Alkyd resins processing equipment

Fig. 1 Alkyd resin processing equipment. [Reprinted from Amoco TMA as Primers for Alkyd-Melamine Enamels and Acrylic Lacquers, Tec. Bull. TMA 25a. Amoco Chemical Corp., Chicago, Illinois, 1974.]...

The processing equipment (reaction kettle and blending tank) used for unsaturated polyesters can also be used for manufacturing alkyd resins. 

Figure 2. Equipment for solvent processing of alkyd resins. Courtesy of Hercules Inc. (Wilminton, Del.).

About one-half of the phthalic anhydride production is consumed for the preparation of plasticizers, mostly for the various flexible grades of poly(vinyl chloride). The remainder is roughly split between alkyd resin preparation used for many types of surface coatings, and for polyester resin composites with fiberglass reinforcement, the so-called fiberglass resins used in boats and other sporting equipment as well as for corrosion-resistant vessels and ducts used in chemical processing, some automotive parts, and as a convenient means of field repair of many of these items. 

Regardless of the way fatty acids are incorporated, the main step of alkyd synthesis is the polyesterification. This process is quite similar to the process for saturated polyester resin production, and actually more or less the same equipment can be used (Figure 16.3). The polyesterification of the alkyd raw materials normally proceeds at 240°C with the aid of xylene as a mode of transportation of the water, by forming a binary azeotrope with it. The xylene and water vapors rise through the column on top of the reador and are condensed on top of a separator. The xylene is pumped back into the reador and the water is removed. Because of... 

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