JP4912567B2 - Recycled expandable styrene resin particles, expanded beads and expanded molded products - Google Patents

Abstract

A process for producing expandable reclaimed-styrene resin particles 10 which comprises suspending particles of a reclaimed styrene resin as nuclei in an aqueous medium, adding a polymerization initiator to this suspension to infiltrate the initiator into the reclaimed-styrene resin particles, subsequently adding a styrene monomer to conduct polymerization, and then infiltrating a blowing agent into the particles. It is possible to dissolve the polymerization initiator in a styrene monomer and infiltrate this initiator into the reclaimed-styrene resin particles. The polymerization reaction can be conducted while the oxygen concentration in the reaction tank is kept low in at least a later part of the polymerization, whereby the surface 1 can have a high weight-average molecular weight.

Description

【００４５】
［再生発泡性スチレン系樹脂粒子の製造における重合開始剤の影響］
参考例８
（核の製造）
発泡スチレン系樹脂成形品（日立化成工業（株）製ハイビーズＳＳＢ−ＨＸより得られた成型品）を２２０℃の熱風で収縮させ、見かけ比重０．８、大きさ５００ｍｍ×４００ｍｍ×１００ｍｍ及び重さ約１６ｋｇの収縮物を得た。この収縮物を１０ｍｍのスクリーンをとりつけた粉砕機（ＺＡ−５６０型粉砕機、株式会社ホーライ商品名）で粗粉砕した。このとき得られた粗粉砕物の最大長さは、おおよそ１０ｍｍ、かさ比重０．６５であった。次いで、ヘンシェルミキサー（三井三池化工製、ＦＭ１０Ｂ）にこの粗粉砕物２０００ｇ及び平均粒子径が１０μｍのタルク（林化成製、ミクロホワイト＃５０００）２０ｇ及びエチレンビスステアリルアミド０．６ｇを入れ、２０００ｒｐｍで２分間混合した。このタルク及びエチレンビスステアリルアミドで被覆された粗粉砕物をベント付き３０ｍｍ押出機（Ｔ型ダイス、シート幅３００ｍｍ、シート肉圧１ｍｍ）を用いて押出速度とほぼ同じ速度でシートを引きながら溶融押出した。さらに冷却固化前に、押出方向に対し水平に、１ｍｍ間隔、深さ０．５ｍｍのスリットをロールで設け、冷却固化後、切断機で約１０〜１５ｃｍに切断した。引き続き、得られたシート状スチレン系樹脂の切断片を、２ｍｍのスクリーンをとりつけた粉砕機（ＶＭ−１６型粉砕機、株式会社オリエント商品名）で細粉砕した。細粉砕物を、０．６〜１．２ｍｍの範囲に篩で分級し再生スチレン系樹脂粒子とした。
この再生スチレン系樹脂粒子の重量平均分子量は１６．９万、比重は０．９１であった。
（再生発泡性粒子の製造）
５リットルの耐圧撹拌容器に脱イオン水１９００ｇ、上記の再生スチレン系樹脂粒子１１００ｇ、リン酸三カルシウム１２．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０９ｇを仕込み、撹拌しながら７５℃に昇温した。
次いで、単量体分散容器に脱イオン水４００ｇとポリビニルアルコール１．３ｇを入れ混合し、これにｔ−ブチルパーオキサイド０．２ｇ、ベンゾイルパーオキサイド２．９ｇを溶解したスチレン単量体２００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に添加し、６０分保温したのち、９０℃に昇温した。次いで、スチレン単量体９００ｇを連続的に５時間かけて等速度（３．０ｇ／分）で添加した。
次いで、リン酸三カルシウム２．２ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。次いで、１００℃まで冷却し、発泡剤としてブタン（ｉ／ｎ比＝４／６、重量比以下同じ）１８０ｇを２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸された再生発泡性スチレン系樹脂粒子を取り出し、脱水乾燥した。この樹脂粒子の平均分子量は２７．０万であった。
次いで、この樹脂粒子を目開き０．６ｍｍ〜１．７ｍｍの篩で分級し、得られた樹脂粒子に対しステアリン酸亜鉛０．１重量％、硬化ひまし油０．１重量％を加え表面被覆し再生発泡性スチレン系樹脂粒子を得た。
得られた再生発泡性スチレン系樹脂粒子を、５０ｍｌ／ｇに予備発泡し、約１８時間熟成後、ダイセン工業製発泡スチレン系樹脂成型機ＶＳ−３００を用い、成形圧力０．０８ＭＰａで成形し、成形品を得た。
【００４６】
参考例９
参考例８において、ベンゾイルパーオキサイドを２．３ｇとした以外は、参考例８と同様に行い、再生発泡性スチレン系樹脂粒子を得た。このとき、得られた再生発泡性スチレン系樹脂粒子の重量平均分子量は３２．２万であった。
【００４７】
参考例１０
参考例８において、ベンゾイルパーオキサイドを１．６５ｇとした以外は、参考例８と同様に行い、再生発泡性スチレン系樹脂粒子を得た。このとき、得られた再生発泡性スチレン系樹脂粒子の重量平均分子量は４３．３万であった。
【００４８】
評価例２
参考例８〜参考例１０において、表層部の重量平均分子量は以下のように測定した。
発泡性スチレン系樹脂粒子の分子量は粒子を発泡させて測定した。５０ｍｌ／ｇに発泡した樹脂粒子の一部を用いて、顕微鏡で観察しながら、剃刀で、第１図に示すように、粒子１０を９等分した。最も表面側にある表層部Ｓの重量平均分子量を測定した。
分子量は、以下の条件でＨＰＬＣ測定した。
カラム：ＧＬ−Ｒ４００Ｍ（φ１０．７×３００ｍｍ）２本
カラム温度：室温
溶離液：ＴＨＦ
流 量：２．０ｍＬ／ｍｉｎ
検出器：ＵＶ ２２０ｎｍ
注入量：１００μＬ
参考例８〜参考例１０の評価結果を表２に示す。
【００４９】
【表２】

【００５０】
［再生発泡性スチレン系樹脂粒子の製造における酸素濃度の影響］
実施例１
（核の製造）
参考例１と同様にして、重量平均分子量が２０．０万の再生スチレン系樹脂を得た。
（再生発泡性粒子の製造）
５リットルの耐圧撹拌容器に脱イオン水１７００ｇ、上記の再生スチレン系樹脂粒子（核）１０００ｇ、リン酸三カルシウム１０．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０８ｇを仕込み、撹拌し７０℃まで昇温した。
次いで、単量体分散容器に脱イオン水３００ｇとポリビニルアルコール０．３６ｇを入れ混合し、これにベンゾイルパーオキサイド２．７０ｇ、ｔ−ブチルパーオキシイソプロピルモノカーボネート０．２０ｇを溶解したスチレン単量体３００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に３０分かけて添加し、その後３０分保温したのち、９０℃まで昇温した。
その後、スチレン単量体７００ｇを連続的に３時間かけて等速度で添加した。この際、耐圧撹拌容器内を窒素パージし酸素濃度を２〜５体積％に保った。３時間後の、重合率は８５％であった。
次いで、リン酸三カルシウム２．４ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。この間も上記酸素濃度に保った。２時間後の重合率は９８％以上であった。その後、１００℃まで冷却し発泡剤としてブタン（ｉ／ｎ比＝４／６）を１００ｇづつ２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸されたスチレン系樹脂粒子を取り出し、脱水乾燥した。
次いで、この重合体粒子を目開き１．７ｍｍの篩で分級し、篩を通過した重合体粒子をさらに目開き０．６ｍｍの篩で分級し、篩上に残った樹脂粒子に対しステアリン酸亜鉛０．１重量％、硬化ひまし油０．１重量％を加え表面被覆し再生発泡性スチレン系樹脂粒子を得た。
得られた再生発泡性スチレン系樹脂粒子を、５０ｍｌ／ｇに発泡し、約１８時間熟成後、ダイセン工業製発泡スチレン系樹脂成形機ＶＳ−３００を用い、成形圧力０．０８ＭＰａで成形し、成形品を得た。
実施例において、重合率は、合成中の樹脂粒子を採取し、以下の装置及び条件にて測定した。
測定装置：（株）日立製作所社製
溶離液：アセトニトリル／蒸留水＝７０／３０、流量：１ｍｌ／分
検出器：ＵＶ ２３０ｎｍ
カラム：Ｉｎｅｒｔｓｉｌ ＯＤＳ−２
【００５１】
実施例２
（再生発泡性粒子の製造）
５リットルの耐圧撹拌容器に脱イオン水１７００ｇ、実施例１と同じ方法で作製した再生スチレン系樹脂粒子（核）１０００ｇ、リン酸三カルシウム１０．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０８ｇを仕込み、撹拌し７０℃まで昇温した。
次いで、単量体分散容器に脱イオン水３００ｇとポリビニルアルコール０．３６ｇを入れ混合し、これにベンゾイルパーオキサイド２．７０ｇ、ｔ−ブチルパーオキシイソプロピルモノカーボネート０．２０ｇを溶解したスチレン単量体３００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に３０分かけて添加し、その後３０分保温したのち、９０℃まで昇温した。
その後、スチレン単量体７００ｇを連続的に３時間かけて等速度で添加した。この際、耐圧撹拌容器内を窒素パージし酸素濃度を０．５体積％以下に保った。３時間後の重合率は９３％であった。
次いで、リン酸三カルシウム２．４ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。この間も上記酸素濃度に保った。２時間後の重合率は９８％以上であった。その後、１００℃まで冷却し発泡剤としてブタン（ｉ／ｎ比＝４／６）を１００ｇづつ２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸されたスチレン系樹脂粒子を取り出し、脱水乾燥した。その後、実施例１と同様の方法で分級、添加剤で表面被覆、発泡、成形した。
【００５２】
実施例３
（再生発泡性粒子の製造）
実施例２において、最初から窒素パージして反応槽内の酸素濃度を１体積％以下に保った他は、実施例２と同様にして製造した。
【００５３】
比較例１
（再生発泡性粒子の製造）
比較として、酸素濃度を低下させずに再生発泡性スチレン系樹脂粒子を製造した。
５リットルの耐圧撹拌容器に脱イオン水１７００ｇ、参考例１と同じ方法で作製した再生発泡性スチレン系樹脂粒子１０００ｇ、リン酸三カルシウム１０．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０８ｇを仕込み、撹拌し７０℃まで昇温した。
次いで、単量体分散容器に脱イオン水３００ｇとポリビニルアルコール０．３６ｇを入れ混合し、これにベンゾイルパーオキサイド２．７０ｇ、ｔ−ブチルパーオキシイソプロピルモノカーボネート０．２０ｇを溶解したスチレン単量体３００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に３０分かけて添加し、その後３０分保温したのち、９０℃まで昇温した。
その後、スチレン単量体７００ｇを連続的に３時間かけて等速度で添加した。この際、耐圧撹拌容器内を窒素パージせず重合を進めたところ、酸素濃度は１７〜２０体積％であった。このときの、重合率は８５％であった。
次いで、リン酸三カルシウム２．４ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。その後、１００℃まで冷却し発泡剤としてブタン（ｉ／ｎ比＝４／６）を１００ｇづつ２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸されたスチレン系樹脂粒子を取り出し、脱水乾燥した。その後、実施例１と同様の方法で分級、添加剤で表面被覆、発泡、成形した。
【００５４】
実施例４
（核の製造）
参考例８と同様にして、重量平均分子量が１６．９万、比重が０．９１の再生スチレン系樹脂粒子を得た。
（再生発泡性粒子の製造）
５リットルの耐圧撹拌容器に脱イオン水１９００ｇ、上記の再生スチレン系樹脂粒子（核）１１００ｇ、リン酸三カルシウム１２．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０９ｇを仕込み、撹拌しながら７５℃に昇温した。
次いで、単量体分散容器に脱イオン水４００ｇとポリビニルアルコール１．３ｇを入れ混合し、これにｔ−ブチルパーオキサイド０．２ｇ、ベンゾイルパーオキサイド２．９ｇを溶解したスチレン単量体２００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に３０分かけて添加し、その後６０分保温したのち、９０℃に昇温した。
その後、スチレン単量体９００ｇを連続的に５時間かけて等速度（３．０ｇ／分）で添加した。この際、耐圧攪拌容器内を窒素パージし酸素濃度を２〜５体積％に保った。このときのスチレン単量体含有率は１５％（重合率８５％）であった。
次いで、リン酸三カルシウム２．２ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。次いで、１００℃まで冷却し、発泡剤としてブタン（ｉ／ｎ比＝４／６、重量比以下同じ）１８０ｇを２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸された再生発泡性スチレン系樹脂粒子を取り出し、脱水乾燥した。その後、実施例１と同様の方法で分級、表面被覆、予備発泡、成形した。
【００５５】
実施例５
（再生発泡性粒子の製造）
５リットルの耐圧撹拌容器に脱イオン水１９００ｇ、実施例４で製造した再生スチレン系樹脂粒子（核）１１００ｇ、リン酸三カルシウム１２．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０９ｇを仕込んだ。次いで、耐圧攪拌容器内を窒素パージし、酸素濃度を２〜５体積％とした。その後攪拌しながら７５℃に昇温した。
次いで、単量体分散容器に脱イオン水４００ｇとポリビニルアルコール１．３ｇを入れ混合し、これにｔ−ブチルパーオキサイド０．２ｇ、ベンゾイルパーオキサイド２．９ｇを溶解したスチレン単量体２００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に３０分かけて添加し、その後６０分保温したのち、９０℃に昇温した。
その後、スチレン単量体９００ｇを連続的に５時間かけて等速度（３．０ｇ／分）で添加した。この際、耐圧攪拌容器内を窒素パージし酸素濃度を２〜５体積％に保った。このときのスチレン単量体含有率は１３％（重合率８７％）であった。
次いで、リン酸三カルシウム２．２ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。次いで、１００℃まで冷却し、発泡剤としてブタン（ｉ／ｎ比＝４／６、重量比以下同じ）１８０ｇを２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸された再生発泡性スチレン系樹脂粒子を取り出し、脱水乾燥した。その後、実施例１と同様の方法で分級、添加剤で表面被覆、発泡、成形した。
【００５６】
実施例６
（再生発泡性粒子の製造）
５リットルの耐圧撹拌容器に脱イオン水１９００ｇ、実施例４で製造した再生スチレン系樹脂粒子（核）１１００ｇ、リン酸三カルシウム１２．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０９ｇを仕込んだ。次いで、耐圧攪拌容器内を窒素パージし、酸素濃度を０．５〜１体積％とした。その後攪拌しながら７５℃に昇温した。
次いで、単量体分散容器に脱イオン水４００ｇとポリビニルアルコール１．３ｇを入れ混合し、これにｔ−ブチルパーオキサイド０．２ｇ、ベンゾイルパーオキサイド２．９ｇを溶解したスチレン単量体２００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒撹拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に３０分かけて添加し、その後６０分保温したのち、９０℃に昇温した。
その後、スチレン単量体９００ｇを連続的に５時間かけて等速度（３．０ｇ／分）で添加した。この際、耐圧攪拌容器内を窒素パージし酸素濃度を０．５〜１体積％に保った。このときのスチレン単量体含有率は１０％（重合率９０％）であった。
次いで、リン酸三カルシウム２．２ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。次いで、１００℃まで冷却し、発泡剤としてブタン（ｉ／ｎ比＝４／６、重量比以下同じ）１８０ｇを２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸された再生発泡性スチレン系樹脂粒子を取り出し、脱水乾燥した。その後、実施例１と同様の方法で分級、添加剤で表面被覆、発泡、成形した。
【００５７】
比較例２
比較として、実施例４において、耐圧攪拌容器内の窒素パージを行わない以外は、実施例４と同様に行い、再生発泡性スチレン系樹脂粒子を得た。このときの酸素濃度は１７〜２０体積％であった。
【００５８】
評価例３
実施例１〜実施例６、比較例１，２において、表面部分及び中心部分の重量平均分子量は以下のように測定した。
再生発泡性スチレン系樹脂粒子を飽和水蒸気中で嵩倍数５０ｍｌ／ｇに発泡した。
任意の発泡粒子２〜３粒を採取し、剃刀で第２図に示すように粒子１を半分等間隔に５等分して、外側から、部分１，２，３，４，５を形成した。最も表面側の部分１（表面部分）についてはそのまま、最も内側の部分５（中心部分）についてはこの部分を５等分した中心を注射針で繰り抜いて取り出し、分子量を測定した。部分３（中心より３／５部分）については部分５と同じ中心を注射針で繰り抜いて取り出し、分子量を測定した。
尚、融着率は、成形品を割った際の破断面における、破断したビーズと破断していないビーズの割合で示した。
融着率（％）
＝破断したビーズ数／（破断したビーズ数＋破断していないビーズ数）
実施例１〜実施例６、比較例１，２の評価結果を表３に示す。
【００５９】
【表３】

