Flexible polyurethane foams from polymethylene polyphenyl isocyanate containing prepolymers

Abstract From the Canadian patent

Flexible polyurethane foams are made from isocyanate containing prepolymers where the isocyanate is a mixture of diphenylmethane diisocyanate (MDI) and polymeric forms of MDI. The isocyanate mixture has a functionality greater than 2Ø The prepolymer is an isocyanate capped polyol or mixture of polyols where the polyols are diols or triols having at least 50% by weight oxyethylene groups. The foams are made by reacting water with the prepolymer and fire retardant materials can be added to the reaction mixture to produce fire retardant foams. The foams have improved physical properties and flammability resistance.