GB1049462A - Production of oil-modified alkyd resins - Google Patents

Abstract

An oil-modified alkyd resin is derived from phthalic anhydride, a polyhydric alcohol and a modifying oil comprising at least 50 wt. per cent of cod liver oil. When the oil length exceeds 45% an a ,b -unsaturated dicarboxylic acid or anhydride is also present; when the oil length is less than 45% a monocarboxylic acid or anhydride is added; between 40 and 50%, however, the additional components are not essential. The polyhydric alcohol may be glycerol, pentaerythritol or trimethylolethane, and may include some diol, e.g. diethylene glycol or propylene glycol. Suitable a ,b -unsaturated acids are fumaric, maleic, citraconic and mesaconic acids, and suitable monocarboxylic acids are benzoic, toluic and t-butylbenzoic acids, or aliphatic acids containing up to 10 C-atoms, e.g. caproic and capric acids. Preferably the cod liver oil or oil mixture is first alcoholysed with the polyhydric alcohol, usually in the presence of a catalyst, e.g. Ca(OH)2, and is then condensed with the rest of the starting materials, including any further polyhydric alcohol required. Usually the amounts used of the a ,b -unsaturated acid, or of the monocarboxylic acid, do not exceed 15% or 20% by weight respectively of the phthalic anhydride. The amounts increase as the oil length departs from the 45% value. The polyhydric alcohol is usually in excess, there preferably being 1.1-1.3 OH groups per carboxyl group in free or anhydride form. The condensation may be performed with reactants fused or in solution, e.g. in xylene, preferably at 200-300 DEG C. The product may have an acid value below 10 or 15, and be soluble in solvent naphtha and xylene. The cod liver oil may be mixed with up to 50 wt. per cent of other marine or vegetable oils, and other dicarboxylic acids or anhydrides may be included, e.g. adipic or sebacic acid. In examples an alkali-refined cod liver oil is heated with glycerol and Ca(OH)2 and is then heated with [1] phthalic anhydride, glycerol and benzoic acid, [2], [3] phthalic anhydride, maleic anhydride and xylene, to give alkyds of oil lengths 33%, 55% and 70% respectively. These are milled with TiO2 in xylene to give paints. The paints from resins [1] and [2] are stove-dried, that fro [3] is airdried, after addition of cobalt and lead naphthenate driers.