Titanium catalyst component for ethylene polymerization, ethylene polymerization catalyst, and process for ethylene polymerization using the same

Disclosed is a titanium catalyst component for ethylene polymerization obtained by contacting [A] a solid magnesium aluminum complex containing magnesium, halogen, aluminum and an alkoxy group and/or alcohol having at least 6 carbon atoms, with [B] a tetravalent titanium compound. The solid magnesium aluminum complex [A] is obtained by contacting (a-1) a magnesium solution formed from a halogen-containing magnesium compound, an alcohol having at least 6 carbon atoms and a hydrocarbon solvent, with (a-2) an organoaluminum compound. Also disclosed is a process for ethylene polymerization comprising polymerizing ethylene or copolymerizing ethylene with an .alpha.-olefin having 3 to 20 carbon atoms in the presence of a catalyst for ethylene polymerization comprising [I] the above-mentioned titanium catalyst component for ethylene polymerization and [II] an organoaluminum compound catalyst component.

FIELD OF THE INVENTION 
The present invention relates to a titanium catalyst component for ethylene 
polymerization by the use of which an ethylene polymer having a narrow 
particle size distribution can be prepared with a high polymerization 
activity, to an ethylene polymerization catalyst comprising the titanium 
catalyst component, and to a process for ethylene polymerization using 
this ethylene polymerization catalyst. 
BACKGROUND OF THE INVENTION 
For preparing ethylene polymers, generally known in the art is a process of 
copolymerizing ethylene with an .alpha.-olefin or polymerizing ethylene in 
the presence of a Ziegler catalyst. In this process, a high-temperature 
solution polymerization wherein polymerization is conducted in a 
hydrocarbon solvent at a temperature higher than the melting point of the 
resultant polymer is broadly utilized. However, if a polymer having a high 
molecular weight is intended to be obtained, a polymer concentration in 
the polymer solution must be lowered because the viscosity of the polymer 
solution becomes high with increase of the molecular weight. As a result, 
a problem of low productivity of a polymer takes place. 
On the other hand, in the case of conducting the polymerization by a slurry 
polymerization process, there resides other problem. That is, the 
resultant polymer swells easily in a polymerization solvent. As a result, 
the concentration of the slurry can be hardly heightened and a long-term 
continuous polymerization operation can be difficultly made. 
The present inventors have studied in the light of the problems associated 
with the prior art as mentioned above, and proposed a titanium catalyst 
component for ethylene polymerization as described in, for example, 
Japanese Patent Laid-Open Publication No. 195108/1985. This titanium 
catalyst component is excellent in handling property as a slurry and makes 
it possible to conduct polymerization operation in a high concentration of 
the slurry. In the titanium catalyst, more than 70% by weight of titanium 
atoms are reduced to trivalent state. By the use of this titanium catalyst 
component, an ethylene polymer having an excellent composition (copolymer) 
distribution can be prepared with a high polymerization activity. 
As described above, by the use of the catalyst component for ethylene 
polymerization disclosed in Japanese Patent Laid-Open Publication No. 
195108/1985, ethylene can be polymerized with a high polymerization 
activity, and moreover, an ethylene copolymer having a narrow composition 
distribution and excellent morphology can be obtained. However, now 
eagerly desired is a titanium catalyst component for ethylene 
polymerization by the use of which an ethylene polymer can be prepared 
with a high polymerization activity. 
Further, Japanese Patent Publication No. 45404/1988 discloses a process for 
the preparation of a solid titanium catalyst component. In this process, 
the solid titanium catalyst component is prepared by contacting a 
magnesium aluminum complex which is obtained by the contact of an alcohol 
solution of halogen-containing magnesium with an organoaluminum compound, 
an electron donor having no active hydrogen and titanium tetrachloride to 
react with each other. The solid titanium catalyst component obtained in 
this process has a good particle size distribution, and hence polyolefin 
obtained by using a catalyst comprising this solid titanium catalyst 
component also has a good particle size distribution. However, the advent 
of a solid titanium catalyst component which has excellent catalytic 
activity for ethylene polymerization has been eagerly desired. 
Furthermore, Japanese Patent Laid-Open Publication No. 159806/1982 
discloses: 
a solid titanium catalyst component prepared by bringing a product obtained 
by reacting a reaction product (a.sub.1) of halogen-containing magnesium 
and an alcohol with an organoaluminum compound into contact with a 
halogen-containing titanium compound, said solid titanium catalyst 
component having a molar ratio of alkoxy group and/or alcohol to titanium 
of not more than 0.25; 
a solid titanium catalyst component prepared by bringing a product obtained 
by reacting a reaction product (a.sub.1) of halogen-containing magnesium 
and an alcohol with an organoaluminum compound into contact with a 
halogen-containing titanium compound and subsequently bringing the 
resulting product into contact with an organoaluminum halide (halogenation 
agent), said solid titanium catalyst component having a molar ratio of 
alkoxy group and/or alcohol to titanium of not more than 0.9; and 
a solid titanium catalyst component obtained by bringing a product prepared 
by reacting a reaction product (a.sub.1) of halogen-containing magnesium 
and an alcohol with an organoaluminum compound into contact with an 
organoaluminum halide (halogenation agent), subsequently bringing the 
resulting product into contact with a halogen-containing titanium compound 
and further bringing the resulting product into contact with an 
organoaluminum halide (halogenation agent), said solid titanium catalyst 
component having a molar ratio of alkoxy group and/or alcohol to titanium 
of not more than 0.9. 
In such solid titanium catalyst components, a molar ratio Ti.sup.3+ 
/Ti.sup.4+ is in the range of 2.0 to 10, and most of the tetravalent 
titanium atoms are reduced into trivalent state. By the use of these 
catalyst components, ethylene can be polymerized with a high 
polymerization activity. However, further desired is the advent of a solid 
titanium catalyst component for ethylene polymerization which has a 
narrower particle size distribution and by the use of which ethylene can 
be polymerized with much higher polymerization activity. 
Moreover, Japanese Patent Laid-Open Publication No. 91106/1992 discloses a 
solid titanium catalyst component obtained by contacting with each other: 
a solid magnesium aluminum complex obtained by contacting a solution formed 
from halogen-containing magnesium, an alcohol and a hydrocarbon solvent 
with organoaluminum, 
a tetravalent compound in a liquid state, and 
a vanadium compound, a zirconium compound or a hafnium compound. 
