Spandex fiber for randomly cutting fabric as well as preparation method and application of spandex fiber

Abstract

The invention belongs to the technical field of fibers, and particularly relates to a spandex fiber for randomly tailoring a fabric and a preparation method and application of the spandex fiber. The spandex fiber is prepared from the following raw materials: isocyanate, modified polyol, a bifunctional compound and a compound additive. The spandex fiber for randomly cutting the fabric has excellent mechanical properties, the strength is 2.01-2.18 d / g, the stress at definite elongation is 13.0-13.7 cN, the elongation at break is 522-557%, efficient heat setting can be met at the temperature of 175 DEG C or below, and the heat setting efficiency is 87-92%; and after heat treatment, the strength is only reduced by about 2%, and the elongation at break is reduced by not more than 10%. The prepared spandex fiber has good adaptability, and when the spandex fiber is blended with cotton, silk, wool and other fibers with poor heat resistance, the fabric made of the spandex fiber has good dimensional stability during cutting, edge curling and thread loosening are avoided, and the spandex fiber can be cut at will.

Description

Technical Field

[0001] The invention belongs to the technical field of fibers, and in particular relates to a spandex fiber for randomly cutting fabrics, and a preparation method and application thereof. Background Art

[0002] Traditional textile and clothing design focuses on application and simplicity. With the continuous improvement and upgrading of consumers' quality of life and consumption concepts, textiles now show characteristics of health, comfort, beauty, fashion and functionality.

[0003] Free-cut fabrics are emerging fabrics in recent years. They are usually elastic fabrics made of chemical fiber and spandex. They have good cutting adaptability and edge stability, can be cut freely, and are not easy to curl. They have broad application prospects in the field of emerging fabric development. At present, the dimensional stability of the fabric cutting process is generally achieved to a certain extent through heat setting. Traditional spandex fibers require higher temperatures for heat setting. However, if spandex is blended with fibers with poor heat resistance such as cotton, silk, and wool, the conventional 190-195℃ is used for setting, which will seriously damage the dimensional and performance stability of cotton, silk, wool, etc. The fabrics made of it are prone to insufficient strength, curling, and de-threading during cutting, and the processability is greatly reduced; but if the setting temperature is lowered in order to protect the structure of cotton, silk, and wool, the internal stress cannot be completely eliminated, and its heat setting efficiency HSE will be significantly reduced.

[0004] Therefore, in order to obtain high-performance fabrics with dimensional stability, cutting freedom, and no curling, it is necessary to strictly control the temperature of heat setting, and even adjust the temperature according to the type of spandex blended fiber. It is impossible to use the same temperature, resulting in a waste of raw materials, time, and manpower. On the other hand, the strength of the free-cut fabric is also poor, which limits its practical application in the textile field.

[0005] Therefore, developing a spandex fiber that has high heat setting efficiency at low temperature and good strength so that the fabric blended with the spandex fiber has excellent cutting adaptability and edge stability has broad application prospects in the textile field. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a spandex fiber for randomly cutting fabrics and a preparation method and application thereof, so as to achieve the invention purpose of the fabric having good dimensional stability, high strength, not easy to curl or unravel, and can be randomly cut.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: The first part of the present invention provides a spandex fiber for randomly cutting fabrics. The raw materials used in the preparation of the spandex fiber include: isocyanate, modified polyol, bifunctional compound, and composite auxiliary agent.

[0008] Preferably, the molar ratio of the isocyanate to the modified polyol is 1.8-2:1.

[0009] Preferably, the isocyanate includes one or more of a symmetric isocyanate and an asymmetric isocyanate.

[0010] Further, the symmetric isocyanate is selected from one or more of 4,4'-diphenylmethane diisocyanate, 2,2'-bis(4-isobutylisopentyl)propane, and 3,5'-diethyl-4-isobutylisopentylmethane.

[0011] Further, the asymmetric isocyanate is selected from one or more of 2,4-diphenylmethane diisocyanate, isophorone diisocyanate, and 1,4-phenylene diisocyanate.

[0012] More preferably, the isocyanate is 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 3:7.

