UV composite adhesive and preparation method thereof

Abstract

The invention relates to the technical field of UV composite adhesive processing, in particular to a UV composite adhesive and a preparation method thereof. The water-based adhesive is prepared from the following raw materials in parts by weight: 30-40 parts of an epoxy modified acrylate prepolymer, 15-25 parts of a polyurethane acrylate polymer, 10-20 parts of a multifunctional acrylate monomer, 4-6 parts of an organic silicon modified acrylate prepolymer, 2-4 parts of a photoinitiator and 1-2 parts of an adhesion promoter. The UV composite adhesive prepared according to the formula has good flexibility, bending resistance and durability and can bear large deformation without cracks in the use process of a flexible electronic device, and the reliability of the device in repeated folding and curling operation is remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of UV composite adhesive processing, and more specifically, to a UV composite adhesive and a preparation method thereof. Background Art

[0002] Flexible electronics is an emerging electronics technology that fabricates electronic devices made of organic or inorganic materials on flexible or stretchable substrates. Compared to traditional rigid electronic devices, flexible electronics possess properties such as bendability, stretchability, and foldability. They maintain stable electronic performance under various operating environments and deformation conditions, and are therefore suitable for foldable and rollable devices.

[0003] In the fabrication of flexible electronic devices, UV adhesives are an important bonding material, widely used to secure organic and inorganic electronic devices to flexible substrates. Currently, conventional UV adhesives are commonly used in the industry, typically curing with ultraviolet light to achieve rapid bonding.

[0004] However, while existing UV composite adhesives have advantages such as fast curing, high transparency, and good mechanical properties, they often become brittle and hard after curing, making them difficult to adapt to the repeated folding and curling of flexible electronic devices. They still have deficiencies in flexibility, bending resistance, and durability, especially for thin or thick flexible electronic devices. For example, during the use of flexible electronic devices, traditional UV adhesives may crack due to repeated folding and curling, thereby affecting the performance of the device. Summary of the Invention

[0005] In order to improve the flexibility, bending resistance and durability of UV adhesive, the present application provides a UV composite adhesive and a preparation method thereof.

[0006] In the first aspect, the present application provides a UV composite adhesive, which adopts the following technical solution: A UV composite adhesive is prepared from the following raw materials in parts by weight: 30-40 parts of epoxy modified acrylate prepolymer Polyurethane acrylic polymer 15-25 parts 10-20 parts of multifunctional acrylate monomer 4-6 parts of silicone modified acrylate prepolymer 2-4 parts of photoinitiator Adhesion promoter 1-2 parts.

[0007] By adopting the above technical solution, the UV composite adhesive prepared has good flexibility, bending resistance and durability. During the use of flexible electronic devices, the UV composite adhesive can withstand large deformation without cracking, significantly improving the reliability of the device during repeated folding and curling operations.

[0008] Among them, by combining silicone-modified acrylate prepolymers and polyurethane acrylic polymers, the UV composite adhesive has excellent flexibility and elasticity, and can maintain good bending properties after curing, making it less likely to break when repeatedly folded and bent. At the same time, the use of epoxy-modified acrylate prepolymers further improves the bending resistance. The silicone-modified acrylate prepolymer can improve the adhesion between the UV composite adhesive and the flexible substrate, ensuring that the glue will not fall off during long-term use. The multifunctional acrylate monomer optimizes the cross-linking density of the glue, so that it can still maintain stable bonding properties after multiple bending. The addition of multifunctional monomers can accelerate the curing speed and improve production efficiency. The photoinitiator can quickly initiate a polymerization reaction under ultraviolet light, allowing the UV adhesive to cure quickly and improve production efficiency. The adhesion promoter can significantly improve the adhesion between the UV adhesive and the flexible substrate, ensuring that the glue will not fall off due to deformation of the substrate during long-term use.

[0009] Preferably, the organosilicon-modified acrylate prepolymer is prepared by the following method: Mix the hydrogenated silicone oil and the solvent, heat to 100-120°C and stir, add the mixed solution of the acrylate monomer and the initiator under nitrogen protection, stir for 2-3 hours, then cool to 50-70°C and continue the reaction for 1-2 hours to obtain a silicone-modified acrylate prepolymer; The acrylic acid ester monomer consists of allyl methacrylate, allyl acrylate and ethyl acrylate in a weight ratio of 1: (1-3): 5.

