JP2000128917A - Continuous production of ethylenic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for continuously producing an ethylenic polymer by which physical properties of the obtained polymer are presumed based on the polymerization condition, and the ethylenic polymer capable of rapidly corresponding to the fluctuation of the physical properties of the polymer, excellent in extrusion moldability and having a high melt tension is continuously produced. SOLUTION: This production method for homopolymerizing ethylene or copolymerizing the ethylene and other olefins continuously in the presence of solid catalytic components comprising a magnesium compound and a titanium compound, and a catalyst system containing an organoaluminum compound comprises controlling the concentration of the organoaluminum compound in the reaction system to control the polymerization activity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for continuously producing an ethylene polymer for controlling physical properties. More specifically, in producing an ethylene polymer having excellent extrusion moldability and high melt tension, which is suitable for hollow molding and inflation molding, etc., the physical properties of the obtained polymer are predicted by the polymerization conditions, and the physical properties in the polymerization process are estimated. The present invention relates to a method for continuously producing an ethylene-based polymer which can control the amount of ethylene.

[0002]

2. Description of the Related Art Ethylene polymers are widely and generally used as various molding materials, but required characteristics vary depending on the use and the molding method. For example, an ethylene polymer having a narrow molecular weight distribution and a relatively low molecular weight is suitable for a product manufactured by an injection molding method.

On the other hand, for products manufactured by inflation molding or blow molding, ethylene polymers having a wide molecular weight distribution and a relatively high molecular weight are suitable. Especially in hollow molding, for example, when molding large containers, to prevent drawdown of the parison or to secure uniform stretchability when molding products with complicated shapes, from the viewpoint of resin molding and physical properties It is necessary to select an ethylene polymer having high resin extrudability and high melt tension.

[0004] However, when the molecular weight distribution is widened and the extrudability and the melt tension are to be improved, the productivity in production is usually decreased in many cases. JP-A-2-308511 and the like have proposed a two-stage polymerization method in which a low molecular weight polymer is produced in one reactor and a high molecular weight polymer is produced in the other reactor. However, although the method according to the publication has a certain effect of the melt tension, it cannot be said that the effect of improving the melt tension or the like is sufficient in a region having high productivity in manufacturing. Further, the polymerization method disclosed in the publication has a disadvantage that fish eyes cannot be eliminated unless strong kneading conditions are selected.

[0005] For this reason, as a method not based on the two-stage polymerization method, Japanese Patent Application Laid-Open No. 5-230136 has been proposed in which a low molecular weight active site and a high molecular weight active site are contained in the same solid catalyst component. However, in the production of products in a continuous polymerization facility, the melt tension and SS (dependence of the melt viscosity on the shear stress) of the obtained product are measured, and the desired melt tension, When trying to obtain SS, measurement of the melt tension and SS takes a long time, so that there is a problem that the response is slow.

[0006]

SUMMARY OF THE INVENTION The present invention predicts the physical properties of a polymer to be obtained on the basis of polymerization conditions, responds quickly to fluctuations in the physical properties of the polymer, has excellent extrusion moldability, and has a high melt tension. And to provide a method for continuously producing an ethylene polymer having a high value.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve this problem. As a result, when the melt tension and SS were controlled by changing the concentration of organoaluminum, the physical properties and the polymerization activity were reduced. It has been found that a certain relationship exists, and that this relationship holds even when the amount of organoaluminum substantially fluctuates due to impurities or the like in the polymerization system.

That is, the present invention provides a method for continuously polymerizing ethylene or copolymerizing ethylene with another olefin in the presence of a catalyst system containing a solid catalyst component containing a magnesium compound and a titanium compound and an organoaluminum compound. An object of the present invention is to provide a method for producing an ethylene polymer, which comprises controlling the polymerization activity by controlling the concentration of an organoaluminum compound in a reaction system.

According to the present invention, the polymerization activity obtained as process data can be set to a predetermined value without waiting for the measurement results of the melt tension and SS which require time.
Since a polymer having a desired melt tension and SS value can be obtained, it is effective in terms of quick operation management.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, ethylene or ethylene and another olefin are polymerized using a solid catalyst component containing a magnesium compound and a titanium compound and a catalyst containing an organoaluminum compound. Examples of solid catalyst components include JP-A-5-230136 and JP-A-52-24292, and Japanese Patent Application Nos. 9-138707, 9-138708, and 9-1.
38710, 10-1016, 10-1010
17, 4-15806, 4-15807, 4
-15808, 59-5205, 59-5206 and the like can be used, and among them, JP-A-5-230136, Japanese Patent Application Nos. 9-138707, 9-1.
38708, 9-138710, 10-10101
6, the catalysts described in 10-101017 are preferred.

