Packaging with a function to prevent bending and deformation of the opening

Abstract

To provide a package capable of preventing an unsealed opening from being curved and deformed without being limited to a material of the package when taking out a content of food or the like by cutting the package, according to those each relating to the package made of a synthetic resin film.SOLUTION: A thermally fusible belt-like film 1 is inserted to a front face film 4a and a back face film 4b on an opening preparation line 8 of a package 4, and an unsealed opening is prevented from being curved and deformed when cutting along the opening preparation line 8 for opening, by joining the belt-like film 1 with the front face film 4a and the back face film 4b in a shape where a plurality of thermally fusible parts 2 and non-thermally fusible parts 3 are provided.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a packaging body made of a synthetic resin film that prevents the opening from bending and deforming when a portion of the packaging body is cut off to open it and remove the contents, such as food. [Background technology]

[0002] Today, pre-cooked food products in sealed packages are widely available due to the convenience of serving food.

[0003] When using these products, it is common to transfer the contents to tableware such as plates or bowls before eating, but preparing and washing the tableware can be a hassle, and consumers want to be able to finish their meals more quickly and conveniently.Therefore, there is a demand for a function that allows products in a sealed package to be heated directly in a microwave oven or in a hot water bath, and then the package can be used as tableware after opening.

[0004] However, with conventional packaging made from synthetic resin film, when the packaging is opened after undergoing processes such as hot filling, boiling sterilization, or retort sterilization, or after the sealed packaged contents are heated in a microwave oven or in a hot water bath, the opening inevitably curves and deforms.

[0005] Furthermore, when the opening is curved or deformed, the area of the opening becomes smaller, and the curved edge of the film can easily get caught on the contents or chopsticks or other utensils, making it difficult to eat and causing the contents to splash out and make a mess around the area. Summary of the Invention [Problem to be solved by the invention]

[0006] Packaging made from synthetic resin films meets packaging functions by selecting synthetic resin films with a wide variety of properties according to the packaging specifications and layering multiple synthetic resin films to ensure the physical properties necessary for protecting the contents, such as strength, airtightness, gas barrier properties, heat resistance, cold resistance, and content resistance, as well as processing suitability, such as printability, bag-making suitability, and content filling suitability.

[0007] Because a package made of synthetic resin film is made up of laminated synthetic resin films with different thermal and mechanical properties, differences in shrinkage and tensile elongation occur between the laminated single films due to moisture absorption, heating, cooling, and tensile tension caused by volume expansion within the package that occur in the package during each process, such as sterilization, distribution, and cooking. This difference in shrinkage and tensile elongation between the laminated single films is thought to be a major cause of the opening curving and deforming when the package is opened.

[0008] Furthermore, while the use of metal foil such as aluminum gives the packaging rigidity and deadhold properties, making it possible to maintain the shape of the opening, it also makes it impossible to use metal detectors or microwave ovens, which are used in product inspection processes.Furthermore, the use of metal foil, which is a different material from synthetic resin, makes it difficult to recycle the packaging.

[0009] In light of the above, Patent Document 1 shows that the shape of the opening can be maintained by introducing a uniaxially oriented high-density polyethylene tape and a film laminated with linear low-density polyethylene on either the front or back surface or both surfaces of the high-density polyethylene tape along the intended opening line. However, uniaxially oriented high-density polyethylene tape is very prone to tearing in the stretched direction, making it difficult to process into bags. Furthermore, laminating linear low-density polyethylene on this facilitates bag processing, but since the material is limited to polyethylene, the heat-sealable adherend itself is also limited to polyethylene. Furthermore, packages using polyethylene as a sealant film are generally known to have low heat resistance and cannot withstand high-stress conditions such as boiling sterilization and retort sterilization, limiting their uses.

[0010] Furthermore, Patent Document 2 discloses that polyethylene terephthalate film, polyamide film, or polypropylene film, which have the property of being able to be torn in a straight line horizontally along the body of the bag, can be used as the film that makes up the packaging, but although there is a description of an evaluation of the ease of tearing by hand when opening, there is no mention of an evaluation of the ability of the opening to maintain its shape. Furthermore, while these films are generally available on the market, they are specialty products and therefore expensive, and packaging using them also becomes expensive.

