JP7257245B2 - the film - Google Patents

Description

The present invention relates to films. More specifically, the present invention relates to a film that shrinks in close contact with the object to be packaged by thermal shrinkage. In particular, the present invention relates to a heat-shrinkable film suitable for packaging objects to be reheated in a microwave oven after being packaged, such as lunch containers and containers for side dishes.

Shrink film for packaging can quickly and tightly wrap multiple products at the same time regardless of the shape and size of the items to be packaged, and the resulting packages have a beautiful appearance and display effect. It is often used for packaging food and miscellaneous goods because it enhances product value, keeps contents hygienic, and facilitates visual quality confirmation.

As a packaging method using such a packaging shrink film, it is common to give the film a little slack and then primarily package the contents, and then heat shrink the film with hot air or the like, and pillow shrink packaging is a typical method. For example. In general, this method involves covering an item to be packaged, such as food, stored in a container or tray with a film in a cylindrical shape, and then using a center sealing device such as a rotating roller type to seal the back surface of the item with a sealing line. The palms are heat-sealed so that they come together, and then both open ends of the tubular film are heat-sealed to form a bag, which is then heat-treated with hot air in a box called a shrink tunnel, and the inside is inserted through a previously provided needle hole. This is heated and shrunk while degassing the air. In addition to the above, the pillow shrink packaging includes a method of heating a bag-like film that is sealed on three sides and a sealed on four sides.

Typical examples of objects to be wrapped in pillow shrink packaging using such a film with needle holes include heat-resistant containers with lids made of polystyrene or filled polypropylene (PP) containing box lunches and side dishes. , Open polystyrene foam trays, PP trays, paper trays, etc., containing meat or fish. A method of shrinking by pressing is exemplified.

By the way, in the packaging of items to be packaged such as box lunches and side dishes, reheating in a microwave oven is often performed after packaging. Since the container is easily deformed by heat and pressure, juices and sauces contained in the ingredients in the container are likely to flow out of the container, and the outside of the container is easily soiled. Therefore, in order to moderately release the pressure during microwave heating, one or two places on the top surface of the container lid are punched out in a U-shape as a steam port.

On the other hand, if the needle hole attached during shrink-wrapping is too large, small insects such as flea flies can enter through the needle hole during the distribution of bento lunches and side dishes, and foreign matter can enter the product through the steam port. There is a risk of
An example of this is cut vegetable packaging in which vegetables such as radishes and Chinese cabbage are cut into 1/2 or 1/4 and then directly wrapped in film. Therefore, it is necessary to prevent the invasion of insects.

In addition, these lunch boxes, side dishes, cut vegetables, and the like are recently packaged and shipped collectively at a pack center. Due to the enormous amount of packages that need to be produced per day, increasing the speed of packaging has become very important.

As an approach to the problems described above, for example, Patent Document 1 discloses a film having through holes formed using a diamond roll.

Japanese Patent No. 3983365

If the through-hole exists in a portion that contacts the packaging machine during packaging, the hole becomes a notch and tears occur.
However, since the method of Patent Document 1 tends to cause variation in the size of the holes that can be formed, in order to sufficiently deaerate during packaging, holes with a high density or large size are required in the perforated part of the film. An open film must be used.
When a film with a high pore density is used, there are demerits such as poor appearance of the package and small insects being easily penetrated into the package due to connection of holes due to stimulus or impact during transportation.
Needless to say, when a film with large pore size is used, small insects are more likely to enter.

Therefore, there is currently a need for a film that not only prevents small insects from entering the package, but also has a hole density and size that allows packaging to look good without slowing down the packaging speed.

An object of the present invention is to provide a film capable of producing a good-looking package without slowing down the packaging speed and reliably preventing entry of small insects.

That is, the present invention is as follows.
[1]
A film having holes,
The outline of the hole is
a curved portion AC located on the outer side in the curvature radial direction;
a curved portion DF located inside in the curvature radial direction and having a center of curvature on the same side as the curved portion AC;
a line segment AD connecting one terminal point A of the curved portion AC and the terminal point D of the curved portion DF closest to the terminal point A;
a line segment CF connecting the other terminal point C of the curved portion AC and the terminal point F of the curved portion DF closest to the terminal point C;
It is an arch shape of ACFDA surrounded by
the area of the pores is 100 μm ² to 45000 μm ² ,
A film characterized by:
[2]
A film having holes,
The outline of the hole is
a curved portion AC located on the outer side in the curvature radial direction;
a curved portion DF located inside in the curvature radial direction and having a center of curvature on the same side as the curved portion AC;
A line segment AJ extending from the end point A in a direction substantially perpendicular to the curvature radius 1 passing through one end point A of the curved portion AC and away from the curved portion AC; one of the curved portions DF A line segment DI extending from the terminal point D in a direction substantially perpendicular to the curvature radius 2 passing through the terminal point D of and in a direction away from the curved portion DF; and a line segment connecting the point J and the point I a polygonal line AJID consisting of a line segment JI that is substantially parallel to a straight line connecting the terminal point A and the terminal point D;
a line segment CG extending from the terminal point C in a direction substantially perpendicular to the radius of curvature 3 passing through the other terminal point C of the curved portion AC and away from the curved portion AC;
A line segment FH extending from the end point F in a direction substantially perpendicular to the curvature radius 4 passing through the other end point F of the curved portion DF and away from the curved portion DF; and a point H and a point G a polygonal line CGHF consisting of a line segment GH which is a line segment connecting between and is substantially parallel to a straight line connecting the terminal point C and the terminal point D;
is an inverted U shape of ACGHFFDIJA surrounded by
the area of the pores is 100 μm ² to 45000 μm ² ,
A film characterized by:
[3]
The film according to [1] or [2], wherein the extending length of the curved portion located on the outer side in the curvature radius direction is 100 μm or more and 600 μm or less.
[4]
The film according to any one of [1] to [3], wherein the linear length between both ends of the curved portion positioned on the outer side in the curvature radius direction is 100 μm or more and 300 μm or less.
[5]
[1] to [4] , wherein the maximum distance between a straight line connecting both ends of the curved portion located on the outer side in the curvature radial direction and the curved portion located on the outer side in the curvature radial direction is 1 μm or more and 300 μm or less. A film according to any one of the preceding claims.
[6]
The film according to any one of [1] to [5], wherein the extending length of the curved portion positioned inside in the radius direction of curvature is 100 μm or more and 600 μm or less.
[7]
The film according to any one of [1] to [6] , wherein the linear length between both ends of the curved portion positioned inside in the radius direction of curvature is 100 μm or more and 300 μm or less.
[8]
[1] to [7] , wherein the maximum distance between a straight line connecting both ends of the curved portion located inside in the radius direction of curvature and the curved portion located inside in the radius direction of curvature is 1 μm or more and 300 μm or less. A film according to any one of the preceding claims.
[9]
The film according to any one of [1] to [8] , wherein the maximum distance between the curved portion located outside in the radial direction of curvature and the curved portion located inside in the radial direction of curvature is 1 μm or more and 300 μm or less .
[ 10]
The film according to any one of [1] to [9], wherein the pores are deformed into a substantially circular shape when the film is heated at 140° C. for 3 seconds.
[11]
The film according to any one of [1] to [10], wherein when the film is heated at 140° C. for 3 seconds, the pore enlargement ratio before and after the heating is 100 to 200%.
[12]
The film according to any one of [1] to [11], wherein the perforated portion has a density of 10 to 100 holes/cm ² .
[13]
A boxed lunch/prepared dish package, characterized in that the boxed lunch/prepared dish is wrapped with the film according to any one of [1] to [12].
[14]
A cut vegetable package, characterized in that cut vegetables are wrapped with the film according to any one of [1] to [12].
[15]
A roll body, characterized in that the film according to any one of [1] to [12] is wound around a paper tube.

