JP2021172362A - Greengrocery freshness-keeping packaging container, greengrocery-containing package, and greengrocery freshness-keeping method - Google Patents

Abstract

To provide a greengrocery freshness-keeping packaging container having practically good characteristics.SOLUTION: The greengrocery freshness-keeping packaging container comprises a resin film. The resin film has a hole of 1-10 mm in diameter, and has an air-permeable material attached thereto to cover the hole. The resin film contains at least one selected from the group consisting of oriented polypropylene and linear low-density polyethylene. The degree of orientation of the resin film obtained by the x-ray diffractometry is 70-85%.SELECTED DRAWING: Figure 1

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 packaging body 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 post-harvest storage, distribution or storage, the fruits and vegetables themselves consume energy and lose their freshness.
Therefore, studies have been conducted so far to suppress deterioration of freshness of fruits and vegetables by packaging fruits and vegetables using a packaging material having adjusted air permeability.

For example, Patent Document 1 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 and heat-bonding 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. It is characterized in that an adhesive layer is provided around the outer surface of the microporous film or the perforated film.
Patent Document 1 describes that it is easy to maintain the freshness of fruits and vegetables by packaging fruits and vegetables using such a packaging material whose gas permeability is controlled.

Japanese Unexamined Patent Publication No. 10-262548

As in Patent Document 1, it is conceivable to adjust the air permeability of the resin film by providing holes in the resin film and attaching a breathable material capable of controlling gas permeability to the holes. .. Further, it is conceivable to manufacture a fruit and vegetable freshness-preserving packaging container using the resin film whose breathability is adjusted in this way, and further, to wrap the fruit and vegetable using the fruit and vegetable freshness-preserving packaging container.

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.
The resin film is provided with holes having a diameter of 1 to 10 mm.
A breathable material is attached to the resin film so as to cover the holes.
The resin film comprises at least one selected from the group consisting of stretched polypropylene and linear low density polyethylene.
Provided is 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%.

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 the freshness of fruits and vegetables is provided, in which the fruits and vegetables are packaged using the above-mentioned packaging container for preserving the freshness of fruits and vegetables.

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

It is a figure which showed typically an example of the fruit and vegetable freshness preservation packaging container.

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".

<Packaging container for maintaining freshness of fruits and vegetables>
FIG. 1 is a diagram schematically showing an example of a fruit and vegetable freshness-preserving packaging container (hereinafter, also referred to as “container 1”) of the present embodiment.
The container 1 is made of a resin film 3.
The resin film 3 is provided with holes 5 having a diameter of 1 to 10 mm.
A breathable material 7 is attached to the resin film 3 so as to cover the holes 5. “To cover the hole 5” means that the entire hole 5 overlaps with the breathable material 7 when the periphery of the hole 5 and the breathable material 7 is viewed from the outer surface side of the container 1.
The resin film 3 contains at least one selected from the group consisting of stretched polypropylene and linear low density polyethylene.
The degree of orientation of the resin film 3 determined by the X-ray diffraction method is 70 to 85%, preferably 73 to 84%.

When the degree of orientation is determined by the X-ray diffraction method, X-rays are usually incident from the TD direction (Transverse Direction: horizontal axis direction) of the resin film 3.
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.

In general, the behavior of thermal melting and subsequent solidification of a polymer depends not only on the primary structure of the polymer, but also on the state of crystallization and orientation of the polymer.
By adopting the resin film 3 containing at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene and having an orientation degree of 70 to 85% determined by the X-ray diffraction method. It is presumed that the resin does not melt "moderately" and does not "melt too much" at the heat-sealing temperature and time normally used for packaging fruits and vegetables. Therefore, (i) sufficient heat-sealing property can be obtained, a chuck (zipper) can be attached with sufficient strength, and (ii) the heat-sealed portion can be easily peeled off with an appropriate force. Is presumed to be compatible.
As a reminder, the present invention is not limitedly interpreted by the above speculation.

In order to make the degree of orientation of the resin film 3 determined by the X-ray diffraction method 70 to 85%, it is preferable to form polypropylene and / or linear low-density polyethylene under appropriate conditions. Details of the material and film forming conditions will be explained later. Of course, the method of setting the degree of orientation to 70 to 85% 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 3.

