| 摘要 |
Polyester resins having a colour index as measured with a 50% by weight solution on the Gardner Scale of approximately 0,25 to 1,5 are made by reacting the resin-forming reactants at elevated temperature, maintaining the resinforming reactants during the reaction and the resultant resin prior to cooling in contact with silica. In the examples, polyesters are made from phthalic anhydride and :- (1) glycerine and soya oil, linseed oil or copra oil, (2) glycerine, (3) glycerine, linseed oil and maleic anhydride and (4) maleic anhydride and ethylene glycol in the presence of titanium dioxide. The alkyd resins may also be modified by rosin, natural resins, phenol-formaldehyde resins, urea-formaldehyde resins, polyisocyanates, polyurethanes, rubber or vinyl resins.ALSO:<PICT:0859710/III/1> An apparatus for making polyester resins comprising a reactor 1 equipped with electrical heaters 18, agitator 5 and facilities for the introduction of the reactants and for the removal of the product, is characterized in that the reactor and any ancillary equipment which is in contact with the reactants or with the resin prior to cooling have walls comprising fused silica or quartz glass to ensure the production of a resin which is clear and resistant to discoloration. |
