Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
1999-06-22
2001-01-30
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S103000, C502S118000, C502S125000, C502S128000, C502S150000, C502S172000, C526S142000, C526S143000, C526S144000, C526S348600, C526S916000
Reexamination Certificate
active
06180554
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a catalyst system containing
a) an organoaluminum compound
b) a metal compound selected from a metal of subgroups IV to VI of the periodic system
c) a reactivator in a molar ratio of 0.5 to 100 relative to said metal compound
wherein said reactivator comprises a mono- or dihalocarboxylic acid alkyl ester of the following formula:
is used as the reactivator, wherein X is a C
1-6
alkyl or C
1-6
alkoxy group, Y is Cl, Br or H; Z is Cl or Br; and R is a C
1-6
alkyl group and to the use thereof in a process for the production of (co)polymers of one of more &agr;-olefins and optionally a diene having unconjugated double bonds or a conjugated diene by (co)polymerization, and to the polymers producible using the catalyst according to the present invention.
BACKGROUND OF THE INVENTION
It is known to polymerize ethylene with other &agr;-olefins and optionally with unconjugated dienes or to polymerize olefins or conjugated dienes alone in the presence of organometallic (Ziegler-Natta) mixed catalysts (Encycl. Polym. Sci. Eng., 2
nd
edition, volume 6, pages 522 et seq., Wiley, N.Y. , 1986). Polymerization is performed in solution, as a suspension or in the gas phase. The catalysts used are transition metal compounds of subgroups IV to VI of the periodic system (usually vanadium compounds in valence state +3 to +5) together with organometallic compounds of main groups I to III (usually organoaluminum compounds). Such catalytic systems exhibit very high initial activity, which, however, quickly falls due to the rapid reduction of the transition metal to low valence states (for example +2), which are inactive for polymerization purposes. Reactivators, which reoxidize the transition metal compound to return it's valence states which are active for polymerization purposes, are accordingly used in order to increase polymer yields (for example expressed as the quantity of polymer formed in g per g of transition metal).
The most efficient reactivators for catalysts containing vanadium are substances containing chlorine. Polychlorinated compounds, such as for example trichloroacetic acid esters (DE 1,570,726), perchlorocrotonic acid esters (DE 1,595,442) or hexachlorocyclopentadiene (DE 1,495,698) have proven to be effective in practice. However, these reactivators have the disadvantage that the resultant copolymers exhibit a very high chlorine content. The chlorine content has a negative effect on many polymer properties, primarily aging resistance. Moreover, polymers containing chlorine give rise to increased corrosion on plant components during working up of the copolymer after polymerization and on processing plant. Compounds having a lower chlorine content, for example mono- and dichloromalonic acid esters (CA 272,857, DE 2,344,267), usually exhibit low activity. In practice, this results in a low solids content in the polymer solution. Remedying this deficiency would require disproportionately large excesses of reactivator relative to the vanadium compound, which is economically disadvantageous. Effective compounds having a lower chlorine content have been described as reactivators in recent years, for example dichlorophenylacetic acid esters (EP 0,044,119 and 0,044,595). However, even when such reactivators are used, the chlorine content in the polymer may only be reduced to the necessary low level by means of costly polymer washing.
EP 0,680,976 discloses the use of arylhalomalonic esters as reactivators for Ziegler-Natta catalysts containing vanadium. While these compounds are indeed effective, in comparison with dichlorophenylacetic acid ethyl ester, twice the quantity of reactivators must be used in order to achieve satisfactory yields.
SUMMARY OF THE INVENTION
The object of the present invention is accordingly to provide a catalyst system for the (co)polymerization of at least one olefin and optionally a diene having unconjugated double bonds or a conjugated diene, which system comprises a reactivator which does not exhibit the disadvantages of the prior art.
