JP2017128658A - ETHYLENE-α-OLEFIN COPOLYMER - Google Patents

Abstract

An ethylene-α-olefin copolymer capable of producing a silane-crosslinked polyethylene having a high crosslinking rate and a high gel fraction, a method for producing the same, and a resin containing the ethylene-α-olefin copolymer It aims at providing the resin composition containing the composition and its manufacturing method, the obtained silane graft modified polyethylene, and a silane crosslinked polyethylene pipe.
A copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms, having a melt flow rate at 190 ° C. and 2.16 kg of 1.0 g / 10 min to 10 g / 10 min. The peak top time (1/2 isothermal crystallization time) in isothermal crystallization at + 5 ° C. with respect to the crystallization start temperature (Cp Onset) determined by the differential scanning calorimeter (DSC) method is 300 An ethylene-α-olefin copolymer, which is at least 2 seconds.
[Selection figure] None

Description

  The present invention relates to an ethylene-α-olefin copolymer and a production method thereof, a resin composition containing the ethylene-α-olefin copolymer and a production method thereof, a silane graft-modified polyethylene resin composition, and a silane-crosslinked polyethylene pipe.

  In recent years, plastics superior in corrosion resistance and workability compared to conventional metal materials have been used as piping materials. Among these, silane-crosslinked polyethylene, which is particularly excellent in pressure resistance and creep resistance in a high temperature region, is often used. Such silane-crosslinked polyethylene is widely used, for example, in the fields of hot water supply, water supply, floor heating, and load heating, power cable insulation layers, and shrinkable tubes. Among these fields, in particular, silane-crosslinked polyethylene used for pipes for hot water supply, water supply, floor heating, and road heating requires flexibility from the viewpoint of workability during piping. .

  Silane-crosslinked polyethylene is produced, for example, by the following method. First, an organic unsaturated silane compound is grafted onto polyethylene using a radical generator (hereinafter also referred to as “silane graft modification”) to produce a silane graft modified polyethylene. Next, the silane-grafted modified polyethylene is crosslinked in the presence of a silanol condensation catalyst and moisture (hereinafter also referred to as “silane crosslinking”) to obtain a silane-crosslinked polyethylene.

  In the actual manufacturing process, a silane-crosslinking reaction is caused by bringing a pipe obtained by extruding silane graft-modified polyethylene into contact with hot water at 80 ° C. or higher for a certain time (for example, 10 hours or longer). The crosslinking process becomes a bottleneck. In addition, the silane-crosslinked polyethylene pipe standard (JIS K6769) stipulates that it is 65% or more in the gel fraction measurement in which the residual amount is extracted in a xylene bath and the remaining amount is measured. There has been a demand for a raw material or a production method in which the fraction is increased, that is, the crosslinking rate is high, and the final gel fraction is high, that is, the crosslinking efficiency is increased. (Patent Documents 1 to 3)

JP 7-330979 A Japanese Patent Laid-Open No. 3-31730 JP 2009-120646 A

  However, with the technique disclosed in Patent Document 1, the crosslinking rate is not improved and the gel fraction is not sufficient. In the technique disclosed in Patent Document 2, the crosslinking rate and the gel fraction are improved as compared with Patent Document 1, but it is not sufficient. Furthermore, in the technique disclosed in Patent Document 3, the gel fraction after the cross-linking reaction at 95 ° C. for 24 hours is greatly improved to 75% by using a specific polyethylene, but the cross-linking rate is mentioned. It has not been.

  The present invention has been made in view of the above problems, and provides an ethylene-α-olefin copolymer capable of producing a silane-crosslinked polyethylene having a high crosslinking rate and a high gel fraction. Objective.

  As a result of diligent research to solve the above-described problems of the prior art, the inventors of the present invention are a copolymer of ethylene and an α-olefin having a predetermined number of carbon atoms, and a melt flow rate in a predetermined range. The present invention has found that an ethylene-α-olefin copolymer having a ½ isothermal crystallization time can produce a silane-crosslinked polyethylene having a high crosslinking rate and a high gel fraction. It came.

That is, the present invention is as follows.
[1]
A copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms,
The melt flow rate at 190 ° C. and 2.16 kg is 1.0 g / 10 min or more and 10 g / 10 min or less,
The peak top time (1/2 isothermal crystallization time) in isothermal crystallization at + 5 ° C. is 300 seconds or more with respect to the crystallization start temperature (Cp Onset) determined by the differential scanning calorimeter (DSC) method. is there,
Ethylene-α-olefin copolymer.
[2]
Density is 930 kg / m ³ or more 950 kg / m ³ or less,
The ethylene-α-olefin copolymer according to [1].
[3]
The molecular weight distribution based on the weight average molecular weight and the number average molecular weight determined from gel permeation chromatography is 2.5 or more and 5.0 or less,
The short chain branching distribution obtained from gel permeation chromatography and FT-IR and represented by the following formula (A) is 0.1 or more and 2.0 or less.
The ethylene-α-olefin copolymer according to [1] or [2].
Short chain branch distribution = (number of short chain branches per 1000 carbons when log M is 5.0) − (number of short chain branches per 1000 carbons when log M is 4.0) (A)
(In formula (A), M represents the molecular weight in gel permeation chromatography, and log M represents the logarithm of M with 10 as the base.)
[4]
Including the ethylene-α-olefin copolymer according to any one of [1] to [3] and an antioxidant;
The content of the substance functioning as the antioxidant is 200 mass ppm or less,
Resin composition.
[5]
The ethylene-α-olefin copolymer according to any one of [1] to [3] is continuously passed through an extruder at least twice, kneaded and granulated to obtain the resin composition according to [4]. Having a granulation step to obtain,
A method for producing a resin composition.
[6]
The relationship between the resin temperature T1 in the first stage extruder and the resin temperature T2 in the second stage extruder is T1 <T2.
[5] The method for producing a resin composition according to [5].
[7]
In the presence of a supported geometrically constrained metallocene catalyst, ethylene is copolymerized with an α-olefin having 3 to 8 carbon atoms, and ethylene-α according to any one of [1] to [3] -Having a polymerization step to obtain an olefin copolymer;
A method for producing an ethylene-α-olefin copolymer.
[8]
The ethylene-α-olefin copolymer according to any one of [1] to [3] and 0.025 parts by mass or more and 1.0 parts by mass with respect to 100 parts by mass of the ethylene-α-olefin copolymer. Containing an organic peroxide of not more than part by mass and an organic unsaturated silane compound of not less than 0.1 parts by mass and not more than 1.5 parts by mass,
Silane graft-modified polyethylene resin composition.
[9]
Including the crosslinked product of the silane graft-modified polyethylene resin composition according to [8],
Silane cross-linked polyethylene pipe.

  According to the present invention, an ethylene-α-olefin copolymer capable of providing a silane-grafted modified polyethylene having a high crosslinking rate, and capable of producing a silane-crosslinked polyethylene pipe having a high gel fraction. -An olefin copolymer and a method for producing the same can be provided. Moreover, the resin composition containing this ethylene-alpha-olefin copolymer, its manufacturing method, the silane graft modified polyethylene resin composition, its manufacturing method, and a silane crosslinked polyethylene pipe can be provided.

In Example 1 and Comparative Example 8, it is the figure which calculated | required distribution of molecular weight and the number of short chain branches.

  Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to this embodiment, It can implement in various deformation | transformation within the range of the summary.

[Ethylene-α-olefin copolymer]
The ethylene-α-olefin copolymer of the present embodiment is a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms, and has a melt flow rate of 1.0 g at 190 ° C. and 2.16 kg. / 10 min or more and 10 g / 10 min or less, and the peak top time (1/2 isothermal crystal in isothermal crystallization at + 5 ° C.) with respect to the crystallization start temperature (CpOnset) determined by the differential scanning calorimeter (DSC) method ) Is 300 seconds or more.

  By having the above-described configuration, the ethylene-α-olefin copolymer can produce a silane-crosslinked polyethylene pipe having a high crosslinking rate and a high gel fraction. Hereafter, each said requirement is demonstrated in detail.

The ethylene-α-olefin copolymer is a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms (hereinafter also simply referred to as “comonomer”). Although the comonomer which can be used by this embodiment is not specifically limited, For example, the alpha-olefin of a following formula is mentioned.
H ₂ C═CHR ²
(In the formula, R ² represents a linear or branched alkyl group having 1 to 6 carbon atoms.)

  Specific comonomers include, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Among these, propylene and 1-butene are preferable from the viewpoint of economy and ease of handling. Further, by using an α-olefin having 8 or less carbon atoms, the number of tertiary carbon atoms per 1000 carbon atoms is not relatively decreased.

  The molar ratio of ethylene in the ethylene-α-olefin copolymer is preferably 80% or more and less than 100%, more preferably 85%, from the viewpoint of adjusting density, short chain branching distribution, and MFR. It is 99% or less and more preferably 90% or more and 98% or less.

The ethylene-α-olefin copolymer preferably has substantially no long chain branching. Since the ethylene-α-olefin copolymer having substantially no long chain branching also has less tertiary carbon contained in the long chain branching, grafting of an organic unsaturated silane compound with an organic peroxide described later In the modification reaction, the radical concentration in the ethylene-α-olefin copolymer is suppressed, side reactions such as decomposition reaction and cross-linking reaction between the ethylene-α-olefin copolymers are suppressed, and the silane graft modification efficiency Tend to be hard to fall. Here, “substantially no long chain branching” means that long chain branching cannot be confirmed in the ethylene-α-olefin copolymer by a known ¹³ C-nuclear magnetic resonance method. means. More specifically, in the ¹³ C-nuclear magnetic resonance method, those having 6 or less branched carbon atoms are referred to as “short chains”, and those having more than 6 branched carbon atoms are referred to as “long chains”. As a method for obtaining an ethylene-α-olefin copolymer having substantially no long chain branching, a general Ziegler-Natta catalyst or a supported metallocene catalyst described later can be used.