In the comparative example of the above Japanese Patent Laid-Open 
Publication No. 91106/1992, an experiment wherein 2-ethylhexoxytitanium 
trichloride was used as the tetravalent titanium compound and no vanadium 
compound was used is shown. 
In such solid titanium catalyst component as obtained above, most of 
titanium atoms are reduced into trivalent state, and the catalyst 
component is low in the activity for ethylene polymerization. Accordingly, 
a solid titanium catalyst component having a much higher activity for 
ethylene polymerization is now desired. 
OBJECT OF THE INVENTION 
It is, therefore, an object of the present invention to provide a titanium 
catalyst component for ethylene polymerization by the use of which an 
ethylene polymer having a narrow particle size distribution can be 
prepared with a high polymerization activity, to provide an ethylene 
polymerization catalyst comprising the titanium catalyst component and to 
provide a process for polymerizing ethylene using this titanium catalyst 
component. 
SUMMARY OF THE INVENTION 
The titanium catalyst component for ethylene polymerization according to 
the present invention is a titanium catalyst component for ethylene 
polymerization prepared by contacting: 
[A] a solid magnesium aluminum complex containing magnesium, halogen, 
aluminum and an alkoxy group and/or alcohol having at least 6 carbon 
atoms, said complex being obtained by contacting 
(a-1) a magnesium solution formed from a halogen-containing magnesium 
compound, an alcohol having at least 6 carbon atoms and a hydrocarbon 
solvent, with 
(a-2) an organoaluminum compound; with 
[B] a tetravalent titanium compound, 
wherein titanium atoms contained in the titanium catalyst component are 
substantially tetravalent and a molar ratio of alkoxy group and/or alcohol 
to titanium (OR/Ti) is in the range of 0.26 to 6.0. 
This titanium catalyst component for ethylene polymerization contains, as 
essential components, magnesium, halogen, aluminum, an alkoxy group and/or 
alcohol having at least 6 carbon atoms and titanium. 
A prepolymerized titanium catalyst component [I]' for ethylene 
polymerization according to the present invention is obtained by 
prepolymerizing an olefin to the titanium catalyst component [I] as 
mentioned above. 
The first ethylene polymerization catalyst according to the present 
invention comprises the titanium catalyst component [I] and an 
organoaluminum compound [II]. 
The second ethylene polymerization catalyst according to the present 
invention comprises the prepolymerized titanium catalyst component[I]' and 
an organoaluminum compound [II]. 
The process for ethylene polymerization according to the present invention 
comprises polymerizing ethylene or copolymerizing ethylene with an 
.alpha.-olefin having 3 to 20 carbon atoms in the presence of the ethylene 
polymerization catalyst.

DETAILED DESCRIPTION OF THE INVENTION 
The titanium catalyst component for ethylene polymerization according to 
the present invention, a catalyst for ethylene polymerization containing 
the titanium catalyst component and a process for (co)polymerizing 
ethylene using the titanium catalyst component will be described in detail 
hereinafter. 
The meaning of the term "polymerization" used herein is not limited to 
"homopolymerization" but may comprehend "copolymerization" Also, the 
meaning of the term "polymer" used herein is not limited to "homopolymer" 
but may comprehend "copolymer". 
FIG. 1 is an explanatory view showing one example of a process for 
preparing the titanium catalyst component for ethylene polymerization 
according to the present invention. 
The titanium catalyst component for ethylene polymerization according to 
the present invention is obtained by contacting: 
[A] a solid magnesium aluminum complex containing magnesium, halogen, 
aluminum and an alkoxy group and/or alcohol having at least 6 carbon 
atoms, said complex being obtained by contacting 
(a-1) a magnesium solution formed from a halogen-containing magnesium 
compound, an alcohol having at least 6 carbon atoms and a hydrocarbon 
solvent, with 
(a-2) an organoaluminum compound; with 
[B] a tetravalent titanium compound. 
First, the solid magnesium aluminum complex [A] containing magnesium, 
halogen, aluminum and an alkoxy group and/or alcohol having at least 6 
carbon atoms is described below. 
The solid magnesium aluminum complex [A] is obtained by contacting: 
(a-1) a magnesium solution formed from a halogen-containing magnesium 
compound, an alcohol having at least 6 carbon atoms and a hydrocarbon 
solvent, with 
(a-2) an organoaluminum compound. 
In the solid magnesium aluminum complex [A], the atomic ratio Al/Mg (Al: 
aluminum, Mg: magnesium) is in the range of usually 0.05 to 1, preferably 
0.08 to 0,7, more preferably 0.12 to 0.6. The alkoxy group and/or alcohol 
having at least 6 carbon atoms is contained, based on 1 part by weight of 
magnesium, in an amount of usually 0.5 to 15 parts by weight, preferably 2 
to 13 parts by weight, more preferably 5 to 10 parts by weight. The atomic 
ratio X.sup.1 /Mg (X.sup.1 : halogen) is in the range of usually 1 to 3, 
preferably 1.5 to 2.5. 
The solid magnesium aluminum complex [A] is desired to be particulate, and 
the diameters of the solid magnesium aluminum complex particles are 
preferably in the range of 1 to 200 .mu.m, more preferably 2 to 100 .mu.m. 
With respect to the particle size distribution of the complex [A], the 
geometrical standard deviation is preferably in the range of 1.0 to 2.0, 
particularly preferably 1.0 to 1.8. 
Concrete examples of the halogen-containing magnesium compound for use in 
the preparation of the magnesium solution (a-1) in the invention include: 
magnesium halides, such as magnesium chloride, magnesium bromide, magnesium 
iodide and magnesium fluoride; 
alkoxymagnesium halides, such as methoxymagnesium chloride, ethoxymagnesium 
chloride, isopropoxymagnesium chloride, butoxymagnesium chloride and 
octoxymagnesium chloride; and 
aryloxymagnesium halides, such as phenoxymagnesium chloride and 
methylphenoxymagnesium chloride. 
These compounds may be used as a complex or double compound with another 
metal, or may be used as a mixture with another metallic compound. 
