Friction-resistant anti-pilling knitted fabric and preparation method thereof

Abstract

The invention relates to the technical field of fabrics, in particular to a friction-resistant and anti-pilling knitted fabric and a preparation method thereof. The preparation method comprises the following steps: dissolving an aramid polymer in concentrated sulfuric acid to prepare a spinning solution, stirring for defoaming treatment, then spinning the spinning solution, solidifying and shaping, and finally washing, stretching and drying to obtain the aramid fiber, the preparation method comprises the following steps: stirring polyether polyol, diisocyanate, ethylene glycol, gamma-aminopropyltriethoxysilane and a catalyst for reaction to obtain a modified polyurethane elastomer; heating the modified polyurethane elastomer, uniformly coating the surface of the aramid fiber with the modified polyurethane elastomer to obtain a core-shell structure composite fiber, then spinning, cooling, oiling, and finally winding into the yarn; weaving the yarns to obtain gray cloth, and performing crosslinking treatment and nano coating treatment to obtain the friction-resistant and anti-pilling knitted fabric. The fabric can effectively resist friction external force and can effectively inhibit pilling.

Description

Technical Field

[0001] The invention relates to the technical field of fabrics, and in particular to a friction-resistant and pilling-resistant knitted fabric and a preparation method thereof. Background Art

[0002] Knitted fabrics are widely used in the clothing industry due to their soft texture, good extensibility and elasticity. However, their inherent defects limit their further development. For example, the yarn structure is loose, and fibers are easily detached from the yarn, resulting in poor wear resistance of the fabric. After frequent friction, the surface is prone to pilling, seriously affecting the appearance and service life. This problem is particularly prominent in areas prone to friction, such as collars, cuffs, and elbows. Traditional knitted wool sweaters, like these, will show obvious pilling after being worn several times. At the same time, the coil structure of knitted fabrics is unstable, and the coils are easily transferred during use, causing the fabric to deform, affecting the wearing effect and version. During sports and daily activities, knitted garments are often deformed due to friction and stretching and cannot maintain their original shape.

[0003] Existing improvement methods have numerous shortcomings. While changing the fiber raw material, such as using anti-pilling acrylic fibers, can improve the pilling problem to some extent, it can also reduce other fabric properties, such as warmth and moisture absorption, and comes at a high cost. In terms of post-finishing processes, coating or adding anti-pilling agents has a short-lasting effect, significantly reducing performance after repeated washings. Furthermore, coatings can affect the fabric's breathability and feel, making it less comfortable to wear. In complex environments, such as high-intensity outdoor sports and industrial operations, the performance of existing knitted fabrics is insufficient.

[0004] Therefore, developing a knitted fabric that is resistant to friction and pilling and a preparation method thereof are of great practical significance. Summary of the Invention

[0005] To address the above technical problems, the present invention provides a friction-resistant and pilling-resistant knitted fabric and its preparation method. The core layer of aramid fiber effectively resists external frictional forces, significantly reducing fiber breakage and displacement during friction, fundamentally reducing the occurrence of pilling. A modified polyurethane elastomer is used as the shell layer, tightly encapsulating the aramid fiber to form a core-shell composite fiber, further enhancing the overall wear resistance of the fabric. The polyurethane elastomer's inherent flexibility and elasticity buffer external frictional forces, preventing direct damage to the fiber surface. Its excellent bonding with the aramid fiber prevents relative sliding and entanglement between fibers, effectively suppressing pilling.

[0006] To this end, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides, in an optional embodiment, a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0008] S1: Aramid polymer is dissolved in concentrated sulfuric acid to prepare a spinning solution, and the solution is stirred and mixed for degassing. The spinning solution is then spun and placed into a coagulation solution for coagulation and setting. The solution is then washed, stretched, and dried to obtain aramid fiber.

