Olefin polymerization catalyst and a process for producing polyolefins by the use of said catalyst

An olefin polymerization catalyst comprising a solid catalyst (I) and an organometallic compound (II), wherein said solid catalyst (I) is obtainable by reacting an organomagnesium compound (a) soluble in hydrocarbon solvent and represented by the following formula: EQU MgR.sup.1.sub.p R.sup.2.sub.q X.sub.r (in the formula, R.sup.1 and R.sup.2, identical or different, represent a secondary or tertiary alkyl group having 4-6 carbon atoms, X represents a negative group containing O, N or S atom, p and q represent a number of 0-2, r represents a number of 0-1, and p, q and r satisfy: p+q+r=2) with a compound of titanium or vanadium having at least one halogen atom (b), has a high activity, is uniform, has a high density, is suitable for continuous polymerization of olefins, and enables to omit the catalyst removal step after the polymerization reaction. An olefin polymerization catalyst obtainable by replacing the solid catalyst (I) with a solid type catalyst (I') obtainable by further reacting solid catalyst (I) with compound (b) or with an organic or inorganic compound of aluminum, silicon, tin or antimony (c), and catalysts obtainable by adding a halogenated hydrocarbon (III) to the above-mentioned olefin polymerization catalysts give polyolefins having a broad molecular weight distribution.

TECHNICAL FIELD 
This invention relates to a novel olefin polymerization catalyst having a 
high activity. 
BACKGROUND ART 
The low pressure production process of polyethylene using a catalyst 
comprising an organomagnesium compound and a transition metal compound is 
already publicly known in the patent of K. Ziegler (Japanese Patent 
Publication No. 1546/1957). However, organomagnesium compound itself is 
insoluble in the inert hydrocarbon media used for the synthesis of 
catalyst and the polymerization reaction, so that it has never been used 
effectively and no success has ever been achieved in obtaining a high 
activity therefrom. 
As catalysts of which activity is enhanced by using an organomagnesium 
compound in a specific form, there are known systems using, for example, 
an ether complex of organomagnesium halogenide, the so-called Grignard 
reagent, or one using organomagnesium alkoxide (Japanese Patent 
Publication No. 40,959/1972; Japanese Patent Kokai (Laid-Open) No. 
19,274/1971). Though these catalysts exhibit a considerably high activity 
per atom of transition metal, they are still insufficient to omit the 
catalyst removal step of the polyethylene production process completely in 
that the halogen remains in the liquid reaction mixture to such an extent 
as being not disregarded. 
The present inventors had already discovered a series of catalyst systems 
using a complex compound soluble in inert hydrocarbons. These catalysts 
systems comprise an organomagnesium compound together with an 
organoaluminum compound, an organozinc compound, an organoboron compound 
and an organoberyllium compound, respectively. (U.S. Pat. Nos. 3,989,878, 
4,004,071, 4,027,087). These catalyst systems have a much higher activity 
than the above-mentioned disclosed catalysts and enable to omit the 
catalyst removal step completely. 
DISCLOSURE OF INVENTION 
As the result of further studies on the catalysts using an organomagnesium 
component, it was found that, surprisingly, a quite excellent catalyst of 
high activity for olefin polymerization can be obtained by the reaction 
between an organometallic compound and a specific solid obtainable by 
reacting a specific organomagnesium compound soluble in inert hydrocarbons 
with a titanium or vanadium compound, instead of using the above-mentioned 
complex of organomagnesium compound and organometallic compound. Based on 
this finding, this invention was accomplished. 
Thus, this invention provides an olefin polymerization catalyst comprising 
a solid catalyst (I) and an organometallic compound (II), said solid 
catalyst (I) being obtained by reacting an organomagnesium compound (a) 
soluble in hydrocarbon solvents and represented by the following formula: 
EQU MgR.sup.1.sub.p R.sup.2.sub.q X.sub.r 
wherein R.sup.1 and R.sup.2 may be identical or different, and represent a 
secondary or tertiary alkyl group having 4-6 carbon atoms, X represents a 
negative group containing O, N or S atom, p and q represent a number of 0 
to 2, r represents a number of 0 to 1, and p, q and r satisfy an equation: 
p+q+r=2, with a titanium or vanadium compound (b) having at least one 
halogen atom. This invention also provides a process for producing 
polyolefins by the use of said catalyst. 
