A kind of high temperature resistant acrylic pressure-sensitive adhesive and preparation method thereof

Abstract

The present invention belongs to the technical field of polymer materials, and specifically relates to a high temperature resistant acrylic pressure-sensitive adhesive and a preparation method thereof. The preparation method comprises the following steps: a cyclosiloxane monomer, isocyanate propylmethyldimethoxysilane and a methylsilane end-capping agent are subjected to polymerization reaction under a catalyst and anhydrous conditions to obtain an isocyanate polysiloxane; then the isocyanate polysiloxane is subjected to a heat preservation cross-linking reaction with an acrylic prepolymer solution to obtain an acrylic pressure-sensitive adhesive liquid; the obtained acrylic pressure-sensitive adhesive liquid is applied to one or both sides of a PI substrate, heated and dried to obtain a pressure-sensitive adhesive layer, and then a release film is applied to the surface of the pressure-sensitive adhesive layer to obtain a high temperature resistant acrylic single-sided adhesive or double-sided adhesive. The acrylic pressure-sensitive adhesive of the present invention adopts a high temperature resistant PI substrate, and the pressure-sensitive adhesive layer adopts a specific isocyanate polysiloxane for cross-linking modification, which can significantly improve its high temperature bonding performance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a high temperature resistant acrylic pressure sensitive adhesive and a preparation method thereof. Background Art

[0002] In recent years, there is a great demand for high temperature resistant pressure sensitive adhesive tapes in the field of electronic product material manufacturing. During the processing of electronic product materials, pressure sensitive adhesive tapes may have to withstand high temperatures (120-260°C) for a period of time in order to heat treat the electronic product materials. However, conventional acrylic pressure sensitive adhesives and substrates are difficult to achieve stable bonding performance under high temperature conditions.

[0003] Silicone has been widely used in the high-temperature modification of acrylic pressure-sensitive adhesives due to its good high-temperature resistance and flexibility. For example, the invention patent CN 108728025 A discloses a method for preparing a silicone-modified high-temperature pressure-sensitive adhesive, which uses 2-octyl-1-dodecyl acrylate and polyester-modified polydimethylsiloxane modified with acrylic functional groups to make the properties of the high-temperature resistant monomer and the high-temperature resistant silicone monomer work together efficiently and show excellent compatibility and adaptability. However, the polymerization efficiency of polydimethylsiloxane is low during the modification process by free radical copolymerization, and a specific compatibilizer needs to be used for compounding. The scope of application of its formula is narrow, and the flexibility of performance adjustment is limited.

[0004] In addition, the substrates currently used for acrylic pressure-sensitive adhesives are mainly polyester, polyamide, polyethylene, polypropylene, polycarbonate, polyimide, etc. Among them, polyimide has significant advantages in the preparation of high-temperature resistant pressure-sensitive adhesive tapes due to its higher strength and high-temperature resistance. However, polyimide has poor flexibility, which affects the bonding stability of pressure-sensitive adhesives in processes with large deformation (such as roller crushing of soft magnetic material sheets, etc.). Summary of the invention

[0005] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a high temperature resistant acrylic pressure-sensitive adhesive.

[0006] Another object of the present invention is to provide a high temperature resistant acrylic pressure sensitive adhesive prepared by the above method.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a high temperature resistant acrylic pressure-sensitive adhesive comprises the following preparation steps:

[0009] (1) subjecting a cyclosiloxane monomer, isocyanate propylmethyldimethoxysilane and a methylsilane end-capping agent to a polymerization reaction in the presence of a catalyst and anhydrous conditions to obtain an isocyanate polysiloxane;

[0010] (2) adding acrylic acid monomer, acrylic ester monomer and functional monomer into an organic solvent, adding an initiator under nitrogen protection, heating and polymerization reaction, and obtaining an acrylic acid prepolymer solution;

[0011] (3) adding the isocyanate polysiloxane obtained in step (1) to the acrylic prepolymer solution in step (2) to carry out a cross-linking reaction at a temperature of 100 °C to obtain an acrylic pressure-sensitive adhesive solution;

[0012] (4) coating the acrylic pressure-sensitive adhesive solution obtained in step (3) on one or both sides of a polyimide (PI) substrate, heating and drying to solidify the surface to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain a high-temperature resistant acrylic single-sided adhesive or double-sided adhesive.

