JP2022154923A - Film, and method for producing film - Google Patents

Abstract

To provide a film that has bag-breaking resistance and is relatively easy to cut.SOLUTION: A film comprises at least two olefin polymers. The at least two olefin polymers form a sea-island phase separation structure comprising continuous phases and non-continuous phases. The degree of orientation of the film in the MD direction, determined by wide-angle X-ray scattering measurement, is 76% or more.SELECTED DRAWING: None

Description

The present invention relates to films and methods of manufacturing films.

Films containing at least two olefinic polymers are used in a variety of applications. For example, such films may be used as sealant layers in multilayer films used as packaging materials. A multi-layer film having such a sealant layer can be heat-sealed with the sealant layer inside to form a storage space, thereby forming a packaging bag. A package can be formed by storing and sealing an article in such a packaging bag.

The packaging bag as described above is to be easily torn by hand when the article is taken out of the package (easily cut), and to form a package that is hard to break when dropped (breakage resistance). requested. Therefore, the film used as the sealant layer is also required to have easy-to-cut properties and resistance to bag breakage. As a film capable of imparting such easy-to-cut properties and bag breakage resistance to packaging bags, Patent Document 1 describes two kinds of propylene-based polymers, an ethylene-based polymer, and a predetermined crystal nucleating agent. A film containing a ratio of

JP 2019-172780 A

However, even with the above-mentioned films, there is room for improvement in terms of ease of cutting, and there is a demand for films having superior ease of cutting.

Accordingly, an object of the present invention is to provide a film having bag breakage resistance and comparatively excellent easy-to-cut properties, and to provide a method for producing such a film.

The film according to the present invention is
A film containing at least two olefinic polymers,
At least two kinds of olefin-based polymers form a sea-island phase separation structure consisting of a continuous phase and a discontinuous phase,
The degree of orientation in the MD direction of the film determined by wide-angle X-ray scattering measurement is 76% or more.

The method for producing a film according to the present invention comprises:
A method for producing the above film,
a melt-kneading step of melt-kneading a mixture containing at least two types of propylene-based polymers, an ethylene-based polymer, and a phosphoric acid ester metal salt-based nucleating agent;
an extrusion step of extruding the kneaded product obtained in the melt-kneading step into a sheet;
A cooling step in which the sheet-like kneaded product obtained in the extrusion step is cooled by pressing it against a cooling roll with gas blown from an air chamber;
A film forming step of forming a film by forming a sheet-like kneaded product,
In the cooling step, the air volume of gas blown out from the air chamber is adjusted so that the gas pressure in the air chamber is 50 Pa to 300 Pa.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide a film having bag breakage resistance and comparatively excellent easy-to-cut properties, and a method for producing such a film.

The film according to this embodiment contains at least two olefinic polymers. Such at least two kinds of olefinic polymers form a sea-island type phase separation structure consisting of a continuous phase and a discontinuous phase in the film.

In addition, in the film according to the present embodiment, the degree of orientation in the MD direction (flow direction of the film during film formation) determined by wide-angle X-ray scattering measurement is 76% or more, preferably 76% to 98%. Yes, more preferably 76% to 95%. The degree of orientation in the MD direction can be determined by the method described in Examples below. In addition, the degree of orientation in the MD direction can be changed by adjusting the gas pressure in the air chamber and adjusting the force for pressing the sheet-like kneaded material against the cooling roll in the film manufacturing method described later. Specifically, the degree of orientation in the MD direction can be increased by decreasing the gas pressure in the air chamber, and the degree of orientation in the MD direction can be decreased by increasing it.

Furthermore, the film according to this embodiment preferably satisfies the following formulas (1) and (2). Nx, Ny, Nz, and θ in the following formulas (1) and (2) can be determined by the method described in Examples below. In addition, Nx, Ny, Nz, and θ can be changed by adjusting the gas pressure in the air chamber and adjusting the force for pressing the sheet-like kneaded material against the cooling roll in the film manufacturing method described later. can be done. Specifically, by decreasing the gas pressure in the air chamber, Nx can be increased and Ny and Nz can be decreased, and by increasing it, Nx can be decreased and Ny and Nz can be increased.

(Nx×cos θ−Ny×cos θ)/d≧3.0×10 ⁻⁸ (1)
(Nx−(Ny+Nz)/2)/d≧3.4×10 ⁻⁸ (2)

(In the formula,
Nx represents the refractive index of the slow axis of the film determined by three-dimensional refractive index measurement.
Ny represents the refractive index of the fast axis of the film determined by three-dimensional refractive index measurement.
Nz indicates the refractive index in the thickness direction of the film determined by three-dimensional refractive index measurement.
θ indicates the angle (°) formed between the MD direction of the film and the slow axis determined by three-dimensional refractive index measurement.
d indicates the film thickness (nm). )

As the olefin polymer, for example, a propylene polymer can be used. The propylene-based polymer is a polymer containing 50% by mass or more (preferably more than 50% by mass) of monomer units derived from propylene, and may be a propylene homopolymer or a propylene-based copolymer. may

Such a propylene-based polymer may be a propylene-based polymer A-1 containing preferably 95 mass or more of monomer units derived from propylene. The propylene-based polymer A-1 may contain more preferably 97% by mass or more, more preferably more than 99% by mass, of monomer units derived from propylene. Such propylene-based polymer A-1 may be a propylene homopolymer or a propylene-based copolymer.

When the propylene-based polymer A-1 is a propylene-based copolymer, the propylene-based polymer A-1 contains, in addition to monomer units derived from propylene, ethylene and/or an α- It may also contain monomeric units derived from olefins. In such a case, the content of monomer units derived from ethylene and/or an α-olefin having 4 to 12 carbon atoms in the propylene-based polymer A-1 is preferably 5% by mass or less, more preferably It is more than 0% by mass to 3% by mass, more preferably more than 0% by mass to 1% by mass. Examples of α-olefins having 4 to 12 carbon atoms include 1-butene, 1-hexene, 1-octene and the like, preferably 1-butene.

The propylene-based polymer may also be a propylene-based polymer A-2 containing preferably 50% to 90% by mass of monomer units derived from propylene. The propylene-based polymer A-2 may contain more preferably 50% to 80% by mass, more preferably 60% to 80% by mass, of monomer units derived from propylene.

The propylene-based polymer A-2 may be a propylene-ethylene copolymer A-21 containing monomer units derived from ethylene. The content of the ethylene-derived monomer units in the propylene-ethylene copolymer A-21 is preferably 10% by mass to 50% by mass, and from the viewpoint of excellent blocking resistance and bag breakage resistance, more It is preferably 20% by mass to 50% by mass, more preferably 20% by mass to 40% by mass.

When the film according to the present invention contains the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21 as the olefin-based polymer, the propylene-based polymer A-1 and the propylene-ethylene copolymer A- The mass ratio of the propylene-based polymer A-1 to the total mass of the propylene-based polymer A-1 and 21 is preferably 50% by mass to 90% by mass, and more preferably 60% by mass to 90% by mass, more preferably 60% by mass to 80% by mass. In addition, the mass ratio of the propylene-ethylene copolymer A-21 to the total mass of the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21 should be considered in terms of the balance between heat sealability and blocking resistance. From the viewpoint of being excellent, the content is preferably 10% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, and even more preferably 20% by mass to 40% by mass.

