JP2014227502A - Piping material, pipe, and joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piping material which is classified as PE 100 according to the ISO 9080 standard, requires a 100-year guarantee, is excellent in long-term properties under a high temperature acceleration condition, rigidity, elongation properties, impact resistance and moldability and furthermore is excellent in long-life reinforcement and surface properties of the SCG (slow crack growth), and to provide a pipe and a joint particularly.SOLUTION: The piping material contains a polyethylene resin composition which contains an ethylene homopolymer and/or a copolymer of ethylene and α-olefin having 3-20 carbon atoms and satisfies the following conditions (1)-(4). The condition (1) is that the density thereof is 948-952 kg/m. The condition (2) is that the melt flow rate (code T) thereof is equal to or higher than 0.15 g/10 minutes and lower than 0.30 g/10 minutes. The condition (3) is that the molecular weight distribution thereof is equal to or wider than 15 and narrower than 25. The condition (4) is that when a hot internal pressure creep test to be stipulated in ISO 9080 is applied thereto at 20°C and a plotted line of logarithms of rupture times versus those of hoop pressures is drawn, an inclination ratio of the plotted line satisfies the following relationship. (the inclination before 1,000 hours)/(that after 1,000 hours)>1.5.

Description

  The present invention relates to a piping material, a pipe, and a joint.

  Polyethylene resins have excellent creep characteristics, environmental stress crack resistance, impact characteristics, and flexibility, and have been widely used as piping materials. In this specification, “piping material” refers to pipes and joints used as water and sewage pipes, gas pipes, and water supply pipes. In recent years, it has been demonstrated that polyethylene pipes are superior to pipe types such as steel pipes and ductile cast iron pipes in that they have characteristics such as pipes extending and following ground changes even with earthquakes. Unlike mechanical joints such as steel pipes and ductile cast iron pipes, polyethylene joints can be welded to pipes with EF (electro-fusion) joints, so that construction is simple and excellent in earthquake resistance. Due to these characteristics, polyethylene resin has attracted attention as piping materials for water and sewage pipes, gas pipes, water supply pipes and the like.

  In addition, safety requirements for each piping material are high, and pipes made of materials that have acquired PE80 as a gas pipe and PE100 as a water supply pipe have come to be used. Here, “PE100” means that, in the hot internal pressure creep test described in ISO9080, a stress-fracture time curve at three different temperatures is measured up to at least 9,000 hours. Polyethylene classified as PE100 in the classification table stipulated in ISO12162, the value of 97.5% lower confidence limit (hereinafter referred to as LPL) of the estimated minimum guaranteed stress after 50 years Say. When polyethylene pipe resin is used as a water distribution pipe for a long time, stress is applied due to water pressure from the inside of the pipe or earth pressure from the outside during embedding. Disruption can occur. Improvements have been made to provide a material that does not cause brittle fracture cracking under such severe conditions of stress over a long period of time.

  In recent years, the number of pipes that have passed for a long time since the installation of water pipes and gas pipes has increased, and the proportion of so-called aging pipes that exceed the legal service life of 40 years has increased since laying, and leakage due to pipe breakage has become a problem. Yes. Since PE100 polyethylene pipe has a 50-year warranty, renewal is desired before 50 years, but the annual renewal rate is only 1%. Therefore, it is desired to develop a material that has a 100-year warranty, in which the service life guaranteed for the pipe is longer than the 50-year warranty of PE100.

  When an internal pressure is applied to a pipe at a constant temperature, a ductile fracture occurs in which a bulge occurs after a certain period of time and breaks. Between the fracture time of this ductile fracture and the stress due to the internal pressure, there is a stress-fracture time creep relationship in which the lower the stress, the longer the fracture time. This relationship is known to be lower stress and shorter time as the test temperature is higher, and higher stress and longer time as the density of the polyethylene resin is higher. Therefore, if the density of the polyethylene resin is increased, the stress on the long time side increases. However, when the density is increased, brittle fracture rapidly progresses. In the conventional polymerization design, for example, brittle fracture occurred before 100 years at 20 ° C., and in the stress-fracture time creep diagram, ductility Creep curve bending (Knee Point) occurs due to the transition from fracture to brittle fracture. For this reason, it has been difficult to achieve a material that has a lifetime of 100 years in the conventional resin design.

  Depending on the conventional resin design, even if the long-term characteristics are brittle, it is possible to obtain PE100 classified polyethylene pipe and joint resin. In particular, brittle fracture is noticeable under the internal pressure creep test conditions at 80 ° C. Even if such a material is classified into PE100 described in ISO, it can be said that PE100 is brittle at high temperatures. When trying to estimate long-term creep characteristics, brittle fracture progresses more rapidly than ductile fracture, making it difficult to predict fracture. Therefore, the brittle PE 100 whose life is difficult to predict is inappropriate as a material used for a lifeline such as a water pipe.

  Further, in order to obtain polyethylene classified as PE100, it is not so difficult as a resin design if only long-term characteristics and elongation characteristics are improved. However, it is very difficult for current technology to develop a material that maintains such physical properties and is excellent in moldability.

  Furthermore, since joints, which are one of the piping materials, are used by fusing with pipes, the joints themselves are subject to stress due to earth pressure in the ground and displacement of the pipes. Susceptible to stress concentration from deformation. Therefore, the joint needs to have better resistance against creep fracture.

  As described above, there is a demand for a material that satisfies the conflicting requirements, which is excellent in mechanical properties and brittle fracture resistance over a long period of time, excellent in moldability, and excellent in surface properties. As described above, a polyethylene resin composition classified as PE100 in the classification table defined in ISO12162 by measurement based on ISO9080, which has excellent moldability and is guaranteed for 100 years, is a lifeline. It is a material that is expected to be used for sewerage pipes, gas pipes, water supply pipes, etc. in the future.

  On the other hand, conventionally, in order to improve the mechanical properties of polyethylene over a long period of time, widening the molecular weight distribution and introducing a copolymerizable comonomer as a side chain during polymerization (for example, Patent Document 1, 2).

  In addition, in order to improve long-term characteristics and impact resistance, the distribution of comonomer is controlled, paying attention to the contribution of the comonomer to the high molecular weight side, and the molecular weight required by the temperature rising elution fractionation and the cross fractionation of GPC− It is known to improve the design of polyethylene by paying attention to the correlation between elution temperature and elution amount (for example, see Patent Document 3).

  Further, mechanical properties comprising polyethylene having two molecular weight distributions and having a melt flow rate (code T) (JIS K7210-1999, code T: hereinafter referred to as “MFR5”) of 0.35 g / 10 min or less. (See, for example, Patent Document 4).

Furthermore, a composition composed of two components having different intrinsic viscosities and densities is disclosed (see, for example, Patent Document 5). When a pipe molded body is molded using this composition, the hot internal pressure is obtained as a characteristic of the pipe. It has been proposed that creep tests, tensile creep tests, tensile fatigue tests, and the like are dramatically improved over conventional materials. According to this, the density and intrinsic viscosity of a composition composed of two components of low molecular weight, high density polyethylene and high molecular weight, low density polyethylene are 0.945 to 0.970 g / cm ³ (JIS K7112-1999), 2 in the range of .41~6.3dyne / cm ^2, the compositions shear rate when shear stress of the capillary at 190 ° C. is reached ^{2.4 × 10 6 dyne / cm 2} (FI) is 350Sec ^-1 or less It is said that it is possible to form a pipe excellent in formability, pipe fatigue characteristics, and the like. Furthermore, it describes also about the polyethylene pipe and its pipe joint (for example, refer patent document 6).

  In addition, a resin composition for pipes and joints has been disclosed that is excellent in moldability and fatigue characteristics when used as a pipe and also excellent in injection moldability of joints and the like (see, for example, Patent Document 7).

Japanese Examined Patent Publication No. 61-42736 Japanese Patent Publication No. 61-43378 JP 10-17619 A JP-A-8-301933 JP-A-8-134285 Japanese Patent Laid-Open No. 9-286820 JP 2000-109521 A

  However, in Patent Documents 1 and 2, the molecular weight distribution is broadened and a copolymerizable comonomer is only introduced as a side chain during polymerization, and is insufficient for improving the long-term mechanical properties required for PE100.

  Further, the resin design in Patent Document 3 cannot obtain a polyethylene resin classified as PE100.

  Furthermore, in Patent Document 4, there is a possibility that a polyethylene resin excellent in mechanical properties and classified as PE100 may be obtained. However, the molecular weight or density is constantly increased by increasing the molecular weight or introducing a comonomer to decrease the density. It is expected that molding processability will be very poor, or that the PE100 requirement will not be met due to a decrease in density because no improvements have been made.

Furthermore, with the resin in Patent Document 5, pipe properties such as fatigue resistance are certainly improved due to an increase in molecular weight, but the molding processability is inferior, and in particular, injection molding for molding a joint becomes difficult. In addition, as can be seen from the examples where the value called the flow index (FI) is FI ≦ 350 sec ⁻¹ and the MFR of the comparative example, the resin design has been increased in molecular weight to improve the physical properties, so it is clearly molded. Inferior in workability. Further, the resin in Patent Document 5 does not necessarily satisfy the requirements of PE100.

Furthermore, Patent Document 6 describes a resin having a FI value of 100 to 400 sec ⁻¹ , but it is difficult to form a joint by a molding method in a high shear rate region by injection molding. In addition, the tie molecule existence probability is improved by increasing the lamellar thickness due to the increase in molecular weight and density. Examples of means for improving long-term mechanical properties include increasing the molecular weight and broadening the molecular weight distribution. However, simply increasing the molecular weight by such a method is not suitable for forming a pipe from the viewpoint of molding processability. . In addition, the fluidity is improved by widening the molecular weight distribution, but the properties such as elongation properties and impact properties are deteriorated. Furthermore, when extruded as a pipe, not only is the surface roughened, but the surface of the molded product is also roughened even in the injection molding of a joint.

  In addition, although the resin in Patent Document 7 satisfies the 50-year warranty as PE100, the LPL at 20 ° C. when it is 100 years is somewhat insufficient. Therefore, a design in which the creep line of the stress-fracture time is further improved is required, but the generation of KneePoint is expected in the case of simple densification, and thus a new resin design that has never been seen before is required.

  Furthermore, since the joint, which is one of the piping materials, has a complicated shape for connecting the pipes together, it is likely to be partially subjected to stress concentration due to earth pressure or the like. Thus, there is a need for a piping material that can maintain a long life even when there is stress concentration. That is, a material having a long life of Slow Crack Growth (hereinafter also referred to as “SCG”) in a hot internal pressure creep test when notched is desired.

  On the other hand, when aiming only at enhancing the longevity of SCG or improving the formability, the surface property of the formed pipe is deteriorated, and roughness and unevenness are generated. This is due to the high molecular weight of the resin and the wide molecular weight distribution, and when used as a water pipe, water accumulates in rough areas and dents, which is not preferable because it also serves as a hotbed for bacterial growth. Therefore, a material capable of forming a pipe having a smooth surface is desired.

  The present invention has been made in view of the above problems, is classified as PE100 according to the ISO 9080 standard, and is guaranteed for 100 years, and has long-term characteristics, rigidity, elongation characteristics, impact resistance, and molding under high temperature acceleration conditions. An object of the present invention is to provide a piping material, particularly a pipe and a joint, which is excellent in workability and has excellent SCG longevity and surface properties.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a polyethylene composition satisfying all specific constitutional conditions can achieve the above object, and have completed the present invention.