  The ethylene-α-olefin copolymer in this embodiment has a melt flow rate of 190 ° C. and 2.16 kg (hereinafter also simply referred to as “MFR”) of 1 g / 10 min to 10 g / 10 min, preferably 2 g. / 10 min or more and 8 g / 10 min or less, more preferably 2.5 g / 10 min or more and 7 g / 10 min or less. If the ethylene-α-olefin copolymer is 190 ° C. and the melt flow rate of 2.16 kg is 1 g / 10 min or more, melt fracture is unlikely to occur and the appearance of the silane-crosslinked polyethylene pipe is not impaired. It is also excellent in extrusion processability. Furthermore, the resin pressure and the share at the time of melt molding can be reduced. On the other hand, if the ethylene-α-olefin copolymer is 190 ° C. and the melt flow rate of 2.16 kg is 10 g / 10 min or less, the mechanical strength and flexibility of the silane-crosslinked polyethylene pipe are improved.

  Although the melt flow rate in 190 degreeC and 2.16 kg of an ethylene-alpha-olefin copolymer is not specifically limited, For example, it can mainly adjust with the molecular weight of a copolymer. The molecular weight can be adjusted by the presence of hydrogen during the polymerization. The melt flow rate at 190 ° C. and 2.16 kg of the ethylene-α-olefin copolymer is measured by the method described in Examples described later.

  The peak top time (1/2 isothermal) in isothermal crystallization at + 5 ° C. with respect to the crystallization start temperature (Cp Onset) determined by the differential scanning calorimeter (DSC) method of the ethylene-α-olefin copolymer. The crystallization time) is 300 seconds or longer, preferably 350 seconds or longer, more preferably 400 seconds or longer. The upper limit of the peak top time (1/2 isothermal crystallization time) is not particularly limited, but is preferably 1000 or less.

  The 1/2 isothermal crystallization time substantially represents the crystallization rate, and the shorter the 1/2 isothermal crystallization time, the faster the crystallization rate of the ethylene-α-olefin copolymer at a predetermined temperature. Show. In conventional polyethylene molding, it has been considered that the use of a raw material having a high crystallization speed contributes to an improvement in the speed of a series of molding cycles from molding to cooling and solidification, that is, an improvement in productivity. However, as a result of the study by the present inventors, in the silane-crosslinked polyethylene pipe, the conventional raw material having a high crystallization rate is inferior to the cross-linking rate of the silane cross-linking. It became clear that it would be faster. The reason for this is not necessarily clear, but with a raw material with a high crystallization rate, the silane graft-modified part (alkoxysilane) in the polymer chain is constrained in a separated state because it solidifies instantaneously upon cooling after molding. Conceivable. Therefore, it is thought that the site | part used as a crosslinking point becomes far, and as a result, the crosslinking rate of silane crosslinking becomes slow. On the other hand, since raw materials with a low crystallization rate have a certain amount of time for cooling and solidification after molding, there is an opportunity for the silane graft modified portion (alkoxysilane) in the polymer chain to approach due to chemical interaction such as hydrogen bonding. It is thought to increase. Therefore, it is considered that the site to be a cross-linking point is close and the cross-linking rate of silane cross-linking is increased.

  When using a raw material having a high crystallization rate, that is, a slow silane crosslinking rate, the distance between crosslinking points is reduced in order to increase the crosslinking rate, that is, a large amount of organic unsaturated silane compound is used during silane graft modification. It is necessary to increase the number of graft modification sites that become crosslinking points. However, the cost of expensive silane compounds is high, and odors peculiar to silane compounds are generated at the time of production. Therefore, such a method is not preferable economically and in working environment.

  The 1/2 isothermal crystallization time of the ethylene-α-olefin copolymer is not particularly limited, but can be controlled by appropriately adjusting the granulation conditions and the like. Specifically, (1) the ethylene-α-olefin copolymer is continuously passed through a twin-screw extruder at least twice, (2) temperature conditions of the first stage extruder and the second stage extruder It is more preferable that the resin temperature T2 (° C.) in the second stage extruder is higher than the resin temperature T1 (° C.) in the first stage extruder. In the first and second stage extruders, an antioxidant, a lubricant which is also a neutralizing agent for neutralizing chlorine components in the resin, an antistatic agent, a light stabilizer, an ultraviolet absorber, an antifogging agent. It can be melt kneaded with various additives such as an agent.

  The reason why the ½ isothermal crystallization time of the ethylene-α-olefin copolymer, that is, the crystallization speed can be adjusted by passing it through the extruder at least twice in the granulation step is not necessarily clear, but the first stage extrusion When the resin temperature in the machine is lower than the resin temperature in the second stage extruder, the MFR is in the range of 1 g / 10 min to 10 g / 10 min, and the ethylene-α-olefin copolymer has many short chain branches In the case of coalescence, it was found that the change in ½ isothermal crystallization time was significant. From this, the copolymer having a high molecular weight and having a short chain branch derived from α-olefin or the like inhibits crystallization by being entangled with each other, and then the crystallization is inhibited even when melt-kneaded at a high temperature. It is estimated that there is. The 1/2 isothermal crystallization time of the ethylene-α-olefin copolymer is measured by the method described in the examples described later.

The density of the ethylene -α- olefin copolymer is preferably not 930 kg / m ³ or more 950 kg / m ³ or less, more preferably 935 kg / m ³ or more 949kg / m ³ or less, more preferably 925 kg / m ³ It is 948 kg / m ³ or less. When the density of the ethylene-α-olefin copolymer is 930 kg / m ³ or more, the pressure resistance and durability performance of the silane-crosslinked polyethylene pipe obtained by molding the ethylene-α-olefin copolymer tends to be further improved. is there. In addition, the extrusion load during production of the pipe also tends to be reduced. On the other hand, when the density of the ethylene-α-olefin copolymer is 950 kg / m ³ or less, the gel fraction of the molded product can be maintained, and the balance between rigidity and flexibility can be balanced. Tend to be better.

  The density of the ethylene-α-olefin copolymer is not particularly limited, but can be adjusted by, for example, the amount of introduction with other α-olefin (also referred to as comonomer) mainly copolymerized with ethylene. The density of the ethylene-α-olefin copolymer is measured by the method described in Examples described later.

  The molecular weight distribution (Mw / Mn) based on the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined from gel permeation chromatography (GPC) of the ethylene-α-olefin copolymer is 2.5 or more and 5. It is preferably 0 or less, more preferably 3.0 or more and 4.7 or less, and still more preferably 3.4 or more and 4.5 or less. When the molecular weight distribution (Mw / Mn) is 2.5 or more, the resin pressure and the shear at the time of pipe extrusion molding tend to be reduced. Further, due to this, the extrusion moldability can be maintained, and the appearance is liable to be suppressed. Moreover, the load at the time of extrusion molding can be reduced, and the gel fraction and appearance of the silane-crosslinked polyethylene pipe tend to be improved. On the other hand, when the molecular weight distribution (Mw / Mn) is 5.0 or less, low molecular weight components that do not contribute to crosslinking tend to be reduced while maintaining excellent moldability. Moreover, it exists in the tendency for the softness | flexibility and gel fraction of a silane crosslinked polyethylene pipe to improve.

  The molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer is not particularly limited in order to make it 3.0 or more and 5.0 or less, but for example, using a supported metallocene catalyst described later, It can be adjusted by performing step polymerization. It can also be controlled by the polymerization temperature and the amount of chain transfer agent.

  The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer are obtained by gelling an orthodichlorobenzene solution in which the ethylene-α-olefin copolymer is dissolved. It can be determined by permeation chromatography (hereinafter also referred to as “GPC”) and based on a calibration curve prepared using commercially available monodisperse polystyrene. Specifically, it is measured by the method described in Examples described later.

The ethylene-α-olefin copolymer is obtained from gel permeation chromatography and FT-IR, and has a short chain branching distribution represented by the following formula (A) (hereinafter also simply referred to as “short chain branching distribution”). 0.1 or more and 2.0 or less, more preferably 0.2 or more and 1.5 or less, and still more preferably 0.2 or more and 1.0 or less.
Short chain branch distribution = (number of short chain branches per 1000 carbons when log M is 5.0) − (number of short chain branches per 1000 carbons when log M is 4.0) (A)
(In formula (A), M represents the molecular weight in gel permeation chromatography, and log M represents the logarithm of M with 10 as the base.)

In the present specification, as shown in FIG. 1, a plot of the number of short chain branches with respect to the molecular weight M is referred to as “short chain branch number distribution”, and log M is 5.0 (molecular weight: 10 ⁵ ). The difference obtained by subtracting the short chain branch number of the copolymer having a log M of 4.0 (molecular weight: 10 ⁴ ) from the short chain branch number of the polymer is referred to as “short chain branch distribution”. 1, the horizontal axis represents the logarithm of molecular weight M (LogM), the left vertical axis represents the differential molar mass distribution (dw / dLogM), and the right vertical axis represents the number of short chain branches per 1000 carbon atoms. . The solid line shows the distribution of the molecular weight M in Examples 1 and 8, and the plot shows the number of short chain branches per 1000 carbon atoms for each logarithm of the molecular weight M in Examples 1 and 8.

  That is, it can be inferred that the fact that the short chain branching distribution is 0.1 or more means that the short chain branching component is relatively selectively introduced into the high molecular weight component. When many short chain branches are introduced into the high molecular weight component, the short chain branches are entangled with each other, so that crystallization is easily inhibited. It can be inferred that the effect of this is expressed.

  On the other hand, the fact that the short chain branching distribution is 2.0 or less can be presumed to mean that a certain amount or more of the short chain branching component exists also in the low molecular weight component. Thereby, the fall of compatibility with a high molecular weight component with many short chain branching components can be suppressed, and it can prevent that a rough surface generate | occur | produces and the external appearance is impaired.

  Control of the short-chain branching distribution of the ethylene-α-olefin copolymer is not particularly limited, but it is preferable to use a supported geometrically constrained metallocene catalyst described later. It can also be controlled by introducing more α-olefin as a molar ratio in the copolymer, for example, 1.0% or more. Furthermore, short chain branching can be selectively introduced into the high molecular weight component by appropriately adjusting the polymerization conditions and the like. Specifically, (1) continuous slurry polymerization in which ethylene gas, a solvent, a catalyst, etc. are continuously fed into the polymerization and continuously discharged together with the produced ethylene-α-olefin copolymer, 2) The catalyst is fed from near the liquid level of the polymerization vessel, the comonomer is fed from the bottom of the polymerization vessel, (3) a hydrocarbon solvent having 6 to 8 carbon atoms is used in continuous slurry polymerization, and (4) polymerization. After the vessel, ethylene, hydrogen and α-olefin are removed by a flash tank, and further maintained by a buffer tank of a predetermined condition in a state where no raw material is supplied.

