Basic liquid composition suitable for producing transparent coatings or varnishes on solid surfaces, process for preparation of such varnishes, and varnishes produced thereby

Claim 1

A stable basic liquid composition of matter suitable for forming transparent coatings on surfaces selected from the group consisting of mineral glass, organic glasses of thermoplastic polymethacrylate and polycarbonate materials, and heat hardenable diallylglycol polycarbonate materials, and having a storage stability of at least 3 months at 15° C., comprising in solution in at least one organic solvent, from 10 to 40% by weight of a hardenable organo-silicic compound corresponding to the compound resulting from effecting a first hydrolysis reaction at a temperature lower than 50° C. in the presence of a carboxylic acid and water, on at least one alkoxysilane compound (A) of formula R' n SI(OR) 4-n in which n=1 or 2, R represents a radical selected from the group consisting of alkyl radicals with 1 to 4 carbon atoms, the alkyloxyalkyl and acyl radicals, and R' represents a radical selected from the group consisting of alkyl, alkylene, aryl, aralkyl, aklylaryl and alkylenearyl radicals, together with a small amount of Si(OR") 4 , wherein R" is alkyl or alkyloxyalkyl, removing under vacuum of volatile alkanol formed in the course of said first hydrolysis and effecting a second hydrolysis at a temperature lower than 40° C., on a mixture of (1) said first hydrolyzate resulting from said first hydrolysis, and which first hydrolyzate has been concentrated, then rediluted with a solvent less volatile than said alkanol of said first hydrolysis reaction and consisting of a mixture of C 1 -C 4 -alkanols, and (2) at least one alkoxysilane compound (C) of formula R'"SI(OR 1 ) 3 , in which R'" represents a radical selected from the group consisting of epoxyalkyl and epoxyalkyloxyalkyl radicals, and R 1 represents a C 1 -C 4 -alkyl radical, then adjustment of pH of the resulting medium to between 3.5 and 5.5 through addition of an organic base.