JP3600325B2

JP3600325B2 - Method for producing rubber-reinforced styrenic resin

Info

Publication number: JP3600325B2
Application number: JP23361995A
Authority: JP
Inventors: 和彦正; 敏晴川崎
Original assignee: Asahi Kasei Chemicals Corp
Current assignee: Asahi Kasei Chemicals Corp
Priority date: 1995-09-12
Filing date: 1995-09-12
Publication date: 2004-12-15
Anticipated expiration: 2015-09-12
Also published as: JPH0977834A

Description

【０００１】
【発明の属する技術分野】
本発明は、粒子状に分散したゴム状弾性体粒子の大きさを制御する方法であり、更には、衝撃強度、外観特性等に優れ、かつ、高い生産性を有するゴム補強スチレン系樹脂の製造方法を提供するものである。
【０００２】
【従来の技術】
ゴム補強スチレン系樹脂の製造は比較的古く、そして当該業者にとって現状の工業的方法は明らかに周知である。代表的な技術によれば、単量体の中に溶解されたゴム溶液を最初の段階の反応機内で機械的撹拌下で重合させる。
重合がバッチ式、又は連続式の撹拌されたプラグフロー反応機内で起ころうか、又は連続式の撹拌されたタンク反応機内で起ころうかであるが、殆ど全ての従来の技術及び開示は最終生成物中に分散されたゴム状弾性体に関する粒子径、粒子径分布はプロセスの早い時点で大部分決定されてしまうと明示している。
【０００３】
重合がバッチ式、又は連続式の撹拌されたプラグフロー反応機内で進行すると、単量体の転化率が５〜２０％の或る時点において、機械的撹拌による剪断で、ゴム状弾性体が分散相に、ポリスチレン系樹脂相が連続相になる。即ち、相転換が生じ、ゴム粒子が形成される。この相転換は瞬時に起こるわけではなく、かなりの時間、空間にわたって生じる。代表的には、２０〜５０分間にわたって、又は２〜８％の単量体転化率を生じる反応機空間にわたって生じる。それ故、ゴム粒子径、ゴム粒子径分布を正確に制御することには困難が伴う。また、連続式の完全混合型反応機の場合は、ゴム粒子形成は瞬時に生じるが、反応系の動的挙動に起因する滞留時間分布、反応系の各単位容量に同じ剪断履歴を確実に与えることは不可能ではないにしても非常に困難である為、結果として、分散されたゴム粒子径分布は一般的最も広くなる。
【０００４】
ゴム補強スチレン系樹脂の物性は分散されたゴム状弾性体の粒子径、粒子径分布に大きく依存している。ゴム粒子径、粒子径分布の正確な制御がゴム補強スチレン系樹脂の物性を制御する重要な因子であることは公知の事実である。
又、プラグフロー反応機、完全混合型反応機等は単位体積当たりの伝熱面積が小さいため、反応熱の除熱能力が小さく、その結果、生産性の向上が期待できない。又、単量体の転化率が高くなると、高粘度溶液の撹拌による熱が生じ、除熱する熱量が増え．結果、生産性の低下を招くという欠点も有している。
【０００５】
上述の撹拌されたプラグフロー反応機、完全混合型反応機の欠点を解消する為に、静的混合器を内蔵した管状反応器で構成された環状反応器で相転換を行わせ、ゴム粒子を形成する方法が提案されている（特公平７−２５８５６号公報）。しかし、この方法では、ゴム粒子形成に必要な剪断力は環状反応器内を流れる反応溶液粘度、流速に依存しており、比較的大きいゴム粒子径は製造しやすいが、比較的小さいゴム粒子径を得るには、還流速度を速めなければならず、環状反応器内の圧力損失が大きくなるため困難を伴う。この方法の欠点を解消する為に、環状反応器を構成する管状反応器の中間に動的インラインミキサーを導入する方法が提案されている（特公平７−２５８５７号公報）。
【０００６】
この方法では、一度相転換したゴム粒子を更に強い剪断力で小さくする為、ゴム粒子の破壊が生じ、又、ゴム状弾性体の分子鎖切断等が生じ、その結果、物性低下に繋がり好ましくない。又、特公平７−２５８５６号公報、特公平７−２５８５７号公報で開示されている管状型反応器では、反応熱の交換はジャケット部の伝熱のみであり、プラグフロー反応機と同じ程度にしか除熱できず、生産性の向上は期待できない。
【０００７】
【発明が解決しようとする課題】
大ゴム粒子径から小ゴム粒子径まで広いゴム粒子径範囲でのゴム粒子径制御が容易になるゴム補強スチレン系樹脂の製造方法を提供するもので、この製造方法により、強度、外観等に優れ、かつ生産性に優れたゴム補強スチレン系樹脂が得られる。
【０００８】
【課題を解決するための手段】
