Manufacturing method for freshness-preserving packaging container for fruits and vegetables

Abstract

To provide a new packaging container capable of holding freshness of fruits and vegetables excellently even in an environment where temperature is variously changing.SOLUTION: A fruit and vegetable freshness-retaining packaging container is configured of a synthetic resin film having a through hole. The synthetic resin film has at least a first layer and a second layer. A first resin included in the first layer and a second resin included in the second layer have a common structural unit. In a DSC curve obtained by differential scanning calorimetry of the synthetic resin film constituting the fruit and vegetable freshness-retaining packaging container from 25°C to 250°C at a heating temperature of 5°C / minute, at least two melting peaks P1 and P2 are observed, and when the peak top temperature of the melting peak P1 is T1 and the peak top temperature of the melting peak P2 is T2, the absolute value of the difference between T1 and T2 is 3 to 40°C.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a freshness-maintaining packaging container for fruits and vegetables, a package containing fruits and vegetables, and a method for maintaining the freshness of fruits and vegetables, and more specifically to a freshness-maintaining packaging container for fruits and vegetables having a specific configuration, a package containing fruits and vegetables in which fruits and vegetables are packaged in the freshness-maintaining packaging container, and a method for packaging fruits and vegetables in the freshness-maintaining packaging container to suppress deterioration of the freshness of the fruits and vegetables. [Background technology]

[0002] Vegetables, fruits, and other fresh produce continue to respire even after they have been harvested. As a result, the fresh produce loses its freshness due to the consumption of energy through its own respiration during storage, distribution, or preservation after harvest. Therefore, studies have been conducted to prevent deterioration of freshness of fruits and vegetables by wrapping them in appropriate wrapping materials (for example, synthetic resin films).

[0003] As an example, Patent Document 1 describes a paper with a basis weight of 30 to 70 g / m 2 The document describes a moisture-permeable and breathable packaging material in which a polyethylene terephthalate (PET) nonwoven fabric, a printed layer, and a polyolefin resin layer are laminated in this order. The packaging material is characterized in that a plurality of holes are formed in a predetermined area of ​​the polyolefin resin layer, penetrating the polyolefin resin layer.

[0004] As another example, Patent Document 2 describes a laminated film for packaging fresh vegetables, which is composed of at least two layers, an outer layer and an innermost layer. In this film, the outer layer is composed of a biaxially oriented film-like material mainly composed of crystalline polypropylene, and the innermost layer is a film-like material composed of an olefin polymer having a melting point 10 to 90° C. lower than that of the outer layer. It is described that the innermost layer has a thickness of 4 to 30 μm and a surface roughness of 0.5 μm or less in terms of center line average roughness. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-231723 A [Patent Document 2] Japanese Patent Application Publication No. 9-290865 Summary of the Invention [Problem to be solved by the invention]

[0006] When a freshness-preserving packaging container for fruits and vegetables is constructed using a synthetic resin film, holes (typically through holes) may be provided in the synthetic resin film in order to adjust the breathability, etc. In other words, fruits and vegetables may be packaged using a perforated synthetic resin film (or a packaging container constructed using the film). In particular, in recent years, it has become common to package fruits and vegetables in packaging containers that have holes of an appropriate number, density and diameter, taking into consideration the respiration of the fruits and vegetables. There are various methods for forming holes in a synthetic resin film, such as laser and hot needle methods.

[0007] The present inventors, while studying further improvements in the performance of packaging containers made of perforated synthetic resin films, have found the following problems. In general, in the distribution of fruits and vegetables, the storage temperature of the fruits and vegetables is not constant, and the temperature environment of the fruits and vegetables changes in various ways. The present inventors have found that deterioration of the fruits and vegetables is likely to progress in such an environment where the temperature changes in various ways. Therefore, the present inventors have conducted research into new packaging containers that can maintain the freshness of fruits and vegetables in a good condition even in environments with various changes in temperature. [Means for solving the problem]

[0008] The present inventors have conducted research from various perspectives in order to solve the above problems, and have found that the location of maxima and the number of maxima in a DSC curve (horizontal axis: temperature, vertical axis: heat flow (heat capacity)) obtained by differential scanning calorimetry (DSC) of a perforated synthetic resin film constituting a packaging container for preserving the freshness of fruits and vegetables are likely to be related to solving the problems. Based on this finding, further research was carried out and the invention provided below was completed.

[0009] According to the present invention, A freshness-preserving packaging container for fruits and vegetables made of a synthetic resin film having through holes, The synthetic resin film comprises at least a first layer and a second layer, a first resin contained in the first layer and a second resin contained in the second layer have a common structural unit, In a DSC curve obtained by subjecting the synthetic resin film to differential scanning calorimetry from 25° C. to 250° C. at a heating temperature of 5° C. / min, at least two melting peaks P 1 and P 2 was observed, The melting peak P 1 The peak top temperature is T 1 The melting peak P 2 The peak top temperature is T 2 Then, T 1 and T 2 The absolute value of the difference between the temperature and humidity is 3 to 40°C. is provided.

[0010] Further, according to the present invention, A package containing fruits and vegetables, the fruits and vegetables being sealed in the freshness-preserving packaging container for fruits and vegetables is provided.

[0011] Further, according to the present invention, A method for preserving the freshness of fruits and vegetables, comprising packaging the fruits and vegetables using the freshness-preserving packaging container for fruits and vegetables. is provided. Effect of the Invention

[0012] According to the present invention, the freshness of fruits and vegetables can be well maintained even in environments where the temperature changes widely. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view of a manufacturing device for explaining a method of perforating a synthetic resin film. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a main part of a manufacturing apparatus for explaining a method of perforating a synthetic resin film. [Diagram 3] FIG. 2 is a perspective view of a manufacturing apparatus for explaining a method of perforating a synthetic resin film. [Figure 4] 1 is a DSC curve obtained by differential scanning calorimetry of a part of the synthetic resin film constituting the packaging container of Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all drawings, similar components are given similar symbols and descriptions thereof are omitted where appropriate. In order to avoid complexity, (i) when there are multiple identical components in the same drawing, only one of them is given a reference symbol and not all of them, or (ii) especially in Figure 2 and subsequent figures, components similar to those in Figure 1 are not given a reference symbol again. All drawings are for illustrative purposes only. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to the actual objects.

[0015] In this specification, the term "approximately" means that a range taking into consideration manufacturing tolerances, assembly variations, and the like, is included, unless otherwise specified explicitly. In this specification, the expression "a to b" in the explanation of a numerical range means from a to b, unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass to 5% by mass."

