Aqueous dispersions of polyurethane resins based on rosin

A linear or branched polyurethane resin derived from fatty polyester, wherein said polyurethane resin is derived from at least one hydroxylated fatty polyester A), and wherein:

• said polyester A) is the product of reaction of a) an alcohol component with b) an acid component, which acid component b) comprises b1) at least one fatty acid, said fatty acid being chosen from the group consisting of b1.1) at least one oxidizable fatty monoacid and/or polyacid, comprising at least one oxidizable unsaturation, b1.2) at least one non-oxidizable fatty monoacid and/or polyacid, and b1.3) at least one mixture of fatty acids b1.1) and b1.2),
• said component b) further comprising b2) rosin and/or rosin derivatives bearing at least one carboxylic acid function, said rosin and/or derivatives b2) representing from 30% to 85% by weight relative to the total weight of the hydroxylated fatty polyester A)
• optionally, said polyester A) having a zero oil length (0%) or an oil length of between 0 and 60%,
• optionally, said polyester A) having a weight ratio of oxidizable fatty acids (monoacids) b1.1) relative to the overall fatty acids b1.1)+b1.2) of 0 or greater than 0 and up to 1,
• and with said resin being the product of reaction of said polyol polyester A) with:
• B) at least one diol comprising an acid functional group, chosen from the group consisting of carboxylic, sulfonic, phosphonic or phosphinic, said acid functional group optionally being neutralized to salt form with a weak base, and
• C) at least one polyisocyanate, of functionality from 2 to 3.