Polyurethane modified organic silicon fluoride-free waterproof agent and preparation method thereof

Abstract

The invention relates to the technical field of fabric waterproofing agents, in particular to a polyurethane modified organic silicon fluoride-free waterproofing agent and a preparation method thereof. The polyurethane modified organic silicon fluoride-free waterproof agent is prepared from the following raw materials in parts by mass: 5 to 15 parts of hexamethylene diisocyanate, 5 to 15 parts of butyl acrylate, 1 to 5 parts of methyl methacrylate, 40 to 60 parts of octamethylcyclotetrasiloxane, 10 to 30 parts of alpha, omega-dihydroxy polydimethylsiloxane and 5 to 10 parts of gamma-aminopropyl methyl diethoxy silane. The invention relates to a silane coupling agent, which is prepared from the following raw materials in parts by weight: 1 to 5 parts of glycidyl ether oxypropyl trimethoxy silane, 0.1 to 1 part of tetramethylammonium hydroxide, 0.1 to 1 part of triethylamine, 2 to 5 parts of tetraethoxysilane, 0.2 to 0.75 part of ammonia, 0.1 to 1 part of silane coupling agent KH-570, 0.01 to 0.1 part of dibutyltin dilaurate, 1 to 5 parts of epsilon-caprolactam, 1 to 2 parts of emulsifier and 0.1 to 1 part of initiator. The fabric treated by the method has good softness and excellent hydrophobic effect.

Description

Technical Field

[0001] The present invention relates to the technical field of fabric waterproofing agents, in particular to a polyurethane modified organosilicon fluorine-free waterproofing agent and a preparation method thereof. Background Art

[0002] Waterproofing textiles is a key process for imparting hydrophobic properties to fabrics, directly impacting their application scope and market value. Traditional fluorinated water repellents have long dominated the market due to their excellent water resistance and durability. However, the fluorinated raw materials used in their production process pose serious environmental and health risks. Fluoride emissions lead to soil and water pollution through fluoride-containing wastewater. Furthermore, fluorinated substances are difficult to degrade, with a half-life of decades, and can cause hepatotoxicity and reproductive toxicity through bioaccumulation.

[0003] Currently, the mainstream development trend is the use of fluorine-free water repellents. In recent years, the textile printing and dyeing industry has seen increasing demand for high-end fluorine-free water repellents. However, existing fluorine-free water repellents present drawbacks that plague dyeing and finishing companies. First, while silicone water repellents (such as polydimethylsiloxane) impart a soft feel to fabrics, they suffer from poor washability. Second, these products rely on cross-linking agents (such as melamine resin) or increase the amount of water repellent to improve durability. However, excessive cross-linking can increase fabric hardness by 30-50%, and cross-linking agents are prone to formaldehyde release. This hand-impairing effect is often addressed through the use of softeners, which generally results in a decrease in water repellency.

[0004] The present invention aims to develop a method for synthesizing a polyurethane-modified organosilicon fluorine-free waterproofing agent, which can provide a soft feel, better waterproof effect and durability, so as to overcome the shortcomings of the prior art. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a polyurethane modified organosilicon fluorine-free waterproofing agent and a preparation method thereof.

[0006] A polyurethane-modified organic silicon fluorine-free waterproofing agent comprises the following raw materials in parts by mass: 5-15 parts of hexamethylene diisocyanate, 5-15 parts of butyl acrylate, 1-5 parts of methyl methacrylate, 40-60 parts of octamethylcyclotetrasiloxane, 10-30 parts of α,ω-dihydroxypolydimethylsiloxane, 5-10 parts of γ-aminopropylmethyldiethoxysilane, 1-5 parts of glycidyloxypropyltrimethoxysilane, 0.1-1 part of tetramethylammonium hydroxide, 0.1-1 part of triethylamine, 2-5 parts of tetraethyl orthosilicate, 0.2-0.75 part of ammonia, 0.1-1 part of silane coupling agent KH-570, 0.01-0.1 part of dibutyltin dilaurate, 1-5 parts of ε-caprolactam, 1-2 parts of emulsifier, and 0.1-1 part of initiator.

[0007] Preferably, the hydroxyl content of α,ω-dihydroxypolydimethylsiloxane is 4-5%.

