High-strength mildew-proof ms sealant and preparation method thereof
By grafting antifungal agents into MS sealant and combining them with nanomaterial reinforcement, the problems of short-lasting antifungal performance and insufficient mechanical strength are solved, achieving a balance between high strength and high antifungal performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG LECHAO NEW MATERIAL TECH CO LTD
- Filing Date
- 2026-04-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing MS sealant does not maintain its anti-mildew properties in humid environments, the physically added anti-mildew agents are easily lost, and it is difficult to balance high strength and high flexibility in terms of improving mechanical strength.
The antifungal agent is grafted onto the MS prepolymer. The antifungal agent is grafted onto the side chain of the polyether prepolymer through a maleimide-thiol click chemistry reaction. It is then combined with active nano-calcium carbonate and fumed silica for reinforcement, forming covalent bonds to improve mechanical properties.
It achieves permanent anchoring of the anti-mold agent, ensuring long-lasting and undiminished anti-mold performance, while also improving the mechanical strength and cross-linking ability of the sealant, avoiding the consumption of silane groups by traditional methods.
Smart Images
Figure CN122104119A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of sealant technology, specifically relating to high-strength anti-mildew MS sealant and its preparation method. Background Technology
[0002] Silane-modified polyether sealant, also known as MS sealant, is an environmentally friendly sealing material based on silane-terminated polyether polymers. Its main chain consists of polyether segments, with end groups containing hydrolyzable silane groups. Through moisture-triggered hydrolysis and condensation reactions, it forms a three-dimensional Si-O-Si cross-linked network. Compared to traditional sealing materials, MS sealant combines the flexibility of polyurethane sealant with the weather resistance of silicone sealant. It is solvent-free and has low VOC emissions, making it environmentally friendly. It also exhibits excellent adhesion to various substrates such as metal, glass, and concrete, achieving high-strength bonding without the need for primer treatment. Due to these advantages, MS sealant is widely used in architectural decoration, prefabricated building joint sealing, and automotive manufacturing.
[0003] However, MS sealant still faces several technical bottlenecks that urgently need to be addressed in long-term applications. Firstly, its anti-mold performance is not durable enough. In damp environments such as kitchens, bathrooms, and basements, mold easily grows on the sealant surface. Existing technologies often use physically added anti-mold agents to improve performance, but these agents only have a physical blending effect with the polymer matrix. Over long-term use, they are easily lost due to migration, volatilization, or washing, leading to a decline in anti-mold performance with extended service life. While the invention patent with publication number CN120248815A developed a novel anti-mold agent, it still involves physical mixing and addition to the MS sealant system, retaining the drawback of easy flow failure. Secondly, its mechanical strength needs further improvement. Existing reinforcement methods mainly rely on fillers such as nano-calcium carbonate or increase crosslinking density at the expense of flexibility, making it difficult to achieve a balance between high strength and high elasticity. Furthermore, the physical addition of anti-mold agents does not contribute to mechanical properties and may even affect the integrity of the cured network due to compatibility issues.
[0004] Therefore, developing a high-strength anti-mildew MS sealant that can both permanently anchor the anti-mildew agent and simultaneously improve its mechanical strength is of great technical significance and application value. Summary of the Invention
[0005] The purpose of this invention is to provide a high-strength anti-mildew MS sealant and its preparation method to solve the above-mentioned technical problems.
[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows: High-strength anti-mildew MS sealant, by weight, includes: 100-120 parts of anti-mildew grafted MS prepolymer, 80-100 parts of active nano calcium carbonate, 5-15 parts of fumed silica, 2-4 parts of dehydrating agent, 1-3 parts of coupling agent, and 0.1-0.5 parts of chelated tin catalyst. The antifungal agent-grafted MS prepolymer is a polyether prepolymer with silanoxy-terminated ends and isothiazolinone grafted onto the side chains via a maleimide-thiol click chemistry reaction.
[0007] This invention also provides a method for preparing a high-strength anti-mildew MS sealant, comprising the following steps: dehydrating and stirring an anti-mildew agent-grafted MS prepolymer, active nano-calcium carbonate, and fumed silica at 90-105℃ and -0.095MPa for 2-3 hours; cooling to 20-40℃, adding a dehydrating agent and a coupling agent, and stirring for 10-15 minutes; adding a chelated tin catalyst and vacuum stirring for 15-30 minutes to obtain a high-strength anti-mildew MS sealant.
[0008] As a further improvement, the method for preparing the antifungal agent-grafted MS prepolymer is as follows: S1. Dissolve the maleimide-containing hydroxyl-terminated polyether in anhydrous toluene, add 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate, and react at 60-80°C under a nitrogen atmosphere for 4-8 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain the silane-terminated polyether containing maleimide. S2. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add concentrated hydrochloric acid, and stir at room temperature for 2-4 hours. After the reaction is complete, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere to obtain mercaptoisothiazolinone. S3. Dissolve the silane-terminated polyether containing maleimide in anhydrous toluene, add mercaptoisothiazolinone, then add triethylamine, and stir under a nitrogen atmosphere for 8-16 hours. After the reaction is complete, remove the solvent by vacuum distillation to obtain the antifungal agent-grafted MS prepolymer.
[0009] As a further improvement, in step S1, the mass ratio of the maleimide-containing hydroxyl-terminated polyether, 3-isocyanate-propyltrimethoxysilane, and dibutyltin dilaurate is 100:8~15:0.1~0.5; in step S2, the concentration of the concentrated hydrochloric acid is 36~38%; the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol, and concentrated hydrochloric acid is 1g:5~10mL:0.1~0.3mL; in step S3, the mass ratio of the maleimide-containing silane-terminated polyether, mercaptoisothiazolinone, and triethylamine is 100:2~8:0.1~0.5.
