Patent GB-1015427-A (GB)
Title: Filaments for non-woven fabrics
Inventor: MCINTYRE JAMES ERIC
IPC: D04H1/54
Filed: 1962-08-30
Abstract: A non-woven fabric comprises non-crystalline undrawn polyester filaments bonded together at their points of contact by at least partly crystalline polyester derived from the polyester filaments. Non-crystalline undrawn polyester filaments are defined as filaments or fibres whose X-ray diffraction spectrum shows only diffuse scattering without the presence of discrete X-ray diffraction spots or circles, although the diffuse halo may vary in intensity at different angles from the equator to the meridian of the photograph when taken on a flat plate X-ray camera.  Other filaments or fibres may be placed in contact with the undrawn filaments.  The non-crystalline undrawn polyester filaments are treated with a liquid which is a solvent for amorphous polyester but does not dissolve the crystalline polyester when placed in contact with it at the temperature of application.  The filaments are brought into contact with each other at a temperature above 0 DEG C. while the surface is wet or swollen by the solvent.  The solvent is then evaporated to leave a bond between the filaments, the bond consisting of crystalline or at least partly crystalline polyester derived from the filaments.  The fabric may be drawn by hot stentering.  Specified filaments are polyethylene terephthalate filaments having a birefringence of not more than 50 x 10-3 and a copolymer of polyethylene terephthalate and polyethylene sebacate. Specified solvents are methylene chloride, chloroform, ethylene dichloride, 1, 2-dichloroethylene, symtetrachloroethane, e.g. 1, 1, 2, 2-tetrachloroethane, sym-tetrabromoethane, bromoform, chloroacetonitrile, dioxan, dimethyl formamide, m-cresol, aniline, m-toluidine, 2-chloro-4-methyl aniline, concentrated nitric acid, o-chlorophenol, dichloroacetic acid and concentrated sulphuric acid. A mixture of solvents with non-solvents may be used.  The solvent may be applied in the form of an emulsion in water; by coating the filaments when placed in contact with a rotating wheel passing through a bath of the solvent and carrying a film of solvent on its surface; passing the filaments through a bath of the solvent; spraying the solvent on to the filaments; dripping the solvent on the threadline of the filaments; or contacting the filaments with a wick dipping into the solvent.  The filaments may be laid down while the surface is wet or swollen by the solvent to form a fabric by winding them up or laying them on a shaped surface, such as a bobbin, a large cylinder or a belt using a suitable traverse motion.  The rate of traverse may be varied to vary the angle between the filaments and different angles of laydown may be obtained on the same surface.  The traverse motion may be provided by one or more rotating guides which lay down the filaments, e.g. in a trochoidal manner.  The undrawn filaments may be laid down cross-wise on to a warp of similar undrawn fibres.  The surface on which the filaments are to be deposited may be moved with a jigging action in a direction other than the general direction of motion such that a point on the surface describes a shape selected from a sinusoidal, cycloidal or trochoidal path.