  Among the methods for controlling the short-chain branching distribution described above, it is more effective to hold the raw material in a buffer tank under specified conditions for a certain period of time without supply of the raw material after removing the raw material in the flash tank after the polymerization vessel. It is. Generally, in order to suppress abnormal polymerization, it is considered that the raw material should be removed immediately after the completion of polymerization. However, short chain branching can be selectively introduced into the high molecular weight component by aging for a certain period of time without the supply of raw materials after completion of the polymerization.

  The temperature of the buffer tank is preferably 65 ° C. or higher, more preferably 68 ° C. or higher, and further preferably 70 ° C. or higher. Further, the temperature of the buffer tank is preferably 80 ° C. or lower, and more preferably 75 ° C. or lower. In addition, in the case of the ethylene-alpha-olefin copolymer polymerized using the conventional Ziegler-Natta catalyst, many short chain branches are contained in the low molecular weight component. For this reason, radicals are likely to be generated in the tertiary carbon present in the low molecular weight component. In this case, since the low molecular weight component has high mobility and high collision probability, high molecular weight due to cross-linking between polyethylenes tends to occur. Thereby, MFR reduction (high molecular weight) at the time of silane graft modification occurs easily, and the extrusion load at the time of subsequent molding increases. Also, since the silane graft modification proceeds on low molecular weight components, the probability of participating in the overall silane crosslinking is low, and more organic peroxides and organic unsaturated silane compounds are required to increase the gel fraction of the molded product. Is required.

  Moreover, short chain branching distribution is calculated | required from a gel permeation chromatography and FT-IR, and is specifically calculated | required by the method as described in the Example mentioned later.

  In addition, the ethylene-α-olefin copolymer polymerized using the metallocene catalyst described in JP 2011-12208 A has a short chain branching distribution of 0, that is, the same regardless of the molecular weight. However, in this case, the crystallization inhibition due to the entanglement of the short chain branches is insufficient, and the effect of increasing the crystallization rate and improving the crosslinking rate is insufficient. (Equivalent to Comparative Example 9 in this specification)

  Furthermore, the silane cross-linked polyethylene pipe obtained by using an ethylene-α-olefin copolymer satisfying the above-mentioned constitutions and having a short-chain branching distribution in the above range is surprisingly improved in color tone. I found out that

[Method for producing ethylene-α-olefin copolymer]
In the production method of the ethylene-α-olefin copolymer of the present embodiment, ethylene and an α-olefin having 3 to 8 carbon atoms are copolymerized in the presence of the following supported geometrically constrained metallocene catalyst, It has the superposition | polymerization process which obtains the ethylene-alpha-olefin copolymer mentioned above.

<Supported geometrically constrained metallocene catalyst>
The supported geometrically constrained metallocene catalyst of the present embodiment is not particularly limited, but at least (a) a carrier material (hereinafter also referred to as “component (a)” or “(a)”), (a) an organoaluminum compound. (Hereinafter also referred to as “component (A)” and “(I)”), (c) transition metal compounds having a cyclic η-bonding anion ligand (hereinafter referred to as “component (U)”, “(U) ), And (d) an activator capable of forming a complex that reacts with the transition metal compound having the cyclic η-bonding anion ligand and exhibits catalytic activity (hereinafter referred to as “component (d)”). , “(D)”) is preferably a supported geometrically constrained metallocene catalyst.

(A) The carrier substance may be either an organic carrier or an inorganic carrier. Although it does not specifically limit as an organic support | carrier, For example, the C2-C10 alpha olefin (co) polymer is mentioned. Examples of the (co) polymer of the α-olefin having 2 to 10 carbon atoms include polyethylene, polypropylene, polybutene-1, ethylene-propylene copolymer, ethylene-butene-1 copolymer, and ethylene-hexene-1 copolymer. Polymer, propylene-butene-1 copolymer, propylene-divinylbenzene copolymer; aromatic unsaturated hydrocarbon polymer such as polystyrene, styrene-divinylbenzene copolymer; and polar group-containing polymer such as Polyacrylic acid ester, polymethacrylic acid ester, polyacrylonitrile, polyvinyl chloride, polyamide, and polycarbonate may be mentioned. As the inorganic carrier is not particularly limited, for _{example, SiO 2, Al 2 O 3} , MgO, TiO 2, B 2 O 3, CaO, ZnO, BaO, ThO, SiO 2 -MgO, SiO 2 -Al 2 O ₃ , inorganic oxides such as SiO ₂ —V ₂ O ₅ ; inorganic halogen compounds such as MgCl ₂ , AlCl ₃ , MnCl ₂ ; Na ₂ CO ₃ , K ₂ CO ₃ , CaCO ₃ , MgCO ₃ , Al ₂ (SO _{4 ) 3, BaSO 4, KNO 3} , Mg (NO 3) 2 carbonates inorganic, such as, sulfates and _{nitrates,; Mg (OH) 2,} Al (OH) 3, Ca (OH) 2 or the like hydroxides Is mentioned. Of these, the preferred support material is SiO ₂ . The particle diameter of the carrier material can take any value, but is preferably 1.0 μm or more and 100 μm or less, more preferably 2.0 μm or more and 50 μm or less, and even more preferably 3.0 μm or more and 10 μm or less. It is.

  (A) The support material is preferably treated with (a) an organoaluminum compound as necessary. Preferable (a) organoaluminum compound is not particularly limited, but, for example, alkylaluminum such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum; Hydrides; aluminum alkoxides such as diethylaluminum ethoxide and dimethylaluminum methoxide; and alumoxanes such as methylalumoxane, isobutylalumoxane, and methylisobutylalumoxane. Among these, trialkylaluminum and aluminum alkoxide are preferable, and trimethylaluminum, triethylaluminum, and triisobutylaluminum are more preferable.

The supported geometrically constrained metallocene catalyst can include (c) a transition metal compound having a cyclic η-bonding anion ligand (hereinafter also simply referred to as “transition metal compound”). Although the transition metal compound of this embodiment is not specifically limited, For example, it can represent with following formula (1).
L _l MX _p X ' _q (1)

  In formula (1), M represents a transition metal belonging to Group 4 of the periodic table having an oxidation number of +2, +3, or +4 and having η5 bond with one or more ligands L.

  In the formula (1), each L independently represents a cyclic η-bonding anion ligand. The cyclic η-bonding anion ligand is a cyclopentadienyl group, an indenyl group, a tetrahydroindenyl group, a fluorenyl group, a tetrahydrofluorenyl group, or an octahydrofluorenyl group, and up to 20 of these groups. From a hydrocarbon group containing a non-hydrogen atom, a halogen, a halogen-substituted hydrocarbon group, an aminohydrocarbyl group, a hydrocarbyloxy group, a dihydrocarbylamino group, a hydrocarbylphosphino group, a silyl group, an aminosilyl group, a hydrocarbyloxysilyl group, and a halosilyl group Optionally having 1 to 8 substituents each independently selected, and two Ls containing up to 20 non-hydrogen atoms, hydrocabadiyl, halohydrocarbadiyl, hydrocarbyleneoxy, hydro Carbyleneamino, siladiyl, halosiladiyl, a It may be linked by a divalent substituent such as aminosilane.

  In formula (1), each X is independently a monovalent anionic σ-bonded ligand having up to 60 non-hydrogen atoms, or a divalent anionic σ-bonded bond that binds to M in a divalent manner. A ligand or a divalent anionic σ-bonded ligand that binds to M and L with a monovalent valence each is shown. X ′ each independently represents a neutral Lewis base coordination compound selected from phosphine, ether, amine, olefin and conjugated diene, each having 4 to 40 carbon atoms.

  In formula (1), l represents an integer of 1 or 2. p represents an integer of 0, 1 or 2, and X is a monovalent anionic σ-bonded ligand or a divalent anionic σ-bonded configuration in which M and L are each bonded with a monovalent valence. When indicating a ligand, p represents an integer that is 1 or more less than the formal oxidation number of M, and when X represents a divalent anionic σ-bonded ligand that binds to M in a divalent manner, p is , Represents an integer that is 1 + 1 or more less than the formal oxidation number of M. Q represents an integer of 0, 1 or 2. The transition metal compound is preferably a compound in which l is 1 in the formula (1).

A suitable example of the transition metal compound is a compound represented by the following formula (2).

In the formula (2), M represents titanium, zirconium or hafnium having a formal oxidation number of +2, +3 or +4. In formula (2), each R ¹ independently represents hydrogen, a hydrocarbon group, a silyl group, a germyl group, a cyano group, a halogen, or a composite group thereof, each of which is up to 20 non-hydrogens. It may have an atom, and adjacent R ¹ may combine to form a divalent derivative such as hydrocarbadiyl, siladiyl, germaniyl or the like to form a ring.

In formula (2), X ″ each independently represents a halogen, a hydrocarbon group, a hydrocarbyloxy group, a hydrocarbylamino group or a silyl group, each having up to 20 non-hydrogen atoms, Two X ″ may form a neutral conjugated diene or divalent derivative having 5 to 30 carbon atoms. Y represents —O—, —S—, —NR ³ — or —PR ³ —, and Z represents SiR ³ ₂ , CR ³ ₂ , SiR ³ ₂ SiR ³ ₂ , CR ³ ₂ CR ³ ₂ , CR ^3. = CR ³ , CR ³ ₂ SiR ³ ₂ or GeR ³ ₂ , wherein R ³ independently represents an alkyl group having 1 to 12 carbon atoms or an allyl group. Moreover, n shows the integer of 1-3.

More preferred examples of the transition metal compound are compounds represented by the following formula (3) and the following formula (4).

In formulas (3) and (4), each R ¹ independently represents hydrogen, a hydrocarbon group, a silyl group, a germyl group, a cyano group, a halogen, or a composite group thereof, each of up to 20 Can have non-hydrogen atoms. M represents titanium, zirconium or hafnium. Z and Y are the same as those shown in the formula (2). X and X ′ are the same as those indicated by X ″ in the formula (2).

