Claims
- 1. A method for producing a rigid polyurethane foam, which comprises mixing (a) a polyisocyanate component with a polyol component comprising (b) a polyol mixture, (c) a catalyst, (d) a blowing agent and, if necessary, a flame retardant and a surfactant, then foaming the mixture;
- wherein the polyisocyanate component (a) is polymethylenepolyphenyl polyisocyanate or a modified material thereof;
- the polyol mixture (b) comprises:
- (b-1) 40 to 90 parts by weight based on 100 parts by weight of the polyol mixture (b), of an aromatic polyester polyol having a hydroxyl value of 170 to 350 mg KOH/g;
- (b-2) 10 to 50 parts by weight based on 100 parts by weight of the polyol mixture (b), of at least one aromatic polyether polyol having a hydroxyl value of 170 to 600 mg KOH/g, which is produced by using an aromatic amine, a Mannich base having an aromatic ring or a polyfunctional phenol as a starting material; and
- (b-3) not more than 30 parts by weight based on 100 parts by weight of the polyol mixture (b), of an alkanolamine having no aromatic ring and/or a polyether polyol having no aromatic ring, and a hydroxyl value of the polyol mixture (b) is from 170 to 400 mg KOH/g;
- the catalyst (c) is at least one metallic catalyst, which is optionally used in combination with a tertiary amine compound; and
- the blowing agent (d) is an adduct of a primary or secondary amine compound with carbon dioxide, which is optionally used in combination with a low-boiling point compound and/or water.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9-008410 |
Jan 1997 |
JPX |
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Parent Case Info
This is a divisional application of U.S. Ser. No. 09/007,014, filed Jan. 14, 1998.
US Referenced Citations (6)
Number |
Name |
Date |
Kind |
4077920 |
Yukuta et al. |
Mar 1978 |
|
4735970 |
Sommerfeld et al. |
Apr 1988 |
|
5026737 |
Ohnuma et al. |
Jun 1991 |
|
5648019 |
White, III et al. |
Jul 1997 |
|
5677359 |
White, III et al. |
Oct 1997 |
|
5684057 |
White, III et al. |
Nov 1997 |
|
Divisions (1)
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Number |
Date |
Country |
Parent |
07014 |
Jan 1998 |
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