The method for producing these catalysts will be specifically described below. Production of Solid Catalyst Component The magnesium compound (a) used for producing the solid catalyst component (I) of the present invention has a general formula of Mg (OR ¹ ) _k X
A compound represented by _2-k (R ¹ : alkyl group, aryl group or cycloalkyl group, X: halogen, k = 0, 1 or 2) is used. Specifically, R ¹ has 15 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, tolyl, xylyl and cyclohexyl.
A compound to the extent that it is an alkyl, aryl, or cycloalkyl group, and X is chlorine, bromine, or iodine. Examples include diethoxymagnesium, ethoxymagnesium chloride, diphenoxymagnesium, magnesium chloride and the like. In the production of ordinary solid catalyst components, the particle size is controlled in the halogenation step described below so that the particle size can be arbitrarily controlled according to the applicable process. It is preferably in a homogeneous solution state. In such a case, dialkoxymagnesium, which is a compound in which k = 2, is preferable. On the other hand, the halogenation step can be performed in a non-uniform state by using a raw material magnesium compound having a controlled particle size. As the polyalkyl titanate compound (b), a compound represented by the following general formula is used.

[0012]

Embedded image

(Where R^TwoIs alkyl, aryl or
Represents a cycloalkyl group, which may be the same or different.
1 is an integer of 1 to 20. ) R in the above formula^TwoIs R¹The ones exemplified in
It is. Specifically, OR^TwoIs a butoxy group, and 1 is each
Compounds which are 2, 4, 7, 10 ^TwoBut professional
Compounds which are oxy groups and 1 is 2, 4, 7, 10 respectively
And the like. Among them, 1 is 4, 7, 10 respectively
Compounds are preferred. Furthermore, tetraalkoxy titanium (described later)
A small amount of H_TwoObtained by reacting O
Condensates of tetraalkoxy titanium can also be used
You. OR^TwoUses compounds in which a part of is substituted with halogen
I can do it.

Further, in order to adjust the halogenation rate and the liquid viscosity in the later-described halogenation step, a titanium compound (c) represented by the following general formula is usually used as necessary. (C) General formula Ti (OR ³ ) _m X _4-m (R ^{3 represents} an alkyl group, an aryl group or a cycloalkyl group and may be the same or different, X: halogen,
m = 1, 2, 3, or 4)

Examples of R ³ and X include those exemplified for R ¹ and X above. Specifically, tetraethoxytitanium, tetrapropoxytitanium, tetra-n-butoxytitanium and the like as the compound of m = 4, triethoxymonochlorotitanium, tripropoxymonochlorotitanium, tri-n-butoxymonochlorotitanium and the like as the compound of m = 3,
Examples of the compound with m = 2 include diethoxydichlorotitanium, dipropoxydichlorotitanium, di-n-butoxydichlorotitanium and the like, and compounds with m = 1 include ethoxytrichlorotitanium, propoxytrichlorotitanium, n-butoxytrichlorotitanium and the like. However, compounds in which m = 4 and 3 are preferred. Among them, tetra-n-butoxytitanium with m = 4, tri-n-butoxymonochlorotitanium with m = 3 and the like are preferable.

If necessary, an alcohol compound (d) represented by the following general formula is used for adjusting the affinity between the above-mentioned magnesium compound, polyalkyl titanate compound, titanium compound and a hydrocarbon solvent. (D) R ⁴ OH (where R ⁴ represents an alkyl, allyl or cycloalkyl group)

