Scratch and abrasion resistant uv blocking glass coating

Abstract

A coating composition and method of making a scratch resistant UV blocking glass coating is described. The composition can include an aqueous colloidal silica. a bifunctional silanol coupling agent, tetraethylorthosilicate (TEOS), a UV absorber, and a water miscible solvent selected from glycol ethers, alkanols, keto alcohols, and combinations thereof. The molar ratio of the bi-functional silanol to TEOS is selected to provide scratch resistance coupled with water resistance.

What is claimed is: 
     
         1 . A method for preparing a coating composition, the method comprising:
 preparing a first blend of an aqueous colloidal silica and a water miscible solvent, the water miscible solvent selected from glycol ethers having a boiling point of less than 230° C., alkanols having 1 to 3 carbons, keto alcohols having a boiling point of less than 230° C., and combinations thereof;   adding a bi-functional silanol coupling agent to the first blend to form a second blend;   adding tetraethylorthosilicate (TEOS) to the second blend to form a third blend, wherein the molar ratio of TEOS to the bi-functional silanol is about 30:70 to 40:60;   adding a fourth blend to the third blend to form a fifth blend, the fourth blend comprising a UV absorber and the water miscible solvent;   coating the coating composition onto a glass substrate; and   heating the coated substrate to a surface temperature of about 230° C. to 500° C.   
     
     
         2 . The method of  claim 1  further comprising heating the second blend to a first elevated temperature. 
     
     
         3 . The method of  claim 1  further comprising maintaining the third blend below a second elevated temperature. 
     
     
         4 . The method of  claim 1  wherein the coating thickness is about 2.5 μm±0.5 μm. 
     
     
         5 . The method of  claim 1  further comprising blending each of the first blend, second blend, third blend, fourth blend, and fifth blend at a temperature between about 30° C. and about 50° C. 
     
     
         6 . The method of  claim 1  wherein the third blend is formed by addition of TEOS to the second blend over about one hour. 
     
     
         7 . A coating composition comprising
 an aqueous colloidal silica;   a bifunctional silanol coupling agent;   tetraethylorthosilicate (TEOS);   a UV absorber; and   a water miscible solvent,   
       wherein the molar ratio of the bi-functional silanol to TEOS is about 70:30 to 60:40 and the water miscible solvent is selected from glycol ethers having a boiling point of less than 230° C., alkanols having 1 to 3 carbons, keto alcohols having a boiling point of less than 230° C., and combinations thereof. 
     
     
         8 . The composition of  claim 7  wherein the water miscible solvent comprises one or more of 2-propoxyethanol, methanol, ethanol, or diacetone alcohol. 
     
     
         9 . The composition of  claim 7  wherein the UV absorber comprises 2,2′,4,4′-tetrahydroxybenzophenone. 
     
     
         10 . The composition of  claim 7  wherein the bi-functional silane coupling agent comprises a 3-glycidoxypropyltrialkoxysilane, a 3-isocyanatopropyltrialkoxysilane, or two or more thereof. 
     
     
         11 . The composition of  claim 7  further comprising a dye, a flow agent, or both. 
     
     
         12 . A coated glass article comprising a cured resin composition disposed on at least a portion of a glass substrate, the cured resin composition derived by
 coating the coating composition of any of  claims 7 - 11  onto at least a portion of a surface of a glass substrate to form a coated substrate; and   heating the coated substrate to a surface temperature of about 230° C. to 500° C. to form the coated glass article.   
     
     
         13 . The coated glass article of  claim 12  wherein the coating has a scratch resistance of at least 90 mN and a loss of less than about 1% UV blocking ability after immersing the coated glass in boiling water for 10 minutes. 
     
     
         14 . The coated glass article of  claim 12  wherein the coating has a scratch resistance of at least 100 mN and a loss of less than about 1% UV blocking ability after immersing the coated glass in boiling water for 10 minutes.