Ultraviolet curing adhesive composition for bonding optical composite film and preparation method of ultraviolet curing adhesive composition

Abstract

The invention relates to the field of light-cured adhesive materials, in particular to an ultraviolet light-cured adhesive composition for bonding an optical composite film and a preparation method of the ultraviolet light-cured adhesive composition. The ultraviolet curing adhesive composition for bonding the optical composite film is prepared from the following raw materials in parts by weight: 15 to 30 parts of polyurethane acrylate resin, 50 to 90 parts of a UV reactive diluent, 3 to 5 parts of a photoinitiator composition, 0.5 to 2 parts of a defoaming agent, 0.5 to 2 parts of a wetting agent and 0.5 to 2 parts of an adhesion promoter. The ultraviolet curing adhesive for bonding the optical composite film has excellent bonding strength, high transparency, flexibility and aging resistance, interface bonding stability of the optical composite film can be guaranteed, the refractive index of a cured adhesive film is matched with that of a base material, and interface reflection and light loss can be reduced.

Description

Technical Field

[0001] This invention relates to the field of photocurable adhesive materials, and in particular to a UV-curable adhesive composition for bonding optical composite films and its preparation method. Background Technology

[0002] In the fabrication of optical composite films, the UV prism film and the PET substrate need to be bonded together, requiring the use of UV-curable adhesives. In actual production, the UV-curable adhesive must take into account the prism structure of the substrate-UV prism film. The bonding contact area between the UV-curable adhesive and the UV prism film is limited to the top region of the prism microstructure within the UV prism film, resulting in a relatively small bonding area. This leads to lower bonding strength between the UV prism film and the PET substrate, affecting the lifespan and stability of the optical composite film. Furthermore, the refractive index of ordinary UV adhesives is typically between 1.3 and 1.5, which is mismatched with the refractive index of the optical film in the optical composite film, affecting its light transmittance.

[0003] To improve the refractive index of UV adhesives, benzene rings are typically introduced into the molecular chain structure of the UV adhesive to reduce the refractive index difference between the UV adhesive film and the optical PET film, thereby improving the light transmittance of the optical composite film. However, with the increase of benzene ring content in the molecular chain structure of the UV adhesive, the hardness and brittleness of the UV adhesive film increase significantly, leading to deviations in the flexibility and yellowing resistance of the cured UV adhesive film, which cannot meet the requirements for the use of flexible optical composite films. In summary, existing UV-curable adhesives have problems with light transmittance and bonding stability. To address this, the inventors provide a UV-curable adhesive composition for bonding optical composite films and its preparation method. Summary of the Invention

[0004] To address the issues of light transmittance and bonding stability deviations in existing UV-curable adhesives, this invention provides a UV-curable adhesive composition for bonding optical composite films and its preparation method.

[0005] The present invention provides a UV-curable adhesive composition for bonding optical composite films, which is achieved through the following technical solution: An ultraviolet-curable adhesive composition for bonding optical composite films is made from the following raw materials in parts by weight: 15-30 parts polyurethane acrylate resin, 50-90 parts UV-active diluent, 3-5 parts photoinitiator composition, 0.5-2 parts defoamer, 0.5-2 parts wetting agent, and 0.5-2 parts adhesion promoter.

[0006] The UV-curable adhesive for bonding optical composite films in this invention has excellent bonding strength, high transparency, flexibility, and aging resistance, which can ensure the stability of the interface bonding of optical composite films. Moreover, the refractive index of the cured adhesive film matches that of the substrate, which can reduce interface reflection and light loss.

[0007] Preferably, the polyurethane acrylate resin is composed of an aliphatic diisocyanate, a high-refractive-index polyol, a catalyst, and a capping agent; the molar ratio of -NCO in the aliphatic diisocyanate to the molar ratio of -OH in the high-refractive-index polyol is (1.5-2.0):1; the catalyst is at least one of organotin and organobismuth; the sum of the molar amounts of active hydrogen in the capping agent and -OH in the high-refractive-index polyol is equal to 1.0-1.05 times the molar amount of -NCO in the aliphatic diisocyanate.

[0008] Preferably, the capping agent is a compound of a dimercapto compound combined with at least one of hydroxy acrylate, hydroxy methacrylate, N-hydroxymethylacrylamide, and N-hydroxymethylmethacrylamide; the dimercapto compound is at least one of 4-amino-5-pyridine-4H-triazole thiol and 2,5-dimercapto-1,3,4-thiadiazole.

[0009] Introducing sulfur into the molecular chain can effectively increase the refractive index of the UV-cured film.

[0010] Preferably, the aliphatic diisocyanate is at least one selected from isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, norbornene diisocyanate, and methylcyclohexyl diisocyanate.

[0011] The use of aliphatic diisocyanate in this invention ensures the resistance to yellowing of the UV-cured film.

[0012] Preferably, the high-refractive-index polyol is composed of a small-molecule diacid with a molecular weight of 90-200 g / mol, a small-molecule diol with a molecular weight of 66-250 g / mol, a high-refractive-index dihydroxy compound, and a titanate catalyst; the molar ratio of the high-refractive-index dihydroxy compound to the small-molecule diol is 1:(1-3); the ratio of the total molar amount of the high-refractive-index dihydroxy compound and the small-molecule diol to the molar amount of the small-molecule diacid is (1.02-1.10):1.

[0013] Preferably, the high-refractive-index dihydroxy compound is at least one of 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, and di(hydroxyethyl)diselenoether. By introducing sulfur and / or selenium into the molecular chain, the refractive index of the UV-cured film can be effectively increased.

[0014] Preferably, the small molecule diacid is at least one selected from 1,4-cyclohexanedicarboxylic acid, terephthalic acid, phthalic acid, 1,4-succinic acid, glutaric acid, and 1,6-adipic acid; and the small molecule diol is at least one selected from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0015] More preferably, the small molecule diacid comprises a combination of sulfur-containing diacid and sulfur-free diacid; the molar ratio of the sulfur-containing diacid to the sulfur-free diacid is 1:(0.5-2); the sulfur-containing diacid is at least one of mercaptosuccinic acid and 2,3-dimercaptosuccinic acid; the sulfur-free diacid is at least one of 1,4-cyclohexanedicarboxylic acid, terephthalic acid, phthalic acid, 1,4-succinic acid, glutaric acid, and 1,6-adipic acid.

