JP2004300385A - Method for inhibiting polymerization of aromatic vinyl compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inhibiting polymerization of an aromatic vinyl compound by using a compound providing the effects of suppressing the polymerization at the initial time of the polymerization of the aromatic vinyl compound, and for a long time in a production, purification, storage and transportation process of the aromatic vinyl compound, and having easy treatability. <P>SOLUTION: The method for inhibiting the polymerization of the aromatic vinyl compound involves adding (A) a 2,2,6,6-tetramethylpiperidin-1-oxyl compound, (B) a 2-nitrophenol compound and (C) a sulfonic acid compound in combination in the production, purification, storage and transportation process of the aromatic vinyl compound. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１１】
【化５】

【００１２】
【化６】

【００１３】
請求項２に係わる発明は、請求項１記載の芳香族ビニル化合物の重合抑制方法であり、（Ａ）成分のピペリジン−１−オキシル化合物が２，２，６，６−テトラメチルピペリジン−１−オキシル、４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−オキソ−２，２，６，６−テトラメチルピペリジン−１−オキシルから選ばれる１種以上であることを特徴とする。
【００１４】
請求項３に係わる発明は、請求項１記載の芳香族ビニル化合物の重合抑制方法であり、（Ｂ）成分の２−ニトロフェノール化合物が２，４−ジニトロフェノール、２，６−ジニトロフェノール、２，６−ジニトロ−４−メチルフェノール、２，４−ジニトロ−６−第二ブチルフェノールから選ばれる１種以上であることを特徴としている。
【００１５】
請求項４に係わる発明は、請求項１記載の芳香族ビニル化合物の重合抑制方法であり、（Ｃ）成分のスルホン酸化合物がトルエンスルホン酸、キシレンスルホン酸、クメンスルホン酸、ドデシルベンゼンスルホン酸、ペンタデシルベンゼンスルホン酸、ジノニルナフタレンスルホン酸から選ばれる１種以上であることを特徴としている。
【００１６】
請求項５に係る発明は、請求項１乃至４のいずれか記載の芳香族ビニル化合物の重合抑制方法であり、前記（Ａ）成分と（Ｂ）成分を重量比で２：９８〜３３：６７、かつ（Ａ）成分と（Ｂ）成分の合計量と（Ｃ）成分を重量比で９９：１〜１：９９で添加することを特徴としている。
【００１７】
【発明の実施の形態】
以下、本発明について詳細に説明する。
本発明は、芳香族ビニル化合物の製造、精製、貯蔵、あるいは輸送工程における芳香族ビニル化合物の重合抑制方法および重合によって生じる汚れの防止を効果的に達成し得る重合抑制方法であり、（Ａ）ピペリジン−１−オキシル化合物（以下、「（Ａ）成分」とする。）と、（Ｂ）２−ニトロフェノール化合物（以下、「（Ｂ）成分」とする。）と、（Ｃ）スルホン酸化合物（以下、「（Ｃ）成分」とする。）を組み合わせて、該芳香族ビニル化合物に添加することにより、それぞれ単独よりも少量の合計添加量で、初期の重合が開始するまでの時間を遅くする効果と重合速度を低く維持する効果のいずれをも向上させることに特徴がある。
【００１８】
本発明における芳香族ビニル化合物は、スチレン、メチルスチレン、エチルスチレン、ジビニルベンゼンなどである。
【００１９】
本発明における（Ａ）成分のピペリジン−１−オキシル化合物は、前記一般式（１）で表されるＮ−置換−２，２，６，６−テトラメチルピペリジン−１−オキシル化合物である。式中のＸは水素原子、酸素原子、水酸基、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のカルボン酸基又は炭素数１〜３のアミド基である。炭素数１〜３のアルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基があり、炭素数１〜３のアルコキシ基としてはメトキシ基、エトキシ基、プロポキシ基、イソプロポキシ基があり、炭素数１〜３のカルボン酸基としては蟻酸基、酢酸基、プロピオン酸基があり、炭素数１〜３のアミド基としては蟻酸アミド基、酢酸アミド基、プロピオン酸アミド基がある。