JP3139524B2 - Propylene homopolymer and biaxially stretched film using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propylene homopolymer, and more particularly, to a biaxially oriented polypropylene film which retains its heat resistance and has surface properties such as stretchability, transparency and antistatic performance. The present invention relates to a propylene homopolymer and a biaxially stretched film which provide a biaxially stretched polypropylene film having an improved value.

[0002]

2. Description of the Related Art Stretched polypropylene films are used not only for packaging food packaging, clothing packaging, pharmaceutical packaging, miscellaneous goods packaging, but also for laminates such as decorative boards, plywood and metal sheets for building materials and various decorative boards. For mold release material during molding
Alternatively, it is used for book covers, decorative boxes, food cases, and the like. Among these polypropylene-based stretched films, biaxially stretched polypropylene films are excellent in heat resistance, tensile strength, impact strength, gas permeability, stiffness, and the like. However, in the biaxially stretched polypropylene film, since the orientation and crystallinity of the film are significantly increased by stretching and heat setting, the transparency and the antistatic performance exhibited by transferring the additive to the surface are not sufficient. Therefore, means for improving these characteristics have been desired. Conventionally, random copolymerization of propylene and ethylene has been known as a means for reducing the crystallinity of a polypropylene resin to improve stretchability, transparency, and antistatic performance (Japanese Patent Publication No. 4-22923, Tokuhei 3-43
No. 71). However, such copolymerization with ethylene lowers the melting point of the resulting polypropylene-based resin, thus causing a problem that the heat resistance characteristic of the biaxially stretched polypropylene film is significantly impaired.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention is intended to maintain the heat resistance characteristic of a biaxially oriented polypropylene film and to improve the surface properties such as stretchability, transparency and antistatic performance. It is an object of the present invention to provide a propylene homopolymer and a biaxially stretched film which provide a biaxially stretched polypropylene film having improved propylene.

[0004]

The present inventors have conducted intensive studies to develop a propylene homopolymer having the above-mentioned preferable properties, and as a result, the melt index and the pentad fraction were within specific ranges, and It has been found that a propylene homopolymer that satisfies a specific formula with respect to the relationship between the isotactic index and the pentad fraction and the relationship between the melting point and the enthalpy of fusion can meet the purpose.
The present invention has been completed based on such findings.
That is, according to the present invention, (1) the melt index is 0.8
(5) The pentad fraction f _mmmm obtained by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) using isotope carbon is 86.2 to 92 mol%.
(3) The relationship between the isotactic index (the amount of boiling n-heptane insoluble components) W (% by weight) and f _mmmm satisfies the formula: W <0.35 × f _mmmm +65, and (4) the melting point Tm The present invention provides a propylene homopolymer characterized in that the relationship between (° C.) and the enthalpy of fusion ΔH (J / g) satisfies the formula: Tm> 0.5 × ΔH + 113.

[0005] The propylene homopolymer of the present invention must have the following properties. First, (1) the melt index (MI) needs to be in the range of 0.8 to 5 g / 10 minutes. If the MI is less than 0.8 / 10 minutes, the discharge amount during molding is significantly reduced, and the productivity is poor.
When it exceeds g / 10 minutes, when a biaxially stretched film is formed, the uniformity of the thickness of the stretched film is reduced. In terms of productivity and uniformity of the thickness of the film after stretching, MI
Is preferably 0.8 to 4.5 g / 10 min, more preferably 1 to 4 g / 10 min. Note that this MI is
Based on JIS K-7210, temperature 230 ° C, load 2.
This is a value measured under the condition of 16 kg.

(2) The pentad fraction f _mmmm determined by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) using isotope carbon must be in the range of 86.2 to 92 mol%. When the pentad fraction is less than 86.2 mol%, when forming a biaxially stretched film, it adheres to a longitudinal stretching roll and is difficult to form, and when it exceeds 92 mol%, surface functionalities such as antistatic performance are reduced. A good film cannot be obtained, and the stress at the time of transverse stretching is high, so that the film is easily broken. In addition, this pentad fraction is referred to as "Macromolecule
s) ", ¹³ C-NMR [JNM E manufactured by JEOL Ltd.] according to the method described in Vol. 8, page 687 (1975).
X-400] at 400 MHz.

