JPH0231408Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a packaging bag for retort sterilization, and more specifically, it is large in size, and has high breaking strength, puncture resistance, and
This invention relates to a large retort sterilization packaging bag that has excellent mechanical strength such as bending fatigue resistance. Sealed packaging for retort sterilization currently in use,
There is a strong tendency for so-called "retort pouches" to increase in size, and the packaging materials used for this purpose have high breaking strength, puncture resistance, and
Mechanical strength such as bending fatigue resistance is particularly required. In order to meet these demands, commonly used packaging materials with a three-layer structure, such as the outermost layer made of a film with excellent mechanical strength and printability,
Packaging materials consisting of a second layer of aluminum foil and an innermost layer of heat-sealable film cannot compensate for the strength, so there is a gap between the second layer of aluminum foil and the innermost layer of heat-sealable film. Currently, packaging materials having a four-layer structure including a third layer of a film with excellent mechanical strength are often used. Typical configurations of this four-layer packaging material include biaxially oriented polyester film, biaxially oriented polypropylene film, or biaxially oriented 6-
A nylon film is used, and an aluminum foil is usually used as the second layer laminated next to the outermost layer in order to provide gas barrier properties and light shielding properties. For the third layer, an unstretched 6-nylon film or a biaxially stretched 6-nylon film is used to provide mechanical strength such as breaking strength, puncture resistance, and bending fatigue resistance. Although a heat-sealable film is used as the inner layer and a four-layer packaging material is constructed, it does not completely meet the suitability requirements for retort sterilization packaging bags, especially large-sized packaging bags. That is, the outermost layer of the conventional packaging bag has the following drawbacks. First, the biaxially oriented polyester film used for the outermost layer has quite low mechanical strength such as puncture resistance and bending fatigue resistance, and with the current film, even if a film with sufficient mechanical strength is laminated as the third layer, This is insufficient to improve the mechanical strength of packaging bags. Biaxially oriented polypropylene films or biaxially oriented 6-nylon films have sufficient strength in this respect and may be used, but there are other major drawbacks when these films are used as the outermost layer. The drawback is that these films have poor dimensional stability during heat sterilization, and therefore, when used, there are temperature restrictions for retort sterilization or their use is impossible. In other words, biaxially stretched polypropylene film has poor dimensional stability when subjected to high-temperature retort sterilization, especially at temperatures above 125°C, and has a maximum
It shrinks by as much as 15%, and when retort pouches made using this material are subjected to retort sterilization, the outer edges of the pouches become distorted. In severe cases, a so-called delamination phenomenon in which the aluminum foil peels off occurs. On the other hand, biaxially stretched 6-nylon film has a high heat absorption rate, and when subjected to retort sterilization at high temperatures, it not only has poor dimensional stability, but also has high water absorption, which further promotes delamination. This often occurs even below 125°C, making it virtually impossible to use. This is because the aluminum foil used for the second layer is
This is because there is no heat shrinkage at all, compared to the high heat shrinkage when these films are used as the outermost layer, and packaging materials with such a layered structure are not suitable for packaging bags for retort sterilization. This is the biggest drawback when using it. Therefore, at present, the films suitable for the outermost layer are biaxially oriented polyester film and biaxially oriented polypropylene film, but the former lacks mechanical strength and the latter has limitations in the temperature conditions under which it can be used. is also an unsatisfactory material. Next, for the third layer of film, unstretched 6-nylon film and biaxially oriented 6-nylon film are used, but these are currently used to improve the mechanical strength of the packaging bag, which is the original purpose of this layer. However, it may be almost satisfactory if a biaxially oriented polypropylene film or a biaxially oriented 6-nylon film is used as the outermost layer to obtain a synergistic effect of the combination. However, when these films are used as the outermost layer, there are drawbacks, so in fact, this combination cannot be used or is subject to restrictions. Furthermore, when a biaxially stretched polyester film is used as the outermost layer, sufficient strength cannot be