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
2003-04-10
2004-03-23
Choi, Ling-Siu (Department: 1713)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S103000, C502S152000, C526S160000, C526S943000, C526S348000, C526S125100, C556S028000
Reexamination Certificate
active
06710005
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to modification of aluminoxane. More particularly, the invention relates to modification of aluminoxane with glycol ether or polyether.
BACKGROUND OF THE INVENTION
Single-site catalysts are known. They can be divided into metallocenes and non-metallocenes. Metallocene single-site catalysts are transition metal compounds that contain cyclopentadienyl (Cp) or Cp derivative ligands. Non-metallocene single-site catalysts contain ligands other than Cp but have similar catalytic characteristics to the metallocenes. The non-metallocene single-site catalysts often contain heteroatomic ligands, e.g., boraary, pyrrolyl, azaborolinyl, indenoindolyl and quinolinyl.
Aluminoxane compounds are activators for single-site catalysts. There are many ways to make aluminoxane compounds. For instance, aluminoxanes can be produced by contacting a trialkylaluminum compound with water. See U.S. Pat. No. 5,041,585. Commonly used aluminoxane is methyl aluminoxane (MAO) or its derivatives.
Methods for modifying aluminoxanes are known. For instance, U.S. Pat. No. 6,340,771 teaches modifying MAO with sugar to make “sweet” MAO. Also, U.S. Pat. No. 5,543,377 teaches modifying aluminoxane compounds with ketoalcohols and &bgr;-diketones.
Single-site catalysts produce polyolefin having narrow molecular weight distribution. The uniformity of molecular weight distribution of single-site polyolefin, although improving tensile strength and other physical properties of polymer products, makes the thermal processing difficult. Many methods have been developed to improve processability of single-site polyolefin. U.S. Pat. No. 6,127,484, for example, teaches a multiple-zone, multiple-catalyst process for making polyethylene. The polymer produced has a broad molecular weight distribution and improved processability.
New methods for modifying aluminoxane compounds are needed. Ideally, the method would be inexpensive and easy to practice. Particularly, the modified aluminoxane would increase molecular weight distribution and improve the processability of single-site polyolefin.
SUMMARY OF THE INVENTION
The invention is a modified aluminoxane. The modified aluminoxane is prepared by treating an aluminoxane compound with glycol ether or polyether. The invention also provides a catalyst system for olefin polymerization. The catalyst system comprises the modified aluminoxane and a transition metal complex. The catalyst system produces polyolefin that has increased melt flow index, broadened molecular weight distribution, and improved thermal processability.
DETAILED DESCRIPTION OF THE INVENTION
The invention is a modified aluminoxane. The modified aluminoxane is prepared by treating an aluminoxane compound with glycol ether or polyether. By “treating,” we meant either chemically reacting or physically mixing, or both.
Suitable aluminoxane compounds include linear aluminoxanes having the formula:
R
1
2
AlO(R
2
AlO)
n
AlR
3
2
R
1
, R
2
, and R
3
are independently selected from the group consisting of C
1-20
hydrocarbyl radicals and n is from 0 to 50. Preferably, R
1
, R
2
, and R
3
are methyl group. Preferably, n is from 0 to 10.
Suitable aluminoxane compound also includes cyclic aluminoxanes having a repeating unit of
—[Al(R
4
)—O]—
R
4
is a C
1-20
hydrocarbyl. Preferably, R
4
is methyl group.
Suitable glycol ethers include monoalkyl and dialkyl ethers of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, cyclohexane-1,4-dimethanol, neopentyl glycol, and mixtures thereof. Examples of suitable glycol ethers are ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol dipropyl ether, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol monoethyl ether, propylene glycol diethyl ether, propylene glycol monopropyl ether, propylene glycol dipropyl ether, propylene glycol monobutyl ether, propylene glycol dibutyl ether, the like, and mixtures thereof. Preferably, the glycol ethers are monoalkyl ethers.