Of these, preferred are magnesium halides and alkoxymagnesium halides; more 
preferred are magnesium chloride and alkoxy magnesium chloride; and most 
preferred is magnesium chloride. 
These compounds may be used singly or in combination. 
The magnesium compound solution (a-1), that is used in a liquid state in 
the invention, is formed from the halogen-containing magnesium compound, 
an alcohol having at least 6 carbon atoms and a hydrocarbon solvent. 
Concrete examples of the alcohol having at least 6 carbon atoms for use in 
the invention include: 
aliphatic alcohols, such as 2-methylpentanol, 2-ethylpentanol, 
2-ethylbutanol, n-heptanol, n-octanol, 2-ethylhexanol, decanol, dodecanol, 
tetradecyl alcohol, undecenol, oleyl alcohol and stearyl alcohol; 
alicyclic alcohols, such as cyclohexanol and methylcyclohexanol; 
aromatic alcohols, such as benzyl alcohol, methylbenzyl alcohol, 
isopropylbenzyl alcohol, .alpha.-methylbenzyl alcohol and 
.alpha.,.alpha.-dimethylbenzyl alcohol; and 
alkoxy group-containing aliphatic alcohols, such as n-butyl cellosolve and 
1-butoxy-2-propanol. 
Preferred are alcohols having at least 7 carbon atoms. Of these, 
2-ethylhexanol is particularly preferred. These alcohols may be used 
singly or in combination. 
When the halogen-containing magnesium compound, the alcohol having at least 
6 carbon atoms and a hydrocarbon solvent are brought into contact with 
each other, the halogen-containing magnesium compound is dissolved in the 
hydrocarbon solvent to give a magnesium solution. 
Concrete examples of the hydrocarbon solvent include: 
aliphatic hydrocarbons, such as propane, butane, n-pentane, isopentane, 
n-hexane, isohexane, n-heptane, n-octane, isooctane, n-decane, n-dodecane 
and kerosine; 
alicyclic hydrocarbons, such as cyclopentane, methylcyclopentane, 
cyclohexane and methylcyclohexane; 
aromatic hydrocarbons, such as benzene, toluene and xylene; and 
halogenated hydrocarbons, such as methylene dichloride, ethyl chloride, 
ethylene dichloride and chlorobenzene. 
Of these, aliphatic hydrocarbons, particularly those of 3 to 10 carbon 
atoms, are preferably employed. 
These hydrocarbon solvents may be used singly or in combination. 
The contact of the halogen-containing magnesium compound, the alcohol 
having at least 6 carbon atoms and the hydrocarbon solvent with each other 
is carried out at a temperature of usually not lower than room 
temperature, preferably not lower than 65.degree. C., more preferably 
about 80.degree. to 300.degree. C., most preferably about 100.degree. to 
about 200.degree. C., for a period of 15 minutes to 5 hours, preferably 30 
minutes to 3 hours, though these conditions vary depending upon the 
compound and the alcohol used, etc. 
The alcohol is used in an amount of generally not less than 1 mol, 
preferably about 1.5 to about 20 mol, more preferably about 2.0 to about 
12 mole, per 1 mol of the halogen-containing magnesium compound, though 
this amount varies depending upon the magnesium compound and the solvent 
used, etc. 
By contacting the magnesium solution (a-1) with an organoaluminum compound 
(a-2), a solid magnesium aluminum complex [A] is obtained. 
Preferably used as the organoaluminum compound (a-2) in the invention is, 
for example, an organoaluminum compound represented by the following 
formula (iv): 
EQU R.sup.a.sub.n AlX.sub.3-n (iv) 
wherein R.sup.a is a hydrocarbon group of 1 to 12 carbon atoms, X is a 
halogen atom or hydrogen, and n is 1 to 3. 
The hydrocarbon group of 1 to 12 carbon atoms includes an alkyl group, a 
cycloalkyl group and an aryl group. Examples of such groups include 
methyl, ethyl, n-propyl, isopropyl, isobutyl, pentyl, hexyl, octyl, 
cyclopentyl, cyclohexyl, phenyl and tolyl. 
Concrete examples of such organoaluminum compound (a-2) include: 
trialkylaluminums, such as trimethylaluminum, triethylaluminum, 
triisopropylaluminum, triisobutylaluminum, trioctylaluminum and 
tri-2-ethylhexylaluminum; 
alkenylaluminums, such as isoprenylaluminum; 
dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum 
chloride, diisopropylaluminum chloride, diisobutylaluminum chloride and 
dimethylaluminum bromide; 
alkylaluminum sesquihalides, such as methylaluminum sesquichloride, 
ethylaluminum sesquichloride, isopropylaluminum sesquichloride, 
butylaluminum sesquichloride and ethylaluminum sesquibromide; 
alkylaluminum dihalides, such as methylaluminum dichloride, ethylaluminum 
dichloride, isopropylaluminum dichloride and ethylaluminum dibromide; and 
alkylaluminum hydrides, such as diethylaluminum hydride and 
diisobutylaluminum hydride. 
Also employable as the organoaluminum compound is a compound represented by 
the following formula (v): 
EQU R.sup.a.sub.n AlY.sub.3-n (v) 
wherein R.sup.a is the same as R.sup.a in the above formula (iv); n is 1 or 
2; and Y is --OR.sup.b, --OSiR.sup.c.sub.3, --OAlR.sup.d.sub.2, 
--NR.sup.e.sub.2, --SiR.sup.f.sub.3 or --N(R.sup.g)AlR.sup.h.sub.2 
(wherein R.sup.b, R.sup.c, R.sup.d and R.sup.h are each methyl, ethyl, 
isopropyl, isobutyl, cyclohexyl or phenyl; R.sup.e is hydrogen, methyl, 
ethyl, isopropyl, phenyl or trimethylsilyl; and R.sup.f and R.sup.g are 
each methyl or ethyl). 
