Ethylene-based polymer composition and pipe made therefrom

Abstract

This invention provides an ethylene-based polymer composition suitable for polyethylene pipes that combines the performance required for PE112 (MRS 11.2 MPa or higher), which is necessary for higher creep strength, with excellent moldability and low sagging properties. [Solution] An ethylene-based polymer composition containing 40-60% by mass of an ethylene homopolymer (A) whose MFR (MFR2) measured at a temperature of 190°C and a load of 2.16 kg is in the range of 100-600 g / 10 min, and 60-40% by mass of a copolymer (B) of ethylene and an α-olefin having 4 or more carbon atoms [ethylene-α-olefin copolymer (B)], which satisfies the following requirements (i) to (iii). (i) Density of 940-960 kg / m³ 3 It is within the range. (ii) The amount of components with logM ≥ 7 measured by GPC is in the range of 0.35 to 0.80%. (iii) The amount of components with logM ≤ 3 measured by GPC is 1.85% or less.

Description

Technical Field

[0001] The present invention relates to an ethylene-based polymer composition suitable for obtaining an extruded molded article such as a pipe having excellent moldability and more excellent long-term performance, and a pipe made thereof.

Background Art

[0002] Ethylene-based polymers are molded by various molding methods and are used in a wide range of applications. For example, high-pressure low-density polyethylene polymerized by a high-pressure radical polymerization method is known to have long-chain branches and excellent processability. A linear low-density ethylene-α-olefin copolymer obtained by polymerizing ethylene and an α-olefin using a Ziegler-Natta catalyst is known to be excellent in mechanical strengths such as tensile strength, tear strength, and impact strength, and long-term durability represented by environmental stress cracking (ESCR), hot internal pressure creep characteristics of pipes, and slow crack growth characteristics (SCG). A linear low-density ethylene-α-olefin copolymer obtained by polymerizing ethylene and an α-olefin using a metallocene catalyst is known to be extremely excellent in impact strength and ESCR. High-density polyethylene is obtained by copolymerizing ethylene alone or ethylene and an α-olefin using a Ziegler-Natta catalyst, a chromium catalyst, a metallocene catalyst, etc., and is known to be excellent in rigidity and heat resistance.

[0003] And, since a single ethylene-based polymer cannot satisfy the physical properties required depending on the application, many methods of mixing two kinds of ethylene-based polymers having different MFR, density, etc. have been proposed (for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] While the properties of conventional polyethylene pipes are sufficient in many cases, higher pressure resistance is required for applications demanding greater pressure resistance, such as pipes subjected to internal fluid pressure over long and / or short periods. Currently, the design stress grade PE100 (MRS 10.0 MPa), which is determined by obtaining the MRS from the ISO 12162 classification table based on the lower confidence limits determined according to ISO 9080, is common.

[0006] The object of the present invention is to obtain an ethylene-based polymer composition suitable for polyethylene pipes that achieves both the performance of PE112 (MRS 11.2 MPa or more and less than 12.5 MPa) or even higher, such as PE125 (MRS 12.5 MPa or more and less than 14.0 MPa), which requires higher creep strength, and excellent moldability and low sagging properties. [Means for solving the problem]

[0007] The present invention relates to the following [1] to

[12] .

[0008] [1] An ethylene-based polymer composition comprising 40-60% by mass of an ethylene homopolymer (A) having an MFR (MFR2) in the range of 100-600 g / 10 min measured at a temperature of 190°C and a load of 2.16 kg, and 60-40% by mass of a copolymer (B) of ethylene and an α-olefin having 4 or more carbon atoms [ethylene-α-olefin copolymer (B)] [provided that the total amount of (A) + (B) is 100% by mass], characterized in that it satisfies the following requirements (i) to (iii). (i) Density of 940-960 kg / m³ 3 It is within the range. (ii) The amount of components with logM ≥ 7 measured by GPC is in the range of 0.35 to 0.80%. (iii) The amount of components with logM ≤ 3 measured by GPC is 1.85% or less.

[0009] [2] The ethylene polymer composition according to item [1], characterized in that the α-olefin having 4 or more carbon atoms is 1-butene or 1-hexene.

[0010] [3] The ethylene-based polymer composition according to item [1] or [2], characterized in that the ethylene-α-olefin copolymer (B) has an intrinsic viscosity [η] in the range of 7.0 to 14.0 dl / g.

[0011] [4] An ethylene-based polymer composition according to any one of items [1] to [3], characterized in that the ethylene-based polymer composition has an MFR (MFR5) measured at a temperature of 190°C and a load of 5 kg in the range of 0.03 to 0.3 g / 10 min.

[0012] [5] An ethylene-based polymer composition according to any one of the items [1] to [4], wherein the molecular weight distribution (Mw / Mn) measured by GPC is in the range of 30 to 70.

[0013] [6] An ethylene-based polymer composition according to any one of items [1] to [5], wherein an ethylene homopolymer (A) and an ethylene-α-olefin copolymer (B) are polymerized using a Ziegler-Natta catalyst.

[0014] [7] A pipe comprising an ethylene-based polymer composition as described in any one of items [1] to [6].

[0015] [8] The pipe according to item [7], characterized in that the pipe simultaneously satisfies (a) to (d) below in a hot internal pressure creep test measured in accordance with ISO 1167. (a) The fracture time at a test temperature of 20°C and a test circumferential stress of 12.7 MPa is 500 hours or more. (b) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.3 MPa is 100 hours or more. (c) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.1 MPa is 1,000 hours or more. (d) The fracture time at a test temperature of 80°C and a test circumferential stress of 5.7 MPa is 3,000 hours or more.

[0016] [9] The pipe according to item [7] or [8], characterized in that an ethylene polymer composition is provided with 0.01 to 3 parts by mass of one or more pigments selected from titanium dioxide, titanium yellow, phthalocyanine blue, isoindolinone, quinacridone compounds, condensed azo compounds, ultramarine, and cobalt blue added to 100 parts by mass of the composition.

[0017]

[10] An ethylene-based polymer composition comprising an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, satisfying the following requirements (i) to (vi). (i) Density of 940-960 kg / m³ 3 It is within the range. (ii) The amount of components with logM ≥ 7 measured by GPC is in the range of 0.35 to 0.80%. (iii) The amount of components with logM ≤ 3 measured by GPC is 1.85% or less. (iv) The MFR (MFR5) measured at a temperature of 190°C and a load of 5 kg is in the range of 0.03 to 0.3 g / 10 min. (v) The molecular weight distribution (Mw / Mn) measured by GPC is in the range of 30 to 70. (vi) The resulting pipe satisfies the following conditions (a) to (d) simultaneously in a hot internal pressure creep test measured in accordance with ISO 1167. (a) The fracture time at a test temperature of 20°C and a test circumferential stress of 12.7 MPa is 500 hours or more. (b) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.3 MPa is 100 hours or more. (c) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.1 MPa is 1,000 hours or more. (d) The fracture time at a test temperature of 80°C and a test circumferential stress of 5.7 MPa is 3,000 hours or more.

