Optically clear adhesive (OCA) resistant to high temperature and high humidity, and preparation method therefor and use thereof

Abstract

The present application relates to the technical field of optically clear adhesives (OCAs), and in particular relates to an OCA resistant to high temperature and high humidity, and a preparation method therefor and the use thereof. The OCA resistant to high temperature and high humidity comprises 40-55 parts of a soft monomer, 10-25 parts of a hard monomer, 5-20 parts of a functional monomer, 5-15 parts of a thiourea monomer, 3-15 parts of a polyurethane acrylate prepolymer, 0.2-2 parts of a photoinitiator, 0.05-2 parts of a chain transfer agent, 0.1-1 part of a tackifying and coupling agent, 0.1-1.5 parts of an antioxidant, 0.05-1 part of a leveling agent, and 0.05-1.5 parts of a cross-linking agent, wherein the polyurethane acrylate prepolymer is mainly prepared from a polyol, a polyisocyanate and a hydroxyl-containing acrylate by means of a reaction. The OCA of the present application not only has the characteristic of high light transmittance, but also can maintain good adhesion, stability and durability in a high-temperature and high-humidity extreme environment.

Description

High-temperature and high-humidity resistant OCA optical adhesive, its preparation method and application Technical Field

[0001] This application relates to the field of optical adhesive technology, and in particular to a high-temperature and high-humidity resistant OCA optical adhesive, its preparation method, and its application. Background Technology

[0002] With the continuous development of technology, the widespread use and diversified applications of electronic products have placed higher demands on material performance. OCA optical adhesive, as a key material, is widely used in displays of various products such as smartphones, tablets, electronic watches, and automobiles. As the importance of these devices in daily life continues to increase, and the operating environments become increasingly complex, many devices need to operate under high temperature and humidity conditions. Therefore, the market demand for OCA optical adhesives with superior optical performance, adhesion, and durability under extreme environments such as high temperature and humidity is constantly increasing. Traditional optical adhesives are prone to problems such as yellowing, blistering, or delamination under these extreme environments, affecting display quality and device lifespan. Furthermore, traditional optical adhesives may contain volatile organic compounds (VOCs) and other harmful substances, which not only pollute the environment but also pose a potential threat to human health. Therefore, developing environmentally friendly OCA optical adhesives that can maintain excellent performance under high temperature and humidity conditions has become an urgent need in the industry.

[0003] In view of the above, this application is hereby submitted. Summary of the Invention

[0004] 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.

[0005] The purpose of this application is to provide a high-temperature and high-humidity resistant OCA optical adhesive, its preparation method and application. The OCA optical adhesive of this application has excellent high-temperature and high-humidity resistance and maintains good optical performance, adhesion performance and aging resistance under high-temperature and high-humidity conditions.

[0006] To achieve the above-mentioned objectives of this application, the first aspect of this application provides a high-temperature and high-humidity resistant OCA optical adhesive, comprising the following components by weight: 40-55 parts of soft monomer, 10-25 parts of hard monomer, 5-20 parts of functional monomer, 5-15 parts of thiourea monomer, 3-15 parts of polyurethane acrylate prepolymer, 0.2-2 parts of photoinitiator, 0.05-2 parts of chain transfer agent, 0.1-1 parts of tackifying coupling agent, 0.1-1.5 parts of antioxidant, 0.05-1 parts of leveling agent, and 0.05-1.5 parts of crosslinking agent;

[0007] The polyurethane acrylate prepolymer is mainly prepared by reacting polyols, polyisocyanates and hydroxyl-containing acrylates; the polyols include polytetrahydrofuran ether diol and polycaprolactone diol, and the polyisocyanates include isophorone diisocyanate and hexamethylene diisocyanate.

[0008] In a specific embodiment of this application, the molar ratio of the polytetrahydrofuran ether diol and the polycaprolactone diol in the polyol is 1:(0.5-2).

[0009] In a specific embodiment of this application, the molar ratio of isophorone diisocyanate to hexamethylene diisocyanate in the polyisocyanate is 1:(0.5-2).

[0010] In a specific embodiment of this application, the molar ratio of the polyol to the polyisocyanate is 1:(1.2 to 1.5).

[0011] In a specific embodiment of this application, the molar ratio of the polyol to the hydroxyl-containing acrylate is 1:(0.8-1.2). Further, the hydroxyl-containing acrylate includes at least one of 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and hydroxypropyl acrylate.

