Claims
- 1. An isocyanate-terminated prepolymer having an NCO content of more than 31 to about 33.5% by weight comprising:
- (a) a polyphenylene polymethylene polyisocyanate comprising
- (i) about 30 to about 100% by weight of diphenylmethane diisocyanate and
- (ii) the remainder selected from the group consisting of higher homologues of polyphenylene polymethylene polyisocyanate, isocyanate-containing ester groups, urea groups, biuret groups, aliphatic groups, carbodiimide groups, isocyanurate groups, uretdione groups and urethane groups; and
- (b) a polyoxyalkylene polyol having an oxyethylene content of about 30 to about 90%, a molecular weight of about 1000 to about 12000 and a functionality of about 2 to about 8, wherein the weight ratio of component (a) to component (b) is from about 99.9:0.1 to about 97.5:2.5.
- 2. An isocyanate-terminated prepolymer as claimed in claim 1 wherein the weight ratio of component (a) to component (b) is from about 99.9:0.1 to about 97.5:2.5.
- 3. An isocyanate-terminated prepolymer as claimed in claim 1 wherein the weight ratio of component (a) to component (b) is from about 99.85:0.15 to about 99.0:1.0.
- 4. An isocyanate-terminated prepolymer as claimed in claim 1 wherein component (a) comprises from about 35 to about 100% diphenylmethane diisocyanate.
- 5. An isocyanate-terminated prepolymer as claimed in claim 4 wherein component (a) comprises from about 40 to about 100% diphenylmethane diisocyanate.
- 6. An isocyanate-terminated prepolymer as claimed in claim 1 wherein component (b) has an oxyethylene content of from about 30 to about 90% by weight.
- 7. An isocyanate-terminated prepolymer as claimed in claim 1 wherein component (b) has a functionality of from about 2 to about 6.
- 8. An isocyanate-terminated prepolymer as claimed in claim 1 wherein component (b) has a molecular weight of from about 1200 to about 10000.
- 9. A method of preparing an isocyanate-terminated prepolymer as claimed in claim 1 which method comprises reacting isocyanate component (a) directly with polyol component (b).
- 10. A method of preparing an isocyanate-terminated prepolymer as claimed in claim 1 which method comprises first reacting a portion of isocyanate component (a) with polyol component (b) to form a semi-prepolymer and then diluting the semi-prepolymer with the remainder of polyisocyanate component (a).
- 11. A polyurethane foam comprising the reaction product of an isocyanate-terminated prepolymer as claimed in claim 1 and an isocyanate reactive component.
- 12. A polyurethane foam as claimed in claim 11 having a density of less than about 2 pcf.
Parent Case Info
This application claims benefit of provisional application Ser. No. 60/040,292, filed Feb. 11, 1997.
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0022617 |
Jan 1981 |
EPX |
0 566 251 |
Oct 1993 |
EPX |