Optically clear adhesive (OCA) having high creep resistance, low storage modulus and self-healing function, and preparation method therefor

Abstract

The present application relates to the technical field of flexible optically clear adhesives (OCAs), and in particular to an OCA having high creep resistance, a low storage modulus and a self-healing function, and a preparation method therefor. The OCA having high creep resistance, a low storage modulus and a self-healing function comprises an acrylate prepolymer, an oxime urethane prepolymer, and a first initiator. The mass ratio of the oxime urethane prepolymer to the acrylate prepolymer is (1-5): (95-100). The oxime urethane prepolymer is mainly prepared by reacting trimethylhexamethylene diisocyanate with a dioxime compound. The introduction of an appropriate amount of dynamically crosslinkable oxime urethane bonds into the OCA of the present application endows the OCA with a good self-healing capability, and improves the bonding performance between the OCA and a substrate, thereby improving the reworkability of the OCA during use, solving the problems of wrinkles, bubbles, interlayer delamination, etc. in foldable display screens during long-term use in complex environments, and effectively prolonging the service life of the foldable display screens.

Description

A highly creep-resistant, low-storage-modulus, and self-healing OCA optical adhesive and its preparation method thereof. Technical Field

[0001] This application relates to the field of flexible OCA optical adhesive technology, and in particular to an OCA optical adhesive with strong creep resistance, low energy storage modulus and self-healing function, and its preparation method. Background Technology

[0002] Foldable phones, as an emerging form of smartphone, offer significant advantages in providing a large-screen experience and portability. Their attractive design and futuristic appeal have made them popular with consumers, gradually becoming a mainstream smartphone technology. Currently, foldable phones on the market employ screen folding methods including two-axis inward folding, two-axis outward folding, and teardrop folding. Flexible optically clear adhesive (OCA) plays a crucial role in foldable screens. It is an important material for bonding the various functional modules of the foldable screen. To ensure that the foldable screen retains its flexibility and bendability even after prolonged bending, the flexible OCA needs to possess both good creep recovery properties and reliable adhesion to the various functional modules.

[0003] Existing flexible OCA optical adhesives have a relatively high modulus, which can easily lead to screen wear and creases with repeated folding. This is especially problematic at the folding points, where it can cause delamination of display layers, air bubbles, and dead pixels, affecting both appearance and lifespan. Furthermore, once these problems occur with foldable screens, repairs are difficult and costly, impacting user experience and purchasing decisions.

[0004] Therefore, developing an OCA optical adhesive with good bending performance and self-healing properties is of great significance for solving problems such as creases, bubbles, and delamination that occur during long-term use of foldable screens in complex environments.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0007] The purpose of this application is to provide a flexible OCA optical adhesive and its preparation method. The OCA optical adhesive of this application has strong creep resistance, low energy storage modulus and excellent self-healing function, which can improve the service life and long-term reliability of foldable display screens.

[0008] To achieve the above objectives, the first aspect of this application provides an OCA optical adhesive with strong creep resistance, low storage modulus, and self-healing function, comprising an acrylate prepolymer, an oxime urethane prepolymer, and a first initiator;

[0009] The mass ratio of the oxime prepolymer to the acrylate prepolymer is (1-5):(95-100);

[0010] The oxime ester prepolymer is mainly prepared by reacting trimethylhexanediisocyanate with a dioxime compound.

[0011] In specific embodiments of this application, the trimethyl hexamethylene diisocyanate includes at least one of 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate. Further, the trimethyl hexamethylene diisocyanate includes 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate in a mass ratio of 1:(0.5–2).

[0012] In specific embodiments of this application, the dioxime compound includes at least one of dimethylglyoxime, 2,4-pentanedione dioxime, and p-benzoquinone dioxime.

[0013] In a specific embodiment of this application, the molar ratio of the trimethylhexanediisocyanate to the dioxime compound is 1:(0.95 to 1.05).

[0014] In a specific embodiment of this application, the acrylate prepolymer is mainly obtained by polymerization of acrylate monomers under the initiation of a second initiator; the acrylate monomers include the following components by weight: 60-80 parts of 2-ethylhexyl acrylate, 5-10 parts of butyl acrylate and 10-20 parts of hydroxyl-containing acrylate.

[0015] In specific embodiments of this application, the hydroxyl-containing acrylate includes at least one of 2-hydroxyethyl acrylate and 2-hydroxy-2-butyl acrylate.

