JP3550921B2 - Method for producing vinyl chloride polymer - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は塩化ビニル系重合体の製造方法に関する。詳しくは、重合器壁及び還流冷却器への付着を防止しつつ、フィッシュアイが良好な塩化ビニル系重合体を生産性良く製造する方法に関するものである。
【０００２】
【従来の技術】
塩化ビニル系重合体の製造においては、生産性の向上のため還流冷却器を付設した大型の重合器を用いる例が多くなっている。
【０００３】
【発明が解決しようとする課題】
このような重合器において、生産性を改良するために重合反応時の還流冷却器による除熱量を増加させると、反応混合物が発泡し、これに同伴された重合体が還流冷却器へ付着したり、この重合体によって還流冷却器の台管や冷却管（チューブ）が閉塞したりして除熱能力が低下し、生産性がかえって悪化する恐れがあった。また、還流冷却器及び重合器壁に飛散・付着した重合体により、得られる塩化ビニル系重合体をフィルム等の製品にした場合の未溶融粒子（以下これを「フィッシュアイ」と記す）が増加してしまう等の問題も生じていた。
【０００４】
【課題を解決するための手段】
本発者らは上記の実情に鑑み、鋭意検討を重ねた結果、塩化ビニル単量体または塩化ビニル単量体を主体とする共重合可能な単量体の混合物（以下まとめて「塩化ビニル系単量体」と記す）を水性媒体中で重合させる際に、塩化ビニル系単量体の見かけの蒸発線速を一定の値以下とすることにより、この問題点を解決できることを見いだし、本発明を完成した。
【０００５】
即ち、本発明の要旨は還流冷却器を付設した重合器を用いて、塩化ビニル系単量体を水性媒体中で重合して塩化ビニル系重合体を製造するに際して、重合反応中に還流冷却器での除熱量を測定し、この測定値に基いて還流冷却器に供給する冷却水の水量及び水温の少なくとも一方を制御することにより、重合反応中の反応混合物からの塩化ビニル系単量体の見かけの蒸発線速を５．５ｃｍ／秒以下にすることを特徴とする塩化ビニル系単量体の製造方法、に存する。
【０００７】
【発明の実施の形態】
以下、本発明について詳細に説明する。
本発明においては、還流冷却器を付設した重合器を用いて、塩化ビニル系単量体を水性媒体中で重合させる際に、重合反応中の反応混合物からの塩化ビニル系単量体の見かけの蒸発線速を５．５ｃｍ／秒以下とすることを特徴としている。
【０００８】
本発明に言う「見かけの蒸発線速」とは、単位時間当たりの反応混合物（液相部）からの塩化ビニル系単量体の蒸発量（気体換算）（即ち、気相部における単位時間当たりの塩化ビニル系単量体の体積増加）を重合器の断面積で除したもののことである。
この見かけの蒸発線速が５．５ｃｍ／秒を越えると、重合器内の気相部と液相部との界面（気液界面）から塩化ビニル系単量体が蒸発する時に、著しく発泡して、重合器の気相部内壁や還流冷却器の取付台管・冷却器チューブ等に重合体が付着しやすくなる。このため、還流冷却器の台管やチューブが閉塞したり、付着した重合体が製品の塩化ビニル系重合体中に混入したりして、生産性の低下や製品のフィッシュアイ悪化という結果となってしまう。
【０００９】
発泡防止の観点からは、見かけの蒸発線速は低い方が好ましいが、見かけの蒸発線速が１ｃｍ／秒未満のように低い場合は、還流冷却器の除熱能力を十分活用できないため、反応時間の短縮や塩化ビニル系単量体の仕込量増等の生産性向上効果が小さくなる傾向となる。
なお、重合反応中に発生する塩化ビニル系単量体の重合熱は、重合処方や運転条件により変動するので、必ずしも反応開始から終了まで一定とは限らないが、、反応期間中、即ち原料・助剤等の仕込が終了して反応混合物が所定の反応温度に到達してから、反応が所定の転化率に到達する（これは例えば、反応器の圧力の低下等で検出可能である）までの期間は、見かけの蒸発線速を５．５ｃｍ／秒以下にすることが必要である。
【００１０】
見かけの蒸発線速は、例えば以下のようにして、還流冷却器における除熱量から測定することができる。
塩化ビニル系単量体の気相部での体積をＶ、重合器の塩化ビニル系単量体の蒸発が起きる部分の断面積をＳとすると、塩化ビニル系単量体の見かけの蒸発線速ＬＶは、定義より、単位時間当たりの気相部の塩化ビニル系単量体の体積増加率を蒸発部分の断面積で除したものである。
【００１１】
【数１】
ＬＶ＝（ｄＶ／ｄｔ）／Ｓ （１）
【００１２】
重合系内の絶対温度をＴ、圧力をｐ、気相部の塩化ビニル系単量体の総モル数をｎとすれば、気体の状態方程式は次のようになる。
