Polyimide resin film and preparation method thereof

Abstract

The invention provides a polyimide resin film and a preparation method thereof, preparation raw materials of polyamide acid slurry comprise aromatic diamine, aromatic dianhydride, a functional monomer, a solvent and a coupling agent, and the functional monomer comprises amide containing double amino groups and / or amide containing double anhydride groups; the specific amide is added into the preparation raw materials to serve as a functional monomer, and the coupling agent is added in a matched mode, so that a polyimide coating formed after the obtained polyamide acid slurry is subjected to high-temperature imidization has excellent heat resistance and adhesion performance and also has excellent chemical peelability; and after being infiltrated into a chemical reagent, the coating can be quickly dissolved or fused, so that the coating can be quickly and thoroughly stripped from a base material without damaging the base material, and the coating is suitable for a protective coating of an optical fiber.

Description

[0001] This application is a divisional application. The application number of the parent application is 202410396451.5, the application date is April 2, 2024, and the name of the invention is "A polyamic acid slurry, its preparation method and application". Technical Field

[0002] The invention relates to the technical field of coatings, and in particular to a polyimide resin film and a preparation method thereof. Background Art

[0003] Optical fiber is short for optical fiber, which is a fiber made of glass or plastic. It can be used as a light transmission tool and is suitable for large-scale data transmission and interference-free data transmission in the telecommunications field. It will not be affected by electric or magnetic fields. In order to improve the strength and flexibility of optical fiber, a protective layer is usually coated on the outer layer of the optical fiber. The material of the protective layer is mainly polymethyl methacrylate (PMMA). The glass transition temperature of traditional PMMA is generally around 100°C, and even the glass transition temperature of modified PMMA will not exceed 150°C. Due to working conditions, signal transmission needs to be achieved in a high temperature (over 250°C) environment, such as sensor signal transmission of aerospace vehicles, oil mine exploration signal transmission, etc.

[0004] Coating a protective layer on the outer layer of the optical fiber is mainly to protect the internal optical fiber. In actual use, the interface part needs to be stripped of the protective layer before use. Conventional stripping schemes include physical stripping and chemical stripping. Among them, although physical stripping can effectively remove the protective layer, it is easy to damage the optical fiber layer; chemical stripping mainly involves immersing the optical fiber in chemical reagents to soften, dissolve or decompose it, which is not only highly efficient but also will not damage the optical fiber layer.

[0005] CN1222897A discloses a method for manufacturing a coated optical fiber with a strippable polyimide coating, the method comprising the following steps: pulling the optical fiber through a curable polyamide acid solution to form a coating on the fiber and curing the coated fiber, and then exposing the cured coating to a polar organic solvent such as acetone to strip the cured coating from the optical fiber; the invention also provides a fiber with a strippable polyimide coating, the method is particularly suitable for heavy metal fluoride fibers and chalcogenide fibers that transmit optical signals in the infrared region. The method can effectively strip the protective layer; however, in actual use, it is found that the adhesion between the fluorine-containing coating and the optical fiber is low, and the joint after corrosion is easy to further separate, which reduces the degree of protection for the optical fiber.

[0006] Therefore, developing a polyamic acid slurry having excellent heat resistance, adhesion and chemical strippability is still a technical problem that needs to be urgently solved in the art. Summary of the invention

[0007] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a polyimide resin film and a preparation method thereof. The polyimide coating formed by the imidization reaction of the polyamic acid slurry has excellent heat resistance and substrate adhesion, and also has excellent chemical strippability, and is suitable for use as a protective coating for optical fibers.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a polyamic acid slurry, wherein the raw materials for preparing the polyamic acid slurry include aromatic diamine, aromatic dianhydride, functional monomer, solvent and coupling agent;

[0010] The functional monomer includes amide containing a bisamino group and / or amide containing a bisanhydride group.

[0011] The raw materials for preparing the polyamic acid slurry provided by the present invention include aromatic diamines, aromatic dianhydrides, functional monomers, solvents and coupling agents, and the functional monomers include amides containing diamino groups and / or amides containing dianhydride groups; by adding the above-mentioned amides containing diamino groups and / or dianhydride groups as functional monomers to the raw materials for preparation to participate in copolymerization to form polyamic acid, and adding a coupling agent, the obtained polyamic acid slurry has excellent heat resistance and chemical strippability, and the polyimide coating formed after high-temperature imidization not only has high adhesion to the substrate, but is also not easy to detach from the substrate under high-temperature conditions, and also has excellent chemical strippability, can be quickly dissolved or melted after being infiltrated into a chemical reagent (such as sulfuric acid), and can then be quickly stripped from the substrate without damaging the substrate, and is suitable for use in protective coatings for optical fibers.

