A skin-friendly and warm knitted fabric

Abstract

This invention relates to a skin-friendly and warm knitted fabric, belonging to the field of textile technology. It includes a warm inner layer (1), a connecting layer (2), and a wear-resistant outer layer (3). The warm inner layer (1), connecting layer (2), and wear-resistant outer layer (3) are woven using a weft-knitted air-layer structure. The weft-knitted air-layer structure includes a six-way loop-forming system. The first and fourth loops of the six-way loop-forming system form the connecting layer (2), the second and fifth loops form the warm inner layer (1), and the third and sixth loop-forming systems form the wear-resistant outer layer (3). The fabric layers are stably connected, and the inner and outer layers are tightly woven together to form a single unit. Using a weft-knitted air-layer structure, the upper and lower layers of the fabric are tightly connected through the shrinkage effect of the spandex in the connecting layer, making it less prone to separation and wrinkling between the fabric layers. This results in greater durability than traditional composite fabrics, achieving a perfect balance between fabric structural stability and functionality.

Description

Technical Field

[0001] This invention belongs to the field of textiles, and specifically relates to a method for manufacturing a thermal insulation fabric. Background Technology

[0002] With the improvement of residents' living standards and the upgrading of consumption demands, functional textile fabrics have become a core research and development direction. Heat-generating fabrics, due to their excellent warmth retention properties, are widely used in thermal underwear, outdoor sportswear, medical care clothing, and other fields. Currently, heat-generating fabrics on the market are mainly divided into two categories: far-infrared active heat-generating fabrics and moisture-wicking passive heat-generating fabrics. Most products only have a single heat-generating function, with limited warmth retention, making it difficult to meet consumers' needs for efficient warmth retention.

[0003] Meanwhile, existing functional optimizations of heating fabrics have significant shortcomings: antibacterial functions are mostly achieved by adding chemical antibacterial agents, which not only cause skin irritation and poor warmth retention, but also lead to the antibacterial agents easily falling off after repeated washing, resulting in short-lived antibacterial effects; abrasion resistance is often achieved through simple blends of ordinary abrasion-resistant fibers, making the fabric prone to pilling and having a short abrasion lifespan, making it difficult to balance functionality and durability. For example, Chinese Patent Publication No. CN208290627U discloses a far-infrared heating knitted fabric, including a knitted surface layer and a knitted bottom layer, with multiple interlayers connected by partial connections between the knitted surface layer and the knitted bottom layer, and the interlayers filled with hydrogel. However, it only has a single far-infrared heating function, and its antibacterial performance relies on chemical antibacterial agents.

[0004] In addition, existing functional knitted fabrics generally use ordinary double-layer knitting technology, which has low interlayer bonding strength and is prone to problems such as interlayer separation, wrinkling, and deformation. Furthermore, the performance of functional fibers is easily damaged during the knitting process, resulting in a conflict between the fabric's structural stability and functionality. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a skin-friendly and warm fabric that is superior to the above-mentioned prior art. It has a skin-friendly and warm inner layer and a wear-resistant outer layer, and adopts a specific weaving structure and yarn, so that the two sides of the fabric have different functional properties, while significantly improving the connection strength between the outer layer and the inner layer.

[0006] The technical solution adopted by the present invention to solve the above problems is as follows: a skin-friendly and warm knitted fabric, characterized in that it includes a warm inner layer, a connecting layer, and a wear-resistant outer layer. The warm inner layer, the connecting layer, and the wear-resistant outer layer are woven into a weft-knitted air layer structure. The weft-knitted air layer structure includes a six-way loop-forming system. The first and fourth loops of the six-way loop-forming system form the connecting layer, the second and fifth loops form the warm inner layer, and the third and sixth loop-forming systems form the wear-resistant outer layer. The knitting yarn used for the warm inner layer is a blend of cotton fiber and modal fiber, the knitting yarn used for the connecting layer is spandex filament, and the knitting yarn used for the wear-resistant outer layer is wear-resistant polyester yarn.

[0007] Furthermore, the cotton and modal blended yarn has a count of 40–60S and a yarn length of 20–24 cm / 100 stitches; the spandex filament has a fineness of 20–35D and a yarn length of 8–10 cm / 100 stitches; and the abrasion-resistant polyester yarn has a yarn length of 22–26 cm / 100 stitches.

