JP2020050784A - Composite resin particle, expandable particle, expanded particle, and expanded molded body - Google Patents

Composite resin particle, expandable particle, expanded particle, and expanded molded body Download PDF

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JP2020050784A
JP2020050784A JP2018182395A JP2018182395A JP2020050784A JP 2020050784 A JP2020050784 A JP 2020050784A JP 2018182395 A JP2018182395 A JP 2018182395A JP 2018182395 A JP2018182395 A JP 2018182395A JP 2020050784 A JP2020050784 A JP 2020050784A
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particles
composite resin
resin
density polyethylene
ethylene
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JP6944914B2 (en
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皓樹 大脇
Koki Owaki
皓樹 大脇
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Sekisui Kasei Co Ltd
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Sekisui Plastics Co Ltd
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Abstract

To provide a composite resin particle capable of manufacturing an expanded molded body of which mechanical strength and heat resistance are improved, at good molding processability.SOLUTION: There is provided a composite resin particle for expansion, containing a high density polyethylene resin, an ethylenic copolymer having a carbonyl group, and a polystyrene resin, in which the high density polyethylene resin, the ethylenic copolymer having the carbonyl group, and the polystyrene resin are contained at following mass ratios: (i) total amount of the high density polyethylene resin and an ethylenic copolymer having the carbonyl group/the polystyrene resin=5/95 to 40/60, (ii) the high density polyethylene resin/the ethylenic copolymer having the carbonyl group=5/95 to 50/50, the composite resin particle has a structure in which a surface absorbance ratio D1 (D698/D2850), which is a ratio of absorbance at 2850 cm(D2850) and absorbance at 698 cm(D698) calculated from an infrared absorption spectrum obtained by infrared spectroscopic analysis by an ATR method on a surface thereof, and a surface absorbance ratio D2 (D698/D2850), which is a ratio of absorbance at 2850 cm(D2850) and absorbance at 698 cm(D698) calculated from the infrared absorption spectrum obtained by infrared spectroscopic analysis by an ATR method on a surface of an expanded molded body constituted by a fusion body of an expanded particle derived from the composite resin particle, exhibit D1=0.5 to 2.5 and D2/D1=0.1 to 0.95, and the high density polyethylene resin has density of 935 to 960 kg/m.SELECTED DRAWING: None

Description

本発明は、複合樹脂粒子、発泡性粒子、発泡粒子及び発泡成形体に関する。具体的には、本発明は、機械強度及び耐熱性が改善された発泡成形体を成形加工性よく製造可能な複合樹脂粒子、その複合樹脂粒子に由来する発泡性粒子、発泡粒子及び発泡成形体に関する。   The present invention relates to composite resin particles, expandable particles, expanded particles, and expanded molded articles. Specifically, the present invention relates to a composite resin particle capable of producing a foamed molded article having improved mechanical strength and heat resistance with good moldability, an expandable particle derived from the composite resin particle, a foamed particle, and a foamed molded article. About.

従来、樹脂成分としてポリスチレン系樹脂を含む発泡成形体が、成形加工性、断熱性、耐衝撃性、緩衝性等の優れた物性を有するため、包装用緩衝材、自動車用構造部材、建築用部材等として幅広く使用されている。
緩衝材の用途では、発泡成形体にはより高い耐衝撃性が特に求められるようになっている。そのため、このような特性を満たすものとして、樹脂成分としてポリスチレン系樹脂及びポリエチレン系樹脂を含む発泡成形体が提案されている（特許第６１８５８７２号公報：特許文献１）。
特許文献１には、種粒子１００質量部と、種粒子にスチレン系モノマーを含浸重合させて得られたスチレン系重合体１００〜５００質量部とからなる樹脂分を含む複合樹脂粒子に由来する発泡成形体が記載されている。また、種粒子は、高密度ポリエチレン１００質量部とエチレン共重合体２０〜１００質量部との混合樹脂を含み、
高密度ポリエチレンが、９３５〜９６０ｋｇ／ｍ３の密度と１１５〜１３０℃の軟化温度を有し、
エチレン共重合体が、アクリル酸アルキルエステル及び脂肪族飽和モノカルボン酸ビニルから選択されるエステル系モノマーとエチレンとの共重合体であり、エステル系モノマー由来成分を１〜２０質量％含み、７５〜１１０℃の軟化温度を有し、
アクリル酸アルキルエステルが、アクリル酸メチル及びアクリル酸エチルから選択され、
脂肪族飽和モノカルボン酸ビニルが、酢酸ビニル及びプロピオン酸ビニルから選択される、と記載されている。 Conventionally, foamed molded articles containing a polystyrene-based resin as a resin component have excellent physical properties such as moldability, heat insulation properties, impact resistance, and cushioning properties. Widely used as such.
In applications of cushioning materials, foamed molded articles are particularly required to have higher impact resistance. Therefore, a foamed molded article containing a polystyrene-based resin and a polyethylene-based resin as a resin component has been proposed to satisfy such characteristics (Japanese Patent No. 6185873: Patent Document 1).
Patent Literature 1 discloses foaming derived from a composite resin particle containing a resin component consisting of 100 parts by mass of seed particles and 100 to 500 parts by mass of a styrene-based polymer obtained by impregnating and polymerizing a styrene-based monomer in the seed particles. Moldings are described. The seed particles include a mixed resin of 100 parts by mass of high-density polyethylene and 20 to 100 parts by mass of an ethylene copolymer,
The high density polyethylene has a density of 935 to 960 kg / m 3 and a softening temperature of 115 to 130 ° C.,
The ethylene copolymer is a copolymer of ethylene and an ester monomer selected from an alkyl acrylate and an aliphatic saturated vinyl monocarboxylate, and contains 1 to 20% by mass of a component derived from the ester monomer; Has a softening temperature of 110 ° C.,
The alkyl acrylate is selected from methyl acrylate and ethyl acrylate;
It is stated that the aliphatic saturated vinyl monocarboxylate is selected from vinyl acetate and vinyl propionate.

特許第６１８５８７２号公報Japanese Patent No. 6185873

特許文献１の実施例ではエチレン酢酸ビニル共重合体がエチレン共重合体として使用されている。しかし、特許文献１は、高密度ポリエチレン系樹脂量に対するエチレン共重合体量が少ないため、複合樹脂粒子に由来する発泡成形体の機械強度及び耐熱性、発泡成形体を製造する際の成形加工性に改善の余地があった。   In the example of Patent Document 1, an ethylene vinyl acetate copolymer is used as an ethylene copolymer. However, in Patent Document 1, since the amount of the ethylene copolymer is small relative to the amount of the high-density polyethylene resin, the mechanical strength and heat resistance of the foamed molded article derived from the composite resin particles, and the moldability in producing the foamed molded article. Had room for improvement.

本発明者は、鋭意検討の結果、エチレン共重合体の存在位置を特定の範囲内とすることで、エチレン酢酸ビニル共重合体のようなカルボニル基を有するエチレン共重合体を多く使用しても、発泡成形体の機械強度及び耐熱性、発泡成形体を製造する際の成形加工性を改善できることを見出し、本発明に至った。   The present inventor has conducted extensive studies and found that by setting the position of the ethylene copolymer within a specific range, even when using a large amount of an ethylene copolymer having a carbonyl group such as an ethylene vinyl acetate copolymer, The present inventors have found that the mechanical strength and heat resistance of the foamed molded article and the moldability at the time of producing the foamed molded article can be improved, and the present invention has been accomplished.

かくして本発明によれば、高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂とを含む発泡用の複合樹脂粒子であって、
高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂とが、以下の質量比：
（ｉ）前記高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体の合計量／ポリスチレン系樹脂＝５／９５〜４０／６０、
（ｉｉ）前記高密度ポリエチレン系樹脂／カルボニル基を有するエチレン系共重合体＝５／９５〜５０／５０
で含まれ、
前記複合樹脂粒子は、
・その表面をＡＴＲ法により赤外分光分析することで得られる赤外線吸収スペクトルから算出された２８５０ｃｍ−１の吸光度（Ｄ２８５０）と６９８ｃｍ−１の吸光度（Ｄ６９８）との比である表面吸光度比Ｄ１（Ｄ６９８／Ｄ２８５０）と、
・前記複合樹脂粒子に由来する発泡粒子の融着体から構成される発泡成形体の表面をＡＴＲ法により赤外分光分析することで得られる赤外線吸収スペクトルから算出された２８５０ｃｍ−１の吸光度（Ｄ２８５０）及び６９８ｃｍ−１の吸光度（Ｄ６９８）との比である表面吸光度比Ｄ２（Ｄ６９８／Ｄ２８５０）とが、下記値：
Ｄ１＝０．５〜２．５、
Ｄ２／Ｄ１＝０．１〜０．９５
を示す構造を有し、
前記高密度ポリエチレン系樹脂が、９３５〜９６０ｋｇ／ｍ３の密度を有することを特徴とする複合樹脂粒子が提供される。 Thus, according to the present invention, foamed composite resin particles comprising a high-density polyethylene resin and an ethylene copolymer having a carbonyl group and a polystyrene resin,
The mass ratio of the high-density polyethylene resin, the ethylene copolymer having a carbonyl group, and the polystyrene resin is as follows:
(I) the total amount of the high-density polyethylene-based resin and the ethylene-based copolymer having a carbonyl group / polystyrene-based resin = 5/95 to 40/60;
(Ii) The high-density polyethylene-based resin / ethylene-based copolymer having a carbonyl group = 5/95 to 50/50
Included in
The composite resin particles,
Part surface ATR method by infrared spectroscopy absorbance of 2850 cm -1, which is calculated from the infrared absorption spectrum obtained by (D2850) to the absorbance of 698cm -1 (D698) and the surface absorbance ratio is the ratio of D1 ( D698 / D2850),
An absorbance of 2850 cm −1 (D2850) calculated from an infrared absorption spectrum obtained by performing infrared spectroscopy analysis on the surface of a foamed molded product composed of a fusion body of foamed particles derived from the composite resin particles by the ATR method; ) And the absorbance at 698 cm -1 (D698), the surface absorbance ratio D2 (D698 / D2850), are the following values:
D1 = 0.5-2.5,
D2 / D1 = 0.1 to 0.95
Having a structure showing
Composite resin particles are provided, wherein the high-density polyethylene resin has a density of 935 to 960 kg / m 3 .

また、本発明によれば、上記複合樹脂粒子と、発泡剤とを含む発泡性粒子が提供される。
更に、本発明によれば、上記発泡性粒子を発泡させて得られた発泡粒子が提供される。
また、本発明によれば、上記発泡粒子を発泡成形させて得られた発泡成形体が提供される。 Further, according to the present invention, there is provided an expandable particle containing the composite resin particle and a blowing agent.
Further, according to the present invention, there is provided expanded particles obtained by expanding the expandable particles.
Further, according to the present invention, there is provided a foam molded article obtained by subjecting the above-mentioned foam particles to foam molding.

本発明によれば、機械強度及び耐熱性が改善された発泡成形体を成形加工性よく製造可能な複合樹脂粒子を提供できる。
以下のいずれかの場合、より機械強度及び耐熱性が改善された発泡成形体を成形加工性よく製造可能な複合樹脂粒子を提供できる。
（１）カルボニル基を有するエチレン系共重合体がエチレン酢酸ビニル共重合体であり、エチレン酢酸ビニル共重合体が酢酸ビニル由来成分を１〜２０質量％含む。
（２）高密度ポリエチレンが、４０ｍＮ以上の１６０℃における溶融張力を有する。
（３）複合樹脂粒子が、高密度ポリエチレンとエチレン酢酸ビニル共重合体とを含む種粒子と、種粒子に含浸重合したスチレン系モノマー由来のポリスチレン系樹脂とを含む。
（４）高密度ポリエチレンの融点（Ｔ１）とエチレン酢酸ビニル共重合体の融点（Ｔ２）の差が１０〜４０℃であり、かつ種粒子の軟化温度（Ｔ３）が１１０〜１２５℃である。 ADVANTAGE OF THE INVENTION According to this invention, the composite resin particle which can manufacture a foaming molded object with improved mechanical strength and heat resistance with good moldability can be provided.
In any of the following cases, it is possible to provide a composite resin particle capable of producing a foamed molded article having improved mechanical strength and heat resistance with good moldability.
(1) The ethylene-based copolymer having a carbonyl group is an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer contains 1 to 20% by mass of a component derived from vinyl acetate.
(2) The high-density polyethylene has a melt tension at 160 ° C. of 40 mN or more.
(3) The composite resin particles include seed particles containing high-density polyethylene and an ethylene-vinyl acetate copolymer, and a polystyrene resin derived from a styrene-based monomer impregnated and polymerized in the seed particles.
(4) The difference between the melting point (T1) of the high-density polyethylene and the melting point (T2) of the ethylene-vinyl acetate copolymer is 10 to 40C, and the softening temperature (T3) of the seed particles is 110 to 125C.

（複合樹脂粒子）
複合樹脂粒子は、高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂とを含む。なお、「複合」とは、粒子中に高密度ポリエチレン系樹脂とポリスチレン系樹脂とが存在することを意味する。 (Composite resin particles)
The composite resin particles include a high-density polyethylene resin, an ethylene copolymer having a carbonyl group, and a polystyrene resin. Note that “composite” means that high-density polyethylene resin and polystyrene resin are present in the particles.

