CN112760044B - High-dielectric optical cement - Google Patents

Abstract

The invention discloses a high dielectric optical adhesive and a preparation method thereof, wherein the raw materials of the optical adhesive comprise an acrylate prepolymer, an acrylate diluent monomer, a photoinitiator, a chain transfer agent, an ultraviolet light stabilizer and an antioxidant, wherein the mole number of hydroxyl contained in each 100g of the optical adhesive is between 0.53 and 0.6, the storage modulus of the optical adhesive is between 3.0 and 30 ten thousand Pa under the conditions of 25 ℃ and 1Hz, and the weight average molecular weight of the optical adhesive is between 80 and 120 ten thousand g/mol. The dielectric constant of the optical adhesive under the frequency of 100KHz can reach at least 10.0, the optical adhesive has excellent ink section difference filling rate, the ink section difference filling rate is at least 20%, bubbles do not exist under the conditions of room temperature standing and high temperature, high humidity and aging after the optical adhesive is attached to a cover plate and a polaroid with the ink section difference, and the optical adhesive can be applied to bonding of a display module with an Oncell/Incell structure and improve the touch sensitivity of the Oncell/Incell structure.

Description

High-dielectric optical cement

Technical Field

The invention relates to the technical field of pressure-sensitive adhesives, in particular to a high-dielectric optical adhesive and a preparation method thereof.

Background

In recent years, with the rapid development of display technologies of electronic products such as mobile phones, display module structures suitable for OCA full lamination gradually transition from traditional G + G, G + F to more diversified display module structures such as (Incell/Incell), and the usage of the current Incell/Incell structure is on the trend of increasing year by year. The Oncell display module structure and the Incell display module structure are different from the traditional G + G and G + F display module structures in the positions of the touch units. For G + G and G + F + F display modules, the cover plate part is divided into touch units and has a touch function. For the Incell/Oncell structure display module, the cover plate part is not integrated with a touch unit and does not have a touch function. For the Oncell, the position of the touch unit is above the filter layer, and for the Incell, the touch unit is below the filter layer. The distance between the touch unit and the cover plate is obviously larger than that of the traditional G + G/G + F + F display module structure. Therefore, under the display module structure applying the Oncell/Incell, the touch sensitivity of the mobile phone is obviously smaller than that of the traditional G + G/G + F + F structure.

The optical cement is an important part for bonding the touch module and the display module. Based on this background, it is necessary to increase the dielectric constant of the OCA to compensate for the decrease in touch sensitivity due to the difference in display structure. The dielectric constant of the conventional acrylate OCA is about 4.0 at 100Hz frequency, and the requirement of an Oncell/Incell structure on touch sensitivity cannot be met.

And the increase in dielectric constant can be achieved by introducing a hydroxyl group-containing monomer. The hydroxyl group-containing monomer generally has a high molecular polarity, a high dipole moment, and the like, and thus can provide a higher dielectric constant of the OCA. After the hydroxyl-containing monomer is introduced, hydroxyl and hydroxyl in the acrylate polymer can form hydrogen bond action, and the cohesive property and the adhesive force property of the OCA are improved. On the other hand, if the amount of the hydroxyl group-containing monomer is too large, the concentration of hydrogen bonds formed between hydroxyl groups and hydroxyl groups becomes too high, and the polarity inside the OCA becomes too high, resulting in poor fluidity and adhesion, and in particular, in the high-temperature, high-humidity aging process, the reliability risk is generated, and the filling rate of the ink level difference is reduced. Therefore, the proportion of the hydroxyl-containing monomer added needs to be reasonably controlled, the mole number of the hydroxyl in the whole OCA optical cement is controlled, if the mole number proportion is too low, the dielectric constant of the OCA is insufficient, and if the proportion is too high, the polarity of the OCA is too high, the fluidity is insufficient, and the filling efficiency of the ink step difference is reduced.

