A method for preparing composite silica gel OCA film for touch screen

Abstract

The invention relates to the technical field of silicone OCA and discloses a method for preparing a composite silicone OCA adhesive film for a touch screen. Methyl vinyl silicone rubber, methyl MQ silicone resin, modified hydrogen-containing silicone oil, polyether tackifier, and silicon-hydrogen crosslinking agent ethyl platinum catalyst are mixed to form a silicone adhesive liquid, and then the silicone adhesive liquid is evenly coated on a release surface of a heavy release film to form an adhesive film, and finally a light release film is attached to the other side of the adhesive film to obtain the composite silicone OCA adhesive film, wherein the addition of the modified hydrogen-containing silicone oil and the polyether tackifier can effectively enhance the aging resistance and bonding performance of the composite silicone OCA adhesive film, so that the composite silicone OCA adhesive film is easier to adhere.

Description

Technical Field

[0001] The invention relates to the technical field of silica gel OCA, and in particular to a method for preparing a composite silica gel OCA film for a touch screen. Background Art

[0002] With the continuous updating of electronic products such as mobile phones and computers, traditional button-operated electronic products are gradually being eliminated, and are being replaced by more convenient touch-operated ones. Therefore, in recent years, all kinds of electronic products have begun to be equipped with touch screens. Conventional touch screens are mainly composed of liquid crystal panels and backlight modules, among which the backlight modules are mainly composed of light sources, reflectors, light guide plates, diffusers and brightness enhancement films. In recent years, display modules have developed rapidly, and correspondingly, the functional requirements for reflectors are getting higher and higher. Therefore, it is often necessary to make some microscopic treatments on the surface of the reflector, which also makes conventional OCA adhesives unable to meet the bonding and lamination requirements. Therefore, the development of new OCA films is urgent.

[0003] Compared with conventional acrylic OCA films, organic silica gel has more excellent properties, such as good moisture resistance and chemical inertness, as well as good weather resistance and biocompatibility. The Chinese invention patent with application number CN202011617956.8 discloses an organic silica gel adhesive, organic silica OCA and its preparation method and application. By adding a modified macromolecular coupling agent with a specific structure to the organic silica gel adhesive formula, the molecules have a higher bonding strength, thereby improving the overall modulus of the OCA colloid and maintaining good adhesion of the colloid. Therefore, organic silica gel can be used as an optical OCA film for bonding reflective sheets. However, electronic products are prone to heat during use, especially in hot summer. Long-term use at high temperatures will cause thermal oxidation aging of the film, and then loss of adhesion.

[0004] Based on this, the present invention provides a composite silicone OCA film, which has good aging resistance and high bonding performance, can be directly used in the bonding of reflective sheets, and is conducive to the further application and development of touch screens. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a composite silicone OCA film for a touch screen, which solves the problem that the silicone film is easy to age in a high temperature environment and has poor bonding strength.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a composite silica gel OCA film for a touch screen comprises the following steps:

[0008] Step 1: 50-60 parts of methyl vinyl silicone rubber, 20-40 parts of methyl MQ silicone resin and 200-300 parts of toluene are mixed, placed in a kneader for kneading for 4-8 hours, and then placed in a temperature environment of 80-90° C. for treatment for 2-4 hours to obtain a silica gel base material;

[0009] Step 2: Pour the silicone base material, 5-10 parts of modified hydrogen-containing silicone oil, 1-5 parts of polyether tackifier and 0.5-3 parts of silicon-hydrogen crosslinking agent into a mixer, set the stirring speed to 100-200r / min, stir thoroughly for 20-30min to obtain a film base material;

[0010] Step 3: Add 0.01-0.03 parts of catalyst to the film base material, stir for 20-40min, filter with a 5um filter, let stand to defoam, and obtain a silica gel solution;

[0011] Step 4: Use a glue coating machine to apply the silicone glue liquid to the release surface of the heavy release film, place it at a temperature of 80-100°C to cure, and form a film with a thickness of 30-50um. Attach the light release film to the other side of the film, roll it up, and package it to obtain a composite silicone OCA film;

[0012] The modified hydrogen-containing silicone oil is prepared by introducing an antioxidant into the molecular chain of the hydrogen-containing silicone oil;

[0013] The polyether tackifier is prepared by introducing active epoxy groups into the allyl polyether molecular chain.

