JP2003321519A - ETHYLENE/alpha-OLEFIN COPOLYMER - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new ethylene/α-olefin copolymer good in balance among rigidity, molding processability and long-term creep tendency. <P>SOLUTION: The new ethylene/α-olefin copolymer is made from ethylene and a 3-20C α-olefin, meeting the following requirements: (1) MFR is 0.01-20 g/10 min, (2) density is 0.910-0.960 g/cm<SP>3</SP>, and (3) meeting the relationship: logN≥17.0Pc-1.00 (wherein, N is the repeating frequency until rupture when measured at 80°C under applied stress of 6 MPa in a repeating tensile fatigue test, and Pc is the ratio of the amount of elution corresponding to the critical molecular weight (Mc) or greater enabling tie molecule formation to the total amount of elution in the relationship between molecular weight and the amount of elusion obtained by gel permeation chromatography (GPC) and Mc is calculated based on the density and the melting point). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ethylene / α-olefin copolymer excellent in long-term creep property. More specifically, the present invention relates to an ethylene / α-olefin copolymer having an excellent balance of rigidity and long-term creep property and excellent moldability.

[0002]

2. Description of the Related Art Polyethylene resin has rigidity, impact resistance,
It has excellent mechanical properties such as ESCR and elongation properties, and also has excellent chemical resistance, corrosion resistance and electrical properties, so it is widely used in the fields of injection molded products, films, sheets, pipes, blow containers, etc. There is.

However, recently, from the viewpoint of consideration for environmental problems and easiness of handling, there is a strong demand for thinner and lighter products, and sufficient strength can be obtained even if the wall thickness is thin, and ES
A polyethylene resin having excellent long-term creep property such as CR is desired. Further, from the viewpoint of product productivity, there is a demand for a polyethylene resin which has a small load during molding and can increase the production rate, and has excellent moldability with less appearance defects.

Generally, in order to reduce the wall thickness and maintain the strength of the product, it is necessary to increase the rigidity (that is, the density of polyethylene), but the long-term creep property has a contradictory relationship with the density, and thus the thin wall When the density of polyethylene is increased in order to cope with the increase in the tendency to occur, there arises a problem that the long-term creep property such as ESCR is insufficient. Further, in order to improve the moldability, it is basically necessary to reduce the molecular weight,
Also in this case, the long-term creep property is deteriorated. Therefore, it has been difficult to obtain a polyethylene resin satisfying all of rigidity, moldability and long-term creep property by the conventional technique.

In recent years, a polyethylene resin having an improved balance of rigidity, moldability and long-term creep property has been developed by separately manufacturing a low molecular weight component and a high molecular weight component and introducing a comonomer only into the high molecular weight component. ing. However, even when such a device is applied, long-term creep properties such as ESCR are insufficient in applications requiring high rigidity, and molding processability is reduced by increasing the molecular weight to improve long-term creep properties. The problem still exists.

[0006]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides rigidity, moldability,
New ethylene / with excellent balance of long-term creep property
An object is to provide an α-olefin copolymer.

[0007]

As a result of earnest studies, the inventors of the present invention have found that the long-term creep property of an ethylene / α-olefin copolymer having a molecular weight distribution consisting essentially of one component is It was found that a component having a molecular weight equal to or higher than the critical molecular weight (Mc) capable of forming a tie molecule calculated from the density and melting point of the / α-olefin copolymer depends on the ratio of the total molecular weight component.

Further, according to the present invention, an ethylene / α-olefin copolymer polymerized by using a specific Ziegler-Natta catalyst is conventionally used even if the ratio of the molecular weight component capable of forming the tie molecule is the same. It was found that the long-term creep property is superior to that of the above resin, and the present invention has been completed.

That is, according to the present invention, (1) MFR is 0.0
1 to 20 g / 10 min, and (2) density is 0.91
0 to 0.960 g / cm ³ , and (3) repeated tensile fatigue test, measured temperature 80 ° C, applied stress 6 MPa
Number of repetitions (N) until breakage when measured at
And gel permeation chromatography (G
PC) In the relationship of molecular weight-elution amount obtained by measurement, the ratio (Pc) of the elution amount above the critical molecular weight (Mc) capable of forming tie molecules calculated from the density and melting point (Pc)
Satisfies log N ≧ 17.0 Pc−1.00 Pc = (elution amount above the critical molecular weight (Mc) capable of forming Thai molecules) / total elution amount, ethylene / α-olefin copolymerization Further, it is a coalesced product, and further, the ratio (Pc) of the elution amount of the critical molecular weight (Mc) or more capable of forming the tie molecule and the total elution amount is 0.150 or more, which is excellent in long-term creep property. The ethylene / α-olefin copolymer, which is an ethylene / α-olefin copolymer, can be obtained by slurry polymerization using a specific Ziegler-Natta catalyst.