[0016] In the description of groups (atomic groups) in this specification, when a description is made without specifying whether the group is substituted or unsubstituted, the description includes both groups having no substituents and groups having a substituent. For example, an "alkyl group" includes not only an alkyl group having no substituents (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, the term "(meth)acrylic" refers to a concept that includes both acrylic and methacrylic. The same applies to similar terms such as "(meth)acrylate."

[0017] In the following, freshness-preserving packaging containers for fruits and vegetables may be referred to simply as "packaging containers" or "containers." Among the characteristics of packaging containers described below, for characteristics whose values ​​may vary due to thermal expansion / contraction caused by temperature, etc., measurements taken in an environment of 25°C may be used. However, this does not apply to characteristics for which measurement / environmental conditions are specifically stated.

[0018] <Freshness-preserving packaging containers for fruits and vegetables> The fruit and vegetable freshness-preserving packaging container of this embodiment is made of a synthetic resin film having through holes. The synthetic resin film herein comprises at least a first layer and a second layer. The first resin contained in the first layer and the second resin contained in the second layer have a common structural unit. In addition, in a DSC curve obtained by differential scanning calorimetry of the synthetic resin film constituting the freshness-preserving packaging container for fruits and vegetables of this embodiment from 25° C. to 250° C. at a heating temperature of 5° C. / min, at least two melting peaks P 1 and P 2 is observed. Here, the melting peak P 1 The peak top temperature is T 1 and the melting peak P 2 The peak top temperature is T 2 Then, T 1 and T 2 The absolute value of the difference is 3 to 40 degrees Celsius.

[0019] The mechanism by which such a packaging container can maintain the freshness of fruits and vegetables in an environment with various temperature changes is not necessarily clear. However, based on the inventors' supposition, it can be explained as follows. Note that the scope of the present invention is not limited by the following explanation.

[0020] When fruits and vegetables are packaged in perforated synthetic resin film, the holes in the film are thought to expand or contract due to temperature changes. This expansion or contraction is thought to allow an appropriate amount of outside air to be taken in / inside air to be expelled in response to changes in the respiration rate of the fruits and vegetables due to temperature. (For information on the expansion or contraction of holes in a perforated synthetic resin film due to temperature changes, see, for example, JP 2014-140349 A.)

[0021] However, if the temperature changes rapidly and / or irregularly, the holes may not expand or contract properly, resulting in an inability to take in or expel the proper amount of outside air. This can lead to the deterioration of fruit and vegetables.

[0022] In this embodiment, the synthetic resin film constituting the container has a multi-layer structure including at least a first layer and a second layer. The first resin contained in the first layer and the second resin contained in the second layer have a common structural unit. By using a first resin contained in the first layer and a second resin contained in the second layer that have common structural units, it is possible to roughly match the expansion / contraction properties of the first layer and the second layer, and because the synthetic resin film is multi-layered, it is believed that when one layer attempts to expand / contract abnormally, the other layer can suppress it to some extent.

[0023] Further, in this embodiment, the synthetic resin film has at least two melting peaks P in a DSC curve obtained by differential scanning calorimetry from 25° C. to 250° C. at a heating temperature of 5° C. / min. 1 and P 2 was observed, and (2) the melting peak P 1 The peak top temperature is T 1 and the melting peak P 2 The peak top temperature is T 2 Then, T 1 and T 2 The absolute value of the difference was 3 to 40°C. The above (1) and (2) mean that various, moderately different, crystalline and orientation states exist in the synthetic resin film that constitutes the container. This "various moderately different crystal and orientation states existing in one synthetic resin film" is believed to make it easier to "average" the change in pore size caused by temperature change, even in the case of sudden / irregular temperature change. In other words, it is believed that it is easier to obtain an appropriate change in pore size even in the case of sudden / irregular temperature change. Furthermore, since appropriate pore opening changes can be easily achieved even with sudden / irregular temperature changes, it is assumed that the freshness of fruits and vegetables can be well maintained even under various storage and transportation conditions.

[0024] In particular, in this embodiment, the first resin contained in the first layer and the second resin contained in the second layer have common structural units (i.e., similar first and second resins are used), but the film is newly designed so that at least two melting peaks are observed in the DSC curve, thereby achieving a favorable freshness-preserving effect for fruits and vegetables even against sudden / irregular temperature changes.

[0025] In addition, when manufacturing the packaging container of this embodiment, (1) the selection of the material constituting the resin film, (2) the manufacturing method of the resin film, etc. are important. These will be described in detail later, but for example, in (1) the selection of the material, the packaging container of this embodiment is easily obtained by selecting homopolypropylene as the first resin and random polypropylene as the second resin, selecting the first resin and the second resin with melting points different to some extent, etc. In addition, in (2) the manufacturing method of the resin film, it is preferable to apply a method such as forming the first layer and the second layer by a coextrusion method, appropriately adjusting the thicknesses of the first layer and the second layer at that time, and performing appropriate biaxial stretching.

[0026] We will provide additional information on differential scanning calorimetry and DSC curves. Differential scanning calorimetry can be performed using a commercially available differential scanning calorimeter. For example, it can be performed using an SII Corporation device (product number: DSC6220) under the following heating conditions: 5°C / min, 25 to 250°C. Data can be analyzed using SII Corporation's software that comes with the device.

[0027] In differential scanning calorimetry, a part of the synthetic resin film constituting the packaging container is cut out to prepare a measurement sample. In this case, it is preferable to select a part without holes as the cut-out part (because appropriate measurement may not be possible around the holes due to melting of the resin when the holes are drilled).

[0028] Peak top temperature T 1 and T 2 The difference between the temperatures should be 3 to 40°C within the temperature range of 25 to 250°C. 1 and T 2 The absolute value of the difference is preferably 3 to 10°C, and more preferably 4 to 9°C. T 1 The value itself is not particularly limited as long as it is within a temperature range of 25 to 250° C. From the viewpoints of material availability and ease of design and manufacture, it is, for example, 140 to 180° C., and preferably 150 to 170° C. T 2 The value of T is not particularly limited as long as it is within the temperature range of 25 to 250° C. For example, T 1 can be about the same. If three or more melting peaks are observed in a DSC curve, the difference between the highest peak top temperature and the lowest peak top temperature is preferably 3 to 40°C.

