High-elasticity fiber fabric and forming process thereof

Abstract

This invention relates to the field of textile fabric technology, specifically to a high-elasticity fiber fabric and its molding process. The fabric comprises a knitted base fabric woven from nylon-coated modified polyurethane elastic fiber-coated yarn. The modified polyurethane elastic fiber comprises a core elastic polyurethane phase and a surface hard-segment enriched phase. The surface phase is formed by a composite of polycarbonate diol-type high-hardness polyurethane prepolymer, hydrophilic fumed silica, hydrophobic fumed silica, and hydroxyalkyl-terminated polydimethylsiloxane. This invention significantly improves the interfacial stability between the core yarn and nylon without increasing fiber usage or fabric tightness, giving the fabric high elastic recovery rate, low dimensional change after washing, and excellent sweat and heat resistance, thus solving the problem of easy loosening and deformation in traditional high-elasticity fabrics.

Description

Technical Field

[0001] This invention relates to the field of textile fabric technology, and in particular to a high-elasticity fiber fabric and its forming process. Background Technology

[0002] In applications requiring highly elastic knitted fabrics such as sportswear and medical bandages, polyurethane elastic fibers are often used as core fibers in combination with outer fibers such as nylon to enhance overall elasticity. However, in existing technologies, the interfacial bonding between ordinary polyurethane elastic fibers and nylon mainly relies on physical coating. During repeated stretching, the core fiber and outer fiber are prone to relative slippage due to modulus differences, leading to the core fiber gradually being exposed or even breaking.

[0003] Especially during home washing, alkaline detergents and mechanical rubbing further weaken the interfacial bonding, significantly increasing the fabric's shrinkage rate after washing and affecting its fit. In hot, humid environments, polyurethane segments are prone to hydrolysis and plasticization, drastically reducing elastic recovery and causing the fabric to loosen and deform.

[0004] Although existing technologies have attempted to improve the above problems by adjusting the wrapping twist or increasing the fabric tightness, excessive wrapping twist reduces the softness of the fabric, while excessive fabric tightness sacrifices breathability. Neither can fundamentally improve the chemical and physical interface stability between the core yarn and the outer fiber, making it difficult to simultaneously meet the multiple requirements of high elastic recovery, low shrinkage after washing, and resistance to sweat and damp heat. This has become a key bottleneck restricting the performance improvement of high elastic knitted fabrics. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a high-elasticity fiber fabric and its molding process, so as to improve the interfacial anti-slip stability of nylon-coated polyurethane elastic fiber-coated yarn after repeated stretching, washing and sweat heat treatment without increasing the nylon coating ratio, coating twist, knitting density and heat setting strength, while taking into account the intrinsic elastic recovery rate of polyurethane elastic fiber.

[0006] To achieve the above objectives, the present invention provides a high-elasticity fiber fabric, comprising a knitted base fabric, wherein the knitted base fabric is woven from nylon-coated modified polyurethane elastic fiber coated yarn, wherein the nylon-coated modified polyurethane elastic fiber coated yarn comprises a modified polyurethane elastic fiber as a core yarn and nylon outer yarn covering the outside of the core yarn.

[0007] The modified polyurethane elastic fiber includes a core elastic polyurethane phase and a surface hard segment enriched phase located outside the core elastic polyurethane phase.

[0008] The modified polyurethane elastic fiber is formed from polyurethane solids comprising a matrix polyurethane and a polycarbonate diol-type high-hardness segment polyurethane prepolymer. The matrix polyurethane accounts for 90%-92% of the total mass of the polyurethane solids, with the remainder being the polycarbonate diol-type high-hardness segment polyurethane prepolymer.

[0009] The surface hard segment enriched phase includes a phase structure formed by the polycarbonate diol type high hard segment polyurethane prepolymer, hydrophilic fumed silica, hydrophobic fumed silica and hydroxyalkyl-terminated polydimethylsiloxane.

[0010] The polycarbonate diol-type high-hardness polyurethane prepolymer has a hard segment mass fraction of 32%-36% and an isocyanate group mass fraction of 8‰-12‰.

[0011] The mass fraction of the hard segment of the polycarbonate diol-type high-hardness polyurethane prepolymer is calculated by the following formula: Mass fraction of hard segment = (mass of 4,4'-diphenylmethane diisocyanate feed + mass of 1,4-butanediol feed) / (mass of polycarbonate diol feed + mass of 4,4'-diphenylmethane diisocyanate feed + mass of 1,4-butanediol feed) × 100%.

[0012] The mass fraction of isocyanate groups in the polycarbonate diol-type high-hardness polyurethane prepolymer was determined by di-n-butylamine-hydrochloric acid back titration and expressed in ‰ based on the mass of the prepolymer solids.

[0013] Furthermore, the matrix polyurethane is formed by reacting 1800 parts by weight of polytetrahydrofuran diol, 550 parts by weight of 4,4'-diphenylmethane diisocyanate, 67 parts by weight of ethylenediamine and 12 parts by weight of diethylamine, wherein the number average molecular weight of the polytetrahydrofuran diol is 1800.

[0014] Furthermore, the polycarbonate diol-type high-hardness polyurethane prepolymer is formed by reacting polycarbonate diol, 4,4'-diphenylmethane diisocyanate and 1,4-butanediol with a number average molecular weight of 1000-2000.

[0015] Furthermore, the surface hard segment enriched phase is formed from the following raw materials in parts by weight: 145-170 parts of polycarbonate diol with a number average molecular weight of 1000-2000, 61.1-78.5 parts of 4,4'-diphenylmethane diisocyanate, 7.1-17.2 parts of 1,4-butanediol, 2.5-3.6 parts of hydrophilic fumed silica, 1.6-2.8 parts of hydrophobic fumed silica, and 6-10 parts of hydroxyalkyl-terminated polydimethylsiloxane.

[0016] Furthermore, the surface hard segment enriched phase is formed by first introducing hydrophilic fumed silica into the polycarbonate diol-type high hard segment polyurethane prepolymer, then introducing hydrophobic fumed silica, and subsequently introducing hydroxyalkyl-terminated polydimethylsiloxane.

[0017] Furthermore, the specific surface area of ​​the hydrophilic fumed silica is 200 m². 2 / g; The hydrophobic fumed silica is hydrophobic fumed silica post-treated with hexamethyldisilazane.

[0018] Furthermore, the number average molecular weight of the hydroxyalkyl-terminated polydimethylsiloxane is 4000.

[0019] Furthermore, in the nylon-coated modified polyurethane elastic fiber coated yarn, the mass ratio of the modified polyurethane elastic fiber to the nylon outer fiber is 1:3.

[0020] Furthermore, the present invention also provides a molding process for a high-elasticity fiber fabric, comprising the following steps:

[0021] S1. Preparation of matrix polyurethane spinning solution: Polytetrahydrofuran diol and N,N-dimethylacetamide are mixed and dehydrated, and 4,4'-diphenylmethane diisocyanate is added to react and obtain an isocyanate-terminated matrix polyurethane prepolymer solution; ethylenediamine and diethylamine are dissolved in N,N-dimethylacetamide to form a chain extension and end-capping solution, and the chain extension and end-capping solution is added to the matrix polyurethane prepolymer solution to obtain the matrix polyurethane spinning solution;

[0022] S2. Preparation of polycarbonate diol type high hardness segment polyurethane prepolymer: Polycarbonate diol with a number average molecular weight of 1000-2000 is mixed with N,N-dimethylacetamide and dehydrated. 4,4'-diphenylmethane diisocyanate and bismuth isooctanoate polyurethane catalyst are added and reacted. Then 1,4-butanediol and N,N-dimethylacetamide are added and reacted to obtain polycarbonate diol type high hardness segment polyurethane prepolymer.