[0012] Preferably, the mass percentage of aromatic diamine and aromatic dianhydride in the raw materials for preparing the polyamic acid slurry is 18-32%, such as 20%, 22%, 24%, 26%, 28% or 30%, and more preferably 19-30%.

[0013] As a preferred technical solution of the present invention, limiting the mass percentage of aromatic diamine and aromatic dianhydride in the preparation raw materials of the polyamic acid slurry to 18-32% can make the obtained polyamic acid slurry have excellent coating performance, and after forming the polyimide coating, it has excellent mechanical properties. If the mass percentage of the two is too low, it will lead to too many coating passes and the strength of the formed polyimide coating will be reduced. If the mass percentage of the two is too high, the slurry viscosity will be too high, which is not conducive to production.

[0014] Preferably, the molar ratio of anhydride groups to amino groups in the preparation raw materials is 1:(0.95-1.05), for example, 1:0.96, 1:0.97, 1:0.98, 1:0.99, 1:1, 1:1.01, 1:1.02, 1:1.03 or 1:1.04, etc.

[0015] Preferably, the aromatic diamine includes any one of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 4,4'-diaminobenzanilide, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 4,4'-diaminodiphenyl sulfone, 2-(4-aminophenyl)-5-aminobenzimidazole, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 4,4'-diamino-biphenyl or 9,9-bis(4-aminophenyl)fluorene, or a combination of at least two thereof.

[0016] Preferably, the aromatic dianhydride comprises aromatic tetracarboxylic dianhydride.

[0017] Preferably, the aromatic tetracarboxylic dianhydride includes 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, (4-phthalic anhydride)formyloxy-4-phthalate, bis[(3,4-dianhydride)phenyl]terephthalate, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, p-phenylene-diphenyltrimethic acid Any one of ester dianhydride, 4,4'-terephthalic anhydride, pyromellitic dianhydride, 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride, 2,2-bis(4-(3,4-dicarboxyphenoxy)phenyl)hexafluoropropane dianhydride, 2,2-bis(4-(3,4-dicarboxybenzoyloxy)phenyl)hexafluoropropane dianhydride or 2,2'-bis(trifluoromethyl)-4,4'-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride or a combination of at least two thereof.

[0018] Preferably, the functional monomer comprises an amide containing a diamino group, and the molar ratio of the amide containing a diamino group to the aromatic diamine is 1:(1-10), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8 or 1:9, etc., and more preferably 1:(3-10).

[0019] As a preferred technical solution of the present invention, if the addition ratio of the amide containing the diamino group is too high, the high temperature resistance of the polyamic acid slurry will be reduced to a certain extent, and the requirement of long-term use under high temperature will not be met. If the addition ratio of the amide containing the diamino group is too low, the chemical stripping of the polyimide coating formed by the polyamic acid slurry will be incomplete or the stripping time will be too long, and the chemical strippability will be reduced.

[0020] Preferably, the diamino-containing amide has at least one of the following structures:

[0021]

[0022] In the above structure, R is independently selected from H, methyl, ethyl or -CF 3 Any one of, X is independently selected from -O-, -S- or -SO 2 -Any one of the following.

[0023] Preferably, the amide containing a diamino group is selected from the following compounds M1 or M2;

[0024]

[0025] Among them, the above compound M1 is N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide), referred to as AB-TFDB, CAS No.: 1449757-11-2; the above compound M2 is 4,4'-diaminobenzanilide, referred to as DABA.

[0026] Preferably, the functional monomer includes an amide containing a bisanhydride group, and the molar ratio of the amide containing a bisanhydride group to the aromatic dianhydride is 1:(1-10), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8 or 1:9, etc., and more preferably 1:(3-10).

