JPH11254522A - Polypropylene film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polypropylene film high in the tensile modulus and tensile strength of a film in the flow direction thereof good in the balance the tensile modulus and tensile strength in the direction crossing the flow direction at a right angle and excellent in perspective properties. SOLUTION: The sum (MD orientation index +TD orientation index) of the MD orientation index in the flow direction of a film and the TD orientation index in the direction crossing the flow direction of the film at a right angle by an X-ray diffraction method is 0.6-1.1 and the ratio (MD orientation index/TD orientation index) of the MD orientation index and the TD orientation index is 0.3-0.9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel polypropylene film. More specifically, the present invention relates to a polypropylene film which has a high tensile modulus of elasticity and a high tensile strength in a film flow direction (hereinafter abbreviated as MD) and excellent transparency, and can be suitably used as a binding tape and a general packaging film.

[0002]

2. Description of the Related Art Polypropylene films are widely used for various packaging materials, binding tapes and the like because of their excellent mechanical and optical properties.

Generally, a uniaxially stretched polypropylene film obtained by uniaxially stretching a sheet or a film extruded by a T-die method or an inflation method into an MD is used for the binding tape.

However, the above uniaxially stretched polypropylene film has a high MD tensile modulus and MD tensile strength and has a binding strength required for a binding tape application, but has a direction perpendicular to the MD (hereinafter referred to as TD). ), And the balance between the tensile modulus and the tensile strength of MD and TD is poor, resulting in poor mechanical aptitude during automatic packing. Furthermore, there was a problem that the film was easily longitudinally split by the tensile stress of TD.

In addition, uniaxially stretched polypropylene films have significantly lower transparency and transparency than biaxially stretched polypropylene films, so that printing of packaged articles and bar codes cannot be clearly read through the film. There was also.

On the other hand, the biaxially stretched polypropylene film conventionally used has an extremely low tensile modulus and tensile strength of MD, which is the unwinding direction of the film, as compared with the tensile modulus and tensile strength of TD. There was a problem that sufficient binding strength could not be obtained, and thus it could not be used for binding tape applications.

[0007]

In recent years, due to the automation and diversification of packing forms and the use of barcode display,
There has been a need for a binding tape that has good mechanical suitability, does not cause longitudinal tearing, and has excellent transparency.

Accordingly, it is an object of the present invention to provide a binding tape having a sufficiently high tensile modulus and tensile strength of MD, a good balance of MD and TD tensile strength and tensile strength, and excellent transparency. To provide a polypropylene film.

[0009]

From the above viewpoints, the present inventors have conducted intensive studies on the above problems, and as a result, a polypropylene film in which the orientation state of polypropylene crystals with respect to MD and TD has a specific relationship has been found to be a tensile strength of MD. High modulus and tensile strength, MD and TD tensile modulus,
The inventors have found that the balance of tensile strength is good and the transparency is excellent, and the present invention has been completed.

[0010] That is, the present invention relates to an X-ray diffraction method,
The sum of the orientation index in the flow direction of the film (hereinafter abbreviated as MD orientation index) and the orientation index in the direction orthogonal to the flow direction of the film (hereinafter abbreviated as TD orientation index) (MD orientation index +
(TD orientation index) is 0.6 to 1.1, and a ratio of the MD orientation index to the TD orientation index (MD orientation index / TD orientation index) is 0.3 to 0.9. It is a polypropylene film.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polypropylene film of the present invention requires that the MD orientation index and the TD orientation index have the following specific relationship.

That is, the sum of the MD orientation index and the TD orientation index (MD orientation index + TD orientation index) of the polypropylene film of the present invention must be in the range of 0.6 to 1.1. It is preferably in the range of 65 to 1.05, and more preferably in the range of 0.7 to 1.0. If the sum of the MD orientation index and the TD orientation index (MD orientation index + TD orientation index) is less than 0.6, it is not preferable because the tensile modulus and tensile strength of MD and TD cannot be sufficiently obtained. On the other hand, when the sum of the MD orientation index and the TD orientation index (MD orientation index + TD orientation index) exceeds 1.1, the thickness accuracy of the polypropylene film is reduced, the thickness unevenness is increased, and the transparency is reduced. Therefore, it is not preferable.

Further, the ratio of MD orientation index to TD orientation index (MD orientation index / MD orientation index) of the polypropylene film of the present invention.
TD orientation index) needs to be in the range of 0.3 to 0.9, preferably in the range of 0.4 to 0.85, and more preferably in the range of 0.5 to 0.8. Is more preferable. If the ratio of the MD orientation index to the TD orientation index (MD orientation index / TD orientation index) exceeds 0.9, the accuracy of the thickness of the polypropylene film decreases, and the thickness unevenness increases, which is not preferable. Conversely, if the ratio of the MD orientation index to the TD orientation index (MD orientation index / TD orientation index) is less than 0.3, the MD tensile modulus and tensile strength cannot be sufficiently obtained. Is unfavorable because the balance between the tensile modulus and the tensile strength of the film deteriorates, and furthermore, the film tends to be longitudinally torn.

The sum of the above MD orientation index and TD orientation index (MD orientation index + TD orientation index), MD orientation index and T
Considering the ratio of the D orientation index (MD orientation index / TD orientation index), the range of the MD orientation index is 0.15 to 0.53, and preferably 0.18 to 0.48. Also,
The range of the TD orientation index is 0.31 to 0.83,
It is preferably from 35 to 0.75.

In the present invention, the MD orientation index with respect to the MD by the X-ray diffraction method is c
This is an index indicating the degree to which the axis (molecular chain axis) is oriented in the MD of the polypropylene film. As shown by the following equation (1), the plane orientation index ([P
OI]) and the root mean square (<cos ² φ _{c, MD} >) of the direction cosine of the crystal c-axis and MD.

[MD orientation index] = [POI] × <cos ² φ _{c, MD} > (1) The above plane orientation index ([POI]) is defined as a value in which the polypropylene crystal (010) plane is parallel to the film plane. This is an index indicating the degree of plane orientation, and can be determined by the following method.

Using a transmission sample rotating sample apparatus, X-rays are incident from a direction perpendicular to the film surface while rotating the polypropylene film at high speed about an axis perpendicular to the film surface, and the diffraction intensity is measured. The X-ray diffraction intensity curve was separated into an amorphous peak and each crystalline peak, and the (111) plane reflection (2
θ = about 21.4 °) and (040) surface reflection (2θ = about 1
The plane orientation index ([POI]) can be obtained from the ratio of the peak intensities of 7.1 °) by the following equation (2).