Next, (3) the isotactic index, that is, the amount W (% by weight) of the boiling n-heptane-insoluble component and f _mmmm
Is required to satisfy the relationship of W <0.35 × f _mmmm +65. If the value of this W is (0.
Above 35 × f _mmmm +65), the amount of the atactic polypropylene (APP) component that does not crystallize is small, and the additive does not easily precipitate on the film surface, so that surface functionality such as antistatic performance is not sufficiently exhibited. In addition, as the crystallinity increases, the stretchability and the transparency decrease. The isotactic index W is a value expressed by a weight fraction of an extraction residue (boiling n-heptane insoluble component amount) after extraction with boiling n-heptane for 6 hours using a Soxhlet extraction tester.

(4) The relationship between the melting point Tm (° C.) and the enthalpy of fusion ΔH (J / g) needs to satisfy the following equation: Tm> 0.5 × ΔH + 113. The ΔH is a measure of crystallinity, and when the crystallinity is reduced by copolymerization with ethylene, the melting point is significantly reduced and the heat resistance is reduced.
When the crystallinity is reduced by atactic polypropylene, the melting point does not decrease much. The Tm is (0.5 × ΔH +
113) Below, when a biaxially stretched film is produced,
Its heat resistance is insufficient. The melting point Tm and the melting enthalpy ΔH were measured using a differential scanning calorimeter (DSC-7 manufactured by PerkinElmer) at 250 ° C. for 3 minutes, and then cooled to 0 ° C. at a rate of 10 ° C./min. Further, the melting peak temperature when heating from 0 ° C. to 200 ° C. at a heating rate of 10 ° C./min is defined as melting point Tm, and 50 to 180 ° C.
Is the value obtained as the melting enthalpy ΔH.

The method for producing the propylene homopolymer of the present invention is not particularly limited as long as a propylene homopolymer satisfying the above requirements can be obtained, and various methods can be used. For example, (a) (a) a solid catalyst component composed of magnesium, titanium, a halogen atom and an electron donor, and (b) a solid component composed of a crystalline polyolefin used as necessary, and (b) an organoaluminum A compound and optionally used (c)
It can be produced by homopolymerizing propylene in the presence of a catalyst system comprising an electron donating compound.

The solid component (a) comprises a solid catalyst component (a) composed of magnesium, titanium, a halogen atom and an electron donor, and a crystalline polyolefin (b) used as required. Have been. The solid catalyst component of the component (a) is magnesium, titanium,
It contains a halogen atom and an electron donor as essential components, and can be prepared by contacting a magnesium compound, a titanium compound, and an electron donor. In this case, the halogen atom is contained as a halide in a magnesium compound and / or a titanium compound.

As the magnesium compound, for example,
Magnesium dihalide such as magnesium chloride,
Magnesium oxide, magnesium hydroxide, hydrotalcite, carboxylate of magnesium, alkoxymagnesium such as diethoxymagnesium, allyloxymagnesium, alkoxymagnesium halide, allyloxymagnesium halide, alkylmagnesium such as ethylbutylmagnesium, alkylmagnesium halide, Alternatively, a reaction product of an organomagnesium compound and an electron donor, a halosilane, an alkoxysilane, a silanol, an aluminum compound, and the like can be given. Of these, magnesium halide, alkoxymagnesium, alkylmagnesium, and alkylmagnesium halide are preferable. is there. Further, these magnesium compounds may be used alone or in combination of two or more.

Further, as the magnesium compound, a reaction product of metallic magnesium, a halogen and an alcohol can be used. The metal magnesium used at this time is not particularly limited, and metal magnesium of an arbitrary particle size,
For example, granules, ribbons, powders, and the like can be used. Also, the surface condition of metallic magnesium,
Although there is no particular limitation, it is preferable that a film such as magnesium oxide is not formed on the surface. Further, any alcohol can be used, but a lower alcohol having 1 to 6 carbon atoms is preferably used.Ethanol is particularly preferable because it gives a solid catalyst component which significantly improves the expression of catalytic performance. is there. The purity and water content of the alcohol are not limited, but if an alcohol having a high water content is used, magnesium hydroxide is formed on the surface of the metal magnesium, so that the water content is 1% by weight or less, especially 2,000.
It is preferable to use an alcohol of not more than ppm, and the lower the water content, the more advantageous.