すなわち、本発明は、熱媒体が通る流路を有する静的混合器を内蔵した管状反応器と撹拌翼を備えた反応機と反応液を移送するポンプとからなる環状反応器（Ｉ）と熱媒体が通る流路を有する静的混合器を内蔵した管状反応器（II）とからなり、スチレン系モノマーおよびゴム状重合体を含む原材料溶液を撹拌翼を備えた反応機に供給し、環状反応器（Ｉ）を一部循環しつつ、管状反応器（II）に供給する重合方法であって、環状反応器（Ｉ）を構成する管状反応器と撹拌翼を備えた反応機の体積比が５／１〜２０／１であり、環状反応器（Ｉ）と管状反応器（II）の体積比が１／１〜１／５である重合装置であり、管状反応器（II）に少なくとも１か所以上から有機過酸化物溶液を供給するもので、反応器（Ｉ）中の撹拌翼を備えた反応機のポリマー濃度が原材料中のゴム状弾性体濃度の２〜１０倍になるように制御することを特徴とする、連続したスチレン系樹脂相中にゴム状弾性体が粒子状に分散したゴム補強スチレン系樹脂の製造方法である。
【０００９】
環状反応器（Ｉ）を構成する熱媒体が通る流路を有する静的混合器を内蔵してなる管状反応器としては、熱媒体が通過できる構造を有した静的混合構造部が内部に固定されたものである。単位体積当たりの伝熱面積（Ａ／Ｖ）の値は、３０（ｍ^２／ｍ^３）以上が好ましい。管状反応機のジャケット部は必ずしも必要ではない。かかる管状反応器としては、スルザー社のＳＭＲ反応器が好適に用いることができる。
【００１０】
環状反応器を構成する撹拌翼を備えた反応機としては、一般的に使用されている撹拌翼を備えた完全混合型反応機、あるいは撹拌翼を備えた塔型反応機（プラグフロー反応機）、回転円筒型反応機等が使用できる。中でも、撹拌翼を備えた塔型反応機、回転円筒型反応機が好適に用いることができる。
熱媒体が通る流路を有する静的混合器を内蔵してなる管状反応器（ＩＩ）としては、熱媒体が通過できる構造を有した静的混合構造部が内部に固定されたものである。単位体積当たりの伝熱面積の値は、３０（ｍ^２／ｍ^３）以上が好ましい。管状反応機のジャケット部は必ずしも必要ではない。かかる管状反応器としては、図１に示す概略図のような管状反応器であり、具体的には、スルザー社のＳＭＲ反応器が好適例に用いることができる。
【００１１】
原材料溶液は撹拌翼を備えた反応機に供給する必要がある。原材料溶液と環状反応器を循環している重合溶液との混合性がゴム粒子径を決める最大の因子である。低粘度液を高粘度液中に短時間で分散する必要がある。原材料溶液が環状反応器中の管状反応器中に供給されると、静的混合器の剪断力が弱い為に分散に長時間かかり、その間にゴム粒子が形成され、結果的にゴム粒子径が大きく、比較的広い粒子径分布のものしか得られない。原材料溶液と重合溶液が撹拌翼を備えた反応機内で短時間で混合される時、原材料溶液と重合溶液の混合度合いに応じて、弱い剪断力を与える静的混合器を有する管状反応器内で粒子径分布の狭い大粒子から小粒子までのゴム粒子径を形成する。原材料溶液と重合溶液の混合度合いは、撹拌翼を備えた反応機の撹拌数によっても制御できるが、撹拌数を高めるとゴム状弾性体、還流された重合溶液中のゴム粒子に大きな剪断力を与え、ゴム状弾性体の切断、ゴム粒子の破壊が生じ好ましくない。原材料溶液と還流された重合溶液の粘度差を利用して分散度合いを制御することが好ましい。混合度合いを高めるには二つの溶液の粘度差を小さくし、混合度合いを低めるには二つの溶液の粘度差を高めることにより達成される。その為に、撹拌翼を備えた反応機内のポリマー濃度（ゴム状弾性体と単量体から生成したスチレン系樹脂の総和の重量濃度）が原材料中のゴム状弾性体濃度（重量濃度）の２〜１０倍になるように制御する必要がある。２倍以下の場合は、還流された重合溶液中のゴム粒子が解体され（解相転）、ゴム状弾性体が疑似連続相的形態を示し、ゴム粒子径の制御が非常に困難になる。１０倍を越える場合は、原材料溶液と重合溶液の混合が困難になり、ゴム粒子径制御が困難になる。この時、撹拌翼を備えた反応機の撹拌数はゴム状弾性体の切断、ゴム粒子の破壊が生じない程度で制御する必要がある。
【００１２】
環状反応器を構成する管状反応器と撹拌翼を備えた反応機の体積比は５／１〜２０／１である。この比が５／１より小さい場合は、撹拌翼を備えた反応機内での滞留時間が長くなり、滞留時間分布に起因する粒子径分布の広がり、ゴム粒子の肥大化等が生じゴム粒子径制御が困難になる。又、この比が大きい場合は原材料溶液と重合溶液の混合度合いの制御が困難となり、その結果、ゴム粒子径制御が困難になる。
【００１３】
有機過酸化物溶液を管状反応器（ＩＩ）の任意の所に１か所以上供給する必要がある。単量体転化率が高くなると、反応速度が遅くなり、生産性の低下に繋がる。又、環状反応器で形成されたゴム粒子は表面にポリスチレンがグラフトされていないか、されていても不十分である。強度、外観特性等高めるために管状反応器（ＩＩ）でポリスチレンをグラフトさせる必要がある。これらの目的達成のためには、有機過酸化物溶液を供給し、反応速度を早め、グラフト反応を促進することが必要である。有機過酸化物溶液の供給部位は１か所以上が好ましい。有機過酸化物溶液の供給部位は特に制約はないが、１か所の場合は、管状反応器（ＩＩ）の入口、２か所の場合は管状反応器（ＩＩ）の入口部と中央部が好ましい。３か所以上の場合は、管状反応器（ＩＩ）を等分割した部位に供給することが好ましい。有機過酸化物溶液は有機過酸化物単独あるいはエチルベンゼン等溶媒に希釈して供給してもよい。使用される有機過酸化物も特に制約はないが、１０時間半減期温度が９０〜１４０℃、例えば、日本油脂株式会社のパーヘキサＣ、パーヘキサ３Ｍ、パーブチルＺ、パーブチルＤ、パーヘキサ２５Ｂ、パーブチルＩ等が好適に用いられる。
