Anti-pilling agent and preparation method thereof

Abstract

The invention discloses an anti-pilling agent and a preparation method thereof, and belongs to the technical field of textile assistants. The method comprises the steps of raw material preparation, nano silicon dioxide modification, emulsion polymerization and compounding treatment, specifically, nano silicon dioxide is modified through a silane coupling agent, the modified nano silicon dioxide and acrylate monomer emulsion are polymerized to form a SiO-acrylate covalent hybrid network, then the SiO-acrylate covalent hybrid network is compounded with chitosan quaternary ammonium salt and an organic zirconium cross-linking agent, and a solid product is obtained through spray drying. Chemical bonding replaces traditional physical winding, the problem that washing fastness and hand feeling of an existing auxiliary are difficult to consider is solved, and meanwhile the good anti-pilling effect is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of textile auxiliaries, in particular to an anti-pilling agent and a preparation method thereof. BACKGROUND

[0002] In the field of textile industry, the problem of fabric pilling has always been a key difficulty affecting the quality and use performance of textiles. The pilling phenomenon will make the surface of the fabric rough and lose luster, and in severe cases, it will also affect the functional properties of the fabric such as warmth retention and air permeability, and reduce the wearing experience of consumers. At present, the commonly used anti-pilling agents on the market mainly include silicone, acrylate, polyurethane and the like. However, these traditional anti-pilling agents have many shortcomings. For example, although silicone anti-pilling agents have good softness and anti-pilling effect, they have poor wash resistance, and the effect decreases significantly after multiple washes; acrylate anti-pilling agents have good stability, but the film formed is relatively hard, which will affect the hand feeling and comfort of the fabric to some extent; polyurethane anti-pilling agents have good comprehensive performance, but the preparation cost is relatively high, and some products have environmental problems. In addition, the existing anti-pilling agents often have poor compatibility when used in a bath with other textile auxiliaries, resulting in complex finishing process and increased production cost. Therefore, it has become a technical problem to be solved in the field to develop an anti-pilling agent with good wash resistance, without affecting the hand feeling of the fabric, and with good anti-pilling effect, and a preparation method thereof. SUMMARY

[0003] In view of the shortcomings of the prior art described above, the purpose of the present application is to provide an anti-pilling agent and a preparation method thereof, aiming to solve the technical problems of the anti-pilling agents in the prior art, which have general wash resistance and anti-pilling effect and affect the hand feeling of the fabric.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: A preparation method of an anti-pilling agent, characterized in that it comprises the following steps: (1) Raw material preparation: weigh 10-20 parts of nano-silicon dioxide, 2-4 parts of silane coupling agent, 50-70 parts of deionized water, 15-25 parts of butyl acrylate, 5-10 parts of methyl methacrylate, 3-6 parts of hydroxyethyl acrylate, 0.1-0.3 parts of potassium persulfate, 1-3 parts of chitosan quaternary ammonium salt, 0.5-1.5 parts of organic zirconium crosslinking agent and 0.1-0.3 parts of citric acid; (2) Modification of nano-silicon dioxide: disperse the nano-silicon dioxide in deionized water, add the silane coupling agent, and stir at 60-80℃ and pH 8-10 for 2-3 hours to obtain modified nano-silicon dioxide with surface grafted active groups, and control the average particle size to be 80-120nm; (3) Emulsion polymerization: modified nano-silica is mixed with butyl acrylate, methyl methacrylate and hydroxyethyl acrylate, and potassium persulfate initiator is added to carry out emulsion polymerization reaction at 75°C for 3.5 hours to prepare a copolymer emulsion; (4) Compound treatment: chitosan quaternary ammonium salt is added to the copolymer emulsion, and after stirring uniformly, organic zirconium crosslinking agent is added, the pH of the system is adjusted to 6.0±1.0 with citric acid, and stirring is carried out at 25-30°C for 15-20 minutes to prepare an anti-pilling agent emulsion, and after spray drying, a solid product is obtained.

[0005] Further, in the preparation method of the anti-pilling agent, the silane coupling agent in step (1) is γ-glycidoxypropyltrimethoxysilane, and the weight ratio of nano-silica to silane coupling agent is 5:1.

[0006] Further, in the preparation method of the anti-pilling agent, the degree of substitution of the chitosan quaternary ammonium salt in step (1) is 0.3-0.5.

[0007] Further, in the preparation method of the anti-pilling agent, in step (2), when the nano-silica is dispersed in deionized water, ultrasonic dispersion treatment is adopted, the ultrasonic frequency is 40-60 kHz, and the ultrasonic time is 10-20 minutes.

[0008] Further, in the preparation method of the anti-pilling agent, in step (2), the pH value of the reaction system is adjusted to 8-10 by adding sodium hydroxide solution.