[0012] In a specific embodiment of this application, the preparation of the polyurethane acrylate prepolymer is carried out in the presence of a catalyst. Further, the catalyst includes at least one selected from dibutyltin dilaurate, triethylenediamine, and stannous octoate.

[0013] In a specific embodiment of this application, the raw materials used in the preparation of the polyurethane acrylate prepolymer also include chain extenders and / or fillers.

[0014] In a specific embodiment of this application, the amount of the chain extender is 0.5 wt% to 2 wt% of the total amount of the polyol, the polyisocyanate, and the hydroxyl-containing acrylate. Further, the chain extender is 1,4-butanediol and / or 1,6-hexanediol.

[0015] In a specific embodiment of this application, the amount of the filler is 8 wt% to 12 wt% of the total amount of the polyol, the polyisocyanate, and the hydroxyl-containing acrylate. Further, the filler is at least one of nanocellulose, nanoalumina, and nanosilica; the particle size of the filler is 1 to 50 nm.

[0016] In specific embodiments of this application, the thiourea monomer includes at least one of 1,3-diallyl-2-thiourea, allyl thiourea, 1-allyl-3-(4-benzylphenyl)thiourea, 1-allyl-3-(pyridin-3-yl)thiourea, 1-allyl-3,3-diethyl-2-thiourea, 1-methylallyl-3-methyl-2-thiourea, and N-propene N'-2-hydroxyethylthiourea.

[0017] In a specific embodiment of this application, the mass ratio of the thiourea monomer to the polyurethane acrylate prepolymer is (0.5-3):1.

[0018] In a specific embodiment of this application, the glass transition temperature of the soft monomer is -60 to -10°C. Further, the soft monomer includes at least one selected from ethyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, butyl acrylate, and isooctyl acrylate.

[0019] In specific embodiments of this application, the hard monomer includes at least one of methyl acrylate, methyl methacrylate, isobornyl acrylate, ethyl methacrylate, styrene, and acrylonitrile.

[0020] In specific embodiments of this application, the functional monomer includes at least one of acrylic acid, acrylamide, N,N-dimethylacrylamide, hydroxyethyl acrylate, and hydroxybutyl acrylate.

[0021] In specific embodiments of this application, the crosslinking agent includes at least one of diethylene glycol diacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate.

[0022] The second aspect of this application provides a method for preparing the high-temperature and high-humidity resistant OCA optical adhesive provided in the first aspect of this application, comprising the following steps: mixing soft monomers, hard monomers, functional monomers, thiourea monomers, polyurethane acrylate prepolymers and photoinitiators evenly, irradiating with ultraviolet light for 3-5 minutes, then adding chain transfer agents, tackifying coupling agents, antioxidants, leveling agents and crosslinking agents and mixing evenly, coating and curing with ultraviolet light.

[0023] In a specific embodiment of this application, the thickness of the OCA optical adhesive is 50–300 μm.

[0024] The third aspect of this application provides the application of the high-temperature and high-humidity resistant OCA optical adhesive provided in the first aspect of this application in a display screen.

[0025] Compared with the prior art, the beneficial effects of this application are as follows:

[0026] (1) The OCA optical adhesive of this application not only has the characteristic of high light transmittance, but also maintains good adhesion, stability and durability in extreme environments of high temperature and high humidity. It can prevent blistering or delamination caused by water vapor penetration and is not prone to deformation or failure.

[0027] (2) The OCA optical adhesive of this application does not require the use of organic solvents and the preparation method is simple, which meets the dual requirements of high performance and environmental protection.

[0028] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0029] 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.

[0030] The first aspect of this application provides a high-temperature and high-humidity resistant OCA optical adhesive, comprising the following components by weight: 40-55 parts of soft monomer, 10-25 parts of hard monomer, 5-20 parts of functional monomer, 5-15 parts of thiourea monomer, 3-15 parts of polyurethane acrylate prepolymer, 0.2-2 parts of photoinitiator, 0.05-2 parts of chain transfer agent, 0.1-1 part of tackifying coupling agent, 0.1-1.5 parts of antioxidant, 0.05-1 part of leveling agent, and 0.05-1.5 parts of crosslinking agent;

[0031] Polyurethane acrylate prepolymers are mainly prepared by reacting polyols, polyisocyanates and hydroxyl-containing acrylates; the polyols include polytetrahydrofuran ether diol and polycaprolactone diol, and the polyisocyanates include isophorone diisocyanate and hexamethylene diisocyanate.

