JPH0747604B2 - Method for producing polyolefin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyolefin by polymerizing an olefin, and more specifically, a moldability having a high stereoregulatory property and a broad molecular weight distribution. To provide an improved polyolefin of

(Prior Art and Problems to be Solved by the Invention) Ziegler type catalysts are well known as olefin polymerization catalysts, and methods for improving their activity and stereoregularity have been proposed. Above all, the improvement in activity has been greatly improved by using titanium, magnesium, and halogen as essential components as titanium components. However, when propylene or the like is polymerized using this catalyst, it is known that the practical value is lost because the resulting polymer has extremely low stereoregularity although the activity is very high. Generally, the rigidity and strength of a molded product strongly depend on the crystallinity of the polymer, and at the same time, the solid crystallinity is determined by the stereoregularity of the polymer. Therefore, higher rigidity,
In order to obtain a molded product having high strength, polypropylene having higher crystallinity has been desired. Therefore, various ester ethers are added to titanium components containing titanium, magnesium, and halogen.
A method for improving stereoregularity by incorporating an electron donor such as an amine has been proposed. On the other hand, there has been proposed a method of adding an ester, an ether, an amine, an organic silicon compound or the like in the polymerization of the titanium component and the organic aluminum. Such methods have significantly improved the stereoregularity of polymers. However, polyolefins obtained by polymerizing olefins using these catalyst systems generally have a narrow molecular weight distribution and are inferior in fluidity at the time of melting and lose flow orientation, so that the orientation strength of a molded article is significantly reduced. As a result, injection-molded products generally have problems such as a decrease in rigidity and a film having a weak rigidity.

(Means for Solving the Problems) The inventors of the present invention have made earnest studies on imparting high stereoregularity and a broad molecular weight distribution to polyolefins with respect to the above problems. As a result, titanium obtained by prepolymerization of olefins has been obtained. The present invention has been completed by finding that the intended purpose can be achieved by simultaneously using a specific organosilicon compound and ethyl silicate during the main polymerization using the contained polyolefin.

That is, the present invention includes: A A titanium-containing polyolefin obtained by prepolymerization B Organic aluminum compound C General formula [I] The method for producing a polyolefin is characterized by polymerizing an olefin in the presence of an organosilicon compound D ethyl silicate.

In the present invention, prepolymerization prior to the main polymerization of olefin is important for obtaining a polyolefin having a broad molecular weight distribution and high stereoregularity. As the prepolymerization, known methods can be adopted without any limitation. For example, a method of prepolymerizing an olefin in the presence of a titanium compound and an organoaluminum compound is general.

As the titanium compound used in the prepolymerization, compounds known to be used in the polymerization of propylene are adopted without any limitation. Particularly, a titanium compound containing titanium, magnesium and halogen as components and having high catalytic activity is preferable. Such a titanium compound having a high catalytic activity is one in which various halogen compounds, particularly titanium tetrachloride, are supported on various magnesium compounds.

As a method for producing this catalyst, a known method is adopted without any limitation. For example, JP-A-56-155206, JP-A-56-136806,
57-34103, 58-8706, 58-83006, 58-138708, 58
58-183709, 59-206408, 59-219311, 60-81208,
60-81209, 60-186508, 60-192708, 61-21130
9, Same 61-271304, Same 62-15209, Same 62-11706, Same 62-7270
2, the method disclosed in the same 62-104841 can be adopted. Specifically, for example, a method in which titanium tetrachloride is co-ground with a magnesium compound such as magnesium chloride, a titanium halide and a magnesium compound in the presence of an electron donor such as alcohol, ether, ester, ketone or aldehyde. Examples thereof include a method of co-milling or a method of bringing a titanium halide, a magnesium compound and an electron donor into contact with each other in a solvent.

Next, as the organoaluminum compound, a compound known to be used for the polymerization of propylene is adopted without any limitation. For example, trialkyl aluminums such as trimethyl aluminum, triethyl aluminum, tri-n propyl aluminum, tri-n butyl aluminum, tri-i butyl aluminum, tri-n hexyl aluminum, tri-n octyl aluminum, and tri-n decyl aluminum; Examples include diethyl aluminum monohalides such as diethyl aluminum monochloride; alkyl aluminum halides such as methyl aluminum sesquichloride, ethyl aluminum sesquichloride and ethyl aluminum dichloride. Alternatively, alkoxyaluminums such as monoethoxydiethylaluminum and diethoxymonoethylaluminum can be used. Of these, triethylaluminum is most preferable. The amount of the organic aluminum compound used is 1 to 100, preferably 2 to 20 in terms of Al / Ti (molar ratio) with respect to Ti atoms in the titanium compound.

