OCA and SCA combined optical adhesive with light equalizing effect and preparation method of OCA and SCA combined optical adhesive

Abstract

The invention discloses an OCA and SCA combined optical adhesive with a light equalizing effect and a preparation method thereof, and belongs to the technical field of optical adhesives. The optical cement is compounded with the OCA layer, the SCA layer and the AG film through physical lamination to form a three-layer structure; the OCA layer is prepared by copolymerizing a hydroxyl-containing monomer, a soft monomer and the like, realizing a semi-transparent black effect by adopting a carbon black component and carrying out UV prepolymerization, mixed coating and hot air drying; the SCA layer is prepared by taking EVA resin as a base material, adding a peroxide cross-linking agent, a silane coupling agent, a prepolymerization initiator, an inorganic passivator and a light equalizing material, and performing ultrasonic dispersion, melt blending and calendering film forming; and finally, interlayer tight combination is achieved through hot-pressing compounding and UV curing, and the light uniformizing effect is further optimized through the AG film. Compared with the prior art, various composite structures are adopted, the light uniformizing material is added into the optical cement, the light uniformizing effect on a high-brightness light source is achieved, and the optical cement has the characteristics of high yellowing stability, damp-heat aging resistance and anti-dazzle performance and is suitable for high-end display screen fitting scenes.

Description

Technical Field

[0001] This invention relates to the field of optical adhesive technology, and in particular to an optical adhesive combining OCA and SCA that has a light-averaging effect and its preparation method. Background Technology

[0002] As display technology evolves towards higher definition, larger size, and greater flexibility, optical adhesives, as the core bonding material for display modules, directly impact display quality and reliability. Currently, mainstream optical adhesives are mainly divided into two categories: OCA (Optically Transparent Adhesive) and SCA (Solid Optical Adhesive). OCA adhesives are primarily based on acrylates, possessing high light transmittance, low haze, and excellent bonding properties, making them widely used in touchscreen bonding. SCA adhesives are mostly based on EVA resin systems, achieving bonding through hot pressing or UV curing, exhibiting good step filling and aging resistance, making them suitable for complex display structures.

[0003] In the prior art, Chinese Patent Publication No. CN114196353A discloses a high-filler SCA optical adhesive, which improves flowability by controlling the VA content and MI value of EVA resin and adding microcrystalline wax, achieving a step coverage rate of up to 50% and solving the bubble problem; Chinese Patent Publication No. CN116333653A discloses an automotive OCA optical adhesive, which optimizes high temperature and high humidity resistance by compounding hard and soft acrylic monomers and light stabilizers, achieving stable adhesion to automotive display materials. However, the above patents are all single OCA or SCA systems and do not involve a physical bonding design of OCA and SCA.

[0004] Currently, there are no optical adhesive products in the industry that combine OCA and SCA into a two-layer structure through physical lamination. Traditional single-layer optical adhesives have performance bottlenecks. While OCA adhesives have excellent light transmittance, they lack aging resistance and step filling ability; SCA adhesives have good filling ability, but their bonding strength and light transmittance are lower than OCA. In addition, existing combined optical adhesives mostly use chemical blending modification, resulting in poor interlayer compatibility, easy delamination or performance degradation, and difficulty in simultaneously meeting the comprehensive requirements of high light transmittance, high adhesion, aging resistance, and uniform light effect.

[0005] The physical bonding optical adhesives of OCA and SCA also have the following technical problems in practical applications. First, the aging resistance is insufficient. EVA resin is easily degraded by water and oxygen. A single OCA or SCA layer cannot simultaneously meet the requirements of resistance to damp heat, UV, and high and low temperature alternation, resulting in the degradation of optical performance. Second, the optical uniformity is poor. Inorganic additives (such as passivators and light-diffusing materials) are prone to agglomeration and formation of scattering centers during the composite process. In addition, the difference in OCA and SCA layer thickness and curing shrinkage rate can easily cause optical distortion, affecting the stability of yellowing and the light-diffusing effect. Furthermore, relying on single hot pressing or UV curing makes it difficult to achieve tight interlayer bonding and performance synergy, and it is impossible to take into account high adhesion, aging resistance, and anti-glare properties.

