JPH0737492B2 - Method for producing ethylene copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] This invention relates to ethylene and α-olefins having 5 to 6 carbon atoms, such as pentene-1, hexene-1 and α-olefins having 8 to 18 carbon atoms. For example, regarding a method for producing an ethylene copolymer with octene-1, etc., more specifically, a polymer excellent in mechanical properties, moldability, transparency,
The present invention relates to a method for producing an ethylene copolymer which can be produced in a high polymer yield in the presence of a catalyst having a high polymerization activity.

[Conventional technology and its problems]

Conventionally, as a method for producing an ethylene copolymer such as linear low density polyethylene (LLDPE), a method of performing high temperature solution polymerization in the presence of a catalyst obtained from an organomagnesium compound, a titanium compound and an organoaluminum compound (Japanese Patent Publication No. 60-11925, JP-A-60-42405, etc.) are known.

By the way, generally, in solution polymerization, since the produced polymer is dissolved in a solvent and the liquid viscosity in the polymerization system increases, it is desirable to perform the polymerization at a high temperature (155 ° C. or higher) from the viewpoint of the operation of the apparatus.

However, all of the catalysts used in the conventional known methods are
There is a problem that the activity at a temperature of 155 ° C. or higher is insufficient and the physical properties of the copolymer obtained by the conventional high temperature solution polymerization are not yet satisfactory.

[Object of the Invention]

 The present invention has been made based on the above circumstances.

That is, an object of the present invention is to provide a method for producing an ethylene copolymer which is excellent in various properties such as mechanical properties, moldability and transparency by increasing the catalytic activity.

[Means for achieving the above object]

In order to achieve the above-mentioned object, as a result of diligent research by the present inventor, a catalyst obtained by specifically selecting dialkylmagnesium among magnesium compounds and contacting and reacting it with an organoaluminum compound and a titanium compound in a specific order is Its activity is high, and when such a catalyst is used to copolymerize ethylene with an α-olefin having 5 to 6 carbon atoms and an α-olefin having 8 to 18 carbon atoms, the resulting copolymer has a film impact strength. The inventors arrived at the present invention by finding that they have excellent mechanical properties such as, moldability, and various properties such as transparency.

That is, the gist of the present invention for achieving the above object, the (1) dialkylmagnesium R ¹ R ² Mg ............... represented by formula (1) (in the equation (1), R ¹ , R ² each have 1 to 1 carbon atoms
18 alkyl and cycloalkyl groups are shown. ) And an organoaluminum compound, and a titanium compound Ti (OR ³ ) nX _4- n ………… (2) represented by the formula (2) (wherein R ³ in the formula (2) is Represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group, X represents a halogen atom, and n represents 0 ≦ n ≦
It is a real number that satisfies 4. In the presence of the catalyst obtained from), ethylene and a carbon number of 5 to 6 at a temperature of 155 ° C or higher.
The method for producing an ethylene copolymer is characterized by copolymerizing the above α-olefin with an α-olefin having 8 to 18 carbon atoms.

Specific examples of the dialkyl magnesium represented by the formula (1) include diethyl magnesium, dibutyl magnesium, butyl octyl magnesium, diamyl magnesium, dihexyl magnesium, dioctyl magnesium, ethyl butyl magnesium, and butyl isopropyl magnesium. Of these, dibutylmagnesium, dihexylmagnesium, butyloctylmagnesium and the like are preferable. Further, in the present invention, when a magnesium compound other than the dialkyl magnesium represented by the formula (1), such as magnesium chloride, is used, sufficient catalytic activity cannot be obtained.

There are various organoaluminum compounds, but usually at least one aluminum-
A compound having a carbon bond is used, and for example, a compound represented by the general formula R ⁴ ₃ A
l, R ⁴ ₂ AlX ² , R ⁴ AlX ² ₂ , R ⁴ ₂ AlOR ⁵ , R ⁴ Al (OR ⁵ ) X ² , R ⁴ ₃ A
l ₂ X ² ₃ (wherein R ⁴ and R ⁵ are each 1 to 20 carbon atoms)
Represents an alkyl group or an aryl group, and X ² represents a halogen atom. ). Suitable examples of the organic aluminum include diethyl aluminum monochloride, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride,
Dioctyl aluminum monochloride, ethyl aluminum dichloride, isopropyl aluminum dichloride, can be mentioned ethylaluminum sesquichloride, etc., R ⁴ among these ₃ e.g. ethylaluminum sesquichloride represented by Al ₂ X ² ₃ chloride and R ⁴ ₂ A
Preferred is, for example, diethyl aluminum monochloride represented by lX ² .

In the production method of the present invention, a reaction product of the dialkylmagnesium and the organoaluminum compound [hereinafter, this reaction product may be abbreviated as a component (A). ] And the titanium compound represented by the above formula (2) [hereinafter, this titanium compound may be abbreviated as component (B). ] The catalyst obtained from and is used.

