JPH07126316A - Production of ethylene copolymer - Google Patents

Abstract

PURPOSE:To obtain an ethylene copolymer for hollow molding which has an excellent balance between rigidity and environmental-stress cracking resistance(ESCR) through two-stage copolymerization using a Ziegler catalyst by adding a specific compound to the second-stage polymerization zone. CONSTITUTION:An ethylene copolymer is produced by the two-stage copolymerization of ethylene and an alpha-olefin using a Ziegler catalyst. High-mol. components are produced in the first polymerization zone, and low-mol. components are then produced in the second polymerization zone in the presence of a compound (a) represented by the formula (wherein R<1> to R<4> each independently is hydrogen, an alkyl, an aryl, an aralkyl, an alkoxy, etc., and (n) is an integer of 1-10). The compound (a) is fed in such an amount that the molar ratio of the compound (a) to the Ti atoms contained in the catalyst present in the second-stage polymerizer is about 0.1-50.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an ethylene copolymer. More specifically, it relates to a method for producing an ethylene-based copolymer for blow molding, which has an excellent balance between rigidity and environmental stress crack resistance (ESCR).

[0002]

2. Description of the Related Art In the field of blow molding such as blow containers, an ethylene copolymer having a high molecular weight and a wide molecular weight distribution is required. In particular, it is desired that the product after molding has an excellent balance between rigidity and environmental stress crack resistance (ESCR). Up to now, there have been many proposals for a method of producing an ethylene copolymer for blow molding having a wide molecular weight distribution by two-step polymerization. Particularly, there is a method disclosed in Japanese Patent Publication No. 3-18645. This is a method in which a continuous two-stage polymerization is carried out using an easily volatile hydrocarbon solvent such as propane or isobutane to produce a high-molecular weight component in the first stage and a low-molecular weight component in the second stage. When adjusting the molecular weight with hydrogen, the transition from the first stage to the second stage does not require an intermediate hydrogen flash tank, which is highly desirable from the viewpoint of productivity.

[0003]

However, the above-mentioned Japanese Patent Publication No. 3-
When the high molecular weight component is produced in the first stage and the low molecular weight component is produced in the second stage as in the production method described in 18645, it is supplied in the first stage in order to improve the environmental stress crack resistance (ESCR). Among the α-olefins, the unreacted part that has not been copolymerized with ethylene flows into the second stage as it is. The α-olefin flowing into the second stage is copolymerized with ethylene to reduce the density of low molecular weight components, and thus the density of the ethylene-based copolymer produced by the two-stage polymerization. Therefore, when the same ESCR is used for comparison, the rigidity of the product after molding becomes low as compared with the case where the α-olefin does not flow into the second stage and the density does not decrease. The balance between rigidity and ESCR is worse than the original performance.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of the above problems, the present inventors have found that the rigidity and the environmental cracking resistance (E
It was found that an ethylene copolymer for blow molding having an excellent SCR) balance can be produced, and the present invention has been completed. That is, the present invention is a two-stage polymerization in which ethylene and α-olefin are polymerized with a high molecular weight component in a first polymerization zone and a low molecular weight component is polymerized in a second polymerization zone using a Ziegler type catalyst. In producing the copolymer, the general formula in the second polymerization zone

[Chemical 4] (In the formula, R ^{1 to} R ⁴ may be the same or different and each is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a carbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group or a halogen. Which is any of the atoms, and n is an integer of 1 to 10.) in the method for producing an ethylene-based copolymer.

The present invention will be specifically described below. Solid catalyst component The solid catalyst used in the production of the ethylene-based copolymer of the present invention.
At least magnesium, titanium and
A solid catalyst component containing halogen is used. example
For example, JP-A-53-78287 and JP-A-53-13208
2, JP-A-54-75491, JP-A-54-8119
0, JP-A-55-3459, JP-A-57-20541
0, JP-A-58-149906, JP-A-58-2251
05 etc. can be used.

Specifically, there are solid catalyst components (A) and solid catalyst components (B). As the solid catalyst component (A), (A)-(1) (a) aluminum trihalide,
(A)-(2) a tetravalent titanium compound having at least one halogen atom in the co-ground product obtained by co-grounding (b) an organic compound having a Si-O bond and (c) magnesium alcoholate; Is a solid catalyst component obtained by contacting in a liquid phase. Aluminum trihalides are anhydrous and include aluminum trichloride, aluminum tribromide, and aluminum trifluoride.
Aluminum trichloride is particularly preferable. The aluminum trihalide may be in the form of powder or particles. Si-
A typical organic compound having an O bond is represented by the general formula: Si (OR ¹¹ ) _p R ¹² _q (I) R ¹³ (R ¹⁴ ₂ SiO) _r SiR ¹⁵ ₂ (II) (R ¹⁶ ₂ SiO) _s (III ). In the formula, R ¹¹ , R ¹² and R ¹⁶ may be the same or different and are a hydrocarbon group selected from the group consisting of an alkyl group having at most 20 carbon atoms, a cycloalkyl group, an aryl group and an aralkyl group. (These may be unsaturated, may be substituted with a halogen atom or an alkoxy group having at most 20 carbon atoms, and may have an epoxy ring such as a glycidyl group) (R ¹² is a hydrogen atom or a halogen atom). Atom, R ¹⁶ may be a hydrogen atom), R ¹³ , R ¹⁴ and R ¹⁵
May be the same or different, are the above hydrocarbon groups (which may be unsaturated or substituted) or halogen atoms, p + q is 4 (where p ≠ 0), and r is 1 to 1000. Is an integer and s is 2 to 1000
Is an integer.

Typical compounds represented by the formula (I) include tetramethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, tetraethoxysilane, triethoxyethylsilane, diethoxydiethylsilane, ethoxytriethylsilane, Tetrapropoxysilane, dipropoxydipropylsilane, tetraisopropoxysilane, diisopropoxydiisopropylsilane, dimethoxydiethylsilane, diethoxydibutylsilane, tetra-n-butoxysilane, di-n-butoxy-di-n-butylsilane, tetrasec-butoxy Silane, tetrahexoxysilane, tetraoctoxysilane, tetraphenoxysilane, tetracresylsilane, diphenyldiethoxysilane, diphenyldimethoxysilane, trimethoxychloro Orchids, dimethoxy dichlorosilane,
Dimethoxydibromosilane, triethoxychlorosilane, diethoxydibromosilane, dibutoxydichlorosilane, dicyclopentoxydiethylsilane, diethoxydiphenylsilane, 3,5-dimethylphenoxytrimethylsilane, methylphenyl-bis (2-chloroethoxy) silane , Dimethoxydibenzylsilane, tri-n-propylallyloxysilane, allyltris (2-chloroethoxy) silane, trimethoxy-3-ethoxypropylsilane, vinyl (tributoxy) silane and 3-
Examples thereof include (glycidoxy) propyltrimethoxysilane.

