A water repellent and preparation method thereof

Abstract

The present invention relates to the technical field of building waterproofing, and specifically discloses a water repellent and a preparation method thereof. The water repellent comprises: polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier, and deionized water; the preparation method of the water repellent comprises: heating deionized water, adding composite emulsifier, and stirring evenly to obtain emulsion; adding polysiloxane, isobutyl triethoxysilane, acrylic copolymer, and sodium methyl silicate to the emulsion while stirring, and adjusting the pH value of the system to 4.5-6.0 to obtain; the present invention has simple formula selection, simple preparation method, and is suitable for industrial production. The obtained water repellent has good fluidity and construction adaptability, and is coated on the surface of cement foam insulation board or block, and has good bonding, waterproofness, deep penetration, weather resistance, wear resistance and crack resistance, and the waterproof effect is long-lasting.

Description

Technical Field

[0001] The invention relates to the technical field of building waterproofing, and more particularly to a water repellent and a preparation method thereof. Background Art

[0002] Water repellent refers to a class of chemical substances that can make the surface of materials show water repellent properties. Its main function is to reduce the penetration and adsorption of water by changing the physical and chemical properties of the material surface, thereby improving the waterproof performance of the material. Water repellents are widely used in many fields such as construction, coatings, textiles, paper, etc. Among them, silicone water repellent is the most common type. Due to its unique chemical structure, it performs well in terms of water repellency, aging resistance, chemical stability, etc. It is especially suitable for application scenarios such as building exterior wall waterproofing, bathroom and kitchen waterproofing. The core of silicone water repellent is a polysiloxane structure with low critical surface tension. It can effectively penetrate into the micropores of porous materials and effectively prevent water from entering the material by forming a hydrophobic film, thereby improving the durability and safety of the building.

[0003] With the continuous improvement of the construction industry's requirements for energy conservation and environmental protection, cement foam insulation boards or blocks are widely used in building exterior wall insulation systems due to their advantages of light weight, low thermal conductivity, good thermal insulation, high temperature resistance, aging resistance, and A1 non-combustibility. However, due to their porous structure, cement foam insulation boards or blocks are prone to rapid absorption of moisture in a humid environment, and their high water absorption makes them significantly insufficient in waterproof performance. Studies have shown that moisture content affects the thermal insulation performance and strength of the material, which in turn affects the durability and safety of the overall building. Applying organosilicon water repellent to the surface treatment of cement foam insulation boards or blocks can effectively improve their waterproof performance. By coating or adding organosilicon water repellent on the surface of cement foam insulation boards or blocks, an effective water repellent film can be formed on their surface, significantly reducing water absorption and improving the thermal insulation performance and compressive strength of the material.

[0004] Although organosilicon water repellents can improve the waterproof performance of cement foam insulation boards or blocks to a certain extent, there are still some problems in practical applications. The penetration depth of existing organosilicon water repellents on the surface of cement foam insulation boards or blocks is usually shallow, and the protection of the waterproof coating is limited to the surface layer, which fails to effectively improve the waterproof performance of the internal structure of the insulation board; in addition, the existing organosilicon waterproof coating is prone to aging, shedding, and failure when exposed to sunlight and climate change for a long time, which reduces the long-term waterproof ability of the insulation board, etc. Based on the above statements, the present invention proposes a water repellent and a preparation method thereof. Summary of the invention

[0005] In order to solve the problems that the penetration depth of existing organosilicon water repellents on the surface of cement foam insulation boards or blocks is usually shallow, the protection of the waterproof coating is limited to the surface layer, and the waterproof performance of the internal structure of the insulation board is not effectively improved; the organosilicon waterproof coating is prone to aging, shedding, failure and other problems when exposed to sunlight and climate change for a long time, the present invention provides a water repellent and a preparation method thereof.

[0006] In the first aspect, the present invention provides a water repellent, which adopts the following technical solution:

[0007] A water repellent comprises the following raw materials in parts by weight: 40-60 parts of polysiloxane, 15-25 parts of isobutyl triethoxy silane, 5-10 parts of sodium methyl silicate, 8-12 parts of acrylic copolymer, 4-8 parts of composite emulsifier and 30-50 parts of deionized water.

[0008] Preferably, the water repellent comprises the following raw materials in parts by weight: 45-55 parts of polysiloxane, 18-22 parts of isobutyltriethoxysilane, 6-9 parts of sodium methyl silicate, 9-11 parts of acrylic copolymer, 5-7 parts of composite emulsifier, and 35-45 parts of deionized water.

