Compositions and methods for sealing natural stone tiles and natural stone articles

Abstract

The present invention relates to a method of sealing natural stone tiles and stone articles by applying and curing by UV radiation a liquid, solventless sealant onto natural stone tiles and articles to provide permanent protection, abrasion resistance, chemical and stain resistance and resistance to mold and other biological growth stains. The UV-curable solventless sealing composition comprises an effective amount of carboxyl functional, UV-curable reagent to provide for adhesion of the cured coating to the stone article. Additionally, the method describes the application of an optional liquid primer sealant comprising a UV-curable aqueous dispersion of an acrylate-functional resin.

1 . A method for applying a sealant to natural stone tile and articles comprising:
 a) cleaning the natural stone tile or article;   b) conditioning the natural stone tile or article with a regulated amount of heat;   c) conditioning a liquid UV-curable solventless sealant comprising a mixture of acrylate oligomers and monomers, photoinitiators, aluminum oxides, silicon oxides, carboxyl-functional reagents, flow and leveling agents and a biocide by heating;   d) applying the liquid UV-curable solventless sealant to the natural stone tile or article, and;   e) curing of the applied UV-curable solventless sealant by exposure to UV radiation.   
   
   
       2 . The method of  claim 1  wherein steps b), d) and e) are conducted in a controlled time sequence. 
   
   
       3 . The method of  claim 1  wherein the surface temperature of the stone tile or article is about 40° C. to about 60° C. at the time of application of the liquid UV-curable solventless sealant to the stone tile or article. 
   
   
       4 . The method of  claim 1  wherein the conditioned liquid UV-curable sealant is maintained at a temperature from about 30° C. to about 50° C. during application of the sealant to the natural stone tile or article. 
   
   
       5 . The method of  claim 1  wherein the liquid UV-curable sealant is applied to the sealant to the natural stone tile or article by spray, roller, spray curtain or mist. 
   
   
       6 . The method of  claim 1  wherein the liquid UV-curable sealant is applied to the stone, tile or article by ultrasonic spray. 
   
   
       7 . The method of  claim 1  wherein the liquid UV-curable sealant is applied to the stone, tile or article by low volume, low pressure spray. 
   
   
       8 . The method of  claim 1  wherein the liquid UV-curable sealant additionally comprises a carboxyl-functional reagent that is UV curable. 
   
   
       9 . The method of  claim 8 , wherein the carboxyl-functional reagent is selected from a group consisting of one or more acrylate or methacrylate functional monomers. 
   
   
       10 . The method of  claim 9 , wherein the carboxyl-functional acrylate functional monomer is beta-carboxyethyl acrylate (B-CEA). 
   
   
       11 . The method of  claim 1  wherein the carboxyl-functional reagent comprises from about 1% to about 4% by weight of the liquid UV-curable solventless sealant. 
   
   
       12 . The method of  claim 1  wherein the natural stone tiles and articles comprise one or more of marble, travertine and limestone. 
   
   
       13 . The method of  claim 12 , wherein the liquid UV-curable solventless sealant imparts an enhanced and color controlled appearance of the surface and underlying substrate of the natural stone tile or article. 
   
   
       14 . The method of  claim 1  wherein the UV radiation is supplied by solid-state light-emitting diodes. 
   
   
       15 . The method of  claim 1 , further comprising applying a UV-curable water-based primer/sealant to said natural stone tiles and articles before application of the liquid UV-curable solventless sealant. 
   
   
       16 . The method of  claim 15 , wherein the surface temperature of the stone tile or article before application of the UV-curable water-based primer/sealant is at least 30° C. 
   
   
       17 . The method of  claim 15 , wherein the UV-curable water-based primer/sealant is applied by spray, roller, spray curtain or mist. 
   
   
       18 . The method of  claim 15 , wherein the UV-curable water-based primer/sealant is applied to the stone, tile or article by ultrasonic spray. 
   
   
       19 . The method of  claim 15 , wherein the UV-curable water-based primer/sealant is applied to the stone, tile or article by low volume, low pressure spray. 
   
   
       20 . The method of  claim 15 , wherein the liquid UV-curable solventless sealant is applied in a controlled time sequence onto the natural stone tile or article after application of the UV-curable water-based primer/sealant. 
   
   
       21 . The method of  claim 20 , wherein the liquid UV-curable solventless sealant is applied by ultrasonic spraying. 
   
   
       22 . The method of  claim 20 , wherein the liquid UV-curable solventless sealant is applied to the stone, tile or article by low volume, low pressure spray. 
   
   
       23 . The method of  claim 20 , wherein the sealants are exposed to UV radiation after application. 
   
   
       24 . The method of  claim 23 , wherein said UV radiation is supplied by light emitting diodes. 
   
   
       25 . The method of  claim 20 , wherein the conditioning of the stone tiles or articles, the application of the UV-curable water-based primer/sealant and the liquid UV-curable solventless sealant and the curing of the sealants by UV radiation is performed on a continuous moving belt for transporting the tiles and articles at speeds of up to about 5 feet per minute and over a total length of about 20 feet or less.