A weather-resistant and mildew-resistant MS adhesive and its preparation process

Abstract

This invention relates to the field of adhesive preparation technology, specifically to a weather-resistant and mildew-resistant MS adhesive and its preparation process. The process includes the following steps: preparing an antibacterial silane-terminated polyurethane resin, preparing a bio-based UV absorber, preparing light-stabilized capsules, and preparing the weather-resistant and mildew-resistant MS adhesive. This invention combines caffeic acid and ethylene carbonate to prepare a bio-based UV absorber. After fabricating polyester-silane hybrid microcapsules using the bio-based UV absorber as the core material, moisture-responsive slow release is achieved. Even if the wall material is completely degraded, the released BHBPE remains a solid polymer, not volatilizing, precipitating, or being lost due to diffusion within the sealant matrix. Finally, it is applied to silane-terminated polyurethane MS adhesive, providing both durable UV absorption and long-lasting antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of adhesive preparation technology, specifically to a weather-resistant and mildew-resistant MS adhesive and its preparation process. Background Technology

[0002] Weather-resistant and mildew-resistant MS sealant is an important functional material used in building joints, pipe penetrations, and other areas. It needs to prevent the spread of flames and smoke in the event of a fire, while also withstanding structural displacement and deformation during daily use. With increasingly stringent building safety standards, higher requirements are being placed on the service life of weather-resistant and mildew-resistant MS sealant. The demand for outdoor and semi-outdoor applications is growing, requiring sealants that not only possess fire resistance and elasticity but also excellent weather resistance and antibacterial and mildew-resistant properties.

[0003] Currently, the main way to impart antibacterial properties to sealants is through physical blending of organic antifungal agents or inorganic antibacterial agents, such as isothiazolinones and nano-silver. These low-molecular-weight antibacterial agents are easily lost from the sealant during use through migration, volatilization, or water extraction, resulting in a limited antibacterial lifespan. During long-term outdoor use, continuous ultraviolet radiation causes photo-oxidative degradation of the sealant matrix resin, leading to molecular chain breakage and cross-linking network destruction. This results in the sealant gradually exhibiting powdering, cracking, and loss of elasticity, not only degrading its mechanical properties but also further accelerating the loss of antibacterial agents. When microcracks appear on the sealant surface due to aging, mold spores can more easily attach and colonize. The organic acids and enzymes produced by microbial metabolism further erode the sealant surface, creating a vicious cycle.

[0004] In terms of weather protection, the conventional approach is to add UV absorbers and hindered amine light stabilizers. UV absorbers, such as benzotriazoles and benzophenones, are mostly small-molecule organic compounds, which also face migration and exudation problems. They are significantly lost under high temperature or solvent contact conditions, making it difficult to provide long-term UV protection matching the sealant's design life. In recent years, microencapsulation technology has been attempted to encapsulate weather-resistant additives to delay release. However, existing microencapsulation wall materials are mostly melamine-formaldehyde resins or polyurea, with release mechanisms primarily based on passive diffusion or mechanical rupture. This makes it difficult to respond synchronously with the sealant's moisture curing process, resulting in defects such as excessively rapid or incomplete release.

[0005] Furthermore, when antibacterial agents and weather-resistant additives are added simultaneously to the same formulation, mutual interference may occur between different functional components: some organic antifungal agents containing thiol or amine groups may consume the active free radicals of hindered amine light stabilizers, weakening the light stabilizing effect; the photocatalytic activity of inorganic antibacterial agents may accelerate the photo-oxidative degradation of the resin matrix itself. Therefore, how to achieve efficient synergy of multiple functions such as antibacterial, weather-resistant, fire-retardant, and flexible properties in a single sealant system, while ensuring the long-term effectiveness of each function in long-term outdoor service, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a weather-resistant and mildew-resistant MS adhesive and its preparation process.

