JP3650520B2

JP3650520B2 - Polymerization method of vinyl chloride monomer

Info

Publication number: JP3650520B2
Application number: JP01895998A
Authority: JP
Inventors: 博光立花
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 1998-01-30
Filing date: 1998-01-30
Publication date: 2005-05-18
Anticipated expiration: 2018-01-30
Also published as: JPH11209411A

Description

【０００１】
【発明の属する技術分野】
本発明は塩化ビニル系単量体の改良された重合方法、詳しくは、生産性が高く、良好な品質を得ることができる塩化ビニル系単量体の重合法に関するものである。
【０００２】
【従来の技術】
従来、一般的に、塩化ビニル系単量体の重合法は、重合器に水、分散剤、重合開始剤、その他添加剤を仕込んで重合器内を脱気した後に該単量体を仕込み、次いで重合器ジャケットに温水を循環させて重合器内容物を重合温度まで昇温させ、重合を行う方法であった。
【０００３】
然るに、生産性を向上させる為に、重合器を大型化し、仕込み時間を短縮し、且つ重合時間を短縮した重合法が採用されてきた。つまり、重合器の大型化と重合時間の短縮面から重合反応熱の除熱の為にリフラックスコンデンサー（以下、ＲＣと記す）を稼働させ、また、仕込み時間短縮の為に脱気した重合器にまず塩化ビニル系単量体、重合開始剤等を仕込み、その後予め脱気した温水、分散剤等を仕込むの方法が採用されてきたが、生産性において未だ不十分な点があった。更に、ＲＣの稼働が重合転化率５％以前では、重合液が発泡したり、粗粒子が生成し品質が悪化したりするという問題があった。
【０００４】
【本発明が解決しようとする課題】
このような現状に鑑み、本発明の目的は、仕込時間、昇温時間、重合時間を短縮し、且つ重合初期からＲＣを稼働させ、良好な品質の重合体を生産性よく得る事ができる塩化ビニル系単量体の重合法を提供することをその目的とするものである。
【０００５】
【課題を解決するための手段】
本発明者は、生産性と品質のバランスを向上するべく種々検討した結果、特定の仕込み方法を採用すると共に、特定の水溶性高分子分散剤を使用することにより、品質上の問題を発生させることなく、生産性を大幅に向上させることが可能であることを見いだし本発明を完成した。
【０００６】
即ち、本発明は、重合反応器気相部または重合反応器外にリフラックスコンデンサーを付設した重合反応器を用いて、塩化ビニル系単量体を懸濁重合するに際して（ａ）脱気した重合器に、撹拌条件下において、予熱脱気水と塩化ビニル系単量体とを併行して仕込み、（ｂ）その仕込み期間中に、重合開始剤を塩化ビニル系単量体ラインに、少なくとも平均分子量１０万から４８０万のポリエチレンオキシドを含む分散剤の水溶液を予熱脱気水ラインに、それぞれ導入して仕込み（ｃ）仕込み終了後の重合器内温が所定重合温度±５℃の範囲になるようにし、（ｄ）次いでリフラックスコンデンサ一を稼働させて重合を行うことを特徴する塩化ビニル系単量体の重合法（請求項１）
ポリエチレンオキシドの添加量が、塩化ビニル系単量体１００重量部に対して０．００１〜０．１重量部の範囲であることを特徴とする請求項1記載の重合法（請求項２）
ポリエチレンオキシドと併用する分散剤がメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルメチルセルロース、部分鹸化ポリ酢酸ビニル、ポリビニルピロリドン、無水マレイン酸/ビニルエーテル共重合体、エチレンプロピレンオキシドブロックコポリマーから選ばれることを特徴とする請求項１〜２記載の重合法（請求項３）
撹拌開始時期が予熱脱気水及び塩化ビニル系単量体の仕込み前からこれらの総仕込量の１０％が仕込まれるまでの間にあることを特徴とする請求項１〜３記載の重合法（請求項４）
仕込み終了後の重合器内温が所定重合温度±３℃の範囲であることを特徴とする請求項１〜４記載の重合法（請求項５）
をその内容とするものである。
【０００７】
以下に本発明を詳細に説明する。
本発明の実施にあたり、まず（ａ）として脱気した重合器に、撹拌条件下において、脱気されて重合温度より高温に加熱された温水（予熱脱気水）と、塩化ビニル系単量体とを併行して仕込む。無撹拌下では予熱脱気水と塩化ビニル系単量体の混合が悪いため、異常重合反応となったり、製品の品質が悪化したりするからである。即ち、撹拌の開始は予熱脱気水と塩化ビニル系単量体を重合器に併行して仕込む前とこれら総仕込み量の１０％位が仕込まれる間に行うのがよい。
【０００８】
予熱脱気水と塩化ビニル系単量体とは併行して仕込むが、その際同時に仕込み始めても良いが、予熱脱気水を若干早く仕込み始めるのが好ましい。この時間差が長くなると仕込所要時間が長くなるので好ましくない。好ましくは１〜２分程度がよい。予熱脱気水を先に仕込み始めることにより重合が安定化され、粗粒・微粉が少なく粒度分布がシャープな重合体が得られる。予熱脱気水、塩化ビニル系単量体の仕込所要時間は
仕込ポンプ能力にもよるが各々３０分程度以内に終了する事が好ましい。
【０００９】
本発明で使用する高温の予熱脱気水とは、脱酸素処理をした工業用温水、好ましくはイオン交換水の温水であり、これは公知の方法で製造される。予熱脱気水の温度はその仕込量と塩化ビニル系単量体の温度、仕込量及び重合温度との関係において決めればよい。予熱脱気水温度はタンク、熱交換機等で所定温度にコントロールする。
【００１０】
本発明で使用する塩化ビニル系単量体の温度は通常の大気温度下の温度でよいが、タンク、熱交換機等で加温して使用しても支障がないが５０℃以下が良い。５０℃以上になると重合し仕込配管内部に重合体が生成し閉塞したりするからである。次に（ｂ）として、塩化ビニル系単量体及び予熱脱気水の仕込中に、重合開始剤を塩化ビニル系単量体ラインに、分散剤水溶液を予熱脱気水ラインに、それぞれ導入して仕込む。その際、分散剤として少なくとも平均分子量が１０万から４８０万のポリエチレンオキシドを含むことが本発明の必須要件の一つである。
