Modified nano silicon dioxide fluoride-free waterproof oil-proof finishing agent and preparation method thereof

Abstract

The invention discloses a modified nano silicon dioxide fluoride-free waterproof oil-proof finishing agent and a preparation method thereof. The preparation method of the modified nano silicon dioxide fluoride-free finishing agent provided by the invention comprises the following steps: mixing nano SiO2 with a silane coupling agent, and carrying out grafting modification to obtain modified nano SiO2; mixing the obtained modified nano SiO2 with a styrene compound and benzoyl peroxide, and carrying out addition polymerization reaction, so as to obtain PS-SCA-SiO2; and mixing the PS-SCA-SiO2 with an emulsifier, and emulsifying to obtain the modified nano silicon dioxide fluoride-free finishing agent. According to the method provided by the invention, the preparation process is easy to control, and the waterproof and oil-proof modified nano SiO2 is finished on the fabric through chemical crosslinking and valence bond combination, so that the finished fabric has excellent waterproof and oil-proof effects and washing resistance.

Description

Technical Field

[0001] This invention relates to the field of textile auxiliaries technology, and in particular to a modified nano-silica (SiO2) fluorine-free waterproof and oil-repellent finishing agent and its preparation method. Background Technology

[0002] For a long time, the highly fluorinated structures of various perfluorinated and polyfluoroalkyl compounds (PFAS) have possessed excellent hydrophobic and lipophilic properties, making them widely used as finishing agents to provide products with superior water and oil repellency. However, due to the extremely high thermal and chemical stability of PFAS, they can accumulate in the environment and in organisms, posing significant potential hazards to human health and the environment. Therefore, the United States, the European Union, China, Japan, and other countries have successively issued relevant policies, classifying fluorocarbons as pollutants. The production and use of PFAS will be restricted or even completely prohibited in various countries to protect health and safety. Researching and developing green, environmentally friendly, fluorine-free water and oil repellent finishing agents is an inevitable trend.

[0003] Currently, polysiloxanes are among the most studied fluorine-free waterproof and oil-repellent agents. They are common low-surface-energy polymers whose backbones are composed of long silicon-oxygen bonds. Due to their large bond angles, these bonds are easily rotated, resulting in a highly compliant molecule. Polysiloxanes also exhibit low intermolecular forces, contributing to their low surface energy. Because of their organic-inorganic hybrid molecular structure, polysiloxanes possess excellent adhesion to both inorganic and organic materials, making them highly promising for waterproofing and oil-repellent finishing of textiles.

[0004] To further improve the water and oil repellency of finishing agents, the "lotus effect" can be utilized to develop fluorine-free water and oil repellent agents with low surface energy and rough texture. By incorporating nanoparticles to construct hydrophobic nano-rough structures on the surface of solid materials, the design and control of superhydrophobic surface structures can be achieved. Among these, nano-SiO2 particles are widely used for water and oil repellency modification of fabrics due to their low toxicity, ease of surface functionalization, good thermal stability, and scalable production.

