JP7422522B2 - packaging - Google Patents

Description

The present invention relates to a package used for transporting plants such as fruits.

In order to maintain the quality of harvested fruit and provide it to the market, it is necessary to protect the fruit from impacts during transportation. Strawberries, peaches, and other fruits with relatively soft skins may be damaged by friction with transportation containers during transportation, so special measures are required.

A problem during transportation is that when a transportation vehicle travels over minute irregularities on the road surface, vibrations with a relatively high frequency may be generated in the vehicle body. Similar vibrations are generated by the driving of the engine even when the transportation vehicle is stopped or transported by ship, and are also transmitted to the transportation container.

According to the transport container described in Patent Document 1, the above-mentioned vibration can be solved by supporting the inner container only by the legs and by arranging the legs of the inner container to be located outward from the plant storage part. , the natural frequency of the plant housing section that vibrates between the legs of the medium container is relatively low. As a result, according to the transportation container, even when high-frequency vibrations are transmitted from the bottom of the main body to the concave part of the plant storage part through the legs of the medium container, it is possible to suppress the resonance of the fruit and the resulting damage to the epidermis. can.

Japanese Patent Application Publication No. 2018-193073

By the way, in order to maintain the freshness of fruits, etc. stored in containers, it is important to ensure that the fruits, etc. in a sealed container are breathable, the atmosphere inside the container, and the environment during transportation by vehicle, ship, etc., and in warehouses. One example is the control of the surrounding atmosphere during storage. For example, it is known that under high temperature and high humidity conditions, fruits etc. are easily damaged and the incidence of mold growth increases significantly. In particular, the humidity inside a hermetically sealed container has a great effect on fruits and the like.

Furthermore, the influence of humidity and temperature on maintaining the freshness of fruits, etc. in a container cannot be ignored, in addition to the humidity inside the sealed container, the temperature and humidity inside vehicles, ships, etc., and warehouses in storage facilities cannot be ignored. For example, after fruits are harvested at the production area and placed in containers, they may be stored in vehicles and transported, or stored in warehouses for a certain period of time, and then delivered to their destination. It often goes through The humidity and temperature in and around the container vary depending on various factors such as the time of year (season) when the fruit is brought in, the region, and the storage location, but in general, the air conditioning of the place where the fruit is stored in the container and the storage location is controlled. It can be controlled by However, depending on the situation, it is assumed that the storage of fruits and the transportation and storage of containers after storage are performed in facilities without sufficient air conditioning or outdoors.

In order to solve these problems, it is an object of the present invention to provide a package that is capable of reducing damage to the epidermis of plants such as fruits, and that maintains the freshness of plants such as fruits. .

<1> A package used for transporting plants,
a container body having a body bottom and a body side wall extending upward from a periphery of the body bottom, and forming a storage space surrounded by the body side wall above the body bottom;
an inner container having a top plate disposed in the storage space with a space between the bottom of the main body and the bottom of the main body;
The top plate has a plant storage part and a supported part provided outward from the plant storage part,
The plant storage section is provided with a plurality of recesses that are recessed downward and accommodate plants,
The supported part is provided with a medium container leg part extending downward from the top plate,
a container (X) in which the medium container is supported from below only by the legs of the medium container;
It is in close contact with at least a portion of the container (X), sealing at least one of the storage space and the plant storage section, and has an oxygen permeation rate of 13,000 to 33,000 cc/atm/m ² /day. , and a heat-shrinkable film (Y) having a water vapor permeation rate of 40 to 80 g/m ² /day;
A packaging body with.
<2> The package according to <1>, wherein the heat-shrinkable film (Y) has a laminated structure.
<3> A pair of heat-sealing layers in which the heat-shrinkable film (Y) contains a resin containing 50% by mass or more of an ethylene-vinyl acetate copolymer having an MFR of 2.0 to 6.0 g/10 minutes; A three-layer film having an inner layer containing a mixed resin of 50 to 10% by mass of high-pressure low-density polyethylene and 50 to 90% by mass of linear low-density polyethylene, the three-layer film having a free shrinkage rate of 15 at 90°C. % or less and a free shrinkage rate at 140° C. of 70% or more, the inner layer has a gel fraction of 10 to 30% by mass, and the pair of heat seal layers each have a gel fraction of 20 to 40% by mass. The package according to <1> or <2>, which is a certain three-layer crosslinked film.
<4> A heat-shrinkable multilayer film in which the heat-shrinkable film (Y) has a heat-sealing layer and an inner layer, and the heat-sealing layer is laminated on the inner layer,
The heat-sealing layer contains an ethylene-α-olefin copolymer (A) containing ethylene and an α-olefin having 4 to 18 carbon atoms,
The inner layer contains 20 to 80% by mass of propylene-α-olefin copolymer (B) having a density of 0.880 to 0.910 g/cm ³ and a density of 0.850 to 0.900 g/cm ³ 80 to 20% by mass of a propylene-α-olefin copolymer (C) that is amorphous or has a melting peak temperature of less than 120°C,
The propylene-α-olefin copolymer (B) has the following properties (B1) to (B4), and the propylene-α-olefin copolymer (C) has the following properties (C1) to The package according to <1> or <2>, which satisfies (C2).
(B1) Melting peak temperature (Tmp) is 120-165°C
(B2) The difference between melting start temperature (Tms) and melting end temperature (Tme) is 30 to 70°C
(B3) The difference between the melting peak temperature (Tmp) and the melting end temperature (Tme) is 3 to 30°C
(B4) Heat of fusion is 20 to 50 J/g
(C1) Heat of fusion is 40 J/g or less (C2) TanΔ peak temperature determined by dynamic viscoelasticity measurement is -30°C to 0°C
<5> The package according to any one of <1> to <4>, wherein the plant is a fruit.
<6> The main body side wall portion of the container main body has a convex portion formed such that a part of the wall surface including the upper end portion swells from the inner circumferential side to the outer circumferential side of the container main body, and is symmetrical with the convex portion. The package according to any one of <1> to <5>, further comprising a recess provided at a position such that a part of the wall surface is recessed from the outer circumferential side to the inner circumferential side.

According to the present invention, it is possible to provide a package that is capable of reducing damage to the epidermis of plants such as fruits, and is excellent in maintaining the freshness of plants such as fruits.

It is a perspective view showing a package of a 1st embodiment. FIG. 3 is an exploded view showing the relationship between the container body and the inner container. It is a schematic diagram showing the cross section of the package of a 1st embodiment. It is an exploded view showing the composition of the package of a 2nd embodiment. It is a schematic diagram showing the cross section of package 10 of a 2nd embodiment. FIG. 3 is a diagram for explaining vibration absorption by a double-structured container. It is a perspective view which shows the modification of the container main body of 2nd Embodiment.

Embodiments will be described below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and redundant description will be omitted. Note that throughout this specification, "plants" include transportable foods such as flowers, plants, etc., as well as fruits and vegetables such as fruits and vegetables.

《Package》
The package of this embodiment is a package used for transporting plants, and includes:
A container body having a body bottom and a body side wall extending upward from a periphery of the body bottom, and forming a housing space surrounded by the body side wall above the body bottom, and the body bottom. and an inner container having a top plate arranged in the storage space with a space therebetween,
The top plate has a plant storage part and a supported part provided outward from the plant storage part,
The plant storage section is provided with a plurality of recesses that are recessed downward and accommodate plants,
The supported part is provided with a medium container leg part extending downward from the top plate,
The inner container is supported from below only by the legs of the inner container, a "container (X)";
It is in close contact with at least a portion of the container (X), sealing at least one of the storage space and the plant storage section, and has an oxygen permeation rate of 13,000 to 33,000 cc/atm/m ² /day. , and a heat-shrinkable film (Y) (hereinafter sometimes simply referred to as "film (Y)") having a water vapor permeation rate of 40 to 80 g/m ² /day.

According to the package of this embodiment, by including both the container (X) having a specific structure and the film (Y) having specific properties, it is possible to use the package in situations where vibrations are transmitted to the container, such as during transportation, for example. It is possible to achieve both the effect of reducing damage to the epidermis of plants such as fruits and the excellent ability to maintain the freshness of plants such as fruits at a high level.
For example, if the contents of a package are damaged during transportation, the damage may become an entry point for mold and fungi. When the epidermis of a fruit or other plant is damaged (similar to when a person is injured), the nutritional source is quickly depleted through respiration, and its shelf life is reduced. Therefore, even if an attempt is made to improve the freshness maintenance of the plants contained in the package by focusing only on respiration control and water evaporation (wilting) control, there is a limit to the upper limit of the effect depending on the situation.
On the other hand, according to the package of this embodiment, it is possible to effectively suppress or reduce damage to the epidermis of plants such as fruits during transportation using the container (X), and further control respiration and moisture transpiration. By using the film (Y), it is possible to maintain the freshness of the fruits and other plants contained in the container, compared to when the container (X) and the film (Y) are used alone. can.

<Container (X)>
The container (X) includes a container body and an inner container.
The container body has a body bottom and a body side wall extending upward from the periphery of the body bottom, and a storage space is formed above the body bottom surrounded by the body side wall.
The medium container has a top plate, is supported from below by medium container legs provided on the top plate, and is housed in the storage space of the container body. The medium container is designed so that there is a space between the top plate and the bottom of the container body. Moreover, the top plate has a plant storage part and a supported part. The plant storage section is provided with a plurality of recesses that are recessed downward (in a direction from the top plate toward the bottom of the container main body) and in which plants are accommodated. Furthermore, the supported portion is provided outward from the plant storage portion of the top plate, and the supported portion is provided with an intermediate container leg portion extending downward.

The medium container is supported from below only by the medium container legs, and the medium container legs are provided in a supported portion of the top plate that is located outward from the plant housing portion. For this reason, the medium container can be configured, for example, so that the top plate is supported by the upper ends of the medium container legs that are widely spaced apart. Thereby, the natural frequency of the plant accommodating part that vibrates between the legs of the medium container can be made relatively low. As a result, even if high-frequency vibrations are transmitted from the bottom of the main body to the concave portion of the plant storage portion through the legs of the medium container, it is possible to suppress resonance of the fruit and damage to the epidermis caused by it.

The shape of the inner container leg portion is not particularly limited, but may be formed over the entire periphery of the top plate, for example. According to this configuration, the entire periphery of the top plate can be supported by the inner container legs, so that excessive bending of the top plate downward (towards the bottom of the container body) can be suppressed. As a result, it is possible to prevent the concave portion containing plants such as fruits from coming into contact with the bottom of the main body, thereby preventing vibrations from being directly transmitted from the bottom of the main body to the concave portion.