[0010] As a further improvement, the preparation method of the maleimide-containing terminal hydroxyl polyether is as follows: propylene glycol and catalyst BF3·THF are added to anhydrous dichloromethane, and a mixed solution of propylene oxide and maleimide glycidyl ether is slowly added dropwise at 0~5℃ under nitrogen protection; after the addition is completed, the reaction is continued to be stirred at room temperature for 12~24h, washed with saturated sodium bicarbonate solution, the organic phase is collected, concentrated and dried to obtain the maleimide-containing terminal hydroxyl polyether.
[0011] As a further improvement, the molar ratio of propylene oxide to maleimide glycidyl ether is 85~95:5~15; the amount of catalyst BF3·THF added is 0.1~0.5% of the mass of the mixed solution of propylene oxide and maleimide glycidyl ether; and the amount of propylene glycol added is 2~5% of the mass of the mixed solution of propylene oxide and maleimide glycidyl ether.
[0012] As a further improvement, in step S2, the preparation method of 2-(2-acetylthioethyl)-4-isothiazolin-3-one is as follows: N-(acetylthioethyl)-3-mercaptopropamide is dissolved in anhydrous dichloromethane, cooled to 0-5°C in an ice bath under nitrogen protection, and sulfuryl chloride is slowly added dropwise; stirring is continued at room temperature for 2-4 hours; after the reaction is completed, the mixture is evaporated under reduced pressure, the residue is dissolved in ethyl acetate, washed successively with saturated sodium bicarbonate solution and saturated brine, the organic phase is collected, concentrated and dried to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one; wherein the mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to sulfuryl chloride is 1:2-3.3.
[0013] As a further improvement, the preparation method of N-(acetylthioethyl)-3-mercaptopropionamide is as follows: S-(2-aminoethyl)thioacetic acid is dissolved in anhydrous methanol and stirred until dissolved. Methyl 3-mercaptopropionate and sodium methoxide are added, and stirring is continued for 10-30 min. The mixture is heated to 65-70℃ and refluxed for 4-6 h. After the reaction is completed and cooled to room temperature, dilute hydrochloric acid is added to adjust the pH to 7-8. Methanol is removed by rotary evaporation, and dichloromethane is added to dissolve the mixture. Deionized water is then added, and the mixture is shaken to separate into layers. The organic phase is collected, dried, filtered, and the filtrate is collected and concentrated by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide.
[0014] As a further improvement, the molar ratio of S-(2-aminoethyl)thioacetic acid, methyl 3-mercaptopropionate and sodium methoxide is 1~1.2:1:0.05~0.1.
[0015] As a further improvement, the coupling agent is selected from one or more of γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane; the dehydrating agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, or methyltrimethoxysilane.
[0016] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: 1. The high-strength anti-mildew MS sealant provided by this invention permanently anchors the anti-mildew agent to the polyether backbone through chemical bonds. Compared with traditional physical blending or inclusion complex slow-release anti-mildew technology, the anti-mildew agent in this invention is grafted onto the prepolymer side chain in the form of covalent bonds, which fundamentally solves the problem of anti-mildew performance degradation caused by migration, volatilization or water washing during long-term use. At the same time, since the grafting site of the anti-mildew agent is located on the side chain rather than the end group, the consumption of silanoxy groups by traditional end group modification methods is avoided, ensuring the integrity of the prepolymer end silanoxy groups. Thus, while giving the material excellent anti-mildew performance, its curing crosslinking ability and mechanical properties are not sacrificed at all.
[0017] 2. Maleimide glycidyl ether is introduced into the polyether backbone and embedded into the polymer skeleton as a side chain through cationic ring-opening copolymerization. The maleimide double bond retained at one end provides an efficient and specific grafting site for subsequent click chemistry reactions, realizing efficient and controllable grafting of the antifungal agent. In addition, the rigid ring structure contained in the maleimide glycidyl ether monomer itself, after copolymerization, acts as a side group suspended in the main chain, which can effectively increase the rigidity of the polyether chain segment, restrict molecular chain slippage, and thus significantly improve the strength of the sealant. Attached Figure Description
[0018] Figure 1 These are ATR-FTIR images of mercaptoisothiazolinones prepared in Example 1; Figure 2 These are ATR-FTIR images of the silane-terminated polyether with maleimide side chains prepared in Example 1; Figure 3 This is an ATR-FTIR image of the antifungal agent grafted MS prepolymer prepared in Example 1. Detailed Implementation
[0019] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or manufacturer's conditions shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.
[0020] In the embodiments and comparative examples of this invention, the specifications of the raw materials used are uniform as follows: the active nano-calcium carbonate is stearic acid surface modified type, with a particle size of 40~80nm, a specific surface area of 25~35m² / g, and a stearic acid modification ratio of 2.0~3.0wt%; the fumed silica is hydrophobic type, with a particle size of 7~14nm, a specific surface area of 180~220m² / g, modified with dimethyldichlorosilane, and a hydrophobicity ≥90%; the chelated tin catalyst is dibutyltin diacetylacetone chelate.
[0021] Example 1: A method for preparing high-strength anti-mildew MS sealant, comprising the following steps: 1. Dissolve S-(2-aminoethyl)thioacetic acid in anhydrous methanol and stir until dissolved. Add methyl 3-mercaptopropionate and sodium methoxide in a molar ratio of 1:1:0.1. Continue stirring for 20 min and reflux at 65 °C for 5 h. After the reaction is complete and cooled to room temperature, add dilute hydrochloric acid to adjust the pH to 7. Remove methanol by rotary evaporation, dissolve in dichloromethane, add deionized water, shake to separate the layers, collect the organic phase, dry with anhydrous sodium sulfate, filter, collect the filtrate, and concentrate by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide. 2. N-(acetylthioethyl)-3-mercaptopropamide was dissolved in anhydrous dichloromethane and cooled to 4°C in an ice bath under nitrogen protection. Thionyl chloride was slowly added dropwise. The mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to thiopropamide was 1:2.5. The mixture was stirred for 2 hours at room temperature. After the reaction was completed, the mixture was rotary evaporated under reduced pressure. The residue was dissolved in ethyl acetate and washed successively with saturated sodium bicarbonate solution and saturated brine. The organic phase was collected, dried, and concentrated for 12 hours to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one.
