JP3372057B2 - Ethylene polymer composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to melt elasticity (melt tension, die swell ratio, etc.), flow properties (working properties, etc.), mechanical properties (impact resistance, tensile strength). Ethylene polymer composition with excellent molecular weight distribution
Particularly, it relates to an ethylene polymer composition which is excellent in flow characteristics and mechanical characteristics at low temperatures, and has a high melt tension and a large die swell ratio, and is suitable for large hollow molded articles such as gasoline tanks, extruded articles such as large diameter pipes and the like. . 2. Description of the Related Art Conventionally, there has been reported a method for widening the molecular weight distribution of an ethylene / α-olefin copolymer for the purpose of improving flow characteristics (for example, Japanese Patent Application Laid-Open No. 57-21409, Japanese Patent Publication No. Sho. However, simply increasing the molecular weight distribution in this manner does not improve the melt elasticity and mechanical properties, particularly the mechanical properties at low temperatures, but rather greatly reduces them. Regarding the improvement of mechanical properties and flow properties, the degree of short chain branching of the high molecular weight component of the ethylene / α-olefin copolymer composed of the high molecular weight component and the low molecular weight component is specified, and Attempts have been made to introduce many branches to improve not only mechanical properties and fluidity, but also environmental stress crack resistance (ESCR) (Japanese Patent Application Laid-Open No. 54-100444, Japanese Patent Publication No. 64-7096).
No.). However, even in these, the mechanical properties, especially the mechanical properties at low temperature and the melt elasticity are not satisfactory. Furthermore, in JP-A-2-305581,
For the purpose of improving impact resistance, ESCR, and pinch-off fusing properties, a method has been proposed to specify the polymerization conditions of the catalyst and the two-stage polymerization. However, this method has a slight improvement in terms of ESCR and melt elasticity. Although seen, it is insufficient to improve the mechanical properties, especially at low temperatures. In addition, as a polyethylene composition for hollow molding, improved drawdown resistance, die swell and ESCR (Japanese Patent Application Laid-Open No.
9-89341, JP-A-60-20946, etc.)
And a three-stage polymerization method has been proposed as a method for improving the disadvantages of the two-stage polymerization method (JP-B-59-1072).
No. 4, JP-A Nos. 62-25105 and 62-25106
No. 62-25107, No. 62-25108,
No. 62-25109, etc.). Also in these, the improvement of the melt elasticity and the flow characteristics is still insufficient, and particularly no improvement in the mechanical characteristics at low temperatures. In view of the above, the present invention has been made in view of the above points, and has been made in view of the following points: melt elasticity (melt tension, die swell ratio, etc.)
An ethylene polymer composition with an excellent balance of various physical properties such as flow properties (processing properties, etc.) and mechanical properties (impact resistance, tensile strength, etc.) and an extremely wide molecular weight distribution. It is an object of the present invention to provide a composition suitable for a large-sized hollow molded article such as a gasoline tank, an extruded molded article such as a large-diameter pipe, etc. because of its excellent mechanical properties and high melt tension and die swell ratio. Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned object, and have found that the distribution of ultra-high molecular weight components and high molecular weight components and the distribution of short-chain branches between molecules is extremely high. Wide specific ethylene / α-olefin copolymer and specific ethylene / α with extremely wide short-chain branch distribution between molecules
-By blending a low molecular weight component consisting of an olefin copolymer or an ethylene homopolymer having no short-chain branching, it is excellent in balance of various physical properties such as melt elasticity, flow properties, and mechanical properties, especially flow properties and low temperature. The present inventors have found that an ethylene polymer composition having excellent mechanical properties can be obtained, and have reached the present invention. That is, the present invention provides (I)
Ultrahigh molecular weight ethylene homopolymer or ethylene / α-olefin copolymer 1 to 50 satisfying (a) and (b)
(A) intrinsic viscosity (η ₁ ) 9 to 45 dl / g, (b) density (d ₁ ) 0.890 to 0.935 g / cm ³ , (II) high activity supported on a solid carrier Ziegler type
Polymerized with a catalyst, ethylene homopolymer or ethylene / α-olefin copolymer 5 satisfying the following (c) to (f):
94% 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 heating elution fractionation In the elution temperature-elution amount curve obtained by the method, the ratio S (Ib / Ib / Ib) of the area Ib at the elution temperature of 25 to 90 ° C. to the area Ia under 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. orthodichlorobenzene soluble matter W weight% is calculated from the following equation W ₁ or less, W ₁ = 100η ₂ ^−0.5 exp [−50η ₂ ^0.5 (d ₂ −0.900)], and (III) a highly active Ziegler supported on a solid support.