[0005] The surface of nano-SiO2 contains a large number of silanol groups. The siloxane bonds in polysiloxanes can react with these silanol groups upon heating, yielding modified nano-SiO2 particles with stable surface properties. Replacing the silanol groups with alkyl groups significantly reduces hydrophilicity and weakens particle-particle interactions. Furthermore, the properties of nano-SiO2 can be modulated by altering the functional groups of the silane coupling agent. For example, reacting SiO2 with a fluorinated silane coupling agent yields superhydrophobic materials; silane coupling agents with dye-terminated end groups can introduce metal coordination sites onto the nanoparticle surface. Tang Fangqiong et al. (authorization announcement number CN1300179C) used methacryloyl(3-trimethoxysilane)propyl ester as a coupling agent to modify the surface of nano-SiO2 microspheres, then added vinyl monomers for soap-free emulsion polymerization coating, obtaining a core / shell composite particle emulsion. However, the core / shell nano-SiO2 particle emulsion obtained by this method still has some problems that prevent it from being used as a fluorine-free waterproof and oil-repellent agent in fabric finishing. In this patent, propyl methacryloyl(3-trimethoxysilane) is used to block the hydrophilic silanol groups on the surface of nano-SiO2 particles. However, the polar acrylate groups in this silane coupling agent can partially counteract the hydrophobic effect of the silane group, resulting in poor hydrophobicity of the finished fabric when used as a waterproof and oil-repellent agent. Furthermore, using only propyl methacryloyl(3-trimethoxysilane) for surface modification of nano-SiO2 particles means that the modified nano-SiO2 particles have a large number of unsaturated double bonds on their surface. This leads to a rapid increase in particle volume, a decrease in specific surface area, and a reduction in surface charge density during the modification process through double bond addition polymerization. The balance between van der Waals forces and electrostatic repulsion is disrupted, making the particles more prone to aggregation and significantly affecting the emulsifying properties of the finishing agent. In addition, when the core / shell nano-SiO2 particle emulsion prepared in this patent is used as a waterproof and oil-repellent agent, the polymer film formed by cross-linking on the fiber surface cannot be firmly bonded to the fiber through chemical bonds, resulting in poor wash resistance of the finished fabric.

[0006] In summary, this invention addresses the aforementioned problems with existing SiO2 fluorine-free waterproof and oil-repellent agents. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a modified nano-SiO2 fluorine-free waterproof and oil-repellent finishing agent. This method has an easy-to-control preparation process. The waterproof and oil-repellent modified nano-SiO2 is chemically cross-linked and bonded to the fabric, which can give the finished fabric excellent waterproof and oil-repellent effects and water-washing resistance.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a modified nano-silica fluorine-free finishing agent, comprising the following components: S1. Mix nano-SiO2 with a silane coupling agent and graft it to obtain modified nano-SiO2. S2. The obtained modified nano-SiO2 is mixed with styrene compounds and benzoyl peroxide and subjected to an addition polymerization reaction to obtain PS-SCA-SiO2; S3. Mix PS-SCA-SiO2 with an emulsifier and emulsify to obtain a modified nano-silica fluorine-free finishing agent.

[0009] In step S1, the silane coupling agent is composed of a long-chain alkyl silane coupling agent and an unsaturated double-bond silane coupling agent in a molar ratio of 1:(1-10); preferably 1:(3-6). The molar ratio of the nano-SiO2 to the silane coupling agent is 1:(1-5).

[0010] The long-chain alkylsilane coupling agent is selected from C6-C6. 12 Long-chain silane coupling agents; preferably n-octyltriethoxysilane; The unsaturated double-bonded silane coupling agent is selected from vinyltrimethoxysilane.

[0011] In step S1, the grafting modification conditions are: temperature 80-150 ℃, time 1-5 h.

[0012] In step S2, the styrene compound is selected from one or more of styrene, 4-aminostyrene, 2-isopropenylphenylaniline, 2-methylstyrene, 4-methylstyrene, 4-methoxystyrene, and 2,5-dimethylstyrene; preferably 4-aminostyrene.

[0013] The molar ratio of the modified nano-SiO2 to the styrene compound and the benzoyl peroxide is 1:(0.5-10):(0.2-0.4).

[0014] In step S2, the conditions for the addition polymerization reaction are: temperature of 60-120 °C and time of 15-40 h.

[0015] In step S3, the emulsifier is selected from one or more of octadecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium chloride; The molar ratio of PS-SCA-SiO2 to emulsifier is 1:(0.5-2).

[0016] In step S3, the emulsification conditions are: room temperature and time of 60-120 min.