Suitable polyethers include polyethylene glycol, polyethylene glycol monoalkyl ethers, polyethylene glycol dialkyl ethers, polypropylene glycol, polypropylene glycol monoalkyl ethers, polypropylene glycol dialkyl ethers, the like, and mixtures thereof. Polyethers also include glycol ethers which have more than two glycol units, such as triethylene glycol, tripropylene glycol, and their mono- and dialkyl ethers.
The treatment can be carried out at a temperature from 0° C. to 200° C. Preferably, the temperature is from 20° C. to 40° C. The weight ratio of glycol ether or polyether to aluminoxane may be from 1:500 to 5:1, preferably from 1:100 to 1:1. Generally, the treatment takes place in an inert diluent or solvent, preferably under an inert atmosphere such as nitrogen. Suitable diluents and solvents include aliphatic and aromatic hydrocarbons, ethers, esters, and ketones. After the treatment, diluents and solvents may be removed.
Glycol ether- or polyether-treated aluminoxane compounds are activators for single-site catalysts. Single-site catalysts suitable for use in the present invention include transition metal complex having the general formula:
(L)
n
—M—(X)
m
M is a transition metal. Preferably, M is Zr, Ti, or Hf. More preferably, M is Zr.
X is an activatable ligand. “Activatable ligand” means a ligand which is able to be activated by the treated aluminoxane to facilitate olefin polymerization. X is independently selected from the group consisting of hydrogen, halides, C
1-10
hydrocarbyls, C
1-10
alkoxys, and C
5-10
aryloxys. The hydrocarbyl, alkoxy, and aryloxy ligands may also be substituted, for example, by halogen, alkyl, alkoxy, and aryloxy groups. Preferably, X is a halide. More preferably, X is chloride.
L is a ligand preferably selected from the group consisting of cyclopentadienyl, boraary, pyrrolyl, azaborolinyl, quinolinyl, indenoindolyl, and phosphinimine, the like, and mixtures thereof. These ligands provide the catalysts with “single-site” nature. That is, the catalyst has only one active site for olefin polymerization and thus provides the polyolefin with relatively narrow molecular weight and composition distributions.
Cyclopentadienyl ligands include substituted cyclopentadienyl such as methyl, isopropyl, and butyl cyclopentadienyl ligands. Cyclopentadienyl ligands also include substituted and non-substituted indenyl and fluorenyl ligands. Cyclopentadienyl based single-site catalysts are known, see, e.g., U.S. Pat. Nos. 4,404,344, 4,769,510, 6,160,066, and 5,955,625, the teachings of which are incorporated herein by reference.
Boraary, pyrrolyl, azaborolinyl, quinolinyl, and phosphinimine based single-site catalysts are also known, see, e.g., U.S. Pat. Nos. 6,034,027, 5,539,124, 5,756,611, 5,637,660, 6,340,771, and 6,350,831, the teachings of which are incorporated herein by reference. These heteroatom-containing can also be substituted.
Numbers n and m depend on the valence of the transition metal. The sum of n and m equals to the valence of the metal. Number n is preferably 1 or greater.
Two L ligands can be bridged. Groups that can be used to bridge the ligands include, for example, methylene, ethylene, 1,2-phenylene, and dialkyl silyls. Examples are —CH
2
—, —CH
2
—CH
2
—, and —Si(CH
3
)
2
—. Bridging changes the geometry around the transition metal and can improve catalyst activity and other properties such as comonomer incorporation.
The catalyst may be immobilized on a support. The support is preferably a porous material such as inorganic oxides and chlorides, organic polymer resins, and mixtures thereof. Preferred inorganic oxides include oxides of Group 2, 3, 4, 5, 13, or 14 elements. Preferred supports include silica, alumina, silica-aluminas, magnesias, titanias, zirconias, magnesium chloride, clay, and cro
Guo Shao-Hua
Wang Shaotian
Choi Ling-Siu
Shao-Hua Guo
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