GB1105968A - Webs of crimped continuous filaments - Google Patents

Abstract

1,105,968. Laminates. CELANESE CORPORATION. 20 Nov., 1964 [21 Nov., 1963; 13 July, 1964 (2)], No. 47321/64. Heading B5N. [Also in Divisions A4 and D1] A diaphanous fibrous web, as may be employed to make non-woven fabrics or laminated sheet materials, is composed of crimped continuous filaments all lying generally in the same direction and held together by entanglements due to the crimps and the departure from the general direction of minor, angularly disposed, short lengths of the filaments. The web has an average air space per filament i.e. the average space between the filaments of the web measured on a line in the plane of the web perpendicular to the general direction of the filaments and assuming all filaments are arranged in a single plane with no crossing filaments, which is positive and at least five times the average filament diameter. The filaments may be of regenerated cellulose, cellulose acetate, triacetate, propionate or acetate propionate, polyacrylonitrile and copolymers of acrylonitrile, polyamides such as nylon 6 or 66, polyesters e.g. polyethylene terephthalate or olefinic polymers and copolymers e.g. polypropylene. At the first stage of continuous web formation, a crimped tow is opened while the crimp in individual filaments is moved out of registration with crimps in adjacent filaments by the use of apparatus, such as described in Specification 1,001,813, in which the running tow is passed between a pair of rolls at least one of which has an interrupted surface so that the filaments are only gripped between the rolls in regions alternating with other regions where the filaments are not so gripped, the particular filaments gripped changing repeatedly during passage of the tow between the rolls so that different groups of filaments are gripped and relaxed. At the second stage, the opened tow is spread to increase its width e.g. by 1À5 to six times, by a force, as may be provided by an air blast or upwardly curved bars of increasing length forming a spreader, applied in one or more successive stages to the tow uniformly across its width so as to move apart the individual filaments. The spreading may be effected to an optimum extent i.e. such that if further spreading is attempted, while the length of the web is maintained constant, the web strongly resists such spreading and returns to its previous width. The spreading action may be enhanced by application of a tow finish e.g., an aqueous emulsion of a hydrophobic silicone containing little or no antistatic agent, before or after tow crimping, in order to form a film around each fibre. Web products.-In the manufacture of yarns or ropes, the web is subdivided e.g. by hot wire or roller cutters, into narrow bands. The web may be converted into foraminous and/or permanently heat-set, patterned fabric with spaced openings and/or projections as may be formed by rollers or air jets. Layers, plies, folds or laps of the web may be inseparably united to form sheet materials or battings and the web or sheet material &c. may be incorporated in pillows, cushions or upholstery, with or without needling. The web &c. may be impregnated with adhesive, plasticizer, plastic bonding agent e.g. an elastomeric polymer, or solvent applied uniformly or at regularly or irregularly distributed spots or areas by sprays, whirling discs, baths or (including intaglio rollers). The web &c. may be laminated to (tissue) paper, woven scrim or cheesecloth, knitted tricot or netted fabric, staple fibre web, sponge rubber, leather or plastic sheeting, the assembly being consolidated by bonding agent, fusion and/or sewing and/or needling. The adhesives, bonding agents &c. may be triethyl citrate, dimethoxy ethyl phthalate, methyl phthalyl ethyl glycollate, glycerol triacetate, acetone (for acetate filaments) chloral hydrate, aqueous vinyl chloride polymer emulsion, polyvinyl acetate, elastomeric polyurethane, a copolymer of butadiene and acrylonitrite, polystyrene, vinyl pyridine, methyl methacrylate, a homopolymer of butadiene or isoprene or chloroprene, or an elastomeric ethylene propylene copolymer deposited, as by use of blowing or foaming agents or use of rubber latices followed by coagulation, perhaps vulcanization and curing followed perhaps by a thin coating of a tough polymer e.g. polyethyl acrylate, polyvinyl chloride or a polyurethane, so that the final material remains porous or microporous. The top surface of such e.g. laminated, material may have a high concentration of fibrous material, as may result from selective shrinking. Forming a single web.