JP3286850B2 - Method for producing polyethylene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyethylene using a Ziegler-type catalyst having extremely high activity. More specifically, a temperature of 150 ° C. or more, 5
The present invention relates to a novel method for producing polyethylene, which comprises homopolymerizing ethylene or copolymerizing ethylene and an α-olefin using a catalyst component having extremely high catalytic activity under a pressure condition of 0 kg / cm ² or more.

[0002]

2. Description of the Related Art Conventionally, as one method for producing an ethylene (co) polymer, a method of polymerizing ethylene in the presence of a so-called Ziegler-type catalyst combining a transition metal compound and an organometallic compound, or ethylene and A method of copolymerizing with an α-olefin is known. Among them, as a Ziegler-type catalyst, it is advantageous to combine a compound of titanium, zirconium and vanadium with an organoaluminum compound in terms of catalytic activity and the molecular weight, molecular weight distribution, copolymer composition, etc. of the resulting polyethylene. Has been used in many ways.

[0003] When the manufacturing methods are classified by process,
Slurry polymerization, polymerization in which the polymer is kept in a particle state under the temperature condition below the melting point of polyethylene, gas phase polymerization, solution polymerization in which the polymerization is carried out at a temperature above the melting point, and high-temperature high-pressure polymerization are known. ing. Among these polymerization processes, the solution polymerization method and the high-temperature high-pressure polymerization method can effectively utilize the heat of polymerization due to the exothermic reaction, and are advantageous in energy. On the other hand, in the slurry polymerization method and the gas phase polymerization method, in low-density polyethylene produced by copolymerization with an α-olefin, it is difficult to keep the copolymer particles in a stable state because the crystallinity of the copolymer is low, Since the reactivity of the higher α-olefin is low, it is difficult to produce a higher α-olefin copolymer having excellent physical properties, and the range of products that can be industrially produced is limited. On the other hand, the solution polymerization method and the high-temperature high-pressure polymerization method do not take a particle state or increase the reactivity of α-olefin by a high-temperature reaction,
It is possible to produce high-quality low-density polyethylene in a wide range without the above-mentioned restrictions.

However, when a conventional Ziegler-type catalyst using a combination of a transition metal compound component and an organometallic compound component is applied to the solution polymerization method or the high-temperature high-pressure method, the transition metal compound is overreduced by the organoaluminum compound used at the time of polymerization. It is known that the polymerization activity is reduced by the reaction.

In view of the above, a polymerization method for homopolymerizing ethylene or copolymerizing ethylene with at least one α-olefin at a reaction temperature of 150 ° C. or higher corresponding to a melting point of a produced polymer which is advantageous in terms of process. Therefore, there is an industrial demand for a highly active catalyst that does not undergo overreduction by an organoaluminum compound.

Accordingly, the present inventors have conducted intensive studies to develop a highly active polymerization catalyst that utilizes the advantages of the solution polymerization method and the high-temperature and high-pressure polymerization method. It has been found that the catalyst exhibits surprising catalytic activity when used in the range, and the present invention has been completed.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to
At a temperature of 0 ° C. or higher and a pressure of 50 kg / cm ² or higher, that is, in a solution polymerization method or a high-temperature high-pressure polymerization method, the catalyst is highly active, does not require a catalyst removal step, has excellent comonomer reactivity, and has a high molecular weight. It is to provide a catalyst system capable of producing high polyethylene.