[0013] Preferably, the preparation method of the modified polyol is as follows: S11. Activation Add dipropylene glycol to chloroform, then add triethylamine and p-toluenesulfonyl chloride, and react at 0-5°C for 12-16 h so that one terminal hydroxyl group of dipropylene glycol is replaced by a p-toluenesulfonate group. After the reaction, add 1 mol / L hydrochloric acid solution to the reaction solution to extract the organic phase. Add excessive anhydrous sodium carbonate to the organic phase, stir well and then filter. Add the filtrate to excessive anhydrous ether, stir well to precipitate a white solid, filter by suction and dry to obtain activated dipropylene glycol.

[0014] S12. Modification with silane Add activated dipropylene glycol to DMSO, then add potassium trimethylsilanolate, and carry out a nucleophilic substitution reaction at room temperature for 8-10 h. After the reaction, centrifuge to take the supernatant and concentrate it under reduced pressure to obtain a crude product. The crude product is obtained as a dipropylene glycol-silane product after extraction and drying with anhydrous sodium sulfate.

[0015] S13. Modification with pyridine Add the dipropylene glycol-silane product to DMSO, then add 2-pyridyl dithiocarbonate and potassium carbonate, and react at 40-50°C for 6-8 h to graft a pyridine group onto the other terminal hydroxyl group of the dipropylene glycol-silane product. After the reaction, centrifuge to take the supernatant and concentrate it under reduced pressure to obtain a crude product. The crude product is obtained as a modified polyol containing a silyl group and a pyridine group after extraction, drying with anhydrous sodium sulfate, and distillation under reduced pressure.

[0016] Preferably, in S11, the molar ratio of dipropylene glycol to p-toluenesulfonyl chloride is 1:2-2.4.

[0017] Preferably, in S11, triethylamine is used as a basic catalyst, and the addition amount is 1-2% of the mass of dipropylene triol.

[0018] Preferably, in S12, the addition amount of potassium trimethylsilanolate is 20-30% of the mass of activated dipropylene triol.

[0019] Preferably, in S13, the addition amount of 2-pyridyldithiocarbonate is 23-28% of the mass of the dipropylene triol-silane product.

[0020] Preferably, in S13, the addition amount of potassium carbonate is to adjust the pH of the reaction system to 8-9.

[0021] The distribution ratio of the hard and soft segments of spandex has a direct impact on its setting temperature. The applicant unexpectedly found that when using 2,2'-bis(4-isobutylisopentyl)propane, 2,4-diphenylmethane diisocyanate and modified polyol with a molar ratio of 3:7, it makes the spandex molecules have a specific hard and soft segment distribution ratio: (1) 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate can introduce a certain proportion of rigid structures into the molecular structure of spandex. While ensuring the definite elongation stress and heat resistance of spandex, the steric effect is used to reduce the crystallinity of the hard segments in the spandex molecular structure, reduce the restrictive effect of the hard segments on the soft segment molecular chains, and improve the heat setting efficiency of spandex to a certain extent; (2) Dipropylene triol contains four hydroxyl groups. After modification, one terminal hydroxyl group is grafted with a silyl group and one terminal hydroxyl group is grafted with a pyridine group. The modified polyol is used as the soft segment of the spandex molecular chain. The nitrogen atom on the pyridine ring has a high electronegativity, resulting in a low electron cloud density, so that the intermolecular force between pyridine molecules and the molecular chain is low, thereby reducing the molecular crystallinity and comprehensively improving the heat setting efficiency of spandex and improving the dimensional stability during the fabric cutting process.

[0022] Preferably, the difunctional compound is one or more of 2-methyl-1,5-pentanediamine, 1,4-cyclohexanediol, neopentyl glycol, diethanolamine, 3,5-dimethylthiotoluenediamine.

[0023] More preferably, the difunctional group is 2-methyl-1,5-pentanediamine, and the molar fraction is 40-50% of the total amount of isocyanate and modified polyol.

