Optical adhesive composition, optical adhesive and preparation method and application thereof

Abstract

The application provides an optical adhesive composition, an optical adhesive and a preparation method and application thereof. The optical adhesive composition comprises the following components in parts by mass: 200-350 parts of an acrylate soft monomer; 50-125 parts of an acrylate monomer containing a hydroxyl group; 50-150 parts of an acrylate hard monomer; 15-75 parts of an acrylate monomer containing an epoxy group; 0.15-0.35 parts of an acyl phosphine oxide photoinitiator; 0.25-0.75 parts of an alpha-hydroxy ketone derivative photoinitiator; 0.1-0.4 parts of a cationic photoinitiator; 0.25-0.75 parts of a chain transfer agent; 0.25-1.5 parts of a crosslinking agent; 0-1.5 parts of an antioxidant; 0-1.5 parts of a light stabilizer; and 0-1.5 parts of an ultraviolet absorber. The optical adhesive composition can improve the aging and yellowing of the optical adhesive under light and heat conditions.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to optical adhesive compositions, optical adhesives, their preparation methods and applications. Background Technology

[0002] Display screens serve as the window for human-computer interaction between electronic products and consumers. With continuous updates and upgrades in screen technology and evolving demands, screens in electronic products such as mobile phones, tablets, and smartwatches are evolving from traditional screens towards higher contrast, better clarity, and superior reliability. Among these advancements, optical adhesives, a multifunctional substrate-free polymer bonding material, possess excellent optical transparency, clarity, and good adhesion properties, and are widely used for bonding, encapsulating, and coating optical components.

[0003] Traditional optical adhesives mainly rely on the polymerization of acrylate monomers. The resulting polymers contain a large number of ester bonds (-COO-). When ester bonds are exposed to light and heat for a long time, they are prone to undergo the Norish reaction and decompose into other colored groups, resulting in aging and yellowing. Summary of the Invention

[0004] Therefore, it is necessary to provide an optical adhesive composition, an optical adhesive, a method for preparing the same, and its applications, with the aim of improving the aging and yellowing of optical adhesives under photothermal conditions.

[0005] In one aspect, the present invention provides an optical adhesive composition, wherein the components of the optical adhesive composition, by weight parts, comprise the following components:

[0006] 200-350 parts of soft acrylate monomers, 50-125 parts of hydroxyl-containing acrylate monomers, 50-150 parts of hard acrylate monomers, 15-75 parts of epoxy-containing acrylate monomers, 0.15-0.35 parts of acylphosphide photoinitiator, 0.25-0.75 parts of α-hydroxy ketone derivative photoinitiator, 0.1-0.4 parts of cationic photoinitiator, 0.25-0.75 parts of chain transfer agent, 0.25-1.5 parts of crosslinking agent, 0-1.5 parts of antioxidant, 0-1.5 parts of light stabilizer, 0-1.5 parts of UV absorber;

[0007] Both the acrylate soft monomers and the acrylate hard monomers do not contain hydroxyl or epoxy groups.

[0008] The aforementioned optical adhesive composition primarily comprises acrylate soft monomers, hydroxyl-containing acrylate monomers, and acrylate hard monomers, supplemented with epoxy-containing acrylate monomers. Acylphosphide photoinitiators and α-hydroxy ketone derivative photoinitiators can initiate the polymerization of acrylate monomers to form a polymer network. The acrylate soft monomers, possessing long-chain alkyl groups, enhance polymer flexibility, thereby improving the elasticity and viscosity of the optical adhesive. The acrylate hard monomers constitute the rigid units of the polymer, providing steric hindrance and a rigid structure, thus increasing the cohesive strength and hardness of the optical adhesive. The hydroxyl-containing acrylate monomers introduce hydroxyl functional groups into the polymer, improving the adhesion strength between the polymer and other substrates, thereby enhancing the adhesive strength and chemisorption of the optical adhesive. Furthermore, a cationic photoinitiator initiates the ring-opening polymerization of the epoxy-containing acrylate monomers, forming a polymer with polyether bonds. The relatively stable chemical properties of polyether bonds reduce the probability of oxidative bond breakage or the formation of colored groups under photothermal conditions, thus slowing down the yellowing and aging process of the optical adhesive from the source composition. Chain transfer agents control the molecular weight growth of polymers, acting as molecular weight regulators. Crosslinking agents induce chemical crosslinking reactions between polymer chains, increasing the network density and thus improving cohesive strength, weather resistance, and creep resistance. Antioxidants enhance the high-temperature anti-aging properties of polymers; light stabilizers absorb free radicals generated by photoaging; and UV absorbers absorb low-frequency UV light, reducing photoaging stress. Thus, through the synergistic effect of these specific components and proportions, the aging and yellowing problems of optical adhesives under photothermal conditions are improved.

