JPH0780969B2 - Method for producing ethylene-based polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an ethylene-based polymer, and more particularly, to the efficiency of an ethylene-based polymer including linear low density polyethylene by high temperature solution polymerization. Regarding a good manufacturing method.

[Problems to be Solved by Prior Art and Invention]

Conventionally, as a method for producing a linear low density polyolefin, a high pressure ion method, a gas phase polymerization method, a suspension polymerization method, and a high temperature solution polymerization method are known. Among these methods, the high-pressure ion method and the gas phase polymerization method have a difficulty in using a higher α-olefin, and the suspension polymerization method has a problem in producing a low density product. Therefore, it can be said that the high temperature solution polymerization method is excellent as a method for producing the linear low-density polyolefin.

Generally, in the solution polymerization method, since the produced polymer is dissolved in a solvent and the liquid viscosity in the polymerization system increases, it is desirable to carry out the polymerization at a temperature as high as possible (155 ° C. or higher) in the operation of the apparatus. However, all of the catalysts used in the conventionally known methods have insufficient activity at high temperatures, and the physical properties of the copolymers obtained by high temperature solution polymerization so far are not yet satisfactory.

A supported catalyst has been developed as a catalyst for high temperature solution polymerization in order to improve the activity (see Japanese Patent Publication No. 59-52643).
The production process is complicated, and most of them require a washing process in order to remove unnecessary titanium components from the prepared catalyst. Therefore, a catalyst manufacturing facility is required and a large amount of cleaning solvent is required.

Some proposals have hitherto been made for the purpose of easily obtaining a catalyst having high activity at high temperature. Among them
46-31968 and 50-39117 report catalyst systems that can achieve relatively high activity without preparing the catalyst in advance. However, in any of these cases, none of them can express a sufficiently high activity, which causes a new defect such as a change in hue of the produced polymer.

JP-A-60-42405 discloses that in order to improve the activity,
It has been proposed to use alcohol as the activator. However, the addition of a small amount of alcohol does not exert an effect, and when it is added in a slight excess, it acts as a catalyst poison and loses its activity. Thus, the range of effects of alcohol is very narrow. This causes an increase in the raw material cost of the catalyst and a hindrance to stable operation.

Therefore, the present inventor has a sufficiently high activity even at high temperature,
We have developed a catalyst system that does not require complicated preparation steps and that does not require washing and removal of residual components in the produced polymer. In order to develop a method capable of producing an ethylene-based polymer,

[Means for solving problems]

As a result, a catalyst composed of a specific organotitanium compound and a reaction product of an organomagnesium compound, an organoaluminum compound and an ether compound is used as a catalyst for high temperature solution polymerization under heating conditions under which a produced polymer is dissolved in a reaction medium. It has been found that the above-mentioned problems can be solved by carrying out the polymerization with. The present invention has been completed based on such findings.

That is, in the present invention, when ethylene is homopolymerized or copolymerized with other α-olefin in the presence of a catalyst in a reaction medium to produce an ethylene-based polymer, (A) a general formula Ti (OR ¹ ) _n X ¹ _4-n [in the formula, R ¹ is an alkyl group having 1 to 18 carbon atoms, 6 to 18 carbon atoms]
Represents a cycloalkyl group or an aryl group having 6 to 18 carbon atoms, and X ¹ represents a halogen atom. In addition, n is 0 ≦ n ≦ 4
Is a real number that satisfies. And a titanium compound represented by the formula (B) (a): MgR ² R ³ [wherein R ² is an alkyl group having 1 to 18 carbon atoms or 6 carbon atoms]
To 18 aryl groups, R ³ represents an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a halogen atom. ] An organomagnesium compound represented by the formula: (b) General formula R ⁴ _m AlX ² _3-m [wherein R ⁴ is an alkyl group having 1 to 20 carbon atoms, and 6 to 20 carbon atoms]
Represents an aryl group, an alkoxy group having 1 to 20 carbon atoms or an aryloxy group having 6 to 20 carbon atoms, and X ² represents a halogen atom. Further, m is a real number that satisfies 0 <m ≦ 3. When m is plural, each R ⁴ may be the same or different. The organic aluminum compound and (c) of the general formula R ⁵ OR ⁶ [wherein represented by], R ⁵ and R ⁶ represents an alkyl group or an aryl group having 6 to 18 carbon atoms having 1 to 18 carbon atoms. ] A method for producing an ethylene-based polymer, characterized by using a catalyst consisting of a reaction product of an ether compound represented by and performing polymerization or copolymerization under heating conditions in which the produced polymer dissolves in a reaction medium. It is provided.

