Fluoride-free waterproof agent and preparation method thereof

Abstract

The invention discloses a fluoride-free waterproof agent and a preparation method thereof, and relates to the technical field of waterproof agents. The preparation method comprises the following steps: adding nano silicon dioxide into acrylate-terminated polydimethylsiloxane, octadecyl methacrylate and methacryloyloxypropyltrimethoxysilane, mixing, and dropwise adding azodiisobutyronitrile to react, so as to obtain an organic-inorganic hybrid prepolymer acetone solution; the preparation method comprises the following steps: reacting polycaprolactone glycol, isophorone diisocyanate and dibutyltin dilaurate to prepare a polyurethane prepolymer, cooling, adding dimethylolpropionic acid and acetone for a continuous reaction, cooling, neutralizing and emulsifying to obtain a waterborne polyurethane dispersion, adding the hybrid prepolymer for emulsification, adding methyl methacrylate and hydroxyethyl acrylate for a reaction, cooling, neutralizing and emulsifying to obtain the waterborne polyurethane dispersion. Finally adding glycerol polyglycidyl ether to react to obtain a composite emulsion; adding a defoaming agent, a flatting agent and a sterilizing agent into the composite emulsion to obtain the fluoride-free waterproof agent. The waterproof agent has lasting waterproof performance after acting on the fabric.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waterproofing agents, in particular to a fluorine-free waterproofing agent and a preparation method thereof. BACKGROUND

[0002] In the field of textiles, waterproofing agents are an important class of auxiliaries that can impart water-repellent properties to fabrics, broadening their application scenarios. Fluorine-containing waterproofing agents once dominated the market with their outstanding water-repellent effects, but the perfluorinated compounds in them have biological enrichment and can have a lasting impact on the environment, which does not comply with the basic national policy of ecological civilization construction. Therefore, the development of fluorine-free waterproofing agents has become a hot topic in the industry.

[0003] Fluorine-free waterproofing agents are environmentally friendly textile auxiliaries that do not contain fluorocarbon resins. They are gradually gaining market recognition due to their good water-repellent properties and lack of harm to the environment and human health. Their main types include paraffin, organosilicon, acrylic, polyurethane, and dendrimer polymers, among others. For example, organosilicon fluorine-free waterproofing agents can impart good water-repellent properties to fabrics due to the low surface tension of the siloxane structure, and the finished fabric has a soft feel, light hand marks, and less color change. Polyurethane fluorine-free waterproofing agents have good comprehensive performance, can form a very soft film, and can improve the water-repellent properties and wash resistance of the finished fabric, and improve the hand mark phenomenon after finishing.

[0004] Although fluorine-free waterproofing agents have many advantages such as environmental friendliness, their poor durability and stability after being applied to fabrics remain a major problem. In terms of wash resistance, the protective structure formed on the fabric surface by fluorine-free waterproofing agents can be easily damaged after multiple washes, resulting in a significant decrease in water-repellent properties. For example, some fluorine-free waterproofing agents can only achieve ideal water-repellent properties after 10 washes. On the other hand, during daily wear and use, the combination of fluorine-free waterproofing agents and fabric fibers may weaken when the fabric is subjected to external forces such as friction and stretching, thereby affecting the durability and stability of water-repellent properties. SUMMARY

[0005] The present application aims to provide a fluorine-free waterproofing agent and a preparation method thereof to solve the technical problems raised in the background art. The fluorine-free waterproofing agent prepared by the present application has high bonding strength with the fabric, thereby imparting the fabric with durable and stable hydrophobic properties.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A preparation method of a fluorine-free waterproofing agent, comprising the following steps: S1, add nano-silica into n-butanol to form a suspension, then add acrylate-terminated polydimethylsiloxane, methacrylate octadecyl ester and gamma-methacryloyloxypropyl trimethoxysilane, stir to mix uniformly, then drop azobisisobutyronitrile to react, to obtain an organic-inorganic hybrid prepolymer solution, then distill n-butanol, and add acetone to dilute, to obtain an organic-inorganic hybrid prepolymer acetone solution; S2, under nitrogen protection, mix polycaprolactone diol, isophorone diisocyanate and dibutyl tin dilaurate to react to form a polyurethane prepolymer, then cool, add dimethylolpropionic acid and acetone to continue to react, then cool, add triethylamine to neutralize, then add deionized water to emulsify, to obtain an aqueous polyurethane dispersion, then add the organic-inorganic hybrid prepolymer acetone solution, after emulsification and dispersion, add methyl methacrylate, hydroxyethyl acrylate and potassium persulfate to heat to react, finally add glycerol polyglycidyl ether to react, to obtain a composite emulsion; S3, add defoaming agent, leveling agent and bactericide to the composite emulsion, mix uniformly, adjust pH value with ammonia water, to obtain a fluorine-free waterproof agent.

