GB1175717A - Improvements in or relating to the Preparation of Polyurethane Foams - Google Patents

Abstract

1,175,717. Polyurethane foams. KERR CHEMICALS Inc. 4 Sept., 1967, No. 40364/67. Headings C3C and C3R. Polyurethane foam is formed in situ by forming two liquid masses neither of which alone is capable of being discharged as an aerosol, confined separately in aerosol type containers and capable of being coupled in fluid flow communication for the transfer of one liquid mass into the other, for combination therewith, one of the masses including an isocyanate-terminated prepolymer and an excess of an aromatic polyisocyanate in an unreacted state, the other of the masses including a sufficient proportion of a polyol to react substantially completely with the unreacted excess of aromatic polyisocyanate, one of the masses being under an inert gas pressure sufficient to transfer it into the other of the masses for admixture therewith, at least one of the masses containing a dissolved gas or mixture of liquefied and non-liquefied gases operative to function as propellants and/or blowing agents after effecting the admixture, transferring the mass under the inert gas pressure into the other mass for combining and admixture therewith, agitating the combined masses to effect the admixture and to bring about a chemical exothermic reaction generating sufficient heat to vaporize the blowing agent and develop sufficient pressure to discharge the admixture while in a cream state as an aerosol, all of the foregoing steps being carried out in a confined system prior to final discharge of the aerosol, and discharging the cream state admixture as aerosol together with the blowing agent, at a location where curing in situ of the foamed polyurethane is to take place. In a preferred form of the invention one of the containers, the transfer can, contains a polyetherpolyol, a catalyst, a foam stabilizing agent and a blowing agent, all confined as a liquid mix under a relatively high inert gas pressure and the other of the containers, the base can, contains in liquid admixture, a polyether polyol reacted with an excess of an aromatic polyisocyanate to form a prepolymer and to leave unreacted an amount of aromatic polyisocyanate sufficient to react with the polyether polyol of the transfer can, and a dissolved gas or mixture of liquefied and non- liquefied gases such as fluorocarbons. In a specific example, the transfer can contains a polyether polyol which is a propylene oxide adduct of sorbitol, tetramethylbutanediamine as catalyst a surfactant, trichlorofluoromethane and dichlorodifluoromethane under nitrogen gas at high pressure and the base can comprises the reaction product of a propylene oxide adduct of sorbitol with an excess of toluene diisocyanate and trichlorofluoromethane. Reference has been directed by the Comptroller to Specification 1,086,609.