[0008]

The gist of the present invention is to provide a catalyst comprising a transition metal compound and an organometallic compound.
When producing polyethylene by homopolymerizing ethylene or copolymerizing ethylene and at least one α-olefin at a pressure of 50 kg / cm ² or more and a temperature of 150 ° C. or more, the following components are used as component (A): and metallic magnesium hydroxide organic compounds, R ¹ in (ii) general formula [TiO _a (OR ¹⁾ _{b] m} (provided that the general formula represents a hydrocarbon group having 1 to 20 carbon atoms.
a and b are numbers that are compatible with the valence of titanium when a ≧ 0 and b> 0 , and m is an integer. ) With the oxygen-containing organic compound of titanium, iodine, mercuric chloride,
From alkylogenates, organic acid esters and organic acids.
(Iii) a solid catalyst component obtained by reacting a reaction product obtained by the reaction with an organoaluminum halide compound in the presence of at least one member selected from the group consisting of: However,
Aluminoxane) except that the organoaluminum compound in the component (B) is used in a molar amount of 20 or less based on 1 gram atom of titanium contained in the component (A). And a method for producing polyethylene.

[0009]

The reactant used in the present invention is
(I) Metallic magnesium and organic hydroxideAs a compound
The following are listed.

First, in the case of using magnesium metal and an organic hydroxide compound, the magnesium metal can be in any of various shapes, such as powder, particles, foil or ribbon. As the compound, alcohols, organic silanols, and phenols are suitable.

As the alcohol, a linear or branched aliphatic alcohol, alicyclic alcohol or aromatic alcohol having 1 to 18 carbon atoms can be used.
Examples include methanol, ethanol, n-butanol, n-octanol, n-stearyl alcohol, i
-Propanol, sec-butanol, tert-butanol, 2-ethylhexanol, cyclopentanol, ethylene glycol and the like.

Further, the organic silanol has at least one hydroxyl group, and the organic group has 1 to 12 hydroxyl groups.
Alkyl groups, preferably having 1 to 6 carbon atoms, cycloalkyl groups, arylalkyl groups,
It is selected from an aryl group and an alkylaryl group. For example, the following example can be given. Trimethylsilanol,
Triethylsilanol, triphenylsilanol, t-
Butyldimethylsilanol and the like.

Further, phenols as phenols,
Cresol, xylenol, hydroquinone and the like.

In addition, when the solid catalyst component described in the present invention is obtained using magnesium metal, a substance which reacts with the magnesium metal or forms an addition compound, for example, for the purpose of accelerating the reaction, for example, Iodine, chloride 2
It is preferable to add one or more polar substances such as mercury, alkyl halides, organic acid esters, and organic acids.

[0015]

[0016]

As the oxygen-containing organic compound of titanium (ii), a compound represented by the general formula [TiO _a (OR ¹ ) _b ] _m is used. However, in the general formula, R ¹ is a linear or branched alkyl group having 1 to 20, preferably 1 to 10 carbon atoms, a cycloalkyl group, an arylalkyl group,
Aryl group, a hydrocarbon group such as an alkyl aryl group Table
You . a and b are numbers that are compatible with the valence of titanium when a ≧ 0 and b> 0 , and m is an integer. Above all, a
It is desirable to use an oxygen-containing organic compound in which is 0 ≦ a ≦ 1 and m is 1 ≦ m ≦ 6.

As a specific example, Ti (OC
_{2 H 5) 4, Ti (} O-n-C 3 H 7) 4, Ti (O-i-C
_{3 H 7) 4, Ti (} O-n-C 4 H 9) 4, Ti 2 O (O-i
—C ₃ H ₇ ) ₆ and the like. The use of oxygen-containing organic compounds containing several different hydrocarbon groups is also within the scope of the present invention. In addition, these titanium-containing compounds alone,
Alternatively, the use of a mixture of two or more of them is also within the scope of the present invention.

As the organoaluminum halide compound (iii), those represented by the general formula AlR ² _i X _3-i are used. However, in the general formula, R ²
Represents 1 to 20 hydrocarbon groups, X represents halogen, F,
Cl, Br, or I. i is a number satisfying 1 ≦ i <3. Preferably R ² is a linear or branched chain alkyl, cycloalkyl, arylalkyl, aryl, selected from alkyl aryl group. The organoaluminum halide compounds can be used alone or as a mixture of two or more.