[0010] By adopting this technical solution, hydrogenated silicone oil reacts and combines with acrylate monomers to form flexible silicone segments, allowing the silicone-modified acrylate prepolymer to maintain good flexibility and elasticity after curing. This improves the ability of the cured UV composite adhesive to withstand repeated folding and curling operations without breaking. At the same time, it also further improves the weather resistance and adhesion of the UV composite adhesive.

[0011] Preferably, the weight ratio of the hydrogen-containing silicone oil, the acrylate monomer and the initiator is (10-12):(15-18):0.2.

[0012] By adopting the above technical solution, the ratio of hydrogenated silicone oil, acrylate monomer and initiator in the silicone-modified acrylate prepolymer is optimized, so that each component can fully react, which can further improve the flexibility and bending resistance of the silicone-modified acrylate prepolymer, thereby enhancing the mechanical properties of the UV composite adhesive under repeated folding and curling conditions, effectively reducing the occurrence of cracks, and improving the stability and service life of flexible electronic devices.

[0013] Preferably, the epoxy-modified acrylate prepolymer is prepared by the following method: under nitrogen conditions, a cycloaliphatic epoxy resin is weighed and added to a reactor, and when the temperature is raised to 60-80° C., a mixed solution of 4-methoxyphenol, tetramethylammonium chloride and acrylate monomer is slowly added dropwise, and the addition is completed within 1-2 hours. After the addition is completed, the temperature is raised to 100-120° C., and the reaction is continued at a constant temperature until the acid value of the system drops to 3 mgKOH / g, thereby completing the reaction and obtaining the epoxy acrylate prepolymer; The acrylate monomer consists of trimethylolpropane triacrylate, glycerol triacrylate and methacrylic acid in a weight ratio of 1:(3-5):(1-2).

[0014] By adopting the above technical solution and introducing a cycloaliphatic epoxy resin, the toughness and impact resistance of the epoxy acrylate prepolymer are improved, making it less prone to brittle cracking after curing. When used with silicone-modified acrylate prepolymers and polyurethane acrylate polymers, the cured UV composite adhesive can withstand repeated folding and curling operations without breaking, while maintaining good bonding properties.

[0015] Preferably, the weight ratio of the alicyclic epoxy resin, the 4-methoxyphenol, the tetramethylammonium chloride and the acrylate monomer is (8-10):(0.01-0.03):(0.1-0.3):10.

[0016] By adopting the above technical solution, the ratio of each raw material in the epoxy-modified acrylate prepolymer is optimized, making the reaction between the alicyclic epoxy resin, 4-methoxyphenol, tetramethylammonium chloride and acrylate monomer more uniform and sufficient, which can effectively improve the flexibility and durability of the epoxy-modified acrylate prepolymer, thereby further improving the mechanical properties and bending resistance of the UV composite adhesive after curing, making it more suitable for the repeated folding and curling requirements of flexible electronic devices.

[0017] Preferably, the multifunctional acrylate monomer includes at least one of low-viscosity dipentaerythritol pentaacrylate, 2-trimethylolpropane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, bisphenol A glycerol dimethacrylate, and tripropylene glycol diacrylate.

[0018] By adopting the above technical solution, the selection of multifunctional acrylate monomers can significantly improve the crosslinking density and mechanical properties of the UV composite adhesive. Specifically, the introduction of low-viscosity dipentaerythritol pentaacrylate and 2-trimethylolpropane tetraacrylate effectively enhances the cohesion and bending resistance of the colloid while maintaining good flexibility. These multifunctional monomers form a dense three-dimensional network structure during the curing process, allowing the UV composite adhesive to maintain excellent bonding strength and stability under repeated folding and curling conditions, thereby significantly improving the service life and reliability of flexible electronic devices in dynamic deformation environments.

[0019] Preferably, the polyurethane acrylic polymer is composed of aliphatic polyurethane acrylate and modified polyurethane acrylate in a weight ratio of 1:(3-5).

[0020] By adopting the above technical solution, the type and dosage ratio of polyurethane acrylic polymers are optimized, the flexibility, bending resistance and durability of the UV composite adhesive are further improved, which can effectively reduce the generation of cracks in the colloid during repeated folding and curling, so that it can meet the diverse needs of flexible electronic devices in different application scenarios, and significantly improve the reliability and service life of flexible electronic devices.

[0021] Preferably, the photoinitiator includes at least one of 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone or trimethylbenzoyl-diphenylphosphine oxide.

