Pre-expanded particle of olefin-modified polystyrene resin, process for producing the same, and molded foam
AssigneeSekisui Plastics Co., Ltd.
InventorsNaokuni Inada, Hideyasu Matsumura, Yasutaka Tsutsui, Ikuo Morioka
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Abstract
A pre-expanded beads of olefin-modified polystyrene-based resin comprising a pie-expanded beads of a polystyrene-based resin modified with a polyolefin-based resin, wherein a styrene-based monomer forming a polystyrene-based resin in the beads is used in the range of 100 to 1,000 parts by weight relative to 100 parts by weight of a polyolefin-based resin, a bulk density of each bead is 0.012 to 0.20 g/cm3, and an absorbance ratio at 698 cm−1 and 2850 cm−1 (D698/D2850) obtained from an infrared absorption spectrum of each bead surface measured by ATR method infrared spectroscopy is in the range of 0.1 to 2.5.
Claims18
Pre-expanded beads of styrene-modified polyolefin-based resin comprising pre-expanded beads of a polyolefin-based resin modified with a polystyrene-based resin, wherein a styrene-based monomer forming a polystyrene-based resin in the beads is used in the range of 120 to 1,000 parts by weight relative to 100 parts by weight of a polyolefin-based resin, a bulk density of each bead is 0.012 to 0.20 g/cm3, and an absorbance ratio at 698 cm−1 and 2850 cm−1 (D698/D2850) obtained from an infrared absorption spectrum of each bead surface measured by ATR method infrared spectroscopy is in the range of 0.1 to 2.5.
A method for producing pre-expanded beads of styrene-modified polyolefin-based resin comprising the steps of:
- (a) polymerizing a styrene-based monomer (120 to 1,000 parts by weight relative to 100 parts by weight of polyolefin-based resin beads to be used) while impregnating polyolefin-based resin beads with the styrene-based monomer, in the presence of a polymerization initiator in an aqueous medium in which the polyolefin-based resin beads are dispersed, to obtain the styrene-modified polyolefin-based resin beads,
- (b) impregnating the resin beads with a blowing agent, and
- (c) pre-expanding the resin beads impregnated the blowing agent to obtain the pre-expanded beads of olefin-modified polystyrene-based resin,
- wherein in the step (a), the aqueous medium is stirred at a power required for stirring of 0.06 to 0.8 kw/m3, and impregnation and polymerization of the styrene-based monomer are performed under a condition where a styrene-based monomer content in the polyolefin-based resin beads is 35% by weight or less;
- and wherein in the step (a), the polymerization initiator is added at 0.02 to 2.0% by weight of a total amount of the polyolefin-based resin beads to be used and the styrene-based monomer until an amount of the styrene-based monomer to be used reaches 40 to 90% by weight of the total amount of the styrene-based monomer to be used, and then a styrene-based monomer containing no polymerization initiator is added.
Dependencies are inferred from the claim text.