Olefin polymerization catalyst material and process for its...

Details Olefin polymerization catalyst material and process for its... Olefin polymerization catalyst material and process for its...

2000-04-21

2003-01-14

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...

C526S133000, C526S172000, C502S104000, C502S120000, C502S129000, C502S167000

Reexamination Certificate

active

06506858

ABSTRACT:

This invention relates to catalyst materials, their preparation and their use in olefin polymerization.
The use of metallocenes, e.g. cyclopentadienyl or indenyl complexes of metals such as Ti, Zr and Hf, in olefin polymerization catalyst systems is well known.
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 (B(C
6
F
5
)
3
) or triphenylcarbenium tetraphenylpentafluoroborate ((C
6
H
5
)
3
C
+
B
−
(C
6
F
5
)
4
)).
However, where a metallocene procatalyst which does not contain alkyl (especially methyl) ligands is used, it is necessary to react the procatalyst with a material which serves to introduce alkyl ligands. MAO can perform this function but in the case of non-aluminoxane cocatalysts it is necessary to react the metallocene with an alkylating agent so as to introduce the alkyl ligands.
This however has the disadvantage that the alkylated metallocene has to be separated from the excess reagents and by-products and purified before being heterogenised, ie. loaded onto a catalyst support.
It has now been found that alkylation of certain procatalysts, e.g. metallocene procatalysts may be effected in a particularly simple and straightforward manner by loading the procatalyst onto a particulate catalyst support which has been pre-treated with an alkylating agent.
Thus viewed from one aspect the invention provides a process for the preparation of a catalyst material, said process comprising the steps of:
(a) treating a particulate support material with an alkylating agent;
(b) contacting the alkylating agent treated support material with a procatalyst, e.g. a metallocene procatalyst; optionally
(c) contacting the support material with an ionic catalyst activator; and optionally
(d) recovering the catalyst-carrying support material.
In the process of the invention, the particulate support material is preferably an inorganic material, especially preferably a metal or pseudo metal oxide such as silica, alumina or zirconia or a mixed oxide such as silica-alumina, in particular silica, alumina or silica-alumina. Particularly preferably, the support material is acidic, e.g. having an acidity greater than or equal to silica, more preferably greater than or equal to silica-alumina and even more preferably greater than or equal to alumina. The acidity of the support material can be studied and compared using the TPD (temperature programmed desorption of gas) method. Generally the gas used will be ammonia. The more acidic the support, the higher will be its capacity to adsorb ammonia gas. After being saturated with ammonia, the sample of support material is heated in a controlled fashion and the quantity of ammonia desorbed is measured as a function of temperature.
Especially preferably the support is a porous material so that the metallocene may be loaded into the pores of the support, e.g. using a process analogous to those described in WO94/14856 (Mobil), WO95/12622 (Borealis) and WO96/00243 (Exxon). The particle size is not critical but is preferably in the range 5 to 200 &mgr;m, more preferably 20 to 80 &mgr;m.
Before treatment with the alkylating agent, the particulate support material is preferaby calcined, ie heat treated, preferably under a non-reactive gas such as nitrogen. This treatment is preferably at a temperature in excess of 100° C., more preferably 200° C. or higher, e.g. 200-700° C., particularly about 300° C. The calcination treatment is preferably effected for several hours, e.g. 2 to 30 hours, more preferably about 10 hours. It is thought that this calcination has the effect of optimizing the reaction of the alkylating agent with acid hydroxyl groups on the support material.
The treatment of the support with the alkylating agent may be effected using an alkylating agent in a gas or liquid phase, e.g. in an organic solvent for the alkylating agent. The alkylating agent may be any agent capable of introducing alkyl groups, preferably C
1-6
alkyl groups and most especially preferably methyl groups. Such agents are well known in the field of synthetic organic chemistry. Preferably the alkylating agent is an organometallic compound, especially an organoaluminium compound (such as trimethylaluminium (TMA), dimethyl aluminium chloride, triethylaluminium) or a compound such as methyl lithium, dimethyl magnesium, triethylboron, etc.
The quantity of alkylating agent used will depend upon the number of active sites on the surface of the carrier. Thus for example, for a silica support, surface hydroxyls are capable of reacting with the alkylating agent. In general, an excess of alkylating agent is preferably used with any unreacted alkylating agent subsequently being washed away.
Where an organoaluminium alkylating agent is used, this is preferably used in a quantity sufficient to provide a loading of at least 0.1 mmol Al/g carrier, especially at least 0.5 mmol Al/g, more especially at least 0.7 mmol Al/g, more preferably at least 1.4 mmol Al/g carrier, and still more preferably 2 to 3 mmol Al/g carrier. Where the surface area of the carrier is particularly high, lower aluminium loadings may be used. Thus for example particularly preferred aluminium loadings with a surface area of 300-400 m
2
/g carrier may range from 0.5 to 3 mmol Al/g carrier while at surface areas of 700-800 m
2
/g carrier the particularly preferred range will be lower.
Following treatment of the support material with the alkylating agent, the support is preferably removed from the treatment fluid and any excess treatment fluid is allowed to drain off.
The treated support material is then loaded with the procatalyst, preferably using a solution of the procatalyst in an organic solvent therefor, e.g. as described in the patent publications referred to above. Preferably, the volume of procatalyst solution used is from 50 to 500% of the pore volume of the carrier, more especially preferably 80 to 120%. The concentration of procatalyst compound in the solution used can vary from dilute to saturated depending on the amount of metallocene active sites that it is desired be loaded into the carrier pores.
The metal of the procataylst may be any metal effective in olefin polymerization, e.g. a metal of group 3 to 8, especially preferably a transition metal or lanthanide, in particular Ti, Zr or Hf.
The procatalyst of use according to the invention may be a metallocene or a non-metallocene although metallocene procataylsts are preferred.
Where the procatalyst is a non-metallocene, i.e does not comprise a cyclopentadienyl ligand or ligand derived from a cyclopentadienyl moiety such as indenyl, the metal atom is coordinated by at least one suitable sigma or &eegr; bonding ligand, preferably a &eegr; bonding ligand. In a preferred embodiment the &eegr; bonding ligand is a heterocyclic group, especially one comprising a fused ring system. In a most preferred embodiment said ring system comprises 3 nitrogen atoms attached to the same carbon atom, one of said atoms forming part of two fused rings. Suitable heterocyclic ligands of this type are of formula
where groups R
1
, R
2
, R
3
and R
4
are the same or different selected from the group of H, C
1
-C
12
alkyl, alkenyl, aryl (phenyl preferable), alkylaryl, or the groups R
1
, R
2
, R
3
and R
4
may contain silicon atoms instead of one or more carbon atoms, preferably they are SiH
3
, SiH
2
R
5
, SiHR
6
R
3
, SiR
8
R
9
R
10
groups where groups R
5
to R
10
are also the groups recited above. The substituent groups may be also a combination of several groups recited above. R
1
to R
4
can also be taken together to form bridged structures. In the presence of a base a balance exists in the formula (2) between two ionic isomeric structures which are presented in the right of the formula (2). Formula (2) preferably represents a triaza bicyclo alkenyl, more preferably a 1,5,7-triaza

Affiliated with

Also associated with

Rating

Olefin polymerization catalyst material and process for its... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Olefin polymerization catalyst material and process for its..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Olefin polymerization catalyst material and process for its... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3011184