As R ⁴ , those exemplified for R ¹ can be similarly mentioned. Specific examples include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, n-pentyl alcohol, n-octyl alcohol and the like. The solid catalyst component used in the production of the ethylene polymer of the present invention is the magnesium compound,
Using a polyalkyl titanate compound, a titanium compound and an alcohol compound in some cases, a solution in a hydrocarbon solvent (in some cases, an insoluble portion may be left) is prepared. As the hydrocarbon solvent used for this, aliphatic hydrocarbons such as hexane, heptane and octane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene are used. In preparing a solution in a hydrocarbon solvent, the order of catalytic addition of a magnesium compound, a polyalkyl titanate compound, a titanium compound in some cases, and optionally an alcohol to be added can be appropriately selected without any particular limitation. To obtain the above-mentioned hydrocarbon solution, usually after adding and mixing the raw materials, 20 to 1
70 ° C., more preferably 70 ° C. to 150 ° C.
It is preferable to heat in the temperature range described above. If the temperature is lower than the above range, the solubility of the raw material may be extremely deteriorated, and the properties of the catalyst particles may be deteriorated. If the temperature is higher than the above range, the polyalkyl titanate compound (b) may be deteriorated, which is not preferable.

The amount of the solvent used is such that the total molar amount of the magnesium compound (a), the polyalkyl titanate compound (b) and the titanium compound (c) is the required amount so as to satisfy the following range with respect to the solvent used. . 0.01
(Mol / L) ≦ {total molar amount of (a), (b) and (c)} (mol) / solvent amount (L) ≦ 4 (mol / L)
Preferably 0.01 (mol / L) ≦ ｛(a) and (b)
Total molar amount of (c) and (c) / solvent amount (L)
≦ 2 (mol / L). If the concentration is below the above range, the yield of the catalyst per used amount of the solvent is extremely low, which is not practical.
On the other hand, if the concentration is higher than the above range, the viscosity of the hydrocarbon solution increases, which may hinder handling.

In some cases, one of a magnesium compound, an organic titanate compound and a titanium compound may be added after the heating treatment. To get the target performance,
The charge ratio of each raw material is usually in the following molar ratio range. 0 ≦ titanium compound (c) / magnesium compound (a) ≦
5 0.25 ≦ organic titanate compound (b) / magnesium compound (a) ≦ 4, preferably 0 ≦ titanium compound (c) / magnesium compound (a) ≦
2 0.25 ≦ organic titanate compound (b) / magnesium compound (a) ≦ 2 More preferably, 0.25 ≦ titanium compound (c) / magnesium compound (a) ≦ 1 0.25 ≦ organic titanate compound (b) / Magnesium compound (a) ≦ 1.5. Outside the above range, the polymerization activity may be reduced, the molecular weight distribution may not be broadened, the extrudability and melt tension may be insufficient, and the molding may not be suitable for large-sized hollow molding.

Then, the homogeneous hydrocarbon solution or suspension obtained as described above is treated with a halogenating agent to obtain a solid catalyst component. The halogenating agent is not particularly limited as long as it has the action, but is usually III.
, IV, V, halides of group VI elements, hydrogen halides, and the like. Specifically, titanium tetrachloride, silicon tetrachloride,
Examples include chlorides such as tin tetrachloride and vanadium tetrachloride, and chlorine-containing compounds such as hydrogen chloride. Of these, a single product or a mixture of two or more thereof may be used. Among them, titanium tetrachloride, silicon tetrachloride and the like are preferable.

The method of treating with these halogenating agents is not particularly limited, but the treatment is usually performed at a temperature in the range of 20 to 200 ° C, preferably 80 to 130 ° C. If the treatment is carried out at a temperature below the above, halogenation may be extremely insufficient, which is not preferable. If the treatment is carried out at a temperature higher than the above, the polyalkyl titanate (b) may deteriorate, which is not preferable. The halogenation treatment may be performed once or may be repeated twice or more. The solid catalyst component generated as described above separates and cleans a solid with a hydrocarbon solvent, and finally obtains a solid catalyst component to be subjected to prepolymerization.

In the present invention, a small amount of an electron donating compound may be allowed to coexist at any stage before the solid catalyst component is formed, or after the solid catalyst component is formed, a small amount of the electron donating compound may be added. It may be treated with a compound. Such electron donating compounds generally include phosphorus-containing compounds, oxygen-containing compounds, sulfur-containing compounds, nitrogen-containing compounds, and the like. Of these, an oxygen-containing compound is preferably used. As the oxygen-containing compound, for example, the following formula

R ⁵ OR ⁶ , R ⁵ COR ⁶ , R ⁵ (COOR ⁶ ) _p (wherein, R ⁵ and R ⁶ each represent a hydrocarbon group which may be substituted with an alkoxy group, and are bonded to each other to form a ring; And p is an integer of 1 to 3), and among them, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate and the like are preferable. Aromatic carboxylic esters or metal salts of aromatic carboxylic acids, such as ethyl phenylacetate, methyl benzoate, ethyl benzoate, methyl toluate, methyl anisate, ethyl anisate, methyl ethoxybenzoate, and ethyl cinnamate Carboxylic acid ester, benzoic acid-
and silicon-containing carboxylic esters such as β-trimethoxysilylethyl. The amount of the electron donating compound is not particularly limited, but is usually selected to be 10 mol or less, preferably 0.01 to 1 mol, per 1 mol of the magnesium compound.