That is, the present invention is as follows.
[1]
A piping material containing an ethylene homopolymer and / or a polyethylene resin composition that includes a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms and satisfies the following (1) to (4).
(1) The density is 948 to 952 kg / m ³ .
(2) The melt flow rate (code T) is 0.15 g / 10 min or more and less than 0.30 g / 10 min.
(3) The molecular weight distribution is 15 or more and less than 25.
(4) In the hot internal pressure creep test at 20 ° C. specified by ISO 9080, the ratio of the slope of the plot line of the logarithm of the hoop pressure to the logarithm of the fracture time has the following relationship.
Slope less than 1,000 hours / Slope after 1,000 hours> 1.5
[2]
The polyethylene resin composition is
An ethylene homopolymer and / or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a density of 967 to 973 kg / m ³ , and a melt flow rate (Code D) of 40 to 60 g / Polyethylene resin (I) 55-60 parts by mass,
A polyethylene resin (II) which is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a density of 920 to 930 kg / m ³ , and a weight average molecular weight of 500,000 to 1,000,000. ) The piping material according to [1], including 40 to 45 parts by mass.
[3]
The polyethylene resin composition produces an ethylene homopolymer in the first stage polymerization tank, and produces a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms in the second stage polymerization tank. The piping material according to [1] or [2], which is obtained by a polymerization method.
[4]
The ethylene homopolymer and / or the copolymer is composed of 1 mol of an organomagnesium compound (i) soluble in a hydrocarbon solvent represented by the following formula (1) and a chlorosilane compound (ii) represented by the following formula (2). ) 0.01-100 mol is reacted to obtain a solid (A-1a),
0.01-1 mol of alcohol (A-2) is reacted with 1 mol of C—Mg bond contained in the solid (A-1a) to obtain a solid (A-1b),
The solid (A-1b) is reacted with an organometallic compound (A-3) represented by the following formula (3) to obtain a solid (A-1c).
The solid (A-1c) is obtained by using the polymerization catalyst containing the solid catalyst component [A] and the organoaluminum compound [B] obtained by supporting the titanium compound (A-4) on the solid (A-1c). The piping material according to any one of [1] to [3].
(Al) _a (Mg) _b (R ¹ ) _c (R ² ) _d (OR ³ ) _e Formula (1)
(In the formula (1), R ¹ , R ² and R ³ are hydrocarbon groups having 2 to 20 carbon atoms, and a, b, c, d and e are numbers satisfying the following relationship: 0 ≦ a , 0 <b, 0 ≦ c, 0 ≦ d, 0 ≦ e, 0 <c + d, 0 ≦ e / (a + b) ≦ 2, 3a + 2b = c + d + e)
H _h SiCl _i R ⁴ _{4- (h + i)} (2)
(In Formula (2), R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms, and h and i are numbers satisfying the following relationship: 0 <h, 0 <i, h + i ≦ 4)
AlR ⁵ _s Q _3-s (3)
(In formula (3), R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms, and Q is selected from the group consisting of OR ⁶ , OSiR ⁷ R ⁸ R ⁹ , NR ¹⁰ R ¹¹ , SR ¹² and halogen. R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² are hydrogen atoms or hydrocarbon groups, and s is a number that satisfies the following relationship: 0 <s <3 )
[5]
The piping material according to any one of [1] to [4], which is a pipe.
[6]
The piping material according to any one of [1] to [4], which is a joint.
[7]
The piping material according to [5], wherein the pipe is for water supply.
[8]
The piping material according to [6], wherein the joint is for water supply.

  According to the present invention, it is classified as PE100 described in the ISO 9080 standard and is guaranteed for 100 years, and has excellent long-term characteristics, rigidity, elongation characteristics, impact resistance, and molding processability under high temperature acceleration conditions. The piping material which is excellent in the longevity reinforcement and surface property of SCG can be provided.

It is a figure which shows the relationship (creep curve) of the fracture time and hoop pressure of the general polyethylene obtained by ISO9080. It is a figure which shows the relationship between the fracture time in the polyethylene resin composition of Example 1, and a hoop pressure. It is a figure which shows the relationship between the fracture time in the polyethylene resin composition of Example 2, and a hoop pressure. It is a figure which shows the relationship between the fracture time in the polyethylene resin composition of the comparative example 1, and a hoop pressure. It is a figure which shows the relationship between the fracture time in the polyethylene resin composition of the comparative example 2, and a hoop pressure. It is a figure which shows the relationship between the fracture time in the polyethylene resin composition of the comparative example 3, and a hoop pressure. It is a figure which shows the relationship between the fracture | rupture time and the hoop pressure in the SCG test using the polyethylene resin composition of Example 1, 2 and Comparative Example 1,2. It is a correlation diagram which shows the correlation of molecular weight-elution temperature-elution amount in temperature rising elution fractionation GPC cross fractionation.

  Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in more detail. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. Deformation is possible.

〔piping material〕
The piping material of the present embodiment includes a polyethylene resin composition.

[Polyethylene resin composition]
Hereinafter, the polyethylene resin composition will be described. The polyethylene resin composition used in this embodiment is
Including an ethylene homopolymer and / or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, the following (1) to (4) are satisfied.
(1) The density is 948 to 952 kg / m ³ .
(2) The melt flow rate (code T) is 0.15 g / 10 min or more and less than 0.30 g / 10 min.
(3) The molecular weight distribution is 15 or more and less than 25.
(4) In the hot internal pressure creep test at 20 ° C. specified by ISO 9080, the ratio of the slope of the plot line of the logarithm of the hoop pressure to the logarithm of the fracture time has the following relationship.
Slope less than 1,000 hours / Slope after 1,000 hours> 1.5
Hereinafter, the present invention will be described in more detail.

[(1) Density]
The density (JIS K7112-1999) of the polyethylene resin composition used in this embodiment is 948 to 952 kg / m ³ , preferably 948 to 951 kg / m ³ , and more preferably 949 to 951 kg / m ³ . . By being in such a range, the rigidity as a piping material, the environmental stress cracking resistance (ESCR) under high temperature acceleration conditions, and the elongation characteristics are more excellent. Furthermore, even when used for a long period of time, it is possible to suppress brittle fracture such as low-speed crack fracture due to generation of cracks. In particular, in the hot internal pressure creep test (high temperature acceleration condition), the creep property on the short-term side becomes higher, and on the long-term side, sudden brittle fracture not depending on the working pressure is further suppressed and the long-term property is satisfied. The density of the polyethylene resin composition can be controlled by the amount of comonomer added during polymerization. Moreover, a density can be measured by the method as described in an Example.

[(2) Melt flow rate (Code T)]
The melt flow rate (code T; hereinafter also referred to as “MFR5”) of the polyethylene resin composition used in the present embodiment is 0.15 g / 10 min or more and less than 0.30 g / 10 min, preferably 0.18 g. / 10 minutes to 0.28 g / 10 minutes, more preferably 0.20 g / 10 minutes to 0.25 g / 10 minutes. When the MFR5 is 0.15 g / 10 min or more, the molding processability is excellent, and the surface roughening at the time of pipe extrusion molding or joint injection molding is further suppressed. On the other hand, when MFR5 is less than 0.30 g / 10 min, the long-term characteristics of the hot internal pressure creep test and the long-term life of SCG are superior. In particular, water supply joints have a complicated shape to connect pipes together, and even if stress is partially concentrated on such water supply joints due to earth pressure, etc., a longer lifespan is achieved. To do. Note that high density polyethylene having an MFR5 of less than 0.15 g / 10 minutes has improved mechanical properties but poor molding processability, and surface roughness particularly during pipe extrusion and joint injection molding becomes significant. The melt flow rate of the polyethylene resin composition can be controlled by the temperature during polymerization, the amount of hydrogen to be added, and the like. The melt flow rate (code T) can be measured by the method described in the examples.

[(3) Molecular weight distribution]
The molecular weight distribution of the polyethylene resin composition of the present embodiment is a ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by gel permeation chromatography. The molecular weight distribution is 15 or more and less than 25, preferably 18 or more and 25 or less, more preferably 20 or more and 24 or less. By being in such a range, it is excellent in the long-term characteristic of a hot internal pressure creep test, and excellent in moldability. In particular, the surface of a pipe surface by extrusion molding or a joint by injection molding is excellent. The molecular weight distribution of the polyethylene resin composition can be controlled by the catalyst used, the polymerization temperature, the amount of hydrogen to be added, and the like, and can also be controlled by mixing two or more polyethylene resins having different molecular weights. Moreover, molecular weight distribution can be measured by the method as described in an Example.

  By maintaining the melt flow rate (code T) from 0.15 g / 10 min to less than 0.30 g / 10 min and Mw / Mn from 15 to less than 25, good surface properties and moldability of pipes and joints can be maintained. Long-term characteristics are improved. In addition, in the hot internal pressure creep test (SCG) when a notch is made in the pipe, it is possible to increase the knee point, which is the point of transition from ductile fracture to brittle fracture. In addition, it is superior in surface properties when pipes and joints are molded. Specifically, in the range of a melt flow rate of 0.15 g / 10 min or more and less than 0.30 g / 10 min with good long-term characteristics, the molecular weight distribution is 15 or more and less than 25, so that a higher molecular weight component can be obtained. A comonomer is introduced, and piping materials such as pipes and joints having better surface properties can be obtained while having good long-term characteristics.

  SCG, which is one of the indicators of long-term characteristics, is a useful indicator when pipes are damaged, or when considering the long-term characteristics of piping materials that are prone to stress concentration in complex shapes such as joints. It becomes. Specifically, a notch is made by the method of ISO 13479, a creep test is conducted by the method of ISO 9080, and the logarithm of the hoop pressure is plotted against the logarithm of time. At this time, a Knee Point is generated with time and a transition is made from the ductile fracture region to the brittle fracture region (see FIG. 7). The time at which this Knee Point occurs was defined as SCG. The SCG is preferably 500 hours or longer, more preferably 800 hours or longer, more preferably 1000 hours or longer, and even more preferably 2,000 hours or longer. The upper limit of SCG is not particularly limited, and the longer it is, the better.

[(4) Ratio of slope of plot line]
In the polyethylene resin composition used in the present embodiment, the logarithm (logσ) of the hoop pressure (σ) against the logarithm (logT) of the fracture time (T) is plotted in the hot internal pressure creep test at 20 ° C. specified by ISO 9080. The slope of the plotted line (logσ / logT) is different before and after 1,000 hours. The slope of less than 1,000 hours with respect to the slope of the plot line after 1,000 hours of the polyethylene resin composition is 1.5 times or more, preferably 2.0 times or more, more preferably 2.5 times or more. It is. The slope of the plot line can be obtained by the method described in the examples. In addition, the ratio of the slope of less than 1,000 hours to the slope after 1,000 hours has no particular upper limit and is preferably as high as possible.

  ISO 9080 measures stress-fracture time curves up to at least 9,000 hours, calculates long-term hydrostatic strength (LTHS) using multiple correlation average, and extrapolates minimum guaranteed stress after 50 years at 20 ° C (Refer to the circled area in FIG. 1). The lower confidence limit of the value estimated by extrapolation is called extrapolated lower confidence limit (LPL). The classification of PE 100 or the like is determined by determining whether or not this LPL is equal to or greater than the minimum required strength (MRS) defined in the standard. Therefore, the long-term slope of the creep curve at 20 ° C. within the measurement range (approximately 40 hours to 10,000 hours) is important. FIG. 1 shows a general polyethylene creep curve (20 ° C., 60 ° C., 80 ° C.) obtained by ISO9080. 1 in FIG. 1 indicates ductile fracture and means the time when ductile fracture occurred at the test hoop pressure. Further, □ indicates brittle fracture and means the time when brittle fracture occurred at the test hoop pressure. Further, Δ indicates mixed fracture, meaning that ductile fracture and brittle fracture occurred at the same time. Furthermore, ◇ indicates that the test is in progress and ◇ indicates that the test was interrupted midway.

  In the conventional polyethylene material, the slope of the creep curve in the ductile fracture region is almost constant within the measurement range. Therefore, in order to increase the minimum guaranteed stress value after 50 years obtained by extrapolation, it is conceivable to increase the density of polyethylene and shift the creep curve to the right (to the long time side). When it is raised, the amount of comonomer decreases, so that tie molecules between polyethylene crystal lamellae decrease. Therefore, in the conventional polyethylene material, brittle fracture derived from fracture between lamellae and the like occurs on the low pressure and long time side, and KneePoint appears.

  On the other hand, the polyethylene resin composition used in the present embodiment has a gentle slope after 1,000 hours compared to a slope of less than 1,000 hours, and thus can be obtained by extrapolation without increasing the density for 50 years. Later, the value of the minimum guaranteed stress after 100 years can be increased.

  In order to control the ratio of the slope below 1,000 hours to the slope after 1,000 hours to 1.5 times or more (that is, to make the slope of the region after 1,000 hours gentle), The presence of a tie molecule can be mentioned. In the region of less than 1,000 hours (high pressure region), the crystal lamella is loosened, and the molecular chain is stretched through a so-called shishikabab structure. Therefore, the strength of the lamella directly affects the slope of the creep curve. On the other hand, in the region after 1,000 hours (relatively low pressure region), not only the lamella but also the effect of the tie molecule between the lamellae is added, and as a result, the slope of the creep curve is estimated to be gentle. .

  In order to generate tie molecules between lamellae, there are methods such as increasing the molecular weight of the components in the polyethylene resin composition and introducing a comonomer into the high molecular weight polyethylene resin contained in the polyethylene resin composition. A lamella is formed by folding a polyethylene chain. The higher the molecular weight of the polyethylene resin contained in the polyethylene resin composition, the easier it is for a part of the polyethylene chain to jump out of this fold, and the more branched the comonomers are, the more molecules The chain is easy to jump out. In this way, the molecular chain jumping out from the lamella forms another layer of lamella and becomes a tie molecule that connects the lamellae. The introduction of the comonomer into the high molecular weight polyethylene component can be achieved, for example, by preparing a mixture of a high molecular weight polyethylene copolymer and a low molecular weight polyethylene (homopolymer).

  As described above, the polyethylene resin composition used in the present embodiment has a specific density, MFR5, molecular weight distribution, and a ratio of the slope of the creep curve, so that the minimum guaranteed stress after 50 years and further after 100 years is high. It exhibits excellent long-term creep characteristics, and has excellent molding processability, as well as a piping material with excellent longevity and surface properties of SCG.

  In general, as a means for improving long-term mechanical properties, there are simply increasing the molecular weight of the resin, simply widening the molecular weight distribution, etc., but such methods only increase the molecular weight and widen the molecular weight distribution. However, the moldability deteriorates, the surface of the molded product is rough due to melt fracture or polymer gel, and unevenness is generated, which appears as a surface defect particularly during pipe extrusion.

