Modified nano-silica-reactive polyurethane cross-linking waterproofing agent and preparation method

Abstract

The present invention discloses a modified nano-silica-reactive polyurethane cross-linked waterproofing agent, a modified nano-silica for preparing the waterproofing agent, a reactive polyurethane, a modified nano-silica-reactive polyurethane cross-linked product, and a preparation method of the waterproofing agent. The modified nano-silica-reactive polyurethane cross-linked waterproofing agent is prepared by modifying nano-silica with a long-chain alkylsilane coupling agent and an azidosilane coupling agent, and the modified nano-silica is reacted with a synthesized reactive polyurethane through a 1,3-dip cycloaddition reaction to obtain a modified nano-silica-reactive polyurethane cross-linked hydrophobic compound, which is then removed from the solvent and emulsified. The waterproofing agent preparation method of the present invention is efficient and simple, has a high conversion rate, and has few by-products. The product is used for waterproof finishing of cotton and chemical fiber fabrics, can give fibers excellent waterproof properties, and has a good wash-resistant and long-lasting waterproof effect.

Description

Technical Field

[0001] The present invention belongs to the field of textile auxiliary technology, and specifically relates to a modified nano-silica-reactive polyurethane cross-linked waterproofing agent. The invention is a fluorine-free waterproofing agent used for water-repellent finishing of textile fiber fabrics. The invention also relates to modified nano-silica, reactive polyurethane, and a modified nano-silica-reactive polyurethane cross-linked product used to prepare the waterproofing agent, and further relates to a method for preparing the waterproofing agent. Background Art

[0002] Currently, perfluoroalkyl-based fluorine-based water repellents are commonly used for fiber waterproofing. Fluorine-based water repellents are typically derived from monomers containing long-chain alkyl groups with perfluoro groups through polymerization or copolymerization. Due to the low surface energy of the fluorocarbon segments, fibers treated with fluorine-based additives can achieve excellent water and oil repellency.

[0003] In recent years, due to the global concern about the environmental ecological problems caused by the low biodegradability and cumulative effects of fully fluorinated compounds, it has become an inevitable trend to reduce the use of fluorine-based waterproofing agents and replace them with non-fluorine-based products whose performance can match that of fluorine-based waterproofing agents.

[0004] Currently, many fluorine-free products have emerged as alternatives to fluorine-based compounds, including modified paraffin waxes, polyacrylates, and silicones. Although these technologies can provide water-repellent properties for fabrics, their effectiveness is generally lower than that of their fluorinated counterparts.

[0005] Chinese patent CN111910439 discloses an inorganic nano-silica hybrid organosilicon fluorine-free water repellent and its preparation method. The method involves reacting a cross-linked long-chain alkyl / amino co-modified organosilicon with epoxy-modified nano-silica in isopropyl alcohol to produce an inorganic nano-silica hybrid long-chain alkyl organosilicon. After emulsification, the inorganic nano-silica hybrid organosilicon fluorine-free water repellent is obtained. This product, used for waterproofing cotton fabrics, imparts excellent waterproofing, durability, and a soft feel.

[0006] Polyurethane compounds have unique film-forming properties, water repellency, a soft hand feel, and a high affinity for fibers. They are widely used in various functional finishes on textile fibers and can also be used as carriers to impart various functional characteristics to fibers, such as flame retardancy, UV protection, and water resistance. Polyurethane-nanosilica composites can combine the advantages of both, resulting in synergistic performance. However, nanosilica has high surface energy and highly reactive hydroxyl groups on its surface, making it prone to agglomeration when directly blended with polyurethane. Therefore, silane coupling agents are commonly used to modify nanosilica to enhance its hydrophobicity and improve its dispersibility and compatibility in polymers. Because silane-coupling-agent-modified silica has difficulty bonding with the highly polar urethane groups in polyurethane, the dispersion of silane-coupling-agent-modified nanosilica in a polyurethane matrix remains unsatisfactory, with microphase separation occurring, ultimately impacting the overall performance of the composite material. Summary of the Invention

[0007] The first object of the present invention is to provide a modified nano-silica-reactive polyurethane cross-linking waterproofing agent with good and durable waterproofing performance.

[0008] The first object of the present invention is achieved through the following technical measures: a modified nano-silica-reactive polyurethane cross-linked waterproofing agent, characterized in that it is obtained by removing the solvent and emulsifying the modified nano-silica generated by long-chain alkyl and azid-modified nano-silica, and obtaining a modified nano-silica-reactive polyurethane cross-linked product through an addition reaction with reactive polyurethane.

