1. Field of the Art
This invention concerns olefin polymerization catalysts and olefin polymer production methods that use the olefin polymerization catalysts. More specifically, this invention concerns olefin polymerization catalysts, which contain prescribed compounds and with which xcex1-olefins can be copolymerized efficiently, and olefin polymer production methods using these polymerization catalysts.
2. Prior Arts and Themes Thereof
Olefin polymers and olefin copolymers, as represented by polyethylene and polypropylene, are excellent in heat resistance, resistance against aging, chemical resistance, and the like, and are used as general-purpose resins in a wide variety of industrial fields, such as automobile parts, and the like. Ziegler-Natta catalysts, as represented by titanium catalysts, which are comprised of a titanium compound and an organic aluminum compound, and vanadium catalysts, which are comprised of a vanadium compound and an organic aluminum compound, are known as catalysts used in the production of such olefin polymers.
However, titanium catalysts are not adequate in polymerization activity. The olefin polymers that are obtained using titanium catalysts are therefore low in molecular weight and wide in molecular weight distribution. Also, olefin copolymers that are obtained using a titanium catalyst are insufficient in terms of random copolymerization, have a broad distribution of composition, and copolymers with adequate mechanical strength are thus difficult to obtain with this type of catalyst. Meanwhile, with vanadium catalysts, though the random copolymerization characteristics are improved, the composition distribution becomes narrow, and though the mechanical characteristics also become improved, these characteristics still cannot be considered to be sufficient.
Metallocene catalysts, comprised of a transition metal compound and an aluminoxane, have been proposed as catalysts that can take the place of Ziegler-Natta catalysts. For example, Japanese Patent Publication No. Hei-4-12283 discloses an olefin polymerization method using a catalyst comprised of a transition metal compound and an aluminoxane. A catalyst comprised of a zirconium hydride compound, having a group with conjugate xcfx80 electrons as the ligand, and an aluminoxane is disclosed in Japanese Patent Publication No. Hei-5-80493. This patent publication also discloses a method for producing a polymer or copolymer with a molecular weight distribution (weight average molecular weight/number average molecular weight) of 1.97 to 2.15 by polymerizing ethylene or propylene or copolymerizing ethylene with an xcex1-olefin of 3 to 10 carbons and a non-conjugated polyene of 5 to 20 carbons under the presence of the abovementioned catalyst.
Besides the abovementioned metallocene catalysts, it is also known that ethylene and an xcex1-olefin can be copolymerized using metallocene compound, having a structure of silicon atoms, and the like, (Japanese Laid-open Patent Publication No. Sho-60-35007 and Japanese Laid-open Patent Publication No. Hei-3-12406), or using a geometrically constrained metallocene compound (CGCT: Japanese Laid-open Patent Publication No. Hei-3-163088).
However, the synthesis of a compound having a metallocene ligand (that is, a compound having a group with a cyclopentadiene ring structure as the ligand) requires a synthesis process of two to five stages. Also, if metallocene catalysts with one cyclopentadienyl group and non-cross-linked metallocene catalysts with two cyclopentadienyl groups are used, which can be synthesized relatively readily, the a-olefin polymerization activity is low and the ethylenexe2x80x94xcex1-olefin copolymer that is produced has a low xcex1-olefin content of approximately 5 weight %.
Besides metallocene catalysts, it is also known that olefins can be polymerized using a transition metal compound that is bonded with oxygen or another heteroatom. For example, Japanese Laid-open Patent Publication No. Hei-2-145606 discloses a method of polymerizing olefins using a product, obtained from bis(2-hydroxy-3-t-butyl-5-methylphenyl) sulfide and vanadium oxytrichloride, and methyl aluminoxane. However, a large quantity of methyl aluminoxane, which is expensive, must be used in this method.
Furthermore, Japanese Laid-open Patent Publication No. Hei-5-230133 and Japanese Laid-open Patent Publication No.Hei-6-192330 disclose methods of polymerizing olefins using 2,2xe2x80x2-thiobis(6-t-butyl-4-methylphenol) titanium dichloride, triisobutylaluminum, and a boron compound. However, a large quantity of triisobutylaluminum must be used in these methods.
The present invention has been made to solve the above problems and an object thereof is to present olefin polymerization catalysts with which polymers of high molecular weight can be obtained at high yields. In particular, an object of the present invention is to provide olefin polymerization catalysts with which copolymerization of xcex1-olefins with 4 or more carbons and especially 6 or more carbons can be performed at high yield. Another object of this invention is to provide catalysts with which the catalytic.components can be synthesized readily and with which the content of organic aluminum compound is low. Yet another object of this invention is to provide methods of producing olefin polymers using the abovementioned catalysts.
The olefin polymerization catalyst of the first aspect of this invention is characterized in containing a compound (a), which is expressed by the general formula (1) indicated below, a below-described compound (b), and a below-described compound (c).
