| 摘要 |
In the compositions described, the binder consists at least in part of a water-dilutable and at least partly epoxy-resin modified polyester. Said compositions are characterized in that the said polyester is produced (a) by synthesizing a polyester from (a1) at least one polycarboxylic acid containing at least three carboxyl groups or a reactive derivative of this acid and/or (a2) at least one polyol containing at least one carboxyl group and (a3) at least one polycarboxylic acid containing two carboxyl groups or from a reactive derivative of this acid and (a4) at least one polyol, - at least 10 moles %, preferably 30-70 moles %, of the components employed (a1, a2, a3), a4) (related to (a1) + (a2) + (a3) + (a4) = 100 moles %) comprising at least 6 carbon atoms; this polyester has a mean molecular weight (numerical mean) of less than 2000, preferably between 500 and 1500, an acidity index of between 35 and 240, preferably between 50 and 120, an OH index of between 56 and 320, preferably between 80 and 200, and all the components (a1) and (a3) are condensed by means of at least two carboxyl groups. (B) The polyester thus obtained is made to react with 0.3 to 1.5, preferably 0.5 to 1.0 equivalent per molecule of polyester of an epoxy-resin, having an equivalent epoxy weight of between 170 and 1000, preferably between 170 and 500, based on a biphenol, preferably biphenol A, and/or with a derivative of this epoxy-resin, containing at least one epoxy group per molecule, in reaction conditions where essentially only carboxyl groups react with epoxy groups, in order to produce a polyester modified by an epoxy resin, which, after neutralization of at least a part of the free carboxyl groups, is in a water-dilutable form. |