The film according to this embodiment may contain a propylene-based polymer composition containing at least two propylene-based polymers as described above. The combination of at least two propylene-based polymers contained in the propylene-based polymer composition includes, for example, propylene homopolymers (e.g., propylene polymers having different physical properties, molecular weights, molecular weight distributions, and/or stereoregularities). It may be a combination of homopolymers), a combination of a propylene homopolymer and a propylene-based copolymer, or a combination of propylene-based copolymers. The at least two types of propylene-based polymers contained in the propylene-based polymer composition are at least two types of propylene-based polymers that constitute a multi-stage polymer formed by performing a plurality of polymerization steps in stages. or at least two separately polymerized propylene-based polymers. Preferably, the propylene-based polymer composition contains a multi-stage propylene-based polymer composed of at least two propylene-based polymers.

The propylene-based polymer composition has, for example, a cold xylene-soluble portion content of 5% by mass to 25% by mass, and an intrinsic viscosity [η] _CXS of the cold xylene-soluble portion of 1.5 dL/g to 3. .5 dL/g, the content of the cold xylene-insoluble portion is 75% by mass to 95% by mass, and the intrinsic viscosity [η] _CXIS of the cold xylene-insoluble portion is 1.0 dL/g to 2.5 dL/g. (hereinafter also referred to as "propylene-based polymer composition (A)"). The propylene-based polymer composition (A) preferably has a cold xylene-soluble portion content of 5% to 20% by mass, more preferably 10% to 20% by mass. In addition, the propylene-based polymer composition (A) preferably has a cold xylene soluble portion intrinsic viscosity [η] _CXS of 1.7 dL/g to 3.2 dL/g, more preferably 2.0 dL/g. g~3.2 dL/g. The propylene-based polymer composition (A) preferably has a cold xylene-insoluble portion content of 80 to 95% by mass, more preferably 80 to 90% by mass. In addition, the propylene-based polymer composition (A) preferably has a cold xylene-insoluble portion intrinsic viscosity [η] _CXIS of 1.5 dL/g to 2.5 dL/g, more preferably 1.5 dL/g. ~2.0 dL/g. The content of the propylene-based polymer composition (A) in the film according to the present embodiment is preferably 75% by mass to 95% by mass, more preferably 80% by mass to 95% by mass, and still more preferably 80% by mass to 90% by mass.

The content of the cold xylene soluble portion, the intrinsic viscosity [η] _CXS of the cold xylene soluble portion, the content of the cold xylene insoluble portion, and the intrinsic viscosity [η] _CXIS of the cold xylene insoluble portion are ethylene and / Alternatively, the numerical values can be changed by changing the type and content of monomers derived from α-olefins having 4 to 12 carbon atoms, composition distribution, and molecular weight. In addition, the content of the cold xylene soluble portion, the intrinsic viscosity [η] _CXS of the cold xylene soluble portion, the content of the cold xylene insoluble portion, and the intrinsic viscosity [η] _CXIS of the cold xylene insoluble portion are determined by the implementation described later. It can be obtained by the method described in the example.

Examples of the propylene-based polymer composition contained in the film according to the present embodiment include those satisfying the following formula (3) (hereinafter also referred to as "propylene-based polymer composition (C)"). The content of the propylene-based polymer composition (C) in the film is preferably from 5% by mass to 30% by mass, more preferably from 5% by mass to 25% by mass, and even more preferably from 5% by mass to 20% by mass.

MT ^C >70×MFR ^C-1.1 (3)

(In the formula,
MTC indicates the melt tension (mN) measured at a temperature of 190° ^C and a take-up speed of 15.7 m/min.
MFR ^C indicates the melt flow rate (g/10 min) measured at a temperature of 230°C and a load of 2.16 kg. )

The numerical value of the melt tension can be changed by changing the molecular weight of the propylene-based polymer contained in the propylene-based polymer composition, the degree of branching of molecular chains, or the degree of cross-linking between molecular chains. The value of MFR ^C can be changed by changing the molecular weight of the propylene-based polymer contained in the propylene-based polymer composition. Also, the melt tension and MFR ^C can be determined by the methods described in Examples below.

The method for producing the propylene-based polymer as described above is not particularly limited. For example, as a method for producing the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21, a Ziegler-Natta catalyst, a metallocene catalyst, or the like is used to polymerize raw materials such as propylene and ethylene. method. The propylene-based polymer A-1 and the propylene-ethylene copolymer A-21 can be polymerized in an inert solvent such as hexane, heptane, toluene, or xylene, or in liquid propylene or ethylene. A method of polymerizing, a method of adding a catalyst to gaseous propylene or ethylene and polymerizing in a gas phase, or a method of polymerizing by combining these methods can be mentioned.

Further, as a method for producing the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21, from the viewpoint of productivity, the propylene-based polymer A is preferably produced in the absence of substantially an inert solvent. -1 is performed, and then propylene and ethylene are polymerized in the gas phase in the presence of the propylene-based polymer A-1 to produce a propylene-ethylene copolymer A-21. It is a method of performing the second step. Thereby, a propylene-based multistage polymer containing the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21 can be produced.
As a method for adjusting the content of ethylene-derived monomer units in such a propylene-based multistage polymer, in each step of polymerization, a molecular weight modifier such as hydrogen gas or a metal compound and ethylene are added in appropriate amounts, respectively. and a method of adjusting the temperature and pressure during polymerization. The production ratio of the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21 depends on the polymerization time in the first step and the second step, the size of the polymerization tank, the amount of polymer retained in the polymerization tank, the polymerization It can be controlled by temperature, polymerization pressure and the like. In addition, if necessary, drying may be performed at a temperature below the melting point of polypropylene in order to remove residual solvent of polypropylene and ultra-low molecular weight oligomers by-produced during production. Examples of drying methods include those described in JP-A-55-75410 and JP-A-2565753.

The melt flow rate of the propylene-based polymer composition (A) as described above, measured at 230° C. and a load of 2.16 kg, is preferably 0.00, from the viewpoint of improving processability and sanitation of the film. 001 g/10 min to 10 g/10 min, more preferably 0.01 g/10 min to 10 g/10 min, still more preferably 0.01 g/10 min to 5 g/10 min.

The numerical value of the melt flow rate can be changed by changing the molecular weight of the propylene-based polymer. Also, the melt flow rate can be determined by the method described in the examples below.

The film according to the present embodiment may contain an ethylene-based polymer (B) together with the propylene-based polymer described above as at least two types of olefin-based polymers. The ethylene-based polymer (B) is a polymer containing more than 50% by mass of monomer units derived from ethylene, and may be an ethylene homopolymer or an ethylene-based copolymer.

