JPH0768309B2 - Method for producing ethylene copolymer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an ethylene copolymer composition such as polyethylene for hollow molding. More specifically, it has excellent mechanical strength, moldability and the like. The present invention also relates to a method for producing an ethylene copolymer composition capable of continuously producing the ethylene copolymer composition with high productivity over a long period of time.

[Prior Art and Its Problems] As a method for producing polyethylene for blow molding having a wide molecular weight distribution, a method using two-step polymerization has been known. Polyethylene produced by this two-step polymerization method has an excellent balance between rigidity and environmental stress crack resistance (ESCR) compared to polyethylene obtained by the one-step polymerization method,
(1) Since the fusion strength of the pinch-off portion of the hollow molded product is small, the allowable range of the pinch-off shape of the mold is narrow, the defect occurrence rate of the product is high, and (2) the die swell is small.

As a method for improving the drawbacks of such a two-step polymerization method, a three-step polymerization method is proposed in Japanese Examined Patent Publication No. 59-10724. However, the polyethylene produced by this three-stage polymerization method was improved in die swell but was insufficient in improving the pinch-off fusion bondability. Further, in the three-stage polymerization method, since three polymerization tanks are used, the control of polymerization becomes complicated and the equipment cost becomes high.

The present inventors have solved the above-mentioned problems, and are excellent in hollow moldability, particularly pinch-off fusion bondability, die swell, high-speed moldability, appearance, and the like, and have high mechanical properties and ESCR, and a good balance thereof. The inventors have conducted extensive studies to develop a method for producing an ethylene copolymer composition with high productivity.

[Means for Solving the Problems] The present invention for solving the above problems includes tetravalent titanium and 4
Using a solid catalyst component containing valency zirconium, magnesium and halogen and a catalyst containing an organoaluminum compound as a main component, and (a) step: at a temperature of 30 to 80 ° C., other α-olefin contents are 10% by weight or less, intrinsic viscosity [η] is 10 to 40 dl / g
Of ethylene homopolymer or copolymer of 1 to 23% by weight based on the total amount of polymerization (b) step: at a temperature of 60 to 100 ° C, the content of other α-olefins is 15 Weight% or less, intrinsic viscosity [η] is 1.0 to 5.0
The process of producing an ethylene homopolymer or copolymer of dl / g at a ratio of 77 to 99% by weight of the total polymerization amount is carried out in any order. The intrinsic viscosity [η] is 3.0. It is a method for producing an ethylene copolymer composition having a density of ˜5.0 dl / g and a density of 0.940 to 0.961 g / cm ³ .

Catalyst The catalyst used in this polymerization reaction is Ti (IV) and Zr.
A binary transition metal catalyst containing (IV) is used. Specifically, Ziegler type catalysts such as those described in JP-A-57-12006, JP-A-57-12007, Japanese Patent Application No. 62-137712 and the like can be used.

That is, as such a catalyst, for example, (A) a solid content produced by reacting a compound containing at least titanium, magnesium and halogen with tetraalkoxyzirconium and / or zirconium tetrahalide contains an alkoxy group. A solid product obtained by reacting a halogen-containing titanium compound and (B) an organoaluminum compound as an active ingredient; (A) reacting a compound containing at least titanium, magnesium and halogen with tetraalkoxyzirconium A solid product obtained by reacting the produced solid content with an organic aluminum halide and (B) an organoaluminum compound as an active ingredient, (A) a mixture of magnesium dialkoxide and titanium tetraalkoxide with isopropa Alcohol and other alkanols to form a magnesium-containing solid complex, which is then reacted with zirconium tetraalkoxide or zirconium tetrahalide or both, and the reaction product obtained is further added with an organic aluminum halide. Examples of the catalyst include a solid catalyst component prepared by the reaction and (B) an organoaluminum compound component.

Among these, those having a Zr to Ti molar ratio of 0.5 to 20 are particularly preferable.

