JP6888657B2 - Fruit and vegetable freshness preservation packaging container, fruit and vegetable packaging and fruit and vegetable freshness preservation method - Google Patents

Description

The present invention relates to a fruit and vegetable freshness-preserving packaging container, a package containing fruits and vegetables, and a method for maintaining the freshness of fruits and vegetables. More specifically, the present invention relates to a fruit and vegetable freshness-preserving packaging container, a fruit and vegetable-containing package in which fruits and vegetables are packaged in the container, and a method for maintaining the freshness of fruits and vegetables using the container.

Fruits and vegetables such as vegetables and fruits maintain their respiratory action even after being harvested. Therefore, during storage, distribution or storage after harvesting, the respiration of the fruits and vegetables themselves consumes energy and causes deterioration of freshness.
Therefore, studies have been conducted so far to suppress deterioration of freshness of fruits and vegetables by packaging fruits and vegetables with an appropriate packaging material (for example, a resin film).

As an example, Patent Document 1 describes a moisture-permeable / breathable packaging material in which a polyethylene terephthalate (PET) -based non-woven fabric having a basis weight of 30 to 70 g / m ^{2, a printing layer, and a polyolefin-based resin layer are sequentially laminated.} Has been done. A feature of this packaging material is that a plurality of holes penetrating the polyolefin-based resin layer are formed in a predetermined region of the polyolefin-based resin layer.

As another example, Patent Document 2 describes a packaging material in which holes are provided in a resin film and a "freshness-preserving label" for controlling gas permeability is attached to the holes. The label for maintaining freshness here is formed by superimposing a microporous film having a pore diameter in the range of 0.01 to 0.5 μm and a perforated film having an average pore diameter in the range of 100 to 500 μm and heat-bonding them. It is characterized in that an adhesive layer is provided around the outer surface of the microporous film or the perforated film.

Japanese Unexamined Patent Publication No. 2006-231723 Japanese Unexamined Patent Publication No. 10-262548

As in Patent Documents 1 and 2, it is known to manufacture a fruit and vegetable freshness-preserving packaging container using a resin film having adjusted air permeability, and further, to wrap fruits and vegetables using the fruit and vegetable freshness-preserving packaging container. ing.

It is preferable that the fruit and vegetable freshness-preserving packaging container not only retains the freshness of fruits and vegetables by appropriate air permeability but also has practically good characteristics as a “packaging container”.
From one viewpoint, (i) the opening can be closed with sufficiently strong strength by heat sealing, and (ii) when opening the container, the heat sealing part can be easily peeled off and opened. A holding packaging container is practically preferable.
Further, as another viewpoint, a chuck (zipper) may be attached to the opening of the fruit and vegetable freshness-preserving packaging container. Normally, when a chuck (zipper) is attached to a fruit and vegetable freshness-preserving packaging container by heat fusion, it is required that the chuck (zipper) portion is difficult to remove.
From the viewpoint of these practical characteristics as a packaging container, there is room for improvement in the packaging material described in Patent Document 1.

The present invention has been made in view of such circumstances. An object of the present invention is to provide a fruit and vegetable freshness-preserving packaging container having practically good properties.

As a result of diligent studies, the present inventors have completed the inventions provided below and solved the above problems.

According to the present invention
A fruit and vegetable freshness-preserving packaging container made of a resin film having holes.
The diameter of the hole is less than 1000 μm
The microcrystal size of the resin film determined by the X-ray diffraction method is 2.8 to 3.0 nm, and the degree of orientation determined by the X-ray diffraction method is 70 to 85%.
The resin film is a fruit and vegetable freshness-preserving packaging container containing stretched polypropylene (excluding those with a breathable material covering the holes).
Is provided.

Further, according to the present invention.
A package containing fruits and vegetables is provided in which fruits and vegetables are packaged by the above-mentioned fruit and vegetable freshness-preserving packaging container.

Further, according to the present invention.
A method for preserving freshness of fruits and vegetables is provided, in which fruits and vegetables are packaged using the above-mentioned packaging container for preserving freshness of fruits and vegetables.

According to the present invention, a fruit and vegetable freshness-preserving packaging container having practically good properties is provided.

It is sectional drawing of the manufacturing apparatus for demonstrating the method of perforating a resin film. It is an enlarged sectional view of the main part of the manufacturing apparatus for demonstrating the method of drilling a resin film. It is a perspective view of the manufacturing apparatus for demonstrating the method of perforating a resin film.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The drawings are for illustration purposes only. The shape and dimensional ratio of each member in the drawing do not necessarily correspond to the actual article.

In the present specification, the term "abbreviation" means to include a range in consideration of manufacturing tolerances, assembly variations, etc., unless otherwise specified explicitly.
In the present specification, the notation "XY" in the description of the numerical range means X or more and Y or less unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass or more and 5% by mass or less".
The notation "(meth) acrylic" herein represents a concept that includes both acrylic and methacryl. The same applies to similar notations such as "(meth) acrylate".

In the present specification, "fruit and vegetable freshness-preserving packaging container" may be simply referred to as "container".

<Packaging container for maintaining freshness of fruits and vegetables>
The fruit and vegetable freshness-preserving packaging container of the present embodiment is made of a resin film having holes.
The shape of the fruit and vegetable freshness-preserving packaging container of the present embodiment is typically bag-shaped. Of course, the shape of the fruit and vegetable freshness-preserving packaging container of the present embodiment may be a shape other than a bag shape as long as the fruit and vegetable can be packaged.

