A fabric waterproof and breathable coating and a method for preparing the same

Abstract

The present application relates to the technical field of fabric coating, and discloses a waterproof and breathable fabric coating and a preparation method thereof.The waterproof and breathable fabric coating comprises the following raw materials in parts by weight: polyether polyurethane resin 40-50 parts, modified thermal expansion microspheres 5-10 parts, hollow glass microbeads 4-6 parts, modified waterproof agent 8-12 parts, sodium dodecyl sulfate 0.5-1 part, lignocellulose 5-7 parts, silane coupling agent KH-560 3-4 parts, filler 1-3 parts, anti-aging agent 2-4 parts, and ethanol 25-30 parts.The modified waterproof agent can effectively block the penetration of water, avoiding problems such as fabric wetting, water seepage and mildewing when the fabric is exposed to water.The modified thermal expansion microspheres can improve the air permeability of the coating, solving the defects of traditional waterproof coatings, such as poor air permeability and poor wearing comfort.

Description

Technical Field

[0001] This invention relates to the field of fabric coating technology, specifically to a waterproof and breathable fabric coating and its preparation method. Background Technology

[0002] Fabrics, as the core substrate for clothing, home textiles, outdoor protective equipment, and industrial textiles, are widely used in everyday wear, outdoor sports, and industrial protection. Their comfort and functional characteristics directly determine the user experience and applicability of the products. To endow fabrics with both waterproof and breathable functions, functional coating modification is the most widely used technical approach in industrial applications. Currently, commercially available waterproof and breathable coatings mainly use polyurethane, polyacrylate, silicone resin, and fluoropolymers as core raw materials. Among them, polyurethane coatings have become the mainstream application material due to their excellent film-forming flexibility, strong adhesion to fabrics, and strong process adaptability. However, both waterproof and breathable properties of fabrics are important functional indicators that determine their application effectiveness. To endow fabrics with excellent waterproof properties, a hydrophobic protective layer is usually formed on its surface to effectively block water penetration and adapt to the requirements of humid environments and protective scenarios. To ensure good breathability, the coating needs to have a reasonable pore structure to facilitate efficient air conduction. How to improve the waterproof performance of fabrics while optimizing their breathability is the core challenge of current research in this field.

[0003] Patent application number 202111636137.2 discloses a dustproof, hydrophobic, and color-retaining microporous coating for fabrics and its preparation method. It improves the hydrophobic properties of the fabric coating by adding an organosilicon hydrophobic agent and organosilicon resin emulsion, allowing the coating to form a strong hydrophobic film on the fabric surface. However, its weather resistance is weak, its compatibility with inorganic fillers is poor, and the fabric coating does not improve breathability. Patent application number 201711209394.1 discloses a method for preparing a breathable, windproof, and moisture-permeable coating. It effectively improves the windproof breathability, leakage resistance, and reduces blistering and cracking of the coating by adding thermally expanded microcapsules and expanded vermiculite. However, the unmodified microcapsule surface lacks chemical affinity with the polyurethane matrix, which may lead to uneven dispersion, agglomeration, or weak interfacial bonding, affecting the density and long-term stability of the coating. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a waterproof and breathable coating for fabrics and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions: A waterproof and breathable coating for fabrics comprises the following raw materials in parts by weight: 40-50 parts of polyether polyurethane resin, 5-10 parts of modified thermally expandable microspheres, 4-6 parts of hollow glass microspheres, 8-12 parts of modified waterproofing agent, 0.5-1 part of sodium dodecyl sulfate, 5-7 parts of lignocellulose, 3-4 parts of silane coupling agent KH-560, 1-3 parts of filler, 2-4 parts of antioxidant, and 25-30 parts of ethanol; The filler is one or more of talc powder, mica powder, sepiolite, and light calcium carbonate; The antioxidant is one or more of antioxidant 1076, antioxidant 1010, UV-P, and UV-326; The modified waterproofing agent is prepared by the following steps: Step A1: Mix divinylbenzene and hydrogen-containing silicone oil, stir and heat to 120°C, add platinum catalyst, keep the reaction at this temperature for 1 hour to obtain intermediate product 1; Furthermore, the ratio of divinylbenzene, hydrogen-containing silicone oil, and platinum catalyst is 0.2-0.4 mol: 0.1-0.2 mol: 20-40 mg; In step A1, divinylbenzene and hydrogen-containing silicone oil undergo a hydrosilylation reaction, introducing double bonds into the system and providing reaction conditions for subsequent polymerization. Polysiloxane has low surface energy, and due to the encapsulation of side alkyl groups, the entire molecular chain exhibits nonpolarity and hydrophobicity. In addition, the benzene ring also has certain hydrophobic properties.