[0009] S2: mixing and stirring polyether polyol, diisocyanate, ethylene glycol, γ-aminopropyltriethoxysilane and a catalyst to obtain a modified polyurethane elastomer;

[0010] S3: heating the modified polyurethane elastomer and uniformly coating the surface of the aramid fiber to obtain a core-shell structure composite fiber, spinning, cooling, and oiling the core-shell structure composite fiber, and finally winding it into a yarn;

[0011] S4: weaving the yarn to obtain a grey cloth, and then performing a cross-linking treatment and a nano-coating treatment on the grey cloth to obtain the friction-resistant and anti-pilling knitted fabric.

[0012] In the present invention, the high strength and high modulus properties of aramid fiber enable the composite fiber to maintain its integrity when subjected to friction and external forces, and not be easily worn or broken. Its molecular structure contains a large number of benzene rings and amide bonds, forming a highly ordered crystalline structure, which gives the fiber excellent mechanical properties. When the fabric is subjected to friction, the aramid fiber core can effectively disperse the stress and prevent the fiber from being quickly damaged during the friction process. The introduction of siloxane groups makes the surface of the polyurethane elastomer shell have a lower friction coefficient. The bond energy of the silicon-oxygen bond (Si-O) is high, and the organic group connected to the silicon atom has a certain steric hindrance, making the fiber surface smoother. When rubbed with other objects, it can reduce the generation of friction and reduce the degree of wear on the fiber surface. The isocyanate group reacts with the hydroxyl group on the surface of the aramid fiber to form a carbamate bond. This chemical bonding strengthens the bonding force between the core and the shell, ensuring that the core-shell structure of the composite fiber will not separate during the processing and use of the fabric, maintaining the overall performance of the fiber. The polyurethane elastomer itself has good elasticity and can adapt to the stretching and deformation of knitted fabrics during wearing. When the fabric is stretched, the polyurethane elastomer shell can undergo elastic deformation without breaking easily like rigid materials. At the same time, it can also protect the internal aramid fibers from excessive stretching, ensuring that the fabric has good strength while also having a certain degree of flexibility and comfort to wear.

[0013] Preferably, in step S1, the aramid polymer is selected from one of poly(p-phenylene terephthalamide) or poly(m-phenylene isophthalamide) or a mixture of the two; and / or the dissolution temperature is 0-10°C; and / or the volume concentration of the concentrated sulfuric acid is greater than 98%; and / or the mass fraction of the aramid polymer in the spinning solution is 18-22%; and / or the degassing treatment is performed by vacuum degassing, which comprises placing the spinning solution in a sealed container, evacuating the container to 0.01-0.05 MPa, and maintaining the vacuum for 30-60 minutes. During the spinning, the diameter of the spinneret is 0.08-0.12 mm, and the spinning rate is 0.5-1.5 m / min; and / or the coagulation liquid is a mixture of water and an organic solvent, the volume ratio of water to organic solvent is 3-5:5-7, and the organic solvent is selected from one or more of dimethyl sulfoxide, dimethylformamide, and N-methylpyrrolidone; and / or the temperature of the coagulation liquid is 20-30° C.; and / or the washing time is 10-20 minutes; and / or the stretching ratio of the stretching is 3-5 times, and the stretching temperature is 150-180° C.; and / or the drying temperature is 120-150° C.

[0014] Preferably, in step S2, the polyether polyol is selected from polytetrahydrofuran or polyoxypropylene glycol, or a mixture thereof; and / or the diisocyanate is diphenylmethane diisocyanate; and / or the mass ratio of the polyether polyol, diisocyanate, ethylene glycol, and γ-aminopropyltriethoxysilane is (100-120):(50-60):(10-15):(5-8); the catalyst is dibutyltin dilaurate, and the amount of the catalyst added is 0.05-0.1% of the total mass of the polyether polyol, diisocyanate, ethylene glycol, and γ-aminopropyltriethoxysilane; and / or the stirring reaction temperature is 60-80°C, and the reaction time is 3-5 hours.

