JP3230853B2 - Fruit and Vegetable Freshness Packaging Film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for preserving freshness for suppressing the deterioration of freshness of fruits and vegetables such as flowers, fruits and vegetables. More specifically, the present invention relates to a freshness-keeping film for hermetically packaging fruits and vegetables and properly maintaining a gas composition in the system.

[0002]

2. Description of the Related Art As one of the methods for suppressing a decrease in freshness of fruits and vegetables, a method of changing an atmosphere environmental gas composition of fruits and vegetables is generally performed, and CA (Controlled Atomospher) is used.
e) It is put into practical use for long-term storage of apples. In addition, so-called MA (Modified Atmosphere) storage, in which the inside of a package is kept at a low oxygen and high carbon dioxide concentration by utilizing the sealed action of a film and the respiration of fruits and vegetables, is widely used.
At this time, in order to keep the inside of the packaging bag with an appropriate gas composition, it is indispensable to select a film having appropriate oxygen and carbon dioxide gas permeability according to the respiratory volume of the fruits and vegetables.

Conventionally, there are the following three methods for controlling the oxygen and carbon dioxide gas permeability of a film. Selection of film material with appropriate gas permeability Adjustment of gas permeability by changing film thickness Adjustment of gas permeability by opening holes in film uses specific oxygen and carbon dioxide gas permeability depending on the film material, Oxygen, to select the carbon dioxide gas permeability, for example, in the case of polyethylene, which is the most typical thermoplastic resin, the oxygen permeability at 23 ° C. with a thickness of 30μ
For 5000~8000cc / m is ² · 24hrs · atm, also in the case of biaxially oriented polypropylene film of the same thickness oxygen permeability at 23 ° C. is ^{1000~3000cc / m 2 · 24hrs · atm} , film The oxygen and carbon dioxide permeability can be controlled by changing the material.

Utilizing the fact that the gas permeability of a film is inversely proportional to its thickness, it is possible to obtain a wide range of gas permeability by changing the film thickness even for films of the same material. Is a technique in which fine holes are formed in a film and gas permeability is controlled by the size and number of the holes. Film having pores with an average diameter of 20～100Myu, with a 10 to 1000 holes per square meter, 25 ° C., the oxygen permeability at 75% 200000cc / m ² · 24h
A film that can be controlled at rs · atm or less is disclosed in
And Japanese Patent Application Laid-Open No. 2-85181.

[0005]

However, the above-mentioned prior arts have the disadvantage that the material and thickness of the film to be used are limited, and the printability, waist, strength, and sealability of the film material conventionally possessed. At present, it is not practical because the properties and the like are very limited. Furthermore, in the above methods and methods, in the case of a laminated film, the range of choice of oxygen permeability is further reduced. In general, the gas permeability suitable for MA packaging of fruits and vegetables generally ranges from 1,000 to 100,000 cc / m ² · 24 hrs · atm in oxygen permeability at 23 ° C. In contrast, ordinary laminated films often use relatively low-oxygen-permeability packaging materials such as stretched polypropylene, polyamide, and polyethylene terephthalate as a base material. / m ² · 24hrs · atm or less, and not suitable for MA packaging film of fruits and vegetables.

[0006] In the case of fruits and vegetables having a very large respiration rate, such as fruits and vegetables such as green plum, broccoli, and mushrooms, if the oxygen permeability of the film is insufficient, the oxygen concentration in the packaging bag rapidly decreases. Breathing disorder
The product loses its merchantability due to obstacles. In this case, the film
23 oxygen permeability at ℃ usually 15000cc / m ² · 24hrs · atm
Although it may be necessary above, it is difficult to obtain this oxygen permeability by the above method and the above method, and even at a temperature of 23 ° C., even an ethylene / vinyl acetate copolymer film or a polybutadiene film which is a film material having a relatively high oxygen permeability is used. the oxygen permeability also in terms of thickness 30μ 15000cc / m ² · 24hrs ·
Atm or less, there is a danger of respiratory failure due to lack of oxygen in the packaging bag during high temperature distribution in summer.

On the other hand, the technique is basically a method applicable to all kinds of packaging materials, and is far superior to the technique in that the material of the film, the configuration, the presence or absence of printing, and the like are not selected. Is clear. However, in the methods proposed in JP-A-2-783831 and JP-A-2-85181, the average diameter is 20 to 100 μm. With this pore size, when the fruits and vegetables are put in and sealed, minute dust coming out of the fruits and vegetables tends to block the pores, and it is difficult to accurately control the oxygen and carbon dioxide gas permeability. Also, various fine dusts such as dust and film pieces are generated during the opening process, but these also block the hole portions and make it difficult to accurately control the oxygen and carbon dioxide gas permeability.