Of copolymerized ethylene and α-olefin having 3 to 18 carbon atoms satisfying the following (g) to (j) and polymerized with a type catalyst.
(G) Intrinsic viscosity (η ₃ ) 1.2 dl / g or more and less than 9.0 dl / g, (h) Density (d ₃ ) 0.890 to 0.940 g / cm ³ , (i) Continuous In the elution temperature-elution amount curve obtained by the elevated temperature elution fractionation method, the ratio S (Ib / Ib / Ib / Ib) of the area Ib at the elution temperature of 25 to 90 ° C. to the area Ia under the elution temperature of 90 ° C. or more.
S ₂ below Ia) is calculated from the following ^{_{equation, S 2 = 20η 3 -1 exp}} [-50 (d 3 -0.900)] (j) 25 ℃ orthodichlorobenzene soluble content W wt% is calculated from the following equation that W ₂ or more, made of _{W 2 = 20exp (-η 3)} , and wherein component (I), the sum is 100% by weight of (II) and (III), of each component (I) ~ (III) A mixture having intrinsic viscosity different from each other, the intrinsic viscosity of the mixture is 1.0 to 6.0 dl / g, and the density is 0.890 to 800
The present invention provides an ethylene polymer composition having an N-value of 1.7 to 3.0 calculated from 0.970 g / cm ³ and the following equation (2). [0005] Hereinafter, the contents of the present invention will be described in detail. The ultrahigh 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 3 to 18 carbon atoms. Particularly, those having 4 to 10 carbon atoms are preferable from the viewpoint of mechanical properties. Specifically, 1-butene, 1-pentene,
Examples thereof include 1-hexene, 4-methyl-1-pentene, 1-octene, 1-nonene, and 1-decene. Note that α-
Two or more olefins may be used in combination. [0007] The ultrahigh molecular weight component (I), ethylene homopolymer or ethylene / α-olefin copolymer,
(a) The intrinsic viscosity (η ₁ ) is 9 to 45 dl / g, preferably 10 to 45 dl / g.
40 dl / g, more preferably 12 to 40 dl / g is used. In eta ₁ is less than 9 dl / g, the melt elasticity and mechanical properties of the resulting composition poor, and when it exceeds 45dl / g, moldability such as molded article surface roughness and fisheyes occurs decreases . 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. If d ₁ is less than 0.890 g / cm ³ , it is not preferable because the production is difficult and the resulting composition becomes sticky. On the other hand, if d ₁ exceeds 0.935 g / cm ³ , the mechanical properties of the composition, especially at low temperatures, are undesirably reduced. The component (II) of the present invention is supported on a solid carrier.
And an ethylene homopolymer or an ethylene / α-olefin copolymer polymerized with a high activity Ziegler catalyst . As the α-olefin of the ethylene / α-olefin copolymer, as in the case of the component (I), the α-olefin has 3 to 1 carbon atoms.
8 are used, preferably having 4 to 10 carbon atoms, and in particular, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-
Nonene, 1-decene, and the like are preferred in terms of mechanical properties and the like. Note that two or more α-olefins may be used in combination. The component (II) has a (c) intrinsic viscosity (η ₂ ) in the range of 0.3 to 3.0 dl / g, preferably 0.6 to 3.0 dl / g.
It is in the range of 0 dl / g. When η ₂ is less than 0.3 dl / g, the mechanical properties of the obtained composition, especially at low temperatures, are inferior. On the other hand, when η ₂ exceeds 3.0 dl / g, the flow properties of the composition are deteriorated. Not preferred. The components (II) (d) Density (d ₂₎ is in the range of 0.890~0.980g / cm ^3, preferably in the range of 0.900~0.975g / cm ³ is used.
