OCA optical adhesive and preparation method thereof and touch screen

Abstract

The present invention relates to the field of optical adhesive technology, and in particular to an OCA optical adhesive, a preparation method thereof, and a touch screen. The OCA optical adhesive comprises the following components by weight: 85-95 parts of a modified silicone prepolymer, 5-15 parts of a crosslinking agent, 0.01-0.1 parts of a first photoinitiator, and 0.1-2 parts of a functional additive; the modified silicone prepolymer is mainly prepared by the following components by weight: 30-60 parts of a terminal vinyl siloxane, 40-70 parts of a monomer, 0.01-1 parts of a second photoinitiator, and 0.002-0.2 parts of a chain transfer agent; the functional additive comprises: (a) tetrabutylammonium bromide; (b) other optional additives, the other additives being selected from at least one of aluminum acetylacetonate and triphenylphosphine. The present invention uses silicone to modify the main resin, and at the same time introduces a specific functional additive into the system, which can significantly improve the bonding performance and ensure the lamination performance when bonding a low surface energy substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of optical adhesives, and in particular to an OCA optical adhesive and a preparation method thereof, and a touch screen. Background Art

[0002] With the development of the domestic electronics industry, electronic touch displays have become widely popular. OCA optical adhesive, as a bonding material for touch screens, can be used as an important material for filling and bonding.

[0003] Acrylic system is the main system in optical adhesive. It is made by mixing resin, functional monomer, diluent monomer, photoinitiator and additive into glue, and finally forming a film and curing. Acrylic system glue has strong adhesion to PET and glass substrates, but has low adhesion to substrates with low surface energy, making it difficult to bond effectively. In the prior art, in order to improve the bonding performance of OCA optical adhesive to low surface energy substrates, a variety of substances are introduced, but the improvement of bonding performance is limited.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One object of the present invention is to provide an OCA optical adhesive having excellent bonding properties to substrates with low surface energy, and having good high temperature resistance and bonding stability.

[0006] Another object of the present invention is to provide a method for preparing OCA optical adhesive.

[0007] Another object of the present invention is to provide a touch screen.

[0008] In order to achieve the above-mentioned object of the present invention, the present invention provides an OCA optical adhesive on the one hand, comprising the following components in parts by weight: 85-95 parts of a modified silicone prepolymer, 5-15 parts of a crosslinking agent, 0.01-0.1 parts of a first photoinitiator and 0.1-2 parts of a functional additive;

[0009] The modified silicone prepolymer is mainly prepared from the following components by weight: 30-60 parts of vinyl-terminated siloxane, 40-70 parts of monomer, 0.01-1 parts of second photoinitiator and 0.002-0.2 parts of chain transfer agent;

[0010] The functional additives include:

[0011] (a) Tetrabutylammonium bromide;

[0012] (b) other optional auxiliary agents, wherein the other auxiliary agents are selected from at least one of aluminum acetylacetonate and triphenylphosphine.

[0013] In a specific embodiment of the present invention, the mass ratio of the tetrabutylammonium bromide to the other auxiliary agents is 3: (1-9).

[0014] In a specific embodiment of the present invention, the mass ratio of the terminal vinyl siloxane in the modified silicone prepolymer to the functional additive is (50-200):1.

[0015] In a specific embodiment of the present invention, the crosslinking agent includes at least one of 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, cyclohexanedimethanol diacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane acrylate and dipentaerythritol hexaacrylate.

[0016] In a specific embodiment of the present invention, the first photoinitiator and the second photoinitiator each independently include at least one of photoinitiator TPO, photoinitiator 184 and photoinitiator 1173.

[0017] In a specific embodiment of the present invention, the viscosity of the modified silicone prepolymer is 2500-4000 cps.

[0018] In a specific embodiment of the present invention, the vinyl-terminated siloxane is methyl vinyl polysiloxane. Further, the viscosity of the vinyl-terminated siloxane is 200-1000 cps.