[0007] A preparation process for a weather-resistant and mildew-resistant MS adhesive specifically includes the following steps: S1: Preparation of antibacterial silane-terminated polyurethane resin Polyether diol and polyester diol were mixed, vacuum dehydrated, then cooled, and then isophorone diisocyanate and organic bismuth catalyst were added. The mixture was reacted for a period of time under nitrogen protection to obtain a prepolymer. Trimethoxysilylpropyl dimethyl octadecyl ammonium chloride and dibutyltin dilaurate were added to the prepolymer, and the mixture was cooled again. Aminosilane was added dropwise and the mixture was kept at the temperature to obtain an antibacterial silane-terminated polyurethane resin. S2: Preparation of bio-based ultraviolet absorbers In a three-necked flask equipped with a condenser and a nitrogen inlet, caffeic acid, ethylene carbonate, and TBAB were added. Nitrogen gas was introduced for protection, and the mixture was stirred and heated to maintain the reaction temperature. Heating was then stopped, and after cooling, deionized water was added. The mixture was heated, stirred, and washed. The liquid was filtered off while hot, and the solid product was washed and dried to obtain the DHE-CA monomer. In a reaction flask, the DHE-CA monomer and immobilized lipase Novozym435 were added. The system was sealed, evacuated, heated, and magnetically stirred. Finally, anhydrous ethanol was added, stirred, and the enzyme was recovered by filtration. The resulting liquid product was dried under vacuum after removing the ethanol using a rotary evaporator to obtain a bio-based ultraviolet absorber. S3: Preparation of light-stabilized capsules Bio-based UV absorber and hindered amine light stabilizer GW-622 were dissolved in anhydrous ethanol, and IPTS, HDI and TEOS were added. The mixture was stirred to dissolve and obtain an oil phase. An emulsifier was added to deionized water, followed by the oil phase prepared above. The mixture was emulsified by high-speed shearing to obtain an emulsion. The emulsion was stirred at room temperature, and then n-butanol was added. The mixture was stirred and reacted. The solid product was separated by centrifugation, washed, and vacuum dried to obtain light-stabilized microcapsules. S4: Preparation of weather-resistant and mildew-resistant MS adhesive Antibacterial silane-terminated polyurethane resin, PPG plasticizer, and vinyltrimethoxysilane dehydrating agent were added to a dual planetary mixer and stirred. Nano-calcium carbonate and heavy calcium carbonate were added and dispersed under vacuum conditions. Then, complex coupling agent, thixotropic agent, and light-stabilized microcapsules were added and stirred. Finally, dibutyltin dilaurate catalyst was added and stirred. After discharge, weather-resistant and mildew-resistant MS adhesive was obtained.

[0008] Further, step S1 prepares an antibacterial silane-terminated polyurethane resin, including the following steps: Mix 75-80 parts by weight of polyether diol and 17-25 parts by weight of polyester diol, and dehydrate under vacuum at 110-120°C for 2-2.5 hours. Then cool to 70-80°C, add 42-52 parts by weight of isophorone diisocyanate and 0.05-0.15 parts by weight of organic bismuth catalyst, and react at 70-75°C for 2-3 hours under nitrogen protection to obtain a prepolymer. Add 6-12 parts by weight of trimethoxysilylpropyl dimethyloctadecyl ammonium chloride and 0.1-0.2 parts by weight of dibutyltin dilaurate to the prepolymer, and react at 75-80°C for 1.5 hours. Then cool to 65-70°C, add 25-32 parts by weight of aminosilane dropwise, and keep the reaction at this temperature for 1-1.5 hours to perform silane end-capping to obtain an antibacterial silane-capped polyurethane resin.

[0009] Further, step S2 prepares a bio-based ultraviolet absorber, including the following steps: In a three-necked flask equipped with a condenser and a nitrogen port, add 42-48 parts by weight of caffeic acid, 45-50 parts by weight of ethylene carbonate and 3-4 parts by weight of TBAB, purge with nitrogen for protection, stir and heat to 120-130°C, maintain the temperature for 4-6 hours, then stop heating, cool and add 50-80 parts by weight of deionized water, heat to 60-65°C and stir to wash, filter out the liquid while hot, wash the solid product twice, and dry under vacuum at 60-70°C for 24-26 hours to obtain the DHE-CA monomer; Add 100 parts by mass of DHE-CA monomer and 8-12 parts by mass of immobilized lipase Novozym435 to a reaction flask, seal the system, slowly evacuate to 30-50 mbar using a vacuum pump, and simultaneously raise the temperature to 73-78℃. Stir magnetically at 100-150 r / min for 18-24 hours. Finally, add 30-40 parts by mass of anhydrous ethanol and stir at 40-45℃ for 10-20 minutes. Filter the mixture through a nylon filter cloth to recover the enzyme. Remove the ethanol from the resulting liquid product using a rotary evaporator and then vacuum dry at 50-60℃ to obtain a bio-based ultraviolet absorber.

[0010] Further, step S3 involves preparing the photostable capsule, including the following steps: Dissolve 5-7 parts by weight of bio-based UV absorber and 5-7 parts by weight of hindered amine light stabilizer GW-622 in 15-20 parts by weight of anhydrous ethanol, add 1-2 parts by weight of IPTS, 0.5-1 parts by weight of HDI and 5-7 parts by weight of TEOS, and stir to dissolve to obtain the oil phase. Add 0.1-0.2 parts by weight of emulsifier to 40-50 parts by weight of deionized water, then add the oil phase prepared above, and emulsify at high speed of 10000-15000 r / min for 10-20 minutes to obtain an emulsion. Stir the emulsion at room temperature (22-24℃) for 15-30 minutes, then add 1-2 parts by weight of n-butanol, adjust the pH to 8.0-8.5 with ammonia water, stir and react at 40-50℃ for 4-8 hours, centrifuge to separate the solid product, wash with water and ethanol alternately 3 times, and vacuum dry at 40-45℃ for 24-26 hours to obtain photostable microcapsules.

