JPH0321605A - Production of polyolefin - Google Patents

Abstract

PURPOSE:To obtain the subject polymer having narrow mol.wt. distribution, good strength and good dimensional stability and free from fish eyes by polymerizing ethylene or a mixture thereof with an alpha-olefin in the presence of a catalyst containing a specific hydrocarbon-insoluble solid, an organic Al compound and an oxygen-containing compound under such a condition that the resultant polymer is dissolved in a solvent. CONSTITUTION:Ethylene or a mixture thereof with an alpha-olefin is polymerized in the presence of a catalyst comprising a combination of (A) a hydrocarbon- insoluble solid, (B) an organic Al compound and (C) an oxygen-containing compound of formula IV (R<6> and R<7> are alkyl, aryl, etc.) or formula V (R<8> and R<9> are alkyl, aryl, etc.) in an inert solvent under such a condition that the prepared polymer is dissolved in the solvent, the hydrocarbon-insoluble solid A being prepared by treating a hydrocarbon solution containing a Mg compound of formula I (R<2> is alkyl, aryl, etc.; X<2> is halogen; m is 1 or 2), a Ti compound of formula II (R<3> is alkyl, aryl, etc.; X<3> is halogen; n is 1 or 2) and if necessary a hydroxy compound of formula: R<4>OH (R<4> is alkyl, etc.) with a halogenated Si compound of formula III (R<1> is H, alkyl, etc.; X<1> is halogen; 0<=l<=2).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polyolefins. More specifically, using a specific catalyst containing a magnesium compound and a titanium compound, ethylene or ethylene and an α-olefin are reacted under conditions such that the formed polymer is dissolved in an inert solvent which forms a liquid phase under reaction conditions. polymerize the mixture with
The present invention relates to a method for producing a polyolefin with a narrow molecular weight distribution.

[Conventional technology]

In general, olefin polymerization methods include slurry polymerization, in which a polymer formed in an inert solvent that becomes a liquid phase under reaction conditions is suspended as a solid in the solvent; There is a so-called solution polymerization method in which polymerization is carried out under gas phase conditions, and a gas phase polymerization method in which polymerization is carried out under gas phase conditions. Each has its advantages and disadvantages, but compared to slurry polymerization, solution polymerization has the characteristics of superior uniformity of the resulting polymer and narrow molecular weight distribution and composition distribution.
Suitable for producing medium to low density ethylene copolymers.

In general, the narrower the molecular weight distribution of polyolefin, the better its mechanical properties, dimensional stability, etc. Furthermore, when a low-density copolymer is used as a modifier for other resins, it is necessary to have a particularly narrow molecular weight distribution, such as to reduce the occurrence of so-called fish eyes when forming Finolem.

It is known that catalyst systems containing magnesium and titanium compounds can be used for the polymerization of olefins. For example, JP-A Sho&/-3'Igg9 uses a catalyst system in which magnesium diethylate, titanium tetrabutyrate, and ethylaluminum dichloride are reacted;
In 2003, a catalyst system was proposed in which a hydrocarbon-insoluble solid obtained from the reaction of magnesium diethylate and a titanium compound containing a nitrogen compound was treated with an acid nitrogen compound. When olefins were polymerized using these catalyst systems, the molecular weight distribution of the resulting polyolefins was somewhat narrow.

As catalysts with narrow molecular weight distribution, homogeneous catalysts such as catalyst systems consisting of organic solvent-soluble vanadium compounds such as VC14, VOCl3, and (acetylacetone) and organic aluminum are known, but they generally have low polymerization activity;
A catalyst removal step is required.

[Problem that the invention seeks to solve]

Based on these facts, the present inventors have made extensive studies on a method for efficiently producing a polyolefin with a narrow molecular weight distribution and excellent copolymerizability and uniformity.

[Means for solving problems]

As a result, polyolefins with an extremely narrow molecular weight distribution can be obtained by polymerizing ethylene or a mixture of ethylene and α-olefin under specific conditions using a specific catalyst system that combines a magnesium compound and a titanium compound. They discovered this and arrived at the present invention.

That is, the gist of the present invention is that the general formula MIOZ(OR2
) mX2-m (wherein R2 represents an alkyl, aryl or cycloalkyl group, X2 represents a norogen atom,
m is l or y) and the general formula Ti (OR3)n
represents a halogen atom, n is /, 2 or 3) and in some cases, a titanium compound represented by the general formula R4
A homogeneous hydrocarbon solution containing a hydroxy compound represented by the formula R%SiX: 6 (wherein R+ is a hydrogen atom, alkyl, aryl) or represents a cycloalkyl group, XI represents a halogen atom, and l represents O≦j
Production of a polyolefin characterized by combining a hydrocarbon-insoluble solid obtained by treatment with a halogenated silicon compound represented by ≦2 and an organoaluminum compound and polymerizing an olefin using a catalyst system according to t. It lies in the method.