[0011] The object of the present invention is to provide a package that can prevent the opening from being curved and deformed due to moisture, heat, and tensile force when removing the contents, regardless of the material of the package. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent Publication No. 2020-75723 [Patent Document 2] Patent Publication No. 2020-200047 DISCLOSURE OF THE INVENTION [Means for solving the problem]

[0013] In order to solve the above problem, the invention described in claim 1 is a packaging body made of a synthetic resin film, wherein a front surface of the synthetic resin film on a planned opening line of the packaging body is film and the back film Heat-sealable Square shape from front and back Strip film Regarding the front and rear films Multiple heat-sealed sections Singular or plural Joined by heat fusion with non-heat fusion parts Ta It is characterized by the following.

[0014] In addition, the invention described in claim 2 is characterized in that, in the packaging body described in claim 1, the strip film is a laminate of three types of synthetic resin film, and the layer in contact with the contents and the layers in contact with the front and back of the synthetic resin film are made of unstretched film that can be heat-sealed, and the middle layer is made of stretched film.

[0015] Furthermore, the invention described in claim 3 is characterized in that the packaging body described in claim 1 or 2 is provided with an automatic steam release mechanism that automatically adjusts the pressure inside the packaging body when heated in a microwave oven.

[0016] Furthermore, the invention described in claim 4 is a packaging body described in any one of claims 1 to 3, characterized in that the packaging body is a self-standing bag in which a front film on the front side and a back film on the back side are arranged with their heat-sealable surfaces facing each other, and a bottom film is inserted at the bottom side of the packaging body with its heat-sealable surface facing the front film and back film, and both side ends of the packaging body and the bottom where the bottom film is inserted are heat-sealed.

[0017] Furthermore, the invention described in claim 5 is a packaging body described in any one of claims 1 to 3, characterized in that the packaging body is a two-pronged bag formed by forming a single synthetic resin film into a cylindrical shape and directly heat-sealing both ends of the synthetic resin film, or by inserting heat-sealable members into both ends of the synthetic resin film and heat-sealing them.

[0018] Furthermore, the invention described in claim 6 is characterized in that, in the packaging body described in any one of claims 1 to 3, the packaging body is a three-sided bag in which two synthetic resin films are arranged with their heat-sealable surfaces facing each other and heat-sealed on both side edges and either the top or bottom of the synthetic resin films. [Effects of the Invention]

[0019] According to the invention of claim 1, by joining the film constituting the packaging body and a separate, heat-sealable strip film on the intended opening line of the packaging body in a shape that provides multiple heat-sealed and non-heat-sealed sections, the film constituting the packaging body near the intended opening line is supported by the strip film, thereby preventing the opening opening from being curved or deformed by factors such as moisture, heat, and tensile stress.

[0020] The strip film is not limited in material or thickness as long as it is a synthetic resin film that can be heat-sealed to the film that constitutes the packaging body, and can be selected according to the sealant film of the packaging body and the intended use of the product.

[0021] Therefore, there are no restrictions on the material, thickness, or layer structure of the film that constitutes the packaging, and it can be applied to a wide variety of existing packaging made from synthetic resin films.

[0022] The shape of the heat seal that joins the film that constitutes the packaging body to the strip film can be various shapes such as those shown in Figure 1, but is not limited to these. Any shape in which the heat seal portion and the non-heat seal portion are arranged in a balanced manner can prevent the opening from curving and deforming.

[0023] By increasing the area of the strip film, it is possible to prevent greater bending deformation of the opening, but from the viewpoint of bag manufacturing suitability and the cost of the package, the width of the strip film in the height direction of the package is 12 mm to 40 mm, and more preferably 15 mm to 30 mm.

[0024] According to the invention of claim 2, by using a stretched film as the middle layer of the strip film, heat resistance is improved and bag manufacturing becomes easier. Furthermore, waviness due to thermal shrinkage of the film at the heat-sealed portion and resin leakage at the end of the package are suppressed, resulting in a neatly finished package.

[0025] Furthermore, by using a film that can be torn in a straight line along the manufacturing flow direction for the strip film, it can be torn in a straight line along the intended opening line that runs across the package.

[0026] For example, the above function can be achieved by incorporating a uniaxially oriented polyethylene film, oriented polyester film, oriented polyamide film, or polypropylene film, which has the property of being able to be torn in a straight line, as an intermediate layer, and laminating heat-sealable unoriented films on both sides of the intermediate layer.