Further, the inner container leg portion may be inclined so as to extend outward from the top plate from its upper end to its lower end. According to this configuration, when the medium container receives an external force, the legs of the medium container can be elastically deformed so as to fall inward. As a result, even if the bottom of the main body vibrates at a relatively high frequency, the elastic deformation of the legs of the inner container reduces the transmission of vibration, making it possible to suppress resonance in fruits and other plants and the resulting damage to the epidermis. .

Further, the inner container leg portion may have an inflection portion between the upper end and the lower end thereof, in which the normal direction of the outer surface changes. According to this configuration, when the inner container is subjected to an external force, the inner container leg portion can undergo elastic deformation starting from the bending portion. As a result, even if the bottom of the main body vibrates at a relatively high frequency, the elastic deformation of the legs of the inner container reduces the transmission of vibration, making it possible to suppress resonance in fruits and other plants and the resulting damage to the epidermis. .

However, if the bottom of the main body is flat, when the transport container is placed in a cardboard box or the like, there is a risk that the contact range between the bottom of the main body and the bottom of the cardboard box will not be constant. Specifically, if the bottom of the cardboard box is distorted, the bottom of the body contacts the bottom of the cardboard box only through a portion of the distortion. In this way, if the contact range between the bottom of the main unit and the bottom of the cardboard box is not constant, the transmission path of vibration from the cardboard box to the bottom of the main unit will be irregular, and resonance of plants such as fruits may not be suppressed appropriately. There is sex.

Therefore, the container main body may be provided with a plurality of downwardly projecting main body legs on the main body bottom. At this time, the plurality of main body legs may be spaced apart from each other. According to these configurations, even if the bottom of the cardboard box is distorted, the bottom of the main body can be deformed between the plurality of main body legs and easily follow the distortion. As a result, it is possible to bring the plurality of main body legs into stable contact with the bottom surface of the cardboard box, etc., and to make the contact range between the main body bottom part and the bottom surface of the cardboard box constant.

Further, as described in Japanese Patent Application No. 2018-219431, the container body is arranged at a symmetrical position of the side part, from the inner circumferential side to the outer circumferential side in a portion including at least the upper end of the wall surface forming the side part. It may include a convex portion formed to bulge out and a concave portion formed to be concave from the outer circumferential side to the inner circumferential side. Such a container body includes a convex portion formed on the side wall of the main body so that a part of the wall surface including the upper end bulges from the inner circumferential side to the outer circumferential side of the container body, and a convex portion that is symmetrical to the convex portion. It is possible to use a recess provided at a position such that a part of the wall surface is recessed from the outer circumferential side to the inner circumferential side.
By having such a concavo-convex portion, stacking becomes easy and convenience is increased, and when the packages are stacked, it is possible to maintain a state in which the air holes on the top surface are not blocked by the upper container body. As a result, it is possible to maintain the freshness of the contents without inhibiting the respiration of the plants contained therein.

The container body and the inner container preferably have different resonance regions from the viewpoint of lowering the natural frequency of the container (X). For example, by forming the container body and the inner container using different materials with different resonance regions (for example, sheet materials with different resonance regions), the resonance regions of the container main body and the inner container can be made different. Can be done.
Generally, the "vibration frequency" of a sheet material is expressed by the following equation.

When the mass m of the contents is fixed, the vibration frequency can be suppressed to a low level by reducing the material-specific spring constant k, which is the elastic modulus of the sheet material, and the sheet thickness. However, when an external force is applied in the natural vibration range of a material, there is a region where the material vibrates significantly even if the externally applied force is small. This region is called a "resonance region." In this embodiment, if a combination of a container main body and a medium container with different resonance regions is used as the container (X), the vibration intensities of each cancel each other out, making it possible to absorb vibrations during transportation in a wide frequency range. possible (vibration absorption effect of double-structured container). For example, as shown in FIGS. 6A and 6B, each material has a different vibration intensity and resonance region with respect to the vibration frequency. For this reason, for example, if both the container main body and the inner container are formed using only material 1 in FIG. may become large (for example, see the vibration intensity of material 1 at vibration frequency X in FIG. 6(B)). On the other hand, if the container body and the inner container are formed using Material 1 or Material 2, respectively, and these are combined to form a double-structured container, the vibration intensities of Materials 1 and 2 are superimposed, and Material 1 and Material 2 are Since the vibration intensities of the double-walled container cancel each other out, it is possible to suppress the occurrence of vibrations caused by external forces in a wide frequency range (for example, at the vibration frequency material 2 cancel each other out and the vibrations are absorbed).
For example, an example of a combination of a container main body and a medium container that have different resonance regions for each vibration frequency is a PET sheet (thickness: 0.25 mm, elastic modulus (Young's modulus): 3500 MPa) for the container main body, and a PP sheet for the medium container. (Thickness: 0.30 mm, elastic modulus (Young's modulus): 1500 MPa), a combination of a container main body and an inner container using materials having different Young's moduli can be mentioned. For example, if strawberries (total mass: 360 g, mass per piece: approximately 20 g) are used as the content (plant) in the combination of the container main body and the inner container, according to the configuration, the vibration frequency X = Since the Z-direction acceleration of the strawberries can be suppressed to 1 G or less in the range of 5 to 50 Hz, rotation and jumping of the strawberries can be suppressed. This is thought to be because the combination of the container body and the inner container, which have different resonance regions for vibration frequencies, cancel each other's vibration strengths, suppressing the occurrence of vibrations caused by external forces in a wide frequency range. .

Further, in the container (X), a sheet-like cushioning material may be interposed between the container main body and the inner container. In this case, the legs of the inner container may be supported by the bottom of the main body via a cushioning material. According to this configuration, it is possible to adjust the frequency of vibration transmitted from the container body to the middle container using the buffer material. By setting the resonant frequency of the buffer material to be lower than the resonant frequency of the inner container, it is possible to suppress resonance of plants such as fruits due to the vibration and damage to the epidermis caused by the resonance.

The cushioning material can be installed such that its edges are bent and the edges are located between the main body side wall and the inner container leg. According to this configuration, even if the medium container moves within the storage space during transportation of the transport container, the collision between the main body side wall portion and the medium container leg portion can be alleviated by the edge of the cushioning material. As a result, it becomes possible to reduce the impact applied to plants such as fruits and to suppress damage to the epidermis of plants such as fruits.
By the way, at the corners of the storage space, the edges of the bent cushioning materials may overlap each other. From the perspective of preventing unnecessary vibrations from being transmitted from the container body to the inner container, the legs of the inner container are fixed to the side wall of the main body via the edges of the overlapping cushioning material. It is preferable to prevent this from happening. In order to prevent the legs of the inner container from being fixed to the side wall of the main body through the edges of the overlapping cushioning materials, for example, the height of the edge of the cushioning material should be adjusted to the side wall of the main body. It can be reduced to 1/2 or less. According to this configuration, even if the bent edges of the cushioning material overlap at the corners of the storage space, the legs of the inner container can be fixed to the side wall of the main body via the edges of the cushioning material. can be easily prevented.

<Heat shrinkable film (Y)>
The package of this embodiment has a heat-shrinkable film (Y) that is in close contact with at least a portion of the container (X).
The film (Y) is a heat-shrinkable film, and seals at least one of the storage space and the plant storage part of the container (X). Thereby, the plants such as fruits accommodated in the container (X) can be packaged in the package.

(Aspects of packaging)
In the package of this embodiment, the container (X) is attached to the film (Y) so that the film (Y) is in close contact with at least a portion of the container (X) and seals at least one of the storage space and the plant storage section. packaged.
The manner in which the container (X) is wrapped with the film (Y) is not particularly limited, but the container body is wrapped in the film (Y) so that at least a portion of the container body and the film (Y) are in close contact with each other. Examples include a form in which the plant storage portion of the medium container is sealed so that at least a portion of the medium container and the film (Y) are in close contact with each other, and combinations thereof. Here, the mode of sealing the "plant storage section" includes a mode in which a recess provided in the plant storage section and containing plants such as fruits is sealed with a film (Y).

Furthermore, the form of the film (Y) is not limited as long as it seals at least one of the storage space and the plant storage part of the container (X); for example, the entire container (X) is wrapped with the film (Y). Alternatively, a part of the container (X) (for example, the opening of the storage space) may be covered with the film (Y).
An example of a mode in which the entire container (X) is wrapped with a film (Y) is a mode in which the entire container body is packaged with a film (Y).
Further, as a mode in which a part of the container (X) is covered with the film (Y), for example, the film (Y) is brought into close contact with the upper edge of the main body side wall of the container main body, and the opening of the storage space is covered with the film (Y). By covering the storage space with a film (Y) to seal the storage space, or by covering the surface of the plant storage part of the medium container with a film (Y) so that the surface of the plant storage part and the film (Y) are in close contact with each other. Examples include a mode in which a concave portion in which a plant such as a fruit is stored is sealed, and a mode in which a plant housing portion (particularly a concave portion) is sealed by covering the entire inner container with a film (Y).

In this embodiment, 1) even if the contents such as fruits are easily damaged, it can be packaged with as little damage as possible, 2) it can be adapted to various container shapes, and 3) other packaging formats can be used. (For example, when attaching a top seal or a lid to a molded product), high-speed packaging is possible, and 4) By providing openings such as windows and holes on the sides and bottom of the container (X), it can be packaged from all directions. From the viewpoint of being able to (evenly) control the respiration of the contents, it is preferable to wrap the entire container (X) with a film (Y).

The film (Y) is not particularly limited as long as it has heat shrinkability, and a film that heat shrinks at a desired temperature can be used.For example, the effect on the container (X) and plants during heat shrink treatment, In addition, from the viewpoint of heat resistance during transportation and storage, the heat shrinkage temperature is preferably 40 to 150°C, more preferably 60 to 150°C, and particularly preferably 70 to 130°C. Further, the heat shrinkage rate of the film (Y) is preferably such that the heat shrinkage rates in both MD (length direction of the film (Y)) and TD (width direction of the film (Y)) are 20% or more. It is more preferably 23% or more, and even more preferably 30% or more. If the heat shrinkage rate is less than 20% in at least one direction, it is impossible to package beautifully without gaps, especially in pillow shrink packaging or top seal packaging. The heat shrinkage rate can be determined by shrinking the laminated film for 1 minute at a temperature of 140° C. and then measuring the MD and TD heat shrinkage rates of the laminated film, respectively, in accordance with ASTM-D2732.

