JP4789307B2

JP4789307B2 - Functional polyolefin resin expanded particles and in-mold molded articles thereof

Info

Publication number: JP4789307B2
Application number: JP2000188946A
Authority: JP
Inventors: 康上田; 英毅渡辺
Original assignee: Asahi Kasei Chemicals Corp
Current assignee: Asahi Kasei Chemicals Corp
Priority date: 2000-06-23
Filing date: 2000-06-23
Publication date: 2011-10-12
Anticipated expiration: 2020-06-23
Also published as: JP2002003634A

Description

【０００１】
【発明の属する技術分野】
本発明は、導電性や帯電防止性及び難燃性等の各種機能を有する改質剤を、ポリオレフィン系樹脂発泡粒子の表面に定着した機能性ポリオレフィン系樹脂発泡粒子、その型内成形体の改良及びその製造方法に関する。
【０００２】
【従来の技術】
近年、電子、電気関連機器、特にパーソナルコンピューター及びその周辺機器である液晶表示装置や記憶装置は、インターネットに代表される情報文化の発達と共に急激な勢いで成長し続けている分野である。
これらの機器は、ＬＳＩ等の半導体製品が組み込まれていて、静電気破壊を生じやすいために、これらの輸送用緩衝包装材料には、高機能の緩衝性能は勿論のこと、導電性や帯電防止性能等の機能を有すポリオレフィン系樹脂型内発泡成形体の緩衝材料が必要とされ、その重要性がますます高まりつつあるのが現状である。
【０００３】
例えば、導電性能を有するポリオレフィン系樹脂型内発泡成形体としては、ポリオレフィン系樹脂に導電性を付与する改質剤として導電性カーボンブラックを１０〜２０数部の高濃度で押出造粒装置にて練り込んだ樹脂粒子を公知の方法で発泡粒子とし、この発泡粒子を型内成形した導電性型内成形体が提供されているが、無機物である導電性カーボンブラックを多量に含んでいるために引張強度や引裂強度等の機械的強度が低かったり、又、発泡粒子の気泡膜には、無数の微小欠陥を有していて独立気泡率が極端に低いために緩衝特性の重要物性である回復性も悪く、緩衝材として致命的な欠点がある。
【０００４】
この欠点を解消したものとして、ポリオレフィン系樹脂発泡粒子の導電性型内成形体が特公平７−５３３８１号公報に開示されている。
この型内成形体は、高剪断混合機を用いて、加熱調温された発泡粒子の表面に導電性カーボンブラックを定着させるために、先ず接着性樹脂層を形成した後、導電性カーボンブラックをまぶし付け溶融状態の接着性樹脂に絡み合わせた後、更に接着性樹脂を被覆して得た発泡粒子を型内成形したものである。
この成形体の特性は、発泡粒子間の融着性が高く、然も回復性に優れている上に、表面抵抗値が１０⁴Ω〜１０¹³Ωと言う導電性レベルから帯電防止性に至る広い範囲の性能を有するポリオレフィン系樹脂発泡粒子の型内成形体を提案したものである。
【０００５】
【発明が解決しょうとする課題】
しかしながら上記型内成形体に用いる発泡粒子は、改質剤の接着性樹脂への分散は高剪断混合下で行われるために、良好な分散状態の発泡粒子を得ようとすると混合翼の形状が制限されると共に、発泡粒子の表面温度や混合翼の回転数そして混合時間等の高剪断混合条件を極めて狭い範囲で制御しなければならず、高度で且つ熟練度の高い技術を要すると共にこの最良条件範囲から外れると改質剤の均一分散が不充分となって目的とする改質効果が発現しなかったり、外観品位が低下すると言った品質、性能上の安定性に問題がある。
【０００６】
又、改質剤を発泡粒子表面に強固に定着させた型内成形体を得ようとすると、発泡粒子の表面に改質剤を定着させる工程が、１）接着性樹脂層の形成工程、２）改質剤まぶし工程、３）改質剤の定着強化工程の３工程が必須であることから作業が複雑で然も加工サイクルが長く経済性が悪いと言った問題点もある。更に、改質剤が微粉末で、特に嵩高な導電性カーボンブラックは取り扱い時に容易に飛散したりして周囲の機械設備を汚染したり、作業者が呼吸時に体内に吸引し健康を害する危険性がある。
【０００７】
【課題を解決するための手段】
本発明は以下の通りのものである。
１．ポリオレフィン系樹脂発泡粒子の表面に改質剤を含む接着性樹脂を定着させた機能性ポリオレフィン系樹脂発泡粒子の製造方法であって、高速流動混合機を用いて、ポリオレフィン系樹脂発泡粒子の表面に、融点が上記発泡粒子融点の−３０℃〜−３℃の範囲であり、且つメルトフローレートが３〜８０ｇ／１０分の溶融流動性を示すところの改質剤を溶融混練した接着性樹脂の粉砕粉体を上記発泡粒子の重量に対して１〜１５重量％溶融被覆することを特徴とする機能性ポリオレフィン系樹脂発泡粒子の製造方法。
２．上記接着性樹脂の粉砕粉体が、１０〜１４５メッシュ篩い（パス）の粒径であることを特徴とする１．記載の機能性ポリオレフィン系樹脂発泡粒子の製造方法。
３．上記改質剤は、導電性カーボーンブラックあって、その添加濃度が接着性樹脂の重量に対して３〜１５重量％であることを特徴とする１．又は２．記載の機能性ポリオレフィン系樹脂発泡粒子の製造方法。
４．上記改質剤は、ＨＬＢが２〜１０の界面活性剤型帯電防止剤であって、その添加濃度が接着性樹脂の重量に対して０．５〜１０重量％であることを特徴とする１．又は２．記載の機能性ポリオレフィン系樹脂発泡粒子の製造方法。
５．上記改質剤は、ポリオレフィン系樹脂の高分子型永久帯電防止剤であって、その添加濃度が接着性樹脂の重量に対して７〜５０重量％であることを特徴とする１．又は２．記載の機能性ポリオレフィン系樹脂発泡粒子の製造方法。
本発明の機能性ポリオレフィン系樹脂発泡粒子は、ポリオレフィン系樹脂発泡粒子の表面に改質剤を含む接着性樹脂を定着させた機能性ポリオレフィン系樹脂発泡粒子において、好ましくは高速流動混合機を用いて、ポリオレフィン系樹脂発泡粒子の表面に、融点が上記発泡粒子融点の−３０℃〜−３℃の範囲であり、且つメルトフローレートが３〜８０ｇ／１０分の溶融流動性を示すところの改質剤を溶融混練した接着性樹脂の粉砕粉体が上記発泡粒子の重量に対して１〜１５重量％溶融被覆されていることを特徴とする。接着性樹脂の粉砕粉体は、１０〜１４５メッシュ篩い（パス）の粒径であることが好ましい。改質剤は、導電性カーボーンブラックあって、その添加濃度が接着性樹脂の重量に対して３〜１５重量％であることが好ましい。又、改質剤は、ＨＬＢが２〜１０の界面活性剤型帯電防止剤であって、その添加濃度が接着性樹脂の重量に対して０．５〜１０重量％であることが好ましい。更に改質剤は、ポリオレフィン系樹脂の高分子型永久帯電防止剤であって、その添加濃度が接着性樹脂の重量に対して７〜５０重量％であることが好ましい。
【０００８】
そして、本発明の型内成形体は、上記のいずれかの機能性ポリオレフィン系樹脂発泡粒子を型内に充填して加熱、好ましくは発泡粒子の融点の＋２℃〜＋１２℃の範囲の温度の水蒸気加熱し、粒子相互を融着せしめて得られる倍率が５〜５５ｃｍ³／ｇの機能性ポリオレフィン系樹脂発泡型内成形体であることを特徴とするものである。
【０００９】
【発明の実施の形態】
以下、本発明の各構成を項分けし、図、表等を用いて詳細に説明する。
【００１０】
▲１▼「ポリオレフィン系樹脂発泡粒子」
○架橋型及び無架橋型を総称する。
○ポリオレフィン系樹脂としては、低、中、高密度ポリエチレン、直鎖状低密度ポリエチレン、超高密度ポリエチレン、メタロセン触媒のポリエチレン、エチレン−酢酸ビニル共重合体等で代表されるエチレン系樹脂、ポリプロピレン、共重合成分が、エチレン、ブテン−１、４−メチルペンテン−１等の１種以上であるプロピレンとのランダム及びブロック共重合樹脂、又はこれらの２種以上が配合された混合樹脂である。
【００１１】
○発泡粒子の発泡倍率は、３ｃｍ³／ｇ〜１５ｃｍ³／ｇ、好ましくは４ｃｍ³／ｇ〜１０ｃｍ³／ｇである。
・発泡倍率が３ｃｍ³／ｇ未満であると、型内成形（高倍率）に用いるための逐次高発泡化作業が多段階となり発泡成形の生産工程が煩雑で不経済である。
・発泡倍率が１５ｃｍ³／ｇを越えると、発泡粒子１個の重量が軽くなり高速流動混合時の摩擦熱の発生が不十分となり、昇温時間が長くなると共に改質剤の定着が不均一となる。また、発泡粒子の融点近傍に加熱される熱で、収縮し倍率低下が顕著となると共に混合槽への投入重量が少なくなって、加工が不経済となる。
【００１２】
▲２▼「改質剤」
○改質剤は、前もって接着性樹脂と押出機やニ−ダ−等で溶融混練されていることが必須要件であり、これにより、以下に記載の効果が期待できる。
【００１３】
