Low-dielectric OCA for touch screen and preparation method of low-dielectric OCA

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a low-dielectric OCA for a touch screen and a preparation method of the low-dielectric OCA. The low-dielectric OCA for the touch screen is prepared from the following raw materials in parts by weight: 50 to 80 parts of acrylate low-dielectric monomers, 10 to 40 parts of acrylate soft monomers, 5 to 20 parts of acrylate high-polarity monomers, 0.05 to 2 parts of a photoinitiator, 0.05 to 5 parts of a polyfunctional group cross-linking agent, 0.005 to 2 parts of a coupling aid and 0.01 to 0.5 part of a chain transfer agent. By selecting specific components and optimizing the preparation process, the dielectric constant and dielectric loss of the OCA are effectively reduced, meanwhile, excellent bonding strength and good weather resistance are kept, after the OCA is matched with a touch screen module to be attached, the OCA can pass consumer electronics standard environment testing (double-85 aging for 504 h) and high-altitude low-voltage testing (60 DEG C * 40 kPa * 16 h) for simulating air transportation, and the OCA has the good application prospect. The appearance and function problems such as bubbles and obvious yellowing are not generated, and the method can be widely applied to the field of assembly of various touch screens.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and in particular relates to a low-dielectric OCA for touch screens and a preparation method thereof. Background Art

[0002] Optical adhesives (OCA) are widely used in electronic devices such as smartphones, tablets, touchscreen monitors, and e-readers due to their excellent optical properties and good bonding performance. As the market develops, more and more traditional laptops are adding touch functionality. While standard full-bonding adhesives are generally sufficient for manual touch, the advent of styluses has led to higher requirements for touch sensitivity, necessitating the use of low-dielectric, full-bonding OCAs.

[0003] While traditional OCA materials can meet basic transparency and adhesion requirements, they often have limitations in dielectric properties. Their high dielectric constant and dielectric loss can easily lead to problems such as signal transmission delays and increased power consumption in touchscreens. This is particularly evident during high-frequency signal transmission and complex touch operations. Furthermore, the trend toward thinner, lighter, and higher-resolution touchscreens places even higher demands on OCA materials for low dielectric properties, high light transmittance, high bonding strength, and excellent weather resistance.

[0004] Although there have been some research and development attempts on low-dielectric OCA in the market, most products still face challenges such as complex preparation processes, high costs, and poor environmental adaptability, making it difficult to meet the needs of large-scale industrial production.

[0005] Therefore, developing a low-dielectric OCA for touch screens with simple preparation process, low cost and excellent performance has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] The purpose of the present invention is to provide a low-dielectric OCA for touch screens and a preparation method thereof. By selecting specific components and optimizing the preparation process, the dielectric constant of the OCA is effectively reduced while maintaining excellent bonding strength and good weather resistance.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A low-dielectric OCA for touch screens is prepared from raw materials, by weight, including 50-80 parts of an acrylate low-dielectric monomer, 10-40 parts of an acrylate soft monomer, 5-20 parts of an acrylate high-polarity monomer, 0.05-2 parts of a photoinitiator, 0.05-5 parts of a multifunctional cross-linking agent, 0.005-2 parts of a coupling aid, and 0.01-0.5 parts of a chain transfer agent.

[0009] Preferably, the acrylic low dielectric monomer includes one or more of lauryl acrylate, lauryl methacrylate, myristyl methacrylate, heptadecyl acrylate, and octadecyl acrylate; further preferably, lauryl acrylate, myristyl methacrylate, and octadecyl acrylate.

[0010] Preferably, the mass ratio of lauryl acrylate, tetradecyl methacrylate and octadecyl acrylate is (2-4):(2-3):1; more preferably, it is 9:8:3.

[0011] The use of lauryl acrylate, tetradecyl methacrylate, and octadecyl acrylate as low-dielectric monomers in the acrylic ester class not only improves the peel strength of the OCA but also reduces the dielectric constant. This is because these monomers work synergistically. On the one hand, the long alkyl chain structure they contain not only enhances the interaction between molecules but also increases the contact area between the adhesive and the adherend surface, thereby effectively improving the peel strength. On the other hand, these low-dielectric monomers have a low polarizability and can significantly reduce the dielectric constant of the cured adhesive, which is crucial for high-frequency electronic components such as touch screens. In addition, lauryl acrylate, tetradecyl methacrylate, and octadecyl acrylate all have good weather resistance and can resist damage to the adhesive's performance caused by environmental factors such as temperature and humidity, thereby extending its service life. Moreover, the low viscosity and dilution effect of lauryl acrylate help improve the processing performance of the adhesive, while the long-chain structures of tetradecyl methacrylate and octadecyl acrylate enhance the flexibility and stability of the adhesive, respectively. This not only helps alleviate stress concentration problems caused by changes in air pressure, but also improves the material's gas barrier properties and reduces the penetration of air or other gas molecules, thereby indirectly enhancing the stability and durability of OCA in high-altitude, low-pressure environments, ensuring that it will not deform or be damaged due to changes in external conditions, and meeting the high requirements for adhesive performance in applications such as touch screens.

