Octyl acrylate-based wet viscous adhesive and preparation method thereof

Abstract

The invention discloses an octyl acrylate-based wet viscous adhesive and a preparation method thereof, and belongs to the technical field of adhesives. The adhesive is composed of octyl acrylate, a functional monomer, a cationic monomer, a dual cross-linking agent, mixed tackifying resin and other raw materials, a UV-thermal step-by-step polymerization process is adopted, a uniform pre-polymerized network is formed through low-strength UV pre-polymerization, then a thermal polymerization supplementary reaction is performed, and an isocyanate-epoxy composite curing agent compact cross-linked structure is matched, so that the adhesive is prepared. The invention aims to solve the problems of weak wet adhesive strength, non-uniform crosslinking and insufficient water resistance of the existing product. The product has excellent wet adhesion performance, high cohesive strength and environmental protection property, the peel strength is greater than or equal to 8.65 N / 25mm in a humid environment at 37 DEG C, the damp-heat aging resistance retention rate is greater than 85%, the VOC emission is low, and the product is suitable for multiple scenes such as medical dressing, flexible electronic packaging, humid environment packaging and the like.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and more particularly to an octyl acrylate wet adhesive and its preparation method. Background Technology

[0002] Wet adhesives are widely used in medical dressings, flexible electronic packaging, and packaging for humid environments. Among them, acrylate adhesives have become the mainstream due to their excellent transparency and strong weather resistance.

[0003] However, existing technologies have significant shortcomings: First, its wet adhesion performance is weak. The water film on the surface of the wet substrate will block the interfacial interaction between the adhesive layer and the substrate, resulting in a significant decrease in peel strength, which makes it difficult to meet the requirements of long-term wet use. Second, the crosslinking system is not designed properly. Single thermal polymerization or UV polymerization can easily cause uneven crosslinking, either resulting in insufficient cohesive strength causing the adhesive layer to slip, or excessive loss of viscosity affecting the wetting effect. Third, there is an imbalance between water resistance and environmental friendliness. Traditional solvent-based formulations have high VOC emissions and are prone to swelling and failure after water immersion. At the same time, single tackifying resins cannot balance initial tack, holding power and peel strength, which limits their adaptability to multiple substrates and complex humid environments. Targeted optimization and upgrading are urgently needed. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an octyl acrylate-based wet adhesive and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention first proposes an octyl acrylate-based wet-adhesive adhesive, prepared from raw materials comprising the following parts by weight: 25-35 parts of octyl acrylate; Acrylic acid 2.5-3.5 parts; Hydroxyethyl methacrylate, 1.0-2.0 parts; 0.2-0.5 parts of cationic monomer; 0.2-0.5 parts of active ester crosslinking monomer; Crosslinking agent 0.004-0.006 parts; Photoinitiator 0.15-0.25 parts; 0.8-1.2 parts of thermal initiator; 1.4-1.7 parts of tackifying resin; 1.3-1.5 parts of curing agent; And 40-50 parts of solvent; Wherein, the cationic monomer is benzylvinyltrimethylammonium chloride, the active ester crosslinking monomer is N-hydroxysuccinimide acrylate, and the crosslinking agent is N,N-methylenebisacrylamide; The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the thermal initiator is lauroyl peroxide.

[0006] Preferably, the molar ratio of octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer and active ester crosslinking monomer is 100-120:25-30:7-9:0.8-1.2:0.9-1.3.

[0007] Preferably, the tackifying resin is an esterified rosin, a terpene phenol resin, and a liquid rosin resin in a mass ratio of 5-7:6-8:1-3.

[0008] Preferably, the curing agent is an isocyanate curing agent and an epoxy curing agent in a mass ratio of 5-7:1.

[0009] Preferably, the solvent is a mixture of deionized water, ethyl acetate and toluene in a volume ratio of 1:7-9:5-7.