具体的には、２，２，６，６−テトラメチルピペリジン−１−オキシル、４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−オキソ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−メトキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−エトキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−カルボキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−カルバモイル−２，２，６，６−テトラメチルピペリジン−１−オキシル等が挙げられ、好ましくは２，２，６，６−テトラメチルピペリジン−１−オキシル、４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル、４−オキソ−２，２，６，６−テトラメチルピペリジン−１−オキシルである。これらのピペリジン−１−オキシル化合物はプロセスの状況に合わせてその１種類をあるいは２種類以上を組み合わせて使用する。
【００２０】
本発明における（Ｂ）成分の２−ニトロフェノール化合物は、前記一般式（２）で表されるように、ベンゼン環に結合したヒドロキシル基とニトロ基がオルト位の位置関係にある２−ニトロフェノール化合物である。式中のＡ、Ｂ、Ｃ、Ｄはそれぞれ独立に水素原子、ニトロ基、カルボキシル基、ヒドロキシル基、炭素数１〜１２の直鎖もしくは分岐のアルキル基を示す。具体的には、２，４−ジニトロフェノール、２，６−ジニトロフェノール、２，４−ジニトロ−６−メチルフェノール、２，６−ジニトロ−４−メチルフェノール、２，４−ジニトロ−６−第二ブチルフェノール、２，６−ジニトロ−４−第二ブチルフェノール等があり、好ましくは２，４−ジニトロフェノール、２，６−ジニトロフェノール、２，６−ジニトロ−４−メチルフェノール、２，４−ジニトロ−６−第二ブチルフェノールである。これらから１種ないし２種以上が用いられる。
【００２１】
本発明における（Ｃ）成分のスルホン酸化合物は、前記一般式（３）で表され、式中、Ｒはヒドロキシル基、炭素数１〜３２のアルキル基、少なくとも１つの炭素数１〜３２の直鎖もしくは分岐のアルキル基を持つアルキルフェニル基あるいはアルキルナフチル基である。具体的には、硫酸、トルエンスルホン酸、キシレンスルホン酸、クメンスルホン酸、ドデシルベンゼンスルホン酸、ペンタデシルベンゼンスルホン酸、ジノニルナフタレンスルホン酸などであり、これらから１種ないし２種以上が用いられる。本発明におけるスルホン酸化合物は遊離のスルホン酸化合物であり、ナトリウムやカリウム等のアルカリ金属塩、カルシウムやマグネシウム等のアルカリ土類金属塩、アミン塩やアンモニウム塩では本発明の効果を得ることはできない。
【００２２】
一般に重合抑制効果には、重合は起こるがその重合速度を低く抑え、さらにその重合速度の増加も抑える方法の重合抑制タイプと、特定期間内の重合をほとんど起こらないようにする方法の重合禁止タイプがある。重合抑制効果を厳密に区分することはできないが、一般に本発明における（Ａ）成分のピペリジン−１−オキシル化合物は重合禁止タイプの傾向が強く、（Ｂ）成分の２−ニトロフェノール化合物は重合抑制タイプの傾向が強いと考えられる。また、（Ｃ）成分のスルホン酸化合物は、一般に重合禁止タイプと考えられているが、従来から重合抑制剤と使用されることはほとんど無い。重合禁止タイプは、初期の重合抑制に優れるが、時間を経て系内のラジカルと反応して消耗すると、それ以後は実質的に重合抑制効果がなくなる。一方、重合抑制タイプは、初期の重合抑制に劣るものの比較的長時間にわたり重合を抑制することができる。
【００２３】
本発明における３種の化合物は作用機構が異なる重合抑制機能を有し、これらを組合せることによりそれぞれ単独に用いたときに見られなかった重合禁止効果および重合抑制効果がともに向上した重合抑制効果を発揮する。
【００２４】
本発明における（Ａ）成分と（Ｂ）成分、（Ｃ）成分の組合せ比率は、目的とする芳香族ビニル化合物の種類、量、運転状況および重合抑制効果の要求の程度により一律に決められるものでなく、適宜決定されれば良い。通常、重量比で（Ａ）成分と（Ｂ）成分を２：９８〜３３：６７、好ましくは５：９５〜２５：７５、かつ（Ａ）成分と（Ｂ）成分の合計量と（Ｃ）成分を重量比で９９：１〜１：９９、好ましくは９５：１〜５０：５０である。
【００２５】
本発明の重合抑制方法における（Ａ）成分、（Ｂ）成分と（Ｃ）成分の工程への添加量は、目的とする芳香族ビニル化合物の種類、量、運転状況および重合抑制効果の要求の程度により一律に決められるものでなく、適宜決定されれば良く、通常、（Ａ）成分では１〜１，０００（ｍｇ／芳香族ビニル化合物−ｋｇ）であり、好ましくは５〜５００（ｍｇ／芳香族ビニル化合物−ｋｇ）である。また、（Ｂ）成分では１０〜２，０００（ｍｇ／芳香族ビニル化合物−ｋｇ）、好ましくは５０〜１，０００（ｍｇ／芳香族ビニル化合物−ｋｇ）であり、（Ｃ）成分では１〜１，０００（ｍｇ／芳香族ビニル化合物−ｋｇ）、好ましくは５〜５００（ｍｇ／芳香族ビニル化合物−ｋｇ）である。これらの添加量の範囲は、対象とする芳香族ビニル化合物の重合抑制効果を発揮する範囲として見出したものであり、この範囲より添加量より少ないと本発明の効果が十分に得られない場合があり、この範囲より添加量より多いと重合抑制の効果は充分あるが、添加量の割には重合抑制効果の向上が顕著でなく、コストパフォーマンスが小さくなる場合がある。