Examples of the compound containing at least titanium, magnesium and halogen include magnesium oxide,
Solid substances obtained by reacting titanium inorganic halide with magnesium inorganic compounds such as magnesium hydroxide, magnesium carbonate, magnesium sulfate and magnesium halide, or various magnesium compounds are sequentially reacted with silicon halide, alcohol and titanium halide. Obtained by solid substance, or dialkoxy magnesium such as magnesium diethoxide and magnesium sulfate,
Mention may be made of solid substances obtained by reacting with titanium halide.

Further, as the compound containing at least titanium, magnesium and halogen, magnesium oxide, magnesium hydroxide, a precipitate formed by sequentially reacting magnesium sulfate, silicon halide and alcohol to an Mg-O bond-containing inorganic compound such as magnesium carbonate. Silicon halides or organosilicon compounds (eg SiCl ₄ , CH ₃ OSiC)
l ₃ , (CH ₃ O) _2- SiCl ₂ , (CH ₃ O) ₃ SiCl, Si (OCH ₃ ) ₄ , C ₂ H ₅ OSi
Cl ₃ , (C ₂ H ₅ O) ₂ SiCl ₂ , (C ₂ H ₅ O) ₃ SiCl, Si (OC ₂ H ₅ ) ₄ etc.)
Also, it is possible to use a solid substance obtained by reacting titanium halide, or else a dialkoxy magnesium is reacted with an alcohol adduct of magnesium halide such as MgCl ₂ .6C ₂ H ₅ OH and then treated with alcohol. It is also possible to use a solid substance obtained by reacting the obtained product with titanium halide.

Examples of the halogen-containing titanium compound which may contain an alkoxy group include TiCl ₄ , TiBr ₄ , Ti (OCH ₃ ) Cl ₃ , T
Examples thereof include i (OC ₂ H ₅ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₃ Cl, and the like, or a mixture thereof.

Examples of the organic aluminum compound include trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, diethyl aluminum monochloride, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride, dioctyl aluminum monochloride, ethyl aluminum dichloride, diethyl aluminum monoethoxy. Examples thereof include isopropyl aluminum dichloride, ethyl aluminum sesquichloride, and the like.

As the organic aluminum halide, for example, dimethyl aluminum monochloride, diethyl aluminum monochloride, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride, methyl aluminum dichloride, ethyl aluminum dichloride, isopropyl aluminum dichloride, isobutyl aluminum monochloride, or the like. A mixture may be mentioned.

The titanium tetraalkoxide or zirconium alkoxide can be represented by the general formula M (OR) ₄ (1) (wherein R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group and an aralkyl group, and M is Titanium or zirconium) and such compounds include, for example, tetramethoxytitanium, tetraethoxytitanium, tetra (n-propoxy) titanium, tetra (n-butoxy) titanium, tetra (n-pentoxy). ) Titanium, tetra (n-
Hexoxy) titanium, tetra (n-heptoxy) titanium, tetra (n-octoxy) titanium, tetracyclopentoxy titanium, tetracyclohexoxy titanium, tetracycloheptoxy titanium, tetracyclooctoxy titanium, tetraphenoxy titanium and titanium thereof. The zirconium compound corresponding to a compound can be mentioned.

Step (a) In step (a), the polymerization temperature is selected to be 30 to 80 ° C. Here, the reason for selecting the polymerization temperature from 30 to 80 ° C is that the polymerization temperature is
This is because if it is less than 30 ° C, the productivity is low, and if the polymerization temperature exceeds 80 ° C, it becomes difficult to control the intrinsic viscosity [η].

In step (a), the content of other α-olefin is 10% by weight or less, preferably 5% by weight, and the intrinsic viscosity [η] is 10 to 40 dl /
g, preferably 15 to 30 dl / g of ethylene homopolymer or copolymer [component (A)] in an amount of 1 to 23% by weight, preferably 3 to 20% by weight, based on the total polymerization amount. Is copolymerized with α-olefin.