In the fruit and vegetable freshness-preserving packaging container of the present embodiment, the diameter of the pores of the resin film is less than 1000 μm. This hole allows for adequate ventilation between the inside and outside of the container. Then, the deterioration of freshness of the fruits and vegetables stored in the container can be suppressed.

In the fruit and vegetable freshness-preserving packaging container of the present embodiment, the microcrystal size of the resin film determined by the X-ray diffraction method is 2.5 to 3.5 nm.
The "microcrystal size" is obtained, for example, by applying the data obtained by X-ray diffraction measurement of a resin film to the following mathematical formula known as Scherrer's formula in the polymer field. As the measurement surface, for example, when the resin film is polypropylene, the (111) surface can be adopted (of course, other surface may be used). For the measurement position (position to irradiate X-rays) on the measurement surface, select a position sufficiently distant from the hole.

D = 0.94λ / (βcosθ)
D: Microcrystal size λ: Wavelength of X-ray used for measurement (1.54 Å for Cu-Kα ray)
β: Half width of measurement surface peak (unit: rad)
θ: Bragg angle on the measurement surface (unit: rad)

Incidentally, when the microcrystal size is determined by the X-ray diffraction method, X-rays are usually incident from the ND direction (Normal Direction) of the resin film.

In general, the melting behavior of a polymer is not determined only by the primary structure of the polymer, but also depends on the crystallization state of the polymer.
It is presumed that the microcrystal size of the resin in the resin film is 3.5 nm or less, so that the resin "quickly" responds to the heat during heat sealing and melts. Therefore, it is presumed that sufficient heat sealability can be obtained and that the chuck (zipper) can be attached with sufficient strength.
Further, since the microcrystal size of the resin in the resin film is 2.5 nm or more, the resin does not "melt too much" within the temperature and time of the heat seal that is usually performed, and the resin is excessively melted. And it is presumed that the subsequent sticking is suppressed. Therefore, it is presumed that the heat-sealed portion can be easily peeled off with an appropriate force.
That is, by forming the fruit and vegetable freshness-preserving packaging container with a resin film having a microcrystal size of 2.5 to 3.5 nm, practical merits such as heat sealability can be obtained.

In addition, by constructing a fruit and vegetable freshness-preserving packaging container with a resin film having a microcrystal size of 2.5 to 3.5 nm, holes of substantially the same size / shape should always be provided if the drilling conditions are constant. You can get the additional benefit of being able to. That is, when holes are provided in the resin film by the laser drilling method described later, the microcrystal size is 2.5 to 3.5 nm, so that holes having a constant diameter and shape can be formed if the laser irradiation conditions are constant. It will be easier to install. This advantage is particularly noticeable when the diameter of the hole is relatively small.
If the drilling conditions are constant, holes of substantially the same size / shape can be provided at all times, so that the freshness retention of fruits and vegetables can be further enhanced. For example, the freshness retention of fruits and vegetables can be enhanced with each of the mass-produced containers.

As a reminder, the above description includes speculation by the inventor. Moreover, the present invention is not limitedly interpreted by the above description including speculation.

In order to make the microcrystal size of the resin film determined by the X-ray diffraction method 2.5 to 3.5 nm, it is preferable to form an appropriate material under appropriate conditions. Details of the material and film forming conditions will be explained later. Of course, the method of setting the crystallite size to 2.5 to 3.5 nm is not limited to the method described in the present specification. A known method can be appropriately used in the production of the resin film.

Hereinafter, a specific description of the fruit and vegetable freshness-preserving packaging container of the present embodiment will be continued.

(Resin film)
-Material The material of the resin film is not particularly limited. A resin film having a microcrystal size of 2.5 to 3.5 nm and capable of packaging fruits and vegetables can be appropriately used.
The resin film may be stretched or unstretched. From the viewpoint of optimizing the crystallite size, it is preferably stretched.

The resin film is selected from the group consisting of polyethylene, ethylene copolymer, polypropylene, polyvinyl chloride, polystyrene, (meth) acrylic resin, polyester resin and polyamide resin because of availability, cost, ease of drilling, etc. It is preferable to include plastic.
The resin film may contain only one kind of resin, or may contain two or more kinds of resins.

In particular, the resin film preferably contains at least one selected from the group consisting of stretched polypropylene and linear low density polyethylene.

The polypropylene of stretched polypropylene may be any of a homopolymer of propylene, a block copolymer of propylene, a random copolymer of propylene and the like. Examples of propylene random copolymers or block copolymers include random copolymers or block copolymers of propylene monomers and α-olefins having 2 or 4 to 10 carbon atoms. Of these, a random copolymer of propylene and ethylene or a block copolymer is preferable.
The "stretching" of stretched polypropylene is usually biaxial stretching. The draw ratio is not particularly limited, but can be, for example, about 2 to 5 times in each of the MD direction and the TD direction.

Linear low density polyethylene (L-LDPE) is usually a copolymer of ethylene and a small amount of α-olefin. The type of α-olefin is not particularly limited. Typical α-olefins include α-olefins having 3 to 10 carbon atoms, such as 1-butene, 1-hexene, 4-methylpentene-1, 1-octene, and the like.

-Additional components, contact angle The resin film may contain additives such as an antifogging agent and an anticondensation agent in addition to the resin. By including an appropriate additive in the resin film, the resin film can be imparted with desirable properties for packaging and storage of fruits and vegetables.
Specific examples of the antifogging agent include glycerin laurate, diglycerin laurate, decaglycerin laurate, glycerin monostearate, sorbitan stearate and the like.