[0007] In the technical scheme of the present application, on the one hand, by using high-reactivity acrylate-terminated polysiloxane, long-chain alkyl acrylate and gamma-methacryloyloxypropyl trimethoxysilane for efficient copolymerization, the low-surface-energy silicone molecular chain is firmly integrated into the polymer skeleton, providing the extremely low surface energy required for superhydrophobicity. And by reacting nano-silica with gamma-methacryloyloxypropyl trimethoxysilane to graft nano-silica onto the polymer network, an organic-inorganic hybrid structure is constructed. These rigid nanoparticles can be uniformly distributed on the film surface during subsequent film formation, forming a stable micro-nano scale rough structure, achieving high static contact angle and excellent initial water repellency. At the same time, these covalently linked nano-silica act as strong anchor points, greatly enhancing the mechanical strength, wear resistance and tear resistance of the paint film, enabling it to withstand friction and washing in daily use, effectively delaying the decay of waterproof performance due to film wear from a physical point of view.

[0008] On the other hand, by synthesizing a polyurethane prepolymer containing a carboxyl hydrophilic group, forming a water-based dispersion with excellent stability after emulsification, and uniformly dispersing the organic-inorganic hybrid prepolymer acetone solution in the polyurethane system by high-speed shearing emulsification, then introducing the acrylic monomer for free radical copolymerization, finally forming a PU / PA interpenetrating network structure. Among them, the polyurethane segment gives the paint film excellent elasticity and flexibility, so it can withstand repeated bending of the fabric; the acrylic segment provides high adhesion and rigidity, ensuring that the paint film can adhere tightly to the fiber surface. The multifunctional epoxy crosslinking agent glycerol polyglycidyl ether can react with the carboxyl and hydroxyl groups on the polyurethane and acrylic segments to form a high-density three-dimensional covalent network. This network firmly locks the hydrophobic segments of the organic-inorganic hybrid prepolymer and nano-silica particles in it, greatly improving the chemical resistance (such as soap washing resistance, acid and alkali resistance) and swelling resistance of the paint film, further improving the water resistance and durability of the fabric coating. For example Figure 1 The SEM image of the surface of the fabric treated with the waterproofing agent of the present application shows that the surface of the fabric fibers presents a rough structure.

[0009] Preferably, in step S1, the nano-silica is subjected to a modification treatment, including the following steps: The nano-silica is dispersed in a mixed solution of ethanol and water, stirred uniformly, then γ-glycidoxypropyltrimethoxysilane is added, heated and reacted, after the reaction is completed, polyether amine is added, heated and reacted, after the reaction is completed, centrifugal separation, washing and drying are performed, and the product is obtained.

[0010] In the technical solution of the present application, through in-depth research by the team of the present application, it is found that because nano-silica is a rigid inorganic particle, the thermal expansion coefficient and elastic modulus between it and the surrounding organic polyurethane-acrylate organic polymer matrix do not match. Under external stress (such as fabric bending, friction, thermal cycling), micro-cracks and defects are easily generated at the interface. These micro-cracks will further expand and connect to the polymer matrix with lower strength, eventually forming a macro-crack network, destroying the micro-nano structure of the coating, and causing the hydrophobicity and wear resistance to drop sharply, which severely limits the durability of the waterproof performance. To further solve this technical problem, the nano-silica is pre-modified. With nano-silica as the core, first, γ-glycidoxypropyltrimethoxysilane is used to introduce high-reactivity epoxy groups on the surface of the nano-silica through hydrolysis and condensation reaction; then, the amino group of the polyether amine reacts with the epoxy group to graft the long-chain flexible polyether segment onto the surface of the silica through stable covalent bonds, finally forming a core-shell structure. The flexible polyether shell layer acts as a stress buffer layer, establishing a continuous transition of modulus and thermal expansion coefficient between the inorganic core and the organic matrix, fundamentally inhibiting the initiation and expansion of interface micro-cracks, thereby significantly improving the durability of the composite system, greatly reducing the generation of interface micro-cracks, and directly improving the hydrophobicity and durability of the coating.