In such a case, the content of the propylene-based polymer composition (A) is preferably 70% by mass with respect to the total 100% by mass of the propylene-based polymer composition (A) and the ethylene-based polymer (B). 98 mass %, more preferably 75 mass % to 95 mass %, and still more preferably 80 mass % to 95 mass %. Further, the content of the ethylene polymer (B) is preferably 2% by mass to 30% by mass with respect to the total 100% by mass of the propylene polymer composition (A) and the ethylene polymer (B). , more preferably 5% by mass to 30% by mass, still more preferably 5% by mass to 25% by mass.

Examples of the ethylene-based polymer (B) include ethylene-α-olefin copolymers. The ethylene-α-olefin copolymer contains monomer units derived from ethylene and monomer units derived from an α-olefin having 4 to 12 carbon atoms (preferably 4 to 8 carbon atoms). The content of monomer units derived from ethylene in the ethylene-α-olefin copolymer is preferably 70% by mass to 95% by mass, more preferably 75% by mass to 95% by mass, and still more preferably. is 80% by mass to 95% by mass. In addition, the content of monomer units derived from α-olefins having 4 to 12 carbon atoms (preferably 4 to 8 carbon atoms) in the ethylene-α-olefin copolymer is preferably from 5% by mass to It is 30 mass %, more preferably 5 mass % to 25 mass %, still more preferably 5 mass % to 20 mass %. Examples of α-olefins having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene, 4 -methyl-1-hexene and the like. A monomer unit derived from an α-olefin having 4 to 12 carbon atoms is a monomer unit derived from a single α-olefin, or a monomer derived from two or more α-olefins. It may be a unit. The α-olefin having 4 to 12 carbon atoms is preferably 1-hexene from the viewpoint of improving the heat seal strength.

The density of the ethylene-α-olefin copolymer is preferably 850 kg/m ³ to 950 kg/m ³ , more preferably 850 kg/m ³ to 930 kg/m ³ , still more preferably 880 kg/m ³ to 930 kg. / ^m3 . When the density of the ethylene-α-olefin copolymer is 850 kg/m ³ or more, a film having excellent rigidity can be obtained, and when it is 950 kg/m ³ or less, excellent bag breakage resistance can be obtained. you can get the film.

The melt flow rate of the ethylene-α-olefin copolymer measured at 190° C. and a load of 2.16 kg is preferably 0.1 g/10 minutes to 50 g/10 minutes, more preferably 0.1 g/10 minutes. 10 g/10 minutes, more preferably 1 g/10 minutes to 5 g/10 minutes.

The numerical value of the melt flow rate can be changed by changing the molecular weight of the ethylene-α-olefin copolymer. Also, the melt flow rate can be determined by the method described in the examples below.

The molecular weight distribution of the ethylene-α-olefin copolymer is preferably 1 or more and 5 or less, more preferably 1 or more and 4 or less, and still more preferably 2 or more and 4 or less. When the molecular weight distribution of the ethylene-α-olefin copolymer is 1 or more, the extrusion load is reduced and processability is improved. In addition, when the molecular weight distribution of the ethylene-α-olefin copolymer is 5 or less, a film having excellent bag breakage resistance can be obtained. Here, the "molecular weight distribution" means the number average molecular weight (Mw) of the weight average molecular weight (Mw) measured under the following conditions using gel permeation chromatography (hereinafter sometimes referred to as "GPC"). Mn) is the ratio (Mw/Mn). The baselines on the chromatogram are points of stable horizontal regions with retention times well short of the appearance of sample elution peaks, and stable horizontal regions with retention times well above the observed solvent elution peaks. A straight line formed by connecting the points of

Apparatus: Waters 150C manufactured by Waters
Separation column: TOSOH TSK-GEL GMH6-HT
Measurement temperature: 140°C
Carrier: ortho-dichlorobenzene Flow rate: 1.0 mL/min Injection volume: 500 μL
Detector: Differential refraction Molecular weight standard substance: Standard polystyrene

As a method for adjusting the molecular weight distribution of the ethylene-α-olefin copolymer to the above range, for example, using a metallocene catalyst, ethylene and α-olefin are copolymerized to obtain the density of the ethylene-α-olefin copolymer. is 850 kg/m ³ to 950 kg/m ³ .

Ethylene-α-olefin copolymers can be produced, for example, using metallocene catalysts. The metallocene catalyst is, for example, an olefin polymerization catalyst using a transition metal compound having a group having a cyclopentadiene type anion skeleton (hereinafter also referred to as "metallocene transition metal compound").

Examples of metallocene transition metal compounds include compounds represented by the following formula (X).

MLaXn-a (X)

(In the formula,
M is a transition metal atom of Group 4 or the lanthanide series of the Periodic Table of the Elements.
L is a group having a cyclopentadiene type anion skeleton or a group containing a hetero atom, at least one of which is a group having a cyclopentadiene type anion skeleton. A plurality of Ls may be crosslinked with each other.
X is a halogen atom, a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.
n represents the valence of the transition metal atom.
a is an integer that satisfies 0 < a ≤ n)

Examples of metallocene transition metal compounds represented by the above formula include bis(1,3-n-butylmethylcyclopentadienyl)zirconium dichloride and bis(1,3-n-propylmethylcyclopentadienyl). Zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, bis(1,3-diethylcyclopentadienyl)zirconium dichloride, ethylene bis(indenyl) ) zirconium dichloride, ethylenebis(4-methyl-1-indenyl)zirconium dichloride, ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride and the like.

The above metallocene-based transition metal compound is preferably used in contact with an activating co-catalyst. Examples of the activating co-catalyst include an alumoxane compound and an activating co-catalyst in which an organoaluminum compound and a boron compound such as trityl borate or anilinium borate are used in combination. In addition, it may be used in combination with particulate carriers including inorganic carriers such as SiO ₂ and Al ₂ O ₃ and organic carriers such as polymers such as ethylene and styrene.

When the film according to the present embodiment contains the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21, the propylene-based polymer A-1, preferably 60% by mass to 95% by mass, more preferably 65% by mass to 95% by mass, still more preferably 65% by mass to 90% by mass, and the above propylene-ethylene copolymer A-21 , preferably 5% to 40% by mass, more preferably 5% to 35% by mass, even more preferably 10% to 35% by mass.

The film according to the present embodiment comprises the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21, and an ethylene-α-olefin copolymer as the ethylene-based polymer (B). , the propylene-based polymer A-1 is preferably 40% to 90% by mass, more preferably 40% to 85% by mass, and still more preferably 45% by mass, based on the total mass of all polymers in the film. % to 85% by mass, and the propylene-ethylene copolymer A-21 is preferably 5% to 40% by mass, more preferably 5% to 35% by mass, still more preferably 10% to 35% by mass preferably 5% to 30% by mass, more preferably 5% to 25% by mass, still more preferably 5% to 20% by mass, of the ethylene-α-olefin copolymer.

Further, the film according to the present embodiment includes the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21, and an ethylene-α-olefin copolymer as the ethylene-based polymer (B). propylene-based polymer A-1 and propylene-ethylene with respect to the total mass of propylene-based polymer A-1, propylene-ethylene copolymer A-21 and ethylene-α-olefin copolymer. The total weight ratio with the copolymer A-21 is preferably 70% to 95% by weight, more preferably 75% to 95% by weight, still more preferably 75% to 93% by weight. When the ratio of the total mass of the propylene-based polymer A-1 and the propylene-ethylene copolymer A-21 is within the above range, a film having good heat sealability can be obtained.