[0009] Preferably, the water repellent comprises the following raw materials in parts by weight: 50 parts of polysiloxane, 20 parts of isobutyltriethoxysilane, 8 parts of sodium methyl silicate, 10 parts of acrylic copolymer, 6 parts of composite emulsifier, and 40 parts of deionized water.

[0010] Preferably, the polysiloxane is polydimethylsiloxane.

[0011] Preferably, the acrylic acid copolymer is prepared by the following method:

[0012] (1) adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to a solvent, mixing them evenly under stirring, and reacting them at 30-40° C. for 2-3 hours to obtain a modified monomer;

[0013] (2) The modified monomer, dimethacrylate urethane and initiator are mixed uniformly under stirring, and heated to 70-80°C under protective gas to carry out polymerization reaction for 3-5 hours. After the reaction is completed, the temperature is lowered, the mixture is concentrated under reduced pressure, and vacuum dried to obtain an acrylic copolymer.

[0014] Preferably, in step (1), the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and solvent is 2-5:2-5:40-50:20-30:100.

[0015] Preferably, the solvent in step (1) is acetone or ethanol.

[0016] Preferably, in step (2), the ratio of the modified monomer, dimethacrylate urethane and initiator is 70-80:5-10:0.05-0.1.

[0017] Preferably, the initiator in step (2) is potassium persulfate.

[0018] Preferably, the composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 3-5:1.

[0019] Preferably, the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0020] A. After mixing vegetable oil with deionized water, add an acid catalyst, heat to 70-80°C, stir and react for 1-3 hours, ensure that the oil and water phases are separated, and stand to separate the layers to obtain free fatty acids;

[0021] B. Add free fatty acid and nickel catalyst into a reactor, exclude air, fill with hydrogen until the pressure in the reactor is 5-6 MPa, then heat to 140-160° C., react for 2-4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0022] C. Mix the hydrogenated fatty acid and epichlorohydrin, stir and react at 50-70°C for 2-4 hours. After the reaction is completed, add deionized water and stir evenly, let it stand and separate into layers. After removing the aqueous phase, evaporate and remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0023] Preferably, the vegetable oil in step A is soybean oil or palm oil.

[0024] Preferably, the acid catalyst in step A is sulfuric acid.

[0025] Preferably, in step A, the mass ratio of vegetable oil, deionized water and acid catalyst is 100:200:0.8-1.2.

[0026] Preferably, in step B, the mass ratio of free fatty acid to nickel catalyst is 70-90:3-5.

[0027] Preferably, the nickel catalyst in step B is nickelous oxide.

[0028] Preferably, in step C, the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water is 2-4:1:5-7.

[0029] In a second aspect, the present invention provides a method for preparing a water repellent, using the following technical solution:

[0030] A method for preparing a water repellent comprises the following steps:

[0031] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0032] S2. Heat deionized water to 50-60°C, add the composite emulsifier and stir evenly to obtain an emulsion;

[0033] S3. Add polysiloxane and isobutyl triethoxysilane to the emulsion while stirring, continue stirring for 5-10 minutes, add acrylic copolymer and continue stirring for 20-30 minutes, finally add sodium methyl silicate and stir for 10-20 minutes, adjust the pH value of the system to 4.5-6.0, and obtain the desired water repellent.

[0034] In summary, the present invention has the following beneficial effects:

[0035] 1. The present invention uses polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water to prepare the required water repellent, wherein polysiloxane is the main substrate component responsible for providing water repellency, flexibility and weather resistance; the introduction of isobutyl triethoxysilane and sodium methyl silicate can form a cross-linked network during the curing process, further improving the structural integrity of the waterproof film, and enhancing the water repellency and durability; sodium methyl silicate can also enhance the interaction force with the substrate surface, thereby improving the adhesion of the waterproof coating and enhancing the stability of the waterproof coating; the addition of acrylic copolymer can, on the one hand, be well compatible with other components such as silane to form a stable network structure, improve the flexibility and adhesion of the waterproof coating, and make it stick to the substrate surface. On the one hand, a durable and stable waterproof film is formed, thereby improving the overall waterproof performance, aging resistance and wear resistance of the waterproof coating; on the other hand, it can work together with the small molecular structure of the organic silicon component to promote the water-repellent agent to penetrate into the micropores of the substrate, thereby ensuring the formation of a deep and effective waterproof layer; the addition of the composite emulsifier can effectively reduce the interfacial tension of each component in the water-repellent agent system, thereby ensuring the formation of a stable emulsion, improving the coating uniformity and waterproof performance, and at the same time helping the water-repellent agent to better penetrate into the interior of the substrate; the invention has a simple formula, a simple preparation method, and is suitable for industrial production; the obtained water-repellent agent has good fluidity and construction adaptability; when coated on the surface of the cement foam insulation board or the block, it has good bonding, waterproofness, deep penetration, weather resistance, wear resistance and crack resistance, and a durable waterproof effect.

