JPH10168113A - Highly crystalline polypropylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject polymer high in rigidity and thermal resistance by polymerizing propylene under controlled conditions in the presence of a solid titanium compound polymerization catalyst consisting of a specific solid titanium compound, an organoaluminum compound and a specific organosilicon compound. SOLUTION: This highly crystalline polypropylene is produced by polymerizing propylene under controlled conditions in the presence of a solid titanium compound polymerization catalyst consisting of (A) a solid titanium compound essentially containing magnesium, tetravalent titanium, a halogen and an electron-donor, (B) an organoaluminum compound and (C) an organosilicon compound of the formula R<1> R<2> Si(OR<3> )2 (R<1> to R<3> are each a 1-20C hydrocarbon group, wherein R<1> and/or R<2> is a linear hydrocarbon group with a tertiary carbon directly bound to Si, or a cyclic hydrocarbon group with a secondary carbon directly bound to Si), wherein the propylene is polymerized by controlling the polymerization conditions so that the resultant polypropylene has Si and Cl concentrations of <=10ppm, respectively, and isotactic pentad fraction of >=0.97.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel highly crystalline polypropylene. Specifically, it is a highly crystalline polypropylene that can exhibit high rigidity and heat resistance corresponding to high crystallinity.

[0002]

2. Description of the Related Art Polypropylene is widely used as a packaging material for sheets, films, etc., as well as structural materials for automobile parts, home electric parts and the like. In recent years, especially in the field of structural materials, high rigidity and heat resistance have been required,
There is an increasing need for highly crystalline polypropylene to satisfy this demand.

Conventionally, various proposals have been made for highly crystalline polypropylene. For example, JP-A-6-3297
No. 26 proposes a polypropylene having improved steric regularity and crystallinity, and improved rigidity and heat resistance by using a catalyst component comprising a solid titanium compound, an organoaluminum compound, and an organosilicon compound. Have been.

Japanese Patent Application Laid-Open No. Hei 4-202505 discloses that after a solid titanium catalyst component is prepolymerized with a specific α-olefin monomer, propylene is polymerized in the presence of an organoaluminum compound and a specific organosilicon compound. By doing so, a method for producing polypropylene having high stereoregularity and high crystallinity has been proposed.

As described above, in the method for producing highly crystalline polypropylene disclosed in the prior art, a high stereoregularity using a solid titanium compound, an organoaluminum compound, and an organosilicon compound as an electron donor compound. Catalyst systems are widely used.

[0006]

However, in order to sufficiently increase the stereoregularity of polypropylene, a relatively large amount of an organosilicon compound, which is an electron donor compound, is used, which not only decreases the polymerization activity. In addition, a large amount of the organosilicon compound remained in the polymer.

[0007] Regarding the influence of the organosilicon compound remaining in such a polymer, Japanese Patent Application Laid-Open No. 8-151407 discloses that the remaining organosilicon compound forms a siloxane compound or the like, and thus the physical properties of the product, especially the rigidity, are reduced. It has been shown that this has an adverse effect, and is reduced by about 10% as compared with the inherent rigidity of the polymer. And in the said method, in order to prevent the influence of the said organosilicon compound,
It is disclosed that a specific oxygen-containing hydrocarbon compound is used as an electron donor compound instead of an organosilicon compound.

Although the reduction of rigidity of polypropylene due to the remaining organosilicon compound has been solved by such means, the stereoregularity of the resulting polymer is sacrificed to some extent, and the stereoregularity of polypropylene has not yet been improved. There was room.

Accordingly, an object of the present invention is to provide a highly crystalline polypropylene having both high stereoregularity and high rigidity corresponding to the stereoregularity.

[0010]

Means for Solving the Problems The present inventors have intensively studied highly crystalline polypropylene in order to solve these problems. As a result, in a highly crystalline polypropylene obtained by a catalyst system using an organosilicon compound as an electron donor, even when some organosilicon compound remains, the amount of the organosilicon compound is reduced to a specific amount or less, and By reducing the concentration of chlorine coexisting with the organosilicon compound to a specific amount or less, the organosilicon compound can extremely effectively prevent a phenomenon that causes a decrease in physical properties of the product, particularly, rigidity by generating a siloxane compound or the like. This led to the completion of the present invention.

That is, the present invention provides that the isotactic pentad fraction (mmmm) is 0.97 or more, and that the concentration of silicon atoms and the concentration of chlorine atoms contained in the polymer are respectively 10 ppm or less. It is a highly crystalline polypropylene that is characterized.

In the present invention, polypropylene is a generic term for a homopolymer of propylene and a copolymer containing less than 5 mol% of α-olefins other than propylene and propylene. Examples of the α-olefin other than propylene include ethylene, 1-butene, and 3-methylbutene.
Examples thereof include 1,1-hexene, 4-methylpentene-1,1-octene, and vinylcyclohexene.