[0016] Preferably, the photoinitiator composition is a compound of at least one of photoinitiator TPO, photoinitiator 819, photoinitiator 651, and photoinitiator 784, combined with photoinitiator 184, photoinitiator 1173, and photoinitiator 2959. At least one of photoinitiator 184, photoinitiator 1173, and photoinitiator 2959 acts as a short-wavelength photoinitiator, which can promote the click chemical reaction of thiols and olefins and improve the physicochemical properties of the film.

[0017] Preferably, the UV-reactive diluent is at least one of butyl methacrylate, N-acryloylmorpholine, isobornyl methacrylate, 2-(tert-butylamino)ethyl methacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, and propoxylated neopentyl glycol diacrylate.

[0018] The present invention provides a method for preparing a UV-curable adhesive composition for bonding optical composite films, which is achieved through the following technical solution: A method for preparing a UV-curable adhesive composition for bonding optical composite films includes the following steps: S1. Preparation of polyurethane acrylate resin; S2. Under light-protected and nitrogen-protected conditions, mixing the polyurethane acrylate resin, UV-active diluent, leveling agent, wetting agent, adhesion promoter, and photoinitiator composition according to the specified ratio, filtering, and discharging to obtain the UV-curable adhesive composition for bonding optical composite films.

[0019] In summary, the present invention has the following advantages: 1. The UV-curable adhesive for bonding optical composite films in this invention has excellent bonding strength, high transparency, flexibility, and aging resistance, which can ensure the stability of the interface bonding of optical composite films. Moreover, the refractive index of the cured adhesive film matches the substrate, which can reduce interface reflection and light loss.

[0020] 2. By introducing sulfur and / or selenium elements into the molecular chain of polyurethane acrylate resin, this invention can effectively increase the refractive index of the UV-cured film. By adjusting the refractive index of the cured film to match the substrate, interface reflection and light loss can be reduced, thereby improving the high light transmittance of the optical composite film.

[0021] 3. The polyurethane acrylate resin in this invention is preferably 2,5-dimercapto-1,3,4-thiadiazole-terminated, and the introduction of a thiadiazole five-membered ring structure into the molecular chain can further improve the refractive index and bonding strength of the film.

[0022] 4. The conjugated double bond structure in 2,5-dimercapto-1,3,4-thiadiazole can undergo the Diels-Alder reaction (DA reaction) under the action of the photoinitiator composition, thereby improving the physicochemical properties and weather resistance of the film. Detailed Implementation

[0023] To further understand the inventiveness and technical advancements of this invention, the preferred embodiments of this invention will be discussed in detail below with reference to examples and comparative examples.

[0024] Example: A UV-curable adhesive composition for bonding optical composite films comprises the following raw materials in parts by weight: 15-30 parts polyurethane acrylate resin, 50-90 parts UV reactive diluent, 3-5 parts photoinitiator composition, 0.5-2 parts defoamer, 0.5-2 parts wetting agent, and 0.5-2 parts adhesion promoter. The wetting agent is a non-silicone wetting and leveling agent, TROYSOL® Z377. The adhesion promoter is an aminosilane such as KH550 or KH792. The defoamer is a non-silicone defoamer, BYK-1788.

[0025] The photoinitiator composition is a combination of a long-wavelength photoinitiator and a short-wavelength photoinitiator. The long-wavelength photoinitiator is at least one selected from photoinitiator TPO, photoinitiator 819, photoinitiator 651, and photoinitiator 784. The short-wavelength photoinitiator is at least one selected from photoinitiator 184, photoinitiator 1173, and photoinitiator 2959. Preferably, the photoinitiator composition is a combination of photoinitiator TPO and photoinitiator 2959.

[0026] The UV reactive diluent is at least one of the following: butyl methacrylate, N-acryloylmorpholine, isobornyl methacrylate, 2-(tert-butylamino)ethyl methacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, dipropylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, and propoxylated neopentyl glycol diacrylate.

[0027] Polyurethane acrylate resin is composed of aliphatic diisocyanate, high refractive index polyol, catalyst, and end-capping agent. The molar ratio of -NCO in aliphatic diisocyanate to -OH in high refractive index polyol is (1.5-2.0):1. The sum of the molar amount of active hydrogen in end-capping agent and -OH in high refractive index polyol is equal to 1.0-1.05 times the molar amount of -NCO in aliphatic diisocyanate.

[0028] The catalyst is at least one of organotin and organobismuth.

[0029] The capping agent is a compound of a dimercapto compound combined with at least one of hydroxy acrylate, hydroxy methacrylate, N-hydroxymethylacrylamide, and N-hydroxymethylmethacrylamide. The dimercapto compound is at least one of 4-amino-5-pyridine-4H-triazole thiol and 2,5-dimercapto-1,3,4-thiadiazole.

[0030] The aliphatic diisocyanate is at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, norbornene diisocyanate, and methylcyclohexyl diisocyanate.

[0031] The high-refractive-index polyol is composed of a small-molecule diacid with a molecular weight of 90-200 g / mol, a small-molecule diol with a molecular weight of 66-250 g / mol, a high-refractive-index dihydroxy compound, and a titanate catalyst. The molar ratio of the high-refractive-index dihydroxy compound to the small-molecule diol is 1:(1-3), and the ratio of the total molar amount of the high-refractive-index dihydroxy compound and the small-molecule diol to the molar amount of the small-molecule diacid is (1.02-1.10):1.

[0032] The high-refractive-index dihydroxy compound is at least one of 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, and di(hydroxyethyl)diselenoether.

[0033] The small molecule diacid is at least one of 1,4-cyclohexanedicarboxylic acid, terephthalic acid, phthalic acid, 1,4-succinic acid, glutaric acid, and 1,6-adipic acid. The small molecule diol is at least one of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0034] To further improve the refractive index of the film, the small molecule diacid is composed of a combination of sulfur-containing diacid and a sulfur-free diacid. The molar ratio of the sulfur-containing diacid to the sulfur-free diacid is 1:(0.5-2). The sulfur-containing diacid is at least one of mercaptosuccinic acid and 2,3-dimercaptosuccinic acid. The sulfur-free diacid is at least one of 1,4-cyclohexanedicarboxylic acid, terephthalic acid, phthalic acid, 1,4-succinic acid, glutaric acid, and 1,6-adipic acid.

