JP2006347582A - Packaging bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging bag excellent in oxygen barrier properties and water vapor barrier properties and additionally, excellent in impact resistance. <P>SOLUTION: The packaging bag of the present invention is used for storing a water vapor generating body. The packaging bag consists of an outermost layer consisting of a heat-resistant resin film layer and a laminated film with at least two layers of metal-deposited film layers positioned on the inside of the resin film layer. Respective metal-deposited film layers preferably consist of aluminum-deposited polypropylene films. In particular, it is preferable that the metal-deposited film layer on the side near to the resin film layer consists of an aluminum-deposited OPP film, and the metal-deposited film layer on the side far from the resin film layer consists of an aluminum-deposited CPP film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a packaging bag used for storing a steam generator and a packaging material thereof.

  So-called chemical warmers using heat generated by an oxidation reaction of an oxidizable metal such as iron powder are usually distributed in the market in a sealed state in a packaging bag in order to cut off contact with air. In use, the packaging bag is opened and the body is taken out, and the body is brought into contact with oxygen in the air to generate heat. The performance required for packaging bags of chemical warmers includes oxygen barrier properties that prevent oxidizable metals from coming into contact with oxygen during storage. By the way, it is known that a trace amount of hydrogen is generated in the packaging bag when stored in a state where the oxidizable metal and oxygen are not in contact with each other. When the hydrogen accumulates in the packaging bag, the problem of bag swelling occurs. For this reason, the packaging bag is required to have hydrogen permeability that does not bulge during storage.

  As a packaging bag of a chemical warmer having oxygen barrier properties, for example, one in which a deposited film of an inorganic oxide such as silicon oxide is provided on one surface of a base film such as a biaxially stretched nylon 6 film is known (Patent Document) 1 and 2). According to this packaging bag, even if the warmer is hermetically stored and stored, the bag is not swollen and the performance of the warmer is not changed.

  By the way, the present applicant has previously proposed a water vapor generator using heat generated by an oxidation reaction of an oxidizable metal (see Patent Document 3). This water vapor generator contains a lot of water as compared with a normal chemical warmer. Therefore, the packaging bag for storing the water vapor generating body is required to have a water vapor barrier property in addition to the oxygen barrier property. However, when the water vapor generator is hermetically stored in the packaging bag described in Patent Documents 1 and 2 described above and stored for a long period of time, the water is gradually released to the outside. It will not be possible to exert the ability.

  When a film laminated with aluminum is used as a packaging bag material, the packaging bag is excellent in both oxygen barrier properties and water vapor barrier properties, and prevents deterioration in heat generation characteristics due to long-term storage. Is done. However, as described above, the packaging bag may be swollen by a small amount of hydrogen generated during storage, and the appearance impression may be lowered. Therefore, hydrogen permeability that is low enough to prevent swollenness is required. By the way, regarding the film for packaging bags, it is known that there is a high correlation between hydrogen permeability and oxygen permeability. In other words, hydrogen permeability and oxygen barrier properties are in a trade-off relationship. Thus, (a) high water vapor barrier property, (b) high oxygen barrier property, and (c) hydrogen permeability that can prevent the bag from being swollen can be sufficiently satisfied. The material has not been obtained yet.

JP 2002-86607 A JP 2002-120860 A JP 2002-78728 A

  Accordingly, an object of the present invention is to provide a packaging bag and its packaging material that can eliminate the above-mentioned drawbacks of the prior art.

  The present invention provides a packaging bag for storing a steam generator comprising an outermost layer composed of a heat-resistant resin film layer and a laminated film having two or more metal vapor deposited film layers positioned inside the resin film layer. The object has been achieved.

  The present invention also provides a packaging material for a packaging bag for storing a water vapor generator, comprising an outermost layer comprising a heat-resistant resin film layer and a laminated film having two or more metal vapor deposited film layers positioned inside the resin film layer. It is to provide.