The stereoregularity of the highly crystalline polypropylene of the present invention is 0.97 or more, and preferably 0.98 or more, in the measurement of the isotactic pentad fraction determined by ¹³ C-NMR. That is all.

It is preferable that the high crystalline polypropylene has a soluble amount of p-xylene at room temperature of 1.0% by weight or less, preferably 0.5% by weight or less.

In the highly crystalline polypropylene of the present invention, the concentration of silicon atoms contained in the polymer is based on the remaining amount of the organosilicon compound used as a catalyst component.

In order to sufficiently exhibit the original performance of the highly crystalline polypropylene of the present invention, the concentration of silicon atoms contained in the polymer must be 10 ppm or less, and the concentration of chlorine atoms, which will be described in detail later, is required. Important in combination with That is, when the silicon atom concentration exceeds 10 ppm, even if the chlorine atom concentration is satisfied, the original performance of the highly crystalline PP, particularly the rigidity, is not sufficiently exhibited. A more preferred concentration of silicon atoms is 5 ppm or less.

The chlorine atom concentration contained in the polymer of the highly crystalline polypropylene of the present invention may be determined by adjusting the concentration of a titanium tetrachloride compound in a solid titanium compound used as a catalyst component, a chlorine atom in a titanium trichloride compound, or the following. A chlorine atom based on a carrier component such as magnesium chloride used as a carrier of a supported solid titanium compound as described in detail in further detail, and a chlorine atom based on a halogenated organoaluminum compound component containing a chlorine atom as an organoaluminum compound Is involved.

In order to sufficiently exhibit the original performance of the highly crystalline polypropylene in the present invention, it is important that the concentration of chlorine atoms contained in the polymer is 10 ppm or less. That is, the concentration of chlorine atoms contained in the polymer is 1
When the content exceeds 0 ppm, even when the organosilicon compound slightly remains in the polymer, a hydrolysis reaction occurs in the presence of a chlorine atom, and further a siloxane compound is formed by an intermolecular condensation reaction. The rigidity is reduced, and the rigidity of the polymer obtained at the same time, for example, the rigidity between lots of the product varies, making it difficult to reproduce stable high rigidity. In view of the above, a more preferable chlorine atom concentration is 5 ppm or less.

The fact that chlorine atoms present in the above-mentioned polypropylene affects a trace amount of the organosilicon compound remaining in the polypropylene has been clarified for the first time based on the knowledge of the present inventors. By limiting the amount of chlorine atoms and silicon compounds present to specific amounts, it is possible to use an organosilicon compound that is extremely effective to achieve high crystallinity, and to achieve high crystallinity of polypropylene. High rigidity that meets the requirements has been made possible.

In the present invention, the concentration of other atoms based on the catalyst component is not particularly limited.
Titanium atom concentration is 2 ppm or less, preferably 1 ppm
Below, and the magnesium atom is usually 10 ppm
Or less, preferably 8 ppm or less. In the present invention, the above-mentioned measurement of the atomic concentration in the polymer is a value obtained by X-ray fluorescence.

In the present invention, the melt flow rate of the highly crystalline polypropylene is preferably in the range of 0.1 to 300 g / 10 minutes. Melt flow rate is 0.1g / 10
If it is less than 300 minutes, or more than 300 g / 10 minutes, the moldability becomes difficult and the original performance of the highly crystalline PP is not achieved. The preferred range of the melt flow rate of the present invention is in the range of 0.5 to 200 g / 10 minutes.

The highly crystalline polypropylene of the present invention may contain various nucleating agents or additives such as inorganic fillers in order to exhibit higher rigidity.

The method for producing the highly crystalline polypropylene of the present invention is not particularly limited, and the specific isotactic pentad fraction and the silicon and chlorine atoms contained in the polymer described above are not limited. 10 pp each
Any method can be adopted as long as it is controlled to m or less.

If a typical production method is illustrated, the following method is preferable.

That is, the following components [A], [B] and [C]
A highly crystalline polypropylene characterized by polymerizing propylene in the presence of a solid titanium compound polymerization catalyst, and controlling the polymerization conditions so that the concentration of silicon atoms and the concentration of chlorine atoms in the obtained polypropylene are each 10 ppm or less. It is a manufacturing method of.