The type of halogen and / or halogen-containing compound is not limited, and any halogen-containing compound can be used as long as it contains a halogen atom in its molecule. In this case, the type of the halogen atom is not particularly limited, but may be chlorine, bromine or iodine,
In particular, iodine is preferably used. Among the halogen-containing compounds, halogen-containing metal compounds are particularly preferred. The state, shape, particle size, and the like are not particularly limited, and may be arbitrary. For example, they can be used in the form of a solution in an alcohol-based solvent (for example, ethanol). The amount of alcohol used is 2 to 10 with respect to 1 mole of metallic magnesium.
0 mol, preferably in the range of 5 to 50 mol. If the amount of alcohol is too large, it tends to be difficult to obtain a magnesium compound having good morphology. If the amount is small, the reaction with metallic magnesium may not be performed smoothly.

The halogen and / or halogen-containing compound is usually 0.0001 g atoms or more, preferably 0.0005 g atoms or more, more preferably 0.000 g atoms or more as halogen atoms per 1 g of magnesium metal.
Used in proportions of 1 gram atom or more. If it is less than 0.0001 g atom, when the obtained magnesium compound is used without pulverization, the supported amount, the activity, the stereoregularity, the morphology of the produced polymer and the like are reduced, and the pulverization treatment becomes indispensable, which is not preferable. The particle size of the obtained magnesium compound can be arbitrarily controlled by appropriately selecting the amount of the halogen and / or the halogen-containing compound to be used.

The reaction of the metal magnesium with the alcohol and the halogen and / or the halogen-containing compound can be carried out by a known method. For example, this is a method in which a desired magnesium compound is obtained by reacting a metal magnesium, an alcohol, a halogen and / or a halogen-containing compound under reflux until the generation of hydrogen gas is no longer observed, usually for about 20 to 30 hours. Specifically, for example, when iodine is used as a halogen, a method in which metal magnesium and solid iodine are charged into an alcohol and then heated and refluxed, and an alcohol solution of the metal magnesium and iodine is dripped into the alcohol A method of post-heating and refluxing, a method of dropping an alcohol solution of iodine while heating an alcohol solution containing metallic magnesium, and the like can be given. Both methods include, for example, nitrogen gas,
It is preferable to carry out the reaction under an atmosphere of an inert gas such as an argon gas and optionally using an inert organic solvent (for example, a saturated hydrocarbon such as n-hexane). Regarding the charging of the metal magnesium, the alcohol, the halogen and / or the halogen-containing compound, it is not necessary to put all the respective amounts into the reaction tank from the beginning, and they may be divided and charged. A particularly preferred form is a method in which the alcohol is charged in its entirety from the beginning, and the magnesium metal is divided and charged several times.

In this case, it is possible to prevent a temporary large amount of hydrogen gas from being generated, which is very desirable in terms of safety. Also, the size of the reaction tank can be reduced. Furthermore, it is also possible to prevent entrainment of alcohol, halogen, and / or a halogen-containing compound caused by temporary mass generation of hydrogen gas. The number of splits is
It may be determined in consideration of the scale of the reaction tank, and usually 5 to 10 times is preferable in view of the complexity of the operation. Needless to say, the reaction itself may be of a batch type or a continuous type. Furthermore, as a variant, the operation of first adding a small amount of metallic magnesium to the alcohol which was initially charged in its entirety, separating and removing the product generated by the reaction in another tank, and then introducing a small amount of metallic magnesium again. It is also possible to repeat. When the magnesium compound thus obtained is used for the preparation of the next solid catalyst component, a dried one may be used, or a magnesium compound which has been filtered and washed with an inert solvent such as heptane may be used. In any case, the obtained magnesium compound can be used in the next step without pulverization or classification operation for uniforming the particle size distribution.