[0016] In a specific embodiment of this application, the amount of the second initiator is 0.2 wt% to 1 wt% of the total amount of the acrylate monomers. Further, the second initiator includes at least one selected from 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0017] In a specific embodiment of this application, the amount of the first initiator is 0.2 wt% to 1 wt% of the sum of the mass of the acrylate prepolymer and the oxime prepolymer. Further, the first initiator includes at least one selected from 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0018] In a specific embodiment of this application, the thickness of the OCA optical adhesive is 25–200 μm.

[0019] The second aspect of this application provides a method for preparing the OCA optical adhesive of the first aspect of this application, comprising the following steps: mixing acrylate prepolymer, oxime urethane prepolymer and a first initiator in a certain proportion, coating it into a film, and then curing it by ultraviolet irradiation.

[0020] Compared with the prior art, the beneficial effects of this application are as follows:

[0021] (1) The OCA optical adhesive of this application introduces an appropriate amount of dynamically cross-linkable oxime ester bonds, which, while ensuring light transmittance, endows the OCA optical adhesive with good self-healing ability and improves the adhesion performance between the OCA optical adhesive and the substrate, which is beneficial to improving the reworkability of the OCA optical adhesive during use.

[0022] (2) The OCA optical adhesive of this application is simple to prepare under mild conditions, does not produce toxic or harmful substances, and is environmentally friendly;

[0023] (3) Based on the high flexibility, high bending resistance, high weather resistance, strong creep and self-healing properties of the OCA optical adhesive of this application, it can solve the problems of creases, bubbles and delamination that occur in the long-term use of foldable display screens in complex environments, and can effectively extend their service life.

[0024] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0025] The technical solution of this application will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this application, not all embodiments, and are only used to illustrate this application, and should not be regarded as limiting the scope of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0026] In the description of this application, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] The first aspect of this application provides an OCA optical adhesive with strong creep resistance, low storage modulus and self-healing function, comprising an acrylate prepolymer, an oxime urethane prepolymer and a first initiator;

[0028] The mass ratio of oxime urethane prepolymer to acrylate prepolymer is (1-5):(95-100);

[0029] Oxime urethane prepolymers are mainly prepared by reacting trimethylhexanediisocyanate with dioxime compounds.

[0030] The OCA optical adhesive of this application introduces an appropriate amount of dynamically cross-linkable oxime ester bonds, which, while ensuring light transmittance, endows the OCA optical adhesive with good self-healing ability and improves the adhesion performance between the OCA optical adhesive and the substrate, thus improving the reworkability of the OCA optical adhesive during use.

[0031] The oxime ester bond is structurally stable at room temperature, but undergoes a reverse reaction upon heating to produce free isocyanate groups (NCO) and oxime groups (NOH). This reversible dissociation and bonding endows OCA optical adhesive with good flowability and self-healing ability. This application controls the mass ratio of oxime ester prepolymer to acrylate prepolymer to be (1–5):(95–100), for example, a range of 1:100, 1:99, 2:98, 3:97, 4:96, 5:95, or any combination thereof, thereby balancing improved self-healing properties with suitable creep and adhesive properties of the OCA optical adhesive. Studies have found that while excessive amounts of oxime urethane prepolymer can ensure good self-healing properties, the excessive amount of oxime urethane prepolymer will cause the creep properties of OCA optical adhesive to deteriorate. Increased crosslinking density will increase cohesive strength, thereby enhancing its adhesion strength to the substrate, resulting in OCA optical adhesive sticking to the substrate surface. When the amount of oxime urethane prepolymer is too low, the self-healing properties are poor.

[0032] The oxime prepolymer of this application is mainly prepared by reacting trimethyl hexamethylene diisocyanate with a dioxime compound. Trimethyl hexamethylene diisocyanate is a polymethyl-substituted aliphatic diisocyanate with a long methylene chain segment in its molecular structure. It has low crystallinity and can provide flexible chain segments for the polymer, so that the prepared OCA optical adhesive has high flexibility and low storage modulus, thereby improving the bending resistance of the OCA optical adhesive.