[0008] Furthermore, the cotton fiber is an antibacterial cotton fiber, and the preparation process is as follows: the cotton fiber is soaked in deionized water for 80-120 min, dried at 50-60℃ to a water content of 6-8%, and then activated with 30-45W helium plasma at a discharge gap of 2-3 mm for 40-75 s; then the activated cotton fiber is immersed in the grafting reaction solution, stirred at 50-80 r / min for 1-3 h, washed with anhydrous ethanol 3-5 times, and vacuum dried at 60-70℃ to constant weight; the mass ratio of cotton fiber to deionized water is 1:6-15, the mass ratio of cotton fiber to grafting reaction solution is 1:10-20, and the reaction temperature is 30-40℃.

[0009] Furthermore, the grafting reaction solution is a composite system of Artemisia argyi essential oil and dual initiators, and the solvent is a mixture of anhydrous ethanol and deionized water at a volume ratio of 7-8:2-3; the mass fraction of Artemisia argyi essential oil in the grafting reaction solution is 3-8%, and its effective components are 25-35% eucalyptol, 18-25% borneol, 10-15% linalool, 8-12% artemisinin, and the remainder are natural associated components of Artemisia argyi essential oil; the dual initiators are composed of dicyclohexyl peroxide and dicumyl peroxide at a mass ratio of 1:1-2, and the total mass fraction in the grafting reaction solution is 0.8-1.5%.

[0010] Further, the modal fiber is a far-infrared heating modal fiber, prepared as follows: bleached softwood pulp with an α-cellulose content ≥92% and a degree of polymerization of 800-1000 is used as raw material. An 8-12% (w / w) sodium hydroxide solution is added, and the mixture is stirred and dissolved for 3-5 hours at 25-35℃ and 200-300 r / min to prepare a spinning solution with a solid content of 18-22%. A far-infrared functional modification system is added to the spinning solution, with the mass ratio of each component to the spinning solution being: zirconium dioxide-titanium dioxide composite far-infrared ceramic powder: silane coupling agent KH-550: acrylate monomer: ammonium persulfate: spinning solution = 10-15: 2-3: 8-10: 0.5-1: 100. The particle size of the zirconium dioxide-titanium dioxide composite far-infrared ceramic powder is 50-100 nm, and the acrylate monomer is methyl methacrylate and butyl acrylate in a mass ratio of 3:2. The mixture was placed under a nitrogen atmosphere and stirred at a constant temperature of 40–50°C and 150–200 r / min for 30–40 min. After filtration with a precision of 5–10 μm and vacuum degassing at -0.09–-0.095 MPa for 1–2 h, the mixture was then subjected to wet spinning, step-by-step stretching, and post-treatment to obtain the far-infrared heating modal fiber.

[0011] Further, the wet spinning process parameters are as follows: spinning temperature 40-45℃, coagulation bath is 8-12% sodium hydroxide aqueous solution, bath temperature 20-25℃, spinning speed 50-80m / min; the stretching is a step-by-step stretching with a total multiple of 4-5 times, namely, water bath stretching at 60-70℃ for 2-2.5 times, and dry heat stretching at 120-140℃ for 1.8-2 times; the post-treatment is washing with water to neutral, oiling, and heat setting at 100-120℃.

[0012] Furthermore, the wear-resistant polyester yarn has a core-sheath structure, comprising a polyester yarn core and a wear-resistant yarn spirally wound on the polyester yarn core. The polyester yarn core is composed of multiple polyester networks combined together, and the wear-resistant yarn is polyethylene yarn with a fineness of 75-100D.

[0013] Furthermore, the polyester yarn core comprises moisture-absorbing and heat-generating polyester with a fineness of 30-50D and high-elastic polyester with a fineness of 20-30D.