（１）高密度ポリエチレン系樹脂
高密度ポリエチレン系樹脂は、９３５〜９６０ｋｇ／ｍ３の密度を有する。
高密度ポリエチレン系樹脂の密度が９３５ｋｇ／ｍ３未満の場合、発泡成形体の衝撃吸収性が低下することがある。９６０ｋｇ／ｍ３より高い場合、重合工程時に樹脂成分が十分に軟化せず、複合樹脂粒子に由来する発泡性粒子が十分な発泡性を有さないことがある。密度は９３５〜９５０ｋｇ／ｍ３であることが好ましく、９３５〜９４０ｋｇ／ｍ３であることがより好ましい。
高密度ポリエチレン系樹脂は、１６０℃における溶融張力が４０ｍＮ以上であり、ＭＦＲが２．５ｇ／１０分以下であることが好ましい。
また、高密度ポリエチレン系樹脂は、エチレンと炭素数３〜８のα−オレフィンの共重合体であることが好ましい。高密度ポリエチレン系樹脂には、市販品を使用できる。市販品としては、例えば、ＴＯＳＯＨ−ＨＭＳ １０Ｓ６５Ｂ（東ソー社製）、ノバテックＨＤ ＨＹ５４０（日本ポリエチレン社製）等が挙げられる。
なお、例えばニポロンＺ ＺＦ２６０（東ソー社製）やニポロンＬ Ｍ５０（東ソー社製）等の密度９３５ｋｇ／ｍ３以上の直鎖状低密度ポリエチレン系樹脂が市販されているが、高密度ポリエチレン系樹脂に代えて、この直鎖状低密度ポリエチレン系樹脂を使用したとしても、機械強度及び耐熱性が十分改善された発泡成形体を成形加工性よく製造可能な複合樹脂粒子を得ることはできない。 (1) high density polyethylene resin density polyethylene resin has a density of 935~960kg / m 3.
When the density of the high-density polyethylene resin is less than 935 kg / m 3 , the shock absorption of the foamed molded article may be reduced. When it is higher than 960 kg / m 3 , the resin component does not sufficiently soften during the polymerization step, and the expandable particles derived from the composite resin particles may not have sufficient expandability. Preferably the density is 935~950kg / m 3, more preferably 935~940kg / m 3.
The high-density polyethylene resin preferably has a melt tension at 160 ° C. of 40 mN or more and an MFR of 2.5 g / 10 minutes or less.
Further, the high-density polyethylene resin is preferably a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms. Commercial products can be used for the high-density polyethylene resin. Examples of commercially available products include TOSOH-HMS 10S65B (manufactured by Tosoh Corporation) and Novatec HD HY540 (manufactured by Nippon Polyethylene Corporation).
Note that linear low-density polyethylene resins having a density of 935 kg / m 3 or more such as Nipolon Z ZF260 (manufactured by Tosoh Corporation) and Nipolon LM50 (manufactured by Tosoh Corporation) are commercially available. Instead, even if this linear low-density polyethylene resin is used, it is not possible to obtain composite resin particles capable of producing a foamed molded article having sufficiently improved mechanical strength and heat resistance with good moldability.

（２）カルボニル基を有するエチレン系共重合体
カルボニル基を有するエチレン系共重合体（以下、エチレン系共重合体ともいう）は、上記ポリエチレン系樹脂を含まない。カルボニル基を有するエチレン系共重合体としては、エチレン酢酸ビニル共重合体、エチレン−アクリル酸共重合体、エチレン−アクリル酸アルキルエステル共重合体、エチレン−メタクリル酸共重合体、エチレン−メタクリル酸アルキルエステル共重合体等が挙げられる。エチレン系共重合体は、エチレン酢酸ビニル共重合体が好ましい。エチレン酢酸ビニル共重合体は、酢酸ビニル由来成分を１〜２０質量％含むことが好ましい。酢酸ビニル由来成分の含有量が、１質量％未満の場合、発泡成形性が悪化し十分な成型加工性の向上効果が期待できないことがある。２０質量％より多い場合、発泡成形体の強度が低下し十分な衝撃吸収性が付与できないことがある。含有量は、５〜１５質量％であることが好ましく、８〜１２質量％であることがより好ましい。 (2) Ethylene-based copolymer having a carbonyl group An ethylene-based copolymer having a carbonyl group (hereinafter also referred to as an ethylene-based copolymer) does not include the above-mentioned polyethylene-based resin. Examples of the ethylene-based copolymer having a carbonyl group include ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid alkyl ester copolymer, ethylene-methacrylic acid copolymer, ethylene-alkyl methacrylate Ester copolymers and the like can be mentioned. The ethylene-based copolymer is preferably an ethylene-vinyl acetate copolymer. The ethylene-vinyl acetate copolymer preferably contains 1 to 20% by mass of a component derived from vinyl acetate. When the content of the component derived from vinyl acetate is less than 1% by mass, the foaming moldability deteriorates, and a sufficient effect of improving the moldability may not be expected. When the amount is more than 20% by mass, the strength of the foamed molded article is reduced, and sufficient impact absorption may not be provided. The content is preferably from 5 to 15% by mass, and more preferably from 8 to 12% by mass.

（３）ポリスチレン系樹脂
ポリスチレン系樹脂としては、スチレン単独重合体、又はスチレン単量体を主成分とし、スチレン単量体と共重合可能な他の単量体成分との共重合体等が挙げられる。ここで、主成分とは、スチレン単量体が全単量体成分１００質量部中に５０質量部以上、好ましくは６０質量部以上、より好ましくは７０質量部以上を占めることを意味する。
ポリスチレン系樹脂中に含まれる共重合体成分を与える他の単量体としては、所望の物性に影響を与えない限り、公知の単量体を使用できる。具体的には、環状オレフィン系単量体、ジエン系単量体、塩化ビニル、塩化ビニリデン、アクリロニトリル、酢酸ビニル、アクリル酸、メタクリル酸、マレイン酸、アクリル酸エチル、アクリル酸ブチル、メタクリル酸メチル、無水マレイン酸及びメチルスチレンのようなビニル系単量体を挙げることができる。また、これらは１種又は２種以上で使用できる。 (3) Polystyrene-based resin Examples of the polystyrene-based resin include a styrene homopolymer or a copolymer of a styrene monomer as a main component and another monomer component copolymerizable with the styrene monomer. Can be Here, the main component means that the styrene monomer accounts for 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more based on 100 parts by mass of all the monomer components.
As the other monomer that gives the copolymer component contained in the polystyrene resin, a known monomer can be used as long as it does not affect desired physical properties. Specifically, cyclic olefin monomers, diene monomers, vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, ethyl acrylate, butyl acrylate, methyl methacrylate, Examples include vinyl monomers such as maleic anhydride and methylstyrene. These can be used alone or in combination of two or more.

（４）高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂との含有割合
複合樹脂粒子は、高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂とを、高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体の合計量／ポリスチレン系樹脂＝５／９５〜４０／６０の質量比で含む。合計量の質量比が５未満の場合、得られる発泡成形体の機械強度が低下することがある。４０より多い場合、得られる発泡粒子の発泡成形可能期間が短くなることがある。質量比は、１０／９０〜４０／６０であることが好ましく、１５／８５〜３５／６５であることがより好ましい。
複合樹脂粒子は、高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とを、高密度ポリエチレン系樹脂／カルボニル基を有するエチレン系共重合体＝５／９５〜５０／５０の質量比で含む。高密度ポリエチレン系樹脂の質量比が５未満の場合、耐熱性が低下することがある。５０より多い場合、発泡成形性が低下することがある。質量比は、２０／８０〜４５／５５であることがより好ましく、３０／７０〜４０／６０であることが更に好ましい。 (4) Content ratio of high-density polyethylene resin, ethylene copolymer having carbonyl group and polystyrene resin Composite resin particles are made of high-density polyethylene resin, ethylene copolymer having carbonyl group and polystyrene resin. Is contained in a mass ratio of the total amount of the high-density polyethylene resin and the ethylene copolymer having a carbonyl group / the polystyrene resin = 5/95 to 40/60. When the mass ratio of the total amount is less than 5, the mechanical strength of the obtained foam molded article may decrease. When it is more than 40, the foamable period of the obtained foamed particles may be short. The mass ratio is preferably from 10/90 to 40/60, and more preferably from 15/85 to 35/65.
The composite resin particles are obtained by mixing a high-density polyethylene resin and an ethylene copolymer having a carbonyl group with a mass ratio of 5/95 to 50/50 of the high-density polyethylene resin / ethylene copolymer having a carbonyl group. Including. When the mass ratio of the high-density polyethylene resin is less than 5, heat resistance may be reduced. If it is more than 50, the foam moldability may be reduced. The mass ratio is more preferably from 20/80 to 45/55, and even more preferably from 30/70 to 40/60.

（５）吸光度比（Ｄ６９８／Ｄ２８５０）
（ａ）複合樹脂粒子の表面吸光度比Ｄ１（Ｄ６９８／Ｄ２８５０）
複合樹脂粒子の表面は、０．５〜２．５の範囲の表面吸光度比Ｄ１（Ｄ６９８／Ｄ２８５０）を示す。Ｄ２８５０及びＤ６９８は、ＡＴＲ法により赤外分光分析することで得られる赤外線吸収スペクトルから算出された２８５０ｃｍ−１の吸光度（Ｄ２８５０）及び６９８ｃｍ−１の吸光度（Ｄ６９８）である。Ｄ６９８は、ポリスチレン系樹脂に含まれるベンゼン環の面外変角振動に由来する吸収スペクトルに対応する吸光度である。一方、Ｄ２８５０は、高密度ポリエチレン系樹脂とエチレン系共重合体とに含まれる−Ｃ−ＣＨ２炭化水素のＣＨ２の対称変角振動に由来する吸収スペクトルに対応する吸光度である。表面吸光度比が大きい場合、ポリスチレン系樹脂成分が多いことを意味し、小さい場合、少ないことを意味する。表面吸光度比が０．５未満の場合、得られる発泡成形体の機械強度が低下することがある。２．５より大きい場合、得られる発泡粒子の発泡成形可能期間が短くなることがある。表面吸光度比は、０．５〜２．２であることが好ましく、０．５〜２．０であることがより好ましく、１．０〜２．０であることが更に好ましい。 (5) Absorbance ratio (D698 / D2850)
(A) Surface absorbance ratio D1 of composite resin particles (D698 / D2850)
The surface of the composite resin particles exhibits a surface absorbance ratio D1 (D698 / D2850) in the range of 0.5 to 2.5. D2850 and D698 are the absorbance at 2850 cm -1 (D2850) and the absorbance at 698 cm -1 (D698) calculated from the infrared absorption spectrum obtained by performing infrared spectroscopic analysis by the ATR method. D698 is an absorbance corresponding to an absorption spectrum derived from out-of-plane bending vibration of a benzene ring contained in the polystyrene resin. On the other hand, D2850 is an absorbance corresponding to an absorption spectrum derived from symmetric bending vibration of CH 2 of —C—CH 2 hydrocarbon contained in the high-density polyethylene resin and the ethylene copolymer. When the surface absorbance ratio is large, it means that the polystyrene resin component is large, and when it is small, it is small. When the surface absorbance ratio is less than 0.5, the mechanical strength of the obtained foamed molded article may decrease. When it is larger than 2.5, the foamable period of the obtained foamed particles may be short. The surface absorbance ratio is preferably from 0.5 to 2.2, more preferably from 0.5 to 2.0, and even more preferably from 1.0 to 2.0.

（ｂ）発泡成形体の表面吸光度比Ｄ２（Ｄ６９８／Ｄ２８５０）とＤ１との比（Ｄ２／Ｄ１）
発泡成形体の表面吸光度比Ｄ２（Ｄ６９８／Ｄ２８５０）とＤ１との比（Ｄ２／Ｄ１）は、０．１〜０．９５を示す。この比の範囲は、複合樹脂粒子の表面より、それから得られる発泡成形体の表面のポリスチレン系樹脂成分が少ないことを意味する。
ところで、実施例にも記載しているが、本明細書において、「表面」とは、ＡＴＲ法により赤外線吸収スペクトルを測定可能な試料の約数μｍまでの深さの領域を意味している。ここで、赤外線吸収スペクトルが測定された複合樹脂粒子の深さをＸ１、発泡成形体の測定深さが対応する複合樹脂粒子の深さをＸ２とすると、Ｘ１＞Ｘ２の関係となる。これは、発泡成形体が、複合樹脂粒子を大きく発泡させた発泡粒子の融着体から構成されるためである。従って、発泡成形体の表面の吸光度比は、複合樹脂粒子の表面の吸光度比より、複合樹脂粒子の浅い領域の表面を測定していることになる。上記Ｄ１とＤ２／Ｄ１の範囲は、複合樹脂粒子の表面から深さＸ１の領域は、ポリスチレン系樹脂成分がより多くなっている。言い換えると、複合樹脂粒子は、最も表面に近い領域で、若干ポリスチレン系樹脂成分を多く含んでいることになる。このようなポリスチレン系樹脂成分の存在量の関係を有する複合樹脂粒子が、機械強度及び耐熱性が改善された発泡成形体を成形加工性よく製造可能であることは意外であると発明者は考えている。
更に言えば、本発明の複合樹脂粒子は、エチレン系共重合体を比較的多く含んでいる。このような複合樹脂粒子であっても、上記Ｄ１とＤ２／Ｄ１の範囲を満たすことで、機械強度及び耐熱性が改善された発泡成形体を成形加工性よく製造可能である。
Ｄ２／Ｄ１が、０．１未満の場合、発泡性が低下することがある。０．９５より大きい場合、機械強度や耐熱性が期待された効果ほど得られないことがある。Ｄ２／Ｄ１は、０．２〜０．９であることが好ましく、０．３〜０．９であることがより好ましい。
また、Ｄ２は、０．５〜２．５であることが好ましく、０．５〜２．０であることがより好ましく、０．５〜１．５であることが更に好ましい。 (B) The ratio of the surface absorbance ratio D2 (D698 / D2850) of the foam molded article to D1 (D2 / D1)
The ratio (D2 / D1) of the surface absorbance ratio D2 (D698 / D2850) and D1 of the foamed molded product is 0.1 to 0.95. This range of the ratio means that the polystyrene resin component on the surface of the foamed article obtained therefrom is smaller than the surface of the composite resin particle.
By the way, as described in Examples, in this specification, "surface" means a region of a sample in which an infrared absorption spectrum can be measured by the ATR method up to a depth of about several μm. Here, if the depth of the composite resin particle whose infrared absorption spectrum is measured is X1, and the depth of the composite resin particle corresponding to the measured depth of the foam molded product is X2, the relationship X1> X2 is satisfied. This is because the foamed molded article is composed of a fused body of foamed particles obtained by greatly foaming the composite resin particles. Therefore, the absorbance ratio of the surface of the foamed molded article is measured on the surface of the shallow region of the composite resin particle from the absorbance ratio of the surface of the composite resin particle. In the range of D1 and D2 / D1, the region of the depth X1 from the surface of the composite resin particle has more polystyrene resin component. In other words, the composite resin particles contain a little polystyrene resin component in the region closest to the surface. The inventor considers that it is surprising that such composite resin particles having the relationship of the abundance of the polystyrene resin component can produce a foamed molded article having improved mechanical strength and heat resistance with good moldability. ing.
Furthermore, the composite resin particles of the present invention contain a relatively large amount of an ethylene-based copolymer. Even with such composite resin particles, by satisfying the range of D1 and D2 / D1, a foamed molded article having improved mechanical strength and heat resistance can be manufactured with good moldability.
When D2 / D1 is less than 0.1, foamability may be reduced. When it is larger than 0.95, mechanical strength and heat resistance may not be obtained as expected. D2 / D1 is preferably 0.2 to 0.9, and more preferably 0.3 to 0.9.
D2 is preferably from 0.5 to 2.5, more preferably from 0.5 to 2.0, and even more preferably from 0.5 to 1.5.