  In formulas (3) and (4), p represents 0, 1 or 2, and q represents 0 or 1, respectively. When p is 2 and q is 0, the oxidation number of M is +4 and X is halogen, hydrocarbon group, hydrocarbyloxy group, dihydrocarbylamide group, dihydrocarbyl phosphide group, hydrocarbyl sulfide group, silyl group A group or a composite group thereof having up to 20 non-hydrogen atoms.

  In the formulas (3) and (4), when p is 1 and q is 0, the oxidation number of M is +3 and X is an allyl group, 2- (N, N-dimethylaminomethyl) phenyl A stabilized anionic ligand selected from the group and 2- (N, N-dimethyl) -aminobenzyl group; whether the oxidation number of M is +4 and X represents a derivative of a divalent conjugated diene M and X together form a metallocyclopentene group.

  In formulas (3) and (4), when p is 0 and q is 1, respectively, the oxidation number of M is +2, and X ′ is a neutral conjugated or non-conjugated diene, optionally It may be substituted with one or more hydrocarbon groups and X ′ may contain up to 40 carbon atoms, forming a π-type complex with M.

Further preferred examples of the transition metal compound are compounds represented by the following formulas (5) and (6).

In formulas (5) and (6), each R ¹ independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. M represents titanium, and Y represents —O—, —S—, —NR ³ —, or —PR ³ —. Z represents SiR ³ ₂ , CR ³ ₂ , SiR ³ ₂ SiR ³ ₂ , CR ³ ₂ CR ³ ₂ , CR ³ = CR ³ , CR ³ ₂ SiR ³ ₂ , or GeR ³ ₂ , wherein R ³ represents Independently represents hydrogen or a hydrocarbon group, hydrocarbyloxy group, silyl group, halogenated alkyl group, halogenated allyl group, or a composite group thereof, which may have up to 20 non-hydrogen atoms. and optionally, two R ³ together, or R ³ and R ³ in Y in Z may be a ring I coupled with in Z. X and X ′ are the same as those shown in the formula (3) or (4).

  In formulas (5) and (6), p represents 0, 1 or 2, and q represents 0 or 1, respectively. However, when p is 2 and q is 0, the oxidation number of M is +4 and each X independently represents a methyl group or a benzyl group. When p is 1 and q is 0, the oxidation number of M is +3 and X represents 2- (N, N-dimethyl) aminobenzyl, or the oxidation number of M is +4 and X Represents 2-butene-1,4-diyl. When p is 0 and q is 1, the oxidation number of M is +2 and X ′ is 1,4-diphenyl-1,3-butadiene or 1,3-pentadiene. These dienes are examples of asymmetric dienes that form metal complexes, and are actually a mixture of geometric isomers.

The supported geometrically constrained metallocene catalyst includes (d) an activator (hereinafter, also simply referred to as “activator”) capable of forming a complex that reacts with a transition metal compound and exhibits catalytic activity. Generally, in a metallocene catalyst, a transition metal compound and a complex formed by the activator exhibit high olefin polymerization activity as a catalytically active species. In the present embodiment, the activator is not particularly limited, and examples thereof include a compound represented by the following formula (7).
[L−H] ^{d +} [M _m Q _p ] ^d− (7)

In the formula (7), [L—H] ^{d +} represents a proton-providing Bronsted acid, and L represents a neutral Lewis base. [M _m Q _p ] ^d− represents a compatible non-coordinating anion, M represents a metal or metalloid selected from Groups 5 to 15 of the periodic table, and Q is independently selected. Represents a hydride, a dialkylamide group, a halide, an alkoxy group, an allyloxy group, a hydrocarbon group, or a substituted hydrocarbon group having up to 20 carbon atoms, and Q as a halide is 1 or less. Further, m represents an integer of 1 to 7, p represents an integer of 2 to 14, d represents an integer of 1 to 7, and pm = d.

A more preferred example of the activator is a compound represented by the following formula (8).
[L−H] ^{d +} [M _m Q _n (G _q (T−H) _r ) _z ] ^d− (8)

In formula (8), [L-H] ^{d +} represents a proton-providing Bronsted acid, and L represents a neutral Lewis base. [M _m Q _n (G _q ( ^TH ) _r ) _z ] ^{d −} represents a compatible non-coordinating anion, and M is selected from Groups 5 to 15 of the periodic table. Q represents a metal or a metalloid, and each Q independently represents a hydride, a dialkylamide group, a halide, an alkoxy group, an allyloxy group, a hydrocarbon group, or a substituted hydrocarbon group having up to 20 carbon atoms. Is 1 or less. G represents a polyvalent hydrocarbon group having an r + 1 valence bonded to M and T, and T represents O, S, NR, or PR. Here, R represents hydrocarbyl, trihydrocarbylsilyl group, trihydrocarbylgermanium group or hydrogen. M represents an integer of 1 to 7, n represents an integer of 0 to 7, q represents an integer of 0 or 1, r represents an integer of 1 to 3, and z represents 1 The integer of -8 is shown, d shows the integer of 1-7, and is n + z-m = d.

A further preferred example of the activator is a compound represented by the following formula (9).
[LH] ⁺ [BQ ₃ Q ¹ ] ^- (9)

In the formula (9), [L—H] ⁺ represents a proton-providing Bronsted acid, and L represents a neutral Lewis base. [BQ ₃ Q ¹ ] ⁻ represents a compatible non-coordinating anion, B represents a boron element, Q independently represents a pentafluorophenyl group, and Q ¹ represents a substituent. As a substituted allyl group having 6 to 20 carbon atoms having one OH group.

  The proton-providing Bronsted acid is not particularly limited, and examples thereof include triethylammonium, tripropylammonium, tri (n-butyl) ammonium, trimethylammonium, tributylammonium, tri (n-octyl) ammonium, and diethylmethylammonium. , Dibutylmethylammonium, dibutylethylammonium, dihexylmethylammonium, dioctylmethylammonium, didecylmethylammonium, didodecylmethylammonium, ditetradecylmethylammonium, dihexadecylmethylammonium, dioctadecylmethylammonium, diicosylmethylammonium, And trialkyl group-substituted ammonium carboxyls such as bis (hydrogenated tallow alkyl) methylammonium ON; N, N-, such as N, N-dimethylanilinium, N, N-diethylanilinium, N, N-2,4,6-pentamethylanilinium, and N, N-dimethylbenzylanilinium A dialkylanilinium cation; a triphenylcarbonium cation.

  The compatible non-coordinating anion is not particularly limited, and examples thereof include triphenyl (hydroxyphenyl) borate, diphenyl-di (hydroxyphenyl) borate, triphenyl (2,4-dihydroxyphenyl) borate, tri ( p-tolyl) (hydroxyphenyl) borate, tris (pentafluorophenyl) (hydroxyphenyl) borate, tris (2,4-dimethylphenyl) (hydroxyphenyl) borate, tris (3,5-dimethylphenyl) (hydroxyphenyl) Borate, tris (3,5-di-trifluoromethylphenyl) (hydroxyphenyl) borate, tris (pentafluorophenyl) (2-hydroxyethyl) borate, tris (pentafluorophenyl) (4-hydroxybutyl) borate Tris (pentafluorophenyl) (4-hydroxy-cyclohexyl) borate, tris (pentafluorophenyl) (4- (4′-hydroxyphenyl) phenyl) borate, and tris (pentafluorophenyl) (6-hydroxy-2-naphthyl) ) Borate. These compatible non-coordinating anions are also referred to as “borate compounds”. From the viewpoint of catalytic activity and the viewpoint of reducing the total content of Al, Mg, Ti, Zr and Hf, the activator of the supported geometrically constrained metallocene catalyst is preferably a borate compound. Preferred borate compounds include tris (pentafluorophenyl) (hydroxyphenyl) borate.

As the activator, an organometallic oxy compound having a unit represented by the following formula (10) can also be used.
(In the formula (10), M ² represents a metal of Group 13 to Group 15 of the periodic table, or a metalloid, and each R independently represents a hydrocarbon group or substituted hydrocarbon group having 1 to 12 carbon atoms. N represents the valence of the metal M2, and m represents an integer of 2 or more.)

Another preferred example of the activator is an organoaluminum oxy compound containing a unit represented by the following formula (11).
(In formula (11), R represents an alkyl group having 1 to 8 carbon atoms, and m represents an integer of 2 to 60.)

A more preferred example of the activator is methylalumoxane containing a unit represented by the following formula (12).
(In formula (12), m represents an integer of 2 to 60.)

In addition to the components (a) to (d), an organoaluminum compound can be used as a catalyst as necessary. Although it does not specifically limit as an organoaluminum compound, For example, the compound represented by following formula (13) is mentioned.
AlR _n X _3-n (13)

  In formula (13), R represents a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms or an allyl group having 6 to 20 carbon atoms, X represents a halogen, hydrogen or alkoxyl group, n shows the integer of 1-3. The organoaluminum compound may be a mixture of compounds represented by formula (13).

  The catalyst can be obtained by supporting the component (a), the component (c), and the component (d) on the component (a). The method for supporting component (a), component (c), and component (e) is not particularly limited. For example, an inert solvent that can dissolve component (a), component (c), and component (d), respectively. A method in which the solvent is distilled off after being dissolved in and mixed with component (a); after dissolving component (b), component (c) and component (d) in an inert solvent, it is not in the range where no solid precipitates. A method of concentrating this, and then adding component (a) in such an amount that the entire amount of the concentrate can be retained in the particles; component (a) is first loaded with component (a) and component (e), and then component (C) A method of supporting (c); a method of supporting component (a), (a), (d), and (c) sequentially. The component (c) and the component (d) of the present embodiment are preferably liquid or solid. In addition, component (a), component (c), and component (d) may be used after being diluted with an inert solvent during loading.

  Examples of the inert solvent include, but are not limited to, aliphatic hydrocarbons such as isobutane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic carbons such as cyclopentane, cyclohexane, and methylcyclopentane. Hydrogen; aromatic hydrocarbons such as benzene, toluene and xylene; and mixtures thereof. Such an inert solvent is preferably used after removing impurities such as water, oxygen, and sulfur using a desiccant, an adsorbent, or the like.