INDUSTRIAL APPLICABILITY The present invention can provide a film capable of producing a good-looking package without lowering the packaging speed and reliably preventing entry of small insects.

FIG. 3 is a schematic top view of holes provided in the film according to the first embodiment. It is the schematic diagram which looked at the hole provided in the film which concerns on 2nd embodiment from the top. FIG. 11 is a schematic top view of holes provided in a film according to a third embodiment. It is the schematic diagram which looked at the hole provided in the film which concerns on other embodiment from the top. It is the schematic diagram which looked at the hole provided in the film which concerns on other embodiment from the top. It is the schematic diagram which looked at the hole provided in the film which concerns on other embodiment from the top. It is the schematic diagram which looked at the hole provided in the film which concerns on other embodiment from the top. (A) shows a top view, and (B) shows an enlarged view of (A). It is the schematic diagram which looked at the hole provided in the film which concerns on other embodiment from the top. (A) shows a top view, and (B) shows an enlarged view of (A).

BEST MODE FOR CARRYING OUT THE INVENTION The film of the present invention will now be described in detail based on preferred embodiments shown in the accompanying drawings.
It should be noted that the present invention is not limited to the following embodiments.

(the film)
The film of this embodiment is a film provided with holes, for example, by perforation.
In the film of the present embodiment, the contour lines of the holes are on the same side including the curved portion located on the outer side in the curvature radial direction (outer curved portion) and the curved portion located on the inner side in the curvature radial direction (inner curved portion). It is essential to include at least two curves with centers of curvature.
In addition, in this embodiment, a hole means a through-hole which penetrates a film.

<First embodiment>

FIG. 1 is a top view of the first embodiment of the film of the present invention. For convenience of explanation, the upper side of FIG. 1 (the same applies to FIGS. 2 and 3) is hereinafter referred to as "upper", and the lower side thereof is referred to as "lower".
The shape of the holes in the film of the first embodiment will be described later.

The film of the present embodiment includes polyolefin films such as polyethylene films and polypropylene films; laminated films such as polyolefin and nylon or ethylene-vinyl alcohol copolymer; Films and polypropylene films are preferred, and polyethylene films are more preferred.

Examples of the polyethylene-based resin constituting the polyethylene-based film include ethylene-α-olefin copolymers and high-pressure low-density polyethylene. The polyethylene film may be a multilayer film or a single layer film.

The ethylene-α-olefin copolymer is a copolymer of ethylene and at least one monomer selected from α-olefins having 3 to 18 carbon atoms.
Examples of the α-olefin having 3 to 18 carbon atoms include propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, octene-1, decene-1, dodecene-1 and the like. be done.
The polymerization catalyst used in producing the ethylene-α-olefin copolymer is not particularly limited, and examples thereof include multi-site catalysts and single-site catalysts.
The above ethylene-α-olefin copolymers may be used singly or in combination of two or more different densities and comonomer species.

The high-pressure process low-density polyethylene is a low-density polyethylene produced by a high-pressure process, and is a polyethylene-based resin having long-chain branches in which ethylene, which is a repeating unit, is randomly branched and bonded.
The density of the high-pressure low-density polyethylene is preferably 0.910-0.929 g/cm ³ , more preferably 0.915-0.929 g/cm ³ . In addition, "density" means the value measured according to JISK6922.
Generally known methods can be used for the production of high-pressure low-density polyethylene. In general, high-pressure low-density polyethylene is produced by polymerizing ethylene and α-olefin in an autoclave or tube reactor at a high temperature and pressure of 100 to 300°C and 100 to 350 MPa in the presence of a free radical generator such as peroxide. can do.

The film of the present embodiment may contain 5 to 50% by mass of high-pressure low-density polyethylene in order to improve stretchability and extrusion stability. The amount of high-pressure low-density polyethylene used is preferably 8 to 40% by mass, more preferably 10 to 30% by mass. By making the high-pressure low-density polyethylene content 50% by mass or less, the elongation at break during heat-shrink packaging is improved, and tear troubles can be easily reduced.

When the film of the present embodiment is multi-layered, the internal layer contains an ethylene-α-olefin copolymer and an ethylene-vinyl acetate copolymer from the viewpoint of imparting flexibility and stretching stability to the film. It is preferable to let It is preferred to contain the ethylene-vinyl acetate copolymer used in the inner layer. In the ethylene-vinyl acetate copolymer used for the inner layer, as the content of vinyl acetate increases, the melting point decreases and the pliability increases. The vinyl acetate content is preferably 1 to 30% by mass, more preferably 1 to 20% by mass, still more preferably 1 to 15% by mass in the ethylene-vinyl acetate copolymer.

The film of the present embodiment may contain a resin such as a polypropylene-based resin, a styrene-based resin, a polybutene-based resin, or an ethylene-based resin in a range of 0 to 30% by mass as long as the transparency of the film is not impaired. Also, these resins may be used as inner layers in a multi-layered structure.