（６）他の成分
他の成分としては、ポリエチレン系樹脂とエチレン系共重合体とポリスチレン系樹脂以外の樹脂（例えば、ポリプロピレン系樹脂、アクリル系樹脂）や、気泡調整剤、被覆剤、光安定剤、紫外線吸収剤、顔料、染料、消泡剤、熱安定剤、難燃剤、滑剤及び帯電防止剤を挙げることができる。
（７）形状
複合樹脂粒子の形状は球状〜略球状であることが好ましい。その平均粒子径は０．７１〜２．５ｍｍが好ましく、０．８５〜１．６ｍｍがより好ましい。 (6) Other components Other components include resins other than polyethylene resins, ethylene copolymers and polystyrene resins (for example, polypropylene resins and acrylic resins), bubble regulators, coating agents, and light stability. Agents, ultraviolet absorbers, pigments, dyes, defoamers, heat stabilizers, flame retardants, lubricants and antistatic agents.
(7) Shape The shape of the composite resin particles is preferably spherical to approximately spherical. The average particle diameter is preferably from 0.71 to 2.5 mm, more preferably from 0.85 to 1.6 mm.

（複合樹脂粒子の製造方法）
複合樹脂粒子の製造方法としては、上で説明した複合樹脂粒子を得ることができさえすれば、特に限定されない。一例として、以下の製造方法により複合樹脂粒子を得ることができる。
即ち、高密度ポリエチレン系樹脂とエチレン系共重合体とを含む種粒子に含浸させたスチレン系モノマーを重合することにより複合樹脂粒子を得ることができる。この方法は、所謂、シード重合法である。シード重合法によれば、ポリエチレン系樹脂とエチレン系共重合体とが粒子表面に偏在した複合樹脂粒子を得ることができる。 (Method for producing composite resin particles)
The method for producing the composite resin particles is not particularly limited as long as the composite resin particles described above can be obtained. As an example, composite resin particles can be obtained by the following production method.
That is, composite resin particles can be obtained by polymerizing a styrene-based monomer impregnated into seed particles containing a high-density polyethylene-based resin and an ethylene-based copolymer. This method is a so-called seed polymerization method. According to the seed polymerization method, it is possible to obtain composite resin particles in which a polyethylene resin and an ethylene copolymer are unevenly distributed on the particle surface.

より具体的な複合樹脂粒子の製造方法の一例を下記する。
まず、水性懸濁液中に、高密度ポリエチレン系樹脂とエチレン系共重合体とを含む種粒子と、スチレン系単量体と、重合開始剤とを分散させる。なお、スチレン系単量体と重合開始剤とを予め混合して用いてもよい。
種粒子は、公知の方法により得ることができる。例えば、高密度ポリエチレン系樹脂とエチレン系共重合体とを、必要に応じて添加剤（例えば、無機核剤）と共に、押出機中で溶融混練して押出すことでストランドを得、得られたストランドを、空気中でカット、水中でカット、加熱しつつカットすることで、造粒する方法が挙げられる。
また前記種粒子は、１１０〜１３０℃の軟化温度を有していることが好ましい。種粒子の軟化温度が１１０℃未満の場合、十分な加熱寸法安定性を有さないことがある。種粒子の軟化温度が１３５℃より高い場合、発泡成形性が悪く、生産性が悪化することがある。種粒子の軟化温度は１１４〜１３０℃であることが好ましく、１１６〜１２８℃であることがより好ましい。 An example of a more specific method for producing composite resin particles will be described below.
First, seed particles containing a high-density polyethylene-based resin and an ethylene-based copolymer, a styrene-based monomer, and a polymerization initiator are dispersed in an aqueous suspension. In addition, you may mix and use a styrene-type monomer and a polymerization initiator beforehand.
Seed particles can be obtained by a known method. For example, a strand was obtained by melt-kneading and extruding a high-density polyethylene-based resin and an ethylene-based copolymer together with an additive (for example, an inorganic nucleating agent) as necessary, in an extruder to obtain a strand. A method of granulating the strand by cutting the strand in the air, cutting in water, and cutting while heating may be used.
Preferably, the seed particles have a softening temperature of 110 to 130 ° C. When the softening temperature of the seed particles is lower than 110 ° C., sufficient heat dimensional stability may not be obtained. When the softening temperature of the seed particles is higher than 135 ° C., the foam moldability is poor, and the productivity may be deteriorated. The softening temperature of the seed particles is preferably from 114 to 130 ° C, more preferably from 116 to 128 ° C.

重合開始剤としては、一般にスチレン系単量体の懸濁重合用の開始剤として用いられているものが使用できる。例えば、ベンゾイルパーオキサイド、ジ−ｔ−ブチルパーオキサイド、ｔ−ブチルパーオキシベンゾエート、ジクミルパーオキサイド、２，５−ジメチル−２，５−ジ−ｔ−ブチルパーオキシヘキサン、ｔ−ブチルパーオキシ−３，５，５−トリメチルヘキサノエート、ｔ−ブチル−パーオキシ−２−エチルヘキシルカーボネート等の有機化過酸化物である。これらの重合開始剤は１種又は２種以上を使用できる。
水性懸濁液を構成する水性媒体としては、水、水と水溶性溶媒（例えば、低級アルコール）との混合媒体が挙げられる。 As the polymerization initiator, those generally used as an initiator for suspension polymerization of a styrene monomer can be used. For example, benzoyl peroxide, di-t-butyl peroxide, t-butylperoxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, t-butylperoxy Organic peroxides such as -3,5,5-trimethylhexanoate and t-butyl-peroxy-2-ethylhexyl carbonate. One or two or more of these polymerization initiators can be used.
Examples of the aqueous medium constituting the aqueous suspension include water and a mixed medium of water and a water-soluble solvent (for example, a lower alcohol).

重合開始剤の使用量は、スチレン系単量体１００質量部に対して、０．１〜０．９質量部が好ましく、０．２〜０．５質量部がより好ましい。重合開始剤の使用量が０．１質量部未満ではスチレン系単量体の重合に時間がかかり過ぎることがある。重合開始剤の使用量が０．９質量部を超えると、ポリスチレン系樹脂の分子量が低くなることがある。
水性懸濁液には、必要に応じて分散剤を添加してもよい。分散剤としては、特に限定されず、公知のものをいずれも使用できる。具体的には、リン酸カルシウム、ピロリン酸マグネシウム、ピロリン酸ナトリウム、酸化マグネシウム等の難溶性無機物が挙げられる。更に、ドデシルベンゼンスルホン酸ナトリウムのような界面活性剤を使用してもよい。 The amount of the polymerization initiator to be used is preferably 0.1 to 0.9 part by mass, more preferably 0.2 to 0.5 part by mass, based on 100 parts by mass of the styrene monomer. If the amount of the polymerization initiator is less than 0.1 part by mass, the polymerization of the styrene monomer may take too long. If the amount of the polymerization initiator exceeds 0.9 parts by mass, the molecular weight of the polystyrene resin may be low.
A dispersant may be added to the aqueous suspension as needed. The dispersant is not particularly limited, and any known dispersant can be used. Specific examples include poorly soluble inorganic substances such as calcium phosphate, magnesium pyrophosphate, sodium pyrophosphate, and magnesium oxide. Further, a surfactant such as sodium dodecylbenzenesulfonate may be used.

次に、得られた分散液をスチレン系単量体が実質的に重合しない温度に加熱してスチレン系単量体を種粒子に含浸させる。種粒子内部にスチレン系単量体を含浸させる時間は、３０分〜２時間が適当である。十分に含浸させる前に重合が進行するとポリスチレン系樹脂の重合体粉末を生成してしまうことがある。単量体が実質的に重合しない温度とは、高い方が含浸速度を速めるには有利であるが、重合開始剤の分解温度を考慮して決定する必要がある。
次いで、スチレン系単量体の重合を行う。重合は、特に限定されないが、１１５〜１４０℃で、１．５〜５時間行うことが好ましい。重合は、通常、加圧可能な密閉容器中で行われる。なお、スチレン系単量体の含浸と重合を複数回に分けて行ってもよい。複数回に分けることで、スチレン系樹脂の重合体粉末の発生を極力少なくできる。また、重合開始剤の分解温度を考慮して、スチレン系単量体を種粒子に含浸させてからではなく、スチレン系単量体を含浸させながら重合を行ってもよい。
上記方法により複合樹脂粒子を得ることができる。 Next, the resulting dispersion is heated to a temperature at which the styrene-based monomer is not substantially polymerized, so that the styrene-based monomer is impregnated into the seed particles. The time for impregnating the seed particles with the styrene monomer is preferably 30 minutes to 2 hours. If the polymerization proceeds before sufficient impregnation, a polymer powder of a polystyrene resin may be formed. The higher the temperature at which the monomer does not substantially polymerize is advantageous for increasing the impregnation rate, but it must be determined in consideration of the decomposition temperature of the polymerization initiator.
Next, the styrene monomer is polymerized. The polymerization is not particularly limited, but is preferably performed at 115 to 140 ° C. for 1.5 to 5 hours. The polymerization is usually performed in a pressurized closed container. In addition, impregnation and polymerization of the styrene-based monomer may be performed in plural times. By dividing into a plurality of times, the generation of the polymer powder of the styrene resin can be minimized. In addition, in consideration of the decomposition temperature of the polymerization initiator, the polymerization may be performed not while the seed particles are impregnated with the styrene monomer but while the styrene monomer is impregnated.
Composite resin particles can be obtained by the above method.

好ましい複合樹脂粒子の製造方法としては、スチレン系単量体の含浸と重合を２回に分け、１回目の含浸時において、スチレン系単量体の投入後、重合前に、特定の温度でスチレン系単量体を種粒子に吸収させる工程を含む方法が挙げられる。この好ましい製造方法に使用される種粒子は、種粒子のＤＳＣ曲線に少なくとも２つ以上の融解ピーク温度（高温側をＴ１、低温側をＴ２）を有するものが好ましい。特定の温度範囲は、Ｔ１とＴ２の温度範囲内である。また、この好ましい製造方法に使用される種粒子は、種粒子のＤＳＣ曲線に少なくとも２つ以上の融解ピーク温度（高温側をＴ１、低温側をＴ２）を有し、ＴＭＡ曲線で規定される軟化温度Ｔ３を有するものがより好ましい。特定の温度範囲は、Ｔ３とＴ１の温度範囲内であってもよい。特定の温度でスチレン系単量体を種粒子に吸収させる工程は、更に好ましくは使用される種粒子のＴＭＡ曲線で規定される軟化温度Ｔ３以上の温度であり、かつ使用する重合開始剤の１０時間半減期温度Ｔ１０℃〜Ｔ１０＋５℃の温度範囲内で行うことが好ましく、またスチレン系単量体を種粒子に吸収させる工程は、使用される重合開始剤の分解率が１０〜２０％に達する時間行うことが好ましい。更に、特定の温度でスチレン系単量体を種粒子に吸収させた場合、１回目の重合温度は、Ｔ２〜Ｔ１＋１０℃の範囲内であることが好ましい。
加えて、２回目の重合工程において、スチレン系単量体は、種粒子１００質量部に対して１．５質量部／分以下の速度で投入しつつ重合を行うことが好ましい。 As a preferred method for producing composite resin particles, the impregnation and polymerization of the styrene-based monomer are divided into two times, and during the first impregnation, the styrene-based monomer is charged at a specific temperature before the polymerization and before the polymerization. A method including a step of absorbing the system monomer into the seed particles is exemplified. The seed particles used in this preferred production method preferably have at least two or more melting peak temperatures (T1 on the high temperature side and T2 on the low temperature side) in the DSC curve of the seed particles. The specific temperature range is within the temperature range of T1 and T2. The seed particles used in this preferred production method have at least two or more melting peak temperatures (T1 on the high temperature side and T2 on the low temperature side) in the DSC curve of the seed particles, and have a softening point defined by the TMA curve. Those having a temperature T3 are more preferred. The particular temperature range may be within the temperature range of T3 and T1. The step of causing the seed particles to absorb the styrene-based monomer at a specific temperature is more preferably a temperature equal to or higher than the softening temperature T3 defined by the TMA curve of the seed particles used, and 10 The half-life time is preferably performed within a temperature range of T10 ° C. to T10 + 5 ° C. In the step of absorbing the styrene-based monomer into the seed particles, the decomposition rate of the polymerization initiator used reaches 10 to 20%. It is preferable to carry out for a time. Furthermore, when the styrene-based monomer is absorbed by the seed particles at a specific temperature, the first polymerization temperature is preferably in the range of T2 to T1 + 10 ° C.
In addition, in the second polymerization step, it is preferable to perform the polymerization while introducing the styrene-based monomer at a rate of 1.5 parts by mass / minute or less based on 100 parts by weight of the seed particles.