[0014] Furthermore, the molecular weight of the methyl vinyl silicone rubber is 450,000-850,000, and the vinyl content is 0.16-0.18%; the M / Q of the methyl MQ silicone resin is 0.6-1.0; the silicon hydrogen crosslinking agent is Dow Corning 7028; and the catalyst is a platinum catalyst.

[0015] Through the above technical scheme, the olefin groups in the structures of methyl vinyl silicone rubber, methyl MQ silicone resin and polyether tackifier can undergo silylation reaction with the Si-H bonds in the silylation crosslinking agent and the modified hydrogen-containing silicone oil structure. Therefore, under the action of a platinum catalyst, it can be cured at high temperature to form a composite silicone OCA film with a three-dimensional cross-linked network structure.

[0016] Furthermore, the preparation method of the modified hydrogen-containing silicone oil is specifically as follows:

[0017] The hydrogen-containing silicone oil, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and toluene are mixed and stirred evenly, and then the catalyst is added dropwise to mix evenly. The system is placed in a temperature environment of 80-100°C, stirred for 12-18 hours, and then the solvent is evaporated and cooled naturally to obtain the modified hydrogen-containing silicone oil.

[0018] Furthermore, the molecular weight of the hydrogen-containing silicone oil is 500-750, the hydrogen content is 0.18-0.75%, and the viscosity at room temperature is 80-120 mm 2 / s.

[0019] Furthermore, the mass ratio of the hydrogen-containing silicone oil to 2,2'-methylenebis(4-methyl-6-tert-butylphenol) is 10:0.2-0.5.

[0020] Furthermore, the catalyst is trifluoroacetic acid, and the amount of trifluoroacetic acid added is 0.2-0.5% of the total mass of hydrogen-containing silicone oil and 2,2'-methylenebis(4-methyl-6-tert-butylphenol).

[0021] Through the above technical scheme, the hydrogen-containing silicone oil structure contains Si-H bonds, which can react with the phenol group in the structure of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) under the action of the catalyst trifluoroacetic acid. By controlling the dosage ratio of the materials, hindered phenol antioxidants can be introduced into the hydrogen-containing silicone oil structure, while preserving some Si-H bonds to obtain modified hydrogen-containing silicone oil.

[0022] Furthermore, the preparation method of the polyether tackifier comprises the following steps:

[0023] Step 1: Mix allyl polyether and toluene, add maleic anhydride and stir evenly, place the system at a temperature of 60-80°C, stir for 12-24 hours, remove toluene, discharge, and obtain acidified allyl polyether;

[0024] Step 2: Mix the acidified allyl polyether and tetrahydrofuran, add 1,3-diglycidyl ether glycerol and the accelerator, mix well, pass nitrogen protection, stir at room temperature for 4-12 hours, evaporate the solvent, cool naturally, discharge, and obtain a polyether tackifier.

[0025] Furthermore, in the first step, the molecular weight of the allyl polyether is 300-900, the hydroxyl value is 37-53 mg KOH / g, and the double bond value is 0.5-2 mmol / g.

[0026] Furthermore, in the second step, the promoter is p-toluenesulfonic acid.

[0027] Furthermore, in the second step, the flow rate of the nitrogen is 0.6-0.8 L / min.

[0028] Through the above technical scheme, the end of the allyl polyether molecular chain contains active hydroxyl groups, which can undergo a ring-opening condensation reaction with maleic anhydride, and an active carboxyl group is introduced into the end of the allyl polyether molecular chain to obtain an acidified allyl polyether. Under the action of p-toluenesulfonic acid, the active hydroxyl groups in the glycerol structure of 1,3-dioxyglycerol ether can undergo an esterification reaction with the carboxyl group at the end of the acidified allyl polyether molecular chain, thereby modifying two equivalent epoxy groups at the end of the allyl polyether molecular chain to obtain a polyether thickener.

