Method for producing skin-covered foamed molded article and resulting product

摘要

A method for producing a skin-covered foamed molded article includes blow molding a parison into a skin and heating expanded polystyrene beads filled in a hollow space of the skin to form a foam layer fuse-bonded to the skin, polystyrene resin composition having specific Charpy impact strength, MFR and branching degree. The skin of the skin-covered foamed molded article is formed of the specific polystyrene resin composition.

主权项

1. A method for producing a skin-covered foamed molded article, the method comprising the steps of:
(a) providing a parison that is in a molten or softened state, the parison being formed of a polystyrene resin composition; (b) blow molding the parison into a skin defining a hollow interior space; (c) filling expanded polystyrene beads in the hollow interior space; and (d) heating the expanded polystyrene beads filled in the hollow interior space to fuse-bond the expanded polystyrene beads to each other and to form a foam layer fuse-bonded to the skin, wherein step (a) comprises:
melting and kneading a mixture of 30 to 70 parts by weight of a polystyrene resin (A) having a branching degree defined as MwA(abs)/MwA(r) of at least 1.4, where MwA(abs) and MwA(r) represent a weight average absolute molecular weight and a linear polystyrene equivalent weight average molecular weight, respectively, of the polystyrene resin (A), and 30 to 70 parts by weight of an impact resistant polystyrene resin (B) containing a rubber component to obtain the polystyrene resin composition, and extruding the polystyrene resin composition into the parison, wherein the total of the polystyrene resin (A) and impact resistant polystyrene resin (B) is 100 parts by weight, wherein the polystyrene resin composition meets the following requirements (1) to (3): (1) the polystyrene resin composition has a Charpy impact strength at 23° C. according to ISO179/1eA of at least 5 kJ/m2; (2) the polystyrene resin composition has a melt mass flow rate at a temperature of 200° C. and a load of 5 kg of 1.5 to 3.0 g/10 min; (3) the polystyrene resin composition has a branching degree defined as MwS(abs)/MwS(r) of at least 1.4 where MwS(abs) and MwS(r) represent a weight average absolute molecular weight and a linear polystyrene equivalent weight average molecular weight, respectively, of the polystyrene resin composition, and wherein the polystyrene resin (A) comprises a copolymer of a styrenic monomer with a multibranched macromonomer having a plurality of polymerizable double bonds.