（発泡性粒子）
発泡性粒子は、上記複合樹脂粒子と、発泡剤とを含む。
発泡剤としては揮発性を有する公知の発泡剤を使用できる。例えば、プロパン、ｎ−ブタン（ノルマルブタン）、ｉ−ブタン（イソブタン）、ｎ−ペンタン（ノルマルペンタン）、ｉ−ペンタン（イソペンタン）、ｎ−ヘキサン（ノルマルヘキサン）及びｉ−ヘキサン（イソヘキサン）の単独又はそれらの混合物を挙げられる。これらの内、より大きな発泡性能を発泡性粒子に導入できる、ｎ−ブタン、ｉ−ブタン、ｎ−ペンタン、ｉ−ペンタンのいずれかが好ましい。発泡剤は単独で用いてもよく２種以上を使用してもよい。 (Expandable particles)
The expandable particles include the composite resin particles and a foaming agent.
As the foaming agent, a known foaming agent having volatility can be used. For example, propane, n-butane (normal butane), i-butane (isobutane), n-pentane (normal pentane), i-pentane (isopentane), n-hexane (normal hexane) and i-hexane (isohexane) alone Or a mixture thereof. Among these, any of n-butane, i-butane, n-pentane, and i-pentane, which can introduce greater foaming performance into the expandable particles, is preferable. The blowing agents may be used alone or in combination of two or more.

発泡剤の含有量は、複合樹脂粒子１００質量部に対して、好ましくは５〜２０質量部、より好ましくは８〜１７質量部である。発泡剤の含有量が５質量部より低い場合、発泡剤量が不足し、発泡性粒子は十分な発泡性を有さないことがある。他方、発泡剤の含有量が２０質量部より多い場合、発泡剤量が過剰となり、この場合も、発泡性粒子は十分な発泡性を有さないことがある。
発泡性粒子の形状は球状〜略球状であることが好ましい。その平均粒子径は０．７１〜２．５ｍｍが好ましく、０．８５〜１．６ｍｍがより好ましい。 The content of the foaming agent is preferably 5 to 20 parts by mass, more preferably 8 to 17 parts by mass, based on 100 parts by mass of the composite resin particles. When the content of the blowing agent is lower than 5 parts by mass, the amount of the blowing agent is insufficient, and the expandable particles may not have sufficient expandability. On the other hand, when the content of the foaming agent is more than 20 parts by mass, the amount of the foaming agent becomes excessive, and also in this case, the expandable particles may not have sufficient expandability.
The shape of the expandable particles is preferably spherical to approximately spherical. The average particle diameter is preferably from 0.71 to 2.5 mm, more preferably from 0.85 to 1.6 mm.

発泡性粒子は、重合中もしくは重合終了後の複合樹脂粒子に発泡剤を含浸することで得ることができる。含浸は、それ自体公知の方法により行うことができる。例えば、重合中での含浸は、重合反応を密閉式の容器中で行い、容器中に発泡剤を圧入することにより行うことができる。重合終了後の含浸は、密閉式の容器中で、発泡剤を圧入することにより行われる。   The expandable particles can be obtained by impregnating the composite resin particles during or after the polymerization with a blowing agent. The impregnation can be performed by a method known per se. For example, the impregnation during the polymerization can be performed by performing the polymerization reaction in a closed container and pressing a foaming agent into the container. Impregnation after the completion of the polymerization is performed by press-fitting a foaming agent in a closed vessel.

（発泡粒子）
発泡粒子は、上記発泡性粒子を発泡（予備発泡とも称する）させて得られた粒子である。
発泡粒子は、好ましくは２０〜１００ｋｇ／ｍ３、より好ましくは２５〜１００ｋｇ／ｍ３の嵩密度を有する。嵩密度が２０ｋｇ／ｍ３より低いと、得られる発泡成形体の機械特性が低下することがある。一方、嵩密度が１００ｋｇ／ｍ３より高いと、得られる発泡成形体の質量が増加することがある。
発泡粒子の形状は球状〜略球状であることが好ましい。その平均粒子径は、１．０〜９．０ｍｍであることが好ましく、２．０〜６．４ｍｍであることがより好ましい。 (Expanded particles)
The expanded particles are particles obtained by expanding (also referred to as pre-expanding) the expandable particles.
Foam particles, preferably 20 and 100 kg / m 3, more preferably having a bulk density of 25~100kg / m 3. If the bulk density is lower than 20 kg / m 3 , the mechanical properties of the obtained foamed molded article may be reduced. On the other hand, if the bulk density is higher than 100 kg / m 3 , the mass of the obtained foamed molded article may increase.
The shape of the expanded particles is preferably spherical to approximately spherical. The average particle size is preferably from 1.0 to 9.0 mm, and more preferably from 2.0 to 6.4 mm.

発泡粒子は、発泡性粒子を、公知の方法で所定の嵩密度に発泡させることで得ることができる。発泡は、好ましくは０．０５〜０．２０ＭＰａ（ゲージ圧）、より好ましくは０．０６〜０．１５ＭＰａの加熱蒸気を使用して発泡性粒子を発泡させることにより得ることができる。   The expanded particles can be obtained by expanding the expandable particles to a predetermined bulk density by a known method. Foaming can be obtained by foaming the expandable particles using heated steam of preferably 0.05 to 0.20 MPa (gauge pressure), more preferably 0.06 to 0.15 MPa.

（発泡成形体）
発泡成形体は、上記発泡粒子を発泡成形させて得られ、発泡粒子の融着体から構成された発泡体である。発泡成形体は、上記複合樹脂粒子を原料として使用するため、優れた機械特性を有する。
発泡成形体の密度は、２０〜１００ｋｇ／ｍ３であることが好ましく、２５〜１００ｋｇ／ｍ３であることがより好ましい。
発泡成形体は、発泡粒子を発泡成形機の金型内に充填し、再度加熱して発泡粒子を発泡させながら、発泡粒子同士を熱融着させることで得ることができる。加熱用の媒体は水蒸気が好適に使用できる。
各製造工程における工程温度、工程圧力及び工程時間のようなその他の製造条件は、使用する製造設備、原料等に従って適宜設定される。
発泡成形体は、自動車部材、部品梱包材及び緩衝材に使用できる。 (Foam molding)
The foam molded article is a foam obtained by subjecting the above-described foam particles to foam molding, and constituted by a fused body of the foam particles. Since the foamed molded article uses the composite resin particles as a raw material, it has excellent mechanical properties.
The density of the foamed molded article is preferably 20 and 100 kg / m 3, more preferably 25~100kg / m 3.
The foamed molded article can be obtained by filling the foamed particles into a mold of a foaming molding machine and heat-sealing the foamed particles while heating again to foam the foamed particles. Steam can be suitably used as the heating medium.
Other manufacturing conditions such as a process temperature, a process pressure, and a process time in each manufacturing process are appropriately set according to a used manufacturing facility, raw materials, and the like.
The foam molded article can be used for an automobile member, a component packaging material, and a cushioning material.

以下、実施例及び比較例により本発明を具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
（高密度ポリエチレン系樹脂の密度）
高密度ポリエチレン系樹脂の密度は、ＪＩＳ Ｋ６９２２−１：１９９８に準拠して密度勾配管法で測定した。
（高密度ポリエチレン系樹脂のメルトフローレート（ＭＦＲ））
ＭＦＲは、ＪＩＳ Ｋ６９２２−１：１９９８に準拠して、１９０℃、２．１６ｋｇの荷重下で測定した。 Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
(Density of high density polyethylene resin)
The density of the high-density polyethylene resin was measured by a density gradient tube method in accordance with JIS K692-1: 1998.
(Melt flow rate (MFR) of high density polyethylene resin)
The MFR was measured at 190 ° C. under a load of 2.16 kg in accordance with JIS K6922-1: 1998.

（高密度ポリエチレン系樹脂の融点）
融点は、ＪＩＳ Ｋ７１２２：１９８７「プラスチックの転移熱測定方法」記載の方法により測定した。即ち、示差走査熱量計装置ＲＤＣ２２０型（セイコー電子工業社製）を用い、測定容器に試料を７ｍｇ充填して、窒素ガス流量３０ｍＬ／分のもと、室温から２２０℃の間で１０℃／Ｌの昇、降温スピードにより昇温、降温、昇温を繰り返し、２回目の昇温時のＤＳＣ曲線の融解ピーク温度を測定した。この融解ピーク温度を融点とした。また、融解ピークが２つ以上ある場合は、低い側のピーク温度を融点とした。 (Melting point of high density polyethylene resin)
The melting point was measured by the method described in JIS K7122: 1987 “Method of measuring heat of transition of plastic”. That is, using a differential scanning calorimeter apparatus RDC220 type (manufactured by Seiko Denshi Kogyo), 7 mg of a sample is filled in a measuring container, and 10 ° C./L between room temperature and 220 ° C. under a nitrogen gas flow rate of 30 mL / min. The heating, cooling, and heating were repeated at the heating and cooling speeds, and the melting peak temperature of the DSC curve during the second heating was measured. This melting peak temperature was defined as the melting point. When there were two or more melting peaks, the lower peak temperature was defined as the melting point.

（溶融張力（１６０℃）の測定）
ポリオレフィン系樹脂に、耐熱安定剤（チバスペシャリティケミカルズ社製、イルガノックス１０１０ＴＭ；１５００ｐｐｍ、イルガフォス１６８ＴＭ；１５００ｐｐｍ）を添加したものを、インターナルミキサー（東洋精機製作所社製、商品名ラボプラストミル）を用いて、窒素気流下、１９０℃、回転数３０ｒｐｍで３０分間混練したもの測定用試料とした。
バレル直径９．５５ｍｍの毛管粘度計（東洋精機制作所社製、商品名キャピログラフ）に、長さが８ｍｍ、直径が２．０９５ｍｍのダイス状の試料を流入角が９０°になるように装着して溶融張力を測定した。
１６０℃での溶融張力は温度を１６０℃に設定し、ピストン降下速度を１０ｍｍ／分、延伸比を４７に設定し、引き取りに必要な荷重（ｍＮ）とした。なお、最大延伸比が４７未満の場合、破断しない最高の延伸比での引き取りに必要な荷重（ｍＮ）とした。 (Measurement of melt tension (160 ° C))
A heat-resistant stabilizer (Irganox 1010TM; 1500 ppm, Irgafos 168TM; 1500 ppm, manufactured by Ciba Specialty Chemicals) added to a polyolefin-based resin was used with an internal mixer (manufactured by Toyo Seiki Seisakusho Co., Ltd., trade name: Labo Plastomill). The mixture was kneaded under a nitrogen stream at 190 ° C. and a rotation speed of 30 rpm for 30 minutes to obtain a measurement sample.
A dice-like sample having a length of 8 mm and a diameter of 2.095 mm was attached to a capillary viscometer having a barrel diameter of 9.55 mm (manufactured by Toyo Seiki Seisakusho Co., Ltd., so that the inflow angle was 90 °). The melt tension was measured.
Regarding the melt tension at 160 ° C., the temperature was set to 160 ° C., the piston descending speed was set to 10 mm / min, the stretching ratio was set to 47, and the load (mN) required for take-up was set. When the maximum stretching ratio was less than 47, the load (mN) required for taking over at the highest stretching ratio that did not break was used.

