Coatings, oxygenated solvents

The impact these regulations and methods have had on solvent use is seen clearly in figs. 7.2 and 7.3 (Kirschner, 1994). Over the past 15 years the use of both hydrocarbon and chlorinated solvents has declined with only a minor increase in consumption of oxygenated solvents. In addition, while process solvents, consumer products and various miscellaneous applications have exhibited fairly constant solvent consumption, the cleaning and coatings industries have markedly decreased solvent use over... 

It has been estimated by Doolittle and Holden (T) that, excluding petroleum hydrocarbons, the protective coatings industry in 1933 consumed about 40% of chemicals classified as solvents. By 1949 only 25% of these solvents were used in coatings ( 5), and by 1972 it was estimated by Stewart (6) that only 14% of oxygenated solvents (which include ketones, esters, alcohols, and glycol ethers) were consumed by the coatings industry. The total consumption of these solvents in coatings was estimated at 1.9 billion pounds for 1972. 

Based on data of SRI International, the National Paint and Coatings Association (7) has reported the quantities of solvents used in manufacture of coatings, in thinning, in clean-up operations, and in dissolving resins supplied to the coatings industry (Table I). In 1981 the following quantities of solvents were used 955 million pounds of aliphatic hydrocarbons, 1215 of aromatic hydrocarbons, 1782 of oxygenated solvents, 21 of chlorinated solvents, and 34 of miscellaneous solvents. 

The oxygenated solvent in greatest use in coatings today (about 335 million Ib/yr) is methyl ethyl ketone. In 1932 Shell Chemical became the first commercial producer. It was made from n-butylene by hydration and subsequent dehydrogenation. Methyl ethyl ketone also is currently coproduced with acetic acid by the oxidation of n-butane by other manufacturers. 

Coatings solvents are also classified according to chemical nature as hydrocarbons, oxygenated solvents, and other , which are usually hydrocarbon derivatives. 

Oxygenated solvents - The principal oxygenated solvents for coatings are ketones, esters, glycol ethers, and alcohols. These are high purity synthetic compounds as opposed to the hydrocarbons, which are naturally derived chemical mixtures. The oxygenated solvents also offer much stronger solvency and partial to complete water miscibility. They are widely used as the active solvents for synthetic binders because of their ability to be blended to provide tailored solvency and evaporation rate. 

Solvents and diluents used in wood preservatives and coatings included hydrocarbons (aliphatic, cyclic, and aromatic), oxygenated solvents (ketones, esters, alcohols, and glycol ethers), and water. ... 

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