Foam composite

Abstract

A foam composite made up of a scaffold of an open cell hydrophobic material having plurality of surfaces defining a plurality of pores, and a coating of a substantially hydrophilic foam material disposed upon the surfaces of the hydrophobic foam. The resulting foam composite exhibits structural characteristics of the hydrophobic foam and absorbency characteristics of the hydrophilic foam.

What is claimed is:  
     
         1 . A foam composite comprising: 
 a scaffold of an open cell hydrophobic polyurethane foam, said scaffold having a plurality of surfaces defining a plurality of pores; and    a coating of a substantially open cell hydrophilic polyurethane foam disposed upon said plurality of surfaces of said hydrophobic polyurethane foam;    wherein said foam composite exhibits structural characteristics of said hydrophobic polyurethane foam and absorbency characteristics of said open cell hydrophilic polyurethane foam.    
     
     
         2 . The foam composite of  claim 1 , wherein said coating is from about 1% to about 90% by weight of said foam composite.  
     
     
         3 . The foam composite of  claim 1 , wherein said coating is the in situ reaction product of a hydrophilic polyurethane prepolymer emulsion having a prepolymer phase and an aqueous phase.  
     
     
         4 . The foam composite of  claim 3 , wherein the ratio of said aqueous phase to said prepolymer phase is from about 0.8:1 to about 2.2:1.  
     
     
         5 . The foam composite of  claim 1 , wherein said coating is prepared by the in situ deposition of a hydrophilic polyurethane prepolymer from a solution of said polymer in a nonreactive solvent.  
     
     
         6 . The foam composite of  claim 5 , wherein said hydrophilic polyurethane prepolymer solution is from about 1% by weight to about 60% by weight prepolymer.  
     
     
         7 . The foam composite of  claim 5 , wherein said nonreactive solvent is selected from the group comprising acetone, toluene, xylene, benzene or mixtures thereof.  
     
     
         8 . The foam composite of  claim 1 , wherein said open cell hydrophilic polyurethane foam comprises the polymerization products of an isocyanate-capped polyether prepolymer having an isocyanate functionality from about 5% by weight to about 15% by weight of said prepolymer.  
     
     
         9 . The foam composite of  claim 8 , wherein said isocyanate-capped polyether prepolymer has an isocyanate functionality from about 6% by weight to about 9% by weight of said prepolymer.  
     
     
         10 . The foam composite of  claim 1 , wherein said foam composite has a pore size distribution from about 4 pores per linear inch to about 100 pores per linear inch.  
     
     
         11 . The foam composite of  claim 1 , wherein said foam composite has a void volume from about 20% to about 98%.  
     
     
         12 . The foam composite of  claim 1 , wherein said foam composite has a surface area from about 100 ft 2  per cube foot to about 2,000 ft 2  per cubic foot of foam composite.  
     
     
         13 . The foam composite of  claim 12 , wherein said foam composite has a surface area of from about 300 ft 2  per cubic foot to about 2000 ft 2  per cubic foot of foam composite and a pore size distribution in the range from about 10 pore/linear inch to about 95 pore/linear inch.  
     
     
         14 . The foam composite of  claim 1 , wherein said foam composite has a rate of absorbency for water at 20° C. from about 0.1 seconds to about 60 seconds.  
     
     
         15 . The foam composite of  claim 1 , wherein said foam composite has a pressure drop of about 0.14 inches of water to about 2.7 inches water for 575 ft/minute of dry air through a foam composite having a surface area of 1 ft 2 , a thickness of 1 inch and a pore size in the range from about 10 pore/linear inch to about 90 pore/linear inch.  
     
     
         16 . The foam composite of  claim 1 , wherein said foam composite has a pressure drop rate of from about 0.1 psi to about 2 psi for about 2 gallons of water at 39° F. through about 2 in 2  of foam composite having a thickness of 7 inches for foam composites having a weight ratio of hydrophilic polyurethane foam to hydrophobic polyurethane foam in the range of from about 0.1 to 1 to about 4.0 to 1 over a pore size distribution range from about 10 pore/linear inch to about 45 pore/linear inch.  
     
     
         17 . The foam composite of  claim 16 , wherein said foam composite has a pore size distribution in the range 10 pores per linear inch to 100 pores per linear inch.  
     