[0019] In a specific embodiment of the present invention, the monomer includes at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, vinyl acetate, acrylamide, methyl methacrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, maleic anhydride, isobutyl acrylate, 2-phenoxyethyl acrylate and 4-acryloylmorpholine.

[0020] In a specific embodiment of the present invention, the chain transfer agent includes at least one of ethyl mercaptan, butyl mercaptan, dodecyl mercaptan and benzene mercaptan.

[0021] Another aspect of the present invention provides a method for preparing any one of the above-mentioned OCA optical adhesives, comprising the following steps: mixing the components in proportion, and then ultraviolet curing to form the mixture.

[0022] In a specific embodiment of the present invention, in the UV curing, the UV wavelength is 200-400 nm, and the UV energy is 600-1000 mj / cm 2 .

[0023] Another aspect of the present invention provides a touch screen, comprising any one of the above-mentioned OCA optical adhesives.

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

[0025] (1) The present invention uses organic silicon to modify the main resin, thereby reducing the surface energy of the entire system and promoting the wetting of the system on the surface of the low surface energy substrate; at the same time, a specific functional additive is introduced into the system, and the functional additive can be arranged in a directional manner on the surface of the OCA optical adhesive, which significantly improves the bonding performance when bonding the low surface energy substrate and ensures the bonding performance;

[0026] (2) The preparation process of the OCA optical adhesive of the present invention is simple, safe, environmentally friendly, and low-cost, and has excellent economic benefits, production benefits, and environmental benefits. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0028] In one aspect, the present invention provides an OCA optical adhesive, comprising the following components by weight: 85-95 parts of a modified silicone prepolymer, 5-15 parts of a crosslinking agent, 0.01-0.1 parts of a first photoinitiator, and 0.1-2 parts of a functional additive;

[0029] The modified organic silicon prepolymer is mainly prepared from the following components by weight: 30-60 parts of terminal vinyl siloxane, 40-70 parts of monomer, 0.01-1 parts of second photoinitiator and 0.002-0.2 parts of chain transfer agent;

[0030] Functional additives include:

[0031] (a) Tetrabutylammonium bromide;

[0032] (b) other optional auxiliary agents, which are selected from at least one of aluminum acetylacetonate and triphenylphosphine.

[0033] The OCA optical adhesive of the present invention is prepared by combining multiple components. On the one hand, silicone is used to modify the main resin to reduce the surface energy of the entire system and promote the wetting of the system on the surface of the low surface energy substrate. At the same time, a certain amount of specific functional additives are introduced into the system. The functional additives can be directionally arranged on the surface of the OCA optical adhesive. When bonding the low surface energy substrate, the bonding performance is significantly improved and the bonding performance is guaranteed.

[0034] For example, in different embodiments, the amounts of the components used in the OCA optical adhesive can be as follows, measured by weight:

[0035] The amount of the modified silicone prepolymer can be 85 parts, 88 parts, 90 parts, 92 parts, 95 parts or a range consisting of any two of them;

[0036] The amount of the cross-linking agent can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts or a range consisting of any two of them;

[0037] The amount of the first photoinitiator can be 0.01 part, 0.05 part, 0.08 part, 0.1 part or a range consisting of any two thereof;

[0038] The dosage of the functional additive can be 0.1 part, 0.5 part, 0.8 part, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts or a range consisting of any two of them.

[0039] For example, in different embodiments, the amounts of the components used in the modified silicone prepolymer may be as follows, calculated by weight:

[0040] The amount of the vinyl-terminated siloxane can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts or a range consisting of any two of them;

[0041] The amount of the monomer can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts or a range consisting of any two of them;

[0042] The amount of the second photoinitiator can be 0.01 part, 0.05 part, 0.08 part, 0.1 part or a range consisting of any two thereof;

[0043] The amount of the chain transfer agent can be 0.002 parts, 0.01 parts, 0.1 parts, 0.2 parts or any combination thereof.