Here, the reason for limiting the content of other α-olefins, the intrinsic viscosity [η] and the total amount of polymerization is that the component (A) exceeds 10% by weight and the rigidity of the composition decreases. Because. Also, the intrinsic viscosity [η] is 10 dl / g
If less than, the pinch-off fusion property and fluidity of the composition deteriorate,
This is because if it exceeds 40 dl / g, the impact resistance will decrease and many fish eyes will be generated in the product. If the content of the other α-olefin exceeds 10% by weight, it may be difficult to continuously operate for a long period of time.

There are various α-olefins other than ethylene, for example, α-olefins having 3 to 10 carbon atoms, preferably 3 to 8 carbon atoms, specifically propylene and butene-1,
Examples include hexene-1 and octene-1.

In the step (a), the component (A) is produced in a proportion of 1 to 23% by weight based on the total amount of polymerization. Component (A) is 1 to 23% by weight of the total polymerization amount.
The reason why the composition is produced at the ratio of (A) is less than 1% by weight in the whole composition, the composition pinch-off fusion property and compatibility are deteriorated. Is worse.

Step (b) In the step (b), the polymerization temperature is selected to be 60 to 100 ° C. The reason for choosing the polymerization temperature from 60 to 100 ° C is that the polymerization temperature is 60 ° C.
If it is less than 100 ° C, productivity is low, and if the polymerization temperature exceeds 100 ° C, a part of the polymer is in an agglomerated state, which makes continuous operation difficult.

In the step (b), the content of the other α-olefin is 15% by weight or less, preferably 3% by weight or less, and the intrinsic viscosity [η] is 1.0 to 5.0.
Polymerization of ethylene or copolymerization of ethylene with another α-olefin is carried out so that an ethylene homopolymer or copolymer [component (B)] having a dl / g, preferably 1.5 to 4.0 dl / g is produced. .

Other α-olefin content and intrinsic viscosity [η] in the ethylene homopolymer or copolymer obtained here
The reason for limiting the above is that if the content of other α-olefin exceeds 15% by weight, the solvent-soluble component increases, and the rigidity and ESCR balance of the resulting composition deteriorate. Further, when the intrinsic viscosity [η] is less than 1.0 dl / g, the solvent-soluble component increases, and when it exceeds 5.0 dl / g, the fluidity of the composition decreases.

Here, as the α-olefin other than ethylene, the same α-olefin as described in the step (a) can be exemplified. The α-olefin used in step (b) may be of a different type or the same type as the α-olefin used in step (a). The same type is preferable.

In the step (b), the component (B) is produced in a proportion of 77 to 99% by weight based on the total polymerization amount.

The polymerization method in each step of the method of the present invention may be suspension polymerization, solution polymerization, gas phase polymerization, or the like, and may be continuous or batch. For example, when suspension two-stage polymerization is carried out, an inert solvent such as pentane, n-hexane, cyclohexane, heptane, benzene or toluene can be used as a solution.

In the present invention, either of the steps (a) and (b) may be performed first, and it is optional.

Ethylene copolymer composition The intrinsic viscosity [η] of the whole ethylene copolymer composition produced by the present invention is 3.0 to 5.0 dl / g, preferably 3.2 to 4.5.
dl / g. Here, the intrinsic viscosity [η] of the entire composition is 3.
When it is less than 0 dl / g, the ESCR is lowered, the blow moldability is deteriorated, and many fish eyes are generated. On the contrary, 5.0dl / g
If it exceeds the range, the high speed hollow moldability is deteriorated.

The density of the ethylene copolymer composition produced by the present invention is 0.940 to 0.961 g / cm ³ , preferably 0.943 to 0.958 g / cm ^3.
And the preferred MI is 0.01-0.08 g / 10 min. If the density of the ethylene copolymer composition is less than 0.940 g / cm ³ , the rigidity is low, and if it exceeds 0.961 g / cm ³ , the ESCR decreases.

According to the method of the present invention, the ethylene copolymer composition as described above can be efficiently and continuously produced. Furthermore, according to the method of the present invention, it is possible to efficiently produce polyethylene for applications where high rigidity and high ESCR are not required.