[0024] The higher the crystallinity of the hard segment of the spandex molecule, the more heat is required for the melt recrystallization process of the crystalline zone, and the setting effect is not good at a lower temperature. The hard segment structure formed by the reaction of 2-methyl-1,5-pentanediamine with 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate in a molar ratio of 3:7 in this scheme has reduced inter-molecular chain forces and is not easy to form an interlaced hydrogen bond network structure, resulting in low crystallinity of the hard segment. High-efficiency heat setting can be achieved under low temperature conditions. When it is blended with fibers with poor heat resistance such as cotton, silk, and wool, the fabric made of it has good dimensional stability, no curling, no debonding, and can be cut at will.

[0025] Preferably, the composite auxiliary agent is one or more of sodium benzoate, nano-silicon dioxide, and nano-calcium carbonate; the added amount of the composite auxiliary agent is 1 to 1.5% of the total mass of the spandex raw material.

[0026] Preferably, the composite auxiliary agent is nano-silicon dioxide and nano-calcium carbonate in a mass ratio of 3:1.5; the particle size of the nano-silicon dioxide and nano-calcium carbonate is 50-100 nm.

[0027] The applicant has found that when the above-mentioned isocyanate and 2-methyl-1,5-pentanediamine are used, the setting temperature is reduced by reducing the crystallinity of the hard segment in the spandex molecular chain, but the strength of the spandex will decrease due to the reduced crystallinity. A silane group is connected to one end of the modified polyol. When a certain amount of nano-silicon dioxide and nano-calcium carbonate with a mass ratio of 3:1.5 is added to the scheme of the present invention, the surfaces of the nano-silicon dioxide and nano-calcium carbonate contain hydroxyl groups, which can react with the silane groups on the surface of the modified polyol to form crosslinking points, thereby improving the strength and thermal stability of the spandex to a certain extent, and making the fabric have excellent cutting adaptability and edge stability.

[0028] The second part of the present invention provides a method for preparing spandex fiber for randomly cutting fabrics: S21: After the modified polyol is dehydrated under reduced pressure at 115-125°C for 2-3 hours, a composite auxiliary agent is added and stirred evenly, the temperature is lowered to 80-85°C, isocyanate is added, stirred sufficiently, and then dibutyltin dilaurate is added, reacted for 2-3 hours, cooled for 60-80 minutes, and a prepolymer is obtained; S22: dissolving the prepolymer described in S21 in DMF to prepare a 20% concentration solution, adding a bifunctional compound, reacting at 30-35° C. for 2-3 hours, and obtaining a spinning solution with a viscosity of 3000-4000 poise (40° C.) through aging, filtering, and degassing; S23: The spinning solution in S22 is metered by a metering pump, extruded from a spinneret, and then enters a spinning tunnel to evaporate the solvent under heat and solidify into a filament bundle, which is then stretched, oiled, and heat-set to obtain the spandex fiber.

[0029] Preferably, the addition amount of dibutyltin dilaurate in S21 is 0.08-0.12% of the total mass of the raw materials.

[0030] Preferably, the curing temperature in S22 is 50-70 °C and the time is 12-24 h.

[0031] Preferably, the temperature of the spinning channel in S23 is 230-270 °C and the speed is 700-800 m / min.

[0032] Preferably, the draw ratio in S23 is 2-3 times.

[0033] Preferably, the temperature of heat setting in S23 is 170-175 °C and the time is 40-50 s.

[0034] The third part of the present invention provides an application of spandex fiber for arbitrarily cutting fabrics, and the application can be applied to the clothing field, especially skin-friendly clothes and home clothes.

[0035] Due to the adoption of the above technical solutions, the technical effects achieved by the present invention are as follows: 1. The spandex fiber for arbitrarily cutting fabrics prepared by the present invention has excellent mechanical properties, wherein the strength is 2.01-2.18 d / g, the fixed elongation stress is 13.0-13.7 cN, the elongation at break is 522-557%, and the heat setting efficiency is 87-92%.

[0036] 2. The spandex prepared by the present invention can achieve efficient heat setting below 175 °C. On the one hand, it can optimize the elasticity of the fabric, making the elasticity more durable and stable, and not easily deformed after multiple stretches, meeting the personalized needs of random cutting; on the other hand, it enhances the dimensional stability of the fabric, preventing the fabric from deforming due to the release of internal stress in the spandex after cutting, ensuring that the shape after cutting meets the expectations; and it has good adaptability. When blended with fibers with poor heat resistance such as cotton, silk, and wool, the fabric made of it has good dimensional stability during cutting, does not curl or thread, and can be arbitrarily cut.