・改質剤の分散が高度で然も均一である。
・発泡粒子の表面に付与する改質効果の発現が容易に安定的に得られる。
・高速流動混合条件をきめ細かく制御しなくても改質効果が安定的に得られる。
・発泡粒子への改質剤定着工程が一段で済む。
・型内成形に用いる高倍率の発泡粒子（＝型内成形体）にしても改質剤の改質効果の低下が極めて少ない。
【００１４】
○改質剤は、押出造粒装置で接着性樹脂と溶融混練できるものであればその性状、即ち粉体、顆粒状、ペレット状、液体等どのような性状のものでも使用可能である。然も高濃度に接着性樹脂に溶融混練可能で、公知技術（特公平７−５３３８１号公報）よりも広範囲の改質剤に適用できる。
○改質剤として、導電性カーボンブラックがその添加濃度３〜１５重量％、好ましくは５〜１２重量％、更に好ましくは６〜１０重量％で使用できる。
・添加濃度が３重量％未満であると、導電性が発現しない。
・添加濃度が１５重量％を越えると、それ以上の効果が期待できないばかりか、接着性樹脂が脆くなり、摩擦等で発泡粒子（＝型内成形体）表面から欠落する。
【００１５】
○改質剤として、ＨＬＢが２〜１０、好ましくは２〜８、更に好ましくは３〜７の界面活性剤型帯電防止剤がその添加濃度０．５〜１０重量％、好ましくは１〜８重量％、更に好ましくは１．５〜７重量％で使用できる。
・ＨＬＢが２未満であると、帯電防止性能の発現水準が低く、場合によっては発現時間が遅くなったり、性能の持続性が乏しくなったりする。
・ＨＬＢが１０を越えると、融着性が悪化する。融着性を発現しょうとすると当然ながら添加濃度が低くなり帯電防止性能が発現しなくなる。
・添加濃度が０．５％未満であると、帯電防止性能が発現しない。例え発現したとしも、その維持性が低く耐久性にかける。
・添加濃度が１０重量％を超えると、それ以上の帯電防止性能が期待できないばかりか、発泡粒子間の融着性が低下し、機械的強度の低い型内成形しか得られなくなる。
【００１６】
○改質剤として、高分子型永久帯電防止剤がその添加濃度７〜５０重量％、好ましくは１０〜４０重量％、更に好ましくは１５〜３０重量％で使用できる。
・添加濃度が７重量％未満であると、帯電防止性能が発現しない。
・添加濃度が５０重量％を越えると、それ以上の効果が期待できない。
・高分子型永久帯電防止剤の種類は、ポリエーテルや第四級アンモニウム塩、そして、スルホン酸等の導電性ユニットを組み込んだポリオレフィン系樹脂の高分子型永久帯電防止剤を用いることができ特に限定されるものではないが、第四級アンモニウム塩系が帯電防止性能の発現性の点から好ましい。
【００１７】
▲３▼「改質剤を含む接着性樹脂の粉砕粉体」
○粉砕粉体の粒径は１０〜１４５メッシュ篩い（パス）、好ましくは２０〜１２０メッシュ、篩い（パス）更に好ましくは２８〜１００メッシュ篩い（パス）である。
・粒径が１０メッシュ篩い（パス）未満であると、発泡粒子表面への接着個数が少なくなり、発泡粒子の全表面に均一に分散融着させることが困難となる。また、混合時間が長くなって生産性、経済性が低下する。
・粒径が１４５メッシュ篩い（パス）を超えると、粉砕時間が長くなって加工コスト高となると共に取り扱い時に飛散し作業環境汚染となる。
【００１８】
○粉砕粉体のメルトフローレートは、３〜８０ｇ／１０分、好ましくは３〜７０、更に好ましくは４〜６０ｇ／１０分である。
・該メルトフローレートが３ｇ／１０分未満であると、高速剪断混合時の溶融粘度が高くなり、粒子表面へ定着しない。又、定着したとしても定着状態が不均一となる。
・該メルトフローレートが８０ｇ／１０分を越えると、それ以上の効果は期待できない。
○粉砕粉体の融点は、発泡粒子の融点の−３０℃〜−３℃、好ましくは−２５℃〜−５℃、更に好ましくは−２０℃〜−６℃である。
・融点が−３０℃未満であると、得られる発泡粒子（＝型内成形体）の耐熱性が低下する。また、改質剤を定着した発泡粒子の高速流動混合機から排出する迄の冷却時間が長くなり不経済である。そして、改質剤を押出機やニ−ダ−等で接着性樹脂と混練後この細粒ペレットを粉砕する方法が常温粉砕では不可能となり、液体窒素を使った低温粉砕が必要となるために不経済となる。
・融点が−３℃を超えると、加熱調温温度が発泡粒子の融点近傍となって、発泡粒子が熱収縮し、得られる粒子の倍率が極度に低下する。
【００１９】
○粉砕粉体の発泡粒子への溶融被覆量は、発泡粒子の重量に対して１〜１５重量％、好ましくは１．５〜１２重量％、更に好ましくは２〜１０重量％である。
・溶融被覆量が１重量％未満であると、発泡粒子の全表面に渡って定着（被覆）できずに不均一となる。
・溶融被覆量が１５重量％を超えると、それ以上の効果が期待できないし、発泡粒子表面に一時的に定着したとしても、流動混合時の摩擦で、混合中に削り取られたり、又、発泡粒子の表面積に対して過剰な接着性樹脂が混合翼等にに付着して、却って発泡粒子の流動混合性が悪くなる。
○粉砕粉体の接着性樹脂としては、発泡粒子と同種のポリオレフィン系樹脂が使用できる。その他、具体的には塩素化ポリエチレン、アクリル酸やアクリル酸エステルとエチレンとの共重合樹脂も使用できる。しかし一般実用上では発泡粒子に使用した樹脂と同種のものが選ばれる。この場合、溶融時の流動性を高めるために低分子量ポリエチレンワックスや石油系樹脂を併用しても良い。
【００２０】
▲４▼「高速流動混合機での溶融被覆」
高速剪断型混合機を使用すると混合時間が短く、生産性が高いため経済的である。
【００２１】
▲５▼「型内の加熱は、発泡粒子の融点の＋２℃〜＋１２℃の範囲の温度の水蒸気加熱」
○型内の加熱は、発泡粒子の融点の＋２℃〜＋１２℃の範囲の温度が必要である。
・型内加熱が発泡粒子の融点＋２℃未満では、粒子の体積膨張が部分的に不充分になり粒子間にすき間が生じたり、粒子間相互の融着が不充分になって成形体としての必要特性が悪化してしまう傾向にある。
・型内加熱が発泡粒子の融点＋１２℃を超える温度では、得られる成形体にひけ不良が生じ易い。又、得られる成形体の圧縮強度や回復性等が低下してしまう。
・こうした両者の調和を図り良質の成形体を得たいとする観点からは、型内での加熱温度は、発泡粒子の融点＋３℃〜＋１０℃の範囲の温度にすることが望ましい。
【００２２】
次に、本発明で使用する特性値及び評価方法を以下に示す。
（発泡粒子及び改質剤を含む接着性樹脂の粉砕粉体の特性）
１）発泡倍率；
重量（ｇ）既知の発泡粒子の体積（ｃｍ³）を水没法で測定し、その体積を重量で除した値を発泡倍率（ｃｍ³／ｇ）とする。
２）融点；
パーキンエルマー社製の示差走査熱量計ＤＳＣ７を用いて測定する。
発泡粒子及び改質剤を含む接着性樹脂の粉砕粉体１〜６ｍｇを上記装置にて１０℃／分の昇温速度で３０℃〜２００℃迄昇温し、２００℃に到達したら３０秒間放置した後、１０℃／分の降温速度で３０℃まで降温する操作を行った後、同様にして２回目の融解操作を行い、２回目の最大融解ピークの温度を融点とする。
３）メルトフローレート；
東洋精機製の溶融流動性試験機を用いてＡＳＴＭＤ１２３８の試験方法により評価し、温度１９０℃、荷重２．１６Ｋｇｆの条件下でダイより押し出される樹脂量を１０分間の流出重量に換算した値をメルトフローレートとする。
（型内成形体の特性）
４）倍率；
重量（ｇ）既知の型内成形体の体積（ｃｍ³）を水没法で測定し、その体積を重量で除した値を倍率（発泡倍率）（ｃｍ³／ｇ）とする。
５）改質効果；
５）−１導電性；
温度２３℃、相対湿度５０％に制御されている室内に、２４時間放置して状態調節された型内成形体の表面に、銅製電極（直径３８ｍｍ、高さ４１ｍｍ）を中心間距離８８ｍｍの間隔で載せて、二個の電極間に生じる電気抵抗値を横河製ディジタル絶縁抵抗計Ｍｏｄｅｌ３２１３Ｄで測定し評価する。
【００２３】
５）−２帯電防止性；
温度２３℃、相対湿度５０％に制御されている室内に、２４時間放置して状態調節された型内成形体（片面が成形スキンを有する厚みが５ｍｍの試料）をＪＩＳＫ６９１１の試験法５．１３項に規定する電極間にセットし、成形スキン面の表面抵抗を抵抗計（横河ヒューレット・パッカード社製ＨｉｇｈＲｅｓｉｓｔａｎｃｅＭｅｔｅｒ４３２９Ａ、印加電圧５００Ｖ）で測定し、ＪＩＳに規定する計算式から表面抵抗率を算出し評価する。
６）改質剤の定着力
６）−１耐摩擦性
接着性樹脂中に含まれている改質剤の脱落性を評価するもので、下記の方法で評価する。
【００２４】
〔摩擦条件〕
・摩擦子；
アクリル樹脂製平板（幅１００ｍｍ、長さ２５ｍｍ、厚さ５ｍｍ）に、密度が０．０２５ｇ／ｃｍ³、厚さが１０ｍｍの軟質ポリウレタン発泡体を貼り付け、その上に晒し綿布を取り付けたものを摩擦子に用いた。尚、荷重は０．０１ＭＰａとなるように調整した。
・摩擦試験
平坦な摩擦台に固定した型内成形体の上に、上記摩擦子を載せて、１００往復の摩擦を行う（摩擦速度３０往復／分、摩擦ストローク１５０ｍｍ）。
【００２５】
〔評価尺度〕
摩擦子に取り付けた晒し綿布に付着している改質剤の状態を目視で観察し評価する。
【表１】