[0017] As a specific embodiment of the present invention, the method includes the following steps: (1) 10-50 g of nano-SiO2 was ultrasonically dispersed in 500 mL of toluene to prepare SiO2 solution, and then 10-50 g of silane coupling agent was added to prepare a mixed solution. The solution was mechanically stirred and refluxed at 80-150 °C for 1-5 h. Modified nano-SiO2 was obtained by centrifugation, washing and drying.

[0018] (2) Prepare a modified SiO2 solution by ultrasonically dispersing 5-25 g of modified nano-SiO2 in 500 mL of toluene, then add 2.5-20 mL of styrene compound and 0.1-2 mol of benzoyl peroxide, and react with mechanical stirring and reflux at 60-120 °C for 15-40 h. After centrifugation, washing and drying, obtain waterproof and oil-resistant modified nano-SiO2 (PS-SCA-SiO2).

[0019] (3) Disperse PS-SCA-SiO2 (10-40%, w / v) and 10-20 g / L hexadecyltrimethylammonium chloride in deionized water by ultrasonication, and emulsify for 60-120 min to obtain modified nano-SiO2 fluorine-free waterproof and oil-resistant finishing agent.

[0020] Secondly, the present invention provides a fluorine-free finishing agent for modified nano-silica prepared by the above method.

[0021] Thirdly, the present invention provides a fabric, which is obtained by treating with the modified nano-silica fluorine-free finishing agent as described in claim 9.

[0022] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) Nano-SiO2 is grafted and modified simultaneously by using silane coupling agents containing unsaturated double bonds and silane coupling agents with long alkane chains. While blocking the hydrophilic silanol groups, the silane coupling agents with long alkane chains enable the modified nano-SiO2 to have excellent waterproof performance, while the unsaturated double bond silane coupling agents can provide reaction sites.

[0023] The carbon chain length of silane coupling agents significantly affects their hydrolysis rate and interfacial activity. Within the range of 6 to 12 carbon atoms, increased carbon chain length increases steric hindrance, making it more difficult for water molecules to approach the silicon-oxygen bonds, thus gradually decreasing the hydrolysis rate of the silane coupling agent and affecting the modification efficiency of nano-SiO2. Simultaneously, increasing the carbon chain length gradually enhances the interfacial activity of the silane coupling agent, contributing to improved bonding strength and water resistance. Therefore, to balance the modification efficiency and hydrophobic properties of silane coupling agents for nano-SiO2, C8 n-octyltriethoxysilane is preferred as a long-chain alkane coupling agent.

[0024] Furthermore, during the mixing and compounding process of long-chain alkyl silane coupling agents and unsaturated double-bond silane coupling agents, if the proportion of long-chain alkyl silane coupling agents is too low, the hydrophobicity of the modified nano-SiO2 is significantly reduced, and the content of unsaturated double bonds on its surface is too high. This easily leads to double-bond addition polymerization reactions between the modified nano-SiO2 particles during the preparation process, causing a dramatic increase in the volume of the nanoparticles and affecting the emulsification performance of the fluorine-free waterproof and oil-repellent agent and the construction of the nano-rough structure on the surface of the finished fabric. When the proportion of long-chain alkyl silane coupling agents is too high, the hydrophobicity of the modified nano-SiO2 is significantly improved, but the content of unsaturated double bonds on its surface is too low, reducing the efficiency of the addition polymerization reaction between the modified nano-SiO2 and polystyrene-based substances. Since styrene-based compounds can provide oleophobicity, this ultimately affects the oleophobicity, crosslinking degree, and fastness of the polymer film. Therefore, to balance the hydrophobicity and oleophobicity of nano-SiO2, the preferred mixing ratio of long-chain alkyl silane coupling agents and unsaturated double-bond silane coupling agents is 1:(3-6).

[0025] (2) By utilizing the oleophobic properties of styrene compounds, the nano-SiO2 is modified to undergo an addition polymerization reaction with the unsaturated double bonds in the styrene compounds, thereby achieving the waterproof and oil-repellent modification of the nano-SiO2. At the same time, the 4-aminostyrene and the modified nano-SiO2 are connected by covalent bonds, which can effectively improve the interfacial bonding strength, reduce the excessively dense stacking of particles, and improve the accessibility of active sites.