[0035] A method for preparing a UV-curable adhesive composition for bonding optical composite films includes the following steps: S1. Preparation of polyurethane acrylate resin; S1.1. Accurately measured small molecule diacid with a molecular weight of 90-200 g / mol, small molecule diol with a molecular weight of 66-250 g / mol, and high refractive index dihydroxy compound are added to the reaction vessel, mixed evenly, and then heated to 120-160℃ for 2-5 h. Subsequently, the temperature is raised to 220-240℃ at a constant rate for 3-6 h. S1.2. Control the temperature at the top of the distillation column to 102±0.5℃. After reacting for 0.5-2.0h, take a sample to measure the acid value of the material in the reactor. When the acid value reaches ≤30mgKOH / g, add 0.1-0.5wt% of titanate catalyst and evacuate the reactor. Gradually reduce the pressure inside the reactor from atmospheric pressure to 10-30Pa within 2-5h. Then take a sample to test the hydroxyl value of the product inside the reactor. When the hydroxyl value of the product inside the reactor is in the range of 74.8-187mgKOH / g, break the vacuum with nitrogen and cool down to 110℃. Then cool down to room temperature with water and the high refractive index polyol can be obtained by discharging the product. S1.3. Take a high-refractive-index polyol with accurate measurement and place it in a reaction vessel. Heat it to 100-130℃ and dehydrate it under vacuum for 1-2 hours. After cooling it to 80-95℃, add aliphatic diisocyanate, catalyst and organic solvent to the reaction vessel under nitrogen protection and mix them evenly. React at 80-95℃ for 1-3 hours. After the reaction is completed, detect the -NCO content of the material in the reaction vessel by the acetone-di-n-butylamine method until the -NCO content in the system reaches the theoretical value. Then the aliphatic diisocyanate-terminated polyurethane prepolymer can be obtained. S1.4. Adjust the temperature of the aliphatic diisocyanate-terminated polyurethane prepolymer in the reactor to 50-65℃, add the end-capping agent and 0.1-0.3wt% of p-hydroxyanisole, maintain the end-capping reaction at 50-65℃ for 30-90 min, then detect the -NCO content of the material in the reactor by the acetone-di-n-butylamine method until the -NCO content in the system is 0, finally remove the organic solvent by vacuum distillation, cool to room temperature, and discharge to obtain polyurethane acrylate resin; S2. Under light-proof and nitrogen protection, the polyurethane acrylate resin, UV-active diluent, leveling agent, wetting agent, adhesion promoter, and photoinitiator composition are mixed evenly according to the formula, filtered, and discharged to obtain the UV-curable adhesive composition for bonding optical composite films.

[0036] Preparation Example 1: The preparation method of polyurethane acrylate resin is as follows: S1, Nitrogen gas is introduced into the reactor, and the air inside the reactor is purged. Under nitrogen protection, 260.88g of 1,4-cyclohexanedicarboxylic acid (molecular weight 172.18, CAS: 1076-97-7, Maclean's) and 76.62g of mercaptosuccinic acid (CAS: 70-49-5, molecular weight 150.153) are added. Adamas (98% purity), 190.74g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, purity 98%, Leyan Reagent), 61.76g of 1,4-butanedithiol (CAS: 1191-08-8, molecular weight 122.252, Maclean, purity 99%), and 4.8g of antioxidant 1010 (CAS: 6683-19-8, Maclean) were added to the reaction vessel, mixed evenly, and then heated to 140℃ and kept at that temperature for 2 hours. Subsequently, the temperature was increased at a constant rate to 230℃ and kept at that temperature for 4 hours. S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, the acid value of the reactants in the reactor was measured. When the acid value of the reactants was ≤30mgKOH / g, 0.32g of tetrabutyl titanate (CAS:5593-70-4, Adamas / Titan) was added and a vacuum was drawn. Within 4 hours, the pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa. Then, the hydroxyl value of the reactants in the reactor was measured. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, the temperature was lowered to room temperature with cold water. The high refractive index polyol was obtained by discharging. The measured hydroxyl value after discharging was 112.1mgKOH / g. S3: Take 160g of high refractive index polyol from S1.2 and place it in a reactor. Heat to 120℃ and dehydrate under vacuum for 2 hours. After breaking the vacuum with nitrogen and cooling to 90℃, add 44.48g of isophorone diisocyanate IPDI (Yantai Wanhua), 0.03g of dibutyltin dilaurate, and 120g of acetone. Mix well and maintain the reaction at 90℃ for 150 minutes. Then, detect the -NCO content of the material in the reactor using the acetone-di-n-butylamine method until the -NCO content in the system reaches the theoretical value to obtain an aliphatic diisocyanate-terminated polyurethane prepolymer. S4. Adjust the temperature of the aliphatic diisocyanate-terminated polyurethane prepolymer in the reactor to 65℃, add 45.04g of hydroxypropyl methacrylate (CAS: 27813-02-1, molecular weight 144.168, Leyan Reagent) and 0.54g of p-hydroxyanisole (CAS: 150-76-5, Wuxi Zhengmao Chemical Co., Ltd.), and maintain the end-capping reaction at 65℃ for 90min. Then, lower the temperature to 10℃ in an ice-water bath, add 19.72g of 4-amino-5-pyridine-4H-triazole thiol (Adamas / Titan, molecular weight 193.23, CAS: 36209-51-5), and maintain the end-capping reaction at 10℃ for 90min. Then, detect the -NCO content of the reactants in the reactor using the acetone-di-n-butylamine method until the -NCO content of the reactants in the reactor is 0. Finally, remove the acetone by vacuum distillation, and discharge the product after cooling to room temperature to obtain polyurethane acrylate resin.

