Epoxy resin powder including ethylene vinyl acetate

DETAILED DESCRIPTION I claim: 1.
A homogeneous free-flowing powder which is shelf-stable and when heated to 185.
degree.
-250.
degree.
C in contact with a metal article fuses and then gels to provide a tough protective coating, said powder comprising a polyglycidyl ether of a polyhydric phenol having a softening point of 70.
degree.
-150.
degree.
C, a normally solid latent hardening agent for epoxy resin, a latent catalyst for accelerating reaction between the polyglycidyl ether and the hardening agent when melted together, which powder is characterized by the feature that it incorporates per 100 parts of the polyglycidyl ether 3-30 parts by weight of one or more copolymers of monomers comprising by weight 2-50% vinyl acetate and 5-75% ethylene, which copolymer or copolymers have a melt index or combined melt index of 5-400 and impart extraordinarily good flexibility to cured coatings of the powder without undue effect upon other properties of the coatings.
2.
A powder as defined in claim 1 wherein a said copolymer is a copolymer of 25-50 weight percent of vinyl acetate and 50-75 weight percent of ethylene.
3.
A powder as defined in claim 1 wherein a said copolymer is also based on about 1 weight percent of acrylic acid or maleic acid.
4.
A powder as defined in claim 1 wherein the composition includes 3-10 parts by weight of said copolymer or copolymers per 100 parts of the polyglycidyl ether.
5.
A powder as defined in claim 1 wherein said one or more copolymers have a melt index or combined melt index of 20-200.
6.
A dry shelf-stable powder as defined in claim 1, most of which will pass a screen having 180-micrometer openings.




Description:
FIELD OF THE INVENTION This invention concerns epoxy resin powder used to provide protective coatings, especially for petroleum pipelines.
BACKGROUND OF THE INVENTION Thermosetting epoxy resin powders are widely used to provide protective coatings, especially for steel pipe.
The coatings may be applied by blowing the powder onto pipe which has been preheated to a temperature above the softening point of the powder so that the powder fuses and adheres to the pipe