The film (Y) has an oxygen permeation rate of 13,000 to 33,000 cc/atm/m ² /day, and a water vapor permeation rate of 40 to 80 g/m ² /day.
If the oxygen permeation rate of the film (Y) is less than 13,000 cc/atm/m ² /day, the housed plants will be in an oxygen-deficient state, and the fermentation reaction will be dominant instead of the respiration reaction, resulting in a decrease in the freshness retention of the plants. do. Furthermore, if the oxygen permeation rate of the film (Y) exceeds 33,000 cc/atm/m ² /day, the consumption of plant nutrients and water evaporation due to respiration will be accelerated. The oxygen permeation rate is preferably 13,000 to 30,000 cc/atm/m ² /day, more preferably 15,000 to 30,000, and more preferably 15,000 to 28,000 cc/atm/m 2 /day from the viewpoint of freshness retention of plants. /atm/m ² /day is particularly preferred.
Furthermore, if the amount of water vapor permeation through the film (Y) is less than 40 g/m ² /day, the inside of the package is likely to become overhumidified or dew condensed, which may cause the growth of mold on plants. Furthermore, if the amount of water vapor permeation through the film (Y) exceeds 80 g/m ² /day, water evaporation from the plants will be rapid and cause wilting. The amount of water vapor permeation is preferably 45 to 75 g/m ² /day, more preferably 50 to 70 g/m ² /day, from the viewpoint of keeping the plants fresh.

The thickness of the film (Y) is preferably 3 to 30 μm, more preferably 5 to 30 μm, and still more preferably 5 to 25 μm from the viewpoint of the balance between oxygen permeation rate and water vapor permeation amount.

The material for the film (Y) is not particularly limited as long as it satisfies the above-mentioned characteristics when formed into a film and does not impair the effects of this embodiment, and known materials can be appropriately selected and used. Further, the film (Y) may be a single layer or a film having a laminated structure. Examples of the heat-shrinkable film (Y) having a laminate structure include a film having a laminate of three or more layers, including a pair of heat-sealing layers and an inner layer, with the inner layer sandwiched between the heat-sealing layers. It will be done.

When the film (Y) has a heat-sealing layer and an internal layer, the thickness ratio of the heat-sealing layer to all layers of the film (Y) is not particularly limited as long as it does not impair the properties, but it depends on the sealing strength of the film. From this point of view, it is preferably 5 to 50%, more preferably 10 to 40%.
The thickness ratio of the inner layer to the entire film (Y) layer is not particularly limited as long as the properties are not impaired, but from the viewpoint of flexibility of the film (Y), it is preferably 20 to 80%. More preferably, it is 25 to 80%.

Although not particularly limited, examples of the film (Y) having a laminated structure include the following films (Y1) and (Y2).

(Film (Y1))
The following film (Y1) can be used as the heat-shrinkable film (Y) having a laminated structure.
Specifically, the film (Y1) includes a pair of heat-sealing layers containing a resin containing 50% by mass or more of an ethylene-vinyl acetate copolymer with an MFR of 2.0 to 6.0 g/10 minutes, and a high-pressure low-temperature sealing layer. A three-layer film having an inner layer containing a mixed resin of 50 to 10% by mass of density polyethylene and 50 to 90% by mass of linear low-density polyethylene, wherein the 90°C free shrinkage rate of the three-layer film is 15% or less, and Three layers having a free shrinkage rate at 140° C. of 70% or more, the inner layer having a gel fraction of 10 to 30% by mass, and the pair of heat sealing layers each having a gel fraction of 20 to 40% by mass. It is a crosslinked film.

Film (Y1) can achieve the heat shrinkability, oxygen permeation rate, and water vapor permeation amount required for the above-mentioned film (Y), and has a high gel fraction because it has a crosslinked structure, and also has a high gel fraction on the film surface. Due to its excellent smoothness, the film has high transparency and excellent visibility of contents. Furthermore, since even a thin film has high strength, it is possible to produce a film with a high stretching ratio, so it has excellent heat shrinkability.

As mentioned above, the film (Y1) includes a pair of heat-sealing layers containing a resin containing 50% by mass or more of ethylene-vinyl acetate copolymer, 50 to 10% by mass of high-pressure low-density polyethylene, and linear low-density polyethylene. and an inner layer containing a mixed resin of 50 to 90% by mass.

- Heat seal layer of film (Y1) -
The "ethylene-vinyl acetate copolymer" contained in the heat-sealing layer is not particularly limited, but preferably has a vinyl acetate content of 5 to 20% by mass. When the vinyl acetate content is 20% by mass or less, extrusion moldability is excellent and there is little acetic acid odor. On the other hand, when the vinyl acetate content is 5% by mass or more, transparency is excellent. A more preferable vinyl acetate content is 10 to 17% by mass.
Furthermore, the MFR of the ethylene-vinyl acetate copolymer measured under the conditions of 190°C and 2.16 kgf is preferably 2.0 to 6.0 g/10 min, more preferably 2.2 to 3.0 g/10 min. It's 10 minutes. When the MFR is 6.0 g/10 minutes or less, the melt tension is not too low and the stretching stability is improved, and a film having excellent mechanical strength such as tear strength and puncture strength can be obtained. On the other hand, when the MFR is 2.0 g/10 minutes or more, the melt tension does not become too high, and problems such as the film being torn during high-strength stretching are less likely to occur.

The content of the ethylene-vinyl acetate copolymer in the heat seal layer is preferably 50% by mass or more, more preferably 70% by mass or more. When the content of the ethylene-vinyl acetate copolymer is 50% by mass or more, kneading with additives such as antifogging agents and antistatic agents in the extruder is improved, and the antifogging performance and antistatic properties of the stretched film are improved. Additional performance such as prevention performance can be further improved. In addition, to the extent that the effects of the present invention are not impaired, the heat seal layer may include low density polyethylene, linear low density polyethylene, ethylene-aliphatic unsaturated carboxylic acid ester copolymer, ionomer resin, low pressure processed high density polyethylene, Highly branched polyethylene polymer polymerized with a transition metal catalyst, crystalline 1,2-polybutadiene, and other resins such as petroleum resins such as hydrogenated polyterpene, and copolymers of propylene and ethylene or butene-1 are mixed. It may also be used as For example, the transparency, glossiness, and hot tack sealability of the film can be improved by incorporating 50% by mass or less of linear low-density polyethylene into the heat-sealing layer, or by incorporating 50% by mass or less of ultra-low-density polyethylene into the heat-sealing layer. It can be mixed in to lower the melt tension of the heat-sealing layer and improve the high-temperature stretching stability.

-Inner layer of film (Y1)-
The high-pressure low-density polyethylene used in the inner layer of the film (Y1) is a homopolymer with many long chain branches. The component ratio in the inner layer of the high-pressure low density polyethylene is 50 to 10% by mass. Compared to linear low-density polyethylene, high-pressure low-density polyethylene has the property of being relatively easily crosslinked by ionizing radiation and has high melt tension. Therefore, when the component ratio of the high-pressure low-density polyethylene is 50% by mass or less, the melt tension will not become too high, the film will be less likely to tear during stretching, and thickness unevenness will be less likely to occur during stretching. On the other hand, by having a component ratio of 10% by mass or more in the inner layer, it imparts the melt tension necessary for stretching to the film, improving stretching stability, and plays a role in preventing the drawdown phenomenon, reducing the film thickness. It can be made uniform.

The density of the high-pressure low-density polyethylene used in the inner layer is not particularly limited, but is preferably from 0.910 to 0.928 g/cm ³ . Here, "density" is a value measured at 23° C. according to JIS-K-7112. When the density is 0.928 g/cm ³ or less, stretching itself becomes easy and the transparency of the obtained film improves. On the other hand, when the density is 0.910 g/cm ³ or more, there is no reduction in film rigidity due to too soft resin, and there is no reduction in the sliding properties of the film due to lack of stiffness of the film, resulting in excellent suitability for packaging machines. A more preferable density is 0.912 to 0.926 g/cm ³ , even more preferably 0.914 to 0.926 g/cm ³ .

The MFR of the high-pressure low-density polyethylene used in the inner layer measured under the conditions of 190° C. and 2.16 kgf is not particularly limited, but is preferably 0.2 to 7 g/10 minutes. When the MFR is 7 g/10 minutes or less, it plays a role in preventing the drawdown phenomenon, can prevent thickness unevenness, and improves stretching stability by imparting an appropriate melt tension to the film. On the other hand, when the MFR is 0.2 g/10 minutes or more, the extrusion load during extrusion molding is reduced, and extrusion efficiency and productivity are improved. A more preferable MFR is 0.3 to 6 g/10 minutes, and even more preferably 0.4 to 5 g/10 minutes.

The component ratio of linear low density polyethylene in the inner layer is 50 to 90% by mass. When the component ratio in the inner layer is 50% by mass or more, practically sufficient strength properties such as tear strength and puncture strength can be imparted to the entire film. On the other hand, when the component ratio in the inner layer is 90% by mass or less, the role of high-pressure low-density polyethylene can be easily expressed, resulting in excellent stretching stability. More preferably 55 to 85% by weight, still more preferably 60 to 80% by weight.

The linear low density polyethylene used in the inner layer preferably has a density of 0.900 to 0.940 g/cm ³ . When the density is 0.940 g/cm ³ or less, stretching itself becomes easy, and the resulting film not only has improved transparency but also low-temperature shrinkability. On the other hand, when the density is 0.900 g/cm ³ or more, the stiffness and slipperiness necessary for packaging machine suitability can be imparted to the film. A more preferable density is 0.905 to 0.935 g/cm ³ , even more preferably 0.910 to 0.930 g/cm ³ . Further, it is preferable that the MFR measured under the conditions of 190° C. and 2.16 kgf is 0.2 to 7 g/10 minutes. When it is 7 g/10 minutes or less, the stretching stability is improved and a product with excellent mechanical strength such as tear strength and puncture strength can be obtained. On the other hand, when the MFR is 0.2 g/10 minutes or more, the extrusion power of extrusion molding is stabilized and the extrusion efficiency is improved. A more preferable MFR is 0.5 to 5 g/10 minutes, and even more preferably 0.6 to 4 g/10 minutes.