[0009] The present invention chemically bonds hydrophobically modified nano-silica to a polyurethane matrix, significantly improving the compatibility of the nano-silica with the polyurethane matrix, resulting in a chemically modified hydrophobic nano-silica-reactive polyurethane composite material. Due to the polyurethane matrix's high affinity for fibers, the hydrophobically modified nano-silica can be uniformly adsorbed and arranged on the fibers, imparting excellent waterproof properties to the fibers. Furthermore, because the polyurethane matrix in the present invention is a reactive polyurethane, the polyurethane-silica composite material can be wrapped or chemically bonded to the fiber substrate, resulting in a highly washable adsorption and ultimately providing a long-lasting waterproof effect. Therefore, the present invention can be used for waterproofing cotton and chemical fiber fabrics, achieving excellent and long-lasting waterproof properties.

[0010] The second object of the present invention is to provide a modified nano-silica for preparing the above-mentioned modified nano-silica-reactive polyurethane cross-linking waterproofing agent.

[0011] The second object of the present invention is achieved through the following technical measures: a modified nano-silica for preparing the above-mentioned modified nano-silica-reactive polyurethane cross-linking waterproofing agent, characterized in that it is obtained by modifying nano-silica with a long carbon chain silane coupling agent and a silane azide coupling agent.

[0012] The modified nano-silica of the present invention is composed of 85-96% solvent, 1-6% silicon dioxide, 1-4% silane azide coupling agent and 2-5% long carbon chain silane coupling agent in weight percentage, and the total weight percentage of each raw material is 100%.

[0013] The long carbon chain silane coupling agent of the present invention is one or a combination of two or more of dodecyltrimethoxysilane, hexadecyltrimethoxysilane and octadecyltrimethoxysilane.

[0014] The silane azide coupling agent of the present invention is produced by the reaction of a chlorine-containing silane coupling agent and sodium azide.

[0015] The chlorine-containing silane coupling agent of the present invention is 3-chloropropyltrimethoxysilane or 3-chloropropyltriethoxysilane.

[0016] The third object of the present invention is to provide a reactive polyurethane for preparing the above-mentioned modified nano-silica-reactive polyurethane cross-linking waterproofing agent.

[0017] The third object of the present invention is achieved by the following technical measures: a reactive polyurethane for preparing the above-mentioned modified nano-silica-reactive polyurethane cross-linked waterproofing agent, characterized in that it consists of a polyisocyanate, a polyol monomer, N-propargyl-2,2'-dihydroxydiethylamine, a chain extender and a capping agent, wherein the molar ratio of the polyisocyanate to the polyol monomer is 2.5 to 1.2:1; the N-propargyl-2,2'-dihydroxydiethylamine is prepared by dropwise adding bromopropyne to a tetrahydrofuran solution in which di(2-hydroxyethyl)amine and triethylamine are dissolved, wherein the molar ratio of di(2-hydroxyethyl)amine to triethylamine is 1:1 to 3, and the molar ratio of triethylamine to bromopropyne is 1 to 1.5:1. After the reaction is completed, the mixture is filtered, washed with tetrahydrofuran, and concentrated by reduced pressure distillation.

[0018] The polyisocyanate of the present invention is one or a mixture of two or more substances having two or more isocyanate groups; the polyol monomer is one or a combination of two or more of polyester polyol, polycarbonate diol and polytetramethylene glycol; the chain extender is one or a combination of two or more of 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, dimethylolpropionic acid, dimethylolbutyric acid, diethanolamine, triethanolamine, N-methyldiethanolamine, ethylenediamine, hexamethylenediamine, isophoronediamine, diethylenetriamine and triethylenetetramine; and the end-capping agent is phenol, caprolactam, acetone oxime, methyl ethyl ketone oxime or 3,5-dimethylpyrazole.

[0019] The fourth object of the present invention is to provide a modified nano-silica-reactive polyurethane cross-linked product for preparing the above-mentioned modified nano-silica-reactive polyurethane cross-linked waterproofing agent.