At present, the mature products of the high dielectric OCA in the market are few, and the main reason is that the balance between the high dielectric constant and the excellent filling rate of the ink section difference is difficult to achieve from the aspect of formula design. Even though many OCA products have high dielectric constants, the filling rate of the ink segment difference is often poor (less than 10 percent), and the basic application requirements of the OCA cannot be met.

In order to solve the above-mentioned technical problems, patent CN 106795405B (optical clear adhesive and optical laminate) proposes a high dielectric OCA having both adhesive strength and cohesive strength, but its dielectric constant can only be achieved to be not less than 8.0, and no specific range is given for the performance level of the OCA that fills up the ink level difference, and no applicability of the OCA and the ink level difference and the polarizer under the conditions of high temperature, high humidity and aging is proposed.

How to solve the above technical problems is a matter that those skilled in the art are dedicated to solve.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the high-dielectric pressure-sensitive adhesive with high dielectric constant and high ink section difference filling rate.

In order to achieve the purpose, the invention adopts the technical scheme that: the raw materials of the optical adhesive comprise an acrylate prepolymer, an acrylate diluent monomer, a photoinitiator, a chain transfer agent, an ultraviolet light stabilizer and an antioxidant, wherein the mole number of hydroxyl contained in each 100g of the optical adhesive is between 0.53 and 0.6, the storage modulus of the optical adhesive at 25 ℃ and 1Hz is between 3.0 and 30 ten thousand Pa, and the weight average molecular weight of the optical adhesive is between 80 and 120 ten thousand g/mol.

As a specific embodiment, the raw materials of the optical adhesive comprise, by mass, 50-80 parts of an acrylate prepolymer, 20-50 parts of an acrylate diluent monomer, 0.5-2 parts of a photoinitiator, and 0.2-0.8 part of a chain transfer agent.

As a specific embodiment, the acrylate prepolymer is prepared by bulk polymerization of acrylate monomers.

As a specific embodiment, the acrylate diluent monomer includes a hydroxyl-containing alkyl acrylate monomer and a non-hydroxyl-containing alkyl acrylate monomer.

As a specific embodiment, the hydroxyl group-containing alkyl acrylate monomer is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, glycerol 1-methacrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, 1,4 cyclohexanedimethanol monoacrylate, caprolactone acrylate; the acrylic acid alkyl ester monomer without hydroxyl is selected from one or more of isooctyl acrylate, butyl acrylate, 2 (2-ethoxy) ethyl acrylate, dodecyl acrylate and isodecyl acrylate.

As a specific embodiment, the photoinitiator is selected from one or more of 2-hydroxy-2 methyl-phenyl acetone-1, 1-hydroxy-cyclohexyl benzophenone, benzoyl formate, 2,4, 6-trimethylbenzoyl-diphenyl phosphine oxide, 4-methylbenzophenone.

As a specific embodiment, the chain transfer agent is selected from one or more of n-dodecyl mercaptan, tert-dodecyl mercaptan, isooctyl thioglycolate, isooctyl 3-mercaptopropionate, pentaerythritol tetrakis (3-mercaptobutyrate).

In a specific embodiment, the ultraviolet light stabilizer is benzotriazole.

As a specific embodiment, the antioxidant is 4, 6-bis (octylthiomethyl) o-cresol.

The invention also aims to provide a preparation method of the high-dielectric optical cement, which comprises the following steps:

sequentially adding the acrylate prepolymer, the acrylate diluent monomer, the photoinitiator, the chain transfer agent, the ultraviolet light stabilizer and the antioxidant into a reaction kettle, stirring and mixing for 4-5 hours at the temperature of 30-50 ℃, then defoaming for 1 hour in vacuum, standing, defoaming and storing to obtain the required optical adhesive.

As a specific implementation mode, the optical adhesive can be cured by means of ultraviolet light irradiation, and the total energy of the ultraviolet light is 800-1500mj/cm²The ultraviolet light illumination intensity is 10-80mw/cm²The wavelength range of the ultraviolet light is 200-420 nm.