[0006] Therefore, developing a physical combination optical adhesive for OCA and SCA that synergistically leverages the performance advantages of both has become a pressing technical problem to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention aims to provide a combined OCA and SCA optical adhesive with uniform light distribution and its preparation method, thereby achieving excellent aging resistance and yellowing stability while simultaneously ensuring uniform light distribution and adhesion performance.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing a combined OCA and SCA optical adhesive with light-averaging effect is as follows: Step 1, Preparation of OCA optical adhesive: Hydroxyl monomer, alkyl monomer, N-vinylpyrrolidone, soft monomer and prepolymerization initiator are mixed and oxygen is removed under nitrogen atmosphere; carbon black powder is added for high-speed dispersion, and then irradiated with ultraviolet light to obtain prepolymer; then prepolymerization initiator, crosslinking agent, silane coupling agent and antioxidant are added, mixed evenly and coated on PET release film, and dried with hot air to obtain OCA optical adhesive; Step 2, Preparation of SCA optical adhesive: EVA resin, peroxide crosslinking agent, silane coupling agent and prepolymerization initiator are mixed evenly; inorganic passivating agent is added, and after ultrasonic dispersion and melt blending, homogenizing material is added and mixed evenly; finally, the mixture is extruded, filtered and calendered into a film to obtain SCA optical adhesive. Step 3, Preparation of OCA and SCA combined optical adhesive: The SCA optical adhesive and the OCA optical adhesive are bonded together and hot-pressed to form a double-layer structure; then the untreated surface of the AG film is rolled and bonded to the OCA adhesive surface to form a three-layer structure; finally, the composite structure is UV cured to obtain the OCA and SCA combined optical adhesive with uniform light effect. Step 2 can also be performed as follows: Silane coupling agent and anhydrous ethanol are added to the inorganic passivating agent, ultrasonically dispersed, and then ground to obtain a nano-scale dispersion. After spray drying, a pretreated passivating agent is obtained for later use. EVA resin, peroxide crosslinking agent, silane coupling agent, and prepolymerization initiator are mixed evenly. The pretreated passivating agent is added, and after ultrasonic dispersion and melt blending, a homogenizing material is added and mixed evenly. Finally, the mixture is extruded, filtered, and calendered into a film to obtain SCA optical adhesive.

[0009] Preferably, the preparation method of the OCA and SCA combined optical adhesive with the light-averaging effect is as follows, in parts by weight: Step 1: Preparation of OCA optical adhesive: Add 20-30 parts of hydroxyl-containing monomer, 0.2-0.6 parts of alkyl monomer, 15-25 parts of N-vinylpyrrolidone, 50-60 parts of soft monomer and 0.02-0.06 parts of prepolymerization initiator to the reaction vessel. Under stirring, purge with nitrogen for 10-30 minutes to remove oxygen from the system. Then add 0.1-0.3 parts of carbon black powder and disperse at high speed of 1200-1800 rpm for 20-40 minutes. Irradiate the mixture with ultraviolet light for 3-8 minutes to obtain a prepolymer. Continue to add 0.04-0.08 parts of prepolymerization initiator, 0.1-0.3 parts of crosslinking agent, 0.1-0.3 parts of silane coupling agent and 0.1-0.5 parts of antioxidant. After mixing evenly, coat the mixture onto a PET release film with a coating thickness of 20-200 μm and dry with hot air at 50-70℃ for 2-8 minutes to obtain OCA optical adhesive. Step 2, Preparation of SCA optical adhesive: First, mix 90-96 parts of EVA resin, 0.8-1.5 parts of peroxide crosslinking agent, 1-2 parts of silane coupling agent, and 0.4-0.8 parts of prepolymerization initiator evenly; add 0.5-1 parts of inorganic passivating agent, and use ultrasonic dispersion and twin-screw melt blending, with ultrasonic power of 500-1000W and time of 5-15 minutes; twin-screw temperature of 120-140℃ and screw speed of 100-500rpm; then add 1.5-3 parts of homogenizing material and mix evenly; then, use conventional extrusion process to transport and filter the mixture through the melt pump at the end of the extruder, and calender it into a film to obtain an SCA optical adhesive with a thickness of 40-200μm. Step 3: Preparation of the OCA and SCA combined optical adhesive: SCA optical adhesive is bonded to OCA optical adhesive (with release film removed) via hot-pressing at 60-80℃, 0.3-0.5MPa, and 1-3m / min to form a double-layer structure of SCA and OCA. The AG film is then bonded to the OCA adhesive layer with the AG-treated side facing up and the untreated side facing up at room temperature, 0.2-0.5MPa, and 1-3m / min via roller pressing to form a three-layer optical adhesive structure. The composite three-layer structure is then subjected to UV post-curing at a wavelength of 365nm or 395nm and an energy of 300-500mJ / cm². 2 An optical adhesive combining OCA and SCA with uniform light distribution was prepared.