In the prepolymerization of the present invention, the titanium compound described above,
In addition to the organoaluminum compound, the following general formula [II] R ″ -I [II] [wherein R ″ is an iodine atom or a hydrocarbon group. ] It is preferable to use the iodine compound represented by the following, because the crystallinity of the obtained polyolefin becomes higher.

In the general formula [II], R ″ is a hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, or an aryl group. Specific examples of iodine compounds that can be preferably used in the present invention are as follows. For example, iodine, methyl iodide, ethyl iodide, propyl iodide, butyl iodide, iodobenzene, toluene p-iodide, etc. Among them, methyl iodide and ethyl iodide are preferable. Is 0.1 to 100, preferably 0.5 to 50 in terms of I / Ti (molar ratio) with respect to the titanium atom in the titanium compound.

The olefins used in the prepolymerization include ethylene, propylene, 1-butene, 1-pentene, 1-hexene,
4-methylpentene-1 and the like can be mentioned. Further, although it is possible to use two or more kinds of the above olefins at the same time, it is preferable to use one kind of olefin in an amount of 90 mol% or more in consideration of improvement of stereoregularity. It is also possible to make hydrogen coexist in the prepolymerization. The amount of polymerization in the prepolymerization is preferably 1 to 100 g per 1 g of the titanium compound, and industrially the range of 2 to 50 g is suitable.

Preliminary polymerization is usually preferably applied by slurry polymerization, and as a solvent, hexane, heptane, cyclohexane, benzene, or a saturated aliphatic hydrocarbon or aromatic hydrocarbon such as toluene alone, or a mixed solvent thereof is used. it can. The prepolymerization temperature is −20 to 100.
C., especially 0 to 60.degree. C. are preferred. The prepolymerization time is
It may be appropriately determined according to the prepolymerization temperature and the polymerization amount in the prepolymerization, and the pressure in the prepolymerization is not limited, but in the case of slurry polymerization, it is generally atmospheric pressure to 5 k.
It is about g / cm ² . An electron donor such as ether, amine, amide, nitrile, carboxylic acid, sulfur-containing compound, acid amide, acid ester, acid anhydride, or organic silicon compound may be allowed to coexist during the prepolymerization. After the completion of prepolymerization, hexane, heptane, cyclohexane, benzene,
It is preferable to wash with saturated aliphatic hydrocarbon or aromatic hydrocarbon such as toluene alone or with a mixed solvent thereof, and the washing frequency is usually preferably 5 to 6 times.

After the preliminary polymerization, main polymerization is carried out. The main polymerization is carried out in the presence of the titanium-containing polyolefin obtained by the above prepolymerization, the organoaluminum compound, the organosilicon compound and ethyl silicate.

As the organoaluminum compound used in the main polymerization, those used in the above-mentioned prepolymerization can be used, and triethylaluminum is most preferable. The amount of the organoaluminum compound used is 10 to 1000, preferably 50 to 5 in terms of Al / Ti (molar ratio) with respect to the titanium atom in the titanium-containing polyolefin.
00.

Further, as the organosilicon compound, the compound represented by the above general formula [I] is adopted without any limitation. R and R'in the general formula [I] are hydrocarbon groups such as an alkyl group, an alkenyl group, an alkynyl group and an aryl group. Examples of the organosilicon compound preferably used in the present invention include:
It is as follows.

For example, trimethylmethoxysilane, trimethylethoxysilane, dimethylmethoxysilane, dimethylethoxysilane, diphenyldimethoxysilane, methylphenyldimethoxysilane, diphenyldiethoxysilane, ethyltrimethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxy. Silane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, cyclohexylmethyldimethoxysilane, butyltriethoxysilane, phenyltriethoxysilane, 6-triethoxysilyl2-
Norbornene and the like.

The amount of the organic silicon compound used in the polymerization is 0.1 to 0.1 in terms of Si / Ti (molar ratio) with respect to Ti atoms in the titanium-containing polyolefin.
It is 1000, preferably 0.5 to 500.

Ethyl silicate is a compound also called tetraethoxysilane. Even if other tetraalkoxysilane is used, the effect of the present invention cannot be obtained. The amount of ethyl silicate used is based on the Ti atoms in the titanium-containing polyolefin.
Si / Ti (molar ratio) is 0.1 to 1000, preferably 0.5 to 500.