[0006] Step A2: Mix nano-titanium dioxide and toluene, ultrasonically disperse for 30 min, add vinyltriethoxysilane and triethylamine, stir and react at 50 °C for 24 h under nitrogen protection, cool to room temperature, wash and vacuum dry to obtain intermediate product 2; Furthermore, the ratio of nano-titanium dioxide, toluene, vinyltriethoxysilane, and triethylamine is 1g: 60-70mL: 1-3mmol: 0.1-0.2mL; In step A2, nano-titanium dioxide and vinyltriethoxysilane undergo a grafting reaction to introduce double bonds into the system, providing reaction conditions for the subsequent polymerization reaction. Nano-titanium dioxide is a nano-sized particle that forms nano-sized protrusions on the surface of the fabric fibers, creating a rough structure, reducing the contact area between the fabric and water, and achieving a waterproof effect.

[0007] Step A3: Add intermediate product 2 to cyclohexane, stir for 30 min, then ultrasonically disperse for 30 min, add intermediate product 1 and 1H,1H,2H,2H-perfluorooctyl acrylate, place in an oil bath and heat to 80℃, stir at a constant temperature, when the system temperature reaches 80℃, add 2 / 3 part of benzoyl peroxide, add 1 / 3 part of benzoyl peroxide after 2 h, react for 7 h, pour the product into anhydrous ethanol, stir, wash, and vacuum dry to obtain the modified waterproofing agent; Furthermore, the ratio of intermediate 2, cyclohexane, intermediate 1, 1H,1H,2H,2H-perfluorooctyl acrylate, benzoyl peroxide, and anhydrous ethanol is 0.8 g : 50-60 mL : 0.05-0.1 mol : 0.02-0.04 mol : 0.8-0.9 g : 80-100 mL; In step A3, intermediate product 1 and 1H,1H,2H,2H-perfluorooctyl acrylate undergo in-situ polymerization on the surface of nano-titanium dioxide, which hydrophobically modifies the nano-titanium dioxide, facilitating its uniform dispersion and preventing particle agglomeration. The perfluoroacrylate and polysiloxane impart extremely low surface energy to the coating, constructing a highly efficient hydrophobic interface. The nano-titanium dioxide can improve the coating's density and weather resistance. The synergistic effect of these three components gives the coating both excellent waterproofing and durability.

[0008] The modified thermally expandable microspheres are prepared by the following steps: Step B1: Stir and heat polyethylene glycol-200 to 80°C, add boron trifluoride ether solution, and then dropwise add 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560). After the addition is complete, reflux and stir the reaction for 3 hours. After the reaction is complete, distill under reduced pressure to obtain polyether-KH560. Furthermore, the ratio of polyethylene glycol-200, boron trifluoride ether solution, and KH-560 is 0.2-0.4 mol: 0.12-0.24 g: 0.46-0.92 mol; In step B1, polyethylene glycol-200 and KH-560 undergo a ring-opening reaction, introducing siloxanes into the system and providing reaction conditions for subsequent polymerization. The introduced polyether molecular chains are flexible, which helps to form uniform, tiny channels during the coating curing process. These microstructures provide diffusion channels for air, allowing air to circulate freely and improving air permeability.

