JPH0125768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an ethylene copolymer. More specifically, the present invention relates to a method for producing an ethylene copolymer using a novel catalyst containing a magnesium compound and a titanium compound.

It is already known that catalyst systems containing magnesium compounds and titanium compounds can be used for the production of copolymers of ethylene and alpha-olefins. For example, as magnesium carriers, magnesium compounds such as magnesium oxide, magnesium hydroxychloride, magnesium hydroxide, magnesium alkoxide, magnesium dihalide. Furthermore, a catalyst system has been proposed that consists of a combination of these magnesium-containing compounds pretreated with compounds such as water, alcohols, aldehydes, ketones, esters, ethers, and carboxylic acids, and a titanium compound. ing.

However, these catalyst systems do not necessarily have sufficient polymerization activity, especially at high temperatures where the copolymer is dissolved.

Furthermore, the molecular weight distribution of the copolymer, which affects the physical properties of the product, is relatively wide, and therefore there is a relatively large amount of low molecular weight by-products called grease wax, which has the disadvantage of deteriorating productivity.

As a result of intensive studies, the present inventors used a specific compound as a titanium compound, prepared a homogeneous hydrocarbon solution containing a magnesium compound, a titanium compound, and an alcohol compound, and treated it with an organic aluminum halide compound. Polymerization activity can be increased by copolymerizing ethylene and α-olefin using a catalyst system consisting of the obtained hydrocarbon-insoluble solid in combination with an organoaluminum compound under conditions in which the polymer is dissolved in a hydrocarbon solvent. The present invention was accomplished by discovering that an ethylene copolymer with a density of 0.88 to 0.945 can be obtained, and the molecular weight distribution is narrower.

That is, the gist of the present invention is that the general formula Mg(OR ² ) _n
X ² _2-n (wherein R ² represents an alkyl, aryl or cycloalkyl group, X ² represents a halogen atom,
m is 1 or 2), a magnesium compound represented by the general formula Ti(OR ³ ) _o X ³ _4-o (wherein R ³ represents an alkyl, aryl or cycloalkyl group,
X ³ represents a halogen atom, n is 1, 2 or 3) and a titanium compound represented by the general formula,
A homogeneous hydrocarbon solution containing an alcohol compound represented by R ⁴ OH (wherein R ⁴ represents an alkyl, aryl or cycloalkyl group) is mixed with a homogeneous hydrocarbon solution containing the general formula Al ¹ _l
X ¹ _3-l (wherein R ¹ represents an alkyl, aryl or cycloalkyl group, X ¹ represents a halogen atom,
l represents a number of 1≦l≦2. ) in a hydrocarbon solvent in the presence of a catalyst system consisting of a combination of a hydrocarbon-insoluble solid obtained by treatment with an organoaluminium halide compound and an organoaluminum compound, under conditions in which the resulting polymer is dissolved. The present invention relates to a method for producing an ethylene copolymer, which comprises copolymerizing it with an α-olefin.

To further explain the present invention in detail, the magnesium compound has the general formula Mg(OR ² ) _n X ² _2-n (wherein R ²
represents an alkyl, aryl or cycloalkyl group, X ² represents a halogen atom, and m is 1 or 2. ) is used. Specifically, R ² is methyl, ethyl, propyl, butyl,
Compounds which are alkyl, aryl or cycloalkyl groups having up to about 15 carbon atoms such as pentyl, hexyl, octyl, phenyl, tolyl, xylyl, cyclohexyl, etc., and where X ² is chlorine, bromine or iodine, such as dimethoxymagnesium, diethoxy Examples include magnesium, ethoxymagnesium chloride, diphenoxymagnesium, and the like. Among these, compounds in which m in the general formula is 2 are preferred. Among them, diethoxymagnesium is most suitable.

On the other hand, titanium compounds have the general formula Ti(OR ³ ) _o
X ³ _4-o (wherein R ³ represents an alkyl, aryl or cycloalkyl group, X ³ represents a halogen atom,
n is 1, 2 or 3. ) is used. Examples of R ³ and X ³ include those exemplified above for R ² and X ^2. Specifically, examples of compounds where n is 2 include diethoxydichlorotitanium,
Examples of compounds where n is 3, such as di-n-propoxydichlorotitanium and di-n-butoxydichlorotitanium, include triethoxymonochlortitanium and tri-n
-Propoxymonochlortitanium, tri-n-butoxymonochlortitanium, etc.; Compounds where n is 1 include ethoxytrichlortitanium, n-propoxytrichlortitanium, and n-butoxytrichlortitanium. Among these, those where n is 3 or 2, particularly those where n is 3 are preferred. Among them, tri-n-butoxymonochlorotitanium is most suitable.