[0013] Preferably, the cyclosiloxane monomer in step (1) is octamethylcyclotetrasiloxane (D4) or dimethylsiloxane mixed ring (DMC); the methylsilane end-capping agent is hexamethyldisiloxane (MM), methoxytrimethylsilane or trimethylchlorosilane; the mass ratio of the cyclosiloxane monomer, isocyanatepropylmethyldimethoxysilane and methylsilane end-capping agent added is 100:10~40:1~10.

[0014] Preferably, the catalyst in step (1) is sodium siliconate or potassium siliconate; the polymerization reaction temperature is 100 to 140° C., and the polymerization reaction time is 2 to 8 hours.

[0015] Preferably, the acrylic acid monomer in step (2) is one or both of acrylic acid and methacrylic acid; the acrylic acid ester monomer is one or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate, and lauryl methacrylate; and the functional monomer is one or more of acrylamide, acrylonitrile, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and styrene.

[0016] Preferably, the mass ratio of the acrylic acid monomer, the acrylic ester monomer and the functional monomer in step (2) is 1:1-3:0.5-2.

[0017] Preferably, the organic solvent in step (2) is one or more of toluene, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide; the initiator is dibenzoyl peroxide or azobisisobutyronitrile; the temperature of the heating polymerization reaction is 60-80° C., and the time is 3-6 hours.

[0018] Preferably, the amount of the isocyanate polysiloxane added in step (3) is 10 to 50% of the total mass of the acrylic monomer, acrylate monomer and functional monomer in step (2); the temperature of the heat preservation cross-linking reaction is 60 to 80° C., and the time is 1 to 3 hours.

[0019] Preferably, the PI substrate in step (4) refers to an organosilicon-modified PI substrate prepared by the following method:

[0020] The dianhydride monomer, diamine monomer, dehydrating agent and catalyst are added to an organic solvent and dissolved evenly, the temperature is raised to 80-150°C for prepolymerization reaction, and then isocyanate polysiloxane is added to continue the heat preservation polymerization reaction, and the obtained silicone-modified polyimide solution is dried on a substrate to form a film to obtain a silicone-modified PI substrate.

[0021] Preferably, the dianhydride monomer is pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride, 4,4'-phenylenedioxydiphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride or 3,3',4,4'-diphenylethertetracarboxylic dianhydride; the diamine monomer is Phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobiphenyl, hexamethylenediamine or polyetherdiamine; the dehydrating agent is acetic anhydride, phthalic anhydride or maleic anhydride; the catalyst is pyridine, triethylamine or 4-dimethylaminopyridine; the organic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, toluene or tetrahydrofuran.

[0022] Preferably, the molar ratio of the dianhydride monomer and the diamine monomer is 1.2 to 1.5:1, and the prepolymerization reaction time is 2 to 6 hours; the amount of the isocyanate polysiloxane added is 20 to 60% of the total mass of the dianhydride monomer and the diamine monomer, and the heat preservation polymerization reaction time is 2 to 6 hours.

[0023] A high temperature resistant acrylic pressure-sensitive adhesive is prepared by the method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention adopts a specific isocyanate polysiloxane to crosslink and modify the acrylic pressure-sensitive adhesive, which can significantly improve its high-temperature bonding performance.

