JPH0852841A - Hygroscopic packaging material and freshness-keeping packaging bag using the material - Google Patents

Abstract

PURPOSE:To provide a hygroscopic packaging material which can absorb excessive water content inside as a function of a freshness-keeping packaging material and prevent 'stuffiness' to be generated by the water content included in food without requiring to enclose a special drying agent. CONSTITUTION:Of three layers, an outer layer A is composed of a first synthetic resin film 11, an intermediate layer B is composed of hygroscopic cellophane 12 and an inner layer C is composed of a second synthetic resin film 13. A through-hole 14 is formed on the inner layer film 13 so that a part of the hygroscopic cellophane 12 is brought into contact with atmosphere outside directly, and a constitution for absorbing excessive water content inside and not passing the water content and oxygen from outside is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hygroscopic packaging material suitable as a packaging material for keeping freshness, and a packaging bag for keeping freshness using the hygroscopic packaging material.

[0002]

2. Description of the Related Art Conventionally, it has been customary to wrap a fresh food product in a transparent gas barrier packaging material.
With the widespread distribution and packaging of fresh foods in recent years, the development of new packaging materials for keeping freshness has become more and more important.

Transparent gas barrier packaging materials include plastic films such as polypropylene, polyethylene and polyethylene terephthalate, and oxygen impermeable materials such as cellophane, polyvinyl alcohol, nylon, polyvinylidene chloride and ethylene vinyl acetate copolymer. It is made by laminating films, and when the food is hermetically packaged by this transparent gas barrier packaging material, oxygen and moisture are not permeated and the food can be kept fresh for a long time.

However, when the food is sealed only with the gas barrier packaging material, evaporation and condensation of water due to temperature change cannot be avoided, and there is a risk of mold, lipid oxidation, crushing, and pest generation. Therefore, with respect to this problem, it is known that the effect of enclosing a desiccant, an oxygen scavenger, an antibacterial agent, etc. in the package can further enhance the freshness-retaining effect.

[0005]

However, such a technique has a problem in that such a desiccant, an oxygen scavenger, an antibacterial agent, etc. must be prepared in advance and enclosed in a package. is there.

As a desiccant, silica gel, calcium chloride, etc. are often enclosed together. These desiccants strongly absorb moisture, but their moisture absorption capacity is small. Further, although it is suitable for keeping a small amount of water in an absolutely dry state, it does not have the ability to retain a certain amount of water and absorb moisture appropriately. In addition, antibacterial agents such as alcohol preparations are also used in some foods, but they have problems such as taste.

Further, regarding the technique of enclosing the oxygen scavenger, how to maintain proper water content is a problem in relation to the type of food in the package.

That is, natural agricultural products such as rice, especially cereals, have an equilibrium water content of about 10 to 15 wt%, and when the relative humidity is maintained at about 60 to 80%, there is no crushing and oxidation of lipids,
It has a good taste without mold. Dried sardines, dried bonito flakes,
Dried seafood such as kelp and confectionery such as rice crackers also contain a certain amount of water, and the water may move due to changes in humidity, which causes deterioration such as oxidation of lipids.
Maintaining a constant water vapor pressure in the package is important for maintaining the quality of food. For vegetables and fruits, fruits and vegetables such as fresh flowers, the atmospheric gas is adjusted at the same time as the adjustment of the water content (C, A-Controlled).
Atmosphere) is required, and when stored in low oxygen and high carbon dioxide, overripening is suppressed and freshness lasts longer. Further, if the antibacterial action and the production of plant hormone (eg ethylene gas) can be suppressed, the effect is further enhanced.

On the other hand, with the widespread use of refrigerators at home, fresh foods are often put in plastic bags for storage, and the use of highly sealed bags with fasteners is increasing. If the bag with a fastener can give moisture absorption, an antibacterial property, and a CA action, it will have a great effect as a freshness-keeping bag.

The present invention has been made in view of the above problems, and an object thereof is to prevent the permeation of moisture and oxygen from the outside, but to absorb the excessive moisture in the interior, without enclosing a special desiccant. It is an object of the present invention to provide a hygroscopic packaging material capable of preventing "steaming" caused by the water contained in the food and a packaging bag for keeping freshness using the hygroscopic packaging material.