The first characteristic feature of the catalyst of this invention is that 
the catalytic efficiency is extremely high. Owing to the effect, the 
quantity of catalyst residue such as transition metal, halogen and the 
like remaining in polymer is small and the catalyst is suitable for use in 
a process from which the step of catalyst removal is omitted. The second 
characteristic feature is that the formed polymer has quite excellent 
particle characteristics such that the particle size of polymer is 
uniform, the polymer contains no coarse particles making trouble in the 
continuous polymerization, and the polymer has a high bulk density. The 
third characteristic feature is that the production of a polymer having a 
high molecular weight, a high stiffness, a sharp molecular weight 
distribution and a high impact strength can be achieved. 
Another aspect of this invention provides an olefin polymerization catalyst 
comprising a combination of solid type catalyst (I') and an organometallic 
compound (II), said solid type catalyst (I') being a reaction product 
between a solid catalyst (I) to be combined with an organometallic 
compound (II) and an inorganic or organic aluminum, silicon, tin or 
antimony compound and/or a reaction product between said solid catalyst 
(I) and a titanium or vanadium compound having at least one halogen atom. 
By the use of this catalyst, a polymer having a relatively broad molecular 
weight distribution is obtained. 
Still another aspect of this invention provides also an olefin 
polymerization catalyst in which the above-mentioned combination of solid 
catalyst (I) or solid type catalyst (I') and organometallic compound (II) 
is further combined with a halogenated hydrocarbon (III). By the use of 
this catalyst, it is also possible to produce a polymer having a broad 
molecular weight distribution and suitable for blow molding and formation 
of film and sheet by means of extrusion process. 
BEST MODE FOR CARRYING OUT THE INVENTION 
Hereunder, the various components used in the catalyst of this invention 
will be explained in detail. The organomagnesium compound (hereinafter 
referred to as component (a)) used for the synthesis of solid catalyst (I) 
is represented by the following formula: 
EQU MgR.sup.1.sub.p R.sup.2.sub.q X.sub.r 
wherein R.sup.1, R.sup.2, X, p, q and r are as defined above. 
In the formula mentioned above, the hydrocarbon group represented by 
R.sup.1 and R.sup.2 is a secondary or tertiary alkyl group having 4-6 
carbon atoms. Its typical examples include sec-C.sub.4 H.sub.9, 
##STR1## 
and the like. They are preferably a secondary alkyl group, and 
particularly preferably a sec-butyl group. Also, it is possible to use 
mixtures of them with magnesium compounds having straight chain alkyl 
group so far as they can retain a solubility in inert hydrocarbon. 
Examples of the negative group containing O, N or S atom, represented by 
X, include alkoxy groups, siloxy groups, aryloxy groups, amino groups, 
amido groups, 
##STR2## 
--SR", .beta.-ketoacid residues and the like, wherein R, R' and R" are 
hydrocarbon groups. Preferably alkoxy groups or siloxy groups are used. p 
and q are each a number from 0 to 2, r is a number from 0 to 1, and they 
have a relation of: p+q+r=2. In order to obtain a particularly high 
activity, r is preferably selected from the range of 0-0.6, and r is an 
important factor for making the molecular distribution sharp. In this 
invention, the effect of giving a sharp molecular weight distribution to 
the resulting polymer with a high activity can be achieved when r is in 
the range of 0.2 to 0.6. 
These organomagnesium compounds can be synthesized by reacting an 
organolithium compound represented by RLi, wherein R has the same meanings 
as R.sup.1 or R.sup.2, with MgZ.sub.2 wherein Z is halogen atom (J. 