[0020] The fourth object of the present invention is achieved by the following technical measures: a modified nano-silica-reactive polyurethane cross-linked product for preparing the above-mentioned modified nano-silica-reactive polyurethane cross-linked waterproofing agent, characterized in that it is obtained by the addition reaction of modified nano-silica and reactive polyurethane, wherein the modified nano-silica is obtained by modifying nano-silica with a long carbon chain silane coupling agent and an azide silane coupling agent, and the azide silane coupling agent is obtained by reacting a chlorine-containing silane coupling agent and sodium azide in a solvent and under a nitrogen atmosphere, and then extracting with n-hexane multiple times and concentrating by reduced pressure distillation; the reactive polyurethane is composed of polyisocyanate, polyol monomer, N-propargyl-2,2'-dihydroxydiethylamine, a chain extender and a capping agent, and the molar ratio of the isocyanate to the polyol monomer is 2.5 to 1.2:1. The N-propargyl-2,2'-dihydroxydiethylamine is prepared by dropwise adding propargyl bromide to a tetrahydrofuran solution containing di(2-hydroxyethyl)amine and triethylamine, wherein the molar ratio of di(2-hydroxyethyl)amine to triethylamine is 1:1-3, and the molar ratio of triethylamine to propargyl bromide is 1-1.5:1. After the reaction is completed, the mixture is filtered, washed with tetrahydrofuran, and concentrated by distillation under reduced pressure.

[0021] The fifth object of the present invention is to provide a method for preparing the modified nano-silica-reactive polyurethane cross-linking waterproofing agent.

[0022] The fifth object of the present invention is achieved by the following technical measures: a preparation method for preparing the modified nano-silica-reactive polyurethane cross-linked waterproofing agent, characterized by comprising the following steps:

[0023] S1, generating modified nano-silica by long-chain alkyl and azide-modified nano-silica;

[0024] S2. preparing reactive polyurethane;

[0025] S3, subjecting the modified nano-silica prepared in step S1 to an addition reaction with the reactive polyurethane prepared in step S2 to obtain a modified nano-silica-reactive polyurethane cross-linked product;

[0026] S4. The modified nano-silica-reactive polyurethane cross-linked product obtained in step S3 is subjected to solvent removal and emulsification to obtain a modified nano-silica-reactive polyurethane cross-linked waterproofing agent.

[0027] In the step S1 of the present invention, dried nano-silica is ultrasonically dispersed in a solvent, nitrogen is introduced, a silane azide coupling agent is added, ultrasonication is carried out for 10 to 60 minutes, a long carbon chain silane coupling agent is added, stirring and reacting at 100 to 110° C. for 12 to 24 hours, cooling to room temperature, washing and drying to obtain modified nano-silica.

[0028] The silane azide coupling agent of the present invention is prepared by reacting a chlorine-containing silane coupling agent and sodium azide in a solvent under a nitrogen atmosphere, extracting with n-hexane, and concentrating by reduced pressure distillation.

[0029] In the step S2 of the present invention, polyisocyanate and polyol monomer react in a solvent to synthesize a prepolymer, the reaction temperature is 70-100° C., and the reaction time is 3-8 hours. Then, N-propargyl-2,2'-dihydroxydiethylamine, a chain extender, and a capping agent are added to the prepolymer, and the reaction temperature is 40-100° C. and the reaction time is 1-4 hours until no free isocyanate remains, thereby obtaining a reactive polyurethane.

[0030] In the step S3 of the present invention, nano-silica is added to reactive polyurethane under a nitrogen atmosphere, ultrasonically dispersed for 30 minutes, and then copper sulfate pentahydrate and sodium ascorbate are added. The mixture is stirred and reacted for 6 to 12 hours under nitrogen protection to obtain a modified nano-silica-reactive polyurethane cross-linked product, wherein the amount of copper sulfate pentahydrate is 0.05 to 0.1% of the reactive polyurethane, and the molar ratio of copper sulfate pentahydrate to sodium ascorbate is 1:1 to 2.0.

[0031] In step S4 of the present invention, the modified nano-silica-reactive polyurethane crosslinked product is mixed with an emulsifier and deionized water, and then homogenized and emulsified to obtain the product. The emulsifier is selected from one or more combinations of nonionic and cationic surfactants; the emulsifier is selected from nonionic emulsifiers such as linear fatty alcohol polyoxyethylene ethers, isomeric fatty alcohol polyoxyethylene ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid glycerides, and fatty acid polyglycerol esters; or one or more combinations of cationic emulsifiers such as alkylamines, alkyl tertiary amines, alkyl quaternary ammonium salts, alkyl ester quaternary ammonium salts, alkyl acyl quaternary ammonium salts, and polyoxyethylene alkyl quaternary ammonium salts. The amount of the emulsifier is 10-20% of the modified nano-silica-reactive polyurethane crosslinked product.

