Solvents in paints

Composition of Paint-Solvent Mixtures. The composition of a paint-solvent mixture is governed by the application conditions, drying temperature, and drying time of the paint. The solvent mixture in a paint that undergoes physical drying at room temperature contains ca. 45% low boilers, ca. 45% medium boilers, and ca. 10% high boilers. 

The nature of the solvents in the mixture also depends on the type of binder. In order to obtain rapid drying combined with low solvent retention, the solvent mixture should be formulated so that its solubility and hydrogen-bonding parameters lie at the boundary of the binder solubility range. On the other hand, the parameters of the solvent mixture should be similar to those of the binder to ensure satisfactory 

The volatility and dissolution properties of the solvent mixture should be adjusted [14.187] so that its parameters move from the solubility boundary to the solubility center of the binder during evaporation. It must, however, be borne in mind that the solids concentration increases during evaporation of the solvent and that the paint temperature increases or decreases, thus altering the solubility range of the binders. Numerous studies have been published on the evaporation of solvent mixtures from paint films [14.188]. 

The viscosity of a paint is reduced on raising the temperature according to the Arrhenius equation. 

Paints have widely differing viscosities that depend on their application conditions low-viscosity paints are processed by dipping and spraying methods, while high-viscosity paints are used in casting, rolling, and hot-spraying methods. The correct choice of solvents serves to optimize the paint properties [14.200], [14.201]. 

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The main uses of toluene are as a solvent in paints, rubber, and plastic cements and as a feedstock in the manufacture of organic chemicals, explosives, detergents, and polyurethane foams. Xylenes (which exist as three isomers) are used in the manufacture of DMT, alkyd resins, and plasticizers. Naphthalene is mainly used in the manufacture of dyes, pharmaceuticals, insect repellents, and phthalic anhydride (used in the manufacture of alkyd resins, plasticizers, and polyester). 

The type of solvent used depends on the binder. There is normally more than one type of solvent in paint, particularly for spray application. Highly volatile solvents are needed to reduce the viscosity during atomization and then disperse as quickly as possible, but lower volatile solvents are necessary to remain momentarily to ensure that there is sufficient flow to form a continuous film. 

Ketones are characterized by carbonyl groups anywhere in a chain except at the end, and the carbonyl carbon is bonded only to other carbons. Ketones are particularly important as solvents in paints, particularly methyl ethyl ketone and methyl isobutyl ketone. Most have a penetrating odor and are highly flammable. 

Gas chromatography is widely applied in the paint and varnish industry for analysis of solvents, oils, resins, plasticisers and polymers (by pyrolysis techniques). GC-TCD and GC-FTD on capillary and packed columns are used for direct determination of solvents in paints [143,144], DIN ISO 11890-2 describes an officially approved GC test procedure for solvents in paints and varnishes (VOCs 0.1-15%). 

Xylene is used as a solvent in paint. A certain painting operation evaporates an estimated 3 gal of xylene in an 8-hr shift. The ventilation quality is rated as average. Determine the quantity of dilution ventilation air required to maintain the xylene concentration below 100 ppm, the TLV-TWA. 

Now, IPA is used primarily as a coating and processing solvent in paints, electronics applications, synthetic resins, personal care products, and cosmetics. It is also used as a chemical intermediate for isopropyl esters, isopropyl amines, methyl isobutyl ketone, diisobutyl ketone, and hydrogen peroxide production.-... 

Methanol is a colourless liquid and boils at 337 K. It is highly poisonous in nature. Ingestion of even small quantities of methanol can cause blindness and large quantities causes even death. Methanol is used as a solvent in paints, varnishes and chiefly for making formaldehyde. 

Ethanol is a colourless liquid with boiling point 351 K. It is used as a solvent in paint Industry and in the preparation of a number of carbon compounds. The commercial alcohol is made unfit for drinking by mixing in it some copper sulphate (to give it a colour) and p n idine (a foul smelling liquid). It is known as denaturation of alcohol. 

The use of kerosene as a solvent in paints and insecticides increases the likelihood of exposure by painters, particularly when spray applicators are used (Fidler et al. 1987), and in exterminators. Use of a respirator, alternate application methods (brush or roller), and increased ventilation can all reduce worker exposure to the solvent vapor. 

Dichloromethane is used principally as a solvent, in paint removers, degreasers and aerosol products, and in the manufacture of foam polymers. Widespread exposure occurs during the production and industrial use of dichloromethane and during the use of a variety of consumer products containing dichloromethane. Substantial losses to the environment lead to ubiquitous low-level exposures from ambient air and water. 

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. 

Many of these so-called halogenoalkanes are used as solvents. For example, dichloromethane is used as a solvent in paint stripper (Figure 14.6). 