[0036] 2. The acrylic copolymer of the present invention is prepared by modifying methyl methacrylate and 2-hydroxyethyl acrylate with heptadecafluorodecyltrimethoxysilane and trifluoropropyltrichlorosilane, and then introducing dimethacrylate carbamate for polymerization reaction. The modification with heptadecafluorodecyltrimethoxysilane and trifluoropropyltrichlorosilane can form a fluorinated layer on the surface of the waterproof coating, which significantly improves the hydrophobicity while providing excellent chemical stability and weather resistance, and reduces the degradation and failure of the coating. The introduction of dimethacrylate carbamate can further enhance the chemical resistance, toughness and impact resistance of the copolymer, and improve the crack resistance and durability of the waterproof coating. The acrylic copolymer added in the present invention has good compatibility with other components in the water repellent system, can improve the fluidity of the system, improve the weather resistance, flexibility, substrate adhesion and substrate penetration depth of the water repellent, and thus improve the waterproof effect and durability of the final waterproof layer.

[0037] 3. The present invention adopts isomeric tridecanol polyoxyethylene ether and auxiliary addition of epoxidized hydrogenated fatty acid ester to jointly form a composite emulsifier; wherein, isomeric tridecanol polyoxyethylene ether as a nonionic surfactant can be effectively adsorbed on the oil-water interface, reduce interfacial tension, promote the dispersion of the two phases, ensure the formation of a stable emulsion, and improve the coating uniformity and waterproof performance; epoxidized hydrogenated fatty acid ester also has good interfacial activity, can form a stable interface between water and oil phases, and enhance the stability of the system through chemical and physical adsorption mechanisms; the composite emulsifier can form a multi-layer interface in the hydrophobic agent system, reduce the aggregation and stratification of the emulsion, thereby forming a stable emulsion; its good emulsifying properties enable the hydrophobic agent to better penetrate into the microstructure of the substrate to form a deeper waterproof effect; through the delicate emulsion structure, the hydrophobic agent can form a stable coating inside the substrate to prevent water penetration. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a diagram showing the effect of the hydrophobic test sample in Example 1 of the present invention not absorbing water after being dripped with water for 24 hours. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below with reference to the embodiments.

[0040] Unless otherwise specified, the materials, reagents, etc. used in the present invention can be obtained from commercial sources.

[0041] Among them, polydimethylsiloxane, CAS No. 9006-65-9, viscosity 500, was purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0042] Heptadecafluorodecyltrimethoxysilane (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltrimethoxysilane), CAS No. 83048-65-1, was purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd.;

[0043] Trifluoropropyltrichlorosilane (trichloro(3,3,3-trifluoropropyl)silane), CAS No. 592-09-6, purchased from Hubei Watson Chemical Technology Co., Ltd.;

[0044] Dimethacrylate carbamate, CAS No. 72869-86-4, was purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd.;

[0045] Isotridecyl alcohol polyoxyethylene ether, CAS No. 9043-30-5, model E-1304, purchased from Taizhou Jiayin Chemical Co., Ltd.;

[0046] Palm oil was purchased from Jinan Qiangxin Chemical Co., Ltd.;

[0047] Polyoxyethylene fatty acid ester (emulsifier LAE-4) was purchased from Sangda Chemical (Nantong) Co., Ltd.

[0048] Embodiment 1-3 provides a water repellent and a preparation method thereof.

[0049] Embodiment 1:

[0050] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of acrylic copolymer, 4 parts of composite emulsifier and 30 parts of deionized water.

[0051] Wherein, the acrylic acid copolymer is prepared by the following method:

[0052] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 2:5:40:20:100, adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 500 r / min, stirring and mixing for 20 minutes until uniform, and stirring and reacting at 30° C. for 3 hours to obtain a modified monomer;

[0053] (2) The ratio of modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 70:5:0.05. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 300 r / min for 20 min. The mixture was heated to 70°C under nitrogen protection for polymerization for 5 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0054] The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 3:1; and the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0055] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:0.8, control the stirring speed to 300r / min, mix the palm oil and deionized water for 20 minutes, add 75% sulfuric acid by mass, heat to 70°C, stir and react for 3 hours, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0056] B. Control the mass ratio of free fatty acid and nickelous oxide to be 70:3, add free fatty acid and nickelous oxide into a reactor together, exclude air, fill with hydrogen until the pressure in the reactor is 5 MPa, then heat to 140° C., react for 4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0057] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 2:1:5, control the stirring speed to 300r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 20 minutes, and then stir and react at 50°C for 4 hours. After the reaction is completed, add deionized water and stir for 20 minutes, then stand for 5 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0058] A method for preparing a water repellent comprises the following steps:

[0059] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0060] S2. Heat deionized water to 50°C, add a composite emulsifier, control the stirring speed to 100 r / min, and stir and mix for 30 minutes until uniform to obtain an emulsion;

[0061] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add acrylic copolymer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0062] Embodiment 2:

[0063] A water repellent comprises the following raw materials in parts by weight: 50 parts of polydimethylsiloxane, 20 parts of isobutyltriethoxysilane, 8 parts of sodium methyl silicate, 10 parts of acrylic copolymer, 6 parts of composite emulsifier and 40 parts of deionized water.

[0064] Wherein, the acrylic acid copolymer is prepared by the following method:

[0065] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 3:4:45:25:100, adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 600 r / min, stirring and mixing for 15 minutes until uniform, stirring and reacting at 35° C. for 2.5 hours, and obtaining a modified monomer;

[0066] (2) The ratio of the modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 75:8:0.08. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 400 r / min for 15 min. The mixture was heated to 75°C under nitrogen protection and the polymerization reaction was carried out for 4 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0067] The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 4:1; and the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0068] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:1, control the stirring speed to 400r / min, mix the palm oil and deionized water for 15 minutes, add 75% sulfuric acid by mass, heat to 75°C, stir and react for 2 hours, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0069] B. Control the mass ratio of free fatty acid and nickelous oxide to 80:4, add free fatty acid and nickelous oxide into a reactor, exclude air, fill with hydrogen until the pressure in the reactor is 5.5 MPa, then heat to 150° C., react for 3 h, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0070] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 3:1:6, control the stirring speed to 400r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 15 minutes, and then stir and react for 3 hours at 60°C. After the reaction is completed, add deionized water and stir for 30 minutes, then stand for 4 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0071] A method for preparing a water repellent comprises the following steps:

[0072] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0073] S2. Heat deionized water to 55°C, add a composite emulsifier, control the stirring speed to 150r / min, and stir and mix for 25min until uniform to obtain an emulsion;

[0074] S3. Add polysiloxane and isobutyl triethoxysilane to the emulsion while stirring. After continuous stirring for 8 minutes, add acrylic copolymer and continue stirring for 25 minutes. Finally, add sodium methyl silicate and stir for 15 minutes. Adjust the pH value of the system to 5.2 to obtain the desired water repellent.

[0075] Embodiment 3:

[0076] A water repellent comprises the following raw materials in parts by weight: 60 parts of polydimethylsiloxane, 25 parts of isobutyltriethoxysilane, 10 parts of sodium methyl silicate, 12 parts of acrylic copolymer, 8 parts of composite emulsifier and 50 parts of deionized water.

[0077] Wherein, the acrylic acid copolymer is prepared by the following method:

[0078] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 5:2:50:30:100, adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 700 r / min, mixing evenly for 10 minutes under stirring, and reacting at 40° C. with stirring for 2 hours to obtain a modified monomer;

[0079] (2) The ratio of the modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 80:10:0.1. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 500 r / min for 10 min. The mixture was heated to 80°C under nitrogen protection for polymerization for 3 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0080] The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 5:1; and the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0081] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:1.2, control the stirring speed to 500r / min, mix the palm oil and deionized water for 10 minutes, add 75% sulfuric acid by mass, heat to 80°C, stir and react for 1 hour, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0082] B. Control the mass ratio of free fatty acid and nickelous oxide to be 90:5, add free fatty acid and nickelous oxide into a reactor together, exclude air, fill with hydrogen until the pressure in the reactor is 6 MPa, then heat to 160° C., react for 2 h, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0083] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 4:1:7, control the stirring speed to 500r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 10 minutes, and then stir and react at 70°C for 2 hours. After the reaction is completed, add deionized water and stir for 40 minutes, then stand for 3 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0084] A method for preparing a water repellent comprises the following steps:

[0085] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0086] S2. Heat deionized water to 60°C, add a composite emulsifier, control the stirring speed to 200r / min, and stir and mix for 20min until uniform to obtain an emulsion;

[0087] S3. Add polysiloxane and isobutyl triethoxysilane to the emulsion while stirring. After continuous stirring for 5 minutes, add acrylic copolymer and continue stirring for 20 minutes. Finally, add sodium methyl silicate and stir for 10 minutes. Adjust the pH value of the system to 4.5 to obtain the desired water repellent.

[0088] In order to verify the performance of the water repellent obtained in Examples 1-3 of the present invention, the present invention sets up Comparative Examples 1-6.