[0027] By incorporating the film that can be torn in a straight line into the layer structure of the film that makes up the package, the same function as described above can be obtained, but since the expensive film that can be torn in a straight line is used for the entire package, using it for the strip film makes it possible to produce the package more cheaply.

[0028] According to the invention described in claim 3, by using the packaging of claim 1 or claim 2, which is equipped with a steam release mechanism that automatically adjusts the pressure inside the packaging when heated in a microwave oven, the contents can be heated in a microwave oven while still sealed and packaged, and bending and deformation of the opening can be prevented when the contents are opened after heating.

[0029] The intended opening line of the package is positioned below the automatic steam release mechanism, so that the strip film does not get caught on the automatic steam release mechanism, the automatic steam release operation is not adversely affected, and the automatic steam release mechanism does not interfere with opening.

[0030] According to the invention described in claim 4, two synthetic resin films that form the front and back of the packaging body are arranged with their heat-sealable surfaces facing each other, and a synthetic resin film that is folded with its heat-sealable surface facing outward is inserted into the bottom of the packaging body, and the opening of the self-standing bag that has been heat-sealed at both side edges and at the bottom where the folded film has been inserted can be given the function of preventing bending and deformation.

[0031] According to the invention described in claim 5, the opening of a two-sided bag formed by joining a single synthetic resin film into a cylindrical shape and then heat-sealing both ends of the synthetic resin film, either directly or by inserting a heat-sealable member to join both ends of the synthetic resin film, can be given the function of preventing bending deformation.

[0032] According to the invention described in claim 6, the opening of a three-sided bag in which two synthetic resin films are arranged with their heat-sealable surfaces facing each other and heat-sealed on both side edges and either the top or bottom can be given the function of preventing bending deformation. [Brief explanation of the drawings]

[0033] [Figure 1] (a) to (f) show the heat-sealed shapes for joining the synthetic resin film and the strip-shaped film that constitute the packaging body. [Figure 2](a) A front view of a self-standing bag in which a strip of film is inserted along the intended opening line in the heat-sealed shape of Fig. 1(a) used in Examples 1 to 3. (b) A back view of a self-standing bag in which a strip of film is inserted along the intended opening line in the heat-sealed shape of Fig. 1(a) used in Examples 1 to 3. [Figure 3] 1 shows a self-standing bag in which the entire surface of the strip film used in Examples 1 to 3 is heat-sealed. [Figure 4] This shows the self-standing bag without the strip-shaped film used in Examples 1 to 3. [Figure 5] FIG. 2 is a cross-sectional view of a film constituting the packaging body in Examples 1 to 3. [Figure 6] 1 is a cross-sectional view of a strip film in Examples 1 to 3. FIG. [Figure 7] 1 is a photograph showing a typical example of a sample in Examples 1 to 3 in which the opening opening is not curved or deformed. [Figure 8] 1 is a photograph showing a typical example of a sample in Examples 1 to 3 in which the opening opening was curved and the film edge was bent. [Figure 9] 1 is a photograph showing a typical example of a sample in Examples 1 to 3 in which the opening opening was significantly curved and deformed, with the film edge wrapping around. [Figure 10] This shows a two-sided pouch with a heat-sealed shape as shown in Figure 1(a) and a strip of film inserted along the intended opening line. [Figure 11] This shows a three-sided bag with a heat-sealed shape as shown in Figure 1(a) and a strip of film inserted along the intended opening line. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. [Example]

[0035] In Example 1, a packaging body made of materials intended for packaging cooked frozen foods that do not require a heat sterilization process when filling the contents is used, and the state of curvature and deformation of the opening when the target packaging body is opened after heating in a microwave oven is evaluated.

[0036] 1(a) to 1(f) show the shape of the heat seal that joins the synthetic resin film and the strip film 1 that constitute the packaging body of the present invention. These shapes are merely examples and do not limit the heat-sealed shapes according to the present invention.