【００１４】
環状反応器（Ｉ）と管状反応器（ＩＩ）の体積比は１／１〜１／５である。好ましくは、１／１〜１／３である。この比が１／１より大きい場合、環状反応器（Ｉ）はゴム粒子径制御の観点からある程度反応速度に制約があり、管状反応器（ＩＩ）での生産性向上の為の負荷が大きくなり、品質と生産性のバランスが悪くなる。この比が１／３より小さい場合、単位体積当たりの生産性が悪くなる。本発明で言う生産性とは、単位体積当たり、単位時間当たりの生産量を言う。従来の製造プロセス、製造条件では１〜２トン／ｍ^３／日であるが、本発明で言う高生産性とは３〜５トン／ｍ^３／日で程度の値を意味する。
【００１５】
本発明で言うゴム補強スチレン系樹脂とは、連続相がスチレン、α−メチルスチレン等からなるポリマー、あるいはスチレン、α−メチルスチレンと共重合可能な単量体、（メタ）アクリル酸エステル、例えばブチルアクリレート、メチルメタクリレート、ブチルメタクリレート、メチルアクリレート等、及びアクリロニトリル等の共重合体であり、分散相がポリブタジエン、スチレン・ブタジエン共重合体、スチレン・ブタジエンブロック共重合体、エチレン・プロピレンターポリマー等のゴム状弾性体によって形成されたゴム粒子から構成されている樹脂である。
【００１６】
本発明でいう原料溶液としては、単量体にゴム状弾性体を溶解した溶液であり、必要に応じてエチルベンゼン、トルエン等の重合溶媒、分子量調整剤、１０時間半減期温度が９０〜１４０℃、例えば日本油脂株式会社のパーヘキサＣ、パーヘキサ３Ｍ、パーブチルＺ、パーブチルＤ、パーヘキサ２５Ｂ、パーブチルＩ等の重合開始剤、ミネラルオイル、シリコーンオイル等の可塑剤、酸化防止剤等を原材料溶液に添加してもよい。
【００１７】
原材料溶液は撹拌翼を備えた反応機に供給されるが、撹拌翼を備えた反応機に供給される前の段階で予備重合等の前処理を行ってもよい。但し、ゴム状弾性体がゴム粒子を形成しない転化率に押さえることが肝要である。
環状反応器（Ｉ）の重合温度は、１００〜１５０℃の範囲が好適に用いられる。環状反応器の循環量も特に制約はないが、用いる静的混合器が混合能力を十二分に発揮できる最低流速以上で使用する必要がある。
【００１８】
例えばスルーザー社のＳＭＲ反応機の場合、２ｍ／ｈ以上の流速が得られる循環量で循環することが好ましい。循環比（循環流量／原材料溶液供給流量）は２〜１５が好適に用いられる。循環比を変化させることによりゴム粒子径を制御することも可能であるが、制御できる自由度は小さい。しかし、圧力損失等を考慮しつつ循環量でゴム粒子径の微調整を行うことはなんら問題はない。
【００１９】
管状反応器（ＩＩ）での重合温度は、１２０〜１８０℃の範囲が好適に用いられる。そして、管状反応器（ＩＩ）の出口の固形分（連続相と分散相のポリマーの総和）濃度は７０重量％以上、好ましくは８０重量％以上になるように重合条件を設定することが好ましい。固形分濃度が低いと、高生産性を維持するために、回収能力の負荷が大きくなり好ましくない。
【００２０】
管状反応器（ＩＩ）から出た重合溶液は回収設備に送られ、未反応単量体、重合溶媒等を除去されペレット化される。回収系に入る前、又は回収系を出た後にゴム補強スチレン系樹脂に多用されている添加剤、例えば、酸化防止剤、可塑剤、着色剤、帯電防止剤、難燃剤等を添加することができる。
【００２１】
【発明の実施の形態】
物性等の測定方法は以下の方法による。
ＳＯＬＩＤ％：重合溶液約５ｇを精秤し、約５ｃｃのメタノールを加えた後、２００℃、１０ｍｍＨｇの条件下の真空乾燥機で２０分加熱後精秤し、固形分濃度（重量％）を計算する。
【００２２】
ゴム粒子径、粒子径分布：ＣｏｕｌｔｅｒＣｏｐｏｒａｔｉｏｎ社の下記の型式のコールターカウンターを用いて測定する。
本体：ＭＵＬＴＩＳＩＺＥＲＩＩ型、測定機：ＭＵＬＴＩＳＩＺＥＲＩＩＥ型、ジメチルホルムアミドとチオシアン酸アンモニウムからなる電解液を使用し、体積平均と数平均の５０％メジアン径を求める。本発明で言うゴム粒子径とは体積平均５０％メジアン径を、ゴム粒子径分布とは、体積平均５０％メジアン径と数平均５０％メジアン径の比を意味する。
【００２３】
アイゾット衝撃強度：ＡＳＴＭＤ６３８Ｉ準拠して測定した。
外観：成型温度２２０度、金型温度６０度の条件で、ダンベル試験片を成形し、ケート側から４ｃｍの所をＪＩＳＺ８７４１に準拠して測定した。
図１は、本発明の方法の実施に用いた装置の概略のフローシートである。タンク（１）内で調合された原料溶液はポンプ（２）で反応機（３）に送られる。反応機（３）はＬ／Ｄ＝１０、１５段の棒状羽根を有し、容積０．６Ｌのプラグフロータイプの反応機である。反応機（３）を出た重合溶液は反応器（４）に送らる。反応器（４）はスルーザー社のＳＭＲタイプの、内部に熱媒体が通る流路を有する静的混合器を内臓した管状反応器である。容積は６Ｌである。反応器（４）を出た重合溶液の一部はポプ（５）で反応機（３）に循環される。残りの重合溶液は反応器（６）に送られる。反応器（６）は反応器（４）と同じ構造を有し、容積は１２Ｌである。反応器（６）の入口部、中間部に開始剤溶液がポンプ（７）、（８）で追添できる。反応器（６）を出た重合溶液は二段ベント付二軸押出機（９）に送られ、未反応単量体、重合溶媒等を除去した後、ペレット化される。
