JPH06172594A - Polyethylene composition - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a polyethylene composition suitable for large hollow moldings, which has a wide molecular weight distribution, an excellent balance of melt elasticity, flow properties, mechanical properties, etc., and particularly excellent mechanical properties at low temperatures. To do. [Constitution] In the elution temperature-elution amount curve of the continuous temperature rising elution fractionation method (TREF), 9 for elution amounts of 90 ° C. or higher
An area ratio of the elution amount at 0 ° C. or less and an orthodichlorobenzene-soluble content satisfy a specific relationship, respectively. Polyethylene composition.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is excellent in melt elasticity (melt tension, die swell ratio, etc.), flow characteristics (processing characteristics, etc.), mechanical characteristics (impact resistance, tensile strength, etc.), and has an extremely high molecular weight distribution. With respect to a wide range of polyethylene compositions, polyethylene compositions suitable for large hollow molded products such as gasoline tanks and extruded products such as large diameter pipes, etc., because of their excellent mechanical properties at low temperature, large melt tension and large die swell ratio. Regarding

[0002]

2. Description of the Related Art Heretofore, a method of broadening the molecular weight distribution of an ethylene / α-olefin copolymer has been reported for the purpose of improving flow characteristics (for example, JP-A-57-21409 and JP-B-63-47741). However, melt elasticity and mechanical properties, especially mechanical properties at low temperatures, are not improved by merely broadening the molecular weight distribution in this way, but rather greatly decrease. In addition, regarding the improvement of mechanical properties and flow properties, the short chain branching degree of the high molecular weight component of the ethylene / α-olefin copolymer consisting of the high molecular weight component and the low molecular weight component was specified and Attempts have been made to improve not only mechanical properties and fluidity but also environmental stress crack resistance (ESCR) by introducing a large number of branches (Japanese Patent Laid-Open No. 54-10044, Japanese Patent Publication No. 64-7096).
Issue). However, even in these cases, the mechanical properties, especially the mechanical properties at low temperature and the melt elasticity are not satisfactory. Further, Japanese Patent Laid-Open No. 2-305811 proposes a method of specifying a catalyst and polymerization conditions of two-step polymerization for the purpose of improving impact resistance, ESCR, and pinch-off fusing property. , ESCR and melt elasticity are slightly improved, but they are not sufficient to improve mechanical properties, especially at low temperature. In addition, a polyethylene composition for blow molding which has improved drawdown resistance, die swell ratio and ESCR (JP-A-59-8).
No. 9341, JP-A-60-20946, etc.), and a three-step polymerization method has been proposed as a method for improving the drawbacks of the two-step polymerization method (Japanese Patent Publication No. 59-10724).
JP-A Nos. 62-25105 and 62-25106,
62-25107, 62-25108, 6
2-25109, etc.). Even in these cases, the melt elasticity and flow characteristics are still insufficient, and no improvement is seen in the mechanical characteristics especially at low temperatures.

[0003]

In view of the above points, the present invention is directed to melt elasticity (melt tension, die swell ratio, etc.),
A polyethylene composition that has an excellent balance of physical properties such as flow characteristics (processing characteristics) and mechanical characteristics (impact resistance, tensile strength, etc.), and has an extremely wide molecular weight distribution. Due to the large melt tension and die swell ratio, large hollow molded products such as gasoline tanks,
An object of the present invention is to provide a polyethylene composition suitable for extruded products such as large diameter pipes.

