An OCA optical adhesive with strong creepability, low storage modulus and self-healing function and its preparation method

Abstract

The present invention relates to the technical field of flexible OCA optical adhesives, and particularly to an OCA optical adhesive with strong creepability, low storage modulus and self-healing function and a preparation method thereof. An OCA optical adhesive with strong creepability, low storage modulus and self-healing function comprises an acrylate prepolymer, an oxime carbamate prepolymer and a first initiator; the mass ratio of the oxime carbamate prepolymer to the acrylate prepolymer is (1-5):(95-100); the oxime carbamate prepolymer is mainly prepared by reacting trimethylhexane diisocyanate with a dioxime compound. An appropriate amount of dynamically crosslinkable oxime carbamate bonds are introduced into the OCA optical adhesive of the present invention, endowing it with good self-healing ability and improving the adhesion performance of the OCA optical adhesive to the substrate, which is beneficial to improving the reworkability of the OCA optical adhesive during use, and can solve problems such as creases, bubbles, lamination delamination, etc. that occur during the long-term use of the folding display screen in a complex environment, and can effectively extend its service life.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible OCA optical adhesives, and particularly to an OCA optical adhesive with strong creepability, low storage modulus and self-healing function and a preparation method thereof. Background Art

[0002] As a new form of smart phones, foldable mobile phones have obvious advantages in providing a large-screen experience and being convenient to carry. Moreover, due to their appearance design and sense of technology, they are highly favored by consumers and gradually become the mainstream of smart phones. At present, the screen folding methods of foldable mobile phones on the market include two-axis inward folding, two-axis outward folding and water-drop folding. Flexible optically clear adhesive (OCA optical adhesive) plays a key role in the folding screen. Flexible OCA optical adhesive is an important material for bonding each functional module of the folding screen. To ensure that the folding screen remains soft and bendable after long-term bending, the flexible OCA optical adhesive needs to have good creep recovery performance and good adhesion reliability with each functional module at the same time.

[0003] The existing flexible OCA optical adhesives have a relatively high modulus. With the increase in the number of folds, it is easy to cause screen wear and crease problems. Especially at the folding place, it even leads to problems such as delamination of each display functional layer, the appearance of bubbles and dead pixels, affecting the appearance and service life. Moreover, once these problems occur in the folding screen, the repair is difficult and the repair cost is relatively high, affecting the user experience and purchase choice of consumers.

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

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a flexible OCA optical adhesive and a preparation method thereof. The OCA optical adhesive of the present invention has strong creepability, low storage modulus and excellent self-healing function, which can improve the service life and long-term reliability of the folding display screen.

[0007] To achieve the above object of the present invention, in the first aspect of the present invention, an OCA optical adhesive with strong creepability, low storage modulus and self-healing function is provided, which comprises an acrylate prepolymer, an oxime urethane prepolymer and a first initiator;

[0008] The mass ratio of the oxime urethane prepolymer to the acrylate prepolymer is (1-5):(95-100);

[0009] The oxime carbamate prepolymer is mainly prepared by reacting trimethylhexamethylene diisocyanate with a dioxime compound.

[0010] In a specific embodiment of the present invention, the trimethylhexamethylene diisocyanate includes at least one of 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate. Further, the trimethylhexamethylene diisocyanate includes 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate in a mass ratio of 1﹕(0.5 - 2).

[0011] In a specific embodiment of the present invention, the dioxime compound includes at least one of dimethylglyoxime, 2,4-pentanedione dioxime, and p-benzoquinone dioxime.

[0012] In a specific embodiment of the present invention, the molar ratio of the trimethylhexamethylene diisocyanate to the dioxime compound is 1﹕(0.95 - 1.05).

[0013] In a specific embodiment of the present invention, the acrylate prepolymer is mainly prepared by polymerizing 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 hydroxy-containing acrylate.

[0014] In a specific embodiment of the present invention, the hydroxy-containing acrylate includes at least one of 2-hydroxyethyl acrylate and 2-hydroxy-2-acrylate butyl ester.

[0015] In a specific embodiment of the present invention, the dosage of the second initiator is 0.2wt% - 1wt% of the total amount of the acrylate monomers. Further, the second initiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl propanone, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and benzoin dimethyl ether.

[0016] In a specific embodiment of the present invention, the dosage of the first initiator is 0.2wt% - 1wt% of the sum of the masses of the acrylate prepolymer and the oxime carbamate prepolymer. Further, the first initiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl propanone, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and benzoin dimethyl ether.

[0017] In a specific embodiment of the present invention, the thickness of the OCA optical adhesive is 25 - 200μm.