【００２４】
【実施例１】
スチレン８１．５重量％、エチルベンゼン１２重量％、ゴム（旭化成工業株式会社製、アサプレン７３０Ａ）６．５重量％、有機過酸化物（日本油脂株式会社製、パーヘキサＣ）３００ｐｐｍ、α−メチルスチレンダイマー２００ｐｐｍになるようにタンク（１）で調合し、原料溶液を作製する。
【００２５】
原料溶液を３．５Ｌ／Ｈの速度で反応機（３）に供給する。反応機（３）、反応器（４）は１２３℃に制御する。反応機（３）の回転数は１００ｒｐｍ、循環比（循環流量／原料溶液流量）は１０で制御する。反応器（４）を出た重合溶液は反応器（６）に送られ、反応器（６）は前段を１４５℃、後段を１６０℃に制御する。ポンプ（７）を用いて、重合溶液に対して３００ｐｐｍの有機過酸化物（パーヘキサＣの５０重量％エチルベンゼン溶液）を追添する。
【００２６】
反応器（６）を出た重合溶液は二段ベント付二軸押出機（９）に送られ、２４０℃の温度で処理され、ペレット化される。結果を表１に示す。
【００２７】
【実施例２】
反応機（３）の撹拌数が１８０ｒｐｍ以外、実施例１と同様にして、ペレットを得る。結果を表１に示す。
【００２８】
【実施例３】
反応機（３）、反応器（４）が１１４℃に、反応器（６）の前段が１５０℃、後段が１７０℃に制御される以外、実施例１と同様にして、ペレットを得る。結果を表１に示す。
【００２９】
【実施例４】
反応機（３）の撹拌数が１８０ｒｐｍ以外、実施例３と同様にして、ペレットを得る。結果を表１に示す。
【００３０】
【実施例５】
反応機（３）、反応器（４）が１１９℃に、反応器（６）の前段が１４７℃、後段が１６５℃に制御される以外、実施例１と同様にして、ペレットを得る。結果を表１に示す。
【００３１】
【比較例１】
図１に於いて、反応機（３）を除き、原料溶液、ポンプ（５）で循環される重合溶液を直接反応器（４）に供給する以外、実施例１と同様にして、ペレットを得る。結果を表１に示す。
【００３２】
【比較例２】
循環比が１５以外、比較例１と同様にして、ペレットを得る。結果を表１に示す。
【００３３】
【比較例３】
反応器（４）の温度が１１４℃以外、比較例１と同様にして、ペレットを得る。結果を表１に示す。
【００３４】
【比較例４】
ポンプ（７）を用いて有機過酸化物を追添しない以外、実施例１と同様にして、ペレットを得る。結果を表１に示す。
【００３５】
【比較例５】
ポンプ（７）を用いて有機過酸化物を追添しない以外、実施例３と同様にして、ペレットを得る。結果を表１に示す。
【００３６】
【表１】

【００３７】
【実施例６】
図１の反応器（６）の容量が９Ｌであり、ポンプ（８）で２００ｐｐｍの有機過酸化物（日本油脂株式会社製、パーブチルＤの５０重量％エチルベンゼン溶液）を追添し、反応器（６）後段（容積３Ｌ）を１６５℃に制御する以外、実施例−１と同様にしてペレットを得る。ポンプ（８）で追添する位置は反応器（６）の入口部から２／３の位置である。反応器（６）を出た重合溶液のＳＯＬＩＤ％は８６％である。結果を表２に示す。
【００３８】
【比較例６】
反応機（３）と相似の構造を有し、容積が６Ｌの反応機を直列に３基配置し、実施例１と同じ組成の原料溶液を２．５Ｌ／Ｈで供給し、一段目の反応機の温度を１２０℃−１２５℃、二段目の反応機の温度を１３５℃−１４５℃、三段目の温度を１５５℃−１６５℃に制御し、得られた重合溶液は二段ベント付二軸押出機（９）に送られ、２４０℃の温度で処理され、ペレット化される。三段目反応機を出た重合溶液のＳＯＬＩＤ％は７３％である。結果を表２に示す。
【００３９】
【表２】

【００４０】
【比較例７】
比較例６と同じ装置を用い、実施例１と同じ組成の原料溶液を３．５Ｌ／Ｈで供給し、二段反応機の温度を１３５〜１５０℃、三段反応機の温度を１５０〜１７０℃の範囲で制御しつつ、三段目反応機を出た重合溶液のＳＯＬＩＤ％が７５％前後になるように運転したが、暴走的反応、失速的反応を繰り返し安定な運転は出来なかった。このプロセスでは高生産性は達成出来なかった。
【００４１】
【発明の効果】
本発明のゴム補強スチレン系樹脂の製造方法を用いることにより、大ゴム粒子径から小ゴム粒子径まで広いゴム粒子径範囲でのゴム粒子径制御が容易になる。そして、強度、外観等に優れ、かつ生産性に優れたゴム補強スチレン系樹脂が得られる。
【図面の簡単な説明】
【図１】管状反応器の一例を示す概略図である。
【図２】本発明の方法の実施に用いた装置の概略のフローシートである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a method for controlling the size of rubber-like elastic particles dispersed in a particle form, and furthermore, producing a rubber-reinforced styrene-based resin having excellent impact strength, appearance characteristics, and the like, and having high productivity. It provides a method.
