Powder coating compositions containing functional polysiloxanes

A powder coating composition comprising a solid particulate film-forming mixture of the following:

• (a) a polymer selected from the group consisting of acrylic, polyester, polyurethane and polyether polymers, and mixtures thereof, having reactive functional groups selected from the group consisting of hydroxyl groups, carbamate groups, epoxy groups, and mixtures thereof;
• (b) a curing agent having functional groups reactive with the functional groups of the polymer (a);
• and
• (c) an organic polysiloxane having reactive functional groups, said polysiloxane having the following general formula:
• where m is at least 1;
• m′ is 0 to 50;
• n is 0 to 50;
• the R groups are monovalent hydrocarbon groups connected to the silicon atoms;
• Ra has the following structure:
• R1—O—X
• wherein R1 is alkylene, oxyalkylene or alkylene aryl;
• and X is a moiety containing a functional group reactive with the functional groups of the polymer (a) and/or the curing agent (b).