Catalysts

Details Catalysts Catalysts

2003-05-28

2004-11-09

Harlan, Robert D. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S161000, C526S943000, C502S152000, C502S155000, C502S167000, C544S229000, C556S053000

Reexamination Certificate

active

06815514

ABSTRACT:

This invention relates to catalysts for olefin polymerisation, in particular to catalyst compounds containing metals &eegr;-bonded by &eegr;
5
-ligands, e.g. cyclopentadienyl ligands and &eegr; or &sgr;-bonded by a bicyclic nitrogen ligand, and their use in olefin polymerisation.
In olefin polymerization, it has long been known to use as a catalyst system the combination of a metallocene procatalyst and an alumoxane or boron based co-catalyst.
By “metallocene” is here meant an &eegr;-ligand metal complex, e.g. an “open sandwich” or “half sandwich” compound in which the metal is complexed by a single &eegr;-ligand, a “sandwich” compound in which the metal is complexed by two or more &eegr;-ligands, a “handcuff” compound” in which the metal is complexed by a bridged bis-&eegr;-ligand or a “scorpionate” compound in which the metal is complexed by an &eegr;-ligand linked by a bridge to a &sgr;-ligand.
Metallocene procatalysts are generally used as part of a catalyst system which also includes an ionic cocatalyst or catalyst activator, for example, an aluminoxane (e.g. methylaluminoxane (MAO), hexaisobutylaluminoxane and tetraisobutylaluminoxane) or a boron compound (e.g. a fluoroboron compound such as triphenylpentafluoroboron or triphentylcarbenium tetraphenylpentafluoroborate ((C
6
H
5
)
3
B
+
B
−
(C
6
F
5
)
4
) )
Alumoxanes are compounds with alternating aluminium and oxygen atoms generally compounds of formula
where each R, which may be the same or different, is a C
1-10
alkyl group, and p is an integer having a value between 0 and 40). These compounds may be prepared by reaction of an aluminium alkyl with water. The production and use of alumoxanes is described in the patent literature, especially the patent applications of Texas Alkyls, Albemarle, Ethyl, Phillips, Akzo Nobel, Exxon, Idemitsu Kosan, Witco, BASF and Mitsui.
Traditionally, the most widely used alumoxane is methylalumoxane (MAO), an alumoxane compound in which the R groups are methyls. MAO however is poorly characterised and relatively expensive and efforts have been made to use alumoxanes other than MAO. Thus, for example WO98/32775 (Borealis) proposes the use of metallocene procatalysts with alumoxanes in which R is a C
2-10
alkyl group, eg hexaisobutylalumoxane (HIBAO). However, such metallocenes generally have poor catalyst activities with non-MAO alumoxanes.
Since each polymerisation catalyst gives rise to polymer products with slightly differing properties, there remains an ongoing search for new and improved olefin polymerisation catalysts.
We have now surprisingly found that a single site procatalyst system based on a &eegr;
5
-ligand, e.g. cyclopentadienyl type ligand and a &eegr; or &sgr;-bonding bicyclic nitrogen ligand may be used very effectively in polymerisation catalysis, especially in the manufacture of polyethylene or polypropylene.
Thus viewed from one aspect the invention provides a compound of formula (I) comprising
wherein
LIG represents an &eegr;
5
-ligand substituted by a group R
1
and a group (R″)
m
;
X represents a 1 to 3 atom bridge, optionally substituted, e.g. by R″ groups;
Y represents a nitrogen or phosphorus atom;
Z represents a carbon, silicon, nitrogen or phosphorus atom;
the ring denoted by A
1
is an optionally substituted, optionally saturated or unsaturated 5 to 12 membered heterocyclic ring;
the ring denoted by A
2
is an optionally substituted, unsaturated 5 to 12 membered heterocyclic ring;
R
1
represents hydrogen, R″ or a group OSiR′
3
;
each R′, which may be the same or different is a R
+
, OR
+
, SR
+
, NR
+
2
or PR
+
2
group where each R
+
is a C
1-16
hydrocarbyl group, a tri-C
1-8
hydrocarbylsilyl group or a tri-C
1-8
hydrocarbylsiloxy group, preferably R′ being a C
1-12
hydrocarbyl group, e.g. a C
1-8
alkyl or alkenyl group;