[0002]
[Prior art]
The production of rubber reinforced styrenic resins is relatively old, and the state of the art industrial processes are clearly well known to those skilled in the art. According to a typical technique, a rubber solution dissolved in monomers is polymerized in a first stage reactor under mechanical stirring.
Whether the polymerization will take place in a batch or continuous stirred plug flow reactor or in a continuous stirred tank reactor, almost all conventional techniques and disclosures are for final production. It states that the particle size and particle size distribution of the rubber-like elastic material dispersed in the material are largely determined early in the process.
[0003]
As the polymerization proceeds in a batch or continuous stirred plug flow reactor, at some point where the monomer conversion is 5-20%, the rubbery elastomer is dispersed by mechanical shearing. The polystyrene resin phase becomes a continuous phase. That is, a phase change occurs and rubber particles are formed. This phase change does not occur instantaneously, but rather over time and space. It typically occurs over 20 to 50 minutes, or over the reactor space resulting in 2 to 8% monomer conversion. Therefore, it is difficult to accurately control the rubber particle diameter and the rubber particle diameter distribution. In the case of a continuous complete mixing type reactor, the formation of rubber particles occurs instantaneously, but the residence time distribution resulting from the dynamic behavior of the reaction system and the same shear history are reliably given to each unit volume of the reaction system. As a result, it is very difficult, if not impossible, so that the dispersed rubber particle size distribution is generally the broadest.
[0004]
The physical properties of the rubber-reinforced styrenic resin greatly depend on the particle size and particle size distribution of the dispersed rubber-like elastic material. It is a known fact that accurate control of the rubber particle diameter and particle diameter distribution is an important factor for controlling the physical properties of the rubber-reinforced styrenic resin.
Further, since the heat transfer area per unit volume of a plug flow reactor, a complete mixing type reactor, and the like is small, the ability to remove reaction heat is small, and as a result, improvement in productivity cannot be expected. Also, when the conversion of the monomer increases, heat is generated by stirring the high-viscosity solution, and the amount of heat to be removed increases. As a result, there is a disadvantage that productivity is reduced.
[0005]
In order to eliminate the drawbacks of the above-described stirred plug flow reactor and complete mixing type reactor, a phase change is performed in an annular reactor composed of a tubular reactor having a built-in static mixer, and rubber particles are removed. A forming method has been proposed (Japanese Patent Publication No. 7-25856). However, in this method, the shear force required for rubber particle formation depends on the viscosity and flow rate of the reaction solution flowing in the annular reactor, and a relatively large rubber particle diameter is easy to produce, but a relatively small rubber particle diameter. In order to obtain, the reflux rate must be increased, which is accompanied by difficulty due to a large pressure loss in the annular reactor. In order to solve the drawback of this method, there has been proposed a method of introducing a dynamic in-line mixer in the middle of a tubular reactor constituting a circular reactor (Japanese Patent Publication No. 7-25857).
[0006]
In this method, the rubber particles that have undergone phase inversion are further reduced by a stronger shear force, so that the rubber particles are broken, and the molecular chains of the rubber-like elastic body are cut off, and as a result, the physical properties are reduced, which is not preferable. . In the tubular reactors disclosed in Japanese Patent Publication Nos. 7-25856 and 7-25857, the reaction heat is exchanged only through the heat transfer in the jacket portion, and to the same extent as in the plug flow reactor. Only heat can be removed, and no improvement in productivity can be expected.
[0007]
[Problems to be solved by the invention]
A method for producing a rubber-reinforced styrenic resin that facilitates rubber particle diameter control in a wide rubber particle diameter range from a large rubber particle diameter to a small rubber particle diameter. The production method has excellent strength and appearance. In addition, a rubber-reinforced styrene resin having excellent productivity can be obtained.
[0008]
[Means for Solving the Problems]
That is, the present invention relates to an annular reactor (I) comprising a tubular reactor having a built-in static mixer having a flow path through which a heat medium passes, a reactor having a stirring blade, and a pump for transferring a reaction solution, and A tubular reactor (II) having a built-in static mixer having a flow path through which a medium flows, and supplying a raw material solution containing a styrene-based monomer and a rubber-like polymer to a reactor equipped with stirring blades to form a cyclic reaction; This is a polymerization method in which a tubular reactor (II) is supplied to a tubular reactor (II) while partially circulating the reactor (I). 5/1 to 20/1, wherein the volume ratio between the annular reactor (I) and the tubular reactor (II) is 1/1 to 1/5, wherein at least one polymerization reactor is provided in the tubular reactor (II). The organic peroxide solution is supplied from more than one place, and the reactor is provided with a stirring blade in the reactor (I). A rubber-reinforced styrene-based styrene resin in which a rubber-like elastic material is dispersed in a continuous styrene-based resin phase, wherein the limmer concentration is controlled to be 2 to 10 times the rubber-like elastic material concentration in the raw material. This is a method for producing a resin.
[0009]
As the tubular reactor having a built-in static mixer having a flow path through which the heat medium constituting the annular reactor (I) passes, a static mixing structure having a structure through which the heat medium can pass is fixed inside. It was done. The value of the heat transfer area (A / V) per unit volume is preferably 30 (m ² / m ³ ) or more. The jacket of the tubular reactor is not necessary. As such a tubular reactor, an SMR reactor manufactured by Sulzer can be suitably used.
[0010]
As a reactor having a stirring blade constituting a ring reactor, a generally used complete mixing reactor having a stirring blade or a tower reactor having a stirring blade (a plug flow reactor) And a rotating cylindrical reactor. Among them, a tower type reactor equipped with a stirring blade and a rotating cylindrical type reactor can be suitably used.