[A] Solid titanium compound containing magnesium, tetravalent titanium, halogen and electron donor as essential components [B] Organoaluminum compound [C] Organosilicon compound represented by general formula [I] R ¹ R ² Si (OR ³ ) ₂ [I] (where R ¹ R ² and R ³ are the same or different and are each a hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ¹ and R ² is a silicon atom Is a chain hydrocarbon in which an atom directly bonded to is a tertiary carbon or a cyclic hydrocarbon in which a secondary hydrocarbon is used.) In the present invention, the solid titanium compound is magnesium, tetravalent titanium, halogen, As long as it contains an electron donor as an essential component, known ones are used without particular limitation. The method for producing such a solid titanium compound is as follows:
Many proposals have been made so far, and in the present invention, solid titanium compounds obtained by these known methods are used without any limitation. For example, a method in which a titanium compound such as a titanium tetrahalide is co-ground with a magnesium compound in the presence of an electron donor, a method in which a titanium compound, a magnesium compound and an electron donor are brought into contact in a solvent, and the like are exemplified.

The method for preparing these solid titanium compounds is as follows:
For details, see JP-A-56-155206 and JP-A-56-155206.
136806, 57-34103, 58-870
6, 58-83006, 58-138708, 5
8-183709, 59-206408, 59-2
19311, 60-81208, 60-8120
9, 60-186508, 60-192708, 61-211309, 61-271304, 62-
15209, 62-11706, 62-7270
2, 62-104810 and the like.

As the titanium compound used for preparing the solid titanium compound, a tetravalent titanium compound is used. As such a tetravalent titanium compound, titanium halides such as tetrahalogenated titanium, tetraalkoxytitanium, trihalogenated alkoxytitanium, dihalogenated dialkoxytitanium and halogenated trialkoxytitaniums can be used. Specific examples of such a compound include tetrachlorotitanium, tetrabromotitanium, tetraiodotitanium, tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetra-i-propoxytitanium, tetra-n-butoxytitanium, i-butoxytitanium, tetra-n-hexyloxytitanium, tetra-n-octyloxytitanium, trichloroethoxytitanium, dichlorodiethoxytitanium, triethoxychlorotitanium, trichloron-butoxytitanium, dichlorodin-butoxytitanium, trin-butoxychloro Titanium or the like can be used.

The magnesium compound used for preparing the solid titanium compound described above includes magnesium halides such as magnesium chloride, alkoxymagnesiums such as magnesium diethoxide, alkoxymagnesium halides, magnesium oxide, magnesium hydroxide, and magnesium carbonate. Acid salts and the like can be used.

Further, electron donors used for preparing the solid titanium compound include alcohols, phenols, ketones, aldehydes, carboxylic acids, organic acid halides, esters of organic or inorganic acids, and ethers. Examples thereof include ter, acid amide, acid anhydride, ammonia, amine, nitrile, and isocyanate.

Of these, organic acid esters are preferable, and compounds having two or more ester bonds in the molecule are particularly preferable.

Examples of such compounds having two or more ester bonds in the molecule include diethyl succinate, dibutyl succinate, diethyl methyl succinate, and the like.
Diisobutyl α-methylglutarate, diethyl methylmalonate, diethyl ethylmalonate, diethyl isopropylmalonate, diethyl butylmalonate, diethyl phenylmalonate, diethyl diethylmalonate, diethyldibutylmalonate, monooctyl maleate, dioctyl maleate Aliphatic polycarboxylic acid esters such as dibutyl maleate, dibutyl butyl maleate, diethyl butyl maleate, diisopropyl β-methylglutarate, diallyl ethyl succinate, di-2-ethylhexyl fumarate, diethyl itaconate, and dioctyl citracone; Diethyl 1,2-cyclohexanecarboxylate, 1,
Alicyclic polycarboxylic acid esters such as diisobutyl 2-cyclohexanecarboxylate, diethyl tetrahydrophthalate, diethyl nadicate, monoethyl phthalate, dimethyl phthalate, methylethyl phthalate, monoisobutyl phthalate, diethyl phthalate, phthalic acid Ethyl isobutyl, di-n-propyl phthalate, diisopropyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, di-n-heptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, dineopentyl phthalate And aromatic polycarboxylic esters such as didecyl phthalate, benzyl butyl phthalate, diphenyl phthalate, diethyl naphthalene dicarboxylate, dibutyl naphthalene dicarboxylate, triethyl trimetate, and dibutyl trimetate. Can.

Other examples of the compound having two or more ester bonds in the molecule include diethyl adipate,
Diisobutyl adipate, diisopropyl sebacate,
Di-n-butyl sebacate, di-n-octyl sebacate,
Long chain dicarboxylic acid esters such as di-2-ethylhexyl sebacate can be mentioned.

Of these, the use of phthalic esters is preferred because it is effective in the effects of the present invention.

In the present invention, as the organoaluminum compound constituting the propylene polymerization catalyst, an organoaluminum compound having substantially no halogen atom is suitably used to achieve high polymerization activity. As the organoaluminum compound having substantially no halogen atom,
Known ones are used. For example, a trialkylaluminum represented by the following general formula [II] can be mentioned.