This object is achieved according to the invention by the provision of a catalyst system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a catalyst system comprising
a) an organoaluminum compound,
b) a metal compound selected from a metal of subgroups IV to VI of the periodic system
c) a reactivator in a molar ratio of 0.5 to 100 relative to said metal compound
wherein said reactivator comprises a mono- or dihalocarboxylic acid alkyl ester of the following formula:
is used as the reactivator, wherein X is a C
1-6
alkyl or C
1-6
alkoxy group, Y is Cl, Br or H; Z is Cl or Br; and R is a C
1-6
alkyl group.
The group R may comprise a linear or branched or cyclic alkyl group having 1 to 6 carbon atoms, for example methyl, ethyl, n-propyl, i-propyl, n-butyl, sec.-butyl, i-butyl, tert.-butyl, n-pentyl, i-pentyl, n-hexyl, cyclopropyl or cyclohexyl.
The residue Z may be Cl or Br. Cl is preferred.
The residue Y may be H, Cl or Br. If Y is Cl or Br, Y=Z. Preferably, Y is Cl, since dichlorocarboxylic acid alkyl esters are respectively more highly active or lower in cost than monochlorocarboxylic acid alkyl esters or mono- or dibromocarboxylic acid alkyl esters.
The reactivator/transition metal molar ratio is between 0.5 and 100, preferably between 1 and 40.
Compounds of the general formula
X
y
AIR
3−y
may preferably be used as the organometallic compound a) of the catalyst system, wherein X is halogen and R is 1-6 alkyl and y is 0, 1 or 2. Methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec.-butyl, tert.-butyl, n-pentyl or n-hexyl may be considered as the alkyl group. Compounds which may be stated by way of example are ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum chloride, diisobutylaluminum chloride. The compounds may be used alone or as a mixture.
Any transition metal compounds of subgroups IV to VI of the periodic system may be used as the transition metal compound b), but vanadium compounds are particularly preferred. The compounds preferably comprise those of the general formula
X
y
MR
3−y
wherein M means V or VO, X means halogen, R means an acetyl-acetonate group or a C
1-6
alkoxy group and y is 1, 2, or 3. Linear or branched alkoxy groups may be considered as the alkoxy group, such as for example methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, sec.-butoxy, tert.-butoxy, n-pentyloxy or n-hexyloxy.
VCl
3
, VOCl
3
, vanadium trisacetylacetonate, vanadylbisacetyl-acetonate, alkylvanadates having 1 to 6 carbon atoms etc. may, for example, be used. The compounds may be used alone or as a mixture.
Compounds containing vanadium in oxidation state +4 are furthermore preferred, very particularly preferably VCl
4
.
The molar ratio of organometallic compound/transition metal compound is between 1 and 100, preferably between 2 and 50.
The olefins polymerizable using the catalyst system according to the invention are preferably ethylene or &agr;-olefins having 3 to 10 carbon atoms, for example propylene, 1-butylene, isobutylene, isoprene, 1-pentene, 1-hexene, 1-octene or 1-decene. Ethylene, propylene, isoprene and isobutylene are preferably used. If copolymers are being produced from ethylene, another &agr;-olefin and optionally a diene, propylene is preferably used as the second olefin (EPDM rubber). The ethylene content in the copolymer is in this case preferably between 25 and 85 wt. %, for rubbery copolymers preferably between 40 and 75 wt. %, in each case relative to the copolymer.
In most copolymers, unsaturated side chains are required for vulcanization. To this end, an unconjugated diene, preferably 5-ethylidene-2-norbornene, dicyclopentadiene or 1,4-hexadiene, is used as a third monomer. The concentration of the termonomer in the copolymer is 1 to 15 wt. %, preferably 1 to 10 wt. %, relative to the copolymer.
The catalyst system may also preferably be used to polymerize isobutylene with isoprene to produce butyl rubber. The proportion of isoprene i
Essert Thomas
Hoch Martin
Jansen Johannes-Rudolf
Sattler Andreas
Schneider J{umlaut over (u)}rgen
Bayer Aktiengesellschaft
Bell Mark L.
Cheung Noland J.
DiVerdi Michael J.
Gil Joseph C.
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