In the present invention, in the combination of the above-mentioned organosilicon compound and ethyl silicate, a plurality of organosilicon compounds may be combined with ethyl silicate. The molar ratio of the organosilicon compound and the ethyl silicate can be appropriately determined depending on the type of the organosilicon compound used, the target molecular weight distribution, and the stereoregularity. It is suitable to use 10-fold moles, preferably 0.05 to 5-fold moles.

The order of adding these catalyst components is not particularly limited, and the organosilicon compound and ethyl silicate may be mixed and fed simultaneously, or may be fed separately. Further, these may be supplied after being contacted with or mixed with the organoaluminum compound in advance.

Other polymerization conditions, as long as the effect of the present invention is observed
Although not particularly limited, the following conditions are generally preferable. The polymerization temperature is 20 to 200 ° C., preferably 50 to 150 ° C., and hydrogen can be allowed to coexist as a molecular weight regulator. The polymerization may be slurry polymerization, solventless polymerization, gas phase polymerization, or the like, and may be a batch type, a semi-batch type, or a continuous type. Further, the polymerization is performed in two or more stages under different conditions. You can also The olefins to be polymerized are ethylene, propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, etc. These monomers are used alone or in combination of two or more. be able to. When two or more kinds of olefins are used, it is preferable to use 90% by mol or more of a specific kind from the viewpoint of improving stereoregularity of the obtained polyolefin.

(Effect) By adopting the method of the present invention, a polyolefin having good stereoregularity and a wide molecular weight distribution can be obtained. Therefore, the obtained polyolefin is excellent in fluidity and rigidity and is a material suitable for injection molding and film molding.

In the olefin polymerization method of the present invention, the reason why the molecular weight distribution of the polyolefin obtained by using a specific catalyst system is widened is not clear yet, but the present inventors consider as follows. That is, the present inventors have found that a high molecular weight component is produced when the organosilicon compound represented by the general formula [I] is used alone, while a low molecular weight component is produced when ethyl silicate is used alone. We found the interesting fact that they were produced, and presumed that the simultaneous use of these two species succeeded in producing two different active sites in the same system and broadening the molecular weight distribution. At the same time, in the present invention, the two types of active sites derived from the organosilicon compound and ethyl silicate are both isotactic, which leads to the achievement of both wide molecular weight distribution and high stereoregularity. thinking.

(Examples) The present invention is described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The measuring method will be described in the following examples.

(1) p-Xylene-soluble component 1 g of polymer was added to 100 cc of p-xylene, and the temperature was raised to 120 ° C with stirring, and stirring was continued for another 30 minutes to completely dissolve the polymer. -Xylene solution at 23 ℃,
I left it for 24 hours. The precipitate was filtered off and the p-xylene solution was completely concentrated to obtain a soluble component.

It is represented by room temperature p-xylene solubles (%) = (p-xylene solubles (g) / polymer 1g) × 100.

(2) Melt index (hereinafter abbreviated as MI) Compliant with ASTM D790 (3) Bending elastic modulus (hereinafter abbreviated as Fm) Japan Steel Works 63.6 mm x 12.7 by JI20SAII type injection molding machine
A test piece of mm × 0.31 mm was prepared, and the test was performed according to ASTM: D-790.

(4) Molecular weight distribution (hereinafter abbreviated as w / n) The ratio of the weight average molecular weight (w) to the number average molecular weight (n)
It was measured by the GPC (gel permeation chromatography) method. Waters GPC-150C o-
It was carried out at 135 ° C. using dichlorobenzene as a solvent.

(5) Spiral flow by an 8 ounce injection molding machine with a spiral mold attached
Injection molding was performed at 230 ° C., and after cooling the mold, the resin length from the weld portion was measured.

Example 1 [Preparation of titanium compound] The titanium component was prepared according to the method of Example 1 of JP-A-58-83006. That is, 0.95 g (10 mmol) of anhydrous magnesium chloride, 10 ml of decane, and 4.7 ml (30 mmol) of 2-ethylhexyl alcohol were heated and stirred at 125 ° C. for 2 hours, and 0.55 g (3.7 mg of phthalic anhydride was added to this solution.
5 mmol) was added, and the mixture was stirred and mixed at 125 ° C. for 1 hour to obtain a uniform solution. After cooling to room temperature, the whole amount was dropwise added to 40 ml (0.36 mmol) of titanium tetrachloride kept at -20 ° C over 1 hour. After the completion of charging, the temperature of this mixed solution was raised to 110 ° C over 2 hours, and when it reached 110 ° C, 0.54 ml (2.5 mmol) of diisobutylphthalate was added, and the mixture was stirred at the same temperature for 2 hours. I kept it underneath. Two
The solid portion was collected by the end of the reaction after hot filtration time, after resuspension in TiCl ₄ in the solid portion 200 ml, 2 hours again 110 ° C., heating was performed for the reaction. After the reaction was completed, the solid portion was collected again by hot filtration, and thoroughly washed with decane and hexane until no free titanium compound was detected in the washing liquid. Solid Ti catalyst component prepared by the above production method,
Stored as a heptane slurry. The composition of the solid Ti catalyst component is titanium 2.1% by weight, chlorine 57% by weight, magnesium 18.
It was 0% by weight and 21.9% by weight of diisobutyl phthalate.