[0033] Specifically, the oxime ester bonds in the oxime ester prepolymer of this application are structurally stable at room temperature, but undergo a reverse reaction when heated to produce free isocyanate groups and oxime groups, which increases the density of short molecular chains and enhances the mobility of molecular chains. Furthermore, both isocyanate groups and oxime groups are strongly polar groups. Therefore, by introducing the oxime ester prepolymer into the OCA optical adhesive of this application and introducing oxime ester bonds into the polymer network of the OCA optical adhesive, it is possible to give it good self-healing properties without affecting the light transmittance. It can also exhibit good adhesion between the various functional modules of the foldable display screen, and exhibit high flexibility, high bending resistance, high weather resistance, strong creep and self-healing properties, thereby effectively improving the service life of the foldable screen and maintaining long-term reliability for daily use.

[0034] In specific embodiments of this application, trimethyl hexamethylene diisocyanate includes at least one of 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate. Further, trimethyl hexamethylene diisocyanate includes 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate in a mass ratio of 1:(0.5–2).

[0035] The structural formulas of 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate are as follows:

[0036] In specific embodiments of this application, the dioxime compound includes at least one of dimethylglyoxime, 2,4-pentanedione dioxime, and p-benzoquinone dioxime.

[0037] In specific embodiments of this application, the molar ratio of trimethylhexamethylene diisocyanate to the dioxime compound is 1:(0.95 to 1.05), for example, it can be a range of 1:0.95, 1:0.98, 1:0.1, 1:1.02, 1:1.05 or any two of these.

[0038] In a specific embodiment of this application, the acrylate prepolymer is mainly obtained by polymerization of acrylate monomers under the initiation of a second initiator; the acrylate monomers include the following components by weight: 60-80 parts of 2-ethylhexyl acrylate, 5-10 parts of butyl acrylate and 10-20 parts of hydroxyl-containing acrylate.

[0039] In specific embodiments of this application, the hydroxyl-containing acrylate includes at least one of 2-hydroxyethyl acrylate and 2-hydroxy-2-butyl acrylate.

[0040] In different embodiments, the amounts of each acrylate monomer, by weight, can be as follows:

[0041] The amount of 2-ethylhexyl acrylate can be 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, or any combination thereof.

[0042] The amount of butyl acrylate can be 5 parts, 6 parts, 8 parts, 10 parts, or any combination thereof.

[0043] The amount of hydroxyl-containing acrylate can be 10 parts, 14 parts, 16 parts, 20 parts, or any combination thereof.

[0044] In a specific embodiment of this application, the proportion of hydroxyl-containing acrylate monomers in the acrylate monomers is 10wt% to 25wt%.

[0045] In a specific embodiment of this application, the storage modulus of OCA optical adhesive at -20°C is <30kPa and at 25°C is <3kPa.

[0046] In the specific embodiments of this application, the room temperature creep recovery rate of OCA optical adhesive exceeds 90%, the maximum strain exceeds 300%, the -20℃ creep recovery rate exceeds 85%, and the maximum strain exceeds 90%.

[0047] In the specific embodiments of this application, the OCA optical adhesive has a light transmittance > 93% and a haze < 0.12%.

[0048] In the specific embodiments of this application, the thickness of the OCA optical adhesive is 25 to 200 μm, but is not limited to this. It can be adjusted according to actual usage requirements. For example, it can be 25 μm, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 175 μm, 200 μm or any combination thereof.

[0049] In specific embodiments of this application, the reaction between trimethylhexanediisocyanate and dioxime compounds must be carried out in the presence of a solvent and a catalyst.

[0050] In a specific embodiment of this application, the solvent is tetrahydrofuran; the amount of tetrahydrofuran used is 50% to 100% of the total mass of the reaction system, for example, it can be a range of 50%, 60%, 70%, 80%, 90%, 100%, or any two of these. The total mass of the reaction system refers to the sum of the masses of trimethylhexamethylene diisocyanate and the dioxime compound.

[0051] In a specific embodiment of this application, the catalyst includes an organotin catalyst; the amount of organotin catalyst used is 0.02% to 0.1% of the total mass of the reaction system, for example, it can be 0.02%, 0.05%, 0.08%, 0.1% or any combination thereof.

[0052] In this application, the organotin catalyst used in the reaction of trimethylhexanediisocyanate with dioxime compounds includes, but is not limited to, at least one of dibutyltin diacetate, dibutyltin dilaurate, and stannous octoate.