[0009] Step B2: Mix carboxyl-containing thermally expandable microspheres (TEMs) with ethanol and stir for 30 min under a nitrogen atmosphere. Add N,N-diisopropylethylamine and O-benzotriazole-tetramethylurea hexafluorophosphate (HBTU) and activate for 5 min. Then add 3-aminopropyltriethoxysilane (KH-550) and react at 40 °C for 3 h. After the reaction is complete, filter, wash and vacuum dry to obtain TEMs-KH550. Furthermore, the ratio of TEMs, ethanol, N,N-diisopropylethylamine, HBTU and KH-550 is 2g:100-150mL:0.012-0.013g:0.008-0.012g:0.02-0.04mol; Furthermore, the TEMs consist of an outer shell and an inner low-boiling-point alkane, wherein the outer shell is one or more of polyacrylonitrile, polymethyl acrylate, acrylonitrile and acrylate copolymers, and the inner low-boiling-point alkane is one or more of n-pentane, isopentane, n-butane and propane. In step B2, TEMs and KH-550 undergo an amide reaction, introducing siloxane groups into the system and providing reaction conditions for subsequent polymerization. When the thermally expanded microspheres are heated, the low-boiling-point solvent inside vaporizes, causing the microspheres to expand and form numerous independent, tiny, sealed balloons. These expanded microspheres and the surrounding coating resin create countless tiny interfacial voids, facilitating airflow and thus imparting excellent breathability to the fabric coating. Step B3: Mix TEMs-KH550 and 50wt% ethanol aqueous solution, stir, adjust the pH of the reaction system to 10 using sodium hydroxide, then add polyether-KH560, react at room temperature for 2 hours, filter, wash, and vacuum dry to obtain modified thermal expansion microspheres. Furthermore, the ratio of TEMs-KH550, ethanol aqueous solution, and polyether-KH560 used is 0.5g:100-120mL:0.05-0.07mol; In step B3, TEMs-KH550 and polyether-KH560 undergo a surface grafting polymerization reaction to form a cross-linked polysiloxane network on the surface of the microspheres. This network effectively blocks water penetration while exhibiting excellent air permeability. Grafting polysiloxane and polyether onto the surface of the thermally expanding microspheres can synergistically improve the air permeability of the polyurethane coating, enhance interfacial compatibility, and achieve long-lasting air permeability.

[0010] A method for preparing a waterproof and breathable coating for fabrics includes the following steps: Step S1: Weigh the raw materials according to the weight parts, mix the modified waterproofing agent and ethanol in a high shear mixer for 0.5-1h, treat under vacuum at 60-80℃ for 0.5-1h, cool to room temperature to obtain a homogeneous mixture, add the modified thermal expansion microspheres, stir for 10-30min, filter to obtain component A; Step S2: Add lignocellulose to the reactor, then add filler and stir to mix evenly. Disperse ultrasonically for 15-20 minutes, then ball mill for 4-6 hours. Add polyether polyurethane resin, sodium dodecyl sulfate and silane coupling agent KH-560, and stir evenly to obtain component B. Mix components A and B and disperse ultrasonically for 25-35 minutes and ball mill for 4-6 hours. Finally, add antioxidant and hollow glass microspheres in sequence, and stir at 200-300 r / min for 10-15 minutes to obtain a waterproof and breathable coating for fabrics.

[0011] The beneficial effects of this invention are: The waterproof and breathable coating for fabrics of this invention can be widely used in textile production fields such as outdoor clothing, sports fabrics, home textiles, and protective workwear. Using the coating of this invention in fabric coating processing can significantly improve the synergistic performance of waterproofing and breathability. By constructing a dense hydrophobic protective layer through modified waterproofing agents, it effectively blocks water penetration, preventing problems such as fabric getting wet, seeping, and mold. Simultaneously, the modified thermally expanding microspheres facilitate air circulation, overcoming the shortcomings of traditional waterproof coatings that are not breathable and have poor wearing comfort. Compared with existing technologies, the coating prepared by this invention has outstanding comprehensive performance, combining protection and comfort, and has broad market application prospects.

[0012] The modified waterproofing agent of this invention first utilizes a hydrosilylation reaction between divinylbenzene and hydrogen-containing silicone oil. The polysiloxane has low surface energy, and due to the encapsulation of side alkyl groups, the entire molecular chain exhibits nonpolarity and hydrophobicity. Furthermore, the benzene ring also possesses certain hydrophobic properties. Next, a grafting reaction is performed between nano-titanium dioxide and vinyltriethoxysilane. The nano-titanium dioxide, being nano-sized particles, forms nano-scale protrusions on the surface of fabric fibers, constructing a rough structure and reducing the contact area between the fabric and water, thus achieving waterproofing. Finally, an in-situ polymerization reaction is used to hydrophobically modify the nano-titanium dioxide, which facilitates uniform dispersion and prevents particle agglomeration. Perfluoroacrylate and polysiloxane impart extremely low surface energy to the coating, constructing a highly efficient hydrophobic interface. The nano-titanium dioxide enhances the coating's density and weather resistance. The synergistic effect of these three components gives the coating both excellent waterproofing and durability.