If d ₂ is less than 0.890 g / cm ³ , it is not preferable because the production is difficult and the resulting composition becomes sticky. On the other hand, when it exceeds 0.980 g / cm ³ , not only is production difficult, but also mechanical properties of the obtained composition are deteriorated, which is similarly unfavorable. The above-mentioned component (II) used in the present invention
The condition of (e) utilizes the property that a high branching component containing a large amount of short-chain branching dissolves in a solvent at a low temperature, but a low branching degree component having few short-chain branching does not dissolve in a solvent unless the temperature is high. , The branch distribution is defined quantitatively. In other words, a continuous heating elution fractionation method by L. Wild et al. (Temperature Rising Elution Fract
ionation (TREF); Journal of Polymer Science: Polyme
r Physics Edition, Vol. 20, 441-455 (1982)), in the elution temperature-elution amount curve, between the area Ia under the elution temperature of 90 ° C or higher and the same area Ib at the elution temperature of 25 to 90 ° C. It is necessary that a specific relationship 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 = 20η ₂ ^-1 exp [−50 (d ₂ −0.900)] When the value of S exceeds S ₁ , the branch distribution becomes almost uniform, resulting in poor mechanical properties, especially at low temperatures. Therefore, the highly effective high branching degree component is relatively reduced, which is not preferable. (F) 25 ° C. of the component (II) used in the present invention
Orthodichlorobenzene-soluble matter, to the extent that the elution temperature is too low to be quantified by the above-mentioned continuous heating elution fractionation method,
It represents the amount of a component having a very 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 low molecular weight components that are not useful, and it is necessary to eliminate these low molecular weight components as much as possible. To this end, the soluble content W wt% should be less than W ₁ obtained from the following equation. Preferably at W ₃ below. In ^{_{W 1 = 100η 2 -0.5 exp [}} -50η 2 0.5 (d 2 -0.900)] W 3 = 90η 2 -0.5 exp [-50η 2 0.5 (d 2 -0.900)] value of W is W ₁ or more, very This indicates that there is a low molecular weight component that is not useful in addition to the component having a large amount of branching, and the mechanical properties, particularly at low temperatures, are inferior. The component (III) of the present invention is supported on a solid carrier.
The a ethylene <br/> emissions · alpha-olefin copolymer polymerized with Ziegler-type catalyst having a high activity, as in the case of component (I) and (II), ethylene and having from 3 to 18 carbon atoms Α
-A copolymer with an olefin, preferably one having 4 to 10 carbon atoms is preferred in terms of mechanical properties and the like. Specifically, 1-butene, 1-pentene, 1-hexene, 4-
Methyl-1-pentene, 1-octene, 1-nonene, 1
-Decene and the like. Note that two or more α-olefins may be used in combination. The intrinsic viscosity (η ₃ ) of component (III) (g) ranges from 1.2 dl / g to less than 9.0 dl / g, preferably from 1.4 to 8.5 dl / g. More preferably, 1.6 to 8.0.
It is in the range of dl / g. When η ₃ is less than 1.2 dl / g, the obtained composition has inferior melt elasticity and mechanical properties.
If it exceeds l / g, the formability of the molded product will be reduced, such as surface roughness and fish eyes. The component (III) has a (h) density (d ₃ ) of 0.3.