The present invention will be described in detail below. Examples of the α-olefin having 3 to 20 carbon atoms used for the ethylene / α-olefin copolymer in the present invention include propylene and
1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like can be mentioned, and these can be used alone or in combination of two or more kinds. Of these α-olefins, 1-butene, 1-
Penten, 1-hexene and 1-octene are particularly preferred.

The content of the α-olefin having 3 to 20 carbon atoms contained in the ethylene / α-olefin copolymer is
It is preferably 8 wt% or less.

MF of ethylene / α-olefin copolymer
R is in the range of 0.01 to 20 g / 10 min. M
If the FR is less than 0.01 g / 10 min, the fluidity at the time of molding is lowered, and unmelted gel is likely to be generated. On the other hand, if the MFR is more than 20 g / 10 min, the mechanical strength is lowered and excellent. The long-term creep property cannot be obtained. The preferred range of MFR of the ethylene / α-olefin copolymer is 0.03 to 10 g / 10 mi.
n, and more preferably 0.05 to 5 g / 10 mi
n.

The density of the ethylene / α-olefin copolymer needs to be in the range of 0.910 to 0.960 g / cm ³ . If the density is less than 0.910 g / cm ^3, the highly rigid ethylene / α-olefin copolymer, which is the object of the present invention, cannot be obtained. On the other hand, the density is 0.96
If it exceeds 0 g / cm ³ , long-term creep properties will be insufficient. The density range of the ethylene / α-olefin copolymer is preferably 0.915 to 0.955 g / cm ³ , and more preferably 0.920 to 0.950 g / cm 3.
^{Is 3} .

The ethylene / α-olefin copolymer according to the present invention is a Ziegler-prepared from a homogeneous solution obtained from metallic magnesium, alcohol, titanium alkoxide, an oxygen-containing organic compound and an organoaluminum halide described below. It can be produced by a slurry polymerization method using a Natta catalyst.

The ethylene / α-olefin copolymer of the present invention is subjected to repeated tensile fatigue tests at a measurement temperature of 80.
Calculated from the density and the melting point in the relationship between the number of repetitions (N) until breakage when measured at ℃ and an applied stress of 6 MPa and the molecular weight-elution amount obtained by gel permeation chromatography (GPC) measurement. The ratio (Pc) of the elution amount above the critical molecular weight (Mc) capable of forming a Thai molecule and the total elution amount is logN ≧ 17.0Pc-1.00 Pc = (Critical molecular weight (Mc) above which the Thai molecule can be formed) It is necessary to satisfy the relationship of (elution amount) / total elution amount.

Here, the number of repetitions (N) until the fracture by the repeated tensile fatigue test is applied to the test piece notched all around under the temperature condition of 80 ° C. by the test method shown in the example. It can be obtained by repeatedly applying a load with a rectangular wave having a stress of 6 MPa and a frequency of 0.5 Hz.

The ratio (Pc) of the elution amount above the critical molecular weight (Mc) capable of forming the tie molecule to the total elution amount.
Is GP of the ethylene / α-olefin copolymer of the present invention.
In the relationship of molecular weight-elution amount obtained by C measurement,
It can be calculated from the ratio of the elution area of Mc or more to the total elution area. Here, the critical molecular weight (Mc) that the tie molecule can form is as described in J. Polym. Sci. , Polym.
Phys. Ed. , 29 , 129 (1991), with reference to the concept of tie molecule formation, and was calculated by the following method. The details will be described below. Thai molecule is
Spreading of molecular chains in the molten state (average distance between molecular ends:
r) is a critical thickness (2) of crystalline or amorphous solid state.
Since it is formed when it is larger than Lc + La), the critical condition for forming a tie molecule can be expressed by the following formula (I).

R = (2Lc + La) (I) (In the formula, Lc is the crystal thickness and La is the amorphous thickness.) In the case of polyethylene, r is the following formula (II) between r and the molecular weight (M). Have a relationship.

R = 1.066M ^0.5 (II) When the formula (II) is substituted into the formula (I), the formula (III) is obtained, and the values of Lc and La are calculated to obtain the formula (II).
From I), the critical molecular weight (Mc) that the tie molecule can form can be calculated.

Mc = 0.88 (2Lc + La) ² (III) Lc is ethylene / α determined by DSC measurement.
From the melting point (Tm) of the olefin copolymer to the following formula (IV)
Can be calculated by

Lc = (6.26 × 414) / (414-Tm) (IV) (where the unit of Tm is [K].) La is calculated from the following formula (Lc) and crystallinity (Xc). It can be calculated by V).

La = (Lc (1-Xc)) / Xc (V) Xc can be calculated by the following formula (VI) from the density (d) of the ethylene / α-olefin copolymer measured by a density gradient tube.

Xc = (d−0.86) /0.14d (VI) The ethylene / α-olefin copolymer of the present invention has a logarithm (logN) of the number of repetitions until the fracture by the repeated tensile fatigue test. It is 17.0Pc-1.00 or more, preferably 17.0Pc-0.80 or more, and more preferably 17.0Pc-0.60 or more. The value is 17.0
When it is less than Pc-1.00, the long-term creep property is insufficient, and an ethylene / α-olefin copolymer having a high level of rigidity, moldability and long-term creep property cannot be obtained.