[Cross fractionation gel permeation chromatography]
In addition, the polyethylene resin composition used in the present embodiment has a molecular weight of 200,000 or more and an elution temperature of 85 in the correlation of molecular weight-elution temperature-elution amount obtained by cross-fractionation between temperature rising elution fractionation and gel permeation chromatography. It is preferable that the ratio (R, unit: wt%) of the total elution amount of elution components of elution components at or below ° C is 1.0 wt% or more, more preferably 3.0 wt% or more, still more preferably It is 4.0 wt% or more. The elution component having a molecular weight of 200,000 or more and an elution temperature of 85 ° C. or less corresponds to a component having a high molecular weight and a large amount of comonomer. Is shown. Such a polyethylene resin composition is preferable because long-term creep characteristics tend to be more excellent. The integrated elution amount (CFC volume fraction) of elution components having a molecular weight of 200,000 or more and an elution temperature of 85 ° C. or less can be measured by the temperature rising elution fractionation GPC cross fractionation described in Examples.

[Polyethylene resin]
The polyethylene resin composition used in the present embodiment includes an ethylene homopolymer and / or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. The polyethylene resin composition used in the present embodiment is preferably a mixture of a low molecular weight polyethylene resin (I) and a high molecular weight polyethylene resin (II). This may be a mixture of polyethylene resin (I) and polyethylene resin (II), or obtained by polymerizing a low molecular weight component and a high molecular weight component in multiple stages by a method called multistage polymerization. May be.

(Low molecular weight polyethylene resin (I))
The polyethylene resin (I) used in the present embodiment is not particularly limited, but specifically, an ethylene homopolymer and / or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Is mentioned. Preferably the density of the polyethylene resin (I) (JIS K7112-1999) is 967~973kg / ^{m 3,} more preferably from 969~973kg / ^{m 3,} still to be 970~973kg / ^{m 3} preferable.

When the density is 967 kg / m ³ or more, sudden brittle fracture on the long-term side hardly occurs in the hot internal pressure creep property test, and the long-term property tends to be sufficient. The polyethylene resin (I) may contain a comonomer, but is preferably a polyethylene homopolymer. In the case of a homopolymer, the melt flow rate, code D (JIS K7210-1999, code D: hereinafter also referred to as “MFR 2.16”) is in the range of 40 to 60 g / 10 minutes, so that 973 kg / It tends to be less than m ³ .

  The MFR 2.16 of the polyethylene resin (I) is preferably 40 to 60 g / 10 minutes, more preferably 42 to 58 g / 10 minutes, and further preferably 45 to 55 g / 10 minutes. Further, when the MFR 2.16 is 60 g / 10 min or less, the long-term life and elongation characteristics of the hot internal pressure creep test are improved, the impact resistance is excellent, and the surface property during molding tends to be excellent. . When MFR 2.16 is 40 g / 10 min or more, molding processability tends to be excellent, and injection molding is particularly easy.

  The weight average molecular weight of the polyethylene resin (I) is preferably 5,000 to 300,000, more preferably 10,000 to 100,000, and 25,000 to 70,000. Further preferred. When the weight average molecular weight is 5,000 or more, there is no stickiness or deterioration of long-term characteristics, and the dispersibility with high molecular weight components tends to be excellent. Moreover, it exists in the tendency for a moldability to become favorable because a weight average molecular weight is 500,000 or less. The weight average molecular weight of the polyethylene resin (I) can be measured by gel permeation chromatography (GPC) when polymer components and low molecular components are separately polymerized and mixed. On the other hand, in the polymerization by multistage polymerization, since the low molecular weight polyethylene resin component cannot be isolated and the weight average molecular weight cannot be measured, the conversion is performed by the conversion method described later.

(High molecular weight polyethylene resin (II))
On the other hand, the polyethylene resin (II) used in the present embodiment is not particularly limited, but specifically, it is preferably a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Density polyethylene resin (II) (JIS K7112-1999) is preferably 920~930kg / ^{m 3,} it is more preferably 922~930kg / ^{m 3,} a 924~930kg / ^{m 3} Further preferred. When the density is 920 kg / m ³ or more, the molded pipe tends to have sufficient rigidity. In addition, by being 930 kg / m ³ or less, ESCR and elongation characteristics under high temperature acceleration conditions are not deteriorated, and brittle fractures such as generation of cracks and low-speed crack fractures due to long-term use are further suppressed. It tends to be.

  The weight average molecular weight of the polyethylene resin (II) is preferably 500,000 to 1,000,000, more preferably 600,000 to 950,000, and 700,000 to 900,000. More preferably. When the weight average molecular weight is 500,000 or more, the molding processability is good, the long-term life and elongation characteristics of the hot internal pressure creep are good, and the impact resistance tends to be excellent. Further, when the weight average molecular weight is 1,000,000 or less, the mechanical properties are sufficient, and the moldability, particularly the injection moldability, tends to be good.

  The weight average molecular weight of the polyethylene resin (II) can be measured by gel permeation chromatography (GPC) when polymer components and low molecular components are separately polymerized and mixed. On the other hand, in polymerization by multistage polymerization, since a high molecular weight polyethylene resin component cannot be isolated and a weight average molecular weight cannot be measured, conversion is performed by the following method.

(Conversion method)
i) Conversion from MFR 2.16 of polyethylene resin (I) component and polyethylene resin composition to MFR 2.16 of polyethylene resin (II) component.
When mixing polyethylene resins having different MFR (MFR1st, MFR2nd), it is known that MFRfinal after mixing can be calculated as follows.
(MFRfinal) ^-0.175 =
(1-R) × (MFR1st) ^−0.175 + R × (MFR2nd) ^−0.175 (Equation 1)

  Here, MFR2.16 of polyethylene resin (I) component is MFR1st, MFR2.16 of polyethylene resin (II) component is MFR2nd, MFR2.16 of polyethylene resin composition is MFRfinal, polyethylene resin (II) component amount and polyethylene resin ( I) The ratio (mixing ratio) of the polyethylene resin (II) component amount to the sum of the component amounts is represented by R.

According to (Equation 1), MFR2nd of the polyethylene resin (II) component can be expressed as follows.
MFR2nd = (((MFRfinal) ^−0.175 −
(1-R) × (MFR1st) ^−0.175 ) / R) ^{−1 / 0.175} (Expression 2)

ii) Conversion of polyethylene resin (II) component from MFR 2.16 to the respective weight average molecular weight.
It is known that MFR 2.16 and weight average molecular weight have the following relationship.
Mw × 10 ⁻⁴ = 13.291 × MFR ^{2.16 −0.2842} (Equation 3)

From the above, the weight average molecular weight Mw is expressed as follows. In addition, although the conversion method of the weight average molecular weight of polyethylene resin (II) was shown above, the conversion method of the weight average molecular weight of polyethylene resin (I) component can be performed similarly.
Mw = 13.291 × 10 ⁻⁴ × ((((MFRfinal) ^−0.175 −
(1-R) × (MFR1st) ^−0.175 ) / R) ^{−1 / 0.175} ) ^−0.2842 (Equation 4)

  As described above, in order to generate tie molecules between crystal lamellae, it is preferable that the molecular chain protruding from the lamella has a high molecular weight. Therefore, the polyethylene resin (II) is preferably a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

  Although it does not specifically limit as a C3-C20 alpha-olefin which can be used in this embodiment, Specifically, a propylene, 1-butene, 1-pentene, 3-methyl- 1-butene, 3- Methyl-1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-icocene, cyclopentene, cyclohexene, Cycloheptene, norbornene, dicyclopentadiene, 5-methyl-2-norbornene, tetracyclododecene, 2-methyl-1,4: 5,8-dimethano-1,2,3,4,4a, 5,8,8a -Octahydronaphthalene, styrene, vinylcyclohexane, 1,3-butadiene, 1,4-pentadiene, 1,5-hexa Ene, 1,4-hexadiene, 1,7-octadiene and cyclohexadiene, and the like.

  The α-olefin content is not particularly limited, but is preferably 0.30 to 1.50 mol%, more preferably 0.40 to 1.20 mol%, and 0.50 to 1.00 mol%. More preferably. Here, the α-olefin content is the total content of α-olefin in the polyethylene resin. When the α-olefin content is 0.30 mol% or more, ESCR and elongation characteristics under high temperature acceleration conditions tend to be improved. Moreover, when the α-olefin content is 1.50 mol% or less, the polyethylene resin can be easily produced, and the resulting composition tends to suppress gel generation and improve mechanical properties.

  Moreover, it is preferable to manufacture the polyethylene resin composition used by this embodiment by the multistage polymerization superposed | polymerized using an at least 2 superposition | polymerization device. In particular, it is obtained by a two-stage polymerization method in which an ethylene homopolymer is produced in the first stage polymerization tank, and a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms is produced in the second stage polymerization tank. It is preferable that Polyethylene with excellent long-term properties and moldability by polymerizing polyethylene with different molecular weights in multiple polymerization vessels by multi-stage polymerization, and widening the molecular weight distribution of the entire polyethylene resin crude product mixed with the polyethylene A resin can be obtained. Here, since it is preferable that the molecular weight of polyethylene polymerized in each polymerizer is different, when comparing the molecular weight of the component polymerized in each polymerizer, the lower molecular weight side is the polyethylene resin low molecular weight component, molecular weight The larger side is called a polyethylene resin high molecular weight component. When polymerization is performed by multistage polymerization, polymerization is performed in the first-stage polymerization apparatus, transferred to the polymerization apparatus in the second and subsequent stages, and polymerization is performed. Polyethylene resins having different molecular weights are polymerized in two or more polymerization apparatuses. There is a method of obtaining a polyethylene resin by slurry mixing, powder mixing, or pellet mixing later, among which continuous polymerization is preferable. Alternatively, the polyethylene low molecular weight component may be polymerized in the first stage and then the polyethylene high molecular weight component may be polymerized in the second stage or after the high molecular weight component is polymerized in the first stage. May be polymerized. The polyethylene resin is preferably produced by polymerizing ethylene and one or more comonomers selected from α-olefins having 3 to 20 carbon atoms in such a ratio that the desired density is obtained. . At that time, in order to obtain a desired molecular weight and MFR, a molecular weight regulator such as hydrogen may be used.

  In the case where the polyethylene resin composition used in the present embodiment includes the polyethylene resin (I) and the polyethylene resin (II), the ratio of the polyethylene resin (I) and the polyethylene resin (II) is as follows: It is preferably 55 to 60 parts by mass, and more preferably 57 to 59 parts by mass. Moreover, it is preferable that it is 40-45 mass parts, and, as for polyethylene resin (II), it is more preferable that it is 41-43 mass parts. By setting the ratio of the polyethylene resin (II) to 40 parts by mass or more and the ratio of the polyethylene resin (I) to 60 parts by mass or less, rough skin when a pipe is molded is suppressed, the surface property is excellent, and the extruder It tends to be able to effectively suppress the eyes and eyes generated in the dice. Further, when the proportion of the polyethylene resin (II) is 45 parts by mass or less and the proportion of the polyethylene resin (I) is 55 parts by mass or more, the high molecular weight component becomes sufficient, and the lifetime on the long side of the hot internal pressure creep is increased. In addition, elongation characteristics and impact resistance tend to be sufficient. For example, bringing the mixing ratio close to 50 parts by mass without changing the melt flow rate of the entire polyethylene resin composition decreases the molecular weight of the high molecular weight component that affects rough skin and increases the molecular weight of the low molecular weight component that affects the eyes. Means that.

  When the low molecular weight component contained in the resin is reduced, the generation of the eye can be suppressed, and when the low molecular weight component is increased, the melt flow rate is increased and the extrudability and rough skin property tend to be improved. In addition, when the low molecular weight component is decreased, the molecular weight of the high molecular weight component is lowered or the ratio of the high molecular weight component is lowered to ensure moldability and maintain the melt flow rate as the composition. There is a tendency to be able to. Furthermore, mechanical properties and long-term physical properties tend to be improved by increasing the molecular weight of the high molecular weight component or increasing the ratio of the high molecular weight component. As described above, it is preferable to balance both components such as the low molecular weight component, the molecular weight and molecular weight distribution of each of the high molecular weight components, the composition ratio of both components, and the like.

  The density and melt flow rate of each of the polyethylene resin (I) and the polyethylene resin (II) can be controlled by changing the polymerization conditions (polymerization temperature, pressure, hydrogen concentration to be added, comonomer amount, etc.).

[Method for producing polyethylene resin composition]
The ethylene homopolymer and / or copolymer contained in the polyethylene resin composition used in the present embodiment, specifically, the polyethylene resin (I) and / or the polyethylene resin (II) are a Ziegler catalyst, a Philips catalyst, Alternatively, it can be produced by a vessel type slurry polymerization method using a supported geometrically constrained single site catalyst. Among these, it is particularly preferable to use a Ziegler catalyst and a supported geometrically constrained single site catalyst.