Concrete examples of such organoaluminum compounds include: 
(1) compounds of the formula R.sup.a.sub.n Al(OR.sup.b).sub.3-n, such as 
dimethylaluminum methoxide, diethylaluminum ethoxide and 
diisobutylaluminum methoxide; 
(2) compounds of the formula R.sup.a.sub.n Al(OSiR.sup.c.sub.3).sub.3-n, 
such as Et.sub.2 Al(OSiMe.sub.3), (iso-Bu).sub.2 Al(OSiMe.sub.3) and 
(iso-Bu).sub.2 Al(OSiEt.sub.3); 
(3) compounds of the formula R.sup.a.sub.n Al(OAlR.sup.d.sub.2).sub.3-n, 
such as Et.sub.2 AlOAlEt.sub.2 and (iso-Bu).sub.2 AlOAl(iso-Bu).sub.2 ; 
(4) compounds of the formula R.sup.a.sub.n Al(NR.sup.e.sub.2).sub.3-n, such 
as Me.sub.2 AlNEt.sub.2, Et.sub.2 AlNHMe, Me.sub.2 AlNHEt, Et.sub.2 
AlN(Me.sub.3 Si).sub.2 and (iso-Bu).sub.2 AlN(Me.sub.3 Si).sub.2 ; 
(5) compounds of the formula R.sup.a.sub.n Al(SiR.sup.f.sub.3).sub.3-n, 
such as (iso-Bu).sub.2 AlSiMe.sub.3 ; and 
(6) compounds of the formula R.sup.a.sub.n Al[N(R.sup.g)AlR.sup.h.sub.2 
].sub.3-n, such as Et.sub.2 AlN(Me)AlEt.sub.2 and (iso-Bu).sub.2 
AlN(Et)Al(iso-Bu).sub.2. 
In addition, also employable as the the organoaluminum compound (a-2) is a 
complex alkylate which is formed from a metal of Group I of the periodic 
table and aluminum, said complex alkylate being represented by the 
following formula: 
EQU M.sup.1 AlR.sup.j.sub.4 
wherein M.sup.1 is Li, Na or K, and R.sup.j is a hydrocarbon group of 1 to 
15 carbon atoms. 
Concrete examples of such complex alkylate include LiAl(C.sub.2 
H.sub.5).sub.4 and LiAl(C.sub.7 H.sub.15).sub.4. 
Of the organoaluminum compounds as exemplified above, preferably used are 
trialkylaluminum, dialkylaluminum halide, dialkylaluminum hydride and 
dialkylaluminum alkoxide. Of these, trialkylaluminum, particularly 
triethylaluminum, is preferred because a catalyst with a favorable shape 
can be obtained by using it. 
These organoaluminum compounds may be used alone or in combination. 
For forming the solid magnesium aluminum complex [A], the organoaluminum 
compound (a-2) is desirably used in such an amount that the molar ratio 
(ROH/Al) of the alcohol (ROH) having at least 6 carbon atoms used for the 
preparation of the magnesium solution (a-1) to the aluminum atom (Al) 
contained in the organoaluminum compound (a-2) is in the range of about 
0.5 to 7, preferably 1 to 5. 
The contact of the magnesium solution (a-1) with the organoaluminum 
compound (a-2) can be carried out by dropwise adding the organoaluminum 
compound (a-2) slowly to the magnesium solution (a-1) having a magnesium 
concentration of preferably 0.005 to 2 mol/l, more preferably 0.05 to 1 
mol/l, with stirring of the magnesium solution. In this manner, a solid 
magnesium aluminum complex [A] having excellent particle properties 
(excellent morphology) can be obtained. 
The temperature for contacting the magnesium solution (a-1) with the 
organoaluminum compound (a-2) is in the range of usually -50.degree. to 
150 .degree. C., preferably -30.degree. to 100.degree. C. 
The solid magnesium aluminum complex [A] thus obtained contains no reducing 
organic group, and hence it exhibits no reduction ability. 
The titanium catalyst component for ethylene polymerization [I] according 
to the present invention is obtained by contacting the above-described 
solid magnesium aluminum complex [A] with a tetravalent compound [B]. 
Preferably used as the tetravalent titanium compound [B] is a compound 
represented by the following formula (ii): 
EQU Ti(OR.sup.2).sub.g X.sub.4-g (ii) 
wherein R is a hydrocarbon group, X is a halogen atom, and 0&lt;g&lt;3. 
Concrete examples of such titanium tetravalent compound [B] include: 
titanium tetrahalides, such as TiCl.sub.4, TiBr.sub.4 and TiI.sub.4 ; 
alkoxytitanium trihalides, such as 
Ti (OCH.sub.3)Cl.sub.3, 
Ti (OC.sub.2 H.sub.5)Cl.sub.3, 
Ti (On-C.sub.4 H.sub.9)Cl.sub.3, 
Ti (OC.sub.2 H.sub.5)Br.sub.3, and 
Ti (O-iso-C.sub.4 H.sub.9)Br.sub.3 ; 
dialkoxytitanium dihalides, such as 
Ti (OCH.sub.3).sub.2 Cl.sub.2, 
Ti (OC.sub.2 H.sub.5).sub.2 Cl.sub.2, 
Ti (On-C.sub.4 H.sub.9).sub.2 Cl.sub.2, and 
Ti (OC.sub.2 H.sub.5).sub.2 Br.sub.2 ; and 
trialkoxytitanium monohalides, such as 
Ti (OCH.sub.3).sub.3 Cl, 
Ti (OC.sub.2 H.sub.5).sub.3 Cl, 
Ti (On-C.sub.4 H.sub.9).sub.3 Cl, and 
Ti ((OC.sub.2 H.sub.5).sub.3 Br. 
Of these, preferably used are titanium tetrahalides and particularly 
preferred is titanium tetrachloride. 
These compounds may be used singly or in combination. 
The tetravalent titanium compound [B] is used in such an amount that the 
atomic ratio (Ti/(Mg+Al)) of the titanium (Ti) contained in the compound 
[B] to the magnesium and the aluminum contained in the solid magnesium 
aluminum complex [A] is in the range of 0.005 to 18, preferably 0.01 to 
15. 
The contact of the solid magnesium aluminum complex [A] with the 
tetravalent titanium compound [B] is carried out preferably in a 
hydrocarbon solvent. As the hydrocarbon solvent, those similar to the 
aforesaid hydrocarbons can be employed. 
In the invention, the contact is carried out at a temperature of usually 
0.degree. to 150.degree. C., preferably 50.degree. to 130.degree. C., more 
preferably 50.degree. to 120.degree. C. 
