Ethylene copolymers

A copolymer consisting essentially of ethylene and an .alpha.-olefin with 5 to 18 carbon atoms, said copolymer having PA0 (i) a density of 0.90 to 0.94 g/cm.sup.3, PA0 (ii) an intrinsic viscosity [.eta.] of 0.8 to 4.0 dl/g, PA0 (iii) a maximum melting point, determined by differential thermal analysis, of 115.degree. to 130.degree. C., and PA0 (iv) a g.sub..eta. *(=[.eta.]/[.eta.].sub.l) value of 0.05 to 0.78, in which formula [.eta.] is the intrinsic viscosity of the copolymer and [.eta.].sub.l is the intrinsic viscosity of a linear polyethylene having the same weight average molecular weight determined by the light scattering method as said copolymer.

This invention relates to ethylene copolymers having unique structural 
characteristics not described in the literature and superior moldability, 
and to their melt-shaped articles such as films or sheets having superior 
transparency, improved tear resistance and improved impact resistance. The 
ethylene copolymers of this invention have superior improved properties 
eliminating the unsatisfactory levels of the various properties, such as 
tear resistance, impact strength and transparency, of high-pressure 
polyethylene and the unsatisfactory levels of such properties and heat 
resistance of conventional ethylene copolymers, and exhibit unique 
structural characteristics not described in the literature. 
High-pressure polyethylene has been considered to have relatively good 
transparency, and is used in the production of melt-shaped articles such 
as films, sheets and hollow containers. Since, however, the high-pressure 
polyethylene films have unsatisfactory tear strength or impact strength, 
and are difficult to use as thin films, they have only limited 
applications. Furthermore, films having superior transparency are 
difficult to obtain by the inflation molding of high-pressure 
polyethylene. It has been desired therefore to develop olefinic resins 
having improved transparency. 
Generally, copolymers of ethylene with .alpha.-olefins having at least 3 
carbon atoms which are produced by using a Ziegler type catalyst have much 
the same density as high-pressure polyethylene, and exhibit relatively 
good mechanical strength. When produced by using a vanadium-containing 
Ziegler-type catalyst, such copolymers have relatively low melting points, 
and have unsatisfactory thermal resistance. In the presence of a 
titanium-containing Ziegler-type catalyst, copolymers of ethylene with 
.alpha.-olefins having at least 3 carbon atoms are obtained which have 
poor transparency. 
In the production of such copolymers catalyzed by the titanium-containing 
Ziegler catalysts, copolymers having much the same transparency as 
high-pressure polyethylene could be produced by properly modifying the 
polymerization conditions or the catalysts (disclosed, for example, in 
Canadian Pat. No. 986,250 assigned to Mitsui Petrochemical Industries, 
Ltd., issued on Mar. 23, 1976; corresponding to British Pat. No. 1,355,245 
published on Oct. 2, 1974). It has been impossible in practice, however, 
to provide ethylene copolymers having superior tear resistance and impact 
resistance which eliminate the unsatisfactory levels of these properties 
in high-pressure polyethylene films, and exhibit better transparency. The 
above-cited Canadian Patent does not specifically disclose copolymers of 
ethylene with .alpha.-olefins having 5 to 18 carbon atoms. 
We have worked extensively in an attempt to develop ethylene copolymers 
having the aforesaid improved properties, and consequently found that 
there exist ethylene copolymers consisting essentially of ethylene and 
.alpha.-olefins with 5 to 18 carbon atoms which have unique structural 
characteristics not described in the literature and which exhibit the 
aforesaid improved properties. 
It is an object of this invention therefore to provide an ethylene 
copolymer having unique structural characteristics not described in the 
literature and the aforesaid improved properties. 
The above and other objects and advantages of the invention will become 
more apparent from the following description. 
The ethylene copolymers of this invention consisting essentially of 
ethylene and .alpha.-olefins with 5 to 18 carbon atoms have the structural 
characteristic that as compared with ethylene copolymers described in the 
literature and being available on the market, they have an exceedingly 
high weight average molecular weight, &lt;M&gt;.sub.w, (determined by the light 
scattering method) even when they have the same intrinsic viscosities 
[.eta.] as the conventional ethylene copolymers. In the present invention, 
this characteristic is defined as follows: 
EQU g.sub..eta. *=[.eta.]/[.eta.]l is 0.05-0.78, preferably 0.05-0.5. (iv) 
[.eta.] is the intrinsic viscosity of the copolymer of this invention; and 
[.eta.]l is the intrinsic viscosity of a linear polyethylene having the 
same weight average molecular weight (determined by the light scattering 
method) as the copolymer of this invention. 