  The Ziegler catalyst in the present embodiment is an olefin polymerization catalyst having a titanium chloride compound and an alkylaluminum compound as essential components (see, for example, P.836 of Riken Dictionary 5th edition (Iwanami Shoten)). In the present embodiment, the method for producing a Ziegler catalyst is not particularly limited, but a Ziegler catalyst produced by the following production method is preferred.

  The ethylene homopolymer and / or copolymer contained in the polyethylene resin composition used in the present embodiment is produced by a Ziegler catalyst containing a solid catalyst component [A] and an organoaluminum compound [B]. preferable.

Here, the solid catalyst component [A] is composed of 1 mol of an organomagnesium compound (i) soluble in a hydrocarbon solvent represented by the following formula (1) and a chlorosilane compound (ii) 0. A solid (A-1a) is obtained by reacting 01 to 100 mol, and 0.01 to 1 mol of alcohol (A-2) is added to 1 mol of C-Mg bond contained in the solid (A-1a). A solid (A-1b) is obtained by reaction, and the solid (A-1b) is further reacted with an organometallic compound (A-3) represented by the following formula (3) to give a solid (A-1c). And a Ziegler catalyst for olefin polymerization produced by supporting the organometallic compound represented by the following formula (5) and a titanium compound (A-4) on the solid (A-1c) as necessary. It is preferable that Although it does not specifically limit as a titanium compound, Specifically, the titanium compound (A-4) represented by following formula (4) is preferable.
(Al) _a (Mg) _b (R ¹ ) _c (R ² ) _d (OR ³ ) _e (1)
(In the formula (1), R ¹ , R ² and R ³ are hydrocarbon groups having 2 to 20 carbon atoms, and a, b, c, d and e are numbers satisfying the following relationship: 0 ≦ a 0 <b, 0 ≦ c, 0 ≦ d, 0 ≦ e, 0 <c + d, 0 ≦ e / (a + b) ≦ 2, 3a + 2b = c + d + e)
H _h SiCl _i R ⁴ _{(4- (h + i))} (2)
(In Formula (2), R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms, and h and i are numbers satisfying the following relationship: 0 <h, 0 <i, h + i ≦ 4).
AlR ⁵ _s Q _3-s (3)
(In formula (3), R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms, and Q is selected from the group consisting of OR ⁶ , OSiR ⁷ R ⁸ R ⁹ , NR ¹⁰ R ¹¹ , SR ¹² and halogen. R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² are hydrogen atoms or hydrocarbon groups, and s is a number that satisfies the following relationship: 0 <s <3 )
Ti (OR ⁵ ) _j X _(4-j) (4)
(In Formula (4), j is a real number of 0 to 4, R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms, and X is a halogen atom.)

  First, the organic magnesium compound (i) will be described. The organomagnesium compound (i) is shown as a complex form of organomagnesium soluble in an inert hydrocarbon solvent, but includes all dihydrocarbylmagnesium compounds and complexes of this compound with other metal compounds. To do. The symbols a, b, c, d and e in the formula (1) satisfy the relational expression 3a + 2b = c + d + e, which indicates the stoichiometry between the valence of the metal atom and the substituent.

In the above formula, the hydrocarbon group having 2 to 20 carbon atoms represented by R ¹ and R ² is not particularly limited, and specific examples thereof include an alkyl group, a cycloalkyl group, and an aryl group. Methyl, ethyl, propyl, butyl, propyl, hexyl, octyl, decyl, cyclohexyl, phenyl group and the like. Of these, R ¹ and R ² are each preferably an alkyl group.

The ratio b / a of magnesium to aluminum is not particularly limited, but is preferably 0.1 to 30, and more preferably 0.5 to 10. Further, when a = 0, for example, R ¹ is preferably 1-methylpropyl or the like, whereby the organomagnesium compound (i) tends to be more soluble in an inert hydrocarbon solvent. In Formula (1), when a = 0, R ¹ and R ² satisfy any one of the following three groups (1), (2), and (3): preferable.

It is preferable that at least ^{one of} group (1) R ¹ and R ² is a secondary or tertiary alkyl group having 4 to 6 carbon atoms, and R ¹ and R ² are both 4 to 6 carbon atoms, More preferably, one is a secondary or tertiary alkyl group.
Group (2) R ¹ and R ² are preferably alkyl groups different from each other in carbon number, R ¹ is an alkyl group having 2 or 3 carbon atoms, and R ² is an alkyl group having 4 or more carbon atoms. More preferably.
Preferably the group (3) at least one of R ^1, R ² is a hydrocarbon group having 6 or more carbon atoms, that the sum of the number of carbon atoms contained in R ^1, R ² is an alkyl group of 12 or more More preferred.

  Hereinafter, these groups are specifically shown. Specific examples of the secondary or tertiary alkyl group having 4 to 6 carbon atoms in the group (1) include 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2 -Ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 2-methyl-2-ethylpropyl group and the like can be mentioned. Of these, a 1-methylpropyl group is preferable.

  Next, in the group (2), specific examples of the alkyl group having 2 or 3 carbon atoms include ethyl, 1-methylethyl, and propyl groups, and an ethyl group is particularly preferable. Further, the alkyl group having 4 or more carbon atoms is not particularly limited, and specific examples thereof include butyl, pentyl, hexyl, heptyl, octyl group and the like. Of these, butyl and hexyl groups are preferable.

  Furthermore, in the group (3), the hydrocarbon group having 6 or more carbon atoms is not particularly limited, and specific examples include hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl group and the like. Among the hydrocarbon groups, an alkyl group is preferable, and among the alkyl groups, hexyl and octyl groups are particularly preferable.

  In general, when the number of carbon atoms contained in the alkyl group increases, it tends to be easily dissolved in an inert hydrocarbon solvent. However, it is preferable to use an alkyl group having a chain length as necessary in order to increase the viscosity of the solution. The organomagnesium compound (i) is used in the state of an inert hydrocarbon solution. Even if trace amounts of Lewis basic compounds such as ethers, esters and amines are contained or remain in the solution. It can be used without any problem. In addition, although it does not specifically limit as an inert hydrocarbon solvent in this embodiment, Specifically, Aliphatic hydrocarbons, such as pentane, hexane, and heptane; Aromatic hydrocarbons, such as benzene and toluene; And cyclohexane, methyl Examples include alicyclic hydrocarbons such as cyclohexane.

Next, the alkoxy group (OR ³ ) will be described. Although it does not specifically limit as a C2-C20 hydrocarbon group represented by R < ³ >, Specifically, a C2-C20 alkyl group or an aryl group is preferable, and a C3-10 alkyl group is preferable. Or an aryl group is more preferable. Although it does not specifically limit as a C2-C20 alkyl group or an aryl group, Specifically, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 1,1-dimethylethyl, pentyl Hexyl, 2-methylpentyl, 2-ethylbutyl, 2-ethylpentyl, 2-ethylhexyl, 2-ethyl-4-methylpentyl, 2-propylheptyl, 2-ethyl-5-methyloctyl, octyl, nonyl, decyl, A phenyl, a naphthyl group, etc. are mentioned. Of these, butyl, 1-methylpropyl, 2-methylpentyl and 2-ethylhexyl groups are more preferred.

In this embodiment, the method for synthesizing the organomagnesium compound (i) is not particularly limited, but the formulas R ¹ MgX and R ¹ ₂ Mg (R ¹ is the same group as described above, and X is a halogen atom. Inorganic hydrocarbon selected from the group consisting of the organic magnesium compound selected from the group consisting of the formulas AlR ² ₃ and AlR ² ₂ H (wherein R ² is the same group as described above). It can obtain by making it react at the temperature of 25 to 150 degreeC in a solvent. In addition, if necessary, this reaction is followed by an alcohol having a hydrocarbon group represented by R ³ (R ³ is the same group as described above), or an R ³ soluble in an inert hydrocarbon solvent. The method of making it react with the alkoxymagnesium compound and / or alkoxyaluminum compound which have the hydrocarbon group represented by these is preferable.

  Among these, when reacting an organomagnesium compound soluble in an inert hydrocarbon solvent with an alcohol, the order of the reaction is not particularly limited, and a method of adding alcohol to the organomagnesium compound, organomagnesium in the alcohol. Either a method of adding a compound or a method of adding both at the same time can be used. In the present embodiment, the reaction ratio between the organomagnesium compound soluble in the inert hydrocarbon solvent and the alcohol is not particularly limited. However, as a result of the reaction, the alkoxy group-containing organomagnesium compound has an alkoxy group with respect to all metal atoms. The molar composition ratio e / (a + b) is 0 ≦ e / (a + b) ≦ 2, and preferably 0 ≦ e / (a + b) <1.

Next, the chlorosilane compound (ii) will be described. The chlorosilane compound (ii) is a silicon chloride compound having at least one Si—H bond represented by the formula (2).
H _h SiCl _i R ⁴ _{(4- (h + i))} (2)
(In Formula (2), R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms, and h and i are numbers satisfying the following relationship: 0 <h, 0 <i, h + i ≦ 4).

Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ⁴ in formula (2) is not particularly limited, specifically, aliphatic hydrocarbon group, alicyclic hydrocarbon group, or an aromatic hydrocarbon Examples thereof include a hydrogen group, and examples thereof include methyl, ethyl, propyl, 1-methylethyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, and phenyl groups. Among these, an alkyl group having 1 to 10 carbon atoms is preferable, and an alkyl group having 1 to 3 carbon atoms such as methyl, ethyl, propyl, and 1-methylethyl group is more preferable. H and i are numbers greater than 0 satisfying the relationship of h + i ≦ 4, and i is preferably 2 to 3.

Such chlorosilane compound (ii), it is not particularly limited, _{specifically, HSiCl 3, HSiCl 2 CH 3} , HSiCl 2 C 2 H 5, HSiCl 2 (C 3 H 7), HSiCl 2 (2- _{C 3 H 7), HSiCl 2} (C 4 H 9), HSiCl 2 (C 6 H 5), HSiCl 2 (4-Cl-C 6 H 4), HSiCl 2 (CH = CH 2), HSiCl 2 (CH ₂ C ₆ H ₅ ), HSiCl ₂ (1-C ₁₀ H ₇ ), HSiCl ₂ (CH ₂ CH═CH ₂ ), H ₂ SiCl (CH ₃ ), H ₂ SiCl (C ₂ H ₅ ), HSiCl (CH _{3) 2, HSiCl (C 2} H 5) 2, HSiCl (CH 3) (2-C 3 H 7), HSiCl (CH 3) (C 6 H 5), HSiCl (C 6 H ) _2, and the like. Among these, HSiCl ₃ , HSiCl ₂ CH ₃ , HSiCl (CH ₃ ) ₂ , and HSiCl ₂ C ₂ H ₅ are preferable, and HSiCl ₃ and HSiCl ₂ CH ₃ are more preferable. A chlorosilane compound may be used individually by 1 type, or may use 2 or more types together.

  Next, the reaction between the organomagnesium compound (i) and the chlorosilane compound (ii) will be described. In the reaction, the chlorosilane compound (ii) is previously treated with an inert hydrocarbon solvent; chlorinated hydrocarbons such as 1,2-dichloroethane, o-dichlorobenzene and dichloromethane; ether-based media such as diethyl ether and tetrahydrofuran; or a mixed medium thereof. It is preferable to use after diluting with an inert hydrocarbon solvent in view of the performance of the catalyst. The reaction ratio between the organomagnesium compound (i) and the chlorosilane compound (ii) is not particularly limited, but the silicon atoms contained in the chlorosilane compound (ii) with respect to 1 mol of magnesium atoms contained in the organomagnesium compound (i) are 0.01 mol to It is preferably 100 mol or less, and more preferably 0.1 mol to 10 mol.

  There is no restriction | limiting in particular about the reaction method of organomagnesium compound (i) and chlorosilane compound (ii), The method of simultaneous addition which reacts, introducing organomagnesium compound (i) and chlorosilane compound (ii) into a reactor simultaneously. , A method of introducing the organomagnesium compound (i) into the reactor after the chlorosilane compound (ii) is previously charged into the reactor, or a chlorosilane compound (ii) after the organomagnesium compound (i) is charged into the reactor in advance However, it is preferable to introduce the organomagnesium compound (i) into the reactor after the chlorosilane compound (ii) is charged into the reactor in advance. The solid (A-1a) obtained by the above reaction is preferably separated by filtration or decantation, and then thoroughly washed with an inert hydrocarbon solvent to remove unreacted products or by-products. .

  The reaction temperature of the organomagnesium compound (i) and the chlorosilane compound (ii) is not particularly limited, but is preferably 25 ° C to 150 ° C, more preferably 40 ° C to 150 ° C, and more preferably 50 ° C to 150 ° C. More preferably, it is 150 degreeC. In the simultaneous addition method in which the organomagnesium compound (i) and the chlorosilane compound (ii) are simultaneously introduced into the reactor and reacted, the temperature of the reactor is adjusted to a predetermined temperature in advance, and the simultaneous addition is performed in the reactor. It is preferable to adjust the reaction temperature to a predetermined temperature by adjusting the temperature of the above to a predetermined temperature. In the method in which the organomagnesium compound (i) is introduced into the reactor after the chlorosilane compound (ii) is charged into the reactor in advance, the temperature of the reactor charged with the chlorosilane compound (ii) is adjusted to a predetermined temperature, It is preferable to adjust the reaction temperature to a predetermined temperature by adjusting the temperature in the reactor to a predetermined temperature while introducing the magnesium compound (i) into the reactor. In the method of introducing the chlorosilane compound (ii) into the reactor after the organomagnesium compound (i) is charged in the reactor in advance, the temperature of the reactor charged with the organomagnesium compound (i) is adjusted to a predetermined temperature, The reaction temperature can be adjusted to a predetermined temperature by adjusting the temperature in the reactor to a predetermined temperature while introducing the chlorosilane compound (ii) into the reactor.