[0022] 3. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add 38% concentrated hydrochloric acid, the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol, and concentrated hydrochloric acid is 1 g: 10 mL: 0.2 mL; stir at room temperature for 2 h; after the reaction is complete, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere for 24 h to obtain mercaptoisothiazolinone; the reaction formulas for steps 1 to 3 are shown below: ; The ATR-FTIR image of the mercaptoisothiazolinone-containing sample prepared in this embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen from this that the range is 2540~2560cm -1 The presence of a distinct thiol-characteristic absorption peak at the point indicates the successful preparation of a thiol-containing isothiazolinone. 4. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, at 4°C, a mixed solution of propylene oxide and maleimide glycidyl ether was slowly added dropwise, wherein the molar ratio of propylene oxide to maleimide glycidyl ether was 90:10, and both were soluble in anhydrous dichloromethane. The amounts of propylene glycol and catalyst BF3·THF added were 0.3% and 3% of the total mass of propylene oxide and maleimide glycidyl ether, respectively. After the addition was completed, the reaction was continued to be stirred at room temperature for 12 hours. The mixture was washed with saturated sodium bicarbonate solution, the organic phase was collected, concentrated, and dried. Subsequently, a maleimide-containing terminal hydroxyl polyether was obtained. The maleimide-containing terminal hydroxyl polyether was dissolved in anhydrous toluene, and 3-isocyanopropyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of the maleimide-containing terminal hydroxyl polyether, 3-isocyanopropyltrimethoxysilane, and dibutyltin dilaurate was 100:10:0.5. The reaction was carried out at 70°C under a nitrogen atmosphere for 5 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a maleimide-containing silane-terminated polyether. The reaction expression for step 4 is shown below: ; The ATR-FTIR image of the silane-terminated polyether with maleimide side chain prepared in this embodiment is as follows: Figure 2 As shown, from Figure 2 It can be seen that in the range of 1640~1660cm -1 The characteristic absorption peak of the maleimide double bond appears at 1080~1100 cm⁻¹. -1 The presence of a characteristic absorption peak of silanoxy groups at the point of origin confirms the successful preparation of silane-terminated polyethers with maleimide-containing side chains. 5. Dissolve the silane-terminated polyether containing maleimide in anhydrous toluene, add mercaptoisothiazolinone, and then add triethylamine; the mass ratio of the silane-terminated polyether containing maleimide, mercaptoisothiazolinone, and triethylamine is 100:5:0.5; stir for 10 hours under a nitrogen atmosphere; after the reaction is complete, remove the solvent by vacuum distillation to obtain the antifungal agent-grafted MS prepolymer; the reaction expression in step 5 is shown in the following formula: ; The ATR-FTIR image of the antifungal agent-grafted MS prepolymer prepared in this embodiment is as follows: Figure 3 As shown, from Figure 3 It can be seen from this that 2540~2560cm -1 The characteristic absorption peak of the thiol group has decreased to below the detection limit, 1640~1660 cm⁻¹. -1 The characteristic absorption peak of the maleimide double bond is weakened, while the 1080~1100 cm⁻¹ peak is retained. -1 The presence of characteristic absorption peaks at silanoxy groups indicates that the maleimide-thiol click chemistry reaction occurred, and the isothiazolinone antifungal agent was successfully grafted onto the side chain of the MS prepolymer without damaging the silanoxy structure of the prepolymer end groups. 6. By weight, take 120 parts of antifungal agent-grafted MS prepolymer, 80 parts of active nano-calcium carbonate, 10 parts of fumed silica, 2 parts of vinyltrimethoxysilane, 1 part of γ-aminopropyltrimethoxysilane, and 0.5 parts of chelated tin catalyst; add the antifungal agent-grafted MS prepolymer, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir at 100℃ and a vacuum degree of -0.095MPa for 3 hours; cool to 40℃, add vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane, and stir for 15 minutes; add the chelated tin catalyst, and stir under vacuum for 20 minutes; discharge, seal and package to obtain high-strength antifungal MS sealant.
[0023] Example 2: A method for preparing high-strength anti-mildew MS sealant, comprising the following steps: 1. Dissolve S-(2-aminoethyl)thioacetic acid in anhydrous methanol and stir until dissolved. Add methyl 3-mercaptopropionate and sodium methoxide. The molar ratio of S-(2-aminoethyl)thioacetic acid, methyl 3-mercaptopropionate, and sodium methoxide is 1.2:1:0.05. Continue stirring for 30 min and heat to 70 °C under reflux for 6 h. After the reaction is completed and cooled to room temperature, add dilute hydrochloric acid to adjust the pH to 7.5. Remove methanol by rotary evaporation, dissolve in dichloromethane, add deionized water, shake and separate into layers. Collect the organic phase, dry with anhydrous sodium sulfate, filter, collect the filtrate, and concentrate by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide. 2. N-(acetylthioethyl)-3-mercaptopropamide was dissolved in anhydrous dichloromethane and cooled to 5°C in an ice bath under nitrogen protection. Thionyl chloride was slowly added dropwise. The mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to thiopropamide was 1:3.3. The mixture was stirred at room temperature for 4 hours. After the reaction was completed, the mixture was rotary evaporated under reduced pressure. The residue was dissolved in ethyl acetate and washed successively with saturated sodium bicarbonate solution and saturated brine. The organic phase was collected, dried, and concentrated for 12 hours to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one.