[.eta.] is determined in decalin at 135.degree. C. 
The intrinsic viscosity [.eta.].sub.l of a linear polyethylene having the 
same weight average molecular weight &lt;M&gt;.sub.w (determined by the light 
scattering method) as that of the copolymer of this invention having the 
intrinsic viscosity [.eta.] is calculated in accordance with the following 
equation. 
EQU [.eta.].sub.l =5.29.times.10.sup.-4 .times.&lt;M&gt;.sub.w 0.713 
The g.sub..eta. * values much smaller than 1 show the structural 
characteristic that many long-chain branchings exist in the copolymer in 
addition to short-chain branchings derived from the C.sub.5 -C.sub.18 
.alpha.-olefin copolymerized with ethylene (for example, isobutyl 
branchings when the .alpha.-olefin is 4-methyl-1-pentene). That the 
ethylene copolymers of this invention have a g.sub..eta. * value of 0.05 
to 0.78, preferably 0.05 to 0.5 shows that the ethylene copolymers of this 
invention are very different in structure from conventional ethylene 
copolymers having substantially only short-chain branchings and a 
g.sub..eta. * value of 0.80 to 1.0. The transparency of the conventional 
ethylene copolymers having a g.sub..eta. * value of 0.80 to 1.0 is at best 
equivalent to that of the high-pressure polyethylene, and frequently 
inferior to the latter. 
In addition to the aforesaid structural characteristic (iv), the ethylene 
copolymers of this invention have the following structural characteristics 
(i) to (iii). 
(i) They have a density of 0.90 to 0.94 g/cm.sup.3, preferably 0.91 to 
0.935 g/cm.sup.3. 
(ii) They have an intrinsic viscosity [.eta.] of 0.8 to 4.0 dl/g, 
preferably 1.0 to 3.0 dl/g. 
(iii) They have a maximum melting point, determined by differential thermal 
analysis (DSC), of 115.degree. to 130.degree. C., and in many cases 
115.degree. to 125.degree. C. 
The maximum melting point, as referred to in (iii) above, denotes the 
highest melting point among two or more melting points (peaks) which 
usually exist in the DSC endothermic curve of the ethylene copolymer of 
this invention. 
In order for the copolymer of this invention to have good transparency, it 
should have a density of not more than 0.94 g/cm.sup.3, preferably not 
more than 0.935 g/cm.sup.3. On the other hand, to secure superior 
mechanical characteristics, and freedom from stickiness, the copolymer of 
this invention should have a density of at least 0.90 g/cm.sup.3, and 
preferably at least 0.91 g/cm.sup.3. 
The instrinsic viscosity [.eta.] of the copolymer of this invention is 0.8 
to 4.0 dl/g, preferably 1.0 to 3.0 dl/g, and for use as films, its 
suitable intrinsic viscosity [.eta.] is 1.0 to 3.0 dl/g. 
Preferably, the ethylene copolymers of this invention consisting 
essentially of ethylene and .alpha.-olefins with 5 to 18 carbon atoms 
should have the following characteristics (v) to (vii) in addition to the 
characteristics (i) to (iv). 
(v) They have an average spherulite size, determined by the small angle 
laser scattering method, of not more than 6.mu., preferably not more than 
4.mu.. 
(vi) They have two or more melting points determined by differential 
thermal analysis (DSC). 
(vii) They have a standard deviation (.delta.) of the distribution of 
ethylene content of not more than 3%, preferably 1 to 2.5%. 
The characteristics (v) means that the ethylene copolymers of this 
invention have much smaller average spherulite sizes than the conventional 
ethylene copolymers having the same composition of constituent units. 
The average spherulite size (R) is determined by the small angle laser 
scattering method using a 70.mu.-thick press sheet which is obtained by 
heating the copolymer to 220.degree. C. and pressing it with water cooling 
at a pressure of 100 kg/cm.sup.2 -G. Specifically, using a small angle 
laser scattering device, an Hv scattering pattern is obtained when the 
polarizer in the incident beam is vertical and the analyser in the 
scattered beam is horizontal. Then, the scattering angle .theta..sub.m 
which gives the maximum value in the distribution of the scattering 
intensity in the scattering pattern is determined, and the spherulite size 
(R) is obtained from the following equation. 