As the alcohol compound, a compound represented by the general formula R ⁴ OH (wherein R ⁴ represents an alkyl group, an aryl group, or a cycloalkyl group) is used. Examples of the above R ⁴ include those exemplified above for R ² . Specific examples include ethyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, and n-octyl alcohol. Among them, n-butyl alcohol is most preferred.

In the method of the present invention, first, a homogeneous hydrocarbon solution containing the above-mentioned magnesium compound, titanium compound, and alcohol compound is prepared. As the hydrocarbon used as a solvent, aliphatic hydrocarbons such as hexane and heptane, and alicyclic hydrocarbons such as cyclohexane can be used, but aromatic hydrocarbons such as benzene, toluene and xylene are particularly preferred.

To prepare a hydrocarbon solution, it is preferable to mix a magnesium compound, a titanium compound, and an alcohol compound in advance to prepare a homogeneous liquid. The order of mixing the three components is not particularly limited and may be arbitrary. After mixing, a uniform alcohol solution can be obtained by heating preferably to 100°C to 170°C.

A hydrocarbon solvent is then added to form a hydrocarbon solution, and the resulting hydrocarbon solution is treated with an organic aluminum halide compound without substantially removing the alcohol compound to obtain a hydrocarbon-insoluble solid.

As organic aluminum halide compounds,
Represented _by ^the general ^{formula AlR 1} _l compound is used.

Examples of R ¹ and X ¹ in the general formula include those exemplified above for R ² and X ² . Specific examples include methylaluminum dichloride, methylaluminum sesquichloride, dimethylaluminum monochloride, ethylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminum monochloride, isobutylaluminum dichloride, isobutylaluminum sesquichloride, diisobutylaluminum monochloride, and the like. Particularly preferred are ethylaluminum dichloride, ethylaluminum sesquichloride, and diethylaluminium monochloride, and among them, ethylaluminum sesquichloride and ethylaluminum dichloride give the most preferable results. The organic aluminum halide compound treatment can be carried out by adding the organic aluminum halide compound to a homogeneous hydrocarbon solution and allowing the reaction to occur preferably at a temperature of 20 to 100°C.
Since a hydrocarbon-insoluble solid is obtained, the solid can be separated and washed with a hydrocarbon solvent.

Therefore, regarding the amount of each component used, if the number of moles of magnesium compound, titanium compound, alcohol compound, and organic aluminum halide compound used is b, c, d, and a, respectively, m, n, Between l, 1≦
a×(3-l)×b+(2-m)+c×(4-n)/m
It is preferable to select a ratio that satisfies xb+nxc+d≦10.
When this value is less than 1, the polymerization activity decreases, and when it exceeds 10, the amount of organic aluminum halide used becomes too large. Also, within the above range, 1≦
When b/c≦4, especially 2≦b/c≦3, a catalyst with particularly high polymerization activity can be obtained.

Next, as an organoaluminum compound used as a cocatalyst, for example, the general formula AlR ⁵ _p X ⁵ _3-p (where R ⁵
represents an alkyl, aryl or cycloalkyl group, X ⁵ represents a halogen atom, and p represents a number from 1 to 3. ) can be mentioned.
Examples of R ⁵ and X ⁵ include those exemplified as R ² and X ² . Specific examples include trialkylaluminum such as triethylaluminum, tri-n-propylaluminum, triisobutylaluminum, diethylaluminum chloride, di-n-
- Dialkylaluminum chlorides such as propylaluminum chloride and diisobutylaluminum chloride; alkylaluminum sesquichlorides such as ethylaluminum sesquichloride, n-propylaluminum sesquichloride and isobutylaluminum sesquichloride; and mixtures thereof. Among these, compounds in which p in the general formula shown above is 1.5 or 2, especially dialkyl aluminum chloride and alkylaluminum sesquichloride, can be polymerized for a long time because their polymerization activity decreases little over time, and α can be copolymerized with ethylene. - It is preferable in that the copolymerization reactivity ratio of olefin is large.

Among these compounds, diethylaluminum chloride and ethylaluminum sesquichloride are particularly preferred.

The ratio of hydrocarbon-insoluble solids and organoaluminum compounds used is usually 0.1 to 100 in terms of Al/Ti atomic ratio.
Preferably, it is used within the range of 1 to 20. The thus prepared catalyst system is used to copolymerize ethylene and α-olefin, and the α-olefin used in the method of the present invention includes propylene, 1-butene, 1-pentene, 1-hexene,
There are α-olefins such as octene-1. Among these, α-olefins having 4 to 6 carbon atoms are preferable because they provide good productivity and physical properties of the copolymer.