６）−２耐剥離性
発泡粒子の表面に定着している改質剤を含む接着性樹脂の接着力を評価するもので、下記の方法で評価する。
【００２６】
型内成形体の表面に透明プラスチック粘着テープ（ＯＰＰ粘着テープＦＰ３７、商品名；（株）ケイユー製、幅５０ｍｍ）を、長さ２００ｍｍに渡って空気を抱き込まないように貼り合わせ、その上をガーゼを介して強く押圧しながら５回擦る。そして、テープの幅及び長さ方向に５ｍｍ間隔の標線を描き、このテープを引張剥離試験装置（剥離角度１８０度、剥離速度２ｍ／分）を用いて型内成形体から引き剥がして、粘着テープに付着している改質剤の状態を目視で観察し評価する。
【００２７】
〔評価尺度〕
テープの長さ方向中央部に位置する１００目（５ｃｍ×５ｃｍの面積）に於いて、１目の面積の１／３以上に渡って改質剤が付着している目の数を目視で観測し、１００目（全体）に対する百分率（％）で評価する。
【表２】

以下、本発明の内容を実施例を用いて詳述するが、これらは本発明の範囲を制限するものではない。
【００２８】
【実施例１、比較例１】
高速流動型混合機（スーパーミキサＳＭＶ−５００、商品名；（株）カワタ製、回転数：インバーター制御無断変速１００〜９００ｒｐｍ、温度検出端：案内板下部にＪ型φ１ｍｍ取り付け、ジャケット：３０℃水を循環通水）の槽内に架橋型ポリエチレン発泡粒子（メフＬＤ、商品名；旭化成工業（株）製、融点１１７℃、倍率４ｃｍ³／ｇ）を嵩体積で０．４ｍ³投入し、回転数を９００ｒｐｍにして高速回転の混合翼と発泡粒子との流動摩擦熱で発泡粒子の表面温度が１１０℃に到達するまで混合を続けた後、直ちに回転数を４００ｒｐｍに減速すると同時に、下記に示すところの改質剤を溶融混練した接着性樹脂の粉砕粉体（６０メッシュ篩いパス品）を上記発泡粒子の重量に対して３重量％量を１分かけて少しづつ供給し、供給開始から７分間混合して発泡粒子の表面に接着性樹脂の粉砕粉体を溶融被覆した。尚、混合中は発泡粒子の表面温度が１１０℃を越えないように混合機本体の蓋部に設けられた送風口より送風調温した。
【００２９】
その後、回転数を２００ｒｐｍに減速し、然も断続的な混合下で、蓋部送風口より連続送風して、発泡粒子の表面温度が１００℃に降温するまで冷却して取り出した。
得られた発泡粒子の表面状態は、拡大倍率１０倍の拡大投影機で観察した結果、本発明のメルトフローレートが５．２ｇ／１０分の粉体が溶融被覆された発泡粒子（実施例１）は、粒子表面全体に渡って黒色の接着性樹脂が均一に被覆されていたが、メルトフローレートが１ｇ／１０分以下の粉体が溶融被覆された発泡粒子（比較例１）は、粒子の一部に点々と少ししか付着していない状態であった。念のために比較例１の発泡粒子を取り出した後の混合機槽内を観察した結果、槽の底には発泡粒子表面に溶融被覆されなかった接着性樹脂の粉体が、０．１〜２ｍｍ程度の固まりになって散在していた。
【００３０】
（改質剤を溶融混練した接着性樹脂の粉砕粉体の作製）
二軸押出機による樹脂ペレット製造装置を使用して、接着性樹脂は、溶融流動性が異なる２種の低密度ポリエチレン（サンテック−ＬＤ、Ｍグレード、商品名；旭化成工業（株）製、融点１０４℃、メルトフローレート２８、５５ｇ／１０分）とし、このポリエチレンに改質剤として導電性カーボンブラック（ケッチンブラックＥＣ−６００ＪＤ、商品名；ライオン（株）製）を７重量％含有するペレットをそれぞれ作製し、このペレットを常温粉砕機で粉砕して、６０メッシュ篩い（パス）の粉体を得た。
この粉体について、本文記載の評価方法で評価したメルトフローレートは、前者は１ｇ／１０分以下と溶融流動性が極度に悪いものであったが、後者は５．２ｇ／１０分で良好な流動性を示すものであった。
【００３１】
次に、本発明（実施例１）と「公知技術（特公平７−５３３８１号公報）」（下記に示す）の発泡粒子に於いて、改質剤（導電性カーボンブラック）を含む接着性樹脂がどのように発泡粒子の表面に定着しているかを電子顕微鏡を用いて観察した。その構造解析結果を図２（本発明；実施例１）、図３（「公知技術（特公平７−５３３８１号公報」）に示す。
【００３２】
図２の結果によると、接着性樹脂中の導電性カーボンブラックは、高度に分散していて、この導電性カーボンブラックを含む接着性樹脂は、発泡粒子の表面に直接、密に定着されていることが判る。図３の導電性カーボンブラックは、その製造方法から明らかなように接着性樹脂（接着層）を介して接着性樹脂中に分散されいる。その分散状態は、前もって接着性樹脂中に溶融混練した図２のものより遙かに分散度が悪く不均一であり、又、導電性カーボンブラックが発泡粒子の上部の接着性樹脂（接着層）に潜りこんでいることも判る。
発泡粒子の基材樹脂と接着性樹脂との違いは、ラメラの厚みで判断できる。即ち、発泡粒子の基材樹脂は、融点（＝密度）が高いために、接着性樹脂のラメラ厚み〜８ｎｍより厚い１０〜１２ｎｍであることから容易に判断できる。
【００３３】
（電子顕微鏡による構造解析の方法）
１）試料の前処理
包系埋用エポキシ樹脂をゼラチンカプセルに入れ、硬化させた上に試料をエポキシ系接着剤で固定し、観察部を剃刀でトリミング後、液体窒素で冷却しながらそのトリミング面をガラスナイフで鏡面に仕上げて、ＲｕＯ₄で蒸気染色（１％ＲｕＯ₄水溶液）を一夜施してからウルトラミクロトーム（ダイヤモンドナイフ使用）で６０ｎｍ程度の超薄切片を作成し、この超薄切片をコロジオン膜を張った検鏡用グリッドに載せ、カーボンを６ｎｍ程度コーティングして検鏡試料とした。
２）観察；
透過型電子顕微鏡（日立製作所製Ｈ−５００、加速電圧１００ｋｖ）を用いて観察した。
【００３４】
【実施例２】
実施例１の「改質剤を溶融混練した接着性樹脂の粉砕粉体の作製」に於いて、接着性樹脂を、低密度ポリエチレン（サンテック−ＬＤ、Ｍグレード、商品名；旭化成工業（株）製、融点１０４℃、メルトフローレート４５ｇ／１０分）と低分子量ポリエチレンワックス（ネオワックス、商品名；ヤスハラケミカル（株）製、融点１０９℃）との混合系（低密度ポリエチレン／低分子量ポリエチレンワックス＝９５／５〜８０／２０）とした他は実施例１と同様にして、本文記載のメルトフローレートが３．３、８．５、１２ｇ／１０分を示すところの接着性樹脂の粉砕粉体が発泡粒子の表面に溶融被覆された３種類の発泡粒子を作製した結果、得られた全ての粒子は、その表面全体に渡って黒色の接着性樹脂が均一に被覆されていて、発泡粒子表面が白く露出している部分は全く観察されなかった。
【００３５】
【実施例３、比較例２】
実施例１と下記に示す処の「公知技術（特公平７−５３３８１号公報）」で得られた発泡粒子を、加圧（高圧空気）・加温装置を有するオートクレーブ内に収容し、８０℃の温度下で１時間かけて昇圧し、圧力１．５ＭＰａ（ゲージ圧）で８時間保持して発泡粒子の内圧を高める再膨張能処理を行った後、発泡装置に収容して圧力が０．０６ＭＰａ（ゲージ圧）の加熱水蒸気で１５秒間加熱発泡し、発泡倍率が９ｃｍ³／ｇの二次発泡粒子とした。更にこの二次発泡粒子を上記と同様にして、加熱水蒸気圧力を０．０４〜０．０６５ＭＰａ（ゲージ圧）の範囲で調整しながら発泡倍率が２２、３２、４３ｃｍ³／ｇの三次発泡粒子とした。
この二次、三次発泡粒子をそれぞれ水蒸気孔を有する型内成形金型内（内寸法；３０ｃｍ×３０ｃｍ×２．５ｃｍｔ）に型開き充填（注）（型開き幅；８．３〜１４．７ｍｍ）し、圧力０．１１ＭＰａ（ゲージ圧）の加熱水蒸気で加熱した後、冷却し金型内から取り出し、室温が８０℃の乾燥室に１２時間放置して型内成形体（実施例３、比較例２）とした。〔（注）：発泡粒子間の空隙部体積に相当する量だけ型を開いた状態で発泡粒子を型内充填し、充填完了後に正規の位置まで型閉めを行う充填方法〕
【００３６】
得られた型内成形体（実施例３、比較例２）について、本文記載の評価方法により導電性、改質剤の定着力を評価し、その結果を表１、図１に示す。