[0089] Comparative Example 1:

[0090] Comparative Example 1 is different from Example 1 only in that, during the preparation of the acrylic copolymer, heptadecafluorodecyltrimethoxysilane is replaced by trifluoropropyltrichlorosilane, as follows:

[0091] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of acrylic copolymer, 4 parts of composite emulsifier and 30 parts of deionized water.

[0092] Wherein, the acrylic acid copolymer is prepared by the following method:

[0093] (1) The mass ratio of trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone was controlled to be 7:40:20:100, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate were added to acetone, the stirring speed was controlled to be 500 r / min, the mixture was stirred for 20 min until uniform, and the mixture was stirred at 30° C. for 3 h to obtain a modified monomer;

[0094] (2) The ratio of modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 70:5:0.05. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 300 r / min for 20 min. The mixture was heated to 70°C under nitrogen protection for polymerization for 5 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0095] The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 3:1; and the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0096] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:0.8, control the stirring speed to 300r / min, mix the palm oil and deionized water for 20 minutes, add 75% sulfuric acid by mass, heat to 70°C, stir and react for 3 hours, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0097] B. Control the mass ratio of free fatty acid and nickelous oxide to be 70:3, add free fatty acid and nickelous oxide into a reactor together, exclude air, fill with hydrogen until the pressure in the reactor is 5 MPa, then heat to 140° C., react for 4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0098] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 2:1:5, control the stirring speed to 300r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 20 minutes, and then stir and react at 50°C for 4 hours. After the reaction is completed, add deionized water and stir for 20 minutes, then stand for 5 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0099] A method for preparing a water repellent comprises the following steps:

[0100] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0101] S2. Heat deionized water to 50°C, add a composite emulsifier, control the stirring speed to 100 r / min, and stir and mix for 30 minutes until uniform to obtain an emulsion;

[0102] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add acrylic copolymer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0103] Comparative Example 2:

[0104] Comparative Example 2 is different from Example 1 only in that, during the preparation of the acrylic copolymer, the mass of trifluoropropyltrichlorosilane is replaced by heptadecafluorodecyltrimethoxysilane, as follows:

[0105] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of acrylic copolymer, 4 parts of composite emulsifier and 30 parts of deionized water.

[0106] Wherein, the acrylic acid copolymer is prepared by the following method:

[0107] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 7:40:20:100, adding heptadecafluorodecyltrimethoxysilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 500 r / min, stirring and mixing for 20 minutes until uniform, stirring and reacting at 30° C. for 3 hours, and obtaining a modified monomer;

[0108] (2) The ratio of modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 70:5:0.05. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 300 r / min for 20 min. The mixture was heated to 70°C under nitrogen protection for polymerization for 5 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0109] The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 3:1; and the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0110] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:0.8, control the stirring speed to 300r / min, mix the palm oil and deionized water for 20 minutes, add 75% sulfuric acid by mass, heat to 70°C, stir and react for 3 hours, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0111] B. Control the mass ratio of free fatty acid and nickelous oxide to be 70:3, add free fatty acid and nickelous oxide into a reactor together, exclude air, fill with hydrogen until the pressure in the reactor is 5 MPa, then heat to 140° C., react for 4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0112] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 2:1:5, control the stirring speed to 300r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 20 minutes, and then stir and react at 50°C for 4 hours. After the reaction is completed, add deionized water and stir for 20 minutes, then stand for 5 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0113] A method for preparing a water repellent comprises the following steps:

[0114] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0115] S2. Heat deionized water to 50°C, add a composite emulsifier, control the stirring speed to 100 r / min, and stir and mix for 30 minutes until uniform to obtain an emulsion;

[0116] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add acrylic copolymer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0117] Comparative Example 3:

[0118] Comparative Example 3 is different from Example 1 only in that the acrylic copolymer is replaced by a modified monomer, as follows:

[0119] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of modified monomer, 4 parts of composite emulsifier and 30 parts of deionized water.

[0120] Wherein, the modified monomer is prepared by the following method:

[0121] The mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone was controlled to be 2:5:40:20:100, and heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate were added to acetone. The stirring speed was controlled to be 500 r / min, and the mixture was stirred for 20 minutes until uniform. The mixture was stirred and reacted at 30° C. for 3 hours to obtain a modified monomer.