[0018] The second aspect of the present invention provides a method for preparing the OCA optical adhesive of the first aspect of the present invention, which comprises the following steps: mixing an acrylate prepolymer, an oxime carbamate prepolymer and a first initiator in proportion, coating into a film, and then curing by ultraviolet irradiation.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) An appropriate amount of dynamically crosslinkable oxime carbamate bonds are introduced into the OCA optical adhesive of the present invention. While ensuring the light transmittance, it 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;

[0021] (2) The preparation of the OCA optical adhesive of the present invention is simple in operation, mild in conditions, does not produce toxic and harmful substances, and is environmentally friendly;

[0022] (3) Based on the high flexibility, high bend resistance, high weather resistance, strong creepability and self-healing performance of the OCA optical adhesive of the present invention, it can solve problems such as creases, bubbles, and lamination delamination that occur during the long-term use of foldable display screens in complex environments, and can effectively extend their service life. Specific Embodiments

[0023] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified in the manufacturer are all conventional products that can be obtained through commercial purchase.

[0024] In the description of the present invention, it should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0025] The first aspect of the present invention provides an OCA optical adhesive with strong creepability, low storage modulus and self-healing function, which comprises an acrylate prepolymer, an oxime carbamate prepolymer and a first initiator;

[0026] The mass ratio of the oxime carbamate prepolymer to the acrylate prepolymer is (1-5):(95-100);

[0027] The oxime carbamate prepolymer is mainly prepared by reacting trimethylhexane diisocyanate with a dioxime compound.

[0028] An appropriate amount of dynamically crosslinkable oxime carbamate bonds is introduced into the OCA optical adhesive of the present invention. While ensuring the light transmittance, it endows the OCA optical adhesive with good self-healing ability and improves the bonding performance between the OCA optical adhesive and the substrate, which is beneficial to improving the reworkability of the OCA optical adhesive during use.

[0029] The oxime carbamate bond has a stable structure at room temperature and undergoes a reverse reaction when heated, producing free isocyanate groups (NCO) and oxime groups (NOH). The reversible dissociation and bonding endow the OCA optical adhesive with good fluidity and self-healing ability. The present invention regulates the mass ratio of the oxime carbamate prepolymer to the acrylate prepolymer to be (1-5):(95-100), for example, it can be 1:100, 1:99, 2:98, 3:97, 4:96, 5:95 or the range composed of any two of them, thereby taking into account the improvement of the self-healing performance of the OCA optical adhesive and the appropriate creep property and bonding performance. Research has found that when the dosage of the oxime carbamate prepolymer is too high, although good self-healing performance can be ensured, the excessive oxime carbamate prepolymer will cause the creep property of the OCA optical adhesive to deteriorate. The increase in crosslinking density will increase the cohesive strength, thereby enhancing its bonding strength to the substrate, resulting in the situation that the OCA optical adhesive adheres to the substrate surface; when the dosage of the oxime carbamate prepolymer is too low, the self-healing performance is poor.

[0030] The oxime carbamate prepolymer of the present invention is mainly prepared by reacting trimethylhexane diisocyanate with a dioxime compound. Trimethylhexane diisocyanate is a multi-methyl substituted aliphatic diisocyanate, and its molecular structure contains a long methylene chain segment, which has low crystallinity and can provide flexible chain segments for the polymer, so that the prepared OCA optical adhesive has high flexibility and a low storage modulus, thereby improving the bending resistance of the OCA optical adhesive.

[0031] Specifically, the oxime carbamate bond in the oxime carbamate prepolymer of the present invention has a stable structure at room temperature and undergoes a reverse reaction when heated, producing free isocyanate groups and oxime groups, which increases the density of short molecular chains and enhances the movement ability of the molecular chains; moreover, both the isocyanate group and the oxime group belong to strong polar groups. Therefore, introducing the oxime carbamate prepolymer into the OCA optical adhesive of the present invention and introducing oxime carbamate bonds into the polymer network of the OCA optical adhesive can endow it with good self-healing performance without affecting the light transmittance, and can also show good adhesiveness between the functional modules of the foldable display screen, showing high flexibility, high bending resistance, high weather resistance, strong creep property and self-healing performance, thereby effectively improving the service life of the foldable screen and maintaining the long-term reliability of daily use.

[0032] In a specific embodiment of the present invention, the trimethylhexane diisocyanate includes at least one of 2,2,4-trimethyl-hexane diisocyanate and 2,4,4-trimethyl-hexane diisocyanate. Further, the trimethylhexane diisocyanate includes 2,2,4-trimethyl-hexane diisocyanate and 2,4,4-trimethyl-hexane diisocyanate in a mass ratio of 1:(0.5 - 2).

[0033] Among them, the structural formulas of 2,2,4-trimethyl-hexane diisocyanate and 2,4,4-trimethyl-hexane diisocyanate are as follows respectively:

[0034]

[0035] In a specific embodiment of the present invention, the dioxime compound includes at least one of dimethylglyoxime, 2,4-pentanedione dioxime, and p-benzoquinone dioxime.