[0032] Compared with the prior art, the present invention has the following significant effects:

[0033] The preparation method of the waterproofing agent of the present invention is efficient and simple, with a high conversion rate and few by-products. The product is used for waterproofing cotton and chemical fiber fabrics, imparting excellent waterproof properties to the fibers and exhibiting good washability and long-lasting waterproofing effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Figure 1 It is a reaction principle diagram of the present invention. DETAILED DESCRIPTION

[0036] Example 1

[0037] A method for preparing a modified nano-silica-reactive polyurethane cross-linked waterproofing agent comprises the following steps:

[0038] S1, generating modified nano-silica by long-chain alkyl and azide-modified nano-silica;

[0039] S2. preparing reactive polyurethane;

[0040] S3, subjecting the modified nano-silica prepared in step S1 and the reactive polyurethane prepared in step S2 to an addition reaction to obtain a modified nano-silica-reactive polyurethane cross-linked product;

[0041] S4. The modified nano-silica-reactive polyurethane cross-linked product obtained in step S3 is subjected to solvent removal and emulsification to obtain a modified nano-silica-reactive polyurethane cross-linked waterproofing agent.

[0042] Step S1 specifically includes:

[0043] Synthesis of nano-silica modified with long-chain alkylsilane coupling agent and azidosilane coupling agent: 1000 ml of dimethyl sulfoxide (DMSO) was added to a three-necked flask, and nitrogen was introduced. 36.8 g of 3-chloropropyltriethoxysilane and 15.8 g of sodium azide were then added to the flask in sequence. The mixture was stirred at 100°C for 24 hours and then cooled to room temperature. The organic phase was extracted with n-hexane, and then the solvent was removed by distillation under reduced pressure to obtain the azidosilane coupling agent. Take 33.3g of dried nano-silica, ultrasonically disperse it in 1000ml of DMSO, pass nitrogen, add 18.9g of azidosilane coupling agent, add 46.7g of hexadecyltrimethoxysilane, ultrasonicate for 30min, stir and react at 100℃ for 24h. After the reaction is completed, cool to room temperature, centrifuge and wash with acetone in turn, disperse and centrifuge, and vacuum dry to obtain long-chain alkylsilane coupling agent and azidosilane coupling agent modified nano-silica.

[0044] Synthesis of N-propargyl-2,2'-dihydroxydiethylamine: In an ice bath, add 150 ml of tetrahydrofuran, 35 g of di(2-hydroxyethyl)amine, and 53.9 g of triethylamine to a three-necked flask. After dissolution, slowly add 62 g of 1-bromopropyne dropwise. After complete addition, continue the reaction at 0-5°C for 4 hours. After completion of the reaction, filter the product, and remove low-boiling components under reduced pressure on a rotary evaporator to obtain N-propargyl-2,2'-dihydroxydiethylamine.

[0045] Step S2 specifically includes:

[0046] In a three-necked flask, 73.9 g of polycarbonate diol (DUNANOL T5651, produced by Asahi Chemical Co., Ltd., Japan) and 78.8 g of polytetramethylene glycol (molecular weight 2000) were added, diphenylmethane diisocyanate (MDI) was added, the temperature was raised to 70°C, 0.06 g of dibutyltin dilaurate was added, and the reaction was carried out for 2 to 6 hours. The free NCO (isocyanate) content of the system was monitored by di-n-butylamine titration to the theoretical value, 8.4 g of N-propargyl-2,2'-dihydroxydiethylamine, 1.4 g of 1,3-propylene glycol and 2.5 g of butanone oxime were added, a small amount of acetone was added during the reaction to reduce the viscosity, and the reaction was carried out at 70°C for 1 to 4 hours until the free NCO disappeared to obtain a reactive polyurethane.

[0047] Steps S3 and S4 specifically include:

[0048] 46 g of the reactive polyurethane was placed in a three-necked flask at room temperature and purged with nitrogen. 28.8 g of nanosilica modified with a long-chain alkylsilane coupling agent and an azide silane coupling agent was added and ultrasonically dispersed for 30 minutes. 0.04 g of CuSO₄·5H₂O and 0.035 g of sodium ascorbate were added and stirred for 10 hours to obtain a nanosilica-reactive polyurethane crosslinked product. 4.2 g of TWEEN 80, 2.8 g of isomeric tridecanol polyoxyethylene 7 ether, and 1.25 g of acetic acid were added, and an appropriate amount of water was added to homogenize and emulsify the mixture. The solvent was removed under reduced pressure on a rotary evaporator, and the solids content of the product was adjusted to approximately 30% with water to obtain a nanosilica-reactive polyurethane crosslinked waterproofing agent.