##EQU1## 
(R. S. Stein's equation; see J. Appl. Phys., Vol. 31, No. 11, 1873 (1960)) 
The structural characteristic (vi) means that the ethylene copolymers of 
this invention include two or more crystal types. For example, as shown in 
FIG. 1, a copolymer of ethylene with 4-methyl-1-pentene of this invention 
which has a g.sub..eta. * of 0.13, an [.eta.] of 1.42 dl/g, a density of 
0.926 g/cm.sup.3 and a maximum melting point in DSC of 122.degree. C. has 
melting points at 108.degree. C., 119.degree. C. and 122.degree. C. in its 
DSC endothermic curve. This shows that in this example, three crystal 
types exist. For comparison, FIG. 2 shows the DSC endothermic curve of a 
comparative copolymer of ethylene with 4-methyl-1-pentene having a 
g.sub..eta. * of 0.83, an [.eta.] of 1.53 dl/g, a density of 0.927 
g/cm.sup.3 and a melting point of 125.degree. C. In this example, only one 
melting point is found at 125.degree. C., and this shows that only one 
crystal type exists. 
The characteristic (vii) shows that the ethylene copolymers of this 
invention have a very narrow distribution of the content of ethylene. The 
standard deviation (.delta.) is calculated from the following equation. 
##EQU2## 
wherein x.sub.i is the content of ethylene, x is the average of x.sub.i 
values, and 
##EQU3## 
and .omega..sub.i is the proportion by weight. 
For example, the copolymer shown in FIG. 1 has a standard deviation 
(.delta.) of 1.35 mole%, and the copolymer shown in FIG. 2 shows a 
standard deviation (.delta.) of 3.72 mole%. 
Fractionation of the copolymer of this invention according to chemical 
composition is performed by fractionating it into five fractions by the 
Soxhlet extraction method, and the number of short-chain branchings 
derived from the .alpha.-olefin is determined by infrared absorption 
spectroscopy. The five fractions are as follows: 
(1) A fraction soluble in p-xylene at room temperature 
(2) A fraction extracted with boiling n-hexane 
(3) A fraction extracted with boiling benzene 
(4) A fraction extracted with boiling n-heptane 
(5) A fraction extracted with boiling p-xylene 
Examples of the .alpha.-olefin comonomer which constitutes the copolymer of 
this invention are 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 
1-tetradecene, 1-octadecene, 3-methyl-1-butene, 3-methyl-1-pentene, 
4-methyl-1-pentene, 3-methyl-1-hexene, 4-methyl-1-hexene, 
5-methyl-1-hexene, 3-methyl-1-heptene, 5-methyl-1-heptene, and mixtures of 
these. Preferred .alpha.-olefins are those containing 6 to 12 carbon 
atoms, above all 1-hexane, 1-octene, 1-decene, 3-methyl-1-pentene, 
4-methyl-1-pentene, 5-methyl-1-hexane and 5-methyl-1-heptane. 
4-Methyl-1-pentene is especially preferred. 
The proportion of the comonomer to be copolymerized can be varied as 
desired according to the type of the comonomer. To afford a copolymer 
having the density specified by (i) above, the suitable proportion of the 
comonomer is usually about 1 to about 30% by weight, preferably about 3 to 
about 20% by weight, based on the weight of the copolymer. When an 
.alpha.-olefin having not more than 4 carbon atoms is selected as the 
comonomer, a copolymer having superior mechanical strength and/or 
transparency specified in the present invention cannot be obtained. 
In the production of the ethylene copolymer of this invention, the 
selection of the catalyst and the polymerization conditions are important. 
Preferably, the catalyst to be used is a catalyst composed of a solid 
titanium catalyst component and an organoaluminum compound. The use of a 
catalyst composed of a solid, magnesium-containing titanium catalyst 
component and an organoaluminum compound is more preferred. Especially 
preferred catalysts are those in which the solid titanium catalyst 
component is the one which is obtained by supporting titanium on a 
compound containing a magnesium halide, especially magnesium chloride, and 
which has a Cl/Ti weight ratio of 5 to 150, an Mg/Ti mole ratio of 3 to 
90, and a surface area of at least 70 m.sup.2 /g, preferably more than 150 
m.sup.2 /g. Of these catalysts composed of such preferred solid titanium 
catalyst components and organoaluminum compounds, especially suitable ones 
are the catalysts disclosed in British Pat. No. 1,433,537 published on 
Aug. 25, 1976 (corresponding to German OLS No. 2,346,471 laid open on Apr. 
