Low energy-loss, high firmness, temperature sensitive polyurethane foams
AssigneeFoamex L.P.
InventorsDaniel V. Tursi, Jr., Chiu Y. Chan, Beat Niederoest
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Abstract
Foaming a polyurethane foam at above atmospheric pressure conditions using a mixture of polyisocyanate and a specific mixture of low molecular weight (high OH number) polyether and graft polyols produces viscoelastic foams with high firmness, low energy losses and high temperature sensitivity such that firmness is reduced by at least 25% when the foam is heated from room temperature (e.g., about 70° F. (21° C.)) to 100° F. (38° C.). The foam-forming ingredients are mixed together and foamed at controlled pressures in the range 1.05 to 1.5 bar (absolute), preferably 1.1 to 1.3 bar (absolute).
Claims13
A method for producing a viscoelastic polyurethane foam, comprising:
- (1) preparing a reaction mixture comprising:
- (a) a polyol mixture of (i) about 30 to 95 percent by weight total polyols of a polyether polyol, and having a hydroxyl number in the range of about 180 to 280 and a functionality from 2.7 to 3.3, and (ii) about 5 to 70 percent by weight total polyols of a graft polyol having a hydroxyl number in the range of about 25 to 50 and a functionality from 2.5 to 3.0;
- (b) an organic polyisocyanate selected from the group consisting of toluene diisocyanate and methylene diisocyanate mixed with toluene diisocyanate, wherein at least 50 percent of the methylene diisocyanate is 4, 4′ methylene diisocyanate, wherein if a mixture of methylene diisocyanate and toluene diisocyanate is used, the polyisocyanate mixture comprises from about 5 to 20 percent by weight toluene diisocyanate and about 80 to 95 percent by weight methylene diisocyanate, and wherein the isocyanate index is below about 120;
- and
- (c) from about 1.5 to 3.0 parts per hundred parts polyol of water as a blowing agent;
- and
- (2) allowing said reaction mixture to react while held at a pressure of about 1.05 to 1.5 bar (absolute) so as to form the viscoelastic polyurethane foam, wherein the viscoelastic polyurethane foam at room temperature has a density of at least 2.0 pounds per cubic foot, a ball rebound of at least 9%, and an IFD25 in the range of about 20 to 60 lbf, and wherein the viscoelastic foam has a temperature sensitivity such that when the foam is heated from room temperature to about 100° F. (38° C.) the IFD25 is reduced by 25% or more from the room temperature IFD25 value.
Dependencies are inferred from the claim text.