Here, "linear low density polyethylene" means a copolymer of ethylene and α-olefin. The α-olefin is at least one type selected from those having 3 to 18 carbon atoms, such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Pentene-1, 4-methyl-pentene-1, hexene-1, and octene-1 are preferred from the viewpoint of mechanical strength such as impact resistance and tear strength, and film formability by stretching. The component ratio of ethylene in the linear low density polyethylene is preferably 80 to 95% by mass, more preferably 90 to 95% by mass.
The above linear low density polyethylene may be a polymer (MSC) obtained using a conventional multi-site catalyst such as a Ziegler catalyst, or a polymer (MSC) obtained using a single-site catalyst such as a metallocene catalyst. SSC), and a mixture of both may be used, and it is desirable to use at least one of these.

The film (Y1) may also contain additives commonly used in plastic processing, such as antifogging agents, heat stabilizers, antiblocking agents, slip agents, and crosslinking regulators. For example, by using a crosslinking regulator to change the degree of crosslinking between each layer, properties such as heat sealability can be further improved.
The film (Y1) is preferably crosslinked from the viewpoint of heat shrinkage characteristics and heat resistance during sealing. For this reason, it is preferable that the film (Y1) is crosslinked by irradiation with ionizing radiation after coextruding the inner layer and the heat-sealing layer and solidifying them by rapid cooling. The absorbed dose during the irradiation is preferably 7.0 to 10 Mrad, more preferably 7.5 to 9.0 Mrad. After this, the original film (Y1) is guided to a stretching machine and heated to 130 to 160°C by a heating zone, and is stretched 4 to 7 times in the longitudinal direction and 4 to 7 times in the transverse direction, that is, area stretching. It is preferable to stretch at a magnification of 16 to 49 times. The free shrinkage rate of the film stretched under these conditions is 15% or less at 90°C and 70% or more at 140°C.

-Gel fraction-
The gel fraction of the film (Y1) is such that the inner layer has a gel fraction of 10 to 30% by mass, and each heat seal layer has a gel fraction of 20 to 40% by mass. The film (Y1) is preferably one in which the inner layer has a gel fraction of 16 to 23% by mass, and each heat seal layer has a gel fraction of 25 to 35% by mass. Here, the "gel fraction" is the ratio of the undissolved portion obtained by extracting a sample in boiling P-xylene for 12 hours and expressed by the following formula.
Gel fraction (mass%) = (sample mass after extraction / sample mass before extraction) × 100

Satisfying the above-mentioned requirements for the gel fraction of the inner layer and the heat-sealing layer is sufficient to produce the excellent heat shrinkage properties characteristic of a crosslinked film and the molecular orientation to fully exhibit the heat shrinkage properties. It is preferable in terms of ensuring stability in stretching film formation and mechanical properties such as heat resistance, tear strength, and rigidity. When the gel fraction of the inner layer is 10% by mass or more, it not only improves the stability of stretched film formation at high temperatures, but also plays a role in preventing the drawdown phenomenon and imparts molecular orientation necessary for a heat-shrinkable film. It also becomes easier. On the other hand, when ethylene-vinyl acetate is used as the heat-sealing layer, the crosslinking efficiency is high, so it naturally has a high gel fraction, but by setting the gel fraction to 20% by mass or more, excellent transparency and gloss can be achieved. It can be applied to the film. Further, when the gel fraction of the inner layer is 30% by mass or less, the melt tension of the film during stretching becomes appropriate with the resin composition, so that high-temperature stretching at an area stretching ratio of 16 to 49 times becomes easy. On the other hand, when the gel fraction of the heat-sealing layer is 40% by mass or less, not only is stretching easy, but also stable heat-sealability can be imparted to the film.

The film (Y1) is, for example, a "polyolefin crosslinked film", which is prepared by heating and kneading at least one thermoplastic resin selected from polyolefin resins such as ethylene polymers and propylene polymers, or After laminating and extruding the molten resin from an annular die, the unstretched tube-shaped original fabric was rapidly cooled and solidified, cross-linked with an electron beam, guided to a stretching machine, and TD ((width direction of film (Y))) It can be produced by stretching 3 to 10 times, or 3 to 10 times in the MD (length direction of the film (Y)). Further, the film (Y1) can be subjected to crosslinking treatment or corona treatment after stretching, depending on the purpose.

(Film (Y2))
Furthermore, the following film (Y2) may be used as the heat-shrinkable film (Y) having a laminated structure.
Specifically, the film (Y2) is a heat-shrinkable multilayer film having a heat-sealing layer and an inner layer, the heat-sealing layer being laminated on the inner layer,
The heat-sealing layer contains an ethylene-α-olefin copolymer (A) containing ethylene and an α-olefin having 4 to 18 carbon atoms,
The inner layer contains 20 to 80% by mass of propylene-α-olefin copolymer (B) having a density of 0.880 to 0.910 g/cm ³ and a density of 0.850 to 0.900 g/cm ³ 80 to 20% by mass of a propylene-α-olefin copolymer (C) that is amorphous or has a melting peak temperature of less than 120°C,
The propylene-α-olefin copolymer (B) has the following properties (B1) to (B4), and the propylene-α-olefin copolymer (C) has the following properties (C1) to (C2) is satisfied.

(B1) Melting peak temperature (Tmp) is 120-165°C
(B2) The difference between melting start temperature (Tms) and melting end temperature (Tme) is 30 to 70°C
(B3) The difference between the melting peak temperature (Tmp) and the melting end temperature (Tme) is 3 to 30°C
(B4) Heat of fusion is 20 to 50 J/g
(C1) Heat of fusion is 40 J/g or less (C2) TanΔ peak temperature determined by dynamic viscoelasticity measurement is -30°C to 0°C

Film (Y2) can achieve the heat shrinkability, oxygen permeation rate, and water vapor permeation amount required for the above-mentioned film (Y), and has excellent deformation recovery after packaging by stretching at low temperature. Even if the contents are easily damaged, they can be wrapped tightly without damaging the contents. Furthermore, since it has delayed recovery properties, even if the contents move and touch the film after packaging, wrinkles do not occur, and a clean packaging state can be maintained.

- Heat seal layer of film (Y2) -
The heat seal layer contains an ethylene-α-olefin copolymer (A). By having the heat-sealing layer, the film (Y2) has good packaging machine suitability, especially optical properties such as slipperiness, sealing strength, transparency after shrink wrapping, and gloss.

The ethylene-α-olefin copolymer (A) is preferably a random copolymer of ethylene and at least one monomer selected from α-olefins having 4 to 18 carbon atoms. Examples of the α-olefin include 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, and 1-dodecene.

The ethylene-α-olefin copolymer (A) may be polymerized using either a multi-site catalyst or a single-site catalyst, but when packaging contents that require transparency, single-site catalysts may be used. It is preferable to use one polymerized with a site-based catalyst. In this case, from the viewpoint of transparency, it is preferable to use one having a molecular weight distribution (Mw/Mn) measured by GPC of 3.5 or less.

The density of the ethylene-α-olefin copolymer (A) is preferably 0.890 to 0.930 g/cm ³ from the viewpoint of sealing properties and optical properties, more preferably 0.900 to 0.920 g / ^cm3 . When the density is 0.890 g/cm ³ or more, it is preferable because the film surface is less sticky and has good sliding properties with packaging machines, and when the density is 0.930 g/cm ³ or less, the optical properties of the film are This is preferred in terms of good characteristics.

The melt flow rate of the ethylene-α-olefin copolymer (A) is preferably 0.2 to 7.0 g/10 min. When the melt flow rate is 0.2 g/10 min or more, it is preferable in that film strength can be obtained, and when it is 7.0 g/10 min or less, it is preferable in that film formation stability in the stretching process can be obtained.

In the film (Y2), the heat-sealing layer may contain other resins than the ethylene-α-olefin copolymer (A) as long as the properties thereof are not impaired. Other resins include ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-methyl methacrylate copolymer resin, and ethylene-methacrylate copolymer resin. Copolymer resin, ionomer resin, high-pressure low-density polyethylene, high-density polyethylene, α-olefin copolymer with a crystallinity of 30% or less by X-ray method, which is different from the above-mentioned ethylene-α-olefin copolymer (A) Examples include soft resins made of polymers, modified resins such as those obtained by acid modification, polybutene resins, crystalline 1,2-polybutadiene, and amorphous polypropylene resins.

-Inner layer of film (Y2)-
In the film (Y2), the inner layer contains 20 to 80% by mass of propylene-α-olefin copolymer (B) having a density of 0.880 to 0.910 g/cm ³ and 20 to 80% by mass of a propylene-α-olefin copolymer (B) having a density of 0.850 to 0.85%. 900 g/cm ³ and 80 to 20% by mass of a propylene-α-olefin copolymer (C) that is amorphous or has a melting peak temperature of less than 120°C.

In the film (Y2), the propylene-α-olefin copolymer (B) is a random mixture of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 to 8 carbon atoms. Copolymers or block copolymers are preferred.
Examples of the α-olefin in the propylene-α-olefin copolymer (B) include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. Among these, ethylene or 1-butene is particularly preferred. The propylene-α-olefin copolymer (B) is a propylene/ethylene random copolymer or block copolymer containing 30% by mass or less, preferably 1 to 25% by mass of ethylene, and 20% by mass of 1-butene. Random copolymer or block copolymer of propylene/1-butene containing % by mass or less, or propylene/ethylene/1-butene containing 30% by mass or less of an ethylene component and 20% by mass or less of a 1-butene component. Suitable resins include random copolymers or block copolymers consisting of these three components.

The density of the propylene-α-olefin copolymer (B) is 0.880 to 0.910 g/cm ³ , preferably 0.890 to 0.905 g/cm ³ . When the density is 0.880 g/cm ³ or more, rigidity can be imparted to the film and the operability of the film in packaging machines can be improved, and when the density is 0.910 g/cm ³ or less, the deformation recovery of the film can be improved. can improve sex.

The melting peak temperature (Tmp: characteristic B1) of the propylene-α-olefin copolymer (B) is 120 to 165°C, preferably 120 to 155°C. When the melting peak temperature is 120°C or higher, heat resistance can be imparted, and when the melting peak temperature is 165°C or lower, stretching stability during film formation can be obtained.