【００２６】
上記各成分の添加量、組合せ比率は、工程の状況、要求度に応じて決められるべきものであり、長期間にわたり、重合を抑制したい場合には重合抑制タイプである（Ａ）成分と（Ｂ）成分を多く用い、初期の重合を完全に防止したい場合は重合禁止タイプである（Ａ）成分を多く用いるなど、適宜選択して決定すれば良い。
【００２７】
本発明における（Ａ）成分、（Ｂ）成分、（Ｃ）成分の添加箇所、添加方法は、本発明で限定されるものではないが、芳香族ビニル化合物が重合してファウリングとして問題化する箇所より上流部に添加されればよい。例えば、スチレンは一般にエチルベンゼンの脱水素反応によって製造され、生成したスチレンと未反応エチルベンゼンを連続的に蒸留分離していることから、そのエチルベンゼン脱水素後の蒸留塔群に供給するのがよい。添加方法は、ある特定箇所に一括添加してもよく、あるいはいくつかの箇所に分けて分散添加してもよい。また、（Ａ）成分、（Ｂ）成分、（Ｃ）成分はそれぞれ別々に添加することもできるが、予め適正な混合比で混合し、そのプロセス流体と同じ液体、例えばスチレンの場合にはエチルベンゼンに溶解して添加しても良い。
【００２８】
本発明の効果を妨げない範囲において、従来使用されてきた公知の重合抑制剤を併せて用いることになんら制限を加えるものではない。
【００２９】
【実施例】
以下実施例によって、本発明をさらに詳細に説明するが、本発明は以下の実施例に限定されるものではない。
【００３０】
（ピペリジン−１−オキシル化合物）
・Ｈ−ＴＥＭＰＯ：４−ヒドロキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル
・Ｏ−ＴＥＭＰＯ：４−オキソ−２，２，６，６−テトラメチルピペリジン−１−オキシル
・Ｍ−ＴＥＭＰＯ：４−メトキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル
【００３１】
（２−ニトロフェノール化合物）
・ＤＮＢＰ：２，４−ジニトロ−６−第二ブチルフェノール
・ＤＮＰ：２，４−ジニトロフェノール
・ＤＮＯＣ：２，４−ジニトロ−６−メチルフェノール
【００３２】
（スルホン酸化合物）
・ＰＴＳ：パラトルエンスルホン酸
・ＸＳＡ：キシレンスルホン酸
・ＣＳＡ：クメンスルホン酸
・ＤＤＢＳＡ：ドデシルベンゼンスルホン酸
・ＰＤＢＳＡ：ペンタデシルベンゼンスルホン酸
・ＤＮＮＳＡ：ジノニルナフタレンスルホン酸
【００３３】
（重合抑制試験１）
還流冷却器を備えた４つ口セパラブルフラスコに予めアルカリ洗浄して重合抑制剤を除いたスチレンモノマー（ＳＭ）１００ｇを入れ、所定量のピペリジン−１−オキシル化合物、２−ニトロフェノール化合物、有機スルホン酸化合物を加えて、高純度窒素ガスを３０分間吹き込んで溶存酸素を除いた。次いで１１５℃に保持し、一定時間毎に内容物の一部を取り出し、９倍容量のメタノールを加え、析出したポリマーを分離させ、予めメタノール洗浄後１０５℃にて２時間乾燥した既知重量のメンブランフィルター（孔径が１μｍ）を用いて吸引ろ過し、生成したポリマーをフィルター上に分離した。フィルターをメタノールで３回洗浄後、１０５℃にて２時間乾燥し、その重量を測定し、スチレンモノマー（ＳＭ）１００ｇ中のポリマー生成率（重量％）を求めた。結果を表１、２に示した。
【００３４】
【表１】

【００３５】
【表２】

【００３６】
本発明の方法により、スチレンを１１５℃に保持開始してから９０分後におけるポリマー生成率は０（重量％）となり、初期重合抑制性が大きく向上している。また、２７０〜３６０分後におけるポリマー生成率も低下し、本発明の方法により長時間にわたる重合抑制効果の持続性の向上も得られることがわかる。
【００３７】
（重合抑制試験２）
重合抑制試験１と同様にして、スチレンに代えてメチルスチレン（ＭＳ）を用い、保持温度を１１０℃として重合抑制試験を行った。結果を表３に示す。
【００３８】
【表３】

【００３９】
（重合抑制試験３）
重合抑制試験１と同様にして、スチレンに代えてジビニルベンゼン（ＤＶＢ）を用い、保持温度を１１０℃として重合抑制試験を行った。結果を表４に示す。
【００４０】
【表４】

【００４１】
この結果から、メチルスチレン（ＭＳ）およびジビニルベンゼン（ＤＶＢ）のいずれの場合でも、本発明の方法により、３０分後〜６０分後のポリマー生成率を０重量％に抑え、初期重合抑制が向上していることがわかる。また、１８０分後のポリマー生成率も低下し、長時間にわたり重合抑制効果の持続性向上も得られることがわかる。
【００４２】
【発明の効果】