[0011] As preferred, the mass ratio of the nanosilica and the polyetheramine is 10:3-5.

[0012] As preferred, in the step S1, the mass ratio of the acrylate-terminated polydimethylsiloxane, the stearyl methacrylate and the gamma-methacryloxypropyltrimethoxysilane is 20:13-16:8-12.

[0013] As preferred, in the step S2, the mass ratio of the polycaprolactone diol and the isophorone diisocyanate is 3:1-2.

[0014] As preferred, in the step S2, the mass ratio of the polycaprolactone diol and the dimethylolpropionic acid is 10:1-3.

[0015] As preferred, in the step S2, the mass ratio of the methyl methacrylate and the hydroxyethyl acrylate is 5:1-3.

[0016] As preferred, in the step S3, the defoaming agent is an organosilicon defoaming agent.

[0017] As preferred, in the step S3, the leveling agent is a polyether-modified siloxane leveling agent.

[0018] A fluorine-free waterproofing agent prepared by the method of the above claim.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1. By constructing a polyurethane-acrylate interpenetrating network structure and using an epoxy crosslinking agent to form a high-density three-dimensional covalent network, the organic silicon / nanosilica hybrid prepolymer is firmly locked, greatly improving the wear resistance, wash resistance and anti-physical grinding ability of the coating, thereby realizing the durability of the waterproof effect.

[0020] 2. The nanosilica is modified by polyetheramine to form a core-shell structure, and a soft and elastic interface layer is constructed on the surface, effectively buffering the mismatch between the thermal expansion coefficient and the elastic modulus between the inorganic nanoparticles and the organic polymer matrix, fundamentally inhibiting the generation and expansion of interface microcracks, greatly improving the flexibility, adhesion and mechanical strength of the composite coating, and further improving the hydrophobicity, durability and stability. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 SEM image of the surface of the fabric treated with the waterproofing agent of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] Embodiment 1

[0024] A preparation method of a fluorine-free waterproof agent, comprising the following steps: Step 1: 10.0 g of nano-silica is dispersed in a mixed solution composed of 100 mL of ethanol and 20 mL of deionized water, and stirred at a speed of 500 rpm in a three-necked flask for 30 min to make it fully dispersed. Then 3.5 g of γ-glycidoxypropyltrimethoxysilane is added, the temperature is raised to 70 ℃, and the reaction is carried out under nitrogen protection for 3 h. Then 4.5 g of polyetheramine D230 is added, the temperature is raised to 80 ℃, and the reaction is continued for 4 h. After the reaction is completed, the mixture is centrifuged, washed with ethanol for three times, and dried in a vacuum drying box at 60 ℃ for 12 h to obtain modified nano-silica powder.

[0025] 5.0 g of the modified nano-silica powder is dispersed in 50 mL of n-butanol, and ultrasonic treatment is carried out for 30 min to form a stable suspension. Then 20.0 g of acrylate-terminated polydimethylsiloxane (Mn=5000), 15.0 g of methacrylate octadecyl ester and 11.0 g of γ-methacryloyloxypropyltrimethoxysilane are sequentially added, and the mixture is stirred at 75 ℃ and at a speed of 300 rpm for 30 min. Then an initiator solution composed of 0.3 g of azobisisobutyronitrile dissolved in 12 mL of n-butanol is slowly dropped by using a constant-pressure dropping funnel, the dropping time is controlled for 30 min, and after the dropping is completed, the reaction is continued at 75 ℃ for 6 h to obtain an organic-inorganic hybrid prepolymer solution. Finally, n-butanol is removed by distillation at 60 ℃ and under a pressure of -0.09 MPa by using a rotary evaporator, 30 mL of acetone is added for dilution to obtain a hybrid prepolymer acetone solution, and the solution is sealed for standby use.