[0032] The OCA optical adhesive of this application not only has the characteristic of high light transmittance, but also maintains good adhesion, stability and durability in extreme environments of high temperature and high humidity. It can prevent blistering or delamination caused by water vapor penetration and is not prone to deformation or failure.

[0033] The OCA optical adhesive of this application incorporates a certain amount of thiourea monomer and polyurethane acrylate prepolymer. The addition of polyurethane acrylate prepolymer introduces polyurethane segments with excellent thermal stability and hydrolysis resistance into the OCA optical adhesive system. Furthermore, the acrylate segments polymerize with various monomers to form a cross-linked network structure. Combined with the increased hydrophobic groups and intermolecular hydrogen bonding introduced by the thiourea monomer, the high temperature and high humidity resistance of the OCA optical adhesive is significantly improved while maintaining its high light transmittance.

[0034] This application adjusts the formulation based on the above-mentioned components to balance the high light transmittance and high temperature and humidity resistance of the OCA optical adhesive. For example, in different embodiments, the amounts of each component in the high temperature and humidity resistant OCA optical adhesive, by weight, can be as follows:

[0035] The amount of soft monomer can be 40 parts, 42 parts, 45 parts, 48 ​​parts, 50 parts, 52 parts, 55 parts, or any combination thereof;

[0036] The amount of hard monomer can be 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, or any combination thereof;

[0037] The amount of functional monomer can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, or any combination thereof;

[0038] The amount of thiourea monomer can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, or any combination thereof;

[0039] The amount of polyurethane acrylate prepolymer can be 3 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, or any combination thereof.

[0040] The amount of photoinitiator can be 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0041] The amount of chain transfer agent can be 0.05 parts, 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, or any combination thereof;

[0042] The amount of the thickening coupling agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof;

[0043] The amount of antioxidant can be 0.1 parts, 0.5 parts, 1 part, 1.5 parts, or any combination thereof;

[0044] The amount of leveling agent can be 0.05 parts, 0.1 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof;

[0045] The amount of crosslinking agent can be 0.05 parts, 0.1 parts, 0.5 parts, 1 part, 1.5 parts, or any combination thereof.

[0046] In a specific embodiment of this application, the molar ratio of polytetrahydrofuran ether diol and polycaprolactone diol in the polyol is 1:(0.5-2), for example, it can be a range of 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2 or any two of them, which helps to improve the high temperature and high humidity resistance and adhesive properties of OCA optical adhesive.

[0047] In the specific embodiments of this application, the number average molecular weight of polytetrahydrofuran ether diol is 1000-3000; the number average molecular weight of polycaprolactone diol is 1000-3000.

[0048] In a specific embodiment of this application, the molar ratio of isophorone diisocyanate and hexamethylene diisocyanate in the polyisocyanate is 1:(0.5-2), for example, it can be a range of 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2 or any two of them, which helps to improve the high temperature and high humidity resistance and adhesion performance of OCA optical adhesive.

[0049] In specific embodiments of this application, the molar ratio of polyol to polyisocyanate is 1:(1.2 to 1.5), for example, it can be a range of 1:1.2, 1:1.3, 1:1.4, 1:1.5 or any two of them.

[0050] In specific embodiments of this application, the molar ratio of the polyol to the hydroxyl-containing acrylate is 1:(0.8 to 1.2), for example, it can be a range of 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, or any two of these. Further, the hydroxyl-containing acrylate includes at least one of 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and hydroxypropyl acrylate.

[0051] In a specific embodiment of this application, the preparation of the polyurethane acrylate prepolymer is carried out in the presence of a catalyst. Further, the catalyst includes at least one selected from dibutyltin dilaurate, triethylenediamine, and stannous octoate. In practice, the catalyst is used in conventional amounts, for example, the amount of catalyst can be 0.02 wt% to 1 wt% of the total reactants.

[0052] In a specific embodiment of this application, the raw materials for preparing the polyurethane acrylate prepolymer also include chain extenders and / or fillers.

[0053] In a specific embodiment of this application, the chain extender is used in an amount of 0.5 wt% to 2 wt% of the total amount of polyol, polyisocyanate, and hydroxyl-containing acrylate, for example, in the range of 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, or any combination thereof, thereby further improving the crosslinking network structure in the OCA optical adhesive and improving its resistance to high temperature and high humidity. Further, the chain extender is 1,4-butanediol and / or 1,6-hexanediol.