[0011] Further, step S4 prepares the weather-resistant and mildew-resistant MS adhesive, including the following steps: In a double planetary mixer, add 100-110 parts by weight of antibacterial silane-terminated polyurethane resin, 30 parts by weight of PPG plasticizer, and 2-3 parts by weight of vinyltrimethoxysilane dehydrating agent. Mix under vacuum ≤−0.09MPa and 200-400 r / min for 15-20 minutes. Add 50-60 parts by weight of nano-calcium carbonate and 20-30 parts by weight of heavy calcium carbonate in two batches, and disperse under vacuum at 800-1200 r / min. The material temperature is controlled below 40℃, and the dispersion time is 30-40 minutes. Then, 3-4 parts by weight of compound coupling agent, 1-2 parts by weight of thixotropic agent and 5-7 parts by weight of light-stabilized microcapsules are added in sequence. Stir at 400-600 r / min under vacuum for 20-30 minutes. Finally, 0.4-0.6 parts by weight of dibutyltin dilaurate catalyst are added, and the mixture is stirred at low speed at 200-300 r / min under vacuum for 10-15 minutes. After discharge, weather-resistant and mildew-resistant MS adhesive is obtained.

[0012] Furthermore, the polyether diol is specifically polytetrahydrofuran ether diol, and the polyester diol is specifically polycaprolactone diol.

[0013] Furthermore, the emulsifier is specifically sodium dodecyl sulfate.

[0014] Furthermore, the compounding agent is specifically prepared by compounding KH-560 and KH-792 in a 1:1 mass ratio.

[0015] Furthermore, the thixotropic agent is specifically a polyamide wax.

[0016] A weather-resistant and mildew-resistant MS adhesive is prepared by the above-mentioned preparation process of weather-resistant and mildew-resistant MS adhesive.

[0017] The present invention has the following advantages: 1. This invention combines caffeic acid and ethylene carbonate to prepare a bio-based UV absorber. The caffeic acid molecule contains one carboxyl group and two phenolic hydroxyl groups, possessing the potential to be an AB2-type hyperbranched polymer monomer in terms of the number of functional groups. Through the action of ethylene carbonate, the two phenolic hydroxyl groups are quantitatively converted into aliphatic primary alcohols. The converted product has one carboxyl group and two primary hydroxyl groups with matching reactivity, making it a strictly AB2-type monomer. Simultaneously, this conversion completely preserves the groups that enable caffeic acid to absorb UV light, thus inheriting its strong UV absorption capacity. Under the catalysis of immobilized lipase, the DHE-CA monomer undergoes bulk polycondensation to obtain the bio-based UV absorber. The polymer molecule size is much larger than that of traditional small-molecule UV absorbers, fundamentally eliminating the possibility of migration and leakage. After fabricating polyester-silane hybrid microcapsules using the bio-based UV absorber as the core material, moisture-responsive slow release can be achieved. Even if the wall material is completely degraded, the released BHBPE remains a solid polymer, not volatilizing, precipitating, or being lost due to diffusion within the sealant matrix. Ultimately, it is applied to silane-terminated polyurethane MS adhesive, providing both long-lasting UV absorption and long-lasting antibacterial properties.

[0018] 2. This invention separates antibacterial and weather-resistant functions onto different carriers, ensuring they do not interfere with each other and work synergistically. The antibacterial function is covalently anchored to the resin backbone. The silane end groups of the quaternary ammonium salt participate in polycondensation during resin synthesis, making the bactericidal groups part of the cross-linked network, achieving non-migratory and long-lasting antibacterial properties. The weather-resistant function is encapsulated within microcapsules: a bio-based hyperbranched polyester UV absorber and a hindered amine light stabilizer are used as the core material, and a polyester-silane hybrid structure serves as the wall material. The alkoxysilane bonds on the wall material hydrolyze simultaneously during the moisture curing of the MS adhesive, changing from dense to porous, gradually releasing the UV absorber and free radical scavenger. This achieves the effect of light-stabilized microcapsules protecting the resin skeleton from UV degradation, maintaining the integrity of the quaternary ammonium salt-anchored polymer network, and preventing the antibacterial function from diminishing due to matrix aging; the antibacterial resin surface inhibits mold colonization and biofilm formation, preventing microbial metabolites from corroding the colloidal surface and microcapsule wall material, thus extending the effective service life of the microcapsules. Ultimately, this achieves the synergistic and continuous long-lasting effects of both weather resistance and antibacterial properties in MS adhesive. Attached Figure Description

[0019] Figure 1 This is a flow chart of the preparation process of the weather-resistant and mildew-resistant MS adhesive of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention. Example 1

[0021] A preparation process for a weather-resistant and mildew-resistant MS adhesive, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of antibacterial silane-terminated polyurethane resin 75 parts by mass of polytetrahydrofuran ether diol and 17 parts by mass of polycaprolactone diol were mixed and vacuum dehydrated at 110°C for 2 hours. The mixture was then cooled to 70°C, and 42 parts by mass of isophorone diisocyanate and 0.05 parts by mass of organic bismuth catalyst were added. The mixture was reacted at 70°C for 2 hours under nitrogen protection to obtain a prepolymer. 6 parts by mass of trimethoxysilylpropyl dimethyloctadecyl ammonium chloride and 0.1 parts by mass of dibutyltin dilaurate were added to the prepolymer. The mixture was reacted at 75°C for 1.5 hours, then cooled to 65°C, and 25 parts by mass of aminosilane were added dropwise. The mixture was kept at this temperature for 1 hour to achieve silane end-capping, resulting in an antibacterial silane-capped polyurethane resin.

