JP3665225B2 - Method for producing unvulcanized rubber composition - Google Patents

Method for producing unvulcanized rubber composition Download PDF

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JP3665225B2
JP3665225B2 JP09481599A JP9481599A JP3665225B2 JP 3665225 B2 JP3665225 B2 JP 3665225B2 JP 09481599 A JP09481599 A JP 09481599A JP 9481599 A JP9481599 A JP 9481599A JP 3665225 B2 JP3665225 B2 JP 3665225B2
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rubber
kneading
mixing
mixing tank
agent
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JP2000280236A (en
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秀久 仁科
武志 植田
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Kurashiki Kako Co Ltd
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Kurashiki Kako Co Ltd
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Description

【0001】
【発明の属する技術分野】
本発明は、ゴム製品の加工に使用される未加硫ゴム組成物の製造方法に関する。
【0002】
【従来の技術】
一般にゴム製品の加工に用いられる未加硫ゴム組成物は、以下のような三つのゴム練りステップを経て製造される(ここで「ステップ」は、ゴムのゴム練り機への投入、ゴム練り、練ったゴムのゴム練り機からの取り出しを含んだ概念を意味する。以下同様。)。
【0003】
第一に、ゴム配合物を含まない原料ゴムをゴム練り機により単独で練る。このゴム練りステップを素練りステップといい、これによって原料ゴムの分子鎖が切断され、分子鎖の長さが平均化される。加えて、原料ゴムの弾性が減じ可塑化が高まり、以後のゴム練り加工性が良好なものとなる。第二に、素練りを終えた原料ゴムにカーボンブラック、可塑剤(オイル)、ステアリン酸、老化防止剤等のゴム配合剤を投入してゴム練り機により全体を練り混ぜる。このゴム練りステップを混練りステップといい、これらのゴム配合剤が原料ゴムに混ざることにより、加硫後のゴム製品の強度を高める、ゴムの混練り加工性が良好とする、ゴム分子鎖の切断により生じたラジカルに起因するゴムの劣化が防止する等の効果が得られる。第三に、混練りされたゴム配合物に所要量の加硫剤を投入して全体を練り混ぜる。このゴム練りステップを加硫剤ミキシングステップという。加硫剤は、ゴム分子と反応し、ゴム分子間に橋架け構造を形成して分子を三次元ネットワーク化させ、ゴム弾性を付与するものである。
【0004】
そして、これら三つのゴム練りステップは、連続して行われるものではなく、断続的に、しかも複数種のゴム練り機を使用して行われるものである。例えば、素練りをバンバリーミキサーで行った後、混練りをニーダーで行い、さらに加硫剤ミキシングをロールミキサーで行う場合が挙げられる。
【0005】
【発明が解決しようとする課題】
しかしながら各ゴム練りステップを別個独立とした従来の未加硫ゴムの製造方法では、以下のような問題点がある。
【0006】
まず、ゴムの投入や取り出しなどゴム練りに付随する同一の作業が、各ゴム練りステップ毎に繰り返し行われるため、ゴム練りステップ全体として効率が悪いという問題がある。
【0007】
また、各ゴム練りステップにおいて、ゴム練り加工性を良好なものとするためにゴムに熱が加えられるが、各ゴム練りステップが断続的に行われると、素練りステップで一旦ゴムの温度が上昇しても、素練り用ゴム練り機から混練り用ゴム練り機にゴムを移す過程でそのゴムが冷え、混練りステップの段階では再度ゴムに熱を加える必要がある。同様に混練りステップで一旦ゴムの温度が上昇しても、加硫剤ミキシングステップの段階では、ゴムの温度は必要以上に下がっている場合もあり、そのときには再度ゴムに熱を加える必要がある。従って、ゴム練りステップ全体として、ゴムの温度を上げるために無駄なエネルギーが費やされるという不都合がある。
【0008】
さらに、各ゴム練りステップ毎に異なるゴム練り機を用いると、複数種のゴム練り機を設置するためのスペースを工場内に確保する必要があるという問題もある。
【0009】
そして、上述のようにゴム練りステップの作業効率が悪く、エネルギーを無駄にするため、未加硫ゴムの製造に要する費用が高くなるという不都合もある。
【0010】
本発明は、かかる点に鑑みてなされたものであり、その目的とするところは、素練り、混練り及び加硫剤ミキシングの三つのゴム練りステップを連続して一台のゴム練り機で行うことにより、未加硫ゴムの製造の省力化、省スペース化、省エネルギー化及びコストダウンを図ることにある。
【0011】
【課題を解決するための手段】
本発明は、未加硫ゴムの製造方法において、素練り、混練り及び加硫剤ミキシングの三つの練りステップを連続して一台のゴム練り機の同一の混合槽で行うこととしたものである。
【0012】
具体的には、請求項1記載の発明は、ゴム製品の加工に使用される未加硫ゴム組成物の製造方法であって、
ゴム配合剤を含まない原料ゴムを、一対のロータを有する混合槽を備えると共に、前記混合槽内を温度調節する水を流す通水路が設けられた噛み合い式ミキサーであるゴム練り機の前記混合槽に投入する原料ゴム投入工程と、
前記原料ゴムを前記ゴム練り機の前記混合槽内で練る素練り工程と、
前記素練り工程後の素練り済み原料ゴムに混合するゴム配合剤を、加硫剤を除いて前記ゴム練り機の前記混合槽に投入するゴム配合剤投入工程と、
前記素練り工程後の前記素練り済み原料ゴムと前記加硫剤を除く前記ゴム配合剤とを前記ゴム練り機の前記混合槽内で混合する混練り工程と、
前記混練り工程後の混練り済みゴム組成物の温度を、前記通水路に流す水の温度を下げると共に、前記ゴム練り機の前記混合槽内で前記一対のロータを回転させることにより下げる冷却工程と、
前記冷却工程後の前記混練り済みゴム組成物に混合する前記加硫剤を、前記ゴム練り機の前記混合槽に投入する加硫剤投入工程と、
前記冷却工程後の前記混練り済みゴム組成物と前記加硫剤とを前記ゴム練り機の前記混合槽内で混合する加硫剤ミキシング工程と、
を備え、
これらすべての工程を同一の前記ゴム練り機の同一の前記混合槽内において行うことを特徴とする未加硫ゴム組成物の製造方法である。
【0013】
上記の未加硫ゴム組成物の製造方法において、ゴム配合剤を含まない原料ゴムの投入、素練り、加硫剤を除くゴム配合剤の投入、混練り、冷却、加硫剤投入及び加硫剤ミキシングの各工程は、一台のゴム練り機の同一の混合槽において連続して行われているので、ゴムの投入・取り出し等を各ゴム練りステップ毎に行う必要がなくなる。従って、ゴム練り作業の合理化・省力化を図ることができる。
【0014】
また、素練り工程後、加硫剤を除くゴム配合剤を投入し、引き続き混練り工程に移り、混練り工程後、ゴムを冷却して加硫剤を投入し、引き続き加硫剤ミキシングに移る。すなわち、ゴムはある程度温度が上がった状態で混練り工程又は加硫剤ミキシング工程に移行することとなり、従来のような温度の低下分を補うための加熱は必要がない。従って、ゴム練りステップ全体として省エネルギー化を図ることができる。