Figure 14.6 Dichloromethane is used as a solvent in paint stripper.

VM P Naphtha- -Varnish Makers and Painters Naphtha term for a naphtha commonly used as a solvent in paints and varnishes. 

All paints are solutions. Solutions have two ingredients, a solute and a solvent. In paint, pigment is the solute and binder is the solvent. 

MW 112.56 CAS [108-90-7] used in heat transfer medium and as a solvent in paint colorless liquid with a faint almond odor, boils at 131°C solidifies at -55°C density 1.1 g/rnL at 20°C insoluble in water, miscible with organic solvents. 

Exposure of soldiers to Pyridostigmine Bromide (PB), a toxic yellow liquid commonly used as a solvent in paints and medicines, NAPS tablets and vaccinations both in large numbers and in various types have now been recognised and acknowledged by both the British and the American governments. Additionally, in the theatre of operations,... 

Use in glycerol-based surfactants for degreasing, perfume and printing inks and as a non-volatile reactive solvent in paints... 

Refinery or tank farm spills Cleaning reactors and storage tanks Carrier solvent in paints, stains and anti-corrosion coverings... 

Hydrocarbon solvents are the most commonly used solvents in paints to carry the pigment and binder. They are divided into three groups aliphatic, naphthenic, and aromatic. The preferred type of solvent is an odorless aliphatic hydrocarbon (mineral spirits), which can be used in all areas including home. However, mineral spirits do not dissolve all binder resins. Aromatic solvents provide stronger solvency, but with a greater odor. The most common are toluene, xylene, and naphthas. 

D-Limonene is also synthetically produced, including as a by-product in the manufacture of terpineol. It is used in flavors and fragrances, as a solvent (e.g., as a natural replacement for petroleum-based solvents in paints and cleaning products), and for numerous other commercial uses. o-Limonene is also used as an inert ingredient in pesticides, and is used in resin manufacture. 

Methylene chloride has been used as a solvent in paint stripping formulations as a propellant in aerosols as a process solvent in the manufacture of drugs, pharmaceuticals, and film coatings as a metal... 

Xylenes are used as thinners solvents in paints, inks, rubbers, gums, resins, adhesives, and lacquers paint removers and as intermediates in the production of plasticizer (phthalic acid and anhydride) and polyester fibers. They are also used extensively as intermediates in the manufacture of perfumes, dyes, insecticides, and pharmaceuticals. The annual production of mixed xylenes varies between 6 and 12 billion pounds. 

The quantities of solvents in paints vary with desired characteristics (e.g., drying time desired) and application (building interiors, automotive surfaces, and architectural applications). Other solvents, including chlorinated hydrocarbons and terpenes, for example, are also formulated into paints. Virtually all solvent-based paints contain mixtures of lipophiles and hydrophiles. The exposures of painters to low levels of solvents (sufficiently low enough so that they do not experience acute symptoms at the time of exposure and below the TLVs for the individual solvent molecules) enables one to ascribe neurotoxicological reactions to low level mixture exposures. 

Use Organic synthesis, latent solvent in paints and lacquers, intermediate for amino coating resins, substitute for n-butanol. Paint removers, fluorometric... 

About two-thirds of the isopropanol produced is used as an intermediate to form other chemicals, mostly for acetone production. The remainder is used as a solvent in paints and coatings and other chemical processes. 

Solvents in paint or a coating serve multiple purposes. These include solubilization of resins and other ingredients, wetting, viscosity reduction, adhesion promotion, and gloss enhancement. Initially, the resin or polymer is dissolved in the solvent to form a continuous phase. 

Butoxyethanol acetate can pass into air from water and soil. It is directly released to the atmosphere by evaporation while it is being used as a solvent in paints, lacquers, thinners, inks, ink and spot removers, and resins. 2-Butoxyethanol acetate probably exists almost entirely as a vapor in outdoor air. It can be removed from the air by precipitation because it is moderately soluble in water. In air, 2-butoxyethanol acetate may also break down to other compounds... 

Ethanol is the most common toxic substance involved in medical-legal cases. It is frequently a contributory factor in accidents. Methanol content is controlled in drinking water and fermentation media. It is also a widely used solvent in paints. The determination of other aliphatic alcohols is of minor importance. 

Table I. Estimated Consumption of Solvents in Paints and Coatings...

Halso . [OxyChem] Monochloro-tduene extender, diluent, or substitute for other organic solvents for dye carrier, fuel oil additive, sludge solvent, in paint thinnas and strippers, metal parts cleaners, adhesives, t c. applies. 

USE Denaturant for ethanol, mfg flotation agents, flavors, perfumes as solvent in paint removers. Octane booster in gasoline. 

USE As solvent in paint and lacquer industry in perfuming of soaps and detergents in technical odor masking. 

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