Further, as the titanium compound, for example,
Tetraalkoxytitanium such as tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetraisobutoxytitanium, tetracyclohexyloxytitanium, tetraphenoxytitanium, titanium tetrachloride, Titanium tetrahalides such as titanium tetrabromide and titanium tetraiodide, alkoxytitanium halides such as methoxytitanium trichloride, ethoxytitanium trichloride, propoxytitanium trichloride, n-butoxytitanium trichloride and ethoxytitanium tribromide, dimethoxy Titanium dichloride, diethoxytitanium dichloride, dipropoxytitanium dichloride, di-n-butoxytitanium dichloride, diethoxytitanium Monohalogenated trialkoxytitaniums such as dihalogenated dialkoxytitanium such as bromide, trimethoxytitanium chloride, triethoxytitanium chloride, tripropoxytitanium chloride and tri-n-butoxytitanium chloride may be mentioned. Halogen-containing titanium compounds,
Particularly, titanium tetrachloride is preferable. These titanium compounds may be used alone or in combination of two or more.

Then, as an electron donor, (c)
Those exemplified as the electron donating compound of the component can be used. The preparation of the solid catalyst component (a) is carried out by a known method (JP-A-53-43094, JP-A-55-13).
No. 5102, JP-A-55-135103, JP-A-56-18606, JP-A-56-16620
No. 5, JP-A-57-63309, JP-A-57-63309
-190004, JP-A-57-300407, and JP-A-58-47003).

The composition of the solid catalyst component (a) thus prepared usually has a magnesium / titanium atomic ratio of 2
-100, the halogen / titanium atomic ratio is 5-100, and the electron donor / titanium molar ratio is in the range of 0.1-10. Examples of the crystalline polyolefin (b) used as necessary in the preparation of the solid component (a) include those having 2 to 10 carbon atoms such as polyethylene, polypropylene, polybutene, and poly-4-methyl-1-pentene. Α-
And crystalline polyolefins obtained from olefins. This crystalline polyolefin is (1) the above (a)
A method in which propylene is prepolymerized in the presence of a combination of a solid catalyst component, an organoaluminum compound and an electron donating compound used as required (preliminary polymerization method); (2) crystalline polyethylene having a uniform particle size (3) a method of dispersing the solid catalyst component, the organoaluminum compound used as required, and the electron-donating compound (having a melting point of 100 ° C. or higher) in a crystalline powder such as polypropylene or polypropylene (dispersion method); It can be obtained by using a method such as a combination of the method (1) and the method (2).

In the prepolymerization method (1), the aluminum / titanium atomic ratio is usually selected from the range of 0.1 to 100, preferably 0.5 to 5, and the molar ratio of the electron donating compound / titanium is selected. It is selected in the range of 0 to 50, preferably 0.1 to 2. Regarding the ratio of (a) the solid catalyst component and (b) the crystalline polyolefin in the (a) solid component,
The weight ratio of the component (b) to the component (a) is usually 0.03.
To 200, preferably 0.10 to 50.

Next, as the organoaluminum compound used as the component (b), a compound represented by the following general formula (I): AlR ¹ _p X _3-p (I) wherein R ¹ is a group having 3 to 20 carbon atoms An alkyl group or an aryl group having 6 to 20 carbon atoms, X is a halogen atom, and p is 1 to 3
Indicates the number of ] Can be mentioned. For example, triisopropylaluminum, triisobutylaluminum, trialkylaluminum such as trioctylaluminum, diethylaluminum monochloride, diisopropylaluminum monochloride,
Dialkylaluminum monohalides such as diisobutylaluminum monochloride and dioctylaluminum monochloride, and alkylaluminum sesquihalides such as ethylaluminum sesquichloride can be suitably used. These aluminum compounds may be used alone or in combination of two or more.

Further, in the catalyst, an electron donating compound is used as a component (c) if necessary. The electron donating compound is a compound containing oxygen, nitrogen, phosphorus, sulfur, silicon, and the like. Basically, a compound having a performance of improving regularity in propylene polymerization is considered.
Such electron donating compounds include, for example, organosilicon compounds, esters, thioesters, amines,
Ketones, nitriles, phosphines, ethers, thioethers, acid anhydrides, acid halides, acid amides,
Examples include aldehydes, organic acids, and azo compounds.

