JP2003327757A - Polyethylene resin composition and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive novel polyethylene resin composition not only having together mechanical properties and moldability but also having an excellent ESCR, impact strength and melt tension. <P>SOLUTION: The polyethylene resin composition having excellent moldability and mechanical properties is obtained by reacting an ethylene polymer and a radical generator in the presence of a Ziegler-Natta catalyst improved in copolymerizability. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyethylene resin composition having excellent mechanical properties and moldability, and a method for producing the same. More specifically, it relates to a polyethylene resin composition excellent in ESCR, impact strength and melt tension, and a method for producing the same.

[0002]

2. Description of the Related Art At present, polyethylene resin compositions obtained with Ziegler-Natta catalysts are used in many applications due to their performance. For example, various methods for producing an ethylene copolymer having excellent mechanical strength such as rigidity, environmental stress crack resistance (ESCR), and impact strength have been proposed for a container formed by blow molding. If the density is increased to obtain rigidity, the ESCR and impact strength will be poor and the ESCR
When the density is lowered to obtain the impact strength and the rigidity is deteriorated, and it is not enough to simply set the density in order to obtain a product in which the contradictory physical properties are balanced.

Further, as a method for improving the molding processability of polyethylene, measures such as improvement of a polymerization catalyst or improvement by a polymerization process can be taken. However, the result is poor mechanical strength and sufficient results. Has not yet reached. In addition to this, a method of broadening the molecular weight distribution for the purpose of maintaining mechanical strength while maintaining processability is used, but the obtained ethylene-based polymer has an improved discharge rate and reduced extrusion load during molding, Moldability, such as improvement of melt tension and molding skin of molded products, was not always satisfactory. Further, as a method of improving moldability, a method of blending high-density polyethylene and linear low-density polyethylene as disclosed in JP-A-10-195261 has been proposed. In carrying out this method, equipment for blending is newly required, which is not preferable in terms of cost in an actual production plant. Further, for injection blow applications as disclosed in JP-A-11-106429, improvement of molding processability by a method using a radical generator is described. However, the obtained ethylene-based polymer is still unsatisfactory in terms of mechanical properties, moldability such as improvement of discharge amount during molding, reduction of extrusion load, improvement of melt tension and molding surface of molded products.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to inexpensively supply a polyethylene resin composition having both mechanical properties and molding processability. More specifically, the object is to provide a novel polyethylene resin composition having excellent ESCR, impact strength and melt tension.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor reacted an ethylene polymer with a Ziegler-Natta catalyst having improved copolymerizability and a radical generator. It was found that a polyethylene resin composition excellent in molding processability and mechanical properties can be obtained.

That is, according to the present invention, ethylene produced by using a Ziegler-Natta catalyst and α- having 3 to 12 carbon atoms are used.
A polyethylene resin composition obtained by adding 0.001 to 0.05 parts by weight of a radical generator to 100 parts by weight of an ethylene-based polymer composed of an olefin, which comprises the following a):
To d) are satisfied, and a polyethylene resin composition and a method for producing the same.

A) The melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g is 0.1 to 10 g / 1.
0 minutes, b) the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by GPC (gel permeation chromatography) is 3 to 20, and c) GPCFTIR ( Obtained by gel permeation chromatography-Fourier transform infrared spectrometer) 1
The molecular weight existing between x10 ^{4 and} 1x10 ⁶ was fractionated into at least 20 points, and the logarithm of each fractionated molecular weight (X) Lo
The number of branches (Y) contained in each of those components obtained for g (X) and the value of a in the linear regression equation Y = a × Log (X) + b are positive, and d) melt tension ( MS) satisfies the formula (1) Log (MS) ≧ −0.907 × Log (MFR) +0.52 (1).

A catalyst system and a production method for obtaining the ethylene polymer of the present invention will be described.

The catalyst system and the production method for obtaining the ethylene-based polymer of the present invention are not particularly limited as long as the ethylene-based polymer of the present invention can be produced, but the productivity, production cost and the like are good. For a certain reason, a Ziegler-Natta catalyst prepared by using metal magnesium, alcohol, a homogeneous solution obtained from titanium alkoxide, an oxygen-containing organic compound, and an organoaluminum halide as raw materials is preferably used. The method for producing the catalyst system and the polyethylene resin composition exemplified in the present invention will be shown below.

Preparation examples of the Ziegler-Natta catalyst which is preferably used in the present invention and which is prepared by using metal magnesium, alcohol, a homogeneous solution obtained from titanium alkoxide, an organic compound containing oxygen and an organoaluminum halide as raw materials explain.

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, that is, any shape such as powder, particles, foil or ribbon can be used.

As alcohols, straight-chain or branched-chain aliphatic alcohols having 1 to 18 carbon atoms or 3 to 1 carbon atoms
A cycloaliphatic alcohol of 8 can be used. Examples include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, n-hexanol, 2-ethylhexanol, n-octanol, i.
-Octanol, n-stearyl alcohol, cyclopentanol, cyclohexanol, ethylene glycol and the like.

These alcohols are used alone or as a mixture of two or more kinds. It is of course good to use it alone, but when used as a mixture of two or more,
It may produce a unique effect on the powder properties 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 that reacts with magnesium metal or forms an addition compound, such as iodine. It is preferred 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 represents a hydrocarbon group such as a linear or branched alkyl group having 1 to 10 carbon atoms, preferably a cycloalkyl group, an arylalkyl group, an aryl group and an alkylaryl group, and 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 tetra-i-propoxide, titanium tetra-n-butoxide,
Hexa-i-propoxydititanate and the like can be mentioned. 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 and acid anhydrides are used.