The film of the present embodiment is preferably a film subjected to a cross-linking treatment from the viewpoint that it is imparted with heat resistance and that it can be stably stretched even with a thickness of about 5 to 15 μm.
A gel fraction is used as a measure of the degree of cross-linking. Here, the gel fraction is the ratio of the portion remaining undissolved after the film is immersed in boiling paraxylene for 12 hours, and is expressed by the following formula.
Gel fraction (% by mass) = (mass of film after immersion/mass of film before immersion) x 100
The gel fraction of the film of the present embodiment is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, from the viewpoint of film stretchability and heat resistance.

Examples of the cross-linking treatment method include irradiation with energy rays such as electron beams, ultraviolet rays, X-rays, α-rays, and γ-rays. A preferable irradiation dose range for the cross-linking treatment is 10 to 150 kGy, and more preferably 20 to 120 kGy from the viewpoint of heat-sealing property and stretching stability.

A stretched film is preferable as the film of the present embodiment. Specifically, an unstretched heat-shrinkable film is subjected to a cross-linking treatment, and at a temperature 10°C or more higher than the melting peak temperature of the resin constituting each layer, a sequential biaxial expansion of 6 times or more in the machine direction and/or width direction is performed. Stretching or simultaneous biaxial stretching is preferred. As the stretching method, the double bubble inflation method is particularly preferable, and this method is suitable for stretching a thin film of about 10 μm.

In this specification, the machine direction (MD direction) refers to the extrusion direction during film formation, and the width direction (TD direction) refers to the direction orthogonal to the extrusion direction on the film surface.

Specific examples of the manufacturing method for film formation by the double bubble inflation method include the following methods.
Using an extruder, the resin composition constituting each layer is melt-extruded, and the layers are joined one by one in an annular die, or joined at once in an annular die to obtain a multi-layer tubular unstretched material. . At this time, one extruder may be used for each layer, or the resin composition may be divided into two or more from one extruder until the resin composition flows into the annular die, and may be a plurality of layers. . This was quenched and solidified and guided into a stretching machine, and while setting the heating temperature at the stretching start point in the range from the melting point of the resin composition -10 ° C. to the melting point +40 ° C., air between nip rolls provided with a speed difference. Injection is performed, and stretching is performed by 4.0 times or more in each of the machine direction and the width direction.
The upper limit of the draw ratio is preferably 12.0 times or less from the viewpoint of drawing stability. By stretching at a temperature equal to or higher than the melting point of the resin composition that constitutes each layer, high-ratio stretching is possible, and a film with a high shrinkage ratio can be obtained.

The film of the present embodiment preferably has a shrinkage rate at 100° C. of 1% or more and less than 30%, and a shrinkage rate at 110° C. of 30% or more and 95% or less. In addition, from the viewpoint of good packaging finish, the shrinkage rate at 140° C. is preferably 68% or more and 95% or less.
Here, the shrinkage rate is the average value of the shrinkage rate in the machine direction and the shrinkage rate in the width direction of the film.
The shrinkage rate is obtained by measuring the lengths in the machine direction and width direction of the film before heating (before shrinking) and after heating for 30 minutes in a hot air dryer at each temperature (after shrinking), and using the measured lengths, It can be obtained by calculating the shrinkage rate in each direction from the following formula and calculating the average of the shrinkage rate in the machine direction and the shrinkage rate in the width direction.
Shrinkage rate (%) = {(length before shrinkage - length after shrinkage) / length before shrinkage} x 100

When the shrinkage ratio of the film of the present embodiment is within the above range, the container to be packaged is less likely to deform when the packaging container heat-shrink wrapped with the film is reheated by heating in a microwave oven or the like, and low-temperature packaging is easy. Become. The low-temperature packaging referred to here includes lowering the set temperature of the shrink tunnel during heat shrink packaging, shortening the passage time in the shrink tunnel, keeping the seal line away from the package, etc., and suppressing shrinkage fine wrinkles. can.

The obtained film can be slit into a predetermined size and used for packaging.

The thickness of the film of the present embodiment is preferably 5 to 15 μm, more preferably 6 to 12 μm, even more preferably 7 to 10 μm, from the viewpoint of resource saving and practicality of the film. A film having a thickness of 10 μm or less is sufficient as a film for packaging box lunches and side dishes in containers with lids.

The film of this embodiment may contain a surfactant or an antifogging agent in any of the constituent layers. For example, additives such as antifogging agents such as glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, ethylene oxide adducts, and plasticizers such as liquid paraffin are added to the resin composition constituting each layer at 0.00%. A content of 1 to 10.0% by mass is preferable because the processability and the running properties of the film during packaging are improved. In particular, from the viewpoint of transparency, it is more preferable to blend 0.5 to 10% by mass of polyglycerin fatty acid ester or the like with respect to the resin composition constituting each layer. It is more preferable to blend 0.8 to 6% by mass.
One of the above additives may be used alone, or two or more of them may be used in combination.

In the film of this embodiment, any of the constituent layers contains a lubricant such as natural silica, synthetic silica, saturated fatty acid amide, unsaturated fatty acid amide, talc, etc. within a range that does not impair the original characteristics and transparency. may

The film of the present embodiment may be subjected to surface treatments such as corona treatment, ozone treatment, and flame treatment from the viewpoint of making the film suitable for printing applications. The above surface treatment may be performed before or after perforation.
When printing is performed, 0.5 to 5.0% by mass of glycerin fatty acid ester or the like is added to the resin composition constituting the surface layer to be printed, and after forming a film, the surface to be printed is subjected to corona treatment. It is preferable to perform the printing process after performing the printing process. From the viewpoint of antistatic properties and prevention of ink peeling, the amount of glycerin fatty acid ester added is more preferably 0.8 to 3.0% by mass relative to the resin composition constituting the surface layer.

Furthermore, the film of the present embodiment may contain tackifying resins such as Alcon (trademark), Clearon (trademark), and Imarve (trademark), and petroleum-based resins as plasticizers in any of the layers constituting the film. . When the content of the plasticizer is 0.1 to 10% by mass with respect to the resin composition constituting each layer, shrinkage and transparency may be improved.

Hereinafter, the shape of the holes in the film of the first embodiment of this embodiment will be described in detail.

As shown in FIG. 1, the shape of the holes of the film of the first embodiment in a plan view is an arch shape.
The outline of the hole has an upwardly convex curved line portion ABC and an upwardly convex curved line portion DEF. Point B is the midpoint of the curved portion from A to C, and point E is the midpoint of the curved portion from D to F. The contour line of the hole has a straight portion AD and a straight portion CF in addition to the above contour portions.
The aperture is arcuate, bounded by the outline ABCFEDA.

