Methods for preparing open-celled polyurethane foams, systems for use therein, and open-celled polyurethane foams produced thereby
View Patent ↗Disclosed are methods and systems for preparing open-celled polyurethane foams by a discontinuous box foam process in which (a) a polyurethane foam-forming composition is deposited into a container having a gas-permeable base and (b) the polyurethane-foam forming composition is allowed to form an open-celled polyurethane foam in the container. In these methods and systems, the gas-permeable base is heated before, during, and/or after step (a) and heating is continued during at least a portion of step (b).
1. A method for preparing an open-celled polyurethane foam, comprising:
(a) depositing a polyurethane foam-forming composition comprising a polyisocyanate component and a polyol component into a container having a gas-permeable base, wherein the polyol component comprises:
(i) 20 to 40% by weight, based on the total weight of the polyol component, of a polypropylene oxide-based polyether diol having an OH number in the range of from 450 to 600;
(ii) 30 to 50% by weight, based on the total weight of the polyol component, of a poly(propylene/ethylene oxide) glycerin-initiated polyether triol having an OH number in the range of from 26 to 34; and
(iii) 10 to 30% by weight, based on the total weight of the polyol component, of a polypropylene oxide-based polyether triol having an OH number in the range of from 400 to 550; and
(b) allowing the polyurethane-foam forming composition to form an open-celled polyurethane foam in the container,
wherein the method comprises heating the gas-permeable base, with a heating device comprising a heating pad, matt or plate disposed beneath the gas-permeable base, before, during, and/or after step (a) and continuing the heating during at least a portion of step (b), and
wherein the method is discontinuous.
2. The method of claim 1 , wherein the container is a box formed by a base and at least 4 side walls, and, optionally a cover or lid.
3. The method of claim 1 , wherein the gas-permeable base is constructed of cardboard and/or paper.
4. The method of claim 1 , wherein the polyisocyanate component comprises a mixture of a diphenyl methane diisocyanate and a polyphenyl polymethylene polyisocyanate in which from 10 to 50% h weight of the total polyisocyanate is a diphenyl methane diisocyanate and from 50 to 90% of the total polyisocyanate is a polyphenyl polymethylene polyisocyanate, is used.
5. The method of claim 1 , wherein the base is heated to a temperature of at least 30° C. and up to 120° C.
6. The method of claim 5 , wherein the base is heated to a temperature of at least 35° C. and up to 70° C.
7. The method of claim 1 , wherein the base is heated to a temperature of at least 10° C. higher than the temperature of the ambient air in which the container is disposed.
8. The method of claim 2 , wherein the base is heated to a temperature of at least 10° C. higher than the temperature of the side walls of the container.
9. The method of claim 5 , wherein (b) comprises continuing the heating and maintaining the temperature of the base at a temperature of at least 30° C. and up to 120° C. during the entire period from the beginning, of the emergence of a first amount of the foam-forming composition from a mixing head through a degas process.
10. The method of claim 8 , wherein the base is heated to a temperature at least 20° C. higher than the temperature of the side walls of the container.
11. A method for preparing an open-celled polyurethane foam, comprising:
(a) depositing a polyurethane foam-forming composition comprising a polyisocyanate component and a polyol component into a container having a gas-permeable base, wherein the polyol component comprises:
(i) 20 to 40% by weight, based on the total weight of the polyol component, of a polypropylene oxide-based polyether diol having an OH number in the range of from 450 to 600;
(ii) 30 to 50% by weight, based on the total weight of the polyol component, of a poly(propylene/ethylene oxide) glycerin-initiated polyether triol having an OH number in the range of from 26 to 34; and
(iii) 10 to 30% by weight, based on the total weight of the polyol component, of a polypropylene oxide-based polyether triol having an OH number in the range of from 400 to 550; and
(b) allowing the polyurethane-foam forming composition to form an open-celled polyurethane foam in the container,
wherein only the gas-permeable base and optionally a bottom portion of the side wails of the container are heated before, during, and/or after step (a) and continuing the heating during at least a portion of step (b), and
wherein the method is discontinuous.
12. The method of claim 11 , wherein up to 10% of the length of the side walls, proximate to the base, are heated.
13. The method of claim 11 , wherein the polyisocyanate component comprises a mixture of a diphenyl methane diisocyanate and a polyphenyl polymethylene polyisocyanate in which from 10 to 50% by weight of the total polyisocyanate is a diphenyl methane diisocyanate and from 50 to 90% of the total poiviaocyanate is a polyphenyl polymethylene polyisocyanate, is used.
14. The method of claim 11 , wherein only the base and optionally a bottom portion of the side walls of the container are heated to a temperature of at least 30° C. and up to 120° C.
15. The method of claim 14 , wherein the base is heated to a temperature of at least 35° C. and up to 70° C.
16. The method of claim 11 , wherein the base is heated to a temperature of at least 10° C. higher than the temperature of the ambient air in which the container is disposed.
17. The method of claim 11 , wherein up to 10% of the length of the side walls, proximate to the base, are heated.
18. The method of claim 11 , wherein the gas-permeable base is heated with a heating device comprising a heating pad, malt or plate disposed beneath the gas-permeable base.