JP2681701B2 - Method for producing polyethylene copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement in a method for producing a polyethylene copolymer. More specifically, the present invention has excellent properties that are excellent in polymerization activity, improve the copolymerizability of ethylene and α-olefin, and can provide a polyethylene copolymer having an improved balance of rigidity and ESCR. The present invention relates to a method for efficiently producing a polyethylene copolymer suitable for hollow moldings and films using a catalyst system.

[Prior Art] Conventionally, as a method for producing an ethylene-based polymer for hollow molded products and films, for example, a solid catalyst component obtained by reacting an organomagnesium compound, a titanium compound, a zirconium compound and an aluminum halide compound, A method of polymerizing ethylene or a mixture of ethylene and other α-olefins using a catalyst system composed of a combination with an organoaluminum compound is known (Japanese Patent Publication No. S55-8083, Japanese Patent Publication No. S56-151704). JP-A-52-39714, JP-A-63-301209).

Such a catalyst 4 system is highly active and can control the molecular weight distribution of the resulting polymer over a wide range, and is a polyethylene polymer or copolymer having a wide molecular weight distribution suitable for hollow molding and film molding. It has desirable properties such as being able to efficiently give. However, the polyethylene polymer or copolymer obtained by using the catalyst system has an insufficient balance between the rigidity of the molded product and the ESCR, and is not necessarily satisfactory for application to small and medium-sized blow grades. There was no problem.

[Problems to be Solved by the Invention] Under the circumstances, the present invention has excellent polymerization activity and improves the copolymerizability of ethylene and α-olefin,
Providing a method for efficiently producing a polyethylene copolymer suitable for hollow moldings and films by using a catalyst system having excellent properties that can give a polyethylene copolymer having an improved balance of rigidity and ESCR It was made for the purpose of doing.

[Means for Solving the Problems] As a result of intensive studies on the catalyst system having the above-mentioned excellent properties, the present inventors have found that the catalyst system comprises a specific magnesium compound, zirconium compound, titanium compound and organic aluminum halide compound. It has been found that the above object can be achieved by using a catalyst system in which a solid catalyst component is combined with an organoaluminum compound and a specific amount of an electron donor, and the present invention has been completed based on this finding.

That is, the present invention provides a magnesium compound represented by (A) (a) the general formula Mg (OR ¹ ) ₂ (I) (wherein R ¹ is an alkyl group having 1 to 3 carbon atoms), (B) General formula Zr (OR ² ) _n X ² _4-n (II) (In the formula, R ² is a hydrocarbon group, X ² is a halogen atom, and n is 0 to 0.
Zirconium compounds represented by 4 is a number of), (c) general formula _{^{Ti (OR 3) m X 3}} 4-m ...... (III) (R 3 in the formula is a hydrocarbon group, X ³ is a halogen atom , M is 0
A titanium compound represented by the formula ( ⁴ ) and (d) the general formula AlR ³ _k X ⁴ _3-k (IV) (wherein R ⁴ is a hydrocarbon group, X ⁴ is a halogen atom, and k is 1 to
The solid catalyst component consisting of an organoaluminum halide compound represented by the formula (2), (B) the organoaluminum compound, and (C) the titanium in the (A) component is used in an amount of 0.2 to 6.5 mol times. The present invention provides a method for producing a polyethylene copolymer, which comprises copolymerizing ethylene and an α-olefin in the presence of an electron donor in the proportion of.

 Hereinafter, the present invention will be described in detail.

In the method for producing a polyester copolymer of the present invention, a catalyst system comprising a combination of (A) a solid catalyst component, (B) an organoaluminum compound, and (C) an electron donor is used as a highly active catalyst.

In the preparation of the solid catalyst component (A), the magnesium compound used as the component (a) has a general formula Mg (OR ¹ ) ₂ (I) (wherein R ¹ has the same meaning as described above). And an average particle size of 50 μm or less is preferably used.

