JP2000273202A - Polypropylene film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene film having a large heat shrinkage in the direction perpendicular to film flow, having an excellent adhesion of the film to an object to be packaged when being used for heat shrink packaging and not causing wrinkles and unevenness in shrinkage, excellent in automatic packaging aptitude and suitable for heat shrink packaging uses. SOLUTION: This polypropylene film is characterized by the following properties: having an amorphous orientation parameter [TD-AOP] of >=0.3 (preferably 0.32-0.38), defined as the product of a direction cosine <cos2ϕTD> by an amorphous fraction (1-χc) of molecular chains in the amorphous region of the polypropylene film in the cross direction; and having the crystallization degree of <=50% (preferably 25-45%).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel polypropylene film. Specifically, when a food container or the like is heat-shrink wrapped, a polypropylene film which has a large shrinkage ratio, has good adhesion to the container, does not generate wrinkles and shrinkage unevenness, and can be suitably used as a heat shrink wrapping film. About.

[0002]

2. Description of the Related Art Polypropylene films are widely used as packaging materials because of their excellent mechanical properties such as tensile strength and elongation, and optical properties such as transparency and gloss.

[0003] There are various forms of packaging, and among them, heat-shrinkable packaging using a heat-shrinkable polyolefin film such as polypropylene or polyethylene is widely used for packaging of containers for instant foods and the like.
In this heat shrink wrapping, for example, after wrapping the periphery of a container with a lid or the like with a heat shrink wrapping film and fixing the layered portion with an adhesive, an adhesive tape, fusion or the like, heat is applied to the heat shrink wrapping film. By adding the film, the film is shrunk in accordance with the shape of the container by heat, and the film is packed so as to be in close contact with the container to be packaged.

[0004] The polypropylene film conventionally used for the above packaging has a small heat shrinkage of several percent at a relatively low heating temperature of about 120 ° C., so that when the object to be wrapped or the like is heat shrink wrapped. In addition, there is a problem that the film does not sufficiently shrink, the film does not adhere to the container to be packaged, and wrinkles and shrinkage unevenness occur. Therefore, it cannot be used for heat shrink wrapping applications that require large heat shrinkage.

[0005] In particular, a film taken up by a roll is unwound in the direction of film flow (hereinafter referred to as MD).
And cut in a direction perpendicular to the MD (hereinafter abbreviated as TD) to form a long strip-shaped film 3 in the TD, and as shown in FIG. A case in which a so-called "band-wrapping package" is used in which a multi-layer body is hung so as to make a circuit around the packaged body made of the container 2 to fix the multilayer portion, and then heat shrink-wrapping is performed by a step of heating this. In conventional heat shrink wrapping films, the TD has a low heat shrinkage, so the "banding" after heating is loose and the film comes off the container, and the film has wrinkles and shrinkage unevenness. Phenomenon occurs. Such wrinkles and uneven shrinkage impair the appearance of the product to be packaged, thereby reducing the value of the product, or, in extreme cases, when the film is printed, the display is incomplete. Cause the problem of

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a TD having excellent heat shrinkage characteristics. For example, when a food container or the like is subjected to heat shrink wrapping, the film may come off from the container after heating, and wrinkles or shrinkage may occur. An object of the present invention is to provide a polypropylene film which does not generate unevenness and has excellent automatic packaging suitability.

[0007]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and found that the T
We have succeeded in developing a polypropylene film in which the amorphous part of D has a molecular chain orientation in a special range that is not found in conventional biaxially oriented polypropylene. Such a film has a very large TD heat shrinkage, Have been found to be excellent in heat shrinkage characteristics, and have completed the present invention.

That is, the present invention provides an amorphous orientation parameter (hereinafter, referred to as “TD”) in a direction (TD) perpendicular to the film flow direction.
[TD-AOP] is 0.3 or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the amorphous orientation parameter [TD-AOP]
It is an index indicating the degree and amount of TD orientation of the molecular chain of the amorphous part oriented in D. As shown in the following formula (1), the degree of orientation of the amorphous part of _TD <cos ² φ _TD > _a and it is determined by the product of the amorphous fraction (1-χ _c).

[0010] [TD-AOP] = <cos 2 φ TD> a × (1-χ c) (1) Similarly, amorphous orientation parameter of MD (hereinafter, [MD-A
OP] is an index indicating the degree and amount of MD orientation of the molecular chain of the amorphous part oriented in the MD of the polypropylene film, and as shown in the following formula (2), the amorphous part of the MD the degree of orientation is determined by the product of the <cos ² φ _{MD> a} and an amorphous fraction (1-χ _c).

[MD-AOP] = <cos ² φ _MD > _a × (1− _c ) (2) The degree of orientation of the above-mentioned amorphous part <cos ² φ _MD > _a and <cos ² φ _TD >
_a is an eye. Karakan et al. (I. Karacan et al.) [Polymer (Po
lymer), 34, 2691 (1993)], the refractive index n in the MD, TD, and thickness direction (hereinafter abbreviated as ND) of the film.
_{From MD} , n _TD , n _ND , the root mean square <cos ² φ _MD > _c and <cos ² φ _TD > _c of the direction cosine of the polypropylene crystal c-axis and MD and TD, and the volume crystal fraction νc, And (4).

[0012]

(Equation 1)

[0013]

(Equation 2)

Here, Δ _c ⁰ and Δ _a ⁰ are intrinsic birefringence of crystal and amorphous, and are described by R.A. Jay. Samwells (RJ
Samuels) [Journal of Applied Polymer
Science (Journal of Applied Polymer Science),
26,1383 (1981)] specific crystal provided by the birefringence Δ _c ⁰ = 0.0291, intrinsic birefringence Δ _a ⁰ = ⁰ in the amorphous regions.
060 was used.