[0026] (3) When using PS-SCA-SiO2 to waterproof and oil-proof textiles, the unsaturated double bonds in PS-SCA-SiO2 can continue to undergo addition polymerization during high-temperature baking, forming a polymer film through chemical cross-linking. At the same time, the structural stability of PS-SCA-SiO2 can be used to form a nano-rough structure on the fabric surface, and the "lotus effect" can be used to further improve the waterproof and oil-proof effect of the treated fabric.

[0027] (4) The styrene compounds in PS-SCA-SiO2 contain amino groups. The positively charged amino groups can form valence bonds with the negatively charged groups on the fiber. Furthermore, the long alkane chains in PS-SCA-SiO2 give it good film-forming properties. During fabric finishing, it can be firmly fixed on the fiber surface, improving the stability of the overall particle stacking structure on the fabric surface and further enhancing the water resistance and oil resistance of the finished fabric. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation process of PS-SCA-SiO2 provided by the present invention.

[0029] Figure 2 This is a schematic diagram of the chemical crosslinking and valence bonding of PS-SCA-SiO2 on fibers provided by the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0032] Unless otherwise specified, all reagents, materials, instruments, etc. used in the following examples are commercially available.

[0033] Example 1 25 g of nano-SiO2 was ultrasonically dispersed in 500 mL of toluene to prepare a SiO2 solution. Then, a mixed solution of 25 g of vinyltrimethoxysilane and n-octyltriethoxysilane (molar ratio 1:5) was added. The mixture was mechanically stirred at 120 °C and refluxed for 3 h. Modified nano-SiO2 was obtained by centrifugation, washing, and drying.

[0034] 15 g of modified nano-SiO2 was ultrasonically dispersed in 500 mL of toluene to prepare a modified SiO2 solution. Then, 10 mL of 4-aminostyrene and 0.5 mol of benzoyl peroxide were added, and the mixture was mechanically stirred and refluxed at 70 °C for 30 h. The product was centrifuged, washed, and dried to obtain PS-SCA-SiO2.

[0035] PS-SCA-SiO2 (10%, w / v) and 15 g / L hexadecyltrimethylammonium chloride were ultrasonically dispersed in deionized water and emulsified for 80 min to obtain a modified nano-SiO2 fluorine-free waterproof and oil-resistant finishing agent.

[0036] Comparative Example 1 Same as Example 1, except that 25 g of vinyltrimethoxysilane was used in the preparation of PS-SCA-SiO2. Other preparation methods are the same as in Example 1.

[0037] Comparative Example 2 Same as Example 1, except that 25 g of n-octyltriethoxysilane was used in the preparation of PS-SCA-SiO2. Other preparation methods are the same as in Example 1.

[0038] Comparative Example 3 Same as Example 1, except that in the preparation of PS-SCA-SiO2, a mixed solution of 25 g of vinyltrimethoxysilane and n-hexyltriethoxysilane (mixing ratio of 1:5) was used. Other preparation methods are the same as in Example 1.

[0039] Comparative Example 4 Same as Example 1, except that in the preparation of PS-SCA-SiO2, a mixed solution of 25 g of vinyltrimethoxysilane and n-dodecyltriethoxysilane (combination ratio of 1:5) was used. Other preparation methods are the same as in Example 1.