[0009] Further, in the preparation method of the anti-pilling agent, in step (3), the emulsion polymerization reaction is carried out under nitrogen protection and at a stirring speed of 300-400 rpm.

[0010] Further, in the preparation method of the anti-pilling agent, in step (3), the solid content of the copolymer emulsion is 30-40%.

[0011] Further, in the preparation method of the anti-pilling agent, in step (4), when the pH of the system is adjusted to 6.0±1.0, 0.1 mol / L citric acid aqueous solution is added dropwise, and a pH meter with a precision of ±0.01 is used for real-time monitoring.

[0012] Further, in the preparation method of the anti-pilling agent, in step (4), the anti-pilling agent emulsion prepared is subjected to spray drying treatment, the inlet air temperature is 180-200°C, the outlet air temperature is 80-90°C, and after drying, the product is crushed through an 80-mesh sieve to obtain a solid product with uniform particle size.

[0013] Correspondingly, the present application also provides an anti-pilling agent, which is different from the prior art in that it is prepared by the preparation method of the anti-pilling agent described above.

[0014] Beneficial effects: The present invention provides an anti-pilling agent and a preparation method thereof, which have at least the following advantages compared to the prior art: (1) Excellent anti-pilling performance and outstanding washability. The SiO2-acrylate covalent hybrid network formed by silane coupling agent-modified nano-silica and acrylate monomers replaces the traditional physical entanglement with chemical bonding, significantly improving the anti-pilling effect. At the same time, the three-dimensional structure formed by the covalent network and organic zirconium cross-linking can effectively resist the mechanical friction and chemical effects of 50 water washes, and the grade remains above grade 3 after washing, solving the pain point of poor washability of traditional silicone additives.

[0015] (2) Taking into account both fabric feel and functionality. The introduction of chitosan quaternary ammonium salt can adjust the rigidity of the acrylate film. The flexibility of its molecular chain forms a balance with the nano-silica inorganic skeleton, which improves the feel of the finished fabric and avoids the stiff feel problem caused by traditional acrylate additives. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 These are actual photos of the samples after anti-pilling performance testing, showing the central area of ​​each sample.

[0017] Figure 2 These are actual photos of the samples after the washability test, showing the central area of ​​each sample. DETAILED DESCRIPTION

[0018] To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The "system" mentioned herein refers to the reaction mixture system involved in the step in which the word appears.

[0020] A method for preparing an anti-pilling agent comprises the following steps: (1) Raw material preparation: weigh 10-20 parts of nano-silica, 2-4 parts of silane coupling agent, 50-70 parts of deionized water, 15-25 parts of butyl acrylate, 5-10 parts of methyl methacrylate, 3-6 parts of hydroxyethyl acrylate, 0.1-0.3 parts of potassium persulfate, 1-3 parts of chitosan quaternary ammonium salt, 0.5-1.5 parts of organic zirconium crosslinking agent, and 0.1-0.3 parts of citric acid; (2) Nano-silica modification: disperse nano-silica in deionized water, add silane coupling agent, and stir at 60-80°C and pH 8-10 for 2-3 hours to obtain modified nano-silica with active groups grafted on the surface, and control the average particle size to be 80-120 nm; (3) Emulsion polymerization: mix the modified nano-silica with butyl acrylate, methyl methacrylate, and hydroxyethyl acrylate, add potassium persulfate initiator, and perform emulsion polymerization at 75°C for 3.5 hours to obtain a copolymer emulsion; (4) Compound treatment: add chitosan quaternary ammonium salt to the copolymer emulsion, stir uniformly, add organic zirconium crosslinking agent, adjust the pH of the system to 6.0±1.0 with citric acid, and stir at 25-30°C for 15-20 minutes to obtain an anti-pilling agent emulsion. After spray drying, the solid product is obtained, which is the anti-pilling agent.

[0021] The traditional organosilicon or acrylate relies on intermolecular physical entanglement, and the wash resistance depends on the increase of molecular weight, but it will cause the hand feeling to become hard. Compared with the prior art, the most core innovation of the present application is to modify nano-silica with silane coupling agent (γ-glycidyloxypropyltrimethoxysilane) to graft epoxy groups on the surface of nano-silica. This process can introduce active sites on the surface of nanoparticles, laying a foundation for subsequent chemical reaction with acrylate monomers. The epoxy groups on the surface of modified nano-silica undergo ring-opening reaction with the hydroxyl groups in hydroxyethyl acrylate under alkaline conditions to form ether bonds (-O-), and at the same time, the acrylate monomers form a main chain through free radical polymerization, finally constructing a SiO2-polyacrylate covalent hybrid network. Compared with traditional physical entanglement, chemical bonding can significantly improve wash resistance, and the inorganic skeleton of nano-silica can enhance the film strength, solving the technical contradiction of traditional materials that "wash resistance improvement must sacrifice hand feeling".