[0010] The present invention also proposes a method for preparing the aforementioned octyl acrylate wet tack adhesive, comprising the following steps: S1. Preparation of polymer solution: Octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer, active ester crosslinking monomer and solvent are mixed and dissolved under an inert atmosphere to obtain monomer mixture; A crosslinking agent and a photoinitiator were added to a monomer mixture, stirred until homogeneous, and then irradiated with ultraviolet light to form a prepolymer network. Subsequently, a thermal initiator was added, and the mixture was heated to carry out a thermal polymerization reaction. After the reaction was completed, a polymer solution was obtained.

[0011]

[0012] Octyl acrylate provides basic viscosity and flexibility (low Tg), while acrylic acid introduces carboxyl groups, enhancing the polar interaction with the substrate. Hydroxyethyl methacrylate introduces hydroxyl groups, providing reaction sites for subsequent crosslinking. The photoinitiator decomposes under 40-60W UV light to generate free radicals, initiating copolymerization of monomers with crosslinking agents (N,N-methylenebisacrylamide) and reactive ester crosslinking monomers (N-hydroxysuccinimide acrylate), initially forming a mildly crosslinked prepolymer network. This prevents monomer burst polymerization during subsequent thermal polymerization, ensuring a uniform polymer structure.

[0013] At 85-95℃, the thermal initiator decomposes, driving the complete polymerization of the remaining monomers. At the same time, the hydroxyl groups of hydroxyethyl methacrylate react with the active ester groups, improving the crosslinking network, enhancing the cohesive strength of the polymer, and preventing the adhesive layer from breaking in the wet state.

[0014]

[0015] S2. Adhesive preparation: Add tackifying resin, curing agent and antioxidant to polymer solution, stir evenly to obtain the wet tack adhesive.

[0016] Preferably, in step S1, the power of ultraviolet light irradiation is 40-60W, and the irradiation time is 10-20min; the temperature of the thermal polymerization reaction is 85-95℃, and the reaction time is 2-4h.

[0017] Preferably, in step S1, before ultraviolet irradiation, the monomer mixture is heated to 55-65°C and stirred for 1-2 hours.

[0018] Preferably, the step S2 is followed by a tape forming step: The wet adhesive is applied to a substrate and then dried and cured to obtain a wet adhesive tape. The drying conditions are 90-110℃ for 2-5 minutes and the curing conditions are 35-45℃ for 2-4 days.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention significantly improves wet adhesion performance, overcoming the pain point of adhesion attenuation in wet environments in existing technologies. Through the electrostatic adsorption of cationic monomers and the hydrogen bonding of functional monomers, it synergistically overcomes the water film barrier on wet surfaces. Combined with a three-dimensional network of tackifying resins to optimize interfacial adhesion, the peel strength of the adhesive on wet substrates is increased by more than 30%, and the holding power remains for 24 hours without detachment. Compared to existing technologies that are susceptible to wetting failure and insufficient cohesion due to water film effects, this invention achieves a balance between wet adhesion and cohesive strength, making it suitable for wet applications such as medical and flexible displays.

[0020] 2. This invention employs a UV-thermal stepwise polymerization process to construct a uniform and dense crosslinked network, solving the problems of uneven crosslinking and chain segment defects in existing technologies. Low-intensity UV prepolymerization forms the basic network, while thermal polymerization completes the reaction, avoiding chain breakage or loose crosslinking caused by single UV polymerization. Combined with the synergistic effect of dual crosslinking agents and curing agents, the crosslinking density is increased by 40%, significantly enhancing the water resistance and long-term stability of the adhesive layer. Compared to the swelling and peeling phenomena easily occurring in existing technologies, this invention, after curing at 35-45℃ for 2-4 days, can withstand long-term humid environments without significant attenuation of cohesive strength.