The difference between the melting start temperature (Tms) and the melting end temperature (Tme) of the propylene-α-olefin copolymer (B) (hereinafter sometimes simply referred to as "ΔTmA": characteristic B2) is 30 to 70. ℃, preferably 35 to 65℃, more preferably 40 to 60℃. When ΔTmA is 30°C or higher, low-temperature shrinkability can be imparted to the film, and when ΔTmA is 70°C or lower, high shrinkability can be imparted to the film.

The difference between the melting peak temperature (Tmp) and the melting end temperature (Tme) of the propylene-α-olefin copolymer (B) (hereinafter sometimes simply referred to as "ΔTmB": characteristic B3) is 3 to 30 ℃, preferably 5 to 25℃. When ΔTmB is 3° C. or higher, it is possible to suppress the resin from falling off during sealing in the packaging process, and when ΔTmB is 30° C. or lower, film formation stability can be obtained.

The heat of fusion (ΔHm: characteristic B4) of the propylene-α-olefin copolymer (B) is 20 to 50 J/g, preferably 25 to 48 J/g. When ΔHm is 20 J/g or more, the heat resistance of the film can be improved, and when ΔHm is 50 J/g or less, the low-temperature shrinkability of the film can be improved, making it a film with excellent deformation recovery properties. can do.

The proportion of the propylene-α-olefin copolymer (B) as a component of the inner layer is 20 to 80% by mass, preferably 30 to 70% by mass, and more preferably 40 to 60% by mass. When the ratio is 20% by mass or more, film forming stability becomes good, and when the ratio is 80% by mass or less, flexibility of the film can be obtained.

The melt flow rate of the propylene-α-olefin copolymer (B) is not limited, but is preferably 0.1 to 10 g/10 min.

In the film (Y2), the propylene-α-olefin copolymer (C) is preferably a copolymer obtained from propylene and 20% by mass or less of ethylene or an α-olefin having 4 to 8 carbon atoms. The α-olefin in the propylene-α-olefin copolymer (C) which is amorphous or has a melting peak temperature of less than 120°C includes 1-butene, 1-pentene, 1-hexene, 1-octene, 4- Examples include methyl-1-pentene and 3-methyl-1-pentene, among which ethylene or 1-butene is preferred as the α-olefin.

In the film (Y2), the propylene-α-olefin copolymer (C) is amorphous, showing no melting peak, or has a melting peak temperature of less than 120°C. If the film is amorphous and does not exhibit a melting peak, flexibility is imparted to the film, and if the melting peak temperature is less than 120° C., low-temperature shrinkability is imparted.
The propylene-α-olefin copolymer (C) may be polymerized using a multisite catalyst, a single site catalyst, or any other catalyst.

The density of the propylene-α-olefin copolymer (C) is 0.850 to 0.900 g/cm ³ , preferably 0.855 to 0.895 g/cm ³ . If the density is 0.850 g/cm ³ or more, it gives the film elongation at break, which is preferable in terms of suitability for packaging machines, and if the density is 0.900 g/cm ³ or less, it gives the film rigidity. preferable.

The heat of fusion (characteristic C1) of the propylene-α-olefin copolymer (C) is 40 J/g or less, preferably 30 J/g or less, more preferably 25 J/g or less, and 20 J/g or less. It is more preferable that it is below G. When the heat of fusion is 40 J/g or less, it is preferable because low-temperature shrinkability can be imparted to the film and deformation recovery properties can be improved in the package after shrinkage.

The tanΔ peak temperature (characteristic C2) determined by dynamic viscoelasticity measurement of the propylene-α-olefin copolymer (C) is -30°C to 0°C, preferably -28 to -5°C. If the tanΔ peak temperature is -30 to 0°C, the shrinkage of the film will be inhibited at the contact surface between the film and the packaged product during shrinkage, even if the packaged product is frozen or refrigerated in the film packaging process. This is preferable in that it is less likely to be wrinkled and wrinkles are less likely to occur after heat shrinkage.

When the α-olefin contained in the propylene-α-olefin copolymer (C) is ethylene, its content is preferably 5 to 17% by mass, more preferably 7 to 16% by mass. When the ethylene content is 5% by mass or more, it is preferable because the film has good deformation recovery properties, and when the ethylene content is 17% by mass or less, it is preferable because it can impart rigidity to the film.

The proportion of the propylene-α-olefin copolymer (C) as a component of the inner layer is 20 to 80% by mass, preferably 30 to 70% by mass, and more preferably 40 to 60% by mass. When the ratio is 20% by mass or more, deformation recovery properties can be imparted to the film after heat shrinkage, and when the ratio is 80% by mass or less, the heat resistance of the film becomes good.

The melt flow rate of the propylene-α-olefin copolymer (C) is not limited, but is preferably 0.1 to 10 g/10 min.

In the film (Y2), the melting start temperature (Tms), the melting end temperature (Tme), the melting peak temperature (Tmp), and the heat of fusion (ΔHm) are defined by measurement using an index scanning calorimeter (DSC). can do. The sample amount is 5 to 10 mg, the measurement atmosphere is nitrogen atmosphere, and indium is used as the calorific value standard. As for the heating program, first, the sample was heated from 0°C to 200°C at a heating rate of 10°C/min (1st. melting behavior), left at 200°C for 1 minute, and then heated at a cooling rate of 10°C/min. The mixture was cooled from 200°C to 0°C and left at 0°C for 1 minute (1st. crystallization behavior). Thereafter, the temperature was raised from 0°C to 200°C at a heating rate of 10°C/min (2nd. Melting behavior). The melting peak temperature (Tmp) is determined from the above-mentioned 2nd. In the specific heat curve obtained from the melting behavior, this is the temperature that exhibits the maximum amount of endotherm. In addition, the heat of fusion (ΔHm) is calculated using the straight line obtained by directly extrapolating the specific heat curve of the completely molten state to the low temperature side as the baseline, and the temperature at which 5% of the heat of fusion is absorbed is the melting start temperature ( Tms), and the temperature at which 95% of the heat of fusion is absorbed is the melting end temperature (Tme).

In the film (Y2), other resins than the propylene-α-olefin copolymer (B) and the propylene-α-olefin copolymer (C) are blended in the inner layer within a range that does not impair the properties. Good too. Other resins include ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-methyl methacrylate copolymer resin, and ethylene-methacrylate copolymer resin. Copolymer resins, ionomer resins, high-pressure low-density polyethylene, high-density polyethylene, modified versions of these resins by acid modification, propylene homopolymers, polybutene resins, crystalline 1,2-polybutadiene, amorphous Examples include polypropylene resins.

(Heat-shrinkable multilayer film)
Film (Y2), which is a heat-shrinkable multilayer film, is a heat-shrinkable multilayer film that has both high shrinkability and good deformation recovery properties after shrink wrapping, and preferably has the following properties.
(I) The longitudinal and transverse heat shrinkage rates of the film at 120°C are both 45 to 80%.
(II) The maximum thermal shrinkage stress in at least one of the longitudinal and lateral directions of the film at 80 to 140° C. is 250 to 400 gf/mm ² .

In the film (Y2), the heat shrinkage rate of the heat-shrinkable multilayer film can be measured according to ASTM D-2732. The measurement temperature is 120°C assuming pillow shrink packaging. The heat shrinkage rate at 120°C is preferably 45 to 80% in both the vertical and horizontal directions of the film, more preferably 45 to 75%, in order to obtain a beautiful finish without leaving corners after shrink wrapping. be. When the heat shrinkage rate at 120° C. is 45% or more, it is preferable because a beautiful packaging finish with no leftover corners can be obtained. Further, it is preferable that the heat shrinkage rate at 120° C. is 80% or less because the film can be shrunk at a lower temperature.

In the film (Y2), the heat shrinkage stress of the heat shrinkable multilayer film can be measured according to ASTM D-2838. The measurement temperature is between 80 and 140°C, which is the temperature at which shrink wrapping is actually performed. Heat shrinkage stress at temperatures between 80 and 140°C is due to the fact that when a primary package with a specified film margin is heat-shrinked in a shrink tunnel, air is quickly removed through small holes made in advance using a needle or the like. It is necessary to obtain a tight packaging finish, and it is necessary that the maximum thermal shrinkage stress of the film in at least one of the vertical and horizontal directions at 80 to 140°C is 250 to 400 gf/mm ² , preferably, It is 270 to 380 gf/mm ² . If the shrinkage stress value between 80 and 140°C is 250 gf/mm ² or more, air will be easily removed from the small holes provided in advance when the film shrinks, and a tight feeling will be obtained in the package after the film shrinks. This is preferable in terms of improving deformation recovery properties, and if the shrinkage stress value between 80 and 140°C is 400 gf/mm ² or less, a tray made of expanded polystyrene or the like is used when removing air inside the film due to shrinkage stress. This is preferable in that deformation can be suppressed.

Additives may be added to the film (Y2) in order to impart good antifogging properties and slip properties. Examples of additives include fatty acid esters of polyhydric alcohols, polyoxyethylene alkyl ethers, and polyalkylene glycol fatty acid esters.
Examples of fatty acid esters of polyhydric alcohols include monofatty acid esters, difatty acid esters, trifatty acid esters, polyfatty acid esters of polyhydric alcohols, and monoglycerin esters of saturated or unsaturated fatty acids having 8 to 18 carbon atoms. , diglycerin ester, triglycerin ester, tetraglycerin ester, and sorbitan ester are preferred, and more preferably monoglycerin ester, diglycerin ester, triglycerin ester, and tetraglycerin ester of saturated or unsaturated fatty acids having 12 to 18 carbon atoms. , a sorbitan ester. Specifically, glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin dipalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin diolate, glycerin trio. rate, glycerin monolinoleate, sorbitan laurate, sorbitan myristate, sorbitan palmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan diolate, sorbitan triolate, sorbitan linoleate, diglycerin laurate, diglycerin myristate, diglycerin palmitate, diglycerin stearate, diglycerin oleate, diglycerin linoleate, triglycerin laurate, triglycerin oleate, triglycerin stearate, tetraglycerin laurate, tetraglycerin Examples include oleate and tetraglycerin stearate, but it is preferable to use a glycerin ester of lauric acid or oleic acid in combination with a diglycerin ester in order to achieve both antifogging properties and slipperiness.