The titanium catalyst component for ethylene polymerization according to 
the invention can be obtained in the manner as described above, and it 
contains, as essential components, magnesium, halogen, aluminum, an alkoxy 
group and/or alcohol having at least 6 carbon atoms and titanium. The 
titanium contained in this titanium catalyst component is substantially in 
a tetravalent state, namely more than 90%, preferably more than 95%, most 
preferably 100% of titanium atoms are in the tetravalent state. 
The atomic ratio Ti/Mg of the titanium catalyst component is in the range 
of usually 0.01 to 1.5, preferably 0.05 to 1.0. 
The atomic ratio Al Mg of the titanium catalyst component is in the range 
of usually 0.1 to 2.0, preferably 0.13 to 1.5, most preferably 0.15 to 
1.2. 
The molar ratio of alkoxy group and/or alcohol to titanium (OR)/Ti of the 
titanium catalyst component is in the range of 0.26 to 6.0, preferably 
0.26 to 5.0, most preferably 0.26 to 4.0. 
The amount of the alkoxy group and/or alcohol having at least 6 carbon 
atoms is in the range of usually 0.1 to 15 parts by weight, preferably 0.3 
to 10 parts by weight, more preferably 0.5 to 6 parts by weight, based on 
1 part by weight of magnesium. 
The titanium catalyst component is preferably in the form of particles, and 
the particle diameter thereof is preferably in the range of 1 to 200 
.mu.m, more preferably 2 to 100 .mu.m. The geometrical standard deviation 
of the titanium catalyst component particles in the particle size 
distribution is in the range of 1.0 to 2.0, preferably 1.0 to 1.8. 
The prepolymerized titanium catalyst component [I]' for ethylene 
polymerization according to the present invention is obtained by 
prepolymerizing an olefin to a catalyst comprising [I] the titanium 
catalyst component as mentioned above and [II] an organoaluminum compound 
as mentioned above. 
The olefins to be polymerized to the titanium catalyst component [I] 
include ethylene and .alpha.-olefin having 3-20 carbon atoms 
aforementioned. 
Of these, preferably ethylene is prepolymerized or ethylene and 
.alpha.-olefin having 3-20 carbon atoms or ethylene are prepolymerized. 
The catalyst for ethylene polymerization according to the present invention 
comprises 
[I] the titanium catalyst component for ethylene polymerization as 
mentioned above, and 
[II] the organoaluminum compound as mentioned above. 
The another catalyst for ethylene polymerization according to the present 
invention comprises 
[I]' the prepolymerized titanium catalyst component as mentioned above, and 
[II] the organoaluminum compound as mentioned above. 
In accordance with the process for ethylene polymerization according to the 
present invention, ethylene is polymerized or copolymerized with an 
.alpha.-olefin having 3 to 20 carbon atoms in the presence of a catalyst 
for ethylene polymerization formed from [I] the above-described titanium 
catalyst for ethylene polymerization and [II] an organoaluminum compound 
catalyst component. 
Examples of the .alpha.-olefins having 3 to 20 carbon atoms to be 
copolymerized with ethylene includes propylene, 2-methylpropylene, 
1-butene, 1-hexene, 1-pentene, 4-methyl-1pentene, 3-methyl-1-pentene, 
1-octene, 1-nonene, 1-decene, 1-undecene and 1-dodecene. The 
.alpha.-olefins may be copolymerized with polyenes. Examples of such 
polyenes include butadiene, isoprene, 1,4-hexadiene, dicyclopentadiene and 
5-ethylidene-2-norbornene. 
The copolymer of ethylene with the .alpha.-olefin thus obtained contains 
constituent units derived from ethylene preferably in an amount of at 
least 90% by mol. 
As the organoaluminum compound [II] for use in the polymerization, the 
aforesaid organoaluminum compound (a-2) used in the preparation of the 
titanium catalyst component for ethylene polymerization [I] can be 
employed. 
In the polymerization, the titanium catalyst component for ethylene 
polymerization [I] is used in an amount of generally about 0.00001 to 
about 1 mmol, preferably about 0.0001 to about 0.1 mmol, in terms of Ti 
atom, per 1 liter of the polymerization reaction volume. 
The organoaluminum compound [II] is used in an amount of 1 to 1,000 mol, 
preferably 2 to 500 mol, per 1 g.atom of the titanium contained in the 
titanium catalyst component for ethylene polymerization [I], according to 
necessity. 
The titanium catalyst component for ethylene polymerization may be 
supported on a carrier. Examples of such a carrier include Al.sub.2 
O.sub.3, SiO.sub.2, B.sub.2 O.sub.3, MgO, CaO, TiO.sub.2, ZnO, Zn.sub.2 O, 
SnO.sub.2, BaO, ThO and resins such as a styrene/divinylbenzene copolymer. 
Further, the catalyst for ethylene polymerization as described above may be 
prepolymerized with ethylene. 
Hydrogen may be used in the polymerization stage, whereby a molecular 
weight of a polymer to be obtained can be regulated. 
In the present invention, the polymerization of ethylene may be carried out 
by either a liquid phase polymerization, such as a solution polymerization 
and a suspension polymerization, or a gas phase polymerization Further, 
the polymerization may be carried out either batchwise, semi-continuously 
or continuously. 
When a slurry polymerization is carried out, any of an inert solvent and 
ethylene which is liquid at a polymerization temperature may be used as a 
reaction solvent. 
Examples of such inert solvents include aliphatic hydrocarbons, such as 
propane, butane, n-pentane, isopentane, n-hexane, isohexane, n-heptane, 
n-octane, isooctane, n-decane, n-dodecane and kerosine; alicyclic 
hydrocarbons, such as cyclopentane, methylcyclopentane, cyclohexane and 
methylcyclohexane; and aromatic hydrocarbons, such as benzene, toluene, 
xylene and ethylbenzene. These inert solvents may be used singly of in 
combination. 
The polymerization temperature is in the range of usually 20.degree. to 
150.degree. C., preferably 50.degree. to 120.degree. C., more preferably 
70.degree. to 110.degree. C.; and the polymerization pressure is in the 
range of usually 1 to 1,000 kg/cm.sup.2, preferably 2 to 40 kg/cm.sup.2. 
The copolymerization may be carried out in plural steps. 