[0037] As shown in Figure 2, the packaging form of the packaging body 4 is a self-standing bag formed by joining a front film 4a, a back film 4b, and a bottom film 4c folded and inserted into the bottom of the packaging body 4 at heat-sealed sections 5 on both side edges of the packaging body 4 and at a heat-sealed section 6 on the bottom of the packaging body, and a strip-shaped film 1 is inserted on the intended opening line 8 of the packaging body, and is joined to the heat-sealable surfaces (sealant surfaces) of the front film 4a and back film 4b of the packaging body 4 so that the intended opening line 8 and the non-heat-sealed sections 3 overlap in position, with linear heat-sealed sections 2 and non-heat-sealed sections 3 arranged alternately.

[0038] The dimensions of the packaging body 4 are 180 mm wide, 170 mm high, and a 50 mm folded width of the base, assuming that it can be filled and packaged with one portion of cooked food. The width of the strip film 1 in the height direction of the packaging body 4 is 30 mm. The position of the opening means 7 and the intended opening line 8 is set to 70 mm from the top end of the packaging body 4 because if they are positioned too high, the tensile force acting near the intended opening line 8 due to the volume expansion inside the packaging that occurs during microwave heating will be small, and conversely, if they are positioned too low, the intended opening line 8 will be too close to the contents.

[0039] As shown in FIG. 5(a), the layer structure of the package 4 used in Example 1 is as follows: reference numeral 11 denotes a 12 μm biaxially oriented polyethylene terephthalate film (hereinafter referred to as PET) having high heat resistance and dimensional stability as the base film of the outermost layer of the package; reference numeral 12 denotes a 30 μm linear low-density polyethylene (hereinafter referred to as LLDPE) having low-temperature heat fusion properties and high cold impact resistance as the sealant film; and these synthetic resin films are laminated by a dry lamination method using a urethane-based two-component curing adhesive 13.

[0040] The layer structure of the strip film 1 used in Example 1 is such that it must be heat-sealed to the packaging body 4 and also to each other, and is laminated by dry lamination from top to bottom as shown in Figure 6(a) as follows: LLDPE 30µm (reference number 12) / adhesive (reference number 13) / PET 12µm (reference number 11) / adhesive (reference number 13) / LLDPE 30µm (reference number 12). Note that it is more preferable to use a film that can be heat-sealed at a lower temperature for the LLDPE on the side that is heat-sealed to the packaging body 4 than the LLDPE on the opposite side, as this improves work efficiency in the bag-making process.

[0041] As a comparison for evaluation, a fully heat-sealed product 20 was produced, in which the full-surface heat-sealed portion 10 in the strip film joining the strip film 1 and the packaging body 4, as shown in Figure 3, had the same area as the strip film 1, and no non-heat-sealed portion 3 in the strip film.

[0042] In addition, a conventional product 30 not using the strip film 1 as shown in FIG. 4 was also produced with the same specifications.

[0043] 200 ml of water was sealed in each of the packaging body 4 (Fig. 2) of Example 1, the fully heat-sealed product 20 (Fig. 3), and the conventional product 30 (Fig. 4), and after heating in a microwave oven at 600 W for 3 minutes, the degree of curvature and deformation of the opening when the intended opening line 8 was cut using the opening means 7 was compared and verified.

[0044] To prevent the verification sample bag from bursting due to volume expansion inside the package when heated in a microwave oven, a cross-shaped cut 9 measuring 4 mm in height and 4 mm in width was made in the outer film 20 mm in height and 20 mm in width from the upper right corner to serve as a water vapor outlet, as an automatic steam release mechanism.

[0045] The verification results of the curvature deformation of the opening are shown in Table 1. [Table 1]

[0046] The degree of bending deformation of the opening of each bag is shown in Figures 7 to 9. In Table 1, the degree of bending deformation of the opening of each bag is marked with ◯ for the degree of bending deformation of the opening of each bag, △ for the degree of bending deformation of the opening of each bag, and × for the degree of bending deformation of the opening of each bag. If the degree of bending deformation of the opening of each bag is marked with ◯, it is considered that there is no bending deformation and the object of the present invention, which is to prevent bending deformation of the opening of each bag, has been achieved.

[0047] When microwave heating was performed under the above conditions, it was confirmed that the volume of the package expanded to its maximum due to the water vapor generated inside the package approximately 2 minutes and 15 seconds after heating began, and the water vapor was released through incision 9.