[0054] In a specific embodiment of this application, the amount of filler is 8 wt% to 12 wt% of the total amount of polyol, polyisocyanate, and hydroxyl-containing acrylate, for example, it can be 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, or any combination thereof, which helps to balance the high light transmittance and high temperature and humidity resistance of the OCA optical adhesive. Furthermore, the filler is at least one of nanocellulose, nanoalumina, and nanosilica, and the particle size of the filler is 1 to 50 nm.

[0055] In a specific embodiment of this application, the preparation of polyurethane acrylate prepolymer includes: reacting polyol and polyisocyanate at 65-75°C for 2-4 hours under the action of a catalyst, then adding hydroxyl-containing acrylate, filler and chain extender, and continuing to react at 65-75°C for 2-3 hours to obtain polyurethane acrylate prepolymer.

[0056] In specific embodiments of this application, the thiourea monomer includes at least one of 1,3-diallyl-2-thiourea, allyl thiourea, 1-allyl-3-(4-benzylphenyl)thiourea, 1-allyl-3-(pyridin-3-yl)thiourea, 1-allyl-3,3-diethyl-2-thiourea, 1-methylallyl-3-methyl-2-thiourea, and N-propene N'-2-hydroxyethylthiourea.

[0057] In a specific embodiment of this application, the mass ratio of thiourea monomer to polyurethane acrylate prepolymer is (0.5-3):1, for example, it can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and further optionally (1-2.5):1, which helps to improve the high temperature and high humidity resistance, etc.

[0058] In a specific embodiment of this application, the glass transition temperature of the soft monomer is -60 to -10°C. Further, the soft monomer includes at least one selected from ethyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, butyl acrylate, and isooctyl acrylate.

[0059] In specific embodiments of this application, the hard monomer includes at least one of methyl acrylate, methyl methacrylate, isobornyl acrylate, ethyl methacrylate, styrene, and acrylonitrile.

[0060] In specific embodiments of this application, the functional monomer includes at least one of acrylic acid, acrylamide, N,N-dimethylacrylamide, hydroxyethyl acrylate, and hydroxybutyl acrylate.

[0061] In specific embodiments of this application, the photoinitiator includes, but is not limited to, at least one of benzophenone, benzoyl dimethyl ether, methyl benzoylformate, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxy-cyclohexylbenzophenone, 2,4-diethylthioxanthone, and α-hydroxyisobutyrophenyl.

[0062] In specific embodiments of this application, the chain transfer agent includes, but is not limited to, at least one of thioglycolic acid, dodecyl mercaptohydric acid, isooctyl mercaptoacetate, 2-mercaptoethanol, isooctyl 3-mercaptopropionate, and pentaerythritol tetra(3-mercaptobutyrate).

[0063] In specific embodiments of this application, the thickening coupling agent includes, but is not limited to, at least one of vinyltriethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, methyldimethoxysilane, and methyltriethoxysilane.

[0064] In specific embodiments of this application, the antioxidants include, but are not limited to, at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis-(4-methyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-thiobis(6-tert-butyl-3-methylphenol), and N,N-diphenyl-p-phenylenediamine.

[0065] In specific embodiments of this application, the leveling agent includes, but is not limited to, at least one of Troysol S366, Modaflow 2100, TEGO Glide 435, BYK370, BYK333, TEGO Flow ZFS 460, and Perenol S71UV.

[0066] In specific embodiments of this application, the crosslinking agent includes at least one of diethylene glycol diacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate.

[0067] The second aspect of this application provides a method for preparing the high-temperature and high-humidity resistant OCA optical adhesive provided in the first aspect of this application, comprising the following steps: mixing soft monomers, hard monomers, functional monomers, thiourea monomers, polyurethane acrylate prepolymers and photoinitiators evenly, and then irradiating with ultraviolet light for 3 to 5 minutes; then adding chain transfer agents, tackifying coupling agents, antioxidants, leveling agents and crosslinking agents, mixing evenly, coating and curing with ultraviolet light.

[0068] In a specific embodiment of this application, the wavelength of ultraviolet light irradiation can be 280–420 nm.

[0069] In the specific embodiments of this application, the energy in the ultraviolet curing process is 2500–3500 mJ / cm². 2 For example, it can be 2500mj / cm 2 2800mj / cm 2 3000mj / cm 2 3200mj / cm 2 3500mj / cm 2 Or a range consisting of any two of them.