[0010] A further preferred embodiment is the preparation method of the OCA and SCA combined optical adhesive with uniform light distribution effect, as follows, in parts by weight: Step 1: Preparation of OCA optical adhesive: Add 20-30 parts of hydroxyl-containing monomer, 0.2-0.6 parts of alkyl monomer, 15-25 parts of N-vinylpyrrolidone, 50-60 parts of soft monomer and 0.02-0.06 parts of prepolymerization initiator to the reaction vessel. Under stirring, purge with nitrogen for 10-30 minutes to remove oxygen from the system. Then add 0.1-0.3 parts of carbon black powder and disperse at high speed of 1200-1800 rpm for 20-40 minutes. Irradiate the mixture with ultraviolet light for 3-8 minutes to obtain a prepolymer. Continue to add 0.04-0.08 parts of prepolymerization initiator, 0.1-0.3 parts of crosslinking agent, 0.1-0.3 parts of silane coupling agent and 0.1-0.5 parts of antioxidant. After mixing evenly, coat the mixture onto a PET release film with a coating thickness of 20-200 μm and dry with hot air at 50-70℃ for 2-8 minutes to obtain OCA optical adhesive. Step 2, Preparation of SCA optical adhesive: Add 0.05-0.2 parts of silane coupling agent and 3-8 parts of anhydrous ethanol to 0.5-1 parts of inorganic passivating agent, ultrasonically disperse for 20-40 minutes at 400-800W, then grind using a sand mill with 0.2-0.4mm zirconia beads as the grinding media at 1500-3000rpm for 1-3 hours to obtain a nano-scale dispersion. Spray dry to obtain a pretreated passivating agent for later use; first, add 90-96 parts of EVA resin, 0.8-1.5 parts of peroxide crosslinking agent, and 1- Mix 2 parts of silane coupling agent and 0.4-0.8 parts of prepolymerization initiator evenly; add 0.5-1 parts of pretreatment passivating agent, and use ultrasonic dispersion and twin-screw melt blending, with ultrasonic power of 500-1000W and time of 5-15 minutes; twin-screw temperature of 120-140℃ and screw speed of 100-500rpm; then add 1.5-3 parts of homogenizing material and mix evenly; then use conventional extrusion process to convey and filter the mixture through the melt pump at the end of the extruder, and calender it into a film to obtain SCA optical adhesive with a thickness of 40-200μm. Step 3: Preparation of the OCA and SCA combined optical adhesive: SCA optical adhesive is bonded to OCA optical adhesive (with release film removed) via hot-pressing at 60-80℃, 0.3-0.5MPa, and 1-3m / min to form a double-layer structure of SCA and OCA. The AG film is then bonded to the OCA adhesive layer with the AG-treated side facing up and the untreated side facing up at room temperature, 0.2-0.5MPa, and 1-3m / min via roller pressing to form a three-layer optical adhesive structure. The composite three-layer structure is then subjected to UV post-curing at a wavelength of 365nm or 395nm and an energy of 300-500mJ / cm². 2 An optical adhesive combining OCA and SCA with uniform light distribution was prepared.

[0011] The hydroxyl-containing monomer is at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and hydroxyethyl methacrylate.

[0012] The alkyl monomer is at least one selected from dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, dimethylaminoethyl acrylamide, and N,N-dimethylaminopropyl acrylamide.

[0013] The soft monomer is at least one of butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isobutyl acrylate.

[0014] The prepolymerization initiator is at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2,2-dimethoxy-2-phenylacetophenone.

[0015] The crosslinking agent is at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, and pentaerythritol triacrylate.

[0016] The silane coupling agent is at least one of γ-epoxypropoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and aminopropyltriethoxysilane.

[0017] The antioxidant is at least one of antioxidant 264, antioxidant 1076, antioxidant 1010, and antioxidant 168.

[0018] The peroxide crosslinking agent is at least one of tert-butyl peroxide-2-ethylhexanoate, dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide.

[0019] The light-diffusing material is at least one of microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, nano-silica, PMMA microspheres, PS microspheres, and titanium dioxide.

[0020] The inorganic passivating agent is at least one of layered bimetallic hydroxide, ZnO nanorods, and nano-montmorillonite.

[0021] Preferably, the inorganic passivating agent is a combination of layered bimetallic hydroxide and ZnO nanorods in a mass ratio of 4-6:2-5.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects: 1) This invention extends the water and oxygen permeation path by adding layered bimetallic hydroxides and utilizing their layered barrier structure. At the same time, combined with the free radical scavenging ability of ZnO nanorods, it effectively delays the degradation of EVA resin and improves the resistance of optical adhesive to humid heat aging.

[0023] 2) This invention uses silane coupling agent to pretreat inorganic passivating agent and then uses ultrasonic dispersion and grinding processes to improve its dispersibility in EVA matrix and reduce agglomeration defects; making the SCA layer more uniformly cured, the crosslinking network more dense, and optimizing yellowing stability and uniform light effect.

[0024] 3) This invention designs a double-layer composite structure of OCA and SCA, which is combined with AG film to form a three-layer functional system. Through hot pressing and UV curing processes, the layers are tightly bonded, which synergistically leverages the high adhesion of OCA, the aging resistance of SCA and the anti-glare properties of AG film to improve overall optical performance and reliability. Detailed Implementation

[0025] Some material parameters and their sources: Carbon black powder, model: PRINTEX35, particle size: 31nm, brand: ORION.

[0026] EVA resin, model: EVA2005 series, brand: ExxonMobil.

