Low-temperature easy-setting composite spandex and preparation method thereof

Abstract

The application is a low-temperature easy-setting composite spandex and a preparation method thereof. The low-temperature easy-setting composite spandex comprises polyvinyl acetal and polyurethane-urea as two main components. The preparation method is to uniformly mix polyvinyl acetal and polyurethane-urea by solution blending, and then to spin the composite spandex by using dry spinning technology. The addition of polyvinyl acetal can effectively reduce the internal phase separation degree of spandex, weaken the intermolecular force, make the molecular chain quickly dissociate and rearrange under lower energy conditions, and realize efficient setting of spandex. In addition, the microcrystalline structure formed by polyvinyl acetal can act as a physical crosslinking point inside the fiber, and the original mechanical strength and elasticity of the spandex fiber can be maximally retained. The setting efficiency of the composite spandex bare yarn prepared by the application can reach 70% at 120-140 DEG C, and the setting effect of the ammonia-containing fabric mixed with polylactic acid fiber and polyethylene fiber is excellent, and the shrinkage rate is lower than 3.0%.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of elastic fibers, and particularly relates to a low-temperature easy-setting composite spandex and a preparation method thereof. BACKGROUND

[0002] As a kind of fiber material with high elasticity, spandex is generally used in combination with other fibers, and the proportion of spandex is generally not more than 10%, which can give the spandex-containing fabric certain stretch and resilience. Most of the fabrics need to go through the heat setting process in the processing process to eliminate fabric creases and deformation, and to improve the fabric hand and dimensional stability. Different fibers require different setting temperatures, such as the setting temperature of polyester is 180-200℃, the setting temperature of spandex is 180-195℃, the setting temperature of nylon is 160-180℃, the setting temperature of acrylic is 140-160℃, the setting temperature of polylactic acid fiber is 130-140℃, and the setting temperature of polypropylene fiber is 120-130℃. Since the setting temperatures of the component fibers of polyester / spandex and nylon / spandex fabrics are similar, good setting effect can be achieved at a relatively high temperature. However, for fabrics with component fibers having a large difference in setting temperature, such as polylactic acid / spandex fabric and polyethylene / spandex fabric, spandex with a setting temperature close to that of the main component fiber of the fabric needs to be used in the weaving process, such as spandex that can be set at 130-140 degrees. This functional spandex with a setting temperature much lower than that of conventional spandex is called low-temperature easy-setting spandex.

[0003] At present, the development and research of low-temperature easy-setting spandex is mostly through changing the hard segment composition of spandex, reducing the arrangement regularity and crystallization degree of the hard segment, so as to reduce the restriction of hard segment crystallization on molecular chain segments, so that the molecular chain segments of spandex can be quickly relaxed and rearranged under lower energy conditions, and good setting effect can be achieved. For example, using non-symmetrical diisocyanate instead of symmetrical diphenyl methane diisocyanate (patent CN101849048A), using non-symmetrical amine chain extender or alcohol chain extender instead of highly symmetrical chain extender (patent CN1176967A), etc. However, the change of hard segment composition will greatly affect the mechanical properties and heat resistance of spandex. SUMMARY

[0004] Technical problem: In view of the deficiencies in the prior art, the application provides a low-temperature easy-setting composite spandex and a preparation method thereof. The dry-spandex is prepared by a dissolving and blending method, so that the composite spandex has high setting property and good mechanical strength.

[0005] Technical solution: The application provides a low-temperature easy-setting composite spandex, which contains polyvinyl acetal and polyurethane-urea two components; the mass ratio of the polyvinyl acetal to the polyurethane-urea is 10:90-50:50.

[0006] The preparation method comprises the following steps:

[0007] 1) mixing polyvinyl acetal with a solvent to obtain a polyvinyl acetal solution;

[0008] 2) reacting polymer polyol, diisocyanate, diamin chain extender and terminator to obtain a polyurethane-urea solution;

[0009] 3) mixing the two solutions to obtain a spinning dope, and preparing the low-temperature easy-setting composite spandex through dry spinning.

[0010] Among them:

[0011] The mass concentration of the polyvinyl acetal solution is 20-30wt%.

[0012] The polymer polyol is polyether diol or polyester diol with a number average molecular weight of 1000-5000g / mol, including one or more of polytetrahydrofuran diol, polyethylene glycol or polypropylene glycol.

[0013] The diisocyanate includes one or more of toluene diisocyanate, diphenyl methane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dimethyl diphenyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dicyclohexyl methane diisocyanate and / or derivatives and / or modified polymers.