[0018]

[11] Furthermore, the ethylene polymer composition described in item

[10] satisfies the following requirement (vii). (vii) The chart measured by GPC shows bimodality, and the content ratio of low molecular weight components to high molecular weight components, determined by peak separation, is in the range of 40:60 to 60:40.

[0019]

[12] The ethylene-based polymer composition according to item

[11] , wherein the low molecular weight component consists of an ethylene homopolymer, and the high molecular weight component consists of a copolymer of ethylene and an α-olefin having 4 or more carbon atoms. [Effects of the Invention]

[0020] The ethylene-based polymer composition of the present invention exhibits excellent long-term creep strength and pipe moldability. Pipes using the ethylene-based polymer composition of the present invention have excellent long-term creep strength, achieving a performance of MRS 11.2 MPa or higher (PE112) as classified according to ISO 9080 and 12162. Due to its moderate fluidity, it does not impair extrusion during molding and exhibits excellent moldability and low sagging properties.

[0021] Pipes made from the ethylene-based polymer composition of the present invention are suitable for water pipes, gas pipes, and the like. [Modes for carrying out the invention]

[0022] The following describes specific embodiments of the present invention in detail. However, the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention. In this specification, unless otherwise specified, the term "polymer" is used to include homopolymers and copolymers.

[0023] <Ethylene homopolymer (A)> One of the components constituting the ethylene-based polymer composition of the present invention is an ethylene homopolymer (A) [hereinafter sometimes referred to as "component (A)" or "homopolymer (A)"], which has an MFR (MFR2) measured at a temperature of 190°C and a load of 2.16 kg in the range of 100 to 600 g / 10 min, preferably 200 to 500 g / 10 min, and is preferably polymerized with a Ziegler-Natta catalyst.

[0024] Component (A) of the present invention may contain at least one constituent unit derived from biomass-derived monomer (ethylene). The same type of ethylene constituting component (A) may consist solely of biomass-derived ethylene, or it may contain both biomass-derived ethylene and fossil fuel-derived ethylene. Biomass-derived ethylene is ethylene made from any renewable natural raw materials and their residues, including fungi, yeasts, algae, and bacteria, which are of plant or animal origin, and contains carbon 14 10 C isotopes -12 It contains a certain proportion, and the biomass carbon concentration (pMC), measured according to ASTM D 6866, is approximately 100 pMC. Biomass-derived ethylene can be obtained by conventionally known methods.

[0025] It is preferable from the viewpoint of reducing environmental impact that component (A) related to the present invention contains biomass-derived ethylene.

[0026] By ensuring that the MFR2 of component (A) in this invention satisfies the above range, the shear viscosity of the ethylene polymer composition containing component (A) does not become excessively high, reducing the resin pressure of the extruder and improving moldability. Furthermore, because the amount of low molecular weight components does not become excessive, short-term creep strength is improved.

[0027] The MFR2 of component (A) related to the present invention was measured in accordance with JIS K7210-1.

[0028] Component (A) according to the present invention preferably has an intrinsic viscosity [η] measured in a decalin solvent at 135°C in the range of 0.55 to 0.75 dl / g, more preferably in the range of 0.58 to 0.72 dl / g. When the intrinsic viscosity [η] is in the above range, the shear viscosity of the ethylene-based polymer composition containing component (A) does not become too high, the resin pressure of the extruder decreases, and the moldability becomes good. Also, since the amount of low molecular weight components does not become too large, the short-term creep strength becomes good.

[0029] Component (A) according to the present invention preferably has a density of 960 kg / m 3 or more, more preferably 965 kg / m 3 or more. More preferably, it is in the range of 963 to 973 kg / m 3 , and even more preferably in the range of 965 to 971 kg / m 3 . When the density of component (A) is in such a range, it becomes easy to make the density of the ethylene-based polymer composition containing component (A) within a range that satisfies the following requirement (i).

[0030] Component (A) according to the present invention also preferably has a molecular weight distribution (Mw / Mn) measured by GPC in the range of 3.0 to 7.0, more preferably in the range of 4.0 to 6.0. The molecular weight distribution (Mw / Mn) of component (A) can be determined by the method based on the GPC peak separation of the ethylene-based polymer composition described later. Alternatively, it can be determined by collecting component (A) in the production process of the ethylene-based polymer composition and performing GPC measurement.

[0031] <Ethylene·α-olefin copolymer (B)> The ethylene·α-olefin copolymer (B) [hereinafter, may be referred to as "component (B)" in some cases], which is one of the components constituting the ethylene-based polymer composition of the present invention, is a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, preferably having an intrinsic viscosity [η] measured in a decalin solvent at 135°C in the range of 7.0 to 14 dl / g, more preferably in the range of 8.0 to 12 dl / g. The α-olefin having 4 or more carbon atoms preferably has 20 or less carbon atoms. The density of component (B) is preferably 920 to 945 kg / m 3More preferably 925-940 kg / m 3 Particularly preferred is 930-935 kg / m 3 It is within this range. Furthermore, the molecular weight distribution (Mw / Mn) measured by GPC is preferably in the range of 4.0 to 8.0, more preferably 5.0 to 7.0. The molecular weight distribution (Mw / Mn) of component (B) can usually be determined by the GPC peak separation method of the ethylene-based polymer composition described later. Alternatively, if it is possible to collect only component (B) during the manufacturing process of the ethylene-based polymer composition, it can be determined by measuring component (B) using GPC.

[0032] When the intrinsic viscosity [η] of component (B) is within the above range, the creep strength of the ethylene-based polymer composition containing component (B) is good.

[0033] The α-olefin having 4 or more carbon atoms constituting component (B) in the present invention may be a plurality of α-olefins, specifically including 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, and 1-decene. Among these α-olefins, 1-butene or 1-hexene is preferred, and 1-butene is more preferred. In terms of manufacturing cost, 1-butene is more preferred, but in terms of creep strength of the resulting ethylene-based polymer composition and molded article, 1-hexene is more preferred.