The reaction between the organomagnesium compound (i) and the chlorosilane compound (ii) can also be performed in the presence of a solid. This solid may be either an inorganic solid or an organic solid, but it is preferable to use an inorganic solid. The following are mentioned as an inorganic solid.
(I) Inorganic oxide (II) Inorganic carbonate, silicate, sulfate (III) Inorganic hydroxide (IV) Inorganic halide (V) Double salt, solid solution, or mixture comprising (I) to (IV)

Specific examples of the inorganic solid are not particularly limited. Specifically, silica, alumina, silica / alumina, hydrated alumina, magnesia, tria, titania, zirconia, calcium phosphate / barium sulfate, calcium sulfate, magnesium silicate, magnesium · Calcium, aluminum silicate [(Mg · Ca) O · Al ₂ O ₃ · 5SiO ₂ · nH ₂ O], potassium silicate · aluminum [K ₂ O · 3Al ₂ O ₃ · 6SiO ₂ · 2H ₂ O], magnesium silicate Examples include iron [(Mg · Fe) ₂ SiO ₄ ], aluminum silicate [Al ₂ O ₃ · SiO ₂ ], calcium carbonate, magnesium chloride, magnesium iodide, and the like. Of these, silica, silica / alumina, and magnesium chloride are preferable. The specific surface area of the inorganic solid is preferably 20 m ² / g or more, more preferably 90 m ² / g or more.

The solid (A-1a) obtained as described above is further reacted with an alcohol (A-2) to obtain a solid (A-1b). Although it does not specifically limit as alcohol (A-2) used in this case, Specifically, C1-C20 saturated or unsaturated alcohol can be illustrated, for example, methyl alcohol, ethyl alcohol, Propyl alcohol, iso-propyl alcohol, butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, iso-amyl alcohol, sec-amyl alcohol, tert-amyl alcohol, hexyl alcohol, cyclo Examples include hexanol, phenol, cresol and the like. Of these, C ₃ to C ₈ linear alcohols, iso-butyl alcohol, and iso-amyl alcohol are preferred.

  Next, the amount of alcohol (A-2) used is preferably 0.01 to 1 mol, more preferably 0.05 to 0.5 mol, per 1 mol of C-Mg bonds contained in the solid (A-1a). More preferably, it is the range of 0.1-0.25 mol. The reaction of the solid (A-1a) and the alcohol (A-2) can be performed in the presence or absence of an inert medium. As the inert medium, any of the above-described aliphatic, aromatic, and alicyclic hydrocarbons may be used. Although the temperature at the time of reaction is not specifically limited, Preferably it can implement at room temperature-200 degreeC.

Next, the solid (A-1b) obtained by the reaction between the solid (A-1a) and the alcohol (A-2) is reacted with the organometallic compound (A-3) represented by the following formula (3). Thus, a solid (A-1c) can be obtained.
AlR ⁵ _s Q _3-s (3)
(In formula (3), R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms, and Q is selected from the group consisting of OR ⁶ , OSiR ⁷ R ⁸ R ⁹ , NR ¹⁰ R ¹¹ , SR ¹² and halogen. R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² are hydrogen atoms or hydrocarbon groups, and s is a number that satisfies the following relationship: 0 <s <3 ).

  The organometallic compound (A-3) is not particularly limited, and specifically, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triiso-butylaluminum, tri-n-amyl. Trialkylaluminum such as aluminum, triiso-amylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-n-decylaluminum; diethylaluminum chloride, ethylaluminum dichloride, diiso-butylaluminum chloride, ethylaluminum sesquichloride Aluminum halides such as diethylaluminum bromide; alkoxyaluminums such as diethylaluminum ethoxide and diiso-butylaluminum butoxide ; Dimethylhydrosiloxy aluminum dimethyl, ethyl methyl hydro siloxy aluminum diethyl, ethyl dimethylsiloxy aluminum diethyl acyloxyalkyl aluminum and the like; and mixtures thereof. Among these, aluminum halide is preferable, and dimethylaluminum chloride, methylaluminum dichloride, diethylaluminum chloride, ethylaluminum dichloride, dipropylaluminum chloride, and dibutylaluminum chloride are more preferable.

  The reaction between the solid (A-1b) obtained by the reaction between the solid (A-1a) and the alcohol (A-2) and the organometallic compound (A-3) is preferably performed using an inert reaction medium. Can do. Such an inert reaction medium is not particularly limited, and specifically includes aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as benzene and toluene; alicyclic carbonization such as cyclohexane and methylcyclohexane. Hydrogen etc. are mentioned. Of these, aliphatic hydrocarbons are preferred. The amount of the organometallic compound (A-3) used is preferably 0.5 mol or less, particularly preferably 0.1 mol or less, per mol of C—Mg bonds contained in the solid component (A-1a). Although it does not specifically limit about reaction temperature, It is preferable to carry out in the range of room temperature-150 degreeC.

Next, the titanium compound (A-4) will be described. In the present embodiment, the titanium compound (A-4) is preferably a titanium compound represented by the above formula (4).
Ti (OR ⁵ ) _j X _(4-j) Expression (4)
(In Formula (4), j is a real number of 0 to 4, R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms, and X is a halogen atom.)

Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ^5, is not particularly limited, specifically, methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, Aliphatic hydrocarbon groups such as allyl groups; alicyclic hydrocarbon groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl groups; aromatic hydrocarbon groups such as phenyl and naphthyl groups. Among these, an aliphatic hydrocarbon group is preferable. Examples of the halogen represented by X include chlorine, bromine and iodine, with chlorine being preferred. A titanium compound (A-4) can be used individually by 1 type, or can be used in mixture of 2 or more types.

  Although there is no restriction | limiting in particular in the usage-amount of a titanium compound (A-4), 0.01-20 are preferable by molar ratio with respect to the magnesium atom contained in solid (A-1c), and 0.05-10 are especially preferable.

  Although it does not specifically limit about reaction temperature of solid (A-1c) and a titanium compound (A-4), It is preferable to carry out in the range of 25 to 150 degreeC.

  In the present embodiment, the method for supporting the titanium compound (A-4) on the solid (A-1c) is not particularly limited, and an excess of the titanium compound (A-4) is reacted with the solid (A-1c). Although the method of carrying | supporting a titanium compound (A-4) efficiently by using the method to make or a 3rd component may be used, a titanium compound (A-4) and an organometallic compound (A-5) A method of supporting by reaction is preferred.

Next, the organometallic compound (A-5) will be described. As (A-5), what is represented by following formula (5) or formula (6) is preferable.
(M ¹ ) _a (Mg) _b (R ¹ ) _c (R ² ) _d Y _e (5)
(In Formula (5), M ¹ is a metal atom other than magnesium selected from the group consisting of Group 1, Group 2, Group 12, and Group 13 of the Periodic Table, and R ¹ and R ² are those described above. Y is alkoxy, siloxy, allyloxy, amino, amide, —N═C—R ⁶ , R ⁷ , —SR ⁸ , β-keto acid residue (where R ⁶ , R ⁷ and R ⁸ are Represents a hydrocarbon group having 1 to 20 carbon atoms, and when e is 2 or more, Y may be different from each other), and a, b, c, d and e are in the following relationship: 0 ≦ a, 0 <b, 0 ≦ c, 0 ≦ d, 0 ≦ e, 0 <c + d, 0 ≦ e / (a + b) ≦ 2, f × a + 2b = c + d + e (where f Is the valence of M ¹ ))
M ² R ⁹ _k Q _(m−k) (6)
(In Formula (6), M ² is a metal atom selected from the group consisting of Group 1, Group 2, Group 12, Group 13 of the Periodic Table, and R ⁹ is a hydrocarbon having 1 to 20 carbon atoms. Q represents a group selected from the group consisting of OR ¹⁰ , OSiR ¹¹ R ¹² R ¹³ , NR ¹⁴ R ¹⁵ , SR ¹⁶ and halogen, and R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are a hydrogen atom or a hydrocarbon group, k is a real number larger than 0, and m is a valence of M ^2. )

  Hereinafter, the organometallic compounds represented by the above formulas (5) and (6) are referred to as an organometallic compound (A-5a) and an organometallic compound (A-5b), respectively.

  First, the organometallic compound (A-5a) will be described. The usage-amount of an organometallic compound (A-5a) is 0.1-10 in the molar ratio of the magnesium atom contained in the organometallic compound (A-5a) with respect to the titanium atom contained in a titanium compound (A-4). It is preferable that it is 0.5-5. The temperature of the reaction between the titanium compound (A-4) and the organometallic compound (A-5a) is not particularly limited, but is preferably -80 ° C to 150 ° C, and is in the range of -40 ° C to 100 ° C. More preferably.

Although there is no restriction | limiting in particular about the density | concentration at the time of use of an organometallic compound (A-5a), It is preferable that it is 0.1 mol / L-2 mol / L on the basis of the magnesium atom contained in an organometallic compound (A-5a). More preferably, it is 0.5 mol / L to 1.5 mol / L. In addition, it is preferable to use an inert hydrocarbon solvent for the dilution of the organometallic compound (A-5a).

  There are no particular restrictions on the order of addition of the titanium compound (A-4) and the organometallic compound (A-5a) to the solid (A-1c), and the organometallic compound (A-5a) follows the titanium compound (A-4). ), The organometallic compound (A-5a) is added followed by the titanium compound (A-4), and the titanium compound (A-4) and the organometallic compound (A-5a) are added simultaneously. Although a method is also possible, the method of adding a titanium compound (A-4) and an organometallic compound (A-5a) simultaneously is preferable. The reaction between the titanium compound (A-4) and the organometallic compound (A-5a) is carried out in an inert hydrocarbon solvent, but it is preferable to use an aliphatic hydrocarbon solvent such as hexane or heptane. The catalyst thus obtained is used as a slurry solution using an inert hydrocarbon solvent.

Next, the organometallic compound (A-5b) will be described. The organometallic compound (A-5b) is an organometallic compound represented by the formula (6). In the above formula (6), M ² is a metal atom selected from the group consisting of Group 1, Group 2, Group 12, Group 13 of the Periodic Table, and is not particularly limited. Sodium, potassium, beryllium, magnesium, boron, aluminum, zinc and the like. Among these, magnesium, boron, and aluminum are preferable. Although it does not specifically limit as a C1-C20 hydrocarbon group represented by R < ⁹ >, Specifically, an alkyl group, a cycloalkyl group, or an aryl group is mentioned, For example, methyl, ethyl, propyl, butyl , Pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl group and the like. Among these, an alkyl group is preferable.

Q represents a group selected from the group consisting of OR ¹⁰ , OSiR ¹¹ R ¹² R ¹³ , NR ¹⁴ R ¹⁵ , SR ¹⁶ and halogen, and R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ is a hydrogen atom or a hydrocarbon group, and Q is preferably halogen.

  The organometallic compound (A-5b) is not particularly limited, and specifically, methyllithium, butyllithium, methylmagnesium chloride, methylmagnesium bromide, methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide. , Ethylmagnesium iodide, butylmagnesium chloride, butylmagnesium bromide, butylmagnesium iodide, dibutylmagnesium, dihexylmagnesium, triethylboron, trimethylaluminum, dimethylaluminum bromide, dimethylaluminum chloride, dimethylaluminum methoxide, methylaluminum dichloride, methylaluminum Sesquichloride, triethylaluminum, diethylaluminum chloride , Diethylaluminum bromide, diethylaluminum ethoxide, ethylaluminum dichloride, ethylaluminum sesquichloride, tripropylaluminum, tributylaluminum, tri (2-methylpropyl) aluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, etc. It is done. Among these, an organoaluminum compound is preferable. Moreover, these compounds can be used individually by 1 type, or 2 or more types can be mixed and used for them. k is a real number larger than 0, and is preferably a real number larger than 0.5.

The amount of the organic metal compound (A-5b) is 0.1 to 10 at a molar ratio of ^{M 2} atoms contained in the titanium compound organometallic compound to titanium atom contained in the (A-4) (A- 5b) It is preferable that it is, and it is more preferable that it is 0.5-5. The temperature of the reaction between the titanium compound (A-4) and the organometallic compound (A-5b) is not particularly limited, but is preferably 20 ° C to 150 ° C, and more preferably 40 ° C to 100 ° C. .