In addition, when the pore size is 100 μm or less, when printing is performed after opening, the fine pores are filled with printing ink,
It also has the disadvantage of not exhibiting its effect. Opening is not always performed after laminating and printing.If printing, anti-fog processing, etc. are performed after opening, holes with a diameter of 100 μ or less are filled and the hole diameter changes, and oxygen and carbon dioxide It is not possible to precisely control the gas permeability. Further, the current technology has a drawback that optical means such as a laser has to be used for a uniform opening having an average diameter of 100 μm or less, and processing is costly. In the case of a physical method, for example, in the case of opening with a heating needle, it is difficult to control the hole diameter to 100 μm or less, but it is advantageous in cost.

[0009] Further, such fruits and vegetables having a large respiratory rate also generate a large amount of water vapor at the same time. In this case, if the package is sealed by film packaging in order to perform MA packaging, the inside of the packaging bag becomes excessively moist, and forms dew condensation and water droplets and adheres to the inside of the packaging bag. This surplus moisture becomes a hotbed of mold and decay, and causes a decrease in freshness. Even when the above-mentioned micropores are formed, the permeability of oxygen and carbon dioxide can be controlled, but it is difficult to control the water vapor permeability at the same time, and the water vapor permeability of the film depends on the film material itself. It has been clarified by the experiments of the present inventors that the dependence is almost on.

[0010] Therefore, in order to prevent this excessive humidity, it is necessary to use a film material having an appropriate water vapor permeability, but it is usually used in a film of polyethylene, polypropylene or the like used for ordinary fruit and vegetable packaging. At a thickness of about 30μ, its water vapor permeability is 40 ° C, 90
% RH at or less 30g / m ² · 24hrs, fungi due to excessive humidity,
The progress of rot is inevitable. To increase the water vapor transmission rate, there are films that control the water vapor transmission rate by opening a large number of holes with a diameter of 0.5 mm or more. However, this film cannot control oxygen and carbon dioxide gas. In addition, it cannot be used as a film for MA packaging.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to provide a freshness-keeping packaging film for hermetically packing fruits and vegetables and maintaining an appropriate gas composition in the system.

[0012]

The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art, and as a result, if the average diameter of the micropores is 100 to 300 μm, the micropore area and the micropore size are small. Oxygen and carbon dioxide permeability of the film can be controlled by the number of holes, and a film for freshness keeping packaging of fruits and vegetables can be created in which fine pores are not blocked by fine dust from fruits and vegetables and fine dust generated at opening. Further, by selecting a film material having an appropriate water vapor permeability, it has been found that it is possible to suppress the progress of mold and decay and to maintain freshness over a long period of time, and to provide the present invention. It was completed.

Hereinafter, the present invention will be described in more detail. The film for keeping freshness of fruits and vegetables of the present invention has micropores having an average diameter of 100 to 300 µ in the film. The oxygen and carbon dioxide permeability of the film depends on the pore diameter and the number thereof, that is, the pore area.According to the experiments of the present inventors, the oxygen and carbon dioxide permeability per pore is 100 to 900 cc / 24 hrs. atm. This means that the permeation amounts of oxygen and carbon dioxide gas from the micropores are the same, and the permeation amount is proportional to the pore area. For example, when the micropore diameter is 100 μm, experiments by the present inventors have revealed that the oxygen and carbon dioxide gas permeability per micropore is about 100 cc / 24 hrs · atm. Therefore, it is possible to control the oxygen permeability of the film by changing the number of holes per square meter.

In the present invention, the average diameter of the micropores is important. If the average diameter is 300 μm or more, the oxygen and carbon dioxide gas permeability per micropore becomes 900 cc / 24 hrs · atm or more, and the film is suitable for MA storage of fruits and vegetables. It is difficult to control the oxygen and carbon dioxide gas permeability. Further, when the size is 100 μm or less, as described above, when the fruits and vegetables are put in and sealed, minute dust coming out of the fruits and vegetables can easily block the pores, and it is difficult to accurately control the oxygen and carbon dioxide gas permeability. Also, various fine dusts such as dust and film pieces are generated during the opening process, but these also block the hole portions and make it difficult to accurately control the oxygen and carbon dioxide gas permeability.

