JP4776874B2 - Process for producing olefin polymer - Google Patents

Description

【００３７】
流動層反応器内の直胴部の平均ガス流速を上記のような条件とする方法については後述する。
また流動層において、重合はオレフィンの種類および共重合割合、飽和脂肪族炭化水素の量、ガス流速などによっても異なるが、通常、重合圧力は１〜１００ｋｇ／ｃｍ²、好ましくは２〜４０ｋｇ／ｃｍ²の範囲内で、重合温度Ｔ_Rは、反応器の排出ガス温度（≒Ｔ_out）とほぼ同温であり、通常２０〜１３０℃、好ましくは５０〜１２０℃、より好ましくは７０〜１１０℃の範囲内で行われる。
【００３８】
上記共重合は必要に応じて水素などの分子量調節剤の存在下に行うこともでき、任意の場所から供給することができる。
上記のように生成したオレフィン系重合体は、反応器下部から連続的または断続的に抜き出された後、通常乾燥される。上記のような飽和脂肪族炭化水素は非重合性であって重合によって消耗することはなく、反応系でガス化した飽和脂肪族炭化水素は未反応重合モノマーとともにラインから排出され、通常冷却された後反応器に循環されるが、非蒸発分は通常生成オレフィン系重合体に含まれて反応器から抜き出されるので、その減量分を任意の場所から補給することができる。
【００３９】
上記のような反応器からラインを介して排出されるガスは、通常熱交換器において冷却して、該ガス中に含まれる飽和脂肪族炭化水素の一部を液化して気液混合状態とした後、反応器に循環させる。
このように排出ガスを反応器に循環させる際には、排出ガスの一部をパージしてもよい。この反応器から排出されるガスは、飽和脂肪族炭化水素に加えて、通常、未反応重合モノマー、水素ガス、不活性ガスなどを含有している。
【００４０】
本発明では、このように排出ガスを反応器に循環させる際には、熱交換器で冷却され、気液混合状態とされた飽和脂肪族炭化水素をそのまま供給口から反応器に流動化ガスとして循環することが好ましい。
また、排出ガスを例えば気液分離機能を備えた熱交換器で冷却した後、気液混合状態とされた飽和脂肪族炭化水素を気液分離して、分離されたガス相を例えば供給口から流動層反応器に循環させ、液相の一部あるいは全部を供給ラインに供給して、他の補給用炭化水素類とともに流動層反応器に循環させてもよい。
【００４１】
本発明では、得られるオレフィン系重合体の分子量は、重合温度などの重合条件を変更することにより調節することもできるし、水素（分子量調節剤）の使用量を制御することにより調節することもできる。
流動層反応器内を上述したＣ₁＞Ｃ₂、Ｖ₁＞Ｖ₂を満たすような条件とする方法としては、
（１）ガス導入域に供給されるガスの流れの全部又は一部の方向を変更する手段を有する流動層反応器を用い、かつガス導入域に供給されるガスに、飽和脂肪族炭化水素が気−液混合状態で含まれるようにする方法、
（２）ガス導入域に供給されるガスに上記直胴部の円周方向の運動量を与える手段を有し、かつ、ガス導入域に供給されるガスに、飽和脂肪族炭化水素が気−液混合状態で含まれるようにする方法、
（３）ガス分散板の中心から０．７〜１．０の位置であるガス分散板周縁部に設けた供給口から液相状態の飽和脂肪族炭化水素を供給する方法、などがある。
【００４２】
まず、（１）の方法について説明する、
（１）の方法を実施するための手段としては、例えば反応器内部であって、ガス分散板下方のガス導入域に、ガス分散板へのガスの流れを分配するとともにガス分散板の下方部分にてガスの流れを乱流にするための散気板を設ける方法がある。このような散気板を設けた気相流動層反応器の一態様を図３、図４に示す。なお、図３および図４は、（１）の方法を図１に示した流動層反応器に適用した場合を示しているが、図２に示したような多段気相重合装置であっても同様に構成できる。
【００４３】
図３および図４は、散気板を備えた気相流動層反応装置の一例を部分的に示すものである。流動層反応器１１の散気板４２は、流動層反応器１１の最下部からある程度離されて配置された水平板である。この散気板４２は、供給管９の先端部であって、流動層重合器１１の内部にまで臨んでいる部分で支えられている。
散気板４２の中央部には中央穴４２ａが形成されており、散気板４２の下面には、前記中央穴４２ａを取り囲むように、供給管９の先端が当接している。また、供給管９の先端部のうち、流動層重合器１１内に臨む部分には、複数の縦割りスリット９ａ、９ａ、……が、供給管９の周方向に適当な間隔（例えば等間隔）で設けられている。
【００４４】
このため、供給管９から流動層重合器１１に送られて来たガスは、図３および図４に示すように、散気板４２の中央穴４２ａおよびスリット９ａを通過して、それぞれ矢印４５で示す中央上方流れおよび矢印４７で示す周囲環状流れとなって、流動層反応器１１のガス分散板１７よりも下のガス導入域１１ｂ内で還流する。
【００４５】
詳しくは、中央上方流れ４５は、散気板４２の中央穴４２ａからその上方に向かった後、噴水のように放射状に周辺へ落下するごとき流れとなり、周囲環状流れ４７は、供給管９の穴９ｂ（流動層反応器１１の導入口ともいえる。）を起点として、そこからスリット９ａ、９ａ、……を介して放射状に流動層反応器１１の半球状底部１１ａの内壁面に沿って円弧を描くごとき流れとなる。
【００４６】
その結果、両流れは混ざり合い、これによってガス導入域１１ｂの内壁面に粉状ポリマーが沈降して滞留したり、付着したりせずに、ガス分散板１７の微細穴１７ａから再び流動層反応器１１の流動層１８に至るようになる。
本発明では、上記散気板は、流動層反応器の軸線に対し全体的に垂直に置かれることが好ましい。
【００４７】
また、上記散気板は、図３に示したようにガス分散板に対しほぼ平行に設けてもよく、またガス分散板に対し凹状となるように設けたり、ガス分散板に対し凸状となるように設けたりすることもできる。
本発明では、ガス導入域の高さ（導入管９の開口部からガス分散板下面までの高さ）が直径に対し１．５以下、好ましくは０．７〜１．０の範囲にあることが好ましい。
【００４８】
また、上記散気板は、中央穴の面積（Ａ₂）と、散気板下面の面積（Ａ₁）との比が以下の関係を満たすことが望ましい。
０．１＜Ａ₂／Ａ₁＜０．７５
および
０．５＜（ｄ_o−ｄ_e）／２ｈ＜５
（式中、ｄ_oは散気板の直径であり、ｄ_eは導入管の直径（内径）であり、ｈは、散気板の下部外縁からガス導入域壁までの最小距離である。）
このときには、散気板の全流れ面積に基づく速度ヘッド（Ｈｖ）が下記式を満たすことが好ましい。
【００４９】
Ｈｖ＞０．３４ｋＰａ
以上説明した散気板は、中央に穴を設けたものであるが、本発明で用いられる散気板は、上面が傾斜形状であってもよい。このような、上面が傾斜形状の散気板を設けた気相流動層反応器の他の態様を図５に示す。なお、図５は、（１）の方法を図１に示した流動層反応器に適用した場合を示しているが、図２に示したような多段気相重合装置であっても同様に構成できる。
【００５０】
流動層反応器１１の散気板５２は、ガス分散板１７よりも下方に位置する。散気板５２は、流動層反応器１１の導入口９ｂに気相循環系の一部である導入管９から送られて来る気相のガス分散板１７への流れを流動層反応器１１の半球状底部１１ａの内壁面に沿って分配するための装置であって、中空で閉じられた錐体形状をしている。
【００５１】
この実施の形態では、散気板５２は、上部円錐形部５１と、この上部円錐形部５１の底面に相当する部分が、下方に突出するごとき形状をした下部偏平状円錐形部５３とからなるとともに、次のディメンションで設定された円錐体（錐体）である。
（ｉ）上部錐形部５１の垂直断面の形状は二等辺三角形であって、その頂角θ１の角度は９０゜である。下部偏平状錐形部１３の垂直断面の形状も同じく二等辺三角形であって、その頂角θ２の角度は１５０゜である。ただし、これらの角度に限定されることはなく、θ１は、８０°〜１２０°の範囲で、θ２は、１２０°〜１６０°の範囲で設定されればよい。
（ii）前記散気板の最大径寸法Ｄ２（図５参照）は１.３・Ｄ１である。
【００５２】
ただし、Ｄ１は、前記気相循環系を構成する管の内径を示し、Ｄ２は、上記の値に限定されず、１.１・Ｄ１〜１.５・Ｄ１の範囲であればよい。
（iii）前記散気板と前記流動層反応器底部との距離Ｈ１は、次の式で求められ、係数ｋを１.０として求めた場合の値である。
Ｈ１＝ｋ・（Ｄ１2・π／４）／（Ｄ２・π）
ただし、係数ｋは０．８以上１．２以下にする。
【００５３】
なお、図５において、符号５４が示すものは、散気板５２の上面（上部円錐形部５１の実質上の円錐面のこと）を意味する。この上面５４に、流動層反応器１１の導入口９ｂから導入され、周囲環状流れ４７によって舞上げられる粉状ポリマーが沈降するようになる。また、上面５４は、バグ仕上げ（鏡面仕上げ）が施されていると、上面５４に積もった粉状ポリマーはより滑り易くなり好ましい。
【００５４】
また、上面５４には均厚な図示しない複数または少なくとも双数の穴があけられている。そして、散気板５２には、モノマー、例えばエチレンでパージラインを配し（図示しない）、すなわち微圧を立てることによって、前記複数の穴から散気板５２内に粉状ポリマーが入らないようにしている。
このような上面が傾斜形状の散気板５２は、前記した形状のものに限られず、その垂直断面で見た場合における側辺（上面の傾斜部）が凹弧状曲線となるようにしたものでもよい。この場合の散気板の全体形状は、例えば管楽器のベル（通称「朝顔」）部分に相当するラッパ形状といえる。
【００５５】
また、上面が傾斜形状の散気板は、その垂直断面で見た場合における側辺が凸弧状曲線となるようにしたものでもよい。この場合の散気板の全体形状は、ドーム形状といえる。
さらに、上面が傾斜形状の散気板は、その垂直断面で見た場合における側辺を直線となるようにしたものでもよい。この場合の散気板の全体形状は、円錐形状といえる。
【００５６】
この他に、傾斜体は、その全体形状が円錐形に近い多角錐形であってもよい。
次に、（２）の方法について説明する。
（２）の方法では、ガス分散板の下部に、流動層に供給される流体に直胴部の円周方向の運動量を与える手段を有する流動層反応器を用い、かつ、流動層反応器内に飽和脂肪族炭化水素を気−液混合状態で導入する。
【００５７】
上記円周方向の運動量を与える手段としては、ガス導入域に気−液混合状態の飽和脂肪族炭化水素を含むガスを供給する供給管の供給口が、流動層反応器の直胴部の中心軸を外れて設けられており、かつ直胴部の中心と供給口の中心とを結ぶ線に対し１度以上の角度を有するように上記ガスを吹き込む方法がある。供給口は、流動層反応器の直胴部の内半径を１としたとき、該直胴部の中心を起点として、該中心から０．２〜１．０の位置であることが好ましく、ガスの吹き込み方向は、直胴部の中心と供給口の中心とを結ぶ線に対し３０〜１５０度の範囲であることが好ましい。
【００５８】
また、円周方向の運動量を与える手段としては、ガス導入域内の供給口近傍に、導入ガスに円周方向の運動量を与えるような整流板を設ける方法もある。
次に、（３）の方法について説明する。
（３）の方法では、ガス分散板の中心から０．７〜１．０の位置であるガス分散板周縁部に設けた供給口から液相状態の飽和脂肪族炭化水素を供給する。このとき、該中心から０．７未満の位置であるガス分散板中心部に設けた供給口から気相状態の飽和脂肪族炭化水素を供給することができる。上記分散板周縁部に設けた供給口は、ガス分散板の上流側、下流側のいずれに設けたものであってもよいが、液相を適切に分散させる観点からは、ガス分散板の上流側であることが好ましい。
【００５９】
この方法では、冷却器等を用いて循環ガスに含まれる飽和脂肪族炭化水素の一部を液相で分離し、得られた液相の飽和脂肪族炭化水素をガス分散板周縁部に設けた供給口から供給するとともに、含有する飽和脂肪族炭化水素の一部を分離した循環ガスを、ガス分散板中心部に設けた供給口から供給することが通常行われる。本発明では、ガス分散板周縁部に設けた供給口から供給する液相状態の飽和脂肪族炭化水素の少なくとも一部を、流動層反応器の外部から供給することができ、ガス分散板中心部に設けた供給口から供給する気相状態の飽和脂肪族炭化水素の少なくとも一部を、流動層反応器の外部から供給することができる。
【００６０】
（触媒）