The tubular reactor (II) having a built-in static mixer having a flow path through which a heat medium passes has a static mixing structure having a structure through which the heat medium can pass, which is fixed inside. The value of the heat transfer area per unit volume is preferably 30 (m ² / m ³ ) or more. The jacket of the tubular reactor is not necessary. Such a tubular reactor is a tubular reactor as shown in the schematic diagram of FIG. 1, and more specifically, an SMR reactor manufactured by Sulzer can be used as a preferred example.
[0011]
The raw material solution needs to be supplied to a reactor equipped with a stirring blade. Mixability of the raw material solution and the polymerization solution circulating in the annular reactor is the largest factor that determines the rubber particle size. It is necessary to disperse a low viscosity liquid in a high viscosity liquid in a short time. When the raw material solution is fed into the tubular reactor in the annular reactor, the dispersion takes a long time due to the low shear force of the static mixer, during which rubber particles are formed, and as a result, the rubber particle diameter is reduced. Only a large, relatively wide particle size distribution can be obtained. When the raw material solution and the polymerization solution are mixed in a short time in a reactor equipped with a stirring blade, in a tubular reactor having a static mixer that applies a low shear force according to the degree of mixing of the raw material solution and the polymerization solution. A rubber particle diameter ranging from large particles to small particles having a narrow particle diameter distribution is formed. The degree of mixing of the raw material solution and the polymerization solution can also be controlled by the number of agitation of a reactor equipped with a stirring blade, but when the number of agitation is increased, a large shear force is applied to the rubber-like elastic body and the rubber particles in the refluxed polymerization solution. In addition, cutting of the rubber-like elastic body and destruction of rubber particles may occur, which is not preferable. It is preferable to control the degree of dispersion by utilizing the difference in viscosity between the raw material solution and the refluxed polymerization solution. The degree of mixing is achieved by reducing the difference in viscosity between the two solutions, and the degree of mixing is reduced by increasing the difference in viscosity between the two solutions. For this purpose, the polymer concentration (weight concentration of the sum of the styrene resin formed from the rubber-like elastic body and the monomer) in the reactor equipped with the stirring blade is 2% of the rubber-like elastic body concentration (weight concentration) in the raw material. It is necessary to control so as to be 10 to 10 times. If the ratio is less than twice, the rubber particles in the refluxed polymerization solution are disassembled (phase inversion), and the rubber-like elastic body exhibits a pseudo-continuous phase form, which makes it very difficult to control the rubber particle diameter. If it exceeds 10 times, it becomes difficult to mix the raw material solution and the polymerization solution, and it becomes difficult to control the rubber particle diameter. At this time, it is necessary to control the number of agitation of the reactor equipped with the agitating blade to such an extent that the rubber-like elastic body is not cut and the rubber particles are not broken.
[0012]
The volume ratio of the tubular reactor constituting the annular reactor to the reactor having the stirring blade is 5/1 to 20/1. When this ratio is less than 5/1, the residence time in the reactor equipped with the stirring blade becomes longer, the particle size distribution is spread due to the residence time distribution, the rubber particles are enlarged, and the rubber particle diameter is controlled. Becomes difficult. If this ratio is large, it is difficult to control the degree of mixing of the raw material solution and the polymerization solution, and as a result, it becomes difficult to control the rubber particle diameter.
[0013]
One or more organic peroxide solutions need to be fed anywhere in the tubular reactor (II). When the monomer conversion rate increases, the reaction rate decreases, leading to a decrease in productivity. Further, the rubber particles formed in the annular reactor are not grafted with polystyrene on the surface or are insufficient even if they are formed. It is necessary to graft polystyrene in a tubular reactor (II) in order to increase strength, appearance characteristics and the like. To achieve these objectives, it is necessary to supply an organic peroxide solution to increase the reaction rate and accelerate the graft reaction. It is preferable that one or more supply sites of the organic peroxide solution be provided. The supply site of the organic peroxide solution is not particularly limited. In the case of one place, the inlet of the tubular reactor (II) and in the case of two places, the inlet and the center of the tubular reactor (II) preferable. In the case of three or more locations, it is preferable to supply the tubular reactor (II) to equally divided locations. The organic peroxide solution may be supplied alone or diluted with a solvent such as ethylbenzene. The organic peroxide used is not particularly limited, but has a 10-hour half-life temperature of 90 to 140 ° C., for example, Perhexa C, Perhexa 3M, Perbutyl Z, Perbutyl D, Perhexa 25B, Perbutyl I, etc. of NOF Corporation. Is preferably used.
[0014]
The volume ratio between the annular reactor (I) and the tubular reactor (II) is 1/1 to 1/5. Preferably, it is 1/1 to 1/3. When this ratio is larger than 1/1, the reaction rate of the annular reactor (I) is somewhat restricted from the viewpoint of rubber particle diameter control, and the load for improving productivity in the tubular reactor (II) increases. , The balance between quality and productivity gets worse. If this ratio is smaller than 1/3, the productivity per unit volume will be poor. The productivity referred to in the present invention refers to a production amount per unit volume and per unit time. The conventional production process and production conditions are 1-2 tons / m ³ / day, but the high productivity referred to in the present invention means a value of about ^{3 to} 5 tons / m ³ / day.
[0015]
The rubber-reinforced styrene resin referred to in the present invention is a polymer having a continuous phase of styrene, α-methylstyrene, or the like, or styrene, a monomer copolymerizable with α-methylstyrene, (meth) acrylate, for example, Butyl acrylate, methyl methacrylate, butyl methacrylate, methyl acrylate, etc., and copolymers such as acrylonitrile, the dispersed phase is polybutadiene, styrene / butadiene copolymer, styrene / butadiene block copolymer, ethylene / propylene terpolymer, etc. It is a resin composed of rubber particles formed by a rubber-like elastic body.