[0040] Example 2 A SiO2 solution was prepared by ultrasonically dispersing 25 g of nano-SiO2 in 500 mL of toluene. Then, a mixed solution of 25 g of vinyltrimethoxysilane and n-octyltriethoxysilane (1:5 ratio) was added. The mixture was mechanically stirred and refluxed at 120 °C for 3 h. After centrifugation, washing, and drying, modified nano-SiO2 was obtained. A modified SiO2 solution was also prepared by ultrasonically dispersing 15 g of modified nano-SiO2 in 500 mL of toluene. Then, 10 mL of 4-aminostyrene and 0.5 mol of benzoyl peroxide were added. The mixture was mechanically stirred and refluxed at 70 °C for 30 h. After centrifugation, washing, and drying, PS-SCA-SiO2 was obtained. PS-SCA-SiO2 (10%, w / v) and 15 g / L hexadecyltrimethylammonium chloride were ultrasonically dispersed in deionized water and emulsified for 80 min to obtain a fluorine-free, water- and oil-repellent modified nano-SiO2 finishing agent.

[0041] Comparative Example 5 Same as Example 2, except that 10 mL of styrene was used in the preparation of PS-SCA-SiO2. Other preparation methods are the same as in Example 2.

[0042] Comparative Example 6 Same as Example 2, except that 0.5 mL of 4-aminostyrene was used in the preparation of PS-SCA-SiO2. Other preparation methods are the same as in Example 2.

[0043] Comparative Example 7 Same as Example 2, except that 30 mL of 4-aminostyrene was used in the preparation of PS-SCA-SiO2. Other preparation methods are the same as in Example 2.

[0044] Example 3 A SiO2 solution was prepared by ultrasonically dispersing 25 g of nano-SiO2 in 500 mL of toluene. Then, a mixed solution of 25 g of vinyltrimethoxysilane and n-octyltriethoxysilane (1:5 ratio) was added. The mixture was mechanically stirred and refluxed at 120 °C for 3 h. After centrifugation, washing, and drying, modified nano-SiO2 was obtained. A modified SiO2 solution was also prepared by ultrasonically dispersing 15 g of modified nano-SiO2 in 500 mL of toluene. Then, 10 mL of 4-aminostyrene and 0.5 mol of benzoyl peroxide were added. The mixture was mechanically stirred and refluxed at 70 °C for 30 h. After centrifugation, washing, and drying, PS-SCA-SiO2 was obtained. PS-SCA-SiO2 (25%, w / v) and 15 g / L hexadecyltrimethylammonium chloride were ultrasonically dispersed in deionized water and emulsified for 80 min to obtain a fluorine-free, water- and oil-repellent modified nano-SiO2 finishing agent.

[0045] Comparative Example 8 Same as Example 3, except that in the preparation of the fluorine-free waterproof and oil-repellent finishing agent, PS-SCA-SiO2 (5%, w / v) was ultrasonically dispersed in deionized water. Other preparation methods are the same as in Example 3.

[0046] Comparative Example 9 Same as Example 3, except that in the preparation of the fluorine-free waterproof and oil-repellent finishing agent, PS-SCA-SiO2 (60%, w / v) was ultrasonically dispersed in deionized water. Other preparation methods are the same as in Example 3.

[0047] The finishing agents prepared in Comparative Examples 1-9 and Examples 1-3 were fixed onto pure cotton woven fabrics using the pad-baking method. The water repellency, oil repellency, and water resistance of the finished cotton fabrics were tested to evaluate the water and oil repellency of the finishing agents. The washing method was carried out according to the provisions of GB / T 8629-2017 "Test Procedures for Household Washing and Drying of Textiles". The water repellency effect was carried out according to the provisions of GB / T4745-2012 "Test and Evaluation of Water Repellency of Textiles - Water Repellency Method"; the oil repellency effect was carried out according to the provisions of GB / T19977-2014 "Test for Oil Repellency and Hydrocarbon Resistance of Textiles". The finishing process of the pad-baking method is as follows: the cotton fabric is dipped and rubbed twice in 60 g / L finishing agent, the pad-up rate is controlled at 60%, pre-dried at 80℃ for 2 min, and then baked at 160℃ for 2 min to obtain the finished cotton fabric.

[0048] (1) The effect of silane coupling agent on the waterproof and oil-repellent properties of finishing agent The effects of the finishing agents prepared in Comparative Examples 1-4 and Example 1 on the water repellency and oil repellency of cotton fabrics were tested, and the results are shown in Table 1.