[0049] The reaction mechanism of the preparation process of the present invention is described in combination Figure 1 The Huisgen 1,3-dipolar cycloaddition (CuAAC) reaction of azide and terminal alkyne to generate 1,2,3-triazole compounds under the catalysis of Cu+ ions is an efficient click chemistry reaction with the advantages of rapidity, high efficiency, high yield, and high selectivity. It is widely used in the modification of polymers and the preparation of nanoparticle composite materials. In order to improve the compatibility of the polyurethane-nanosilica system, the present invention combines nanosilica co-modified with an azide group / long-chain alkyl group having a high grafting rate with a reactive polyurethane matrix containing terminal alkyne groups on the side groups. By catalyzing the CuAAC click chemistry reaction, the hydrophobically modified nanosilica and the polyurethane matrix are chemically bonded, thereby greatly improving the compatibility of the nanosilica and the polyurethane matrix, and obtaining a chemically modified hydrophobic nanosilica-reactive polyurethane composite material. Due to its high affinity for fibers, the polyurethane matrix can allow the hydrophobically modified nano-silica to be uniformly adsorbed and arranged on the fibers, giving the fibers excellent waterproof properties. Moreover, because the polyurethane matrix in the present invention is a reactive polyurethane, the polyurethane-silica composite material can be wrapped or chemically bonded to the fiber substrate, making this adsorption quite washable and ultimately providing a long-lasting waterproof effect.

[0050] Example 2

[0051] The synthesis process of nano-silica modified with long-chain alkylsilane coupling agent and azidosilane coupling agent is the same as that in Example 1.

[0052] The synthesis process of N-propargyl-2,2'-dihydroxydiethylamine is the same as that in Example 1.

[0053] In a three-necked flask, 35.9 g of polycaprolactone diol (molecular weight 1000) and 39.8 g of polytetramethylene glycol (molecular weight 2000) were added, and isophorone diisocyanate (IPDI) was added. The temperature was raised to 70°C, 0.04 g of dibutyltin dilaurate was added, and the reaction was carried out for 2 to 6 hours. The free NCO content of the system was monitored by di-n-butylamine titration to the theoretical value. 5.3 g of N-propargyl-2,2'-dihydroxydiethylamine, 1.2 g of 1,3-propylene glycol and 2.8 g of 3,5-dimethylpyrazole were added. A small amount of acetone was added during the reaction to reduce the viscosity. The reaction was carried out at 70°C for 1 to 4 hours until the free NCO disappeared to obtain a reactive polyurethane.

[0054] 46g of the reactive polyurethane was placed in a three-necked flask at room temperature and purged with nitrogen. 28.8g of nanosilica modified with a long-chain alkylsilane coupling agent and an azide silane coupling agent was added and ultrasonically dispersed for 30 minutes. 0.04g of CuSO4·5H2O and 0.035g of sodium ascorbate were added and stirred for 10 hours to obtain a nanosilica-reactive polyurethane crosslinked product. 4.2g of TWEEN 80, 2.8g of isomeric tridecanol polyoxyethylene 7 ether, and 1.25g of acetic acid were added, and an appropriate amount of water was added to homogenize and emulsify the mixture. The solvent was removed under reduced pressure on a rotary evaporator, and the solids content of the product was adjusted to approximately 30% with water to obtain a nanosilica-reactive polyurethane crosslinked waterproofing agent.

[0055] Example 3

[0056] The synthesis process of nano-silica modified with long-chain alkylsilane coupling agent and azidosilane coupling agent is the same as that in Example 1. The difference between this example and Example 1 is that the hexadecyltrimethoxysilane used in Example 1 is replaced with dodecyltrimethoxysilane.

[0057] The synthesis process of N-propargyl-2,2'-dihydroxydiethylamine is the same as that in Example 1.

[0058] The formula and preparation method of the reactive polyurethane and nano-silica-reactive polyurethane cross-linking waterproofing agent are the same as those in Example 1.

[0059] Example 4

[0060] The synthesis process of nano-silica modified with long-chain alkylsilane coupling agent and azidosilane coupling agent is the same as that in Example 1. The difference between this example and Example 1 is that the hexadecyltrimethoxysilane used in Example 1 is replaced with dodecyltrimethoxysilane.

[0061] The synthesis process of N-propargyl-2,2'-dihydroxydiethylamine is the same as that in Example 1.

[0062] The formula and preparation method of reactive polyurethane and nano-silica-reactive polyurethane cross-linking waterproofing agent are the same as those in Example 2.

