Branched olefinic macromonomer, olefin graft copolymer, and olefin resin composition

An olefin graft copolymer obtained by copolymerizing an atactic branched macromonomer, wherein the macromonomer is derived from monomers selected from the group consisting of (1) propylene and (2) the combination of propylene and at least one selected from ethylene, α-olefins having from 4 to 20 carbon atoms, cyclic olefins and styrenes, and of which the propylene content falls between 0.1 and 100 mol %, and which macromonomer satisfies the following (a) and (b):

• (a) its weight-average molecular weight (Mw) measured through gel permeation chromatography (GPC) falls between 400 and 200000;
• (b) its vinyl content is at least 70 mol % of all the unsaturated groups in the macromonomer, wherein the macromonomer satisfies each of the following (i), (ii) and (iii):
• (i) the ratio of the temperature dependency (E2) of the macromonomer solution viscosity to the temperature dependency (E1) of the solution viscosity of the linear polymer which has the same type of monomer, the same chemical composition and the same intrinsic viscosity as those of the macromonomer, E2/E1, satisfies the following relationship:
• 1.01<E2/E1<2.5;
• (ii) the ratio of the number-average molecular weight measured through GPC (GPC-Mn) to the number-average molecular weight measured through 13C-NMR (NMR-Mn) of the macromonomer satisfies the following relationship:
• (GPC-Mn)/(NMR-Mn)>1;
• (iii) the macromonomer has branches existing not at the α- and/or β-substituents of the monomer that constitutes the macromonomer, and the number of the branches falls between 0.01 and 40 in one molecule of the macromonomer,
• with at least one comonomer selected from ethylene, propylene, α-olefins having from 4 to 20 carbon atoms, cyclic olefins and styrenes, in the presence of a metallocene catalyst.