[0029] Beneficial effects of the present invention:

[0030] (1) The present invention adopts hydrogen-containing silicone oil grafted with an antioxidant as an additive. After curing, a large amount of antioxidant can be introduced into the composite silica gel OCA film, so that the antioxidant exists in the composite silica gel OCA film in the form of chemical bonds, thereby avoiding the precipitation and migration that may be caused by pure physical addition, effectively enhancing the aging resistance of the composite silica gel OCA film, and the antioxidant structure contains a rigid benzene ring, which can improve the modulus of the composite silica gel OCA film and avoid damage, deformation and the like during production or use.

[0031] (2) In the process of preparing the composite silicone OCA film, the present invention adds a polyether thickener, and the polyether thickener contains active olefin groups and active epoxy groups as end groups, wherein the active olefin groups can participate in the curing reaction of the composite silicone, and introduce a large number of active epoxy groups into the composite silicone OCA film. Since the epoxy groups are highly active, they can have good adhesion promoting properties for the composite silicone OCA film. In addition, the polyether molecular chain contains a large number of ether bonds, which can generate hydrogen bonds with the adhered substrate, further improving its bonding strength, making the composite silicone OCA film easier to adhere.

[0032] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0034] Figure 1 IR spectra of hydrogen-containing silicone oil and modified hydrogen-containing silicone oil in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] Preparation of modified hydrogen-containing silicone oil

[0038] 5 g of hydrogenated silicone oil, 0.1 g of 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and toluene were mixed and stirred, and then 0.02 g of trifluoroacetic acid was added dropwise and mixed. The system was placed in a temperature environment of 90°C, stirred for 16 hours, and then the solvent was evaporated and cooled naturally to obtain modified hydrogenated silicone oil; wherein the hydrogenated silicone oil had a molecular weight of 650, a hydrogen content of 0.6%, and a viscosity of 100 mm at room temperature. 2 / s.

[0039] Infrared characterization of hydrogenated silicone oil and modified hydrogenated silicone oil is carried out. The test results are shown in Figure 1 ,Depend on Figure 1 It can be seen that compared with hydrogen-containing silicone oil, modified hydrogen-containing silicone oil has a -1 The absorption peak of phenol appears at 2850~3000cm -1 The absorption peak area of ​​methyl and ethyl at 2100-2200 cm -1 The absorption peak area of ​​Si-H bond at 1589 cm -1 1462cm -1 The absorption peak of the benzene ring appears at , which is due to the reaction between the Si-H bond in the hydrogen silicone oil structure and the phenolic hydroxyl group in the 2,2'-methylenebis(4-methyl-6-tert-butylphenol) structure, which consumes part of the Si-H bond and introduces the hindered phenol antioxidant.

[0040] Example 2

[0041] Preparation of polyether tackifier

[0042] Step 1: 10 mL of allyl polyether was mixed with toluene, 1.5 g of maleic anhydride was added and stirred evenly, the system was placed at a temperature of 60° C., and after stirring for 24 hours, toluene was removed and the material was discharged to obtain acidified allyl polyether, wherein the molecular weight of the allyl polyether was 750, the hydroxyl value was 50 mg KOH / g, and the double bond value was 1.6 mmol / g;

[0043] Accurately weigh 1g of allyl polyether sample, soak it in a 0.1M calcium acetate solution, shake it thoroughly for 30 minutes, then draw 20mL of the solution, add 0.1mL of cresol red and 0.1mL of thymol blue as indicators, and titrate with a 0.1M sodium hydroxide standard solution until the color of the solution changes. Stop the titration and do a blank control experiment at the same time. Use the formula Calculate the carboxyl content in the sample, where V0 is the volume of sodium hydroxide standard solution consumed in the blank experiment, mL; V is the volume of sodium hydroxide standard solution consumed in the titration sample, mL; C is the concentration of sodium hydroxide standard solution, mol / L; M is the mass of the sample, g; after calculation, the carboxyl content in the sample is 0.1215%.