Organic Chem. 34 1116-1121 (1969)). The introduction of negative group X 
is carried out by a reaction of organomagnesium compound represented by 
the following formula: 
EQU MgR.sup.1.sub.p R.sup.2.sub.q 
wherein R.sup.1, R.sup.2, p and q are as defined above, with oxygen, 
alcohol, organic acid, ester of organic acid, aldehyde, ketone, silanol, 
siloxane, amine, nitrile, mercaptan or the like. Examples of these 
reagents include ethanol, propanol, butanol, hexanol, octanol, acetic 
acid, propionic acid, butanoic acid, benzoic acid, methyl acetate, butyl 
propionate, acetaldehyde, acetone, methyl ethyl ketone, acetylacetone, 
trimethylsilanol, triphenylsilanol, dimethyldihydrodisiloxane, cyclic 
methylhydrotetrasiloxane, methylhydropolysiloxane, 
phenylhydropolysiloxane, acetonitrile, benzonitrile, methylamine, 
dimethylamine, ethylamine, diethylamine, phenylamine, methyl mercaptan, 
propyl mercaptan, butyl mercaptan and the like. 
Next, as the titanium or vanadium compound (hereinafter referred to as 
component (b)) having at least one halogen atom used for the production of 
solid catalyst (I), halogenides, oxyhalogenides and alkoxyhalogenides of 
titanium and vanadium, such as titanium tetrachloride, titanium 
tetrabromide, titanium tetraiodide, ethoxytitanium trichloride, 
propoxytitanium trichloride, butoxytitanium trichloride, dibutoxytitanium 
dichloride, tributoxytitanium monochloride, vanadium tetrachloride, 
vanadyl trichloride, monobutoxyvanadyl dichloride, dibutoxyvanadyl 
dichloride and the like are used either alone or in the form of mixture. 
Among them, compounds having 3 or more halogen atoms are preferable, and 
titanium tetrachloride is particularly preferable. 
The reaction between organomagnesium compound (a) and titanium or vanadium 
compound (b) is carried out at a temperature up to 150.degree. C., 
preferably at a low temperature of 50.degree. C. or below, in an inert 
reaction medium, for example, an aliphatic hydrocarbon such as hexane or 
heptane, an aromatic hydrocarbon such as benzene, toluene or xylene, or an 
alicyclic hydrocarbon such as cyclohexane or methylcyclohexane. In order 
to obtain a catalyst having a high activity, the molar ratio component 
(a): component (b) in the reaction is recommendably in the range of 
0.05-50, preferably 0.2-10 and particularly preferably 0.5-5. In order to 
achieve a particularly excellent catalytic efficiency, the method of 
simultaneous addition, i.e. the method comprising carrying out the 
reaction while introducing these two catalyst components into the reaction 
zone, is most desirable. 
Though composition and structure of the solid catalyst obtainable by the 
above-mentioned reaction vary in a wide range depending upon the kind of 
starting materials and reaction conditions, they are roughly in the 
following range. That is, molar ratio (Ti+V)/Mg of the solid catalyst is 
in the range of 0.1-5. This solid surface has a very large specific 
surface area. According to a measurement by B. E. T. method, it is as 
great as 50 m.sup.2 /g to 400 m.sup.2 /g. 
As the organic or inorganic aluminum, silicon, tin or antimony compound 
(hereinafter referred to as component (c)), used in the reaction with 
solid catalyst (I) for the purpose of producing solid type catalyst (I') 
those compounds having halogen atom, hydrogen atom, hydrocarbon group, 
alkoxy group or aryloxy group can be mentioned. Examples of such compounds 
include alkoxyaluminum dihalide, alkylaluminum dihalide, monoalkoxysilicon 
halide, monoalkylsilicon halide, silicon tetrahalogenide, monoalkoxytin 
halide, monoalkyltin halide, tin tetrahalogenic, antimony pentachloride, 
monoalkylantimony halide and the like. Among these compounds, 
alkylaluminum dichloride, silicon tetrachloride, and tin tetrachloride are 
particularly preferable. As the titanium or vanadium compound having at 
least one halogen atom (hereinafter referred to as component (d)), the 
same compound (component b)) as used for the synthesis of the solid 
catalyst (I) or other compound belonging to component (b) can be used. 