[0027] As a preferred technical solution of the present invention, if the addition ratio of the amide containing bisanhydride groups is too high, the high temperature resistance and adhesion of the polyamic acid slurry will be reduced to a certain extent, and the requirements for long-term use under high temperature will not be met. If the addition ratio of the amide containing bisanhydride groups is too low, the chemical stripping of the polyimide coating formed by the polyamic acid slurry will be incomplete or the stripping time will be too long, and the chemical strippability will be reduced.

[0028] Preferably, the amide containing a bisanhydride group has at least one of the following structures:

[0029]

[0030] In the above structure, R is independently selected from H, methyl, ethyl or -CF 3 Any one of, X is independently selected from -O-, -S-, -SO 2 - or methylene.

[0031] Preferably, the amide containing a bisanhydride group is selected from the following compound N1;

[0032]

[0033] The above compound N1 is N,N'-(2,2-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(1,3-dioxy-1,3-dihydroisobenzofuran-5-carboxamide, referred to as TA-TFMB, and its CAS number is: 1226511-56-3.

[0034] Preferably, the solvent comprises a non-protonated organic solvent, preferably any one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, γ-butyrolactone, propylene glycol monomethyl ether, cyclopentanone, cyclohexanone, ethyl acetate, toluene or methyl ethyl ketone or a combination of at least two thereof, more preferably N,N-dimethylformamide and N,N-dimethylacetamide.

[0035] Preferably, the coupling agent comprises a silane coupling agent.

[0036] In the present invention, there is no special requirement for the specific type of the silane coupling agent, and a conventional commercial silane coupling agent can be selected. For example, γ-glycidyloxypropyltrimethoxysilane (KH560) can be selected.

[0037] Preferably, the raw materials for preparing the polyamic acid coating also include a capping agent.

[0038] Preferably, the end-capping agent includes a monoamine compound or a monocarboxylic acid compound.

[0039] Preferably, the viscosity of the polyamic acid slurry is 3000-30000 cp (eg, 5000, 7000, 9000, 13000, 15000, 19000, 21000, 25000, 27000 or 29000, etc.), more preferably 5000-15000 cp.

[0040] In a second aspect, the present invention provides a method for preparing the polyamic acid slurry as described in the first aspect, the preparation method comprising: copolymerizing aromatic diamine, aromatic dianhydride and functional monomer in a solvent, adding a coupling agent and mixing to obtain the polyamic acid slurry.

[0041] Preferably, the copolymerization reaction temperature is 25 to 60°C, such as 30°C, 35°C, 40°C, 45°C, 50°C or 55°C, and more preferably 35 to 55°C.

[0042] Preferably, the copolymerization reaction time is 3 to 24 h, for example, 4 h, 5 h, 6 h, 7 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h or 22 h.

[0043] Preferably, after the reaction is completed, a step of adding a capping agent for capping is further included.

[0044] In a third aspect, the present invention provides a polyimide resin, wherein the polyamide-imide resin is obtained by subjecting the polyamic acid slurry described in the first aspect to an imidization reaction.

[0045] Preferably, the temperature of the imidization reaction is 60-400°C, such as 100°C, 150°C, 200°C, 250°C, 300°C or 350°C, etc. In a fourth aspect, the present invention provides a polyimide optical fiber, comprising a bare optical fiber and the polyimide resin as described in the third aspect coated on the bare optical fiber.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The raw materials for preparing the polyamic acid slurry provided by the present invention include aromatic diamine, aromatic dianhydride, functional monomer, solvent and coupling agent, and the functional monomer includes amide containing diamino group and / or amide containing dianhydride group; by adding amide containing diamino group and / or amide containing dianhydride group as functional monomers in the raw materials for preparation, and adding coupling agent, the polyimide coating formed by the obtained polyamic acid slurry after high-temperature imidization has excellent high temperature resistance and adhesion performance, and also has excellent chemical strippability, can be quickly dissolved or melted when immersed in chemical reagents, and can then be quickly and thoroughly stripped from the substrate without damaging the substrate, and is suitable for use as a protective coating for optical fibers;

[0048] (2) By further limiting the molar ratio of the functional monomer to the aromatic diamine or aromatic dianhydride, the polyimide film formed by the imidization of the obtained polyamic acid slurry can have a tensile strength of up to 136-154 MPa, an elongation at break of 54-71%, an adhesion to the substrate of up to 4B-5B, a Tg of 275-391°C, and a dissolution time of only 3-12 min, thereby having more excellent mechanical properties, substrate adhesion properties, heat resistance and chemical strippability. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0050] Unless otherwise specified, the raw materials involved in the specific implementation methods of the present invention are all conventional commercially available materials, and the instruments and equipment involved are all conventional instruments and equipment in the art.