[0014] Furthermore, the preparation process steps of the moisture-absorbing and heat-generating polyester are as follows: 1) Raw material ratio: The molar ratio is terephthalic acid: ethylene glycol: polyethylene glycol: adipic acid: aminohexanoic acid = 1:1.21.8:0.1~0.3:0.08~0.15:0.05~0.1 for material preparation; 2) Preparation of modified composite exothermic powder: Nano-calcium carbonate with a particle size of 30-80 nm and calcium oxide with a particle size of 50-100 nm are mixed at a mass ratio of 2-3:1. 2-4% of the total mass of the composite exothermic powder is added with silane coupling agent KH-560. The mixture is prepared by high-speed mixing at 1000-1500 r / min for 10-15 min. The amount added is 3-8% of the mass of terephthalic acid. 3) Esterification reaction: The raw material from step 1) is added to the reactor along with 0.02-0.05 wt% of catalyst and 0.01-0.03 wt% of stabilizer triphenyl phosphate. The catalyst is antimony trioxide or antimony glycolate. The mixture is stirred at 80-120 r / min under a nitrogen atmosphere, at a pressure of 0.2-0.3 MPa, and at a temperature of 240-260°C until the water distillation rate reaches more than 95%. 4) Polycondensation reaction: Cool to 230-240℃ and add the modified composite exothermic powder from step 2). Vacuum the mixture to an absolute pressure ≤100Pa, heat to 270-285℃ and stir at 50-80r / min for 60-90min to obtain polyester chips. 5) Spinning and stretching: The polyester chips are dried at 160-180℃ for 4-6 hours and then melt-spun, stretched and dried to obtain the moisture-absorbing and heat-generating polyester (411).

[0015] Compared with the prior art, the advantages of the present invention are as follows: (1) The surface of the fabric of this application is highly wear-resistant and anti-pilling, with excellent durability: the wear-resistant polyester yarn adopts a core-sheath structure design, and the sheath layer polyethylene yarn is spirally wound to tightly wrap the polyester yarn core, which has significant wear resistance and solves the problems of poor wear resistance and easy pilling of existing fabrics.

[0016] (2) The fabric of this application has natural long-lasting antibacterial properties and good skin-friendliness: antibacterial cotton fiber is the core of the fabric's long-lasting antibacterial effect. Combined with the auxiliary antibacterial effect of zirconium dioxide-titanium dioxide composite powder in far-infrared heating modal fiber, the antibacterial rate is still over 95% after 50 washes.

[0017] (3) It adopts a 24G double-sided circular knitting machine and a six-way loop forming system. Through precise control of the length of each weaving thread, the tight combination and functional synergy of each layer structure are achieved.

[0018] (4) The fabric layers of this application are stably connected. The inner and outer layers are tightly woven together by spandex filaments to form a whole. The weft knitting air layer structure is adopted. The upper and lower layers of the fabric are tightly connected by the shrinkage effect of the spandex in the connecting layer, so that the fabric layers are not easy to separate or wrinkle. It is more durable than traditional composite fabrics. The weft knitting air layer structure does not damage the performance of the functional yarns of each layer, and achieves a perfect balance between the stability and functionality of the fabric structure. Attached Figure Description

[0019] Figure 1 This is a knitting structure diagram of the knitted fabric in an embodiment of the present invention; Figure 2 This is a structural diagram of the knitted fabric in an embodiment of the present invention; Figure 3 This is a structural diagram of the wear-resistant polyester yarn in an embodiment of the present invention; In the diagram, 1 is the inner insulating layer, 2 is the connecting layer, 3 is the abrasion-resistant outer layer, 4 is the abrasion-resistant polyester yarn, 41 is the polyester yarn core, and 42 is the abrasion-resistant yarn. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings. The embodiments described are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. Example 1

[0021] like Figure 2 As shown, the skin-friendly and warm knitted fabric includes a warm inner layer 1, a connecting layer 2, and a wear-resistant outer layer 3, which are integrated and connected by a weft-knitted air layer structure. The warm inner layer 1 is woven from cotton / modal fiber blended yarn, the connecting layer 2 is woven from spandex filament, and the wear-resistant outer layer 3 is woven from wear-resistant composite yarn 4.

[0022] In this embodiment, the cotton / modal fiber blended yarn of the inner thermal layer 1 has an English count of 40S, and the ratio of cotton fiber to modal fiber in the blended yarn is 1:1. The spandex filament of the connecting layer 2 has a fineness of 35D.

[0023] The wear-resistant composite yarn 4 of the wear-resistant surface layer 3 has a core-sheath structure, including a polyester yarn core 41 and a wear-resistant yarn 42 spirally wound on the outside of the polyester yarn core 41. The polyester yarn core 41 is a yarn made of a 30D fine moisture-absorbing and heat-generating polyester and a 20D fine high-elastic polyester network combined together; the wear-resistant yarn 42 is a 100D fine polyethylene yarn.