【0015】
さらに、一台のゴム練り機の同一の混合槽でゴム配合剤を含まない原料ゴムの投入から加硫剤のミキシングまでを行えるので、複数種のゴム練り機を設置する必要がなく、工場の省スペース化を図ることができる。
【0016】
そして、上記のゴム練りステップの合理化・省力化及び省エネルギー化に起因してゴム練りステップ全体としてコストダウンを図ることができる。
【0017】
なお、加硫剤ミキシング工程でゴムの変形に伴う発熱が大きいと、この工程でゴムの加硫が進行することとなる。
【0018】
また、加硫剤ミキシング工程の時間が長くなった場合でも、ゴムに高温下での温度履歴を与えることとなり、ゴムの加硫進行の原因となる。従って、加硫剤のミキシングは、できるだけ短時間で行えることが好ましい。
【0019】
さらに、本未加硫ゴム組成物の製造方法を適用できるゴム種としては、天然ゴム、クロロプレンゴム(CR)、ニトリルゴム(NBR)、アクリルゴム(ACM)、エチレン−プロピレンゴム(EPDM)等の単独種のゴム、2種以上のゴムの混合物、ゴムと他のポリマーとの混合物をも挙げることができるが、上記の加硫剤ミキシング工程におけるゴムの加硫進行を防止するという観点から、比熱が小さく冷却容易な天然ゴム、クロロプレンゴム(CR)、ニトリルゴム(NBR)への適用が特に好ましい。
【0020】
原料ゴム投入工程では、ゴム練り機の混合槽内のロータを止めて原料ゴムを投入してもよいが、そうするとロータの駆動時に高トルクが必要となり、ゴム練り機の故障をまねくおそれがある。従って、ゴム練り機の混合槽内のロータを回転させながら原料ゴムを投入することが好ましい。
【0021】
素練り工程におけるゴムの温度は、ゴムの練り加工性とゴムの熱劣化防止のバランスをとる観点から130±20℃とすることが好ましい。
【0022】
配合剤投入工程では、ゴム練り機の混合槽内のロータを停止してゴム配合剤を投入してもよいが、順次投入されるゴム配合剤を迅速にゴムに分散させるためには、素練りに引き続きゴムを練りながらゴム配合剤を投入することが好ましい。
【0023】
混練り工程におけるゴムの温度も素練り工程の場合と同様にゴムの練り加工性とゴムの熱劣化防止のバランスをとる観点から130±20℃とすることが好ましい。
【0024】
冷却工程は、混練り工程終了後、ゴム全体の温度を迅速に下げるために、ゴム練り機の混合槽内のロータを低速で回転させながらゴムを冷却する。また、混練り工程終盤にゴム組成物が均一化した後、ゴム練り機の混合槽内のローターを回転させながらゴムの冷却を開始してもよい。
【0025】
加硫剤投入工程では、ゴム練り機の混合槽内のロータを停止して加硫剤を投入してもよいが、加硫剤を迅速にゴムに分散させるためには、ゴム練り機の混合槽内のロータを回転させながら加硫剤を投入することが好ましい。
【0026】
加硫剤ミキシング工程におけるゴムの温度は、ゴムの練り加工性とゴムの加硫進行防止のバランスをとる観点から95±10℃とすることが好ましい。
【0027】
また、前記ゴム練り機は冷却効率に優れる噛み合い式ミキサーであるので、混練り工程から加硫剤ミキシング工程へ移行する際のゴムの冷却が迅速になされるとともに、加硫剤ミキシング工程においてゴムの加硫進行を効果的に防止することができる。ここで噛み合い式ミキサーとは、噛み合い式バンバリーミキサーや噛み合い式ニーダーをいう。
【0028】
請求項記載の発明は、請求項1または請求項2記載の未加硫ゴム組成物の製造方法であって、
前記原料ゴム投入工程において、前記ゴム配合剤を含まない前記原料ゴムとともにシャッ解剤を前記ゴム練り機の前記混合槽に投入し、
前記素練り工程において、前記ゴム配合剤を含まない前記原料ゴムをシャッ解剤とともに素練りすることを特徴とする未加硫ゴム組成物の製造方法である。
【0029】
かかる未加硫ゴム組成物の製造方法において、原料ゴムはシャッ解剤とともに素練りされるので、原料ゴムの粘度は下がり、素練り加工性を向上させることができる。従って、原料ゴムは全体的に均一に素練りされ、品質にばらつきのない素練り済みゴムを得ることができる。なお、シャッ解剤としては、ジ−(ベンズアミドフェニル)ジスルフィド等がある。そして、シャッ解剤は、原料ゴムの粘度を下げる目的で添加されるものであり、ゴム配合剤とは異質のものである。
【0030】
【発明の効果】
上記説明したように、請求項1記載の発明によれば、ゴム配合剤を含まない原料ゴムの投入、素練り、加硫剤を除くゴム配合剤の投入、混練り、冷却、加硫剤の投入及び加硫剤ミキシングの取り出しの各工程は、一台のゴム練り機の同一の混練槽において連続して行われているので、ゴム練りステップの合理化・省力化を図ることができる。加えて、混練りステップ及び加硫剤ミキシングステップで従来のようなゴムの温度の低下分を補うための加熱は必要でないため、ゴム練りステップ全体として省エネルギー化を図ることができる。さらに、一台のゴム練り機の同一の混練槽においてゴム配合剤を含まない原料ゴムの投入から加硫剤のミキシングまで行えるので、複数種のゴム練り機を設置する必要がなく、工場の省スペース化を図ることができる。そして、ゴム練りステップの省力化・合理化及び省エネルギー化が図られるので、ゴム練りステップ全体としてのコストダウンを図ることができる。また、ゴム練り機が噛み合い式ミキサーであることから、混練り済みゴム の冷却が迅速になされるとともに、加硫剤ミキシング工程におけるゴムの加硫進行を効果的に防止することができる。
【0031】
さらに、請求項記載の発明によれば、請求項2又は請求項3記載の発明の効果に加えて、原料ゴムがシャッ解剤とともに素練りされるので、素練りの加工性が向上し、素練り済みゴムの品質安定化を図ることができる。
【0032】
【発明の実施の形態】
以下、本発明の実施形態として噛み合い式ニーダーを用いた未加硫ゴムの製造方法について図面に基づき詳細に説明する。
【0033】
<噛み合い式ニーダー>
図1は、本発明である未加硫ゴム組成物の製造方法に使用される噛み合い式ニーダーのゴム練り部断面を示す。噛み合い式ニーダーのゴム練り部は、一対のロータ1a,1bと混合槽2と加圧シリンダー3とからなる。
【0034】
一対のロータ1a,1bは、混合槽2内に並列して設置されている。そして、各ロータ1a,1bは、両ロータ1a,1b間上部にゴムを置いた場合、そのゴムを下方に押し出す方向へ互いに逆方向に回転する。また、ロータ1aの羽根の軌跡とロータ1bの羽根の軌跡は、それぞれのロータ1a,1bの軸間中央付近において重複する部分を有する。しかしながら、ロータ1a,1bは両者の間に常に隙間を形成し、互いに接触することなく回転する。そして、この隙間をゴムが通過することにより、ゴムにせん断変形が加わり、ゴムが練られることとなる。
【0035】
混合槽2は、ロータ1a,1bを囲っており、混合槽2内部でゴムが練られるものである。また、混合槽2内壁とロータ1a,1bの間の隙間をゴムが通過することによってもゴムにせん断変形が加わり、ゴムが練られることとなる。なお、混合槽2には、ゴムの温度を感知するための温度センサー21が取り付けられている。
【0036】
加圧シリンダー3は、混合槽2の蓋としての役割を果たし、加圧シリンダー3が上がり混合槽2が開口した際には、その開口部が原料ゴム、ゴム配合剤、加硫剤の投入口及び練り上がった未加硫ゴム組成物の取り出し口となり、加圧シリンダー3が降りて閉口した際には、混合槽2の開口部を密閉し、ゴム配合剤等の飛散を防止する役割を果たす。
【0037】
なお、噛み合いニーダーのゴム練り部内部の温度調節は、蒸気と冷却水の混合割合により温度調節された水をローター1a,1b、混合槽2及び加圧シリンダー3内部に設けられた通水路に流すことにより行われる。
【0038】
図2は、上記噛み合い式ニーダーの制御機構を表した図である。ゴム練り部の混合槽2には、温度センサー21が取り付けられており、これが練っているゴムの温度を感知する。続いて、それは電気信号に変換され、制御装置に入力される。 <ゴム練りステップ>
図3は、未加硫ゴム組成物の製造方法における工程順序を表す。
