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
2001-04-09
2002-07-09
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, C502S113000, C502S115000, C526S114000
Reexamination Certificate
active
06417129
ABSTRACT:
TECHNICAL FIELD
This invention relates to a mixed metal catalyst, which will be effective in producing a resin having low and high density components.
BACKGROUND INFORMATION
For film blowing applications, it is desirable to have at least some high molecular weight, high density resin to increase bubble stability together with lower molecular weight, low density resin for processability. While this can be accomplished in two or more reactors, it would be desirable commercially to produce a high density/low density resin in a single reactor from the point of view of efficiency. Thus, industry is seeking catalysts, which are effective in the production of such a resin.
DISCLOSURE OF THE INVENTION
An object of this invention, therefore, is to provide a catalyst composition, which will produce a resin having both high and low density characteristics in a single reactor. Other objects and advantages will become apparent hereinafter.
According to the present invention such a catalyst composition has been discovered. The composition comprises (i) a supported or unsupported magnesium/titanium based catalyst precursor including an electron donor and (ii) a lanthanide catalyst precursor represented by the following formula: Cp
a
LnR
b
b
L
c
wherein Cp is a cyclopentadienyl or substituted cyclopentadienyl ligand; Ln is a lanthanide metal; R
b
is a hydride, alkyl, silyl, halide, or aryl group; L is an electron donor; a+b is the valence of the lanthanide metal; and c is a sufficient amount of electron donor to stabilize the lanthanide metal.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
The supported or unsupported magnesium/titanium based catalyst including an electron donor can be exemplified by one where the precursor is formed by spray drying and used in slurry form. Note: the terms catalyst and catalyst precursor or precursor will be used interchangeably in this specification. Such a catalyst precursor, for example, contains titanium, magnesium, and an electron donor, and, optionally, an aluminum halide. The precursor is introduced into a hydrocarbon medium such as mineral oil to provide a slurry. This spray dried catalyst is described in U.S. Pat. No. 5,290,745. Other processes are described in U.S. Pat. Nos. 5,601,742 and 4,482,687. In whichever manner the catalyst precursor is produced, the precursor is preferably suspended in an inert, high viscosity fluid, e.g., a moderately high viscosity mineral oil.
A typical magnesium/titanium based catalyst system can be described as follows: The precursor can have the formula Mg
d
Ti(OR
e
)
e
X
f
(ED)
g
wherein R
e
is an aliphatic or aromatic hydrocarbon radical having 1 to 14 carbon atoms or COR′ wherein R′ is an aliphatic or aromatic hydrocarbon radical having 1 to 14 carbon atoms; each OR
e
group is the same or different; X is independently chlorine, bromine or iodine; ED is an electron donor; d is 0.5 to 56; e is 0, 1, or 2; f is 2 to 116; and g is 1.5d+2. It is prepared from a titanium compound, a magnesium compound, and an electron donor. Titanium compounds, which are useful in preparing these precursors, have the formula Ti(OR
e
)
e
X
h
wherein R
e
, X, and e are as defined above; h is an integer from 1 to 4; and e+h is 3 or 4. Some specific examples of titanium compounds are TiCl
3
; TiCl
4
; Ti(OC
2
H
5
)
2
Br
2
; Ti(OC
6
H
5
)Cl
3
; and Ti(OCOCH
3
)Cl
3
. TiCl
3
and TiCl
4
are preferred compounds. The magnesium compounds include magnesium halides such as MgCl
2
, MgBr
2
, and MgI
2
. Anhydrous MgCl
2
is a preferred compound. About 0.5 to about 56, and preferably about 1 to about 10, moles of the magnesium compounds are used per mole of titanium compound.