[0026] (2) The acrylic pressure-sensitive adhesive of the present invention further adopts a specific silicone-modified PI substrate, which can further enhance its high temperature resistance, moisture resistance and improve its flexibility. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0028] Example 1

[0029] (1) Octamethylcyclotetrasiloxane (D4) monomer, isocyanate propylmethyldimethoxysilane and hexamethyldisiloxane (MM) end-capping agent are added to a reaction kettle in a mass ratio of 100:20:5 and stirred to mix evenly. After nitrogen deoxygenation and water removal, the temperature is raised to 120° C., and then 0.02% of trimethylsilanol potassium catalyst is added to the reaction system and stirred for 4 hours. Unreacted raw materials are removed by vacuum extraction at 140-150° C. to obtain isocyanate polysiloxane.

[0030] (2) Acrylic acid, methyl methacrylate, butyl acrylate and hydroxyethyl acrylate are added to a toluene solvent in a mass ratio of 1:1:1:1, and dibenzoyl peroxide initiator is added under nitrogen protection, heated to 70-75° C., and polymerized for 4 hours to obtain an acrylic acid prepolymer solution with a solid content of 40%.

[0031] (3) Add the isocyanate polysiloxane obtained in step (1) to the acrylic prepolymer solution in step (2) for crosslinking reaction at 70-75°C for 2 hours to obtain an acrylic pressure-sensitive adhesive solution. The amount of the isocyanate polysiloxane added is 25% of the solid content in the acrylic prepolymer solution.

[0032] (4) coating the acrylic pressure-sensitive adhesive solution obtained in step (3) on one side of a polyimide substrate (a PI substrate conventionally prepared using pyromellitic acid dianhydride and diaminodiphenyl ether monomers), heating and drying in a vacuum drying furnace to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain a high-temperature resistant acrylic single-sided adhesive.

[0033] Example 2

[0034] (1) Octamethylcyclotetrasiloxane (D4) monomer, isocyanate propylmethyldimethoxysilane and hexamethyldisiloxane (MM) end-capping agent are added to a reaction kettle in a mass ratio of 100:10:2 and stirred to mix evenly. After deoxygenation and dehydration with nitrogen, the temperature is raised to 120° C., and then 0.02% of potassium trimethylsilanol catalyst is added to the reaction system and stirred for 4 hours. Unreacted raw materials are removed by vacuum extraction at 140-150° C. to obtain isocyanate polysiloxane.

[0035] (2) Acrylic acid, methyl methacrylate, butyl acrylate and hydroxyethyl acrylate are added to a toluene solvent in a mass ratio of 1:1:1:1, and dibenzoyl peroxide initiator is added under nitrogen protection, heated to 70-75° C., and polymerized for 4 hours to obtain an acrylic acid prepolymer solution with a solid content of 40%.

[0036] (3) Add the isocyanate polysiloxane obtained in step (1) to the acrylic prepolymer solution in step (2) for crosslinking reaction at 70-75°C for 2 hours to obtain an acrylic pressure-sensitive adhesive solution. The amount of the isocyanate polysiloxane added is 50% of the solid content in the acrylic prepolymer solution.

[0037] (4) coating the acrylic pressure-sensitive adhesive solution obtained in step (3) on one side of a polyimide substrate (a PI substrate conventionally prepared using pyromellitic acid dianhydride and diaminodiphenyl ether monomers), heating and drying in a vacuum drying furnace to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain a high-temperature resistant acrylic single-sided adhesive.

[0038] Example 3

[0039] (1) Add dimethylsiloxane mixed ring (DMC) monomer, isocyanate propylmethyldimethoxysilane and methoxytrimethylsilane capping agent into a reaction kettle in a mass ratio of 100:40:10 and stir to mix evenly. After deoxygenation and dehydration with nitrogen, heat to 130° C., then add 0.02% of potassium trimethylsilanol catalyst to the reaction system and stir to react for 4 hours. Unreacted raw materials are removed by vacuum extraction at 140-150° C. to obtain isocyanate polysiloxane.