Range is used 890~0.940g / cm ^3, preferably in the range of 0.900~0.935g / cm ^3. d ₃ 0.8
If the amount is less than 90 g / cm ³ , it is not preferable because the production is difficult and the obtained composition becomes sticky. On the other hand, when it exceeds 0.940 g / cm ³ , the mechanical properties are deteriorated. The component (III) used in the present invention comprises the component (i)
As shown in (e) of the component (II), the area ratio S of the elution temperature-elution amount curve in the continuous heating elution fractionation method as described above
= Ib / Ia must be less than or equal to S ₂ obtained from the following equation. S ₂ = 20η ₃ ^-1 exp [−50 (d ₃ −0.900)] When the value of S exceeds S ₂ , the branch distribution becomes almost uniform, and as a result, the mechanical characteristics, especially at low temperatures, Therefore, the highly effective high branching degree component is relatively reduced, which is not preferable. (J) 25 of the component (III) used in the present invention
As described above, the orthodichlorobenzene-soluble component is a component having an extremely high branching degree such that the elution temperature is too low to be quantified by the above-mentioned continuous temperature-elution fractionation method. It is necessary to be. That is, the soluble W content by weight must be equal to or greater than W ₂ obtained from the following equation. Preferably it is W ₄ or more. W ₂ = 20 exp (−η ₃ ) W ₄ = 22 exp (−η ₃ ) When the value of W is less than W ₂ , the high branching degree component which is extremely effective for mechanical properties, particularly, mechanical properties at low temperatures is too small. Which is not preferred as above. In the present invention, the proportions of the components (I), (II) and (III) are 1 to 50% by weight of the component (I), 5 to 94% by weight of the component (II) and 5 to 94% by weight of the component (III). weight%
And preferably (I) 5 to 40% by weight, (I)
I) 5 to 90% by weight and (III) 5 to 90% by weight, provided that the total amount of components (I), (II) and (III) is 1%
It is 00% by weight, and these compounding ratios are selected according to the required performance for the composition. Since the component (I) plays an important role in the present invention, it is preferable to select the composition ratio of the composition in consideration of the characteristics of the component (I). When the amount of the component (I) is less than 1% by weight, the melt elasticity and the mechanical properties, especially at low temperatures, are not sufficient, while when it exceeds 50% by weight, the flow properties become poor. In addition, component (I) to component (IV)
It is important that the intrinsic viscosities of each are different from each other,
If this is not satisfied, it is not possible to improve the low-temperature mechanical properties, which is one of the objects of the present invention. The ethylene polymer composition of the present invention is obtained by blending the components (I), (II) and (III) as described above, and the intrinsic viscosity of the composition is 1.0 to 6.0 dl /. g
Preferably it is 1.5-5.0 dl / g. Intrinsic viscosity is 1.0
If it is less than dl / g, the melt viscosity and mechanical properties, especially at low temperatures, are insufficient. On the other hand, if it exceeds 6.0 dl / g, the flow properties are low, so neither is preferred. Density of the composition is 0.890~0.970g / cm ^3, preferably 0.900~0.970g / cm ^3.
If the density is less than 0.890 g / cm ^3, it is difficult to produce, and the composition becomes sticky. If the density exceeds 0.970 g / cm ³ , the mechanical properties are lowered. Further, it is necessary that the N-value of the composition is 1.7 to 3.0, preferably 1.7 to 2.8. If the N-value is less than 1.7, the high-speed moldability is low, and if it exceeds 3.0, melt fracture tends to occur. In the method for producing the ethylene polymer composition of the present invention , each component of the composition satisfies specific conditions.
There is no particular limitation as long as it is For example, component (I),
After each of the component (II) and the component (III) is produced independently by one-stage polymerization, both may be mixed by a known method,
Alternatively, it may be produced by a known polymerization method by multi-stage polymerization of two or more stages. In the case of producing by 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. Two-stage polymerization or
The composition produced by the multi-stage polymerization method
The composition obtained by individually polymerizing the components and then blending is
All have the same properties. The latter method using multi-stage polymerization is a method in which polymerization is performed using a plurality of reactors. For example, in the case of two-stage polymerization, the first reactor is charged with the component (I). While maintaining the polymerization conditions to be produced, the second stage reactor is maintained under the polymerization conditions of component (II), the polymer produced in the first stage is continuously passed through the second stage, and the ethylene polymer composition Can be manufactured. In this case, the components (I) and (II) may be produced in any reactor,
The number of stages is not particularly limited. In any of the above cases, the reaction mode is not particularly limited, and the slurry method,
Various methods such as a gas phase method, a solution method, and a high pressure ion method can be used. In these methods, the reaction temperature, pressure, etc.
