Film-forming silane crosslinked acrylate interpolymers having water-barrier properties

A film-forming polymeric composition having water-barrier properties at pH's below about 8.5 and solubilizable at pH's above about 9, said composition comprising a silane-crosslinked interpolymer of about 1.5 to 4 parts by weight of a first monomer selected from the group consisting of the alkyl acrylates wherein the alkyl group has from one to eight carbon atoms, and about 1 part by weight of a second monomer selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride and itaconic acid, and about 0.9 to 1.5% by weight, based on the combined weight of said first and second monomers, of a crosslinking monomer selected from the group consisting of the silane monomers having this structural formula:

• ##EQU3## wherein:
• R is selected from the group consisting of CH.sub.3 --, CH.sub.3 CH.sub.2 --, CH.sub.3 O-- and CH.sub.3 CH.sub.2 O--;
• R.sub.1 and R.sub.2 are each selected from the group consisting of CH.sub.3 -- and CH.sub.3 CH.sub.2 --;
• R.sub.3 is selected from the group consisting of H--, CH.sub.3 -- and CH.sub.3 CH.sub.2 --;
• and n is 0 or a positive integer not greater than 8.

A method of forming a polymeric composition having film-forming characteristics such that the resultant film has barrier properties at neutral pH's in the range of between about 4.5 and about 8.5 and yet is solubilizable at a pH substantially outside said neutral range, said method comprising the step of interpolymerizing at elevated temperatures about 0.5 to 5 parts by weight of a first monomer selected from the group consisting of alkyl acrylates wherein the alkyl group has from one to eight carbon atoms, and about 1 part by weight of a second monomer selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, tert.-butylaminoethyl acrylate and tert.-butylaminoethyl methacrylate, and about 0.9 to 1.5% by weight, based on the combined weight of said first and second monomers, of a cross-linking monomer selected from the group consisting of the silane monomers having the structural formula:

• ##EQU4## wherein:
• R is selected from the group consisting of CH.sub.3 --, CH.sub.3 CH.sub.2 --, CH.sub.3 O-- and CH.sub.3 CH.sub.2 O;
• R.sub.1 and R.sub.2 are each selected from the group consisting of CH.sub.3 --, and CH.sub.3 CH.sub.2 --;
• R.sub.3 is selected from the group consisting of --H, CH.sub.3 --, and CH.sub.3 CH.sub.2 --;
• and n is 0 or a positive integer not greater than 8;
• in the presence of a catalytic amount of a polymerization catalyst therefor.