[0008] Preferably, the emulsifier includes: sodium dodecyl sulfate, polyoxyethylene dodecyl phenyl ether.

[0009] Preferably, the mass ratio of sodium dodecyl sulfate to polyoxyethylene dodecyl phenyl ether is 1:2-4.

[0010] Preferably, the initiator is persulfate, specifically ammonium persulfate.

[0011] The preparation method of the above polyurethane-modified silicone fluorine-free water repellent includes the following steps: S1. Mix octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and toluene evenly, heat up to 80-90 °C under nitrogen protection, dropwise add tetramethylammonium hydroxide under stirring, keep warm for 4-6 h, and remove toluene by vacuum distillation to obtain a silicone prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and isopropanol, react at 40-50 °C for 3-5 h, remove isopropanol and methanol to obtain a silicone intermediate; S3. Add tetraethyl orthosilicate to anhydrous ethanol and mix evenly, dropwise add ammonia water to it under stirring, react at 50-60 °C for 1-2 h, add silane coupling agent KH-570, stir at 70-80 °C for 1-2 h, centrifuge, wash, and vacuum dry to obtain silica powder; S4. Mix the silicone prepolymer, silicone intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, pre-react at 60-70 °C for 2-3 h; heat up to 75-80 °C and continue to react, add ε-caprolactam, react at 100-110 °C for 1-2 h, and remove low-boiling substances by vacuum distillation to obtain a block copolymer; S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to water and stir evenly, heat up to 60-70 °C, dropwise add the initiator to it under stirring, react for 4-6 h, cool to 30-40 °C, and adjust the pH value of the system to 6.5-7.

[0012] Preferably, the particle size of the silica powder obtained in S3 is 100-300 nm.

[0013] Preferably, in S4, when the NCO group conversion rate reaches 50-60% during the pre-reaction, heat up to 75-80 °C.

[0014] Preferably, in S5, ammonia water is used to adjust the pH value of the system to 6.5-7.

[0015] Preferably, the particle size of the polyurethane-modified silicone fluorine-free water repellent obtained in S5 is 80 - 120 nm, and the solid content is 30 - 35%.

[0016] Beneficial effects: Although traditional silicone water repellents can endow fabrics with a soft handfeel, they lack reactive groups, resulting in weak binding force with fibers and being easily eluted.

[0017] In the present invention, hexamethylene diisocyanate is used to block and connect amino silicone and hydroxy silicone to form an "alternating soft segment - hard segment" structure; among them, the polydimethylsiloxane soft segment ensures the flexibility of the molecular chain, and the handfeel score of the finished cotton fabric can reach 4.5; while the urea bonds in the hard segment can form hydrogen bonds with cellulose hydroxyl groups and polyester carboxyl groups, and the binding effect is significantly enhanced.

[0018] In the present invention, ε-caprolactam is introduced to block the hexamethylene diisocyanate group, which can be deblocked and release the NCO group during fabric drying or baking, enabling it to react with fiber active groups, further enhancing the binding stability. At the same time, after being blocked by ε-caprolactam, it can effectively avoid the storage instability problem caused by free NCO, increasing the storage stability.

[0019] In the emulsion polymerization process of the present invention, silica powder is added as a nucleating agent. Among them, the α,β-unsaturated double bonds participate in the free radical reaction in the emulsion polymerization, enabling the silica particles to be embedded in the polyurethane-silicone / acrylate network through covalent bonds, avoiding particle shedding, and forming "silicone-polyurethane / silica" composite microparticles, which can effectively construct a rough structure. Combined with the low surface energy provided by silicone, the hydrophobic effect is excellent, and good softness can be maintained. In the present invention, the side chain of amino silicone can be combined with cotton fibers through electrostatic adsorption, the hydroxy silicone chain segment forms van der Waals forces with the ester groups of polyester, and the polyurethane hard segment can adapt to the amide bonds of nylon, enabling stable combination of polyester, cotton, and nylon, and greatly improving the selectivity for fabrics. Description of the drawings

[0020] Figure 1 It is a comparison diagram of the original water contact angle of untreated cotton fabric and cotton fabric finished with the water repellent obtained in Example 5 or Comparative Examples 1 - 2 and the water contact angle after 10 washes.