The ethylene polymer obtained as above may be either a homopolymer of 
ethylene, an ethylene/.alpha.-olefin random copolymer or a block 
copolymer, but preferred are a homopolymer of ethylene and a random 
copolymer of ethylene with an .alpha.-olefin. 
Particularly preferably, an ethylene homopolymer or an 
ethylene/.alpha.-olefin copolymer, having a density of 0.900 to 0 970 
g/cm.sup.3 preferably 0.910 to 0.970 g/cm.sup.3, is prepared in the 
present invention. The density used herein is that determined in 
accordance with ASTM D1505. 
According to the present invention as described above, ethylene can be 
(co)polymerized with a high polymerization activity, and moreover, 
ethylene can be copolymerized with an .alpha.-olefin of 3 to 20 carbon 
atoms. 
In the invention, the ethylene (co)polymer is obtained in the form of 
particles, and the particle diameter is in the range of generally 10 to 
1,500 .mu.m, preferably 10 to 1,000 .mu.m. 
The geometrical standard deviation of the particles is in the range of 1.0 
to 2.0, preferably 1.0 to 1.8. 
The ethylene (co)polymer obtained as above according to the present 
invention has a narrow particle size distribution. 
In the powdery (co)polymer of the present invention, it is desired that the 
particles having a diameter of not smaller than 850 .mu.m are contained in 
an amount of not more than 1.0% by weight, preferably not more than 0.8% 
by weight, particularly preferably not more than 0.5% by weight; the 
particles having a diameter of not larger than 100 .mu.m are contained in 
an amount of not more 7.0% by weight, preferably not more than 5.0% by 
weight, particularly preferably not more than 3.0% by weight; and the 
particles having a diameter of 100 to 500 .mu.m are contained in an amount 
of not less than 85% by weight, preferably not less than 90% by weight; 
each being based on the total weight of the particles. 
The ethylene (co)polymer obtained in the invention may contain various 
additives, such as heat stabilizers, weathering stabilizers, antistatic 
agents, anti-blocking agents, lubricants, nucleating agents, pigments, 
dyes, inorganic fillers and organic fillers. 
EFFECT OF THE INVENTION 
In the titanium catalyst component for ethylene polymerization according to 
the present invention, the halogen-containing titanium compound is 
supported on the solid magnesium aluminum complex, and the titanium 
contained in this catalyst component is in a tetravalent state. Hence, use 
of the titanium catalyst component makes it possible to polymerize 
ethylene with a high polymerization activity, and moreover, when ethylene 
is copolymerized with an .alpha.-olefin of 3 to 20 carbon atoms, an 
ethylene copolymer having a narrow particle size distribution can be 
prepared. 
Specifically, by the use of the titanium catalyst component for ethylene 
polymerization, ethylene (co)polymer particles having a narrow particle 
size distribution can be obtained, and extremely small sized particles are 
produced in only a small amount. 
The process for ethylene (co)polymerization according to the present 
invention is carried out using such titanium catalyst component for 
ethylene polymerization as described above to provide an ethylene 
(co)polymer having a narrow particle size distribution and excellent 
morphology with a high polymerization activity. When the polymerization is 
carried out in a slurry polymerization, a slurry-handling property is also 
excellent. 
EXAMPLE 
The present invention will be described below in more detail with reference 
to examples, but it should be construed that the invention is in no way 
limited to those examples. 
Analysis of the catalyst for ethylene polymerization and measurements of 
the particle size distribution and further the geometrical standard 
deviation are carried out in the following manner. 
1. Mg, Al, Ti 
Content determination of Mg, Al and Ti was carried out by ICP analysis 
using an analyzer (ICPF1000TR, produced by Shimazu Seisakusho K. K.). 
2. Cl 
Content determination of Cl was carried out by a silver nitrate titration 
method. 
3. OR group 
Content determination of OR group (or alcohol) was carried out as follows. 
A well dried catalyst was added to an acetone solution containing 10% by 
weight of water to undergo hydrolysis so as to obtain ROH, and the ROH was 
determined by means of gas chromatography. 
4. Particle size distribution and geometrical standard deviation 
The particle size distribution and the geometrical standard deviation were 
measured by the use of a vibrator (low-tap type, produced by Iida 
Seisakusho K.K.) and a sieve (Iida lasting sieve of JIS-Z-8801, inner 
diameter: 200 mm). 
EXAMPLE 1 
[Preparation of a catalyst component] 
4.8 g of a commercially available magnesium chloride anhydride, 19.5 g of 
2-ethylhexanol and 200 ml of decane were heated at 140.degree. C. for 3 
hours to give a homogeneous solution containing the magnesium chloride. To 
the solution, a mixture solution composed of 60 mmol of triethylaluminum 
and 52 ml of decane was dropwise added at 20.degree. C. over 30 minutes 
while stirring. Then, the temperature of the resulting mixture was 
elevated to 80.degree. C. over 2 hours and heated at the same temperature 
for 2 hours. After completion of the reaction under heating, a solid 
portion was separated by filtration and washed once with 200 ml of decane, 
to obtain a solid magnesium aluminum complex. 
The solid magnesium aluminum complex thus obtained was suspended again in 
200 ml of decane, and to the resulting suspension was added 400 mmol of 
titanium tetrachloride to perform reaction at 80.degree. C. for 2 hours. 
Then, the reaction product was well washed with hexane to obtain a hexane 
suspension of a solid catalyst. The composition of the solid catalyst is 
set forth in Table 2. 
A portion (corresponding to 5 g of the solid catalyst) of the hexane 
suspension of the solid catalyst was withdrawn and this portion was 
introduced into a 300 ml reactor equipped with a Teflon stirrer. To the 
reactor was further added 0.5 g of liquid paraffin, and the content of the 
reactor was stirred. Then, the reactor was placed in a bath of 40.degree. 
C. while causing nitrogen to pass through the reactor at a rate of 80 
Nl/Hr, to evaporate hexane. By the evaporation, a powdery Ti catalyst 
component containing about 10% of liquid paraffin was obtained. 