【００１３】
【数２】
ｐ＊Ｖ＝ｎ＊Ｒ＊Ｔ （２）
【００１４】
（２）式の両辺をｐで除した上で、時間ｔで微分する。
【００１５】
【数３】
ｄＶ／ｄｔ＝（Ｒ＊Ｔ／ｐ）＊（ｄｎ／ｄｔ） （３）
【００１６】
一方、塩化ビニル系単量体の蒸発潜熱Ｑは、塩化ビニル系単量体を塩化ビニル単量体で代表させた場合、塩化ビニル単量体の分子量をＭ、その単位重量当たりの蒸発潜熱をαで示せば、式（４）で表される。
【００１７】
【数４】
Ｑ＝ｎ＊Ｍ＊α （４）
【００１８】
この両辺を時間ｔで微分し、式（５）を得る。
【００１９】
【数５】
ｄＱ／ｄｔ＝（Ｍ＊α）＊（ｄｎ／ｄｔ） （５）
【００２０】
蒸発潜熱分を、還流冷却器で除熱・冷却していることになるので、Ｑは還流冷却器における除熱量に等しい。
還流冷却器の冷却水の入温をＴ１、出温をＴ２とし、冷却水の単位時間当たりの流量をＦ、比熱をＣで表すと、冷却による単位時間当たりの除熱量（ｄＱ／ｄｔ）は次式で示される。
【００２１】
【数６】
ｄＱ／ｄｔ＝Ｃ＊（Ｔ２−Ｔ１）＊Ｆ （６）
【００２２】
（５）、（６）式より、ｄｎ／ｄｔを与える式（７）を得る。
【００２３】
【数７】
ｄｎ／ｄｔ＝Ｃ＊（Ｔ２−Ｔ１）＊Ｆ／（Ｍ＊α） （７）
【００２４】
式（７）を式（３）に代入し、更にこれを式（１）に代入することにより、見かけの蒸発線速をＬＶを表す式（８）を得る。
【００２５】
【数８】
ＬＶ＝Ｒ＊Ｔ＊Ｃ＊（Ｔ２−Ｔ１）＊Ｆ／（ｐ＊Ｓ＊Ｍ＊α）（８）
【００２６】
なお、塩化ビニル系単量体の単位重量あたりの蒸発潜熱αは、その重合時の一般的な圧力である「７〜２０ｋｇ／ｃｍ２」においては、一般高圧ガス保安規則関係 第１２条、定置式製造設備の基準、昭５０通告２９１の第７条の２関係器通第５項の別表、に記載の値である「５８ｃａｌ／ｇ」を使用すれば良い。
【００２７】
上記の式（８）から、見かけの蒸発線速ＬＶは反応器の運転パラメータと定数とから算出することができ、また例えば還流冷却器の冷却水の入温（Ｔ１）やその流量Ｆを調節することによりＬＶを制御できることが読み取ることができる。なお上記以外にも、重合中の気液界面からの塩化ビニル系単量体の見かけの蒸発線速ＬＶの制御は、例えば還流冷却器の有効伝熱面積を、重合器中の不活性ガス量を用いて制御することによる方法等によっても可能である。
【００２８】
除熱量は、例えばプロセス中にカロリー計（熱量計）を設置して、還流冷却器に供給する冷却水の温度及び流量から、計測が可能であるので、塩化ビニル系単量体の見かけの蒸発線速を制御する方法としては、前述の還流冷却器に供給する冷却水の温度又は流量を変更する方法が、操作も容易で制御性も優れており、好適である。
また、この除熱量を制御する方法においては、ＤＤＣ（Ｄｉｒｅｃｔ Ｄｉｇ−ｉｔａｌ Ｃｏｎｔｒｏｌ）法等の制御方法を用いて最適制御を行うことがより望ましい。
【００２９】
本発明において使用される塩化ビニル系単量体は、塩化ビニル単量体単独及び塩化ビニル単量体を主体とする共重合可能な単量体の混合物を含む。塩化ビニル単量体と共重合可能な他の単量体としては、塩化ビニル単量体の重合において、従来一般的に用いられているものを使用することができ、特に限定されない。上記の他の単量体としては、例えば酢酸ビニルなどのビニルエステル類、セチルビニルエーテルなどのアルキルビニルエーテル類、エチレン、プロピレンなどのα−オレフィン類、アクリル酸メチル、メタクリル酸メチルなどの（メタ）アクリル酸アルキルエステル類、塩化ビニリデンなどのビニリデン化合物等が挙げられる。これらの他の単量体は塩化ビニル単量体に対し、通常２０重量％以下の割合で使用される。
【００３０】
本発明の方法は、水性媒体中での塩化ビニル系単量体の重合に適用できる。
一般に塩化ビニル系単量体の水性媒体中での重合は、部分ケン化ポリ酢酸ビニル（いわゆるポリビニルアルコール）等の分散安定剤を用い、塩化ビニル単量体に可溶の重合開始剤を使用する懸濁重合法、ラウリル硫酸ナトリウムなどの界面活性剤を乳化剤として用い、塩化ビニル単量体に可溶の重合開始剤を使用し、均質化処理を施した上で重合を行う微細懸濁重合法、界面活性剤を用いて、水溶性の重合開始剤を使用する乳化重合法等が例示できる。
【００３１】
本発明を適用する重合における、具体的な重合処方・方法としては、それぞれの重合法において通常使用されるものを用いればよく、特に限定されない。
更に、本発明においては、必要に応じて塩化ビニル系単量体の重合に使用される連鎖移動剤、酸化防止剤、架橋剤、ｐＨ調整剤、スケール付着防止剤等の各種重合助剤を適宜使用することができ、これらの各成分の仕込み量等は、一般的な条件で差し支えない。
