A long-staple cotton knitted fabric and a method for manufacturing the same

Abstract

This invention relates to the field of fabric technology, specifically to a long-staple cotton knitted fabric and its preparation method. The fabric comprises a long-staple cotton knitted base fabric and a hydrophilic moisture-wicking layer fixed to the outer surface of its cotton fibers. It is obtained by padding, pre-drying, baking, washing, and drying 1000 parts of pre-treated and dried long-staple cotton knitted greige fabric and 4800-5900 parts of a low-moisture-content, time-controlled grafting finishing solution. The finishing solution contains specific components such as anhydrous dimethyl sulfoxide, anhydrous lithium chloride, and isocyanate-terminated carboxyl betaine polymer, with a water content of 100-300 mg / kg. This invention achieves a balance of rapid moisture absorption and wicking, quick drying, low wet adhesion, and basic mechanical properties simultaneously without clogging capillary channels, resulting in excellent overall performance through synergistic control of the grafting reaction and process parameters.

Description

Technical Field

[0001] This invention relates to the field of fabric technology, and in particular to a long-staple cotton knitted fabric and its preparation method. Background Technology

[0002] Egyptian long-staple cotton, due to its fine, long fibers, high strength, and soft, skin-friendly properties, is widely used in the production of high-end close-fitting knitted fabrics. In particular, double-sided weft-knitted fabrics woven from 100% Egyptian long-staple cotton combed, tightly spun yarn have an average fiber length of no less than 34mm, with yarn specifications mostly at 60S / 2, a weight of approximately 160g / m², and a fabric density of 120 loops / 10cm in the longitudinal direction and 90 loops / 10cm in the transverse direction. Naturally, it possesses superior breathability and feel compared to ordinary cotton, making it an ideal base material for producing high-quality close-fitting garments. However, the natural hydrophilic properties of Egyptian long-staple cotton still have inherent limitations: when the body sweats, although its fibers can quickly absorb sweat, the rate of moisture transfer between fibers and within the fabric is insufficient, easily leading to sweat accumulation at the skin-fabric contact surface, causing a stuffy, sticky, and uncomfortable feeling. Furthermore, after repeated washing, the natural waxy layer on the fiber surface gradually peels off, further reducing its moisture absorption and wicking properties.

[0003] To address this deficiency, the industry has developed various approaches to hydrophilic finishing techniques for cotton knitted fabrics, including ordinary hydrophilic finishing, polyether-based hydrophilic softening finishing, simple coating-type moisture-wicking finishing, and general cotton fabric grafting moisture-wicking finishing. Conventional hydrophilic finishing, which involves coating the fabric surface with small-molecule hydrophilic agents, can shorten the initial water diffusion time to some extent. However, the hydrophilic agents have weak bonding with fibers, making them easy to detach after washing and resulting in insufficient durability. Polyether-based hydrophilic softening finishing can improve hand feel while enhancing hydrophilicity, but polyether segments tend to migrate into the fiber interior, causing the surface moisture-wicking effect to decrease over time. Simple coating-type moisture-wicking finishing relies on physical adsorption to form a moisture-wicking layer, which can easily cause blockage of capillary channels between fabric loops, reducing air permeability and tensile strength. Grafting moisture-wicking finishing of general cotton fabrics introduces hydrophilic groups through chemical reactions, but existing grafting systems mostly use aqueous finishing solutions, and reaction end groups such as isocyanates are easily consumed by moisture in advance. Grafting efficiency and distribution uniformity are difficult to control, and the grafted layer tends to over-cover the fiber surface, destroying the original soft touch and breathable structure of Egyptian long-staple cotton.

[0004] The aforementioned existing technologies have failed to develop suitable finishing solutions for the unique structural characteristics of Egyptian long-staple cotton knitted fabrics. They cannot simultaneously ensure the surface fixation stability of the hydrophilic moisture-wicking layer, maintain the original capillary channels of the fabric, achieve low wet adhesion, and maintain basic mechanical properties. As a result, the wet comfort and durability of high-end Egyptian long-staple cotton knitted fabrics cannot meet the ever-increasing demands of consumers, thus limiting their application expansion in the high-end intimate apparel sector. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a long-staple cotton knitted fabric and its preparation method, so as to solve the problem that the existing hydrophilic finishing of cotton knitted fabrics is difficult to simultaneously achieve surface fixation stability, retention of capillary channels between loops, low adhesion in wet state and strength retention, resulting in poor wet comfort.

[0006] To achieve the above objectives, the present invention provides a long-staple cotton knitted fabric, comprising a long-staple cotton knitted base fabric and a hydrophilic moisture-wicking layer fixed to the outer surface of cotton fibers of the long-staple cotton knitted base fabric. By weight, the long-staple cotton knitted fabric is obtained by impregnating 1000 parts of pretreated and dried long-staple cotton knitted greige fabric and 4800-5900 parts of low-moisture-content time-controlled grafting finishing solution with two dips and two nips, pre-drying, baking, washing and drying.