【0039】
まず、原料ゴム投入工程である。この工程では、加圧シリンダー3を上げ、混合槽2を開口状態にし、ロータ1a,1bを回転させながら混合槽2の開口部からゴム配合剤を含まない原料ゴムを投入する。このとき、原料ゴムの粘度を下げ、素練り加工性を向上させるためにシャッ解剤を原料ゴムとともに投入する。
【0040】
次に、素練り工程である。この工程では、加圧シリンダー3を下げ、混合槽2の開口部を密閉し、ロータ1a,1bの回転により原料ゴムを練る。素練りにより原料ゴムの分子鎖が切断され、分子鎖の長さが平均化される。加えて、原料ゴムの弾性が減じ可塑化が高められ、以後のゴム練り加工性が良好なものとなる。なお、混合槽2に取り付けられた温度センサー21はゴムの温度を感知し、それが電気信号に変換されて制御装置に送られる。そして、その信号に基づいてPIDコントローラに信号が出力され、冷却水と蒸気とが繋がったバルブが制御される。
【0041】
続いて、ゴム配合剤投入工程である。この工程では、加圧シリンダー3を上げ、混合槽2を開口状態にし、混合槽2の開口部からカーボンブラック、ステアリン酸、老化防止剤等の加硫剤を除くゴム配合剤を投入する。なお、このゴム配合剤の投入は、ロータ1a,1bを回転させた状態で行う。
【0042】
次に、混練り工程である。この工程では、加圧シリンダー3を下げ、混合槽2の開口部を密閉し、ロータ1a,1bの回転により素練り済み原料ゴムと投入したゴム配合剤とを練り合わせる。ゴム配合剤がゴムに混ざることにより、加硫後のゴム製品の強度が高まる、ゴムの混練り加工性が良好となる、ゴム分子鎖の切断により生じたラジカルに起因するゴムの劣化が防止する等の効果が得られる。なお、混合槽2に取り付けられた温度センサー21はゴムの温度を感知し、それが電気信号に変換されて制御装置に送られる。そして、その信号に基づいてPIDコントローラに信号が出力され、冷却水と蒸気とが繋がったバルブが制御される。この点、素練り工程と同様の制御がなされる。
【0043】
続いて、冷却工程である。この工程では、加圧シリンダー3を上げ、混合槽2を開口状態とし、通水路を通す水の温度を下げてゴムの温度を下げる。これは、加硫剤を投入した後、加硫剤ミキシング段階でゴムの加硫が進行するのを防止しようとするものである。ここで通水路を通る水の温度調節は、制御装置からPIDコントローラに信号が送られ、これによってバルブを制御し、冷却水と蒸気の割合を調節して行われる。なお、ロータ1a,1bを低速で回転させながらゴムを冷却するとゴム全体が均一に冷却されるので効率的である。
【0044】
次に、加硫剤投入工程である。この工程では、混合槽2の開口部から加硫剤を投入する。なお、この加硫剤の投入は、ロータ1a,1bを回転させた状態で行う。
【0045】
そして、加硫剤ミキシング工程である。この工程では、加圧シリンダー3を下げ、混合槽2の開口部を密閉し、ロータ1a,1bの回転により混練り済みゴムと投入した加硫剤とを練り合わせる。この加硫剤が、高温下でゴム分子と反応し、ゴム分子間に橋架け構造を形成して分子を三次元ネットワーク化させ、加硫後ゴム組成物にゴム弾性を付与するものである。なお、混合槽2に取り付けられた温度センサー21はゴムの温度を感知し、それが電気信号に変換されて制御装置に送られる。そして、その信号に基づいてPIDコントローラに信号が出力され、冷却水と蒸気とが繋がったバルブが制御される。この点、素練り工程及び混練り工程と同様の制御がなされる。
【0046】
以上の一連の工程を一台の噛み合い式ニーダーにおいて行うことにより、未加硫ゴム組成物が製造される。
【0047】
次に、本実施形態である未加硫ゴム組成物の製造方法における作用・効果について説明する。
【0048】
本実施形態に係る未加硫ゴム組成物の製造方法では、ゴム配合剤を含まない原料ゴムの投入、素練り、加硫剤を除くゴム配合剤の投入、混練り、冷却、加硫剤投入及び加硫剤ミキシングの各工程が、一台の噛み合い式ニーダーの同一の混合槽において連続して行われているので、ゴムの投入・取り出し等を各ゴム練りステップ毎に行う必要がなくなる。従って、ゴム練りステップの合理化・省力化を図ることができる。
【0049】
また、素練り工程後、加硫剤を除くゴム配合剤を投入し、引き続き混練り工程に移り、混練り工程後、ゴムを冷却して加硫剤を投入し、引き続き加硫剤ミキシングに移る。すなわち、ゴムはある程度温度が上がった状態で混練り工程又は加硫剤ミキシング工程に移行することとなり、従来のような温度の低下分を補うための加熱は必要でない。従って、ゴム練りステップ全体として省エネルギー化を図ることができる。
【0050】
さらに、一台の噛み合い式ニーダーの同一の混合槽でゴム配合剤を含まない原料ゴムの投入から加硫剤のミキシングまでを行えるので、複数種のゴム練り機を設置する必要がなく、工場の省スペース化を図ることができる。
【0051】
そして、上記のゴム練りステップの合理化・省力化及び省エネルギー化に起因してゴム練りステップ全体としてコストダウンを図ることができる。
【0052】
また、ゴム練り機として冷却効率の良い噛み合いニーダーを用いているので、混練り工程から加硫剤ミキシング工程へ移行する際のゴムの冷却が迅速になされるとともに、加硫剤ミキシング工程においてゴムの加硫進行を効果的に防止することができる。
【0053】
そして、シャッ解剤が原料ゴムとともに投入され、素練りされるので、原料ゴムの粘度が低下し、原料ゴムの素練り加工性を向上させることができる。従って、原料ゴムは全体的に均一に素練りされ、品質にばらつきのない素練り済みゴムを得ることができる。
【0054】
<本発明の適用例1>
上記の未加硫ゴム製造方法を天然ゴムに適用した例について説明する。ゴム配合は表1に示すとおりである(なお、表中のphrは、原料ゴム100重量部に対し、投入される各ゴム配合剤の重量部を表す単位である。)
【0055】
【表1】

Figure 0003665225
【0056】
配合剤を含まない原料ゴムは天然ゴムである。加硫剤を除くゴム配合剤は、可塑剤、FEFカーボンブラック、炭酸カルシウム、酸化亜鉛、ステアリン酸、ワックス、老化防止剤及び加硫促進剤である。そして、加硫剤はイオウである。
【0057】
図4に本発明の適用例1の工程図を示す。図において、横方向は時間の経過を示す。また、縦方向の上部平坦部は噛み合いニーダーの混合槽2が閉口している状態、つまりは加圧シリンダーが降りている状態を示し、下部平坦部は、混合槽2が開口している状態、つまりは加圧シリンダーが上がっている状態を示す。
【0058】
まず、噛み合いニーダーのロータ1a,1bを回転させ、混合槽2の開口部から天然ゴムとシャッ解剤としてジ−(ベンズアミドフェニル)ジスルフィドを0.3phrを投入した。そして、加圧シリンダー3を下げ、天然ゴムの素練りを行った。このときロータ1a,1b回転数は40rpm、通水路を流れる水の温度は60℃に設定した。素練りは120秒間行い、素練り終了時のゴムの温度は125℃であった。
【0059】
次に、ロータ1a,1bを40rpmで回転させながら加圧シリンダー3を上げ、混合槽2の開口部から加硫剤を除くゴム配合剤を投入した。再び加圧シリンダーを下げ、ロータ1a,1bの回転数を40rpmとしたまま混練りを行った。混練りは100秒間行い、混練り終了時のゴムの温度は125℃であった。なお、通水路を流れる水の温度は、混練り開始後60秒までは60℃に設定してあったが、それ以降は25℃に移行させた。
【0060】
続いて、加圧シリンダー3を上げ、ロータ1a,1bの回転数を5rpmに下げてゴムの冷却を行った。冷却は150秒間行い、冷却終了時のゴムの温度は90℃であった。
【0061】
次に、混合槽2の開口部からイオウを投入し、再び加圧シリンダー3を下げ、ロータ1a,1bの回転数を20rpmに設定して加硫剤のミキシングを行った。加硫剤のミキシングは60秒間行った。なお、ミキシング開始後40秒後に、加圧シリンダー3を一旦上げ、すぐに下げるという操作を行った。このときゴムは、加圧シリンダー3と共に一旦上がり、そしてロータ1a,1bによって下方に引き戻されるという挙動を示した。このように定常的な練り状態を一旦断ち、別の定常的な練り状態に移行させることによって、イオウを含めゴム配合剤の分散性を向上させることができる。