[0009] In some embodiments, the optical adhesive composition is expressed as a fraction by mass, in parts by mass:

[0010] The acrylate soft monomer is in the form of 250 parts to 325 parts;

[0011] The hydroxyl-containing acrylate monomer is 75 to 100 parts;

[0012] The acrylate hard monomer is 75 to 125 parts;

[0013] The epoxy-containing acrylate monomer is 25 to 50 parts;

[0014] The crosslinking agent is 0.25 parts to 1.5 parts.

[0015] In some embodiments, one or more of the following conditions are met:

[0016] (1) The mass ratio of the epoxy-containing acrylate monomer to the cationic photoinitiator is (100~200):1;

[0017] (2) The mass ratio of the epoxy-containing acrylate monomer to the acrylate soft monomer is (6~13):1.

[0018] In some embodiments, one or more of the following conditions are met:

[0019] (1) The cationic photoinitiator includes one or more of iodonium salts, thionium salts, and ferrocene salts;

[0020] (2) The epoxy-containing acrylate monomers include one or more of glycidyl methacrylate, glycidyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexyl methyl isobutyl acrylate, bisphenol A epoxy acrylate and 3,4-epoxycyclohexyl methacrylate.

[0021] In some embodiments, one or more of the following conditions are met:

[0022] (1) The antioxidants include hindered phenolic antioxidants;

[0023] (2) The light stabilizer includes piperidine derivative light stabilizers;

[0024] (3) The ultraviolet absorber includes oxaloylaniline ultraviolet absorbers.

[0025] In some embodiments, one or more of the following conditions are met:

[0026] (1) The acrylate soft monomers include one or more of the following: n-octyl acrylate, isooctyl acrylate, 2-methyl-2-acrylate-2-butoxyethyl ester, 2-ethylhexyl acrylate, lauryl acrylate and n-octyl methacrylate;

[0027] (2) The hydroxyl-containing acrylate monomers include one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and 4-hydroxybutyl acrylate;

[0028] (3) The acrylate hard monomers include one or more of isobornyl acrylate, isobornyl methacrylate, styrene, and tetrahydrofuran acrylate;

[0029] (4) The acylphosphine oxide photoinitiator includes one or more of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide;

[0030] (5) The α-hydroxy ketone derivative photoinitiator includes one or more of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methylphenylpropanone;

[0031] (6) The chain transfer agent includes one or more of 1-dodecyl mercaptan, tert-dodecyl mercaptan and octadecyl mercaptan;

[0032] (7) The crosslinking agent includes one or more of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate.

[0033] In another aspect, the present invention provides an optical adhesive made from the above-described optical adhesive composition.

[0034] The aforementioned optical adhesive has superior initial transparency, good resistance to high-temperature yellowing, and strong resistance to ultraviolet aging.

[0035] Another aspect of the present invention provides a method for preparing an optical adhesive, comprising the following steps:

[0036] The optical adhesive is prepared by mixing the components of the above-mentioned optical adhesive composition and performing polymerization treatment.

[0037] The above-mentioned method for preparing optical adhesives can produce optical adhesives that are relatively transparent in their initial state, have reliable bonding strength, and exhibit resistance to yellowing and photoaging during long-term use.

[0038] In some embodiments, the acrylate soft monomer, the hydroxyl-containing acrylate monomer, the acrylate hard monomer, the epoxy-containing acrylate monomer, the α-hydroxy ketone derivative photoinitiator, and the chain transfer agent are mixed and subjected to a first photocuring polymerization reaction to obtain a prepolymer;

[0039] The crosslinking agent, the acylphosphide photoinitiator, the cationic photoinitiator, the antioxidant, the light stabilizer, and the ultraviolet absorber are added to the prepolymer to carry out a second photocuring polymerization reaction to obtain the optical adhesive.

[0040] In another aspect, the present invention provides an optical device comprising the optical adhesive described above or an optical adhesive prepared using the preparation method of the optical adhesive composition described above.