[0007] The low-moisture-content time-controlled grafting solution is prepared by mixing the following raw materials in the order listed: 450-600 parts anhydrous dimethyl sulfoxide, 12-18 parts anhydrous lithium chloride, 1300-1700 parts anhydrous N,N-dimethylformamide, 250-350 parts isocyanate-terminated carboxylic betaine polymer, 8-12 parts polyethylene glycol dimethyl ether 250, 20-30 parts polyethylene glycol dimethyl ether 500, 2800-3200 parts ultra-dry acetone, and 4-6 parts dibutyltin dilaurate;

[0008] The isocyanate-terminated carboxylic betaine polymer has a number average molecular weight of 4000-8000 and an isocyanate group mass fraction of 4‰-8‰.

[0009] The water content of the low-moisture-content time-controlled grafting solution is 2500-2800 mg / kg;

[0010] The padding is a two-dip, two-roll process with a roll-off rate of 60%-70%; the pre-drying is done in 50°C hot air until the fabric weight is 125%-130% of the dry fabric weight; the baking is done in 85°C-95°C hot air for 25-35 minutes.

[0011] Preferably, in the hydrophilic moisture-wicking layer, the isocyanate-terminated carboxybetaine polymer is fixed to the outer surface layer of the cotton fiber through a carbamate bond formed by the reaction of its isocyanate groups with the hydroxyl groups on the surface of the long-staple cotton fiber.

[0012] Preferably, the long-staple cotton knitted fabric is a double-sided weft-knitted fabric obtained by weaving 100% Egyptian long-staple cotton combed compact yarn on a double-sided circular weft machine; the yarn specification is 60S / 2, and the weight is 160g / m². 2 The fabric has a width of 180cm, an average fiber length of not less than 34mm, a longitudinal density of 120 loops / 10cm, and a transverse density of 90 loops / 10cm.

[0013] Preferably, the isocyanate-terminated carboxybetaine polymer is obtained by reacting a hydroxyl-terminated carboxybetaine polymer with isophorone diisocyanate; the hydroxyl-terminated carboxybetaine polymer is obtained by polymerizing 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate in the presence of 2-mercaptoethanol and 2,2′-azobisisobutyronitrile.

[0014] Preferably, the mass ratio of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, 2-mercaptoethanol and 2,2′-azobisisobutyronitrile in the raw materials for preparing the hydroxyl-terminated carboxybetaine polymer is 500:3-10:5.

[0015] Preferably, the mass ratio of hydroxyl-terminated carboxybetaine polymer to isophorone diisocyanate in the raw materials for preparing the isocyanate-terminated carboxybetaine polymer is 350:45-80.

[0016] Preferably, the hydroxyl-terminated carboxybetaine polymer has a number-average molecular weight of 3500-7800, a molecular weight distribution index of 1.6-2.2, and a terminal hydroxyl content of 125-240 μmol / g.

[0017] Preferably, the low-moisture-content time-controlled grafting finishing solution is used to treat the long-staple cotton knitted fabric within 30 minutes after the addition of the dibutyltin dilaurate.

[0018] Preferably, the moisture content of the ultra-dry acetone is less than 50 mg / kg.

[0019] This invention also provides a method for preparing long-staple cotton knitted fabric, characterized by comprising the following steps:

[0020] (1) Pre-treat, wash and dry the long-staple cotton knitted fabric to obtain the pre-treated fabric;

[0021] (2) Preparation of hydroxyl-terminated carboxylic betaine polymer;

[0022] (3) React the hydroxyl-terminated carboxy betaine polymer with isophorone diisocyanate to obtain isocyanate-terminated carboxy betaine polymer;

[0023] (4) Anhydrous dimethyl sulfoxide, anhydrous lithium chloride, anhydrous N,N-dimethylformamide, the isocyanate-terminated carboxy betaine polymer, polyethylene glycol dimethyl ether 250, polyethylene glycol dimethyl ether 500, ultra-dry acetone and dibutyltin dilaurate are mixed in sequence to obtain a low-water-content time-controlled grafting solution.

[0024] (5) The pretreated fabric is impregnated, dipped twice and rubbed twice, pre-dried and baked using the low moisture content time-controlled grafting finishing solution;

[0025] (6) Wash, dry and balance the baked fabric to obtain the long-staple cotton knitted fabric.

[0026] The beneficial effects of this invention are:

[0027] (1) The present invention uses isocyanate-terminated carboxy betaine polymer, which reacts with the hydroxyl groups on the surface of long-staple cotton fiber to form urethane bonds, thereby stably fixing the hydrophilic moisture-wicking layer to the outer surface of the fiber, solving the problem of weak binding force and easy washing and removal of ordinary hydrophilic agents.

[0028] (2) This invention achieves a balance of rapid moisture absorption and wicking, quick drying, low wet adhesion and basic mechanical properties by using the synergistic effect of low water content time-controlled grafting solution (water content 2500-2800 mg / kg), anhydrous lithium chloride / dipolyether time-controlled and pre-baking space control (fabric mass after pre-baking is 125%-130% of dry fabric, baking 85-95℃) without significantly blocking the capillary channels between the coils of long-staple cotton knitted fabric. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0030] Raw material source and model:

[0031] Egyptian long-staple cotton knitted fabric: This double-sided weft-knitted fabric is made from 100% Egyptian long-staple cotton combed compact yarn woven on a double-sided circular weft machine. The yarn specification is 60S / 2, and the weight is 160g / m². 2 The fabric width is 180cm, the average fiber length is not less than 34mm, the longitudinal density is 120 loops / 10cm, and the transverse density is 90 loops / 10cm; Polyethylene glycol dimethyl ether 250: Merck Sigma-Aldrich product, product code 814173.