【００３２】
本発明を実施するに際しての、重合器への塩化ビニル系単量体、水性媒体、分散剤・界面活性剤等の分散安定剤、重合開始剤及び各種重合助剤の仕込み割合、仕込み方法等も特に限定されるものではない。
本発明方法において重合を停止させる方法としては、いわゆる重合禁止剤や重合停止剤を添加したり、重合器から未反応単量体を回収する方法等が挙げられる。
【００３３】
塩化ビニル系重合体から、残留した塩化ビニル系単量体を除去する方法、生成した塩化ビニル系重合体を水性媒体から分離・乾燥するための方法等も、それぞれの重合方法において通常採用されている方法を用いればよい。
また、本発明において用いられる重合器の付帯機器である撹拌翼やバッフルなどの形状・種類も、一般的に採用されている設備・機器を使用することができる。
【００３４】
【実施例】
以下に、本発明方法の具体的態様を実施例を用いてより詳細に説明するが、本発明はその要旨を越えない限り、以下の実施例によって限定されるものではない。
＜実施例１＞
還流冷却器を付設した、内容積５５ｍ３、直胴部の断面積１０．５ｍ２の攪拌機及びジャケット付のステンレス製重合器に、脱イオン水１８ｍ３、ケン化度８０％の部分ケン化ポリ酢酸ビニル１３ｋｇを仕込み、脱気した。
【００３５】
次いで塩化ビニル単量体１８ｔを仕込み、重合開始剤としてジ−２−エチルヘキシルパーオキシジカーボネート（ＯＰＰ）を加えて、５７℃に昇温し、重合を開始し、同時に還流冷却器に冷却水を通じて除熱を開始した。
重合反応中、還流冷却器による塩化ビニル単量体の見かけの蒸発線速ＬＶを還流冷却器に供給する冷却水の流量を調節して除熱量を２３００Ｍｃａｌ／時にすることにより、５ｃｍ／秒に制御した。
【００３６】
反応が目標の重合転化率に達したときに、塩化ビニル単量体を系外へ回収して反応を終了させ、重合開始からここに至るまでの時間を反応時間とした。更に重合器内の塩化ビニル単量体を大気圧まで除去した後、槽内を真空吸引し冷却した。生成スラリーを重合器外へ排出した後、重合器内を乾燥し、器壁及び還流冷却器（台管部分及び冷却チューブ）への付着の生成状態を目視にて観察した。評価は下記の基準で行った。反応条件及び結果はまとめて表に示す。
【００３７】
【表１】
○：全く付着なし
△：部分的に薄い付着がある
×：広い範囲に付着
【００３８】
＜実施例２＞
重合開始剤の使用量を減らし、還流冷却器に供給する冷却水の流量を調節して除熱量を４５０Ｍｃａｌ／時とすることにより、重合中の塩化ビニル単量体の見かけの蒸発線速を１ｃｍ／秒に制御したこと以外は、実施例１と同様にして重合を行い、反応終了後の付着状態を観察した。結果を表に示す。
【００３９】
＜実施例３＞
重合開始剤の使用量を減らし、還流冷却器に供給する冷却水の流量を調節して除熱量を２３０Ｍｃａｌ／時とすることにより、重合中の塩化ビニル単量体の見かけの蒸発線速を０．５ｃｍ／秒に制御したこと以外は実施例１と同様にして重合を行い、反応終了後の付着状態を観察した。
結果は表に示す。
【００４０】
＜実施例４＞
重合開始剤としてｔ−ブチルパーオキシピバレート（ＢＰＶ）を使用し、重合温度を６５℃とし、重合反応中の還流冷却器による除熱量を２８００Ｍｃａｌ／時としたこと以外は実施例１と同様にして重合反応を行い、反応終了後の付着状態を観察した。
結果を表に示す。
【００４１】
＜実施例５＞
重合開始剤の使用量を減らし、還流冷却器に供給する冷却水の流量を調節して還流冷却器の除熱量を５６０Ｍｃａｌ／時とすることにより、重合中の塩化ビニル単量体の見かけの蒸発線速を１ｃｍ／秒に制御したこと以外は、実施例４と同様にして重合を行い、反応終了後の付着状態を観察した。結果を表に示す。
【００４２】
＜実施例６＞
重合開始剤の使用量を減らし、還流冷却器に供給する冷却水の流量を調節して還流冷却器の除熱量を２８０Ｍｃａｌ／時とすることにより、重合中の塩化ビニル単量体の見かけの蒸発線速を０．５ｃｍ／秒に制御したこと以外は、実施例４と同様にして重合を行い、反応終了後の付着状態を観察した。結果を表に示す。
【００４３】
＜比較例１＞
重合開始剤の使用量を減らし、かつ還流冷却器に冷却水を供給せずに（還流冷却器を全く使用することなく）重合を実施したこと以外は実施例１と同様にして重合を行い、反応終了後の付着状態を観察した。結果を表に併せて示す。
【００４４】
＜比較例２＞
重合開始剤の使用量を増し、還流冷却器に供給する冷却水の流量を調節して、還流冷却器の除熱量を３６００Ｍｃａｌ／時とすることにより、塩化ビニル単量体の見かけの蒸発線速を、８ｃｍ／秒に制御したこと以外は、実施例１と同様にして重合を行い、反応終了後の付着状態を観察した。結果を表に示す。