obtained. The present inventors have developed a material that is strong in terms of breaking strength, puncture resistance, bending fatigue resistance, etc., has sufficient mechanical strength required for large retort pouches, has excellent dimensional stability, and has no delamination. As a result of research on laminated materials that do not occur, a biaxially oriented 6-6 nylon film was used instead of the biaxially oriented polyester film, biaxially oriented polypropylene film, or biaxially oriented 6-nylon film conventionally used as the outermost layer. We have discovered that by using this, it is possible to obtain a large retort sterilization packaging bag that compensates for the various drawbacks of the current laminated materials and solves the problems of the conventional technology, and based on this knowledge, we have completed the present invention. be. That is, the gist of the present invention is that the outermost layer is made of a biaxially oriented 6-6 nylon film, the second layer is made of aluminum foil, and the third layer is made of a biaxially oriented 6-6 nylon film or a biaxially oriented 6-6 nylon film. It is formed from a laminated material made by sequentially laminating a heat-sealing film and a heat-sealing film, and the size is 160 to 380 mm x
This is a large retort sterilization packaging bag characterized by a size of 200 to 500 mm. Hereinafter, the present invention will be explained in detail with reference to the drawings. As shown in the first figure, the laminated material 6 used in the present invention includes an outermost layer 1 made of a biaxially oriented 6-6 nylon film, a second layer 2 made of aluminum foil, and a biaxially oriented 6-6 nylon film or a biaxially oriented 6-6 nylon film. A third layer 3 made of a stretched 6-6 nylon film and a heat-sealable film 4 are laminated in sequence. Note that 5 indicates an adhesive layer. Therefore, in the present invention, biaxial stretching 6
The outermost layer made of -6 nylon film provides dimensional stability and printability, as well as breaking strength and
It provides mechanical strength such as puncture resistance and bending fatigue resistance, and is laminated together with the third layer to improve the overall strength of the large retort sterilization packaging bag. Further, the second layer made of aluminum foil is laminated to provide gas barrier properties and light shielding properties. The third layer is laminated together with the outermost layer in a large retort sterilization packaging bag in order to improve mechanical strength such as breaking strength, puncture resistance, and bending fatigue resistance. The material for the third layer is biaxially stretched 6-
Since a 6-6 nylon film is used, any of the above-mentioned materials may be used, but a biaxially stretched 6-6 nylon film is particularly preferred. That is, when a biaxially stretched 6-6 nylon film is used as the material for the third layer, a large retort sterilization packaging bag with particularly excellent mechanical strength can be obtained. In addition, as the heat-sealable film, unstretched polypropylene, unstretched high-density polyethylene, unstretched medium-density polyethylene, unstretched ethylene/α-olefin copolymer, etc. can be used, but sterilization applied to retort sterilization is preferable. Unstretched polypropylene, which can be universally applied within a temperature range, is preferred. By using the above laminated materials,
The retort sterilization packaging bag has a size of 160 to 380 mm x 200 to 500 mm, that is, a capacity of 350 mm, as shown in the second figure.
Even as a packaging bag for large retort sterilization of 5,000 ml, it has excellent mechanical strength such as breaking strength, puncture resistance, and bending fatigue resistance, and not only does the bag not break during the transportation process, but also has excellent thermal stability. It has the advantage of not causing deformation or delamination due to heat sterilization. Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Biaxially oriented 6-6 nylon film ( ^6-6 ON
The outermost layer consists of aluminum foil (hereinafter abbreviated as A1), the second layer consists of 9μm, and the biaxially stretched 6-nylon film (hereinafter abbreviated as ^6- ON).
Three types of laminated materials were prepared by sequentially laminating a third layer of 15 μm or ^6-6 ON 14 μm and a 70 μm unstretched polypropylene film (hereinafter abbreviated as CPP) as a heat-sealable film. That is, the structure of this laminated material is abbreviated and shown as follows: (1) ^6-6 ON14μm/A19μm/ ^6- ON15μm/
CPP70μm and (2) ^6-6 ON14μm/A19μm/ ^6-6 ON14μm/
CPP is 70μm (note that / indicates the adhesive layer for bonding). Furthermore, for comparison, the outermost layer film was biaxially oriented polyester film (hereinafter abbreviated as PET) 12 μm, biaxially oriented polypropylene film (hereinafter abbreviated as OPP) 20 μm or ^6- ON 15 μm, and the third layer was