【００１１】
そのポリエチレンオキシドの添加量としては塩化ビニル系単量体に１００重量部に対して０．００１〜０．１重量部、好ましくは０．００３〜０．０５重量部である。これは、０．００１重量部以下だと、ＲＣを重合初期から稼働させた場合の発泡抑制効果が少なく、粗粒子が生成したりし品質が悪くなるからである。また、０．１重量部以上では実質的にその効果は飽和するからである。
【００１２】
また、ポリエチレンオキシドの平均分子量は１０万から４８０万、好ましくは１７０万〜４８０万である。１０万未満では粒子の粗大化を防ぐ効果は見られず、４８０万を越えると粒子の安定化効果はあるものの製品のフイッシュアイが増加するためである。
本発明で、ポリエチレンオキシドと併用する分散剤は、塩化ビニル系単量体の重合に使用する分散剤であればよい。例えば、メチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース等の水溶性セルロース、部分鹸化ポリ酢酸ビニル、ポリビニルピロリドン、無水マレイン酸／ビニルエーテル共重合体、エチレンオキシドプロピレンオキシドブロックポリマー等公知の分散剤がある。使用量は塩化ビニル系単量体１００重量部に対して０．０３〜１．０重量部である。
【００１３】
本発明で使用する重合開始剤は塩化ビニル系単量体の重合に使用される公知の開始剤であればよい。例えば、ジイソプロピルパーオキシジカーボネート、ジー２−エチルヘキシルパーオキシジカーボネート、ｔ−ブチルパーオキシネオデカネート、３，５，５−トリメチルヘキサノイルパーオキサイド等の過酸化物、アゾビスー２，４−ジメチルバレロニトリル、アゾビス（４−メトキシー２，４−ジメチル）バレロニトリル等のアゾ化合物があり、これらは、単独または２種以上組み合わせて使用できる。使用量は塩化ビニル系単量体１００重量部に対して０．０３〜１．０重量部である。
【００１４】
次に（ｃ）として塩化ビニル系単量体及び予熱脱気水の仕込終了後の重合器内温が所定重合温度±５゜Ｃ、好ましく所定重合温度±３゜Ｃの範囲になるようにする。所定重合温度より高くなることは重合発熱量即ち安全面より好ましくなく、逆に所定重合温度より低くなると、更に所定の重合温度まで昇温するのに時間を要し、生産性が低下する。従ってできるだけ重合温度近くになることが好ましい。そのためには（ａ）で
述べたように重合温度、塩化ビニル系単量体の仕込量、温度及び予熱脱
気水の仕込量より予熱脱気水の温度を設定すると共に、重合器ジャケット温度も予め所定の重合温度に加温しておくのが好ましい。
【００１５】
次に（ｄ）として重合器内温度が所定の重合温度に到達すると共にＲＣを稼働させて重合を行うが、重合の途中から稼働させても何ら支障はない。本発明では、重合発熱量の全てをＲＣで除熱してもよく、ＲＣと重合器ジャケットの両方で除熱してもよい。ＲＣにおける除熱制御はバルブ開度調整による水量調節、水温調節など公知の方法によることができる。また重合器ジャケットによる除熱制御も同様の公知の方法によることができる。
【００１６】
本発明では重合器に仕込む水／塩化ビニル系単量体の仕込比率は特に限定はないが、０．６／１〜２／１の範囲、好ましくは０．８／１〜１．４／１の範囲である。
本発明での塩化ビニル系単量体とは、塩化ビニル単量体またはこれと共重合し得る他の単量体の混合物をいう。ここで、塩化ビニルと共重合し得る他の単量体としては、エチレン、プロピレン、ブテン、酢酸ビニル、塩化アリル等があり、これらは単独または２種以上併用できる。
【００１７】
本発明では、塩化ビニル系単量体の重合に適宜使用される公知の連鎖移動剤、ＰＨ調整剤、抗酸化剤、各種添加剤が必要に応じて使用できる。
これらは予熱脱気水や塩化ビニル系単量体の仕込む直前または仕込み中に仕込んでよいが、仕込み時間の短縮面から、仕込み中に仕込むのが好ましい。その仕込み配管は予熱脱気水や塩化ビニル系単量体の仕込み配管を使用して仕込んでももよいし、別の配管を使用して仕込んでもよい。
【００１８】
また、重合温度は特に限定されないが、通常は４０℃から７０℃の範囲が適当である。
【００１９】
【実施例】
以下に本発明の実施例、比較例を説明するが、これらは何ら本発明を限定するものではない。
「フイッシュアイの測定法」
フイッシュアイは下記の方法で測定した。
重合体１００重量部に対して可塑剤(DOP)５０重量部、ジブチルスズマレエート２．０重量部、エチレングリコールモノステアレート０．５重量部、酸化チタン０．５重量部、及びカーボンブラック０．１重量部を加えてブレンドし、これを１４５℃の８インチロールで５分間混練りした後、厚み０．３ｍｍのシートを取り出す。このシート１００ｃｍ2当たりの透明粒子を数えてフイッシュアイの個数とする。
「実施例１−４」「比較例１−２」
ＲＣを装備した内容量１．５ｍ3の重合器のジャケットを５５℃にし、重合器内部とＲＣ内部と共に脱気した後、撹拌条件下において、６５℃の予熱脱気水６００Ｋｇと３０℃の塩化ビニル５００Ｋｇを併行して仕込んだ。この時平均分子量３５０万のポリエチレンオキシド所定量と部分鹸化ポリ酢酸ビニル３００ｇを溶解した水溶液２０Ｌを予熱脱気水の仕込み配管から、また、ジー２―エチルヘキシルパーオキシジカーボネート１５０ｇとｔ―ブチルパーオキシネオデカネート１５０ｇを溶解したミネラルスピリット溶液８００ｃｃを塩化ビニルの仕込み配管から、予熱脱気水及び塩化ビニル仕込み中に各々仕込んだ。予熱脱気水、塩化ビニルの各々単独の仕込み時間は１０分で、併行して仕込んだので全仕込時間は１０分であった。また、仕込み終了後の内容物の温度は５５℃で、昇温の必要はなかった。即ち、仕込み時間と昇温時間の総計は１０分であった。
【００２０】
次いでＲＣを稼働させ３．５時間重合を行った。重合転化率は８２％だった。重合中、ＲＣの冷却水温度及び重合器ジャケット温度を制御し、重合反応熱をＲＣと重合器ジャケットで除熱した。ＲＣ除熱量と重合器ジャケット除熱量の比率は７０／３０とした。この時のポリエチレンオキシド量と得られた重合体の品質を表１に示す。また、撹拌開始時期を変えた場合の結果も併せて示した。
【００２１】
【表１】