【００６０】
さらに、実施例６及び比較例２で得た再生発泡性スチレン系樹脂粒子の表面部分について、ゲルパーミエーションクロマトグラフ（ＧＰＣ）法によるチャート（ＧＰＣチャート）を得た。そのとき、以下の装置及び条件で測定した。
測定装置：（株）日立製作所製
溶離液：ＴＨＦ、 流量：２ｍｌ／分
検出器：ＵＶ ２２０ｎｍ
カラム：日立化成工業（株）社製 ＧＬ−Ｒ４００Ｍ ２本
実施例６及び比較例２のＧＰＣチャートを、それぞれ、第３図（ａ），（ｂ）に示す。これらの図に示されるように、実施例６のように急に分子量が高くなる粒子は、ＧＰＣチャートが二山を有していた。二山は高分子ポリマー比率が多いため形成される。一方、比較例２のように分子量が少しずつ上がる粒子は、ＧＰＣチャートに若干の膨らみが見られるものの、変曲点が無くショルダーも二山も形成していなかった。
【００６１】
［核への無機物及び／又は有機系滑剤添加の影響］
参考例１１
（核の製造）
発泡スチレン系樹脂成形品（日立化成工業（株）製ハイビーズＳＳＢ−ＨＸより得られた成形品）を２２０℃の熱風で収縮させ、見かけ比重０．７５、大きさ５００ｍｍ×４００ｍｍ×１００ｍｍ及び重さ１５ｋｇの収縮物を得た。この収縮物を１０ｍｍのスクリーンを取り付けた粉砕機（株式会社ホーライ製、ＺＡ−５６０型粉砕機）で粗粉砕した。このとき得られた粗粉砕物の最大長さは、おおよそ１０ｍｍ、かさ比重０．５であった。
次いで、ヘンシェルミキサー（三井三池化工製、ＦＭ１０Ｂ）にこの粗粉砕物２０００ｇ及び平均粒子径が１０μｍのタルク（林化成株式会社製、ホワイトミクロン＃５０００）２０ｇ及びエチレンビスステアリルアミド０．６ｇを入れ、２０００ｒｐｍで２分間混合した。このタルク及びエチレンビスステアリルアミドで表面被覆された粗粉砕物をベント付き３０ｍｍ押出機（Ｔ型ダイス、シート幅３００ｍｍ、シート肉圧１ｍｍ）を用いて押出速度とほぼ同じ速度でシートを引きながら溶融押出した。
さらに、冷却固化前に、押出方向に対し水平に、１ｍｍ間隔、深さ０．５ｍｍのスリットをロールで設け、冷却固化後、切断機で約１０〜１５ｃｍに切断した。引き続き、得られたシート状スチレン系樹脂の切断片を、２ｍｍのスクリーンを取り付けた粉砕機（ＶＭ−１６型粉砕機、株式会社オリエント商品名）で細粉砕した。細粉砕物を、０．６〜１．０ｍｍの範囲に篩で分級し再生スチレン系樹脂粒子とした。
（再生発泡性粒子の製造）
５リットルの耐圧攪拌容器に上記の再生スチレン系樹脂粒子１１００ｇ、脱イオン水１５００ｇ、リン酸三カルシウム１２．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０９ｇを仕込み、攪拌しながら７０℃に昇温した。
次いで、単量体分散容器に脱イオン水３５０ｇとポリビニルアルコール０．３６ｇを入れ混合し、これにｔ−ブチルパーオキサイド３．２ｇを溶解したスチレン単量体２００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒攪拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に添加し、９０分保温したのち、９０℃に昇温した。次いで、スチレン単量体６００ｇを連続的に３時間かけて等速度（３．３ｇ／分）で添加した。
次いで、リン酸三カルシウム２．４ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、２時間保温した。次いで、１００℃まで冷却し、発泡剤としてブタン（イソブタン／ｎ−ブタンの重量比＝４／６）を１６０ｇづつ２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。
室温まで冷却した後、発泡剤が含浸された発泡性スチレン系樹脂粒子を取り出し、脱水乾燥した。次いで、この樹脂粒子を目開き１．７０ｍｍ及び０．６０ｍｍの篩で分級し、２２４０ｇの樹脂粒子を得た。得られた樹脂粒子にステアリン酸亜鉛１．１２ｇ、次いで、硬化ひまし油２．２４ｇを順次加えて混合した。
次いで、この樹脂粒子を目開き１．７０ｍｍ及び０．６０ｍｍの篩で分級し、２２４０ｇの樹脂粒子を得た。得られた樹脂粒子に、ステアリン酸亜鉛１．１２ｇ、次いで、硬化ひまし油２．２４ｇを順次加えて混合し、再生発泡性スチレン系樹脂粒子を得た。
得られた再生発泡性スチレン系樹脂粒子を、５０ｍｌ／ｇに予備発泡し、約１８時間熟成した後、発泡スチレン系樹脂用成型機（ダイセン工業製 ＶＳ−３００）を用い、成形圧力０．０８ＭＰａで成形し、成形品を得た。
【００６２】
参考例１２
参考例１１において、タルクを４０ｇ、エチレンビスステアリルアミドを使用しない以外は、参考例１１と同様な操作を行い、再生発泡性スチレン系樹脂粒子及び成形品を得た。
【００６３】
参考例１３
参考例１１において、エチレンビスステアリルアミドを１．０ｇ、タルクを使用しない以外は、参考例１１と同様な操作を行い、再生発泡性スチレン系樹脂粒子及び成形品を得た。
【００６４】
参考例１４
参考例１１において、タルクを平均粒子径が１２μｍの炭酸カルシウムとした以外は、参考例１１と同様な操作を行い、再生発泡性スチレン系樹脂粒子及び成形品を得た。
【００６５】
参考例１５
比較として、参考例１１において、タルク及びエチレンビスステアリルアミドを使用しない以外は、参考例１１と同様の操作を行い、再生発泡性スチレン系樹脂粒子及び成形品を得た。
【００６６】
評価例４
参考例１１〜参考例１５において、セル径は、発泡粒子を鋭利なカッターナイフ等で切り取り、その断面の顕微鏡写真を撮影し、得られた写真よりセル１０個の径を測定し、その平均をセル径とした。
参考例１１〜参考例１５の評価結果を表４に示す。
【００６７】
【表４】