18, 1974) and German OLS No. 2,461,677 laid open on July 10, 1975. These 
patents do not give a specific example of copolymerizing ethylene with an 
.alpha.-olefin having 5 to 18 carbon atoms. 
A solid titanium catalyst component which is disclosed in the cited British 
Pat. No. 1,433,537 and has the surface area specified hereinabove can be 
synthesized, for example, by adding about 3 to about 7 moles of a lower 
alcohol such as ethanol to 1 mole of magnesium chloride, reacting the 
adduct with an organoaluminum compound in an amount sufficient to react 
with the alcohol, and then reacting the resulting product with titanium 
tetrachloride or its solution in an inert hydrocarbon. 
The solid titanium catalyst component disclosed in the German OLS No. 
2,461,677 can be prepared by reacting the solid titanium catalyst 
component obtained by the method of the British Pat. No. 1,433,537 further 
with small amounts of titanium tetrachloride and an organoaluminum 
compound. 
The solid titanium catalyst components obtained by these two methods 
contain titanium, magnesium, halogen and aluminum, and a surface area of 
at least 70 m.sup.2 /g, preferably more than 150 m.sup.2 /g but not 
exceeding 500 m.sup.2 /g. 
In addition to the selection of the titanium catalyst component, the 
selection of the organoaluminum compound as another catalyst component is 
of importance in obtaining the copolymers of this invention. Preferred 
organoaluminum compounds are organoaluminum halides of the empirical 
formula R.sub.n AlX.sub.3-n wherein R represents a hydrocarbon group such 
as an alkyl group with 1 to 12 carbon atoms, X represents a halide such as 
chloride, bromide, iodide, and 1.ltoreq.n.ltoreq.2.5, preferably 
1.5.ltoreq.n.ltoreq.2.0, especially preferably 1.5.ltoreq.n.ltoreq.1.8. A 
mixture of two or more such organoaluminum halides can also be used if it 
has an average composition within the above formula. Preferred species are 
alkylaluminum sesquichlorides and dialkylaluminum chloride. The 
alkylaluminum sesquichloride and mixtures thereof with dialkylaluminum 
chloride are especially preferred. 
When a trialkylaluminum, dialkylaluminum hydride, dialkylaluminum alkoxide 
or alkylaluminum alkoxyhydride, all of which are frequently used in the 
polymerization of ethylene, is used as the organoaluminum compound, the 
copolymers obtained usually have a g.eta. * of at least 0.80, a standard 
deviation (.sigma.) of at least 3.0 mole%, an average spherulite size (R) 
of not more than 7.mu., and one or two melting points. 
In the production of the ethylene copolymers of this invention, the 
selection of the copolymerization conditions is important besides the 
selection of the catalyst. 
Copolymerization should be carried out at a temperature above the melting 
point of the copolymer preferably in the co-presence of a hydrocarbon 
solvent, or using the monomer itself as a solvent, and under such 
conditions that the solvent and the resulting copolymer form a homogeneous 
phase. Preferably, the polymerization is carried out continuously while 
maintaining the concentrations of the monomers (ethylene and the 
comonomer) constant. The conditions which will give a homogeneous phase of 
the solvent and the copolymer vary according, for example, to the type of 
the solvent, the concentrations (or pressures) of the monomers (ethylene 
and the comonomer) or hydrogen, the polymerization temperature and the 
molecular weight (intrinsic viscosity) of the copolymer. It is advisable 
therefore to set such conditions by preliminary experiments. 
As an example, FIG. 3 shows the precipitation point in hexane of an 
ethylene/4-methyl-1-pentene copolymer having an intrinsic viscosity 
[.eta.] of 1.42 dl/g, a density of 0.926 g/cm.sup.3, a 4-methyl-1-pentene 
content of 2.9 mole% and melting points of 108.degree. C., 119.degree. C. 
and 122.degree. C. The axis of abscissas represents the total pressure 
(the total pressure of hexane and ethylene, and optionally 
4-methyl-1-pentene, in the case of a gaseous phase), and the axis of 
ordinates represents the temperature (precipitation temperature) at which 
the polymerization system becomes a heterogeneous phase. Curve (1) shows 
precipitation points in a mixture of hexane and 4-methyl-1-pentene (in a 
ratio of 85:15) with a copolymer concentration of 150 g/l; curve (2), 
precipitation points in the same mixture with a copolymer concentration of 
100 g/l; and curve (3), precipitation points in the same mixture with a 
copolymer concentration of 50 g/l. Curve (4) shows precipitation points in 
hexane with a copolymer concentration of 50 g/l. At temperatures higher 
than the precipitation points, a heterogeneous phase results. 