[0041] The aforementioned optical devices can maintain high light transmittance and low color shift, reduce the probability of yellowing and darkening, and display content that is more vivid and clear. At the same time, they can maintain good durability under long-term high temperature and strong sunlight radiation. Detailed Implementation

[0042] To facilitate understanding of the present invention, a more complete description will be given below with reference to relevant embodiments. Preferred embodiments of the invention are shown below. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that a thorough and complete understanding of the disclosure of the invention will be achieved.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] One embodiment of this application provides an optical adhesive composition, wherein the components of the optical adhesive composition, by weight parts, include the following components:

[0045] 200-350 parts of soft acrylate monomers, 50-125 parts of hydroxyl-containing acrylate monomers, 50-150 parts of hard acrylate monomers, 15-75 parts of epoxy-containing acrylate monomers, 0.15-0.35 parts of acylphosphide photoinitiator, 0.25-0.75 parts of α-hydroxy ketone derivative photoinitiator, 0.1-0.4 parts of cationic photoinitiator, 0.25-0.75 parts of chain transfer agent, 0.25-1.5 parts of crosslinking agent, 0-1.5 parts of antioxidant, 0-1.5 parts of light stabilizer, and 0-1.5 parts of UV absorber;

[0046] Both soft and hard acrylate monomers do not contain hydroxyl or epoxy groups.

[0047] The aforementioned optical adhesive composition primarily comprises acrylate soft monomers, hydroxyl-containing acrylate monomers, and acrylate hard monomers. Acylphosphide photoinitiators and α-hydroxy ketone derivative photoinitiators initiate the polymerization of acrylate monomers, forming a polymer network. The acrylate soft monomers, possessing long-chain alkyl groups, enhance polymer flexibility, thereby improving the elasticity and viscosity of the optical adhesive. The acrylate hard monomers constitute the rigid units of the polymer, providing steric hindrance and a rigid structure, thus increasing the cohesive strength and hardness of the optical adhesive. The hydroxyl-containing acrylate monomers introduce hydroxyl functional groups into the polymer, improving adhesion strength between the polymer and other substrates, thereby enhancing the adhesive strength and chemisorption of the optical adhesive. The addition of epoxy-containing acrylate monomers, along with the use of cationic photoinitiators, initiates ring-opening polymerization of the epoxy-containing acrylate monomers, forming polymers with polyether bonds. The relatively stable chemical properties of the polyether bonds reduce the probability of oxidative bond breakage or the formation of colored groups under photothermal conditions, thus slowing down the yellowing and aging process of the optical adhesive composition from the source. Chain transfer agents control the molecular weight growth of polymers, acting as molecular weight regulators. Crosslinking agents induce chemical crosslinking reactions between polymer chains, increasing the network density of the polymer and thus improving cohesive strength, weather resistance, and creep resistance. Antioxidants improve the high-temperature anti-aging properties of polymers; light stabilizers absorb free radicals generated by photoaging; and UV absorbers absorb low-frequency UV light, reducing photoaging stress.

[0048] Thus, through the synergistic effect of the specific components and proportions mentioned above, the aging and yellowing problems of optical adhesives under photothermal conditions are improved.

[0049] Understandably, generally speaking, the glass transition temperature of soft acrylate monomers is -10℃ to -70℃; the glass transition temperature of hard acrylate monomers is 70℃ to 130℃.

[0050] As an example, the mass fractions of acrylate soft monomers can be 200 parts, 225 parts, 250 parts, 300 parts, 325 parts, 350 parts, or any two of the above values, for example, 250 parts to 325 parts. The mass fractions of hydroxyl-containing acrylate monomers can be 50 parts, 75 parts, 100 parts, 125 parts, or any two of the above values, for example, 75 parts to 100 parts.

[0051] As an example, the mass fraction of acrylate hard monomers can be 50 parts, 75 parts, 100 parts, 125 parts, 150 parts, or any two of the above values, for example, 75 parts to 125 parts. The mass fraction of epoxy-containing acrylate monomers can be 15 parts, 25 parts, 50 parts, 75 parts, or any two of the above values, for example, 25 parts to 50 parts.

[0052] As an example, the mass fraction of the acylphosphide photoinitiator can be 0.15 parts, 0.25 parts, 0.35 parts, or any two of the above values. The mass fraction of the α-hydroxyketone derivative photoinitiator can be 0.25 parts, 0.5 parts, 0.75 parts, or any two of the above values.