The ethylene / α-olefin copolymer of the present invention has a critical molecular weight (M
The ratio (Pc) of the above-mentioned elution amount and the total elution amount is 0.150.
Or more, preferably 0.200 or more, more preferably 0.225 or more. When Pc is less than 0.150, the number of repetitions until the fracture by the repeated tensile fatigue test is too small and the error becomes large, and the long-term creep property intended by the present invention becomes insufficient.

Next, the catalyst and the production method for obtaining the ethylene / α-olefin copolymer of the present invention will be described. The ethylene / α-olefin copolymer in the present invention is a Ziegler-Natta catalyst prepared by using as raw materials a homogeneous solution obtained from metallic magnesium, alcohol, titanium alkoxide, an oxygen-containing organic compound and an organoaluminum halide described below. It can be produced by a slurry polymerization method.

Here, the Ziegler-Natta catalyst, which is preferably used in the present invention, prepared by using as raw materials a homogeneous solution obtained from metallic magnesium, alcohol, titanium alkoxide, an organic compound containing oxygen and an organoaluminum halide is prepared. An example will be described.

The following are examples of magnesium metal and alcohol used for preparing the Ziegler-Natta catalyst of the present invention.

First, as the metallic magnesium, various shapes can be used, that is, any shape such as powder, particles, foil or ribbon can be used.

As the alcohol, a linear or branched aliphatic alcohol having 1 to 18 carbon atoms or an alicyclic alcohol having 3 to 18 carbon atoms can be used. Examples include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-.
Hexanol, 2-ethylhexanol, n-octanol, isooctanol, n-stearyl alcohol,
Examples include cyclopentanol, cyclohexanol, ethylene glycol and the like.

These alcohols are used alone or as a mixture of two or more kinds. Of course, it may be used alone, but when it is used as a mixture of two or more kinds, it may exert a peculiar effect on the powder characteristics of the polymer.

In addition, when using magnesium metal to obtain the homogeneous solution described in the present invention, for the purpose of accelerating the reaction, a substance which reacts with metal magnesium or forms an addition compound, such as iodine. It is preferable to add polar substances such as mercuric chloride, alkyl halides, organic acid esters and organic acids, either alone or in combination of two or more.

As the titanium alkoxide, a compound represented by the general formula [TiO _a (OR ¹ ) _b ] _m is preferably used. However, in the general formula, R ¹ has 1 to ¹ carbon atoms.
20, preferably a hydrocarbon group such as a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an arylalkyl group, an aryl group and an alkylaryl group, wherein a and b are a When ≧ 0, b> 0 represents a number compatible with the valence of titanium, and m represents an integer. In particular, it is desirable to use titanium alkoxide in which a is 0 ≦ a ≦ 1 and m is 1 ≦ m ≦ 6.

Specific examples include titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, and hexaisopropoxy dititanate. The use of titanium alkoxide having several different hydrocarbon groups is also within the scope of the invention. These titanium alkoxides are used alone or as a mixture of two or more kinds.

As the oxygen-containing organic compound, ethers, esters, ketones, acid anhydrides and silicic acid esters are used.

As the ethers, diethyl ether,
Dibutyl ether, diamyl ether, methyl phenyl ether, diphenyl ether, tetrahydrofuran, dioxane, dimethoxyethane, dimethoxypropane, dimethoxybutane, diethoxyethane, diethoxypropane, diethoxybutane, dimethoxytetrahydrofuran, dimethyldimethoxypropane, diethyldimethoxypropane, dibutyl Examples thereof include dimethoxypropane, ethylbutyldimethoxypropane and polyethylene methyl ether.

Examples of the esters include ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, butyl propionate, methyl benzoate, ethyl benzoate, methyl toluate, ethyl toluate, methyl anisate and ethyl anisate. can give.

As the ketones, acetone, ethyl methyl ketone, cyclobutanone, cyclopentanone, cyclohexanone, acetophenone, propiophenone, benzophenone, dibenzyl ketone, diacetyl, acetylbenzoyl, benzyl, acetylacetone, benzoylacetone, dibenzoylmethane, Examples include acetonylacetone.

Examples of the acid anhydride include succinic acid, glutaric acid and phthalic acid.