The ethylene copolymer composition produced according to the present invention,
It has excellent blown moldability, pinch-off fusion bondability, and large die swell. It has excellent appearance and high fluidity, and therefore has excellent high-speed moldability. In addition, the melt tension is large, and breakage of the parison can be prevented. Furthermore, this composition or a molded product obtained from it has a high ESCR and a high rigidity, and its balance is excellent, and its impact resistance is excellent.
Therefore, the composition obtained by the method of the present invention can be effectively used as a resin material for not only blow molding but also inflation molding, and further as a material for clothing of steel pipes.

EXAMPLES Next, the present invention will be described in more detail by way of examples.

(1) Each physical property was measured as follows.

Intrinsic viscosity Measured in decalin at 135 ° C.

Density Measured according to JIS-K 7112.

ESCR ASTM D-1693 compliant, temperature 50 ° C, surfactant [Nissan Nonion 10% aqueous solution, F ₅₀ value] Tensile modulus JIS-K 6760 compliant, measurement temperature 23 ° C Melt tension Melt tension tester manufactured by Toyo Seiki Co., Ltd. Use, Orifice D = 2.10m / m, L = 8.00 ° / m, temperature 190 ℃, Plunger descending speed 15mm / min, Thread take-up speed 10rpm Measured value Izod impact strength Compliant with ASTM D-256 , Notched, temperature 23 ℃ Moldability 10 as 90mmφ die manufactured by Ishikawajima Harima Heavy Industries Co., Ltd.
l Set the set temperature to C1, C using an accumulator type machine.
2, C3, adapter, CH1, CH2, and die in this order at 180, 190, 200, 220, 220, 220, and 220 ° C., respectively, to obtain a container as a 5 kg-weight molded product in a molding cycle of 5 minutes.

(2) The wall thickness of the obtained container was measured as follows.

Thickness of pinch-off The center of the pinch-off portion at the bottom of the container was cut out at a right angle to the pinch-off portion, and the minimum thickness of the pinch-off portion was measured with a caliper.

Thickness of convex portion The vicinity of the convex portion of the mold on the top of the container was cut out in a direction perpendicular to the pinch-off portion, and the minimum wall thickness was measured with a caliper.

(Example 1) (1) Production of Mg-containing solid composite body 1 (kg) (3.8mol) of Mg (OEt) ₂ and Ti (O) in 10 l of n-heptane.
-n-Bu) ₄ 1.9 kg (5.6 mol) is added and heated at 100 ° C for 3 hours to form a uniform solution. The whole amount of this homogeneous solution was added dropwise to 12 l of isopropanol with stirring at 20 ° C for 1 hour, and stirring was continued for another hour. The solid formed was washed with dry hexane until no Ti was detected in the washing liquid. The specific surface area of the obtained solid composite is 130 m ² /
The g and titanium contents were 0.62% by weight.

(2) Manufacture of solid catalyst component Zr (On-Bu) ₄ 450g (1.2mol) and Ti (On-Bu) ₄ 200g (0.
At a temperature of 20 ° C., 5 l of hexane in which 6 mol) was dissolved was stirred into the Mg-containing solid composite slurry obtained in (1) above.
The mixture was added dropwise over 15 minutes and further reacted for 90 minutes under reflux.
While stirring 10.2 l of a 50 wt% hexane diluted solution of EtAlCl _2, the mixture was added dropwise at 20 ° C. for 30 minutes, and further reacted under reflux for 60 minutes. It was washed with dry hexane until no chlorine was detected in the liquid, and the total volume was adjusted to 50 l with hexane. The contents of Ti and Zr in the solid catalyst component were 1.76 wt% -Ti and 6.10 wt% -Zr in terms of metal simple substance.