芳香族ビニル化合物の製造、精製、貯蔵或いは輸送工程において、本発明の重合抑制方法を用いることによって、芳香族ビニル化合物あるいはこれを含有するプロセス流体の重合を抑制し、かつその効果が長く持続し、関連装置内のファウリング（汚れ）発生量を少なくすることができる。これは、関連設備の長期安定運転を可能にし、安全運転にも大きく寄与する。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for suppressing polymerization in a process fluid containing an aromatic vinyl compound in a process for producing, purifying, storing or transporting the aromatic vinyl compound.
[0002]
[Prior art]
Aromatic vinyl compounds, especially styrene, are very important compounds in industry as raw materials for polystyrene, synthetic rubber, ABS resin and the like, and are produced in large quantities. Generally, an aromatic vinyl compound is extremely easily polymerized, and is polymerized by heat or the like in a production process or a purification process thereof, thereby lowering the yield of the aromatic vinyl compound. Further, in the process equipment and related equipment for handling the aromatic vinyl compound, fouling (dirt) occurs due to polymerization of the aromatic vinyl compound, which not only hinders operation but also is not preferable in terms of work safety.
[0003]
Therefore, various polymerization inhibitors and polymerization suppression methods have been conventionally proposed and implemented. For example, a method for suppressing polymerization by phenol compounds, nitrosophenol compounds, and nitrophenol compounds (for example, see Patent Document 1), a method for suppressing initial polymerization of an aromatic vinyl compound using a piperidine-1-oxyl compound (for example, Patent Reference 2), a method using a piperidine-1-oxyl compound and a nitrophenol compound in combination (for example, see Patent Document 3), a method using a combination of alkylsulfonic acid and dialkylhydroxylamine (for example, see Patent Document 4), phenol A method of suppressing viscosity increase in an olefin production process by adding a polymerization inhibitor, an amine polymerization inhibitor, a nitroso polymerization inhibitor, and dodecylbenzenesulfonic acid or a salt thereof (for example, see Patent Document 5), a quinone-based Or a hydroquinone-based polymerization inhibitor, Inhibitor, phenylenediamine-based polymerization inhibitor and a sulfonic acid compound such as dodecylbenzenesulfonic acid and fouling prevention method of the process of handling the vinyl compound and adding the salt (e.g., Patent Document 6 reference), and the like.