[0053] In a specific embodiment of this application, the preparation of the oxime ester prepolymer includes: dissolving trimethylhexanediisocyanate and a dioxime compound in a solvent, adding a catalyst, and reacting at 60–120°C under a protective atmosphere to obtain the oxime ester prepolymer.

[0054] In different embodiments, the reaction temperature in the preparation of the oxime urethane prepolymer can be 60°C, 80°C, 100°C, 120°C, or any combination thereof. The specific reaction time is adjusted according to the infrared characteristic peak area of ​​the isocyanate groups in the reaction system, and the reaction continues until the infrared characteristic peak area of ​​the isocyanate groups in the reaction system no longer changes.

[0055] In a specific embodiment of this application, the amount of the second initiator is 0.2 wt% to 1 wt% of the total amount of acrylate monomers. Further, the second initiator includes at least one selected from 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0056] In a specific embodiment of this application, the preparation of the acrylate prepolymer includes: reacting acrylate monomers under ultraviolet light irradiation in a protective atmosphere with the action of a second initiator to obtain the acrylate prepolymer. Further, in the ultraviolet light irradiation, the wavelength of the ultraviolet light is 350–420 nm, and the energy of the ultraviolet light is 1500–4000 mJ / cm². 2 .

[0057] In a specific embodiment of this application, the amount of the first initiator is 0.2 wt% to 1 wt% of the sum of the mass of the acrylate prepolymer and the oxime prepolymer, for example, it can be 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, or any combination thereof. Further, the first initiator includes at least one selected from 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0058] The first initiator and the second initiator used in this application may be the same or different.

[0059] The second aspect of this application provides a method for preparing the OCA optical adhesive of the first aspect of this application, comprising the following steps: mixing acrylate prepolymer, oxime urethane prepolymer and a first initiator in a certain proportion, coating it into a film, and then curing it by ultraviolet irradiation.

[0060] In a specific embodiment of this application, during irradiation curing, the wavelength of the ultraviolet light is 350–420 nm, for example, it can be a range of 350 nm, 365 nm, 380 nm, 400 nm, 405 nm, 420 nm, or any combination thereof, and the energy of the ultraviolet light is 1500–4000 mJ / cm². 2 For example, it can be 1500mj / cm 2 2000mj / cm 2 2500mj / cm 2 3000mj / cm 2 3500mj / cm 2 4000mj / cm 2 Or a range consisting of any two of them.

[0061] The coating method of this application is not limited. For example, it can be applied manually or by machine. The specific coating thickness can be adjusted according to the actual thickness requirements of the OCA optical adhesive.

[0062] The protective atmosphere involved in this application includes, but is not limited to, a nitrogen atmosphere.

[0063] The raw material information used in the following specific embodiments of this application may be as follows, but is not limited thereto:

[0064] Trimethylhexamethylene diisocyanate, 99% purity, Evonik, Germany, with a mass ratio of 1:1 for 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate.

[0065] Isophorone diisocyanate, purity > 99%, Wanhua Chemical;

[0066] Dimethylglyoxime, purity >98%, Maclean.

[0067] Tetrahydrofuran, purity >99%, Maclean.

[0068] Before use, some raw materials can be dried and dehydrated, for example, by using 4A molecular sieves for drying and dehydration.

[0069] In the preparation of the oxime ester prepolymers in the following embodiments of this application, Fourier transform infrared spectroscopy was used to qualitatively characterize the product structure; specifically, a Bruker Vector 33 FT-IR spectrometer was used, with a detection range mainly between 400 and 4000 cm⁻¹. -1 The degree of reaction is detected by monitoring changes in the area of ​​the infrared characteristic peaks of the characteristic groups.

[0070] The preparation process of the oxime ester prepolymer involved in the following examples includes the following route:

[0071] Example 1

[0072] This embodiment provides a method for preparing OCA optical adhesive, including the following steps:

[0073] (1) Preparation of oxime ester prepolymer: 52.57g of trimethylhexanediisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline, and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature stabilized, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, samples were taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0074] (2) Preparation of acrylate prepolymer: 65 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 10 parts by weight of 2-hydroxyethyl acrylate, 10 parts by weight of 2-hydroxy-2-butyl acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. Simultaneously, the electric stirrer was started at 300 rpm to stir the reactants in the reactor until homogeneous. A high-pressure UV mercury lamp was used at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0075] (3) Preparation of OCA optical adhesive: Take 5 parts by weight of oxime urethane prepolymer, 95 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0076] Example 2