[POI] = log ｛1.508 × I ₍₁₁₁₎ / I ₍₀₄₀₎ ｝ (2) where I ₍₁₁₁₎ : peak intensity of (111) surface reflection (count
s) I ₍₀₄₀₎ : peak intensity of (040) surface reflection (counts) Here, the coefficient 1.508 in the above equation is determined by Zet. The Journal of Macromolecular Science, Physics by Z. Mencik
romoleculer Science, Physics) B6 , 101 (1972), the intensity ratio I _{(040) /} I ₍ I _{(040) /} I _{( 111)} calculated from the theoretical intensity I ₍₀₄₀₎ and I ₍₁₁₁₎ when the polypropylene crystal is completely randomly oriented. ₁₁₁₎ = 116.9 / 77.5 = 1.50
8 For example, if the (010) plane of the crystal of the measured polypropylene film is completely randomly oriented with respect to the film plane, the value of [POI] is 0,
The more the (010) plane is oriented parallel to the film plane, the larger the value of [POI].

The root mean square (<cos ² φc _{, MD} >) of the direction cosine of the crystal c-axis and MD is obtained by determining the c-axis (molecular chain axis) of the polypropylene crystal in the plane of the polypropylene film. This is an index indicating the degree of uniaxial orientation to the MD, and can be determined by the following method.

Using a fiber sample measuring device, X-rays are incident perpendicularly to the film surface of the polypropylene film, and the polypropylene film is slowly rotated around an axis perpendicular to the film surface (an axis parallel to the X-ray incident direction). By doing so, the polypropylene crystal (110) plane and (04)
0) Obtain the azimuth intensity distribution curve of the plane. Z. Wu. ZWWilchinsky [Journal of Appli Physics
ed Physcis), 31 , 1969 (1960)].
From the orientation distribution curves (crystal plane density distribution curves) of the (0) plane and the (040) plane, the root mean square <cos ² φ110 _{, MD} > of the direction cosine between the normal of each plane and the MD of the polypropylene film,
<Cos ² φ _{040, MD} > is obtained and the crystal c is obtained by the following equation (3).
The root mean square (<cos ² φc _{, MD} >) of the direction cosine between the axis and the MD is obtained.

<Cos ² φ _{c, MD} > = 1−1.099 <cos ² φ _{110, MD} > −0.901 <cos ² φ _{040, MD} > (3) In the present invention, the TD orientation index by the X-ray diffraction method is used. Is an index indicating the degree to which the c-axis (molecular chain axis) of the polypropylene crystal is oriented to the TD of the polypropylene film. As shown in the following formula (4), the plane orientation index ([POI]) It is obtained by the product of the root mean square (<cos ² φc _{, TD} >) of the direction cosine of the crystal c-axis and TD.

[TD orientation index] = [POI] × <cos ² φ _{c, TD} > (4) The root mean square of the direction cosine of the crystal c axis and TD (<cos ²
φ _{c, TD} 〉) is the c-axis (molecular chain axis) of the polypropylene crystal
Is an index indicating the degree of uniaxial orientation to the TD of the polypropylene film within the film plane, and can be determined by the following method.

In the same manner as in the above-described method of obtaining <cos ² φ _{c, MD} >, the root mean square <co of the direction cosines of the (110) and (040) planes and the TD of the polypropylene film is used.
s ² φ _{110, TD>,} seeking _{^{<cos 2 φ 040, TD>}} , the following (5)
From the formula, the root mean square of the direction cosine of the crystal c-axis and TD (<co
s ² φ _{c, TD} 〉).

<Cos ² φ _{c, TD} > = 1−1.099 <cos ² φ _{110, TD} > −0.901 <cos ² φ _{040, TD} > (5) The polypropylene film of the present invention has the above MD orientation index and TD If the sum of the orientation indices (MD orientation index + TD orientation index) and the ratio of the MD orientation index to the TD orientation index (MD orientation index / TD orientation index) fall within the range specified in the present invention, the effects of the present invention are sufficiently obtained. However, considering the tensile elastic modulus and tensile strength of MD, tensile elastic modulus of MD and TD, balance of tensile strength, and properties such as transparency, the following requirements can be satisfied. preferable.

As a raw material of the polypropylene film of the present invention, a polypropylene having a known crystallinity is used without any particular limitation. Examples of the polypropylene include a propylene homopolymer, a propylene-α-olefin copolymer of propylene and an α-olefin other than propylene, and a mixture thereof.

In the propylene-α-olefin copolymer, the content of monomer units based on one or more α-olefins other than propylene is 2 mol% or less, and more preferably 1 mol% or less. It is preferably an α-olefin copolymer or a mixture thereof. α
-As the olefin, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-
Octene, 1-nonene, 1-decene, 4-methyl-1-
Penten and the like can be mentioned. The propylene-α-olefin copolymer may be any of a random copolymer and a block copolymer, and among them, a random copolymer is preferable.

¹³ C- which shows the crystallinity of the above polypropylene
The isotactic pentad fraction by NMR is not particularly limited, but is preferably in the range of 0.85 to 0.99, and more preferably in the range of 0.90 to 0.98. preferable. Note that the isotactic pentad fraction referred to herein is A.D. Zamberg (A.Zamb
elli) et al. by Macromolecules
es), 13 , 267 (1980), which is the fraction in which five propylene units are continuously determined to have the same configuration as determined based on the peak assignment of the ¹³ C-NMR spectrum.

The melt flow rate of the polypropylene is not particularly limited, but is usually preferably in the range of 0.1 to 20 g / 10 minutes in consideration of the formability into a film. More preferably, the range is 10 g / 10 minutes. The weight average molecular weight is 2
00,000 to 800,000, preferably 250,0
A range from 00 to 450,000 is preferred.

The weight average molecular weight (M
The molecular weight distribution represented by the ratio (Mw / Mn) between w) and the number average molecular weight (Mn) is not particularly limited,
In consideration of the ease of forming the film and the fact that the workability is improved by increasing the melt tension, it is preferably from 2 to 20, and more preferably from 4 to 10. The molecular weight distribution is a value measured by gel permeation chromatography using o-dichlorobenzene as a solvent (hereinafter also referred to as GPC), and the calibration curve is calibrated with standard polystyrene.

The amount of p-xylene soluble at room temperature in the polypropylene is not particularly limited, but is preferably in the range of 8% by weight or less, more preferably in the range of 5% by weight or less.

The melting point of the polypropylene is not particularly limited, but is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, and further preferably 1 ° C. or higher.
It is preferably at least 58 ° C. In addition, the melting point of polypropylene referred to here is a peak temperature of a crystal melting curve at the time of temperature rise measured by a differential scanning calorimeter (hereinafter, also referred to as DSC).

In addition, other resins may be blended in the raw material of the polypropylene film in addition to the polypropylene, as long as the effects of the present invention are not impaired. The resin to be blended is not particularly limited, but is generally ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-octene.
Α such as nonene, 1-decene and 4-methyl-1-pentene
Polyolefin resins such as homopolymers of olefins, copolymers of these α-olefins, or mixtures of two or more of these polymers, aliphatic hydrocarbon resins, and alicyclic hydrocarbons; Thermoplastic resins such as resins, rosin derivatives, terpene resins, terpene phenol resins and the like and petroleum resins such as hydrogenated resins thereof can be mentioned.