In the method of the present invention, the polymerization is carried out using the catalyst composed of the components (A) and (B) as described above, and the transition metal component (A) is represented by the general formula Ti (OR ¹ ) _n X ¹ _4-n (I) [wherein R ¹ is an alkyl group having 1 to 18 carbon atoms, and 6 to 18 carbon atoms]
Represents a cycloalkyl group or an aryl group having 6 to 18 carbon atoms, and X ¹ represents a halogen atom. In addition, n is 0 ≦ n ≦ 4
Is a real number that satisfies. ] The titanium compound represented by is contained. Here, in the titanium compound represented by the general formula (I), when n is 0, the general formula TiX ¹ ₄ [wherein, X ¹ is the same as the above. ] Tetrahalogenated titanium represented by, specifically, for example, TiCl ₄ , TiBr ₄ , and TiI ₄ , and when n is 1, the general formula Ti (OR ¹ ) X ¹ ₃ [in the formula, R ¹ And X ¹ is the same as the above], specifically, for example, (CH ₃ O)
_{TiCl 3, (C 2 H 5} O) TiCl 3, (C 3 H 7 O) TiCl 3, (nC 4 H 9 O) trihalide alkoxy titanium TiCl ₃ or the like, or X ¹ is the corresponding bromine or iodine, Or a trihalogenated cycloalkyloxytitanium such as trichlorocyclohexoxytitanium or a trihalogenated aryloxytitanium such as trichlorophenoxytitanium, where n is 2, the general formula Ti (OR ¹ ) ₂ X ¹ ₂ [ In the formula, R ¹ and X ¹ are the same as the above], specifically, a titanium compound represented by, for example, (CH ₃ O) ₂ TiCl ₂ , (C ₂ H ₅ O) ₂ TiCl ₂ , (C ₃ H ₇ O) ₂ TiCl ₂ , (nC ₄
H ₉ O) ₂ TiCl ₂ etc. or corresponding dihalogenated dialkoxy titanium such as corresponding dihalogenated dialkoxy titanium or dichlorodicyclohexoxy titanium where X ¹ is bromine or iodine or dihalogenated diaryloxy such as dichlorodiphenoxy titanium Titanium and n is 3
In the case of, a titanium compound represented by the general formula (Ti (OR ¹ ) ₃ X ¹ [wherein, R ¹ and X ¹ are the same as the above], specifically, for example, (CH ₃ O)
₃ TiCl, (C ₂ H ₅ O) ₃ TiCl, (C ₃ H ₇ O) ₃ TiCl, (nC ₄ H ₉ O) ₃ TiCl, etc. or corresponding monohalogenated trialkoxy titanium in which X ¹ is bromine or iodine , Or monohalogenated tricycloalkyloxytitanium such as monochlorotricyclohexoxytitanium or monohalogenated triaryloxytitanium such as monochlorotriphenoxytitanium, and when n is 4, the general formula Ti (OR ¹ ) ₄ [wherein R ¹ is the same as the above], specifically, for example, tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetra-n-butoxy. Titanium, tetraalkoxytitanium such as tetraisobutoxytitanium or tetracycloalkyloxytitanium such as tetracyclohexoxytitanium, and tet Tetra aryloxy titanium such as phenoxy titanium and the like. Among these, tetraalkoxytitanium and Ti represented by the above general formula Ti (OR ¹ ) ₄
The titanium tetrahalide represented by X ₄ is preferable, and tetra-n-butoxy titanium and tetrachloro titanium are particularly preferable. These various titanium compounds may be used alone or in combination of two or more.

In the catalyst used in the method of the present invention, the component (B) is a reaction product of the components (a), (b) and (c) as described above. Here, the component (a) is represented by the general formula MgR ² R ³ [wherein R ² and R ³ are the same as described above]. ] An organomagnesium compound represented by, for example, dialkyl magnesium such as diethyl magnesium, dibutyl magnesium, butyl octyl magnesium, diamyl magnesium, dihexyl magnesium, dioctyl magnesium, ethyl butyl magnesium, butyl isopropyl magnesium, diphenyl magnesium, etc. Alkylaryl magnesium such as diaryl magnesium, ethylphenyl magnesium, etc., alkyl magnesium alkoxide such as butyl magnesium isopropoxide, aryl magnesium alkoxide such as phenyl magnesium propoxide, alkyl magnesium halide such as butyl magnesium chloride, amyl magnesium chloride, phenyl magnesium chloride Aryl etc. Magnesium halide and the like can be mentioned. Of these, dibutyl magnesium, dihexyl magnesium, butyl octyl magnesium and the like are particularly preferable. Even if the organomagnesium compound is used alone,
Also, two or more of the above may be mixed and used.

