Patent ID: 7459488

Claim:
A process for removing hydrocarbon material from wanted material comprising the steps of: obtaining a prepolymer, said prepolymer having an NCO value of 2-10% by weight and being the reaction product obtained by reacting an excessive amount of polymethylene polyphenylene polyisocyanate comprising at least 25% by weight of 4,4′-diphenylmethane diisocyanate or a liquid variant thereof with a polyether polyol having an average nominal hydroxyl functionality of from 2 to 4, a number average hydroxyl equivalent weight of from 500 to 3000, and an oxyethylene content of at least 50% by weight, blending a compressed gas with said prepolymer to create a modified prepolymer, said compressed gas being a propellant, mixing said modified prepolymer with water in a static mixer, characterized in that the modified prepolymer is mixed with 1-100 parts by weight of the water per part weight of the modified prepolymer, said compressed gas providing necessary turbulence in said static mixer to achieve a satisfactory mix, bringing the mixed modified prepolymer and water composition into contact with the materials within 10 seconds of mixing; allowing the prepolymer to react with at least part of the water to form a flexible foam; and removing the foam obtained from the wanted material.