Patent GB-1105482-A (GB)
Title: Improvements relating to flexible sheet materials
Inventor: CLARKE DENNIS IVOR
IPC: D06N3/00
Filed: 1964-02-27
Abstract: A flexible sheet material is provided, on at least one surface, with a layer comprising microscopic empty hollow particles collapsible on compression.  The microscopic hollow particles may be of unicellular or polycellular structure and may be spherical bodies of a synthetic resin composition such as a urea-aldehyde resin composition, e.g. urea-formaldehyde, or a phenol-aldehyde resin composition such as phenol-formaldehyde.  The layer of microscopic hollow particles may also comprise a binder such as graft polymer of methyl methacrylate and natural rubber, thermoplastic polyurethanes and vinyl chloride polymer and copolymer coating compositions.  The layer may be coated on the flexible sheet material as a preformed sheet or as a thickened aqueous dispersion which is subsequently dried.  The flexible sheet material may be of a wide variety of types.  Examples are: a leather-like sheet material comprising a consolidated matt of interpenetrated, crimped continuous fibres bonded together with an elastomeric or resinous binder composition optionally having a layer of non-woven staple fibres, e.g. polypropylene staple fibres, needled on at least one surface of it and bonded to the continuous fibres with an elastomeric or resinous binder composition, or having a woven fabric bonded to one surface of it with a resinous or elastomeric bonding agent, and a surface layer of a resinous or elastomeric composition on the surface of the woven fabric remote from the matt, a fibrous material bonded together by a natural or synthetic rubber, and a layer of a polymeric composition coated on the surface layer to which the layer of hollow particles is applied.  The fibrous material may be nylon filaments.  The binder compositions can be of natural or synthetic rubber such as polyurethane, butyl, styrene-butadiene copolymer, polychloroprene rubbers.  The flexible sheet material may contain other additional surface layers such as a varnishing layer applied on top of the layer(s) of microscopic hollows particles, e.g. a pigmented acrylic resin emulsion.  Such layers may be applied before or after the flexible sheet material has been embossed.  In the Examples: (2) a preformed film comprising urea-formaldehyde microballoons and a graft copolymer of methyl methacrylate and natural rubber and which is shiny and smooth on one surface but matt on the other is placed with its matt surface against a square sample of an artificial leather, and the laminate compressed and embossed, a pigmented acrylic finish being then applied.  The artificial leather comprises a needled web of continuous bulked 6-denier nylon and 3-denier polypropylene staple fibre impregnated with an aqueous composition comprising natural rubber, sulphur, di-beta-naphthyl paraphenylenediamine, zinc dibutyl dithio-carbonate, potassium oleate, zinc oxide, ammonium chloride, and dried with the face consisting mainly of polypropylene fibres in contact with a smooth stainless sheet. The face of the artificial leather was reinforced by brushing with a further quantity of the impregnating composition omitting the ammonium chloride gelling agent; (3) a film of polyethylene terephthalate is coated with a blend of an aqueous dispersion of urea-formaldehyde hollow bodies with the disodium salt of methylene di-naphthalene sulphonic acid in solution, natural rubber latex, aqueous dispersions of sulphur, zincmercaptobenzthiazole, zinc diethyl dithiocarbonate, zinc oxide, di-beta-naphthyl-paraphenylene-diamine, and lamp black with an ammonium polyacrylate thickener.  The coating is dried, cured and the sheet embossed.  It stated that the embossed sheet can be secured to the artificial leather mentioned in (2).