[0034] Component (B) of the present invention may contain at least one biomass-derived ethylene and / or biomass-derived α-olefin. The same type of ethylene and / or α-olefin constituting component (B) may consist only of biomass-derived ethylene and / or biomass-derived α-olefin, or it may contain both biomass-derived ethylene and / or biomass-derived α-olefin and fossil fuel-derived α-olefin and / or fossil fuel-derived ethylene. Biomass-derived ethylene and / or biomass-derived α-olefin are ethylene and / or α-olefins made from any renewable natural raw materials and their residues, including fungi, yeasts, algae, and bacteria, derived from plants or animals, and containing 10¹⁴C isotopes as carbon. -12 It contains a certain proportion, and the biomass carbon concentration (pMC) measured according to ASTM D 6866 is approximately 100 pMC. Biomass-derived ethylene and biomass-derived α-olefins can be obtained by conventionally known methods.

[0035] It is preferable from the viewpoint of reducing environmental impact that component (B) related to the present invention contains biomass-derived ethylene and / or α-olefins.

[0036] Component (B) in this invention preferably has a density of 910 to 960 kg / m³. 3 , more preferably 922-948 kg / m 3 It is within this range. When the density of component (B) is within this range, it becomes easy to bring the density of the ethylene polymer composition containing component (B) to a range that satisfies the following requirement (i).

[0037] The method of producing component (B) according to the present invention is not particularly limited as long as it has the above-mentioned properties, but polymers polymerized using a multi-site catalyst are preferred because they have a broad molecular weight distribution and improve moldability.

[0038] Here, a multi-site catalyst is a conventionally known catalyst having a large number of active sites, such as the Ziegler-Natta catalyst (hereinafter sometimes referred to as the "Ziegler catalyst"), a chromium-based catalyst (Phillips catalyst), or a standard catalyst. Among these catalysts, the Ziegler catalyst is preferred.

[0039] Ethylene-based polymer compositions The present invention provides an ethylene-based polymer composition (hereinafter sometimes referred to as "polymer composition") comprising 40 to 60% by mass of component (A), preferably 45 to 58% by mass, more preferably 50 to 56% by mass, and 60 to 40% by mass of component (B), preferably 55 to 42% by mass, more preferably 50 to 44% by mass [provided that the total amount of (A) + (B) is 100% by mass], characterized in that it satisfies the following requirements (i) to (iii).

[0040] <Requirement (i)> Density of 940-960 kg / m³ 3 Preferably 945-958 kg / m 3 , more preferably 948-956 kg / m 3 It is within the range.

[0041] By satisfying the above range, the polymer composition exhibits good long-term creep strength.

[0042] <Requirement (ii)> The amount of components with logM ≥ 7, as measured by GPC, is in the range of 0.35 to 0.80%, preferably 0.38 to 0.75%, and more preferably 0.40 to 0.70%.

[0043] A polymer composition that satisfies requirement (ii) can be obtained by adjusting the amounts of component (A) and component (B) contained in the polymer composition to be within the above range. Furthermore, the amount of component with logM≧7 can be controlled to be larger by adjusting in the direction of increasing the magnitude of the intrinsic viscosity [η] of component (B). In addition, in ethylene-based polymer compositions, the amount of component with logM≧7 tends to increase as the value of Mz, which will be described later, increases.

[0044] When the polymer composition satisfies the above range, the shear viscosity does not become too high, and the long-term creep strength is good. If the amount of components with logM≧7 is too high, the shear viscosity of the polymer composition will become too high, which may increase the resin pressure in the extruder and worsen moldability. Also, the appearance when made into pipes may deteriorate. If the amount of components with logM≧7 is too low, the long-term creep strength of the polymer composition may decrease.

[0045] <Requirement (iii)> The amount of components with logM ≤ 3, as measured by GPC, is 1.85% or less, preferably 1.75% or less.

[0046] A polymer composition that satisfies requirement (iii) can be obtained by setting the amounts of component (A) and component (B) contained in the polymer composition within the above range. The amount of component with logM ≤ 3 is influenced by the type and concentration of catalyst and electron donor used during production, and other polymerization conditions, but it can usually be adjusted in the direction of decreasing the amount of component with logM ≤ 3 by adjusting the intrinsic viscosity [η] of component (A) to be larger. In addition to the intrinsic viscosity [η] of component (A), the content of component (A) also affects the amount of component with logM ≤ 3, and usually, reducing the content of component (A) results in a smaller amount of component with logM ≤ 3. Furthermore, regarding the hexane used as the polymerization solvent, by increasing the proportion of hexane solvent obtained by centrifugation of the polymer slurry containing the mother liquor after the reaction in the second polymerization tank (recycled hexane) that is returned to the polymerization tank, more low molecular weight components contained in the recycled hexane are incorporated into the polymer, and the amount of component with logM ≤ 3 increases. In other words, by decreasing the proportion of recycled hexane returned to the polymerization tank, it is possible to adjust in the direction of decreasing the amount of component with logM ≤ 3.

[0047] There is no specific lower limit for the amount of components in a polymer composition where logM ≤ 3, but it is usually 0.50% or more, or 1.00% or more.

[0048] By keeping the amount of components with logM ≤ 3 in the polymer composition below 1.85%, the long-term creep strength is improved.

[0049] In addition to the above requirements (i) to (iii), the ethylene-based polymer composition of the present invention has a molecular weight distribution (Mw / Mn) measured by GPC preferably in the range of 30 to 70, more preferably 40 to 65, even more preferably 45 to 65, and particularly preferably 50 to 65.

[0050] If the Mw / Mn ratio of the polymer composition of the present invention is too low, the shear viscosity of the polymer composition may become too high, which may increase the resin pressure of the extruder and worsen the moldability. Conversely, if the Mw / Mn ratio is too high, poor mixing of component (A) and component (B) may occur, which may worsen the appearance during pipe molding.

[0051] The GPC-measured chart of the polymer composition of the present invention typically shows a bimodal molecular weight distribution.

[0052] In addition to the above requirements (i) to (iii), the ethylene-based polymer composition of the present invention preferably has a Z-average molecular weight (Mz) of 2.0 × 10 as measured by GPC. 6 The above is more 3.0 × 10 6 More preferably 4.0 × 10 6 That's all. The upper limit is usually 5.5 × 10 6 Below, or 5.0 × 10 6 The following applies:

[0053] Furthermore, in the ethylene polymer composition of the present invention, the ratio of Mw / Mn of component (A) to Mw / Mn of component (B), (Mw / Mn(B)) / (Mw / Mn(A)), is preferably greater than 0.9, more preferably 1.0 or greater, and even more preferably 1.1 or greater.