【００６８】
［核（再生スチレン系樹脂粒子）の粒子径の影響］
参考例１６
（核の製造）
参考例１と同様の方法で、細粉砕物を得た。この細粉砕物を、目開き１．４０ｍｍ及び０．８５ｍｍの篩を用いて分級し、再生スチレン系樹脂粒子とした。得られた再生スチレン系樹脂粒子の平均粒子径は１１７０μｍであり、３００μｍ以下の粒子の含有量は０．４重量％であった。
（再生発泡性粒子の製造）
５リットルの耐圧攪拌容器に上記の再生スチレン系樹脂粒子１１００ｇ、脱イオン水１５００ｇ、リン酸三カルシウム１２．０ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０９ｇを仕込み、攪拌しながら７０℃に昇温した。
次いで、単量体分散容器に脱イオン水３５０ｇとポリビニルアルコール０．３６ｇを入れて混合し、これにｔ−ブチルパーオキシ−２−エチルヘキシルカーボネート０．２５ｇを溶解したスチレン単量体３００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒間攪拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に添加し、その後３０分間保温した。
次いで、単量体分散容器に脱イオン水３００ｇ、ポリビニルアルコール０．２４ｇを入れて混合し、これにベンゾイルパーオキサイド３．０ｇを溶解したスチレン単量体２００ｇを加え、ホモミキサー（特殊機化工業製）を用いて５８００ｒｐｍで１２０秒間攪拌しスチレン単量体を微細（単量体油滴の平均径１０〜１００μｍ）に分散させた。このスチレン単量体分散液を容器内に添加し、９０分保温した後、９０℃に昇温した。
その後、スチレン単量体６００ｇを連続的に３時間かけて等速度（３．３ｇ／分）で添加した。
次いで、リン酸三カルシウム２．４ｇ、ドデシルベンゼンスルホン酸ナトリウム０．０５ｇを添加した後、１１５℃に昇温し、５時間保温した。その後、１００℃まで冷却し、発泡剤としてブタン（ｉ／ｎ比＝４／６、重量比、以下同じ。）を８０ｇづつ２回に分けて圧入し、１０時間保持して発泡剤の含浸を行った。室温まで冷却した後、発泡剤が含浸されたスチレン系樹脂粒子を取り出し、脱水乾燥した。
次いで、この樹脂粒子を目開き２．００ｍｍ及び０．８５ｍｍの篩で分級し、２２１０ｇの樹脂粒子を得た。得られた樹脂粒子に対し、ステアリン酸亜鉛１．１１ｇ、次いで、硬化ひまし油１．１１ｇを順次加えて混合し、再生発泡性スチレン系樹脂粒子を得た。
得られた再生発泡性スチレン系樹脂粒子を、５０ｍｌ／ｇに予備発泡し、約１８時間熟成した後、発泡スチレン系樹脂用成型機（ダイセン工業製 ＶＳ−３００）を用い、成形圧力０．０８ＭＰａで成形し、成形品を得た。
【００６９】
参考例１７
（核の製造）
参考例１６と同様の方法でスチレン系樹脂の細粉砕物を作製し、目開き１．７０ｍｍ及び０．６０ｍｍの篩を用いて分級し、再生スチレン系樹脂粒子とした。得られた再生スチレン系樹脂粒子の平均粒子径は１２６０μｍであり、３００μｍ以下の粒子の含有量は０．６重量％であった。
（再生発泡性粒子の製造）
上記の再生スチレン系樹脂粒子を用いて参考例１６と同様の操作を行い、得られた樹脂粒子を目開き２．２０ｍｍ及び０．６０ｍｍの篩で分級して２１６０ｇの樹脂粒子を得た。得られた樹脂粒子に対し、ステアリン酸亜鉛１．８０ｇ、次いで、硬化ひまし油１．０８ｇを順次加えて混合し、再生発泡性スチレン系樹脂粒子を得た。
得られた再生発泡性スチレン系樹脂粒子を用いて、参考例１６と同様に予備発泡及び成形を行い、成形品を得た。
【００７０】
参考例１８
（核の製造）
参考例１６と同様の方法でスチレン系樹脂の細粉砕物を作製し、目開き１．４０ｍｍ及び０．４３ｍｍの篩を用いて分級し、再生スチレン系樹脂粒子とした。得られた再生スチレン系樹脂粒子の平均粒子径は１０６０μｍであり、３００μｍ以下の粒子の含有量は２．４重量％であった。
（再生発泡性粒子の製造）
上記の再生スチレン系樹脂粒子を用いて参考例１６と同様の操作を行い、得られた樹脂粒子を目開き１．７０ｍｍ及び０．５０ｍｍの篩で分級して２１１０ｇの樹脂粒子を得た。得られた樹脂粒子に対し、ステアリン酸亜鉛１．６０ｇ、次いで、硬化ひまし油１．０６ｇを順次加えて混合し、再生発泡性スチレン系樹脂粒子を得た。
得られた再生発泡性スチレン系樹脂粒子を用いて、参考例１６と同様に予備発泡及び成形を行い、成形品を得た。
【００７１】
評価例５
参考例１６〜参考例１８において、平均粒子径は以下のように測定した。
（１）ＪＩＳ標準篩（ＪＩＳ Ｚ ８８０１）を以下に示した目開き（単位：ｍｍ）の順に重ねて配列した（ただし、最下段には皿を加えて配置する）。
上段から順に２．００、１．７０、１．４０、１．１８、１．００、０．８５、０．７１、０．６０、０．５０、０．４２５、０．３５５、０．３０、０．２５
（２）試料１００ｇを計量し、篩の最上段に入れた。
（３）最上段から順に、篩から試料が落下しなくなるまでふるった。篩から落下した試料は次の段の篩に加えた。この作業を最下段まで繰り返し行った。
（４）各篩上に残った試料の重量を測定した。
（５）次式により、各篩ごとの粒径分布を求めた。
【数１】

（６）目開きの大きい篩から順に粒径分布の累積値を求めた。
（７）横軸を粒子の大きさ（＝篩の目開き）とし、縦軸を粒径分布の累積値として、（６）で求めたデータをプロットした。次いで、プロットした各点を滑らかな曲線になるように結んだ。
（８）上記の曲線から、累積値が５０（％）のときの粒子の大きさを読み取った。読み取った値をこの試料の平均粒子径とした。
参考例１６〜参考例１８の評価結果を表５に示す。
【００７２】
【表５】