[0037] 3. The spandex prepared by the present invention has good thermal stability. After heat treatment, the strength only decreases by about 2%, and the elongation at break decreases by no more than 10%. Detailed Embodiments

[0038] The following combines specific embodiments to further elaborate the present invention.

[0039] Example 1: A spandex fiber for arbitrarily cutting fabrics, and the raw materials used for preparing the spandex fiber include: isocyanate, modified polyol, bifunctional compound, and composite auxiliary.

[0040] The molar ratio of the isocyanate to the modified polyol is 1.9:1.

[0041] The isocyanate is 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 3:7.

[0042] The preparation method of the modified polyol is as follows: S11. Activation Add dipropylene glycol to chloroform, then add triethylamine and p-toluenesulfonyl chloride, and react at 3°C for 14 h to replace one terminal hydroxyl group of dipropylene glycol with a p-toluenesulfonate group. After the reaction, add 1 mol / L hydrochloric acid solution to the reaction solution to extract the organic phase. Add excessive anhydrous sodium carbonate to the organic phase, stir well and then filter. Add the filtrate to excessive anhydrous ether, stir well to precipitate white precipitate, and obtain activated dipropylene glycol after suction filtration and drying.

[0043] S12. Modification with silane Add activated dipropylene glycol to DMSO, then add potassium trimethylsilanolate, and carry out nucleophilic substitution reaction at room temperature for 9 h. After the reaction, centrifuge to take the supernatant and concentrate it under reduced pressure to obtain a crude product. The crude product is obtained as a dipropylene glycol-silane product after extraction and drying with anhydrous sodium sulfate.

[0044] S13. Modification with pyridine Add the dipropylene glycol-silane product to DMSO, then add 2-pyridyldithiocarbonate and potassium carbonate, and react at 45°C for 7 h to graft a pyridine group onto the other terminal hydroxyl group of the dipropylene glycol-silane product. After the reaction, centrifuge to take the supernatant and concentrate it under reduced pressure to obtain a crude product. The crude product is obtained as a modified polyol containing silane groups and pyridine groups after extraction, drying with anhydrous sodium sulfate, and distillation under reduced pressure.

[0045] In S11, the molar ratio of dipropylene glycol to p-toluenesulfonyl chloride is 1:2.2.

[0046] In S11, triethylamine is a basic catalyst, and the addition amount is 1.5% of the mass of dipropylene glycol.

[0047] In S12, the addition amount of potassium trimethylsilanolate is 25% of the mass of activated dipropylene glycol.

[0048] In S13, the addition amount of 2-pyridyldithiocarbonate is 26% of the mass of the dipropylene glycol-silane product.

[0049] In S13, the addition amount of potassium carbonate is to adjust the pH of the reaction system to 8.5.

[0050] The bifunctional compound is 2-methyl-1,5-pentanediamine, and the molar fraction is 45% of the total amount of the isocyanate and the modified polyol.

[0051] The composite auxiliary agent is nano-silica and nano-calcium carbonate with a mass ratio of 3:1.5; the particle sizes of the nano-silica and nano-calcium carbonate are 50 nm.

[0052] The addition amount of the composite auxiliary agent is 1.2% of the total mass of the spandex raw materials.

[0053] The second part of the present invention provides a preparation method of spandex fiber for arbitrarily cutting fabrics: S21: After the modified polyol is dehydrated under reduced pressure at 120 °C for 2 h, the composite auxiliary agent is added and stirred evenly. When the temperature drops to 80 °C, isocyanate is added, and after sufficient stirring, dibutyltin dilaurate is added, and the reaction is carried out for 2.5 h, and then cooled for 70 min to obtain a prepolymer; S22: The prepolymer described in S21 is dissolved in DMF to prepare a solution with a concentration of 20%, a bifunctional compound is added, and the reaction is carried out at 32 °C for 2.5 h. After curing, filtering, and degassing, a spinning dope with a viscosity of 3600 poise (40 °C) is obtained; S23: The spinning dope described in S22 is metered by a metering pump, extruded from the spinneret holes, enters the spinning channel, and then the heat solvent evaporates and solidifies into a filament bundle. After stretching, oiling, and heat setting, the spandex fiber is obtained.

