Appeal 2007-1905
Reissue Application 10/931,249
Patent 6,444,720 B1
1 Background of the invention
2 Rigid polyurethane foams are generally prepared from (1) polyols
3 having on average at least three hydroxyl groups per molecule,
4 (2) difunctional isocyanates, (3) catalysts, (4) stabilizers, (5) blowing agents,
5 and (6) other conventional additives. Specification, col. 1:9-13.
6 The polyol component can be a polyether polyol having on average at
7 least three hydroxyl groups with a hydroxyl value of from 100 to 900.
8 Specification, col. 1:14-18.
9 Blowing agents include volatile organic compounds or water.
10 Specification, col. 1:19-20.
11 Water functions as a blowing agent by reacting with the isocyanate to
12 form carbon dioxide. Specification, col. 1:21-23.
13 According to Bayer, a resultant rigid polyurethane foam is "mostly
14 predominantly closed-cell foams." Specification, col. 1:24-25.
15 In order to obtain open-cell foams, "polyols with a high content of
16 oxyethylene groups and/or special silicone stabilisers [sic--stabilizers] and/or
17 additives such as calcium stearate, solids, or oleochemical derivatives are
18 used." Specification, col. 1:25-29.
19 According to Bayer, Okada describes the preparation of open-
20 cell rigid polyurethane foams using polyether polyols. Specification,
21 col. 1:45-53.
22
23 The invention
24 Bayer's invention is said to provide predominantly open-cell rigid
25 polyurethane foams. Specification, col. 1:65-66.
4
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Next
Last modified: September 9, 2013