Although there is no restriction | limiting in particular about the density | concentration at the time of use of an organometallic compound (A-5b), It is 0.1 mol / L- ² mol / L on the basis of M2 atom contained in an organometallic compound (A-5b). Preferably, it is 0.5 mol / L to 1.5 mol / L. In addition, it is preferable to use an inert hydrocarbon solvent for the dilution of the organometallic compound (A-5b).

  There are no particular limitations on the method of adding the titanium compound (A-4) and the organometallic compound (A-5b) to the solid (A-1c). First, the titanium compound (A-4) is added, followed by the organic compound. Method of adding metal compound (A-5b), first adding organometallic compound (A-5b), followed by adding titanium compound (A-4), titanium compound (A-4) and organic Any method of adding the metal compound (A-5b) at the same time is possible. First, the organometallic compound (A-5b) is added, and then the titanium compound (A-4) is added. Is preferred. The reaction between the titanium compound (A-4) and the organometallic compound (A-5b) is carried out in an inert hydrocarbon solvent, but it is preferable to use an aliphatic hydrocarbon solvent such as hexane or heptane. The catalyst thus obtained is used as a slurry solution using an inert hydrocarbon solvent.

  When the organometallic compound (A-5b) is used, before adding the titanium compound (A-4) and the organometallic compound (A-5b) to the solid (A-1c), the solid ( A-1c) is preferably reacted with alcohol in advance and further reacted with the organometallic compound (A-5b).

  Such alcohol is not particularly limited, but specifically, those having 1 to 10 carbon atoms are preferable. For example, methanol, ethanol, propanol, 2-propanol, 1-butanol, 2-butanol, 2- Examples include methyl-1-propanol, 1-methyl-2-propanol, 1-pentanol, 1-hexanol, 1-octanol, 2-ethyl-1-hexanol, and decanol. Among these, those having 2 to 6 carbon atoms are more preferable, for example, ethanol, propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-methyl-2-propanol, Examples thereof include 1-pentanol and 1-hexanol. Although it does not specifically limit about the usage-amount of alcohol, It is preferable that it is 0.01-1 with the molar ratio with respect to the magnesium atom contained in solid (A-1c), and it is still more preferable that it is 0.01-0.5. . The concentration of the alcohol at the time of use is not particularly limited, but it is preferably used after diluting to 0.1M to 2M using an inert hydrocarbon solvent. Although it does not specifically limit about the temperature of reaction with solid (A-1c) and alcohol, It is preferable that it is 25 to 150 degreeC, and it is more preferable that it is 40 to 80 degreeC.

  The reaction between the solid (A-1c) after the reaction with alcohol and the organometallic compound (A-5b) will be described. Although it does not specifically limit about the usage-amount of an organometallic compound (A-5b), It is preferable that it is 0.1-10 by molar ratio with respect to the used alcohol, and it is still more preferable that it is 0.5-5 times. Although there is no restriction | limiting in particular about the density | concentration at the time of use of an organometallic compound (A-5b), It is preferable that it is 0.1 mol / L-2 mol / L on the basis of M2 atom contained in an organometallic compound (A-5b). More preferably, it is 0.5 mol / L to 1.5 mol / L. In addition, it is preferable to use an inert hydrocarbon solvent for the dilution of the organometallic compound (A-5b). The temperature of the reaction between the solid (A-1c) after reacting with the alcohol and the organometallic compound (A-5b) is not particularly limited, but is preferably 25 ° C. to 150 ° C. or less, and 40 ° C. to 80 ° C. More preferably, the temperature is C.

  Next, the organometallic compound component [B] in the present embodiment will be described. The solid catalyst component [A] of the present embodiment becomes a highly active polymerization catalyst when combined with the organometallic compound component [B]. Although it does not specifically limit as organometallic compound component [B], Specifically, it is a compound containing the metal chosen from the group which consists of 1st group, 2nd group, 12th group, and 13th group of a periodic table. It is preferable that there is an organic aluminum compound and / or an organic magnesium compound.

As such an organoaluminum compound, a compound represented by the following formula (7) is preferably used alone or in combination.
AlR ¹⁷ _n Z _(3-n) (7)
(In the formula, R ¹⁷ is a hydrocarbon group having 1 to 20 carbon atoms, Z is a group selected from the group consisting of hydrogen, halogen, alkoxy, allyloxy and siloxy groups, and n is a number of 2 to 3).

In the above formula (7), the hydrocarbon group having 1 to 20 carbon atoms represented by R ¹⁷ is not particularly limited, and specifically, aliphatic hydrocarbon, aromatic hydrocarbon, alicyclic carbonization. The thing containing hydrogen is mentioned. The compound represented by the formula (7) is not particularly limited. For example, trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, tri (2-methylpropyl) aluminum, tripentylaluminum, tri ( Trimethylaluminum such as 3-methylbutyl) aluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum; diethylaluminum chloride, ethylaluminum dichloride, bis (2-methylpropyl) aluminum chloride, ethylaluminum sesquichloride, diethylaluminum bromide, etc. Aluminum halide compounds such as diethylaluminum ethoxide, bis (2-methylpropyl) aluminum butoxide, etc. Turkey alkoxy aluminum compounds; dimethylhydrosiloxy aluminum dimethyl, ethyl methyl hydro siloxy aluminum diethyl, siloxy aluminum compounds such as ethyl dimethylsiloxy aluminum diethyl; and mixtures thereof are preferred. Among these, a trialkylaluminum compound is more preferable.

The organomagnesium compound is preferably an organomagnesium compound that is soluble in the inert hydrocarbon solvent represented by the formula (8).
(M ¹ ) _a (Mg) _b (R ¹ ) _c (R ² ) _d (OR ³ ) _e Expression (8)
(In the formula, M ¹ is a metal atom other than magnesium selected from the group consisting of Group 1, Group 2, Group 12, and Group 13 of the Periodic Table, and R ¹ and R ² each have 2 to 2 carbon atoms. 20 is a hydrocarbon group, R ³ is a hydrocarbon group having 1 to 20 carbon atoms, and a, b, c, d, and e are real numbers that satisfy the following relationship: 0 ≦ a, 0 <b, 0 ≦ c, 0 ≦ d, 0 ≦ e, 0 <c + d, 0 ≦ e / (a + b) ≦ 2, f × a + 2b = c + d + e (where f is the valence of M ¹ ))

Such organomagnesium compounds are shown as complex forms of organomagnesium soluble in inert hydrocarbon solvents, but all of dialkylmagnesium compounds and complexes of this compound with other metal compounds. Is included. Since this organomagnesium compound is preferably a compound having high solubility in an inert hydrocarbon solvent, b / a is preferably 0.5 to 10, and more preferably a compound in which M ¹ is aluminum.

  The method for adding the solid catalyst component [A] and the organometallic compound component [B] into the polymerization system under the polymerization conditions is not particularly limited, and both may be added separately into the polymerization system. You may add in a polymerization system, after making both react. Moreover, although there is no restriction | limiting in particular in the ratio of both to combine, It is preferable that organometallic compound [B] is 1 mmol-3,000 mmol with respect to 1 g of solid catalyst components [A].

  The organoaluminum compound [B] used together with the solid catalyst component [A] of the present embodiment is not particularly limited. Specifically, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, tri trialkylaluminum such as iso-butylaluminum, tri-n-amylaluminum, triiso-amylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-n-decylaluminum; diethylaluminum chloride, ethylaluminum dichloride, diiso -Aluminum halides such as butyl aluminum chloride, ethyl aluminum sesquichloride, diethyl aluminum bromide; diethyl aluminum ethoxide, diiso-butyl alcohol Alkoxyaluminum such as minium butoxide; siloxyalkylaluminum such as dimethylhydrosiloxyaluminum dimethyl, ethylmethylhydrosiloxyaluminum diethyl, ethyldimethylsiloxyaluminum diethyl; and mixtures thereof are used, especially trialkylaluminum has achieved the highest activity. Therefore, it is preferable.

  The solid catalyst component [A] and the organoaluminum compound may be added to the polymerization system under the polymerization conditions, or may be mixed in advance prior to the polymerization. The ratio of both components to be combined is defined by the molar ratio of Ti in the solid catalyst component [A] and Al in the organoaluminum compound [B], and is preferably Al / Ti = 0.3 to 1000.

  As the polymerization solvent, a hydrocarbon solvent usually used for slurry polymerization is used. Specific examples include aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as benzene, toluene and xylene; and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. These hydrocarbon solvents may be used alone or in admixture of two or more. The polymerization temperature is usually in the range of room temperature to 100 ° C, preferably 50 ° C to 90 ° C. The polymerization pressure is usually carried out in the range of normal pressure to 100 atm. The molecular weight of the resulting polymer can be adjusted by allowing hydrogen to be present in the polymerization system or changing the polymerization temperature. Further, a method of producing by a vessel type slurry polymerization method using a supported geometrically constrained single site catalyst can also be preferably used.

  The polyethylene resin composition thus obtained is particularly preferable in that the high molecular weight polyethylene resin component can easily form a tie molecule because the amount of comonomer introduced into the high molecular weight polyethylene resin component can be increased.

(Other ingredients)
You may add an additive, a filler, etc. to the polyethylene resin composition used by the said this embodiment as needed. Although it does not specifically limit as an additive used, Specifically, various antioxidants, such as a phenolic antioxidant, phosphorus antioxidant, and sulfur type antioxidant; HALS type light stabilizer, benzophenone Various light stabilizers such as a light stabilizer and a benzotriazole ultraviolet absorber; neutralizers such as fatty acid metal salts and hydrotalcite; pigments and the like can be used. Further, the filler is not particularly limited, and specific examples include talc, silica, carbon, mica, calcium carbonate, magnesium carbonate, wood flour and the like. If necessary, it is possible to add titanium oxide or an organic pigment in a master batch.

[Use]
Piping materials (piping, joints, etc.) of the present embodiment contain the above polyethylene resin composition, are excellent in long-term creep characteristics, are classified into PE100 described in ISO 9080 standard, have a minimum guaranteed stress after 100 years, and are molded. Excellent workability. In addition, the piping material of the present embodiment is excellent in long-term characteristics, elongation characteristics, impact resistance, and moldability, and in addition, it tends to be excellent in surface properties such as SCG longevity enhancement and surface roughness characteristics.

  Here, “PE100” means that at least 9000 stress-fracture time curves were measured at three different temperatures in which the maximum temperature and the minimum temperature were separated by 50 ° C. or more in the hot internal pressure creep test described in ISO 9080. The LPL value of the value estimated by extrapolating the minimum guaranteed stress after 50 years at 20 ° C. by the multiple correlation average is 10 MPa or more and 11.19 MPa or less in the classification table defined in ISO12162, Polyethylene with a minimum guaranteed stress of 10 MPa. Specifically, it can be classified by the method described in the examples.

  “100 year warranty” refers to a polyethylene resin composition having a minimum guaranteed stress of 10 MPa or more by extrapolation after 100 years at 20 ° C. in the same manner as “PE100”. Specifically, it can be evaluated by the method described in Examples.

  The polyethylene resin composition used in the present embodiment is superior to the conventional resin composition for polyethylene piping materials in terms of longevity enhancement and surface properties of SCG, and the piping material obtained from this has dramatically improved long-term characteristics and production. The nature is also very high.

  Although it does not specifically limit as piping material, For example, a pipe or a coupling is mentioned, Preferably a pipe for water supply or a coupling for water supply is mentioned. In particular, when the piping material of the present embodiment is used as a pipe, it is excellent in long-term characteristics, rigidity, elongation characteristics, impact resistance, and molding processability under high temperature acceleration conditions, and in addition, it enhances the longevity and surface properties of SCG. Will also be an excellent pipe. In addition, when the piping material of this embodiment is used as a joint, it has excellent long-term characteristics under high temperature acceleration conditions, rigidity, elongation characteristics, impact resistance, and molding processability such as injection molding, and has excellent surface properties in injection molding. In addition to being excellent, the SCG has a long life.

  Taking water supply polyethylene pipes as an example of piping materials for waterworks, when tap water is used in Japan, the generation of bubbles due to chlorine water and the accompanying peeling of the surface layer occur. Chlorine water performance is required. Usually, when producing polyethylene pipes and joints, in order to limit the use as a pipe, it is usually provided in a colored form together with a coloring pigment. As described above, if the polyethylene pipe and the joint resin containing the color pigment contain a large amount of ash (component derived from the color pigment), it is considered that the chlorine resistance is lowered. Therefore, it is described in the polyethylene pipe for water supply of JIS K6762 that ash content is limited to a predetermined amount or less. The ash content in the pipe and the joint of the present embodiment is preferably 0.07% by mass or less, and more preferably 0.05% by mass or less.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples.

In the present invention and the following examples and comparative examples, the symbols and measurement methods shown are as follows.
(1) Melt flow rate, code D (MFR 2.16):
The melt index was expressed, and the low molecular weight polyethylene resin was measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kg according to JIS K7210. The unit was g / 10 min.

(2) Melt flow rate, code T (MFR5):
The melt index was expressed, and the polyethylene resin composition was measured according to JIS K7210 at a temperature of 190 ° C. and a load of 5.00 kg. The unit was g / 10 min.