As a specific implementation mode, the preparation method of the high dielectric optical cement is prepared by the following steps:

weighing the acrylate prepolymer, the acrylate diluent monomer, the photoinitiator, the chain transfer agent, the ultraviolet light stabilizer and the antioxidant in parts by mass, sequentially adding the materials into a reaction kettle, setting the raw materials at 40 ℃, stirring for 4 hours, defoaming in vacuum for 1 hour, standing, defoaming and storing in a dark place.

Uniformly coating the defoamed OCA optical cement in the middle of two layers of polyethylene terephthalate films (PET release films) coated with organic silicon release materials, and passing throughThe OCA optical cement is cured by means of ultraviolet irradiation, and the thickness of the obtained optical cement is controlled to be 100 um. The total energy of the ultraviolet light is 1000mj/cm²The ultraviolet light illumination intensity is 50mw/cm²The wavelength range of the ultraviolet light is 365 nm.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the high-dielectric optical adhesive adopts the acrylate prepolymer, the acrylate diluent monomer, the photoinitiator, the chain transfer agent, the ultraviolet light stabilizer and the antioxidant, and the dielectric constant of the optical adhesive is high and can reach more than 10.0 under the frequency condition of 100Hz by adjusting the using amount of the chain transfer agent and the mole number of hydroxyl in the optical adhesive; meanwhile, the dielectric constant, the storage modulus and the molecular weight of the optical adhesive are dynamically balanced without sacrificing the overall fluidity of the optical adhesive, and the optical adhesive has excellent ink level difference filling performance, wherein the fact that the optical adhesive has the ink level difference filling performance means that the OCA does not generate bubbles under the conditions of room temperature standing and high temperature and high humidity aging after being attached to a cover plate with the ink level difference and a polaroid. The filling property of the ink section difference can be more than 20%, namely the filling property means that the filling property is calculated by optical adhesive 100um, after a cover plate with the ink section difference more than 20um and a polaroid are attached, an attaching sheet is placed under the conditions of normal temperature, high temperature and high humidity, no bubbles are generated between the optical adhesive and the cover plate and between the optical adhesive and each layer of the polaroid, and the optical adhesive can be applied to a display device with an Incell/Oncell display structure.

Detailed Description

The technical solution of the present invention is further illustrated below with reference to specific examples.

In the following examples, the hydroxyl-containing alkyl acrylate is selected from hydroxybutyl acrylate (4-HBA) and hydroxyethyl acrylate (HEA); the alkyl acrylate without hydroxyl group is selected from Butyl Acrylate (BA), isooctyl acrylate (2-EHA) and 2 (2-ethoxyethoxy) ethyl acrylate (EOEOEA); the photoinitiator is 1-hydroxycyclohexyl phenyl ketone (184); the chain transfer agent selects n-dodecyl ester (NDM), isooctyl thioglycolate (IOTG) and tert-dodecyl isooctyl (TDM); benzotriazole is selected as the ultraviolet stabilizer; the antioxidant is 4, 6-di (octylthiomethyl) o-cresol.

Example 1

The embodiment provides a preparation method of high dielectric OCA, which comprises the following specific steps of weighing raw materials in parts by mass: the method comprises the following steps of sequentially putting raw materials of an acrylate prepolymer, an acrylate diluent monomer, a photoinitiator, an ultraviolet light stabilizer and an antioxidant into a reaction kettle, continuously stirring, controlling the stirring temperature to be 40 ℃ by using a mold temperature controller, and stirring for 4 hours. And (4) after stirring, carrying out vacuum defoaming with the defoaming vacuum degree of-930 to-990 mbar and the defoaming time of 1 hour. Obtaining the OCA optical cement.