表１の結果によると、本発明の発泡粒子及びその型内成形体（実施例３）は、導電性に優れ且つ、改質剤の定着力も優れていることが判る。
更に、図１の結果によると、本発明の発泡粒子及びその型内成形体は、導電性が型内成形体の倍率によって変化する度合いが極めて小さく、高倍率の成形体でも優れた導電性を発現することが判る。
又、本発明の発泡粒子は、改質剤の定着加工の時間が短くて済み経済性に富んだ発泡粒子であることも判る。
【００３７】
「公知技術（特公平７−５３３８１号公報）」の説明
本例は、改質剤を予め接着性樹脂と溶融混練せずに、そのまま発泡粒子の表面に直接被覆した発泡粒子、及び型内成形体の評価を示すものである。尚、改質剤は被覆時の分散性を考慮して微粉体を用いた。
即ち、高速流動型混合機（スーパーミキサＳＭＶ−５００、商品名；（株）カワタ製、回転数：インバーター制御無断変速１００〜９００ｒｐｍ、温度検出端：案内板下部にＪ型φ１ｍｍ取り付け、ジャケット：３０℃水を循環通水）の槽内に架橋型ポリエチレン発泡粒子（メフＬＤ、商品名；旭化成工業（株）製、融点１１７℃、倍率４ｃｍ³／ｇ）を嵩体積で０．４ｍ³投入し、回転数を９００ｒｐｍにして高速回転の混合翼と発泡粒子との流動摩擦熱で発泡粒子の表面温度が１１０℃に到達するまで混合を続けた後、直ちに回転数を４００ｒｐｍに減速すると同時に、接着性樹脂の粉砕粉体として、低密度ポリエチレン（サンテック−ＬＤ、Ｍグレード、商品名；旭化成工業（株）製、融点１０４℃、メルトフローレート５５ｇ／１０分、６０メッシュ篩いパス品）を、上記発泡粒子の重量に対して２．７９重量％量の半分を１分かけて少しづつ供給し、供給開始から４分間混合して発泡粒子の表面に接着性樹脂を溶融被覆した。その後、改質剤として導電性カーボンブラック（ケッチンブラックＥＣＰ−６００ＪＤ、商品名；ライオン（株）製 ※実施例１、比較例１に使用したものの微粉砕品）を上記接着性樹脂の全重量に対して７．５３重量％量を０．５分かけて少しづつ供給し、供給開始から１．５分間混合して当該粒子表面の接着性樹脂にまぶし付けて絡み合わせた後、残り半分の接着性樹脂を１分かけて少しづつ供給し、供給開始から８分間混合した。
尚、混合中は発泡粒子の表面温度が１１０℃を越えないように混合機本体の蓋部に設けられた送風口より送風調温した。
【００３８】
その後、回転数を２００ｒｐｍに減速し、然も断続的な混合下で、蓋部送風口より連続送風して、発泡粒子の表面温度が１００℃に降温するまで冷却して取り出した。
得られた発泡粒子の表面状態は、実施例１と同様に拡大倍率１０倍の拡大投影機で観察した結果、粒子表面全体に渡って改質剤が均一に被覆されていることが観察された。
【００３９】
【実施例４】
実施例１の「改質剤を溶融混練した接着性樹脂の粉砕粉体の作製」を下記に示すものに、そして発泡粒子への被覆供給量を発泡粒子の重量に対して７重量％量とした他は、実施例１と同様にして、界面活性剤型帯電防止剤を溶融混練した接着性樹脂の粉砕粉体を発泡粒子の表面に溶融被覆された発泡粒子を得た。
得られた発泡粒子の表面状態は、拡大倍率１０倍の拡大投影機で観察した結果、粒子表面全体に渡って赤色の接着性樹脂が均一に被覆されていた。
この発泡粒子を実施例３に従って、発泡倍率が３２ｃｍ³／ｇの三次発泡粒子とした後、型内成形を行って倍率が３０ｃｍ³／ｇの型内成形体とした。
【００４０】
得られた型内成形体について、本文記載の評価方法により帯電防止を評価した結果、表面抵抗率は２．６×１０¹¹Ωの優れた帯電防止性を有していた。又、耐摩擦性と耐剥離性についても評価したが実用性に優れるものであった。
（改質剤を溶融混練した接着性樹脂の粉砕粉体の作製）
単軸押出機による樹脂ペレット製造装置を使用して、接着性樹脂は低密度ポリエチレン（サンテック−ＬＤ、Ｍグレード、商品名；旭化成工業（株）製、融点１０４℃、メルトフローレート５５ｇ／１０分）とし、このポリエチレンに改質剤として界面活性剤型帯電防止剤（デノン２２２０、商品名；丸菱油化工業（株）製、ＨＬＢ４．６）を５重量％含有するペレットをそれぞれ作製した。尚、着色剤として赤顔料（クロモフタールスカーレットＲ０．０６重量％）を同時に添加した。このペレットを常温粉砕機で粉砕して、４０メッシュ篩い（パス）の粉体を得た。この粉体について、本文記載の評価方法で評価したメルトフローレートは、５３ｇ／１０分で良好な流動性を示すものであった。
参考として、
【００４１】
【比較例３】
上記「公知技術（特公平７−５３３８１号公報）」の接着性樹脂の粉砕粉体にタンブラー型ブレンダーを用いて着色剤の赤顔料（クロモフタールスカーレットＲ０．０６重量％）を添加混合したものを発泡粒子の重量に対して６．６５重量％量用い、又改質剤を実施例４の界面活性剤型帯電防止剤とし、且つ供給量を接着性樹脂の全重量に対して５．２６重量％量とした他は、「公知技術（特公平７−５３３８１号公報）」と同様にして行った結果、改質剤である界面活性剤型帯電防止剤の殆どが混合機の槽壁に付着してしまい、発泡粒子の表面に界面活性剤型帯電防止剤が優先的に溶融被覆された発泡粒子を得ることができなかった。
【００４２】
【実施例５】
実施例１の「改質剤を溶融混練した接着性樹脂の粉砕粉体の作製」に於いて、接着性樹脂を、低密度ポリエチレン（サンテック−ＬＤ、Ｍグレード、商品名；旭化成工業（株）製、融点１０４℃、メルトフローレート４５ｇ／１０分）とし、このポリエチレンに改質剤として高分子型永久帯電防止剤（レオレックスＡＳ−１７０、商品名；第一工業製薬（株）製）を３０重量％含有するペレットとした他は実施例１と同様にして、本文記載の評価方法で評価したメルトフローレートが８０ｇ／１０分を示す粉体を得た。尚、着色剤として赤顔料（クロモフタールスカーレットＲ０．０６重量％）を同時に添加した。
この粉体を用いて、実施例１と同様にして、発泡粒子の表面に改質剤として高分子型永久帯電防止剤を含む接着性樹脂が定着した発泡粒子とした。但し、接着性樹脂の粉砕粉体の供給量は、発泡粒子の重量に対して８重量％量とした。
【００４３】
この後、この発泡粒子を実施例３と同様に水蒸気孔を有する型内成形金型に充填し、型内成形体とした。
得られた型内成形体は、倍率が４ｃｍ³／ｇで高強度を有し、本文記載の方法により帯電防止性を評価したところ表面抵抗率が６．２×１０¹⁰Ωという高水準の帯電防止性能を有していた。又、改質剤の定着力についてもその評価は実用性に富む優れたものであった。
尚、本型内成形体の機能は、帯電防止性の持続性を目的とするものであり、その評価の一例として、繰返し水洗による帯電防止性の劣化を評価した。即ち、台所用洗剤（ママローヤル、商品名；ライオン（株）製）の０．１５体積％濃度の水溶液中で、軟質ウレタンスポンジ（嵩密度０．０２５ｇ／ｃｍ³）を用いて成形体表面を２０回洗浄し水洗後、２５℃の送風循環恒温槽内で乾燥したものを、本文記載の評価方法で帯電防止性を評価した結果、この操作を２０回繰り返した後でも、洗浄前と同じ値の表面抵抗率を維持していた。
【００４４】
参考例として、従来技術の方法即ち、低密度ポリエチレン（サンテックＬＤ、商品名；旭化成工業（株）製、融点１１７℃）に上記の高分子型永久帯電防止剤を２５重量％添加した、直径が０．９ｍｍ、長さが１．２ｍｍの押出造粒ミニペレットを作製し、このミニペレットに水懸濁系でジクミルパーオキサイド（架橋剤）を含浸させ１６０℃で４５分間の架橋反応を行って、架橋ポリエチレン樹脂粒子とした。この粒子を公知の方法で、ブタンガスを含浸した後、発泡装置を用いて発泡倍率が４ｃｍ³／ｇの架橋ポリエチレン発泡粒子を得ようとしたが、気泡構造が不均一で然も発泡倍率が２ｃｍ³／ｇ以下の微発泡粒子しか得られず、到底発泡膨張能が期待できないものであった。
【００４５】
【表３】