In order to obtain an ethylene copolymer having a density of 0.88 to 0.945 by copolymerizing the α-olefin as described above, it is preferable that the α-olefin units contained in the ethylene copolymer be as follows.
That is, when α-olefin is propylene, 3 to 40
% by weight, 2-25% by weight for butene-1, 2-30% by weight for hexene-1, octene-1, etc.
shall be. Of course, a mixture of these α-olefins may also be used, but in that case it will be quite complicated, but the amount is generally 2 to 35% by weight.

The polymerization reaction is carried out using a solution polymerization method in a hydrocarbon solvent, and in the presence of a hydrocarbon solvent, the olefin or olefin mixture is supplied and maintained at a predetermined temperature and pressure at which the resulting copolymer dissolves. It is done. As the hydrocarbon solvent, inert solvents such as aliphatic hydrocarbons such as pentane, hexane, heptane, octane and isooctane, and aromatic hydrocarbons such as benzene and toluene are used. Polymerization reaction is usually carried out at 120°C to 250°C
temperature and pressure of 5 to 100 atmospheres.

Further, in the method of the present invention, when hydrogen is present in the polymerization reaction zone, the effect of controlling the molecular weight by hydrogen is large, and a polymer having a desired molecular weight can be easily obtained. The amount of hydrogen to be present varies depending on the polymerization conditions, the desired molecular weight of the olefin polymer, etc., and therefore it is necessary to adjust the amount of hydrogen introduced accordingly.

According to the method of the present invention as described above, the catalyst has very high activity, especially at high temperatures where the copolymer is dissolved, and therefore the step of removing catalyst residue in the copolymer can be omitted. This has great process advantages. Furthermore, the obtained copolymer has a very narrow molecular weight distribution, produces little by-product grease wax, and can achieve high productivity.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

The melt index in the examples is ASTM・D・
Measured at 190℃ and 2.16Kg load based on 1238・57T.
Expressed in MI. Furthermore, the flow rate ratio (hereinafter abbreviated as FR), which is a measure of molecular weight distribution, is a value that indicates the dependence of melt viscosity on shear stress, and is based on ASTM D 1238.
According to 57T, shear stress 10 ⁶ dyne/cm ² and 10 ⁵ dyne/cm 2
It is expressed as a ratio of melt indexes measured in cm ² , and it is said that the larger the FR, the broader the molecular weight distribution, and the smaller the FR, the narrower the molecular weight distribution. The density is
Measured at 20°C in accordance with ASTM D 1505.
The content of pendant ethyl groups was determined from the absorbance at 770 cm ^-1 by infrared absorption spectroscopy. Further, FIG. 1 is a flowchart diagram to help understand the technical content included in the present invention, and the present invention is not limited in any way by the flowchart diagram as long as it does not deviate from the gist thereof.

Example 1 (1) Catalyst preparation 20 mmol of magnesium diethylate, 10 mmol of tri-n-butoxymonochlorotitanium and 10 mmol of n-butanol were mixed and heated at 140°C.
The mixture was stirred for 4 hours to form a homogeneous solution. Then 60
The temperature was lowered to ℃ and 150 c.c. of benzene was added to make a homogeneous solution.

Next, 100 mmol of ethylaluminum sesquichloride was added dropwise over 20 minutes at 60℃, and then
The mixture was stirred at 60°C for 1 hour.

The generated precipitate was washed with normal hexane and dried to obtain a solid powder.

(2) Polymerization 2N-hexane 1000ml in autoclave
cc was taken and 5 mg of the above solid powder was charged. 150℃
After raising the temperature to
Ethylene was introduced along with 125g of butene and the total pressure
The weight was 11Kg/ ^cm2 . Ethylene absorption was observed as ethylene was introduced, but ethylene was additionally introduced to maintain the total pressure at 11 Kg/ ^cm2 , and after 1 hour, polymerization was stopped by injection of ethanol, resulting in MI = 1.7.
125 g of copolymer with FR=18 were obtained. This copolymer had 25 pendant ethyl groups per 1000 carbons and a density of 0.915 g/cm ³ .

Example 2 Polymerization was carried out under exactly the same conditions as in Example 1, except that 5 mg of the same solid powder as in Example 1 was used, the hydrogen/ethylene molar ratio in the gas phase was 0.03, and the amount of butene charged was 45 g. 100 g of copolymer with =3.1FR=18 were obtained. This copolymer is
It has 45 pendant ethyl groups per 1000 carbons,
The density was 0.892g/ ^cm3 .