The reaction with the solid catalyst is carried out by using component (c) 
or component (d) in an amount of 1-50 millimoles and preferably 2-20 
millimoles per 1 g of the solid catalyst, at a temperature ranging from 
room temperature to 150.degree. C. either in an invert hydrocarbon medium 
or in the absence of inert hydrocarbon medium. After completion of the 
reaction, the resulting solid type catalyst is separated, and preferably 
it is washed with an inert hydrocarbon. The reaction of the solid catalyst 
with component (c) or component (d) can be carried out multistage-wise, 
i.e. in two or three steps, by using the same or different compound 
selected from these components. 
Though the solid catalyst or solid type catalyst thus obtained is useful 
even as it is, as a catalyst for olefin polymerization, it is converted to 
a more excellent catalyst by combining it with an organometallic compound 
(II) according to this invention. As said organometallic compound, 
compounds of the elements belonging to Group I-II of the Periodic Table 
are useful, among which organoaluminum compounds and complexes containing 
organomagnesium are particularly preferable. 
As the organoaluminum compounds (II) used in this invention, compounds 
represented by the following formula: 
EQU AlR.sup.3.sub.n Y.sub.3-n 
wherein R.sup.3 is hydrocarbon group having 1-20 carbon atoms, Y is a 
member selected from the group consisting of hydrogen atom, halogen atom, 
alkoxy group, aryloxy group and siloxy group, and n is a number of 2-3, 
can be referred to, and they are used either alone or in the form of a 
mixture. In the formula mentioned above, the hydrocarbon group having 1-20 
carbon atoms represented by R.sup.3 includes aliphatic hydrocarbons, 
aromatic hydrocarbons and alicyclic hydrocarbons. 
Recommendable examples of these compounds include triethylaluminum, 
tri-n-propylaluminum, tri-isopropylaluminum, tri-n-butylaluminum, 
tri-isobutylaluminum, trihexylaluminum, trioctylaluminum, 
tridecylaluminum, tridodecylaluminum, trihexadecylaluminum, 
diethylaluminum hydride, diisobutylaluminum hydride, diethylaluminum 
ethoxide, diisobutylaluminum ethoxide, dioctylaluminum butoxide, 
diisobutylaluminum octyloxide, diethylaluminum chloride, 
diisobutylaluminum chloride, dimethylhydroxyaluminum demethyl, 
ethylmethylhydroxyaluminum diethyl, ethyldimethylsiloxyaluminum diethyl 
and the like and mixtures thereof. 
By combining these alkylaluminum compounds with the above-mentioned solid 
catalyst (I) or solid type catalyst (I') (hereinafter they are sometimes 
collectively represented by "solid catalyst"), a catalyst of high activity 
is obtained. Particularly, trialkylaluminum and dialkylaluminum hydride 
are preferable because they enable to achieve the highest activity. Though 
if a negative group Y is introduced into trialkylaluminum or 
dialkylaluminum hydride their activity tends to drop, the products exhibit 
respective unique polymerization behavior and enable to produce useful 
polymers with a high activity. For example, if an alkoxy group is 
introduced, control of molecular weight becomes easy. As a negative group 
alkoxy group and siloxy group are desirable in that they do not contain 
any halogen. 
The solid catalyst component (I or I') and the organometallic compound (II) 
may be combined together by adding them into the polymerization system 
under the conditions of polymerization or they may be combined together 
beforehand prior to polymerization. Proportion between the two components 
to be combined is preferably in the range of 1-3,000 millimoles of 
organometallic compound per 1 g of the solid catalyst. 
