JP3629104B2 - Method for producing ethylene polymer - Google Patents

Description

【化２】

（Ｒ^１ は、メチル基、エチル基、プロピル基、ｎ−ブチル基、イソブチル基などの炭化水素基であり、好ましくは、メチル基、イソブチル基である。ｐは１から１００であり、好ましくは４以上、特に好ましくは８以上である。）
【００１１】
この種の化合物の製法は公知であり、例えば結晶水を有する塩類（硫酸銅水和物、硫酸アルミニウム水和物等）のペンタン、ヘキサン、ヘプタン、シクロヘキサン、デカン、ベンゼン、トルエン等の不活性炭化水素溶媒の懸濁液に、トリアルキルアルミニウムを添加して得る方法や、炭化水素溶媒中でトリアルキルアルミニウムに、固体、液体あるいは気体状の水を作用させる方法を例示することができる。
【００１２】
また、一般式（３）または（４）で示されるアルモキサンを用いてもよい。
【化３】

【化４】

（Ｒ^２ は、メチル基、エチル基、プロピル基、ｎ−ブチル基、イソブチル基などの炭化水素基であり、好ましくは、メチル基、イソブチル基である。また、Ｒ^３ はメチル基、エチル基、プロピル基、ｎ−ブチル基、イソブチル基などの炭化水素基、あるいは塩素、臭素等のハロゲンあるいは水素、水酸基から選ばれ、Ｒ^２ とは異なった基を示す。また、Ｒ^３ は同一でも異なってもよい。ｑは通常１から１００であり、好ましくは３以上であり、ｑ＋ｒは２から１００、好ましくは６以上である。）
【００１３】
一般式（３）あるいは（４）で、
［Ｏ−Ａｌ（Ｒ^２ ）］_ｑ ユニットと、［Ｏ−Ａｌ（Ｒ^３ ）］_ｒ ユニットはブロック的に結合したものであっても、規則的あるいは不規則的にランダムに結合したものであっても良い。
このようなアルモキサン化合物の製法は、前述した一般式のアルモキサンと同様であり、１種類のトリアルキルアルミニウムの代わりに、２種以上のトリアルキルアルミニウムを用いるか、１種類以上のトリアルキルアルミニウムと１種類以上のジアルキルアルミニウムモノハライドあるいはジアルキルアルミニウムモノハイドライドなどを用いれば良い。
【００１４】
本発明方法において使用する触媒は、ハロゲン化クロム化合物、シクロアルカジエニル塩、無機酸化物固体及びアルモキサンを化学的に反応させて製造する。すなわち、ハロゲン化クロム化合物と無機酸化物固体をエーテル溶媒に懸濁させた後、これをシクロアルカジエニル塩で処理し、得られる固体成分をアルモキサンで処理して製造することができる。
ハロゲン化クロム化合物を無機酸化物固体を懸濁させるのに用いるエーテル溶媒としては、ジエチルエーテル、ジイソプロピルエーテル、ジオキサン、１，２−ジメトキシエタン、テトラヒドロフランなどの脂肪族または脂環式エーテルが挙げられ、なかでもテトラヒドロフランが好ましい。無機酸化物固体に対するハロゲン化クロム化合物の添加量は、クロム原子が無機酸化物固体に対して、０．０１〜１０ｗｔ％、好ましくは０．１〜５ｗｔ％となるような量を添加する。
この懸濁液にシクロアルカジエニル塩を添加して反応を行わせるが、クロム塩中のクロム原子とシクロアルカジエニル塩のモル比は１：１〜１：１０、好ましくは１：１〜１：５で行う。反応温度は−７８℃〜溶媒の沸点、好ましくは−２０℃〜５０℃、また反応時間は１０分〜２４時間、好ましくは３０分〜５時間である。この反応によりクロム原子が無機酸化物固体に担持される。反応後、溶媒を真空下で除去する方法、または濾過によって分離する方法によって流動性の良い固体成分が得られる。
【００１５】
上記固体成分をアルモキサンで処理するにあたっては、ペンタン、ヘキサン、ヘプタン、シクロヘキサン、ベンゼン、トルエンなどのような不活性炭化水素中で行う。固体成分中のクロム原子に対して、処理に用いるアルモキサン中のアルミニウム原子が、アルミニウム／クロムモル比＝１〜１０００、好ましくは５〜１００となるような量で処理を行うのが好ましい。反応温度は−７８℃〜溶媒の沸点、好ましくは−２０℃〜５０℃、また反応時間は１０分〜２４時間、好ましくは３０分〜５時間である。処理後、溶媒を真空下で除去する方法、または濾過によって分離する方法によって流動性の良い触媒が得られる。
【００１６】