[0022] Furthermore, the silane coupling agent in step (1) is γ-glycidyloxypropyltrimethoxysilane, and the weight ratio of nano-silica to silane coupling agent is 5:1. The molecular structure of γ-glycidyloxypropyltrimethoxysilane contains both epoxy groups (reactive functional groups) and trimethoxysilyl groups (hydrolyzable groups). Among them, the trimethoxysilyl group can be hydrolyzed in aqueous solution to form silanol groups, which can undergo condensation reaction with the hydroxyl groups on the surface of nano-silica to achieve chemical modification of nano-silica and graft stable organic functional groups on its surface. The epoxy group has high reactivity and can react chemically with acrylate monomers in the subsequent emulsion polymerization stage to form stable covalent bonds, providing key chemical bonding sites for constructing the SiO2-acrylate covalent hybrid network. This is the core foundation for realizing the innovative "covalent hybrid" structure. Compared with ordinary silane coupling agents, it can better ensure the stability of the hybrid system. Furthermore, a 5:1 ratio ensures that the silane coupling agent is evenly grafted onto the nano-silica surface (forming an ideal particle size of 80-120 nm) while providing ample reaction sites for subsequent emulsion polymerization with acrylate monomers. This ultimately achieves a highly efficient bond between the inorganic framework (nano-silica) and the organic polymer (acrylate), balancing film strength and washability. It should be noted that if the silane coupling agent ratio is too high, it will over-coat the nano-silica surface, potentially blocking some active sites and affecting the reaction with the acrylate monomer. If the ratio is too low, the nano-silica surface will not be adequately covered, making it difficult to form sufficient active groups, resulting in an incomplete hybrid network.

[0023] Furthermore, the degree of substitution of the chitosan quaternary ammonium salt in step (1) is 0.3-0.5. The degree of substitution of the chitosan quaternary ammonium salt directly affects its water solubility and charge characteristics. When the degree of substitution is 0.3-0.5, it can not only ensure its good dispersibility in the copolymer emulsion, but also avoid agglomeration with other components (such as modified nano-silica and acrylate polymer) due to excessive charge, thereby ensuring the stability of the compounding process. Within this degree of substitution range, the cationic groups in the chitosan quaternary ammonium salt molecules can form weak interactions with hydroxyl groups, carboxyl groups, etc. on the surface of the fabric fibers, thereby assisting in enhancing the adhesion of the anti-pilling agent on the fabric surface. At the same time, the flexibility of its molecular chain can adjust the rigidity of the acrylate film, preventing the fabric from becoming hard, and taking into account both functionality and comfort.

[0024] Further, in step (2), the nanosilica is dispersed in deionized water by ultrasonic dispersion treatment, the ultrasonic frequency is 40-60 kHz, and the ultrasonic time is 10-20 minutes, so as to ensure uniform dispersion of the nanosilica in the deionized water. Due to the small particle size and high surface energy of the nanosilica, it is prone to agglomeration. Ultrasonic dispersion utilizes the mechanical shear force and cavitation effect generated by high-frequency vibration of 40-60 kHz to effectively break the agglomerates of nanosilica, so that a stable and uniform dispersion system of nanosilica in deionized water is formed. This frequency range can provide sufficient dispersion energy, and the structure of the nanoparticles will not be damaged due to excessively high frequency; the ultrasonic time of 10-20 minutes ensures sufficient dispersion, which lays a uniform micro foundation for subsequent reaction with the silane coupling agent.

[0025] Further, in step (2), the pH value of the reaction system is adjusted to 8-10 by adding sodium hydroxide solution, and the pH value is continuously monitored during the reaction and sodium hydroxide is supplemented in time to maintain the alkalinity of the system. In this application, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane, and its hydrolysis and condensation reaction needs to be carried out efficiently under alkaline conditions (pH 8-10). The alkaline environment can promote the hydrolysis of trimethoxyl groups in the silane coupling agent molecules to generate more silicon hydroxyl groups (-Si-OH), which then undergo condensation reaction with the hydroxyl groups on the surface of nanosilica to realize the grafting of active groups on the surface of nanosilica. Under the alkaline conditions of pH 8-10, the hydroxyl groups (-Si-OH) on the surface of nanosilica will partially dissociate, making the particle surface negatively charged, and reducing agglomeration through electrostatic repulsion. Continuous monitoring and timely supplement of sodium hydroxide can avoid fluctuations in pH value caused by possible acidic by-products during the reaction. Stable alkaline environment can ensure uniform reaction rate and consistent modification degree, ensuring stable performance of modified nanosilica prepared in each batch, and providing uniform raw material basis for subsequent emulsion polymerization and compounding treatment.

