To obtain a styrene-based resin having excellent impact resistance and moldability.
This styrene-based resin satisfies relations of equation I: Δlnλn/Δ=(lnλn2-lnλn1)/(2-1)≥0.15, equation II: λn=λ/λ1 and equation III: =ln(l/l0) (λn is a nonlinear parameter; λ is an elongation viscosity in a nonlinear region; λ1 is an elongation viscosity in a linear region; is a Hencky elongation strain amount; l0 and l are each length of a sample at an elongation time 0 and t, respectively) in an elongation viscosity measurement at 130°C in a range of 0.0025-0.0035 sec-1 elongation rate. The weight-average molecular weight Mw of the styrene-based resin is about 1.5×105 to 7×105. The branch parameter g (=[μ]branch/[μ]linear) ([μ]branch is an intrinsic viscosity of a branch-chain polymer and [μ]linear is an intrinsic viscosity of a straight-chain polymer having the same weight-average molecular weight as that of the branch-chain polymer) is about 0.5-0.99.
NISHIMURA KENJI
KAKUMOTO SATOSHI
