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Abstract

Powder coating compositions suitable for use in the manufacture of laser-engraved printing rollers, comprise (a) a difunctional epoxy resin prepared from a bisphenol, (b) an epoxy resin having an epoxide functionality greater than 2, (c) a diaminodiphenylsulphone as hardener for the mixture of resins (a) and (b), and (d) an imidazole as curing accelerator. These compositions, when applied to a metal base member, fused, and cured, provide a surface that is easily engravable yet has excellent resistance to chemical attack and physical wear. Typical difunctional epoxy resins (a) are 2,2-bis(4-glycidyloxyphenyl)propane advanced with bisphenol A, while typical epoxy resins that may be used as (b) include polyglycidyl ethers of phenol-formaldehyde novolaks. The hardener (c) my be, for example, 3,3'- and 4,4'-diaminodiphenylsulphones and the imidazole accelerator (d) may be 2-methylimidazole or benzimidazole.

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