[0023] S3. Preparation of surface segment gradient modified prepolymer solution: Add hydrophilic fumed silica dispersion to the polycarbonate diol type high hardness polyurethane prepolymer obtained in step S2, then add hydrophobic fumed silica dispersion, then add hydroxyalkyl-terminated polydimethylsiloxane for reaction, then add n-butanol to continue the reaction, and obtain surface segment gradient modified prepolymer solution.

[0024] S4. Preparation of modified polyurethane spinning solution: Add the surface segment gradient modified prepolymer solution obtained in step S3 to the matrix polyurethane spinning solution obtained in step S1, and then add antioxidant and N,N-dimethylacetamide. Mix, filter and degas to obtain modified polyurethane spinning solution.

[0025] S5. Dry spinning: The modified polyurethane spinning solution obtained in step S4 is subjected to dry spinning. The amount of N,N-dimethylacetamide volatilized at the outlet of the first section of the dry spinning channel is controlled to be 35%-45%, the draw ratio of the second section of the channel is 1.8-2.2 times, and the cumulative draw ratio of the third section of the channel is 2.8-3.2 times, to obtain modified polyurethane elastic fibers.

[0026] S6. Coating, weaving and finishing: Using the modified polyurethane elastic fiber obtained in step S5 as the core yarn and nylon 6 fully drawn yarn as the outer yarn, a nylon-coated modified polyurethane elastic fiber coated yarn is made. The nylon-coated modified polyurethane elastic fiber coated yarn is woven into a knitted fabric, and the knitted fabric is washed, rinsed, dehydrated and heat-set to obtain the high-elasticity fiber fabric.

[0027] Further, in step S5, the modified polyurethane spinning solution is maintained at 45°C and fed into a dry spinning duct via a metering pump. The spinneret assembly has 8 holes with a diameter of 80µm. The total extrusion rate of the modified polyurethane spinning solution is 7.5-8.5g / min. Dry hot air is introduced into the duct with an average axial wind speed of 0.8m / s. The temperature of the first section of the duct is 108-115°C, the temperature of the second section is 158-162°C, and the temperature of the third section is 202-208°C. The winding speed is 620-680m / min, thereby obtaining modified polyurethane elastic fibers.

[0028] The beneficial effects of this invention are:

[0029] This invention introduces a specific proportion of polycarbonate diol-type high-hardness polyurethane prepolymer into the matrix polyurethane, and combines it with the sequential composite of hydrophilic fumed silica, hydrophobic fumed silica and hydroxyalkyl-terminated polydimethylsiloxane to construct a hard-segment enriched phase with controllable thickness on the fiber surface, thereby enhancing the surface polarity and interfacial bonding activity of the core filament from a chemical structure perspective.

[0030] This invention induces a gradient distribution of the surface hard segment phase in the fiber radial direction by matching the solvent evaporation amount in the first stage of dry spinning with the segmented draft ratio. This maintains the elastic recovery ability of the core layer while significantly improving the interfacial anti-slip performance through physical interlocking and hydrogen bonding between the hard segment enrichment layer and the nylon fiber. This heterogeneous structure design of "core layer elasticity - surface layer reinforcement" effectively solves the problem of poor coating stability caused by the surface inertness of traditional spandex core yarns. In addition, the reactive polydimethylsiloxane segments introduced into the surface layer endow the fiber with excellent hydrolysis and perspiration resistance, enabling the fabric to maintain a high elastic recovery rate even after multiple washings and damp heat treatments. Experiments have shown that this design increases the fabric's lateral elastic recovery rate to over 94.6%, reduces the absolute value of dimensional change rate to less than 1.8% after 10 washes, maintains an elasticity rate of over 94% after sweat and heat treatment, and reduces the exposed core length by more than 90% compared to conventional products. At the same time, it avoids the problem of fabric stiffness caused by excessively increasing the covering density, achieving a synergistic improvement in elasticity, durability, and comfort. Detailed Implementation

[0031] 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.

[0032] Raw material sources: The polytetrahydrofuran glycol used was BASF's PolyTHF 1800, with a number average molecular weight of 1800; the polycarbonate glycol with a number average molecular weight of 1000 was Asahi Kasei's Duranol T5651, the polycarbonate glycol with a number average molecular weight of 1500 was Asahi Kasei's Duranol AK021E, and the polycarbonate glycol with a number average molecular weight of 2000 was Asahi Kasei's Duranol T5652; the hydrophilic fumed silica was Evonik's AEROSIL 200, with a specific surface area of ​​200 m². 2 / g; the hydrophobic fumed silica used was AEROSIL R812S from Evonik, which is a hydrophobic fumed silica post-treated with hexamethyldisilazane; the hydroxyalkyl-terminated polydimethylsiloxane was sourced from Nanjing SiSiB Company, with a number average molecular weight of 4000; the bismuth isooctanoate polyurethane catalyst used was BCAT-E20C organic bismuth catalyst from Guangzhou Yourun Fine Chemical Co., Ltd.; the antioxidant 1010 used was Irganox 1010 from BASF; the fatty alcohol polyoxyethylene ether used was industrial grade fatty alcohol polyoxyethylene ether AEO-9; the nylon 6 fully drawn yarn used was nylon 6 fully drawn yarn from Hengshen Group, with a specification of 40D / 24F, semi-dull.

[0033] Example 1:

[0034] Step 1: Add 1800g of polytetrahydrofuran glycol and 1800g of N,N-dimethylacetamide to a dry reaction vessel, stir at 80r / min under nitrogen protection, and dehydrate at 80℃ for 60min. Cool the system to 70℃, then add 550g of 4,4'-diphenylmethane diisocyanate, and react at 70℃ for 120min to obtain an isocyanate-terminated matrix polyurethane prepolymer solution. Separately, dissolve 67g of ethylenediamine and 12g of diethylamine in 2500g of N,N-dimethylacetamide, cool the resulting solution to 20℃, and add it to the aforementioned matrix polyurethane prepolymer solution within 30min. Continue stirring for 90min to obtain the matrix polyurethane spinning solution.

[0035] Step 2: Add 150g of polycarbonate diol with a number average molecular weight of 2000 and 120g of N,N-dimethylacetamide to another dry reaction vessel. Under nitrogen protection, heat to 80℃ and dehydrate for 60min. Cool the system to 70℃, then add 61g of 4,4'-diphenylmethane diisocyanate and 200mg of bismuth isooctanoate polyurethane catalyst. React at 70℃ for 90min. Then add 13g of 1,4-butanediol and 40g of N,N-dimethylacetamide, and react at 70℃ for 60min to obtain a polycarbonate diol-type high-hardness polyurethane prepolymer. The hard segment mass fraction of this polycarbonate diol-type high-hardness polyurethane prepolymer is about 33%, the isocyanate group mass fraction is about 9.2‰, and it accounts for about 8.4% of the total solid mass of polyurethane by solid mass.

[0036] Step 3: First, dry 3g of hydrophilic fumed silica at 150℃ and 80kPa vacuum for 180min, then cool it to 25℃ in dry nitrogen. Add 60g of N,N-dimethylacetamide, shear at 3000r / min for 10min, and ultrasonically disperse at 200W for 20min to obtain a hydrophilic fumed silica dispersion. The particle size corresponding to 90% cumulative volume distribution of this hydrophilic fumed silica dispersion is measured to be 650nm. Add this hydrophilic fumed silica dispersion to the polycarbonate diol-type high-hardness polyurethane prepolymer obtained in Step 2 at 75℃, and stir at 120r / min for 60min. Then add 2g of hydrophobic fumed silica to 40g of... In N,N-dimethylacetamide, the mixture was sheared at 3000 r / min for 10 min and ultrasonically dispersed at 200 W for 20 min before being added to the above system. The cumulative volume distribution of the particles in the system after adding hydrophobic fumed silica was measured to be 90%, corresponding to a particle size of 850 nm. The mixture was stirred at 75 °C for 40 min, and then 8 g of hydroxyalkyl-terminated polydimethylsiloxane and 20 g of N,N-dimethylacetamide were added. The mixture was reacted at 75 °C for 50 min, and then 4 g of n-butanol was added and the reaction was continued for 30 min to obtain a surface segment gradient modified prepolymer solution.