Component (A) is preferably 1.0 × 10 ^{−5 to} 1.0 × 10 ⁻¹ mol in terms of Al atom, more preferably 1.0 × 10 ⁻⁴ to 1.0 g of component (A). 5.0 × 10 −2 mol and component (c) are preferably 1.0 × 10 ^{−7 to} 1.0 × 10 ⁻³ mol, more preferably 5.0 × 10 ^{−7 to} 5.0 × 10. ^-4 mol, the component (d) is preferably in the range of 1.0 × 10 ^{−7 to} 1.0 × 10 ⁻³ mol, more preferably in the range of 5.0 × 10 ^{−7 to} 5.0 × 10 ⁻⁴ mol. It is. The amount of each component used and the loading method are determined by activity, economy, powder characteristics, scale in the reactor, and the like. The obtained supported geometrically constrained metallocene catalyst was washed by a method such as decantation or filtration using an inert solvent for the purpose of removing organoaluminum compounds, borate compounds and titanium compounds not supported on the carrier. You can also

  The series of operations such as dissolution, contact, and washing are preferably performed at a temperature of −30 ° C. or more and 80 ° C. or less selected for each unit operation. A more preferable range of such temperature is 0 ° C. or more and 50 ° C. or less. The series of operations for obtaining the supported geometrically constrained metallocene catalyst is preferably performed in a dry inert atmosphere.

  The supported geometrically constrained metallocene catalyst can be used for homopolymerization of ethylene or copolymerization of ethylene and α-olefin, but an organoaluminum compound is added as an additional component to prevent poisoning of solvents and reactions. They can also be used together. Although it does not specifically limit as a preferable organoaluminum compound, For example, alkyl aluminum, such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum; alkylaluminum hydride, such as diethylaluminum hydride and diisobutylaluminum hydride; Examples include aluminum alkoxides such as diethylaluminum ethoxide; alumoxanes such as methylalumoxane, isobutylaluminoxane, and methylisobutylalumoxane. Among these, trialkylaluminum and aluminum alkoxide are preferable. More preferred is triisobutylaluminum.

  The polymerization method of the ethylene-α-olefin copolymer is preferably a slurry polymerization method. In the case of performing polymerization, generally, the polymerization pressure is preferably 0.1 MPaG or more and 10 MPaG or less, more preferably 0.3 MPaG or more and 3.0 MPaG or less. The polymerization temperature is preferably 20 ° C. or higher and 115 ° C. or lower, more preferably 50 ° C. or higher and 85 ° C. or lower.

  As the solvent used in the slurry polymerization method, the above-described inert solvent is preferable, and an inert hydrocarbon solvent is more preferable. Examples of the inert hydrocarbon solvent include hydrocarbon solvents having 6 to 8 carbon atoms, specifically, aliphatic hydrocarbons such as isobutane, pentane, hexane, heptane, and octane; cyclopentane, cyclohexane, methylcyclopentane, and the like. Alicyclic hydrocarbons; and mixtures thereof.

  The polymerization method of the ethylene-α-olefin copolymer is preferably a continuous polymerization. By continuously supplying ethylene gas, solvent, catalyst, etc. into the polymerization and continuously discharging together with the generated ethylene-α-olefin copolymer, partial high-temperature conditions due to rapid ethylene reaction are suppressed. Therefore, the inside of the polymerization system tends to become more stable. When ethylene reacts in a uniform state, the broadening of the molecular weight distribution tends to be suppressed.

  Adjustment of the melt flow rate of the ethylene-α-olefin copolymer can be accomplished by allowing hydrogen to be present in the polymerization or changing the polymerization temperature, as described, for example, in DE-A-3127133. It can be adjusted depending on the situation. When hydrogen is added as a chain transfer agent in the polymerization, the molecular weight of the ethylene-α-olefin copolymer tends to be easily adjusted to the desired range of this embodiment. When hydrogen in the polymerization is added, the molar fraction of hydrogen is preferably 0 mol% or more and 45 mol% or less, more preferably 0 mol% or more and 30 mol% or less, and 0 mol% or more and 20 mol% or less. Further preferred.

  The solvent separation method in the method for producing an ethylene-α-olefin copolymer in the present embodiment can be performed by a decantation method, a centrifugal separation method, a filter filtration method, or the like, but the ethylene-α-olefin copolymer and the solvent. A centrifugal separation method with good separation efficiency is more preferable. The amount of the solvent contained in the ethylene-α-olefin copolymer after the solvent separation is not particularly limited, but is preferably 70% by mass or less, more preferably based on the weight of the ethylene-α-olefin copolymer. It is 60 mass% or less, More preferably, it is 50 mass% or less.

  The method for deactivating the catalyst used for synthesizing the ethylene-α-olefin copolymer is not particularly limited, but it is preferably carried out after separating the ethylene-α-olefin copolymer and the solvent.

  Although it does not specifically limit as a chemical | medical agent which deactivates a catalyst, For example, oxygen, water, alcohols, glycols, phenols, carbon monoxide, carbon dioxide, ethers, carbonyl compounds, and alkynes are mentioned.

  The drying in the method for producing an ethylene-α-olefin copolymer is preferably carried out in a state where an inert gas such as nitrogen or argon is circulated. Further, the drying temperature is preferably 50 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 140 ° C. or lower, and further preferably 50 ° C. or higher and 130 ° C. or lower. If the drying temperature is 50 ° C. or higher, efficient drying tends to be possible. On the other hand, if the drying temperature is 150 ° C. or lower, drying tends to be possible in a state in which decomposition and crosslinking of the ethylene-α-olefin copolymer are suppressed. In addition to the above components, other known components useful for the production of an ethylene-α-olefin copolymer can be included.

(Resin composition)
The resin composition of this embodiment contains the said ethylene-alpha-olefin copolymer and antioxidant, and content of the substance which functions as this antioxidant is 200 mass ppm or less.

<Substances that function as antioxidants>
The content of a substance that functions as an antioxidant of the present embodiment (hereinafter also simply referred to as “antioxidant”) is preferably 200 ppm by mass or less, more preferably 100 ppm by mass or less, and still more preferably. Is 70 mass ppm or less, more preferably 50 mass ppm or less. When the content is 200 ppm by mass or less, when the silane graft-modified polyethylene resin composition is prepared, it is suppressed that the radicals are deactivated by the reaction of the antioxidant and the organic peroxide, A large amount of organic peroxide is not required at the time of the silane graft modification reaction, which tends to suppress the problem of odor. Further, since a large amount of organic peroxide is not required, side reactions such as decomposition and crosslinking reaction of the ethylene-α-olefin copolymer can be suppressed, and a decrease in silane graft modification efficiency can be suppressed. Therefore, the content of the antioxidant is preferably 100 mass ppm or less, but from the viewpoint of preventing side reactions during silane graft modification, it is more preferable that no antioxidant is contained.

  The antioxidant is not particularly limited as long as it has a function of capturing oxygen molecules, ozone, or oxygen radicals. For example, dibutylhydroxytoluene, pentaerythryl-tetrakis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate], and octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate.

  In addition, the resin composition of the present embodiment includes, as necessary, other additives such as a lubricant, an antistatic agent, a light stabilizer, and an ultraviolet absorber that are also neutralizers for neutralizing chlorine components in the resin. Agents, antifogging agents and the like may be included.

[Method for producing resin composition]
The method for producing a resin composition of the present embodiment includes a granulation step in which the ethylene-α-olefin copolymer is continuously passed through an extruder at least twice to knead and granulate to obtain a resin composition. . In the granulation process, changing the temperature conditions of the first-stage extruder and the second-stage extruder, particularly the second-stage extrusion, rather than the resin temperature T1 (° C.) in the first-stage extruder. It is more preferable that the resin temperature T2 (° C.) in the machine is high. This makes it possible to make the ½ isothermal crystallization time longer.

  In the first and second stage extruders, an antioxidant, a lubricant that is also a neutralizing agent for neutralizing chlorine components in the resin, an antistatic agent, a light stabilizer, an ultraviolet absorber, an antifogging agent. It can be melt kneaded with various additives such as an agent.

[Silane graft-modified polyethylene resin composition]
The silane graft-modified polyethylene resin composition of the present embodiment is 0.025 parts by mass or more and 1.0 part by mass with respect to 100 parts by mass of the ethylene-α-olefin copolymer and the ethylene-α-olefin copolymer. The following organic peroxide and 0.1 to 1.5 parts by mass of an organic unsaturated silane compound are included.

<Organic peroxide>
The organic peroxide of this embodiment can be decomposed into radicals in the extrusion process, and the organic unsaturated silane compound can be graft-modified to the ethylene-α-olefin copolymer. An organic peroxide is 0.025 mass part or more and 1.0 mass part or less with respect to 100 mass parts of ethylene-alpha-olefin copolymers. When the content of the organic peroxide is 0.025 parts by mass or more, the graft modification reaction of the ethylene-α-olefin copolymer and the organic unsaturated silane compound proceeds efficiently. Moreover, it is economically excellent because content of an organic peroxide is 1.0 mass part or less.

  Examples of the organic peroxide include the already known dicumyl peroxide, 2,5-dimethyl-2,5-di- (t-butyl-oxy) -hexyne-3, 1,3-bis- (t-butyl- Oxy-isopropyl) -benzene, t-butylcumyl peroxide, 4,4, -di- (t-butylperoxy) valeric acid-butyl ester, 1,1-di- (t-butylperoxy) -3,3 , 5-trimethylcyclohexanexin-3, benzoyl peroxide, dicyclobenzoperoxide, di-t-butyl peroxide, lauroyl peroxide, di-t-butylperoxyisophthalate, etc., especially dicumyl peroxide Is economical and preferred.

<Organic unsaturated silane compound>
The organounsaturated silane compound of this embodiment is 0.1 to 1.5 parts by mass with respect to 100 parts by mass of the ethylene-α-olefin copolymer. When the content of the organic unsaturated silane compound is 0.1 parts by mass or more, silane crosslinking of the silane graft-modified polyethylene proceeds sufficiently. In addition, when the content of the organic unsaturated silane compound is 1.5 parts by mass or less, an increase in the load at the time of extrusion of the eyes and the pipe occurs, and the extrudability of the pipe becomes poor, Odor generation can be suppressed during molding. Moreover, since an organic unsaturated silane compound is expensive, it is economically preferable.