[0024] 3. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add 36% concentrated hydrochloric acid, the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol and concentrated hydrochloric acid is 1g:5mL:0.3mL; stir at room temperature for 4h; after the reaction is completed, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere for 24h to obtain mercaptoisothiazolinone; 4. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, at 5°C, a mixed solution of propylene oxide and maleimide glycidyl ether was slowly added dropwise, wherein the molar ratio of propylene oxide to maleimide glycidyl ether was 85:5, and both were soluble in anhydrous dichloromethane. The amounts of propylene glycol and catalyst BF3·THF added were 0.5% and 5% of the total mass of propylene oxide and maleimide glycidyl ether, respectively. After the addition was complete, the reaction was continued to be stirred at room temperature for 24 hours. The mixture was washed with saturated sodium bicarbonate solution, and the product was collected. After concentration and drying, a hydroxyl-terminated polyether with maleimide side chains was obtained. The hydroxyl-terminated polyether with maleimide side chains was dissolved in anhydrous toluene, and 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of the hydroxyl-terminated polyether with maleimide side chains, 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate was 100:15:0.25. The reaction was carried out at 80°C under a nitrogen atmosphere for 8 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a silane-terminated polyether with maleimide side chains. 5. Dissolve the silane-terminated polyether containing maleimide in anhydrous toluene, add mercaptoisothiazolinone, and add triethylamine; the mass ratio of the silane-terminated polyether containing maleimide, mercaptoisothiazolinone, and triethylamine is 100:8:0.25; stir under a nitrogen atmosphere for 8 hours; after the reaction is complete, remove the solvent by vacuum distillation to obtain the antifungal agent-grafted MS prepolymer; 6. By weight, take 100 parts of antifungal agent-grafted MS prepolymer, 100 parts of active nano-calcium carbonate, 15 parts of fumed silica, 4 parts of vinyltriethoxysilane, 3 parts of γ-aminopropyltriethoxysilane, and 0.25 parts of chelated tin catalyst; add the antifungal agent-grafted MS prepolymer, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir for 2 hours at 105℃ and a vacuum degree of -0.095MPa; cool to 20℃, add vinyltriethoxysilane and γ-aminopropyltriethoxysilane, and stir for 10 minutes; add the chelated tin catalyst, and stir under vacuum for 30 minutes; discharge, seal and package to obtain high-strength antifungal MS sealant.
[0025] Example 3: A method for preparing high-strength anti-mildew MS sealant, comprising the following steps: 1. S-(2-aminoethyl)thioacetic acid was dissolved in anhydrous methanol and stirred until dissolved. Methyl 3-mercaptopropionate and sodium methoxide were added. The molar ratio of S-(2-aminoethyl)thioacetic acid, methyl 3-mercaptopropionate and sodium methoxide was 1.1:1:0.07. The mixture was stirred for 10 min and heated to 68 °C under reflux for 4 h. After the reaction was completed and cooled to room temperature, dilute hydrochloric acid was added to adjust the pH to 8. Methanol was removed by rotary evaporation. Dichloromethane was added to dissolve the mixture. Deionized water was added, and the mixture was shaken to separate the layers. The organic phase was collected, dried with anhydrous sodium sulfate, filtered, and the filtrate was collected and concentrated by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide. 2. N-(acetylthioethyl)-3-mercaptopropamide was dissolved in anhydrous dichloromethane and cooled to 0°C in an ice bath under nitrogen protection. Thionyl chloride was slowly added dropwise. The mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to thiopropamide was 1:2. The mixture was stirred at room temperature for 3 hours. After the reaction was completed, the mixture was rotary evaporated under reduced pressure. The residue was dissolved in ethyl acetate and washed successively with saturated sodium bicarbonate solution and saturated brine. The organic phase was collected, dried, and concentrated for 12 hours to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one.
[0026] 3. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add 37% concentrated hydrochloric acid, the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol and concentrated hydrochloric acid is 1g:7.5mL:0.1mL; stir at room temperature for 3h; after the reaction is completed, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere for 24h to obtain mercaptoisothiazolinone; 4. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, at 0°C, a mixed solution of propylene oxide and maleimide glycidyl ether was slowly added dropwise, wherein the molar ratio of propylene oxide to maleimide glycidyl ether was 95:15, and both were soluble in anhydrous dichloromethane. The amounts of propylene glycol and catalyst BF3·THF added were 0.1% and 2% of the total mass of propylene oxide and maleimide glycidyl ether, respectively. After the addition was complete, the reaction was continued to be stirred at room temperature for 20 hours. The mixture was washed with saturated sodium bicarbonate solution and collected. The organic phase was concentrated and dried to obtain a hydroxyl-terminated polyether with maleimide side chains. The hydroxyl-terminated polyether with maleimide side chains was dissolved in anhydrous toluene, and 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of the hydroxyl-terminated polyether with maleimide side chains, 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate was 100:8:0.1. The reaction was carried out at 60°C under a nitrogen atmosphere for 4 hours. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a silane-terminated polyether with maleimide side chains. 5. Dissolve the silane-terminated polyether containing maleimide in anhydrous toluene, add mercaptoisothiazolinone, and add triethylamine; the mass ratio of the silane-terminated polyether containing maleimide, mercaptoisothiazolinone, and triethylamine is 100:2:0.1; stir for 16 h under a nitrogen atmosphere; after the reaction is completed, remove the solvent by vacuum distillation to obtain the antifungal agent-grafted MS prepolymer; 6. By weight, take 110 parts of antifungal agent-grafted MS prepolymer, 90 parts of active nano-calcium carbonate, 5 parts of fumed silica, 3 parts of methyltrimethoxysilane, 2 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and 0.1 parts of chelated tin catalyst; add the antifungal agent-grafted MS prepolymer, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir at 90℃ and a vacuum degree of -0.095MPa for 2.5h; cool to 30℃, add methyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane, and stir for 12min; add the chelated tin catalyst, and stir under vacuum for 15min; discharge, seal and package to obtain high-strength antifungal MS sealant.