[0015] Preferably, in step S3, the mass ratio of the modified polyurethane elastomer to the aramid fiber is 1:3-5; and / or the heating temperature is 180-200°C; and / or the spinning temperature is 180-200°C and the pressure is 0.8-1.2 MPa; and / or the cooling temperature is 15-20°C, and the oiling rate is 0.5-1%.

[0016] Preferably, in step S4, when the weaving is performed, the tension of the yarn is 3-5 cN / dtex; and / or the needle pitch is 24-28 needles / inch. The cross-linking treatment is performed by soaking the grey cloth in a cross-linking agent solution and reacting at 40-60°C for 30-60 minutes; the cross-linking agent solution is prepared by dissolving glutaraldehyde in deionized water to form a solution with a mass fraction of 3-5%, and adding a sodium carbonate solution with a mass fraction of 5-10% to adjust the pH to 7-9; the mass ratio of the grey cloth to the cross-linking agent solution is 1:10-15; after the cross-linking treatment, the cross-linked fabric is rinsed with water and dried at 60-80°C. The nano-coating treatment method is as follows: the fabric dried after cross-linking treatment is immersed in nano-silica sol for 10-15 minutes, then dried at 80-100°C for 20-30 minutes, and finally cured at 120-150°C for 15-20 minutes; the nano-silica sol is prepared by mixing tetraethyl orthosilicate, ethanol, water and hydrochloric acid, and stirring at 25°C for 2-3 hours to form a transparent nano-silica sol; the mass ratio of tetraethyl orthosilicate, ethanol, water and hydrochloric acid is (10-15): (30-40): (10-15): (0.1-0.2); the mass fraction of the hydrochloric acid is 36-38%.

[0017] In the present invention, the crosslinking agent forms a covalently linked network between the fabric fibers. This network acts like a bridge between the fibers, strengthening the connection between them. When the fabric is subjected to friction, the fibers are less likely to shift or slide relative to each other, thereby reducing fiber wear and breakage. Furthermore, the crosslinked network prevents the formation of fuzz on the fiber surface, which often occurs when fiber ends are pulled out of the fabric surface and entangled with each other due to friction. After the crosslinking treatment, the fiber ends are fixed in the crosslinked network, making them difficult to pull out and form fuzz, thereby improving the fabric's pilling resistance. The nano-silica coating forms a hard and smooth protective film on the fabric surface. Nano-silica's high hardness allows it to withstand a certain degree of friction, reducing direct wear on the fabric's surface fibers. Its low surface energy reduces the contact area between external objects and the fabric surface, further reducing friction. Furthermore, the nano-silica coating fills in minor surface defects, making the fiber surface smoother and reducing the causes of pilling. Furthermore, due to its excellent chemical stability, nano-silica protects the fabric fibers from external chemical attack, extending the fabric's service life.

[0018] In a second aspect, the present invention provides, in an optional embodiment, a friction-resistant and anti-pilling knitted fabric prepared by the above-mentioned preparation method.

[0019] Compared with the prior art, the present invention has one of the following beneficial effects:

[0020] 1. This fabric utilizes an aramid fiber core layer, effectively resisting external frictional forces and significantly reducing fiber breakage and displacement during friction, fundamentally reducing pilling. A modified polyurethane elastomer shell tightly encapsulates the aramid fiber, creating a core-shell composite fiber structure that further enhances the overall wear resistance of the fabric. The polyurethane elastomer's inherent flexibility and elasticity buffer external frictional forces, preventing direct damage to the fiber surface. Furthermore, its excellent bonding with the aramid fiber prevents relative sliding and entanglement between fibers, effectively suppressing pilling. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. 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.

[0022] In the following examples and comparative examples, the crosslinker solution was prepared by dissolving glutaraldehyde in deionized water to prepare a 5% by mass solution, and then adding 8% by mass sodium carbonate solution to adjust the pH to 8.

[0023] The preparation method of the nano-silica sol is as follows: 12 kg of ethyl orthosilicate, 35 kg of ethanol, 14 kg of water and 0.15 kg of hydrochloric acid (mass fraction of 36%) are mixed, and then stirred at 25° C. for 3 hours to form a transparent nano-silica sol.