[0029] Peak P 1 and the peak P 2 The lower height of the linear baseline of the DSC curve is defined as H 1 The higher height is H 2 Then, H 1 / H 2 The value of H is preferably 0.3 to 0.9, and more preferably 0.4 to 0.8. 1 Size and H 2 It is believed that by having the pores of similar size, it becomes easier to obtain consistent and appropriate changes in pore opening even in the event of sudden / irregular temperature changes, resulting in better freshness-retaining performance.

[0030] The material, properties, etc. of the packaging container of this embodiment will be described in more detail below.

[0031] ·material The raw material (material) of the synthetic resin film constituting the packaging container may be any synthetic resin. For example, the first layer of the synthetic resin film preferably contains, as the first resin, at least one resin selected from the group consisting of polyethylene, ethylene copolymer, homopolypropylene, random copolymer of propylene, polyvinyl chloride, polystyrene, (meth)acrylic resin, polyester resin, and polyamide resin. The second layer of the synthetic resin film also preferably contains at least one resin among the above. However, as described above, the first resin and the second resin have a common structural unit.

[0032] Here, the first resin and the second resin "have a common structural unit" means that the first resin and the second resin have a structural unit derived from a monomer of the same chemical structure. For example, when the first resin and the second resin are both homopolypropylene, this naturally corresponds to the case where they "have a common structural unit". As another example, a case where the first resin is homopolypropylene and the second resin is a random copolymer of propylene also falls under the category of a case where "they have a common structural unit". Both the first resin and the second resin have a structural unit (-CH 2 -CH(CH 3 )-) in common.

[0033] In one embodiment, the first layer and / or the second layer may contain two or more types of resin. 1 and T 2 The absolute value of the difference between 1 / H 2 This makes it easier to design the values ​​of, etc., to the desired values. For example, it may be preferred that the first layer comprises homopolypropylene and the second layer is a blend of homopolypropylene and a random copolymer of propylene, where the first resin is homopolypropylene and the second resin is a random copolymer of propylene.

[0034] The first layer and the second layer preferably contain homopolypropylene and / or a random copolymer of propylene. Polypropylene-based polymers have advantages such as low cost and availability, as well as a high peak top temperature T 1 Or T 2 It also has the advantage that it is easy to design it to an appropriate value. Examples of the random copolymer of propylene include a copolymer of propylene and ethylene, and a copolymer of propylene and an α-olefin having 4 to 10 carbon atoms.

[0035] By selecting the appropriate first and second resins, the peak top temperature T 1 and T 2 It is easy to design a synthetic resin film (and packaging container) in which the absolute value of the difference between the temperature of the first resin and the temperature of the second resin is 3 to 40°C. For example, by selecting homopolypropylene as the first resin and a random copolymer of propylene as the second resin, the T 1 and T 2 It is easy to obtain a synthetic resin film in which the absolute value of the difference is 3 to 40°C.

[0036] As another aspect of the selection of the first resin and the second resin, it is also possible to select two types of resins having different melting points and / or glass transition points. For example, the first resin may have a melting point of 150 to 170° C. (preferably 155 to 165° C.), and the second resin may have a melting point of 130 to 150° C. (preferably 135 to 145° C.).

[0037] The first layer and / or the second layer may optionally contain additives such as an anti-fogging agent.

[0038] Layer structure, thickness, etc. The layer structure and thickness of the synthetic resin film constituting the packaging container can basically be appropriately designed based on the strength, handling properties, etc. of the packaging container. The first layer has a thickness of, for example, 5 to 50 μm, preferably 7 to 40 μm. The thickness of the second layer may be, for example, approximately the same as that of the first layer. The thickness ratio of the first layer to the second layer (thickness of the second layer / thickness of the first layer) is, for example, 0.2 to 5, and preferably 0.25 to 4. From the viewpoint of the above-mentioned estimated mechanism, it is considered preferable that the thickness of the first layer and the thickness of the second layer are approximately the same.

[0039] The synthetic resin film may have a two-layer structure consisting of only the first layer and the second layer, or may have a three-layer structure including other layers, such as an adhesive layer for bonding the first layer and the second layer, and a sealant layer for improving heat sealability. The other layer may be present in any location, for example, between the first layer and the second layer, on the opposite side of the first layer to the second layer, or on the opposite side of the second layer to the first layer.

[0040] The overall thickness of the synthetic resin film is, for example, 10 to 100 μm, and preferably 20 to 40 μm. By setting the thickness to an appropriate value, it is possible to improve the handleability of the packaging container while obtaining an appropriate strength.

[0041] About holes As described above, the synthetic resin film constituting the packaging container of this embodiment has through holes.

[0042] The synthetic resin film constituting the packaging container may have only one through hole, or may have multiple (two or more) through holes. In other words, one packaging container is provided with one or two or more through holes. The advantage of having multiple through holes is that it is easier to take in the appropriate amount of outside air / exhaust the appropriate amount of inside air in response to changes in the respiration rate of fruits and vegetables due to temperature. Also, by having multiple through holes, even if the change in the opening rate due to temperature varies from hole to hole, the variation is "averaged out," making it easier to obtain a more appropriate change in the opening rate for the entire container.

[0043] The upper limit of the number of through holes in the synthetic resin film constituting the packaging container is not particularly limited, but is preferably not more than 50, and more preferably not more than 40. By not having too many through holes, excessive ventilation is suppressed, and it is believed that an environment favorable for preserving the freshness of fruits and vegetables, known as a modified atmosphere (MA environment), can be more easily obtained.

[0044] The diameter of the through-hole is preferably 30 to 500 μm, more preferably 50 to 300 μm, and further preferably 60 to 200 μm. By appropriately designing the diameter of the holes, it is believed that the intake of outside air / exhaust of inside air can be sufficiently controlled, and deterioration of the freshness of fruits and vegetables can be further suppressed. In addition, when the synthetic resin film constituting the packaging container has multiple holes, it is preferable that the diameters of all the through holes are within the above numerical range. This is for ease of manufacture. In addition, it is easier to match the approximate expansion / contraction properties of multiple holes, and as a result, it is easier to "average" the change in hole opening due to temperature change.

[0045] Here, "diameter of a hole" refers to the diameter of a perfect circle (equivalent diameter of a perfect circle) having the same area as the opening area of ​​the hole, if the shape of the hole cannot be considered to be approximately circular. The holes are preferably substantially circular or elliptical, but may be slit-shaped or the like.

