Process for preparing a flexible polyurethane foam
View Patent ↗Process for preparing flexible polyurethane foam by reacting an MDI-based polyisocyanate terminated prepolymer and a polyether polyol with a high oxyethylene content and foams produced by such process.
1. A process for preparing a flexible polyurethane foam comprising reacting:
(a) a polyisocyanate-terminated prepolymer consisting of the reaction product of:
(i) 80-100% by weight of a diphenylmethane diisocyanate comprising at least 40% by weight of 4,4′-diphenylmethane diisocyanate and/or a derivative of said diphenylmethane diisocyanate that is liquid at 25° C.,
(ii) 20-0% by weight of another polyisocyanate,
(iii) a first polyether polyol having an average nominal functionality of 2-8, an average equivalent weight of 750-5000, an average molecular weight of 2000-12000, and an oxyethylene content of 50-90% by weight, and
(iv) a second polyether polyol having an average nominal hydroxyl functionality of 2-8, an average equivalent weight of 750-5000, an average molecular weight of 2000-12000, and an oxyethylene content of 0-25% by weight,
wherein, the first polyether polyol and the second polyether polyol are used in a weight ratio of from 30:70 to 70:30 and
(b) an isocyanate-reactive composition consisting of:
(i) 80-100% by weight of a polyether polyol having an average nominal functionality of 2-8, an average equivalent weight of 750-5000, an average molecular weight of 2000-12000, and an oxyethylene content of 50-90% by weight, and
(ii) 20-0% by weight of one or more other isocyanate-reactive compounds other than water; in the presence of water, wherein the reaction is conducted at an isocyanate index of 70 to 120 and the polyisocyanate-terminated prepolymer has a NCO value of 5-30% by weight.
2. The process according to claim 1 , wherein the polyisocyanate-terminated prepolymer prepolymer has a NCO value of 10-25% by weight and the diphenylmethane diisocyanate comprises at least 70% by weight of 4,4′-diphenylmethane diisocyanate and/or a derivative of said diphenylmethane diisocyanate that is liquid at 25° C.
3. The process of claim 2 , wherein the first polyether polyol has an average nominal functionality of 2-6, an average equivalent weight of 1000-4000, an average molecular weight of 2000-10000, and an oxyethylene content of 60-85% by weight.
4. The process of claim 2 , wherein the second polyether polyol has an average nominal hydroxyl functionality of 2-6, an average equivalent weight of 1000-4000, an average molecular weight of 2000-10000, and an oxyethylene content of 5-20% by weight.
5. The process of claim 3 , wherein the second polyether polyol has an average nominal hydroxyl functionality of 2-6, an average equivalent weight of 1000-4000, an average molecular weight of 2000-10000, and an oxyethylene content of 5-20% by weight.
6. The process of claim 2 , wherein the polyether polyol (b)(i) has an average nominal functionality of 2-6, an average equivalent weight of 1000-4000, an average molecular weight of 2000-10000, and an oxyethylene content of 60-85% by weight.
7. The process of claim 5 , wherein the polyether polyol (b)(i) has an average nominal functionality of 2-6, an average equivalent weight of 1000-4000, an average molecular weight of 2000-10000, and an oxyethylene content of 60-85% by weight.
8. A flexible polyurethane foam obtained according to the process of claim 1 .
9. A flexible polyurethane foam obtained according to the process of claim 7 .