R ₃ Al [II] (R is a saturated hydrocarbon group having 1 to 10 carbon atoms.) In the general formula [II], R is a saturated hydrocarbon group having 1 to 10 carbon atoms. . Examples of the saturated hydrocarbon group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group and a t-butyl group.
Butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl,
Examples include a chain alkyl group such as a decyl group, a cyclopentyl group, and a cyclohexyl group, and a cyclic alkyl group.

Specific examples of trialkylaluminum compounds that can be used particularly preferably include, for example, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-nbutylaluminum, tri-ibutylaluminum, tri-n Hexyl aluminum, tri-n-octyl aluminum,
Tri-n-decyl aluminum and the like.

The proportion of the solid titanium catalyst and the organoaluminum compound having substantially no halogen atom is not particularly limited. In general, the Al atom in the organoaluminum compound is preferably 10 to 1000 (molar ratio) to the Ti atom in the solid titanium catalyst in terms of Al / Ti (molar ratio), and particularly preferably 20 to 500.

Also, the propylene polymerization catalyst of the present invention includes:
Other components can be contained as long as the properties are not significantly reduced. For example, components such as an organoaluminum halide compound inevitably contained in the preparation of a solid titanium catalyst described later and a compound generated in the preparation of a solid titanium compound are exemplified.

The organosilicon compound used in the present invention is
The compound represented by the following general formula [I] is used without any limitation.

R ¹ R ² Si (OR ³ ) ₂ [I] (where R ¹ R ² and R ³ are the same or different hydrocarbon groups each having 1 to 20 carbon atoms, and R ¹ and R ² Is a chain hydrocarbon in which the atom directly bonded to the silicon atom is a tertiary carbon or a cyclic hydrocarbon in which the atom is a secondary hydrocarbon.) Examples of the hydrocarbon group having 1 to 20 carbon atoms include methyl Groups, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, and as described below. Cyclopentyl, alkyl-substituted cyclopentyl, cyclohexyl, alkyl-substituted cyclohexyl, t-butyl, t-amyl and the like.

Examples of the chain hydrocarbon group in which the atom directly connected to the silicon atom is tertiary carbon include t-butyl and t-butyl.
Amyl groups and the like. Examples of the cyclic hydrocarbon group in which the atom directly linked to the silicon atom is a secondary carbon include a cyclopentyl group, a 2-methylcyclopentyl group, a 3-methylcyclopentyl group, a 2-ethylcyclopentyl group,
-N-butylcyclopentyl group, 2,3-dimethylcyclopentyl group, 2,4-dimethylcyclopentyl group,
2,5-dimethylcyclopentyl group, 2,3-diethylcyclopentyl group, 2,3,4-trimethylcyclopentyl group, 2,3,5-trimethylcyclopentyl group,
2,3,4-triethylcyclopentyl group, tetramethylcyclopentyl group, tetraethylcyclopentyl group,
Cyclohexyl group, 2-methylcyclohexyl group, 3-
Methylcyclohexyl group, 4-methylcyclohexyl group, 2-ethylcyclohexyl group, 2,3-dimethylcyclohexyl group, 2,4-dimethylcyclohexyl group,
2,5-dimethylcyclohexyl group, 2,6-dimethylcyclohexyl group, 2,3-diethylcyclohexyl group, 2,3,4-trimethylcyclohexyl group, 2,
3,5-trimethylcyclohexyl group, 2,3,6-trimethylcyclohexyl group, 2,4,5-trimethylcyclohexyl group, 2,4,6-trimethylcyclohexyl group, 2,3,4-triethylcyclohexyl group, 2,
3,4,5-tetramethylcyclohexyl group, 2,3
4,6-tetramethylcyclohexyl group, 2,3,5
6-tetramethylcyclohexyl group, 2,3,4,5-
Examples thereof include a tetraethylcyclohexyl group, a pentamethylcyclohexyl group, and a pentaethylcyclohexyl group.