[0037] The difference between Preparation Example 2 and Preparation Example 1 is as follows: S1, nitrogen gas was introduced into the reaction vessel, and the air inside the vessel was purged. Under nitrogen protection, 226.32 g of adipic acid (CAS: 124-04-9, molecular weight 146.14, Aladdin, purity 99.5%) and 76.62 g of mercaptosuccinic acid (CAS: 70-49-5, molecular weight 150.153) were added. Adamas / Titan (98% purity), 190.74g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, purity 98%, Leyan reagent), 61.76g of 1,4-butanedithiol (CAS: 1191-08-8, molecular weight 122.252, Maclean, purity 99%), and 4.8g of antioxidant 1010 were added to the reaction vessel. After mixing evenly, the temperature was raised to 140℃ and kept at that temperature for 2 hours. Then, the temperature was raised to 230℃ at a constant rate over 4 hours and kept at that temperature for 4 hours. S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, a sample was taken to measure the acid value of the reactants in the reactor. When the acid value of the reactants was ≤30mgKOH / g, 0.32g of tetrabutyl titanate was added and a vacuum was drawn. Within 4 hours, the pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa. Then, a sample was taken to measure the hydroxyl value of the product inside the reactor. When the hydroxyl value of the product inside the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, cold water was used to cool it to room temperature. The high refractive index polyol was obtained by discharging. The measured hydroxyl value after discharging was 112.4mgKOH / g.

[0038] The difference between Preparation Example 3 and Preparation Example 1 is as follows: S1, nitrogen gas was introduced into the reaction vessel, and the air inside the vessel was purged. Under nitrogen protection, 260.88 g of 1,4-cyclohexanedicarboxylic acid (molecular weight 172.18, CAS: 1076-97-7, Maclean's) and 76.62 g of mercaptosuccinic acid (CAS: 70-49-5, molecular weight 150.153) were added. Adamas (98% purity), 190.74g of 1,6-hexanediol (CAS: 629-11-8, molecular weight 118.174, purity 98%, Leyan reagent), 61.76g of 1,4-butanedithiol (CAS: 1191-08-8, molecular weight 122.252, Maclean, purity 99.5%), and 4.8g of antioxidant 1010 were added to the reaction vessel. After mixing evenly, the temperature was raised to 140℃ and kept at that temperature for 2 hours. Then, the temperature was raised to 230℃ at a constant rate over 4 hours and kept at that temperature for 4 hours. S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, a sample was taken to measure the acid value of the reactants in the reactor. When the acid value of the reactants was ≤30mgKOH / g, 0.32g of tetrabutyl titanate was added and a vacuum was drawn. Within 4 hours, the pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa. Then, a sample was taken to measure the hydroxyl value of the reactants in the reactor. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, cold water was used to cool the temperature to room temperature. The high refractive index polyol was obtained by discharging the product. The measured hydroxyl value after discharging was 112.6mgKOH / g.

[0039] The difference between Preparation Example 4 and Preparation Example 1 is as follows: S1, nitrogen gas was introduced into the reaction vessel, and the air inside the vessel was purged. Under nitrogen protection, 260.88 g of 1,4-cyclohexanedicarboxylic acid (molecular weight 172.18, CAS: 1076-97-7, Maclean's) and 76.62 g of mercaptosuccinic acid (CAS: 70-49-5, molecular weight 150.153) were added. Adamas (98% purity), 190.74g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, purity 98%, Leyan Reagent), 61.76g of diselenoether (CAS: 51848-10-3, molecular weight 248.04, Yantai Shengkailun Biological Products Co., Ltd.), and 4.8g of antioxidant 1010 were added to the reaction vessel, mixed evenly, and then heated to 140℃ and kept at that temperature for 3 hours. Subsequently, the temperature was increased to 230℃ at a constant rate over 4 hours and kept at that temperature for 4 hours. S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, a sample was taken to measure the acid value of the reactants in the reactor. When the acid value of the reactants was ≤30mgKOH / g, 0.40g of tetrabutyl titanate was added and a vacuum was drawn. Within 4 hours, the pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa. Then, a sample was taken to measure the hydroxyl value of the reactants in the reactor. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, cold water was used to cool the temperature to room temperature. The high refractive index polyol was obtained by discharging the product. The measured hydroxyl value after discharging was 112.6 mgKOH / g.

[0040] The difference between Preparation Example 5 and Preparation Example 1 is as follows: S1, nitrogen gas is introduced into the reaction vessel, and the air inside the vessel is purged. Under nitrogen protection, 260.88 g of 1,4-cyclohexanedicarboxylic acid (molecular weight 172.18, CAS: 1076-97-7, Maclean) and 92.98 g of 2,3-dimercaptosuccinic acid (CAS: 2418-14-6, molecular weight 182.218) are added. 190.74g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, purity 98%, Leyan reagent), 61.76g of 1,4-butanedithiol (CAS: 1191-08-8, molecular weight: 122.252, Maclean, purity 99%), and 4.8g of antioxidant 1010 were added to the reaction vessel, mixed evenly, and then heated to 140℃ and kept at that temperature for 2 hours. Subsequently, the temperature was increased at a constant rate to 230℃ and kept at that temperature for 4 hours. S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, a sample was taken to measure the acid value of the reactants in the reactor. When the acid value of the reactants was ≤30mgKOH / g, 0.32g of tetrabutyl titanate was added and a vacuum was drawn. Within 4 hours, the pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa. Then, a sample was taken to measure the hydroxyl value of the reactants in the reactor. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, cold water was used to cool the temperature to room temperature. The high refractive index polyol was obtained by discharging the product. The measured hydroxyl value after discharging was 112.3 mgKOH / g.