[0051] In particular, the test methods for solid content and viscosity involved in the specific embodiments of the present invention are as follows:

[0052] (1) Viscosity: The viscosity of the paint was tested at 25°C using an American Boller cone and plate viscometer.

[0053] (2) Solid content: Take an aluminum foil disk with a diameter of 60 mm and weigh it 0 ; Take 1±0.1g of paint sample and place it in an aluminum pan, weigh the weight of the aluminum pan plus the paint (m 1 ); Place the aluminum plate containing the paint in a blast oven at 180±5℃, take it out after 1 hour, and weigh the mass of the aluminum plate containing the paint (m 2 ); solid content = (m 2 -m 0 ) / (m 1 -m 0 )×100%.

[0054] Example 1

[0055] A polyamic acid slurry having a viscosity of 8940 cp and a solid content of 22.5%;

[0056] The preparation method of the polyamic acid slurry comprises: adding N,N-dimethylacetamide (DMAc, 616g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 79.5g, 0.4mol) into the reactor, then heating the reactor temperature to 40°C, adding pyromellitic dianhydride (PMDA, 77.94g, 0.36mol) and compound N1 (TA-TFMB, CAS No.: 1226511-56-3, 26.54g, 0.04mol), maintaining the copolymerization reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0057] Example 2

[0058] A polyamic acid slurry having a viscosity of 7438 cp and a solid content of 22.4%;

[0059] The preparation method of the polyamic acid slurry includes: adding N,N-dimethylacetamide (DMAc, 616g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 66.79g, 0.33mol) into the reactor, then heating the reactor temperature to 40°C, and adding 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA, 95.7g, 0.3mol) and compound N1 (TA-TFMB, CAS No.: 1226511-56-3, 22.07g, 0.03mol), maintaining the copolymerization reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0060] Example 3

[0061] A polyamic acid slurry having a viscosity of 9574cp and a solid content of 22.2%;

[0062] The preparation method of the polyamic acid slurry includes: adding N,N-dimethylacetamide (DMAc, 616g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 72.99g, 0.36mol) and compound M1 (AB-TFDB, CAS No.: 1449757-11-2, 22.63g, 0.04mol) into the reactor, then heating the reactor temperature to 40°C, adding pyromellitic dianhydride (PMDA, 88.34g, 0.4mol), maintaining the copolymerization reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0063] Example 4

[0064] A polyamic acid slurry having a viscosity of 7915 cp and a solid content of 22.4%;

[0065] The preparation method of the polyamic acid slurry includes: adding N,N-dimethylacetamide (DMAc, 616g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 59.4g, 0.3mol) and compound M1 (AB-TFDB, CAS No.: 1449757-11-2, 18.3g, 0.03mol) into the reactor, then heating the reactor temperature to 40°C, adding 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA, 106.3g, 0.33mol), maintaining the copolymerization reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0066] Example 5

[0067] A polyamic acid slurry having a viscosity of 11240 cp and a solid content of 19.6%;

[0068] The preparation method of the polyamic acid slurry comprises: adding N,N-dimethylacetamide (DMAc, 640g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 68.48g, 0.34mol) and compound M2 (4,4'-diaminobenzanilide, DABA, 8.63g, 0.04mol) into the reactor, then heating the reactor temperature to 40°C, adding pyromellitic dianhydride (PMDA, 82.88g, 0.38mol), maintaining the copolymerization reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0069] Example 6

[0070] A polyamic acid slurry having a viscosity of 8341 cp and a solid content of 19.8%;

[0071] The preparation method of the polyamic acid slurry comprises: adding N,N-dimethylacetamide (DMAc, 640g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 54.96g, 0.27mol) and compound M2 (4,4'-diaminobenzanilide, DABA, 6.92g, 0.03mol) into the reactor, then heating the reactor temperature to 40°C, adding 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA, 98.28g, 0.3mol), maintaining the copolymerization reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0072] Example 7

[0073] A polyamic acid slurry, which is different from Example 1 in that the added amount of compound N1 (TA-TFMB) is 0.1 mol, the added amount of pyromellitic dianhydride is 0.3 mol, and other components, amounts and preparation methods are the same as those in Example 1.