[0037] Step 4: Add all the surface segment gradient modified prepolymer solution obtained in Step 3 to all the matrix polyurethane spinning solution obtained in Step 1, then add 10g of antioxidant 1010 and 200g of N,N-dimethylacetamide, stir at 100r / min for 120min at 45℃, then filter through a 5µm filter and a 1µm filter in sequence, and degas under a vacuum of 90kPa for 120min to obtain the modified polyurethane spinning solution;

[0038] Step 5: The modified polyurethane spinning solution obtained in Step 4 is maintained at 45℃ and fed into the dry spinning duct via a metering pump. The spinneret assembly has 8 holes with a diameter of 80µm. The total extrusion rate of the modified polyurethane spinning solution is 8g / min. Dry hot air is introduced into the duct with an average axial wind speed of 0.8m / s. The temperature of the first section of the duct is 110℃. The volatilization rate of N,N-dimethylacetamide at the outlet of the first section is controlled to be 40% by controlling the hot air flow rate and the duct temperature. The volatilization rate of N,N-dimethylacetamide is calculated per unit time at the inlet of the first section. The difference between the mass of N,N-dimethylacetamide entering the filament and the mass of N,N-dimethylacetamide remaining in the first-section outlet filament was calculated as a percentage of the mass of N,N-dimethylacetamide entering the first-section inlet per unit time. The mass of N,N-dimethylacetamide remaining in the first-section outlet filament was determined by headspace gas chromatography. The temperature of the second section of the tunnel was 160℃, and the draw ratio was 2. The temperature of the third section of the tunnel was 205℃, the cumulative draw ratio was 3, and the winding speed was 650m / min, resulting in 40D modified polyurethane elastic fiber.

[0039] Step 6: 1000g of modified polyurethane elastic fiber is pre-stretched 3 times at 25℃ to serve as the core yarn, and 3000g of nylon 6 fully drawn yarn is used as the outer yarn. The nylon-coated modified polyurethane elastic fiber covered yarn is made with a covering twist of 800T / m, and then wound after being relaxed for 30s under 80℃ steam conditions.

[0040] Step 7: 4000g of nylon-coated modified polyurethane elastic fiber coated yarn is woven into a knitted fabric on a 32-needle / 25.4mm circular knitting machine. The loop length is 2600µm, the yarn tension is 4cN, and the fabric weight is 220g / m2. 2000g of knitted fabric is added to 40000g of water, 40g of fatty alcohol polyoxyethylene ether, and 20g of sodium carbonate. It is washed at 40℃ for 20min, then rinsed with clean water until the pH of the residual liquid on the fabric surface is 7. It is then centrifuged to remove water until the liquid content is 60%. Subsequently, it is heat-set at 165℃ for 45s with an overfeed rate of 5% and a width of 150cm to obtain a high-elasticity fiber fabric.

[0041] Example 2:

[0042] Step 1: Add 1800g of polytetrahydrofuran glycol and 1800g of N,N-dimethylacetamide to a dry reaction vessel, stir at 80r / min under nitrogen protection, and dehydrate at 80℃ for 60min. Cool the system to 70℃, then add 550g of 4,4'-diphenylmethane diisocyanate, and react at 70℃ for 120min to obtain an isocyanate-terminated matrix polyurethane prepolymer solution. Separately, dissolve 67g of ethylenediamine and 12g of diethylamine in 2500g of N,N-dimethylacetamide, cool the resulting solution to 20℃, and add it to the aforementioned matrix polyurethane prepolymer solution within 30min. Continue stirring for 90min to obtain the matrix polyurethane spinning solution.

[0043] Step 2: Add 145g of polycarbonate diol with a number average molecular weight of 1000 and 120g of N,N-dimethylacetamide to another dry reaction vessel. Heat to 80℃ under nitrogen protection and dehydrate for 60min. Cool the system to 70℃, then add 61.1g of 4,4'-diphenylmethane diisocyanate and 180mg of bismuth isooctanoate polyurethane catalyst. React at 70℃ for 90min. Then add 7.1g of 1,4-butanediol and 40g of N,N-dimethylacetamide, and react at 70℃ for 60min to obtain a polycarbonate diol-type high-hardness polyurethane prepolymer. The hard segment mass fraction of this polycarbonate diol-type high-hardness polyurethane prepolymer is approximately 32%, the isocyanate group mass fraction is approximately 8.0‰, and it accounts for approximately 8.1% of the total solid mass of the polyurethane by solids mass.

[0044] Step 3: First, dry 2.5g of hydrophilic fumed silica at 150℃ and 80kPa vacuum for 180min, then cool it to 25℃ in dry nitrogen. Next, add 55g of N,N-dimethylacetamide, shear at 3000r / min for 10min, and ultrasonically disperse at 200W for 20min to obtain a hydrophilic fumed silica dispersion. The particle size corresponding to the 90% cumulative volume distribution of this hydrophilic fumed silica dispersion is measured to be 720nm. Add this hydrophilic fumed silica dispersion to the polycarbonate diol-type high-hardness polyurethane prepolymer obtained in Step 2 at 75℃, and stir at 120r / min for 60min. Then, add 1.6g of hydrophobic fumed silica to 36g of... In N,N-dimethylacetamide, the mixture was sheared at 3000 r / min for 10 min and ultrasonically dispersed at 200 W for 20 min before being added to the above system. The cumulative volume distribution of the particles after adding hydrophobic fumed silica was measured to be 90%, corresponding to a particle size of 950 nm. The mixture was stirred at 75 °C for 40 min, and then 6 g of hydroxyalkyl-terminated polydimethylsiloxane and 20 g of N,N-dimethylacetamide were added. The mixture was reacted at 75 °C for 50 min, and then 4 g of n-butanol was added and the reaction was continued for 30 min to obtain a surface segment gradient modified prepolymer solution.

[0045] Step 4: Add all the surface segment gradient modified prepolymer solution obtained in Step 3 to all the matrix polyurethane spinning solution obtained in Step 1, then add 10g of antioxidant 1010 and 200g of N,N-dimethylacetamide, stir at 100r / min for 120min at 45℃, then filter through a 5µm filter and a 1µm filter in sequence, and degas under a vacuum of 90kPa for 120min to obtain the modified polyurethane spinning solution;

[0046] Step 5: The modified polyurethane spinning solution obtained in Step 4 is maintained at 45℃ and fed into the dry spinning duct via a metering pump. The spinneret assembly has 8 holes with a diameter of 80µm. The total extrusion rate of the modified polyurethane spinning solution is 7.5g / min. Dry hot air is introduced into the duct with an average axial wind speed of 0.8m / s. The temperature of the first section of the duct is 108℃. The volatilization rate of N,N-dimethylacetamide at the outlet of the first section is controlled to be 35% by controlling the hot air flow rate and the duct temperature. The volatilization rate of N,N-dimethylacetamide is calculated based on the unit time at the inlet of the first section. The difference between the mass of N,N-dimethylacetamide entering the filament and the mass of N,N-dimethylacetamide remaining in the first-section outlet filament was calculated as a percentage of the mass of N,N-dimethylacetamide entering the filament per unit time in the first section. The mass of N,N-dimethylacetamide remaining in the first-section outlet filament was determined by headspace gas chromatography. The temperature of the second section of the tunnel was 158℃, and the draw ratio was 1.8. The temperature of the third section of the tunnel was 202℃, the cumulative draw ratio was 2.8, and the winding speed was 620m / min, resulting in 40D modified polyurethane elastic fiber.