[0004]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors in view of the above objects, the inventors have found that a specific high molecular weight component and a specific ethylene / α having an extremely wide short chain branch distribution between molecules are used.
-By blending with a low molecular weight component consisting of an olefin copolymer or an ethylene homopolymer having no short chain branching, excellent balance of various physical properties such as melt elasticity, flow properties, mechanical properties, especially at low temperature The present invention has been accomplished by finding that a polyethylene composition having excellent mechanical properties can be obtained. That is, the present invention provides (I) 1 to 50% by weight of a high molecular weight ethylene homopolymer or ethylene / α-olefin copolymer satisfying the following (a) and (b), (a) intrinsic viscosity (η ₁ ) 9-45 dl / g (b) Density (d ₁ ) 0.890 to 0.935 g / cm ³ and (II) Low molecular weight ethylene homopolymer or ethylene / α- which satisfies the following (c) to (f) Olefin Copolymer 99
˜50 wt% (c) Intrinsic viscosity (η ₂ ) 0.3 to 3.0 dl / g (d) Density (d ₂ ) 0.890 to 0.980 g / cm ³ (e) By continuous temperature rising elution fractionation method In the elution temperature-elution amount curve, the ratio S (Ib / of the area Ib at the elution temperature of 25 to 90 ° C. to the area Ia under the curve at the elution temperature of 90 ° C. or more
Ia) is less than or equal to S ₁ calculated from the following equation, S ₁ = 20η ₂ ⁻¹ exp [−50 (d ₂ − 0.900)] (f) 25 ° C. ortho-dichlorobenzene soluble content W weight% is calculated from the following equation. that W ₁ or ^{_{less, W 1 = 100η 2 -0.5 exp}} [- 50η 2 0.5 (d 2 - 0.900)] a mixture consisting of, and the intrinsic viscosity of the mixture (eta) is 1~10dl / g, a density ( d) 0.890 to 0.97
N-value calculated from 0 g / cm ³ and the following equation 2 is 1.7 to
A polyethylene composition of 3.0 is provided.

[0005]

[Equation 2]

The details of the present invention will be described below. The high molecular weight component (I) of the present invention is an ethylene homopolymer or an ethylene / α-olefin copolymer, and the α-olefin of the copolymer has a carbon number of 3 to 18, Particularly, those having 4 to 10 carbon atoms are preferable from the viewpoint of mechanical properties. Specifically, 1-butene, 1-pentene, 1
-Hexene, 4-methyl-1-pentene, 1-octene, 1-nonene, 1-decene and the like. Α-
Two or more olefins may be used in combination without any problem. The ethylene homopolymer or ethylene / α-olefin copolymer as the high molecular weight component (I) has (a) an intrinsic viscosity (η ₁ ) of 9.0 to 45 dl / g, preferably 10 to 40 dl / g.
g, more preferably 12 to 40 dl / g is used. When η ₁ is less than 9.0 dl / g, the melt elasticity and mechanical properties of the obtained composition are deteriorated, and 45 dl / g
If it exceeds, the molding processability such as the surface roughness of the molded product and the generation of fish eyes deteriorates. The components (I) (b) Density (d ₁₎ is in the range of 0.890~0.935g / cm ^3, is preferably 0.890~0.930g / cm ³ is used. d ₁
Of less than 0.890 g / cm ³ is difficult to manufacture, and
It is not preferable because it causes stickiness of the obtained composition. On the other hand, when d ₁ exceeds 0.935 g / cm ³ , the mechanical properties of the composition, particularly at low temperature, are deteriorated, which is not preferable.

Component (II) which is a low molecular weight component of the present invention
Is an ethylene homopolymer or an ethylene / α-olefin copolymer. As the α-olefin of the ethylene / α-olefin copolymer, those having 3 to 18 carbon atoms are used as in the case of the component (I), preferably 4 carbon atoms.
10 to 10, and particularly 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-nonene, 1-decene and the like are preferable in terms of mechanical properties and the like. It should be noted that two or more α-olefins may be used in combination. The (c) intrinsic viscosity (η ₂ ) of the above component (II) is in the range of 0.3 to 3.0 dl / g, preferably 0.6 to 3.0 dl / g. If η ₂ is less than 0.3 dl / g, the mechanical properties of the composition obtained, particularly at low temperatures, will deteriorate, while if it exceeds 3.0 dl / g, its flow properties will deteriorate. Is also not preferable. The component (II) has a (d) density (d ₂ ) of 0.890 to 0.980 g / c.
A range of m ³ is used, preferably a range of 0.900 to 0.976 g / cm ³ . Those having d ₂ of less than 0.890 g / cm ³ are not preferable because they are difficult to produce and cause stickiness of the obtained composition. On the other hand, when it exceeds 0.980 g / cm ³ , not only is it difficult to produce, but also the mechanical properties of the obtained composition deteriorate, which is also not preferable.