[0022] By adopting the above technical solution and selecting specific photoinitiators, the curing efficiency and curing effect can be effectively improved. Specifically, photoinitiators such as 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone or trimethylbenzoyl-diphenylphosphine oxide can quickly decompose and generate free radicals under ultraviolet light, promoting the cross-linking reaction of acrylate monomers and prepolymers, thereby achieving rapid curing. In addition, these photoinitiators also have high photosensitivity and low residual content, which can ensure curing performance while reducing the impact on the performance of flexible electronic devices.

[0023] Preferably, the adhesion promoter is composed of methacrylate phosphate and isocyanatepropyltrimethoxysilane in a weight ratio of 1:(2-4).

[0024] The adhesion promoter, composed of methacrylate phosphate and isocyanatepropyltrimethoxysilane in a specific weight ratio, significantly improves the adhesion between the UV composite adhesive and flexible / ductile substrates. This combination not only enhances the adhesive strength of the UV composite adhesive to the substrate but also improves the durability of the UV composite adhesive under repeated folding and curling conditions, effectively preventing debonding or cracking caused by insufficient adhesion, thereby ensuring the stable performance of flexible electronic devices under various deformation conditions.

[0025] In a second aspect, the present application provides a method for preparing a UV composite adhesive, which adopts the following technical solution: A method for preparing UV composite adhesive includes the following steps: The epoxy modified acrylate prepolymer, the polyurethane acrylic polymer, the multifunctional acrylate monomer, the organosilicon modified acrylate prepolymer, the photoinitiator and the adhesion promoter are stirred and uniformly mixed to obtain a UV composite adhesive.

[0026] By adopting the above technical solution, the preparation method is simple and efficient, and the various components can be evenly mixed to ensure the stable performance of the UV composite adhesive. The introduction of epoxy-modified acrylate prepolymer improves the flexibility and adhesion of the composite adhesive, the polyurethane acrylic polymer enhances the bending resistance and mechanical properties, the multifunctional acrylate monomer gives the composite adhesive good crosslinking density and durability, the silicone-modified acrylate prepolymer further improves the flexibility and weather resistance, the photoinitiator ensures the effect of rapid curing, and the adhesion promoter enhances the bonding strength between the composite adhesive and the substrate. The overall solution effectively solves the problems of brittleness and poor bending resistance of traditional UV adhesives in flexible electronic device applications, and is suitable for the preparation needs of foldable and rollable devices.

[0027] In summary, this application has the following beneficial effects: 1. This application improves the flexibility, bending resistance and durability of UV composite adhesive by using epoxy-modified acrylate prepolymer, polyurethane acrylate polymer, silicone-modified acrylate prepolymer, multifunctional acrylate monomer, photoinitiator and adhesion promoter together, so that it can meet the diverse needs of flexible electronic devices in different application scenarios and significantly improve the reliability and service life of flexible electronic devices. DETAILED DESCRIPTION

[0028] Preparation Example Hydrogenated silicone oil was purchased from Nanjing Tangze Chemical Co., Ltd., model TZ1301.

[0029] Alicyclic epoxy resin: Daicel Investment Co., Ltd., 2021P, molecular weight 554, epoxy value 0.77eq / 100g.

[0030] Preparation Example 1 A silicone-modified acrylate prepolymer is prepared by the following method: 200 g of hydrogenated silicone oil and 100 g of solvent (toluene) were mixed, heated to 100° C. and stirred. Under nitrogen protection, a mixed solution of 150 g of acrylate monomer and 2 g of initiator (benzoyl peroxide) was added, stirred for 2 h, and then cooled to 50° C. and reacted for 1 h to obtain a silicone-modified acrylate prepolymer; The acrylate monomer consists of allyl methacrylate, allyl acrylate and ethyl acrylate in a weight ratio of 1:1:5.

[0031] Preparation Example 2-3 differs from Preparation Example 1 in that the types of raw materials and parameters used to prepare the silicone-modified acrylate prepolymer are different. The specific differences are shown in Table 1: Table 1 Types of raw materials and parameters for preparing silicone-modified acrylate prepolymers Preparation Example 4 A silicone-modified acrylate prepolymer. The difference between this preparation example and Preparation Example 1 is that the acrylate monomer consists of allyl methacrylate and allyl acrylate in a weight ratio of 1:1.

[0032] Preparation Example 5 A silicone-modified acrylate prepolymer. The difference between this preparation example and Preparation Example 1 is that the acrylate monomer consists of allyl methacrylate and ethyl acrylate in a weight ratio of 1:5.