[Preliminary polymerization]

Purified heptane 20 in 1 autoclave with N ₂ substitution
After charging 0 ml, 15 mmol of triethylaluminum, and 5 mmol of solid Ti catalyst component in terms of Ti atom, propylene was continuously introduced into the reactor for 1 hour so that the total amount of propylene was 10 g per 1 g of titanium component. The temperature during this period was kept at 15 ° C.
After 1 hour, the introduction of propylene was stopped, and the inside of the reactor was sufficiently replaced with N ₂ . The solid portion of the obtained slurry was washed 6 times with purified heptane to obtain a titanium-containing polyolefin.

〔polymerization〕

Autoclave having a content volume of 400 subjected to N ₂ substitution was charged with propylene 200, triethylaluminum 219mmo
l, diphenyldimethoxysilane 6.6mmol, ethyl silicate
After charging 26.3 mmol and 2.0 N of hydrogen, the internal temperature of the autoclave was raised to 65 ° C, 0.88 mmol of titanium-containing polyolefin was charged with titanium atoms, and then the internal temperature of the autoclave was raised to 70 ° C. The mixture was warmed and propylene was polymerized for 3 hours. Polymerization pressure 31 kg / cm ^2, during this period the temperature was kept at 70 ° C., 0.2 m while confirming the hydrogen concentration in the gas chromatograph
It was maintained at ol%. After 3 hours, unreacted propylene was purged to obtain a white granular polymer. Subsequently, the obtained polymer was washed with 200 heptane at 60 ° C. for 30 minutes and sufficiently dried.

The total polymer yield was 32 kg, and the activity at this time was 16000 g.
It was −pp / g-cat · 3 hr.

An antioxidant was added to the above polymer and mixed sufficiently, and then pelletized by a granulator.

The results of MI, p-xylene solubles, w / n, Fm, and spiral flow length are shown in Table 1.

Example 2 In the polymerization of Example 1, the same operation as in Example 1 was performed except that cyclohexylmethyldimethoxysilane, methylphenyldimethoxysilane and dimethyldimethoxysilane were used instead of diphenyldimethoxysilane. The results are shown in Table 1.

Example 3 In the polymerization of Example 1, the same operation as in Example 1 was performed except that the molar ratio of diphenyldimethoxysilane and ethyl silicate was used in the ratio shown in Table 1. The results are shown in Table 1.

Example 4 In the prepolymerization of Example 1, the same operation as in Example 1 was performed except that 5 mmol of iodine was added before adding the titanium component. The results are shown in Table 1.

Example 5 The same operation as in Example 1 was carried out except that 5 mmol of ethyl iodide was added before adding the titanium component in the prepolymerization of Example 1. The results are shown in Table 1.

Example 6 [Preparation of Titanium Compound] The titanium compound was prepared according to the method of Example 1 in JP-A-62-104810. That is, 100 g of aluminum trichloride (anhydrous) and 29 g of magnesium hydroxide were reacted while being crushed by a vibration mill at 250 ° C. for 3 hours. After completion of heating, the mixture was cooled in a nitrogen stream to obtain a solid product (I).

In a glass flask, 15 ml of purified decane, 2.5 g of solid product (I), 8.5 g of n-butyl orthotitanate, and 9.8 g of 2-ethyl-1-hexanol were mixed and stirred while stirring.
It was heated to 0 ° C. for 1.5 hours and dissolved to form a uniform solution. The solution was heated to 70 ° C., 1.8 g of ethyl p-toluate was added and reacted for 1 hour, 26 g of silicon tetrachloride was added dropwise over 2 hours with stirring to precipitate a solid, and the mixture was further stirred at 70 ° C. for 1 hour. . The solid was separated from the solution and washed with purified hexane to obtain a solid product (II).