[0036] In a specific embodiment of the present invention, the molar ratio of the trimethylhexane diisocyanate to the dioxime compound is 1:(0.95 - 1.05), for example, it can be 1:0.95, 1:0.98, 1:1.0, 1:1.02, 1:1.05, or the range composed of any two of them.

[0037] In a specific embodiment of the present invention, the acrylate prepolymer is mainly prepared by polymerizing 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 hydroxy-containing acrylate.

[0038] In a specific embodiment of the present invention, the hydroxy-containing acrylate includes at least one of 2-hydroxyethyl acrylate and 2-hydroxy-2-butyl acrylate.

[0039] In different embodiments, by weight, the amounts of each acrylate monomer can be as follows respectively:

[0040] The amount of 2-ethylhexyl acrylate can be 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, or the range composed of any two of them;

[0041] The amount of butyl acrylate can be 5 parts, 6 parts, 8 parts, 10 parts, or the range composed of any two of them;

[0042] The amount of hydroxy-containing acrylate can be 10 parts, 14 parts, 16 parts, 20 parts, or the range composed of any two of them.

[0043] In a specific embodiment of the present invention, among the acrylate monomers, the proportion of the hydroxy-containing acrylate monomers is 10wt% - 25wt%.

[0044] In a specific embodiment of the present invention, the storage modulus of the OCA optical adhesive at -20°C < 30 KPa, and the storage modulus at 25°C < 3 KPa.

[0045] In a specific embodiment of the present invention, the creep recovery rate of the OCA optical adhesive at room temperature exceeds 90%, the maximum strain exceeds 300%, the creep recovery rate at -20°C exceeds 85%, and the maximum strain exceeds 90%.

[0046] In a specific embodiment of the present invention, the light transmittance of the OCA optical adhesive > 93%, and the haze < 0.12%.

[0047] In a specific embodiment of the present invention, the thickness of the OCA optical adhesive is 25 - 200 μm, but is not limited thereto, and 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 a range composed of any two of them.

[0048] In a specific embodiment of the present invention, the reaction of trimethylhexane diisocyanate and dioxime compound needs to be carried out under the action of a solvent and a catalyst.

[0049] In a specific embodiment of the present invention, the solvent is tetrahydrofuran; the amount of tetrahydrofuran is 50% - 100% of the total mass of the reaction system. For example, it can be 50%, 60%, 70%, 80%, 90%, 100%, or a range composed of any two of them. Among them, the total mass of the reaction system refers to the sum of the masses of trimethylhexane diisocyanate and dioxime compound.

[0050] In a specific embodiment of the present invention, the catalyst includes an organotin catalyst; the amount of the organotin catalyst is 0.02% - 0.1% of the total mass of the reaction system. For example, it can be 0.02%, 0.05%, 0.08%, 0.1%, or a range composed of any two of them.

[0051] In the present invention, the organotin catalyst used in the reaction of trimethylhexane diisocyanate and dioxime compound includes but is not limited to at least one of dibutyltin diacetate, dibutyltin dilaurate, and stannous octoate.

[0052] In a specific embodiment of the present invention, the preparation of the oxime urethane prepolymer includes: dissolving trimethylhexane diisocyanate and dioxime compound in a solvent, adding a catalyst, and reacting at 60 - 120°C under a protective atmosphere to obtain the oxime urethane prepolymer.

[0053] In different embodiments, in the preparation of the oxime carbamate prepolymer, the reaction temperature can be 60°C, 80°C, 100°C, 120°C or a range composed of any two of them. The specific reaction time is adjusted according to the infrared characteristic peak area of the isocyanate group in the reaction system, and the reaction is carried out until the infrared characteristic peak area of the isocyanate group in the reaction system no longer changes.

[0054] In a specific embodiment of the present invention, the dosage 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 of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0055] In a specific embodiment of the present invention, the preparation of the acrylate prepolymer includes: the acrylate monomers react under the action of the second initiator under a protective atmosphere under ultraviolet irradiation to obtain the acrylate prepolymer. Further, in the ultraviolet irradiation, the wavelength of the ultraviolet light is 350 to 420 nm, and the energy of the ultraviolet light is 1500 to 4000 mj / cm 2 。

[0056] In a specific embodiment of the present invention, the dosage of the first initiator is 0.2 wt% to 1 wt% of the sum of the masses of the acrylate prepolymer and the oxime carbamate prepolymer, and can be, for example, 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt% or a range composed of any two of them. Further, the first initiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and benzoin dimethyl ether.

[0057] The first initiator and the second initiator used in the present invention can be the same or different.

[0058] The second aspect of the present invention provides a method for preparing the OCA optical adhesive of the first aspect of the present invention, including the following steps: mixing the acrylate prepolymer, the oxime carbamate prepolymer, and the first initiator in proportion, coating into a film, and then curing by ultraviolet irradiation.