  Since the packaging bag and packaging material of the present invention are excellent in oxygen barrier property and water vapor barrier property and have hydrogen permeability, deterioration of heat generation characteristics of the water vapor generator during storage is prevented, and packaging is also possible. Swelling of the bag is prevented from occurring. In addition, it has high impact resistance, particularly impact resistance at low temperatures.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 schematically shows an example of a preferable multilayer structure in the laminated film constituting the packaging material of the present invention. The laminated film is a heat-resistant resin film layer that is the outermost layer, a first metal vapor deposition film layer located inside the resin film layer, and an innermost layer located inside the first metal vapor deposition film layer. It has the 2nd metal vapor deposition film layer to comprise.

  The water vapor generator accommodated in the packaging bag made of the packaging material of the present embodiment generates water vapor using the heat generated by the heat generating element containing the oxidizable metal. The steam generator is configured such that a heating element is accommodated in a container having moisture permeability at least partially.

  The packaging material composed of a laminated film having a multilayer structure shown in FIG. 1 blocks the permeation of oxygen from the outside to some extent by each metal-deposited resin film layer, and allows a small amount of hydrogen to permeate from the inside. Thereby, the oxidation of the oxidizable metal contained in the water vapor generator hermetically stored in the packaging bag is effectively prevented. Further, the swelling of the packaging bag due to hydrogen generated during storage is effectively prevented. Furthermore, since each metal vapor deposition resin film layer has a high water vapor barrier property, the water contained in the water vapor generator is effectively prevented from being released out of the bag. Each metal vapor deposition resin film layer is arranged so that the resin film faces the inside of the packaging material and the metal vapor deposition film faces the outside of the packaging material.

  As a metal vapor deposition film layer, what vapor-deposited the metal on one surface of the film which consists of various thermoplastic resins is used. As the metal to be deposited, it is preferable to use aluminum from the viewpoint of high oxygen barrier property and water vapor barrier property and economical efficiency. If aluminum is deposited in a thickness of 0.02 to 0.08 μm, satisfactory oxygen barrier properties and water vapor barrier properties can be obtained. As described in Patent Documents 1 and 2 described above, a resin film having a vapor deposition film of inorganic oxide such as silicon oxide is generally used in a packaging material conventionally used as a packaging bag for chemical warmers. It is not common to use a resin film having a vapor deposition film of the metal itself.

  Examples of the resin film on which the metal is deposited include those made of polypropylene, polyethylene, polyethylene terephthalate, or the like. Depending on the type of resin and the processing method of the film, the properties of the obtained film may be different or may vary. A metal vapor-deposited film obtained by vapor-depositing a metal on a biaxially stretched polypropylene film, an unstretched polypropylene film, or a polyethylene film has excellent water vapor barrier properties. However, the gas barrier property is inferior. The most frequently used barrier material is a metal vapor deposition film called VMPET, which is a polyethylene terephthalate film deposited with aluminum. VMPET is excellent in both water vapor barrier properties and gas barrier properties, and has an advantage of high adhesion strength between aluminum and a polyethylene terephthalate film. However, due to the high melting point of polyethylene terephthalate, VMPET is inferior in sealing properties. Apart from VMPET, in recent years, high adhesion type metal vapor deposition films using polypropylene have been developed. Therefore, it is preferable to use a polypropylene metal vapor-deposited film from the viewpoint of sealing properties. The resin film on which the metal is deposited preferably has a thickness of 10 to 70 μm, particularly 25 to 55 μm, from the viewpoint of high gas barrier properties and good sealing properties.

  One feature of the laminated film constituting the packaging material of the present embodiment is that two metal-deposited film layers are laminated. As a result of the study by the present inventors, it was found that the metal-deposited film has a sufficiently high oxygen barrier property and water vapor barrier property even when it is used as a single layer. On the other hand, the metal vapor-deposited film cannot be said to have sufficient impact resistance, for example, when a water vapor generator is sealed and stored in a packaging bag made of a metal vapor-deposited film, and a drop test is performed to drop it from a predetermined height, It has also been found that cracks and the like occur in the packaging bag. In particular, it has been found that impact resistance is further reduced at low temperatures. In view of the use of the steam generator, the low impact resistance of the packaging bag at a low temperature is a serious problem.

  In order to solve the above-mentioned problems, the present inventors diligently studied and found that it is an effective means to laminate two metal vapor deposited film layers. It has also been found that by adopting this means, the oxygen barrier property and the water vapor barrier property are further enhanced. Furthermore, by laminating two metal deposited film layers, there is an advantage that even if delamination or cracks occur in either layer, the other layer can cover it.

