High-strength optical adhesive for extreme conditions, its preparation method and application

Abstract

This invention discloses a high-adhesion optical adhesive for extreme conditions, its preparation method, and its application, belonging to the field of optical adhesive technology. It comprises the following components in parts by weight: 20-30 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 15-25 parts of 1,4-butanediol dimethacrylate, 15-25 parts of tetraethylene glycol dimethacrylate, 5-10 parts of α-methacrylic acid, 5-10 parts of hydroxyethyl methacrylate, 2-5 parts of vinyltriethoxysilane, 0.1-0.5 parts of 1-hydroxycyclohexylphenyl ketone, 0.1-0.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.3-0.5 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime). The optical adhesive of the present invention has excellent bonding performance and can prevent the bonded components from debonding and causing cohesive failure at the bonding joint in humid, steamy, or chemical solvent environments.

Description

Technical Field

[0001] This invention relates to the field of optical adhesive technology, and in particular to a high-adhesion optical adhesive for extreme conditions, its preparation method, and its application. Background Technology

[0002] OCA (Optical Clear Adhesive) is a special adhesive used for bonding transparent optical components (such as lenses). It requires characteristics such as colorless transparency, light transmittance of over 90%, good bonding strength, curing at room temperature or medium temperature, and low curing shrinkage. Acrylic UV-curable adhesives are widely used in high-end fields such as electronic packaging, optical devices, medical devices, automotive industry, and aerospace due to their advantages of fast curing speed, high bonding strength, and wide applicability. However, with the development of technology and the increasing complexity of application environments, especially under extreme conditions (such as high humidity and high temperature environments), traditional acrylic UV-curable adhesives often fail to meet stringent performance requirements, resulting in a significant decrease in bonding strength and durability, affecting product reliability and lifespan.

[0003] Extreme application environments place higher performance demands on adhesives. Firstly, in high-humidity and high-temperature environments, adhesives need excellent water and moisture resistance to prevent moisture penetration that could lead to decreased bond strength and material degradation. Secondly, under high-temperature conditions, adhesives should possess good thermal stability and heat resistance to ensure they maintain their adhesive properties and physical characteristics even at high temperatures. Furthermore, high bond strength (shear strength greater than 10 GPa) is a key indicator to ensure that structural components do not detach or fail under complex stress conditions.

[0004] For example, invention patent CN117586733A discloses a high-strength adhesive with environmental durability and its preparation method. This method prepares a one-component epoxy resin adhesive, effectively solving problems such as low bonding strength of one-component adhesives to composite materials and the decrease in bonding strength due to environmental influences. It exhibits excellent bonding performance to aluminum alloys and composite materials, maintains high shear strength even after environmental durability testing, and is convenient to apply and has easily controllable processability. This environmentally durable adhesive includes epoxy resin, diluent, curing agent, coupling agent, and additives. Although it maintains bonding stability after various environmental aging treatments, the preparation process is complex and not suitable for OCA optical bonding systems.

[0005] Traditional acrylic UV-curable adhesives exhibit limitations under these extreme conditions. The main reasons include: acrylic substrates are prone to hydrolysis in high humidity and heat environments, leading to adhesive performance degradation; and acrylic materials are susceptible to thermal degradation at high temperatures, resulting in a significant decrease in bond strength. Therefore, developing an acrylic UV-curable adhesive that maintains high bond strength under extreme conditions such as high humidity and heat has become a current research hotspot and challenge in the adhesive field.

[0006] To address these challenges, researchers have recently significantly improved the performance of acrylate UV-curable adhesives by introducing functional monomers, modified resins, and nanofillers. For example, introducing silicon- or fluorine-containing functional monomers enhances the moisture and heat resistance of adhesives; modifying epoxy resins or polyurethane acrylates improves the toughness and bond strength; and adding nanofillers such as nano-silica and nano-alumina enhances the mechanical properties and thermal stability of adhesives. However, while these modifications have improved adhesive performance to some extent, they still fall short of fully meeting the requirements for high bond strength under extreme conditions.