【００２２】
表１から、ポリエチレンオキシドの量が少ないと重合体の平均粒子径が粗くなる傾向があり、多いとフイッシュアイが悪くなる傾向がある事が判る。また、撹拌の開始時期は、予熱脱気水及び塩化ビニルの総仕込量が１０％以下に開始するのがよい事が判る。また、本発明のポリエチレンオキシドを使用しなければ良好な重合体が得られない事も判る。
「比較例３」
重合器ジャケット温度を３０℃にし、３０℃の脱気水６００Ｋｇを使用する以外は実施例２と同じ方法で実施した。仕込み時間は１０分であった。重合器内容物の温度は３０℃であった。重合器ジャケットに温水を循環し重合温度５５℃まで昇温した。それに要した時間は５０分であった。即ち、実施例２に比較して昇温時間で５０分長く要した。重合体の平均粒子径は１１７μでフイッシュアイは１０個であった。本比較例は実施例２より、昇温時間が長く、従って生産性が悪い事がわかる。
「実施例５−８」「比較例４−５」
実施例１−４と同じ重合器で、重合器ジャケットを６５℃にし、重合器とＲＣ内部と共に脱気した後、撹拌条件下において、７５℃の予熱脱気水６００Ｋｇと３５℃の塩化ビニル５００Ｋｇを併行して仕込んだ。この時ポリエチレンオキシド所定量と部分鹸化ポリ酢酸ビニル３００ｇを溶解した水溶液２０Ｌを予熱脱気水の仕込み配管から、また、３，５，５−トリメチルヘキサノイルパーオキサイド２５０ｇとｔ―ブチルパーオキシネオデカネート１７０ｇを溶解したミネラルスピリット溶液８００ｃｃを塩化ビニルの仕込み配管から、予熱脱気水及び塩化ビニル仕込み中に各々仕込んだ。予熱脱気水、塩化ビニルの各々単独の仕込み時間は１０分で、併行して仕込んだので全仕込時間は１０分であった。また、この時、連鎖移動剤として２−メルカプトエタノール１０ｇを予熱脱気水配管から予熱脱気水仕込み中に仕込んだ。仕込み終了後の内容物の温度は６５℃で、昇温の必要はなかった。即ち、仕込み時間と昇温時間の総計は１０分であった。次いでＲＣを稼働させ３時間重合を行った。重合転化率は７５％だった。重合中、ＲＣの冷却水温度及び重合器ジャケット温度を制御し、重合反応熱をＲＣと重合器ジャケットで除熱した。ＲＣ除熱量と重合器ジャケット除熱量の比率は６５／３５とした。この時のポリエチレンオキシドの平均分子量と使用量、並びに得られた重合体の品質を表２に示す。また、撹拌開始時期を変えた場合の結果も併載した。
【００２３】
【表２】

