Powder coating composition

A composition comprising

• a) at least 50 wt. % of TiO2 particles and
• b) at least 10 wt. % of a component which comprises
• b1) at least one epoxy resin having at least one carbon-carbon double bond and/or at least one carbon-carbon triple bond which are not terminal,
• wherein component b1) is obtained by the reaction of an epoxy resin with an unsaturated component (B), which has at least one carbon-carbon double bond and/or at least one carbon-carbon triple bond which are not terminal and at least one functional group selected from the group consisting of amino, hydroxyl, carboxy and anhydride, and the unsaturated component (B) is an unsaturated fatty acid, a dimerized or trimerized unsaturated fatty acid, polyamidoamine based on an unsaturated fatty acid dimer or trimer, tetrahydrophthalic acid, tetrahydrophthalic anhydride, acetylene dicarboxylic acid, butene diol, a functionalized homopolymer of butadiene or a copolymer of a butadiene with a vinyl or allyl compound selected from the group consisting of acrylonitrile, acrylic acid, methacrylic acid, acrylic or methacrylic acid esters, maleic acid and maleic acid anhydride;
• or
• b2) a mixture of
• i) at least one epoxy resin without a carbon-carbon double bond and without a carbon-carbon triple bond and
• ii) at least one unsaturated organic compound (A) wherein compound (A) is selected from a polybutadiene homopolymer having no functional group capable of reacting with an epoxide group, a polybutadiene copolymer having no functional group capable of reacting with an epoxide group, a partly epoxidized polybutadiene, 4,4′-bismaleimidodiphenylmethane and a mixture thereof and does not react with the epoxy resin b2i) and the weight ratio of component i) to ii) ranges from 1000:1 to 10:5;
• or
• b3) any mixture of b1) and b2),
• wherein the weight % is based on the total weight of the composition.