[0044] Step 2: Mix 4 mL of acidified allyl polyether and tetrahydrofuran, add 1 g of 1,3-diepoxyglycerol ether glycerol and p-toluenesulfonic acid and mix well, set the nitrogen flow rate to 0.6 L / min, pass nitrogen protection, stir at room temperature for 9 hours, evaporate the solvent, cool naturally, discharge, and obtain a polyether thickener.

[0045] Accurately weigh 0.5g of polyether tackifier sample, mix with 50mL of 15% tetraethylammonium bromide acetic acid solution and 0.1mL of crystal violet indicator, let stand for 4h, and titrate with 0.1M perchloric acid-glacial acetic acid standard solution until the solution changes color. At the same time, do a blank control test and use the formula Calculate the epoxy group content of the sample, where V1 is the volume of perchloric acid-acetic acid standard solution consumed in the blank experiment, mL; V2 is the volume of perchloric acid-acetic acid standard solution consumed by the titration sample, mL; c is the concentration of perchloric acid-acetic acid standard solution, mol / L; m is the mass of the sample, g; after calculation, the epoxy group content W in the sample is 0.517 mmol / g.

[0046] Example 3

[0047] Preparation of composite silica gel OCA film

[0048] Step 1: 55 parts of methyl vinyl silicone rubber, 30 parts of methyl MQ silicone resin and 260 parts of toluene are mixed, placed in a kneader for 6 hours, and then placed in a temperature environment of 85° C. for 3 hours to obtain a silica gel base material, wherein the molecular weight of the methyl vinyl silicone rubber is 650,000, the vinyl content is 0.18%, and the M / Q of the methyl MQ silicone resin is 0.8;

[0049] Step 2: Pour the silicone base material, 8 parts of modified hydrogen-containing silicone oil, 2 parts of polyether tackifier and 2.4 parts of Dow Corning 7028 silicon hydrogen crosslinking agent into a blender, set the stirring speed to 150 r / min, and stir thoroughly for 25min to obtain a film base material;

[0050] Step 3: Add 0.02 parts of platinum catalyst to the film base material, stir for 30 min, filter with a 5um filter, let stand to defoam, and obtain a silica gel solution;

[0051] Step 4: Use a glue coating machine to apply the silicone glue liquid to the release surface of the heavy release film, place it at 90°C to cure, to form a 40um thick film, attach the light release film to the other side of the film, roll it up, and package it to obtain a composite silicone OCA film.

[0052] The preparation method of the modified hydrogen-containing silicone oil and the polyether tackifier is the same as that in Example 1.

[0053] Comparative Example 1

[0054] Preparation of composite silica gel OCA film

[0055] Step 1: 55 parts of methyl vinyl silicone rubber, 30 parts of methyl MQ silicone resin and 260 parts of toluene are mixed, placed in a kneader for 6 hours, and then placed in a temperature environment of 85° C. for 3 hours to obtain a silica gel base material, wherein the molecular weight of the methyl vinyl silicone rubber is 650,000, the vinyl content is 0.18%, and the M / Q of the methyl MQ silicone resin is 0.8;

[0056] Step 2: Pour the silica gel base material, 8 parts of modified hydrogen-containing silicone oil and 2.4 parts of Dow Corning 7028 silane crosslinking agent into a blender, set the stirring speed to 150 r / min, and stir thoroughly for 25min to obtain a film base material;

[0057] Step 3: Add 0.02 parts of platinum catalyst to the film base material, stir for 30 min, filter with a 5um filter, let stand to defoam, and obtain a silica gel solution;

[0058] Step 4: Use a glue coating machine to apply the silicone glue liquid to the release surface of the heavy release film, place it at 90°C to cure, to form a 40um thick film, attach the light release film to the other side of the film, roll it up, and package it to obtain a composite silicone OCA film.

[0059] The preparation method of the modified hydrogen-containing silicone oil is the same as that in Example 1.