[0004]
In general, it is not possible to strictly classify polymerization inhibition. However, polymerization occurs, but its polymerization rate and its increase are kept low for a long period of time. Polymerization) is a method typified by a piperidine-1-oxyl compound. Among them, the former method is often used, and 2,4-dinitrophenol (DNP) and 2,4-dinitrophenol-6-second butylphenol (DNBP) are often used as nitrophenol compounds. However, since these nitrophenol compounds correspond to poisons, strict handling is required for their handling, and reduction measures have been strongly desired. The present inventors have previously found that the combination of a nitrophenol compound and a sulfonic acid compound improves the polymerization inhibitory effect of the nitrophenol compound, and reduces the amount of the nitrophenol compound added while maintaining the polymerization inhibitory effect. (See Patent Document 7).
[0005]
However, as a method of suppressing polymerization, a method of not only suppressing the initial polymerization but also suppressing the polymerization rate over a long period of time is strongly desired, but a satisfactory method has not yet been found.
[0006]
[Patent Document 1]
JP-A-63-316745 [Patent Document 2]
JP-A-1-165534 [Patent Document 3]
JP-A-6-166636 [Patent Document 4]
US Patent No. 4,654,450 [Patent Document 5]
JP-A-7-166152 [Patent Document 6]
JP-A-8-34748 [Patent Document 7]
JP 2003-12708 A
[Problems to be solved by the invention]
An object of the present invention relates to an improvement in a polymerization suppressing method by using a nitrophenol compound and a sulfonic acid compound in combination, which is an invention described in JP-A-2003-12708. An object of the present invention is to provide a polymerization suppressing method for improving the initial polymerization suppressing effect of the above, and obtaining a longer-time polymerization suppression.
[0008]
[Means for Solving the Problems]
The present inventors have studied the characteristics of the polymerization reaction of the aromatic vinyl compound in detail, and found that by using a piperidine-1-oxyl compound, a 2-nitrophenol compound and a sulfonic acid compound in combination, the initial polymerization suppression effect was improved. The present inventors have found that the polymerization suppressing effect is effective for improving the sustainability, and have accomplished the present invention.
[0009]
That is, the invention according to claim 1 is a method for suppressing the polymerization of an aromatic vinyl compound. In the production, purification, storage, or transportation step of the aromatic vinyl compound, (A) the general formula (1) (where X is A hydrogen atom, an oxygen atom, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a carboxylic acid having 1 to 3 carbon atoms, or an amide group having 1 to 3 carbon atoms.) 2,2,6,6-tetramethylpiperidine-1-oxyl compound and (B) a compound of the general formula (2) (where A, B, C and D each independently represent a hydrogen, a nitro group, a carboxyl group, A 2-nitrophenol compound represented by a hydroxyl group, a linear or branched alkyl group having 1 to 12 carbon atoms) and (C) a general formula (3) (where R represents a hydroxyl group and a carbon number 1-32 alkyl groups, at least 1 Consists adding linear or alkylphenyl group or an alkyl showing a naphthyl group.) Sulfonic acid compound represented by having a branched alkyl group having 1 to 32 carbon atoms.
[0010]
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[0011]
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[0012]
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[0013]
The invention according to claim 2 is the method for suppressing polymerization of an aromatic vinyl compound according to claim 1, wherein the piperidine-1-oxyl compound as the component (A) is 2,2,6,6-tetramethylpiperidine-1-yl. At least one selected from oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl and 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl It is characterized.
[0014]
The invention according to claim 3 is the method for suppressing polymerization of an aromatic vinyl compound according to claim 1, wherein the 2-nitrophenol compound as the component (B) is 2,4-dinitrophenol, 2,6-dinitrophenol, , 6-dinitro-4-methylphenol and 2,4-dinitro-6-secondary butyl phenol.
[0015]
The invention according to claim 4 is the method for suppressing polymerization of an aromatic vinyl compound according to claim 1, wherein the sulfonic acid compound of the component (C) is toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, It is characterized by being at least one selected from pentadecylbenzenesulfonic acid and dinonylnaphthalenesulfonic acid.