【００４５】
＜比較例３＞
上記比較例２と同様にして、還流冷却器の除熱量を２７００Ｍｃａｌ／時とし、塩化ビニル単量体の見かけの蒸発線速を６ｃｍ／秒に制御して重合を行い、反応終了後の付着状態を観察した。結果を表に示す。
【００４６】
＜比較例４＞
重合開始剤の使用量を減らし、かつ還流冷却器に冷却水を供給せずに（還流冷却器を全く使用することなく）重合を実施したこと以外は、実施例４と同様にして重合を行い、反応終了後の付着状態を観察した。結果を表に併せて示す。
【００４７】
＜比較例５＞
重合開始剤の使用量を増し、還流冷却器に供給する冷却水の流量を調節して還流冷却器による除熱量を４５００Ｍｃａｌ／時とすることにより、塩化ビニル単量体の見かけの蒸発線速を８ｃｍ／秒に制御したこと以外は、実施例４と同様にして重合を行い、反応終了後の付着状態を観察した。
結果を表に示す。
【００４８】
＜比較例６＞
上記比較例５と同様にして、還流冷却器による除熱量を３３００Ｍｃａｌ／時として、塩化ビニル単量体の見かけの蒸発線速を６ｃｍ／秒に制御して重合を行い、反応終了後の付着状態を観察した。結果を表に示す。
【００４９】
【発明の効果】
本発明方法を用いることにより、重合器の内壁及び還流冷却器への付着を少なくすることができるので、効率よく、かつ安定して塩化ビニル系重合体の製造を行うことができる。また、付着量が少なくなるので生成重合体中のフィッシュアイの改良も期待できる。
【００５０】
【表２】
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a vinyl chloride polymer. More specifically, the present invention relates to a method for producing a vinyl chloride polymer having good fish eyes with good productivity while preventing adhesion to a polymerization vessel wall and a reflux condenser.
[0002]
[Prior art]
In the production of vinyl chloride-based polymers, there are many cases where a large-sized polymerization vessel provided with a reflux condenser is used to improve productivity.
[0003]
[Problems to be solved by the invention]
In such a polymerization vessel, if the amount of heat removed by the reflux condenser during the polymerization reaction is increased in order to improve productivity, the reaction mixture foams, and the entrained polymer adheres to the reflux condenser. However, there is a possibility that the heat removal capability is reduced due to the blockage of the base tube or cooling tube (tube) of the reflux condenser by the polymer, and the productivity is rather deteriorated. In addition, unmelted particles (hereinafter referred to as “fish eyes”) when the obtained vinyl chloride polymer is converted into a film or the like increases due to the polymer scattered and adhered to the reflux condenser and the polymerization vessel wall. There have also been problems such as doing so.
