Copolymers of ethylene and unsaturated ester.

摘要

A random copolymer comprises ethylene units which preferably forms a polyethylene chain and 0.001 to 10 mol% of ester units which are ethylenically alpha , beta -unsaturated acid esters represented by the formula (I) or (II):
<CHEM>
wherein R<1> is H or -CH3 and R<2> is a halogenated, preferably fluorinated C1 - 15 alkyi group;
<CHEM>
wherein R<3> is H or -CH3 and n = 0 or 1; optionally up to 10 mol% of a modifying comonomer may be present.
<??>Production is by catalytic radical polymerisation of the monomers or by grafting the ester unit onto a polymer or copolymer of ethylene.
<??>The copolymer may be blended with other polymers, may be crosslinked, and is extruded into wire or cable coatings or molded into sheets, films, or laminates.
<??>The copolymer has excellent dielectric breakdown characteristics, such as electricity treeing or water treeing property, and is useful as insulation for high-voltage cables.