[0048] For approximately 45 seconds after that, steam, heat, and tensile force continued to act on the package, and after heating was completed, the package was opened by cutting along the intended opening line 8, which had been subjected to this load.When the opening was cooled by the outside air, it is thought that the shrinkage of the LLDPE film 12, the innermost layer of package 4, became greater than that of the PET film 11, the outermost layer, causing the package to bend and deform inward.

[0049] From Table 1, it was confirmed that the package 4 (FIG. 2) according to Example 1 was effective in preventing the occurrence of the above-mentioned curved deformation. In contrast, the fully heat-sealed product 20 (Fig. 3) is able to give rigidity to the film near the opening by heat sealing it to the strip film 1, which prevents the LLDPE film 12, the innermost layer of the packaging bag 4, from shrinking when cooled, and does not cause large deformation like the conventional product 30 (Fig. 4) shown in Fig. 9. However, some of the test sample bags were found to bend from the bottom of the strip film 1 toward the inside of the package. [Example]

[0050] In Example 2, a packaging body 4 (Fig. 2) according to Example 2, which is made of materials intended for packaging food that will be filled with contents and then boiled to undergo sterilization, a fully heat-sealed product 20 (Fig. 3), and a conventional product 30 (Fig. 4) are used to evaluate verification sample bags after boiling sterilization and verification sample bags that have been boiled sterilized and then heated in a microwave oven in the same manner as in Example 1.

[0051] As shown in FIG. 5(b), the layer structure of the package 4 used in Example 2 is such that reference numeral 14 denotes a 15 μm thick biaxially oriented nylon (hereinafter referred to as Ny) substrate film with high impact resistance as the outermost layer of the package, which is laminated with a 60 μm thick LLDPE sealant film (reference numeral 12) and an adhesive 13 by a dry lamination method.

[0052] The strip film 1 used in Example 2 was the same as that used in Example 1.

[0053] The cross-shaped cut 9 on the package 4 (FIG. 2) in Example 2 is not necessary for boiling sterilization, but is required for microwave heating, so it was made on the sample bag immediately before microwave heating after boiling sterilization. The shape and position of the cross-shaped cut 9 are the same as those in Example 1.

[0054] The boiling sterilization conditions were 90°C for 60 minutes, and assuming refrigerated distribution, the product was stored for 24 hours in an atmosphere of 5°C after boiling sterilization. The contents, microwave heating conditions, and evaluation method were the same as in Example 1.

[0055] Table 2 shows the verification results of the curvature deformation of the opening. [Table 2]

[0056] In the fully heat-sealed product 20 and conventional product 30 that were opened after boiling sterilization, the outermost Ny film 14 shrunk due to boiling sterilization, causing the bag to bend outward. We believe that the reason that the fully heat-sealed product 20 that was opened after microwave heating did not bend is because microwave heating was performed in a state in which the Ny film 14 had shrunk due to boiling sterilization, thereby achieving a balance with the shrinkage of the LLDPE film 12. On the other hand, in the conventional product 30 without the strip film 1, the rigidity of the opening was weak, so the shrinkage of the LLDPE film 12 due to microwave heating was greater than the shrinkage of the Ny film 14 due to boiling sterilization, resulting in a significant bending deformation towards the inside of the bag.

[0057] Example 2 The packaging body 4 relating to the present invention was able to prevent the opening from being curved or deformed by controlling the shrinkage of the Ny film 14 or LLDPE film 12 due to boiling sterilization and microwave heating by utilizing the difference in the degree of shrinkage between the heat-sealed portion 2 and the non-heat-sealed portion 3 on the strip film 1. [Example]

[0058] In Example 3, a packaging body 4 made of materials intended for use in retort sterilization is used, and evaluation sample bags after spray-type retort sterilization and evaluation sample bags after retort sterilization and microwave heating are evaluated in the same manner as in Examples 1 and 2.

[0059] As shown in Figure 5(c), the layer structure of the packaging body 4 used in Example 3 is such that reference numeral 15 is a highly heat-resistant unstretched polypropylene film (hereinafter referred to as CPP) used as a sealant film, and from the outermost layer of the packaging body, it is composed of PET 12 μm (reference numeral 11) / adhesive 13 / Ny (reference numeral 14) / adhesive 13 / CPP (reference numeral 15) 60 μm, and is laminated using the dry lamination method using adhesive 13.