[0011]

In order to achieve the above object, the first hygroscopic packaging material of the present invention comprises three layers of an outer layer, an intermediate layer and an inner layer, the outer layer being a first synthetic resin film,
The intermediate layer is a hygroscopic cellophane, the inner layer is composed of a second synthetic resin film, and has a through hole in the inner layer film,
A part of the hygroscopic cellophane has a structure in which it directly contacts the atmosphere.

The second hygroscopic wrapping material of the present application comprises three layers of an outer layer, an intermediate layer and an inner layer, the outer layer is a first synthetic resin film, the intermediate layer is a hygroscopic cellophane, and the inner layer is a second layer. It is composed of a synthetic resin film, the outer layer film is a fragrance retaining film, the inner layer film is an antibacterial film, and has a through hole communicating with the inner layer film and the hygroscopic cellophane of the intermediate layer. It is configured.

Preferably, in the hygroscopic packaging material of the present invention, the hygroscopic cellophane in the intermediate layer is ordinary cellophane and its weight is 5%.
% To 20% glycerin.

Also preferably, the hygroscopic packaging material of the present invention is
Through hole of thermoplastic synthetic resin film of inner layer is 0.1m
It has a hole diameter of m to 1.5 mm and an aperture ratio of 5% to 23%.

The freshness-keeping packaging bag of the present invention is obtained by processing the hygroscopic packaging material into an airtight bag with a fastener.

[0016]

In the first hygroscopic packaging material of the present invention, as shown in FIG. 3, external moisture and water vapor 2 are blocked by the synthetic resin film 11 of the outer layer A, and the external oxygen gas absorbs moisture of the intermediate layer B. It is blocked by sex cellophane 12 and does not penetrate inside. Moisture generated from the food inside is absorbed 3 and released 4 by the hygroscopic cellophane 12 through the through holes 14 provided in the inner layer film 13, and the humidity in the system is stabilized. Therefore, this hygroscopic packaging material can be used as a hygroscopic / gas barrier packaging material.

In the second hygroscopic packaging material of the present invention, as shown in FIG. 4, the outer layer A is a fragrance retaining film 21, the intermediate layer B is a hygroscopic cellophane 22, and the inner layer C is an antibacterial film 23. The through hole 24 communicates not only the film 23 of the inner layer C but also the hygroscopic cellophane 22 of the intermediate layer B. Therefore,
Through this through hole 24, a part of the external oxygen gas 1 and a part of the internal carbon dioxide gas 6 permeate through the outer layer A fragrance-retaining film 21 to exert the CA effect and absorb moisture generated from foods. The cellophane 22 controls the moisture absorption 3 and the moisture release 4 to control, and the inner layer antibacterial sheet 23 exhibits an antibacterial action. Therefore, this hygroscopic packaging material can be used as a hygroscopic / antibacterial CA packaging material.

When the hygroscopic cellophane in the intermediate layer is ordinary cellophane and contains 5 to 20% by weight of glycerin, the hygroscopic property, safety (for food use),
Optimal from the perspective of processing characteristics. If the amount of glycerin is 20% or more based on the weight of cellophane, there is a risk that it will exude from cellophane, and the adhesiveness will also deteriorate. If it is 5% or less, the effect is small.

Further, it is preferable that the through hole of the thermoplastic synthetic resin film of the inner layer has a hole diameter of 0.1 mm to 1.5 mm and the aperture ratio is 5% to 23%. Is 1.5 mm or more, there is a risk of electrical connection between the outside and inside of the bag during heat bonding, and if the pore size is smaller than about 0.1 mm, a sufficient opening ratio cannot be obtained. On the other hand, if the opening ratio is too large, the strength of the inner layer may be uncertain and the inside and outside of the bag may be electrically connected when the film is adhered. If it is too small, the moisture permeability may be insufficient. Aperture ratio of 5% to 23%
If so, it does not affect transparency.

The freshness-keeping packaging bag of the present invention is obtained by processing the hygroscopic packaging material into an airtight bag with a fastener, and is suitable as a freshness-keeping packaging bag.

[0021]

[Examples] As a transparent gas barrier multi-layer packaging material used for food packaging, a water-impermeable thermoplastic synthetic resin film (plastic film) is used as an outer layer and an inner layer, and oxygen-blocking cellophane is used as an intermediate layer. A laminate of thin films such as polyvinyl alcohol, ethylene vinyl acetate copolymer, and nylon is often used. Therefore,
If you can make use of the characteristics of the laminated film and realize the required performance such as gas barrier property, humidity control (moisture absorption and moisture release), antibacterial property (bacteriostatic property), and oxygen and carbon gas permeability, A packaging material suitable for each application is possible. It is also necessary to be able to directly apply the bag making machine, the packaging machine, etc. which are widely used at present, and it is desirable that the constituent film is a general-purpose film. This will be examined below.

