0090] <Comparative Example 8> In a 300 mL glass separable flask equipped with a stirrer featuring stainless steel impellers and a nitrogen inlet tube, 4.166 g of trans-1,4-cyclohexanediamine (CHDA), 0.046 g of PAM-E, and 85 g of NMP were charged and stirred at room temperature (23°C) until dissolved. After 30 minutes, 10.788 g of BPDA was added, the mixture was heated at 80°C for 30 minutes, then cooled to room temperature and stirred for 5 hours to obtain a polyamic acid solution. Further, 1,2-dimethylimidazole was added to this solution to a concentration of 1% by weight relative to the polyamic acid (resin component) and dissolved.

[0091] [Fabrication of polyimide films] Each of the polyamic acid solutions obtained in the above examples and comparative examples was diluted with NMP to a polyamic acid concentration of 10.0% by weight. Using a spin coater, the diluted polyamic acid solution was cast onto a 10 mm × 10 mm square alkali-free glass plate (Corning Eagle XG, 0.7 mm thick) so that the thickness after drying would be 10 μm. The glass plate on which the diluted polyamic acid solution was cast was dried in a hot air oven at 120°C for 30 minutes, and then imidized by heating under a nitrogen atmosphere at 430°C for 30 minutes to obtain a laminate of a 10 μm thick polyimide film and the glass plate. The polyimide film was peeled off the glass substrate of the obtained laminate and its properties were evaluated.

[0092] Table 1 shows the composition of the polyamic acid solution for each example and comparative example, as well as the evaluation results of the polyimide film. The composition in Table 1 is expressed with the total of tetracarboxylic dianhydride and diamine each set to 100 mol% (unit: mol%). The amount of 1,2-dimethylimidazole (DMI) added is the amount added per 100 parts by weight of polyamic acid (resin component) (unit: parts by weight). In the table, "Stress" represents the internal stress generated between the polyimide film and the support. Also, "-" in the table indicates that measurement was not performed.

[0093] [Table 1] As shown in Table 1, in Examples 1 to 16, which use a polyamic acid that is a polyaddition reaction product of a diamine and a tetracarboxylic dianhydride, wherein the diamine contains 1,4-phenylenediamine and 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and the tetracarboxylic dianhydride contains 3,3,4,4-biphenyltetracarboxylic dianhydride and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride, the resulting polyimide films have the following properties.

[0094] • Adhesion to glass of 0.10 N / cm or higher • Adhesion to SiO2 is 0.05 N / cm or higher. • YI is 20 or less Furthermore, when 3,3',4,4'-biphenyltetracarboxylic acid dianhydride accounts for 70-99 mol% and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride accounts for 1-30 mol% of the total tetracarboxylic dianhydride (100 mol%), and 1,4-phenylenediamine is used as the diamine, the resulting polyimide film has the following properties.

[0095] • Adhesion to glass of 0.10 N / cm or higher • Adhesion to SiO2 is 0.05 N / cm or higher. • Internal stress is 30 MPa or less • YI is 20 or less The polyimide film of Example 16, in which 3,3',4,4'-biphenyltetracarboxylic acid dianhydride was present in a proportion of 50 mol% and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride in a proportion of 50 mol% relative to a total of 100 mol% of all tetracarboxylic dianhydrides, exhibited excellent adhesion to glass and silicon oxide films and had a low YI value, but it was found that the internal stress was higher compared to other examples.

[0096] The polyimide films of Comparative Examples 1-3, which did not use 1,3-bis(3-aminopropyl)tetramethyldisiloxane as a monomer, exhibited low internal stress and high transparency, but had poor adhesion to glass and silicon oxide films, resulting in significant delamination between the SiOx or glass substrate and the polyimide film after heating tests.

[0097] The polyimide film of Comparative Example 4, which does not use 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride as a monomer, exhibits excellent adhesion to glass and silicon oxide films, no lifting occurs between the SiOx or glass substrate and the polyimide film after heating tests, and has low internal stress, but has a high YI value and low transparency.