Specific examples of the silicic acid ester include hexamethyldisiloxane, octamethyltrisiloxane, dimethylpolysiloxane, diethylpolysiloxane, methylethylpolysiloxane, methylhydropolysiloxane, ethylhydropolysiloxane, butylhydro. Polysiloxane, hexaphenyldisiloxane, octaphenyltrisiloxane, diphenylpolysiloxane, phenylhydropolysiloxane, methylphenylpolysiloxane, 1,5-dichlorohexamethyltrisiloxane, 1,7-dichlorooctamethyltetrasiloxane, dimethoxypolysiloxane , Diethoxypolysiloxane, diphenoxypolysiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclo Penta siloxane, 2,4,6
Polysiloxanes such as trimethylcyclotrisiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, triphenyltrimethylcyclotrisiloxane, tetraphenyltetramethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, octaphenylcyclotetrasiloxane Can be given. Also, for example, trimethylmethoxysilane, dimethyldiethoxysilane,
Alkoxysilanes such as methyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, diphenyldiethoxysilane, tetramethyldiethoxydisilane and dimethyltetraethoxydisilane, haloalkoxy such as dichlorodiethoxysilane, dichlorodiphenylsilane and tribromoethoxysilane. And silane compounds containing a fatty acid residue such as phenoxysilane, trimethylacetoxysilane, diethyldiacetoxysilane, and ethyltriacetoxysilane. Of these, chain polysiloxanes such as dimethylpolysiloxane and methylhydropolysiloxane, methyltrimethoxysilane,
Alkoxysilanes such as tetramethoxysilane and tetraethoxysilane are preferably used.

The elution ratio to the solvent during the polymerization reaction is small,
Diethers, polyethers, esters, diketones, and alkoxysilanes containing a plurality of oxygen atoms are preferable for the reason that the change of the catalyst with time is small. Particularly preferred are diethers, polyethers and alkoxysilanes.

The above oxygen-containing organic compounds may be used alone, or two or more kinds may be mixed or reacted and used.

As the halogenated organoaluminum compound, those represented by the general formula R ² _z AlX _3-z are used. However, in the general formula, R ² has 1 to ² carbon atoms.
Represents a hydrocarbon group having 0, preferably 1 to 8 carbon atoms,
X represents a halogen atom, and z represents a number of 0 <z <3, preferably 0 <z ≦ 2. Further, R ² is preferably selected from a linear or branched alkyl group, a cycloalkyl group, an arylalkyl group, an aryl group and an alkylaryl group.

Specific examples of the organoaluminum halide compound include, for example, dimethyl aluminum chloride,
Examples thereof include diethyl aluminum chloride, diethyl aluminum bromide, dipropyl aluminum chloride, ethyl aluminum dichloride, isobutyl aluminum dichloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, isobutyl aluminum sesquichloride, and a mixture of triethyl aluminum and aluminum trichloride.

The above organoaluminum halide compounds can be used alone or as a mixture of two or more kinds. In order to improve the powder property, it is preferable to use a mixture of two or more kinds.

When the Ziegler-Natta catalyst of the present invention is prepared, an oxygen-containing silicon compound can be used for the purpose of controlling the particle shape of the catalyst and improving the catalytic activity.

As the oxygen-containing silicon compound, polysiloxanes and silanes are used. Among them, the polysiloxane includes chain polysiloxane and cyclic polysiloxane.

Specific examples of the chain polysiloxane include hexamethyldisiloxane, octamethyltrisiloxane, dimethylpolysiloxane, diethylpolysiloxane, methylethylpolysiloxane, methylhydropolysiloxane, ethylhydropolysiloxane and butyl. Hydropolysiloxane, hexaphenyldisiloxane, octaphenyltrisiloxane, diphenylpolysiloxane, phenylhydropolysiloxane, methylphenylpolysiloxane, 1,5-dichlorohexamethyltrisiloxane, 1,7-dichlorooctamethyltetrasiloxane, dimethoxypolysiloxane Examples thereof include siloxane, diethoxypolysiloxane, diphenoxypolysiloxane and the like.

As the cyclic polysiloxane, for example, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, 2,4,6-trimethylcyclotrisiloxane,
Examples include 2,4,6,8-tetramethylcyclotetrasiloxane, triphenyltrimethylcyclotrisiloxane, tetraphenyltetramethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, octaphenylcyclotetrasiloxane.

Further, as the polysiloxane having a three-dimensional structure, for example, the above-mentioned chain or cyclic polysiloxane having a crosslinked structure by heating or the like can be mentioned.

It is desirable that these polysiloxanes are liquid for handling, and the viscosity at 25 ° C. is 1 to 1000.
It is desirable that the range is 0 centistokes, more preferably 1 to 1000 centistokes. However, it is not necessary to limit it to a liquid state, and a solid substance generally referred to as silicon grease may be used.

On the other hand, specific examples of silanes include trimethylmethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, diphenyldiethoxysilane, tetramethyldiethoxydisilane and dimethyltetrasilane. Alkoxysilanes such as ethoxydisilane, dichlorodiethoxysilane, dichlorodiphenylsilane, haloalkoxy such as tribromoethoxysilane and silane compounds containing fatty acid residues such as phenoxysilane, trimethylacetoxysilane, diethyldiacetoxysilane, ethyltriacetoxysilane. And so on. Of these, chain polysiloxanes such as dimethylpolysiloxane and methylhydropolysiloxane, and alkoxysilanes such as methyltrimethoxysilane, tetramethoxysilane, and tetraethoxysilane are preferably used.