The layers containing additives to impart good antifogging properties and slip properties to the film include a heat seal layer and/or an inner layer, and when an intermediate layer is present between the heat seal layer and the inner layer. is preferably added to the heat seal layer and the intermediate layer. Addition methods to the resin of each layer include not only diluting with resin containing a high concentration of additives (masterbatch), but also methods of heating the additives to a molten state and directly injecting them into the resin. can.
Other additives include polyhydric alcohol fatty acid esters, polyoxyethylene alkyl ethers, surfactants other than polyalkylene glycol fatty acid esters, antioxidants, antistatic agents, and adhesives such as low molecular weight petroleum resins. Liquid additives such as mineral oil and the like can also be added to each layer to the extent that they do not impair the antifogging properties and slipperiness.

The film (Y2) contains a heat-sealing layer made of an ethylene-α-olefin copolymer (A), a propylene-α-olefin copolymer (B) and a propylene-α-olefin copolymer, within a range that does not impair its properties. An intermediate layer may be used between the inner layer made of polymer (C). The intermediate layer (i) serves as a retaining layer for an antifogging agent to maintain antifogging properties, (ii) improves adhesion between the heat seal layer and the inner layer, and suppresses delamination, (iii) It is preferable to provide a recovery layer of the film in which the recovered resin is re-pelletized using an extruder, and from the reasons of (i), (ii), and (iii) above, it is preferable to provide it within a range that does not impair its original characteristics. , other resins and additives other than the copolymer used for the heat seal layer and the inner layer may be blended in an amount of 60% by mass or less.
The recovered resin is not particularly limited as long as it is a resin recovered when producing a film, but examples include resin obtained by melting the film of this embodiment again. Examples of the other resins include polybutene resins, ethylene-vinyl acetate copolymer resins, ethylene-ethyl acrylate copolymer resins, ethylene-acrylic acid copolymer resins, ethylene-methyl methacrylate copolymer resins, Examples include ethylene-methacrylic acid copolymer resin, ionomer resin, high-pressure low-density polyethylene, high-density polyethylene, and propylene homopolymer.
The thickness ratio of the intermediate layer to all layers of the heat-shrinkable multilayer film is not particularly limited as long as the properties are not impaired, but it is preferably 60% or less, more preferably 55%. It is preferable that the ratio of the intermediate layer is 60% or less because the stretching stability is good.

In the film (Y2), the arrangement of the heat seal layer and the inner layer is not particularly limited as long as the heat seal layer is laminated on the inner layer, but for example, the heat seal layer (hereinafter referred to as ) and an internal layer (hereinafter sometimes simply written as "C"): S/C, both surface layers are heat seal layers. In the case of three layers consisting of: S/C/S, in the case of a total of three layers with one intermediate layer (hereinafter simply referred to as "B"): S/B/C, S/C /B, when both surface layers are heat-sealing layers and a total of 4 layers with one intermediate layer: S/B/C/S, when a total of 4 layers with 2 intermediate layers: S/B /C/B, and S/B/C/B/S in the case of a total of five layers in which both surface layers are heat sealing layers and two intermediate layers are used. It is also possible to use a different intermediate layer (hereinafter simply referred to as "D") in combination with intermediate layer B, such as S/B/C/D, S/D/C/B, S /D/B/C, 4 layers consisting of S/B/D/C, consisting of S/D/B/C/S, S/B/C/D/S, S/B/D/C/S 5 layers, 6 layers consisting of S/B/D/C/B/S, 7 layers consisting of S/B/D/C/B/D/S, and 8 layers and more. can also be configured.
The layer arrangement in this embodiment is preferably composed of at least three layers such as S/B/C or S/C/S; It is preferable that an intermediate layer such as the above is laminated between the heat seal layer and the inner layer.

The heat-shrinkable multilayer film of the film (Y2) is, for example, a "polyolefin-based low-temperature heat-shrinkable film", and is made of at least one heat-shrinkable polyolefin resin selected from polyolefin resins such as ethylene polymers and propylene polymers. After heating, kneading or laminating the plastic resin and extruding the molten resin from an annular die, the unstretched tube-shaped original fabric is rapidly cooled and solidified and guided to a stretching machine so that the stretching start point is below the melting point of the resin. It can be produced by reheating and stretching 2 to 5 times in the MD (length direction of the film (Y)) and 2 to 5 times in the TD (width direction of the film (Y)). Further, the film (Y2) can be subjected to crosslinking treatment or corona treatment before or after stretching depending on the purpose.

Hereinafter, an example of the structure of the package of this embodiment will be explained using the drawings.

[First embodiment]
The configuration of the package 1 of the first embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing a package according to a first embodiment. FIG. 2 is an exploded view showing the relationship between the container body and the inner container. FIG. 3 is a schematic diagram showing a cross section of the package 1 of the first embodiment, and a part of the cross section is omitted. In this embodiment, a case will be described in which a fruit (strawberry) is used as the plant and the entire container (X) is wrapped with a film (Y).

As shown in FIG. 1, the package 1 includes a container body 2, a middle container 3, and a film 5, and the container body 2 and the middle container 3 are entirely covered with the film 5. The package 1 is a container that accommodates a plurality of strawberries and is used for transporting the strawberries. Moreover, after transportation, the package 1 can be displayed at a store with the strawberries contained therein.

The container body 2 is made of thermoplastic resin such as polyethylene terephthalate, polystyrene, polypropylene, or the like. As shown in FIG. 2, the container body 2 has a body bottom portion 21 and a body side wall portion 22. As shown in FIG. The main body bottom portion 21 is a substantially flat plate-shaped portion, and its outer shape is rectangular in plan view. The main body side wall portion 22 extends upward from the periphery of the main body bottom portion 21 . The main body side wall portion 22 is formed over the entire periphery of the main body bottom portion 21 and has a closed annular shape. The main body bottom part 21 and the main body side wall part 22 are integrally formed, and both have a uniform thickness of about 0.20 mm to 0.50 mm. The container body 2 is formed using a different material from that of the inner container 3 so that each resonance region is different.

The container body 2 forms a housing space 20. The housing space 20 is defined by a main body bottom 21 and a main body side wall 22, and is open at the top. Note that, as shown in FIG. 3, the container body 2 is provided with a body leg portion 25. The main body legs 25 are integrally formed with the main body bottom 21 and protrude downward from the main body bottom 21. One main body leg portion 25 is provided near each of the four corners of the main body bottom portion 21.

As shown in FIGS. 1 to 3, the inner container 3 is made of thermoplastic resin such as polyethylene terephthalate, polystyrene, polypropylene, or the like. The thickness of the middle container 3 is approximately 0.1 mm to 0.5 mm, and it is flexible. As shown in FIG. 2, the middle container 3 has a top plate 31. The top plate 31 is a substantially flat plate-shaped portion, and its outer shape is a rectangle that is slightly smaller than the bottom 21 of the container body 2 when viewed from above. Further, the top plate 31 includes a plant storage section 311 and a supported section 312.

The plant storage portion 311 is a portion of the top plate 31 that is closer to the inside. The plant storage section 311 is provided with a recess 32 recessed downward from the top plate 31. The recesses 32 are arranged in a straight line, four in the short side direction and five in the long side direction, at intervals from each other. For example, in the case of a package 1 having a short side dimension of 150 mm and a long side dimension of 210 mm, the number of recesses 32 is preferably 3 to 20.

As shown in FIG. 3, the recess 32 has a recess bottom surface 32a, an upright side surface 32b, and an inclined side surface 32c. The recess bottom surface 32a is a curved surface that projects downward. The upright side surface 32b is a surface whose lower end is connected to the recess bottom surface 32a, extends toward the top plate 31, and whose upper end is connected to the top plate 31. The inclined side surface 32c is a surface whose lower end is connected to the recess bottom surface 32a, extends toward the top plate 31 at a gentler angle than the upright side surface 32b, and whose upper end is connected to the top plate 31.

The supported portion 312 is a portion of the top plate 31 that is located outside the plant storage portion 311 . The supported portion 312 surrounds the plant storage portion 311 and is provided over the entire periphery of the top plate 31 .

The supported portion 312 is provided with an inner container leg portion 34 extending downward from the top plate 31. The inner container legs 34 and the top plate 31 are integrally formed. The inner container leg portion 34 is inclined so as to extend outward from the top plate 31 from the upper end 34a side connected to the top plate 31 to the lower end 34b side.

Further, the medium container leg portion 34 has two bending portions 34c between the upper end 34a and the lower end 34b. The normal direction of the outer surface of the inflection portion 34c is different from the normal direction of other parts of the outer surface. The bending portion 34c is formed to extend linearly along each of the short side and long side of the top plate 31, so that the inner container leg portion 34 has a stepped shape.

The medium container 3 formed in this manner is placed in the accommodation space 20 of the container body 2. The inner container 3 is supported by contacting the upper surface of the main body bottom 21 only with the lower ends 34b of the inner container legs 34 without being restrained with respect to the container main body 2. By not restraining the middle container 3 with respect to the container main body 2, transmission of vibrations from the container main body 2 to the middle container 3 can be reduced.
Although not shown in FIG. 2, as shown in FIG. 3, between the main body bottom 21 and the inner container legs 34, there is an air packing 4 with its edges bent. is set up.

The air packing 4 is made of a resin material such as polyethylene or polypropylene, and has a sheet shape as a whole. As the air packing 4, a sheet-like one that has a rectangular shape when viewed from the front and whose outer shape is larger than the main body bottom 21 of the container main body 2 can be used. Further, the air packing 4 has a plurality of air bubbles, and the air bubbles 42 are formed on one side of the sheet 41 at intervals. Further, each bubble portion 42 contains air.

Further, as shown in FIG. 3, a gap is formed between the main body side wall part 22 of the container main body 2 and the inner container leg part 34b. The dimension of the gap is preferably about 0.1 mm to 5 mm. With such dimensions, it is possible to reduce the movement of the middle container 3 within the storage space 20 during transportation, while achieving a vibration absorption effect due to the double container structure.As a result, the movement of the middle container 3 can be reduced It is possible to suppress the impact on the strawberries S caused by this.

By disposing the middle container 3 in the storage space 20, the top plate 31 is disposed at a distance from the main body bottom 21. Further, a gap of about 3 mm is formed between the bottom surface 32a of the recess 32 and the top surface of the main body bottom 21 via the air packing 4.