[0004]
[Means for Solving the Problems]
In view of the above circumstances, the present inventors have conducted intensive studies and have found that a vinyl chloride monomer or a mixture of copolymerizable monomers mainly composed of a vinyl chloride monomer (hereinafter collectively referred to as “vinyl chloride-based It has been found that this problem can be solved by making the apparent linear velocity of the vinyl chloride monomer equal to or less than a certain value when polymerizing the monomer) in an aqueous medium. Was completed.
[0005]
That is, the gist of the present invention is to use a polymerization vessel equipped with a reflux condenser to produce a vinyl chloride polymer by polymerizing a vinyl chloride monomer in an aqueous medium . By controlling at least one of the amount and temperature of the cooling water supplied to the reflux condenser based on the measured value, the amount of the vinyl chloride monomer from the reaction mixture during the polymerization reaction is measured. A method for producing a vinyl chloride-based monomer, wherein the apparent evaporation linear velocity is 5.5 cm / sec or less .
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
In the present invention, when a vinyl chloride-based monomer is polymerized in an aqueous medium using a polymerization vessel provided with a reflux condenser, the apparent appearance of the vinyl chloride-based monomer from the reaction mixture during the polymerization reaction is reduced. It is characterized in that the evaporation linear velocity is set to 5.5 cm / sec or less.
[0008]
The term “apparent evaporation linear velocity” as used in the present invention refers to the amount of vaporized vinyl chloride monomer from the reaction mixture (liquid phase) per unit time (in terms of gas) (ie, per unit time in the gas phase). Of the vinyl chloride monomer) by the cross-sectional area of the polymerization vessel.
If the apparent linear velocity exceeds 5.5 cm / sec, the vinyl chloride monomer foams significantly when the vinyl chloride monomer evaporates from the interface (gas-liquid interface) between the gas phase and the liquid phase in the polymerization vessel. As a result, the polymer easily adheres to the inner wall of the gas phase portion of the polymerization vessel, the mounting tube and the condenser tube of the reflux condenser, and the like. For this reason, the base tube and tube of the reflux condenser are blocked, and the adhered polymer is mixed into the vinyl chloride polymer of the product, resulting in a decrease in productivity and deterioration of the fisheye of the product. Would.
[0009]
From the viewpoint of preventing foaming, the apparent evaporation linear velocity is preferably low. However, if the apparent evaporation linear velocity is as low as less than 1 cm / sec, the heat removal ability of the reflux condenser cannot be fully utilized, and the The effect of improving productivity such as shortening the time and increasing the amount of vinyl chloride monomer charged tends to decrease.
The heat of polymerization of the vinyl chloride monomer generated during the polymerization reaction varies depending on the polymerization recipe and operating conditions, and is not necessarily constant from the start to the end of the reaction. From the end of the charging of the auxiliaries and the like, when the reaction mixture reaches a predetermined reaction temperature, until the reaction reaches a predetermined conversion (this can be detected, for example, by a decrease in the pressure of the reactor). It is necessary to make the apparent evaporation linear velocity 5.5 cm / sec or less during the period.
[0010]
The apparent evaporation linear velocity can be measured from the heat removal amount in the reflux condenser as described below, for example.
Assuming that the volume of the vinyl chloride-based monomer in the gas phase is V and the cross-sectional area of the portion of the polymerization vessel where the vinyl chloride-based monomer evaporates is S, the apparent linear velocity of evaporation of the vinyl chloride-based monomer LV is, by definition, a value obtained by dividing the volume increase rate of the vinyl chloride-based monomer in the gas phase per unit time by the cross-sectional area of the evaporated portion.
[0011]
(Equation 1)
LV = (dV / dt) / S (1)
[0012]
If the absolute temperature in the polymerization system is T, the pressure is p, and the total number of moles of the vinyl chloride monomer in the gas phase is n, the equation of state of the gas is as follows.
[0013]
(Equation 2)
p * V = n * R * T (2)
[0014]
After dividing both sides of the equation (2) by p, differentiation is performed at time t.
[0015]
(Equation 3)
dV / dt = (R * T / p) * (dn / dt) (3)
[0016]
On the other hand, when the vinyl chloride monomer is represented by a vinyl chloride monomer, the vapor latent heat Q of the vinyl chloride monomer is represented by M, the molecular weight of the vinyl chloride monomer, and the latent heat of vaporization per unit weight. If represented by α, it is represented by equation (4).
[0017]
(Equation 4)
Q = n * M * α (4)
[0018]
The two sides are differentiated with respect to time t to obtain equation (5).