（種粒子の融解ピーク温度）
融点は、ＪＩＳ Ｋ７１２２：１９８７「プラスチックの転移熱測定方法」に記載の方法により測定した。
すなわち、示差走査熱量計装置ＤＳＣ６２２０型（エスアイアイナノテクノロジー社製）を用い、アルミニウム製測定容器の底にすきまのないよう試料を約６ｍｇ充てんした。次いで、窒素ガス流量２０ｍＬ／ｍｉｎのもと、３０℃から−４０℃まで降温した後１０分間保持し、−４０℃から２２０℃まで昇温（１ｓｔ Ｈｅａｔｉｎｇ)、１０分間保持後２２０℃から−４０℃まで降温（Ｃｏｏｌｉｎｇ）、１０分間保持後−４０℃から２２０℃まで昇温（２ｎｄ Ｈｅａｔｉｎｇ)した時のＤＳＣ曲線を得た。なお、全ての昇温・降温は速度１０℃／ｍｉｎで行い、基準物質としてアルミナを用いた。
装置付属の解析ソフトを用いて、２ｎｄ Ｈｅａｔｉｎｇ過程にみられる融解ピークのトップの温度を読みとった値を融点とした。融解ピークが２つ以上ある場合、最も深いピークとその次に深いピークとを選択し、低い温度側のピークを融解ピーク温度Ｔ１（℃）と高い温度側のピークを融解ピーク温度Ｔ２（℃）とした。 (Melting peak temperature of seed particles)
The melting point was measured by the method described in JIS K7122: 1987 "Method for measuring heat of transition of plastic".
That is, using a differential scanning calorimeter apparatus DSC6220 type (manufactured by SII Nanotechnology Co., Ltd.), about 6 mg of the sample was filled in the bottom of the aluminum measuring container so that there was no gap. Next, under a nitrogen gas flow rate of 20 mL / min, the temperature was lowered from 30 ° C. to −40 ° C., held for 10 minutes, and then raised from −40 ° C. to 220 ° C. (1st Heating). A DSC curve was obtained when the temperature was lowered to (Cooling) for 10 minutes and then raised from -40 ° C to 220 ° C (2nd Heating) after holding for 10 minutes. In addition, all the temperature raising / lowering was performed at a rate of 10 ° C./min, and alumina was used as a reference substance.
The value obtained by reading the temperature at the top of the melting peak observed in the second heating process using analysis software attached to the apparatus was defined as the melting point. If there are two or more melting peaks, the deepest peak and the next deepest peak are selected, and the lower temperature side peak is the melting peak temperature T1 (° C) and the higher temperature side peak is the melting peak temperature T2 (° C). And

（エチレン系共重合体及び種粒子の軟化温度）
ＪＩＳ Ｋ７１９６:１９９１「熱可塑性プラスチックフィルム及びシートの熱機械分析による軟化温度試験方法」記載の方法に準拠し測定した。
すなわち、試料を１８０℃で５分間熱プレスして、厚み１ｍｍ、直径１０ｍｍの円盤プレート状試験片を作製する。熱・応力・歪み測定装置（エスアイアイ・ナノテクノロジー社製、商品名「ＥＸＳＴＲＡＲ ＴＭＡ／ＳＳ６１００」）を用い、窒素雰囲気下で針入試験モード（針の先端 φ１ｍｍ、石英製プローブ）、荷重５００ｍＮで、試験片に針を当てて、３０℃から昇温速度５℃／ｍｉｎで温度を上げていきＴＭＡ曲線を得た。得られたＴＭＡ曲線を装置付属の解析ソフトで石英係数設定による補正を行い、ＴＭＡ曲線の圧子（針）が侵入を始めるよりも低温側に認められる直線部分を高温側に延長し、侵入速度が最大となる部分の接線の低温側への延長との交点を針入温度とし、その針入温度をこの試料の軟化温度とした。 (Softening temperature of ethylene copolymer and seed particles)
The measurement was carried out according to the method described in JIS K7196: 1991 “Testing method for softening temperature of thermoplastic films and sheets by thermomechanical analysis”.
That is, the sample is hot-pressed at 180 ° C. for 5 minutes to produce a disk-shaped test piece having a thickness of 1 mm and a diameter of 10 mm. Using a heat / stress / strain measuring device (SII Nanotechnology Co., Ltd., trade name "EXSTRAR TMA / SS6100") under a nitrogen atmosphere in a penetration test mode (needle tip φ1 mm, quartz probe) at a load of 500 mN A needle was applied to the test piece, and the temperature was increased from 30 ° C. at a rate of temperature increase of 5 ° C./min to obtain a TMA curve. The obtained TMA curve is corrected by setting the quartz coefficient with the analysis software attached to the device, and the straight line portion of the TMA curve, which is recognized on the lower temperature side than the indenter (needle) starts to penetrate, is extended to the higher temperature side, and the penetration speed is reduced. The point of intersection of the tangent of the maximum portion with the extension to the lower temperature side was defined as the penetration temperature, and the penetration temperature was defined as the softening temperature of this sample.

（複合樹脂粒子の吸光度比（Ｄ６９８／Ｄ２８５０））
（ａ）表面の吸光度比（Ｄ６９８／Ｄ２８５０）を次の要領で測定した。
なお、赤外吸収スペクトルから得られる各吸光度は、複合樹脂粒子に含まれる各樹脂成分の振動に由来するピークの高さとした。
無作為に選択した１０個の粒子について、赤外分光分析ＡＴＲ測定法により粒子断面分析を行って赤外吸収スペクトルを得た。この分析では、試料表面から数μｍ（約２μｍ）までの深さの範囲の赤外吸収スペクトルが得られた。
各赤外吸収スペクトルから個別の吸光度比（Ｄ６９８／Ｄ２８５０）を算出し、それらの相加平均を吸光度比とした。
吸光度Ｄ６９８及びＤ２８５０は、Ｎｉｃｏｌｅｔ社から商品名「フーリエ変換赤外分光分析計 ＭＡＧＮＡ５６０」で販売されている測定装置と、ＡＴＲアクセサリーとしてＳｐｅｃｔｒａ−Ｔｅｃｈ社製「サンダードーム」を用いて次の条件で測定した。 (Absorbance ratio of composite resin particles (D698 / D2850))
(A) The surface absorbance ratio (D698 / D2850) was measured as follows.
In addition, each absorbance obtained from the infrared absorption spectrum was defined as a peak height derived from vibration of each resin component contained in the composite resin particles.
About 10 particles selected at random, the particle cross-section analysis was performed by the infrared spectroscopic analysis ATR measurement method, and the infrared absorption spectrum was obtained. In this analysis, an infrared absorption spectrum in a depth range from the sample surface to several μm (about 2 μm) was obtained.
An individual absorbance ratio (D698 / D2850) was calculated from each infrared absorption spectrum, and their arithmetic mean was defined as an absorbance ratio.
The absorbances D698 and D2850 are measured under the following conditions using a measuring device sold by Nicolet under the trade name “Fourier transform infrared spectrometer MAGNA560” and a “Thunderdome” manufactured by Spectra-Tech as an ATR accessory. did.

（１）測定条件
高屈折率結晶種：Ｇｅ（ゲルマニウム）
入射角：４５°±１°
測定領域：４０００ｃｍ−１〜６７５ｃｍ−１
測定深度の端数依存性：補正せず
反射回数：１回
検出器：ＤＴＧＳ ＫＢｒ
分解能：４ｃｍ−１
積算回数：３２回
その他：試料と接触させずに赤外線吸収スペクトルを下記の条件で測定し、測定されたスペクトルをバックグラウンドとした。試料の測定時には、バックグラウンドが測定スペクトルに関与しないように、測定データを処理した。ＡＴＲ法では、試料と高屈折率結晶の密着度合によって、赤外吸収スペクトルの強度が変化した。そのため、ＡＴＲアクセサリーの「サンダードーム」で掛けられる最大荷重を掛けて密着度合をほぼ均一にして測定を行った。 (1) Measurement conditions High refractive index crystal seed: Ge (germanium)
Incident angle: 45 ° ± 1 °
Measurement area: 4000 cm -1 to 675 cm -1
Fractional dependence of measurement depth: uncorrected Number of reflections: 1 Detector: DTGS KBr
Resolution: 4cm -1
Number of integration: 32 times Others: The infrared absorption spectrum was measured without contact with the sample under the following conditions, and the measured spectrum was used as the background. When measuring the sample, the measured data was processed so that the background did not contribute to the measured spectrum. In the ATR method, the intensity of the infrared absorption spectrum changed depending on the degree of adhesion between the sample and the high refractive index crystal. Therefore, the maximum load applied by the “Thunder Dome” of the ATR accessory was applied to make the degree of adhesion almost uniform, and the measurement was performed.

（２）バックグランド測定条件
モード：透過
ピクセルサイズ：６．２５μｍ
測定領域：４０００ｃｍ−１〜６５０ｃｍ−１
検出器：ＭＣＴ
分解能：８ｃｍ−１
スキャン／ピクセル：６０回
その他：試料近傍の試料のない部分のフッ化バリウム結晶を測定した赤外吸収スペクトルをバックグランドとして測定スペクトルに関与しない処理を実施した。 (2) Background measurement conditions Mode: Transmission Pixel size: 6.25 μm
Measurement area: 4000 cm -1 to 650 cm -1
Detector: MCT
Resolution: 8cm -1
Scan / pixel: 60 times Others: Processing not involving the measured spectrum was performed using the infrared absorption spectrum of the barium fluoride crystal in the vicinity of the sample where there was no sample as the background as the background.

以上の条件で得られた赤外線吸収スペクトルについて、次のようにピーク処理をしてそれぞれの吸光度を求めた。
赤外吸収スペクトルから得られる６９８ｃｍ−１での吸光度Ｄ６９８は、ポリスチレン系樹脂に含まれるベンゼン環の面外変角振動に由来する吸収スペクトルに対応する吸光度とした。この吸光度の測定では、６９８ｃｍ−１で他の吸収スペクトルが重なっている場合でもピーク分離を実施しなかった。吸光度Ｄ６９８は、２０００ｃｍ−１と８７０ｃｍ−１を結ぶ直線をベースラインとして、７１０ｃｍ−１と６８５ｃｍ−１間の最大吸光度とした。 The infrared absorption spectrum obtained under the above conditions was subjected to a peak treatment as follows, and the respective absorbances were obtained.
The absorbance D698 at 698 cm −1 obtained from the infrared absorption spectrum was an absorbance corresponding to the absorption spectrum derived from out-of-plane bending vibration of the benzene ring contained in the polystyrene resin. In the measurement of the absorbance, peak separation was not performed even when another absorption spectrum was overlapped at 698 cm −1 . Absorbance D698 is a straight line connecting the 2000 cm -1 and 870 cm -1 as a baseline, and the maximum absorbance between 710 cm -1 and 685cm -1.

また、赤外吸収スペクトルから得られる２８５０ｃｍ−１での吸光度Ｄ２８５０は、ポリエチレン系樹脂とエチレン系共重合体とに含まれる−Ｃ−ＣＨ２炭化水素のＣＨ２の対称変角振動に由来する吸収スペクトルに対応する吸光度とした。この吸光度の測定では、２８５０ｃｍ−１で他の吸収スペクトルが重なっている場合でもピーク分離を実施しなかった。吸光度Ｄ２８５０は、３１２５ｃｍ−１と２７２０ｃｍ−１を結ぶ直線をベースラインとして、２８７５ｃｍ−１と２８００ｃｍ−１間の最大吸光度とした。
吸光度比からポリスチレン系樹脂とポリエチレン系樹脂及びエチレン系共重合体との組成割合を求める方法としては、ポリスチレン系樹脂とポリエチレン系樹脂及びエチレン系共重合体とを所定の組成割合に均一に混合してなる複数種類の標準試料を作製し、各標準試料についてＡＴＲ法赤外分光分析により粒子表面分析を行なって赤外線吸収スペクトルを得た。得られた赤外吸収スペクトルのそれぞれから吸光度比を算出した。そして、縦軸に組成割合（標準試料中のポリスチレン系樹脂比率（質量％））を、横軸に吸光度比（Ｄ６９８／Ｄ２８５０）をとることで、検量線を描いた。この検量線に基づいて、本発明の複合樹脂粒子の吸光度比から、本発明の複合樹脂粒子におけるポリスチレン系樹脂とポリエチレン系樹脂及びエチレン系共重合体との組成割合を求めた。 Further, the absorbance D2850 at 2850 cm −1 obtained from the infrared absorption spectrum indicates the absorption derived from the symmetric bending vibration of CH 2 of —C—CH 2 hydrocarbon contained in the polyethylene resin and the ethylene copolymer. The absorbance corresponding to the spectrum was used. In the measurement of the absorbance, peak separation was not performed even when another absorption spectrum overlapped at 2850 cm −1 . Absorbance D2850 is a straight line connecting the 3125Cm -1 and 2720cm -1 as a baseline, and the maximum absorbance between 2875cm -1 and 2800 cm -1.
As a method of obtaining the composition ratio of the polystyrene resin, the polyethylene resin, and the ethylene copolymer from the absorbance ratio, the polystyrene resin, the polyethylene resin, and the ethylene copolymer are uniformly mixed to a predetermined composition ratio. A plurality of types of standard samples were prepared, and each standard sample was subjected to particle surface analysis by ATR infrared spectroscopy to obtain an infrared absorption spectrum. The absorbance ratio was calculated from each of the obtained infrared absorption spectra. A calibration curve was drawn by plotting the composition ratio (polystyrene resin ratio in the standard sample (% by mass)) on the vertical axis and the absorbance ratio (D698 / D2850) on the horizontal axis. Based on this calibration curve, the composition ratio of the polystyrene resin, the polyethylene resin, and the ethylene copolymer in the composite resin particles of the present invention was determined from the absorbance ratio of the composite resin particles of the present invention.

なお、前記検量線は、下記の式で近似した。
・Ｄ６９８／Ｄ２８５０≦１．４２の場合
Ｙ＝２１．１１２Ｘ２
・１．４２＜（Ｄ６９８／Ｄ２８５０）＜８．２４の場合
Ｙ＝２８．４１５Ｌｎ（Ｘ２）＋２０．０７２
式中、Ｘ２＝（Ｄ６９８／Ｄ２８５０）、Ｙ＝ポリスチレン系樹脂量（％） The calibration curve was approximated by the following equation.
When D698 / D2850 ≦ 1.42 Y = 21.112X 2
· 1.42 <(D698 / D2850) < For 8.24 Y = 28.415Ln (X 2) +20.072
In the formula, X 2 = (D698 / D2850), Y = amount of polystyrene resin (%)

（発泡成形体の吸光度比（Ｄ６９８／Ｄ２８５０））
発泡成形体の吸光度比は、発泡成形体に以下の処理を施した後、複合樹脂粒子と同様に、測定した。
発泡成形体を１２０℃のオーブンに６〜１２時間投入することで、発泡成形体の密度を５００ｋｇ／ｍ３以上まで収縮処理を行うことで、ポリマー同士が点接着したポーラス形状の成形体を作製した。この得られた成形体から複合樹脂粒子を剥離採取することで吸光度比測定用のサンプルを得た。 (Absorbance ratio of foamed molded article (D698 / D2850))
The absorbance ratio of the foamed article was measured in the same manner as the composite resin particles after the foamed article was subjected to the following treatment.
By pouring the foamed molded article into an oven at 120 ° C. for 6 to 12 hours, the density of the foamed molded article is reduced to 500 kg / m 3 or more, thereby producing a porous molded article in which polymers are point-adhered to each other. did. The composite resin particles were peeled and collected from the obtained molded body to obtain a sample for measuring the absorbance ratio.

