A method for preparing antistatic spandex and the prepared antistatic spandex

Abstract

The present invention provides a method for preparing an antistatic spandex and the obtained antistatic spandex, the preparation method is as follows: (1) N-alkyldiethanolamine containing a tertiary nitrogen group is added to PTMG, and then mixed with a diisocyanate compound to obtain an isocyanate-terminated prepolymer. (2) After the prepolymerization reaction is completed, DMAc with an acid value of 200ppm-3000ppm is used for dissolution; (3) a chain extender and a terminator are added to the prepolymer solution for chain extension reaction, and a spandex spinning solution is obtained after adding additives; (4) dry spinning is performed to obtain antistatic spandex. The present invention introduces N-alkyldiethanolamine containing a tertiary nitrogen group into the diol raw material of spandex, and DMAc with a specific acid value is used to dissolve the prepolymer after the prepolymerization reaction. The acetic acid in the DMAc reacts with the tertiary nitrogen group to form an ammonium acetate salt of tertiary nitrogen fixed on the main chain of the spandex molecule, so that the spandex has conductivity, and the charge on the surface of the spandex fiber can be derived, thereby playing an antistatic role.

Description

Technical Field

[0001] The invention relates to the field of spandex manufacturing, and in particular to a method for preparing antistatic spandex. Background Art

[0002] Spandex fiber usually refers to a block copolymer containing repeated carbamate segments on the main chain. Spandex fiber can be blended with cellulose fiber, polyester fiber, polyamide fiber and acrylic fiber to be used in underwear, socks, swimwear, sportswear and other clothing fabrics, and provide excellent elasticity and recovery of the fabric.

[0003] During the weaving process, spandex yarn will rub against metal and carry static charge. If the static charge cannot be conducted away from the spandex yarn in time, it will cause the spandex yarn to have stripe problems during the unwinding and weaving process, that is, the fiber is subjected to additional force, resulting in the local fiber distribution on the cloth surface being inconsistent with other places, resulting in stripes. The existing spandex antistatic is mainly achieved by using special antistatic oils in the oiling process of the spandex production process to improve the antistatic properties of the spandex yarn.

[0004] In addition, during the production of spandex multifilaments, if the fiber surface of the spandex filaments in the channel carries an electric charge, repulsive force will be generated between the spandex filaments, which is not conducive to the bonding of the porous spandex multifilaments. The spandex multifilaments composed of multiple filaments cannot form a synergistic effect due to their single filaments, thereby reducing the overall mechanical properties of the bonded multifilaments. Summary of the invention

[0005] The present invention provides a method for preparing an antistatic spandex and the prepared antistatic spandex, and the specific scheme is as follows:

[0006] A method for preparing antistatic spandex, characterized in that it comprises the following steps:

[0007] (1) N-alkyldiethanolamine containing a tertiary nitrogen group is added to PTMG, and then mixed with a diisocyanate compound to obtain an isocyanate-terminated prepolymer.

[0008] (2) After the prepolymerization reaction is completed, DMAc with an acid value of 200ppm-3000ppm is used for dissolution;

[0009] (3) adding a chain extender and a terminator to the prepolymer solution to carry out a chain extension reaction, and obtaining a spandex spinning solution after adding the additives;

[0010] (4) Dry spinning is performed to obtain antistatic spandex.

[0011] Optionally, the N-alkyldiethanolamine containing a tertiary nitrogen group is one or more of N-methyldiethanolamine and N-tert-butyldiethanolamine.

[0012] Optionally, the amount of the N-alkyldiethanolamine containing a tertiary nitrogen group added is no more than 5% of the mass of the PTMG.

[0013] Beneficial effects:

[0014] The present invention introduces N-alkyldiethanolamine containing tertiary nitrogen groups into the diol raw materials of spandex, uses DMAc with a specific acid value to dissolve the prepolymer after prepolymerization, and the acetic acid in DMAc reacts with the tertiary nitrogen groups to form ammonium acetate salt of tertiary nitrogen fixed on the main chain of the spandex molecule, so that the spandex has conductivity, and the charge on the surface of the spandex fiber can be guided out, thereby playing an antistatic role. The method provided by the present invention is simple in process and can produce antistatic spandex without additional equipment.