When the pore size is 100 μm or less, when printing is performed after the opening, the fine pores are filled with printing ink,
It also has the disadvantage of not exhibiting its effect. Opening is not always performed after lamination and printing.If printing or anti-fog processing is performed after opening, holes with a diameter of 100 μ or less will be filled and the hole diameter will change, and oxygen and carbon dioxide will not be formed. It is not possible to precisely control the gas permeability. Further, the current technology has a drawback that optical means such as a laser must be used for a uniform opening having an average diameter of 100 μm or less, and the processing becomes expensive. In the case of a physical method, for example, in the case of opening with a heating needle, it is difficult to control the hole diameter to 100 μm or less, but it is advantageous in terms of cost. For this reason, in the present invention, the average diameter of the micropores is 100 to 300.
μ is an essential element.

In the present invention, the shape of the hole is a circle or an ellipse depending on the processing method and the processing speed. In particular, when a physical method such as a heating needle is used, the contact time between the needle and the film is prolonged, so that the shape tends to be elliptical.
Even in such a case, the average diameter of the holes is 100-300μ.
The same effect can be obtained as long as it has the same area as the circle. That is, in the present invention, the fine holes do not necessarily have to be a perfect circle.

As the material of the film, all the commonly used polymer films can be used, and a laminated film can also be used, and the present invention is not limited by the film material. If the innermost layer has a layer that can be heat-sealed at a low temperature, it is more preferable because sealing and sealing can be easily performed, but if sealing is complete, a method such as rubber band stopper may be used. Further, the film of the present invention is not necessarily required to be transparent, and may be subjected to printing, anti-fogging treatment, etc., if necessary. The opening can be made before or after steps such as printing and anti-fog treatment.

As a method of opening, any of a physical means such as a heating needle and an optical means such as a laser can be used. A pore diameter of 100 to 300 μ is within a range that can be sufficiently opened even by using physical means, and is advantageous in terms of cost. Of course, it can be processed even by a laser or the like, and in this case, the hole diameter can be controlled more precisely.
In addition, when a laser is used for opening the fine holes, the target film needs to efficiently absorb the laser. For example, when processing is performed using a CO ₂ laser, an oscillation wavelength of 10.6 μm is required.
A polystyrene film having a high absorptance in μ is more suitable for micropore opening, and can efficiently perform micropore opening with a lower output laser.

In the present invention, the film material is further limited in the case where the target fruits and vegetables have a large respiratory volume and excessive moisture is generated by hermetically sealed packaging to easily cause mold and rot. For example, broccoli, green plum, mushrooms, etc. It is necessary to select the water vapor permeability. Moderate water vapor transmission rate required for these freshness retention ^{40 ℃, 30~300g / m 2 ·} 24h at 90% RH
rs, more preferably 50 to 200 g / m ² · 24 hrs. If the water vapor permeability is 30 g or less, the progress of mold and spoilage due to excess moisture is rapid. On the other hand, if it is 300 g or more, wiping and weight loss due to transpiration are remarkable, and the marketability is reduced.

Experiments such as those of the present invention have shown that such water vapor permeability cannot be expected from the above-described opened microporous portion. Therefore, for the water vapor permeability, the permeability of the film material itself is used. is necessary. Polystyrene, polybutadiene, polyamide, polyvinyl alcohol, polyvinyl chloride, polymethylpentene, regenerated cellulose, and the like can be used as the film that satisfies the above-described range of the water vapor permeability. It is also possible to use.

With the film for keeping freshness of fruits and vegetables of the present invention, the oxygen and carbon dioxide gas permeability can be controlled by a single film of any material and a laminated film thereof, and the MA for storing fruits and vegetables in a state of low oxygen and high carbon dioxide gas. Storage becomes possible. Further, by selecting the water vapor permeability according to the film material, it is possible to promote appropriate transpiration from the film and suppress the occurrence of mold and rot due to excess moisture. Further, the film used in the present invention is:
As described above, either a single layer or a multilayer may be used. Examples of the multilayer include polyamide / unstretched polystyrene, polyamide / polybutadiene, biaxially stretched polystyrene, polyvinyl alcohol / unstretched polystyrene, and polypinyl alcohol / polybutadiene.

[0022]

Next, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited thereto. Example 1 A single-sided heat-sealable biaxially stretched polypropylene film 30 μm (manufactured by Tokyo Cellophane Paper Co., Ltd.) was continuously used with a heating needle so that the average diameter of the holes was 150 μm and the number of holes was 50 / m ^2. The hole was opened.