The above regarding the component (II) used in the present invention
The condition (e) is that the high branching component containing many short chain branches dissolves in the solvent at a low temperature, but the low branching component containing few short chain branches does not dissolve in the solvent unless it is at a high temperature. , The branch distribution is quantitatively defined. That is, L. Wild et al.'S continuous elevated temperature elution fractionation method (Temperature Rising Elution Fract
ionation (TREF) ； Journal of Polymer Science: Polymer
r Physics Edition, Vol. 20, 441-455 (1982)), in the elution temperature-elution amount curve, between the area Ia under the curve at an elution temperature of 90 ° C or higher and the same area Ib at an elution temperature of 25 to 90 ° C. It is necessary for a specific relationship to be established, and in the present invention, the area ratio S = Ib / I shown in the schematic diagram of FIG.
The value of a must be less than or equal to S ₁ obtained from the following equation. S ₁ = 20 η ₂ ^-1 exp [-50 (d ₂ -0.900)] When the value of S exceeds S ₁ , the branch distribution becomes almost uniform, resulting in mechanical properties, especially at low temperature. The extremely effective high branching component is relatively decreased, which is not preferable.

Component (II) (f) 25 ° C. used in the present invention
The ortho-dichlorobenzene-soluble content is so low that the elution temperature is too low to be quantified by the continuous temperature-rising elution fractionation method described above.
It represents the amount of a component having an extremely large amount of branching, and needs to be a specific value corresponding to the intrinsic viscosity and the density. However, this also indicates the presence of a non-useful low molecular weight component, which should be eliminated as much as possible. For this purpose, the W content by weight of the soluble component must be W ₁ or less obtained from the following equation. It is preferably W ₂ or less. W ₁ = 100 η ₂ ^-0.5 exp [-50 η ₂ ^0.5 (d ₂ -0.900)] W ₂ = 90 η ₂ ^-0.5 exp [-50 η ₂ ^0.5 (d ₂ -0.900)] When the value of W is W ₁ or more, it is extremely high. It shows that in addition to the components having a large amount of branching, there is a low molecular weight component which is not useful, and the mechanical properties, especially at low temperatures, are degraded.

In the present invention, the mixing ratio of the component (I) and the component (II) is 1 to 50% by weight of the component (I) and the component (II).
It is from 99 to 50% by weight. Particularly for large hollow molded articles such as gasoline tanks, 30 to 50% by weight and 70 to 50% by weight are preferable, respectively. The amount of component (I) is 1
If it is less than 50% by weight, melt elasticity and mechanical properties, particularly mechanical properties at low temperature, are deteriorated, while if it exceeds 50% by weight, flow properties are deteriorated.

The polyethylene composition of the present invention can be obtained by blending both components (I) and (II) as described above.
The properties of the composition after compounding must be within a specific range. That is, the intrinsic viscosity (η) of the polyethylene composition is 1 to 10 dl / g, preferably 1.5 to 9 dl / g. When η is less than 1 dl / g, melt viscosity and mechanical properties,
In particular, the mechanical properties at low temperatures deteriorate, while when it exceeds 10 dl / g, the flow properties deteriorate, so both are not preferable. The density (d) of the polyethylene composition is 0.8
90 to 0.970 g / cm ³ , preferably 0.900 to
It is 0.970 g / cm ³ . When d is less than 0.890 g / cm ^3, it is difficult to produce and it causes stickiness of the composition, and when it exceeds 0.970 g / cm ³ , mechanical properties are deteriorated. Furthermore, the N-value of the polyethylene composition is 1.7.
It is necessary to be ~ 3.0, preferably 1.7-
It is 2.8. When the N-value is less than 1.7, high-speed moldability is deteriorated, and when it exceeds 3.0, melt fracture tends to occur.

The method for producing the polyethylene composition of the present invention is not particularly limited. For example, after separately producing the component (I) and the component (II) by one-step polymerization,
Both may be mixed by a known method, or may be produced by a known polymerization method by multi-step polymerization of two or more steps. In the case of the former mixing, a known method such as a method of kneading with a single-screw or twin-screw extruder or a Banbury mixer, or a solution mixing method can be used. The latter method of multi-stage polymerization means, for example, using a plurality of reactors, for example, maintaining the reactor of the first stage under the polymerization conditions of a high molecular weight polymer corresponding to the component (I), A method for producing a polyethylene composition, in which the reactor is maintained under the polymerization conditions for the low molecular weight polymer of component (II) and the polymer produced in the first stage is continuously passed through the second stage. However, the components (I) and (II) may be produced in any reactor, and the production sequence and the number of stages are not particularly limited. In any of the above cases, the reaction form is not particularly limited, and various methods such as a slurry method, a gas phase method, a solution method, and a high pressure ion method can be used. The polymerization catalyst is also not particularly limited, and for example, a Ziegler type catalyst, a Phillips type catalyst, a Kaminsky type catalyst and the like can be used.