[0122] The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 3:1; and the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0123] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:0.8, control the stirring speed to 300r / min, mix the palm oil and deionized water for 20 minutes, add 75% sulfuric acid by mass, heat to 70°C, stir and react for 3 hours, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0124] B. Control the mass ratio of free fatty acid and nickelous oxide to be 70:3, add free fatty acid and nickelous oxide into a reactor together, exclude air, fill with hydrogen until the pressure in the reactor is 5 MPa, then heat to 140° C., react for 4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0125] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 2:1:5, control the stirring speed to 300r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 20 minutes, and then stir and react at 50°C for 4 hours. After the reaction is completed, add deionized water and stir for 20 minutes, then stand for 5 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0126] A method for preparing a water repellent comprises the following steps:

[0127] S1. Weigh the raw materials polysiloxane, isobutyltriethoxysilane, sodium methyl silicate, modified monomer, composite emulsifier and deionized water by weight for later use;

[0128] S2. Heat deionized water to 50°C, add a composite emulsifier, control the stirring speed to 100 r / min, and stir and mix for 30 minutes until uniform to obtain an emulsion;

[0129] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add the modified monomer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0130] Comparative Example 4:

[0131] Comparative Example 4 is different from Example 1 only in that the composite emulsifier is replaced with isomeric tridecanol polyoxyethylene ether, as follows:

[0132] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of acrylic acid copolymer, 4 parts of isomeric tridecanol polyoxyethylene ether and 30 parts of deionized water.

[0133] Wherein, the acrylic acid copolymer is prepared by the following method:

[0134] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 2:5:40:20:100, adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 500 r / min, stirring and mixing for 20 minutes until uniform, and stirring and reacting at 30° C. for 3 hours to obtain a modified monomer;

[0135] (2) The ratio of modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 70:5:0.05. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 300 r / min for 20 min. The mixture was heated to 70°C under nitrogen protection for polymerization for 5 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0136] A method for preparing a water repellent comprises the following steps:

[0137] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic acid copolymer, isomeric tridecanol polyoxyethylene ether and deionized water in parts by weight for later use;

[0138] S2. Heat deionized water to 50° C., add isomeric tridecanol polyoxyethylene ether, control the stirring speed to 100 r / min, and stir and mix for 30 minutes until uniform to obtain an emulsion;

[0139] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add acrylic copolymer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0140] Comparative Example 5:

[0141] Comparative Example 5 is different from Example 1 only in that the composite emulsifier is replaced by epoxidized hydrogenated fatty acid ester, as follows:

[0142] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of acrylic acid copolymer, 4 parts of epoxidized hydrogenated fatty acid ester and 30 parts of deionized water.

[0143] Wherein, the acrylic acid copolymer is prepared by the following method:

[0144] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 2:5:40:20:100, adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 500 r / min, stirring and mixing for 20 minutes until uniform, and stirring and reacting at 30° C. for 3 hours to obtain a modified monomer;

[0145] (2) The ratio of modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 70:5:0.05. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 300 r / min for 20 min. The mixture was heated to 70°C under nitrogen protection for polymerization for 5 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0146] Wherein, the epoxidized hydrogenated fatty acid ester is prepared by the following method:

[0147] A. Control the mass ratio of palm oil, deionized water and sulfuric acid to 100:200:0.8, control the stirring speed to 300r / min, mix the palm oil and deionized water for 20 minutes, add 75% sulfuric acid by mass, heat to 70°C, stir and react for 3 hours, ensure the oil-water phase separation, stand and separate, and obtain free fatty acids;

[0148] B. Control the mass ratio of free fatty acid and nickelous oxide to be 70:3, add free fatty acid and nickelous oxide into a reactor together, exclude air, fill with hydrogen until the pressure in the reactor is 5 MPa, then heat to 140° C., react for 4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid;

[0149] C. Control the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water to 2:1:5, control the stirring speed to 300r / min, stir and mix the hydrogenated fatty acid and epichlorohydrin for 20 minutes, and then stir and react at 50°C for 4 hours. After the reaction is completed, add deionized water and stir for 20 minutes, then stand for 5 hours to separate the layers, remove the water phase, and evaporate to remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

[0150] A method for preparing a water repellent comprises the following steps:

[0151] S1. Weigh the raw materials polysiloxane, isobutyltriethoxysilane, sodium methyl silicate, acrylic acid copolymer, epoxidized hydrogenated fatty acid ester and deionized water in parts by weight for later use;

[0152] S2, heat deionized water to 50°C, add epoxidized hydrogenated fatty acid ester, control the stirring speed to 100r / min, stir and mix for 30min until uniform, and obtain an emulsion;

[0153] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add acrylic copolymer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0154] Comparative Example 6:

[0155] Comparative Example 6 is different from Example 1 only in that the epoxidized hydrogenated fatty acid ester in the composite emulsifier is replaced with a polyoxyethylene fatty acid ester, as follows:

[0156] A water repellent comprises the following raw materials in parts by weight: 40 parts of polydimethylsiloxane, 15 parts of isobutyltriethoxysilane, 5 parts of sodium methyl silicate, 8 parts of acrylic copolymer, 4 parts of composite emulsifier and 30 parts of deionized water.