[0016]
The raw material solution referred to in the present invention is a solution in which a rubber-like elastic material is dissolved in a monomer, and a polymerization solvent such as ethylbenzene or toluene, a molecular weight modifier, and a 10-hour half-life temperature of 90 to 140 ° C., if necessary. For example, a polymerization initiator such as Perhexa C, Perhexa 3M, Perbutyl Z, Perbutyl D, Perhexa 25B, Perbutyl I and the like, a plasticizer such as mineral oil and silicone oil, an antioxidant and the like are added to the raw material solution. You may.
[0017]
The raw material solution is supplied to a reactor equipped with a stirring blade, but a pretreatment such as prepolymerization may be performed at a stage before the raw material solution is supplied to a reactor equipped with a stirring blade. However, it is important to keep the conversion rate at which the rubber-like elastic body does not form rubber particles.
The polymerization temperature of the cyclic reactor (I) is preferably in the range of 100 to 150 ° C. The circulation amount of the annular reactor is not particularly limited, but it is necessary to use the static mixer at a flow rate higher than the minimum flow rate at which the mixing capacity can be sufficiently exhibited.
[0018]
For example, in the case of an SMR reactor manufactured by Sluzer, it is preferable to circulate at a circulation amount capable of obtaining a flow rate of 2 m / h or more. A circulation ratio (circulation flow rate / raw material solution supply flow rate) of 2 to 15 is preferably used. Although it is possible to control the rubber particle diameter by changing the circulation ratio, the degree of freedom to control is small. However, there is no problem in finely adjusting the rubber particle diameter by the circulation amount in consideration of the pressure loss and the like.
[0019]
The polymerization temperature in the tubular reactor (II) is preferably in the range of 120 to 180 ° C. The polymerization conditions are preferably set so that the concentration of the solid content (the total of the polymer in the continuous phase and the dispersed phase) at the outlet of the tubular reactor (II) is 70% by weight or more, preferably 80% by weight or more. If the solid content concentration is low, the load on the recovery capacity increases in order to maintain high productivity, which is not preferable.
[0020]
The polymerization solution discharged from the tubular reactor (II) is sent to a recovery facility, where unreacted monomers, a polymerization solvent, and the like are removed and pelletized. Before entering the recovery system, or after exiting the recovery system, it is possible to add additives frequently used in the rubber-reinforced styrenic resin, for example, antioxidants, plasticizers, coloring agents, antistatic agents, flame retardants and the like. it can.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
The measuring method of physical properties and the like is based on the following methods.
SOLID%: Approximately 5 g of the polymerization solution was precisely weighed, and after adding about 5 cc of methanol, the mixture was heated in a vacuum drier at 200 ° C. and 10 mmHg for 20 minutes and then precisely weighed to calculate the solid concentration (% by weight). I do.
[0022]
Rubber particle size, particle size distribution: Measured using a Coulter Counter of the following model manufactured by Coulter Corporation.
Main unit: MULTISIZER II type, Measuring instrument: MULTISIZER IIE type, using an electrolytic solution composed of dimethylformamide and ammonium thiocyanate, and obtaining a 50% median diameter of volume average and number average. The rubber particle diameter as referred to in the present invention means a volume average 50% median diameter, and the rubber particle diameter distribution means a ratio of a volume average 50% median diameter to a number average 50% median diameter.
[0023]
Izod impact strength: Measured according to ASTM D638I.
Appearance: A dumbbell test piece was molded under the conditions of a molding temperature of 220 ° C. and a mold temperature of 60 ° C., and a position 4 cm from the gate side was measured in accordance with JIS Z8741.
FIG. 1 is a schematic flow sheet of the apparatus used to carry out the method of the present invention. The raw material solution prepared in the tank (1) is sent to the reactor (3) by the pump (2). The reactor (3) is a plug flow type reactor having L / D = 10, 15-stage rod-shaped blades, and a capacity of 0.6 L. The polymerization solution leaving the reactor (3) is sent to the reactor (4). The reactor (4) is a Sluzer SMR type tubular reactor with a built-in static mixer having a flow path through which a heat medium passes. The volume is 6L. A part of the polymerization solution leaving the reactor (4) is circulated to the reactor (3) by a pop (5). The remaining polymerization solution is sent to the reactor (6). Reactor (6) has the same structure as reactor (4) and has a volume of 12L. The initiator solution can be added to the inlet and the middle of the reactor (6) by the pumps (7) and (8). The polymerization solution exiting the reactor (6) is sent to a twin-screw extruder (9) equipped with a two-stage vent to remove unreacted monomers, polymerization solvent and the like, and then pelletized.
[0024]
Embodiment 1
81.5% by weight of styrene, 12% by weight of ethylbenzene, 6.5% by weight of rubber (Asaprene 730A, manufactured by Asahi Chemical Industry Co., Ltd.), 300 ppm of organic peroxide (Perhexa C, manufactured by NOF Corporation), α-methylstyrene dimer The mixture is prepared in the tank (1) so as to have a concentration of 200 ppm to prepare a raw material solution.
[0025]
The raw material solution is supplied to the reactor (3) at a rate of 3.5 L / H. The reactor (3) and the reactor (4) are controlled at 123 ° C. The rotation speed of the reactor (3) is controlled at 100 rpm, and the circulation ratio (circulation flow rate / raw material solution flow rate) is controlled at 10. The polymerization solution leaving the reactor (4) is sent to the reactor (6), and the reactor (6) is controlled at 145 ° C. in the first stage and at 160 ° C. in the second stage. Using a pump (7), 300 ppm of an organic peroxide (a 50% by weight solution of perhexa C in ethylbenzene) is added to the polymerization solution.