本発明では、上記のような共重合を、チーグラー型チタン触媒、フィリップ型酸化クロム触媒などのエチレン重合用触媒として公知の触媒を広く用いて行うことができるが、このような触媒のうちでも特にメタロセン系触媒を用いることが望ましい。
【００６１】
具体的に本発明において好ましく用いられるメタロセン系触媒は、例えば、
（Ａ）周期律表第IVＢ族から選ばれる遷移金属のメタロセン化合物、
および
（Ｂ）（B-1）有機アルミニウムオキシ化合物、
(B-2)有機アルミニウム化合物、および
(B-3）メタロセン化合物（Ａ）と反応してイオン対を形成する化合物
から選ばれる少なくとも１種の化合物を含んでなる。
【００６２】
（（Ａ）メタロセン化合物）
周期律表第IVＢ族から選ばれる遷移金属のメタロセン化合物（Ａ）は、具体的に、次式（ｉ）で示される。
ＭＬx …（ｉ）
（式中、ＭはＺｒ、Ｔｉ、Ｈｆ、Ｖ、Ｎｂ、ＴａおよびＣｒから選ばれる遷移金属であり、Ｌは遷移金属に配位する配位子であり、少なくとも１個のＬはシクロペンタジエニル骨格を有する配位子であり、シクロペンタジエニル骨格を有する配位子以外のＬは、水素原子、ハロゲン原子、炭素原子数１〜１２の炭化水素基、アルコキシ基、アリーロキシ基、トリアルキルシリル基またはＳＯ₃Ｒ基（ここでＲはハロゲンなどの置換基を有していてもよい炭素原子数１〜８の炭化水素基）であり、ｘは遷移金属の原子価である。）
シクロペンタジエニル骨格を有する配位子としては、例えば、シクロペンタジエニル基、メチルシクロペンタジエニル基、ジメチルシクロペンタジエニル基、トリメチルシクロペンタジエニル基、テトラメチルシクロペンタジエニル基、ペンタメチルシクロペンタジエニル基、エチルシクロペンタジエニル基、メチルエチルシクロペンタジエニル基、プロピルシクロペンタジエニル基、メチルプロピルシクロペンタジエニル基、ブチルシクロペンタジエニル基、メチルブチルシクロペンタジエニル基、ヘキシルシクロペンタジエニル基などのアルキル置換シクロペンタジエニル基あるいはインデニル基、４,５,６,７−テトラヒドロインデニル基、フルオレニル基などを例示することができる。これらの基は、ハロゲン原子、トリアルキルシリル基などで置換されていてもよい。
【００６３】
これらの中では、アルキル置換シクロペンタジエニル基が特に好ましい。
シクロペンタジエニル骨格を有する配位子以外の配位子として、具体的にハロゲンとしては、フッ素、塩素、臭素、ヨウ素などが挙げられ、炭素原子数１〜１２の炭化水素基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基などのアルキル基；シクロペンチル基、シクロヘキシル基などのシクロアルキル基；フェニル基、トリル基などのアリール基；ベンジル基、ネオフィル基などのアラルキル基などが挙げられ、アルコキシ基としては、メトキシ基、エトキシ基、ブトキシ基などが挙げられ、アリーロキシ基としては、フェノキシ基などが挙げられ、ＳＯ₃Ｒ基としては、ｐ−トルエンスルホナト基、メタンスルホナト基、トリフルオロメタンスルホナト基などが挙げられる。
【００６４】
上記一般式で表される化合物がシクロペンタジエニル骨格を有する基を２個以上含む場合には、そのうち２個のシクロペンタジエニル骨格を有する基同士は、エチレン、プロピレンなどのアルキレン基、イソプロピリデン、ジフェニルメチレンなどの置換アルキレン基、シリレン基またはジメチルシリレン基、ジフェニルシリレン基、メチルフェニルシリレン基などの置換シリレン基などを介して結合されていてもよい。
【００６５】
このようなシクロペンタジエニル骨格を有する配位子を含むメタロセン化合物は、例えば遷移金属の原子価が４である場合、より具体的には下記式（ii）で示される。
Ｒ² _kＲ³ _lＲ⁴ _mＲ⁵ _nＭ …（ii）
（式中、Ｍは上記遷移金属であり、Ｒ²はシクロペンタジエニル骨格を有する基（配位子）であり、Ｒ³、Ｒ⁴およびＲ⁵はシクロペンタジエニル骨格を有する基または上記したような他の基であり、ｋは１以上の整数であり、ｋ＋ｌ＋ｍ＋ｎ＝４である。）
本発明ではこの式 Ｒ² _kＲ³ _lＲ⁴ _mＲ⁵ _nＭ において、Ｒ²、Ｒ³、Ｒ⁴およびＲ⁵のうち少なくとも２個、例えばＲ²およびＲ³が、シクロペンタジエニル骨格を有する基（配位子）であるメタロセン化合物が好ましく用いられる。これらのシクロペンタジエニル骨格を有する基は、アルキレン基、置換アルキレン基、シリレン基または置換シリレン基などを介して結合されていてもよい。
【００６６】
上記のようなメタロセン化合物としては、具体的にＭがジルコニウムであるとき、ビス（シクロペンタジエニル）ジルコニウムジクロリド、ビス（シクロペンタジエニル）ジルコニウムジブロミド、ビス（シクロペンタジエニル）ジメチルジルコニウム、ビス（シクロペンタジエニル）ジフェニルジルコニウム、ビス（シクロペンタジエニル）ジベンジルジルコニウム、ビス（シクロペンタジエニル）ジルコニウムビス（メタンスルホナト）、ビス（シクロペンタジエニル）ジルコニウムビス（p-トルエンスルホナト）、ビス（シクロペンタジエニル）ジルコニウムビス（トリフルオロメタンスルホナト）、ビス（メチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（ジメチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（エチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（メチルエチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（プロピルシクロペンタジエニル）ジルコニウムジクロリド、ビス（メチルプロピルシクロペンタジエニル）ジルコニウムジクロリド、ビス（ブチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（メチルブチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（トリメチルシクロペンタジエニル）ジルコニウムジクロリド、ビス（インデニル）ジルコニウムジクロリド、ビス（インデニル）ジルコニウムジブロミド、ビス（４,５,６,７−テトラヒドロインデニル）ジルコニウムジクロリド、ビス（フルオレニル）ジルコニウムジクロリド、エチレンビス（インデニル）ジルコニウムジクロリド、エチレンビス（インデニル）ジルコニウムジブロミド、エチレンビス（インデニル）ジメチルジルコニウム、イソプロピリデン（シクロペンタジエニル-フルオレニル）ジルコニウムジクロリド、イソプロピリデン（シクロペンタジエニル-メチルシクロペンタジエニル）ジルコニウムジクロリド、ジメチルシリレンビス（シクロペンタジエニル）ジルコニウムジクロリド、ジメチルシリレンビス（メチルシクロペンタジエニル）ジルコニウムジクロリド、ジメチルシリレンビス（トリメチルシクロペンタジエニル）ジルコニウムジクロリド、ジメチルシリレンビス（インデニル）ジルコニウムジクロリド、ジメチルシリレンビス（２−メチルインデニル）ジルコニウムジクロリド、ジメチルシリレンビス（２−メチル−４−イソプロピルインデニル）ジルコニウムジクロリド、ジメチルシリレン（シクロペンタジエニル-フルオレニル）ジルコニウムジクロリド、ジフェニルシリレンビス（インデニル）ジルコニウムジクロリドなどが挙げられる。
【００６７】
なお上記例示において、シクロペンタジエニル環の二置換体は１,２−および１,３−置換体を含み、三置換体は１,２,３−および１,２,４−置換体を含む。またプロピル、ブチルなどのアルキル基は、ｎ−、ｉ−、sec−、tert−などの異性体を含む。
また上記のようなジルコニウムメタロセン化合物において、ジルコニウムを、チタン、ハフニウム、バナジウム、ニオブ、タンタルまたはクロムに置換えた化合物を挙げることもできる。
【００６８】
本発明では、メタロセン化合物（Ａ）として、少なくとも２個のシクロペンタジエニル骨格を含む配位子を有するジルコニウムメタロセン化合物が好ましく用いられる。これら化合物は２種以上を組み合わせて用いてもよい。
（（B-1）有機アルミニウムオキシ化合物）
（B-1）有機アルミニウムオキシ化合物は、従来公知のベンゼン可溶性のアルミノキサンであってもよく、また特開平２−２７６８０７号公報で開示されているようなベンゼン不溶性の有機アルミニウムオキシ化合物であってもよい。
【００６９】
なおこのアルミノキサンは、少量の有機金属成分を含有してもよい。また回収されたアルミノキサンの溶液から溶媒あるいは未反応有機アルミニウム化合物を蒸留して除去した後、溶媒に再溶解して用いてもよい。
アルミノキサンを製造する際に用いられる有機アルミニウム化合物としては、具体的には、有機アルミニウム化合物（B-2）として後述するようなものが挙げられ、これらを２種以上組み合わせて用いることもできる。これらのうち、トリアルキルアルミニウムおよびトリシクロアルキルアルミニウムが特に好ましい。
【００７０】
またベンゼン不溶性の有機アルミニウムオキシ化合物は、６０℃のベンゼンに溶解するＡｌ成分がＡｌ原子換算で１０％以下、好ましくは５％以下、特に好ましくは２％以下であり、ベンゼンに対して不溶性ないしは難溶性である。
このような有機アルミニウムオキシ化合物のベンゼンに対する溶解性は、１００ミリグラム原子のＡｌに相当する該有機アルミニウムオキシ化合物を１００ｍｌのベンゼンに懸濁した後、攪拌下６０℃で６時間混合した後、ジャケット付Ｇ−５ガラス製フィルターを用い、６０℃で熱時濾過を行い、フィルター上に分離された固体部を６０℃のベンゼン５０ｍｌを用いて４回洗浄した後の全濾液中に存在するＡｌ原子の存在量（ｘミリモル）を測定することにより求められる（ｘ％）。本発明では、有機アルミニウムオキシ化合物（B-1）を２種以上組合わせて用いることもできる。
【００７１】
（（B-2）有機アルミニウム化合物）
本発明で用いられる有機アルミニウム化合物（B-2）は、例えば下記一般式（iii）で示される。
Ｒ¹ _nＡｌＸ_3-n …（iii）
（式（iii）中、Ｒ¹は炭素原子数１〜１２の炭化水素基であり、Ｘはハロゲン原子または水素原子であり、ｎは１〜３である。）
上記一般式（iii）において、Ｒ¹は炭素原子数１〜１２の炭化水素基、例えばアルキル基、シクロアルキル基またはアリール基であるが、具体的には、メチル基、エチル基、n-プロピル基、イソプロピル基、イソブチル基、ペンチル基、ヘキシル基、オクチル基、シクロペンチル基、シクロヘキシル基、フェニル基、トリル基などである。
【００７２】
このような有機アルミニウム化合物（B-2）としては、具体的には、トリメチルアルミニウム、トリエチルアルミニウム、トリイソプロピルアルミニウム、トリイソブチルアルミニウムなどのトリアルキルアルミニウム；イソプレニルアルミニウムなどのアルケニルアルミニウム、ジメチルアルミニウムクロリド、ジエチルアルミニウムクロリド、ジイソプロピルアルミニウムクロリド、ジイソブチルアルミニウムクロリド、などのジアルキルアルミニウムハライド；メチルアルミニウムセスキクロリド、エチルアルミニウムセスキクロリド、イソプロピルアルミニウムセスキクロリドなどのアルキルアルミニウムセスキハライド；メチルアルミニウムジクロリド、エチルアルミニウムジクロリド、イソプロピルアルミニウムジクロリドなどのアルキルアルミニウムジハライド；ジエチルアルミニウムハイドライド、ジイソブチルアルミニウムハイドライドなどのアルキルアルミニウムハイドライドなどを挙げることができる。
【００７３】
また有機アルミニウム化合物（B-2）として、下記一般式（iv）で示される化合物を用いることもできる。
Ｒ¹ _nＡｌＹ_3-n …（iv）
（式（iv）中、Ｒ¹は上記と同様であり、Ｙは−ＯＲ²基、−ＯＳｉＲ³ ₃基、−ＯＡｌＲ⁴ ₂基、−ＮＲ⁵ ₂基、−ＳｉＲ⁶ ₃基または−Ｎ（Ｒ⁷）ＡｌＲ⁸ ₂基であり、ｎは１〜２であり、Ｒ²、Ｒ³、Ｒ⁴およびＲ⁸はメチル基、エチル基、イソプロピル基、イソブチル基、シクロヘキシル基、フェニル基などであり、Ｒ⁵は水素原子、メチル基、エチル基、イソプロピル基、フェニル基、トリメチルシリル基などであり、Ｒ⁶およびＲ⁷はメチル基、エチル基などである。）
【００７４】
これらのうちでは、トリアルキルアルミニウムが好ましく、トリイソブチルアルミニウムが特に好ましい。有機アルミニウム化合物（B-2）を２種以上組み合わせて用いることもできる。