【0062】
最後に練り上がった未加硫天然ゴム組成物を混合槽2から取り出した。このときゴムの温度は95℃であった。
【0063】
<本発明の適用例2>
上記の未加硫ゴム製造方法をニトリルゴム(NBR)と塩化ビニル(PVC)の混合物に適用した例について説明する。ゴム配合は表2に示すとおりである。
【0064】
【表2】
Figure 0003665225
【0065】
配合剤を含まない原料ゴムはニトリルゴム(NBR)と塩化ビニル(PVC)の混合物である。加硫剤を除くゴム配合剤は、液状ニトリルゴム、FEFカーボンブラック、シリカ、酸化亜鉛、ステアリン酸、老化防止剤及び加硫促進剤である。そして、加硫剤はイオウである。
【0066】
図5に本発明の適用例2の工程図を示す。図の内容は図4の場合と同じである。
【0067】
まず、噛み合いニーダーのロータ1a,1bを回転させ、混合槽2の開口部からニトリルゴム(NBR)と塩化ビニル(PVC)の混合物を投入した。そして加圧シリンダー3を下げ、ニトリルゴム(NBR)と塩化ビニル(PVC)の混合物の素練りを行った。このときロータ1a,1b回転数は30rpm、通水路を流れる水は60℃に設定した。素練りは50秒間行い、素練り終了時のゴムの温度は140℃であった。
【0068】
次に、加圧シリンダー3を上げ、ロータ1a,1b回転数の設定を40rpmとして回転させながら開口部から加硫剤を除くゴム配合剤を投入した。再び加圧シリンダーを下げ、ロータ1a,1bの回転数を40rpmとしたまま混練りを行った。混練りは120秒間行い、混練り終了時のゴムの温度は135℃であった。なお、通水路を流れる水の温度は、混練り開始後80秒までは60℃に設定してあったが、それ以降は25℃に移行させた。
【0069】
続いて、加圧シリンダー3を上げ、ロータ1a,1bの回転数を5rpmに下げてゴムの冷却を行った。冷却は150秒間行い、冷却終了時のゴムの温度は100℃であった。
【0070】
次に、混合槽2の開口部からイオウを投入し、再び加圧1シリンダー14を下げ、ロータ1a,1bの回転数を20rpmとして加硫剤のミキシングを行った。加硫剤のミキシングは60秒間行った。なお、ミキシング開始後40秒後に、加圧シリンダー3を一旦上げ、すぐに下げるという操作を行った。このときゴムは、加圧シリンダー3と共に一旦上方に上がり、そしてロータ1a,1bによって下方に引き戻されるという挙動を示した。
【0071】
最後に練り上がった未加硫天然ゴム組成物を混合槽2から取り出した。このときゴムの温度は95℃であった。
【0072】
【その他の実施の形態】
上記実施形態においては、ゴム練り機として噛み合い式ニーダーが用いられているが、特にこれに限定されるものではなく、ロールミキサー、バンバリーミキサー等であってもよい。
【0073】
また、本発明の適用例として天然ゴムの例とニトリルゴムと塩化ビニルの混合物の例を挙げたが、本発明に係る未加硫ゴム組成物の製造方法は、特にこれらのゴム種に限定されるものではなく、クロロプレンゴム(CR)、アクリルゴム(ACM)、エチレン−プロピレンゴム(EPDM)等の単独種のゴム、2種以上のゴムの混合物、ゴムと他のポリマーとの混合物等であっても適用できるものである。
【図面の簡単な説明】
【図1】 噛み合い式ニーダーのゴム練り部断面図。
【図2】 噛み合い式ニーダーの制御機構を表す図。
【図3】 本発明に係る未加硫ゴム組成物の製造方法における工程順序を表す図。
【図4】 本発明の適用例1の工程図。
【図5】 本発明の適用例2の工程図。
【符号の説明】
1a ロータ
1b ロータ
2 混合槽
3 加圧シリンダー
21 温度センサー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an unvulcanized rubber composition used for processing rubber products.
[0002]
[Prior art]
Generally, an unvulcanized rubber composition used for processing rubber products is manufactured through the following three rubber kneading steps (here, “step” refers to charging rubber into a rubber kneader, rubber kneading, This means the concept including taking out the kneaded rubber from the rubber kneader.
[0003]
First, a raw rubber not containing a rubber compound is kneaded alone with a rubber kneader. This rubber kneading step is called a mastication step, whereby the molecular chains of the raw rubber are cut, and the lengths of the molecular chains are averaged. In addition, the elasticity of the raw rubber is reduced and plasticization is enhanced, and the subsequent rubber kneading processability is improved. Secondly, a rubber compounding agent such as carbon black, plasticizer (oil), stearic acid, and anti-aging agent is added to the raw rubber that has been masticated, and the whole is kneaded with a rubber kneader. This rubber kneading step is called a kneading step, and these rubber compounding agents are mixed with the raw rubber to increase the strength of the rubber product after vulcanization, improve the rubber kneading processability, Effects such as prevention of rubber deterioration caused by radicals generated by cutting can be obtained. Third, the required amount of vulcanizing agent is added to the kneaded rubber compound and the whole is kneaded. This rubber kneading step is called a vulcanizing agent mixing step. The vulcanizing agent reacts with the rubber molecules to form a bridge structure between the rubber molecules to form a three-dimensional network of the molecules, thereby imparting rubber elasticity.