For example, diphenyldimethoxysilane, diphenyldiethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, t-butyl-n-propyldimethoxysilane, dibenzyldimethoxysilane,
Organosilicon compounds such as tetramethoxysilane, tetraethoxysilane, tetraphenoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriphenoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, benzyltrimethoxysilane, monomethylphthalate, Monoethyl phthalate, monopropyl phthalate, monobutyl phthalate, monoisobutyl phthalate, monoamyl phthalate, monoisoamyl phthalate, monomethyl terephthalate, monoethyl terephthalate, monopropyl terephthalate, monobutyl terephthalate, monoisobutyl terephthalate, dimethyl phthalate, diethyl phthalate, diethyl phthalate, di Propyl phthalate, dibutyl phthalate, diisobutyl phthalate, diami Phthalate, diisoamyl phthalate, methyl ethyl phthalate, methyl isobutyl phthalate, methyl propyl phthalate, ethyl butyl phthalate, ethyl isobutyl phthalate, ethyl propyl phthalate, propyl isobutyl phthalate, dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, diisobutyl terephthalate, methyl ethyl terephthalate , Methyl isobutyl terephthalate, methyl propyl terephthalate, ethyl butyl terephthalate, ethyl isobutyl terephthalate, ethyl propyl terephthalate, propyl isobutyl terephthalate, dimethyl isophthalate, diethyl isophthalate, dipropyl isophthalate, diisobutyl isophthalate, methyl ethyl isophthalate , Methyl isobutyl isophthalate, methyl propyl isophthalate,
Aromatic dicarboxylic acid esters such as ethyl butyl isophthalate, ethyl isobutyl isophthalate, ethyl propyl isophthalate, propyl isobutyl isophthalate, methyl formate, ethyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate , Ethyl propionate, methyl butyrate, ethyl butyrate, ethyl valerate, methyl chloroacetate, ethyl dichloroacetate, methyl methacrylate, ethyl crotonate, ethyl bivalate, dimethyl maleate, ethyl cyclohexanecarboxylate, methyl benzoate, benzoic acid ethyl,
Propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate,
Amyl toluate, ethyl ethyl benzoate, methyl anisate, ethyl anisate, ethyl ethoxy benzoate, p-
Ethyl butoxybenzoate, ethyl o-chlorobenzoate,
Monoesters such as ethyl naphthoate, esters such as γ-butyrolactone, δ-valerolactone, coumarin, phthalide, ethylene carbonate, organic acids such as benzoic acid and p-oxybenzoic acid, succinic anhydride, benzoic anhydride, and anhydride Acid anhydrides such as p-toluic acid, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, benzoquinone, aldehydes such as acetaldehyde, propionaldehyde, octylaldehyde, tolualdehyde, benzaldede, naphthyl aldehyde, and acetyl chloride , Acetyl bromide, propionyl chloride, butyryl chloride, isobutyryl chloride, 2-methylpropionyl chloride, valeryl chloride, isovaleryl chloride, hexanoyl chloride, Methylhexanoyl chloride, 2
-Ethylhexanoyl chloride, octanoyl chloride, decanoyl chloride, undecanoyl chloride, hexadecanoyl chloride, octadecanoyl chloride,
Hensyl carbonyl chloride, dichlorohexane carbonyl chloride, malonyl dichloride, succinyl dichloride, pentanedioleyl dichloride, hexanedioleyl dichloride, dichlorohexane dicarbonyl dichloride, benzoyl chloride, benzoyl bromide, methyl benzoyl chloride, phthaloyl chloride, isophthaloyl chloride , Terephthaloyl chloride, benzene-
Acid halides such as 1,2,4-tricarbonyl trichloride, methyl ether, ethyl ether, isopropyl ether, n-butyl ether, isopropyl methyl ether, isopropyl ethyl ether, t-butyl ethyl ether, t-butyl-n- Ethers such as propyl ether, t-butyl-n-butyl ether, t-amyl methyl ether, t-amyl ethyl ether, amyl ether, tetrahydrofuran, anisole, diphenyl ether, ethylene glycol butyl ether, acetate amide, benzoic acid amide, toluic acid amide Acid amides such as tributylamine, N, N'-dimethylpiperazine, tribenzylamine, aniline, pyridine, pyrroline, amines such as tetramethylethylenediamine, acetonitrile Nitriles such as ril, benzonitrile and tolunitrile, 2,2'-azobis (2-methylpropane), 2,2'-azobis (2-ethylpropane), 2,2'-azobis (2-methylpentane) And an azo compound in which a sterically hindered substituent is bonded to the azo bond.