（発泡粒子の嵩密度）
発泡粒子の嵩密度は、下記の要領で測定した。まず、発泡粒子をメスシリンダーに５００ｃｍ３の目盛りまで充填した。但し、メスシリンダーを水平方向から目視し、発泡粒子が一粒でも５００ｃｍ３の目盛りに達していれば、充填を終了した。次に、メスシリンダー内に充填した発泡粒子の質量を小数点以下２位の有効数字で秤量し、その質量をＷ（ｇ）とした。次式により発泡粒子の嵩密度を算出した。
嵩密度（ｋｇ／ｍ３）＝Ｗ／５００×１０００ (Bulk density of expanded particles)
The bulk density of the expanded particles was measured in the following manner. First, the graduated cylinder was filled with the expanded particles to a scale of 500 cm 3 . However, the graduated cylinder was visually observed from the horizontal direction, and if even one foamed particle reached the scale of 500 cm 3 , the filling was completed. Next, the mass of the foamed particles filled in the measuring cylinder was weighed to two significant figures after the decimal point, and the mass was defined as W (g). The bulk density of the expanded particles was calculated by the following equation.
Bulk density (kg / m 3 ) = W / 500 × 1000

（発泡成形体の密度）
発泡成形体（成形後、５０℃で４時間以上乾燥させたもの）から切り出した試験片（例７５ｍｍ×３００ｍｍ×３５ｍｍ）の質量（ａ）と体積（ｂ）をそれぞれ有効数字３桁以上になるように測定し、式（ａ）／（ｂ）により発泡成形体の密度（ｋｇ／ｍ３）を求めた。 (Density of foamed molding)
The mass (a) and the volume (b) of a test piece (eg, 75 mm × 300 mm × 35 mm) cut out from a foamed molded product (formed and dried at 50 ° C. for 4 hours or more) each have three or more significant figures. The density (kg / m 3 ) of the foamed molded article was determined by the formulas (a) / (b).

（落球衝撃値）
発泡成形体を、２１５ｍｍ×４０ｍｍ×２０ｍｍの大きさにカットしたサンプルを作製し、このサンプルを、１５５ｍｍのスパンで配置された一対の保持部材上に載置したのち、両保持部材の中間位置でかつサンプルの幅方向の中心位置に、所定の高さから重さ３２１ｇの鋼球を落下させて、サンプルの破壊の有無を確認した。
この試験は、鋼球を落下させる高さを変えて繰り返し行い、サンプルが破壊された高さの最低値を落球衝撃値とし、衝撃強度を評価した。従って、落球衝撃値が高いほど衝撃強度は高くなった。 (Falling ball impact value)
A sample obtained by cutting the foamed molded body into a size of 215 mm × 40 mm × 20 mm was prepared, and this sample was placed on a pair of holding members arranged at a span of 155 mm. At the center of the sample in the width direction, a steel ball having a weight of 321 g was dropped from a predetermined height to check whether the sample was broken.
This test was repeated while changing the height at which the steel balls were dropped, and the minimum value of the height at which the sample was broken was taken as the falling ball impact value, and the impact strength was evaluated. Therefore, the higher the falling ball impact value, the higher the impact strength.

（発泡成形体の２５％圧縮強度）
圧縮強度は、ＪＩＳ Ｋ７２２０：２００６「硬質発泡プラスチック−圧縮特性の求め方」記載の方法により測定した。すなわち、テンシロン万能試験機ＵＣＴ−１０Ｔ（オリエンテック社製）を用いて、５０ｍｍ×５０ｍｍ×２５ｍｍのサイズの試験体について、圧縮速度１０ｍｍ／分として２５％圧縮時（１０ｍｍ変位時）の圧縮強度を測定した。 (25% compressive strength of foam molding)
The compressive strength was measured by the method described in JIS K7220: 2006 “Hard foamed plastics—How to determine compression characteristics”. That is, using a Tensilon universal testing machine UCT-10T (manufactured by Orientec), the compression strength at the time of 25% compression (at the time of 10 mm displacement) at a compression speed of 10 mm / min for a test specimen having a size of 50 mm × 50 mm × 25 mm. It was measured.

（耐熱収縮率）
発泡成形体の耐熱収縮率をＪＩＳ Ｋ６７６７：１９９９「発泡プラスチック−ポリエチレン−試験方法」記載のＢ法にて測定した。具体的には、発泡成形体から縦１５０ｍｍ×横１５０ｍｍ×高さ２０ｍｍの試験片を切り出した。前記試験片の表面に、縦方向に指向する長さ５０ｍｍの直線を３本、互いに平行に５０ｍｍ間隔毎に記入すると共に、横方向に指向する長さ５０ｍｍの直線を３本、互いに平行に５０ｍｍ間隔毎に記入した。しかる後、試験片を８０℃の熱風循環式乾燥機の中に１６８時間に亘って放置した後に取出し、標準状態（２０±２℃、湿度６５±５％）の場所にて１時間に亘って放置した。次に、試験片の表面に記入した６本の直線の長さをそれぞれ測定し、６本の直線の長さの相加平均値Ｌ１を算出した。下記の式に基づいて変化度Ｓを算出し、変化度Ｓの絶対値を耐熱収縮率（％）とした。
Ｓ＝１００×（Ｌ１−５０）／５０
耐熱収縮率について、
○（良） ：０≦Ｓ＜１．５；寸法変化率が低く、寸法の安定性が良好であった
×（不可）：Ｓ≧１．５；寸法の変化が著しく見られた (Heat shrinkage)
The heat-shrinkage rate of the foamed molded article was measured by the method B described in JIS K6767: 1999 “Expanded plastic-polyethylene-test method”. Specifically, a test piece having a length of 150 mm, a width of 150 mm and a height of 20 mm was cut out from the foamed molded article. On the surface of the test piece, three straight lines each having a length of 50 mm and extending in the vertical direction were written at intervals of 50 mm in parallel with each other, and three straight lines each having a length of 50 mm and extending in the horizontal direction and 50 mm each being parallel to each other. Completed at intervals. Thereafter, the test piece was left in a hot air circulating drier at 80 ° C. for 168 hours, then taken out, and taken out under a standard condition (20 ± 2 ° C., humidity 65 ± 5%) for 1 hour. I left it. Next, the lengths of the six straight lines drawn on the surface of the test piece were measured, and the arithmetic average L1 of the lengths of the six straight lines was calculated. The degree of change S was calculated based on the following equation, and the absolute value of the degree of change S was defined as the heat shrinkage (%).
S = 100 × (L1-50) / 50
About the heat shrinkage,
（(Good): 0 ≦ S <1.5; dimensional change rate was low and dimensional stability was good. X (impossible): S ≧ 1.5; dimensional change was remarkably observed.

（燃焼性）
燃焼性は、米国自動車安全基準ＦＭＶＳＳ ３０２に準拠した方法で測定した燃焼速度により評価した。但し、難燃剤を添加した試料のみ燃焼性を評価した。試験片は、３５０ｍｍ×１００ｍｍ×１２ｍｍ（厚み）とし、少なくとも３５０ｍｍ×１００ｍｍの二面には表皮が存在するものとした。
燃焼速度は、以下の基準で評価した。
○：所定の嵩発泡倍数の発泡成形体において、燃焼速度が８０ｍｍ／ｍｉｎ以下の場合もしくは、所定の嵩発泡倍数の発泡成形体において、測定開始点に達する前に消火した場合。この場合の燃焼速度をＡＥ（自己消火性）とした。
×：所定の嵩発泡倍数の発泡成形体において、燃焼速度が８０ｍｍ／ｍｉｎより大きい場合 (Combustion quality)
The flammability was evaluated by the burning rate measured by a method according to the United States automobile safety standard FMVSS302. However, only the sample to which the flame retardant was added was evaluated for flammability. The test piece had a size of 350 mm × 100 mm × 12 mm (thickness), and the skin was present on at least two sides of 350 mm × 100 mm.
The burning rate was evaluated according to the following criteria.
：: When the burning rate is 80 mm / min or less in the foam molded article having the predetermined bulk expansion multiple, or when the fire is extinguished before reaching the measurement start point in the foam molded article having the predetermined bulk expansion multiple. The burning rate in this case was AE (self-extinguishing).
×: When the burning rate is higher than 80 mm / min in a foam molded article having a predetermined bulk expansion multiple.

（成型性）
発泡粒子を発泡成形機の３００ｍｍ×４００ｍｍ×３０ｍｍの金型内に充填し、水蒸気により加熱して予備発泡粒子を発泡させながら、発泡粒子同士を熱融着させた。
水蒸気による加熱の際、水蒸気の蒸気圧力を０．０８ＭＰａから０．２５ＭＰａまで０．０１ＭＰａ刻みで変化させて５０秒間水蒸気を導入し成型テストを実施した。
得られた発泡成形体の、融着率を前記評価基準によって評価し、融着率が９０％以上えられた最も低い蒸気圧力を基に、以下の基準で評価した。
〇：０．１０ＭＰａ以下の蒸気圧で融着率９０％以上の発泡成形体が得られた。低い蒸気調圧での融着良好な発泡成形体が得られ、高い生産性を有していた。
×：０．１０ＭＰａを超える蒸気圧が融着率９０％以上の発泡成形体を得るためには必要であり、生産性に難が見られた。 (Moldability)
The foamed particles were filled in a 300 mm × 400 mm × 30 mm mold of a foaming molding machine, and the foamed particles were heat-sealed while being heated by steam to foam the prefoamed particles.
At the time of heating with steam, the molding pressure was changed from 0.08 MPa to 0.25 MPa in increments of 0.01 MPa, and steam was introduced for 50 seconds to perform a molding test.
The fusion rate of the obtained foamed molded article was evaluated according to the above-described evaluation criteria. Based on the lowest steam pressure at which the fusion rate was 90% or more, the evaluation was performed according to the following criteria.
〇: A foam molded article having a fusion rate of 90% or more was obtained at a vapor pressure of 0.10 MPa or less. A foam molded article having good fusion at a low steam pressure was obtained, and had high productivity.
×: A vapor pressure exceeding 0.10 MPa was necessary to obtain a foam molded article having a fusion rate of 90% or more, and difficulty was observed in productivity.

実施例１
高密度ポリエチレン系樹脂〔Ａ樹脂：東ソー社製、品番１０Ｓ６５Ｂ、密度９４０ｋｇ／ｍ３、ＭＦＲ２．０ｇ／１０分、融点１２６℃、１６０℃における溶融張力７０ｍＮ〕とエチレン酢酸ビニル共重合体〔Ｂ樹脂：日本ポリエチレン製、品番ＬＶ−１１５、ＭＦＲ０．３ｇ／１０分、融点１０８℃、軟化温度８０℃、酢酸ビニル含有量４質量％〕とを２０：８０の質量比になるようにタンブラーミキサーに投入し、１０分間混合した。
次いで、この樹脂混合物を押出機に供給して温度２３０〜２５０℃で溶融混練し、水中カット方式により造粒して楕円球状（卵状）に切断し、改質高密度ポリエチレン系樹脂よりなる種粒子を得た。なお、この種粒子の平均質量は０．６ｍｇであった。
次に、撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子４００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイド（１０時間半減期温度Ｔ１０は１１６．４℃）を０．４ｇ溶解させたスチレン２００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエート（１０時間半減期温度Ｔ１０は１０４．３℃）を５ｇ溶解させたスチレン１４００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比２０／８０）。
次いで、３０℃以下まで冷却し、オートクレーブから複合樹脂粒子を取り出した。複合樹脂粒子２ｋｇと水２リットル、ドデシルベンゼンスルホン酸ナトリウム２．０ｇとを、５リットルの撹拌機付オートクレーブに入れた。更に、発泡剤としてブタン（ｎ−ブタン：ｉ−ブタン＝７：３）１５質量部３００ｇ（５２０ｍＬ）をオートクレーブに入れた。この後、７０℃に昇温し、４時間撹拌を続けることで発泡性粒子を得ることができた。その後、３０℃以下まで冷却して、発泡性粒子をオートクレーブから取り出し、脱水乾燥させた。
次いで、得られた発泡性粒子を嵩密度２９ｋｇ／ｍ３に発泡させることで、発泡粒子を得た。得られた発泡粒子を１日間室温（２３℃）に放置した後、４００ｍｍ×３００ｍｍ×３０ｍｍの大きさの成形用金型に入れた。
その後、０．０６ＭＰａの水蒸気を５０秒間導入して加熱し、次いで、発泡成形体の最高面圧が０．０１ＭＰａに低下するまで冷却することで、密度２９ｋｇ／ｍ３の発泡成形体を得た。
得られた発泡成形体の外観及び融着は共に良好であった。得られた発泡成形体の８０℃×７日間の条件下における寸法変化率、圧縮強度、表面吸光度比、落球衝撃値を測定した。結果を表に示す。 Example 1
High-density polyethylene resin [A resin: Tosoh Corporation, product number 10S65B, density 940 kg / m 3 , MFR 2.0 g / 10 min, melting point 126 ° C, melt tension at 160 ° C 70 mN] and ethylene vinyl acetate copolymer [B resin : Made by Nippon Polyethylene, part number LV-115, MFR 0.3 g / 10 min, melting point 108 ° C, softening temperature 80 ° C, vinyl acetate content 4% by mass] into a tumbler mixer in a mass ratio of 20:80. And mixed for 10 minutes.
Next, this resin mixture is supplied to an extruder, melt-kneaded at a temperature of 230 to 250 ° C., granulated by an underwater cutting method, cut into elliptical spheres (eggs), and seeded from a modified high-density polyethylene resin. Particles were obtained. The average mass of the seed particles was 0.6 mg.
Next, in a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 400 g of seed particles were dispersed in a dispersing medium at 30 ° C., maintained for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 200 g of styrene in which 0.4 g of dicumyl peroxide (10-hour half-life temperature T10 is 116.4 ° C.) was dissolved as a polymerization initiator was dropped into the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and added dropwise over 10 minutes to the suspension cooled to 115 ° C., and then t-butylperoxybenzoate (10-hour half-life temperature T10 was 104 (3.degree. C.) was added dropwise at a rate of 0.50 parts by mass / second (a rate with respect to 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was added dropwise over 30 minutes. After the addition, the dispersion medium was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles were obtained (mass ratio of seed particles to polystyrene of 20/80).
Next, the mixture was cooled to 30 ° C. or lower, and the composite resin particles were taken out of the autoclave. 2 kg of the composite resin particles, 2 liters of water, and 2.0 g of sodium dodecylbenzenesulfonate were placed in a 5-liter autoclave equipped with a stirrer. Further, 300 g (520 mL) of 15 parts by mass of butane (n-butane: i-butane = 7: 3) as a foaming agent was put in the autoclave. Thereafter, the temperature was raised to 70 ° C., and stirring was continued for 4 hours, whereby foamable particles could be obtained. Thereafter, the mixture was cooled to 30 ° C. or lower, and the expandable particles were taken out of the autoclave and dehydrated and dried.
Next, the obtained expandable particles were expanded to a bulk density of 29 kg / m 3 to obtain expanded particles. After leaving the obtained foamed particles at room temperature (23 ° C.) for one day, they were placed in a molding die having a size of 400 mm × 300 mm × 30 mm.
Thereafter, steam of 0.06 MPa was introduced for 50 seconds, heated, and then cooled until the maximum surface pressure of the foamed molded article was reduced to 0.01 MPa, thereby obtaining a foamed molded article having a density of 29 kg / m 3 . .
The appearance and fusion of the obtained foamed molded article were both good. The dimensional change rate, compressive strength, surface absorbance ratio, and falling ball impact value of the obtained foamed molded article under the conditions of 80 ° C. × 7 days were measured. The results are shown in the table.