[0016]
The invention according to claim 5 is the method for suppressing polymerization of an aromatic vinyl compound according to any one of claims 1 to 4, wherein the component (A) and the component (B) are in a weight ratio of 2:98 to 33:67. And, the total amount of the component (A) and the component (B) and the component (C) are added in a weight ratio of 99: 1 to 1:99.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The present invention relates to a method for suppressing the polymerization of an aromatic vinyl compound in the production, purification, storage, or transportation step of an aromatic vinyl compound and a method for effectively preventing the contamination caused by polymerization from occurring. Piperidine-1-oxyl compound (hereinafter, referred to as “component (A)”), (B) 2-nitrophenol compound (hereinafter, referred to as “component (B)”), and (C) sulfonic acid compound (Hereinafter, referred to as “component (C)”), and the addition to the aromatic vinyl compound can delay the time until the start of the initial polymerization with a smaller total amount of addition than the individual components. It is characterized in that both the effect of maintaining the polymerization rate and the effect of maintaining a low polymerization rate are improved.
[0018]
The aromatic vinyl compound in the present invention is styrene, methylstyrene, ethylstyrene, divinylbenzene and the like.
[0019]
The piperidine-1-oxyl compound as the component (A) in the present invention is an N-substituted-2,2,6,6-tetramethylpiperidine-1-oxyl compound represented by the general formula (1). X in the formula is a hydrogen atom, an oxygen atom, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a carboxylic acid group having 1 to 3 carbon atoms, or an amide group having 1 to 3 carbon atoms. is there. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group, and examples of the alkoxy group having 1 to 3 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. Carboxylic acid groups having 1 to 3 carbon atoms include formic acid groups, acetic acid groups, and propionic acid groups, and amide groups having 1 to 3 carbon atoms include formic acid amide groups, acetic acid amide groups, and propionic acid amide groups. Specifically, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6 , 6-Tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-1-oxyl And 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-carbamoyl-2,2,6,6-tetramethylpiperidine-1-oxyl, and the like. , 6,6-Tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethyl It is a Perijin-1-oxyl. These piperidine-1-oxyl compounds are used alone or in combination of two or more according to the situation of the process.
[0020]
The 2-nitrophenol compound as the component (B) in the present invention is, as represented by the general formula (2), a 2-nitrophenol having a hydroxyl group and a nitro group bonded to a benzene ring in an ortho-positional positional relationship. Compound. A, B, C, and D in the formula each independently represent a hydrogen atom, a nitro group, a carboxyl group, a hydroxyl group, or a linear or branched alkyl group having 1 to 12 carbon atoms. Specifically, 2,4-dinitrophenol, 2,6-dinitrophenol, 2,4-dinitro-6-methylphenol, 2,6-dinitro-4-methylphenol, 2,4-dinitro-6- Dibutylphenol, 2,6-dinitro-4-secondary butylphenol and the like, preferably 2,4-dinitrophenol, 2,6-dinitrophenol, 2,6-dinitro-4-methylphenol, 2,4-dinitrophenol -6-Second butyl phenol. One or more of these are used.
[0021]
The sulfonic acid compound as the component (C) in the present invention is represented by the above general formula (3), wherein R is a hydroxyl group, an alkyl group having 1 to 32 carbon atoms, and at least one straight chain having 1 to 32 carbon atoms. An alkylphenyl group or an alkylnaphthyl group having a chain or branched alkyl group. Specific examples include sulfuric acid, toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and one or more of these are used. . The sulfonic acid compound in the present invention is a free sulfonic acid compound, and the effects of the present invention cannot be obtained with alkali metal salts such as sodium and potassium, alkaline earth metal salts such as calcium and magnesium, amine salts and ammonium salts. .
[0022]
Generally, the polymerization suppression effect is a polymerization inhibition type in which polymerization occurs but the polymerization rate is kept low and the increase in the polymerization rate is suppressed, and a polymerization inhibition type in which polymerization is hardly caused within a specific period. There is. Although the polymerization inhibitory effect cannot be strictly classified, the piperidine-1-oxyl compound of the component (A) in the present invention generally has a strong tendency to be a polymerization-inhibited type, and the 2-nitrophenol compound of the component (B) generally has a polymerization-inhibited effect. It is considered that there is a strong tendency for type. In addition, the sulfonic acid compound as the component (C) is generally considered to be a polymerization-inhibited type, but has rarely been used as a polymerization inhibitor. The polymerization-inhibited type is excellent in suppressing the polymerization at the initial stage, but when it is consumed by reacting with the radicals in the system over time, the polymerization-suppressing effect is substantially lost thereafter. On the other hand, the polymerization inhibition type is capable of inhibiting polymerization for a relatively long time, although it is inferior to the initial polymerization inhibition.