Specific examples of the above-mentioned organosilicon compound are as follows. For example, di-t-butyldimethoxysilane, t-butylethyldimethoxysilane, di-t-amyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, di (2-methylcyclopentyl) dimethoxysilane, di (3-methylcyclopentyl) dimethoxy Silane, di (2-ethylcyclopentyl) dimethoxysilane, di (2,3-dimethylcyclopentyl) dimethoxysilane, di (2,4-dimethylcyclopentyl) dimethoxysilane, di (2,5
-Dimethylcyclopentyl) dimethoxysilane, di (2,3-diethylcyclopentyl) dimethoxysilane, di (2,3,4-trimethylcyclopentyl) dimethoxysilane, di (2,3,5-trimethylcyclopentyl) dimethoxysilane, di (2 , 3,4-triethylcyclopentyl) dimethoxysilane, di (tetramethylcyclopentyl) dimethoxysilane, di (tetraethylcyclopentyl) dimethoxysilane, di (2-methylcyclohexyl) dimethoxysilane, di (3-methylcyclohexyl) dimethoxysilane, di ( 4-methylcyclohexyl) dimethoxysilane, di (2-ethylcyclohexyl) dimethoxysilane, di (2,3-dimethylcyclohexyl) dimethoxysilane, di (2,4-dimethylcyclohexyl) dimet Shishiran, di (2,5-dimethylcyclohexyl) dimethoxysilane, di (2,6
Dimethylcyclohexyl) dimethoxysilane, di (2,
3-diethylcyclohexyl) dimethoxysilane, di (2,3,4-trimethylcyclohexyl) dimethoxysilane, di (2,3,5-trimethylcyclohexyl)
Dimethoxysilane, di (2,3,6-trimethylcyclohexyl) dimethoxysilane, di (2,4,5-trimethylcyclohexyl) dimethoxysilane, di (2,4
6-trimethylcyclohexyl) dimethoxysilane, di (2,3,4-triethylcyclohexyl) dimethoxysilane, di (2,3,4,5-tetramethylcyclohexyl) dimethoxysilane, di (2,3,4,6-tetra Methylcyclohexyl) dimethoxysilane, di (2,
3,5,6-tetramethylcyclohexyl) dimethoxysilane, di (2,3,4,5-tetraethylcyclohexyl) dimethoxysilane, di (pentamethylcyclohexyl) dimethoxysilane, di (pentaethylcyclohexyl) dimethoxysilane, t-butyl Methyldimethoxysilane, t-butylethyldimethoxysilane, t-amylmethyldimethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentylethyldimethoxysilane, cyclopentylisobutyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane, cyclohexylisobutyldimethoxysilane, etc. be able to. Among them, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, t-butylethyldimethoxysilane and the like are preferable. The amount of the organosilicon compound used is not particularly limited, but T
Si atoms in the organosilicon compound are Si / T
It is preferable to use i in an amount of 0.01 to 100 (molar ratio), more preferably 0.05 to 10 in an amount.

In the present invention, the above solid titanium compound component can be preliminarily polymerized with an olefin in the presence of an organoaluminum compound and an electron donor compound under mild conditions of prepolymerization described below.

As the prepolymerization conditions for the olefin, known conditions are employed without any particular limitation as long as the above-mentioned effects are observed.

Generally, as the above-mentioned organoaluminum compound used in the prepolymerization, a trialkylaluminum represented by the above general formula [II] can be used. Preferred examples of the organoaluminum compound include triethylaluminum, triisobutylaluminum, and a combination of triethylaluminum or triisobutylaluminum and diethylaluminum chloride, ethylaluminum sesquichloride, or ethylaluminum dichloride.

The amount of the organoaluminum compound used in the prepolymerization is not particularly limited, but generally, the Al atom in the organoaluminum is Al / Ti (molar) with respect to the Ti atom in the solid titanium compound component. (Ratio) is preferably 1 to 100, and more preferably 3 to 10.

In the prepolymerization, other organoaluminum compounds such as halogenated organoaluminum compounds may be present as long as the action of the organoaluminum compound is not significantly impaired.

In the above-mentioned prepolymerization, ether, amine, amide, etc. may be added, if necessary, to control the stereoregularity of the resulting solid titanium catalyst to the polyolefin in addition to the solid titanium compound component and the organoaluminum compound. And an electron donor such as a sulfur-containing compound, a nitrile, a carboxylic acid, an acid amide, an acid anhydride, an acid ester, and an organosilicon compound. Among them, it is preferable to use an organosilicon compound. As the organosilicon compound, the same compounds as those represented by the above general formula [I] can be used, and in addition, dimethyldimethoxysilane, diethyldimethoxysilane, dipropyldimethoxysilane, divinyldimethoxysilane, diallyldimethoxy Silane, diphenyldimethoxysilane, methylphenyldimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, butyltriethoxysilane, pentyltriethoxysilane, isopropyltriethoxysilane,
Hexyltriethoxysilane, octyltriethoxysilane, dodecyltriethoxysilane, allyltriethoxysilane and the like can also be used. Also, a plurality of the above compounds can be used simultaneously.

The amount of the organosilicon compound used in the prepolymerization is not particularly limited, but generally, Si / Ti is used for the Ti atom in the solid titanium compound component.
(Molar ratio) is preferably from 0.1 to 10, and more preferably from 0.5 to 5.