[0027] Comparative Example 1: The preparation method of high-strength anti-mildew MS sealant differs from Example 1 in that it does not graft mercaptoisothiazolinone onto the polyether chain, and includes the following steps: 1. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, at 4°C, a mixed solution of propylene oxide and maleimide glycidyl ether was slowly added dropwise, wherein the molar ratio of propylene oxide to maleimide glycidyl ether was 90:10, and both were soluble in anhydrous dichloromethane. The amounts of propylene glycol and catalyst BF3·THF added were 0.3% and 3% of the total mass of propylene oxide and maleimide glycidyl ether, respectively. After the addition was complete, the reaction was continued to be stirred at room temperature for 12 hours. The mixture was washed with saturated sodium bicarbonate solution and collected. The organic phase was concentrated and dried to obtain a hydroxyl-terminated polyether with maleimide side chains. The hydroxyl-terminated polyether with maleimide side chains was dissolved in anhydrous toluene, and 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of the hydroxyl-terminated polyether with maleimide side chains, 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate was 100:10:0.5. The reaction was carried out at 70°C under a nitrogen atmosphere for 5 h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a silane-terminated polyether with maleimide side chains. 2. By weight, take 120 parts of silane-terminated polyether with maleimide side chains, 80 parts of active nano-calcium carbonate, 10 parts of fumed silica, 2 parts of vinyltrimethoxysilane, 1 part of γ-aminopropyltrimethoxysilane, and 0.5 parts of chelated tin catalyst; add the silane-terminated polyether with maleimide side chains, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir for 3 hours at 100℃ and a vacuum degree of -0.095MPa; cool to 40℃, add vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane, and stir for 15 minutes; add the chelated tin catalyst, and stir under vacuum for 20 minutes; discharge, seal and package to obtain MS sealant.
[0028] Comparative Example 2: The preparation method of high-strength anti-mildew MS sealant differs from that of Example 1 in that the silane-terminated polyether containing mercaptoisothiazolinone and maleimide was not pre-reacted, but only physically mixed, including the following steps: 1. Dissolve S-(2-aminoethyl)thioacetic acid in anhydrous methanol and stir until dissolved. Add methyl 3-mercaptopropionate and sodium methoxide in a molar ratio of 1:1:0.1. Continue stirring for 20 min and reflux at 65 °C for 5 h. After the reaction is complete and cooled to room temperature, add dilute hydrochloric acid to adjust the pH to 7. Remove methanol by rotary evaporation, dissolve in dichloromethane, add deionized water, shake to separate the layers, collect the organic phase, dry with anhydrous sodium sulfate, filter, collect the filtrate, and concentrate by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide. 2. N-(acetylthioethyl)-3-mercaptopropamide was dissolved in anhydrous dichloromethane and cooled to 4°C in an ice bath under nitrogen protection. Thionyl chloride was slowly added dropwise. The mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to thiopropamide was 1:2.5. The mixture was stirred for 2 hours at room temperature. After the reaction was completed, the mixture was rotary evaporated under reduced pressure. The residue was dissolved in ethyl acetate and washed successively with saturated sodium bicarbonate solution and saturated brine. The organic phase was collected, dried, and concentrated for 12 hours to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one.
[0029] 3. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add 38% concentrated hydrochloric acid, the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol and concentrated hydrochloric acid is 1g:10mL:0.2mL; stir at room temperature for 2h; after the reaction is completed, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere for 24h to obtain mercaptoisothiazolinone; 4. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, at 4°C, a mixed solution of propylene oxide and maleimide glycidyl ether was slowly added dropwise, wherein the molar ratio of propylene oxide to maleimide glycidyl ether was 90:10, and both were soluble in anhydrous dichloromethane. The amounts of propylene glycol and catalyst BF3·THF added were 0.3% and 3% of the total mass of propylene oxide and maleimide glycidyl ether, respectively. After the addition was complete, the reaction was continued to be stirred at room temperature for 12 hours. The mixture was washed with saturated sodium bicarbonate solution and collected. The organic phase was concentrated and dried to obtain a hydroxyl-terminated polyether with maleimide side chains. The hydroxyl-terminated polyether with maleimide side chains was dissolved in anhydrous toluene, and 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of the hydroxyl-terminated polyether with maleimide side chains, 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate was 100:10:0.5. The reaction was carried out at 70°C under a nitrogen atmosphere for 5 h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a silane-terminated polyether with maleimide side chains. 5. By weight, take 6 parts of mercaptoisothiazolinone, 114 parts of silane-terminated polyether with maleimide side chain, 80 parts of active nano-calcium carbonate, 10 parts of fumed silica, 2 parts of vinyltrimethoxysilane, 1 part of γ-aminopropyltrimethoxysilane, and 0.5 parts of chelated tin catalyst; add mercaptoisothiazolinone, silane-terminated polyether, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir for 3 hours at 100℃ and a vacuum degree of -0.095MPa; cool to 40℃, add vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane, and stir for 15 minutes; add chelated tin catalyst, and stir under vacuum for 20 minutes; discharge, seal and package to obtain MS sealant.
[0030] Comparative Example 3: The preparation method of high-strength anti-mildew MS sealant differs from Example 1 in that maleimide glycidyl ether was not used, and includes the following steps: 1. Dissolve S-(2-aminoethyl)thioacetic acid in anhydrous methanol and stir until dissolved. Add methyl 3-mercaptopropionate and sodium methoxide in a molar ratio of 1:1:0.1. Continue stirring for 20 min and reflux at 65 °C for 5 h. After the reaction is complete and cooled to room temperature, add dilute hydrochloric acid to adjust the pH to 7. Remove methanol by rotary evaporation, dissolve in dichloromethane, add deionized water, shake to separate the layers, collect the organic phase, dry with anhydrous sodium sulfate, filter, collect the filtrate, and concentrate by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide. 2. N-(acetylthioethyl)-3-mercaptopropamide was dissolved in anhydrous dichloromethane and cooled to 4°C in an ice bath under nitrogen protection. Thionyl chloride was slowly added dropwise. The mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to thiopropamide was 1:2.5. The mixture was stirred for 2 hours at room temperature. After the reaction was completed, the mixture was rotary evaporated under reduced pressure. The residue was dissolved in ethyl acetate and washed successively with saturated sodium bicarbonate solution and saturated brine. The organic phase was collected, dried, and concentrated for 12 hours to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one.