The raw materials of the polypropylene film may include, if necessary, a stabilizer, an antioxidant, a chlorine scavenger, an antistatic agent, an antiblocking agent, an antifogging agent, an ultraviolet absorber, a lubricant, and a surfactant. , Pigments, fillers, foaming agents, foaming aids, plasticizers, crosslinking agents, crosslinking aids, flame retardants, dispersants,
Various known additives such as processing aids and fillers may be blended within a range that does not impair the effects of the present invention.

In consideration of imparting more excellent transparency to the polypropylene film of the present invention, it is preferable that a raw material of the polypropylene film contains a nucleating agent.

Examples of the crystal nucleating agent contained in the raw material of the polypropylene film of the present invention include known crystal nucleating agents used for polypropylene such as a polymer nucleating agent, an organic nucleating agent and an inorganic nucleating agent. Can be used without any limitation. Among the above crystal nucleating agents, a polymer crystal nucleating agent is particularly preferable in consideration of the effect of improving the transparency of the obtained polypropylene film, prevention of bleed out from the film, prevention of generation of fish eyes due to aggregation, and the like.

The content of the above-mentioned nucleating agent in the raw material of the polypropylene film is preferably in the range of 0.00001 to 1% by weight. However, the preferable range of the content is slightly different depending on the type of the nucleating agent. As shown, it is preferable to determine for each nucleating agent.

Examples of the polymer crystal nucleating agent include:
Examples thereof include a cyclic olefin polymer, a branched α-olefin polymer having 5 or more carbon atoms, a vinylcycloalkane polymer, and a fluorine-containing polymer.

The above-mentioned cyclic olefin polymer is a polymer of a monomer having a polymerizable double bond in the ring.
A cyclic olefin homopolymer having 4 to 20 carbon atoms, a copolymer of the cyclic olefins, a cyclic olefin 50
A copolymer of at least 80 mol% and at most 50 mol% of other monomers, preferably at least 80 mol% of the above-mentioned cyclic olefin and at most 20 mol% of other monomers can be mentioned.

Particularly, cyclic olefins which can be suitably used in the present invention include cyclobutene, cyclopentene, cyclopentadiene, 4-methylcyclopentene,
4,4-dimethylcyclopentene, cyclohexene, 4
-Methylcyclohexene, 4,4-dimethylcyclohexene, 1,3-dimethylcyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, cycloheptene, 1,3-cycloheptadiene, 1,3,5-
Cycloheptatriene, cyclooctene, 1,5-cyclooctadiene, cyclododecene and the like can be mentioned. Further, the ring of these cyclic olefins may be further substituted with a linear or branched alkyl group.

The crystallinity of the cyclic olefin polymer is preferably 10% or more because the effect of improving the transparency of the polypropylene film tends to increase as the degree of crystallinity indicating the degree of crystallinity increases. , 30% or more, and most preferably 50% or more.

Among the above-mentioned cyclic olefin polymers, a cyclic olefin homopolymer having a high degree of crystallinity, or a block copolymer of cyclic olefins or a cyclic olefin and an α-olefin is preferable.

The method for producing these cyclic olefin polymers is not particularly limited, and may be a known gas phase polymerization, solution polymerization,
Bulk polymerization or the like may be used. The catalyst used for the polymerization is not particularly limited, for example, a metallocene catalyst,
Vanadium catalyst, titanium catalyst, anion polymerization catalyst,
Known catalysts such as a radical polymerization catalyst may be mentioned, and these catalysts may be used alone or in combination.
Among these, preferred catalysts include metallocene-based catalysts, vanadium-based catalysts, and titanium-based catalysts.

The content of the cyclic olefin polymer in the raw material of the polypropylene film is preferably in the range of 0.00001 to 0.1% by weight, and more preferably 0.00005 to 0.05% by weight. Is more preferable, and the range is more preferably 0.0001 to 0.02% by weight.

The above-mentioned branched α-olefin polymer having 5 or more carbon atoms is a polymer of a branched α-olefin having a polymerizable double bond, for example, a branched α-olefin homopolymer having 5 or more carbon atoms, Copolymer of branched α-olefins, 50 mol% or more of the above-mentioned branched α-olefin and 50 mol% or less of other monomers, preferably 80 mol% or more of the above-mentioned branched α-olefin and other monomers 20 And a copolymer having a mole% or less.

In the present invention, the branched α-olefin that can be particularly preferably used has 5 to 10 carbon atoms, and specifically includes 3-methyl-1-butene and 3-methyl-1-
Pentene, 3-ethyl-1-pentene, 4-methyl-1
-Pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene and the like. Can be.

The vinylcycloalkane polymer is a polymer of a vinylcycloalkane having a polymerizable double bond, that is, a polymer in which a cycloalkane group is pendantly bonded from a main chain. Cycloalkane homopolymer, copolymer of the above-mentioned vinylcycloalkanes, 50 mol% or more of the above-mentioned vinylcycloalkane and 50 mol% or less of the other monomer, preferably 80 mol% or more of the above-mentioned vinylcycloalkane and another monomer And a copolymer having 20 mol% or less of a polymer.

In the present invention, particularly preferred vinylcycloalkanes include vinylcyclobutane, vinylcyclopentane, vinyl-3-methylcyclopentane, vinylcyclohexane, vinyl-3-methylcyclohexane, vinylnorbornane and the like. Can be mentioned.

The branched α-olefin polymer having 5 or more carbon atoms and the vinylcycloalkane polymer tend to have a higher effect of improving the transparency of the polypropylene film as the degree of crystallinity indicating the degree of crystallinity increases. The crystallinity is preferably 10% or more, more preferably 30% or more, and most preferably 40% or more.

Among the above-mentioned branched α-olefin polymers and vinylcycloalkane polymers, those having high crystallinity
A branched α-olefin homopolymer or a vinylcycloalkane homopolymer, or a branched α-olefin having 5 or more carbon atoms, a block copolymer of a branched α-olefin and another α-olefin, or a vinylcycloalkane And a block copolymer of vinylcycloalkane and another α-olefin are preferred.

The method for producing the branched α-olefin polymer having 5 or more carbon atoms and the vinylcycloalkane polymer is not particularly limited, and any known gas phase polymerization, solution polymerization, bulk polymerization, or the like may be used. The catalyst used for the above polymerization is not particularly limited, and for example, known catalysts such as a titanium-based catalyst, a vanadium-based catalyst, and a metallocene-based catalyst can be suitably used, and these may be used alone or in combination.

The content of the branched α-olefin polymer having 5 or more carbon atoms in the raw material of the polypropylene film is preferably from 0.0001 to 1% by weight, and more preferably from 0.001 to 1% by weight. The content is more preferably in the range of 0.5% by weight, and particularly preferably in the range of 0.005 to 0.2% by weight.