[0047] Step 6: 1000g of modified polyurethane elastic fiber is pre-stretched 3 times at 25℃ to serve as the core yarn, and 3000g of nylon 6 fully drawn yarn is used as the outer yarn. The nylon-coated modified polyurethane elastic fiber covered yarn is made with a covering twist of 800T / m, and then wound after being relaxed for 30s under 80℃ steam conditions.

[0048] Step 7: 4000g of nylon-coated modified polyurethane elastic fiber coated yarn is woven into a knitted fabric on a 32-needle / 25.4mm circular knitting machine. The loop length is 2600µm, the yarn tension is 4cN, and the fabric weight is 220g / m2. 2000g of knitted fabric is added to 40000g of water, 40g of fatty alcohol polyoxyethylene ether, and 20g of sodium carbonate. It is washed at 40℃ for 20min, then rinsed with clean water until the pH of the residual liquid on the fabric surface is 7. It is then centrifuged to remove water until the liquid content is 60%. Subsequently, it is heat-set at 165℃ for 45s with an overfeed rate of 5% and a width of 150cm to obtain a high-elasticity fiber fabric.

[0049] Example 3:

[0050] Step 1: Add 1800g of polytetrahydrofuran glycol and 1800g of N,N-dimethylacetamide to a dry reaction vessel, stir at 80r / min under nitrogen protection, and dehydrate at 80℃ for 60min. Cool the system to 70℃, then add 550g of 4,4'-diphenylmethane diisocyanate, and react at 70℃ for 120min to obtain an isocyanate-terminated matrix polyurethane prepolymer solution. Separately, dissolve 67g of ethylenediamine and 12g of diethylamine in 2500g of N,N-dimethylacetamide, cool the resulting solution to 20℃, and add it to the aforementioned matrix polyurethane prepolymer solution within 30min. Continue stirring for 90min to obtain the matrix polyurethane spinning solution.

[0051] Step 2: Add 160g of polycarbonate diol with a number average molecular weight of 1500 and 130g of N,N-dimethylacetamide to another dry reaction vessel. Heat to 80℃ under nitrogen protection and dehydrate for 60min. Cool the system to 70℃, then add 69.6g of 4,4'-diphenylmethane diisocyanate and 220mg of bismuth isooctanoate polyurethane catalyst. React at 70℃ for 90min. Then add 12.8g of 1,4-butanediol and 45g of N,N-dimethylacetamide, and react at 70℃ for 60min to obtain a polycarbonate diol-type high-hardness polyurethane prepolymer. The hard segment mass fraction of this polycarbonate diol-type high-hardness polyurethane prepolymer is approximately 34%, the isocyanate group mass fraction is approximately 10.2‰, and it accounts for approximately 9.1% of the total solid mass of the polyurethane by solids.

[0052] Step 3: First, dry 3.2g of hydrophilic fumed silica at 150℃ and 80kPa vacuum for 180min, then cool it to 25℃ in dry nitrogen. Next, add 65g of N,N-dimethylacetamide, shear at 3000r / min for 10min, and ultrasonically disperse at 200W for 20min to obtain a hydrophilic fumed silica dispersion. The particle size corresponding to the 90% cumulative volume distribution of this hydrophilic fumed silica dispersion is measured to be 630nm. Add this hydrophilic fumed silica dispersion to the polycarbonate diol-type high-hardness polyurethane prepolymer obtained in Step 2 at 75℃, and stir at 120r / min for 60min. Then, add 2.4g of hydrophobic fumed silica to 45g of... In N,N-dimethylacetamide, the mixture was sheared at 3000 r / min for 10 min and ultrasonically dispersed at 200 W for 20 min before being added to the above system. The cumulative volume distribution of the particles after adding hydrophobic fumed silica was measured to be 90%, corresponding to a particle size of 900 nm. The mixture was stirred at 75 °C for 40 min, and then 8.5 g of hydroxyalkyl-terminated polydimethylsiloxane and 22 g of N,N-dimethylacetamide were added. The mixture was reacted at 75 °C for 50 min, and then 4 g of n-butanol was added and the reaction was continued for 30 min to obtain a surface segment gradient modified prepolymer solution.

[0053] Step 4: Add all the surface segment gradient modified prepolymer solution obtained in Step 3 to all the matrix polyurethane spinning solution obtained in Step 1, then add 10g of antioxidant 1010 and 200g of N,N-dimethylacetamide, stir at 100r / min for 120min at 45℃, then filter through a 5µm filter and a 1µm filter in sequence, and degas under a vacuum of 90kPa for 120min to obtain the modified polyurethane spinning solution;

[0054] Step 5: The modified polyurethane spinning solution obtained in Step 4 is maintained at 45℃ and fed into the dry spinning duct via a metering pump. The spinneret assembly has 8 holes with a diameter of 80µm. The total extrusion rate of the modified polyurethane spinning solution is 8g / min. Dry hot air is introduced into the duct with an average axial wind speed of 0.8m / s. The temperature of the first section of the duct is 112℃. The volatilization rate of N,N-dimethylacetamide at the outlet of the first section is controlled to be 42% by controlling the hot air flow rate and the duct temperature. The volatilization rate of N,N-dimethylacetamide is calculated per unit time at the inlet of the first section. The difference between the mass of N,N-dimethylacetamide entering the filament and the mass of N,N-dimethylacetamide remaining in the first-section outlet filament was calculated as a percentage of the mass of N,N-dimethylacetamide entering the first-section inlet per unit time. The mass of N,N-dimethylacetamide remaining in the first-section outlet filament was determined by headspace gas chromatography. The temperature of the second section of the tunnel was 160℃, and the draw ratio was 2. The temperature of the third section of the tunnel was 205℃, the cumulative draw ratio was 3, and the winding speed was 650m / min, resulting in 40D modified polyurethane elastic fiber.

[0055] Step 6: 1000g of modified polyurethane elastic fiber is pre-stretched 3 times at 25℃ to serve as the core yarn, and 3000g of nylon 6 fully drawn yarn is used as the outer yarn. The nylon-coated modified polyurethane elastic fiber covered yarn is made with a covering twist of 800T / m, and then wound after being relaxed for 30s under 80℃ steam conditions.

[0056] Step 7: 4000g of nylon-coated modified polyurethane elastic fiber coated yarn is woven into a knitted fabric on a 32-needle / 25.4mm circular knitting machine. The loop length is 2600µm, the yarn tension is 4cN, and the fabric weight is 220g / m2. 2000g of knitted fabric is added to 40000g of water, 40g of fatty alcohol polyoxyethylene ether, and 20g of sodium carbonate. It is washed at 40℃ for 20min, then rinsed with clean water until the pH of the residual liquid on the fabric surface is 7. It is then centrifuged to remove water until the liquid content is 60%. Subsequently, it is heat-set at 165℃ for 45s with an overfeed rate of 5% and a width of 150cm to obtain a high-elasticity fiber fabric.

[0057] Example 4:

[0058] Step 1: Add 1800g of polytetrahydrofuran glycol and 1800g of N,N-dimethylacetamide to a dry reaction vessel, stir at 80r / min under nitrogen protection, and dehydrate at 80℃ for 60min. Cool the system to 70℃, then add 550g of 4,4'-diphenylmethane diisocyanate, and react at 70℃ for 120min to obtain an isocyanate-terminated matrix polyurethane prepolymer solution. Separately, dissolve 67g of ethylenediamine and 12g of diethylamine in 2500g of N,N-dimethylacetamide, cool the resulting solution to 20℃, and add it to the aforementioned matrix polyurethane prepolymer solution within 30min. Continue stirring for 90min to obtain the matrix polyurethane spinning solution.