The solid catalyst component prepared through the prepolymerization above steps is subjected to prepolymerization. The prepolymerization is usually carried out by bringing the solid catalyst component into contact with an organoaluminum compound in a hydrocarbon solvent and, if necessary, supplying an α-olefin having 2 to 20 carbon atoms in the presence of hydrogen.

Specifically, butane as a hydrocarbon solvent,
Aliphatic hydrocarbons such as pentane, isopentane, hexane, heptane, and octane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene, toluene, and xylene are used. The used solid catalyst component is supplied so as to have a concentration of 5 to 80 (g-solid catalyst component / L-hydrocarbon solvent) per the hydrocarbon solvent. If the concentration of the solid catalyst component is lower than the above range, the productivity is lowered and is not practical. On the other hand, if the solid catalyst component concentration is higher than the above range, handling such as transfer of the prepolymerized catalyst may be impaired, which is not preferable.

The organoaluminum compound is represented by the general formula: AlR ⁷ qR ⁸ rXs (wherein R ⁷ and R ⁸ are alkyl, allyl or cycloalkyl groups, and when R ⁷ and R ⁸ are present, they are the same or different. X represents a halogen atom.
Further, 0 ≦ s <3 and q + r + a = 3 are satisfied. ) Are used. R ⁷ and R ⁸ are the same as those exemplified for R ¹ . X is chlorine, bromine, iodine or the like. Specifically, trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum monochloride, dimethylaluminum monochloride, ethylaluminum sesquichloride, methylaluminum sesquichloride, ethylaluminum dichloride, methylaluminum dichloride And the like. Among them, diethyl aluminum monochloride which is a halogen-containing organic aluminum, dimethyl aluminum monochloride, ethyl aluminum sesquichloride, methyl aluminum sesquichloride, ethyl aluminum dichloride,
Methyl aluminum dichloride and the like are preferred.

In particular, when a halogen-containing organoaluminum compound is used, its use amount is 0.1 to 5 (mmol
/ G-solid catalyst component), preferably 0.5-4.
(Mmol / g-solid catalyst component).
When these halogen-containing organoaluminum compounds are used, a polymer having a wide molecular weight distribution and a high melt tension can be obtained. When the amount is too small, the activation of the solid catalyst component becomes insufficient. When the amount is too large, the melt tension of the polymer tends to decrease.

The prepolymerization temperature is usually in the range of 0 to 110 ° C., preferably 10 to 90 ° C. When the pre-polymerization temperature is lower than the above range, the pre-activation of the solid catalyst component is insufficient, and sufficient activity may not be exhibited during the main polymerization, which is not preferable. On the other hand, when the prepolymerization temperature is higher than the above range, the prepolymerized polymer dissolves and solid catalyst particles cannot be obtained in a slurry form, which is not practical for handling.

The prepolymerization time is usually in the range of 1 to 600 minutes,
More preferably, it is carried out in the range of 10 to 300 minutes. When the prepolymerization time is shorter than the above range, the contact time with the organoaluminum compound is short, and the activation of the solid catalyst component becomes insufficient. If the prepolymerization time is longer than the above range, the solid catalyst component may be overreduced, which is not practical. The α-olefin feed is performed within the above prepolymerization time. The supply method may be from the gas phase part or the liquid phase part of the hydrocarbon solvent. The α-olefin used has 2 carbon atoms.
~ 20, specifically ethylene, propylene, butene-1, pentene-1, hexene-1, octene-1,
4-methylpentene-1, 3-methylbutene-1, styrene, etc., which may be used alone or in combination. Among them, ethylene, propylene, styrene and the like are preferred.