[0032] Polyethylene glycol dimethyl ether 500: Merck Sigma-Aldrich product, product code 814171; Ultra-dry acetone: Thermo Fisher Scientific AcroSeal product, product code 326801000, moisture content less than 50 mg / kg.

[0033] Example 1:

[0034] Step 1: Take 1000g of Egyptian long-staple cotton knitted fabric, add 20000g of deionized water, 20g of sodium carbonate and 5g of sodium dodecyl sulfate, and treat at 50°C for 30min; after draining, add 20000g of deionized water and wash for 10min, then add another 20000g of deionized water and wash for another 10min; dry the washed fabric in 80°C hot air for 40min, then in 105°C hot air for 10min, calculate the fabric moisture content based on the weight difference before and after drying, ensuring the fabric moisture content is no higher than 0.3%, and then place it in a sealed drying bag for later use.

[0035] Step 2: Add 1500g of anhydrous dimethyl sulfoxide, 500g of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, 5g of 2-mercaptoethanol, and 5g of [other ingredients] to a dried reaction flask protected with nitrogen. 2,2′-Azobisisobutyronitrile (AIBN) was purged with nitrogen for 30 min and stirred at 65°C for 6 h. After the reaction, the reaction solution was added dropwise to 15000 g of ultra-dry acetone, filtered to obtain a precipitate, and then washed twice with 5000 g of ultra-dry acetone. The precipitate was dissolved in 5000 g of deionized water and dialyzed in 50000 g of deionized water for 24 h using a dialysis bag with a molecular weight cutoff of 1000 Da, with 50000 g of deionized water replaced every 6 h. The dialysate was freeze-dried for 24 h and then vacuum-dried at 40°C for 12 h to obtain a hydroxyl-terminated carboxybetaine polymer. Gel permeation chromatography showed that the number-average molecular weight of the obtained hydroxyl-terminated carboxybetaine polymer was 6500 and the molecular weight distribution index was 2. The end-group titration showed that the content of terminal hydroxyl groups was 150 μmol / g.

[0036] Step 3: Add 350g of the hydroxyl-terminated carboxylic betaine polymer obtained in Step 2 and 1750g of anhydrous dimethyl sulfoxide to a dried reaction flask protected by nitrogen. Stir at 40°C for 40 min. Then add 50g of isophorone diisocyanate and 3g of dibutyltin dilaurate. React at 45°C for 4 h. After the reaction is complete, add the reaction solution dropwise to 15000g of anhydrous ethyl acetate to precipitate. After filtration, wash the precipitate three times with 5000g of anhydrous ethyl acetate. Then dry under vacuum at 30°C for 8 h to obtain the isocyanate-terminated carboxylic betaine polymer. The number average molecular weight is 7000 as determined by gel permeation chromatography. The isocyanate group mass fraction is 6‰ as determined by di-n-butylamine back titration.

[0037] Step 4: Add 500g of anhydrous dimethyl sulfoxide and 15g of anhydrous lithium chloride (vacuum dried at 120°C for 4h) to a drying container, and stir at 40°C for 20min; add 1500g of anhydrous N,N-dimethylformamide, and continue stirring for 10min; add 300g of the isocyanate-terminated carboxyl betaine polymer obtained in Step 3, and stir at 40°C for 30min; after cooling the system to 25°C, add 10g of polyethylene glycol dimethyl ether 250 (dried at 4A molecular sieve for 24h), and stir for 5min. Add 25g of polyethylene glycol dimethyl ether 500 dried for 24 hours using 4A molecular sieves, and stir for 8 minutes; add 3000g of ultra-dry acetone and stir for 10 minutes; filter through a 100μm PTFE filter; finally add 5g of dibutyltin dilaurate and stir for 3 minutes to obtain 5355g of low-water-content time-controlled grafting finishing solution; the water content of the finishing solution was determined to be 225mg / kg using the Karl Fischer method, and the finishing solution should be used within 30 minutes after the addition of dibutyltin dilaurate.

[0038] Step 5: Immerse 1000g of Egyptian long-staple cotton knitted fabric obtained in Step 1 into 5300g of low moisture content time-controlled grafting finishing solution obtained in Step 4. After immersion for 3 minutes, perform two dips and two nips. Calculate the nip-out rate based on the difference between the quality of the fabric after nipping and the quality of the dry fabric, so that the nip-out rate is 65%. Pre-dry the fabric after nipping in hot air at 50°C until the fabric weight is 1280g, and then bake it in hot air at 90°C for 30 minutes.