[0157] Wherein, the acrylic acid copolymer is prepared by the following method:

[0158] (1) Controlling the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and acetone to be 2:5:40:20:100, adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to acetone, controlling the stirring speed to be 500 r / min, stirring and mixing for 20 minutes until uniform, and stirring and reacting at 30° C. for 3 hours to obtain a modified monomer;

[0159] (2) The ratio of modified monomer, dimethacrylate carbamate and potassium persulfate was controlled to be 70:5:0.05. The modified monomer, dimethacrylate carbamate and potassium persulfate were stirred and mixed at a stirring speed of 300 r / min for 20 min. The mixture was heated to 70°C under nitrogen protection for polymerization for 5 h. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and dried in vacuum at 70°C for 5 h to obtain an acrylic copolymer.

[0160] The composite emulsifier includes isomeric tridecanol polyoxyethylene ether and polyoxyethylene fatty acid ester in a mass ratio of 3:1.

[0161] A method for preparing a water repellent comprises the following steps:

[0162] S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use;

[0163] S2. Heat deionized water to 50°C, add a composite emulsifier, control the stirring speed to 100 r / min, and stir and mix for 30 minutes until uniform to obtain an emulsion;

[0164] S3. Add polysiloxane and isobutyltriethoxysilane to the emulsion while stirring. After continuous stirring for 10 minutes, add acrylic copolymer and continue stirring for 30 minutes. Finally, add sodium methyl silicate and stir for 20 minutes. Adjust the pH value of the system to 6.0 to obtain the desired water repellent.

[0165] Performance testing:

[0166] The properties of the water repellents in Examples 1-3 of the present invention and Comparative Examples 1-6 were tested respectively, as follows:

[0167] Preparation of cement foam insulation board sample: Weigh 80 parts by weight of 42.5 grade ordinary Portland cement, 5 parts by weight of 200 mesh hard gypsum powder, and 5 parts by weight of 200 mesh first-grade fly ash, stir and mix evenly, then add 35 parts by weight of 45°C hot water, stir and mix evenly, then add 1.2 parts by weight of hydrogen peroxide, stir at 700r / min for 12 seconds, and pour into a mold with a size of 30cm×30cm×30cm. After the gasification is completed, cure with the mold for 1 day, then remove the mold, cut into a size of 10cm×10cm×10cm, wrap it with a film and cure it for 28 days, then place it in an oven at 80°C and dry it to constant weight to obtain the cement foam insulation board sample.

[0168] Control the total spraying amount to 150g / m 2 , respectively, spray the water repellent in Examples 1-3 of the present invention and Comparative Examples 1-6 on the surface of the cement foam insulation board sample three times, each time interval is 15 minutes, after spraying, stand for 24 hours, and then obtain the water repellent test sample;

[0169] Hydrophobic angle: The contact angle of the surface of different hydrophobic test samples was measured using an optical contact angle meter (DSA30). The drop size was 5 μL each time, and the contact angle was measured.

[0170] Abrasion resistance: Use 600-grit sandpaper to place on the hydrophobic test sample, place a 100g weight on the sandpaper, drag the sandpaper for 10 cm, repeat 50 times, and measure the contact angle after friction.

[0171] Water absorption: stick the caston tube on the hydrophobic test sample and fill it with water for 24 hours to measure the water absorption;

[0172] Aging resistance: The hydrophobic test samples were placed in a UV aging test chamber for 168 hours of aging treatment. The UV aging used a xenon lamp with a power of 35W. After the treatment, the hydrophobic test samples were taken out and the same water absorption test was performed;

[0173] The results are shown in Table 1 below.

[0174] Table 1:

[0175] .

[0176] In addition, the applicant soaked the cement foam insulation board sample in water for 30 minutes, took it out, and placed it at room temperature for 24 hours until the surface water evaporated, and then sprayed the water repellent prepared in Example 1 of the present invention, and controlled the total spraying amount to be 150g / m 2, sprayed on the surface of the cement foam insulation board sample three times, each time with an interval of 15 minutes. After the spraying is completed, let it stand for 24 hours to obtain the sample to be tested for the heated moisture volatilization test, and record the initial weight as 588g; put the sample to be tested for the heated moisture volatilization test in a drying oven at 50℃, and record the sample weight as 517g after heating for 24h, and record the sample weight as 486g after continuing to heat for 24h, and record the sample weight as 475g after continuing to heat for 24h.