It can be seen from FIG. 3 that when the copolymer concentration is 50 to 
150 g/l, the temperature range within which polymerization can be carried 
out in a homogeneous phase is broader with higher concentration of the 
copolymer and higher pressures. It is also clear from it that the operable 
temperature range differs according to the amounts of the monomers 
(ethylene and the comonomer). 
FIG. 3 represents one model, and in an actual polymerization system, the 
temperature range for attaining a homogeneous phase is set experimentally 
prior to actual operation. 
Low concentrations of the copolymer are not economical, and the operable 
temperature range is narrow at low concentrations. If the concentration of 
the copolymer is too high, the viscosity of the solution rises extremely 
high to inhibit the smooth proceeding of the polymerization reaction. 
Hence, it is usually preferred to maintain the concentration of the 
copolymer at about 50 to about 200 g per liter of the solvent. 
Examples of the hydrocarbon solvent are aliphatic hydrocarbons such as 
n-hexane, n-heptane, iso-hexane, n-pentane, octane, decane and kerosene; 
alicyclic hydrocarbons such as cyclohexane or methylcyclohexane, and 
aromatic hydrocarbons such as benzene, toluene or xylene. 
The suitable amount of the solid titanium catalyst component is 0.0005 to 
1.0 millimole, preferably 0.001 to 0.1 millimole, calculated as titanium 
atom, per liter of the solvent, and the suitable amount of the 
organoaluminum compound is 0.01 to 10 millimoles, preferably 0.05 to 1.0 
millimole, calculated as aluminum, per liter of the solvent. It is 
preferred that at this time, the Al/Ti mole ratio be adjusted to at least 
1. 
The proportion of the .alpha.-olefin with 5 to 18 carbon atoms to be fed to 
the polymerization system, which varies according, for example, to the 
type of the .alpha.-olefin, the polymerization temperature and the partial 
pressure of ethylene in the polymerization vessel, is 0.05 to 20 moles, 
preferably 0.10 to 5 moles, per mole of ethylene. Preferably, the 
polymerization is carried out under elevated pressures of, say, 2 to 100 
kg/cm.sup.2, preferably 15 to 70 kg/cm.sup.2. The molecular weight of the 
copolymer is adjusted preferably by using hydrogen. 
The copolymers of this invention have better transparency, tear resistance 
and impact resistance than high-pressure polyethylene, and are suitable 
for use as films. These superior properties along with their very good 
heat-sealability indicate their suitability as packaging films. Films of 
these copolymers, whether obtained by a T-die method or an inflation 
method, have a high level of transparency. The copolymers of this 
invention can also be formed into various shaped articles by, for example, 
blow molding, injection molding, or extrusion molding. Multilayer films 
can also be prepared by extrusion coating on other films. They can also be 
used as blends with other thermoplastic resins, for example olefin 
polymers such as polyethylene, polypropylene, poly-1-butene 
poly-4-methyl-1-pentene, an ethylene/propylene copolymer, an 
ethylene/butene copolymer or a propylene/1-butene copolymer. They can also 
be incorporated with petroleum resins, waxes, stabilizers, antistatic 
agents, ultraviolet absorbers, synthetic or natural rubbers, lubricants, 
inorganic fillers, etc.

The following examples illustrate the present invention in more detail. 
EXAMPLE 1 
Preparation of Catalyst 
In a stream of nitrogen, 10 moles of commercially available anhydrous 
magnesium chloride was suspended in 50 liters of dehydrated and purified 
hexane, and with stirring 60 moles of ethanol was added dropwise over the 
course of 1 hour. The reaction was carried out for 1 hour at room 
temperature. To the reaction product was added dropwise 27 moles of 
diethylaluminum chloride, and the mixture was stirred for 1 hour at room 
temperature. Subsequently, 100 moles of titanium tetrachloride was added. 
The mixture was heated to 70.degree. C., and reacted for 3 hours with 
stirring. The resulting solid was separated by decantation, and repeatedly 
washed with purified hexane to form a suspension of it in hexane. The 
concentration of titanium was determined by titration. 
Polymerisation 
A 200 liter continuous polymerization reactor was charged continuously with 
80 liters/hr of dehydrated and purified hexane, 32 millimoles/hr of 
ethylaluminum sesquichloride, and 1.2 millimoles/hr, calculated as 
titanium, of the carrier-supported catalyst component prepared as above. 