In terms of anti-fog property and anti-condensation property, the contact angle of the inner surface of the container with water is preferably 3 to 60 °, more preferably 10 to 59 °, still more preferably 20 to 58 °.
The contact angle may be adjusted by an additive such as an anti-fog agent or an anti-condensation agent, by applying some treatment to the surface of the resin film, or both of these. Good. In terms of convenience and certainty of effect, the resin film preferably includes antifogging property.

For the contact angle with water, for example, a commercially available contact angle meter (for example, DROPMASTER-501 manufactured by Kyowa Interface Science Co., Ltd.) is used, and 2 μL of purified water is dropped on the surface to be measured by the sessile drop method for 7 seconds. It can be obtained by measuring the subsequent water contact angle.

-Orientation degree The orientation degree of the resin film determined by the X-ray diffraction method is preferably 70 to 85%, more preferably 73 to 84%. It is considered that when the degree of orientation is an appropriate value, the melting behavior of the resin due to heat during heat sealing is further controlled, and the heat sealing property and the peeling property of the heat sealing portion are further enhanced.
When the degree of orientation is determined by the X-ray diffraction method, X-rays are usually incident from the TD direction (Transverse Direction) of the resin film. As for the measurement position (position to irradiate X-rays), a position sufficiently distant from the hole is selected.

The degree of orientation (%) is usually calculated by the formula {(180-Wh) / 180} × 100. Wh is the full width at half maximum (°) of the crystalline peak.

-Thickness The thickness of the resin film is preferably 15 to 50 μm, more preferably 20 to 45 μm. When the thickness of the resin film is 15 μm or more, it is easy to increase the strength of the container. When the thickness of the resin film is 50 μm or less, the flexibility (suppleness) of the container can be maintained.

-Method of manufacturing a resin film The method of obtaining a resin film is not particularly limited. Examples of the method for obtaining the resin film include known methods such as extrusion, inflation, and calendar ring.
The resin film may be a single layer or a multilayer of two or more layers. As a method for obtaining the multilayer film, known methods such as dry lamination, extrusion lamination, coextrusion, and coating can be appropriately used.

As a specific example, when polypropylene is used as a raw material, a resin film having a microcrystal size of 2.5 to 3.5 nm can be easily produced by forming a film of polypropylene by the following procedure. In the following, the roll temperature of the roll stretching machine is particularly important.
(1) The raw material polypropylene is melted at 200 to 230 ° C.
(2) The molten polypropylene is extruded from the die and subsequently stretched by a roll stretching machine for about 10 seconds in the MD direction and the TD direction by about 2 to 5 times, respectively.
At this time, the temperature of the roll of the roll stretching machine is set to, for example, 65 to 95 ° C., preferably about 75 to 95 ° C.
(3) The stretched film is brought into contact with a cooling roll set at about 20 ° C. to cool it. The cooling time is, for example, about 1 to 2 seconds.
(4) The cooled film is wound up with a take-up roll at room temperature.

As a reminder, if a commercially available resin film has a microcrystal size of 2.5 to 3.5 nm, it may be used as the resin film.

(Hole)
In the fruit and vegetable freshness-preserving packaging container of the present embodiment, the holes of the resin film are typically through holes.

-Number of holes, density, etc. The resin film may have at least one hole, but preferably has a plurality of holes. That is, the fruit and vegetable freshness-preserving packaging container of the present embodiment is preferably composed of a resin film having a plurality of holes. As a result, it is easy to obtain appropriate air permeability according to the type of fruits and vegetables to be packaged.
More specifically, the number of holes is, for example, 1 to 500, preferably 2 to 300 per container.

As another aspect, the pores are present on the outer surface of the fruit and vegetable freshness preserving packaging container at a density of ^{preferably 1 to 1500 pieces / m 2, more preferably 2 to} 1000 pieces / m ^2. The "density" here can be obtained by dividing the number of holes in the container by the outer surface area of the bag.

From a further viewpoint, in the fruit and vegetable freshness-preserving packaging container of the present embodiment, it is preferable to appropriately adjust the "area" with holes, that is, the perforated area. Specifically, when the total opening area of the hole provided in the container S _h, the area of the outer surface of the container was S _t,
Formula: ( _Sh / _St ) x 100
In in being defined aperture area ratio (%) is preferably a ^{1.0 × 10 -6 ~1.0 × 10 -2} , 1.0 × 10 -5 ~1.0 × 10 -3 More preferably.

-Pore diameter The diameter of the hole may be less than 1000 μm, but is preferably 950 μm or less, more preferably 500 μm or less, still more preferably 300 μm or less, and particularly preferably 200 μm or less.
The lower limit of the hole diameter is preferably 30 μm or more, more preferably 50 μm or more.

When the shape of the hole cannot be regarded as substantially circular, the diameter of a perfect circle having the same area as the opening area of the hole (diameter equivalent to a perfect circle) is adopted as the diameter of the hole.
When the diameter of a hole on the outer surface side and the diameter on the inner surface side are different, it is preferable that the diameter on the outer surface side is in the above numerical range.

As one aspect, when the fruit and vegetable freshness-preserving packaging container of the present embodiment has a plurality of holes, the diameters of all the holes (in the case of a large number of holes, five randomly selected holes) are within the above numerical range. It is preferable that it fits in. By not having holes that are too large or too small, gas permeation can be controlled more appropriately, and a better effect of maintaining the freshness of fruits and vegetables can be obtained.