[0014] The diamin chain extender includes C2-C8 small molecule diamine, including one or more of ethylenediamine, propylenediamine, pentanediamine and hexanediamine.

[0015] The terminator includes C2-C10 small molecule monoamine or monoalcohol, including one or more of dimethylamine, diethylamine, dipropylamine, n-butanol and ethanolamine.

[0016] The dry spinning nozzle temperature is set to 200-220 DEG C, and the spinning winding speed is 500-600 m / min.

[0017] Beneficial effects: adding a proper amount of polyvinyl acetal in spandex can effectively reduce the internal phase separation degree of spandex, weaken the intermolecular force, make the molecular chain quickly dissociate and rearrange under lower energy conditions, and realize efficient setting of spandex. In addition, the microcrystalline structure formed by polyvinyl acetal can act as a physical crosslinking point inside the fiber, maximizing the retention of the original mechanical strength and elasticity of spandex fibers. The low-temperature easy-setting spandex bare yarn of the present application has a setting efficiency of 70% at 120-140°C, and the fabric mixed with polylactic acid fiber and polyethylene fiber has good setting effect and a shrinkage rate of less than 3.0%. DETAILED DESCRIPTION

[0018] The low-temperature easy-setting composite spandex contains polyvinyl acetal and polyurethane-urea, and is obtained by dry spinning with the polyurethane-urea and polyvinyl acetal as the spinning raw material.

[0019] The mass ratio of the polyvinyl acetal and the polyurethane-urea is 10:90-50:50;

[0020] The polyvinyl acetal includes the reaction product of polyvinyl alcohol and aldehyde substances, and the aldehyde substances include formaldehyde and / or butyraldehyde; further, the aldehyde substances include formaldehyde; further, the polyvinyl acetal includes at least one of polyvinyl formal and polyvinyl butyral, and preferably polyvinyl formal; and the product brand can be one or a combination of PA98897 of Guangdong Wengjiang Chemical Reagent Co., Ltd., BD6468 of Hubei Baodu Chemical Co., Ltd., XHL6931 of Hubei Xinhongli Chemical Co., Ltd., and XK1325 of Hubei Xinkang Pharmaceutical Chemical Co., Ltd.

[0021] The number average molecular weight of the polyvinyl acetal is 40,000-80,000 g / mol;

[0022] In the present application, by adding a proper amount of polyvinyl acetal polymer with low softening point, easy solubility in polar solvents, and thermoplasticity in spandex, composite spandex can be obtained by directly mixing the two substances for dry spinning, and the heat-deformable property of polyvinyl acetal is utilized to make spandex have heat setting property at a lower temperature. Compared with adding other low-melting-point polymers such as TPU in spandex, polyvinyl acetal has the characteristics of low thermoplastic temperature and self-crystallization, which can not only reduce the temperature required for setting, but also form a microcrystalline structure as a physical crosslinking point inside the composite fiber.

[0023] The polyurethane-urea includes the reaction product of polymeric polyol, diisocyanate, diamine chain extender, and terminator;

[0024] Further, the polyurethane-urea is prepared by reacting the polymer polyol and diisocyanate to obtain a prepolymer, and then reacting the prepolymer with a diamine chain extender and a terminating agent;

[0025] The polymer polyol is a polyester polyol and / or a polyether polyol, and the polyether polyol includes one or more of polytetrahydrofuran diol, polyethylene glycol, or polypropylene glycol.

[0026] The number average molecular weight of the polymer polyol is 1000-5000 g / mol.

[0027] The diisocyanate includes one or more of toluene diisocyanate, diphenyl methane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dimethyl diphenyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dicyclohexyl methane diisocyanate, and / or derivatives and / or modified polymers.

[0028] The diamine chain extender includes a small molecule diamine with a carbon number of 2-8, and the small molecule diamine includes one or more of ethylenediamine, propylenediamine, pentanediamine, and hexanediamine.

[0029] The terminating agent includes a small molecule monoamine or monoalcohol with a carbon number of 2-10, and further includes one or more of dimethylamine, diethylamine, dipropylamine, n-butanol, and ethanolamine.

[0030] In some examples of the present application, the polyurethane-urea preparation method includes the following steps:

[0031] The polymer polyol and diisocyanate are reacted to obtain a prepolymer-containing product, the prepolymer is dissolved in a solvent to obtain a prepolymer solution, and the prepolymer solution is reacted with a mixed amine solution containing a diamine chain extender and a terminating agent to obtain a polyurethane-urea stock solution;

[0032] The mass proportion of the polymer polyol in the polyurethane-urea is 65-85 wt%.