Specifically, the acrylate prepolymer in this example can be prepared by the following method:

in a vertical reaction kettle, 60 parts of hydroxybutyl acrylate and 5 parts of isooctyl acrylate are mixed to form a mixture, 0.4 part of thermal initiator AIBN (azobisisobutyronitrile) is added, nitrogen atmosphere is introduced for purging for 30min, oxygen in the kettle is removed, and the mixture is polymerized to 20 percent conversion rate under the condition of heating to 85 +/-2 ℃ to obtain a pre-polymerization solution with the viscosity of 1 Pa.s. The prepolymer was transferred to a water bath at 40. + -. 2 ℃ and continuously stirred under nitrogen atmosphere for further polymerization for 8 hours. If the system reaction heat is too large or the viscosity suddenly rises, circulating cold water is introduced to reduce the temperature in time, and finally the conversion rate of the oligomer is controlled to be 60 +/-1% and the viscosity is controlled to be 5 Pa.s. And finally, adding 30 parts of hydroxybutyl acrylate and 5 parts of isooctyl acrylate for dilution to obtain a final prepolymer, wherein the partial content of the polymer in the finally obtained prepolymer is 40%, and the viscosity is 3 Pa.s. The acrylate prepolymer was designated a 1.

Adding 60 parts by mass of acrylate prepolymer A1 into a stirring kettle, and then sequentially adding the following raw materials: acrylate diluent monomer, chain transfer agent, antioxidant, ultraviolet light stabilizer and heat stabilizer.

Adding acrylate diluent monomer which comprises hydroxyl-containing alkyl acrylate and non-hydroxyl-containing alkyl acrylate monomer, wherein the hydroxyl-containing alkyl acrylate monomer is selected to be 28 parts by mass of butyl acrylate, and the non-hydroxyl-containing alkyl acrylate monomer is selected to be 9 parts by mass of butyl acrylate; 1.5 parts of 1-hydroxy-cyclohexyl benzophenone by mass; the chain transfer agent is selected to be n-dodecyl mercaptan with the mass part of 0.5, and the ultraviolet light stabilizer is selected to be benzotriazole with the mass part of 0.5; the antioxidant is selected to be 0.5 part of 4, 6-di (octylthiomethyl) o-cresol.

And (3) after the raw materials are mixed in the stirring kettle, controlling the temperature in the stirring kettle at 40 ℃, stirring for 4 hours, and after the stirring is finished, carrying out vacuum defoaming for 1 hour to obtain the OCA optical cement, and storing the OCA optical cement in a dark place for later use.

Coating the mixed OCA optical glue solution between two PET release films, and performing ultraviolet curing on the OCA optical glue solution between the two PET release films by using a metal halogen lamp at 1000mj/cm²The ultraviolet light energy is used for curing, and the illumination intensity of the ultraviolet light is 50mw/cm²And the wavelength of ultraviolet light illumination is 365nm, the coating thickness of the OCA is controlled to be 100um, and the OCA optical cement product is obtained after curing is finished.

The compounding ratios of other specific examples and comparative examples are shown in Table 1.

The number of moles of hydroxyl groups in each of examples and comparative examples was calculated.

The number of moles of hydroxyl groups in 100g of OCA was calculated according to the following formula:

the mass of W1, W2, … Wi in 100g of OCA hydroxyl-containing monomer 1,2, … … i

I molecular weight of M1, M2, … Mi hydroxyl-containing monomers 1,2

The number of hydroxyl groups contained in the N1, N2, … Ni hydroxyl group-containing monomers 1,2, … … … i

The performance of the OCA optical cement product obtained in table 1 was tested, and the test results are shown in table 2. The test method is as follows:

firstly, the molecular weight of the obtained OCA optical cement product in the table 1 is measured.

The average molecular weight and molecular weight distribution of the acrylic polymer contained in the prepared OCA product were measured by GPC measurement, and the measurement apparatus: HLC-8120GPC (manufactured by Tosoh Corporation) GPC column constitution: the following 5 columns (all manufactured by Tosoh Corp.)

(1) TSK-GEL HXL-H (guard column)

(2)TSK-GEL G 7000H X L.

(3)TSK-GEL GMHXL

(4)TSK-GEL GMHXL

(5)TSK-GEL G 2500H X L.

Sample concentration: diluting with tetrahydrofuran to 1.0mg/cm³And a mobile phase solvent: tetrahydrofuran, flow rate: 1.0cm³Min, column temperature: at 40 ℃.