[0070] In the specific embodiments of this application, the thickness of the OCA optical adhesive is 50 to 300 μm, for example, it can be 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm or any combination thereof. The specific thickness range can be adjusted according to actual needs. Within this thickness range, both high light transmittance and high temperature and humidity resistance can be taken into account.

[0071] In a specific embodiment of this application, curing with ultraviolet light after coating includes: coating the mixture on the release surface of the heavy release film, then attaching the light release film, and then curing with ultraviolet light.

[0072] In practice, coating can be done using conventional methods, either manually or with a coating machine.

[0073] In specific embodiments of this application, the thicknesses of the heavy release film and the light release film are each independently selected from 50 to 100 μm, for example, they can be 50 μm, 60 μm, 75 μm, 80 μm, 90 μm, 100 μm or any combination thereof.

[0074] In a specific embodiment of this application, the release force of the heavy release film is 20-40 gf / in, and the release force of the light release film is 3-10 gf / in.

[0075] The third aspect of this application provides the application of the high-temperature and high-humidity resistant OCA optical adhesive provided in the first aspect of this application in a display screen.

[0076] Example 1

[0077] This embodiment provides a high-temperature and high-humidity resistant OCA optical adhesive, comprising the following components by weight: 45 parts lauryl acrylate, 19 parts isobornyl acrylate, 15 parts hydroxybutyl acrylate, 15 parts allyl thiourea, 5 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0078] The preparation method of the polyurethane acrylate prepolymer includes: adding 100g of polycaprolactone diol with a number average molecular weight of 2000 and 100g of polytetrahydrofuran ether diol with a number average molecular weight of 2000 to an oxygen-free reactor, then adding polyisocyanate, wherein the total molar ratio of polycaprolactone diol to polytetrahydrofuran ether diol to the molar ratio of polyisocyanate is 1:1.3, heating to 70℃, then adding 0.2g of dibutyltin dilaurate, and reacting for 2.5h under stirring; then adding 11.612g of 2-hydroxyethyl acrylate, nanocellulose (average particle size of 10nm), and 1,4-butanediol, and continuing to stir and react at 70℃ for 2h, cooling to room temperature, and storing in a sealed, light-protected container. The polyisocyanate is hexamethylene diisocyanate and isophorone diisocyanate in a molar ratio of 1:1. The amount of nanocellulose added is 10 wt% of the total amount of polycaprolactone diol, polytetrahydrofuran ether diol, polyisocyanate and 2-hydroxyethyl acrylate. The amount of 1,4-butanediol added is 1 wt% of the total amount of polycaprolactone diol, polytetrahydrofuran ether diol, polyisocyanate and 2-hydroxyethyl acrylate.

[0079] This embodiment provides a method for preparing high-temperature and high-humidity resistant OCA optical adhesive, including the following steps:

[0080] The soft monomer lauryl acrylate, the hard monomer isobornyl acrylate, the functional monomer hydroxybutyl acrylate, the thiourea monomer allyl thiourea, the polyurethane acrylate prepolymer, and the photoinitiator were mixed evenly and then irradiated with 365nm ultraviolet light for 4 min. Then, the chain transfer agent dodecyl mercaptan, the tackifying coupling agent vinyltriethoxysilane, the antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], the leveling agent Modaflow, and the crosslinking agent triethylene glycol diacrylate were added and mixed evenly to obtain a mixture. The mixture was then coated onto the release surface of a 75μm thick heavy release film (release force of 30gf / in), and then a light release film (release force of 5gf / in) was attached. Finally, the mixture was irradiated with 365nm ultraviolet light at a total energy of 3000mJ / cm. 2The OCA optical adhesive was cured by ultraviolet light and obtained with a thickness of 200 μm.

[0081] Example 2

[0082] This embodiment refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1. The only difference is that the amount of each component is different and the type of thiourea monomer is different.

[0083] The high-temperature and high-humidity resistant OCA optical adhesive of this embodiment comprises the following components by weight: 47 parts lauryl acrylate, 17 parts isobornyl acrylate, 15 parts hydroxybutyl acrylate, 12 parts 1-allyl-3-(4-benzylphenyl)thiourea, 8 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0084] Example 3

[0085] This embodiment refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1. The only difference is that the amount of each component is different and the type of thiourea monomer is different.