[0024] like Figure 1 As shown, the fabric is woven on a 24G double-sided circular knitting machine. The six-way loop system of the weft-knitted air layer structure is knitted by the upper needle cylinder and the lower needle bed needles. The first and fourth knittings form the connecting layer 2, with the spandex filament knitting yarn length being 9cm / 100 stitches; the second and fifth knittings form the warm inner layer 1, with the blended yarn knitting yarn length being 22cm / 100 stitches; the third and sixth knittings form the abrasion-resistant outer layer 3, with the abrasion-resistant composite yarn 4 knitting yarn length being 24cm / 100 stitches.

[0025] The fabric is warm, highly elastic, wrinkle-resistant, and resistant to friction and pilling. The weft-knitted air layer structure of the fabric allows the spandex filaments in the middle to tightly bond the warm inner layer and the wear-resistant outer layer, and also allows the two layers to complement each other's functions, achieving a dual effect of warmth and windproof temperature locking, while also providing a comprehensive wearing effect of wear resistance, high elasticity, skin-friendly, and warmth.

[0026] The cotton fibers used in the blended yarn for the inner thermal layer are antibacterial cotton fibers. The preparation process is as follows: cotton fibers are mixed with deionized water at a mass ratio of 1:10 and soaked for 100 minutes, then dried at 55℃ to a moisture content of 7%. Activation is performed using 40W helium plasma with a discharge gap of 2.5 mm for 60 seconds. A grafting reaction solution is prepared, with anhydrous ethanol:deionized water = 7.5:2.5 (volume ratio). 5% of Artemisia argyi essential oil (extraction rate 0.9%, eucalyptol 30%, borneol 22%, linalool 12%, artemisia argyi ketone 10%) is added, along with 1.2% of a dual initiator (dicyclohexyl peroxide: dicumyl peroxide = 1:1.5). The activated cotton fibers are mixed with the grafting reaction solution at a mass ratio of 1:15, stirred at 35℃ and 65 r / min for 2 hours, washed four times with anhydrous ethanol, and vacuum dried at 65℃ to constant weight to obtain antibacterial cotton fibers.

[0027] Helium plasma activation can form a large number of active groups on the surface of cotton fibers, which greatly improves the grafting efficiency of cotton fibers and artemisia oil. Compared with traditional chemical modification processes, plasma activation leaves no chemical reagent residues and causes little damage to the mechanical properties of cotton fibers, effectively preserving the skin-friendly, breathable and soft characteristics of cotton fibers.

[0028] The dual initiator system can synergistically enhance the grafting reaction rate and grafting strength, enabling mugwort essential oil to be stably and covalently bonded to cotton fibers, fundamentally solving the technical pain point of natural essential oils easily falling off and improving antibacterial long-lasting effect.

[0029] The setting of helium plasma activation parameters is based on the balance between the generation efficiency of active groups on the surface of cotton fibers and their mechanical properties. Too long an activation time will lead to a decrease in the strength of cotton fibers, while too short an activation time will result in insufficient grafting efficiency.

