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.

Claims

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.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0089] FIG. 1 shows an example of the apparatus for melt spinning, wherein the reference number 1 represents a spin pack, and 2 represents a winder, and GR1, GR2 and GR3 are godet rollers.

[0090] FIG. 2 shows an example for the apparatus for Mode B, wherein the reference number 3 represents a set of heated rollers GR4, GR5 and GR6, and 4 represents a winder.

EXAMPLES

[0091] Measuring and Test Methods

[0092] The measuring and test methods are shown in Table 1.

TABLE-US-00001 TABLE 1 Property Unit Testing standard Denier per filament (DPF) De GB/T 14343-2008 Tenacity cN/dtex GBT 14344-2008 Elongation at break % GB/T 14343-2008 Shrinkage in boiling water of the fiber % GB/T 6505-2008, skein method

[0093] Moreover, the shrinkage of the fabric is measured as follows: taking out of a piece of fabric with a size of 50 cm×50 cm as a sample; drawing two marks on the sample with a crayon; measuring the distance between the two marks and denoted as L.sub.0; ironing the sample for 15 seconds by using a commercial steam iron under the conditions for ironing synthetic fibers; then cooling to the room temperature, measuring the distance between the two marks and denoted as L.sub.1; calculating the shrinkage of the fabric according to the formula of shrinkage=(L.sub.0−L.sub.1)/L.sub.0×100%.

[0094] Materials

[0095] The materials used in the examples are as follows.

[0096] One polyether based Elastollan® product SP9519 with a weight-average molecular weight of 80 000-200 000 based on PTMEG, MDI and 1,4-butanediol (obtained from BASF, having a Shore D hardness of 60-64) was used for preparing the fiber.

[0097] Finish oil: a finish oil (obtained from Takemoto Oil & Fat Co., Ltd) was used during the spinning process.

[0098] The general description of the process used in the examples

[0099] By using the apparatus shown in FIG. 1, the TPU is spun out of the spin pack at a temperature of 230° C., and the spun fibers are passed through the godet rollers GR1, GR2 and GR3 with the temperatures and speeds as indicated in Table 2. Then, the resulted fibers are subjected to heat setting in Mode A and B, respectively, and the conditions and the results are shown in Table 3 and 4, respectively. The fiber is oiled after spinning out from the spin pack and before reaching godet roller GR1; moreover, after the heat setting, the fiber is oiled again for easy processing in the following twisting process.

TABLE-US-00002 TABLE 2 Experiment No. Example 1 1-1 1-2 1-3 Condition of TPU Fiber Making Shrinkage GR1 ° C. 60 80 80 control during temperature spinning GR2 ° C. 100 140 140 temperature GR3 ° C. 60 80 80 temperature GR1 speed m/min 2500 2800 3300 GR2 speed m/min 2600 3000 3500 GR3 speed m/min 2800 3300 3800 Winder speed m/min 3000 3500 4000 Property of the Fiber DPF De 15 10 6 Tenacity cN/dtex 2.4 2.7 3.1 Elongation at break % 60 50 45 Shrinkage % 25 28 33 Property of the Fabric Shrinkage % 27 30 35

TABLE-US-00003 TABLE 3 Experiment No. Example 2 2-1 2-2 The fiber Sample No. 1-1 produced in Example 1 was treated by Mode A. Condition of TPU Fiber Heat Setting Mode A Oven ° C. 80 110 temperature Oven heating min 120 60 time Property of the Fiber DPF De 17 17.5 Tenacity cN/dtex 2.3 2.3 Elongation at break % 66 68 Shrinkage % 3 2.6 Property of the Fabric Shrinkage % 4.5 4

TABLE-US-00004 TABLE 4 Experiment No. Example 3 3-1 3-2 The fiber Sample No. 1-1 produced in Example 1 was treated by Mode B. Condition of TPU Fiber Heat Setting Mode B GR4 speed m/min 500 650 GR5 speed m/min 470 630 GR6 speed m/min 450 600 Winder speed m/min 400 550 GR4 temperature ° C. 120 120 GR5 temperature ° C. 140 140 GR6 temperature ° C. 120 120 Property of the Fiber DPF De 16.6 16.4 Tenacity cN/dtex 2.3 2.3 Elongation at break % 65 64 Shrinkage % 4.7 5.2 Property of the Fabric Shrinkage % 6 7

[0100] In Example 1, the fibers are only subjected to the shrinkage controlling treatment during spinning without heat setting treatment after the spinning; while in Example 2, the fibers are subjected to bath of the shrinkage controlling treatment during spinning and the heat setting treatment in Mode A, and in Example 3, the fibers are subjected to subjected to bath of the shrinkage controlling treatment during spinning and the heat setting treatment in Mode B.

[0101] As is evident from the above, the shrinkages of the fibers resulted from Example 2 and 3 are much less than those of Example 1, at the same time, the elongation at break of the fibers resulted from Example 2 and 3 are higher than those of Example 1.