【００４６】
【発明の効果】
本発明によれば、高度且つ熟練度の高い技術を要することなく、しかも１工程で簡単に、導電性や帯電防止性及び難燃性等の各種機能を有する改質剤をポリオレフィン系樹脂発泡粒子の表面に定着した機能性ポリオレフィン系樹脂発泡粒子を得ることができ、そしてこれを用いて優れた機能を有する型内成形体をより経済的に提供できるという、格別顕著な効果を奏することができる。
【図面の簡単な説明】
【図１】本発明（実施例３）及び比較例２（「公知技術（特公平７−５３３８１号公報）」）により成形された型内成形体の発泡倍率と導電率の関係を示すグラフである。
【図２】本発明（実施例１）により成形された改質剤（導電性カーボンブラック）を含む接着性樹脂が溶融被覆された発泡粒子の表面状態を示す概念図である。
【図３】「公知技術（特公平７−５３３８１号公報）」により成形された改質剤（導電性カーボンブラック）を含む接着性樹脂が溶融被覆された発泡粒子の表面状態を示す概念図である。
【符号の説明】
１、１’：導電性カーボンブラック
２、２’：接着性樹脂
２”：接着性樹脂（接着層）
３、３’：ポリエチレン発泡粒子（表皮部）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a functional polyolefin resin foamed particle in which a modifier having various functions such as conductivity, antistatic property and flame retardancy is fixed on the surface of the polyolefin resin foamed particle, and improvement of the in-mold molded product thereof And a manufacturing method thereof.
[0002]
[Prior art]
In recent years, electronic and electrical related devices, particularly personal computers and peripheral devices such as liquid crystal display devices and storage devices are fields that have been growing rapidly with the development of information culture represented by the Internet.
Since these devices incorporate semiconductor products such as LSI and are prone to electrostatic breakdown, these buffer packaging materials for transport have not only high-performance buffer performance, but also conductivity and antistatic performance. In the present situation, a cushioning material for a foamed molded article of polyolefin resin having a function such as the above is required, and its importance is increasing more and more.
[0003]
For example, as a polyolefin resin-in-mold foam-molded article having electrical conductivity, conductive carbon black is used as a modifier for imparting conductivity to polyolefin resin in an extrusion granulator at a high concentration of 10 to 20 parts. Resin particles that have been kneaded are made into expanded particles by a known method, and a conductive in-mold molded body obtained by in-mold molding of the expanded particles is provided, but because it contains a large amount of inorganic conductive carbon black. The mechanical strength such as tensile strength and tear strength is low, and the foam film of foamed particles has a myriad of minute defects, and the closed cell ratio is extremely low. It has poor properties and has a fatal drawback as a cushioning material.
[0004]
In order to eliminate this drawback, a conductive in-mold molded product of polyolefin resin expanded particles is disclosed in Japanese Patent Publication No. 7-53381.
In order to fix the conductive carbon black on the surface of the heated and temperature-controlled foamed particles by using a high shear mixer, this in-mold molded body is formed by first forming an adhesive resin layer and then applying the conductive carbon black. The foamed particles obtained by entanglement with the adhesive resin in the sprinkled and melted state and further coated with the adhesive resin are molded in-mold.
The properties of this molded body are high fusion between the foamed particles, excellent recovery, and a surface resistance of 10^FourΩ-10¹³This is an in-mold molded product of polyolefin resin expanded particles having a wide range of performance from the conductive level of Ω to antistatic properties.
[0005]
[Problems to be solved by the invention]
However, since the foamed particles used in the in-mold molded product are dispersed in the adhesive resin of the modifier under high shear mixing, the shape of the mixing blade is not good enough to obtain foam particles in a good dispersion state. In addition to being limited, high shear mixing conditions such as the surface temperature of the expanded particles, the rotational speed of the mixing blade and the mixing time must be controlled within a very narrow range, which requires advanced and highly skilled technology and If it is out of the condition range, the uniform dispersion of the modifying agent is insufficient, so that the intended reforming effect is not exhibited or the appearance quality is deteriorated.
[0006]
Further, when trying to obtain an in-mold molded body in which the modifier is firmly fixed on the surface of the expanded particles, the step of fixing the modifier on the surface of the expanded particles includes 1) forming the adhesive resin layer, 2 Since the three steps of the modifier spraying step and the modifier fixing strengthening step are essential, there is a problem that the operation is complicated, the processing cycle is long, and the economy is low. In addition, the modifier is a fine powder, especially bulky conductive carbon black can be easily scattered during handling, contaminating the surrounding machinery and equipment, and inhaling into the body during breathing, which can harm health. There is.
[0007]
[Means for Solving the Problems]
The present invention is as follows.
1. A method for producing a functional polyolefin resin foam particle in which an adhesive resin containing a modifier is fixed on the surface of a polyolefin resin foam particle, and using a high-speed flow mixer, the surface of the polyolefin resin foam particle is The melting point of the adhesive resin obtained by melt-kneading a modifier having a melting flowability of -30 ° C. to -3 ° C. of the above-mentioned expanded particle melting point and a melt flow rate of 3 to 80 g / 10 min. A method for producing functional polyolefin resin expanded particles, wherein the pulverized powder is melt-coated by 1 to 15% by weight based on the weight of the expanded particles.
2. The pulverized powder of the adhesive resin has a particle size of 10 to 145 mesh sieve (pass). The manufacturing method of the functional polyolefin resin expanded particle of description.
3. The modifier is conductive carbon black, and the concentration of the modifier is 3 to 15% by weight based on the weight of the adhesive resin. Or 2. The manufacturing method of the functional polyolefin resin expanded particle of description.
4). The modifying agent is a surfactant type antistatic agent having an HLB of 2 to 10, and the addition concentration thereof is 0.5 to 10% by weight based on the weight of the adhesive resin. . Or 2. The manufacturing method of the functional polyolefin resin expanded particle of description.
5. The above modifier is a polymer-type permanent antistatic agent of polyolefin resin, and its addition concentration is 7 to 50% by weight with respect to the weight of the adhesive resin. Or 2. The manufacturing method of the functional polyolefin resin expanded particle of description.
The functional polyolefin resin expanded particles of the present invention are functional polyolefin resin expanded particles in which an adhesive resin containing a modifier is fixed on the surface of the polyolefin resin expanded particles, preferably using a high-speed fluidized mixer. A modification in which the melting point of the foamed polyolefin-based resin particles is in the range of −30 ° C. to −3 ° C. of the melting point of the expanded particles and the melt flow rate is 3 to 80 g / 10 min. The adhesive resin pulverized powder obtained by melting and kneading the agent is melt-coated by 1 to 15% by weight based on the weight of the foamed particles. The pulverized powder of the adhesive resin preferably has a particle size of 10 to 145 mesh sieve (pass). The modifier is preferably conductive carbon black, and the concentration of the modifier is preferably 3 to 15% by weight based on the weight of the adhesive resin. Further, the modifier is a surfactant type antistatic agent having an HLB of 2 to 10, and the addition concentration is preferably 0.5 to 10% by weight with respect to the weight of the adhesive resin. Further, the modifier is a polymer type permanent antistatic agent of polyolefin resin, and the addition concentration thereof is preferably 7 to 50% by weight with respect to the weight of the adhesive resin.
[0008]
The in-mold molded product of the present invention is heated by filling any of the above functional polyolefin resin expanded particles in the mold, preferably water vapor having a temperature in the range of + 2 ° C. to + 12 ° C. of the melting point of the expanded particles. The magnification obtained by heating and fusing the particles to each other is 5 to 55 cm.^Three/ G functional polyolefin-based resin foam-in-mold molded product.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, each configuration of the present invention will be divided into items and will be described in detail with reference to the drawings, tables, and the like.
[0010]
(1) “Polyolefin resin foamed particles”
○ A generic term for crosslinked and non-crosslinked types.
○ Polyolefin resins include low, medium, high density polyethylene, linear low density polyethylene, ultra high density polyethylene, polyethylene of metallocene catalyst, ethylene resin represented by ethylene-vinyl acetate copolymer, polypropylene, The copolymer component is a random or block copolymer resin with propylene which is one or more of ethylene, butene-1, 4-methylpentene-1, or the like, or a mixed resin in which two or more of these are blended.
[0011]
○ The expansion ratio of expanded particles is 3cm^Three/ G-15cm^Three/ G, preferably 4 cm^Three/ G-10cm^Three/ G.
・ Foaming ratio is 3cm^ThreeIf it is less than / g, sequential high foaming work for use in in-mold molding (high magnification) becomes multistage, and the foam molding production process is complicated and uneconomical.
・ Foaming ratio is 15cm^ThreeIf it exceeds / g, the weight of one foamed particle becomes light, and the generation of frictional heat during high-speed fluidized mixing becomes insufficient, the temperature rise time becomes long, and the fixing of the modifier becomes nonuniform. In addition, the heat heated near the melting point of the expanded particles shrinks, the reduction in magnification becomes remarkable, and the weight charged into the mixing tank is reduced, which makes the processing uneconomical.
[0012]
(2) “Modifier”
O It is essential for the modifier to be melt-kneaded with an adhesive resin and an extruder or kneader in advance, whereby the effects described below can be expected.
[0013]
-The dispersion of the modifier is high and uniform.
-The expression of the modification effect imparted to the surface of the expanded particles can be obtained easily and stably.
-The reforming effect can be obtained stably without finely controlling the high-speed fluid mixing conditions.
・ One step of fixing the modifier to the expanded particles.
-Even in the case of high-magnification expanded particles (= in-mold molded product) used for in-mold molding, the degradation effect of the modifier is extremely small.
[0014]