[0004]
These three rubber kneading steps are not performed continuously, but intermittently and using a plurality of types of rubber kneaders. For example, after kneading with a Banbury mixer, kneading is performed with a kneader, and further vulcanizing agent mixing is performed with a roll mixer.
[0005]
[Problems to be solved by the invention]
However, the conventional method for producing an unvulcanized rubber in which each rubber kneading step is independent has the following problems.
[0006]
First, since the same operation accompanying rubber kneading, such as charging and unloading of rubber, is repeatedly performed for each rubber kneading step, there is a problem that the efficiency of the entire rubber kneading step is poor.
[0007]
Also, in each rubber kneading step, heat is applied to the rubber to improve rubber kneading processability. However, if each rubber kneading step is performed intermittently, the temperature of the rubber once rises in the mastication step. Even so, the rubber is cooled in the process of transferring the rubber from the kneading rubber kneader to the kneading rubber kneading machine, and it is necessary to reheat the rubber in the kneading step. Similarly, even if the temperature of the rubber once rises in the kneading step, the temperature of the rubber may have dropped more than necessary in the stage of the vulcanizing agent mixing step, and at that time, it is necessary to apply heat to the rubber again. . Therefore, as a whole rubber kneading step, there is an inconvenience that wasteful energy is consumed to raise the temperature of the rubber.
[0008]
Further, when a different rubber kneader is used for each rubber kneading step, there is a problem that a space for installing a plurality of types of rubber kneaders needs to be secured in the factory.
[0009]
And as mentioned above, since the working efficiency of the rubber kneading step is poor and energy is wasted, there is also a disadvantage that the cost required for producing the unvulcanized rubber becomes high.
[0010]
The present invention has been made in view of the above points, and its object is to perform three rubber kneading steps of mastication, kneading, and vulcanizing agent mixing in a single rubber kneader. This is to save labor, save space, save energy and reduce costs in the production of unvulcanized rubber.
[0011]
[Means for Solving the Problems]
The present invention is a method for producing unvulcanized rubber, in which three kneading steps of mastication, kneading and vulcanizing agent mixing are continuously performed in the same mixing tank of one rubber kneader. is there.
[0012]
Specifically, the invention of claim 1 is a method for producing an unvulcanized rubber composition used for processing rubber products,
The raw rubber containing no rubber compounding agents, provided with a mixing vessel having a pair of rotors, the mixing tank of the rubber mill a meshing type mixer water passage flowing water for temperature control of the mixing vessel is provided The raw rubber input process to be input to
A kneading step of kneading the raw rubber in the mixing tank of the rubber kneader;
A rubber compounding agent adding step of adding a rubber compounding agent mixed with the kneaded raw material rubber after the mastication step into the mixing tank of the rubber kneader, excluding the vulcanizing agent ,
And said rubber compounding agents except the vulcanizing agent and the mastication already raw rubber after the mastication step, and kneading mixing in the mixing tank of the rubber kneading machine,
Cooling step of lowering the temperature of the kneaded rubber composition after the kneading step by lowering the temperature of the water flowing through the water passage and rotating the pair of rotors in the mixing tank of the rubber kneader When,
A vulcanizing agent charging step of charging the vulcanizing agent to be mixed with the kneaded rubber composition after the cooling step into the mixing tank of the rubber kneader ;
And said vulcanizing agent and said kneading been rubber composition after the cooling step, the vulcanizing agent mixing step of mixing within the mixing tank of the rubber kneading machine,
With
A method for producing unvulcanized rubber composition which is characterized in that all these steps in the same the same the mixing chamber of the rubber mill.
[0013]
In the above-described method for producing an unvulcanized rubber composition, raw material rubber not containing a rubber compounding agent, mastication, rubber compounding agent excluding vulcanizing agent, kneading, cooling, vulcanizing agent charging and vulcanization Since each step of the agent mixing is continuously performed in the same mixing tank of one rubber kneader, it is not necessary to perform loading and unloading of rubber at each rubber kneading step. Therefore, rationalization and labor saving of rubber kneading work can be achieved.
[0014]
Also, after the mastication process, the rubber compounding agent excluding the vulcanizing agent is added, and then the process proceeds to the kneading process. After the kneading process, the rubber is cooled and the vulcanizing agent is added, and then the process proceeds to vulcanizing agent mixing. . That is, the rubber moves to a kneading process or a vulcanizing agent mixing process in a state where the temperature has risen to some extent, and there is no need for heating to compensate for the temperature decrease as in the prior art. Therefore, energy saving can be achieved as a whole rubber kneading step.
[0015]
In addition, it is not necessary to install multiple types of rubber kneaders, since it is possible to carry out everything from the introduction of rubber containing no rubber compounding agent to the mixing of vulcanizing agents in the same mixing tank of one rubber kneader. Space can be saved.
[0016]
And the cost reduction can be aimed at as a whole rubber kneading step resulting from rationalization, labor saving, and energy saving of said rubber kneading step.
[0017]
In addition, if the heat generated by the deformation of the rubber is large in the vulcanizing agent mixing process, the vulcanization of the rubber proceeds in this process.
[0018]
Further, even when the time of the vulcanizing agent mixing process is prolonged, the rubber is given a temperature history at a high temperature, which causes the rubber to progress in vulcanization. Therefore, it is preferable that the vulcanizing agent can be mixed in as short a time as possible.
[0019]
Further, as rubber types to which the present method for producing an unvulcanized rubber composition can be applied, natural rubber, chloroprene rubber (CR), nitrile rubber (NBR), acrylic rubber (ACM), ethylene-propylene rubber (EPDM), etc. Specific examples of the rubber include a single type of rubber, a mixture of two or more types of rubber, and a mixture of rubber and another polymer. From the viewpoint of preventing the rubber from progressing in the vulcanizing agent mixing step, the specific heat Is particularly preferable for application to natural rubber, chloroprene rubber (CR), and nitrile rubber (NBR) that are small and easy to cool.
[0020]
In the raw rubber charging process, the rotor in the mixing tank of the rubber kneader may be stopped and the raw rubber may be charged. However, in that case, a high torque is required when the rotor is driven, which may cause a failure of the rubber kneader. Therefore, it is preferable to feed the raw rubber while rotating the rotor in the mixing tank of the rubber kneader.
[0021]
The temperature of the rubber in the mastication step is preferably 130 ± 20 ° C. from the viewpoint of balancing rubber kneadability and prevention of rubber thermal degradation.
[0022]
In the compounding step, the rotor in the mixing tank of the rubber kneader may be stopped and the rubber compounding agent may be charged, but in order to quickly disperse the rubber compounding agent sequentially added to the rubber, Subsequently, it is preferable to add the rubber compounding agent while kneading the rubber.
[0023]
The temperature of the rubber in the kneading step is preferably 130 ± 20 ° C. from the viewpoint of balancing rubber kneadability and prevention of thermal deterioration of the rubber, as in the kneading step.
[0024]
Cooling step after the kneading step is completed, in order to lower the temperature of the entire rubber quickly, cool the rubber while rotating the rotor in the mixing vessel a rubber mill at low speed. Further, after the rubber composition is made uniform at the end of the kneading process, cooling of the rubber may be started while rotating the rotor in the mixing tank of the rubber kneader.