Typical compounds represented by the formula (II) include hexamethyldisiloxane, octamethyltrisiloxane, tetracosamethylundecasiloxane, 8-hydroheptamethyltrisiloxane and hexaphenyldisiloxane. , Hexacyclohexyldisiloxane, 1,8-dimethyldisiloxane, hexaethyldisiloxane, octaethyltrisiloxane, hexapropyldisiloxane, 1,3-dichlorotetramethyldisiloxane, 1,3-bis (p-phenoxydiphenyl)
-1,3-dimethyl-1,3-diphenyldisiloxane, 1,3-diallyltetramethyldisiloxane, 1,
3-dibenzyltetramethyldisiloxane, 2,2
Examples include 4,4-tetraphenyl-2,4-disilane-1-oxacyclopentane, 1,1,3,3-tetramethyldisiloxane, and hexachlorodisiloxane.

Further, as typical compounds represented by the formula (III), 1,3,5-trimethylcyclotrisiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and pentamethylchlorocyclotrisiloxane. , 1,3,5-trimethyltriphenylcyclotrisiloxane, hexaphenylcyclotrisiloxane, 1,3,5-tribenzyltrimethylcyclotrisiloxane and 1,3,5-triallyltrimethylcyclotrisiloxane. Among these compounds having a Si—O bond, compounds in which R ¹¹ and R ¹² in the above formula (I) are each represented by an alkyl group, a phenyl group or an aralkyl group having at most 8 carbon atoms are preferable. Further, in the formula (II), it is preferable that R ¹³ , R ¹⁴ and R ¹⁵ are each represented by an alkyl group having at most 4 carbon atoms, a phenyl group or a halogen atom, and further, those having r of 4 or less. preferable. Moreover, the above (III)
In the formula, R ¹⁶ is preferably a hydrogen atom, an alkyl group having 4 or less carbon atoms, a phenyl group or a vinyl group, and more preferably s is 10 or less. Examples of these compounds having a suitable Si-O bond include tetramethoxysilane, tetraethoxysilane, tetracresylsilane, hexamethyldisiloxane, diethoxydiphenylsilane, dimethoxydiphenylsilane and vinyl (tributoxy) silane. .

As the magnesium alcoholate, a typical one is represented by the following formula (IV). Mg (OR ¹⁷ ) ₂ (IV) In the formula (IV), R ¹⁷ is a hydrocarbon group having at most 8 carbon atoms selected from the group consisting of an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group. . Typical of these magnesium alcoholates are magnesium methylate, magnesium ethylate, magnesium propylate, magnesium butyrate, magnesium hexylate, magnesium phenolate, magnesium cyclohexanolate, magnesium benzyl alcoholate and magnesium crelate. Examples include zolate. Among these magnesium alcoholates, those in which R ¹⁷ in the above formula (IV) is represented by an alkyl group or a phenyl group having at most 3 carbon atoms are preferable. These suitable magnesium alcoholates include magnesium methylate, magnesium ethylate and magnesium phenolate.

In preparing the co-ground product of (A)-(1) above, aluminum trihalide and Si-based on the magnesium alcoholate per mole are used.
The addition ratio of the compound having an O bond is generally 0.02 to 1.0 mol, and particularly 0.05 to 0.20.
Molar is preferred. Further, the ratio of aluminum atoms of aluminum halide to silicon atoms of the compound having a Si—O bond is important. The ratio is preferably 0.25 to 4, and particularly preferably 0.5 to 2. As a method of co-milling, a method generally used by using a mill such as a ball mill, a vibrating ball mill, an impact mill and a colloid mill which are generally used in producing this kind of solid catalyst component is applied. Just do it. The co-grinding temperature may be room temperature, but when the heat generation is large, it may be cooled. The pulverization is performed in a dry inert gas (for example, nitrogen, argon) atmosphere. The time required for co-pulverization cannot be unconditionally specified by the type and capacity of the pulverizer used and the filling amount, type and proportion of the pulverized product, but the particle size and particle size distribution of the co-pulverized product are uniform. The grinding time should be selected to the extent that Therefore, it is generally 10 minutes or more, but 2
Even if co-milled for 0 hours or more, the effect cannot be expected to be further improved, and the yield of the co-milled product may be rather lowered. The co-ground product thus obtained is
It is a complex containing aluminum, silicon and magnesium. The average particle size of the co-ground product thus obtained is usually 50-200 microns and the specific surface area is 2
It is 0 to 200 m ² / g.

The solid catalyst component (A) of the present invention is obtained by bringing the co-ground product obtained as described above into contact with the titanium compound in the liquid phase. In this case, it may be carried out in the presence of a hydrocarbon solvent, or when the titanium compound is in a liquid state, it may be carried out as it is without a solvent. The titanium-based compound used for producing the solid catalyst component is a tetravalent titanium compound having at least one halogen atom, and its general formula is represented by the following formula (V). TiX _t (OR ¹⁸ ) _u (NR ¹⁹ R ²⁰ ) _v (OCOR ²¹ ) _w (V) (V) In the formula, X is a chlorine atom, a bromine atom or an iodine atom, and R ¹⁸ , R ¹⁹ , R ²⁰ and R ²¹ is an aliphatic, alicyclic or aromatic hydrocarbon having at most 12 carbon atoms, t is a number from 1 to 4 and u, v and w are 0.
To 3 and t + u + v + w is 4. Typical examples of titanium compounds include titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, methoxytitanium trichloride,
Dimethoxy titanium dichloride, trimethoxy titanium chloride, ethoxy titanium trichloride, diethoxy titanium dichloride, triethoxy titanium chloride,
Examples thereof include propoxy titanium trichloride, butoxy titanium trichloride, dimethylamini titanium trichloride, bis (dimethylamino) titanium dichloride, diethylamino titanium trichloride, titanium propionate trichloride and titanium benzoate trichloride. Among them, in the formula (V), v and w are 0, R ¹⁸ is an alkyl group having at most 6 carbon atoms, and t is 3 or u is 0 (that is, t
4) is preferable, and titanium tetrachloride, methoxytitanium trichloride, ethoxytitanium trichloride and butoxytitanium trichloride are particularly preferable.

In producing the solid catalyst component, it is not always necessary to carry out in the presence of a hydrocarbon solvent, but when carried out in the presence of a hydrocarbon solvent, the hydrocarbon solvent used is 0 ° C to 140 ° C. And those which are liquid are preferred. Typical examples are aliphatic hydrocarbons (eg, isobutane, n-pentane, n-hexane, n-heptane, paraffin), alicyclic hydrocarbons (eg, cyclohexane, methylcyclohexane, dimethylcyclohexane) and aromatic hydrocarbons. (Eg, benzene, toluene, xylene). As the proportion of the co-milled product and the titanium-based compound to be brought into contact with each other, an appropriate condition may be selected so that the amount of titanium atoms supported on the co-milled product is generally 0.5 to 10% by weight. Therefore, the ratio of the titanium compound to 1 atom of magnesium in the co-ground product is 0.5 to 50 mol, preferably 0.5 to 40 mol, and particularly preferably 1.0 to 20 mol. The contact temperature is usually room temperature to 150 ° C., particularly preferably room temperature to 130 ° C. If the contact is made at room temperature or lower, the contact is insufficient. On the other hand, at 150 ° C or higher, a satisfactory solid catalyst component cannot be obtained. The contact time is generally 10 minutes to 5 hours, but it is particularly preferable to contact for 10 minutes to 3 hours from the viewpoint of polymerization activity. When the contact time is 10 minutes or less, the contact is insufficient. On the other hand, even if they are contacted for 5 hours or more, the contact does not proceed further, and the solid catalyst component obtained may be deactivated. To carry out this contact in the presence of the hydrocarbon solvent, the hydrocarbon solvent is at most 10 parts by weight per 1 part by weight of the co-ground product, depending on the solubility of the titanium compound.