[0044] In a specific embodiment of the present invention, the mass ratio of tetrabutylammonium bromide to other auxiliary agents is 3: (1-9).

[0045] Among the functional additives used in the present invention, regulating the dosage of tetrabutylammonium bromide and other additives can further ensure the bonding performance of OCA optical adhesive to low surface energy substrates while ensuring bonding stability. For example, in different embodiments, the mass ratio of tetrabutylammonium bromide to other additives can be 3:1, 3:2, 1:1, 3:4, 3:5, 1:2, 3:7, 3:8, 1:3 or a range consisting of any two of them, preferably 3:(2-4).

[0046] In a specific embodiment of the present invention, the mass ratio of the terminal vinyl siloxane in the modified silicone prepolymer to the functional additive is (50-200):1.

[0047] Further regulating the mass ratio of the terminal vinyl siloxane part to the functional additive in the modified silicone prepolymer is helpful to improve the bonding performance of OCA optical adhesive to low surface energy substrates, ensure the bonding stability and avoid bubbles. Among them, the amount of terminal vinyl siloxane in the modified silicone prepolymer refers to the amount of raw material terminal vinyl siloxane used to prepare the corresponding modified silicone prepolymer. When the mass ratio of terminal vinyl siloxane to functional additive in the modified silicone prepolymer is too large, that is, the amount of terminal vinyl siloxane in the modified silicone prepolymer is too much, the polarity of the modified silicone prepolymer is significantly reduced, and the degree of directional arrangement of the polar groups and non-polar groups of the functional additive is low, resulting in insufficient improvement in the adhesion performance to low surface energy substrates; when the mass ratio of terminal vinyl siloxane to functional additive in the modified silicone prepolymer is too small, that is, the amount of terminal vinyl siloxane in the modified silicone prepolymer is too small, the polarity of the modified silicone prepolymer is not significantly reduced. Although the degree of directional arrangement of the polar groups and non-polar groups of the functional additive is good, the overall wettability of the resin matrix to the low surface energy substrate is insufficient, which also leads to insufficient improvement in the adhesion performance to the low surface energy substrate and poor bonding performance. For example, in different embodiments, the mass ratio of the terminal vinyl siloxane to the functional additive in the modified silicone prepolymer of the present invention can be 50:1, 60:1, 80:1, 100:1, 120:1, 150:1, 180:1, 200:1 or a range consisting of any two of them, for example, (80-180):1.

[0048] In a specific embodiment of the present invention, the crosslinking agent includes at least one of 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, cyclohexanedimethanol diacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane acrylate and dipentaerythritol hexaacrylate.

[0049] In a specific embodiment of the present invention, the first photoinitiator and the second photoinitiator each independently include at least one of photoinitiator TPO, photoinitiator 184 and photoinitiator 1173.

[0050] In a specific embodiment of the present invention, the viscosity of the modified silicone prepolymer is 2500-4000 cps. Further, the preparation of the modified silicone prepolymer includes: after the components are uniformly mixed, reacting under ultraviolet light until the viscosity reaches 2500-4000 cps, stopping the reaction, and obtaining the modified silicone prepolymer.

[0051] For example, in different embodiments, the viscosity of the modified silicone prepolymer can be 2500cps, 2800cps, 3000cps, 3200cps, 3500cps, 3800cps, 4000cps or any two thereof. The viscosity of the modified silicone prepolymer is within the above range, which can ensure the uniformity of mixing with other components and ensure that the system has a certain fluidity; on the other hand, it can regulate the degree of reaction so that the system is fully cured when preparing the OCA optical adhesive, thereby ensuring the strength of the OCA optical adhesive.

[0052] In actual operation, the preparation of modified silicone prepolymer is carried out under a protective atmosphere. For example, the uniformly mixed materials can be filled with nitrogen and then subjected to ultraviolet irradiation reaction under a nitrogen protective atmosphere.