[0033] Preparation Example a An epoxy-modified acrylate prepolymer is prepared by the following method: Under nitrogen conditions, 400 g of alicyclic epoxy resin was weighed and added to a reactor. When the temperature reached 60° C., a mixture of 0.5 g of 4-methoxyphenol, 5 g of tetramethylammonium chloride, and 500 g of acrylate monomer was slowly added dropwise. The addition was completed within 1 hour. After the addition was completed, the temperature was raised to 100° C. and the reaction was continued at this temperature until the acid value of the system dropped to 3 mgKOH / g, thereby completing the reaction and obtaining an epoxy acrylate prepolymer. The acrylate monomer consists of trimethylolpropane triacrylate, glycerol triacrylate and methacrylic acid in a weight ratio of 1:3:1.

[0034] Preparation Example bc differs from Preparation Example a in that the types of raw materials and parameters used to prepare the epoxy-modified acrylate prepolymer are different. The specific differences are shown in Table 2: Table 2 Types of raw materials and parameters for preparing silicone-modified acrylate prepolymers Preparation Example d An epoxy-modified acrylate prepolymer. The difference between this preparation example and preparation example a is that the acrylate monomer consists of trimethylolpropane triacrylate and glycerol triacrylate in a weight ratio of 1:3.

[0035] Preparation Example e An epoxy-modified acrylate prepolymer. The difference between this preparation example and preparation example a is that the acrylate monomer consists of trimethylolpropane triacrylate and methacrylic acid in a weight ratio of 1:1. Example

[0036] Aliphatic polyurethane acrylate was purchased from Ruisheng New Materials Co., Ltd., model RU-2041B.

[0037] Modified polyurethane acrylate was purchased from Ruisheng New Materials Co., Ltd., model RU-2034B.

[0038] Example 1 A UV composite adhesive is prepared by the following method: 300 g of the epoxy-modified acrylate prepolymer from Preparation Example a, 150 g of a polyurethane acrylic polymer, 100 g of a multifunctional acrylate monomer (2-trimethylolpropane tetraacrylate), 40 g of the silicone-modified acrylate prepolymer from Preparation Example 1, 20 g of a photoinitiator (1-hydroxy-cyclohexyl-phenyl ketone) and 10 g of an adhesion promoter were stirred and uniformly mixed to obtain a UV composite adhesive.

[0039] The polyurethane acrylic polymer consists of aliphatic polyurethane acrylate and modified polyurethane acrylate in a weight ratio of 1:3.

[0040] The adhesion promoter is composed of methacrylate phosphate and isocyanatepropyltrimethoxysilane in a weight ratio of 1:2.

[0041] The difference between Example 2-3 and Example 1 is that the types of raw materials and parameters used to prepare the UV composite adhesive are different. The specific differences are shown in Table 3: Table 3 Types of raw materials and parameters for preparing UV composite adhesive Example 4 A UV composite adhesive. The difference between this embodiment and Example 1 is that the organosilicon-modified acrylate prepolymer comes from Preparation Example 4.

[0042] Example 5 A UV composite adhesive. The difference between this embodiment and Example 1 is that the organosilicon-modified acrylate prepolymer comes from Preparation Example 5.

[0043] Example 6 A UV composite adhesive. The difference between this embodiment and Example 1 is that the epoxy-modified acrylate prepolymer comes from Preparation Example d.

[0044] Example 7 A UV composite adhesive. The difference between this embodiment and Example 1 is that the epoxy-modified acrylate prepolymer comes from Preparation Example e.

[0045] Comparative Example Comparative Example 1 A UV composite adhesive. The difference between this comparative example and Example 1 is that bisphenol A epoxy resin is used instead of polyurethane acrylic polymer.

[0046] Bisphenol A epoxy resin was purchased from Nanya Electronics Co., Ltd., NPEL-128G, with an epoxy value of 0.51eq / 100g.

[0047] Comparative Example 2 A UV composite adhesive. The difference between this comparative example and Example 1 is that ethyl acetate is used instead of polyurethane acrylic polymer.

[0048] Comparative Example 3 A UV composite adhesive. The difference between this comparative example and Example 1 is that butyl acrylate is used instead of the multifunctional acrylate monomer.

[0049] Detection method / test method Adhesive strength: Refer to GB / T 7124 to test its tensile shear strength.

[0050] Bending resistance test: After curing the UV composite adhesives of Examples 1-7 and Comparative Examples 1-3, a 100,000-cycle bending test was performed, with each bending angle being 90°. The state of the samples after the test was observed to see if there were obvious cracks or breakages. If yes, it indicates that the samples have good flexibility.