[0021] Figure 2 It is a comparison diagram of the original water contact angle of untreated nylon fabric and nylon fabric finished with the water repellent obtained in Example 5 or Comparative Examples 1 - 2 and the water contact angle after 10 washes.

[0022] Figure 3 It is a comparison diagram of the original water contact angle of untreated polyester fabric and polyester fabric finished with the water repellent obtained in Example 5 or Comparative Examples 1 - 2 and the water contact angle after 10 washes.

[0023] Figure 4 It is a comparison chart of the bending stiffness of the untreated fabric and the fabric treated with the waterproofing agent obtained in Example 5 or Comparative Examples 1-2.

[0024] Figure 5 It is a comparison chart of the handle score of the fabric treated with the waterproofing agent obtained in Example 5 or Comparative Examples 1-2. Detailed implementation manners

[0025] The present invention will be further explained below in conjunction with specific embodiments.

[0026] The hydroxyl content of the α,ω-dihydroxypolydimethylsiloxane used below is 4.2%.

[0027] Example 1 A polyurethane-modified silicone fluorine-free waterproofing agent, the raw materials thereof comprising: 400 g of octamethylcyclotetrasiloxane, 100 g of α,ω-dihydroxypolydimethylsiloxane, 50 g of γ-aminopropylmethyldiethoxysilane, 10 g of glycidyl ether oxypropyltrimethoxysilane, 1 g of tetramethylammonium hydroxide, 1 g of triethylamine, 20 g of tetraethyl orthosilicate, 2 g of ammonia, 1 g of silane coupling agent KH-570, 50 g of hexamethylene diisocyanate, 0.1 g of dibutyltin dilaurate, 10 g of ε-caprolactam, 50 g of butyl acrylate, 10 g of methyl methacrylate, 10 g of emulsifier, 1 g of ammonium persulfate.

[0028] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene lauryl ether in a mass ratio of 1:2.

[0029] The preparation method of the above polyurethane-modified silicone fluorine-free waterproofing agent comprises the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 200 g of toluene to a reaction kettle, heat to 80 °C under nitrogen protection, dropwise add tetramethylammonium hydroxide under stirring, keep warm for 4 h, and remove toluene by vacuum distillation to obtain a silicone prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 150 g of isopropanol, react at 40 °C for 3 h, remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain a silicone intermediate; S3. Add tetraethyl orthosilicate to 200 g of absolute ethanol and mix evenly. While stirring, dropwise add 10 g of 20% ammonia water, react at 50 °C for 1 h, add silane coupling agent KH-570, stir at 70 °C for 1 h, centrifuge, wash once with ethanol, and vacuum dry to obtain silica powder; S4. Mix the organosilicon prepolymer, organosilicon intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and carry out a pre-reaction at a temperature of 60°C; when the NCO group conversion rate is monitored to reach 50%, raise the temperature to 75°C and continue the reaction until the NCO conversion rate reaches 90%. Then add ε-caprolactam and react at a temperature of 100°C for 1 h. Remove the low-boiling substances by vacuum distillation to obtain the block copolymer; S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 1000 g of deionized water, stir evenly, raise the temperature to 60°C, and dropwise add ammonium persulfate thereto under stirring. React for 4 h, cool to 30°C, and adjust the pH value of the system to 6.5 - 7 with ammonia water.

[0030] Example 2 A polyurethane-modified organosilicon fluorine-free water repellent, the raw materials of which include: 600 g of octamethylcyclotetrasiloxane, 300 g of α,ω-dihydroxypolydimethylsiloxane, 100 g of γ-aminopropylmethyldiethoxysilane, 50 g of glycidyl ether oxypropyltrimethoxysilane, 10 g of tetramethylammonium hydroxide, 10 g of triethylamine, 50 g of tetraethyl orthosilicate, 7.5 g of ammonia, 10 g of silane coupling agent KH-570, 150 g of hexamethylene diisocyanate, 1 g of dibutyltin dilaurate, 50 g of ε-caprolactam, 150 g of butyl acrylate, 50 g of methyl methacrylate, 20 g of emulsifier, and 10 g of ammonium persulfate.

[0031] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene lauryl ether in a mass ratio of 1:4.