To further explain the present invention in detail, the magnesium compound has the general formula Mg (OR2)m X: - m (
In the formula, R2 represents an alkyl, aryl or cycloalkyl group, X2 represents a halogen atom, and m is/or 2.

Specifically, R2 is methyl, ethyl, proyl, butyl,
Pentyl, hexyl, octyl, phenyl, tolyl, xylyl, cyclohexyl, etc., are alkyl, aryl, and cycloalkyl groups up to the carbon number/S, and compounds in which X2 is chlorine, bromine, or iodine, such as dimethoxymagnesium, dimethoxymagnesium, Examples include ethoxymagnesium, 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, as a titanium compound, the general formula Ti(OR3)nX:
,, -n (wherein R3 represents an alkyl, aryl or cycloalkyl group, X3 represents a halogen atom, and n represents l
, λ or 3) is used.

As R3, Dichlorotitanium, etc.; Compounds where n is 3 include triethoxymonochlortitanium, tri-n-propoxymonochlortitanium, tri-n-propoxymonochlortitanium, etc.; compounds where n is / include ethoxytrichlortitanium. , n-propoxytrichlortitanium, and n-butoxytrichlortitanium.

Among these, those where n is 3 or λ, particularly those where n is 3 are preferred. Among them, tri-n-butoxymonochlorotitanium is most suitable.

As the hydroxy compound, a compound represented by the general formula R40H (wherein R4 represents an alkyl group, an aryl group, or a cycloalkyl group) is used. Examples of the above R4 include those exemplified above for R2. Specific examples include ethyl alcohol, n-propyl alcohol, impropyl alcohol, n-butyl alcohol, isobutyl alcohol, n-bentyl alcohol, n-octyl alcohol, and cyclohexanol.

In the method of the present invention, first a homogeneous hydrocarbon solution containing the above-mentioned magnesium compound, titanium compound, and optionally a hydroxy compound is prepared. Examples of the hydrocarbon used as a solvent include aliphatic hydrocarbons such as hexane and hebutane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene. In order to prepare a hydrocarbon solution, it is preferable to mix a magnesium compound, a titanium compound, and in some cases a hydroxy 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, the mixture is preferably heated to io0°C to 70°C to obtain a uniform liquid or a uniform solution of the hydroxy compound.

Next, a hydrocarbon solvent is added to obtain a hydrocarbon solution, and when a hydroxy compound is added to the obtained hydrocarbon solution, the hydroxy compound may be removed, but usually the hydroxy compound is not substantially removed. Treatment with a halogenated silicon compound yields a hydrocarbon-insoluble solid.

As the halogenated silicon compound, general formula RpiSiX:
A compound represented by -l (wherein R1 represents a hydrogen atom, alkyl, aryl or cycloalkyl group, and l represents a number of O≦l≦2) is used. As R1 in the general formula, in addition to those exemplified above for R2, a hydrogen atom is
Examples of this include those exemplified above for X2.

Among these, compounds in which XI is a chlorine atom are preferred. Specific examples include silicon tetrachloride, methyltrichlorosilane, ethyltrichlorosilane, probyltrichlorosilane, butyltrichlorosilane, phenyltrichlorosilane, diethyldichlorosilane, trichlorosilane, methyldichlorosilane, ethyldichlorosilane, and the like.

Among them, the use of silicon tetrachloride and trichlorosilane gives preferable results.

Halogenated silicon compound treatment produces a homogeneous hydrocarbon solution.
Add a halogenated silicon compound, preferably 20 to 2
It is sufficient to carry out the reaction at a temperature of 00°C, and since a hydrocarbon-insoluble solid is obtained, the solid may be separated and washed with a hydrocarbon solvent.

Therefore, the amount of each portion can be arbitrarily selected as appropriate, but
Preferably, when the amounts of a magnesium compound, a titanium compound, and in some cases a hydroxy compound and a halogenated silicon compound during treatment with a silicon halide compound are respectively b, c, d, and a, m, n in the general formula
, l is selected at a ratio that satisfies the relationship between .