【００７３】
【産業上の利用可能性】
本発明によれば、成形品の外観及び／又は強度に優れる再生発泡性スチレン系樹脂粒子及び再生スチレン系発泡成形品を提供できる。
【００７４】
【図面の簡単な説明】
第１図は、本発明における表層部、さらに、この分子量の測定方法を説明するための図である。
第２図は、本発明における表面部分と中心部分、さらに、これらの分子量の測定方法を説明するための図である。
第３図は、実施例６及び比較例２のＧＰＣチャートである。[0001]
【Technical field】
  The present invention relates to a regenerated expandable styrene resin particle, a regenerated expandable styrene resin particle regenerated from a styrene foam molded product, a method for producing the regenerated expandable styrene resin particle, and a regenerated styrene foam molded product obtained by foaming the same.
[0002]
[Background]
  Conventionally, styrenic foam molded products are used once and then incinerated or heat-shrinked and recovered and reused as polystyrene. However, the reuse rate is insufficient, and the reuse rate will be reduced in the future. Raising it is regarded as a social issue.
  The technology for recovering styrene-based foam molded products as shrinkage lumps has already been completed, and in 1999, about 33% of the styrene-based foam molding products in Japan were recovered as heat-shrinkable lumps. Mainly used for miscellaneous goods by injection molding and building materials by extrusion molding. Thus, at present, the method of reusing styrenic foamed molded products is limited, and the expansion of their uses is urgently needed.
[0003]
  On the other hand, from the definition of recycling, the foamable styrene resin is not foamed styrene rather than being used for other purposes as polystyrene. However, at present, there are few examples in which the styrene resin recovered from the styrene foam-molded product is industrially regenerated as a foamable styrene resin.
  As a method for regenerating foamable styrenic resin from shrinkage of styrene foam moldings, etc., the method of pelletizing the shrinkage with an extruder and impregnating it with a foaming agent is considered the most technically easy. However, in this method, the productivity is determined by the size of the pellet particles. In particular, making particles with a particle size of 0.3 to 1.5 mm, which is in great demand as an expandable styrenic resin, causes a reduction in the discharge rate in the extrusion process, and the productivity is remarkably attributed to mixed dust. Declining, not economical.
[0004]
  As a method for solving these problems, in Japanese Patent Application Laid-Open No. 6-87973, styrene resin particles obtained by non-stretching melt and pulverizing shrinkage of a styrene foam molded article are used as an aqueous solution containing an organic dispersant. There has been proposed a method of producing regenerated expandable styrene resin particles by dispersing in a medium and impregnating a readily volatile foaming agent. Thus, a certain amount of dust is allowed to be mixed, and it is possible to have high productivity even in the impregnation with the foaming agent. However, the recycled foamable styrene resin particles obtained by this method are inferior to the new foamable styrene resin particles in appearance and strength when formed into molded products, so the applied molded products need relatively high strength. Or a new method for mixing with newly produced expandable styrenic resin particles, and mixing with newly produced expandable styrene resin particles. A mixer was required.
[0005]
DISCLOSURE OF THE INVENTION
  An object of the present invention is to provide a regenerated foamable styrene resin particle having excellent appearance, fusion and / or mechanical strength, and a regenerated styrene foam molded article, in which a conventional regenerated foamable styrene resin particle has been a problem. Is to provide.
[0006]
  According to an aspect of the present invention, a core composed of a regenerated styrene resin, and a virgin styrene resin encapsulating the core,As shown in FIG. 2, the particles were equally divided into five equal intervals, and the weight average molecular weight of the surface portion 1 on the most surface side was divided into 5 equally on the innermost portion 5.Recycled foamable styrene resin particles that are 50,000 or more higher than the weight average molecular weight of the central portion are provided.
  According to another aspect of the present invention, there is provided a regenerated styrene expanded bead obtained by foaming the regenerated expandable styrene resin particles.
  According to another aspect of the present invention, there is provided a regenerated styrene foam molded article obtained by molding the above regenerated styrene foam beads.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
  The regenerated foamable styrene resin particles of the present invention and the regenerated styrene foam-molded product obtained by foam-molding the same will be described in detail.
  First, the manufacturing method of the regenerated expandable styrene resin particle of this invention is demonstrated.
  In the production method of the present invention, small particles of a styrenic resin regenerated from used expanded polystyrene are used as nuclei.
[0008]
  The regenerated styrene resin particles used as the core can be obtained by pulverizing a regenerated resin obtained by heating and / or reducing the volume of a used expanded styrene resin. A shrinkage or melt of a styrene resin can be prepared by roughly pulverizing a used styrene resin to an appropriate size as necessary, and then heat shrinkage, bubble breakage shrinkage due to compression, shrinkage due to frictional heat, or melting. . The used expanded styrene-based resin includes not only a molded product obtained by molding a foamable styrene-based resin but also a heat-expanded one.
  A product obtained by extruding the pulverized product to form a pellet, or a product obtained by further pulverizing the pellet may be used as a core. Specific gravity can be adjusted by extruding, and foreign matter can be removed by a screen provided in the extruder.
[0009]
  Further, the regenerated styrenic resin particles can include finely divided inorganic substances and / or organic lubricants. These can function as bubble regulators.
  As the finely divided inorganic substance, talc or calcium carbonate is preferable. Here, talc refers to a mixture containing silicon oxide and magnesium oxide as main components and containing trace amounts of aluminum oxide, iron oxide, and the like. The average particle size of the finely divided inorganic material is preferably 100 μm or less, and more preferably 30 μm or less. If the average particle size of the finely divided inorganic substance exceeds 100 μm, the effect of reducing the bubble size of the resin particles tends to decrease.
[0010]
  The blending amount of the finely divided inorganic substance is preferably in the range of 0.1 to 5% by weight, more preferably in the range of 0.5 to 2% by weight with respect to the regenerated styrene resin particles. If the blending amount of the finely divided inorganic substance is less than 0.1% by weight, the effect of sufficiently reducing the bubble size tends not to be obtained, and if it exceeds 5% by weight, the bubble size becomes extremely small, and at the time of molding. There is a tendency for the resin to melt and the appearance of the molded product to deteriorate.
[0011]
  As the organic lubricant, preferred are higher fatty acid bisatamides such as methylene bisstearylamide, ethylene bisstearylamide, and ethylene bisoleic acid amide, and metal salts of higher fatty acids such as zinc stearate, magnesium stearate, and zinc oleate.
[0012]
  The blending amount of the organic lubricant is preferably in the range of 0.01 to 0.2% by weight and more preferably in the range of 0.02 to 0.1% by weight with respect to the regenerated styrene resin particles. preferable. If the blending amount of the organic lubricant is less than 0.01% by weight, the effect of sufficiently reducing the bubble size tends to be reduced, and if it exceeds 0.2% by weight, the bubble size becomes extremely small and molding is performed. Sometimes the resin melts and the appearance of the molded product tends to be inferior.
[0013]
  Specifically, a finely divided inorganic substance and / or organic lubricant can be kneaded at the time of extrusion molding. In this case, the pulverized product and the air bubble adjusting agent are mixed in advance and then extruded. Mixing of the pulverized product and the bubble adjusting agent can be performed by a conventionally known means. For example, a blender such as a ribbon blender, a V blender, a Henschel mixer, or a ready game mixer can be used.
[0014]
  The shrinkage or melt of the used expanded styrene resin is preferably prepared by excluding the used styrene expanded molded product that has been colored with a dye or the like in advance. If a colored molded product is mixed, the regenerated expandable styrene resin particles and foamed molded product obtained from the colored product are colored, which is not preferable.
[0015]
  The styrene resin shrinkage or melt is preferably heat-melted for the purpose of adjusting the specific gravity. In this step, the specific gravity of the regenerated styrene resin is preferably adjusted to 0.6 or more, more preferably 0.9 or more. When the specific gravity is less than 0.6, the dispersion of the resin particles is unstable, so that excessive particles are generated during the polymerization process, and the yield tends to be lowered. Conventionally known means such as an extruder and a hot roll can be used for the thermal melting of the styrene resin.
[0016]
  In this thermal melting, it is important that the obtained resin is cooled and solidified with no strain remaining or with a small strain. If the resin particles remain strained, the strain is relaxed in the polymerization process and the foaming agent impregnation process and contracts in the stretching direction, and the obtained regenerated expandable styrene resin particles may not be spherical but flat. is there. Therefore, it is preferable to perform non-stretch melting with an extruder. When heat melting is performed in a stretched state, strain remains in the stretched resin obtained by cooling and solidifying.
  However, even if strain remains in the resin in the heat melting step, the strain can be alleviated by curing for a certain time at a temperature equal to or higher than the softening point of the resin.
  Although the thing for plastics can apply the grinder which grind | pulverizes recycled resin, if it can grind | pulverize in the range of 0.3-3 mm aiming at polystyrene, it will not be limited.
[0017]
  Regenerated styrenic resin particles having a size other than the purpose obtained by pulverization are sieved and can be subjected again to a melting step by an extruder or the like.
  The average diameter of the nuclei made of regenerated styrene resin particles is preferably 0.2 mm or more, more preferably 0.4 mm or more, and particularly preferably 0.5 mm or more. Moreover, 3 mm or less is preferable, less than 2 mm is more preferable, and 1.7 mm or less is more preferable.
  If the size of the regenerated styrene resin particles exceeds 3 mm, the product shape tends to be difficult to be spherical. If the regenerated styrene resin particles are less than 0.2 mm, the particle diameter is too small even after polymerization, When demand is low.
  The regenerated styrene resin particles as the core preferably have a particle content of 300 μm or less and less than 1% by weight. If the content of particles of 300 μm or less is 1% by weight or more, the appearance of the molded product may be deteriorated.
[0018]
  The weight average molecular weight of the regenerated styrene resin particles as the core is preferably 100,000 or more and 250,000 or less. If the weight average molecular weight of the regenerated styrene resin particles is less than 100,000, sufficient strength tends not to be obtained, and if it exceeds 250,000, the particles tend not to be spheroidized. More preferably, it is 150,000 to 230,000.
[0019]
  The ratio of the regenerated styrene resin particles as the core is 30% by weight or more and 70% by weight or less, and preferably 30% by weight or more and 50% by weight or less. If the ratio of the regenerated styrene resin particles is less than 30% by weight, the particles are easily united in the polymerization process, and if it exceeds 70% by weight, sufficient strength may not be obtained.
[0020]
  In the method for producing regenerated expandable styrene resin particles of the present invention, first, regenerated styrene resin particles are suspended in an aqueous medium as a core. Dispersion in an aqueous medium is usually performed using an apparatus equipped with a stirring blade, and there are no restrictions on the conditions. Moreover, it is preferable to disperse | distribute with a dispersing agent.
[0021]
  The dispersant used in the present invention is not particularly limited as long as it is used for suspension polymerization. Examples thereof include organic dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone and methyl cellulose, and poorly soluble inorganic salts such as magnesium phosphate and tricalcium phosphate. Further, a surfactant can also be used. As this surfactant, any of sodium oleate, sodium dodecylbenzenesulfonate, and other anionic surfactants and nonionic surfactants generally used in suspension polymerization can be used. Among these dispersants, it is preferable to use an organic dispersant from the viewpoint of the stability of the oil droplets of the styrene monomer.
[0022]
  Next, a styrene monomer in which a polymerization initiator is dissolved in advance is added to the suspension, impregnated into regenerated styrene resin particles as a core, and then the styrene monomer is added to perform polymerization.
  The styrenic monomer used in the present invention is one or more of styrene and a styrene derivative such as α-methylstyrene and vinyltoluene, or a methacrylic acid ester such as methyl methacrylate and ethyl methacrylate. And combinations with other polymerizable monomers such as vinyl cyanide such as acrylate, acrylonitrile and methacrylonitrile, and vinyl chloride. In addition, a crosslinking agent such as divinylbenzene or diallyl phthalate may be used.
[0023]
  The polymerization initiator may be added after being dissolved in a solvent, and may be impregnated with regenerated styrenic resin particles serving as a nucleus. As the solvent, aromatic hydrocarbons such as ethylbenzene and toluene, and aliphatic hydrocarbons such as heptane and octane are used. When the solvent is used, it is usually used at 3% by weight or less based on the styrene monomer. Is done.
  The polymerization initiator used in the polymerization reaction is not particularly limited as long as it is used in the suspension polymerization method, and examples thereof include organic substances such as benzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, and t-butyl perbenzoate. One or more of azo compounds such as peroxide and azobisisobutyronitrile can be used.
  Although the usage-amount of a polymerization initiator changes with kinds of polymerization initiator, generally the range of 0.1 to 0.5 weight% is preferable with respect to a monomer. The polymerization initiator is added after being dissolved in a styrene monomer or solvent. As this solvent, aromatic hydrocarbons such as ethylbenzene and toluene, aliphatic hydrocarbons such as heptane and octane, etc. are used. When these are used, the amount is usually 3% by weight or less based on the styrene monomer. used.
[0024]
  As a method of impregnating a styrene monomer into a core composed of regenerated styrene resin particles dispersed in an aqueous medium, a method of adding a styrene monomer alone, a styrene monomer in an aqueous medium, or Alternatively, there is a method of adding as a dispersion finely dispersed by adding a dispersant or the like. Moreover, you may combine these methods.
  A method of adding a styrenic monomer, a dispersant, or the like to an aqueous medium to finely disperse is usually performed using an apparatus equipped with a stirring blade. The conditions are not limited, but it is preferable to use a homomixer as a method for finer dispersion. At this time, it is preferable to disperse until the oil droplet diameter of the dispersion liquid in which the styrene monomer is dispersed is equal to or smaller than the particle diameter of the core. When added to an aqueous medium in a state where the oil droplet size is larger than the core particle size, a plurality of resin particles are taken into the oil droplets of the dispersion liquid in which the styrenic monomer is dispersed, and the resin particles are adhered and plasticized. This is because crystallization and coalescence occur and excessive particles are easily generated.
[0025]
  The addition of the styrenic monomer may be performed separately or continuously. Further, the addition rate varies depending on the capacity, shape, polymerization temperature, etc. of the polymerization apparatus and is appropriately selected. The polymerization temperature is preferably in the range of 60 to 105 ° C.
  Further, in the present invention, fatty acid monoamides such as oleic acid amide and stearic acid amide, fatty acid bisamides such as methylene bis stearic acid amide and ethylene bis stearic acid amide, etc. are dissolved in the styrenic monomer or the solvent as a bubble regulator. May be used.
[0026]
  The foaming agent is press-fitted into the container during or after the polymerization and is usually raised to a temperature equal to or higher than the softening point of the regenerated styrene resin particles, and the foaming agent is impregnated into the resin particles. As the foaming agent, those that do not dissolve or slightly swell resin particles are preferable. Specifically, aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, cyclohexane, cyclohexane Alicyclic hydrocarbons such as pentane are used. These foaming agents are usually used in an amount of 3 to 15% by weight based on the regenerated styrene resin particles.
  When impregnated with a foaming agent, a flame retardant can also be impregnated to increase the flame retardancy.
[0027]
  The flame retardant is preferably a bromine compound that is compatible with polystyrene. As the bromine compound, tetrabromoethane, hexabromocyclododecane, 2,2-bis (4-allyloxy-3,5-dibromo) propane, hexabromobenzene and the like are preferable. Further, it can be used in combination with a peroxide such as dicumyl peroxide. These are preferably used in an amount of 0.5 to 5% by weight, more preferably 1.5 to 3.5% by weight, based on the regenerated styrene resin particles. If it is less than 0.5% by weight, the flame retardancy is lowered, and if it exceeds 5% by weight, the moldability tends to be inferior.
  The flame retardant is preferably added after being uniformly dispersed in an aqueous solution containing a surfactant by a stirrer. When the flame retardant is added directly without making it an aqueous solution, the dispersion of the flame retardant becomes insufficient, and the absorption to the regenerated styrene resin particles decreases. In particular, this tendency is remarkable in powder flame retardants.
[0028]
  The regenerated expandable styrene resin particles can be coated with a surface coating agent as necessary after impregnation of the foaming agent (and flame retardant) is completed, discharged from the polymerization system, and further dehydrated and dried. As this coating agent, those used for conventionally known expandable styrene resin particles can be applied. For example, zinc stearate, stearic acid triglyceride, stearic acid monoglyceride, castor hardened oil, beef tallow hardened oil, silicones, antistatic agent and the like.
[0029]
  The total molecular weight can be adjusted by adjusting the concentration of the polymerization initiator, using a chain transfer agent together, or both. As the chain transfer agent, conventionally known ones such as octyl mercaptan, dodecyl mercaptan, α-methylstyrene dimer can be used. Usually, the overall molecular weight increases as the concentration of the polymerization initiator decreases.
  Therefore, by adjusting the concentration of the polymerization initiator and the like, the weight average molecular weight of the regenerated expandable styrene resin particles is 150% or more and less than 300% with respect to the weight average molecular weight of the regenerated styrene resin particles as the core. Regenerated expandable styrene resin particles are obtained.
  Further, by reducing the oxygen concentration, the weight average molecular weight in the vicinity of the surface of the regenerated expandable styrene resin particles can be increased.
[0030]
  Specifically, when the content of the styrene monomer is 20% or less, the polymerization average molecular weight can be adjusted by keeping the oxygen concentration in the reaction vessel at 7% by volume or less. Preferably, the styrene monomer is added while keeping the oxygen concentration at 5% by volume or less, more preferably at 1% by volume or less. “The content of the styrene monomer is 20% or less” means that the content in the reaction system is 20% in the latter half of the polymerization when the content is 0% when all of the added styrene monomer is polymerized. When it becomes less than%.
  When the content of the styrene monomer is 20% or less, by keeping the oxygen concentration in the reaction vessel at 7% by volume or less, the molecular weight of the surface part is suppressed, and the weight average molecular weight of the surface part is reduced. , And can be adjusted to be 50,000 or more higher than the central portion. If the oxygen concentration exceeds 7% by volume, the surface portion will not be sufficiently high in molecular weight, and the appearance and strength of the resulting molded product of regenerated foam styrene resin may be reduced.
  Furthermore, preferably, the weight average molecular weight of the surface portion is further increased by maintaining the oxygen concentration in the reaction vessel at 1% by volume or less from the start of polymerization until the content of the styrene monomer reaches 3%. can do.
  The oxygen concentration in the reaction vessel can be adjusted by replacing the air in the reaction vessel with an inert gas such as nitrogen.
[0031]
  According to this manufacturing method, the weight average molecular weight of the surface portion that forms 1/5 from the surface divided into 5 equal parts from the surface of the particle to 1/5, forms 1/5 from the center toward the surface. Thus, regenerated expandable styrene resin particles having a weight average molecular weight higher than that of the central portion are obtained. It is thought that the molecular weight gradient from the center to the surface does not gradually increase at a constant rate but suddenly increases near the surface.
[0032]
  Here, the surface portion and the central portion will be described with reference to the drawings. As shown in FIG. 1, the resin particles 10 are divided into five equal parts from the surface toward the center. The outermost part 1 forming 1/5 from the surface is the surface part. The weight average molecular weight of the surface portion is the weight average molecular weight of this portion 1. The innermost portion 5 that forms 1/5 from the center is the central portion. The weight average molecular weight of the central portion is the weight average molecular weight of the center obtained by dividing the portion 5 into 5 equal parts.
  Furthermore, when the oxygen concentration in the reaction vessel is kept at 1% by volume or less from the start of polymerization to the end of polymerization (for example, when the content of styrene monomer is 3%), the molecular weight of the surface portion is further increased. . At the end of the polymerization reaction, that is, at a portion very close to the surface, the molecular weight that has risen tends to decrease. However, if the oxygen concentration in the reaction vessel is kept at 1% by volume or less, the decrease can be suppressed. It is done.
[0033]
  In general, when the molecular weight is low, the foaming property and the fusion property are excellent, and when the molecular weight is high, the appearance and the strength of the molded product tend to be excellent. That is, the foaming and fusing properties, the appearance and the strength of the molded product are contradictory properties. In the re-expandable styrene resin particles obtained by reducing the oxygen concentration, the molecular weight of the surface portion can be made high, while the molecular weight of the central portion is kept low. With these particles, all of foamability, appearance, and molded product strength can be satisfied. For example, while maintaining a certain degree of foamability, the appearance is excellent and a considerably high strength of the molded product can be obtained.
  Furthermore, it is preferable that the chart by the gel permeation chromatography method of the surface part of this particle | grain has a mountain or a shoulder. Having two peaks or shoulders means that the molecular weight is changing rapidly. ShoulderInflection pointIt is formed by. Having two peaks or shoulders means that the molecular weight distribution is not a normal distribution, and low molecular weight and high molecular weight are unevenly distributed. In the present invention, the chart by gel permeation chromatography is measured using two columns, GL-R400M, manufactured by Hitachi Chemical Co., Ltd. Note that inflection points are also generated at both tails of the normal chart, but these are not included in the shoulder in the present invention (see FIG. 3).
[0034]
  As described above, generally, when the molecular weight is low, the foaming property and the fusion property are excellent, and when the molecular weight is high, the appearance and the strength of the molded product tend to be excellent. When the molecular weight of the surface portion is high, the appearance and the strength of the molded product are excellent, but the fusing property tends to decrease. By making the low molecular weight and high molecular weight unevenly distributed on the surface portion, it is possible to improve the fusion property while maintaining an excellent appearance and high strength of the molded product.
  In particular, the weight average molecular weight of the surface part of the regenerated expandable styrene resin particles is preferably 50,000 or more higher than the center part and 100,000 or more higher. If the difference in weight average molecular weight is less than 50,000, the appearance and strength may not be sufficiently improved.
[0035]
  The regenerated foam molded article of the present invention is produced by foam molding regenerated foamable styrene resin particles.
  In general, regenerated expandable styrene resin particles are heated with steam or the like to be pre-foamed to a predetermined bulk density, filled with foam beads that have undergone an aging process, and again heated and foamed with steam or the like, Manufacture foam molded products.
  The molded product of the present invention is excellent in appearance, fusion and / or strength, and can be suitably used for food containers, packing materials, cushioning materials and the like.
[0036]
【Example】
  Examples of the present invention will be described below.
[Production of regenerated foamable styrene resin particles]
Reference example 1
(Manufacture of nuclei made of regenerated styrene resin particles)
  A foamed styrene-based resin molded product (molded product obtained from Hitachi Chemical Co., Ltd. High Beads SSB-HX) is shrunk with hot air at 220 ° C., apparent specific gravity 0.75, size 500 mm × 400 mm × 100 mm and weight A shrinkage of 15 kg was obtained. The shrinkage was roughly pulverized with a pulverizer (ZA-560 type pulverizer, trade name of Horai Co., Ltd.) equipped with a 10 mm screen. The maximum length of the coarsely pulverized product obtained at this time was approximately 10 mm and the bulk specific gravity was 0.5.
  Next, this coarsely pulverized product was melt extruded using a vented 30 mm extruder (T-shaped die, sheet width 300 mm, sheet wall pressure 1 mm) while pulling the sheet at approximately the same speed as the extrusion speed.
  Furthermore, before cooling and solidification, a slit having a 1 mm interval and a depth of 0.5 mm was provided by a roll horizontally with respect to the extrusion direction, and after cooling and solidification, it was cut into about 10 to 15 cm by a cutting machine. Subsequently, the obtained sheet-like styrene-based resin cut piece was finely pulverized by a pulverizer (VM-16 type pulverizer, Orient product name) equipped with a 2 mm screen. The finely pulverized product was classified with a sieve in a range of 0.6 to 0.85 mm to obtain regenerated styrene resin particles. The weight average molecular weight of the regenerated styrene resin particles was 172,000.
(Manufacture of regenerated foamable styrene resin particles (regenerated foamable particles))
  A 5 liter pressure-resistant stirring vessel was charged with 600 g of deionized water, 700 g of the above regenerated styrene resin particles, 6.0 g of tricalcium phosphate, and 0.06 g of sodium dodecylbenzenesulfonate, and the temperature was raised to 85 ° C. while stirring.
  Next, 1400 g of deionized water and 1.4 g of polyvinyl alcohol are placed in a monomer dispersion container and mixed, and 3.7 g of benzoyl peroxide and 1300 g of styrene monomer in which 1.12 g of t-butyl perbenzoate is dissolved are added. Then, the mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Koki Kogyo Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added into the vessel at an equal rate over 3 hours (addition rate was 15 g / min), and the temperature was further maintained for 2 hours. Thereafter, the temperature was raised to 100 ° C., and butane (i / n ratio = 4/6, weight ratio is the same below) as a blowing agent was injected in 90 g portions in two portions. After completion of butane press-fitting, the temperature was raised to 115 ° C. and maintained for 10 hours to impregnate the foaming agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. The average molecular weight of the polymer particles was 23,000.
  Next, the polymer particles were classified with a sieve having an opening of 1.7 mm, and the weight of the resin particles remaining on the sieve was measured as oversized particles.
  Further, the particles are classified with a sieve having an aperture of 0.6 mm, and the resin particles remaining on the sieve are coated with 0.1 wt% zinc stearate and 0.1 wt% hardened castor oil to cover the surface, and regenerated foamable styrene resin particles. Got.
  The regenerated foamable styrene resin particles obtained were prefoamed to 50 ml / g, and after aging for about 18 hours, molded using a foamed styrene resin molding machine VS-300 manufactured by Daisen Industry at a molding pressure of 0.08 MPa. A molded product was obtained.
[0037]
Reference example 2
(Manufacture of recycled foam particles)
  1800 g of deionized water in a 5 liter pressure-resistant stirring vessel,Reference example 11000 g of the regenerated styrene resin particles (weight average molecular weight: 172,000) produced in 1), tricalcium phosphate 9.0 g, and sodium dodecylbenzenesulfonate 0.1 g were charged, and the temperature was raised to 60 ° C. with stirring.
  Next, 350 g of deionized water and 0.3 g of polyvinyl alcohol were placed in a monomer dispersion container and mixed. To this was added 250 g of a styrene monomer in which 0.3 g of t-butylperoxy-2-ethylhexyl carbonate was dissolved. The mixture was stirred at 5800 rpm for 120 seconds using a mixer (made by Koki Kogyo Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container, and then kept warm for 1 hour, and then heated to 80 ° C.
  Next, 350 g of deionized water and 0.2 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 170 g of a styrene monomer in which 4.0 g of benzoyl peroxide is dissolved is added thereto. ) Was stirred at 5800 rpm for 120 seconds to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container, kept warm for 90 minutes, and then heated to 90 ° C.
  Thereafter, 1050 g of styrene monomer was continuously added at an equal rate over 4 hours (addition rate was 4.4 g / min).
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Thereafter, it was cooled to 100 ° C., butane (i / n ratio = 4/6) as a blowing agent was injected in 110 g portions in two portions, and held for 10 hours to impregnate the blowing agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. The weight average molecular weight of the polymer particles was 225,000. afterwards,Reference example 1Classification, surface coating, pre-foaming, and molding were performed in the same manner as described above.
[0038]
Reference example 3
  A 5 liter pressure-resistant stirring vessel was charged with 200 g of deionized water, 200 g of regenerated styrene resin particles, 1.8 g of tricalcium phosphate, and 0.02 g of sodium dodecylbenzenesulfonate, and the temperature was raised to 85 ° C. while stirring.
  Next, 1800 g of deionized water and 1.9 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 5.1 g of styrene monomer in which 5.1 g of benzoyl peroxide and 1.55 g of t-butyl perbenzoate are dissolved is added thereto. The mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added into the vessel at an equal rate over 3 hours (addition rate was 15 g / min), and the temperature was further maintained for 2 hours. Thereafter, the temperature was raised to 100 ° C., and butane (i / n ratio = 4/6) as a blowing agent was injected in 90 g portions in two portions. After completion of butane press-fitting, the temperature was raised to 115 ° C. and maintained for 10 hours to impregnate the foaming agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. The average molecular weight of the polymer particles was 201,000. afterwards,Reference example 1Classification, additive surface coating, pre-foaming, and molding were performed in the same manner as described above.
[0039]
Reference example 4
(Manufacture of nuclei)
  Reference example 1The finely pulverized product prepared in (1) was classified with a sieve into a range of 0.6 to 1.4 mm to obtain regenerated styrene resin particles (weight average molecular weight 172,000, specific gravity 1.02).
(Manufacture of recycled foam particles)
  1000 g of the above regenerated styrene resin particles, 1500 g of deionized water, 0.5 g of polyvinyl alcohol, 5 g of tricalcium phosphate and 0.08 g of sodium dodecylbenzenesulfonate were placed in a pressure-resistant reaction kettle having an internal volume of 4 liters, and then stirred. A dispersion obtained by stirring 500 g of deionized water, 0.06 g of sodium dodecylbenzenesulfonate, and 5 g of toluene with a homomixer (manufactured by Special Processing Industry Co., Ltd.) for 5 minutes was added, and after heating to 90 ° C., butane (i / n ratio = 4/6) was injected in 45 g portions in two portions. After maintaining for 1 hour, the temperature was raised to 115 ° C. and maintained for 10 hours to impregnate the foaming agent.
  After cooling to room temperature, the recycled foamable styrene resin particles impregnated with the blowing agent are taken out, dehydrated and dried.Reference example 1Classification, additive surface coating, pre-foaming, and molding were performed in the same manner as described above.
[0040]
Reference Example 5
(Manufacture of recycled foam particles)
  500 g of deionized water in a 5 liter pressure-resistant stirring vesselReference example 1700 g of the regenerated styrene-based resin particles prepared in Step 1, 6.0 g of tricalcium phosphate, and 0.06 g of sodium dodecylbenzenesulfonate were charged, and the temperature was raised to 85 ° C. while stirring.
  Next, 1300 g of deionized water and 1.4 g of polyvinyl alcohol are placed in a container in which the monomer is dispersed and mixed, and 1300 g of styrene monomer in which 3.7 g of benzoyl peroxide and 1.12 g of t-butyl perbenzoate are dissolved. Was added and stirred at 5800 rpm for 120 seconds using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added into the vessel at an equal rate over 3 hours (addition rate was 15 g / min), and further kept warm for 2 hours. Next, a flame retardant dispersion in which 400 g of deionized water, 0.12 g of sodium dodecylbenzenesulfonate, and 60 g of hexabromocyclododecane were stirred with a homomixer for 30 minutes was added. After the addition of the flame retardant dispersion, the temperature was raised to 100 ° C. and butane (i / n ratio = 4/6 weight ratio; the same applies hereinafter) as a blowing agent was injected in 90 g portions in two portions. After completion of butane press-fitting, the temperature was raised to 115 ° C. and maintained for 10 hours to impregnate the foaming agent.
  After cooling to room temperature, the regenerated flame retardant styrene resin particles impregnated with the flame retardant and the foaming agent were taken out and dehydrated and dried. The average molecular weight of the polymer particles was 225,000. afterwards,Reference example 1Classification, surface coating, pre-foaming, and molding were performed in the same manner as described above.
[0041]
Reference Example 6
(Manufacture of recycled foam particles)
  1300 g of deionized water in a 5 liter pressure-resistant stirring vessel,Reference example 11000 g of the styrene resin particles (weight average molecular weight: 172,000) prepared in 1), 9.0 g of tricalcium phosphate, and 0.1 g of sodium dodecylbenzenesulfonate were charged, stirred, and heated to 60 ° C.
  Next, 350 g of deionized water and 0.3 g of polyvinyl alcohol were placed in a monomer dispersion container and mixed. To this was added 250 g of a styrene monomer in which 0.3 g of t-butylperoxy-2-ethylhexyl carbonate was dissolved. The mixture was stirred at 5800 rpm for 120 seconds using a mixer (made by Koki Kogyo Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container, and then kept warm for 1 hour, and then heated to 80 ° C.
  Next, 350 g of deionized water and 0.2 g of polyvinyl alcohol were mixed in a container in which the monomer was dispersed, and 170 g of styrene monomer in which 4.0 g of benzoyl peroxide was dissolved was added thereto. The styrene monomer was finely dispersed (average monomer oil droplet diameter of 10 to 100 μm) by stirring at 5800 rpm for 120 seconds using an industrial product. This styrene monomer dispersion was added to the container, kept warm for 90 minutes, and then heated to 90 ° C.
  Subsequently, 1050 g of styrene monomer was continuously added at an equal rate (addition rate was 4.4 g / min) over 4 hours.
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Then, it cooled to 100 degreeC and the flame retardant dispersion liquid which stirred deionized water 500g, sodium dodecylbenzenesulfonate 0.15g, and hexabromocyclododecane 75g with the homomixer for 30 minutes was added. After adding the flame retardant dispersion, 110 g of butane (i / n ratio = 4/6) as a blowing agent was injected in two portions of 110 g and maintained for 10 hours to impregnate the flame retardant and the blowing agent.
  After cooling to room temperature, the regenerated flame retardant styrene resin particles impregnated with the flame retardant and the foaming agent were taken out and dehydrated and dried. The weight average molecular weight of the polymer particles was 2280,000. afterwards,Reference example 1Classification, additive surface coating, pre-foaming, and foam molding were performed in the same manner as above.
[0042]
Reference Example 7
(Manufacture of nuclei)
  Reference example 1The finely pulverized product prepared in (1) was classified into a range of 0.6 to 1.4 mm with a sieve to obtain regenerated styrene resin particles (weight average molecular weight 172,000, specific gravity 1.02).
(Manufacture of recycled foam particles)
  Contains 1000 g of the above regenerated styrene resin particles (weight average molecular weight 172,000, specific gravity 1.02), 1500 g of deionized water, 0.5 g of polyvinyl alcohol, 5 g of tricalcium phosphate, and 0.08 g of sodium dodecylbenzenesulfonate. The mixture was stirred in a 4 liter pressure-resistant reactor, and then 500 g of deionized water, 0.06 g of sodium dodecylbenzenesulfonate, 5 g of toluene, and 30 g of hexabromocyclododecane were stirred for 30 minutes with a homomixer (manufactured by Special Processing Industry). After the dispersion was added and the temperature was raised to 90 ° C., butane (i / n ratio = 4/6) as a blowing agent was injected in 45 g portions in two portions. After maintaining for 1 hour, the temperature was raised to 115 ° C. and maintained for 10 hours to impregnate the foaming agent.
  After cooling to room temperature, the recycled flame retardant styrene resin particles impregnated with the blowing agent are taken out, dehydrated and dried,Reference example 1Classification, additive surface coating, pre-foaming, and foam molding were performed in the same manner as above.
[0043]
Evaluation Example 1
  Reference examples,ExampleComparative exampleThe weight average molecular weight was measured by HPLC.
  The surface smoothness and bending strength were measured as follows.
(1) Surface smoothness
  The surface smoothness of the foamed molded product was defined as the surface smoothness by coating the surface of the molded product with a thin layer of printing ink with a roller and applying this surface portion to an image processing apparatus to determine the area of the black portion relative to the total area.
(2) Bending strength
  The bending strength test was performed according to JIS-K-7221 using a foamed molded product (300 × 25 × 20 mm) having a density of 0.02 g / l.
  Reference example 1~Reference Example 7The evaluation results are shown in Table 1.
[0044]
[Table 1]