[0026] Step 2: In a four-necked flask equipped with a condenser, thermometer and mechanical stirrer, under nitrogen protection, 30.0 g polycaprolactone diol (Mn=2000), 18.0 g isophorone diisocyanate and 0.04 g dibutyl tin dilaurate were sequentially added, and the reaction was stirred at 200 rpm for 2.5 h at 85°C. The system was cooled to 60°C, 8.0 g dimethylol propionic acid and 20 mL acetone diluent were added, and the reaction was continued at 60°C for 2 h. Then it was cooled to 35°C, 4.0 g triethylamine was added for neutralization for 15 min, and then 120 mL deionized water was slowly added under the stirring of a high-speed disperser at 10000 rpm for emulsification. The emulsification process lasted for 40 min to obtain an aqueous polyurethane dispersion. The hybrid prepolymer acetone solution was added to the system, and emulsified at 12000 rpm for 15 min. Then 5.0 g methyl methacrylate, 2.5 g hydroxyethyl acrylate and 0.2 g potassium persulfate (dissolved in 10 mL water) were added. The temperature was slowly increased to 80°C, and the reaction was continued for 4 h to complete the free radical copolymerization. Finally, 2.0 g glycerol polyglycidyl ether was added, and the reaction was continued at 75°C for 2 h to complete the crosslinking to obtain a composite emulsion.

[0027] Step 3: The obtained composite emulsion was sequentially added with 1.0 g silicone defoaming agent (BYK-024), 1.5 g polyether modified silicone leveling agent (BYK-346) and 0.5 g isothiazolinone bactericide (BIT-20) under the stirring condition at 300 rpm. After the auxiliary agents were fully dispersed by continuous stirring for 30 min, the pH value of the system was slowly adjusted to the range of 7.5-8.0 by using appropriate amount of ammonia water. Finally, the product was filtered through a 200 mesh nylon filter cloth to obtain a fluorine-free waterproof agent.

[0028] Example 2

[0029] A method for preparing a fluorine-free waterproof agent, comprising the following steps: Step 1: 10.0 g nano-silica was dispersed in a mixed solution composed of 100 mL ethanol and 20 mL deionized water, and stirred at a speed of 500 rpm for 30 min in a three-necked flask to fully disperse it. Then 3.5 g γ-glycidoxypropyltrimethoxysilane was added, and the temperature was increased to 70°C. The reaction was carried out under nitrogen protection for 3 h, and then 3.5 g polyether amine D230 was added. The temperature was increased to 80°C, and the reaction was continued for 4 h. After the reaction was completed, the mixture was centrifuged, washed with ethanol for three times, and then dried in a vacuum drying oven at 60°C for 12 h to obtain a modified nano-silica powder.

[0030] Modified nano-silica powder 5.0 g was dispersed in 50 mL of n-butanol, and ultrasonic treatment was performed for 30 min to form a stable suspension. Then, 20.0 g of acrylate-terminated polydimethylsiloxane (Mn=5000), 14.0 g of methacrylate octadecyl ester, and 9.0 g of γ-methacryloyloxypropyl trimethoxysilane were sequentially added, and the mixture was stirred at 300 rpm for 30 min at 75°C. Then, an initiator solution composed of 0.3 g of azobisisobutyronitrile dissolved in 12 mL of n-butanol was slowly added dropwise using a constant pressure dropping funnel, and the dropping time was controlled for 30 min. After the dropping was completed, the reaction was continued at 75°C for 6 h to obtain an organic-inorganic hybrid prepolymer solution. Finally, n-butanol was removed by distillation at 60°C and -0.09 MPa using a rotary evaporator, and 30 mL of acetone was added to dilute the hybrid prepolymer solution to obtain a hybrid prepolymer acetone solution, which was sealed for later use.

[0031] Step 2: In a four-necked flask equipped with a condenser, a thermometer, and a mechanical stirrer, nitrogen was introduced for protection, and 30.0 g of polycaprolactone diol (Mn=2000), 13.0 g of isophorone diisocyanate, and 0.04 g of dibutyltin dilaurate were sequentially added. The reaction was stirred at 200 rpm for 2.5 h at 85°C, the system was cooled to 60°C, 5.0 g of dimethylol propionic acid and 20 mL of acetone diluent were added, and the reaction was continued at 60°C for 2 h. Then, the temperature was lowered to 35°C, 4.0 g of triethylamine was added for neutralization for 15 min, and then 120 mL of deionized water was slowly added under the stirring of a high-speed disperser at 10000 rpm for emulsification. The emulsification process lasted for 40 min to obtain an aqueous polyurethane dispersion. The hybrid prepolymer acetone solution was added to the system, and the emulsification was performed at 12000 rpm for 15 min. Then, 5.0 g of methyl methacrylate, 1.5 g of hydroxyethyl acrylate, and 0.2 g of potassium persulfate (dissolved in 10 mL of water) were added. The temperature was slowly increased to 80°C, and the reaction was continued for 4 h to complete the free radical copolymerization. Finally, 2.0 g of glycerol polyglycidyl ether was added, and the reaction was continued at 75°C for 2 h to complete the crosslinking, thereby obtaining a composite emulsion.