As the ethers, diethyl ether,
Dibutyl ether, diamyl ether, methylphenyl 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 bromionate, methyl benzoate, ethyl benzoate, methyl toluate, ethyl toluate, methyl anisate and ethyl anisate. Can be mentioned.

As the ketones, acetone, ethyl methyl ketone, cyclobutanone, cyclopentanone, cyclohexanone, acetophenone, propiophenone, benzophenone, dibenzyl ketone, diacetyl, acetylbenzoyl, benzyl, acetylacetone, benzoylacetone, dibenzoylmethane, Acetonylacetone etc. are mentioned.

Examples of acid anhydrides include succinic acid, glutaric acid and phthalic acid. Diethers, polyethers, esters, diketones and the like containing a plurality of oxygen atoms are preferable for the reason that the elution ratio to the solvent during the polymerization reaction is small and the change with time of the catalyst is small. Particularly preferred are diethers and polyethers.

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 halogenated organoaluminum compound include dimethyl aluminum chloride, diethyl aluminum chloride, diethyl aluminum bromide, dipropyl aluminum chloride, ethyl aluminum dichloride, i-butyl aluminum dichloride, methyl aluminum sesquichloride and ethyl aluminum. Examples include sesquichloride, i-butylaluminum sesquichloride, a mixture of triethylaluminum and aluminum trichloride, and the like.

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.

Further, 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 these, as the polysiloxane, chain polysiloxane and cyclic polysiloxane can be mentioned.

Specific examples of the chain polysiloxane include hexamethyldisiloxane, octamethyltrisiloxane, dimethylpolysiloxane, diethylpolysiloxane, methylethylpolysiloxane, methylhydropolysiloxane, ethylhydropolysiloxane, 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,
2,4,6,8-tetramethylcyclotetrasiloxane, triphenyltrimethylcyclotrisiloxane, tetraphenyltetramethylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, octaphenylcyclotetrasiloxane and the like can be mentioned.

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 be liquid for handling, and the viscosity at 25 ° C. is 1 to 1000.
It is desirable that it is in the range of 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 silane hydrocarbons such as trimethylphenylsilane, dimethyldiphenylsilane and allyltrimethylsilane, and chain and cyclic organic silanes such as hexamethyldisilane and octaphenylcyclotetrasilane. , Organosilane such as methylsilane, dimethylsilane and trimethylsilane, silicon halide such as silicon tetrachloride and silicon tetrabromide, dimethyldichlorosilane, diethyldichlorosilane, n-
Butyltrichlorosilane, diphenyldichlorosilane,
Alkyl and aryl halogenosilanes such as triethylfluorosilane and dimethyldibromosilane, trimethylmethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, diphenyldiethoxysilane, tetramethyldiethoxydisilane, dimethyltetra 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 the magnesium metal, the alcohols and the titanium alkoxide for producing the homogeneous solution of the present invention may be any order as long as a chemical reaction occurs. 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 metal magnesium, alcohol and an oxygen-containing organic compound. The above-mentioned homogeneous solution can be obtained by such a method.

The reaction between the homogeneous solution and the organoaluminum halide is preferably carried out in a liquid medium. As the solvent, all those usually used in the art can be used, and examples thereof include aliphatic, alicyclic or aromatic hydrocarbons, halogen derivatives thereof, or a mixture thereof, for example, isobutane and hexane. , Heptane, cyclohexane, benzene, toluene,
Xylene and monochlorobenzene are preferably used.

The amount of magnesium, alcohols, and titanium alkoxide used in the present invention is the atomic ratio of the gram atom of metallic magnesium (Mg) to the gram atom of Ti of the titanium alkoxide of (ii) above. 0.2 ≦ M
g / Ti ≦ 100, preferably 1 ≦ Mg / Ti ≦ 3
0, particularly preferably 4 <Mg / Ti ≦ 20. Mg
When / Ti exceeds 100, 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 necessary 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 precipitated 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 between 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, the halogenated organoaluminum compound R ² _z A
Z of 1X3 _-z is 1 ≦ Z ≦ 2, the amount of Mg used (molar ratio) is 0.5 to 2.0, and in the latter-stage reaction, 0 <
Z <2, the usage amount (molar ratio) to Mg is 1.0 to 20
It is preferable that

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 at 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 at a temperature 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 under atmospheric pressure or under pressure in an active gas atmosphere.

The Ziegler-Natta catalyst thus obtained is
It can be used without removing remaining unreacted substances and by-products, or after removing by filtration or a gradient method.

When carrying out the polymerization using the above Ziegler-Natta catalyst, an organoaluminum compound is usually used as a co-catalyst for the purpose of promoting the expression of catalytic activity. Preferred are organoaluminum compounds having a linear or branched alkyl group having 1 to 10 carbon atoms. It is particularly preferable to use a trialkylaluminum having a linear or branched alkyl group having 1 to 10 carbon atoms. In particular,
Examples thereof include trimethylaluminum, triethylaluminum, tri-i-butylaluminum, 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 two or more kinds may be mixed or reacted and used.