[0021] 3. This invention balances environmental friendliness and application adaptability, overcoming the shortcomings of existing technologies such as high VOC emissions and limited application scenarios. The mixed solvent system reduces the release of volatile organic compounds, aligning with the trend towards low-VOC environmental protection. Furthermore, by adjusting the monomer ratio and tackifying resin proportion, it can be flexibly adapted to different substrates (metals, polymers, skin, etc.). Compared to the single-performance-oriented design of existing technologies, this invention achieves a multi-dimensional balance of "adhesion-cohesion-environmental protection" while maintaining high transparency (light transmittance ≥95%), increasing production efficiency by 20% and meeting the needs of multiple fields such as medical dressings and flexible electronic packaging.

[0022] In summary, this invention overcomes the barrier of wet water films through the synergistic effect of cationic monomers and functional monomers, significantly improving adhesion and holding power. It employs a UV-thermal stepwise polymerization process to construct a uniform and dense cross-linked network, enhancing water resistance and cohesive stability. Optimized solvent and component ratios reduce VOC emissions while maintaining high transparency and compatibility with multiple substrates. This invention addresses the pain points of existing technologies, such as wet adhesion attenuation, uneven cross-linking, and limited application scenarios, effectively meeting the needs of various fields including medical and flexible electronics. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Example 1: An octyl acrylate-based wet tack adhesive, comprising the following raw materials by weight: 35 kg of octyl acrylate; 2.5 kg of acrylic acid; Hydroxyethyl methacrylate 2.0 kg; 0.2 kg of cationic monomer; 0.5 kg of active ester crosslinking monomer; Crosslinking agent 0.004 kg; 0.25 kg of photoinitiator; 0.8 kg of thermal initiator; 1.7 kg of tackifying resin; 1.3 kg of curing agent; And 50 kg of solvent; Wherein, the cationic monomer is benzylvinyltrimethylammonium chloride, the active ester crosslinking monomer is N-hydroxysuccinimide acrylate, and the crosslinking agent is N,N-methylenebisacrylamide; The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the thermal initiator is lauroyl peroxide.

[0025] The tackifying resin is an esterified rosin, a terpene phenol resin, and a liquid rosin resin in a mass ratio of 5:8:1.

[0026] The curing agent is an isocyanate curing agent and an epoxy curing agent in a mass ratio of 7:1.

[0027] The solvent is a mixture of deionized water, ethyl acetate and toluene in a volume ratio of 1:7:7.

[0028] Includes the following steps: S1. Preparation of polymer solution: Octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer, active ester crosslinking monomer and solvent are mixed and dissolved under an inert atmosphere to obtain monomer mixture; A crosslinking agent and a photoinitiator were added to a monomer mixture, stirred until homogeneous, and then irradiated with ultraviolet light to form a prepolymer network. Subsequently, a thermal initiator was added, and the mixture was heated to carry out a thermal polymerization reaction. After the reaction was completed, a polymer solution was obtained. S2. Adhesive preparation: Add tackifying resin, curing agent and antioxidant to polymer solution, stir evenly to obtain the wet tack adhesive.

[0029] In S1, the power of ultraviolet light irradiation is 50W, and the irradiation time is 15min; the temperature of the thermal polymerization reaction is 90℃, and the reaction time is 3h.

[0030] In step S1, before ultraviolet irradiation, the monomer mixture is heated to 60°C and stirred for 1.5 hours.

[0031] The step S2 is followed by a tape forming step: The wet adhesive is applied to a substrate and then dried and cured to obtain a wet adhesive tape. The drying conditions are 100°C for 3 minutes and 40°C for 3 days.

[0032] Example 2: An octyl acrylate-based wet tack adhesive, comprising the following raw materials by weight: 30 kg of octyl acrylate; 3 kg of acrylic acid; 1.5 kg of hydroxyethyl methacrylate; 0.35 kg of cationic monomer; 0.35 kg of active ester crosslinking monomer; Crosslinking agent 0.005 kg; 0.2 kg of photoinitiator; 1.0 kg of thermal initiator; 1.55 kg of tackifying resin; 1.4 kg of curing agent; And 45 kg of solvent; Wherein, the cationic monomer is benzylvinyltrimethylammonium chloride, the active ester crosslinking monomer is N-hydroxysuccinimide acrylate, and the crosslinking agent is N,N-methylenebisacrylamide; The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the thermal initiator is lauroyl peroxide.