[0077] This embodiment provides a method for preparing OCA optical adhesive, including the following steps:

[0078] (1) Preparation of oxime ester prepolymer: 52.57g of trimethylhexanediisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline, and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature stabilized, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, samples were taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0079] (2) Preparation of acrylate prepolymer: 67 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 10 parts by weight of 2-hydroxyethyl acrylate, 10 parts by weight of butyl 2-hydroxy-2-acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. Simultaneously, the electric stirrer was started at 300 rpm to stir the reactants in the reactor until homogeneous. A high-pressure UV mercury lamp was used at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0080] (3) Preparation of OCA optical adhesive: Take 3 parts by weight of oxime urethane prepolymer, 97 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0081] Example 3

[0082] This embodiment provides a method for preparing OCA optical adhesive, including the following steps:

[0083] (1) Preparation of oxime ester prepolymer: 52.57g of trimethylhexanediisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline, and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature stabilized, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, samples were taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0084] (2) Preparation of acrylate prepolymer: 69 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 10 parts by weight of 2-hydroxyethyl acrylate, 10 parts by weight of butyl 2-hydroxy-2-acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. At the same time, the electric stirrer was started at a speed of 300 rpm to stir the reactants in the reactor evenly. A high-pressure UV mercury lamp was used at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0085] (3) Preparation of OCA optical adhesive: Take 1 part by weight of oxime urethane prepolymer, 99 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0086] Example 4

[0087] This embodiment provides a method for preparing OCA optical adhesive, including the following steps:

[0088] (1) Preparation of oxime ester prepolymer: 52.57g of trimethylhexanediisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline, and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature stabilized, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, samples were taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0089] (2) Preparation of acrylate prepolymer: 75 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of 2-hydroxy-2-butyl acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. At the same time, the electric stirrer was started at a speed of 300 rpm to stir the reactants in the reactor evenly. A high-pressure UV mercury lamp was used at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0090] (3) Preparation of OCA optical adhesive: Take 5 parts by weight of oxime urethane prepolymer, 95 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0091] Example 5

[0092] This embodiment provides a method for preparing OCA optical adhesive, including the following steps:

[0093] (1) Preparation of oxime ester prepolymer: 52.57g of trimethylhexanediisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline, and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature stabilized, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, samples were taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0094] (2) Preparation of acrylate prepolymer: 77 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of 2-hydroxy-2-butyl acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. At the same time, the electric stirrer was started at a speed of 300 rpm to stir the reactants in the reactor evenly. A high-pressure UV mercury lamp was used at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0095] (3) Preparation of OCA optical adhesive: Take 3 parts by weight of oxime urethane prepolymer, 97 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0096] Example 6

[0097] This embodiment provides a method for preparing OCA optical adhesive, including the following steps:

[0098] (1) Preparation of oxime ester prepolymer: 52.57g of trimethylhexanediisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline, and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature stabilized, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, samples were taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0099] (2) Preparation of acrylate prepolymer: 79 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of 2-hydroxy-2-butyl acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. At the same time, the electric stirrer was started at a speed of 300 rpm to stir the reactants in the reactor evenly. A high-pressure UV mercury lamp was used at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0100] (3) Preparation of OCA optical adhesive: Take 1 part by weight of oxime urethane prepolymer, 99 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0101] Comparative Example 1

[0102] Comparative Example 1 refers to the preparation method of OCA optical adhesive in Example 3, the difference being that the amounts of oxime urethane prepolymer and acrylate prepolymer are different in step (3).

[0103] Step (3) of Comparative Example 1 includes: taking 10 parts by weight of oxime urethane prepolymer, 90 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mixing them evenly, degassing under vacuum, and then coating the mixture between the light and heavy layers of ethylene terephthalate (PET) release film. A high-pressure UV mercury lamp at 2000 mJ / cm² is used. 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0104] Comparative Example 2

[0105] Comparative Example 2 provides a method for preparing OCA optical adhesive, including the following steps:

[0106] (1) Preparation of acrylate prepolymer: 75 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of 2-hydroxy-2-butyl acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. At the same time, the electric stirrer was started at a speed of 300 rpm to stir the reactants in the reactor evenly. The mixture was then heated with a high-pressure UV mercury lamp at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0107] (2) Preparation of OCA optical adhesive: Take 100 parts by weight of acrylate prepolymer and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix them evenly, degas under vacuum, and then coat the mixture between the light and heavy layers of polyethylene terephthalate (PET) release film. Use a high-pressure UV mercury lamp at 2000 mJ / cm 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0108] Comparative Example 3

[0109] Comparative Example 3 provides a method for preparing OCA optical adhesive, including the following steps:

[0110] (1) Preparation of acrylate prepolymer: 75 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of 2-hydroxy-2-butyl acrylate, and 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone were added to a reactor equipped with an electric stirrer, thermometer, nitrogen pipeline, and dry air pipeline. After connecting the equipment, nitrogen gas was introduced into the reactor for 10 minutes to replace the dissolved oxygen. At the same time, the electric stirrer was started at a speed of 300 rpm to stir the reactants in the reactor evenly. The mixture was then heated with a high-pressure UV mercury lamp at 1500 mJ / cm². 2 Irradiate with energy until the reaction temperature rises to 25–40°C (e.g., 25°C), then stop irradiation, turn off the nitrogen gas, and introduce dry air until the polymer temperature begins to drop, thus obtaining the acrylate prepolymer.

[0111] (2) Preparation of OCA optical adhesive: Take 5 parts by weight of trimethylhexanediisocyanate, 95 parts by weight of acrylate prepolymer, and 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone, mix thoroughly, degas under vacuum, and then coat the mixture between two layers of ethylene terephthalate (PET) release film (light and heavy layers). Use a high-pressure UV mercury lamp at 2000 mJ / cm². 2 Energy irradiation, the reaction is shown in the infrared spectrum at 810 cm⁻¹ -1 The OCA optical adhesive with a thickness of 50 μm is obtained by continuing the process until the characteristic peaks of the nearby acrylate double bonds disappear.

[0112] Comparative Example 4

[0113] Comparative Example 4 refers to the preparation method of OCA optical adhesive in Example 1, the difference being that the preparation of the oxime ester prepolymer is different in step (1).

[0114] Step (1) of Comparative Example 4 includes: Preparation of oxime ester prepolymer: 55.57g of isophorone diisocyanate and 0.09g of dibutyltin dilaurate were added to a 250mL four-necked jacketed reactor containing 50mL of tetrahydrofuran solution. The reactor was equipped with an electric stirrer, thermometer, nitrogen pipeline and serpentine condenser. After connecting the apparatus, nitrogen gas was introduced into the reactor for 10min to replace the dissolved oxygen. At the same time, the electric stirrer was started at 300rpm to stir the reactants in the reactor evenly. The reaction temperature was controlled at 80℃. After the temperature was constant, 29.03g of dimethylglyoxime was added to the reactor. After the dimethylglyoxime was completely dissolved, a sample was taken every 30min. The reaction was carried out until the infrared spectrum reached 2268cm. -1 The reaction was stopped when the area of ​​the NCO infrared characteristic peak no longer changed, and the oxime ester prepolymer was obtained.

[0115] Experimental Example

[0116] 1. Dynamic mechanical testing

[0117] (1) Storage modulus test

[0118] Dynamic mechanical analysis is used to test the dynamic storage modulus. The rheometer used in the test is an MCR302 rheometer from Anton Paar. During the test, cut the sample into a suitable size, stack the sample to a thickness of 400~800 μm, set the temperature scanning range to -45~80°C, the heating rate to 5°C / min, the frequency to 1 Hz, and the strain to 0.1%. The shear storage modulus (G') is recorded at the selected specific temperature.

[0119] (2) Creep test

[0120] Dynamic mechanical analysis is used to test the dynamic storage modulus. The rheometer used in the test is an MCR302 rheometer from Anton Paar. During the test, cut the sample into a suitable size, stack the sample to a thickness of 400~800 μm, apply a shear stress of 20 kPa for 10 min, then remove the applied stress and allow the sample to recover in the fixture for 10 min, so that the laminate sample is subjected to a creep test. If the creep recovery rate at room temperature (25°C) exceeds 90% and the maximum strain exceeds 300%, and the creep recovery rate at -20°C exceeds 85% and the maximum strain exceeds 90%, the sample is qualified; otherwise, it is unqualified.

[0121] The dynamic mechanical test results are shown in Table 1.