Secondly, the dielectric constant of the OCA product obtained in table 1 was measured:

the test method comprises the following steps: the OCA was laminated to 300um and tested for dielectric constant at a frequency of 100KHz at 25 ℃ using a dielectric constant tester, model No. (Keysight Co., Ltd.: E4980 AL).

Thirdly, the elastic modulus of the OCA product obtained in the table 1 is measured:

the test method comprises laminating OCA to 1000um, and measuring storage modulus with rheometer (TA model DHR-2). The parallel plate fixture is adopted, the test mode is set to be the oscillation mode, and the strain is controlled to be 0.1%. The change in the elastic modulus of the OCA with temperature was measured. The temperature scanning range is-40-150 ℃, the heating rate is 3 ℃/min, and the frequency is 1 Hz.

Fourthly, the glass transition temperature of the OCA product obtained in the table 1 is measured:

the test method comprises the following steps: the glass transition temperature of OCA was detected by Differential Scanning Calorimeter (DSC) measurement method. A measuring device: pyris DSC-8000 (manufactured by Perkin Elmer). The testing temperature range is-60-100 ℃, and the heating rate is 5 ℃/min.

Fifthly, carrying out adhesion force test on the OCA obtained in the table 1:

cutting the OCA into sample strips with the thickness of 25mm × 15cm, tearing off the light release film, attaching the sample strips to a glass substrate, compounding a layer of 25umPET substrate on the surface, rolling 3 times at the speed of 300mm/min by using a 2kg roller, placing the sample strips for 30min under the condition of constant temperature and humidity, and testing the adhesion of the OCA to the glass plate at the speed of 300mm/min by using a tensile machine.

Sixthly, evaluating the ink level difference filling performance of the OCA product obtained in the table 1:

the detailed steps are as follows:

1. removing the light release film from the cured OCA of 100um, attaching the OCA to CG with 15um ink section difference, and completing attaching by using an automatic roller press, wherein the attaching pressure is set to be 2kg, and the attaching rolling speed is 300 mm/min;

2. after the lamination with CG is finished, removing the heavy release film from the laminated OCA, laminating the OCA on a polarizer substrate with a display module in a vacuum laminating mode, and finishing the lamination by using an automatic hard laminating machine, wherein the laminating pressure is set to be 2.5kg, the vacuum degree is set to be 500Pa, and the laminating time is set to be 5 s;

3. placing the well-jointed sample in a vacuum defoaming furnace for pressure defoaming, wherein the defoaming conditions are as follows: 50 ℃, pressure: 0.5Mpa, time: 30 min;

4. standing at normal temperature for 24hrs, and observing whether bubbles exist between the OCA and the cover plate layer and between the OCA and the polarizer layer;

5. and if no bubbles are generated after standing at normal temperature, putting the pasted sample into an aging box at the temperature of 85 ℃/85RH percent, carrying out aging test for 3 days, taking out the sample, and observing whether bubbles exist between the OCA and the cover plate layer and between the OCA and the polarizer layer.

TABLE 1

Continuation of Table 1

TABLE 2

Continuation of Table 2

And (4) analyzing results:

1) influence of hydroxyl mole number in OCA optical cement on optical cement performance

As can be seen from Table 2, in examples 1 to 15, the molar ratio of the hydroxyl groups to the whole polymer was controlled to 0.53 to 0.6 for 100g of OCA, thereby achieving a balance between the dielectric constant and the filling property of the ink level difference.

From table 2, we can see that the control of the mole number of hydroxyl groups is crucial to the balance between the dielectric constant of the OCA optical cement and the filling property of the ink step difference. When the molar number of hydroxyl groups of the OCA is less than 0.5 (comparative example 5, comparative example 7, and comparative example 10), the polarity of the entire OCA is significantly insufficient, resulting in insufficient dielectric constant of the OCA (comparative example 5 is 7.8, comparative example 7 is 8.0, and comparative example 10 is 6.0), which in turn results in poor touch effect of the OCA in the Oncell/Incell display module.