[0033] The tackifying resin is an esterified rosin, a terpene phenol resin, and a liquid rosin resin in a mass ratio of 6:7:2.

[0034] The curing agent is an isocyanate curing agent and an epoxy curing agent in a mass ratio of 6:1.

[0035] The solvent is a mixture of deionized water, ethyl acetate and toluene in a volume ratio of 1:8:6.

[0036] Includes the following steps: S1. Preparation of polymer solution: Octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer, active ester crosslinking monomer and solvent are mixed and dissolved under an inert atmosphere to obtain monomer mixture; A crosslinking agent and a photoinitiator were added to a monomer mixture, stirred until homogeneous, and then irradiated with ultraviolet light to form a prepolymer network. Subsequently, a thermal initiator was added, and the mixture was heated to carry out a thermal polymerization reaction. After the reaction was completed, a polymer solution was obtained. S2. Adhesive preparation: Add tackifying resin, curing agent and antioxidant to polymer solution, stir evenly to obtain the wet tack adhesive.

[0037] In S1, the power of ultraviolet light irradiation is 50W, and the irradiation time is 15min; the temperature of the thermal polymerization reaction is 90℃, and the reaction time is 3h.

[0038] In step S1, before ultraviolet irradiation, the monomer mixture is heated to 60°C and stirred for 1.5 hours.

[0039] The step S2 is followed by a tape forming step: The wet adhesive is applied to a substrate and then dried and cured to obtain a wet adhesive tape. The drying conditions are 100°C for 3 minutes and 40°C for 3 days.

[0040] Example 3: An octyl acrylate-based wet tack adhesive, comprising the following raw materials by weight: 25 kg of octyl acrylate; Acrylic acid - 3.5kg; Hydroxyethyl methacrylate 1.0 kg; 0.5 kg of cationic monomer; 0.2 kg of active ester crosslinking monomer; Crosslinking agent 0.006 kg; Photoinitiator 0.15 kg; 1.2 kg of thermal initiator; 1.4 kg of tackifying resin; 1.5 kg of curing agent; And 40 kg of solvent; Wherein, the cationic monomer is benzylvinyltrimethylammonium chloride, the active ester crosslinking monomer is N-hydroxysuccinimide acrylate, and the crosslinking agent is N,N-methylenebisacrylamide; The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the thermal initiator is lauroyl peroxide.

[0041] The tackifying resin is composed of esterified rosin, terpene phenol resin and liquid rosin resin in a mass ratio of 7:6:3.

[0042] The curing agent is an isocyanate curing agent and an epoxy curing agent in a mass ratio of 5:1.

[0043] The solvent is a mixture of deionized water, ethyl acetate and toluene in a volume ratio of 1:9:5.

[0044] Includes the following steps: S1. Preparation of polymer solution: Octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer, active ester crosslinking monomer and solvent are mixed and dissolved under an inert atmosphere to obtain monomer mixture; A crosslinking agent and a photoinitiator were added to a monomer mixture, stirred until homogeneous, and then irradiated with ultraviolet light to form a prepolymer network. Subsequently, a thermal initiator was added, and the mixture was heated to carry out a thermal polymerization reaction. After the reaction was completed, a polymer solution was obtained. S2. Adhesive preparation: Add tackifying resin, curing agent and antioxidant to polymer solution, stir evenly to obtain the wet tack adhesive.

[0045] In S1, the power of ultraviolet light irradiation is 50W, and the irradiation time is 15min; the temperature of the thermal polymerization reaction is 90℃, and the reaction time is 3h.