[0059] In a specific embodiment of the present invention, in the irradiation curing, the wavelength of the ultraviolet light is 350 to 420 nm, and can be, for example, 350 nm, 365 nm, 380 nm, 400 nm, 405 nm, 420 nm or a range composed of any two of them, and the energy of the ultraviolet light is 1500 to 4000 mj / cm 2 ,for example, it can be 1500 mj / cm 2 、2000 mj / cm 2, 2500 mj / cm 2 , 3000 mj / cm 2 , 3500 mj / cm 2 , 4000 mj / cm 2 Or the range composed of any two of them.

[0060] The coating and film-forming method of the present invention is not limited. For example, the manual coating method can be adopted, or the machine coating method can be adopted. The specific coating thickness can be adjusted conventionally according to the actual thickness requirement of the OCA optical adhesive.

[0061] The protective atmosphere involved in the present invention includes but is not limited to nitrogen atmosphere.

[0062] Some of the raw material information adopted in the following specific embodiments of the present invention can be as follows, but is not limited thereto:

[0063] Trimethylhexane diisocyanate, purity 99%, Evonik, Germany, the mass ratio of 2,2,4-trimethyl-hexane diisocyanate to 2,4,4-trimethyl-hexane diisocyanate is 1:1;

[0064] Isophorone diisocyanate, purity > 99%, Wanhua Chemical;

[0065] Dimethylglyoxime, purity > 98%, Macklin.

[0066] Tetrahydrofuran, purity > 99%, Macklin.

[0067] Before use, some raw materials can be dried and dewatered, for example, 4A molecular sieve is used for drying and dewatering.

[0068] In the preparation of the oxime carbamate prepolymer in the following embodiments of the present invention, Fourier transform infrared spectroscopy is used to qualitatively characterize the product structure; the specific instrument model is Bruker Vector 33 type FT-IR spectrometer, and the detection range is mainly between 400 and 4000 cm -1 , and the reaction degree is detected by monitoring the change of the infrared characteristic peak area of the characteristic group.

[0069] The preparation process of the oxime carbamate prepolymer involved in the following embodiments includes the following route:

[0070]

[0071] Example 1

[0072] This example provides a preparation method of OCA optical adhesive, including the following steps:

[0073] (1) Preparation of oxime carbamate prepolymer: Take 52.57 g of trimethylhexane diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reactor. The reactor is filled with 50 mL of tetrahydrofuran solution and is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a serpentine condenser. Connect the device, and introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm, and stir the reactants in the reactor evenly. Control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione monoxime to the reactor. After the butanedione monoxime is completely dissolved, take samples every 30 min until the reaction reaches the point where the area of the NCO infrared characteristic peak at 2268 cm -1 no longer changes in the infrared spectrum, then stop the reaction to obtain the oxime carbamate prepolymer.

[0074] (2) Preparation of acrylate prepolymer: Take 65 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 10 parts of 2-hydroxyethyl acrylate, 10 parts of 2-hydroxybutyl acrylate, and 0.2 part of 1-hydroxycyclohexyl phenyl ketone and add them to the reactor. The reactor is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a dry air pipeline. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm, and stir the reactants in the reactor evenly. Irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 until the reaction temperature rises by 25 - 40 °C (such as 25 °C), then stop the irradiation, close the nitrogen gas, and introduce dry air until the temperature of the polymer begins to drop to obtain the acrylate prepolymer.

[0075] (3) Preparation of OCA optical adhesive: Take 5 parts by weight of oxime carbamate prepolymer, 95 parts of acrylate prepolymer, and 0.6 part of 1-hydroxycyclohexyl phenyl ketone, mix them evenly, and perform vacuum degassing. Then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears to obtain the OCA optical adhesive with a thickness of 50 μm.

[0076] Example 2

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

[0078] (1) Preparation of oxime carbamate prepolymer: Take 52.57 g of trimethylhexane diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reactor. The reactor is filled with 50 mL of tetrahydrofuran solution and is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a serpentine condenser. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor, and at the same time start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione monoxime to the reactor. After the butanedione monoxime is completely dissolved, take samples every 30 min until the reaction stops when the area of the NCO infrared characteristic peak at 2268 cm -1 in the infrared spectrum no longer changes, and the oxime carbamate prepolymer is obtained.

[0079] (2) Preparation of acrylate prepolymer: Take 67 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 10 parts of 2-hydroxyethyl acrylate, 10 parts of 2-hydroxy-2-butyl acrylate, and 0.2 part of 1-hydroxycyclohexyl phenyl ketone and add them to the reactor. The reactor is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a dry air pipeline. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor, and at the same time start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 . When the reaction temperature rises by 25 - 40 °C (such as 25 °C), stop irradiation, close the nitrogen gas, and introduce dry air until the temperature of the polymer begins to drop, and the acrylate prepolymer is obtained.

[0080] (3) Preparation of OCA optical adhesive: Take 3 parts by weight of oxime carbamate prepolymer, 97 parts of acrylate prepolymer, and 0.6 part of 1-hydroxycyclohexyl phenyl ketone, mix them evenly, and perform vacuum degassing. Then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 . React until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears, and the OCA optical adhesive with a thickness of 50 μm is obtained.