[0045]
[Effect of polymerization initiator in the production of regenerated expandable styrene resin particles]
Reference Example 8
(Manufacture of nuclei)
  A foamed styrenic resin molded product (molded product obtained from Hitachi Chemical Co., Ltd. High Beads SSB-HX) is shrunk with hot air at 220 ° C., apparent specific gravity 0.8, size 500 mm × 400 mm × 100 mm and weight About 16 kg of shrinkage was obtained. The shrinkage was roughly pulverized with a pulverizer (ZA-560 type pulverizer, trade name of Horai Co., Ltd.) equipped with a 10 mm screen. The maximum length of the coarsely pulverized product obtained at this time was approximately 10 mm and the bulk specific gravity was 0.65. Next, 2000 g of this coarsely pulverized product, 20 g of talc (Hayashi Kasei Co., Ltd., Micro White # 5000) having an average particle size of 10 μm and 0.6 g of ethylene bisstearyl amide are placed in a Henschel mixer (manufactured by Mitsui Miike Chemical, FM10B) at 2000 rpm. Mix for 2 minutes. This coarsely pulverized material coated with talc and ethylene bisstearyl amide is melt-extruded while pulling the sheet at approximately the same speed as the extrusion speed using a vented 30 mm extruder (T die, sheet width 300 mm, sheet wall pressure 1 mm). did. Further, before cooling and solidification, a slit having a 1 mm interval and a depth of 0.5 mm was provided by a roll horizontally with respect to the extrusion direction. Subsequently, the obtained sheet-like styrene-based resin cut piece was finely pulverized by a pulverizer (VM-16 type pulverizer, Orient product name) equipped with a 2 mm screen. The finely pulverized product was classified with a sieve in a range of 0.6 to 1.2 mm to obtain regenerated styrene resin particles.
  The regenerated styrene resin particles had a weight average molecular weight of 169,000 and a specific gravity of 0.91.
(Manufacture of recycled foam particles)
  A 5 liter pressure-resistant stirring vessel was charged with 1900 g of deionized water, 1100 g of the above regenerated styrene resin particles, 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate, and the temperature was raised to 75 ° C. while stirring.
  Next, 400 g of deionized water and 1.3 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 200 g of styrene monomer in which 0.2 g of t-butyl peroxide and 2.9 g of benzoyl peroxide are dissolved is added. The mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container, kept warm for 60 minutes, and then heated to 90 ° C. Subsequently, 900 g of styrene monomer was continuously added at an equal rate (3.0 g / min) over 5 hours.
  Subsequently, after adding 2.2 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Next, the mixture was cooled to 100 ° C., and 180 g of butane (i / n ratio = 4/6, the same as the weight ratio) 180 g as a blowing agent was injected in two portions and held for 10 hours to impregnate the blowing agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. The average molecular weight of the resin particles was 27,000.
  Next, the resin particles are classified with a sieve having an aperture of 0.6 mm to 1.7 mm, and 0.1% by weight of zinc stearate and 0.1% by weight of hardened castor oil are added to the obtained resin particles for surface coating and regeneration. Expandable styrene resin particles were obtained.
  The regenerated foamable styrene resin particles obtained were prefoamed to 50 ml / g, and after aging for about 18 hours, molded using a foamed styrene resin molding machine VS-300 manufactured by Daisen Industry at a molding pressure of 0.08 MPa. A molded product was obtained.
[0046]
Reference Example 9
  Reference Example 8Except that 2.3 g of benzoyl peroxide is used.Reference Example 8In the same manner as above, regenerated expandable styrene resin particles were obtained. At this time, the weight average molecular weight of the obtained regenerated expandable styrene resin particles was 322,000.
[0047]
Reference Example 10
  Reference Example 8In the above, except that the benzoyl peroxide is 1.65 g,Reference Example 8In the same manner as above, regenerated expandable styrene resin particles were obtained. At this time, the weight average molecular weight of the obtained regenerated expandable styrene resin particles was 43,000.
[0048]
Evaluation example 2
  Reference Example 8~Reference Example 10The weight average molecular weight of the surface layer was measured as follows.
  The molecular weight of the expandable styrene resin particles was measured by expanding the particles. While observing with a microscope using a part of the resin particles foamed to 50 ml / g, the particles 10 were divided into nine equal parts with a razor as shown in FIG. The weight average molecular weight of the surface layer portion S on the most surface side was measured.
  The molecular weight was measured by HPLC under the following conditions.
  Column: 2 GL-R400M (φ10.7 × 300mm)
  Column temperature: room temperature
  Eluent: THF
  Flow rate: 2.0 mL / min
  Detector: UV 220nm
  Injection volume: 100 μL
  Reference Example 8~Reference Example 10The evaluation results are shown in Table 2.
[0049]
[Table 2]