[0032] The preparation method of the above polyurethane-modified organosilicon fluorine-free water repellent includes the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 300 g of toluene to the reaction kettle, raise the temperature to 90°C under nitrogen protection, dropwise add tetramethylammonium hydroxide under stirring, keep warm for 6 h, and remove toluene by vacuum distillation to obtain the organosilicon prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 250 g of isopropanol, react at a temperature of 50°C for 5 h, remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain the organosilicon intermediate; S3. Add tetraethyl orthosilicate to 300 g of absolute ethanol and mix evenly. Dropwise add 30 g of 25% ammonia water thereto under stirring, react at a temperature of 60°C for 2 h, add silane coupling agent KH-570, stir at a temperature of 80°C for 2 h, centrifuge, wash with ethanol 3 times, and vacuum dry to obtain the silica powder; S4. Mix the organosilicon prepolymer, organosilicon intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and pre-react at 70°C for 3 h; when the NCO group conversion rate is monitored to reach 60%, raise the temperature to 80°C and continue the reaction until the NCO conversion rate reaches 95%. Then add ε-caprolactam and react at 110°C for 2 h. Remove the low-boiling substances by vacuum distillation to obtain the block copolymer. S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 2000 g of deionized water and stir evenly. Raise the temperature to 70°C, and while stirring, dropwise add ammonium persulfate to it. React for 6 h, cool to 40°C, and adjust the pH value of the system to 6.5 - 7 with ammonia water.

[0033] Example 3 A polyurethane-modified organosilicon fluorine-free waterproofing agent, the raw materials of which include: 450 g of octamethylcyclotetrasiloxane, 250 g of α,ω-dihydroxypolydimethylsiloxane, 70 g of γ-aminopropylmethyldiethoxysilane, 40 g of glycidyl ether oxypropyltrimethoxysilane, 2 g of tetramethylammonium hydroxide, 7 g of triethylamine, 30 g of tetraethyl orthosilicate, 5.25 g of ammonia, 7 g of silane coupling agent KH-570, 80 g of hexamethylene diisocyanate, 0.7 g of dibutyltin dilaurate, 20 g of ε-caprolactam, 120 g of butyl acrylate, 20 g of methyl methacrylate, 17 g of emulsifier, and 3 g of ammonium persulfate.

[0034] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene lauryl ether in a mass ratio of 1:3.5.

[0035] The preparation method of the above polyurethane-modified organosilicon fluorine-free waterproofing agent includes the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 220 g of toluene to the reaction kettle, raise the temperature to 88°C under nitrogen protection, and while stirring, dropwise add tetramethylammonium hydroxide. Keep the temperature for 4.5 h, and remove toluene by vacuum distillation to obtain the organosilicon prepolymer. S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 220 g of isopropanol, and react at 42°C for 4.5 h. Remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain the organosilicon intermediate. S3. Add tetraethyl orthosilicate to 220 g of absolute ethanol and mix evenly. While stirring, dropwise add 25 g of 21% ammonia water to it, react at 58°C for 80 min, add silane coupling agent KH-570, stir at 77°C for 80 min, centrifuge, wash twice with ethanol, and vacuum dry to obtain the silica powder. S4. Mix the organosilicon prepolymer, organosilicon intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and perform a pre-reaction at a temperature of 68°C; when monitoring that the conversion rate of the NCO group reaches 50%, raise the temperature to 79°C and continue the reaction until the NCO conversion rate reaches 90%. Then add ε-caprolactam and react at a temperature of 103°C for 80 min. Remove the low-boiling substances by vacuum distillation to obtain the block copolymer.

[0036] S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 1800 g of deionized water and stir evenly. Raise the temperature to 62°C, and while stirring, dropwise add ammonium persulfate thereto. React for 5.5 h, cool to 33°C, and adjust the pH value of the system to 6.5 - 7 with ammonia water.

[0037] Example 4 A polyurethane-modified organosilicon fluorine-free waterproofing agent, the raw materials of which include: 550 g of octamethylcyclotetrasiloxane, 150 g of α,ω-dihydroxypolydimethylsiloxane, 90 g of γ-aminopropylmethyldiethoxysilane, 20 g of glycidyl ether oxypropyltrimethoxysilane, 8 g of tetramethylammonium hydroxide, 3 g of triethylamine, 40 g of tetraethyl orthosilicate, 3.45 g of ammonia, 3 g of silane coupling agent KH-570, 120 g of hexamethylene diisocyanate, 0.3 g of dibutyltin dilaurate, 40 g of ε-caprolactam, 80 g of butyl acrylate, 40 g of methyl methacrylate, 13 g of emulsifier, and 7 g of ammonium persulfate.