[0027] Nano silica, model: AEROSIL®R972, particle size: 16nm, brand: Evonik.

[0028] Microcrystalline wax, model: 3971, brand: Sasol, South Africa.

[0029] Layered bimetallic hydroxide, molecular formula: [Mg4Al2(OH)] 16 CO3·4H2O, MgO / Al2O3 molar ratio 3:1, specific surface area BET(m 2 / g): 158, bulk density (g / mL): 0.38.

[0030] ZnO nanorods, chemical composition: ZnO, crystal form: hexagonal wurtzite, purity ≥99.5wt%, morphology: nanorods, size: diameter: 30-80nm, length: 200-800nm, aspect ratio (L / D): 5-15, specific surface area (BET): 15-35m² 2 / g.

[0031] Nano-montmorillonite, interlayer spacing: 1.20-1.30 nm, layer thickness (single layer): 1 nm, lateral dimension of layer: 100-500 nm, specific surface area (BET): 50-90 m² 2 / g.

[0032] The AG film is a PET-based anti-glare hardened film with a total thickness of 100-125μm, a 60° gloss of 10-20GU, a haze of 10-20%, a total light transmittance of ≥88%, and a surface pencil hardness of ≥3H.

[0033] All other raw materials used in the embodiments and comparative examples of this invention are commercially available products.

[0034] Example 1 A method for preparing a combined OCA and SCA optical adhesive with a light-averaging effect is as follows, in parts by weight: Step 1: Preparation of OCA optical adhesive: Add 25 parts of 2-hydroxypropyl acrylate, 0.4 parts of dimethylaminoethyl methacrylate, 20 parts of N-vinylpyrrolidone, 55 parts of 2-ethylhexyl acrylate, and 0.04 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone to a reaction vessel. Purge with nitrogen for 20 minutes under stirring to remove oxygen from the system. Then add 0.2 parts of carbon black powder and disperse at 1500 rpm for 30 minutes. Irradiate the mixture with ultraviolet light for 5 minutes to obtain a prepolymer. Continue adding 0.06 parts of 2,2-dimethoxy-2-phenylacetophenone, 0.2 parts of tripropylene glycol diacrylate, 0.2 parts of γ-methacryloyloxypropyltrimethoxysilane, and 0.3 parts of antioxidant 1076. After mixing evenly, coat the mixture onto a 75 μm PET release film with a coating thickness of 30 μm. Dry with hot air at 60℃ for 5 minutes to obtain the OCA optical adhesive. Step 2, Preparation of SCA optical adhesive: First, mix 94 parts of EVA resin, 1.2 parts of dicumyl peroxide, 1.5 parts of γ-methacryloyloxypropyltrimethoxysilane, and 0.6 parts of 1-hydroxycyclohexylphenyl ketone evenly; add 0.8 parts of inorganic passivating agent, and use ultrasonic dispersion and twin-screw melt blending, with ultrasonic power of 800W and time of 10 minutes; twin-screw temperature of 130℃ and screw speed of 300rpm; then add 0.8 parts of nano silica and 1.5 parts of microcrystalline wax, and mix evenly; then, use conventional extrusion process to transport and filter the mixture through the melt pump at the end of the extruder, and calender it into a film to obtain an SCA optical adhesive with a thickness of 50μm. Step 3: Preparation of the OCA and SCA combined optical adhesive: SCA optical adhesive is bonded to OCA optical adhesive (with release film removed) via hot-pressing at 70℃, 0.4MPa, and 1.5m / min to form a double-layer structure of SCA and OCA. The AG film, with its AG-treated side facing up and the untreated side bonded to the OCA adhesive layer at room temperature, 0.3MPa, and 1.5m / min, is then rolled to form a three-layer optical adhesive structure. The composite three-layer structure is then subjected to UV post-curing at 365nm wavelength and 400mJ / cm² energy. 2 An optical adhesive combining OCA and SCA with uniform light distribution was prepared.

[0035] The inorganic passivating agent is a layered bimetallic hydroxide.

[0036] This invention addresses the vulnerability of EVA resin to moisture erosion, which can lead to performance degradation. It explores the introduction of a single inorganic passivating agent to improve stability. This embodiment selects a layered bimetallic hydroxide because its layered structure extends the moisture penetration path, and its surface hydroxyl groups are more compatible with EVA resin, reducing interfacial defects. Simultaneously, nano-silica is added, utilizing its scattering and guiding effect on ultraviolet light to ensure more uniform curing of the SCA layer and a denser cross-linked network, thereby reducing the impact of uncured component migration.

[0037] Example 2 The preparation method of a combined OCA and SCA optical adhesive with uniform light effect is basically the same as that in Example 1, except that the inorganic passivating agent is ZnO nanorods.

[0038] Example 3 The preparation method of a combined OCA and SCA optical adhesive with uniform light effect is basically the same as that in Example 1, except that the inorganic passivating agent is nano-montmorillonite.

