JP3097551B2 - Packaging material for keeping fruits and vegetables fresh - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material used for preserving freshness of fruits and vegetables, such as vegetables and fruits, which can keep the freshness of the fruits and vegetables for a long period of time. The present invention relates to a holding packaging material.

[0002]

2. Description of the Related Art As a conventional package for maintaining freshness of fruits and vegetables, there is a method of maintaining freshness of fruits and vegetables by adjusting a gas composition in the package. This method utilizes the property that fruits and vegetables are generally kept fresh when placed under a gas composition of lower oxygen and higher carbon dioxide than ordinary air. The gas composition in the package is equilibrated at a certain concentration (partial pressure) from the balance between the consumption of oxygen and the generation of carbon dioxide by the breathing of fruits and vegetables in the package, and the gas permeability of the packaging material by packaging in a hermetically sealed material. In this way, the freshness of the fruits and vegetables is maintained.

By the way, in order to maintain a constant composition of oxygen and carbon dioxide in the package, it is important to set the gas permeability of the packaging material in accordance with the respiration rate of the fruits and vegetables. The degree is determined by the respiratory volume of the fruits and vegetables, the weight of the fruits and vegetables, the surface area of the packaging material, and the target gas composition (equilibrium gas partial pressure). The respiratory volume of fruits and vegetables here is not the respiratory volume in the air at the storage temperature, but the expected respiratory volume in the gas composition in the target packaging. It is 1/3 to 1/2 respiratory volume.
Until now, the present inventors have set the oxygen permeability of the packaging material in the freshness-keeping packaging of fruits and vegetables using the following formula 1 as an equation for setting the gas permeability of the packaging material.

[0004]

(Equation 1) Oxygen permeability of packaging material: cc / m ²・ day ・ atm Ventilation volume of fruits and vegetables: cc / kg ・ day Weight of fruits and vegetables: kg Packaging surface area: m ² Equilibrium oxygen partial pressure in packaging: atm On the other hand, packaging material is required As a method of processing so as to have a high gas permeability, JP-A-4-2499 and 5-38765.
The film has a pore size of several μm by the method described in each gazette
There is a method of forming a large number of penetrating or non-penetrating fine holes of up to several tens μm.

However, with a packaging material having such fine pores (hereinafter referred to as "micropore packaging material"), freshness of fruits and vegetables is maintained by using a packaging material having a gas permeability set by the above equation (1). In such a case, the oxygen partial pressure in the package may become lower than the target equilibrium oxygen partial pressure, and the expected freshness maintaining effect may not be obtained. This is because when fine pores are formed from the inner side of the packaging material, water droplets adhere to the inner surface of the packaging material due to moisture generated by respiration of fruits and vegetables when packaging fruits and vegetables,
This is because the pores are blocked by the attached water droplets, and the gas permeability of the packaging material is reduced.

That is, in the microporous packaging material processed from the inner surface side, the water droplets adhere to the inner surface, so that the oxygen permeability is reduced to 20 to 50% of the case where no water droplets adhere.
Therefore, in the case of using a microporous packaging material, Japanese Patent Laid-Open No. 7-2
As disclosed in Japanese Patent No. 03843, it is necessary to set the oxygen permeability of the packaging material using the following equation 2 instead of the above equation 1.

[0007]

(Equation 2) Oxygen permeability of packaging material: cc / m ² · day · atm Vegetable respiration rate: cc / kg · day Weight of vegetable: kg Surface area of packaging material: m ² Equilibrium oxygen partial pressure in packaging: atm a: Correction coefficient (1.2 On the other hand, in the case of the microporous packaging material processed from the outer surface side, the effect of the attachment of water droplets to the inner surface is small, and the decrease in oxygen permeability due to the attachment of water droplets is at most about 20%.
As shown in Japanese Patent Publication No. 75, it is possible to set the oxygen permeability according to the above formula (1). However, in actuality, in the summer when freshness-retaining packaging materials are particularly required, refrigerated storage under high humidity and ice stuffing are performed, and the outer surface of the packaging material often gets wet. Oxygen permeability decreases as in the case of processing.