Of these, organosilicon compounds, esters, ketones, ethers, thioethers, acid anhydrides, and acid halides are preferred. Particularly, diphenyldimethoxysilane, cyclohexyldimethoxysilane, dicyclopentyldimethoxysilane, and t- Organosilicon compounds such as butyl-n-propyldimethoxysilane, di-n-
Preferred are diesters of aromatic dicarboxylic acids such as butyl phthalate and diisobutyl phthalate, and alkyl esters of aromatic monocarboxylic acids such as benzoic acid, p-methoxybenzoic acid, p-ethoxybenzoic acid, and toluic acid. These electron donating compounds may be used alone or in combination of two or more.

Regarding the amount of each component of the catalyst system,
(A) The amount of the solid component is usually in the range of 0.0005 to 1 mol per liter of reaction volume in terms of titanium atom. (B) The organoaluminum compound usually has an aluminum / titanium atom ratio of 1 to 3.0.
00, preferably 40 to 800, and if the amount is outside the above range, the catalytic activity may be insufficient.

The type of polymerization is not particularly limited, and methods such as slurry polymerization, gas phase polymerization, bulk polymerization, and solution polymerization can be used. In the present invention, gas phase polymerization is particularly preferred. A process such as a conventional slurry polymerization method is not preferable because an atactic polypropylene component useful for the use of the biaxially oriented polypropylene film may be removed. Regarding the polymerization conditions when performing polymerization by gas phase polymerization, the polymerization pressure is usually 10 to 45 kg / cm ² G, preferably 20 to 30 kg.
/ Cm ² G, and the polymerization temperature is appropriately selected in the range of usually 40 to 90 ° C, preferably 60 to 75 ° C. The molecular weight of the polymer can be adjusted by known means, for example, by adjusting the hydrogen concentration in the polymerization vessel. The polymerization time depends on the reaction temperature and cannot be determined unconditionally.
Minutes to 10 hours are sufficient.

In the polymerization, the components constituting the catalyst system, that is, the components (a) to (c) are mixed at a predetermined ratio and brought into contact with each other.
The polymerization may be started, or the monomer may be introduced after aging for about 0.2 to 3 hours after the contact. Further, this catalyst component can be supplied by suspending in an inert solvent, an olefin or the like. In the present invention, post-treatment after polymerization can be carried out by a conventional method. That is, in the gas phase polymerization method, after polymerization, the polymer powder derived from the polymerization vessel may be passed through a nitrogen gas stream or the like in order to remove monomers and the like contained therein. If desired, pelletization may be performed by an extruder. At that time, a small amount of water, alcohol, or the like may be added to completely deactivate the catalyst. In the bulk polymerization method, after polymerization, the monomer can be completely separated from the polymer led out of the polymerization vessel and then pelletized.

The propylene homopolymer of the present invention is particularly suitably used as a base resin for a biaxially oriented polypropylene film. When making a biaxially stretched film, first,
If necessary, various known additives such as antioxidants, weathering agents, heat stabilizers, antistatic agents, antifogging agents, antiblocking agents, neutralizing agents, lubricants, nucleating agents may be added to the propylene homopolymer. , A coloring agent, an inorganic or organic filler, etc., and mixing with a tumbler blender, Henschel mixer, etc., or after mixing, further melt-kneading and granulating using a single screw extruder or a multi-screw extruder, or a kneader A polypropylene resin composition is prepared by melt-kneading and granulating with a Banbury mixer or the like.

Next, this polypropylene resin composition is
For example, a sheet is formed by extruding from a T-die using an extruder. The resin temperature at this time is usually 220 to 300
° C, preferably 240-280 ° C. Next, the sheet is usually heated at 110 to 160 ° C., preferably 130 to 160 ° C.
After stretching in the machine direction at a temperature of 150 ° C. and a stretching ratio of about 3 to 7 times, usually 130 to 170 ° C., preferably 1 to
At a temperature of 45 to 165 ° C., the film is stretched in the transverse direction at a stretch ratio of about 7 to 12 times to produce a biaxially stretched polypropylene film. The thickness of the biaxially stretched polypropylene film thus obtained is usually in the range of 5 to 100 μm. The film may be subjected to a surface treatment such as a corona discharge treatment if desired.