[0063] Comparative Example 1

[0064] Take 33.3g of dried nano-silica, ultrasonically disperse it in 1000ml of DMSO, pass nitrogen, add 66.7g of hexadecyltrimethoxysilane, ultrasonicate for 30min, stir and react at 100℃ for 24h. After the reaction is completed, cool to room temperature, wash with acetone after centrifugation, disperse it, and then centrifuge it. After vacuum drying, obtain long-chain alkylsilane coupling agent modified nano-silica.

[0065] In a three-necked flask, 73.9 g of polycarbonate diol (DUNANOL T5651, produced by Asahi Chemical Co., Ltd. of Japan) and 78.8 g of polytetramethylene glycol (molecular weight 2000) were added, and diphenylmethane diisocyanate (MDI) was added. The temperature was raised to 70°C, 0.06 g of dibutyltin dilaurate was added, and the reaction was carried out for 2 to 6 hours. The free NCO content of the system was monitored to the theoretical value by di-n-butylamine titration. 6.1 g of 1,3-propylene glycol and 2.5 g of butanone oxime were added. A small amount of acetone was added during the reaction to reduce the viscosity. The reaction was carried out at 70°C for 1 to 4 hours until the free NCO disappeared to obtain a reactive polyurethane.

[0066] At room temperature, 46 g of the reactive polyurethane was placed in a three-necked flask and purged with nitrogen. 28.8 g of nanosilica modified with a long-chain alkylsilane coupling agent was added and ultrasonically dispersed for 30 minutes. Then, 4.2 g of TWEEN 80, 2.8 g of isomeric tridecanol polyoxyethylene 7 ether, and 1.25 g of acetic acid were added. An appropriate amount of water was added and homogenized to emulsify the mixture. The solvent was removed under reduced pressure on a rotary evaporator, and the solids content of the product was adjusted to approximately 30% with water to obtain a nanosilica-reactive polyurethane composite waterproofing agent.

[0067] Comparative Example 2

[0068] Take 33.3g of dried nano-silica, ultrasonically disperse it in 1000ml of DMSO, pass nitrogen, add 66.7g of hexadecyltrimethoxysilane, ultrasonicate for 30min, stir and react at 100℃ for 24h. After the reaction is completed, cool to room temperature, centrifuge and wash with acetone in turn, disperse and centrifuge, and vacuum dry to obtain long-chain alkylsilane coupling agent modified nano-silica.

[0069] In a three-necked flask, 35.9 g of polycaprolactone diol (molecular weight 1000) and 39.8 g of polytetramethylene glycol (molecular weight 2000) were added, and isophorone diisocyanate (IPDI) was added. The temperature was raised to 70°C, and 0.04 g of dibutyltin dilaurate was added. The reaction was continued for 2 to 6 hours. The free NCO content of the system was monitored by di-n-butylamine titration to the set value. 3.9 g of 1,3-propylene glycol and 2.9 g of 3,5-dimethylpyrazole were added. A small amount of acetone was added during the reaction to reduce the viscosity. The reaction was continued at 70°C for 1 to 4 hours until the free NCO disappeared to obtain a reactive polyurethane.

[0070] At room temperature, 46 g of the reactive polyurethane was placed in a three-necked flask and purged with nitrogen. 28.8 g of nanosilica modified with a long-chain alkylsilane coupling agent was added and ultrasonically dispersed for 30 minutes. Then, 4.2 g of TWEEN 80, 2.8 g of isomeric tridecanol polyoxyethylene 7 ether, and 1.25 g of acetic acid were added. An appropriate amount of water was added and homogenized to emulsify the mixture. The solvent was removed under reduced pressure on a rotary evaporator, and the solids content of the product was adjusted to approximately 30% with water to obtain a nanosilica-reactive polyurethane cross-linked waterproofing agent.

[0071] Test methods and results

[0072] The fluorine-free water repellents of Examples 1-4 and Comparative Examples 1 and 2 were diluted with deionized water to a concentration of 30 g / L. The pH of the working solution was adjusted to 4-6 with acetic acid. The products were subjected to a one-dip-one-pad process, dried at 110°C, and heat-treated at 170°C for 60 seconds. After standing for 2 hours, they were subjected to a water spray test according to AATCC 22-2010. The water repellency was measured after the initial wash cycle, 10 cycles, and 20 cycles of home washing (10HL and 20HL). The results are shown in Table 1.