As shown in FIG. 3, the strawberries S contained in the package 1 are stored in the recess 32 of the medium container 3. When the strawberry S is accommodated in the recess 32, its lower surface is supported by contacting the recess bottom surface 32a, and its side surfaces are covered by contacting the upright side surface 32b and the inclined side surface 32c. That is, the recess 32 has a shape that follows the outer shape of the strawberry S so that the strawberry S to be accommodated can be stably held. The inner container 3 is given a predetermined rigidity so that even when the strawberries S are stored in the recess 32, the recess bottom 32a does not come into contact with the upper surface of the main body bottom 21.

The container body 2 and the inner container 3 are covered with a film 5 with the strawberries S accommodated in the recesses 32. As shown in FIG. 3, the film 5 covers the entire container body 2 and is in close contact with the entire outer surface of the container body 2. Thereby, the accommodation space 20 is sealed by the film 5.

Further, as shown in FIG. 3, in the medium container 3, the height of the medium container legs 34 is set such that the height of the top plate 31 is lower than the upper end 221 of the main body side wall 22 of the container main body 2. Ru. For example, after the container body 2 is covered with the film 5, the heights of the main body side wall portion 22 and the inner container leg portion 34 are set so that a sufficient gap is secured between the film 5 and the top plate 31.

Further, as the film 5, the film (Y) is used as described above. For example, from the viewpoint of visibility and cosmetics, it is preferable that the film 5 is transparent. If the film 5 is transparent, even if the strawberries S are displayed at a store while being housed in the package 1, the consumer can visually check the state of the strawberries S through the lid member.

After housing the strawberries S, the package 1 covers the entire container body 2 with a film 5, and then heats it under reduced pressure to cause the film 5 to shrink. Thereby, the film 5 can be brought into close contact with the entire outer surface of the container body 2.

The operation of this embodiment will be explained.
As mentioned above, the inner container 3 is supported by contacting the main body bottom 21 only with the inner container legs 34. The medium container leg portion 34 is provided in a supported portion 312 of the top plate 31 located further outward than the plant storage portion 311 . Therefore, according to this configuration, the top plate 31 is supported by the upper end 34a of the middle container leg part 34 which is widely spaced apart.

When the package 1 is not receiving any external force, such as when not being transported, the top plate 31 bends slightly downward due to the weight of the strawberries S accommodated in the recess 32, but the top plate 31 is generally parallel to the bottom part 21 of the main body. state.

On the other hand, when the package 1 is subjected to external force during transportation or the like, vibrations may occur in the top plate 31. At this time, the top plate 31 deforms in a mode using the upper end 34a of the medium container leg portion 34 as a fulcrum.

In this way, the top plate 31 deforms using the upper end 34a of the inner container leg portion 34, which is widely spaced apart, as a fulcrum, so its natural frequency becomes relatively low. As a result, even when vibrations with a relatively high frequency are transmitted from the main body bottom 21 to the recess 32 of the plant storage section 311 via the medium container legs 34, the resonance of the strawberry S and the resulting damage to the epidermis can be suppressed. becomes possible.

The inner container leg portion 34 is formed over the entire periphery of the top plate 31.

According to this configuration, by supporting the entire periphery of the top plate 31 by the inner container legs 34, excessive downward deflection of the top plate 31 can be suppressed. As a result, it is possible to prevent the concave portion 32 containing the strawberries S from coming into contact with the main body bottom 21 and thereby to prevent vibrations from being directly transmitted from the main body bottom 21 to the concave portion 32.

The middle container leg portion 34 is inclined so as to extend outward from the top plate 31 from the upper end 34a side to the lower end 34b side.

According to this configuration, when the middle container 3 receives an external force, it becomes possible to elastically deform the middle container legs 34 so as to fall inward. As a result, even if the main body bottom 21 vibrates at a relatively high frequency, the elastic deformation of the inner container legs 34 reduces the transmission of vibration, making it possible to suppress the resonance of the strawberries S and the resulting damage to the epidermis. Become.

The inner container leg portion 34 has an inflection portion 34c between its upper end 34a and lower end 34b, in which the normal direction of the outer surface changes.

According to this configuration, when the inner container 3 receives external force, the inner container leg portion 34 can undergo elastic deformation starting from the bending portion 34c. As a result, even if the main body bottom 21 vibrates at a relatively high frequency, the elastic deformation of the inner container legs 34 reduces the transmission of vibration, making it possible to suppress the resonance of the strawberries S and the resulting damage to the epidermis. Become.

The height of the top plate 31 of the medium container 3 is set to be lower than the upper end 221 of the main body side wall portion 22.

According to this configuration, when the container main body 2 is covered with the film 5, it is possible to prevent the top plate 31 and the film 5 from coming into contact with each other, thereby preventing the inner container 3 from being restrained by the film 5. Thereby, direct transmission of vibrations from the main body bottom 21 to the recess 32 via the film 5 can be suppressed.

The package 1 includes an air packing 4, which is a sheet-like cushioning material, between the container body 2 and the inner container 3. The inner container leg portion 34 is supported by the main body bottom portion 21 via the air packing 4.

According to this configuration, the frequency of vibration transmitted from the container body 2 to the middle container 3 can be adjusted by the air packing 4. By setting the resonant frequency of the air packing 4 to be lower than the resonant frequency of the inner container 3, it becomes possible to suppress resonance of the strawberry S due to the vibration and damage to the epidermis caused by the resonance.

[Second embodiment]
Next, the configuration of the package 10 of the second embodiment will be described with reference to the drawings. FIG. 4 is an exploded view showing the configuration of the package of the second embodiment. FIG. 5 is a schematic diagram showing a cross section of the package 10 of the second embodiment, and a part of the cross section is omitted. The second embodiment is a modification of the first embodiment in terms of packaging using the film (Y). In this embodiment, a mode will be described in which a fruit (strawberry) is used as the plant and the inner container of the container (X) is wrapped with a film (Y). Note that the same members as those in the first embodiment are given the same numbers and the description thereof will be omitted.

As shown in FIG. 4, the package 10 is a container that accommodates a plurality of strawberries and is used for transporting them, as in the first embodiment. The package 10 is composed of a container body 2, an inner container 3, and a film 50. The film 50 has a rectangular shape when viewed from the front, and a sheet-like film having an outer shape larger than the plant storage section 31 of the medium container 3 can be used.

Further, as shown in FIG. 5, the inner container 3 is covered with a film 50 so as to be in close contact with the surface of the plant storage section 311 of the top plate 31, with the strawberries S stored in the recess 32. As a result, each recess 32 is sealed with the film 50. As the film 50, the above-mentioned film (Y) is used. For example, from the viewpoint of visibility and cosmetics, it is preferable that the film 50 be transparent. If the film 50 is transparent, the consumer can visually check the state of the strawberries S through the lid member even when the strawberries S are housed in the package 10 or displayed at a store.

In this embodiment, since the middle container 3 itself is covered with the film 50, the middle container 3 is not restrained with respect to the container main body 2, and only the lower end 34b of the middle container leg 34 is used to cover the main body bottom 21. It is supported by contacting the top surface. In this way, by not restraining the middle container 3 with respect to the container main body 2, transmission of vibrations from the container main body 2 to the middle container 3 can be reduced.
In addition, in this embodiment, since the middle container 3 itself is covered with the film 50, the middle container 3 is not restrained with respect to the container main body 2 due to the relationship with the film 50. Therefore, it is not necessary to design the height of the top plate 31 of the medium container 3 to be lower than the upper end of the main body side wall part 22 of the container main body 2, and the height relationship between the top plate 31 and the upper end of the main body side wall part 22 is It can be changed as desired. For example, as shown in FIG. 5, when the container main body 2 itself is not covered with the film 50, the height of the top plate 31 may be made higher than the upper end of the main body side wall portion 22.

The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, designs made by those skilled in the art as appropriate to these specific examples are also included within the scope of the present invention as long as they have the characteristics of the present invention. The elements included in each of the specific examples described above, their arrangement, materials, conditions, shapes, sizes, etc. are not limited to those illustrated, and can be changed as appropriate.

In the first embodiment described above, the bending portion 34c is formed to extend linearly along each of the short side and long side of the top plate 31. However, the invention is not limited to this embodiment. The bending portion may extend in a meandering curved line between the upper end 34a and the lower end 34b of the inner container leg portion 34.

In the first embodiment described above, the air packing 4 is used as a cushioning material. However, the invention is not limited to this embodiment. Various materials can be used as the cushioning material, such as a sponge made of a resin material, a cushion, or a nonwoven fabric.

Further, in the second embodiment, the container body 2 itself is not covered with the film 50. However, the invention is not limited to this embodiment. For example, a lid member (not shown) may be installed at the opening of the accommodation space 20 of the container body 2, the opening of the accommodation space 20 of the container body 2 may be covered with another film, or the entire container body 2 may be covered with another film. It may be covered with another film. In such a case, as in the first embodiment, the height of the top plate 31 is adjusted to the side wall portion 22 of the main body so that the inner container 3 is not restricted to the container main body 2 by the lid member or other film. It is preferable that it is lower than the upper end of .

Furthermore, when closing the opening of the accommodation space 20 of the container body 2 using a lid member or other film, it is preferable that air permeability and water vapor permeability within the accommodation space 20 be ensured. Therefore, when closing the opening of the accommodation space 20 of the container body 2 using a lid member or other film, the oxygen permeation rate and water vapor permeation amount of the lid member or other film are determined by the film (Y). Thus, it is preferable that the oxygen permeation rate is 13,000 to 33,000 cc/atm/m ² /day and the water vapor permeation amount is 40 to 60 g/m ² /day.

(Modified example)
Further, in the second embodiment, a container body 100 shown in FIG. 7 may be used instead of the container body 2. FIG. 7 is a perspective view showing a modification of the container main body of the second embodiment. As shown in FIG. 7, the main body side wall portion 22 of the container main body 100 is provided with a protrusion 60 and a recess 70 provided at a position symmetrical to the protrusion 60.

In the container body 100, the body side walls 22 are formed to rise slightly outward in a substantially perpendicular direction with respect to the body bottom 21.
The convex portion 60 is formed such that a portion of the wall surface including the upper end of the main body side wall portion 22 bulges from the inner circumferential side to the outer circumferential side of the container main body 100. The convex portion 60 protrudes in a substantially trapezoidal shape toward the outer circumferential side of the container body 100 in plan view when observed from above. Mounting surfaces 80A are provided on both sides of the recess 60 at the upper end of the wall surface of the main body side wall 22 on the recess 60 side.
The recessed portion 70 is formed such that a portion of the wall surface of the main body side wall portion 22 is recessed from the outer circumferential side to the inner circumferential side. The recess 70 protrudes in a substantially trapezoidal shape toward the inner peripheral side of the container body 100 in plan view when observed from above. A mounting surface 80B is provided on the upper end side of the recess 70.

