Mitsubishi Chemical Basf Company Limited

Masayuki Tanaka

Hiroki Shinozaki

Yonezo Ueda

Takanori Suzuki

Kenji Haraguchi

Hiromi Yamanaka

Mitsuo Furuichi

Expandable styrene resin beads are described, which, when expanded to a bulk density of 20 g/l, give pre-expanded beads in which the number of cells present along those surface parts of radii which range from the bead surface to a depth of 0.2 mm from the surface is from 3 to 20 per mm and to the bead center is 10 or larger per mm, the number of the number of cells present along those inner parts of the radii which range from a depth of 1 mm from the bead surface to the bead center is 10 or larger per mm, the number of cells present along said surface parts being smaller than the number of cells present along said inner parts.

Suspension-polymerization process for producing expandable styrene resin

An expandable styrene resin bead containing voids therein, wherein the number of the voids present in the area from the surface of the bead to a depth of 0.1 mm along the radial direction is not more than 100 per mm.sup.2 as counted on a cross section passing through approximately the center of the bead. A process for producing expandable styrene resin beads by suspension polymerization is also disclosed in which a styrene monomer is suspended in an aqueous medium in the presence of an initiator and a suspending agent, and a blowing agent is incorporated into polymer beads produced, wherein an alkali metal salt or ammonium salt of persulfuric acid is added to the reaction system in an amount of 0.5 to 30 ppm based on the aqueous medium while the degree of conversion of said monomer is in the range of from 0 to 30%, and an electrolyte is added to the reaction system in a concentration of 0.02 to 5.0 mol/l based on the aqueous medium when the degree of conversion is 30% or higher. The expandable styrene resin bead does not require aging and, when pre-expanded, show little variation in the state of the cells, i.e., expandable styrene resin beads which hardly undergo influences of storage conditions.

Expandable styrene resin beads and process for producing the same

Expandable rubber-modified styrene resin beads, expanded rubber-modified styrene resin beads, and expanded molded rubber-modified styrene resin articles are described. The expandable beads comprise a rubber-modified styrene resin comprising a styrene resin having dispersed therein 8 to 15% by weight of conjugated diene rubber particles having a 1,4-cis structure in a proportion of not less than 70% and an average particle size of 1.5 to 3.0 .mu.m, the rubber-modified styrene resin having a mineral oil content of not more than 3.0% by weight, and the expandable rubber-modified styrene resin beads containing 1 to 15% by weight of a volatile blowing agent. The expanded molded article has excellent appearance, impact resistance and softness.

Expandable rubber-modified styrene resin beads, expanded beads thereof,

Expandable styrene resin beads are described, which, when expanded to a bulk density of 20 g/l, give pre-expanded beads in which the number of cells present along those surface parts of radii which range from the bead surface to a depth of 0.2 mm from the surface is from 3 to 20 per mm and the number of cells present along those inner parts of the radii which range from a depth of 1 mm from the bead surface to the bead center is 10 or larger per mm, the number of cells present along said surface parts being smaller than the number of cells present along said inner parts.

Growing community of inventors

Mie, Japan

Masayuki Tanaka