[0026]
The polymerization solution exiting the reactor (6) is sent to a twin-screw extruder (9) with a two-stage vent, where it is treated at a temperature of 240 ° C. and pelletized. Table 1 shows the results.
[0027]
Embodiment 2
Pellets are obtained in the same manner as in Example 1 except that the stirring number of the reactor (3) is 180 rpm. Table 1 shows the results.
[0028]
Embodiment 3
Pellets are obtained in the same manner as in Example 1, except that the reactor (3) and the reactor (4) are controlled at 114 ° C., the former stage of the reactor (6) is controlled at 150 ° C., and the latter stage at 170 ° C. Table 1 shows the results.
[0029]
Embodiment 4
Pellets are obtained in the same manner as in Example 3, except that the stirring number of the reactor (3) is 180 rpm. Table 1 shows the results.
[0030]
Embodiment 5
Pellets are obtained in the same manner as in Example 1 except that the reactor (3) and the reactor (4) are controlled at 119 ° C., the former stage of the reactor (6) is controlled at 147 ° C., and the latter stage is controlled at 165 ° C. Table 1 shows the results.
[0031]
[Comparative Example 1]
In FIG. 1, pellets are obtained in the same manner as in Example 1 except that the raw material solution and the polymerization solution circulated by the pump (5) are directly supplied to the reactor (4) except for the reactor (3). . Table 1 shows the results.
[0032]
[Comparative Example 2]
Pellets are obtained in the same manner as in Comparative Example 1 except that the circulation ratio is 15. Table 1 shows the results.
[0033]
[Comparative Example 3]
Pellets are obtained in the same manner as in Comparative Example 1 except that the temperature of the reactor (4) is 114 ° C. Table 1 shows the results.
[0034]
[Comparative Example 4]
Pellets are obtained in the same manner as in Example 1, except that the organic peroxide is not added using the pump (7). Table 1 shows the results.
[0035]
[Comparative Example 5]
Pellets are obtained in the same manner as in Example 3, except that the organic peroxide is not added using the pump (7). Table 1 shows the results.
[0036]
[Table 1]

[0037]
Embodiment 6
The capacity of the reactor (6) in FIG. 1 is 9 L, and 200 ppm of an organic peroxide (a 50% by weight solution of perbutyl D in ethylbenzene, manufactured by NOF CORPORATION) is added by a pump (8). 6) A pellet is obtained in the same manner as in Example 1, except that the latter stage (volume 3 L) is controlled at 165 ° C. The position to be added by the pump (8) is 2/3 from the inlet of the reactor (6). The SOLID% of the polymerization solution leaving the reactor (6) is 86%. Table 2 shows the results.
[0038]
[Comparative Example 6]
Three reactors having a structure similar to the reactor (3) and having a volume of 6 L are arranged in series, and a raw material solution having the same composition as in Example 1 is supplied at 2.5 L / H, and the first-stage reaction is performed. The temperature of the reactor was controlled at 120-125 ° C, the temperature of the second reactor was controlled at 135-145 ° C, and the temperature of the third reactor was controlled at 155-165 ° C. It is sent to a twin screw extruder (9), processed at a temperature of 240 ° C. and pelletized. The SOLID% of the polymerization solution exiting the third stage reactor is 73%. Table 2 shows the results.
[0039]
[Table 2]

[0040]
[Comparative Example 7]
Using the same apparatus as in Comparative Example 6, a raw material solution having the same composition as in Example 1 was supplied at 3.5 L / H, and the temperature of the two-stage reactor was 135 to 150 ° C and the temperature of the three-stage reactor was 150 to 170. While controlling the temperature in the range of ° C., the operation was performed such that the SOLID% of the polymerization solution exiting the third-stage reactor was about 75%, but a runaway reaction and a stall reaction were repeated, and a stable operation could not be performed. High productivity could not be achieved with this process.
[0041]
【The invention's effect】
By using the method for producing a rubber-reinforced styrenic resin of the present invention, it is easy to control the rubber particle diameter in a wide rubber particle diameter range from a large rubber particle diameter to a small rubber particle diameter. Then, a rubber-reinforced styrene-based resin excellent in strength, appearance, and the like and excellent in productivity can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of a tubular reactor.
FIG. 2 is a schematic flow sheet of the apparatus used to carry out the method of the present invention.

Claims

An annular reactor (I) comprising a tubular reactor having a built-in static mixer having a flow path through which a heat medium flows, a reactor having a stirring blade, and a pump for transferring a reaction solution, and a flow path through which the heat medium flows A raw material solution containing a styrenic monomer and a rubbery polymer is supplied to a reactor equipped with stirring blades, and the annular reactor (I) is provided with a static mixer. A polymerization method for supplying to a tubular reactor (II) while partially circulating, wherein a volume ratio of the tubular reactor constituting the annular reactor (I) to a reactor having a stirring blade is 5/1 to 20 /. 1, wherein the volume ratio of the annular reactor (I) to the tubular reactor (II) is 1/1 to 1/5, and the organic reactor is disposed in at least one location in the tubular reactor (II). It supplies an oxide solution, and the polymer concentration of a reactor equipped with a stirring blade in the reactor (I) is a raw material. Method of manufacturing a and controls to be 2 to 10 times of the rubber-like elastic material density, rubber-reinforced styrene resin rubbery elastomer in the styrene resin phase consecutive dispersed in particulate form.

The tubular reactor constituting the annular reactor (I) has a static mixing structure having a structure through which a heat medium can pass, and is fixed inside. The heat transfer area per unit volume (A / V) ^{2. The} method for producing a rubber-reinforced styrenic resin according to claim 1 , wherein the value of is not less than 30 (m ² / m ³ ). "