Colored powder coating compositions

A process for the preparation of a coloured powder coating composition in a desired colour, characterized by providing powder coating compositions in at least two basic colours, optionally together with an uncoloured powder coating composition, each composition consisting of solid particles and each particle comprising a solid polymeric binder system comprising a film-forming resin, the particles of each of the basic colour compositions also containing at least one colouring agent, comminuting the compositions to a particle size such that substantially all the particles have their largest dimension below 20 microns, and mixing the powder coating compositions in proportions selected to give a coloured powder coating composition which when applied to a substrate and heated to form a continuous coating forms a film of the desired colour, wherein the mixed particles are agglomerated to produce composite particles of a mean particle size of 15 to 75 microns.

A process for the preparation of a coloured powder coating composition in a desired colour, characterized by providing powder coating compositions in at least two basic colours, optionally together with an uncoloured powder coating composition, each composition consisting of solid particles and each particle comprising a solid polymeric binder system comprising a film-forming resin, the particles of each of the basic colour compositions also containing at least one colouring agent, and comminuting the compositions to a particle size such that substantially all the particles have their largest dimension below 10 microns and simultaneously mixing them in proportions selected to give a coloured powder coating composition which when applied to a substrate and heated to form a continuous coating forms a film of the desired colour, wherein the mixed particles are agglomerated to produce composite particles of a mean particle size of 15 to 75 microns.

A process for the preparation of a coloured powder coating composition in a desired colour, characterized by providing powder coating compositions in at least two basic colours and optionally also in uncoloured form, each composition consisting of solid particles and each particle comprising a solid polymeric binder system comprising a film-forming resin, and in the case of each of the basic colour compositions also at least one colouring agent, comminuting the compositions to a particle size such that substantially all the particles have their largest dimension below 20 microns, and mixing and agglomerating the said powder coating compositions by an electrostatic mixing technique in which a powder coating composition in a first basic colour is electrically charged and a powder coating composition in a second basic colour is not so charged or is charged to a different potential and the powders are mixed to form composite particles of mean particle size 25 to 75 microns, which when applied to a substrate and heated to form a continuous coating form a film of the desired colour.

A rocess for the preparation of a coloured powder coating composition in a desired colour, characterized by providing powder coating compositions in at least two basic colours, optionally together with an uncoloured powder coating composition, each composition consisting of solid particles and each particle comprising a solid polymeric binder system comprising a film-forming resin, the particles of each of the basic colour compositions also containing at least one colouring agent, and comminuting the compositions to a particle size such that substantially all the particles have their largest dimension below 20 microns and mixing the compositions in proportions selected to give a coloured powder coating composition which when applied to a substrate and heated to form a continuous coating forms a film of the desired colour.