The amount of the olefin polymerized in the prepolymerization is 0.1 to 100 g per 1 g of the solid titanium compound component.
It is preferably in the range of 1 to 100 g, and industrially 2 to 100 g.
A range of 50 g is preferred. As the olefin used in the prepolymerization, ethylene, propylene, 1-butene, 1-
Examples thereof include linear olefins such as pentene and 1-hexene.

In this case, it is possible to use two or more of the above-mentioned olefins at the same time, and it is also possible to use different olefins at each stage by performing the prepolymerization stepwise. In consideration of the improvement in the stereoregularity of the obtained polymer, it is preferable to use a specific type of olefin at 90 mol% or more. It is also possible to make hydrogen coexist in the preliminary polymerization.

The prepolymerization has a polymerization rate of 0.001 to 0.001.
It is preferable to carry out in the range of 1.0 g-polymer / g-catalyst-minute, and in order to achieve such a polymerization rate, usually, slurry polymerization is most suitably employed. In this case, a saturated aliphatic hydrocarbon or an aromatic hydrocarbon such as hexane, heptane, cyclohexane, benzene, and toluene can be used alone or in combination.

The temperature in the slurry polymerization is generally -2.
The temperature is preferably from 0 to 100 ° C., particularly preferably from 0 to 60 ° C. When preliminary polymerization is carried out in multiple stages, it may be carried out under different temperature conditions in each stage. Further, the polymerization time may be appropriately determined according to the polymerization temperature and the polymerization amount. Further, the polymerization pressure is not limited, but is generally from atmospheric pressure to about 5 kg / cm ² .

The prepolymerization may be carried out in any of batch, semi-batch and continuous methods.

Although the preliminary polymerization method by slurry polymerization has been described above, it is also possible to carry out the preliminary polymerization by gas phase polymerization or solventless polymerization.

After obtaining a solid titanium catalyst by the above prepolymerization, the solid titanium catalyst is used alone or as a mixture of saturated aliphatic hydrocarbons or aromatic hydrocarbons such as hexane, heptane, cyclohexane, benzene and toluene. Washing is preferred in order to obtain an olefin polymerization catalyst having higher polymerization activity. The number of times of such washing is usually preferably 5 to 6 times.

The conditions for polymerizing propylene (main polymerization) using a propylene polymerization catalyst comprising a solid titanium compound, an organoaluminum compound and a specific organosilicon compound, which can be obtained by the above-mentioned method, are as follows. As long as the concentration is set so that the concentration of silicon atoms and the concentration of chlorine atoms are each 10 ppm or less, other conditions can be employed without particular limitation using known methods. Generally, the following conditions are preferred.

The polymerization rate in the main polymerization is generally 10
~ 1000 g-polymer / g-catalyst-min, preferably
It is desirable to adjust to a range of 50 to 700 g-polymer / g-catalyst-minute.

The polymerization temperature during the main polymerization is from 20 to 20.
The temperature is 0 ° C, preferably 50 to 150 ° C, and hydrogen may be allowed to coexist as a molecular weight regulator. Also, the polymerization is
It can be applied to slurry polymerization, solventless polymerization, and gas phase polymerization, and may be any of batch, semi-batch, and continuous methods, and may be performed in two or more stages under different conditions. The polymerization time may be appropriately determined in consideration of the above-mentioned polymerization temperature and polymerization mode, but is usually set in the range of 2 hours to 8 hours, preferably 3 hours to 6 hours.

In the above main polymerization, the control of the concentration of silicon atoms and the concentration of chlorine atoms in the obtained highly crystalline polypropylene to be 10 ppm or less, respectively, depends on the amount of the catalyst used. 1g of titanium compound
It is preferably 50,000 g or more, more preferably 60,000 g or more.

Further, the concentration of silicon atoms remaining in the highly crystalline polypropylene obtained by the main polymerization can be reduced by adding a washing operation of the polypropylene obtained as the polymerization conditions. Therefore,
In order to further reduce the concentration of silicon atoms, it is preferable to perform the following washing operation.

A) After the polymerization is completed, a new liquid propylene is added to the polymerization tank, and the mixture is sufficiently stirred, left standing to settle the polymer particles, and the liquid propylene is extracted from the upper part of the polymerization tank with a nozzle.

B) The polymer slurry is passed through a liquid cyclone to recirculate much of the liquid propylene containing the organosilicon compound into the polymerization tank, and the slurry in which the polymer particles are concentrated is sent to a flash tank and an evaporating tank for liquid propylene. And a method of evaporating an inert hydrocarbon solvent and the like.

C) A polymer slurry is introduced from the upper part of the countercurrent washing tower, and fresh liquid propylene or C7
The following is a method of supplying an inert hydrocarbon which is relatively easy to evaporate, and washing and separating the polymer particles while allowing them to settle.