-As shown in Fig. 1, a crimped tow 10 from a bale 11 is fed across a guide 12, through a banding jet 13, through an opening device 14 which includes two (or more) pairs of steel rolls 15 and 16, the former having two sets of oblique ridges and grooves which wind oppositely and helically about the roll from the centre towards the ends and the latter having a smooth, resilient cover, thence over a spreader comprising arched bars 17a-17e. A bulky, corrugated material is obtained by feeding the web into a stuffing-box, Fig. 3 (not shown), at the entrance of which the web is acted upon by reverse folding means, and is stabilized by heat-setting or adhesive or by fusion of filaments at their points of intersection. Opening and spreading tow.-In the opening and spreading apparatus of Fig. 14, a tow band from a bale 64 passes, in a banding jet 65, between a cylinder 66 (having a slit running lengthwise of the cylinder at its highest point) and a curved baffle 67. Air under pressure emerging from the slit has a component opposing the forward motion. The tow passes around stationary, adjustably mounted tensioning bars 68, 69, into the nip of rubber-surfaced rolls 70, 71, thence to the nip between a rubbersurfaced roll 72 and a threaded, steel draw roll 73. Then the tow passes through a slot in an air spreader 74 to which air under pressure is supplied from an underlying plenum chamber, Figs. 15 and 16 (not shown), through tapered air slits angularly arranged or running perpendicular to the direction of movement of the tow, Fig. 18 (not shown). The web is pulled through the spreader by rolls 81, 82, and passes to another air spreader 83 from which the web, at the full desired width, is pulled by rolls 84, 85, and falls in a freely hanging shallow catenary 86 and is guided by idler roll 88 on to belt conveyer 87. Making yarns and ropes.-In the production of yarns, Figs. 23 and 24, a single lightweight web emerging from the roll 85 (see Fig. 14) passes to a slitting zone comprising a roll 103 having V-shaped grooves 104 separated by sharp parallel ridges 105 and a hot wire apparatus 106 comprising electrically heated wires 107 with operative portions penetrating the web, there being one wire 107 for each groove 104 and wires are aligned with the ridges. The web may be slit by a series of rotating Knives (not shown). Narrow bands, suitable for conversion to yarns or ropes by heat-setting and/or twisting, may alternatively be produced by subdivision of a web 10<SP>1</SP> in the apparatus of Fig. 5 comprising a housing 30 of electrical insulation material carrying plates 31, 32, along the exit slot 30a. The plates are maintained at an electrical potential of the order of 100,000 volts and the electrostatic field generated across the slot collects the filaments into the desired number of bands 29. Cutters (not shown) remove straying filaments. Making composite tows and laminated strucures.-As shown in Fig. 6, the web 10<SP>1</SP> is fed to a folder, lapper or cross-lapper apparatus 33; reciprocating at a controlled speed above and along A or across B on endless conveyer belt 34, to form a multiply web 36 which is rolled up lengthwise or widthwise for subsequent use in pillows &c. or to receive an application of bonding agent (particularly if such was not previously applied) or to be consolidated as by stitching and/or needling either cross-wise at regular intervals or in a single or multiple zig-zag pattern, Figs. 8 and 9 (not shown), e.g. to achieve a quilted effect. The web(s) 10<SP>1</SP> or 36 may be laminated to similar or different webs, Figs. 7 and 11 (not shown), the filaments in adjacent layers or web sections being transverse e.g. at right angles, to one another. The laminated structure may be consolidated by adhesive (pre- or post-applied) or by stitching and/or needling in the same manner as applied to a single web 36. A laminar structure, Fig. 13 (not shown), is formed by feeding at least one bonded or unbonded web 10<SP>1</SP> into a stuffer box 22, Fig. 12, through folding apparatus 23 and, simultaneously therewith, two or more bands of sheet material, as at 46<SP>1</SP>, 46<SP>11</SP>, are passed into contact with opposite faces of the web and are bonded thereto by adhesive previously applied to the web and/or sheet materials. Continuously cutting webs into lengths.-A single or composite web W may be severed into required lengths by a cutter 57, Fig. 10, comprising endless belts 58, 59, with reciprocating knives 60, 61, and associated with an expander 62 designed to take up slack in the web resulting from stops in the feed during each cutting operation.