One-component polyurethane foam in cans, e.g. for building applications, contains a prepolymer derived from a polyisocyanate obtained by reacting excess di-isocyanate with polyol and then removing the excess monomer

摘要

A prepolymer for use in 1-component polyurethane foam in cans is made by reacting polyols with a stoichiometric excess of a monomer-free polyisocyanate which is obtained by reacting a di-isocyanate with less than the stoichiometric amount of polyol and then removing the excess di-isocyanate. One-component polyurethane foam made by depressurising a prepolymer (I) which is obtained by reacting a monomer-free polyisocyanate (II) with a stoichiometric deficit of polyols and which is contained in a pressure can with a physical blowing agent. The polyisocyanate used (II) is obtained by reacting a di-isocyanate with less than the stoichiometric amount of polyol and then removing the excess di-isocyanate. Independent claims are also included for the following: (1) a prepolymer (I) as described above for the production of 1-component polyurethane foam in cans; (2) a method as described above for the production of (I); and (3) a method as described above for the production of 1-component polyurethane foam in cans.