[0030] The modal fiber used in the blended yarn for the inner thermal layer is far-infrared heating modal fiber. The preparation process is as follows: bleached softwood pulp with 93% α-cellulose content and a degree of polymerization of 900 is selected as raw material. A 10% sodium hydroxide solution is added, and the mixture is stirred and dissolved for 4 hours at 30℃ and 250 r / min to prepare a spinning solution with a solid content of 20%. The spinning solution is prepared with a mass ratio of zirconium dioxide-titanium dioxide composite far-infrared ceramic powder: silane coupling agent KH-550: acrylate monomer: ammonium persulfate: spinning solution = 12:2.5:9:0.8:100. Zirconium dioxide-titanium dioxide composite far-infrared ceramic powder with a particle size of 80 nm, silane coupling agent KH-550, acrylate monomer (methyl methacrylate: butyl acrylate = 3:2), and ammonium persulfate are added to the spinning solution. The mixture is then placed under a nitrogen atmosphere at 45℃ and 180 r / min. Under constant temperature stirring conditions for 35 min, the fibers were filtered with an 8 μm precision and then degassed under vacuum at -0.092 MPa for 1.5 h. Subsequently, wet spinning was performed with a spinneret orifice diameter of 0.10 mm, an aspect ratio of 4:1, a spinning temperature of 42 °C, a coagulation bath of 10% sodium hydroxide aqueous solution at 22 °C, a spinning speed of 65 m / min, and a spinning bath distance of 10 cm. The nascent fibers were initially washed with deionized water at 35 °C for 1.5 min. After spinning, the fibers underwent stepwise stretching: first, a 2.2-fold stretch in a 65 °C water bath (stretching speed 120 m / min), followed by a 1.9-fold dry heat stretch at 130 °C, for a total stretching ratio of 4.1 times. Finally, the fibers were subjected to multi-stage water washing at 40 °C, 50 °C, and 60 °C for 6 min until pH=7.0, then oiled with an anionic polyester oiling agent (oiling rate 1.0%), and heat-set with hot air at 110 °C for 4 min to obtain far-infrared heating modal fibers.

[0031] Silane coupling agent KH-550 can modify the surface of far-infrared ceramic powder by introducing active groups on the powder surface, improving the dispersibility and compatibility of ceramic powder in spinning solution, and avoiding uneven heating performance caused by powder agglomeration; acrylate monomers can enhance the bonding force between ceramic powder and modal fiber matrix, prevent ceramic powder from falling off during spinning and use, and improve the long-term performance of far-infrared heating.

[0032] The preparation process of the moisture-absorbing and heat-generating polyester in polyester yarn core 41 is as follows: I. Raw material preparation: Prepare raw materials in a molar ratio of 1:1.5:0.22:0.11:0.07 (terephthalic acid: ethylene glycol: polyethylene glycol: adipic acid: aminohexanoic acid), with polyethylene glycol having a number average molecular weight of 3000 and a molecular weight distribution index of 1.15; II. Preparation of modified composite exothermic powder: 50nm nano-calcium carbonate and 70nm calcium oxide were mixed at a ratio of 2.5:1, and 3% silane coupling agent KH-560 was added. The mixture was then mixed at 1200r / min for 12min. The amount of powder added was 5% of the mass of terephthalic acid. III. Esterification reaction: Add 0.03wt% antimony trioxide and 0.02wt% triphenyl phosphate, and stir at 100r / min under a nitrogen atmosphere and at 0.25MPa and 250℃ until the water distillation rate is 95%; IV. Polycondensation reaction: Cool to 235℃, add powder, vacuum to 80Pa, heat to 275℃, and react for 75 minutes at a stirring speed of 65r / min to obtain modified polyester chips. V. After drying the modified polyester chips at 170℃ for 5 hours, melt-spin, stretch, and dry them to obtain moisture-absorbing and heat-generating polyester.

[0033] Polyethylene glycol, adipic acid, and aminocaproic acid can introduce a large number of hydrophilic groups into the polyester molecular chain, significantly improving the moisture absorption performance of the fiber and providing a basis for moisture absorption and heat release. Nano-calcium carbonate and calcium oxide composites can form a synergistic heat release effect, improving the moisture absorption and heat release efficiency of the powder. Silane coupling agent KH-560 can improve the dispersibility of the powder in the polyester matrix and prevent powder agglomeration. The synergistic effect of hydrophilic groups and composite heat-generating powders achieves efficient moisture absorption and passive heat generation, with a temperature rise much higher than that of ordinary moisture-absorbing and heat-generating polyester, and the fiber has excellent mechanical properties, meeting the needs of fabric weaving and use.

[0034] Comparative Example 1: The only difference from Example 1 is that the antibacterial cotton fiber is replaced with ordinary cotton fiber; all other processes and parameters are the same as in Example 1. Comparative Example 2: The only difference from Example 1 is that the far-infrared heating modal fiber is replaced with ordinary modal fiber, while the rest of the process and parameters are the same as in Example 1.

[0035] Comparative Example 3: The only difference from Example 1 is that the moisture-absorbing and heat-generating polyester is replaced with ordinary polyester; all other processes and parameters are the same as in Example 1.