上記触媒を使用して本発明方法を実施するにあたり、エチレンの重合方法としてはスラリー重合、溶液重合のような液相重合法あるいは気相重合法などが可能である。液相重合法は通常炭化水素溶媒中で実施されるが、炭化水素溶媒としてはブタン、イソブタン、ヘキサン、シクロヘキサン、ベンゼン、トルエン、キシレンなどの不活性炭化水素の単独または混合物が用いられる。重合温度は一般には０〜３００℃であり、実用的には２０〜２００℃である。また、分子量調節のために重合系内に水素などを共存させることができる。さらに、必要に応じてプロピレン、１−ブテン、１−ヘキセン、４−メチル−１−ペンテン、１−オクテンなどのα−オレフィンを単独または２種以上重合器に導入して共重合させることもできる。
【００１７】
以下に実施例および比較例を挙げて、本発明をさらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
なお、実施例および比較例において、メルトフローレート（以下「ＭＦＲ」という）はＪＩＳ Ｋ−７２１０、表１の試験条件４に従い、温度１９０℃および荷重２．１６ｋｇｆの条件で測定した。ハイロードメルトフローレート（以下「ＨＬＭＦＲ」をいう）はＪＩＳ Ｋ−７２１０表１、試験条件７に従い、温度１９０℃および荷重２１．６ｋｇｆの条件で測定した。
ＨＬＭＦＲをＭＦＲで除した値、すなわちＨＬＭＦＲ／ＭＦＲの値が大きいほど、分子量分布が広いことを示す。
溶融張力は、東洋精機（株）製のメルトテンションテスターを用い、樹脂温度１９０℃、オリフィス径２．０９５ｍｍ、オリフィス長さ８ｍｍ、押出し速度１５ｍｍ／ｍｉｎ、巻き取り速度６．５ｍｍ／ｍｉｎの条件で測定した。
ダイスウェルレシオ（以下「ＳＲ」という）は、ＨＬＦＲと同じ装置を用い、ＨＬＭＦＲ測定時の押し出し物の外径のオリフィス系に対する膨張度（％）で示した。
なお、これらの測定に用いたサンプルは予め東洋精機（株）製プラストグラフを用いて、添加剤としてチバガイキー社製Ｂ２２５を０．２ｗｔ％加えた後、窒素雰囲気下、１９０℃、７分間混練した。
【００１８】
【実施例】
（実施例１）
（１）触媒調製
６００℃で４時間焼成したＤＡＶＩＳＯＮ９５２グレードのシリカ３．０ｇにテトラヒドロフラン３５ｍｌを加えスラリーとした。このスラリーにＡｌｄｒｉｃｈ社製ＣｒＣｌ_３ ・３ＴＨＦ錯体４５．０ｍｇ（０．１２ｍｍｏｌ；クロム原子担持量として０．２ｗｔ％）添加をした。４０℃に加温後、Ａｌｄｒｉｃｈ社製２．０ｍｏｌ／１ シクロペンタジエニルナトリウムのテトラヒドロフラン溶液０．１８ｍｌ（０．３６ｍｍｏｌ）を添加した。４０℃で１時間撹拌後、真空下で溶媒を完全に除去して固体成分を得た。得られた固体成分にトルエン３５ｍｌを加えスラリーとした。このスラリーに東−・アクゾ社製メチルアルモキサンの２．０ｍｏｌ／１ トルエン溶液０．６ｍｌ（１．２ｍｍｏｌ）を添加し、４０℃で２時間撹拌した。真空下で溶媒を除去し、触媒を得た。
（２）エチレン重合
充分に窒素置換した１．５Ｌのオートクレーブにイソブタン０．６Ｌ、上記で得られた触媒２００ｍｇを仕込み、内温を１００℃まで昇温した。ついで水素をゲージ圧で０．５Ｋｇ／ｃｍ^２ 加え、さらにエチレンを圧入し、エチレン分圧を１４Ｋｇ／ｃｍ^２ となるように保ちながら、１時間重合を行った。ついで内容ガスを系外に放出することにより、重合を終結した。その結果、６２ｇのポリエチレンが得られた。重合活性は３１０ｇポリマー／ｇ触媒／時間であった。このポリマーのＭＦＲ＝０．１１、ＨＬＭＦＲ＝６．４、ＨＬＭＦＲ／ＭＦＲ＝５８．２であり、分子量分布は広いものであった。また、溶融張力は３０．２ｇ、ＳＲは８７％であった。
【００１９】
（実施例２）
実施例１（１）の触媒調製において、添加するメチルアルモキサンの量を１．２ｍｌ（２．４ｍｍｏｌ）とした以外は、全て実施例１と同様に触媒を調製して重合を行った。結果は表１に示す。
（実施例３）
実施例１（１）の触媒調製において、シクロペンタジエニルナトリウムの代わりにＡｌｄｒｉｃｈ社製ペンタメチルシクロペンタジエニルナトリウムの０．５ｍｏｌ／１ テトラヒドロフラン溶液を０．７２ｍｌ（０．３６ｍｍｏｌ）添加した以外は、全て実施例１と同様に触媒を調製して重合を行った。結果は表１に示す。
（実施例４）