実施例２
実施例１と同様に平均質量０．６ｍｇの種粒子を得た。
次に、撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子８００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．８ｇ溶解させたスチレン４００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを１．８ｇ溶解させたスチレン８００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比４０／６０）。
その後、反応系の温度を６０℃にして、この懸濁液中に、難燃剤としてトリス（２，３−ジブロモプロピル）イソシアヌレート（日本化成社製：ＴＡＩＣ６Ｂ）５０ｇと、難燃助剤としてジクミルパーオキサイド（ＤＣＰ）１０ｇとを投入した。投入後、反応系の温度を１３０℃に昇温し、２時間撹拌を続けることで難燃剤を含有した複合樹脂粒子を得た。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。
得られた発泡成形体の外観及び融着は共に良好であった。得られた発泡成形体の８０℃×７日間の条件下における寸法変化率、圧縮強度、表面吸光度比、落球衝撃値を測定した。結果を表に示す。また、難燃剤添加の効果を確認するため、燃焼性の測定も行った。 Example 2
Seed particles having an average mass of 0.6 mg were obtained in the same manner as in Example 1.
Next, in a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 800 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 400 g of styrene in which 0.8 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and added dropwise to the suspension at 115 ° C. over 10 minutes, and then 800 g of styrene in which 1.8 g of t-butylperoxybenzoate was dissolved. Was added dropwise at a rate of 0.50 parts by mass / second (a rate based on 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide in 100 g of pure water as a bubble regulator was added dropwise over 30 minutes, and after dropping, the mixture was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles could be obtained (mass ratio of seed particles to polystyrene of 40/60).
Thereafter, the temperature of the reaction system was raised to 60 ° C., and 50 g of tris (2,3-dibromopropyl) isocyanurate (TAIC6B, manufactured by Nippon Kasei Co., Ltd.) was added as a flame retardant, and diic was used as a flame retardant. 10 g of mill peroxide (DCP) was charged. After the introduction, the temperature of the reaction system was raised to 130 ° C., and stirring was continued for 2 hours to obtain composite resin particles containing a flame retardant.
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.
The appearance and fusion of the obtained foamed molded article were both good. The dimensional change rate, compressive strength, surface absorbance ratio, and falling ball impact value of the obtained foamed molded article under the conditions of 80 ° C. × 7 days were measured. The results are shown in the table. In addition, in order to confirm the effect of the addition of the flame retardant, the flammability was measured.

実施例３
高密度ポリエチレン系樹脂とエチレン酢酸ビニル共重合体とを４０：６０の質量比になるようにすること以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子６００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．６ｇ溶解させたスチレン３００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを２．１ｇ溶解させたスチレン１１００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比３０／７０）。
その後、反応系の温度を６０℃にして、この懸濁液中に、難燃剤としてトリス（２，３−ジブロモプロピル）イソシアヌレート（日本化成社製：ＴＡＩＣ６Ｂ）５０ｇと、難燃助剤としてビスクミル１０ｇとを投入した。投入後、反応系の温度を１３０℃に昇温し、２時間撹拌を続けることで難燃剤を含有した複合樹脂粒子を得た。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。
得られた発泡成形体の外観及び融着は共に良好であった。得られた発泡成形体の８０℃×７日間の条件下における寸法変化率、圧縮強度、表面吸光度比、落球衝撃値を測定した。結果を表に示す。また、難燃剤添加の効果を確認するため、燃焼性の測定も行った。 Example 3
Seed particles were obtained in the same manner as in Example 1 except that the mass ratio of the high-density polyethylene resin and the ethylene-vinyl acetate copolymer was set to be 40:60.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 600 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 300 g of styrene in which 0.6 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and dropped over 10 minutes in the suspension cooled to 115 ° C., and then 1100 g of styrene in which 2.1 g of t-butylperoxybenzoate was dissolved Was added dropwise at a rate of 0.50 parts by mass / second (a rate based on 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was added dropwise over 30 minutes. After the addition, the dispersion medium was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles were obtained (mass ratio of seed particles to polystyrene of 30/70).
Thereafter, the temperature of the reaction system was raised to 60 ° C., and 50 g of tris (2,3-dibromopropyl) isocyanurate (TAIC6B, manufactured by Nippon Kasei) and biscumyl as a flame retardant were added to the suspension. 10 g were charged. After the introduction, the temperature of the reaction system was raised to 130 ° C., and stirring was continued for 2 hours to obtain composite resin particles containing a flame retardant.
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.
The appearance and fusion of the obtained foamed molded article were both good. The dimensional change rate, compressive strength, surface absorbance ratio, and falling ball impact value of the obtained foamed molded article under the conditions of 80 ° C. × 7 days were measured. The results are shown in the table. In addition, in order to confirm the effect of the addition of the flame retardant, flammability was measured.

実施例４
エチレン酢酸ビニル共重合体として〔日本ポリエチレン製、品番ＬＶ−４３０、ＭＦＲ１．０ｇ／１０分、融点８９℃、軟化温度７３℃、酢酸ビニル由来成分含有量１５重量％〕を使用し、高密度ポリエチレン系樹脂とエチレン酢酸ビニル共重合体とを３０：７０の質量比になるようにすること以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子３００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．３ｇ溶解させたスチレン１５０ｇを３０分かけて滴下した。滴下後、１１５℃に５５分（１℃／分）かけて昇温し、１１５℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３０℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを２．８ｇ溶解させたスチレン１５５０ｇを０．４０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比１５／８５）。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。 Example 4
High-density polyethylene was used as an ethylene-vinyl acetate copolymer [manufactured by Nippon Polyethylene, product number LV-430, MFR 1.0 g / 10 min, melting point 89 ° C., softening temperature 73 ° C., vinyl acetate-derived component content 15% by weight]. Seed particles were obtained in the same manner as in Example 1 except that the mass ratio of the system resin and the ethylene-vinyl acetate copolymer was adjusted to 30:70.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 300 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 150 g of styrene in which 0.3 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropwise addition, the temperature was raised to 115 ° C. over 55 minutes (1 ° C./min), and the temperature was maintained at 115 ° C. for 60 minutes, thereby impregnating the seed particles with styrene. After the impregnation, the temperature was raised to 130 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and dropped over 10 minutes in the suspension cooled to 115 ° C., and then 1550 g of styrene in which 2.8 g of t-butylperoxybenzoate was dissolved. Was dropped at a rate of 0.40 parts by mass / second (a rate based on 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide in 100 g of pure water as a bubble regulator was added dropwise over 30 minutes, and after dropping, the mixture was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles could be obtained (mass ratio of seed particles to polystyrene of 15/85).
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.

実施例５
高密度ポリエチレン系樹脂として〔日本ポリエチレン社製、品番ＨＹ３５０、密度９５１ｋｇ／ｍ３、ＭＦＲ２．５ｇ／１０分、融点１３２℃〕を使用し、高密度ポリエチレン系樹脂とエチレン酢酸ビニル共重合体とを１０：９０の質量比になるようにすること以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子６００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．６ｇ溶解させたスチレン３００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを２．１ｇ溶解させたスチレン１１００ｇを０．３０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比３０／７０）。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。 Example 5
Using a high-density polyethylene resin [manufactured by Nippon Polyethylene Co., Ltd., product number HY350, density 951 kg / m 3 , MFR 2.5 g / 10 minutes, melting point 132 ° C.], a high-density polyethylene resin and an ethylene-vinyl acetate copolymer were used. Seed particles were obtained in the same manner as in Example 1 except that the mass ratio was 10:90.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 600 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 300 g of styrene in which 0.6 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and dropped over 10 minutes in the suspension cooled to 115 ° C., and then 1100 g of styrene in which 2.1 g of t-butylperoxybenzoate was dissolved Was added dropwise at a rate of 0.30 parts by mass / second (a rate relative to 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was added dropwise over 30 minutes. After the addition, the dispersion medium was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles were obtained (mass ratio of seed particles to polystyrene of 30/70).
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.

比較例１
高密度ポリエチレン系樹脂とエチレン酢酸ビニル共重合体とを７０：３０の質量比になるようにすること以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子６００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．６ｇ溶解させたスチレン３００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを２．１ｇ溶解させたスチレン１１００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比３０／７０）。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。 Comparative Example 1
Seed particles were obtained in the same manner as in Example 1 except that the mass ratio of the high-density polyethylene resin to the ethylene-vinyl acetate copolymer was 70:30.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 600 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 300 g of styrene in which 0.6 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and dropped over 10 minutes in the suspension cooled to 115 ° C., and then 1100 g of styrene in which 2.1 g of t-butylperoxybenzoate was dissolved Was added dropwise at a rate of 0.50 parts by mass / second (a rate based on 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was added dropwise over 30 minutes. After the addition, the dispersion medium was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles were obtained (mass ratio of seed particles to polystyrene of 30/70).
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.

比較例２
エチレン酢酸ビニル共重合体を使用しないこと以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子８００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．８ｇ溶解させたスチレン４００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを１．８ｇ溶解させたスチレン８００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比４０／６０）。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。 Comparative Example 2
Seed particles were obtained in the same manner as in Example 1 except that the ethylene-vinyl acetate copolymer was not used.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 800 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 400 g of styrene in which 0.8 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and dropped over 10 minutes in the suspension cooled to 115 ° C., and then 800 g of styrene in which 1.8 g of t-butylperoxybenzoate was dissolved. Was added dropwise at a rate of 0.50 parts by mass / second (a rate based on 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was added dropwise over 30 minutes. After the addition, the dispersion medium was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles could be obtained (mass ratio of seed particles to polystyrene of 40/60).
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.

比較例３
高密度ポリエチレン系樹脂〔東ソー社製、品番０９Ｓ５３Ｂ、密度９３６ｋｇ／ｍ３、ＭＦＲ２．６ｇ／１０分、融点１２３℃〕を使用し、エチレン酢酸ビニル共重合体を使用しないこと以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子６００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．６ｇ溶解させたスチレン３００ｇを３０分かけて滴下した。滴下後、３０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１４０℃に昇温し、この温度で２時間重合（第１重合）させた。
次に、１２０℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ジクミルパーオキサイドを２．５ｇ溶解させたスチレン１１００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。滴下後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下した。次いで、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比３０／７０）。
その後、反応系の温度を６０℃にして、この懸濁液中に、難燃剤としてトリス（２，３−ジブロモプロピル）イソシアヌレート（日本化成社製：ＴＡＩＣ６Ｂ）５０ｇと、難燃助剤としてジクミルパーオキサイド（ＤＣＰ）１０ｇとを投入した。投入後、反応系の温度を１３０℃に昇温し、２時間撹拌を続けることで難燃剤を含有した複合樹脂粒子を得た。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。 Comparative Example 3
Example 1 was repeated except that a high-density polyethylene resin (manufactured by Tosoh Corporation, product number 09S53B, density 936 kg / m 3 , MFR 2.6 g / 10 min, melting point 123 ° C.) was not used, and no ethylene-vinyl acetate copolymer was used. Similarly, seed particles were obtained.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 600 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 300 g of styrene in which 0.6 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the seed particles were held for 30 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 140 ° C., and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and added dropwise over 10 minutes to the suspension cooled to 120 ° C., and 1100 g of styrene in which 2.5 g of dicumyl peroxide was dissolved was added to 0%. It was dropped at a rate of .50 parts by mass / second (a rate with respect to 100 parts by weight of the seed particles). After the dropping, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was dropped over 30 minutes. Next, the temperature was raised to 140 ° C., and this temperature was maintained for 3 hours to carry out polymerization (second polymerization). As a result of this polymerization, composite resin particles were obtained (mass ratio of seed particles to polystyrene of 30/70).
Thereafter, the temperature of the reaction system was raised to 60 ° C., and 50 g of tris (2,3-dibromopropyl) isocyanurate (TAIC6B, manufactured by Nippon Kasei Co., Ltd.) was added as a flame retardant to the suspension. 10 g of mill peroxide (DCP) was charged. After the introduction, the temperature of the reaction system was raised to 130 ° C., and stirring was continued for 2 hours to obtain composite resin particles containing a flame retardant.
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.