The refractive indices n _MD , n _TD and n _ND can be measured by using a three-dimensional birefringence measuring device, an Abbe refractometer or the like.

The polypropylene crystal c-axis and M
For the root mean square <cos ² φ _MD > _c and <cos ² φ _TD > _c of the direction cosines with D and TD, the c-axis (molecular chain axis) of the polypropylene crystal is uniaxially oriented to the MD and TD of the polypropylene film. It is an index indicating the degree and can be obtained by the following method. That is, using an X-ray diffractometer equipped with a pole figure apparatus, a polypropylene crystal (11
The pole figure measurement of the 0) plane and the (040) plane is performed,
Root mean square <cos ² φ _{110, MD} > _c , <cos ² φ _{110, TD} > _{c for} the MD and TD of (110) and (040) planes,
And, <cos ² φ _{040 , MD} > _c and <cos ² φ _{040, TD} > _c are obtained.
Z. Wu. Wilchinski (ZWWilchins)
ky) According to the method of [Journal of Applied Physics, 31, 1969 (1960)], the crystal c-axis and MD are calculated by the formulas (5) and (6).
Root mean square <cos ² φ _MD > _c and <
cos ² φ _TD > _c is required.

<Cos ² φ _MD > _c = 1-1.099 <cos ² φ _{110, MD} > _c −0.901 <cos ² φ _{040, MD} > _c (5) <cos ² φ _TD > _c = 1-1.099 <cos _{^{2 φ 110, TD> c -}} 0.901 <cos 2 φ 040, TD> c (6) the above-mentioned volume crystalline fraction νc can be determined by the following method. Differential scanning calorimeter (hereinafter, DS)
C), the theoretical heat of fusion ΔH ₀ = 2 from the heat of fusion ΔH represented by the peak area of the crystal melting curve at the time of temperature rise measured in
The crystal fraction (weight crystal fraction) χ _c is determined from Eq. (7) using 01 (J / g).

Χ _c = ΔH / ΔH ₀ (7) where ν _c is G. Natta et al. [Anrew.Ch
em., 69,686 (1957)], the crystal density ρc of the polypropylene given by 0.935 g / cm ³ and the amorphous density ρ _a = 0.8
It calculated by Formula (8) using 57 g / cm ³ .

[0019] _{ν c = ρ a χ c /} {ρ a χ c + ρ c (1-χ c)} and (8), the amorphous fraction of the formula (1) and (2) (1-chi _c) is it can be obtained from the above crystalline fraction chi _c.

The polypropylene film of the present invention has a TD
Is characterized in that the amorphous orientation parameter ([TD-AOP]) is within a specific range shown below. In order to obtain a polypropylene film exhibiting excellent heat shrinkage properties with excellent TD, a film forming method by biaxial stretching is preferable. However, [TD-AOP] of the conventional biaxially stretched polypropylene film was at most about 0.26. And, the heat shrinkage of such a film is not satisfactory especially in the use of the film for heat shrink wrapping. On the other hand, the polypropylene film of the present invention has the above [TD-AOP] of 0.3.
This is an extremely high value. And the polypropylene film having such [TD-AOP] has high performance as a film for heat shrink wrapping.

That is, the [TD-AOP] of the polypropylene film of the present invention needs to be at least 0.3, preferably at least 0.32, and more preferably at least 0.32.
More preferably, it is 34 or more. [TD-AOP]
Is smaller than 0.3, the thermal shrinkage of the TD is small, and the film does not sufficiently adhere to the container to be packaged at the time of heat shrink wrapping, so that the film is detached from the container or wrinkles are preferably generated. Absent.

Further, heat shrink wrapping such as banding wrapping is generally performed by automatically sending out a film wound on a roll, cutting the film, and wrapping the object to be wrapped by an automatic wrapping machine. . For this reason, a film that is strong in the MD, which is the unwinding direction of the film, and the TD, which is the direction in which the film is wound around the container at the time of packaging, that is, a polypropylene film having a high tensile modulus of elasticity in the MD and TD, becomes loose or meandering during automatic packaging. This is more preferable because it does not cause any problems, such as being suitable for automatic packaging.

Therefore, considering that the thermal contraction rate of TD of the polypropylene film of the present invention is increased and the tensile modulus of MD and TD is increased, [TD-A
OP] is more preferably in the range of 0.32 to 0.38, and most preferably in the range of 0.34 to 0.36.

The polypropylene film of the present invention can sufficiently achieve the effects of the present invention if the amorphous orientation parameter [TD-AOP] of TD is within the range specified in the present invention. Taking into account the balance of physical properties such as the heat shrinkage and tensile elasticity of the film which affects the suitability for heat shrink wrapping and automatic wrapping, it is preferable to satisfy the following requirements.

The crystallinity of the polypropylene film of the present invention (the above crystal fraction 分_c × 100 (%)) is not particularly limited, but is 50% in order to increase the heat shrinkage of the polypropylene film. In order to further increase the heat shrinkage and increase the tensile elasticity, it is more preferably in the range of 25 to 45%, and more preferably in the range of 30 to 40%. Most preferably.

The preferred range of the crystallinity of the polypropylene film of the present invention is represented by the above-mentioned amorphous fraction (1- 率_c ).
0.5 or more, preferably in the range of 0.55 to 0.75, more preferably in the range of 0.6 to 0.7.

The degree of orientation <cos ² φ _TD > _a of the amorphous part of the TD of the polypropylene film of the present invention is not particularly limited, but the thermal shrinkage of the polypropylene film is increased and the tensile elasticity of the TD is increased. Taking into account that
It is preferably 0.4 or more. In some cases, if the strength of the container or the like to be packaged is low and easily deformed in heat shrink wrapping, a polypropylene film may be used.
If <cos ² φ _TD > _c is high, the shrinkage stress of the film at the time of heat shrinkage increases, which may cause problems such as deforming the container to be packaged.In consideration of such a point, <cos ² φ
_TD > _c is preferably in the range of 0.43 to 0.6,
More preferably, it is in the range of 0.46 to 0.58.