[0086] The high-temperature and high-humidity resistant OCA optical adhesive of this embodiment comprises the following components by weight: 50 parts lauryl acrylate, 20 parts isobornyl acrylate, 14 parts hydroxybutyl acrylate, 10 parts 1-allyl-3-(4-benzylphenyl)thiourea, 5 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0087] Example 4

[0088] This embodiment refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1. The only difference is that the amount of each component is different and the type of thiourea monomer is different.

[0089] The high-temperature and high-humidity resistant OCA optical adhesive of this embodiment comprises the following components by weight: 45 parts lauryl acrylate, 20 parts isobornyl acrylate, 14 parts hydroxybutyl acrylate, 10 parts 1-allyl-3-(4-benzylphenyl)thiourea, 10 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0090] Example 5

[0091] This embodiment refers to the high-temperature and high-humidity resistant OCA optical adhesive and its preparation method in Example 4, the only difference being the amount of thiourea monomer and polyurethane acrylate prepolymer used.

[0092] In this embodiment, the amount of thiourea monomer 1-allyl-3-(4-benzylphenyl)thiourea is 5 parts, and the amount of polyurethane acrylate prepolymer is 15 parts.

[0093] Example 6

[0094] This embodiment refers to the high-temperature and high-humidity resistant OCA optical adhesive and its preparation method in Example 4, the only difference being the amount of thiourea monomer and polyurethane acrylate prepolymer used.

[0095] In this embodiment, the amount of thiourea monomer 1-allyl-3-(4-benzylphenyl)thiourea is 15 parts, and the amount of polyurethane acrylate prepolymer is 5 parts.

[0096] Comparative Example 1

[0097] Comparative Example 1 refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1, the difference being that the amount of each component is different, and it does not include thiourea monomer and polyurethane acrylate prepolymer.

[0098] The OCA optical adhesive of Comparative Example 1 comprises the following components by weight: 55 parts lauryl acrylate, 25 parts isobornyl acrylate, 19 parts hydroxybutyl acrylate, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0099] Comparative Example 2

[0100] Comparative Example 2 refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1, the difference being that the amount of each component is different and the polyurethane acrylate prepolymer is different.

[0101] Comparative Example 2's OCA optical adhesive comprises the following components by weight: 50 parts lauryl acrylate, 20 parts isobornyl acrylate, 14 parts hydroxybutyl acrylate, 10 parts 1-allyl-3-(4-benzylphenyl)thiourea, 5 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0102] The preparation method of the polyurethane acrylate prepolymer is the same as that of the polyurethane acrylate prepolymer in Example 1, except that: 200g of polycaprolactone diol with a number average molecular weight of 2000 is used to replace 100g of polycaprolactone diol with a number average molecular weight of 2000 and 100g of polytetrahydrofuran ether diol with a number average molecular weight of 2000 in Example 1; and hexamethylene diisocyanate and isophorone diisocyanate are replaced in equal molar amounts in Example 1.

[0103] Comparative Example 3

[0104] Comparative Example 3 refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1, the difference being that the amount of each component is different and the polyurethane acrylate prepolymer is different.

[0105] Comparative Example 3's OCA optical adhesive comprises the following components by weight: 50 parts lauryl acrylate, 20 parts isobornyl acrylate, 14 parts hydroxybutyl acrylate, 10 parts 1-allyl-3-(4-benzylphenyl)thiourea, 5 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0106] The preparation method of the polyurethane acrylate prepolymer is the same as that of the polyurethane acrylate prepolymer in Example 1, except that: 200g of polytetrahydrofuran ether diol with a number average molecular weight of 2000 is used to replace 100g of polycaprolactone diol with a number average molecular weight of 2000 and 100g of polytetrahydrofuran ether diol with a number average molecular weight of 2000 in Example 1; and hexamethylene diisocyanate and isophorone diisocyanate are replaced in equal molar amounts in Example 1.

[0107] Comparative Example 4

[0108] Comparative Example 4 refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1, the difference being that the amount of each component is different and the polyurethane acrylate prepolymer is different.

[0109] Comparative Example 4's OCA optical adhesive comprises the following components by weight: 50 parts lauryl acrylate, 20 parts isobornyl acrylate, 14 parts hydroxybutyl acrylate, 10 parts 1-allyl-3-(4-benzylphenyl)thiourea, 5 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0110] The preparation method of the polyurethane acrylate prepolymer is the same as that of the polyurethane acrylate prepolymer in Example 1, except that hexamethylene diisocyanate and isophorone diisocyanate in Example 1 are replaced by an equal molar amount of hexamethylene diisocyanate.