Specific examples of the organoaluminum halide compound include, for example, ethyl aluminum dichloride,
n-propylaluminum dichloride, n-butylaluminum dichloride, i-butylaluminum dichloride, sesquiethylaluminum chloride, sesqui-i-butylaluminum chloride, sesquii-i-
Propyl aluminum chloride, sesqui-n-propyl aluminum chloride, diethyl aluminum chloride, di-i-propyl aluminum chloride, di-n-propyl aluminum chloride, di-i-butyl aluminum chloride, diethyl aluminum bromide, diethyl aluminum iodide, etc. can give.

These reactions are preferably performed in a liquid medium. Therefore, especially when these reactants are not liquid under the operating conditions, or when the amount of the liquid reactants is insufficient, the reaction can be carried out in the presence of an inert organic solvent.

As the inert organic solvent, any of those generally used in the art can be used, and examples thereof include aliphatic, alicyclic, or aromatic hydrocarbons, halogen derivatives thereof, and mixtures thereof. For example, isobutane, hexane, heptane, cyclohexane, benzene, toluene, xylene, monochlorobenzene and the like are preferably used.

Reactants (i) and (ii) used in the present invention
The amount of (iii) used is not particularly limited, but the ratio of magnesium atom (i) to titanium atom (ii) is 1: 0.
It is preferable to select the amount to be used so as to be from 01 to 1:20, preferably from 1: 0.1 to 1: 5. The amount of the reactant is such that the ratio of magnesium atoms to aluminum atoms in the organoaluminum halide compound (iii) is in the range of 1: 0.01 to 1: 100, preferably 1: 0.02 to 1:20. It is preferable to select In particular, 1: 0.05-
A 1: 1 range is preferred. Outside of these ranges, the result is low polymerization activity.

The reaction conditions for obtaining a reactant from the reactants (i) and (ii) are -50 to 300 ° C., preferably 0 to 2 ° C.
The reaction is carried out at a temperature of 00 ° C. for 0.5 to 50 hours, preferably 1 to 6 hours, in an inert gas atmosphere at normal pressure or under pressure. By carrying out the reaction under the conditions in such a range, it is possible to usually obtain a reactant in a homogeneous solution.

Further, when reacting the reactant (iii),
In a temperature range of 50 to 200C, preferably -30 to 100C, for 0.2 to 50 hours, preferably 0.5 to 5 hours.
It is performed for a time, in an inert gas atmosphere, or under pressure.

The solid catalyst component (A) thus obtained is in the form of particles or colloid insoluble in a solvent used as a diluent, and may be used as it is. The remaining unreacted substances and by-products are removed by a gradient method, washed several times with an inert solvent, and used by suspending in an inert solvent. Also, isolated after washing,
Those obtained by removing the solvent under normal pressure or reduced pressure can also be used.

Further, the solid catalyst component (A) can be used as a component obtained by adding a small amount of an α-olefin in advance to make the catalyst particles finer.

The catalyst component (B) used in the present invention
Is represented by the general formula: AlR ³ _j (OR ⁴ ) _k X _3-k (wherein, R ³
And R ⁴ represents an alkyl group having 1 to 20 carbon atoms, X represents a halogen atom, and j and k represent 0 <j ≦
3,0 ≦ k ≦ 2,0 organoaluminum compound represented by the <represents a number comprised j + k ≦ 3) and the like.

The above general formula AlR ³ _j (OR ⁴ ) _k X
Specific examples of the organoaluminum compound represented by _3-k include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum; Alkyl aluminum halides such as chloride, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, diethyl aluminum monobromide, diisopropyl aluminum monobromide, dimethyl aluminum ethoxide, diethyl aluminum ethoxide, diethyl aluminum propoxide , Dieci Aluminum butoxide, diethyl aluminum phenoxide, alkyl aluminum alkoxides such as ethyl aluminum diethoxide and the like.

[0030]

These organoaluminum compounds are used alone or as a mixture of two or more.