実施例１（１）の触媒調製において、シクロペンタジエニルナトリウムの代わりに、「実験化学講座（第４版）」１８巻、２７頁（丸善）に従ってインデンとブチルリチウムから合成したインデニルリチウムの１．０ｍｏｌ／１ テトラヒドロフラン溶液を０．３６ｍｌ（０．３６ｍｍｏｌ）添加した以外は、全て実施例１と同様に触媒を調製して重合を行った。結果は表１に示す。
（実施例５）
実施例１（１）の触媒調製において、シクロペンタジエニルナトリウムの代わりに、「実験化学講座（第４版）」１８巻、２７頁（丸善）に従ってフルオレンとブチルリチウムから合成したフルオレニルリチウムの１．０ｍｏｌ／１ テトラヒドロフラン溶液を０．３６ｍｌ（０．３６ｍｍｏｌ）添加した以外は、全て実施例１と同様に触媒を調製して重合を行った。結果は表１に示す。
【００２０】
（比較例１）
（１）触媒調製
６００℃で４時間焼成したＤＡＢＩＳＯＮ９５２グレードのシリカ３．０ｇにトルエン５０ｍｌを加えスラリーとした。これに「新実験化学講座」１２巻、１１０頁（丸善）に従って三塩化クロムとシクロペンタジエニルナトリウムから合成したビス（シクロペンタジエニル）クロム２１ｍｇ（０．１２ｍｍｏｌ；クロム原子担持量として０．２ｗｔ％）を添加し、４０℃で１時間撹拌した。このスラリーに東ソー・アクゾ社製メチルアルモキサンの２．０ｍｏｌ／ｌ トルエン溶液０．６ｍｌ（１．２ｍｍｏｌ）を添加し、４０℃で２時間撹拌した。真空下で溶媒を除去し、触媒を得た。
（２）エチレン重合
（１）で得られたビス（シクロペンタジエニル）クロム担持触媒を用いて、全て実施例１と同様に重合を行った。結果は表１に示す。分子量分布が実施例１〜５の場合よりも狭く、さらに溶融張力、ＳＲともに低かった。
【００２１】
（比較例２）
（１）触媒調製
６００℃で４時間焼成したＤＡＶＩＳＯＮ９５２グレードのシリカ３．０ｇにトルエン５０ｍｌを加えスラリーとした。これにＫａｒｏｌら（Ｊｏｕｒｎａｌｏｆ Ｐｏｌｙｍｅｒ Ｓｃｉｅｎｃｅ：Ｐｏｌｙｍｅｒ ＣｈｅｍｉｓｔｒｙＥｄｉｔｉｏｎ，１６，７７１（１９７８））の方法によって三塩化クロムとインデニルナトリウムから合成したビス（インデニル）クロム３２．５ｍｇ（０．１２ｍｍｏｌ；クロム原子担持量として０．２ｗｔ％）を添加し、４０℃で１時間撹拌した。このスラリーに東ソー・アクゾ社製メチルアルモキサンの２．０ｍｏｌ／ｌ トルエン溶液０．６ｍｌ（１．２ｍｍｏｌ）を添加し、４０℃で２時間撹拌した。真空下で溶媒を除去し、触媒を得た。
（２）エチレン重合
（１）で得られたビス（インデニル）クロム担持触媒を用いて、全て実施例１と同様に重合を行った。結果は表１に示す。分子量分布が実施例１〜５の場合よりも狭く、さらに溶融張力、ＳＲともに低かった。
【００２２】
（比較例３）
（１）触媒調製
６００℃で４時間焼成したＤＡＶＩＳＯＮ９５２グレードのシリカ３．０ｇにトルエン５０ｍｌを加えスラリーとした。これにＫａｒｏｌら（Ｊｏｕｒｎａｌｏｆ Ｐｏｌｙｍｅｒ Ｓｃｉｅｎｃｅ：Ｐｏｌｙｍｅｒ Ｃｈｅｍｉｓｔｒｙ Ｅｄｉｔｉｏｎ，１６，７７１（１９７８））の方法によって三塩化クロムとフルオレニルナトリウムから合成したビス（フルオレニル）クロムのトルエン溶液を、ビス（フルオレニル）クロムが４４．１ｍｇ（０．１２ｍｍｏｌ：クロム原子担持量として０．２ｗｔ％）導入されるような量だけ添加し、４０℃で１時間撹拌した。このスラリーに東ゾー・アクゾ社製メチルアルモキサンの２．０ｍｏｌ／ｌ トルエン溶液０．６ｍｌ（１．２ｍｍｏｌ）を添加し、４０℃で２時間撹拌した。真空下で溶媒を除去し、触媒を得た。
（２）エチレン重合
（１）で得られたビス（フルオレニル）クロム担持触媒を用いて、全て実施例１と同様に重合を行った。結果は表１に示す。分子量分布は広いが、溶融張力、ＳＲがともに低かった。
【００２３】
【表１】

【００２４】
【発明の効果】
本発明は、合成が面倒であり、不安定なシクロアルカジエニルクロム錯体を、ハロゲン化クロムとシクロアルカジエニル塩とからこれを触媒調製系内で生成させ、同時に無機酸化物に担持させてしまうことにより、錯体を合成・単離して触媒を調製する場合に比べ、広い分子量分布を有し、しかも溶融張力が高く、ダイスウェルの大きいエチレン系重合体を効率よく製造することに成功した。そのため本発明方法により得られるエチレン系重合体は、インフレーションフィルム成形やブロー成形に好適な高品質のエチレン系重合体である。