The amorphous orientation parameter [MD-AOP] of the MD of the polypropylene film of the present invention is not particularly limited. In consideration of improving the adhesion of the film to the container, it is preferably 0.15 or more, more preferably 0.16 to 0.22, and further more preferably 0.17 to 0.2. Is preferred.

The degree of orientation <cos ² φ _MD > _a of the amorphous part of MD of the film is not particularly limited,
0.2 or more, preferably 0.22 to 0.32
Is more preferably in the range of 0.25 to 0.25.
More preferably, it is in the range of 0.3.

The refractive indices n _MD , n _TD and n _ND of the films MD, TD and ND are not particularly limited,
n _MD is preferably in the range of 1.485 to 1.505, and more preferably in the range of 1.48 to 1.50. Further, n _TD is preferably in the range of 1.495 to 1.525, and more preferably in the range of 1.50 to 1.52. Also, n _ND is 1.485 to 1.50.
5, and more preferably 1.48 to 1.50.

[0031] The film MD, the degree of orientation of crystals of the ^{_{TD <cos 2 φ MD> c}} , <cos 2 φ TD> c is not particularly limited, the <cos ² φ _{MD> c} 0 It is preferably in the range of .15 to 0.35, and more preferably in the range of 0.2 to 0.3. <Cos ² φ _TD > _c is 0.55 to 0.5.
It is preferably in the range of 75, and more preferably in the range of 0.6 to 0.7.

The melting point of the polypropylene film of the present invention is not particularly limited, but is preferably 160 ° C. or lower, more preferably 120 ° C. to 155 ° C., further more preferably 130 ° C. to 150%. Is most preferred. Here, the melting point of the polypropylene film is the maximum peak temperature of the crystal melting curve when the temperature is measured by a differential scanning calorimeter (DSC).

Further, the plane orientation index of the film (hereinafter referred to as [P
OI]) is not particularly limited,
It is preferably in the range of 0.5 to 0.9, and 0.55
More preferably, it is in the range of 0.85 to 0.85.

The above-mentioned plane orientation index ([POI]) is an index showing the degree of plane orientation of the polypropylene crystal (010) plane to a plane parallel to the film plane, and can be determined by the following method. . Using a transmission method rotating sample device, X-rays are incident from the direction perpendicular to the film surface while rotating the polypropylene film at a high speed about an axis perpendicular to the film surface, and the diffraction intensity is measured. The diffraction intensity curve was subjected to peak separation into an amorphous peak and each of the crystalline peaks.
11) The plane orientation index ([POI]) is obtained from the ratio of the peak intensities of the surface reflection (2θ = about 21.4 °) and the (040) plane reflection (2θ = about 17.1 °) by the following equation (2). Can be

[POI] = log ｛1.508 × I ₍₁₁₁₎ / I ₍₀₄₀₎ ｝ (9) where I ₍₁₁₁₎ : peak intensity of (111) plane 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. Journal of Macro Molecular Science, Physics by Z. Mencik
molecularr Science, Physics), B6, 101 (1972), the intensity ratio I calculated from theoretical intensity I ₍₀₄₀₎ and I ₍₁₁₁₎ when polypropylene crystals are completely randomly oriented.
₍₀₄₀₎ / I ₍₁₁₁₎ = 116.9 / 77.5 = 1.508
(Reciprocal of the value of I _{(1 11)} / I ₍₀₄₀₎₎ . 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 [P0I] is 0, and the (010) plane is parallel to the film plane. The more the surface is oriented, the larger the value of [POI].

As a raw material of the polypropylene film of the present invention, known polypropylene 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.

The propylene-α-olefin copolymer has a content of a monomer unit based on one or more α-olefins other than propylene of 20 mol% or less, and more preferably 15 mol% or less. It is preferably an α-olefin copolymer or a mixture of these polymers. Examples of the α-olefin include ethylene, 1-
Butene, 1-pentene, 1-hexene, 1-heptene,
1-octene, 1-nonene, 1-decene, 4-methyl-
1-pentene 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.

Further, the polypropylene is a propylene homopolymer, and, when the content of a propylene -α- olefin copolymer other than propylene α- olefin is less than 1 mol%, indicating the crystalline ¹³ C-NMR
The isotactic pentad fraction is not particularly limited, but is preferably 0.6 to 0.97, more preferably 0.65 to 0.94,
More preferably, it is 0.7 to 0.9. The isotactic pentad fraction as referred to herein means A.P. ¹³ C-, published by Macromolecules, ¹³ , 267 (1980) by A. Zambelli et al.
It is a fraction in which five propylene units determined based on the assignment of peaks in the NMR spectrum continuously have the same configuration.

The melt flow rate of the above polypropylene is not particularly limited, but is usually preferably in the range of 0.1 to 30 g / 10 min, and preferably 1 to 20 g / min in consideration of moldability into a film. The range is more preferably 10 minutes, and most preferably 3 to 15 g / 10 minutes.

The above polypropylene has a 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 view of the ease of forming the film and the fact that the melt tension is increased and the workability is improved, the number is preferably 2 to 20, and more preferably 4 to 10. The molecular weight distribution is determined by gel permeation chromatography using o-dichlorobenzene as a solvent (hereinafter referred to as G
PC), and the calibration curve is calibrated with standard polystyrene.