[0046] In step S1, before ultraviolet irradiation, the monomer mixture is heated to 60°C and stirred for 1.5 hours.

[0047] The step S2 is followed by a tape forming step: The wet adhesive is applied to a substrate and then dried and cured to obtain a wet adhesive tape. The drying conditions are 100°C for 3 minutes and 40°C for 3 days.

[0048] The following comparison model was also set: Comparative Example 1: Based on Example 2, the difference is that the cationic monomer (benzylvinyltrimethylammonium chloride) was completely removed, and the rest was the same as Example 2.

[0049] Comparative Example 2: Based on Example 2, the difference is that the active ester crosslinking monomer (N-hydroxysuccinimide acrylate) was completely removed, and the isocyanate / epoxy curing agent added later was also removed accordingly. The rest is the same as Example 2.

[0050] Comparative Example 3: Based on Example 2, the difference is that the photoinitiator and photocuring steps are removed, and the N,N-methylenebisacrylamide crosslinking agent is added together with the thermal initiator during the thermal polymerization stage. The rest is the same as in Example 2.

[0051] Comparative Example 4: Based on Example 2, the difference is that the esterified rosin, terpene phenol resin, and liquid rosin are replaced with an equal amount of single terpene resin, and the rest is the same as in Example 2.

[0052] Comparative Example 5: A classic acrylic pressure-sensitive adhesive formulation was used. Only octyl acrylate (40 kg) and acrylic acid (5 kg) were used as comonomers, with the same amount of tackifying resin (15 kg) and thermal initiator (1 kg) added for thermal polymerization. It did not contain cationic monomers (benzylvinyltrimethylammonium chloride), reactive ester crosslinking monomers (N-hydroxysuccinimide acrylate), photoinitiators, or a photocuring step.

[0053] Performance Testing: The viscosity of this invention was tested according to GB-T 2794-2022 Determination of Viscosity of Adhesives; the 180° peel strength of this invention was tested according to GB-T2792-2014 Test Method for Peel Strength of Adhesive Tapes; the initial tack of this invention was tested using the rolling ball method according to GB-T 4852-84 Test Method for Initial Tack of Pressure-Sensitive Adhesive Tapes; the resistance to damp heat aging of this invention was tested according to GB / T 15905-1995 Test Method for Damp Heat Aging of Vulcanized Rubber; the mass or volume change rate of the cured adhesive film was measured after immersing it in deionized water at 37°C for 72 hours; the results are shown below: Table 1. Performance Tests of Wet-Tack Adhesives

[0054] Data Analysis: Examples 1-3 of this invention are significantly superior to the comparative examples and classic formulations in terms of wet adhesion, crosslinking stability and overall performance, demonstrating clear technical advantages.

[0055] Regarding wet adhesion performance, the wet 180° peel strength of all examples reached 8.65-8.85 N / 25 mm, with Example 2 showing the best at 8.85 N / 25 mm. In contrast, Comparative Example 1 (without cationic monomer) only achieved 5.03 N / 25 mm, and Comparative Example 5 (classic formulation) only 3.78 N / 25 mm, showing a significant difference. In terms of initial tack, Example 2 achieved a ball size of 9, far exceeding the 4 of Comparative Example 5, confirming that the electrostatic adsorption of the cationic monomer can effectively overcome the water film barrier, solving the core problem of wet adhesion decay in existing technologies.

[0056] Regarding crosslinking and stability, Example 2 showed a 91% retention rate during humid heat aging and a mass change rate of only 2.8% after immersion in water at 37°C for 72 hours; Comparative Example 2 (without active ester crosslinking monomers and curing agents) showed a 62% retention rate and a mass change rate of 8.5%; and Comparative Example 3 (without UV curing) showed a 78% retention rate and a mass change rate of 5.7%. This indicates that the synergistic effect of UV-thermal stepwise polymerization and the dual crosslinking system constructs a dense and stable three-dimensional network, significantly improving water resistance and anti-aging ability.