Next, as the organoaluminum compound used as a cocatalyst, for example, the general formula AArR'pXs p (wherein R
5 represents an alkyl, aryl or cycloalkyl group,
X5 represents a halogen atom, p represents a number from 7 to 3). R5, X5 is R
2. Examples include those exemplified as X2. Specifically, trialkylaluminum such as triethylaluminum, tri-n-probylaluminum, triisobutylaluminum, and dialkylaluminum oxides such as diethylaluminum chloride, di-n-probylaluminum chloride, diisobutylaluminum chloride, diethylaluminium bromide, etc. preferable. The ratio of the hydrocarbon-insoluble solid to the organoaluminum compound used is usually 0.00% in terms of the atomic ratio of All/Ti.
/~ioo, preferably /~20. As an oxygen-containing compound, the general formula R6-0-R7 (
R6 and R7 represent an alkyl, aryl, or cycloalkyl group), or R8-COOR9 (R
8 and R9 each represent an alkyl, aryl, cycloalkyl or alkenyl group). Specifically, diethyl ether,
Diprobyl ether, di-normal butyl ether, alkyl ether of n-butyl ethyl ether, aryl ethers such as anisole, phenethyl, benzyl ethyl ether, aromatic esters such as methyl benzoate, ethyl benzoate, ethyl para-methylbenzoate, butyl para-methylbenzoate, α, β monounsaturated esters such as methyl methacrylate, butyl methacrylate, isobutyl methacrylate, ethyl acrylate, methyl acetate, ethyl acetate, butyl acetate, ethyl formate, ethyl propionate, ethyl malonate natonoalkyl ester, etc. preferable. The ratio of the third component to the hydrocarbon-insoluble solid is usually 0.00% to Ti. /~/θO molar ratio, preferably 0. It is used in a molar ratio of 0 to 0. The catalyst system thus prepared is used to carry out the polymerization of ethylene or mixtures of ethylene and other alpha-olefins, other alpha-olefins used in the process of the invention include propylene, butene/, Examples include pentene/, octene/, and the like. Among them, the method of the present invention uses 3S mol%
It is advantageous for the production of copolymers of ethylene containing other alpha-olefins up to. The polymerization reaction is carried out by solution polymerization, which is carried out under conditions such that the polymer formed in an inert solvent is dissolved in the medium. Usually at a given temperature while feeding the olefin or olefin mixture in the presence of an inert solvent.
This is done by holding it under pressure. As the inert solvent, aliphatic hydrocarbons such as benzene, hexane, hebutane, octane, and inoctane, and aromatic hydrocarbons such as benzene and toluene are used. The polymerization reaction is usually carried out using I
Oθ~2! The temperature is selected from the range of 0°C, especially from /20 to 200°C and the pressure from the vapor pressure of the solvent to /00 atm.

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 that should 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.

〔Effect of the invention〕

The molecular weight distribution of the polyolefin produced by using the catalyst system obtained by the method of the present invention as described above is extremely narrow. That is, a polyolefin having a PR value of /S or less, which will be described later, can be easily obtained. Therefore, this polyolefin not only has excellent mechanical properties and dimensional stability, but also has a low amount of grease wax by-product during polyolefin production, and is less likely to contain hydrocarbons among the reaction products of magnesium compounds and titanium compounds. Since it is obtained using only a certain amount of soluble material, the polymer produced by the method of the present invention has the characteristic that it is extremely difficult for fisheye to grow.

〔Example〕

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.

In the examples, the polymerization activity K of the catalyst is K=C9 polymer)/
(.!i'-catalyst) (hr) ('K9/art2
(olefin pressure). Furthermore, the melt index is measured at iqo°C based on ASTM-D/23g-37T. 2. /A It was measured using a kg load and expressed as 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・/:l3g-! ;'According to IT, shear stress/o6
dyne/cyri2 and/o5dyne/cr
It is expressed as the ratio of melt indenoxes measured at rt2, and F. If R is a dog, the molecular weight distribution is wide;
If it is small, it is considered narrow.

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 unless it deviates from the gist thereof.

Example l. ．． 2 Magnesium diethyl}. 2 b mmol and a predetermined amount of tri-n-butoxymonochlorotitanium,
The mixture was stirred for q hours at /g θ°C to obtain a homogeneous red liquid. Then gθ
After cooling to ℃, a predetermined amount of benzene was added to make a homogeneous solution.

A predetermined amount of silicon tetrachloride was added here at θ℃, and then S
The mixture was stirred at a temperature of θ°C for 3 hours to ripen. The resulting precipitate was washed with n-hexane and subjected to polymerization in the form of n-hexane slurry.