In the example shown in FIG. 1, curved portion ABC and curved portion DEF are both part of a circular arc. However, the film of the present invention is not limited to such a configuration, and the shapes of the curved portion ABC and the curved portion DEF are not particularly limited. It may be a part, a part of a hyperbola, or the like.
In the present embodiment, the curved portion does not need to be a portion of a circular arc, a portion of an elliptical arc, a portion of a parabola, or a portion of a hyperbola in the strict sense, and is to the extent that it does not affect the planar view shape ( For example, the length (width) in the direction perpendicular to the direction of the curve (approximately 50 μm or less, preferably approximately 30 μm or less) may have a zigzag shape, a wavy shape, or the like.

In addition, in the film of the first embodiment, the direction of the holes is not particularly limited, but from the viewpoint of making it difficult to tear during packaging, as in the example shown in FIG. is preferably parallel to the TD direction. However, the film of the present invention is not limited to such a configuration.
In the present embodiment, the linear portion does not need to be a straight line in the strict sense, and the length (width) in the direction orthogonal to the direction of the straight line is 50 μm or less so as not to affect the shape in plan view. (preferably about 30 μm or less), it may have a zigzag shape, a wavy shape, or the like.

In the film of the first embodiment, from the viewpoint of processing stability, as in the example shown in FIG. 1, the length of the curved portion ABC located outside in the radial direction of curvature is located inside in the radial direction It is longer than the length of the curved portion DE. However, the film of the present invention is not limited to such a configuration.

In the first embodiment, when a large number of holes are provided as in the example shown in FIG. 1, all the holes may have the same shape in plan view, or some of the holes may have different shapes. may

In the first embodiment, the curved portion forming the outline of the hole extends with a shape such as a linear shape, a zigzag shape, or a wavy shape.

In the film of the first embodiment, the extended length LOe of the outer curved portion ABC is preferably 100 μm to 600 μm, more preferably 120 to 500 μm, and still more preferably 150 to 150 μm. 400 μm. When the thickness is 100 μm or more, the degassing speed of the air becomes sufficient when the film is heat shrunk, which is preferable. When the thickness is 600 μm or less, the pores after the film is heat-shrunk are sufficiently small, and insects can be prevented from entering, which is preferable.

In addition, the linear length LOs between both ends of the outer curved portion ABC, that is, the length of the line segment AC is preferably 100 μm to 300 μm, more preferably 100 to 250 μm. and more preferably 120 to 220 μm. When the thickness is 100 μm or more, the degassing speed of the air becomes sufficient when the film is heat shrunk, which is preferable. If the thickness is 300 μm or less, the pores after heat shrinkage of the film will be sufficiently small, and insects can be prevented from entering, which is preferable.

The maximum distance DO between the line segment AC connecting both ends of the curved portion ABC located outside and the curved portion located outside, that is, the distance between B and the line segment AC is 1 μm. It is preferably up to 300 μm, more preferably 5 to 250 μm, still more preferably 20 to 200 μm. When the thickness is 1 μm or more, the degassing rate of air becomes sufficient when the film is thermally shrunk, which is preferable. If the thickness is 300 μm or less, the pores after heat shrinkage of the film will be sufficiently small, and insects can be prevented from entering, which is preferable.

In the film of the first embodiment, the extension length LIe of the inner curved portion DE is preferably 100 μm to 600 μm, more preferably 120 to 500 μm, and even more preferably 150 to 150 μm. 400 μm. When the film has a thickness of 100 μm or more, when the film is heat shrunk, it is difficult for the pores to expand due to an excessive amount of heat, and the pores have an appropriate size to prevent insects from entering, which is preferable. When the thickness is 600 μm or less, the pores after the film is heat-shrunk are sufficiently small, and insects can be prevented from entering, which is preferable.

The linear length LIs between both ends of the inner curved portion DEF, that is, the length of the line segment DF is preferably 100 μm to 300 μm, more preferably 100 to 250 μm. , more preferably 120 to 220 μm. When the film has a thickness of 100 μm or more, when the film is heat shrunk, it is difficult for the pores to expand due to an excessive amount of heat, and the pores have an appropriate size to prevent insects from entering, which is preferable. If the thickness is 300 μm or less, the pores after heat shrinkage of the film will be sufficiently small, and insects can be prevented from entering, which is preferable.

The maximum distance DI between the line segment DF connecting both ends of the curved portion DEF located inside and the curved portion located inside, that is, the distance between E and the line segment DF is 1 μm. It is preferably up to 300 μm, more preferably 5 to 250 μm, still more preferably 20 to 200 μm. When the film has a thickness of 1 μm or more, when the film is heat shrunk, it is difficult for the pores to expand due to an excessive amount of heat, and the pores have an appropriate size to prevent insects from entering, which is preferable. If the thickness is 300 μm or less, the pores after heat shrinkage of the film will be sufficiently small, and insects can be prevented from entering, which is preferable.

In the film of the first embodiment, the maximum distance DOI between the outer curved portion ABC and the inner curved portion DEF, and the line segment BE in the example shown in FIG. The length is preferably 1 μm to 300 μm, more preferably 1 to 200 μm, even more preferably 1 to 100 μm. When the film is 1 μm or more, the pore diameter after heat shrinkage of the film is sufficient to allow air to escape without deformation of the container during heating in a microwave oven, which is preferable. If the thickness is 300 μm or less, the pores after heat shrinkage of the film will be sufficiently small, and insects can be prevented from entering, which is preferable.

In the first embodiment, LOe/LIe is preferably 0.17 to 6, more preferably 0.33 to 3, in order to enhance the effects of the present invention.

In the first embodiment, DOI/DO is preferably 0.01 to 100, more preferably 0.1 to 10, in order to enhance the effects of the present invention.

In the film of the first embodiment, the pore area S is preferably 100-45000 μm ² , more preferably 150-30000 μm ² , still more preferably 200-10000 μm ² .
Here, the area of the hole refers to the area of the region defined by the outline of the hole in plan view. Area of holes When a large number of holes are provided, the average of a large number of holes (for example, 10 arbitrary holes) may be used.

In the first embodiment, when a large number of holes are provided as in the example shown in FIG. Maximum distance DO between the straight line connecting both ends of the outer curved portion and the outer curved portion, extension length LIe of the inner curved portion, straight length LIs between both ends of the inner curved portion, and between both ends of the inner curved portion The maximum distance DI between the straight line connecting , the maximum distance DOI between the outer curved portion and the inner curved portion, and the area of the hole may all be averaged over a large number of holes.