The component (A) is limited by adding the dialkylmagnesium and the organoaluminum to an inert solvent and catalyzing the mixture at a temperature of, for example, -40 to 240 ° C.

Examples of the inert solvent include aliphatic hydrocarbons having 5 to 16 carbon atoms, alicyclic hydrocarbons, aromatic hydrocarbons, and the like. Specifically, normal- or iso-pentane,
Hexane, heptane, octane, nonane, decane, tetradecane, cyclohexane, benzene, toluene, xylene and the like can be mentioned. Further, as the inert solvent, the above-mentioned various hydrocarbons can be used alone. As a preferable inert solvent, for example, n-hexane can be mentioned.

Specific examples of the component (B) include tetramethoxy titanium, tetraethoxy titanium, tetra-n-propoxy titanium, tetraisopropoxy titanium, tetra-nm butoxy titanium, tetraisobutoxy titanium, tetracyclohexoxy titanium, and tetraphenoxy titanium. Such as the general formula Ti
Tetraalkoxy titanium represented by (OR ³ ) ₄ ; titanium tetrahalide represented by the general formula TiX ₄ such as TiCl ₄ , TiBr ₄ , TiI ₄ ; (CH ₃ O) TiCl ₃ , (C ₂ H ₅ O) TiCl _{3, (C 3 H 7 O} ) TiCl 3, (n-C 4 H 9) TiCl 3, (C 2 H 5) TiBr trihalide such as ₃ alkoxy _{titanium; (CH 3 O) TiCl 2} , (C 2 _{H 5 O) 2 TiCl 2,} (C 3 H 7 O) 2 TiCl 2, (n-C 4 H 9 O) 2, TiCl 2, (C 2 H 5 O) 2 dihalogenated titanium TiCl ₂ and the like; ( _{CH 3 O) 3 TiCl, (} C 2 H 5 O) 3 TiCl, (C 3 H 7 O) 3 TiCl, include _{(n-C 4 H 9 O} ) mono titanium halide such as ₃ TiCl.

Among these, tetraalkoxy titanium represented by the general formula Ti (OR ³ ) ₄ and titanium tetrahalide represented by TiX ₄ are 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.

The catalyst in the method of the present invention contains the above-mentioned components (A) and (B) as main components. That is, the reaction product (A) of the dialkyl magnesium and the organic aluminum compound and the titanium compound (B) are the main components. If the component (A) is not prepared in advance and the organoaluminum compound and the titanium compound are reacted with each other and then brought into contact with dialkylmagnesium, the activity of the resulting catalyst is not improved.

When the catalyst is prepared by mixing the components (A) and (B), the ratio of each metal in the catalyst is magnesium / titanium, atomic ratio) = 0.1 to 30, preferably 0.5 to 20, aluminum / It is desirable to adjust titanium (atomic ratio) = 1 to 120, preferably 5 to 80. If the atomic ratio of magnesium / titanium deviates from the above range, the catalytic activity may decrease. Further, when the atomic ratio of aluminum / titanium is less than 1, the activity of the catalyst is low, and conversely, when it exceeds 120, the improvement in activity corresponding to the added amount is not recognized. Further, when the amount is out of the above range, the physical properties of the obtained copolymer, particularly the film moldability, deteriorates.

According to the method of the present invention, ethylene and α having 5 to 6 carbon atoms are present in the presence of the catalyst and at a temperature of 155 ° C. or higher.
-The copolymerization of the olefin and the α-olefin having 8 to 18 carbon atoms proceeds.

Examples of the α-olefin having 5 to 6 carbon atoms include pentene-1, hexene-1, 3-methylpentene-1, and 4-methylpentene-1. 5 carbons in this invention
Any one or both of the .alpha.-olefins of .about.6 can be used at the same time.

Examples of the α-olefin having 8 to 18 carbon atoms include linear monoolefins such as octene-1, nonene-1, decene-1, undecene-1, and dodecene-1, 2-ethyl-hexene-1,2 , 2,4-Trimethyl-pentene-2
And branched olefins, and styrene and the like. Among these, the linear monoolefin is particularly preferable.

A suitable combination as a raw material monomer used in the reaction of the present invention is ethylene, hexene-1 and octene-1.

When ethylene is copolymerized with the α-olefin having 5 to 6 carbon atoms and the α-olefin having 8 to 18 carbon atoms, the linear low-density polyethylene obtained has an ethylene unit content of 90 to 99.2 mol%. The raw material monomer mixture is supplied so that the unit content of the α-olefin having 5 to 6 carbon atoms is 0.4 to 9.6 mol% and the unit content of the α-olefin having 8 to 18 carbon atoms is 0.4 to 9.6 mol%. Then, the density 0.910 to 0.940 g / cm
³ Especially 0.910 to 0.936g / cm ³ , Melt index (MI) 0.1 to 10g / 10
A linear low-density polyethylene having a melting flow ratio (MFR = flow rate / melting index) of 18 to 52, particularly 23 to 48, can be suitably produced. When the ethylene copolymer has an MI of less than 0.1 g / 10 minutes or an MFR of less than 18, the moldability may deteriorate. Also
When the MI is larger than 10 g / 10 minutes or the MFR is larger than 52, the film impact strength and the transparency may be deteriorated.