[0025]
In the vulcanizing agent charging process, the rotor in the mixing tank of the rubber kneader may be stopped and the vulcanizing agent may be charged, but in order to disperse the vulcanizing agent quickly in the rubber, the mixing of the rubber kneader It is preferable to add the vulcanizing agent while rotating the rotor in the tank .
[0026]
The temperature of the rubber in the vulcanizing agent mixing step is preferably 95 ± 10 ° C. from the viewpoint of balancing rubber kneadability and prevention of rubber vulcanization.
[0027]
In addition, since the rubber kneader is an intermeshing mixer having excellent cooling efficiency, the rubber is quickly cooled when moving from the kneading process to the vulcanizing agent mixing process, and in the vulcanizing agent mixing process, the rubber is mixed. The progress of vulcanization can be effectively prevented. Here, the meshing mixer means a meshing Banbury mixer or a meshing kneader.
[0028]
According to a second aspect of the invention, a manufacturing method of claim 1 or claim 2 unvulcanized rubber composition according,
In the raw material rubber-on process, put the shut solution agent together with the raw rubber which does not contain the rubber compounding agent to the mixing tank of the rubber kneading machine,
In the mastication process, a manufacturing method of the unvulcanized rubber composition which is characterized by masticating with shut solution agent the raw rubber not including the rubber compounding agent.
[0029]
In such a method for producing an unvulcanized rubber composition, since the raw rubber is masticated together with the crushing agent, the viscosity of the raw rubber is lowered and the masticability can be improved. Therefore, the raw rubber is uniformly kneaded as a whole, and a kneaded rubber with no variation in quality can be obtained. Examples of the demulcent include di- (benzamidophenyl) disulfide. The shattering agent is added for the purpose of reducing the viscosity of the raw rubber, and is different from the rubber compounding agent.
[0030]
【The invention's effect】
As described above, according to the invention described in claim 1, the raw material rubber not containing the rubber compounding agent is added, masticated, the rubber compounding agent excluding the vulcanizing agent is added, kneaded, cooled, and the vulcanizing agent is added. Each step of charging and taking out the vulcanizing agent mixing is continuously performed in the same kneading tank of one rubber kneader , so that the rubber kneading step can be rationalized and labor-saving. In addition, since it is not necessary to perform heating to compensate for the decrease in the temperature of the rubber in the kneading step and the vulcanizing agent mixing step, energy saving can be achieved as a whole rubber kneading step. In addition, it is not necessary to install multiple types of rubber kneaders in the same kneading tank of a single rubber kneader , from the introduction of rubber containing no rubber compounding agents to the mixing of vulcanizing agents. Space can be achieved. Further, labor saving, rationalization and energy saving of the rubber kneading step can be achieved, so that the cost of the rubber kneading step as a whole can be reduced. In addition, since the rubber kneader is an intermeshing mixer, the kneaded rubber can be quickly cooled and the progress of vulcanization of the rubber in the vulcanizing agent mixing step can be effectively prevented.
[0031]
Furthermore, according to the second aspect of the invention, in addition to the effects of the invention of claim 2 or claim 3, wherein, since the raw rubber is masticated with shut solution agent improves the processability of mastication, It is possible to stabilize the quality of crushed rubber.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method of the unvulcanized rubber which used the meshing type kneader as embodiment of this invention is demonstrated in detail based on drawing.
[0033]
<Intermeshing kneader>
FIG. 1 shows a rubber kneaded section of an intermeshing kneader used in the method for producing an unvulcanized rubber composition according to the present invention. The rubber kneading part of the meshing kneader is composed of a pair of rotors 1 a and 1 b, a mixing tank 2 and a pressure cylinder 3.
[0034]
The pair of rotors 1 a and 1 b are installed in parallel in the mixing tank 2. When the rubber is placed on the upper part between the rotors 1a and 1b, the rotors 1a and 1b rotate in directions opposite to each other in the direction of pushing the rubber downward. Further, the blade trajectory of the rotor 1a and the blade trajectory of the rotor 1b have overlapping portions in the vicinity of the center between the axes of the rotors 1a and 1b. However, the rotors 1a and 1b always form a gap between them and rotate without contacting each other. And when rubber | gum passes through this clearance gap, shear deformation will be added to rubber | gum and rubber | gum will be kneaded.
[0035]
The mixing tank 2 surrounds the rotors 1a and 1b, and rubber is kneaded inside the mixing tank 2. Further, when the rubber passes through the gap between the inner wall of the mixing tank 2 and the rotors 1a and 1b, the rubber is subjected to shear deformation and the rubber is kneaded. The mixing tank 2 is provided with a temperature sensor 21 for detecting the temperature of the rubber.
[0036]
The pressure cylinder 3 serves as a lid for the mixing tank 2. When the pressure cylinder 3 is raised and the mixing tank 2 is opened, the opening is an inlet for raw rubber, a rubber compounding agent, and a vulcanizing agent. When the pressure cylinder 3 descends and closes, the opening of the mixing tank 2 is sealed to prevent scattering of the rubber compounding agent and the like. .
[0037]
The temperature adjustment inside the rubber kneading part of the meshing kneader is such that water whose temperature is adjusted by the mixing ratio of steam and cooling water is passed through the water passages provided inside the rotors 1a and 1b, the mixing tank 2 and the pressure cylinder 3. Is done.
[0038]
FIG. 2 is a diagram showing a control mechanism of the meshing kneader. A temperature sensor 21 is attached to the mixing tank 2 of the rubber kneading part, and this senses the temperature of the rubber being kneaded. Subsequently, it is converted into an electrical signal and input to the controller. <Rubber kneading step>
FIG. 3 shows a process sequence in the method for producing an unvulcanized rubber composition.
[0039]
First, a raw rubber charging process. In this step, the pressure cylinder 3 is raised, the mixing tank 2 is opened, and raw rubber not containing a rubber compounding agent is introduced from the opening of the mixing tank 2 while rotating the rotors 1a and 1b. At this time, in order to lower the viscosity of the raw rubber and improve the kneading processability, a shattering agent is added together with the raw rubber.
[0040]
Next, it is a mastication process. In this step, the pressure cylinder 3 is lowered, the opening of the mixing tank 2 is sealed, and the raw rubber is kneaded by rotating the rotors 1a and 1b. The molecular chains of the raw rubber are cut by mastication, and the lengths of the molecular chains are averaged. In addition, the elasticity of the raw rubber is reduced and plasticization is enhanced, and the subsequent rubber kneading processability is improved. The temperature sensor 21 attached to the mixing tank 2 senses the temperature of the rubber, which is converted into an electrical signal and sent to the control device. Then, a signal is output to the PID controller based on the signal, and the valve in which the cooling water and the steam are connected is controlled.
[0041]
Subsequently, a rubber compounding agent charging step. In this step, the pressure cylinder 3 is raised, the mixing tank 2 is opened, and a rubber compounding agent excluding vulcanizing agents such as carbon black, stearic acid and anti-aging agent is introduced from the opening of the mixing tank 2. The rubber compounding agent is charged while the rotors 1a and 1b are rotated.
[0042]
Next, it is a kneading step. In this step, the pressure cylinder 3 is lowered, the opening of the mixing tank 2 is sealed, and the raw rubber material and the added rubber compounding agent are kneaded together by rotation of the rotors 1a and 1b. When rubber compounding agents are mixed with rubber, the strength of rubber products after vulcanization is increased, rubber kneading processability is improved, and deterioration of rubber due to radicals generated by the breaking of rubber molecular chains is prevented. Etc. are obtained. The temperature sensor 21 attached to the mixing tank 2 senses the temperature of the rubber, which is converted into an electrical signal and sent to the control device. Then, a signal is output to the PID controller based on the signal, and the valve in which the cooling water and the steam are connected is controlled. In this respect, the same control as in the mastication process is performed.
