Radiation curable powder compositions

Radiation curable powder composition according to any of the preceding claims, wherein the (meth)acryloyl group containing amorphous polyester is obtainable from the reaction of a di-isocyanate with an hydroxyalkyl(meth)acrylate and a hydroxyl group containing polyester or from the reaction of glycidyl(meth)acrylate with a polyester containing carboxyl groups.

Radiation curable powder composition according to any of the preceding claims, wherein the (meth)acryloyl group containing amorphous polyester has a degree of unsaturation of 0.15 to 1.80, preferably of 0.35 to 1.25 milliequivalents of double bounds per gram of polyester, a number average molecular weight from 1,100 to 16,000, preferably between 1,300 and 8,500, measured by gel permeation chromatography (GPC), a glass transition temperature determined by differential scanning calorimetry (DSC) according to ASTM D3418-82 from 35 to 80° C. and a viscosity in the molten state measured at 200° C. with a cone/plate viscosimeter according to ASTM D4287-88 from 1 to 20,000 mPa.s.

Radiation curable powder composition according to any of the preceding claims, wherein the (meth)acryloyl group containing polyphenoxy resin is the reaction product of (meth)acrylic acid with a glycidyl group containing polyphenoxy resin.

Radiation curable powder composition according to any of the preceding claims, wherein the (meth)acryloyl group containing polyphenoxy resin has a degree of unsaturation of 0.5 to 6.0, preferably 0.5 to 4.5 milliequivalents of double bounds per gram of resin, a number average molecular weight from 500 to 5,000, preferably between 650 and 3,500, measured by gel permeation chromatography (GPC), a glass transition temperature determined by differential scanning calorimetry (DSC) according to ASTM D3418-82, from 30 to 80° C. and a viscosity in the molten state measured at 200° C. with a cone/plate viscosimeter according to ASTM D4287-88 from 1 to 25,000 mPa.s.

Radiation curable powder composition according to any of the preceding claims, wherein the ethylenically unsaturated oligomer is an epoxy(meth)acrylate, an urethane(meth)acrylate, an acrylic(meth)acrylate or tri(meth)acrylate of tris(2-hydroxyethyl)isocyanurate.

Radiation curable powder composition according to any of the preceding claims which comprises from 0 to 20 weight percentage of an ethylenically unsaturated oligomer based on the total weight of the components a), b) and c).

Radiation curable powder composition according to any of the preceding claims, wherein the (meth)acryloyl group containing semi-crystalline polyester has a degree of unsaturation of 0.18 to 1.80, preferably of 0.35 to 1.25 milliequivalents of double bounds per gram of polyester, a number average molecular weight between 1,000 and 21,000, preferably between 1,300 and 9,000, measured by gel permeation chromatography (GPC), a well-defined melting point of between 60 and 150° C., determined by differential scanning calorimetry (DSC) according to ASTM D3418-82 and a viscosity in the molten state of less then 10,000 mPa.s measured at 175° C. with a cone/plate viscosimeter according to ASTM D4287-88.

Radiation curable powder composition according to any of the preceding claims, which comprises from 0 to 30 weight percentage of the (meth)acryloyl group containing semi-crystalline polyester based on the total weight of the components a), b) and c).

Radiation curable powder composition according to any of the preceding claims, which additionally comprises up to 15, preferably 0.5 to 8 parts by weight of a photo-initiator for 100 parts by weight of the total of the amorphous polyester a), the polyphenoxy resin b) and the ethylenically unsaturated oligomer and/or semi-crystalline polyester c) and optionally a photo-activator.

Radiation curable powder composition according to any of the preceding claims, which additionally comprises from 0 to 10 parts by weight of at least one coating properties modifying substance for 100 parts by weight of the total of the amorphous polyester a), the polyphenoxy resin b) and the ethylenically unsaturated oligomer and/or semi-crystalline polyester c).

(meth)acryloyl group containing amorphous polyester obtainable from the reaction of a di-isocyanate with a hydroxyalkyl(meth)acrylate and a hydroxyl group containing polyester or the reaction of glycidyl(meth)acrylate with a polyester containing carboxyle groups obtainable by the reaction of a hydroxyl group containing polyester with a polyacid, characterised in that the hydroxyl group containing polyester is the reaction product of a) an acid constituent which contains from 50 to 100 mole percentage of terephthalic acid or isophtalic acid, alone or in admixture, and from 0 to 50 mole percentage of at least one other saturated aliphatic, cycloaliphatic or aromatic di- or polycarboxylic acid and b) a stoichiometric excess, on the acid constituents, of an alcohol constituent which contains from 20 to 100 mole percentage of neopentyl glycol and from 0 to 80 mole percentage of at least one other aliphatic or cycloaliphatic di- or polyol.