[0046] As described above, when there are multiple holes, it is preferable that the diameters of all the holes fall within the above-mentioned diameter range. However, when there are multiple holes, the present invention does not exclude an embodiment in which the diameter of some of the holes is outside the range of 30 to 500 μm. For example, the diameter of some of the holes may be less than 30 μm. This is because, even if the diameter of some of the holes is 30 μm or less, as long as the diameter of the other holes is 30 to 500 μm, it is considered that appropriate ventilation is achieved inside and outside the container, and the effect of preserving the freshness of fruits and vegetables can be obtained.

[0047] It is preferable that there is a "hump" around the hole. Specifically, the maximum thickness of the resin film in the region within 10 mm from the outer periphery of the hole is T max , the minimum thickness is T min Then, T max / T min is preferably 1.05 or more, more preferably 1.2 or more, and even more preferably 1.5 or more. max / T minis preferably 8 or less, more preferably 6.5 or less, and even more preferably 5 or less. Here, "the area within 10 mm from the outer periphery of the hole" refers to, for example, the range in the synthetic resin film that constitutes the packaging container, from the intersection of a straight line with the periphery of the hole to a point 10 mm away in the opposite direction from the center point of the through hole, when a straight line is drawn from the center point of the hole to the periphery (outer periphery) of the hole. T max and T min For a method for measuring the thickness of the film (i.e., a method for measuring the local film thickness), see the Examples section below.

[0048] It is believed that the presence of the "bumps" around the holes makes the structure of the holes and their surroundings more robust. It is also believed that the diameter and shape of the holes are more likely to be stably maintained even if the temperature changes are repeated. As a result, it is believed that the freshness preservation effect of fruits and vegetables can be more reliably obtained. The "bumps" around the holes can be formed, for example, by perforating a synthetic resin film with a laser, as described below.

[0049] As an alternative to the "number" of holes, the packaging container may be designed using the "density" of the holes, that is, the number of holes per unit area of ​​the inner surface of the packaging container, as an index. The density of the holes is, for example, 1 to 1500 holes / m 2 , preferably 2 to 1000 pieces / m 2 can be adjusted within the range.

[0050] From another viewpoint, the ventilation inside and outside the packaging container may be adjusted by using the "area" of the holes provided in the packaging container as an index. Specifically, the total open area of ​​the holes in the packaging container is S h , the area of ​​the inner surface of the packaging container is S t Then, the formula: (S h / S t The open area ratio (%) defined as 1.0×10 -9 ~1.0×10 -4 It is preferable that the ratio is 1.0×10 -8 ~1.0×10-3 It is more preferable that:

[0051] In addition, the "expansion or contraction due to temperature change" of the holes, which has been mentioned several times in the above explanation, can be quantitatively expressed, for example, as follows. The open area ratio at 5℃ (defined as above) is R 5 , the open area ratio at 40℃ is R 40 Then, {(R 40 -R 5 ) / R 5 The value of the rate of change in pore opening, represented by}×100, is, for example, −5 to 20, preferably −4 to 15, and more preferably −3 to 12.

[0052] In order to make the holes expand / contract appropriately due to temperature changes, it is important to perform the perforation appropriately. For example, in the case of perforation using a laser described below, it is important to precisely control each factor such as the shape of the support table on which the film to be perforated is mounted, the laser energy, and the laser irradiation distance. It is believed that by controlling the above factors highly when forming holes in a film, it is possible to obtain holes without distortion. That is, by controlling the above factors highly when forming holes in a film, it is possible to form holes without distortion. This provides a peripheral reinforcement effect on the outer periphery of the holes, and it is believed that the area of ​​the holes changes appropriately with the expansion and contraction of air due to temperature changes.

[0053] Gas permeability By appropriately adjusting and designing the permeability of the synthetic resin film that makes up the packaging container to gases such as oxygen, it is possible to more favorably control the respiratory environment for fruits and vegetables.

[0054] Specifically, the oxygen permeability of the resin film constituting the packaging container is preferably 1×10 2 ~1.5×10 6 cc / m 2 ·day·atm, preferably 5×10 2 ~1×10 6 cc / m2 ·day·atm. The oxygen permeability here is measured under conditions of 23°C and 50% RH.

[0055] The oxygen permeability can be measured, for example, using an oxygen permeability measuring device manufactured by MOCON (OXYTRAN (registered trademark) OX-TRAN 1 / 50) according to a method in accordance with Appendix B of JIS K7126-2. Alternatively, the oxygen permeability value can be calculated from the oxygen concentration gradient by measuring the oxygen concentration inside the packaging container immediately after filling it with nitrogen and after it has been left for a certain period of time after filling it with nitrogen.

[0056] The water vapor permeability of the synthetic resin film constituting the packaging container is preferably 0 to 300 g / m 2 ·day, preferably 2 to 200 g / m 2 ·day.

[0057] - Shape, size, etc. of packaging container The shape and size of the packaging container of the present embodiment are not particularly limited as long as it is capable of packaging fruits and vegetables. The shape of the packaging container is typically bag-like, more specifically, quadrangular (rectangular, square, etc.) bag-like. By way of example only, the size of a packaging container for packaging fruits and vegetables for general consumers may be approximately 120 mm×200 mm to 250 mm×350 mm.

[0058] In the packaging container, the "front and back" of the synthetic resin film are not particularly limited. For example, when a bag-shaped packaging container is made using a synthetic resin film, the first layer may be located inside the second layer, or the second layer may be located inside the first layer. However, when there is a difference in melting point between the first layer and the second layer, it is preferable that the layer with the lower melting point is located closer to the inside from the viewpoint of heat sealability.

[0059] <Package containing fruits and vegetables, and method for preserving the freshness of fruits and vegetables> By sealing the fruits and vegetables in the above-mentioned freshness-preserving packaging container for fruits and vegetables, a package containing the fruits and vegetables can be produced. Also, by packaging the fruits and vegetables in the above-mentioned freshness-preserving packaging container for fruits and vegetables, the freshness of the fruits and vegetables can be preserved (deterioration of the fruits and vegetables can be suppressed).

[0060] For example, first, a freshness-preserving packaging container for fruits and vegetables is prepared, and an appropriate amount of fruits and vegetables is placed in its internal space. After that, the opening of the packaging container is heat-sealed (heat-sealing process) to form a heat-sealed portion (seal width is typically about 10 mm). Through the above procedure, a package containing fruits and vegetables can be obtained in which the fruits and vegetables are packaged. The freshness of the packaged fruits and vegetables can then be preserved (deterioration of the fruits and vegetables can be suppressed). The opening may be closed not only by heat sealing but also by adhesive tape, a rubber band, a string, a sealable lid, etc. In short, any method of closure may be used as long as it sufficiently restricts the inflow and outflow of gas from the opening.