[0032] Step 3: The obtained composite emulsion was sequentially added with 1.0 g of silicone antifoaming agent (BYK-024), 1.5 g of polyether-modified siloxane leveling agent (BYK-346), and 0.5 g of isothiazolinone bactericide (BIT-20) under the stirring condition at 300 rpm. After the auxiliary agents were fully dispersed by continuous stirring for 30 min, the pH value of the system was slowly adjusted to the range of 7.5-8.0 using an appropriate amount of ammonia water. Finally, the product was filtered through a 200-mesh nylon filter cloth to obtain a fluorine-free waterproof agent.

[0033] Example 3

[0034] A method for preparing a fluorine-free waterproof agent, comprising the following steps: Step 1: 10.0 g of nano-silica was dispersed in a mixed solution of 100 mL of ethanol and 20 mL of deionized water in a three-necked flask, and stirred at a speed of 500 rpm for 30 min to make it fully dispersed. Then 3.5 g of γ-glycidoxypropyltrimethoxysilane was added, and the temperature was raised to 70°C, and reacted for 3 h under nitrogen protection. Then 4.0 g of polyetheramine D230 was added, and the temperature was raised to 80°C and reacted for 4 h. After the reaction was completed, the mixture was centrifuged, washed with ethanol three times, and dried in a vacuum drying oven at 60°C for 12 h to obtain modified nano-silica powder.

[0035] 5.0 g of modified nano-silica powder was dispersed in 50 mL of n-butanol, and ultrasonic treatment was performed for 30 min to form a stable suspension. 20.0 g of acrylate-terminated polydimethylsiloxane (Mn=5000), 14.5 g of methacrylate octadecyl ester, and 10.0 g of γ-methacryloyloxypropyltrimethoxysilane were added in sequence, and the mixture was stirred at 75°C for 30 min at a speed of 300 rpm. Then an initiator solution composed of 0.3 g of azobisisobutyronitrile dissolved in 12 mL of n-butanol was slowly added dropwise using a constant pressure dropping funnel, and the dropping time was controlled for 30 min. After the dropping was completed, the reaction was continued at 75°C for 6 h to obtain an organic-inorganic hybrid prepolymer solution. Finally, n-butanol was removed by distillation at 60°C and -0.09 MPa using a rotary evaporator, and 30 mL of acetone was added to dilute to obtain a hybrid prepolymer acetone solution, which was sealed for use.

[0036] Step 2: In a four-necked flask equipped with a condenser, a thermometer, and a mechanical stirrer, nitrogen was introduced, and 30.0 g of polycaprolactone diol (Mn=2000), 15.0 g of isophorone diisocyanate, and 0.04 g of dibutyltin dilaurate were added in sequence, and the reaction was carried out at 85°C for 2.5 h at a stirring speed of 200 rpm. The system was cooled to 60°C, 6.0 g of dimethylol propionic acid and 20 mL of acetone diluent were added, and the reaction was continued at 60°C for 2 h. Then the temperature was lowered to 35°C, 4.0 g of triethylamine was added for neutralization for 15 min, and then 120 mL of deionized water was slowly added under the stirring of a high-speed disperser at 10000 rpm for emulsification. The emulsification process lasted for 40 min to obtain an aqueous polyurethane dispersion. The hybrid prepolymer acetone solution was added to the system, and emulsified at a high speed of 12000 rpm for 15 min. Then 5.0 g of methyl methacrylate, 2.0 g of hydroxyethyl acrylate, and 0.2 g of potassium persulfate (dissolved in 10 mL of water) were added. The temperature was slowly raised to 80°C, and the reaction was carried out for 4 h to complete the free radical copolymerization. Finally, 2.0 g of glycerol polyglycidyl ether was added, and the reaction was continued at 75°C for 2 h to complete the crosslinking, to obtain a composite emulsion.