[0081] Example 3

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

[0083] (1) Preparation of oxime carbamate prepolymer: Take 52.57 g of trimethylhexane diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reactor. The reactor is filled with 50 mL of tetrahydrofuran solution, equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline and a serpentine condenser. Connect the device well. Pass nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione monoxime to the reactor. After the butanedione monoxime is completely dissolved, take samples every 30 min until the area of the NCO infrared characteristic peak at 2268 cm -1 in the infrared spectrum no longer changes, then stop the reaction to obtain the oxime carbamate prepolymer.

[0084] (2) Preparation of acrylate prepolymer: Take 69 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 10 parts of 2-hydroxyethyl acrylate, 10 parts of 2-hydroxybutyl acrylate and 0.2 part of 1-hydroxycyclohexyl phenyl ketone and add them to the reactor. The reactor is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline and a dry air pipeline. Connect the device well. Pass nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 . When the reaction temperature rises by 25 - 40 °C (such as 25 °C), stop the irradiation, close the nitrogen gas, and pass dry air until the temperature of the polymer begins to drop to obtain the acrylate prepolymer.

[0085] (3) Preparation of OCA optical adhesive: Take 1 part of oxime carbamate prepolymer, 99 parts of acrylate prepolymer and 0.6 part of 1-hydroxycyclohexyl phenyl ketone by weight, mix them evenly, and carry out vacuum degassing. Then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 . React until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears to obtain the OCA optical adhesive with a thickness of 50 μm.

[0086] Example 4

[0087] This example provides a method for preparing OCA optical adhesive, which includes the following steps:

[0088] (1) Preparation of oxime carbamate prepolymer: Take 52.57 g of trimethylhexane diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reactor. The reactor is filled with 50 mL of tetrahydrofuran solution, equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline and a serpentine condenser. Connect the device, and introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm, stir the reactants in the reactor evenly, control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione oxime to the reactor. After the butanedione oxime is completely dissolved, take samples every 30 min until the reaction reaches the point where the area of the NCO infrared characteristic peak at 2268 cm -1 no longer changes in the infrared spectrum, then stop the reaction to obtain the oxime carbamate prepolymer.

[0089] (2) Preparation of acrylate prepolymer: Take 75 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 5 parts of 2-hydroxy-2-butyl acrylate and 0.2 part of 1-hydroxycyclohexyl phenyl ketone and add them to the reactor. The reactor is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline and a dry air pipeline. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm, stir the reactants in the reactor evenly, and irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 until the reaction temperature rises by 25 - 40 °C (such as 25 °C), then stop the irradiation, close the nitrogen gas, and introduce dry air until the temperature of the polymer begins to drop to obtain the acrylate prepolymer.

[0090] (3) Preparation of OCA optical adhesive: Take 5 parts by weight of oxime carbamate prepolymer, 95 parts of acrylate prepolymer and 0.6 part of 1-hydroxycyclohexyl phenyl ketone, mix them evenly, and perform vacuum degassing. Then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears to obtain the OCA optical adhesive with a thickness of 50 μm.

[0091] Example 5

[0092] This example provides a method for preparing OCA optical adhesive, which includes the following steps:

[0093] (1) Preparation of oxime carbamate prepolymer: Take 52.57 g of trimethylhexane diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reactor. The reactor is filled with 50 mL of tetrahydrofuran solution, equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a serpentine condenser. Connect the device, and introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione monoxime to the reactor. After the butanedione monoxime is completely dissolved, take samples every 30 min until the area of the NCO infrared characteristic peak at 2268 cm -1 in the infrared spectrum no longer changes, then stop the reaction to obtain the oxime carbamate prepolymer.

[0094] (2) Preparation of acrylate prepolymer: Take 77 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 5 parts of 2-hydroxybutyl acrylate, and 0.2 part of 1-hydroxycyclohexyl phenyl ketone and add them to the reactor. The reactor is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a dry air pipeline. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor. At the same time, start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 . When the reaction temperature rises by 25 - 40 °C (such as 25 °C), stop the irradiation, close the nitrogen gas, and introduce dry air until the temperature of the polymer begins to drop to obtain the acrylate prepolymer.

[0095] (3) Preparation of OCA optical adhesive: Take 3 parts by weight of oxime carbamate prepolymer, 97 parts of acrylate prepolymer, and 0.6 part of 1-hydroxycyclohexyl phenyl ketone, mix them evenly, and degas under vacuum. Then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 . React until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears to obtain the OCA optical adhesive with a thickness of 50 μm.

