Patent GB-1309295-A (GB)
Title: Process of manufacturing synthetic superfine filament bundles which are similar in their properties to collagen fibres
IPC: B29C48/04
Filed: 1970-05-06
Abstract: 1309295 Superfine filaments and microfibres TORAY INDUSTRIES Inc 6 May 1970 12 May 1969] 21812/70 Heading B5B [Also in Division D1] A process for manufacturing synthetic superfine filament bundles which are similar in their properties to collagen fibres comprises the steps of (1) forming an "island-in-a-sea" type composite filament 20 (Fig. 2) from a polymeric material for forming a sea constituent 21 and a blended polymeric composition for forming a plurality of island constituents 22, said island constituent consisting of at least two different polymers, at least one of which forms numerous short-length micro-fibres (dispersed microfibre component) 24 (Fig. 5) dispersed at random in another component (matrix component) 23 and is between 7 and 93% by weight of the island composition; (2) selectively removing the sea constituent, suitably by dissolution, to leave a bundle of island constituent superfine filaments 26, and (3) selectively removing at least one of the island constituents, again suitably using a solvent, to convert the superfine filament bundle into either a bundle of microfibres (by removal of matrix component) or a bundle of superfine porous filaments (by removal of the dispersed component). The sea constituent polymer and the microfibre component polymer of the island constituent may be the same polymer, may be removed in the. same step and preferably are chosen from the group consisting of polystyrene, polyethylene and polyvinyl alcohol. The matrix component polymer is preferably one or more of the group consisting of polyamides, polyesters, polyolefines or acrylic polymers. At least one of the sea constituent polymers may be selected from so-called adhesive polymers, preferably of polyurethane, which are effective for adhering the resultant bundles of microfibres or superfine porous filaments to each other and is from 7% to 85% by weight of the sea constituent. The  adhesive polymers may be activated by dis-  solving them in a solvent, by swelling them with  swelling agents or by heat activation.  Example 1 relates to the spinning of "islandin-a-sea" type conjugate filaments using polystyrene as sea constituent and polyethylene terephthalate (matrix component) and polyethylene oxide (dispersed microfibre component) as islands. The spun filaments were drawn at a ratio of 2À8 using a heated pin, treated with toluene to dissolve out the sea constituent and converted to porous superfine filamentary bundles by dissolving out the polyethylene oxide with trichloroethylene. Examples 2-5 relate to the same treatment applied to filaments in which the sea constituent and the dispersed microfibre component were the same as each other, i.e. a copolymer of styrene and methylmethacrylate, and were removed from the nylon 6 matrix component simultaneously by use of trichloroethylene. Other examples relate to similar processes, most of which also involve crimping of the filaments prior to treatment with solvent and forming the filaments into webs of felt-like material in which the filaments are adhered to each other by means of the aforementioned adhesive polymeric constituents. (For details see Specification D1). Reference has been directed by the Comptroller to Specification 1,171,843.