  The organic unsaturated silane compound is not particularly limited as long as it can crosslink an ethylene-α-olefin copolymer with silane. For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, allyltrimethoxy Examples include silane, vinylmethyldimethoxysilane, and vinyltris (β-methoxyethoxy) silane. Such an organic unsaturated silane compound can react with a radical in the ethylene-α-olefin copolymer generated by the action of the organic peroxide to cause graft modification reaction to the ethylene-α-olefin copolymer.

<Substances that function as antioxidants>
The silane graft-modified polyethylene resin composition of this embodiment may further contain a substance that functions as an antioxidant (hereinafter also simply referred to as “antioxidant”). Content of antioxidant becomes like this. Preferably it is 100 mass ppm or less, More preferably, it is 70 mass ppm or less, More preferably, it is 50 mass ppm or less. When the content is 100 mass ppm or less, it is possible to prevent radicals from being deactivated by the reaction of the antioxidant and the organic peroxide, and a large amount of organic peroxide is required during the silane graft modification reaction. It tends to suppress the problem of odor. Further, since a large amount of organic peroxide is not required, side reactions such as decomposition and crosslinking reaction of the ethylene-α-olefin copolymer can be suppressed, and a decrease in silane graft modification efficiency can be suppressed. Therefore, the content of the antioxidant is preferably 100 mass ppm or less, but from the viewpoint of preventing side reactions during silane graft modification, it is more preferable that no antioxidant is contained.

  The antioxidant is not particularly limited as long as it has a function of capturing oxygen molecules, ozone, or oxygen radicals. For example, dibutylhydroxytoluene, pentaerythryl-tetrakis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate], and octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate.

  In the present embodiment, the additive content is determined by extracting the additive in the silane-graft-modified polyethylene resin composition or the silane-crosslinked polyethylene pipe by Soxhlet extraction with tetrahydrofuran (THF) for 6 hours, and subjecting the extract to liquid chromatography. It can be determined by separation and quantification by chromatography.

[Method for producing silane-grafted modified polyethylene resin]
Although the manufacturing method of the silane graft modified polyethylene resin of this embodiment is not specifically limited, For example, the following methods are mentioned. That is, to 100 parts by mass of the ethylene-α-olefin copolymer before modification, 0.05 to 1.0 parts by mass of organic peroxide and 0.1 to 1.5 parts by mass of organic peroxide. In this method, an unsaturated silane compound is added, mixed with an appropriate mixer such as a Henschel mixer, and heated and kneaded at 140 to 250 ° C. with an extruder, a Banbury mixer or the like, and then heat grafted.

  In producing the silane-grafted modified polyethylene resin composition, an antioxidant may be further added to the ethylene-α-olefin copolymer as necessary, and kneading and granulation may be performed. The temperature at this time is preferably 220 ° C. or lower, more preferably 200 ° C. or lower, and further preferably 190 ° C. or lower.

[Silane-crosslinked polyethylene pipe]
The silane cross-linked polyethylene pipe of the present embodiment includes a cross-linked product of the silane graft-modified polyethylene resin composition described above. The method for producing the crosslinked product is as follows.

[Method for producing silane-crosslinked polyethylene molded article]
The method for producing a silane-crosslinked polyethylene molded body according to this embodiment includes a step of molding and crosslinking the above-described silane graft-modified polyethylene resin composition. As a specific example of this step, for example, a silanol condensation catalyst is added to a silane graft-modified polyethylene resin composition, melt mixed with an extruder, molded, and the resulting molded product is crosslinked with silane groups in the presence of warm water or water vapor. It is a process.

  The gel fraction of the silane-crosslinked polyethylene pipe of the present embodiment is preferably 70% or more, more preferably 75% or more, and further preferably 80% or more. The upper limit of the gel fraction is not particularly limited, but 100% is preferable. The gel fraction is determined when the ethylene-α-olefin copolymer is uniformly grafted with an organic unsaturated silane compound by a silane graft modification reaction, and the silane graft modified polyethylene resin composition is uniformly crosslinked with a silanol condensation catalyst. It is considered to be a high value. Empirically, silane-crosslinked polyethylene pipes with high gel fractions are excellent in mechanical strength such as short-term and long-term hot internal pressure creep, but in order to obtain high gel fractions in conventional ethylene-α-olefin copolymers. Needs to use a large amount of an organic unsaturated silane compound. On the other hand, the silane graft-modified polyethylene resin composition containing the ethylene-α-olefin copolymer of this embodiment can obtain a high gel fraction even with a small amount of an organic unsaturated silane compound. A gel fraction is measured by the method as described in the Example mentioned later.

<Silanol condensation catalyst>
The silanol condensation catalyst of this embodiment can crosslink the organic unsaturated silane compound grafted to the ethylene-α-olefin copolymer in the presence of warm water or water vapor. Although it does not specifically limit as a silanol condensation catalyst, For example, already well-known dibutyltin dilaurate, stannous acetate, stannous caprylate, tin naphthenate, zinc caprylate, iron 2-ethylhexanoate, cobalt naphthenate , Tetrabutyl titanate, ethylamine, dibutylamine, dibutyltin dilaurate, dibutyltin diacetate, and dibutyl octate. The method for adding these silanol condensation catalysts is not particularly limited.

  Hereinafter, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to the following examples. First, the physical properties and measurement methods for evaluation and evaluation criteria will be described below.

(Physical property 1) Melt flow rate (MFR)
About each ethylene-alpha-olefin copolymer obtained by the Example and the comparative example, the melt flow rate was measured by 190 degreeC and the load of 2.16 kg according to ASTM-D-1238.

(Physical property 2) Crystallization start temperature (Cp Onset) and 1/2 isothermal crystallization time by differential scanning calorimeter (DSC) method Using DSC8000 manufactured by Perkin Elmer Co., Ltd., sample weight 5 mg, 200 ° C./min under nitrogen atmosphere Is heated to 180 ° C., held at 180 ° C. for 5 minutes, and then cooled to 40 ° C. from 180 ° C. at a temperature decrease rate of 10 ° C./min. Onset) was measured.

  Further, a DSC8000 manufactured by Perkin Elmer was used, and measurement was performed at a sample weight of 5 mg under a nitrogen atmosphere. After maintaining at 50 ° C. for 1 minute, the temperature is increased to 190 ° C. at a temperature increase rate of 200 ° C./min, maintained at 190 ° C. for 5 minutes, and cooled to a crystallization start temperature (Cp Onset) + 5 ° C. at a temperature decrease rate of 120 ° C./min. Then, the peak top time (1/2 isothermal crystallization time) in isothermal crystallization when held at that temperature was measured.

(Physical property 3) Density About each ethylene-alpha-olefin copolymer obtained by the Example and the comparative example, the density was measured by the density gradient tube method based on JISK6760.

(Physical property 4) Mw / Mn
A sample solution was prepared by introducing 15 mL of o-dichlorobenzene into 20 mg of the ethylene-α-olefin copolymer obtained in Examples and Comparative Examples and stirring at 150 ° C. for 1 hour, and gel permeation chromatography (GPC). ) Was measured. Separately, Mw of commercially available standard polystyrene was multiplied by a coefficient of 0.43 to obtain a molecular weight in terms of polyethylene, and a primary calibration line was created from a plot of elution time and molecular weight in terms of polyethylene. Based on the GPC measurement results and the calibration curve, the number average molecular weight (Mn), the weight average molecular weight (Mw), and the molecular weight distribution (Mw / Mn) were determined. In addition, the apparatus and conditions used for the measurement were as follows.
Apparatus: 150-C ALC / GPC manufactured by Waters
Detector: RI detector Mobile phase: o-dichlorobenzene (for high performance liquid chromatograph)
Flow rate: 1.0 mL / min Column: What connected one AT-807S by Showa Denko KK and two TSK-gelGMH-H6 by Tosoh KK was used.
Column temperature: 140 ° C

(Physical property 5) Short chain branching distribution For each ethylene-α-olefin copolymer obtained in Examples and Comparative Examples, FT-IR (Perkin) was used as a detector online on GPC (“Alliance GPCV 2000” manufactured by Waters). Elmer Co., Ltd. "FT-IR 1760X") was connected, and FT-IR measurement was performed simultaneously with GPC measurement.

That is, FT-IR measurement of the copolymer was performed for each molecular weight. Then, from the obtained FT-IR measurement results, the absorbance I (—CH ₂ —) (absorption wave number: 2,925 cm ⁻¹ ) attributed to the methylene group and the absorbance I (—CH ₃ ) attributed to the methyl group ( I (—CH ₃ ) / I (—CH ₂ —), which is a ratio to the absorption wave number; 2,960 cm ⁻¹ ), was calculated. Separately, for polyethylene whose short chain branching number is known by ¹³ C-NMR measurement, I (—CH ₃ ) / I (—CH ₂ —) is also measured, and the short chain branching number and I (—CH ₃ ) are measured. ) / I (—CH ₂ —) was used to create a calibration curve.

Based on the measurement result of I (—CH ₃ ) / I (—CH ₂ —) and the calibration curve, the number of short chain branches per 1000 carbons in the copolymer having a log M of 5.0 and the log M The number of short chain branches per 1000 carbons in a copolymer having a value of 4.0 was calculated. The short chain branching distribution was a value obtained by subtracting the short chain branching number at a log M of 4.0 from the short chain branching number at a log M of 5.0.

(Evaluation 1) Gel fraction and arrival time of 65% of gel fraction 10 g of each silane-crosslinked polyethylene pipe obtained in Examples and Comparative Examples was cut and extracted with a Soxhlet extractor for 10 hours using a xylene solvent. The amount was measured, and the gel fraction was determined by the following formula.
Gel fraction (%) = extraction remaining amount (g) / 10 (g) × 100

  In addition, 20 pieces of 10 g of resin (hereinafter referred to as a sample) were cut from a pipe before crosslinking having a nominal diameter of 13 manufactured by the method described below, and immersed in hot water at 80 ° C. or 95 ° C. Each sample was taken out of the hot water every 20 minutes in the case of 80 ° C. and every 10 minutes in the case of 95 ° C., and the gel fraction was measured by the method described above. The crosslinking rate was evaluated by the time during which a sample having a gel fraction exceeding 65% was obtained.