[0096] Example 6

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

[0098] (1) Preparation of oxime carbamate prepolymer: Take 52.57 g of trimethylhexane diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reactor. The reactor is filled with 50 mL of tetrahydrofuran solution, equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a serpentine condenser. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor, and at the same time start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione oxime to the reactor. After the butanedione oxime is completely dissolved, take samples every 30 min until the reaction reaches the point where the area of the NCO infrared characteristic peak at 2268 cm -1 no longer changes in the infrared spectrum, then stop the reaction to obtain the oxime carbamate prepolymer.

[0099] (2) Preparation of acrylate prepolymer: Take 79 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 5 parts of 2-hydroxy-2-butyl acrylate, and 0.2 part of 1-hydroxycyclohexyl phenyl ketone and add them to the reactor. The reactor is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a dry air pipeline. Connect the device, introduce nitrogen gas into the reactor for 10 min to displace the dissolved oxygen in the reactor, and at the same time start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reactor evenly. Irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 When the reaction temperature rises by 25 - 40 °C (such as 25 °C), stop the irradiation, close the nitrogen gas, and introduce dry air until the temperature of the polymer begins to drop to obtain the acrylate prepolymer.

[0100] (3) Preparation of OCA optical adhesive: Take 1 part of oxime carbamate prepolymer, 99 parts of acrylate prepolymer, and 0.6 part of 1-hydroxycyclohexyl phenyl ketone by weight, mix them evenly, and perform vacuum degassing. Then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears to obtain the OCA optical adhesive with a thickness of 50 μm.

[0101] Comparative Example 1

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

[0103] Step (3) of Comparative Example 1 included: taking 10 parts of oxime carbamate prepolymer, 90 parts of acrylate prepolymer, and 0.6 part of 1-hydroxycyclohexyl phenyl ketone by weight parts, mixing them evenly, degassing under vacuum, and then coating the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiating with a high-pressure UV mercury lamp at 2000 mj / cm 2 energy until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappeared, obtaining an OCA optical adhesive with a thickness of 50 μm.

[0104] Comparative Example 2

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

[0106] (1) Preparation of acrylate prepolymer: Taking 75 parts of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 5 parts of 2-hydroxy-2-butyl acrylate, and 0.2 part of 1-hydroxycyclohexyl phenyl ketone by weight parts and adding them to a reaction kettle. The reaction kettle was equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a dry air pipeline. After connecting the device, nitrogen was introduced into the reaction kettle for 10 min to displace the dissolved oxygen in the reaction kettle. At the same time, the electric stirrer was started at a rotation speed of 300 rpm to stir the reactants in the reaction kettle evenly. Irradiating with a high-pressure UV mercury lamp at 1500 mj / cm 2 energy. When the reaction temperature increased by 25 - 40 °C (such as 25 °C), the irradiation was stopped, the nitrogen was turned off, and dry air was introduced until the polymer temperature began to drop, obtaining the acrylate prepolymer.

[0107] (2) Preparation of OCA optical adhesive: Taking 100 parts of acrylate prepolymer and 0.6 part of 1-hydroxycyclohexyl phenyl ketone by weight parts, mixing them evenly, degassing under vacuum, and then coating the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiating with a high-pressure UV mercury lamp at 2000 mj / cm 2 energy until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappeared, obtaining an OCA optical adhesive with a thickness of 50 μm.

[0108] Comparative Example 3

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

[0110] (1) Preparation of acrylate prepolymer: Take 75 parts by weight of 2-ethylhexyl acrylate, 10 parts of butyl acrylate, 5 parts of 2-hydroxyethyl acrylate, 5 parts of 2-hydroxybutyl acrylate, and 0.2 parts of 1-hydroxycyclohexyl phenyl ketone and add them to a reaction kettle. The reaction kettle is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a dry air pipeline. Connect the device, introduce nitrogen into the reaction kettle for 10 minutes to displace the dissolved oxygen in the reaction kettle, and at the same time start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reaction kettle evenly. Irradiate with a high-pressure UV mercury lamp at an energy of 1500 mj / cm 2 until the reaction temperature rises by 25 - 40 °C (such as 25 °C), stop irradiation, close the nitrogen, and introduce dry air until the polymer temperature begins to drop to obtain the acrylate prepolymer.

[0111] (2) Preparation of OCA optical adhesive: Take 5 parts by weight of trimethylhexane diisocyanate, 95 parts of acrylate prepolymer, and 0.6 parts of 1-hydroxycyclohexyl phenyl ketone, mix evenly, perform vacuum degassing, and then coat the mixture between two layers of light and heavy polyethylene terephthalate (PET) release films. Irradiate with a high-pressure UV mercury lamp at an energy of 2000 mj / cm 2 until the characteristic peak of the acrylate double bond near 810 cm -1 in the infrared spectrum disappears to obtain the OCA optical adhesive with a thickness of 50 μm.