The contact product obtained as described above contains an unreacted titanium compound in addition to the solid catalyst component. The solid catalyst component of the present invention is obtained by purifying this contact product. In order to carry out this purification, the supernatant liquid is extracted by a gradient method or a filtration method using the hydrocarbon solvent used at the time of contact or another hydrocarbon solvent (particularly, one having a relatively low boiling point is preferable), and the washing solution is washed. It is desirable to repeat the wash until no halogen is present in it. It may be washed with the above hydrocarbon solvent, and the slurry containing the obtained solid catalyst component (however, substantially free of unreacted titanium-based compound) is supplied to the polymerization vessel described later. Is also possible. It is also possible to remove the hydrocarbon solvent used for washing under reduced pressure and then mud-feed it to the polymerization vessel as a solid component.

The catalyst system used in the present invention is obtained from the solid catalyst component obtained as above and an organoaluminum compound. The organoaluminum compound is
The general formula is represented by the following formulas [(VI) and (VII)]. AlR ²² R ²³ R ²⁴ (VI) R ²⁵ R ²⁶ Al-O-AlR ²⁷ R ²⁸ (VII) In the formula (VI), R ²² , R ²³ and R ²⁴ may be the same or different and have at most carbon atoms. Twelve aliphatic, alicyclic or aromatic hydrocarbon groups, halogen atoms or hydrogen atoms, at least one of which is the above hydrocarbon group, and when a halogen atom is contained, the halogen atom is It is one. Further, in the formula (VII), R ²⁵ , R
²⁶ , R ²⁷ and R ²⁸ are the aforementioned hydrocarbon groups. Among the organoaluminum compounds represented by the formula (VI), typical ones include trialkylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum and trioctylaluminum, trialkylaluminums, diethylaluminum hydride and diisobutylaluminum hydride. Examples thereof include dialkyl aluminum hydrides and dialkyl aluminum halogenides such as diethyl aluminum chloride. Further, among the organoaluminum compounds represented by the formula (VII), typical ones include alkylalumoxanes such as tetraethyl dialumoxane and tetrabutyl dialumoxane. Of these organoaluminum compounds, trialkylaluminums are preferable, and trialkylaluminums having an alkyl group having at most 6 carbon atoms (eg, triethylaluminum, triisobutylaluminum) are preferable. The aluminum halide, silicon compound and magnesium alcoholate, titanium compound and the organoaluminum compound used for obtaining the catalyst system used in the present invention may each be used alone or in combination of two or more. You may.

As the solid catalyst component (B), (B)-(1) (a) aluminum trihalide,
Obtained by contacting (b)-(2) a tetravalent titanium compound having at least one halogen atom with a solid product of (b) an organic compound having a Si-O bond and (c) a magnesium alcoholate. Solid catalyst component. As the aluminum trihalide, the same aluminum halide as that used for producing the solid catalyst component (A) is used, and aluminum chloride is particularly preferable. As the silicon compound having a Si—O bond, the same silicon compound as used in the production of the solid catalyst component (A) is used, and particularly tetramethoxysilane, tetraethoxysilane, tetracresylsilane, hexamethyldihexadiene. Examples include siloxane and diethoxydimethylsilane. As the magnesium alcoholate, the same magnesium compound as that used for the production of the solid catalyst component (A) is used, and particularly magnesium methoxide, magnesium ethoxide and magnesium phenoxide are mentioned.

In producing the solid catalyst component (B),
The reaction ratio of aluminum halide to 1 mol of the magnesium alcoholate is generally 0.5 to 10
It is a mol, and particularly preferably 0.5 to 5 mol. When the reaction ratio of aluminum halide is 0.5 mol or less with respect to 1 mol of magnesium alcoholate, the polymerization activity of the obtained catalyst system is low, while when it is 10 mol or more, the bulk specific gravity of the produced ethylene polymer is 0. .18 or less, thus reducing productivity. The reaction ratio of the silicon compound to 1 mol of magnesium alcoholate is generally 0.5 to 10 mol, and particularly preferably 0.5 to 5 mol. A particularly important factor is the reaction ratio between the aluminum halide and the silicon compound. As described later, when a reaction product of the aluminum halide and the silicon compound is produced in advance, 1 mol of the halogenated compound with respect to the silicon compound is used. The reaction ratio of aluminum is usually 0.25 to 4 mol, and 0.5 to 1.5 mol is particularly preferable. Even if 1 mol of a silicon-based compound is reacted with 0.25 mol or less or 4 mol or more of an aluminum halide, the polymerization activity of the resulting catalyst system is reduced, and the bulk specific gravity of the resulting polymer is reduced, which is desirable. Absent.

As a method for producing a solid product, a method of simultaneously reacting the above-mentioned aluminum halide, silicon compound and magnesium alcoholate [hereinafter referred to as "method (a)"] and aluminum halide in advance There are two methods: a method of reacting with a silicon-based compound, and then a reaction product obtained with magnesium alcoholate [hereinafter referred to as "method (b)"]. The aluminum halides, magnesium alcoholates and silicon-based compounds used to produce the solid product are all hygroscopic and are susceptible to hydrolysis even in the presence of slight moisture, making them dry Active gas (eg nitrogen, argon)
It is important to react under the atmosphere of. Furthermore, this reaction is carried out in an inert organic solvent which is normally a liquid at room temperature. Typical examples of the organic solvent include aliphatic hydrocarbons (for example, n-hexane and n-heptane), alicyclic hydrocarbons (for example, cyclohexane and methylcyclohexane) and aromatic hydrocarbons (for example, benzene and toluene). And halides of these hydrocarbons (eg carbon tetrachloride, trichloroethylene) and mixtures thereof, but in particular:
Those having a boiling point of 50 to 200 ° C. are preferable, and benzene and toluene are particularly preferable. Needless to say, a trace amount of water does not exist in these organic solvents. When the aluminum halide and the silicon-based compound are reacted in the presence of benzene or toluene,
The reaction is exothermic, and a product completely solubilized in the above organic solvent is obtained. At that time, the reaction ratio of the silicon-based compound to 1 mol of aluminum halide was 0.2.
If it is not in the range of 5 to 4.0 mol, the reaction product may become non-uniform in the above hydrocarbon solvent, and the reaction with the magnesium alcoholate (solid) may not proceed smoothly.