[0054] The polymer composition of the present invention preferably has an MFR (MFR5) in the range of 0.03 to 0.3 g / 10 min, more preferably 0.05 to 0.25 g / 10 min, measured at a temperature of 190°C and a load of 5 kg.

[0055] When the MFR5 of the copolymer composition satisfies the above range, the creep strength is improved while maintaining moldability and low sagging properties.

[0056] Furthermore, the ethylene polymer composition of the present invention is subjected to MFR (hereinafter referred to as MFR) at 190°C and a load of 21.6 kg. 21.6 ) and the ratio of MFR5 (MFR 21.6 MFR5) is 40 or higher, preferably 50 or higher. 21.6 The ratio of MFR5 (MFR 21.6 MFR (Medium-Resistant Fiber Rate) is usually below 100. 21.6 By using an ethylene-based polymer composition in which / MFR5 is within the above range, polyethylene pipes with excellent moldability, fracture stress resistance, and hot internal pressure creep characteristics can be obtained.

[0057] The MFR (MFR5 and MFR) of the polymer composition according to the present invention 21.6 The measurements were performed in accordance with JIS K7210-1.

[0058] 《Ethylene-based polymer composition 2》 The ethylene polymer composition of the present invention can also be defined as follows (hereinafter referred to as "ethylene polymer composition 2").

[0059] The ethylene-based polymer composition 2 of the present invention consists of an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, and is an ethylene-based polymer composition that satisfies the following requirements (i) to (vi). (i) Density of 940-960 kg / m³ 3 It is within the range. (ii) The amount of components with logM ≥ 7 measured by GPC is in the range of 0.35 to 0.80%. (iii) The amount of components with logM ≤ 3 measured by GPC is 1.85% or less. (iv) The MFR (MFR5) measured at a temperature of 190°C and a load of 5 kg is in the range of 0.03 to 0.3 g / 10 min. (v) The molecular weight distribution (Mw / Mn) measured by GPC is in the range of 30 to 70. (vi) The resulting pipe satisfies the following conditions (a) to (d) simultaneously in a hot internal pressure creep test measured in accordance with ISO 1167. (a) The fracture time at a test temperature of 20°C and a test circumferential stress of 12.7 MPa is 500 hours or more. (b) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.3 MPa is 100 hours or more. (c) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.1 MPa is 1,000 hours or more. (d) The fracture time at a test temperature of 80°C and a test circumferential stress of 5.7 MPa is 3,000 hours or more.

[0060] Requirements (i) to (v) above have already been described in detail in this specification, and requirement (vi) will be described later in the section on pipes.

[0061] The ethylene-based polymer composition 2 is preferably further satisfied with the following requirement (vii). (vii) The chart measured by GPC shows bimodality, and the content ratio of low molecular weight components to high molecular weight components obtained by peak separation is in the range of 40:60 to 60:40. More preferably, it is in the range of 50:50 to 60:40, and even more preferably, in the range of 55:45 to 60:40.

[0062] Peak separation in GPC charts can be achieved by performing curve fitting on two normal distribution curves to separate the bimodal peaks appearing in the molecular weight distribution curve. Alternatively, it is possible to perform GPC measurements on the entire molecule, separate the peaks obtained from the multimodal molecular weight distribution curve using commercially available data analysis software, and calculate the component ratios. For example, based on a program created using Visual Basic in Microsoft Excel, the two peak curves to be separated are assumed to be log-normal distributions, and the molecular weight distribution curve is separated into two peak curves with different molecular weights through convergence calculation. The recombined curve of the two separated peak curves is compared with the GPC chart, and the calculation is performed while changing the initial values ​​so that the two curves are approximately identical. The calculation is performed by dividing Log(molecular weight) [LogM] into 0.02 intervals and normalizing the intensity so that the area of ​​the measured molecular weight curve and the area of ​​the recombined curve of the two separated peak curves are equal.

[0063] The low molecular weight component corresponds to component (A) of the aforementioned ethylene-based polymer composition, and the high molecular weight component corresponds to component (B) of the aforementioned ethylene-based polymer composition.

[0064] To achieve the physical properties described in requirement (vi) above, it is desirable that the low molecular weight component consists of an ethylene homopolymer. This can be achieved by producing an ethylene homopolymer (A) according to the manufacturing method described later. In this case, the high molecular weight component consists of a copolymer of ethylene and an α-olefin having 4 or more carbon atoms.

[0065] Other requirements that ethylene-based polymer composition 2 preferably satisfies are as previously described for ethylene-based polymer compositions.

[0066] Pigments, additives The ethylene-based polymer composition of the present invention preferably contains 0.01 to 3 parts by mass, and more preferably 0.05 to 2 parts by mass, of one or more pigments selected from titanium dioxide, titanium yellow, phthalocyanine blue, isoindolinone, quinacridone compounds, condensed azo compounds, ultramarine, and cobalt blue, per 100 parts by mass of the polymer composition (total amount of (A) + (B)). By adding such pigments, a pipe suitable for water pipes or gas pipes can be obtained. The color of the pipe may be, for example, blue, yellow, orange, white, red, green, or purple.

[0067] Furthermore, it is preferable that the ethylene-based polymer composition of the present invention contains 0.01 to 3 parts by mass, preferably 0.5 to 2.5 parts by mass, and more preferably 2.0 to 2.5 parts by mass, of carbon black per 100 parts by mass of the polymer composition (total amount of (A) + (B)). By adding carbon black, a pipe suitable for water pipes or gas pipes with excellent weather resistance can be obtained. In this case, the color of the pipe is black, gray, etc.

[0068] Furthermore, the ethylene-based polymer composition of the present invention can be used in various molded article applications described later after adding other resins to the polymer composition. Examples of other resins include ethylene-based resins such as high-density polyethylene, low-density polyethylene, very low-density polyethylene, and ultra-low-density polyethylene, as well as polyolefin rubber. The amount added is, for example, 10 parts by mass or less per 100 parts by mass of the polymer composition (total amount of (A) + (B)).

[0069] The ethylene-based polymer composition of the present invention may optionally contain additives commonly used in olefin polymers, such as weather-resistant stabilizers, heat-resistant stabilizers, antistatic agents, anti-slip agents, anti-blocking agents, anti-fogging agents, lubricants, dyes, nucleating agents, plasticizers, anti-aging agents, hydrochloric acid absorbers, and antioxidants, to the extent that the objectives of the present invention are not impaired.