[0098] Comparative Example 5, a polyimide film that did not use 1,3-bis(3-aminopropyl)tetramethyldisiloxane as a monomer and contained 0.05 phr of 3-aminopropyltriethoxysilane (APS), exhibited low internal stress and high transparency, but had poor adhesion to glass and silicon oxide films, resulting in significant delamination between the SiOx or glass substrate and the polyimide film after heating tests.

[0099] Comparative Examples 6 and 7, which did not use 1,3-bis(3-aminopropyl)tetramethyldisiloxane as a monomer and contained 0.2 phr to 0.3 phr of 3-aminopropyltriethoxysilane (APS), exhibited low internal stress and high transparency, but had poor adhesion to silicon oxide films, resulting in delamination between the SiOx or glass substrate and the polyimide film after heating tests.

[0100] In Comparative Example 8, the polyimide film, which did not use 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride as a monomer and used CHDA instead of PDA, was damaged by thermal decomposition after the heating test.

[0101] These results confirm that the polyimide obtained by introducing 1,3-bis(3-aminopropyl)tetramethyldisiloxane into a polyamic acid consisting of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride, and 1,4-phenylenediamine according to one embodiment of the present invention exhibits excellent heat resistance, high adhesion to glass and silicon oxide films, and high transparency.

[0102] Furthermore, polyimides obtained by introducing 1,3-bis(3-aminopropyl)tetramethyldisiloxane into polyamic acid using 1,4-phenylenediamine as the diamine, with 3,3',4,4'-biphenyltetracarboxylic acid dianhydride accounting for 70-99 mol% and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride accounting for 1-30 mol% of the total tetracarboxylic dianhydrides, were confirmed to have excellent heat resistance, high adhesion to glass and silicon oxide films, low internal stress with inorganic substrates, and high transparency.

[0103] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

Claims

1. A polyamic acid obtained as a polyaddition reaction product of a diamine and a tetracarboxylic dianhydride, wherein the diamine comprises 1,4-phenylenediamine and 1,3-bis(3-aminopropyl)tetramethyldisiloxane, and the tetracarboxylic dianhydride comprises 3,3',4,4'-biphenyltetracarboxylic dianhydride and 9,9-bis(3,4-dicarboxyphenyl)fluorenic acid dianhydride. A polyamic acid in which the proportion of 1,3-bis(3-aminopropyl)tetramethyldisiloxane to the total amount of the diamine is 0.1 mol% to 10.0 mol%.

2. The polyamic acid according to claim 1, wherein the proportion of 3,3',4,4'-biphenyltetracarboxylic dianhydride to the total amount of tetracarboxylic dianhydride is 70 mol% to 99 mol%.

3. A polyamic acid solution containing the polyamic acid described in claim 1 or 2 and an organic solvent.

4. The polyamic acid solution according to claim 3, further containing imidazoles.

5. The polyamic acid solution according to claim 4, wherein the content of the imidazoles is 0.10 mol or less per mol of amide groups of the polyamic acid.

6. A polyimide characterized by being an imidized product of a polyamic acid solution according to any one of claims 3 to 5.

7. The polyimide according to claim 6, wherein the yellowness (YI) at a film thickness of 10 μm is 20 or less.

8. A method for manufacturing a laminate of a polyimide substrate and a support, A method for producing a laminate, comprising casting a polyamic acid solution according to any one of claims 3 to 5 onto a support and imidizing it to form a polyimide substrate on the support.

9. A laminate of a polyimide substrate and a support made of the polyimide described in claim 6 or 7.

10. The laminate according to claim 9, wherein the internal stress generated between the polyimide substrate and the support is 30 MPa or less.

11. An electronic device comprising electrodes and / or electronic elements on a polyimide substrate according to claim 9 or 10.

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