POLYMER, COMPOSITION AND USE

1 . A solvent assisted dispersion (SAD) process for preparing an aqueous polycondensate dispersion substantially free of solvents, the process comprising the step of:

(a) reacting in the presence of a non-protic solvent a mixture of

(i) one or more polycondensate monomers, polycondensate oligomers and/or polycondensate polymers comprising a plurality of isocyanate-reactive groups; wherein the monomers, oligomers and/or polymers comprises at least 2% by weight (components) of a fully, partially or non-neutralized acid group having a pKa less than 3

(ii) at least one multifunctional isocyanate,

to form a mixture of a first polycondensate resin and the non-protic solvent;

(b) optionally, reacting the first polycondensate from step (a) (also denoted herein as emulsifier polymer) with at least one monomer, oligomer and/or polymer different from component (a) (component (b) also denoted herein as performance polymer) to form a second polycondensate resin;

(c) dispersing the first polycondensate resin from step (a) and/or the second polycondensate resin from step (b) in an aqueous medium to form an aqueous polycondensate dispersion.

(d) removing substantially all of the non-protic solvent from the dispersion from step (c) to form a polycondensate dispersion substantially-free of solvent

and where the acid groups are completely or partially neutralized in step (a), or in step (b) or before dispersing the polycondensate in water.

2 . A process as claimed in claim 1 , where further strong acid components comprising monomers, oligomers and/or polymers (preferably polycondensate monomers, polycondensate oligomers and/or polycondensate polymers) are used in and/or added to the mixture(s) of step (a) and/or (b) in an amount of least 2% by weight (of total components (a) to (b)) such strong acid components have thereon a fully, partially or non-neutralized acid group having a pKa less than 3; and where the further strong acid components are used in and/or after step (a)(i) and/or (b).

3 . A process as claimed in claim 1 , in which the polycondensate comprises a polyamide and/or polyester.

4 . A process as claimed in claim 3 , in which the polycondensate comprises a polyester.

5 . A process as claimed in claim 4 , in which the polyester comprises an alkyd.

6 . A process as claimed in claim 1 , in which the polyester dispersion is chain-extended by using one or more chain extenders.

7 . A process as claimed in claim 1 , in which the first and/or second polycondensate comprises uralkyds that have a number average molecule weight of from 1,000 to 1,000,000 daltons,

8 . A process as claimed in claim 1 , in which the first and/or second polycondensate comprises uralkyds that have a weight average molecule weight of from 1,000 to 1,000,000 daltons,

9 . A process as claimed in claim 1 , in which the first and/or second polycondensates comprise uralkyds that are obtained and/or obtainable from three- or higher functional hydroxyl and/or carboxy functional components.

10 . A process as claimed in claim 1 , in which the product from step (d) has less than 0.1 wt-% of organic solvent by weight of total polycondensate resin (preferably is substantially free of organic solvent).

11 . An aqueous dispersion of a polycondensate uralkyd obtained and/or obtainable by a process as claimed in claim 1 .

12 . An aqueous coating composition comprising a polycondensate uralkyd obtained and/or obtainable by a process as claimed in claim 1 .

13 . An article and/or substrate coated by a composition as claimed in claim 12 .

14 . A method of coating an article and/or substrate comprising the steps of

(I) applying a coating composition as claimed in claim 12 to an article and/or substrate, and

(II) drying the coating thereon to obtain a coated article and/or substrate.