<Gas Permeability> The gas permeability of the laminated film is determined by the gas permeability of the constituent films.

[0023]

[Equation 1] α = gas permeability of laminated film α 1 to α n = gas permeability of each constituent film For example, polypropylene, polyethylene (CCP) / PT
Table 1 shows the oxygen gas permeability and the water vapor permeability of the laminated film of cellophane / low density polyethylene (L-LDPE).

[0024]

[Table 1] By laminating as shown in Table 1, the features of each film can be utilized to make an inexpensive and high-performance packaging material.

<Moisture Control (Moisture Absorption and Moisture Release)> Generally, the laminated film has excellent water permeation resistance, oxygen permeation resistance, printability, and sealability and has very good characteristics, but since it has no hygroscopicity, Due to the water content of the food inside, it easily “steams”.

The hygroscopic packaging material of the present invention does not permeate moisture and oxygen from the outside, but absorbs excess moisture inside, and can prevent "steaming" without enclosing a special desiccant. . Further, when the humidity is lowered, it has a characteristic of releasing moisture, so that it has a humidity adjusting function for keeping the inside of the system at a constant humidity.

<Antibacterial property> For the inner layer film in contact with food,
When a film prepared by kneading an antibacterial agent such as hinokitiol having an antibacterial effect or silver apatite is used, the effect of maintaining the freshness of food can be exhibited.

The hygroscopic packaging material processing method of the present invention can also be used as it is in a conventional printing machine or packaging machine.

<Hygroscopicity of Intermediate Layer> The film of cellophane, ethylene vinyl acetate copolymer, polyvinyl alcohol, nylon, etc. used for a part of the gas barrier layer (intermediate layer) has hygroscopicity, If moisture can be absorbed through the film, "stuffy" inside the bag can be prevented.

Among these, cellophane has a high hygroscopic property, and particularly when a softening agent such as glycerin, sorbitol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol or polyethylene glycol is added, the hygroscopic property is further improved.

As a hygroscopic packaging material suitable for the present invention, a combination of ordinary cellophane and glycerin is most suitable in terms of hygroscopicity, safety (for food use), processing characteristics and the like. Glycerin has high moisture absorption and desorption properties, and its vapor pressure changes depending on the water content. The relationship between relative humidity (RH) and glycerin concentration is shown in FIG.

As cellophane, PT-300, PT-3
50, PT-400, PT-500, PT-600, etc. can be used and the moisture absorption is proportional to the amount of glycerin, so the cellophane count (thickness) and glycerin amount within the range that does not bleed (exude) from cellophane You have to choose.
From 20% glycerin content of PT-600, PT-30
Glycerin of 0 to 5% may be selected according to the desired moisture absorption amount. Glycerin is 20% by weight of cellophane
If it is more than 100%, it may exude from cellophane, and the adhesiveness may deteriorate. If it is 5% or less, the effect is small. Also, it is necessary to note that cellophane usually increases oxygen permeability when the relative humidity is 90% or more.

<Moisture Permeability of Inner Layer Film> The inner layer film can be made to be moisture permeable by allowing pores to penetrate through the entire surface of the film. As for the pores, the maximum diameter is about 1.5 mm because the bag is formed by heat bonding and the width of the heat plate for heat bonding is about 2 mm at the minimum. Sometimes the inside and outside of the bag may become conductive). Further, if the pore size is small, a sufficient aperture ratio cannot be obtained, so about 0.1 mm is the minimum. If the opening ratio is too large, the strength of the inner layer is uncertain, and the inside and outside of the bag may be electrically connected when the film is adhered. If it is too small, the moisture permeability is insufficient.

At the time of heat sealing, it is important to apply pressure using a narrow heating plate and completely melt and bond the sealing surface so that the influence of the pores of the inner layer film does not affect the sealing strength.

As shown in FIG. 2, the aperture ratio of the aperture film is determined by its arrangement, the hole diameter 2r, and the distance d between the holes.