[0015] The spandex yarn spun by the method of the present invention has lower surface resistance, can lead out the net surface charge, improve the cohesion of the spandex yarn in the tunnel spinning process, reduce the net charge generated by the friction of the spandex yarn in the weaving process, and reduce the problem of the spandex-containing fabric being even. DETAILED DESCRIPTION

[0016] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention is further clearly and completely described below through embodiments. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification.

[0017] The present invention aims to produce an antistatic spandex. By introducing tertiary nitrogen groups into diol raw materials and controlling the acid value of the solvent, the acetate ammonium salt of tertiary nitrogen is obtained on the main chain of the spandex, which reduces the surface resistance of the spandex yarn and can lead out the charge, thereby improving the antistatic property of the spandex yarn.

[0018] Specifically, the method provided by the present invention is as follows:

[0019] A method for preparing antistatic spandex, characterized in that it comprises the following steps:

[0020] (1) N-alkyldiethanolamine containing a tertiary nitrogen group is added to PTMG, and then mixed with a diisocyanate compound to obtain an isocyanate-terminated prepolymer.

[0021] The two hydroxyl groups in the N-alkyldiethanolamine containing tertiary nitrogen groups can react with diisocyanate to introduce tertiary nitrogen groups into the main chain of the spandex molecule.

[0022] Optionally, the N-alkyldiethanolamine containing a tertiary nitrogen group is one or more of N-methyldiethanolamine and N-tert-butyldiethanolamine, which have smaller molecular weights and can provide more tertiary nitrogen. The amount of the N-alkyldiethanolamine containing a tertiary nitrogen group added is no more than 5% of the mass of the PTMG.

[0023] (2) After the prepolymerization reaction is completed, DMAc with an acid value of 200ppm-3000ppm is used for dissolution;

[0024] DMAc is called N,N-dimethylacetamide, and its chemical formula is CH3C(O)N(CH3)2. DMAc is usually used as a solvent in the spandex dry spinning production process. The acid value of DMAc mainly comes from the acetic acid generated by the partial decomposition of DMAc during the high-temperature spinning process. In the scheme of the present invention, the acid value of DMAc is controlled to be 200ppm-3000ppm, that is, the acetic acid in DMAc is controlled to be maintained at a certain content, so that in the process of dissolving the prepolymer in the solvent to obtain the prepolymer solution in step (1), the tertiary nitrogen group in the prepolymer can react with acetic acid to obtain the tertiary nitrogen ammonium acetate salt. In the process of spandex dry spinning, DMAc needs to be recycled as a solvent. The acid value of the recycled DMAc is usually around 3000ppm, while the acid value of DMAc used as a solvent in the conventional spandex production process is generally required to be lower than 150ppm. Compared with the conventional spandex production process, the scheme of the present invention also reduces the requirement for the acid value of DMAc. In the present invention, the acid value of DMAc is determined according to the amount of N-alkyldiethanolamine. The acid value of DMAc is mainly used to neutralize tertiary nitrogen groups. If the acid value is too low, it will not reduce the surface resistance of spandex, while if the acid value is too high, the amine in the amine solution will be consumed during the subsequent chain extension. Therefore, in the present invention, the acid value of DMAc is controlled to be 200ppm-3000ppm, preferably 200ppm-2000ppm.

[0025] (3) adding a chain extender and a terminator to the prepolymer solution to carry out a chain extension reaction, and obtaining a spandex spinning solution after adding the additives;

[0026] In the spinning stock solution after chain extension, the polyurethane molecular chain already carries the ammonium acetate salt of tertiary nitrogen, so the spandex yarn obtained after the next spinning step also carries the ammonium acetate salt of tertiary nitrogen.

[0027] (4) Dry spinning is performed to obtain antistatic spandex.