(Evaluation 2) Pipe Extrusion Load The extrusion load at the time of silane-crosslinked polyethylene pipe molding in Examples and Comparative Examples was evaluated according to the following criteria.
○: The load during extrusion was small, and there was no problem in production.
Δ: There was a slight load during extrusion, but there was no problem in production.
X: The load at the time of extrusion was large, and the pipe could not be molded.

(Evaluation 3) Pipe Appearance The appearance of each silane-crosslinked polyethylene pipe obtained in Examples and Comparative Examples was evaluated according to the following criteria.
○: Scratches on the surface and regular stripes on the inner surface did not exist and were smooth.
(Triangle | delta): Either the crack on the surface or the regular stripe pattern existed on the inner surface, or the inner surface was not smooth.
X: Scratches on the surface and / or regular stripes on the inner surface were not smooth.

(Evaluation 4) Color tone of cross-linked pipe Yellow color (b value) was measured with a Z-300A type color sensor manufactured by Nippon Denshoku Industries Co., Ltd. as the color tone of the cross-linked pipe. The case where the b value was -1 or less was marked with ◯, and the case where the b value was larger than −1 was marked with ×.

[Preparation of catalyst]
[Preparation of supported geometrically constrained metallocene catalyst [Ia]]
The catalyst support silica that had been sufficiently washed and dried was calcined at 600 ° C. for 5 hours in a nitrogen atmosphere and dehydrated to obtain dehydrated silica. The amount of surface hydroxyl groups of dehydrated silica was 1.85 mmol / g. In a 1.8 L autoclave, 40 g of this dehydrated silica was dispersed in 800 mL of hexane to obtain a slurry. While maintaining the resulting slurry at 20 ° C. with stirring, 80 mL of a hexane solution of triethylaluminum (concentration 1 mol / L) was added, and then stirred for 2 hours to react the triethylaluminum with the surface hydroxyl group of silica to obtain the surface hydroxyl group of silica. A hexane slurry of component [a] capped with triethylaluminum was obtained.

  On the other hand, 200 mmol of [(Nt-butylamide) (tetramethyl-η5-cyclopentadienyl) dimethylsilane] titanium dimethyl (hereinafter referred to as “titanium complex”) was added to Isopar E (registered trademark) [Exxon Chemical Co., Ltd. (US) Hydrocarbon mixture product name] Dissolved in 1000 mL, added 20 mL of 1 mol / L hexane solution of n-butylethylmagnesium, further added hexane to adjust the titanium complex concentration to 0.1 mol / L, Component [b] was obtained.

  Further, 5.7 g of bis (hydrogenated tallow alkyl) methylammonium-tris (pentafluorophenyl) (4-hydroxyphenyl) borate (hereinafter referred to as “borate”) was added to 50 mL of toluene and dissolved, and borate Of 100 mmol / L in toluene was obtained. To this toluene solution of borate, 5 mL of a 1 mol / L hexane solution of diethylaluminum ethoxide was added at room temperature, and further hexane was added so that the borate concentration in the solution was 70 mmol / L. Then, it stirred at room temperature for 1 hour and obtained the reaction mixture containing a borate.

  46 mL of this reaction mixture containing borate and 32 mL of the component [b] obtained above were simultaneously added to 800 mL of the slurry of the component [a] obtained above with stirring at 20 to 25 ° C., and further stirred for 3 hours. The titanium complex and borate were reacted and precipitated and physically adsorbed on silica. Thereafter, the supernatant containing the unreacted borate-titanium complex in the obtained reaction mixture is removed by decantation, whereby the supported geometrically constrained metallocene catalyst [I -A] (simply indicated as “Ia” in the table).

  In the same manner, the following supported geometrically constrained metallocene catalysts [Ib] and [Ic] were prepared.

[Supported geometrically constrained metallocene catalyst [Ib]]
The supported geometrically constrained metallocene catalyst [I-a] except that the titanium complex was replaced with [(Nt-butylamide) (tetramethyl-η5-cyclopentadienyl) dimethylsilane] titanium-1,3-pentadiene. Thus, a supported geometrically constrained metallocene catalyst [Ib] (simply indicated as “Ib” in the table) was obtained.

[Supported geometrically constrained metallocene catalyst [Ic]]
Except for replacing the titanium complex with [(Nt-butylamide) (tetramethyl-η5-cyclopentadienyl) dimethylsilane] titanium dichloride, in accordance with the preparation of the supported geometrically constrained metallocene catalyst [Ia] Thus, a supported geometrically constrained metallocene catalyst [Ic] (simply indicated as “Ic” in the table) was obtained.

[Preparation of Ziegler-Natta catalyst [II]]
(1) Synthesis of carrier 1,000 mL of a 2 mol / L trichlorosilane hexane solution was charged into a fully nitrogen-substituted 8 L stainless steel autoclave and stirred at 65 ° C. with AlMg ₅ (C ₄ H ₉ ) ₁₁ (OC ₄ A hexane solution of 2,550 mL of an organic magnesium compound represented by H ₉ ) ₂ (corresponding to 2.68 mol of magnesium) was added dropwise over 4 hours, and the reaction was further continued with stirring at 65 ° C. for 1 hour. After completion of the reaction, the supernatant was removed and washed 4 times with 1,800 mL of hexane. As a result of analyzing this solid, magnesium contained per gram of the solid was 8.31 mmol.

(2) Preparation of solid catalyst component [II] While stirring at 10 ° C. to 1,970 mL of hexane slurry containing 110 g of the above carrier, 110 mL of 1 mol / L titanium tetrachloride hexane solution and 1.0 mol / L AlMg ₅ (C 110 mL of a hexane solution of an organomagnesium compound represented by ₄ H ₉ ) ₁₁ (OSiH) ₂ was simultaneously added over 1 hour. After the addition, the reaction was continued at 10 ° C. for 1 hour. After completion of the reaction, the supernatant was removed by decantation and washed twice with hexane to prepare a solid catalyst component [II] (simply indicated as “II” in the table).

[Example 1]
An ethylene-α-olefin copolymer was obtained by the continuous slurry polymerization method shown below. Specifically, continuous polymerization was performed using a Bessel type 340L polymerization reactor equipped with a stirring device under conditions of a polymerization temperature of 70 ° C., a polymerization pressure of 0.98 MPa, and an average residence time of 1.8 hours. Dehydrated normal hexane 80 L / hour as a solvent, the above supported metallocene catalyst [Ia] as a catalyst was supplied at 1.4 mmol / hour in terms of Ti atom, and triisobutylaluminum was fed at 20 mmol / hour. In addition, hydrogen for molecular weight adjustment is supplied to 0.27 mol% with respect to the gas phase concentration of ethylene and 1-butene, and 1-butene is supplied to 0.57 mol% with respect to the gas phase concentration of ethylene. Ethylene and 1-butene were copolymerized. The catalyst was supplied from near the liquid level of the polymerization vessel, and ethylene and 1-butene were supplied from the bottom of the polymerization vessel. The polymerization slurry in the polymerization reactor was led to a flash tank having a pressure of 0.05 MPa and a temperature of 70 ° C. so that the level of the polymerization reactor was kept constant, and unreacted ethylene, 1-butene and hydrogen were separated.

  Next, it was led to a buffer tank having a pressure of 0.30 MPa and a temperature of 70 ° C. under an average residence time of 1.0 hour, and then continuously sent to a centrifuge to separate a polymer from other solvents. The separated ethylene-α-olefin copolymer powder was dried while blowing nitrogen at 85 ° C.

  Then, the obtained ethylene-α-olefin copolymer powder was an extruder in which two twin-screw extruders were connected in series (first stage: L / D = 7, second stage; L / D = 14, L: distance from raw material supply port to discharge port (m) of extruder, D: inner diameter (m) of extruder). At that time, in the first stage, the resin temperature in the extruder is 150 ° C., and pentaerythryl-tetrakis [3- (3,5-di-) as an antioxidant against the ethylene-α-olefin copolymer powder. t-butyl-4-hydroxyphenyl) propionate] is added to 200 ppm by mass, and the second stage is melt-kneaded and granulated so that the resin temperature in the extruder is 200 ° C. to obtain pellets. It was. Table 1 shows the measurement results of MFR, crystallization start temperature (Cp Onset), 1/2 isothermal crystallization time, density, molecular weight distribution, and short chain branching distribution of the obtained ethylene-α-olefin copolymer pellets.

  To 100 parts by mass of the obtained pellets, 0.025 part by mass of dicumyl peroxide and 1.5 parts by mass of vinyltrimethoxysilane were blended, and TEX-44 (L / D = 35) manufactured by Japan Steel Works. Was melt-kneaded at a resin temperature of 200 ° C. to obtain a silane graft-modified polyethylene resin composition.

  To the obtained silane-grafted modified polyethylene resin composition, 0.03 parts by mass of dioctyltin dilaurate was blended with 100 parts by mass of the pellets, and a pipe having a nominal diameter of 13 was formed by an extruder. This pipe was immersed in 90 ° C. hot water for 9 hours to be crosslinked to obtain a silane-crosslinked polyethylene pipe. The evaluation results of the silane-crosslinked polyethylene pipe are shown in Table 1.

[Example 2]
An ethylene-α-olefin copolymer was prepared in the same manner as in Example 1 except that the conditions of the twin screw extruder were set so that the resin temperature of the first stage was 200 ° C. and the second stage was 150 ° C. Pellets and silane cross-linked polyethylene pipes were obtained. The evaluation results are shown in Table 1.

[Example 3]
An ethylene-α-olefin copolymer pellet and a silane-crosslinked polyethylene pipe were obtained in the same manner as in Example 1 except that calcium stearate was fed as a lubricant to 300 ppm in the first stage of the extruder. The evaluation results are shown in Table 1.

[Example 4]
An ethylene-α-olefin copolymer was prepared in the same manner as in Example 3 except that the conditions of the twin screw extruder were set such that the first stage was 200 ° C. and the second stage was a resin temperature of 150 ° C. Pellets and silane cross-linked polyethylene pipes were obtained. The evaluation results are shown in Table 1.