The α-olefin may be supplied continuously or intermittently at time intervals. In order to adjust the molecular weight of the prepolymerized polymer, if necessary, the reaction is carried out in a hydrocarbon solvent in the presence of hydrogen. The prepolymerization yield of the solid catalyst component is 0.05 to 100 (g-polymer / g-solid catalyst component). If the prepolymerization yield is less than the above range, the protection effect of the solid catalyst component by the prepolymerized polymer becomes insufficient, and the solid catalyst component may be crushed during the main polymerization and fine powder may be generated, which may cause a problem in the process. When the pre-polymerization yield is above the above range, the amount of solid catalyst component in the pre-polymerized solid catalyst component is reduced. Is not realistic.

In this prepolymerization, an antistatic agent can be supplied as needed to prevent the solid catalyst component from being charged. The prepolymerized solid catalyst component contains an unreacted organoaluminum compound in the hydrocarbon solvent of the cleaning solution, and is usually washed with a hydrocarbon solvent. The washing solvent is
The solvents listed in the pre-polymerization solvent are used, but the same solvent or a different solvent may be used. Further, the pre-polymerized solid catalyst component after washing can be used either in a slurry state in a solvent or in a dry state after removing the solvent and drying. In the present invention, it is desirable to use a catalyst that has been subjected to the above prepolymerization.

The solid catalyst component obtained as described above is used for homopolymerization of ethylene or copolymerization with an α-olefin in the presence of an organic aluminum compound. As the polymerization form, a slurry polymerization method or a solution polymerization method is usually used. Less than,
This will be specifically described. The organoaluminum compounds used include the following.

Typical examples are trialkylaluminums such as triethylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, trioctylaluminum, dialkylaluminum hydrides such as diethylaluminum hydride and diisobutylaluminum, and dialkyls such as diethylaluminum chloride. Aluminum halogenide and the like can be mentioned. Of these organic aluminums, trialkyl aluminums are preferable, and triethyl aluminum, triisobutyl aluminum and the like are preferable.

Further, two or more kinds of organoaluminum compounds may be used in combination. The present invention uses a single catalyst component to control a polymer having a desired molecular weight distribution by an easy method, and as a result of intensive studies on a method capable of producing, the melt tension, SS, and polymerization activity are represented by the following formulas. This was done by finding that it is controlled by an index (hereinafter referred to as an Al product).

Here, SS is a value indicating the dependency of the melt viscosity on the shearing stress, and is represented by a flow ratio under a load of 21.6 kg and a load of 5 kg according to ASTM-D-1238-57T. Al product = (Feed amount of organoaluminum) ² / Feed amount of solvent / Feed amount of solid catalyst

According to the present invention, it is possible to control the melt tension, SS and polymerization activity of the formed polymer to predetermined values even in a situation where both the catalyst concentration and the organic aluminum concentration change. This is suitable as a control index. In the case of slurry polymerization or the like using a hydrocarbon solvent, the Al product is usually 0.01 to 100 (mmol ² /
Range of L- solvent / g- solid catalyst component weight), preferably in the range of 0.05 to 50 (mmol ² / L- solvent / g- solid catalyst component amount). If the Al product is too small, the polymerization activity may be significantly reduced.

When the Al product is larger than the above value,
The molecular weight distribution of the obtained polymer may be narrow and the melt tension may be reduced. When large-sized hollow molding is carried out, there may be a problem that molding workability such as uniform stretchability is inferior. α
The olefin is usually of 2 to 20 carbon atoms, propylene, butene-1, pentene-1, hexene-1, octene-1, 4-methylpentene-1, 3-methylbutene-1,
Styrene and the like can be mentioned. Dienes can also be used.

As described above, the polymerization reaction can be carried out by solution polymerization in addition to slurry polymerization performed in an inert hydrocarbon solvent. At this time, aliphatic hydrocarbons such as butane, pentane, isopentane, hexane, heptane and octane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene are used as the hydrocarbon solvent. .