[0074] Example 8

[0075] A polyamic acid slurry, which is different from Example 1 in that the added amount of compound N1 (TA-TFMB) is 0.2 mol, the added amount of pyromellitic dianhydride is 0.2 mol, and the other components, amounts and preparation methods are the same as those in Example 1.

[0076] Example 9

[0077] A polyamic acid slurry, which is different from Example 1 in that the added amount of compound N1 (TA-TFMB) is 0.3 mol, the added amount of pyromellitic dianhydride is 0.1 mol, and other components, amounts and preparation methods are the same as those in Example 1.

[0078] Comparative Example 1

[0079] A polyamic acid slurry having a viscosity of 13655 cp and a solid content of 19.1%;

[0080] The preparation method of the polyamic acid slurry comprises: adding N,N-dimethylacetamide (DMAc, 640g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 76.58g, 0.38mol) into the reactor, then heating the reactor temperature to 40°C, adding pyromellitic dianhydride (PMDA, 83.42g, 0.38mol), maintaining the reaction temperature at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0081] Comparative Example 2

[0082] A polyamic acid slurry having a viscosity of 10145 cp and a solid content of 19%;

[0083] The preparation method of the polyamic acid slurry comprises: adding N,N-dimethylacetamide (DMAc, 640g) into a 1L reactor, then adding 4,4'-diaminodiphenyl ether (ODA, 61.32g, 0.3mol) into the reactor, then heating the reactor temperature to 40°C, adding 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA, 98.67g, 0.3mol), maintaining the reaction at 40°C for 10h, finally lowering the system temperature to room temperature, adding γ-glycidyloxypropyltrimethoxysilane (0.8g) and stirring for 2h to obtain the polyamic acid slurry.

[0084] Comparative Example 3

[0085] A polyamic acid slurry, which differs from Example 1 in that γ-glycidyloxypropyltrimethoxysilane is not added for stirring, and other substances, amounts and steps are the same as those in Example 1.

[0086] Performance Test:

[0087] (1) Tensile strength and elongation at break: The polyamic acid slurry is first subjected to high-temperature imidization to obtain a polyimide film sample; wherein the high-temperature imidization conditions are: heating at a temperature of 60 to 400°C for 8 h at a heating rate of 5°C / min;

[0088] The polyimide film samples were then tested according to JIS K7127. The test conditions were: using an electric mechanical universal testing machine (manufactured by INSTRON) with a test speed of 5 m / min and a load cell of 5 kN and 0.05 N for tensile testing.

[0089] (2) Adhesion: Referring to ASTM D3359-09, the adhesion of the polyimide coating formed by coating the polyamic acid slurry on the glass surface was measured by tape.

[0090] (3) Tg: The polyamic acid slurry is first subjected to high temperature imidization to obtain a polyimide resin film; wherein the conditions for the high temperature imidization are: heating at a temperature rise rate of 5°C / min in a range of 60 to 400°C for 8 hours;

[0091] Then, it was tested using a scanning differential thermal analyzer (TAInstrument, model Q200).

[0092] (4) Chemical strippability: The polyamic acid slurry was first subjected to high-temperature imidization to obtain a polyimide resin with a thickness of 25 μm. The high-temperature imidization conditions were as follows: heating at a heating rate of 5°C / min in the range of 60 to 400°C for 8 h. The polyimide resin was then cut into 5×5 mm films and immersed in concentrated sulfuric acid (concentration of 98%). The film dissolution or dissolution time was recorded.