[0022] S2: Preparation of bio-based ultraviolet absorbers In a three-necked flask equipped with a condenser and a nitrogen port, 42 parts by mass of caffeic acid, 45 parts by mass of ethylene carbonate and 3 parts by mass of TBAB were added. Nitrogen gas was introduced for protection, and the mixture was stirred and heated to 120°C. The reaction was maintained at this temperature for 4 hours. Heating was then stopped, and the mixture was cooled. 50 parts by mass of deionized water were added, and the mixture was heated to 60°C and stirred for washing. The liquid was filtered off while hot, and the solid product was washed twice. The product was then dried under vacuum at 60°C for 24 hours to obtain the DHE-CA monomer. 100 parts by mass of DHE-CA monomer and 8 parts by mass of immobilized lipase Novozym435 were added to a reaction flask, the system was sealed, and a vacuum pump was used to slowly evacuate to 30 mbar while the temperature was raised to 73°C. The mixture was magnetically stirred at 100 r / min for 18 hours. Finally, 30 parts by mass of anhydrous ethanol were added, and the mixture was stirred at 40°C for 10 minutes. The enzyme was recovered by filtration through a nylon filter cloth. The resulting liquid product was dried under vacuum at 50°C after removing the ethanol using a rotary evaporator to obtain a bio-based ultraviolet absorber.

[0023] S3: Preparation of light-stabilized capsules Dissolve 5 parts by weight of bio-based UV absorber and 5 parts by weight of hindered amine light stabilizer GW-622 in 15 parts by weight of anhydrous ethanol, add 1 part by weight of IPTS, 0.5 parts by weight of HDI and 5 parts by weight of TEOS, stir to dissolve and obtain oil phase; Add 0.1 parts by mass of sodium dodecyl sulfate emulsifier to 40 parts by mass of deionized water, then add the oil phase prepared above, and emulsify at high speed of 10000 r / min for 10 minutes to obtain an emulsion. Stir the emulsion at room temperature (22°C) for 15 minutes, then add 1 part by mass of n-butanol, adjust the pH to 8.0 with ammonia water, stir and react at 40°C for 4 hours, centrifuge to separate the solid product, wash with water and ethanol alternately 3 times, and vacuum dry at 40°C for 24 hours to obtain photostable microcapsules.

[0024] S4: Preparation of weather-resistant and mildew-resistant MS adhesive In a double planetary mixer, 100 parts by mass of antibacterial silane-terminated polyurethane resin, 30 parts by mass of PPG plasticizer, and 2 parts by mass of vinyltrimethoxysilane dehydrating agent were added and mixed at 200 r / min under vacuum ≤−0.09 MPa for 15 minutes. Then, 50 parts by mass of nano-calcium carbonate and 20 parts by mass of heavy calcium carbonate were added in two batches and dispersed at 800 r / min under vacuum, with the material temperature controlled below 40℃ for 30 minutes. Next, 3 parts by mass of complex coupling agent, 1 part by mass of thixotropic polyamide wax, and 5 parts by mass of light-stabilized microcapsules were added sequentially and stirred at 400 r / min under vacuum for 20 minutes. Finally, 0.4 parts by mass of dibutyltin dilaurate catalyst were added and stirred at low speed at 200 r / min under vacuum for 10 minutes. After discharge, weather-resistant and mildew-resistant MS adhesive was obtained. The complex coupling agent was specifically prepared by compounding KH-560 and KH-792 in a 1:1 mass ratio. Example 2

[0025] A preparation process for a weather-resistant and mildew-resistant MS adhesive, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of antibacterial silane-terminated polyurethane resin 80 parts by mass of polytetrahydrofuran ether diol and 25 parts by mass of polycaprolactone diol were mixed and vacuum dehydrated at 120°C for 2.5 hours. The mixture was then cooled to 80°C, and 52 parts by mass of isophorone diisocyanate and 0.15 parts by mass of organic bismuth catalyst were added. The mixture was reacted at 75°C for 3 hours under nitrogen protection to obtain a prepolymer. 12 parts by mass of trimethoxysilylpropyl dimethyloctadecyl ammonium chloride and 0.2 parts by mass of dibutyltin dilaurate were added to the prepolymer. The mixture was reacted at 80°C for 1.5 hours, then cooled to 70°C, and 32 parts by mass of aminosilane were added dropwise. The mixture was kept at this temperature for 1.5 hours to achieve silane end-capping, resulting in an antibacterial silane-capped polyurethane resin.