[0054] The addition amount of dibutyltin dilaurate in S21 is 0.1% of the total mass of the raw materials.

[0055] The curing temperature in S22 is 60 °C and the time is 20 h.

[0056] The temperature of the spinning channel in S23 is 250 °C and the rate is 750 m / min.

[0057] The draw ratio in S23 is 2.5 times.

[0058] The heat setting temperature in S23 is 170 °C and the time is 50 s.

[0059] Example 2: A spandex fiber for arbitrarily cutting fabrics, the raw materials used in the preparation of the spandex fiber include: isocyanate, modified polyol, bifunctional compound, composite auxiliary agent.

[0060] The molar ratio of the isocyanate to the modified polyol is 2:1.

[0061] The isocyanate is 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 3:7.

[0062] The preparation method of the modified polyol is: S11. Activation Add dipropylene glycol to chloroform, then add triethylamine and p-toluenesulfonyl chloride, and react at 0 °C for 12 h so that one terminal hydroxyl group of dipropylene glycol is replaced by a p-toluenesulfonate group. After the reaction, add 1 mol / L hydrochloric acid solution to the reaction solution to extract the organic phase. Add excessive anhydrous sodium carbonate to the organic phase, stir well and then filter. Add the filtrate to excessive anhydrous ether, stir well to precipitate a white solid, and obtain activated dipropylene glycol after suction filtration and drying.

[0063] S12. Modification of silane Add the activated dipropylene glycol to DMSO, then add potassium trimethylsilanolate, and carry out a nucleophilic substitution reaction at room temperature for 8 h. After the reaction, centrifuge to take the supernatant and concentrate it under reduced pressure to obtain a crude product. The crude product is obtained as a dipropylene glycol-silane product after extraction and drying with anhydrous sodium sulfate.

[0064] S13. Modification of pyridine Add the dipropylene glycol-silane product to DMSO, then add 2-pyridyl dithiocarbonate and potassium carbonate, and react at 40 °C for 6 h to graft a pyridine group onto the other terminal hydroxyl group of the dipropylene glycol-silane product. After the reaction, centrifuge to take the supernatant and concentrate it under reduced pressure to obtain a crude product. The crude product is obtained as a modified polyol containing a silyl group and a pyridine group after extraction, drying with anhydrous sodium sulfate, and distillation under reduced pressure.

[0065] In S11, the molar ratio of dipropylene glycol to p-toluenesulfonyl chloride is 1:2.

[0066] In S11, triethylamine is a basic catalyst, and the addition amount is 1% of the mass of dipropylene glycol.

[0067] In S12, the addition amount of potassium trimethylsilanolate is 20% of the mass of the activated dipropylene glycol.

[0068] In S13, the addition amount of 2-pyridyl dithiocarbonate is 23% of the mass of the dipropylene glycol-silane product.

[0069] In S13, the addition amount of potassium carbonate is to adjust the pH of the reaction system to 8.

[0070] The bifunctional group is 2-methyl-1,5-pentanediamine, and the mole fraction is 40% of the total amount of isocyanate and modified polyol.

[0071] The composite auxiliary agent is nano-silica and nano-calcium carbonate with a mass ratio of 3:1.5; the particle sizes of the nano-silica and nano-calcium carbonate are 100 nm.

[0072] The addition amount of the composite auxiliary agent is 1% of the total mass of the spandex raw materials.

[0073] The preparation method of the spandex fiber for arbitrarily cuttable fabric is as follows: S21: After the modified polyol is dehydrated under reduced pressure at 115 °C for 3 h, a compound additive is added and stirred evenly. After the temperature drops to 85 °C, isocyanate is added and stirred thoroughly. Then dibutyltin dilaurate is added and the reaction is carried out for 2 h, followed by cooling for 60 min to obtain a prepolymer; S22: The prepolymer described in S21 is dissolved in DMF to prepare a solution with a concentration of 20%. A bifunctional compound is added and the reaction is carried out at 30 °C for 3 h. After aging, filtering, and defoaming, a spinning dope with a viscosity of 3000 poise (40 °C) is obtained; S23: The spinning dope described in S22 is metered by a metering pump, extruded from a spinneret hole, enters a spinning duct, and the solvent evaporates under heat to solidify into a filament bundle. After stretching, oiling, and heat setting, the spandex fiber is obtained.