[0051] Durability test: After curing, the UV composite adhesives prepared in Examples 1-7 and Comparative Examples 1-3 were placed in an environment of 85°C / 85% humidity for 1000 hours. The front and back bonding strength, flexibility, and bending resistance were tested. The experimental data are shown in Table 4: Table 4 Experimental data of Examples 1-7 and Comparative Examples 1-3 Comparing Example 1 with Comparative Examples 1-3, the bonding performance of Comparative Examples 1-3 is low and fails the bending resistance test, indicating that in this application, by combining polyurethane acrylic polymer, multifunctional acrylate monomer, silicone modified acrylate prepolymer with photoinitiator, epoxy modified acrylate prepolymer and adhesion promoter, the UV composite adhesive obtained has good bonding performance, flexibility, bending resistance and aging resistance.

[0052] It can be seen from the experimental data of Examples 1 and 4-5 that the organosilicon-modified acrylate prepolymer prepared by the present application can improve the bonding performance, flexibility, bending resistance and aging resistance of the UV composite adhesive.

[0053] It can be seen from the experimental data of Example 1 and Examples 6-7 that the epoxy-modified acrylate prepolymer prepared by the present application can improve the bonding performance, flexibility, bending resistance and aging resistance of the UV composite adhesive.

[0054] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A UV composite adhesive, characterized in that: Prepared from the following raw materials in parts by weight: 30-40 parts of epoxy modified acrylate prepolymer Polyurethane acrylic polymer 15-25 parts 10-20 parts of multifunctional acrylate monomer 4-6 parts of silicone modified acrylate prepolymer 2-4 parts of photoinitiator Adhesion promoter 1-2 parts.

2. The UV composite adhesive according to claim 1, characterized in that: The organosilicon-modified acrylate prepolymer is prepared by the following method: Mix the hydrogenated silicone oil and the solvent, heat to 100-120°C and stir, add the mixed solution of the acrylate monomer and the initiator under nitrogen protection, stir for 2-3 hours, then cool to 50-70°C and continue the reaction for 1-2 hours to obtain a silicone-modified acrylate prepolymer; The acrylic acid ester monomer is composed of allyl methacrylate, allyl acrylate and ethyl acrylate in a weight ratio of 1: (1-3):

5.

3. The UV composite adhesive according to claim 2, characterized in that: The weight ratio of the hydrogenated silicone oil, the acrylate monomer and the initiator is (10-12): (15-18): 0.

2.

4. The UV composite adhesive according to claim 1, characterized in that: The epoxy-modified acrylate prepolymer is prepared by the following method: Under nitrogen, a cycloaliphatic epoxy resin was weighed and added to a reactor. When the temperature reached 60-80°C, a mixture of 4-methoxyphenol, tetramethylammonium chloride, and acrylate monomer was slowly added dropwise. The addition was completed within 1-2 hours. After the addition was completed, the temperature was raised to 100-120°C and the reaction was continued at this temperature until the acid value of the system dropped to 3 mgKOH / g, thereby completing the reaction and obtaining an epoxy acrylate prepolymer. The acrylate monomer is composed of trimethylolpropane triacrylate, glycerol triacrylate and methacrylic acid in a weight ratio of 1: (3-5): (1-2).

5. The UV composite adhesive according to claim 4, characterized in that: The weight ratio of the alicyclic epoxy resin, the 4-methoxyphenol, the tetramethylammonium chloride and the acrylate monomer is (8-10): (0.01-0.03): (0.1-0.3):

10.

6. The UV composite adhesive according to claim 1, characterized in that: The multifunctional acrylate monomer includes at least one of low-viscosity dipentaerythritol pentaacrylate, 2-trimethylolpropane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, bisphenol A glycerol dimethacrylate, and tripropylene glycol diacrylate.

7. The UV composite adhesive according to claim 1, characterized in that: The polyurethane acrylic polymer consists of aliphatic polyurethane acrylate and modified polyurethane acrylate in a weight ratio of 1:(3-5).

8. The UV composite adhesive according to claim 1, characterized in that: The photoinitiator includes at least one of 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone or trimethylbenzoyl-diphenylphosphine oxide.

9. The UV composite adhesive according to claim 1, characterized in that: The adhesion promoter is composed of methacrylate phosphate and isocyanate propyltrimethoxysilane in a weight ratio of 1: (2-4).

10. A method for preparing the UV composite adhesive according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: The epoxy modified acrylate prepolymer, the polyurethane acrylic polymer, the multifunctional acrylate monomer, the organosilicon modified acrylate prepolymer, the photoinitiator and the adhesion promoter are stirred and uniformly mixed to obtain a UV composite adhesive.

Images