【００２４】
表２から、ポリエチレンオキシドの平均分子量が小さいと重合体の平均粒子径が粗くなる傾向があり、大きいとフイッシュアイが悪くなる傾向がある事が判る。また、本発明のポリエチレンオキシドを使用しなければ良好な重合体が得られず、予熱脱気水及び塩化ビニル単量体の仕込終了後に撹拌を開始した場合は正常な重合ができない事が判る。
「比較例６」
３５℃の脱気水６００Ｋｇを使用する以外は実施例７と同じ方法で実施した。仕込み時間は１０分であった。重合器内容物の温度は３５℃であった。重合器ジャケットに温水を循環し重合温度６５℃まで昇温した。それに要した時間は５５分であった。即ち、実施例７に比較して昇温時間で５０分長く要した。重合体の平均粒子径は１１７μでフイッシュアイは１０個であった。本比較例は実施例７より、昇温時間が長く、生産性が悪い。
【００２５】
【発明の効果】
以上のように、本発明に従えば、仕込み時間、昇温時間を短縮でき、且つ重合初期からＲＣを稼働できるため重合反応熱の除去が容易となり、極めて生産性のよい重合法でその工業的価値は高い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improved polymerization method of a vinyl chloride monomer, and more particularly, to a polymerization method of a vinyl chloride monomer which is highly productive and can obtain good quality.
[0002]
[Prior art]
Conventionally, in general, a polymerization method of a vinyl chloride monomer is such that water, a dispersing agent, a polymerization initiator, and other additives are charged into a polymerization vessel and the monomer is charged after degassing the inside of the polymerization vessel. Subsequently, warm water was circulated through the polymerization vessel jacket to raise the polymerization vessel contents to the polymerization temperature, thereby carrying out the polymerization.
[0003]
However, in order to improve productivity, a polymerization method in which the polymerization vessel is enlarged, the charging time is shortened, and the polymerization time is shortened has been adopted. In other words, a reflux condenser (hereinafter referred to as RC) is operated to remove the heat of polymerization reaction from the viewpoint of increasing the size of the polymerization vessel and shortening the polymerization time. First, a method of first charging a vinyl chloride monomer, a polymerization initiator, and the like and then charging warm water, a dispersing agent, etc. previously deaerated has been adopted, but there are still unsatisfactory points in productivity. Furthermore, when the operation of RC is a polymerization conversion rate of 5% or less, there is a problem that the polymerization solution is foamed or coarse particles are generated to deteriorate the quality.
[0004]
[Problems to be solved by the present invention]
In view of such a current situation, the object of the present invention is to reduce the charging time, the temperature raising time, the polymerization time, and operate RC from the initial stage of polymerization to obtain a good quality polymer with good productivity. It is an object of the present invention to provide a method for polymerizing vinyl monomers.
[0005]
[Means for Solving the Problems]
As a result of various studies to improve the balance between productivity and quality, the present inventor adopts a specific preparation method and uses a specific water-soluble polymer dispersant to cause a quality problem. The present invention has been completed by finding that productivity can be significantly improved without any problems.
[0006]
That is, the present invention relates to (a) degassed polymerization in suspension polymerization of a vinyl chloride monomer using a polymerization reactor equipped with a reflux condenser outside the gas phase part of the polymerization reactor or outside the polymerization reactor. Under stirring conditions, preheated degassed water and vinyl chloride monomer are charged together, and (b) during the charging period, the polymerization initiator is at least averaged in the vinyl chloride monomer line. (C) The temperature inside the polymerization vessel after the completion of the charging is within a predetermined polymerization temperature ± 5 ° C. by introducing an aqueous solution of a dispersant containing polyethylene oxide having a molecular weight of 100,000 to 4.8 million into the preheated degassing water line. And (d) a method of polymerizing a vinyl chloride monomer, wherein the polymerization is carried out by operating a reflux capacitor (Claim 1).
2. The polymerization method according to claim 1, wherein the amount of polyethylene oxide added is in the range of 0.001 to 0.1 parts by weight with respect to 100 parts by weight of the vinyl chloride monomer.
The dispersant used in combination with polyethylene oxide is selected from methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, partially saponified polyvinyl acetate, polyvinyl pyrrolidone, maleic anhydride / vinyl ether copolymer, and ethylene propylene oxide block copolymer. The polymerization method according to 1-2 (Claim 3)
The polymerization method according to claim 1, wherein the stirring start time is from before the preheated degassed water and the vinyl chloride monomer are charged until 10% of the total charged amount is charged. (Claim 4)
5. The polymerization method according to claim 1, wherein the temperature inside the polymerization vessel after completion of the charging is in a range of a predetermined polymerization temperature ± 3 ° C. (Claim 5)
Is the content.
[0007]
The present invention is described in detail below.