[0026] S2: Preparation of bio-based ultraviolet absorbers In a three-necked flask equipped with a condenser and a nitrogen port, 48 parts by mass of caffeic acid, 50 parts by mass of ethylene carbonate and 4 parts by mass of TBAB were added. Nitrogen gas was introduced for protection, and the mixture was stirred and heated to 130°C. The reaction was maintained at this temperature for 6 hours. Heating was then stopped, and the mixture was cooled. 80 parts by mass of deionized water were added, and the mixture was heated to 65°C and stirred for washing. The liquid was filtered off while hot, and the solid product was washed twice. The product was then dried under vacuum at 70°C for 26 hours to obtain the DHE-CA monomer. 100 parts by mass of DHE-CA monomer and 12 parts by mass of immobilized lipase Novozym435 were added to a reaction flask, the system was sealed, and a vacuum pump was used to slowly evacuate to 50 mbar while the temperature was raised to 78°C. The mixture was magnetically stirred at 150 r / min for 24 hours. Finally, 40 parts by mass of anhydrous ethanol were added, and the mixture was stirred at 45°C for 20 minutes. The enzyme was recovered by filtration through a nylon filter cloth. The resulting liquid product was dried under vacuum at 60°C after removing the ethanol using a rotary evaporator to obtain a bio-based ultraviolet absorber.

[0027] S3: Preparation of light-stabilized capsules Dissolve 6 parts by weight of bio-based UV absorber and 6 parts by weight of hindered amine light stabilizer GW-622 in 18 parts by weight of anhydrous ethanol, add 1.5 parts by weight of IPTS, 0.8 parts by weight of HDI and 6 parts by weight of TEOS, and stir to dissolve to obtain the oil phase; Add 0.15 parts by mass of sodium dodecyl sulfate emulsifier to 45 parts by mass of deionized water, then add the oil phase prepared above, and emulsify at high speed of 12000 r / min for 15 minutes to obtain an emulsion. Stir the emulsion at room temperature (23°C) for 18 minutes, then add 1.5 parts by mass of n-butanol, adjust the pH to 8.3 with ammonia water, stir the reaction at 45°C for 6 hours, centrifuge to separate the solid product, wash with water and ethanol alternately 3 times, and vacuum dry at 42°C for 25 hours to obtain photostable microcapsules.

[0028] S4: Preparation of weather-resistant and mildew-resistant MS adhesive In a dual planetary mixer, 105 parts by mass of antibacterial silane-terminated polyurethane resin, 30 parts by mass of PPG plasticizer, and 2.5 parts by mass of vinyltrimethoxysilane dehydrating agent were added and mixed at 400 r / min under vacuum ≤−0.09 MPa for 18 minutes. Then, 55 parts by mass of nano-calcium carbonate and 25 parts by mass of heavy calcium carbonate were added in two batches and dispersed at 1000 r / min under vacuum, with the material temperature controlled below 40℃ for 35 minutes. Next, 3.5 parts by mass of complex coupling agent, 1.5 parts by mass of thixotropic polyamide wax, and 6 parts by mass of light-stabilized microcapsules were added sequentially and stirred at 500 r / min under vacuum for 25 minutes. Finally, 0.5 parts by mass of dibutyltin dilaurate catalyst were added and stirred at low speed at 250 r / min under vacuum for 12 minutes. After discharge, weather-resistant and mildew-resistant MS adhesive was obtained. The complex coupling agent was specifically prepared by compounding KH-560 and KH-792 in a 1:1 mass ratio. Example 3

[0029] A preparation process for a weather-resistant and mildew-resistant MS adhesive, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of antibacterial silane-terminated polyurethane resin 80 parts by mass of polytetrahydrofuran ether diol and 25 parts by mass of polycaprolactone diol were mixed and vacuum dehydrated at 120°C for 2.5 hours. The mixture was then cooled to 80°C, and 52 parts by mass of isophorone diisocyanate and 0.15 parts by mass of organic bismuth catalyst were added. The mixture was reacted at 75°C for 3 hours under nitrogen protection to obtain a prepolymer. 12 parts by mass of trimethoxysilylpropyl dimethyloctadecyl ammonium chloride and 0.2 parts by mass of dibutyltin dilaurate were added to the prepolymer. The mixture was reacted at 80°C for 1.5 hours, then cooled to 70°C, and 32 parts by mass of aminosilane were added dropwise. The mixture was kept at this temperature for 1.5 hours to achieve silane end-capping, resulting in an antibacterial silane-capped polyurethane resin.