The above silicon compounds may be used alone, or two or more kinds may be mixed or reacted and used.

The reaction sequence of metallic magnesium, alcohol and titanium alkoxide in producing the homogeneous solution of the present invention may be any order as long as it causes a chemical reaction. For example, a method of adding an alcohol to a mixture of metal magnesium and titanium alkoxide, a metal magnesium, an oxygen-containing organic compound, a method of adding alcohol in the presence of titanium alkoxide, a metal magnesium, an oxygen-containing organic compound to a mixture of alcohol, titanium Examples thereof include a method of adding alkoxide, a method of adding titanium alkoxide to a mixture of metallic magnesium, alcohol and an oxygen-containing organic compound. The above-mentioned homogeneous solution can be obtained by such a method.

Here, the reaction between the homogeneous solution and the organoaluminum halide is preferably carried out in a liquid medium. As the solvent, any of those commonly used in the art can be used, and examples thereof include aliphatic, alicyclic or aromatic hydrocarbons, halogen derivatives thereof, or a mixture thereof, such as isobutane and hexane. , Heptane, cyclohexane, benzene, toluene, xylene, monochlorobenzene and the like are preferably used.

The amount of magnesium, alcohol or titanium alkoxide used in the present invention is 0.2 ≦ Mg in terms of the atomic ratio of the gram atom of metallic magnesium (Mg) to the gram atom of Ti of the titanium alkoxide. / Ti ≦
100, preferably 1 ≦ Mg / Ti ≦ 30, particularly preferably 4 <Mg / Ti ≦ 20. Mg / Ti is 100
If it exceeds the above range, it may be difficult to obtain a uniform solution during the preparation of the catalyst, or the activity of the catalyst may decrease during the polymerization. On the other hand, if it is less than 0.2, the activity of the catalyst tends to be low, which may cause a problem such as coloring of the product.

The molar ratio of the oxygen-containing organic compound to the Mg is 0.05 ≦ Mg / oxygen-containing organic compound ≦ 100,
It is preferable to select the amount used so that 0.1 ≦ Mg / oxygen-containing organic compound ≦ 10. Mg /
If the oxygen-containing organic compound exceeds 100, the powder characteristics may not be sufficiently improved. On the other hand, if it is less than 0.05, the activity of the catalyst may decrease.

The molar ratio of Si to Mg in the silicon compound used as required is 0.05 ≦ Mg / S.
It is preferable to select the amount used so that i ≦ 100, preferably 0.5 ≦ Mg / Si ≦ 10. Mg / S
If i exceeds 100, the powder characteristics may not be sufficiently improved. On the other hand, if it is less than 0.05, the activity of the catalyst may decrease.

When the homogeneous solution of the present invention is reacted with the organoaluminum halide, the type and amount of the organoaluminum halide are appropriately selected, and solid particles are deposited from the homogeneous solution. In particular, it is necessary to appropriately control the crystal nuclei formed in the initial stage of the reaction. Therefore, the reaction of the homogeneous solution and the organoaluminum halide compound is preferably carried out in two steps. When the reaction is performed in two stages, the precipitation reaction of the solid particles to be the crystal nuclei is performed in the first stage, and the growth reaction of the crystal nuclei deposited in the first stage is performed in the second stage.
For this purpose, it is necessary to make the type and amount of the organoaluminum halide compound used in the first and second stages suitable for each stage. More specifically,
In the first-stage reaction, Z of the halogenated organoaluminum compound R ² _z AlX _3-z is 1 ≦ Z ≦ 2, the amount (molar ratio) to Mg is 0.5 to 2.0, and in the second-stage reaction, each is 0. <Z <2, and the usage amount (molar ratio) with respect to Mg is 1.
It is preferably 0 to 20.

The reaction conditions in each step are not particularly limited, but are inert for 0.5 to 50 hours, preferably 1 to 6 hours at a temperature in the range of -50 to 300 ° C, preferably 0 to 200 ° C. It is carried out under normal pressure or under pressure in a gas atmosphere.

The reaction of the first and second steps may be carried out continuously,
It is also possible to carry out an aging reaction to complete the precipitation of crystals after the reaction of the former stage by dividing. It is also possible to change the reaction conditions in the first and second stages, respectively. Preferably, an aging reaction is carried out between the first-stage reaction and the second-stage reaction.

The conditions of the aging reaction are not particularly limited, but the temperature is in the range of -50 to 300 ° C, preferably 0 to 200 ° C for 0.5 to 50 hours, preferably 1 to 6 hours.
It is carried out at normal pressure or under pressure in an inert gas atmosphere for a time.

The Ziegler-Natta catalyst thus obtained is
Without removing residual unreacted materials and by-products,
Alternatively, it can be used after being removed by filtration or a gradient method.