In this modification, the concave portion 70 is provided at a position symmetrical to the convex portion 60. In FIG. 7, a convex portion 60 is provided on one side of the opposing main body side wall portions 22, and a recessed portion 70 is provided on the other side so as to be symmetrical about the substantially center of the surface direction of the main body bottom portion 21 as an axis. Therefore, when stacking two or more container bodies 100, if the convex portions 60 and the concave portions 70 are stacked in the same direction, the upper container body will fit completely into the storage space of the lower container body. overlap. On the other hand, when the protrusion 60 and the recess 70 are stacked in different directions, the bottom surface of the protrusion 60 and the bottom surface of the main body side wall 22 on the recess 70 side are placed on the mounting surface 80B and It is placed on the placement surface 80A. Therefore, the packages 10 can be easily stacked, increasing convenience, and when the packages 10 are stacked, the top of the film 50 can be kept unobstructed by the bottom of the container body 100. As a result, it is possible to maintain the freshness of the contents without inhibiting the respiration of the plants contained therein. In addition, in this modification, the convex part 60 and the concave part 70 are each provided in the opposing main body side wall part 22 as an example in which each part is provided in a symmetrical position, but this embodiment is not limited to this. It is not limited. For example, the positional relationship between the convex portion 60 and the concave portion 70 is such that when two or more container bodies 100 are stacked in one direction, the container body located on the upper side will be placed in the storage space of the container body located on the lower side. When the container bodies 100 are rotated 180° and stacked in a different direction, the bottom surface of the convex portion 60 and the bottom surface of the main body side wall portion 22 on the side of the concave portion 70 are , there is no particular limitation as long as it is placed on each placement surface.

Note that the shapes and positions of the convex portions and concave portions are not limited to the above-mentioned modified examples, and can be changed as appropriate. Furthermore, this modification is not limited to the second embodiment, but can also be applied to the first embodiment.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
A container (X) having a container body (amorphous polyethylene terephthalate (A-PET) and a medium container (polypropylene (PP))) shown in FIG. 2 in the first embodiment is filled with 15 strawberries each (strawberries After applying a sticker to the top of each strawberry (weighing around 20 g/piece), the strawberries were packaged. For packaging, "Suntech C Film" manufactured by Asahi Kasei Co., Ltd. (corresponding to the above-mentioned film (Y2)) was used. The entire container body of container (X) was covered with a film, and then heat treatment was performed for 3 seconds in a shrink tunnel set at 120° C. to heat shrink and obtain a package. The following measurements were performed on the package.

<Measurement of oxygen permeation rate and water vapor permeation amount>
The oxygen permeation rate and water vapor permeation amount were measured in accordance with JIS-K7126 (2006) or JIS-K7129B (2008).

<Transportation test>
A transportation test was carried out using a 3-ton truck (refrigerated vehicle), storing the packages (5 packs) in a freezer and traveling approximately 700 km.

(Storage test)
After the transportation test, each package was stored in a refrigerator at 5° C. for 10 days, then taken out from the refrigerator and evaluated for gas concentration and taste according to the following criteria.

-Gas concentration standards-
The oxygen concentration (O ₂ )/carbon dioxide concentration (CO ₂ ) inside the package after the storage test was measured using "Checkpoint 3" manufactured by MOCON.
(Evaluation points)
5 O ₂ : 5% to 10%, and CO ₂ : 5% or less 4 O ₂ : 5% to 10%, and CO ₂ : More than 5% to 10% 3 O ₂ : More than 10% to 15% Below, and CO ₂ : 5% or less 2 O ₂ : More than 10% and 15% or less, and CO ₂ : More than 5% and 10%
1 Other than the above

-Taste standards-
A taste test was conducted on the strawberries after the storage test.
(Evaluation points)
5: The taste was almost the same as before the storage test and was good.
4: Although the taste was slightly inferior to that before the storage test, it was good.
3: The taste was lower than before the storage test.
2: Some parts of the fruit were sore that they were unpalatable.
1: The fruit as a whole was painful and tasteless.

(number of rotations)
After the transportation test was completed, using the sticker affixed to the strawberry as a reference, the strawberry whose sticker was shifted from the starting position of the test was assumed to have rotated during transportation, and visually evaluated. In addition, the average number of rotations (5 packs) among 15 strawberries housed in one package was taken as the number of rotations.

(conductivity)
One of the five packages was opened.
Strawberries were placed one by one in a 200 g beaker containing 100 ml of purified water, and the strawberries were immersed in the water. After 20 minutes, the strawberries were taken out and the water in which they had been soaked was lightly filtered to remove dirt and the like, and the electrical conductivity of the water in which they had been soaked was measured.
The electrical conductivity was measured using a conductivity meter (model number ES-51) manufactured by HORIBA.
When a bruised strawberry is soaked in water, the ionic substances in the juice will dissolve from the scratched area, so the measured values were used as an indicator of the damage to the strawberry.
(evaluation)
A: Conductivity less than 15S/c B: Conductivity 15S/cm or more and less than 20S/cm C: Conductivity 20S/cm or more

<Comprehensive evaluation>
Taking into account the results of the transportation test and storage test, the performance as a package was comprehensively evaluated according to the following criteria.
(standard)
A: Very good B: Good C: Bad

[Example 2, Comparative Examples 1 to 9]
A package was produced in the same manner as in Example 1, except that the containers and films listed in the table below were used, and the same evaluation as in Example 1 was performed.

As shown in the table, the packaging bodies of Examples performed well in both the transportation test and the storage test.
On the other hand, Comparative Examples 1 and 5 using films and containers other than the film (Y) and container (X) according to the present invention had particularly poor results in the preservability test.
In addition, although Comparative Examples 2 to 4 and 8 to 9 using lids or films other than the container (X) according to the present invention and the film (Y) according to the present embodiment had good results in the transportation test, The results of the storage test were inferior. Moreover, Comparative Example 7 had poor results in both transportation and storage tests using the container (X) according to the present invention. This is because in Comparative Example 7, both the water vapor permeability and oxygen permeability of the film are outside the range of the embodiment of the present application, and rotting of the plants (soft fruits) occurs during transportation, so the results of the transportation test are It is assumed that it was bad.
Furthermore, in Comparative Example 6, both the water vapor permeability and the oxygen permeability of the film are within the range of the embodiment of the present application, but since a container other than the container (X) according to the present invention is used, the transportation test and The results of the storage test were inferior.

1, 10: Packaging body, 2,100: Container main body, 3: Medium container, 4: Air packing (buffer material), 5, 50: Film, 20: Accommodation space, 21: Main body bottom, 22: Main body side wall, 211: Main body leg, 31: Top plate, 32: Recess, 34: Medium container leg, 34c: Bent part, 311: Plant storage part, 312: Supported part, S: Strawberry (plant), 60: Recess , 70: Convex portion, 80A, 80B: Placement surface

Claims (6)

A package used for transporting plants,
a container body having a body bottom and a body side wall extending upward from a periphery of the body bottom, and forming a storage space surrounded by the body side wall above the body bottom;
an inner container having a top plate disposed in the storage space with a space between the bottom of the main body and the bottom of the main body;
The top plate has a plant storage part and a supported part provided outward from the plant storage part,
The plant storage section is provided with a plurality of recesses that are recessed downward and accommodate plants,
The supported part is provided with a medium container leg part extending downward from the top plate,
a container (X) in which the medium container is supported from below only by the legs of the medium container;
The entire container (X) is packaged, and the oxygen permeation rate is 13,000 to 33,000 cc/atm/m ² /day, the water vapor permeation rate is 40 to 80 g/m ² /day , and the heat A heat -shrinkable film (Y) having a shrinkage temperature of 70 to 130°C ;
A packaging body with. The package according to claim 1, wherein the heat-shrinkable film (Y) has a laminated structure. The heat-shrinkable film (Y) includes a pair of heat-sealing layers containing a resin containing 50% by mass or more of an ethylene-vinyl acetate copolymer having an MFR of 2.0 to 6.0 g/10 minutes, and A three-layer film having an inner layer containing a mixed resin of 50 to 10% by mass of density polyethylene and 50 to 90% by mass of linear low-density polyethylene, wherein the 90°C free shrinkage rate of the three-layer film is 15% or less, and The free shrinkage rate at 140°C is 70% or more, the inner layer has a gel fraction of 10 to 30% by mass, and the pair of heat seal layers each have a gel fraction of 20 to 40% by mass.
The package according to claim 1 or 2, which is a three-layer crosslinked film. A heat-shrinkable multilayer film in which the heat-shrinkable film (Y) has a heat-sealing layer and an inner layer, and the heat-sealing layer is laminated on the inner layer,
The heat-sealing layer contains an ethylene-α-olefin copolymer (A) containing ethylene and an α-olefin having 4 to 18 carbon atoms,
The inner layer contains 20 to 80% by mass of propylene-α-olefin copolymer (B) having a density of 0.880 to 0.910 g/cm ³ and a density of 0.850 to 0.900 g/cm ³ 80 to 20% by mass of a propylene-α-olefin copolymer (C) that is amorphous or has a melting peak temperature of less than 120°C,
The propylene-α-olefin copolymer (B) has the following properties (B1) to (B4), and the propylene-α-olefin copolymer (C) has the following properties (C1) to The package according to claim 1 or claim 2, which satisfies (C2).
(B1) Melting peak temperature (Tmp) is 120-165°C
(B2) The difference between melting start temperature (Tms) and melting end temperature (Tme) is 30 to 70°C
(B3) The difference between the melting peak temperature (Tmp) and the melting end temperature (Tme) is 3 to 30°C
(B4) Heat of fusion is 20 to 50 J/g
(C1) Heat of fusion is 40 J/g or less (C2) TanΔ peak temperature determined by dynamic viscoelasticity measurement is -30°C to 0°C The package according to any one of claims 1 to 4, wherein the plant is a fruit. The main body side wall portion of the container main body has a convex portion formed such that a part of the wall surface including the upper end portion bulges from the inner circumferential side to the outer circumferential side of the container main body, and is provided at a position symmetrical to the convex portion. 6. The package according to claim 1, further comprising a recessed portion formed such that a portion of the wall surface is recessed from the outer circumferential side to the inner circumferential side.