Example 3 Polymerization was carried out under exactly the same conditions as in Example 1 except that 5 mg of the same solid powder as in Example 1 was used, the molar ratio of hydrogen/ethylene in the gas phase was changed to 0.11, and the cocatalyst was changed to 0.16 mmol of ethyl sesquichloride. As a result, 30 g of a copolymer having MI=2.5 and FR=18 was obtained. This copolymer had 31 pendant ethyl groups per 1000 carbons and a density of 0.911 g/cm ³ .

Example 4 Using 5 mg of the same solid powder as in Example 1, hydrogen was introduced so that the hydrogen/ethylene molar ratio in the gas phase was 0.13, and then triethylaluminum was added.
Polymerization was carried out under the same conditions as in Example 1 except that the amount was changed to 0.08 mmol, and 136 g of a copolymer having MI=4.3 and FR=19 was obtained. This copolymer is
It has 21 pendant ethyl groups per 1000 carbons,
The density was 0.920g/ ^cm3 .

Example 5 The same procedure as Example 1 was used except that 5 mg of the same solid powder as in Example 1 was used, the molar ratio of hydrogen/ethylene in the gas phase was 0.15, the cocatalyst was 0.08 mmol of triethylaluminum, and the polymerization time was 30 minutes. When polymerized under the same conditions, 120 g of a copolymer having MI=8 and FR=17 was obtained, the density was 0.920 g/cm ³ and the number of pendant ethyl groups was 21/1000 carbons.

Example 6 Polymerization was carried out in the same manner as in Example 5 except that the amount of butene charged was 50 g and the ratio of hydrogen to ethylene was 0.02, and 88 g of a copolymer was obtained. The copolymer has MI = 1.0, FR = 18, pendant ethyl groups = 40/1000 carbons, and density 0.890g/
It was warm at ^cm3 .

Example 7 (1) Catalyst Production A solid powder was produced in the same manner as in Example 1, except that 75 mmol of ethylaluminum dichloride was used instead of ethylaluminum sesquichloride.

(2) Polymerization Copolymerization was carried out under the same conditions as in Example 5, except that the above solid powder was used.
78g of copolymer was obtained. The copolymer has MI=
10, FR=19, pendant ethyl group=21 pieces/
It had 1000 carbon and a density of 0.921 g/cm ³ .

Example 8 (1) Catalyst Production A solid powder was produced in the same manner as in Example 1, except that 150 mmol of diethyl aluminum monochloride was used instead of ethyl aluminum sesquichloride.

(2) Polymerization Copolymerization was carried out under the same conditions as in Example 5, except that the above solid powder was used, and 90 g of a copolymer was obtained.

The copolymer has MI=5, FR=17, pendant ethyl groups=20/1000 carbons, and a density of 0.922 g/1000 carbons.
It was warm at ^cm3 .

[Brief explanation of drawings]

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

Claims (1)

[Claims] 1 General formula Mg(OR ² ) _n X ² _2-n (wherein R ² represents an alkyl, aryl or cycloalkyl group, and X ²
represents a halogen atom, m is 1 or 2), a magnesium compound represented by the general formula Ti
(OR ³ ) _o X ³ _4-o (wherein R ³ represents an alkyl, aryl or cycloalkyl group, X ³ represents a halogen atom, and n is 1, 2 or 3). and a homogeneous hydrocarbon solution containing an alcohol compound of the general formula R ⁴ OH (wherein R ⁴ represents an alkyl, aryl or cycloalkyl group), a homogeneous hydrocarbon solution containing an alcohol compound of the general formula AlR ¹ _l X ¹ _3-l (in the formula , R ¹ represents an alkyl, aryl or cycloalkyl group, X ¹ represents a halogen atom, and l represents a number of 1≦l≦2. An ethylene copolymerization process characterized in that ethylene and α-olefin are copolymerized in a hydrocarbon solvent in the presence of a catalyst system comprising a combination of a hydrogen-insoluble solid and an organoaluminum compound under conditions in which the resulting polymer is dissolved. Method for producing polymers. 2. The organoaluminum compound combined with the hydrocarbon-insoluble solid has the general formula AlR ⁵ _p X ⁵ _3-p , where R ⁵ represents an alkyl, aryl or cycloalkyl group;
The method for producing an ethylene copolymer according to claim 1, wherein X ⁵ is a halogen atom and p is a number from 1 to 3. 3. The method for producing an ethylene copolymer according to claim 1, wherein the organoaluminum compound to be combined with the hydrocarbon-insoluble solid is dialkyl aluminum chloride or alkyl aluminum sesquichloride.