The content of the vinylcycloalkane polymer in the raw material of the polypropylene film is preferably in the range of 0.00001 to 0.1% by weight, and more preferably 0.00005 to 0.1% by weight. More preferably, it is in the range of 0.05% by weight, more preferably 0.0001 to 0.0%.
Particularly preferred is a range of 2% by weight.

The fluoropolymer includes a homopolymer of a fluoromonomer, a copolymer of fluoromonomers, and a copolymer of a fluoromonomer and a hydrocarbon monomer, particularly an α-olefin. Among them, specific examples of suitable fluoropolymers include, for example, tetrafluoroethylene polymer, 1-fluoroethylene polymer,
1-difluoroethylene polymer, trifluoroethylene polymer, 1-chloro-2,2-difluoroethylene polymer, chlorotrifluoroethylene polymer, hexafluoropropylene polymer, hexafluoropropylene oxoxide polymer, tetrafluoro Ethylene-methyl vinyl ether copolymer, trifluoroethylene-methyl vinyl ether copolymer, tetrafluoroethylene
Perfluorovinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer and the like can be mentioned.

The fluorine-containing polymer tends to have an effect of improving the transparency of the polypropylene film as the crystallinity, which indicates the degree of crystallinity, increases.
%, More preferably 70% or more.

The particle size of the fluoropolymer is not particularly limited, but in consideration of obtaining a polypropylene film having high transparency, the average primary particle size is 2 μm.
Or less, more preferably 1 μm or less.

The preferable content of the fluoropolymer in the raw material of the polypropylene film is preferably in the range of 0.00001 to 0.1% by weight, and more preferably 0.0001 to 0.05% by weight. %, More preferably in the range of 0.001 to 0.02% by weight.

Specific examples of the above-mentioned organic crystal nucleating agent include sorbitol derivatives such as dibenzylidene sorbitol and di (methylbenzylidene) sorbitol, and p-tert.
Metal salts of aromatic carboxylic acids, such as sodium butylbenzoate, sodium β-naphthoate, sodium 1,2-cyclohexanedicarboxylate, aluminum dibenzoate, and basic aluminum di-p-tert-butylbenzoate; Acids and metal salts of aromatic phosphates such as sodium 2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate and the like can be mentioned.

The content of the organic crystal nucleating agent in the raw material of the polypropylene film is 0.00
It is preferably in the range of 5 to 1% by weight,
It is more preferably in the range of 0.5 to 0.5% by weight, and particularly preferably in the range of 0.05 to 0.3% by weight.

Specific examples of the inorganic crystal nucleating agent include talc and mica. The average particle size of the inorganic crystal nucleating agent is preferably 10 μm or less, more preferably 6.0 μm or less, from the viewpoint of preventing deterioration of the film appearance due to generation of fish eyes.

The content of the inorganic crystal nucleating agent in the raw material of the polypropylene film is 0.00
The range of 5 to 0.4% by weight is suitable, and 0.008 to
It is more preferably in the range of 0.2% by weight, and particularly preferably in the range of 0.01 to 0.1% by weight.

In the present invention, the method of mixing the raw materials of the polypropylene film is not particularly limited, and a known mixing method may be employed. For example, a method of mixing the above-described raw materials of the polypropylene film using a screw extrusion kneader such as a single-screw extruder or a twin-screw extruder, a Banbury mixer, a continuous mixer, a mixing roll, or the like may be used.

The method of mixing the above-mentioned nucleating agent with the raw material of the polypropylene film is not particularly limited, and various mixing methods can be adopted. For example, in addition to the above method, if the crystal nucleating agent is a high molecular weight crystal nucleating agent such as a cyclic olefin polymer, a branched α-olefin polymer having 5 or more carbon atoms, or a vinylcycloalkane polymer,
A method of prepolymerizing a polymer crystal nucleating agent in advance and then homopolymerizing propylene or copolymerizing propylene with another α-olefin to obtain a polypropylene polymer containing a polymer crystal nucleating agent, etc. Can be mentioned.

Further, a polypropylene polymer containing a high-concentration polymer-based nucleating agent at a high concentration of 2 to 1000 times is obtained by the method described above, and the polymer is used as a master batch to prepare another polypropylene. It may be diluted to obtain the desired content of the polymer crystal nucleating agent.

The dilution ratio of a general master batch is 20.
By using this method, it is about 100 times.
Even at a considerably large dilution ratio of 2 times or more, the transparency of the polypropylene film, which is an effect of the present invention, can be sufficiently improved.

Although the thickness of the polypropylene film of the present invention is not particularly limited, it is usually preferably in the range of 1 to 500 μm, and more preferably in the range of 5 to 300 μm, in consideration of the strength of the film, film forming property and the like. Is more preferable, and it is more preferable that it is in the range of 10 to 200 μm.

The polypropylene film of the present invention is preferably biaxially stretched in consideration of achieving the structure defined in the present invention.

The method for producing the polypropylene film of the present invention is not particularly limited, but the physical properties specified in the present invention can be easily achieved by the following methods.

That is, in a method for producing a film by a sequential biaxial stretching method by a tenter method, first, the above-mentioned polypropylene film raw material is subjected to a T-die method, an inflation method or the like to form a sheet or a film (hereinafter abbreviated as an unstretched sheet). Mold into Next, the unstretched sheet is supplied to an MD stretching apparatus, and a heating roll temperature of 100 is applied.
4 to 15 times at ~ 170 ° C, preferably 5 to 13 times MD
The film is stretched, and then the tenter temperature is set to 110 using a tenter.
TD at 4 to 15 times, preferably 5 to 13 times at ~ 180 ° C
In the stretching, the area stretching ratio, which is the product of the MD stretching ratio and the TD stretching ratio, is 25 to 120 times, and the ratio of the MD stretching ratio to the TD stretching ratio (MD / TD stretching ratio) is 0. A method of adjusting the stretching conditions so as to be in the range of 4 to 1.5 is mentioned.

In the above method, the polypropylene film of the present invention can be obtained with good reproducibility by producing a film under the following conditions.

In the formation of the unstretched sheet before the MD stretching, the average diameter of the polypropylene spherulite formed inside the formed unstretched sheet is 50 μm or less, preferably 30 μm or less, more preferably 15 μm or less. As described above, it is preferable to appropriately adjust the cooling temperature and various physical properties of the above-described polypropylene film raw material.

As a method for forming an unstretched sheet having a spherulite average diameter in the above range, known methods can be used without any particular limitation. Usually, one or several molten resins extruded into a sheet shape are used. And contact with a cooling roll to cool and solidify. The thickness of the unstretched sheet is appropriately adjusted in consideration of the thickness of the finally obtained film.
The surface temperature of the cooling roll is appropriately adjusted depending on the thickness of the unstretched sheet to be molded, the molding speed, and the like.
-80 ° C, preferably 10-70 ° C, more preferably 20-60 ° C. Further, in forming the unstretched sheet, a method in which a cooling means such as an air knife, an air chamber, a water cooling pan or the like is used in combination with a cooling roll is more preferable in order to enhance the cooling effect and reduce the internal spherulite diameter.

