Coatings solvent applications

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. 

Butanol is used as a direct solvent in paints and other surface coatings. It acts syneigistically with butyl acetate as a latent solvent system for nitrocellulose lacquers and thinners to give a solvent system stronger than either solvent alone. Other direct solvent applications for -butyl alcohol are in the formulation of pharmaceuticals, waxes, and resins. 

Coatings, antireflective Coatings applications Coating solvent Coaxial cable... 

Pretreatment primers. In this method of use the silane may be applied from a solvent solution, by vapour phase deposition or by plasma deposition although solvent application is the more usual. The solution usually contains water and silane at a concentration of 1-2 wt%. The applied film may be water washed before subsequent coating/bonding and/or heat cured. The solvent(s) used may be important in both the stability of the solution and the performance, particularly in the wet adhesion. It has been shown that the presence of water either in the solution or as a final rinse is important, particularly in the case of AAMS and presumably other silanes [1]. Other factors which are important include the concentration of silane the pH of the solution the thickness of the silane film deposited. 

Over the last 30 years, ethanol s role as a solvent has increased sharply, while its role as a chemical intermediate has declined. In 1990, 59% of the 890 x 106 L demand was used for solvents and the remaining 41% was used for chemical intermediates (283). In 1960, solvents accounted for only 24% of the demand. The 1990 solvent uses were toiletries and cosmetics, 33% coatings, inks, and proprietary blends, 29% deteigents and household cleaners, 14% external pharmaceuticals, 7% insecticides and disinfectants, 7% and miscellaneous, 10%. Ethanol demand for solvent applications has been fairly stable in recent years, growing at an average annual rate of 2%. VOC regulations could impact its solvent use, particularly in areas like California, where ethanol in aerosols like hair spray and deodorants have come under scrutiny. 

The key industrial applications and markets for normal and isobutanol and 2-ethylhexanol are discussed. As will be noted, the C4 oxo alcohols find use primarily within the coatings industry, either as solvents, per se, or as intermediates to manufacture solvents or protective coatings chemicals. Applications for 2-ethylhexanol, while numerous and varied, are basically oriented toward the manufacture of plasticizers for polyvinyl chloride. Total U.S. consumption of these alcohols in 1979 was approximately 1.3 billion pounds -730 million pounds of n-butanol, 190 million pounds of isobutanol, and 380 million pounds of 2-ethylhexanol. The consumption pattern is summarized in Table II and described in the following sections ... 

Demand for n-butanol as n-butyl acetate accounts for about 13 percent of domestic consumption of the alcohol. This acetate ester is a general purpose coatings solvent with particular application in nitrocellulose lacquers and moisture cured urethane coatings formulations. n-Butyl acetate is the traditional medium boiling solvent for nitrocellulose lacquers and, as such, is the standard by which other solvents are compared. 

Kreiner M, Parker MC (2005) Protein-coated microcrystals for use in organic solvents application to oxidoreductases. Biotechnol Lett 27 1571-1577... 

Isopropyl alcohol is an excellent solvent with a blend of polar, nonpolar, and hydrogenbonding character that makes it useful in a broad spectrum of applications. Its moderate volatility makes it convenient for uses involving evaporation or recovery by distillation. Thus, it is no surprise that much of IPA s consumption is for solvent uses. In North America in 1999 about 1.2 billion lb of IPA were consumed. Major uses were solvent applications, 47 percent isopropylamines, 15 percent, esters and ketones, 20 percent and others, including pharmaceuticals, 18 percent. The total demand in 1999 was significantly less than the 1.9 billion lb recorded for 1978. This downward trend is not unique to IPA and is primarily a result of regulatory pressure in the United States to decrease emissions of VOCs in coating and other applications. 

Solvent applications account for almost 95 percent of all MEK consumption the rest goes to chemical uses such as MEK peroxide and methyl ethyl ketoxime. The solvent applications include surface coatings, adhesives, lube oil dewaxing, magnetic tape manufacture, and printing inks. Production of MEK in 1999 totaled almost 690 million lb. 

In terms of general solvency, solvents may be described as active solvents, latent solvents, or diluents. This differentiation is particularly popular in coatings applications, but the designations are useful for almost any solvent application. Active solvents are strong solvents for the particular solute in the application, and are most commonly ketones or esters. Latent solvents function as active solvents in the presence of a strong active solvent. Alcohols exhibit this effect in nitrocellulose and acrylic resin solutions. Diluents, most often hydrocarbons, are nonsolvents for the solute in the application. 

A Practical Approach to Solvent Applications in Coatings and Inks... 

The California Air Resources Board (GARB) established the VOC concept for the delineation of acceptable coatings and application systems (VOC = volatile organic compounds, e.g., a maximum of 3.5 lb of controlled solvent/gal. of wet paint). 

Blistering due to gas formation or gas inclusion Volahle components leading to bhster formahon can become incorporated in the coating during application, or they can result from inclusions of solvents from phase separation. They can also be generated because of cathodic protection or even to a corrosion process if it generates H2. 

Solvents are used to carry dissolved or suspended resin and evaporate from the coating after application. Additives in small amounts are used as mildew inhibitors (cuprous compounds), surface-drying additives (manganese and cobalt naphthanates), and barrier-forming additives to protect the resin from heat and UV degradation. Fillers (talc and mica) decrease the permeability of oxygen and water in the coating. 

Azeotropes. One solvent may form azeotropes with another solvent due to molecular association. This physical principle can be exploited in several ways. The most important in solvent applications is the possibility of reducing the boiling temperature (some azeotropes have lower boiling point) therefore an applied product such as a coating may lose its solvents and dry faster. The formation of such azeotrope also lowers flash point by which it increases hazards in product use. The formation of an azeotrope is frequently used to remove water from a material or a solvent. It affects the results of a distillation since azeotrope formation makes it difficult to obtain pme components from a mixture by distillation. Azeotrope formation can be suppressed by lowering the boiling point (distillation under vacuum). One benefit of azeotropic distillation is the reduction in the heat required to evaporate solvents. 

Dip coating (or tumble coating) is ideal for small, mass-produced articles requiring single coat paint application. Quality of finish is not as high as spray coating and control of film thickness is difficult. Solvents used tend to be relatively simple systems of either medium or slow-evaporating solvents, the exact choice... 

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