  In particular, the first metal vapor-deposited film layer located on the side close to the heat-resistant resin film layer is formed by depositing aluminum on a biaxially stretched polypropylene (hereinafter also referred to as OPP) film, and is far from the heat-resistant resin film layer. When the second metal deposited film layer located on the side is made of a non-stretched polypropylene (hereinafter also referred to as CPP) film deposited with aluminum, the impact resistance at low temperatures is extremely high.

  The OPP film is obtained by stretching and fixing a thick CPP film biaxially and vertically. The OPP film has a higher film strength than the CPP film. Therefore, the impact resistance of a packaging bag can be improved by using an aluminum vapor deposition OPP film as a 1st metal vapor deposition film layer.

  While the OPP film has the above-mentioned advantages, it may be difficult to deposit metal densely. If the metal cannot be densely deposited, the oxygen barrier property and water vapor barrier property cannot be sufficiently improved. On the other hand, the CPP film can deposit metal densely. In particular, a low-melting grade CPP film having a lower melting point than that of ordinary polypropylene has very high adhesion to a metal vapor deposition film. Then, the oxygen barrier property and water vapor | steam barrier property of a packaging bag can be improved by using an aluminum vapor deposition CPP film as a 2nd metal vapor deposition film layer which is an innermost layer.

  Thus, in this embodiment, the packaging bag is excellent in oxygen barrier property and water vapor barrier property by arranging the aluminum vapor deposition OPP film on the outer layer side and the aluminum vapor deposition CPP film on the inner layer side. Become. In addition, the impact resistance, particularly the impact resistance at low temperatures, is high. In the present invention, an aluminum vapor-deposited CPP film may be disposed on the outer layer side, and an aluminum vapor-deposited OPP film may be disposed on the inner layer side. Two layers of film can be used. However, the most effective combination is a combination of an aluminum-deposited OPP film on the outer layer side and an aluminum-deposited CPP film on the inner layer side, as described above.

  The heat resistant resin film layer constituting the outermost layer of the packaging material is mainly used for the purpose of printing on the packaging bag and for the purpose of protecting the metal vapor deposited film layer. As the resin constituting the heat resistant resin film layer, one having a melting point of about 200 to 300 ° C. is preferably used. Examples of such a resin include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides, and polyimides. Although the heat resistant resin film layer depends on the film strength, if the thickness is 5 to 20 μm, desired performance is exhibited.

  In order to produce a laminated film composed of the above layers, for example, a film constituting each layer may be produced and dry laminated. Examples of the adhesive used for the dry laminate include an adhesive resin made of a polyolefin polymer modified with a carboxylic acid such as maleic acid or maleic anhydride or an anhydrous graft polymer thereof.

The laminated film composed of the above layers has an oxygen transmission rate (JIS K7126B, 20 ° C., 0% RH) of 0.5 to 10 cc / m ² 24 h / atm, particularly ^{2 to} 10 cc / m ² 24 h / atm. Lower value. Further, the water vapor transmission rate (JIS K7129B, 40 ° C., 90% RH) is as low as 0.05 to 0.5 g / m ² 24 h, particularly 0.05 to 0.2 g / m ² 24 h.

  The thickness of the laminated film is not critical in the present invention, and is determined from the viewpoint of ease of production of the laminated film and economic efficiency. In general, satisfactory results are obtained with a thickness of 30-100 μm.

  As a packaging bag comprised from the packaging material of this embodiment, what is shown to Fig.2 (a) and (b) is mentioned, for example. The bag 1 shown in FIG. 2 (a) is formed by stacking two identical packaging materials 2 so that their innermost layers are opposed to each other, and then heat-sealing the peripheral portions of these three sides. While forming the part 3, it is a three-sided seal type with the remaining one side opened. The water vapor generator 10 is put into the bag 1 through the opening of the bag 1 and the opening is heat-sealed, whereby the water vapor generator 10 is hermetically stored.

