Olefin polymerization chelate catalyst and olefin...

Details Olefin polymerization chelate catalyst and olefin... Olefin polymerization chelate catalyst and olefin...

2000-02-03

2002-12-31

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S119000, C526S348000, C526S124200, C526S901000, C502S226000, C502S123000, C502S167000, C502S227000

Reexamination Certificate

active

06500906

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to chelated transition metal catalyst component in the presence of magnesium halide, a process for olefin polymerization using said catalyst component, and, more particularly, novel olefin polymerization catalyst containing transition metal compound chelated by chelate ligand which can copolymerize ethylene and &agr;-olefin and produce a polymer having a narrow molecular weight distribution and compositional distribution.
BACKGROUND OF THE INVENTION
Metallocene compounds are known to be an excellent catalyst for (co)polymerization of olefin and have been improved through the modification of cyclopentadienyl ligand to indenyl ligand, fluorenyl ligand, or bridged ligand. Also, there have been developments of supported metallocene catalytic system producing polyolefin with excellent morphology, which can be applied to slurry process or gas phase polymerization process. For example, in U.S. Pat. Nos. 5,439,995 or 5,455,316, they reported that the supported titanium metallocene or zirconium metallocene catalytic system showed excellent copolymerization and morphology properties. However, they still have some disadvantages such as synthetic difficulties, modification of existing polymerization process, and poor processibility of the produced polymer due to its narrow molecular weight distribution. Also, the activating components for metallocene catalysts such as MAO(methylaluminoxane) compounds or boron compounds are still quite expensive to be applied for polyolefin materials with general purpose.
Recently, they have been employing oxygen or heteroatom bound chelated transition metal compound as homogeneous catalysts for olefin polymerization, which are called non-metallocene catalysts or organometallic catalysts, and it attracted much attention, because these compounds are easier to synthesize than metallocene compounds and are known to show equivalent properties to metallocene compounds. Similar to the metallocene catalysts, these catalysts are anticipated to display excellent (co)polymerization ability, and there have been active investigation of oxygen or heteroatom bound chelated transition metal compounds as a catalyst component.
Japanese Laid-Open Patent sho 63-191811 disclosed the chelated catalysts for ethylene and propylene polymerization where chlorides of titanium chloride compound are replaced by TBP ligand(6-tert-butyl-4-methylphenoxy), and methylaluminoxane(MAO) is used as a cocatalyst. It was reported that polymerization of ethylene and propylene yielded polymer with excellent activity and high molecular weight(Mw=3,600,000). U.S. Pat. No. 5,134,104 reported chelate catalysts employing amine ligand substituted halide titanium compound, {(C
8
H
17
)
2
NTiCl
3
}, and the results of olefin polymerization with these catalysts. And in J. Am. Chem. Soc., 117, 3008, catalysts using oxygen bound chelated transition metal compounds which localize the coordination sphere of transition metal compounds were introduced. Also, transition metal compounds chelated with phenoxy derivative ligands were reported in Japanese Laid-Open Patent hei 6-340711 and EP 0606125A2, which produce high molecular weight polymer having narrow molecular weight distribution with MAO as cocatalyst.
However, the investigated organometallic catalyst or non-metallocene catalysts have never reported examples of copolymerization of &agr;-olefin, and they have never been used as a heterogeneous catalyst for olefin polymerization, which can control the morphology of polymer. Also, they have never reported examples of polymer having broad molecular weight distribution, which shows good processibility. On the other hand, conventional TiCl
4
based Ziegler-Natta catalyst, being heterogeneous catalyst, can produce a polymer having good morphology, good processibility, and broad molecular weight distribution. However, when low to medium density polyethylene is desired to obtain using conventional TiCl
4
based Ziegler-Natta catalyst, compositional distribution of the resulting copolymer tends to be very broad. Furthermore, high quality copolymers capable of being formed into films having excellent transparency, antiblocking property and heat sealing property are difficult to be obtained.
Therefore, the catalyst having hybrid character between conventional Ziegler-Natta catalyst and single site catalyst, which can produce the copolymer having narrow compositional distribution and good morphology and processibility, has been desired.
OBJECTIVE OF THE INVENTION
The objective of this invention is to provide the catalytic system for olefin polymerization employing chelated transition metal compound containing chelate ligand in the presence of MgCl
2
material having a spherical shape as support, which are capable of giving ethylene/&agr; olefin copolymer having narrow molecular weight distribution, narrow compositional distribution, excellent morphology, and good processibility.
SUMMARY OF THE INVENTION
According to this invention, the olefin polymerization catalytic system comprises chelated transition metal catalyst component[A], MgCl
2
support component[C], and aluminum cocatalyst component[B].
The preparation of chelated transition metal catalyst component[A] are prepared by the unique synthetic method, in which Mg[AlR′(OR)
3
]
2
reacts with chelate ligand to form Mg—Al-chelate ligand complex containing chelate ligand, and this complex reacts with metal halide compound to prepare chelated transition metal compound which is quite soluble in non-polar solvents.
Aluminum cocatalyst component[B], to activate the catalyst component[A], employs general organoaluminum compounds of formular R
3
Al or R
2
AlCl (R=hydrocarbon). And the catalytic system of this invention does not have to use expensive MAO(methyl aluminoxane) or boron compounds are cocatalyst.
MgCl
2
support component[C] is solid MgCl
2
having a spherical shape which can be prepared from the known method or MgCl
2
on the surface of silica which is available from the supplier.
The catalytic system of this invention may be used to produce ethylene copolymer from ethylene and at least one alpha-olefin having 3 or more carbon atoms in which the copolymer has narrow molecular weight distribution, narrow comonomer compositional distribution, excellent morphology, and good processibility.
These and other features, aspects, and advantages of this invention will become better understood with reference to the following description and appended claims.
DETAILED DESCRIPTION OF THE INVENTION
In this invention, the term “polymerization” used herein is intended sometimes to include not only homopolymerization but also copolymerization, and the term “polymer” used herein is intended sometimes to include not only homopolymer but also copolymer.
According to this invention, the chelated transition metal catalyst component[A] is prepared by the reaction of Mg[AlR′(OR)
3
]
2
with chelate ligand to form Mg—Al-chelate ligand complex [M-2] containing chelate ligand as described in equation (1-1)
Mg[AlR′(OR)
3
]
2
+chelate ligand→Mg—Al-chelate ligand complex[M-2]
Mg—Al-chelate ligand complex[M-2]+MX
4
→Transition metal component[A]
where R and R′ are independently alkyl or aryl group; M is Ti or Zr; X is halogen atom.
Mg[AlR′(OR)
3
]
2
can be prepared through the reaction of R′
2
Mg with Al(OR)
3
. Al(OR)
3
is simply prepared by adding ROH to AlR″
3
, where R, R′ and R″ are independently alkyl or aryl group. The reaction of AlR″
3
with ROH produces exothermic heat and liberate R″H. The exothermic heat and liberation speed of R″H can be controlled through the slow addition of ROH to AlR″
3
. The mole ratio of AlR″
3
to ROH is preferred to be 1:3. The reaction of Al(OR)
3
with R′
2
Mg produces mild heat of 5° C., and the reaction goes smoot

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