[0031] 3. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add 38% concentrated hydrochloric acid, the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol and concentrated hydrochloric acid is 1g:10mL:0.2mL; stir at room temperature for 2h; after the reaction is completed, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere for 24h to obtain mercaptoisothiazolinone; 4. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, propylene oxide dissolved in anhydrous dichloromethane was slowly added dropwise at 4°C. The amounts of propylene glycol and catalyst BF3·THF added were 0.3% and 3% of the mass of propylene oxide, respectively. After the addition was completed, the reaction was continued to be stirred at room temperature for 12 h. The mixture was washed with saturated sodium bicarbonate solution, the organic phase was collected, concentrated and dried to obtain hydroxyl-terminated polyether. The hydroxyl-terminated polyether was dissolved in anhydrous toluene, and 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of hydroxyl-terminated polyether, 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate was 100:10:0.5. The reaction was carried out at 70°C under a nitrogen atmosphere for 5 h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain silane-terminated polyether. 5. By weight, take 6 parts of mercaptoisothiazolinone, 114 parts of silane-terminated polyether, 80 parts of active nano-calcium carbonate, 10 parts of fumed silica, 2 parts of vinyltrimethoxysilane, 1 part of γ-aminopropyltrimethoxysilane, and 0.5 parts of chelated tin catalyst; add mercaptoisothiazolinone, silane-terminated polyether, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir at 100℃ and a vacuum of -0.095MPa for 3 hours; cool to 40℃, add vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane, and stir for 15 minutes; add chelated tin catalyst, and stir under vacuum for 20 minutes; discharge, seal and package to obtain MS sealant.
[0032] Comparative Example 4: The preparation method of high-strength anti-mildew MS sealant differs from Example 1 in that it uses commercially available anti-mildew agent OIT mixed with polyether, including the following steps: 1. Propylene glycol and catalyst BF3·THF were added to anhydrous dichloromethane. Under nitrogen protection, at 4°C, a mixed solution of propylene oxide and maleimide glycidyl ether was slowly added dropwise, wherein the molar ratio of propylene oxide to maleimide glycidyl ether was 90:10, and both were soluble in anhydrous dichloromethane. The amounts of propylene glycol and catalyst BF3·THF added were 0.3% and 3% of the total mass of propylene oxide and maleimide glycidyl ether, respectively. After the addition was complete, the reaction was continued to be stirred at room temperature for 12 hours. The mixture was washed with saturated sodium bicarbonate solution and collected. The organic phase was concentrated and dried to obtain a hydroxyl-terminated polyether with maleimide side chains. The hydroxyl-terminated polyether with maleimide side chains was dissolved in anhydrous toluene, and 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate were added. The mass ratio of the hydroxyl-terminated polyether with maleimide side chains, 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate was 100:10:0.5. The reaction was carried out at 70°C under a nitrogen atmosphere for 5 h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain a silane-terminated polyether with maleimide side chains. 2. By weight, take 114 parts of silane-terminated polyether containing maleimide side chains, 6 parts of commercially available antifungal agent OIT, 80 parts of active nano-calcium carbonate, 10 parts of fumed silica, 2 parts of vinyltrimethoxysilane, 1 part of γ-aminopropyltrimethoxysilane, and 0.5 parts of chelated tin catalyst; add the silane-terminated polyether containing maleimide side chains, commercially available antifungal agent, active nano-calcium carbonate, and fumed silica to a planetary mixer, and dehydrate and stir for 3 hours at 100℃ and a vacuum degree of -0.095MPa; cool to 40℃, add vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane, and stir for 15 minutes; add the chelated tin catalyst, and stir under vacuum for 20 minutes; discharge, seal and package to obtain MS sealant.
[0033] Performance testing 1. Anti-mildew performance test The test was conducted in accordance with the national standard GB / T 1741-2020, "Determination of resistance to mold and mildew in paint films".
[0034] In the examples, the MS sealant prepared in Examples 1-3 and Comparative Examples 1-4 was made into standard test plates. After being sterilized by ultraviolet light, a mixed spore suspension (Aspergillus niger, Aspergillus flavus, Chaetomium globosum, etc.) was sprayed on the plates and cultured in an incubator at 28°C and 95% relative humidity for 28 days. The growth of mold was then observed.
[0035] The following rating standards are used to determine the initial anti-mold rating: Grade 0: No obvious growth; Grade 1: Trace growth (less than 10%); Grade 2: Slight growth (10%-30%); Grade 3: Moderate growth (30%-60%); Grade 4: Heavy growth (more than 60%). Simultaneously, an anti-mold durability test is conducted: the test panel is immersed in deionized water at 25℃ for 7 days, then removed and dried. The anti-mold rating is then tested again using the method described above to determine the durable anti-mold rating.
[0036] The experimental results are shown in Table 1: Table 1. Results of Anti-mildew Performance Tests
[0037] As can be seen from Table 1, the initial and durable anti-mold grades of Examples 1-3 all reached grade 0, demonstrating excellent and long-lasting anti-mold performance. This is attributed to the grafting of the isothiazolinone anti-mold group onto the side chain of the MS prepolymer via maleimide-thiol click chemistry, which effectively prevents the migration and loss of the anti-mold agent and maintains high anti-mold activity even after soaking in water for 7 days.