[0061] There is no particular limitation on the fruits and vegetables that can be packaged. Specific examples of fruits and vegetables include Chinese radish, spinach, Japanese mustard spinach, Mizuna, Mibuna, asparagus, Kuusinsai, lettuce, thyme, sage, parsley, Italian parsley, rosemary, oregano, lemon balm, chives, lavender, salad burnet, lamb's ear, rocket, dandelion, nasturtium, basil, arugula, watercress, molokheiya, celery, kale, green onion, cabbage, Chinese cabbage, garland chrysanthemum, lettuce, lettuce, and soybean paste. These include butterbur, turnip, bok choy, mitsuba, parsley, brussels sprouts, broccoli, cauliflower, myoga, radish, carrot, burdock, radish, turnip, sweet potato, potato, Chinese yam, yam, taro, Japanese yam, green pepper, paprika, shishito pepper, cucumber, eggplant, tomato, cherry tomato, pumpkin, bitter melon, okra, sweet corn, edamame, snow peas, green beans, broad beans, fungi, mushrooms, etc. It is also effective on citrus fruits, apples, pears, grapes, blueberries, persimmons, strawberries, and other fruits and cut flowers.

[0062] The fruits and vegetables may be cut, specifically cut vegetables and fruits.

[0063] The amount of fruit or vegetable contained in a bag may vary depending on the size of the bag, the type of fruit or vegetable, etc. For fruit or vegetable destined for general consumers, the amount is, for example, 50 to 1000 g, and preferably 100 to 800 g.

[0064] <Manufacturing method for freshness-preserving packaging containers for fruits and vegetables> A method for producing the fruit and vegetable freshness-preserving packaging container of this embodiment will be described. The production can be roughly divided into (1) a synthetic resin film preparation process, (2) a perforation process for providing holes in the synthetic resin film, and (3) a process for shaping the synthetic resin film into a packaging container. In addition, other processes may be included. The order of steps (2) and (3) is not particularly limited, but from the viewpoint of productivity, it is preferable to carry out step (3) after step (2). These steps will be described below.

[0065] (1) Preparation process of synthetic resin film The film can be produced by a method such as an extrusion method (T-die method, inflation method), a calendaring method, a dry lamination method, an extrusion lamination method, etc. That is, by using any of these methods, a synthetic resin film having a first layer containing a first resin and a second layer containing a second resin can be obtained. In particular, two-layer (multi-layer) coextrusion by a T-die method is preferred from the standpoint of ease of controlling conditions.

[0066] The selection of materials for the first layer, second layer, and each layer, and the thickness of each layer have already been described, and therefore will not be described again. As already described, by appropriately selecting the type of the first resin contained in the first layer and the type of the second resin contained in the second layer, 1 and T 2 The absolute value of the difference can be easily set to 3 to 40 degrees Celsius.

[0067] In addition to or apart from the selection of the materials for each layer, the film formation conditions (especially the cooling conditions) can also be devised to improve the T 1 and T 2 The absolute value of the difference between the melting point and the melting point of the resin material may be set to 3 to 40° C. This is because, in general, the more rapidly a resin material is cooled from a molten state, the lower its crystallinity becomes, and the lower its melting point (correlated with the peak top temperature of the melting peak in the DSC curve) tends to become. Specifically, during film production, a low-temperature roll can be placed on only one side of the film and the cooling conditions can be made different on the front and back of the film, thereby making the degree of crystallinity of the resin in the first layer different from the degree of crystallinity of the resin in the second layer.

[0068] It is also preferable to perform a suitable stretching process in terms of controlling the crystalline state in the film, etc. For example, it is preferable to cool and solidify the resin extruded from a T-die, and then sequentially stretch the resin by about 3 to 7 times (preferably about 4 to 6 times) in the machine direction and further by about 7 to 11 times (preferably about 8 to 10 times) in the width direction.

[0069] (2)Drilling process Holes are made in the synthetic resin film prepared in the preparation step (1). Methods for making holes include laser processing, punching, and hot needle processing. Among these, laser processing is preferred from the viewpoints of ease of controlling the properties of the holes, ease of maintenance of the manufacturing equipment (holes can be made without contacting the film, so it is less likely to become dirty), and ease of making the aforementioned "bumps."

[0070] An example of a method for drilling holes by laser processing will now be described in detail. 1 and 2 are cross-sectional views of a manufacturing apparatus for explaining a method for drilling holes using a laser, and Fig. 3 is a perspective view of a main part. The following description will be given with reference to these figures.

[0071] 1, when the synthetic resin film 12 unwound from the unwinding roll 11 passes between the laser irradiating device 13 and the rotation support roll 14, the laser irradiating device 13 can irradiate the synthetic resin film 12 with a pulsed laser beam. In this way, holes having substantially the same shape as the shape of the irradiated beam can be formed in the synthetic resin film 12. The synthetic resin film 12 having holes formed therein by this method is taken up by a take-up roll 15. Two guide rolls 16 may be provided before and after the rotation support roll 14.

[0072] The upper end of the rotating support roll 14 can be positioned above the line connecting the upper ends of the two guide rolls 16. This allows the synthetic resin film 12 to be pressed against the rotating support roll 14 so as to be in close contact with it, making it possible to determine the position of the laser irradiation and to prevent the occurrence of vertical wrinkles.

[0073] 1, the unwinding roll 11 and the take-up roll 15 can be provided via the rotating support roll 14. In this manufacturing apparatus of FIG. 1, the guide roll 16 can be provided between the rotating support roll 14 and the unwinding roll 11, and between the rotating support roll 14 and the take-up roll 15. The floating roll 17 can be provided between the unwinding roll 11 and the guide roll 16, and between the guide roll 16 and the take-up roll 15. In this manner, the floating roll 17 can apply an appropriate tension to the synthetic resin film 12.

[0074] The laser irradiation device 13 is provided with a compressed gas introduction passage 18, so that compressed gas can be blown onto the synthetic resin film 12 along the laser beam from a nozzle tip 19 (see FIG. 2) during laser irradiation.