A specific description of the container 1 will be continued.

(Resin film)
As the resin film 3, a resin film containing at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene and having an orientation degree of 70 to 85% determined by an X-ray diffraction method is appropriately used. be able to.
From the viewpoint of optimizing the degree of orientation, the resin film 3 is preferably stretched.
The resin film 3 may contain only one kind of resin, or may contain two or more kinds of resins.

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.

The resin film 3 may contain additives such as an anti-fog agent and an anti-condensation agent in addition to the resin. By including an appropriate additive in the resin film 3, it is possible to impart desirable properties to the resin film 3 for packaging and storage of fruits and vegetables.
Specific examples of the anti-fog 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 1 with water is preferably 3 to 60 °, more preferably 10 to 59 °, and further preferably 20 to 58 °.
The contact angle may be adjusted with an additive such as an anti-fog agent or an anti-condensation agent, or may be performed by applying some treatment to the surface of the resin film 3, or both of these may be performed. You may. In terms of convenience and certainty of effect, the resin film 3 preferably contains an anti-fog agent.

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 droplet method for 7 seconds. It can be obtained by measuring the subsequent water contact angle.

The thickness of the resin film 3 is preferably 15 to 50 μm, more preferably 20 to 45 μm. When the thickness of the resin film 3 is 15 μm or more, the strength of the container 1 can be easily increased. When the thickness of the resin film 3 is 50 μm or less, the flexibility (suppleness) of the container 1 can be maintained.

The method for obtaining the resin film 3 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 3 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, by forming a film of polypropylene and / or linear low-density polyethylene under the following procedures and conditions, it is easy to produce a resin film having an orientation degree of 70 to 85%. In short, a resin film having a degree of orientation of 70 to 85% can be produced by appropriately setting the temperature, magnification and time during stretching, and the temperature and time of subsequent cooling by the cooling roll.
(1) The raw material is melted at 200 to 230 ° C.
(2) The molten raw material is extruded from the die, and subsequently, it is stretched about 2 to 5 times in the MD direction and the TD direction for about 10 seconds using a roll stretching machine.
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, a commercially available resin film contains at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene, and the degree of orientation determined by the X-ray diffraction method is 70 to 70 to If there is a film that is 85%, it may be used as the resin film 3 to form a fruit and vegetable freshness-preserving packaging container.

(Hole)
The diameter of the hole 5 is 1 to 10 mm, more preferably 2 to 8 mm, as described above. By adjusting the diameter of the hole 5, it is easy to obtain appropriate air permeability according to the type of fruits and vegetables.
When the shape of the hole 5 cannot be regarded as substantially circular, the diameter of a perfect circle (diameter equivalent to a circle) having the same area as the opening area of the hole 5 can be used as the diameter of the hole 5.
(The shape of the hole 5 may be, for example, a rectangle. However, from the viewpoint of manufacturing suitability, the shape of the hole 5 is preferably substantially circular.)

The method of providing the holes 5 (drilling method) is not particularly limited. The hole 5 is typically a punched hole. That is, the holes 5 may be provided by using a punching device used in the field of packaging materials. The hole 5 may be provided by another method, for example, by pressing a hot needle having an appropriate thickness.

The ratio of the area of the holes 5 to the area of the outer surface of the container 1 is preferably 0.005 to 0.03%, more preferably 0.008 to 0.025%. By adjusting this ratio, it is possible to obtain more appropriate air permeability for maintaining the freshness of fruits and vegetables.

The resin film 3 may be provided with only one hole 5, or may be provided with a plurality of holes 5 (for example, 2 to 8).
When a plurality of holes 5 are provided in the resin film 3, it is preferable that all of the plurality of holes 5 are covered with the breathable material 7 from the viewpoint of adjusting the air permeability. Further, it is preferable that all the diameters of the plurality of holes 5 are 1 to 10 mm.

(Breathable material)
The breathable material 7 is usually present on the outer surface side of the container 1 (for reasons such as ease of manufacture). The breathable material 7 may be on the inner surface side of the container 1.