R ¹ in the general formula (I) must be an alkyl group having 1 to 3 carbon atoms, that is, a methyl group, an ethyl group, an n-propyl group or an isopropyl group, and in the case of an alkyl group having 4 or more carbon atoms. The magnesium compound is in the form of gel or liquid, and the object of the present invention cannot be achieved. Specific examples of the magnesium compound include magnesium dimethoxide, magnesium diethoxide, magnesium di-
Examples thereof include n-propoxide and magnesium diisopropoxide, and these may be used alone or in combination of two or more.

In the present invention, the magnesium dialkoxide of the component (a) has an average particle size of 50 μm or less, preferably 7 μm or less.
It is preferably in the range of up to 20 μm. If the average particle size exceeds 50 μm, the surface area becomes small, and the polymerization activity may decrease.

In the preparation of the solid catalyst component (A), the zirconium compound used as the component (b) is represented by the general formula Zr (OR ² ) _n X ² _4-n (II) (R ² , X ^{2 in the} formula And n have the same meanings as above). R ² in the general formula (II)
Is a hydrocarbon group, which may be a saturated group or an unsaturated group, may be a linear or branched one, or a cyclic group, and further may be sulfur, nitrogen, Although it may have a hetero atom such as oxygen, silicon, or phosphorus, a preferable hydrocarbon group has 1 to 1 carbon atoms.
There may be mentioned 20 alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl and aralkyl groups. Specific examples of R ² are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, pentyl group, hexyl group, heptyl group, octyl group, decyl group, Examples include octadecyl group, allyl group, butenyl group, cyclopentyl group, cyclohexyl group, cyclohexenyl group, phenyl group, tolyl group, benzyl group, phenethyl group and the like.

X ² in the general formula (II) is a fluorine atom,
A chlorine atom, a bromine atom and a halogen atom of an iodine atom, of which a chlorine atom and a bromine atom are preferable,
Particularly, a chlorine atom is preferred.

Typical examples of the zirconium compound represented by the general formula (II) include zirconium tetrachloride when n is 0, and monoethoxytrichlorozirconium and mono-n when n is 1. -Propoxytrichlorozirconium, mono-n-butoxytrichlorozirconium, di-n-propoxydichlorozirconium, etc., when n is 2, diethoxydichlorozirconium, di-n-propoxydichlorozirconium, di-n
-Butoxydichlorozirconium, etc., when n is triethoxymonochlorozirconium, tri-n-propoxymonochlorozirconium, tri-n-butoxymonochlorozirconium, etc., when n is 4, tetraethoxyzirconium, tetra-n- Examples thereof include propoxy zirconium and tetra-n-butoxy zirconium. One of these zirconium compounds may be used, or two or more thereof may be used in combination.

In the preparation of the solid catalyst component (A), the titanium compound used as the component (c) has a general formula of Ti (OR ³ ) _m X ³ _4-m (III) (R ³ and X ^{3 in the} formula And m have the same meanings as above). R ³ in the general formula (III) is a hydrocarbon group, which may be a saturated group or an unsaturated group, and may be a linear or branched one, or a cyclic group. It may also have a hetero atom such as sulfur, nitrogen, oxygen, silicon and phosphorus, but preferable hydrocarbon groups are alkyl groups having 1 to 20 carbon atoms, alkenyl groups and cycloalkyl groups. , Cycloalkenyl groups, aryl groups and aralkyl groups. Specific examples of R ³ are the same as those exemplified for R ² in the general formula (II). In addition, X ³ in the general formula (III)
Is a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and among these, a chlorine atom and a bromine atom are preferable, and a chlorine atom is particularly preferable.

Typical examples of the titanium compound represented by the general formula (III) include titanium tetrachloride and titanium tetrabromide when m is 0, and ethoxytrichlorotitanium when m is 1. n-propoxytrichlorotitanium, n
-Butoxytrichlorotitanium and the like, when m is 2, diethoxydichlorotitanium, di-n-propoxydichlorotitanium, di-n-butoxydichlorotitanium and the like are m
Is 3, triethoxymonochlorotitanium, tri-n-propoxymonochlorotitanium, tri-n-butoxymonochlorotitanium, and the like, and when m is 4, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisotitanium. Propoxy titanium, tetra-n-butoxy titanium, etc. are mentioned. These titanium compounds may be used alone or in combination of two or more.