[0111] Comparative Example 5

[0112] Comparative Example 5 refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1, the difference being that the amount of each component is different and it does not include polyurethane acrylate prepolymer.

[0113] Comparative Example 5, the OCA optical adhesive, comprises the following components by weight: 53 parts lauryl acrylate, 21 parts isobornyl acrylate, 15 parts hydroxybutyl acrylate, 10 parts 1-allyl-3-(4-benzylphenyl)thiourea, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0114] Comparative Example 6

[0115] Comparative Example 6 refers to the high temperature and high humidity resistant OCA optical adhesive and its preparation method in Example 1, the difference being that the amount of each component is different and it does not include polyurethane acrylate prepolymer.

[0116] Comparative Example 6, the OCA optical adhesive, comprises the following components by weight: 55 parts lauryl acrylate, 23 parts isobornyl acrylate, 16 parts hydroxybutyl acrylate, 5 parts polyurethane acrylate prepolymer, 0.3 parts photoinitiator methyl benzoate, 0.09 parts dodecyl mercaptan, 0.2 parts vinyltriethoxysilane, 0.11 parts antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 0.2 parts leveling agent Modaflow 2100, and 0.1 parts triethylene glycol diacrylate.

[0117] Experimental Example

[0118] The following performance tests were conducted on the OCA optical adhesives of different embodiments and comparative examples. The test results are shown in Table 1.

[0119] Optical performance testing: The 7-inch glass cover plate / OCA optical adhesive / matching ITO sheet are bonded together, and then tested according to GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics".

[0120] Gel content test: OCA optical adhesive was cut into small pieces of roughly the same size, and half of them were subjected to 5000mj / cm 2 After post-curing, the OCA optical adhesive was wound around a glass rod, and the initial mass of the OCA optical adhesive was recorded as Ms. It was then placed in a beaker containing 250 mL of ethyl acetate. After 24 hours, the solvent was filtered out using a 300-mesh filter. The remaining OCA optical adhesive was then dried in an oven at 120°C for 30 minutes, and its remaining weight was recorded as Me. The gel content (G) was calculated using the following formula: G = Me / Ms.

[0121] Table 1. Performance test results of various OCA optical adhesives

[0122] As can be seen from the test results in Table 1, the OCA optical adhesive of this application has good optical properties and cross-linking effect.

[0123] Further performance tests were conducted on the OCA optical adhesives of different embodiments and comparative examples, and the test results are shown in Table 2.

[0124] Adhesion test: Tear off the light release film of each OCA optical adhesive and attach it to a 50μm transparent PET film. Use a manual sampler to cut it into samples with a width of 25.4mm and a length of 200mm. Tear off the heavy release film and attach it to a SUS 304 steel plate. Roll it back and forth 3 times with a 2kg roller at a speed of 600mm / min. Place it in environments of 25℃, 60℃, 90℃, 60℃ / 90%RH and 85℃ / 85%RH for 20min respectively. Use a tensile testing machine to test its 180° peel adhesion.

[0125] Table 2. Peel strength test results of various OCA optical adhesives under different conditions.

[0126] As can be seen from the test results in Table 2, the OCA optical adhesive of this application has excellent resistance to high temperature and high humidity, and can maintain good cohesion and higher adhesion under high temperature and high humidity conditions.

[0127] Further tests were conducted on the aging resistance of the OCA optical adhesives in different embodiments and comparative examples. The test results are shown in Table 3.

[0128] Aging resistance test: Each OCA optical adhesive was bonded to a glass cover plate, and after degassing, it underwent a total energy test of 3000mJ / cm. 2 The LED lights were treated and then placed in environments of 25℃, 90℃, 110℃, 85℃ / 85%RH and 110℃ / 90%RH for 1000 hours respectively. During this period, the samples were observed for the presence of bubbles or other phenomena. If present, it was marked ×; otherwise, it was marked √.

[0129] Table 3. Aging resistance test results of various OCA optical adhesives

[0130] As can be seen from the test results in Table 3, the OCA optical adhesive of this application has excellent aging resistance and does not exhibit bubble rebound or delamination in high temperature and high humidity environments.

[0131] In summary, the OCA optical adhesive of this application has a light transmittance of over 90%, a haze of <1, and does not exhibit any bubble rebound or delamination after being kept in a high temperature and high humidity environment (temperature 100-150℃, humidity 60%-90%) for 1000 hours, demonstrating excellent high temperature and high humidity resistance.