The breathable material 7 may be attached to the resin film 3 by, for example, an adhesive, but is preferably attached to the resin film 3 by thermal adhesion. By attaching the breathable material 7 to the resin film 3 by heat bonding, peeling of the breathable material 7 due to moisture or the like is suppressed, there is no need to use an additional material, and the adhesive "protrudes" when an adhesive is used. It is possible to obtain merits such as the problem of "" does not occur.
In addition, the resin film 3 contains at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene, and the degree of orientation of the resin film 3 determined by the X-ray diffraction method is 70 to 85%. This makes it possible to sufficiently increase the adhesive force between the resin film 3-breathable material 7 at the time of thermal adhesion. Then, it is possible to obtain the merit that the breathable material 7 is difficult to be detached when the container 1 is used. This advantage is particularly noticeable when the breathable material 7 contains polyethylene and / or polypropylene.

As a reminder, normally, the entire peripheral edge of the hole 5 in the resin film 3 is fixed to the breathable material 7. As a result, when the upper opening of the container 1 of FIG. 1 is closed, gas does not enter and exit without passing through the breathable material 7. Then, it becomes easier to obtain the effect of ventilation control by the breathable material 7.

The breathable material 7 can be any material having higher breathability than the resin film 3. From the viewpoint of availability and appropriate breathability, the breathable material 7 is preferably paper, woven fabric or non-woven fabric.

The paper, woven fabric or non-woven fabric that makes up the breathable material 7 is usually made of natural and / or synthetic fibers. Paper, woven fabrics or non-woven fabrics can contain one or more fibers.
Examples of natural fibers include fibers containing cellulose and keratin. Examples of the synthetic fiber include polyester, polyamide, polyolefin, polyurethane and the like. Of course, fibers other than these are not excluded.
The method for producing paper, woven fabric or non-woven fabric is not particularly limited. For example, as the non-woven fabric, a non-woven fabric obtained by a known manufacturing method such as a flash spinning method, a melt blow method, a spunbond method, or a spunlace method can be used. The weaving method of the woven fabric is not particularly limited.

From the viewpoint of further enhancing the adhesiveness between the resin film 3 and the breathable material 7 by heat sealing (making it difficult to remove the breathable material 7), the breathable material 7 preferably contains a thermoplastic resin. Specifically, the breathable material 7 preferably contains the same thermoplastic resin as the material of the resin film 3, that is, polyethylene and / or polypropylene.
When the breathable material 7 is paper, woven fabric or non-woven fabric, the breathable material 7 can include, for example, a fibrous thermoplastic resin. Specifically, some or all of the fibers constituting the paper, woven fabric or non-woven fabric can be a fibrous thermoplastic resin such as polyethylene or polypropylene. Alternatively, a thermoplastic resin such as polyethylene or polypropylene may be present in the "gap" of the fibers in the paper, woven fabric or non-woven fabric.

When the breathable material 7 has an appropriate void, it becomes easier to control the respiration of the packaged fruits and vegetables more appropriately, and as a result, deterioration of the freshness of the fruits and vegetables can be further suppressed.
As an index of the degree of voids in the breathable material 7, the filling rate measured by a three-dimensional measurement X-ray CT apparatus (hereinafter, also simply referred to as “filling rate”) can be mentioned. In the present embodiment, the filling rate of the breathable material 7 is preferably 35 to 80%, more preferably 45 to 75%, still more preferably 50 to 70%. When the filling rate is within an appropriate numerical range, it becomes easier to control the respiration of the packaged fruits and vegetables more appropriately, and as a result, deterioration of the freshness of the fruits and vegetables can be further suppressed.
The filling factor can be determined using an appropriate three-dimensional measurement X-ray CT apparatus and analysis software. Please refer to the examples for specific matters concerning how to obtain the filling rate.

The thickness of the breathable material 7 is preferably 70 to 400 μm, more preferably 90 to 350 μm, and even more preferably 100 to 300 μm. By adjusting the thickness of the breathable material 7, it is possible to obtain more appropriate breathability for maintaining the freshness of fruits and vegetables.

As the breathable material 7 available on the market, paper, woven cloth or non-woven fabric used for food filters (tea bags and the like) can be preferably mentioned. In particular, some food filters contain polyethylene, polypropylene, etc. and can be heat-bonded (heat-sealed). Therefore, by using a food filter that can be heat-bonded as the breathable material 7, the breathable material 7 can be easily attached to the resin film 3 by heat-bonding. Further, the filter for food is preferable from the viewpoint that the container 1 is used for "packaging of fruits and vegetables".