[0013] The modified thermally expandable microspheres of this invention first undergo a ring-opening reaction with polyethylene glycol-200 and KH-560, introducing flexible polyether molecular chains that facilitate the formation of uniform, microscopic channels during coating curing. These microstructures provide diffusion channels for air, allowing free airflow and improving breathability. Subsequently, an amide reaction is performed with TEMs and KH-550. When heated, the low-boiling-point solvent inside the thermally expandable microspheres vaporizes, causing the microspheres to expand and form numerous independent, microscopic, sealed balloons. Numerous tiny interfacial voids are formed between the expanded microspheres and the surrounding coating resin, further promoting airflow and thus imparting excellent breathability to the fabric coating. Finally, a surface grafting polymerization reaction is used to form a cross-linked polysiloxane network on the microsphere surface, effectively blocking water penetration while maintaining excellent breathability. Grafting polysiloxane and polyether onto the surface of the thermally expandable microspheres synergistically enhances the breathability of the polyurethane coating, improves interfacial compatibility, and achieves long-lasting breathability. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] The following are the sources of some of the raw materials used in the examples: The hydrogen-containing silicone oil was purchased from Shanghai Silicon Power Advanced Materials Co., Ltd., and is a double-ended hydrogen-containing silicone oil. Thermally expandable microspheres were purchased from Forsmann Technology (Beijing) Co., Ltd. Example 1: The modified waterproofing agent was prepared by the following steps: Step A1: Mix divinylbenzene and hydrogen-containing silicone oil, stir and heat to 120°C, add platinum catalyst, keep the reaction at this temperature for 1 hour to obtain intermediate product 1. The ratio of divinylbenzene, hydrogen-containing silicone oil and platinum catalyst is 0.2 mol: 0.1 mol: 20 mg. Step A2: Mix nano-titanium dioxide and toluene, sonicate for 30 min, add vinyltriethoxysilane and triethylamine, stir and react at 50 °C for 24 h under nitrogen protection, cool to room temperature, wash and vacuum dry to obtain intermediate product 2. The ratio of nano-titanium dioxide, toluene, vinyltriethoxysilane and triethylamine is 1 g: 60 mL: 1 mmol: 0.1 mL. Step A3: Add intermediate product 2 to cyclohexane, stir for 30 min, then ultrasonically disperse for 30 min. Add intermediate product 1 and 1H,1H,2H,2H-perfluorooctyl acrylate, place in an oil bath and heat to 80℃, stir at a constant temperature. When the system temperature reaches 80℃, add 2 / 3 part of benzoyl peroxide, and after 2 h, add another 1 / 3 part of benzoyl peroxide. React for 7 h, pour the product into anhydrous ethanol, stir, wash, and vacuum dry to obtain the modified waterproofing agent. The ratio of intermediate product 2, cyclohexane, intermediate product 1, 1H,1H,2H,2H-perfluorooctyl acrylate, benzoyl peroxide, and anhydrous ethanol is 0.8 g: 50 mL: 0.05 mol: 0.02 mol: 0.8 g: 80 mL.

[0016] The modified thermally expandable microspheres were prepared by the following steps: Step B1: Polyethylene glycol-200 was stirred and heated to 80°C, boron trifluoride ether solution was added, and then KH-560 was added dropwise. After the addition was complete, the mixture was refluxed and stirred for 3 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain polyether-KH560. The ratio of the amount of polyethylene glycol-200, boron trifluoride ether solution and KH-560 was 0.2 mol: 0.12 g: 0.46 mol. Step B2: Mix TEMs and ethanol, stir for 30 min under a nitrogen atmosphere, add N,N-diisopropylethylamine and HBTU, activate for 5 min, then add KH-550, react at 40℃ for 3 h, filter, wash, and vacuum dry to obtain TEMs-KH550. The ratio of TEMs, ethanol, N,N-diisopropylethylamine, HBTU and KH-550 is 2 g: 100 mL: 0.012 g: 0.008 g: 0.02 mol. Step B3: Mix TEMs-KH550 and 50wt% ethanol aqueous solution, stir, adjust the pH of the reaction system to 10 using sodium hydroxide, then add polyether-KH560, react at room temperature for 2 hours, filter, wash, and vacuum dry to obtain modified thermal expansion microspheres. The ratio of TEMs-KH550, ethanol aqueous solution and polyether-KH560 is 0.5g:100mL:0.05mol.