The spherulite diameter of the unstretched sheet varies depending on molding conditions such as sheet thickness, cooling temperature and molding speed, and the type and content of the nucleating agent. Adjustment is preferred. For example, when the thickness of the film to be formed is large, or when the stretching ratio is high, the thickness of the unstretched sheet is large, so that the spherulite diameter of the unstretched sheet tends to be large. Therefore, in this case, the spherulite diameter of the unstretched sheet can be adjusted to the above range by a method of lowering the cooling temperature, a method of lowering the molding speed, or an increase in the content of the crystal nucleating agent. However, if the cooling temperature is too low, the surface of the unstretched sheet may be roughened or deformed, and the cooling efficiency may be deteriorated and the spherulite diameter may be increased. Therefore, the cooling temperature may be appropriately adjusted according to the sheet thickness and the forming speed. Is preferred.

The spherulite diameter of the unstretched sheet is a value determined from the radius of rotation of the scatterer (spherulite) determined by the light scattering method. See R. S. Stein (RSStein) et al. [Journal of Applied Physcics, 33 , 191]
4 (1962)], the scattering intensity I (q) from the density alone is obtained from the Vv scattering intensity ( _IVv ) and Hv scattering intensity ( _IHv ) (=
I _Vv - (4/3) to calculate the I _Hv), Guinier - plot (lnI
(q) The radius of gyration Rg from the gradient of (q, q is the scattering vector)
Ask for. From Rg, the spherulite diameter can be calculated by the following equation (6).

[Spherulite Diameter] = 2 × √ (5/3) × Rg (6) The unstretched sheet having an internal spherulite diameter of 20 μm or more can also be measured by directly observing under a polarizing microscope. .

In the above MD stretching, the c-axis orientation coefficient in the stretching direction of the MD stretched sheet (hereinafter abbreviated as MD stretched sheet) is preferably in the range of 0.6 to 0.95, more preferably 0.1 to 0.95. It is preferable to appropriately adjust the MD stretching ratio, the stretching temperature, and the various physical properties of the polypropylene raw material so as to be in the range of 7 to 0.9 in order to obtain a polypropylene film having an MD orientation index of the present invention.

As a method for obtaining an MD-stretched sheet having a c-axis orientation coefficient in the above range, the unstretched sheet before MD stretching is heated at a temperature of 100 ° C. to 10 ° C. lower than the melting point of the unstretched sheet, preferably at 110 ° C. A method of heating to a temperature lower than the melting point of the unstretched sheet by 15 ° C. or more and stretching the MD by 4 to 15 times, preferably 5 to 13 times is suitably employed.

Further, as the MD stretching conditions, more preferably, a relational expression between the MD stretching ratio and the melting point (° C.) of the above-mentioned polypropylene film raw material; {[MD stretching ratio]
+0.2 ([melting point] -150)} is 6-1.
MD, preferably in the range of 7 to 10
A method of setting stretching conditions is preferable.

The above c-axis orientation coefficient is a value quantitatively representing the degree of uniaxial orientation of the polypropylene crystal in the stretching direction of the sheet along the c-axis (molecular chain axis), and is determined by an X-ray diffraction method. Can be. For details,
The root-mean-square <cos ² φ _{c, Z} > of the direction cosine between the crystal c-axis and the MD stretching direction (Z-axis) is obtained, and the c-axis orientation coefficient can be calculated by the following equation (7).

[C-axis orientation coefficient] = (3 <cos ² φc _{, Z} > −1) / 2 (7) Then, the TD stretching method of the MD stretched sheet obtained by the above method is, for example, a method before TD stretching. MD stretched sheet of 110
5 ° C. or lower than the melting point of the MD stretched sheet, preferably 110 ° C. to 10 ° C. lower than the melting point of the MD stretched sheet.
Heat to a low temperature above 4 to 15 times, preferably 5 to 1
A method of performing TD stretching three times is suitably employed.

Further, as the TD stretching ratio, more preferably, a relational expression between the melting point (° C.) of the raw material of the polypropylene film; ｛[TD stretching ratio] +0.2 ([melting point] −1)
50) The value obtained in｝ is in the range of 6 to 14, preferably 7
A method in which the stretching conditions are set so as to fall within the range of 13 to 13 is preferable.

The area stretching ratio represented by the product of the MD stretching ratio and the TD stretching ratio (MD stretching ratio × TD stretching ratio) is particularly preferably from 25 to 120 times, and more preferably from 30 to 120 times in the above-mentioned range. More preferably, it is 100 times. Further, the ratio of the MD stretching ratio to the TD stretching ratio (MD / TD stretching ratio) is preferably in the range of 0.4 to
1.5 is preferable, and more preferably 0.5 to 1.4.

Further, in the above-mentioned production method, a method of performing a heat treatment at 80 to 180 ° C. while allowing the MD and TD to relax 0 to 15% after the biaxial stretching, if necessary, may be used in combination. Needless to say, after these stretching, if necessary, the film may be stretched again to MD or TD, and a stretching method such as multi-stage stretching or rolling may be combined in MD stretching.

Further, one or both surfaces of the polypropylene film of the present invention may be subjected to a surface treatment such as a corona discharge treatment if necessary.

Further, as long as the effects of the present invention are not impaired,
For the purpose of imparting functions such as heat sealability, a heat seal layer may be laminated on one or both surfaces of the polypropylene film of the present invention. In particular, when packaging is automatically performed by a machine, it is desirable because heat welding can be easily performed by the heat seal layer.

As the resin used for the heat seal layer, a known polyolefin resin having heat sealability can be used without any limitation. For example, a propylene homopolymer and / or a propylene-α-olefin copolymer having a monomer unit based on an α-olefin other than propylene of 15 mol% or less, preferably 10 mol% or less.
A polyolefin composition or the like comprising 95% by weight and a polyolefin having a monomer unit based on an α-olefin having 4 or more carbon atoms of 15% by mole or more, preferably 20% by mole or more is suitably used.

The α-olefin of the propylene-α-olefin copolymer includes, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-
Examples thereof include methyl-1-pentene, and among them, ethylene and 1-butene are preferable. The above propylene-α
As the olefin copolymer, a propylene-ethylene copolymer, a propylene-1-butene copolymer, and a propylene-ethylene-1-butene copolymer are particularly preferably used.
The method of copolymerization may be either a random copolymer or a block copolymer, but a random copolymer is preferred. The melt flow rate of the propylene homopolymer and the propylene-α-olefin copolymer is generally in the range of 2 to 20 g / 10 minutes.