(Form, size, etc. of packaging container)
The form and size of the container 1 are not particularly limited as long as fruits and vegetables can be packaged. The shape of the container 1 is typically a bag shape, more specifically a quadrangular (rectangular, square, etc.) bag shape.
As an example, the size of the container 1 can be about 100 mm × 100 mm to 250 mm × 350 mm for packaging of fruits and vegetables for general consumers.

A means for closing the opening, for example, a chuck (zipper) or the like, may be provided in the vicinity of the upper opening of the container 1 shown in FIG. 1 (not shown in FIG. 1). On the other hand, the container 1 itself does not have to be provided with a means for closing the opening. In this case, for example, the opening may be closed with a heat seal, adhesive tape, rubber band, string, or the like.

The container 1 provided with the chuck (zipper) is manufactured by, for example, the following procedure.
(1) First, a male chuck tape and a female chuck tape are attached to the inside of each of the two facing resin films by heat fusion. The male and female chuck tapes are usually made of thermoplastic resin.
(2) After that, the four sides of the resin film are heat-sealed and / or fused to obtain a container 1 (bag) having 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 1, and a known technique may be appropriately applied.
In the present embodiment, the resin film 3 contains at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene, and the degree of orientation of the resin film 3 is 70 to 85%. As a result, when the male chuck tape or the female chuck tape is heat-sealed to the resin film 3, the resin film 3 is appropriately melted and / or the resin on the resin film 3 side and the resin on the chuck side are appropriately melted. It is presumed that they are entwined with each other. And perhaps for that reason, the male chuck tape or female chuck tape and the resin film 3 can be fused sufficiently strongly.

(Manufacturing method of container)
The manufacturing method of the container 1 is not particularly limited.
When the bag-shaped container 1 is manufactured, the bag-making method is not particularly limited. A known bag making method (method such as heat sealing or fusing) can be appropriately applied.
The hole 5 can be provided by a punching device or a hot needle, for example, as described above.
The breathable material 7 can be attached to the resin film 3 by, for example, a heat sealing method (heat adhesion) or a method using an adhesive, as described above.
The method for manufacturing the container 1 provided with the chuck (zipper) is as described above.

When the container 1 is in the shape of a bag, from the viewpoint of manufacturing efficiency, the manufacturing procedure of (1) perforation of a resin film, (2) attachment of a breathable material, (3) bag making, or (1) The manufacturing procedure of perforating a resin film, (2) making a bag, and (3) attaching a breathable material is preferable. Of course, the manufacturing procedure is not limited to this.

Arbitrary characters and patterns may be printed on the container 1. Printing may be performed 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.

<Packaging with fruits and vegetables, how to keep the freshness of fruits and vegetables>
By packaging (preferably sealing) fruits and vegetables in the fruit and vegetable freshness-preserving packaging container of the present embodiment (for example, the above-mentioned container 1), 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 (for example, the above-mentioned container 1), the freshness of the fruits and vegetables can be maintained (deterioration of the fruits and vegetables is suppressed).

As an example, first, a container 1 is prepared, and an appropriate amount of fruits and vegetables is stored in the internal space thereof. After that, the opening of the container 1 is heat-sealed (heat-sealed) to form a heat-sealed portion (seal width is typically about 10 mm). By the above 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 1 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 radish, spinach, komatsuna, mizuna, mibuna, asparagus, kushinsai, lettuce, thyme, sage, parsley, Italian parsley, rosemary, oregano, lemon balm, turnip, lavender, salad burnet, rams ear, rocket. , Dandy Lion, Nastatum, Basil, Arugula, Creson, Moroheiya, Celori, Kale, Negi, Cabbage, Hakusai, Shungiku, Saladana, Sanchu, Fuki, Nabana, Chingensai, Mitsuba, Seri, Mekabetsu, Broccoli, Califlower, Myoga, Daikon Carrots, gobos, radishes, turnips, sweet potatoes, potatoes, nagaimo, yams, sweet potatoes, ginenjo, yams, peppers, paprika, shishitou, cucumbers, eggplants, tomatoes, cherry tomatoes, pumpkins, bitter melons, okra, sweet corn, edamame, pods, Examples include yam, 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.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. As a reminder, the present invention is not limited to the 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 in a roll set at 20 ° C. for 2 seconds, and then wound up in 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 in a roll set at 20 ° C. for 2 seconds, and then wound up in 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 in a roll set at 20 ° C. for 2 seconds, and then wound up in 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 in a roll set at 20 ° C. for 2 seconds, and then wound up in 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 degree of orientation was determined by analyzing the obtained data.
The formula for obtaining the degree of orientation is 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]
The film was cut into a size of 2 mm × 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.