In this embodiment, the object may be wrapped by wrapping the object with the film of the present embodiment and shrinking the film by heating.

The film of the present embodiment has a structure in which the portion of the curved portion DEF located inside is loose. Since the formed film portion has a structure in which it is bent to the front side and the back side in the film thickness direction, the rate of deformation of the holes increases during heat shrinkage. Therefore, the air inside the package can be quickly released during packaging, and a good-looking package can be produced without lowering the packaging speed. In addition, by providing the outer curved portion and the inner curved portion, the film is processed in a curved shape instead of a straight shape, so it is less likely to be affected by the notch effect during heat shrinkage, and cracks do not propagate. This makes it difficult to form holes of suitable size in the film.

The film of the present embodiment is heat-shrinkable, and when heated at 140° C. for 3 minutes, the holes are preferably deformed into a substantially circular shape.
Here, "substantially circular" is a concept including not only circular but also elliptical, oval, and polygonal (e.g., octagonal or larger).

The film of the present embodiment preferably has a pore diameter of 100 to 300 μm, more preferably 100 to 250 μm, and still more preferably 120 to 220 μm in a state in which the film is not heat-treated.
From the viewpoint of insect repellency, the film of the present embodiment preferably has a pore size of 100 to 400 μm, more preferably 150 to 350 μm, more preferably 150 to 150 μm after being heated at 140° C. for 3 seconds. More preferably, it is 300 μm.
The hole diameter is defined as the maximum diameter of the hole, and is defined as the maximum linear distance between any two points on the outline of the hole in plan view.

In the first embodiment, when a large number of holes are provided as in the example shown in FIG. 1, the hole diameters of the holes before and after the heat treatment may be an average of a large number of holes (for example, arbitrary 10 holes).

The film of the present embodiment preferably has a pore enlargement ratio of 100 to 200%, more preferably 120 to 180% before and after heating at 140° C. for 3 seconds.

Among them, when using a film with a heat shrinkage rate of 68% or more and 95% or less at 140 ° C., heat treatment at 140 ° C. for 3 seconds expands the hole diameter of the perforations by 100 to 200%, up to the range of 100 to 400 μm. Easier to expand.

The pore density of the film of the present embodiment is preferably 10 to 100/cm ² , more preferably 10, in the processed portion where the film is perforated without being subjected to heat treatment. 90/cm ² , more preferably 10 to 80/cm ² .
If the number of holes is 10/cm ² or more, air can be easily released during packaging, so packaging can be performed with a good appearance even at a high line speed. If the number of holes exceeds 100/cm ² , the holes will be conspicuous after packaging, resulting in poor appearance.
Here, the perforated portion refers to a set of regions in which at least one hole is provided in a range of 1 cm in the MD direction×1 cm in the TD direction.

In this embodiment, the minimum spacing of the holes is preferably 1-10 mm, more preferably 1-5 mm.
The minimum distance between holes means the minimum distance between any two holes on the film.

In this embodiment, the holes may be provided at a constant pitch in the MD direction and the TD width direction of the film. Note that the pitch may be different in the longitudinal direction and the width direction. Such a pitch is preferably 1-10 mm, more preferably 1-5 mm.

In this embodiment, the area of the perforated portion is preferably 3 to 40%, more preferably 5 to 30%, of the film area.

In this embodiment, when the film is used to package a container, which is an object to be packaged, the perforation is preferably performed in the central portion of the film so that the perforated area is located on the upper surface of the container. By locating the holes on the upper surface of the container, the steam that escapes from the steam port of the container lid when the container is overheated in the microwave oven can be easily released, and deformation of the container can be suppressed.

In addition, it is desirable that the perforated portion be located inside the width of the top surface of the container in the TD direction so as not to cause breakage due to contact with the container or packaging machine during packaging.

The perforated processed portion may be formed continuously in the TD direction of the film, and the width of the processed portion in the TD direction may be adjusted to 2 to 50% of the circumference of the object to be packaged.
In addition, the peripheral length of the object to be packaged means the peripheral length of the object to be packaged wrapped with the film of the present embodiment in the film TD direction.

The perforation processing method of the present film is not particularly limited as long as perforations satisfying the present invention can be formed. The perforations of this embodiment are formed by a well-known device as described in JP-B-10-2805343, JP-A-2016-059967, and the like. That is, the holes of the present embodiment are formed by passing the film between a bladed roller having a large number of minute protruded blades formed on the peripheral surface and a receiving roller that rotates together.
At that time, the hole of the present embodiment can be formed by devising the shape of the projecting blade. Also, two or more films may be stacked and perforated.

<Second embodiment>
FIG. 2 is a top view of the second embodiment of the film of the present invention.
Hereinafter, the second embodiment of the film of the present invention will be described with reference to this figure, but the description will focus on the differences from the above-described first embodiment, and the description of the same items will be omitted.

As shown in FIG. 2, the shape of the holes of the film of the second embodiment in a plan view is a crescent shape.
The outline of the hole has an upwardly convex curved line portion ABC and an upwardly convex curved line portion DEF. Point B is the midpoint of the curved portion from A to C, and point E is the midpoint of the curved portion from D to F.
The pore is crescent-shaped, bounded by the ABCEA outline.

In the example shown in FIG. 2, curve segment ABC and curve segment AEC are both part of an elliptical arc. However, the film of the present invention is not limited to such a configuration, and the curved portion ABC and the curved portion AEC are not particularly limited. , a portion of a hyperbola, or the like.

<Third Embodiment>
FIG. 3 is a top view of the third embodiment of the film of the present invention.
Hereinafter, the third embodiment of the film of the present invention will be described with reference to this figure, but the description will focus on the differences from the above-described first and second embodiments, and similar items will not be described. omitted.
As shown in FIG. 3, the hole of the film of the third embodiment has an inverted U shape in plan view.
The outline of the hole has an upwardly convex curved line portion ABC and an upwardly convex curved line portion DEF. Point B is the midpoint of the curved portion from A to C, and point E is the midpoint of the curved portion from D to F. In addition to the above contours, the outline of the hole has a straight part AJ parallel to the MD direction, a straight part JI parallel to the TD direction, a straight part ID parallel to the MD direction, and a straight part ID parallel to the MD direction. It has a parallel straight portion FH, a straight portion HG parallel to the TD direction, and a straight portion GC parallel to the MD direction.
The pore is an inverted U shape bounded by the ABCGHFEDIJA outline.