[0040] (2) Acrylic acid, methyl methacrylate, butyl acrylate and hydroxyethyl acrylate are added to a toluene solvent in a mass ratio of 1:1:1:1, and dibenzoyl peroxide initiator is added under nitrogen protection, heated to 70-75° C., and polymerized for 4 hours to obtain an acrylic acid prepolymer solution with a solid content of 40%.

[0041] (3) Add the isocyanate polysiloxane obtained in step (1) to the acrylic prepolymer solution in step (2) for crosslinking reaction at 70-75°C for 2 hours to obtain an acrylic pressure-sensitive adhesive solution. The amount of the isocyanate polysiloxane added is 10% of the solid content in the acrylic prepolymer solution.

[0042] (4) coating the acrylic pressure-sensitive adhesive solution obtained in step (3) on one side of a polyimide substrate (a PI substrate conventionally prepared using pyromellitic acid dianhydride and diaminodiphenyl ether monomers), heating and drying in a vacuum drying furnace to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain a high-temperature resistant acrylic single-sided adhesive.

[0043] Example 4

[0044] (1) Octamethylcyclotetrasiloxane (D4) monomer, isocyanate propylmethyldimethoxysilane and hexamethyldisiloxane (MM) end-capping agent are added to a reaction kettle in a mass ratio of 100:20:5 and stirred to mix evenly. After nitrogen deoxygenation and water removal, the temperature is raised to 120° C., and then 0.02% of trimethylsilanol potassium catalyst is added to the reaction system and stirred for 4 hours. Unreacted raw materials are removed by vacuum extraction at 140-150° C. to obtain isocyanate polysiloxane.

[0045] (2) Methacrylic acid, ethyl acrylate, acrylamide and styrene were added to a toluene solvent in a mass ratio of 1:2:0.5:0.5, and azobisisobutyronitrile initiator was added under nitrogen protection, heated to 70-75° C., and polymerized for 4 hours to obtain an acrylic acid prepolymer solution with a solid content of 40%.

[0046] (3) Add the isocyanate polysiloxane obtained in step (1) to the acrylic prepolymer solution in step (2) for crosslinking reaction at 70-75°C for 2 hours to obtain an acrylic pressure-sensitive adhesive solution. The mass of the isocyanate polysiloxane added is 20% of the solid content in the acrylic prepolymer solution.

[0047] (4) coating the acrylic pressure-sensitive adhesive solution obtained in step (3) on both sides of a polyimide substrate (a PI substrate conventionally prepared from pyromellitic anhydride and diaminodiphenyl ether monomers), heating and drying in a vacuum drying oven to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain a high-temperature resistant acrylic double-sided adhesive.

[0048] Example 5

[0049] A method for preparing a high temperature resistant acrylic pressure-sensitive adhesive, compared with Example 1, the organosilicon-modified PI substrate prepared by the following method:

[0050] By mass, 140 parts of pyromellitic anhydride, 100 parts of 4,4'-diaminodiphenyl ether, 5 parts of dehydrating agent acetic anhydride and 0.3 parts of catalyst 4-dimethylaminopyridine were added to 1000 parts of N,N-dimethylformamide solvent and dissolved evenly, and the temperature was raised to 140°C for prepolymerization for 3 hours, and then 100 parts of isocyanate polysiloxane (prepared according to the method of step (1) in Example 1) was added and the polymerization reaction was continued for 4 hours to obtain an organosilicon-modified polyimide solution. The obtained organosilicon-modified polyimide solution was cast and dried on a glass plate to form a film to obtain an organosilicon-modified PI substrate.

[0051] Comparative Example 1

[0052] A method for preparing an acrylic pressure-sensitive adhesive comprises the following steps:

[0053] (1) Acrylic acid, methyl methacrylate, butyl acrylate and hydroxyethyl acrylate are added to a toluene solvent in a mass ratio of 1:1:1:1, and dibenzoyl peroxide initiator is added under nitrogen protection, heated to 70-75° C., and polymerized for 4 hours to obtain an acrylic acid prepolymer solution with a solid content of 40%.

