GB900867A - Sandpaper - Google Patents

Abstract

900,867. Abrasive paper. RIEGGER, G. C., and SMITH, R. M. July 27, 1960 [July 27, 1959], No.26177/60. Class 60. An abrasive paper comprises a reinforced paper backing web 6 comprising a continuous network of Kraft-type wood pulp fibres 11 arranged in overlapping crossing relationship .with one another so as to define a multiplicity of interstices 12 between them, and a multiplicity of thermoplastic reinforcing members 13 distributed substantially uniformly throughout the web in (bonding relation with the ,wood ,pulp fibres and larger than the Same, said rejnforcing members being flexible and tough and defining a multiplicity of spaces 14 between them, having a flexible moisture resistant barrier coating 7 on one side of said web, a layer 8 of grit supporting varnish on the side of said barrier.coating.opposite to said web, and a multiplicity of abrasive grits 9 imbedded in said varnish. The bonding members may be at least five times larger in cross-sectional area than the wood pulp fibres, may be between 1 and 35 mils. in cross dimension and may be of elongate shape having a length to width ratio of at least 2 to 1. The reinforcing members may be present in the web in an amount of between 2 and 60% based upon the combined dry weight of the wood pulp fibres and reinforcing members. The reinforced paper backing may have a weight of 40 to 150 pounds per ream of 480 sheets, 24 inches wide and 36 inches long. The abrasive paper may include rubbery binder solids portions distributed substantially uniformly throughout the web, said portions forming a multiplicity of bonds between the wood pulp fibres in the individual spaces between the reinforcing members. Specified binder solids, which may be applied as an aqueous dispersion or deposited from a solution in a volatile organic solvent, are natural or synthetic rubber such as the polymers, copolymers or tripolymers of conjugated dienes, e.g. butadiene and its homologues, butadieneacrylonitrile, vinyl chloride polymers, chloroprene rubber, and copolymers of vinyl chloride with, for example, vinylidene chloride and vinyl acetate. The binder may be mixed with the sodium salt of ethylene diamine tetra acetic acid. The thermoplastic reinforcing members may essentially comprise a long chain polymeric material such as polyamide, e.g. nylon, polyvinyl chloride, polyethylene, polyurethane, polystyrene, polyvinylidene cyanide, plasticized cellulose acetate and plasticized ethyl cellulose. Moisture-resistant barrier coating material specified is polyvinyl chloride plasticized with a copolymer of butadiene. Abrasives specified are sand and silicon carbide.