(Container shape, size, etc.)
The shape of the fruit and vegetable freshness-preserving packaging container of the present embodiment is not particularly limited as long as the fruit and vegetable can be packaged. The fruit and vegetable freshness-preserving packaging container of the present embodiment is typically bag-shaped. The bag shape is, for example, a quadrangle (rectangle, square, etc.).
When the shape of the fruit and vegetable freshness-preserving packaging container of the present embodiment is bag-shaped, the size thereof can be appropriately set according to the shape, size, number, and the like of the fruit and vegetable to be packaged. As an example, in the case of packaging fruits and vegetables for general consumers, the size of the bag is, for example, about 115 mm × 150 mm to 260 mm × 380 mm.

(Other supplements)
Arbitrary characters and patterns may be printed on the fruit and vegetable freshness-preserving packaging container of the present embodiment. Printing may take place at any stage of the manufacture of the container. The printing method, the type of ink used for printing, and the like may be appropriately selected according to the purpose of printing.

<Manufacturing method of fruit and vegetable freshness preservation packaging bag>
The fruit and vegetable freshness-preserving packaging container of the present embodiment can be manufactured, for example, by (1) a resin film preparation step, (2) a perforation step of forming holes in the resin film, and (3) a bag making step. The order of (2) and (3) is not particularly limited, but from the viewpoint of productivity, it is preferable to perform (3) after (2).
Further, for example, in the bag making step (3), a step of attaching a means for closing the opening, for example, a chuck (zipper) to the resin film may be performed.
Hereinafter, these steps will be described.

(1) Preparation Step of Resin Film A resin film having a microcrystal size of 2.5 to 3.5 nm, which is obtained by the above-mentioned X-ray diffraction method, is prepared. The material, manufacturing method, etc. of the resin film are as described above. Therefore, a new description will be omitted.

(2) Drilling step A hole is provided in the resin film prepared in the preparation step of (1). Examples of the method for providing the holes include laser machining, punching, and hot needle machining. Of these, laser machining is preferable from the viewpoints of ease of controlling the properties of the holes, ease of maintenance of the manufacturing apparatus (since the holes can be provided in the film in a non-contact manner, it is difficult to get dirty) and the like.

An example of a drilling method by laser machining will be described in detail.
1 and 2 are cross-sectional views of a manufacturing apparatus for explaining a laser drilling method. Further, FIG. 3 is a perspective view of a main part. Hereinafter, description will be made with reference to these figures.

According to the manufacturing apparatus of FIG. 1, when the resin film 12 unwound from the unwinding roll 11 passes between the laser irradiating device 13 and the rotation support roll 14, the laser irradiating device 13 transmits the beam of the pulse laser to the resin film. 12 can be irradiated. By doing so, the resin film 12 can be provided with holes having substantially the same shape as the irradiated beam.
The resin film 12 provided with holes by this method is wound by a winding roll 15. Two guide rolls 16 can be provided before and after the rotation support roll 14.

The upper end of the rotation support roll 14 can be located above the line connecting the upper ends of the two guide rolls 16. As a result, the resin film 12 can be pressed against the rotation support roll 14 so as to be in close contact with the rotation support roll 14, the laser irradiation position can be positioned, and vertical wrinkles can be prevented from occurring.

Further, in the manufacturing apparatus of FIG. 1, the unwinding roll 11 and the winding roll 15 can be provided via the rotation support roll 14. In the manufacturing apparatus of FIG. 1, the guide roll 16 can be provided between the rotation support roll 14 and the unwinding roll 11, and between the rotation support roll 14 and the take-up roll 15, respectively. Further, the floating roll 17 can be provided between the unwinding roll 11 and the guide roll 16 and between the guide roll 16 and the winding roll 15, respectively. By doing so, an appropriate tension can be applied to the resin film 12 by the floating roll 17.

The laser irradiation device 13 is provided with a compressed gas introduction path 18, and during laser irradiation, the compressed gas can be blown onto the resin film 12 from the nozzle tip 19 (see FIG. 3) along the laser beam.

FIG. 2 is an enlarged cross-sectional view of a main part of the laser irradiation apparatus 13 in the manufacturing apparatus shown in FIG.
As shown in FIG. 2, the resin film 12 can be run below the nozzle tip 19 of the laser irradiation device 13.

Since the pulsed laser 20 passes through the light guide path 21 and is focused by the emitting optical unit (lens) 22, it becomes a conical beam 23 and can irradiate the resin film 12 from the nozzle tip 19. At this time, the inner diameter of the nozzle tip 19 is made larger than the beam diameter of the passing pulse laser 20. Further, it is preferable that the focal position of the pulsed laser 20 focused by the emitting optical unit (lens) 22 is a position slightly outside the film from the surface of the resin film 12 opposite to the laser incident surface.
By intentionally setting the focal position to the position outside the film, it is easy to obtain holes having different opening areas on the inner surface and the outer surface.

By irradiating the conical beam 23, the beam irradiation portion of the resin film 12 is melted, decomposed, and volatilized, so that the hole 24 is formed. Further, usually, at this time, a "hump" around the hole can be formed by melting the resin film 12 or the like.

The pitch of the holes 24 formed in the resin film 12 can be adjusted by the traveling speed of the resin film 12 and the pulse frequency of the pulse laser 20. Since one laser irradiation device can normally open 20 to 1000 holes 24 per second, the traveling speed of the resin film 12 can be increased and high productivity can be achieved.