[Polymerization] 
A 2-liter autoclave was charged with 1 liter of purified hexane in a 
nitrogen atmosphere. Then, 1.0 mmol of triethylaluminum and the powdery Ti 
catalyst component obtained in the above were suspended in hexane, and 0.1 
mmol (in terms of Ti atom) of the resulting suspension was added to the 
polymerizer. The temperature of the system was elevated to 80.degree. C., 
and to the polymerizer was fed 4.0 kg/cm.sup.2 G of hydrogen and was then 
further fed ethylene continuously over 2 hours so that the total pressure 
was kept at 8.0 kg/cm.sup.2 G. The temperature during the polymerization 
was kept at 80.degree. C. 
After the polymerization was completed, an ethylene polymer produced was 
separated from the hexane solvent and dried. 
The results of measurements on the properties of the ethylene polymer are 
set forth in Table 3. 
The yield of the powdery polymer obtained was 227 g, and the polymer had 
MFR of 2.7 g/10 min and an apparent bulk specific gravity of 0.33 g/cc. 
The particle size distribution of the powdery polymer is set forth in Table 
1. 
TABLE 1 
______________________________________ 
&gt;850 850 500 .mu.m 
250 .mu.m 
180 .mu.m 
100 .mu.m 
&gt;45 
.mu.m .mu.m .about. .about. 
.about. 
.about. 
.mu.m 
.about. 250 .mu.m 
180 .mu.m 
100 .mu.m 
45 .mu.m 
500 .mu.m 
0 0.4 93.1 4.1 1.8 0.6 0 
wt. % wt. % wt. % wt. % wt. % 
______________________________________ 
EXAMPLE 2 
Preparation of a catalyst component and polymerization were carried out in 
a manner similar to that of Example 1 except for varying the amount of 
2-ethylhexanol from 19.5 g to 16.3 g and the amount of triethylaluminum 
from 60 mmol to 46 mmol. 
The results of measurements on the properties of the polymer obtained are 
set forth in Table 3. 
EXAMPLE 3 
Preparation of a catalyst component and polymerization 5 were carried out 
in a manner similar to that of Example 2 except for varying the 
temperature condition after addition of 400 mmol of titanium tetrachloride 
from 80.degree. C. to 100.degree. C. 
The results of measurements on the properties of the polymer obtained are 
set forth in Table 3. 
EXAMPLE 4 
Preparation of a catalyst component and polymerization were carried out in 
a manner similar to that of Example 1 except for varying the amount of 
2-ethylhexanol from 19.5 g to 16.3 g and the amount of triethylaluminum 
from 60 mmol to 43 mmol. 
The results of measurements on the properties of the polymer obtained are 
set forth in Table 3. 
EXAMPLE 5 
Preparation of a catalyst component and polymerization were carried out in 
a manner similar to that of Example 1 except for varying the amount of 
2-ethylhexanol from 19.5 g to 15.3 g and the amount of triethylaluminum 
from 60 mmol to 41 mmol. 
The results of measurements on the properties of the polymer obtained are 
set forth in Table 3. 
COMATIVE EXAMPLE 1 
4.8 g of a commercially available magnesium chloride anhydride, 19.5 g of 
2-ethylhexanol and 200 ml of decane were heated at 140.degree. C. for 3 
hours to give a homogeneous solution containing magnesium chloride. To the 
solution, a mixture solution composed of 52 mmol of triethylaluminum and 
45 ml of decane was dropwise added at 20.degree. C. over 30 minutes while 
stirring. Then, the temperature of the resulting mixture was elevated to 
80.degree. C. over 2.5 hours and heated at 80.degree. C. for 1 hour. After 
completion of the reaction under heating, the reaction slurry was allowed 
to stand, then the supernatant was removed, and to the remaining slurry 
containing a solid portion produced in the above reaction were added 200 
ml of decane and 50 mmol of diethylaluminum chloride to perform reaction 
again at 80.degree. C. for 1 hour. Subsequently, the solid portion was 
separated by filtration and washed once with 100 ml of decane, to prepare 
a solid component containing an organic group having reduction ability. 
The solid component thus obtained was suspended again in 200 ml of decane, 
and to the resulting suspension was then added 25 mmol of titanium 
tetrachloride to perform reaction at 80.degree. C. for 2 hours. 
Thereafter, a solid produced by the reaction was separated by filtration 
and washed 5 times with hexane, to obtain a titanium catalyst component. 
Using the titanium catalyst component thus obtained, ethylene was 
polymerized in a manner similar to that of Example 1. 
The results of measurements on the properties of the polymer obtained are 
set forth in Table 3. 
TABLE 2 
______________________________________ 
Molar 
Composition of the solid catalyst 
ratio 
(wt. %) of 
Ti.sup.4 
Ti.sup.3+ /Ti.sup.4+ 
Mg Al Cl OR OR/Ti 
______________________________________ 
Ex. 1 7.3 0 8.8 5.0 53 10.5 0.53 
Ex. 2 7.0 0 10.2 4.7 50 12.8 0.67 
Ex. 3 7.0 0 8.6 4.0 60 5.3 0.28 
Ex. 4 6.7 0 9.2 4.4 53 11.4 0.63 
Ex. 5 6.7 0 9.8 4.6 50 12.9 0.71 
Comp. Ex. 1 5.7 12.0 0.7 43 34 2.20 
______________________________________ 
Remark 
OR: alkoxy group and/or alcohol 
TABLE 3 
__________________________________________________________________________ 
Particle Size 
Distribution 
Bulk (wt. %) Geometri- 
Activity Specific 100 .mu.m 
cal 
g-PE/g- MFR Gravity .about. Standard 
catalyst g/10 min 
g/cc &gt;500 .mu.m 
500 .mu.m 
.ltoreq.100 .mu.m 
Deviation 
__________________________________________________________________________ 
Ex. 1 
34,600 
2.7 0.33 0.4 99.0 
0.6 1.56 
Ex. 2 
36,900 
4.4 0.32 0 98.9 
1.1 1.51 
Ex. 3 
33,000 
4.9 0.31 0.7 98.0 
1.5 1.60 
Ex. 4 
31,200 
5.7 0.30 0.3 98.8 
0.8 1.64 
Ex. 5 
33,900 
4.5 0.30 0.2 98.2 
1.6 1.54 
Comp. 