[0038] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene lauryl ether in a mass ratio of 1:2.5.

[0039] The preparation method of the above polyurethane-modified organosilicon fluorine-free waterproofing agent includes the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 280 g of toluene to the reaction kettle, raise the temperature to 82°C under nitrogen protection, dropwise add tetramethylammonium hydroxide while stirring, keep warm for 5.5 h, and remove toluene by vacuum distillation to obtain the organosilicon prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 180 g of isopropanol, react at a temperature of 48°C for 3.5 h, remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain the organosilicon intermediate; S3. Add tetraethyl orthosilicate to 280 g of absolute ethanol and mix evenly. While stirring, dropwise add 15 g of ammonia water with a mass fraction of 23% thereto, react at a temperature of 52°C for 100 min, add silane coupling agent KH-570, stir at a temperature of 72°C for 100 min, centrifuge, wash twice with ethanol, and vacuum dry to obtain the silica powder; S4. Mix the organosilicon prepolymer, organosilicon intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and pre-react at 62°C; when monitoring the NCO group conversion rate reaches 60%, raise the temperature to 77°C and continue to react until the NCO conversion rate reaches 95%. Add ε-caprolactam and react at 107°C for 100 min. Remove the low-boiling substances by vacuum distillation to obtain the block copolymer. S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 1200 g of deionized water and stir evenly. Raise the temperature to 68°C, and dropwise add ammonium persulfate thereto under stirring. React for 4.5 h, cool to 37°C, and adjust the pH value of the system to 6.5 - 7 with ammonia water.

[0040] Example 5 A polyurethane-modified organosilicon fluorine-free waterproofing agent, the raw materials of which include: 500 g of octamethylcyclotetrasiloxane, 200 g of α,ω-dihydroxypolydimethylsiloxane, 80 g of γ-aminopropylmethyldiethoxysilane, 30 g of glycidyl ether oxypropyltrimethoxysilane, 5 g of tetramethylammonium hydroxide, 5 g of triethylamine, 35 g of tetraethyl orthosilicate, 4.4 g of ammonia, 5 g of silane coupling agent KH-570, 100 g of hexamethylene diisocyanate, 0.5 g of dibutyltin dilaurate, 30 g of ε-caprolactam, 100 g of butyl acrylate, 30 g of methyl methacrylate, 15 g of emulsifier, and 5 g of ammonium persulfate.

[0041] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene dodecyl phenyl ether in a mass ratio of 1:3.

[0042] The preparation method of the above polyurethane-modified organosilicon fluorine-free waterproofing agent includes the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 250 g of toluene to the reaction kettle, raise the temperature to 85°C under nitrogen protection, dropwise add tetramethylammonium hydroxide under stirring, keep warm for 5 h, and remove toluene by vacuum distillation to obtain the organosilicon prepolymer. S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 200 g of isopropanol, react at 45°C for 4 h, remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain the organosilicon intermediate. S3. Add tetraethyl orthosilicate to 250 g of absolute ethanol and mix evenly. Dropwise add 20 g of 22% ammonia water thereto under stirring, react at 55°C for 90 min, add silane coupling agent KH-570, stir at 75°C for 90 min, centrifuge, wash with ethanol twice, and vacuum dry to obtain the silica powder. S4. Mix the silicone prepolymer, silicone intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and pre-react at a temperature of 65°C; when the NCO group conversion rate is monitored to reach 55%, raise the temperature to 78°C and continue the reaction until the NCO conversion rate reaches 93%. Add ε-caprolactam and react at a temperature of 105°C for 90 minutes. Remove the low-boiling substances by vacuum distillation to obtain the block copolymer; S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 1500 g of deionized water and stir evenly. Raise the temperature to 65°C, and while stirring, dropwise add ammonium persulfate thereto. React for 5 hours, cool to 35°C, and adjust the pH value of the system to 6.5 - 7 using ammonia water.