[0030]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, MI of polypropylene resin,
The pentad fraction f _mmmm , the isotactic index W, the melting point Tm, and the melting enthalpy ΔH were measured according to the methods described above. The physical properties of the film were determined in the following manner. (1) Lateral stretching load This indicates the yield load when transverse stretching is performed with a table tenter. (2) Haze value Haze value was measured in accordance with JIS K-7105. (3) Tensile modulus Measured in accordance with JIS K-113. (4) Surface specific resistance It was measured using a static honest meter manufactured by Shishido Shosha.

Example 1 (Reference Example) (1) Preparation of Magnesium Compound After a glass reactor equipped with a stirrer having an inner volume of 12 liters was sufficiently replaced with nitrogen gas, about 4,860 ethanol was added.
g, 32 g of iodine and 320 g of metallic magnesium were reacted under reflux with stirring to obtain a solid reaction product. The reaction liquid containing the solid reaction product was dried under reduced pressure to obtain a magnesium compound (solid product). (2) Preparation of solid catalyst component 160 g of the magnesium compound (not pulverized) obtained in the above (1) and purified heptane 800 were placed in a 5-liter glass three-necked flask sufficiently purged with nitrogen gas. Milliliter, 24 milliliters of silicon tetrachloride and 23 milliliters of diethyl phthalate were added. 9 in the system
After maintaining the temperature at 0 ° C. and stirring, 770 ml of titanium tetrachloride was added thereto and reacted at 110 ° C. for 2 hours. Then, a solid component was separated and washed with purified heptane at 80 ° C. Further, 1,220 ml of titanium tetrachloride was added, and 110
After reacting at 2 ° C. for 2 hours, it was sufficiently washed with purified heptane to obtain a solid catalyst component.

(3) Pre-polymerization treatment 230 liters of n-heptane was charged into a 500 liter reactor with stirring blades, and 25 kg of the solid catalyst component obtained in the above (2) was added. After adding 0.6 mol of triethylaluminum and 0.4 mol of cyclohexylmethyldimethoxysilane per 1 g of Ti in the solid catalyst component, propylene is added until the partial pressure of propylene reaches 0.3 kg / cm ² G. Introduce 2
The reaction was performed at 0 ° C. for 4 hours. After completion of the reaction, the solid catalyst component was washed several times with n-heptane, carbon dioxide was supplied, and the mixture was stirred for 24 hours. (4) Polymerization of Propylene The treated solid catalyst component of the above (3) was converted into Ti
Triethyl aluminum was supplied at a rate of 0.37 mmol / hr at a mmol / hr, and the reaction was carried out at a polymerization temperature of 80 ° C. and a propylene pressure of 28 kg / cm ² G. On this occasion,
Hydrogen gas was supplied so as to have a predetermined molecular weight. The properties of the polypropylene resin thus obtained are shown in Table 1.

(5) Preparation of Biaxially Stretched Film The phenolic antioxidant, the phosphorous antioxidant 1,500 ppm, and the calcium stearate (1,000 ppm) were added to the polypropylene resin obtained in the above (4) on a weight basis. 1,500 ppm of a neutralizing agent), 2,500 ppm of a silica-based antiblocking agent, and 5,000 ppm of a combination of an ethylene oxide adduct of a higher amine and a fatty acid monoglyceride (antistatic agent), and 2FC manufactured by Kobe Steel Co., Ltd.
Granulation was performed at a resin temperature of 220 ° C. using an M continuous kneading granulator to prepare a polypropylene resin composition. Next, using a 35 mmφ sheet molding machine manufactured by Shinko Kikai Seisakusho, the resin composition was heated at 260 ° C. and chill roll temperature at 30 ° C.
After the sheet was formed under the following conditions, the sheet was longitudinally stretched by a roll stretching machine manufactured by Iwamoto Seisakusho at a stretching temperature of 145 ° C. and a draw ratio of 5 times, and then stretched by a table tenter manufactured by Iwamoto Seisakusho at a temperature of 164. ℃, preheating time:
The film was transversely stretched under the conditions of 80 seconds, a stretching speed of 90% / second, and a stretching ratio of 10 times, to produce a biaxially stretched film having a thickness of 25 μm. Subsequently, the biaxially stretched film was subjected to a surface treatment using a roll electrode type corona discharge treatment machine manufactured by Kasuga Electric Co., Ltd. The wettability of the treated surface was 42 dyne / cm.
Table 1 shows the physical properties of the biaxially stretched film.