10,600 
2.8 0.30 1.1 98.1 
0.9 1.54 
Ex. 1 
__________________________________________________________________________ 
COMATIVE EXAMPLE 2 
[Catalyst] 
30 mmol of a commercially available magnesium chloride anhydride was 
suspended in 150 ml of n-decane. To the resultant suspension was dropwise 
added 120 mmol of n-butanol over 1 hour with stirring of the suspension, 
to perform reaction at 80.degree. C. for 3 hours. Then, to the suspension 
was further dropwise added 240 mmol of diethylaluminum monochloride at 
room temperature to perform reaction at 90.degree. C. for 3 hours. The 
solid portion obtained in the reaction was washed and then suspended in 
n-decane to give a n-decane suspension. To the suspension was dropwise 
added 3 mmol of titanium tetrachloride to perform reaction at 25.degree. 
C. for 10 minutes. 
The composition of catalyst thus obtained is set forth in Table 4. 
[Polymerization] 
A stainless autoclave with a content volume of 2 liters was thoroughly 
purged with nitrogen, then charged with 1 liter of n-hexane and heated to 
50.degree. C. Thereafter, to the autoclave were added 1.0 mmol of 
triisobutylaluminum, 0.5 mmol of ethylene dichloride and 0.02 mmol (in 
terms of Ti atom) of the catalyst obtained in the above. After sealing of 
the autoclave, to the autoclave were fed hydrogen so that the gauge 
pressure was 4.5 kg/cm.sup.3 and then further fed ethylene so that the 
gauge pressure was 8 kg/cm.sup.3. The reaction system was kept at 
80.degree. C. for 2 hours while continuously feeding ethylene to the 
autoclave to keep the total pressure at 8 kg/cm.sup.3 -G. 
The yield of polyethylene thus obtained was 316 g. This amount corresponds 
to a polymerization activity of 16,800 g-PE/g-catalyst. 
TABLE 4 
______________________________________ 
Molar 
Composition of the solid catalyst 
ratio 
(wt. %) of 
Ti.sup.3+ 
Ti.sup.4+ 
Ti.sup.3+ /Ti.sup.4+ 
Mg Al Cl OR OR/Ti 
______________________________________ 
Comp. 3.6 1.5 2.4 17 4.2 70 1.4 0.10 
Ex. 2 
______________________________________ 
EXAMPLE 6 
[Prepolymerization] 
A 400 ml cylindrical flask equipped with a stirrer was charged with 200 ml 
of purified hexane, 6 mmol of triethylaluminum and 2 mmol (in terms of Ti 
atom) of a hexane suspension of the powdery titanium catalyst component 
obtained in Example 1. Thereafter, to the flask was fed ethylene at a feed 
rate of 1.74 Nl/hour over 3 hours at 20.degree. C. to perform 
prepolymerization of the catalyst component with ethylene. The amount of 
polyethylene produced was 5 g based on 1 g of the catalyst. 
[Polymerization] 
A 2-liter autoclave was charged with 1 liter of purified hexane in a 
nitrogen atmosphere. To the autoclave were then added 1.0 mmol of 
triethylaluminum and 0.01 mmol (in terms of Ti atom) of the catalyst 
component having been subjected to the prepolymerization in the above 
stage, and the temperature of the system was elevated to 80.degree. C. 
Thereafter, to the autoclave was fed hydrogen so that the pressure in the 
system was 4.0 kg/cm.sup.2 -G, and was further fed ethylene continuously 
for 2 hours so that the total pressure was 8.0 kg/cm.sup.2 -G. The 
temperature during the polymerization stage was kept at 80.degree. C. 
After the polymerization was completed, an ethylene polymer produced was 
separated from the hexane solvent and dried. 
The results of measurement on the properties of the polymer are set forth 
in Table 5. 
TABLE 5 
______________________________________ 
Activ- Bulk Particle Size 
ity Specif- Distribution 
g-PE/ MFR ic 100 .mu.m 
g-cata- g/10 Gravity .about. 
lyst min g/cc &gt;500 .mu.m 
500 .mu.m 
.ltoreq.100 .mu.m 
______________________________________ 
Ex. 6 
32,800 2.3 0.34 0.6 98.5 0.9 
______________________________________ 
COMATIVE EXAMPLE 3 
In a 400 ml four-neck flask, 30 mmol of magnesium chloride anhydride was 
suspended in 150 ml of n-decane. To the resultant suspension was dropwise 
added 180 mmol of ethanol over 1 hour with stirring of the suspension, to 
perform reaction at room temperature for 1 hour. Through the reaction, a 
white powder was obtained from a swollen magnesium chloride. Then, to the 
reaction system was dropwise added 84 mmol of diethylaluminum monochloride 
at room temperature to perform reaction at 30.degree. C. for 1 hour. 
Thereafter, 300 mmol of titanium tetrachloride was added to the reaction 
system, and the temperature of the system was elevated to 80.degree. C. to 
perform reaction for 3 hours while stirring the reaction solution. After 
the reaction was completed, a solid portion was separated from the 
solution, and the solid portion was washed with 2 liters of n-decane. 
[Polymerization] 
A 2-liter stainless steel autoclave was thoroughly purged with nitrogen. 
Then, the autoclave was charged with 1 liter of n-hexane and was heated to 
50.degree. C. To the autoclave were added 1.0 mmol of triisobutylaluminum, 
0.5 mmol of ethylene dichloride and 0.02 mmol (in terms of Ti atom) of the 
catalyst obtained in the above, and the autoclave was sealed. Thereafter, 
into the autoclave was pressed hydrogen until the gauge pressure became 
4.5 kg/cm.sup.2, and was further pressed ethylene until the gauge pressure 
became 8 kg/cm.sup.2. Then, to the autoclave was continuously fed ethylene 
at 80.degree. C. for 2 hours so that the total pressure was kept at 8 
kg/cm.sup.2 -G. 
The results of measurements on the properties of the polymer obtained are 
set forth in Table 6. 
TABLE 6 
__________________________________________________________________________ 
Particle Size 
Distribution 
Bulk (wt. %) Geo- 
Activity Specific 100 .mu.m metrical 
g-PE/g- 
MFR Gravity .about. Standard 
catalyst 
g/10 min 
g/cc &gt;500 .mu.m 
500 .mu.m 
.ltoreq.100 .mu.m 
Deviation 
__________________________________________________________________________ 
Comp. 
36,600 
3.0 0.31 17.6 65.8 16.5 2.29 
Ex. 3 
__________________________________________________________________________