[0026] Further, in step (3), the emulsion polymerization reaction is carried out under nitrogen protection and at a stirring speed of 300-400 rpm. Nitrogen, as an inert gas, can isolate the reaction system from oxygen in the air. Nitrogen protection can ensure efficient decomposition of the initiator to generate free radicals, ensure sufficient copolymerization of monomers such as butyl acrylate, methyl methacrylate, and hydroxyethyl acrylate with modified nanosilica, improve the polymerization conversion rate and stability of the copolymerization emulsion, and avoid fluctuations in product performance caused by oxygen interference. Low stirring speed can cause material stratification and incomplete reaction; high stirring speed may damage the colloidal stability of the emulsion, causing demulsification or particle agglomeration. A stirring speed of 300-400 rpm can ensure uniform dispersion of modified nanosilica, monomers, and initiators in the reaction system, avoid uneven polymerization caused by excessively high local concentration (such as the formation of coarse particles due to rapid local monomer polymerization), and ensure uniform particle size distribution of the copolymerization emulsion.

[0027] Further, the solid content of the copolymer emulsion in step (3) is 30-40%. A solid content of 30-40% is the key to balancing the stability of the emulsion system. If the solid content is too low, the water content is too high, which will result in insufficient concentration of active ingredients during subsequent compounding and processing, and more additives need to be adjusted, which may increase the risk of system stratification or agglomeration. If the solid content is too high, the viscosity of the emulsion will increase significantly, resulting in poor flowability, making it difficult to mix with subsequent added chitosan quaternary ammonium salt, organic zirconium crosslinking agent, etc., affecting the smooth progress of the compounding process.

[0028] It should be noted that in actual operation, if one-time feeding is used in step (3), the reaction may be out of control, therefore, it is preferred to use the "monomer dropwise" method to gradually add the monomers into the initiator system in proportion, control the monomer concentration to maintain a stable polymerization rate, and ensure uniform latex particle size. Specifically, the modified nano-silica dispersion liquid is heated to 75°C, and under nitrogen protection and 300-400 rpm stirring, the mixed monomers of butyl acrylate, methyl methacrylate and hydroxyethyl acrylate are added into the system at a uniform speed (dropped within 2 hours), and a 5% potassium persulfate initiator solution is prepared and added synchronously with the monomers (delayed for 10 minutes), after the addition is completed, continue to react for 1.5 hours, and the total reaction time is 3.5 hours.

[0029] In addition, before emulsion polymerization in step (3), 0.05-0.1 parts of triethylamine (epoxy ring opening catalyst) can be added to the modified nano-silica dispersion liquid to promote the reaction of the epoxy group with the hydroxyl group of hydroxyethyl acrylate and ensure the covalent bonding efficiency.

[0030] Further, in step (4), when the pH of the system is adjusted to 6.0±1.0, 0.1 mol / L citric acid aqueous solution is added dropwise, and a pH meter with an accuracy of ±0.01 is used for real-time monitoring to ensure that there is no turbidity in the system during the adjustment process. Adjusting the pH of the system to 6.0±1.0 (weakly acidic range) is a key condition for subsequent reactions: this pH environment can promote effective crosslinking between the organic zirconium crosslinking agent and the hydroxyl groups (such as the hydroxyethyl acrylate group) in the copolymer emulsion and the amino group of the chitosan quaternary ammonium salt, forming a stable three-dimensional network structure. If the pH deviates from this range, excessive acidity (pH<5) may cause the zirconium crosslinking agent to hydrolyze prematurely and lose effectiveness, and excessive alkalinity (pH>7) may cause the chitosan quaternary ammonium salt to precipitate or the copolymer emulsion to break, both of which will damage the crosslinking effect of the system. Real-time monitoring with a pH meter with an accuracy of ±0.01 can ensure that the pH value is strictly controlled within the target range, providing a stable environment for the synergistic reaction between components.

[0031] Further, the anti-pilling agent emulsion prepared in step (4) is subjected to spray drying treatment, the inlet air temperature is 180-200℃, the outlet air temperature is 80-90℃, and after drying, the product is crushed through an 80-mesh sieve to obtain a solid product with uniform particle size. The inlet air temperature for spray drying is 180-200℃, which can quickly evaporate the moisture in the anti-pilling agent, avoiding decomposition or denaturation of the effective components (such as the network structure formed by chitosan quaternary ammonium salt and organic zirconium crosslinking agent) caused by long-term high temperature; and the outlet air temperature is controlled at 80-90℃, which can ensure that the water content of the dried product is appropriate (too low water content can easily cause dust flying, and too high water content can cause caking), and at the same time, avoid the influence of residual moisture on the storage stability of the product. This temperature range can maximize the retention of the chemical activity and functional structure of the anti-pilling agent while achieving efficient drying. Crushing the dried product through an 80-mesh sieve can control the particle size of the solid product within a uniform range (below 180μm). Uniform particle size distribution can ensure more uniform dispersion of the product in subsequent applications (such as when preparing a working solution), avoid uneven dissolution or dispersion caused by differences in particle size, and thus ensure consistency in the amount and stability of the effect when finishing the fabric surface, reducing the differences in hand feeling or anti-pilling effect caused by local overuse or insufficient use.

