Modified natural-resin acid-aldehyde adducts

A resin consisting of one or more units of compounds of each of groups A, B, C, and D;

• and optionally, one or more compounds of each of groups E, F, and G, wherein:
• the compounds of group A are selected from the group consisting of natural resins and natural resin acids;
• the compounds of the group B are selected from the group consisting of aldehydes and aldehyde acetals;
• the compounds of the group C are selected from the group consisting of alcohols having at least two hydroxyl groups;
• the compounds of the group D are selected from the group consisting of metal salts;
• the compounds of the group E are selected from the group consisting of .alpha.,.beta.-ethylenically unsaturated carboxylic acids and their anhydrides;
• the compounds of the group F are selected from the group consisting of fatty acids and fatty acid esters;
• and
• the compounds of the group G are selected from the group consisting of ethylenically unsaturated hydrocarbon resins.

A process for the preparation of a resin which comprises:

• (i) reacting one or more compounds of each of the groups A and B, wherein:
• the compounds of group A are selected from the group consisting of natural resins and natural resin acids;
• the compounds of the group B are selected from the group consisting of aldehydes and aldehyde acetals;
• and
• (ii) subsequently reacting the product obtained in (i) with one or more compounds of each of the groups C and D and optionally one or more compounds of each of groups E, F and G, wherein the reaction of subsection (ii) is carried out at a temperature of from 100.degree. to 300.degree. C. with the elimination of water, and wherein:
• the compounds of the group C are selected from the group consisting of alcohols having at least two hydroxyl groups;
• the compounds of the group D are selected from the group consisting of metal salts;
• the compounds of the group E are selected from the group consisting of .alpha.,.beta.-ethylenically unsaturated carboxylic acids and their anhydrides;
• the compounds of the group F are selected from the group consisting of fatty acids and fatty acid esters;
• and
• the compounds of the group G are selected from the group consisting of ethylenically unsaturated hydrocarbon resins, and wherein the resin contains substantially no phenol or phenol-aldehyde condensation products.