each R″, which may be the same or different is a ring substituent which does not form a &sgr;-bond to a metal &eegr;-bonded by the bicyclic ring, eg it may be hydrogen, R
+
, OR
+
, SR
+
, NR
+
2
or PR
+
2
group where each R
+
is a C
1-16
hydrocarbyl group, a tri-C
1-8
hydrocarbylsilyl group or a tri-C
1-8
hydrocarbylsiloxy group; and
m is zero or an integer between 1 and 3.
Viewed from a further aspect the invention provides an olefin polymerisation catalyst system comprising or produced by reaction of (1) a metallated compound as hereinbefore defined (from hereon called a procatalyst) and (2) a cocatalyst, e.g. an aluminium alkyl compound or boron compound, in particular an alumoxane, especially an aluminium alkyl compound comprising alkyl groups containing at least two carbon atoms.
Viewed from a still further aspect the invention provides a process for olefin polymerisation comprising polymerising an olefin in the presence of a catalyst system as hereinbefore described.
Viewed from a yet further aspect the invention provides a process for the preparation of a procatalyst, said process comprising metallating with a group 3 to 7 transition metal a compound of formula (I)
wherein LIG, X, Y, Z and rings A
1
and A
2
are as hereinbefore defined.
Viewed from a further aspect the invention provides the use of a procatalyst as hereinbefore defined in olefin polymerization, especially ethylene or propylene polymerisation or copolymerisation.
Viewed from a yet further aspect the invention provides an olefin polymer produced by a polymerisation catalysed by a procatalyst compound as hereinbefore defined.
The compounds of formula (I) as hereinbefore described may be coupled with a metal from groups 3 to 7. By group 3 (etc) metal is meant a metal in group 3 of the Periodic Table of the Elements, namely Sc, Y, etc. It is preferable if the metal coupling the compound of the invention is in the III
+
oxidation state, although metals in the II
+
and IV
+
oxidation states are also advantageous. The metal employed in the catalyst system of the invention is most preferably from groups 4, 5 or 6 of the periodic table, e.g. Cr, Mo, W, Ti, Zr, Hf, V, Nb or Ta. Most especially the metal is Cr or Ti, e.g. Cr
3+
or Ti
3+
.
Where the metal is Cr, it has surprisingly been found that the catalyst system of the invention is capable of making polypropylene as a powder.
The group 3 to 7 metal in the metallated procatalyst of the invention coordinates to the &eegr;
5
-ligand and &sgr; or &eegr; bonds to certain atoms in the bicyclic nitrogen ligand. Where the metal forms sigma bonds with the bicyclic nitrogen ligand, only atoms Z and N can coordinate to the metal. Thus, the metal may be coordinated only to atom X, only to N or to both the Z and N atoms. The Y atom is therefore not involved in coordination with the metal.
However, if an &eegr; ligand is formed between the metal and bicyclic nitrogen group then coordination to any double bond present in bicyclic nitrogen ligand is possible. Such &eegr; bonds may be &eegr;
2
or &eegr;
3
depending on the nature of the bicyclic nitrogen ligand. The metal may also be coordinated by hydrogen atoms, hydrocarbyl &sgr;-ligands (eg optionally substituted C
1-12
hydrocarbyl groups, such as C
1-12
alkyl, alkenyl or alkynyl groups optionally substituted by fluorine and/or aryl (eg phenyl) groups), by silane groups (eg Si(CH
3
)
3
), by halogen atoms (eg chlorine), by C
1-8
hydrocarbylheteroatom groups, by tri-C
1-8
hydrocarbylsilyl groups, by bridged bis-&sgr;-liganding groups, by amine (eg N(CH
3
)
2
) or imine (eg N═C or N═P groups, eg (iPr)
3
P═N) groups, or by other &sgr;-ligands known for use in metallocene (pro) catalysts.
By a &sgr;-ligand moiety is meant a group bonded to the metal at one or more places via a single atom, eg a hydrogen, halogen, silicon, carbon, oxygen, sulphur or nitrogen atom.
Examples of &sgr;-ligands include
halogenides (e.g. chloride and fluoride), hydrogen,
triC
1-12
hydrocarbyl-silyl or -siloxy(e.g. trimethylsilyl),
triC
1-6
hydrocarbylphosphimido (e.g. triisopropylphosphimido),
C
1-12
hydrocarbyl or hydrocarbyloxy (e.g. met

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