[0032] In actual application, before adding chitosan quaternary ammonium salt to the copolymer emulsion in step (4), 0.3-0.5 parts of a non-ionic emulsifier can be added to adjust the charge of the emulsion, and after stirring for 5 minutes, the chitosan quaternary ammonium salt is added, thereby solving the potential risk of charge conflict.

[0033] The present application also correspondingly provides an anti-pilling agent, which is prepared by the preparation method of the anti-pilling agent described above, which is different from the prior art.

[0034] For the sake of convenience, the following examples are further described. In order to save space, only the raw material components and key parameters are listed in each example, and repeated descriptions are omitted.

[0035] Example 1 The raw materials in step (1) (parts by weight) 15 parts of nano-silica, 3 parts of γ-glycidoxypropyltrimethoxysilane, 60 parts of deionized water, 20 parts of butyl acrylate, 7.5 parts of methyl methacrylate, 4.5 parts of hydroxyethyl acrylate, 0.2 parts of potassium persulfate, 2 parts of chitosan quaternary ammonium salt (degree of substitution 0.4), 1.0 parts of organic zirconium crosslinking agent, and 0.2 parts of citric acid.

[0036] Key parameters of steps (2) to (4) Step (2): ultrasonic frequency 50kHz, 15 minutes; reaction temperature 70℃, pH 9, reaction time 2.5 hours, modified nano-silica particle size 100nm.

[0037] Step (3): nitrogen protection, stirring speed 350 rpm, 75 °C reaction for 3.5 hours, the solid content of the copolymer emulsion is 35%.

[0038] Step (4): 0.1 mol / L citric acid to adjust pH 6.0, stirring at 27 °C for 18 minutes; spray drying, inlet temperature 190 °C, outlet temperature 85 °C, and passing through an 80-mesh sieve.

[0039] Example 2 Raw materials in step (1) (weight parts) Nano-silica 10 parts, γ-glycidoxypropyltrimethoxysilane 2 parts, deionized water 50 parts, butyl acrylate 15 parts, methyl methacrylate 5 parts, hydroxyethyl acrylate 3 parts, potassium persulfate 0.1 part, chitosan quaternary ammonium salt 1 part (degree of substitution 0.3), organic zirconium crosslinking agent 0.5 part, and citric acid 0.1 part.

[0040] Key parameters of steps (2) to (4) Step (2): ultrasonic 40 kHz, 10 minutes; reaction temperature 60 °C, pH 8, reaction time 2 hours, and the particle size of the modified nano-silica is 80 nm.

[0041] Step (3): nitrogen protection, stirring speed 300 rpm, 75 °C reaction for 3.5 hours, the solid content of the copolymer emulsion is 30%.

[0042] Step (4): 0.1 mol / L citric acid to adjust pH 5.5, stirring at 25 °C for 15 minutes; spray drying, inlet temperature 180 °C, outlet temperature 80 °C, and passing through an 80-mesh sieve.

[0043] Example 3 Raw materials in step (1) (weight parts) Nano-silica 20 parts, γ-glycidoxypropyltrimethoxysilane 4 parts, deionized water 70 parts, butyl acrylate 25 parts, methyl methacrylate 10 parts, hydroxyethyl acrylate 6 parts, potassium persulfate 0.3 part, chitosan quaternary ammonium salt 3 parts (degree of substitution 0.5), organic zirconium crosslinking agent 1.5 parts, and citric acid 0.3 part.

[0044] Key parameters of steps (2) to (4) Step (2): ultrasonic 60 kHz, 20 minutes; reaction temperature 80 °C, pH 10, reaction time 3 hours, and the particle size of the modified nano-silica is 120 nm.

[0045] Step (3): nitrogen protection, stirring speed 400 rpm, 75 °C reaction for 3.5 hours, the solid content of the copolymer emulsion is 40%.

[0046] Step (4): 0.1 mol / L citric acid to adjust pH 6.5, 30℃ stirring for 20 minutes; spray drying inlet 200℃, outlet 90℃, 80 mesh screen.