[0093] The polyamic acid slurries provided in Examples 1 to 9 and Comparative Examples 1 to 3 were tested according to the above test method. The test results are shown in Table 1:

[0094] Table 1

[0095] Tensile strength / MPa Elongation at break / % Adhesion Tg / ℃ Dissolution time / min Example 1 154 65 4B 378 5 Example 2 143 58 4B 268 4 Example 3 136 62 4B 391 4 Example 4 138 54 4B 275 3 Example 5 145 71 5B 411 12 Example 6 141 65 5B 294 9 Example 7 168 75 3B 334 3 Example 8 179 81 2B 298 2 Example 9 185 85 1B 238 0.5 Comparative Example 1 128 85 5B 399 Insoluble Comparative Example 2 131 64 5B 280 Insoluble Comparative Example 3 150 68 1B 378 5

[0096] From the data in Table 1, we can see that:

[0097] (1) The polyimide film formed by imidization of the polyamic acid slurry provided in Examples 1 to 6 has a tensile strength of up to 136 to 154 MPa, an elongation at break of 54 to 71%, an adhesion to the substrate of up to 4B to 5B, a Tg of 275 to 391°C, and a dissolution time of only 3 to 12 min, and has excellent mechanical properties, substrate adhesion, heat resistance, and chemical strippability;

[0098] (2) Although the polyimide film formed by imidization of the polyamic acid slurry provided in Comparative Examples 1 and 2 also has excellent mechanical properties, substrate adhesion and heat resistance, the chemical strippability test shows that it is still difficult to dissolve after being immersed in concentrated sulfuric acid for 8 hours, indicating that the polyimide coating further obtained from the polyamic acid slurry obtained by copolymerization without adding functional monomers does not have chemical strippability;

[0099] (3) The substrate adhesion of the polyimide formed by imidization of the polyamic acid slurry provided in Comparative Example 3 is poor, which is caused by the fact that no coupling agent is added.

[0100] (4) Since the molar ratio of the amide containing bisanhydride groups and pyromellitic dianhydride used in the polyamic acid slurries provided in Examples 7 to 9 is not within the preferred range, the resulting polyimide film cannot have excellent heat resistance, substrate adhesion and chemical strippability.

[0101] The applicant declares that the present invention illustrates a polyamic acid slurry and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a polyimide resin film, characterized in that: The polyimide resin film is obtained by subjecting polyamic acid slurry to imidization reaction; The temperature of the imidization reaction is 60-400°C; The raw materials for preparing the polyamic acid slurry include aromatic diamine, aromatic dianhydride, functional monomer, solvent and coupling agent; The functional monomers include amides containing diamino groups and / or amides containing dianhydride groups; The aromatic dianhydride is pyromellitic dianhydride; the aromatic diamine is 4,4'-diaminodiphenyl ether; The mass percentage of aromatic diamine and aromatic dianhydride in the raw materials for preparing the polyamic acid slurry is 19-30%; The molar ratio of anhydride groups to amino groups in the raw materials for preparing the polyamic acid slurry is 1:0.95-1.05; The amide containing a diamino group is selected from the following compounds M1 or M2:

2. The method for preparing a polyimide resin film according to claim 1, wherein: The molar ratio of the amide containing diamino group to the aromatic diamine is 1:1 to 10; The molar ratio of the amide containing bis-anhydride groups to the aromatic dianhydride is 1:1 to 10; The amide containing a bisanhydride group is selected from the following compound N1:

3. The method for preparing a polyimide resin film according to claim 2, characterized in that: The solvent includes a non-protonated organic solvent, preferably any one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, γ-butyrolactone, propylene glycol monomethyl ether, cyclopentanone, cyclohexanone, ethyl acetate, toluene or methyl ethyl ketone or a combination of at least two thereof, and more preferably N,N-dimethylformamide and N,N-dimethylacetamide; The coupling agent includes a silane coupling agent.

4. The method for preparing a polyimide resin film according to claim 3, characterized in that: The raw materials for preparing the polyamic acid coating also include a capping agent; The end-capping agent includes a monoamine compound or a monocarboxylic acid compound.

5. The method for preparing a polyimide resin film according to claim 4, characterized in that: The viscosity of the polyamic acid slurry is 3000-30000cp.

6. The method for preparing a polyimide resin film according to claim 5, characterized in that: The preparation method of the polyamic acid slurry comprises: copolymerizing aromatic diamine, aromatic dianhydride and functional monomer in a solvent, adding a coupling agent and mixing, so as to obtain the polyamic acid slurry.

7. The preparation method according to claim 6, characterized in that: The temperature of the copolymerization reaction is 25 to 60° C. The copolymerization reaction time is 3 to 24 hours; After the copolymerization reaction is completed, the step of adding a capping agent for capping is also included.

8. The polyimide resin film prepared by the preparation method according to any one of claims 1 to 7.

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