[0024] In the following examples and comparative examples, poly(p-phenylene terephthalamide) was purchased from Dongguan Kaixili Plastic Raw Materials Co., Ltd., polytetrahydrofuran was purchased from Sichuan Tianhua Chemical Group Co., Ltd. with the model number PTMEG1800, γ-aminopropyltriethoxysilane was purchased from Qingdao Xuxin Chemical Co., Ltd. with the model number KH-550, and diphenylmethane diisocyanate was purchased from Shandong Desenlai Chemical Co., Ltd.

[0025] The technical solution of the present invention will be described below with reference to embodiments.

[0026] Example 1

[0027] This embodiment provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0028] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (a mixture of dimethyl sulfoxide and water in a volume ratio of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0029] S2: 100 kg of polytetrahydrofuran, 55 kg of diphenylmethane diisocyanate, 12 kg of ethylene glycol and 6 kg of γ-aminopropyltriethoxysilane were added to a reactor, and then 0.173 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70°C for 4 hours. Nitrogen was introduced for protection during the reaction to obtain a modified polyurethane elastomer.

[0030] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0031] S4: The yarn is weaved (the yarn tension is controlled to be 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a crosslinker solution (the mass ratio of the grey cloth to the crosslinker solution is 1:12) and reacted at 50°C for 45 minutes. After the reaction is completed, the fabric is rinsed with water and dried at 70°C. The dried fabric is then immersed in nano-silica sol for 12 minutes, then dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0032] Example 2

[0033] This embodiment provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0034] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0035] S2: 100 kg of polytetrahydrofuran, 60 kg of diphenylmethane diisocyanate, 12 kg of ethylene glycol and 6 kg of γ-aminopropyltriethoxysilane were added to a reactor, and then 0.178 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70°C for 4 hours. Nitrogen was introduced for protection during the reaction to obtain a modified polyurethane elastomer.

[0036] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0037] S4: The yarn is weaved (the yarn tension is controlled to be 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a crosslinker solution (the mass ratio of the grey cloth to the crosslinker solution is 1:12) and reacted at 50°C for 45 minutes. After the reaction is completed, the fabric is rinsed with water and dried at 70°C. The dried fabric is then immersed in nano-silica sol for 12 minutes, then dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0038] Example 3

[0039] This embodiment provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0040] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0041] S2: 100 kg of polytetrahydrofuran, 50 kg of diphenylmethane diisocyanate, 12 kg of ethylene glycol and 6 kg of γ-aminopropyltriethoxysilane were added to a reactor, and then 0.168 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70°C for 4 hours. Nitrogen was introduced for protection during the reaction to obtain a modified polyurethane elastomer.

[0042] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0043] S4: The yarn is weaved (the yarn tension is controlled to be 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a crosslinker solution (the mass ratio of the grey cloth to the crosslinker solution is 1:12) and reacted at 50°C for 45 minutes. After the reaction is completed, the fabric is rinsed with water and dried at 70°C. The dried fabric is then immersed in nano-silica sol for 12 minutes, then dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0044] Comparative Example 1

[0045] This comparative example provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0046] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0047] S2: 100 kg of polytetrahydrofuran, 12 kg of ethylene glycol and 6 kg of γ-aminopropyltriethoxysilane were added to a reactor, and then 0.118 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70° C. for 4 hours. Nitrogen was introduced during the reaction for protection to obtain a modified polyurethane elastomer.

[0048] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0049] S4: The yarn is weaved (the yarn tension is controlled to be 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a crosslinker solution (the mass ratio of the grey cloth to the crosslinker solution is 1:12) and reacted at 50°C for 45 minutes. After the reaction is completed, the fabric is rinsed with water and dried at 70°C. The dried fabric is then immersed in nano-silica sol for 12 minutes, then dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0050] Comparative Example 2

[0051] This comparative example provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0052] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0053] S2: Spinning the aramid fiber. After spinning, the fiber is cooled at 20°C and lubricated with an amino silicone oil emulsion (5% by mass) by padding with an oiler. The oiler rotates at 15 rpm and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). The fiber is then wound into yarn.