[0036] Performance testing The fabrics of Example 1 and Comparative Examples 1-3 were subjected to 50 household washes according to GB / T 8629, and then their various properties were tested according to the corresponding national standards. The antibacterial properties were tested according to GB / T 20944.3-2008, the far-infrared heating properties were tested according to GB / T30127-2013, and the moisture absorption and heat generation properties were tested according to GB / T 29866-2013. The test results are shown in Table 1.

[0037] Table 1. Test data for the examples and comparative examples.

[0038] As shown in Table 1, after 50 washes, the fabric of this invention exhibits an antibacterial rate of over 98% against Staphylococcus aureus and Escherichia coli, a far-infrared radiation temperature rise of 2.6℃, and an average temperature rise of 4.3℃ after 30 minutes of moisture absorption and heat generation. All performance characteristics far exceed national standards (antibacterial rate ≥70%, far-infrared temperature rise ≥1.4℃, moisture absorption temperature rise ≥3℃). In Comparative Example 1, the antibacterial rate decreased significantly due to the replacement with ordinary cotton fiber, indicating that antibacterial cotton fiber is the core of the fabric's long-lasting antibacterial effect. In Comparative Example 2, the far-infrared temperature rise was only 0.5℃ due to the replacement with ordinary modal fiber, indicating that far-infrared modal fiber determines the fabric's far-infrared heating performance. In Comparative Example 3, the moisture absorption temperature rise was only 0.8℃ due to the replacement with ordinary polyester, indicating that moisture-absorbing polyester is the key to the fabric's moisture absorption and heat generation.

Claims

1. A skin-friendly and warm knitted fabric, characterized in that: The product includes an inner heat-insulating layer (1), a connecting layer (2), and an outer wear-resistant layer (3). The inner heat-insulating layer (1), the connecting layer (2), and the outer wear-resistant layer (3) are woven into a weft-knitted air layer structure. The weft-knitted air layer structure includes a six-way loop system. The first and fourth loops of the six-way loop system form the connecting layer (2), the second and fifth loops form the inner heat-insulating layer (1), and the third and sixth loop systems form the outer wear-resistant layer (3). The yarn used for the inner heat-insulating layer (1) is a blend of cotton fiber and modal fiber. The yarn used for the connecting layer (2) is spandex filament. The yarn used for the outer wear-resistant layer (3) is a wear-resistant composite yarn.

2. The skin-friendly and warm knitted fabric according to claim 1, characterized in that: The yarn blend of cotton and modal fibers has a count of 40–60S and a yarn length of 20–24 cm / 100 stitches; the spandex filament has a fineness of 20–35D and a yarn length of 8–10 cm / 100 stitches; the abrasion-resistant composite yarn has a yarn length of 22–26 cm / 100 stitches.

3. The skin-friendly and warm knitted fabric according to claim 1, characterized in that: The cotton fiber is an antibacterial cotton fiber. The preparation process is as follows: the cotton fiber is soaked in deionized water for 80-120 min, dried at 50-60℃ to a water content of 6-8%, and then activated with 30-45W helium plasma at a discharge gap of 2-3 mm for 40-75 s; then the activated cotton fiber is immersed in the grafting reaction solution and stirred at 50-80 r / min for 1-3 h, washed with anhydrous ethanol 3-5 times, and vacuum dried at 60-70℃ to constant weight. The mass ratio of cotton fiber to deionized water is 1:6-15, the mass ratio of cotton fiber to grafting reaction solution is 1:10-20, and the reaction temperature is 30-40℃.

4. The skin-friendly and warm knitted fabric according to claim 3, characterized in that, The grafting reaction solution is a composite system of Artemisia argyi essential oil and dual initiators. The solvent is a mixture of anhydrous ethanol and deionized water at a volume ratio of 7-8:2-3. The Artemisia argyi essential oil has a mass fraction of 3-8% in the grafting reaction solution, and its active ingredients are 25-35% eucalyptol, 18-25% borneol, 10-15% linalool, and 8-12% artemisinin, with the remainder being natural byproducts of Artemisia argyi essential oil. The dual initiators are composed of dicyclohexyl peroxide and dicumyl peroxide at a mass ratio of 1:1-2, and their total mass fraction in the grafting reaction solution is 0.8-1.5%.