Method (a) is a method in which aluminum halide, magnesium alcoholate and silicon compound are simultaneously added to the solvent and reacted (heated). The reaction temperature in this reaction is the mutual reaction ratio of aluminum halide, magnesium alcoholate and silicon compound, their type, the type of the inert organic solvent used, the ratio of the silicon compound to the inert organic solvent and other reaction conditions. Generally, it is room temperature (about 25 ° C.) to 150 ° C., though it depends on the temperature. The reaction time varies depending on the reaction conditions and the reaction temperature, but is generally 10 minutes to 2 hours. In particular,
Considering both the above reaction temperature and reaction time, 50
The desired product (a complex compound containing aluminum, silicon and magnesium) can be obtained by reacting in the temperature range of -100 ° C for 30 minutes to 1.5 hours.

In the method (b), first, an aluminum halide is reacted with a silicon compound. The reaction temperature in this reaction includes the reaction ratio between the aluminum halide and the silicon compound, the type of the aluminum halide and the silicon compound, the type of the inert organic solvent used, the ratio of the silicon compound to the inert organic solvent, and other factors. Although it depends on the reaction conditions, it is generally room temperature (about 25
C.) to 150.degree. C., preferably room temperature to 100.degree. When the reaction temperature is below room temperature, the reaction rate is slow,
If the reaction is carried out at a temperature of not lower than 0 ° C., the bulk specific gravity of the resulting polymer tends to decrease when polymerized in the presence of the finally obtained catalyst system, which is not desirable. The reaction time varies depending on the reaction conditions and the reaction temperature, but generally 10 minutes or more is sufficient to achieve the purpose. From the above, considering both the reaction temperature and the reaction time, it is preferable to carry out the reaction at a temperature of room temperature (about 25 ° C.) to 80 ° C. for 15 minutes to 1 hour. In this reaction, the reaction system is heterogeneous (suspension) at the beginning of the reaction, but as the reaction proceeds, it becomes a discolored and homogeneous solution.

By reacting the reaction product obtained by the above method with the magnesium alcoholate, a solid product can be produced by the method (b). The reaction temperature in this reaction is, for example, the reaction ratio between the reaction product and magnesium alcoholate, the type of magnesium alcoholate, the production conditions for the reaction product, the type of inert hydrocarbon used, and the ratio of magnesium alcoholate to inert hydrocarbon. Although it depends on the reaction conditions, it is generally from room temperature to 150 ° C.
When the reaction temperature is lower than room temperature, the formation of a complex compound of aluminum, silicon and magnesium (solid product) is insufficient. On the other hand, if the reaction is carried out at 150 ° C. or higher, a side reaction may occur, which is not desirable. Further, the reaction time is generally 10 minutes to 3 hours, though it varies depending on the above reaction conditions and reaction temperature. From the above, considering both the reaction temperature and the reaction time, 50 to 50
It is preferred to react at a temperature of 100 ° C. for 30 minutes to 1.5 hours.

After the reaction by the above method (a) or method (b) is completed, the hydrocarbon solvent used in the reaction or another hydrocarbon (particularly, n-hexane and n-heptane, which have a relatively low boiling point). The supernatant is withdrawn (preferably two or more times), and the solid product is washed several times with the above hydrocarbon solvent (may be another hydrocarbon). Of the methods (a) and (b), the method (b) is preferable in terms of polymerization activity of the resulting catalyst system. The solid product purified by the above method is a powdery solid product, although the color varies depending on the type of silicon compound. Analysis reveals a complex compound containing aluminum, silicon and magnesium. The solid catalyst component (B) can be produced by reacting the purified product of the solid product obtained by the above method with the titanium compound described below.

As the titanium-based compound used for producing the solid catalyst component (B), the same titanium-based compound as used for the production of the solid catalyst component (A) is used, especially titanium tetrachloride, Methoxytitanium trichloride,
Ethoxytitanium trichloride and butoxytitanium trichloride are preferred. Although the reaction rate of the solid product containing aluminum, silicon and magnesium and the titanium-based compound varies depending on the content ratio of magnesium in the solid product, the solid-state product can generally be a titanium-based compound. The reaction amount of the titanium compound per one atom of magnesium in the solid product is usually in the range of 0.1 to 200 mol (preferably 0.2 to 100 mol) in the minimum required amount to be supported. However, it may vary depending on the reaction temperature, concentration, and time. Appropriate conditions may be selected such that the amount of titanium atoms supported on the solid product (composite carrier) containing aluminum, silicon and magnesium is generally 1 to 10% by weight.

The solid catalyst component (B) is produced by mixing the solid product and the titanium compound in the inert hydrocarbon solvent used for producing the solid product or in the absence of the solvent. It can be obtained by reacting. The reaction temperature in this reaction is the reaction ratio of the titanium-based compound to magnesium in the solid product, the types of the solid product and the titanium-based compound, the use or non-use of an inert hydrocarbon solvent, and the inert carbon when used. Although it depends on the reaction conditions such as the type of the hydrogen fluoride solvent and the ratio of the solid product to the inert hydrocarbon solvent, it is generally room temperature to 150 ° C, and particularly preferably 50 to 140 ° C. If the reaction is performed at room temperature or lower, the reaction is insufficient. On the other hand, even if the reaction is carried out at a reaction temperature of 150 ° C. or higher, the intended product can be obtained, but it is not necessary. The reaction time varies depending on the reaction conditions and the reaction temperature, but is usually 10 minutes to 2 hours. When the reaction time is 10 minutes or less, the reaction is insufficient. Further, even if the reaction is carried out for 2 hours or more, the reaction does not proceed further and the obtained catalyst may be deactivated. From the above, considering both the reaction temperature and the reaction time, 10 at a temperature of 50 to 140 ° C.
It is preferable to carry out the reaction for a minute to 2 hours.

The solid component obtained by the above method is generally purified by the following method. That is, for the mixture of the solid component and the unreacted material, the hydrocarbon solvent used in the reaction or another hydrocarbon solvent (particularly, one having a relatively low boiling point is preferably used), and the supernatant is decanted or filtered. It may be washed with the above hydrocarbon solvent until the presence of the titanium-based compound in the washing liquid is no longer observed, and the slurry containing the obtained solid component (however, unreacted titanium-based compound is used). It is also possible to feed (comprising substantially no compound) to the polymerization vessel described later. Alternatively, the hydrocarbon solvent used for washing may be removed under reduced pressure and then supplied to the polymerization vessel as a solid component.

The catalyst system used in the present invention is obtained from the solid catalyst component obtained as above and an organoaluminum compound. As the organoaluminum compound used in the polymerization using the present solid catalyst component (B), the same compound as the organoaluminum compound used in the polymerization using the solid catalyst component (A) is used, and especially trialkylaluminum is A trialkylaluminum having an alkyl group with at most 6 carbon atoms (eg, triethylaluminum, triisobutylaluminum) is particularly preferable. In obtaining the solid catalyst component (B) used in the present invention, the aluminum halide, silicon compound and magnesium alcoholate used for producing the solid product, and the solid used for producing the solid component The product, the titanium-based compound and the organoaluminum compound may be used alone or in combination of two or more.