【図面の簡単な説明】
図１は本発明の製造方法における触媒調製のフローチャート図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an ethylene polymer. More specifically, the present invention relates to a method for producing an ethylene-based polymer having a wide molecular weight distribution and a large melt tension and large die swell, which is suitable for blown film forming and blown film forming using a chromium-based catalyst.
[0002]
[Prior art]
Conventionally, methods for producing an ethylene polymer using a catalyst in which an organic chromium compound having a cycloalkadienyl group is supported on an inorganic oxide solid have already been disclosed in Japanese Patent Publication Nos. 45-40902 and 55-8086. It has been proposed in, for example, Kaihei 3-93804, JP-A-3-93805, JP-A-3-93809, and JP-A-6-145233.
That is, in Japanese Patent Publication No. 45-40902, bis (cyclopentadienyl) chromium is used, and in Japanese Patent Publication No. 55-8086, bis (indenyl) chromium or bis (fluorenyl) chromium is supported on an inorganic oxide solid. Is used to produce an ethylene polymer.
However, ethylene polymers obtained with these catalysts are not suitable for blown film molding and blow molding because of their narrow molecular weight distribution and low melt tension and die swell. In the inventions such as JP-A-3-93804, JP-A-3-93805, JP-A-3-93809, and JP-A-6-145233, the synthesized and isolated substituted cyclopentadienyl ligands are used. A catalyst in which an organic chromium compound is supported on an inorganic oxide solid is used. Ethylene polymers produced using these catalysts have a wide molecular weight distribution, but the organic chromium compounds used are not only insensitive to oxygen and moisture in the air and easily deteriorated, but also inconvenient to handle, These organic chromium compounds have a drawback that the synthesis process is very complicated.
