Method of Stabilizing Resorcinol Resins and Gel Compositions Made Therefrom

Abstract

A method of stabilizing a resorcinol-aldehyde resin comprises heating a resorcinol-aldehyde resin in the substantial absence of an acid or base catalyst at a temperature from about 130° C. to about 180° C. for a sufficient amount of time to render the resin stable in an aqueous solution, wherein the resorcinol-aldehyde resin prior to heating is a novolak resin. The stabilized resins have many useful applications. For example, they can be used to make aerogels and xerogels. They also can be used to make dipping solutions to improve the adhesion between rubber and tire cords in a tire, belt, or hose.

1 . A method of stabilizing a resorcinol-aldehyde resin, comprising: heating a resorcinol-aldehyde resin in the substantial absence of an acid or base catalyst at a temperature from about 130° C. to about 180° C. for a sufficient amount of time to render the resorcinol-aldehyde resin stable in an aqueous solution, wherein the resorcinol-aldehyde resin prior to the heating is a novolak resin. 
     
     
         2 . The method of  claim 1 , wherein the resorcinol-aldehyde resin is at least partially soluble in water. 
     
     
         3 . The method of  claim 1 , wherein the resorcinol-aldehyde resin is obtainable by reacting a resorcinol compound with an aldehyde compound. 
     
     
         4 . The method of  claim 3 , wherein the resorcinol compound is represented by formula (I): 
       
         
           
           
               
               
           
         
       
       where each of R 1  and R 2  is independently H, OH, C 1-5  alkyl, or OR 3  where R 3  is a C 1-5  alkyl or C 1-5  aryl, and that at least one of R 1  and R 2  is OH. 
     
     
         5 . The method of  claim 3 , wherein the aldehyde compound is formaldehyde, methyl formcel, acetaldehyde, propionaldehyde, butyraldehyde, crotanaldehyde, cinnamaldehyde, benzaldehyde, furfural, acetone, methyl ethyl ketone, or a mixture thereof. 
     
     
         6 . The method of  claim 3 , wherein the aldehyde compound is formaldehyde. 
     
     
         7 . The method of  claim 3 , wherein the resorcinol compound is unsubstituted resorcinol and the aldehyde compound is formaldehyde. 
     
     
         8 . The method of  claim 3 , wherein the molar ratio of the resorcinol compound to the aldehyde compound is about 1:0.3 to about 1:0.7. 
     
     
         9 . The method of  claim 3 , wherein the molar ratio of the resorcinol compound to the aldehyde compound is about 1:0.45 to about 1:0.65. 
     
     
         10 . The method of  claim 1 , wherein the resorcinol-aldehyde resin is obtainable by reacting a resorcinol compound with an aldehyde compound in the presence of an acid or base catalyst, and the acid or base catalyst is substantially removed or neutralized before heating the resorcinol-aldehyde resin. 
     
     
         11 . The method of  claim 3 , wherein volatiles present in the reaction mixture are substantially removed before heating the resorcinol-aldehyde resin. 
     
     
         12 . The method of  claim 11 , wherein an aqueous solvent is added to the resorcinol-aldehyde resin after heating to make a stabilized solution of the resorcinol-aldehyde resin. 
     
     
         13 . The method of  claim 3 , wherein an aqueous solvent in the reaction mixture is not removed before heating the resorcinol-aldehyde resin. 
     
     
         14 . A stabilized resorcinol-aldehyde aqueous solution obtainable by a method comprising heating a resorcinol-aldehyde resin in the substantial absence of an acid or base catalyst at a temperature from about 130° C. to about 180° C. for a sufficient amount of time to render the resorcinol-aldehyde resin stable in an aqueous solution, wherein the resorcinol-aldehyde resin prior to the heating is a novolak resin. 
     
     
         15 . The stabilized resorcinol-aldehyde aqueous solution of  claim 14 , wherein the resorcinol-aldehyde resin is obtainable by reacting a resorcinol compound with an aldehyde compound, and the resorcinol compound is represented by formula (I): 
       
         
           
           
               
               
           
         
       
       where each of R 1  and R 2  is independently H, OH, C 1-5  alkyl, or OR 3  where R 3  is a C 1-5  alkyl or C 1-5  aryl, and that at least one of R 1  and R 2  is OH. 
     
     
         16 . A dip solution for enhancing the adhesion between fabric or glass cords and rubber in a tire, hose, or belt comprising the stabilized resorcinol-aldehyde aqueous solution of  claim 14 . 
     
     
         17 . A gel obtainable from a stabilized resorcinol-aldehyde aqueous solution, wherein the stabilized resorcinol-aldehyde aqueous solution is obtainable by a method comprising heating a resorcinol-aldehyde resin in the substantial absence of an acid or base catalyst at a temperature from about 130° C. to about 180° C. for a sufficient amount of time to render the resorcinol-aldehyde resin stable in an aqueous solution, wherein the resorcinol-aldehyde resin prior to the heating is a novolak resin. 
     
     
         18 . The gel of  claim 17 , wherein the resorcinol-aldehyde resin is obtainable by reacting a resorcinol compound with an aldehyde compound, and the resorcinol compound is represented by formula (I): 
       
         
           
           
               
               
           
         
       
       where each of R 1  and R 2  is independently H, OH, C 1-5  alkyl, or OR 3  where R 3  is a C 1-5  alkyl or C 1-5  aryl, and that at least one of R 1  and R 2  is OH. 
     
     
         19 . The gel of  claim 17 , wherein the gel is a resorcinol-formaldehyde resin gel. 
     
     
         20 . The gel of  claim 17 , wherein the gel is an aerogel or xerogel. 
     
     
         21 . The gel of  claim 17 , wherein the method further comprises subsequently adding additional aldehyde and drying the stabilized resorcinol-aldehyde resin to obtain the gel. 
     
     
         22 . A carbon foam obtainable by carbonizing the gel of  claim 17 . 
     
     
         23 . The carbon foam of  claim 22 , wherein the foam has an average pore size from about 50 nm to about 200 nm. 
     
     
         24 . The carbon foam of  claim 22 , wherein the foam has a density in the range of about 35 mg/cc to 100 mg/cc. 
     
     
         25 . The carbon foam of  claim 22 , wherein the foam has an average pore size from about 2 nm to about 100 nm.