[0049] Table 1. Effects of silane coupling agents on the water repellency, washability, and oil repellency of cotton fabrics.

[0050] As shown in Table 1, the finishing agent prepared in Example 1 exhibits superior water repellency and washability compared to the finishing agents prepared in Comparative Examples 1-4. This is because the modified nano-SiO2 in Comparative Example 1 lacked a hydrophobic long-chain silane coupling agent, significantly reducing its hydrophobicity and resulting in an excessively high content of unsaturated double bonds on its surface. During the preparation process, double bond addition polymerization occurred between the modified nano-SiO2 particles, leading to a significant increase in nanoparticle size and affecting the emulsifying properties of the finishing agent and the construction of the nano-rough structure on the surface of the finished fabric. Consequently, its water repellency, washability, and oil resistance were poor. In Comparative Example 2, the modified nano-SiO2 lacked a silane coupling agent with unsaturated double bonds, improving its hydrophobicity. However, the absence of unsaturated double bonds on its surface prevented in-situ polymerization to form poly(4-aminostyrene) with oil-resistant properties. Because positively charged amino groups can form valence bonds with negatively charged groups on fibers, improving the water resistance of polymer films, they have poor water repellency, water resistance, and oil resistance.

[0051] Compared to Example 1, the long-chain alkane coupling agent used in Comparative Example 3 has a shorter carbon chain, resulting in lower hydrophobicity and interfacial activity, thus reducing the water-repellent properties and washability of the finishing agent. The long-chain alkane coupling agent used in Comparative Example 4 has an even longer carbon chain, exhibiting higher hydrophobicity and interfacial activity than Example 1. However, the increased carbon chain length leads to greater steric hindrance, making it more difficult for water molecules to approach the silicon-oxygen bonds. This gradually reduces the hydrolysis rate of the silane coupling agent, affecting the modification efficiency of nano-SiO2 and resulting in incomplete sealing of the hydrophilic silanol groups on the surface of nano-SiO2, further reducing its hydrophobic properties. Therefore, the water-repellent properties and washability of Comparative Example 4 are worse than those of Example 1, but its washability is slightly better than that of Comparative Example 3.

[0052] (2) The effect of cationic groups on the water and oil repellency of finishing agents Cationic groups are an important factor affecting the water and oil repellency of finishing agents. The test results of the water repellency, oil repellency, and water resistance of the finishing agents prepared in Comparative Example 5 and Example 2 are shown in Table 2.

[0053] Table 2. Effects of cationic groups on the water repellency, oil repellency, and wash resistance of cotton fabrics.

[0054] As shown in Table 2, the finishing agent prepared in Example 2 exhibits significantly better wash resistance than the finishing agent prepared in Comparative Example 5. This is because Comparative Example 5 uses styrene without cationic groups for polymerization, preventing the formation of valence bonds between PS-SCA-SiO2 and the negatively charged groups of the fibers during fabric finishing. Consequently, the polymer film exhibits poor adhesion to the fibers. Furthermore, due to the oleophobic nature of amino groups, Example 2 demonstrates superior oil-repellent properties compared to Comparative Example 5.

[0055] The amino content in the finishing agent is also an important factor affecting its waterproof and oil-repellent properties. The test results of the water repellency, oil repellency, and water resistance of the finishing agents prepared in Comparative Examples 6-7 are shown in Table 3.

[0056] Table 3. Effects of 4-aminostyrene addition on the water repellency, oil repellency, and wash resistance of cotton fabrics.

