Patent GB-1260615-A (GB)
Title: Improvements in or relating to reinforcing foam sheets
IPC: C08J9/00
Filed: 1970-04-29
Abstract: 1,260,615. Fibre-reinforced foam laminates; fibre reinforced extrudate. HASKON Inc. 29 April, 1970 [30 April, 1969], No. 20710/70. Headings B5A and B5N.  A laminated sheet comprising exterior layers of foam with a layer of fibrous material laminated in the centre and suitable for use for a carpet backing is produced by forcing a molten foamable thermoplastic polymer composition through an annular die and allowing the composition to foam as a result of the pressure drop upon emerging from the die to form a foamed tube, depositing reinforcing fibrous material which has a melting point or decomposition point above the extrusion temperature of the polymer on the inside of the tube and collapsing and flattening the tube while the interior thereof is sufficiently warm to fuse the interior surface and form an integral laminated sheet. The fibrous material may be in the form of fibres, monofilaments, multifilaments or knit or woven scrim of cotton, jute, wool, asbestos, glass, viscose rayon, acetate rayon, polypropylene, nylon or polyethylene terephthalate and may be deposited on the inside of the tube by blowing precut fibres through the centre of the die and depositing them on the inside of the tube using a rotating air jet, depositing a continuous filament using a rotating air jet, feeding scrim through the die and forcing it against the inner walls of the tube using a rotating air jet, providing a rotating cutter on the face of the die to cut yarn fed through the die to the desired length and throw it uniformly against the inside walls of the tube or equipping the die with an internal mandrel which forces scrim against the inner walls of the tube. The thermoplastic polymer may be ethyl cellulose, cellulose acetate or acetate butyrate, homopolymers or copolymers of olefins, vinylidene chloride, vinyl esters of carboxylic acids, vinyl ethers, unsaturated carboxylic acids or derivatives thereof, vinyl chloride, or aromatic hydrocarbons or ring halogenated derivatives thereof, polychlorotrifluoroethylene, polycarbonates, polyoxymethylene, oxymethylene - alkylene oxide copolymers, polyurethanes, polyethylene terephthalate or polyhexamethylene adipamide. The composition may contain as primary blowing agent monochlorodifluoro methane, monochlorotrifluoromethane, dichlorodifluoromethane or dichlorotrifluoromethane and as secondary blowing agent pentane, heptane, hexane, petroleum ether, cyclohexane or cyclopentane. The composition may also contain a nucleating agent, e.g. calcium silicate, barium sulphate or silica, a gas producing compound, e.g. citric acid or sodium bicarbonate, a mixing aid, e.g. zinc or calcium stearate, a dye, pigment, stabilizer, surfactant, plasticizer, softener or flame retarder. Adhesion of glass fibres to the tube may be improved by treating the glass fibres with a diazo or azidosilane or a mixture of (a) vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ - aminopropyltrimethoxysilane, methacrylatochromium chloride, acrylic acid or phthalic anhydride dichlorophenyl phosphine or phenyl phosphinic acid, and (b) a compound of the formula in which R is an organic radical, n is 0-10 and m + n is 2-10. In Fig. 1 an extruder comprises hopper 1, extrusion screw 2, heating jacket 3 having inlets and outlets 4 and 5 for heating medium, extrusion head 6 equipped with a rotating shaft terminating with cutter blade 7 and annular die 8, several tows 9 from spindles 10 passing through circumferentially spaced openings into the extruder head 6 to cutter blades 7 which throw the fibre segments on to the interior of foam tube 11 which is progressively flattened by rollers 12 and 13 and passed through the nip of calender rolls 14 and 15.