Example 2 Biaxially stretched polypropylene film 30μ capable of heat sealing on one side (Tokyo Cellophane Paper)
(Manufactured by Co., Ltd.) were continuously opened using a heating needle so that the average diameter of the holes was 150 μm and the number of holes was 100 / m ² . Example 3 One-sided heat-sealable biaxially stretched polypropylene film 30 μm (manufactured by Tokyo Cellophane Paper Co., Ltd.) was continuously heated using a heating needle so that the average diameter of the holes was 150 μm and the number of holes was 200 / m ^2. The hole was opened.

Example 4 Biaxially stretched polypropylene film 30μ capable of heat sealing on one side (Tokyo Cellophane Paper)
(Manufactured by Co., Ltd.), the holes were continuously opened using a heating needle so that the average diameter of the holes was 150 μm and the number of holes was 200 / m ^2, and then the holes were printed. (Example 5) A non-stretched polystyrene film 30μ (manufactured by Toko Material Co., Ltd.) was prepared with an average diameter of holes of 150μ and the number of holes of 100 / m.
Holes were continuously opened using a heating needle so as to obtain ² .

Comparative Example 1 A biaxially stretched polypropylene film 30 μm (one side heat-sealable) (manufactured by Tokyo Cellophane Paper Co., Ltd.) having an average pore diameter of 500
The holes were continuously opened using a heating needle so that the number of holes was 50 μm / m ² . Comparative Example 2 One-sided heat-sealable biaxially oriented polypropylene film 30μ (manufactured by Tokyo Cellophane Paper Co., Ltd.) had an average diameter of pores of 50 μm.
μ, the number of holes was continuously opened using a laser so that the number of holes became 250 / m ² .

Comparative Example 3 An average pore diameter of 50 μm was formed on a biaxially oriented polypropylene film 30 μ (manufactured by Tokyo Cellophane Paper Co., Ltd.) capable of heat sealing on one side.
μ, the number of holes was continuously opened using a laser so that the number of holes was 500 / m ² . Comparative Example 4 One-sided heat-sealable biaxially oriented polypropylene film 30μ (manufactured by Tokyo Cellophane Paper Co., Ltd.) had an average pore diameter of 50 μm.
μ, the number of holes was continuously opened using a laser so that the number of holes became 1000 / m ² .

Comparative Example 5 A biaxially stretched polypropylene film 30 μm (one side heat-sealable) (manufactured by Tokyo Cellophane Paper Co., Ltd.) was prepared.
The holes were continuously opened using a laser so that the number of holes was 1000 and the number of holes was 1000 / m ^2, and then the openings were printed. Comparative Example 6 One-sided heat-sealable biaxially oriented polypropylene film 30 μm (manufactured by Tokyo Cellophane Paper Co., Ltd.) was used without opening.

Comparative Example 7 Linear low density polyethylene film (LLDPE) 30μ
(Tocello TUX, manufactured by Tokyo Cellophane Paper Co., Ltd.) The holes were continuously opened using a heating needle so that the average diameter of the holes was 150 μm and the number of holes was 100 / m ² . Test Example 1 The results of measuring the oxygen and carbon dioxide gas permeability at 23 ° C. of the films of Examples 1 to 4 and Comparative Examples 1 to 6 of the present invention are shown in Table 1.

As is clear from Examples 1 to 3, the film of this example has a higher oxygen permeability than the unopened single film, and has no clogging due to dust or the like. The oxygen and carbon dioxide permeability could be freely controlled by changing the number, and the oxygen and carbon dioxide permeability was proportional to the number of pores. In addition, even when printing was performed after the opening, the gas permeability did not change.

On the other hand, in Comparative Example 1, the oxygen and carbon dioxide gas permeability was large because the pore size was too large, and the oxygen and carbon dioxide gas permeability was unsuitable as an MA packaging film. Further, as is apparent from Comparative Examples 2 to 5, when the pore size was 50 μm, the pores were partially closed by dust or dust at the time of drilling, so that the oxygen and carbon dioxide gas permeability was low,
Variations were also growing. No proportional relationship was observed between the number of pores and the oxygen and carbon dioxide permeability. Further, when the printing process was performed, some holes were filled with the printing ink, so that the oxygen and carbon dioxide gas permeability further decreased after printing.