[0019]
(Equation 5)
dQ / dt = (M * α) * (dn / dt) (5)
[0020]
Since the latent heat of evaporation is removed and cooled by the reflux condenser, Q is equal to the amount of heat removed in the reflux condenser.
If the input temperature of the cooling water of the reflux condenser is T 1 , the output temperature is T 2 , the flow rate of the cooling water per unit time is F, and the specific heat is C, the heat removal amount per unit time by cooling (dQ / dt) ) Is shown by the following equation.
[0021]
(Equation 6)
dQ / dt = C * (T 2 −T 1 ) * F (6)
[0022]
From equations (5) and (6), equation (7) giving dn / dt is obtained.
[0023]
(Equation 7)
dn / dt = C * (T 2 −T 1 ) * F / (M * α) (7)
[0024]
By substituting equation (7) into equation (3), and further substituting this into equation (1), equation (8) representing the apparent evaporation linear velocity LV is obtained.
[0025]
(Equation 8)
LV = R * T * C * (T 2 -T 1) * F / (p * S * M * α) (8)
[0026]
The latent heat of vaporization α per unit weight of the vinyl chloride-based monomer is determined by the general pressure at the time of polymerization of “7 to 20 kg / cm 2 ”. The value of "58 cal / g" which is described in the standard of the formula manufacturing equipment, the separate table of the 5th section of the Japanese Utility Model Notification No. 291 of the article 7 of the 2nd related article, may be used.
[0027]
From the above equation (8), the apparent evaporation linear velocity LV can be calculated from the operating parameters and constants of the reactor, and for example, the cooling water input temperature (T 1 ) of the reflux condenser and the flow rate F thereof can be calculated. It can be seen that the LV can be controlled by adjusting. In addition to the above, the control of the apparent linear velocity LV of the vinyl chloride monomer from the gas-liquid interface during the polymerization can be performed by, for example, determining the effective heat transfer area of the reflux condenser and the amount of the inert gas in the polymerization reactor. It is also possible by a method or the like by performing control using.
[0028]
The amount of heat removed can be measured, for example, by installing a calorie meter (calorimeter) during the process and measuring the temperature and flow rate of the cooling water supplied to the reflux condenser, so that the apparent evaporation of the vinyl chloride monomer can be measured. As a method of controlling the linear velocity, the above-described method of changing the temperature or the flow rate of the cooling water supplied to the reflux cooler is preferable because of easy operation and excellent controllability.
Further, in the method of controlling the heat removal amount, it is more preferable to perform the optimal control using a control method such as a DDC (Direct Digital-Ital Control) method.
[0029]
The vinyl chloride monomer used in the present invention includes a vinyl chloride monomer alone and a mixture of a copolymerizable monomer mainly composed of the vinyl chloride monomer. As the other monomer copolymerizable with the vinyl chloride monomer, those commonly used in the polymerization of vinyl chloride monomers can be used, and are not particularly limited. Examples of the other monomers include vinyl esters such as vinyl acetate, alkyl vinyl ethers such as cetyl vinyl ether, α-olefins such as ethylene and propylene, and (meth) acrylic such as methyl acrylate and methyl methacrylate. Acid alkyl esters, vinylidene compounds such as vinylidene chloride, and the like. These other monomers are usually used in a proportion of 20% by weight or less based on the vinyl chloride monomer.
[0030]
The method of the present invention can be applied to polymerization of a vinyl chloride monomer in an aqueous medium.
Generally, polymerization of a vinyl chloride monomer in an aqueous medium uses a dispersion stabilizer such as partially saponified polyvinyl acetate (so-called polyvinyl alcohol) and uses a polymerization initiator soluble in the vinyl chloride monomer. Suspension polymerization method, a fine suspension polymerization method in which a surfactant such as sodium lauryl sulfate is used as an emulsifier, a polymerization initiator soluble in a vinyl chloride monomer is used, and polymerization is performed after homogenization treatment. And an emulsion polymerization method using a surfactant and a water-soluble polymerization initiator.
[0031]
In the polymerization to which the present invention is applied, specific polymerization recipes / methods may be those usually used in each polymerization method, and are not particularly limited.
Furthermore, in the present invention, if necessary, various polymerization aids such as a chain transfer agent, an antioxidant, a crosslinking agent, a pH adjuster, and a scale adhesion inhibitor used for the polymerization of the vinyl chloride monomer are appropriately used. The components can be used, and the amount of each of these components to be charged and the like can be determined under general conditions.
[0032]
In carrying out the present invention, the vinyl chloride monomer, an aqueous medium, a dispersion stabilizer such as a dispersant and a surfactant, a charge ratio of a polymerization initiator and various polymerization aids to a polymerization vessel, a charge method, and the like are also described. There is no particular limitation.