[0054] S3: The yarn is weaved (the yarn tension is controlled at 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a crosslinker solution (the mass ratio of the grey cloth to the crosslinker solution is 1:12) and reacted at 50°C for 45 minutes. After the reaction is completed, the fabric is rinsed with water and dried at 70°C. The dried fabric is then immersed in nano-silica sol for 12 minutes, then dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0055] Comparative Example 3

[0056] This comparative example provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0057] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0058] S2: 100 kg of polytetrahydrofuran, 55 kg of diphenylmethane diisocyanate, and 12 kg of ethylene glycol were added to a reactor, and then 0.167 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70° C. for 4 hours. Nitrogen was introduced for protection during the reaction to obtain a modified polyurethane elastomer.

[0059] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0060] S4: The yarn is weaved (the yarn tension is controlled to be 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a crosslinker solution (the mass ratio of the grey cloth to the crosslinker solution is 1:12) and reacted at 50°C for 45 minutes. After the reaction is completed, the fabric is rinsed with water and dried at 70°C. The dried fabric is then immersed in nano-silica sol for 12 minutes, then dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0061] Comparative Example 4

[0062] This comparative example provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0063] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0064] S2: 100 kg of polytetrahydrofuran, 55 kg of diphenylmethane diisocyanate, 12 kg of ethylene glycol and 6 kg of γ-aminopropyltriethoxysilane were added to a reactor, and then 0.173 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70°C for 4 hours. Nitrogen was introduced for protection during the reaction to obtain a modified polyurethane elastomer.

[0065] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0066] S4: The yarn is knitted (the yarn tension is controlled at 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in nano-silica sol for 12 minutes, dried at 90°C for 25 minutes, and finally cured at 130°C for 18 minutes to obtain a knitted fabric.

[0067] Comparative Example 5

[0068] This comparative example provides a method for preparing a friction-resistant and anti-pilling knitted fabric, comprising the following steps:

[0069] S1: Dissolve poly(p-phenylene terephthalamide) in concentrated sulfuric acid (volume concentration of 98%) at 5°C to prepare a spinning solution (in the spinning solution, the mass fraction of poly(p-phenylene terephthalamide) is 20%). After stirring and mixing, place it in a sealed container, evacuate to 0.05MPa, and maintain for 50 minutes. Extrude the spinning solution through a spinneret with a spinneret diameter of 0.10mm and a spinning rate of 1m / min. The solution is then coagulated into a coagulation solution at a temperature of 25°C (the coagulation solution is a mixture of dimethyl sulfoxide and water, with a volume ratio of dimethyl sulfoxide to water of 5.5:4.5). The coagulated aramid fiber is washed in a water tank and rinsed with a large amount of clean water to remove sulfuric acid and organic solvents on the surface. The washing time is 18 minutes. The fiber is then stretched with a stretching ratio of 3 times and a stretching temperature of 160°C. Finally, it is dried at 130°C to obtain a high-strength aramid fiber.

[0070] S2: 100 kg of polytetrahydrofuran, 55 kg of diphenylmethane diisocyanate, 12 kg of ethylene glycol and 6 kg of γ-aminopropyltriethoxysilane were added to a reactor, and then 0.173 kg of dibutyltin dilaurate catalyst was added to the reactor. The mixture was stirred and reacted at 70°C for 4 hours. Nitrogen was introduced for protection during the reaction to obtain a modified polyurethane elastomer.