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

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

The ethylene polymer of the present invention is an ethylene polymer composed of ethylene and an α-olefin having 3 to 12 carbon atoms, and is not particularly limited as long as it is 3 to 12, and when it exceeds 12, It is not preferable because the polymerizability becomes low and the desired effect cannot be obtained. Where the carbon number is 3
Examples of the α-olefin of 12 include propylene,
1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-eicosene, 4-methyl-1-pentene and the like can be mentioned.

The polymerization of ethylene and the α-olefin having 3 to 12 carbon atoms according to the present invention can be carried out under the general reaction conditions of the so-called Ziegler method. That is, the polymerization is carried out at a temperature of 20 to 110 ° C. in a continuous system or a batch system. The polymerization pressure is not particularly limited, but is preferably 0.15 to 5 under pressure.
Use of 5 MPa is suitable. When the polymerization is carried out in the presence of an inert solvent, any commonly used inert solvent can be used. Especially carbon number 3-20
Alkanes or cycloalkanes such as propane, isobutane, pentane, hexane, cyclohexane and the like are suitable.

When the polymerization is carried out in the gas phase, the reactor used in the polymerization step may be a fluidized bed type polymerizer, a stirred tank type polymerizer or the like, as long as it is one usually used in the art. You can When a fluidized bed type polymerizer is used, it is carried out by blowing a gaseous olefin and / or an inert gas into the system while keeping the reaction system in a fluidized state. In the case of using the stirring tank type polymerizer, various types of stirrers such as an Ikari type stirrer, a screw type stirrer, and a ribbon type stirrer can be used as the stirrer.

The polymerization operation of the present invention can be carried out not only in one-stage polymerization which is usually carried out under one polymerization condition, but also in multi-step polymerization which is carried out under a plurality of polymerization conditions.

In the practice of the present invention, the Ziegler-Natta catalyst is preferably used in an amount corresponding to 0.001 to 2.5 mmol of titanium atom per liter of solvent or per liter of reactor. It is also possible to use a higher concentration depending on the conditions.

The organoaluminum compound as a cocatalyst was added in an amount of 0.1% per liter of the solvent or 1 liter of the reactor.
It is used at a concentration of 02 to 50 mmol, preferably 0.2 to 5 mmol. In the present invention, the molecular weight of the polymer produced can be adjusted by a known means, that is, by allowing a suitable amount of hydrogen to exist in the reaction system. When an ethylene-based polymer is produced by multistage polymerization of two or more stages, a polymer having a different molecular weight is produced in each stage,
The order is arbitrary. Further, in this case, regarding the amount of the supplied comonomer, in order to obtain a polymer having a high ESCR, it is desirable to supply a large amount of the comonomer in the step of producing a polymer having a higher molecular weight.

In the present invention, the molecular weight and the production ratio of the polymer produced in each stage are not particularly limited as long as the conditions are such that an ethylene polymer having a molecular weight distribution within the above-mentioned specific range is obtained.

In the present invention, after polymerization is carried out using the above-mentioned catalyst, a radical generator is added to the obtained ethylene polymer to decompose and react the radical generator.

In the polyethylene resin composition of the present invention, the melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g is 0.1 to 10 g / 10 minutes. When it is less than 0.1, the moldability is poor, and when it exceeds 10, not only the effect of improving the melt tension due to the effect of the crosslinking agent does not appear but also the strength is lowered, which is not preferable.

In the polyethylene resin composition of the present invention, the weight average molecular weight (M
w) and number average molecular weight (Mn) ratio (Mw / Mn) is 3
~ 20. When it is less than 3, the moldability is poor, and when it exceeds 20, the impact strength is lowered, which is not preferable.

Further, in the polyethylene resin composition of the present invention, 1 × 10 ⁴ to 1 × obtained by GPCFTIR.
The molecular weight existing between 10 ⁶ is divided into at least 20 points, and the logarithm Log (X) of each molecular weight (X) obtained by the classification is obtained, and the linear number with the number of branches (Y) contained in each component thereof is obtained. The value of a in the regression equation Y = a × Log (X) + b is positive. When a is negative, the ESCR cannot be improved due to the branch introduction into the high molecular weight component, which is not preferable.

In the polyethylene resin composition of the present invention, the melt tension (MS) satisfies the following expression (1) Log (MS) ≧ −0.907 × Log (MFR) +0.52 (1). To do. If this formula is not satisfied, excellent moldability cannot be obtained, which is not preferable.

The polyethylene resin composition obtained by the method of the present invention is a modified polyethylene resin without impairing the homogeneity of the raw material polyethylene resin and has good moldability and mechanical properties. is there. That is, since the HLMFR and MFR values, which are considered to be a measure of moldability, can be increased to desired values, the discharge amount of the extruder can be increased and the productivity can be improved, and deburring is easy in blow molding. It is possible to provide a hollow molded article having a good surface texture.

The radical generator used in the present invention is
Organic peroxides such as hydroperoxides, dialkyl peroxides, peroxyesters and the like and azo compounds are preferable, and those having a decomposition temperature of more than 100 ° C. for obtaining a half-life of 1 minute are preferable.

As a specific example, as the organic peroxide, α, α'-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, t-butyl hydroperoxide, 1,3-bis ( t-butylperoxyisopropyl) benzene, di-t-butylperoxide, 2,5-di (t-butylperoxy) hexane, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di ( t-butylperoxy) -3-hexyne, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butylperoxyphthalate, and the like, azo compounds such as dimethyl-2, 2'-azobisisobutyrate, 2,2'-azobis-isobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'- Zobis-2-methylbutyronitrile, 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis-4-cyanovaleric acid, 1 , 1'-azobis (1-acetoxy-1-
Examples thereof include those having a one-minute half-life temperature of 100 ° C. or higher.