(3) Ethylene Copolymer In order to obtain a polymer having the intrinsic viscosity shown in the table, ethylene 9 kg / hr, hexane 26 l / hr, butene-172 g / hr and hydrogen in the first stage polymerization reactor of 200 l volume. While continuously feeding, the catalyst was introduced at a rate of 0.6 mmol / hr in terms of Ti and 18 mmol / hour of triisobutylaluminum, and polymerized at 80 ° C. under a condition of a residence time of 3 hours. Guide the contents of the polymerization vessel to the hydrogen degassing tank continuously at a predetermined speed,
After the hydrogen was separated, it was introduced into a 200 l second-stage polymerization reactor.
In the second stage polymerization reactor, ethylene 1kg / hr, hexane
Continuously feeding 3 l / hour, at a polymerization temperature such that a polymer having an intrinsic viscosity shown in Table 1 is obtained, a residence time of 2.5
Polymerization was carried out under the condition of time.

After completion of the reaction, the obtained ethylene copolymer was subjected to various physical property tests. Table 2 shows the measurement of these physical properties.

(Examples 2 to 6) The same procedure as in Example 1 was carried out except that the polymerization conditions in the first step and the second step were changed as shown in Table 1.

(Example 7) Ethylene 1 kg / hr, hexane 15 l / hr, butene-1 20 g / hr were continuously fed to a 200 l first-stage polymerization reactor, and the catalyst used in Example 1 was converted into Ti. 0.6 mmol /
It was introduced at a rate of 18 mmol / hour of triisobutylaluminum and polymerization was carried out at a polymerization temperature such that a polymer having an intrinsic viscosity shown in the table was obtained and a residence time of 4 hours. Continuously transfer the contents of the polymerization vessel at a predetermined speed.
It was led to a 0-liter second-stage polymerization reactor. To the second-stage polymerization reactor, ethylene 9 kg / hr, hexane 14 l / hr, butene-1 50 g / hr and hydrogen were continuously fed so as to obtain a polymer having an intrinsic viscosity shown in the table, and the temperature was 80 ° C. Polymerization was carried out at a residence time of 2.5 hours.

(Example 8) The procedure of Example 7 was repeated, except that the polymerization conditions in the first step and the second step were changed as shown in Table 1.

(Comparative Example 1) (1) Production of solid catalyst component 1.0 kg of magnesium diethoxide in 50 ml of n-heptane
(8.8 mol) and commercially available anhydrous magnesium sulfate 1.06 kg
(8.8 mol) is suspended and 1.5 kg of silicon tetrachloride (8.
8 mol) and 1.6 kg (35.2 mol) of ethanol were added and reacted at 80 ° C. for 1 hour. Then, 5 l (45 mol) of titanium tetrachloride was added and the reaction was carried out at 98 ° C for 3 hours. After the reaction, the solution was cooled and allowed to stand, and the supernatant was removed by a gradient method. Then a new n
-Heptane (100 l) was added, and the mixture was stirred, allowed to stand, and washed by removing the supernatant liquid three times. Then, 200 l of n-heptane was added to obtain a dispersion liquid of the solid catalyst component. The amount of titanium supported on this product was 42 mg-Ti / g-support as a result of determination by a colorimetric method.

(2) Production of ethylene copolymer As the catalyst component, the solid catalyst component of the above (1) is converted into Ti.
1.8 mmol / hr, diethyl aluminum chloride 49.7 mmol / hr, triethyl aluminum 4.3
An ethylene copolymer was obtained in the same manner as in Example 7, except that the ethylene copolymer was supplied at a mmol / hour.

(Comparative Example 2) Ethylene 5 kg / hr, hexane 15 l / hr and hydrogen were continuously fed to a 200 l first-stage polymerization reactor so as to obtain a polymer having an intrinsic viscosity shown in Table 1. The solid catalyst component used in Example 1 was 0.5 mmol / equivalent to Ti.
The amount of triisobutylaluminum was 15.0 mmol / hour, and the polymerization was carried out under the conditions of a polymerization temperature of 80 ° C. and a residence time of 4 hours. The contents of the polymerization vessel were continuously introduced into a hydrogen degassing tank at a predetermined rate, hydrogen was separated, and then introduced into a 200-liter second-stage polymerization reactor. In the second-stage polymerization vessel, ethylene 5 kg / hour,
Hexane 15 l / h, butene-1 100 g / h and hydrogen were continuously fed so that a polymer having the intrinsic viscosity shown in the table was obtained, and polymerized under the conditions of 80 ° C and a residence time of 2.5 hours to obtain ethylene Got united. The results of measuring the physical properties of this product are shown in the table.