[0039] Step Six: Add the fabric dried in Step Five to a washing solution consisting of 20,000g deionized water, 100g ethanol, and 40g sodium bicarbonate, and wash at 40°C for 15 minutes; after draining, add 20,000g deionized water and wash for 10 minutes, then add another 20,000g deionized water and wash for 10 minutes, and finally add another 20,000g deionized water and wash for 10 minutes; dry the washed fabric in hot air at 70°C for 30 minutes, and then equilibrate in an environment with a temperature of 20°C and a relative humidity of 65% for 24 hours to obtain long-staple cotton knitted fabric.

[0040] Example 2:

[0041] Step 1: Take 1000g of Egyptian long-staple cotton knitted fabric, add 20000g of deionized water, 20g of sodium carbonate and 5g of sodium dodecyl sulfate, and treat at 50°C for 30min; after draining, add 20000g of deionized water and wash for 10min, then add another 20000g of deionized water and wash for another 10min; dry the washed fabric in 80°C hot air for 40min, then in 105°C hot air for 10min, calculate the fabric moisture content based on the weight difference before and after drying, ensuring the fabric moisture content is no higher than 0.3%, and then place it in a sealed drying bag for later use.

[0042] Step 2: Add 1500g of anhydrous dimethyl sulfoxide, 500g of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, 10g of 2-mercaptoethanol, and 5g of [other ingredients] to a dried reaction flask protected with nitrogen. 2,2′-Azobisisobutyronitrile (AIBN) was purged with nitrogen for 30 min and stirred at 65°C for 6 h. After the reaction, the reaction solution was added dropwise to 15000 g of ultra-dry acetone, filtered to obtain a precipitate, and then washed twice with 5000 g of ultra-dry acetone. The precipitate was dissolved in 5000 g of deionized water and dialyzed in 50000 g of deionized water for 24 h using a dialysis bag with a molecular weight cutoff of 1000 Da, with 50000 g of deionized water replaced every 6 h. The dialysate was freeze-dried for 24 h and then vacuum-dried at 40°C for 12 h to obtain a hydroxyl-terminated carboxybetaine polymer. Gel permeation chromatography showed that the number-average molecular weight of the obtained hydroxyl-terminated carboxybetaine polymer was 3500 and the molecular weight distribution index was 2. The end-group titration showed that the content of terminal hydroxyl groups was 240 μmol / g.

[0043] Step 3: Add 350g of the hydroxyl-terminated carboxylic betaine polymer obtained in Step 2 and 1750g of anhydrous dimethyl sulfoxide to a dried reaction flask protected by nitrogen. Stir at 40°C for 40 min. Then add 80g of isophorone diisocyanate and 4g of dibutyltin dilaurate. React at 45°C for 4 h. After the reaction is complete, add the reaction solution dropwise to 15000g of anhydrous ethyl acetate to precipitate. After filtration, wash the precipitate three times with 5000g of anhydrous ethyl acetate. Then dry under vacuum at 30°C for 8 h to obtain the isocyanate-terminated carboxylic betaine polymer. The number average molecular weight is 4000 as determined by gel permeation chromatography. The isocyanate group mass fraction is 8‰ as determined by di-n-butylamine back titration.

[0044] Step 4: Add 450g of anhydrous dimethyl sulfoxide and 12g of anhydrous lithium chloride (vacuum dried at 120°C for 4 hours) to a drying container, and stir at 40°C for 20 minutes; add 1300g of anhydrous N,N-dimethylformamide, and continue stirring for 10 minutes; add 250g of the isocyanate-terminated carboxyl betaine polymer obtained in Step 3, and stir at 40°C for 30 minutes; after cooling the system to 25°C, add 8g of polyethylene glycol dimethyl ether 250 (dried for 24 hours using 4A molecular sieves), and stir for 5 minutes. Add 20g of polyethylene glycol dimethyl ether 500 dried for 24 hours using 4A molecular sieves, and stir for 8 minutes; add 2800g of ultra-dry acetone and stir for 10 minutes; filter through a 100μm PTFE filter; finally add 4g of dibutyltin dilaurate and stir for 3 minutes to obtain 4844g of low-water-content time-controlled grafting finishing solution; the water content of the finishing solution was determined to be 185mg / kg using the Karl Fischer method, and the finishing solution was used within 30 minutes after the addition of dibutyltin dilaurate.

[0045] Step 5: Immerse 1000g of Egyptian long-staple cotton knitted fabric obtained in Step 1 into 4800g of low-moisture-content time-controlled grafting finishing solution obtained in Step 4. After immersion for 2 minutes, perform two dips and two nips. Calculate the nip-out rate based on the difference between the fabric weight after nipping and the dry fabric weight, so that the nip-out rate is 60%. Pre-dry the fabric after nipping in hot air at 50°C until the fabric weight is 1250g, and then bake it in hot air at 85°C for 35 minutes.

[0046] Step Six: Add the fabric dried in Step Five to a washing solution consisting of 20,000g deionized water, 100g ethanol, and 40g sodium bicarbonate, and wash at 40°C for 15 minutes; after draining, add 20,000g deionized water and wash for 10 minutes, then add another 20,000g deionized water and wash for 10 minutes, and finally add another 20,000g deionized water and wash for 10 minutes; dry the washed fabric in hot air at 70°C for 30 minutes, and then equilibrate in an environment with a temperature of 20°C and a relative humidity of 65% for 24 hours to obtain long-staple cotton knitted fabric.