The electron donor is an organic Lewis base, liquid at temperatures in the range of about 0 degrees C. to about 200 degrees C., in which the magnesium and titanium compounds are soluble. The electron donor can be an alkyl ester of an aliphatic or aromatic carboxylic acid, an aliphatic ketone, an aliphatic amine, an aliphatic alcohol, an alkyl or cycloalkyl ether, or mixtures thereof, each electron donor having 2 to 20 carbon atoms. Among these electron donors, the preferred are alkyl and cycloalkyl ethers having 2 to 20 carbon atoms; dialkyl, diaryl, and alkylaryl ketones having 3 to 20 carbon atoms; and alkyl, alkoxy, and alkylalkoxy esters of alkyl and aryl carboxylic acids having 2 to 20 carbon atoms. The most preferred electron donor is tetrahydrofuran. Other examples of suitable electron donors are methyl formate, ethyl acetate, butyl acetate, ethyl ether, dioxane, di-n-propyl ether, dibutyl ether, ethanol, 1-butanol, ethyl formate, methyl acetate, ethyl anisate, ethylene carbonate, tetrahydropyran, and ethyl propionate. Alcohol containing electron donors which react with the transition metal halide compounds are not preferred.
While an excess of electron donor is used initially to provide the reaction product of titanium compound and electron donor, the reaction product finally contains about 1 to about 20 moles of electron donor per mole of titanium compound and preferably about 1 to about 10 moles of electron donor per mole of titanium compound.
Supports can be used with the magnesium/titanium based catalyst precursor although they are not preferred. In those cases where it is desired to support the precursor, silica is the preferred support. Other suitable supports are inorganic oxides such as aluminum phosphate, alumina, silica/alumina mixtures, silica modified with an organoaluminum compound such as triethylaluminum, and silica modified with diethyl zinc. A typical support is a solid, particulate, porous material essentially inert to the polymerization. It is used as a dry powder having an average particle size of about 10 to about 250 microns and preferably about 30 to about 100 microns; a surface area of at least 200 square meters per gram and preferably at least about 250 square meters per gram; and a pore size of at least about 100 angstroms and preferably at least about 200 angstroms. Generally, the amount of support used is that which will provide about 0.1 to about 1.0 millimole of titanium per gram of support and preferably about 0.4 to about 0.9 millimole of titanium per gram of support. Impregnation of the above mentioned catalyst precursor into a silica support can be accomplished by mixing the precursor and silica gel in the electron donor solvent or other solvent followed by solvent removal under reduced pressure. When a support is not desired, the catalyst precursor can be used in liquid form.
Cocatalysts that are compatible with the magnesium/titanium based catalyst precursor are generally used in the polymerization process. Cocatalysts that can be used with the described precursor are compounds of the formula R
n
AlX
3-n
wherein each R is independently a saturated aliphatic hydrocarbon radical having 1 to 14 carbon atoms; each X is a halogen, preferably independently chlorine, bromine, or iodine; and n is 1 to 3. Examples of the R radical are methyl, ethyl, n-butyl, isobutyl, n-hexyl and n-octyl. The cocatalyst is preferably added to the reactor in the same inert diluent as the catalyst precursor. Preferred cocatalysts include diethyl aluminum chloride, triethyl aluminum, tri-n-hexyl aluminum, dimethyl aluminum chloride, tri-n-octyl aluminum, and mixtures thereof. The cocatalysts can also be represented by the formulas R
3
Al or R
2
AlX wherein each R is independently alkyl, cycloalkyl, aryl, or hydrogen; at least one R is hydrocarbyl; and two or three R radicals can be joined to form a heterocyclic structure. Each R, which is a hydrocarbyl radical, can have 1 to 20 carbon atoms, and preferably has 1 to 10 carbon atoms. X is a halogen, preferably chlorine, bromine, or iodine.
Examples of hydrocarbyl aluminum cocatalysts, in addition to those mentioned above, are as follows: tri-isobutylaluminum, di-isobutyl-aluminum hydride, dihexylaluminum hydride, di-isobutyl-hexylaluminum, isobutyl dihexylaluminum, trimethylaluminum, tripropylaluminum, triisopropylaluminum, tri-n-butylaluminum, tridecylaluminum, tridodecylaluminum, tr
Bell Mark L.
Pasterczyk J.
Union Carbide Chemicals & Plastics Technology Corporation
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