The amount of the catalyst component (B) used is a molar amount of 20 or less, preferably 1 or more and 10 or less, based on 1 gram atom of titanium contained in the solid catalyst component (A). . In the present invention, it is important to strictly control the ratio of the amounts of the solid catalyst component (A) and the catalyst component (B) to be used. Characteristics cannot be fully exhibited.

The polymerization of the present invention is a homopolymerization of ethylene or a copolymerization of ethylene with at least one α-olefin. As the α-olefin used for copolymerization with ethylene, those having 3 to 20 carbon atoms are preferable, and specific examples thereof include propylene, 1-butene, 1-hexene,
4-Methyl-1-pentene, 1-octene, 1-decene and the like and mixtures thereof are used.

The polymerization of ethylene is carried out at a temperature of 150 ° C. or more, preferably 160 to 300 ° C.,
As a polymerization medium, an inert solvent or the monomer itself is used.

In the solution polymerization using an inert solvent, aliphatic hydrocarbons such as hexane, heptane, octane, nonane, decane, undecane, dodecane and mixtures thereof, aromatic hydrocarbons such as benzene, toluene, etc. Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane are used. Polymerization pressure is 50-20
0 Kg / cm ² and the residence time ranges from 1 minute to 6 hours, preferably from 4 minutes to 3 hours.

In the high-temperature and high-pressure polymerization in which the monomer itself is used as a polymerization medium, an ethylene high-pressure radical polymerization apparatus or the like can be generally used.
00 kg / cm ² , preferably 400 to 1500 kg /
cm ² , residence time 5 to 600 seconds, preferably 10 to 15
This is performed within a range of 0 seconds.

In the present invention, the molecular weight of the polymer can be controlled by adjusting the reaction temperature, but can be easily controlled by allowing hydrogen to be present in the polymerization zone. Since the amount of hydrogen varies depending on the polymerization conditions, the desired molecular weight of the ethylene polymer, and the like, it is necessary to appropriately adjust the amount.

[0038]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.

In the examples, MI represents a melt index, which is measured at 190 ° C. under a load of 2.16 kg based on JIS K-6760. The density is
The measurement was performed according to JISK-6760.

The polymerization activity was determined based on the amount of polymer produced per kg of the solid catalyst component (A) (kg) and the solid catalyst component (A)
Represents the amount of polymer produced (kg) per gram of transition metal component in the polymer.

Example 1 [Preparation of solid catalyst component (A)] Stirrer, reflux condenser,
7 g (0.29 mol) of metallic magnesium powder was placed in a 1-liter flask equipped with a dropping tube and a thermometer, and 0.35 g of iodine and 42.9 g (0.60 mo) of butanol were added thereto.
l) and 39.2 g of titanium tetrabutoxide (0.1
After adding 15 mol), the temperature was raised to 90 ° C., and the mixture was stirred for 2 hours under a nitrogen seal while removing generated hydrogen gas. Subsequently, the temperature was raised to 140 ° C. and the reaction was performed for 2 hours.
Thereafter, 490 ml of hexane was added to obtain a reaction product of a homogeneous solution containing magnesium and titanium.

Then, the obtained solution was converted to 0.10 in terms of Mg.
mol is placed in a separately prepared 1 liter flask, and at 45 ° C., 50% of i-butylaluminum dichloride is added.
After adding 223 ml (0.60 mol) of a hexane solution, the temperature was raised to 60 ° C., and the mixture was stirred for 1 hour to obtain a solid catalyst component (A).

After thoroughly washing the solid catalyst component (A) with hexane until titanium and aluminum are no longer detected in the liquid, the solid catalyst component (A) is dried under a nitrogen stream at 40 ° C. to remove the solid catalyst component (A). I took it out. The titanium content in the solid catalyst component (A) was 6.8%.

0.2 g of the obtained solid catalyst component (A) was
The slurry was dispersed in 100 ml of a solvent mainly containing isoparaffin having 10 to 11 carbon atoms (IP-1620 manufactured by Idemitsu Petrochemical Co., Ltd.) to prepare a slurry of the solid catalyst component (A).