（（B-3）前記メタロセン化合物（Ａ）と反応してイオン対を形成する化合物）
本発明で用いられる前記メタロセン化合物（Ａ）と反応してイオン対を形成する化合物（B-3）としては、特開平１−５０１９５０号公報、特開平１−５０２０３６号公報、特開平３−１７９００５号公報、特開平３−１７９００６号公報、特開平３−２０７７０３号公報、特開平３−２０７７０４号公報、ＵＳ−５３２１１０６号明細書などに記載されたルイス酸、イオン性化合物およびカルボラン化合物を挙げることができる。
【００７５】
ルイス酸としては、トリフェニルボロン、トリス（４−フルオロフェニル）ボロン、トリス（ｐ−トリル）ボロン、トリス（ｏ−トリル）ボロン、トリス（３,５−ジメチルフェニル）ボロン、トリス（ペンタフルオロフェニル）ボロン、ＭｇＣｌ₂、Ａｌ₂Ｏ₃、ＳｉＯ₂−Ａｌ₂Ｏ₃などを挙げることができる。
イオン性化合物としては、トリフェニルカルベニウムテトラキス（ペンタフルオロフェニル）ボレート、トリｎ−ブチルアンモニウムテトラキス（ペンタフルオロフェニル）ボレート、Ｎ,Ｎ−ジメチルアニリニウムテトラキス（ペンタフルオロフェニル）ボレート、フェロセニウムテトラ（ペンタフルオロフェニル）ボレートなどを挙げることができる。
【００７６】
カルボラン化合物としては、ドデカボラン、１−カルバウンデカボラン、ビスｎ−ブチルアンモニウム（１−カルベドデカ）ボレート、トリｎ−ブチルアンモニウム（７,８−ジカルバウンデカ）ボレート、トリｎ−ブチルアンモニウム（トリデカハイドライド−７−カルバウンデカ）ボレートなどを挙げることができる。
【００７７】
これらは、２種以上組み合わせて用いることもできる。本発明では、共触媒成分（Ｂ）として、上記のような成分（B-1）、（B-2）および（B-3）から選ばれる少なくとも１種の化合物が用いられ、これらを適宜組み合わせて用いることもできる。これらのうちでも共触媒成分（Ｂ）として少なくとも（B-2）または（B-3）を用いることが望ましい。
【００７８】
（固体触媒）
本発明では、上記のようなメタロセン触媒成分および共触媒成分を含む触媒を用いることが好ましいが、通常これら触媒成分を粒子状担体化合物と接触させて、担体担持型触媒（固体触媒）として用いることが好ましい。
担体化合物としては、粒径１０〜３００μｍ、好ましくは２０〜２００μｍの顆粒状ないしは微粒子状固体が用いられる。この担体の比表面積は通常５０〜１０００ｍ²／ｇであり、細孔容積は０.３〜２.５ｃｍ³／ｇであることが望ましい。
【００７９】
このような担体としては、多孔質無機酸化物が好ましく用いられ、具体的にはＳｉＯ₂、Ａｌ₂Ｏ₃、ＭｇＯ、ＺｒＯ₂、ＴｉＯ₂、Ｂ₂Ｏ₃、ＣａＯ、ＺｎＯ、ＢａＯ、ＴｈＯ₂などまたはこれらを含む混合物、例えばＳｉＯ₂−ＭｇＯ、ＳｉＯ₂−Ａｌ₂Ｏ₃、ＳｉＯ₂−ＴｉＯ₂、ＳｉＯ₂−Ｖ₂Ｏ₅、ＳｉＯ₂−Ｃｒ₂Ｏ₃、ＳｉＯ₂−ＴｉＯ₂−ＭｇＯなどが用いられる。これらの中では、ＳｉＯ₂および／またはＡｌ₂Ｏ₃を主成分とするものが好ましい。
【００８０】
上記無機酸化物には少量のＮａ₂ＣＯ₃、Ｋ₂ＣＯ₃、ＣａＣＯ₃、ＭｇＣＯ₃、Ｎａ₂ＳＯ₄、Ａｌ₂（ＳＯ₄）₃、ＢａＳＯ₄、ＫＮＯ₃、Ｍｇ（ＮＯ₃）₂、Ａｌ（ＮＯ₃）₃、Ｎａ₂Ｏ、Ｋ₂Ｏ、Ｌｉ₂Ｏなどの炭酸塩、硫酸塩、硝酸塩、酸化物成分が含有されていてもよい。
また担体として有機化合物を用いることもでき、例えばエチレン、プロピレン、１−ブテン、４−メチル−１−ペンテンなどの炭素原子数２〜１４のα−オレフィンを主成分として生成される（共）重合体あるいはビニルシクロヘキサン、スチレンを主成分として生成される重合体あるいは共重合体を用いることができる。
【００８１】
担体と上記各成分の接触は、通常−５０〜１５０℃、好ましくは−２０〜１２０℃の温度で、１分〜５０時間、好ましくは１０分〜２５時間行うことが望ましい。
上記のようにして調製される固体触媒は、担体１ｇ当たり、メタロセン化合物（Ａ）が遷移金属原子として５×１０^-6〜５×１０^-4グラム原子、好ましくは１０^-5〜２×１０^-4グラム原子の量で、成分（Ｂ）は、担体１ｇ当たりアルミニウム原子またはホウ素原子として１０^-3〜５×１０^-2グラム原子、好ましくは２×１０^-3〜２×１０^-2グラム原子の量で担持されていることが望ましい。
【００８２】
さらに本発明では、上記のような固体触媒をそのままで重合に用いることができが、この固体触媒にオレフィンを予備重合させて予備重合触媒を形成してから用いることもできる。
（重合）
本発明では、固体触媒または予備重合触媒は、遷移金属／リットル（重合容積）で、通常１０^-8〜１０^-3グラム原子／リットル、さらには１０^-7〜１０^-4グラム原子／リットルとなる量で用いられることが望ましい。
【００８３】
また予備重合触媒を用いるときには成分（Ｂ）を用いても用いなくてもよいが、重合系中の遷移金属に対する成分（Ｂ）中のアルミニウムまたはホウ素の原子比（ＡｌまたはＢ／遷移金属）で、５〜３００、好ましくは１０〜２００、さらに好ましくは１５〜１５０となる量で必要に応じて用いることができる。
本発明では、上記のような気相重合により、オレフィン系重合体を顆粒状粒子で得ることができる。この粒子の平均粒径は、２５０〜３０００μｍ程度、好ましくは４００〜１５００μｍ程度であることが望ましい。
【００８４】
本発明では、オレフィン系重合体として、特に密度（ＡＳＴＭ Ｄ１５０ Ｅ）が０．８６５〜０．９２５ｇ／ｃｍ³、好ましくは０．８８０〜０．９２０ｇ／ｃｍ³である直鎖状低密度ポリエチレンを製造することが好ましく、この直鎖状低密度ポリエチレンは、エチレンから導かれる単位８７．０〜９７．６モル％、好ましくは９０．０〜９６．８モル％の量で、炭素原子数４〜１０のオレフィンから導かれる単位を１３．０〜２．４モル％、好ましく１０．０〜３．２モル％の量で含有していることが望ましい。
【００８５】
なおオレフィン系重合体は、本発明の目的を損なわない範囲であればポリエン類などの他の共重合モノマーから導かれる単位を１０重量％以下、好ましくは５重量％以下、特に好ましくは３重量％以下の量で含んでいてもよい。
【００８６】
【発明の効果】
本発明によれば、流動層反応器を用いるオレフィンの気相重合を優れた除熱効率で行うことができ、オレフィン系重合体製造時に熱偏在によるポリマーのシーティングまたはメルティングを生じにくい。
【００８７】
【実施例】
以下、実施例に基づいて本発明をさらに具体的に説明するが、本発明はこれら実施例に限定されるものではない。
【００８８】
〔実施例１〕
（固体触媒成分の調製）
２５０℃で１０時間乾燥したシリカ（ＳｉＯ₂）１０ｋｇを、１５４リットルのトルエンに懸濁した後、０℃まで冷却した。この懸濁液に、メチルアルミノオキサンのトルエン溶液（Ａｌ＝１．５２モル／リットル）５０．５リットルを１時間かけて懸濁液の温度を０〜５℃に保持しながら滴下し、引続き０℃で３０分間保持した後、１．５時間かけて９５℃まで昇温して９５℃で４時間保持した。
【００８９】
その後６０℃まで降温し、上澄み液をデカンテーションにより除去した。このようにして得られた固体触媒成分をトルエンで２回洗浄した後、トルエン１００リットルで再懸濁して全量１６０リットルとした。
得られた懸濁液に、ビス（１,３−ｎ−ブチルメチルシクロペンタジエニル）ジルコニウムジクロリドのトルエン溶液（Ｚｒ＝２５．７ミリモル／リットル）２２．０リットルを８０℃で３０分かけて滴下し、さらに８０℃に２時間保持した。その後上澄み液を除去し、ヘキサンで２回洗浄することにより、シリカ１ｇ当たり、３．２ｍｇのジルコニウムを含有する固体触媒成分を得た。
【００９０】
（固体触媒成分の予備重合）
充分に窒素置換した３５０リットルの反応器に、上記固体触媒成分７．０ｋｇを装入し、ヘキサンを装入して全容積２８５リットルのヘキサン懸濁液とした。
系内を１０℃まで冷却した後、エチレンを流量８Ｎｍ³／ｈｒで５分間、固体触媒成分のヘキサン懸濁液中に吹き込んだ。この間、系内の温度は１０〜１５℃に保持した。
【００９１】
エチレンの供給を一旦停止した後、トリイソブチルアルミニウムを２．４モルおよび１−ヘキセン１．２ｋｇを供給し、系内を密封系にした後、エチレンの供給を再開し、流量８Ｎｍ³／ｈｒで１５分間供給した後、流量を２Ｎｍ³／ｈｒに下げて、系内の圧力を０．８ｋｇ／ｃｍ²-G にした。この間に系内温度は３５℃まで上昇した。
【００９２】
その後、系内の温度を３２〜３５℃にコントロールしながら、エチレンを４Ｎｍ³／ｈｒの流量で３．５時間供給した。この間、系内の圧力は０．７〜０．８ｋｇ／ｃｍ²-Gに保持した。次いで、系内を窒素置換し、上澄み液を除去した後、ヘキサンで２回洗浄した。予備重合後の上澄み液は無色透明であった。
上記のようにして固体触媒成分１ｇ当たり３ｇの予備重合体を含む予備重合触媒を得た。この予備重合触媒（予備重合体）の１３５℃デカリン中で測定した極限粘度［η］は２．１ｄｌ／ｇであり、１−ヘキセン単位含量は４．８重量％であった。予備重合触媒の形状は良好であり、嵩密度は０．４ｇ／ｃｍ³であった。
【００９３】
（気相重合）
図１に示すような連続式流動床反応器を用いて気相重合を行った。
すなわち、上記のようにして得られた予備重合触媒を６７．８ｇ／ｈｒの量で連続的に供給して、イソペンタンの存在下にエチレンを連続的に重合させ、ポリエチレン（ＰＥ）を得た。
【００９４】
この重合は、表１に示すように、重合温度８０℃、重合圧力１．７ＭＰａ−Ｇ（ゲージ圧）、エチレン分圧１．１ＭＰａ、空塔速度０．６０ｍ／ｓ、反応器の減速領域におけるガス（ＴＯＰガス）中のイソペンタン濃度２０モル％の条件で行った。この重合が行われている間、該ＴＯＰガスの平均分子量が３８．０ｇ／モルであり、密度が２５．９ｋｇ／ｍ³であった。また、該ＴＯＰガスの露点は７８．１℃であり、熱交換器の循環ガス出口側の温度が７５．０℃であり、該循環ガス出口側の凝縮液比率が３．３重量％であった。なお、上記ＴＯＰガスは、エチレン、窒素、水素、１−ヘキセン、イソペンタンの混合物で平均分子量は３８ｇ／モルである。
【００９５】
上記のようにして得られたポリエチレンは、表１に示すように、密度（ＡＳＴＭ Ｄ１５０５）が０．９１８ｋｇ／ｍ³であり、ＭＦＲ（ＡＳＴＭ Ｄ１２３８、１９０℃、荷重２．１６ｋｇ）が３．８ｇ／10分であった。また、単位容積当たりの重合量（ＳＴＹ；Space Time Yield）は２００ｋｇ／ｈ・ｍ³であり、触媒活性は３５００ｇ−ＰＥ／ｇ−ベア触媒であった。なお、塊状のポリエチレンは発生しなかった。
【００９６】
〔実施例２、比較例１および比較例２〕
実施例１において、エチレンの重合を表１に示す条件に変えたこと以外は、実施例１と同様にしてポリエチレン（ＰＥ）を得た。
実施例１、２および比較例１、２の条件および重合結果を表１に示す。
なお、ガス分散板上流部でのミスト濃度は、分散板下部にサンプリングノズルを設置してガスサンプルを採取し、そのガス組成より分散板下部での圧力、温度条件における飽和状態の液比率を算出してミスト濃度とした。すなわち、ミスト濃度に半径方向の分布が生じている場合には、中心部で採取したガスに比べて周縁部で採取したガスの方がイソペンタンおよび１−ヘキセン濃度が高い。
【００９７】
【表１】

【図面の簡単な説明】
【図１】本発明に係るポリオレフィンの製造方法による重合プロセスの概略説明図を示す。
【図２】本発明に係るポリオレフィンの製造方法において、他の循環プロセスの概略説明図を示す。
【図３】本発明で用いられる散気板の一例を示す垂直断面図である。
【図４】図３の要部拡大図である。
【図５】本発明で用いられる散気板の他の例を示す垂直断面図である。
【符号の説明】
１１ …流動層反応器
１１ａ…直胴部
１１ｂ…ガス導入域
１７ …ガス分散板
１８ …流動層
４２ …散気板
５２ …散気板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an olefin polymer using a fluidized bed reactor, and more particularly to a method for producing an olefin polymer that is unlikely to cause local heating in a fluidized bed.