[0017] Example 2: The modified waterproofing agent was prepared by the following steps: Step A1: Mix divinylbenzene and hydrogen-containing silicone oil, stir and heat to 120°C, add platinum catalyst, keep the reaction at this temperature for 1 hour to obtain intermediate product 1. The ratio of divinylbenzene, hydrogen-containing silicone oil and platinum catalyst is 0.3 mol: 0.15 mol: 30 mg. Step A2: Mix nano-titanium dioxide and toluene, sonicate for 30 min, add vinyltriethoxysilane and triethylamine, stir and react at 50 °C for 24 h under nitrogen protection, cool to room temperature, wash and vacuum dry to obtain intermediate product 2. The ratio of nano-titanium dioxide, toluene, vinyltriethoxysilane and triethylamine is 1 g: 65 mL: 2 mmol: 0.15 mL. Step A3: Add intermediate product 2 to cyclohexane, stir for 30 min, then ultrasonically disperse for 30 min. Add intermediate product 1 and 1H,1H,2H,2H-perfluorooctyl acrylate, place in an oil bath and heat to 80℃, stir at a constant temperature. When the system temperature reaches 80℃, add 2 / 3 part of benzoyl peroxide, and after 2 h, add another 1 / 3 part of benzoyl peroxide. React for 7 h, pour the product into anhydrous ethanol, stir, wash, and vacuum dry to obtain the modified waterproofing agent. The ratio of intermediate product 2, cyclohexane, intermediate product 1, 1H,1H,2H,2H-perfluorooctyl acrylate, benzoyl peroxide, and anhydrous ethanol is 0.8 g: 55 mL: 0.075 mol: 0.03 mol: 0.85 g: 90 mL.

[0018] The modified thermally expandable microspheres were prepared by the following steps: Step B1: Polyethylene glycol-200 was stirred and heated to 80°C, boron trifluoride ether solution was added, and then KH-560 was added dropwise. After the addition was complete, the mixture was refluxed and stirred for 3 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain polyether-KH560. The ratio of the amount of polyethylene glycol-200, boron trifluoride ether solution and KH-560 was 0.3 mol: 0.18 g: 0.69 mol. Step B2: Mix TEMs and ethanol, stir for 30 min under a nitrogen atmosphere, add N,N-diisopropylethylamine and HBTU, activate for 5 min, then add KH-550, react at 40℃ for 3 h, filter, wash, and vacuum dry to obtain TEMs-KH550. The ratio of TEMs, ethanol, N,N-diisopropylethylamine, HBTU and KH-550 is 2 g: 125 mL: 0.0125 g: 0.01 g: 0.03 mol. Step B3: Mix TEMs-KH550 and 50wt% ethanol aqueous solution, stir, adjust the pH of the reaction system to 10 using sodium hydroxide, then add polyether-KH560, react at room temperature for 2 hours, filter, wash, and vacuum dry to obtain modified thermal expansion microspheres. The ratio of TEMs-KH550, ethanol aqueous solution and polyether-KH560 is 0.5g:110mL:0.06mol.

[0019] Example 3: The modified waterproofing agent was prepared by the following steps: Step A1: Mix divinylbenzene and hydrogen-containing silicone oil, stir and heat to 120°C, add platinum catalyst, keep the reaction at this temperature for 1 hour to obtain intermediate product 1. The ratio of divinylbenzene, hydrogen-containing silicone oil and platinum catalyst is 0.4 mol: 0.2 mol: 40 mg. Step A2: Mix nano-titanium dioxide and toluene, sonicate for 30 min, add vinyltriethoxysilane and triethylamine, stir and react at 50 °C for 24 h under nitrogen protection, cool to room temperature, wash and vacuum dry to obtain intermediate product 2. The ratio of nano-titanium dioxide, toluene, vinyltriethoxysilane and triethylamine is 1 g: 70 mL: 3 mmol: 0.2 mL. Step A3: Add intermediate product 2 to cyclohexane, stir for 30 min, then ultrasonically disperse for 30 min. Add intermediate product 1 and 1H,1H,2H,2H-perfluorooctyl acrylate, place in an oil bath and heat to 80℃, stir at a constant temperature. When the system temperature reaches 80℃, add 2 / 3 part of benzoyl peroxide, and after 2 h, add another 1 / 3 part of benzoyl peroxide. React for 7 h, pour the product into anhydrous ethanol, stir, wash, and vacuum dry to obtain the modified waterproofing agent. The ratio of intermediate product 2, cyclohexane, intermediate product 1, 1H,1H,2H,2H-perfluorooctyl acrylate, benzoyl peroxide, and anhydrous ethanol is 0.8 g: 60 mL: 0.1 mol: 0.04 mol: 0.9 g: 100 mL.