[0043] Comparative Example 1 A polyurethane-modified silicone fluorine-free waterproofing agent, the raw materials of which include: 500 g of octamethylcyclotetrasiloxane, 200 g of α,ω-dihydroxypolydimethylsiloxane, 80 g of γ-aminopropylmethyldiethoxysilane, 30 g of glycidyl ether oxypropyltrimethoxysilane, 5 g of tetramethylammonium hydroxide, 5 g of triethylamine, 40 g of tetraethyl orthosilicate, 4.4 g of ammonia, 100 g of hexamethylene diisocyanate, 0.5 g of dibutyltin dilaurate, 30 g of ε-caprolactam, 100 g of butyl acrylate, 30 g of methyl methacrylate, 15 g of emulsifier, and 5 g of ammonium persulfate.

[0044] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene lauryl phenol ether in a mass ratio of 1:3.

[0045] The preparation method of the above polyurethane-modified silicone fluorine-free waterproofing agent includes the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 250 g of toluene to the reaction kettle, raise the temperature to 85°C under nitrogen protection, dropwise add tetramethylammonium hydroxide while stirring, keep warm for 5 hours, and remove toluene by vacuum distillation to obtain the silicone prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 200 g of isopropanol, react at a temperature of 45°C for 4 hours, remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain the silicone intermediate; S3. Add tetraethyl orthosilicate to 250 g of absolute ethanol and mix evenly. While stirring, dropwise add 20 g of 22% ammonia water thereto, react at a temperature of 55°C for 90 minutes, centrifuge, wash twice with ethanol, and vacuum dry to obtain the silica powder; S4. Mix the silicone prepolymer, silicone intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and pre-react at a temperature of 65°C; when monitoring the NCO group conversion rate reaches 55%, raise the temperature to 78°C and continue the reaction until the NCO conversion rate reaches 93%. Add ε-caprolactam and react at a temperature of 105°C for 90 min. Remove the low-boiling substances by vacuum distillation to obtain the block copolymer; S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 1500 g of deionized water and stir evenly. Raise the temperature to 65°C, and dropwise add ammonium persulfate thereto under stirring. React for 5 h, cool to 35°C, and adjust the pH value of the system to 6.5 - 7 using ammonia water.

[0046] Comparative Example 2 A polyurethane-modified silicone fluorine-free water repellent, the raw materials of which include: 500 g of octamethylcyclotetrasiloxane, 200 g of α,ω-dihydroxypolydimethylsiloxane, 80 g of γ-aminopropylmethyldiethoxysilane, 30 g of glycidyl ether oxypropyltrimethoxysilane, 5 g of tetramethylammonium hydroxide, 5 g of triethylamine, 35 g of tetraethyl orthosilicate, 4.4 g of ammonia, 5 g of silane coupling agent KH-570, 100 g of hexamethylene diisocyanate, 0.5 g of dibutyltin dilaurate, 100 g of butyl acrylate, 30 g of methyl methacrylate, 15 g of emulsifier, and 5 g of ammonium persulfate.

[0047] The emulsifier is composed of sodium dodecyl sulfate and polyoxyethylene lauryl ether in a mass ratio of 1:3.

[0048] The preparation method of the above polyurethane-modified silicone fluorine-free water repellent includes the following steps: S1. Add octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and 250 g of toluene to the reaction kettle, raise the temperature to 85°C under nitrogen protection, dropwise add tetramethylammonium hydroxide under stirring, keep warm for 5 h, and remove toluene by vacuum distillation to obtain the silicone prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and 200 g of isopropanol, react at a temperature of 45°C for 4 h, remove the generated methanol through a fractionation device, and remove isopropanol and residual methanol by vacuum distillation to obtain the silicone intermediate; S3. Add tetraethyl orthosilicate to 250 g of absolute ethanol and mix evenly. Dropwise add 20 g of 22% ammonia water thereto under stirring, react at a temperature of 55°C for 90 min, add silane coupling agent KH-570, stir at a temperature of 75°C for 90 min, centrifuge, wash twice with ethanol, and vacuum dry to obtain the silica powder; S4. Mix the silicone prepolymer, silicone intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, and pre-react at a temperature of 65°C; monitor the conversion rate of the NCO group until it reaches 95%, and remove the low-boiling substances by vacuum distillation to obtain a block copolymer; S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to 1500 g of deionized water, stir evenly, heat up to 65°C, and dropwise add ammonium persulfate thereto under stirring. React for 5 h, cool to 35°C, and adjust the pH value of the system to 6.5 - 7 with ammonia water.