Next, take normal hexane/l in a 2l autoclave, and add 0.32 ml of diethylaluminum monochloride.
Predetermined amounts of mmol and ethyl benzoate were charged. /lI
After raising the temperature to 15°C, hydrogen was introduced so that the molar ratio of hydrogen/ethylene in the gas phase became a predetermined value, and 20 m9 of the above solid powder was introduced together with ethylene and ptenol as a n-hexane slurry, and the total pressure was raised to 73 kg/l. The pressure was set to crIL2 (gauge pressure). As the olefin is introduced, absorption of olefin and temperature rise are observed, but additional olefin is introduced so that the total pressure becomes /Jk9/α2 and the molar ratio of putene//ethylene in the gas phase becomes a predetermined value. was maintained at 30°C. After 30 minutes, the polymerization was stopped by injection of ethanol. The results obtained are shown in Table 1.

Example 3 Polymerization was carried out in exactly the same manner as in Example 1, except that methyl methacrylate was used instead of ethyl benzoate. The results are shown in Table/.

Example G In the polymerization of Example 1, the polymerization was carried out in the same manner as in Example 1, except that hexene/ was used instead of mixing butene/. The results are shown in Table/.

Example! 24 mmol of magnesium diethylate, 3 mmol of triptoxymonochlorotitanium, and 3 mmol of normal putanol were mixed and stirred at /'70°C for q hours to obtain a homogeneous liquid. Next, after cooling to 60° C., normal hexane AOme was added to form a homogeneous solution.

20 b mmol of silicon tetrachloride was added thereto at po°C, and the mixture was stirred at SO°C for 3 hours. The resulting precipitate was washed with n-hexane and subjected to polymerization in the form of n-hexane slurry.

Next, polymerization was carried out in exactly the same manner as in the example except that n-butyl ether was used in place of the solid catalyst component and ethyl benzoate.

The results obtained are shown in Table 1.

Comparative Example/Normal hexane/l was placed in a 2l autoclave, and diethylaluminum chloride 0. ? jm m
o l and 3.4 μmol of methyl methacrylate were charged. After raising the temperature to qO°C, the hydrogen was heated to a temperature where the molar ratio of hydrogen/ethylene in the gas phase was 0. 20 m9 of the solid catalyst of Example/ was introduced together with ethylene and butene/,
Full pressure! It was set as rKG.

As the olefin is introduced, olefin absorption and temperature increase are observed, but the total pressure is gKG, and the ptene in the gas phase is
The molar ratio of ethylene is 0, . ．． ? Olefin was additionally introduced so as to increase the temperature, and 30 minutes later, the polymerization was stopped by pressurizing ethanol. The results obtained are shown in Table/. In this way, it can be seen that in slurry polymerization, the molecular weight distribution is wider than in solution polymerization even if the third command is present.

Comparative Example λ This was carried out in the same manner as in Example 1 except that ethyl benzoate was not added at all. The results are shown in Table/.

Comparative Example 3 Silicon tetrachloride. Ethylaluminum sesquichlorad/0.0 A mmol instead of 20 A mmol. 7 mmol slowly. ? Polymerization was carried out in the same manner as in Example S, except that the mixture was added dropwise over an hour and then stirred at AO°C for an hour to complete the polymerization. The results are shown in Table/.

Compared to Example S, the FR was 20, indicating a wide molecular weight distribution.

Group

[Brief explanation of drawings]

FIG. 1 is a flowchart showing one embodiment of the catalyst preparation process and polymerization process used in the present invention.

Claims (3)

[Claims] (1) (A) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
(In the formula, R^2 represents an alkyl, aryl, or cycloalkyl group, X^2 represents a halogen atom, and m is 1 or 2.) General formula ▲ Numerical formula, chemical formula, table, etc. There is ▼ (in the formula, R^
3 represents an alkyl, aryl or cycloalkyl group, X^3 represents a halogen atom, and n is 1, 2 or 3) and, in some cases, a titanium compound represented by the general formula R^4O
A homogeneous hydrocarbon solution containing a hydroxy compound represented by H (in the formula, R ^
1 represents a hydrogen atom, alkyl, aryl or cycloalkyl group, and X^
1 indicates a halogen atom, l indicates a number of 0≦l≦2)
A hydrocarbon-insoluble solid obtained by treatment with a halogenated silicon compound represented by (B) an organoaluminum compound and (C) a general formula R^6-O-R^7 (R^6 and R^7 are alkyl, aryl or cycloalkyl group) or R^8-COOR^9 (R^8 and R^
9 represents an alkyl, cycloalkyl, aryl, or alkenyl group) in an inert solvent that becomes a liquid phase under reaction conditions, and the polymer formed in the medium A method for producing polyolefin, which comprises polymerizing ethylene or a mixture of ethylene and α-olefin under conditions in which it dissolves in (2) The method for producing a polyolefin according to claim 1, wherein the oxygen-containing compound is ethyl methacrylate. (3) The method for producing a polyolefin according to any one of claims 1 to 2, wherein the density of the obtained polymer is 0.85 g/cc to 0.94 g/cc.