The shape of the holes 24 formed in the resin film 12 is substantially the same as that of the conical beam 23 passing through the resin film 12, and holes having a substantially constant shape can always be formed. The conical trapezoidal hole can be made closer to a cylindrical shape by increasing the focal length of the exit optical unit (lens) 22.
By appropriately moving the laser irradiation device 13 during the laser irradiation, the shape of the hole may be a substantially elliptical shape instead of a substantially circular shape.

As described above, the compressed gas introduction path 18 is provided in the vicinity of the nozzle tip 19 of the light guide path 21 in the laser irradiation device 13. By doing so, the compressed gas can be blown along the laser beam onto the resin film 12 during the laser irradiation.

The flow rate of the compressed gas is preferably set to 2 to 10 m / s at the nozzle tip 19 so that decomposition products generated by drilling do not invade from the nozzle tip 19 and contaminate the exit optical unit (lens) 22. It is more preferable to set it to 3 to 6 m / s.

The compressed gas is not particularly limited, and for example, in addition to compressed air, an inert gas such as nitrogen gas or carbon dioxide gas can be used. Compressed air is not dangerous in handling and is also advantageous in terms of cost. The inert gas can suppress the oxidation of the decomposition products of the plastic film and reduce soot, charring, blackening and the like.

In this drilling method, the surface of the resin film 12 opposite to the laser incident surface is brought into contact with the rotary support roll 14, and the resin film 12 is supported by the rotary support roll 14.
It is preferable that the rotation support roll 14 is provided with a groove 25 corresponding to the laser irradiation position, for example, as shown in FIG. As a result, the decomposed product of the resin film 12 can be volatilized from the side opposite to the laser incident surface.

The rotation support roll 14 shown in FIG. 3 has five grooves 25. When five laser irradiation devices are used together with such a rotation support roll 14, five rows of holes can be provided in the resin film 12.

The type of laser light source is not particularly limited. For example, a ruby laser, a neodymium YAG laser, a neodymium glass laser, a carbon dioxide gas laser and the like can be mentioned. Among these, the carbon dioxide gas laser can be particularly preferably used because it has high energy efficiency, high output, and easy heat removal.

According to the drilling method described here, holes can be formed in the resin film at high speed and with high productivity. Since the shape of the hole is determined by the beam shape of the pulse laser, it is possible to always make a hole having a substantially constant shape.
In addition, most of the resin film material in the portion punched by the laser is decomposed and volatilized, and is blown off by the compressed gas. Therefore, the emission optical unit (lens) of the laser irradiation device is not contaminated by decomposition products.
Further, by selecting the radix of the laser irradiation device and adjusting the period of the pulse laser and the traveling speed of the resin film, the position and density of the holes can be changed to desired values.

According to the drilling method described here, the diameter of the hole and the position of the hole can be highly controlled. The selection of the film material and the selection of the laser processing conditions when producing the bag will be described in more detail in Examples described later.

(3) Bag-making process As for the bag-making method, a known method can be applied without particular limitation.
For example, as described in the examples below, two perforated resin films cut into a quadrangle of an appropriate size are prepared, and they are overlapped and heat-sealed on three of the four sides of the quadrangle. By doing so, a packaging container (bag) can be manufactured. The seal width of the heat seal is, for example, about 10 mm.
Of course, any other method can be applied to make the fruits and vegetables into a packageable shape. For example, a container may be manufactured from a resin film by using a fusing method, which is one of the industrial bag making methods.

In the bag making step, a means for closing the opening, for example, a chuck (zipper) may be attached in the vicinity of the opening of the container. The mounting method is as follows, for example.
First, a male chuck tape and a female chuck tape are attached to the inside of each of the two resin films facing each other by heat fusion. The male and female chuck tapes are usually made of thermoplastic resin.
Then, the four sides of the resin film are heat-sealed and / or melted to obtain a container (bag) of a desired size.

Regarding the method for manufacturing a container with a chuck (zipper), for example, Japanese Patent Application Laid-Open No. 2000-226042, Japanese Patent Application Laid-Open No. 2011-2000507, Japanese Patent No. 4787833 and the like can be referred to. There is nothing special about attaching the chuck (zipper) near the opening of the container, and a known technique may be appropriately applied.
In this embodiment, the crystallite size of the resin film is appropriate. As a result, the male chuck tape or female chuck tape and the resin film can be fused sufficiently strongly.

<Packaging with fruits and vegetables, how to keep the freshness of fruits and vegetables>
By packaging (preferably sealing) fruits and vegetables with the fruit and vegetable freshness-preserving packaging container of the present embodiment, a package containing fruits and vegetables can be produced. Further, by packaging the fruits and vegetables using the fruit and vegetable freshness-preserving packaging container of the present embodiment, the freshness of the fruits and vegetables can be maintained (deterioration of the fruits and vegetables is suppressed).

As an example, first, the fruit and vegetable freshness-preserving packaging container of the present embodiment is prepared, and an appropriate amount of fruits and vegetables is stored in the internal space thereof. After that, the opening of the container is heat-sealed (heat-sealed) to form a heat-sealed portion. The seal width of the heat-sealed portion is typically about 10 mm. By such a procedure, it is possible to obtain a package containing fruits and vegetables in which fruits and vegetables are packaged. Then, the freshness of the packaged fruits and vegetables can be maintained (deterioration of the fruits and vegetables can be suppressed).