Further, the component (b) has a general formula R ⁴ _m AlX ² _3-m [wherein R ⁴ , X ² and m are the same as described above. ] An organic aluminum compound represented by, for example, the general formula R ⁴ ₃ Al, R ⁴ ₂ AlX ² , R ⁴ AlX ² ₂ , R ⁴ ₂ AlOR ⁷ , R ⁴ Al (OR ⁷ ) X ² , (OR
⁷ ) ₃ Al (provided that R ⁷ represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms) or R ⁴ ₃ Al ₂ X ²
_The compound represented by ₃ may be mentioned. More specifically, these compounds include triethyl aluminum, tripropyl aluminum, tributyl aluminum, triamyl aluminum, trioctyl aluminum, diethyl aluminum monochloride, dipropyl aluminum monochloride, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride, Dioctyl aluminum monochloride, ethyl aluminum dichloride, isopropyl aluminum dichloride, butyl aluminum dichloride, octyl aluminum dichloride, aluminum triethoxide, aluminum triisopropoxide, aluminum triisobutoxide, diethyl aluminum monoethoxide, dipropyl aluminum monoethoxide, Monoethyl monoethoxy door Miniumukurorido, monoethyl-isopropoxy aluminum chloride, ethyl aluminum sesquichloride, propyl aluminum sesquichloride, butyl aluminum sesquichloride and the like. Among these organic aluminum compounds, for example, diethyl aluminum monochloride, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride, dioctyl aluminum monochloride, ethyl aluminum dichloride, isopropyl aluminum dichloride, ethyl aluminum sesquichloride are preferable, and R ⁴ _{2 is} particularly preferable. A
Compounds represented by lX ² such as diethylaluminum monochloride and compounds represented by R ⁴ ₃ Al ₂ X ² ₃ such as ethylaluminum sesquichloride are preferred.

Next, the component (c) is represented by the general formula R ⁵ OR ⁶ [wherein R ⁵ and R ⁶ are the same as defined above. ] It is an ether compound represented by these, and is specifically a dialkyl ether, a diaryl ether, or an alkyl aryl ether. Specific examples of these ether compounds include, for example, diethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, di-n-amyl ether, diisoamyl ether, dineopentyl ether, di-n-. Hexyl ether, di-n-octyl ether, methyl n-butyl ether, methyl t-butyl ether, methyl isoamyl ether, ethyl isobutyl ether, ethyl n-butyl ether, anisole, phenetole and the like,
Of these, methyl t-butyl ether, anisole or methyl n-butyl ether is preferable.

The component (B) of the catalyst used in the method of the present invention is a reaction product of the above components (a), (b) and (c). This reaction product is obtained by mixing the components (a), (b) and (c), but there is no particular restriction on the order of addition of these three components, and the three components may be mixed simultaneously. Also, even if (c) is added after reacting (a) and (b) or (b) is added after reacting (a) and (c), (b) and (c) You may add (a) after making it react.

As a mixing ratio, (a) is added to the above-mentioned titanium compound (A), and (a) / (A) (atomic ratio of Mg / Ti) = 0.1 to 3
It is set to 0, preferably 0.5 to 20. If it is out of this range, the catalytic activity tends to be lowered. Also, (b) / (A)
(Al / Ti atomic ratio) = 1 to 120, preferably 5 to 80. When the atomic ratio of Al / Ti is less than 1, the activity of the catalyst is low, and even when it exceeds 120, the activity corresponding to the added amount is not improved. Furthermore, in the above range, the physical properties of the resulting ethylene polymer, particularly the film moldability, deteriorates.
Further, (c) / (A) (atomic ratio of O and Ti in the ether compound) = 0.1 to 200, preferably 0.2 to 100. If this ratio is too small, the activity tends to decrease.

When adding a catalyst to the reaction system, the components (A) and (B) are
It may be added simultaneously or sequentially from either one, but it was prepared by reacting the components (a) to (c) (B).
The component and the component (A) should be contacted. In the process of preparing the component (B), the component (A) and the component (a) are brought into contact with each other, and thereafter the components (b) and (c) are added, or after the components (b) and (A) are brought into contact with each other, ) And (c) are not added, sufficient activity cannot be obtained.