[0007] Therefore, there is an urgent need to develop an acrylic UV-curable adhesive that can maintain high bond strength (shear strength greater than 10 GPa) under extreme conditions such as high humidity and high temperature, in order to meet the stringent performance requirements of adhesives in high-end applications. This is not only of great significance for improving product reliability and service life, but also provides new research directions and technical support for the development of adhesive technology.

[0008] For example, invention patent CN117701195A discloses a high-adhesion, bend-resistant OCA adhesive, its preparation method, and its application. It uses isooctyl acrylate, hydroxybutyl acrylate, dimethylaminoethyl methacrylate, an adhesion modifier, an initiator, and a first solvent to synthesize an acrylic adhesive under heating conditions. This effectively solves the problems of edge lifting and delamination caused by slippage between layers in foldable display modules due to insufficient adhesion. The addition of an adhesion modifier with numerous polar groups further improves the OCA adhesive's adhesion to various substrates and its resistance to water whitening, as well as its aging resistance in foldable display modules. However, this preparation process uses volatile monomers, and the added isooctyl acrylate, which has an irritating odor, is used to adjust chain segment flexibility. These factors can have adverse environmental impacts, and the complex monomer composition is detrimental to the long-term storage of the prepolymer.

[0009] Acrylic ester systems have been extensively studied for their adhesive properties due to their low viscosity, rapid curing, and ease of formulation control. However, there is currently no optical adhesive that offers good weather resistance (heat, cold, and moisture resistance), ease of use, and high bond strength. Summary of the Invention

[0010] This invention provides a high-adhesion optical adhesive for extreme conditions, its preparation method, and its application, addressing the urgent need in the field of optical component bonding for environmentally stable, high-adhesion, adjustable refractive index, and fast-curing optical adhesives.

[0011] This invention, through structural design of acrylate resin molecules and selection of various acrylate monomers, particularly the synergistic effect of multiple functional monomers in specific proportions, yields an acrylic resin for optical components. The optical adhesive prepared from this resin is applied to various glass bonding applications, such as windshields, tempered glass, and K9 glass for optical components. It not only possesses a matching refractive index but also exhibits excellent bonding performance and weather resistance (heat resistance, cold resistance, and moisture resistance). The specific technical solution is as follows:

[0012] A high-strength optical adhesive for extreme conditions comprises the following components in parts by weight: 20-30 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 15-25 parts of 1,4-butanediol dimethacrylate, 15-25 parts of tetraethylene glycol dimethacrylate, 5-10 parts of α-methacrylic acid, 5-10 parts of hydroxyethyl methacrylate, 2-5 parts of vinyltriethoxysilane, 0.1-0.5 parts of 1-hydroxycyclohexylphenyl ketone, 0.1-0.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.3-0.5 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime).

[0013] Preferably, a high-adhesion optical adhesive for extreme conditions comprises the following components in parts by weight: 30 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 25 parts of 1,4-butanediol dimethacrylate, 25 parts of tetraethylene glycol dimethacrylate, 5 parts of α-methacrylic acid, 10 parts of hydroxyethyl methacrylate, 5 parts of vinyltriethoxysilane, 0.3 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime), 0.3 parts of 1-hydroxycyclohexylphenyl ketone, and 0.3 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0014] A method for preparing a high-adhesion optical adhesive for extreme conditions includes the following steps:

[0015] Step 1: Mix 2-methyl-6-methylene-1,7-octadien-3-one, 1,4-butanediol dimethacrylate, α-methacrylic acid, tetraethylene glycol dimethacrylate, vinyltriethoxysilane, and hydroxyethyl methacrylate to obtain a monomer prepolymer.

[0016] Step 2: Mix the above monomer prepolymer, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] acetone-1-(O-acetyl oxime), 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenyl-1-propanone for 30 minutes to obtain the final product.

[0017] In step one, 2-methyl-6-methylene-1,7-octadien-3-one is selected as the main monomer, which ensures that the optical adhesive has excellent environmental stability (maintains high bonding strength under humid heat and high temperature). Different monomers with different refractive indices can also be obtained by changing its content.