The melting point of the above polypropylene is not particularly limited, but is preferably 165 ° C. or lower, more preferably 120 to 155 ° C., and further preferably 125 to 150 ° C. Is preferred. Here, the melting point of polypropylene is the maximum peak temperature of the crystal melting curve at the time of temperature rise measured by a differential scanning calorimeter (DSC).

In the present invention, the raw material of the polypropylene film is the same as the amorphous orientation parameter [T
D-AOP] may be appropriately selected from the above-mentioned raw materials so as to fall within the range specified in the present invention.
In view of easily achieving the range defined in the present invention described above, it is more preferable to satisfy the following requirements.

That is, the amount of components eluted at 70 ° C. or less by the temperature rising elution fractionation method (hereinafter also referred to as TREF) of the raw material of the polypropylene film is considered in consideration of obtaining more excellent heat shrinkage characteristics when formed into a film. , 5-5
It is preferably 0% by weight, more preferably 10 to 40% by weight, and further preferably 15 to 35% by weight. If the amount of the eluted component at 70 ° C. or lower by TREF is more than 50% by weight, the rigidity and blocking resistance of the film are undesirably reduced.

The TR of the raw material of the polypropylene film
The amount of eluted components at 20 ° C. or lower by EF is not particularly limited, but is 25% by weight in consideration of the film surface properties such as blocking resistance, scratch resistance, and slipperiness of the formed polypropylene film. It is preferably not more than 2% by weight, more preferably 2 to 20% by weight, and further preferably 5 to 15% by weight.

In the above TREF, various polyolefin resins are dissolved in a solvent at different temperatures, and the elution amount (concentration) of the polyolefin resin at each dissolution temperature is measured to evaluate the crystallinity distribution of the polyolefin resin. Is the way. For details, use a column filled with an inert carrier such as diatomaceous earth and silica beads, and inject into the column a sample solution of any concentration obtained by dissolving the sample polyolefin resin in a solvent consisting of ortho-dichlorobenzene. After lowering the temperature of the column and attaching the sample to the surface of the packing material, the temperature of the column was increased while passing a solvent consisting of orthodichlorobenzene through the column, and elution was performed at each temperature. Detecting the concentration of the coming polyolefin resin,
This is a method of measuring the crystallinity distribution of the polyolefin resin from the value of the elution amount (% by weight) of the polyolefin resin and the temperature (° C.) in the column at that time. Since the dissolution temperature increases as the dissolution component becomes more easily crystallized, the distribution of the crystallinity of the polyolefin resin can be known by determining the relationship between the dissolution temperature and the dissolution amount (% by weight) of the polyolefin resin.

In the above method, the rate of decrease in the temperature of the column is the rate required for crystallization of the crystalline portion contained in the polyolefin resin of the sample at a predetermined temperature, and the rate of increase in the temperature of the column is the rate at each temperature. It is necessary to adjust the rate at which the dissolution of the sample can be completed, and the rate at which the temperature of the column falls and the rate at which the temperature of the column rises may be determined in advance by experiments. The rate of temperature drop of the column is 2 ° C /
Minutes or less, and the temperature rise rate of the column is 4
It is determined in the range of ° C / min or less.

Here, the amount of the eluting component at 70 ° C. or lower by TREF is determined by the elution curve showing the relationship between the elution temperature (° C.) obtained by TREF measurement and the integrated elution amount (% by weight) at an elution temperature of 70 ° C. And the amount of the components soluble in the solvent at 70 ° C. or lower.

Similarly, the amount of components eluted at 20 ° C. or lower by TREF is the integrated elution amount (% by weight) at an elution temperature of 20 ° C. in the above elution curve, and the amount of components soluble in a solvent at 20 ° C. or lower. It is.

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.
Nonene, 1-decene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-
Olefin homopolymers such as methyl-1-pentene, vinylcyclobutane, vinylcyclopentane, and vinylcyclohexane, copolymers of these olefins, or polyolefin resins such as a mixture of two or more of these polymers, Examples thereof include thermoplastic resins such as aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, rosin derivatives, terpene resins, terpene phenol resins, and petroleum resins such as hydrogenated resins.

The raw materials of the polypropylene film may further contain, 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 crystal nucleating agent. , Surfactants, pigments, fillers,
Even if various known additives such as a foaming agent, a foaming aid, a plasticizer, a cross-linking agent, a cross-linking aid, a flame retardant, a dispersant, a processing aid, and a filler are compounded within a range not to impair the effects of the present invention. Good.

Although the thickness of the polypropylene film of the present invention is not particularly limited, it is usually preferably 3 to 300 μm, and preferably 10 to 300 μm, in consideration of film rigidity and film forming property.
To 250 μm, more preferably 15 to 250 μm.
It is preferably in the range of 150 μm.

As the method for producing the polypropylene film of the present invention, known methods are employed without any particular limitation, but the physical properties specified in the present invention can be achieved by the following methods.

That is, as a stretching method, a tubular sheet is uniaxially or biaxially stretched by an inflation method, and a sheet is formed by a T-die method.
A sequential biaxial stretching method in which the film is sequentially stretched in a film flow direction (MD) and a direction (TD) orthogonal to the film flow direction;
After forming the sheet by a die method, a simultaneous biaxial stretching method in which the sheet is stretched simultaneously in the longitudinal and transverse directions, and the like. Examples of the method for setting the [TD-AOP] of the polypropylene film in the range specified in the present invention include: Particularly, the above-mentioned T-die-sequential biaxial stretching method is preferable.