The opening may be closed by an adhesive tape, a rubber band, a string, or the like instead of a heat seal. Further, when the container itself is provided with a means (for example, a chuck) for closing the opening, the opening may be closed by the means. In short, any closing method may be used as long as the gas entry and exit through the opening is sufficiently restricted.

The fruits and vegetables that can be packaged are not particularly limited. Specific examples of fruits and vegetables include oba, spinach, komatsuna, mizuna, mibuna, asparagus, Chinese cabbage, lettuce, thyme, sage, parsley, Italian parsley, rosemary, oregano, lemon balm, turnip, lavender, salad burnet, rams ear, rocket. , Dandy Lion, Nastatum, Basil, Arugula, Creson, Moroheiya, Celoli, Kale, Negi, Cabbage, Chinese cabbage, Shungiku, Saladana, Sanchu, Fuki, Nabana, Chingensai, Mitsuba, Seri, Mekabetsu, Broccoli, Califlower, Myoga Carrot, Gobo, Radish, Turnip, Sweet potato, Potato, Nagaimo, Yam, Satoimo, Jinenjo, Yamatoimo, Peaman, Paprika, Shishito, Cucumber, Eggplant, Tomato, Mini tomato, Pumpkin, Bitter gourd, Okura, Sweet corn, Edamame, Sayaendo Examples include Chinese cabbage, arugula, and fungus mushrooms. It is also effective for fruits such as citrus fruits, apples, pears, grapes, blueberries, persimmons and strawberries, and cut flowers.
The fruits and vegetables may be cut vegetables, so-called cut vegetables, cut fruits, and the like.

The amount of fruits and vegetables contained in the bag may vary depending on the size of the bag, the type of fruits and vegetables, and the like. For fruits and vegetables for general consumers, an example is 50 to 1000 g, preferably 100 to 800 g.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.
Hereinafter, an example of the reference embodiment of the present invention will be shown.
<1>
A fruit and vegetable freshness-preserving packaging container made of a resin film having holes.
The diameter of the hole is less than 1000 μm
A fruit and vegetable freshness-preserving packaging container in which the microcrystal size of the resin film determined by the X-ray diffraction method is 2.5 to 3.5 nm.
<2>
The fruit and vegetable freshness-preserving packaging container according to <1>.
A fruit and vegetable freshness-preserving packaging container in which the degree of orientation of the resin film determined by an X-ray diffraction method is 70 to 85%.
<3>
The fruit and vegetable freshness-preserving packaging container according to <1> or <2>.
The resin film is a fruit and vegetable freshness-preserving packaging container having the plurality of holes.
<4>
The fruit and vegetable freshness-preserving packaging container according to any one of <1> to <3>.
The holes are present on the outer surface of the fruit and vegetable freshness-preserving packaging container at a density of 1 to ^{1500 pieces / m 2.}
<5>
The fruit and vegetable freshness-preserving packaging container according to any one of <1> to <4>.
A fruit and vegetable freshness-preserving packaging container having a hole diameter of 30 to 500 μm.
<6>
The fruit and vegetable freshness-preserving packaging container according to any one of <1> to <5>.
The resin film contains an antifogging agent and contains
A fruit and vegetable freshness-preserving packaging container in which the water contact angle of the resin film on the inner surface side of the container is 3 to 60 °.
<7>
The fruit and vegetable freshness-preserving packaging container according to any one of <1> to <6>.
The resin film is a fruit and vegetable freshness-preserving packaging container containing at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene.
<8>
A package containing fruits and vegetables in which fruits and vegetables are packaged in the fruit and vegetable freshness-preserving packaging container according to any one of <1> to <7>.
<9>
A method for preserving the freshness of fruits and vegetables, wherein the fruits and vegetables are packaged using the fruit and vegetable freshness-preserving packaging container according to any one of <1> to <7>.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. As a reminder, the invention is not limited to examples.

<Preparation of resin film>
(Manufacturing of film 1)
A commercially available polypropylene resin was melted at 200 ° C., and an antifogging agent in which diglycerin laurate and decaglycerin laurate were mixed at a mass ratio of 98: 2 was added so as to have a concentration of 7% by mass. This was extruded from the die and subsequently stretched three times in the MD direction and three times in the TD direction over 10 seconds using a roll stretching machine. At this time, the roll temperature of the roll stretching machine was set to 90 ° C.
The film obtained by stretching was cooled by a roll set at 20 ° C. for 2 seconds, and then wound up by a roll at room temperature (particularly not temperature-controlled).

(Manufacturing of film 2)
A commercially available polypropylene resin was melted at 200 ° C., and an antifogging agent in which diglycerin laurate and decaglycerin laurate were mixed at a mass ratio of 98: 2 was added so as to have a concentration of 7% by mass. This was extruded from the die and subsequently stretched three times in the MD direction and three times in the TD direction over 10 seconds using a roll stretching machine. At this time, the roll temperature of the roll stretching machine was set to 80 ° C.
The film obtained by stretching was cooled by a roll set at 20 ° C. for 2 seconds, and then wound up by a roll at room temperature (particularly not temperature-controlled).

(Manufacturing of comparative film 1)
A commercially available polypropylene resin was melted at 200 ° C., and an antifogging agent in which diglycerin laurate and decaglycerin laurate were mixed at a mass ratio of 98: 2 was added so as to have a concentration of 7% by mass. This was extruded from the die and subsequently stretched three times in the MD direction and three times in the TD direction over 10 seconds using a roll stretching machine. At this time, the roll temperature of the roll stretching machine was set to 70 ° C.
The film obtained by stretching was cooled by a roll set at 20 ° C. for 2 seconds, and then wound up by a roll at room temperature (particularly not temperature-controlled).