As long as the modifier can be melt-kneaded with the adhesive resin in an extrusion granulator, any properties such as powder, granule, pellet, liquid, etc. can be used. However, it can be melt kneaded into the adhesive resin at a high concentration, and can be applied to a wider range of modifiers than the known technique (Japanese Patent Publication No. 7-53381).
As a modifier, conductive carbon black can be used at an addition concentration of 3 to 15% by weight, preferably 5 to 12% by weight, more preferably 6 to 10% by weight.
-When the addition concentration is less than 3% by weight, conductivity is not exhibited.
When the additive concentration exceeds 15% by weight, not only the effect can be expected, but also the adhesive resin becomes brittle and is lost from the surface of the expanded particles (= in-mold molded product) due to friction or the like.
[0015]
As a modifier, a surfactant type antistatic agent having an HLB of 2 to 10, preferably 2 to 8, more preferably 3 to 7 is added at a concentration of 0.5 to 10% by weight, preferably 1 to 8% by weight. %, More preferably 1.5 to 7% by weight.
-If HLB is less than 2, the level of antistatic performance will be low, and depending on the case, the onset time may be delayed or the sustainability of the performance will be poor.
-When HLB exceeds 10, fusion property will deteriorate. When trying to develop the fusing property, the addition concentration is naturally lowered and the antistatic performance is not exhibited.
-When the additive concentration is less than 0.5%, antistatic performance does not appear. Even if they are expressed, their maintainability is low and they are put to durability.
When the additive concentration exceeds 10% by weight, not only antistatic performance beyond that can be expected, but also the fusion property between the expanded particles is lowered, and only in-mold molding with low mechanical strength can be obtained.
[0016]
As a modifier, a polymeric permanent antistatic agent can be used at an addition concentration of 7 to 50% by weight, preferably 10 to 40% by weight, more preferably 15 to 30% by weight.
-If the addition concentration is less than 7% by weight, antistatic performance does not appear.
-If the additive concentration exceeds 50% by weight, no further effect can be expected.
-The type of polymer type permanent antistatic agent can be a polyether type quaternary ammonium salt and a polyolefin type polymer type permanent antistatic agent incorporating a conductive unit such as sulfonic acid. Although not limited, a quaternary ammonium salt system is preferable from the viewpoint of the development of antistatic performance.
[0017]
(3) “Grinded powder of adhesive resin containing modifier”
The particle size of the pulverized powder is 10 to 145 mesh sieve (pass), preferably 20 to 120 mesh, sieve (pass), more preferably 28 to 100 mesh sieve (pass).
-When the particle size is less than 10 mesh sieve (pass), the number of adhesions to the surface of the expanded particles is reduced, and it becomes difficult to uniformly disperse and fuse the entire surface of the expanded particles. In addition, the mixing time becomes longer and the productivity and economy are lowered.
-If the particle size exceeds the 145 mesh sieve (pass), the grinding time becomes longer and the processing cost is increased, and it is scattered during handling and contaminates the working environment.
[0018]
The melt flow rate of the pulverized powder is 3 to 80 g / 10 minutes, preferably 3 to 70, and more preferably 4 to 60 g / 10 minutes.
-If the melt flow rate is less than 3 g / 10 min, the melt viscosity at the time of high-speed shear mixing will be high, and it will not be fixed to the particle surface. Even if the image is fixed, the fixed state is not uniform.
-If the melt flow rate exceeds 80 g / 10 min, no further effect can be expected.
The melting point of the pulverized powder is −30 ° C. to −3 ° C., preferably −25 ° C. to −5 ° C., more preferably −20 ° C. to −6 ° C.
-If the melting point is less than -30 ° C, the heat resistance of the resulting foamed particles (= in-mold molded product) decreases. In addition, the cooling time until the foamed particles with the modifier fixed are discharged from the high-speed fluid mixer is long, which is uneconomical. The method of pulverizing the fine pellets after kneading the modifier with an adhesive resin using an extruder or kneader becomes impossible at room temperature pulverization, and requires low-temperature pulverization using liquid nitrogen. It becomes uneconomical.
-When melting | fusing point exceeds -3 degreeC, heating temperature control temperature will become the melting | fusing point vicinity of foamed particle, a foamed particle will heat-shrink, and the magnification of the particle | grains obtained will fall extremely.
[0019]
The melt coating amount of the pulverized powder on the expanded particles is 1 to 15% by weight, preferably 1.5 to 12% by weight, more preferably 2 to 10% by weight, based on the weight of the expanded particles.
When the melt coating amount is less than 1% by weight, the entire surface of the expanded particles cannot be fixed (coated) and becomes non-uniform.
・ If the melt coating amount exceeds 15% by weight, no further effect can be expected, and even if temporarily fixed on the surface of the foamed particles, it may be scraped off during mixing due to friction during fluid mixing. Adhesive resin excessive with respect to the surface area of the particles adheres to the mixing blade and the like, and on the contrary, the flow mixing property of the foamed particles is deteriorated.
As the pulverized powder adhesive resin, the same type of polyolefin resin as the foamed particles can be used. In addition, specifically, chlorinated polyethylene, acrylic acid, a copolymer resin of acrylic acid ester and ethylene can also be used. However, in general practical use, the same type of resin used for the expanded particles is selected. In this case, a low molecular weight polyethylene wax or a petroleum resin may be used in combination in order to increase the fluidity at the time of melting.
[0020]
(4) "Melting coating with high-speed fluid mixing machine"
Use of a high-speed shear mixer is economical because the mixing time is short and the productivity is high.
[0021]
(5) “In-mold heating is steam heating at a temperature in the range of + 2 ° C. to + 12 ° C. of the melting point of the expanded particles”
○ Heating in the mold requires a temperature in the range of + 2 ° C. to + 12 ° C. of the melting point of the expanded particles.
・ If the in-mold heating is less than the melting point of the foamed particles + 2 ° C., the volume expansion of the particles is partially insufficient, resulting in gaps between the particles or insufficient fusion between the particles. Necessary characteristics tend to deteriorate.
-If the in-mold heating exceeds the melting point of the foamed particles + 12 ° C, the resulting molded product is liable to suffer from sink marks. Moreover, the compressive strength, recoverability, etc. of the obtained molded body will be reduced.
-From the standpoint of achieving a harmony between the two and obtaining a high-quality molded article, it is desirable that the heating temperature in the mold is a temperature in the range of the melting point of the expanded particles + 3 ° C to + 10 ° C.
[0022]
Next, characteristic values and evaluation methods used in the present invention are shown below.
(Characteristics of ground powder of adhesive resin containing expanded particles and modifier)
1) Foaming ratio;
Weight (g) Volume of known foam particles (cm^Three) Is measured by the submersion method, and the value obtained by dividing the volume by the weight is the expansion ratio (cm^Three/ G).
2) melting point;
Measurement is performed using a differential scanning calorimeter DSC7 manufactured by PerkinElmer.
1-6 mg of adhesive resin pulverized powder containing expanded particles and a modifier is heated from 30 ° C. to 200 ° C. at a heating rate of 10 ° C./min with the above apparatus, and left for 30 seconds when reaching 200 ° C. After performing the operation of lowering the temperature to 30 ° C. at a temperature lowering rate of 10 ° C./min, the second melting operation is performed in the same manner, and the temperature of the second maximum melting peak is defined as the melting point.
3) Melt flow rate;
Evaluated by ASTM D1238 test method using a Toyo Seiki melt fluidity tester, and the value obtained by converting the amount of resin extruded from the die under the conditions of a temperature of 190 ° C. and a load of 2.16 Kgf into an outflow weight of 10 minutes. The melt flow rate is used.
(Characteristics of in-mold molded product)
4) Magnification;
Weight (g) Volume of known in-mold molded product (cm^Three) Is measured by the submersion method, and the value obtained by dividing the volume by the weight is the magnification (foaming magnification) (cm^Three/ G).
5) Modification effect;
5) -1 conductivity;
A copper electrode (diameter: 38 mm, height: 41 mm) is placed at a distance of 88 mm between the centers on the surface of the in-mold molded body that has been allowed to stand for 24 hours in a room controlled at a temperature of 23 ° C. and a relative humidity of 50%. The electrical resistance value generated between the two electrodes is measured with a digital insulation resistance meter Model 3213D manufactured by Yokogawa and evaluated.
[0023]
5) -2 antistatic properties;
An in-mold molded product (a sample having a molded skin with a thickness of 5 mm on one side) that was left to stand for 24 hours in a room controlled at a temperature of 23 ° C. and a relative humidity of 50% was tested in accordance with test method 5.13 of JIS K6911. Set between the electrodes specified in the section, and measure the surface resistance of the molded skin surface with a resistance meter (High Resistance Meter 4329A manufactured by Yokogawa Hewlett-Packard Co., applied voltage 500 V), and calculate the surface resistivity from the calculation formula specified in JIS. Calculate and evaluate.
6) Fixing power of modifier
6) -1 Friction resistance
It evaluates the detachability of the modifier contained in the adhesive resin and is evaluated by the following method.
[0024]
[Friction conditions]
・ Friction;
An acrylic resin flat plate (width 100 mm, length 25 mm, thickness 5 mm) with a density of 0.025 g / cm^ThreeA soft polyurethane foam having a thickness of 10 mm was pasted, and a cotton cloth was attached to the soft polyurethane foam and used as a friction element. The load was adjusted to be 0.01 MPa.
・ Friction test
The friction element is placed on the in-mold molded body fixed to a flat friction table, and 100 reciprocating frictions are performed (friction speed 30 reciprocations / minute, friction stroke 150 mm).
[0025]
(Evaluation scale)
The condition of the modifier adhering to the exposed cotton cloth attached to the friction element is visually observed and evaluated.
[Table 1]