[0020] The modified thermally expandable microspheres were prepared by the following steps: Step B1: Polyethylene glycol-200 was stirred and heated to 80°C, boron trifluoride ether solution was added, and then KH-560 was added dropwise. After the addition was complete, the mixture was refluxed and stirred for 3 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain polyether-KH560. The ratio of the amount of polyethylene glycol-200, boron trifluoride ether solution and KH-560 was 0.4 mol: 0.24 g: 0.92 mol. Step B2: Mix TEMs and ethanol, stir for 30 min under a nitrogen atmosphere, add N,N-diisopropylethylamine and HBTU, activate for 5 min, then add KH-550, react at 40℃ for 3 h, filter, wash, and vacuum dry to obtain TEMs-KH550. The ratio of TEMs, ethanol, N,N-diisopropylethylamine, HBTU and KH-550 is 2 g: 150 mL: 0.013 g: 0.012 g: 0.04 mol. Step B3: Mix TEMs-KH550 and 50wt% ethanol aqueous solution, stir, adjust the pH of the reaction system to 10 using sodium hydroxide, then add polyether-KH560, react at room temperature for 2 hours, filter, wash, and vacuum dry to obtain modified thermal expansion microspheres. The ratio of TEMs-KH550, ethanol aqueous solution and polyether-KH560 is 0.5g:120mL:0.07mol.

[0021] Example 4: A method for preparing a waterproof and breathable coating for fabrics includes the following steps: 40 parts of polyether-type polyurethane resin, 5 parts of modified thermal expansion microspheres prepared in Example 1, 4 parts of hollow glass microspheres, 8 parts of modified waterproofing agent prepared in Example 1, 0.5 parts of sodium dodecyl sulfate, 5 parts of lignocellulose, 3 parts of silane coupling agent KH-560, 1 part of talc, 1 part of antioxidant 1076, 1 part of UV-P, and 25 parts of ethanol. Step S1: Weigh the raw materials according to the weight parts, mix the modified waterproofing agent prepared in Example 1 and ethanol in a high shear mixer for 0.5 h, treat under vacuum at 60°C for 0.5 h, cool to room temperature to obtain a homogeneous mixture, add the modified thermal expansion microspheres prepared in Example 1, stir for 10 min, filter to obtain component A; Step S2: Add lignocellulose to the reactor, then add talc powder and stir to mix evenly. Disperse by ultrasonication for 15 minutes, then disperse by ball milling for 4 hours. Then add polyether polyurethane resin, sodium dodecyl sulfate and silane coupling agent KH-560, and stir evenly to obtain component B. Mix components A and B and disperse by ultrasonication for 25 minutes and ball milling for 4 hours. Finally, add antioxidant 1076, UV-P and hollow glass microspheres in sequence, and stir at 200 r / min for 10 minutes to obtain a waterproof and breathable coating for fabrics.

[0022] Example 5: A method for preparing a waterproof and breathable coating for fabrics includes the following steps: 45 parts of polyether-type polyurethane resin, 8 parts of modified thermal expansion microspheres prepared in Example 2, 5 parts of hollow glass microspheres, 10 parts of modified waterproofing agent prepared in Example 2, 0.5 parts of sodium dodecyl sulfate, 5 parts of lignocellulose, 3.5 parts of silane coupling agent KH-560, 1 part of mica powder, 1 part of light calcium carbonate, 1 part of antioxidant 1010, 2 parts of UV-326, and 30 parts of ethanol. Step S1: Weigh the raw materials according to the weight parts, mix the modified waterproofing agent prepared in Example 2 and ethanol in a high shear mixer for 1 hour, treat under vacuum at 70°C for 1 hour, cool to room temperature to obtain a homogeneous mixture, add the modified thermal expansion microspheres prepared in Example 2, stir for 20 minutes, filter, and obtain component A; Step S2: Add lignocellulose to the reactor, then add mica powder and light calcium carbonate and stir to mix evenly. Disperse by ultrasonication for 20 minutes, then disperse by ball milling for 5 hours. Then add polyether polyurethane resin, sodium dodecyl sulfate and silane coupling agent KH-560 and stir evenly to obtain component B. Mix components A and B and disperse by ultrasonication for 30 minutes and ball milling for 5 hours. Finally, add antioxidant 1010, UV-326 and hollow glass microspheres in sequence and stir at 300 r / min for 15 minutes to obtain a waterproof and breathable coating for fabrics.

