Thinning, paint manufacturing

Paint and varnish manufacturing Resin manufacturing closed reaction vessel Varnish cooldng-open or closed vessels Solvent thinning Acrolein, other aldehydes and fatty acids (odors), phthalic anhydride (sublimed) Ketones, fatty acids, formic acids, acetic acid, glycerine, acrolein, other aldehydes, phenols and terpenes from tall oils, hydrogen sulfide, alkyl sulfide, butyl mercaptan, and thiofen (odors) Olefins, branched-chain aromatics and ketones (odors), solvents Exhaust systems with scrubbers and fume burners Exhaust system with scrubbers and fume burners close-fitting hoods required for open kettles Exhaust system with fume burners... 

Muratic acid is powerful. Thick gloves were worn along with eye protection. Using a stainless steel teaspoon, about 1-5ml (1 teaspoon) of muratic acid was poured into a pickle jar that contained roughly 3/4 filtered water (15 ounces or about 500ml.) The pickle jar was previously washed twice in a dishwasher in an attempt to ensure sterility. Under the lid of the pickle jar the manufacturer had painted on a thin ring of some type of latex or rubber to help seal the jar. The mixture of water and acid do not seem to affect the ring (it doesn t dissolve or melt the latex in any way) so the jar and its lid were used. 

Acrylic paints have compositions similar to water-based house paints. Since they are synthetic, manufactures can design paints that fulfill specific requirements and that are the same from tube to tube. Because water is the main vehicle such paints are largely odorless. They are not completely odorless because while the overwhelming majority of the vehicle is water, there are often minute amounts, generally 1%-10%, of organic liquid added to help the particles of polymer remain sufficiently flexible so that they will lay down a thin smooth coating. 

I ll never forget the time I had to work on a computer that had been used on the manufacturing floor of a large equipment manufacturer. The computer and keyboard were covered with a black substance that would not come off. (I later found out it was a combination of paint mist and molybdenum grease.) There was so much diesel fume residue in the power supply fan that it would barely turn. Also, the insides and components were covered with a thin, greasy layer of muck. To top it all off, it smelled terrible ... 

Among the xylene isomers p-xylene is commercially the most important and highest volume chemical because p-xylene is the critical feed stock for production of purified ter-ephthalic acid or dimethyl terephthalate which is converted to synthetic fibers. O-xylene is the next important isomer which is used for manufacture of phthalic anhydride. M-xylene is commercially the least important isomer and more often than not it is not separated as a pure product and is sold as a component of mixed xylenes along with ethyl benzene as a solvent or as a thinning agent in the paint industry. 

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. 

A coating flow is a fluid flow in which a large surface area is covered with one or more thin, uniform liquid layers. A summary of work in this field may be found in the review article of Ruschak (1985). In general, though not always, the film laid down is subsequently dried or cured. Examples of technical importance include the manufacture of synthetic membranes, photographic film, and the more prosaic application of painting. 

Thin coatings not only are used for mechanical protection and lubrication, but are widely applied to protect against corrosion and chemical reaction [47-49]. The steel body of a car is first covered by a zinc layer, which is further treated in a phosphate bath, to promote the adhesion of the paint. Damaging this sandwich structure, by breaking one of these layers, results in quick corrosion of the car body rust. The improvement in the quality of this protective coating during the last 20 years is shown by the increase of the duration of the corrosion warranty proposed by car manufacturers (from 2 years less than 15 years ago, to 8 years at the present time). 

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