(Manufacturing of comparative film 2)
A commercially available polypropylene resin was melted at 200 ° C., and an antifogging agent in which diglycerin laurate and decaglycerin laurate were mixed at a mass ratio of 98: 2 was added so as to have a concentration of 7% by mass. This was extruded from the die and subsequently stretched three times in the MD direction and three times in the TD direction over 20 seconds using a roll stretching machine. At this time, the roll temperature of the roll stretching machine was set to 100 ° C.
The film obtained by stretching was cooled by a roll set at 20 ° C. for 2 seconds, and then wound up by a roll at room temperature (particularly not temperature-controlled).

Each film was analyzed using an X-ray structure analyzer "NANO Viewer" manufactured by Rigaku Co., Ltd., and the obtained data was analyzed to determine the crystallite size and the degree of orientation.
The mathematical formulas for determining the crystallite size and the degree of orientation are as described above. The measurement surface was the (111) surface of polypropylene. The setting of the device, the preparation of the sample for measurement, and the direction in which the X-ray is incident are described below.
The details of the measurement conditions are as follows.
[Device settings]
・ Tube voltage, tube current: 40kV, 40mA
・ Tube: Cu
・ Beam size: 2 mm x 8 mm
・ Irradiation time: 10 min
・ Measurement mode: Extended measurement ・ Camera distance: 96.93 cm
[Sample for measurement]
-Measurement of microcrystal size: The film was cut into a size of 10 mm x 10 mm, and four films were stacked and fixed to the auto sample changer of the apparatus in the MD direction. X-rays were applied to this from the ND direction.
-Measurement of degree of orientation: The film was cut into a size of 2 mm x 10 mm, and eight films were stacked and fixed to the auto sample changer of the apparatus in the same MD direction. X-rays were applied to this from the TD direction.

In addition, the contact angle of each film with water is determined by the droplet method using DROPMASTER-50 manufactured by Kyowa Interface Science Co., Ltd., and the water contact angle 7 seconds after dropleting 2 μL of purified water on the surface to be measured. Obtained by measuring.

<Perforation>
A rotary support roll having 5 grooves having a width of 5 mm and a depth of 5 mm was prepared on a roll having a diameter of 318 mm and a width of 725 mm at intervals of 100 mm from a position 150 mm from both ends so as to have the shape shown in FIG.
As a laser irradiation device, a carbon dioxide laser having a maximum output of 150 watts was prepared.
Each of the five laser irradiation devices was installed so that the position of laser irradiation corresponds to the position of the groove of the rotary support roll. The laser irradiation device was installed so that the distance from the resin film was 10 to 15 mm. The focus of the laser was set to a position slightly outside the film from the surface of the resin film on the opposite side of the incident surface of the laser.

Next, by rotating the rotary support roll at a peripheral speed of 60 m / min using the devices shown in FIGS. 1 and 2, the film is run on the rotary support roll at a constant running speed, and each laser irradiation device is used. The pulsed laser was irradiated at regular intervals. ^{At this time, a nitrogen gas pressure of 1.0 kg / cm 2} (gauge pressure) was applied to the compressed gas introduction path, and nitrogen gas was blown from the tip of the nozzle along the laser beam during laser irradiation.

(Evaluation of whether the size of the hole is constant)
First, any five were selected from the perforated holes.
Next, each of the five holes was observed with an optical microscope, and the diameter of each hole (diameter equivalent to a circle) was determined.
Then, it was evaluated whether or not the size of the hole was constant by the value obtained by subtracting the minimum value from the maximum value among the obtained five diameter values. The smaller this value is, the easier it is to provide holes of substantially the same size / shape whenever the drilling conditions are constant.

In the table below, the average value of the circle-equivalent diameters of any five holes is described as the "hole diameter".

<Bag making>
First, two perforated resin films obtained by the above <perforation> were laminated.
Then, using an impulse sealer, heat-sealing was performed on three sides (both sides and bottom). As the impulse sealer, FI-400Y-10PK manufactured by Fuji Impulse Co., Ltd. was used. The heat-sealing process was performed under the conditions of 160 ° C. and a sealing time of 1 second to form a heat-sealing portion having a width of 10 mm.
From the above, a substantially rectangular packaging bag was obtained. The bag size (outer dimensions) of the obtained packaging bag was 200 mm × 300 mm.

(Heat seal strength (peeling strength))
The heat seal strength was measured as follows.
-Measurement environment: 23 ° C, 50% RH
-Sample preparation: Two sections having a width of 15 mm were cut out from each film and heat-sealed at 160 ° C. in parallel with the width direction to have a width of 5 mm.
-Measurement: Using a Tencilon universal tester RTC-1210 manufactured by Orientec, the grips were pulled at a speed of 300 mm / min in the 180 ° direction with a grip interval of 70 mm. Then, the maximum strength when the heat seal portion was peeled off was determined. The measurement was performed 3 times, and the average value of the 3 times was taken as the heat seal strength.