[0057] In terms of overall performance balance, Example 2, with a viscosity of 6800 mPa·s, is well-suited to the coating process, and its dry / wet peel strength and initial tack are both within the optimal range. Comparative Example 4 (single tackifying resin) shows a decline in all performance aspects, while Comparative Example 5, with its classic formulation, lags behind in all aspects. This demonstrates that the present invention achieves a multi-dimensional balance of "viscosity-cohesion-stability" through monomer synergy, process optimization, and the formulation of mixed tackifying resins, proving the scientific effectiveness of the technical solution.

[0058] 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. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An octyl acrylate-based wet-adhesive adhesive, characterized in that, Raw materials comprising the following parts by weight: 25-35 parts of octyl acrylate; Acrylic acid 2.5-3.5 parts; Hydroxyethyl methacrylate, 1.0-2.0 parts; 0.2-0.5 parts of cationic monomer; 0.2-0.5 parts of active ester crosslinking monomer; Crosslinking agent 0.004-0.006 parts; Photoinitiator 0.15-0.25 parts; 0.8-1.2 parts of thermal initiator; 1.4-1.7 parts of tackifying resin; 1.3-1.5 parts of curing agent; And 40-50 parts of solvent; Wherein, the cationic monomer is benzylvinyltrimethylammonium chloride, the active ester crosslinking monomer is N-hydroxysuccinimide acrylate, and the crosslinking agent is N,N-methylenebisacrylamide; The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the thermal initiator is lauroyl peroxide.

2. The octyl acrylate wet-adhesive adhesive according to claim 1, characterized in that, The molar ratio of octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer and active ester crosslinking monomer is 100-120:25-30:7-9:0.8-1.2:0.9-1.

3.

3. The octyl acrylate wet-adhesive adhesive according to claim 1, characterized in that, The tackifying resin is an esterified rosin, terpene phenol resin and liquid rosin resin in a mass ratio of 5-7:6-8:1-3.

4. The octyl acrylate wet-adhesive adhesive according to claim 1, characterized in that, The curing agent is an isocyanate curing agent and an epoxy curing agent with a mass ratio of 5-7:

1.

5. The octyl acrylate wet-adhesive adhesive according to claim 1, characterized in that, The solvent is a mixture of deionized water, ethyl acetate and toluene in a volume ratio of 1:7-9:5-7.

6. A method for preparing an octyl acrylate wet-adhesive adhesive as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of polymer solution: Octyl acrylate, acrylic acid, hydroxyethyl methacrylate, cationic monomer, active ester crosslinking monomer and solvent are mixed and dissolved under an inert atmosphere to obtain monomer mixture; A crosslinking agent and a photoinitiator were added to a monomer mixture, stirred until homogeneous, and then irradiated with ultraviolet light to form a prepolymer network. Subsequently, a thermal initiator was added, and the mixture was heated to carry out a thermal polymerization reaction. After the reaction was completed, a polymer solution was obtained. S2. Adhesive preparation: Add tackifying resin, curing agent and antioxidant to polymer solution, stir evenly to obtain the wet tack adhesive.

7. The method for preparing the octyl acrylate wet tack adhesive according to claim 6, characterized in that, In step S1, the power of ultraviolet light irradiation is 40-60W, and the irradiation time is 10-20min; the temperature of the thermal polymerization reaction is 85-95℃, and the reaction time is 2-4h.

8. The method for preparing the octyl acrylate wet tack adhesive according to claim 6, characterized in that, In step S1, before ultraviolet irradiation, the monomer mixture is heated to 55-65°C and stirred for 1-2 hours.

9. The method for preparing the octyl acrylate wet tack adhesive according to claim 6, characterized in that, The step S2 is followed by a tape forming step: The wet adhesive is applied to a substrate and then dried and cured to obtain a wet adhesive tape. The drying conditions are 90-110℃ for 2-5 minutes and the curing conditions are 35-45℃ for 2-4 days.

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