Process for the preparation of ethylene polymers

Details Process for the preparation of ethylene polymers Process for the preparation of ethylene polymers

2001-08-28

2004-09-07

Lu, Caixia (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S160000, C526S165000, C526S127000, C526S352000, C526S943000, C502S132000, C502S155000

Reexamination Certificate

active

06787619

ABSTRACT:

PROCESS FOR THE PREPARATION OF ETHYLENE POLYMERS
The present invention relates to a polymerization process for the preparation of ethylene polymers in the presence of a metallocene catalyst. The invention also relates to a process for the preparation of the relevant metallocenes and of the corresponding ligands, which are useful as intermediates in the synthesis of said metallocene compounds. The invention further relates to ethylene copolymers obtainable with those metallocene catalysts.
Metallocene compounds having two bridged cyclopentadienyl or indenyl groups are known as catalyst components for the home and copolymerization reaction of ethylene.
Also known are metallocene compounds containing a bridged bis-fluorenyl ligand system for use in the polymerization of olefins.
For instance, in EP-A-0 632 066 it is discloses the use of bis-fluorenyl based metallocenes for the production of elastomeric copolymers of ethylene with propylene.
More recently, heterocyclic metallocene compounds used in the polymerization of alpha-olefins have been disclosed.
For example, PCT application WO 98/22486 discloses metallocenes containing a cyclopentadienyl radical directly coordinating the central metal atom, to which are fused one or more rings containing at least one heteroatom. These metallocenes, in combination with a suitable cocatalyst, are used in the polymerization of olefins such as ethylene. However, the molecular weight that can be obtained is still not sufficient for many uses and the activity of the catalyst systems containing said metallocenes, when used in the polymerization of ethylene, is not satisfactory.
It would be desirable to identify metallocene catalysts capable of yielding ethylene polymers having a high molecular weight and which also have high activities, such that the amount of the catalyst remaining in the polymer is minimized. Further, it would be advantageous to obtain copolymers of ethylene with alpha-olefins and polyenes in which the comonomer units in the polymeric chain are homogeneously distributed.
It has been found unexpectedly that it is possible to achieve the above and other results by carrying out the polymerization reaction of ethylene in the presence of a catalyst based on a class of heteroatom containing metallocene compounds.
Thus, according to a first aspect of the present invention a process is provided for the preparation ethylene polymers, comprising the polymerization reaction of ethylene and optionally one or more olefins in the presence of a catalyst comprising the product obtainable by contacting:
(A) a metallocene compound of the general formula (1):
SiR
1
R
2
LQMXp  (I)
wherein SiR
1
R
2
is a divalent group bridging the moieties L and Q;
R
1
and R
2
, which may be the same or different, are selected from hydrogen, a C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radical optionally containing heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements; optionally R
1
and R
2
form a ring comprising from 3 to 8 atoms, which can bear substituents;
Q is a moiety of formula (II):
wherein A and B are selected from sulfur (S), oxygen (O) and CR
5
, R
5
is selected from hydrogen, a C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radicals optionally containing heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements; and wherein the rings containing A and B have a double bond in the allowed position having an aromatic character, either A or B being different from CR
5
i.e. if A is S or O, B is CR
5
or if B is S or O, A is CR
5
;
R
3
and R
4
, which may be the same or different , are selected from hydrogen a C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radical optionally containing heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements; preferably R
3
and R
4
, which may be the same or different, are selected from a C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radical optionally containing heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements; L is a moiety of formula (III):
wherein R
6
, R
7
, R
8
and R
9
, which may be the same or different, are selected from C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radicals optionally containing heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements; and two adjacent R
6
and R
7
and/or R
8
and R
9
can form a ring comprising from 3 to 8 atoms, which can include heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements and can bear substituents;
M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements (new IUPAC version), X, which may be the same or different, is a ligand selected from hydrogen, halogen, R
10
, OR
10
, OSO
2
CF
3
, OCOR
10
, SR
10
, NR
10
2
or PR
10
2
group, wherein R
10
is selected from hydrogen, a C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radical, optionally containing heteroatoms belonging to groups 13 or 15-17 of the Periodic Table of the Elements;
p is an integer of from 0 to 3, preferably from 1 to 3 being equal to the oxidation state of the metal M minus 2 and
(B) an alumoxane and/or a compound capable of forming an alkyl metallocene cation. The transition metal M is preferably selected from titanium, zirconium and hafnium preferably in the formal oxidation state of +4. Most preferably zirconium is used. Preferably p is 2.
The X substituents are preferably chloride or methyl groups.
Preferably the substituents R
1
and R
2
are C
1
-C
20
-alkyl groups such as methyl group; R
3
and R
4
are C
1
-C
20
-alkyl groups optionally containing silicon atoms or C
6
-C
20
-aryl groups, such as methyl, tert-butyl, phenyl, trimethylsilyl groups; R
6
, R
7
, R
8
and R
9
are C
1
-C
20
-alkyl groups such as methyl, tert-butyl, A is sulfur and B is CH.
A further object of the present invention is a metallocene compound of formula (1)
SiR
1
R
2
LQMXp  (I)
Wherein R
1
, R
2
, L, Q, M, X and p are described above.
Non-limiting examples of metallocene compounds suitable for use in the process of the invention are: dimethylsilandiyl-(tetramethylcyclopentadienyl)-7-(2,5-dimethylcyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-(tetraethylcyclopentadienyl)-7-(2,5-dimethylcyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-(tetraethylcyclopentadienyl)-7-(2.5-dimethylcyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-7-(2,5-dimethyl-cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)-7-(cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-7-(2,5-diethyl-cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)-7-(cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-7-(2,5-diisopropyl-cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)-7-(cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-7-(2,5-ditertbutyl-cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)-7-(cyclopentadienyl-1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandiyl-7-(2,5-ditrimethylsilyl-cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)-7-(cyclopentadienyl-[1,2-b:4,3-b′]-dithiophene)zirconium dichloride and dimethyl, dimethylsilandi

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