6) -2 Peel resistance
The adhesive strength of an adhesive resin containing a modifier fixed on the surface of the expanded particles is evaluated by the following method.
[0026]
A transparent plastic adhesive tape (OPP adhesive tape FP37, trade name; manufactured by Keiyu Co., Ltd., width 50 mm) is bonded to the surface of the molded body in the mold over a length of 200 mm so as not to entrap air, Rub 5 times while pressing firmly through the gauze. Then, a marked line with an interval of 5 mm is drawn in the width and length direction of the tape, and the tape is peeled off from the in-molded product using a tensile peeling test device (peeling angle 180 degrees, peeling speed 2 m / min). The state of the modifier adhering to the tape is visually observed and evaluated.
[0027]
(Evaluation scale)
At 100 eyes (5 cm x 5 cm area) located in the center of the tape in the longitudinal direction, visually observe the number of eyes to which the modifier is attached over 1/3 of the area of the eyes. Then, it is evaluated as a percentage (%) with respect to the 100th (whole).
[Table 2]

Hereinafter, the content of the present invention will be described in detail using examples, but these do not limit the scope of the present invention.
[0028]
Example 1 and Comparative Example 1
High-speed fluid mixer (Supermixer SMV-500, trade name: manufactured by Kawata Co., Ltd., rotation speed: inverter-controlled non-transmission 100 to 900 rpm, temperature detection end: J-type φ1 mm attached to the lower part of the guide plate, jacket: 30 ° C. water In the tank of circulating water) Cross-linked polyethylene foam particles (Mef LD, trade name; manufactured by Asahi Kasei Kogyo Co., Ltd., melting point 117 ° C., magnification 4 cm)^Three/ G) is 0.4 m in bulk volume^ThreeThe mixing is continued until the surface temperature of the foamed particles reaches 110 ° C. due to the fluid frictional heat between the mixing blade and the foamed particles rotating at a high speed and the rotational speed of 900 rpm. Then, a ground powder (60 mesh sieve pass product) of an adhesive resin obtained by melting and kneading the modifier as described below is supplied little by little over 1 minute with respect to the weight of the foamed particles, The mixture was mixed for 7 minutes from the start of supply, and the surface of the foamed particles was melt-coated with the ground powder of the adhesive resin. During mixing, the temperature of the foamed particles was controlled from the air outlet provided in the lid of the mixer main body so that the surface temperature of the foamed particles did not exceed 110 ° C.
[0029]
Thereafter, the number of revolutions was reduced to 200 rpm, and continuously blown from the lid air outlet under intermittent mixing, and cooled and taken out until the surface temperature of the foamed particles decreased to 100 ° C.
As a result of observing the surface state of the obtained expanded particles with a magnifying projector having a magnification of 10 times, expanded particles in which the powder having a melt flow rate of 5.2 g / 10 min according to the present invention was melt coated (Example 1). ), The black adhesive resin was uniformly coated over the entire particle surface, but the expanded particles (Comparative Example 1) in which the powder having a melt flow rate of 1 g / 10 min or less was melt-coated were particles It was in a state where only a few dots were attached to a part of. As a result of observing the inside of the mixer tank after taking out the foamed particles of Comparative Example 1 as a result, the bottom of the tank contains 0.1 to 0.1 grams of adhesive resin powder that was not melt-coated on the surface of the foamed particles. It was scattered as a lump of about 2 mm.
[0030]
(Production of pulverized powder of adhesive resin in which modifier is melt-kneaded)
Using an apparatus for producing resin pellets by a twin screw extruder, the adhesive resin is composed of two types of low density polyethylene (Suntech-LD, M grade, trade name; manufactured by Asahi Kasei Kogyo Co., Ltd., melting point 104, having different melt flow properties. And pellets containing 7% by weight of conductive carbon black (Ketchin Black EC-600JD, trade name; manufactured by Lion Corporation) as a modifier. The pellets were prepared and pulverized with a room temperature pulverizer to obtain a 60 mesh sieve (pass) powder.
With respect to this powder, the melt flow rate evaluated by the evaluation method described in the text was 1 g / 10 min or less in the former, and the melt flowability was extremely bad, but the latter was good at 5.2 g / 10 min. It showed fluidity.
[0031]
Next, an adhesive resin containing a modifier (conductive carbon black) in the foamed particles of the present invention (Example 1) and “known technique (Japanese Patent Publication No. 7-53381)” (shown below). It was observed using an electron microscope how the particles fixed on the surface of the expanded particles. The structural analysis results are shown in FIG. 2 (the present invention; Example 1) and FIG. 3 ("Prior Art (Japanese Patent Publication No. 7-53381)").
[0032]
According to the result of FIG. 2, the conductive carbon black in the adhesive resin is highly dispersed, and the adhesive resin containing the conductive carbon black is directly and closely fixed on the surface of the foamed particles. I understand that. The conductive carbon black of FIG. 3 is dispersed in the adhesive resin via the adhesive resin (adhesive layer) as is apparent from the manufacturing method. The dispersion state is far less dispersive and non-uniform than that of FIG. 2 melt-kneaded in an adhesive resin in advance, and the conductive carbon black is an adhesive resin (adhesive layer) above the foamed particles. You can also see that they are lurking.
The difference between the base resin of the expanded particles and the adhesive resin can be determined by the thickness of the lamella. That is, since the base resin of the expanded particles has a high melting point (= density), it can be easily determined from the lamellar thickness of the adhesive resin to 10 to 12 nm that is thicker than 8 nm.
[0033]
(Structural analysis method using electron microscope)
1) Sample pretreatment
Put the epoxy resin for embedding into gelatin capsules, harden it, fix the sample with epoxy adhesive, trim the observation part with a razor, and cool the trimming surface with a glass knife while cooling with liquid nitrogen Finish and RuO_FourVapor dyeing (1% RuO_Four(Aqueous solution) is applied overnight, then an ultrathin section of about 60 nm is prepared with an ultramicrotome (using a diamond knife), and this ultrathin section is placed on a speculum grid with a collodion film and coated with about 6 nm of carbon. A mirror sample was used.
2) Observation;
Observation was performed using a transmission electron microscope (H-500, manufactured by Hitachi, Ltd., acceleration voltage 100 kv).
[0034]
[Example 2]
In Example 1 "Preparation of ground powder of adhesive resin melt-kneaded with modifier", the adhesive resin was made of low density polyethylene (Suntech-LD, M grade, trade name; Asahi Kasei Corporation). Manufactured, melting point 104 ° C., melt flow rate 45 g / 10 min) and low molecular weight polyethylene wax (neo wax, trade name: Yasuhara Chemical Co., Ltd., melting point 109 ° C.) mixed system (low density polyethylene / low molecular weight polyethylene wax = 95/5 to 80/20), except that the melt flow rate described in the text is 3.3, 8.5, or 12 g / 10 min. As a result of producing three types of expanded particles in which the surface of the expanded particles was melt-coated, all of the obtained particles were uniformly coated with black adhesive resin over the entire surface. Part surface is exposed white was observed.
[0035]
Example 3 and Comparative Example 2
The foamed particles obtained by Example 1 and the “publicly known technology (Japanese Patent Publication No. 7-53381)” described below are accommodated in an autoclave having a pressurizing (high pressure air) and heating device, and 80 ° C. After the re-expansion treatment for increasing the internal pressure of the foamed particles by holding the pressure at 1.5 MPa (gauge pressure) for 8 hours to increase the internal pressure of the foamed particles, the pressure is adjusted to 0. Heat foaming with steam of 06MPa (gauge pressure) for 15 seconds, foaming ratio is 9cm^Three/ G secondary expanded particles. Further, in the same manner as described above, the expansion ratio was 22, 32, and 43 cm while adjusting the heating water vapor pressure in the range of 0.04 to 0.065 MPa (gauge pressure).^Three/ G of tertiary expanded particles.
The secondary and tertiary expanded particles are each filled in an in-mold mold (internal dimensions: 30 cm × 30 cm × 2.5 cmt) having water vapor holes (note) (mold open width: 8.3 to 14.7 mm) ), Heated with heated steam at a pressure of 0.11 MPa (gauge pressure), cooled and taken out from the mold, and left in a drying room at a room temperature of 80 ° C. for 12 hours (in-mold molded body, Example 3, comparison) Example 2). [(Note): Filling method in which the foamed particles are filled in the mold with the mold opened in an amount corresponding to the void volume between the foamed particles, and the mold is closed to the proper position after filling]
[0036]
About the obtained in-mold molded product (Example 3, Comparative Example 2), the conductivity and the fixing power of the modifier were evaluated by the evaluation method described in the text, and the results are shown in Table 1 and FIG.
According to the results in Table 1, it can be seen that the foamed particles of the present invention and the in-mold molded product (Example 3) are excellent in conductivity and excellent in fixing power of the modifier.
Furthermore, according to the results of FIG. 1, the expanded particles of the present invention and the molded product thereof have a very small degree of change in conductivity depending on the magnification of the molded product in the mold, and excellent conductivity is achieved even with a molded product with a high magnification. It turns out that it expresses.
It can also be seen that the foamed particles of the present invention are economically economical foamed particles that require a short modification processing time for the modifier.
[0037]
Explanation of “Known Technology (Japanese Patent Publication No. 7-53381)”
This example shows the evaluation of foamed particles in which the modifier is directly coated on the surface of the foamed particles without being melt-kneaded with the adhesive resin in advance, and in-mold molded bodies. As the modifier, fine powder was used in consideration of dispersibility during coating.
That is, a high-speed fluid mixer (Supermixer SMV-500, trade name: manufactured by Kawata Co., Ltd., rotation speed: inverter-controlled continuous transmission 100-900 rpm, temperature detection end: J-type φ1 mm attached to the lower part of the guide plate, jacket: 30 Cross-linked polyethylene foam particles (Mef LD, trade name: manufactured by Asahi Kasei Kogyo Co., Ltd., melting point: 117 ° C., magnification: 4 cm)^Three/ G) is 0.4 m in bulk volume^ThreeThe mixing is continued until the surface temperature of the foamed particles reaches 110 ° C. due to the fluid frictional heat between the mixing blade and the foamed particles rotating at a high speed and the rotational speed of 900 rpm. As a pulverized powder of adhesive resin, low density polyethylene (Suntech-LD, M grade, trade name: manufactured by Asahi Kasei Kogyo Co., Ltd., melting point 104 ° C., melt flow rate 55 g / 10 min, 60 mesh sieve pass product) Half of the amount of 2.79% by weight with respect to the weight of the expanded particles was supplied little by little over 1 minute, mixed for 4 minutes from the start of supply, and the surface of the expanded particles was melt-coated with the adhesive resin. Thereafter, conductive carbon black (Ketchin Black ECP-600JD, trade name; manufactured by Lion Corporation * finely pulverized product used in Example 1 and Comparative Example 1) as a modifier is added to the total weight of the adhesive resin. In contrast, 7.53% by weight is supplied little by little over 0.5 minutes, mixed for 1.5 minutes from the start of supply, and entangled with the adhesive resin on the surface of the particles. The functional resin was supplied little by little over 1 minute and mixed for 8 minutes from the start of supply.
During mixing, the temperature of the foamed particles was controlled from the air outlet provided in the lid of the mixer main body so that the surface temperature of the foamed particles did not exceed 110 ° C.
[0038]
Thereafter, the number of revolutions was reduced to 200 rpm, and continuously blown from the lid air outlet under intermittent mixing, and cooled and taken out until the surface temperature of the foamed particles decreased to 100 ° C.
As a result of observing the surface state of the obtained foamed particles with a magnifying projector having a magnification of 10 times as in Example 1, it was observed that the modifier was uniformly coated over the entire particle surface. .
[0039]
[Example 4]
The “preparation of pulverized powder of adhesive resin in which a modifier is melt-kneaded” in Example 1 is shown below, and the coating supply amount to the foamed particles is 7% by weight with respect to the weight of the foamed particles. In the same manner as in Example 1, foamed particles obtained by melt-coating the pulverized powder of an adhesive resin obtained by melt-kneading a surfactant-type antistatic agent on the surface of the foamed particles were obtained.
As a result of observing the surface state of the obtained expanded particles with a magnifying projector having a magnification of 10 times, the red adhesive resin was uniformly coated over the entire particle surface.
According to Example 3, the expanded particles had an expansion ratio of 32 cm.^Three/ G tertiary foamed particles, followed by in-mold molding and a magnification of 30 cm^Three/ G in-mold molded product.
[0040]
As a result of evaluating the antistatic property of the obtained in-mold product by the evaluation method described in the text, the surface resistivity was 2.6 × 10.¹¹It had excellent antistatic property of Ω. Moreover, although it evaluated also about friction resistance and peeling resistance, it was excellent in practicality.
(Production of pulverized powder of adhesive resin in which modifier is melt-kneaded)
Using a resin pellet manufacturing apparatus with a single screw extruder, the adhesive resin is low density polyethylene (Suntech-LD, M grade, trade name; manufactured by Asahi Kasei Kogyo Co., Ltd., melting point 104 ° C., melt flow rate 55 g / 10 min. And pellets containing 5% by weight of a surfactant-type antistatic agent (Denon 2220, trade name; manufactured by Maruhishi Oil Chemical Co., Ltd., HLB 4.6) as a modifier. In addition, a red pigment (Cromophthal Scarlet R 0.06% by weight) was simultaneously added as a colorant. The pellets were pulverized with a room temperature pulverizer to obtain a 40 mesh sieve (pass) powder. With respect to this powder, the melt flow rate evaluated by the evaluation method described in the text showed good fluidity at 53 g / 10 min.
As reference,
[0041]
[Comparative Example 3]
Using a tumbler-type blender, a red pigment (chromofal scarlet R 0.06% by weight) was added to and mixed with the pulverized powder of the adhesive resin of the above-mentioned “known technique (Japanese Patent Publication No. 7-53381)”. Of the foamed particles was used in an amount of 6.65% by weight, the modifier was the surfactant type antistatic agent of Example 4, and the amount supplied was 5. 5% of the total weight of the adhesive resin. As a result of carrying out in the same manner as in “Known art (Japanese Patent Publication No. 7-53381)” except that the amount was 26% by weight, most of the surfactant type antistatic agent as a modifier was a tank wall of the mixer. Thus, it was impossible to obtain foamed particles in which the surface of the foamed particles was preferentially melt-coated with a surfactant-type antistatic agent.
[0042]
[Example 5]
In Example 1 "Preparation of ground powder of adhesive resin melt-kneaded with modifier", the adhesive resin was made of low density polyethylene (Suntech-LD, M grade, trade name; Asahi Kasei Corporation). The melting point is 104 ° C., the melt flow rate is 45 g / 10 min), and a polymer type permanent antistatic agent (ROLEX AS-170, trade name: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is used as a modifier for this polyethylene. A powder having a melt flow rate of 80 g / 10 min evaluated by the evaluation method described in the text was obtained in the same manner as in Example 1 except that pellets containing 30% by weight were used. In addition, a red pigment (Cromophthal Scarlet R 0.06% by weight) was simultaneously added as a colorant.
Using this powder, in the same manner as in Example 1, expanded particles in which an adhesive resin containing a polymer type permanent antistatic agent as a modifier was fixed on the surface of the expanded particles were used. However, the supply amount of the pulverized powder of the adhesive resin was 8% by weight with respect to the weight of the expanded particles.
[0043]
Thereafter, the foamed particles were filled in an in-mold molding die having water vapor holes in the same manner as in Example 3 to obtain an in-mold molded body.
The obtained in-mold molded product has a magnification of 4 cm.^ThreeWhen the antistatic property is evaluated by the method described in the text, the surface resistivity is 6.2 × 10^TenIt had a high level of antistatic performance of Ω. The evaluation of the fixing power of the modifier was also excellent in practicality.
The function of the molded body in the mold is for the purpose of sustaining the antistatic property. As an example of the evaluation, deterioration of the antistatic property due to repeated water washing was evaluated. That is, a soft urethane sponge (bulk density: 0.025 g / cm) in a 0.15% by volume aqueous solution of a kitchen detergent (Mama Royal, trade name; manufactured by Lion Corporation).^ThreeThe surface of the molded body was washed 20 times with water and washed with water, and then dried in a 25 ° C. air circulation thermostat, and the antistatic property was evaluated by the evaluation method described in the text. As a result, this operation was repeated 20 times. Even after that, the same surface resistivity as that before cleaning was maintained.
[0044]
As a reference example, the diameter of the above-mentioned polymer type permanent antistatic agent was added to a low-density polyethylene (Suntech LD, trade name; manufactured by Asahi Kasei Kogyo Co., Ltd., melting point 117 ° C.) as a reference example. An extruded granulated mini-pellet with a length of 0.9 mm and a length of 1.2 mm was prepared, and this mini-pellet was impregnated with dicumyl peroxide (crosslinking agent) in a water suspension system and subjected to a crosslinking reaction at 160 ° C. for 45 minutes. Thus, crosslinked polyethylene resin particles were obtained. After impregnating the particles with butane gas by a known method, the expansion ratio is 4 cm using a foaming apparatus.^Three/ G of cross-linked polyethylene foam particles was obtained, but the cell structure was uneven and the expansion ratio was 2 cm.^Three/ G or less fine foamed particles were obtained, and foam expansion ability could not be expected.
[0045]
[Table 3]