[0037] Step 3: The obtained composite emulsion was added with 1.0 g silicone antifoaming agent (BYK-024), 1.5 g polyether modified siloxane leveling agent (BYK-346) and 0.5 g isothiazolinone bactericide (BIT-20) in sequence under stirring at 300 rpm. After the auxiliary agents were fully dispersed by continuous stirring for 30 min, the pH value of the system was slowly adjusted to the range of 7.5-8.0 with appropriate amount of ammonia water, and finally the product was filtered through 200 mesh nylon filter cloth to obtain the fluorine-free waterproof agent.

[0038] Example 4

[0039] A method for preparing a fluorine-free waterproof agent, comprising the following steps: Step 1: 10.0 g of nano-silicon dioxide was dispersed in a mixed solution composed of 100 mL of ethanol and 20 mL of deionized water in a three-necked flask under stirring at a speed of 500 rpm for 30 min to fully disperse. Then 3.5 g of γ-glycidyl ether oxypropyl trimethoxysilane was added, the temperature was raised to 70 °C, and the reaction was carried out under nitrogen protection for 3 h. Then 5.0 g of polyether amine D230 was added, the temperature was raised to 80 °C, and the reaction was continued for 4 h. After the reaction was completed, the mixture was centrifuged, washed with ethanol for three times, and then dried in a vacuum drying oven at 60 °C for 12 h to obtain modified nano-silicon dioxide powder.

[0040] The modified nano-silicon dioxide powder 5.0 g was dispersed in 50 mL of n-butanol, and ultrasonic treatment was carried out for 30 min to form a stable suspension. Then 20.0 g of acrylate-terminated polydimethylsiloxane (Mn=5000), 16.0 g of methyl methacrylate octadecyl ester and 12.0 g of γ-methacryloyloxypropyl trimethoxysilane were added in sequence, and the mixture was stirred at 300 rpm for 30 min at 75 °C. Then an initiator solution composed of 0.3 g of azobisisobutyronitrile dissolved in 12 mL of n-butanol was slowly added dropwise using a constant pressure dropping funnel, and the dropping time was controlled for 30 min. After the dropping was completed, the reaction was continued at 75 °C for 6 h to obtain an organic-inorganic hybrid prepolymer solution. Finally, n-butanol was removed by rotary evaporator at 60 °C and -0.09 MPa, 30 mL of acetone was added for dilution to obtain a hybrid prepolymer acetone solution, which was sealed for use.

[0041] Step 2: In a four-necked flask equipped with a condenser, thermometer and mechanical stirrer, under nitrogen protection, 30.0 g polycaprolactone diol (Mn=2000), 20.0 g isophorone diisocyanate and 0.04 g dibutyl tin dilaurate were sequentially added, and the reaction was stirred at 200 rpm for 2.5 h at 85°C. The system was cooled to 60°C, 9.0 g dimethylol propionic acid and 20 mL acetone diluent were added, and the reaction was continued at 60°C for 2 h. Then it was cooled to 35°C, 4.0 g triethylamine was added for neutralization for 15 min, and then 120 mL deionized water was slowly added under the stirring of a high-speed disperser at 10000 rpm for emulsification. The emulsification process lasted for 40 min to obtain an aqueous polyurethane dispersion. The hybrid prepolymer acetone solution was added to the system, and emulsified at 12000 rpm for 15 min. Then 5.0 g methyl methacrylate, 3.0 g hydroxyethyl acrylate and 0.2 g potassium persulfate (dissolved in 10 mL water) were added. The temperature was slowly increased to 80°C, and the reaction was continued for 4 h to complete the free radical copolymerization. Finally, 2.0 g glycerol polyglycidyl ether was added, and the reaction was continued at 75°C for 2 h to complete the crosslinking to obtain a composite emulsion.

[0042] Step 3: The obtained composite emulsion was sequentially added with 1.0 g silicone defoaming agent (BYK-024), 1.5 g polyether modified silicone leveling agent (BYK-346) and 0.5 g isothiazolinone bactericide (BIT-20) under the stirring condition at 300 rpm. After the auxiliary agents were fully dispersed by continuous stirring for 30 min, the pH value of the system was slowly adjusted to the range of 7.5-8.0 by using appropriate amount of ammonia water. Finally, the product was filtered through a 200 mesh nylon filter cloth to obtain a fluorine-free waterproof agent.

