Catalyst system and method for preparing flame resistant materials

Abstract

Presently, multifunctional carboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA) are used to bond a hydroxyl-functional organophosphorous oligomer to cotton fabric in the presence of a catalyst, such as sodium hypophosphite (NaH 2 PO 2 ). However, the free carboxylic acid groups bound to the cotton fabric form a calcium salt during home laundering, thus diminishing the flame retardant properties of the treated cotton fabric. Disclosed herein is a new catalyst system consisting of hypophosphorous acid (H 3 PO 2 ) and a nitrogen-containing organic base such as triethanol amine (TEA). When the catalyst system is present together with the polycarboxylic acid, TEA esterifies the free carboxylic acid groups under curing conditions, thus reducing calcium concentration on the fabric during home laundering. It also provides nitrogen-phosphorous synergism to enhance the flame retardant performance of the organophosphorous compound. The cotton fabric treated with BTCA and the hydroxyl-functional organophosphorous oligomer in the presence of this new catalyst system demonstrate flame retardant properties superior to that treated with NaH 2 PO 2 as a catalyst.

I claim:  
     
         1 . A method of binding a flame retardant compound or composition to cellulose comprising: 
 applying a composition comprising a hydroxyalkyl-functionalized flame retardant, a polycarboxylic acid, hypophosphorous acid and a nitrogen-containing organic base to a cellulose-containing material.    
     
     
         2 . The method of  claim 1 , further comprising curing the cellulose-containing material at a temperature of between 200 to 100° C. for a time of between 20 seconds and 10 minutes.  
     
     
         3 . The method of  claim 1 , wherein said flame retardant is a hydroxylalkyl-functionalized organophosphorous compound.  
     
     
         4 . The method of  claim 3 , wherein said hydroxylalkyl-functionalized organophosphorous compound is Fyrol  51 .  
     
     
         5 . The method of  claim 1 , wherein said polycarboxylic acid is 1,2,3,4-butanetetracarboxylic acid.  
     
     
         6 . The method of  claim 1 , wherein said nitrogen-containing organic base is TEA.  
     
     
         7 . The method of  claim 1 , wherein said nitrogen-containing organic base is hydroxylalkyl functionalized.  
     
     
         8 . The method of  claim 1 , wherein said flame-retardant is present in the composition at 2 to 40 weight percent.  
     
     
         9 . The method of  claim 1 , wherein said polycarboxylic acid is present in the composition at 1 to 20 weight percent.  
     
     
         10 . The method of  claim 1 , wherein said hypophosphorous acid is present in the composition at 1 to 12 weight percent.  
     
     
         11 . The method of  claim 1 , wherein said nitrogen-containing organic base is present in the composition at a weight percent which maximizes the esterification of cellulose-containing material.  
     
     
         12 . The method of  claim 11 , wherein said nitrogen-containing organic base is present in the composition at 1 to 15 weight percent.  
     
     
         13 . The method of  claim 1 , further comprising adjusting the pH to between 2 to 4.5.  
     
     
         14 . A catalyst system for applying flame retardants to fabric comprising hypophosphorous acid and a nitrogen containing organic base.  
     
     
         15 . The catalyst system of  claim 14 , wherein said nitrogen containing organic base is triethanolamine.  
     
     
         16 . The catalyst system of  claim 14 , wherein said nitrogen containing organic base is selected from the group consisting of: triethanolamine, diethanolamine, and ethanolamine.