In carrying out the present invention, first, (a) a degassed polymerizer is heated under a stirring condition and degassed and heated to a temperature higher than the polymerization temperature (preheated degassed water), and a vinyl chloride monomer. And charge in parallel. This is because the mixture of preheated degassed water and vinyl chloride monomer is poor under no stirring, resulting in an abnormal polymerization reaction or a deterioration in product quality. That is, the stirring is preferably started before the preheated degassed water and the vinyl chloride monomer are charged together in the polymerizer and while about 10% of the total charged amount is charged.
[0008]
The preheated degassed water and the vinyl chloride monomer are charged in parallel. At that time, the preheated degassed water may be started at the same time, but it is preferable to start the preheated degassed water slightly earlier. If this time difference is long, the required charging time becomes long, which is not preferable. Preferably about 1-2 minutes is good. By starting the preheated degassed water first, the polymerization is stabilized, and a polymer with few coarse particles and fine particles and a sharp particle size distribution is obtained. The time required for charging the preheated degassed water and the vinyl chloride monomer is preferably within 30 minutes, depending on the charging pump capacity.
[0009]
The high-temperature preheated degassed water used in the present invention is industrial warm water subjected to deoxidation treatment, preferably hot water of ion exchange water, which is produced by a known method. The temperature of the preheated degassed water may be determined in relation to the charged amount, the temperature of the vinyl chloride monomer, the charged amount, and the polymerization temperature. The preheated degassed water temperature is controlled to a predetermined temperature using a tank, heat exchanger or the like.
[0010]
The temperature of the vinyl chloride monomer used in the present invention may be a normal atmospheric temperature, but there is no problem even if it is heated in a tank, a heat exchanger or the like, but it is preferably 50 ° C. or lower. This is because when the temperature is 50 ° C. or higher, polymerization occurs and a polymer is formed inside the feeding pipe and is blocked. Next, as (b), during the preparation of the vinyl chloride monomer and the preheated degassed water, the polymerization initiator was introduced into the vinyl chloride monomer line, and the dispersant aqueous solution was introduced into the preheated degassed water line. Prepare. In this case, it is one of the essential requirements of the present invention that the dispersant contains at least an average molecular weight of polyethylene oxide of 100,000 to 4.8 million.
[0011]
The amount of polyethylene oxide added is 0.001 to 0.1 parts by weight, preferably 0.003 to 0.05 parts by weight, based on 100 parts by weight of the vinyl chloride monomer. This is because, when the amount is 0.001 part by weight or less, the effect of suppressing foaming is small when RC is operated from the initial stage of polymerization, and coarse particles are produced, resulting in poor quality. Further, when the amount is 0.1 parts by weight or more, the effect is substantially saturated.
[0012]
The average molecular weight of polyethylene oxide is 100,000 to 4.8 million, preferably 1.7 million to 4.8 million. If it is less than 100,000, the effect of preventing the coarsening of the particles is not observed, and if it exceeds 4.8 million, although there is an effect of stabilizing the particles, the fish eye of the product increases.
In the present invention, the dispersant used in combination with polyethylene oxide may be any dispersant that is used for polymerization of a vinyl chloride monomer. For example, there are known dispersants such as water-soluble cellulose such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, partially saponified polyvinyl acetate, polyvinyl pyrrolidone, maleic anhydride / vinyl ether copolymer, ethylene oxide propylene oxide block polymer. The amount used is 0.03 to 1.0 part by weight with respect to 100 parts by weight of the vinyl chloride monomer.
[0013]
The polymerization initiator used in the present invention may be a known initiator used for polymerization of vinyl chloride monomers. For example, peroxides such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butylperoxyneodecanate, 3,5,5-trimethylhexanoyl peroxide, azobis-2,4-dimethylvalero There are azo compounds such as nitrile and azobis (4-methoxy-2,4-dimethyl) valeronitrile, and these can be used alone or in combination of two or more. The amount used is 0.03 to 1.0 part by weight with respect to 100 parts by weight of the vinyl chloride monomer.
[0014]