[0003]
Recently, in JP 7-503739, a molecular weight distribution was obtained by changing the molar ratio of alumoxane to chromium during polymerization using a catalyst composed of an organic chromium compound having a cycloalkadienyl group, an inorganic oxide solid and an alumoxane. A method for producing an ethylene polymer for controlling the above has been disclosed. According to this method, an ethylene polymer having a wide molecular weight distribution can be obtained. However, the production process is extremely complicated and difficult to operate, so that it is not practical.
Therefore, a chromium-based catalyst having a cycloalkadienyl group supported on an inorganic oxide solid, suitable for inflation film molding and blow molding using a catalyst obtained by a simple process, has a wide molecular weight distribution, Development of a method for producing an ethylene polymer having a high melt tension and die swell has been desired.
[0004]
[Problems to be solved by the invention]
The present invention is an ethylene polymer having a wide molecular weight distribution, a large melt tension and a large die swell, which is suitable for inflation film molding and blow molding, with a simple preparation, handling and ethylene polymer synthesis process of the above catalyst. The purpose is to develop a method for efficiently producing the sucrose.
[0005]
[Means for Solving the Problems]
As a result of intensive studies in view of the above problems, the present inventors have
(1) A method for producing an ethylene polymer using a catalyst obtained by suspending a chromium halide compound and an inorganic oxide solid in an ether solvent and then treating a solid component treated with a cycloalkadienyl salt with an alumoxane; (2) The above object has been achieved by developing the method for producing an ethylene polymer according to (1), wherein the halogenated chromium compound is chromium chloride or a chromium chloride complex.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described below.
The chromium halide compound used in the present invention includes chromium dichloride, chromium trichloride, chromium difluoride, chromium trifluoride, chromium dibromide, chromium tribromide, chromium diiodide, chromium triiodide. And the like. Among them, chromium dichloride or chromium trichloride is preferable. Further, a chromium trichloride tetrahydrofuran complex (CrCl ₃ · 3THF) or a chromium dichloride tetrahydrofuran complex (CrCl ₂ · 2THF) is also preferably used.
[0007]
Cycloalkadienyl salts include cyclopentadienyl lithium, cyclopentadienyl sodium, cyclopentadienyl potassium, methylcyclopentadienyl lithium, methylcyclopentadienyl sodium, methylcyclopentadienyl potassium, pentamethylcyclo Pentadienyl lithium, pentamethylcyclopentadienyl sodium, pentamethylcyclopentadienyl potassium, indenyl lithium, indenyl sodium, indenyl potassium, fluorenyl lithium, fluorenyl sodium, fluorenyl potassium, 9- Examples include methyl fluorenyl lithium, 9-methyl fluorenyl sodium, and 9-methyl fluorenyl potassium. These cycloalkadienyl salts can be obtained by reacting the corresponding cycloalkadiene with lithium, sodium or potassium in an ether solvent by a known method.
[0008]
The inorganic oxide solid is a metal oxide of Group 2, Group 4, Group 13 or Group 14 of the Periodic Table. Specifically, magnesia, titania, zirconia, silica, alumina, silica-alumina, silica -Titania, silica-zirconia, aluminum phosphate or mixtures thereof. These inorganic oxide solid specific surface area 50~1000m ² / g, preferably 200~800m ² / g, a pore volume of 0.5~3.0cm ³ / g, preferably 1.0~2.5cm ³ / g and an average particle diameter of 10 to 200 μm, preferably 50 to 150 μm are preferably used. It is desirable that the inorganic oxide solid is previously baked to remove adsorbed moisture before being used. The firing of the inorganic oxide solid is usually carried out by arbitrarily selecting from a temperature range of 100 to 900 ° C. and a range of 30 minutes to 24 hours in a nitrogen gas stream dried by circulating a molecular sieve layer. It is preferable to dry under a solid fluidized state with a sufficient amount of nitrogen gas.
[0009]
Alumoxane is a well-known compound in the art, but its preparation and structure are described in Polyhedron, 9, 429-453 (1990), Ziegler Catalysts, G .; Fink et al. (Eds.) 57-82, Springer-Verlag (1995) and the like. Examples of the alumoxane used in the present invention include compounds represented by the following general formula (1) or (2).
[0010]
[Chemical 1]

[Chemical 2]

(R ¹ is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group, an n-butyl group or an isobutyl group, preferably a methyl group or an isobutyl group. P is 1 to 100, preferably 4 or more, particularly preferably 8 or more.)
