Ultraviolet chlorinated rubber

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

Chlorinated rubber, e.g. Duroprene (ICI Figure A3.7), is a saturated polymer. Although more stable than rubber, it is sensitive to light and ultraviolet, probably in a similar fashion to PVC, resulting in oxidation and discoloration. Chlorinated rubber can react with various pigments such as zinc oxide, copper salts, Prussian blue (ferric ferrocyanide) and ultramarine to form cross-Unks. 

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