Copolymerization of ethylene and α-olefin is carried out at a temperature of 50 to 100 ° C. in a hydrocarbon solvent using the catalyst system as described above. Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, hexane and heptane, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. From the treatment, an easily volatile hydrocarbon solvent, propane, n-butane, isobutane, isopentane, n-pentane and the like are preferable. The α-olefin as a comonomer used in the copolymerization is selected from a chain or branched α-olefin having 5 or more carbon atoms. For example, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, dodecene-1, 4-methylpentene-1, and mixtures thereof.

In blow molding applications, high resistance to environmental stress cracking is required. As a result of diligent studies on the molecular structure and morphological structure from which the environmental stress crack resistance is exhibited, a copolymer of ethylene and an α-olefin having 5 or more carbon atoms is required for producing a high molecular weight component. It was found that the α-olefin having 4 or less carbon atoms had insufficient resistance to environmental stress cracking. The comonomer content is usually in the range of 0.2 to 5% by weight.
The polymerization reaction is carried out in two steps in a single reactor or in a plurality of reactors, and when a plurality of reactors are used, the reaction mixture obtained by the polymerization in the reaction zone in the first stage is continuously added to the second reactor. The reaction zone is fed continuously. The transfer from the reaction zone of the first stage to the reaction zone of the second stage is carried out through a connecting pipe, and is carried out by a differential pressure due to continuous discharge of the polymerization reaction mixture from the reaction zone of the second stage. When carrying out multi-stage polymerization using an easily volatile hydrocarbon solvent, the high-molecular weight component formed under conditions of low hydrogen concentration is the first stage, and the low-molecular weight component under conditions of high hydrogen concentration is the second stage. It is necessary for the process to polymerize in stages.

When industrially continuously producing by a two-step polymerization process, the polymerization specific activity in two polymerization zones (solid catalyst component, polymerization time, amount of polymer produced per ethylene partial pressure is R _sp From the ideal, it is desirable that they are the same, but for the intended purpose of broadening the molecular weight distribution, the specific activity R _sp , _L that produces a high molecular weight component and the specific activity R _sp , _H that produces a low molecular weight component It is ideal that the activity ratios R _sp , _L / R _sp , _H with Otherwise, a value as close as possible is desirable. If it is close to 1, it is sufficient to use a reactor having the same monomer concentration and the same residence time in each polymerization zone, and a volume ratio in which the ratio is not so different according to the production amount ratio.
When R _sp and _H are extremely lower than R _sp and _L , it is necessary to make a difference in volume ratio to cover the decrease in activity with another design or condition. Further, when the absolute values of R _sp and _H are low, the catalyst residue is large, which is not suitable for the deashing-free process. Also in the process, when R _sp and _H are low, it is possible to increase the catalytic efficiency (productivity) by increasing the ethylene concentration and the residence time, but under high hydrogen concentration conditions, when the monomer concentration is increased, the hydrogen The concentration also increases,
Naturally, there is a disadvantage that the operating pressure also rises. In view of such problems, the catalyst system applied to the present invention is preferably a carrier-supported catalyst obtained by treating a magnesium compound with a highly active Ziegler type catalyst containing a transition metal.
The specific activity (R _sp , _H ) of the catalyst for producing a relatively low molecular weight ethylene polymer having [η] = 1 is 800 g / g · hr · k.
The specific activity (R _sp , _L ) of the catalyst which forms a relatively high molecular weight polymer of g / cm ² or more and [η] ≧ 2 and the activity ratio of R _sp , _H are 1 <R _sp , _The catalyst is not particularly limited as long as it is a high activity catalyst satisfying the range of _L / R _sp , _H <3,
More preferred are the above catalyst systems.

Further, when a polymer mixture is produced by using the low molecular weight component in the first stage and the high molecular weight component in the second stage, for example, when the above catalyst system is used, R _sp , _L / R _sp , _H However, when the reverse order is applied, that is, when a high molecular weight component is prepared in the first stage and a low molecular weight component is prepared in the second stage, R _sp , _L / R _sp , _H = 1 It was found that the activity ratio in each stage was very close to 1 in each stage. From both sides, it is necessary to make a high molecular weight component in the first stage and a low molecular weight component in the second stage. In the step (a), ethylene having [η] ≧ 2.0 and α having 5 or more carbon atoms
The copolymerization reaction is carried out while adjusting the copolymer of the olefin and the weight ratio of the hydrogen concentration in the liquid phase to the ethylene concentration. The concentration ratio of hydrogen to ethylene in this liquid phase is
Generally, it is performed in the presence of hydrogen such that the concentration is 1.0 × 10 ⁻³ (weight ratio) or less. The ethylene-α-olefin copolymer produced in step (a) has a [η] a of 2.0 or more, that is, a weight average molecular weight of 12.8 × 10 5.
⁴ or more of the high molecular weight, the content of α- olefin in the copolymer, is generally 0.2 to 5% by weight, especially, 0.5
~ 2.5 wt% is preferred. In the step (b),
The concentration ratio of the hydrogen concentration to the ethylene concentration in the liquid phase of the ethylene polymer having [η] b in the range of 0.1 to 1.0 is 1
0 to 50 × 10 ^-3 (weight ratio), the following general formula

[Chemical 5] (In the formula, R ^{1 to} R ⁴ may be the same or different and each is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a carbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group or a halogen. It is achieved by adding a compound represented by any of the atoms, wherein n represents an integer of 1 to 10), and suppressing the copolymerization of α-olefin in the reaction mixture flowing from the step (a). To be done. Therefore, in the step (b), a relatively low molecular weight copolymer having a branching degree lower than the comonomer content of the copolymer of ethylene and α-olefin produced in the step (a) is produced. (A)
Polymerization is performed in each reaction step so that the proportion of the high molecular weight copolymer in the step and the low molecular weight polymer in the step (b) in the total polymer mixture are 30 to 70% by weight and 70 to 30% by weight, respectively. . The steps (a) and (b) may be carried out batchwise, but it is preferable to carry out stepwise polymerization from the viewpoint of productivity.