[0008] Further, the adhesion of water droplets to the surface of the packaging material lowers the transparency of the packaging material and makes it difficult to see the contents. Therefore, at least the inner surface of the packaging material for fruits and vegetables is required to have antifogging properties. However, when a wrapping material having an antifogging property is used on the inner surface, water droplets are apparently not attached, but a thin film of water is actually formed on the wrapping material surface, and the microporous wrapping material has an antifogging property. Even in the case of the packaging material, the pores are blocked by water, and the above-described decrease in oxygen permeability occurs.

Further, when an antifogging wrapping material is used as the microporous wrapping material, the antifogging agent added to the wrapping material elutes into the fine pores formed in the wrapping material and closes the pores. In addition, the oxygen permeability decreases with time. However, the phenomenon reaches an equilibrium within one week after processing, and the oxygen permeability does not decrease even after a longer time. The oxygen permeability when the equilibrium is reached is 30 to 50% of the oxygen permeability immediately after processing.

Therefore, in a microporous packaging material using an antifogging packaging material, when fruits and vegetables are packaged, both the decrease in oxygen permeability due to elution of the antifoggant and the decrease in oxygen permeability due to adhesion of water are caused. As a result, the oxygen permeability during the packaging of fruits and vegetables is significantly reduced, so that there is a problem that freshness cannot be maintained even if the microporous packaging material is processed in accordance with the optimal oxygen permeability for the fruits and vegetables to be packaged. . Further, the above equation (2)
Even if the effect of water is taken into account by using, the oxygen permeability is reduced by the antifogging agent, so that there is still a problem that freshness cannot be maintained.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems.
The oxygen permeability of the packaging material when actually packaging the fruits and vegetables becomes the oxygen permeability suitable for maintaining the freshness of the fruits and vegetables,
In addition, it is an object of the present invention to provide a packaging material for maintaining freshness of fruits and vegetables, wherein at least the innermost layer is made of a microporous packaging material having antifogging properties.

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that at least the innermost layer is provided with an antifogging agent.
The multilayer film consisting of the heat-fusible resin layer
By Do through or form blind holes innumerable, in Freshness packaging material fruits or vegetables to control the oxygen permeability of the multilayer film, at least the heat-fusible resin layer has an antifogging, In addition, the oxygen permeability of the multilayer film immediately after forming the pores is 3,000 to 30,000 cc, which is necessary for maintaining the freshness of the fruits and vegetables to be packed.
/ M ² · day · atm 5 to 10 times the fine pores having a pore size of several μm to several tens μm in the multilayer film.
A packaging material for maintaining the freshness of fruits and vegetables, characterized in that a through-hole or an unpenetrated hole is formed.

[0013] The invention according to claim 2 is characterized in that the oxygen permeability of the multilayer film immediately after forming the pores is from 15,000 to 15,000.
The packaging material for keeping freshness of fruits and vegetables according to claim 1, characterized in that it is in a range of 300,000 cc / m ² · day · atm.

Further, the invention of claim 3 is characterized in that the multilayer film is a laminated film of a base film and a heat-fusible resin film to which an antifogging agent is added. 2. A packaging material for keeping freshness of fruits and vegetables according to 2.

According to a fourth aspect of the present invention, there is provided the packaging material for maintaining freshness of fruits and vegetables according to the third aspect, wherein the base film is a stretched polypropylene film, a stretched nylon film or a polyethylene terephthalate film. .

The invention according to claim 5 is that the heat-fusible resin film is a film of low-density polyethylene, linear low-density polyethylene, undrawn polypropylene or ethylene-vinyl acetate copolymer resin. The packaging material for keeping freshness of fruits and vegetables according to claim 3, characterized in that:

As described above, the packaging material for keeping the freshness of fruits and vegetables of the present invention has a pore size in a multilayer film in which at least the innermost layer has antifogging properties and at least the innermost layer is a heat-fusible resin layer. By forming an infinite number of micro-perforated or non-perforated holes of several μm to several tens of μm, the oxygen permeability of the packaging material when actually packaging the fruits and vegetables is the oxygen permeability suitable for maintaining the freshness of the fruits and vegetables, 3,000 to 30,00
It is a packaging material processed to be in the range of 0 cc / m ² · day · atm.

