Resin modifier, resin composition, molding, and molded article

A resin modifier (Y) comprising:

• a block polymer (X) that has a block of a hydrophobic polymer (a) and a block of a hydrophilic polymer (b) as constitutional units,
• the block polymer (X) having an orientation index (ω) obtained by the following formula of 1.5 to 15:
• orientation index (ω)=(β)/(α),
• wherein (α) represents a weight ratio [(αb)/(αa)] between the hydrophilic polymer (b) and the hydrophobic polymer (a) in the block polymer (X), and
• (β) represents a weight ratio [(βb)/(βa)] between the hydrophilic polymer (b) and the hydrophobic polymer (a) determined by reflective infrared spectroscopy of the block polymer (X) heat-melted and pressed to a thickness of 500 μm, and
• wherein the hydrophobic polymer (a) is a polyolefin (a2),
• the polyolefin (a2) is an ethylene-propylene copolymer having a reactive group at one end and having 30 mol % or more and 96 mol % or less of a propylene-derived constitutional unit,
• the hydrophilic polymer (b) is a polyether (b1), and
• the polyether (b1) is at least one selected from the group consisting of a polyether monool (b1-1), a polyether monoamine (b1-2) and a modified product of either one of these (b1-3),
• the polyether monool (b1-1) is a polyether monool represented by the formula (1):
• wherein R1 and R2 are each independently a C1-C12 hydrocarbon group;
• Q1 is an oxygen atom or a nitrogen atom;
• h is 0 when Q1 is an oxygen atom and h is 1 when Q1 is a nitrogen atom;
• R3 and R4 are each independently a C1-C4 alkylene group;
• (R30)s may be the same as or different from each other and the bonding form thereof may be a block form or a random form;
• and i is an integer of 10 to 250, and
• the polyether monoamine (b1-2) is a polyether monoamine represented by the formula (2):
• wherein R5 and R6 are each independently a C1-C12 hydrocarbon group;
• Q2 is an oxygen atom or a nitrogen atom;
• j is 0 when Q2 is an oxygen atom and j is 1 when Q2 is a nitrogen atom;
• R7 is a C1-C4 alkylene group;
• R8 is a C2-C4 alkylene group;
• (R7O)s may be the same as or different from each other and the bonding form thereof may be a block form or a random form;
• and k is an integer of 10 to 250.