| 摘要 |
Polyesters are obtained by condensing a polycarboxylic acid and a polyhydric alcohol with a branched aliphatic monocarboxylic acid having the acid group attached directly to a -CH2- group. Suitable acids of the latter type are obtained by oxidation of the "ketoaldehydes" obtained by hydroformylation of an olefine, e.g. a mixture of 3- and 5-methyl-hexanoic acid with a small amount of 2,4-dimethylpentanoic acid derived in this way from 2-methyl-1-pentene. Other suitable acids or mixtures may be derived from propylene trimers and tetramers and co-dimers of propylene and butylene. In examples these are condensed with phthalic anhydride and with ethylene glycol, glycerol, pentaerythritol, and trimethylolpropane, or mixtures of these, to give polyesters, benzoic acid also being added in Example 5. These polyesters may be mixed with aminoplasts, e.g. butylated MF or VF resins, or with phenoplast resins, and with a pigment, e.g. TiO2 to give enamels. The components of the polyester may be condensed simultaneously, or a part of the monacid may be precondensed with the polyol, or the bulk of the monacid may be added after a part of it has been condensed with the polycarboxylic acid and the polyol.ALSO:Thin steel plates are coated with an enamel composition comprising an aminoplast resin, a polyester derived from a polycarboxylic acid, a polyol and a branched aliphatic moncarboxylic acid containing a -CH2COOH group, and a pigment. Used in the Examples are butylated urea- or melamine-formaldehyde resins, TiO2 and polyesters derived from phthalic anhydride, a polyol, and acids obtained by p formylation and oxidation of 2-methyl-1-pentene, propylene trimer or tetramer, propylene/butylene codimer, and optionally benzoic acid. |
