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Paint Driers

(Metal Carboxylates)

 

Paint Driers (metal carboxylates) serve as catalysts to promote curing and allow for drying in alkyd paints and coatings. They are produced by reactions of metallic salts with organic or synthetic acids, dissolved in a hydrocarbon solvent, to form a metal soap. Metal soaps are lipophilic so they integrate well with the alkyd hydrocarbon matrix. Transition metal driers are categorized into three groups (Primary, Through/Secondary, and Auxillary) and various combinations of these groups can yield significantly reduced drying times and improved appearance.

Other uses for metal carboxylates include printing inks, lubricants, and fuels.

 

Naphthenates

Produced from highly refined naphthenic acid, a bicyclic aromatic compound. These carboxylate types have outstanding light color, excellent stability, minimum odor and low viscosity. Naphthenates are particularly favored when lower water solubility and high affinity for organic media is necessary. However, there is some concern about the environmental effects of napthenates, so we offer synthetic metal carboxylate alternatives.

Octoates

Produced from synthetic 2-ethylhexanoic acid. Synthetic acids are used in place of naturally occurring acids as they offer low odor, enable higher metal contents and consistent quality. Compared to Naphthenates, these carboxylates types offer better color, lower odor, safer use, and fairly greater efficiency.

Mechanism

Driers are utilized exclusively in unsaturated aliphatic systems to catalyse crosslink formation. Alkyd resins are synthesized from polyols, polyacids, and naturally occurring fatty acids and oils; the oil "tails" must be covalently crosslinked in order for the resin layer to dry completely. This happens through a process called autoxidation, and proceeds via a number of peroxy radical intermediates. Although most alkyd resins will eventually dry under ambient conditions, the presence of a transition metal catalyst helps to push the intermediate equilibrium in favor of the radical intermediate, thus reducing drying time from several days to a matter of hours.

Metals Offered

Driers can be catagorized at primary, through (secondary), or auxillary. A primary drier is required for all formulations, but they are only active at the surface of the resin where oxygen concentration is greatest. To penetrate the entire layer of coating, a through or auxillary drier must be mixed in.

Primary Secondary Auxillary
Cobalt - 6%, 10%, 12% Zirconium - 12%, 18%, 24% Calcium - 4%, 6%, 10%
Manganese - 6%, 9%, 10%, 12% Strontium - 18% Potassium - 15%
  Lead - 24%, 36% Zinc - 8%, 16%, 22%
    Lithium - 2%