In the present invention, the intrinsic viscosity [η] is 130
Η, represents the intrinsic viscosity in tetralin solvent, [η] =
The viscosity average molecular weight Mv is calculated using a viscosity equation of 4.71 × 10 ⁻⁴ Mv ^0.71 . Since the weight additivity regarding the intrinsic viscosity is established, [η] _b of the ethylene polymer produced in the second reaction zone can be _calculated by the following equation. [Η] _b = {[η] _c −W _a [η] _a } / W _b where [η] _c is the intrinsic viscosity of the entire polymer, and W _a and W _b are (a) and (b) respectively. The weight fraction of the polymer in the step is shown, and W _a + W _b = 1.0. [Η] _a of the copolymer produced in the step (a) has an intrinsic viscosity of 2 or more and 6.2 or less, and [η] _b of the low molecular weight polymer produced in the step (b) is 0. A molecular weight in the range of more than 0.1 and less than 1.0 is selected. [Η] in the above molecular weight range
_a, [eta] copolymer (a) step of _b, but make at step (b), on the combination, the ratio of the constituent molecules weight i.e. _{[η] a / [η]} b 4.5~20. It is necessary to select the range of 0. Further, from the viewpoint of impact resistance and molding processability, it is preferable that the molecular weight [η] _{c of} all copolymers is in the range of 1.0 to 3.5. Further, the proportion of the step (a) and the step (b) is preferably 30 to 70% by weight in the whole polymer, but particularly the proportion of the high molecular weight (a) step is 40 to 60% by weight. It is preferable in terms of environmental stress cracking property and moldability.
The polymerization reaction is carried out at a temperature of 50 ° C to 100 ° C for 20 minutes to 1
0 hours, the pressure is 0.5 ~ depending on the solvent used.
It is carried out under a pressure of 100 Kg / cm ² . The reactor type may be a tank type (bessel type) or an annular type (loop type). In each stage of the reactor, the polymer concentration is generally 5 to 60% by weight, and preferably 35 to 55% by weight is suitable from the viewpoint of productivity. The polymer obtained as described above is then preferably kneaded. It is also possible to use a single-screw or twin-screw extruder or a continuous kneader.

The general formula added in step (b)

[Chemical 6] (In the formula, R ^{1 to} R ⁴ may be the same or different and each is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a carbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group or a halogen. The compound represented by any of the atoms, n is an integer of 1 to 10, is represented by the general formula:

[Chemical 7] (In the formula, R ⁵ and R ⁶ may be the same or different and each represents an alkyl group or an aryl group having 1 to 10 carbon atoms.)
And a general formula

[Chemical 8] (In the formula, R ^{7 to} R ¹⁰ are the same or different and each is a hydrogen atom or an alkyl group or an aryl group having 1 to 10 carbon atoms, and m is an integer of 1 to 10.) .

General formula

[Chemical 9] (In the formula, R ⁵ and R ⁶ may be the same or different and each represents an alkyl group or an aryl group having 1 to 10 carbon atoms.)
Examples of the compound represented by are methyl 4-methoxyacetoacetate, methyl 4-ethoxyacetoacetate, methyl 4-n-propoxyacetoacetate, methyl 4-isopropoxyacetoacetate, methyl 4-butoxyacetoacetate, and 4-hexoxyacetoacetic acid. Methyl, methyl 4-phenoxyacetoacetate, ethyl 4-methoxyacetoacetate, n-propyl 4-methoxyacetoacetate, isopropyl 4-methoxyacetoacetate, butyl 4-methoxyacetoacetate, hexyl 4-methoxyacetoacetate, 4-methoxyacetoacetate Phenyl acetate,
Ethyl 4-ethoxyacetoacetate, n-propyl 4-n-propoxyacetoacetate, isopyropyl 4-isopropoxyacetoacetate, butyl 4-butoxyacetoacetate, hexyl 4-hexoxyacetoacetate, phenyl 4-phenoxyacetoacetate, 4-n- Ethyl propoxyacetoacetate, 4
-Ethyl isopropoxyacetoacetate, ethyl 4-butoxyacetoacetate, ethyl 4-hexoxyacetoacetate, 4-
Ethyl phenoxyacetoacetate, n-propyl 4-ethoxyacetoacetate, isopropyl 4-ethoxyacetoacetate,
Butyl 4-ethoxyacetoacetate, hexyl 4-ethoxyacetoacetate, phenyl 4-ethoxyacetoacetate, methyl 4-methoxy-2-methylacetoacetate, 4-methoxy-
Methyl 2-ethylacetoacetate, 4-methoxy-2-n-
Methyl propylacetoacetate, methyl 4-methoxy-2-isopropylacetoacetate, methyl 4-methoxy-2-butylacetoacetate, methyl 4-methoxy-2-hexylacetoacetate, methyl 4-methoxy-2-phenylacetoacetate, 4- Methyl methoxy-2,2-dimethylacetoacetate, methyl 4-methoxy-2,2-diethylacetoacetate, methyl 4-methoxy-2,2-di-n-propylacetoacetate, 4-methoxy-2,2-diisopropylacetoacetate Methyl, methyl 4-methoxy-2,2-dibutylacetoacetate, methyl 4-methoxy-2,2-dihexylacetoacetate, methyl 4-methoxy-2,2-diphenylacetoacetate, particularly 4-methoxyacetoacetic acid Methyl is preferred.

In addition, the general formula

[Chemical 10] (In formula, R < ⁷ > -R < ¹⁰ > may be same or different and is a hydrogen atom or a C1-C10 alkyl group or aryl group, and m shows an integer of 1-10.). Compounds include 4-methoxy-2-butanone, 4-
Methoxy-2-pentanone, 4-methoxy-3-methyl-2-butanone, 4-methoxy-3-methyl-2-pentanone, 4-methoxy-4-methyl-2-pentanone,
4-methoxy-3,3-dimethyl-2-butanone, 4-
Methoxy-3,4-dimethyl-2-pentanone, 4-methoxy-3,3-dimethyl-2-pentanone, 4-methoxy-3,3,4-trimethyl-2-pentanone, 4-
Ethoxy-4-methyl-2-pentanone, 4-n-propoxy-4-methyl-2-pentanone, 4-isopropoxy-4-methyl-2-pentanone, 4-butoxy-4
-Methyl-2-pentanone, 4-hexoxy-4-methyl-2-pentanone, 4-phenoxy-4-methyl-2
-Pentanone, 5-methoxy-5-methyl-3-hexanone, 6-methoxy-6-methyl-4-heptanone, 7
-Methoxy-7-methyl-5-octanone, 8-methoxy-8-methyl-6-nonanone, 3-methoxy-3-methyl-1-phenyl-butanone, 4-ethoxy-3,3
-Dimethyl-2-butanone, 4-n-propoxy-3,
3-dimethyl-2-butanone, 4-isopropoxy-
3,3-dimethyl-2-butanone, 4-butoxy-3,
3-dimethyl-2-butanone, 4-hexoxy-3,3
-Dimethyl-2-butanone, 4-phenoxy-3,3-
Dimethyl-2-butanone, 5-methoxy-4,4-dimethyl-3-pentanone, 6-methoxy-5,5-dimethyl-4-hexanone, 7-methoxy-6,6-dimethyl-5-heptanone, 8- Methoxy-7,7-dimethyl-
6-octanone, 3-methoxy-2,2-dimethyl-1
-Phenyl-propanone is mentioned, and 4-methoxy-4-methyl-2-pentanone is particularly preferable.

The above compound added in the step (b) is diluted with an aliphatic hydrocarbon such as hexane or heptane or an alicyclic hydrocarbon such as cyclohexane or methylcyclohexane and supplied to the reactor in the step (b). . Although the concentration is arbitrary, it is supplied so that the molar ratio of the above compound to Ti atoms contained in the catalyst in the reactor of step (b) is 0.1 to 50, preferably 0.5 to 10. It The above compounds may be used alone or in combination of two or more.