[0018] The first step involves a flexible monomer consisting of hydroxyethyl methacrylate and vinyltriethoxysilane mixed in a certain ratio, which gives the optical adhesive excellent bonding strength.

[0019] The application of optical adhesives in the fabrication of optical components includes the following steps:

[0020] Step A: Place the substrate to be bonded horizontally;

[0021] Step B: Uniformly coat the optical adhesive obtained according to claim 1 or 2 onto the horizontally placed substrate in step A;

[0022] Step C: Cover the substrate coated with optical adhesive from step B with another substrate, and continuously move to remove air bubbles to obtain the bonded optical element;

[0023] Step D: Place under 365nm ultraviolet light at 20mw / cm 2 Curing under light intensity for 10 minutes yields cured optical components.

[0024] This invention, through a rational formulation design, selects 2-methyl-6-methylene-1,7-octadien-3-one as the main monomer, ensuring that the optical adhesive exhibits excellent environmental stability (maintaining high adhesive strength even under humid heat and high temperatures) and an adjustable refractive index. Furthermore, by blending it with hydroxyethyl methacrylate and vinyltriethoxysilane in a specific ratio, the optical adhesive achieves excellent adhesive strength (shear strength greater than 10 GPa). In addition, ultraviolet light initiation allows the optical adhesive to cure rapidly at room temperature. Moreover, the aforementioned optical adhesive maintains high-strength adhesion to a variety of transparent materials without detachment, demonstrating its excellent applicability and environmental stability.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] 1. Optical components made from adhesives using a specific ratio of multifunctional acrylate monomers exhibit excellent light transmittance, mechanical properties, and weather resistance. High-performance optical components made from UV-cured adhesives using a specific ratio of these adhesives can overcome bottlenecks, while also possessing adjustable refractive indexes and stronger bonding performance, thereby reducing damage to optical components. These adhesives have the potential to be applied to the bonding of optically transparent components (such as prisms, lenses, and mirrors) and the production of precision optical assemblies.

[0027] 2. The preparation process of the UV-curable optical adhesive for high-performance optical components with this specific ratio is simple and the raw materials are easy to obtain; the refractive index of the UV-curable optical adhesive for high-performance optical components with this specific ratio is 1.478, and it has low viscosity, with a viscosity of 7 mPa·s at 25℃.

[0028] 3. Optical adhesives can be used directly as adhesives for optical components. They have excellent bonding properties and can prevent bonding components from detaching and causing cohesive failure at the bonding joint even in humid, steamy, or chemical solvent environments. Attached Figure Description

[0029] Figure 1 Optical adhesive shears prepared in different proportions (glass size: 50x50x100mm);

[0030] Figure 2 Optical adhesive shears prepared for different photoinitiators (glass size: 50x50x100mm);

[0031] Figure 3 For the optical adhesive of Example 1, different glass tensile-shear tests were performed (glass size: 50x50x100mm).

[0032] Figure 4 For the optical adhesive pull-shear test of Example 1 under humid and hot conditions (glass size: 50x50x100mm);

[0033] Figure 5 The optical adhesive pull-shear test of Example 1 under solvent conditions (glass size: 50x50x100mm). Detailed Implementation

[0034] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described herein. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment provides a high-strength optical adhesive for extreme conditions, comprising the following components in parts by weight: 30 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 25 parts of 1,4-butanediol dimethacrylate, 25 parts of tetraethylene glycol dimethacrylate, 5 parts of α-methacrylic acid, 10 parts of hydroxyethyl methacrylate, 5 parts of vinyltriethoxysilane, 0.3 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime), 0.3 parts of 1-hydroxycyclohexylphenyl ketone, and 0.3 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0037] The method for preparing the optical adhesive in this embodiment includes the following steps:

[0038] Step 1: Mix 2-methyl-6-methylene-1,7-octadien-3-one, 1,4-butanediol dimethacrylate, α-methacrylic acid, tetraethylene glycol dimethacrylate, vinyltriethoxysilane, and hydroxyethyl methacrylate to obtain a monomer prepolymer.

