Patent GB-928325-A (GB)
Title: Process for making vinyl chloride polymer cellular materials
IPC: C08J9/06
Filed: 1961-12-01
Abstract: A method for making a cellular material from a vinyl chloride polymer plastisol composition comprises adding to the plastisol composition an isocyanate having the structural formula R(NCO)x where R is an organic radical free of reactive hydrogen and x is an integer, water and a chemical blowing agent in the form of sodium, potassium, rubidium or cesium borohydride, allowing the chemical blowing agent and water to react to expand the plastisol composition into a cellular mass, and heating the expanded plastisol composition to gel and fuse it.  The isocyanate acts to delay reaction between the water and the metal borohydride blowing agent.  The isocyanates listed include, as well as monomeric compounds, reaction products of excess di- or trisocyanates with polyesters or polycompounds, reaction products of excess di- or triisocyanates with polyesters or polyethers. The components of the plastisol can be the same as those used in the process of Specification 799,750.  The isocyanate may be added to the plastisol or be mixed with the plasticizer.  In Example (1) a solution of potassium borohydride in water adjusted to pH 11 is added, together with toluene diisocyanate to a plastisol of a vinyl chloride polymer in dioctyl phthalate.  Finally phthalic anhydride in didecyl phthalate is mixed in.  The composition is poured into a mould, and after expansion, is gelled and fused at 350 DEG F.  In other, rather similar examples, the isocyanates used are 65/35 or 80/20 mixtures of 2,4- and 2,6-tolylene-diisocyanates, "Adiprene L" (Registered Trade Mark), and a polymeric material resulting from the reaction of polypropylene glycol, a 65/35 mixture of tolylene 2,4- and 2,6-diisocyanates and hexane triol.  In some examples the sodium borohydride is used as part of a composition together with water, sodium hydroxide, boric acid and methanol.ALSO:A method for making a cellular material from a vinyl chloride polymer plastisol composition comprises adding to the plastisol composition an isocyanate having the structural formula R(NCO)x where R is an organic radical free of reactive hydrogen and x is an integer, water and a chemical blowing agent in the form of sodium, potassium, rubidium or cesium borohydride, allowing the chemical blowing agent and water to react to expand the plastisol composition into a cellular mass, and heating the expanded plastisol composition to gel and fuse it.  The isocyanate acts to delay reaction between the water and the metal borohydride blowing agent.  The isocyanates listed include, as well monomeric compounds, reaction products of excess di- or triisocyanates with polyesters or polyethers.  The components of the plastisol can be the same as those used in the process of Specification 799,750.  The isocyanate may be added to the plastisol or be mixed with plasticizer.  In Example (1) a solution of potassium borohydride in water adjusted to pH 11 is added, together with toluene diisocyanate, to a plastisol of a vinyl chloride polymer in dioctyl phthalate.  Finally phthalic anhydride in didecyl phthalate is mixed in.  The composition is poured into mould, and after expansion, is gelled and fused at 350 DEG F.  In other, rather similar examples, the isocyanates used are 65/35 or 80/20 mixtures of 2, 4- and 2, 6-tolylene diisocyanates, "Adiprene" L (Registered Trade Mark) and a polymeric material resulting from the reaction of polypropylene glycol, a 65/35 mixture of tolylene 2, 4 and 2, 6- diisocyanates and hexane triol.  In some examples the sodium borohydride is used as part of composition together with water, sodium hydroxide, boric acid and methanol.