[0036]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The method of physical property test is as follows. Polymer powder 65 mmφ, L / D = 26, full flight screw extruder (50 rpm, C ₁ = 160
℃, C ₂ = 200 ℃, C ₃ = 220 ℃, D = 210 ℃)
Physical properties were measured using a sample that was kneaded in and pelletized. The density was measured according to JIS-K-6760. For the rigidity, the flexural modulus measured according to JIS-K-7203 was used as the rigidity value. ESCR is JIS-K-67
ESCR the F ₅₀ value by BTL method measured according 60
The value of

Example 1 (1) Preparation of catalyst 20 L of anhydrous aluminum chloride 4.37 mol and diphenyldiethoxysilane 3.06 mol together with toluene 8 L
Into the reaction vessel of, and after reacting for 30 minutes at 60 ° C. with stirring, 8.75 mol of magnesium ethylate was added, and 9
After reacting at 0 ° C for 1.5 hours, the mixture was cooled to 40 ° C. The supernatant was taken out and washed several times with n-hexane, 2.5 L of titanium tetrachloride was added, and the reaction was carried out at 90 ° C for 1.5 hours. After cooling unreacted titanium tetrachloride to 40 ° C or lower, n-
The solid catalyst was washed with hexane and the dilution rate was reduced to 1/1000 or less. The Ti content in the solid catalyst is 8.5% by weight,
The Cl content was 48% by weight.

(2) Two-step polymerization 117 L / hr of dehydrated and purified isobutane and 1 part of triisobutylaluminum were introduced into a first-stage polymerization vessel having an internal volume of 200 L.
The supported catalyst was mixed with 5.09 at a rate of 75 mmol / hr.
While continuously feeding at a rate of g / hr and discharging the contents of the polymerizer at a required rate, ethylene was added at 21.
0 kg / hr and hexene-1 were supplied at a rate of 0.30 kg / hr, and the hydrogen concentration in the liquid phase was 0.15 × 10 ⁻³ wt.
%, Ethylene concentration 1.0 wt%, hydrogen to ethylene concentration ratio 0.15 × 10 ⁻³ (w / w), and hexene-1 to ethylene concentration ratio at 0.42 (w / w), and total pressure 41 kg
/ Cm ² , and the average residence time is 0.80 hr, the first stage copolymerization is continuously performed in a liquid-filled state. Isobutane slurry containing ethylene / hexene-1 copolymer produced by copolymerization (polymer concentration: 23% by weight, intrinsic viscosity of the polymer: 3.2, hexene content: 0.36% by weight, copolymer density: 0.952g / cm ³ ) as it is the internal volume of 400L
Was introduced into the second-stage polymerization reactor of No. 2 through a continuous tube having an inner diameter of 50 mm, and 55 L of isobutane was added without adding a catalyst.
hr, hydrogen, and further 4-methoxy-4-methyl-2-pentanone were supplied so that the molar ratio to titanium atoms in the catalyst in the second-stage polymerization reactor was 5, and the contents of the polymerization reactor were discharged at a required rate. However, at 90 ℃, ethylene 2
It was fed at a rate of 3.7 kg / hr and the ethylene concentration was 1.
20% by weight, hydrogen concentration ratio to ethylene is 15 × 10
^-3 (w / w), the total pressure is 41.0 kg / cm ² , and the residence time is 1.05 hr. The effluent from the second-stage polymerizer contained 3 parts of ethylene polymer mixture.
1% by weight, the intrinsic viscosity of the polymer was 1.6, and the density of the ethylene copolymer mixture was 0.9592 g / cm ³ . The production ratio of the first-stage and second-stage polymers is 47: 5.
3, the ethylene copolymer produced only in the second-stage polymerizer has an intrinsic viscosity of 0.18, a hexene-1 content of 0.03% by weight, and a density of 0.967 g / cm ³ . Equivalent to. The flexural modulus of this copolymer is 14900 kg.
f / cm ² , ESCR was 65 hr, and an ethylene-based copolymer having an excellent balance between rigidity and ESCR was obtained.

Example 2 Polymerization was carried out in the same manner as in Example 1 except that the compound added in the second stage was changed to methyl 4-methoxyacetoacetate. The results are shown in Table 1. Rigidity and ESCR
An ethylene-based copolymer having an excellent balance was obtained.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the compounds corresponding to Examples 1 and 2 were not added in the second stage. The results are shown in Table 1. The ESCR was good, but the rigidity was low.

Example 3 (1) Preparation of catalyst A commercially available magnesium ethylate (average) was put in a nitrogen atmosphere in a pot (crushing vessel) having an internal volume of 1 L containing about 700 porcelain balls having a diameter of 10 mm. Particle size 860 microns) 20
g (17.5 mmol), 1.66 g (12.5 mmol) of granular aluminum trichloride and 2.72 g (10 mmol) of diphenyldiethoxysilane were added. Using a vibrating ball mill, these were co-milled for 3 hours under the conditions of an amplitude of 6 mm and a frequency of 30 Hz / min. After co-milling, the contents were separated from the porcelain ball under a nitrogen atmosphere.
5 g and 20 of the co-ground product obtained as described above
ml n-heptane was added to a 200 ml three necked flask. With stirring, 10.4 ml of titanium tetrachloride was added dropwise at room temperature, the temperature of the reaction system was raised to 90 ° C., and stirring was continued for 90 minutes. Then, after cooling the reaction system, the supernatant was withdrawn and n-hexane was added. This operation was repeated 3 times. The obtained pale yellow solid was dried at 50 ° C. under reduced pressure for 6 hours. As a result, 7.2 g of solid was obtained. The Ti content in the solid catalyst was 11% by weight, and the Cl content was 59% by weight.