<Preparation of breathable material>
Polypropylene non-woven fabric manufactured by TRSCO, product number: 955-0559, grain size: 30 g / m ² , thickness: 0.25 mm, filling rate measured by a three-dimensional measurement X-ray CT device: 67%, composed of substantially only polypropylene fibers.

The filling rate of the breathable material was determined under the following conditions using a three-dimensional measurement X-ray CT apparatus "TDM1000H-II (2K)" manufactured by Yamato Scientific Co., Ltd.
-Irradiated X-ray: voltage 45 kV, current 75 μA
-Mode: High-precision 25 minutes-Measurement sample: Breathable material cut out to a size of 16 mm x 20 mm and folded multiple times to a thickness of about 1 mm for setting in a CT device.

The CT data obtained by the above measurement was analyzed by the function "volume sample analyzer" of the industrial CT software "VGStudio MAX (version 2.2)" of System Create Co., Ltd. Specifically, in the CT data drawn in grayscale on the screen with the "volume sample analyzer", the boundary (threshold) between the fiber part and the void part is set, and it is displayed as [%] between the cursors. The numerical value (the ratio of the pixels of the fiber portion to all the pixels of the CT data) was taken as the filling rate.
The setting of the boundary (threshold value) between the fiber portion and the void portion has some arbitrariness. Therefore, for the measurement data of 1, three evaluators independently set a boundary (threshold value) and obtained the filling rate. The filling rate "67%" of the breathable material used this time is the average value of the filling rates obtained by the three persons.

<Manufacturing of freshness-preserving containers for fruits and vegetables>
The fruit and vegetable freshness-preserving containers of each Example and each Comparative Example were produced by the following procedure.
(1) Preparation of film and breathable material Two prepared films were prepared by cutting them to the sizes shown in Table 1. In addition, a breathable material (circular shape, diameter 15 mm) was prepared for the number of holes to be drilled in (2) below.
(2) Perforation One of the two films prepared in (1) was perforated by using a punching device. The diameter of the holes was 4 mm and the number of holes was one.
(3) Attachment of breathable material A breathable material was attached to the hole of the film by heat sealing. Specifically, (i) first, a breathable material is placed on the holes of the film, and (ii) then, from the top of the breathable material, a circular shape according to the diameter of the holes and the size of the breathable material. The hot plate (120 ° C.) of the above was pressed against it. As a result, the entire peripheral edge of the hole in the resin film was fixed to the breathable material.
(4) Bag making Two films (one with holes and a breathable material and one without) were stacked so that the four corners were aligned. 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. As a result, a heat-sealed portion having a width of 10 mm was formed.
In bag making, the breathable material was placed on the outside of the bag.
A sufficient number of bags were manufactured for the following evaluations.

<Evaluation>
(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 Tensilon 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.

(Bag resistance)
First, 100 mL of nitrogen gas was filled 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.
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 attached zipper tape has come off, or the opening has 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).

(Difficulty in removing breathable material)
First, 200 g of edamame was put in a bag, and 20 bags of edamame were prepared by heat-sealing the opening and closing the edamame in each of Examples and Comparative Examples.
The prepared 20 bags were placed in a cardboard having a size of 400 mm × 250 mm × 300 mm, and the cardboard was closed. Then, it shook up and down for 5 minutes. The shaking method was set to 10 cm in the vertical direction and 1 second for one round trip.
After that, each bag was checked, and the one in which the breathable material was not peeled off was regarded as an OK product, and the one in which the breathable material was peeled off was regarded as an NG product. When the number of OK products was 18 bags or more, it was evaluated as 〇 (good), and when it was less than 18 bags, it was evaluated as × (defective).

The table below summarizes various information and evaluation results regarding films.

