Coating composition for forming hydrophilic coating film

Abstract

To provide a coating composition capable of forming a hydrophilic coating film which has high transparency and which is excellent in abrasion resistance (adhesion), hydrophilicity (anti-fogging, wettability and anti-fouling properties) and hydrophilic durability. A coating composition for forming a hydrophilic coating film, which comprises boehmite particles, silica particles, a binder and water, wherein the crystallite diameter of the boehmite particles, as calculated from the diffraction peak of the (120) plane, is from 20 to 50 nm, the average particle diameter of the silica particles is from 5 to 50 nm, the proportion of the boehmite particles is from 20 to 80 mass % based on the total amount of the boehmite particles and the silica particles, and the proportion of the binder is from 0.5 to 15 parts by mass per 100 parts by mass in total of the boehmite particles and the silica particles. The article having a hydrophilic coating film on a surface of a base material, has a hydrophilic coating film formed from the above coating composition.

1 . A coating composition for forming a hydrophilic coating film, which comprises boehmite particles, silica particles, a binder and water, wherein:
 the crystallite diameter of the boehmite particles, as calculated from the diffraction peak of the (120) plane, is from 20 to 50 nm,   the average particle diameter of the silica particles is from 5 to 50 nm,   the proportion of the boehmite particles is from 20 to 80 mass % based on the total amount of the boehmite particles and the silica particles, and   the proportion of the binder is from 0.5 to 15 parts by mass per 100 parts by mass in total of the boehmite particles and the silica particles.   
     
     
         2 . The coating composition according to  claim 1 , wherein the solid content concentration is from 0.1 to 20 mass %. 
     
     
         3 . The coating composition according to  claim 1 , wherein the binder is a water-soluble organic binder. 
     
     
         4 . The coating composition according to  claim 1 , wherein the binder is a water-soluble polyvinyl alcohol. 
     
     
         5 . The coating composition according to  claim 1 , which has a pH of from 2.5 to 7. 
     
     
         6 . The coating composition according to  claim 1 , which further contains a water-soluble alcohol, wherein the proportion of the water-soluble alcohol is from 10 to 70 mass %, based on the total amount of the water and the water-soluble alcohol. 
     
     
         7 . An article having, on a surface of a base material, a hydrophilic coating film formed from the coating composition as defined in  claim 1 . 
     
     
         8 . The article according to  claim 7 , wherein the hydrophilic coating film has a film thickness of from 100 to 700 nm. 
     
     
         9 . The article according to  claim 7 , wherein the material for the base material is a resin material. 
     
     
         10 . The article according to  claim 7 , wherein the material for the base material is a fluororesin.