On the other hand, the polyolefins include homopolymers of α-olefins having 4 or more carbon atoms and those α-olefins having 15 mol% or more of monomer units based on the α-olefins having 4 or more carbon atoms. -Copolymers of olefins with other α-olefins such as propylene and ethylene. As the type of the copolymer, any of a random copolymer and a block copolymer may be used, but a random copolymer is preferred. As the α-olefin having 4 or more carbon atoms, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-
And methyl-1-pentene.
-Butene is preferred. The polyolefin is, in particular, a propylene-1-butene copolymer, propylene-ethylene-
1-butene copolymer is preferably used. The melt flow rate of the polyolefin is usually 2 to 20.
It is generally in the range of g / 10 minutes.

The thickness of the heat seal layer is not particularly limited. However, if the thickness is more than necessary, the rigidity and transparency of the laminate are reduced.
%, More preferably in the range of 2 to 15%.

The method for laminating the heat seal layer is not particularly limited. Generally, polypropylene and a resin for the heat seal layer are melt-coextruded from a T-die or a circular die and then biaxially stretched, or polypropylene is melted. After extrusion and uniaxial stretching to MD, a method in which the resin for the heat sealing layer is melt-extruded thereon and stretched to TD is suitably adopted.

[0090]

According to the present invention, a polypropylene film having a high tensile modulus and tensile strength of MD, a good balance of tensile modulus and tensile strength between MD and TD, and improved transparency is provided. Obtainable.

As apparent from the above description, the polypropylene film of the present invention has MD and TD molecular chain orientations within a specific range and a high MD orientation. It has high tensile strength and exhibits excellent physical properties that cannot be realized with conventional polypropylene films. Therefore, the polypropylene film of the present invention can be suitably used not only for binding tapes but also for general packaging films.

[0092]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples. In addition, the following methods evaluated the polypropylene film and raw material obtained in the following Examples and Comparative Examples.

(1) MD Orientation Index, TD Orientation Index The MD and TD orientation indices were calculated by the following method using the root mean square (<cos ² φc _{, MD} >, <cos ²
φ _{c, TD} >) was calculated and calculated by the above equation.

(1-1) Plane Orientation Index (POI) Using an X-ray diffractometer JDX-3500 manufactured by JEOL Ltd.
The measurement was performed under the following conditions.

Target: Copper (Cu-Kα ray) Tube voltage-tube current: 40 kV-400 mA X-ray incidence method: vertical beam transmission method Monochromatization: graphite monochromator Divergence slit: 0.2 mm Light receiving slit: 0.4 mm Detector : Scintillation counter Measurement angle range: 9.0 to 31.0 ゜ Step angle: 0.04 ゜ Counting time: 4.0 seconds Sample rotation speed: 120 rotations / min In this case, the film is cut out into a circle of 27mmφ, and this is cut out. The measurement was carried out by stacking the layers so as to have a thickness of about 3 mm and mounting the sample on a rotary sample apparatus for transmission method attached to a wide-angle goniometer. The peak separation was performed using a general peak separation program, which is software attached to the instrument.
After removing the background due to air scattering or the like in the range of 31 °, it was separated into an amorphous peak and each crystalline peak by a general peak separation method using a Gaussian function and a Lorentz function. The plane orientation index was calculated from the peak intensities of the (040) plane reflection and the (111) plane reflection by the method described above.

(1-2) The root mean square of the direction cosine (<cos ² φ
_{c, MD} >, <cos ² φc _{, TD} >) A fiber sample device was attached to an X-ray diffractometer JDX-3500 manufactured by JEOL Ltd., and measurement was performed under the following conditions.

Target: Copper (Cu-Kα ray) Tube voltage-Tube current: 40 kV-400 mA X-ray incidence method: Vertical beam transmission method Monochromatization: Graphite monochromator Collimator: 1 mmφ pinhole Light receiving slit: 2 mmφ pinhole Detector: Scintillation counter a) 2θ scanning (Bragg angle) measurement Measuring angle range (2θ): 8 to 32 ° Step angle: 0.1 ° Counting time: 2.0 seconds b) In-plane rotation (β rotation) measurement Measuring angle range ( β): -20 to 110 ° Step angle: 0.5 ° Counting time: 2.0 seconds In this case, the stretching direction of the film is matched, and the length is 15 mm.
(MD) × 5 mm width (TD), cut out into a strip shape, overlapped with each other in a drawing direction so as to have a thickness of about 1 mm, and attached to a fiber sample device. Was incident, and 2θ scanning was performed by the vertical transmission method to determine the Bragg angles (2θ °) of the (110) and (040) planes of the polypropylene crystal. Next, the counter is fixed to the Bragg angle of the (110) plane, and the sample is rotated in-plane (β
Rotation), and the azimuthal intensity distribution curve was measured for the (110) plane. Similarly, the azimuthal intensity distribution curve of the (040) plane was measured. The background intensity due to air scattering or the like at the (110) plane and (040) plane reflection positions of the X-ray diffraction profile measured by 2θ scanning was obtained,
The (110) and (040) planes were respectively subtracted from the azimuthal intensity distribution curves of the (110) and (040) planes.
A plane orientation distribution curve (crystal plane density distribution curve) was obtained. From these orientation distribution curves, <cos ² φ
_{c, MD} > and <cos ² φ _{c, TD} > were obtained.

The c-axis orientation coefficient of the MD stretched sheet is as follows:
A strip-shaped sample obtained by cutting the MD stretched sheet in the stretching direction to a size of 15 mm × 5 mm in width was mounted on a fiber sample device, and <cos ² φ _{c, Z} > was determined in the same manner to calculate the c-axis orientation coefficient.

(2) Isotactic pentad fraction (mmmm), α-olefin content Using JNM-GSX-270 ( ^13C- nuclear resonance frequency of 67.8 MHz) manufactured by JEOL Ltd. under the following conditions: It was measured.

Measurement mode: 1H-complete decoupling Pulse width: 7.0 microseconds (C45 degrees) Pulse repetition time: 3 seconds Integration count: 10,000 times Solvent: Mixed solvent of ortho-dichlorobenzene / heavy benzene (90/10 (% By volume) Sample concentration: 120 mg / 2.5 ml Solvent Measurement temperature: 120 ° C. In this case, the isotactic pentad fraction is ¹³ C—N
It was determined by measuring the splitting peak in the methyl group region of the MR spectrum. The peak in the methyl group region was assigned according to the method described in A. According to A. Zambelli et al. [Macromolecules, 13 , 267 (1980)].

(3) Melt flow rate (MFR) Measured according to ASTM 1238.

(4) Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) High temperature GPC apparatus SSC-7100 manufactured by Senshu Kagaku
Was measured under the following conditions.

Solvent: ortho-dichlorobenzene Flow rate: 1.0 ml / min Column temperature: 145 ° C. Detector: high-temperature differential refraction detector Column: “SHODEX UT” manufactured by Showa Denko 8
07, 806M, 806M, 802.5 are connected in series and used.