[0030] S2: Preparation of bio-based ultraviolet absorbers In a three-necked flask equipped with a condenser and a nitrogen port, 48 parts by mass of caffeic acid, 50 parts by mass of ethylene carbonate and 4 parts by mass of TBAB were added. Nitrogen gas was introduced for protection, and the mixture was stirred and heated to 130°C. The reaction was maintained at this temperature for 6 hours. Heating was then stopped, and the mixture was cooled. 80 parts by mass of deionized water were added, and the mixture was heated to 65°C and stirred for washing. The liquid was filtered off while hot, and the solid product was washed twice. The product was then dried under vacuum at 70°C for 26 hours to obtain the DHE-CA monomer. 100 parts by mass of DHE-CA monomer and 12 parts by mass of immobilized lipase Novozym435 were added to a reaction flask, the system was sealed, and a vacuum pump was used to slowly evacuate to 50 mbar while the temperature was raised to 78°C. The mixture was magnetically stirred at 150 r / min for 24 hours. Finally, 40 parts by mass of anhydrous ethanol were added, and the mixture was stirred at 45°C for 20 minutes. The enzyme was recovered by filtration through a nylon filter cloth. The resulting liquid product was dried under vacuum at 60°C after removing the ethanol using a rotary evaporator to obtain a bio-based ultraviolet absorber.

[0031] S3: Preparation of light-stabilized capsules Dissolve 7 parts by weight of bio-based UV absorber and 7 parts by weight of hindered amine light stabilizer GW-622 in 20 parts by weight of anhydrous ethanol, add 2 parts by weight of IPTS, 1 part by weight of HDI and 7 parts by weight of TEOS, stir to dissolve and obtain oil phase; Add 0.2 parts by mass of sodium dodecyl sulfate emulsifier to 50 parts by mass of deionized water, then add the oil phase prepared above, and emulsify at high speed of 15000 r / min for 20 minutes to obtain an emulsion. Stir the emulsion at room temperature (24℃) for 30 minutes, then add 2 parts by mass of n-butanol, adjust the pH to 8.5 with ammonia water, stir and react at 50℃ for 8 hours, centrifuge to separate the solid product, wash with water and ethanol alternately 3 times, and vacuum dry at 45℃ for 26 hours to obtain photostable microcapsules.

[0032] S4: Preparation of weather-resistant and mildew-resistant MS adhesive In a double planetary mixer, 110 parts by mass of antibacterial silane-terminated polyurethane resin, 30 parts by mass of PPG plasticizer, and 3 parts by mass of vinyltrimethoxysilane dehydrating agent were added and mixed at 400 r / min under vacuum ≤−0.09 MPa for 20 minutes. Then, 60 parts by mass of nano-calcium carbonate and 30 parts by mass of heavy calcium carbonate were added in two batches and dispersed at 1200 r / min under vacuum, with the material temperature controlled below 40℃ for 40 minutes. Next, 4 parts by mass of complex coupling agent, 2 parts by mass of thixotropic polyamide wax, and 7 parts by mass of light-stabilized microcapsules were added sequentially and stirred at 600 r / min under vacuum for 30 minutes. Finally, 0.6 parts by mass of dibutyltin dilaurate catalyst were added and stirred at low speed at 300 r / min under vacuum for 15 minutes. After discharge, weather-resistant and mildew-resistant MS adhesive was obtained. The complex coupling agent was specifically prepared by compounding KH-560 and KH-792 in a 1:1 mass ratio.

[0033] Comparative Example 1: Compared with Example 1, the difference of Comparative Example 1 is that caffeic acid is not added in step S2, but ethylene carbonate of equal mass is used to replace caffeic acid. The other steps remain unchanged, and it is referred to as Comparative Example 1.

[0034] Comparative Example 2: Compared with Example 1, Comparative Example 2 differs in that ethylene carbonate is not added in step S2, but is replaced by an equal mass of caffeic acid. The remaining steps remain unchanged, and it is referred to as Comparative Example 2.

[0035] Comparative Example 3: Compared with Example 1, the difference of Comparative Example 3 is that the bio-based UV absorber prepared in step S2 is not added in step S3, but the bio-based UV absorber is replaced with an equal mass of UV absorber UV-326. The other steps remain unchanged, and it is referred to as Comparative Example 3.

[0036] Samples of Examples 1-3 and Comparative Examples 1-3 were prepared into 20*20cm samples. Each sample was first inoculated with mold spores and cultured at 28℃ and 90%RH for 28 days, followed by 1000 hours of QUV aging. The surface mold spot grade was evaluated using the method recorded in GB / T 1741-2020 "Determination of Antifungal Resistance of Paint Films", as shown in Table 1.

[0037]

[0038] Examples 1-3 have the best anti-mold rating, which is level 0. This is due to the synergy between the quaternary ammonium salt antibacterial resin and the light-stabilized microcapsules. The antibacterial surface inhibits mold colonization, while the light stabilizer protects the resin skeleton from UV degradation and maintains the integrity of the antibacterial anchoring network.

[0039] Comparative Examples 1 and 2 could not obtain effective UV absorbers. The lack of caffeic acid resulted in the absence of a UV chromophore core. The lack of ethylene carbonate prevented the conversion of phenolic hydroxyl groups into polycondensable primary alcohols, thus preventing the formation of hyperbranched structures. UV aging led to severe degradation of the resin matrix, and the loss of quaternary ammonium salts along with network breakage, resulting in the near loss of antifungal properties.