[0047] Example 3:

[0048] Step 1: Take 1000g of Egyptian long-staple cotton knitted fabric, add 20000g of deionized water, 20g of sodium carbonate and 5g of sodium dodecyl sulfate, and treat at 50°C for 30min; after draining, add 20000g of deionized water and wash for 10min, then add another 20000g of deionized water and wash for another 10min; dry the washed fabric in 80°C hot air for 40min, then in 105°C hot air for 10min, calculate the fabric moisture content based on the weight difference before and after drying, ensuring the fabric moisture content is no higher than 0.3%, and then place it in a sealed drying bag for later use.

[0049] Step 2: Add 1500g of anhydrous dimethyl sulfoxide, 500g of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, 3g of 2-mercaptoethanol, and 5g of [other ingredients] to a dried reaction flask protected with nitrogen. 2,2′-Azobisisobutyronitrile (AIBN) was purged with nitrogen for 30 min and stirred at 65°C for 6 h. After the reaction, the reaction solution was added dropwise to 15000 g of ultra-dry acetone, filtered to obtain a precipitate, and then washed twice with 5000 g of ultra-dry acetone. The precipitate was dissolved in 5000 g of deionized water and dialyzed in 50000 g of deionized water for 24 h using a dialysis bag with a molecular weight cutoff of 1000 Da, with 50000 g of deionized water replaced every 6 h. The dialysate was freeze-dried for 24 h and then vacuum-dried at 40°C for 12 h to obtain a hydroxyl-terminated carboxybetaine polymer. Gel permeation chromatography showed that the number-average molecular weight of the obtained hydroxyl-terminated carboxybetaine polymer was 7800 and the molecular weight distribution index was 2. The end-group titration showed that the content of terminal hydroxyl groups was 125 μmol / g.

[0050] Step 3: Add 350g of the hydroxyl-terminated carboxylic betaine polymer obtained in Step 2 and 1750g of anhydrous dimethyl sulfoxide to a dried reaction flask protected with nitrogen. Stir at 40°C for 40 min. Then add 45g of isophorone diisocyanate and 3g of dibutyltin dilaurate. React at 45°C for 4 h. After the reaction is complete, add the reaction solution dropwise to 15000g of anhydrous ethyl acetate to precipitate. After filtration, wash the precipitate three times with 5000g of anhydrous ethyl acetate. Then dry under vacuum at 30°C for 8 h to obtain the isocyanate-terminated carboxylic betaine polymer. The number average molecular weight is 8000 as determined by gel permeation chromatography. The isocyanate group mass fraction is 4‰ as determined by di-n-butylamine back titration.

[0051] Step 4: Add 600g of anhydrous dimethyl sulfoxide and 18g of anhydrous lithium chloride (vacuum dried at 120°C for 4 hours) to a drying container, and stir at 40°C for 20 minutes; add 1700g of anhydrous N,N-dimethylformamide, and continue stirring for 10 minutes; add 350g of the isocyanate-terminated carboxyl betaine polymer obtained in Step 3, and stir at 40°C for 30 minutes; after cooling the system to 25°C, add 12g of polyethylene glycol dimethyl ether 250 (dried at 4A molecular sieve for 24 hours), and stir for 5 minutes. Add 30g of polyethylene glycol dimethyl ether 500 dried through a 4A molecular sieve for 24 hours, and stir for 8 minutes; add 3200g of ultra-dry acetone and stir for 10 minutes; filter through a 100μm PTFE filter; finally add 6g of dibutyltin dilaurate and stir for 3 minutes to obtain 5916g of low-water-content time-controlled grafting finishing solution; the water content of the finishing solution was determined to be 236mg / kg using the Karl Fischer method, and the finishing solution should be used within 30 minutes after the addition of dibutyltin dilaurate.

[0052] Step 5: Immerse 1000g of Egyptian long-staple cotton knitted fabric obtained in Step 1 into 5900g of low-moisture-content time-controlled grafting finishing solution obtained in Step 4. After immersion for 4 minutes, perform two dips and two nips. Calculate the nip-out rate based on the difference between the weight of the fabric after nipping and the weight of the dry fabric, so that the nip-out rate is 70%. Pre-dry the fabric after nipping in hot air at 50°C until the fabric weight is 1300g, and then bake it in hot air at 95°C for 25 minutes.

[0053] Step Six: Add the fabric dried in Step Five to a washing solution consisting of 20,000g deionized water, 100g ethanol, and 40g sodium bicarbonate, and wash at 40°C for 15 minutes; after draining, add 20,000g deionized water and wash for 10 minutes, then add another 20,000g deionized water and wash for 10 minutes, and finally add another 20,000g deionized water and wash for 10 minutes; dry the washed fabric in hot air at 70°C for 30 minutes, and then equilibrate in an environment with a temperature of 20°C and a relative humidity of 65% for 24 hours to obtain long-staple cotton knitted fabric.