[0012] Preferably, the acrylic soft monomer includes one or more of 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate and isobutyl acrylate; more preferably, it is 2-ethylhexyl acrylate, isooctyl acrylate and butyl acrylate.

[0013] Preferably, the mass ratio of 2-ethylhexyl acrylate, isooctyl acrylate and butyl acrylate is (2-4):(1-3):1; more preferably, it is 3:2:1.

[0014] Preferably, the acrylic acid ester high polarity monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N,N-dimethylacrylamide, and N-vinyl pyrrolidone; further preferably, it is hydroxyethyl acrylate, N-vinyl pyrrolidone and N,N-dimethylacrylamide.

[0015] Preferably, the mass ratio of hydroxyethyl acrylate, N-vinyl pyrrolidone and N,N-dimethylacrylamide is (1-3): (1-3): 1; more preferably, it is 2:2:1.

[0016] The use of hydroxyethyl acrylate, N-vinyl pyrrolidone, and N,N-dimethylacrylamide as highly polar acrylic monomers not only further enhances peel strength but also improves the weatherability of the OCA. This is likely due to the abundant hydroxyl groups in hydroxyethyl acrylate, which form strong hydrogen bonds and other polar interactions with the substrate surface, significantly enhancing adhesion. This results in a final product with higher peel strength and maintains good adhesion even under prolonged use or extreme conditions. N-vinyl pyrrolidone and N,N-dimethylacrylamide exhibit excellent film-forming properties and chemical resistance, significantly enhancing the material's UV resistance and chemical stability. These monomers, acting synergistically with the hydroxyl groups in hydroxyethyl acrylate, help improve the material's hydrophilicity and wettability, reducing moisture-induced degradation. This improves the material's overall weatherability, enabling it to maintain stable physical and electrical properties under high temperature, high humidity, or outdoor UV exposure conditions. However, these monomers are inherently highly polar, which may affect the dielectric properties of the OCA. By controlling the mass ratio of each highly polar monomer, the intermolecular polar interactions are regulated, thus preventing the addition of highly polar monomers from affecting the dielectric properties of the entire system. The hydroxyl group in hydroxyethyl acrylate can participate in the hydrogen bonding network to a certain extent, reducing the number of free dipole moments; while N-vinyl pyrrolidone and N,N-dimethylacrylamide disperse the polarity contribution through their structural characteristics, avoiding the impact of excessive local polarity on dielectric properties. By rationally compounding these monomers, the dielectric constant can be controlled at a low level while improving the peel strength and weather resistance of the OCA, making it suitable for touch screen applications with strict dielectric performance requirements.

[0017] Preferably, the photoinitiator includes one or more of photoinitiator TPO, photoinitiator 184, photoinitiator 819, photoinitiator 1173, photoinitiator 651, and photoinitiator MBF; further preferably, photoinitiator TPO, photoinitiator 819, and photoinitiator 651.

[0018] Preferably, the mass ratio of the photoinitiator TPO, photoinitiator 819, and photoinitiator 651 is (1-3): (1-3): 1; more preferably, it is 2:2:1.

[0019] Preferably, the multifunctional crosslinking agent is one or more of an acrylate monomer with a functional group ≥2 and a difunctional polyurethane acrylate oligomer; further preferably, it is an acrylate monomer with a functional group ≥2 and a difunctional polyurethane acrylate oligomer.

[0020] Preferably, the mass ratio of the acrylate monomer with a functional group ≥ 2 to the difunctional polyurethane acrylate oligomer is (5-7):1; more preferably, it is 6:1.

[0021] Preferably, the acrylate monomer with a functional group ≥2 includes one or more of triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, and 1,3-butanediol dimethacrylate; further preferably, triethylene glycol dimethacrylate and 1,6-hexanediol diacrylate.

[0022] Preferably, the mass ratio of triethylene glycol dimethacrylate to 1,6-hexanediol diacrylate is (1-2):1; more preferably, it is 3:2.

