Water-dispersible polysaccaride derivatives of reduced glyoxal content, and a process for decreasing the glyoxal content in glyoxal-crosslinked polysaccharide derivatives

Abstract

A description is given of glyoxal-treated polysaccharide derivatives which, to decrease the unbound glyoxal, are treated with an aqueous solution of one or more water-soluble aluminium salts, or one or more water-soluble borates, or a combination of one or more water-soluble aluminium salts and one or more water-soluble borates, and, if appropriate, with suitable buffer substances to set the pH, and then dried. A description is likewise given of a process for decreasing the content of unbound glyoxal in glyoxal-treated polysaccharide derivatives.

1 - 10 . (canceled) 
     
     
         11 . A process for decreasing the amount of unbound glyoxal in glyoxal-crosslinked cellulose ether derivatives, comprising:
 adding water-soluble borates to a glyoxalating mixture comprising water, glyoxal, and an untreated cellulose ether derivative selected from the group consisting methyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, methyl ethyl cellulose, methyl ethyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, methyl hydroxyethyl hydroxypropyl cellulose, ethyl hydroxyethyl hydroxypropyl cellulose, methyl carboxymethyl cellulose, ethyl carboxymethyl cellulose, propyl cellulose, isopropyl cellulose, and cyclohexyl cellulose.   
     
     
         12 . The process of  claim 11 , wherein the untreated cellulose ether derivative is selected from the group consisting of methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, methyl cellulose and mixtures thereof. 
     
     
         13 . The process of  claim 11 , wherein the untreated cellulose ether derivative is in the form of a filter cake obtained after hot water washing. 
     
     
         14 . The process of  claim 11 , wherein the amount of the water-soluble borate is less than 0.5 part by weight per part by weight of glyoxal. 
     
     
         15 . The process of  claim 11 , wherein the water-soluble borate is sodium tetraborate. 
     
     
         16 . The process of  claim 11 , wherein the glyoxalating mixture further comprises a buffer substance for adjusting the pH value, said buffer substance being selected from the group consisting of salts of citric acid and salts of phosphoric acid. 
     
     
         17 . The process of  claim 11 , wherein extraction of dried and ground glyoxal-crosslinked cellulose ether derivative with tetrahydrofuran reveals less unbound glyoxal by weight than would have occurred in the absence of the water-soluble borates.