[0177] Combining the above Table 1 and the data shown in the heating water volatilization test, it can be seen that the comprehensive performance of the water repellent prepared in Examples 1-3 of the present invention is significantly better than that of Comparative Examples 1-6. The water repellent prepared in the embodiments of the present invention is coated on the surface of the cement foam insulation board, cement foam insulation board or block, and has good bonding and waterproof properties. While being waterproof, it does not affect the discharge of moisture inside the cement foam insulation board or block to the outside, and has broad application prospects.

[0178] Figure 1 This is a diagram showing the effect of the hydrophobic test sample in Example 1 of the present invention not absorbing water after being dripped with water for 24 hours.

[0179] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A water repellent, characterized in that: The method comprises the following raw materials in parts by weight: 40-60 parts of polysiloxane, 15-25 parts of isobutyl triethoxysilane, 5-10 parts of sodium methyl silicate, 8-12 parts of acrylic copolymer, 4-8 parts of composite emulsifier, and 30-50 parts of deionized water; The acrylic acid copolymer is prepared by the following method: (1) adding heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate and 2-hydroxyethyl acrylate to a solvent, mixing them evenly under stirring, and reacting them at 30-40° C. for 2-3 hours to obtain a modified monomer; (2) The modified monomer, dimethacrylate urethane and initiator are mixed uniformly under stirring, heated to 70-80°C under protective gas, and polymerized for 3-5 hours. After the reaction is completed, the temperature is lowered, the mixture is concentrated under reduced pressure, and vacuum dried to obtain an acrylic copolymer; The composite emulsifier comprises isomeric tridecanol polyoxyethylene ether and epoxidized hydrogenated fatty acid ester in a mass ratio of 3-5:

1.

2. The water repellent according to claim 1, characterized in that The invention comprises the following raw materials in parts by weight: 50 parts of polysiloxane, 20 parts of isobutyl triethoxy silane, 8 parts of sodium methyl silicate, 10 parts of acrylic copolymer, 6 parts of composite emulsifier and 40 parts of deionized water.

3. The water repellent according to claim 1, characterized in that: In the step (1), the mass ratio of heptadecafluorodecyltrimethoxysilane, trifluoropropyltrichlorosilane, methyl methacrylate, 2-hydroxyethyl acrylate and solvent is 2-5:2-5:40-50:20-30:

100.

4. The water repellent according to claim 1, characterized in that In the step (2), the ratio of the modified monomer, dimethacrylate urethane and initiator is 70-80:5-10:0.05-0.

1.

5. The water repellent according to claim 1, characterized in that: The epoxidized hydrogenated fatty acid ester is prepared by the following method: A. After mixing vegetable oil with deionized water, add an acid catalyst, heat to 70-80°C, stir and react for 1-3 hours, ensure that the oil and water phases are separated, and stand to separate the layers to obtain free fatty acids; B. Add free fatty acid and nickel catalyst into a reactor, exclude air, fill with hydrogen until the pressure in the reactor is 5-6 MPa, then heat to 140-160° C., react for 2-4 hours, and after the reaction is completed, cool the reactor, separate the nickel catalyst, and obtain hydrogenated fatty acid; C. Mix the hydrogenated fatty acid and epichlorohydrin, stir and react at 50-70°C for 2-4 hours. After the reaction is completed, add deionized water and stir evenly, let it stand and separate into layers. After removing the aqueous phase, evaporate and remove the solvent to obtain epoxidized hydrogenated fatty acid ester.

6. The water repellent according to claim 5, characterized in that: In step A, the vegetable oil is soybean oil or palm oil; the acid catalyst is sulfuric acid; and the mass ratio of the vegetable oil, deionized water, and acid catalyst is 100:200:0.8-1.

2.

7. The water repellent according to claim 5, characterized in that The mass ratio of free fatty acid to nickel catalyst in step B is 70-90:3-5; the mass ratio of hydrogenated fatty acid, epichlorohydrin and deionized water in step C is 2-4:1:5-7.

8. A method for preparing a water repellent according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Weigh the raw materials polysiloxane, isobutyl triethoxysilane, sodium methyl silicate, acrylic copolymer, composite emulsifier and deionized water by weight for later use; S2, heating deionized water to 50-60°C, adding composite emulsifier and stirring evenly to obtain emulsion; S3. Add polysiloxane and isobutyl triethoxysilane to the emulsion while stirring, continue stirring for 5-10 minutes, add acrylic copolymer and continue stirring for 20-30 minutes, finally add sodium methyl silicate and stir for 10-20 minutes, adjust the pH value of the system to 4.5-6.0, and obtain the desired water repellent.

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