[0059] Step 2: 170g of polycarbonate diol with a number average molecular weight of 2000 and 140g of N,N-dimethylacetamide were added to another dry reaction vessel. Under nitrogen protection, the mixture was heated to 80℃ and dehydrated for 60min. The system was then cooled to 70℃, followed by the addition of 78.5g of 4,4'-diphenylmethane diisocyanate and 240mg of bismuth isooctanoate polyurethane catalyst. The reaction was carried out at 70℃ for 90min. Then, 17.2g of 1,4-butanediol and 50g of N,N-dimethylacetamide were added, and the reaction was carried out at 70℃ for 60min to obtain a polycarbonate diol-type high-hardness polyurethane prepolymer. The hard segment mass fraction of this polycarbonate diol-type high-hardness polyurethane prepolymer was approximately 36%, the isocyanate group mass fraction was approximately 12.0‰, and it accounted for approximately 9.9% of the total solid mass of the polyurethane by solid mass.

[0060] Step 3: First, dry 3.6g of hydrophilic fumed silica at 150℃ and 80kPa vacuum for 180min, then cool it to 25℃ in dry nitrogen. Next, add 70g of N,N-dimethylacetamide, shear at 3000r / min for 10min, and ultrasonically disperse at 200W for 20min to obtain a hydrophilic fumed silica dispersion. The cumulative volume distribution of the hydrophilic fumed silica dispersion corresponds to a particle size of 600nm at 90%. Add this hydrophilic fumed silica dispersion to the polycarbonate diol-type high-hardness polyurethane prepolymer obtained in Step 2 at 75℃, and stir at 120r / min for 60min. Then, add 2.8g of hydrophobic fumed silica to 50g of... In N,N-dimethylacetamide, the mixture was sheared at 3000 r / min for 10 min and ultrasonically dispersed at 200 W for 20 min before being added to the above system. The cumulative volume distribution of the particles after adding hydrophobic fumed silica was measured to be 90%, corresponding to a particle size of 850 nm. The mixture was stirred at 75 °C for 40 min, and then 10 g of hydroxyalkyl-terminated polydimethylsiloxane and 25 g of N,N-dimethylacetamide were added. The mixture was reacted at 75 °C for 50 min, and then 4 g of n-butanol was added and the reaction was continued for 30 min to obtain a surface segment gradient modified prepolymer solution.

[0061] Step 4: Add all the surface segment gradient modified prepolymer solution obtained in Step 3 to all the matrix polyurethane spinning solution obtained in Step 1, then add 10g of antioxidant 1010 and 200g of N,N-dimethylacetamide, stir at 100r / min for 120min at 45℃, then filter through a 5µm filter and a 1µm filter in sequence, and degas under a vacuum of 90kPa for 120min to obtain the modified polyurethane spinning solution;

[0062] Step 5: The modified polyurethane spinning solution obtained in Step 4 is maintained at 45℃ and fed into the dry spinning duct via a metering pump. The spinneret assembly has 8 holes with a diameter of 80µm. The total extrusion rate of the modified polyurethane spinning solution is 8.5g / min. Dry hot air is introduced into the duct with an average axial wind speed of 0.8m / s. The temperature of the first section of the duct is 115℃. The evaporation rate of N,N-dimethylacetamide at the outlet of the first section is controlled to be 45% by controlling the hot air flow rate and the duct temperature. The evaporation rate of N,N-dimethylacetamide is calculated based on the unit time at the inlet of the first section. The difference between the mass of N,N-dimethylacetamide entering the filament and the mass of N,N-dimethylacetamide remaining in the first-section outlet filament was calculated as a percentage of the mass of N,N-dimethylacetamide entering the first-section inlet per unit time. The mass of N,N-dimethylacetamide remaining in the first-section outlet filament was determined by headspace gas chromatography. The temperature of the second section of the tunnel was 162℃, and the draw ratio was 2.2 times. The temperature of the third section of the tunnel was 208℃, the cumulative draw ratio was 3.2 times, and the winding speed was 680m / min, resulting in 40D modified polyurethane elastic fiber.

[0063] Step 6: 1000g of modified polyurethane elastic fiber is pre-stretched 3 times at 25℃ to serve as the core yarn, and 3000g of nylon 6 fully drawn yarn is used as the outer yarn. The nylon-coated modified polyurethane elastic fiber covered yarn is made with a covering twist of 800T / m, and then wound after being relaxed for 30s under 80℃ steam conditions.

[0064] Step 7: 4000g of nylon-coated modified polyurethane elastic fiber coated yarn is woven into a knitted fabric on a 32-needle / 25.4mm circular knitting machine. The loop length is 2600µm, the yarn tension is 4cN, and the fabric weight is 220g / m2. 2000g of knitted fabric is added to 40000g of water, 40g of fatty alcohol polyoxyethylene ether, and 20g of sodium carbonate. It is washed at 40℃ for 20min, then rinsed with clean water until the pH of the residual liquid on the fabric surface is 7. It is then centrifuged to remove water until the liquid content is 60%. Subsequently, it is heat-set at 165℃ for 45s with an overfeed rate of 5% and a width of 150cm to obtain a high-elasticity fiber fabric.

[0065] Comparative Example 1:

[0066] The difference from Example 1 is that steps two and three of Example 1 are not performed, and in step four, all the surface segment gradient modified prepolymer solution obtained in step three is not added. Instead, a matrix polyurethane spinning solution is prepared using the same method as in step one, and the total polyurethane solid mass is made up to the same as in Example 1 by the mass of polyurethane solids contained in the matrix polyurethane spinning solution. The total amount of N,N-dimethylacetamide is adjusted to be the same as in Example 1, and the other conditions are the same as in Example 1.

[0067] Comparative Example 2:

[0068] The difference from Example 1 is that step two is replaced by: adding 165.8g of polycarbonate diol with a number average molecular weight of 2000 and 120g of N,N-dimethylacetamide to a reactor, heating to 80°C under nitrogen protection and dehydrating for 60 min, cooling to 70°C, adding 49.9g of 4,4'-diphenylmethane diisocyanate and 200mg of bismuth isooctanoate polyurethane catalyst, reacting at 70°C for 90 min, then adding 8.3g of 1,4-butanediol and 40g of N,N-dimethylacetamide, reacting at 70°C for 60 min, to obtain a polycarbonate diol-type polyurethane prepolymer with a hard segment mass fraction of approximately 26% and an isocyanate group mass fraction of approximately 9.2‰; the remaining steps are the same as in Example 1.

[0069] Comparative Example 3:

[0070] The difference from Example 1 is that the polycarbonate diol-type high-hardness polyurethane prepolymer and surface modification components in steps two and three are reduced proportionally to the mass ratio in Example 1, so that the polycarbonate diol-type high-hardness polyurethane prepolymer accounts for 4.0% of the total solid mass of polyurethane by solid mass. Specifically, the composition is: 71.0 g of polycarbonate diol, 28.9 g of 4,4'-diphenylmethane diisocyanate, 6.2 g of 1,4-butanediol, 1.4 g of hydrophilic fumed silica, 0.9 g of hydrophobic fumed silica, 3.8 g of hydroxyalkyl-terminated polydimethylsiloxane, and 1.9 g of n-butanol; the total solid mass of polyurethane is supplemented with the matrix polyurethane spinning solution prepared in the same way as in step one, and the total amount of N,N-dimethylacetamide is adjusted to be the same as in Example 1, with the remaining conditions being the same as in Example 1.

[0071] Comparative Example 4:

[0072] The difference from Example 1 is that the 3g of hydrophilic fumed silica in step 3 is replaced with 3g of hydrophobic fumed silica, so that the total mass of fumed silica is kept at 5g, and the other conditions are the same as in Example 1.

[0073] Comparative Example 5:

[0074] The difference from Example 1 is that the 2g of hydrophobic fumed silica in step 3 is replaced with 2g of hydrophilic fumed silica, so that the total mass of fumed silica is kept at 5g, and the other conditions are the same as in Example 1.