[0002]
[Prior art]
Polyolefin is used in various applications. For example, a film formed from linear low density polyethylene (LLDPE) has excellent heat sealability, flexibility and toughness, water resistance, moisture resistance, It has excellent properties such as excellent chemical properties and low cost, and has been widely used in the past.
[0003]
Such polyolefin is generally produced by a liquid phase polymerization method such as solution polymerization or slurry polymerization. In particular, LLDPE uses ethylene and an α-olefin having 4 or more carbon atoms in the presence of a Ziegler catalyst. It is manufactured by copolymerization by a liquid phase polymerization method.
By the way, when such a polyolefin is produced by a gas phase polymerization method, the polyolefin is obtained in the form of particles after the polymerization, and there is no need for steps such as particle precipitation or particle separation from the polymerization solution, which can simplify the production process. Therefore, in recent years, the production of polyolefins by gas phase polymerization, particularly LLDPE, has been actively studied.
[0004]
In the gas phase polymerization method, by supplying a polymerization monomer gas from the lower part of the reactor, the solid particles composed of the catalyst and the generated polyolefin are fluidized to form a fluidized bed to perform a polymerization reaction, and the generated polymer is continuously produced. Polymerization is carried out while being withdrawn from the reactor periodically or intermittently.
In such a gas phase polymerization method, removal of heat of polymerization is a major issue. Conventionally, a saturated aliphatic hydrocarbon that can be liquefied is supplied to a fluidized bed reactor, and the gas discharged from the reactor is compressed and cooled. A method of removing heat of polymerization by partially liquefying saturated aliphatic hydrocarbons and circulating the saturated aliphatic hydrocarbons in a gas-liquid mixed state to a reactor is known.
[0005]
However, even if the conventional heat removal method as described above is adopted, it is difficult to remove heat uniformly in the fluidized bed, and local heating in the fluidized bed is likely to occur, causing phenomena such as sheeting or melting. There was a problem that it was easy. When a sheet-like or massive polymer is formed in this way, it accumulates on the gas dispersion plate at the bottom of the fluidized bed and cannot maintain a normal fluidized state, or clogs the holes in the gas dispersion plate. In some cases, the normal operation of the vehicle was significantly hindered.
[0006]
As a result of intensive studies under these circumstances, the present inventors have found that local heating in the fluidized bed is concentrated on the peripheral edge of the fluidized bed reactor, and that local heating is suppressed. Finds that it is effective to selectively introduce saturated aliphatic hydrocarbons in the liquid phase into the fluidized bed and eliminate the heat removal failure at the periphery of the fluidized bed reactor by heat of vaporization. The invention has been completed.
[0007]
[Problems to be solved by the invention]
An object of this invention is to provide the manufacturing method of the olefin polymer which can perform the gas phase polymerization of the olefin using a fluidized bed reactor with the outstanding heat removal efficiency with high productivity.
[0008]
[Means for Solving the Problems]
  The method for producing an olefin polymer according to the present invention uses a fluidized bed reactor having a gas dispersion plate having a large number of gas passage holes in the lower portion of the straight body portion, and is provided inside the fluidized bed reactor, The gas containing at least the polymerization monomer supplied to the lower gas introduction zone is blown into the fluidized bed through the gas dispersion plate and discharged from the upper part of the reactor to circulate in the reactor, and the solid particles are fluidized by this gas flow. In the (co) polymerization of one or more olefins in the gas phase,
  A saturated aliphatic hydrocarbon is introduced into the fluidized bed in a liquid phase and a gas phase, and
  In the immediate vicinity of the upstream portion of the gas dispersion plate, when the inner radius of the straight body portion of the fluidized bed reactor is 1, the center of the straight body portion is the starting point at a position of 0.7 to 1.0 from the center. The concentration of saturated aliphatic hydrocarbons in the liquid phase at the periphery of a trunk (C₁), And the concentration of saturated aliphatic hydrocarbons in the liquid phase at the center of the trunk that is less than 0.7 from the center (C₂) And C₁> C₂TheWhen the inner radius of the straight body portion of the fluidized bed reactor is set to 1 in the vicinity of the upstream portion of the gas dispersion plate, 0.7 to 1.0 from the center. The average gas flow velocity (V ₁ ), And the average gas flow velocity (V) of the gas flow at the center of the trunk that is less than 0.7 from the center ₂ ) And V ₁ > V ₂ MeetIt is characterized by (co) polymerization under such conditions.
[0010]
In the present invention, the fluidized bed reactor has means for changing the direction of all or part of the flow of the gas supplied to the gas introduction zone, and
The gas supplied to the gas introduction region preferably contains saturated aliphatic hydrocarbons in a gas-liquid mixed state.
In the present invention, the fluidized bed reactor has means for imparting a circumferential momentum of the straight body portion to the gas supplied to the gas introduction region, and
It is also preferable that saturated aliphatic hydrocarbons are contained in a gas-liquid mixed state in the gas supplied to the gas introduction region.
[0011]
Furthermore, in this invention, it is also preferable to supply the saturated aliphatic hydrocarbon of a liquid phase state from the supply port provided in the gas dispersion plate peripheral part which is a position of 0.7-1.0 from the center of a gas dispersion plate.
It is preferable to (co) polymerize at least one α-olefin selected from ethylene and an α-olefin having 3 to 20 carbon atoms by the method for producing an olefin polymer as described above.
DETAILED DESCRIPTION OF THE INVENTION
[0012]
Hereafter, the manufacturing method of the olefin polymer which concerns on this invention is demonstrated concretely.
In the present specification, the term “polymerization” is sometimes used in the meaning including not only homopolymerization but also copolymerization, and the term “polymer” refers not only to homopolymer but also to copolymerization. It may be used in the meaning that also includes coalescence.
[0013]
In the present invention, when an olefin polymer is produced by a gas phase polymerization reaction by supplying an olefin to a fluidized bed reactor in which polymer particles containing a catalyst are maintained in a fluidized state, a saturated aliphatic hydrocarbon is produced together with the olefin. Is supplied to the fluidized bed in a liquid phase state and a gas phase state, preferably in a gas-liquid mixed state, and the polymerization heat is removed by evaporation of the saturated aliphatic hydrocarbon in the liquid phase. At this time, (co) polymerization is performed so that the concentration of the saturated aliphatic hydrocarbon in the liquid phase satisfies a specific condition.
[0014]
The present invention will now be described in detail with reference to FIG. In the fluidized bed reactor 11, a catalyst is supplied from the line 15, and a gas containing at least a polymerization monomer (olefin) supplied from the supply line 12 is supplied from the supply pipe 9 at the bottom of the reactor to the inside of the fluidized bed reactor 11. Then, the gas is supplied to the gas introduction zone 11b below the gas dispersion plate 17, blown into the fluidized bed 18 from the gas dispersion plate 17, and circulated through the reactor by being discharged from the line 16 above the reactor. A fluidized bed (reaction system) 18 is formed by maintaining solid particles (solid catalyst and produced polymer) in a fluidized state by (fluidized gas). In the present invention, the saturated aliphatic hydrocarbon is supplied to the fluidized bed 18 in a liquid phase state and a gas phase state, or in a gas-liquid mixed state. In addition, in FIG. 1, 11a shows a straight body part.
[0015]
In such a fluidized bed 18, polymer particles produced by polymerization of at least one olefin selected from ethylene and olefins having 3 to 20 carbon atoms are continuously or intermittently discharged from the reactor via the extraction line 10. Extracted.
In addition, the unreacted gaseous olefin, saturated aliphatic hydrocarbon, and the like that have passed through the fluidized bed 18 are reduced in flow rate in the deceleration region 19 provided in the upper part of the fluidized bed reactor 11, and the fluidized bed. The gas is provided to the outside of the fluidized bed reactor 11 through a gas outlet provided at the top of the reactor 11.
[0016]
Unreacted gaseous olefin, saturated aliphatic hydrocarbon, and the like discharged from the fluidized bed reactor 11 are cooled by a heat exchanger (cooling device) 14 through a circulation line 16 and merged with a supply line 12. The blower 13 continuously feeds the fluidized bed 18 in the first fluidized bed reactor 11 again. In the heat exchanger 14, the circulating gas is usually cooled to a temperature near the dew point of the gas. The dew point is the temperature at which liquid condensate begins to form in the gas. When the circulating gas is cooled to a temperature below the dew point and supplied into the fluidized bed 18, the heat of reaction can be removed by the latent heat of vaporization of the liquid condensate, and the heat removal efficiency in the fluidized bed 18 can be improved. When circulating the circulating gas to the first fluidized bed reactor 11, a part of the circulating gas may be purged from any place in the circulation line 16.
[0017]
Further, after the exhaust gas is cooled by, for example, a heat exchanger having a gas-liquid separation function, the saturated aliphatic hydrocarbon in a gas-liquid mixed state is gas-liquid separated, and the separated gas phase is converted into, for example, the supply port 9. May be circulated to the fluidized bed reactor 11 and the liquid phase supplied directly to the lower part of the fluidized bed 18. Alternatively, part or all of the liquid phase may be supplied to the supply line 12 and circulated to the fluidized bed reactor 11 together with other supplementary hydrocarbons.
[0018]
As described above, the fluidizing gas comprising the polymerization monomer and the circulating gas is introduced into the fluidized bed reactor 11 from the supply pipe 9, and normally flows at such a flow rate that the fluidized bed 18 can be maintained in a fluidized state by the gas. However, the amount of gas introduced through the supply pipe 9 specifically determines the minimum fluidization speed of the fluidized bed U_mfWhen about 3U_mf~ 50U_mfDegree, preferably about 5U_mf~ 30U_mfIt is desirable that the flow rate be of the order. The fluidized bed 18 can also be stirred mechanically, for example, by using various types of stirrers such as a squid type stirrer, a screw type stirrer, and a ribbon stirrer. The reactor may also be equipped with a scraper.