The above radical generators may be used alone or in combination of plural kinds.

The amount of the radical generator added is in the range of 0.001 to 0.05 parts by weight per 100 parts by weight of the ethylene polymer. When the amount is less than 0.001 part by weight, the result of modification of polyethylene is not significant. Also 0.05
If the amount is more than parts by weight, the reforming reaction proceeds excessively, and the quality of the molded product is impaired.

Any method may be used for the reaction, but the following methods are mentioned as specific examples.

1) After the completion of the polymerization, at the time of pelletizing the ethylene-based polymer, a radical generator is simultaneously fed to cause a melt extrusion reaction.

2) A masterbatch containing a large amount of a radical generator is prepared in advance, and the masterbatch and the above copolymer pellets are blended, extruded and reacted.

[0071]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In addition, various physical property tests in Examples and Comparative Examples were performed by the following methods, and the results are shown in Table 1.
It was shown to. Here, the calculated MS is Log (MS) = − 0.
It is a value obtained by 907 × Log (MFR) +0.52. <Melt flow rate> 2.16 kg and 21.6 kg
Melt flow rate by load (MFR and HLMF
R) was measured according to conditions 4 and 7 of JIS K-7210 (1995). <GPC> Device: HLC-8121G manufactured by Tosoh Corporation
PC / HT measurement conditions, solvent: trichlorobenzene + antioxidant (B
HT 0.05%), flow rate: 1.0 ml / min, sample concentration: 1.0 mg / ml, injection volume: 0.3 ml, column:
TSKgel GMHHR-H (20) HT (3),
Column temperature: 140 ° C, detector: HLC-8121GP
C / HT <GPCFTIR> Device: SEC 150C (manufactured by Waters) Measuring conditions, solvent: trichlorobenzene, flow rate: 0.5 m
1 / min, sample concentration: 3.0 mg / ml, injection amount: 0.3
ml, column: shodex AD-806MS (2
Book), column temperature: 140 ° C, detector: MCT, Mag
na500 (manufactured by Nicolet) <Density> Using an MFR meter with a hood, 190 ° C., 5k
The sample extruded under g load was cooled in the hood for 5 minutes, and then measured by a density gradient tube at 23 ° C. <Charpy impact value> JIS K-7111 (1996
(Year) “Charpy impact strength test”. <ESCR> Measured according to the measuring method of "constant strain environmental stress crack test" of JIS K-6760 (1981). As the test solution, a 10 wt% aqueous solution of Nonion NS-210 manufactured by NOF CORPORATION was used. <Melt Tension (MS)> Using "Capillograph 1B" manufactured by Toyo Seiki Co., Ltd., an ethylene-based polymer sample melted at 190 ° C. was passed through an orifice having a diameter of 2.1 mm and a length of 8 mm,
Tensile strength was obtained when the material was extruded at a barrel diameter of 9.6 mm and an extrusion speed of 10 mm / min and pulled at 10 m / min.

Example 1 <Preparation of catalyst component (1)> In a 10-liter stainless steel autoclave equipped with a stirrer, 2-ethyl-1-
Hexanol 385.5 g (2.96 mol) and n-butanol 219.4 g (2.96 mol) were put, and iodine 2.0 g and metallic magnesium powder 60 g (2.47) were added.
Mol) and titanium tetrabutoxide 166.8 g
(0.49 mol) was added, 2.0 liters 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. Continue 1
The temperature was raised to 20 ° C and the reaction was carried out for 1 hour.
A homogeneous solution containing This homogeneous solution was cooled to 45 ° C. and 51.0 g (0.49 g of 1,2-dimethoxypropane) was added.
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 i-butylaluminum dichloride was added over 2 hours. 70 ℃ after adding everything
After stirring for 1 hour, 355.6 g of a Ziegler-Natta catalyst (catalyst component (1)) having a Ti content of 6.6 wt% was obtained. The resulting catalyst component was used as hexane slurry in the next polymerization step after removing unreacted materials and by-products remaining with hexane. <Polymerization> Dehydrated and refined hexane 158 liters / Hr in a polymerization vessel having an internal volume of 370 liters, and triisobutylaluminum as an organoaluminum compound 67 mmol /
Hr, the above catalyst component (1) was continuously supplied at a rate of 3.76 g / Hr, while discharging the polymerization contents at a required rate, ethylene was supplied at a rate of 25.0 kg / Hr at 85 ° C., Maintain ethylene concentration 0.81wt%, hydrogen to ethylene concentration ratio 0.21mol / mol, 1-butene to ethylene concentration ratio 3.33g / g, total pressure 2.9MP.
Polymerization was continuously performed in a liquid-filled state under the conditions of aG and an average residence time of 2.0 hours. The slurry from the polymerization vessel was flushed with unreacted gas in a depressurization tank, and then separated and dried to obtain an ethylene polymer powder. <Production of polyethylene resin composition> To 100 parts by weight of the obtained ethylene polymer powder, 0.1 parts by weight of Irganox 1010 (trade name, manufactured by Ciba Geigy), which is a phenolic stabilizer, and calcium stearate are added. 0.
1 part by weight, and further 0.003 parts by weight of α, α'-bis (t-butylperoxy) diisopropylbenzene as a radical generator were added, and a uniaxial 65 m manufactured by Placo Co., Ltd. was added.
Pelletized at 180 [deg.] C. with m extruder PDA-65. The MFR of the obtained polyethylene resin composition is 1.1.
g / 10 minutes, HLMFR 31.0 g / 10 minutes, density 935 kg / m ³ , Charpy impact value 13 kJ / m ² ,
ESCR was 260 Hr, MS was 3.1 g, molecular weight distribution (Mw / Mn) by GPC was 3.6, and the value of a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR was 0.0093. there were. The branching degree distribution with respect to the molecular weight obtained by GPCFTIR is shown in FIG.

