GB969896A - Process and apparatus for preparing polyester resins and products resulting therefrom - Google Patents

Abstract

<PICT:0969896/C3/1> Alkyd resins are prepared at least partially or are after-processed in an inert organic solvent in an amount of 30-70% of the alkyd or its components under superatmospheric pressure whereby resins having a smaller amount of low and high molecular weight components are produced. The process may be effected (a) by reacting a mixture of a polycarboxylic acid, a polyhydric alcohol and a fatty acid, at least the latter part of the reaction being effected in the presence of the solvent with reflux of solvent and removal of water; (b) effecting an alcoholysis reaction between a triglyceride oil and a polyhydric alcohol under conventional conditions, then adding the balance of the alkyd formulation and the inert solvent and proceeding as above; (c) heating a preformed alkyd in the presence of the solvent with little or no change in acid number and removal of any water of reaction. Specified are:-polycarboxylic acids-phthalic, isophthalic, maleic, fumaric, adipic, sebacic, dimer and trimellitic acids; polyhydric alcohols-ethylene glycol, propylene glycol, glycerol, pentaerythritol, dipentaerythritol, trimethylol propane, trimethylol ethane and sorbitol; monocarboxylic acids-various vegetable, marine and animal oils and their fatty acids, also pelargonic, benzoic, p-tertiary butyl benzoic and cyclohexane carboxylic acid and resin; solvents-aliphatic, cycloaliphatic and aromatic hydrocarbons and chlorinated aliphatic and aromatic hydrocarbons boiling at 66 DEG -215 DEG C. The resins may be made in an apparatus comprising an autoclave 10 connected to a condenser 12, a condensate and water trap 14 and a solvent return pump 19. Various valves in the apparatus are so arranged that the autoclave 10 may be operated under increased pressure and in this case a valve 44 is automatically adjusted to establish system equilibrium between the high pressure reacted by the reaction and solvent and the normal pressure in the condenser and trap. Also the pump 19 operates to draw the solvent condensate from the trap 14 and force it back into the reactor 10. Examples describe the preparation of alkyds from phthalic anhydride, soya fatty acids and pentaerythritol together with glycerol or ethylene glycol. The resin may be compounded with the usual metallic driers and with butylated melamine-formaldehyde resins.