D) A method in which the entire amount of the polymer slurry is sent to an evaporation tank, flushed, washed with an inert hydrocarbon solvent having 7 or less carbon atoms or liquid propylene, and then a liquid portion is separated.

By the above method, the concentration of silicon atoms in the polymer can be reduced to 5 ppm or less, and the effect of the present invention can be further improved.

[0068]

As will be understood from the above description, according to the present invention, a highly crystalline polypropylene having high stereoregularity and having high rigidity corresponding to the crystallinity of the polypropylene are obtained. Provided. According to the present invention, there is also provided a production method capable of producing the above-mentioned highly crystalline polypropylene stably.

[0069]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The measurement method used in the following examples will be described.

(1) Melt Index (hereinafter abbreviated as MI) This was based on ASTM D-1238.

(2) Measurement of Concentration of Silicon and Chlorine Atoms Remaining in Polymer About 10 g of polymer was pressed at 230 ° C. to form a disk-shaped sheet, and then a fully automatic fluorescent X-ray made by Rigaku Denki Co., Ltd. The measurement was performed using the analyzer system 3080.

(3) Pentad fraction Macromolecules, 6 , 925 by Zambelli et al.
(1973), that is, ¹³ C-NMR was used to determine the isotactically bound fraction of five consecutive monomers in the polymer molecular chain. Measurement is JEOL
Pulse width 90 °, pulse interval 1 using GSX-270
The test was performed for 5 seconds with a total of 10,000 times. Macl peak assignment
omolecules, 8 , 697 (1975).

(4) Soluble content of p-xylene 1 g of polymer was added to 100 ml of p-xylene, and the temperature was raised to 120 ° C. with stirring.
After the polymer was completely dissolved, p-xylene solution was added to 23
C. and left for 24 hours. The precipitate was separated by filtration, and a p-xylene solution was completely concentrated to obtain a soluble component.

Room temperature p-xylene solubles (%) = (p-xylene solubles)
(g) / 1 g of polymer) × 100.

(5) Flexural modulus (hereinafter abbreviated as “Fm”) According to ASTM D790.

(6) Fm Coefficient of Variation The percentage of the standard deviation relative to the average Fm value was shown.

Example 1 [Preparation of solid titanium compound] The solid titanium compound was prepared according to the method of Example 1 in JP-A-58-83006.

That is, 0.95 g of anhydrous magnesium chloride
(10 mmol), 10 ml of decane and 4.7 ml (30 mmol) of 2-ethylhexyl alcohol in 125
The mixture was heated and stirred at ℃ for 2 hours. 0.55 g (6.75 mmol) of phthalic anhydride was added to this solution, and the mixture was further stirred and mixed at 125 ° C. for 1 hour to obtain a uniform solution. After cooling to room temperature, 40m of titanium tetrachloride kept at -20 ° C
1 (0.36 mol) over 1 hour. Then, the temperature of the mixed solution was raised to 1 for 2 hours.
The temperature was raised to 10 ° C., and when it reached 110 ° C., 0.54 ml of diisobutyl phthalate was added.
It was kept under stirring at 10 ° C. After completion of the reaction for 2 hours, the mixture was filtered to collect a solid part, and this solid part was treated with 200 ml of
After resuspension in l _4, it was heated 2 hours of reaction again at 110 ° C.. After completion of the reaction, a solid portion was collected again by hot filtration, and sufficiently washed with decane and hexane until no free titanium compound was detected in the washing solution. The composition of the solid titanium compound was 2.1% by weight of titanium, 57% by weight of chlorine, 18.0% of magnesium, and 21.9% by weight of diisobutyl phthalate.

[Preliminary polymerization] 1 liter of internal volume with N ₂ substitution
After charging 200 ml of purified n-hexane, 50 mmol of triethylaluminum, 10 mmol of dicyclopentyldimethoxysilane, and 5 mmol of solid titanium compound component in terms of Ti atom, the propylene was adjusted to about 2 g per 1 g of solid titanium catalyst component. 3
It was continuously introduced into the autoclave for 0 minutes. The temperature during this period was kept at 10 ° C. After 30 minutes, the reaction was stopped, and the inside of the autoclave was sufficiently replaced with N ₂ . The solid part of the obtained slurry was washed four times with purified n-hexane to obtain a solid titanium catalyst. As a result of analyzing the solid titanium catalyst, 2.1 g of propylene was polymerized per 1 g of the solid titanium compound component.