Next, as (c), the internal temperature of the polymerization vessel after completion of the addition of the vinyl chloride monomer and the preheated degassed water is set within a predetermined polymerization temperature ± 5 ° C, preferably within a predetermined polymerization temperature ± 3 ° C. . A temperature higher than the predetermined polymerization temperature is not preferable from the viewpoint of the amount of heat generated by polymerization, that is, safety, and conversely, if the temperature is lower than the predetermined polymerization temperature, it takes time to further raise the temperature to the predetermined polymerization temperature, resulting in a decrease in productivity. Therefore, it is preferable to be as close to the polymerization temperature as possible. For that purpose, as described in (a), the temperature of the preheated degassed water is set from the polymerization temperature, the charged amount of the vinyl chloride monomer, the temperature and the charged amount of preheated degassed water, and the temperature of the polymer jacket is also set. It is preferable to preheat to a predetermined polymerization temperature.
[0015]
Next, as (d), the temperature in the polymerization vessel reaches a predetermined polymerization temperature and the RC is operated to perform the polymerization. However, there is no problem even if the polymerization is started in the middle of the polymerization. In the present invention, the entire amount of heat generated by polymerization may be removed by RC, or heat may be removed by both RC and the polymerization vessel jacket. The heat removal control in RC can be performed by a known method such as water volume adjustment or water temperature adjustment by adjusting the valve opening. The heat removal control by the polymerizer jacket can also be performed by the same known method.
[0016]
In the present invention, the charging ratio of the water / vinyl chloride monomer charged into the polymerization vessel is not particularly limited, but is in the range of 0.6 / 1 to 2/1, preferably 0.8 / 1 to 1.4 / 1. Range.
The vinyl chloride monomer in the present invention refers to a vinyl chloride monomer or a mixture of other monomers copolymerizable therewith. Here, other monomers that can be copolymerized with vinyl chloride include ethylene, propylene, butene, vinyl acetate, allyl chloride, and the like, and these can be used alone or in combination of two or more.
[0017]
In the present invention, known chain transfer agents, pH adjusters, antioxidants, and various additives that are appropriately used for polymerization of vinyl chloride monomers can be used as necessary.
These may be charged immediately before or during the charging of preheated degassed water or vinyl chloride monomer, but are preferably charged during the charging from the viewpoint of shortening the charging time. The charging pipe may be charged using preheated degassed water or a vinyl chloride monomer charging pipe, or may be charged using another pipe.
[0018]
The polymerization temperature is not particularly limited, but usually a range of 40 ° C to 70 ° C is appropriate.
[0019]
【Example】
Examples of the present invention and comparative examples will be described below, but these do not limit the present invention.
"Method for measuring fish eye"
The fish eye was measured by the following method.
50 parts by weight of plasticizer (DOP), 2.0 parts by weight of dibutyltin maleate, 0.5 parts by weight of ethylene glycol monostearate, 0.5 parts by weight of titanium oxide, and carbon black One part by weight is added and blended, and this is kneaded for 5 minutes with an 8-inch roll at 145 ° C., and then a sheet having a thickness of 0.3 mm is taken out. The transparent particles per 100 cm @ 2 of this sheet are counted as the number of fish eyes.
"Example 1-4""Comparative example 1-2"
The jacket of the 1.5m3 polymer vessel equipped with RC is set to 55 ° C, and after degassing the inside of the polymerizer and the inside of RC, 600Kg of preheated degassed water at 65 ° C and vinyl chloride at 30 ° C under stirring conditions. 500 kg was charged in parallel. At this time, 20 L of an aqueous solution in which a predetermined amount of polyethylene oxide having an average molecular weight of 3.5 million and 300 g of partially saponified polyvinyl acetate was dissolved was added from a preheated degassing water charging pipe, 150 g of di-2-ethylhexyl peroxydicarbonate and t-butyl peroxy 800 cc of a mineral spirit solution in which 150 g of neodecanate was dissolved was charged into preheated degassed water and vinyl chloride from a vinyl chloride charging pipe. The pre-heating degassed water and vinyl chloride were each charged for 10 minutes, and were charged in parallel, so the total charging time was 10 minutes. Further, the temperature of the contents after the completion of the charging was 55 ° C., and it was not necessary to raise the temperature. That is, the total of the charging time and the heating time was 10 minutes.
[0020]
Subsequently, RC was operated and polymerization was performed for 3.5 hours. The polymerization conversion rate was 82%. During the polymerization, the RC cooling water temperature and the polymerizer jacket temperature were controlled, and the heat of polymerization reaction was removed by the RC and the polymerizer jacket. The ratio of RC heat removal amount and polymerizer jacket heat removal amount was 70/30. Table 1 shows the amount of polyethylene oxide and the quality of the obtained polymer. Moreover, the result at the time of changing stirring start time was also shown collectively.
[0021]
[Table 1]