(3) Density:
Low molecular weight polyethylene resin, high molecular weight polyethylene resin, and polyethylene resin composition were measured according to JIS K7112. The unit was kg / m ³ .

(4) Molecular weight distribution (Mw / Mn):
The polyethylene resin composition was measured by high temperature gel permeation chromatography (GPC), and obtained from the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the obtained molecular weight distribution chart. For the high-temperature GPC measurement, Waters Alliance GPCV2000 was used, and for the column, Showa Denko Co., Ltd. AT-807S (one) and Tosoh Corporation GMHHR-H (S) HT (two) were used. Connected in series, orthodichlorobenzene (ODCB) as mobile phase, column temperature 140 ° C., flow rate 1.0 mL / min, sample concentration 20 mg / solvent (ODCB) 10 mL, sample dissolution temperature 140 ° C., sample dissolution time 1 hour Went under.

(5) Flexural modulus The polyethylene resin composition was measured according to JIS K7171. The unit was MPa.

(6) Tensile elongation at break The polyethylene resin composition was measured according to JIS K7161. The unit is%.

(7) Charpy impact strength The polyethylene resin composition was measured according to JIS K7111. The unit is kJ / m ² .

(8) Hot internal pressure creep test (pipe hoop):
(8-1) Pipe forming Z
In the measurement of physical properties as a pipe, a pipe was molded using a polyethylene resin composition as follows and used for the test. The pipe uses an extruder with a diameter of 65 mm (manufactured by Toshiba Plastic Engineering Co., Ltd.). The resin composition is melted at 220 ° C., extruded into a cylindrical shape from a die with an outer diameter of 80 mm and an inner diameter of 68 mm attached to the extruder, and a sizing plate in a sizing tank The outer diameter is formed by passing through, and the sizing tank water temperature is cooled at 25 ° C. as primary cooling, and the pipe is cooled at 20 ° C. as secondary cooling in the next water tank after leaving the sizing tank. Was molded. The pipe was drawn with a take-up machine so that the outer diameter / thickness ratio = 11, and a tubular pipe having an outer diameter of 63 mm and a wall thickness of 5.8 mm was formed.

(8-2) PE class:
Three levels of temperatures of 20 ° C., 60 ° C., and 80 ° C. are selected according to the test method described in ISO 9080, and a hot internal pressure test is performed on the molded pipe with an arbitrary hoop stress. Measurement was performed so as to include at least one point of data after 9,000 hours. The logarithmic value of the test time and the logarithmic value of the hoop pressure were subjected to multiple correlation averaging at three temperatures, and the hoop pressure after 50 years was calculated by extrapolation for the lower confidence limit of 97.5% for the 20 ° C. line. Based on this, the PE class was determined from the range of σLCL corresponding to the minimum guaranteed stress according to the standard described in ISO12162.
Evaluation standard of PE class PE100: MRS = 10 MPa: 10 ≦ LCL ≦ 11.19
PE80: MRS = 80 MPa: 8 ≦ σLCL ≦ 9.99

(8-3) 100-year warranty (hoop pressure after 100 years):
Three levels of temperatures of 20 ° C., 60 ° C., and 80 ° C. are selected according to the test method described in ISO 9080, and a hot internal pressure test is performed on the molded pipe with an arbitrary hoop stress. Measurement was performed so as to include at least one point of data after 9,000 hours. Regarding the logarithmic value of the test time and the logarithm value of the hoop pressure, when there is no knee point, the model RI described in ISO / TR9080 is used, and when the knee point is present, the model RII is used, and a multiple correlation average is performed at three temperatures. The hoop pressure after 100 years was calculated by extrapolation for the lower confidence limit of 97.5% for the 20 ° C line. Based on this, the 100-year warranty was determined according to the following evaluation criteria.
Evaluation criteria for 100-year warranty ○: Estimated value after 100 years is 10 MPa or more ×: Less than 10 MPa

(8-4) Calculation of slope ratio:
The ratio of the slope is obtained by performing linear regression using a linear model with a least squares method for the slope of the plot line of less than 1,000 hours and the slope of the plot line after 1,000 hours in the hot internal pressure test at 20 ° C. It was. Using this, the ratio of the slope of the plot line of less than 1,000 hours to the slope after 1,000 hours (the slope of less than 1,000 hours / the slope after 1,000 hours) was determined.

(8-5) Knee Point judgment:
Based on ISO 9080, Knee Point conducts a hot internal pressure test at 80 ° C. using a pipe without a notch, and changes from ductile fracture on the low time side to brittle fracture on the high time side when expressing the hoop stress with respect to the elapsed time ( Knee) was evaluated according to the following evaluation criteria.
“Yes”: Change (Knee) appears “None”: No change (Knee), only ductile fracture

(9) SCG test Using the method described in ISO 13479, the notch depth is 0.18 to 0.22 times the thickness of the pipe obtained in (8-1) above, and the length is the pipe outer diameter. Four notches were put in the pipe under the same length as above, a notch tip R of 0.05 to 0.10 mm, and a blade moving speed of 72 cm / min.

  Then, the hot internal pressure test was done at 80 degreeC using the pipe which put the notch based on ISO9080. When a change (Knee) appeared from a ductile fracture on the low time side to a brittle fracture on the high time side when the hoop pressure was expressed with respect to the elapsed time, the time was defined as SCG (hr).

(10) CFC volume fraction (temperature elution fractionation GPC cross fractionation):
The fraction (R, unit: wt%) of the total elution amount of elution components with a molecular weight of 200,000 or more and an elution temperature of 85 ° C or less to the total integrated elution amount, cross-separation between temperature rising elution fractionation and gel permeation chromatography The molecular weight, elution temperature, and elution amount obtained by The cumulative elution amount of elution components having a molecular weight of 200,000 or more and an elution temperature of 85 ° C. or less corresponds to the hatched portion in FIG. The ratio to the total accumulated elution amount is R. As a measuring device, a CFC manufactured by Polymer char was used. As a column for gel permeation chromatography, AT-807S (1) manufactured by Showa Denko KK and GMHHR-H (S) HT (2) manufactured by Tosoh Co., Ltd. are connected in series, and the mobile phase is ortho. Using dichlorobenzene (ODCB), the column temperature was 140 ° C., the flow rate was 1.0 mL / min, the sample concentration was 20 mg / solvent (ODCB) 10 mL, the sample dissolution temperature was 140 ° C. .

  The sample concentration was 0.1 to 0.3 wt / vol%, the injection amount was 0.5 mL, and the flow rate was 1.0 mL / min. The sample was heated at 140 ° C. for 2 hours, then cooled to 20 ° C. at 10 ° C./hr, and further held at 20 ° C. for 60 minutes to coat the sample. An infrared spectrometer was used as a detector, and infrared light of 3.42 μm was detected. The elution temperature was 40 ° C. to 140 ° C., and it was divided into 1 ° C. fractions in the vicinity of the elution peak. The molecular weight of the eluted fraction at each temperature was measured. Next, an elution amount having a molecular weight of 200,000 or more and an elution temperature of 85 ° C. or less was calculated from the integrated value for each molecular weight of each fraction, and the total amount ratio was taken as R.

(11) Pipe surface property When the surface of the pipe obtained in (8-1) above is visually confirmed, x is observed when stripes due to melt fracture or irregularities due to roughness are observed, and Δ when slightly rough skin is caused. When it was smooth, it was marked as “◯”.

[Example 1]
[Preparation of catalyst]
(Preparation of solid catalyst component [A])
(1) Synthesis of magnesium-containing solid by reaction with chlorosilane compound 2740 mL of trichlorosilane (HSiCl ₃ ) (component (ii)) as a 2 mol / L n-heptane solution was charged into a fully nitrogen-substituted 15 L reactor. , stirring while keeping the 65 ° C., this organomagnesium component represented by the formula _{AlMg 6 (C 2 H 5)} 3 (i-C 4 H 9) 10.8 (Oi-C 4 H 9) 1.2 7L (5 mol in terms of magnesium) of n-heptane solution of (component (i)) was added over 1 hour, and the mixture was further reacted with stirring at 65 ° C. for 1 hour. After completion of the reaction, the supernatant was removed and washed 4 times with 7 L of n-hexane to obtain a solid slurry. As a result of separating and drying this solid (A-1a) and analyzing it, it contained Mg 8.62 mmol, Cl 17.1 mmol and i-butoxy group (Oi-C ₄ H ₉ ) 0.84 mmol per 1 g of the solid.

(2) Preparation of Solid Catalyst A slurry containing 500 g of the above solid (A-1a) was stirred at 50 ° C. with 2,160 mL of a 1 mol / L n-hexane solution of iso-butyl alcohol (component (A-2)). For 1 hour. After completion of the reaction, the supernatant was removed and washed once with 7 L of n-hexane to obtain a solid slurry (A-1b). This solid slurry (A-1b) was kept at 50 ° C., and 970 mL of 1 mol / L n-hexane solution of diethylaluminum chloride (component (A-3)) was added with stirring to react for 1 hour. After completion of the reaction, the supernatant was removed and washed twice with 7 L of n-hexane to obtain a solid slurry (A-1c). The solid slurry (A-1c) was kept at 50 ° C., and 270 mL of n-hexane solution of 1 mol / L of diethylaluminum chloride and 270 mL of n-hexane solution of 1 mol / L of titanium tetrachloride (component (A-4)) were added. Reacted for 2 hours. After completion of the reaction, the supernatant was removed and washed with 7 L of n-hexane four times while maintaining the internal temperature at 50 ° C. to obtain a solid catalyst component (component [A]) as a hexane slurry solution. The chlorine ion concentration in the supernatant of the solid catalyst slurry solution was 2.5 mmol / L, and the aluminum ion concentration was 4.5 mmol / L.

(3) Polymerization Two-stage polymerization by two polymerization tanks connected in series by a continuous slurry polymerization method using a polymerization catalyst containing the solid catalyst component [A] obtained above and triethylaluminum (component [B]). Went. The comonomer used was 1-butene. The first stage polymerization tank is supplied with only ethylene as a monomer and polymerized at a temperature of 85 ° C., a pressure of 7.2 Kg / cm ³ G, and a hydrogen concentration of 48%, and the second stage contains ethylene and 1-butene. The polymerization was conducted at 70 ° C., 2.6 kg / cm ³ G, hydrogen concentration 1.2%, and 1-butene concentration 7.5%. The production ratio of the low molecular weight polyethylene resin component (A) made of an ethylene homopolymer obtained in the first stage polymerization tank is 55 wt%, and the high molecular weight polyethylene resin component made of a copolymer obtained in the second stage polymerization tank. The ratio of the production amount of (B) was set to 45 wt%, and a powder having an MFR5 of 0.71 g / 10 minutes and a density of 950 kg / m ³ was obtained.

The powder obtained by the above polymerization was dried, and 1,000 ppm of tri (2,4-di-t-butylphenyl) phosphate as a secondary antioxidant and tetrakis as a heat stabilizer for 100 parts by mass of the powder. (3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate) 1,500 ppm of methane, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) as weathering agent ) Extrusion at 400 ppm of 5-chlorobenzotriazole, 300 ppm of calcium stearate, Nippon Steel's TEX-44 type extruder (screw diameter 44 mm, L / D = 42) at a set temperature of 200 ° C. and a resin extrusion rate of 40 kg / hr Pellet was obtained by granulating. The pellet had an MFR5 of 0.25 g / 10 min and a density of 950 kg / m ³ . A test piece was prepared using this pellet, and physical properties were measured.

  Further, a pipe having an outer diameter of 63 mm was formed using the pellet, and the physical properties of the pipe were measured. The results are shown in Table 1. The relationship between time and hoop pressure is shown in FIG. In FIG. 2, plots of less than 1,000 hours are indicated by ♦, plots after 1,000 hours are indicated by □, and each plot is calculated by regression using a least square method of a linear equation, and the plot lines are represented by straight lines. Indicated.

  The relationship between the fracture time and the hoop pressure in the SCG test is indicated by □ in FIG. When ductile fracture occurred on the short time side and brittle fracture occurred on the long time side, the knee point at the displacement point was calculated to be 1,007 hours, which was a sufficiently long time. Furthermore, when the surface property of the pipe was visually confirmed, the inner surface of the pipe was slightly roughened.

[Example 2]
The first stage polymerization tank is polymerized at a pressure of 5.5 kg / cm ³ G and a hydrogen concentration of 38%, and the second stage is a pressure of 2.3 kg / cm ³ G, a hydrogen concentration of 0.8%, and 1-butene. Polymerization at a concentration of 7.7%, the proportion of the production amount of the low molecular weight component (A) consisting of an ethylene homopolymer obtained in the first stage polymerization tank is 58 wt%, the co-polymer obtained in the second stage polymerization tank except for setting the proportion of the production of high molecular weight component comprising polymer (B) to 42 wt% is in the same manner as in example 1, MFR5 is 0.90 g / 10 min and a density of 950 kg / ^{m 3} powder, and MFR5 is Pellets with a density of 0.27 g / 10 min and a density of 950 kg / m ³ were obtained. Further, a pipe having an outer diameter of 63 mm was formed using the pellet, and the physical properties of the pipe were measured. The results are shown in Table 1. The relationship between time and hoop pressure is shown in FIG. In FIG. 3, plots of less than 1,000 hours are indicated by ◆, plots after 1,000 hours are indicated by □, and each plot is calculated by regression using a least square method of a linear expression, and the plot lines are represented by straight lines. Indicated.