[0075] FIG. 2 is an enlarged cross-sectional view of a main part of the laser irradiation device 13 in the manufacturing apparatus shown in FIG. As shown in FIG. 2, the synthetic resin film 12 can be made to travel below a nozzle tip 19 of a laser irradiation device 13 .

[0076] The pulsed laser 20 passes through a light guide 21 and is focused by an output optical unit (lens) 22, becoming a conical beam 23, which can be irradiated onto the synthetic resin film 12 from the nozzle tip 19. In this case, the inner diameter of the nozzle tip 19 is made larger than the beam diameter of the passing pulsed laser 20. In addition, it is preferable that the focal position of the pulsed laser 20 focused by the output optical unit (lens) 22 is set to a position slightly outside the film from the surface of the synthetic resin film 12 opposite the laser incident surface. By intentionally setting the focal position outside the film, it is easy to obtain holes whose opening areas are different on the inner and outer surfaces.

[0077] By irradiating the synthetic resin film 12 with the conical beam 23, the beam irradiated portion of the synthetic resin film 12 melts, decomposes, and volatilizes, forming a hole 24. In addition, at this time, a "hump" can usually be formed around the hole due to the melting of the synthetic resin film 12, etc.

[0078] The pitch of the holes 24 punched in the synthetic resin film 12 can be adjusted by the running speed of the synthetic resin film 12 and the pulse frequency of the pulse laser 20. Since one laser irradiation device can usually open 20 to 1000 holes 24 per second, it is possible to increase the running speed of the synthetic resin film 12 and achieve high productivity. The running speed of the synthetic resin film 12 is, for example, about 60 m / min. The pulse frequency of the pulse laser 20 is, for example, about 10 Hz.

[0079] The shape of the hole 24 drilled in the synthetic resin film 12 is approximately the same as the shape of the conical beam 23 passing through the synthetic resin film 12, and it is possible to always drill holes of approximately the same shape. The truncated cone hole can be made closer to a cylindrical shape by increasing the focal length of the output optical section (lens) 22.

[0080] By appropriately moving the laser irradiation device 13 during laser irradiation, the shape of the hole can be made substantially elliptical instead of substantially circular.

[0081] As described above, the compressed gas introduction path 18 is provided near the nozzle tip 19 of the light guide path 21 in the laser irradiation device 13. This makes it possible to blow compressed gas onto the synthetic resin film 12 along the laser beam during laser irradiation.

[0082] The flow rate of the compressed gas is preferably set to a wind speed at the nozzle tip 19 of 2 to 10 m / s, and more preferably set to 3 to 6 m / s, so that decomposition products generated by perforation do not enter through the nozzle tip 19 and contaminate the output optical part (lens) 22. The pressure of compressed gas is, for example, 1.0 kg / cm 2 (gauge pressure) or so.

[0083] The compressed gas is not particularly limited, and may be, for example, compressed air or an inert gas such as nitrogen gas or carbon dioxide gas. Compressed air is safe to handle and is advantageous in terms of cost. Inert gas can suppress oxidation of decomposition products of the plastic film and reduce soot, charring, blackening, etc.

[0084] In this perforation method, the surface of the synthetic resin film 12 opposite the laser incident surface is brought into contact with a rotating support roll 14 , and the synthetic resin film 12 is supported by the rotating support roll 14 . 3, the rotating support roll 14 is preferably provided with grooves 25 corresponding to the laser irradiation positions. This allows the decomposition products of the synthetic resin film 12 to be volatilized from the side opposite to the laser incident surface.

[0085] 3 has five grooves 25. When five laser irradiation devices are used together with such a rotating support roll 14, five rows of holes can be formed in the synthetic resin film 12.

[0086] The type of the laser light source is not particularly limited. For example, a ruby ​​laser, a neodymium YAG laser, a neodymium glass laser, a carbon dioxide gas laser, etc. can be mentioned. Among these, a carbon dioxide gas laser is particularly suitable for use because it has high energy efficiency, high output, and is easy to remove heat. The power of the laser may be, for example, about 150 watts.

[0087] According to the perforation method described herein, holes can be formed in a resin film at high speed with good productivity. Since the shape of the holes is determined by the beam shape of the pulsed laser, holes of a substantially constant shape can always be formed. In addition, most of the resin film material in the area perforated by the laser decomposes and volatilizes, and is blown away by the compressed gas, so the output optical section (lens) of the laser irradiation device is not contaminated by decomposition products. Furthermore, by selecting the number of laser irradiation devices and adjusting the pulse laser period and the running speed of the resin film, the position and density of the holes can be changed to desired values.

[0088] The perforation method described herein allows for a high degree of control over the diameter and location of the holes, etc. Selection of the film material and the laser processing conditions will be described in more detail in the examples below.

[0089] (3) The process of forming the synthetic resin film into a packaging container As a method for forming the porous synthetic resin film into a packaging container, any known method can be applied without any particular limitation. For example, as described in the Examples below, a bag-shaped packaging container can be manufactured by cutting two perforated synthetic resin films into rectangles of suitable size, stacking them, and heat-sealing three of the four sides of the rectangle. The seal width of the heat seal is, for example, about 10 mm. Of course, any method other than the above can be applied as long as it can produce a packaging container having a shape suitable for packaging fruits and vegetables.