[0039] Example 4 The preparation method of an optical adhesive combining OCA and SCA with uniform light effect is basically the same as that in Example 1, except that the inorganic passivating agent is composed of layered bimetallic hydroxide and ZnO nanorods in a mass ratio of 5:3.

[0040] Building upon the single passivating agent, further consideration is given to how to enhance the anti-aging effect through functional complementarity. Layered bimetallic hydroxides excel at physical barrier properties, while ZnO nanorods can capture free radicals generated during degradation. The combination of the two can form a dual protection of physical barrier and chemical inhibition. The design focuses on the ratio of the two components; a 5:3 mass ratio allows the layered structure to fully exert its barrier effect while the ZnO nanorods promptly scavenge free radicals, avoiding potential gaps in protection that might arise from relying solely on physical barriers, thus more comprehensively delaying material aging.

[0041] Example 5 The preparation method of an optical adhesive combining OCA and SCA with uniform light effect is basically the same as that in Example 1, except that the inorganic passivating agent is composed of layered bimetallic hydroxide and nano-montmorillonite in a mass ratio of 5:3.

[0042] Example 6 A method for preparing a combined OCA and SCA optical adhesive with a light-averaging effect is as follows, in parts by weight: Step 1: Preparation of OCA optical adhesive: Add 25 parts of 2-hydroxypropyl acrylate, 0.4 parts of dimethylaminoethyl methacrylate, 20 parts of N-vinylpyrrolidone, 55 parts of 2-ethylhexyl acrylate, and 0.04 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone to a reaction vessel. Purge with nitrogen for 20 minutes under stirring to remove oxygen from the system. Then add 0.2 parts of carbon black powder and disperse at 1500 rpm for 30 minutes. Irradiate the mixture with ultraviolet light for 5 minutes to obtain a prepolymer. Continue adding 0.06 parts of 2,2-dimethoxy-2-phenylacetophenone, 0.2 parts of tripropylene glycol diacrylate, 0.2 parts of γ-methacryloyloxypropyltrimethoxysilane, and 0.3 parts of antioxidant 1076. After mixing evenly, coat the mixture onto a 75 μm PET release film with a coating thickness of 30 μm. Dry with hot air at 60℃ for 5 minutes to obtain the OCA optical adhesive. Step 2, Preparation of SCA optical adhesive: Add 0.1 parts γ-methacryloxypropyltrimethoxysilane and 5 parts anhydrous ethanol to 0.8 parts inorganic passivating agent, ultrasonically disperse for 30 minutes at 600W, then grind using a sand mill with 0.3mm zirconia beads as the grinding medium at 2000rpm for 2 hours to obtain a nano-scale dispersion. After spray drying, obtain a pretreated passivating agent for later use; first, add 94 parts EVA resin, 1.2 parts dicumyl peroxide, and 1.4 parts γ-methacryloxypropyltrimethoxysilane... Propyltrimethoxysilane and 0.6 parts of 1-hydroxycyclohexylphenyl ketone were mixed evenly; 0.8 parts of pretreatment passivating agent were added, and the mixture was ultrasonically dispersed and melt-blended using a twin-screw extruder with an ultrasonic power of 800W for 10 minutes and a twin-screw temperature of 130℃ and a screw speed of 300rpm; then 0.8 parts of nano-silica and 1.5 parts of microcrystalline wax were added and mixed evenly; the mixture was then extruded using a conventional extrusion process, conveyed by a melt pump at the end of the extruder, filtered, and calendered into a film to obtain a 50μm thick SCA optical adhesive. Step 3: Preparation of the OCA and SCA combined optical adhesive: SCA optical adhesive is bonded to OCA optical adhesive (with release film removed) via hot-pressing at 70℃, 0.4MPa, and 1.5m / min to form a double-layer structure of SCA and OCA. The AG film, with its AG-treated side facing up and the untreated side bonded to the OCA adhesive layer at room temperature, 0.3MPa, and 1.5m / min, is then rolled to form a three-layer optical adhesive structure. The composite three-layer structure is then subjected to UV post-curing at 365nm wavelength and 400mJ / cm² energy. 2 An optical adhesive combining OCA and SCA with uniform light distribution was prepared.

[0043] The inorganic passivating agent is composed of layered bimetallic hydroxide and ZnO nanorods in a mass ratio of 5:3.

[0044] To address the issue of inorganic passivating agents easily agglomerating and affecting dispersibility, this embodiment introduces a silane coupling agent pretreatment process. By modifying the surface of the passivating agent with a silane coupling agent, its compatibility with the EVA matrix is ​​improved. Combined with ultrasonic dispersion and grinding, the passivating agent is further formulated into a nanoscale dispersion, reducing optical defects caused by agglomeration. The pretreated passivating agent, combined with optimized UV curing parameters, results in a more uniform distribution of the SCA optical adhesive and more thorough deep curing, ultimately improving aging resistance and further delaying the yellowing and aging of the adhesive.