When carrying out the polymerization using the above Ziegler-Natta catalyst, an organoaluminum compound is usually used for the purpose of promoting the manifestation of catalytic activity. Preferred are organoaluminum compounds having a linear or branched alkyl group having 1 to 10 carbon atoms. In particular, use of trialkylaluminum having a linear or branched alkyl group having 1 to 10 carbon atoms is preferable. In particular,
Examples thereof include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-decylaluminum and the like.

Other examples of the organoaluminum compound include alkyl metal hydrides having an alkyl group having 1 to 10 carbon atoms. Specific examples of such a compound include diisobutylaluminum hydride. Further, an alkyl metal halide having an alkyl group having 1 to 20 carbon atoms such as ethyl aluminum sesquichloride, diethyl aluminum chloride, diisobutyl aluminum chloride or an alkyl metal alkoxide such as diethyl aluminum ethoxide can be used.

An organoaluminum compound obtained by reacting a trialkylaluminum or dialkylaluminum hydride having an alkyl group having 1 to 10 carbon atoms with a diolefin having 4 to 20 carbon atoms, for example, a compound such as isoprenylaluminum. Can also be used.

The above organoaluminum compounds may be used alone or in a mixture or reaction of two or more.

An electron donating compound may be used for the purpose of controlling the molecular weight, the molecular weight distribution and the composition distribution.

When an electron-donating compound is used, an ether compound, an organic acid ester, an oxygen-containing organic compound of silicon, a nitrogen-containing organic compound and the like are suitable as the compound. Specific examples thereof include dimethoxyethane, dimethoxypropane, dimethyldimethoxypropane, dibutyldimethoxypropane, ethyl benzoate, ethyl toluate, tetraethoxysilane, diphenyldimethoxysilane and diphenylamine.

The ethylene / α-olefin copolymer according to the present invention can be produced under the general reaction conditions of a slurry method using a so-called Ziegler-Natta catalyst. That is, 20 to 110 ° C. in a continuous system or a batch system
Polymerization is carried out at the temperature of. The polymerization pressure is not particularly limited, but it is suitable to use under pressure, particularly 0.15 to 5 MPa. As the solvent for carrying out the polymerization, any of the commonly used solvents can be used. Particularly, the number of carbon atoms is 3 to 20
Are suitable alkanes or cycloalkanes such as propane, isobutane, pentane, hexane, cyclohexane and the like.

Examples of the α-olefin used in the polymerization of the ethylene / α-olefin copolymer of the present invention include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene and the like. These can be used alone or in combination of two or more. Further, in order to introduce a double bond into the polymer,
The copolymerization can also be carried out using a mixture of α-olefin and a diene such as butadiene or isoprene. The amount of α-olefin used for copolymerization needs to be selected according to the density of the target polymer.

In carrying out the present invention, the amount of Ziegler-Natta catalyst used is 1 liter of solvent or 1 liter of reactor.
Therefore, it is preferable to use an amount corresponding to 0.001 to 2.5 mmol of titanium atom, and a higher concentration can be used depending on the conditions.

The organoaluminum compound is used in a concentration of 0.02 to 50 mmol, preferably 0.2 to 5 mmol, per liter of solvent or per liter of reactor.

The molecular weight of the ethylene / α-olefin copolymer produced in the present invention can be adjusted by a known means, that is, by allowing an appropriate amount of hydrogen to exist in the reaction system.

The ethylene / α-olefin copolymer of the present invention can be obtained by subjecting the obtained polymerized powder to melt kneading using a single-screw or multi-screw extruder, or known methods such as Banbury mixers, kneaders and rolls. A method of melt kneading using a kneading device can be used.

The ethylene / α-olefin copolymer of the present invention is an ethylene-based polymer obtained by a catalyst other than the catalyst used in the present invention and a production method, for example, an ethylene-α-olefin copolymer, such as Ziegler-Natta catalysts other than the catalyst used in the invention, single-site catalysts, ethylene-based polymers obtained by Phillips-type chromium-based catalysts, ethylene-based polymers obtained by the high-pressure radical method, etc. may also be blended and used. it can.

Further, the ethylene / α-olefin copolymer of the present invention may contain various additives as required, such as antioxidants, neutralizing agents, lubricants, weathering agents, antistatic agents, flame retardants,
Nucleating agent, cross-linking agent (peroxide, etc.), carbon black, various pigments and talc, calcium carbonate, clay, mica,
Various inorganic fillers such as barium sulfate and magnesium hydroxide, and conductive fillers such as metal fibers can be blended.

The ethylene / α-olefin copolymer obtained by the present invention is a known method conventionally used for molding polyethylene resins, for example, extrusion molding, blow molding, injection blow molding, injection molding, inflation molding. It can be molded by a method such as rotational molding or vacuum molding.

[0078]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Various measuring methods in Examples and Comparative Examples are shown below.