[0060] Comparative Example 2

[0061] Step 1: 55 parts of methyl vinyl silicone rubber, 30 parts of methyl MQ silicone resin and 260 parts of toluene are mixed, placed in a kneader for 6 hours, and then placed in a temperature environment of 85° C. for 3 hours to obtain a silica gel base material, wherein the molecular weight of the methyl vinyl silicone rubber is 650,000, the vinyl content is 0.18%, and the M / Q of the methyl MQ silicone resin is 0.8;

[0062] Step 2: Pour the silicone base material, 2 parts of polyether tackifier and 2.4 parts of Dow Corning 7028 silane crosslinking agent into a blender, set the stirring speed to 150 r / min, and stir thoroughly for 25min to obtain a film base material;

[0063] Step 3: Add 0.02 parts of platinum catalyst to the film base material, stir for 30 min, filter with a 5um filter, let stand to defoam, and obtain a silica gel solution;

[0064] Step 4: Use a glue coating machine to apply the silicone glue liquid to the release surface of the heavy release film, place it at 90°C to cure, to form a 40um thick film, attach the light release film to the other side of the film, roll it up, and package it to obtain a composite silicone OCA film.

[0065] The preparation method of the polyether tackifier is the same as that in Example 1.

[0066] Comparative Example 3

[0067] Step 1: 55 parts of methyl vinyl silicone rubber, 30 parts of methyl MQ silicone resin and 260 parts of toluene are mixed, placed in a kneader for 6 hours, and then placed in a temperature environment of 85° C. for 3 hours to obtain a silica gel base material, wherein the molecular weight of the methyl vinyl silicone rubber is 650,000, the vinyl content is 0.18%, and the M / Q of the methyl MQ silicone resin is 0.8;

[0068] Step 2: Pour the silica gel base material and 2.4 parts of Dow Corning 7028 silane crosslinking agent into a blender, set the stirring speed to 150 r / min, and stir thoroughly for 25min to obtain a film base material;

[0069] Step 3: Add 0.02 parts of platinum catalyst to the film base material, stir for 30 min, filter with a 5um filter, let stand to defoam, and obtain a silica gel solution;

[0070] Step 4: Use a glue coating machine to apply the silicone glue liquid to the release surface of the heavy release film, place it at 90°C to cure, to form a 40um thick film, attach the light release film to the other side of the film, roll it up, and package it to obtain a composite silicone OCA film.

[0071] Performance Testing

[0072] The light release surface of the composite silica gel OCA film prepared in Example 3 of the present invention and Comparative Examples 1 to 3 was peeled off, and 0.025MM transparent PET was used for transfer lamination, and the samples were cut into sizes that met the specifications and affixed to the reflective sheet, and the following performance tests were performed:

[0073] The initial adhesion of the sample was tested with reference to the national standard GB / T 4852-2002 "Test method for initial adhesion of pressure-sensitive adhesive tape (rolling ball method)"; the lasting adhesion of the sample was tested with reference to the national standard GB / T 4851-2014 "Test method for persistent adhesion of adhesive tape"; the light peeling release force and heavy peeling release force of the sample were tested with reference to the national standard GB / T2792-2014 "Test method for peel strength of adhesive tape"; the modulus of the sample was tested with reference to the standard JB / T 6544-1993 "Test method for tensile and flexural modulus of plastics"; the sample was placed in an environment of 65°C and 95% humidity, aged for 240 hours, and then the initial adhesion and lasting adhesion tests were performed again. The test results are shown in the following table:

[0074]

[0075] It can be seen from the above table that the composite silica gel OCA film prepared in Example 3 of the present invention has good bonding performance and aging resistance, and at the same time shows a higher modulus and has excellent comprehensive performance.

[0076] The composite silica gel OCA film prepared in Comparative Example 1 was not modified with a polyether tackifier, so the bonding performance was poor. However, due to the use of modified hydrogenated silicone oil, it still exhibited good aging resistance and modulus.