Laminated materials having the same four-layer structure as above, each consisting of 20 μm of ^6- CN or 15 μm of ^6- ON, were prepared. In other words, the configurations of the laminated materials created for these comparisons are abbreviated and shown as (3) PET12μm/A19μm/6-CN20μm/ ^6- CN20μm/
CPP70μm, (4) PET12μm/A19μm/ ^6- ON15μm/
CPP70μm, (5) OPP20μm/A19μm/ ^6- CN20μm/
CPP70μm, (6) OPP20μm/A19μm/ ^6- ON15μm/
CPP70μm, (7) ^6- ON15μm/A19μm/ ^6- CN20μm/
CPP70μm, (8) ^6- ON15μm/A19μm/ ^6- ON15μm/
CPP is 70μm. All of these laminated materials are laminated using a current two-component urethane adhesive for retort sterilization, and are laminated (bonded) using a dry laminator and then heat-cured using conventional methods. Ivy. The nine types of laminated materials thus obtained were then processed into large retort sterilization packaging bags with external dimensions of 280 x 420 mm (including a seal width of 10 mm) and subjected to the following comparative tests. Test 1 After filling with water 3 as contents and sealing by heat sealing, the appearance of the packaging bag after sterilization was observed using a pressurized hot water retort sterilizer under predetermined conditions. The number of samples is 50 in each packaging bag. The results are summarized in Table 1. As can be seen from Table 1, ^6- ON15μm/A19μm/ ^6- CN20μm/
CPP70μm(7), ^6- ON15μm/A19μm/
^6- ON15μm/CPP70μm(8) and OPP20μm/A19μm/ ^6- CN20μm/ in sterilization above 125℃
CPP70μm(5), OPP20μm/A19μm/
^6- In the packaging bag made of ON15μm/CPP70μm(6),
Shrinkage deformation and delamination of the outermost layer occurred frequently, making it almost unusable. On the other hand, PET12μm/A19μm/ ^6- CN20μm/
CPP70μm(3) and PET12μm/A19μm/
^6- In the packaging bag made of ON15μm/CPP70μm(4),
The appearance is good, and ^{the 6-6} ON14μm/
A19μm/ ^6- ON15μm/CPP70μm(1) and
^6-6 ON14μm/A19μm/ ^6-6 ON14μm/CPP70μm
The packaging bag made of (2) was also good.

[Table] Test 2 After filling with water 3 as the content and sealing with heat seal in the same way as Test-1 above, Test-1
Retort sterilization was performed at 120°C for 30 minutes, which is the mildest retort sterilization condition. The obtained sterilized packaging bags containing the contents were packed in a cardboard box, with 4 bags per cardboard box, arranged in 2 stages x 2 rows. The samples obtained in this way are
Subjected to various tests. (1) Drop test 3 different sides of a cardboard box from a height of 90 cm
It fell seven times in succession so that each of the edges and one corner, a total of seven locations, first came into contact with the floor surface. The indoor ambient temperature during the test was 5°C. (2) Vibration test Using a vibration test machine, a cardboard box was placed vertically (vertical) and horizontally (horizontal) for 1 hour each, for a total of 2 hours under the conditions of a vibration frequency of 960 times/min., a swing width of ±2 mm, and a vibration acceleration of 2 G. It vibrated for hours. The indoor ambient temperature during the test was 5°C. The number of specimens used for testing these type 2 bases was 20 cardboard boxes each, or 80 packaging bags. After these tests were completed, the cardboard box was opened and the number of leaks due to damage such as pinholes and cuts in the packaging bag was counted to determine the practical strength.
The results are shown in Table 2.

[Table] Unable to strike.
As you can see from Table 2, PET12μm/A19μm/
^6- CN20μm/CPP70μm(3), PET12μm/
A19μm/ ^6- ON15μm/CPP70μm(4),
OPP20μm/A19μm/ ^6- CN20μm/CPP70μm(5)
Or OPP20μm/A19μm/ ^6- ON20μm/
It is clear that packaging bags made of CPP70μm(6) lack practical strength. On the other hand, ^{the 6-6} ON14μm/A19μm/
^6- In a packaging bag made of ON15μm/CPP70μm(1),
It has a strength that poses no practical problems, and ^6-6 ON14μm/
The packaging bag made of A19μm/ ^6-6 ON14μm/CPP70μm (2) has the best results. As shown in the above test results, the large-sized packaging bag for retort sterilization of the present invention, which is formed using a specific laminated material, has excellent mechanical strength and is resistant to liquids caused by breakage or pinholes during the retort sterilization process or transportation process. Not only does it not leak, it also has excellent thermal stability, and even when subjected to retort sterilization, it does not cause heat shrinkage (curving) or deformation.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the laminated material used in this invention.
FIG. 2 is a sectional view of the large-sized retort sterilization packaging bag of the present invention. 1... Outermost layer made of biaxially stretched 6-6 nylon film, 2... Second layer made of aluminum foil
Layer 3... Third layer, 4... Heat sealable film layer.

Claims (1)

[Scope of utility model registration request] Biaxially oriented 6-6 The outermost layer is made of nylon film, and the second layer is made of aluminum foil, biaxially oriented 6
- formed from a laminated material formed by sequentially laminating a third layer of nylon film or biaxially oriented 6-6 nylon film and a heat-sealable film;
A large retort sterilization packaging bag characterized by a size of 160 to 380 mm x 200 to 500 mm.