[0073]

[0074] (Table 1)

[0075] A higher score indicates better waterproof performance. As can be seen from Table 1, the waterproof performance of the present invention is excellent and more durable.

[0076] In other embodiments:

[0077] The modified nano-silica of the present invention comprises 85-96% by weight of a solvent, 1-6% by weight of silica, 1-4% by weight of a silane coupling agent, and 2-5% by weight of a long carbon chain silane coupling agent, the total weight percentage of each raw material being 100%. The long carbon chain silane coupling agent is one or a combination of two or more of dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

[0078] The reactive polyurethane of the invention consists of polyisocyanate, polyol monomer, N-propargyl-2,2'-dihydroxydiethylamine, chain extender and end-capping agent, wherein the molar ratio of polyisocyanate to polyol monomer is 2.5-1.2:1. Polyisocyanate is one or a mixture of two or more substances with two or more isocyanate groups, including but not limited to one or more of aromatic or aliphatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), polymethylene polyphenyl isocyanate (PAPI), dicyclohexylmethane diisocyanate (H12MDI), xylylene diisocyanate (XDI), tetramethyl-m-xylylene diisocyanate (TMXDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), and one or more mixtures of derivatives such as dimers, trimers, biuret, carbodiimide-modified, propylene glycol-modified, and reaction products with trimethylolpropane of the foregoing diisocyanates. Preferred are one or more of diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), and their derivatives. The polyol monomer is one or more of polyester polyol, polycarbonate diol, and polytetramethylene glycol. The chain extender is one or more of 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, dimethylolpropionic acid, dimethylolbutyric acid, diethanolamine, triethanolamine, N-methyldiethanolamine, ethylenediamine, hexamethylenediamine, isophoronediamine, diethylenetriamine, and triethylenetetramine. The end-capping agent is phenol, caprolactam, acetone oxime, methyl ethyl ketone oxime, or 3,5-dimethylpyrazole. N-propargyl-2,2'-dihydroxydiethylamine is prepared by dropwise adding propargyl bromide to a tetrahydrofuran solution containing di(2-hydroxyethyl)amine and triethylamine at 0-5°C for 2-6 hours. After the reaction, the solution is filtered, repeatedly washed with tetrahydrofuran, and then concentrated by distillation under reduced pressure. The molar ratio of di(2-hydroxyethyl)amine to triethylamine is 1:1-3, and the molar ratio of triethylamine to propargyl bromide is 1-1.5:1.

[0079] The modified nano-silicon dioxide-reactive polyurethane cross-linked product of the invention is obtained by addition reaction of the modified nano-silicon dioxide and the reactive polyurethane.

[0080] In step S1 of the preparation method of the present invention, dried nano-silica is ultrasonically dispersed in a solvent, nitrogen is introduced, a silane azide coupling agent is added, and ultrasonication is carried out for 10 to 60 minutes. A long carbon chain silane coupling agent is then added, and the mixture is stirred and reacted at 100 to 110°C for 12 to 24 hours. The mixture is cooled to room temperature, washed multiple times, and then vacuum dried to obtain the product. The solvent is one of toluene, N,N-dimethylformamide, and dimethyl sulfoxide. The silane azide coupling agent is prepared by reacting a chlorine-containing silane coupling agent and sodium azide in a solvent under a nitrogen atmosphere, followed by multiple extractions with n-hexane, and concentrated by vacuum distillation. The reaction temperature is 100 to 110°C, and the reaction time is 12 to 24 hours. The chlorine-containing silane coupling agent is one of 3-chloropropyltrimethoxysilane or 3-chloropropyltriethoxysilane; and the reaction solvent is one of N,N-dimethylformamide and dimethyl sulfoxide.

[0081] In step S2, a polyisocyanate and a polyol monomer are reacted in a solvent to synthesize a prepolymer at a reaction temperature of 70-100°C for 3-8 hours. N-propargyl-2,2'-dihydroxydiethylamine, a chain extender, and a capping agent are then added to the prepolymer. The reaction temperature is 40-100°C for 1-4 hours until no free isocyanate remains, thereby producing a reactive polyurethane. The solvent is one of acetone, butanone, methyl isobutyl ketone, benzene, toluene, ethyl acetate, and butyl acetate.

[0082] In step S3, under a nitrogen atmosphere, long-chain alkyl and azidated modified nano-silica is added to a reactive polyurethane, ultrasonically dispersed for 30 minutes, and then copper sulfate pentahydrate and sodium ascorbate are added. The mixture is stirred and reacted under nitrogen for 6 to 12 hours to produce a modified nano-silica-reactive polyurethane cross-linked product. The copper sulfate pentahydrate is used in an amount of 0.05 to 0.1% of the reactive polyurethane, and the molar ratio of copper sulfate pentahydrate to sodium ascorbate is 1:1 to 2.0.

