A process for producing a thermoplastic polyurethane fiber with low shrinkage, and the use of the fiber

Abstract

A process produces a thermoplastic polyurethane (TPU) fiber with low shrinkage, in particular at a high spinning speed. The resulting fiber can be used for fabric, especially for garments and shoes. The process combines the high-speed spinning process with the heat-setting process. This allows the process to produce a TPU fiber in high productivity, which could greatly decrease the cost. Moreover, the obtained TPU fiber has very low shrinkage of <10%, which makes it well suitable as the main raw material in fabrics.

1 : A process for producing a TPU fiber, comprising:
 (a) melt-spinning a composition comprising a TPU resin into a fiber; and   (b) heat setting the fiber.   
     
     
         2 : The process according to  claim 1 , wherein the melt-spinning is carried out at a spinning rate of 2000-6500 m/min. 
     
     
         3 : The process according to  claim 1 , wherein (a) comprises passing a spun fiber through 2 or more, but no more than 6 godet rollers. 
     
     
         4 : The process according to  claim 3 , wherein the godet rollers are heated. 
     
     
         5 : The process according to  claim 3 , wherein there are 3 godet rollers, GR1, GR2, and GR3. 
     
     
         6 : The process according to  claim 5 , wherein a temperature of GR1 is 30-150° C., a temperature of GR2 is 60-200° C., and a temperature of GR3 is 30-150° C. 
     
     
         7 : The process according to  claim 5 , wherein a speed of GR1 is 1000-6000 m/min, a speed of GR2 is 2000-6000 m/min, and a speed of GR3 is 2000-6000 m/min. 
     
     
         8 : The process according to  claim 1 , wherein the heat setting is carried out by keeping a spun TPU fiber in a heating oven. 
     
     
         9 : The process according to  claim 8 , wherein a heat setting temperature is 70-130° C. and a heat setting time is 30-240 minutes. 
     
     
         10 : The process according to  claim 1 , wherein the heat setting is carried out by making a spun fiber pass through a set of hot godet rollers without further drawing or orienting. 
     
     
         11 : The process according to  claim 10 , wherein a number of the hot godet rollers is 2 or more, but not more than 6. 
     
     
         12 : The process according to  claim 10 , wherein there are 3 hot godet rollers, GR4, GR5, and GR6. 
     
     
         13 : The process according to  claim 12 , wherein a temperature of GR4 is 70-150° C., a temperature of GR5 is 100-180° C., and a temperature of GR6 is 80-140° C. 
     
     
         14 : The process according to  claim 12 , wherein a speed of GR4 is 300-900 m/min, a speed of GR5 is 300-800 m/min, and a speed of GR6 is s 200-800 m/min. 
     
     
         15 : The process according to  claim 1 , wherein a hardness of the TPU is from Shore 80 A to Shore 80 D, as measured according to DIN ISO 7619-1. 
     
     
         16 : The process according to  claim 1 , wherein the TPU is a reaction product of;
 (a) isocyanate,   (b) polyol, and   (c) chain extender; and   optionally, in the presence of   (d) catalyst and/or   (e) auxiliary agent.   
     
     
         17 : The process according to  claim 16 , wherein the isocyanate is at least one selected from the group consisting of 2,2′-, 2,4′, and 4,4′-diphenylmethane diisocyanate (MDI); 1,5-naphthylene diisocyanate (NDI); 2,4- and 2,6-tolylene diisocyanate (TDI); diphenylmethane diisocyanate; 3,3′-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and phenylene diisocyanate; tri, tetra, penta, hexa, hepta, and octamethylene diisocyanate; 2-methylpentamethylene-1,5-diisocyanate; 2-ethylbutylene-1,4-diisocyanate; 1,5-pentamethylene diisocyanate; 1,4-butylene diisocyanate; 1-diisocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane (IPDI); 1,4- and 1,3-bis(isocyanatomethyl)cyclohexane (HXDI); 1,4-cyclohexane diisocyanate; 1-methyl-2,4- and -2,6-cyclohexane diisocyanate; and 4,4′-, 2,4′-, and 2,2′-dicyclohexylmethane diisocyanate. 
     
     
         18 : The process according to  claim 16 , wherein the polyol is selected from the group consisting of polyester polyol, polyether polyol, polycaprolactone polyol, and polycarbonate polyol. 
     
     
         19 : The process according to  claim 16 , wherein the chain extender is selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,10-decanediol, 1,2-dihydroxycyclohexane, 1,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, bis(2-hydroxyethyl) hydroquinone; triols, and a combination thereof. 
     
     
         20 : A TPU fiber obtained by the process according to  claim 1 . 
     
     
         21 : A fabric comprising the TPU fiber according to  claim 20 . 
     
     
         22 : A product comprising the fabric according to  claim 21 ,
 wherein the product is a shoe, pants, T-shirt, chair mesh, watch band, or hair band.