In the preparation of the solid catalyst component (A), the organoaluminum halide compound used as the component (d) has the general formula AlR ³ _k X ⁴ _3-k (IV) (wherein R ⁴ , X ⁴ And k have the same meanings as above). R ⁴ in the general formula (IV)
Is a hydrocarbon group, which may be a saturated group or an unsaturated group, may be a linear or branched one, or a cyclic group, and further may be sulfur, nitrogen, Although it may have a hetero atom such as oxygen, silicon, or phosphorus, a preferable hydrocarbon group has 1 to 1 carbon atoms.
There may be mentioned 20 alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl and aralkyl groups. Specific examples of R ⁴ are the same as those exemplified for R ² in the general formula (II). Further, X ⁴ in the general formula (IV) is a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Among these, a chlorine atom and a bromine atom are preferable, and a chlorine atom is particularly preferable.

Typical examples of the organic aluminum halide compound represented by the general formula (IV) include methylaluminum dichloride, ethylaluminum dichloride, n-propylaluminium dichloride, isopropylaluminum dichloride, and n when k is 1. -Butylaluminum dichloride, isobutylaluminum dichloride and the like, and when k is 2, dimethylaluminum monochloride, diethylaluminum monochloride, di-n-propylaluminium monochloride, diisopropylaluminum monochloride, di-n-butylaluminium monochloride. , Diisobutylaluminum monochloride, and the like. These organic aluminum halide compounds may be used alone or in combination of two or more.

There is no particular limitation on the quantitative relationship of the components (a), (b), (c) and (d) used in the preparation of the (A) solid catalyst component in the present invention, (In the formula, [Mg], [Zr], [Ti] and [X] are magnesium, zirconium and gram equivalent, respectively,
It is desirable to prepare them by using them in such an allocation that the amount of titanium and halogen atoms) is satisfied, and by reacting them under the condition that the component (a) is not substantially dissolved.

If the value of is less than 0.05, the polymerization activity per unit weight of the catalyst tends to decrease, and the amount of halogen remaining in the polymer increases, which may lead to undesirable situations such as coloring and foaming. , 0.75, the polymerization activity per weight of the transition metal decreases, and the amount of the transition metal remaining in the polymer increases, which may cause problems such as coloring. Preferably, The value of is preferably in the range of 0.2 to 0.6. Also,
The condition of the relational expression (V) is also a condition in which the magnesium compound of the component (a) is substantially difficult to dissolve.

If the value of is greater than 3, there are too many components (b),
The component (c) may be too small and the polymerization activity per weight of the transition metal may decrease, and the amount of halogen used may increase, resulting in equipment corrosion due to unnecessary halogen and catalyst cost. May cause a rise.

In addition, the relational expression 0.2 <[Z
r] / [Ti] <20, preferably 0.5 ≦ [Zr] / [Ti] ≦ 10
It is desirable to use it in a ratio that satisfies the above. This [Z
When the value of r] / [Ti] is 0.2 or less, the molecular weight distribution of the obtained polymer may be too narrow, and when it is 20 or more, the polymerization activity tends to be low. Furthermore, regarding the usage allocation of the (a) component and the (d) component, the (a) component /
It is desirable to use both components so that the molar ratio of component (d) is more than 0.1 and less than 100, and preferably in the range of 1-40.

In the preparation of the solid catalyst component (A), the above (a),
The order of contacting the components (b), (c) and (d) is not particularly limited, but for example, a method of sequentially contacting the components (a), (b), (c) and (d). Alternatively, a method of sequentially contacting the components (a), (c), (b) and (d) is preferably used. This contact is usually performed in an inert solvent. As the inert solvent, for example, one or more hydrocarbon solvents selected from pentane, hexane, cyclohexane, heptane and the like are preferably used.