[0054] (2) coating the acrylic prepolymer solution obtained in step (1) on one side of a polyimide substrate (a PI substrate conventionally prepared from pyromellitic anhydride and diaminodiphenyl ether monomers), heating and drying in a vacuum drying oven to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain an acrylic single-sided adhesive.

[0055] Comparative Example 2

[0056] A method for preparing an acrylic pressure-sensitive adhesive comprises the following steps:

[0057] (1) Acrylic acid, methyl methacrylate, butyl acrylate and hydroxyethyl acrylate are added to a toluene solvent in a mass ratio of 1:1:1:1, and dibenzoyl peroxide initiator is added under nitrogen protection, heated to 70-75° C., and polymerized for 4 hours to obtain an acrylic acid prepolymer solution with a solid content of 40%.

[0058] (2) Add toluene diisocyanate (TDI) crosslinking agent to the acrylic prepolymer solution of step (2) for crosslinking reaction at 70-75°C for 2 hours to obtain acrylic pressure-sensitive adhesive solution. The added mass of TDI is 25% of the solid content in the acrylic prepolymer solution.

[0059] (3) coating the acrylic pressure-sensitive adhesive solution obtained in step (2) on one side of a polyimide substrate (a PI substrate conventionally prepared from pyromellitic anhydride and diaminodiphenyl ether monomers), heating and drying in a vacuum drying oven to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain an acrylic single-sided adhesive.

[0060] 1. The peel strength (GB / T 2792-2014), 180°C stickiness (GB / T 4851-2014) and high temperature resistance (the pressure-sensitive adhesive sample was evenly attached to a stainless steel plate, placed in an oven and baked at 260°C for 30 min, taken out and cooled to room temperature, and then the tape was slowly peeled off to observe the residual adhesive on the surface of the stainless steel plate) of the acrylic single-sided adhesive obtained in the above Examples 1 to 4 and Comparative Examples 1 to 2 were tested. The results are shown in Table 1 below.

[0061] Table 1

[0062]

[0063]

[0064] *A large amount of residual adhesive means that the residual adhesive area accounts for more than 20% of the total area of ​​the pressure-sensitive adhesive sample; **A small amount of residual adhesive means that the residual adhesive area accounts for 5-10% of the total area of ​​the pressure-sensitive adhesive sample.

[0065] The results of Comparative Example 1 and the Example show that the high temperature holding performance and high temperature performance of the acrylic pressure-sensitive adhesive without cross-linking reaction are significantly reduced. The results of Comparative Example 2 and the Example show that the peel strength of the acrylic pressure-sensitive adhesive obtained by using conventional toluene diisocyanate cross-linking agent is significantly reduced, and the high temperature holding performance and high temperature performance are reduced to a certain extent.

[0066] 2. The high temperature performance (5% weight loss temperature), tensile strength, elongation at break and moisture-heat stability (moisture absorption rate measured after immersion in 80°C hot water for 24 hours) of the conventional PI substrate of Example 1 and the organosilicon-modified PI substrate of Example 5 are shown in Table 2 below.

[0067] Table 2

[0068] Test sample 5% weight loss temperature, ℃ Tensile strength, MPa Elongation at break, % Moisture absorption rate, % Example 1 524 165 55 1.7 Example 5 568 157 89 0.5

[0069] From the results in Table 2, it can be concluded that the use of silicone-modified PI substrate can further enhance the high temperature resistance, moisture resistance and flexibility of the PI base film.