Into the polymerization reactor, 13 kg/hr of ethylene, 13.0 kg/hr of 
4-methyl-1-pentene, and 100 liters/hr of hydrogen were fed simultaneously. 
At a temperature of 145.degree. C. and a total pressure of 30 kg/cm.sup.2 
-G, these monomers were copolymerized while maintaining the residence time 
at 1 hour, and the concentration of the copolymer at 112 g per liter of 
hexane. The resulting copolymer had a density of 0.922 g/cm.sup.3, a melt 
index of 2.24 and a molecular weight &lt;M.eta..sub.w of 2,560,000, and 
contained 13.2 isobutyl groups per 1000 carbon atoms. A rapidly cooled 
press-formed sheet of the copolymer having a g.sub.72 * of 0.09 and a 
thickness of 70.mu. had an average spherulite size (R) of 1.5.mu.. 
A film having a width of 350 mm and a thickness of 30.mu. was prepared from 
the copolymer by a tubular film-forming machine for high-pressure 
polyethylene (made by Modern Machinery). The molding conditions were as 
follows: the resin temperature 180.degree. C.; the speed of screw rotation 
100 revolutions per minute; the die diameter 100 mm; and the width of the 
die slit 0.7 mm. 
The results are shown in Table 1. 
Commercially available high-pressure polyethylenes shown in Table 4 were 
molded in the same way as above, and the results are shown in Table 4. 
(Comparative Examples 7 to 11). 
EXAMPLE 2 AND COMATIVE EXAMPLES 1 to 3 
Various ethylene/4-methyl-1-pentene copolymers were prepared under the 
conditions described in Table 1 using the titanium catalyst component 
prepared in Example 1. The properties of these copolymers are shown in 
Table 1. 
The aluminum catalyst component used in Comparative Example 2 was obtained 
by reacting 0.5 mole of ethyl alcohol with 1 mole of triethyl aluminum. 
Table 1 
__________________________________________________________________________ 
Example (Ex.) or Compara- 
tive Example (CEx.) 
Ex. 1 Ex. 2 CEx. 1 
CEx. 2 
CEx. 3 
__________________________________________________________________________ 
Polymerization conditions 
Ethylene (kg/hr) 13 13.5 14.0 13.5 13.5 
4-Methyl-1-pentene (kg/hr) 
13.0 14.4 18.0 16.0 16.5 
Hydrogen (l/hr) 100 70 40 50 50 
Hexane (l/hr) 80 80 80 80 80 
Titanium catalyst component 
(millimoles/hr, calculated 
1.2 0.70 0.28 0.32 0.4 
as Ti) 
Aluminum catalyst component 
Ethyl Ethyl Triethyl 
Ethyl Diethyl 
(millimoles/hr) aluminum 
aluminum 
aluminum 
aluminum 
aluminum 
sesqui- 
sesqui- 
(20) ethoxide 
hydride 
chloride (32) 
chloride (16) 
(20) (24) 
Diethyl 
aluminum 
chloride (8) 
Temperature (.degree.C.) 
145 145 145 145 145 
Pressure (Kg/cm.sup.2 -G) 
30 30 30 30 30 
Residence time (hr) 
1 1 1 1 1 
Concentration of polymer 
(g/l-hexane) 112 119 128 115 115 
Properties of the copolymer 
Ethylene content (mole %) 
97.2 96.5 96.1 97.1 96.9 
Density (g/cm.sup.3) 
0.922 0.923 0.920 0.926 0.925 
Number of isobutyl groups 
13.2 17.0 20.1 13.8 14.5 
(per 1000 carbon atoms) 
Melt index 2.24 4.05 4.65 5.22 4.30 
Melting point (.degree.C.) 