Examples of a method for terminating the polymerization in the method of the present invention include a method of adding a so-called polymerization inhibitor or a polymerization terminator, and a method of recovering an unreacted monomer from a polymerization vessel.
[0033]
A method for removing residual vinyl chloride-based monomers from a vinyl chloride-based polymer, a method for separating and drying a generated vinyl chloride-based polymer from an aqueous medium, and the like are also usually employed in each polymerization method. Method may be used.
In addition, as for the shape and type of stirring blades and baffles, which are auxiliary devices of the polymerization vessel used in the present invention, generally used equipment and devices can be used.
[0034]
【Example】
Hereinafter, specific embodiments of the method of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.
<Example 1>
A stirrer with an internal volume of 55 m 3 , a cross-sectional area of a straight body of 10.5 m 2 , and a jacketed stainless steel polymerization reactor equipped with a reflux condenser were charged with 18 m 3 of deionized water and a partially saponified poly of 80% saponification degree. 13 kg of vinyl acetate was charged and degassed.
[0035]
Next, 18t of a vinyl chloride monomer was charged, di-2-ethylhexyl peroxydicarbonate (OPP) was added as a polymerization initiator, and the temperature was raised to 57 ° C to start polymerization, and at the same time, cooling water was passed through a reflux condenser. Heat removal was started.
During the polymerization reaction, the apparent evaporation linear velocity LV of the vinyl chloride monomer by the reflux condenser is controlled to 5 cm / sec by adjusting the flow rate of the cooling water supplied to the reflux condenser to make the heat removal amount 2300 Mcal / hour. did.
[0036]
When the reaction reached the target polymerization conversion, the vinyl chloride monomer was recovered out of the system to terminate the reaction, and the time from the start of polymerization to the point at which the polymerization was reached was defined as the reaction time. After the vinyl chloride monomer in the polymerization vessel was further removed to atmospheric pressure, the inside of the tank was evacuated and cooled. After the produced slurry was discharged out of the polymerization vessel, the inside of the polymerization vessel was dried, and the generation state of the adhesion to the vessel wall and the reflux condenser (the base tube portion and the cooling tube) was visually observed. The evaluation was performed according to the following criteria. The reaction conditions and results are summarized in the table.
[0037]
[Table 1]
：: No adhesion △: Partially thin adhesion X: Adhesion over a wide area
<Example 2>
By reducing the amount of the polymerization initiator used and adjusting the flow rate of the cooling water supplied to the reflux condenser so that the heat removal amount is 450 Mcal / hour, the apparent linear velocity of the vinyl chloride monomer during the polymerization is 1 cm. The polymerization was carried out in the same manner as in Example 1 except that the rate was controlled at / sec, and the state of adhesion after the completion of the reaction was observed. The results are shown in the table.
[0039]
<Example 3>
By reducing the amount of the polymerization initiator used and adjusting the flow rate of the cooling water supplied to the reflux condenser to make the heat removal amount 230 Mcal / hour, the apparent linear velocity of the vinyl chloride monomer during the polymerization is reduced to 0. Polymerization was carried out in the same manner as in Example 1 except that the control was performed at 0.5 cm / sec, and the adhered state after the completion of the reaction was observed.
The results are shown in the table.
[0040]
<Example 4>
Same as Example 1 except that t-butyl peroxypivalate (BPV) was used as a polymerization initiator, the polymerization temperature was 65 ° C., and the heat removal by a reflux condenser during the polymerization reaction was 2800 Mcal / hour. A polymerization reaction was carried out to observe a state of adhesion after the completion of the reaction.
The results are shown in the table.
[0041]
<Example 5>
By reducing the amount of the polymerization initiator used and adjusting the flow rate of the cooling water supplied to the reflux condenser so that the heat removal amount of the reflux condenser is 560 Mcal / hour, the apparent evaporation of the vinyl chloride monomer during the polymerization is performed. Polymerization was carried out in the same manner as in Example 4 except that the linear velocity was controlled at 1 cm / sec, and the state of adhesion after the completion of the reaction was observed. The results are shown in the table.
[0042]
<Example 6>
By reducing the amount of the polymerization initiator used and adjusting the flow rate of the cooling water supplied to the reflux condenser to make the heat removal amount of the reflux condenser equal to 280 Mcal / hour, the apparent evaporation of the vinyl chloride monomer during the polymerization is performed. Polymerization was carried out in the same manner as in Example 4 except that the linear velocity was controlled to 0.5 cm / sec, and the state of adhesion after the completion of the reaction was observed. The results are shown in the table.
[0043]
<Comparative Example 1>
The polymerization was carried out in the same manner as in Example 1 except that the amount of the polymerization initiator was reduced and the polymerization was carried out without supplying cooling water to the reflux condenser (without using the reflux condenser at all). The state of adhesion after completion of the reaction was observed. The results are shown in the table.
