Paint and other Organic Coatings

Painting aluminium most often serves a decorative purpose. This is true especially in the construction industry and in shipbuilding (with the exception of hulls in contact with seawater). Since aluminium is nontoxic, it needs to be coated with an antifouling paint compatible with aluminium (i.e. without copper and mercury salts) in order to prevent fouling. 

Since the corrosion resistance of the base metal itself is very good, the resistance of organic coatings is remarkable even after many years of exposure [21]. 

When the protecting effect of the coating eventually fades, possible corrosion of the aluminium base metal will not degrade the surface appearance, as observed in the case of rust runoff on steel. The renovation of paint coatings on aluminium will be less frequent than on other metals. 

Cathodic protection of steel by zinc was discovered in 1742 by Malouin. The industrial production of galvanised steel began in 1837 [22]. 

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A wide range of paints and other organic coatings is used for the protection of mild steel structures. Paints are used mainly for protection from atmospheric corrosion. Special chemically resistant paints have been developed for use on chemical process equipment. Chlorinated rubber paints and epoxy-based paints are used. In the application of paints and other coatings, good surface preparation is essential to ensure good adhesion of the paint film or coating. 

Paints and other organic coatings to protect exposed structures above the splash zone. 

Modem civilization consumes vast quantities of organic compounds. Coal, petroleum, and natural gas are primary sources of carbon compounds for use in production of energy and as starting materials for the preparation of plastics, synthetic fibers, dyes, agricultural chemicals, pesticides, fertilizers, detergents, rubbers and other elastomers, paints and other surface coatings, medicines and drugs, perfumes and flavors, antioxidants and other preservatives, as well as asphalts, lubricants, and solvents that are derived from petroleum. 

Less than 50 years ago, virtually all paint and other surface coating formulations were based on hydrocarbon solvents as the liquid phase. Following advances made in emulsion or latex polymer chemistry, resin systems became available which had the necessary properties of mechanical strength, durability and cost effectiveness such that today, emulsion paint dominates the decorative coatings area. This trend was assisted by the introduction of legislation which discouraged and, in some cases, prohibited the use of formulations which resulted in VOC (volatile organic carbon) emission to atmosphere. 

Chlorinated aromatics, including monochlorobenzene (MCB), o-dichloroben-zene (o-DCB), and p-dichlorobenzene (p-DCB), are the major chlorinated aromatic species produced on an industrial scale. MCB is used as both a chemical intermediate and a solvent. As an intermediate, it is used to produce chloroni-trobenzene, pesticides, and pharmaceutical products. In solvent applications, MCB is used in the manufacture of isocyanates. Its high solvency allows it to be used with many types of resins, adhesives, and coatings. The o-dichlorobenzene is used primarily for organic synthesis, especially in the production of 3,4-dichlo-roaniline herbicides. Like MCB, it can be used as a solvent, especially in the production of isocyanates. It is also used in motor oil and paint formulations. The p-dichlorobenzene is used as a moth repellent and for the control of mildew and fungi. It also is used for odor control. It is a chemical intermediate for the manufacture of pharmaceuticals and other organic chemicals. 

Solvent for paint, coatings, gums, oils and resins raw material in the production of benzene, phenol, and other organic solvents blending of petrol... 

Use Raw material for plastics, solvents, dyes, dmgs, and other organic chemicals. The crude or refined product or fractions thereof are also used for waterproofing, paints, pipe coating, roads, roofing, and insulation and as pesticides and sealants. 

United States industries use an estimated 1.5 billion liters of paints and other coatings per year, and much of this is applied by spraying. Each liter sprayed from a canister releases an average of 550 grams of volatile organic compounds (VOCs). Some of these VOCs are hazardous air pollutants. 

Figure 20-3 shows the results of the accelerated weathering tests on our inorganic coating material and other organic paints. Luster retention rate is defined as follows ... 

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