Particularly preferred as the catalyst is a highly active Ziegler type catalyst supported on a solid carrier, the details of which will be described below. The high activity Ziegler type catalyst is an inorganic solid support, for example, metal magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide, various alumina, silica, silica alumina, magnesium chloride, or the like, or magnesium and an element selected from silicon, aluminum and calcium. And the like, double salts, double oxides, hydrous carbonates, hydrous silicates, etc., as well as those obtained by treating or reacting these inorganic solid carriers with oxygen-containing compounds, sulfur-containing compounds, hydrocarbons, halogen-containing substances, etc. Inorganic solid carrier of the above, a transition metal compound, for example, a metal halide such as titanium, vanadium, zirconium, chromium and the like, alkoxy halides, oxides, those having supported halogen oxides are used as a solid component. Organic compounds of Group I-IV metals, preferably zinc or al Combinations of organic metal compounds of sulfonium or these further α-
Pretreated by contacting with olefin, etc., and usually has a catalytic activity of 50 g-polymer / g-catalyst · hr · kg / cm ² -olefin pressure or higher, preferably 100 g-polymer / g-catalyst · hr · kg / cm ^2- Olefin pressure or higher. Among the above, a highly active Ziegler type catalyst containing magnesium halide is particularly preferable.

In the polyethylene composition of the present invention,
High / medium / low density polyethylene, linear low density polyethylene, ultra low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid without departing from the scope of the present invention. Ethyl copolymer, other olefinic polymers such as polypropylene, rubber or the like or antioxidants, UV absorbers, light stabilizers, lubricants, antistatic agents, antiblocking agents, processing aids, color pigments, etc. An additive can be compounded and used.

[0015]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. First,
The test methods used in the present invention are shown. (1) Intrinsic viscosity [η] was measured in a decalin solution at 135 ° C. (2) Density Density gradient tube method (23
(° C). (3) Continuous temperature rising elution fractionation method (TREF) As described above, the method of L. Wild et al. Was followed. (4) Area ratio (S) by continuous temperature rising elution fractionation method As described above and in FIG. (5) Orthodichlorobenzene-soluble matter (W) at 25 ° C. 0.5 g of a sample was added to 20 ml of orthodichlorobenzene (O).
In DCB), heat at 135 ° C. for 2 hours to completely dissolve the sample and then cool to 25 ° C. in 2 hours. This solution was left overnight at 25 ° C, filtered through a Teflon filter to collect the filtrate, and the absorption of methylene asymmetric stretching vibration at a wave number of 2950 cm ^-1 was measured with an infrared spectrophotometer. The sample concentration in the filtrate is quantified by the calibration curve obtained. (6) N-value Using a Koka type flow tester (manufactured by Shimadzu Corporation), extruding from a die of 2 mmφ × 40 mm at a resin temperature of 210 ° C., and appearance at low test pressure of 20 kg / cm ² and high test pressure of 150 kg / cm ^2. The shear rate of is calculated and calculated by the following equation 3.

[Equation 3] (7) High load melt flow rate (HLMFR) Measured in accordance with JIS K6760. (Measurement temperature 190
(° C, load 21.6 kg) (8) Tensile yield strength (YTS) According to JIS K6760. (Pulling speed 50mm / mi
n, test piece thickness 2 mm) (9) Tensile impact value (TIS) Measured in accordance with ASTM D1822. (Test piece thickness 1.
5 mm) (10) Izod impact value (IIS) Based on JIS K7110, measured at -40 ° C by the following method. A sheet having a thickness of 3 mm is produced from the sample by pressing. The shape of the test piece is No. 2A. The sample is adjusted at 23 ° C. and humidity of 50% for 88 hours, held in a low temperature room controlled at −40 ° C. for about 3 hours, and then measured at −40 ° C. in the low temperature room. Five test pieces are prepared, and the average value of five measurements is used. (11) Melt tension (MT) Measured with a melt tension tester manufactured by Toyo Seiki Co., Ltd. (Measurement temperature: 190 ° C.) (12) Die swell ratio (DSR) A sample is extruded at a temperature of 210 ° C. using a high-performance flow tester, and the ratio between the strand diameter and the die inner diameter is determined.
The shear rate was measured at an extrusion rate corresponding to 100 sec ^-1 . (13) Environmental stress crack resistance (ESCR) The value of F ₅₀ of constant strain ESCR according to JIS K6760 is obtained.

