Process for producing vinylamine-vinyl alcohol copolymer and use of the copolymer

Abstract

Disclosed is a process for producing a powdered water-soluble polymer comprising hydrolyzing a copolymer comprising an N-vinylamide unit and a vinyl acetate unit while dispersed in water under a basic condition and then washing the resulting powdered water-soluble polymer with at least one washing liquid selected from an alcohol, water at 20° C. or lower, and salt water.

What is claimed is:  
     
         1 . A process for producing a powdered water-soluble polymer comprising hydrolyzing a copolymer comprising an N-vinylamide unit and a vinyl acetate unit while dispersed in water under a basic condition and then washing the resulting powdered water-soluble polymer with at least one washing liquid selected from an alcohol, water at 20° C. or lower, and salt water.  
     
     
         2 . The process according to  claim 1 , wherein the hydrolysis reaction mixture is once separated into liquid and solid, and the resulting copolymer powder is washed with the washing liquid.  
     
     
         3 . The process according to  claim 1 , wherein said N-vinylamide unit is an N-vinylformamide unit.  
     
     
         4 . The process according to  claim 1  wherein the molar ratio of said N-vinylamide unit to said vinyl acetate unit in said copolymer is 1:99 to 50:50.  
     
     
         5 . The process according to  claim 1 , wherein the hydrolysis of the copolymer is carried out in presence of a caustic alkali.  
     
     
         6 . The process according to  claim 1 , wherein the degree of hydrolysis of the copolymer is 20% or more.  
     
     
         7 . The process according to  claim 1 , wherein said washing liquid is a lower aliphatic alcohol.  
     
     
         8 . The process according to  claim 1 , wherein the washing is carried out until the total concentration of an acetate and a formate by-produced by the hydrolysis in the water-soluble polymer is reduced to 5000 ppm or less.  
     
     
         9 . The process according to  claim 1 , wherein said water-soluble polymer is precipitated from the hydrolysis reaction mixture containing 0.5 to 50% by weight of a salt.  
     
     
         10 . A surface coating composition for paper or a plastic film which comprises the water-soluble polymer obtained by the process according to  claim 1 .  
     
     
         11 . A dye fixing composition for fiber which comprises the water-soluble polymer obtained by the process according to  claim 1 .  
     
     
         12 . A hair setting composition which comprises the water-soluble polymer obtained by the process according to  claim 1 .  
     
     
         13 . A hair conditioning composition which comprises the water-soluble polymer obtained by the process according to  claim 1.