The film according to the present embodiment may further contain a phosphate ester metal salt-based nucleating agent. The content of the phosphate ester metal salt-based nucleating agent in such a film is preferably 100-10000 ppm, more preferably 100-5000 ppm, still more preferably 500-5000 ppm.

Examples of the phosphate metal salt-based nucleating agent include aromatic phosphate metal salts and the like. Specifically, sodium-bis(4-t-butylphenyl)phosphate, sodium-bis(4-methylphenyl)phosphate, sodium-bis(4-ethylphenyl)phosphate, sodium-bis(4-i -propylphenyl)phosphate, sodium-bis(4-t-octylphenyl)phosphate, potassium-bis(4-t-butylphenyl)phosphate, calcium-bis(4-t-butylphenyl)phosphate, magnesium -bis(4-t-butylphenyl) phosphate, lithium-bis(4-t-butylphenyl) phosphate, aluminum-bis(4-t-butylphenyl) phosphate, sodium-2,2'-methylene- Bis(4,6-di-t-butylphenyl) phosphate, sodium-2,2'-ethylidene-bis(4,6-di-t-butylphenyl) phosphate, lithium-2,2'-methylene- Bis(4,6-di-t-butylphenyl) phosphate, lithium-2,2'-ethylidene-bis(4,6-di-t-butylphenyl) phosphate, sodium-2,2'-ethylidene- Bis(4-i-propyl-6-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis(4-methyl-6-t-butylphenyl) phosphate, lithium-2,2'- methylene-bis(4-ethyl-6-t-butylphenyl)phosphate, calcium-bis[2,2′-thiobis(4-methyl-6-t-butylphenyl)phosphate], calcium-bis[2, 2′-thiobis(4-ethyl-6-t-butylphenyl)phosphate], calcium-bis[2,2′-thiobis-(4,6-di-t-butylphenyl)phosphate], magnesium-bis [2,2′-thiobis(4,6-di-t-butylphenyl)phosphate], magnesium-bis[2,2′-thiobis-(4-t-octylphenyl)phosphate], sodium-2, 2'-butylidene-bis(4,6-di-methylphenyl) phosphate, sodium-2,2'-butylidene-bis(4,6-di-t-butylphenyl) phosphate, sodium-2,2' -t-octylmethylene-bis(4,6-di-methylphenyl) phosphate, sodium-2,2'-t-octylmethylene-bis(4,6-di-t-butylphenyl l) phosphate, calcium-bis[2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate], magnesium-bis[2,2′-methylene-bis(4,6- di-t-butylphenyl)phosphate], barium-bis[2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate], sodium-2,2′-methylene-bis( 4-methyl-6-t-butylphenyl)phosphate, sodium-2,2'-methylene-bis(4-ethyl-6-t-butylphenyl)phosphate, sodium-(4,4'-dimethyl-5 ,6'-di-t-butyl-2,2'-biphenyl)phosphate, calcium-bis[(4,4-'dimethyl-6,6'-di-t-butyl-2,2'-biphenyl) phosphate], sodium-2,2′-ethylidene-bis(4-m-butyl-6-t-butylphenyl)phosphate, sodium-2,2′-methylene-bis(4,6-di-methylphenyl ) phosphate, sodium-2,2′-methylene-bis(4,6-di-ethylphenyl) phosphate, potassium-2,2′-ethylidene-bis(4,6-di-t-butylphenyl) phosphate phosphate, calcium-bis[2,2′-ethylidene-bis(4,6-di-t-butylphenyl)phosphate], magnesium-bis[2,2′-ethylidene-bis(4,6-di-t -butylphenyl)phosphate], barium-bis[2,2-'ethylidene-bis(4,6-di-t-butylphenyl)phosphate], aluminum-tris[2,2'-methylene-bis(4 ,6-di-t-butylphenyl)phosphate] and aluminum-tris[2,2′-ethylidene-bis(4,6-di-t-butylphenyl)phosphate] and mixtures of two or more thereof. can do. Especially preferred is sodium-2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate.

The film according to this embodiment may contain additives and other resins as necessary. Examples of additives include antioxidants, neutralizers, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, adhesives, antifogging agents, antiblocking agents, melt flow rate modifiers, and the like. Examples of antioxidants include phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like, and have both a phenol-based antioxidant mechanism and a phosphorus-based antioxidant mechanism in one molecule. Composite antioxidants having units can also be used. Other resins include elastomers such as styrene-based copolymer rubber obtained by hydrogenating styrene-butadiene-styrene copolymers and styrene-isoprene-styrene copolymers.

The method for producing a film configured as described above includes a melt-kneading step of melt-kneading a mixture containing at least two kinds of propylene-based polymers, an ethylene-based polymer, and a phosphoric acid ester metal salt-based nucleating agent. Prepare. In addition, the method for producing such a film includes an extrusion step of extruding the kneaded product obtained in the melt-kneading step into a sheet, and cooling the sheet-like kneaded product obtained in the extrusion step by pressing it against a cooling roll with gas blown from the air chamber. and a cooling step. Furthermore, such a method for producing a film includes a film-forming step of forming a sheet-like kneaded material into a film.

In the melt-kneading step, for example, the propylene-based polymer composition (A), the ethylene-based polymer (B), and preferably the propylene-based polymer composition (C) may be melt-kneaded. good. Further, the melt-kneading step is preferably performed by adding the various additives described above.

The melt-kneading step can be performed using a conventionally known method and apparatus. For example, the above materials (for example, pellets) are mixed using a mixing device such as a Henschel mixer, a ribbon blender, or a tumble mixer, and then melted and kneaded. Alternatively, after obtaining a homogeneous mixture by continuously supplying each of the above materials at a constant rate using a metering feeder, the mixture is extruded with a single screw or two or more screws, Banbury A method of melt-kneading using a mixer, a roll-type kneader, or the like can be mentioned. The melt-kneading temperature is preferably 190°C to 320°C, more preferably 210°C to 280°C.

The extrusion process can be performed using conventionally known methods and devices. For example, a T-die method, a tubular method, and the like can be mentioned, and the T-die method is preferred.

An air chamber used in the cooling process is installed close to the chill roll. Also, the air chamber is a box-structured device having an opening at a portion facing the cooling roll. A conventionally known device can be used as the air chamber. The air chamber is configured to receive gas supplied from a blower connected by a duct to raise the air pressure in the internal space, and to blow out the gas from the opening with an air volume and air pressure corresponding to the air pressure. As a result, the sheet-like kneaded material extruded from the T-die by the gas blown out from the air chamber is pressed against the cooling roll and brought into close contact therewith. The gas introduced into the air chamber includes, for example, air, nitrogen, carbon dioxide gas, and the like. Also, the temperature of the gas can be, for example, preferably 10.degree. C. to 50.degree.