Any known operating conditions include, for example, chemical engineering, 47,
[5] (1983) Fujita, Ushida, p329 and Komba
-Tech (1990.1) Doi, p77
You. In addition, components used in Examples and Comparative Examples described later.
B1 to B3 and C1 which are minutes (II) or (III)
To C7, the amount of comonomer supplied
When the polymerization is reduced, the high branching degree component decreases, and W
Values tend to be small, and the polymerization temperature and pressure
If the value is smaller, the branching degree distribution becomes narrower, so the S value becomes larger and the W value becomes larger.
Tend to be smaller. The polymerization catalyst is , for example, titanium and / or
Or Ziegler type mainly composed of transition metals such as vanadium
A catalyst can be used. In particular, components (II) and (I
It is necessary that the catalyst for producing II) is a highly active Ziegler-type catalyst supported on a solid support, and the details thereof will be described below. The highly active Ziegler type catalyst is prepared from an inorganic solid carrier such as metal magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide, various aluminas, silica, silica alumina, magnesium chloride or the like, or from magnesium and silicon, aluminum or calcium. Double salts, double oxides, hydrated carbonates, hydrated silicates, and the like containing the selected element, and further, these inorganic solid carriers are treated or reacted with oxygen-containing compounds, sulfur-containing compounds, hydrocarbons, and halogen-containing substances. An inorganic solid carrier such as a support, a transition metal compound, for example, titanium, vanadium, zirconium, chromium and other metal halides, alkoxy halides, oxides, halide oxides and the like are used as solid components. And organic compounds, preferably subgroups, of Group I-IV metals. Or Combinations of aluminum organometallic compounds of, or of these further α-
The catalyst is pretreated by contact with an olefin and has a catalytic activity of usually 50 g-polymer / g-catalyst · hr · kg / cm ² -olefin pressure or more, preferably 100 g-polymer / g-catalyst · hr · kg / cm ^2- olefin pressure. Among these, a highly active Ziegler-type catalyst containing a magnesium halide is particularly preferred. In the ethylene polymer composition of the present invention, other olefin polymers, rubbers or antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, etc., without departing from the scope of the present invention. Known additives such as anti-fogging agents, anti-blocking agents, processing aids, coloring pigments, crosslinking agents, foaming agents, inorganic and organic fillers, and flame retardants can be used. Next, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. First,
1 shows a test method used in the present invention. (1) The intrinsic viscosity was measured at 135 ° C. in a decalin solution. (2) Density gradient tube method according to JIS K6760 (23
° C). (3) Continuous heating elution fractionation method (TREF) As described above, the method of L. Wild et al. Was used. Details of the measuring method are as follows. [Measurement Method] Into a 8.5-liter stainless steel column filled with Celite 545, 5 ml of an orthodichlorobenzene solution prepared by heating and dissolving a sample at 135 ° C. to a concentration of 0.05% by weight was injected. After 4 ℃ / min
Cool at 25 ° C. to a temperature of 25 ° C. and deposit the sample on the Celite surface. Next, while flowing orthodichlorobenzene through this column at a constant rate of 1 ml / min, the temperature is raised at a constant rate of 50 ° C./hr, and the samples are sequentially eluted. At this time, with respect to the sample eluted in the solvent, the absorption at a wave number of 2925 cm ⁻¹ of asymmetric stretching vibration of methylene was detected by an infrared detector,
By recording, the relationship between the elution temperature and the elution amount, that is, the composition distribution is obtained. (4) Area ratio (S) by continuous heating elution fractionation method As described above and 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. After leaving this solution at 25 ° C. overnight, the solution was filtered through a Teflon filter, and the filtrate was collected. The absorption at a wave number of 2950 cm ⁻¹ of asymmetric stretching vibration of methylene was measured with an infrared spectrophotometer. The sample concentration in the filtrate is quantified using the calibration curve obtained. (6) Extrusion from a 2 mmφ × 40 mm die at a resin temperature of 210 ° C. using a high N-value flow tester (manufactured by Shimadzu Corporation), apparent at a low test pressure of 20 kg / cm ² and a high test pressure of 150 kg / cm ² Is calculated by the following equation (3). (Equation 3) (7) High load melt flow rate (HLMFR) Measured according to JIS K6760. (Measurement temperature 190
(° C, load: 21.6 kg) (8) Tensile yield strength (YTS) According to JIS K6760. (Pulling speed 50mm / mi
(n, specimen thickness 2 mm) (9) Tensile impact value (TIS) Measured in accordance with ASTM D1822. (Specimen thickness 1.