[0045] Comparative Example 1 The preparation method of an optical adhesive combining OCA and SCA with uniform light effect is basically the same as that in Example 1, except that the inorganic passivating agent is not added.

[0046] Comparative Example 2 The preparation method of an optical adhesive combining OCA and SCA with uniform light effect is basically the same as that in Example 1, except that the nano-silica is not added.

[0047] Test Example 1 Damp heat aging test: The OCA and SCA combined optical adhesives prepared in Examples 1-6 and Comparative Examples 1-2 were cut into 50mm×50mm samples. After removing the release film, they were bonded to a 1mm thick clean glass substrate and placed in a constant temperature and humidity chamber. The temperature was set at 85℃ and the relative humidity at 85%, and the samples were aged continuously for 1000 hours.

[0048] The haze was measured before aging (H0) and after aging (H1) using a haze meter. The haze change rate after aging was calculated as ΔH = (H1 – H0) / H0 × 100%.

[0049] For water vapor transmission rate testing, the OCA and SCA combined optical adhesives prepared in Examples 1-6 and Comparative Examples 1-2 were cut into 50mm × 50mm samples and placed in the chamber of a MOCON water vapor transmission rate tester for testing. Test conditions: temperature 38℃, humidity 100%. Water vapor transmission rate (g / m³) was measured. 2 ·day).

[0050] Each group was tested three times, and the average value was taken. The test results are shown in Table 1.

[0051] Table 1

[0052] Test Example 2 Yellowing Index Test: Sample preparation: The OCA and SCA combined optical adhesives prepared in Examples 1-6 and Comparative Examples 1-2 were applied to a clean, impurity-free 1mm thick soda-lime glass slide, ensuring that no air bubbles remained.

[0053] Testing instrument: A spectrophotometer (model: Konica Minolta CM-3600A) was used, set to CIE Lab color space mode.

[0054] Test steps: Yellowing index YI0 of the sample under initial test conditions: Place the glass slide with adhesive film in the test chamber, and use the glass slide of the same batch without adhesive film as the reference background to test and record the yellowing index value.

[0055] Yellowing index test after aging: Place the glass slide with adhesive film in a constant temperature and humidity chamber, set the temperature to 85℃ and the relative humidity to 85%, and continue aging for 1000 hours; after taking it out, place it in a normal temperature and humidity environment for 24 hours, and then test the yellowing index YI1 after aging according to the above method.

[0056] Calculate the yellowing index change rate ΔYI=(YI1–YI0) / YI0×100%.

[0057] Parallel experiments: Each group of samples was tested three times, and the average value was taken. The relevant test data are summarized in Table 2.

[0058] Table 2

[0059] In Comparative Example 1, because no inorganic passivating agent was added, the EVA resin in the SCA layer was easily degraded by water, oxygen, and ultraviolet light. After the molecular chains broke, micropores and chromophores were generated, resulting in a haze change rate as high as 165.9% and a water vapor transmission rate of 2.30 g / m². 2 •day, the yellowing index change rate was as high as 275.0%; in Comparative Example 2, without the addition of nano silica, the SCA layer curing uniformity was insufficient, the cross-linking network had defects, and water and oxygen were more likely to penetrate and cause resin degradation, with a yellowing index change rate of 190.9%.

[0060] Examples 1-3, by adding a single inorganic passivating agent, effectively delayed water and oxygen permeation and resin free radical degradation by utilizing the layered barrier structure of layered bimetallic hydroxide, the free radical scavenging ability of ZnO nanorods, or the layered effect of nano-montmorillonite, reducing the yellowing index change rate to 75.0%-81.8%. Example 4 used a combination of layered bimetallic hydroxide and ZnO nanorods, achieving synergistic protection through physical barrier against water and oxygen permeation and chemical free radical scavenging, significantly reducing the yellowing index change rate. Example 5 used a combination of two physical barrier passivating agents, with overlapping functions but no synergy, resulting in a yellowing inhibition effect close to that of a single passivating agent. Example 6, based on the combination system of Example 4, improved the dispersibility of the passivating agent through silane coupling agent pretreatment, reducing the particle size. The silane coupling agent also improved the interfacial compatibility between the particles and the EVA matrix. On the one hand, the nanoscale dispersion strengthened water vapor barrier, further reducing the haze change rate; on the other hand, it strengthened the density of the cross-linked network, resulting in the optimal yellowing inhibition effect.