  A bag 1 ′ shown in FIG. 2 (b) is a cylindrical body (not shown) having a longitudinal seal portion 4 which is heat-sealed so that one side of a longitudinally long rectangular packaging material 2 overlaps. Then, the water vapor generator 10 is put into the cylindrical body, and then heat sealing is performed in the width direction of the cylindrical body at positions before and after the water vapor generator 10 to form the horizontal seal portions 5 and 5. Then, after that, the cylindrical body was obtained by cutting in the width direction at the position of the lateral seal portion 5.

  As the water vapor generator stored in the packaging bag, for example, the one described in JP-A-2002-78728 (Patent Document 3) described above can be used. Moreover, what is shown in FIG.3 and FIG.4 can also be used. The steam generator 10 shown in FIG. 3 has a flat rectangular shape, and includes a heat generating portion 12 and a housing 13 for housing the heat generating portion 12. The container 13 has a flat bag shape, and a plurality of sheet materials are bonded together to form a hollow bag shape. The container 13 is at least part of a breathable portion having moisture permeability. The heat generating portion contains water in addition to the oxidizable metal, and steam is generated by utilizing the heat generated by the heat generating portion in contact with oxygen. The water vapor is released to the outside from the breathable portion of the container.

  The heat generating part 12 is made of a heat generating sheet or a heat generating powder containing an oxidizable metal, a reaction accelerator, an electrolyte and water. When the heat generating part 2 is formed of a heat generating sheet, the heat generating sheet is preferably composed of a fiber sheet containing an oxidizable metal, a reaction accelerator, a fibrous material, an electrolyte, and water. That is, it is preferable that the exothermic sheet is one in which a fiber sheet containing an oxidizable metal, a reaction accelerator, a fibrous material, and an electrolyte is in a water-containing state. In particular, the exothermic sheet is preferably configured by containing an electrolyte aqueous solution in a molded sheet containing an oxidizable metal, a reaction accelerator, and a fibrous material. Examples of the heat generating sheet include those obtained by wet papermaking, and laminates obtained by sandwiching heat generating powder with paper or the like. Such a heat generating sheet can be manufactured using, for example, the wet papermaking method described in Japanese Patent Application Laid-Open No. 2003-102761 related to the previous application of the present applicant, or the extrusion method using a die coater. On the other hand, when the heat generating part 2 is made of heat generating powder, the heat generating powder preferably includes an oxidizable metal, a reaction accelerator, a water retention agent, an electrolyte, and water. Of the exothermic sheet and exothermic powder, it is preferable to use the exothermic sheet because it is easy to make the temperature distribution uniform and the carrying ability of the oxidizable metal is excellent.

  In the water vapor generator 10, the container 13 is formed in a flat bag shape by joining the peripheral edges of the film 13a and the film 13b to each other. The film 13a is a moisture permeable film. The film 13b is a moisture permeable film having a moisture permeability lower than that of the film 13a or a hardly moisture permeable film. That is, in the container 13, the moisture permeability is higher on one side than on the other side. The film 13a allows water vapor generated from the heat generating part 12 to pass through. However, the film 13b is difficult to pass water vapor. That is, a large amount of water vapor is preferentially released to the outside from one side of the container 13, that is, the film 13a side. The water vapor generator 10 is used such that the side of the film 13a faces an object to be subjected to water vapor. On the outside of the film 13a and the film 13b, non-woven fabrics 3c and 3d such as an air-through non-woven fabric which is a sheet material having a good texture are arranged for the purpose of enhancing the texture of the water vapor generator 10.

  The steam generator 10 having such a configuration can increase not only the surface temperature of the application site but also the deep temperature of the human body by applying it to the body surface of the human body, for example. As a result, the blood flow throughout the body increases and the temperature at the application site increases, as well as the peripheral temperature of the fingertips and the like. In addition, there is an effect of keeping the peripheral temperature warm. Therefore, the water vapor generator 10 has effects such as blood circulation promotion, muscle fatigue, muscle stiffness and muscle pain relief, coldness relief, and neuralgia relief.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the packaging material of the above-described embodiment, two metal deposited film layers are laminated, but three or more metal deposited film layers may be laminated instead.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “% by weight”.

