To obtain a comb copolymer having a high molecular weight and a polymer chain having a uniform comonomer distribution by polymerizing at least one monomer being either an olefinically unsaturated 2-18 C hydrocarbon or a vinyl aromatic compound with at least either a long-chain 1-(20-40 C) alkene or a macromonomer in the presence of a metallocene catalyst.

The olefinically unsaturated hydrocarbon monomer is ethylene, propylene, 1-butene, 1-hexene or norbornene among which propylene is particularly desirable. The vinyl aromatic compound monomer is desirably styrene, α-styrene, divinylbenzene or 2vinylnaphthalene. The long-chain 1-alkene is exemplified by 1eicosene. The macromonomer is desirably a vinyl- or vinylideneterminated oligomer. The monomer is suitably styrene, αmethylstyrene, 2-vinylnaphthalene, 1,3-butadiene, isoprene or isobutylene. A compatibilizer for a polyblend can thus be obtained.