114,119 
116,122 
121,124 
124.5 125 
Molecular weight, &lt;M&gt;.sub.w .times. 10.sup.-4 
256 36.3 9.8 7.7 8.4 
Intrinsic viscosity (.eta.) (dl/g) 
1.71 1.55 1.56 1.49 1.56 
g.sub..eta. * 0.09 0.35 0.83 0.93 0.92 
Standard deviation (.sigma.) (mole %) 
1.26 2.12 3.86 4.10 4.03 
Average spherulite size R (.mu.) 
of a 70.mu.-thick rapidly cooled 
1.5 1.7 6.1 6.6 6.2 
press-formed sheet 
Haze of 30.mu.-thick inflation film 
(%) 0.9 2.0 14 23 18 
Impact strength (kg . cm/cm) 
2900 2600 2000 1900 2100 
Elmendorf tear strength (kg/cm) 
Machine direction 142 101 63 14 24 
Transverse direction 
181 161 118 70 88 
__________________________________________________________________________ 
EXAMPLE 3 
Preparation of Catalyst 
In a stream of nitrogen, 10 moles of commercially available magnesium 
chloride was suspended in 50 liters of dehydrated and purified hexane, and 
with stirring, 60 moles of ethanol was added dropwise over the course of 1 
hour. The reaction was then performed for 1 hour at room temperature. To 
the reaction product was added dropwise 28 moles of diethylaluminum 
chloride at room temperature, and the mixture was stirred for 1 hour. 
Subsequently, 7 moles of titanium tetrachloride and 7 moles of triethyl 
aluminum were added, and the reducing reaction was performed at room 
temperature for 4 hours with stirring. The solid portion turned light 
brown which is a color peculiar to trivalent titanium. The titanium 
concentration of the resulting hexane suspension was determined by 
titration. 
Polymerization 
The same continuous polymerization apparatus as used in Example 1 was 
charged continuously with 80 l/hr of nexane, 32 millimoles/hr of 
ethylaluminum sesquichloride and 1.2 millimoles/hr, calculated as 
titanium, of the supported catalyst component. Into the polymerization 
vessel, 12.5 kg/hr of ethylene, 11.0 kg/hr of 4-methyl-1-pentene and 110 
l/hr of hydrogen were continuously fed simultaneously. At a temperature of 
145.degree. C. and a total pressure of 30 kg/cm.sup.2 -G, the monomers 
were copolymerized while maintaining the residence time at 1 hour, and the 
concentration of the copolymer at 110 g per liter of the hexane. The 
properties of the resulting copolymer, and the properties of its molded 
products prepared in the same way as in Example 1 are shown in Table 2. 
EXAMPLE 4 AND COMATIVE EXAMPLES 4 and 5 
Various ethylene/4-methyl-1-pentene copolymers were prepared under the 
conditions shown in Table 2 using the titanium catalyst component prepared 
in Example 3. The results are also shown in Table 2. 
Table 2 
__________________________________________________________________________ 
Example (Ex.) or Compara- 
tive Example (CEx.) Ex. 3 Ex. 4 CEx. 4 CEx. 5 
__________________________________________________________________________ 
Polymerization conditions 
Ethylene (kg/hr) 12.5 13.5 13.5 13.0 
4-Methyl-1-pentene (kg/hr) 
11.0 16.0 15.0 16.0 
Hydrogen (l/hr) 110 50 50 60 
Hexane (l/hr) 80 80 80 80 
Titanium catalyst component 
(millimoles/hr, calculated as Ti) 
1.2 0.4 0.32 0.4 
Aluminum catalyst component 
Ethyl Diethyl 
Triisobutyl 
Diisobutyl 
(millimoles/hr) aluminum 
aluminum 
aluminum (24) 
aluminum 
sesqui- 
chloride (20) hydride (24) 
chloride (32) 
Temperature (.degree.C.) 
145 145 145 145 
Pressure (Kg/cm.sup.2 -G) 
30 30 30 30 
Residence time (hr) 1 1 1 1 
Concentration of polymer 
(g/l-hexane) 110 118 105 108 
Properties of the copolymer 
Ethylene content (mole %) 
97.1 96.8 96.6 96.7 
Density (g/cm.sup.3) 
0.926 0.924 0.924 0.924 
Number of isobutyl groups 
13.9 15.2 16.1 15.8 
(per 1000 carbon atoms) 
Melt index 4.58 4.68 4.43 4.32 
Melting point (.degree.C.) 