[0071] S3: 100kg of modified polyurethane elastomer is put into the barrel of the ZSE twin-screw extruder produced by Nanjing Zhongsen Extrusion Machinery Co., Ltd., heated and melted at 190°C, and the molten modified polyurethane elastomer is conveyed to the coating mold through the screw (the coating mold is an annular spinneret die in a composite spinning assembly suitable for large-capacity annular spinneret spinning produced by Handan Hongda Chemical Fiber Machinery Co., Ltd.), and the annular gap width of its annular distribution channel is 0.3mm. At the same time, 400kg of aramid fiber is introduced into the central channel of the coating mold through a guide roller to ensure that the fiber moves stably along the axial direction, and the travel speed is controlled to 8m / min. The pressure in the mold is adjusted to 0.8MPa so that the molten material fits tightly to the surface of the aramid fiber under pressure to achieve preliminary coating. Subsequently, the composite fiber enters a constant temperature shaping section with a length of 1.2m. The constant temperature shaping section adopts a CT-C series hot air circulation oven produced by Changzhou Instant Drying Equipment Co., Ltd. and is maintained at 190°C for 5 seconds to allow the coating layer to fully level and combine with the fiber surface, completing uniform coating to form a core-shell structure composite fiber. After the spinning is completed, it is cooled at 20°C and an amino silicone oil emulsion (mass concentration of 5%) is used as an oil agent. The oil is applied by oiling with an oil wheel padding method. The oil wheel speed is 15r / min, and the oiling rate is controlled to be 0.8% (based on the mass of the composite fiber). Finally, it is wound into yarn;

[0072] S4: The yarn is knitted (the yarn tension is controlled at 4 cN / dtex and the needle pitch of the textile machine is 26 needles / inch) to obtain a grey cloth, which is then immersed in a cross-linking agent solution (the mass ratio of the grey cloth to the cross-linking agent solution is 1:12), and reacted at 50°C for 45 minutes. After the reaction is completed, the yarn is rinsed with water and dried at 70°C to obtain a knitted fabric.

[0073] Experimental example

[0074] The knitted fabrics prepared in Examples 1-3 and Comparative Examples 1-5 were tested for friction resistance and anti-pilling properties. The test method was as follows:

[0075] Anti-pilling: According to the method in GB / T4802.1-2008;

[0076] Friction resistance: According to the method in GB / T 3920-2008.

[0077] The test results are shown in Table 1.

[0078] Table 1 Performance test of knitted fabrics prepared in Examples 1-3 and Comparative Examples 1-5

[0079]

[0080]

[0081] As can be seen from Table 1, compared with Example 1, the anti-pilling grade of Comparative Example 1 is level 3, and there is some fuzzing and a small amount of small balls after friction. This shows that diisocyanate plays an important role in the reaction. It can react with polytetrahydrofuran, ethylene glycol, etc. to form a polyurethane elastomer with a specific structure. The lack of diisocyanate will lead to an imperfect structure of the prepared modified polyurethane elastomer, which cannot be well coated on the surface of the aramid fiber, resulting in a loose core-shell structure of the composite fiber. Fiber wear and pilling are likely to occur during friction, thereby reducing the anti-pilling and friction resistance of the fabric.

[0082] Compared with Example 1, the anti-pilling grade of Comparative Example 2 is only Level 2. After friction, pilling is obvious, there are many small pills, and the surface of the fabric is slightly worn. This shows that the modified polyurethane elastomer is used as a shell layer to cover the surface of the aramid fiber, which can buffer the external friction force, avoid direct damage to the fiber surface, and prevent relative sliding and entanglement between fibers. Due to the lack of this layer of coating, the aramid fiber in Comparative Example 2 is directly exposed and easily damaged during friction. Relative movement between fibers is also likely to occur, resulting in serious pilling and a significant decrease in friction resistance.

[0083] Compared with Example 1, the anti-pilling grade of Comparative Example 3 is Level 3, and there is a certain amount of pilling after friction, and there are a small number of small balls. This shows that the siloxane group in γ-aminopropyltriethoxysilane can improve the interfacial bonding force between the polyurethane elastomer and the aramid fiber and enhance the stability of the core-shell structure. The lack of γ-aminopropyltriethoxysilane will make the bond between the modified polyurethane elastomer and the aramid fiber less firm. Under the action of friction, the coating layer is easy to fall off, resulting in the exposure of the aramid fiber, and then pilling occurs, which reduces the performance of the fabric.