On the other hand, the mole number of the hydroxyl groups of the OCA cannot be too high, when the mole number of the hydroxyl groups of the OCA is higher than 0.6 (such as comparative example 6, comparative example 8 and comparative example 9), although the dielectric constant of the OCA is higher (such as comparative example 6, the dielectric constant reaches 12 and the dielectric constant reaches 11.1), the OCA has too high internal polarity and is hindered in fluidity under the condition, the OCA has obviously improved weight average molecular weight and storage modulus due to the hydrogen bonding formed between the hydroxyl groups and the hydroxyl groups, the filling performance of the ink step difference of the OCA is obviously limited, the step difference cannot be effectively filled after the OCA is attached to the cover plate, and bubbles are generated under the conditions of normal temperature, high humidity and aging.

2) Effect on OCA gum Performance regarding the amount of chain transfer agent used

From table 2, we can see that the use and amount of chain transfer agent is critical to the ink step filling of OCA optical cement.

In examples 1 to 15, the balance between the dielectric constant and the filling property of the ink level difference is achieved by using the chain transfer agent and reasonably controlling the adding ratio of the chain transfer agent and the initiator under the premise of reasonably controlling the molar ratio of the hydroxyl groups to the whole polymer, wherein the using amount of the chain transfer agent is 0.2 to 0.8 percent.

When a chain transfer agent is added to the OCA, the weight average molecular weight and storage modulus of the entire OCA are reduced, the flowability of the OCA is improved, and the OCA may be filled with an ink level difference at an initial stage. When the amount of the chain transfer agent used is less than 0.2% (e.g., comparative example 1, comparative example 9), the OCA has an excessively high weight average molecular weight and an excessively high storage modulus (the weight average molecular weight is 1.6E6 g/mol, and the storage modulus is 7.0E 5Pa, without adding the chain transfer agent in comparative example 1), the OCA has poor fluidity, and the filling of the ink level difference cannot be completed.

On the other hand, the amount of chain transfer agent used may not be too high, and when the amount of chain transfer agent of OCA is more than 0.8% (as comparative example 2), the weight average molecular weight of OCA is too low and the storage modulus is too low (comparative example 2, the amount of chain transfer agent added is 1%, the medium weight average molecular weight is 5.0E5 g/mol, and the storage modulus is 1.2E4 Pa), although the initial fluidity of OCA is satisfactory and the filling of ink level differences can be completed at room temperature, the cohesive strength of OCA itself is poor, and when aging conditions of high temperature and high humidity are performed, the strength is insufficient due to too low amount of OCA molecular weight, the influence of environmental aging cannot be resisted, which is expressed as a decrease in adhesion and cohesive strength, and the occurrence of bubble defects after aging under high temperature and high humidity.

3) Effect of photoinitiator dosage on OCA adhesive Properties

From table 2, it can be seen that the amount of initiator is critical to the ink step filling of OCA optical cement. The dosage of the photoinitiator is controlled to be 0.5-2%, and the dosage of the initiator is controlled on the premise of reasonably controlling the dosage of chain transfer and the molar ratio of hydroxyl groups in the examples 1-15, so that the balance between the dielectric constant and the filling property of the ink step difference is realized. When the content of the initiator in the OCA is less than 0.5%, the weight average molecular weight of the OCA is too high and the storage modulus is too high (the amount of the initiator added in comparative example 3 is 0.4%, the storage modulus is 3.5E 5Pa, and the weight average molecular weight is 1.5E6), the basic fluidity of the OCA is not good, and even if a chain transfer agent is added, the fluidity of the OCA is difficult to improve, and the filling of the ink level difference cannot be completed.