[0039] Step 2: Mix the above monomer prepolymer, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] acetone-1-(O-acetyl oxime), 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenyl-1-propanone for 30 minutes to obtain the final product.

[0040] Example 2

[0041] This embodiment provides a high-strength optical adhesive for extreme conditions, comprising the following components in parts by weight: 25 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 15 parts of 1,4-butanediol dimethacrylate, 15 parts of tetraethylene glycol dimethacrylate, 10 parts of α-methacrylic acid, 5 parts of hydroxyethyl methacrylate, 2 parts of vinyltriethoxysilane, 0.1 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime), 0.5 parts of 1-hydroxycyclohexylphenyl ketone, and 0.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0042] The preparation method of the optical adhesive in this embodiment is the same as that in Example 1.

[0043] Example 3

[0044] This embodiment provides a high-strength optical adhesive for extreme conditions, comprising the following components in parts by weight: 20 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 20 parts of 1,4-butanediol dimethacrylate, 20 parts of tetraethylene glycol dimethacrylate, 8 parts of α-methacrylic acid, 8 parts of hydroxyethyl methacrylate, 4 parts of vinyltriethoxysilane, 0.5 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime), 0.1 parts of 1-hydroxycyclohexylphenyl ketone, and 0.4 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0045] The preparation method of the optical adhesive in this embodiment is the same as that in Example 1.

[0046] The composition (by mass) of the acrylic resin in Comparative Examples 1-4 is shown in Table 1. The 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] acetone-1-(O-acetyl oxime), 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone in Comparative Examples 1-4 are the same as those in Example 1.

[0047] Table 1. Composition (by weight) of acrylic resins in the examples and comparative examples.

[0048]

[0049]

[0050] The compositions (by weight) of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] acetone-1-(O-acetyl oxime), 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenyl-1-propanone in Comparative Examples 5-6 are shown in Table 2. The compositions (by weight) of acrylic resins in Comparative Examples 5-6 are the same as those in Example 1.

[0051] Table 2. Composition (by weight) of photoinitiators in the examples and comparative examples.

[0052]

[0053] Application examples: Optical adhesive shears prepared in different proportions (glass size: 50x50x100mm) are shown below. Figure 1 As shown; optical adhesive shears (glass size: 50x50x100mm) prepared with different photoinitiators are shown below. Figure 2 As shown; Example 1: Tight-shear test of optical adhesive on different types of glass (glass size: 50x50x100mm) Figure 3As shown; the optical adhesive tensile-shear test of Example 1 under humid and hot conditions (glass size: 50x50x100mm) is as follows. Figure 4 As shown; the optical adhesive tensile-shear test of Example 1 under solvent conditions (glass size: 50x50x100mm) is as follows. Figure 5 As shown.

[0054] From Tables 1 and 2, and from... Figures 1 to 5 The test characterization results show that, within the specified proportions, variations in the components 2-methyl-6-methylene-1,7-octadien-3-one, 1,4-butanediol dimethacrylate, tetraethylene glycol dimethacrylate, α-methacrylic acid, hydroxyethyl methacrylate, and vinyltriethoxysilane significantly affect viscosity and tensile shear strength. Among these, 2-methyl-6-methylene-1,7-octadien-3-one contributes primarily to the refractive index due to its unique molecular structure, which exhibits excellent optical transparency and weather resistance. 1,4-Butanediol dimethacrylate and tetraethylene glycol dimethacrylate are flexible crosslinking agents that can improve the adhesive strength of optical adhesives while maintaining high cohesive strength. These two monomers form a flexible network structure during curing, increasing the toughness and durability of the adhesive layer. α-Methacrylic acid provides an acidic environment, which is conducive to the hydrolysis and further reaction of vinyltriethoxysilane, enhancing adhesion to inorganic materials (such as glass and metals). Furthermore, α-methacrylic acid also plays a role in regulating viscosity and reaction rate in optical adhesives, making them more stable and easier to handle during application. Hydroxyethyl methacrylate (HYMA) possesses excellent hydrophilicity and adhesion; its hydroxyl functional groups can undergo cross-linking reactions with other components, improving the adhesive strength and water resistance of the optical adhesive. In optical adhesives, HYMA helps improve the adhesion of the adhesive layer, maintaining good bonding performance even in humid environments. Vinyltriethoxysilane, as a coupling agent, acts as a bridge in optical adhesives; its vinyl and ethoxy groups can react with organic and inorganic substrates respectively, enhancing the adhesive strength between the optical adhesive and glass. In the acidic environment of α-methacrylic acid, vinyltriethoxysilane hydrolyzes more readily and forms strong chemical bonds with the glass surface. Tensile-shear tests show that the improved optical adhesive not only maintains high adhesive strength but also exhibits excellent environmental resistance, capable of withstanding various harsh conditions. All these improvements and optimizations result in a novel optical adhesive that excels in optical transparency, weather resistance, bond strength, and chemical resistance, making it suitable for bonding high-performance optical components.

