Sugar-based polyurethanes, methods for their preparation, and methods of use thereof
View Patent ↗Polyurethane foams which are highly flame resistant are described, as well as the production of such polyurethane foams by the reaction between a natural polyol, such as sucrose or a blend of mono- or disaccharides in place of the standard hydrocarbon-based polyol component, a polyisocyanate and water in the presence of a suitable polyurethane forming catalyst and a flame retardant, and optionally one or more components such as surfactants and/or emulsifiers. The resultant polyurethane foam has a bio-based solid content ranging from about 17% to 30%, may be formulated in a variety of foam densities for a variety of applications, and exhibits a high degree of fire and burn resistance, as exhibited by the flame spread index and the smoke spread values.
1. A flame-retardant polyurethane foam comprising the reaction product of:
a first reaction mixture consisting of polyisocyanate and optionally a surfactant; and
a second reaction mixture consisting of:
a natural polyol wherein substantially all of the hydroxyl groups on the polyol are free;
a surfactant;
an aqueous blowing agent;
a polyurethane producing catalyst;
a flame-retardant; and
optionally, any one or any combination of a plasticizer, an emulsifier, a bacteriostat, a non-halogen containing blowing agent other than water, a filler, a dye or colorant, glycerine, a cross linker, an antioxidant, an antistatic agent, and/or a cell-opening agent;
wherein the first reaction mixture and the second reaction mixture are used in amounts to provide an Isocyanate Index of 20 to 50; and
wherein the flame-retardant polyurethane foam has a density of about 0.5 lb/ft 3 and meets the Conditions of Acceptance X2.1.6 according to ICC-ES AC 377 flammability tests.
2. The flame-retardant polyurethane foam according to claim 1 , wherein the natural polyol is selected from the group consisting of sucrose, fructose, glucose, xylose, corn syrup, dextrose, and molasses.
3. The flame-retardant polyurethane foam according to claim 1 , wherein the second reaction mixture comprises the emulsifier.
4. The flame-retardant polyurethane foam according to claim 1 , wherein the second reaction mixture is substantially hydrocarbon free.
5. A method of making a flame-retardant polyurethane foam, the method comprising:
a. admixing a first composition consisting of an untreated natural polyol in which substantially all of the hydroxyl groups are free, a surfactant, a polyurethane forming catalyst, a flame retardant, and water to form the first composition, wherein optionally, the first composition further contains any one of or any combination of a plasticizer, an emulsifier, a bacteriostat, a non-halogen containing blowing agent other than water, a filler, a dye or colorant, glycerine, a cross linker, an antioxidant, an antistatic agent, and/or a cell-opening agent, wherein water and, when present, the non-halogen containing blowing agent are present in amounts sufficient to provide a foam density of about 0.5 lb/ft 3 ;
b. contacting the first composition with a second composition consisting of a polyisocyanate and optionally a surfactant to form a reaction mixture; and
c. allowing the reaction mixture to foam,
the foam exhibiting a density of about 0.5 lb/ft 3 (8 Kg/m 3 ) and a flame spread value of 15 or less @ 4-inch foam thickness as determined by ASTM E-84;
wherein the first composition and the second composition are used in amounts to provide an Isocyanate Index of 20 to 50.
6. The method of claim 5 , wherein the first composition further contains the plasticizer.
7. The method of claim 5 , further comprising adding an emulsifier to the first composition.
8. A method for preparing a water-blown, low density, polyurethane foam, the method which comprises:
contacting a first reaction mixture consisting of at least one polyisocyanate and optionally a surfactant in an amount sufficient to provide an Isocyanate Index of 20 to 50 with a second reaction mixture consisting of at least one natural polyol, a surfactant, a flame retardant, a blowing agent composition consisting of at least 5 wt. % water and optionally a non-halogen containing blowing agent other than water, and an effective amount of a catalyst composition consisting of a gelling catalyst and a blowing catalyst for a period of time sufficient to produce a polyurethane foam, wherein the second reaction mixture optionally includes any one or any combination of a plasticizer, an emulsifier, a bacteriostat, a filler, a dye or colorant, glycerine, a cross linker, an antioxidant, an antistatic agent, and/or a cell-opening agent, wherein water and, when present, the non-halogen containing blowing agent are present in amounts sufficient to provide a foam density of about 0.5 lb/ft 3 ;
the foam exhibiting a density of about 0.5 lb/ft 3 (8 Kg/m 3 ) and a flame spread value of 15 or less @ 4-inch foam thickness as determined by ASTM E-84.
