Study on the effect of synthetic wax – oxidized wax on the properties of modified alkyd resin waxes

Castor oil, glycerol, phthalic anhydride, Fischer-Tropsch synthetic wax A28 and oxidized paraffin wax were used as raw materials to synthesize oil-soluble alkyd resin waxes. The effects of polyesterization reaction time, the addition of A28 wax and oxidized paraffin on the acid value, penetration and droplet melting point of medium and long oil alkyd resin waxes were investigated respectively. The experimental results showed that the best formula for the preparation of alkyd resin wax was 72.1 g of castor oil, 21.7 g of glycerol, 40.5 g of phthalic anhydride, 17.1 g of A28, and the reaction time of polyesterization was 4 h. The synthesized alkyd waxes had the following values: acid value: 18.96 mg KOH/g, drip melting point: 102 cc, and needle penetration: 13.40 mm.

  After decades of development, the synthesis technology of alkyd resin coating is mature, the raw materials are easy to obtain, and the comprehensive performance of the coating film is good, but it also has obvious shortcomings, such as slow drying of the coating film, low hardness, poor water resistance, air-drying alkyd resin coating is easy to be yellowed by the light, and poor weathering, etc., which is limited in its use, and it needs to be improved by modification to improve its comprehensive performance. Generally, there are physical modification, chemical modification in which the modifier acts as a carboxyl group, chemical modification in which the modifier acts as a hydroxyl group, and chemical modification utilizing the double bond reaction. In this experiment, the method of modification is chemical modification by carboxylation of modifier, and two different oxidized waxes, namely oxidized F-T synthetic wax and oxidized paraffin wax, were used to modify the alkyd resin instead of part of phthalic anhydride, and a new alkyd resin wax was synthesized. The synthesized alkyd resin wax is characterized by good water resistance, high drip melting point and good rust prevention, and it can be used as rust prevention wax for automobile interior cavity, which fills the gap in China.