[0023] Preferably, the bifunctional polyurethane acrylate oligomer is an aliphatic polyurethane acrylate oligomer.

[0024] In some preferred embodiments, the bifunctional polyurethane acrylate oligomer can be selected from Any one of Xidon New Materials QDSRAYS UV021, Tangyi Chemical YC2528, Sartomer CN9893, and Guangdong Suyuan SU-8122.

[0025] The use of specific acrylate monomers with a functional group count of ≥2 and difunctional urethane acrylate oligomers as multifunctional crosslinkers not only further enhances the peel strength between the OCA and glass but also improves its stability. This is likely due to the synergistic effect between these crosslinkers. The high reactivity and multifunctionality of the acrylate monomers complement the carbamate and acrylate functional groups of the urethane acrylate oligomers, forming a more complex and stable crosslinked structure. This structure not only enhances the mechanical strength, peel strength, and weather resistance of the photocurable adhesive, but also optimizes the dielectric properties by finely controlling the flexibility and polarity of the molecular chain, ensuring the maintenance of a low dielectric constant and low dielectric loss.

[0026] Preferably, the coupling aid includes one or more of γ-aminopropyltriethoxysilane, γ-glycidyl ether propyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; further preferably, γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0027] Preferably, the mass ratio of the γ-aminopropyltriethoxysilane to the γ-methacryloxypropyltrimethoxysilane is (1-2):1; more preferably, it is 3:2.

[0028] The selection of specific acrylate-based high-polarity monomers and specific coupling agents allows the colloid to have the dual effects of polar adsorption and coupling after being bonded to the glass panel. This not only increases the bonding strength and improves the peel strength of the OCA, but also makes the bonding more stable after ring testing, and can be used smoothly under conditions such as high temperature, high humidity, and high altitude and low pressure. This may be because the strong polar functional groups in the high-polarity monomer form hydrogen bonds or chemical bonds with the polar groups on the surface of the glass panel, achieving polar adsorption and enhancing the tightness and firmness of the bond. At the same time, the coupling agent reacts with inorganic groups such as silanol on the surface of the glass panel through its inorganic affinity groups (such as siloxane groups) to form chemical bonds, while the organic affinity groups (such as amino, methacryloyloxy, etc.) interact with the organic components in the colloid to achieve coupling between the colloid and the glass panel, further enhancing the bonding strength. This combination not only utilizes the complementarity between the functional groups to form a tighter bonding interface, but also improves the uniformity and stability of the system through segment mutual compatibility. During the curing process, the highly polar monomer reacts with the coupling agent to form a cross-linked network, which accelerates the polymerization process and improves the mechanical properties and stability of the colloid.

[0029] Preferably, the chain transfer agent is a mercaptan molecular weight regulator, including one or more of n-dodecyl mercaptan, n-butyl mercaptan, 2-mercaptoethanol, 3-mercaptopropionic acid, isooctyl mercaptan, and tert-butyl mercaptan; further preferably, n-dodecyl mercaptan and n-butyl mercaptan.

[0030] Preferably, the mass ratio of n-dodecyl mercaptan to n-butyl mercaptan is (3-5):1; more preferably, it is 4:1.

[0031] In some preferred embodiments, 3-mercaptopropionic acid may be additionally added in an amount of 0.5% to 2% of the total mass of n-dodecyl mercaptan and n-butyl mercaptan.

[0032] Preferably, the acid value of all raw materials is less than 1 mgKOH / g and the water content is less than 500 ppm.

[0033] The method for preparing the low-dielectric OCA for the touch screen comprises the following steps:

[0034] S1: Synthesis of acrylate prepolymer: Place acrylate low dielectric monomer, acrylate soft monomer, acrylate high polar monomer, half the mass of photoinitiator, and half the mass of chain transfer agent into a reactor, stir for 3-8 minutes under nitrogen protection, and then prepolymerize under UV light. When the system viscosity reaches 4000-6000 cps, stop irradiation to obtain acrylate prepolymer;

[0035] S2: preparing glue: uniformly mixing the acrylate prepolymer prepared in S1, the remaining photoinitiator, the multifunctional acrylate crosslinking agent, the coupling auxiliary agent and the remaining chain transfer agent, filtering and degassing to obtain the glue.

[0036] S3: Preparation of low-dielectric OCA film for touch screen: The glue prepared in S2 is coated between two layers of PET release films using a double-roller machine, and then cured under UV light for 2-5 minutes to obtain the OCA film.

