Composition suitable for a powder coating composition comprising at least one resin and at least one dispersant

1. Process for the preparation of a powder coating composition having a glass transition temperature (Tg) at or above 20° C. and comprising (i) a resin having a Tg above 35° C. and functional groups through which the resin can react with a crosslinker, (ii) a crosslinker having functional groups which are able to react with the functional groups of the resin, (iii) a pigment powder, and (iv) a dispersant for dispersing the pigment powder in the powder coating composition, wherein the process comprises the steps of:

(a) preparing the resin in a reactor;

(b) adding the dispersant to the resin when the resin is in a liquid state at a temperature above the glass transition temperature (Tg) of the resin and at or below 270° C. just before the resin leaves the reactor or while the resin leaves the reactor in an amount of at least 0.01 to at most 10 w/w% based on the weight of dispersant in the resin to obtain a mixture of the resin and the dispersant;

(c) solidifying the mixture of step (b);

(d) mixing the pigment powder in an amount of more than 40 w/w% based on the weight of the powder coating composition and the crosslinker with the solidified mixture of step (c) to obtain a pigment-containing mixture;

(e) homogenizing the pigment-containing mixture of step (d) to obtain a homogenized mixture; and

(f) milling and sieving the homogenized mixture to obtain the powder coating composition.

2. Process according to claim 1 , wherein the resin is selected from the group consisting of polyester resin, acrylic resin, polyesteramide, epoxy resin and combinations thereof.

3. Process according to claim 1 , wherein the Tg of the resin is above 45° C.

4. Process for the preparation of a coated substrate comprising the steps of:

preparing a powder coating composition according to claim 1 ; and

fully or partially coating a substrate with the powder coating composition.

5. Process according to claim 4 , further comprising the step of curing the powder coating composition.

6. Process according to claim 1 , wherein step (d) comprises mixing the pigment powder with the solidified mixture of step (c) in an amount of more than 50 w/w% based on the weight of the powder coating composition.

7. Process according to claim 1 , wherein step (d) comprises mixing the pigment powder with the solidified mixture of step (c) in an amount between 50 and 85 w/w% based on the weight of the powder coating composition.