In addition, before adding the component (d), the component (a) and the component (b)
It is not preferable to heat the components or the components (a) and (c) in a mixed state because the catalyst components may adhere to the preparation tank. The component (d) is preferably added gradually so that the reaction proceeds uniformly while maintaining the temperature of the system in the range of 10 to 50 ° C. Since the activity tends to decrease, it is desirable to complete the addition within about 3 hours. If the temperature of the system in which the component (d) is added deviates from the above range, the amount of the polymer produced will be in the form of fine powder, which is not preferable.

In this way, the solid catalyst component of component (A) in the present invention is obtained in the reaction product liquid in a slurry state.
This slurry-like reaction product liquid may be used as it is as an ethylene copolymerization catalyst component, or the solid catalyst component is separated and recovered from the reaction product liquid, and then washed as necessary to obtain an ethylene copolymerization catalyst component. You may use as. As the separation method at this time, a known method, for example, a centrifugation method or a filtration method can be used, and the washing is performed using an inert hydrocarbon solvent such as pentane, hexane, cyclohexane, heptane or the like. be able to.

In the catalyst system of the present invention, the organoaluminum compound used as the component (B) is not particularly limited, but is generally represented by the general formula R ⁵ ₃ Al, R ⁵ ₂ AlX ⁵ , R ⁵ ₃ Al ₂ X ⁵ ₃ , R ⁵ _{2 The} one represented by AlOR ⁶ is used. In the formula, R ⁵ and R ⁶ are hydrocarbon groups such as an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkenyl group, an aryl group and an aralkyl group, and X ⁵ is a halogen atom such as a chlorine atom or a bromine atom. .

Examples of such an organoaluminum compound include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, diethylaluminum monochloride, diisopropylaluminum monochloride, diisobutylaluminum monochloride, diethylaluminum monomethoxide, dimethylaluminum monoethoxide. , Diethyl aluminum monobutoxide, diethyl aluminum monophenoxide, ethyl aluminum dichloride, isopropyl aluminum dichloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride and the like. These compounds may be used alone or in combination of two or more.

The proportion of the solid catalyst component (A) and the organoaluminum compound (B) used is such that the proportion of aluminum atoms to the total of zirconium atoms of titanium atoms in the solid catalyst component is usually 1 to 1000 in atomic ratio, preferably Selected to be in the range of 10-200. The catalyst containing the solid catalyst component and the organoaluminum compound may be prepared separately from the composition of the polymerization reaction system described below, or may be prepared substantially simultaneously with the composition of the polymerization reaction system.

Examples of the electron donor used as the component (C) in the catalyst system of the present invention include esters such as carboxylic acid ester, carbonic acid ester, orthoester,
Silanes such as alkoxysilanes and aryloxysilanes, ethers, ketones, acid anhydrides, acid halides, acid amides, oxygenated compounds such as phosphites, tertiary amines, nitriles Among them, ethers, especially aromatic alkoxy compounds are preferable.

Specific examples of the aromatic alkoxy compound include m-
Methoxytoluene, o-methoxyphenol, m-methoxyphenol, 2-methoxy-4-methylphenol, vinylanisole, p- (1-propenyl) anisole, p-allylanisole, 1,3-bis (p-methoxyphenyl) Monoalkoxy compounds such as -1-pentene, 5-aryl-2-methoxyphenol, 4-aryl-2-methoxyphenol, 4-hydroxy-3-methoxybenzyl alcohol-methoxybenzyl alcohol, nitroanisole and nitrophenetole, o Dialkoxy compounds such as -dimethoxybenzene, m-dimethoxybenzene, p-dimethoxybenzene, 3,4-dimethoxytoluene, 2,6-dimethoxyphenol, 1-aryl-3,4-dimethoxybenzene and 1,3,5- Trimethoxybenzene, 5-aryl 1,2,3-trimethoxybenzene, 1,2,3-trimethoxy-5- (1-propenyl) benzene, 1,2,4-trimethoxy-5- (1-propenyl) benzene, 1,2,3- Trimethoxybenzene, 1,
Examples include trialkoxy compounds such as 2,4-trimethoxybenzene, among which dialkoxy compounds and trialkoxy compounds are preferred. These alkoxy group-containing aromatic compounds may be used alone or in combination of two or more.