[0046]
【The invention's effect】
According to the present invention, a polyolefin-based resin expanded particle having various functions such as conductivity, antistatic property, and flame retardancy can be easily added in one step without requiring a high-level and highly skilled technique. It is possible to obtain functional polyolefin resin expanded particles fixed on the surface of the resin, and to use this, it is possible to provide an in-mold molded product having an excellent function more economically, which can exhibit a particularly remarkable effect. .
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the expansion ratio and electrical conductivity of an in-mold molded product molded according to the present invention (Example 3) and Comparative Example 2 (“Prior Art (Japanese Patent Publication No. 7-53381)”). is there.
FIG. 2 is a conceptual diagram showing the surface state of expanded particles that are melt-coated with an adhesive resin containing a modifier (conductive carbon black) molded according to the present invention (Example 1).
FIG. 3 is a conceptual diagram showing the surface state of expanded particles melt-coated with an adhesive resin containing a modifier (conductive carbon black) molded by “known technology (Japanese Patent Publication No. 7-53381)”. is there.
[Explanation of symbols]
1, 1 ': Conductive carbon black
2, 2 ': Adhesive resin
2 ": Adhesive resin (adhesive layer)
3, 3 ': Polyethylene foam particles (skin part)

Claims

A method for producing a functional polyolefin resin foam particle in which an adhesive resin containing a modifier is fixed on the surface of a polyolefin resin foam particle, and using a high-speed flow mixer, the surface of the polyolefin resin foam particle is The melting point of the adhesive resin obtained by melt-kneading a modifier having a melting flowability of -30 ° C. to -3 ° C. of the above-mentioned expanded particle melting point and a melt flow rate of 3 to 80 g / 10 min. method of manufacturing to that feature of the polyolefin resin expanded particles, characterized in that 1 to 15 wt% melt coating relative to the weight of the pulverized powder above expanded beads.

The method for producing functional polyolefin-based resin expanded particles according to claim 1, wherein the pulverized powder of the adhesive resin has a particle size of 10 to 145 mesh sieve (pass).

The functional polyolefin system according to claim 1 or 2, wherein the modifier is a conductive carbon black, and the concentration of the modifier is 3 to 15% by weight based on the weight of the adhesive resin. A method for producing resin foam particles.

The modifying agent is a surfactant-type antistatic agent having an HLB of 2 to 10, and the addition concentration thereof is 0.5 to 10% by weight based on the weight of the adhesive resin. The manufacturing method of the functional polyolefin resin expanded particle of Claim 1 or Claim 2.

The said modifier is a polymer-type permanent antistatic agent of polyolefin resin, The addition density | concentration is 7 to 50 weight% with respect to the weight of adhesive resin, The claim 1 or Claim characterized by the above-mentioned. Item 3. A process for producing a functional polyolefin resin expanded particle according to Item 2.