[0053] As an example, the mass fraction of the cationic photoinitiator can be 0.1 parts, 0.25 parts, 0.4 parts, or any two of the above values.

[0054] As an example, the mass fraction of the chain transfer agent can be 0.25 parts, 0.5 parts, 0.75 parts, or any two of the above values.

[0055] As an example, the mass fraction of the crosslinking agent can be 0.25 parts, 0.5 parts, 0.75 parts, 1 part, 1.25 parts, 1.5 parts, or any two of the above values ​​within the range, such as 0.5 parts to 1.25 parts.

[0056] As an example, the mass fraction of the antioxidant can be 0 parts, 0.5 parts, 1 part, 1.5 parts, or any two of the above values.

[0057] As an example, the mass fraction of the light stabilizer can be 0 parts, 0.5 parts, 1 part, 1.25 parts, 1.5 parts, or any two of the above values.

[0058] As an example, the mass fraction of the ultraviolet absorber can be 0 parts, 0.5 parts, 1 part, 1.25 parts, 1.5 parts, or any two of the above values.

[0059] In some embodiments, the optical adhesive composition, by weight parts:

[0060] The composition includes 250-325 parts of soft acrylate monomers, 75-100 parts of hydroxyl-containing acrylate monomers, 75-125 parts of hard acrylate monomers, 25-50 parts of epoxy-containing acrylate monomers, 0.15-0.35 parts of acylphosphide photoinitiator, 0.25-0.75 parts of α-hydroxy ketone derivative photoinitiator, 0.1-0.4 parts of cationic photoinitiator, 0.25-0.75 parts of chain transfer agent, 0.5-1.25 parts of crosslinking agent, 0-1.5 parts of antioxidant, 0-1.5 parts of light stabilizer, and 0-1.5 parts of UV absorber.

[0061] In some embodiments, the mass ratio of the epoxy-containing acrylate monomer to the cationic photoinitiator is (100~200):1. As an example, the mass ratio of the epoxy-containing acrylate monomer to the cationic photoinitiator may be 100:1, 125:1, 150:1, 175:1, 200:1, or any two of the above values.

[0062] In some embodiments, the mass ratio of the epoxy-containing acrylate monomer to the acrylate soft monomer is (6~13):1. As an example, the mass ratio of the epoxy-containing acrylate monomer to the acrylate soft monomer may be 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, or any two of the above values.

[0063] In some embodiments, the cationic photoinitiator includes one or more of iodonium salts, thionium salts, and ferrocene salts.

[0064] In some embodiments, the cationic photoinitiator includes isopropylphenyl ferrocene hexafluoroantimonate.

[0065] In some embodiments, the epoxy-containing acrylate monomers include one or more of glycidyl methacrylate, glycidyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexyl methyl isobutylene acrylate, bisphenol A epoxy acrylate, and 3,4-epoxycyclohexyl methacrylate.

[0066] In some embodiments, the antioxidant includes hindered phenolic antioxidants.

[0067] In some embodiments, the hindered phenolic antioxidant includes one or more of antioxidant 1010 and antioxidant 1076.

[0068] In some embodiments, the light stabilizer includes piperidine derivative light stabilizers.

[0069] In some embodiments, the piperidine derivative light stabilizer includes one or more of light stabilizer 292 and light stabilizer 770.

[0070] In some embodiments, the ultraviolet absorber includes oxaloaniline-based ultraviolet absorbers.

[0071] In some embodiments, the oxaloylaniline-based ultraviolet absorber includes ultraviolet absorber 312.

[0072] In some embodiments, the acrylate soft monomers include one or more of n-octyl acrylate, isooctyl acrylate, 2-methyl-2-acrylate-2-butoxyethyl ester, 2-ethylhexyl acrylate, lauryl acrylate, and n-octyl methacrylate.

[0073] In some embodiments, the hydroxyl-containing acrylate monomers include one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and 4-hydroxybutyl acrylate.

[0074] In some embodiments, the acrylate hard monomers include one or more of isobornyl acrylate, isobornyl methacrylate, styrene, and tetrahydrofuran acrylate.

[0075] In some embodiments, the acylphosphine oxide photoinitiator includes one or more of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0076] In some embodiments, the α-hydroxyketone derivative photoinitiator includes one or more of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methylphenylpropanone.