(1) Repeated Tensile Fatigue Test Product name Shimadzu Corporation Servo Pulsar EHF-E
Using D10 type, test temperature 80 ° C, applied stress 6 MPa
A load was repeatedly applied to the test piece with a rectangular wave having a frequency of 0.5 Hz (completely oscillated state), and the number of repetitions until the test piece was broken was measured. The measurement sample has a melting temperature of 19
Thickness 5 produced by compression molding at 0 ℃ and molding temperature 60 ℃
A dumbbell-shaped test piece with a marked line portion having a length of 20 mm and a width of 5 mm was punched from a flat plate having a depth of 0.
A 5 mm leather notch was used all around.

(2) GPC GPC measurement in the present invention is carried out under the following conditions. [Device] Tosoh Corp. HLC-8121GPC / H
T [Measurement condition] column: TSKgel GMHHR-H
(20) HT x 3, eluent: trichlorobenzene + antioxidant (BHT 0.05%), flow rate: 1.0 ml /
Min, sample concentration: 1.0 mg / ml, injection amount: 0.3 m
1, column temperature: 140 ° C., detector: HLC-8121
GPC / HT (3) Melting point [apparatus] Seiko Denshi Kogyo KK DSC200 type [measurement condition] About 5 mg of sample was precisely weighed and held at 230 ° C for 5 minutes, and then cooled to -10 ° C at 10 ° C / minute. After doing 10
The maximum value of the endothermic peak obtained when the temperature was raised at ° C / min was taken as the melting point.

(4) Using a MI hood with a density hood, the sample extruded under a load of 5 kg at 190 ° C. was gradually cooled in the hood for 5 minutes and then at 23 ° C.
The density gradient tube was used for the measurement.

(5) ESCR Based on JIS K 6760. As the test solution, a 10 wt% aqueous solution of Nonion NS-210 manufactured by NOF CORPORATION was used.

The method for preparing the catalysts used in the examples and comparative examples will be described below, but the present invention is not limited to these examples. Catalyst Preparation Example 1 shows a preparation example of a catalyst preferably used when polymerizing the ethylene / α-olefin copolymer of the present invention, and Catalyst Preparation Example 2 shows an ethylene / α-olefin copolymer used in Comparative Examples. An example of preparation of the catalyst used for the polymerization is shown.

Catalyst Preparation Example 1: Ziegler-Natta Catalyst (A) 385.5 g of 2-ethyl-1-hexanol was placed in a 10 l stainless steel autoclave equipped with a stirrer.
(2.96 mol) and n-butanol 219.4 g
(2.96 mol), 2.0 g of iodine, 60 g of metal magnesium powder (2.47 mol) and 166.8 g of titanium tetrabutoxide (0.49 mol) were added, and 2.0 l of hexane was further added. After that, the temperature is raised to 80 ° C and the generated hydrogen gas is eliminated, and the temperature is set to 1 under a nitrogen seal.
Stir for hours. Subsequently, the temperature was raised to 120 ° C. and the reaction was performed for 1 hour to obtain a uniform solution containing Mg and Ti. The homogeneous solution is cooled to 45 ° C and 1,2-dimethoxypropane is added.
51.0 g (0.49 mol) was added and the mixture was aged at 45 ° C for 1 hour. The internal temperature of the autoclave was maintained at 45 ° C., and 3063 g (9.88 mol) of a 50% hexane solution of isobutylaluminum dichloride was added over 2 hours. After all the ingredients were added, the mixture was stirred at 70 ° C. for 1 hour to give 35 parts of Ziegler-Natta catalyst (A) having a Ti content of 6.6 wt%.
5.6 g was obtained. The resulting catalyst (A) was used as hexane slurry in the next polymerization step after removing unreacted substances and by-products remaining with hexane.

Catalyst Preparation Example 2: Ziegler-Natta Catalyst (B) In a 10 l stainless steel autoclave equipped with a stirrer, 108.2 g (1.80 mol) of isopropanol and 134.6 g (1.82 mol) of n-butanol were added. , 2.0 g of iodine, 40 magnesium metal powder
g (1.65 mol) and titanium tetrabutoxide 2
24.1 g (0.66 mol) was added, 2.0 l of hexane was further added, the temperature was raised to 80 ° C, and the mixture was stirred for 1 hour under a nitrogen blanket while eliminating generated hydrogen gas. Subsequently, the temperature was raised to 120 ° C. and the reaction was carried out for 1 hour.
A homogeneous solution containing i was obtained. Set the internal temperature of the autoclave to 45
The temperature was maintained at 0 ° C., and 1.32 kg (3.3 mol) of a 30% hexane solution of diethylaluminum chloride was added over 1 hour. After adding all, it stirred at 60 degreeC for 1 hour.
After cooling to 45 ° C., 2.81 kg (9.1 mol) of a 50% hexane solution of isobutylaluminum dichloride was added to 2 parts.
Added over time. After adding all, stirring was carried out at 70 ° C. for 1 hour to obtain 287.4 g of Ziegler-Natta catalyst (B) having a Ti content of 11 wt%. The obtained catalyst (B) was used in the next polymerization step as a hexane slurry after removing the remaining unreacted substances and by-products using hexane.