[0053] In a specific embodiment of the present invention, the vinyl-terminated siloxane is methyl vinyl polysiloxane. Further, the viscosity of the vinyl-terminated siloxane is 200 to 1000 cps.

[0054] For example, in different embodiments, the viscosity of the vinyl-terminated siloxane of the present invention can be 200cps, 400cps, 500cps, 800cps, 1000cps or any two thereof. The present invention does not elaborate on the methylvinyl polysiloxane used, and any methylvinyl polysiloxane with a viscosity that meets the above requirements can be used.

[0055] In a specific embodiment of the present invention, the monomer includes at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, vinyl acetate, acrylamide, methyl methacrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, maleic anhydride, isobutyl acrylate, 2-phenoxyethyl acrylate and 4-acryloylmorpholine.

[0056] In a specific embodiment of the present invention, the chain transfer agent includes at least one of ethyl mercaptan, butyl mercaptan, dodecyl mercaptan and benzene mercaptan.

[0057] In a specific embodiment of the present invention, the OCA optical adhesive of the present invention is bonded in the form of an adhesive film between a coated glass with a water drop angle greater than 105° and a PET substrate, and is peeled at a speed of 300 mm / min. The peeling force at 25°C is ≥10N / 25mm, preferably ≥11N / 25mm, and more preferably ≥12N / 25mm; the peeling force at 85°C is ≥2.0N / 25mm, preferably ≥2.5N / 25mm, and more preferably ≥2.9N / 25mm.

[0058] Another aspect of the present invention provides a method for preparing any one of the above-mentioned OCA optical adhesives, comprising the following steps: mixing the components in proportion, and then ultraviolet curing to form the mixture.

[0059] In actual operation, the preparation of OCA optical adhesive may include: coating the mixed materials into a film, and then UV curing. OCA optical adhesive is in the form of an adhesive film, and the thickness can be 25 to 400 μm, and the thickness can be adjusted according to actual needs.

[0060] In a specific embodiment of the present invention, in UV curing, the UV wavelength is 200-400 nm, and the UV energy is 600-1000 mj / cm 2 For example, a high pressure mercury lamp may be used, but is not limited thereto, as long as it can initiate polymerization.

[0061] Another aspect of the present invention provides a touch screen, comprising any one of the above-mentioned OCA optical adhesives.

[0062] Example 1

[0063] This embodiment provides a method for preparing OCA optical adhesive, comprising the following steps:

[0064] (1) Take 45 parts of methyl vinyl polysiloxane (viscosity 400 cps), 35 parts of isooctyl acrylate, 7 parts of acrylic acid, 13 parts of 4-hydroxybutyl acrylate, 0.02 parts of dodecyl mercaptan and 0.1 parts of photoinitiator 184 by weight, mix them evenly, fill with nitrogen for 30 minutes, and irradiate with a mercury lamp to start polymerization. When the reaction viscosity reaches about 3000 cps, terminate the reaction to obtain a modified silicone prepolymer.

[0065] (2) Take 90 parts of the modified silicone prepolymer prepared in step (1), 10 parts of 1,6-hexanediol diacrylate, 0.2 parts of tetrabutylammonium bromide, 0.2 parts of triphenylphosphine, and 0.1 parts of photoinitiator TPO, by weight, stir evenly, degas, and then pour on a heavy release film, coat it into a film and attach a light release film, and cure it under a mercury lamp for 3 minutes to obtain an OCA optical adhesive film with a thickness of 175 μm.

[0066] Example 2

[0067] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, with the only difference being that the preparation of the modified silicone prepolymer in step (1) is different.