[0049] Use a laser particle size analyzer to detect the particle size distribution of the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 and Comparative Examples 1 - 2. The solid content range of all three is within 30 - 35%, and the average particle size is 100 ± 10 nm.

[0050] Store the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 and Comparative Examples 1 - 2 at room temperature for 12 months. It is found that the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 does not delaminate after 12 months of storage at room temperature, while the polyurethane-modified silicone fluorine-free water repellent obtained in Comparative Example 1 delaminates after 12 months of storage at room temperature, and the polyurethane-modified silicone fluorine-free water repellent obtained in Comparative Example 2 delaminates only after 6 months of storage at room temperature.

[0051] Dilute the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 and Comparative Examples 1 - 2 with water to a solid content of 10%; dip and roll the woven fabrics (specifically cotton fabrics, nylon fabrics, and polyester fabrics) in each group of diluted water repellents, dry at 100°C, heat-treat at 150°C for 60 s, and cool to room temperature. Take samples from each group for static water contact angle detection, and then detect the static water contact angle again after washing 10 times to characterize the waterproof effect and wash resistance.

[0052] As Figures 1 to 3 shown, the water repellents obtained in Example 5 and Comparative Examples 1 - 2 can effectively increase the water contact angle of the untreated fabrics and improve the waterproof ability of the fabrics. Even after washing 10 times, their water contact angles are still higher than those of the untreated fabrics; the original water contact angle of the fabrics finished with the water repellent obtained in Example 5 is slightly higher than that of Comparative Example 2 (P > 0.05), but both are significantly higher than that of Comparative Example 1 (P < 0.05); after washing 10 times, the water contact angle of the fabrics finished with the water repellent obtained in Example 5 is significantly higher than that of Comparative Examples 1 - 2 (P < 0.05). It is confirmed that the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 has the best waterproof effect and wash resistance.

[0053] Determine the bending stiffness of the fabrics finished with the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 and Comparative Examples 1 - 2 according to ISO 2493-1:2020. AsFigure 4 As shown, the bending stiffness of the fabric finished with the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 was the smallest, superior to Comparative Examples 1-2 (P < 0.05).

[0054] Thirty persons (half male and half female) were randomly selected to evaluate the softness of the experimental specimens by feeling them with their hands. In a constant temperature and humidity chamber, with the un-finished fabric as the reference, the softness was recorded as 0 and evaluated on a 5-point scale, where a higher score indicates a higher softness. The scores of the 30 persons were averaged to obtain the subjective evaluation of the fabric handle.

[0055] As Figure 5 shown, the fabric finished with the polyurethane-modified silicone fluorine-free water repellent obtained in Example 5 had the highest handle score, superior to Comparative Examples 1-2 (P < 0.05).

[0056] The applicant believes that: This is because in the present invention, hexamethylene diisocyanate is used to block-connect amino silicone and hydroxy silicone to form an "alternating structure of soft segment - hard segment"; among them, the polydimethylsiloxane soft segment ensures the flexibility of the molecular chain; and the urea bonds in the hard segment can form hydrogen bonds with cellulose hydroxyl groups and polyester carboxyl groups, significantly enhancing the binding effect; and ε-caprolactam is introduced in the present invention to block the hexamethylene diisocyanate group, which can release the NCO group by de-blocking during the drying or baking of the fabric, enabling it to react with the fiber active groups, further enhancing the binding stability. At the same time, after being blocked by ε-caprolactam, it can effectively avoid the storage instability problem caused by free NCO, increasing the storage stability. At the same time, during the emulsion polymerization process of the present invention, silica powder is added as a nucleating agent, and the α,β-unsaturated double bonds participate in the free radical reaction during the emulsion polymerization, enabling the silica particles to be embedded in the polyurethane-silicone / acrylate network through covalent bonds, avoiding particle shedding, forming "silicone-polyurethane / silica" composite microparticles, which can effectively construct a rough structure, cooperate with the low surface energy provided by the silicone, have excellent hydrophobic effects, and can maintain good softness.