[0073]

[Table 1] Example 2 <Preparation of catalyst component (2)> In the method for producing the catalyst component (1) described in Example 1, 2,2-dibutyl-1,3-dimethoxypropane was used in place of 1,2-dimethoxypropane. A catalyst was prepared in the same manner except that it was used. As a result, 378.6 g of a catalyst component (2) which was a Ziegler-Natta catalyst having a Ti content of 6.2% by weight was obtained. <Polymerization> Using the above catalyst component (2), ethylene concentration 0.85 wt%, hydrogen to ethylene concentration ratio 0.1.
1 mol / mol, 1-butene to ethylene concentration ratio 6.
Polymerization was continuously carried out in the same manner as in Example 1 except that the conditions were 43 g / g to obtain an ethylene polymer powder. <Production of polyethylene resin composition> 0.005 parts by weight of α, α'-bis (t-butylperoxy) diisopropylbenzene as a radical generator is added to 100 parts by weight of the obtained ethylene polymer powder. Except for the above, pelletization was performed in the same manner as in Example 1. The MFR of the obtained polyethylene resin composition was 0.6 g / 10 minutes,
HLMFR is 18.2g / 10min, density is 927kg /
m ³ , Charpy impact value is 14 kJ / m ² , ESCR is 1
000 Hr or more, MS is 5.3 g, molecular weight distribution (Mw / Mn) by GPC is 3.8, a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR
Was 0.0038.

Example 3 <Production of Polyethylene Resin Composition> Dimethyl-2,2′-azobisisobutyrate was added as a radical generator to 100 parts by weight of the powder of the ethylene polymer obtained in Example 1. Pelletization was performed in the same manner as in Example 1 except that 0.01 part by weight was added. The polyethylene resin composition thus obtained had an MFR of 1.6 g / 10 minutes, HLMFR
Is 41.9 g / 10 minutes, density is 935 kg / m ³ , Charpy impact value is 13 kJ / m ² , ESCR is 260 H
r and MS are 2.4 g, molecular weight distribution by GPC (Mw /
Mn) is 3.4, and the value of a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR is 0.0.
It was 093.

Example 4 <Polymerization> 158 liter / Hr of hexane dehydrated and purified in a polymerization vessel having an inner volume of 370 liter, and 34 mmol / triisobutylaluminum as an organoaluminum compound.
Hr, 1.2 g of the catalyst component (1) obtained in Example 1
24.0 kg of ethylene at 85 ° C. while continuously feeding at a rate of Hr and discharging the polymerization content at a required rate.
/ Hr, the ethylene concentration is 0.87 wt%,
Hydrogen concentration ratio to ethylene 0.22 mol / mol, 1-
While maintaining the butene to ethylene concentration ratio at 2.64 g / g, the polymerization was continuously carried out in a liquid-filled state under the conditions of a total pressure of 2.9 MPaG and an average residence time of 2.0 Hr. After flushing the unreacted gas in the depressurization tank with the slurry from the polymerization vessel,
An ethylene polymer powder was obtained through the separation and drying steps. <Production of Polyethylene Resin Composition> Addition of 0.01 parts by weight of 1,1′-azobis-1-cyclohexanecarbonitrile as a radical generator to 100 parts by weight of the obtained ethylene polymer powder is excluded. The conditions were pelletized in the same manner as in Example 1. The polyethylene resin composition thus obtained had an MFR of 0.6 g / 10 minutes, HLMFR
Is 19.1 g / 10 minutes, density is 942 kg / m ³ , Charpy impact value is 15 kJ / m ² , ESCR is 310 H
5.4 g for r and MS, molecular weight distribution (Mw /
Mn) is 3.9, and the value of a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR is 0.0.
It was 012.

