Method of making protective coating for thermoplastic transparencies

A method for preparing an acid-resistant and abrasion-resistant aircraft transparency, the method comprising:

• (a) providing an aircraft transparency;
• (b) applying a silica-free protective coating precursor composition to at least one surface of the aircraft transparency, wherein the silica-free protective coating precursor composition comprises:
• (i) a multifunctional ethylenically unsaturated ester of acrylic acid, a multifunctional ethylenically unsaturated ester of methacrylic acid, or a combination thereof;
• and
• (ii) an acrylamide of the formula:
• ##STR5## wherein:
• (A) R.sup.1 and R.sup.2 are each independently hydrogen, a (C.sub.1 -C.sub.8) alkyl group optionally having hydroxy, halide, carbonyl, and amido functionalities, a (C.sub.1 -C.sub.8)alkylene group optionally having carbonyl and amido functionalities, a (C.sub.1 -C.sub.4)alkoxymethyl group, a (C.sub.4 -C.sub.18) aryl group, a (C.sub.1 -C.sub.3)alk(C.sub.4 -C.sub.8)aryl group, and a (C.sub.4 -C.sub.18)heteroaryl group;
• with the proviso that only one of R.sup.1 and R.sup.2 is hydrogen;
• and
• (B) R.sup.3 is hydrogen, a halogen, or a methyl group;
• and
• (c) exposing the protective coating precursor composition to conditions to cure the composition and form a protective coating on at least one surface of the thermoplastic transparency.