[0122] Table 1 Dynamic Mechanical Test Results

[0123] 2. Optical property test

[0124] Calibrate clean test glass, cut the OCA optical adhesive to a suitable size, remove the light release film and laminate it on the test glass, then remove the heavy release film, test the transmittance and haze according to the standard ASTM D1003, repeat the test for each sample at least three times, and take the average value as the test result. The test results are shown in Table 2.

[0125] Table 2 Dynamic Mechanical Test Results

[0126] 3. Mechanical test

[0127] (1) 180° peel strength test

[0128] The OCA optical adhesive coated and cured on a PET release film is cut into strips with a size of 100mm×25mm×150μm (length×width×thickness) using a cutting knife (for the specific preparation of OCA optical adhesive, refer to each example and comparative example to obtain strips meeting the size requirements). Peel off the light PET release film and attach it to a PET substrate, then peel off the heavy release film and attach it to a test glass. Roll it back and forth three times with a 2kg roller at a speed of 300mm / min, then conduct degassing at 80°C / 0.5MPa for 30min, and cool naturally to room temperature. The test is carried out in accordance with the 180° peel strength test method for pressure-sensitive adhesive tapes and with reference to GB / T 2792-1998. Each sample is repeated at least three times, and the average value is taken as the test result.

[0129] (2) Adhesion reliability inspection

[0130] Adhesion reliability test is carried out by testing the high temperature and high humidity aging performance of the peel force test samples. According to the standard GB / T 2423.3-2006, the samples are placed in a constant temperature and humidity chamber with a temperature of 85°C and a relative humidity of 85%. After 1000 hours, the appearance is observed, and the 180° peel strength test is carried out. Each sample is repeated at least three times, and the average value is taken as the test result. The appearance inspection method is to conduct appearance inspection on the strips after the reliability test. The inspector visually inspects at an angle of 0 to 90° with the finished product under an ordinary light source with a black background, and the judgment standard is whether there are bubbles and whether the edges are whitened; if there are no bubbles and the edges are not whitened, it is qualified; otherwise, it is unqualified. The test results are shown in Table 3.

[0131] Table 3 Mechanical test results

[0132] 4. Self-healing rate test

[0133] Self-healing performance is characterized by the recovered mechanical properties, and the test standard is consistent with that of mechanical performance test.

[0134] Tensile mechanical property test: Cut the strips into standard length and width, and use the TH-8203A tensile testing machine from Suzhou Tuobo Machinery Equipment Co., Ltd. to conduct the test in accordance with the standard GB / T 528-2009. The tensile test is carried out at a constant rate of 100mm / min at room temperature. Each sample is repeated at least three times, and the average value is taken as the test result.

[0135] Self-healing rate test: To test the self-healing performance, the sample was cut along its center perpendicular to the tensile axis. The cross-sections of the sample were brought into close contact at room temperature, and then allowed to self-heal at 50°C. After different healing times, the sample was allowed to cool to room temperature and then immediately subjected to a tensile test. Each sample underwent at least three tensile tests, and the average value was taken. The self-healing rate is characterized by the ratio of the elongation at break after repair to the elongation at break of the initial sample. The calculation method is as follows:

[0136] Self-repair rate = ε 修复后 / ε 初始 ×100% (ε represents the elongation at break, which is the average of 3 tests), and the test results are shown in Table 4.

[0137] Table 4 Self-repair rate test results

[0138] 5. Bending resistance test

[0139] (1) Static folding test

[0140] Remove the light and heavy PET films from the test sample. Then, attach the test substrate (folding screen test module) to both sides of the sample. Set the bending angle to 180° and bend the sample to a radius of curvature of approximately R = 2.5 mm. Maintain this bending condition for 240 hours under normal temperature and humidity (25℃, 50% RH). After 240 hours, observe whether the OCA optical adhesive and the test substrate maintain their original state. If no creases, bubbles, or delamination appear between the test sample and the substrate, the sample passes the static retention test; otherwise, it fails.

[0141] (2) Dynamic folding test

[0142] The lightweight and heavy-duty PET films of the test samples were removed. Then, test substrates (folding screen test modules) were attached to both sides of the samples. The samples were fixed in the folding device and bent at a constant rate from 0° to 180°, undergoing 150,000 cycles at a test rate of approximately 60 times / minute. The bending radius R = 2.5 mm. The test was conducted at room temperature and humidity (25°C, 50% RH). After 150,000 bending cycles, it was observed whether the OCA optical adhesive and the test substrate maintained their original state. If no creases, bubbles, or delamination appeared between the test sample and the substrate, the sample passed the dynamic retention test; otherwise, it failed. The test results are shown in Table 5.