[0050]
[Effect of oxygen concentration in the production of regenerated expandable styrene resin particles]
Example 1
(Manufacture of nuclei)
  Reference example 1In the same manner as above, a regenerated styrene resin having a weight average molecular weight of 20 million was obtained.
(Manufacture of recycled foam particles)
  A 5 liter pressure-resistant stirring vessel is charged with 1700 g of deionized water, 1000 g of the above regenerated styrene resin particles (core), 10.0 g of tricalcium phosphate, and 0.08 g of sodium dodecylbenzenesulfonate, stirred, and heated to 70 ° C. did.
  Next, 300 g of deionized water and 0.36 g of polyvinyl alcohol are mixed in a monomer dispersion container, and styrene monomer in which 2.70 g of benzoyl peroxide and 0.20 g of t-butylperoxyisopropyl monocarbonate are dissolved. 300 g was added, and the mixture was stirred at 5800 rpm for 120 seconds using a homomixer (made by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets 10 to 100 μm). This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 30 minutes, and then heated to 90 ° C.
  Thereafter, 700 g of styrene monomer was continuously added at a constant rate over 3 hours. At this time, the inside of the pressure-resistant stirring vessel was purged with nitrogen to keep the oxygen concentration at 2 to 5% by volume. The polymerization rate after 3 hours was 85%.
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. During this time, the above oxygen concentration was maintained. The polymerization rate after 2 hours was 98% or more. Thereafter, it was cooled to 100 ° C., butane (i / n ratio = 4/6) as a blowing agent was injected in 100 g portions in two portions, held for 10 hours, and impregnated with the blowing agent.
  After cooling to room temperature, the styrene resin particles impregnated with the blowing agent were taken out and dehydrated and dried.
  Next, the polymer particles are classified with a sieve having an opening of 1.7 mm, and the polymer particles having passed through the sieve are further classified with a sieve having an opening of 0.6 mm, and zinc stearate is added to the resin particles remaining on the sieve. 0.1% by weight and 0.1% by weight of hardened castor oil were added to coat the surface to obtain regenerated expandable styrene resin particles.
  The regenerated foamable styrene resin particles obtained were foamed to 50 ml / g, aged for about 18 hours, and then molded at a molding pressure of 0.08 MPa using a foamed styrene resin molding machine VS-300 manufactured by Daisen Industry. I got a product.
  In Examples, the polymerization rate was measured by collecting resin particles during synthesis and using the following apparatus and conditions.
    Measuring device: manufactured by Hitachi, Ltd.
    Eluent: acetonitrile / distilled water = 70/30, flow rate: 1 ml / min
    Detector: UV 230nm
    Column: Inertsil ODS-2
[0051]
Example 2
(Manufacture of recycled foam particles)
  1700 g of deionized water in a 5 liter pressure-resistant stirring vessel,Example 11000 g of regenerated styrene resin particles (core) prepared by the same method, 10.0 g of tricalcium phosphate and 0.08 g of sodium dodecylbenzenesulfonate were charged, stirred and heated to 70 ° C.
  Next, 300 g of deionized water and 0.36 g of polyvinyl alcohol are mixed in a monomer dispersion container, and styrene monomer in which 2.70 g of benzoyl peroxide and 0.20 g of t-butylperoxyisopropyl monocarbonate are dissolved. 300 g was added, and the mixture was stirred at 5800 rpm for 120 seconds using a homomixer (made by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets 10 to 100 μm). This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 30 minutes, and then heated to 90 ° C.
  Thereafter, 700 g of styrene monomer was continuously added at a constant rate over 3 hours. At this time, the inside of the pressure-resistant stirring vessel was purged with nitrogen to keep the oxygen concentration at 0.5% by volume or less. The polymerization rate after 3 hours was 93%.
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. During this time, the above oxygen concentration was maintained. The polymerization rate after 2 hours was 98% or more. Thereafter, it was cooled to 100 ° C., butane (i / n ratio = 4/6) as a blowing agent was injected in 100 g portions in two portions, held for 10 hours, and impregnated with the blowing agent.
  After cooling to room temperature, the styrene resin particles impregnated with the blowing agent were taken out and dehydrated and dried. afterwards,Example 1Classification, surface coating with additives, foaming, and molding in the same manner as described above.
[0052]
Example 3
(Manufacture of recycled foam particles)
  Example 2Except that the oxygen concentration in the reaction vessel was kept at 1% by volume or less by purging with nitrogen from the beginning.Example 2And manufactured in the same manner.
[0053]
Comparative Example 1
(Manufacture of recycled foam particles)
  As a comparison, regenerated expandable styrene resin particles were produced without reducing the oxygen concentration.
  1700 g of deionized water in a 5 liter pressure-resistant stirring vessel,Reference example 11000 g of regenerated expandable styrene resin particles prepared in the same manner as above, 10.0 g of tricalcium phosphate and 0.08 g of sodium dodecylbenzenesulfonate were charged, stirred and heated to 70 ° C.
  Next, 300 g of deionized water and 0.36 g of polyvinyl alcohol are mixed in a monomer dispersion container, and styrene monomer in which 2.70 g of benzoyl peroxide and 0.20 g of t-butylperoxyisopropyl monocarbonate are dissolved. 300 g was added, and the mixture was stirred at 5800 rpm for 120 seconds using a homomixer (made by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets 10 to 100 μm). This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 30 minutes, and then heated to 90 ° C.
  Thereafter, 700 g of styrene monomer was continuously added at a constant rate over 3 hours. Under the present circumstances, when superposition | polymerization was advanced without carrying out nitrogen purge inside the pressure-resistant stirring container, oxygen concentration was 17-20 volume%. At this time, the polymerization rate was 85%.
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Thereafter, it was cooled to 100 ° C., butane (i / n ratio = 4/6) as a blowing agent was injected in 100 g portions in two portions, held for 10 hours, and impregnated with the blowing agent.
  After cooling to room temperature, the styrene resin particles impregnated with the blowing agent were taken out and dehydrated and dried. afterwards,Example 1Classification, surface coating with additives, foaming, and molding in the same manner as described above.
[0054]
Example 4
(Manufacture of nuclei)
  Reference Example 8In the same manner, regenerated styrene resin particles having a weight average molecular weight of 169,000 and a specific gravity of 0.91 were obtained.
(Manufacture of recycled foam particles)
  A 5 liter pressure-resistant stirring vessel is charged with 1900 g of deionized water, 1100 g of the above regenerated styrene resin particles (core), 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate, and the temperature is raised to 75 ° C. while stirring. Warm up.
  Next, 400 g of deionized water and 1.3 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 200 g of styrene monomer in which 0.2 g of t-butyl peroxide and 2.9 g of benzoyl peroxide are dissolved is added. The mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 60 minutes, and then heated to 90 ° C.
  Thereafter, 900 g of styrene monomer was continuously added at a constant rate (3.0 g / min) over 5 hours. At this time, the inside of the pressure-resistant stirring vessel was purged with nitrogen to keep the oxygen concentration at 2 to 5% by volume. The styrene monomer content at this time was 15% (polymerization rate 85%).
  Subsequently, after adding 2.2 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Next, the mixture was cooled to 100 ° C., and 180 g of butane (i / n ratio = 4/6, the same as the weight ratio) 180 g as a blowing agent was injected in two portions and held for 10 hours to impregnate the blowing agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. afterwards,Example 1Classification, surface coating, pre-foaming, and molding were performed in the same manner as described above.
[0055]
Example 5
(Manufacture of recycled foam particles)
  1900 g of deionized water in a 5 liter pressure-resistant stirring vessel,Example 41100 g of the regenerated styrene resin particles (core) produced in 1), 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate were charged. Next, the inside of the pressure-resistant stirring vessel was purged with nitrogen to adjust the oxygen concentration to 2 to 5% by volume. Thereafter, the temperature was raised to 75 ° C. while stirring.
  Next, 400 g of deionized water and 1.3 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 200 g of styrene monomer in which 0.2 g of t-butyl peroxide and 2.9 g of benzoyl peroxide are dissolved is added. The mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 60 minutes, and then heated to 90 ° C.
  Thereafter, 900 g of styrene monomer was continuously added at a constant rate (3.0 g / min) over 5 hours. At this time, the inside of the pressure-resistant stirring vessel was purged with nitrogen to keep the oxygen concentration at 2 to 5% by volume. The styrene monomer content at this time was 13% (polymerization rate 87%).
  Subsequently, after adding 2.2 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Next, the mixture was cooled to 100 ° C., and 180 g of butane (i / n ratio = 4/6, the same as the weight ratio) 180 g as a blowing agent was injected in two portions and held for 10 hours to impregnate the blowing agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. afterwards,Example 1Classification, surface coating with additives, foaming, and molding in the same manner as described above.
[0056]
Example 6
(Manufacture of recycled foam particles)
  1900 g of deionized water in a 5 liter pressure-resistant stirring vessel,Example 41100 g of the regenerated styrene resin particles (core) produced in 1), 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate were charged. Next, the inside of the pressure-resistant stirring vessel was purged with nitrogen to adjust the oxygen concentration to 0.5 to 1% by volume. Thereafter, the temperature was raised to 75 ° C. while stirring.
  Next, 400 g of deionized water and 1.3 g of polyvinyl alcohol are mixed in a monomer dispersion container, and 200 g of styrene monomer in which 0.2 g of t-butyl peroxide and 2.9 g of benzoyl peroxide are dissolved is added. The mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container over 30 minutes, and then kept warm for 60 minutes, and then heated to 90 ° C.
  Thereafter, 900 g of styrene monomer was continuously added at a constant rate (3.0 g / min) over 5 hours. At this time, the inside of the pressure-resistant stirring vessel was purged with nitrogen to keep the oxygen concentration at 0.5 to 1% by volume. The styrene monomer content at this time was 10% (polymerization rate 90%).
  Subsequently, after adding 2.2 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Next, the mixture was cooled to 100 ° C., and 180 g of butane (i / n ratio = 4/6, the same as the weight ratio) 180 g as a blowing agent was injected in two portions and held for 10 hours to impregnate the blowing agent.
  After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. afterwards,Example 1Classification, surface coating with additives, foaming, and molding in the same manner as described above.
[0057]
Comparative Example 2
  As a comparison,Example 4In, except not performing nitrogen purge in the pressure-resistant stirring vessel,Example 4In the same manner as above, regenerated expandable styrene resin particles were obtained. At this time, the oxygen concentration was 17 to 20% by volume.
[0058]
Evaluation Example 3
  Example 1~Example 6, Comparative Examples 1 and 2The weight average molecular weight of the surface portion and the central portion was measured as follows.
  Regenerated foamable styrene resin particles were foamed in saturated water vapor to a bulk multiple of 50 ml / g.
  Arbitrary foam particles 2 to 3 were collected, and with a razor, the particles 1 were equally divided into 5 at half equal intervals to form portions 1, 2, 3, 4, and 5 from the outside. . The outermost part 1 (surface part) was taken out as it was, and the innermost part 5 (center part) was taken out by dividing the center into five parts with an injection needle, and the molecular weight was measured. For part 3 (3/5 part from the center), the same center as part 5 was pulled out with an injection needle, and the molecular weight was measured.
  In addition, the fusion rate was shown by the ratio of the broken bead and the unbroken bead in the fracture surface when the molded product was broken.
    Fusion rate (%)
    = Number of broken beads / (number of broken beads + number of unbroken beads)
  Example 1~Example 6, Comparative Examples 1 and 2Table 3 shows the evaluation results.
[0059]
[Table 3]