     
         18 . The foam composite of  claim 1 , wherein said coating of hydrophilic polyurethane foam has a coating weight from about 0.5 grams hydrophilic foam/gram hydrophobic foam to about 10 grams hydrophilic foam/gram hydrophobic foam.  
     
     
         19 . The foam composite of  claim 1 , wherein said foam composite has a tensile strength from about 10 psi to 35 psi over a pore size distribution range from about 10 ppi to about 90 ppi.  
     
     
         20 . The foam composite of  claim 1 , wherein said foam composite has an elongation characteristic from about 150% to about 260% by weight over a pore size distribution range from about 10 ppi to about 100 ppi.  
     
     
         21 . The foam composite of  claim 1 , wherein said hydrophilic polyurethane coating further comprises an additive.  
     
     
         22 . The foam composite of  claim 21 , wherein said additive is a non-bioactive ingredient.  
     
     
         23 . The foam composite of  claim 22 , wherein said non-bioactive ingredient comprises a hydrogel, a filler, an activated charcoal, a zeolite, an ion exchange resin, a phase change material or mixtures thereof.  
     
     
         24 . The foam composite of  claim 23 , wherein said hydrogel is a polysaccharide hydrogel or an acrylic hydrogel.  
     
     
         25 . The foam composite of  claim 24 , wherein said polysaccharide hydrogel is an alginate, a carrageenan, an agar, an agarose, a curdlan, a pullulan, a gellan or mixtures thereof.  
     
     
         26 . The foam composite of  claim 24 , wherein said hydrogel is in an amount from about 0.1% to about 90% by weight of said hydrophilic polyurethane coating.  
     
     
         27 . The foam composite of  claim 24 , wherein said acrylic hydrogel is a polyacrylamide, a poly(ethyl methacrylate), a poly(glycol methacrylate), a poly(hyroxy methyl acrytate), a poly(sodium acrylate) or mixtures thereof.  
     
     
         28 . The foam composite of  claim 22  wherein said bioaffecting agent comprises a pharmaceutical, a fragrance, a soap, a herbicide, a pesticide, a yeast, a bacterium, a algae, an enzyme, a plant, an animal cell, a human cell, or mixtures thereof.  
     
     
         29 . The foam composite of  claim 1 , further comprising an non-bioactive ingredient or a bioaffecting agent.  
     
     
         30 . The foam composite of  claim 29 , wherein said non-bioactive ingredient or said bioaffecting agent is immobilized within said foam composite.  
     
     
         31 . The foam composite of  claim 30 , wherein said non-bioactive ingredient comprises a hydrogel, a filler, an activated charcoal, a zeolite, an ion exchange resin, a phase change material or mixtures thereof.  
     
     
         32 . The foam composite of  claim 30 , wherein said bioaffecting agent comprises a pharmaceutical, a fragrance, a soap, a yeast, a herbicide, a pesticide, an enzyme, a bacterium, a algae, a plant, an animal cell, a human cell or mixtures thereof.  
     
     
         33 . The foam composite of  claim 29 , wherein said bioaffecting agent is grafted onto said non-bioactive ingredient.  
     
     
         34 . The foam composite of  claim 33 , wherein said non-bioactive ingredient is a hydrogel.  
     
     
         35 . A process of making a foam composite which comprises: 
 (a) preparing an emulsion of a hydrophilic polyurethane prepolymer which upon curing forms a substantially open cell hydrophilic polyurethane polymer foam;    (b) contacting an open cell hydrophobic polyurethane foam having a plurality of surfaces defining a plurality of pores with said hydrophilic polyurethane prepolymer emulsion;    (c) curing said hydrophilic polyurethane prepolymer emulsion while in contact with said hydrophobic polyurethane for a period of time sufficient to form a coating of said substantially open cell hydrophilic polyurethane polymer foam on hydrophobic polyurethane foam without closing the pores of said hydrophobic polyurethane foam.    
     
     
         36 . The process of  claim 35 , wherein said contacting is accomplished by dipping said reticulated hydrophobic foam into said polyurethane prepolymer emulsion.  
     
     
         37 . The process of  claim 35 , wherein said contacting is a mechanical extrusion of said polyurethane prepolymer emulsion onto the surface of said reticulated hydrophobic polyurethane substantially uniformly and allowing said emulsion to permeate into said reticulated hydrophobic polyurethane.  
     
     
         38 . The process of  claim 37 , wherein said mechanical extrusion is performed with nip rollers or doctor blades.  
     