Example 1 A stainless steel electromagnetic stirring type autoclave having an internal volume of 10 l was sufficiently replaced with nitrogen, and 6.0 l of hexane was charged, and the internal temperature was adjusted to 80 ° C. Then, a slurry containing 1.15 g (5.79 mmol) of triisobutylaluminum and 50 mg of the catalyst (A) obtained by the method of catalyst preparation example 1 was sequentially added. After adjusting the internal pressure of the autoclave to 0.1 MPa, add 0.4 MPa of hydrogen,
Then, 159 g of 1-butene was press-fitted with ethylene, and polymerization was carried out for 1.5 hours while continuously adding ethylene so that the internal pressure of the autoclave became 1.1 MPa. After the completion of polymerization, the reaction mixture was cooled, unreacted gas was expelled, the polymer was taken out, separated from the solvent by filtration and dried. Irganox 1010 (manufactured by Ciba Specialty Chemicals: trade name) 1000 ppm, Irgafos 168 (manufactured by Ciba Specialty Chemicals: trade name) 1000 in the obtained ethylene / α-olefin copolymer powder.
ppm and calcium stearate 1500 ppm
Are mixed and pre-mixed, and then melt-kneaded using a twin-screw extruder (Laboplast Mill, manufactured by Toyo Seiki Co., Ltd.) under the conditions of a screw rotation speed of 20 rpm and a barrel set temperature of 220 ° C. to obtain ethylene / α. -Olefin copolymer pellets were obtained. MFR of the obtained pellets is 0.57 g / 1
0 min, density 0.9302 g / cm ³ , melting point 12
It was 3.3 ° C. Table 1 shows the characteristic values of the ethylene / α-olefin copolymer.

Comparative Example 1 Ethylene was prepared in the same manner as in Example 1 except that, in place of the catalyst used in Example 1, a slurry containing 50 mg of the catalyst (B) obtained by the method of Catalyst Preparation Example 2 was sequentially added. / Α-
Olefin copolymer pellets were obtained. The obtained pellets had an MFR of 1.73 g / 10 min and a density of 0.933.
It was 1 g / cm ³ and the melting point was 124.0 ° C. Table 1 shows the characteristic values of the ethylene / α-olefin copolymer.

Example 2 The charging amount of 1-butene of Example 1 was changed from 159 g to 39 g.
Ethylene / in the same manner as in Example 1 except that
α-Olefin copolymer pellets were obtained. Obtained Pele
MFR is 2.46g / 10min, density is 0.9
317 g / cm ³The melting point was 124.4 ° C. Echi
The characteristic values of the ren / α-olefin copolymer are shown in Table 1.

[0090]

[Table 1]

EFFECT OF THE INVENTION Since the ethylene / α-olefin copolymer of the present invention has excellent long-term creep properties, it is possible to highly improve the balance between rigidity, moldability and long-term creep properties as compared with conventional polyethylene. Extrusion molding materials such as pipes, sheets, tapes, coating materials, industrial materials, detergent containers, chemical containers, medical containers, food containers, hollow molding materials such as various industrial materials, home appliance parts, industrial It is suitable as a material for a wide range of applications such as parts for molding, containers, injection molding materials such as sundries, various film materials, various fiber materials.

Claims (4)

[Claims] 1. An ethylene-containing α-olefin having 3 to 20 carbon atoms, wherein (1) MFR is 0.01 to 20 g / 10.
min and (2) density is 0.910 to 0.960 g
A / cm ^{3, (3)} by repeated tensile fatigue test, measurement temperature 80 ° C., the number of repetitions until rupture as measured at an applied stress 6 MPa (N), gel permeation chromatography (GPC) In the relationship of molecular weight-elution amount obtained by measurement, the critical molecular weight (M
The ratio (Pc) of the elution amount above c) and the total elution amount is logN ≧ 17.0Pc-1.00 Pc = (elution amount above the critical molecular weight (Mc) capable of forming Thai molecules) / total elution amount An ethylene / α-olefin copolymer characterized by satisfying: 2. A critical molecular weight (Mc) capable of forming a Thai molecule.
The ethylene / α according to claim 1, wherein the ratio (Pc) of the above-mentioned elution amount to the total elution amount is 0.150 or more.
-Olefin copolymers. 3. A Ziegler-Natta catalyst prepared by using an ethylene / α-olefin copolymer as a raw material, a homogeneous solution obtained from metal magnesium, alcohol, titanium alkoxide, an oxygen-containing organic compound and an organoaluminum halide. The ethylene / α-olefin copolymer according to claim 1 or 2, which is produced by a slurry polymerization method. 4. The ethylene / α-olefin copolymerization product according to claim 1, wherein the α-olefin is any of 1-butene, 1-pentene, 1-hexene and 1-octene. Coalescing.