Sample concentration: 0.1% by weight Injection amount: 0.50 ml (5) Room temperature p-xylene soluble matter [p-Xy.sol.] 1 g of the raw material polymer was added to 100 ml of p-xylene.
After the temperature was raised to 120 ° C. with stirring, stirring was further continued for 30 minutes to completely dissolve the polymer to prepare a uniform solution. The p-xylene solution was allowed to cool to room temperature (23 ° C.) and then left at room temperature (23 ° C.) for 24 hours. Thereafter, the precipitated gel was separated from the gel, and the amount of soluble matter was determined by completely concentrating the p-xylene solution.

Room temperature p-xylene solubles [p-Xy.sol.]
Is determined by the following equation.

[P-Xy.sol.] = {P-xylene solubles (g) / polymer 1 (g)} × 100 (% by weight) (6) Melting point Using a DSC 6200 DSC device manufactured by Seiko Electronics Co., Ltd.
The measurement was performed under the following conditions.

Sample amount: about 5 mg Atmospheric gas: nitrogen (flow rate: 20 ml / min) Temperature condition: After maintaining at 230 ° C. for 10 minutes, 10 ° C. /
The temperature was lowered to 30 ° C. per minute, and the endothermic behavior of melting when the temperature was subsequently raised at 10 ° C./min was measured.

(7) Spherulite average diameter of unstretched sheet Vv scattering and Hv scattering were measured under the following conditions using a solid light scattering measurement device DYNA-100 manufactured by Otsuka Electronics Co., Ltd.

Light source: 5 mW He-Ne laser Angle range: 1.5 to 10 ° Step angle: 0.5 ° ND filter: 0.5 Detector: Photomultiplier for photon counting In this case, a microtome was used. MD for stretched sheet
A slice having a thickness of about 10 μm was cut out perpendicularly to the sample, and a laser beam was vertically incident on the sample slice to measure Vv scattering and Hv scattering.

(8) Tensile modulus According to JIS-K7113, the tensile modulus was measured by the following method.

MD and T from polypropylene film
A sample was cut out into a strip having a width of 10 mm and a length of 100 mm in D, and both ends of the sample were fixed with chucks of a tensile strength measuring machine (Autograph; manufactured by Shimadzu Corporation). in this case,
The sample was prepared such that the distance between the chucks in the length direction was 20 mm. Perform a tensile test at a tensile speed of 20 mm / min.
A tensile stress-strain curve was created. The tensile modulus (Em) was calculated by the following equation using the linear portion at the beginning of the tensile stress-strain curve.

In this example, the MD tensile modulus was 1800.
MPa or more, MD tensile modulus / TD tensile modulus is 0.6
A score of 5 or more was accepted.

Em = Δδ / Δε where Δδ: difference in stress between two points on the straight line due to the original average cross-sectional area of the sample Δε: difference in strain between the same two points (9) Tensile strength MD from polypropylene film And TD, width 10
mm, cut out the sample into a 100 mm long strip,
Both ends of the sample were fixed with chucks of a tensile strength measuring machine (Autograph; manufactured by Shimadzu Corporation). In this case, the sample was prepared so that the distance between the chucks in the length direction was 40 mm.
A tensile test was performed at a tensile speed of 300 mm / min, and the tensile stress at the sample breaking point was defined as the tensile strength.

In this example, the MD tensile strength was 160MP.
a, the MD tensile modulus / TD tensile modulus was 0.50 or more.

(10) Transparency (Mapping Value) An optical comb of 0.1 was used using a mapping property measuring device manufactured by Suga Test Instruments Co., Ltd.
Using a 25 mm length, the comb direction was made parallel to the TD (transverse stretching direction) of the biaxially stretched polypropylene film, and the mapping value was measured.

Example 1 (Preparation of Raw Material Pellets) Polypropylene A shown in Table 1
100 parts by weight of a powder of 2,6-
0.1 parts by weight of di-t-butylhydroxytoluene, 0.1 parts by weight of calcium stearate as a chlorine scavenger, 0.3 parts by weight of stearyl diethanolamide as an antistatic agent, and an average particle size of 0.1 as an antiblocking agent.
After adding 0.2 parts by weight of 8 μm of fused spherical silica and mixing with a Henschel mixer for 5 minutes, a screw diameter of 65 μm was added.
The pellets were extruded at 230 ° C. using an extruder having a diameter of mm to granulate the pellets to obtain raw material pellets.

[0117]

[Table 1]

(Production of Biaxially Stretched Film) Using the obtained polypropylene raw material pellets, a biaxially oriented film was produced by the following method. The polypropylene raw material pellets were heated and melted at 280 ° C. using a T-die sheet extruder having a screw diameter of 90 mmφ, extruded, and formed into a raw unstretched sheet having a thickness of about 2 mm with a cooling roll at 30 ° C.
The unstretched sheet was sampled, and the average spherulite diameter at the center was measured. The results are shown in Table 2. Next, a biaxially stretched film was manufactured from the unstretched sheet using a tenter-type sequential biaxial stretching apparatus as follows. First, the unstretched sheet was longitudinally stretched 6.8 times in MD by a hot roll stretching machine to obtain an MD stretched sheet. The MD stretched sheet was sampled, and the c-axis orientation coefficient at the center was measured. The results are shown in Table 2. Subsequently, the MD stretched sheet was stretched to TD with a mechanical magnification of 8.0 times by TD with a tenter transverse stretching machine,
Heat treatment was performed by relaxing the TD by 8% to form a biaxially stretched film having a thickness of 50 μm. In addition, the thickness of the biaxially stretched film was adjusted by the extrusion amount of the T-die sheet extruder (the thickness of the raw unstretched sheet).

Thickness and thinness accuracy due to stretching unevenness of the biaxially stretched film is determined by a film thickness pattern (thickness variation) measured using an infrared thickness measuring machine WEB GAGE manufactured by Yokogawa Electric Corporation installed between the tenter winding machines. Evaluation was made according to the following criteria.

A: Less than ± 1.0 μm O: ± 1.0 μm or more and less than 1.5 μm Δ: ± 1.5 μm or more and less than 2.0 μm ×: ± 2.0 μm or more On one surface of the biaxially stretched film, follow a conventional method. 30W min / m
After performing corona discharge treatment of No. 2 and winding up, the obtained biaxially stretched film was aged at 35 ° C. for 3 days. After aging, the MD orientation index of the obtained biaxially stretched film, T
The D orientation index, MD tensile modulus, TD tensile modulus, MD tensile strength, TD tensile strength, and mapping value (transparency) were measured. The results are shown in Table 2.

Example 2, Comparative Examples 1 and 2 The same procedure as in Example 1 was carried out except that the polypropylene A of Example 1 was used and the stretching ratio was as shown in Table 2. Table 2 shows the results.
It was shown to.

Example 3 and Comparative Example 3 The same procedure as in Example 1 was carried out except that polypropylene B shown in Table 1 was used and the stretching ratio was as shown in Table 2. The results are shown in Table 2.