That is, the packaging material for keeping freshness of fruits and vegetables of the present invention reduces oxygen permeability due to an antifogging agent and water when forming fine pores in the multilayer film (hereinafter simply referred to as “processing”). In consideration of the above, processing is performed so that the oxygen permeability of the packaging material immediately after processing falls within a range of 5 to 10 times the oxygen permeability required for maintaining the freshness of the fruits and vegetables to be packed. Here, the oxygen permeability required for maintaining the freshness of the fruits and vegetables to be packaged is the optimum oxygen permeability set by the above-described formula 1, and is generally 3,000 to 30,000.
It is in the range of cc / m ² · day · atm.

Therefore, the packaging material for keeping freshness of fruits and vegetables of the present invention has an oxygen permeability of 15,000-30 immediately after processing.
It is in the range of 0.00000 cc / m ² · day · atm.

In a conventional packaging material for maintaining freshness using a microporous packaging material, only the influence of water adhering to the packaging material was considered when setting the oxygen permeability. In order to process the microporous packaging material by setting the oxygen permeability immediately after processing to 5 to 10 times higher than the oxygen permeability required at the time of packaging in consideration of the decrease in oxygen permeability due to When packaged, the oxygen permeability becomes optimal, and the freshness of fruits and vegetables can be maintained by a microporous packaging material using an antifogging packaging material.

[0021]

Embodiments of the present invention will be described below in detail.

Since the packaging material for keeping the freshness of fruits and vegetables of the present invention is used by hermetically sealing and packaging the fruits and vegetables, it is necessary to have heat-sealing property so that sealing by heat-sealing can be performed. In consideration of the above, a packaging material made of a multilayer film is preferable. Therefore, as the configuration of the packaging material that can be used in the present invention, for example, stretched polypropylene,
Base film such as stretched nylon, polyethylene terephthalate, etc., and heat-fusible resin such as low-density polyethylene, linear low-density polyethylene, non-stretched polypropylene, ethylene / vinyl acetate copolymer, etc. The present invention is, of course, not limited thereto, and any structure may be used as long as it is a laminated film of a base film and a heat-fusible resin film containing an anti-fog agent. it can. The number of layers of the laminated film is basically two layers of the base film and the heat-fusible resin film, but each of the base film and the heat-fusible resin film is composed of two or more layers. It may be a configuration. The thickness of the packaging material is determined in consideration of the strength and processing suitability required for the packaging of fruits and vegetables, but is generally 30 to
Those having a thickness of about 50 μm are suitable.

As described above, the packaging material for keeping freshness of fruits and vegetables of the present invention has at least an innermost layer,
That is, although the anti-fogging agent is added to the heat-fusible resin film, the anti-fogging agent may also be included in the base film. Since the contents are fruits and vegetables, the antifogging agent used in the present invention is desirably a material that does not affect the fruits and vegetables at all. Therefore, specific examples of the antifogging agent used in the present invention include, but are not limited to, sorbitan fatty acid esters, fatty acid diethanolamide, diglycerin fatty acid esters, polyoxyethylene glycerin monofatty acid esters, and the like. . The amount of the anti-fogging agent is not particularly limited, but usually, it is sufficient to add an amount necessary for imparting anti-fogging property.