[0043] Example 5

[0044] A method for preparing a fluorine-free waterproof agent, comprising the following steps: Step 1: 10.0 g nano-silica was dispersed in a mixed solution composed of 100 mL ethanol and 20 mL deionized water, and stirred at a speed of 500 rpm for 30 min in a three-necked flask to fully disperse it. Then 3.5 g γ-glycidoxypropyltrimethoxysilane was added, and the temperature was increased to 70°C. The reaction was carried out under nitrogen protection for 3 h, and then 3.0 g polyether amine D230 was added. The temperature was increased to 80°C, and the reaction was continued for 4 h. After the reaction was completed, the mixture was centrifuged, washed with ethanol for three times, and then dried in a vacuum drying oven at 60°C for 12 h to obtain a modified nano-silica powder.

[0045] Take modified nano-silica powder 5.0 g dispersed in 50 mL of n-butanol, ultrasonic treatment for 30 min to form a stable suspension, sequentially add 20.0 g of acrylate-terminated polydimethylsiloxane (Mn=5000), 13.0 g of methacrylate octadecyl ester and 8.0 g of γ-methacryloyloxypropyl trimethoxysilane, stir the mixture at 75°C under 300 rpm for 30 min. Then use a constant pressure dropping funnel to slowly drop the initiator solution composed of 0.3 g of azobisisobutyronitrile dissolved in 12 mL of n-butanol, control the dropping time for 30 min, after dropping, continue to react at 75°C for 6 h, to obtain an organic-inorganic hybrid prepolymer solution. Finally, remove n-butanol by rotary evaporator at 60°C, -0.09 MPa, add 30 mL of acetone to dilute to obtain a hybrid prepolymer acetone solution, seal for use.

[0046] Step 2: In a four-necked flask equipped with a condenser, thermometer and mechanical stirrer, protect with nitrogen, sequentially add 30.0 g of polycaprolactone diol (Mn=2000), 10.0 g of isophorone diisocyanate and 0.04 g of dibutyltin dilaurate, stir at 200 rpm for 2.5 h at 85°C, cool the system to 60°C, add 3.0 g of dimethylol propionic acid and 20 mL of acetone diluent, keep at 60°C and continue to react for 2 h. Then cool to 35°C, add 4.0 g of triethylamine to neutralize the reaction for 15 min, then slowly add 120 mL of deionized water under high-speed dispersion machine 10000 rpm for emulsification, the emulsification process lasts for 40 min to obtain an aqueous polyurethane dispersion. Add the hybrid prepolymer acetone solution to the system, emulsify at 12000 rpm for 15 min, then add 5.0 g of methyl methacrylate, 1.0 g of hydroxyethyl acrylate and 0.2 g of potassium persulfate (dissolved in 10 mL of water). Slowly heat to 80°C, react for 4 h to complete the free radical copolymerization, finally add 2.0 g of glycerol polyglycidyl ether, continue to react at 75°C for 2 h to complete the crosslinking, to obtain a composite emulsion.

[0047] Step 3: Add 1.0 g of silicone defoamer (BYK-024), 1.5 g of polyether modified siloxane leveling agent (BYK-346) and 0.5 g of isothiazolinone bactericide (BIT-20) to the obtained composite emulsion under stirring at 300 rpm. After stirring for 30 min to make the additives fully dispersed, slowly adjust the pH value of the system to the range of 7.5-8.0 with appropriate amount of ammonia water, finally filter the product through a 200 mesh nylon filter cloth to obtain a fluorine-free waterproof agent.

[0048] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the fluorine-free waterproof agent preparation process lacks Step 1, and no hybrid prepolymer acetone solution is added in Step 2.

[0049] Comparative Example 2: Comparative Example 2 differs from Example 1 in that Step 2 is missing in the preparation of the fluorine-free water repellent agent, and the hybrid pre-polymer acetone solution is replaced by the composite emulsion in Step 3.

[0050] Comparative Example 3: Comparative Example 3 differs from Example 1 in that the nano-silica is not modified in Step 1 in the preparation of the fluorine-free water repellent agent.