[0037] Preferably, in step S3, the thickness of the PET release film is 75 μm and 100 μm, and the thickness of the OCA film is 200-215 μm.

[0038] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0039] 1. The present invention provides a low-dielectric optical fiber contact (OCA) for touch screens. By selecting specific components and optimizing the preparation process, the dielectric constant and dielectric loss of the OCA are effectively reduced while maintaining excellent bonding strength and good weather resistance. After being bonded to a touch screen module, the OCA can pass standard environmental testing for consumer electronics products (double 85 aging for 504 hours) and high-altitude, low-pressure testing (60°C*40kPa*16 hours) simulating air transportation without causing appearance or functional issues such as bubbles and obvious yellowing. Therefore, the OCA can be widely used in various touch screen assembly fields.

[0040] 2. The present invention uses acrylic acid ester low dielectric monomers to participate in polymerization, so that the finished tape has a dielectric constant of less than 3.0. The screen bonded with this OCA has higher touch sensitivity. On the other hand, the combination of high polarity monomers and coupling agents makes the colloid have the dual effects of polar adsorption and coupling after being bonded to the glass panel, resulting in greater bonding strength and more stable bonding after ring testing.

[0041] 3. The present invention uses lauryl acrylate, tetradecyl methacrylate and octadecyl acrylate as acrylic acid ester low dielectric monomers, which can not only improve the peel strength of OCA but also reduce the dielectric constant.

[0042] 4. The present invention uses hydroxyethyl acrylate, N-vinyl pyrrolidone and N,N-dimethylacrylamide as high-polarity acrylic acid ester monomers, which can not only further improve the peel strength, but also improve the weather resistance of OCA.

[0043] 5. The present invention selects specific high-polarity acrylic monomers and specific coupling agents, so that after the colloid is bonded to the glass panel, it has the dual effects of polar adsorption and coupling, which not only increases the bonding strength and improves the peel strength of the OCA, but also makes the bonding more stable after ring testing, and can be used smoothly under conditions of high temperature, high humidity, high altitude and low pressure.

[0044] 6. The present invention selects specific acrylate monomers with functional groups ≥2 and difunctional polyurethane acrylate oligomers as multifunctional crosslinking agents, which can not only further improve the peel strength between OCA and glass, but also improve its stability. DETAILED DESCRIPTION

[0045] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0046] The raw materials used in the present invention are all commercially available, specifically:

[0047] The difunctional polyurethane acrylate oligomer is an aliphatic polyurethane acrylate oligomer purchased from Allnex.

[0048] Example 1

[0049] This embodiment provides a low-dielectric OCA for a touch screen. The raw materials for its preparation, calculated by weight, are 65 parts of an acrylate low-dielectric monomer, 25 parts of an acrylate soft monomer, 15 parts of an acrylate high-polarity monomer, 0.5 parts of a photoinitiator, 0.5 parts of a multifunctional cross-linking agent, 0.5 parts of a coupling aid, and 0.02 parts of a chain transfer agent.

[0050] The acrylic acid ester low dielectric monomer is lauryl acrylate, tetradecyl methacrylate and octadecyl acrylate, with a mass ratio of 9:8:3.

[0051] The acrylic soft monomers are 2-ethylhexyl acrylate, isooctyl acrylate and butyl acrylate in a mass ratio of 3:2:1.

[0052] The acrylic acid ester high polar monomer is hydroxyethyl acrylate, N-vinyl pyrrolidone and N,N-dimethylacrylamide, with a mass ratio of 2:2:1.

[0053] The photoinitiators are photoinitiator TPO, photoinitiator 819, and photoinitiator 651, with a mass ratio of 2:2:1.

[0054] The multifunctional crosslinking agent is an acrylate monomer with a functional group of ≥2 and a difunctional polyurethane acrylate oligomer, with a mass ratio of 6:1.

[0055] The acrylate monomer with a functional group of ≥2 is triethylene glycol dimethacrylate and 1,6-hexanediol diacrylate, with a mass ratio of 3:2.

[0056] The coupling auxiliary agent is γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane, with a mass ratio of 3:2.

[0057] The chain transfer agent is n-dodecyl mercaptan, n-butyl mercaptan and 3-mercaptopropionic acid; the mass ratio of n-dodecyl mercaptan to n-butyl mercaptan is 4:1; the addition amount of 3-mercaptopropionic acid is 1% of the total mass of n-dodecyl mercaptan and n-butyl mercaptan.