The polymerization conditions in the present invention cannot be generally specified depending on the physical properties of the desired polymer, the type of the monomer, etc., but usually the catalyst concentration is 0.001 to 10 mmol / titanium concentration, preferably 0.01 to 1.0 mmol / titanium concentration. is there.
The reaction temperature is 155 ° C. or higher, particularly 160 to 220 ° C., that is, the temperature at which the liquid viscosity of the produced polymer solution is lowered is preferable for operating the apparatus, and the reaction pressure is 10 to 150 Kg / m ² G, particularly 20 to 70 Kg /
m ² G. Further, this polymerization reaction may be carried out in the presence or absence of an inert solvent. Further, a molecular weight modifier such as hydrogen may be present in the polymerization reaction system. In addition,
Examples of the inert solvent include the above-mentioned aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbons.

〔The invention's effect〕

According to the method of the present invention, since (1) a catalyst obtained by contacting and reacting a dialkylmagnesium, an organoaluminum compound and a titanium compound in a specific order is used, the catalytic activity at a temperature of 155 ° C. or higher is used. Is high, and as a result, the polymer yield can be increased, and (2) the liquid viscosity of the produced polymer solution can be reduced, which is preferable for the operation of the apparatus, and (3) the obtained copolymer It is possible to provide a method for producing an ethylene copolymer, which has various excellent advantages such that the coalescence is excellent in various properties such as mechanical properties such as film impact strength, moldability, and transparency.

〔Example〕

Next, the present invention will be described more specifically by showing Examples and Comparative Examples of the present invention.

(Examples 1 to 8) Dehydrated n-hexane was added to 7.5 in the continuous polymerization vessel of 1.
/ Hour, 0.25 mmol / hour of titanium compound, dialkylmagnesium and organoaluminum compound were supplied at the rates shown in Table 1 and as shown in FIG. At the same time, ethylene 1300 g / hr, hydrogen 0.15 g / hr, comonomer first
Continuously supplied at the ratio shown in the table, reaction temperature 175 ℃, reaction pressure 7
Polymerization reaction was carried out for 0.11 hours under conditions of 0 Kg / m ² G to obtain an ethylene copolymer. The results are shown in Table 1.

(Comparative Example 1) The procedure of Example 3 was repeated, except that each component was separately supplied to the polymerization vessel. The results are shown in Table 1.

Comparative Example 2 The procedure of Example 3 was repeated, except that the titanium compound and the organoaluminum compound were reacted and then contacted with dialkylmagnesium. The results are shown in Table 1.

(Comparative Example 3) The procedure of Example 4 was repeated, except that each component was separately fed to the polymerization vessel. The results are shown in Table 1.

(Comparative Example 4) 10 mol of anhydrous magnesium chloride was suspended in dehydrated n-hexane 30 in a nitrogen stream, 60 mol of ethanol was added dropwise with stirring, and the mixture was reacted at 30 ° C for 1 hour. Then, 27 mol of diethylaluminum chloride was added dropwise to this and stirred,
30 mol of titanium tetrachloride was added and reacted at 80 ° C. for 3 hours to obtain a solid catalyst component.

The obtained solid catalyst component was supplied at 0.25 mmol / hour in terms of titanium and 16 mmol / hour of diethylaluminum chloride. At the same time, ethylene 1300g / hour, hydrogen 0.15g /
The comonomers were continuously supplied for a period of time at the ratio shown in Table 1, and the polymerization reaction was carried out for 0.11 hours under the conditions of a reaction temperature of 175 ° C. and a reaction pressure of 70 Kg / m ² G to obtain an ethylene copolymer. The results are shown in Table 1.

[Brief description of drawings]

FIG. 1 is a flow chart showing the catalyst preparation procedure in the method of the present invention.

Claims (1)

[Claims] 1. A dialkylmagnesium represented by the formula (1) R ¹ R ² Mg (1) (wherein R ¹ and R ^{2 in the} formula (1) each have 1 to 1 carbon atoms).
18 alkyl and cycloalkyl groups are shown. ) And an organoaluminum compound, and a titanium compound Ti (OR ³ ) nX _4- n ………… (2) represented by the formula (2) (wherein R ³ in the formula (2) is Represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group, X represents a halogen atom, and n represents 0 ≦ n ≦
It is a real number that satisfies 4. In the presence of the catalyst obtained from), ethylene and a carbon number of 5 to 6 at a temperature of 155 ° C or higher.
And an α-olefin having 8 to 18 carbon atoms are copolymerized with each other to produce an ethylene copolymer.