9. The method of claim 8 , wherein the at least one natural polyol is selected from the group consisting of sucrose in the form of a sucrose solution or an invert sucrose solution, corn syrup, dextrose, fructose, glucose, molasses, and combinations thereof.
10. The flame-retardant polyurethane foam according to claim 1 , wherein the flame-retardant polyurethane foam has a bio-based content ranging from about 15% to about 30% as determined by ASTM-D6866-11.
11. The flame-retardant polyurethane foam according to claim 1 , wherein the second reaction mixture comprises the plasticizer, wherein the plasticizer is selected from the group of phthalate plasticizers, phosphate or phosphorus-containing plasticizers, and benzoate plasticizers.
12. The method of claim 5 , wherein the polyurethane forming catalyst is present in an amount ranging from about 0.0001 wt. % to about 5 wt. %, inclusive, of the reaction mixture.
13. The flame-retardant polyurethane foam according to claim 1 , wherein the weight ratio of the second reaction mixture to the first reaction mixture is from about 0.75:1 to 2:1.
14. The flame-retardant polyurethane foam according to claim 1 , wherein the second reaction mixture comprises from about 5 wt. % to about 40 wt. % of flame retardant.
15. The flame-retardant polyurethane foam according to claim 1 , wherein the flame retardant is a phosphate compound.
16. The flame-retardant polyurethane foam according to claim 1 , wherein the flame retardant is selected from tris-(2-chloro-1-methylethyl)phosphate (TMCP), low-odor tris-(2-chloro-1-methylethyl)phosphate (TCPP-LO), tris-(chloroethyl)phosphate (TCEP), tris(chloroisopropyl)phosphate (TCPP), tri-cresyl phosphate (TCP), tris-(1,3-dichloro-2-propyl)phosphate (TDCP), low-viscosity tris-(1,3-dichloro-2-propyl)phosphate (TDCP-LV), and combinations thereof.
17. The flame-retardant polyurethane foam according to claim 1 , wherein the second reaction mixture comprises from 20 wt. % to about 70 wt. % of natural polyol.
18. The flame-retardant polyurethane foam according to claim 1 , wherein the volume ratio of the first reaction mixture to the second reaction mixture is between about 1.0 and 5.0.
19. The flame-retardant polyurethane foam according to claim 1 , wherein the volume ratio of the first reaction mixture to the second reaction mixture is about 1.0.
20. The flame-retardant polyurethane foam according to claim 1 , wherein the foam exhibits a flame spread value of 15 or less @ 4-inch foam thickness as determined by ASTM E-84.
21. The flame-retardant polyurethane foam according to claim 1 , wherein the foam exhibits a flame spread value of 5 or less @ 4-inch foam thickness as determined by ASTM E-84.
22. The flame-retardant polyurethane foam according to claim 1 , wherein the foam exhibits a percent modern carbon (pMC) value ranging from about 10% to about 50% as determined by ASTM-D6866-11.
23. The method of claim 5 , wherein the polyurethane forming catalyst is present in the first composition an amount from about 0.01 wt. % to about 10 wt. %.
24. The method of claim 5 , wherein the weight ratio of the first composition to the second composition is from about 0.75:1 to 2:1.
25. The method of claim 5 , wherein the foam exhibits a flame spread value of 5 or less @ 4-inch foam thickness as determined by ASTM E-84.
26. The method of claim 8 , wherein the foam exhibits a flame spread value of 5 or less @ 4-inch foam thickness as determined by ASTM E-84.