JP3139525B2 - Propylene homopolymer and 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 a stretched film using the same.
The present invention relates to a propylene homopolymer which provides a biaxially oriented polypropylene film having improved rigidity, heat resistance and transparency without impairing stretch formability, and a film obtained by forming and stretching the same.

[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, the biaxially stretched polypropylene film has characteristics such as excellent heat resistance, tensile strength, impact strength, gas permeability, and stiffness. However, in the biaxially stretched polypropylene film, as the stereoregularity is increased, the crystallinity and orientation are significantly increased, so that the film properties such as rigidity are improved, but the stress at the time of stretching is increased. As a result, there is a problem in molding such as breakage of stretching. Therefore, a technique for improving the film properties such as rigidity without impairing the stretchability has been desired. A method of improving the rigidity of the film using polypropylene having high stereoregularity has been proposed (Japanese Patent Publication No.
No. -48926, Japanese Patent Publication No. 4-28727),
In this method, the stretchability is not sufficiently improved. As a method for improving the stretchability using a catalyst system having a high stereoregularity, a random copolymerization of propylene and ethylene is known (Japanese Patent Publication No. 4-22923).
In such copolymerization with ethylene, the melting point is lowered, so that there is a problem that the heat resistance characteristic of the biaxially stretched polypropylene film is inevitably impaired.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a propylene homopolymer which provides a biaxially oriented polypropylene film having improved rigidity, heat resistance and transparency without impairing stretch formability under such circumstances. And film-forming this,
It is intended to provide a stretched film obtained by stretching.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a propylene homopolymer having a specific property can achieve the object. . The present invention has been completed based on such findings. That is, the present invention provides (1) a melt index of 0.5 to 5 g / 10 minutes,
(2) Nuclear magnetic resonance spectroscopy with isotope carbon ( ¹³ C-NM
Pentad fraction f _mmmm obtained by R) is 92-9
8 mol% (excluding 92 mol%) ,
(3) The melting enthalpy ΔH measured by a differential scanning calorimeter (DSC) is 98 J / g or more. (4) The relaxation time τ at which the angular frequency ω obtained from the melt viscoelasticity measurement is 10 ⁻¹ / sec is it 3sec or less, and (5) retention of 'the elastic modulus at 120 ° C. for ₍₂₃ (E elastic modulus at 23 ° C. obtained from a solid viscoelasticity measurement E)' ₁₂₀₎ (E _'120 /
E ′ ₂₃ × 100) is 14% or more.

[0005] The propylene homopolymer of the present invention has the following properties. First, (1) melt index (M
It is necessary that I) is in the range of 0.5 to 5 g / 10 minutes. When the MI is less than 0.5 / 10 minutes, the discharge amount during molding is significantly reduced and productivity is poor. When the MI exceeds 5 g / 10 minutes, when a biaxially stretched film is formed, the stretched film The uniformity of the thickness is reduced. From the viewpoint of productivity and uniformity of the thickness of the film after stretching, a preferable range of MI is
0.8 to 4.5 g / 10 min, more preferably 1 to 4 g
/ 10 minutes. In addition, this MI is JIS K-72
It is a value measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with No. 10.

(2) The pentad fraction f _mmmm determined by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) using isotope carbon is 92 to 98 mol% (excluding 92 mol%).
Must be in the range of When the pentad fraction is less than 92 mol%, the rigidity of the obtained film is insufficient, and when it exceeds 98 mol%, the stress at the time of transverse stretching becomes high and stretching breaks easily occur. In addition, this pentad fraction is referred to as “Macromolecules (Macromolec).
ules), Vol. 8, p. 687 (1975), using ¹³ C-NMR [JN manufactured by JEOL Ltd.
M EX-400] at 400 MHz.

Next, (3) Differential scanning calorimeter (DSC)
Is required to be 98 J / g or more. When this ΔH is less than 98 J / g,
The rigidity of the obtained film is insufficient due to low crystallinity. The melting enthalpy ΔH was measured using DSC-7 manufactured by Perkin Elmer Co., Ltd. at 250 ° C. for 3 minutes, then cooled to 0 ° C. at a rate of 10 ° C./min, and further increased from 0 ° C. to 200 ° C. It is a value indicated by the heat of fusion at 50 to 180 ° C. when heated at 10 ° C./min.