(Break resistance)
First, 100 cc of nitrogen gas was sealed in the containers (bags) of each Example and Comparative Example, and the openings were heat-sealed to prepare bags containing nitrogen gas. The conditions for heat sealing were the same for each bag.
After that, the evaluator pushed the inflated bag containing nitrogen gas by hand to evaluate whether it could be easily opened. As a reminder, the holes provided in the resin film by perforation are small enough that the holes are hardly an escape route for air when "hand-operated by the evaluator" here.
Ten bags containing nitrogen gas were prepared in each Example and Comparative Example, and were evaluated by 10 evaluators. If less than 2 people answered that the package was easily opened, it was evaluated as 〇 (good), and if there were 2 or more people, it was evaluated as × (bad).

(Easy to open the mouth of the heat seal part)
First, the opening of the container (bag) was heat-sealed and closed under the conditions of 160 ° C. and 1 second.
After the heat seal, 10 evaluators manually opened the part closed by the heat seal. When the number of people who answered that it was easy to open was 9 or more, it was evaluated as 〇 (good), and when it was less than 9, it was evaluated as × (bad).

(Openability when processed into a zipper bag)
In the above <manufacturing of fruit and vegetable freshness-preserving container>, (4) a step of attaching a male chuck tape and a female chuck tape by heat fusion near the portion corresponding to the opening in the final bag before bag making is performed. added. As a result, bags provided with chucks (zippers) were produced (20 bags in each example and comparative example).
Twenty evaluators opened the bag with the chuck (zipper) closed. And
・ Passed products that can be opened smoothly without any problems
・ When opening the bag, the attached zipper tape may have come off, or the opening may have lost its suppleness due to excessive heat fusion between the zipper tape and the bag, making it difficult to open. It was accepted as a product.
As a final evaluation, the case where the number of accepted products was 18 bags or more was evaluated as 〇 (good), and the case where the number of passed products was less than 18 bags was evaluated as × (defective).

(Evaluation of freshness retention)
200 g of fresh green soybeans was placed in a container of each Example and Comparative Example, and the opening of the container was heat-sealed to prepare a package containing fruits and vegetables. For later evaluation, 10 packages containing fruits and vegetables were prepared for each container of each Example and each Comparative Example.
Each package was stored at 20 ° C. for 3 days, and then the presence or absence of commercial value (whether there was no discoloration or no offensive odor) was evaluated by 10 panelists. Of the 10 panelists, when 8 or more were judged to have commercial value, it was evaluated as ○ (sufficient freshness retention), and when less than 8 people, it was evaluated as × (poor freshness retention).

The table below summarizes various information on resin films and containers, evaluation results, and so on.

As shown in Table 1, the fruit and vegetable freshness-preserving packaging containers of Examples 1 and 2 have good bag resistance, ease of opening the mouth of the heat-sealed portion, and easy opening when processed into a zipper bag. Met. That is, the fruit and vegetable freshness-preserving packaging containers of Examples 1 and 2 had practically excellent characteristics. It is considered that this is because the microcrystal size of the resin film obtained by the X-ray diffraction method is 2.5 to 3.5 nm, so that the strength of the heat-sealed / heat-sealed portion becomes an appropriate size. .. In other words, the "peel strength" shown in the table is "not too large, too small" because the microcrystal size of the resin film determined by the X-ray diffraction method is 2.5 to 3.5 nm. The value was "No", which is considered to have led to good performance.
In addition, the fruit and vegetable freshness-preserving packaging containers of Examples 1 and 2 showed good freshness-retaining properties. This result is considered to be related to the fact that the size / shape of the holes of the fruit and vegetable freshness-preserving packaging containers used in Examples 1 and 2 was almost constant.

In Comparative Example 1, since the microcrystal size was too small, it is considered that the resin "melted too much" at the time of heat sealing, and the ease of opening the mouth of the heat sealing portion became poor.
In Comparative Example 2, it is probable that the resin was not sufficiently melted during heat sealing or heat fusion because the crystallite size was too large, and heat sealing / heat fusion with sufficient strength could not be performed.

11 Unwinding roll 12 Resin film 13 Laser irradiation device 14 Rotational support roll 15 Roll 16 Guide roll 17 Floating roll 18 Compressed gas introduction path 19 Nozzle tip 20 Pulsed laser 21 Light guide path 23 Conical beam 24 Hole 25 groove

Claims (8)

A fruit and vegetable freshness-preserving packaging container made of a resin film having holes.
The diameter of the hole is less than 1000 μm
The microcrystal size of the resin film determined by the X-ray diffraction method is 2.8 to 3.0 nm, and the degree of orientation determined by the X-ray diffraction method is 70 to 85%.
The resin film is a fruit and vegetable freshness-preserving packaging container containing stretched polypropylene (excluding those with a breathable material covering the holes) . The fruit and vegetable freshness-preserving packaging container according to claim 1.
The resin film is a fruit and vegetable freshness-preserving packaging container having the plurality of holes. The fruit and vegetable freshness-preserving packaging container according to claim 1 or 2.
The holes are present on the outer surface of the fruit and vegetable freshness-preserving packaging container at a density of 1 to ^{1500 pieces / m 2.} The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 3.
A fruit and vegetable freshness-preserving packaging container having a hole diameter of 30 to 500 μm. The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 4.
The resin film contains an antifogging agent and contains
A fruit and vegetable freshness-preserving packaging container in which the water contact angle of the resin film on the inner surface side of the container is 3 to 60 °. The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 5.
The resin film is a fruit and vegetable freshness-preserving packaging container containing at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene. A package containing fruits and vegetables, in which fruits and vegetables are packaged in the fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 6. A method for preserving the freshness of fruits and vegetables, wherein the fruits and vegetables are packaged using the fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 6.

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