[0058] The acid value of all raw materials is less than 1mgKOH / g and the water content is less than 500ppm.

[0059] The method for preparing the low-dielectric OCA for the touch screen comprises the following steps:

[0060] S1: Synthesis of acrylate prepolymer: Place acrylate low dielectric monomer, acrylate soft monomer, acrylate high polar monomer, half the mass of photoinitiator, and half the mass of chain transfer agent into a reactor. Stir for 5 minutes under nitrogen protection, and then prepolymerize under UV light. When the system viscosity reaches 5000 cps, stop irradiation to obtain acrylate prepolymer.

[0061] S2: Preparation of glue: The acrylate prepolymer prepared in S1, the remaining photoinitiator, the multifunctional acrylate crosslinker, the coupling aid, and the remaining chain transfer agent are uniformly stirred, filtered, and degassed to obtain a low-dielectric OCA for touch screens.

[0062] Example 2

[0063] The difference between this embodiment and embodiment 1 is that the low-dielectric OCA for the touch screen is prepared from the following raw materials, in parts by weight: 60 parts of an acrylate low-dielectric monomer, 15 parts of an acrylate soft monomer, 20 parts of an acrylate high-polarity monomer, 0.4 parts of a photoinitiator, 0.5 parts of a multifunctional cross-linking agent, 0.5 parts of a coupling aid, and 0.02 parts of a chain transfer agent.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that the low-dielectric OCA for the touch screen is prepared from raw materials, by weight, comprising 60 parts of an acrylate low-dielectric monomer, 15 parts of an acrylate soft monomer, 25 parts of an acrylate high-polarity monomer, 0.4 parts of a photoinitiator, 0.5 parts of a multifunctional cross-linking agent, 0.5 parts of a coupling aid, and 0.02 parts of a chain transfer agent.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that the acrylic acid ester low dielectric monomer is lauryl acrylate and tetradecyl methacrylate, and the mass ratio is 1:1.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that the acrylic acid ester high polarity monomer is hydroxyethyl acrylate and N-vinyl pyrrolidone, and the mass ratio is 1:1.

[0070] Comparative Example 4

[0071] The difference between this comparative example and Example 1 is that the multifunctional cross-linking agent is an acrylate monomer with a functional group ≥2.

[0072] Comparative Example 5

[0073] The difference between this comparative example and Example 1 is that the coupling auxiliary agent is γ-aminopropyltriethoxysilane.

[0074] Comparative Example 6

[0075] The difference between this comparative example and Example 1 is that the low-dielectric OCA for the touch screen is prepared from raw materials, by weight, comprising 65 parts of an acrylate low-dielectric monomer, 25 parts of an acrylate soft monomer, 15 parts of an acrylate high-polarity monomer, 0.5 parts of a photoinitiator, 0.5 parts of a multifunctional cross-linking agent, and 0.02 parts of a chain transfer agent.

[0076] Performance Testing

[0077] 180° peel force testing was conducted according to GB / T 2792-2014, and the 180° peel force (20 minutes) from a steel plate was recorded in N / inch. The dielectric constant of the OCA at a frequency of 100 kHz was measured using a dielectric constant tester. The module and glass cover were matched using a tablet computer, and then bonded to the OCA using a laminating machine to form a G+LCM structure. The samples were then deaerated (at 40°C, 3kg pressure, and 20 minutes) and allowed to stand for 24 hours to confirm the absence of bubbles. After 504 hours of testing, the bonded samples were removed and observed for any appearance abnormalities, such as bubbling. Furthermore, the samples were tested at 60°C and 40 kPa, simulating a high-altitude, low-pressure environment. After 16 hours of testing, the bonded samples were removed and observed for any appearance abnormalities, such as bubbling. The results are shown in Table 1.

[0078] Table 1 Measurement results

[0079] Peel force Dielectric constant Environmental test results High altitude low pressure test results Example 1 16.78 2.93 No bubbles No bubbles Example 2 15.94 2.98 No bubbles No bubbles Comparative Example 1 15.20 3.14 There are bubbles There are bubbles Comparative Example 2 14.37 3.27 There are bubbles There are bubbles Comparative Example 3 16.80 3.69 There are bubbles There are bubbles Comparative Example 4 14.63 3.50 There are bubbles There are bubbles Comparative Example 5 16.15 3.06 There are bubbles There are bubbles Comparative Example 6 14.11 3.02 There are bubbles There are bubbles