[0112] Comparative Example 4

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

[0114] Step (1) of Comparative Example 4 includes: Preparation of oxime carbamate prepolymer: Take 55.57 g of isophorone diisocyanate and 0.09 g of dibutyltin dilaurate and add them to a 250 mL four-necked jacketed reaction kettle. There is 50 mL of tetrahydrofuran solution in the reaction kettle, which is equipped with an electric stirrer, a thermometer, a nitrogen gas pipeline, and a serpentine condenser. Connect the device, introduce nitrogen into the reaction kettle for 10 minutes to displace the dissolved oxygen in the reaction kettle, and at the same time start the electric stirrer with a rotation speed of 300 rpm to stir the reactants in the reaction kettle evenly. Control the reaction temperature at 80 °C. After the temperature is constant, add 29.03 g of butanedione monoxime to the reaction kettle. After the butanedione monoxime is completely dissolved, take samples every 30 minutes until the area of the NCO infrared characteristic peak at 2268 cm -1 no longer changes, stop the reaction to obtain the oxime carbamate prepolymer.

[0115] Experimental Example

[0116] 1. Dynamic mechanical testing

[0117] (1)Storage modulus test

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

[0119] (2)Creep test

[0120] Dynamic mechanical analysis was used to test the dynamic storage modulus. The rheometer used for the test was the MCR302 rheometer from Anton Paar. During the test, the sample was cut into a suitable size, stacked with a thickness between 400 and 800 μm, a shear stress of 20 kPa was applied for 10 min, then the applied stress was removed and the sample was allowed to recover in the fixture for 10 min, so that the laminate sample was subjected to a creep test. If the creep recovery rate at room temperature (25 °C) exceeded 90% and the maximum strain exceeded 300%, and the creep recovery rate at -20 °C exceeded 85% and the maximum strain exceeded 90%, it was considered qualified. Otherwise, it was unqualified.

[0121] The results of the dynamic mechanical tests are shown in Table 1.

[0122] Table 1 Results of dynamic mechanical tests

[0123]

[0124] 2. Optical property test

[0125] The clean test glass was calibrated. The OCA optical adhesive was cut into a suitable size, the light release film was torn off and adhered to the test glass, and then the heavy release film was torn off. The transmittance and haze were tested according to the standard ASTM D1003. Each sample was repeated at least three times, and the test results were averaged. The test results are shown in Table 2.

[0126] Table 2 Results of dynamic mechanical tests

[0127]

[0128] 3. Mechanical test

[0129] (1)180° peel strength test

[0130] The cured OCA optical adhesive coated with a PET release film is cut into strips with dimensions of 100 mm × 25 mm × 150 μm (length × width × thickness) using a cutter (for the specific preparation of the OCA optical adhesive, refer to each example and comparative example to obtain strips with dimensions meeting the requirements). The light PET release film is peeled off, pasted on a PET substrate, and then the heavy release film is peeled off and pasted on a test glass. A 2 kg roller is used to roll back and forth three times at a speed of 300 mm / min, and then degassing is carried out for 30 min under the conditions of 80 °C / 0.5 MPa, and it is naturally cooled to room temperature. According to the test method for the 180° peel strength of pressure-sensitive adhesive tapes, the test is carried out with reference to GB / T 2792-1998. Each sample is repeated at least three times, and the test results are averaged.

[0131] (2)Bonding reliability inspection

[0132] The bonding reliability test is carried out by testing the high-temperature and high-humidity aging performance of the peel force test samples. According to the GBT 2423.3-2006 standard, the samples are placed in a thermostatic and humid chamber at a temperature of 85 °C and a relative humidity of 85%. After 1000 h, the appearance is observed, and the 180° peel strength test is carried out on it. Each sample is repeated at least three times, and the test results are averaged. The appearance inspection method is to inspect the appearance of the strips after the reliability experiment. The inspector visually observes at an angle of 0-90° with the finished product under a common light source (the background is black). The judgment criterion is whether there are bubbles and whether the edges turn white; if there are no bubbles and the edges do not turn white, it is qualified; otherwise, it is unqualified. The test results are shown in Table 3.

[0133] Table 3 Mechanical test results

[0134]

[0135] 4. Self-healing rate test

[0136] The self-healing performance is characterized by the restored mechanical properties, and the test standard is the same as that of the mechanical property test.

[0137] Tensile mechanical property test: The strips are cut into standard length and width, and a TH-8203A type tensile testing machine of Suzhou Tuobo Machinery Equipment Co., Ltd. is used for testing according to the GB / T 528-2009 standard. The tensile experiment is carried out at a constant rate of 100 mm / min at room temperature. Each sample is repeated at least three times, and the test results are averaged.

[0138] Self-healing rate test: When performing the self-healing performance test on this basis, cut the sample perpendicular to the tensile axis in the middle, closely contact the cross-section of the sample bar at room temperature, and then let it self-heal at 50 °C. After self-healing for different times, wait for it to cool to room temperature, and then immediately conduct a tensile experiment. Each sample is subjected to at least three tensile tests, and the test results are averaged. 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 bar. The calculation method is as follows:

[0139] Self-healing rate = ε 修复后 / ε 初始 × 100% (ε represents the elongation at break, which is the average value of 3 tests). The test results are shown in Table 4.