The polymerization reaction is usually selected from a temperature range of 20 to 200 ° C. and a pressure range of 1 to 100 (kgf / cm ² ). In the present invention, a polymer having a desired molecular weight can be obtained by allowing hydrogen to be present in the polymerization reaction zone. Further, in the main polymerization, not only a single-stage polymerization method but also a multi-stage polymerization method can be employed. According to the present invention, the melt tension and SS can be arbitrarily controlled by adjusting the polymerization activity by adjusting the Al product. The polymerization activity can be freely selected between 200 and 1000. When continuously polymerizing or copolymerizing ethylene alone or ethylene and an α-olefin using a catalyst system in which a specific catalyst component and an organoaluminum compound are combined, a correlation between a previously prepared polymerization activity and a melt tension. The polymerization activity is adjusted so that the desired melt tension is obtained from the relationship, or the desired SS is obtained from the correlation between the polymerization activity and SS prepared in advance.
The polymerization activity is adjusted so that the polymerization activity is obtained.

[0040]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Various physical properties and the like in the examples were determined by the following methods.

(1) Catalyst polymerization activity KK = (polymer produced (g)) / (catalyst amount (g)) / (polymerization time (hr)) / (olefin partial pressure (kgf / c)
m ² ))

(2) Melt index (HLMI) HLMI is based on ASTM-D-1238-57T,
It was measured at 190 ° C. under a load of 21.6 kg.

(3) Outflow ratio (SS) SS as a measure of the molecular weight distribution is a value indicating the shear stress dependence of the melt viscosity, and is based on ASTM-D-1238-57T under a 21.6 kg load and a 5 kg load. Expressed as the outflow ratio. The larger the SS, the better (usually 23 or more). If the SS is insufficient, the molecular weight distribution is narrow and the extrudability during resin extrusion for large-sized hollow molding deteriorates.

(4) Melt Tension The melt tension (hereinafter, referred to as MT) was measured using a 30 mmφ single screw extruder, and a pelletized sample with a full flight screw was used under the following conditions using a melt tension tester manufactured by Toyo Seiki Co., Ltd. Was measured.

The measurement conditions were 1 mmφ, 5 mmL, inflow angle 6
190 ° C. using a 0 ° nozzle at an extrusion rate of 0.44 g /
It was measured under the conditions of min and a take-up speed of 0.94 m / min, and expressed in units (g). Further, the melt index (referred to as HLMI) of the above 21.6 kg load is 5.5 (g / 1).
(0 min), but in order to convert to MT at this time (hereinafter referred to as M value), a conversion formula of M value = MT + 10 × Log (HLMI / 5.5) was used. Usually, the M value is preferably 12 g or more. If this is insufficient, the parison draws down during hollow molding, especially when molding a large container, or when a product having a complicated shape is molded, uniform stretchability deteriorates. In addition, if the physical properties of the product are insufficient, fire resistance deteriorates.

(5) Fish Eye Determination Fish eye was determined using a 30 mmφ single screw extruder.
The sample pelletized by the full flight screw was formed into a sheet by a pressure press, and the sheet was heated and vacuum formed into a hat shape to determine the presence or absence of fish eyes. Relationship between polymerization activity by continuous polymerization, melt tension and SS value

REFERENCE EXAMPLE 1 After supplying 300 L of normal hexane to a polymerization vessel having an internal volume of 500 L, the temperature was maintained at 90 ° C., hydrogen was supplied until the pressure became 7 kg / cm ² , and normal hexane was continuously supplied at 70 L / Hr. While the triisobutylaluminum was supplied at 8.5 mmol / Hr, the prepolymerized solid catalyst component was supplied at 5.2 g / Hr. The supply amount of ethylene was adjusted so that the hydrogen / ethylene partial pressure ratio in the gas phase became 1.45, and the residence time of the slurry when the total pressure was constant was 4 hours. The HLMI of a sample obtained by pelletizing the polymer discharged from the reactor 12 hours after the start of ethylene supply with a full flight screw using a 30 mmφ single screw extruder was 6.4 g / 10 min, SS was 33.0,
MT was 13.0 g (M value: 13.7 g). Also,
The polymerization activity of the catalyst was 365. Table 1 shows the results.

Reference Examples 2 and 3 Polymerization was carried out in the same manner as in Reference Example 1, except that the hydrogen partial pressure, the ethylene partial pressure, and the supply amount of triisobutylaluminum were changed as shown in Table 1. . Table 1 shows the results.

<Reference Examples 4 and 5> In Reference Example 1, the charged amount of the prepolymerized solid catalyst component, hydrogen partial pressure, ethylene partial pressure,
Polymerization was carried out in the same manner as in Reference Example 1, except that the supply amount of triisobutylaluminum was changed as shown in Table 1. Table 1 shows the results.