(10) Izod impact value (IIS) Measured at -40 ° C according to JIS K7110 by the following method. A 3 mm-thick sheet is prepared from the sample by pressing. The shape of the test piece is No. 2A. All samples were prepared at 23 ° C. and 50% humidity for 88 hours, then kept 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 an average value of five measurements is used. (11) Melt tension (MT) Measured by a melt tension tester manufactured by Toyo Seiki Co., Ltd. (Measurement temperature 190 ° C.) (12) Die swell ratio (DSR) The sample is extruded at a temperature of 210 ° C. using a Koka type flow tester, and the ratio of the diameter of the strand to the inner diameter of the die is determined.
It was measured at an extrusion rate corresponding to a shear rate of 100 sec ^-1 . (13) Critical shear rate (γc) Measured by a capillary rheometer manufactured by INTESCO Corporation. (Measurement temperature 190 ° C.) (14) determines the value of F ₅₀ of constant strain ESCR by environmental stress crack resistance (ESCR) JIS K6760. [Production of Components (I), (II) and (III)] First, titanium tetrachloride is supported on a solid carrier containing anhydrous magnesium chloride as a component using a stirred reactor having an internal volume of 50 liters. Solid catalyst and triethylaluminum (T
Using the co-catalyst of EA), one-stage polymerization is carried out under a nitrogen atmosphere, and the polymers A1 and A2 of the component (I) and the polymers B1 to B2 of the component (II) are converted into a highly active Ziegler catalyst.
The polymer B3 was produced using a conventional catalyst .
Table 1 shows the polymerization conditions and the physical properties of the obtained polymer. [Table 1] Using a stirred reactor having an internal volume of 70 liters, and using the same catalyst system as described above, one-stage polymerization was carried out continuously under the polymerization conditions shown in Table 2.
C3 was produced. At this time, the polymerization pressure of the reactor was adjusted to 8.8 total pressure.
Polymerization was carried out while keeping the liquid volume at リ ッ ト ル 9.2 kg / cm ² G and the liquid volume at 50 liters. Table 2 shows the results of evaluating the physical properties of these polymers. [Table 2] Next, using an autoclave having an internal volume of 2 liters and a catalyst similar to the above, under an atmosphere of nitrogen under a nitrogen atmosphere.
Step polymerization was carried out to produce polymers C4 to C7 of component (III). Table 3 shows the polymerization conditions and physical properties of the obtained polymer. [Table 3] [Preparation of Composition] Of the above polymers, component (I) and component (II) were mixed and prepared by a solution mixing method under the following blend conditions. <Blend conditions> Atmosphere: Nitrogen solvent: Xylene (4.5 L) Sample amount: Total 200 g Temperature: 200 C Time: 2 hours Precipitation solvent: -20 C Methanol (8 L) Cleaning solvent: Hexane washing Cleaning: Drying until xylene odor disappears: Polymer recovery from room temperature to 110 ° C .: almost 100% Further, the above mixture and the polymer of component (III) were mixed under a nitrogen atmosphere in a total sample amount of 70 g, a rotation speed of 20 rpm, and a kneading time. The mixture was mixed at a kneading temperature of 160 ° C. for 7 minutes to obtain compositions of Examples and Comparative Examples. <Examples 1 to 6> Table 4 shows the proportions of the compositions of the examples and the evaluation results of the physical properties. [Table 4] <Comparative Examples 1 to 6> Table 5 shows the proportions of the compositions of Comparative Examples and evaluation results of physical properties. [Table 5] Next, FIG. 2 is a schematic diagram in which a molecular weight is further added as a parameter to the elution temperature-elution amount curve by TREF shown in FIG. 1 and the elution amount is represented by a contour line.