[0043]
Then, it is a cooling process. In this step, the pressure cylinder 3 is raised, the mixing tank 2 is opened, the temperature of the water passing through the water passage is lowered, and the temperature of the rubber is lowered. This is intended to prevent rubber vulcanization from proceeding at the vulcanizing agent mixing stage after the vulcanizing agent is added. Here, the temperature of the water passing through the water passage is adjusted by sending a signal from the control device to the PID controller, thereby controlling the valve and adjusting the ratio of the cooling water and the steam. If the rubber is cooled while rotating the rotors 1a and 1b at a low speed, the entire rubber is cooled uniformly, which is efficient.
[0044]
Next, a vulcanizing agent charging step. In this step, a vulcanizing agent is charged from the opening of the mixing tank 2. The vulcanizing agent is charged while the rotors 1a and 1b are rotated.
[0045]
And it is a vulcanizing agent mixing process. In this step, the pressure cylinder 3 is lowered, the opening of the mixing tank 2 is sealed, and the kneaded rubber and the added vulcanizing agent are kneaded by the rotation of the rotors 1a and 1b. This vulcanizing agent reacts with rubber molecules at a high temperature to form a bridge structure between the rubber molecules to form a three-dimensional network of molecules, and to give rubber elasticity to the rubber composition after vulcanization. The temperature sensor 21 attached to the mixing tank 2 senses the temperature of the rubber, which is converted into an electrical signal and sent to the control device. Then, a signal is output to the PID controller based on the signal, and the valve in which the cooling water and the steam are connected is controlled. In this respect, the same control as in the kneading process and the kneading process is performed.
[0046]
An unvulcanized rubber composition is manufactured by performing the above series of steps in a single meshing kneader.
[0047]
Next, operations and effects in the method for producing an unvulcanized rubber composition according to this embodiment will be described.
[0048]
In the method for producing an unvulcanized rubber composition according to the present embodiment, the raw rubber containing no rubber compounding agent is added, masticated, the rubber compounding agent excluding the vulcanizing agent is added, kneaded, cooled, and the vulcanizing agent is input. In addition, since each process of vulcanizing agent mixing is continuously performed in the same mixing tank of a single meshing kneader , it is not necessary to input and take out rubber at each rubber kneading step. Therefore, rationalization and labor saving of the rubber kneading step can be achieved.
[0049]
Also, after the mastication process, the rubber compounding agent excluding the vulcanizing agent is added, and then the process proceeds to the kneading process. After the kneading process, the rubber is cooled and the vulcanizing agent is added, and then the process proceeds to vulcanizing agent mixing. . That is, the rubber moves to a kneading process or a vulcanizing agent mixing process in a state where the temperature has risen to some extent, and heating to compensate for the temperature decrease as in the conventional case is not necessary. Therefore, energy saving can be achieved as a whole rubber kneading step.
[0050]
In addition, the same mixing tank of a single meshing kneader can be used to feed raw rubber that does not contain a rubber compounding agent to mix vulcanizing agents, so there is no need to install multiple types of rubber kneaders. Space can be saved.
[0051]
And the cost reduction can be aimed at as a whole rubber kneading step resulting from rationalization, labor saving, and energy saving of said rubber kneading step.
[0052]
In addition, since a mesh kneader with good cooling efficiency is used as a rubber kneader, the rubber is quickly cooled when moving from the kneading step to the vulcanizing agent mixing step, and in the vulcanizing agent mixing step, The progress of vulcanization can be effectively prevented.
[0053]
And since a shattering agent is thrown in with raw material rubber and masticated, the viscosity of raw material rubber can fall and it can improve the masticability of raw material rubber. Therefore, the raw rubber is uniformly kneaded as a whole, and a kneaded rubber with no variation in quality can be obtained.
[0054]
<Application example 1 of the present invention>
The example which applied said unvulcanized rubber manufacturing method to natural rubber is demonstrated. The rubber compounding is as shown in Table 1 (in the table, phr is a unit representing parts by weight of each rubber compounding agent to be added with respect to 100 parts by weight of the raw rubber).
[0055]
[Table 1]
Figure 0003665225
[0056]
The raw rubber not containing the compounding agent is natural rubber. The rubber compounding agent excluding the vulcanizing agent is a plasticizer, FEF carbon black, calcium carbonate, zinc oxide, stearic acid, wax, anti-aging agent and vulcanization accelerator. The vulcanizing agent is sulfur.
[0057]
FIG. 4 shows a process diagram of Application Example 1 of the present invention. In the figure, the horizontal direction indicates the passage of time. Further, the upper flat portion in the vertical direction indicates a state where the mixing tank 2 of the meshing kneader is closed, that is, a state where the pressure cylinder is lowered, and the lower flat portion indicates a state where the mixing tank 2 is open, That is, the pressure cylinder is in a raised state.
[0058]
First, the rotors 1a and 1b of the meshing kneader were rotated, and 0.3 phr of natural rubber and di- (benzamidophenyl) disulfide as a demulcent agent were charged from the opening of the mixing tank 2. And the pressure cylinder 3 was lowered | hung and the natural rubber was masticated. At this time, the number of rotations of the rotors 1a and 1b was set to 40 rpm, and the temperature of water flowing through the water passage was set to 60 ° C. The mastication was performed for 120 seconds, and the temperature of the rubber at the end of the mastication was 125 ° C.
[0059]
Next, the pressure cylinder 3 was raised while rotating the rotors 1 a and 1 b at 40 rpm, and a rubber compounding agent except for the vulcanizing agent was introduced from the opening of the mixing tank 2. The pressure cylinder was lowered again, and kneading was performed with the rotor 1a, 1b rotating at 40 rpm. The kneading was performed for 100 seconds, and the rubber temperature at the end of the kneading was 125 ° C. In addition, although the temperature of the water which flows through a water flow path was set to 60 degreeC until 60 second after kneading | mixing start, it was made to transfer to 25 degreeC after that.
[0060]
Subsequently, the pressure cylinder 3 was raised, and the number of rotations of the rotors 1a and 1b was lowered to 5 rpm to cool the rubber. Cooling was performed for 150 seconds, and the rubber temperature at the end of cooling was 90 ° C.
[0061]
Next, sulfur was introduced from the opening of the mixing tank 2, the pressure cylinder 3 was lowered again, and the rotational speed of the rotors 1a and 1b was set to 20 rpm to mix the vulcanizing agent. The vulcanizing agent was mixed for 60 seconds. Forty seconds after starting mixing, the pressure cylinder 3 was once raised and immediately lowered. At this time, the rubber behaved once with the pressurizing cylinder 3 and pulled back downward by the rotors 1a and 1b. Thus, the dispersibility of the rubber compounding agent including sulfur can be improved by once interrupting the steady kneading state and shifting to another steady kneading state.
[0062]
Finally, the unvulcanized natural rubber composition kneaded was taken out from the mixing tank 2. At this time, the temperature of the rubber was 95 ° C.
[0063]
<Application example 2 of the present invention>
An example in which the above unvulcanized rubber production method is applied to a mixture of nitrile rubber (NBR) and vinyl chloride (PVC) will be described. The rubber composition is as shown in Table 2.