[0057] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A polyurethane-modified silicone fluorine-free waterproofing agent, characterized in that, Its raw materials by mass parts include: 5-15 parts of hexamethylene diisocyanate, 5-15 parts of butyl acrylate, 1-5 parts of methyl methacrylate, 40-60 parts of octamethylcyclotetrasiloxane, 10-30 parts of α,ω-dihydroxypolydimethylsiloxane, 5-10 parts of γ-aminopropylmethyldiethoxysilane, 1-5 parts of glycidyl ether oxypropyltrimethoxysilane, 0.1-1 part of tetramethylammonium hydroxide, 0.1-1 part of triethylamine, 2-5 parts of tetraethyl orthosilicate, 0.2-0.75 part of ammonia, 0.1-1 part of silane coupling agent KH-570, 0.01-0.1 part of dibutyltin dilaurate, 1-5 parts of ε-caprolactam, 1-2 parts of emulsifier, and 0.1-1 part of initiator.

2. The polyurethane-modified silicone fluorine-free waterproof agent according to claim 1, characterized in that, The hydroxyl content of α,ω-dihydroxypolydimethylsiloxane is 4-5%.

3. The polyurethane-modified silicone fluorine-free water repellent according to claim 1, characterized in that, The emulsifier includes: sodium dodecyl sulfate and polyoxyethylene lauryl phenol ether.

4. The polyurethane-modified silicone fluorine-free water repellent according to claim 1, characterized in that, The mass ratio of sodium dodecyl sulfate to polyoxyethylene lauryl phenol ether is 1:2-4.

5. The polyurethane-modified silicone fluorine-free waterproof agent according to claim 1, wherein, The initiator is persulfate, specifically ammonium persulfate.

6. A preparation method of the polyurethane-modified silicone fluorine-free waterproof agent according to any one of claims 1-5, characterized in that, It includes the following steps: S1. Mix octamethylcyclotetrasiloxane, γ-aminopropylmethyldiethoxysilane, and toluene evenly, heat up to 80-90 °C under nitrogen protection, dropwise add tetramethylammonium hydroxide under stirring, keep warm for 4-6 h, and remove toluene by vacuum distillation to obtain an organosilicon prepolymer; S2. Mix α,ω-dihydroxypolydimethylsiloxane, glycidyl ether oxypropyltrimethoxysilane, triethylamine, and isopropanol, react at 40-50 °C for 3-5 h, remove isopropanol and methanol to obtain an organosilicon intermediate; S3. Add tetraethyl orthosilicate to absolute ethanol and mix evenly, dropwise add ammonia water to it under stirring, react at 50-60 °C for 1-2 h, add silane coupling agent KH-570, stir at 70-80 °C for 1-2 h, centrifuge, wash, and vacuum dry to obtain silica powder; S4. Mix the organosilicon prepolymer, organosilicon intermediate, hexamethylene diisocyanate, dibutyltin dilaurate, and acetone, pre-react at 60-70 °C for 2-3 h; heat up to 75-80 °C and continue to react, add ε-caprolactam, react at 100-110 °C for 1-2 h, and remove low boilers by vacuum distillation to obtain a block copolymer; S5. Add the block copolymer, silica powder, butyl acrylate, methyl methacrylate, and emulsifier to water and stir evenly, heat up to 60-70 °C, dropwise add the initiator to it under stirring, react for 4-6 h, cool to 30-40 °C, and adjust the pH value of the system to 6.5-7.

7. The preparation method of the polyurethane-modified silicone fluorine-free water repellent according to claim 6, characterized in that, The particle size of the silica powder obtained in S3 is 100-300 nm.

8. The preparation method of the polyurethane-modified silicone fluorine-free water repellent according to claim 6, wherein, In S4, when the conversion rate of the NCO group reaches 50-60% during the pre-reaction, heat up to 75-80 °C.

9. The preparation method of the polyurethane-modified silicone fluorine-free waterproof agent according to claim 6, characterized in that, In S5, adjust the pH value of the system to 6.5-7 with ammonia water.

10. The preparation method of the polyurethane-modified silicone fluorine-free waterproofing agent according to claim 6, characterized in that, The particle size of the polyurethane-modified organosilicon fluorine-free waterproofing agent obtained in S5 is 80-120 nm, and the solid content is 30-35%.

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