[0077] In some embodiments, the chain transfer agent includes one or more of 1-dodecyl mercaptan, tert-dodecyl mercaptan, and octadecyl mercaptan.

[0078] In some embodiments, the crosslinking agent includes one or more of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

[0079] Another embodiment of this application provides an optical adhesive made from the optical adhesive composition described above.

[0080] The aforementioned optical adhesive has superior initial transparency, good resistance to high-temperature yellowing, and strong resistance to ultraviolet aging.

[0081] In some of these embodiments, the initial yellowing value of the optical adhesive is <0.3; after 1000h of thermal aging, the yellowing value is <0.6; and after photoaging, the yellowing value is <0.9.

[0082] Another embodiment of this application provides a method for preparing an optical adhesive, comprising the following steps:

[0083] The components of the above-mentioned optical adhesive composition are mixed and polymerized to prepare the optical adhesive.

[0084] The above-mentioned method for preparing optical adhesives can produce optical adhesives that are relatively transparent in their initial state, have reliable bonding strength, and exhibit resistance to yellowing and photoaging during long-term use.

[0085] The optical adhesive described above can be prepared by the above preparation method.

[0086] In some embodiments, acrylate soft monomers, hydroxyl-containing acrylate monomers, acrylate hard monomers, epoxy-containing acrylate monomers, α-hydroxy ketone derivative photoinitiators and chain transfer agents are mixed and subjected to a first photocuring polymerization reaction to obtain a prepolymer.

[0087] A crosslinking agent, an acylphosphide photoinitiator, a cationic photoinitiator, an antioxidant, a light stabilizer, and an ultraviolet absorber are added to the prepolymer to carry out a second photocuring polymerization reaction to obtain an optical adhesive.

[0088] The above-mentioned method for preparing optical adhesive involves two steps of UV curing. The first photocuring polymerization reaction uses an α-hydroxy ketone derivative photoinitiator to construct a prepolymer of appropriate viscosity. The second photocuring polymerization reaction uses a crosslinking agent, an acyl phosphorus oxide photoinitiator, and a cationic photoinitiator to further polymerize the prepolymer, forming an optical adhesive with superior resistance to yellowing, anti-aging properties, and mechanical properties.

[0089] In some embodiments, the viscosity of the prepolymer is 300 cps to 500 cps at 23°C to 27°C. As an example, the viscosity of the prepolymer may be 300 cps, 350 cps, 400 cps, 450 cps, 500 cps, or any two of the above values, for example, 350 cps to 450 cps.

[0090] In some embodiments, the first photocuring polymerization reaction is carried out using a UV lamp.

[0091] In some embodiments, the irradiation power of ultraviolet light in the first photocuring polymerization reaction is 15W~20W.

[0092] In some embodiments, the ultraviolet irradiation dose during the first photocuring polymerization reaction is 50 mJ / cm². 2 ~100mJ / cm 2 .

[0093] In some embodiments, the ultraviolet irradiation band in the first photocuring polymerization reaction is 300nm~420nm.

[0094] In some embodiments, the reaction time of the first photocurable polymerization reaction is 3 min to 7 min.

[0095] In some embodiments, prior to the first photocuring polymerization reaction, the following steps are also included:

[0096] A first mixture is obtained by mixing soft acrylic monomers, hydroxyl-containing acrylate monomers, hard acrylate monomers, epoxy-containing acrylate monomers, α-hydroxy ketone derivative photoinitiators, and chain transfer agents.

[0097] In some embodiments, mixing is performed using a paddle mixer at a speed of 300 rpm to 500 rpm.

[0098] In some embodiments, the temperature of the first mixture during the mixing process is 23°C to 27°C.

[0099] In some embodiments, during the mixing process, nitrogen gas with a purity of 99.9% to 99.999% is introduced into the mixing container at a flow rate of 20 mL / min to 30 mL / min.

[0100] In some embodiments, the following steps are included before the second photocuring polymerization reaction:

[0101] The prepolymer was mixed with a crosslinking agent, an acylphosphide photoinitiator, a cationic photoinitiator, an antioxidant, a light stabilizer, and an ultraviolet absorber, and then degassed to obtain a second mixture.

[0102] In some embodiments, the degassing process includes one or more of vacuum degassing, centrifugal degassing, and ultrasonic degassing.