  The relationship between the breaking time and the hoop pressure in the SCG test is shown by ◇ in FIG. When ductile fracture occurred on the short time side and brittle fracture occurred on the long time side, the Knee point at the displacement point was calculated to be 679 hours. Furthermore, when the surface property of the pipe was visually confirmed, it was smooth with no rough skin.

[Comparative Example 1]
The first stage polymerization tank is polymerized at a pressure of 7.2 Kg / cm ³ G and a hydrogen concentration of 48%, and the second stage is a pressure of 2.3 Kg / cm ³ G, a hydrogen concentration of 1.5%, and 1-butene. Polymerization at a concentration of 9.0%, the proportion of the production amount of the low molecular weight component (A) consisting of an ethylene homopolymer obtained in the first stage polymerization tank is 55 wt%, the co-polymer obtained in the second stage polymerization tank A powdered polyethylene having an MFR5 of 0.78 g / 10 min and a density of 948 kg / m ^{3 in} the same manner as in Example 1 except that the production rate of the high molecular weight component (B) made of coalescence was set to 45 wt%. A resin was obtained. Thereafter, extrusion was performed in the same manner as in Example 1 to obtain pellets having an MFR5 of 0.33 g / 10 minutes and a density of 948 kg / m ³ . Evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1. FIG. 4 shows the relationship between time and hoop pressure. In FIG. 4, plots of less than 1,000 hours are indicated by ♦, plots after 1,000 hours are indicated by □, and each plot line is indicated by a straight line.

  The relationship between the breaking time and the hoop pressure in the SCG test is indicated by ◯ in FIG. It was 813 hours when ductile fracture occurred on the short time side and brittle fracture occurred on the long time side, and the Knee point of the displacement point was calculated. Furthermore, when the surface property of the pipe was visually confirmed, the inner surface of the pipe was severely rough.

[Comparative Example 2]
A stainless steel autoclave with an internal volume of 20 L that has been sufficiently purged with nitrogen is charged with 4 L of a 1 mol / L hydroxytrichlorosilane hexane solution and stirred at 50 ° C., and the composition formula AlMg ₅ (C ₄ H ₉ ) ₁₁ (OC ₂ H ₅ ) A hexane solution 9L (corresponding to 6.5 mol of magnesium) of the organomagnesium compound represented by ₂ was added dropwise over 4 h, and the reaction was further continued at 50 ° C. for 1 h with stirring. After completion of the reaction, the supernatant was removed and washed 4 times with 7 L of hexane to obtain a carrier. As a result of analyzing this carrier, the amount of magnesium contained in 1 g of the carrier was 8.44 mmol.

  While stirring at 50 ° C., 450 mL of a 1 mol / L 1-propanol hexane solution was added to 13 L of hexane slurry containing 500 g of the carrier over 30 minutes. After the addition, the reaction was continued at 50 ° C. for 1 hour. After completion of the reaction, 7 L of the supernatant was removed, 6.4 L of hexane was added, the temperature was set to 65 ° C., and 600 mL of a 1 mol / L diethylaluminum chloride hexane solution was added over 1 hour 30 minutes. After the addition, the reaction was continued at 65 ° C. for 1 hour. After completion of the reaction, 7 L of the supernatant was removed and washed 4 times with 7 L of hexane to obtain a slurry. Remove 600 mL of the supernatant of the slurry after washing, add 265 mL of a 1 mol / L diethylaluminum chloride hexane solution over 5 minutes while stirring at 50 ° C., and subsequently add 265 mL of a 1 mol / L titanium tetrachloride hexane solution for 5 minutes. Added over time. After the addition, the reaction was continued at 50 ° C. for 2 hours. After completion of the reaction, 7 L of the supernatant was removed, and the solid catalyst component was prepared by washing 4 times with 7 L of hexane. The amount of titanium contained in 1 g of this solid catalyst component was 0.52 mmol.

  First, in the first stage polymerization, a stainless polymerizer 1 having a reaction volume of 300 L was used to produce a low molecular weight component. The sum of the volume of the solvent in the polymerization vessel and the volume of the polyolefin measured by a liquid level meter using γ rays is 170 L, and the rate per volume at which the solvent and the polyolefin are regularly extracted from the polymerization vessel is 51 L. / H. Therefore, the average residence time in the first stage was 3.3 hours. Low molecular weight components were withdrawn from the polymerization vessel 1 at a rate of 10 kg / h. Under the conditions of a polymerization temperature of 85 ° C. and a polymerization pressure of 1 MPa, the above solid catalyst was introduced as a catalyst at 0.5 mmol / h in terms of Ti atoms, and the above organoaluminum compound was introduced at 20 mmol / h in terms of Al atoms, Hexane was introduced at a rate of 40 L / h. Hydrogen is used as the molecular weight regulator, and is supplied so that the gas phase molar concentration (hydrogen / (ethylene + hydrogen)) of the sum of ethylene and hydrogen is 65 mol%, and the supply amount of ethylene is 10 kg / h. Then, the polymerization was carried out by supplying the polymerization vessel.

The polymerization activity in the polymerization vessel 1 was 3,200 g / g / h. The melt flow rate (MFR 2.16) of the low molecular weight component produced in Polymerizer 1 was 160 g / 10 min, and the density was 972 kg / m ³ .

  In order to remove hydrogen in the polymer slurry, the polymer slurry solution in the polymerization vessel 1 was led to a flash drum having a pressure of 0.1 MPa and a temperature of 75 ° C. at a rate of 51 L / h to separate unreacted ethylene and hydrogen.

  Next, in order to produce a high molecular weight component in the second-stage polymerization, a stainless polymerizer 2 having a reaction volume of 300 L is used, and the polymer slurry solution is 51 L / h and hexane 95 L / h, and the combined speed is 146 L / h. Was introduced into the polymerization vessel 2. The organoaluminum compound was introduced at 47 mmol / h in terms of Al atoms. The sum of the volume of the solvent in the polymerization vessel and the volume of the copolymer of ethylene and α-olefin measured by a liquid level meter using γ-ray is 146 L, and the solvent, ethylene and α-olefin are removed from the polymerization vessel. The volume per volume at which the copolymer was extracted constantly was 157 L / h. Therefore, the average residence time in the first stage was 0.90 hours. From the polymerization vessel 2, a polyethylene composition comprising a low molecular weight component and a high molecular weight component was withdrawn at a rate of 20 kg / h.

  In the polymerization vessel 2, the organoaluminum compound was introduced at a rate of 47.5 mmol / hr in terms of Al atoms under the conditions of a temperature of 70 ° C. and a pressure of 0.2 MPa. To this, ethylene, hydrogen, 1-butene, total pressure 0.2 MPa, hydrogen gas phase concentration 1.3 mol%, 1-butene gas phase concentration 4.3 mol%, ethylene supply amount and 1-butene The weight ratio of the low molecular weight portion produced in the polymerization vessel 1 to the high molecular weight portion produced in the polymerization vessel 2 (high molecular weight portion) / The high molecular weight portion was polymerized so that (low molecular weight portion) was 45/55.

MFR5 is 0.88 g / 10 min at powder form, density to produce a powdered polyethylene resin composition is 950 kg / ^{m 3.}

Thereafter, extrusion was performed in the same manner as in Example 1 to obtain pellets having an MFR5 of 0.37 g / 10 min and a density of 950 kg / m ³ . Evaluation was performed in the same manner as in Example 1, and the results are shown in Table 1. FIG. 5 shows the relationship between time and hoop pressure. In FIG. 5, a plot of less than 1,000 hours is indicated by ♦, a plot after 1,000 hours is indicated by □, and each plot line is indicated by a straight line.

  The relationship between the breaking time and the hoop pressure in the SCG test is indicated by Δ in FIG. When ductile fracture occurred on the short time side and brittle fracture occurred on the long time side, and the Knee point at the displacement point was calculated, it was as short as 224 hours. Furthermore, when the surface property of the pipe was visually confirmed, it was smooth with no rough skin.

[Comparative Example 3]
The melt flow rate (MFR 2.16) of the low molecular weight component produced in the polymerization vessel 1 is 200 g / 10 min. The weight ratio of the low molecular weight portion produced in the polymerization vessel 1 to the high molecular weight portion produced in the polymerization vessel 2 (high Comparative Example 2 except that a powdered polyethylene having a molecular weight part) / (low molecular weight part) of 50/50, MFR5 in powder form of 0.44 g / 10 min, and density of 952 kg / m ³ was produced. Pellets having an MFR5 of 0.22 g / 10 min and a density of 952 kg / m ³ were obtained. Except for the SCG test, evaluation was performed in the same manner as in Example 1, and the measurement results are shown in Table 1. The relationship between time and hoop pressure is shown in FIG. In FIG. 6, a plot of less than 1,000 hours is indicated by ♦, a plot after 1,000 hours is indicated by □, and each plot line is indicated by a straight line. Furthermore, when the surface property of the pipe was visually confirmed, the inner surface of the pipe was severely rough.

  As described above, it has been shown that the piping material of the present invention is excellent in SCG longevity enhancement and surface properties by having a specific density, MFR5, molecular weight distribution, and creep curve slope ratio.

  Piping material containing the polyethylene resin composition of the present invention is excellent in physical properties, especially long-term characteristics, moldability, surface properties when used as pipes and joints, pipes and joints of waterworks, sewerage, agricultural pipes and various transportation pipes, etc. It is most suitable as a material.

Claims (8)

A piping material containing an ethylene homopolymer and / or a polyethylene resin composition that includes a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms and satisfies the following (1) to (4).
(1) The density is 948 to 952 kg / m ³ .
(2) The melt flow rate (code T) is 0.15 g / 10 min or more and less than 0.30 g / 10 min.
(3) The molecular weight distribution is 15 or more and less than 25.
(4) In the hot internal pressure creep test at 20 ° C. specified by ISO 9080, the ratio of the slope of the plot line of the logarithm of the hoop pressure to the logarithm of the fracture time has the following relationship.
Slope less than 1,000 hours / Slope after 1,000 hours> 1.5 The polyethylene resin composition is
An ethylene homopolymer and / or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a density of 967 to 973 kg / m ³ , and a melt flow rate (Code D) of 40 to 60 g / Polyethylene resin (I) 55-60 parts by mass,
A polyethylene resin (II) which is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, a density of 920 to 930 kg / m ³ , and a weight average molecular weight of 500,000 to 1,000,000. The piping material according to claim 1, comprising 40 to 45 parts by mass.   The polyethylene resin composition produces an ethylene homopolymer in the first stage polymerization tank, and produces a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms in the second stage polymerization tank. The piping material according to claim 1 or 2, which is obtained by a polymerization method. The ethylene homopolymer and / or the copolymer is composed of 1 mol of an organomagnesium compound (i) soluble in a hydrocarbon solvent represented by the following formula (1) and a chlorosilane compound (ii) represented by the following formula (2): ) 0.01-100 mol is reacted to obtain a solid (A-1a),
0.01-1 mol of alcohol (A-2) is reacted with 1 mol of C—Mg bond contained in the solid (A-1a) to obtain a solid (A-1b),
The solid (A-1b) is reacted with an organometallic compound (A-3) represented by the following formula (3) to obtain a solid (A-1c).
The solid (A-1c) is obtained by using the polymerization catalyst containing the solid catalyst component [A] and the organoaluminum compound [B] obtained by supporting the titanium compound (A-4) on the solid (A-1c). The piping material according to any one of claims 1 to 3.
(Al) _a (Mg) _b (R ¹ ) _c (R ² ) _d (OR ³ ) _e Formula (1)
(In the formula (1), R ¹ , R ² and R ³ are hydrocarbon groups having 2 to 20 carbon atoms, and a, b, c, d and e are numbers satisfying the following relationship: 0 ≦ a , 0 <b, 0 ≦ c, 0 ≦ d, 0 ≦ e, 0 <c + d, 0 ≦ e / (a + b) ≦ 2, 3a + 2b = c + d + e)
H _h SiCl _i R ⁴ _{4- (h + i)} (2)
(In Formula (2), R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms, and h and i are numbers satisfying the following relationship: 0 <h, 0 <i, h + i ≦ 4)
AlR ⁵ _s Q _3-s (3)
(In formula (3), R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms, and Q is selected from the group consisting of OR ⁶ , OSiR ⁷ R ⁸ R ⁹ , NR ¹⁰ R ¹¹ , SR ¹² and halogen. R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² are hydrogen atoms or hydrocarbon groups, and s is a number that satisfies the following relationship: 0 <s <3 )   The piping material according to any one of claims 1 to 4, which is a pipe.   The piping material according to any one of claims 1 to 4, which is a joint.   The piping material according to claim 5, wherein the pipe is for water supply.   The piping material according to claim 6, wherein the joint is for water supply.