[0075] Comparative Example 6:

[0076] The difference from Example 1 is that 8g of hydroxyalkyl-terminated polydimethylsiloxane in step 3 is replaced with 8g of polytetrahydrofurandiol, so that the mass of the hydroxyl compound added to the reaction system in step 3 remains unchanged, and the other conditions are the same as in Example 1.

[0077] Comparative Example 7:

[0078] The difference from Example 1 is that in step three, 2g of N,N-dimethylacetamide dispersion of hydrophobic fumed silica is first added to the polycarbonate diol type high-hardness polyurethane prepolymer obtained in step two, followed by 3g of hydrophilic fumed silica dispersion, and then 8g of hydroxyalkyl-terminated polydimethylsiloxane is added. The amount of each substance is kept the same as in Example 1, and the other conditions are the same as in Example 1.

[0079] Comparative Example 8:

[0080] The difference from Example 1 is as follows: In step three, after adding N,N-dimethylacetamide to the hydrophilic fumed silica, it was sheared at 1000 r / min for 5 min without ultrasonic dispersion, and the cumulative volume distribution of the hydrophilic fumed silica dispersion corresponds to a particle size of 1300 nm at 90%; after adding N,N-dimethylacetamide to the hydrophobic fumed silica, it was sheared at 1000 r / min for 5 min without ultrasonic dispersion, and the cumulative volume distribution of the system after adding hydrophobic fumed silica corresponds to a particle size of 1600 nm at 90%; the other conditions are the same as in Example 1.

[0081] Comparative Example 9:

[0082] The difference from Example 1 is that in step five, the amount of N,N-dimethylacetamide volatilized at the first outlet is controlled to be 25% by controlling the hot air flow rate and the tunnel temperature, while the other conditions are the same as in Example 1.

[0083] Comparative Example 10:

[0084] The difference from Example 1 is that in step five, the volatilization of N,N-dimethylacetamide at the first outlet is controlled to be 60% by controlling the hot air flow rate and the tunnel temperature, while the other conditions are the same as in Example 1.

[0085] Comparative Example 11:

[0086] The difference from Example 1 is that the stretching ratio of the second section of the tunnel in step five is 1, and the cumulative stretching ratio of the third section of the tunnel is 3. The other conditions are the same as in Example 1.

[0087] Performance testing:

[0088] The samples in Examples 1-4 and Comparative Examples 1-11 were prepared according to their respective described steps. The samples used for testing the intrinsic properties of the fibers were taken from the 40D modified polyurethane elastic fibers wound in step five of each example and comparative example; the samples used for observing the interfacial slippage of the covered yarn were taken from the nylon-covered modified polyurethane elastic fiber covered yarn prepared in step six of each example and comparative example; and the samples used for testing the fabric application performance were taken from the high-elasticity fiber fabric prepared in step seven of each example and comparative example. All fabric samples were conditioned for 24 hours in a standard atmosphere at 20°C and 65% relative humidity before cutting. The conditioning and testing environment were performed according to GB / T 6529-2008. At least three batches of samples were prepared for each example and comparative example. Samples from each batch were cut from the middle and both sides of the fabric width, and the test results were taken as the arithmetic mean.

[0089] Particle size corresponding to 90% cumulative volume distribution of the dispersion system: The hydrophilic fumed silica dispersions from Step 3 of Examples 1-4 and Comparative Examples 1-11, as well as the system after adding hydrophobic fumed silica, were used as test samples. Particle size was tested according to GB / T19077-2024. Before testing, the samples were allowed to stand at 25℃ for 30 min. Using N,N-dimethylacetamide as the dispersion medium, the samples were diluted to a laser particle size analyzer with an opacity of 8%-12%. The instrument's circulation pump speed was set to 1800 r / min, the ultrasonic power to 100 W, the ultrasonic time to 60 s, and the test temperature to 25℃. Each sample was tested three times consecutively, and the particle size corresponding to 90% cumulative volume distribution of the hydrophilic fumed silica dispersion (A) and the particle size corresponding to 90% cumulative volume distribution of the system after adding hydrophobic fumed silica (B) were recorded.

[0090] Distribution of surface chain segments in modified polyurethane elastic fibers: 40D modified polyurethane elastic fibers obtained in step five of Examples 1-4 and Comparative Examples 1-11 were analyzed by X-ray photoelectron spectroscopy according to GB / T 19500-2025, and infrared spectroscopy was performed in conjunction with GB / T6040-2019. X-ray photoelectron spectroscopy used a monochromatic Al Kα ray source with an energy of 1486.6 eV, an analysis spot diameter of 200 µm, and a pass energy of 20 eV. Charge correction was performed using the C1s peak at 284.8 eV. Argon ion beam sputtering was used, with a sputtering rate calibrated to 5 nm / min using a standard silica film. The peak areas of C1s, N1s, O1s, and Si2p at depths of 0 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, and 120 nm were recorded, and the nitrogen-carbon atomic ratio was calculated. The average nitrogen-carbon atomic ratio at a depth of 100-120 nm is taken as the core layer stability value. The continuous surface region with a nitrogen-carbon atomic ratio more than 10% higher than the core layer stability value is defined as the surface hard segment enrichment layer. When the critical position is located between two adjacent sputtering depth points, the thickness of the surface hard segment enrichment layer is calculated by linear interpolation using the nitrogen-carbon atomic ratio of the two adjacent depth points. The thickness of the surface hard segment enrichment layer and the surface / core nitrogen-carbon ratio are recorded.

[0091] Tensile and elastic recovery properties of modified polyurethane elastic fibers: 40D modified polyurethane elastic fibers obtained in step five of Examples 1-4 and Comparative Examples 1-11 were used. The fiber breaking strength and elongation at break were tested according to GB / T 14344-2022, and the elastic recovery properties were tested according to FZ / T 50007-2012. For the tensile test, the clamping distance was 50 mm, the tensile speed was 500 mm / min, and the pre-tension was 0.01 cN / dtex. Ten monofilaments were tested for each sample, and the breaking strength and elongation at break were recorded. For the elastic recovery test, a 300% constant elongation condition was used, with a clamping distance of 50 mm and a tensile speed of 500 mm / min. After stretching to 300% elongation, the elongation was held for 30 s, followed by 60 s recovery. This cycle was repeated 5 times, and the elastic recovery rate and stress retention rate were recorded after the 5th cycle.

[0092] Tensile elastic recovery rate of knitted fabrics: The high-elasticity fiber fabrics obtained in step seven of Examples 1-4 and Comparative Examples 1-11 were used to test the tensile elastic recovery rate of knitted fabrics using the constant elongation method according to FZ / T 70006-2022. Five samples were cut along the transverse direction for each sample, with an effective clamping length of 100 mm and a width of 50 mm; another five samples were cut along the longitudinal direction, with an effective clamping length of 100 mm and a width of 50 mm. The constant elongation rate of the transverse samples was 30%, and the constant elongation rate of the longitudinal samples was 20%. The stretching speed was 100 mm / min. After reaching the specified elongation, the sample was held for 30 seconds, unloaded, and allowed to recover for 60 seconds. This cycle was repeated five times. The transverse elastic recovery rate and transverse plastic deformation rate were recorded after the fifth cycle.