When the above-mentioned laminated film is used as a packaging material, it is necessary to process the film so as to have a necessary oxygen permeability. Specifically, by forming innumerable through-holes or non-penetrating micropores having a pore diameter of several μm to several tens μm from either one side of the laminated film, and controlling the number, depth, and size of the pores A method for obtaining the required oxygen permeability is preferred. Therefore, it is a method of forming a myriad of fine holes in the laminated film. For example, if processing is performed using a method represented by each method described in JP-A-4-2499 and JP-A-5-38765. Good. That is, a method in which fine artificial diamond particles are coated on the surface of a metal roller to form a film, a film is passed between the roller and a roller opposite thereto, and fine holes are formed. In this processing, either processing from the outer layer side (substrate film side) or processing from the inner layer side (heat-fusible resin film side) of the laminated film may be performed. That is, processing may be performed from a surface that is easy to process, depending on the configuration and thickness of the packaging material. At this time, the fine pores to be formed in the laminated film have a pore diameter of several μm.
As long as it is in the range of m to several tens of μm, it may be a through hole, a non-through hole, or a mixture of both, and is not particularly limited in the present invention.
That is, processing may be performed so as to obtain a necessary oxygen permeability. However, when the pore diameter is larger than 100 μm, the pore becomes a complete through-hole and the oxygen permeability becomes extremely high, so that it becomes difficult to control the oxygen permeability in a range suitable for maintaining the freshness of the fruits and vegetables. Not preferred.

As shown in FIG. 1, the laminated film 1 (formed of an outer layer base film 2 and an inner layer heat-fusible resin film 3) which has been opened by the method described in the above publication is In most cases, both through-holes 4 and non-through-holes 5 are formed, the ratio of which is between 0 and 1 depending on the oxygen permeability obtained.
The ratio of the through-holes varies in the range of 00%, and the higher the oxygen permeability, the higher the ratio of the through holes. And the through hole here is
In addition to the complete through hole 4, a case where a crack 7 is formed in the film remaining portion 6 of the non-through hole 5 and both sides of the film are connected is also included.

By the way, the oxygen permeability required for the above-mentioned microporous packaging material can be set by the above formula 1, but the oxygen permeability set by the formula 1 is set at the time of actual packaging of fruits and vegetables. In the case of a microporous packaging material having a required oxygen permeability and having anti-fogging property, the oxygen permeability is significantly lower when using the actual packaging material than immediately after processing due to elution of the anti-fogging agent and adhesion of water. Therefore, in the processing, the processing is performed so that the oxygen permeability becomes higher than the oxygen permeability set by Expression 1 in anticipation of the decrease in the oxygen permeability during use. In practice, considering the decrease due to the anti-fog agent,
Three times, taking into account the decrease due to the adhesion of water,
Process so that the oxygen permeability is up to 4 times. That is,
Together with the reduction due to both the anti-fogging agent and water, the oxygen permeability immediately after processing is such that the oxygen permeability is about 5 to 10 times, preferably 7 to 8 times the oxygen permeability set by Formula 1. It is sufficient to process it.

Incidentally, the oxygen permeability when using the actual packaging material is as follows:
Since the processing state of the packaging material and the state of the fruits and vegetables that are the contents are different, it cannot be predicted accurately in advance, but the oxygen permeability suitable for maintaining the freshness of the fruits and vegetables is the oxygen permeability of the oxygen permeability set by the formula 1 described above. There is not only one point but also a tolerance of about ± 50% around that value. In practice, freshness of fruits and vegetables can be maintained by using a packaging material having an oxygen permeability in that range. Therefore, in the packaging material for maintaining freshness of fruits and vegetables of the present invention, by processing so that the oxygen permeability immediately after processing falls within the range of the above magnification, it is possible to substantially maintain the freshness when the actual fruits and vegetables are packaged. A suitable acceptable range of oxygen permeability results.

Here, the oxygen permeability set by the formula 1 is the oxygen permeability at the storage temperature of fruits and vegetables, but the oxygen permeability of the microporous material according to the present invention is hardly affected by the temperature. The oxygen permeability at the storage temperature does not need to be, and the oxygen permeability at room temperature can be used instead.

The oxygen permeability actually set by the equation (1) is usually 3,0 except for special contents.
Since it is in the range of 00 to 30,000 cc / m ² · day · atm, the oxygen permeability immediately after processing of the microporous packaging material according to the present invention is 15,000 to 300,0, which is 5 to 10 times the same.
The range is 00 cc / m ² · day · atm. Therefore, the packaging material may be processed so as to have such an oxygen permeability range.

The packaging material for maintaining the freshness of fruits and vegetables of the present invention enables the freshness of fruits and vegetables such as vegetables and fruits to be maintained for a long period of time.
It can also be used for freshness preserving packaging such as flowers.