<Examples 1 to 8 and Comparative Examples 1 to 8> [Production of high molecular weight polymer] A stirring type reactor having an internal volume of 50 l was used, and titanium tetrachloride was used as a solid carrier containing anhydrous magnesium chloride as one component. Using a solid catalyst supporting C and a co-catalyst of triethylaluminum (TEA), one-stage polymerization was carried out under N ₂ atmosphere under the polymerization conditions shown in Table 1 to produce high molecular weight polymers A1 to A4. Table 1 shows the physical properties of the recovered polymerization product. Among the above polymers, A1 and A2 satisfy the criteria of the present invention, but A3 and A4 deviate from the criteria of the present invention in terms of intrinsic viscosity and density, respectively. [Production of Low Molecular Weight Polymer] Using the same reactor and catalyst of the same system as in the case of the above high molecular weight polymer, one-stage polymerization was carried out under N ₂ atmosphere under the polymerization conditions shown in Table 2 to obtain a low molecular weight polymer. Coalescences B1 to B5 were produced. Table 2 shows the physical properties of the recovered polymerization product. Of the above polymers, B1, B2 and B5 satisfy the criteria of the present invention, while B3 and B4 are W respectively.
The values of and S deviate from the criteria of the present invention. [Preparation of Composition] Using the polymer, a polyethylene composition was prepared by the solution mixing method under the following blending conditions,
Tables 3 to 6 show the results of evaluation of the physical properties of the examples and the comparative examples. <Blending conditions> Atmosphere: N ₂ Solvent: Xylene (4.5 l) Amount of sample: Total 200g Temperature: 200 ° C. during between 2 hours deposition solvent: -20 ° C. Methanol (8l) washing solvent: hexane wash: Xylene Dry until odor disappears: From room temperature to 110 ° C Polymer recovery rate: Almost 100%

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

[Table 5]

[0022]

[Table 6]

Comparative Examples 9 to 13 Table 7 shows the results of evaluation of the following brands among commercially available products intended for large hollow moldings. (1) Showrex 4551H (Showa Denko KK) (2) Hi-Z 8200B (Mitsui Petrochemical Industry)
(3) Yucaron HD BZ80 (Mitsubishi Petrochemical Co., Ltd.) (4) Tonen Polyethylene B5551 (Tonen Petrochemical Co., Ltd.) (5) Novatec BR300 (Mitsubishi Kasei Co., Ltd.)

[0024]

[Table 7]

<Examples 9 and 10> A stirring type reactor having an internal volume of 70 l was used, and a solid catalyst having titanium tetrachloride supported on a solid carrier containing anhydrous magnesium chloride as a component and a triethylaluminum cocatalyst were used. Then, under the N ₂ atmosphere, the low-molecular weight components were continuously polymerized under the first-stage polymerization conditions shown in Table 6. These polymers were continuously introduced into an unreacted gas separation tank to separate unreacted gas. Subsequently, a high-molecular weight component was continuously polymerized under the second-stage polymerization conditions shown in Table 8 using a stirring reactor having an internal volume of 30 liters. The amount of the polymerization product in each stage was calculated from the heat balance, and the total amount was in agreement with the amount of the polymerization product finally recovered. Table 9 shows the measured results of the physical properties of the polymerization products recovered from the first and second stage reactors. The physical properties of the high molecular weight component produced in the second stage reactor were calculated.