[0047] Example 4 Raw materials in step (1) (weight parts) Nano-silica 15 parts, γ-glycidoxypropyltrimethoxysilane 3 parts, deionized water 60 parts, butyl acrylate 20 parts, methyl methacrylate 7.5 parts, hydroxyethyl acrylate 4.5 parts, potassium persulfate 0.2 parts, chitosan quaternary ammonium salt 2 parts (degree of substitution 0.3), organic zirconium crosslinking agent 1.0 parts, citric acid 0.2 parts.

[0048] Key parameters of steps (2) to (4) Step (2): ultrasonic 50 kHz, 15 minutes; reaction temperature 70℃, pH 8.5, reaction time 2.5 hours, modified nano-silica particle size 90 nm.

[0049] Step (3): nitrogen protection, stirring speed 350 rpm, 75℃ reaction for 3.5 hours, copolymerization emulsion solid content 32%.

[0050] Step (4): 0.1 mol / L citric acid to adjust pH 5.8, 26℃ stirring for 17 minutes; spray drying inlet 185℃, outlet 82℃, 80 mesh screen.

[0051] Example 5 Raw materials in step (1) (weight parts) Nano-silica 15 parts, γ-glycidoxypropyltrimethoxysilane 3 parts, deionized water 60 parts, butyl acrylate 20 parts, methyl methacrylate 7.5 parts, hydroxyethyl acrylate 4.5 parts, potassium persulfate 0.2 parts, chitosan quaternary ammonium salt 2 parts (degree of substitution 0.5), organic zirconium crosslinking agent 1.5 parts, citric acid 0.2 parts.

[0052] Key parameters of steps (2) to (4) Step (2): ultrasonic 50 kHz, 15 minutes; reaction temperature 70℃, pH 9.5, reaction time 2.5 hours, modified nano-silica particle size 110 nm.

[0053] Step (3): nitrogen protection, stirring speed 350 rpm, 75℃ reaction for 3.5 hours, copolymerization emulsion solid content 38%.

[0054] Step (4): 0.1 mol / L citric acid to adjust pH 6.2, 28℃ stirring for 19 minutes; spray drying inlet 195℃, outlet 88℃, 80 mesh screen.

[0055] Example 6 Raw materials in step (1) (parts by weight) Nano-silica 15 parts, γ-glycidoxypropyltrimethoxysilane 3 parts, deionized water 60 parts, butyl acrylate 15 parts, methyl methacrylate 10 parts, hydroxyethyl acrylate 4.5 parts, potassium persulfate 0.2 parts, chitosan quaternary ammonium salt 2 parts (degree of substitution 0.4), organic zirconium crosslinking agent 1.0 part, citric acid 0.2 part.

[0056] Key parameters of steps (2) to (4) Step (2): ultrasonic 50 kHz, 15 minutes; reaction temperature 70℃, pH 9, reaction time 2.5 hours, modified nano-silica particle size 100 nm.

[0057] Step (3): nitrogen protection, stirring speed 350 rpm, 75℃ reaction for 3.5 hours, copolymerization emulsion solid content 35%.

[0058] Step (4): 0.1 mol / L citric acid to adjust pH 6.0, stirring at 27℃ for 18 minutes; spray drying inlet temperature 190℃, outlet temperature 85℃, and passing through an 80-mesh screen.

[0059] Example 7 Raw materials in step (1) (parts by weight) Nano-silica 15 parts, γ-glycidoxypropyltrimethoxysilane 3 parts, deionized water 60 parts, butyl acrylate 25 parts, methyl methacrylate 5 parts, hydroxyethyl acrylate 4.5 parts, potassium persulfate 0.2 parts, chitosan quaternary ammonium salt 2 parts (degree of substitution 0.4), organic zirconium crosslinking agent 1.0 part, citric acid 0.2 part.

[0060] Key parameters of steps (2) to (4) Step (2): ultrasonic 50 kHz, 15 minutes; reaction temperature 70℃, pH 9, reaction time 2.5 hours, modified nano-silica particle size 100 nm.

[0061] Step (3): nitrogen protection, stirring speed 350 rpm, 75℃ reaction for 3.5 hours, copolymerization emulsion solid content 35%.

[0062] Step (4): 0.1 mol / L citric acid to adjust pH 6.0, stirring at 27℃ for 18 minutes; spray drying inlet temperature 190℃, outlet temperature 85℃, and passing through an 80-mesh screen.

[0063] Anti-pilling performance test Eight groups of pure cotton knitted fabrics (200g / m²) with the same specifications were selected as samples, wherein samples 1 to 7 were treated with the anti-pilling agents prepared in Examples 1 to 7 (treatment process: padding with a working solution at a concentration of 8%, pick-up rate of 80%, pre-drying at 105°C for 3 minutes, and curing at 160°C for 2 minutes); and sample 8 was a blank sample without any treatment.