In the equilateral triangle arrangement,

[Equation 2] In a square arrangement

(Equation 3) n = number of holes r = radius of holes d = interval of holes and holes When bag-making with the film of the present invention, conduction inside and outside the bag is not allowed, and therefore d> 2r is required, and aperture ratio is 23 even in triangular arrangement. % Is the limit. However, this is not the case when the packaging material of the present invention is used only in a part of the bag and there is no influence of the opening in the sealing portion.

From the viewpoint of moisture permeability, the lower limit of the aperture ratio is 5
%. Pore diameter 0.1mm-1.5mm, aperture ratio 5
When it is -23%, it has almost no effect on the transparency, so there is no problem in producing a transparent multilayer film.

FIG. 2 shows the relationship between the hole diameter and spacing and the aperture ratio. It is advisable to determine the arrangement of holes, the diameter of the holes, and the spacing so that the desired aperture ratio is obtained.

<Making the inner layer film antibacterial> In order to make the inner layer plastic film antibacterial, it is preferable to use a plastic film in which an antibacterial agent is kneaded in advance. A plastic film containing a hinokitiol-containing material clathrated in cyclodextrin as a volatile antibacterial agent (JP-A-3-167261, JP-A-4-325069, etc.)
As a contact antibacterial agent, pellets obtained by mixing and molding metal silver ceramic antibacterial agents (Sangi Co., Ltd., Apacider A etc.) as polyethylene as apatite are commercially available as master batches, and are mixed with plastic raw materials. However, the antibacterial film can be easily produced by the T-die extrusion method, the inflation method, or the like.

In the case of hinokitiol and its salts, the content of the antibacterial agent is 10 mg / m ² to 100 mg /
m ² is suitable. 0.2% as silver apatite
To 2% (by weight) is suitable. Inorganic substances such as silver apatite cannot be mixed in a large amount because the transparency deteriorates.

Hinokitiol and its salts also have the effect of suppressing the physiological activity of plants, and can be expected to have the ability to suppress the production of ethylene, which is a growth hormone of plants, and to make fruits and vegetables last longer. When used in combination with CA film, the effect is doubled.

<Adhesive and Others> Since the hygroscopic cellophane used for the intermediate layer cannot be heat-bonded, an adhesive must be used. As an adhesive, it is convenient to preliminarily co-extrude a polyolefin-based adhesive film (registered trademark “Adtex”, Showa Denko KK, etc.) on one side during extrusion molding of the film for the outer and inner layers. Polyurethane adhesives used for dry lamination can also be used for bonding cellophane and plastic films.

In the case of a film having a CA effect for fruits and vegetables in which a film containing hinokitiol and its salts is used as an inner layer, a fragrance-retaining film that does not allow hinokitiol and its salts to permeate is required as the outer layer film,
It is preferable to have appropriate oxygen and carbon dioxide permeability.

As the fragrance retaining film having a CA effect, polypropylene, nylon having an appropriate thickness,
Acrylonitrile, ethylene vinyl acetate copolymer, polyvinyl alcohol / vinylidene chloride coat, polyethylene terephthalate and the like are preferable.

As a method of using the moisture-absorbing film of the present invention, it is necessary to use it in a sealed manner such as pillow packaging for continuously packaging food, packaging with a three-side sealed bag, packaging with a zipper bag, and the like.

The outer and inner layers of the plastic film may be preliminarily laminated with an adhesive (registered trademark "Adtex" or the like) on the adhesive surface, or may be applied and dried (polyurethane type).

The inner layer or the through-holes in the inner layer and the intermediate layer can be formed accurately and efficiently with a heating needle roll.

It is convenient to thermally bond a separately formed fastener portion to the film of the present invention for the bag with a fastener, and the bag can be processed by the ordinary bag-making method and apparatus.

For the plastic film used in the present invention, polyethylene, polypropylene, polyester, polybutene, polycarbonate, polyvinyl alcohol, ethylene vinyl acetate copolymer, acrylonitrile and the like can be used in combination depending on the characteristics.

<Packaging Bag> The heat bonding method is easy for the production of the packaging bag and the sealing work after filling the food. For this purpose, the larger the difference in melting point (M, P) between the high-melting point film and the low-melting point film is, the easier it is to use, and at least 20 ° C or higher is desirable, and polypropylene (CPP MP-165 ° C) and low density polyethylene (LDPE) are preferable. The combination of MP-115 ° C) has good processing characteristics and is easy to use.