(Comparative Example 3) Using the solid catalyst component produced in Comparative Example 1, the first stage was polymerized in the same manner as in Example 7. The contents of the polymerization vessel were continuously introduced at a predetermined rate into a 200-liter second-stage polymerization reactor. Two
In the second stage polymerization reactor, ethylene 5 kg / hour, hexane 2 l
/ Hour and hydrogen are continuously fed so that a polymer having the intrinsic viscosity shown in Table 1 is obtained, and the residence time at 80 ° C. is 4
Polymerization was carried out under the condition of time. The contents of the polymerization vessel were continuously introduced into a hydrogen degassing tank at a predetermined rate, and after hydrogen was separated, they were introduced into a 200-liter third-stage polymerization reactor. Ethylene (3.75 kg / hour), hexane (12 l / hour), butene (142 g / hour) and hydrogen were continuously fed to the third-stage polymerization reactor so that a polymer having an intrinsic viscosity shown in Table 1 was obtained, Polymerization was carried out at 80 ° C. for a residence time of 2.5 hours.

(Comparative Example 4) 5 kg / hour of ethylene, 15 l / hour of hexane and hydrogen were continuously fed to a 200 l first-stage polymerization reactor so that a polymer having an intrinsic viscosity shown in Table 1 was obtained. The solid catalyst component used in Example 1 was 1.4 mmol in terms of Ti /
Diethyl aluminum chloride was supplied at 39.2 mmol / hour and triethyl aluminum was supplied at 3.4 mmol / hour for polymerization for 80 hours at a polymerization temperature of 4 hours for polymerization. The contents of the polymerization vessel were continuously introduced into a hydrogen degassing tank at a predetermined rate, hydrogen was separated, and then introduced into a 200-liter second-stage polymerization reactor. In the second-stage polymerization vessel, ethylene 5 kg / hour,
Hexane 15 l / h, butene-1 100 g / h and hydrogen were continuously fed so that a polymer having the intrinsic viscosity shown in the table was obtained, and polymerized under the conditions of 80 ° C and a residence time of 2.5 hours to obtain ethylene Got united. Table 2 shows the results of measuring the physical properties of this product.

[Advantages of the Invention] Since the present invention is a two-step polymerization as described above, it has effects that the polymerization is easily controlled, the productivity is high, and the equipment cost is low.

Further, the ethylene copolymer composition produced by the present invention has good pinch-off fusion bondability, and has a high melt tension, so that it is excellent in hollow moldability, and further has an effect that mechanical properties are also excellent. is there.

[Brief description of drawings]

FIG. 1 is a flow chart showing one embodiment of the method of the present invention.

Claims (1)

[Claims] 1. A solid catalyst component containing tetravalent titanium, tetravalent zirconium, magnesium and halogen and a catalyst containing an organoaluminum compound as a main component, and (a) step: at a temperature of 30 to 80 ° C. And other α-olefin content is 10% by weight or less, and the intrinsic viscosity [η] is 10 to 40 dl / g
Of ethylene homopolymer or copolymer of 1 to 23% by weight based on the total amount of polymerization (b) step: at a temperature of 60 to 100 ° C, the content of other α-olefins is 15 Weight% or less, intrinsic viscosity [η] is 1.0 to 5.0
The process of producing an ethylene homopolymer or copolymer of dl / g at a ratio of 77 to 99% by weight of the total polymerization amount is carried out in any order. The intrinsic viscosity [η] is 3.0. ~ 5.0 dl / g, density 0.940 ~ 0.961 g / cm ³ A method for producing an ethylene copolymer composition.