(2) Two-stage polymerization In a first-stage polymerization vessel having an internal volume of 200 L, 117 L / hr of dehydrated and purified isobutane and 1 L of triisobutylaluminum were used.
The supported catalyst was mixed with 5.09 at a rate of 75 mmol / hr.
While continuously feeding at a rate of g / hr and discharging the contents of the polymerizer at a required rate, ethylene was added at 21.
0 kg / hr and hexene-1 were supplied at a rate of 0.45 kg / hr, and the hydrogen concentration in the liquid phase was 0.15 × 10 ⁻³ wt.
%, Ethylene concentration 1.0 wt%, hydrogen to ethylene concentration ratio 0.15 × 10 ⁻³ (w / w), hexene-1 to ethylene concentration ratio at 0.62 (w / w), and total pressure 41 kg
/ Cm ² , and the average residence time is 0.80 hr, the first stage copolymerization is continuously performed in a liquid-filled state. Isobutane slurry containing ethylene / hexene-1 copolymer produced by copolymerization (polymer concentration: 23% by weight, polymer intrinsic viscosity: 3.2, hexene content: 0.54% by weight, copolymer density: 0.948 g / cm ³ ) as it is with an internal volume of 400 L
Was introduced into the second-stage polymerization reactor of No. 2 through a continuous tube having an inner diameter of 50 mm, and 55 L of isobutane was added without adding a catalyst.
hr, hydrogen, and further 4-methoxy-4-methyl-2-pentanone were supplied so that the molar ratio to titanium atoms in the catalyst in the second-stage polymerization reactor was 5, and the contents of the polymerization reactor were discharged at a required rate. However, at 90 ℃, ethylene 2
It was fed at a rate of 3.7 kg / hr and the ethylene concentration was 1.
20% by weight, hydrogen concentration ratio to ethylene is 15 × 10
^-3 (w / w), the total pressure is 41.0 kg / cm ² , and the residence time is 1.05 hr. The effluent from the second-stage polymerizer contained 3 parts of ethylene polymer mixture.
The polymer had an intrinsic viscosity of 1.6 and the density of the ethylene copolymer mixture was 0.9575 g / cm ³ . The production ratio of the first-stage and second-stage polymers is 47: 5.
3, the ethylene copolymer produced only in the second-stage polymerizer has an intrinsic viscosity of 0.18, a hexene-1 content of 0.03% by weight, and a density of 0.967 g / cm ³ . Equivalent to. The flexural modulus of this copolymer is 14500 kg.
f / cm ² and ESCR were 52 hr, and an ethylene-based copolymer having an excellent balance between rigidity and ESCR was obtained.

Example 4 Polymerization was carried out in the same manner as in Example 3 except that the compound added in the second stage was changed to methyl 4-methoxyacetoacetate. The results are shown in Table 1. Rigidity and ESCR
An ethylene-based copolymer having an excellent balance was obtained.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 3 except that the compounds corresponding to Examples 3 and 4 were not added in the second stage. The results are shown in Table 1. The ESCR was good, but the rigidity was low.

Comparative Example 3 This is an example in which butene-1 was used as a comonomer instead of hexene-1 using the same catalyst and the same polymerization reactor as in Example 1. 21.0 kg / hr of butene-1 and 0.25 kg / butene at 80 ° C. in the first-stage polymerization vessel.
hr, hydrogen concentration in liquid phase 0.21 × 10 ⁻³ wt%, ethylene concentration 1.0 wt%, butene-1 concentration ratio to ethylene 0.16 (w / w), average residence time Continuous polymerization was carried out under the condition of 0.9 hours. 2. Isobutane slurry containing ethylene / butene-1 copolymer produced by copolymerization (copolymer concentration 23% by weight, intrinsic viscosity of polymer 3.
2, the butene-1 content of the polymer is 0.69% by weight,
The density was 0.952 g / cm ³ . ) In the second-stage polymerization reactor, 55 L / hr of isobutane, hydrogen, and 4-methoxy-4-methyl-2-pentanone were fed so that the molar ratio to titanium atoms in the catalyst in the second-stage polymerization reactor was 5. Then, at 90 ° C., ethylene was fed at a rate of 23.7 kg / hr to keep the ethylene concentration at 1.20 wt%,
Second-stage polymerization is continuously carried out under the condition that the average residence time is 1.2 hours. The effluent from the second stage polymerizer contained 27% by weight of the ethylene copolymer mixture, and the intrinsic viscosity of the polymer was 1.
6, the density was 0.9592 g / cm ³ . The production ratio of the first-stage and second-stage polymers was 47:53, which is the same as in Example 1. The ethylene / butene-1 copolymer produced only in the second stage has an intrinsic viscosity of 0.18,
The butene-1 content is 0.03% by weight and the density is 0.9
This corresponds to 67 g / cm ³ . The flexural modulus of this copolymer was 14800 kgf / cm ² , and the ESCR was 45 hr. The molecular weights of the first-stage and second-stage polymers were the same as in Example 1, the densities of the first-stage and the second-stage were the same, and the production ratios of the first-stage and the second-stage were the same. Depending on whether -is butene-1 or hexene-1
It can be seen that there is a large difference in SCR and Example 1 is superior.

[0046]

[Table 1]

[0047]

EFFECTS OF THE INVENTION By carrying out the present invention, it is possible to produce an ethylene-based copolymer for blow molding, which has an excellent balance between rigidity and environmental stress crack resistance (ESCR).

Claims (7)

[Claims] 1. A Ziegler-type catalyst is used to produce ethylene and an α-olefin in a first polymerization zone to obtain a high molecular weight component,
When an ethylene-based copolymer is produced by a two-stage polymerization in which a low molecular weight component is polymerized in the second polymerization zone, the general formula: (In the formula, R ^{1 to} R ⁴ may be the same or different and each is a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a carbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group or a halogen. A compound represented by any of the atoms, wherein n represents an integer of 1 to 10) is added, the method for producing an ethylene-based copolymer. 2. The method for producing an ethylene-based copolymer according to claim 1, wherein a copolymer of ethylene and an α-olefin is subjected to two-stage polymerization by the following methods (a) and (b). . (A) Ethylene containing 0.2 to 5% by weight of an α-olefin having an intrinsic viscosity [η] _a ≧ 2 and having 5 or more carbon atoms and having 5 carbon atoms
Step a in which 30 to 70% of the above α-olefin copolymer is produced in the first polymerization zone, and intrinsic viscosity [η] _b =
B step for producing 70 to 30% of ethylene polymer of 0.1 to 1.0 in the second polymerization zone, and (b) the ratio [η] of [η] _a and [η] _b above. _a / [η]
_b is 4.5 to 20.0 and the intrinsic viscosity of the copolymer [η]
_c is 1.0 to 3.5. 3. The method for producing an ethylene copolymer according to claim 1, wherein the Ziegler type catalyst comprises a solid catalyst component containing at least magnesium, titanium and halogen and an organoaluminum compound. 4. The solid catalyst component according to claim 3,
(1) (a) Aluminum trihalide, (b) Si-
By contacting a co-milling product obtained by co-milling an organic compound having an O bond and (c) magnesium alcoholate with (2) a tetravalent titanium compound having at least one halogen atom in a liquid phase The method for producing an ethylene-based copolymer according to claim 3, which is the obtained solid catalyst component. 5. The solid catalyst component according to claim 3,
(1) (a) Aluminum trihalide, (b) Si-
A solid catalyst component obtained by bringing (2) a tetravalent titanium compound having at least one halogen atom into contact with an organic compound having an O bond and (c) a solid product of magnesium alcoholate. The method for producing the ethylene-based copolymer according to claim 3. 6. The compound added to the second polymerization zone has the general formula: (In the formula, R ⁵ and R ⁶ are the same or different and have 1 to 1 carbon atoms.
10 represents an alkyl group or an aryl group. 6. A compound represented by the formula (1) is added.
The method for producing an ethylene-based copolymer according to any one of 1. 7. The compound added to the second polymerization zone has the general formula: (In the formula, R ^{7 to} R ¹⁰ are the same or different and each is a hydrogen atom or an alkyl group or an aryl group having 1 to 10 carbon atoms, and m is an integer of 1 to 10.) The method for producing an ethylene-based copolymer according to any one of claims 1 to 5, wherein