[0057] As shown in Table 3, compared with Example 2, the oleophobicity and washability of the prepared finishing agent were significantly reduced when the amino content decreased. This is because amino groups have hydrophilic and oleophobic properties. When the amino content is low, the water repellency of the polymer film is not significantly affected, but its oleophobicity is significantly reduced. Simultaneously, the reduction in the amino content in the polymer film significantly affects the valence bond between the amino group and the negatively charged groups of the fiber, thus greatly reducing the washability. Conversely, when the amino content increases, the oleophobicity of the polymer film is not significantly affected, but the hydrophilic amino group significantly reduces its water repellency.

[0058] (3) Effect of PS-SCA-SiO2 dosage on the waterproof and oil-repellent properties of the finishing agent The effects of the finishing agents prepared in Comparative Examples 8-9 and Example 3 on the water repellency and oil repellency of cotton fabrics were tested, and the results are shown in Table 4.

[0059] Table 4. Effects of PS-SCA-SiO2 dosage on the water repellency, oil repellency, and water resistance of cotton fabrics.

[0060] As shown in Table 4, the water repellency, oil repellency, and washability of Example 3 are superior to those of Comparative Examples 8-9. This is because when the PS-SCA-SiO2 content in the finishing agent increases, the nanoparticles inside the polymer film formed by chemical cross-linking on the cotton fiber surface are more tightly arranged and the film density is greater. The "lotus effect" generated by the nano-rough structure on the fiber surface is more significant. Therefore, the finishing agent prepared in Example 3 has better water and oil repellency than that in Comparative Example 8. When the PS-SCA-SiO2 content in the finishing agent is too high, the finishing agent is difficult to emulsify, the viscosity increases, and its fluidity decreases, making it difficult to apply the finishing agent to the fabric. This significantly reduces the water repellency, oil repellency, and washability of the finished fabric.

[0061] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a modified nano-silica fluorine-free finishing agent, characterized in that, It includes the following components: S1. Mix nano-SiO2 with a silane coupling agent and graft it to obtain modified nano-SiO2. S2. The obtained modified nano-SiO2 is mixed with styrene compounds and benzoyl peroxide and subjected to an addition polymerization reaction to obtain PS-SCA-SiO2; S3. Mix PS-SCA-SiO2 with an emulsifier and emulsify to obtain a modified nano-silica fluorine-free finishing agent.

2. The method according to claim 1, characterized in that, In step S1, the silane coupling agent is composed of a long-chain alkyl silane coupling agent and an unsaturated double-bond silane coupling agent in a molar ratio of 1:(1-10); The molar ratio of the nano-SiO2 to the silane coupling agent is 1:(1-5).

3. The method according to claim 2, characterized in that, The long-chain alkylsilane coupling agent is selected from C6-C6. 12 Long-chain silane coupling agents; The unsaturated double-bonded silane coupling agent is selected from vinyltrimethoxysilane.

4. The method according to claim 1, characterized in that, In step S1, the grafting modification conditions are: temperature 80-150 ℃, time 1-5 h.

5. The method according to claim 1, characterized in that, In step S2, the styrene compound is selected from one or more of styrene, 4-aminostyrene, 2-isopropenylphenylaniline, 2-methylstyrene, 4-methylstyrene, 4-methoxystyrene, and 2,5-dimethylstyrene; The molar ratio of the modified nano-SiO2 to the styrene compound and the benzoyl peroxide is 1:(0.5-10):(0.2-0.4).

6. The method according to claim 1, characterized in that, In step S2, the conditions for the addition polymerization reaction are: temperature of 60-120 °C and time of 15-40 h.

7. The method according to claim 1, characterized in that, In step S3, the emulsifier is selected from one or more of octadecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, and dodecyltrimethylammonium chloride; The molar ratio of PS-SCA-SiO2 to emulsifier is 1:(0.5-2).

8. The method according to claim 1, characterized in that, In step S3, the emulsification conditions are: room temperature and time of 60-120 min.

9. The modified nano-silica fluorine-free finishing agent prepared by the method of any one of claims 1-8.

10. A fabric, characterized in that, The fabric is obtained by treating it with the modified nano-silica fluorine-free finishing agent as described in claim 9.

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