High-density polyethylene mixed resin particles, composite resin particles, foamed particles and foamed molded body
High-density polyethylene mixed resin particles used as seed particles during seed polymerization, wherein said seed particles contain a mixed resin of 100 parts by weight of high-density polyethylene and 20 to 100 parts by weight of an ethylene copolymer; said high-density polyethylene has a density of 935 to 960 kg/m 3 and a softening temperature of 115 to 130° C.; said ethylene copolymer is a copolymer of an ester-based monomer selected from an acrylic acid alkyl ester and an aliphatic saturated monocarboxylic acid vinyl, and etylene, contains 1 to 20% by weight of an ester-based monomer-derived component, and has a softening temperature of 75 to 110° C.; said acrylic acid alkyl ester is selected from methyl acrylate and ethyl acrylate; and said aliphatic saturated monocarboxylic acid vinyl is selected from vinyl acetate and vinyl propionate.
1. High-density polyethylene mixed resin particles used as seed particles during seed polymerization, wherein:
said seed particles contain a mixed resin of 100 parts by weight of high-density polyethylene and 20 to 100 parts by weight of an ethylene copolymer;
said high-density polyethylene has a density of 935 to 960 kg/m 3 and a softening temperature of 115 to 130° C.;
said ethylene copolymer is a copolymer of an ester-based monomer selected from an acrylic acid alkyl ester and an aliphatic saturated vinyl monocarboxylic acid, and ethylene, contains 1 to 20% by weight of an ester-based monomer-derived component, and has a softening temperature of 75 to 110° C.;
said acrylic acid alkyl ester is selected from methyl acrylate and ethyl acrylate; and
said aliphatic saturated monocarboxylic acid vinyl is selected from vinyl acetate and vinyl propionate.
2. The high-density polyethylene mixed resin particles according to claim 1 , wherein said ethylene copolymer has a MFR of 0.2 to 1.0 g/10 minutes and contains 3 to 15% by weight of said ester-based monomer-derived component.
3. Composite resin particles comprising a resin content containing 100 parts by weight of a high-density polyethylene mixed resin derived from said high-density polyethylene mixed resin particles according to claims 1 ; and 100 to 500 parts by weight of a styrene-based polymer obtained by impregnating and polymerizing a styrene-based monomer in said seed particles.
4. The composite resin particles according to claim 3 , wherein said composite resin particles contain 1.5 to 6.0 parts by weight of a flame retardant with respect to 100 parts by weight of said resin content.
5. The composite resin particles according to claim 4 , wherein said flame retardant is a halogen-based flame retardant.
6. The composite resin particles according to claim 4 , further comprising a flame retardant auxiliary agent, wherein said flame retardant auxiliary agent is selected from dicumyl peroxide, 2,3-dimethyl-2,3-diphenyl butane, 3,4-dimethyl-3,4-diphenyl hexane, and cumene hydroperoxide.
7. Expanded particles obtained by impregnating a blowing agent into the composite resin particles according to claim 3 , followed by expanding, the expanded particles having a bulk density of 50 to 15 kg/m 3 .
8. An expanded molded article obtained by expansion molding the expanded particles according to claim 7 .