[0040] Comparative Example 3 uses UV-326 instead of bio-based UV absorber. Although it has UV absorption function, the small molecules gradually migrate and seep out during the aging process, resulting in a decrease in protective effect. Furthermore, it is lost more quickly in the bacterial environment, and its anti-mildew performance is inferior to that of Example 3.

[0041] Examples 1-3 and Comparative Examples 1-3 were prepared into 20*20cm samples and subjected to 1000 hours of QUV accelerated aging using the method in GB / T 16422.3-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent Ultraviolet Lamps". The tensile strength and elongation at break of each group of samples before and after aging were tested using the method in GB / T 14683-201 "Silicone and Modified Silicone Building Sealants". The results are shown in Table 2.

[0042]

[0043] Examples 1-3 show the best mechanical retention rate, with the bio-based UV absorber exhibiting macromolecular non-migration, moisture-responsive microcapsule release providing full-process UV protection, and the resin network protected from photo-oxidative chain breakage.

[0044] In Comparative Examples 1 and 2, the lack of key raw materials prevented the effective synthesis of the UV absorber. Specifically, Comparative Example 1 lacked caffeic acid, thus missing the UV chromophore core; Comparative Example 2 lacked ethylene carbonate, and the phenolic hydroxyl groups were not converted to primary alcohols, preventing the formation of a hyperbranched structure through polycondensation. Both groups experienced rapid resin degradation under long-term UV irradiation, with mechanical retention rates below 51%.

[0045] Comparative Example 3 replaced the bio-based UV absorber with UV-326. It was effective in the initial UV absorption, but the small molecules gradually volatilized and migrated during aging. After 1000 hours, the protective effect was significantly different from that of Example 3, and the strength retention rate was about 12 percentage points lower.

[0046] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A preparation process for a weather-resistant and mildew-resistant MS adhesive, characterized in that, Specifically, the following steps are included: S1: Preparation of antibacterial silane-terminated polyurethane resin Polyether diol and polyester diol were mixed, vacuum dehydrated, then cooled, and then isophorone diisocyanate and organic bismuth catalyst were added. The mixture was reacted for a period of time under nitrogen protection to obtain a prepolymer. Trimethoxysilylpropyl dimethyl octadecyl ammonium chloride and dibutyltin dilaurate were added to the prepolymer, and the mixture was cooled again. Aminosilane was added dropwise and the mixture was kept at the temperature to obtain an antibacterial silane-terminated polyurethane resin. S2: Preparation of bio-based ultraviolet absorbers In a three-necked flask equipped with a condenser and a nitrogen inlet, caffeic acid, ethylene carbonate, and TBAB were added. Nitrogen gas was introduced for protection, and the mixture was stirred and heated to maintain the reaction temperature. Heating was then stopped, and after cooling, deionized water was added. The mixture was heated, stirred, and washed. The liquid was filtered off while hot, and the solid product was washed and dried to obtain the DHE-CA monomer. In a reaction flask, the DHE-CA monomer and immobilized lipase Novozym435 were added. The system was sealed, evacuated, heated, and magnetically stirred. Finally, anhydrous ethanol was added, stirred, and the enzyme was recovered by filtration. The resulting liquid product was dried under vacuum after removing the ethanol using a rotary evaporator to obtain a bio-based ultraviolet absorber. S3: Preparation of light-stabilized capsules Bio-based UV absorber and hindered amine light stabilizer GW-622 were dissolved in anhydrous ethanol, and IPTS, HDI and TEOS were added. The mixture was stirred to dissolve and obtain an oil phase. An emulsifier was added to deionized water, followed by the oil phase prepared above. The mixture was emulsified by high-speed shearing to obtain an emulsion. The emulsion was stirred at room temperature, and then n-butanol was added. The mixture was stirred and reacted. The solid product was separated by centrifugation, washed, and vacuum dried to obtain light-stabilized microcapsules. S4: Preparation of weather-resistant and mildew-resistant MS adhesive Antibacterial silane-terminated polyurethane resin, PPG plasticizer, and vinyltrimethoxysilane dehydrating agent were added to a dual planetary mixer and stirred. Nano-calcium carbonate and heavy calcium carbonate were added and dispersed under vacuum conditions. Then, complex coupling agent, thixotropic agent, and light-stabilized microcapsules were added and stirred. Finally, dibutyltin dilaurate catalyst was added and stirred. After discharge, weather-resistant and mildew-resistant MS adhesive was obtained.

2. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 1, characterized in that, Step S1 prepares an antibacterial silane-terminated polyurethane resin, including the following steps: Mix 75-80 parts by weight of polyether diol and 17-25 parts by weight of polyester diol, and dehydrate under vacuum at 110-120°C for 2-2.5 hours. Then cool to 70-80°C, add 42-52 parts by weight of isophorone diisocyanate and 0.05-0.15 parts by weight of organic bismuth catalyst, and react at 70-75°C for 2-3 hours under nitrogen protection to obtain a prepolymer. Add 6-12 parts by weight of trimethoxysilylpropyl dimethyloctadecyl ammonium chloride and 0.1-0.2 parts by weight of dibutyltin dilaurate to the prepolymer, and react at 75-80°C for 1.5 hours. Then cool to 65-70°C, add 25-32 parts by weight of aminosilane dropwise, and keep the reaction at this temperature for 1-1.5 hours to perform silane end-capping to obtain an antibacterial silane-capped polyurethane resin.

3. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 2, characterized in that, Step S2 prepares a bio-based ultraviolet absorber, including the following steps: In a three-necked flask equipped with a condenser and a nitrogen port, add 42-48 parts by weight of caffeic acid, 45-50 parts by weight of ethylene carbonate and 3-4 parts by weight of TBAB, purge with nitrogen for protection, stir and heat to 120-130°C, maintain the temperature for 4-6 hours, then stop heating, cool and add 50-80 parts by weight of deionized water, heat to 60-65°C and stir to wash, filter out the liquid while hot, wash the solid product twice, and dry under vacuum at 60-70°C for 24-26 hours to obtain the DHE-CA monomer; Add 100 parts by mass of DHE-CA monomer and 8-12 parts by mass of immobilized lipase Novozym435 to a reaction flask, seal the system, slowly evacuate to 30-50 mbar using a vacuum pump, and simultaneously raise the temperature to 73-78℃. Stir magnetically at 100-150 r / min for 18-24 hours. Finally, add 30-40 parts by mass of anhydrous ethanol and stir at 40-45℃ for 10-20 minutes. Filter the mixture through a nylon filter cloth to recover the enzyme. Remove the ethanol from the resulting liquid product using a rotary evaporator and then vacuum dry at 50-60℃ to obtain a bio-based ultraviolet absorber.

4. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 3, characterized in that, Step S3 involves preparing photostable capsules, including the following steps: Dissolve 5-7 parts by weight of bio-based UV absorber and 5-7 parts by weight of hindered amine light stabilizer GW-622 in 15-20 parts by weight of anhydrous ethanol, add 1-2 parts by weight of IPTS, 0.5-1 parts by weight of HDI and 5-7 parts by weight of TEOS, and stir to dissolve to obtain the oil phase. Add 0.1-0.2 parts by weight of emulsifier to 40-50 parts by weight of deionized water, then add the oil phase prepared above, and emulsify at high speed of 10000-15000 r / min for 10-20 minutes to obtain an emulsion. Stir the emulsion at room temperature (22-24℃) for 15-30 minutes, then add 1-2 parts by weight of n-butanol, adjust the pH to 8.0-8.5 with ammonia water, stir and react at 40-50℃ for 4-8 hours, centrifuge to separate the solid product, wash with water and ethanol alternately 3 times, and vacuum dry at 40-45℃ for 24-26 hours to obtain photostable microcapsules.

5. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 4, characterized in that, Step S4 involves preparing the weather-resistant and mildew-resistant MS adhesive, including the following steps: In a double planetary mixer, add 100-110 parts by weight of antibacterial silane-terminated polyurethane resin, 30 parts by weight of PPG plasticizer, and 2-3 parts by weight of vinyltrimethoxysilane dehydrating agent. Mix under vacuum ≤−0.09MPa and 200-400 r / min for 15-20 minutes. Add 50-60 parts by weight of nano-calcium carbonate and 20-30 parts by weight of heavy calcium carbonate in two batches, and disperse under vacuum at 800-1200 r / min. The material temperature is controlled below 40℃, and the dispersion time is 30-40 minutes. Then, 3-4 parts by weight of compound coupling agent, 1-2 parts by weight of thixotropic agent and 5-7 parts by weight of light-stabilized microcapsules are added in sequence. Stir at 400-600 r / min under vacuum for 20-30 minutes. Finally, 0.4-0.6 parts by weight of dibutyltin dilaurate catalyst are added, and the mixture is stirred at low speed at 200-300 r / min under vacuum for 10-15 minutes. After discharge, weather-resistant and mildew-resistant MS adhesive is obtained.

6. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 2, characterized in that, The polyether diol is specifically polytetrahydrofuran ether diol, and the polyester diol is specifically polycaprolactone diol.

7. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 4, characterized in that, The emulsifier is specifically sodium dodecyl sulfate.

8. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 5, characterized in that, The compounding agent is specifically prepared by compounding KH-560 and KH-792 in a 1:1 mass ratio.

9. The preparation process of the weather-resistant and mildew-resistant MS adhesive according to claim 5, characterized in that, The thixotropic agent is specifically a polyamide wax.

10. A weather-resistant and mildew-resistant MS adhesive, characterized in that, It is prepared by the preparation process of the weather-resistant and mildew-resistant MS adhesive according to any one of claims 1-9.

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