Regarding the use ratio of the solid catalyst component (A) and the electron donor (C), the electron donor is 0.2 to 6.5 mol times, preferably 1 to 5 mol times the titanium atom in the solid catalyst component. It can be used in such a ratio that If the amount used is less than 0.2 mol times, the effect of increasing the number of branches by the addition of an electron donor may be insufficient, and if it exceeds 6.5 mol times, the catalytic activity tends to decrease.

The ethylene copolymerization catalyst of the present invention contains the solid catalyst component (A) component, the organoaluminum compound (B) component, and the electron donor (C) component prepared as described above. Therefore, the order of addition of these components is not particularly limited, and the components (A), (B) and (C) may be contacted at the same time, or the components (B) and (C) may be added together. May be brought into contact with the component (A), or the components (A) and (C) may be brought into contact with each other and then brought into contact with the component (B).

Next, a preferred example of the method for copolymerizing ethylene and α-olefin in the present invention will be described. First, in an inert solvent, for example, a hydrocarbon solvent such as pentane, hexane, cyclohexane, heptane, (A ) Solid contact component, component (B), organoaluminum compound (B), and component (C), an electron donor, are added in predetermined amounts, and then a mixture of ethylene and another α-olefin is introduced into the system. And polymerize. The polymerization method and system are not particularly limited, and for example, any method such as a solution polymerization method, a suspension polymerization method, a gas phase polymerization method can be used, and both continuous polymerization and discontinuous polymerization are possible.

Regarding the blending ratio of each component for constituting the reaction system, in the case of solution polymerization and suspension polymerization, the solid catalyst component of the component (A) has a total of titanium atoms and zirconium atoms. It is usually used in an amount of 0.0005 to 10 mg atom / m, preferably 0.001 to 1 mg atom / mole, and the organoaluminum compound as the component (B) has an Al / (Ti + Zr) atomic ratio of usually 1 to 1000 as described above. , Preferably in the range of 10 to 200.

The pressure of the reaction system is usually normal pressure to 100 kg / cm ² ,
It is preferably in the range of ^{3 to} 50 kg / cm ² , and the reaction temperature is usually selected in the range of 20 to 200 ° C, preferably 50 to 150 ° C.
The reaction time is generally 5 minutes to 10 hours, preferably about 30 minutes to 5 hours.

The molecular weight during the polymerization is controlled by the polymerization temperature, the catalyst concentration,
It is possible by adjusting polymerization conditions such as catalyst composition and catalyst / monomer ratio, but it is more effective to carry out in the presence of hydrogen.

In the present invention, other α-olefins copolymerized with ethylene include, for example, propylene, butene-1, pentene-1, octene-1, 4-methylpentene-1,
Vinyl cyclohexane etc. are mentioned. These α-
The olefins may be used alone or in combination of two or more.

Further, in the present invention, in the catalyst system or the polymerization reaction system, in addition to each of the catalyst components described above, if desired, an organometallic compound such as organozinc, or during the polymerization of ethylene by a Ziegler-based catalyst. Alternatively, various additives that are usually added may be added to copolymerize ethylene and α-olefin.

The polyethylene copolymer thus produced can be recovered by a conventional method. According to the production method of the present invention, the activity of the catalyst used is remarkably high, and the monomer / catalyst ratio can be sufficiently increased.
It is not always necessary to provide a special decatalysis step.

FIG. 1 is a flowchart showing an example of the embodiment of the present invention.

[Examples] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

In addition, the physical properties of the obtained polymer were determined as follows.

(1) Intrinsic viscosity [η] Measured in decalin at 135 ° C.

(2) Tensile elastic modulus It was measured according to JIS K-7113.

(3) ESCR According to ASTM D-1693, an F ₅₀ value was determined at a temperature of 50 ° C. using a 10 wt% aqueous solution of Nissan Nonion as a surfactant.

(4) Number of branches introduced Soxhlet extraction in boiling hexane for 6 hours, and then 1,2,4-trichlorobenzene / deuterated benzene (9: 1) mixed solvent was used, and measurement was performed 10,000 times at C ¹³ NMR 50 MHz. .