In the example shown in FIG. 3, curved portion ABC and curved portion DEF are both part of a circular arc. However, the film of the present invention is not limited to such a configuration, and the shapes of the curved portion ABC and the curved portion DEF are not particularly limited. It may be a part, a part of a hyperbola, or the like.
Also, in the example shown in FIG. 3, the contour of CGHF and the contour of DIJA consist of a plurality of straight line portions. However, the film of the present invention is not limited to such a configuration, and the contour of CGHF and the contour of DIJA include curved portions in addition to straight portions. It may be composed of a plurality of curved portions.

In the film of the first embodiment described above, the curved portion ABC and the curved portion DEF have the center of curvature on the same side (lower side of the paper surface), and the curved portion AB- C is located on the outside in the radius of curvature, and the curved portion DEF is located on the inside in the radius of curvature.
In the film of the second embodiment described above, the curved portion ABC and the curved portion AEC have the center of curvature on the same side (lower side of the paper surface), and the curved portion AB- C is located on the outside in the radius of curvature, and the curved portion DEF is located on the inside in the radius of curvature.
In the film of the second embodiment described above, the curved portion ABC and the curved portion DEF have the center of curvature on the same side (lower side of the paper surface), and the curved portion AB- C is located on the outside in the radius of curvature, and the curved portion DEF is located on the inside in the radius of curvature.

In any of the films of the first, second, and third embodiments described above, the outline of the hole includes two curved portions.
However, the film of the present invention is not limited to such a configuration. There may be a plurality of outer curved portions and a plurality of inner curved portions.

The present invention also includes embodiments other than the first embodiment, second embodiment, and third embodiment.

As another embodiment, for example, a part of the arc of the outer curved portion is not limited to an arc (half arc) with a central angle of 180 ° as in the first embodiment, but an arc with a central angle of more than 180 ° (see FIG. 4).
Such a central angle may be 210° or more, 240° or more, or the like, and may be 300° or less, 270° or less, or the like.
Various dimensions in the above embodiment may be determined in the same manner as in the first embodiment, and specifically may be determined as shown in FIG.

In another embodiment, for example, a part of the arc of the outer curved portion is not limited to an arc (semi-arc) with a central angle of 180° as in the first embodiment, and has a central angle of less than 180°. (see FIG. 5).
Such a central angle may be 60° or more, 90° or more, or the like, and may be 150° or less, 120° or less, or the like.
Various dimensions in the above embodiment may be determined in the same manner as in the first embodiment, and specifically may be determined as shown in FIG.

Furthermore, in other embodiments, for example, the outline of the hole may not include straight portions (see FIG. 6).
Specifically, as shown in FIG. 6, the two straight portions (the straight portion AD and the straight portion CF in FIG. 1) in the first embodiment are replaced with two curved portions (the two straight portions in FIG. 6). downwardly convex semicircular arc).
Various dimensions in the above embodiment may be determined according to the case of the first embodiment, and specifically may be determined as shown in FIG.

Furthermore, as another embodiment, for example, an outer straight portion may be provided between two outer curved portions, and an inner straight portion may be provided between two inner curved portions (see FIG. 7).
In the present embodiment, the outer curved portion and the inner curved portion are collectively referred to as a “curved portion set”, and the outer straight portion and the inner straight portion are collectively referred to as a “straight portion”. Also called group.
In other words, in the example of FIG. 7, two curved section sets may be provided so as to sandwich one straight section set.
Specifically, as shown in FIG. 7A, the outer curved portions in the first embodiment are divided into a first outer curved portion ABC and a second outer curved portion A'-B'-C'. , and the central portion of the original outer curved portion may be replaced with one outer straight portion CC'. Further, as shown in FIG. 7A, the inner curved portion in the first embodiment is divided into a first inner curved portion DEF and a first inner curved portion D'-E'-F'. , the central portion of the original inner curved portion may be replaced by one inner straight portion FF'.
Various dimensions in the above embodiment may be determined according to the case of the first embodiment, and specifically may be determined as shown in FIG. 7(B). FIG. 7(B) shows the dimensions of only the first outer curved portion.
Note that, as in the example of FIG. 7, when two curved section sets having the center of curvature on the same side are provided, the extension length LOe of the outer curved section and the length of both the outer curved section described above are Linear length LOs between ends, maximum distance DO between a straight line connecting both ends of the outer curved portion and the outer curved portion, extension length LIe of the inner curved portion, straight length LIs between both ends of the inner curved portion , the maximum distance DI between the straight line connecting both ends of the inner curved portion and the inner curved portion, and the maximum distance DOI between the outer curved portion and the inner curved portion may be the total for the two curved portion sets.
In addition, as in the example of FIG. 7, when two curved section sets having the center of curvature on the same side are provided, both LOe/LIe and DOI/DO for the two curved section sets are Good as an average.

Furthermore, as another embodiment, for example, an outer curved portion having a center of curvature on a side different from that of the two outer curved portions is provided between two outer curved portions, and the two inner curved portions are provided between the two inner curved portions. An inner curved portion having a center of curvature on a different side than the two inner curved portions may be provided (see FIG. 8).
In other words, in the example of FIG. 8, two curved section sets having the center of curvature on the same side are provided so as to sandwich one curved section set having the center of curvature on a different side from the two curved section sets. good too.
Specifically, as shown in FIG. 8(A), the upper curved portion consists of curves other than circular arcs, and upwardly convex curved portions ABC, and curved portions other than circular arcs, which extend downward. It includes a convex curved portion C-C' and an upwardly convex curved portion C'-B'-A' consisting of a curve other than a circular arc, and the lower curved portion consists of a curve other than a circular arc. An upwardly convex curved portion DEF, a downwardly convex curved portion FF' made of a curve other than a circular arc, and an upwardly convex curved portion D'-E'-F made of a curve other than a circular arc ' and .
In this example, the contour line of the hole further includes a straight portion AD and a straight portion A'-D'.
In this example, points C and C' are points of inflection for the outer curved portion, and points F and F' are points of inflection for the inner curved portion.
Furthermore, in this example, the length of the straight line connecting point B and point E is the DOI.
Various dimensions in the above embodiment may be determined according to the case of the first embodiment, and specifically may be determined as shown in FIG. 8(B). FIG. 8(B) shows the dimensions of only the hole portion defined by the curved portion ABC, the curved portion DEF, the straight portion AD, and the virtual line segment CF. show.
Note that, as in the example of FIG. 8, when two curved section sets having the center of curvature on the same side and one curved section set having the center of curvature on a different side from the two curved section sets are provided. In the above, the extension length LOe of the outer curved portion, the straight length LOs between both ends of the outer curved portion, the maximum distance DO between the straight line connecting both ends of the outer curved portion and the outer curved portion, Extension length LIe of inner curved portion, straight length LIs between both ends of inner curved portion, maximum distance DI between straight line connecting both ends of inner curved portion and inner curved portion, outer curved portion and inner curved portion Any of the maximum distances DOI to , may be summed over the three curve sets.
Also, as in the example of FIG. 8, when two curved section sets having the center of curvature on the same side and one curved section set having the center of curvature on a different side from the two curved section sets are provided. , both LOe/LIe and DOI/DO may be averaged over the three curve subsets.