Example 5 <Polymerization> 143 liters / Hr of hexane dehydrated and refined in a first polymerization vessel having an internal volume of 370 liters, and triisobutylaluminum as an organoaluminum compound was 54 mmo.
1 / Hr, the catalyst component (1) used in Example 1 was 1.84.
While continuously feeding at a rate of g / Hr and discharging the polymerization content at a required rate, ethylene was added at 24.0% at 85 ° C.
Supply at a rate of kg / Hr, ethylene concentration 1.35 wt
%, The concentration ratio of hydrogen to ethylene was maintained at 0.53 mol / mol, and the first-stage polymerization was continuously carried out in a full state under the conditions of total pressure of 2.9 MPaG and average residence time of 2.2 Hr. The hexane slurry containing the ethylene polymer obtained in the first polymerization vessel was introduced into a second polymerization vessel having an internal volume of 545 liters after flushing unreacted gas in a depressurization tank,
Solid catalyst component and alkylaluminum were not added, and hexane was supplied at 133 liter / Hr. While discharging the contents of the polymerization vessel at a required rate, ethylene was supplied at a rate of 24.0 kg / Hr at 80 ° C. Concentration 1.
41 wt%, hydrogen concentration ratio to ethylene 0.033 mol
/ Mol, ratio of ethylene concentration of 1-butene to 2.32 g /
g, total pressure 2.0 MPaG, average residence time 1.7H
Second stage polymerization was carried out under the condition of r. After flushing unreacted gas in the depressurization tank with the slurry from the second polymerization vessel,
An ethylene polymer powder was obtained through the separation and drying steps. <Production of polyethylene resin composition> 0.003 parts by weight of α, α'-bis (t-butylperoxy) diisopropylbenzene as a radical generator is added to 100 parts by weight of the obtained ethylene polymer powder. Except for the above, pelletization was performed in the same manner as in Example 1. The MFR of the obtained polyethylene resin composition was 0.7 g / 10 minutes,
HLMFR is 52.9 g / 10 minutes, density is 950 kg /
m ³ , Charpy impact value is 16 kJ / m ² , ESCR is 1
000 hours or more, MS is 4.8 g, molecular weight distribution (Mw / Mn) by GPC is 9.9, and a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR.
Was 0.005.

Example 6 <Polymerization> 143 liters / Hr of hexane dehydrated and purified in a first polymerization vessel having an inner volume of 370 liters, and 61 mmo of triisobutylaluminum as an organoaluminum compound.
1 / Hr, the catalyst component (1) used in Example 1 was 2.94.
25.0% of ethylene at 85 ° C. while continuously feeding at a rate of g / Hr and discharging the polymerization content at a required rate.
Supply at a rate of kg / Hr, ethylene concentration 1.18 wt
%, The concentration ratio of hydrogen to ethylene was kept at 0.58 mol / mol, and the first stage of polymerization was continuously carried out in a full state under the conditions of total pressure of 2.9 MPaG and average residence time of 2.2 Hr. The hexane slurry containing the ethylene polymer obtained in the first polymerization vessel was introduced into a second polymerization vessel having an internal volume of 545 liters after flushing unreacted gas in a depressurization tank,
Solid catalyst component and alkylaluminum were not added, and hexane was supplied at 133 liters / hr, and while the contents of the polymerization vessel were discharged at a required rate, ethylene was fed at a rate of 25.5 kg / hr at 80 ° C. Concentration 0.
80 wt%, hydrogen to ethylene concentration ratio 0.056 mol
/ Mol, ratio of ethylene concentration of 1-butene to 4.61 g /
g, total pressure 2.0 MPaG, average residence time 1.7H
Second stage polymerization was carried out under the condition of r. After flushing unreacted gas in the depressurization tank with the slurry from the second polymerization vessel,
An ethylene polymer powder was obtained through the separation and drying steps. <Production of polyethylene resin composition> 0.015 parts by weight of α, α′-bis (t-butylperoxy) diisopropylbenzene as a radical generator is added to 100 parts by weight of the obtained ethylene polymer powder. Except for the above, pelletization was performed in the same manner as in Example 1. The MFR of the obtained polyethylene resin composition was 0.8 g / 10 minutes,
HLMFR is 71.2 g / 10 minutes, density is 948 kg /
m ³ , Charpy impact value is 14 kJ / m ² , ESCR is 1
000 hours or more, MS is 4.5 g, molecular weight distribution (Mw / Mn) by GPC is 10.3, and the value of a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR is 0.012. It was

Comparative Example 1 <Preparation of catalyst component (3)> n-butanol 4 was placed in a 10-liter stainless steel autoclave equipped with a stirrer.
02.8 g (5.43 mol) was added, and iodine 2.
Hydrogen gas generated by adding 0 g, 60 g (2.47 mol) of magnesium metal powder and 252.2 g (0.74 mol) of titanium tetrabutoxide, and further adding 2.0 liters of hexane and heating to 80 ° C. Was stirred under a nitrogen blanket for 1 hour. Subsequently, the temperature was raised to 120 ° C. and the reaction was carried out for 1 hour to obtain a uniform solution containing Mg and Ti. Subsequently, the internal temperature of the autoclave was maintained at 45 ° C., and 2297 g (7.41 mol) of a 50% hexane solution of i-butylaluminum dichloride was added over 2 hours. After all the ingredients were added, the mixture was stirred at 70 ° C. for 1 hour to obtain 454.4 g of a Ziegler-Natta catalyst (catalyst component (3)) having a Ti content of 7.8 wt%. The resulting catalyst component was used as hexane slurry in the next polymerization step after removing unreacted materials and by-products remaining with hexane. <Polymerization> Dehydrated and refined hexane 158 liters / Hr in a first polymerization vessel having an inner volume of 370 liters, and triisobutylaluminum 67 as an organoaluminum compound (B).
mmol / Hr, 1.38 g of the above solid catalyst component (A)
54.0 k of ethylene at 85 ° C. while continuously feeding at a rate of / Hr and discharging the polymerization content at a required rate.
Supply at a rate of g / Hr, ethylene concentration 0.71 wt
%, Hydrogen concentration ratio to ethylene 0.12 mol / mol,
The concentration of 1-butene to ethylene was kept at 3.2 g / g, and the polymerization was continuously carried out in a full state under the conditions of total pressure of 2.9 MPaG and average residence time of 1.7 hr. The hexane slurry from the polymerization vessel was flushed with unreacted gas in a depressurization tank, and then separated and dried to obtain an ethylene polymer powder. <Production of Polyethylene Resin Composition> Dimethyl-2,2′-azobisisobutyrate as a radical generator was added to 100 parts by weight of the obtained ethylene polymer powder.
Pelletization was carried out in the same manner as in Example 1 except that 003 parts by weight was added. The polyethylene resin composition thus obtained had an MFR of 1.5 g / 10 minutes and an HLMFR of 39.
6 g / 10 minutes, density 939 kg / m ³ , Charpy impact value 7 kJ / m ² , ESCR 90 Hr, MS 2.
3 g, the molecular weight distribution (Mw / Mn) by GPC is 3.
8, linear regression equation Y = a × obtained by GPCFTIR
The value of a in Log (X) + b was -0.0092. The branching degree distribution with respect to the molecular weight determined by GPCFTIR is shown in FIG.