<Reference Examples 6 and 7> In Reference Examples 2 and 3,
The antistatic agent Stadis425 was supplied at 1.38 g / Hr, and the amount of triisobutylaluminum supplied was as shown in Table 1.
Polymerization was carried out in the same manner as in Reference Example 1, except for the following changes.

The correlation between the polymerization activity and the melt tension in Reference Examples 1 to 7 is shown in FIG. FIG. 2 shows the correlation between the polymerization activity and the SS. Sta
When dis425 was added, the Al content and polymerization activity,
It can be seen that the relationship between SS and MT changes, but the relationship between polymerization activity and SS and MT is constant.

Example 1 Using the continuous polymerization reactor used in Reference Example 1, and using exactly the same conditions as in Reference Example 7, polymerization activity 810, HLMI 8.2, MT 10.6, M value 1
2.4, SS23 polymer was obtained. Here, in order to obtain a polymer having an M value of 13 and an MLMI of 6.0, the TIBAL feed amount was set to 11.4 mol / Hr and the ethylene feed amount was kept constant in order to obtain a polymerization activity of 580. Activity gradually decreased, and ethylene partial pressure increased.

After 8 hours, the polymerization activity is 630 and the ethylene content is
Pressure is 4.2kg / cm^TwoAnd H _TwoPartial pressure is 6.3kg
/ Cm^TwoAnd Here, further, the TIBAL feed amount
When it was set to 11.0 mol / Hr, the activity was further increased after 8 hours.
570, ethylene partial pressure 4.5 kg / cm^TwoIt became. This
At the point of time, when the physical properties of the obtained polymer were measured,
MLMI = 6.5 g / 10 min, MT 12.4, M value 1
3.1, which satisfied the predetermined value. The polymerization activity is 630
The time of the change was nighttime, and there was no physical property evaluation system.
About 12 hours more than the next morning
Was able to be performed quickly.

[0054]

[Table 1]

[0055]

[Brief description of the drawings]

FIG. 1 is a graph showing a correlation between polymerization activity and melt tension in Examples.

FIG. 2 is a graph showing the correlation between polymerization activity and SS in Examples.

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Claims (6)

[Claims] An ethylene-based polymer which continuously homopolymerizes ethylene or copolymerizes ethylene and another olefin in the presence of a catalyst system containing a solid catalyst component containing a magnesium compound and a titanium compound and an organoaluminum compound. A method for continuous production of an ethylene-based polymer, wherein the polymerization activity is controlled by controlling the concentration of an organoaluminum compound in a reaction system. 2. The method for continuously producing an ethylene-based polymer according to claim 1, wherein the concentration of the organoaluminum is controlled so that the Al product represented by the following equation falls within a predetermined range. Al product = (Feed amount of organoaluminum) ² / Feed amount of solvent / Feed amount of solid catalyst 3. The continuous production method for an ethylene-based polymer according to claim 1, wherein the solid catalyst component contains a titanium compound containing a Ti—O—Ti bond. 4. The continuous production of an ethylene-based polymer according to claim 1, wherein the solid catalyst component contains a titanium compound containing a Ti—O—Ti bond and a titanium compound containing no Ti—O—Ti bond. Method. 5. The solid catalyst component according to claim 1, wherein said solid catalyst component contains chlorine.
5. The method for continuously producing an ethylene-based polymer according to any one of items 1 to 4. 6. A solid catalyst comprising: (a) a magnesium compound represented by the general formula Mg (OR ¹ ) _k X _{2 -k} (R ¹ : alkyl group, aryl group or cycloalkyl group, X: halogen, k = 0, 1 or 2) (R ² represents an alkyl group, an aryl group or a cycloalkyl group and may be the same or different and 1 = 2 to 20) as an essential component. (C) General formula Ti (OR ³ ) _If necessary, in the presence or absence of a titanium compound represented by _m X _4-m (R ³ : alkyl group, aryl group or cycloalkyl group, X: halogen, m = 1, 2, 3, or 4) Using a halogenating agent, a hydrocarbon solvent solution containing an alcohol compound represented by the general formula (d) R ⁴ OH (R ⁴ : an alkyl group, an aryl group or a cycloalkyl group) and leaving a uniform or partially heterogeneous portion is prepared. The method for continuously producing an ethylene-based polymer according to any one of claims 1 to 5, wherein a solid catalyst component obtained by the treatment is used.