EPOXY FUNCTIONAL POLYESTER RESINS HAVING AN INCREASED MOLECULAR WEIGHT, PROCESS FOR THEIR PREPARATION, AND OUTDOOR DURABLE COATING COMPOSITIONS COMPRISING THEM

摘要

Epoxy functional polyester resins (I), which are storage stable at temperatures up to 40 DEG C and have a Tg of more than 40 DEG C, and which are obtainable by a process, comprising the reaction of an epoxy functional polyester resin (II) obtainable by the reaction of epihalohydrin in the presence of a base with carboxyl functional polyester resins (III) obtainable by reacting: (a) at least one aromatic or cycloaliphatic dicarboxylic acid compound A comprising two aromatic- or secondary aliphatic carboxyl groups or the anhydride thereof; (b) at least one diol compound B comprising two aliphatic hydroxyl groups, which may independently be a primary or a secondary hydroxyl group; and optionally (c) compound C1 comprising one monofunctional primary- or secondary hydroxyl group and/or at least one compound C2 comprising one primary- or secondary hydroxyl group and one tertiary aliphatic carboxyl group; and optionally (d) a dihydroxymonocarboxylic acid compound D comprising a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which may each independently be primary or secondary hydroxyl; and optionally (e) a trihydroxyalkane (E1) or tetrahydroxyalkane (E2), the molar ratio of compounds A:B:C1:C2:D:E1:E2 being X+Y+1:X:M:N:Y:Z:Q wherein M+N is in the range of from 0 to 2, X ranges from 2 to 8 and Y ranges from 0 to 8, Z ranges from 0 to 2 and Q ranges from 0 to 2 at a temperature of from 100 to 220 DEG C, until essentially all the non-tertiary carboxyl groups as initially present in the reaction mixture have been reacted, having a WPE in the range of from 250 to 800, with a carboxy functional polyester resin derived from the herein before mentioned component (a) and (b) or with a component (a) alone, in the presence of a catalyst, and outdoor durable coating compositions comprising them.