[0041] The difference between Preparation Example 6 and Preparation Example 1 is as follows: S1, nitrogen gas was introduced into the reaction vessel, and the air inside the vessel was purged. Under nitrogen protection, 260.88 g of 1,4-cyclohexanedicarboxylic acid (molecular weight 172.18, CAS: 1076-97-7, Maclean's) and 76.62 g of mercaptosuccinic acid (CAS: 70-49-5, molecular weight 150.153) were added. Adamas / Titan (98% purity), 190.74g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, 98% purity, Leyan Reagent), 24.70g of 1,4-butanedithiol (CAS: 1191-08-8, molecular weight 122.252, Maclean, 99% purity), 75.16g of diselenoether (CAS: 51848-10-3, molecular weight 248.04, Yantai Shengkailun Biological Products Co., Ltd.), and 4.8g of antioxidant 1010 were added to the reaction vessel. After mixing evenly, the temperature was raised to 140℃ and kept at that temperature for 2 hours. Then, the temperature was raised to 230℃ at a constant rate over 4 hours and kept at that temperature for 4 hours. S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, a sample was taken to measure the acid value of the reactants in the reactor. When the acid value of the reactants reached ≤30mgKOH / g, 0.32g of tetrabutyl titanate was added and a vacuum was drawn. Within 4 hours, the pressure inside the reactor was gradually drawn from atmospheric pressure to 1kPa. Then, a sample was taken to measure the hydroxyl value of the reactants in the reactor. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, cold water was used to cool the temperature to room temperature. The high refractive index polyol was obtained by discharging the product. The measured hydroxyl value after discharging was 112.1 mgKOH / g.

[0042] The difference between Preparation Example 7 and Preparation Example 1 is as follows: In S4, the temperature of the aliphatic diisocyanate-terminated polyurethane prepolymer in the reactor was adjusted to 65°C, 45.04 g of hydroxypropyl methacrylate and 0.60 g of p-hydroxyanisole were added, and the end-capping reaction was maintained at 65°C for 90 min. Then, the temperature was lowered to 50°C, and 15.64 g of 2,5-dimercapto-1,3,4-thiadiazole (Siamese reagent, molecular weight 150.246, CAS: 1072-71-5) was added. The end-capping reaction was maintained at 50°C for 45 min. Then, the -NCO content of the reactants in the reactor was detected by the acetone-di-n-butylamine method until the -NCO content of the reactants in the reactor was 0. Finally, the acetone was removed by vacuum distillation, and the product was discharged after cooling to room temperature to obtain polyurethane acrylate resin. The remaining steps were the same.

[0043] The difference between Preparation Example 8 and Preparation Example 1 is as follows: S4, the temperature of the aliphatic diisocyanate-terminated polyurethane prepolymer in the reactor was adjusted to 55°C, 30.96g of N-hydroxymethylacrylamide (CAS: 924-42-5, molecular weight 101.104, Maclean) and 0.5g of p-hydroxyanisole were added, and the end-capping reaction was maintained at 55°C for 60min. Then the temperature was lowered to 50°C, 19.72g of 4-amino-5-pyridine-4H-triazole thiol was added, and the end-capping reaction was maintained at 50°C for 45min. Then the -NCO content of the reactants in the reactor was detected by the acetone-di-n-butylamine method until the -NCO content of the reactants in the reactor was 0. Finally, the acetone was removed by vacuum distillation, and the product was discharged after cooling to room temperature to obtain polyurethane acrylate resin. The remaining steps were the same.

[0044] The difference between Preparation Example 9 and Preparation Example 1 is as follows: S1, nitrogen gas was introduced into the reaction vessel to purge the air inside. Under nitrogen protection, 347.84 g of 1,4-cyclohexanedicarboxylic acid (molecular weight 172.18, CAS: 1076-97-7, Maclean), 250.82 g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, purity 98%, Leyan reagent), and 4.8 g of antioxidant 1010 were added to the reaction vessel. After mixing evenly, the temperature was raised to 140°C and maintained for 2 hours. Subsequently, the temperature was uniformly raised to 230°C and maintained for 4 hours. The reaction was carried out for 4 hours; S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, the acid value of the reactants in the reactor was measured. When the acid value of the reactants was ≤30mgKOH / g, 0.32g of tetrabutyl titanate was added and a vacuum was drawn. The pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa within 4 hours. Then, the hydroxyl value of the reactants in the reactor was measured. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, the temperature was lowered to room temperature with cold water. The polyol was obtained by discharging. The measured hydroxyl value after discharge was 112.0 mgKOH / g. The remaining steps were the same.

[0045] The difference between Preparation Example 10 and Preparation Example 9 is as follows: S4, the temperature of the aliphatic diisocyanate-terminated polyurethane prepolymer in the reactor was adjusted to 65°C, 58.44g of hydroxypropyl methacrylate and 0.54g of p-hydroxyanisole were added, and the end-capping reaction was maintained at 65°C for 90min. Subsequently, the -NCO content of the reactants in the reactor was detected by the acetone-di-n-butylamine method until the -NCO content of the reactants in the reactor was 0. Finally, the acetone was removed by vacuum distillation, and the product was discharged after cooling to room temperature to obtain polyurethane acrylate resin. The remaining steps were the same.

[0046] The difference between Preparation Example 11 and Preparation Example 1 is as follows: S1, nitrogen gas was introduced into the reaction vessel to purge the air inside. Under nitrogen protection, 301.76 g of adipic acid (CAS: 124-04-9, molecular weight 146.14, Aladdin, purity 99.5%), 250.82 g of 3-methyl-1,5-pentanediol (CAS: 4457-71-0, molecular weight 118.174, purity 98%, Leyan reagent), and 4.8 g of antioxidant 1010 were added to the reaction vessel. After mixing evenly, the temperature was raised to 140°C and maintained for 2 hours. Subsequently, the temperature was uniformly increased to 230°C over 4 hours. The reaction was carried out at ℃ for 4 hours; S2, the temperature at the top of the distillation column was controlled between 102±0.5℃. After 1 hour of reaction, the acid value of the reactants in the reactor was measured. When the acid value of the reactants was ≤30mgKOH / g, 0.32g of tetrabutyl titanate was added and a vacuum was drawn. The pressure inside the reactor was gradually drawn from atmospheric pressure to 30Pa within 4 hours. Then, the hydroxyl value of the reactants in the reactor was measured. When the hydroxyl value of the reactants in the reactor was in the range of 110-114mgKOH / g, the reaction was stopped. The vacuum was broken with nitrogen to restore atmospheric pressure and the temperature was lowered to 110℃. Then, the temperature was lowered to room temperature with cold water. The polyol was discharged, and the measured hydroxyl value was 112.3 mgKOH / g. The remaining steps were the same.