Examples 1 to 10 and Reference Example 1 (1) Preparation of solid catalyst component 50 ml of hexane in which 6.5 mmol of tetrabutoxyzirconium and 6.5 mmol of tetrabutoxytitanium were dissolved
Was mixed with 150 ml of a hexane slurry containing 10 g of Mg (OEt) ₂ having an average particle size of 12 μm at a temperature of 20 ° C. with stirring.
After dropwise over a period of between minute to a 50 wt% hexane diluted solution 92ml of EtAlCl _2, at a temperature of 35 ° C. with stirring
It was added dropwise over 120 minutes, and further reacted for 120 minutes under reflux. Next, it was washed with dry hexane until chlorine was not detected in the liquid, and the total volume was adjusted to 50 ml with hexane.

(2) Production of ethylene copolymer n-Hexane 3 was added to an autoclave with a capacity of 7 which was sufficiently replaced with nitrogen, and the temperature was raised to 60 ° C, after which ethylene was added at 0.5 kg / cm ² · G. Introduced, and further charged with butene-17.0 g.

Then, a solid catalyst component containing 0.10 mmol of titanium prepared in (1) above, 3.0 mmol of triisobutylaluminum and an electron donor of the kind and amount shown in Table 1 were added, and the total pressure was 3.0 kg / While feeding ethylene so as to maintain cm ² · G, 10% by weight of the total amount of polymerization was polymerized, and then the inside of the autoclave was sufficiently replaced with nitrogen,
Residual ethylene gas and butene-1 were removed from the autoclave.

Next, n-hexane 2 is added to this, the temperature is raised to 80 ° C., hydrogen 3.6 kg / cm ² · G and ethylene 1.5 kg / cm ² · G are introduced, and then the total pressure is 6.0 kg / cm ² · G. 90% by weight of the total amount of polymerization was polymerized while feeding ethylene so as to maintain the temperature at 1.

 The polymerization conditions and the polymerization results are shown in Table 1.

Comparative Examples 1 to 3 (1) Preparation of solid catalyst component A solid catalyst component was prepared in the same manner as in the examples.

(2) Production of ethylene copolymer An ethylene copolymer was produced in the same manner as in Example except that the kind and amount of the electron donor were changed as shown in Table 1.

 The polymerization conditions and the polymerization results are shown in Table 1.

[Effect of the Invention] According to the method of the present invention, a solid catalyst component composed of a magnesium compound, a zirconium compound, a titanium compound and an organic aluminum halide compound, an organic aluminum compound, and an electron donor are used as a copolymerization catalyst of ethylene and an α-olefin. By using a highly active catalyst in combination with, it is possible to efficiently produce a polyolefin copolymer having an excellent balance between rigidity and ESCR, and
The amount of α-olefin used is reduced, and a cost advantage is obtained.

The polyethylene copolymer obtained by the method of the present invention is preferably used, for example, for hollow molded articles and films,
It can also be applied to small and medium blow grades.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of the embodiment of the present invention.

Claims (1)

(57) [Claims] 1. A magnesium compound represented by (A) (a) a general formula Mg (OR ¹ ) ₂ (wherein R ¹ is an alkyl group having 1 to 3 carbon atoms), and (b) a general formula Zr. (OR ² ) _n X ² _4-n (wherein R ² is a hydrocarbon group, X ² is a halogen atom, and n is 0 to
Zirconium compounds represented by 4 is a number of), (c) general formula _{^{Ti (OR 3) m X 3}} 4-m (R 3 in the formula is a hydrocarbon group, X ³ is a halogen atom, m is 0
A titanium compound represented by the formula: (d) General formula AlR ³ _k X ⁴ _3-k (wherein R ⁴ is a hydrocarbon group, X ⁴ is a halogen atom, and k is 1 to
The solid catalyst component consisting of an organoaluminum halide compound represented by the formula (2), (B) the organoaluminum compound, and (C) the titanium in the (A) component is used in an amount of 0.2 to 6.5 mol times. A method for producing a polyethylene copolymer, which comprises copolymerizing ethylene and an α-olefin in the presence of an electron donor having a ratio of 1.