(4) The relaxation time τ at which the angular frequency ω obtained from the melt viscoelasticity measurement is 10 ⁻¹ / sec is 3 sec.
It must be: This relaxation time τ is 3
If it exceeds c, the stretchability decreases. The relaxation time τ was determined by using a system-4 manufactured by Rheometrics Inc. (rotary rheometer, cone plate (25 mmφ), cone angle: 0.1 radian) at a temperature of 170 ° C. and an angular frequency ω = 10 ⁻¹ / sec. , A sinusoidal shear strain is applied, and from the storage modulus G ^′ and the loss modulus G ^″ , the relational expression τ
= G ^′ / ωG ^″ .

Finally, (5) the retention (E ' ₁₂₀ / E' ₂₃ ) of the elastic modulus (E ' ₁₂₀ ) at 120 ° C. with respect to the elastic modulus (E' ₂₃ ) at 23 ° C. obtained from the solid viscoelasticity measurement. × 100),
It needs to be 14% or more. When the retention of the elastic modulus is less than 14%, the heat resistance of the obtained film is insufficient. Further, the retention of the elastic modulus is 14% as in the present invention.
In this case, the resulting film not only has high rigidity at room temperature, but also retains rigidity at high temperatures (at the time of heat sealing or at the time of steam sterilization in food packaging, at the time of heating of retort food), thereby suppressing shrinkage. Is done. From the viewpoint of heat resistance of the film, a preferable elastic modulus retention rate is 15% or more. The retention of the elastic modulus is determined by vi
Using a sco-elastic spectrometer, a press-formed sample having a thickness of 1 mm was subjected to a periodic strain of 10 Hz to obtain storage elastic moduli E ′ ₁₂₀ and E ′ ₂₃ at 120 ° C. and 23 ° C. (room temperature). ₁₂₀ / E _'23 × 100
It is a value represented by.

Since the propylene homopolymer of the present invention has a high stereoregularity, the use of a polymer having a high crystallinity and a high melting point improves the rigidity and heat resistance of the obtained film and has a low molecular weight component. (Narrow molecular weight distribution)
Therefore, by using a material that is easy to relax, the lateral stretchability is improved. 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 required, and (b)
It can be produced by homopolymerizing propylene in the presence of a catalyst system comprising an organoaluminum compound and a commonly used (c) electron donating compound.

The solid component (a) comprises (a) a solid catalyst component composed of magnesium, titanium, a halogen atom and an electron donor, and (b) a crystalline polyolefin used as necessary. 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.

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 having an arbitrary particle size, for example, a granular, ribbon-like, powder-like or the like can be used. The surface state of the metallic magnesium is not particularly limited, but it is preferable that the surface of the metallic magnesium is not coated with magnesium oxide or the like. Further, any alcohol can be used, but the alcohol has 1 to 1 carbon atoms.
It is preferable to use the lower alcohol of No. 6, and ethanol is particularly preferable since it gives a solid catalyst component which significantly improves the expression of the catalytic performance. The purity and water content of the alcohol are not limited. However, when 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, particularly 2000 ppm.
The following alcohols are preferably used, and the lower the water content, the more advantageous.

There is no limitation on the type of halogen and / or halogen-containing compound, and any compound containing a halogen atom in its molecule can be used as the halogen-containing compound. In this case, the kind of the halogen atom is not particularly limited, but chlorine, bromine or iodine, particularly 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 100 with respect to 1 mole of metallic magnesium.
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 the halogen-containing compound are usually 0.0001 g atoms or more, preferably 0.1 g or more as halogen atoms per 1 g of metal magnesium.
It is used in a proportion of at least 0005 gram atoms, more preferably at least 0.001 gram atoms. 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. Further, by appropriately selecting the amount of the halogen and / or the halogen-containing compound to be used, the particle size of the obtained magnesium compound can be arbitrarily controlled.