Aliphatic polyester bionoles (registered trademark, Showa Highpolymer Co., Ltd.) # 1000 (MP-120 ° C) and # 3 having good biodegradability are used as plastic films.
The combination of 000 (MP-90 ° C) is useful for solving environmental problems.

Since the hygroscopic packaging material of the present invention absorbs moisture,
Storage should be sealed. If it absorbs moisture, it must be dried or deaerated under reduced pressure to remove water before use.

The basic structure and working principle of the hygroscopic packaging material of the present invention are shown in FIGS.

In the hygroscopic packaging material of FIG. 3, the outer layer A is made of a thermoplastic synthetic resin film 11 having a high melting point, the intermediate layer B is made of a hygroscopic cellophane 12, and the inner layer C is made of a thermoplastic synthetic resin film 13 having a low melting point. In addition, the inner film 13 has a through hole 14, and a part of the hygroscopic cellophane is in direct contact with the outside atmosphere. This hygroscopic packaging material does not permeate oxygen gas 1 and external moisture 2, and moisture generated from food is controlled by hygroscopic cellophane 12 by absorbing 3 and releasing moisture 4 to keep the inside of the system at a constant humidity. Act. Therefore, the hygroscopic packaging material of FIG. 3 can be used as a hygroscopic / gas barrier packaging material.

The cross-sectional structure of this moisture-absorbing / gas-barrier packaging material is schematically shown in FIG. Reference numerals 15 and 16 denote adhesives.
The manufacturing process is shown in FIG.

As shown in FIG. 6, the low moisture melting film roll 31 is used to manufacture the moisture absorbing / gas barrier packaging material of FIG.
The low melting point film 13 having the adhesive 16 attached thereto is fed out and perforated by the punching needle roll 32 to make it moisture permeable, and then the hygroscopic cellophane 12 fed out from the hygroscopic cellophane roll 33 is heated by the heating roller 34. The high-melting-point film 11 with the adhesive 15 is unwound from the high-melting-point film roll 35 and superposed by the heating roller 34a. Then, in FIG. 6, in order to form a packaging bag, the fastener convex portion side 37 and the fastener concave portion side 38 are further subjected to the fastener fitting and the heat bonding portion 39 via the half-folded plate 36.
Attached, heat-bonded into a bag by the bag-making section 40, cut by a cutter 41, and then stocked as a product bag 42.

In the hygroscopic packaging material of FIG. 4, the outer layer A is composed of the fragrance retaining film 21, the intermediate layer B is composed of hygroscopic cellophane 22, and the inner layer C is composed of the antibacterial film 23. It has a through hole 24 communicating with the hygroscopic cellophane 22. This hygroscopic packaging material allows a part of the external oxygen gas 1 and a part of the internal carbon dioxide gas 6 to permeate, exerts the CA effect, and also absorbs the moisture 2 generated from foods by the hygroscopic cellophane 2.
2 controls, and the antibacterial sheet 23 of the inner layer exhibits an antibacterial action (in the case of hinokitiol 5 and its salts, also a metabolic suppressing action). Therefore, the hygroscopic packaging material of FIG. 4 can be used as a hygroscopic / antibacterial / CA packaging material.

FIG. 7 shows a cross section of the structure of this moisture absorbing / antibacterial / CA packaging material. Reference numerals 15 and 16 denote adhesives. The manufacturing process is shown in FIG.

In the production of the moisture absorbing / antibacterial / CA property packaging material of FIG. 4, as shown in FIG. 8, the antibacterial film 23 with the adhesive 26 is fed from the antibacterial film roll 51,
The hygroscopic cellophane 22 fed from the hygroscopic cellophane roll 52 was superposed on it with a heating roller 53, and a hole penetrating the hygroscopic cellophane 22 and the antibacterial film 23 at the same time was opened by a perforating needle roll 54 to make it moisture permeable. rear,
Further, the fragrance retaining film 21 with the adhesive 25 is unwound from the fragrance retaining film roll 55 and superposed by the heating roller 53a. The subsequent bag manufacturing process is the same as in the case of FIG.

Next, the hygroscopic packaging material of the present invention will be further described with reference to examples.