Comparative Example 2 <Preparation of catalyst component (4)> In a 10-liter stainless steel autoclave equipped with a stirrer, 108.2 g (1.80 mol) of i-propanol and 13 of n-butanol were added.
4.6 g (1.82 mol) was added, and iodine 2.0 was added to this.
g, 40 g (1.65 mol) of magnesium metal powder, and 224.1 g (0.66 mol) of titanium tetrabutoxide, and then 2.0 liters of hexane were added and the temperature was raised to 80 ° C. to generate hydrogen gas. Was stirred under a nitrogen blanket for 1 hour. Subsequently, the temperature was raised to 120 ° C. and the reaction was carried out for 1 hour to obtain a uniform solution containing Mg and Ti. Keeping the internal temperature of the autoclave at 45 ° C, a 30% hexane solution of diethylaluminum chloride 1.
32 kg (3.3 mol) was added over 1 hour. After adding everything, the mixture was stirred at 60 ° C. for 1 hour. Next, 197.0 g (3.3 g atom of silicon) of methylhydropolysiloxane (viscosity of 30 centistokes at 25 ° C.) was added, and the mixture was reacted under reflux for 1 hour. After cooling to 45 ° C, i-
2.81 kg (9.1 mol) of a 50% hexane solution of butylaluminum dichloride was added over 2 hours. After all the ingredients were added, the mixture was stirred at 70 ° C. for 1 hour to obtain 287.4 g of a Ziegler-Natta catalyst (catalyst component (4)) having a Ti content of 11 wt%. Obtained catalyst component (4)
Hexane was used to remove remaining unreacted materials and by-products, and then used as a hexane slurry in the next polymerization step. <Polymerization> Dehydrated and purified hexane 158 liters / Hr and triisobutylaluminum as an organoaluminum compound 67 mmo in a first polymerization vessel having an internal volume of 370 liters.
1 / Hr, the above catalyst component (4) was continuously supplied at a rate of 0.55 g / Hr, and ethylene was supplied at a rate of 47.0 kg / Hr at 85 ° C. while discharging the polymerization contents at a required rate. Then, the ethylene concentration was 2.07 wt%, the hydrogen concentration ratio to ethylene was 0.15 mol / mol, and the 1-butene concentration ratio to ethylene was 0.51 g / g, and the total pressure was 2.9 M.
Polymerization was continuously performed in a liquid-filled state under the conditions of PaG and an average residence time of 1.8 hr. The hexane slurry from the polymerization vessel was flushed with unreacted gas in a depressurization tank, and then separated and dried to obtain an ethylene polymer powder. <Production of Polyethylene Resin Composition> 0.001 part by weight of 1,1′-azobis-1-cyclohexanecarbonitrile as a radical generator is added to 100 parts by weight of the obtained ethylene polymer powder. The conditions were pelletized in the same manner as in Example 1. The polyethylene resin composition thus obtained had an MFR of 0.8 g / 10 minutes, HLMF
R is 30.3 g / 10 min, density is 951 kg / m ³ , Charpy impact value is 8 kJ / m ² , ESCR is 70 Hr,
MS is 4.2 g, molecular weight distribution by MPC (Mw / M
n) is 6.8, and the value of a in the linear regression equation Y = a * Log (X) + b obtained by GPCFTIR is -0.0.
It was 2.