[0077] The composite silica gel OCA film prepared in Comparative Example 2 did not use modified hydrogen-containing silicone oil, but because a polyether tackifier was used, although it showed good bonding performance, its heat resistance and modulus were not good.

[0078] The composite silica gel OCA film prepared in Comparative Example 3 has the worst performance in all aspects because it does not use modified hydrogen-containing silicone oil and polyether tackifier.

[0079] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0080] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite silica gel OCA film for a touch screen, characterized in that: The following steps are involved: Step 1: 50-60 parts of methyl vinyl silicone rubber, 20-40 parts of methyl MQ silicone resin and 200-300 parts of toluene are mixed, placed in a kneader for kneading for 4-8 hours, and then placed in a temperature environment of 80-90° C. for treatment for 2-4 hours to obtain a silica gel base material; Step 2: Pour the silicone base material, 5-10 parts of modified hydrogen-containing silicone oil, 1-5 parts of polyether tackifier and 0.5-3 parts of silicon-hydrogen crosslinking agent into a mixer, set the stirring speed to 100-200r / min, stir thoroughly for 20-30min, and obtain the film base material; Step 3: Add 0.01-0.03 parts of catalyst to the film base material, stir for 20-40 minutes, filter with a 5um filter, let stand to defoam, and obtain a silica gel solution; Step 4: Use a glue coating machine to apply the silicone glue liquid to the release surface of the heavy release film, place it at a temperature of 80-100°C to cure, and form a film with a thickness of 30-50um. Attach the light release film to the other side of the film, roll it up, and package it to obtain a composite silicone OCA film; The modified hydrogen-containing silicone oil is prepared by introducing an antioxidant into the molecular chain of the hydrogen-containing silicone oil; The preparation method of the modified hydrogen-containing silicone oil is specifically as follows: The hydrogen-containing silicone oil, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and toluene are mixed and stirred, and then the catalyst is added dropwise and mixed, and the system is placed in a temperature environment of 80-100°C, stirred for 12-18 hours, and then the solvent is evaporated and cooled naturally to obtain a modified hydrogen-containing silicone oil; The polyether tackifier is prepared by introducing active epoxy groups into the allyl polyether molecular chain; The preparation method of the polyether tackifier comprises the following steps: Step 1: Mix allyl polyether and toluene, add maleic anhydride and stir evenly, place the system at a temperature of 60-80°C, stir for 12-24 hours, remove toluene, discharge, and obtain acidified allyl polyether; Step 2: Mix the acidified allyl polyether and tetrahydrofuran, add 1,3-diglycidyl ether glycerol and the accelerator, mix well, pass nitrogen protection, stir at room temperature for 4-12 hours, evaporate the solvent, cool naturally, discharge, and obtain a polyether tackifier.

2. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: The molecular weight of the methyl vinyl silicone rubber is 450,000-850,000, and the vinyl content is 0.16-0.18%; the M / Q of the methyl MQ silicone resin is 0.6-1.0; the silicon hydrogen crosslinking agent is Dow Corning 7028; and the catalyst is a platinum catalyst.

3. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: The molecular weight of the hydrogen-containing silicone oil is 500-750, the hydrogen content is 0.18-0.75%, and the viscosity at room temperature is 80-120 mm 2 / s.

4. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: The mass ratio of the hydrogen-containing silicone oil to 2,2'-methylenebis(4-methyl-6-tert-butylphenol) is 10:0.2-0.

5.

5. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: The catalyst is trifluoroacetic acid, and the amount of trifluoroacetic acid added is 0.2-0.5% of the total mass of hydrogen-containing silicone oil and 2,2'-methylenebis(4-methyl-6-tert-butylphenol).

6. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: In the first step, the molecular weight of the allyl polyether is 300-900, the hydroxyl value is 37-53 mg KOH / g, and the double bond value is 0.5-2 mmol / g.

7. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: In the second step, the promoter is p-toluenesulfonic acid.

8. The method for preparing a composite silica gel OCA film for a touch screen according to claim 1, characterized in that: In the second step, the flow rate of the nitrogen is 0.6-0.8 L / min.

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