[0070] Method for producing ethylene-based polymer compositions The polymer composition of the present invention preferably consists of the ethylene homopolymer (A) and the ethylene-α-olefin copolymer (B) that constitute the ethylene polymer composition, which are preferably produced by slurry polymerization using a MgCl2-based Ziegler-Natta catalyst. Components (A) and (B) may be polymerized individually or in a multi-stage polymerization. When each is polymerized individually, the ethylene polymer composition can be obtained by mixing or melt-kneading each component (A, B) by a conventionally known method. For example, the ethylene polymer composition can be obtained by melting and kneading each component (A, B) using an extruder, Brabender plastograph, Bambari mixer, kneader blender, etc. In the case of multi-stage polymerization, the dispersibility of each component (A, B) is good, and the appearance of the pipes formed from the ethylene polymer composition according to the present invention is good.

[0071] Molded bodies, pipes The ethylene polymer composition of the present invention can be used in various existing applications of ethylene resins by molding it to obtain various molded articles. The ethylene polymer composition of the present invention is particularly suitable for pipe applications. The ethylene polymer composition of the present invention has excellent pipe moldability, and by molding it, pipes with excellent long-term durability and multilayer pipes can be obtained. Here, this multilayer pipe is formed from a layer in which at least one layer is made of the copolymer composition of the present invention. In this multilayer pipe molded article, the layer made of the copolymer composition may be formed on only one side, or on both sides, and the pigment of the "other blending components" may be blended on one of the two sides. The substrate constituting this multilayer pipe may be made of the copolymer composition, or it may be made of a material other than the copolymer composition.

[0072] Other resins used when the pipe is multilayered are not particularly limited and include, for example, crystalline resins, rubbers, adhesive resins, and barrier resins. Specifically, these include high-density polyethylene, low-density polyethylene, very low-density polyethylene, ultra-low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer saponified product, ethylene-styrene copolymer, ethylene-vinylcyclohexane copolymer, ethylene-norbornene copolymer, polyolefin rubber, styrene-butadiene rubber, styrene-butadiene-styrene block copolymer, isoprene rubber, styrene-isoprene rubber, isobutylene rubber, etc., as well as acid-modified and hydrogenated versions of these resins.

[0073] The pipes of the present invention are formed using a known pipe molding method from the copolymer composition of the present invention. For example, the copolymer composition is melted using an extruder of a pipe manufacturing apparatus at a temperature of 150°C to 220°C, preferably 160°C to 210°C, then extruded from a die into a cylindrical shape, and finally cooled with water.

[0074] The shape of the pipe of the present invention can be appropriately determined depending on the application of the pipe. For example, it includes polyethylene pipes molded to the outer diameter and wall thickness described in ISO 4427, ISO 4437, JIS K6761, JIS K6762, or JIS K6774. Furthermore, these molded articles include molded articles (such as laminates) that include a portion made of an ethylene-based polymer composition and a portion made of another resin.

[0075] The pipe of the present invention is characterized by simultaneously satisfying the following (a) to (d) in a hot internal pressure creep test measured in accordance with ISO 1167. (a) The fracture time at a test temperature of 20°C and a test circumferential stress of 12.7 MPa is 500 hours or more. (b) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.3 MPa is 100 hours or more. (c) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.1 MPa is 1,000 hours or more. (d) The fracture time at a test temperature of 80°C and a test circumferential stress of 5.7 MPa is 3,000 hours or more. [Examples]

[0076] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0077] The methods for measuring the properties and physical characteristics of each component used in the examples are as follows.

[0078] (1) 2.16 kg load melt flow rate (MFR2, g / 10 min) Measurements were taken in accordance with JIS K7210-1, under conditions of 190°C and a 2.16 kg load.

[0079] (2) 5kg load melt flow rate (MFR 5, g / 10 min) Measurements were taken in accordance with JIS K7210-1, under conditions of 190°C and a 5kg load.

[0080] (3) 21.6 kg load melt flow rate (MFR) 21.6 ,g / 10min) Measurements were taken in accordance with JIS K7210-1, under conditions of 190°C and a 21.6 kg load.

[0081] (4) Density (kg / m 3 ) Density was measured according to JIS K7112. The strands obtained during MFR measurement were heat-treated at 100°C for 1 hour, then left at room temperature for 1 hour, and finally measured using the density gradient tube method.

[0082] Density of ethylene-α-olefin copolymer (B) in multi-stage polymerization (D B ) is the mass fraction BR of ethylene homopolymer (A) A , density D A and density D of the ethylene polymer composition C This was obtained using the following equation (Eq-1).

[0083] BR B / D B =(1 / D C )-(BR A / D A ) -------- (Eq-1) (5) Intrinsic viscosity ([η], dl / g) The intrinsic viscosity was determined by dissolving approximately 20 mg of the sample in 15 ml of decalin and measuring the specific viscosity ηsp in an oil bath at 135°C. After diluting this decalin solution by adding 5 ml of decalin solvent, the specific viscosity ηsp was measured again in the same manner. This dilution procedure was repeated two more times, and the intrinsic viscosity [η] (unit: dl / g) was determined by extrapolating the concentration (C) to 0 as shown in the following equation (Eq-2) using the value of ηsp / C.

[0084] [η]=lim(ηsp / C) (C→0)--------- (Eq-2) Furthermore, the intrinsic viscosity ([η]) of the ethylene-α-olefin copolymer (B) in multi-stage polymerization. B ) is the mass fraction BR of ethylene homopolymer A , intrinsic viscosity [η] A and the intrinsic viscosity [η] of the ethylene polymer compositionC This was obtained using the following formula (Eq-3).

[0085] [η] B =([η] C -[η] A ×BR A )) / (1-BR A ) -------- (Eq-3) (6)logM≧7 component amount, logM≦3 component amount The amount of logM≧7 components was measured using a Tosoh HLC-8321 GPC / HT type gel permeation chromatograph as follows.

[0086] Analysis software: Chromatography data system Empower3 (Waters, registered trademark), Column: TSKgel GMH6-HT x 2 + TSKgel GMH6-HTL x 2 (inner diameter 7.5 mm x length 30 cm, manufactured by Tosoh Corporation), Mobile phase: o-Dichlorobenzene (Wako Pure Chemical Industries, special grade reagent), Detector: Differential refractometer (built into the device), Column temperature: 140°C, Flow rate: 1.0 mL / min, Injection volume: 400 μL, Sampling time interval: 0.5 seconds, Sample concentration: 0.1% (w / v), Molecular weight calibration: Monodisperse polystyrene (manufactured by Tosoh Corporation); #3std set.