The cooling step is performed by adjusting the amount of gas blown out from the air chamber so that the gas pressure in the air chamber is 50 Pa to 300 Pa, preferably 50 Pa to 250 Pa, more preferably 100 Pa to 250 Pa. In the cooling step, a sheet-like kneaded material is supplied between the air chamber and the cooling roll. Then, gas is blown from the air chamber to the sheet-like kneaded material to bring the sheet-like kneaded material into close contact with the cooling roll.

The air chamber has an opening (gas outlet) for blowing out gas in the horizontal direction, and the gas outlet is arranged to the side of the cooling roll and away from the cooling roll. The shortest distance between the gas outlet and the cooling roll is preferably 0.01 cm to 5 cm, more preferably 0.01 cm to 1 cm in the horizontal direction. In addition, the width of the opening of the air chamber (gas outlet) is set to be wider than the width of the sheet-like kneaded material (that is, the width of the blown air flow is wider than the sheet-like kneaded material). ). Thereby, the sheet-like kneaded material can be uniformly pressed against the cooling roll.

The surface temperature of the cooling roll is preferably 20°C to 80°C, more preferably 20°C to 70°C.

The film-forming step may be performed while the sheet-like kneaded material obtained in the extrusion step is in contact with a cooling roll (that is, it may be performed at the same time as the cooling step), or may be performed after the cooling step. When the film-forming process is performed after the cooling process, for example, the sheet-like kneaded material after the cooling process may be sandwiched between nip rolls to form a film having a predetermined thickness.

The film according to this embodiment can be used as a sealant layer of a multilayer film. A film forming another layer laminated on such a sealant layer is not particularly limited. Examples thereof include barrier films such as oriented nylon film, aluminum foil and polyvinylidene chloride film, and transferable films such as nylon film, polypropylene biaxially oriented film and polyethylene terephthalate film. Examples of methods for laminating films include a dry lamination method and an extrusion lamination method.

The thickness of the film according to this embodiment is preferably 5 to 500 μm, more preferably 30 to 150 μm.

A multilayer film having the film according to the present embodiment as a sealant can be used, for example, in packaging applications for packaging articles such as foods, fibers, and miscellaneous goods. For example, a multilayer film can be used as a material for forming packaging bags, preferably as a material for packaging bags for retort food.

The film according to the present embodiment may be subjected to surface treatment such as corona discharge treatment, flame treatment, plasma treatment, ozone treatment, etc., by a method generally employed industrially.

As described above, according to the present embodiment, it is possible to provide a film having bag breakage resistance and relatively excellent cuttability, and to provide a method for producing such a film.

That is, the film according to the present embodiment has a sea-island phase separation structure composed of a continuous phase and a discontinuous phase by at least two kinds of olefin-based polymers, and the MD direction of the film determined by wide-angle X-ray scattering measurement. When the degree of orientation is within the above range, the film has bag-breakage resistance and relatively excellent easy-to-cut properties.

In addition, the film according to the present embodiment satisfies the above formulas (1) and (2), so that it has bag breakage resistance and is excellent in ease of cutting.

Moreover, since the film according to the present embodiment contains the propylene-based polymer composition (A), it is possible to obtain a film that is more excellent in bag breakage resistance.

In addition, the film according to the present embodiment contains the propylene-based polymer composition (A) and the ethylene-based polymer (B) in the above ratio, so that a film having more excellent bag breakage resistance can be obtained. .

In addition, the film according to the present embodiment contains the phosphate ester metal salt-based nucleating agent in the above ratio, so that a film having excellent bag-breaking resistance and excellent easy-to-cut properties can be obtained.

In addition, the film according to the present embodiment contains the propylene-based polymer composition (C) that satisfies the above formula (3) in the above ratio, so that the film is excellent in bag breakage resistance and easy to cut. Obtainable.

In addition, in the method for producing a film according to the present embodiment, in the cooling step, by setting the gas pressure in the air chamber within the above range, a film having bag breakage resistance and relatively excellent easy-to-cut properties is produced. can.

It should be noted that the film and the method for manufacturing the film according to the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. In addition, the configurations, methods, etc., of the multiple embodiments described above and below may be arbitrarily adopted and combined (the configurations, methods, etc., according to one embodiment may be applied to the configurations, methods, etc., according to other embodiments). of course).

Measured values of each item in Examples and Comparative Examples were measured by the following methods.

The contents of the propylene-based polymer and the propylene-ethylene copolymer contained in the propylene-based polymer composition are obtained from the mass balance during the polymerization of each.

The content of the ethylene-derived monomer units contained in the propylene-ethylene copolymer contained in the propylene-based polymer composition is determined by measuring the IR spectrum of the entire propylene-based polymer composition and performing polymer analysis. It is calculated by the following formula (4) in accordance with "(ii) Method for block copolymer" described on page 616 of Handbook (published by Kinokuniya Shoten, 1995). Here, ET, EA and EB in the following formula (4) are respectively the content of monomer units derived from ethylene in the entire propylene-based polymer composition and the amount of monomers derived from ethylene in the propylene-based polymer. Indicates the content of the body unit and the content of the ethylene-derived monomer units in the propylene-ethylene copolymer, and PA and PB indicate the content of the propylene-based polymer and the propylene-ethylene copolymer, respectively. .

EB=(ET−EA×PA)/PB (4)

(1) Melt flow rate (MFR, unit: g/10 minutes)
The melt flow rate of the propylene-based polymer composition was measured at a temperature of 230° C. and a load of 2.16 kg according to the method specified in JIS K7210.
The melt flow rate of the ethylene-based polymer was measured at a temperature of 190°C and a load of 2.16 kg according to the method specified in JIS K7210.

(2) Amount of cold xylene solubles (CXS, unit: % by mass)
After dissolving 0.5 g of the propylene-based polymer composition in 100 mL of boiling xylene, the obtained solution was cooled to 0° C. and allowed to stand at the same temperature for 0.5 hours. After that, the xylene solution was heated to 20° C. and stirred at the same temperature for 1 hour. After filtering the resulting mixture into a precipitate and a solution, the propylene-based polymer in the solution was quantified by liquid chromatography to measure the amount of cold xylene solubles. The measurement conditions for liquid chromatography are as follows.

Column: SHODEX GPC KF-801
Eluent: Tetrahydrofuran Sample injection volume: 100 μL
Flow rate: 1.5 mL/min Detector: Differential refractometer

(3) Intrinsic viscosity ([η], unit: dL/g)
The intrinsic viscosity of the propylene-based polymer composition was measured in tetralin (1,2,3,4-tetrahydronaphthalene) at 135° C. using an Ubbelohde viscometer.
Intrinsic viscosity [η] of the cold xylene-insoluble part of the propylene-based polymer composition _CXIS is the intrinsic viscosity [η] of the propylene-based polymer composition and the intrinsic viscosity [η ] Calculated using the following formula (5) from _CXS and weight.

