Industrial experience during the past fifteen years has shown that chlorinated rubber is an outstanding film-forming material from which corrosion-resistant coatings may be formulated.
Correct formulation has a marked beneficial effect on resistance of chlorinated rubber systems to corrosive solutions or atmospheres. For maximum chemical resistance the types of modifiers for chlorinated rubber are restricted to chemically inert resins and plasticizers which must be formulated properly to give optimum film properties and satisfactory weathering resistance.
If proper precautions in selecting the modifying components are not considered, corrosion resistance of chlorinated rubber coatings may be seriously impaired. For example, alkali resistance rapidly diminishes when the vehicle is modified with saponifiable resins or plasticizers. Similar deficiencies develop if components are incorporated which are not themselves unaffected by acids or salts.
Pigmented coatings in which the film consists of 50-60 percent chlorinated rubber, 15-20 percent Arochlor 5460, Chlorowax 70 or hard coumarone resins, etc., and 25-30 percent Clorafin 42-S, Arochlor 1254 or Cumar P-10, etc., are shown to provide highly effective protection to corrosion. Panels with such coatings tested in the salt fog (ASTM B-117-44T, 20 percent sodium chloride, 100° F) and in tap water immersion (100° F) in comparison with many other types of coatings illustrate their value when exposed to salt corrosion or water.
Because best performance cannot be obtained without suitable primers, a comparison of chlorinated rubber and other types of primers was undertaken in these tests. It is shown that pigmentation of chlorinated rubber primers is equally as important as that previously established with other vehicles. When properly formulated with corrosion-resistant pigments, chlorinated rubber primers together with chlorinated rubber topcoats afford a high degree of protection.
Numerous case histories of commercial use in varied maintenance problems where chemical resistance is essential establish the economical merit of such coatings. Among the fields discussed are acid plants, paper mills, water works, industrial machinery, sewage disposal plants and concrete construction protected by chlorinated rubber.
One feature of chlorinated rubber coatings has led to their acceptance for industrial maintenance. They are applicable by brushing or spraying to surfaces which cannot be physically prepared by ideal procedures. Chlorinated rubber, like most coatings, gives best results over rust-free, clean metal to which efficient primers are applied. The outstanding feature of chlorinated rubber, however, is that it affords reasonably good protection over many types of undercoats or over poorly prepared surfaces.