[0093] Dimensional change rate after washing and drying: The high-elasticity fiber fabrics obtained in step seven of Examples 1-4 and Comparative Examples 1-11 were used. Sample preparation, marking, and measurement were performed according to GB / T 8628-2013. Household washing and drying procedures were performed according to GB / T 8629-2017. Dimensional change rate after washing and drying was calculated according to GB / T 8630-2013. Three 500mm × 500mm samples were cut from each sample. Three sets of marking points were set in both the transverse and longitudinal directions of the samples, with a spacing of 350mm between the marking points. The washing procedure was a standard 40℃ washing program. The standard detergent dosage was added according to the washing program specifications, and the liquor ratio was controlled at 1:20. After each washing cycle, the samples were hung to dry. Ten consecutive washing and drying cycles were performed. After each cycle, the samples were conditioned for 4 hours in standard atmospheric conditions at 20℃ and 65% relative humidity. After the 10th cycle, the transverse marking point spacing was measured, and the transverse dimensional change rate was calculated.

[0094] Elastic recovery retention rate after sweat heat treatment: High-elasticity fiber fabrics obtained in step seven of Examples 1-4 and Comparative Examples 1-11 were used. First, acidic artificial sweat was prepared according to GB / T 3922-2013 and the fabric was soaked in the sweat. Then, the tensile elastic recovery rate of the treated knitted fabric was tested according to FZ / T70006-2022. Specifically, the fabric was cut into 200mm×200mm samples and immersed in acidic artificial sweat at a bath ratio of 1:50. The treatment temperature was 37℃, and the treatment time was 4 hours. After removal, the samples were quickly rinsed with deionized water for 30 seconds and allowed to equilibrate naturally for 24 hours in a standard atmosphere at 20℃ and 65% relative humidity. The transverse elastic recovery rate after treatment was then tested. The transverse elastic recovery rate of the same sample before sweat heat treatment was used as a benchmark to calculate the transverse elastic recovery retention rate after sweat heat treatment.

[0095] Core filament exposed length after constant stretching cycle: The nylon-coated modified polyurethane elastic fiber coated yarns prepared in step six of Examples 1-4 and Comparative Examples 1-11 were used. First, the coated yarns underwent cyclic stretching treatment according to the constant stretching cycle concept of FZ / T 70006-2022. Then, the core filament exposed length was statistically analyzed using a microscopic observation method. Specifically: 100m of coated yarn was taken for each sample, and a 30% constant stretching cycle was applied at 25℃ with a stretching speed of 100mm / min. After reaching the specified elongation, the length was held for 30s, unloaded, and returned to its original position for 60s. This cycle was repeated 1000 times. After the cycle, 50mm long samples were taken every 10m along the length of the coated yarn, for a total of 10 segments. These segments were observed under a stereomicroscope at 50x magnification. The length of the polyurethane elastic fiber core filament directly visible after detaching from the nylon outer fiber cover in each segment was recorded and converted into the core filament exposed length per 100m of coated yarn.

[0096] Bursting strength of knitted fabrics: The high-elasticity fiber fabrics obtained in step seven of Examples 1-4 and Comparative Examples 1-11 were used to determine the bursting strength using the steel ball method according to GB / T 19976-2005. Five circular specimens were cut for each sample, with a specimen diameter of 100 mm and a steel ball diameter of 25 mm. The bursting speed was 300 mm / min. The specimens were conditioned for 24 hours in standard atmosphere at 20°C and 65% relative humidity before testing, and the maximum bursting force was recorded.

[0097] Table 1 Performance Test Results

[0098] sample Surface hard segment enrichment layer thickness / nm Surface / core layer nitrogen-carbon ratio Particle size A / nm Particle size B / nm 300% constant elongation elastic recovery rate / % Lateral elastic recovery rate of knitted fabric / % Transverse dimensional change rate after 10 washes / % Horizontal elasticity recovery retention rate after sweat moist heat treatment / % Exposed length of core wire after constant stretching cycle / mm / 100m Breakthrough force / N Example 1 78 1.31 650 850 97.9 95.5 -1.4 96 14.2 416 Example 2 62 1.23 720 950 97.2 94.6 -1.8 94.5 21.6 397 Example 3 88 1.37 630 900 98.3 96.2 -0.9 97.2 7.8 439 Example 4 98 1.42 600 850 97.6 95.7 -1.1 96.7 10.5 432 Comparative Example 1 0 1.03 - - 95.1 89.1 -4.8 80.6 254.3 342 Comparative Example 2 42 1.14 665 875 96.2 91.7 -3.6 88.0 128.7 369 Comparative Example 3 36 1.12 680 905 95.8 90.8 -4.1 84.7 163.5 356 Comparative Example 4 54 1.19 840 1085 96.3 91.9 -3.3 86.4 146.2 381 Comparative Example 5 70 1.28 625 790 96.8 92.7 -3.8 83.5 111.4 392 Comparative Example 6 64 1.25 655 880 96.5 92.3 -3.4 87.2 125.6 374 Comparative Example 7 56 1.20 875 1060 95.9 91.4 -3.7 86.0 139.8 362 Comparative Example 8 40 1.15 1300 1600 94.7 89.8 -4.5 81.7 206.9 334 Comparative Example 9 46 1.16 650 850 95.6 90.6 -4.0 84.2 176.4 351 Comparative Example 10 112 1.46 650 850 93.8 87.9 -4.9 79.8 231.5 318 Comparative Example 11 60 1.22 650 850 95.4 90.4 -4.2 83.9 188.2 348

[0099] As shown in Table 1, Comparative Example 1, without the introduction of polycarbonate diol-type high-hardness polyurethane prepolymer, hydrophilic / hydrophobic fumed silica, and hydroxyalkyl-terminated polydimethylsiloxane, did not form a significant surface hardness enrichment layer in the modified polyurethane elastic fiber. Its surface / core nitrogen-carbon ratio was only 1.03, the transverse elastic recovery rate of the knitted fabric was 89.1%, the transverse dimensional change rate after 10 washes was -4.8%, the transverse elastic recovery retention rate after sweat heat treatment was 80.6%, and the exposed length of the core filament after constant stretching reached 254.3 mm / 100 m. This indicates that although conventional polyurethane elastic fiber can provide a certain tensile recovery capacity when used as the core filament, the interfacial stability between the core filament and the nylon outer fiber is insufficient after repeated constant stretching, washing, and sweat heat treatment.

[0100] Compared with Comparative Example 1, the thickness of the surface hard segment enrichment layer in Examples 1-4 was increased to 62-98 nm, the nitrogen-carbon ratio of the surface / core layer was increased to 1.23-1.42, the 300% constant elongation elastic recovery rate was increased to 97.2%-98.3%, the transverse elastic recovery rate of the knitted fabric was increased to 94.6%-96.2%, the absolute value of the transverse dimensional change rate after 10 washes was reduced to 0.9%-1.8%, the transverse elastic recovery retention rate after sweat heat treatment was increased to 94.5%-97.2%, the exposed length of the core filament after constant elongation cycling was reduced to 7.8-21.6 mm / 100 m, and the bursting strength was increased to 397-439 N. This indicates that the present invention, without changing the nylon coating ratio, coating twist, knitting density, and heat setting conditions, improves the elastic recovery, post-wash dimensional stability, and post-cycle coating stability of the fabric by controlling the composition of the surface chain segments and the dispersed phase state of the polyurethane elastic fiber. Example 3 showed the best overall performance, with a 300% constant stretch elastic recovery rate, a knitted fabric transverse elastic recovery rate, and a transverse elastic recovery retention rate after sweat and heat treatment reaching 98.3%, 96.2%, and 97.2%, respectively. After 10 washes, the transverse dimensional change rate was only -0.9%, and the exposed core filament length after constant stretching cycles was only 7.8 mm / 100 m.