[0087] A molecular weight distribution curve was created based on the standard polyethylene molecular weight, following the general calibration procedure described in Z. Crubisic, P. Rempp, H. Benoit, J. Polym. Sci., B5, 753 (1967).

[0088] The amount of components with logM ≥ 7 was calculated using the molecular weight distribution curve (G1) of the obtained ethylene-based polymer composition by the following method. In this specification, when "molecular weight distribution curve" is used, it refers to the differential molecular weight distribution curve unless otherwise specified, and when "area" is used with respect to the molecular weight distribution curve, it refers to the area of ​​the region formed between the molecular weight distribution curve and the baseline.

[0089] For each numerical data in (G1), Log(molecular weight, hereafter M) is divided into 0.02 intervals, and further, for each of (G1), the intensity [dwt / d(logM)] is normalized so that the area is 1.

[0090] Subsequently, the sum of normalized dwt / dlogM for logM≧7 was calculated and used as the component quantity for logM≧7. Similarly, the sum of normalized dwt / dlogM for logM≦3 was calculated and used as the component quantity for logM≦3.

[0091] (7) Molecular weight distribution (Mw / Mn), average molecular weight (Mw,Mn,Mz) Using the method described in (6) above, Mw / Mn was calculated from the weight-average molecular weight (Mw), number-average molecular weight (Mn), and z-average molecular weight (Mz) calculated as equivalent to the molecular weight of standard polyethylene.

[0092] (7-2) Peak separation of molecular weight distribution The bimodal peaks appearing in the molecular weight distribution curve were curve-fitted with two normal distribution curves to separate the peaks, and the content ratio of each component, as well as the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of each component were determined.

[0093] (8) Hot internal pressure creep test: failure time <Method for forming pipes> An ethylene polymer composition (C) was extruded using a 65 mmφ, L / D=25 pipe forming machine manufactured by Ikegai Iron Works Co., Ltd. at a set temperature of 200°C and an extrusion rate of 22 kg / hr to obtain a polyethylene pipe with an SDR of 11 and a diameter of 60 mm.

[0094] <Internal pressure creep failure time> The pipe length was 50 cm, and the temperature was 20°C or 80°C. At 20°C, the circumferential stress was measured in the range of 11-15 MPa, and at 80°C, the circumferential stress was measured in the range of 5-7 MPa, according to ISO 1167.

[0095] (9) Tensile fatigue strength at 80°C (FNFT fracture stress: MPa) The obtained polyethylene pipe was cut into a rectangular prism measuring 6 mm in length, 6 mm in width, and 60 mm in length to serve as the evaluation sample. Tensile fatigue strength (specimen shape) was tested in accordance with JIS K6774. The general test conditions for a full-circumference notch type with a notch depth of 1 mm are shown below.

[0096] The specimen shape (6mm x 6mm x 60mm rectangular prism with notch), test waveform and test frequency (square wave, 0.5Hz), test temperature 80°C, and actual stress were measured at several points in the range of 10 to 18 MPa. The fatigue strength was defined as the number of fatigue cycles at which the specimen fractured. Measurements were taken at least three points with different actual stresses, and measurements were taken in a range of three orders of magnitude or more in the number of fracture cycles or an actual stress of 3 MPa or more. An approximation formula was created using the least squares method with power approximation to determine the actual stress corresponding to 10,000 and 100,000 fracture cycles.

[0097] [Example 1] <Production of ethylene homopolymer (A-1)> A Ziegler-Natta catalyst based on MgCl2 was used.

[0098] Internal volume 0.34m 3 In the first polymerization tank, n-hexane was continuously supplied at a rate of 70.7 L / hr, catalyst at 1.9 mmol-Ti / hr, and triethylaluminum at 11 mmol-Al / hr. The contents of the polymerization tank were continuously withdrawn to maintain a constant liquid level. Ethylene homopolymer (A) was polymerized under the conditions of a polymerization temperature of 85°C, a reaction pressure of 0.65 MPaG, and an average residence time of 2.0 hr. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.4 mol / mol) The contents continuously withdrawn from the first polymerization tank are substantially removed of unreacted ethylene and hydrogen in a flash drum maintained at an internal pressure of 0.03 MPa and a temperature of 30°C.

[0099] The physical properties of the homopolymer (A-1), from which unreacted ethylene and hydrogen had been substantially removed, were measured by the method described above.

[0100] <Production of copolymer (B-1) and copolymer composition (C-1)> Subsequently, the contents had a volume of 0.2 m³. 3 The mixture was continuously supplied to the second polymerization tank, and ethylene-1-butene copolymer (B-1) was polymerized under the conditions of n-hexane 57 L / hr, polymerization temperature 72°C, reaction pressure 0.30 MPaG, and average residence time 1.0 hr. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.031 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.016 mol / mol. In the second polymerization tank, the contents of the polymerization tank were continuously withdrawn to maintain a constant liquid level, and n-hexane and unreacted monomers in the contents were removed using a solvent separation device and dried to obtain an ethylene-based polymer composition (C-1) containing the homopolymer (A-1) and ethylene-1-butene copolymer (B-1). The yield of the obtained copolymer composition (C-1) was 16 kg / hr.

[0101] The amount and physical properties of copolymer (B-1) contained in composition (C-1), as well as the physical properties of composition (C-1), were measured by the method described above.

[0102] Next, 0.15 parts by mass of calcium stearate as a hydrochloric acid absorbent, 0.2 parts by mass of BASF Irganox 1010 and 0.1 parts by mass of BASF Irgafos 168 as antioxidants, and 0.1 parts by mass of BASF Tinuvin 622LD as a weather stabilizer were added to 100 parts by mass of the copolymer composition. Then, using a GM40-28 extruder manufactured by GM Sansei Co., Ltd., the mixture was melt-kneaded at a set temperature of 200°C and a screw rotation speed of 80 rpm, extruded into strands, and cut to obtain pellets.

[0103] Table 1 shows the physical properties of the resulting ethylene-based polymer composition pellets. Table 2 shows the results of evaluating the performance of pipes formed using the method described above.

[0104] [Example 2] Internal volume 0.34m 3In the first polymerization tank, n-hexane was continuously supplied at 71.8 L / hr, the same catalyst as in Example 1 at 1.9 mmol-Ti / hr, and triethylaluminum at 14 mmol-Al / hr. The ethylene homopolymer (A-2) was polymerized under the same polymerization temperature, reaction pressure, and average residence time of 1.9 hr as in Example 1, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.3 mol / mol) (A-2), which was removed from the first polymerization tank, has an internal volume of 0.2 m³. 3 The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer (B-2) was polymerized under the same conditions as in Example 1. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.031 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.017 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 17 kg / hr.