[η] _CXIS = ([η] x 100-[η] _CXS x W _CXS )/W _CXIS (5)

(In the formula,
[η] _CXIS indicates the intrinsic viscosity (dL/g) of the cold xylene-insoluble portion of the propylene-based polymer composition.
[η] represents the intrinsic viscosity (dL/g) of the propylene-based polymer composition.
[η] _CXS indicates the intrinsic viscosity (dL/g) of the cold xylene soluble portion of the propylene-based polymer composition.
W _CXS indicates the content (% by mass) of cold xylene solubles in the propylene-based polymer composition.
W _CXIS indicates the content (% by mass) of the cold xylene-insoluble portion of the propylene-based polymer composition. )

(4) Melt tension (MT, unit: mN)
Using a melt tension measuring machine manufactured by Toyo Seiki Co., Ltd., the melt tension of the propylene-based polymer composition was measured under the following conditions.

Specifically, an orifice with a length of 8.00 mm and an inner diameter of 2.10 mm was attached to a cylinder with an inner diameter of 9.55 mm. After that, the cylinder was filled with the propylene-based polymer composition, a piston was inserted into the cylinder, and the cylinder was preheated at 190° C. for 5 minutes to sufficiently melt the propylene-based polymer composition. Thereafter, the piston is lowered at a speed of 5.7 mm/min, and the propylene-based polymer composition melted and extruded from the orifice at 0.32 g/min is taken up at 15.7 m/min. The tension (mN) acting on the film was measured with a tension detector and taken as the melt tension.

(5) Observation of Sea-island Phase Separation Structure Observation of the sea-island phase separation structure in the single-layer film was performed using a transmission electron microscope. After embedding the film in resin and then dyeing it with an aqueous ruthenium tetroxide solution, a cross section determined by the MD and ND directions of the film was cut out with a cryomicrotome to prepare an ultrathin sample with a thickness of 200 nm or less. However, the MD direction is the flow direction of the film during the formation of the single-layer film, and the ND direction is the thickness direction of the film. After placing the ultrathin sample on an observation mesh, a cross-sectional image was taken with a transmission electron microscope (H-7650, manufactured by Hitachi High-Tech Co., Ltd.) under the conditions of an acceleration voltage of 100 kV and an observation magnification of 5000 times.

(6) Three-dimensional refractive index measurement A test piece having a width of about 50 mm (TD direction) and a length of about 40 mm (MD direction) was cut out from the single layer film. However, the TD direction is the width direction of the film when the single layer film is formed, and the MD direction is the flow direction of the film when the single layer film is formed. Three-dimensional refractive index measurement was performed on the obtained test piece using a measuring device KOBRA-WR (manufactured by Oji Scientific Instruments Co., Ltd.) and software KOBRA-RE. The test piece was set in the measuring device so that the MD direction coincided with the 0 degree direction on the angle reference of the measuring device KOBRA-WR. The retardation value R (0) (nm) measured by entering light with a wavelength of 589.3 nm from the thickness direction of the film, and the wavelength from the direction inclined 30 ° with respect to the thickness direction of the film with the slow axis as the tilt axis A retardation value R(30) (nm) was obtained by measuring the incident light of 589.3 nm. From the obtained R (0) and R (30) and the film thickness d (nm), with the following formula (12) as a constraint condition, the slow axis refractive index Nx that satisfies the following formulas (6) to (11), The refractive index Ny of the fast axis and the refractive index Nz in the thickness direction of the film were calculated. where N' is the refractive index in the plane of incidence when the incident angle is 30°, β1 is the refraction angle with respect to the refractive index N' when the incident angle is 30°, and β2 is the refraction with respect to the refractive index Nx when the incident angle is 30°. is a corner. Furthermore, the angle θ (°) formed by the MD direction of the film and the slow axis was obtained.

Nx−Ny=R(0)/d (6)
Nx−N′=R(30)×cosβ/d (7)
N′=Ny×Nz/(Ny ² ×sin ² β1+Nz ² ×cos ² β1) ^1/2 (8)
however,
β=(β1+β2)/2 (9)
β1=sin ⁻¹ (sin30°/N′) (10)
β2=sin ⁻¹ (sin30°/Nx) (11)
(Nx+Ny+Nz)/3=1.4915 (12)

(7) Wide-angle X-ray scattering measurement A plurality of test pieces having a width of about 2 cm (TD direction) and a length of about 2 cm (MD direction) were cut out from the single-layer film. The TD direction is the width direction of the film when the single layer film is formed, and the MD direction is the flow direction of the film when the single layer film is formed. A test piece for measurement was prepared by stacking six test pieces such that the MD directions of the test pieces were aligned. Wide-angle X-ray scattering measurements were performed on the obtained test pieces for measurement under the following conditions.

・Model: Rigaku Nano Viewer
・Tube: Cu-Kα
・Detector: PILATUS 100k
・Exposure time: 300 seconds ・Tube voltage: 40 kV
・Tube current: 20mA
・Beam diameter: 0.25 mmφ

The transmission intensity I ₀ and the scattering intensity I _Air were obtained in a state in which the camera length, which is the distance from the X-ray source to the camera, was kept constant and no test piece for measurement was set. The surface of the test piece for measurement was set so that the X-rays were incident perpendicularly thereto, and the transmission intensity It and the scattered _diffraction intensity I _s were measured. _Using the ratio of I ₀ and It as a correction ratio R, air scattering correction was performed using the following equations (13) and (14) from the measured scattered diffraction intensity I _s . Let the corrected scattered diffraction intensity be _Ic .

R=I _t /I ₀ (13)
_Ic = _Is -R×I _Air (14)

From the X-ray diffraction image obtained by the measurement, the _Ic of the diffraction peak of the (040) plane of the polypropylene crystal was plotted in the circumferential direction every 0.2° to create an azimuth angle profile. Using the peak appearing on the TD side of the test piece for measurement, the height from the bottom to the top of the peak was taken as the peak height, and the half width W, which is the peak width at which the peak height is halved, was obtained. The sum of the half-value widths of the peaks appearing on the TD side was defined as ΣW, and the degree of orientation F (%) in the MD was obtained using the following formula (15).

F=(360−ΣW)×100/360 (15)

(8) Evaluation of Tear Strength Based on JIS K7128-2 (Elmendorf tear method), the tear strength of the monolayer film was measured under the following conditions.
A test piece with a width of 76 mm (TD direction) and a length of 63 mm (MD direction) was cut from the monolayer film. The TD direction is the width direction of the film when the single layer film is formed, and the MD direction is the flow direction of the film when the single layer film is formed. After the obtained test piece was installed in a temperature-controlled room at 23° C., a cut of 20 mm was made in the longitudinal direction from the edge of the width center. Next, the test piece was attached to a gripper of a digital Elmendorf tear tester (manufactured by Toyo Seiki Co., Ltd.) to measure the tear strength. The tear strength (N/mm) was obtained by dividing the numerical value (N) obtained by tearing by the thickness (mm) of the test piece.