The catalyst composed of the components (A) and (B) can be used as a solution using an inert solvent, if necessary. Examples of the inert solvent that can be used include aliphatic hydrocarbons having 5 to 18 carbon atoms, alicyclic hydrocarbons, aromatic hydrocarbons, and the like. Specific examples include n- or i-pentane, hexane, heptane. , Octane, nonane, decane, tetradecane or cyclohexane, as well as benzene, toluene and xylene. Further, as the inert solvent, the above-mentioned various hydrocarbons can be used alone. Among these, preferable inert solvents include, for example, n-hexane.

When carrying out the process according to the invention, the components (A) and (B) are introduced separately into the reactor or, after premixing, are introduced into the reactor and then ethylene and, if desired, Accordingly, the α-olefin is supplied to start the polymerization.

In the present invention, the monomer may be ethylene alone, but other α-olefin may be used as a comonomer. α
The olefin includes, for example, a linear or branched monoolefin having 3 to 18 carbon atoms or an α-olefin substituted with an aromatic nucleus. Specific examples of the α-olefin that can be used include propylene, butene-1, hexene-1, octene-1, nonene-1, decene-1, undecene-.
1, linear olefin such as dodecene-1, 3-methylbutene-1; 3-methylpentene-1; 4-methylpentene-1;
2-ethylhexene-1; 2,2,4-trimethyl-pentene-
It is a branched monoolefin such as 1 or a monoolefin substituted with an aromatic nucleus such as styrene.

The polymerization reaction is carried out in a reaction medium, and can be carried out in a continuous system or a batch system under heating conditions in which a produced polymer is dissolved in the reaction medium. As the reaction medium, an inert solvent such as the above-mentioned aliphatic hydrocarbon, alicyclic hydrocarbon or aromatic hydrocarbon can be used.

The reaction temperature is a temperature at which the produced polymer is dissolved in the reaction medium, usually 140 ° C. or higher, particularly 180 to 220 ° C., that is, a temperature which is preferable for operating the apparatus because the liquid viscosity of the produced polymer solution is lowered.

Other polymerization conditions cannot be uniquely determined depending on the physical properties of the desired polymer, the type of monomer used, etc., but usually the catalyst concentration is 0.001 to 10 mmol / l in titanium concentration,
It is preferably 0.01 to 1.0 mmol / l. The reaction pressure is usually 10 to 150 kg / m ² , and preferably 20 to 70 kg / m ² . A molecular weight modifier such as hydrogen may be present in the polymerization reaction system.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 The inside of a dried polymerization reactor equipped with a stirrer of Content 1 was sufficiently replaced with argon, and then dried with 400 ml of n-hexane.
-100 ml of octene was charged and the temperature was raised to 185 ° C.

Anisole 0.94 mmol / l, ethyl aluminum sesquichloride 1.9 mmol / l and dihexyl magnesium
After 0.47 mmol / l was added to the catalyst preparation device in this order and mixed, tetrabutoxytitanium 0.094 millicells / l was further added and mixed, and then ethylene gas was introduced into the above polymerization reactor at the same time, and the total pressure was increased. 190 ℃ while keeping at 40kg / cm ² G
Polymerization for 5 minutes at a density of 0.913 g / cm ² ethylene-1-
106.2 g of an octene copolymer was obtained.

Example 2 In place of anisole, 0.47 mmol / l of methyl t-butyl ether was added and copolymerization was carried out in the same manner as in Example 1,
Ethylene-1-octene copolymer 110 having a density of 0.914 g / cm ³ .
I got 9g.

Comparative Example 1 Polymerization was performed in the same manner as in Example 1 except that anisole was not added, and ethylene-1- having a density of 0.919 g / cm ^{3 was} added.
89.8 g of an octene copolymer was obtained.

It can be seen that when the ether compound is not added, the density of the polymer increases and the yield decreases.

Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1 except that the amount of 1-octene added was 150 ml, to obtain 82.9 g of a copolymer having a density of 0.913 g / cm ³ .

From this example, in order to obtain a copolymer having the same density as in Example 1 without adding an ether compound, the amount of 1-octene used was
It turns out that it needs to be multiplied by 1.5.

Example 3 The amount of methyl t-butyl ether added was 0.094 mmol / l.
Except that the copolymerization was carried out in the same manner as in Example 2 to obtain an ethylene-1-octene copolymer having a density of 0.915 g / cm ^3.
Obtained 113.3 g.