[0019]
Olefin polymerization can be carried out in two or more stages by changing the reaction conditions. Next, the polymerization process in the case where the polymerization is performed in two or more stages will be specifically described with reference to FIG.
When the polymerization is performed in two or more stages, for example, when the polymerization is performed in a multistage gas phase polymerization apparatus having two gas phase fluidized bed reactors connected in series, the polymerization is performed as follows.
[0020]
In the multistage gas phase polymerization apparatus, for example, as shown in FIG. 2, a first fluidized bed reactor 11 and a second fluidized bed reactor 21 are connected in series. The first fluidized bed reactor 11 is substantially the same as the fluidized bed reactor shown in FIG.
The polymer particles produced in the first fluidized bed reactor 11 are withdrawn continuously or intermittently and are solid-gas separated in the solid-gas separation vessels 31 and 32. At this time, the valves 33 and 34 are appropriately controlled to open and close. The polymer particles extracted in this way are discharged to the transport line 25 by the operation of the valve 35 and sent to the second fluidized bed reactor 21 through the transport line 25.
[0021]
In the second fluidized bed reactor 21, the polymer particles extracted from the extraction line 30 from the first fluidized bed reactor 11 through the solid-gas separation vessels 31 and 32 are transferred via the transport line 25. Sent. The transfer line 25 is branched from the supply line 22, and the other end is connected to the upper side of the second fluidized bed reactor 21, and the olefin-containing gas sent from the supply line 22 is supplied to the centrifugal blower 41 or the like. The pressure is raised by the pressure raising means, and the polymer particles extracted from the first fluidized bed reactor 11 are transported along with this gas and introduced into the second fluidized bed reactor 21. . Further, a gas containing a new polymerization monomer (olefin) is supplied from the supply line 22 through the blower 23 to the gas introduction area inside the fluidized bed reactor 21 and below the gas dispersion plate 27 by the transfer line 25. It is blown into the fluidized bed 28 from the gas dispersion plate 27 and discharged from the line 26 at the upper part of the reactor to flow through the reactor, and the solid particles (solid catalyst and polymer produced) are flowed by this gas flow (fluidized gas). By maintaining this state, a fluidized bed (reaction system) 28 is formed. In the present invention, (co) polymerization of olefin is carried out while introducing a liquid phase saturated aliphatic hydrocarbon into a fluidized bed, and the saturated aliphatic hydrocarbon is in a liquid phase state and a gas phase state, or in a gas phase. The mixed liquid is supplied to the fluidized bed.
[0022]
The second fluidized bed reactor 21 is not usually supplied with a new solid catalyst, but if necessary, a new solid catalyst is supplied via an arbitrary place of the fluidized bed reactor, for example, the transport line 25. May be.
In such a fluidized bed 28, polymer particles produced by polymerization of at least one olefin selected from ethylene and olefins having 3 to 20 carbon atoms are continuously or intermittently discharged from the reactor via the extraction line 40. Extracted.
[0023]
Further, the unreacted gaseous olefin, saturated aliphatic hydrocarbon, and the like that have passed through the fluidized bed 28 are reduced in flow rate in the deceleration region 29 provided in the upper part of the second fluidized bed reactor 21. The gas is provided outside the second fluidized bed reactor 21 through a gas outlet provided at the top of the second fluidized bed reactor 21.
Unreacted gaseous olefin, saturated aliphatic hydrocarbon, and the like discharged from the second fluidized bed reactor 21 are cooled by a heat exchanger (cooling device) 24 through a circulation line 26 and supplied to a supply line. 22, and continuously supplied again into the fluidized bed 28 in the second fluidized bed reactor 21 by the blower 23. In the heat exchanger 24, the circulating gas is usually cooled to a temperature near the dew point of the gas. When the circulating gas is cooled to a temperature below the dew point and supplied into the fluidized bed 28, the heat of reaction can be removed by the latent heat of vaporization of the liquid condensate, and the heat removal efficiency in the fluidized bed 28 can be improved. When circulating the circulating gas to the second fluidized bed reactor 21, a part of the circulating gas may be purged from any place in the circulation line 26.
[0024]
Further, after cooling the exhaust gas, for example, with a heat exchanger having a gas-liquid separation function, the saturated aliphatic hydrocarbon in a gas-liquid mixed state is gas-liquid separated, and the separated gas phase is removed from, for example, the supply port The liquid phase may be circulated through the fluidized bed reactor 21 and supplied directly to the lower part of the fluidized bed 28. Alternatively, a part or all of the liquid phase may be supplied to the supply line 22 and circulated to the second fluidized bed reactor 21 together with other supplementary hydrocarbons.
[0025]
As described above, in the first fluidized bed reactor 11, the fluidized gas is circulated at a flow rate that can maintain the fluidized bed 18 in a fluidized state, and in the second fluidized bed reactor 21, the fluidized gas flows. The gasified gas is circulated at a flow rate that can maintain the fluidized bed 28 in a fluidized state.
Specifically, the amount of fluidized gas introduced from the bottom of the reactor from the supply lines 12 and 22 is the minimum fluidization rate of the fluidized bed._mfWhen about 3U_mf~ 50U_mfDegree, preferably about 5U_mf~ 30U_mfIt is desirable that the flow rate be of the order. The fluidized bed can also be stirred mechanically, for example, by using various types of stirrers such as a squid type stirrer, a screw type stirrer, and a ribbon type stirrer.
[0026]
The multi-stage gas phase polymerization apparatus in which two fluidized bed reactors, that is, the first fluidized bed reactor 11 and the second fluidized bed reactor 21 are connected in series has been described. A multi-stage gas phase polymerization apparatus having a vessel can be similarly configured.
In the present invention, at least one olefin selected from ethylene and an α-olefin having 3 to 20 carbon atoms is supplied to the fluidized bed as described above and (co) polymerized. Here, examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and 1-dodecene. 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like.
[0027]
In the present invention, it is preferable to copolymerize ethylene and an α-olefin having 4 to 10 carbon atoms, particularly ethylene and an α-olefin having 5 to 8 carbon atoms. Furthermore, ethylene and 2 or more types of alpha olefins can also be copolymerized.
Further, other polymerizable monomers may be copolymerized with the olefin as necessary, for example, vinyl monomers such as styrene, vinyl chloride, vinyl acetate, vinyl acrylate, methyl methacrylate, tetrafluoroethylene, vinyl ether, acrylonitrile and the like. Conjugated dienes such as butadiene and isoprene, non-conjugated polyenes such as 1,4-hexadiene, dicyclopentadiene and 5-vinyl-2-norbornene, acetylenes such as acetylene and methylacetylene, and aldehydes such as formaldehyde It can also be copolymerized.
[0028]
The monomer consumed in the polymerization can be replenished from any place, and is supplied to the reactor in a normal gas state from a supply port, for example, via a supply line.
In the present invention, a saturated aliphatic hydrocarbon is supplied into the reactor in a gas-liquid two-phase state together with the olefin. Specific examples of the saturated aliphatic hydrocarbon include n-butane, i-butane, n-pentane, i-pentane, hexane, heptane, octane, nonane, decane, 2,2-dimethylpropane, and 2,2-dimethyl. Butane, 2,3-dimethylbutane, 2,2,3-trimethylbutane, 2-methylpentane, 3-methylpentane, 2,2-dimethylpentane, 3,3-dimethylpentane, 2,3-dimethylpentane, 2 Saturation of 4 to 20 carbon atoms such as 1,4-dimethylpentane, 2-methylhexane, 3-methylhexane, 4-methylhexane, 2,3-dimethylhexane, cyclopentane, cyclohexane, methylcyclopentane, dimethylcyclopentane One or two or more selected from aliphatic hydrocarbons are used.
[0029]
Among these, saturated aliphatic hydrocarbons having 4 to 10 carbon atoms, specifically i-pentane, n-pentane, i-butane, n-butane and the like are preferably used.
You may use combining these.
In the present invention, the saturated aliphatic hydrocarbon as described above is fed into the reactor in a liquid phase state and a gas phase state, preferably in a gas-liquid mixed state, to evaporate the liquid phase saturated aliphatic hydrocarbon. To remove the heat of polymerization.
[0030]
In the present invention, in the immediate vicinity of the upstream portion of the gas dispersion plate, when the inner radius of the straight body portion of the fluidized bed reactor is 1, the center of the straight body portion is the starting point, and 0.7 to 1.. The concentration of saturated aliphatic hydrocarbons in the liquid phase at the periphery of the trunk at 0 position (C₁), And the concentration of saturated aliphatic hydrocarbons in the liquid phase at the center of the trunk that is less than 0.7 from the center (C₂) And C₁> C₂, Preferably C₁> C₂× 1.5, more preferably C₁> C₂Olefin is (co) polymerized under the conditions satisfying × 2.0.
[0031]
When (co) polymerizing olefins under such conditions, it becomes possible to selectively remove the heat at the periphery of the fluidized bed reactor, where the problem of heat generation is significant, and the generation of heat spots is suppressed. Further, by setting the above conditions, it is possible to efficiently remove heat by concentrating the saturated hydrocarbon in the liquid phase on the periphery of the fluidized bed reactor, so the total saturated hydrocarbon amount in the liquid phase And the burden on equipment such as a blower for circulating the polymerization gas can be reduced.
[0032]
In order to make the concentration of the saturated aliphatic hydrocarbon in the liquid phase at the periphery of the trunk higher than the concentration of the saturated aliphatic hydrocarbon in the center of the trunk, the gas velocity at the periphery of the trunk It is effective to make the speed faster than the gas velocity at the center of the trunk.
The concentration of the saturated aliphatic hydrocarbon in the liquid phase in the fluidized bed reactor is measured as follows.
[0033]
That is, a gas sample was collected by installing a sampling nozzle at the lower part of the dispersion plate, and a liquid ratio in a saturated state under pressure and temperature conditions at the lower part of the dispersion plate was calculated from the gas composition to obtain a mist concentration.
In the present invention, in the immediate vicinity of the upstream portion of the gas dispersion plate, when the inner radius of the straight body portion of the fluidized bed reactor is 1, the center of the straight body portion is the starting point, and 0.7 to 1.. The average gas flow velocity (V₁), And an average gas flow velocity (V) at the center of the trunk that is less than 0.7 from the center.₂) And V₁> V₂, Preferably V₁> V₂× 1.5, more preferably V₁> V₂It is preferable to (co) polymerize the olefin under conditions that satisfy x2.0.
[0034]
When (co) polymerizing olefins under these conditions, mist droplets with a higher specific gravity than the gas phase sink in the central part where the flow velocity is small, so that the rim drops at the periphery of the barrel where the flow velocity is relatively high. As a result, the concentration of the saturated aliphatic hydrocarbon in the liquid phase at the periphery of the trunk is higher than the concentration of the saturated aliphatic hydrocarbon in the liquid at the center of the trunk.
[0035]
In addition, the average gas flow rate of the straight body part of the fluidized bed reactor is measured as follows.
That is, a variable insertion length type Pitot tube is installed at the lower part of the gas dispersion plate, and the gas flow rate at each predetermined position is changed while gradually changing the insertion length of the Pitot tube from the center of the straight body part to the peripheral part. taking measurement. The average gas flow velocity at the central portion and the peripheral portion is obtained from the obtained radial gas flow velocity distribution.
When the gas flow velocity cannot be measured, the gas flow velocity is calculated using a generally known equation for calculating the pressure loss of the fluidized bed dispersion plate as shown in Equation 1.
[0036]
[Expression 1]

[0037]
A method for setting the average gas flow rate in the straight body portion in the fluidized bed reactor as described above will be described later.
In the fluidized bed, the polymerization varies depending on the type and copolymerization ratio of the olefin, the amount of saturated aliphatic hydrocarbon, the gas flow rate, etc., but the polymerization pressure is usually 1-100 kg / cm.², Preferably 2-40 kg / cm²Within the range of the polymerization temperature T_RIs the reactor exhaust gas temperature (≈T_out) And is generally performed within a range of 20 to 130 ° C, preferably 50 to 120 ° C, more preferably 70 to 110 ° C.
