| abstract |
A tackifier (B) according to the present invention comprises a structural unit derived from α-methylstyrene or isopropenyltoluene and a structural unit derived from styrene, and comprises a copolymer (C) that satisfies the following (i) to (iii): (i) a content of the structural unit derived from α-methylstyrene or isopropenyltoluene is in the range of 30 to 70 mol%, (ii) a softening temperature (Tm) measured by the ring-and-ball method according to JIS K 2207 is in the range of 110°C to 170°C, and (iii) a content of a fraction having molecular weight of not more than 350, as determine by gel permeation chromatography (GPC) and calculated from polystyrene standard, is less than 1.5 mass%. |