[0083] In step S4, the modified nano-silica-reactive polyurethane cross-linked product is mixed with an emulsifier and deionized water, and then homogenized and emulsified to obtain the product. The emulsifier is selected from one or more combinations of non-ionic and cationic surfactants. Specifically, the emulsifier is selected from non-ionic emulsifiers such as linear fatty alcohol polyoxyethylene ether, isomeric fatty alcohol polyoxyethylene ether, anhydrous sorbitan fatty acid ester, polyoxyethylene anhydrous sorbitan fatty acid ester, fatty acid glyceride, fatty acid polyglycerol ester, or one or more combinations of cationic emulsifiers such as alkylamine, alkyl tertiary amine, alkyl quaternary ammonium salt, alkyl ester quaternary ammonium salt, alkyl acyl quaternary ammonium salt and polyoxyethylene alkyl quaternary ammonium salt. The amount of the emulsifier is 10-20% of the modified nano-silica-reactive polyurethane cross-linked product.

Claims

1. A method for preparing a modified nano-silica-reactive polyurethane cross-linked waterproofing agent, characterized in that The following steps are involved: S1, generating modified nano-silica by long-chain alkyl and azide-modified nano-silica; The dried nano-silica was ultrasonically dispersed in a solvent, nitrogen was introduced, a silane azide coupling agent was added, ultrasonication was performed for 10 to 60 minutes, a long carbon chain silane coupling agent was added, and the mixture was stirred at 100 to 110°C for 12 to 24 hours. The mixture was cooled to room temperature, washed, and dried to obtain the modified nano-silica. S2. preparing reactive polyurethane; The reactive polyurethane comprises a polyisocyanate, a polyol monomer, N-propargyl-2,2'-dihydroxydiethylamine, a chain extender, and a capping agent, wherein the molar ratio of the polyisocyanate to the polyol monomer is 2.5-1.2:

1. In step S2, the polyisocyanate and the polyol monomer react in a solvent to synthesize a prepolymer, the reaction temperature is 70-100° C., and the reaction time is 3-8 hours. Then, N-propargyl-2,2'-dihydroxydiethylamine, the chain extender, and the capping agent are added to the prepolymer, the reaction temperature is 40-100° C., and the reaction time is 1-4 hours until no free isocyanate remains, thereby obtaining the reactive polyurethane. S3, subjecting the modified nano-silica prepared in step S1 to an addition reaction with the reactive polyurethane prepared in step S2 to obtain a modified nano-silica-reactive polyurethane cross-linked product; Under a nitrogen atmosphere, the modified nano-silica was added to the reactive polyurethane and ultrasonically dispersed for 30 minutes. Then, copper sulfate pentahydrate and sodium ascorbate were added, and the mixture was stirred and reacted under nitrogen for 6 to 12 hours to obtain a modified nano-silica-reactive polyurethane cross-linked product. The amount of copper sulfate pentahydrate was 0.05 to 0.1% of the reactive polyurethane, and the molar ratio of copper sulfate pentahydrate to sodium ascorbate was 1:1 to 2.

0. S4. The modified nano-silica-reactive polyurethane cross-linked product obtained in step S3 is subjected to solvent removal and emulsification to obtain a modified nano-silica-reactive polyurethane cross-linked waterproofing agent.

2. The preparation method according to claim 1, wherein: The silane azide coupling agent is prepared by reacting a chlorosilane coupling agent and sodium azide in a solvent under a nitrogen atmosphere, extracting with n-hexane, and concentrating by reduced pressure distillation.

3. The preparation method according to claim 2, wherein: In step S4, the modified nano-silica-reactive polyurethane cross-linked product is mixed with an emulsifier and deionized water, and then homogenized and emulsified to obtain a product.

4. The preparation method according to claim 3, wherein: The emulsifier is selected from one or more combinations of nonionic and cationic surfactants.

5. The preparation method according to claim 4, characterized in that: The emulsifier is selected from one or more combinations of linear fatty alcohol polyoxyethylene ether, isomeric fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid glyceride, fatty acid polyglyceride, alkylamine, alkyl quaternary ammonium salt and polyoxyethylene alkyl quaternary ammonium salt, wherein the amount of the emulsifier is 10-20% of the modified nano-silica-reactive polyurethane cross-linked product.

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