[0033] The mass proportion of the diisocyanate in the polyurethane-urea is 15-25 wt%.

[0034] The mass proportion of the diamine chain extender in the polyurethane-urea is 2-8 wt%.

[0035] The mass proportion of the monoamine end-capping agent in the polyurethane-urea is 0.1-1.0 wt%.

[0036] The solvent includes one or more of N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide.

[0037] In some examples of the present application, the method for preparing the low-temperature easy-setting composite spandex comprises the following steps:

[0038] (1) mixing polyvinyl acetal with a solvent to obtain a polyvinyl acetal solution;

[0039] (2) obtaining a polyurethane-urea stock solution by using a two-step pre-polymerization-chain extension method;

[0040] (3) mixing the two obtained solutions to obtain a spinning stock solution, and spinning the spinning stock solution through a spinning pack to obtain the low-temperature easy-setting spandex;

[0041] Preferably, the polyvinyl acetal is subjected to drying treatment before the dissolving process in step (1), and the drying temperature is 50-60°C, and the drying time is 10-24 hours;

[0042] Preferably, the mixing temperature of the polyvinyl acetal and the solvent in step (1) is 70-80°C, and the mixing time is 3-6 hours; and the polyvinyl acetal solution can be optionally subjected to filtration treatment to remove impurities and small solid particles that are not fully dissolved;

[0043] Preferably, the mass concentration of the polyvinyl acetal solution in step (1) is 20-30wt%, and the viscosity is 2000-3000P;

[0044] Preferably, the mass concentration of the polyurethane-urea stock solution in step (2) is 30-40wt%, and the viscosity is 2000-3000P;

[0045] Preferably, the mixing temperature in step (3) is 40-60°C, and the mixing time is 100-120 minutes;

[0046] Preferably, the mass concentration of the spinning stock solution in step (3) is 25-35wt%, and the viscosity is 2000-3000P;

[0047] In the formula, the mass concentration of the solution = mass of solute / mass of total solution x 100%;

[0048] Preferably, the spinning stock solution can be subjected to aging before spinning in step (3), and the aging temperature is 25-45°C, and the aging time is 15-30 hours.

[0049] Preferably, the spinning method in step (3) is dry spinning technology.

[0050] Preferably, the spinning through the spinning pack in step (3) further comprises the steps of spinning duct drying, false twisting, oiling, drawing, and winding forming;

[0051] Preferably, the temperature of the spinning duct is 200-220°C, and the winding speed is 500-600 m / min.

[0052] The following examples are used to describe the production process of the present application in detail, but these examples should not be understood as any limitation of the present application.

[0053] Preparation of polyvinyl formal solution:

[0054] Commercially available polyvinyl formal is dried at 50°C for 12 hours to remove water; then it is mixed with N,N-dimethylacetamide and stirred at 70°C for 4 hours; the polyvinyl formal solution is filtered to remove impurities and small particles of incompletely dissolved solids, obtaining a polyvinyl formal solution with a mass concentration of 25wt%.

[0055] Preparation of polyurethane-urea solution:

[0056] Polytetrahydrofuran diol (number average molecular weight 1800) is mixed with diphenyl methane diisocyanate and reacted at 70°C for 2 hours to obtain a prepolymer; an ethylenediamine-n-butanol mixture is added dropwise to the prepolymer for chain extension reaction, and N,N-dimethylacetamide is added for dilution, obtaining a polyurethane-urea stock solution with a mass concentration of 35wt%. The mass ratio of polytetrahydrofuran diol:diphenyl methane diisocyanate:ethylenediamine:ethylenediamine is 75:20:4.5:0.5; the polyurethane-urea solution used in the examples and comparative examples of the present application is of this type.

[0057] The specific types and proportions of raw materials used in the examples and comparative examples are shown in Table 1 below:

[0058]

[0059]

[0060] Preparation of composite spandex:

[0061] The polyvinyl formal solution and the polyurethane-urea solution are added to a static mixer and mixed at 40°C for 120 minutes; after thorough mixing, the composite spinning stock solution is aged at 45°C for 20 hours, and the mass concentration of the composite spinning stock solution is controlled to be 35%;

[0062] The composite spinning stock solution is extruded through a spinning pack, N,N-dimethylacetamide is removed through a 220°C spinning duct, false twisting is performed, a spinning oil agent is applied, and the composite spandex is wound at a speed of 600 m / min to obtain 20 denier composite spandex.