[0132] 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. High-temperature and high-humidity resistant OCA optical adhesive, comprising the following components by weight: 40-55 parts soft monomer, 10-25 parts hard monomer, 5-20 parts functional monomer, 5-15 parts thiourea monomer, 3-15 parts polyurethane acrylate prepolymer, 0.2-2 parts photoinitiator, 0.05-2 parts chain transfer agent, 0.1-1 part tackifying coupling agent, 0.1-1.5 parts antioxidant, 0.05-1 part leveling agent, and 0.05-1.5 parts crosslinking agent; The polyurethane acrylate prepolymer is mainly prepared by reacting polyols, polyisocyanates and hydroxyl-containing acrylates; the polyols include polytetrahydrofuran ether diol and polycaprolactone diol, and the polyisocyanates include isophorone diisocyanate and hexamethylene diisocyanate.

2. The high-temperature and high-humidity resistant OCA optical adhesive according to claim 1, wherein, In the polyol, the molar ratio of the polytetrahydrofuran ether diol and the polycaprolactone diol is 1:(0.5-2).

3. The high-temperature and high-humidity resistant OCA optical adhesive according to claim 1, wherein, In the polyisocyanate, the molar ratio of isophorone diisocyanate to hexamethylene diisocyanate is 1:(0.5-2).

4. The high-temperature and high-humidity resistant OCA optical adhesive according to claim 1, wherein, It has at least one of the following characteristics: (1) The molar ratio of the polyol to the polyisocyanate is 1:(1.2 to 1.5); (2) The molar ratio of the polyol to the hydroxyl-containing acrylate is 1:(0.8-1.2); (3) The hydroxyl-containing acrylate includes at least one of 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate and hydroxypropyl acrylate; (4) The preparation of the polyurethane acrylate prepolymer is carried out in the presence of a catalyst; the catalyst includes at least one of dibutyltin dilaurate, triethylenediamine and stannous octoate. (5) In the preparation of the polyurethane acrylate prepolymer, the raw materials also include chain extenders and / or fillers.

5. The high-temperature and high-humidity resistant OCA optical adhesive according to claim 1, wherein, The thiourea monomer includes at least one selected from 1,3-diallyl-2-thiourea, allyl thiourea, 1-allyl-3-(4-benzylphenyl)thiourea, 1-allyl-3-(pyridin-3-yl)thiourea, 1-allyl-3,3-diethyl-2-thiourea, 1-methylallyl-3-methyl-2-thiourea, and N-propene N'-2-hydroxyethylthiourea.

6. The high-temperature and high-humidity resistant OCA optical adhesive according to claim 1, wherein, The mass ratio of the thiourea monomer to the polyurethane acrylate prepolymer is (0.5-3):

1.

7. The high-temperature and high-humidity resistant OCA optical adhesive according to claim 1, wherein, It has at least one of the following characteristics: (1) The glass transition temperature of the soft monomer is -60 to -10℃; (2) The soft monomer includes at least one of ethyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, butyl acrylate and isooctyl acrylate; (3) The hard monomer includes at least one of methyl acrylate, methyl methacrylate, isobornyl acrylate, ethyl methacrylate, styrene and acrylonitrile; (4) The functional monomers include at least one of acrylic acid, acrylamide, N,N-dimethylacrylamide, hydroxyethyl acrylate and hydroxybutyl acrylate; (5) The crosslinking agent includes at least one of diethylene glycol diacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate and trimethylolpropane triacrylate.

8. The preparation method of the high temperature and high humidity resistant OCA optical adhesive according to any one of claims 1 to 7, comprising the following steps: mixing soft monomers, hard monomers, functional monomers, thiourea monomers, polyurethane acrylate prepolymer and photoinitiator evenly, irradiating with ultraviolet light for 3 to 5 minutes, then adding chain transfer agent, tackifying coupling agent, antioxidant, leveling agent and crosslinking agent and mixing evenly, coating and curing with ultraviolet light.

9. The preparation method according to claim 8, wherein, The thickness of the OCA optical adhesive is 50–300 μm.

10. The application of the high-temperature and high-humidity resistant OCA optical adhesive according to any one of claims 1 to 7 or the high-temperature and high-humidity resistant OCA optical adhesive prepared by the preparation method according to any one of claims 8 to 9 in a display screen.

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