(package)
The package of the present embodiment may be one in which an object to be packaged is wrapped with the film of the present embodiment.

The object to be packaged is preferably a solid or semi-solid, and particularly preferably a food product or a boxed lunch/prepared dish container containing the food product.
Examples of foods include meat, seafood, vegetables, fruits, noodles, and rice.
Examples of meat include cutlet and fried chicken. Seafood includes, for example, fried seafood. Vegetables include, for example, warm vegetables such as broccoli and carrots, and croquettes. Fruits include, for example, oranges and strawberries. Examples of noodles include ramen, udon, and the like. Examples of rice include pilaf and fried rice.

(roll body)
In the present embodiment, the film of the present embodiment described above may be wound around a core such as a paper tube to produce a roll body, and the roll body may be used to produce the packaging body of the present embodiment described above.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

Resins used in Examples, Reference Examples, and Comparative Examples are as follows.

LL1: ethylene-α-olefin copolymer (polymerized with a single-site catalyst), density: 0.913 g/cm ³ , MI: 2.0 g/10 minutes, main melting peak temperature: 113°C
LL2: ethylene-α-olefin copolymer (polymerized with a multisite catalyst), density: 0.916 g/cm ³ , MI: 2.0 g/10 minutes, main melting peak temperature: 120°C
LD1: high pressure low density polyethylene, density = 0.921 g/cm ³ , MI = 0.4 g/10 minutes

[Examples 1 to 3, Comparative Example 1, Reference Example 1]
After adding 1.0% by mass of diglycerin oleate to the resin composition having the composition shown in Table 1, it was extruded from an annular die as a single-layer or three-layer raw roll, cooled and solidified with cold water, and folded to a width of 120 mm. A tubular multilayer raw fabric having a thickness of 500 μm was produced. This was guided to an electron beam irradiation apparatus, irradiated with an electron beam accelerated to 500 kV, and subjected to cross-linking treatment so that the absorbed dose was 70 kGy. This is guided into a stretching machine to be reheated, passed between two pairs of differential nip rolls, air is injected to form bubbles, the heating temperature at the stretching start point is set to 140 ° C., and the length is 8 times in the machine direction. , and stretched at a magnification of 7 times in the width direction to obtain a heat-shrinkable film having an average thickness of 9 μm and a surface layer/inner layer/surface layer thickness ratio (%) of 15/70/15, respectively. . The 100° C. shrinkage of the film was MD/TD=15%/25%.

The heat-shrinkable films of Examples 1 to 3 were perforated as follows.
The film was passed between a bladed roller and a co-rotating receiving roller to form cuts and perforations of size and spacing as shown in Table 1. At this time, the shape of the hole became an arch shape. The shapes of the holes in Examples 1 to 3 were as shown in Table 1.
The heat-shrinkable films of Examples 4 and 5 were perforated in the same manner as in Examples 1-3. The shape of the hole in Example 4 was a crescent shape, and the shape of the hole in Example 5 was an inverted U shape.

The heat-shrinkable film of Comparative Example 1 was perforated by passing the film between a diamond roll and a receiving roll to form fine holes including many non-through holes, and then passing it between the dielectric roll and the electrode. Perforations having sizes as shown in Table 1 were formed by penetrating blind holes with arc discharge. At this time, the shape of the perforations was substantially circular.

In the examples and the comparative examples, the areas and positions of the perforated regions in the films were all the same.
The perforated portion was the central portion of the film, and the area of the region was 10% of the film area.

The heat-shrinkable film of Reference Example 1 was perforated by piercing the film with needle-like projections with a diameter of 1.0 mm to a length of 5 mm to form perforations having the sizes shown in Table 1. Five perforations were formed at intervals of 15 mm in the TD direction and at intervals of 15 mm in the MD direction at the central portion of the film.

The dimensions of the holes in Examples, Reference Examples, and Comparative Examples were as shown in Table 1.

The measurement methods used in Examples, Reference Examples, and Comparative Examples are described below.

(1) Hole diameter and hole shape before heat treatment By punching, arbitrarily select 10 holes in the film formed, and measure the 10 holes with a micrometer (manufactured by Keyence Corporation, product name: main unit “VHX -5000", lens "VH-ZST"), measure the maximum diameter (in the arch-shaped hole in the example below, measure the length of the straight line between both ends of the curve located on the outside of the upward convex , the longest hole diameter was measured for the circular holes in the following examples), and the average value was taken as the hole diameter (μm) of the perforations before the heat treatment. In addition, the shape of the ten holes before the heat treatment was observed in plan view.

(2) Hole diameter and hole shape after heat treatment The perforated film was slit into a size of 550 mm in width and 1000 m in length, and after heat shrinking into a wooden frame of size 15 cm × 30 cm, the area ratio was reduced by 10%. , the temperature in a shrink tunnel (K.U. System: FB800) was set to 140°C, the residence time was set to 3 seconds, and the film was passed through the wooden frame for heat treatment. Randomly select 10 of the holes in the central part of the film after heat treatment, measure the diameter of the 10 holes as described in "(1) Hole diameter before heat treatment", and take the average value as the perforation after heat treatment. pore size (μm). In addition, the shape of the ten holes after the heat treatment was observed in a plan view.