(9) Evaluation of Falling Bag Strength A composite film was used in which a single layer film, a 7 μm thick aluminum foil, and a 12 μm thick polyethylene terephthalate film were laminated in the order described by the dry lamination method. Then, the single-layer film surface was folded inside using a standing pouch bag-making machine manufactured by Seibu Kikai Co., Ltd., and each of the three sides was heat-sealed three times at 240° C. for 0.5 seconds to prepare a packaging bag. After filling the resulting packaging bag with 160 g of water, the remaining side that was not heat-sealed was heat-sealed with an impulse sealer for 1.0 second to seal the water-filled packaging bag having a size of 150 mm long and 130 mm wide. was made. The water-filled packaging bag was conditioned at 5° C. for 24 hours and then tested by repeatedly dropping it from a height of 16 cm 20 times. Twelve bags each were tested, and the drop strength was evaluated by the total number of times the bag did not break. A score of 240 is given when no break occurs, and a score of 0 is given when the cover is broken all at once.

Components used in Examples and Comparative Examples are as follows.

[Propylene polymer composition (a-1)]
Using a Ziegler-Natta type catalyst, propylene is polymerized in the gas phase in the first step, and then propylene and ethylene are copolymerized in the gas phase in the second step to obtain a propylene homopolymer (a-11). and a propylene-ethylene copolymer (a-12) were obtained. The resulting propylene-based multistage polymer had a propylene homopolymer (a-11) content of 70% by mass and a propylene-ethylene copolymer (a-12) content of 30% by mass. The content of monomer units derived from ethylene in the propylene-ethylene copolymer (a-12) was 30% by mass. 0.005 parts by mass of calcium hydroxide, 0.075 parts by mass of Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.), and 0.075 parts by mass of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) are added to 100 parts by mass of the obtained propylene-based multistage polymer. 03 parts by mass were mixed and melt-kneaded to obtain a propylene-based polymer composition (a-1). The propylene-based polymer composition (A-1) has a cold xylene-insoluble content of 81% by mass, an intrinsic viscosity ([η] _CXIS ) of 1.82 dl/g, and a cold xylene-soluble content of 19. % by weight, its intrinsic viscosity ([η] _CXS ) was 2.95 dl/g, and its melt flow rate was 3.1 g/10 min.

[Propylene polymer composition (a-2)]
Using a Ziegler-Natta type catalyst, propylene is polymerized in the gas phase in the first step, and then propylene and ethylene are copolymerized in the gas phase in the second step to obtain a propylene homopolymer (a-21). and a propylene-ethylene copolymer (a-22) were obtained. The resulting propylene-based multistage polymer had a propylene homopolymer (a-21) content of 84% by mass and a propylene-ethylene copolymer (a-22) content of 16% by mass. The content of monomer units derived from ethylene in the propylene-ethylene copolymer (a-22) was 40% by mass. 0.005 parts by mass of calcium hydroxide, 0.075 parts by mass of Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.), and 0.03 part by mass of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) for 100 parts by weight of the multistage propylene polymer obtained. After mixing parts by mass, they were melt-kneaded to obtain a propylene-based polymer composition (a-2). The propylene-based polymer composition (a-2) has a cold xylene-insoluble content of 90% by mass, an intrinsic viscosity ([η] _CXIS ) of 1.56 dl/g, and a cold xylene-soluble content of 10%. %, its intrinsic viscosity ([η] _CXS ) was 2.00 dl/g, and its melt flow rate was 7.0 g/10 min.

[Propylene polymer composition (a-3)]
Using a Ziegler-Natta type catalyst, propylene is polymerized in the gas phase in the first step, and then propylene and ethylene are copolymerized in the gas phase in the second step to obtain a propylene homopolymer (a-31). and a propylene-ethylene copolymer (a-32) were obtained. The resulting propylene-based multistage polymer had a propylene homopolymer (a-31) content of 77% by mass and a propylene-ethylene copolymer (a-32) content of 23% by mass. The content of ethylene-derived monomer units in the propylene-ethylene copolymer (a-32) was 30% by mass. 0.005 parts by mass of calcium hydroxide, 0.075 parts by mass of Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.), and 0.075 parts by mass of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) are added to 100 parts by mass of the obtained propylene-based multistage polymer. 075 parts by mass were mixed and melt-kneaded to obtain a propylene-based polymer composition (a-3). The propylene-based polymer composition (a-3) has a cold xylene-insoluble content of 84% by mass, an intrinsic viscosity ([η] _CXIS ) of 1.93 dl/g, and a cold xylene-soluble content of 16. % by weight, its intrinsic viscosity ([η] _CXS ) was 3.03 dl/g, and its melt flow rate was 2.5 g/10 min.

[Ethylene polymer (b-1)]
An ethylene-butene copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumikasen L GA401) was used. The melt flow rate was ^3.0 g/10 min and the density was 935 kg/m3.

[Ethylene polymer (b-2)]
An ethylene-butene copolymer (manufactured by Mitsui Chemicals, Inc., trade name: Toughmer A4085s) was used. The melt flow rate was ^3.6 g/10 min and the density was 885 kg/m3.

[Propylene polymer composition (c-1)]
Using a Ziegler-Natta type catalyst, a propylene homopolymer (c-11) having an intrinsic viscosity of 7.18 dl/g is produced in the first step, and an intrinsic viscosity of 0.85 dl/g is produced in the second step. A propylene homopolymer (c-12) was produced to obtain a propylene-based multistage polymer. The resulting propylene-based multistage polymer contained 19% by mass of the propylene homopolymer (c-11) produced in the first step and the propylene homopolymer (c-12) produced in the second step. was 81% by mass. 0.050 parts by mass of calcium stearate, 0.2 parts by mass of Irganox 1010 (manufactured by BASF), and 0.025 parts by mass of Irgafos 168 (manufactured by BASF) were mixed with 100 parts by weight of this propylene-based multistage polymer. Thereafter, the mixture was melt-kneaded to obtain a propylene-based polymer composition (c-1). The propylene-based polymer composition (c-1) had a melt flow rate of 8.9 g/10 minutes and a melt tension of 25.7 mN.

[Composition (d) containing one type of propylene-based polymer]
Propylene was polymerized using a Ziegler-Natta type catalyst to obtain a propylene homopolymer. 0.002 parts by weight of calcium hydroxide and 0.15 parts by weight of Irganox 1010 (manufactured by BASF) are mixed with 100 parts by weight of the obtained propylene homopolymer, and then melt-kneaded to obtain a propylene-based polymer. A composition (d) containing one of The resulting composition (d) had a melt flow rate of 8.0 g/10 minutes.

[Phosphate ester metal salt nucleating agent masterbatch (MB)]
Propylene was polymerized using a Ziegler-Natta type catalyst to obtain a propylene homopolymer. 94% by mass of the resulting propylene homopolymer and ADEKA STAB NA-11 (sodium-2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate, which is a metal phosphate ester, manufactured by the company ADEKA) was mixed with 6% by mass. With respect to 100 parts by mass of the obtained mixture, 0.01 part by mass of hydrotalcite, 0.1 part by mass of Irganox 1010 (manufactured by BASF), and 0.05 part by mass of Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.) are mixed. After that, the mixture was melt-kneaded to obtain a phosphate ester metal salt nucleating agent masterbatch (MB).