[0055] For optical adhesives, the color and workability of the system are crucial. The photoinitiators were optimized in Table 2. Although 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone can both generate free radicals under 365nm ultraviolet light, their absorption peaks are not near the 365nm wavelength. Therefore, their initiation efficiency under 365nm ultraviolet light is not as good as that of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] ethyl ketone-1-(O-acetyl oxime). Furthermore, during the photocuring process, the photoinitiator 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyl oxime) exhibits less yellowing, making it ideal for photocurable products requiring high transparency and low color change. Ultimately, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyl oxime) was chosen to achieve long-term operation and rapid curing within 10 minutes. All of the above demonstrates that, within the specified proportions of this invention, the urgent need in the field of optical component bonding for optical adhesives with high bond strength, resistance to ambient temperature, adjustable refractive index, and rapid room-temperature curing is effectively addressed.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Other embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of the present invention.

Claims

1. A high-adhesion optical adhesive for extreme conditions, characterized in that... The product comprises the following components in parts by weight: 20-30 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 15-25 parts of 1,4-butanediol dimethacrylate, 15-25 parts of tetraethylene glycol dimethacrylate, 5-10 parts of α-methacrylic acid, 5-10 parts of hydroxyethyl methacrylate, 2-5 parts of vinyltriethoxysilane, 0.1-0.5 parts of 1-hydroxycyclohexylphenyl ketone, 0.1-0.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.3-0.5 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime).

2. The high-adhesion optical adhesive for extreme conditions according to claim 1, characterized in that... The product comprises the following components in parts by weight: 30 parts of 2-methyl-6-methylene-1,7-octadien-3-one, 25 parts of 1,4-butanediol dimethacrylate, 25 parts of tetraethylene glycol dimethacrylate, 5 parts of α-methacrylic acid, 10 parts of hydroxyethyl methacrylate, 5 parts of vinyltriethoxysilane, 0.3 parts of 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone-1-(O-acetyloxime), 0.3 parts of 1-hydroxycyclohexylphenyl ketone, and 0.3 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone.

3. A method for preparing a high-adhesion optical adhesive for extreme conditions as described in claim 1 or 2, characterized in that... Includes the following steps: Step 1: Mix 2-methyl-6-methylene-1,7-octadien-3-one, 1,4-butanediol dimethacrylate, α-methacrylic acid, tetraethylene glycol dimethacrylate, vinyltriethoxysilane, and hydroxyethyl methacrylate to obtain a monomer prepolymer. Step 2: Mix the above monomer prepolymer, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] ethyl ketone-1-(O-acetyl oxime), 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

4. The application of the optical adhesive according to claim 1 or 2 in the fabrication of optical components, characterized in that... Includes the following steps: Step A: Place the substrate to be bonded horizontally; Step B: Uniformly coat the optical adhesive obtained according to claim 1 or 2 onto the horizontally placed substrate in step A; Step C: Cover the substrate coated with optical adhesive from step B with another substrate, and continuously move to remove air bubbles to obtain the bonded optical element; Step D: Place under 365nm ultraviolet light at 20mw / cm 2 Curing under light intensity for 10 minutes yields cured optical components.

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