The reaction itself between the metal magnesium, 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 using iodine as a halogen, after adding metal magnesium and solid iodine in alcohol, heating and refluxing, after dropwise adding an alcohol solution of metal magnesium and iodine in alcohol A method of 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 are preferably performed under an inert gas atmosphere such as a nitrogen gas or an argon gas, optionally using an inert organic solvent (for example, a saturated hydrocarbon such as n-hexane). Metal magnesium,
Regarding the charging of the alcohol, the halogen and / or the halogen-containing compound, it is not necessary to put the whole amount into the reaction tank from the beginning, and it may be divided and fed. 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. Further, these titanium compounds may be used alone or in combination of two or more.

As the 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 to 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. Also,
Examples of the crystalline polyolefin of the component (b) used as necessary in the preparation of the solid component (a) include:
Polyethylene, polypropylene, polybutene, poly 4-
A crystalline polyolefin obtained from an α-olefin having 2 to 10 carbon atoms such as methyl-1-pentene is exemplified. This crystalline polyolefin is prepared by (1) a method of pre-polymerizing propylene in the presence of (a) a combination of the solid catalyst component, an organoaluminum compound, and an electron-donating compound used as required (pre-polymerization method). ), (2) a crystalline powder such as crystalline polyethylene or polypropylene having a uniform particle size, the solid catalyst component (a), an organic aluminum compound and an electron-donating compound (melting point of 100 ° C. or higher) used as necessary. (Dispersion method), (3) a method of combining the above method (1) and the method (2), or the like.

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 donor compound / titanium is 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 component (b), the general formula (I) AlR in ^{_{1 p X 3-p ··· (}} I) [wherein, R ¹ represents 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, an electron donating compound is usually used as the component (c) in the catalyst. 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. Examples of such electron donating compounds include organosilicon compounds, esters, thioesters, amines, ketones, nitriles, phosphines, ethers, thioethers, acid anhydrides, acid halides, acid amides. , Aldehydes, organic acids, azo compounds and the like.

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, and 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. The (b) organoaluminum compound has an aluminum / titanium atom ratio of usually 1 to 30.
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 slurry polymerization, gas phase polymerization, bulk polymerization, solution polymerization and the like are used. 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 usually 4 kg / cm ² G.
It is appropriately selected within the range of 0 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, but about 5 minutes to 10 hours is 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, the catalyst component can be supplied by suspending in an inert solvent 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 present invention also provides a stretched film comprising the propylene homopolymer. The stretched film of the present invention may be a uniaxially stretched film or a biaxially stretched film, but a biaxially stretched film is particularly preferred. Next, a method for producing the biaxially stretched film will be described. First, if necessary, various known additives such as antioxidants, weathering agents, heat stabilizers, antistatic agents, antifogging agents, antiblocking agents, neutralizing agents, lubricants, lubricants, etc. are added to the propylene homopolymer. A nucleating agent, a colorant, an inorganic or organic filler, etc. are blended and mixed with a tumbler blender, a Henschel mixer, or the like, or after mixing, further melt-kneaded and granulated using a single-screw extruder or a multi-screw extruder.
Alternatively, a polypropylene resin composition is prepared by melt-kneading and granulating using a kneader, 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 oriented polypropylene film thus obtained is usually in the range of 5 to 100 μm. In the present invention, if necessary, the surface of the stretched film may be treated to increase the surface energy or polarize the surface. This surface treatment improves the adhesive strength in coating, laminating, printing and the like. This surface treatment method can be roughly classified into a surface oxidation method and a surface unevenness method. Examples of the surface oxidation method include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone and ultraviolet rays. Examples of the method include irradiation and the like, and examples of the method for making the surface uneven include a sand blast method and a solvent treatment method.

[0031]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The MI, pentad fraction f _mmmm , melting enthalpy ΔH, relaxation time τ, and elastic modulus retention (E ′ ₁₂₀ / E ′ ₂₃ × 100) of the polypropylene resin are as follows:
It was measured according to the method described above. The physical properties of the film were measured according to the following procedure. (1) Lateral stretching load Shown as the descending load when the sheet is laterally stretched with a table tenter. (2) Haze value Haze value was measured according to JIS K-7105. (3) Tensile modulus Measured according to JIS K-113.