[0044]
<Comparative Example 2>
By increasing the amount of the polymerization initiator used, adjusting the flow rate of the cooling water supplied to the reflux condenser, and setting the heat removal amount of the reflux condenser to 3600 Mcal / hr, the apparent linear velocity of the vinyl chloride monomer was reduced. Was controlled to 8 cm / sec except that the polymerization was carried out in the same manner as in Example 1, and the adhered state after the completion of the reaction was observed. The results are shown in the table.
[0045]
<Comparative Example 3>
Polymerization was performed in the same manner as in Comparative Example 2 except that the heat removal amount of the reflux condenser was set to 2700 Mcal / hour, the apparent linear velocity of the vinyl chloride monomer was controlled to 6 cm / sec, and the adhesion state after the reaction was completed. Was observed. The results are shown in the table.
[0046]
<Comparative Example 4>
The polymerization was carried out in the same manner as in Example 4, except that the amount of the polymerization initiator used was reduced and the polymerization was carried out without supplying cooling water to the reflux condenser (without using the reflux condenser at all). The state of adhesion after the reaction was completed was observed. The results are shown in the table.
[0047]
<Comparative Example 5>
By increasing the amount of the polymerization initiator used and adjusting the flow rate of the cooling water supplied to the reflux condenser so that the amount of heat removed by the reflux condenser is 4500 Mcal / hour, the apparent linear velocity of the vinyl chloride monomer can be reduced. Polymerization was carried out in the same manner as in Example 4 except that the control was performed at 8 cm / sec, and the adhered state after the completion of the reaction was observed.
The results are shown in the table.
[0048]
<Comparative Example 6>
In the same manner as in Comparative Example 5, the amount of heat removed by the reflux condenser was set to 3300 Mcal / hour, the apparent linear velocity of evaporation of the vinyl chloride monomer was controlled to 6 cm / sec, and polymerization was carried out. Was observed. The results are shown in the table.
[0049]
【The invention's effect】
By using the method of the present invention, adhesion to the inner wall of the polymerization vessel and the reflux condenser can be reduced, so that a vinyl chloride polymer can be efficiently and stably produced. Further, since the amount of adhesion is reduced, improvement of fish eyes in the produced polymer can be expected.
[0050]
[Table 2]
Claims (4)
ＬＶ＝Ｒ×Ｔ×Ｃ×（Ｔ 2 −Ｔ 1 ）×Ｆ／（ｐ×Ｓ×Ｍ×α）
但し、ＬＶ：塩化ビニル系単量体の見かけの蒸発線速
Ｒ：気体常数
Ｔ：反温混合物の絶対温度
Ｃ：冷却水の比熱
Ｔ 1 ：冷却水の入温
Ｔ 2 ：冷却水の出温
Ｆ：冷却水の供給量
ｐ：重合器の圧力
Ｓ：重合器の気液界面の面積
Ｍ：塩化ビニル単量体の分子量
α：塩化ビニル単量体の蒸発潜熱 Controlling at least one of the amount and temperature of the cooling water supplied to the reflux condenser so that the apparent evaporation linear velocity of the vinyl chloride monomer calculated by the following equation becomes a predetermined value. A method for producing the vinyl chloride polymer according to any one of claims 1 to 3 .
LV = R × T × C × (T 2 −T 1 ) × F / (p × S × M × α)
Where, LV: apparent linear velocity of evaporation of vinyl chloride monomer
R: gas constant
T: Absolute temperature of anti-warming mixture
C: Specific heat of cooling water
T 1 : Cooling water input
T 2 : Temperature of cooling water
F: Supply amount of cooling water
p: pressure of polymerization reactor
S: Area of gas-liquid interface of polymerization vessel
M: molecular weight of vinyl chloride monomer
α: latent heat of vaporization of vinyl chloride monomer
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33214996A JP3550921B2 (en) | 1996-12-12 | 1996-12-12 | Method for producing vinyl chloride polymer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33214996A JP3550921B2 (en) | 1996-12-12 | 1996-12-12 | Method for producing vinyl chloride polymer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10168103A JPH10168103A (en) | 1998-06-23 |
| JP3550921B2 true JP3550921B2 (en) | 2004-08-04 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33214996A Expired - Fee Related JP3550921B2 (en) | 1996-12-12 | 1996-12-12 | Method for producing vinyl chloride polymer |
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| Country | Link |
|---|---|
| JP (1) | JP3550921B2 (en) |
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| Publication number | Publication date |
|---|---|
| JPH10168103A (en) | 1998-06-23 |
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