[0047] The difference between Preparation Example 12 and Preparation Example 11 is as follows: S4, the temperature of the aliphatic diisocyanate-terminated polyurethane prepolymer in the reactor was adjusted to 65°C, 58.44g of hydroxypropyl methacrylate and 0.54g of p-hydroxyanisole were added, and the end-capping reaction was maintained at 65°C for 90min. Subsequently, the -NCO content of the reactants in the reactor was detected by the acetone-di-n-butylamine method until the -NCO content of the reactants in the reactor was 0. Finally, the acetone was removed by vacuum distillation, and the product was discharged after cooling to room temperature to obtain polyurethane acrylate resin. The remaining steps were the same.

[0048] Example 1: A UV-curable adhesive composition for bonding optical composite films is made from the following raw materials in parts by weight: 15 parts of the polyurethane acrylate resin in Preparation Example 1, 4 parts of N-acryloylmorpholine (CAS: 5117-12-4, Maclean), 13 parts of butyl methacrylate (CAS: 97-88-1, Shanghai Ke-Ether Chemical Technology Co., Ltd.), 30 parts of isobornyl methacrylate (CAS: 7534-94-3, TCI (Shanghai) Chemical Industry Development Co., Ltd.), 20 parts of propoxylated neopentyl glycol diacrylate (CAS: 84170-74-1, Shanghai Mairui Biochemical Technology Co., Ltd.), 3 parts of photoinitiator TPO (Aladdin, CAS: 75980-60-8), 1 part of photoinitiator 2959 (CAS: 106797-53-9, Aladdin), 1.2 parts of defoamer BYK-1788 (BYK Chemicals), and 0.8 parts of non-silicone wetting and leveling agent TROYSOL®. Z377 (Nanjing Chuhai New Materials Technology Co., Ltd.), 1 sample of KH792 (Leyan Reagent, CAS: 1760-24-3).

[0049] A method for preparing a UV-curable adhesive composition for bonding optical composite films includes the following steps: S1. For the preparation of polyurethane acrylate resin, see Preparation Example 1; S2. Under light-protected and nitrogen-protected conditions, 15 parts of the polyurethane acrylate resin from Preparation Example 1, 4 parts of N-acryloylmorpholine, 13 parts of butyl methacrylate, 30 parts of isobornyl methacrylate, 20 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792 were added to a reaction vessel and mixed evenly. The mixture was then filtered and discharged to obtain a UV-curable adhesive composition for bonding optical composite films.

[0050] The difference between Example 2 and Example 1 is that: an ultraviolet curable adhesive composition for bonding optical composite films is made from 20 parts of polyurethane acrylate resin (as in Example 1), 6 parts of N-acryloylmorpholine, 18 parts of butyl methacrylate, 25 parts of isobornyl methacrylate, 15 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792.

[0051] The difference between Example 3 and Example 1 is that: an ultraviolet curable adhesive composition for bonding optical composite films is made from 25 parts of polyurethane acrylate resin (as in Example 1), 8 parts of N-acryloylmorpholine, 23 parts of butyl methacrylate, 20 parts of isobornyl methacrylate, 10 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792.

[0052] The difference between Example 4 and Example 1 is that: an ultraviolet curable adhesive composition for bonding optical composite films is made from 30 parts of polyurethane acrylate resin (as in Example 1), 10 parts of N-acryloylmorpholine, 28 parts of butyl methacrylate, 15 parts of isobornyl methacrylate, 5 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792.

[0053] The difference between Example 5 and Example 1 is that: an ultraviolet curable adhesive composition for bonding optical composite films is made from 22 parts of polyurethane acrylate resin from Preparation Example 1, 7 parts of N-acryloylmorpholine, 20 parts of butyl methacrylate, 23 parts of isobornyl methacrylate, 13 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792.

[0054] The difference between Example 6 and Example 5 is that 22 parts of polyurethane acrylate resin in Preparation Example 1 are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 2 in the UV-curable adhesive composition for bonding optical composite films, while the other components remain unchanged.

[0055] The difference between Example 7 and Example 5 is that 22 parts of polyurethane acrylate resin in Preparation Example 1 are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 3 in the UV-curable adhesive composition for bonding optical composite films, while the other components remain unchanged.

[0056] The difference between Example 8 and Example 5 is that the 22 parts of polyurethane acrylate resin in Preparation Example 1 in the UV-curable adhesive composition for bonding optical composite films are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 4, while the other components remain unchanged.

[0057] The difference between Example 9 and Example 5 is that 22 parts of polyurethane acrylate resin in Preparation Example 1 are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 5 in the UV-curable adhesive composition for bonding optical composite films, while the other components remain unchanged.

[0058] The difference between Example 10 and Example 5 is that 22 parts of polyurethane acrylate resin in Preparation Example 1 are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 6 in the UV-curable adhesive composition for bonding optical composite films, while the other components remain unchanged.

[0059] The difference between Example 11 and Example 5 is that 22 parts of polyurethane acrylate resin in Preparation Example 1 are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 7 in the UV-curable adhesive composition for bonding optical composite films, while the other components remain unchanged.

[0060] The difference between Example 12 and Example 5 is that 22 parts of polyurethane acrylate resin in Preparation Example 1 are replaced with 22 parts of polyurethane acrylate resin in Preparation Example 8 in the UV-curable adhesive composition for bonding optical composite films, while the other components remain unchanged.

[0061] The difference between Comparative Example 1 and Example 1 is that the UV-curable adhesive composition for bonding optical composite films is made of 15 parts of aliphatic polyurethane diacrylate oligomer CR92784 (Guangdong Haohui New Material Co., Ltd.), 17 parts of butyl methacrylate, 25 parts of isobornyl methacrylate, 15 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792.

[0062] The difference between Comparative Example 2 and Example 1 is that the UV-curable adhesive composition for bonding optical composite films is made of 15 parts of difunctional aliphatic polyurethane acrylate SD 6304 (Guangdong Songda New Materials Co., Ltd.), 17 parts of butyl methacrylate, 25 parts of isoborneol methacrylate, 15 parts of propoxylated neopentyl glycol diacrylate, 3 parts of photoinitiator TPO, 1 part of photoinitiator 2959, 1.2 parts of defoamer BYK-1788, 0.8 parts of non-silicone wetting and leveling agent TROYSOL® Z377, and 1 part of KH792.