[0022]
From Table 1, it can be seen that when the amount of polyethylene oxide is small, the average particle size of the polymer tends to be coarse, and when it is large, the fish eye tends to be poor. Moreover, it turns out that it is good for the start time of stirring to start the total preparation amount of preheating deaeration water and vinyl chloride to 10% or less. It can also be seen that a good polymer cannot be obtained unless the polyethylene oxide of the present invention is used.
“Comparative Example 3”
The same procedure as in Example 2 was performed, except that the temperature of the polymerization reactor jacket was 30 ° C. and 600 kg of degassed water at 30 ° C. was used. The charging time was 10 minutes. The temperature of the contents of the polymerization vessel was 30 ° C. Warm water was circulated through the polymerization vessel jacket to raise the polymerization temperature to 55 ° C. It took 50 minutes. That is, it took 50 minutes longer in temperature raising time than in Example 2. The average particle size of the polymer was 117 μm and the number of fish eyes was 10. It can be seen that the temperature of the comparative example is longer than that of Example 2 and therefore the productivity is poor.
"Example 5-8""Comparative Example 4-5"
In the same polymerization apparatus as in Example 1-4, the polymerization apparatus jacket was set to 65 ° C., and after degassing together with the polymerization apparatus and the inside of the RC, under stirring conditions, 600 kg of preheated degassed water at 75 ° C. and 500 kg of vinyl chloride at 35 ° C. Was prepared in parallel. At this time, 20 L of an aqueous solution in which a predetermined amount of polyethylene oxide and 300 g of partially saponified polyvinyl acetate were dissolved was supplied from a preheated deaerated water charging pipe, 250 g of 3,5,5-trimethylhexanoyl peroxide and t-butylperoxyneodeca 800 cc of a mineral spirit solution in which 170 g of the acid had been dissolved was charged into the preheated degassed water and the vinyl chloride from the vinyl chloride charging pipe. The pre-heating degassed water and vinyl chloride were each charged for 10 minutes, and were charged in parallel, so the total charging time was 10 minutes. At this time, 10 g of 2-mercaptoethanol as a chain transfer agent was charged into the preheated degassed water from the preheated degassed water pipe. The temperature of the contents after the completion of the charging was 65 ° C., and it was not necessary to raise the temperature. That is, the total of the charging time and the heating time was 10 minutes. Next, RC was operated and polymerization was carried out for 3 hours. The polymerization conversion rate was 75%. During the polymerization, the RC cooling water temperature and the polymerizer jacket temperature were controlled, and the heat of polymerization reaction was removed by the RC and the polymerizer jacket. The ratio of the RC heat removal amount and the polymerization jacket jacket heat removal amount was 65/35. Table 2 shows the average molecular weight and the amount of polyethylene oxide used, and the quality of the obtained polymer. The results when the stirring start time was changed are also shown.
[0023]
[Table 2]