[Ethylene polymerization] A stainless steel autoclave with an induction stirrer having a capacity of 2 l was purged with nitrogen.
Add 1200 ml of IP-1620 and stir for 22 minutes.
The temperature was raised to 0 ° C. The vapor pressure of the solvent is about 1.0 kg /
cm ² G, but ethylene at a total pressure of 60.0 kg / cm
² G, and the slurry of the solid catalyst component (A) (solid catalyst component (A) 1 mg, titanium atom 0.0
014 mmol) and triethylaluminum (0.014 mmol) as the catalyst component (B) were added to initiate polymerization. When ethylene was continuously introduced and polymerization was carried out for 4 minutes while keeping the total pressure constant, 84.9 g of a polymer was obtained. The polymerization activity per solid catalyst component (A) is 8
It was 4.9 kg / g. The activity per transition metal component corresponded to 1249 Kg / g. MFR is 0.16 g /
10 minutes, and the melting point of the polymer was 135 ° C.

Examples 2 and 3, Comparative Examples 1 and 2 [Ethylene polymerization] As shown in Table 1, the solid catalyst component (A) prepared in Example 1 and triethylaluminum were used as the catalyst component (B). The polymerization of ethylene was carried out.

[0047]

[Table 1] Examples 4 to 7 The same as Example 1 except that the reactants of the homogeneous solution containing magnesium and titanium prepared in Example 1 were used, and the type and amount of the reactant (iii) were as shown in Table 2. The solid catalyst component (A) was prepared by the method, and ethylene was polymerized using triethylaluminum as the catalyst component (B). The results of the polymerization are also shown in Table 2.

[0048]

[Table 2] Example 8 1 mg (0.0%) of the solid catalyst component (A) prepared in Example 1
Polymerization was carried out under the same conditions as in Example 1 except that diethyl aluminum chloride (0.014 mmol) was used instead of triethyl aluminum as the catalyst component (B). As a result, the obtained polymer was 75.6 g, and the polymerization activity per solid catalyst component (A) was 75.6 Kg / g. The activity per transition metal component corresponded to 1112 Kg / g. MF
R was 0.21 g / 10 minutes.

Example 9 1 mg (0.0%) of the solid catalyst component (A) prepared in Example 1
Polymerization was performed under the same conditions as in Example 1 except that diethyl aluminum ethoxide (0.014 mmol) was used instead of triethyl aluminum as the catalyst component (B). As a result, the obtained polymer was 53.7 g, and the polymerization activity per solid catalyst was 53.7 kg / g. The activity per transition metal component corresponded to 790 kg / g. The MFR is 0.
It was 13 g / 10 minutes.

Example 10 [Preparation of solid catalyst component (A)] Stirrer, reflux condenser,
50 g (2.06 mol) of metallic magnesium powder was placed in a 3 l flask equipped with a dropping tube and a thermometer, and 2.5 g of iodine and 320 g (4.33 mol) of butanol were added thereto.
And titanium tetrabutoxide 350g (1.03mo
After the addition of 1), the temperature was raised to 90 ° C., and the mixture was stirred for 2 hours under a nitrogen blanket while removing generated hydrogen gas. Subsequently, the temperature was raised to 140 ° C. and the reaction was carried out for 2 hours. Thereafter, 1000 ml of hexane was added to obtain a reaction product of a homogeneous solution containing magnesium and titanium.

Then, the obtained solution was prepared separately.
1 reactor, and after adding 2400 ml of hexane,
After adding 3.8 kg (12.4 mol) of a 50% hexane solution of i-butylaluminum dichloride at 45 ° C., the temperature was raised to 60 ° C., and the mixture was stirred for 1 hour to obtain a solid catalyst component (A).

This solid catalyst component (A) was sufficiently washed with hexane in the same manner as in Example 1. A part of the obtained solid catalyst was taken out, dried under a stream of nitrogen, and the titanium content was measured to be 6.7%.