[0031]

EXAMPLES Specific examples of the present invention will be described below.

Example 1 A stretched polypropylene film having a thickness of 20 μm (SS121, manufactured by Honshu Paper Co., Ltd.) and an antifogging type linear low-density polyethylene film having a thickness of 25 μm (manufactured by Tosello Co., Ltd., T
UX TNF) and a laminated film obtained by dry lamination,
Using the method described in the above-mentioned publication, the pore size is several μm to several tens μm.
Countless fine pores are formed, and the oxygen permeability immediately after processing is approximately 20,000, 40,000, 80,000, 1
50,000 and 250,000 cc / m ² · day
-Processing of five types of microporous packaging materials was performed so as to be atm. These packaging materials have oxygen permeability at the time of use of 3,000, 5,000, 10,000, 20,000, respectively.
00 and 30,000 cc / m ² · day · atm.

Next, the oxygen permeability of each packaging material was measured immediately after processing.
Measurements were taken after day and after 7 days. The oxygen permeability is
It was determined as follows. That is, a bag having a surface area of 400 cm ² was prepared for each packaging material, and nitrogen gas 400 c
c was filled and sealed, left at 25 ° C. for 1 to 2 hours, and then determined by measuring the oxygen concentration in the bag. Seven days later, water was sprayed on the inner surface of the bag by spraying, and the oxygen permeability in that state was measured by the same method.

The results obtained are summarized in Table 1 below.

The oxygen permeability of the immediately processed in the same manner on the same laminated film as Example 1 Comparative Example above 10,000 and 400,000c
The microporous packaging material was processed to have c / m ² · day · atm, and the oxygen permeability was measured in the same manner as in Example 1. The results are also shown in Table 1 below.

[0036]

[Table 1] From the results in Table 1, all the packaging materials of the examples of the present invention were within ± 50% of the assumed oxygen permeability (the expected value during use in Table 1) in a state of being wet with water assuming use, Actually ±
It showed an oxygen permeability within 15%. Therefore, it can be seen that each packaging material can be used for maintaining the freshness of fruits and vegetables requiring the assumed oxygen permeability.

On the other hand, in the case of the packaging material of the comparative example, in the case of the packaging material processed so that the oxygen permeability immediately after processing becomes 10,000 cc / m ² · day · atm, the oxygen permeability when wet with water is reduced. 1,400 cc / m ² · day · atm, which shows almost the same oxygen permeability as the unprocessed packaging material, resulting in the same result as not performing the fine hole processing,
Oxygen permeability required for maintaining freshness cannot be obtained. Further, the oxygen permeability immediately after processing is 400,000 cc / m ² · day.
The packaging material processed to atm has an oxygen permeability of 56,000 cc / m ² · day even when wet with water.
Indicates atm, which is 30,000 cc / m ^2, which is the maximum value of the general oxygen permeability required for maintaining the freshness of fruits and vegetables
It is a value of + 50% or more of day.atm and cannot be used as a packaging material for keeping freshness of fruits and vegetables.

Example 2 A biaxially stretched polyethylene terephthalate film having a thickness of 12 μm (Lumilar Q-27 manufactured by Toray Industries, Inc.) and a thickness of 25
μm antifogging type unstretched polypropylene film (FHBK, manufactured by Nimura Chemical Industry Co., Ltd.) is laminated by a dry lamination method, and the obtained laminated film is coated from the polypropylene film side using the method described in the aforementioned publication. The oxygen permeability immediately after processing is about 15,000, 50,000
0, 100,000 and 300,000 cc / m ^2.
Four types of microporous materials were processed so as to be day.atm, and then the oxygen permeability was measured in the same manner as in Example 1 described above.

The results obtained are summarized in Table 2 below.