[0074] The addition amount of dibutyltin dilaurate in S21 is 0.08% of the total mass of the raw materials.

[0075] The aging temperature in S22 is 50 °C and the time is 12 h.

[0076] The temperature of the spinning duct in S23 is 230 °C and the speed is 700 m / min.

[0077] The draw ratio in S23 is 3 times.

[0078] The heat setting temperature in S23 is 170 °C and the time is 40 s.

[0079] Example 3: A spandex fiber for a fabric that can be cut arbitrarily. The raw materials used for preparing the spandex fiber include: isocyanate, modified polyol, bifunctional compound, and compound additive.

[0080] The molar ratio of the isocyanate to the modified polyol is 1.8:1.

[0081] The isocyanate is 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 3:7.

[0082] The preparation method of the modified polyol is as follows: S11. Activation Dipropylene glycol is added to chloroform, and then triethylamine and p-toluenesulfonyl chloride are added. The reaction is carried out at 5 °C for 16 h so that one terminal hydroxyl group of dipropylene glycol is replaced by a p-toluenesulfonate group. After the reaction is completed, a 1 mol / L hydrochloric acid solution is added to the reaction solution to extract the organic phase. Excess anhydrous sodium carbonate is added to the organic phase, and after thorough stirring, filtration is carried out. The filtrate is added to excess anhydrous ether, and after thorough stirring, a white precipitate is precipitated. After suction filtration and drying, activated dipropylene glycol is obtained.

[0083] S12. Modification of silane Add the activated dipropylene glycol into DMSO, then add potassium trimethylsilanolate, and conduct a nucleophilic substitution reaction at room temperature for 10 h. After the reaction is completed, centrifuge to obtain the supernatant, and concentrate it under reduced pressure to obtain the crude product. The crude product is obtained as a dipropylene glycol-silane product after extraction and drying with anhydrous sodium sulfate.

[0084] S13. Modification of pyridine Add the dipropylene glycol-silane product into DMSO, then add 2-pyridyl dithiocarbonate and potassium carbonate, and react at 50 °C for 8 h to graft a pyridine group onto the other terminal hydroxyl group of the dipropylene glycol-silane product. After the reaction is completed, centrifuge to obtain the supernatant, and concentrate it under reduced pressure to obtain the crude product. The crude product is obtained as a modified polyol containing a silyl group and a pyridine group after extraction, drying with anhydrous sodium sulfate, and distillation under reduced pressure.

[0085] In S11, the molar ratio of dipropylene glycol to p-toluenesulfonyl chloride is 1:2.4.

[0086] In S11, triethylamine is used as a basic catalyst, and the addition amount is 2% of the mass of dipropylene glycol.

[0087] In S12, the addition amount of potassium trimethylsilanolate is 30% of the mass of the activated dipropylene glycol.

[0088] In S13, the addition amount of 2-pyridyl dithiocarbonate is 28% of the mass of the dipropylene glycol-silane product.

[0089] In S13, the addition amount of potassium carbonate is to adjust the pH of the reaction system to 9.

[0090] The bifunctional group is 2-methyl-1,5-pentanediamine, and the molar fraction is 50% of the total amount of isocyanate and modified polyol.

[0091] The composite auxiliary agent is nano-silica and nano-calcium carbonate with a mass ratio of 3:1.5; the particle sizes of the nano-silica and nano-calcium carbonate are 80 nm.

[0092] The addition amount of the composite auxiliary agent is 1.5% of the total mass of the spandex raw materials.