[0023] Example 6: A method for preparing a waterproof and breathable coating for fabrics includes the following steps: 50 parts of polyether-type polyurethane resin, 10 parts of modified thermally expandable microspheres prepared in Example 3, 6 parts of hollow glass microspheres, 12 parts of modified waterproofing agent prepared in Example 3, 1 part of sodium dodecyl sulfate, 7 parts of lignocellulose, 4 parts of silane coupling agent KH-560, 1 part of sepiolite, 2 parts of light calcium carbonate, 1 part of antioxidant 1076, 3 parts of UV-326, and 30 parts of ethanol. Step S1: Weigh the raw materials according to the weight parts, mix the modified waterproofing agent prepared in Example 3 and ethanol in a high shear mixer for 1 hour, treat under vacuum at 80°C for 1 hour, cool to room temperature to obtain a homogeneous mixture, add the modified thermal expansion microspheres prepared in Example 3, stir for 30 minutes, filter, and obtain component A; Step S2: Add lignocellulose to the reactor, then add sepiolite and light calcium carbonate and stir to mix evenly. Disperse by ultrasonication for 20 minutes, then disperse by ball milling for 6 hours. Then add polyether polyurethane resin, sodium dodecyl sulfate and silane coupling agent KH-560 and stir evenly to obtain component B. Mix components A and B and disperse by ultrasonication for 35 minutes and ball milling for 6 hours. Finally, add antioxidant 1076, UV-326 and hollow glass microspheres in sequence and stir at 300 r / min for 15 minutes to obtain a waterproof and breathable coating for fabrics.

[0024] Comparative Example 1: This comparative example is a coating, which differs from Example 6 in that polydimethylsiloxane is used instead of the modified waterproofing agent prepared in Example 3, and all other aspects are the same.

[0025] Comparative Example 2: This comparative example is a coating, which differs from Example 6 in that the modified thermal expansion microspheres prepared in Example 3 are not added, but otherwise they are the same.

[0026] Comparative Example 3: This comparative example is a coating, which differs from Example 6 in that polydimethylsiloxane is used instead of the modified waterproofing agent prepared in Example 3, and the modified thermal expansion microspheres prepared in Example 3 are not added. All other aspects are the same.

[0027] Using a blade coating process, the coatings from Examples 4-6 and Comparative Examples 1-3 were applied to both sides of polyester fabric using a blade. The performance of the treated fabrics was then tested. Water contact angle: Measured using an SDC-100 contact angle meter; Waterproof performance: Take a fabric with a width of 150mm and a length of 200mm, and determine the time when abnormal phenomena such as water permeability, wetness, and damage occur in the fabric according to HG / T 2582-2022; Air permeability: The air permeability of the fabric was determined in accordance with GB / T 5453-2025.

[0028] The test results are shown in Table 1: Table 1: Performance Test Results

[0029] As shown in Table 1, the waterproof and breathable fabric coating prepared by this invention is waterproof. Using the coating prepared in the examples, the water contact angle of polyester fabric can reach over 141.8°. As shown in Example 6 and Comparative Example 1, the modified waterproofing agent prepared by this invention increases the water contact angle of the fabric, effectively blocking water penetration. As shown in Example 6 and Comparative Example 2, the modified thermally expanding microspheres prepared by this invention improve the breathability of the coating. This demonstrates that the waterproof and breathable fabric coating of this invention improves waterproofness without compromising comfort, exhibiting outstanding overall performance.

[0030] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A waterproof and breathable coating for fabrics, characterized in that, The raw materials include the following parts by weight: 40-50 parts of polyether polyurethane resin, 5-10 parts of modified thermal expansion microspheres, 4-6 parts of hollow glass microspheres, 8-12 parts of modified waterproofing agent, 0.5-1 part of sodium dodecyl sulfate, 5-7 parts of lignocellulose, 3-4 parts of silane coupling agent KH-560, 1-3 parts of filler, 2-4 parts of antioxidant, and 25-30 parts of ethanol. The modified waterproofing agent is prepared by the following steps: Step A1: Mix divinylbenzene and hydrogen-containing silicone oil, stir and heat to 120°C, add platinum catalyst, keep the reaction at this temperature for 1 hour to obtain intermediate product 1; Step A2: Mix nano-titanium dioxide and toluene, ultrasonically disperse for 30 min, add vinyltriethoxysilane and triethylamine, stir and react at 50 °C for 24 h under nitrogen protection, cool to room temperature, wash and vacuum dry to obtain intermediate product 2; Step A3: Add intermediate product 2 to cyclohexane, stir for 30 min, then ultrasonically disperse for 30 min, add intermediate product 1 and 1H,1H,2H,2H-perfluorooctyl acrylate, place in an oil bath and heat to 80℃, stir at a constant temperature, when the system temperature reaches 80℃, add 2 / 3 part of benzoyl peroxide, add 1 / 3 part of benzoyl peroxide after 2 h, react for 7 h, pour the product into anhydrous ethanol, stir, wash, and vacuum dry to obtain the modified waterproofing agent.