[0024]
From Table 2, it can be seen that when the average molecular weight of polyethylene oxide is small, the average particle diameter of the polymer tends to be coarse, and when it is large, the fish eye tends to be poor. Further, it can be seen that a good polymer cannot be obtained unless the polyethylene oxide of the present invention is used, and normal polymerization cannot be carried out when stirring is started after completion of the preheated degassed water and the vinyl chloride monomer.
“Comparative Example 6”
The same procedure as in Example 7 was performed except that 600 kg of degassed water at 35 ° C. was used. The charging time was 10 minutes. The temperature of the contents of the polymerization vessel was 35 ° C. Warm water was circulated through the polymerization vessel jacket to raise the polymerization temperature to 65 ° C. It took 55 minutes. That is, it took 50 minutes longer in temperature raising time than in Example 7. The polymer had an average particle size of 117 μm and 10 fish eyes. This comparative example has a longer heating time and lower productivity than Example 7.
[0025]
【The invention's effect】
As described above, according to the present invention, the charging time and the temperature raising time can be shortened, and RC can be operated from the initial stage of polymerization, so that it is easy to remove the heat of polymerization reaction, and the industrial method is a highly productive polymerization method. Value is high.

Claims

Using a polymerization reactor equipped with a reflux condenser outside the polymerization reactor gas phase part or outside the polymerization reactor, a mixture of vinyl chloride monomer or other monomer copolymerizable with this (hereinafter both (A) Warm water (hereinafter referred to as preheated degassed water) that has been degassed and heated to a temperature higher than the polymerization temperature in a deaerated polymerizer under stirring conditions. And (b) a vinyl chloride monomer in parallel, and (b) during the charging period, a polymerization initiator is added to the vinyl chloride monomer line at least at an average molecular weight of 100,000 to 4.8 million. An aqueous solution of a dispersant containing ethylene oxide is introduced into each preheated degassing water line and charged, and (c) the temperature inside the polymerization vessel after completion of the charging is within a predetermined polymerization temperature ± 5 ° C., (d) Reflux condenser Polymerization of vinyl chloride monomer, wherein the polymerization is carried out is operated.

The polymerization method according to claim 1, wherein the addition amount of polyethylene oxide is in the range of 0.001 to 0.1 parts by weight with respect to 100 parts by weight of the vinyl chloride monomer.

The dispersant used in combination with polyethylene oxide is selected from methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, partially saponified polyvinyl acetate, polyvinyl pyrrolidone, maleic anhydride / vinyl ether copolymer, and ethylene propylene oxide block copolymer. The polymerization method in any one of 1-2.

According to claim 1, stirring start time is equal to or in between the front feed preheat degassed water and vinyl chloride monomer to 10% of the total charged amount of these are charged Polymerization method.

The polymerization method according to any one of claims 1 to 4 , wherein the internal temperature of the polymerization vessel after completion of charging is in a range of a predetermined polymerization temperature ± 3 ° C.