[0090] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. Below, examples of reference forms are given. 1. A freshness-preserving packaging container for fruits and vegetables made of a synthetic resin film having through holes, The synthetic resin film comprises at least a first layer and a second layer, a first resin contained in the first layer and a second resin contained in the second layer have a common structural unit, In a DSC curve obtained by subjecting the synthetic resin film to differential scanning calorimetry from 25° C. to 250° C. at a heating temperature of 5° C. / min, at least two melting peaks P1 and P2 are observed; The freshness-preserving packaging container for fruits and vegetables, wherein the absolute value of the difference between T1 and T2 is 3 to 40°C, where T1 is the peak top temperature of the melting peak P1 and T2 is the peak top temperature of the melting peak P2. 2. 1. A freshness-preserving packaging container for fruits and vegetables according to claim 1, A freshness-preserving packaging container for fruits and vegetables, in which the lower height of peak P1 and the higher height of peak P2, when taken as a linear baseline of the DSC curve, is H1 and H2, respectively, is a value of H1 / H2 of 0.3 to 0.9. 3. A freshness-preserving packaging container for fruits and vegetables according to 1. or 2. A freshness-preserving packaging container for fruits and vegetables, in which Tmax / Tmin is 1.05 or more, where Tmax is the maximum thickness of the resin film in a region within 10 mm from the outer periphery of the through hole and Tmin is the minimum thickness. 4. A freshness-preserving packaging container for fruits and vegetables according to any one of 1. to 3., The synthetic resin film is a freshness-preserving packaging container for fruits and vegetables having a plurality of through holes. 5. A freshness-preserving packaging container for fruits and vegetables according to any one of 1. to 4., The synthetic resin film is a freshness-preserving packaging container for fruits and vegetables having 30 or less through holes. 6. A freshness-preserving packaging container for fruits and vegetables according to any one of 1. to 5., The freshness-preserving packaging container for fruits and vegetables, wherein the through-holes have a diameter of 30 to 500 μm. 7. A freshness-preserving packaging container for fruits and vegetables according to any one of 1. to 6., The first resin and the second resin are at least one selected from the group consisting of polyethylene, ethylene copolymer, homopolypropylene, random copolymer of propylene, polyvinyl chloride, polystyrene, (meth)acrylic resin, polyester resin and polyamide resin. 8. A package containing fruits and vegetables, the fruits and vegetables being sealed in a freshness-preserving packaging container for fruits and vegetables described in any one of 1. to 7. 9. A method for preserving the freshness of fruits and vegetables, comprising packaging the fruits and vegetables using the freshness-preserving packaging container for fruits and vegetables described in any one of 1. to 7. EXAMPLES

[0091] The embodiments of the present invention will be described in detail based on examples and comparative examples. However, the present invention is not limited to the examples.

[0092] <Production of synthetic resin film (other than Comparative Example 1)> First, the "first layer material" and "second layer material" shown in Table 1 below were prepared. These two materials were co-extruded using a T-die (multi-die) at a temperature of 230° C. The thickness ratio of the two layers at this time was as shown in Table 1 below. The resin extruded from the T-die was cooled and solidified, and then successively stretched 5 times in the machine direction and 9 times in the width direction. In this way, a synthetic resin film was obtained.

[0093] <Production of Synthetic Resin Film (Comparative Example 1)> A synthetic resin film was obtained in the same manner as above, except that a single layer of homopolypropylene was extruded instead of coextrusion.

[0094] <Drilling> A rotating support roll was prepared, which had a diameter of 318 mm and a width of 725 mm and had five grooves, each 5 mm wide and 5 mm deep, spaced 100 mm apart from each other starting at 150 mm from both ends, as shown in Figure 3. A carbon dioxide gas laser with a maximum output of 150 watts was prepared as the laser irradiation device. Each of the five laser irradiation devices was installed so that the laser irradiation position corresponded to the position of the groove in the rotating support roll. The laser irradiation devices were installed so that the distance from the synthetic resin film was 10 to 15 mm. The focal point of the laser was set at a position slightly outside the film from the surface opposite the laser incident surface of the synthetic resin film.

[0095] Next, using the apparatus shown in Figures 1 and 2, the rotating support roll was rotated at a peripheral speed of 60 m / min, and the film was run on the rotating support roll at a constant running speed, and pulse laser was irradiated from each laser irradiation device at regular intervals. At this time, the compressed gas introduction path was supplied with a pressure of 1.0 kg / cm. 2 Nitrogen gas pressure of (gauge pressure) was applied, and during laser irradiation, the nitrogen gas was sprayed from the nozzle tip along the laser beam. The interval between pulsed laser irradiations was appropriately adjusted so that the final number of holes per packaging container would be approximately 20.

[0096] <Manufacturing of packaging containers> First, two of each perforated synthetic resin film were stacked together. Then, the three sides (both sides and the bottom) were heat-sealed using an impulse sealer. The impulse sealer used was Fuji Impulse's FI-400Y-10PK. The heat-sealing process was carried out at 160°C for a sealing time of 1 second, forming a heat-sealed area 10 mm wide. As a result, a roughly rectangular bag-shaped packaging container was obtained. The bag size (outer dimensions) of the obtained packaging container was 140×210 mm. In the packaging containers of the examples, care was taken to ensure that the melting point of the layer on the inner surface side was lower than that of the layer on the outer surface side, making heat sealing easier.

[0097] <Differential scanning calorimetry> First, a part (a part without holes) of the synthetic resin film constituting the packaging container obtained above was cut out to prepare a measurement sample. The measurement sample was set in a differential scanning calorimeter (product number: DSC6220) manufactured by SII Corporation, and measurement was performed under the following heating conditions: 5° C. / min, 25 to 250° C., to obtain a DSC curve. Data analysis (identification of peak top temperatures, setting of baseline, etc.) was performed using SII software provided with the device. From the above, the peak top temperature of the melting peak, the height of the peak relative to the baseline, etc. were determined. 1 and T2 The absolute value of the difference between H 1 / H 2 The value of was calculated. For reference, FIG. 4 shows a DSC curve obtained by measuring a part of the synthetic resin film constituting the packaging container of Example 2 (FIG. 4 shows not only the DSC curve but also the DDSC curve (the derivative of the DSC curve)).

[0098] <Hole properties> T max / T min The maximum thickness T of the synthetic resin film in the area within 10 mm from the outer circumference of the hole max and the minimum thickness T min The thickness of the film was measured according to the mechanical scanning method (Method A) of JIS K 7130. Specifically, the thickness of the film at multiple points arbitrarily selected in the area around the hole (area within 10 mm from the outer circumference of the hole) was measured according to the mechanical scanning method (Method A) of JIS K 7130. The maximum value of the multiple measurement results for the film thickness obtained was designated as T max , the minimum value is T min It was decided.

[0099] Hole diameter The pores were observed under an optical microscope and the pore diameter was measured. In addition, in each of the Examples and Comparative Examples, the diameters of the multiple holes provided in the packaging containers were uniform, approximately 100 μm.

[0100] <Performance evaluation> First, the edamame were washed and dehydrated. 200 g of the edamame were placed in each of the packaging containers prepared above, and the opening of the packaging container was sealed by heat sealing to obtain a package containing fruits and vegetables. The obtained packages containing fruits and vegetables were subjected to temperature changes simulating conditions such as pre-cooling, transportation, fruit and vegetable markets, store backyards, store displays, etc. Specifically, the temperature was changed in the following order (1) to (5). (1) 7℃, 24 hours (assuming pre-cooling) (2) 15°C, 6 hours (assuming transportation) (3) 30°C, 12 hours (assuming room temperature storage in a produce market) (4) 15°C, 6 hours (assuming a store back yard) (5) 25°C, 48 hours (assuming display in a store) Then, the discoloration and taste of the pods of the edamame after (5) (hereinafter also referred to as "evaluation edamame") were evaluated as follows.