Examples 4 to 6 and Comparative Examples 4 and 5 The same procedure as in Example 1 was carried out except that polypropylene C shown in Table 1 was used and the stretching ratio was as shown in Table 2. The results are shown in Table 2.

Comparative Example 6 The same procedure as in Example 1 was carried out except that the polypropylene D shown in Table 1 was used and the stretching ratio was as shown in Table 2. The results are shown in Table 2.

Examples 7 and 8 and Comparative Example 7 The same procedures as in Example 1 were carried out except that the polypropylene E shown in Table 1 was used and the stretching ratio shown in Table 2 was used. The results are shown in Table 2.

Example 9 An average particle size of 4.2 μm was added to polypropylene C as a nucleating agent.
m was performed in the same manner as in Example 1 except that 0.03% by weight of talc was added and the stretching ratio was set as shown in Table 2. The results are shown in Table 2.

Example 10 (Polymerization of cyclopentene) W. Kaminsky et al. [Makromolekulare Chemie, 190 , 51]
5 (1989). 2000
Under a nitrogen atmosphere in a glass reactor equipped with a ml stirrer,
500 ml of toluene, 500 mmol of methylaluminoxane and 0.5 mmol of dimethylsilylenebisindenylzirconium dichloride were introduced, and the inside of the system was heated to 60 ° C. Polymerization was started by adding 100 ml of cyclopentene, and polymerization was performed at 60 ° C. for 4 hours. The reaction mixture containing the resulting solid was added to a large amount of acidic methanol to terminate the polymerization. The obtained solid was filtered and dried under reduced pressure to obtain 63.5 g of polycyclopentene. The crystallinity determined by X-ray diffraction was 64%.

The polycyclopentene obtained above (in the table, P
CP) (abbreviated as CP) as a crystal nucleating agent at a content shown in Table 2 was added to polypropylene C, and the stretching was performed in the same manner as in Example 1 except that the stretching ratio was as shown in Table 2. The results are shown in Table 2.

Examples 11 and 12 and Comparative Example 8 The polycyclopentene (abbreviated as PCP in the table) obtained in Example 10 was used as a nucleating agent in a content shown in Table 2 by adding it to polypropylene C and used in Table 2. The procedure was performed in the same manner as in Example 1 except that the stretching ratio was set to. The results are shown in Table 2.

Examples 13 and 14, Comparative Example 9 The polycyclopentene (abbreviated as PCP in the table) obtained in Example 10 was used as a crystal nucleating agent by adding it to polypropylene A at the content shown in Table 2, The procedure was performed in the same manner as in Example 1 except that the stretching ratio was set to. The results are shown in Table 2.

Example 15 (Preparation of Titanium Compound) A solid titanium component was prepared according to the method of Example 1 in JP-A-58-38006. That is, anhydrous magnesium chloride 9.5
g, decane 100 ml and 2-ethylhexyl alcohol 47 ml (300 mmol) were heated and stirred at 125 ° C. for 2 hours, and 5.5 g of phthalic anhydride (3
7.5 mmol), and the mixture was further stirred and mixed at 125 ° C. for 1 hour to obtain a homogeneous solution. After cooling to room temperature, 400 ml of titanium tetrachloride kept at -20 ° C
(3.6 mmol) over 1 hour. The temperature of the mixture was raised to 110 ° C. over 2 hours. When the temperature reached 110 ° C., 5.4 ml (25 mmol) of diisobutyl phthalate was added, and the mixture was kept under stirring at the same temperature for 2 hours. After 2 hours of reaction,
The solid part was collected by hot filtration, and this solid part was 2,000 m
After resuspending in 1 l of titanium tetrachloride, the mixture was heated again at 110 ° C. for 2 hours. After the 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 solid titanium catalyst component prepared by the above production method was stored as a heptane slurry. The composition of the solid titanium catalyst component was 2.1% by weight of titanium and 57.0% of chlorine.
% Of magnesium, 18.0% by weight of magnesium and 21.9% by weight of diisobutyl phthalate.

(Preliminary polymerization of 3-methyl-1-butene) Purified hexane 6000 was placed in a 10-L polymerization vessel purged with nitrogen.
ml, 100 mmol of triethylaluminum and 10 mmol of a solid titanium catalyst component in terms of titanium atom, and then 3-methyl-1-butene was added to the titanium component 10 as a whole.
It was continuously introduced into the reactor for 2 hours so that the amount became 80 g per g. During this time, the temperature was kept at 20 ° C. After 2 hours, the introduction of 3-methyl-1-butene was stopped and the reactor was thoroughly purged with nitrogen. The solid portion of the obtained slurry was washed five times with purified hexane, and the titanium catalyst component-containing poly-
3-Methyl-1-butene was obtained. At this time, poly-3-
The weight of methyl-1-butene was 72 g. The crystallinity determined by X-ray diffraction was 60%.

(Main Polymerization of Propylene) 500 kg of propylene was charged into a 2000-liter polymerization vessel subjected to nitrogen substitution, and 1.64 mol of triethylaluminum, 0.164 mol of ethyltriethoxysilane, and 0.0082 mol of cyclohexylmethyldimethoxysilane. After further charging 10 L of hydrogen, the internal temperature of the polymerization vessel was raised to 65 ° C. Titanium catalyst component-containing poly-3-methyl-1-butene was charged with 0.00656 mol of titanium atoms, and then the internal temperature of the polymerization vessel was raised to 70 ° C., and propylene polymerization was performed for 1 hour. One hour later, unreacted propylene was purged to obtain a white granular polymer. The resulting polymer was 7
Drying under reduced pressure was performed at 0 ° C. The total polymer yield is 143k
g. Poly-3-methyl-1- in poly-3-methyl-1-butene-containing polypropylene F determined from yield
The butene content was 0.033% by weight. The obtained polypropylene F had an isotactic pentad fraction (mmmm), a melt flow rate (MFR), a molecular weight distribution (Mw / Mn), and a p-xylene soluble matter at room temperature (pX).
y.sol.) and the melting point are shown in Table 1.

The same procedure as in Example 1 was carried out except that the polypropylene F containing 0.033% by weight of poly-3-methyl-1-butene (abbreviated as P-3M1B in the table) obtained above was used and the stretching ratio was as shown in Table 2. The same was done. The results are shown in Table 2.

[0135]

[Table 2]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00 C08L 23:10

Claims (2)

[Claims] 1. The sum of the orientation index (MD orientation index) in the direction of flow of a film and the orientation index (TD orientation index) in a direction perpendicular to the direction of flow of the film, obtained by an X-ray diffraction method (MD orientation index + TD orientation index). ) Is 0.6 to 1.1, and the ratio of the MD orientation index to the TD orientation index (MD orientation index / TD)
A polypropylene film having an orientation index of 0.3 to 0.9. 2. The polypropylene film according to claim 1, which contains 0.00001 to 1% by weight of a nucleating agent.