比較例４
高密度ポリエチレン系樹脂の代わりに直鎖状低密度ポリエチレン〔日本ポリエチレン社製、品番ＮＦ４４４Ａ、密度９１２ｋｇ／ｍ３、ＭＦＲ２ｇ／１０分、融点１２１℃〕を使用すること以外は実施例１と同様にして種粒子を得た。
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で種粒子８００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．８ｇ溶解させたスチレン４００ｇを３０分かけて滴下した。滴下後、１２０℃に６０分（１℃／分）かけて昇温し、１２０℃で６０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に１５分（１℃／分）かけて昇温し、この温度で２時間重合（第１重合）させた。
次に、１１５℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを１．８ｇ溶解させたスチレン８００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。その後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下し、滴下後、１１５℃で１時間保持することで、種粒子中にスチレン及び気泡調整剤を含浸させた。含浸後、１４０℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比４０／６０）。
その後、反応系の温度を６０℃にして、この懸濁液中に、難燃剤としてトリス（２，３−ジブロモプロピル）イソシアヌレート（日本化成社製：ＴＡＩＣ６Ｂ）５０ｇと、難燃助剤としてジクミルパーオキサイド（ＤＣＰ）１０ｇとを投入した。投入後、反応系の温度を１３０℃に昇温し、２時間撹拌を続けることで難燃剤を含有した複合樹脂粒子を得た。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。 Comparative Example 4
In the same manner as in Example 1 except that a linear low-density polyethylene [manufactured by Nippon Polyethylene Co., Ltd., product number NF444A, density 912 kg / m 3 , MFR 2 g / 10 min, melting point 121 ° C.] is used instead of the high-density polyethylene resin. To obtain seed particles.
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 800 g of seed particles were dispersed in a dispersing medium at 30 ° C., kept for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 400 g of styrene in which 0.8 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the temperature was raised to 120 ° C. over 60 minutes (1 ° C./min), and the temperature was maintained at 120 ° C. for 60 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C. over 15 minutes (1 ° C./min), and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and dropped over 10 minutes in the suspension cooled to 115 ° C., and then 800 g of styrene in which 1.8 g of t-butylperoxybenzoate was dissolved. Was added dropwise at a rate of 0.50 parts by mass / second (a rate based on 100 parts by mass of the seed particles). Thereafter, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was added dropwise over 30 minutes. After the addition, the dispersion medium was maintained at 115 ° C. for 1 hour, so that styrene was contained in the seed particles. And a cell conditioner. After the impregnation, the temperature was raised to 140 ° C. and maintained at this temperature for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles could be obtained (mass ratio of seed particles to polystyrene of 40/60).
Thereafter, the temperature of the reaction system was raised to 60 ° C., and 50 g of tris (2,3-dibromopropyl) isocyanurate (TAIC6B, manufactured by Nippon Kasei Co., Ltd.) was added as a flame retardant to the suspension. 10 g of mill peroxide (DCP) was charged. After the introduction, the temperature of the reaction system was raised to 130 ° C., and stirring was continued for 2 hours to obtain composite resin particles containing a flame retardant.
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.

比較例５
撹拌機付の５リットルのオートクレーブに、ピロリン酸マグネシウム４０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．６ｇを純水２ｋｇに分散させて分散用媒体を得た。分散用媒体に３０℃で実施例１と同様の種粒子４００ｇを分散させて１０分間保持し、次いで６０℃に昇温して懸濁液を得た。更に、この懸濁液に、重合開始剤としてジクミルパーオキサイドを０．４ｇ溶解させたスチレン２００ｇを３０分かけて滴下した。滴下後、３０分間保持することで、種粒子中にスチレンを含浸させた。含浸後、１３５℃に昇温し、この温度で２時間重合（第１重合）させた。
次に、１２０℃に下げた懸濁液中に、ドデシルベンゼンスルホン酸ナトリウム３ｇを純水２０ｇに分散させ１０分かけて滴下した後、ｔ−ブチルパーオキシベンゾエートを２．１ｇ溶解させたスチレン１４００ｇを０．５０質量部／秒の速度（種粒子１００質量部に対する速度）で滴下した。滴下後、気泡調整剤としてエチレンビスステアリン酸アミド３ｇを純水１００ｇに分散させて作製した分散媒体を３０分かけて滴下した。次いで、１３５℃に昇温し、この温度で３時間保持して重合（第２重合）させた。この重合の結果、複合樹脂粒子を得ることができた（種粒子とポリスチレンとの質量比３０／７０）。
その後、反応系の温度を６０℃にして、この懸濁液中に、難燃剤としてトリス（２，３−ジブロモプロピル）イソシアヌレート（日本化成社製：ＴＡＩＣ６Ｂ）５０ｇと、難燃助剤としてジクミルパーオキサイド（ＤＣＰ）１０ｇとを投入した。投入後、反応系の温度を１３０℃に昇温し、２時間撹拌を続けることで難燃剤を含有した複合樹脂粒子を得た。
次いで、実施例１と同様にして、発泡性粒子、発泡粒子（嵩密度２９ｋｇ／ｍ３）及び発泡成形体（密度２９ｋｇ／ｍ３）を得た。
表１に実施例及び比較例の発泡成形体の製造条件を示す。表２に実施例及び比較例の評価結果を示す。 Comparative Example 5
In a 5-liter autoclave equipped with a stirrer, 40 g of magnesium pyrophosphate and 0.6 g of sodium dodecylbenzenesulfonate were dispersed in 2 kg of pure water to obtain a dispersion medium. 400 g of the same seed particles as in Example 1 were dispersed in a dispersion medium at 30 ° C. and maintained for 10 minutes, and then heated to 60 ° C. to obtain a suspension. Further, 200 g of styrene in which 0.4 g of dicumyl peroxide was dissolved as a polymerization initiator was added dropwise to the suspension over 30 minutes. After the dropping, the seed particles were held for 30 minutes to impregnate the seed particles with styrene. After the impregnation, the temperature was raised to 135 ° C., and polymerization (first polymerization) was performed at this temperature for 2 hours.
Next, 3 g of sodium dodecylbenzenesulfonate was dispersed in 20 g of pure water and added dropwise over 10 minutes to the suspension cooled to 120 ° C., and then 1400 g of styrene in which 2.1 g of t-butylperoxybenzoate was dissolved. Was added dropwise at a rate of 0.50 parts by mass / second (a rate based on 100 parts by mass of the seed particles). After the dropping, a dispersion medium prepared by dispersing 3 g of ethylenebisstearic acid amide as a bubble regulator in 100 g of pure water was dropped over 30 minutes. Next, the temperature was raised to 135 ° C., and the temperature was maintained for 3 hours to perform polymerization (second polymerization). As a result of this polymerization, composite resin particles were obtained (mass ratio of seed particles to polystyrene of 30/70).
Thereafter, the temperature of the reaction system was raised to 60 ° C., and 50 g of tris (2,3-dibromopropyl) isocyanurate (TAIC6B, manufactured by Nippon Kasei Co., Ltd.) was added as a flame retardant to the suspension. 10 g of mill peroxide (DCP) was charged. After the introduction, the temperature of the reaction system was raised to 130 ° C., and stirring was continued for 2 hours to obtain composite resin particles containing a flame retardant.
Subsequently, in the same manner as in Example 1, expandable particles, expanded particles (bulk density: 29 kg / m 3 ), and expanded molded articles (density: 29 kg / m 3 ) were obtained.
Table 1 shows the production conditions for the foamed molded articles of the examples and comparative examples. Table 2 shows the evaluation results of the examples and the comparative examples.

Figure 2020050784
Figure 2020050784

Figure 2020050784
Figure 2020050784

表２より、実施例では、発泡成形体の機械強度及び耐熱性、発泡成形体を製造する際の成形加工性を改善できていることが分かる。   From Table 2, it can be seen that in the examples, the mechanical strength and heat resistance of the foamed molded article and the moldability at the time of producing the foamed molded article could be improved.

Claims (9)

高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂とを含む発泡用の複合樹脂粒子であって、
高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体とポリスチレン系樹脂とが、以下の質量比：
（ｉ）前記高密度ポリエチレン系樹脂とカルボニル基を有するエチレン系共重合体の合計量／ポリスチレン系樹脂＝５／９５〜４０／６０、
（ｉｉ）前記高密度ポリエチレン系樹脂／カルボニル基を有するエチレン系共重合体＝５／９５〜５０／５０
で含まれ、
前記複合樹脂粒子は、
・その表面をＡＴＲ法により赤外分光分析することで得られる赤外線吸収スペクトルから算出された２８５０ｃｍ−１の吸光度（Ｄ２８５０）と６９８ｃｍ−１の吸光度（Ｄ６９８）との比である表面吸光度比Ｄ１（Ｄ６９８／Ｄ２８５０）と、
・前記複合樹脂粒子に由来する発泡粒子の融着体から構成される発泡成形体の表面をＡＴＲ法により赤外分光分析することで得られる赤外線吸収スペクトルから算出された２８５０ｃｍ−１の吸光度（Ｄ２８５０）及び６９８ｃｍ−１の吸光度（Ｄ６９８）との比である表面吸光度比Ｄ２（Ｄ６９８／Ｄ２８５０）とが、下記値：
Ｄ１＝０．５〜２．５、
Ｄ２／Ｄ１＝０．１〜０．９５
を示す構造を有し、
前記高密度ポリエチレン系樹脂が、９３５〜９６０ｋｇ／ｍ３の密度を有することを特徴とする複合樹脂粒子。 Composite resin particles for foaming comprising a high-density polyethylene resin and an ethylene copolymer having a carbonyl group and a polystyrene resin,
The mass ratio of the high-density polyethylene resin, the ethylene copolymer having a carbonyl group, and the polystyrene resin is as follows:
(I) the total amount of the high-density polyethylene-based resin and the ethylene-based copolymer having a carbonyl group / polystyrene-based resin = 5/95 to 40/60;
(Ii) The high-density polyethylene-based resin / ethylene-based copolymer having a carbonyl group = 5/95 to 50/50
Included in
The composite resin particles,
Part surface ATR method by infrared spectroscopy absorbance of 2850 cm -1, which is calculated from the infrared absorption spectrum obtained by (D2850) to the absorbance of 698cm -1 (D698) and the surface absorbance ratio is the ratio of D1 ( D698 / D2850),
An absorbance of 2850 cm −1 (D2850) calculated from an infrared absorption spectrum obtained by performing infrared spectroscopy analysis on the surface of a foamed molded product composed of a fusion body of foamed particles derived from the composite resin particles by the ATR method; ) And the absorbance at 698 cm -1 (D698), the surface absorbance ratio D2 (D698 / D2850), are the following values:
D1 = 0.5-2.5,
D2 / D1 = 0.1 to 0.95
Having a structure showing
The composite resin particles, wherein the high-density polyethylene resin has a density of 935 to 960 kg / m 3 . 前記カルボニル基を有するエチレン系共重合体がエチレン酢酸ビニル共重合体であり、前記エチレン酢酸ビニル共重合体が酢酸ビニル由来成分を１〜２０質量％含む請求項１に記載の複合樹脂粒子。   The composite resin particles according to claim 1, wherein the ethylene-based copolymer having a carbonyl group is an ethylene-vinyl acetate copolymer, and the ethylene-vinyl acetate copolymer contains 1 to 20% by mass of a component derived from vinyl acetate. 前記高密度ポリエチレンが、４０ｍＮ以上の１６０℃における溶融張力を有する請求項１又は２に記載の複合樹脂粒子   The composite resin particle according to claim 1, wherein the high-density polyethylene has a melt tension at 160 ° C. of 40 mN or more. 前記複合樹脂粒子が、高密度ポリエチレンとエチレン酢酸ビニル共重合体とを含む種粒子と、前記種粒子に含浸重合したスチレン系モノマー由来のポリスチレン系樹脂とを含む請求項１〜３のいずれか１つに記載の複合樹脂粒子。   The composite resin particle according to any one of claims 1 to 3, wherein the composite resin particle includes a seed particle containing a high-density polyethylene and an ethylene-vinyl acetate copolymer, and a polystyrene resin derived from a styrene monomer impregnated and polymerized in the seed particle. 5. The composite resin particles according to any one of the above. 前記高密度ポリエチレンの融点（Ｔ１）と前記エチレン酢酸ビニル共重合体の融点（Ｔ２）の差が１０〜４０℃であり、かつ前記種粒子の軟化温度（Ｔ３）が１１０〜１２５℃である請求項４に記載の複合樹脂粒子。   The difference between the melting point (T1) of the high-density polyethylene and the melting point (T2) of the ethylene-vinyl acetate copolymer is 10 to 40C, and the softening temperature (T3) of the seed particles is 110 to 125C. Item 6. The composite resin particle according to Item 4, 請求項１〜５のいずれか１つに記載の複合樹脂粒子と、発泡剤とを含む発泡性粒子。   An expandable particle comprising the composite resin particle according to any one of claims 1 to 5 and a blowing agent. 請求項６に記載の発泡性粒子を発泡させて得られた発泡粒子。   Expanded particles obtained by expanding the expandable particles according to claim 6. 請求項７に記載の発泡粒子を発泡成形させて得られた発泡成形体。   A foam molded article obtained by subjecting the foamed particles according to claim 7 to foam molding. 前記発泡成形体が、自動車部材用、部品梱包材用又は緩衝材用である請求項８に記載の発泡成形体。   The foamed molded article according to claim 8, wherein the foamed molded article is used for an automobile member, a component packaging material, or a cushioning material.
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