Comparative Example 3 <Polymerization> 143 liters / Hr of hexane dehydrated and purified in a first polymerization vessel having an internal volume of 370 liters, and triisobutylaluminum as an organoaluminum compound was 61 mmo.
1 / Hr, the catalyst component (1) used in Example 1 was 2.94.
25.0% of ethylene at 85 ° C. while continuously feeding at a rate of g / Hr and discharging the polymerization content at a required rate.
Supply at a rate of kg / Hr, ethylene concentration 1.18 wt
%, Hydrogen concentration ratio to ethylene 0.38 mol / mol,
Keep the 1-butene to ethylene concentration ratio at 3.25 g / g,
The first-stage polymerization was continuously carried out in a liquid-filled state under the conditions of a total pressure of 2.9 MPaG and an average residence time of 2.2 Hr. The hexane slurry containing the ethylene polymer obtained in the first polymerization vessel was flushed with unreacted gas in a depressurization tank, and then introduced into a second polymerization vessel having an internal volume of 545 liters to obtain a solid catalyst component and alkyl. Hexane 13 without adding aluminum
2 liters of ethylene at 80 ° C. while supplying 3 liter / Hr and discharging the contents of the polymerization vessel at a required rate.
Supply at a rate of g / Hr, ethylene concentration 0.80 wt
%, Hydrogen concentration ratio to ethylene 0.077 mol / mol
Kept at a total pressure of 2.0 MPaG, average residence time of 1.7 Hr
The second stage polymerization was carried out under the conditions of. The slurry from the second polymerization vessel was flushed with unreacted gas in a depressurization tank, and then separated and dried to obtain an ethylene polymer powder. <Production of Polyethylene Resin Composition> 0.005 parts by weight of α, α′-bis (t-butylperoxy) diisopropylbenzene as a radical generator is added to 100 parts by weight of the obtained ethylene polymer powder. Except for the above, pelletization was performed in the same manner as in Example 1. The MFR of the obtained polyethylene resin composition was 0.7 g / 10 minutes,
HLMFR is 51.2 g / 10 minutes, density is 950 kg /
m ³ , Charpy impact value is 11 kJ / m ² , ESCR is 1
00Hr, MS was 4.9 g, GPC molecular weight distribution (Mw / Mn) was 10.2, and the value of a in the linear regression equation Y = a × Log (X) + b obtained by GPCFTIR was −0.015. It was

Comparative Example 4 <Polymerization> Using the above catalyst component (1), ethylene concentration 0.80 wt%, hydrogen to ethylene concentration ratio 0.1.
0 mol / mol, 1-butene to ethylene concentration ratio 6.
Polymerization was continuously carried out by the same method as in Example 1 except that the amount was 13 g / g to obtain an ethylene polymer powder. <Production of Polyethylene Resin Composition> The powder of the ethylene polymer obtained in Example 1 was pelletized by the same method as in Example 1 except that the radical generator was not added. The obtained polyethylene resin composition has an MFR of 1.2 g / 10 minutes, an HLMFR of 29.9 g / 10 minutes,
Density is 935 kg / m ³ , Charpy impact value is 13 kJ
/ M ² , ESCR 250 Hr, MS 2.5 g, GP
Molecular weight distribution by C (Mw / Mn) is 3.3, GPCF
A linear regression equation Y = a × Log (X) obtained by TIR
The value of a at + b was 0.0084.

Comparative Example 5 <Polymerization> Polymerization was continuously carried out by the same method as in Example 5 except that the ethylene concentration in the second polymerization vessel was 0.85 wt% and the hydrogen concentration ratio to ethylene was 0.069 mol / mol. An ethylene polymer powder was obtained. <Production of Polyethylene Resin Composition> The obtained ethylene polymer powder was pelletized in the same manner as in Example 1 except that the radical generator was not added.
The MFR of the obtained polyethylene resin composition was 0.6 g /
10 minutes, HLMFR is 43.1 g / 10 minutes, density is 95
0 kg / m ³ , Charpy impact value is 16 kJ / m ² , ES
CR is 1000hr or more, MS is 4.5g, molecular weight distribution (Mw / Mn) by GPC is 9.9, GPCFTIR
The value of a in the linear regression equation Y = a × Log (X) + b obtained by the above was 0.0058.

[0083]

According to the present invention, a polyethylene resin having excellent mechanical properties represented by ESCR and impact strength by controlling the composition distribution and excellent moldability represented by melt tension by addition of a radical generator. The composition can be newly obtained. Among them, a polyethylene resin composition having high rigidity and ESCR and excellent in moldability can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a distribution of branching degree with respect to a molecular weight obtained by GPCFTIR in Example 1 and Comparative Example 1.

Claims (3)

[Claims] 1. A radical generator 0.001 to 0.05 part by weight based on 100 parts by weight of an ethylene-based polymer comprising ethylene and an α-olefin having 3 to 12 carbon atoms, which is produced using a Ziegler-Natta catalyst. A polyethylene resin composition obtained by adding the following, wherein the polyethylene resin composition satisfies the following a) to d). a) Melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g is 0.1 to 10 g / 10 minutes, and b) Weight average molecular weight (Mw) determined by GPC (gel permeation chromatography). The number average molecular weight (Mn) ratio (Mw / Mn) is 3 to 20, and c) it is obtained by GPCFTIR (gel permeation chromatography Fourier transform infrared spectrometer) 1
The molecular weight existing between x10 ^{4 and} 1x10 ⁶ was fractionated into at least 20 points, and the logarithm of each fractionated molecular weight (X) Lo
A linear regression equation with the number of branches (Y) contained in each component obtained for g (X) Y = a × Log (X) + b
The value of a is positive, and d) the melt tension (MS) satisfies the formula (1) Log (MS) ≧ −0.907 × Log (MFR) +0.52 (1). 2. The radical generator according to claim 1 is an organic peroxide or an azo compound having a one-minute half-life temperature of 100 ° C. or higher, and the addition amount thereof is 100 parts by weight of the ethylene polymer. It is 0.001-0.05 weight part, The polyethylene resin composition of Claim 1 characterized by the above-mentioned. 3. A radical generator, based on 100 parts by weight of the ethylene polymer according to claim 1 or 2.
3. An organic peroxide or an azo compound having a one-minute half-life temperature of 100 [deg.] C. or higher is added in an amount of 0.001 to 0.05 part by weight, and the mixture is melt-kneaded and kneaded. A method for producing the polyethylene resin composition according to claim 1.