[0105] Furthermore, the amount and physical properties of (B-2) contained in composition (C-2), as well as the physical properties of composition (C-2) and the results of performance evaluation after pipe molding are shown in Tables 1 and 2, using the same method as in Example 1.

[0106] [Example 3] Internal volume 0.34m 3 In the first polymerization tank, n-hexane was continuously supplied at a rate of 70.4 L / hr, the same catalyst as in Example 1 at a rate of 1.9 mmol-Ti / hr, and triethylaluminum at a rate of 11 mmol-Al / hr. The ethylene homopolymer (A-3) was polymerized under the same polymerization temperature, reaction pressure, and average residence time of 1.9 hr as in Example 1, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.2 mol / mol) (A-3), which was removed from the first polymerization tank, has an internal volume of 0.2 m³. 3 The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer (B-3) was polymerized under the same conditions as in Example 1. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.018 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.007 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 17 kg / hr.

[0107] Furthermore, the results of performance evaluation after measuring physical properties and forming pipes using the same method as in Example 1 are shown in Tables 1 and 2.

[0108] [Comparative Example 1] Internal volume 0.34m 3 In the first polymerization tank, 70.3 L / hr of n-hexane, 1.9 mmol-Ti / hr of the same catalyst as in Example 1, and 11 mmol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same polymerization temperature, reaction pressure, and average residence time of 1.9 hr as in Example 1, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.2 mol / mol) The contents removed from the first polymerization tank had a volume of 0.2 m³. 3 The ethylene-1-butene copolymer was continuously supplied to the second polymerization tank and polymerized under the same conditions as in Example 1. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.043 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.007 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 20 kg / hr.

[0109] Furthermore, the results of performance evaluation after measuring physical properties and forming pipes using the same method as in Example 1 are shown in Tables 1 and 2.

[0110] [Comparative Example 2] Internal volume 0.34m 3 In the first polymerization tank, 73.6 L / hr of n-hexane, 1.9 mmol-Ti / hr of the same catalyst as in Example 1, and 15 mmol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same conditions as in Example 1, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.5 mol / mol) The contents removed from the first polymerization tank had a volume of 0.2 m³. 3 The ethylene-1-butene copolymer was continuously supplied to the second polymerization tank and polymerized under the same conditions as in Example 1. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.050 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.025 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 17 kg / hr.

[0111] Furthermore, the results of performance evaluation after measuring physical properties and forming pipes using the same method as in Example 1 are shown in Tables 1 and 2.

[0112] [Comparative Example 3] Internal volume 0.34m 3In the first polymerization tank, 68 L / hr of n-hexane, 3.8 mmol-Ti / hr of the same catalyst as in Example 1, and 50 mmol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized at a polymerization temperature of 85°C, a reaction pressure of 0.6 MPaG, and an average residence time of 2.0 hr, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.1 mol / mol) The contents removed from the first polymerization tank had a volume of 0.2 m³. 3 The ethylene-1-butene copolymer was polymerized under the following conditions: polymerization temperature 72°C, reaction pressure 0.3 MPaG, and average residence time 1.0 hr. Ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.077 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.020 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 19 kg / hr.

[0113] Furthermore, the results of performance evaluation after measuring physical properties and forming pipes using the same method as in Example 1 are shown in Tables 1 and 2.

[0114] [Comparative Example 4] Internal volume 0.34m 3 In the first polymerization tank, 68 L / hr of n-hexane, 3.2 mmol-Ti / hr of the same catalyst as in Example 1, and 50 mmol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same conditions as in Comparative Example 3, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 4.8 mol / mol) The contents removed from the first polymerization tank had a volume of 0.2 m³. 3The polymer was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer was polymerized under the same polymerization temperature, reaction pressure, and average residence time of 1.1 hr as in Comparative Example 3. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.077 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.011 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 17 kg / hr.

[0115] Furthermore, the results of performance evaluation after measuring physical properties and forming pipes using the same method as in Example 1 are shown in Tables 1 and 2.

[0116] [Comparative Example 5] Internal volume 0.34m 3 In the first polymerization tank, 68 L / hr of n-hexane, 3.1 mmol-Ti / hr of the same catalyst as in Example 1, and 50 mmol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same conditions as in Comparative Example 3, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.4 mol / mol) The contents removed from the first polymerization tank had a volume of 0.2 m³. 3 The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer was polymerized under the same conditions as in Comparative Example 3. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.062 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.017 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 19 kg / hr.

[0117] Furthermore, the results of performance evaluation after measuring physical properties and forming pipes using the same method as in Example 1 are shown in Tables 1 and 2.

[0118] [Example 4] Internal volume 60m 3 In the first polymerization tank, 14850 L / hr of n-hexane, 1.1 mol-Ti / hr of the same catalyst as in Example 1, and 7.4 mol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same conditions as in Comparative Example 3, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.9 mol / mol) The contents removed from the first polymerization tank had a volume of 60 m³. 3 The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer was polymerized under the same conditions as in Comparative Example 3. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.018 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.021 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 11,000 kg / hr.

[0119] [Example 5] Internal volume 60m 3 In the first polymerization tank, 14850 L / hr of n-hexane, 1.1 mol-Ti / hr of the same catalyst as in Example 1, and 7.4 mol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same conditions as in Comparative Example 3, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.9 mol / mol) The contents removed from the first polymerization tank had a volume of 60 m³. 3The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer was polymerized under the same conditions as in Comparative Example 3. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.010 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.016 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 11,000 kg / hr.

[0120] [Reference example 1] Internal volume 60m 3 In the first polymerization tank, n-hexane was continuously supplied at a rate of 200 L / hr, the same catalyst as in Example 1 at a rate of 1.6 mol-Ti / hr, and triethylaluminum at a rate of 10 mol-Al / hr. The ethylene homopolymer was polymerized at a polymerization temperature of 87°C, a reaction pressure of 0.6 MPaG, and an average residence time of 2.0 hr, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 6.4 mol / mol) The contents removed from the first polymerization tank had a volume of 60 m³. 3 The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer was polymerized under conditions of polymerization temperature of 84°C, reaction pressure of 0.3 MPaG, and average residence time of 1.0 hr. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.02 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.047 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 16,000 kg / hr.