As an example of the method for producing a polypropylene film by the above-mentioned T-die-sequential biaxial stretching method, first, the above-mentioned polypropylene film raw material is formed into a sheet or film (hereinafter abbreviated as an unstretched sheet) by a T-die extruder. Molding. Next, the unstretched sheet is supplied to an MD stretching apparatus, and heated at a roll temperature of 60 to 155 ° C., preferably 70 to 140 ° C., 2 to 7 times, preferably 3 to 6 times.
And then the temperature in the tenter is set to 10 using a tenter.
0 to 180 ° C, preferably 5 to 13 at 110 to 170 ° C
Times, preferably stretched to TD at 7 to 12 times, and in the above stretching, the area stretch ratio which is the product of MD stretch ratio and TD stretch ratio is 10 to 90 times, preferably 20 to 70 times,
Furthermore, the ratio of TD stretching ratio to MD stretching ratio (TD / MD
Stretching conditions may be adjusted so that the draw ratio is in the range of 0.8 to 4, preferably 1 to 3.

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 crystallinity of the formed unstretched sheet is 6
It is preferable to appropriately adjust the cooling temperature and the various physical properties of the above-mentioned raw materials so as to be 0% or less, preferably 30 to 50%. The crystallinity of the unstretched sheet is
Known methods can be used for forming the unstretched sheet having the crystallinity in the above range measured by the above-described method using DSC, without particular limitation. Usually, a molten resin extruded into a sheet is used. A method of contacting with one or several cooling rolls to cool and solidify is provided. The thickness of the unstretched sheet is appropriately adjusted in consideration 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 formed, the forming speed, and the like.
Is more preferable, and it is more preferable that it is the range of 20-60 degreeC. Further, in forming the unstretched sheet, a method in which a cooling means such as an air knife, an air chamber, and a water-cooled pan is used in combination with a cooling roll is more preferable in order to enhance a cooling effect and easily control the crystallinity.

Since the crystallinity of the unstretched sheet changes depending on the thickness of the sheet, the cooling temperature, and the molding speed, it is preferable to appropriately adjust these conditions. 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 increases, so that the crystallinity of the unstretched sheet tends to increase. Therefore, in this case, the crystallinity of the unstretched sheet can be adjusted to the above range by a method of lowering the cooling temperature or a method of lowering the molding speed. However, if the cooling temperature is too low, the surface of the unstretched sheet may be roughened or deformed, and the crystallinity may be increased. Therefore, it is preferable to appropriately adjust the sheet in accordance with the sheet thickness, the forming speed, and the like.

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 0.2 to 0.8, more preferably 0.1 to 0.8. M is selected to be in the range of 3 to 0.75, and even more preferably in the range of 0.35 to 0.7.
It is preferable to appropriately adjust the D stretching ratio, the stretching temperature, and the various physical properties of the above raw materials in order to obtain the polypropylene film having the 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, an unstretched sheet before MD stretching is treated at a temperature lower by 60 ° C. than the melting point of the polypropylene raw material.
Heat to a temperature 10 ° C. lower than the melting point of the polypropylene raw material, preferably 50 ° C. lower than the melting point of the polypropylene raw material to 20 ° C. lower than the melting point of the polypropylene raw material, 2 to 7 times, preferably 3 to 6 times MD. A stretching method is suitably employed.

The c-axis orientation coefficient is a value quantitatively representing the degree of uniaxial orientation of the c-axis (molecular chain axis) of the polypropylene crystal to the MD of the MD-stretched sheet, and is determined by an X-ray diffraction method. be able to. Specifically, an X-ray diffractometer equipped with a fiber sample measuring device is used to input X-rays perpendicularly to the sheet surface of the MD-stretched sheet, and to move the MD-stretched sheet along an axis perpendicular to the sheet surface (X-ray incidence direction). By rotating slowly around an axis (parallel to), the azimuthal intensity distribution curve of the (110) plane and the (040) plane of the polypropylene crystal is obtained. Zet mentioned above. Wu. ZWWilchinsky [Journal of Applied Physcis, 3
1,1969 (1960)], and (110)
From the orientation distribution curve (crystal plane density distribution curve) of the (040) plane and the (040) plane, the normal of each crystal plane and the MD of the MD stretched sheet
And the root mean square of the direction cosine of
The root mean square <cos ² φ _MD > _c of the direction cosine between the axis and the MD is obtained. The c-axis orientation coefficient of the MD stretched sheet is as follows (1)
0) can be calculated by the following equation.

[C-axis orientation coefficient] = (3 <cos ² φc _{, Z} > −1) / 2 (10) Next, the TD stretching method of the MD stretched sheet obtained by the above-mentioned method is, for example, before TD stretching. The MD stretched sheet of the above, a temperature 60 ° C. lower than the melting point of the polypropylene raw material to a temperature 60 ° C. higher than the melting point of the polypropylene raw material, preferably a temperature 40 ° C. lower than the melting point of the polypropylene raw material to 40 ° C. higher than the melting point of the polypropylene raw material Heat to temperature, 5
A TD stretching method of 13 times, preferably 7 to 12 times is suitably employed.

In the production of a general biaxially stretched film, a heat treatment operation is performed while allowing the relaxation of 0 to 15% in order to relax the tension of the film after TD stretching. Taking into account that the heat shrinkage rate of the heat treatment is further increased, the relaxation rate is preferably 10% or less, preferably 5% or less, and more preferably, the heat treatment operation is not performed.

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, a flame treatment and a plasma treatment, if necessary.

The polypropylene film of the present invention may be a single-layer film or a laminated film obtained by laminating two or more resins having different properties, as long as it has the physical properties defined in the present invention. Good. Further, a heat seal layer may be laminated on one or both surfaces of the polypropylene film for the purpose of imparting a function such as heat sealability to the polypropylene film of the present invention as long as the effects of the present invention are not impaired.

[0065]

As will be understood from the above description, according to the present invention, when a package having a large heat shrinkage is subjected to heat shrink wrapping such as a food container, the film adheres well to the container. It is possible to obtain a polypropylene film which is free from wrinkles and uneven shrinkage, has a high tensile modulus and is suitable for automatic packaging.

