Coated plastic substrate

A laminate which comprises:

• a) a plastic substrate having a surface and a thickness of not less than about 0.1 mm and not more than about 10 mm;
• b) an adhesion promoter layer which is a plasma polymerized tetramethyldisiloxane deposited on the surface of the substrate at a power level in the range of about 5.times.10.sup.7 J/kg to about 5.times.10.sup.9 J/kg and in the substantial absence of oxygen, which adhesion promoter has a thickness of not less than about 1000 .ANG. and not more than 2000 .ANG.;
• c) a protective coating layer which is a plasma polymerized tetramethyldisiloxane deposited on the surface of the adhesion promoter layer at a power density from about 10.sup.6 J/kg to about 10.sup.8 J/kg in the presence of a sufficient stoichiometric excess of oxygen with respect to tetramethyldisiloxane to form an organosilicon compound having the formula SiO.sub.1.8-2.4 C.sub.0.3-1.0 and H.sub.0.7-4.0 that contains trapped water and at least one of the following functional groups:
• --Si--O--Si--, --Si--CH.sub.2 --, --Si--H, or --Si--OH;
• wherein the thickness of the protective coating layer is not less than about 0.1 micron and not greater than about 2 microns;
• and
• d) an SiO.sub.x layer which is a layer of a plasma polymerized tetramethyldisiloxane deposited on the surface of the protective coating layer, in the presence of a stoichiometric excess of oxygen, and at a power density of at least four times the power density used to form the protective coating layer, wherein the SiO.sub.x layer has a thickness of not less than about 0.05 micron and not more than about 1 micron.