[0103] In some embodiments, after obtaining the second mixture and before carrying out the second photocuring polymerization reaction, the following steps are also included:

[0104] The second mixture is coated onto a silicone resin-treated insulating liner to obtain an insulating liner / second mixture / insulating liner laminate. The laminate is then subjected to a second photocuring polymerization reaction to obtain an optical adhesive.

[0105] In some embodiments, the ultraviolet irradiation power in the second photocuring polymerization reaction is 18W~40W.

[0106] In some embodiments, the ultraviolet irradiation dose during the second photocuring polymerization reaction is 500 mJ / cm². 2 ~1500mJ / cm 2 .

[0107] In some embodiments, the ultraviolet irradiation band in the second photocuring polymerization reaction is 200nm~500nm.

[0108] In some embodiments, the reaction time of the second photocuring polymerization reaction is 3 to 5 minutes.

[0109] In some embodiments, the insulating liner includes a polyethylene terephthalate insulating liner.

[0110] Another embodiment of this application provides an optical device comprising the optical adhesive described above or an optical adhesive prepared using the preparation method of the optical adhesive composition described above.

[0111] The aforementioned optical devices can maintain high light transmittance and low color shift, reduce the probability of yellowing and darkening, and display content that is more vivid and clear. At the same time, they can maintain good durability under long-term high temperature and strong sunlight radiation.

[0112] In some embodiments, the optical devices include one or more of a display screen, a touch screen, an optical lens group, a car infotainment screen, a dashboard screen, and an outdoor display device.

[0113] The following are specific examples.

[0114] Example 1

[0115] S1. 250g of isooctyl acrylate, 100g of hydroxyethyl acrylate, 125g of isobornyl acrylate, 25g of glyceryl methacrylate, 0.5g of 1-hydroxycyclohexylphenyl ketone, and 0.5g of 1-dodecyl mercaptan were added to a 1000mL three-necked flask equipped with a stirrer, nitrogen inlet, and thermometer. The mixture was stirred at 25°C to obtain the first mixture. The stirrer speed was 300rpm, the nitrogen purity was 99.99%, and the nitrogen flow rate was 20mL / min.

[0116] S2. When nitrogen gas is introduced for 1 hour, the mixture is placed under an 18W ultraviolet lamp for 5 minutes to carry out the first photocuring polymerization reaction. The irradiation wavelength of the ultraviolet lamp is 300nm~420nm, and the irradiation dose is 50mJ / cm. 2 A prepolymer with a viscosity of approximately 400 cps was obtained.

[0117] S3. Add 1g of 1,6-hexanediol diacrylate, 0.25g of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 0.25g of isopropylphenyl ferrocene hexafluoroantimonate, 1.0g of antioxidant 1010, 1.25g of light stabilizer 292, and 1.25g of UV absorber 312 to the prepolymer. After stirring evenly, perform vacuum degassing treatment at -0.9MPa to obtain the second mixture.

[0118] S4. The second mixture is coated onto two 100 μm thick silicone-treated polyethylene terephthalate (PET) release liner layers. The resulting PET liner / second mixture / PET liner laminate is then exposed to ultraviolet radiation with a spectral output of 300 nm–400 nm at a dose of 1000 mJ / cm². 2 An optical adhesive with a layer thickness of 100 micrometers was obtained.

[0119] Example 2

[0120] The preparation method of Example 2 is basically the same as that of Example 1, except that the mass of each component in the optical adhesive composition is not exactly the same, as shown in Table 1.

[0121] Example 3

[0122] The preparation method of Example 3 is basically the same as that of Example 1, except that the mass of each component in the optical adhesive composition is not exactly the same, as shown in Table 1.

[0123] Example 4

[0124] The preparation method of Example 4 is basically the same as that of Example 1, except that the mass of each component in the optical adhesive composition is not exactly the same, as shown in Table 1.

[0125] Example 5

[0126] The preparation method of Example 5 is basically the same as that of Example 1, except that the mass of each component in the optical adhesive composition is not exactly the same, as shown in Table 1.

[0127] Example 6

[0128] The preparation method of Example 6 is basically the same as that of Example 1, except that the mass of each component in the optical adhesive composition is not exactly the same, as shown in Table 1.

[0129] Comparative Example 1

[0130] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that: epoxy-containing acrylate monomers, cationic photoinitiators, antioxidants, light stabilizers and ultraviolet absorbers are omitted, and the mass of other components is not exactly the same, as shown in Table 1.