     
         39 . The process of  claim 35 , further comprising blowing air through said emulsion coated reticulated polyurethane foam prior to said curing step.  
     
     
         40 . The process of  claim 35 , wherein said prepolymer emulsion further comprises an additive selected from the group consisting of non-bioactive ingredients or bioaffecting agents.  
     
     
         41 . The process of  claim 40 , wherein said non-bioactive ingredient comprises a hydrogel, a filler, an activated charcoal, a zeolite, an ion exchange resin, a phase change material or mixtures thereof.  
     
     
         42 . The process of  claim 40 , wherein said bioaffecting agent comprises a pharmaceutical, a fragrance, a soap, a herbicide, a pesticide, a yeast, a bacterium, an algae, an enzyme, a plant, an animal cell, a human cell or mixtures thereof.  
     
     
         43 . A process of making a foam composite which comprises: 
 (a) preparing a solution of a hydrophilic polyurethane prepolymer which upon curing forms a substantially open cell hydrophilic polyurethane polymer foam and a solvent therefor;    (b) contacting an open cell hydrophobic polyurethane foam having a plurality of surfaces defining a plurality of pores with said polyurethane prepolymer solution;    (c) recovering said solvent from said polyurethane prepolymer solution in step (b) and leaving a coating of said hydrophilic polyurethane prepolymer on said open cell hydrophobic polyurethane foam; and    (d) curing said polyurethane prepolymer for a period of time sufficient to form a coating of said substantially open cell hydrophilic polyurethane polymer foam on said hydrophobic polyurethane foam without closing the pores of said hydrophobic polyurethane foam.    
     
     
         44 . The process of  claim 43 , wherein said solution of step (a) contains from about 20 wt % to about 80 wt % prepolymer in a solvent which is non-reactive with said prepolymer while steps (a) through (c) are performed.  
     
     
         45 . The process of  claim 44 , wherein said non-reactive solvent is acetone, toluene, benzene, xylene or mixtures thereof.  
     
     
         46 . The process of  claim 45 , wherein said curing step is immersion curing in a water bath at a temperature in the range of from about 4° C. to about 50° C., or water vapor curing in a gas stream at a temperature in the range of from about 30° C. to about 100° C. and having a relative humidity of about 85% to about 100%.  
     
     
         47 . The process of  claim 43 , further comprising removing excess solvent from said prepolymer solution contacted hydrophobic polyurethane foam after step.  
     
     
         48 . The process of  claim 43 , further comprising blowing air through said prepolymer solution coated hydrophobic polyurethane foam prior to step (c).  
     
     
         49 . A process of making a foam composite which comprises: 
 (a) preparing a liquid phase of a hydrophilic polyurethane prepolymer which upon curing forms a substantially open cell hydrophilic polyurethane foam at from about 25° C. to about 40° C.;    (b) contacting an open cell hydrophobic polyurethane foam having a plurality of surfaces defining a plurality of pores with said liquid phase of a hydrophilic polyurethane prepolymer;    (c) curing said polyurethane prepolymer for a period of time sufficient to form a coating of said substantially open cell hydrophilic polyurethane polymer foam on said hydrophobic polyurethane foam without closing the pores of said hydrophobic polyurethane foam.    
     
     
         50 . A process of making a foam composite which comprises: 
 (a) preparing a scaffold of an open cell hydrophobic polyurethane foam, said scaffold having a plurality of surfaces defining a plurality of pores;    (b) preparing a hydrophilic polyurethane prepolymer emulsion which upon curing forms a substantially open cell hydrophilic polyurethane foam;    (c) preparing a hydrogel emulsion;    (d) mixing said prepolymer emulsion with said hydrogel emulsion to obtain a composite emulsion;    (e) contacting said scaffold of an open cell hydrophobic polyurethane foam with said composite emulsion; and    (f) curing said composite emulsion while in contact with said reticulated hydrophobic polyurethane to form a coating of said substantially open cell hydrophilic polyurethane polymer foam on said hydrophobic polyurethane foam scaffold without closing the pores of said hydrophobic polyurethane foam.    
     
     
         51 . The process of claim  50 , wherein said composite emulsion contains from about 1% to about 70% by weight hydrogel.  
     
     
         52 . A foam composite as recited in  claim 1  wherein said open cell hydrophobic polyurethane foam scaffold is reticulated.  
     
     
         53 . A foam composite as recited in claim  52  wherein said foam scaffold is highly reticulated.