Dispersion and aqueous coating composition comprising the dispersion

Abstract

The present invention relates to a dispersion comprising an acryl-modified cellulose ester derivative (D) dispersed in an aqueous medium, wherein a hydrophobic acrylic resin (B) and a hydrophilic acrylic resin (C) are grafted onto a cellulose ester derivative (A) in the acryl-modified cellulose ester derivative (D). The dispersion has excellent long-term storage stability, and aqueous coating compositions comprising the dispersion can form coating films with excellent coating workability, solvent resistance, chemical resistance, water resistance, and excellent curability.

1 . A dispersion comprising an acryl-modified cellulose ester derivative (D) dispersed in an aqueous medium, wherein a hydrophobic acrylic resin (B) and a hydrophilic acrylic resin (C) are grafted onto a cellulose ester derivative (A) in the acryl-modified cellulose ester derivative (D). 
   
   
       2 . The dispersion according to  claim 1 , wherein the cellulose ester derivative (A) is cellulose acetate butyrate and/or cellulose acetate propionate. 
   
   
       3 . The dispersion according to  claim 1 , wherein the acid value of the acryl-modified cellulose ester derivative (D) is in the range of 10-150 mgKOH/g. 
   
   
       4 . The dispersion according to  claim 1 , wherein the amount of carboxyl group-containing radical-polymerizable unsaturated monomers in the radical-polymerizable unsaturated monomer mixture (b) used for synthesis of the hydrophobic acrylic resin (B) is less than 5 mass %, and the amount of carboxyl group-containing radical-polymerizable unsaturated monomers in the radical-polymerizable unsaturated monomer mixture (c) used for synthesis of the hydrophilic acrylic resin (C) is in the range of 5-95 mass %. 
   
   
       5 . The dispersion according to  claim 4 , wherein the acryl-modified cellulose ester derivative (D) is synthesized with the following ranges:
 Cellulose ester derivative (A): 3.0-90 parts by mass,   Radical-polymerizable unsaturated monomer mixture (b): 5.0-92 parts by mass,   Radical-polymerizable unsaturated monomer mixture (c): 5.0-92 parts by mass,   based on 100 parts by mass as the total of the cellulose ester derivative (A), the radical-polymerizable unsaturated monomer mixture (b) and the radical-polymerizable unsaturated monomer mixture (c).   
   
   
       6 . The dispersion according to  claim 5 , wherein the acryl-modified cellulose ester derivative (D) is produced by separate graft polymerization of the radical-polymerizable unsaturated monomer mixture (b) and radical-polymerizable unsaturated monomer mixture (c) onto the cellulose ester derivative (A). 
   
   
       7 . The dispersion according to  claim 6 , wherein the cellulose ester derivative (A) has at least one radical-polymerizable unsaturated group. 
   
   
       8 . The dispersion according to  claim 6 , wherein the radical polymerization initiator used for graft polymerization of the radical-polymerizable unsaturated monomer mixture (b) and/or radical-polymerizable unsaturated monomer mixture (c) onto the cellulose ester derivative (A) is an organic peroxide-based compound. 
   
   
       9 . An aqueous coating composition comprising the dispersion according to  claim 1 . 
   
   
       10 . A coated article obtained by coating the aqueous coating composition according to  claim 9 .