[0011]
Methods for producing this type of compound are known, for example, inert carbonization of salts having crystal water (such as copper sulfate hydrate and aluminum sulfate hydrate) such as pentane, hexane, heptane, cyclohexane, decane, benzene, and toluene. Examples thereof include a method obtained by adding a trialkylaluminum to a suspension of a hydrogen solvent, and a method in which solid, liquid or gaseous water is allowed to act on a trialkylaluminum in a hydrocarbon solvent.
[0012]
Moreover, you may use the alumoxane shown by General formula (3) or (4).
[Chemical 3]

[Formula 4]

(R ² is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group, an n-butyl group or an isobutyl group, preferably a methyl group or an isobutyl group. Also, R ³ is a methyl group or an ethyl group. And a hydrocarbon group such as propyl group, n-butyl group and isobutyl group, or a halogen or hydrogen such as chlorine and bromine, a hydroxyl group, and a group different from R ^2, and R ³ is the same or different. Q is usually 1 to 100, preferably 3 or more, and q + r is 2 to 100, preferably 6 or more.)
[0013]
In general formula (3) or (4),
The [O—Al (R ² )] _q unit and the [O—Al (R ³ )] _r unit may be linked in a regular or irregular manner at random, even though they are linked in a block manner. May be.
The manufacturing method of such an alumoxane compound is the same as that of the alumoxane of the general formula described above, and two or more types of trialkylaluminum are used instead of one type of trialkylaluminum, or one or more types of trialkylaluminum and 1 More than one kind of dialkylaluminum monohalide or dialkylaluminum monohydride may be used.
[0014]
The catalyst used in the method of the present invention is produced by chemically reacting a chromium halide compound, a cycloalkadienyl salt, an inorganic oxide solid, and an alumoxane. That is, it can be produced by suspending a chromium halide compound and an inorganic oxide solid in an ether solvent, treating the suspension with a cycloalkadienyl salt, and treating the resulting solid component with an alumoxane.
Examples of the ether solvent used for suspending the inorganic oxide solid with the chromium halide compound include aliphatic or alicyclic ethers such as diethyl ether, diisopropyl ether, dioxane, 1,2-dimethoxyethane, and tetrahydrofuran, Of these, tetrahydrofuran is preferred. The amount of the chromium halide compound added to the inorganic oxide solid is such that the chromium atom is 0.01 to 10 wt%, preferably 0.1 to 5 wt%, relative to the inorganic oxide solid.
A cycloalkadienyl salt is added to this suspension to cause the reaction, and the molar ratio of the chromium atom in the chromium salt to the cycloalkadienyl salt is 1: 1 to 1:10, preferably 1: 1 to 1. 1: 5. The reaction temperature is -78 ° C to the boiling point of the solvent, preferably -20 ° C to 50 ° C, and the reaction time is 10 minutes to 24 hours, preferably 30 minutes to 5 hours. By this reaction, chromium atoms are supported on the inorganic oxide solid. After the reaction, a solid component having good fluidity can be obtained by removing the solvent under vacuum or separating by filtration.
[0015]
The solid component is treated with alumoxane in an inert hydrocarbon such as pentane, hexane, heptane, cyclohexane, benzene, toluene and the like. It is preferable to treat the chromium atom in the solid component in such an amount that the aluminum atom in the alumoxane used for the treatment has an aluminum / chromium molar ratio = 1 to 1000, preferably 5 to 100. The reaction temperature is -78 ° C to the boiling point of the solvent, preferably -20 ° C to 50 ° C, and the reaction time is 10 minutes to 24 hours, preferably 30 minutes to 5 hours. After the treatment, a catalyst having good fluidity can be obtained by removing the solvent under vacuum or separating by filtration.
[0016]
In carrying out the method of the present invention using the above catalyst, the polymerization method of ethylene can be a liquid phase polymerization method such as slurry polymerization or solution polymerization, or a gas phase polymerization method. The liquid phase polymerization method is usually carried out in a hydrocarbon solvent, and as the hydrocarbon solvent, an inert hydrocarbon such as butane, isobutane, hexane, cyclohexane, benzene, toluene, xylene or the like is used alone or as a mixture. The polymerization temperature is generally 0 to 300 ° C. and practically 20 to 200 ° C. In addition, hydrogen or the like can coexist in the polymerization system for molecular weight adjustment. Furthermore, if necessary, α-olefins such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like can be copolymerized by introducing them alone or in two or more kinds into a polymerization vessel. .