[0140] Table 4 Self-healing rate test results

[0141]

[0142] 5. Bending resistance test

[0143] (1) Static folding test

[0144] Remove the light and heavy PET films of the test sample, and then attach the test substrate (folding screen test module) to both sides of the sample. Set the bending angle to 180°, bend the sample into a curvature radius of approximately R = 2.5 mm, and keep it bent for 240 h under normal temperature and humidity (25 °C, 50% RH). After 240 h, observe whether the OCA optical adhesive and the test substrate maintain their original states. If there are no creases, bubbles, or delamination between the test sample and the substrate, it means the sample passes the static holding test; otherwise, it fails.

[0145] (2) Dynamic folding test

[0146] Remove the light and heavy PET films of the test sample, and then attach the test substrate (folding screen test module) to both sides of the sample. Fix the sample in the folding device, bend it from 0° to 180° at a constant rate, and conduct 150,000 cycles at a test rate of approximately 60 times per minute. The bending radius R = 2.5 mm, and the test is carried out under normal temperature and humidity (25 °C, 50% RH). After 150,000 cycles of bending, observe whether the OCA optical adhesive and the test substrate maintain their original states. If there are no creases, bubbles, or delamination between the test sample and the substrate, it means the sample passes the dynamic holding test; otherwise, it fails. The test results are shown in Table 5.

[0147] Table 5 Bending resistance test results

[0148]

[0149] According to the above test results, the low-temperature (-20°C) storage modulus of the OCA optical adhesive in the embodiments of the present invention is < 30 KPa, the room-temperature (25°C) storage modulus is < 3 KPa, and the creep recovery rate at room temperature exceeds 90%, the maximum strain exceeds 300%, the creep recovery rate at -20°C exceeds 85%, and the maximum strain exceeds 90%. Moreover, it exhibits high light transmittance, good adhesiveness, high self-healing rate, and excellent bending resistance performance.

[0150] The addition amount of the oxime carbamate prepolymer in Comparative Example 1 is relatively large, and the corresponding creep test result of the OCA optical adhesive is unqualified; moreover, during the mechanical property test, the peel strength is too large, and during the test, part of the colloid adheres to the glass substrate and cannot be peeled off, resulting in sample breakage; in the self-healing test, the corresponding test result has no significant difference from the OCA optical adhesive in the examples.

[0151] Through the comparative analysis of the test results of each example and comparative example, it can be seen that the present invention introduces an appropriate amount of dynamically crosslinkable oxime carbamate structure into the OCA optical adhesive. Without affecting the light transmittance, it not only endows it with good self-healing performance, but also exhibits good adhesiveness with the substrate, which is beneficial to improving the reworkability of the OCA optical adhesive during use. It can enable the OCA optical adhesive to have high flexibility, high bending resistance, high weather resistance, strong creepability, and self-healing performance, thereby effectively improving the service life of the OCA optical adhesive and maintaining the long-term reliability of daily use, so as to solve problems such as creases, bubbles, and delamination in the long-term use of folding screens in complex environments and effectively extend the service life.

[0152] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An OCA optical adhesive with strong creep resistance, low storage modulus and self-repairing function, characterized in that: It includes acrylate prepolymer, 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 trimethyl hexamethylene diisocyanate with a dioxime compound; the molar ratio of the trimethyl hexamethylene diisocyanate to the dioxime compound is 1: (0.95-1.05); The acrylate prepolymer is mainly prepared 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.

2. The OCA optical adhesive according to claim 1, characterized in that: 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, characterized in that: 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, characterized in that: The dioxime compound includes at least one of dimethylglyoxime, 2,4-pentanedione dioxime and p-benzoquinone dioxime.

5. The OCA optical adhesive according to claim 1, characterized in that: The hydroxyl-containing acrylate includes at least one of 2-hydroxyethyl acrylate and 2-hydroxy-2-butyl acrylate.

6. The OCA optical adhesive according to claim 1, characterized in that: The amount of the second initiator is 0.2wt% to 1wt% of the total amount of the acrylic ester monomer; The second initiator includes at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and benzoin dimethyl ether.

7. The OCA optical adhesive according to claim 1, characterized in that: The amount of the first initiator is 0.2wt% to 1wt% of the sum of the mass of the acrylate prepolymer and the oxime urethane prepolymer; The first initiator includes at least one of 1-hydroxycyclohexyl phenyl 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, characterized in that: The thickness of the OCA optical adhesive is 25-200 μm.

9. A method for preparing OCA optical adhesive, characterized in that: The method comprises the following steps: according to the composition of the OCA optical adhesive described in any one of claims 1 to 8, acrylate prepolymer, oxime urethane prepolymer and a first initiator are mixed in proportion, coated into a film, and then cured by ultraviolet radiation.

Images