On the other hand, the amount of the initiator may not be too high, and when the amount of the initiator is more than 2%, the weight average molecular weight of the OCA is too low and the storage modulus is too low (as in comparative example 4, the amount of the initiator is 2.2%, the storage modulus is 2.8E4 Pa, and the weight average molecular weight is 7.4E5 g/mol), although the initial fluidity of the OCA satisfies the requirement and the filling of the ink level difference can be completed at room temperature, the OCA itself has poor cohesive strength, and when the aging condition of high temperature and high humidity is performed, the OCA has too low molecular weight and insufficient strength, cannot resist the influence of environmental aging, and shows insufficient adhesion and adhesive strength, and the bubble defect appears after the aging condition of high temperature and high humidity.

In summary, the high dielectric OCA of the present invention improves the dielectric constant of the OCA by controlling the mole number of hydroxyl groups in the optical adhesive, and by reasonably controlling the ratio of the photoinitiator to the chain transfer agent, the improvement of the ink step gap filling property of the OCA can be achieved on the premise of having a high dielectric constant, so that 100um OCA is realized, after the 20um step gap cover plate and the polarizer are filled, no bubble appears after the OCA is placed under the aging conditions of normal temperature and high humidity, and the adhesion and application of the display module under the Incell/Oncell structure are satisfied.

The above embodiments are only for illustrating the technical idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention, and not to limit the protection scope of the present invention by this means. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (9)

1. The high-dielectric optical adhesive is characterized in that raw materials of the optical adhesive comprise an acrylate prepolymer, an acrylate diluent monomer, a photoinitiator, a chain transfer agent, an ultraviolet light stabilizer and an antioxidant, wherein the mole number of hydroxyl contained in each 100g of the optical adhesive is 0.53-0.6, the storage modulus of the optical adhesive at 25 ℃ and 1Hz is 3.0-30 ten thousand Pa, the weight average molecular weight of the optical adhesive is 80-120 ten thousand g/mol, and the raw materials of the optical adhesive comprise, by mass, 50-80 parts of the acrylate prepolymer, 20-50 parts of the acrylate diluent monomer, 0.5-2 parts of the photoinitiator and 0.2-0.8 part of the chain transfer agent.

2. The high-dielectric optical cement as claimed in claim 1, wherein the acrylate prepolymer is prepared by bulk polymerization of acrylate monomers.

3. The high dielectric optical glue of claim 1, wherein the acrylate diluent monomer includes a hydroxyl-containing alkyl acrylate monomer and a non-hydroxyl-containing alkyl acrylate monomer.

4. The high dielectric optical adhesive of claim 3, wherein the hydroxyl-containing alkyl acrylate monomer is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, glycerol 1-methacrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, 1,4 cyclohexanedimethanol monoacrylate; the acrylic acid alkyl ester monomer without hydroxyl is selected from one or more of isooctyl acrylate, butyl acrylate, 2 (2-ethoxy) ethyl acrylate, dodecyl acrylate and isodecyl acrylate.

5. The high dielectric optical glue of claim 1, wherein the photoinitiator is selected from one or more of 2-hydroxy-2 methyl-phenyl acetone-1, 1-hydroxy-cyclohexyl benzophenone, benzoyl formate, 2,4, 6-trimethylbenzoyl-diphenyl phosphine oxide, and 4-methyl benzophenone.

6. The optical glue of claim 1, wherein the chain transfer agent is selected from one or more of n-dodecyl mercaptan, t-dodecyl mercaptan, isooctyl thioglycolate, isooctyl 3-mercaptopropionate, pentaerythritol tetrakis (3-mercaptobutyrate).

7. The high-dielectric optical cement as claimed in claim 1, wherein the ultraviolet stabilizer is benzotriazole.

8. The high dielectric optical cement of claim 1, wherein the antioxidant is 4, 6-bis (octylthiomethyl) o-cresol.

9. A process for preparing a high dielectric optical glue according to any of claims 1 to 8, comprising the steps of:

sequentially adding the acrylate prepolymer, the acrylate diluent monomer, the photoinitiator, the chain transfer agent, the ultraviolet light stabilizer and the antioxidant into a reaction kettle, stirring and mixing for 4-5 hours at the temperature of 30-50 ℃, then defoaming for 1 hour in vacuum, standing, defoaming and storing to obtain the required optical adhesive.