[0028] In the spandex yarn obtained by dry spinning, the spandex has tertiary nitrogen ammonium acetate salt on the molecular chain. Since the tertiary nitrogen ammonium acetate salt is an ionic compound with conductivity, the charge generated by static electricity can be conducted away in time, avoiding static electricity accumulation and electrostatic interaction. In addition, the salt is water-absorbent and will also absorb moisture in the air of the weaving workshop during actual use. With the help of water, the conductivity of ions will also be enhanced, making it easier to conduct away the accumulated charge. The gist of the present invention will be further explained in conjunction with the following series of embodiments.

[0029] Example 1

[0030] (1) adding N-methyldiethanolamine to polytetramethylene ether glycol (PTMG), a raw material, to obtain a diol mixture, wherein the amount of N-methyldiethanolamine added is 2%, and then mixing the diol mixture with MDI, reacting at 90° C. for 120 minutes, to prepare an isocyanate-terminated prepolymer;

[0031] (2) After the prepolymerization reaction is completed, the prepolymer is cooled and dissolved in DMAc having an acid value of 2000 ppm to prepare a solution having a mass percent concentration of 44.2%;

[0032] (3) dissolving ethylenediamine and diethylamine in a solvent N,N-dimethylacetamide to form a mixed amine solution with a mass percentage concentration of 7.00%, adding the prepared mixed amine solution to the N,N-dimethylacetamide solution of the prepolymer and rapidly stirring to carry out a chain extension reaction, and after the chain extension reaction is completed, adding necessary antioxidants, dyeing aids and other additives, and aging for 30 hours to form a polyurethane solution with a mass percentage concentration of 35%;

[0033] (4) Dry spinning is performed to obtain antistatic spandex.

[0034] Comparative Example 1

[0035] (1) In the raw material polytetramethylene ether glycol PTMG, the diol mixture and MDI are mixed, and the mixture is reacted at 90° C. for 120 minutes to prepare an isocyanate-terminated prepolymer;

[0036] (2) After the prepolymerization reaction is completed, the prepolymer is cooled and dissolved in DMAc having an acid value of 2000 ppm to prepare a solution having a mass percent concentration of 44.2%;

[0037] (3) dissolving ethylenediamine and diethylamine in a solvent N,N-dimethylacetamide to form a mixed amine solution with a mass percentage concentration of 7.00%, adding the prepared mixed amine solution to the N,N-dimethylacetamide solution of the prepolymer and rapidly stirring to carry out a chain extension reaction, and after the chain extension reaction is completed, adding necessary antioxidants, dyeing aids and other additives, and aging for 30 hours to form a polyurethane solution with a mass percentage concentration of 35%;

[0038] (4) Dry spinning is performed to obtain spandex.

[0039] The antistatic test uses a volume surface resistance tester to test the resistance. It is generally believed that when the resistance value is less than 10 7 Ohms, static electricity can be conducted away in time, thus avoiding static electricity accumulation. After testing, the resistance value of antistatic spandex is 6.2*10 6 Ohm, while the resistance of ordinary spandex is 8.5*10 9Ohm, indicating that the spandex yarn prepared by this scheme can significantly reduce the resistance value of the spandex yarn, and can conduct static electricity away in time, thereby avoiding static electricity accumulation.

Claims

1. A method for preparing antistatic spandex, characterized in that: The steps include: (1) N-alkyldiethanolamine containing a tertiary nitrogen group is added to PTMG, and then mixed with a diisocyanate compound to obtain an isocyanate-terminated prepolymer. (2) After the prepolymerization reaction is completed, DMAc with an acid value of 200ppm-3000ppm is used for dissolution; (3) adding a chain extender and a terminator to the prepolymer solution to carry out a chain extension reaction, and obtaining a spandex spinning solution after adding the additives; (4) Dry spinning is performed to obtain antistatic spandex.

2. The preparation method according to claim 1, characterized in that: The N-alkyldiethanolamine containing a tertiary nitrogen group is one or more of N-methyldiethanolamine and N-tert-butyldiethanolamine.

3. The preparation method according to claim 1, characterized in that: The amount of the N-alkyldiethanolamine containing a tertiary nitrogen group added is no more than 5% of the mass of the PTMG.

4. The antistatic spandex prepared according to the method for preparing the antistatic spandex according to any one of claims 1 to 3.