Patent GB-941931-A (GB)
Title: Manufacture of bulked yarn from synthetic continuous thermoplastic filaments
IPC: D02G1/16
Filed: 1960-02-24
Abstract: 941,931. Spinning yarns. MONSANTO CHEMICAL CO. Feb. 24,1960 [March 9, 1959], No. 6521/60. Headings D1F and D1W. The filaments of a continuous thermoplastic e.g. nylon, filamentary yarn are crimped (and the yarn rendered stretchable and/or uniformly bulked) by passing the yarn through a zone of non-turbulent compressed air heated to a temperature not exceeding 232‹C. A stream of the air may flow in a straight path at a velocity proportional to the amount of compression e.g. four times atmospheric, employed. The yarn, preheated by molecular orientation, may be introduced at an acute angle into the stream in a coaxial path and at a velocity proportional to the temperature of the heated air and the length of the stream. The yarn may be withdrawn from the stream at an angle of 90 degrees at a speed 35-75% less than it was fed thereto so that it forms an unrestricted arch at the point of withdrawal. Such withdrawn yarn is subjected to a hot aqueous medium e.g. steam or water flowing in a tube, while in a tensionless state, cooled as by contact with cold air or a cooling surface of a metal plate or bar, and collected without (further) twisting. Each filament has elastic sinusoidal crimps, randomly spaced along its length, and of irregular and varying amplitude with rounded apices and in one or more planes of the filament in a randomly reversed helical pattern, and the filament is free of loops and twist. The filament may be of circular or non-circular cross-section e.g. fins joined to, and disposed radially on, a body as in X- or Y-form, in which case each fin has the twist pattern along its length and the twist in each fin is irregular with respect to the twist of each other fin. The filaments may be of polyamides such as polyhexamethylene adipamide, polyesters such as polyethylene terephthalate, polyolefines such as polypropylene and polyethylene, polyurethane, polyacrylonitrile, copolymer of vinyl acetate and vinyl chloride, copolymer of vinylidene chloride and a minor proportion of mono-olofinic compounds copolymerisable therewith such as vinyl chloride, mixtures and/or copolymers thereof. The yarns may be twisted or untwisted and yarns having different compositions and deniers may be combined before being processed. As shown in Fig. 1, yarn 10 withdrawn from a package 11 passes through a gate tensioner 13, between controllably driven thread-advancing rolls 14, into one limb 16 of a valve-controlled fluid jet 15 communicating with a main bore in which the yarn is entrained in a stream of compressed air supplied from a reservoir 18 served by a compressor 17 and heated within a chamber 21 by an electrical element 22 and passing through an insulated conduit 25. Yarn withdrawn from the stream passes through guides 27, 28, and traverse guide 30 and is wound into a package 33 by a roll 32 the peripheral speed of which is less than that of roller 14. A multiple assembly of jets may be supplied from a single source of compressed air. Tension may be applied and/or controlled by snubbing bar(s) co-operating with rollers and the yarn may be stretched continuously prior to crimping: withdrawn yarn may be deposited by a traversing piddler on to a moving, perforated, endless belt which passes successively through steaming and drying compartments of a cabinet, Figs. 2 and 3 (not shown).