Alkyd

Unsaturated polyesters in which the alkene double bond resides in a fatty acid component such as oleic (IX) and linoleic (X) acids are referred to as alkyds or alkyd resins (Sec. 2-12a). 

Alkyds are crosslinked via oxidation by atmospheric oxygen [Marshall et al., 1987 Solomon, 1967]. The process is usually referred to as drying or air-drying. Varnishes and other surface coatings based on these polymers are crosslinked by standing in air. 

The crosslinking process is different depending on whether the unsaturation is an unconjugated double bond as in oleic acid or a conjugated double bond as in linoleic acid. Unconjugated double bonds undergo crosslinking by the initial formation of an allylic hydroperoxide 

Crosslinking of alkyds containing conjugated double bonds results in more carbon-carbon bonds in the crosslinks than in the alkyds containing unconjugated double bonds. The crosslinking mechanism involves the formation and decomposition of cyclic peroxides, to yield radicals that initiate crosslinking by 1,4-polymerization of the polymer molecules. 

In commercial use since 1927 [18], alkyd resins are among the most widely used anticorrosion coatings. They are one-component air-curing paints and, therefore, are fairly easy to use. Alkyds are relatively inexpensive. Alkyds can be formulated into both solvent-borne and waterborne coatings. 

In addition, it should be noted that alkyd resins generally exhibit poor barrier properties against moisture vapor. Choosing an effective anticorrosion pigment is therefore important for this class of coating [1]. 

Alkyd thermoset compounds are based on unsaturated polyester resins, which are combined with cross-linking monomers, catalysts, reinforcements, lubricants, and fillers. They are similar to TS polyesters, but have lower levels of monomers. They are part of the group that includes the bulk-molding compounds (BMCs) and sheet-molding compounds (SMCs). Their fast molding cycles at low pressure make them easier to process than other TSs by vacuum, compression, transfer, or injection molding. 

Alkyd compounds are furnished in granular form, extruded rope and logs, as a BMC, and in puttylike grades. Except for the latter, which can be used for encapsulation, these compounds contain fibrous reinforcement. Because the fillers are opaque and the resins amber, translucent colors in alkyds are not possible. However, opaque light shades can be produced in most colors. 

Alkyds dimensional stability in regard to their mechanical and electrical properties are retained over wide temperature ranges. Alkyd parts will resist weak acids, organic solvents, and hydrocarbons such as alcohol and the fatty acids, but they are attacked by alkalis. 

Halogen- or phosphorus-bearing alkyds with antimony trioxide added will provide improved flame resistance, and other flame-resistant compounds are available that do not contain halogenated additives. Many grades are UL rated at 94V-0 in sections under 1/16 in. Their flammability ratings, which depend on their specific formulations, can vary from 94HB to V-0, and may vary in section thickness. 

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Much of the benzoic acid produced is converted to sodium benzoate, which is used as a food preservative (as is the acid) and a corrosion inhibi tor. Other important uses of the acid are in the manufacture of alkyd resins, plasticizers, caprolactam, dyestuffs and pharmaceuticals. 

Methyl-2-pentanoi b.p. 132 C, a solvent for nitrocellulose, urea-formaldehyde and alkyd resins. It is also used in ore flotation. 

The polycondensation of di-isocyanates with polyhydric alcohols gives a wide range of polyurethanes which are used as artificial rubbers and light-weight foams, and have other important properties. Isocyanates are also used as modifiers in alkyd resins. ... 

Most naphthalene produced is utilized in the manufacture of phthalic anhydride, for plasticizers, alkyd resins and polyesters. It is also used in the manufacture of 2-naphlhol and insecticides. Naphthalene derivatives are of importance, particularly as dyestufT intermediates. 

Used as fibres, particularly in textiles and film. Many other polyester polymers are of importance, e.g. unsaturated polyester resins from phthalic anhydride, propylene glycol and maleic anhydride used with reinforcement in boats, cars, etc. (alkyd resins). U.S. production 1983 1-7 megatonnes. 

HOaQCHjlfiCOiH, CSH14O4. Important dicarboxylic acid obtained by oxidizing ricino-leic acid (from castor oil) also obtained by oxidation of cyclo-octene or cyclo-octadiene formerly obtained from cork. Used in the formation of alkyd resins and polyamides. Esters are used as plasticizers and heavy duty lubricants and oils. 

Polyesters from polybasic acids and polyhydric alcohols. Alkyd resins. The condensation of polyhydric alcohols and polybasic acids or anhydrides leads to polj esters known as alkyd resins. The most common member of the group is a glycerol - phthahc acid polymer, and this has led to the term glyptal resins being frequently apphed to the whole group. 

The properties of the polymers may be modified by mixing abphatic acids or anhydrides with the phthalic anhydride. Many alkyd resins find application in the paint industry. 

Alkyds are formulated from polyester resins, cross-linking monomers, and fillers of mineral or glass. The unsaturated polyester resins used for thermosetting alkyds are the reaction products of polyfunctional organic alcohols (glycols) and dibasic organic acids. 

Key properties of alkyds are dimensional stability, colorability, and arc track resistance. Chemical resistance is generally poor. 

Properties Poly(methyl methacrylate) Cast sheet Impact- modified Heat- resistant Alkyd, molded Acrylic poly(vinyl chloride) alloy ... 

Aromatic polyester Unsaturated polyester Alkyd molding compounds ... 

Alkoxysilanes Alkyd coatings Alkyd paints Alkyd resins... 

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