[0143] Table 5 Results of Bending Resistance Test

[0144] Based on the above test results, the OCA optical adhesive of this application embodiment has a low-temperature (-20℃) storage modulus of <30kPa and a room-temperature (25℃) storage modulus of <3kPa. Furthermore, it exhibits a creep recovery rate exceeding 90% and a maximum strain exceeding 300% at room temperature, and a creep recovery rate exceeding 85% and a maximum strain exceeding 90% at -20℃. It also demonstrates high light transmittance, good adhesion, high self-healing rate, and excellent flexural strength.

[0145] The addition of oxime ester prepolymer in Comparative Example 1 was too high, and the creep test results of the corresponding OCA optical adhesive were unqualified. Furthermore, during the mechanical property test, the peel strength was too high, and some adhesive adhered to the glass substrate and could not be peeled off, resulting in sample breakage. In the self-healing test, the corresponding test results were not significantly different from those of the OCA optical adhesive in the examples.

[0146] Comparative analysis of the test results of various embodiments and comparative examples shows that the present application introduces an appropriate amount of dynamically cross-linkable oxime ester structure into the OCA optical adhesive. Without affecting the light transmittance, it not only gives it good self-healing properties, but also exhibits good adhesion to the substrate. This is beneficial to improving the reworkability of the OCA optical adhesive during use. The OCA optical adhesive can achieve a combination of high flexibility, high bending resistance, high weather resistance, strong creep and self-healing properties, thereby effectively improving the service life of the OCA optical adhesive and maintaining long-term reliability in daily use. This solves the problems of creases, bubbles, and delamination that occur during long-term use of foldable screens in complex environments, and effectively extends the service life.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An OCA optical adhesive with strong creep resistance, low storage modulus and self-healing function, comprising an acrylate prepolymer, an oxime urethane prepolymer and a first initiator; The mass ratio of the oxime prepolymer to the acrylate prepolymer is (1-5):(95-100); The oxime ester prepolymer is mainly prepared by reacting trimethylhexanediisocyanate with a dioxime compound.

2. The OCA optical adhesive according to claim 1, wherein, The trimethyl hexamethylene diisocyanate includes at least one of 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate.

3. The OCA optical adhesive according to claim 1, wherein, The trimethyl hexamethylene diisocyanate comprises 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate in a mass ratio of 1:(0.5-2).

4. The OCA optical adhesive according to claim 1, wherein, The dioxime compounds include at least one of dimethylglyoxime, 2,4-pentanedione dioxime, and p-benzoquinone dioxime.

5. The OCA optical adhesive according to claim 1, wherein, The molar ratio of the trimethylhexanediisocyanate to the dioxime compound is 1:(0.95-1.05).

6. The OCA optical adhesive according to claim 1, wherein, The acrylate prepolymer is mainly obtained by polymerization of acrylate monomers under the initiation of a second initiator; the acrylate monomers include the following components by weight: 60-80 parts of 2-ethylhexyl acrylate, 5-10 parts of butyl acrylate and 10-20 parts of hydroxyl-containing acrylate. The hydroxyl-containing acrylates include at least one of 2-hydroxyethyl acrylate and 2-hydroxy-2-butyl acrylate.

7. The OCA optical adhesive according to claim 6, wherein, The amount of the second initiator is 0.2 wt% to 1 wt% of the total amount of the acrylate monomers; The second initiator includes at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

8. The OCA optical adhesive according to claim 1, wherein, The amount of the first initiator is 0.2 wt% to 1 wt% of the sum of the mass of the acrylate prepolymer and the oxime urethane prepolymer; The first initiator includes at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

9. The OCA optical adhesive according to claim 1, wherein, The thickness of the OCA optical adhesive is 25–200 μm.

10. A method for preparing OCA optical adhesive, comprising the following steps: according to the composition of OCA optical adhesive according to any one of claims 1 to 9, mixing acrylate prepolymer, oxime prepolymer and first initiator in proportion, coating into a film, and then curing by ultraviolet irradiation.

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