[0064] The pilling performance of the above eight samples was tested by using a YG(B)401T Martindale abrasion tester, and the test parameters were set according to GB / T4802.2-2008 “Determination of the pilling behavior of textile - Part 2: modified Martindale method”. Sample size: a 90mm diameter circular sample was fixed on a sample holder. Abrasive: standard wool cloth (in accordance with GB / T4802.2); Pressure: 4.9N (500gf); Friction times: 5000 times; Rating method: after the test, the sample was compared with a standard sample, and the pilling grade (1-5, with 5 being the best) was evaluated.

[0065] The test results are as follows: Sample No. Corresponding treatment Pilling grade Phenomenon description 1 Example 1 reagent finishing 4.0 level Surface slightly pilling, no obvious ball, fabric appearance basically flat 2 Example 2 reagent finishing 3.5 level A small amount of short hair on the surface, occasionally 1-2 small pills (diameter <0.5mm), overall appearance good 3 Example 3 reagent finishing 4.5 level Surface almost no pilling, no pills, fabric texture clear, close to the untested state 4 Example 4 reagent finishing 3.8 level A small amount of pilling on the surface, sporadic small pills (diameter <0.3mm), without affecting the overall appearance 5 Example 5 reagent finishing 4.2 level Surface very slight pilling, no pills, fabric flatness maintained well 6 Example 6 reagent finishing 4.2 level Surface slightly pilling, no pills (due to high proportion of hard monomers, slightly better wear resistance) 7 Example 7 reagent finishing 3.8 level A small amount of pilling on the surface, occasionally small pills (due to high proportion of soft monomers, pilling slightly higher than sample 6, but softer hand feel) 8 Blank sample 2.0 level Surface a large amount of pilling, dense distribution of pills (diameter 0.5-1mm), fabric appearance rough, texture blurred Result analysis The pilling grades of samples 1 to 7 treated with the agents of Examples 1 to 7 were significantly higher than that of the blank sample (sample 8), which proved that the anti-pilling agent of the present application could effectively improve the anti-pilling performance of pure cotton knitted fabrics. Example 3 (sample 3) had the highest amount of nano-silica and the most compact covalent hybrid network, and thus had the best anti-pilling effect (4.5 grade). The comparison between samples 6 and 7 showed that increasing the proportion of hard monomers (methyl methacrylate) in the acrylate monomers could enhance the anti-pilling performance, while increasing the proportion of soft monomers (butyl acrylate) could slightly reduce the anti-pilling performance but improve the hand feeling, which was consistent with the previous emulsion polymerization mechanism.

[0066] Washing resistance test The same eight samples (samples 1 to 7 were pure cotton knitted fabrics treated with the anti-pilling agents prepared in Examples 1 to 7, and sample 8 was a blank sample without treatment) as in the anti-pilling performance test were subjected to a washing resistance test, and the specific steps were as follows: The finished fabric is subjected to water washing treatment according to the A (1) procedure in GB / T 3921-2008 "Textiles Color Fastness Test Soaping Fastness": the sample is placed in a water solution containing standard soap flakes (5 g / L) (bath ratio 1:50), and stirred at 40°C for 30 minutes, then taken out and rinsed with flowing water for 5 minutes, and naturally dried; the above operation is repeated for 50 cycles, and finally the fabric is placed for 24 hours before testing.

[0067] The 8 groups of samples after water washing are still subjected to pilling performance testing by using a YG (B) 401T Martindale abrasion tester, and the test parameters are the same as those in the anti-pilling performance test (diameter 90 mm sample, standard wool cloth abrasive, 4.9 N pressure, 5000 rubs, and rating according to GB / T 4802.2-2008 "Textiles Fabric Pilling Performance Test Part 2: Modified Martindale Method").

[0068] The test results are as follows: Sample No. Corresponding treatment Pilling grade after 50 times washing Phenomenon description 1 Example 1 reagent finishing 3.5 level Surface pilling slightly more than initial test, occasionally small pills (diameter <0.3mm), overall appearance maintained well 2 Example 2 reagent finishing 3.0 level Surface pilling significantly, a small amount of pills (diameter 0.3-0.5mm), but still better than blank sample 3 Example 3 reagent finishing 4.0 level Surface slightly pilling, no pills (covalent hybrid network wash resistance outstanding, close to un-washed state) 4 Example 4 reagent finishing 3.2 level Surface pilling moderate, sporadic pills, performance retention better than sample 2 5 Example 5 reagent finishing 3.8 level Surface very slight pilling, no pills (organic zirconium cross-linking enhancement effect significant) 6 Example 6 reagent finishing 3.7 level Surface pilling less, no pills (hard monomer formed film layer wear resistance still stable after washing) 7 Example 7 reagent finishing 3.3 level Surface pilling more than sample 6, a small amount of small pills (soft monomer film layer wash resistance slightly weaker but better than blank sample) 8 Blank sample 1.5 level Surface severe pilling, dense pills (diameter 1-2mm), fabric structure loose, appearance rough and unbearable Result analysis The pilling grade of the samples (1-7) treated by the reagent of the present application is still maintained at 3 or above after 50 times of washing, which is significantly higher than that of the blank sample (1.5), proving that the covalent hybrid network and cross-linking structure can effectively resist the mechanical friction and chemical action in the washing process, and solving the problem of poor washing resistance of traditional auxiliaries.