Compound (a): 
In formula, (1), each of A1 and A2 has an atom which is bonded to M and wherein A1 and A2 are selected from a substituted nitrogen atom, an oxygen atom, a substituted silicon atom, a substituted phosphorus atom a sulfur atom and a substituted sulfur atom, and A1 and A2 may be the same as or may differ from each other. Each of R1 and R2 is a hydrocarbon group with 1 to 20 carbons or a hydrocarbon group with 1 to 20 carbons and containing a heteroatom, R1 and R2 may be bonded together and be the same as or may differ from each other. Each of B has an atom which is bonded to the abovementioned R1 and R2 and is selected from a substituted nitrogen atom, an oxygen atom, a substituted phosphorus atm, a sulfur atom, a substituted sulfur atom, a substituted silicon atom, rind a carbon atom which is part of a curbonyl group. M is a metal atom of group 5 (VA) of the periodic table. X has an atom which is bonded to M and which is selected from a halogen atom, a carbon atom, a substituted nitrogen atom, an oxygen atom, a substituted silicon atom, a substituted phosphorus atom, a sulfur atom and a substituted sulfur atom.
Compound (b): Compound (b) is at least one type of compound selected from the group consisting of organic aluminum compounds expressed by the general formula (2) indicated below.
(R3)nAlZ3xe2x88x92nxe2x80x83xe2x80x83(2)
In formula (2), R3 is a hydrocarbon group with 1 to 20 carbon atoms. Z is the hydrogen atom, a halogen atom, or an alkoxyl group. n takes on a value of 1 to 3.
Compound (c): Compound (c) is an ionized ionic compound.
The olefin polymerization catalyst of the second aspect of this invention is characterized in containing a reaction product (f), which is obtained by reacting a compound (d), expressed by the genera formula (3) indicated below, and a compound (e), expressed by the general formula (4) indicated below, a below-described compound (b), and a below-described compound (c).
Compound (d): M(O)X3xe2x80x83xe2x80x83(3)
In formula (3), M is a metal atom of group 5 (VA) of the periodic table. X has an atom which is bonded to M and which is selected from a halogen atom, a carbon atom, a substituted nitrogen atom, an oxygen atom a substituted silicon atom, a substituted phosphorus atom, a sulfur atom and a substituted sulfur atom.
Compound (e): C1xe2x80x94A1xe2x80x94R1xe2x80x94Bxe2x80x94R2xe2x80x94A2xe2x80x94C2xe2x80x83xe2x80x83(4)
In formula (4), each of A1 and A2 has an atom which is bonded to C1 or C2 and A1and A2 are selected from a substituted nitrogen atom an oxygen atom, a substituted silicon atom, a substituted phosphorus atom, a sulfur atom, and a substituted sulfur atom, and A1 and A2 may be the same as or may differ from e other. Each of R1 and R2 is a hydrocarbon group with 1 to 20 carbons or a hydrocarbon group with 1 to 20 carbons containing a heteroatom. R1 and R2 may be bonded together and may be the same as or may differ from each other, Each of B has an atom which is bonded to the abovementioned R1 and R2 and B is selected from a substituted nitrogen atom, an oxygen atom, a substituted phosphorus atom, a sulfur atom, a substituted sulfur atom, a substituted silicon atom, and a carbon atom which is part of a carbonyl group. Each of C1 and C2 is one type of atom selected from a hydrogen atom, lithium atom, sodium atom, and potassium atom and C1 and C2 may be the same as or may differ from each other.
Compound (b): Compound (b) is at least one type of compound selected from the group consisting of organic aluminum compounds expressed by the general formula (2) indicated below.
(R3)nAlZ3xe2x88x92nxe2x80x83xe2x80x83(2)
In formula (2), R3 is a hydrocarbon group with 1 to 20 carbon atoms. Z is a hydrogen atom, a halogen atom, or an alkoxyl group. n takes on a value of 1 to 3.
Compound (c): Compound (c) is an ionized ionic compound.
The olefin polymer production method of the third aspect of this invention is characterized in that an olefin is polymerized using the above-described polymerization catalyst of the first aspect of this invention.
The olefin polymer production method of the fourth aspect of this invention is characterized in that an olefin is polymerized using the above-described polymerization catalyst of the second aspect of this invention.
The olefin polymerization catalysts of this invention make it possible for polymers of high degree of copolymerization and high molecular weights to be obtained at high yields. Also, with these catalysts, the catalytic components may be obtained by a simple method. Furthermore, the amount of expensive organic aluminum compound used can be made small. Residual catalysis can thus be prevented.
Also, the olefin polymerization catalysts of this invention are effective for the polymerization of olefins and, in particular, make it possible for polymers of high copolymerization properties and high molecular weights to be obtained.
Furthermore, the production methods of this invention make it possible for polymers of high degree of copolymerization and high molecular weights to be obtained at high yields.