[0023]
The three compounds of the present invention have polymerization inhibiting functions with different action mechanisms, and the combination of these compounds has improved polymerization inhibiting effect and polymerization inhibiting effect that were not observed when used alone, respectively. Demonstrate.
[0024]
In the present invention, the combination ratio of the component (A), the component (B), and the component (C) is determined uniformly according to the kind and amount of the target aromatic vinyl compound, the operating conditions, and the degree of demand for the polymerization suppressing effect. Instead, it may be determined appropriately. Usually, the components (A) and (B) are in a weight ratio of 2:98 to 33:67, preferably 5:95 to 25:75, and the total amount of the components (A) and (B) and (C) The components are in a weight ratio of 99: 1 to 1:99, preferably 95: 1 to 50:50.
[0025]
The amounts of the components (A), (B) and (C) to be added to the process in the polymerization inhibiting method of the present invention depend on the type and amount of the target aromatic vinyl compound, the operating conditions and the demand for the polymerization inhibiting effect. It is not necessarily determined uniformly according to the degree, but may be determined as appropriate. Usually, the component (A) is from 1 to 1,000 (mg / aromatic vinyl compound-kg), preferably from 5 to 500 (mg / kg). Aromatic vinyl compound-kg). The component (B) is 10 to 2,000 (mg / aromatic vinyl compound-kg), preferably 50 to 1,000 (mg / aromatic vinyl compound-kg), and the component (C) is 1 to 2,000 (mg / aromatic vinyl compound-kg). It is 1,000 (mg / aromatic vinyl compound-kg), preferably 5-500 (mg / aromatic vinyl compound-kg). The ranges of these addition amounts are found as ranges in which the effect of suppressing the polymerization of the target aromatic vinyl compound is exhibited.If the addition amount is less than this range, the effect of the present invention may not be sufficiently obtained. When the amount is larger than this range, the effect of suppressing the polymerization is sufficient, but the improvement of the effect of suppressing the polymerization is not remarkable for the added amount, and the cost performance may be reduced.
[0026]
The addition amount and combination ratio of each of the above components should be determined in accordance with the situation of the process and the degree of demand, and when it is desired to suppress polymerization for a long period of time, the components (A) and (B) which are polymerization-suppressed types are required. If it is desired to use a large amount of component and completely prevent the initial polymerization, it may be determined by appropriately selecting, for example, using a large amount of the polymerization-inhibited type (A) component.
[0027]
The location and method of addition of the components (A), (B) and (C) in the present invention are not limited by the present invention, but the aromatic vinyl compound is polymerized and causes a problem as fouling. What is necessary is just to add to an upstream part from a location. For example, styrene is generally produced by a dehydrogenation reaction of ethylbenzene, and since the produced styrene and unreacted ethylbenzene are continuously separated by distillation, it is preferable to supply the styrene to a distillation column group after the ethylbenzene is dehydrogenated. As for the method of addition, it may be added all at once to a specific location, or may be dispersedly added to several locations. The component (A), the component (B) and the component (C) can be added separately. However, they are mixed in advance at an appropriate mixing ratio, and the same liquid as the process fluid, for example, ethylbenzene in the case of styrene. May be added after dissolving in water.
[0028]
As long as the effects of the present invention are not impaired, there is no limitation on the use of conventionally known polymerization inhibitors.
[0029]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.
[0030]
(Piperidine-1-oxyl compound)
H-TEMPO: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl O-TEMPO: 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl.M -TEMPO: 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl
(2-nitrophenol compound)
DNBP: 2,4-dinitro-6-second butylphenol DNP: 2,4-dinitrophenol DNOC: 2,4-dinitro-6-methylphenol
(Sulfonic acid compound)
PTS: paratoluenesulfonic acid XSA: xylenesulfonic acid CSA: cumenesulfonic acid DDBSA: dodecylbenzenesulfonic acid PDBSA: pentadecylbenzenesulfonic acid DNNSA: dinonylnaphthalenesulfonic acid
(Polymerization inhibition test 1)
A 4-neck separable flask equipped with a reflux condenser was charged with 100 g of a styrene monomer (SM) previously washed with an alkali and excluding a polymerization inhibitor, and a predetermined amount of a piperidine-1-oxyl compound, a 2-nitrophenol compound, and an organic solvent. A sulfonic acid compound was added, and high-purity nitrogen gas was blown for 30 minutes to remove dissolved oxygen. Then, the content was kept at 115 ° C., a part of the content was taken out at regular intervals, 9 times the volume of methanol was added, the precipitated polymer was separated, and the membrane was washed with methanol and dried at 105 ° C. for 2 hours to obtain a known weight membrane. Suction filtration was performed using a filter (pore size: 1 μm), and the produced polymer was separated on the filter. After washing the filter three times with methanol, the filter was dried at 105 ° C. for 2 hours, and its weight was measured to determine the polymer formation rate (% by weight) in 100 g of styrene monomer (SM). The results are shown in Tables 1 and 2.