30 ml of 1,2-dichloroethane in the total amount of the solid product (II)
And 30 ml of titanium tetrachloride with diisobutyl phthalate
After adding 1.5 g and reacting at 100 ° C for 2 hours with stirring, the liquid phase part was removed by decantation at the same temperature,
Again, 1,2-dichloroethane (30 ml), titanium tetrachloride (30 ml) and diisobutyl phthalate (1.5 g) were added, and the mixture was reacted at 100 ° C for 2 hours while stirring. Then, the solid portion was collected by hot filtration and washed with purified hexane, It was dried under reduced pressure at 25 ° C for 1 hour to obtain a solid product (III).

The solid product (III) is spherical and has an average particle size of 15 μm.
The particle size distribution was extremely narrow. This solid product (III) was used as a solid Ti catalyst component.

The compositional analysis results of the solid Ti catalyst component were as follows: Ti 3.0% by weight (hereinafter referred to as%), Cl 56.2%, Mg 17.6%, diisobutyl phthalate 20.1%, butoxy group 1.1%, 2-ethylhequinoxy group. 0.2% and 0.1% of p-toluate ethyl.

The subsequent prepolymerization and polymerization were carried out in the same manner as in Example 1.
The polymer obtained was molded in the same manner as in Example 1 and the physical properties were measured. The results are shown in Table 1.

Example 7 [Preparation of Titanium Compound] The titanium compound was prepared according to the method of Example 1 in JP-A-62-11706. That is, 50 ml of purified heptane, 50 ml of titanium tetrabutoxide, and 7.0 g of anhydrous magnesium chloride are added to a 500-ml glass three-necked flask (with a thermometer and a stir bar) purged with nitrogen.
Then, the flask was heated to 90 ° C. and the magnesium chloride was completely dissolved in 2 hours. Next, the flask was cooled to 40 ° C., and 10 ml of methyl hydrogen polysiloxane was added to precipitate a magnesium chloride / titanium tetrabutoxide complex. This was washed with purified heptane to give an off-white solid.

50 ml of a heptane slurry containing 10 g of the precipitated solid obtained above was introduced into a 300-ml glass three-necked flask (with a thermometer and a stir bar) which had been purged with nitrogen. Then, 20 ml of a heptane solution containing 5.8 ml of silicon tetrachloride was added at room temperature over 30 minutes, and the mixture was further reacted at 30 ° C. for 45 minutes. Further at 90 ℃ 1.
The reaction was carried out for 5 hours, and after completion of the reaction, the product was washed with purified heptane. Next, add 50 ml of a heptane solution containing 1.5 ml of diheptyl phthalate and react at 50 ° C. for 2 hours, then wash with purified heptane and add 25 ml of titanium tetrachloride to 90
The reaction was carried out at 0 ° C for 2 hours. This was washed with purified heptane to obtain a solid Ti catalyst component. The titanium content in the solid Ti catalyst component was 3.04% by weight. The subsequent prepolymerization and polymerization were carried out in the same manner as in Example 1. Further, the obtained polymer was molded in the same manner as in Example 1 and its physical properties were measured. The results are shown in Table 1.

Comparative Example 1 In the polymerization of Example 1, the same operation as in Example 1 was performed except that ethyl silicate was not used. The results are shown in Table 2.

Comparative Example 2 In the polymerization of Example 1, the same operation as in Example 1 was performed except that diphenyldimethoxysilane was not used.
The results are shown in Table 2.

Comparative Example 3 The same operation as in Example 1 was performed except that the prepolymerization was not performed. The results are shown in Table 2.

Comparative Example 4 In the polymerization of Example 1, the same operation as in Example 1 was performed except that methyltriethoxysilane, methyl silicate, isopropyl silicate, and butyl silicate were used instead of ethyl silicate. The results are shown in Table 2.

Comparative Example 5 Using the solid Ti catalyst component prepared in Example 6, the same polymerization as in Comparative Example 1 was performed. The results are shown in Table-2.

Comparative Example 6 Using the solid Ti catalyst component prepared in Example 7, the same polymerization as in Comparative Example 1 was performed. The results are shown in Table-2.

[Brief description of drawings]

FIG. 1 is a flow chart showing a typical polymerization procedure in the present invention.

Claims (1)

[Claims] 1. A titanium-containing polyolefin obtained by prepolymerization B An organoaluminum compound C General formula The method for producing a polyolefin, which comprises polymerizing an olefin in the presence of an organosilicon compound D ethyl silicate.