GB888691A - Polyurethane products - Google Patents

Abstract

A process for the production of foamable fluid polyurethane prepolymers containing unreacted NCO groups comprises reacting a polyalkylene ether, a polyalkylene ether prepared by the addition of an alkylene oxide to one or more organic polyfunctional compounds, or a mixture of one or more polyalkylene ethers with one or more organic polyfunctional compounds, with an organic polyisocyanate in an NCO:OH ratio less than 1 to produce a polyalkylene ether urethane and reacting the latter with a further quantity of an organic polyisocyanate in an NCO:OH ratio of greater than 1, said process being effected under anhydrous conditions. The products are foamable fluid prepolymers which have a stable viscosity (e.g. 5,000 to 10,000 cP at 25 DEG C.) even on prolonged heating. Preferably an NCO:OH ratio between 0,1 and 0,95, especially between 0,3 and 0,8, is employed in the first stage. As catalysts tripropylamine, triethylamine, ethyl morpholine, caprolactam, a -pyrrolidone or iron acetylacetonate are specified. Acids, acid chlorides or anhydrides may also be present. These catalysts or those disclosed in Specifications 769,680 and 769,682 are also useful in the second stage of prepolymer preparation. Additional polyisocyanate may be added to the prepolymer before the foaming step, as may accelerators and emulsifiers. The polyethers to be employed may be of the formula HO(RO)nX where R is an alkylene radical, X may be hydrogen or an alkylene amine, alkylene N-alkylamine, alkylene hydroxyamine or an alkylene N-aryl amine and n is an integer. Addition products of alkylene oxides with polyfunctional alcohols, amino alcohols or amines such as aniline, ethylene diamine, tetramethylene diamine are also suitable. In the first or second stage of the process there can also be mixed with the polyalkylene ether minor amounts of, e.g. 1,4-butylene glycol, trimethylol propane, pentaerythritol, hydroxyethylaniline, ethanolamine, N-ethylethanolamine or ethylene tetramethylene or hexamethylene diamine. Di- and tri-isocyanates are listed. In Example (1) a linear polypropylene ether is reacted in the presence of benzoyl chloride and iron acetylacetonate with toluylene 2:4- and 2:6-diisocyanates at an NCO:OH ratio of 0,6. The product is reacted with further diisocyanate to give a prepolymer containing 8,18% -NCO. This is converted to a foam by adding water, dimethyl-(3-ethoxypropyl) amine and a methylpolysiloxane. In generally similar processes (2) a mixture of the polypropylene ether and a glycerol/propylene oxide reaction product is used; (5) trimethylol propane is added at the second stage; (6) polyethylene ether glycol is used as starting material; (7) polyepichlorhydrin is used as starting material. Uses: crash pads, insulation, sponges, scrubbing pads, paint rollers, polishing pads, underlays.ALSO:A process for the production of foamable fluid polyurethane prepolymers containing unreacted NCO groups comprises reacting a polyalkylene ether, a modified polyalkylene ether prepared by the addition of an alkylene oxide to one or more organic polyfunctional compounds or a mixture of one or more polyalkylene ethers with one or more organic polyfunctional compounds, with an organic polyisocyanate in an NCO:OH ratio less than 1 to produce a polyalkylene ether urethane and reacting the latter with a further quantity of an organic polyisocyanate in an NCO:OH ratio of greater than 1, said process being effected under anhydrous conditions. The products are foamable fluid prepolymers which have a stable viscosity (e.g. 5000 to 10000 cp at 25 DEG C.) even on prolonged heating. Preferably an jNCO:OH ratio between 0,1 and 0,95, especially between 0,3 and 0,8, is employed in the first stage. As catalysts tripropylamine, triethylamine, ethymorpholine, coprolactam, a -pyrrolidone and iron acetylacetonate are specified. Acids, acid chlorides or anhydrides may also be present. These catalysts or those disclosed in Specification 769,680 and 769,682 are also useful in the second stage. Additional polyisocyanate, and accelerators and emulsifiers may be added to the prepolymer before the foaming step. The polyethers to be employed may be of the formula HO(RO)nX where R is an alkylene radical, X may be hydrogen or an alkylene amine, alkylene N-alkylamine, alkylene hydroxy-amine, or an alkylene N-aryl amine and n is an integer. Addition products of an alkylene oxide with polyfunctional alcohols, amino alcohols or amines such as aniline, ethylene diamine, tetramethylene diamine are also suitable. In the first or second stage of the process there can also be mixed with the polyalkylene ether minor amounts of e.g. 1,4-butylene glycol, trimethylolpropane, pentaerythritol, hydroxyethylaniline, ethanolamine, N-ethylethanolamine or ethylene, tetramethylene or hexamethylene diamines. Di-and triisocyanates are listed. In Example (1) a linear polypropylene glycol ether is reacted in the presence of benzoyl chloride and iron acetylacetonate in benzene with toluylene 2:4- and 2:6-diisocyanates in an NCO:OH ratio of 0,6. The product is reacted with further diisocyanate to give a prepolymer containing 8,18% NCO. This is converted to a foam by adding water, dimethy-(3-ethoxy propyl)-amine and a methylpolysiloxane. In generally similar processes (2) a mixture of the polypropylene ether glycol and a glycerine/propylene oxide addition product is used; (5) trimethylol propane is added at the second stage; (6) and (7) polyethylene ether glycol and polyepichlorhydrin, respectively, are used as starting material. Uses. Crush pads, insulation, sponges, scrubbing pads, paint rollers, polishing pads, underlays.