[0101] Comparative Examples 2 and 3 show that when the mass fraction or addition ratio of hard segments in the polycarbonate diol-type high-hardness polyurethane prepolymer is insufficient, the thickness of the surface hard segment enrichment layer and the nitrogen-carbon ratio of the surface / core layer decrease, while the dimensional changes of the fabric after washing and the exposure of the core fibers both increase. Comparative Examples 4, 5, and 6 show that changing any one of the action units in hydrophilic fumed silica, hydrophobic fumed silica, or hydroxyalkyl-terminated polydimethylsiloxane alone cannot simultaneously maintain initial elasticity, moisture and heat retention, and cyclic coating stability. Comparative Examples 7 and 8 show that the addition order and dispersion particle size of the three types of action units have a significant impact on the surface segment distribution and interfacial stability. Comparative Examples 9, 10, and 11 show that when the volatilization amount of N,N-dimethylacetamide in the first segment and the segmented stretching window deviate from the appropriate range, even if the local surface hard segment signal increases, it is difficult to obtain stable overall performance.

[0102] In summary, this invention, through the synergistic control of polycarbonate diol-type high-hardness polyurethane prepolymer, hydrophilic / hydrophobic fumed silica, hydroxyalkyl-terminated polydimethylsiloxane, and the dry spinning coagulation and stretching window, enables modified polyurethane elastic fibers to maintain the elastic recovery ability of the core layer while improving the interfacial stability between the surface layer and the nylon outer fiber. This results in a high-elasticity fiber fabric with high elastic recovery rate, small dimensional change after washing, high performance retention after sweat and heat treatment, and minimal core fiber exposure after cycling.

[0103] 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 high-elasticity fiber fabric, characterized by, The product includes a knitted base fabric, which is woven from nylon-coated modified polyurethane elastic fiber coated yarn. The nylon-coated modified polyurethane elastic fiber coated yarn includes a modified polyurethane elastic fiber as the core yarn and nylon outer fibers covering the outside of the core yarn. The modified polyurethane elastic fiber includes a core elastic polyurethane phase and a surface hard segment enriched phase located outside the core elastic polyurethane phase. The modified polyurethane elastic fiber is formed from polyurethane solids comprising a matrix polyurethane and a polycarbonate diol-type high-hardness segment polyurethane prepolymer. The matrix polyurethane accounts for 90%-92% of the total mass of the polyurethane solids, with the remainder being the polycarbonate diol-type high-hardness segment polyurethane prepolymer. The surface hard segment enriched phase includes a phase structure formed by the polycarbonate diol type high hard segment polyurethane prepolymer, hydrophilic fumed silica, hydrophobic fumed silica and hydroxyalkyl-terminated polydimethylsiloxane. The polycarbonate diol-type high-hardness polyurethane prepolymer has a hard segment mass fraction of 32%-36% and an isocyanate group mass fraction of 8‰-12‰.

2. The high-elasticity fiber fabric according to claim 1, characterized by, The matrix polyurethane is formed by reacting 1800 parts by weight of polytetrahydrofuran diol, 550 parts by weight of 4,4'-diphenylmethane diisocyanate, 67 parts by weight of ethylenediamine and 12 parts by weight of diethylamine, wherein the number average molecular weight of the polytetrahydrofuran diol is 1800.

3. The high-elasticity fiber fabric according to claim 1, characterized by, The polycarbonate diol-type high-hardness polyurethane prepolymer is formed by reacting polycarbonate diol, 4,4'-diphenylmethane diisocyanate and 1,4-butanediol with a number average molecular weight of 1000-2000.

4. The high-elasticity fiber fabric according to claim 1, wherein The surface hard segment enriched phase is formed from the following raw materials in parts by weight: 145-170 parts of polycarbonate diol with a number average molecular weight of 1000-2000, 61.1-78.5 parts of 4,4'-diphenylmethane diisocyanate, 7.1-17.2 parts of 1,4-butanediol, 2.5-3.6 parts of hydrophilic fumed silica, 1.6-2.8 parts of hydrophobic fumed silica, and 6-10 parts of hydroxyalkyl-terminated polydimethylsiloxane.

5. The high-elasticity fiber fabric according to claim 1, wherein The surface hard segment enriched phase is formed by first introducing hydrophilic fumed silica into the polycarbonate diol-type high hard segment polyurethane prepolymer, then introducing hydrophobic fumed silica, and subsequently introducing hydroxyalkyl-terminated polydimethylsiloxane.

6. The high-elasticity fiber fabric according to claim 1, wherein The hydrophilic fumed silica has a specific surface area of 200 m 2 / g; the hydrophobic fumed silica is a hexamethyldisilazane post-treated hydrophobic fumed silica.

7. The high-elasticity fiber fabric according to claim 1, wherein The number average molecular weight of the hydroxyalkyl-terminated polydimethylsiloxane is 4000.

8. The high-elasticity fiber fabric according to claim 1, wherein In the nylon-coated modified polyurethane elastic fiber coated yarn, the mass ratio of the modified polyurethane elastic fiber to the nylon outer fiber is 1:

3.

9. A molding process for a high-elasticity fiber fabric as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparation of matrix polyurethane spinning solution: Polytetrahydrofuran diol and N,N-dimethylacetamide are mixed and dehydrated, and 4,4'-diphenylmethane diisocyanate is added to react and obtain an isocyanate-terminated matrix polyurethane prepolymer solution; ethylenediamine and diethylamine are dissolved in N,N-dimethylacetamide to form a chain extension and end-capping solution, and the chain extension and end-capping solution is added to the matrix polyurethane prepolymer solution to obtain the matrix polyurethane spinning solution; S2. Preparation of polycarbonate diol type high hardness segment polyurethane prepolymer: Polycarbonate diol with a number average molecular weight of 1000-2000 is mixed with N,N-dimethylacetamide and dehydrated. 4,4'-diphenylmethane diisocyanate and bismuth isooctanoate polyurethane catalyst are added and reacted. Then 1,4-butanediol and N,N-dimethylacetamide are added and reacted to obtain polycarbonate diol type high hardness segment polyurethane prepolymer. S3. Preparation of surface segment gradient modified prepolymer solution: Add hydrophilic fumed silica dispersion to the polycarbonate diol type high hardness polyurethane prepolymer obtained in step S2, then add hydrophobic fumed silica dispersion, then add hydroxyalkyl-terminated polydimethylsiloxane for reaction, then add n-butanol to continue the reaction, and obtain surface segment gradient modified prepolymer solution. S4. Preparation of modified polyurethane spinning solution: Add the surface segment gradient modified prepolymer solution obtained in step S3 to the matrix polyurethane spinning solution obtained in step S1, and then add antioxidant and N,N-dimethylacetamide. Mix, filter and degas to obtain modified polyurethane spinning solution. S5. Dry spinning: The modified polyurethane spinning solution obtained in step S4 is subjected to dry spinning. The amount of N,N-dimethylacetamide volatilized at the outlet of the first section of the dry spinning channel is controlled to be 35%-45%, the draw ratio of the second section of the channel is 1.8-2.2 times, and the cumulative draw ratio of the third section of the channel is 2.8-3.2 times, to obtain modified polyurethane elastic fibers. S6. Coating, weaving and finishing: Using the modified polyurethane elastic fiber obtained in step S5 as the core yarn and nylon 6 fully drawn yarn as the outer yarn, a nylon-coated modified polyurethane elastic fiber coated yarn is made. The nylon-coated modified polyurethane elastic fiber coated yarn is woven into a knitted fabric, and the knitted fabric is washed, rinsed, dehydrated and heat-set to obtain the high-elasticity fiber fabric.

10. The forming process of the high-elasticity fiber fabric according to claim 9, characterized by, In step S5, the modified polyurethane spinning solution is maintained at 45°C and fed into a dry spinning duct via a metering pump. The spinneret assembly has 8 holes with a diameter of 80µm. The total extrusion rate of the modified polyurethane spinning solution is 7.5-8.5g / min. Dry hot air is introduced into the duct with an average axial wind speed of 0.8m / s. The temperature of the first section of the duct is 108-115°C, the temperature of the second section is 158-162°C, and the temperature of the third section is 202-208°C. The winding speed is 620-680m / min, thereby obtaining modified polyurethane elastic fibers.