(3) Packaging evaluation The film is slit to a width of 550 mm, and using “FW-3451A-αV (trade name)” manufactured by Fuji Machinery Co., Ltd., “RF Pork Kakudon 17 (trade name)” manufactured by CP Kasei Co., Ltd. ”, 30 packs containing about 200 g of cooked rice at 20 ° C are pillow-packaged, and each film is set to a tunnel temperature of 140 ° C and a passing time of 3 seconds to perform heat treatment. made an evaluation.
The pillow packaging was carried out while changing the conditions of the air volume of the fan. As the air volume of the fan changes from 30 Hz to 60 Hz, there is an effect equivalent to slowing the line speed.
(packaging finish)
◯: The package has no small wrinkles or residual corners, and no air pockets remain.
Δ: Small wrinkles and residual corners are present on the package, but no air pockets remain.
x: The film has not completely shrunk and air pockets remain.

(4) Insect Penetration Test A bento box package in which pasta in a commercially available container with a steam port is heat-shrink wrapped with each film is placed in a nylon goose cage (30 cm x 30 cm x height 30 cm) in a room adjusted to 25°C. The cage was set on the floor inside the cage, and 100 Okimon flea flies were released into the cage to start the test. Twenty-four hours after releasing the insects, the number of invading insects in each package was investigated.

(5) Appearance evaluation Paste a sticker printed with 8 point characters on the lid of “RF Pork Kakudon 17 (trade name)” manufactured by CP Kasei Co., Ltd., and put about 200 g of rice at 20 ° C inside. The appearance was evaluated as follows depending on whether or not the letters on the top surface of the sample heat-shrink-wrapped with each film were easily recognizable when viewed at an angle of 20° to the top surface.
◯: Characters can be distinguished without any problem.
Δ: Characters are a little difficult to distinguish.
x: Characters are very difficult to distinguish.

In Examples 1 to 3, the packaging finish and the insect penetration test were good.
In Comparative Example 1, there was no condition for a good finish of the package, and in Comparative Example 3, the package was finished without fine wrinkles and corners, but the density of the perforations was extremely high, making the perforations conspicuous and unsuitable as a product for sale. It was something.
In Reference Example 1, the hole diameter of the perforations after heat treatment was large, and many insects penetrated in the insect penetration test after packaging.

INDUSTRIAL APPLICABILITY The present invention can provide a film capable of producing a good-looking package without lowering the packaging speed and reliably preventing entry of small insects.

LOe Extended length of the outer curved portion LOs Straight length between both ends of the outer curved portion DO Maximum distance between the straight line connecting both ends of the outer curved portion and the outer curved portion LIe Extended length of the inner curved portion LIs Straight length between both ends of the inner curved part DI Maximum distance between the straight line connecting both ends of the inner curved part and the inner curved part DOI Maximum distance between the outer curved part and the inner curved part S Hole area

Claims (15)

A film having holes,
The outline of the hole is
a curved portion AC located on the outer side in the curvature radial direction;
a curved portion DF located inside in the curvature radial direction and having a center of curvature on the same side as the curved portion AC;
a line segment AD connecting one terminal point A of the curved portion AC and the terminal point D of the curved portion DF closest to the terminal point A;
a line segment CF connecting the other terminal point C of the curved portion AC and the terminal point F of the curved portion DF closest to the terminal point C;
It is an arch shape of ACFDA surrounded by
the area of the pores is 100 μm ² to 45000 μm ² ,
A film characterized by: A film having holes,
The outline of the hole is
a curved portion AC located on the outer side in the curvature radial direction;
a curved portion DF located inside in the curvature radial direction and having a center of curvature on the same side as the curved portion AC;
A line segment AJ extending from the end point A in a direction substantially perpendicular to the curvature radius 1 passing through one end point A of the curved portion AC and away from the curved portion AC; one of the curved portions DF A line segment DI extending from the terminal point D in a direction substantially perpendicular to the curvature radius 2 passing through the terminal point D of and in a direction away from the curved portion DF; and a line segment connecting the point J and the point I a polygonal line AJID consisting of a line segment JI that is substantially parallel to a straight line connecting the terminal point A and the terminal point D;
a line segment CG extending from the terminal point C in a direction substantially perpendicular to the curvature radius 3 passing through the other terminal point C of the curved portion AC and away from the curved portion AC; the other of the curved portion DF; A line segment FH extending from the end point F in a direction substantially perpendicular to the curvature radius 4 passing through the end point F of and in a direction away from the curved portion DF; and a line segment connecting the point H and the point G a polygonal line CGHF consisting of a line segment GH which is substantially parallel to a straight line connecting the terminal point C and the terminal point D;
is an inverted U shape of ACGHFDIJA surrounded by
The area of the hole is 100 μm ² ~45000μm ² is
A film characterized by: 3. The film according to claim 1 , wherein the extending length of the curved portion located on the outer side in the curvature radial direction is 100 μm or more and 600 μm or less. 4. The film according to any one of claims 1 to 3 , wherein the linear length between both ends of the curved portion located on the outer side in the curvature radius direction is 100 µm or more and 300 µm or less. 5. Any one of claims 1 to 4 , wherein a maximum distance between a straight line connecting both ends of the curved portion located on the outer side in the curvature radial direction and the curved portion located on the outer side in the curvature radial direction is 1 μm or more and 300 μm or less. The film according to item 1. The film according to any one of claims 1 to 5 , wherein the extending length of the curved portion located inside in the radius direction of curvature is 100 µm or more and 600 µm or less. The film according to any one of claims 1 to 6 , wherein the linear length between both ends of the curved portion located inside in the radius direction of curvature is 100 µm or more and 300 µm or less. 8. The maximum distance between a straight line connecting both ends of the curved portion positioned inside in the radius direction of curvature and the curved portion positioned inside in the radius direction of curvature is 1 μm or more and 300 μm or less. The film according to item 1. The film according to any one of Claims 1 to 8 , wherein the maximum distance between the curved portion located outside in the radial direction of curvature and the curved portion located inside in the radial direction of curvature is 1 µm or more and 300 µm or less. The film according to any one of claims 1 to 9, wherein the pores deform into substantially circular shapes when the film is heated at 140°C for 3 seconds. The film according to any one of claims 1 to 10, wherein when the film is heated at 140°C for 3 seconds, the pore enlargement ratio before and after the heating is 100 to 200%. 12. The film according to any one of claims 1 to 11, wherein the perforated processed portion has a density of 10 to 100 holes/cm ² . A boxed lunch/prepared dish package, characterized in that the boxed lunch/prepared dish is wrapped with the film according to any one of claims 1 to 12. A cut vegetable package, characterized in that cut vegetables are wrapped with the film according to any one of claims 1 to 12. A roll body, characterized in that the film according to any one of claims 1 to 12 is wound around a paper tube.

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