Polytrimethylene terephthalate hollow composite staple fibers and process for producing same

Abstract

The polytrimethylene terephthalate hollow composite staple fibers exhibiting a latent crimping property and high bulkiness and elastic recovery and useful for nonwoen, woven and knitted fabrics and cushioning materials, have a hollow side-by-side or core-in-sheath type structure formed from two polytrimethylene terephthalate resin components one of which has an intrinsic viscosity of 0.50 to 1.40 dl / g and other one of which has an intrinsic viscosity of 0.40 to 1.30 dl / g and 0.1 to 0.5 dl / g below that of the former, and having a hollow part with a cross-sectional area of 2 to 15% of the total cross-sectional area, and exhibit, after the hollow composite staple fibers are formed into a web having a basis weight of 30 g / m2, and the web is heated at 120° C. for 10 minutes to cause the web to freely shrink, an area thermal shrinkage of 30 to 70% based on the original area of non-heated web.

Description

FIELD OF THE INVENTION [0001] The present invention relates to polytrimethylene terephthalate hollow composite staple fibers and a process for producing the same. Particularly, the present invention relates to polytrimethylene terephthalate hollow composite staple fibers having a latent crimping property, and a process for producing the same with a high efficiency. The polytrimethylene terephthalate hollow composite staple fibers of the present invention are useful for nonwoven fabrics, woven and knitted fabrics and cushioning materials having a high bulkiness and an excellent elastic recovery. BACKGROUND ART [0002] Polytrimethylene terephthalate fibers have excellent dimensional stability, light resistance, and heat-setting properties and low water- and moisture-absorption properties which are normal for polyester fibers and, further, they exhibit a low elastic modulus and an excellent elastic recovery and easy dyeability. Therefore, the polytrimethylene terephthalate fibers are ex...

AI Technical Summary

Benefits of technology

[0006] An object of the present invention is to provide polytrimethylene terephthalate hollow composite staple fibers which have excellent bulkiness and elastic recovery and one appropriate for forming therefrom nonwoven fabrics, bulky yarns, bulky woven and knitted fabrics and cushioning materials, and a process for producing the same.

Problems solved by technology

It has been found, however, that when the difference in the intrinsic viscosity between the two types of polyester components in the composite fiber is increased to enhance the latent crimping property of the resultant composite fiber, the composite filamentary polymer melt streams extruded in the melt-spinning procedure bend, the degree of bending of the composite filamentary streams significantly increases with increase in the difference in the intrinsic viscosity between the two polyester components and, as a result, the bent composite streams adhere to adjacent streams or to the spinneret and are broken.

Therefore, the melt-spinning procedure cannot be stably carried out.

Further, as the polytrimethylene terephthalate composite filaments exhibit a lower rigidity than that of conventional polyethylene terephthalate composite filaments, when the latent crimps of the composite fibers are realized, a plurality of small crimps are created on the composite filaments and thus the resultant crimped composite filaments difficult to exhibit a satisfactory bulkiness.

The composite fibers have, however, an insufficient bulkiness and thus are not suitable for bulky nonwoven fabrics and cushioning materials.

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