[0060]
  further,Example 6as well asComparative Example 2About the surface part of the reproduction | regeneration foamable styrene-type resin particle obtained by (1), the chart (GPC chart) by the gel permeation chromatograph (GPC) method was obtained. At that time, it measured with the following apparatuses and conditions.
    Measuring device: manufactured by Hitachi, Ltd.
    Eluent: THF, Flow rate: 2 ml / min
    Detector: UV 220nm
    Column: Hitachi Chemical Co., Ltd. GL-R400M 2
  Example 6as well asComparative Example 2The GPC charts are shown in FIGS. 3 (a) and 3 (b), respectively. As shown in these figures,Example 6The particles whose molecular weight suddenly increased like this had two peaks on the GPC chart. Two mountains are formed because of the high polymer ratio. on the other hand,Comparative Example 2The particles whose molecular weight increased little by little, such as a slight swelling on the GPC chart, had no inflection points, and neither shoulder nor two peaks were formed.
[0061]
[Effects of addition of inorganic substances and / or organic lubricants to the core]
Reference Example 11
(Manufacture of nuclei)
  A foamed styrenic resin molded product (molded product obtained from Hitachi Chemical Co., Ltd. High Beads SSB-HX) is shrunk with hot air at 220 ° C., apparent specific gravity 0.75, size 500 mm × 400 mm × 100 mm and weight A shrinkage of 15 kg was obtained. The shrinkage was roughly pulverized by a pulverizer (product of Horai Co., Ltd., ZA-560 type pulverizer) equipped with a 10 mm screen. The maximum length of the coarsely pulverized product obtained at this time was approximately 10 mm and the bulk specific gravity was 0.5.
  Next, 2000 g of this coarsely pulverized product and 20 g of talc (manufactured by Hayashi Kasei Co., Ltd., White Micron # 5000) having an average particle size of 10 μm and 0.6 g of ethylene bisstearylamide are added to a Henschel mixer (Mitsui Miike Chemical, FM10B). Mix for 2 minutes at 2000 rpm. The coarsely pulverized material surface-coated with talc and ethylenebisstearylamide is melted while pulling the sheet at approximately the same speed as the extrusion speed using a vented 30 mm extruder (T die, sheet width 300 mm, sheet pressure 1 mm). Extruded.
  Furthermore, before cooling and solidification, a slit having a 1 mm interval and a depth of 0.5 mm was provided by a roll horizontally with respect to the extrusion direction, and after cooling and solidification, it was cut into about 10 to 15 cm by a cutting machine. Subsequently, the obtained sheet-like styrene resin cut piece was finely pulverized by a pulverizer (VM-16 type pulverizer, Orient trade name, Inc.) equipped with a 2 mm screen. The finely pulverized product was classified with a sieve in a range of 0.6 to 1.0 mm to obtain regenerated styrene resin particles.
(Manufacture of recycled foam particles)
  A 5 liter pressure-resistant stirring vessel was charged with 1100 g of the regenerated styrene resin particles, 1500 g of deionized water, 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate, and the temperature was raised to 70 ° C. while stirring.
  Next, 350 g of deionized water and 0.36 g of polyvinyl alcohol were mixed in a monomer dispersion container, and 200 g of a styrene monomer in which 3.2 g of t-butyl peroxide was dissolved was added thereto. The styrene monomer was finely dispersed (average monomer oil droplet diameter of 10 to 100 μm) by stirring at 5800 rpm for 120 seconds using an industrial product. This styrene monomer dispersion was added to the container, kept warm for 90 minutes, and then heated to 90 ° C. Next, 600 g of styrene monomer was continuously added at a constant rate (3.3 g / min) over 3 hours.
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Next, the mixture was cooled to 100 ° C., butane (isobutane / n-butane weight ratio = 4/6) as a blowing agent was injected in 160 g portions in two portions, and held for 10 hours to impregnate the blowing agent.
  After cooling to room temperature, the expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried. Next, the resin particles were classified with a sieve having an opening of 1.70 mm and 0.60 mm to obtain 2240 g of resin particles. To the obtained resin particles, 1.12 g of zinc stearate and then 2.24 g of hardened castor oil were sequentially added and mixed.
  Next, the resin particles were classified with a sieve having an opening of 1.70 mm and 0.60 mm to obtain 2240 g of resin particles. To the obtained resin particles, 1.12 g of zinc stearate and then 2.24 g of hardened castor oil were sequentially added and mixed to obtain regenerated expandable styrene resin particles.
  The regenerated foamable styrene resin particles obtained were prefoamed to 50 ml / g and aged for about 18 hours, and then molded using a molding machine for foamed styrene resin (VS-300 manufactured by Daisen Industry) with a molding pressure of 0.08 MPa. To obtain a molded product.
[0062]
Reference Example 12
  Reference Example 11In the above, except that 40 g of talc and ethylene bisstearylamide are not used,Reference Example 11The same operations as described above were performed to obtain recycled foamable styrene resin particles and a molded product.
[0063]
Reference Example 13
  Reference Example 11Except that 1.0 g of ethylenebisstearylamide and talc are not used.Reference Example 11The same operations as described above were performed to obtain recycled foamable styrene resin particles and a molded product.
[0064]
Reference Example 14
  Reference Example 11Except that talc was calcium carbonate having an average particle size of 12 μm,Reference Example 11The same operations as described above were performed to obtain recycled foamable styrene resin particles and a molded product.
[0065]
Reference Example 15
  As a comparison,Reference Example 11Except that talc and ethylenebisstearylamide are not used.Reference Example 11The same operation as in Example 1 was performed to obtain recycled foamable styrene resin particles and a molded product.
[0066]
Evaluation Example 4
  Reference Example 11~Reference Example 15The cell diameter was measured by cutting the foamed particles with a sharp cutter knife or the like, taking a micrograph of the cross section, measuring the diameter of 10 cells from the obtained photograph, and taking the average as the cell diameter.
  Reference Example 11~Reference Example 15Table 4 shows the evaluation results.
[0067]
[Table 4]