[0038] Comparative Example 1, without any antifungal agent, had an initial antifungal rating of only 3, which further deteriorated to 4 after soaking in water, indicating that sealant lacking antifungal components is highly susceptible to mold erosion. Comparative Example 2 added mercaptoisothiazolinone, but it was only a physical mixture. Comparative Example 3, due to the lack of maleimide reaction sites on the polyether chain, could not be grafted, and both had an initial antifungal rating of 1, indicating some antifungal properties, but both dropped to 3 after soaking in water, indicating that physically mixed or non-chemically bonded antifungal agents were largely lost during soaking, resulting in a significant reduction in antifungal durability. Comparative Example 4 used the commercially available small-molecule antifungal agent OIT, with an initial antifungal rating of 2, which also dropped to 3 after soaking in water, proving that small-molecule antifungal agents are more prone to migration and precipitation, making it difficult to maintain a long-lasting antifungal effect.
[0039] 2. Long-term stability observation The MS sealant prepared in Examples 1-3 and Comparative Examples 1-4 was prepared into sample blocks and placed at a temperature of 23±2℃ and a humidity of 50±5% for 6 months. The appearance changes of the sample blocks were observed, including surface condition, color change, presence of cracks, and presence of mold spots.
[0040] The experimental results are shown in Table 2: Table 2 Long-term stability test results
[0041] As shown in Table 2, after being placed at a temperature of 23±2℃ and a humidity of 50±5% for 6 months, the surfaces of Examples 1-3 remained smooth, free of mold spots and cracks, and exhibited good elasticity, demonstrating excellent long-term stability. This is attributed to the fact that the antifungal agent is firmly grafted onto the side chains of the MS prepolymer through chemical bonds, which not only prevents the migration and loss of the antifungal agent but also avoids the damage to the matrix structure caused by the precipitation of small molecules. In addition, the introduced maleimide glycidyl ether can form a stronger interfacial bond with the active nano-calcium carbonate filler, enhancing the integrity of the polymer network and maintaining good elasticity and structural stability.
[0042] Comparative Example 1, while showing no cracks and good elasticity, exhibited noticeable mold spots on its surface, indicating that the sealant without added antifungal agent was susceptible to mold contamination during long-term storage. Comparative Example 2 showed slight mold spots on its surface but no cracks and good elasticity, suggesting that while the physically mixed antifungal agent had some initial effect, some of it might slowly migrate to the surface or be consumed after long-term storage, leading to a decrease in localized antifungal ability. Comparative Example 3 not only showed slight mold spots on its surface but also exhibited slight edge cracks and decreased elasticity. Due to the absence of maleimide glycidyl ether, it lacked reaction sites, making it impossible to graft antifungal agent onto it. Furthermore, it affected the regularity of the chain segments and the interfacial interaction with the filler, resulting in an insufficiently dense cross-linked network and signs of aging after long-term storage. This indirectly demonstrates that the introduction of maleimide glycidyl ether not only achieves chemical fixation of the antifungal agent but also enhances the strength and durability of the polymer matrix. Comparative Example 4 showed a small number of mold spots on its surface but no cracks and good elasticity, indicating that the commercially available small-molecule antifungal agent OIT gradually migrated and precipitated during long-term storage, leading to a decrease in its antifungal effect.
[0043] 3. Mechanical property testing The test was conducted in accordance with the national standard GB / T 13477.8-2017 "Test methods for building sealing materials - Part 8: Determination of tensile adhesion".
[0044] The MS sealants prepared in Examples 1-3 and Comparative Examples 1-4 were made into standard specimens. After being placed at a temperature of (23±2)℃ and a relative humidity of (50±5)% for 28 days, the tensile strength was tested. The test results are shown in Table 3. Table 3 Mechanical Performance Test Results
[0045] As can be seen from Table 3, the tensile strength of Examples 1-3 is significantly higher than that of Comparative Examples 1-4, exhibiting excellent mechanical properties. This is because grafting isothiazolinone onto the side chain of the MS prepolymer results in a grafted antifungal molecule containing polar groups, which can form hydrogen bonds with the hydroxyl groups on the surface of the active nano-calcium carbonate filler, significantly enhancing the interfacial bonding force between the filler and the polymer matrix, thereby effectively improving the tensile strength. Secondly, the introduction of maleimide glycidyl ether into the copolymerization also increases the polarity and segment rigidity of the polyether backbone, which helps to improve the compatibility and interaction between the polymer and the filler, further promoting the reinforcing effect.
[0046] Comparative Example 1 did not add any antifungal agent and lacked interfacial reinforcement, thus its tensile strength decreased compared to the examples. Comparative Example 2 added a mercaptoisothiazolinone, but it was only a physical mixture, so the antifungal agent was easily lost and lacked strong chemical bonding with the polymer matrix, thus its tensile strength also decreased. Comparative Example 3 did not use maleimide glycidyl ether, and the polyether chain lacked reactive sites, which not only prevented the grafting of antifungal agents but also affected the polarity of the polymer chain and its interaction with the filler, resulting in the lowest tensile strength. Comparative Example 4 used the commercially available small molecule antifungal agent OIT. The small molecule antifungal agent played a plasticizing role in the system, weakening the inter-polymer chain forces and affecting the strength of the MS sealant.
[0047] The above results indicate that the introduction of maleimide glycidyl ether and its grafting of antifungal agents via click chemistry are key technologies for achieving high strength sealants.
[0048] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A high-strength, mildew-resistant MS sealant, characterized in that, By weight, it includes the following components: 100-120 parts of antifungal agent grafted MS prepolymer, 80-100 parts of active nano calcium carbonate, 5-15 parts of fumed silica, 2-4 parts of dehydrating agent, 1-3 parts of coupling agent and 0.1-0.5 parts of chelated tin catalyst; The antifungal agent-grafted MS prepolymer is a polyether prepolymer with silanoxy-terminated ends and isothiazolinone grafted onto the side chains via a maleimide-thiol click chemistry reaction.
