Method for producing graft-modified copolymers

A method for producing a graft-modified copolymer comprising subjecting:

• 100 parts by weight of an unsaturated copolymer which has a number average molecular weight of 3,000-1,000,000;
• and
• from 0.1 to 300 parts by weight of a radically polymerizable monomer selected from the group consisting of vinyl monomers, vinylidene monomers, alpha, beta-unsaturated carboxylic acids and derivatives thereof to radical polymerization conditions thereby to introduce a polymer chain formed from said radically polymerizable monomer;
• wherein said unsaturated copolymer is obtained by copolymerizing propylene and a cyclic olefin selected from the group consisting of 5-vinylbicyclo[2,2,2]hept-2-ene and 8-ethylidenetetra-cyclo[4,4,0,1.sup.2,5,1.sup.7,10 ]-3-dodecene, the concentration of a repeating unit originating from said cyclic olefin in said unsaturated copolymer being from 0.05 to 50 mol %.