Patent GB-981910-A (GB)
Title: Bonded non-woven fibrous structures
Inventor: MARRINAN HENRY JAMES
IPC: D04H1/482
Filed: 1962-12-28
Abstract: A non-woven fibrous fabric in which the fibres are bonded by means of a polymer deposited from a stabilized dispersion of said polymer in an organic solvent (see Divisions D1 and D2) is coated, e.g. to simulate leather.  The coating may be applied in the form of a "plastisol", e.g. as a dispersion of the coating substance in a plasticizer, as a dispersion of a polymeric coating substance in an organic solvent the dispersion being stabilized by a graft or block copolymer, the organic solvent containing optionally a plasticizer for the polymer, or as an aqueous dispersion or a solution.  The coating may be applied by spraying or by a knife spreading or other technique.  The fabric may be heated to cure the material of the coating.  In Example 1 a fabric comprising polyethylene terephthalate and polypropylene fibres bonded with polyvinyl chloride was coated with a polyesteurethane coating.  In Example 2 similar fabrics were coated with polyvinyl chloride, in the first case using a "plastisol", and in the second case using a diluted stabilized dispersion in light petroleum.  In Example 11 a bonded fabric was coated on both surfaces with plasticized polyvinyl chloride to provide a material suitable for use as conveyer belting. Specification 980,633 is referred to.ALSO:A process for producing a bonded fibrous material comprises impregnating a bat, mat or web of fibres with a dispersion in an organic solvent of a polymer which is stabilized by a compound which is a block or graft copolymer and which has two constituents one being solvatable by the organic solvent and the other being substantially non-solvatable so that it becomes identified with the dispersed particles.  The web may be formed by carding or air- or water-laying followed if desired by needling and/or shrinkage treatments, such as exposure to hot water or steam. Fibres specifically referred to include drawn and undrawn, crimped polyethylene terephthalate staple fibres and isotactic polypropylene staple fibres and mixtures thereof.  Formation of the polymer dispersion may be effected in various ways, e.g. by precipitating a preformer polymer from solution or by forming the polymer in a liquid in which it is insoluble.  The block or graft copolymer may be added as such or may be formed in situ during or prior to the formation of the main polymer or alternatively a compound comprising the solvatable constituent may be used in conjunction with a solution of the polymer said polymer having active groups to which the solvatable constituent becomes attached the stabilized polymer then being precipitated.  The organic solvent may contain a plasticizer with which the polymer may react on heating or the polymer and plasticizer may together react with a third component in the solvent.  Suitable polymers for use in forming the dispersion include plasticized polyvinyl chloride and polymers or copolymers of esters of acrylic or methacrylic acid.  Where plasticized polyvinyl chloride is used the plasticizing action may be achieved by copolymerizing another monomer, such as a vinyl ester with the vinyl chloride. Copolymers of butadiene with acrylonitrile, methyl methacrylate or styrene are particularly useful.  The nature of the solvatable constituent of the block or graft copolymer may vary in dependence upon the organic solvent employed.  If a petroleum fraction is used the solvated portion is conveniently a polymer of an acrylate or methacrylate derived from an alcohol containing six or more carbon atoms.  The non-solvatable constituent may have substantially or essentially the same composition as the main polymer dispersed in the organic solvent.  The fibrous web may be impregnated with the dispersion or the dispersion may be formed in situ in the web.  Deposition of the dispersed polymer may be effected by evaporation of the organic solvent or by coagulating the dispersion, e.g. by immersing the impregnated bath in a liquid which is compatible with the organic solvent but not with the dispersion or with the solvatable constituent of the block or graft copolymer.  The treated fibrous web may be dried and the bonding agent cured by heat treatments and the fabric may then be dyed and coated or laminated (see Division B2 or Division B5) e.g. to produce material simulating leather.  In Example 1 a polyester-urethane coating is used.  In Example 11, a coated fabric is buffed on a leather sueding machine to produce an imitation suede leather and a further sample is coated on both surfaces with plasticized polyvinyl chloride to give a material suitable for use as conveyer belting.  Specification 980,633 is referred to.