In the present invention, it is not yet clear why the polypropylene film having an amorphous orientation parameter [TD-AOP] of TD in a specific range is excellent in heat shrinkage characteristics when heat shrink wrapped. The present inventors think as follows based on the following analysis results.

In a stretched crystalline polypropylene film, the heat shrinkage increases as the crystallinity of the film decreases and as the orientation of the film increases. In addition, it was found that the structure of the polypropylene film after shrinking by heating had higher crystallinity and lower orientation than before heating. From this, the change in the higher-order structure due to the heat shrinkage of the polypropylene film is caused by the tight tie connecting the crystals, which exists in the amorphous part of the long-period structure in which the crystal part and the amorphous part are alternately continuous. When the molecule is under high temperature,
It is presumed that the size of the film shrinks as a result of being taken into the crystal due to an increase in the crystal part (recrystallization), or being relaxed due to thermal motion. Therefore, by increasing the number of tie molecules in the amorphous portion of the film or by increasing the tension, the heat shrinkage of the film can be increased, and the tensile modulus can be increased. That is, increase the amorphous fraction of the film,
It is considered that by controlling the amorphous orientation state of the TD, the heat shrinkage property and the suitability for automatic packaging are improved.

As is clear from the above description, the polypropylene film of the present invention has excellent heat shrinkage properties and exhibits excellent physical properties which cannot be realized by the conventional biaxially oriented polypropylene film. Therefore, the polypropylene film of the present invention can be suitably used not only as a general packaging film but also as a heat-shrinkable packaging film used particularly for heat-shrinkable packaging such as “band-wrapping packaging” for food containers and the like.

[0069]

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. The films and raw materials obtained in the following Examples and Comparative Examples were evaluated by the following methods.

(1) TD and MD amorphous orientation parameters of polypropylene film TD and MD amorphous orientation parameters [TD-AOP]
And [MD-AOP] are TD, MD,
ND refractive index n _TD , n _MD , n _ND , crystal c-axis and film M
Root mean square of direction cosines with D and TD, <cos ² φ _TD > _c , <cos ²
φ _MD > _c crystal fraction χ _c was determined and calculated by the above equation.

(1-1) Refractive index n _TD , n _MD , n _ND Automatic birefringence meter KOBRA-21AD manufactured by Oji Scientific Instruments
H was measured under the following conditions.

Measurement method: parallel Nicol rotation method Measurement wavelength: 590 nm The refractive indices n _TD , n _MD , and n _ND of the film are 0 ° and 4 °, respectively.
Calculated from the 0 ° retardation using the software attached to the instrument. An average refractive index value of 1.5 was input.

(1-2) The root mean square <cos ² φ _{110, TD} > _c , <cos ² _{φ040, TD} > _c of the direction cosine of the film MD and TD of the normal to the (110) and (040) planes , <Cos ² φ
_{110, MD} > _c , <cos ² φ _{040, MD} > _c Attach the JEOL X-ray diffractometer JDX-3500 to the JEOL Pole figure sample device DX-GOP4 and measure under the following conditions did.

Target: copper (Cu-Kα ray) Tube voltage-tube current: 30 kV-300 mA Monochrome: Graphite monochromator Detector: Scintillation counter Count time: 2.0 seconds a) Transmission method measurement Measurement method: DAH method α Measurement angle range: 0 to 30 ° α step angle: 5 ° β step angle: 5 ° Diverging slit: 0.2 Light receiving slit: 2.0 b) Reflection method Measurement method: Schulz method α measurement angle range: 30 to 90 ° α step angle: 5 ° Diverging slit: 0.5 Light receiving slit: 2.0 In this case, the film was cut out into a circular shape of 27 mmφ, and this was overlapped to a thickness of about 3 mm and used for measurement. 2θ
The angle is the (110) reflection (2θ) of the polypropylene α-type crystal.
= 13.8 °) and (040) reflection (2θ = 16.8)
°) was measured. The value of each direction cosine was calculated by the software attached to the equipment. In addition, a fine crystal powder obtained by crystallizing a polypropylene raw material from a tetralin dilute solution (1%) was used as a standard sample (random orientation sample).
The effect of X-ray absorption by the sample was calibrated (background corrected).

(1-3) Crystal fraction χ _c Using a DSC 6200 DSC device manufactured by Seiko Instruments Inc.
The polypropylene film was filled in an aluminum pan, and the heat of fusion was measured under the following conditions.

Sample amount: about 5 mg Atmospheric gas: nitrogen (flow rate: 20 ml / min) Temperature condition: 230 ° C. at a rate of 10 ° C./min from room temperature
The heat of fusion was calculated from the area of the endothermic peak in the melting curve.

The heat of fusion of the unstretched sheet was measured in the same manner.

(2) Melting Point of Polypropylene Film Using a DSC 6200 DSC manufactured by Seiko Denshi,
The polypropylene film was filled in an aluminum pan, and the heat of fusion was measured under the following conditions.

Sample amount: about 5 mg Atmospheric gas: nitrogen (flow rate: 20 ml / min) Temperature condition: 230 ° C. at a rate of 10 ° C./min from room temperature
The endothermic peak temperature of the melting curve was taken as the melting point.

(3) Plane orientation index [POI] of polypropylene film 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.