[0060] The layer structure of the strip film 1 used in Example 3 corresponds to the packaging body 4 whose sealant film is CPP, and is layered from top to bottom as shown in Figure 6(b), with CPP 30 μm (symbol 15) / adhesive 13 / PET 12 μm (symbol 11) / adhesive 13 / CPP 30 μm (symbol 15), and is laminated using the dry lamination method using adhesive 13.

[0061] As in Example 2, the cross-shaped cut 9 on the package 4 (FIG. 2) of Example 3 is not necessary for retort sterilization, but is required for microwave heating, so it was made on the sample bag immediately before microwave heating after retort sterilization. The shape and position of the cross-shaped cut 9 are the same as in Examples 1 and 2.

[0062] The spray retort sterilization treatment conditions were 121°C for 30 minutes. The contents, microwave heating conditions, and evaluation method were the same as in Examples 1 and 2.

[0063] The verification results of the curvature deformation of the opening are shown in Table 3. [Table 3]

[0064] In Example 3, the outermost layer of the bag was made of a highly heat-resistant and water-resistant PET film 11, so the retort sterilization process did not result in the bag curving outward. However, in the fully heat-sealed product 20 and the conventional product 30, either or both of the Ny film 14 in the middle layer and the CPP film 15 in the innermost layer shrunk, causing the bag to curve inward. Similar results were also observed when the bags were opened after microwave heating. This is thought to be because the bags themselves have high rigidity and heat resistance, so they did not curve as significantly as in Examples 1 and 2.

[0065] It was confirmed that the product of the present invention is superior to the fully heat-sealed product 20 and the conventional product 30 in terms of material composition with high rigidity and heat resistance, which is expected for retort sterilization treatment.

[0066] In this embodiment, a self-standing bag is used as the packaging body into which the strip film is inserted, but the same effect can be achieved in other types of bags, such as a two-sided bag (Figure 10) or a three-sided bag (Figure 11), by joining the strip film 1 along the intended opening line 8 to the heat-sealable surfaces (sealant surfaces) of the front film 4a and back film 4b of the packaging body 4 in the shape illustrated in Figure 1. [Explanation of symbols]

[0067] 1 strip of film 2 Heat-sealed part in the strip film 3 Non-heat-sealed portion of the film strip 4 Packaging 4a Front film 4b Rear film 4c Bottom film 5 Heat-sealed parts on both ends 6 Heat-sealed part at the bottom of the package 7. Opening Method 8 Opening line 9 Cross notch (automatic steam release mechanism) 10 Full-surface heat-sealed parts 11 PET film 12 LLDPE film 13 Adhesive 14 Ny film 15 CPP film 20 Fully heat-fused product 30 Conventional product

Claims

1. A packaging body made of a synthetic resin film, characterized in that a strip film that is rectangular when viewed from the front and back and that can be heat-sealed to the front and back films of the synthetic resin film on the intended opening line of the packaging body is heat-sealed to the front and back films using multiple heat-sealed sections and one or more non-heat-sealed sections.

2. The packaging body described in claim 1, characterized in that the strip film is a laminate of three types of synthetic resin films, and the layer in contact with the contents and the layers in contact with the front and back of the synthetic resin film are made of unstretched film that can be heat-sealed, and the intermediate layer is made of stretched film.

3. 3. The package according to claim 1, further comprising an automatic steam release mechanism for automatically adjusting the pressure inside the package during microwave heating.

4. The packaging body described in any one of claims 1 to 3 is a self-standing bag in which a front film on the front side and a back film on the back side are arranged with their heat-sealable surfaces facing each other, a bottom film is inserted at the bottom side of the packaging body by folding the heat-sealable surface toward the front film and back film, and both side ends of the packaging body and the bottom where the bottom film is inserted are heat-sealed.

5. The packaging body according to any one of claims 1 to 3, characterized in that the packaging body is a two-sided bag formed by forming a single synthetic resin film into a cylindrical shape and directly heat-sealing both ends of the synthetic resin film, or by inserting heat-sealable members into both ends of the synthetic resin film and heat-sealing them.

6. The packaging body described in any one of claims 1 to 3 is a three-sided bag in which two synthetic resin films are arranged with their heat-sealable surfaces facing each other and heat-sealed on both side edges and either the top or bottom of the synthetic resin films.

Images