Sol gel barrier films
AssigneeInternational Paper Company
InventorRaymond A. Volpe
Life of this patent
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Abstract
A relaxed sol-gel composition and a coated substrate article which is produced therefrom. A tetrafunctional alkoxide silicate is hydrolyzed in an aqueous solution together with a Lewis acid or metal chelate catalyst with optional protic acid until a viscosity of 2600-3200 cps is obtained to form a crosslinked sol-gel polymer composition. The polymer is relaxed by diluting it with water or water plus alcohol optionally containing a Lewis acid or metal chelate until a viscosity of about 1 cps is obtained while not depolymerizing the polymer. The relaxed polymer has substantially no visible polymer particles. The relaxed polymer composition is uniformly coating a substrate and dried without requiring an in-situ curing.
Claims20
A method of producing a relaxed sol-gel composition which comprises
- (a) hydrolyzing a tetrafunctional alkoxide silicate in an aqueous solution comprising water or water plus a C.sub.1 to C.sub.4 alcohol, and an acid catalyst selected from the group consisting of a protic acid, a Lewis acid, a metal chelate, a Lewis acid plus a protic acid, and a metal chelate plus a protic acid, until a viscosity of 2600-3200 cps is obtained to thereby produce a crosslinked sol-gel polymer composition;
- (b) relaxing the crosslinked sol-gel polymer composition and effecting hydrolysis of any residual alkoxyl groups thereof by diluting the crosslinked sol-gel polymer composition with water or water plus a C.sub.1 to C.sub.4 alcohol optionally containing a Lewis acid or metal chelate until a viscosity of about 0.5 to about 10 cps is obtained to thereby produce a relaxed sol-gel polymer composition while substantially not depolymerizing said polymer and which relaxed sol-gel polymer composition has substantially no visible polymer particles therein;
- and wherein at least one of steps (a) and (b) is conducted with a Lewis acid or metal chelate.
A method of producing a coated substrate article which comprises
- (a) hydrolyzing a tetrafunctional alkoxide silicate in an aqueous solution comprising water or water plus a C.sub.1 to C.sub.4 alcohol, and an acid catalyst selected from the group consisting of a protic acid, a Lewis acid, a metal chelate, a Lewis acid plus a protic acid, and a metal chelate plus a protic acid, until a viscosity of 2600-3200 cps is obtained to thereby produce a crosslinked sol-gel polymer composition;
- (b) relaxing the crosslinked sol-gel polymer composition and effecting hydrolysis of any residual alkoxyl groups thereof by diluting the crosslinked sol-gel polymer composition with water or water plus a C.sub.1 to C.sub.4 alcohol optionally containing a Lewis acid or metal chelate until a viscosity of about 0.5 to about 10 cps is obtained to thereby produce a relaxed sol-gel polymer composition while substantially not depolymerizing said polymer and which relaxed sol-gel polymer composition has substantially no visible polymer particles therein;
- and wherein at least one of steps (a) and (b) is conducted with a Lewis acid or metal chelate;
- (c) coating the substrate with a substantially uniform coating of the relaxed sol-gel polymer composition at a thickness not in excess of that which would provide a substantially crack-free layer on the substrate when dried;
- and
- (d) drying the relaxed sol-gel polymer composition to provide a substantially crack-free layer on the substrate.
Dependencies are inferred from the claim text.