Example 1 Polyethylene (LDPE 40 μm) and polyolefin adhesive film (registered trademark “Adtex” ET 5 μm)
After laminating, 1.0mm diameter with hot needle, spacing 1.2
mm (aperture ratio 18.5%) and a film bonded with ordinary cellophane (containing PT500 glycerin 10 g / m ² ) and polypropylene (CPP50 μm) with an adhesive (registered trademark “Adtex” ET5 μm) A moisture-absorbing / gas-barrier packaging material was prepared. The sheet was cut into 10 cm squares and dried, and then the equilibrium moisture absorption (20 ° C for 5 days) was measured with a desiccator containing (1) saturated ammonium chloride aqueous solution (RH 80%) (2) tap water (RH 100%). . Table 2 shows the average of the measured values of these 5 samples.
Shown in

[0062]

[Table 2] Example 2 The laminated film of Example 1 has an inner dimension of 220 mm × 310 m.
A bag having a size of m and a heat-seal width of 2 mm was prepared, and 2 kg of polished rice (Koshihikari produced in Niigata) was put therein and a storage test was conducted (5 samples). Under the same conditions, polyethylene bag (LDPE 108μ
m thickness) and a comparative test. The results were as shown in Table 3.

[0063]

[Table 3] Example 3 Low density polyethylene (LLDPE 30 μm) and polyurethane adhesive (Takenate A-72B / Takelac A-)
712B) and then dried with a hot needle to obtain a diameter of 250 μm, 500
Through holes were opened at intervals of μm (aperture ratio 10%), and a laminated film of hygroscopic cellophane (containing PT300 glycerin 5 g / m ² ) and polypropylene (CPP 30 μm) was bonded. 180mm x 230mm with this laminated film
The bag was prepared, 270 g of karin sugar was added, and the bag was stored at room temperature, and the change in peroxide value was observed.

Polypropylene laminated film (CPP / O
PP 80 μm) was used to make a bag of the same size, and the same storage test was performed for comparison. The results are shown in Table 4.

[0065]

[Table 4] Example 4 Polyethylene containing 50 mg / m @ 2 of hinokitiol (LD
PE 15 μm) and hygroscopic cellophane (containing PT400 glycerin 6 mg / m 2) are registered trademarks “Adtex” ET
After adhering with a film (5 μm), a 1.5 mm diameter hole was opened with a hot needle at an opening ratio of 20%, and the registered trademark "Adtex" E
Polypropylene (CPP 25μ with T film (5μm)
m), and a hygroscopic / antibacterial / CA packaging material was prepared.

A bag of 200 mm × 350 mm was made from this packaging material, and 500 g of broccoli was subjected to a storage test at 10 ° C. (A). For comparison, polyethylene (L
The same storage test (B) was performed using a bag of LDPE (80 μm) for comparison. The results are shown in Table 5.

[0067]

[Table 5] Example 5 A low-density polyethylene fastener (manufactured by Showa Hipack Co., Ltd.) was heat-bonded to the moisture-absorbing, antibacterial, CA packaging material of Example 4, and processed into a bag shape. This bag (200mm × 230m
200 g of fresh shiitake mushrooms were placed in m) and a storage test was conducted at 10 ° C. (Test A). Same test as commercially available zipper bag (Asahi Kasei Co., Ltd.) Stock bag polyethylene 50
μm (200 mm × 215 mm) (Test B). The test results are shown in Table 6.

[0068]

[Table 6] As shown in the above Examples 1 to 5, it was revealed that the hygroscopic packaging material of the present invention is effective in various fields as a packaging material for keeping freshness.

[0069]

In summary, according to the present invention, the following excellent effects can be obtained.

According to the first hygroscopic packaging material of the present invention, the external oxygen gas and the outer layer film are blocked by the hygroscopic cellophane of the intermediate layer B and do not permeate inside. Moisture generated from the food inside is absorbed and released by the hygroscopic cellophane through the through holes provided in the inner layer film, and the humidity in the system is stabilized. Therefore, this hygroscopic packaging material functions as a hygroscopic / gas barrier packaging material, and can prevent "steaming" due to the water content of the food inside without enclosing a special desiccant.

