GB984300A - Polyurethane foam product and method of making same - Google Patents

Abstract

Open-cell polyurethane foams are stiffened by impregnating the foam in an organic polyisocyanate or solution of organic polyisocyanate and thereafter drying the product. The foam may be first impregnated with a weakening agent, e.g. caustic soda and mechanically worked to weaken its cell wall structure. The product may have a density in the range 0.75-2.4 pounds per cubic foot, and may be coated after stiffening with an organic coating composition, e.g. resins, waxes or rubbers which covers the internal and external cell surfaces. At least one defined region of the foam may have a rigidity substantially in excess of that of the remainder, obtained by restricting the action of the polyisocyanate to a defined region of the foam by masking. Preferred polyisocyanates are arylene diisocyanates, e.g. the toluene diisocyanates. After treatment any excess polyisocyanate may be removed by evaporation at 20-40 DEG C. or by heating to 160 DEG F. or reduced pressure. Plasticizers, e.g. cresyl diphenyl phosphate, tricresyl phosphate; dibutyl phthalate; di-(2-ethyl hexyl)phthalate; diethyl, dibutyl and polypropyl adipates may be added to the polyisocyanate. Solvents may be aliphatic hydrocarbons, chlorinated hydrocarbons, ketones and aromatic hydrocarbons. In examples, polyurethane foams derived from polyethers and polyesters were repeatedly compressed in polyisocyanates at room temperature for 1-5 minutes and were then airdried.ALSO:Polyurethane foams (which have been stiffened by immersion in an organic polyisocyanate followed by drying (see Division C3), are coated on their internal and external cell surfaces with an organic material, e.g. ethyl or nitro cellulose, chlorinated rubber, and coumarone, epoxy, polyethylene, fluoroethylene, furan, melamine, phenolformaldehyde and hydrocarbon resins, also synthetic rubbers, silicones, urea formaldehyde resins and polymers of styrene, vinyl chloride, vinyl chloridevinyl acetate, terpenes and waxes. The coating compositions are applied to the stiffened foam by immersing the foam in a solvent containing the coating composition and compressing and decompressing till saturation occurs. Plasticizers may be included in the coating composition. In an example a stiffened polyurethane foam was coated with a solution of a polyvinyl chloride-polyvinyl acetate copolymer in tetrahydrofuran.