[0063] The spinning conditions and spinnability of the examples and comparative examples are shown in Table 2 below:

[0064] Spinnability: record the total number of spinning failures within 48 hours, spinning failures include broken yarn, doubling, and other spinning process stops caused by dope problems. Spinnability is excellent if the total number of failures is less than 1, good if the total number of failures is 2-4, and poor if the total number of failures is more than 5;

[0065] Table 2:

[0066]

[0067] The fibers prepared in the examples and comparative examples were tested for spinnability, mechanical properties, bare yarn setting efficiency, and fabric shrinkage, and the test methods were as follows:

[0068] (1) Mechanical properties: detection according to the textile industry standard "Spandex Yarn Tensile Property Test Method" (FZ / T5006-2013);

[0069] (2) Setting efficiency: measure 10 cm of sample, stretch 2 times, and then place in a dry heat oven at 120-140 degrees for 2 minutes; after cooling for 30 minutes, measure the length of the sample again. The calculation formula for setting efficiency is as follows:

[0070] Setting efficiency = (L2-L0) / (L1-L0)*100%.

[0071] Wherein: L0 is the original length, L1 is the length after stretching, and L2 is the length after setting.

[0072] (3) Fabric shrinkage: cut a piece of fabric greater than 1 square meter of composite spandex and polylactic acid fiber interwoven, and reserve the selvedge; use a needle clip to fix the fabric sample, and then place in a 120-140 degree oven for setting for 2 minutes, and cool for 30 minutes. Mark a 100*100 cm square at a certain distance from the selvedge inward; wash the fabric sample in 30 degree warm water, and then dry with a dryer. After fully cooling, measure the size of the marked square in the warp and weft directions. The calculation formula for shrinkage is as follows:

[0073] Shrinkage = (M0-M1) / M0*100%

[0074] Wherein: M0 is the size before washing, and M1 is the size after washing.

[0075] The performance test results of the fibers prepared in the examples and comparative examples are shown in Table 3 below:

[0076] Table 3:

[0077]

Claims

1. A low temperature settable composite spandex characterized in that, The low-temperature easy-setting composite spandex contains polyvinyl acetal and polyurethane-urea; the mass ratio of the polyvinyl acetal to the polyurethane-urea is 10:90-50:50; the number average molecular weight of the polyvinyl acetal is 40,000-80,000 g / mol; and the polyurethane-urea and the polyvinyl acetal are used as spinning raw materials to obtain the low-temperature easy-setting composite spandex through dry spinning.

2. A process for the production of a low temperature set composite spandex fiber as claimed in claim 1, characterized in that, The preparation method comprises the following steps: 1) mixing polyvinyl acetal with a solvent to obtain a polyvinyl acetal solution; 2) obtaining a polyurethane-urea solution through the reaction of a polymer polyol, a diisocyanate, a diamine chain extender, and a terminator; 3) mixing the polyvinyl acetal solution and the polyurethane-urea solution to obtain a spinning solution, and preparing the low-temperature easy-setting composite spandex through dry spinning.

3. The method for preparing low-temperature easily shaped composite spandex according to claim 2, characterized in that, The polyvinyl acetal is at least one of polyvinyl formal and polyvinyl butylal.

4. The method for preparing low-temperature easily shaped composite spandex according to claim 2, characterized in that, The mass concentration of the polyvinyl acetal solution is 20-30 wt%.

5. The method for preparing low-temperature easily shaped composite spandex according to claim 2, characterized in that, The polymer polyol is polyether diol or polyester diol with a number average molecular weight of 1,000-5,000 g / mol.

6. The method for preparing low-temperature easily shaped composite spandex according to claim 5, characterized in that, The polyether diol comprises one or more of polytetrahydrofuran diol, polyethylene glycol, and polypropylene glycol.

7. The method for preparing low-temperature easily shaped composite spandex according to claim 2, characterized in that, The diisocyanate comprises one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dimethyl diphenyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, and dicyclohexylmethane diisocyanate.

8. The process for the preparation of low temperature set composite spandex of claim 2, wherein, The diamine chain extender comprises a small molecule diamine with 2-8 carbon atoms.

9. The method for preparing low-temperature easily shaped composite spandex according to claim 8, characterized in that, The small molecule diamine comprises one or more of ethylenediamine, propylenediamine, pentanediamine, and hexanediamine.

10. The process for the preparation of low temperature set composite spandex of claim 2, wherein, The terminator comprises a small molecule monoamine or monoalcohol with 2-10 carbon atoms.

11. The method for preparing low-temperature easily shaped composite spandex according to claim 10, characterized in that, The small molecule monoamine comprises one or more of dimethylamine, diethylamine, dipropylamine, and ethanolamine, and the monoalcohol comprises n-butanol.

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