Hexane 6 was added to the obtained solid catalyst component (A).
300 ml of hexane slurry was added, and 370 ml of hexene was added, followed by stirring for 8 hours to prepare a catalyst slurry for polymerization.

[Ethylene polymerization] Triethylaluminum was used as the solid catalyst component (A) and the catalyst component (B) obtained above in a vertical cylindrical reactor equipped with a stirrer, and ethylene and 1-hexene were continuously supplied. And set the temperature in the polymerization vessel to 1
The polymerization was carried out while maintaining the pressure at 80 ° C. and the pressure at 800 kg / cm ² G. The average residence time in the polymerization vessel was 50 seconds, the molar ratio of ethylene to 1-hexene was 65/35, the catalyst was supplied by 0.375 g of the solid catalyst component (A), and triethylaluminum (1. (57 mmol) was supplied at a rate per hour, and polymerization was carried out for 8 hours. As a result, 24.9 kg of an ethylene copolymer was obtained per hour. The polymerization activity per solid catalyst component (A) is 6
6.4 kg / g, and the activity per transition metal component is 9
It corresponded to 91 kg / g. MI is 2.5 g / 10 min, the melting point of the polymer is 123 ° C. and the density is 0.925 g / min.
cm ³ .

Examples 11 to 13 Polymerization was carried out using triethylaluminum as the solid catalyst component (A) and the catalyst component (B) prepared in Example 10. The polymerization of ethylene and hexene was carried out in the same manner as in Example 10 except that the polymerization conditions were as shown in Table 3. The results of the polymerization are also shown in Table 3.

[0056]

[Table 3]

[0057]

[0058]

[0059]

[0060]

[0061]

The first effect of the present invention is that a polymer having a very high polymerization activity per transition metal and per solid catalyst and which does not require a deashing step for removing the catalyst can be obtained. Because of its high activity, there is no need to worry about coloring or odor of the product, and it is not necessary to form a polymer, which is extremely economical.

The second effect of the present invention is that the catalyst has excellent thermal stability. Therefore, the active life is relatively long even at high temperatures.

The third effect of the present invention is that the molecular weight of the obtained copolymer can be increased. Therefore, for hollow molding,
A polymer suitable for film molding can be obtained, and the surface properties of the molded article can be improved.

The fourth effect of the present invention is that the copolymerizability with other α-olefin (comonomer) is good.
The polymerization conversion of the comonomer is higher than other catalyst systems.
(A small amount of α-olefin to be copolymerized is required.)

[Brief description of the drawings]

FIG. 1 is a catalyst preparation diagram (flow chart) in the present invention.
Is shown.

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08F 4/60-4/70

Claims (1)

(57) [Claims] An ethylene homopolymer or a copolymer of ethylene and at least one α-olefin at a pressure of 50 kg / cm ² or more and a temperature of 150 ° C. or more in the presence of a catalyst comprising a transition metal compound and an organometallic compound. In producing polyethylene by polymerization, (A) components include (i) metallic magnesium and an organic hydroxide compound, and (ii) a general formula [TiO _a (OR ¹ ) _b ] _m (wherein R in the general formula ¹ represents a hydrocarbon group having 1 to 20 carbon atoms.
a and b are numbers that are compatible with the valence of titanium when a ≧ 0 and b> 0 , and m is an integer. ) With the oxygen-containing organic compound of titanium, iodine, mercuric chloride,
From alkylogenates, organic acid esters and organic acids.
(Iii) a solid catalyst component obtained by reacting a reaction product obtained by the reaction with an organoaluminum halide compound in the presence of at least one member selected from the group consisting of: However,
Aluminoxane) (excluding aluminoxane), wherein the organoaluminum compound in the component (B) is used in a molar amount of 20 or less based on 1 gram atom of titanium contained in the component (A). A method for producing polyethylene.