[0101] - Evaluation of pod discoloration The evaluation edamame was visually compared with fresh edamame prepared separately. The case where no discoloration was observed was rated as ◯ (good), and the case where discoloration was observed was rated as × (bad). The evaluation was carried out by 10 panelists. In Table 1, items that were marked with an O by 6 or more out of 10 panelists are marked with an X, and items that were not marked with an O are marked with an X.

[0102] Taste evaluation 100 g of the edamame for evaluation was cooked by heating for 2 minutes in a 600 W microwave oven. In addition, 100 g of fresh edamame prepared separately was cooked in the same manner. The taste of these was evaluated by 10 panelists. If the soybeans tasted sufficiently delicious compared to fresh edamame, they were rated as ○ (good), and if they tasted bad compared to fresh edamame, they were rated as × (bad). In Table 1, items that were marked with a circle by more than 6 out of 10 people are marked with a circle, and items that were not marked with a circle are marked with an ×.

[0103] The table below summarizes various information and evaluation results regarding packaging containers. In the table below, the unit of total thickness is μm, T 1 and T 2 The absolute value of the difference is in °C.

[0104] [Table 1]

[0105] The abbreviations for the materials in Table 1 are as follows. The difference in melting point between hPP and rPP was 10°C or more. ·hPP: homopolypropylene material made by Japan Polypropylene Corporation, product number: FB3B rPP: Random polypropylene material (copolymer with ethylene) manufactured by Prime Polymer, product number: WFW5T LLDPE (comparison example): Linear low-density polyethylene material manufactured by Ube Maruzen Polyethylene Co., Ltd., product number: 1540F

[0106] From Examples 1 to 3 in Table 1, it can be seen that when fruits and vegetables are packaged using the fruit and vegetable freshness-preserving packaging container of this embodiment, the freshness of the fruits and vegetables can be well preserved even in environments with various temperature changes.

[0107] On the other hand, the evaluation results of Comparative Examples 1 and 2 were worse than the evaluation results of Examples 1-3. The reason for the poor evaluation result of Comparative Example 1 is thought to be that the film had a single layer structure, and therefore the holes did not expand or contract properly under sudden / irregular temperature changes, and an appropriate amount of outside air could not be taken in / inside air could not be exhausted. The reason why the evaluation result of Comparative Example 2 was poor was that T 1 and T 2 The absolute value of the difference between the temperature and the crystal orientation of the first and second resin layers was over 40°C. This suggests that the crystal orientation of the first and second resin layers was too different, which resulted in the pores not expanding or contracting properly under the sudden / irregular temperature change, and the effect of averaging out the change in pore opening due to temperature change was not achieved. [Explanation of symbols]

[0108] 11 Unwinding roll 12 Synthetic resin film 13 Laser irradiation device 14 Rotating support roll 15 rolls 16 Guide Roll 17 Floating Roll 18 Compressed gas inlet 19 Nozzle tip 20 Pulsed Laser 21 Light guide 22 Output optical unit (lens) 23 Cone Beam 24 holes 25 groove

Claims

1. A method for producing a freshness-preserving packaging container for fruits and vegetables made of a synthetic resin film having through holes, comprising: The present invention comprises at least a first layer and a second layer, and a first resin contained in the first layer and a second resin contained in the second layer have a common structural unit, and in a DSC curve obtained by differential scanning calorimetry from 25° C. to 250° C. at a heating temperature of 5° C. / min, at least two melting peaks P １ and P ２ is observed, and the melting peak P １ The peak top temperature is T １ The melting peak P ２ The peak top temperature is T ２ Then, T １ and T ２ a preparation step of preparing a synthetic resin film having an absolute value of 3 to 40° C. a perforation step of forming through holes in the synthetic resin film prepared in the preparation step to form a perforated synthetic resin film; A step of forming the perforated synthetic resin film obtained in the perforation step into a packaging container; A method for producing a freshness-preserving packaging container for fruits and vegetables, comprising the steps of: (a) forming a container for packaging fruits and vegetables so as to keep them fresh; and (b) forming a container for packaging fruits and vegetables so as to keep them fresh; and (c) forming a container for packaging fruits and vegetables so as to keep them fresh.

2. A method for producing the freshness-preserving packaging container for fruits and vegetables according to claim 1, The peak P １ and the peak P ２ The lower height of the linear baseline of the DSC curve is defined as H １ , the higher height is H ２ Then, H １ / H ２ The method for producing a freshness-preserving packaging container for fruits and vegetables, wherein the value of is 0.3 to 0.

9.

3. A method for producing a freshness-preserving packaging container for fruits and vegetables according to claim 1 or 2, The maximum thickness of the resin film in a region within 10 mm from the outer periphery of the through hole is T ｍａｘ , the minimum thickness is T ｍｉｎ Then, T ｍａｘ / T ｍｉｎ A method for producing a freshness-preserving packaging container for fruits and vegetables, in which the freshness-preserving property is 1.05 or more.

4. A method for producing a freshness-preserving packaging container for fruits and vegetables according to any one of claims 1 to 3, The synthetic resin film has a plurality of through holes, and the method for producing the freshness-preserving packaging container for fruits and vegetables is thus described.

5. A method for producing a freshness-preserving packaging container for fruits and vegetables according to any one of claims 1 to 4, The synthetic resin film has 30 or less through holes.

6. A method for producing a freshness-preserving packaging container for fruits and vegetables according to any one of claims 1 to 5, The method for producing a freshness-preserving packaging container for fruits and vegetables, wherein the through-hole has a diameter of 30 to 500 μm.

7. A method for producing a freshness-preserving packaging container for fruits and vegetables according to any one of claims 1 to 6, The method for manufacturing a freshness-preserving packaging container for fruits and vegetables is characterized in that the first resin and the second resin are at least one selected from the group consisting of polyethylene, ethylene copolymer, homopolypropylene, random copolymer of propylene, polyvinyl chloride, polystyrene, (meth)acrylic resin, polyester resin and polyamide resin.

8. A method for producing a freshness-preserving packaging container for fruits and vegetables according to any one of claims 1 to 7, The method for manufacturing a freshness-preserving packaging container for fruits and vegetables, wherein the perforation step is performed using a laser.

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