Stabilized phenolic resole resin compositions and their use

Abstract

This invention relates to a stabilized phenolic resole resin composition comprising a phenolic resole resin and an effective stabilizing amount of an ortho ester, such that the composition contains no more than about 1.0 weight percent of a polyisocyanate. The invention also relates to phenolic urethane binders prepared with the phenolic resole resin compositions, and the use of the binders to make foundry mixes, foundry shapes, and metal castings.

1 . A stabilized phenolic resole resin composition useful for preparing phenolic urethane binders, comprising an effective stabilizing amount of an ortho ester is selected from the group consisting of triethyl orthoformate, trimethyl orthoformate, and mixtures thereof such that said composition contains no more than about 1.0 weight percent of a polyisocyanate, where said weight percent is based upon the weight of said resin composition.  
     
     
         2 . The stabilized phenolic resole resin composition of  claim 1  which also contains a solvent selected from the group consisting of aromatic solvents, polar solvents, and mixtures thereof.  
     
     
         3 . The stabilized phenolic resole resin composition of  claim 2  wherein the stabilized phenolic resole resin composition comprises a polybenzylic ether phenolic resin prepared by reacting an aldehyde with a phenol such that the molar ratio of aldehyde to phenol is from 1.1:1 to 3:1 in the presence of a divalent metal catalyst.  
     
     
         4 . The stabilized phenolic resole resin composition of  claim 3  wherein the phenol used to prepare the phenolic resole resin of the stabilized phenolic resole resin composition is phenol.  
     
     
         5 . The stabilized phenolic resole resin composition of  claim 4  wherein the aldehyde used to prepare the phenolic resin of the stabilized phenolic resole resin composition is formaldehyde.  
     
     
         6 . The stabilized phenolic resole resin composition of  claim 5  wherein the amount of solvent in the resin composition is from 20 weight percent to 80 weight percent based upon the weight of the phenolic resin composition.  
     
     
         7 . The stabilized phenolic resole resin composition of  claim 6  wherein the amount of ortho ester is from about 0.1 weight percent to about 1.5 weight percent based upon the weight of the phenolic resin.  
     
     
         8 . The stabilized phenolic resole resin composition of  claim 7  wherein the phenolic resole resin of the stabilized phenolic resole resin composition is an alkoxy-modified benzylic ether phenolic resole resin and the catalyst used to prepare said resin is a divalent zinc salt.  
     
     
         9 . The stabilized phenolic resole resin composition of  claim 8  wherein said composition contains no more than about 0.5 weight percent of a polyisocyanate.