[0040]

[Table 2] As described above, the oxygen permeability at the time of use is expressed by the equation (1).
Since the freshness of the fruits and vegetables can be maintained within the range of ± 50% of the oxygen permeability required for maintaining the freshness of the fruits and vegetables determined by the above, as shown in Table 2 above, for example, the oxygen permeability immediately after processing is 15, When set to 2,000 cc / m ² · day · atm, finally 2,000 cc / m ² · day
y · atm oxygen permeability, for example, 3,000 c
It can be used to maintain the freshness of fruits and vegetables requiring c / m ² · day · atm oxygen permeability. Further, the oxygen permeability immediately after the processing was 300,000 cc / m ² · day · atm.
When set to 43,000 cc / m ² ·
oxygen permeability of day.atm, for example, 30,0
It can be used to maintain the freshness of fruits and vegetables requiring an oxygen permeability of 00 cc / m ² · day · atm. Further, the oxygen permeability immediately after processing was 50,000 cc / m ² · day ·
atm and 100,000cc / m ² · day · at
m, 6,900c each
c / m ² · day · atm and 11,500 cc / m ²
It can be used for maintaining freshness of fruits and vegetables that require oxygen permeability within the range of 1/5 to 1/10 of the set oxygen permeability.

[0041]

As described above in detail, according to the packaging material for keeping the freshness of fruits and vegetables of the present invention, the packaging material has an anti-fogging property and the oxygen permeability of the packaging material is included in the packaging material. Oxygen suitable for maintaining the freshness of the packaged fruits and vegetables when they decrease due to the effect of the dissolution of the antifogging agent and the adhesion of moisture generated from the fruits and vegetables, that is, when the fruits and vegetables are actually packed. Because of the transparency, as a result, an excellent effect of enabling freshness-preserving packaging capable of maintaining the freshness of fruits and vegetables for a long time is achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a laminated film used as a packaging material of the present invention in a state in which fine holes are formed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laminated film 2 base film 3 heat-fusible resin film 4 through-hole 5 non-through hole 6 film-remaining portion of non-through hole 7 crack

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B32B 27/32 B32B 27/32 Z B65D 65/40 B65D 65/40 81/26 81/26 A (72) Inventor Hiroshi Kida (202) Inventor Koji Takeshita 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Asako Takahashi 1-Taito, Taito-ku, Tokyo 5-5-1 Toppan Printing Co., Ltd. (72) Inventor Kosuke Ishitani 3-19-1, Azuma, Tsukuba-shi, Ibaraki Park Hill 2-402 (72) Inventor Kazunori Sato 4-424-302, Matsushiro, Tsukuba-shi, Ibaraki (56) reference Patent flat 7-203843 (JP, a) JP flat 7-255373 (JP, a) JP flat 5-316943 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) A23B 7/00-7/16

Claims (5)

(57) [Claims] 1. A multi-layer film comprising at least an innermost layer comprising a heat-fusible resin layer to which an anti-fogging agent is added, in which a number of fine through-holes or non-through holes are formed to form a multilayer. In the packaging material for keeping freshness of fruits and vegetables controlling the oxygen permeability of the film, at least the heat-fusible resin layer has antifogging properties, and the oxygen permeability immediately after forming the pores of the multilayer film, Oxygen permeability required to maintain the freshness of the fruits and vegetables to be packed is 3,000 to 30,000 cc / m ² · d
fine penetration with a pore size of several μm to several tens μm in the multilayer film so as to be in the range of 5 to 10 times of
A packaging material for preserving freshness of fruits and vegetables, characterized by forming an unpenetrated hole. 2. The oxygen permeability of the multilayer film immediately after forming pores is 15,000 to 300,000 cc / m.
^{2. The} packaging material for preserving freshness of fruits and vegetables according to claim 1, wherein the packaging material has a range of ² * day * atm. 3. The multilayer film, comprising: a base film;
3. The packaging material for keeping freshness of fruits and vegetables according to claim 1, wherein the packaging material is a laminated film with a heat-fusible resin film to which an antifogging agent is added. 4. The packaging material for keeping freshness of fruits and vegetables according to claim 3, wherein the base film is a stretched polypropylene film, a stretched nylon film or a polyethylene terephthalate film. 5. The heat-fusible resin film is a film of low-density polyethylene, linear low-density polyethylene, unstretched polypropylene, or ethylene-vinyl acetate copolymer resin. Packaging material for keeping fresh fruits and vegetables.