[0093] The preparation method of the spandex fiber for arbitrarily cuttable fabric is as follows: S21: After the modified polyol is dehydrated under reduced pressure at 125 °C for 2.5 h, add the composite auxiliary agent and stir evenly. When the temperature drops to 80 °C, add isocyanate, stir well, then add dibutyltin dilaurate, react for 3 h, and cool for 80 min to obtain a prepolymer; S22: Dissolve the prepolymer described in S21 in DMF to prepare a solution with a concentration of 20%. Add a bifunctional compound and react at 35 °C for 2 h. After curing, filtration, and degassing, a spinning dope with a viscosity of 4000 poise (40 °C) is obtained. S23: Meter the spinning dope described in S22 with a metering pump. After extruding from the spinneret holes and entering the spinning duct, the hot solvent evaporates and solidifies into a filament bundle. After drawing, oiling, and heat setting, the spandex fiber is obtained.

[0094] The addition amount of dibutyltin dilaurate in S21 is 0.12% of the total mass of the raw materials.

[0095] The curing temperature in S22 is 70 °C and the time is 12 h.

[0096] The temperature of the spinning duct in S23 is 270 °C and the rate is 800 m / min.

[0097] The draw ratio in S23 is 2 times.

[0098] The heat setting temperature in S23 is 175 °C and the time is 45 s.

[0099] Comparative Example 1: The difference between this example and Example 1 is that the isocyanate is 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 1:1, and the rest are the same as in Example 1, which is used as Comparative Example 1.

[0100] Comparative Example 2: The difference between this example and Example 1 is that the isocyanate is 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 2:6, and the rest are the same as in Example 1, which is used as Comparative Example 2.

[0101] Comparative Example 3 Select the representative Example 1. Only modify the pyridine group on the dipropylene glycol without modifying the silane, as the modified polyol, and the rest are the same as in Example 1, which is used as Comparative Example 3.

[0102] Comparative Example 4 Select the representative Example 1. Only modify the silane group on the dipropylene glycol without modifying the pyridine group, as the modified polyol, and the rest are the same as in Example 1, which is used as Comparative Example 4.

[0103] Perform performance testing on the spandex fibers prepared in the examples and comparative examples. After heat treatment at 140 °C for two hours, test their strength decline rate and elongation at break decline amount. The specific results are shown in Table 1.

[0104] Table 1 As can be seen from Table 1, while Examples 1-3 have excellent mechanical properties, they also have good heat setting efficiency and thermal stability. In Comparative Example 1 and Comparative Example 2, different molar ratios of isocyanate were used, and all properties decreased slightly, indicating that 2,2'-bis(4-isobutylisopentyl)propane and 2,4-diphenylmethane diisocyanate with a molar ratio of 3:7 can provide better mechanical properties, heat resistance, and heat setting efficiency; Comparative Example 3 shows that chemical cross-linking occurs between the silyl groups on the modified polyol and the hydroxyl groups on the surface of the composite additive, so the mechanical properties and thermal stability are better; Comparative Example 4 shows that the modified polyol modified with pyridine groups can improve the heat setting efficiency of the fiber, reduce the heat setting temperature, and also meet the blending processing effect with wool, silk, etc. with poor heat resistance.

[0105] Unless otherwise specified, the ratios described in the present invention are all mass ratios, and the percentages are all mass percentages; the raw materials are all commercially available.

[0106] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An spandex fiber for arbitrarily cutting fabrics, characterized in that, The raw materials used in the preparation of the spandex fiber include: isocyanate, modified polyol, bifunctional compound, and composite auxiliary agent; The modified polyol contains a silyl group and a pyridine group.

2. An spandex fiber for randomly cutting fabrics according to claim 1, characterized in that, The molar ratio of the isocyanate to the modified polyol is 1.8 - 2:1; The isocyanate includes one or more of symmetric isocyanate and asymmetric isocyanate; The symmetric isocyanate is selected from one or more of 4,4'-diphenylmethane diisocyanate, 2,2'-bis(4-isobutyl isopentyl) propane, and 3,5'-diethyl-4-isobutyl isopentyl methane; The asymmetric isocyanate is selected from one or more of 2,4-diphenylmethane diisocyanate, isophorone diisocyanate, and 1,4-phenylene diisocyanate.

3. An elastane fiber for arbitrarily cutting fabrics according to claim 1, characterized in that, The preparation method of the modified polyol includes activation, modification with silane, and modification with pyridine.

