Claims
- 1. A process for the production of a rigid polyurethane foam comprising mixing
- a) an NCO-terminated prepolymer which is the reaction product of
- 1) a polymeric diphenylmethane diisocyanate having a viscosity at 25.degree. C. of from about 50 to about 1,000 mPa.multidot.s and
- 2) a polyester polyol blend having a functionality of from about 1.8 to about 4.0 and a molecular weight of from about 400 to about 2,000
- formed by reacting 1) and 2) in amounts such that the equivalent ratio of isocyanate groups to hydroxyl groups is from about 15:1 to about 160:1,
- b) a compound containing isocyanate-reactive hydrogen atoms, and
- c) a blowing agent selected from the group consisting of 1,1-dichloro-1-fluoroethane, 1,1,1,3,3-pentafluoropropane, n-pentane, cyclopentane, isopentane, and tetrafluoroethane and allowing the reaction mixture to form a foam.
- 2. The process of claim 1 in which polyol a)2) is a polyester polyol blend having a functionality of approximately 2.
- 3. The process of claim 2 in which the polyester polyol blend is a phthalic acid anhydride-based polyester polyol.
- 4. The process of claim 2 in which the compound containing isocyanate-reactive hydrogen atoms b) is selected from the group consisting of polyester blends based on phthalic anhydride and polyester blends based on 1,4- and 1,2-benzenedicarboxylic acid.
- 5. The process of claim 1 in which the blowing agent c) is HCFC 141b.
- 6. The process of claim 1 in which the reaction mixture is applied to a substrate.
Parent Case Info
This application is a Continuation-In-Part of application Ser. No. 08/961,403 filed Oct. 30, 1997, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4791148 |
Riley et al. |
Dec 1988 |
|
5362764 |
Londrigan et al. |
Nov 1994 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
961403 |
Oct 1997 |
|