Example 2 In Example 1- (4), cyclohexylmethyldimethoxysilane was used as a stereoregularity improver in an amount of 1.5 mmol / mol.
A polypropylene resin was produced in the same manner as in Example 1, except that the resin was supplied at the same time, and a biaxially stretched film was produced. The results are shown in Table 1.

Example 3 In Example 1- (4), 0.75 mmol / h of dicyclopentyldimethoxysilane was used as a stereoregularity improver.
A polypropylene resin was produced in the same manner as in Example 1 except that the resin was supplied at r, and a biaxially stretched film was produced. The results are shown in Table 1.

Comparative Example 1 In Example 1- (4), cyclohexylmethyldimethoxysilane was used as a stereoregularity improver at 3.5 mmol / mol.
A polypropylene resin was produced in the same manner as in Example 1, except that the resin was supplied at the same time, and a biaxially stretched film was produced. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2 In a polymerization tank having an internal volume of 200 liters and equipped with a stirring blade, n-heptane was 11.5 liter / hr, titanium trichloride was 4.5 g / hr as a catalyst, and diethyl aluminum chloride was 5.4.
g / hr, the temperature is 70 ° C., and the pressure is 7.0 k.
Slurry polymerization was carried out by supplying propylene so as to maintain g / cm ² G. At this time, hydrogen gas was supplied so as to have a predetermined molecular weight. The polymerization slurry was continuously withdrawn into 40 liters of n-heptane containing 6 liters of butanol, subjected to batchwise demonomerization and catalyst removal at 65 ° C., and subjected to solid-liquid separation by a centrifugal separator. −
After washing with heptane and drying, a polypropylene resin was obtained. Next, a biaxially stretched film was produced in the same manner as in Example 1. The results are shown in Table 1.

[0038]

[Table 1]

[0039]

[Table 2]

Comparative Example 3 In Example 1- (4), cyclohexylmethyldimethoxysilane was used as a stereoregularity improver in an amount of 95 mmol / mol.
A propylene-ethylene copolymer was produced in the same manner as in Example 1, except that the mixture was supplied at a rate of hr and ethylene was supplied so as to have a predetermined ethylene unit content. This copolymer has an ethylene unit content of 1.8 mol% and an MI of
The melting point was 149 ° C., the enthalpy of fusion was 86 J / g, and the parameter 2 was 156. Also,
Using this copolymer, an attempt was made to produce a biaxially stretched film in the same manner as in Example 1, but the film could not be stretched because of its low melting point.

[0041]

EFFECT OF THE INVENTION The propylene homopolymer of the present invention has the biaxially oriented polypropylene film which retains the heat resistance characteristic of a biaxially oriented polypropylene film and has improved surface functions such as stretchability, transparency and antistatic performance. A polypropylene film can be provided.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI // B29K 23:00 B29L 7:00 C08L 23:12 (56) References JP-A-2-180906 (JP, A) JP-A-8- 73529 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 110/06 B29C 55/12 C08F 2/34 C08F 4/652 C08J 5/18

Claims (5)

(57) [Claims] (1) The melt index is 0.8 to 5 g.
/ 10 minutes, (2) the pentad fraction f _mmmm determined by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) using isotope carbon is 86.2 to 92 mol%, and (3) isotactic. Index (boiling n-heptane insoluble component amount) W
(Weight%) and f _mmmm satisfy the formula: W <0.35 × f _mmmm +65, and (4) the relationship between melting point Tm (° C.) and enthalpy of fusion ΔH (J / g) A propylene homopolymer, which satisfies the formula: Tm> 0.5 × ΔH + 113. 2. The propylene homopolymer according to claim 1, which is obtained by a gas phase polymerization method. 3. The propylene homopolymer according to claim 1, which is used as a base resin of a biaxially stretched polypropylene film. 4. A biaxially stretched polypropylene film obtained by forming and stretching the propylene homopolymer according to claim 1. 5. The propylene alone according to claim 1 or 2
Antistatic biaxially stretched polyp formed by forming and stretching a polymer
Lopylene film.