[0131] Comparative Example 2

[0132] The preparation method of Comparative Example 2 is basically the same as that of Comparative Example 1, except that the mass of each component in the optical adhesive composition is not exactly the same, as shown in Table 1.

[0133] Comparative Example 3

[0134] The preparation method of Comparative Example 3 is basically the same as that of Example 1, except that: epoxy-containing acrylate monomers, cationic photoinitiators, acrylate hard monomers, antioxidants, light stabilizers and ultraviolet absorbers are omitted, the mass of other components is not exactly the same, please refer to Table 1 for details, and laurate acrylate is used as acrylate soft monomer.

[0135] Comparative Example 4

[0136] The preparation method of Comparative Example 4 is basically the same as that of Example 1, except that: epoxy-containing acrylate monomers and acrylate hard monomers are omitted, the mass of other components is not exactly the same, please refer to Table 1 for details, and laurate acrylate is used as acrylate soft monomer.

[0137] Table 1

[0138]

[0139] The optical adhesives prepared in each embodiment and comparative example were subjected to performance tests, including:

[0140] (1) Hardness test of adhesive layer: using a hardness tester DTAAⅡ from Germany, the optical adhesive was cut and stacked to form an adhesive layer with a thickness of 2000 micrometers. The two layers of substrate-free release film were peeled off, the adhesive layer was bonded to the glass plate, and the hardness performance was tested to obtain the Shore hardness.

[0141] (2) Adhesive layer adhesion test: peel off the side of the adhesive layer with the smaller release force, cover it on a non-release PET film, cut it into a sample with a length of 15 cm and a width of 2.5 cm, stick it on a glass plate and let it stand for 20 minutes before testing its adhesion.

[0142] (3) Holding force test: Cut the sample into a 25mm wide strip, remove the light film and attach it horizontally to the bottom of the unperforated edge of the stainless steel plate. Cut it vertically so that the sample size on the stainless steel plate is 25mm×25mm. Remove the heavy film, take another stainless steel plate and attach it to the sample in reverse. Press it with a 2KG roller three times to obtain the sample. Hang a 1KG weight in a 25℃ oven and record the weight's sliding down within 1 hour.

[0143] (4) Spectrophotometric test: one side of the optical adhesive is attached to a 50mm×40mm cover glass plate, and the other side of the optical adhesive is attached to a 50mm×40mm liquid crystal glass plate to form a cover glass / optical adhesive / liquid crystal panel laminate. The laminate is placed in a high temperature (95℃) and a xenon lamp aging chamber for 1000h respectively, and the yellowing value (b) of the laminate is observed.

[0144] The test results are shown in Table 2 below.

[0145] Table 2

[0146]

[0147] From Examples 1-6, Comparative Examples 1-4, and Tables 1-2, it can be seen that Comparative Examples 1 and 2 omitted epoxy-containing acrylate monomers, cationic photoinitiators, antioxidants, light stabilizers, and UV absorbers, resulting in higher initial yellowing values. Furthermore, their yellowing resistance deteriorated under prolonged high heat and long-term light exposure. This indicates that the combination of epoxy-containing acrylate monomers, cationic photoinitiators, antioxidants, light stabilizers, and UV absorbers is crucial for the optical adhesive to exhibit good resistance to photothermal oxidation and yellowing. Comparative Example 3, based on Comparative Examples 1 and 2, omitted the acrylate hard monomers. In the holding force test, the weights fell off, indicating insufficient cohesive strength, poor creep resistance, and poor adhesion of the optical adhesive. Simultaneously, its yellowing resistance was relatively poor, demonstrating the important role of acrylate hard monomers in maintaining certain mechanical properties of the optical adhesive. Even with the addition of antioxidants, light stabilizers, and UV absorbers, Comparative Example 4 still exhibited a yellowing value inferior to the examples, demonstrating that antioxidants, light stabilizers, and UV absorbers alone are insufficient to achieve optimal yellowing resistance. This indicates that epoxy-containing acrylate monomers are crucial for optical adhesives to possess excellent resistance to photothermal oxidation and yellowing.

[0148] The optical adhesives prepared in Examples 1 to 4 have high adhesion and better retention, low initial yellowing value, and low yellowing value under high temperature and light aging, which proves that specific components and ratios are indispensable to achieve long-term yellowing resistance and mechanical reliability of optical adhesives.