(4) c-axis orientation coefficient fc of MD-stretched sheet A fiber sample device was attached to an X-ray diffractometer JDX-3500 manufactured by JEOL Ltd. and measured 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 MD stretched sheet is 15 mm × width 5 in the stretching direction.
The strip sample cut into mm was mounted on a fiber sample device, and first, X-rays were made to enter the sheet surface perpendicularly, and 2θ scanning was performed by the vertical transmission method to obtain polypropylene crystals (110) and (040). ) Surface Bragg angle (2θ °)
It was determined. Next, the X-ray detector was fixed at the Bragg angle of the (110) plane, and the sample was rotated in-plane (β rotation).
10) The azimuthal intensity distribution curve was measured for the plane.
Similarly, the azimuthal intensity distribution curve of the (040) plane was measured. The background intensities of the (110) plane and (040) plane reflection positions of the X-ray diffraction profile measured by 2θ scanning due to air scattering and the like were determined, and the respective background intensities were calculated as (11
The orientation distribution curves (crystal plane density distribution curves) of the (110) and (040) planes were obtained by subtracting them from the azimuthal intensity distribution curves of the (0) and (040) planes. From these orientation distribution curves, the direction cosine of the normal to each crystal plane was determined by the method described above, and the c-axis orientation coefficient was calculated.

(5) Polypropylene copolymerization α-olefin content, isotactic pentad fraction Using JNM-GSX-270 ( ^13C- nuclear resonance frequency 67.8 MHz) manufactured by JEOL Ltd., the following conditions were used. Was measured.

Measurement mode: ¹ H-complete decoupling Pulse width: 7.0 microseconds (C45 degrees) Pulse repetition time: 3 seconds Integration frequency: 10000 times Solvent: mixed solvent of ortho-dichlorobenzene / deuterated benzene (90 / Sample concentration: 120 mg / 2.5 ml Solvent Measurement temperature: 120 ° C. In this case, the isotactic pentad fraction is ¹³ C-
It was determined by measuring a splitting peak in a methyl group region of an NMR spectrum. Also, the assignment of the peak in the methyl group region is described in A. Zambelli et al., [Macromolecules, 13, 267 (1980)].
According to

(6) Melt flow rate (MFR) of polypropylene Measured according to JIS K7210.

(7) Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) of polypropylene 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: Showa Denko “SHODEX UT” 8
07, 806M, 806M, 802.5 are connected in series and used.

Sample concentration: 0.1% by weight Injection amount: 0.50 ml (8) Melting point of polypropylene Using a DSC 6200 manufactured by Seiko Denshi 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. in minutes and then raised to 230 ° C. at 10 ° C./minute. The endothermic peak temperature of the melting curve was taken as the melting point.

(9) Polypropylene by TREF
Amount of eluted components at 0 ° C. or lower and amounts of eluted components at 20 ° C. or lower Automatic TREF device SSC-730 manufactured by Senshu Kagaku
The measurement was performed under the following conditions using 0ATREF.

Solvent: ortho-dichlorobenzene Flow rate: 150 ml / hour Heating rate: 4 ° C./hour Detector: infrared detector Measurement wave number: 3.41 μm Column: “Packed Column 30” manufactured by Senshu Chemical
φ ”, 30 mmφ × 300 mm Concentration: 1 g / 120 ml Injection amount: 100 ml In this case, the sample solution is introduced into the column at 145 ° C., and then gradually cooled to 10 ° C. at a rate of 2 ° C./hour to fill the sample polymer. After the adsorption on the agent surface, the column temperature was raised under the above conditions, and the concentration of the polymer eluted at each temperature was measured with an infrared detector.

(10) Thermal Shrinkage of Polypropylene Film A sample was cut out into a tape shape having a length of 600 mm and a width of 15 mm with the TD and MD of the polypropylene film in the length direction. After marking, the film sample was left in an atmosphere at 120 ° C. for 15 minutes, taken out and cooled at room temperature for 15 minutes, the length between marks was measured, and the heat shrinkage was measured by the following formula (11).

Heat shrinkage (%) = {(L _O −L _S ) / L _O } × 100 (11) where L _O : length between marks before heat shrink (500 mm) L _S : after heat shrink In this example, a TD heat shrinkage of 15% or more was accepted.

(11) Tensile Modulus of Polypropylene Film According to JIS K7113, the tensile modulus of TD and MD was measured by the following method.

TD and M from polypropylene film
D, a film sample was cut into a strip having a width of 10 mm and a length of 100 mm, and both ends of the sample were fixed with a chuck of a tensile strength measuring machine (Autograph; manufactured by Shimadzu Corporation). In this case, adjustment was made so that the distance between the chucks in the longitudinal direction of the sample was 20 mm. A tensile test was performed at a tensile speed of 20 mm / min to obtain a tensile stress-strain curve. The tensile modulus was calculated by the following equation (12) using the straight line at the beginning of the tensile stress-strain curve.

Tensile modulus = Δδ / Δε (12) where Δδ: difference in stress between two points on a straight line due to the original average cross-sectional area of the sample Δε: difference in strain between the same two points By an automatic packaging machine Considering the packaging, in this embodiment, M
It is preferable that the D tensile modulus is in the range of 800 to 1500 MPa and the TD tensile modulus is in the range of 1500 to 3000 MPa.

(12) Evaluation of appearance after heat shrink wrapping The polypropylene film was 150 mm in MD and 4 mm in TD.
The container was cut out so as to have a size of 50 mm, and the container shown in FIG. 1 (made of polystyrene, having an outer shape of 210 mm × 160 mm × 50 m
m). At this time, the film was wound so that the MD became free and the TD turned around the container, and the film was fixed to the container using an adhesive tape at the bottom of the container. The container around which the film is wound is shrink-wrapped at a set temperature of 150 ° C. using a universal shrinker manufactured by Kyowa Electric Co., Ltd. did.

A: Very good without wrinkles or uneven shrinkage.

：: Slight wrinkles and shrinkage unevenness are generated at the corners of the container, but at a level where there is no problem.

△: A level where the end of the lid is slightly deformed but no problem occurs.

X: Wrinkles and shrinkage unevenness occurred on the whole, resulting in poor appearance.