[0068] Step (1) of this embodiment comprises: taking 60 parts by weight of methyl vinyl polysiloxane (viscosity 400 cps), 25 parts of isooctyl acrylate, 5 parts of acrylic acid, 10 parts of 4-hydroxybutyl acrylate, 0.02 parts of dodecyl mercaptan, and 0.1 parts of photoinitiator 184, mixing them evenly, filling with nitrogen for 30 minutes, irradiating with a mercury lamp to start polymerization, and terminating the reaction when the reaction viscosity reaches about 3000 cps to obtain a modified silicone prepolymer.

[0069] Example 3

[0070] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, with the only difference being that the preparation of the modified silicone prepolymer in step (1) is different.

[0071] Step (1) of this embodiment includes: taking 30 parts by weight of methyl vinyl polysiloxane (viscosity 400 cps), 35 parts of isooctyl acrylate, 25 parts of hydroxyethyl acrylate, 10 parts of isobornyl acrylate, 0.02 parts of dodecyl mercaptan, and 0.1 parts of photoinitiator 184, mixing them evenly, filling with nitrogen for 30 minutes, irradiating with a mercury lamp to start polymerization, and terminating the reaction when the reaction viscosity reaches about 3000 cps to obtain a modified silicone prepolymer.

[0072] Example 4

[0073] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, the only difference being that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0074] In this embodiment, the amount of tetrabutylammonium bromide used is 0.4 parts, and the amount of triphenylphosphine used is 0.4 parts.

[0075] Example 5

[0076] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, the only difference being that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0077] In this embodiment, the amount of tetrabutylammonium bromide used is 0.1 part, and the amount of triphenylphosphine used is 0.1 part.

[0078] Example 6

[0079] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, the only difference being that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0080] In this embodiment, the amount of tetrabutylammonium bromide used is 0.05 parts, and the amount of triphenylphosphine used is 0.05 parts.

[0081] Example 7

[0082] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, the only difference being that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0083] In this embodiment, the amount of tetrabutylammonium bromide used is 1 part, and the amount of triphenylphosphine used is 1 part.

[0084] Example 8

[0085] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, the only difference being that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0086] In this embodiment, the amount of tetrabutylammonium bromide used is 0.3 parts, and the amount of triphenylphosphine used is 0.1 parts.

[0087] Example 9

[0088] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, the only difference being that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0089] In this embodiment, the amount of tetrabutylammonium bromide used is 0.1 parts, and the amount of triphenylphosphine used is 0.3 parts.

[0090] Example 10

[0091] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, except that in step (2), an equal weight of aluminum acetylacetonate is used to replace triphenylphosphine.

[0092] Embodiment 11

[0093] This embodiment refers to the preparation method of the OCA optical adhesive of Embodiment 1, except that triphenylphosphine is not included in step (2) and the amount of tetrabutylammonium bromide used is 0.4 parts.

[0094] Comparative Example 1

[0095] Comparative Example 1 refers to the method for preparing the OCA optical adhesive of Example 1, except that in step (2), an equal weight of acrylic prepolymer is used to replace the modified silicone prepolymer.

[0096] The preparation method of the acrylic prepolymer in Comparative Example 1 includes: taking 35 parts of isooctyl acrylate, 7 parts of acrylic acid, 13 parts of 4-hydroxybutyl acrylate, 0.01 parts of dodecyl mercaptan, and 0.05 parts of photoinitiator 184 by weight, mixing them evenly, filling with nitrogen for 30 minutes, irradiating with a mercury lamp to start polymerization, and terminating the reaction when the reaction viscosity reaches about 3000 cps to obtain an acrylic prepolymer.

[0097] Comparative Example 2

[0098] Comparative Example 2 refers to the preparation method of the OCA optical adhesive of Example 1, except that tetrabutylammonium bromide is not included in step (2), and the amount of triphenylphosphine used is 0.4 parts.

[0099] Comparative Example 3

[0100] Comparative Example 3 refers to the method for preparing the OCA optical adhesive of Example 1, except that in step (2), 0.4 parts of aluminum acetylacetonate are used to replace all of tetrabutylammonium bromide and triphenylphosphine.