[0034]
[Table 1]

[0035]
[Table 2]

[0036]
According to the method of the present invention, the polymer generation rate after 90 minutes from the start of holding styrene at 115 ° C. is 0 (% by weight), and the initial polymerization inhibition is greatly improved. In addition, the polymer formation rate after 270 to 360 minutes is also reduced, and it can be seen that the method of the present invention can also improve the sustainability of the polymerization inhibition effect over a long period of time.
[0037]
(Polymerization inhibition test 2)
In the same manner as in Polymerization Inhibition Test 1, a polymerization inhibition test was performed using methylstyrene (MS) instead of styrene at a holding temperature of 110 ° C. Table 3 shows the results.
[0038]
[Table 3]

[0039]
(Polymerization inhibition test 3)
In the same manner as in the polymerization suppression test 1, divinylbenzene (DVB) was used in place of styrene, and the polymerization suppression test was performed at a holding temperature of 110 ° C. Table 4 shows the results.
[0040]
[Table 4]

[0041]
From these results, in any case of methylstyrene (MS) and divinylbenzene (DVB), the polymer production rate after 30 minutes to 60 minutes was suppressed to 0% by weight and the initial polymerization inhibition was improved by the method of the present invention. You can see that it is doing. Further, it can be seen that the polymer generation rate after 180 minutes is also reduced, and the sustained improvement of the polymerization suppressing effect can be obtained for a long time.
[0042]
【The invention's effect】
In the production, purification, storage or transportation process of the aromatic vinyl compound, by using the polymerization suppressing method of the present invention, the polymerization of the aromatic vinyl compound or the process fluid containing the same is suppressed, and the effect is maintained for a long time. In addition, the amount of fouling (dirt) generated in the related device can be reduced. This enables long-term stable operation of related equipment and greatly contributes to safe operation.

Claims (5)

In the process of producing, purifying, storing, or transporting an aromatic vinyl compound, (A) the general formula (1) (where X is a hydrogen atom, an oxygen atom, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, And a piperidine-1-oxyl compound represented by the formula (2): wherein R 1 represents an alkoxy group having 1 to 3 carbon atoms, a carboxylic acid having 1 to 3 carbon atoms or an amide group having 1 to 3 carbon atoms. Wherein A, B, C, and D each independently represent hydrogen, a nitro group, a carboxyl group, a hydroxyl group, or a linear or branched alkyl group having 1 to 12 carbon atoms.) And (C) a general formula (3) wherein R is a hydroxyl group, an alkyl group having 1 to 32 carbon atoms, an alkylphenyl group having at least one linear or branched alkyl group having 1 to 32 carbon atoms, or Alkyl naphthyl group The polymerization inhibiting method of the aromatic vinyl compound characterized by the addition of showing.) Sulfonic acid compound represented by the.

Component (A), wherein the piperidine-1-oxyl compound is 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, The method for suppressing polymerization of an aromatic vinyl compound according to claim 1, which is at least one member selected from 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl. The 2-nitrophenol compound of the component (B) is selected from 2,4-dinitrophenol, 2,6-dinitrophenol, 2,6-dinitro-4-methylphenol, and 2,4-dinitro-6-second butylphenol. The method for suppressing polymerization of an aromatic vinyl compound according to claim 1, which is at least one selected from the group consisting of: The sulfonic acid compound of the component (C) is at least one selected from toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, and dinonylnaphthalenesulfonic acid. The method for inhibiting polymerization of an aromatic vinyl compound according to the above. The components (A) and (B) are in a weight ratio of 2:98 to 33:67, and the total amount of the components (A) and (B) and the component (C) are in a weight ratio of 99: 1 to 1: 1: The method for suppressing polymerization of an aromatic vinyl compound according to any one of claims 1 to 4, wherein the polymerization inhibitor is added at 99.