Block polymer, thermoplastic resin composition and molded article

A block polymer (X) comprising, as structural units, a polyolefin structure derived from a polyolefin (A) below and a polyolefin structure derived from a polyolefin (B) below,

• wherein the polyolefin (A) contains a C3-C8 α-olefin as a structural monomer with α-olefin portions having an isotacticity of 70 to 100%, has a number average molecular weight of 1000 to 200000, and has a carbon-carbon double bond number of 0.01 to 8.0 per 1000 carbon atoms,
• wherein the polyolefin (B) contains a C3-C8 α-olefin as a structural monomer with α-olefin portions having an isotacticity of 1 to 65%, and has a number average molecular weight of 1000 to 200000,
• wherein the block polymer (X) has a structure in which the polyolefin structure derived from the polyolefin (A) and the polyolefin structure derived from the polyolefin (B) are bonded via a binder (γ) below,
• wherein the binder (γ) comprises at least one selected from the group consisting of an unsaturated (poly)carboxylic acid (anhydride) (C), a hydroxy group-containing compound (F), an epoxy group-containing compound (P), an isocyanate group-containing compound (L), a carboxyl group-containing compound (K), and an aminocarboxylic acid (H), and
• wherein the block polymer (X) has any one of the structures
• (1):
• [(A)-(B)]n block polymer, wherein n=1 to 5,
• (2):
• (A)-(B)-(A) block polymer, or
• (3):
• (B)-(A)-(B) block polymer.