[0063] The difference between Comparative Example 3 and Example 1 is that 15 parts of polyurethane acrylate resin in Preparation Example 1 were replaced with 15 parts of polyurethane acrylate resin in Preparation Example 9 in the UV-curable adhesive composition for bonding optical composite films, while the other components remained unchanged.

[0064] The difference between Comparative Example 4 and Example 1 is that 15 parts of polyurethane acrylate resin in Preparation Example 1 were replaced with 15 parts of polyurethane acrylate resin in Preparation Example 10 in the UV-curable adhesive composition for bonding optical composite films, while the other components remained unchanged.

[0065] The difference between Comparative Example 5 and Example 1 is that 15 parts of polyurethane acrylate resin in Preparation Example 1 were replaced with 15 parts of polyurethane acrylate resin in Preparation Example 11 in the UV-curable adhesive composition for bonding optical composite films, while the other components remained unchanged.

[0066] The difference between Comparative Example 6 and Example 1 is that 15 parts of polyurethane acrylate resin in Preparation Example 1 were replaced with 15 parts of polyurethane acrylate resin in Preparation Example 12 in the UV-curable adhesive composition for bonding optical composite films, while the other components remained unchanged.

[0067] Test sample preparation: The UV-curable adhesive composition for bonding optical composite films was coated onto a PET base film (TOYOBOA optical grade polyester film A4360, thickness 0.125 mm, size 50 mm) using a UV coating device. The surface was coated with a medium-pressure mercury lamp (40mW / cm²) for 5 seconds to form an adhesive film. This film was then laminated with a UV prism adhesive film on a tension roller. Subsequently, it was cured with a high-pressure mercury lamp (40mW / cm²) for 10 seconds, with a total light exposure time of 15 seconds. After the UV-cured adhesive was fully cured, the test sample was obtained. The dry adhesive film thickness in the test sample was 8±0.5μm.

[0068] Performance Test 1: The refractive index and light transmittance of the test sample were measured using a YH1100 transmittance and haze meter (measuring range 400~700nm) from Guangdong Yuelian Instrument Co., Ltd. Performance Test 2: The flexibility of the coating film was measured using a QTX film flexibility tester according to GB / T 1731-2020 standard. The diameter of the shaft rod represents the flexibility value of the coating at this point. Performance Test 3: The peel force between the test sample film and the UV prism film was measured according to the 180° peel test method in ISO 29862-2024. After aging the test sample in a 60℃ / 90%RH constant temperature and humidity chamber for 1000h, it was removed and allowed to warm for 2h before the peel force between the film and the UV prism film after 1000h at 60℃ / 90%RH was measured.

[0069] Table 1: Performance test parameters of UV-curable adhesive compositions for bonding optical composite films in Examples 1-12 and Comparative Examples 1-6

[0070] Note: The refractive index of optical grade polyester film A4360 was measured to be 1.634 using a WYA-2W Abbe refractometer.

[0071] As can be seen from Example 1 and Comparative Examples 1-2 and Table 1, the UV-curable adhesive for bonding optical composite films in this invention has excellent bonding strength, high transparency, flexibility, and aging resistance.

[0072] Based on Examples 1 and 2-4 and Table 1, it can be seen that although the flexibility decreases (1.5→2.5mm) with the increase of polyurethane acrylate resin content, the peel strength between the adhesive film and the UV prism adhesive film is significantly improved. By precisely controlling the content of polyurethane acrylate resin, the prepared adhesive film can match the refractive index of optical PET film and optical PC film, thus ensuring the stability of the interfacial bonding of the optical composite film while matching the refractive index of the adhesive film with the substrate. This reduces interfacial reflection and light loss, while also ensuring the overall high light transmittance of the optical composite film.

[0073] Based on Examples 1, Comparative Examples 3-4, and Comparative Examples 5-6, and referring to Table 1, it can be seen that the optical composite film prepared using the UV-curable adhesive in Example 1 has better light transmittance, and the refractive index of the film formed by the UV-curable adhesive in Example 1 matches better with the refractive index of the PET film. Furthermore, the polyurethane acrylate resin synthesized by end-capping with 4-amino-5-pyridine-4H-triazole thiol and hydroxypropyl methacrylate (molar ratio 1 / 3) can impart better refractive index, bonding strength, and anti-aging properties to the film formed by the UV-curable adhesive for bonding the optical composite film.

[0074] Based on Examples 1-4 and Example 5, and in conjunction with Table 1, it can be seen that the optical composite film prepared using Example 5 as the UC adhesive has better high light transmittance. The refractive index of the adhesive film formed by the UV-curable adhesive in Example 5 matches better with the refractive index of the general optical grade polyester film A4360.

[0075] Combining Examples 5 and 6 with Table 1, it can be seen that, in terms of the light transmittance of the optical composite film synthesized by replacing adipic acid with 1,4-cyclohexanedicarboxylic acid, the optical composite film prepared in Example 5 has better light transmittance. In Example 5, the molecular chain of the film contains cyclohexyl groups, which improves the refractive index of the film. The refractive index of the film matches that of the substrate, which can reduce interface reflection and light loss.

[0076] Combining Examples 5 and 7 with Table 1, it can be seen that when 1,6-hexanediol is replaced with 3-methyl-1,5-pentanediol to synthesize polyurethane acrylate resin, the optical composite film prepared in Example 6 has better light transmittance in terms of optical composite film transmittance. The presence of methyl groups in the side chains of 3-methyl-1,5-pentanediol gives the film better flexibility and light transmittance, and improves the cohesive strength of the film, which can improve the peel strength.

[0077] Combining Examples 5, 8, and 10 with Table 1, it can be seen that when bis(hydroxyethyl)diselenoether is replaced with 1,4-butanedithiol to synthesize polyurethane acrylate resin, the optical composite film prepared in Example 8 exhibits better light transmittance and aging resistance. This is because introducing -Se-Se- into the molecular chain structure is more effective than introducing sulfur in increasing the refractive index of the film. The refractive index of the film obtained in Example 8 matches better with that of the PET substrate. However, bis(hydroxyethyl)diselenoether is expensive and has a monopolistic distribution channel, making it more suitable for meeting customers' personalized customization needs for high-refractive-index films.