[0026]

[Table 8]

[0027]

[Table 9]

<Examples 11 to 15> Using a stirred reactor having an internal volume of 30 liters and using the same catalyst as in Examples 9 and 10 under N ₂ atmosphere, the first stage polymerization conditions shown in Table 10 were used. Thus, the high molecular weight component was continuously polymerized. These polymers were continuously introduced into an unreacted gas separation tank to separate unreacted gas. Subsequently, a low molecular weight component was continuously polymerized under the second stage polymerization conditions shown in Table 10 using a stirring reactor having an internal volume of 70 liters. The amount of the polymerization product in each stage was calculated from the heat balance, and the total amount was in agreement with the amount of the polymerization product finally recovered. Table 11 shows the measured results of the physical properties of the polymerization products recovered from the first and second stage reactors. The physical properties of the low molecular weight component produced in the second stage reactor were calculated.

[0029]

[Table 10]

[0030]

[Table 11]

Particularly important relationships in each of the above tables are plotted and shown in FIGS. From these results, it is clear that the polyethylene composition of the present invention is superior in MT, DSR and IIS (-40 ° C) as compared to commercial products showing the same HLMFR. Therefore, it can be seen that the polyethylene composition is excellent in melt elasticity, flow characteristics, mechanical characteristics and the like, and particularly excellent in mechanical characteristics at low temperature.

[0032]

Industrial Applicability The polyethylene composition of the present invention is a composition having an extremely wide range of molecular weight distribution with excellent balance of melt elasticity, flow characteristics, mechanical characteristics and the like, and specifically has the following characteristics. (1) Excellent mechanical properties at low temperature such as low temperature Izod impact value and cold resistance. (2) Since it has excellent melt elasticity such as melt tension and die swell ratio, and flow characteristics, it has good moldability such as high-speed moldability. As a result of having the above-mentioned advantages, it is used for various films, sheets, pipes, hollow containers, various coating materials, foaming materials, etc., but since it has extremely excellent melt elasticity, it is a composition for large hollow containers such as gasoline tanks. Is useful as

[Brief description of drawings]

[Figure 1] Elution temperature by continuous temperature elution fractionation (TREF)-
It is a figure which shows the relationship of an elution amount.

Figure 2: High load melt flow rate (HLMFR)
FIG. 6 is a diagram showing a relationship of melt tension.

FIG. 3 is a diagram showing a relationship of HLMFR-die swell ratio.

FIG. 4 is a diagram showing a relationship between HLMFR and Izod impact value (−40 ° C.).

Claims (3)

[Claims] 1. (I) 1-50% by weight of a high molecular weight ethylene homopolymer or ethylene / α-olefin copolymer satisfying the following (a) and (b), (a) intrinsic viscosity (η ₁ ). 9-45 dl / g (b) Density (d ₁ ) 0.890 to 0.935 g / cm ³ and (II) Low molecular weight ethylene homopolymer or ethylene / α- which satisfies the following (c) to (f) Olefin copolymer 99 to 50% by weight (c) Intrinsic viscosity (η ₂ ) 0.3 to 3.0 dl / g (d) Density (d ₂ ) 0.890 to 0.980 g / cm ³ (e) Continuous increase In the elution temperature-elution amount curve by the hot elution fractionation method, the ratio S (Ib / Ib / of the area Ib at the elution temperature of 25 to 90 ° C. to the area Ia under the curve at the elution temperature of 90 ° C. or more
Ia) is less than or equal to S ₁ calculated from the following equation, S ₁ = 20η ₂ ⁻¹ exp [−50 (d ₂ − 0.900)] (f) 25 ° C. ortho-dichlorobenzene soluble content W weight% is calculated from the following equation. that W ₁ or ^{_{less, W 1 = 100η 2 -0.5 exp}} [- 50η 2 0.5 (d 2 - 0.900)] a mixture consisting of, and the intrinsic viscosity of the mixture (eta) is 1~10dl / g, a density ( d) 0.890 to 0.97
N-value calculated from 0 g / cm ³ and the following equation 1 is 1.7-
A polyethylene composition which is 3.0. [Equation 1] 2. The high molecular weight ethylene homopolymer or ethylene / α-olefin copolymer and / or the low molecular weight ethylene homopolymer or ethylene / α-olefin.
The polyethylene composition according to claim 1, wherein the olefin copolymer is produced with a highly active Ziegler-based catalyst containing a magnesium halide compound. 3. The ethylene / α-olefin copolymer having a high molecular weight and the ethylene / α-olefin copolymer having a low molecular weight are copolymers of ethylene and an α-olefin having 3 to 18 carbon atoms. The polyethylene composition according to claim 1 or 2, characterized in that.