108,119,122 
120,123 
124.5 124 
Molecular weight, &lt;M&gt;.sub.w .times. 10.sup.-4 
137 41.5 9.2 8.5 
Intrinsic viscosity (.eta.) (dl/g) 
1.42 1.45 1.53 1.52 
g.sub..eta. 0.13 0.30 0.85 0.89 
Standard deviation (.sigma.) (mole %) 
1.35 2.14 3.91 3.35 
Average spherulite size R(.mu.) of a 
70.mu.-thick rapidly cooled press- 
1.2 1.8 7.3 6.3 
formed sheet 
Haze of 30.mu.-thick inflation 
film (%) 0.8 2.5 28 19 
Impact strength (kg . cm/cm) 
2800 2500 2100 2200 
Elmendorf fear strength (kg/cm) 
Machine direction 128 102 32 45 
Transverse direction 
194 171 101 81 
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EXAMPLE 5 
Ethylene and an .alpha.-olefin mixture (Dialene 610, a trademark for a 
product of Mitsubishi Chemical Co., Ltd.; mixture of 35.9% of 1-hexene, 
33.3% of 1-octene and 30.8% of 1-decene) were simultaneously fed 
continuously into a polymerization vessel, and copolymerized under the 
conditions shown in Table 3 using the titanium catalyst component 
described in Example 3. The properties of the resulting copolymer and its 
molded articles prepared in the same way as in Example 1 are shown in 
Table 3. 
EXAMPLE 6 and Comparative Example 6 
In the same way as in Example 5, ethylene and an .alpha.-olefin mixture 
(Dialene 124, a trademark for a product of Mitsubishi Chemical Co., Ltd.; 
mixture consisting of 56.6% of 1-dodecene and 43.4% of 1-tetradecene) or 
1-butene were continuously polymerized. The properties of the copolymers 
obtained are shown in Table 3. 
Table 3 
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Example (Ex.) or Compara- 
tive Example (CEx.) Ex. 5 Ex. 6 CEx. 6 
__________________________________________________________________________ 
Polymerization conditions 
Ethylene (kg/hr) 14.0 13.5 13.0 
.alpha.-Olefin (kg/hr) 
Olefin mixture 
Olefin mixture 
1-Butene 
(15.0) (15.0) (8.0) 
Hydrogen (l/hr) 60 60 60 
Hexane (l/hr) 80 80 80 
Titanium catalyst component 
(milimoles/hr, calculated as Ti) 
0.5 0.8 0.4 
Aluminum catalyst component 
Diethylaluminum 
Diethylaluminum 
Triethylaluminum 
(millimoles/hr) chloride (25) 
chloride (40) 
(28) 
Temperature (.degree.C.) 
145 145 145 
Pressure (Kg/cm.sup.2 -G) 
30 30 30 
Residence time (hr) 1 1 1 
Concentration of polymer 
(g/l-hexane) 125 117 115 
Properties of the copolymer 
Ethylene content (mole %) 
97.8 98.6 95.2 
Density (g/cm.sup.3) 
0.922 0.925 0.919 
Melt index 3.15 3.91 2.09 
Melting point (.degree.C.) 
107,122.5 
110,123.5 
123 
Molecular weight, &lt;M&gt;.sub.w .times. 10.sup.-4 
13.6 14.7 11.6 
Intrinsic viscosity (.eta.) (dl/g) 
1.70 1.60 1.75 
g.sub..eta. 0.70 0.63 0.81 
Standard deviation (.sigma.) (mole %) 
2.23 2.36 -- 
Average spherulite size R(.mu.) of a 
70.mu.-thick rapidly cooled press- 
1.6 1.7 4.2 
formed sheet 
Haze of 30.mu.-thick inflation 
1.0 2.0 12 
film (%) 
Impact strength (kg . cm/cm) 
2500 2400 830 
Elmendorf tear strength (kg/cm) 
Machine direction 110 105 73 
Transverse direction 
183 165 60 
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Table 4 
__________________________________________________________________________ 
Comparative Examples 
7 8 9 10 11 
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Properties of the polymer 
Density (g/cm.sup.3) 
0.923 
0.922 
0.924 
0.924 
0.921 
Number of methyl groups 
(per 1000 carbon atoms) 
16.0 17.7 14.4 18.2 14.9 
Melt index 1.0 2.0 2.8 2.5 3.2 
Melt Point (.degree.C.) 
112 110 113 111 108 
Molecular weight, &lt;M&gt;.sub.w .times. 10.sup.-4 
20.0 14.3 16.7 19.2 20.4 
Intrinsic viscosity (.eta.) (dl/g) 
1.07 1.01 0.99 1.10 1.08 
g.sub..eta. 0.34 0.40 0.35 0.36 0.33 
Haze of 30.mu.-thick inflation 
8.1 4.9 4.7 4.3 6.0 
film (%) 
Impact strength (kg . cm/cm) 
1700 1400 1500 1300 1600 
Elmendorf tear strength(kg/cm) 
Machine direction 
157 115 157 103 84 
Transverse direction 
78 107 73 87 96 
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