[0038]
The above copolymerization can be carried out in the presence of a molecular weight regulator such as hydrogen, if necessary, and can be supplied from any location.
The olefin-based polymer produced as described above is usually dried after being continuously or intermittently extracted from the lower part of the reactor. The saturated aliphatic hydrocarbons as described above are non-polymerizable and will not be consumed by the polymerization, and the saturated aliphatic hydrocarbons gasified in the reaction system are discharged from the line together with unreacted polymerization monomers and usually cooled. Although it is circulated to the post-reactor, the non-evaporated component is usually contained in the produced olefin polymer and extracted from the reactor, so that the reduced amount can be supplied from any place.
[0039]
The gas discharged through the line from the reactor as described above is usually cooled in a heat exchanger, and a part of the saturated aliphatic hydrocarbon contained in the gas is liquefied to form a gas-liquid mixed state. Thereafter, it is circulated in the reactor.
When the exhaust gas is circulated through the reactor in this way, a part of the exhaust gas may be purged. The gas discharged from the reactor usually contains unreacted polymerization monomer, hydrogen gas, inert gas and the like in addition to the saturated aliphatic hydrocarbon.
[0040]
In the present invention, when the exhaust gas is circulated to the reactor in this way, the saturated aliphatic hydrocarbon cooled by the heat exchanger and brought into the gas-liquid mixed state is directly supplied from the supply port to the reactor as the fluidized gas. It is preferable to circulate.
Further, after cooling the exhaust gas, for example, with a heat exchanger having a gas-liquid separation function, the saturated aliphatic hydrocarbon in a gas-liquid mixed state is gas-liquid separated, and the separated gas phase is removed from, for example, the supply port It may be circulated through the fluidized bed reactor, and part or all of the liquid phase may be supplied to the supply line and circulated to the fluidized bed reactor together with other supplementary hydrocarbons.
[0041]
In the present invention, the molecular weight of the resulting olefin polymer can be adjusted by changing the polymerization conditions such as the polymerization temperature, or can be adjusted by controlling the amount of hydrogen (molecular weight regulator) used. it can.
C in the fluidized bed reactor₁> C₂, V₁> V₂As a method of satisfying the conditions,
(1) A fluidized bed reactor having means for changing the direction of all or part of the flow of gas supplied to the gas introduction zone, and saturated aliphatic hydrocarbons are included in the gas supplied to the gas introduction zone. A method for making it contained in a gas-liquid mixed state,
(2) It has means for giving the gas supplied to the gas introduction zone a momentum in the circumferential direction of the straight body portion, and saturated aliphatic hydrocarbons are gas-liquid to the gas supplied to the gas introduction zone. How to be included in a mixed state,
(3) There is a method of supplying a saturated aliphatic hydrocarbon in a liquid phase state from a supply port provided at a peripheral edge portion of the gas dispersion plate that is at a position of 0.7 to 1.0 from the center of the gas dispersion plate.
[0042]
First, the method (1) will be described.
As a means for carrying out the method (1), for example, inside the reactor, the gas flow to the gas dispersion plate is distributed to the gas introduction area below the gas dispersion plate and the lower part of the gas dispersion plate There is a method of providing a diffuser plate for making the gas flow turbulent. One embodiment of a gas phase fluidized bed reactor provided with such a diffuser plate is shown in FIGS. 3 and 4 show the case where the method (1) is applied to the fluidized bed reactor shown in FIG. 1, but even in the multistage gas phase polymerization apparatus as shown in FIG. It can be configured similarly.
[0043]
3 and 4 partially show an example of a gas-phase fluidized bed reactor equipped with a diffuser plate. The diffuser plate 42 of the fluidized bed reactor 11 is a horizontal plate that is arranged to be separated from the lowermost part of the fluidized bed reactor 11 to some extent. The air diffuser plate 42 is supported by a tip portion of the supply pipe 9 that faces the inside of the fluidized bed polymerization vessel 11.
A central hole 42a is formed at the center of the diffuser plate 42, and the lower end of the diffuser plate 42 is in contact with the tip of the supply pipe 9 so as to surround the central hole 42a. In addition, a plurality of longitudinal slits 9a, 9a,... Are arranged at appropriate intervals in the circumferential direction of the supply pipe 9 (for example, at equal intervals) at the portion of the supply pipe 9 facing the fluidized bed polymerization vessel 11. ).
[0044]
Therefore, the gas sent from the supply pipe 9 to the fluidized bed polymerization vessel 11 passes through the central hole 42a and the slit 9a of the diffuser plate 42 as shown in FIGS. And a peripheral annular flow indicated by an arrow 47 and reflux in the gas introduction zone 11 b below the gas dispersion plate 17 of the fluidized bed reactor 11.
[0045]
Specifically, the center upward flow 45 flows from the central hole 42a of the diffuser plate 42 to the upper side thereof, and then drops like a fountain radially. The peripheral annular flow 47 is a hole in the supply pipe 9. 9b (which can also be said to be the inlet of the fluidized bed reactor 11), starting from there, a circular arc is formed along the inner wall surface of the hemispherical bottom portion 11a of the fluidized bed reactor 11 through the slits 9a, 9a,. It becomes a flow like drawing.
[0046]
As a result, both flows are mixed, and the fluidized-bed reaction again from the fine holes 17a of the gas dispersion plate 17 without causing the powdery polymer to settle and stay on or adhere to the inner wall surface of the gas introduction region 11b. It reaches the fluidized bed 18 of the vessel 11.
In the present invention, the diffuser plate is preferably placed entirely perpendicular to the axis of the fluidized bed reactor.
[0047]
In addition, the diffuser plate may be provided substantially parallel to the gas dispersion plate as shown in FIG. 3, or may be provided so as to be concave with respect to the gas dispersion plate, or may be convex with respect to the gas dispersion plate. It can also be provided.
In the present invention, the height of the gas introduction area (height from the opening of the introduction pipe 9 to the lower surface of the gas dispersion plate) is 1.5 or less, preferably 0.7 to 1.0 with respect to the diameter. Is preferred.
[0048]
In addition, the diffuser plate has an area (A₂) And the area (A₁It is desirable that the ratio of
0.1 <A₂/ A₁<0.75
and
0.5 <(d_o-D_e) / 2h <5
(Where d_oIs the diameter of the diffuser and d_eIs the diameter (inner diameter) of the introduction pipe, and h is the minimum distance from the lower outer edge of the diffuser plate to the gas introduction zone wall. )
At this time, it is preferable that the velocity head (Hv) based on the total flow area of the diffuser plate satisfies the following formula.
[0049]
Hv> 0.34 kPa
The diffuser plate described above is provided with a hole in the center, but the diffuser plate used in the present invention may have an inclined upper surface. FIG. 5 shows another embodiment of such a gas phase fluidized bed reactor provided with a diffuser plate having an inclined upper surface. FIG. 5 shows the case where the method (1) is applied to the fluidized bed reactor shown in FIG. 1, but the same configuration is applied to the multistage gas phase polymerization apparatus as shown in FIG. it can.
[0050]
The diffuser plate 52 of the fluidized bed reactor 11 is positioned below the gas dispersion plate 17. The diffuser plate 52 flows the flow into the gas dispersion plate 17 in the gas phase sent from the introduction pipe 9 which is a part of the gas phase circulation system to the inlet 9 b of the fluidized bed reactor 11. It is an apparatus for distributing along the inner wall surface of the hemispherical bottom portion 11a, and has a hollow and closed cone shape.
[0051]
In this embodiment, the diffuser plate 52 includes an upper conical portion 51 and a lower flat conical portion 53 having a shape such that a portion corresponding to the bottom surface of the upper conical portion 51 protrudes downward. And a cone (cone) set with the following dimensions.
(I) The shape of the vertical cross section of the upper cone-shaped part 51 is an isosceles triangle, and the apex angle θ1 is 90 °. The shape of the vertical cross section of the lower flat cone-shaped portion 13 is also an isosceles triangle, and the apex angle θ2 is 150 °. However, it is not limited to these angles, and θ1 may be set in the range of 80 ° to 120 °, and θ2 may be set in the range of 120 ° to 160 °.
(Ii) The maximum diameter D2 (see FIG. 5) of the diffuser plate is 1.3 · D1.
[0052]
However, D1 shows the internal diameter of the pipe | tube which comprises the said gaseous-phase circulation system, D2 is not limited to said value, What is necessary is just the range of 1.1 * D1-1.5 * D1.
(Iii) The distance H1 between the diffuser plate and the bottom of the fluidized bed reactor is obtained by the following equation, and is a value obtained when the coefficient k is 1.0.
H1 = k · (D12 · π / 4) / (D2 · π)
However, the coefficient k is 0.8 to 1.2.
[0053]
In FIG. 5, reference numeral 54 indicates the upper surface of the diffuser plate 52 (the substantially conical surface of the upper conical portion 51). On this upper surface 54, the powdery polymer introduced from the inlet 9b of the fluidized bed reactor 11 and soared by the surrounding annular flow 47 settles. Further, it is preferable that the upper surface 54 is subjected to a bug finish (mirror finish) because the powdery polymer accumulated on the upper surface 54 becomes more slippery.
[0054]
The upper surface 54 has a plurality of holes or at least double holes (not shown) that are not shown. Then, a purge line is arranged on the diffuser plate 52 with a monomer, for example, ethylene (not shown), that is, a fine pressure is applied, so that the powdered polymer does not enter the diffuser plate 52 from the plurality of holes. I have to.
The diffuser plate 52 having an inclined upper surface is not limited to the shape described above, and the diffuser plate 52 may have a concave arcuate side when viewed in its vertical cross section. Good. The overall shape of the diffuser plate in this case can be said to be a trumpet shape corresponding to the bell (commonly called “morning glory”) portion of a wind instrument, for example.
[0055]
In addition, the diffuser plate having an inclined upper surface may be one in which the side when viewed in its vertical cross section is a convex arc curve. In this case, the entire shape of the diffuser plate can be said to be a dome shape.
Furthermore, the diffuser plate whose upper surface is inclined may be such that its side is a straight line when viewed in its vertical cross section. It can be said that the entire shape of the diffuser plate in this case is a conical shape.
[0056]
In addition, the inclined body may be a polygonal pyramid whose overall shape is close to a conical shape.
Next, the method (2) will be described.
In the method (2), a fluidized bed reactor having means for imparting a momentum in the circumferential direction of the straight body to the fluid supplied to the fluidized bed is used at the bottom of the gas dispersion plate, and the inside of the fluidized bed reactor A saturated aliphatic hydrocarbon is introduced into the gas-liquid mixed state.
[0057]
As a means for giving the momentum in the circumferential direction, a supply port of a supply pipe for supplying a gas containing a saturated aliphatic hydrocarbon in a gas-liquid mixed state to the gas introduction region is the center of the straight body portion of the fluidized bed reactor. There is a method in which the gas is blown in such a manner that the gas is provided off-axis and has an angle of 1 degree or more with respect to a line connecting the center of the straight body portion and the center of the supply port. When the inner radius of the straight body part of the fluidized bed reactor is 1, the supply port is preferably located at a position of 0.2 to 1.0 from the center of the straight body part as a starting point. The blowing direction is preferably in the range of 30 to 150 degrees with respect to a line connecting the center of the straight body portion and the center of the supply port.
[0058]
As a means for giving the momentum in the circumferential direction, there is a method of providing a rectifying plate that gives the momentum in the circumferential direction to the introduced gas in the vicinity of the supply port in the gas introduction region.
Next, the method (3) will be described.
In the method (3), a saturated aliphatic hydrocarbon in a liquid phase is supplied from a supply port provided at the peripheral edge of the gas dispersion plate that is located at a position of 0.7 to 1.0 from the center of the gas dispersion plate. At this time, saturated aliphatic hydrocarbons in a gas phase can be supplied from a supply port provided at the center of the gas dispersion plate that is less than 0.7 from the center. The supply port provided on the peripheral edge of the dispersion plate may be provided on either the upstream side or the downstream side of the gas dispersion plate. From the viewpoint of appropriately dispersing the liquid phase, the supply port is provided upstream of the gas dispersion plate. The side is preferred.
