Unitika Ltd.

Takaaki Matsuo

Kazushige Kojima

Keizo Kyuda

Katsumi Yasuzuka

Mitsunobu Satoh

Hachiro Fujiwara

A process for forming an ultra-high molecular weight nylon 6 by polymerizing .epsilon.-caprolactam, which comprises heating substantially anhydrous .epsilon.-caprolactam at a temperature of from 100.degree. to 200.degree. C. in the presence of (a) a main catalyst selected from a Grignard compound and a halogenated magnesium lactamate, (b) a co-catalyst selected from an acyl lactam compound and an isocyanic acid ester and (c) at least one activator selected from the group consisting of amides, sulfoxides, thioethers and phosphoric esters. According to this inventive process, an ultra-high molecular weight nylon 6 can be produced within a short period of time, making use of industrially advantageous compounds which are stable in air, hardly dangerous and inexpensive. Being free from cross-linkings, the ultra-high molecular weight nylon 6 obtained by the process of this invention is soluble in various solvents and is useful as a starting material for the production of high strength and high modulus materials.

Anhydrous polymerization of caprolactam with catalyst, cocatalyst and

A yarn comprising thermoplastic synthetic staple fibers or thermoplastic synthetic staple fibers and continuous filaments, in which the individual fibers constituting the yarn contain twisted crimps and having cross-sectional surfaces with a markedly flattened portion, in which the staple fibers contained therein have broken ends comprising mainly portions flattened to a lesser degree, a plurality of fibers having this structure uniformly and alternately forming the surface and inner layers of the yarn and being intertwined in a truly twisted state or in a substantially non-twisted state at fluffs formed of the broken ends of the individual fibers, and a process for producing a yarn which comprises drawing an undrawn yarn comprising multifilaments of a thermoplastic synthetic polymer and having substantially the same break elongation, in a twisted state at an elevated temperature thereby to remarkably flatten portions of the individual filaments which appear on the outer layer of the yarn, and immediately detwisting the yarn to break a part or all of those portions of the filaments which are flattened to a lesser degree, followed by taking up the yarn.

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Kyoto, Japan

Takaaki Matsuo