[0031]

[Table 1]

Test Example 2 The film of Example 2 and Comparative Examples 1, 4 and 6 had an inner size of 200
Create a pouch of × 150mm (pouch surface area 0.06m ² ),
After 200 g of Shiitake mushrooms were sealed and stored at 20 ° C. for 5 days, the internal gas composition and the quality change of Shiitake mushrooms were examined. Table 2 shows the results.

As is apparent from Table 2, in this embodiment, the inside of the pouch can be maintained at an optimum oxygen concentration, which is effective for preventing browning and wilting of shiitake mushrooms, and furthermore, offensive odor due to excessively low oxygen. Did not occur. On the other hand, in Comparative Example 1, browning advanced due to the high oxygen concentration.
Further, in the film of Comparative Example 4, the holes were partially covered with dust and small swarf pieces at the time of packaging, and, as in Comparative Example 6, the oxygen concentration was too low, and an unpleasant odor was generated.

[0034]

[Table 2]

Test Example 3 The film of Example 1 and Comparative Examples 1, 4 and 6 had an inner size of 300
Create a pouch of × 400mm (pouch surface area 0.24m ² )
1 kg of cut lettuce was hermetically packaged and stored at 10 ° C. for 3 days, after which the internal gas composition and the quality change of cut lettuce were examined. Table 3 shows the results.

As is apparent from Table 3, in this embodiment, the inside of the pouch can be maintained at the optimum oxygen concentration, which is effective for preventing the cut lettuce from browning and wilting. No off-flavor was generated. On the other hand, in Comparative Example 1, browning advanced due to the high oxygen concentration. Further, in the film of Comparative Example 4, the holes were partially covered with dust and small cut lettuce pieces during packaging.
As in the case of the above, an unpleasant odor was generated because the oxygen concentration was too low.

[0037]

[Table 3]

Test Example 4 The results of measuring the oxygen and water vapor transmission rates of Examples 2 and 5 of the present invention are shown in Table 1. As is evident from Table 4, the film of Example 5 had a M value
It has an appropriate water vapor permeability suitable for the A package, and also has an appropriate oxygen permeability.

[0039]

[Table 4]

Test Example 5 Films of Examples 2 and 5 and Comparative Example 7 were 210 × 300 mm
Make a pouch, seal and pack 1 strain of broccoli, and store at 20 ℃
Table 7 shows the results of examining changes in the internal gas composition and broccoli quality after storage for 7 days. As is clear from Table 5, in the present embodiment, the inside of the pouch can be maintained at the optimum oxygen concentration, and the proper transpiration prevents the generation of mold and rot and extends the freshness holding period. It is possible.

[0041]

[Table 5]

[0042]

As described above, the present invention is constructed as described above, so that it is possible to carry out MA packaging by sealing and packaging of fruits and vegetables with films of any material, and to suppress a decrease in freshness of fruits and vegetables for a long period of time. Very useful in industry. Further, by using a film having an appropriate water vapor permeability, MA packaging of fruits and vegetables with high transpiration becomes possible, and the fineness holding period can be further extended.

Continuation of the front page (56) References JP-A-4-53445 (JP, A) JP-A-63-44837 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A23B 7 / 00-7/148 B65D 65/40

Claims (6)

(57) [Claims] 1. A film having fine pores having an average diameter of 100 to 300 μm and having a water vapor permeability of 30 ° C. at 40 ° C. and 90% RH.
A film for keeping freshness of fruits and vegetables, characterized in that the film has an oxygen and carbon dioxide gas permeability of from 300 g / m ² · 24 hrs and the pore area and the number of pores. 2. The film for keeping fresh fruits and vegetables according to claim 1, wherein the material of the film is any one of polystyrene, polybutadiene, polyamide, polyvinyl alcohol, polyvinyl chloride, polymethylpentene, and regenerated cellulose. 3. The oxygen and carbon dioxide gas permeability at 23 ° C. of the entire film having micropores is 1,000 to 100,000 cc / m ² · 24 h.
The film for preserving freshness of fruits and vegetables according to claim 1 or 2, which is rs · atm. 4. The film for keeping fresh fruits and vegetables according to any one of claims 1 to 3, wherein the permeation rate of oxygen and carbon dioxide gas per micropore is 100 to 900 cc / 24 hrs · atm. 5. The method according to claim 1, wherein the number of micropores is 1 to 1000 / m ^2.
5. The film for preserving freshness of fruits and vegetables according to any one of Items 4 to 4. 6. The film for keeping fresh fruits and vegetables according to any one of claims 1 to 5, wherein an innermost surface of the film is subjected to antifogging treatment.