[Example 1]
A 12 μm thick biaxially stretched polyethylene terephthalate film, a 25 μm thick aluminum vapor-deposited OPP film, and a 40 μm thick aluminum vapor deposited high adhesion low melting point CPP film layer were laminated and integrated by a dry lamination method. The resulting packaging material made of the laminated film was made into a bag as shown in FIG. 2 (b), and the steam generator having the structure shown in FIGS. 3 and 4 was hermetically stored therein. The heat generating part in the steam generator was composed of a heat generating sheet manufactured by wet papermaking. The exothermic sheet was prepared by injecting 60 parts by weight of a 5% sodium chloride aqueous solution into 100 parts by weight of a sheet made of paper having a basis weight of 180 g / m ² containing 75% iron powder, 10% activated carbon and 15% pulp. Met. The heat generating sheet had a size of 80 mm × 100 mm, and was used by superposing six sheets.

[Comparative Example 1]
A 20 μm thick OPP film and a 40 μm thick aluminum-deposited high-contact CPP film layer were laminated and integrated by a dry laminating method. A packaging bag was produced in the same manner as in Example 1 by using the obtained packaging material made of the laminated film. The same steam generator as in Example 1 was hermetically stored in the packaging bag.

[Evaluation]
The packaging bag containing the steam generator obtained in Example 1 and Comparative Example 1 was stored in an environment of 50 ° C. and 0% RH. Changes in weight during storage were measured to evaluate water vapor barrier properties. Moreover, the volume change of the bag during storage was measured, and the oxygen barrier property was evaluated. The results are shown in FIGS.

  As is apparent from the results shown in FIGS. 5 and 6, it can be seen that the packaging bag of Example 1 has little weight change and volume change. From these results, it can be seen that the packaging bag of Example 1 has high water vapor barrier properties and oxygen barrier properties. Although not shown in the drawing, the packaging bag containing the steam generator of Example 1 did not swell even when stored for a long time.

  Separately from the above evaluation, the packaging bag containing the steam generator obtained in Example 1 and Comparative Example 1 was stored in an environment at 5 ° C. for 1 day, and then subjected to a drop test to evaluate the impact resistance of the packaging bag. did. The state of occurrence of cracks was evaluated when 10 each of the packaging bags containing water vapor generators were dropped from a height of 1 m onto the concrete floor. As a result, no crack was generated in the packaging bag of Example 1, whereas in the packaging bag of Comparative Example 1, three bags were cracked. From this result, it can be seen that the packaging bag of Example 1 has higher impact resistance at low temperatures than the packaging bag of Comparative Example 1.

FIG. 1 is a schematic view showing an example of a preferable multilayer structure of a laminated film in the packaging bag of the present invention. FIGS. 2A and 2B are schematic views showing examples of packaging bags, respectively. FIG. 3 is a perspective view showing an example of a water vapor generator. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a graph showing the results of evaluating the water vapor barrier properties of the packaging bags obtained in Example 1 and Comparative Example 1. FIG. 5 is a graph showing the results of evaluating the oxygen barrier properties of the packaging bags obtained in Example 1 and Comparative Example 1.

Explanation of symbols

1 Packaging Bag 2 Packaging Material 10 Water Vapor Generator

Claims (6)

  A packaging bag for storing a steam generator, comprising an outermost layer composed of a heat-resistant resin film layer and a laminated film having two or more metal vapor deposited film layers positioned inside the resin film layer.   The packaging bag according to claim 1, wherein each of the metal vapor-deposited film layers is formed by depositing aluminum on a polypropylene film. Having two metal-deposited film layers;
The metal vapor deposition film layer on the side close to the resin film layer is formed by depositing aluminum on a biaxially stretched polypropylene film,
The packaging bag according to claim 2, wherein the metal vapor deposition film layer on the side far from the resin film layer is formed by depositing aluminum on an unstretched polypropylene film.   The packaging bag according to any one of claims 1 to 3, wherein the water vapor generator generates water vapor using heat generated by a heat generating part containing an oxidizable metal.   The packaging bag according to any one of claims 1 to 4, wherein the heating element is in the form of a sheet containing the oxidizable metal and a fibrous material. A packaging material for a packaging bag for storing a water vapor generator, comprising an outermost layer comprising a heat-resistant resin film layer and a laminated film having two or more metal vapor deposition film layers located inside the resin film layer.

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