Toray Industries, Inc.

Yoshiaki Sato

Hajime Arai

Kiyoshi Nakagawa

Hisao Suzuki

The present invention relates to an advanced silky thermoplastic polymer fiber being thick and thin along its axis and having two or more, preferably more than two axially-continuous grooves per filament with the entrance widths of 0.2 to 4.mu. and the depths of 0.1 to 1.8.mu.. The said fiber can be formed by dissolving out at least part of a easily-soluble polymer from a drawn composite fiber comprised of two differently-soluble thermoplastic polymer components, the easily-soluble one of said components having at least two locations with the areas of 0.2 to 4.mu. at the periphery of the transverse cross-section thereof and being thick and thin along its axis.

Thick and thin fiber having grooves on its surface and process for

A separable unitary composite fiber of the type having a substantially uniformly shaped transverse cross-section along its length and comprised of at least two different polymer components, one of which is soluble in a given solvent and the other of which is relatively insoluble in the given solvent; a plurality of segments of the relatively insoluble polymer component being isolated from each other by the intervening soluble polymer component in the transverse cross-section of the composite fiber. The composite fiber is characterized in that the soluble polymer component is a polyester comprised of 80 to 97% by mole of ethylene terephthalate units and 3 to 20% by mole of ethylene 5-sodium-sulfoisophthalate units, and the relatively insoluble polymer component is a fiber-forming polyester and/or polyamide.

Separable composite fiber and process for producing same

Disclosed is a bulky yarn made from a thermoplastic multifilament yarn. Each of the individual filaments forming the yarn has a randomly varying thermal shrinkage along its length. The filaments in the cross-section of the yarn also have randomly varying thermal shrinkages. The bulky yarn forms a plurality of loops having a stable and compact configuration, while the number of filament slack portions which project outwardly from the yarn surface is significantly decreased. A method for producing a bulky yarn possessing the above-mentioned construction is also disclosed. In the method, individual filaments forming the multifilament yarn are interlaced with each other, before or after which the yarn is subjected to a so-called random heat treatment. The interlaced and randomly heat-treated yarn is supplied at an over-feed condition to a fluid turbulent flow region which causes the individual filaments to form a plurality of loops and entanglements, and then the yarn is wound onto a package.

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Mishima, Japan

Yoshiaki Sato