2. The waterproof and breathable coating for fabrics according to claim 1, characterized in that, In step A1, the ratio of divinylbenzene, hydrogen-containing silicone oil, and platinum catalyst is 0.2-0.4 mol: 0.1-0.2 mol: 20-40 mg.

3. The waterproof and breathable coating for fabrics according to claim 1, characterized in that, In step A2, the ratio of nano-titanium dioxide, toluene, vinyltriethoxysilane, and triethylamine is 1g: 60-70mL: 1-3mmol: 0.1-0.2mL.

4. The waterproof and breathable coating for fabrics according to claim 1, characterized in that, In step A3, the ratio of intermediate product 2, cyclohexane, intermediate product 1, 1H,1H,2H,2H-perfluorooctyl acrylate, benzoyl peroxide, and anhydrous ethanol is 0.8g: 50-60mL: 0.05-0.1mol: 0.02-0.04mol: 0.8-0.9g: 80-100mL.

5. The waterproof and breathable coating for fabrics according to claim 1, characterized in that, The modified thermally expandable microspheres are prepared by the following steps: Step B1: Stir and heat polyethylene glycol-200 to 80°C, add boron trifluoride diethyl ether solution, and then add KH-560 dropwise. After the addition is complete, reflux and stir the reaction for 3 hours. After the reaction is completed, distill under reduced pressure to obtain polyether-KH560. Step B2: Mix TEMs and ethanol, stir for 30 min under a nitrogen atmosphere, add N,N-diisopropylethylamine and HBTU, activate for 5 min, then add KH-550, react at 40 °C for 3 h, filter, wash and vacuum dry after the reaction to obtain TEMs-KH550. Step B3: Mix TEMs-KH550 and 50wt% ethanol aqueous solution, stir, adjust the pH of the reaction system to 10 using sodium hydroxide, then add polyether-KH560, react at room temperature for 2 hours, filter, wash, and vacuum dry to obtain modified thermal expansion microspheres.

6. The waterproof and breathable coating for fabrics according to claim 5, characterized in that, In step B1, the ratio of polyethylene glycol-200, boron trifluoride ether solution, and KH-560 is 0.2-0.4 mol: 0.12-0.24 g: 0.46-0.92 mol.

7. The waterproof and breathable coating for fabrics according to claim 5, characterized in that, In step B2, the ratio of TEMs, ethanol, N,N-diisopropylethylamine, HBTU, and KH-550 is 2g:100-150mL:0.012-0.013g:0.008-0.012g:0.02-0.04mol. The TEMs consist of an outer shell and an inner low-boiling-point alkane. The outer shell is one or more of polyacrylonitrile, polymethyl acrylate, acrylonitrile, and acrylate copolymers, and the inner low-boiling-point alkane is one or more of n-pentane, isopentane, n-butane, and propane.

8. The waterproof and breathable coating for fabrics according to claim 5, characterized in that, In step B3, the ratio of TEMs-KH550, ethanol aqueous solution, and polyether-KH560 is 0.5g: 100-120mL: 0.05-0.07mol.

9. The waterproof and breathable coating for fabrics according to claim 1, characterized in that, The filler is one or more of talc powder, mica powder, sepiolite and light calcium carbonate, and the antioxidant is one or more of antioxidant 1076, antioxidant 1010, UV-P and UV-326.

10. A method for preparing the waterproof and breathable coating for fabrics according to any one of claims 1-9, characterized in that, The waterproof and breathable coating for the fabric is prepared by the following steps: Step S1: Weigh the raw materials according to the weight parts, mix the modified waterproofing agent and ethanol in a high shear mixer for 0.5-1h, treat under vacuum at 60-80℃ for 0.5-1h, cool to room temperature to obtain a homogeneous mixture, add the modified thermal expansion microspheres, stir for 10-30min, filter to obtain component A; Step S2: Add lignocellulose to the reactor, then add filler and stir to mix evenly. Disperse ultrasonically for 15-20 minutes, then ball mill for 4-6 hours. Add polyether polyurethane resin, sodium dodecyl sulfate and silane coupling agent KH-560, and stir evenly to obtain component B. Mix components A and B and disperse ultrasonically for 25-35 minutes and ball mill for 4-6 hours. Finally, add antioxidant and hollow glass microspheres in sequence, and stir at 200-300 r / min for 10-15 minutes to obtain a waterproof and breathable coating for fabrics.

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