[0149] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0150] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An optical adhesive composition, characterized in that, The optical adhesive composition comprises the following components in parts by weight: 200-350 parts of soft acrylate monomers, 50-125 parts of hydroxyl-containing acrylate monomers, 50-150 parts of hard acrylate monomers, 15-75 parts of epoxy-containing acrylate monomers, 0.15-0.35 parts of acylphosphide photoinitiator, 0.25-0.75 parts of α-hydroxy ketone derivative photoinitiator, 0.1-0.4 parts of cationic photoinitiator, 0.25-0.75 parts of chain transfer agent, 0.25-1.5 parts of crosslinking agent, 0-1.5 parts of antioxidant, 0-1.5 parts of light stabilizer, and 0-1.5 parts of UV absorber; Both the acrylate soft monomers and the acrylate hard monomers do not contain hydroxyl or epoxy groups.

2. The optical adhesive composition according to claim 1, characterized in that, In the optical adhesive composition, by mass parts: The acrylate soft monomer is in the form of 250 parts to 325 parts; The hydroxyl-containing acrylate monomer is 75 to 100 parts; The acrylate hard monomer is 75 to 125 parts; The epoxy-containing acrylate monomer is 25 to 50 parts; The crosslinking agent is 0.25 parts to 1.5 parts.

3. The optical adhesive composition according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The mass ratio of the epoxy-containing acrylate monomer to the cationic photoinitiator is (100~200):1; (2) The mass ratio of the epoxy-containing acrylate monomer to the acrylate soft monomer is (6~13):

1.

4. The optical adhesive composition according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The cationic photoinitiator includes one or more of iodonium salts, thionium salts, and ferrocene salts; (2) The epoxy-containing acrylate monomers include one or more of glycidyl methacrylate, glycidyl acrylate, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexyl methyl isobutyl acrylate, bisphenol A epoxy acrylate and 3,4-epoxycyclohexyl methacrylate.

5. The optical adhesive composition as claimed in claim 1, characterized in that, One or more of the following conditions must be met: (1) The antioxidants include hindered phenolic antioxidants; (2) The light stabilizer includes piperidine derivative light stabilizers; (3) The ultraviolet absorber includes oxaloylaniline ultraviolet absorbers.

6. The optical adhesive composition according to any one of claims 1 to 5, characterized in that, One or more of the following conditions must be met: (1) The acrylate soft monomers include one or more of the following: n-octyl acrylate, isooctyl acrylate, 2-methyl-2-acrylate-2-butoxyethyl ester, 2-ethylhexyl acrylate, lauryl acrylate and n-octyl methacrylate; (2) The hydroxyl-containing acrylate monomers include one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate and 4-hydroxybutyl acrylate; (3) The acrylate hard monomers include one or more of isobornyl acrylate, isobornyl methacrylate, styrene, and tetrahydrofuran acrylate; (4) The acylphosphine oxide photoinitiator includes one or more of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; (5) The α-hydroxy ketone derivative photoinitiator includes one or more of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methylphenylpropanone; (6) The chain transfer agent includes one or more of 1-dodecyl mercaptan, tert-dodecyl mercaptan and octadecyl mercaptan; (7) The crosslinking agent includes one or more of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate.

7. An optical adhesive, characterized in that, The optical adhesive is made from the optical adhesive composition as described in any one of claims 1 to 6.

8. A method for preparing an optical adhesive, characterized in that, Includes the following steps: The optical adhesive is prepared by mixing the components of the optical adhesive composition as described in any one of claims 1 to 6 and performing a polymerization process.

9. The method for preparing the optical adhesive as described in claim 8, characterized in that, Includes the following steps: The acrylate soft monomer, the hydroxyl-containing acrylate monomer, the acrylate hard monomer, the epoxy-containing acrylate monomer, the α-hydroxy ketone derivative photoinitiator, and the chain transfer agent are mixed and subjected to a first photocuring polymerization reaction to obtain a prepolymer. The crosslinking agent, the acylphosphide photoinitiator, the cationic photoinitiator, the antioxidant, the light stabilizer, and the ultraviolet absorber are added to the prepolymer to carry out a second photocuring polymerization reaction to obtain the optical adhesive.

10. An optical device, characterized in that, The optical device includes the optical adhesive as described in claim 7 or the optical adhesive prepared by the method of preparing the optical adhesive composition as described in any one of claims 8 to 9.

Images