[0080] According to statistics, the low-dielectric OCA for touch screens prepared in Examples 1 and 2 of the present invention had a strong peel force, indicating high bonding strength with the glass substrate. The dielectric constant was less than 3, and they passed the high-temperature and high-humidity ring test and the high-altitude low-pressure test. Comparative Example 1, in which an excessive amount of high-polarity acrylate monomer was added, Comparative Example 2 did not add octadecyl acrylate, Comparative Example 3 did not add N,N-dimethylacrylamide, Comparative Example 4 did not add a difunctional polyurethane acrylate oligomer, Comparative Example 5 did not add γ-methacryloxypropyltrimethoxysilane, and Comparative Example 6 did not add a coupling agent, exhibited low peel force and a high dielectric constant, failing the ring test and the high-altitude low-pressure test. Therefore, the low-dielectric OCA for touch screens prepared using the raw materials and methods described in this application not only effectively reduces the dielectric constant of the OCA, but also maintains excellent bonding strength and good weather resistance. After being bonded to the touch screen module, it can pass the standard environmental test for consumer electronics products (double 85 aging for 504 hours) and the high-altitude and low-pressure test (60°C*40kPa*16h) simulating air transportation without producing appearance and functional problems such as bubbles and obvious yellowing. It can be widely used in various touch screen assembly fields.

[0081] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A low-dielectric OCA for a touch screen, characterized in that: The raw materials for its preparation include, by weight, 50-80 parts of acrylate low dielectric monomer, 10-40 parts of acrylate soft monomer, 5-20 parts of acrylate high polarity monomer, 0.05-2 parts of photoinitiator, 0.05-5 parts of multifunctional crosslinking agent, 0.005-2 parts of coupling auxiliary agent, and 0.01-0.5 parts of chain transfer agent; The acrylic acid ester low dielectric monomer includes one or more of lauryl acrylate, lauryl methacrylate, tetradecyl methacrylate, heptadecyl acrylate, and octadecyl acrylate; The acrylic acid ester high polarity monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N,N-dimethylacrylamide, and N-vinyl pyrrolidone.

2. The low-dielectric OCA for touch screen according to claim 1, wherein: The acrylic acid ester low dielectric monomers are lauryl acrylate, tetradecyl methacrylate and octadecyl acrylate.

3. The low-dielectric OCA for touch screen according to claim 2, wherein: The mass ratio of lauryl acrylate, tetradecyl methacrylate and octadecyl acrylate is (2-4): (2-3):

1.

4. The low-dielectric OCA for touch screen according to claim 1, wherein: The acrylic acid ester high polar monomers are hydroxyethyl acrylate, N-vinyl pyrrolidone and N,N-dimethylacrylamide.

5. The low-dielectric OCA for touch screen according to claim 4, characterized in that: The mass ratio of the hydroxyethyl acrylate, N-vinyl pyrrolidone and N,N-dimethylacrylamide is (1-3): (1-3):

1.

6. The low-dielectric OCA for touch screen according to claim 1, wherein: The acrylic soft monomer includes one or more of 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate and isobutyl acrylate.

7. The low-dielectric OCA for a touch screen according to claim 1, wherein: The photoinitiator includes one or more of photoinitiator TPO, photoinitiator 184, photoinitiator 819, photoinitiator 1173, photoinitiator 651, and photoinitiator MBF.

8. The low-dielectric OCA for a touch screen according to claim 1, wherein: The multifunctional crosslinking agent is one or more of an acrylate monomer with a functional group of ≥2 and a difunctional polyurethane acrylate oligomer.

9. The low-dielectric OCA for touch screen according to claim 8, characterized in that: The bifunctional polyurethane acrylate oligomer is an aliphatic polyurethane acrylate oligomer.

10. A method for preparing a low-dielectric OCA for a touch screen according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Synthesis of acrylate prepolymer: Place acrylate low dielectric monomer, acrylate soft monomer, acrylate high polar monomer, half the mass of photoinitiator, and half the mass of chain transfer agent into a reactor, stir for 3-8 minutes under nitrogen protection, and then prepolymerize under UV light. When the system viscosity reaches 4000-6000 cps, stop irradiation to obtain acrylate prepolymer; S2: preparing glue: mixing the acrylate prepolymer prepared in S1, the remaining photoinitiator, the multifunctional acrylate crosslinking agent, the coupling aid and the remaining chain transfer agent, filtering and degassing to obtain glue; S3: Preparation of low-dielectric OCA film for touch screen: The glue prepared in S2 is coated between two layers of PET release films using a double-roller machine, and then cured under UV light for 2-5 minutes to obtain the OCA film.