4. An spandex fiber for arbitrarily cutting fabrics according to claim 3, characterized in that, The activation is as follows: Add dipropylene glycol to chloroform, then add triethylamine and p-toluenesulfonyl chloride, and react at 0 - 5°C for 12 - 16 h. After the reaction is completed, add 1 mol / L hydrochloric acid solution to the reaction solution to extract the organic phase. Add excessive anhydrous sodium carbonate to the organic phase, stir well and then filter. Add the filtrate to excessive anhydrous ether, stir well to precipitate a white precipitate, filter by suction and dry to obtain activated dipropylene glycol; The molar ratio of the dipropylene glycol to the p-toluenesulfonyl chloride is 1:2 - 2.4; The triethylamine is a basic catalyst, and the addition amount is 1 - 2% of the mass of the dipropylene glycol.

5. An spandex fiber for arbitrarily cutting fabrics according to claim 3, characterized in that, The modification with silane is as follows: Add the activated dipropylene glycol to DMSO, then add potassium trimethylsilanolate, and carry out a nucleophilic substitution reaction at room temperature for 8 - 10 h. After the reaction is completed, centrifuge and take the supernatant for concentration under reduced pressure to obtain a crude product. The crude product is extracted, dried with anhydrous sodium sulfate to obtain a dipropylene glycol-silane product; The addition amount of the potassium trimethylsilanolate is 20 - 30% of the mass of the activated dipropylene glycol.

6. An elastane fiber for arbitrarily cutting fabrics according to claim 3, characterized in that, The modification with pyridine is as follows: Add the dipropylene glycol-silane product to DMSO, then add 2-pyridyl dithiocarbonate and potassium carbonate, and react at 40 - 50°C for 6 - 8 h. After the reaction is completed, centrifuge and take the supernatant for concentration under reduced pressure to obtain a crude product. The crude product is extracted, dried with anhydrous sodium sulfate, and distilled under reduced pressure to obtain a modified polyol containing a silyl group and a pyridine group; In S13, the addition amount of the 2-pyridyl dithiocarbonate is 23 - 28% of the mass of the dipropylene glycol-silane product; In S13, the addition amount of the potassium carbonate is to adjust the pH of the reaction system to 8 - 9.

7. The spandex fiber for arbitrarily cuttable fabric according to claim 1, characterized in that The bifunctional compound is one or more of 2-methyl-1,5-pentanediamine, 1,4-cyclohexanediol, neopentyl glycol, diethanolamine, and 3,5-dimethylthiotoluenediamine.

8. The spandex fiber for arbitrarily cuttable fabric according to claim 1, characterized in that The composite auxiliary agent is one or more of sodium benzoate, nano-silica, and nano-calcium carbonate; the addition amount of the composite auxiliary agent is 1 - 1.5% of the total mass of the spandex raw materials.

9. A preparation method of spandex fiber for arbitrarily cutting fabrics, characterized in that, The preparation method includes the following steps: S21: After the modified polyol is dehydrated under reduced pressure at 115 - 125°C for 2 - 3 hours, a composite auxiliary agent is added and stirred evenly. When the temperature drops to 80 - 85°C, isocyanate is added, and after sufficient stirring, dibutyltin dilaurate is added, and the reaction proceeds for 2 - 3 hours. After cooling for 60 - 80 minutes, a prepolymer is obtained; S22: The prepolymer described in S21 is dissolved in DMF to form a solution with a concentration of 20%. A bifunctional compound is added, and the reaction proceeds at 30 - 35°C for 2 - 3 hours. After curing, filtration, and degassing, a spinning dope with a viscosity of 3000 - 4000 poise (40°C) is obtained; S23: The spinning dope described in S22 is metered by a metering pump, extruded from a spinneret hole, enters a spinning channel, and the solvent evaporates under heat to solidify into a filament bundle. After drawing, oiling, and heat setting, the spandex fiber is obtained; In S21, the addition amount of dibutyltin dilaurate accounts for 0.08 - 0.12% of the total mass of the raw materials; In S23, the temperature of heat setting is 170 - 175°C, and the time is 40 - 50 s.

10. An spandex fiber for randomly cutting fabrics prepared by the preparation method of claim 9, characterized in that, The application of the spandex fiber is that it can be applied to the clothing field, especially close-fitting clothes and home clothes.

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