Example 1 (1) Preparation of magnesium compound After a glass reactor equipped with a stirrer having an internal 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 charged and reacted under reflux conditions 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
While maintaining the temperature at 0 ° C., 770 ml of titanium tetrachloride was added thereto with stirring and reacted at 110 ° C. for 2 hours, the 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 reaction vessel equipped with a stirring blade, 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 In the polymerization tank having an internal volume of 200 liters with stirring blades, the treated solid catalyst component of the above (3) was converted into Ti atoms by 3
Of triethylaluminum at 0.37 mmol / hr and cyclohexylmethyldimethoxysilane at 95 mmol / hr.
The reaction was carried out at 0 ° C. and a propylene pressure of 28 kg / cm ² G. At this time, 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 Based on the polypropylene resin obtained in the above (4), 1,000 ppm of a phenolic antioxidant, 1,500 ppm of a phosphorus based antioxidant, and Combination of 1,500 ppm and 2,500 ppm of a silica-based antiblocking agent, 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, a sheet was formed from the above resin composition at a resin temperature of 260 ° C. and a chill roll temperature of 30 ° C. using a 35 mm φ sheet forming machine manufactured by Shinko Machinery Works. The film was stretched longitudinally at a temperature of 5 ° C. and a stretching ratio of 5 times, and then transversely stretched by a table tenter manufactured by Iwamoto Seisakusho under the conditions of a stretching temperature of 164 ° C., a preheating time of 80 seconds, a stretching speed of 90% / second and a stretching ratio of 10 times. And a biaxially stretched film having a thickness of 25 μm. Subsequently, the biaxially stretched film was subjected to a surface treatment with 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), except that cyclohexylmethyldimethoxysilane was supplied at 3.5 mmol / hr.
A polypropylene resin was produced in the same manner as in Example 1, and a biaxially stretched film was produced. The results are shown in Table 1.

Comparative Example 1 In Example 1- (4), except that cyclohexylmethyldimethoxysilane was supplied at 2.0 mmol / hr.
A polypropylene resin was produced in the same manner as in Example 1, and a biaxially stretched film was produced. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2 In a polymerization tank with a stirring blade having an internal volume of 200 liters, 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 65 ° C, and the pressure is 6.5k.
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]

(Note) *: Frequent stretching breaks **: Mw / Mn: weight average molecular weight / number average molecular weight. These values were obtained under the following conditions. That is,
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined by gel permeation chromatography (GPC method).
Was measured to determine the molecular weight distribution, that is, Mw / Mn. The measurement conditions are as follows. GPC column: Shodex UT-806M (two connected) Solvent: 1,2,4-trichlorobenzene Flow rate: 1.0 ml / min Sample concentration: 0.2% by weight Temperature: 145 ° C Calibration curve: Universal Caribrate
n (by polypropylene standard sample) Detector: RI (Waters 150C) Analysis: GRP-PRO (V3.12)

[0040]

Industrial Applicability The propylene homopolymer of the present invention can provide a biaxially oriented polypropylene film having improved rigidity, heat resistance and transparency without impairing stretch formability. It is suitably used as a base resin of the above.

────────────────────────────────────────────────── ─── of the front page continued (51) Int.Cl. ⁷ identification mark FI C08L 23:12 (56) reference Patent flat 8-73528 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) C08F 110/06 C08J 5/18 B29C 55/12

Claims (3)

(57) [Claims] 1. Melt index: 0.5 to 5 g
/ 10 minutes, and (2) the pentad fraction f _mmmm determined by nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) using isotope carbon is 92 to 98 mol% (however, excluding 92 mol%
It is continued), (3) differential scanning calorimeter (melting enthalpy ΔH as measured by DSC) is 98 J / g or more, (4) the angular frequency obtained from the melt viscoelasticity measurement ω is 10 ^-1 / the relaxation time τ in sec is 3 sec or less, and (5) the elastic modulus at 120 ° C. (E ′ ₁₂₀ ) with respect to the elastic modulus at 23 ° C. (E ′ ₂₃ ) obtained from solid viscoelasticity measurement.
Propylene homopolymer having a retention of (E ' ₁₂₀ / E' ₂₃ × 100) of 14% or more. 2. A stretched film obtained by film-forming and stretching the propylene homopolymer according to claim 1. 3. The stretched film according to claim 2, which is a biaxially stretched film.