According to the second hygroscopic packaging material of the present invention, the outer layer is a fragrance retaining film, the intermediate layer is hygroscopic cellophane, the inner layer is an antibacterial film, and the through holes are formed not only in the inner layer film but also in the intermediate layer. It also penetrates hygroscopic cellophane. Therefore, a part of the external oxygen gas and a part of the internal carbon dioxide gas permeate through the fragrance-retaining film of the outer layer to exert the CA effect, and at the same time, absorb the moisture generated by food from the hygroscopic cellophane. The action is controlled, and the antibacterial sheet in the inner layer exhibits the antibacterial action. Therefore, this hygroscopic packaging material functions as a hygroscopic / antibacterial / CA packaging material, and like the above, prevents "stuffiness" due to the water content of the food inside without enclosing a special desiccant. it can.

Preferably, in the above hygroscopic packaging material, the hygroscopic cellophane in the intermediate layer is made of normal cellophane and contains 5% to 20% by weight of glycerin to obtain hygroscopic properties and safety (food Optimal ones can be obtained from a comprehensive evaluation, such as (use) and processing characteristics.

Preferably, in the above hygroscopic packaging material, it is possible to make the synthetic resin film of the inner layer moisture permeable without fear of electrical connection between the outside and the inside of the bag at the time of heat bonding, and a sufficient opening ratio. And can be achieved without disturbing the strength.

The freshness-keeping packaging bag of the present invention is obtained by processing the hygroscopic packaging material of the present invention into an airtight bag with a fastener, and is suitable as a freshness-keeping packaging bag.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between relative humidity (RH) and glycerin concentration.

FIG. 2 is a diagram showing a relationship between a hole diameter and an interval for making a film transparent and an aperture ratio.

FIG. 3 is a diagram showing a basic configuration and an operation principle in one embodiment of the hygroscopic packaging material of the present invention.

FIG. 4 is a diagram showing a basic configuration and a working principle of another embodiment of the hygroscopic packaging material of the present invention.

5 is a diagram showing a cross-sectional structure of the hygroscopic packaging material of FIG.

FIG. 6 is a diagram showing a manufacturing process of the hygroscopic packaging material of FIG. 3.

7 is a diagram showing a cross-sectional structure of the hygroscopic packaging material of FIG.

FIG. 8 shows a manufacturing process of the hygroscopic packaging material of FIG.

[Explanation of symbols]

 1 Oxygen gas 2 External moisture / water vapor 3 Moisture absorption 4 Moisture release 5 Hinokitiol 6 Carbon dioxide gas 11 Thermoplastic synthetic resin film with high melting point 12 Hygroscopic cellophane 13 Low melting point film 14 Through hole 15, 16 Adhesive 21 Perfume film 22 Hygroscopic cellophane 23 Antibacterial film 24 Through hole 25, 26 Adhesive 31 Low melting point film roll 32 Perforating needle roll 33 Hygroscopic cellophane roll 34, 34a Heating roller 35 High melting point film roll 37 Fastener convex side 38 Fastener concave side 39 Fastener fitting, heat bonding part 40 Bag making part 41 Cutter 42 Product bag 51 Antibacterial film roll 52 Hygroscopic cellophane roll 53, 53a Heating roller 54 Perforating needle roll 55 Perfume film roll

Claims (5)

[Claims] 1. A packaging material comprising three layers, an outer layer, an intermediate layer and an inner layer, wherein the outer layer is a first synthetic resin film, the intermediate layer is a hygroscopic cellophane, and the inner layer is a second synthetic resin film. A hygroscopic packaging material having a through hole in the inner layer film and having a structure in which a part of the hygroscopic cellophane is in direct contact with the outside atmosphere. 2. A packaging material comprising three layers, an outer layer, an intermediate layer and an inner layer, wherein the outer layer is a first synthetic resin film, the intermediate layer is a hygroscopic cellophane, and the inner layer is a second synthetic resin film. The film of the outer layer is a fragrance retaining film,
A hygroscopic packaging material, wherein the inner layer film is made of an antibacterial film and has a through hole communicating with the inner layer film and the hygroscopic cellophane of the intermediate layer. 3. The hygroscopic packaging material according to claim 1, wherein the hygroscopic cellophane of the intermediate layer is ordinary cellophane and contains 5 to 20% by weight of glycerin. 4. The synthetic resin film as the inner layer has a through hole having a hole diameter of 0.1 mm to 1.5 mm and an opening ratio of 5% to 23%. The hygroscopic packaging material described. 5. A packaging bag for maintaining freshness, characterized by processing the hygroscopic packaging material according to claim 1 into an airtight bag with a fastener.