2. The high-strength anti-mildew MS sealant according to claim 1, characterized in that, The coupling agent is selected from one or more of γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-aminopropyltriethoxysilane; the dehydrating agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, or methyltrimethoxysilane.
3. A method for preparing the high-strength anti-mildew MS sealant according to claim 1, characterized in that, Includes the following steps: The antifungal agent-grafted MS prepolymer, active nano-calcium carbonate, and fumed silica were dehydrated and stirred at 90~105℃ and -0.095MPa for 2~3h; cooled to 20~40℃, a dehydrating agent and a coupling agent were added, and stirred for 10~15min; a chelated tin catalyst was added, and the mixture was stirred under vacuum for 15~30min to obtain a high-strength antifungal MS sealant.
4. The preparation method of the high-strength anti-mildew MS sealant according to claim 3, characterized in that, The preparation method of the antifungal agent-grafted MS prepolymer is as follows: S1. Dissolve the maleimide-containing hydroxyl-terminated polyether in anhydrous toluene, add 3-isocyanate-propyltrimethoxysilane and dibutyltin dilaurate, and react at 60-80°C under a nitrogen atmosphere for 4-8 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain the silane-terminated polyether containing maleimide. S2. Dissolve 2-(2-acetylthioethyl)-4-isothiazolin-3-one in anhydrous methanol, add concentrated hydrochloric acid, and stir at room temperature for 2-4 hours. After the reaction is complete, remove methanol by rotary evaporation under reduced pressure, dissolve in ethyl acetate, wash with saturated sodium bicarbonate solution, collect the organic phase, concentrate and dry under nitrogen atmosphere to obtain mercaptoisothiazolinone. S3. Dissolve the silane-terminated polyether containing maleimide in anhydrous toluene, add mercaptoisothiazolinone, then add triethylamine, and stir under a nitrogen atmosphere for 8-16 hours. After the reaction is complete, remove the solvent by vacuum distillation to obtain the antifungal agent-grafted MS prepolymer.
5. The preparation method of the high-strength anti-mildew MS sealant according to claim 4, characterized in that, In step S1, the mass ratio of the maleimide-containing hydroxyl-terminated polyether, 3-isocyanate-propyltrimethoxysilane, and dibutyltin dilaurate is 100:8~15:0.1~0.5; in step S2, the concentration of the concentrated hydrochloric acid is 36~38%; the ratio of 2-(2-acetylthioethyl)-4-isothiazolin-3-one, anhydrous methanol, and concentrated hydrochloric acid is 1g:5~10mL:0.1~0.3mL; in step S3, the mass ratio of the maleimide-containing silane-terminated polyether, mercaptoisothiazolinone, and triethylamine is 100:2~8:0.1~0.
5.
6. The preparation method of the high-strength anti-mildew MS sealant according to claim 4, characterized in that, In step S1, the preparation method of the maleimide-containing terminal hydroxyl polyether is as follows: propylene glycol and catalyst BF3·THF are added to anhydrous dichloromethane, and a mixed solution of propylene oxide and maleimide glycidyl ether is slowly added dropwise at 0~5℃ under nitrogen protection; after the addition is completed, the reaction is continued to be stirred at room temperature for 12~24h, washed with saturated sodium bicarbonate solution, the organic phase is collected, concentrated and dried to obtain the maleimide-containing terminal hydroxyl polyether.
7. The preparation method of the high-strength anti-mildew MS sealant according to claim 6, characterized in that, The molar ratio of propylene oxide to maleimide glycidyl ether is 85-95:5-15; the amount of catalyst BF3·THF added is 0.1-0.5% of the mass of the mixed solution of propylene oxide and maleimide glycidyl ether; the amount of propylene glycol added is 2-5% of the mass of the mixed solution of propylene oxide and maleimide glycidyl ether.
8. The preparation method of the high-strength anti-mildew MS sealant according to claim 4, characterized in that, In step S2, the preparation method of 2-(2-acetylthioethyl)-4-isothiazolin-3-one is as follows: N-(acetylthioethyl)-3-mercaptopropamide is dissolved in anhydrous dichloromethane, cooled to 0-5°C in an ice bath under nitrogen protection, and sulfuryl chloride is slowly added dropwise; stirring is continued at room temperature for 2-4 hours. After the reaction is completed, the mixture is evaporated under reduced pressure. The residue is dissolved in ethyl acetate and washed successively with saturated sodium bicarbonate solution and saturated brine. The organic phase is collected, concentrated, and dried to obtain 2-(2-acetylthioethyl)-4-isothiazolin-3-one; wherein the mass ratio of N-(acetylthioethyl)-3-mercaptopropamide to sulfuryl chloride is 1:2-3.
3.
9. The preparation method of the high-strength anti-mildew MS sealant according to claim 8, characterized in that, The preparation method of N-(acetylthioethyl)-3-mercaptopropionamide is as follows: S-(2-aminoethyl)thioacetic acid is dissolved in anhydrous methanol and stirred until dissolved. Methyl 3-mercaptopropionate and sodium methoxide are added, and stirring is continued for 10-30 min. The mixture is heated to 65-70℃ and refluxed for 4-6 h. After the reaction is completed and cooled to room temperature, dilute hydrochloric acid is added to adjust the pH to 7-8. Methanol is removed by rotary evaporation, and dichloromethane is added to dissolve the mixture. Deionized water is then added, and the mixture is shaken to separate into layers. The organic phase is collected, dried, filtered, and the filtrate is collected and concentrated by rotary evaporation to obtain N-(acetylthioethyl)-3-mercaptopropionamide.
10. The preparation method of the high-strength anti-mildew MS sealant according to claim 9, characterized in that, The molar ratio of S-(2-aminoethyl)thioacetic acid, methyl 3-mercaptopropionate, and sodium methoxide is 1~1.2:1:0.05~0.1.