[0051] Performance Test: 1. Hydrophobicity Test: Static contact angle was tested by using a contact angle meter with the sessile drop method. Before testing, the fluorine-free water repellent agent was mixed with tap water to prepare a 20 g / L working solution. The working solution was coated on pure cotton twill fabric (specification: 21 x 21 count, 128 x 68 ends / inch) by padding (pick-up rate 80%) and dried at 120°C for 3 min and cured at 150°C for 2 min. When testing the static contact angle, 5 μL of deionized water was added to 3 randomly selected points on the fabric surface, and the reading was taken after the droplet was stable for 10 s. The average value was taken. The larger the contact angle, the better the water repellency. The test results are shown in Table 1.

[0052] 2. Water Washing Resistance Test: The water washing test was performed according to the ISO 6330-2012 standard. A domestic washing machine was used (program: standard washing, water temperature 40 ± 2°C, detergent: non-phosphorus washing powder 2 g / L, bath ratio 1:20). After 20 times of washing (100°C drying for 10 min after each washing), the static contact angle was measured according to the previous hydrophobicity test method. The smaller the decrease in the static contact angle, the stronger the water washing resistance. The test results are shown in Table 1.

[0053] 3. Abrasion Resistance Test: The abrasion resistance test was performed according to the GB / T 21196.2-2007 standard using a Martindale abrasion tester with a load of 12 kPa and standard wool cloth as the abrasive. After a total of 500 friction times, the static contact angle was measured on the abrasion area, and the contact angle retention rate was calculated as “contact angle after abrasion / contact angle before abrasion x 100%”. The higher the retention rate, the better the abrasion resistance. The test results are shown in Table 1.

[0054] Table 1:

[0055] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for part of the technical features, and any modification, equivalent substitution, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a fluorine-free water repellent, characterized by comprising the steps of, It comprises the following steps: S1, adding nano-silica into n-butanol to form a suspension, then adding acrylate-terminated polydimethylsiloxane, methacrylate octadecyl ester and gamma-methacryloyloxypropyl trimethoxysilane, stirring to mix uniformly, then adding azobisisobutyronitrile dropwise to react, obtaining an organic-inorganic hybrid prepolymer solution, then distilling n-butanol, adding acetone to dilute, obtaining an organic-inorganic hybrid prepolymer acetone solution; S2, under nitrogen protection, mixing polycaprolactone diol, isophorone diisocyanate and dibutyl tin dilaurate to react to form a polyurethane prepolymer, then cooling, adding dimethylol propionic acid and acetone to continue to react, then cooling, adding triethylamine to neutralize, then adding deionized water to emulsify, obtaining an aqueous polyurethane dispersion, then adding the organic-inorganic hybrid prepolymer acetone solution, after emulsifying and dispersing, adding methyl methacrylate, hydroxyethyl acrylate and potassium persulfate to heat and react, finally adding glycerol polyglycidyl ether to react, obtaining a composite emulsion; S3, adding a defoaming agent, a leveling agent and a fungicide into the composite emulsion to mix uniformly, adjusting the pH value with ammonia water, obtaining a fluorine-free waterproof agent.

2. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S1, the nano-silica is subjected to a modification treatment, comprising the following steps: dispersing the nano-silica in a mixed solution of ethanol and water, stirring uniformly, then adding gamma-glycidyl ether oxypropyl trimethoxysilane, heating to react, after the reaction is completed, adding polyether amine to heat and react, after the reaction is completed, centrifuging, washing and drying to obtain the nano-silica.

3. The method for preparing a fluorine-free waterproofing agent according to claim 2, characterized in that, The mass ratio of the nano-silica to the polyether amine is 10:3-5.

4. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S1, the mass ratio of the acrylate-terminated polydimethylsiloxane, the methacrylate octadecyl ester and the gamma-methacryloyloxypropyl trimethoxysilane is 20:13-16:8-12.

5. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S2, the mass ratio of the polycaprolactone diol to the isophorone diisocyanate is 3:1-2.

6. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S2, the mass ratio of the polycaprolactone diol to the dimethylol propionic acid is 10:1-3.

7. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S2, the mass ratio of the methyl methacrylate to the hydroxyethyl acrylate is 5:1-3.

8. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S3, the defoaming agent is an organic silicon defoaming agent.

9. The method for preparing a fluorine-free waterproofing agent according to claim 1, characterized in that, In the step S3, the leveling agent is a polyether modified siloxane leveling agent.

10. A fluorine-free water repellent agent characterized by comprising: Prepared by the method of any one of claims 1-9.

Images