[0068]
[Influence of particle size of core (recycled styrene resin particles)]
Reference Example 16
(Manufacture of nuclei)
  Reference example 1In the same manner as above, a finely pulverized product was obtained. The finely pulverized product was classified using a sieve having an opening of 1.40 mm and 0.85 mm to obtain regenerated styrene resin particles. The average particle diameter of the obtained regenerated styrene resin particles was 1170 μm, and the content of particles of 300 μm or less was 0.4% by weight.
(Manufacture of recycled foam particles)
  A 5 liter pressure-resistant stirring vessel was charged with 1100 g of the regenerated styrene resin particles, 1500 g of deionized water, 12.0 g of tricalcium phosphate, and 0.09 g of sodium dodecylbenzenesulfonate, and the temperature was raised to 70 ° C. while stirring.
  Next, 350 g of deionized water and 0.36 g of polyvinyl alcohol were added to the monomer dispersion container and mixed, and 300 g of styrene monomer in which 0.25 g of t-butylperoxy-2-ethylhexyl carbonate was dissolved was added. The mixture was stirred at 5800 rpm for 120 seconds using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container, and then kept warm for 30 minutes.
  Next, 300 g of deionized water and 0.24 g of polyvinyl alcohol are put in a monomer dispersion container and mixed, and 200 g of a styrene monomer in which 3.0 g of benzoyl peroxide is dissolved is added thereto. The styrene monomer was dispersed finely (average diameter of monomer oil droplets 10 to 100 μm) by stirring at 5800 rpm for 120 seconds using The styrene monomer dispersion was added to the container and kept warm for 90 minutes, and then heated to 90 ° C.
  Thereafter, 600 g of styrene monomer was continuously added at a constant rate (3.3 g / min) over 3 hours.
  Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 5 hours. Then, it is cooled to 100 ° C., butane (i / n ratio = 4/6, weight ratio, the same applies hereinafter) as a blowing agent is injected in 80 g portions in two portions, and held for 10 hours to impregnate the blowing agent. went. After cooling to room temperature, the styrene resin particles impregnated with the blowing agent were taken out and dehydrated and dried.
  Next, the resin particles were classified with a sieve having an aperture of 2.00 mm and 0.85 mm to obtain 2210 g of resin particles. To the obtained resin particles, 1.11 g of zinc stearate and then 1.11 g of hardened castor oil were sequentially added and mixed to obtain regenerated expandable styrene resin particles.
  The regenerated foamable styrene resin particles obtained were prefoamed to 50 ml / g and aged for about 18 hours, and then molded using a molding machine for foamed styrene resin (VS-300 manufactured by Daisen Industry) with a molding pressure of 0.08 MPa. To obtain a molded product.
[0069]
Reference Example 17
(Manufacture of nuclei)
  Reference Example 16A finely pulverized product of styrene resin was prepared by the same method as above, and classified using sieves having openings of 1.70 mm and 0.60 mm to obtain regenerated styrene resin particles. The obtained regenerated styrene resin particles had an average particle diameter of 1260 μm, and the content of particles of 300 μm or less was 0.6% by weight.
(Manufacture of recycled foam particles)
  Using the above regenerated styrene resin particlesReference Example 16The obtained resin particles were classified with a sieve having an opening of 2.20 mm and 0.60 mm to obtain 2160 g of resin particles. To the obtained resin particles, 1.80 g of zinc stearate and then 1.08 g of hardened castor oil were sequentially added and mixed to obtain regenerated expandable styrene resin particles.
  Using the obtained recycled foamable styrene resin particles,Reference Example 16In the same manner as above, preliminary foaming and molding were performed to obtain a molded product.
[0070]
Reference Example 18
(Manufacture of nuclei)
  Reference Example 16A finely pulverized product of styrene resin was prepared in the same manner as described above, and classified using sieves with openings of 1.40 mm and 0.43 mm, to obtain regenerated styrene resin particles. The obtained regenerated styrene resin particles had an average particle size of 1060 μm, and the content of particles of 300 μm or less was 2.4% by weight.
(Manufacture of recycled foam particles)
  Using the above regenerated styrene resin particlesReference Example 16The obtained resin particles were classified with a sieve having an opening of 1.70 mm and 0.50 mm to obtain 2110 g of resin particles. To the obtained resin particles, 1.60 g of zinc stearate and then 1.06 g of hardened castor oil were sequentially added and mixed to obtain regenerated expandable styrene resin particles.
  Using the obtained recycled foamable styrene resin particles,Reference Example 16In the same manner as above, preliminary foaming and molding were performed to obtain a molded product.
[0071]
Evaluation Example 5
  Reference Example 16~Reference Example 18The average particle size was measured as follows.
(1) JIS standard sieves (JIS Z 8801) were arranged so as to overlap in the following order of openings (unit: mm) (however, a plate was added at the bottom).
2.00, 1.70, 1.40, 1.18, 1.00, 0.85, 0.71, 0.60, 0.50, 0.425, 0.355, 0.30 in order from the top. 0.25
(2) 100 g of a sample was weighed and placed on the top of the sieve.
(3) The sample was sieved in order from the top until the sample no longer dropped from the sieve. The sample dropped from the sieve was added to the next stage sieve. This operation was repeated to the lowest level.
(4) The weight of the sample remaining on each sieve was measured.
(5) The particle size distribution for each sieve was determined by the following equation.
[Expression 1]

(6) The cumulative value of the particle size distribution was determined in order from the sieve with the larger opening.
(7) The data obtained in (6) was plotted with the horizontal axis as the particle size (= sieve opening) and the vertical axis as the cumulative value of the particle size distribution. Next, the plotted points were connected to form a smooth curve.
(8) From the above curve, the particle size when the cumulative value was 50 (%) was read. The read value was taken as the average particle size of this sample.
  Reference Example 16~Reference Example 18Table 5 shows the evaluation results.
[0072]
[Table 5]

[0073]
[Industrial applicability]
  ADVANTAGE OF THE INVENTION According to this invention, the reproduction | regeneration foamable styrene-type resin particle and reproduction | regeneration styrene-type foaming molding which are excellent in the external appearance and / or intensity | strength of a molded article can be provided.
[0074]
[Brief description of the drawings]
  FIG. 1 shows the present invention.InIt is a figure for demonstrating the measuring method of a surface layer part and this molecular weight.
  FIG. 2 shows the present invention.InIt is a figure for demonstrating the measuring method of these molecular weights, a surface part and a center part.
  Figure 3Example 6as well asComparative Example 2It is a GPC chart.

Claims (12)

Suspended regenerated styrene resin particles in an aqueous medium as a core,
A polymerization initiator and a styrene monomer are added to this suspension, impregnated into regenerated styrene resin particles, polymerization is performed, and the content of styrene monomer in the suspension (however, added) When the styrene monomer is completely polymerized, the content is 0% by weight.) When the content is 20% by weight or less, the oxygen concentration in the reaction vessel is kept at 7% by volume or less and the polymerization reaction proceeds. ,
A method for producing regenerated expandable styrene resin particles, wherein a foaming agent is impregnated into resin particles during or after polymerization.   The method for producing regenerated foamable styrene resin particles according to claim 1, wherein the polymerization initiator is dissolved in a styrene monomer and the regenerated styrene resin particles are impregnated.   The method for producing regenerated expandable styrene resin particles according to claim 1 or 2, wherein a flame retardant is impregnated together with the foaming agent.   The method for producing regenerated expandable styrene resin particles according to claim 1, wherein the oxygen concentration in the reaction vessel is kept at 1% by volume or less from the start of polymerization until the content of the styrene monomer is 20% or less.   The method for producing regenerated expandable styrene resin particles according to any one of claims 1 to 4, wherein the regenerated styrene resin particles have a weight average molecular weight of 100,000 to 250,000.   The method for producing regenerated expandable styrene resin particles according to any one of claims 1 to 5, wherein the regenerated styrene resin particles include a fine powdery inorganic substance and / or an organic lubricant.   The regenerated foamable styrene resin according to any one of claims 1 to 6, wherein the regenerated styrene resin particles have an average particle diameter of 500 µm or more and less than 2000 µm and a content of particles of 300 µm or less is less than 1 wt%. Particle manufacturing method.   The method for producing regenerated expandable styrene resin particles according to any one of claims 1 to 7, wherein the regenerated styrene resin particles have a colored styrene resin removed. A core composed of regenerated styrene resin particles ;
Wherein a core is expandable styrene resin particles ing from virgin styrene resin containing the,
The virtual line segment from the particle surface to the particle center 5 equal portions, and among the five cutting portions obtained by cutting the resin particles so as to be perpendicular to the virtual line, the cut portion of the most superficial side weight average molecular weight, most central part of the cut portion of the center side (however, the central portion of the diameter 5 equally divided portions of the cut surface of the resin particle center side in the cutting portion of the most central side central portion From the weight average molecular weight of a cylindrical portion having a length of one-fifth of the diameter of the cut surface on the resin particle center side obtained by drawing out in a circle in the imaginary line segment direction). More than 50,000 recycled foamable styrene resin particles.   The regenerated expandable styrene resin particles according to claim 9, wherein a ratio of the regenerated styrene resin particles is 30% by weight to 70% by weight with respect to the regenerated expandable styrene resin particles.   Regenerated styrene foam beads obtained by foaming the regenerated expandable styrene resin particles according to claim 9 or 10.   A regenerated styrene foam-molded product obtained by molding the regenerated styrene foam beads according to claim 11.

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