Claims

1. A method for preparing an optical adhesive having a uniform light effect OCA and SCA combined optical adhesive, characterized in that, The method is as follows: Step 1, preparation of OCA optical glue: the hydroxyl-containing monomer, alkyl monomer, N-vinyl pyrrolidone, soft monomer and prepolymerization initiator are mixed, and oxygen is excluded under a nitrogen atmosphere; carbon black powder is added for high-speed dispersion, and then a prepolymer is prepared by ultraviolet irradiation; then the prepolymerization initiator, crosslinking agent, silane coupling agent and antioxidant are added, mixed uniformly, coated on the PET release film, dried by hot air, and the OCA optical glue is prepared; Step 2, preparation of SCA optical glue: the EVA resin, peroxide crosslinking agent, silane coupling agent and prepolymerization initiator are mixed uniformly; the inorganic passivation agent is added, ultrasonic dispersion and melt blending are carried out, then the homogenizing material is added and mixed uniformly; finally, the mixture is filtered by extrusion, calendaring into a film, and the SCA optical glue is prepared; Step 3, preparation of OCA and SCA combined optical glue: the SCA optical glue is combined with the OCA optical glue, and a double-layer structure is formed by hot pressing; The non-treated surface of the AG film is roll-bonded with the OCA layer, forming a three-layer structure; finally, the composite structure is UV cured, and the OCA and SCA combined optical glue with homogenizing effect is obtained; The step 2 can also use the following method: the silane coupling agent and anhydrous ethanol are added to the inorganic passivation agent, ultrasonic dispersion is carried out, then grinding is carried out to obtain a nanoscale dispersion liquid, which is spray dried to obtain a pretreated passivation agent for standby use; the EVA resin, peroxide crosslinking agent, silane coupling agent and prepolymerization initiator are mixed uniformly; the pretreated passivation agent is added, ultrasonic dispersion and melt blending are carried out, then the homogenizing material is added and mixed uniformly; finally, the mixture is filtered by extrusion, calendaring into a film, and the SCA optical glue is prepared.

2. The method of claim 1, wherein the preparation method of the OCA and SCA combined optical adhesive with uniform light effect is characterized in that, The method is as follows, and the weight parts are as follows: Step 1, preparation of OCA optical glue: 20-30 parts of hydroxyl-containing monomer, 0.2-0.6 parts of alkyl monomer, 15-25 parts of N-vinyl pyrrolidone, 50-60 parts of soft monomer and 0.02-0.06 parts of prepolymerization initiator are put into a reaction kettle, and nitrogen is introduced for 10-30 minutes under stirring conditions to exclude oxygen in the system; then 0.1-0.3 parts of carbon black powder is added, and high-speed dispersion is carried out at 1200-1800 rpm for 20-40 minutes; the mixture is irradiated by ultraviolet light for 3-8 minutes, a prepolymer is prepared, and 0.04-0.08 parts of prepolymerization initiator, 0.1-0.3 parts of crosslinking agent, 0.1-0.3 parts of silane coupling agent and 0.1-0.5 parts of antioxidant are continuously added, mixed uniformly, coated on the PET release film, and dried by hot air at 50-70°C for 2-8 minutes, and the OCA optical glue is obtained; Step 2, preparation of SCA optical adhesive: 90-96 parts of EVA resin, 0.8-1.5 parts of peroxide crosslinking agent, 1-2 parts of silane coupling agent and 0.4-0.8 parts of prepolymerization initiator are mixed uniformly; 0.5-1 parts of inorganic passivation agent is added, ultrasonic dispersion and double screw melt blending are adopted, ultrasonic power is 500-1000 W, time is 5-15 minutes; double screw temperature is 120-140℃, screw rotation speed is 100-500 rpm; 1.5-3 parts of isotropic material is added, mixed uniformly; then the mixed material is transported by melt pump at the end of the extruder, filtered and calendered into a film to obtain SCA optical adhesive with a thickness of 40-200 μm; Step 3, preparation of OCA and SCA combined optical adhesive: the SCA optical adhesive is attached to the OCA optical adhesive without release film, and a double-layer structure of SCA and OCA is formed by hot pressing, at a temperature of 60-80℃, a pressure of 0.3-0.5 MPa, and a speed of 1-3 m / min; the AG treatment surface of the AG film is upward, and the non-treatment surface is attached to the OCA layer at room temperature, a pressure of 0.2-0.5 MPa, and a speed of 1-3 m / min by roller pressing, to finally form a three-layer structure optical adhesive; the three-layer structure after compounding is subjected to UV post-curing treatment at a wavelength of 365 nm or 395 nm and an energy of 300-500 mJ / cm 2 , to obtain an OCA and SCA combined optical adhesive with uniform light effect.