[0101] Comparative Example 4

[0102] Comparative Example 4 refers to the method for preparing the OCA optical adhesive of Example 1, except that the amounts of tetrabutylammonium bromide and triphenylphosphine used in step (2) are different.

[0103] In Comparative Example 4, the amount of tetrabutylammonium bromide used was 1.2 parts, and the amount of triphenylphosphine used was 1.2 parts.

[0104] Experimental example

[0105] In order to compare and illustrate the performance differences of the OCA optical adhesives in different embodiments and comparative examples, the following tests were conducted respectively. The test results are shown in Table 1.

[0106] Peel force test: The OCA optical adhesive samples of each embodiment and comparative example were cut into 25 mm wide, and the light release film was removed and attached to a special coated glass with a dyne value lower than 24 and a water drop angle greater than 105° (Dongguan Jingtuo New Glass Technology Co., Ltd., model number jtx-230213-1). A 25 μm thick, 300 mm long, corona-treated PET was attached to the other side. The samples were peeled off at a speed of 300 mm / min, the test temperature of the oven was set, and 5 sets of data were tested according to the national standard to obtain the average value.

[0107] Environmental test application: The OCA optical adhesive of each embodiment and comparative example was respectively bonded to the cover plate and then to the LCM, and degassed. After standing for 24 hours, it was placed in a high temperature environment of 85°C and an environment of 85°C + 85%RH, respectively, to confirm whether there was bubble rebound in the product.

[0108] Table 1 Performance test results of different OCA optical adhesives

[0109]

[0110] From the above test results, it can be seen that by modifying the acrylic prepolymer and adding a certain amount of functional additives, the surface wettability and bonding performance of the low surface energy substrate can be significantly improved, while ensuring good lamination performance. If the acrylic prepolymer is not modified or the corresponding functional additives are not used, it is impossible to improve the bonding performance and lamination performance of the low surface energy substrate.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. OCA optical adhesive, characterized in that: The invention comprises the following components in parts by weight: 85-95 parts of modified silicone prepolymer, 5-15 parts of crosslinking agent, 0.01-0.1 parts of first photoinitiator and 0.1-2 parts of functional additive; The modified silicone prepolymer is mainly prepared from the following components by weight: 30-60 parts of vinyl-terminated siloxane, 40-70 parts of monomer, 0.01-1 parts of second photoinitiator and 0.002-0.2 parts of chain transfer agent; The functional additives include: (a) Tetrabutylammonium bromide; (b) other auxiliary agents, wherein the other auxiliary agents are selected from at least one of aluminum acetylacetonate and triphenylphosphine; The mass ratio of the tetrabutylammonium bromide to the other auxiliary agents is 3: (2-4); The mass ratio of the terminal vinyl siloxane in the modified silicone prepolymer to the functional additive is (50-200):1; The monomer comprises at least one of isooctyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, isobutyl acrylate and 2-phenoxyethyl acrylate; The crosslinking agent includes at least one of 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, cyclohexanedimethanol diacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, trimethylolpropane triacrylate, ditrimethylolpropane acrylate and dipentaerythritol hexaacrylate; The vinyl-terminated siloxane is methyl vinyl polysiloxane.

2. The OCA optical adhesive according to claim 1, characterized in that: The first photoinitiator and the second photoinitiator are each independently selected from at least one of photoinitiator TPO, photoinitiator 184 and photoinitiator 1173.

3. The OCA optical adhesive according to claim 1, characterized in that: The viscosity of the modified silicone prepolymer is 2500-4000 cps.

4. The method for preparing the OCA optical adhesive according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: mixing the components in proportion and then subjecting the components to ultraviolet curing for forming.

5. Touch screen, characterized in that, The invention comprises the OCA optical adhesive as described in any one of claims 1 to 3 or the OCA optical adhesive prepared by the preparation method as described in claim 4.

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