[0078] Combining Examples 5 and 9 with Table 1, it can be seen that when 2,3-dimercaptosuccinic acid is used to replace mercaptosuccinic acid in the synthesis of polyurethane acrylate resin, the side chain of the molecular chain changes from one thiol group to two thiol groups, resulting in an increase in the crosslinking density of the film and a decrease in the flexibility of the film. The sulfur content in Example 9 is higher than that in Example 5, and the refractive index of the film obtained in Example 9 matches the refractive index of the PET substrate better. The light transmittance of the optical composite film prepared in Example 9 is relatively...

[0079] Combining Examples 5 and 11 with Table 1, it can be seen that replacing 4-amino-5-pyridine-4H-triazole thiol with 2,5-dimercapto-1,3,4-thiadiazole to synthesize polyurethane acrylate resin, with methyl allyl and two thiol end groups, increases the crosslinking density of the film, thereby reducing its flexibility. In Example 11, the sulfur content is higher than that in Example 5, and the refractive index of Example 11 is also higher than that of Example 5, and it matches the refractive index of the PET substrate better. Therefore, the optical composite film prepared in Example 11 has better light transmittance and aging resistance.

[0080] Combining Examples 5 and 12 with Table 1, it can be seen that the polyurethane acrylate resin synthesized by replacing hydroxypropyl methacrylate with N-hydroxymethylacrylamide contains -NH (secondary amine group) in the main chain of the polyurethane acrylate resin, which can form more hydrogen bonds, improve the molecular chain aggregation, and thus give the film and UV prism film better heat resistance, weather resistance and bonding strength.

[0081] It should be noted that this specific embodiment is merely an explanation of the technical solution of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A UV-curable adhesive composition for bonding optical composite films, characterized in that: The product is made from the following raw materials in parts by weight: 15-30 parts polyurethane acrylate resin, 50-90 parts UV reactive diluent, 3-5 parts photoinitiator composition, 0.5-2 parts defoamer, 0.5-2 parts wetting agent, and 0.5-2 parts adhesion promoter; the polyurethane acrylate resin is made from aliphatic diisocyanate, high refractive index polyol, catalyst, and end-capping agent; the molar ratio of -NCO in the aliphatic diisocyanate to the molar ratio of -OH in the high refractive index polyol is (1.5-2.0):1; the catalyst is at least one of organotin and organobismuth; the sum of the molar amounts of active hydrogen in the end-capping agent and -OH in the high refractive index polyol is equal to 1.0-1.05 times the molar amount of -NCO in the aliphatic diisocyanate.

2. The UV-curable adhesive composition for bonding optical composite films according to claim 1, characterized in that: The capping agent is a compound of a dimercapto compound combined with at least one of hydroxy acrylate, hydroxy methacrylate, N-hydroxymethylacrylamide, and N-hydroxymethylmethacrylamide; the dimercapto compound is at least one of 4-amino-5-pyridine-4H-triazole thiol and 2,5-dimercapto-1,3,4-thiadiazole.

3. The UV-curable adhesive composition for bonding optical composite films according to claim 1, characterized in that: The aliphatic diisocyanate is at least one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, norbornene diisocyanate, and methylcyclohexyl diisocyanate.

4. The UV-curable adhesive composition for bonding optical composite films according to claim 1, characterized in that: The high-refractive-index polyol is composed of a small-molecule diacid with a molecular weight of 90-200 g / mol, a small-molecule diol with a molecular weight of 66-250 g / mol, a high-refractive-index dihydroxy compound, and a titanate catalyst; the molar ratio of the high-refractive-index dihydroxy compound to the small-molecule diol is 1:(1-3); the ratio of the total molar amount of the high-refractive-index dihydroxy compound and the small-molecule diol to the molar amount of the small-molecule diacid is (1.02-1.10):

1.

5. The UV-curable adhesive composition for bonding optical composite films according to claim 4, characterized in that: The high-refractive-index dihydroxy compound is at least one of 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, and di(hydroxyethyl)diselenoether.

6. The UV-curable adhesive composition for bonding optical composite films according to claim 5, characterized in that: The small molecule diacid is at least one selected from 1,4-cyclohexanedicarboxylic acid, terephthalic acid, phthalic acid, 1,4-succinic acid, glutaric acid, and 1,6-adipic acid; the small molecule diol is at least one selected from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

7. The UV-curable adhesive composition for bonding optical composite films according to claim 4, characterized in that: The small molecule diacid comprises a combination of sulfur-containing diacid and sulfur-free diacid; the molar ratio of the sulfur-containing diacid to the sulfur-free diacid is 1:(0.5-2); the sulfur-containing diacid is at least one of mercaptosuccinic acid and 2,3-dimercaptosuccinic acid; the sulfur-free diacid is at least one of 1,4-cyclohexanedicarboxylic acid, terephthalic acid, phthalic acid, 1,4-succinic acid, glutaric acid, and 1,6-adipic acid.

8. The UV-curable adhesive composition for bonding optical composite films according to claim 1, characterized in that: The photoinitiator composition is a compound of at least one of photoinitiator TPO, photoinitiator 819, photoinitiator 651, photoinitiator 784, photoinitiator 184, photoinitiator 1173, and photoinitiator 2959; the UV-active diluent is at least one of butyl methacrylate, N-acryloylmorpholine, isobornyl methacrylate, 2-(tert-butylamino)ethyl methacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, dipropylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, and propoxylated neopentyl glycol diacrylate.

9. A method for preparing a UV-curable adhesive composition for bonding optical composite films according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Preparation of polyurethane acrylate resin; S2. Under light-proof and nitrogen protection, the polyurethane acrylate resin, UV-active diluent, leveling agent, wetting agent, adhesion promoter, and photoinitiator composition are mixed evenly according to the formula, filtered, and discharged to obtain the UV-curable adhesive composition for bonding optical composite films.

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