[Example 5]
Using the above supported metallocene catalyst [Ib] under the conditions of a polymerization temperature of 80 ° C. and a polymerization pressure of 0.96 MPa, hydrogen is 0.31 mol% with respect to the gas phase concentration of ethylene and 1-butene, -By the same operation as in Example 1, except that butene was fed at 0.30 mol% with respect to the gas phase concentration of ethylene and calcium stearate was fed at 1500 ppm as a lubricant in the first stage of the extruder, ethylene-α -Olefin copolymer pellets and silane-crosslinked polyethylene pipes were obtained. The evaluation results are shown in Table 1.

[Example 6]
An ethylene-α-olefin copolymer was prepared in the same manner as in Example 5 except that the conditions of the twin screw extruder were set so that the resin temperature of the first stage was 200 ° C. and the second stage was 150 ° C. Pellets and silane cross-linked polyethylene pipes were obtained. The evaluation results are shown in Table 1.

[Example 7]
Using the above Ziegler-Natta catalyst [II] under conditions of a polymerization temperature of 85 ° C. and a polymerization pressure of 0.98 MPa, hydrogen is 44 mol% with respect to the gas phase concentration of ethylene and 1-butene, and 1-butene is ethylene. 8.0 mol% with respect to the gas phase concentration of 1, stearic acid 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as the antioxidant in the first stage of the extruder, 1500 ppm calcium stearate The ethylene-α-olefin copolymer pellets and the silane-crosslinked polyethylene pipe were obtained in the same manner as in Example 1 except that was fed to 500 ppm. The evaluation results are shown in Table 1.

[Example 8]
An ethylene-α-olefin copolymer was prepared in the same manner as in Example 7 except that the conditions of the twin screw extruder were set so that the resin temperature of the first stage was 200 ° C. and the second stage was 150 ° C. Pellets and silane cross-linked polyethylene pipes were obtained. The evaluation results are shown in Table 1.

[Example 9]
Using the above Ziegler-Natta catalyst [II] under the conditions of a polymerization temperature of 86 ° C. and a polymerization pressure of 1.0 MPa, hydrogen is 28 mol% with respect to the vapor phase concentration of ethylene and propylene, and propylene is the vapor phase concentration of ethylene. 3.5 mol%, and in the first stage of the extruder, calcium stearate is 2800 ppm, and as an antioxidant, stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate is 2500 ppm. An ethylene-α-olefin copolymer pellet and a silane-crosslinked polyethylene pipe were obtained in the same manner as in Example 1 except that the feed was performed as described above. The evaluation results are shown in Table 1.

[Example 10]
An ethylene-α-olefin copolymer was prepared in the same manner as in Example 9, except that the conditions of the twin screw extruder were set so that the resin temperature of the first stage was 200 ° C. and the second stage was 150 ° C. And a silane cross-linked polyethylene pipe was obtained. The evaluation results are shown in Table 1.

[Comparative Example 1]
Except for melt-kneading and granulating at a resin temperature of 200 ° C. with a twin screw extruder of TEX-44 (L / D = 35) manufactured by Nippon Steel Works, ethylene was obtained by the same operation as in Example 1. An α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. It took 130 minutes to obtain a sample with a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took longer for the crosslinking reaction to proceed than in Examples 1 and 2. Further, the gel fraction after 9 hours was 80%, which was lower than in Examples 1 and 2.

[Comparative Example 2]
Except for melt-kneading and granulating at a resin temperature of 200 ° C. with a twin screw extruder of TEX-44 (L / D = 35) manufactured by Nippon Steel Works, ethylene was made in the same manner as in Example 3. An α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. It took 150 minutes to obtain a sample having a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took longer for the crosslinking reaction to proceed than in Examples 3 and 4. Further, the gel fraction after 9 hours was 74%, which was lower than in Examples 3 and 4.

[Comparative Example 3]
Except for melt-kneading and granulating at a resin temperature of 200 ° C. with a twin screw extruder of Nippon Steel Works TEX-44 (L / D = 35), An α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. It took 140 minutes to obtain a sample having a gel fraction exceeding 65% in the crosslinking reaction at 95 ° C., and it took longer for the crosslinking reaction to proceed than in Examples 5 and 6. Further, the gel fraction after 9 hours was 69%, which was lower than in Examples 5 and 6.

[Comparative Example 4]
Except for melt-kneading and granulating at a resin temperature of 200 ° C. with a twin screw extruder of TEX-44 (L / D = 35) manufactured by Nippon Steel Works, ethylene was made in the same manner as in Example 7. An α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. It took 180 minutes to obtain a sample having a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took longer for the crosslinking reaction to proceed than in Examples 7 and 8. Further, the gel fraction after 9 hours was 68%, which was lower than in Examples 7 and 8.

[Comparative Example 5]
Except for melt-kneading and granulating at a resin temperature of 200 ° C. with a twin screw extruder of TEX-44 (L / D = 35) manufactured by Nippon Steel Works, ethylene was made in the same manner as in Example 9. An α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. It took 200 minutes to obtain a sample having a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took longer for the crosslinking reaction to proceed than in Examples 9 and 10. Further, the gel fraction after 9 hours was 65%, which was lower than in Examples 9 and 10, and the inner surface was not smooth and the appearance was deteriorated.

[Comparative Example 6]
Using the above Ziegler-Natta catalyst [II] under the conditions of a polymerization temperature of 86 ° C. and a polymerization pressure of 1.0 MPa, hydrogen is 53 mol% with respect to the vapor phase concentrations of ethylene and propylene, and propylene is the vapor phase concentration of ethylene. The amount of calcium stearate was 800 ppm and the amount of stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate was 250 ppm in the first stage of the extruder. Except for the above, an ethylene-α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained in the same manner as in Example 1. The evaluation results are shown in Table 2. It took 160 minutes to obtain a sample having a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took time for the crosslinking reaction to proceed. The gel fraction after 9 hours was 65%.

[Comparative Example 7]
An ethylene-α-olefin copolymer was prepared in the same manner as in Example 11 except that the conditions of the twin screw extruder were set so that the resin temperature of the first stage was 200 ° C. and the second stage was 150 ° C. And a silane cross-linked polyethylene pipe was obtained. The evaluation results are shown in Table 2. It took 140 minutes to obtain a sample having a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took time for the crosslinking reaction to proceed. The gel fraction after 9 hours was 67%.

[Comparative Example 8]
In the same manner as in Comparative Example 6 except that it was melt-kneaded and granulated at a resin temperature of 200 ° C. with a twin screw extruder of TEX-44 (L / D = 35) manufactured by Nippon Steel Co., Ltd. An α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. A sample having a gel fraction exceeding 65% in the crosslinking reaction at 95 ° C. was not obtained within 200 minutes, and it took time for the crosslinking reaction to proceed. Further, the gel fraction after 9 hours was 60%, there were further scratches on the surface, regular stripes were present on the inner surface, and the appearance was not smooth and deteriorated.

[Comparative Example 9]
Except that the buffer tank was not used, it was melt-kneaded and granulated at a resin temperature of 200 ° C. with a twin screw extruder of TEX-44 (L / D = 35) manufactured by Nippon Steel Co., Ltd. In the same manner as in Example 3, an ethylene-α-olefin copolymer and a silane-crosslinked polyethylene pipe were obtained. The evaluation results are shown in Table 2. It took 160 minutes to obtain a sample having a gel fraction exceeding 65% by the crosslinking reaction at 95 ° C., and it took time for the crosslinking reaction to proceed. Further, the gel fraction after 9 hours was 75%, but the color of the pipe was yellowish.

  By using the ethylene-α-olefin copolymer of the present invention, a silane-crosslinked polyethylene pipe having a high crosslinking rate and a high gel fraction can be produced. Thereby, the bottleneck of the molding cycle of a silane crosslinked polyethylene pipe can be improved. Therefore, the present invention has high industrial applicability.

Claims (9)

A copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms,
The melt flow rate at 190 ° C. and 2.16 kg is 1.0 g / 10 min or more and 10 g / 10 min or less,
The peak top time (1/2 isothermal crystallization time) in isothermal crystallization at + 5 ° C. is 300 seconds or more with respect to the crystallization start temperature (Cp Onset) determined by the differential scanning calorimeter (DSC) method. is there,
Ethylene-α-olefin copolymer. Density is 930 kg / m ³ or more 950 kg / m ³ or less,
The ethylene-α-olefin copolymer according to claim 1. The molecular weight distribution based on the weight average molecular weight and the number average molecular weight determined from gel permeation chromatography is 2.5 or more and 5.0 or less,
The short chain branching distribution obtained from gel permeation chromatography and FT-IR and represented by the following formula (A) is 0.1 or more and 2.0 or less.
The ethylene-α-olefin copolymer according to claim 1 or 2.
Short chain branch distribution = (number of short chain branches per 1000 carbons when log M is 5.0) − (number of short chain branches per 1000 carbons when log M is 4.0) (A)
(In formula (A), M represents the molecular weight in gel permeation chromatography, and log M represents the logarithm of M with 10 as the base.) The ethylene-α-olefin copolymer according to any one of claims 1 to 3 and an antioxidant,
The content of the substance functioning as the antioxidant is 200 mass ppm or less,
Resin composition. The ethylene-α-olefin copolymer according to any one of claims 1 to 3 is continuously passed through an extruder at least twice, kneaded and granulated to obtain the resin composition according to claim 4. Having a grain process,
A method for producing a resin composition. The relationship between the resin temperature T1 in the first stage extruder and the resin temperature T2 in the second stage extruder is T1 <T2.
The manufacturing method of the resin composition of Claim 5. The ethylene-α-olefin according to any one of claims 1 to 3, wherein ethylene and an α-olefin having 3 to 8 carbon atoms are copolymerized in the presence of a supported geometrically constrained metallocene catalyst. Having a polymerization step to obtain a copolymer;
A method for producing an ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer according to any one of claims 1 to 3 and 100 parts by mass of the ethylene-α-olefin copolymer are 0.025 parts by mass or more and 1.0 part by mass. Including the following organic peroxide and 0.1 to 1.5 parts by mass of an organic unsaturated silane compound:
Silane graft-modified polyethylene resin composition. The crosslinked product of the silane graft-modified polyethylene resin composition according to claim 8,
Silane cross-linked polyethylene pipe.