3. The method of claim 1, wherein the preparation method of the optical adhesive having uniform light effect OCA and SCA combined type is characterized by, The method is as follows, in parts by weight: Step 1, preparation of OCA optical adhesive: 20-30 parts of hydroxyl-containing monomer, 0.2-0.6 parts of alkyl monomer, 15-25 parts of N-vinyl pyrrolidone, 50-60 parts of soft monomer and 0.02-0.06 parts of prepolymerization initiator are put into a reaction kettle, nitrogen is introduced for 10-30 minutes under stirring condition to exclude oxygen in the system; then 0.1-0.3 parts of carbon black powder is added, high-speed dispersion is carried out at 1200-1800 rpm for 20-40 minutes, the mixture is irradiated by ultraviolet light for 3-8 minutes, a prepolymer is prepared, 0.04-0.08 parts of prepolymerization initiator, 0.1-0.3 parts of crosslinking agent, 0.1-0.3 parts of silane coupling agent and 0.1-0.5 parts of antioxidant are continuously added, mixed uniformly, coated on a PET release film, the coating thickness is 20-200 μm, hot air drying is carried out at 50-70℃ for 2-8 minutes, and OCA optical adhesive is obtained; Step 2, preparation of SCA optical adhesive: 0.05-0.2 parts of silane coupling agent and 3-8 parts of anhydrous ethanol are added in 0.5-1 parts of inorganic passivation agent, ultrasonic dispersion is carried out for 20-40 minutes, power is 400-800 W, then grinding is carried out by a sand mill, grinding medium is 0.2-0.4 mm zirconia bead, rotation speed is 1500-3000 rpm, time is 1-3 hours, a nanoscale dispersion liquid is obtained, a pretreated passivation agent is obtained by spray drying for standby use; 90-96 parts of EVA resin, 0.8-1.5 parts of peroxide crosslinking agent, 1-2 parts of silane coupling agent and 0.4-0.8 parts of prepolymerization initiator are mixed uniformly; 0.5-1 parts of pretreated passivation agent is added, ultrasonic dispersion and double screw melt blending are adopted, ultrasonic power is 500-1000 W, time is 5-15 minutes; double screw temperature is 120-140℃, screw rotation speed is 100-500 rpm; 1.5-3 parts of isotropic material is added, mixed uniformly; then the mixed material is transported by melt pump at the end of the extruder, filtered and calendered into a film to obtain SCA optical adhesive with a thickness of 40-200 μm; Step 3, preparation of OCA and SCA combined optical adhesive: the SCA optical adhesive is attached to the OCA optical adhesive without release film, and a double-layer structure of SCA and OCA is formed by hot pressing, at a temperature of 60-80℃, a pressure of 0.3-0.5 MPa, and a speed of 1-3 m / min; the AG treatment surface of the AG film is upward, and the non-treatment surface is attached to the OCA layer at room temperature, a pressure of 0.2-0.5 MPa, and a speed of 1-3 m / min by roller pressing, to finally form a three-layer structure optical adhesive; the three-layer structure after compounding is subjected to UV post-curing treatment at a wavelength of 365 nm or 395 nm and an energy of 300-500 mJ / cm 2 , to obtain an OCA and SCA combined optical adhesive with uniform light effect.

4. The method of claim 1-3, wherein the preparation method of the OCA and SCA combined optical adhesive with uniform light effect is characterized in that, The hydroxyl-containing monomer is at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, hydroxyethyl methacrylate; the alkyl monomer is at least one of dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, dimethylaminoethyl acrylamide, N,N-dimethylaminopropyl acrylamide; the soft monomer is at least one of butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isobutyl acrylate.

5. The method of claim 1-3, wherein the preparation method of the uniform light effect OCA and SCA combined optical adhesive is characterized in that, The prepolymerization initiator is at least one of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,2-dimethoxy-2-phenylphenylacetophenone; the crosslinking agent is at least one of 1,6-hexanediol diacrylate, tripropyleneglycol diacrylate, pentaerythritol triacrylate.

6. The method of claim 1-3, wherein the preparation method of the uniform light effect OCA and SCA combined optical adhesive is characterized in that, The silane coupling agent is at least one of gamma-glycidoxypropyltrimethoxysilane, gamma-methacryloyloxypropyltrimethoxysilane, aminopropyltriethoxysilane; the antioxidant is at least one of antioxidant 264, antioxidant 1076, antioxidant 1010, antioxidant 168.

7. The method of claim 1-3, wherein the preparation method of the uniform light effect OCA and SCA combined optical adhesive is characterized in that, The peroxide crosslinking agent is at least one of tert-butyl peroxy-2-ethylhexanoate, dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide; the isotropic material is at least one of microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, nano-silicon dioxide, PMMA microspheres, PS microspheres, titanium dioxide.

8. The method of claim 1-3, wherein the preparation method of the uniform light effect OCA and SCA combined optical adhesive is characterized in that, The inorganic passivator is at least one of layered double hydroxide, ZnO nanorod, nanomontmorillonite.

9. The method of claim 1-3, wherein the preparation method of the uniform light effect OCA and SCA combined optical adhesive is characterized in that, The inorganic passivator is a combination of layered double hydroxide and ZnO nanorod in a mass ratio of 4-6:2-5.

10. An optical adhesive having uniform light effect (OCA) and SCA combined, characterized in that, Prepared by the preparation method of any one of claims 1-9.

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