Caustic-resistant polymer coatings for glass

Claim 1

Returnable glass bottles for carbonated beverages, said bottles being coated on the outer surfaces with a clear, cross-linked resin providing abrasion resistance and protection from flying glass in care of fracture, said coating being caustic-resistant, exhibiting strong adherence to glass even after repeated treatments with 5% aqueous NaOH at 80° C, said clear, abrasion- and causticresistant coating being at least 8 mils thick and comprising: 1. a cured primer layer on the glass, and 2. an outer layer of a copolymer of ethylene, said primer layer (1) consisting essentially of A from 0.5 to 5% by weight of an organofunctional silane of the formula (RO-- 3 Si (CH 2 -- x R 1 , where Ro-- is a hydrolyzable alkoxy group in which R is an alkyl radical of 1 to 4 carbon atoms, R 1 is a functional group selected from --NH 2 , ##STR8## and x is an integer from 1 to 4, inclusive, B. an epoxy resin, C. a curing agent selected from the group consisting of amines and reactive polyamides containing excess amine groups, and optionally at least one member of the group consisting of D. a water-soluble metal salt, and E. diethylene glycol monoethyl ether, and the copolymer of said outer layer (2) consisting essentially of a random copolymer of ethylene in which the alpha, beta-unsaturated carboxylic acid is selected from the group consisting of acrylic acid and methacrylic acid having from 10% to 100% of the carboxyl groups ionized by metal ions having an ionized valence from one to three, inclusive, and in which the ethylene content of the copolymer is at least 70 mol %, based on the copolymer, the alpha, beta-unsaturated carboxylic acid content of said copolymer is from 0.2 to 5 mol %, inclusive, based on said copolymer, and any third monomer component optionally copolymerized in said copolymer is a monoethylenically unsaturated monomer.