[0064]
[Table 2]
Figure 0003665225
[0065]
The raw rubber not containing the compounding agent is a mixture of nitrile rubber (NBR) and vinyl chloride (PVC). The rubber compounding agents excluding the vulcanizing agent are liquid nitrile rubber, FEF carbon black, silica, zinc oxide, stearic acid, anti-aging agent and vulcanization accelerator. The vulcanizing agent is sulfur.
[0066]
FIG. 5 shows a process diagram of Application Example 2 of the present invention. The content of the figure is the same as in the case of FIG.
[0067]
First, the rotors 1a and 1b of the meshing kneader were rotated, and a mixture of nitrile rubber (NBR) and vinyl chloride (PVC) was charged from the opening of the mixing tank 2. The pressure cylinder 3 was lowered and the mixture of nitrile rubber (NBR) and vinyl chloride (PVC) was masticated. At this time, the number of rotations of the rotors 1a and 1b was set to 30 rpm, and the water flowing through the water passage was set to 60 ° C. The mastication was performed for 50 seconds, and the temperature of the rubber at the end of the mastication was 140 ° C.
[0068]
Next, the pressure cylinder 3 was raised, and a rubber compounding agent except for the vulcanizing agent was introduced from the opening while rotating the rotor 1a, 1b at a rotational speed of 40 rpm. The pressure cylinder was lowered again, and kneading was performed with the rotor 1a, 1b rotating at 40 rpm. The kneading was performed for 120 seconds, and the rubber temperature at the end of the kneading was 135 ° C. In addition, although the temperature of the water which flows through a water flow path was set to 60 degreeC until 80 second after kneading | mixing start, it was made to transfer to 25 degreeC after that.
[0069]
Subsequently, the pressure cylinder 3 was raised, and the number of rotations of the rotors 1a and 1b was lowered to 5 rpm to cool the rubber. Cooling was performed for 150 seconds, and the temperature of the rubber at the end of cooling was 100 ° C.
[0070]
Next, sulfur was introduced from the opening of the mixing tank 2, the pressure 1 cylinder 14 was lowered again, and the rotation speed of the rotors 1a and 1b was set to 20 rpm to mix the vulcanizing agent. The vulcanizing agent was mixed for 60 seconds. Forty seconds after starting mixing, the pressure cylinder 3 was once raised and immediately lowered. At this time, the rubber was once raised upward together with the pressurizing cylinder 3 and showed a behavior of being pulled back downward by the rotors 1a and 1b.
[0071]
Finally, the unvulcanized natural rubber composition kneaded was taken out from the mixing tank 2. At this time, the temperature of the rubber was 95 ° C.
[0072]
[Other embodiments]
In the above-described embodiment, an intermeshing kneader is used as the rubber kneader, but the invention is not particularly limited to this, and a roll mixer, a Banbury mixer, or the like may be used.
[0073]
Further, examples of application of the present invention include examples of natural rubber and mixtures of nitrile rubber and vinyl chloride. However, the method for producing an unvulcanized rubber composition according to the present invention is particularly limited to these rubber types. It is not a single type of rubber such as chloroprene rubber (CR), acrylic rubber (ACM), ethylene-propylene rubber (EPDM), a mixture of two or more types of rubber, a mixture of rubber and other polymers, etc. However, it can be applied.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a rubber kneading portion of an intermeshing kneader.
FIG. 2 is a diagram showing a control mechanism of a meshing kneader.
FIG. 3 is a diagram showing a process sequence in the method for producing an unvulcanized rubber composition according to the present invention.
FIG. 4 is a process diagram of application example 1 of the present invention.
FIG. 5 is a process diagram of an application example 2 of the present invention.
[Explanation of symbols]
1a Rotor 1b Rotor 2 Mixing tank 3 Pressure cylinder 21 Temperature sensor

Claims (2)

ゴム製品の加工に使用される未加硫ゴム組成物の製造方法であって、
ゴム配合剤を含まない原料ゴムを、一対のロータを有する混合槽を備えると共に、前記混合槽内を温度調節する水を流す通水路が設けられた噛み合い式ミキサーであるゴム練り機の前記混合槽に投入する原料ゴム投入工程と、
前記原料ゴムを前記ゴム練り機の前記混合槽内で練る素練り工程と、
前記素練り工程後の素練り済み原料ゴムに混合するゴム配合剤を、加硫剤を除いて前記ゴム練り機の前記混合槽に投入するゴム配合剤投入工程と、
前記素練り工程後の前記素練り済み原料ゴムと前記加硫剤を除く前記ゴム配合剤とを前記ゴム練り機の前記混合槽内で混合する混練り工程と、
前記混練り工程後の混練り済みゴム組成物の温度を、前記通水路に流す水の温度を下げると共に、前記ゴム練り機の前記混合槽内で前記一対のロータを回転させることにより下げる冷却工程と、
前記冷却工程後の前記混練り済みゴム組成物に混合する前記加硫剤を、前記ゴム練り機の前記混合槽に投入する加硫剤投入工程と、
前記冷却工程後の前記混練り済みゴム組成物と前記加硫剤とを前記ゴム練り機の前記混合槽内で混合する加硫剤ミキシング工程と、
を備え、
これらすべての工程を同一の前記ゴム練り機の同一の前記混合槽内において行うことを特徴とする未加硫ゴム組成物の製造方法。
A method for producing an unvulcanized rubber composition used for processing rubber products,
The raw rubber containing no rubber compounding agents, provided with a mixing vessel having a pair of rotors, the mixing tank of the rubber mill a meshing type mixer water passage flowing water for temperature control of the mixing vessel is provided The raw rubber input process to be input to
A kneading step of kneading the raw rubber in the mixing tank of the rubber kneader;
A rubber compounding agent adding step of adding a rubber compounding agent mixed with the kneaded raw material rubber after the mastication step into the mixing tank of the rubber kneader, excluding the vulcanizing agent ,
And said rubber compounding agents except the vulcanizing agent and the mastication already raw rubber after the mastication step, and kneading mixing in the mixing tank of the rubber kneading machine,
Cooling step of lowering the temperature of the kneaded rubber composition after the kneading step by lowering the temperature of the water flowing through the water passage and rotating the pair of rotors in the mixing tank of the rubber kneader When,
A vulcanizing agent charging step of charging the vulcanizing agent to be mixed with the kneaded rubber composition after the cooling step into the mixing tank of the rubber kneader ;
And said vulcanizing agent and said kneading been rubber composition after the cooling step, the vulcanizing agent mixing step of mixing within the mixing tank of the rubber kneading machine,
With
Method for producing unvulcanized rubber composition which is characterized in that all these steps in the same of the rubber mill same the mixing vessel of.
請求項1記載の未加硫ゴム組成物の製造方法であって、
前記原料ゴム投入工程において、前記ゴム配合剤を含まない前記原料ゴムとともにシャッ解剤を前記ゴム練り機の前記混合槽に投入し、
前記素練り工程において、前記ゴム配合剤を含まない前記原料ゴムをシャッ解剤とともに素練りすることを特徴とする未加硫ゴム組成物の製造方法。
A method according to claim 1 Symbol placement of the unvulcanized rubber composition,
In the raw material rubber-on process, put the shut solution agent together with the raw rubber which does not contain the rubber compounding agent to the mixing tank of the rubber kneading machine,
In the mastication method of manufacturing an unvulcanized rubber composition which is characterized by masticating with shut solution agent the raw rubber not including the rubber compounding agent.
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