Synthesis and Improvement of Activity of Cobalt Organic Salts as Drier

Organic salts of cobalt were synthesized in the presence of amine, ethanol, and ethyl methyl ketoxime and were used as drier for alkyd resin. Considering the drying time of alkyd resin containing synthesized compound showed that amines, as electron releasing groups (ERG), increased the oxidizing activity of drier and shortened drying time about an hour, whereas ethyl methyl ketoxime delayed the drying of resin 2？hours. Two methods of synthesis, including solution and precipitation processes of synthesis, were compared in terms of convenience, cost, and environmental aspects. 1. Introduction Metal alkanoates, metallic soaps, possessing interesting structural, and magnetic and photochemical properties have variety of applications in important areas such as material science, catalysis, and paint industries [1]. Among them, metal 2-ethyl hexanoates and their analogues are also used as fungicide, lubricating agents, plastic stabilizers, waterproof agents, and fuel additives [2]. As a catalyst, they are used in Ziegler nickel catalyst [3], stereoselective Diels-Alder reactions [4], and especially for oxidation and oligomerization of unsaturated chain of alkyd resin in paint industries [5]. Driers are a group of metallic soaps or salts containing either alkaline-earth metals or heavy metals. Common organic acids used are linolenic acid, rosin acids, tall fatty acid, naphthenic acid, and 2-ethyl hexanoic acid (2-EHA) [6]. Driers are added to air-drying coating systems to catalyze the oxidative cross-linking reactions [7]. Most of drier metals are in the oxidation state of +2 and usually dissolved in hydrocarbon solvents such as mineral spirit (clear liquid including a mixture of typically >65% C10 or higher of aliphatic and aromatic hydrocarbons) or aliphatic solvents. Driers are often divided into two categories: primary and secondary driers. Primary (catalytic, surface, or oxidative) driers promote rapid surface drying [7]. Cobalt, manganese, vanadium, cerium, and iron-based catalysts belong to this group. Several physical and chemical experiments have been done to understand the nature of paint films during drying process [8]. Generally, evaporation of volatile materials, absorption of oxygen from the air, and formation of larger molecules from smaller ones take place to form dried film of paint [9]. Driers promote oxygen uptake, peroxide formation, and decomposition at ambient temperature. Free radicals produced in the process lead to the formation of polymer-polymer cross-links. Drier accelerators such as 2,2-bipyridine (bpy) and 1,10-phenantroline are