As shown in Table 1, of the fruit and vegetable freshness-preserving packaging containers of Examples 1 and 2, the rupture resistance, the ease of opening the mouth of the heat-sealed portion, the easy-opening property when processed into a zipper bag, and the breathable material. The difficulty of removal was good in each case. As the resin film, at least one selected from the group consisting of stretched polypropylene and linear low-density polyethylene was used, and the degree of orientation determined by the X-ray diffraction method was 70 to 85%. It is probable that this is because the strength of the heat-sealed / heat-sealed portion has become an appropriate size. In other words, the resin film is stretched polypropylene or linear low density polyethylene, and the degree of orientation is 70 to 85%, so that the "peeling strength" shown in the table is "not too large, The value was "not too small", which is considered to have led to good performance.

<Evaluation of freshness retention>
200 g of fresh green soybeans were placed in the fruit and vegetable freshness-preserving containers of Examples 1 and 2, respectively, and the openings were heat-sealed to seal them. This was stored for 5 days in an environment of 20 ° C. and 50% RH.
Ten evaluators evaluated whether or not the discoloration (yellowing), troque (floating of water, that is, exudation of water due to the progress of putrefaction) and odor of green soybeans after storage were at a level that could be sold as a commercial product. bottom.

In each evaluation, 6 or more out of 10 people evaluated that they were "at a level where they could be sold as products." That is, it was confirmed that the fruit and vegetable freshness-preserving container of each example had good performance as a "fruit and vegetable freshness-preserving" container. Presumably, the breathable material attached to the hole in the container properly controlled the respiration of the green soybeans, thereby suppressing the deterioration of the green soybeans.

1 Container (packaging container for freshness of fruits and vegetables)
3 Resin film 5 holes 7 Breathable material

According to the present invention
A fruit and vegetable freshness-preserving packaging container made of a resin film.
The resin film is provided with holes having a diameter of 1 to 10 mm.
A breathable material is attached to the resin film so as to cover the holes.
The resin film comprises a stretched polypropylene emissions,
A fruit and vegetable freshness-preserving packaging container is provided in which the degree of orientation of the resin film determined by the X-ray diffraction method is 74.9 to 83.3%.

According to the present invention
A fruit and vegetable freshness-preserving packaging container made of a resin film.
The resin film is provided with holes having a diameter of 1 to 10 mm.
A breathable material is attached to the resin film so as to cover the holes.
The resin film contains stretched polypropylene and contains.
Wherein the resin film, the degree of orientation as determined by X-ray diffractometry Ri from 74.9 to 83.3% der,
Wherein the breathable material, the filling rate to be measured by the three-dimensional measuring X-ray CT apparatus Ru 50% to 70% der, vegetables and fruits fresh-keeping packaging container is provided.

Claims (10)

A fruit and vegetable freshness-preserving packaging container made of a resin film.
The resin film is provided with holes having a diameter of 1 to 10 mm.
A breathable material is attached to the resin film so as to cover the holes.
The resin film comprises at least one selected from the group consisting of stretched polypropylene and linear low density polyethylene.
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%. The fruit and vegetable freshness-preserving packaging container according to claim 1.
The resin film contains an anti-fog agent and contains
A fruit and vegetable freshness-preserving packaging container in which the contact angle of the resin film with respect to water on the inner surface of the container is 3 to 60 °. The fruit and vegetable freshness-preserving packaging container according to claim 1 or 2.
The breathable material is a fruit and vegetable freshness-preserving packaging container attached to the resin film by heat adhesion. 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 in which the breathable material is paper, woven fabric or non-woven fabric. The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 4.
The breathable material is a fruit and vegetable freshness-preserving packaging container containing a thermoplastic resin. The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 5.
The breathable material is a fruit and vegetable freshness-preserving packaging container containing polyethylene and / or polypropylene. The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 6.
A fruit and vegetable freshness-preserving packaging container having a filling rate of 35 to 80% measured by a three-dimensional measurement X-ray CT apparatus for the breathable material. The fruit and vegetable freshness-preserving packaging container according to any one of claims 1 to 7.
A fruit and vegetable freshness-preserving packaging container in which the ratio of the area of the holes to the area of the outer surface of the container is 0.005 to 0.03%. 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 8. 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 8.

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