[0069] Example 3 (sample 3) and example 5 (sample 5) perform best, which confirms that when the amount of nano-silica is higher or the proportion of organic zirconium cross-linking agent is increased, the film layer structure is more stable, and the washing resistance is obviously improved.

[0070] The comparison of samples 6 and 7 shows that the film layer with a high proportion of hard monomers retains better anti-pilling performance after repeated washing, which is consistent with the mechanism of "hard monomers enhancing film layer strength".

[0071] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. It can be understood that for ordinary skilled persons in the art, equivalent replacement or change can be made according to the technical solution and inventive concept of the present application, and all these changes or replacements shall fall within the protection scope of the present application.

Claims

1. A method for preparing an anti-pilling agent, characterized in that: The following steps are involved: (1) Raw material preparation: weigh 10-20 parts of nano-silica, 2-4 parts of silane coupling agent, 50-70 parts of deionized water, 15-25 parts of butyl acrylate, 5-10 parts of methyl methacrylate, 3-6 parts of hydroxyethyl acrylate, 0.1-0.3 parts of potassium persulfate, 1-3 parts of chitosan quaternary ammonium salt, 0.5-1.5 parts of organic zirconium crosslinking agent, and 0.1-0.3 parts of citric acid; (2) Nano-silica modification: Nano-silica was dispersed in deionized water, silane coupling agent was added, and the mixture was stirred and reacted at 60-80°C and pH 8-10 for 2-3 hours to obtain modified nano-silica with surface grafted active groups, and the average particle size was controlled to be 80-120 nm; (3) Emulsion polymerization: Modified nano-silica was mixed with butyl acrylate, methyl methacrylate, and hydroxyethyl acrylate, potassium persulfate initiator was added, and emulsion polymerization was carried out at 75°C for 3.5 hours to prepare a copolymer emulsion; (4) Compounding treatment: Add chitosan quaternary ammonium salt to the copolymer emulsion, stir evenly and then add organic zirconium cross-linking agent, adjust the pH of the system to 6.0±1.0 with citric acid, stir at 25~30℃ for 15~20 minutes to prepare anti-pilling agent emulsion, and obtain solid product after spray drying.

2. The preparation method of the anti-pilling agent according to claim 1, wherein: The silane coupling agent in step (1) is γ-glycidyloxypropyltrimethoxysilane, and the weight ratio of nano-silica to the silane coupling agent is 5:

1.

3. The preparation method of the anti-pilling agent according to claim 1, wherein The degree of substitution of the chitosan quaternary ammonium salt in step (1) is 0.3-0.

5.

4. The preparation method of the anti-pilling agent according to claim 1, wherein When the nano-silica is dispersed in deionized water in step (2), ultrasonic dispersion treatment is adopted, the ultrasonic frequency is 40-60 kHz, and the ultrasonic time is 10-20 minutes.

5. The preparation method of the anti-pilling agent according to claim 1, wherein The pH value of the reaction system in step (2) is adjusted to 8-10 by adding sodium hydroxide solution.

6. The method for preparing the anti-pilling agent according to claim 1, wherein: In step (3), the emulsion polymerization reaction is carried out under nitrogen protection and a stirring speed of 300-400 rpm.

7. The preparation method according to claim 1, characterized in that The solid content of the copolymer emulsion in step (3) is 30-40%.

8. The method for preparing the anti-pilling agent according to claim 1, wherein: When the pH of the system is adjusted to 6.0±1.0 in step (4), a 0.1 mol / L aqueous solution of citric acid is added dropwise and monitored in real time using a pH meter with an accuracy of ±0.

01.

9. The method for preparing the anti-pilling agent according to claim 1, wherein: The anti-pilling agent emulsion prepared in step (4) is spray-dried with an air inlet temperature of 180-200°C and an air outlet temperature of 80-90°C. After drying, it is crushed through an 80-mesh sieve to obtain a solid product with uniform particle size.

10. An anti-pilling agent, characterized in that: The anti-pilling agent is prepared by the preparation method of any one of claims 1 to 9.

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