[0059]
In this method, a part of the saturated aliphatic hydrocarbon contained in the circulating gas is separated in the liquid phase using a cooler or the like, and the obtained liquid phase saturated aliphatic hydrocarbon is provided at the periphery of the gas dispersion plate. While supplying from a supply port, supplying the circulation gas which isolate | separated a part of saturated aliphatic hydrocarbon to contain from the supply port provided in the gas dispersion plate center part is performed normally. In the present invention, at least a part of the liquid-phase saturated aliphatic hydrocarbon supplied from the supply port provided at the peripheral edge of the gas dispersion plate can be supplied from the outside of the fluidized bed reactor. At least a part of the saturated aliphatic hydrocarbons in the gas phase supplied from the supply port provided in can be supplied from the outside of the fluidized bed reactor.
[0060]
(catalyst)
In the present invention, the copolymerization as described above can be carried out using a wide variety of catalysts known as ethylene polymerization catalysts such as Ziegler type titanium catalysts and Philip type chromium oxide catalysts. It is desirable to use a metallocene catalyst.
[0061]
Specifically, the metallocene catalyst preferably used in the present invention is, for example,
(A) a metallocene compound of a transition metal selected from Group IVB of the periodic table,
and
(B) (B-1) an organoaluminum oxy compound,
(B-2) an organoaluminum compound, and
(B-3) Compounds that react with the metallocene compound (A) to form ion pairs
At least one compound selected from the group consisting of
[0062]
((A) metallocene compound)
The metallocene compound (A) of a transition metal selected from Group IVB of the periodic table is specifically represented by the following formula (i).
MLx (i)
Wherein M is a transition metal selected from Zr, Ti, Hf, V, Nb, Ta and Cr, L is a ligand coordinated to the transition metal, and at least one L is cyclopentadi L is a ligand having an enyl skeleton, and L other than the ligand having a cyclopentadienyl skeleton is a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, or a trialkyl. Silyl group or SO_ThreeR is a R group (where R is a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent such as halogen), and x is a valence of the transition metal. )
Examples of the ligand having a cyclopentadienyl skeleton include, for example, a cyclopentadienyl group, a methylcyclopentadienyl group, a dimethylcyclopentadienyl group, a trimethylcyclopentadienyl group, a tetramethylcyclopentadienyl group, Pentamethylcyclopentadienyl, ethylcyclopentadienyl, methylethylcyclopentadienyl, propylcyclopentadienyl, methylpropylcyclopentadienyl, butylcyclopentadienyl, methylbutylcyclopentadi Examples include an alkyl-substituted cyclopentadienyl group such as an enyl group and a hexylcyclopentadienyl group, an indenyl group, a 4,5,6,7-tetrahydroindenyl group, a fluorenyl group, and the like. These groups may be substituted with a halogen atom, a trialkylsilyl group or the like.
[0063]
Of these, an alkyl-substituted cyclopentadienyl group is particularly preferable.
Specific examples of the ligand other than the ligand having a cyclopentadienyl skeleton include halogen, fluorine, chlorine, bromine, iodine, and the like. The hydrocarbon group having 1 to 12 carbon atoms is methyl. Alkyl groups such as ethyl, propyl, isopropyl and butyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; aryl groups such as phenyl and tolyl groups; aralkyl groups such as benzyl and neophyll groups; Examples of the alkoxy group include a methoxy group, an ethoxy group, and a butoxy group. Examples of the aryloxy group include a phenoxy group._ThreeExamples of the R group include a p-toluene sulfonate group, a methane sulfonate group, and a trifluoromethane sulfonate group.
[0064]
When the compound represented by the above general formula contains two or more groups having a cyclopentadienyl skeleton, the two groups having a cyclopentadienyl skeleton are alkylene groups such as ethylene and propylene, isopropyl It may be bonded via a substituted alkylene group such as lidene or diphenylmethylene, a silylene group or a dimethylsilylene group, a substituted silylene group such as a diphenylsilylene group or a methylphenylsilylene group.
[0065]
The metallocene compound containing a ligand having such a cyclopentadienyl skeleton is more specifically represented by the following formula (ii) when the valence of the transition metal is 4, for example.
R² _kR^Three _lR^Four _mR^Five _nM (ii)
Wherein M is the transition metal and R²Is a group (ligand) having a cyclopentadienyl skeleton, and R^Three, R^FourAnd R^FiveIs a group having a cyclopentadienyl skeleton or another group as described above, k is an integer of 1 or more, and k + l + m + n = 4. )
In the present invention, this formula R² _kR^Three _lR^Four _mR^Five _nIn M, R², R^Three, R^FourAnd R^FiveAt least two of them, eg R²And R^ThreeHowever, a metallocene compound which is a group (ligand) having a cyclopentadienyl skeleton is preferably used. These groups having a cyclopentadienyl skeleton may be bonded via an alkylene group, a substituted alkylene group, a silylene group, a substituted silylene group, or the like.
[0066]
Specific examples of the metallocene compounds as described above include, when M is zirconium, bis (cyclopentadienyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dibromide, bis (cyclopentadienyl) dimethylzirconium, Bis (cyclopentadienyl) diphenylzirconium, bis (cyclopentadienyl) dibenzylzirconium, bis (cyclopentadienyl) zirconium bis (methanesulfonate), bis (cyclopentadienyl) zirconium bis (p-toluenesulfo Nato), bis (cyclopentadienyl) zirconium bis (trifluoromethanesulfonate), bis (methylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium dichloride, bi (Ethylcyclopentadienyl) zirconium dichloride, bis (methylethylcyclopentadienyl) zirconium dichloride, bis (propylcyclopentadienyl) zirconium dichloride, bis (methylpropylcyclopentadienyl) zirconium dichloride, bis (butylcyclopenta Dienyl) zirconium dichloride, bis (methylbutylcyclopentadienyl) zirconium dichloride, bis (trimethylcyclopentadienyl) zirconium dichloride, bis (indenyl) zirconium dichloride, bis (indenyl) zirconium dibromide, bis (4,5, 6,7-tetrahydroindenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride Lido, ethylenebis (indenyl) zirconium dibromide, ethylenebis (indenyl) dimethylzirconium, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-methylcyclopentadienyl) zirconium dichloride, dimethyl Silylenebis (cyclopentadienyl) zirconium dichloride, dimethylsilylenebis (methylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, dimethylsilylenebis ( 2-Methylindenyl) zirconium dichloride, dimethylsilylenebis (2-methyl-4-isopropyl) Indenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl - fluorenyl) zirconium dichloride, and diphenyl (indenyl) zirconium dichloride.
[0067]
In the above examples, the disubstituted product of the cyclopentadienyl ring includes 1,2- and 1,3-substituted products, and the trisubstituted product includes 1,2,3- and 1,2,4-substituted products. . Alkyl groups such as propyl and butyl include isomers such as n-, i-, sec- and tert-.
In addition, in the zirconium metallocene compound as described above, compounds in which zirconium is replaced with titanium, hafnium, vanadium, niobium, tantalum, or chromium can also be exemplified.
[0068]
In the present invention, a zirconium metallocene compound having a ligand containing at least two cyclopentadienyl skeletons is preferably used as the metallocene compound (A). Two or more of these compounds may be used in combination.
((B-1) Organoaluminum oxy compound)
(B-1) The organoaluminum oxy compound may be a conventionally known benzene-soluble aluminoxane, or a benzene-insoluble organoaluminum oxy compound as disclosed in JP-A-2-276807. Good.
[0069]
The aluminoxane may contain a small amount of an organometallic component. Further, after removing the solvent or the unreacted organoaluminum compound from the recovered aluminoxane solution by distillation, it may be used by re-dissolving in the solvent.
Specific examples of the organoaluminum compound used for producing the aluminoxane include those described later as the organoaluminum compound (B-2), and these can be used in combination of two or more. Of these, trialkylaluminum and tricycloalkylaluminum are particularly preferred.
[0070]
The benzene-insoluble organoaluminum oxy compound has an Al component dissolved in benzene at 60 ° C. of 10% or less, preferably 5% or less, particularly preferably 2% or less in terms of Al atom, and is insoluble or difficult to benzene. It is soluble.
The solubility of such an organoaluminum oxy compound in benzene is determined by suspending the organoaluminum oxy compound corresponding to 100 milligrams of Al in 100 ml of benzene, mixing at 60 ° C. for 6 hours with stirring, and then attaching a jacket. Using a G-5 glass filter, hot filtration was performed at 60 ° C., and the solid portion separated on the filter was washed four times with 50 ml of benzene at 60 ° C., and the Al atoms present in the total filtrate were removed. It is determined by measuring the abundance (x mmol) (x%). In the present invention, two or more organic aluminum oxy compounds (B-1) may be used in combination.
[0071]
((B-2) Organoaluminum compound)
The organoaluminum compound (B-2) used in the present invention is represented, for example, by the following general formula (iii).
R¹ _nAlX_3-n       ... (iii)
(In formula (iii), R¹Is a hydrocarbon group having 1 to 12 carbon atoms, X is a halogen atom or a hydrogen atom, and n is 1 to 3. )
In the general formula (iii), R¹Is a hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group, a cycloalkyl group or an aryl group, and specifically includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an isobutyl group, a pentyl group. Hexyl group, octyl group, cyclopentyl group, cyclohexyl group, phenyl group, tolyl group and the like.
[0072]
Specific examples of such organoaluminum compound (B-2) include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum; alkenylaluminum such as isoprenylaluminum, dimethylaluminum chloride, Dialkylaluminum halides such as diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride; alkylaluminum sesquichlorides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride; methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum dichloride Such as Le Kill dihalide diethyl aluminum hydride, alkyl aluminum hydride such as diisobutylaluminum hydride and the like.
[0073]
Further, as the organoaluminum compound (B-2), a compound represented by the following general formula (iv) can also be used.
R¹ _nAlY_3-n      … (Iv)
(In formula (iv), R¹Is the same as above, and Y is -OR.²Group, -OSiR^Three _ThreeGroup, -OAlR^Four ₂Group, -NR^Five ₂Group, -SiR⁶ _ThreeGroup or -N (R⁷) AlR⁸ ₂A group, n is 1-2, R², R^Three, R^FourAnd R⁸Is a methyl group, an ethyl group, an isopropyl group, an isobutyl group, a cyclohexyl group, a phenyl group, and the like;^FiveIs a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, a phenyl group, a trimethylsilyl group, etc., and R⁶And R⁷Is a methyl group, an ethyl group or the like. )
[0074]
Of these, trialkylaluminum is preferable, and triisobutylaluminum is particularly preferable. Two or more organoaluminum compounds (B-2) may be used in combination.
((B-3) a compound that reacts with the metallocene compound (A) to form an ion pair)
Examples of the compound (B-3) that forms an ion pair by reacting with the metallocene compound (A) used in the present invention include JP-A-1-501950, JP-A-1-503636, and JP-A-3-179005. No. 3, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, US-5321106 and the like, and Lewis acids, ionic compounds and carborane compounds. Can do.
[0075]
Examples of Lewis acids include triphenylboron, tris (4-fluorophenyl) boron, tris (p-tolyl) boron, tris (o-tolyl) boron, tris (3,5-dimethylphenyl) boron, and tris (pentafluorophenyl). ) Boron, MgCl₂, Al₂O_Three, SiO₂-Al₂O_ThreeAnd so on.
Examples of ionic compounds include triphenylcarbenium tetrakis (pentafluorophenyl) borate, tri-n-butylammonium tetrakis (pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, ferrocenium tetra. And (pentafluorophenyl) borate.
[0076]
Examples of carborane compounds include dodecaborane, 1-carbaundecaborane, bis-n-butylammonium (1-carbedodeca) borate, tri-n-butylammonium (7,8-dicarboundaca) borate, tri-n-butylammonium (trideca Hydride-7-carboundeca) borate and the like.
[0077]
These can also be used in combination of two or more. In the present invention, as the cocatalyst component (B), at least one compound selected from the above components (B-1), (B-2) and (B-3) is used, and these are appropriately combined. Can also be used. Among these, it is desirable to use at least (B-2) or (B-3) as the cocatalyst component (B).
[0078]
(Solid catalyst)
In the present invention, it is preferable to use a catalyst containing the metallocene catalyst component and the cocatalyst component as described above, but these catalyst components are usually used as a carrier-supported catalyst (solid catalyst) by contacting with a particulate carrier compound. Is preferred.
As the carrier compound, a granular or fine particle solid having a particle size of 10 to 300 μm, preferably 20 to 200 μm is used. The specific surface area of this carrier is usually 50 to 1000 m.²/ G, and the pore volume is 0.3 to 2.5 cm.^Three/ G is desirable.