[0017]
EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.
In Examples and Comparative Examples, the melt flow rate (hereinafter referred to as “MFR”) was measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kgf according to JIS K-7210, test condition 4 in Table 1. The high load melt flow rate (hereinafter referred to as “HLMFR”) was measured under conditions of a temperature of 190 ° C. and a load of 21.6 kgf in accordance with JIS K-7210 Table 1, test condition 7.
The larger the value obtained by dividing HLMFR by MFR, that is, the value of HLMFR / MFR, the wider the molecular weight distribution.
Melt tension was measured using a melt tension tester manufactured by Toyo Seiki Co., Ltd. under conditions of a resin temperature of 190 ° C., an orifice diameter of 2.095 mm, an orifice length of 8 mm, an extrusion speed of 15 mm / min, and a winding speed of 6.5 mm / min. It was measured.
The die swell ratio (hereinafter referred to as “SR”) was expressed in terms of the degree of expansion (%) with respect to the orifice system of the outer diameter of the extrudate at the time of HLMFR measurement using the same apparatus as HLFR.
In addition, the sample used for these measurements was previously kneaded for 7 minutes at 190 ° C. in a nitrogen atmosphere after adding 0.2 wt% B225 manufactured by Ciba-Gaykey as an additive using a plastograph manufactured by Toyo Seiki Co., Ltd. .
[0018]
【Example】
Example 1
(1) Preparation of catalyst 35 ml of tetrahydrofuran was added to 3.0 g of DAVISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. To this slurry was added 45.0 mg (0.12 mmol; 0.2 wt% as the amount of chromium atom supported) of CrCl ₃ • 3THF complex manufactured by Aldrich. After heating to 40 ° C., 0.18 ml (0.36 mmol) of a 2.0 mol / 1 cyclopentadienyl sodium tetrahydrofuran solution manufactured by Aldrich was added. After stirring at 40 ° C. for 1 hour, the solvent was completely removed under vacuum to obtain a solid component. To the obtained solid component, 35 ml of toluene was added to form a slurry. To this slurry, 0.6 ml (1.2 mmol) of a 2.0 mol / 1 toluene solution of methylalumoxane manufactured by Toago Akzo Co. was added and stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst.
(2) Ethylene polymerization A 1.5 L autoclave sufficiently purged with nitrogen was charged with 0.6 L of isobutane and 200 mg of the catalyst obtained above, and the internal temperature was raised to 100 ° C. Subsequently, hydrogen was added at a gauge pressure of 0.5 Kg / cm ² , and ethylene was further injected to carry out polymerization for 1 hour while maintaining the ethylene partial pressure at 14 Kg / cm ² . Subsequently, the content gas was discharged out of the system to terminate the polymerization. As a result, 62 g of polyethylene was obtained. The polymerization activity was 310 g polymer / g catalyst / hour. The polymer had MFR = 0.11, HLMFR = 6.4, and HLMFR / MFR = 58.2, and the molecular weight distribution was wide. The melt tension was 30.2 g and SR was 87%.
[0019]
(Example 2)
In the catalyst preparation of Example 1 (1), a catalyst was prepared and polymerized in the same manner as in Example 1 except that the amount of methylalumoxane added was 1.2 ml (2.4 mmol). The results are shown in Table 1.
(Example 3)
In the catalyst preparation of Example 1 (1), instead of cyclopentadienyl sodium, 0.72 ml (0.36 mmol) of 0.5 mol / 1 tetrahydrofuran solution of pentamethylcyclopentadienyl sodium made by Aldrich was added. All were prepared and polymerized in the same manner as in Example 1. The results are shown in Table 1.
Example 4
In the preparation of the catalyst of Example 1 (1), instead of cyclopentadienyl sodium, indenyl lithium synthesized from indene and butyl lithium according to “Experimental Chemistry Course (4th edition)” Vol. 18, page 27 (Maruzen) A catalyst was prepared and polymerized in the same manner as in Example 1 except that 0.36 ml (0.36 mmol) of a 1.0 mol / 1 tetrahydrofuran solution was added. The results are shown in Table 1.