[0084] Compared with Example 1, the anti-pilling grade of Comparative Example 4 is Level 3, and there is slight pilling and individual small balls after friction. This shows that the cross-linking treatment can form a covalent cross-linking network between the fabric fibers, making the fiber connections tighter, reducing the relative displacement and sliding of the fibers, and limiting the generation of fuzz. Due to the lack of cross-linking treatment, the fibers in Comparative Example 4 are not tightly bonded, and fuzz and small balls are easily generated during friction, resulting in reduced anti-pilling and friction resistance.

[0085] Compared with Example 1, the anti-pilling grade of Comparative Example 5 is Level 3, and there is slight pilling after friction, with individual small balls. It can be seen that the nano-silica coating can form a hard and smooth protective film on the surface of the fabric, reduce the direct wear of the fibers on the surface of the fabric, reduce friction, and fill the tiny defects on the fiber surface. Comparative Example 5 lacks nano-coating treatment, and the fabric surface is not effectively protected. Pilling is prone to occur during friction, and the anti-pilling and friction resistance are slightly worse than those of Example 1.

[0086] The present invention uses aramid fiber as the core layer, which can effectively resist external friction forces, significantly reduce the breakage and displacement of fibers during friction, and fundamentally reduce the occurrence of pilling. The modified polyurethane elastomer is used as the shell layer to tightly coat the aramid fiber to form a core-shell structure composite fiber, which further enhances the wear resistance of the overall fabric. The flexibility and elasticity of the polyurethane elastomer itself can buffer external friction forces and avoid direct damage to the fiber surface. Its good adhesion with the aramid fiber prevents relative sliding and entanglement between fibers, effectively suppressing pilling. The isocyanate group reacts with the hydroxyl group on the surface of the aramid fiber to form a carbamate bond. This chemical bonding strengthens the bonding force between the core and the shell, ensuring that the core-shell structure of the composite fiber will not separate during the processing and use of the fabric, maintaining the overall performance of the fiber. The polyurethane elastomer itself has good elasticity and can adapt to the stretching and deformation of knitted fabrics during wear. When the fabric is stretched, the polyurethane elastomer shell can undergo elastic deformation without breaking easily like rigid materials. At the same time, it can also protect the internal aramid fibers from excessive stretching, ensuring that the fabric has good strength while also having a certain degree of flexibility and comfort to wear.

[0087] Although the principles of the present invention have been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing a friction-resistant and anti-pilling knitted fabric, characterized in that: The following steps are involved: S1: Aramid polymer is dissolved in concentrated sulfuric acid to prepare a spinning solution, which is stirred for degassing. The spinning solution is then spun and placed in a coagulation solution for coagulation and setting. The solution is then washed, stretched, and dried to obtain aramid fiber. S2: mixing and stirring polyether polyol, diisocyanate, ethylene glycol, γ-aminopropyltriethoxysilane and a catalyst to obtain a modified polyurethane elastomer; S3: heating the modified polyurethane elastomer and uniformly coating the surface of the aramid fiber to obtain a core-shell structure composite fiber, spinning, cooling, and oiling the core-shell structure composite fiber, and finally winding it into a yarn; S4: weaving the yarn to obtain a grey cloth, and then performing a cross-linking treatment and a nano-coating treatment on the grey cloth to obtain the friction-resistant and anti-pilling knitted fabric.

2. The method for preparing the friction-resistant and anti-pilling knitted fabric according to claim 1, characterized in that: In step S1, the aramid polymer is selected from poly (p-phenylene terephthalamide) or poly (m-phenylene isophthalamide) or a mixture of the two; and / or, The dissolving temperature is 0-10°C; and / or, The volume concentration of the concentrated sulfuric acid is greater than 98%; and / or, The mass fraction of the aramid polymer in the spinning solution is 18-22%; and / or, The degassing treatment is performed by vacuum degassing, which comprises placing the spinning solution in a sealed container, evacuating the container to a vacuum of 0.01-0.05 MPa, and maintaining the vacuum for 30-60 minutes.