[0054] Comparative Example 1:

[0055] The difference from Example 1 is that in step four, instead of adding 300g of the isocyanate-terminated carboxybetaine polymer obtained in step three, 300g of the hydroxyl-terminated carboxybetaine polymer obtained in step two is added, so that there are no isocyanate reaction end groups in the finished system; all other conditions are the same as in Example 1.

[0056] Comparative Example 2:

[0057] The difference from Example 1 is that in step four, after adding 3000g of ultra-dry acetone and stirring for 10 minutes, an additional 93g of deionized water is added to increase the water content of the low water content time-controlled grafting solution; all other conditions are the same as in Example 1.

[0058] Comparative Example 3:

[0059] The difference from Example 1 is that 15g of anhydrous lithium chloride is not added in step four, and 15g of anhydrous N,N-dimethylformamide is used to make up the total mass of the finishing solution; all other conditions are the same as in Example 1.

[0060] Comparative Example 4:

[0061] The difference from Example 1 is that in step four, 10g of polyethylene glycol dimethyl ether 250, 25g of polyethylene glycol dimethyl ether 500, and 5g of dibutyltin dilaurate are added simultaneously with 300g of the isocyanate-terminated carboxybetaine polymer obtained in step three, instead of in the order of isocyanate-terminated carboxybetaine polymer, polyethylene glycol dimethyl ether 250, polyethylene glycol dimethyl ether 500, and dibutyltin dilaurate; all other conditions are the same as in Example 1.

[0062] Comparative Example 5:

[0063] The difference from Example 1 is that in step four, instead of adding 25g of polyethylene glycol dimethyl ether 500, the amount of polyethylene glycol dimethyl ether 250 is adjusted from 10g to 35g, so that the total amount of polyethylene glycol dimethyl ether is kept at 35g; all other conditions are the same as in Example 1.

[0064] Comparative Example 6:

[0065] The difference from Example 1 is that in step five, the fabric after being rolled with liquid is pre-dried in hot air at 50°C until the fabric weight is 1450g and then baked in hot air at 90°C for 30 minutes, instead of pre-drying until the fabric weight is 1280g; all other conditions are the same as in Example 1.

[0066] Sample preparation and conditioning before performance testing: The long-staple cotton knitted fabrics obtained in Examples 1-3, the long-staple cotton knitted fabrics obtained in Comparative Examples 1-6, and unfinished Egyptian long-staple cotton knitted greige fabric were used as test samples. All test samples were sampled after removing 50mm of the selvage, avoiding obvious creases, oil stains, and weaving defects. All samples were conditioned according to the standard atmospheric conditions for textile conditioning and testing as specified in GB / T6529-2008, with conditioning conditions of 20°C, 65% relative humidity, and a conditioning time of 24 hours.

[0067] Water droplet diffusion time: The test method for moisture absorption and quick-drying combination of textiles in GB / T21655.1-2023 was used. Five 100mm×100mm samples were cut from each sample and placed flat on a horizontal test platform with the skin-contact side facing up. 0.2mL of deionized water was added to the center of the sample using a micropipette. The time required for the water droplet to completely diffuse and no longer show obvious specular reflection was recorded. The arithmetic mean of the test results of the five samples was taken as the water droplet diffusion time.

[0068] Vapor absorption height: The test method for moisture absorption and quick-drying combination of textiles in GB / T21655.1-2023 was adopted. Five 30mm×250mm samples were cut along the longitudinal direction of the fabric. The lower end of the sample was vertically immersed in deionized water for 10mm. The test environment temperature was 20°C and the relative humidity was 65%. The height of the water rising along the sample after 30 minutes was recorded. The arithmetic mean of the test results of the five samples was taken as the wicking height.

[0069] Evaporation and drying time: Refer to the test method for moisture absorption and quick-drying combination of textiles in GB / T21655.1-2023. Cut five 100mm×100mm samples for each sample, weigh them after equilibration in an environment of 20°C and 65% relative humidity, and then uniformly add 0.2mL of deionized water to the center of the sample. Record the time required for the sample mass to recover to the point where the increase in mass before adding water is no more than 0.005g. Take the arithmetic mean of the test results of the five samples as the evaporation and drying time.

[0070] Moisture permeability: The moisture permeability test of fabrics was conducted according to the moisture absorption method in GB / T12704.1-2009. Three circular specimens with a diameter larger than the opening of the moisture permeability cup were cut for each sample. The desiccant was placed in the moisture permeability cup, with the skin-contact side of the specimen facing the high humidity side. The test chamber temperature was 38°C and the relative humidity was 90%. After equilibration for 1 hour, the initial mass was weighed, and then weighed at specified intervals. The water vapor permeation per unit area over 24 hours was calculated, and the arithmetic mean of the three parallel samples was taken as the moisture permeability.

[0071] Air permeability: Tested according to the method for air permeability of fabrics in GB / T5453-1997. Three samples of at least 200mm × 200mm each were cut for each test. The test pressure difference was 100Pa, and the test area was 20cm². 2 Five different locations were selected for testing on each sample, avoiding fabric edges, creases and obvious defects. The arithmetic mean of the 15 test points was taken as the air permeability.