[Main polymerization] N ₂ -substituted internal volume 400
After 100 kg of propylene was added to 1 l of the polymerization vessel, 75 mmol of triethylaluminum, 37.5 mmol of dicyclopentyldimethoxysilane, and hydrogen gas were charged, the internal temperature of the polymerization vessel was raised to 65 ° C. The obtained solid titanium catalyst is 0.25 mm as Ti atom.
ol was charged. Subsequently, the internal temperature of the polymerization tank was raised to 70 ° C., and polymerization was performed for 6 hours. After completion of the polymerization, the reaction was stopped by adding 50 ml of methanol as a polymerization terminator, and then 30 kg of liquid propylene was added to the polymerization tank. After stirring for 1 hour, the mixture was allowed to stand to precipitate polymer particles, and the liquid propylene portion was removed. It was withdrawn from the top of the polymerization tank with a withdrawal nozzle. The polymer slurry in the polymerization tank was sent to a flash tank and separated from unreacted propylene to obtain a white granular polymer. An antioxidant was added to the above polymer, mixed well, and then pelletized by a granulator. In this example, the operation of the main polymerization was performed five times, and the physical properties of five lots were evaluated. The results are shown in Table 1.

Example 2 The same operation as in Example 1 was performed except that t-butylethyldimethoxysilane was used instead of dicyclopentyldimethoxysilane used in the main polymerization of Example 1. The results are shown in Table 1.

Example 3 The same operation as in Example 1 was carried out except that 25 mmol of t-butylethyldimethoxysilane was used instead of dicyclopentyldimethoxysilane used in the prepolymerization of Example 1. The results are shown in Table 1.

Example 4 [Preparation of solid titanium compound] A solid titanium compound was prepared according to the method of Example 1 of JP-A-7-292029.

That is, 10 g of diethoxymagnesium and 80 ml of toluene were charged into a 200-ml round-bottom flask which was sufficiently replaced with nitrogen gas and equipped with a stirrer.
It was in a suspended state. Then, the titanium tetrachloride 20 was added to the suspension.
The temperature was raised to 80 ° C., and 2.7 ml of di-n-butyl phthalate was added.
10 ° C. Thereafter, the mixture was reacted while stirring at a temperature of 110 ° C. for 2 hours. After the reaction, 90
Washed twice with 100 ml of toluene at 20 ° C., and newly added 20 ml of titanium tetrachloride and 80 ml of toluene.
And reacted while stirring for 2 hours. After the completion of the reaction, the solid was washed 10 times with 100 ml of n-heptane at 40 ° C. to obtain a solid titanium compound. The solid-liquid in the solid titanium compound was separated, and the content of titanium in the solid content was measured to be 2.91% by weight.

Then, prepolymerization and main polymerization were carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 5 The same operation as in Example 1 was performed except that the propylene washing after the main polymerization in Example 1 was not performed. The results are shown in Table 1.

COMPARATIVE EXAMPLES 1-2 Except for using ethyl silicate instead of dicyclopentyldimethoxysilane used in the main polymerization of Example 1 (Comparative Example 1), and using diphenyldimethoxysilane (Comparative Example 2), The same operation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 3 The same operation as in Example 1 was carried out except that the main polymerization time in Example 1 was changed to 1 hour. The results are shown in Table 1.

Comparative Example 4 The same operation as in Example 1 was performed except that the main polymerization time in Example 1 was changed to 1 hour, and propylene washing after the main polymerization was not performed. The results are shown in Table 1.

[0090]

[Table 1]

Claims (4)

[Claims] Claims: 1. Isotactic pentad fraction (mm
mm) is 0.97 or more, and the concentration of silicon atoms and the concentration of chlorine atoms contained in the polymer are each 10 ppm.
Highly crystalline polypropylene characterized by the following. 2. Propylene is polymerized in the presence of a solid titanium compound polymerization catalyst comprising the following components [A], [B] and [C], and the resulting polypropylene has a silicon atom concentration and a chlorine atom concentration of 10 ppm or less, respectively. So that
A method for producing a highly crystalline polypropylene, comprising controlling polymerization conditions. [A] Solid titanium compound containing magnesium, tetravalent titanium, halogen and an electron donor as essential components [B] Organoaluminum compound [C] Organosilicon compound represented by general formula [I] R ¹ R ² Si ( OR ³ ) ₂ [I] (where R ¹ R ² and R ³ are the same or different and are each a hydrocarbon group having 1 to 20 carbon atoms, and at least one of R ¹ and R ² is directly bonded to a silicon atom. Is a chain hydrocarbon having a tertiary carbon atom or a cyclic hydrocarbon having a secondary hydrocarbon atom.) 3. The polymerization is carried out under polymerization conditions in which the polymerization amount per gram of solid titanium compound is 50,000 g or more.
A method for producing the highly crystalline polypropylene as described above. 4. The method for producing a highly crystalline polypropylene according to claim 2, wherein the obtained polymer is washed with a hydrocarbon-based medium to reduce the concentration of silicon atoms in the obtained polypropylene to 5 ppm or less. .