3. The method for preparing the friction-resistant and anti-pilling knitted fabric according to claim 1, wherein: In step S1, during the spinning, the diameter of the spinneret is 0.08-0.12 mm, and the spinning rate is 0.5-1.5 m / min; and / or, The coagulation liquid is a mixture of water and an organic solvent, the volume ratio of water to organic solvent is 3-5:5-7, and the organic solvent is selected from one or more of dimethyl sulfoxide, dimethylformamide, and N-methylpyrrolidone; and / or, The temperature of the coagulation liquid is 20-30°C; and / or, The washing time is 10-20 minutes; and / or, The stretching ratio is 3-5 times and the stretching temperature is 150-180° C.; and / or, The drying temperature is 120-150°C.

4. The method for preparing the friction-resistant and pilling-resistant knitted fabric according to claim 1, wherein: In step S2, the polyether polyol is selected from polytetrahydrofuran or polyoxypropylene glycol or a mixture of the two; and / or, The diisocyanate is diphenylmethane diisocyanate; and / or, The mass ratio of the polyether polyol, diisocyanate, ethylene glycol and gamma-aminopropyltriethoxysilane is (100-120): (50-60): (10-15): (5-8).

5. The method for preparing the friction-resistant and pilling-resistant knitted fabric according to claim 1, wherein: In step S2, the catalyst is dibutyltin dilaurate, and the amount of the catalyst added is 0.05-0.1% of the total mass of the polyether polyol, diisocyanate, ethylene glycol and γ-aminopropyltriethoxysilane; and / or, The stirring reaction is carried out at a temperature of 60-80° C. and for 3-5 hours.

6. The method for preparing the friction-resistant and pilling-resistant knitted fabric according to claim 1, characterized in that: In step S3, the mass ratio of the modified polyurethane elastomer to the aramid fiber is 1:3-5; and / or, The heating temperature is 180-200° C.; and / or, The spinning temperature is 180-200° C. and the pressure is 0.8-1.2 MPa; and / or, The cooling temperature is 15-20° C., and the oiling rate is 0.5-1%.

7. The method for preparing the friction-resistant and pilling-resistant knitted fabric according to claim 1, wherein: In step S4, during the weaving, the tension of the yarn is 3-5 cN / dtex; and / or, The stitch length is 24-28 stitches per inch.

8. The method for preparing the friction-resistant and anti-pilling knitted fabric according to claim 1, characterized in that: In step S4, the cross-linking treatment is performed by soaking the grey cloth in a cross-linking agent solution and reacting the solution at 40-60° C. for 30-60 minutes; The crosslinking agent solution is prepared by dissolving glutaraldehyde in deionized water to prepare a solution with a mass fraction of 3-5%, and adding a sodium carbonate solution with a mass fraction of 5-10% to adjust the pH to 7-9; The mass ratio of the grey cloth to the cross-linking agent solution is 1:10-15; After the cross-linking treatment, the method further includes the steps of rinsing the cross-linked fabric with water and drying it at 60-80°C.

9. The method for preparing the friction-resistant and pilling-resistant knitted fabric according to claim 1, characterized in that: In step S4, the nano-coating treatment is performed by dipping the cross-linked and dried fabric into nano-silica sol for 10-15 minutes, followed by drying at 80-100° C. for 20-30 minutes, and finally curing at 120-150° C. for 15-20 minutes. The preparation method of the nano-silica sol is as follows: after mixing ethyl orthosilicate, ethanol, water and hydrochloric acid, stirring at 25° C. for 2-3 hours to form a transparent nano-silica sol; The mass ratio of the tetraethyl orthosilicate, ethanol, water and hydrochloric acid is (10-15): (30-40): (10-15): (0.1-0.2); The mass fraction of the hydrochloric acid is 36-38%.

10. A friction-resistant and anti-pilling knitted fabric prepared by the preparation method according to any one of claims 1 to 9.

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