Alkyd resins definition

Alkyd resins have been the workhorse for the coatings industry over the last half century. The term alkyd was coined to define the reaction product of polyhydric alcohols and polybasic acids, in other words, polyesters. However, its definition has been narrowed to include only those polyesters containing monobasic acids, usually long-chain fatty acids. Thus thermoplastic polyesters typified by polyethylene terephthalate (PET) used in synthetic fibers, films, and plastics and unsaturated polyesters typified by the condensation product of glycols and unsaturated dibasic acids (which are widely used in conjunction with vinylic monomers in making sheet molding compounds or other thermosetting molded plastics) are not considered as part of the alkyd family and are beyond the scope of the present discussion. 

Alkyd resins have been defined as the reaction product of a polybasic acid and a polyhydric alcohol. This definition Includes polyester resins of which alkyds are a particular type. The specific definition that has gained wide acceptance is that alkyds are polyesters modified with monobasic fatty acids. In recent years, the term nonoil or oil-free alkyd has come into use to describe polyesters formed by the reaction of polybasic acids with polyhydric alcohols in non-stoichlometric amounts. These products are best described as functional saturated polyesters containing unreacted OH and/or COOH groups, and they are finding rapidly increasing uses in organic coatings. 

Beaulight SSS. See Disodium lauryl sulfosuccinate Beau-Ron 800. See Boron Beaverwhite 200. See Talc Beckacite 4900. See Rosin Beckopox EP116] Beckopox VEP 2380w/58WA. See Epoxy resin Beckosol 10-560. See Alkyd resin Bectron EK. See Epoxy resin Beechwood creosote CAS 8021-39-4 Synonyms Wood creosote Definition Mixt. of phenols (chiefly guaiacol, creosol, p-cresol)... 

The term modified alkyd, which formerly was used to describe these products, now is associated with chemical modifications that are carried out during alkyd preparation, and that incorporate chemical agents of types other than those included in the definition. For example, the term rosin-based alkyd resins or rosin-modified alkyd refers to alkyd resins in which all or a portion of the monobasic fatty acid is replaced by rosin. Unmodified alkyd resins are polyester products composed of polyhydric alcohol, polybasic acid, and monobasic fatty acid. When no fatty acids are used, or when they are completely replaced by other types of acid, the products can be considered as oil-free alkyds. 

Secant Modulus se- kant ma-jo-bs n The ratio of stress to corresponding strain at any specific point on a stress-strain curve. It is expressed in force per unit area, MPa or kpsi. This definition of modulus is useful for many plastics whose stress-strain relationships are nonlinear even at very low strains, exhibiting little or no Hooke s-law range. (Shah V (1998) Handbook of plastics testing technology. Wiley, New York) sec-Butyl Acetate sek byii-Ul a-so- tat] n (2-butyl acetate) CH3COOCH(CH3)C2H5. A solvent for nitrocellulose, ethyl cellulose, PVC, acrylics, polystyrene, phenolics and alkyd resins. 

Very little is known about the structure of the cured polyester resin. The products definitely belong in the thermoset class. There is some correlation between maximum physical properties a nd a molar ratio of 1 1 between double bonds in the alkyd and monomer. However, this is not critical and simple cross-linking does not tell the full story. The styrene monomer can be present in twice the molar amount needed, and yet complete copolymerization takes place without apparent formation of styrene polymer. 

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