Example 4 Copolymerization was performed in the same manner as in Example 1 except that 0.47 mmol / l of methyl n-butyl ether was added instead of anisole, and an ethylene-1-octene copolymer having a density of 0.913 g / cm ³ was obtained. Obtained 115.7 g.

Example 5 Polymerization was carried out in the same manner as in Example 2 except that tetraisopropoxy titanium (0.094 mmol / l) was added in place of tetrabutoxy titanium (ethylene) having a density of 0.915 g / cm ³ .
105.8 g of 1-octene copolymer was obtained.

Table 1 shows the polymerization conditions and the polymerization results of Examples 1 to 5 and Comparative Examples 1 and 2 described above.

Example 6 In a catalyst supply line connected to the continuous polymerization reaction vessel of 1, dried n-hexane was added at 7.5 l / hr, ethylaluminum sesquichloride was 1.65 mmol / hr, dihexylmagnesium was 0.79 mmol / hr, and anisole was added.
After introducing at a rate of 0.83 mmol / hour and thoroughly mixing,
Further, tetrabutoxy titanium was introduced into the catalyst supply line at a rate of 0.17 mmol / hour. At the same time the polymerization reaction of ethylene 700 g / time into the container, hydrogen 0.02 g / time, the 1-octene was continuously fed at a rate of 600 g / time, average residence under the conditions of reaction temperature 185 ° C., a reaction pressure 70 kg / cm ² G Polymerization reaction was carried out for 0.11 hour to obtain 666 g of an ethylene-1-octene copolymer per hour.

Example 7 Example 1 was repeated except that methyl t-butyl ether was used instead of anisole in an amount of 0.41 mmol / hour.
649 g of ethylene-1-octene copolymer was obtained per hour.

Comparative Example 3 An ethylene-1-octene copolymer was obtained in an amount of 551 g per hour in exactly the same manner as in Example 6 except that the ether compound was not fed into the polymerization reactor.

Table 2 shows the polymerization conditions and the polymerization results of Examples 6 and 7 and Comparative Example 3.

[Effect of the Invention] According to the method of the present invention, various ethylene polymers can be efficiently produced. In particular, a linear low-density ethylene polymer can be efficiently produced at a high temperature with a small amount of comonomer used, and a high polymer yield can be achieved. Further, the catalyst used in the method of the present invention has a high activity, and it is not necessary to increase the addition amount for improving the activity, and the residual amount of the catalyst in the polymer can be remarkably reduced. Therefore, a high quality polymer (copolymer) can be obtained without performing deashing treatment.

[Brief description of drawings]

FIG. 1 is a flow chart illustrating the method of the present invention.

Claims (1)

[Claims] 1. When an ethylene-based polymer is produced by homopolymerizing ethylene or copolymerizing ethylene with another α-olefin in the reaction medium in the presence of a catalyst, (A) a general formula Ti (OR ¹ ) _n X ¹ _4-n [wherein, R ¹ is an alkyl group having 1 to 18 carbon atoms, 6 to 18 carbon atoms]
Represents a cycloalkyl group or an aryl group having 6 to 18 carbon atoms, and X ¹ represents a halogen atom. In addition, n is 0 ≦ n ≦ 4
Is a real number that satisfies. And a titanium compound represented by the formula (B) (a): MgR ² R ³ [wherein R ² is an alkyl group having 1 to 18 carbon atoms or 6 carbon atoms]
To 18 aryl groups, R ³ represents an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a halogen atom. ] An organomagnesium compound represented by the formula: (b) General formula R ⁴ _m AlX ² _3-m [wherein R ⁴ is an alkyl group having 1 to 20 carbon atoms, and 6 to 20 carbon atoms]
Represents an aryl group, an alkoxy group having 1 to 20 carbon atoms or an aryloxy group having 6 to 20 carbon atoms, and X ² represents a halogen atom. Further, m is a real number that satisfies 0 <m ≦ 3. When m is plural, each R ⁴ may be the same or different. The organic aluminum compound and (c) of the general formula R ⁵ OR ⁶ [wherein represented by], R ⁵ and R ⁶ represents an alkyl group or an aryl group having 6 to 18 carbon atoms having 1 to 18 carbon atoms. ] The method for producing an ethylene-based polymer, which comprises using a catalyst comprising a reaction product of an ether compound represented by: and carrying out polymerization or copolymerization under heating conditions in which the produced polymer is dissolved in the reaction medium.