Polyurethane foam composition

Abstract

Single component compositions for making a moisture-cured polyurethane foam are disclosed. Foam produced from the compositions of the present invention produce very low foaming pressure due to their 60-95 percent open-cell content. After these compositions are applied and cure, they form a permanent seal around the perimeter of installed fenestration products.

1 . A single component foam forming composition comprising a mixture of 
 (a) prepolymers containing free isocyanate groups in the range of 12 to 17 percent by weight, based on the prepolymer, which is produced by reacting a polyisocyante with a polyol blend comprising a first polyol that is a triol having a molecular weight from 500 to 3000 and a second polyol is a diol, triol or a mixture thereof having a molecular weight of from 4,000 to 12,000 wherein the first to second polyol are present in a parts by weight ratio of form 1:6 to 1:2; and    (b) a blowing agent.    
     
     
         2 . The composition of  claim 1  further comprising from 0.5 to 4 percent by weight, based on the total weight of the composition, of a polydimethyl siloxane polyoxyalkylene copolymer surfactant.  
     
     
         3 . The composition of  claim 2  wherein the surfactant comprises 1 to 3 percent by weight of the composition.  
     
     
         4 . The composition of  claim 2  wherein the surfactant has a molecular weight of less than 30,000.  
     
     
         5 . (canceled)  
     
     
         6 . The composition according to  claim 1 , wherein the polyisocyanate is selected from the group consisting of aliphatic, cycloaliphatic, aryliphatic, and aromatic polyisocyanates.  
     
     
         7 . The composition according to  claim 6 , wherein the polyisocyanate is an aromatic polyisocyanate selected from a diphenylmethane diisocyanate, polyphenyl polymethylene isocyanate or a combination thereof.  
     
     
         8 . The composition of  claim 1  wherein the blowing agent is a hydrocarbon, a fluorocarbon, a chlorocarbon, a chlorofluorocarbon or a mixture thereof.  
     
     
         9 . The composition of  claim 8  wherein the blowing agent is a hydrocarbon selected from isobutane, propane, dimethylether or a mixtures thereof.  
     
     
         10 . The composition of  claim 1  wherein the composition contains additional auxiliary agent selected from amine catalysts, tin catalysts or flame retardants.  
     
     
         11 . The composition of  claim 1 , wherein the triols and diols together comprise a secondary hydroxyl functionality of at least about 50 percent.  
     
     
         12 . The composition of  claim 5  wherein the second polyol is a diol.  
     
     
         13 . The composition of  claim 5  wherein the second polyol is a triol.  
     
     
         14 . A moisture-cured polyurethane foam prepared from a composition of  claim 1 .  
     
     
         15 . A foam of  claim 14  wherein the foam has an open cell structure of from 60 to 95 percent open cells.  
     
     
         16 . A method for the production of a polyurethane foam comprising supplying to a valved vessel a mixture comprising an isocyanate-terminated prepolymer and a blowing agent wherein the prepolymer is obtained by reacting a polyisocyanate with a polyol mixture comprising a first polyol that is a triol having a molecular weight from 500 to 3000, and a second polyol that is a diol, triol or mixture thereof having a molecular weight from 4000 to 12,000, wherein the first and second polyols are present in a parts by weight ratio of from 1:6 to 1:2, allowing the mixture to reach equilibrium, adding pressure if needed, maintaining the pressure during storage and releasing the mixture outside the vessel to produce a foam which as a cell structure of from 60 to 95 percent open cells.  
     
     
         17 . The method of  claim 16  wherein the mixture is dispensed from the vessel using a gun-like dispenser with or without a straw extender tip or with a trigger-straw dispenser.