5. The skin-friendly and warm knitted fabric according to claim 1, characterized in that: The modal fiber is a far-infrared heating modal fiber. The preparation process is as follows: bleached softwood pulp with an α-cellulose content ≥92% and a degree of polymerization of 800-1000 is used as raw material. An 8-12% (w / w) sodium hydroxide solution is added, and the mixture is stirred and dissolved for 3-5 hours at 25-35℃ and 200-300 r / min to prepare a spinning solution with a solid content of 18-22%. A far-infrared functional modification system is added to the spinning solution. The mass ratio of each component to the spinning solution is: zirconium dioxide-titanium dioxide composite far-infrared ceramic powder: silane coupling agent KH-550: acrylate monomer: ammonium persulfate: spinning solution = 10-15: 2-3: 8-10: 0.5-1:

100. The particle size of the zirconium dioxide-titanium dioxide composite far-infrared ceramic powder is 50-100 nm, and the acrylate monomer is methyl methacrylate and butyl acrylate in a mass ratio of 3:

2. The mixture was placed under a nitrogen atmosphere and stirred at a constant temperature of 40–50°C and 150–200 r / min for 30–40 min. After filtration with a precision of 5–10 μm and vacuum degassing at -0.09–-0.095 MPa for 1–2 h, the mixture was then subjected to wet spinning, step-by-step stretching, and post-treatment to obtain the far-infrared heating modal fiber.

6. The skin-friendly and warm knitted fabric according to claim 5, characterized in that, The wet spinning process parameters are as follows: spinning temperature 40-45℃, coagulation bath is 8-12% sodium hydroxide aqueous solution with a bath temperature of 20-25℃, and spinning speed 50-80m / min; the stretching is a step-by-step stretching with a total multiple of 4-5 times, namely, water bath stretching at 60-70℃ for 2-2.5 times and dry heat stretching at 120-140℃ for 1.8-2 times; the post-treatment is washing with water until neutral, oiling, and heat setting at 100-120℃.

7. The skin-friendly and warm knitted fabric according to claim 1, characterized in that: The wear-resistant composite yarn (4) has a core-sheath structure, including a polyester yarn core (41) and a wear-resistant yarn (42) spirally wound on the polyester yarn core. The polyester yarn core (41) is composed of multiple polyester networks combined together, and the wear-resistant yarn (42) is polyethylene yarn with a fineness of 75-100D.

8. The skin-friendly and warm knitted fabric according to claim 7, characterized in that: The polyester yarn core (41) includes moisture-absorbing and heat-generating polyester with a fineness of 30-50D and high-elastic polyester with a fineness of 20-30D.

9. The skin-friendly and warm knitted fabric according to claim 8, characterized in that: The preparation process steps of the moisture-absorbing and heat-generating polyester are as follows: 1) Raw material ratio: The molar ratio is terephthalic acid: ethylene glycol: polyethylene glycol: adipic acid: aminohexanoic acid = 1:1.21.8:0.1~0.3:0.08~0.15:0.05~0.1 for material preparation; 2) Preparation of modified composite exothermic powder: Nano-calcium carbonate with a particle size of 30-80 nm and calcium oxide with a particle size of 50-100 nm are mixed at a mass ratio of 2-3:

1. 2-4% of the total mass of the composite exothermic powder is added with silane coupling agent KH-560. The mixture is prepared by high-speed mixing at 1000-1500 r / min for 10-15 min. The amount added is 3-8% of the mass of terephthalic acid. 3) Esterification reaction: The raw material from step 1) is added to the reactor along with 0.02-0.05 wt% of catalyst and 0.01-0.03 wt% of stabilizer triphenyl phosphate. The catalyst is antimony trioxide or antimony glycolate. The mixture is stirred at 80-120 r / min under a nitrogen atmosphere, at a pressure of 0.2-0.3 MPa, and at a temperature of 240-260°C until the water distillation rate reaches more than 95%. 4) Polycondensation reaction: Cool to 230-240℃ and add the modified composite exothermic powder from step 2). Vacuum the mixture to an absolute pressure ≤100Pa, heat to 270-285℃ and stir at 50-80r / min for 60-90min to obtain polyester chips. 5) Spinning and stretching: The polyester chips are dried at 160-180℃ for 4-6 hours and then melt-spun, followed by stretching and drying to obtain the moisture-absorbing and heat-generating polyester.

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