(Example 5)
Fluorenyllithium synthesized from fluorene and butyllithium according to “Experimental Chemistry Course (4th edition)” Vol. 18, page 27 (Maruzen) instead of cyclopentadienyl sodium in the catalyst preparation of Example 1 (1) A catalyst was prepared and polymerized in the same manner as in Example 1 except that 0.36 ml (0.36 mmol) of a 1.0 mol / 1 tetrahydrofuran solution was added. The results are shown in Table 1.
[0020]
(Comparative Example 1)
(1) Preparation of catalyst 50 ml of toluene was added to 3.0 g of DABSON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. To this, 21 mg (0.12 mmol; bis (cyclopentadienyl) chromium synthesized from chromium trichloride and cyclopentadienyl sodium according to “New Experimental Chemistry Course”, Vol. 12, p. 2 wt%) was added and stirred at 40 ° C. for 1 hour. To this slurry, 0.6 ml (1.2 mmol) of a 2.0 mol / l toluene solution of methylalumoxane manufactured by Tosoh Akzo Corporation was added and stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst.
(2) Ethylene Polymerization Polymerization was conducted in the same manner as in Example 1 using the bis (cyclopentadienyl) chromium supported catalyst obtained in (1). The results are shown in Table 1. The molecular weight distribution was narrower than those in Examples 1 to 5, and both the melt tension and SR were low.
[0021]
(Comparative Example 2)
(1) Preparation of catalyst 50 ml of toluene was added to 3.0 g of DAVISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. Further, 32.5 mg (0.12 mmol; bis (indenyl) chromium bis (indenyl) chromium synthesized from chromium trichloride and indenyl sodium by the method of Karol et al. (Journalof Polymer Science: Polymer Chemistry Edition, 16, 771 (1978)). 0.2 wt%) was added and stirred at 40 ° C. for 1 hour. To this slurry, 0.6 ml (1.2 mmol) of a 2.0 mol / l toluene solution of methylalumoxane manufactured by Tosoh Akzo Corporation was added and stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst.
(2) Ethylene Polymerization Polymerization was conducted in the same manner as in Example 1 using the bis (indenyl) chromium supported catalyst obtained in (1). The results are shown in Table 1. The molecular weight distribution was narrower than those in Examples 1 to 5, and both the melt tension and SR were low.
[0022]
(Comparative Example 3)
(1) Preparation of catalyst 50 ml of toluene was added to 3.0 g of DAVISON 952 grade silica calcined at 600 ° C. for 4 hours to form a slurry. To this, a toluene solution of bis (fluorenyl) chromium synthesized from chromium trichloride and fluorenyl sodium by the method of Karol et al. (Journalof Polymer Science: Polymer Chemistry Edition, 16, 771 (1978)) 44.1 mg (0.12 mmol: 0.2 wt% as the amount of chromium atom supported) was added, and the mixture was stirred at 40 ° C. for 1 hour. To this slurry, 0.6 ml (1.2 mmol) of a 2.0 mol / l toluene solution of methylalumoxane manufactured by Tozo Akzo Co. was added and stirred at 40 ° C. for 2 hours. The solvent was removed under vacuum to obtain the catalyst.
(2) Ethylene Polymerization Polymerization was conducted in the same manner as in Example 1 using the bis (fluorenyl) chromium supported catalyst obtained in (1). The results are shown in Table 1. Although the molecular weight distribution was wide, both melt tension and SR were low.
[0023]
[Table 1]

[0024]
【The invention's effect】
In the present invention, the synthesis is troublesome and an unstable cycloalkadienyl chromium complex is produced from a chromium halide and a cycloalkadienyl salt in a catalyst preparation system, and simultaneously supported on an inorganic oxide. As a result, the present inventors succeeded in efficiently producing an ethylene polymer having a broad molecular weight distribution, a high melt tension, and a large die swell as compared with the case of preparing a catalyst by synthesizing and isolating a complex. Therefore, the ethylene polymer obtained by the method of the present invention is a high-quality ethylene polymer suitable for blown film molding and blow molding.
[Brief description of the drawings]
FIG. 1 is a flowchart of catalyst preparation in the production method of the present invention.

Claims (2)

Production of an ethylene polymer characterized by using a catalyst obtained by suspending a chromium halide compound and an inorganic oxide solid in an ether solvent and then treating the solid component treated with a cycloalkadienyl salt with an alumoxane Method. 2. The method for producing an ethylene polymer according to claim 1, wherein the chromium halide compound is chromium chloride or a chromium chloride complex.

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