[Example 1]
42% by mass of propylene-based polymer composition (a-1), 45% by mass of propylene-based polymer composition (a-2), 8% by mass of ethylene-based polymer (b-1), and phosphate ester metal salt nucleation 5% by mass of the agent masterbatch (MB) was pellet blended. The obtained mixture was melt-kneaded by three extruders, then the obtained molten mixture was united and introduced into a feed block type T-die (die width 1250 mm, lip opening 0.8 mm). , melt extrusion was performed at a die temperature of 240°C. After adjusting the air volume of the air chamber so that the air pressure in the air chamber box is 200 Pa, the extruded molten film is cooled and solidified by a chill roll (cooling roll) rotating at 50 m/min and having a cooling temperature of 50°C. A monolayer film with a thickness of 70 μm was obtained. The obtained monolayer film had a sea-island type phase separation structure. The ingredients contained in the monolayer film are shown in Tables 1 and 2.

Three-dimensional refractive index measurement, wide-angle X-ray scattering measurement, and tear strength evaluation were performed on the resulting single-layer film. Also, a composite film produced using the obtained monolayer film was evaluated for falling bag strength. Each evaluation result is shown in Table 3.

[Example 2]
85% by mass of the propylene-based polymer composition (a-3), 10% by mass of the ethylene-based polymer (b-2), and 5% by mass of the phosphate ester metal salt nucleating agent masterbatch (MB) are pellet-blended. A monolayer film was produced and evaluated in the same manner as in Example 1, except that the obtained mixture was used. The obtained monolayer film had a sea-island type phase separation structure. Table 1 shows the ingredients contained in the monolayer film. Tables 2 and 3 show each evaluation result.

[Example 3]
Propylene-based polymer composition (a-3) 75% by mass, propylene-based polymer composition (c) 10% by mass, ethylene-based polymer (b-2) 10% by mass, and phosphate ester metal salt nucleating agent master A single layer film was produced and evaluated in the same manner as in Example 1, except that a pellet blended mixture of 5% by mass of batch (MB) was used. The obtained monolayer film had a sea-island type phase separation structure. Table 1 shows the ingredients contained in the monolayer film. Tables 2 and 3 show each evaluation result.

[Comparative Example 1]
A single layer film was produced and evaluated in the same manner as in Example 1, except that the air volume in the air chamber box was adjusted so that the air pressure in the air chamber box was 500 Pa. The obtained monolayer film had a sea-island type phase separation structure. Table 1 shows the ingredients contained in the monolayer film. Tables 2 and 3 show each evaluation result.

[Comparative Example 2]
A monolayer film was produced and evaluated in the same manner as in Example 1, except that only 100% by mass of the propylene-based polymer composition (a-3) was used. The obtained monolayer film had a sea-island type phase separation structure. Table 1 shows the ingredients contained in the monolayer film. Tables 2 and 3 show each evaluation result.

[Comparative Example 3]
A single layer film was produced in the same manner as in Example 1, except that a mixture obtained by pellet blending 90% by mass of the propylene polymer composition (a-3) and 10% by mass of the ethylene polymer (b-2) was used. was produced and evaluated. The obtained monolayer film had a sea-island type phase separation structure. Table 1 shows the ingredients contained in the monolayer film. Tables 2 and 3 show each evaluation result.

[Comparative Example 4]
Same as Example 1 except that a mixture obtained by pellet blending 95% by weight of the composition (d) containing one type of propylene-based polymer and 5% by weight of the phosphate ester metal salt nucleating agent masterbatch (MB) was used. Then, a single layer film was produced and evaluated. The monolayer film obtained did not have a sea-island phase separation structure. Table 1 shows the ingredients contained in the monolayer film. Tables 2 and 3 show each evaluation result.

Claims (7)

A film containing at least two olefinic polymers,
At least two kinds of olefin-based polymers form a sea-island phase separation structure consisting of a continuous phase and a discontinuous phase,
The degree of orientation of the film in the MD direction determined by wide-angle X-ray scattering measurement is 76% or more.
the film. satisfying the following formulas (1) and (2),
The film of Claim 1.

(Nx×cos θ−Ny×cos θ)/d≧3.0×10 ⁻⁸ (1)
(Nx−(Ny+Nz)/2)/d≧3.4×10 ⁻⁸ (2)
(In the formula,
Nx represents the refractive index of the slow axis of the film determined by three-dimensional refractive index measurement.
Ny represents the refractive index of the fast axis of the film determined by three-dimensional refractive index measurement.
Nz indicates the refractive index in the thickness direction of the film determined by three-dimensional refractive index measurement.
θ indicates the angle (°) formed between the MD direction of the film and the slow axis determined by three-dimensional refractive index measurement.
d indicates the film thickness (nm). )
the at least two olefin-based polymers are at least two propylene-based polymers;
containing a propylene-based polymer composition (A) containing the at least two propylene-based polymers,
The propylene-based polymer composition (A) is
The content of the cold xylene soluble part is 5 to 25% by mass, the intrinsic viscosity [η] _CXS of the cold xylene soluble part is 1.5 to 3.5 dL / g,
The content of the cold xylene-insoluble part is 75 to 95% by mass, and the intrinsic viscosity [η] _CXIS of the cold xylene-insoluble part is 1.0 to 2.5 dL / g.
3. The film of claim 1 or 2. Furthermore, it contains an ethylene polymer (B),
The content of the propylene-based polymer composition (A) is 70% by mass to 98% by mass with respect to the total 100% by mass of the propylene-based polymer composition (A) and the ethylene-based polymer (B), The content of the ethylene polymer (B) is 2% by mass to 30% by mass,
4. The film of claim 3. Furthermore, containing 100 ppm to 10000 ppm of a phosphate ester metal salt-based nucleating agent,
The film according to any one of claims 1-4. the at least two olefin-based polymers are at least two propylene-based polymers;
5% to 30% by mass of the propylene-based polymer composition (C) containing the at least two propylene-based polymers,
The propylene-based polymer composition (C) satisfies the following formula (3):
The film according to any one of claims 1-5.

MT ^C >70×MFR ^C-1.1 (3)
(In the formula,
MTC indicates the melt tension (mN) measured at a temperature of 190° ^C and a take-up speed of 15.7 m/min.
MFR ^C indicates the melt flow rate (g/10 min) measured at a temperature of 230°C and a load of 2.16 kg. )
A method for producing the film according to any one of claims 1 to 6,
a melt-kneading step of melt-kneading a mixture containing at least two types of propylene-based polymers, an ethylene-based polymer, and a phosphoric acid ester metal salt-based nucleating agent;
an extrusion step of extruding the kneaded product obtained in the melt-kneading step into a sheet;
A cooling step in which the sheet-like kneaded product obtained in the extrusion step is cooled by pressing it against a cooling roll with gas blown from an air chamber;
A film forming step of forming a film by forming a sheet-like kneaded product,
In the cooling step, the air volume of the gas blown out from the air chamber is adjusted so that the gas pressure in the air chamber is 50 Pa to 300 Pa,
Film production method.