Δ: Insufficient shrinkage of the film and poor adhesion to the container.

In this example, the appearance evaluation criteria
~ △ was passed.

(13) Automatic packaging suitability Automatic bag making is performed using a PP500 type fusing seal bag making machine manufactured by Kyoei Printing Machinery Co., Ltd., and the state of the film passing between the guide rolls of the automatic bag making machine is observed. Automatic packaging suitability was evaluated. Continuous operation of automatic bag making was performed at a film feed speed of 75 mm / sec (100 shots / min) for 1 hour, and the state of the film passing through the guide roll was visually observed and evaluated according to the following criteria. .

A: Very good without any slack or meandering of the film.

：: The film slightly loosened wrinkles,
No problem for continuous operation.

△: The film has loose wrinkles and meandering, but recovers to a favorable state by adjusting the tension of the film during operation, and has no problem in continuous operation.

X: The film is extremely loose and wrinkled, meandering, and continuous operation by adjustment during operation is impossible.

In the present embodiment, the appearance evaluation criteria
~ △ was passed.

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, 0.2 parts by weight of stearyl diethanolamide as an antistatic agent, and an average particle size of 1.
After adding 0.1 parts by weight of 5 μm spherical polymethyl methacrylate particles and mixing with a Henschel mixer for 5 minutes,
230 ° C. using an extrusion granulator with a screw diameter of 65 mmφ
And pelletized to obtain raw material pellets.

(Production of Biaxially Stretched Film) Using the obtained raw material pellets, a biaxially oriented film was produced by the following method. Raw material pellets, screw diameter 90mmφ
Was heated and melted at 240 ° C. using a T-die sheet extruder, extruded, and an unstretched sheet was formed with a cooling roll at 40 ° C. 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 4.2 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 is subjected to TD by a tenter transverse stretching machine.
The film was stretched by TD at a mechanical magnification of 10 times to form a biaxially stretched film having a thickness of 30 μm. In addition, the thickness of the biaxially stretched film was adjusted by the extrusion amount of the T-die sheet extruder (thickness of the unstretched sheet).

On one side of the biaxially stretched film, 3
After subjecting to a corona discharge treatment of 0 W min / m ² and winding, the obtained biaxially stretched film was aged at 35 ° C. for 1 day. After aging, the amorphous orientation parameters [MD-AOP], [TD-AOP], crystallinity, plane orientation index [POI], and film melting point of the obtained biaxially stretched film were measured. The results are shown in Table 2.

The biaxially stretched film was evaluated for heat shrinkage, tensile elasticity, appearance after heat shrink wrapping, and suitability for dynamic wrapping. The results are shown in Table 3.

Examples 2 to 6 The same procedures as in Example 1 were carried out except that the draw ratios shown in Table 2 were used. The results are shown in Tables 2 and 3.

Comparative Example 1 Example 1 was repeated except that polypropylene B shown in Table 1 was used.
Was performed in the same manner as described above. The results are shown in Tables 2 and 3.

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

Example 7 Example 1 was repeated except that polypropylene C shown in Table 1 was used.
Was performed in the same manner as described above. The results are shown in Tables 2 and 3.

Examples 8 and 9 The same procedures as in Example 1 were carried out except that the polypropylenes D (Example 7) and E (Example 8) shown in Table 1 were used. The results are shown in Tables 2 and 3.

Example 10 The same procedure as in Example 1 was carried out except that polypropylene F (propylene homopolymer having an isotactic pentad fraction of 0.81 as measured by ¹³ C-NMR) shown in Table 1 was used. Was. The results are shown in Tables 2 and 3.

Example 11 Example 1 was repeated except that polypropylene G shown in Table 1 was used.
Was performed in the same manner as described above. The results are shown in Tables 2 and 3.

Example 12 Example 1 was repeated except that the polypropylene H shown in Table 1 was used.
Was performed in the same manner as described above. The results are shown in Tables 2 and 3.

Examples 13 and 14 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 was as shown in Table 2. The results are shown in Tables 2 and 3.

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

Example 15 In the production of a biaxially stretched film, after TD stretching, the film was subjected to TD stretching by 3% with respect to the entire width of the stretched film.
Example 2 except that the operation of relaxing in the (width direction) was performed.
Was performed in the same manner as described above. The results are shown in Tables 2 and 3.

Comparative Example 4 In the production of a biaxially stretched film, after TD stretching, the film was TD stretched by 20% with respect to the entire width of the stretched film.
Example 2 except that the operation of relaxing in the (width direction) was performed.
Was performed in the same manner as described above. The results are shown in Tables 2 and 3.

[0128]

[Table 1]

[0129]

[Table 2]

[0130]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment in which a packaged object is banded using the polypropylene film of the present invention.

[Explanation of symbols] 1: Lid 2: Container 3: Polypropylene film

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 3E067 AA11 AB01 BB16A BB18A CA01 EC28 FB01 4F071 AA15X AA20 AA20X AA21X AA84 AA87 AA88 AA89 AF05 AF11 AF31 AF61 AH04 BB08 BC01 4J002 BB121 A03A02 BB141 A03A02A AA17Q AA19Q AA21Q CA01 CA04 DA01 DA22 DA24 DA36 DA39 DA41 DA43 JA58

Claims (4)

[Claims] 1. A polypropylene film having an amorphous orientation parameter of 0.3 or more in a direction perpendicular to the film flow direction. 2. The polypropylene film according to claim 1, which has a crystallinity of 50% or less. 3. The polypropylene film according to claim 1, wherein the content of the eluted component at 70 ° C. or lower by a temperature-rise elution fractionation method is 5 to 50% by weight. 4. A heat-shrinkable packaging film comprising the polypropylene film according to claim 1.