[0072] Wet-state skin adhesion: The test samples were cut into 50mm×100mm specimens, and 5 specimens of each sample were tested. The specimens were placed with the skin-facing side down on the surface of a silicone sheet for simulated skin that had been moistened with deionized water. The surface of the silicone sheet for simulated skin was pre-coated with 0.20g of deionized water. The specimens were pressed together with a 200g weight for 60s in an environment with a temperature of 20°C and a relative humidity of 65%. Then, an electronic fabric peel test device was used to peel the fabric along the 180° direction at a speed of 100mm / min. The average force value during the stable peeling stage was recorded, and the arithmetic mean of the 5 specimens was taken as the wet-state skin adhesion.

[0073] Tensile strength: The tensile strength was determined according to the fabric strip method in GB / T3923.1-2013. Five 50mm×200mm samples were cut along the longitudinal direction of the fabric, with a clamping distance of 100mm and a tensile speed of 100mm / min. The maximum breaking force was recorded, and the arithmetic mean of the test results of the five samples was taken as the tensile strength.

[0074] Table 1 Performance Test Results

[0075] sample Water diffusion time / s 30min wicking height / mm Evaporation drying time / min <![CDATA[Water vapor transmission rate / g / (m 2 ·24 h)]]> air permeability / mm / s Adhesion to skin in wet conditions / cN Longitudinal fracture strength / N Unfinished fabric 8.6 65.4 51.8 6575 486.2 48.6 335.8 Example 1 2.6 168.4 21.8 10126 443.6 18.4 337.4 Example 2 3.5 149.2 27.4 9138 462.7 23.7 339.1 Example 3 2.9 172.7 24.2 9824 418.9 21.5 331.6 Comparative Example 1 5.9 108.6 39.5 7356 452.4 33.8 336.5 Comparative Example 2 6.7 92.4 44.6 7048 462.6 40.3 326.8 Comparative Example 3 5.6 104.8 38.1 7884 455.1 35.1 334.2 Comparative Example 4 5.2 119.3 35.7 8162 416.8 31.4 331.8 Comparative Example 5 4.8 127.5 33.2 8458 434.7 28.6 333.5 Comparative Example 6 4.4 133.1 37.3 7521 356.9 37.2 324.7

[0076] As can be seen from Table 1, although the unfinished fabric maintains a high air permeability, the water droplet diffusion time is 8.6s, the wicking height is only 65.4mm after 30min, and the wet skin adhesion reaches 48.6cN. This indicates that it is difficult to achieve both rapid moisture absorption and wicking and low wet adhesion by simply relying on the Egyptian long-staple cotton knitting structure.

[0077] In Comparative Example 1, after replacing the isocyanate-terminated carboxybetaine polymer with a hydroxyl-terminated carboxybetaine polymer, the water diffusion time was shortened to 5.9 s and the wicking height was increased to 108.6 mm. However, the evaporation drying time remained at 39.5 min and the wet skin adhesion force was 33.8 cN. This indicates that although introducing hydrophilic zwitterionic segments can improve the initial water absorption, it is difficult to fully form a stable and continuous surface moisture-wicking structure. In Comparative Example 2, after increasing the water content of the finishing solution, the water diffusion time was 6.7 s and the wicking height was 92.4 mm. The breaking strength was reduced to 326.8 N, indicating that excessive water may consume some of the isocyanate reaction end groups and cause uneven deposition of the finishing layer.

[0078] Comparative Examples 3 to 5, which lacked anhydrous lithium chloride, had their addition sequence changed, or had polyethylene glycol dimethyl ether 500 removed, respectively, all showed lower moisture wicking, moisture permeability, and low adhesion performance than Example 1. This indicates that the fiber swelling / dispersion aiding effect of anhydrous lithium chloride, the regulation effect of the two-stage polyether, and the timing control of the catalyst addition jointly affect the distribution of the finishing solution on the cotton fiber surface. In Comparative Example 6, the pre-drying endpoint mass was increased to 1450g. Although the water diffusion time could reach 4.4s, the air permeability decreased to 356.9mm / s, the wet skin adhesion increased to 37.2cN, and the breaking strength decreased to 324.7N. This indicates that excessively wet baking can easily lead to restricted channels between coils or excessive accumulation of the finishing layer.

[0079] Examples 1 to 3 all exhibited shorter drip diffusion time, higher wicking height, shorter evaporation drying time, and lower wet skin adhesion. Among them, Example 1 had the best overall performance with a drip diffusion time of 2.6s, a wicking height of 168.4mm at 30min, an evaporation drying time of 21.8min, a moisture permeability of 10126.0g / (m²·24h), and a wet skin adhesion of 18.4cN. Example 2 maintained good air permeability and tensile strength due to its lower grafting load, but its moisture wicking speed was slightly lower. Example 3 had the highest wicking height due to its higher polymer content and roll-off rate, but its air permeability and tensile strength decreased slightly.

[0080] The above results indicate that there is a synergistic effect between isocyanate-terminated carboxyl betaine polymer, low-water aprotic system, anhydrous lithium chloride / diethylene glycol dimethyl ether timing regulation and pre-drying endpoint control. Without significantly sacrificing the basic performance of knitted fabrics, a relatively stable hydrophilic moisture-wicking layer can be formed on the outer surface of long-staple cotton fibers, thereby achieving simultaneous improvement in moisture absorption and wicking, quick drying and low wet adhesion properties.