Further, the olefin polymerization catalyst of this invention enables to 
produce a polymer of broad molecular weight distribution with a high 
activity by combining the above-mentioned solid catalyst (I or/and I') and 
organometallic compound (II) with a halogenated hydrocarbon (III). As said 
halogenated hydrocarbon, there are used saturated or unsaturated 
hydrocarbons having 1-10 carbon atoms, and preferably halogenated 
hydrocarbons in which the number of halogen atoms is twice or less the 
number of carbon atoms. Examples of such compound include dichloromethane, 
1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 
1,2-dichloropropane, 1,3-dichloropropane, 1,2,3-trichloropropane, n-butyl 
chloride, isobutyl chloride, 1,4-dichlorobutane, 2,3-dichlorobutane, 
1,2,3,4-tetrachlorobutane, n-hexyl chloride, 1,6-dichlorohexane, 
1,2-dichlorooctane, dibromomethane, 1,2-dibromoethane, n-butyl bromide, 
chlorobenzene, phenethyl chloride, allyl chloride, bromobenzene, ethyl 
iodide and the like. 
The combination of these halogenated hydrocarbon (III), the above-mentioned 
solid catalyst (I and/or I') and the organometallic compound (II) may be 
carried out under the conditions of polymerization with the progress of 
reaction, or these three members may be combined beforehand prior to the 
polymerization. Further, the polymerization may be carried out by once 
reacting the solid catalyst with the halogenated hydrocarbon to isolate 
the solid product, thereafter combining the solid catalyst thus obtained 
with the organometallic compound, and newly adding same or different 
halogenated hydrocarbon or without addition thereof. As for the proportion 
of catalyst components to be reacted, it is desirable that 1-3,000 
millimoles of organometallic compound and 1-3,000 millimiles of 
halogenated hydrocarbon are used per 1 g of solid catalyst and molar ratio 
of organometallic compound to halogenated hydrocarbon is 0.01-100 and 
preferably 0.1-20. 
The olefin which can be polymerized by the use of the catalyst of this 
invention is .alpha.-olefin, and particularly ethylene. Further, the 
catalyst of this invention can also be used for copolymerizing ethylene 
with coexisting monoolefin such as propylene, butene-1, hexene-1 or the 
like or coexisting diene such as butadiene, isoprene or the like or for 
polymerizing propylene with a high efficiency. 
As the process of polymerization, usual suspension polymerization, solution 
polymerization and gaseous polymerization can be employed. In the case of 
suspension polymerization and solution polymerization, the catalyst is 
introduced into a reactor together with a solvent for polymerization such 
as aliphatic hydrocarbon, e.g. hexane or heptane, aromatic hydrocarbon, 
e.g. benzene, toluene or xylene, or alicyclic hydrocarbon, e.g. 
cyclohexane or methylcyclohexane, ethylene is pressed into the reactor up 
to a pressure of 1-200 kg/cm.sup.2 (gage) under an inert atmosphere, and 
the polymerization is set forward at a temperature ranging from room 
temperature to 300.degree. C. On the other hand, the gaseous 
polymerization can be carried out at an ethylene pressure of 1-50 
kg/cm.sup.2 (gage) under a temperature condition of room temperature to 
120.degree. C. by using procedures such as fluidized bed, moving bed or 
mixing with agitator so as to realize a satisfactory contact between 
ehtylene and the catalyst. 
The polymerization may be carried out by the method of one-step 
polymerization using one reaction zone, or it may also be carried out by 
the so-called multi-step method using a plurality of reaction zones. A 
polymer having a broader molecular weight distribution can be produced by 
carrying out the polymerization under two or more different conditions, 
and this technique is quite excellently suitable for the production of a 
product to be molded by blow molding or film molding process. Further, in 
order to control the molecular weight of polymer, it is also possible to 
add hydrogen or an organometallic compound easily causing a chain transfer 
reaction. Furthermore, it is also possible to carry out the polymerization 
in combination with a technique for density control by means of adding a 
titanic acid ester.