[0079]
As such a carrier, a porous inorganic oxide is preferably used, specifically, SiO.₂, Al₂O_Three, MgO, ZrO₂TiO₂, B₂O_Three, CaO, ZnO, BaO, ThO₂Or mixtures containing these, for example SiO₂-MgO, SiO₂-Al₂O_Three, SiO₂-TiO₂, SiO₂-V₂O_Five, SiO₂-Cr₂O_Three, SiO₂-TiO₂-MgO or the like is used. Among these, SiO₂And / or Al₂O_ThreeThe main component is preferred.
[0080]
The inorganic oxide contains a small amount of Na₂CO_Three, K₂CO_Three, CaCO_Three, MgCO_Three, Na₂SO_Four, Al₂(SO_Four)_Three, BaSO_Four, KNO_Three, Mg (NO_Three)₂, Al (NO_Three)_Three, Na₂O, K₂O, Li₂Carbonate such as O, sulfate, nitrate, and oxide component may be contained.
Moreover, an organic compound can also be used as a support | carrier, for example, it produces | generates by making (alpha) -olefin of 2-14 carbon atoms, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, a main component. A polymer, or a copolymer or copolymer produced mainly from vinylcyclohexane or styrene can be used.
[0081]
The contact between the carrier and each of the above components is usually carried out at a temperature of -50 to 150 ° C, preferably -20 to 120 ° C for 1 minute to 50 hours, preferably 10 minutes to 25 hours.
The solid catalyst prepared as described above has 5 × 10 5 metallocene compounds (A) as transition metal atoms per gram of support.^-6~ 5x10^-FourGram atoms, preferably 10^-Five~ 2x10^-FourIn an amount of gram atoms, component (B) is 10 as aluminum or boron atoms per gram of support.^-3~ 5x10^-2Gram atoms, preferably 2 × 10^-3~ 2x10^-2It is preferably supported in the amount of gram atoms.
[0082]
Furthermore, in the present invention, the solid catalyst as described above can be used in the polymerization as it is, but it can also be used after preliminarily polymerizing this olefin with a solid catalyst to form a prepolymerized catalyst.
(polymerization)
In the present invention, the solid catalyst or the prepolymerized catalyst is transition metal / liter (polymerization volume), usually 10^-8-10^-3Gram atom / liter, or even 10^-7-10^-FourIt is desirable to be used in an amount of gram atoms / liter.
[0083]
When using a prepolymerization catalyst, component (B) may or may not be used, but the atomic ratio of aluminum or boron in component (B) to transition metal in the polymerization system (Al or B / transition metal) 5 to 300, preferably 10 to 200, and more preferably 15 to 150.
In the present invention, the olefin polymer can be obtained in the form of granular particles by gas phase polymerization as described above. The average particle size of the particles is about 250 to 3000 μm, preferably about 400 to 1500 μm.
[0084]
In the present invention, the density (ASTM D150 E) is particularly 0.865 to 0.925 g / cm as the olefin polymer.^Three, Preferably 0.880 to 0.920 g / cm^ThreeIt is preferable to produce a linear low density polyethylene which is a unit of 87.0 to 97.6 mol%, preferably 90.0 to 96.8 mol% derived from ethylene. It is desirable that the unit derived from an olefin having 4 to 10 carbon atoms is contained in an amount of 13.0 to 2.4 mol%, preferably 10.0 to 3.2 mol%.
[0085]
In the olefin polymer, the unit derived from other copolymerization monomers such as polyenes is 10% by weight or less, preferably 5% by weight or less, particularly preferably 3% by weight, as long as the object of the present invention is not impaired. It may be included in the following amounts.
[0086]
【The invention's effect】
According to the present invention, gas phase polymerization of olefins using a fluidized bed reactor can be performed with excellent heat removal efficiency, and polymer sheeting or melting due to thermal uneven distribution is less likely to occur during the production of olefin polymers.
[0087]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
[0088]
[Example 1]
(Preparation of solid catalyst component)
Silica (SiO2) dried at 250 ° C. for 10 hours₂) 10 kg was suspended in 154 liters of toluene and then cooled to 0 ° C. To this suspension, 50.5 liters of a toluene solution of methylaluminoxane (Al = 1.52 mol / liter) was added dropwise over 1 hour while maintaining the temperature of the suspension at 0 to 5 ° C. After maintaining at 0 ° C. for 30 minutes, the temperature was raised to 95 ° C. over 1.5 hours and maintained at 95 ° C. for 4 hours.
[0089]
Thereafter, the temperature was lowered to 60 ° C., and the supernatant was removed by decantation. The solid catalyst component thus obtained was washed twice with toluene and then resuspended in 100 liters of toluene to a total volume of 160 liters.
To the obtained suspension, 22.0 liters of a toluene solution of bis (1,3-n-butylmethylcyclopentadienyl) zirconium dichloride (Zr = 25.7 mmol / liter) was added at 80 ° C. over 30 minutes. The solution was added dropwise and kept at 80 ° C. for 2 hours. Thereafter, the supernatant was removed and washed twice with hexane to obtain a solid catalyst component containing 3.2 mg of zirconium per 1 g of silica.
[0090]
(Preliminary polymerization of solid catalyst components)
Into a 350 liter reactor sufficiently purged with nitrogen, 7.0 kg of the above solid catalyst component was charged, and hexane was charged to obtain a hexane suspension having a total volume of 285 liters.
After cooling the system to 10 ° C, ethylene was flowed at 8 Nm.^Three/ Hr for 5 minutes into a solid catalyst component hexane suspension. During this time, the temperature in the system was maintained at 10 to 15 ° C.
[0091]
After the supply of ethylene was temporarily stopped, 2.4 mol of triisobutylaluminum and 1.2 kg of 1-hexene were supplied, and after the inside of the system was sealed, the supply of ethylene was resumed, and the flow rate was 8 Nm.^ThreeAfter supplying for 15 minutes at / hr, the flow rate is 2 Nm^Three/ Hr, the pressure in the system is 0.8 kg / cm²-G. During this time, the system temperature rose to 35 ° C.
[0092]
Then, while controlling the temperature in the system to 32 to 35 ° C., ethylene was reduced to 4 Nm.^Three/ Hr was supplied for 3.5 hours. During this time, the pressure in the system is 0.7 to 0.8 kg / cm.²-Hold on G. Next, the system was purged with nitrogen, the supernatant was removed, and then washed twice with hexane. The supernatant liquid after preliminary polymerization was colorless and transparent.
As described above, a prepolymerized catalyst containing 3 g of the prepolymer per 1 g of the solid catalyst component was obtained. This prepolymerized catalyst (prepolymer) had an intrinsic viscosity [η] measured in decalin at 135 ° C. of 2.1 dl / g and a 1-hexene unit content of 4.8% by weight. The shape of the prepolymerized catalyst is good and the bulk density is 0.4 g / cm.^ThreeMet.
[0093]
(Gas phase polymerization)
Gas phase polymerization was performed using a continuous fluidized bed reactor as shown in FIG.
That is, the prepolymerized catalyst obtained as described above was continuously supplied in an amount of 67.8 g / hr, and ethylene was continuously polymerized in the presence of isopentane to obtain polyethylene (PE).
[0094]
As shown in Table 1, this polymerization is performed at a polymerization temperature of 80 ° C., a polymerization pressure of 1.7 MPa-G (gauge pressure), an ethylene partial pressure of 1.1 MPa, a superficial velocity of 0.60 m / s, in a deceleration region of the reactor. This was performed under the condition of an isopentane concentration of 20 mol% in the gas (TOP gas). During this polymerization, the average molecular weight of the TOP gas is 38.0 g / mol and the density is 25.9 kg / m.^ThreeMet. The dew point of the TOP gas is 78.1 ° C., the temperature on the circulating gas outlet side of the heat exchanger is 75.0 ° C., and the condensate ratio on the circulating gas outlet side is 3.3% by weight. It was. The TOP gas is a mixture of ethylene, nitrogen, hydrogen, 1-hexene and isopentane and has an average molecular weight of 38 g / mol.
[0095]
As shown in Table 1, the polyethylene obtained as described above has a density (ASTM D1505) of 0.918 kg / m.^ThreeMFR (ASTM D1238, 190 ° C., load 2.16 kg) was 3.8 g / 10 min. The polymerization amount per unit volume (STY; Space Time Yield) is 200 kg / h · m.^ThreeThe catalytic activity was 3500 g-PE / g-Bear catalyst. In addition, bulk polyethylene was not generated.
[0096]
[Example 2, Comparative Example 1 and Comparative Example 2]
In Example 1, polyethylene (PE) was obtained in the same manner as in Example 1 except that the polymerization of ethylene was changed to the conditions shown in Table 1.
Table 1 shows the conditions and polymerization results of Examples 1 and 2 and Comparative Examples 1 and 2.
For the mist concentration at the upstream of the gas dispersion plate, a sampling nozzle is installed at the bottom of the dispersion plate and a gas sample is taken, and the liquid ratio in the saturated state under the pressure and temperature conditions at the bottom of the dispersion plate is calculated from the gas composition. The mist concentration was used. That is, when a radial distribution occurs in the mist concentration, the gas collected at the peripheral portion has a higher isopentane and 1-hexene concentration than the gas collected at the central portion.
[0097]
[Table 1]

[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of a polymerization process by a polyolefin production method according to the present invention.
FIG. 2 is a schematic explanatory diagram of another circulation process in the method for producing polyolefin according to the present invention.
FIG. 3 is a vertical sectional view showing an example of a diffuser plate used in the present invention.
4 is an enlarged view of a main part of FIG. 3;
FIG. 5 is a vertical sectional view showing another example of a diffuser plate used in the present invention.
[Explanation of symbols]
11 ... Fluidized bed reactor
11a ... Straight trunk
11b ... Gas introduction area
17 ... Gas dispersion plate
18 ... Fluidized bed
42 ... Diffuser
52 ... Diffuser

Claims (5)

Using a fluidized bed reactor having a gas dispersion plate having a large number of gas passage holes in the lower portion of the straight body portion, and including at least a polymerization monomer supplied to a gas introduction zone inside the fluidized bed reactor and below the gas dispersion plate Gas is blown into the fluidized bed through the gas dispersion plate and discharged from the upper part of the reactor to circulate in the reactor. By this gas flow, the solid particles are brought into a fluidized state and one or more olefins are vaporized. In (co) polymerization at
A saturated aliphatic hydrocarbon is introduced into the fluidized bed in a liquid phase and a gas phase, and
In the immediate vicinity of the upstream portion of the gas dispersion plate, when the inner radius of the straight body portion of the fluidized bed reactor is 1, the center of the straight body portion is the starting point at a position of 0.7 to 1.0 from the center. The concentration (C ₁ ) of the saturated aliphatic hydrocarbon in the liquid phase at the periphery of a certain trunk, and the saturated aliphatic hydrocarbon in the liquid phase at the trunk central that is less than 0.7 from the center When the inner radius of the straight body portion of the fluidized bed reactor is set to 1 in the vicinity of the upstream portion of the gas dispersion plate, the concentration of the straight body portion (C ₂ ) satisfies C ₁ > C ₂ . Starting from the center, the average gas flow velocity (V ₁ ) of the gas flow at the peripheral edge of the body that is 0.7 to 1.0 from the center, and the body center that is less than 0.7 from the center (Co) polymerization under the condition that the average gas flow velocity (V ₂ ) of the gas flow in the section satisfies V ₁ > V _2. A method for producing an olefin polymer. The fluidized bed reactor has means for changing the direction of all or part of the gas flow supplied to the gas introduction zone, and the gas supplied to the gas introduction zone contains saturated aliphatic hydrocarbons. Is contained in a gas-liquid mixed state. The method for producing an olefin polymer according to claim 1 . The fluidized bed reactor has means for imparting a circumferential momentum of the straight body portion to the gas supplied to the gas introduction zone, and
2. The method for producing an olefin polymer according to claim 1 , wherein the gas supplied to the gas introduction region contains a saturated aliphatic hydrocarbon in a gas-liquid mixed state. Claim 1, characterized in that to supply the saturated aliphatic hydrocarbon liquid phase from the supply port formed in a gas dispersion plate periphery is the position of 0.7 to 1.0 from the center of the gas distribution plate A process for producing an olefin polymer. The method for producing an olefin polymer according to any one of claims 1 to 4 , wherein (co) polymerization of at least one α-olefin selected from ethylene and an α-olefin having 3 to 20 carbon atoms is performed.

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