In the same figure, for example, comparing the example and the comparative example with respect to the range where the molecular weight is 10,000 or more, the composition of the example has a lower elution temperature in a region having a larger molecular weight than the composition of the comparative example. It can be seen that the component, that is, a component having a large number of short-chain branches (orthodichlorobenzene-soluble component at 25 ° C.) is contained in a larger amount. It is estimated that this component is a major factor in improving the low temperature mechanical properties and ESCR of the composition of the present invention. The ethylene polymer composition of the present invention comprises a specific ethylene / α-olefin copolymer which is an ultrahigh molecular weight component or a high molecular weight component and has a very wide distribution of short-chain branches between molecules. And a low molecular weight component comprising a specific ethylene / α-olefin copolymer or an ethylene homopolymer having no short-chain branching in which the distribution of short-chain branches between molecules is extremely wide. It is a composition with an extremely wide molecular weight distribution that is excellent in balance between 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 is excellent in melt elasticity such as melt tension and die swell ratio and flow characteristics such as critical shear rate,
Good moldability such as high-speed moldability. As a result of having the above advantages, it is used for various films, sheets, pipes, hollow containers, various coating materials, foamed materials, etc., but since it has particularly excellent melt elasticity, it is a composition for large hollow containers such as gasoline tanks. Useful as

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the relationship between the elution temperature and the amount of elution by a continuous heating elution fractionation method (TREF). FIG. 2 is an elution temperature-molecular weight-elution amount contour map of a composition. (A) Example 1, (b) Comparative Example 1

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Claims (1)

(I) 1 to 50% by weight of an ultrahigh molecular weight ethylene homopolymer or ethylene / α-olefin copolymer satisfying the following (a) and (b): (A) intrinsic viscosity (η ₁ ) 9 to 45 dl / g, (b) density (d ₁ ) 0.890 to 0.935 g / cm ³ , (II) high activity Ziegler type supported on a solid support
Polymerized with a catalyst, ethylene homopolymer or ethylene / α-olefin copolymer 5 satisfying the following (c) to (f):
94% 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 heating elution fractionation In the elution temperature-elution amount curve obtained by the method, the ratio S (Ib / Ib / Ib) of the area Ib at the elution temperature of 25 to 90 ° C. to the area Ia under 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. orthodichlorobenzene soluble matter W weight% is calculated from the following equation W ₁ or less, W ₁ = 100η ₂ ^−0.5 exp [−50η ₂ ^0.5 (d ₂ −0.900)], and (III) a highly active Ziegler supported on a solid support.
Of copolymerized ethylene and α-olefin having 3 to 18 carbon atoms satisfying the following (g) to (j) and polymerized with a type catalyst.
(G) Intrinsic viscosity (η ₃ ) 1.2 dl / g or more and less than 9.0 dl / g, (h) Density (d ₃ ) 0.890 to 0.940 g / cm ³ , (i) Continuous In the elution temperature-elution amount curve obtained by the elevated temperature elution fractionation method, the ratio S (Ib / Ib / Ib / Ib) of the area Ib at the elution temperature of 25 to 90 ° C. to the area Ia under the elution temperature of 90 ° C. or more.
S ₂ below Ia) is calculated from the following ^{_{equation, S 2 = 20η 3 -1 exp}} [-50 (d 3 -0.900)] (j) 25 ℃ orthodichlorobenzene soluble content W wt% is calculated from the following equation that W ₂ or more, made of _{W 2 = 20exp (-η 3)} , and wherein component (I), the sum is 100% by weight of (II) and (III), of each component (I) ~ (III) A mixture having intrinsic viscosity different from each other, the intrinsic viscosity of the mixture is 1.0 to 6.0 dl / g, and the density is 0.890 to 800
An ethylene polymer composition having an N-value of 1.7 to 3.0 calculated from 0.970 g / cm ³ and the following equation (1). (Equation 1)