[0121] [Reference example 2] Internal volume 60m 3In the first polymerization tank, 19600 L / hr of n-hexane, 1.3 mol-Ti / hr of the same catalyst as in Example 1, and 9.8 mol-Al / hr of triethylaluminum were continuously supplied. The ethylene homopolymer was polymerized under the same conditions as in Comparative Example 3, while continuously withdrawing the contents of the polymerization tank to maintain a constant liquid level. Ethylene, hydrogen, and nitrogen were continuously supplied during polymerization to maintain a constant gas composition. (Gas composition (molar ratio): hydrogen / ethylene = 5.2 mol / mol) The contents removed from the first polymerization tank had a volume of 60 m³. 3 The material was continuously supplied to the second polymerization tank, and the ethylene-1-butene copolymer was polymerized under the same conditions as in Comparative Example 3. During polymerization, ethylene, 1-butene, hydrogen, and nitrogen were continuously supplied to maintain a constant gas composition. The supply ratio of 1-butene to ethylene was 0.069 kg / kg, and the gas composition (molar ratio) of hydrogen and ethylene was hydrogen / ethylene = 0.057 mol / mol. The obtained contents were separated from the solvent and unreacted monomers in the same manner as in Example 1, and dried to obtain an ethylene-based polymer composition. The yield was 13,200 kg / hr. [Comparison of Examples and Comparative Examples] Compared to Comparative Examples 3-5, which do not satisfy requirement (ii) due to the amount of components with logM≧7, Examples 1-3 all show significantly superior internal pressure creep rupture times at 80°C and σ=5.7MPa.

[0122] Compared to Comparative Examples 1 and 2, in which the amount of components with logM ≥ 7 satisfies requirement (ii), but the amount of components with logM ≤ 3 does not satisfy requirement (iii), Examples 1 to 3 all show significantly superior internal pressure creep rupture times at 20°C, σ = 12.7 MPa, 80°C, σ = 6.3 MPa, and 80°C, σ = 6.1 MPa.

[0123] In other words, the pipes obtained in Examples 1-3 exhibit excellent internal pressure creep failure time under a wide range of temperature and pressure conditions.

[0124] [Table 1]

[0125] [Table 2] [Industrial applicability]

[0126] The ethylene-based polymer composition of the present invention, which exhibits excellent moldability and mechanical strength, is suitably used for pipe applications such as water pipes and gas pipes.

Claims

1. MFR measured at temperature: 190°C, load: 2.16 kg (MFR 2 An ethylene-based polymer composition comprising 40 to 60% by mass of an ethylene homopolymer (A) having a carbon dioxide content in the range of 100 to 600 g / 10 min, and 60 to 40% by mass of a copolymer (B) of ethylene and an α-olefin having 4 or more carbon atoms [provided that the total amount of (A) + (B) is 100% by mass], characterized in that it satisfies the following requirements (i) to (iii). (i) Density of 940-960 kg / m³ 3 It is within the range. (ii) The amount of components with logM ≥ 7 measured by GPC is in the range of 0.35 to 0.80%. (iii) The amount of components with logM ≤ 3, as measured by GPC, is 1.85% or less.

2. The ethylene-based polymer composition according to claim 1, characterized in that the α-olefin having 4 or more carbon atoms is 1-butene or 1-hexene.

3. The ethylene-α-olefin copolymer (B) is characterized in that the intrinsic viscosity [η] is in the range of 7.0 to 14.0 dl / g, as described in claim 1.

4. The ethylene polymer composition measured at a temperature of 190°C and a load of 5 kg (MFR). 5 The ethylene-based polymer composition according to claim 1, characterized in that the amount is in the range of 0.03 to 0.3 g / 10 min.

5. The ethylene polymer composition according to claim 1, wherein the ethylene polymer composition has a molecular weight distribution (Mw / Mn) measured by GPC in the range of 30 to 70.

6. The ethylene-based polymer composition according to claim 1, wherein an ethylene homopolymer (A) and an ethylene-α-olefin copolymer (B) are polymerized using a Ziegler-Natta catalyst.

7. A pipe comprising the ethylene polymer composition according to any one of claims 1 to 6.

8. The pipe according to claim 7, characterized in that the pipe simultaneously satisfies (a) to (d) below in a hot internal pressure creep test measured in accordance with ISO 1167. (a) The fracture time at a test temperature of 20°C and a test circumferential stress of 12.7 MPa is 500 hours or more. (b) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.3 MPa is 100 hours or more. (c) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.1 MPa is 1,000 hours or more. (d) The fracture time at a test temperature of 80°C and a test circumferential stress of 5.7 MPa is 3,000 hours or more.

9. The pipe according to claim 7, characterized in that, per 100 parts by mass of the ethylene polymer composition, 0.01 to 3 parts by mass of one or more pigments selected from carbon black, titanium dioxide, titanium yellow, phthalocyanine blue, isoindolinone, quinacridone compounds, condensed azo compounds, ultramarine, and cobalt blue is added.

10. An ethylene-based polymer composition comprising an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 4 or more carbon atoms, satisfying the following requirements (i) to (vi). (i) Density of 940-960 kg / m³ 3 It is within the range. (ii) The amount of components with logM ≥ 7 measured by GPC is in the range of 0.35 to 0.80%. (iii) The amount of components with logM ≤ 3, as measured by GPC, is 1.85% or less. (iv) MFR measured at temperature: 190°C, load: 5 kg (MFR 5 The value is in the range of 0.03 to 0.3 g / 10 min. (v) The molecular weight distribution (Mw / Mn) measured by GPC is in the range of 30 to 70. (vi) The resulting pipe satisfies the following conditions (a) to (d) simultaneously in a hot internal pressure creep test measured in accordance with ISO 1167. (a) The fracture time at a test temperature of 20°C and a test circumferential stress of 12.7 MPa is 500 hours or more. (b) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.3 MPa is 100 hours or more. (c) The fracture time at a test temperature of 80°C and a test circumferential stress of 6.1 MPa is 1,000 hours or more. (d) The fracture time at a test temperature of 80°C and a test circumferential stress of 5.7 MPa is 3,000 hours or more.

11. Furthermore, the ethylene polymer composition according to claim 10 satisfies the following requirement (vii). (vii) The chart measured by GPC shows bimodality, and the content ratio of low molecular weight components to high molecular weight components, determined by peak separation, is in the range of 40:60 to 60:

40.

12. The ethylene-based polymer composition according to claim 11, wherein the low molecular weight component consists of an ethylene homopolymer, and the high molecular weight component consists of a copolymer of ethylene and an α-olefin having four or more carbon atoms.

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