[0081] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A long-staple cotton knitted fabric, comprising a long-staple cotton knitted base fabric and a hydrophilic moisture-wicking layer fixed to the outer surface of cotton fibers of the long-staple cotton knitted base fabric, characterized in that, By weight, the long-staple cotton knitted fabric is obtained by impregnating 1,000 parts of pretreated and dried long-staple cotton knitted greige fabric and 4,800-5,900 parts of low-moisture time-controlled grafting finishing solution with two dips and two nips, pre-drying, baking, washing and drying. The low-moisture-content time-controlled grafting solution is prepared by mixing the following raw materials in the order listed: 450-600 parts anhydrous dimethyl sulfoxide, 12-18 parts anhydrous lithium chloride, 1300-1700 parts anhydrous N,N-dimethylformamide, 250-350 parts isocyanate-terminated carboxylic betaine polymer, 8-12 parts polyethylene glycol dimethyl ether 250, 20-30 parts polyethylene glycol dimethyl ether 500, 2800-3200 parts ultra-dry acetone, and 4-6 parts dibutyltin dilaurate; The isocyanate-terminated carboxylic betaine polymer has a number average molecular weight of 4000-8000 and an isocyanate group mass fraction of 4‰-8‰. The water content of the low-moisture-content time-controlled grafting solution is 100-300 mg / kg; The padding is a two-dip, two-roll process with a roll-off rate of 60%-70%; the pre-drying is done in 50°C hot air until the fabric weight is 125%-130% of the dry fabric weight; the baking is done in 85°C-95°C hot air for 25-35 minutes.

2. The long-staple cotton knitted fabric according to claim 1, characterized in that, In the hydrophilic moisture-wicking layer, the isocyanate-terminated carboxy betaine polymer is fixed to the outer surface layer of the cotton fiber through the reaction of its isocyanate groups with the hydroxyl groups on the surface of the long-staple cotton fiber to form urethane bonds.

3. The long-staple cotton knitted fabric according to claim 1, characterized in that, The long-staple cotton knitted fabric is a double-sided weft-knitted fabric obtained by weaving 100% Egyptian long-staple cotton combed compact yarn on a double-sided circular weft machine; the yarn specification is 60S / 2, and the weight is 160g / m². 2 The fabric has a width of 180cm, an average fiber length of not less than 34mm, a longitudinal density of 120 loops / 10cm, and a transverse density of 90 loops / 10cm.

4. The long-staple cotton knitted fabric according to claim 1, characterized in that, The isocyanate-terminated carboxybetaine polymer is obtained by reacting a hydroxyl-terminated carboxybetaine polymer with isophorone diisocyanate; the hydroxyl-terminated carboxybetaine polymer is obtained by polymerizing 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate in the presence of 2-mercaptoethanol and 2,2′-azobisisobutyronitrile.

5. The long-staple cotton knitted fabric according to claim 4, characterized in that, The mass ratio of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, 2-mercaptoethanol, and 2,2′-azobisisobutyronitrile in the raw materials for preparing the hydroxyl-terminated carboxybetaine polymer is 500:3-10:

5.

6. The long-staple cotton knitted fabric according to claim 4, characterized in that, The mass ratio of hydroxyl-terminated carboxybetaine polymer to isophorone diisocyanate in the raw materials for preparing the isocyanate-terminated carboxybetaine polymer is 350:45-80.

7. The long-staple cotton knitted fabric according to claim 4, characterized in that, The hydroxyl-terminated carboxybetaine polymer has a number-average molecular weight of 3500-7800, a molecular weight distribution index of 1.6-2.2, and a terminal hydroxyl content of 125-240 μmol / g.

8. The long-staple cotton knitted fabric according to claim 1, characterized in that, The low-moisture-content time-controlled grafting finishing solution is used to treat the long-staple cotton knitted fabric within 30 minutes after the addition of the dibutyltin dilaurate.

9. The long-staple cotton knitted fabric according to claim 1, characterized in that, The moisture content of the ultra-dry acetone is less than 50 mg / kg.

10. A method for preparing a long-staple cotton knitted fabric according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Pre-treat, wash and dry the long-staple cotton knitted fabric to obtain the pre-treated fabric; (2) Preparation of hydroxyl-terminated carboxylic betaine polymer; (3) React the hydroxyl-terminated carboxy betaine polymer with isophorone diisocyanate to obtain isocyanate-terminated carboxy betaine polymer; (4) Anhydrous dimethyl sulfoxide, anhydrous lithium chloride, anhydrous N,N-dimethylformamide, the isocyanate-terminated carboxy betaine polymer, polyethylene glycol dimethyl ether 250, polyethylene glycol dimethyl ether 500, ultra-dry acetone and dibutyltin dilaurate are mixed in sequence to obtain a low-water-content time-controlled grafting solution. (5) The pretreated fabric is impregnated, dipped twice and rubbed twice, pre-dried and baked using the low moisture content time-controlled grafting finishing solution; (6) Wash, dry and balance the baked fabric to obtain the long-staple cotton knitted fabric.