[0070] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a high temperature resistant acrylic pressure-sensitive adhesive, characterized in that: The method comprises the following preparation steps: (1) subjecting a cyclosiloxane monomer, isocyanate propylmethyldimethoxysilane and a methylsilane end-capping agent to a polymerization reaction in the presence of a catalyst and anhydrous conditions to obtain an isocyanate polysiloxane; (2) adding acrylic acid monomer, acrylic ester monomer and functional monomer into an organic solvent, adding an initiator under nitrogen protection, heating and polymerization reaction, and obtaining an acrylic acid prepolymer solution; (3) adding the isocyanate polysiloxane obtained in step (1) to the acrylic prepolymer solution in step (2) to carry out a cross-linking reaction at a temperature of 100 °C to obtain an acrylic pressure-sensitive adhesive solution; (4) coating the acrylic pressure-sensitive adhesive solution obtained in step (3) on one side or both sides of the polyimide substrate, heating and drying to solidify to obtain a pressure-sensitive adhesive layer, and then coating the surface of the pressure-sensitive adhesive layer with a release film to obtain a high-temperature resistant acrylic single-sided adhesive or double-sided adhesive.

2. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 1, characterized in that: In step (1), the cyclosiloxane monomer is octamethylcyclotetrasiloxane or a dimethylsiloxane mixed ring; the methylsilane end-capping agent is hexamethyldisiloxane, methoxytrimethylsilane or trimethylchlorosilane; the mass ratio of the cyclosiloxane monomer, isocyanatepropylmethyldimethoxysilane and methylsilane end-capping agent added is 100:10-40:1-10.

3. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 1, characterized in that: The catalyst in step (1) is sodium siliconate or potassium siliconate; the polymerization reaction temperature is 100-140° C., and the polymerization reaction time is 2-8 hours.

4. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 1, characterized in that: The acrylic acid monomer in step (2) is one or both of acrylic acid and methacrylic acid; the acrylic acid ester monomer is one or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate, and lauryl methacrylate; the functional monomer is one or more of acrylamide, acrylonitrile, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and styrene; and the mass ratio of the acrylic acid monomer, the acrylic acid ester monomer, and the functional monomer is 1:1-3:0.5-2.

5. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 1, characterized in that: The organic solvent in step (2) is one or more of toluene, ethyl acetate, N,N-dimethylformamide, and N,N-dimethylacetamide; the initiator is dibenzoyl peroxide or azobisisobutyronitrile; the temperature of the heating polymerization reaction is 60-80° C., and the time is 3-6 hours.

6. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 1, characterized in that: The amount of the isocyanate polysiloxane added in step (3) is 10-50% of the total mass of the acrylic monomer, acrylate monomer and functional monomer in step (2); the temperature of the heat preservation cross-linking reaction is 60-80° C. and the time is 1-3 hours.

7. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 1, characterized in that: The PI substrate described in step (4) refers to an organosilicon-modified PI substrate prepared by the following method: The dianhydride monomer, diamine monomer, dehydrating agent and catalyst are added to an organic solvent and dissolved evenly, the temperature is raised to 80-150°C for prepolymerization reaction, and then isocyanate polysiloxane is added to continue the heat preservation polymerization reaction, and the obtained silicone-modified polyimide solution is dried on a substrate to form a film to obtain a silicone-modified PI substrate.

8. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 7, characterized in that: The dianhydride monomer is pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxylic acid)hexafluoropropane dianhydride, 4,4'-phenylenedioxydiphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride or 3,3',4,4'-diphenylethertetracarboxylic dianhydride; the diamine monomer is terephthalic acid The invention relates to a novel nanostructured carbon foam, a ...

9. The method for preparing a high temperature resistant acrylic pressure sensitive adhesive according to claim 7, characterized in that: The molar ratio of the dianhydride monomer and the diamine monomer added is 1.2-1.5:1, and the time of the prepolymerization reaction is 2-6 hours; the amount of the isocyanate polysiloxane added is 20-60% of the total mass of the dianhydride monomer and the diamine monomer, and the time of the heat preservation polymerization reaction is 2-6 hours.

10. A high temperature resistant acrylic pressure sensitive adhesive, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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