Film, packaging body, and packaging body containing contents

Abstract

A film (11), which is used in a package (1) in which the internal pressure of a container is increased by heating with a microwave oven and the internal pressure is reduced by discharging internal vapor, is provided with: an outer layer film (21) that has been molecularly oriented by biaxial stretching; an inner layer film (22) which is laminated on the outer layer film (21) and can be thermally fused; one or more orientation relaxation sections (21a) that are formed on the outer layer film (21); and a broken section (13) that is formed at a location where the one or more orientation relaxation sections (21a) face each other with a predetermined interval therebetween, that is broken by an increase in the internal pressure of the container by the microwave oven, and that does not have a printed layer between the outer layer film (21) and the inner layer film (23) at least in the broken section (13).

Description

Technical Field

[0001] The present invention relates to a film, a packaging body and a packaging body containing the contents, which discharge steam generated when the contents of the packaging are heated by a microwave oven to the outside. Background Art

[0002] Conventionally, there are known packages that heat the contents in a microwave oven while the contents are contained and sealed. However, when the contents are heated in a microwave oven, the internal pressure of such packages increases. Therefore, there are also known packages that have a component that automatically discharges steam and reduces the internal pressure during microwave heating.

[0003] For example, Japanese Patent Application Publication No. 2019-64642 discloses a package and a film that can release water vapor during microwave heating by providing a broken portion having a non-oriented portion disposed opposite to an oriented portion sandwiching a crystalline stretched oriented film.

[0004] In addition, for example, Japanese Patent Application Publication No. 2017-74965 discloses a packaging body and a film that can be steamed without excessively releasing water vapor.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-64642

[0008] Patent Document 2: Japanese Patent Application Publication No. 2017-74965 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In the above-mentioned technology, there is a case where the internal pressure rises excessively and the bag breaks because the broken part does not break and the water vapor is not released. In particular, if a printed layer is provided between the outer film and the inner film in the film constituting the container, the adhesion between the outer film and the inner film is weakened and interlayer delamination occurs. If interlayer delamination occurs, stress will not be concentrated on the broken part of the film, the broken part will not break, and the internal pressure of the container will rise excessively and the bag will break.

[0011] The present invention can provide a film, a package, and a package containing contents that can stably discharge water vapor.

[0012] Means for solving problems

[0013] A film in one form of the present invention is used for a packaging body, which is heated by a microwave oven to increase the internal pressure of the container, and discharge the internal steam to reduce the internal pressure, wherein the film comprises: an outer film, which is molecularly oriented by biaxial stretching; an inner film, which is laminated on the outer film and can be heat-welded; one or more orientation relaxation sections, which are formed on the outer film; and a breaking section, which is formed at locations where the one or more orientation relaxation sections are opposite to each other at a predetermined interval, and is broken by the increase in the internal pressure of the container due to the microwave oven, and at least in the breaking section, there is no printed layer between the outer film and the inner film.

[0014] Effects of the Invention

[0015] The present invention can provide a microwave heating container, a film and a microwave heating container containing contents which can stably discharge steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a perspective view showing the structure of the package according to the first embodiment of the present invention.

[0017] Figure 2 It is a plan view showing an example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0018] Figure 3 is Figure 2 A cross-sectional view of the layer structure of the film used for the packaging body is shown at the III-III line section in FIG.

[0019] Figure 4 This is a perspective view showing a state after heating in a microwave oven as an example of using the package body.

[0020] Figure 5 It is a plan view showing an example of the structure of an orientation relaxation portion and a breaking portion provided in the package body.

[0021] Figure 6 It is a plan view showing another example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0022] Figure 7 It is a plan view showing another example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0023] Figure 8 It is a plan view showing another example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0024] Fig. 9It is a plan view showing another example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0025] Fig.10 It is a plan view showing another example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0026] Fig.11 It is a plan view showing another example of the structure of three or more orientation relaxing portions and breaking portions provided in the package body.

[0027] Fig.12 It is a plan view showing another example of the structure of three or more orientation relaxing portions and breaking portions provided in the package body.

[0028] Fig.13 It is a plan view showing another example of the structure of three or more orientation relaxing portions and breaking portions provided in the package body.

[0029] Fig.14 It is a perspective view showing the structure of a package according to a second embodiment of the present invention.

[0030] Fig.15 It is a cross-sectional view schematically showing the layer structure of a film used for a packaging body according to a third embodiment of the present invention.

[0031] Fig.16 It is a cross-sectional view schematically showing the layer structure of a film used for a packaging body according to a fourth embodiment of the present invention.

[0032] Fig.17 It is a perspective view showing the structure of the package.

[0033] Fig.18 It is a cross-sectional view schematically showing the layer structure of a film used for a packaging body according to a fifth embodiment of the present invention.

[0034] Fig.19 It is a cross-sectional view schematically showing the layer structure of a film used for a packaging body according to a sixth embodiment of the present invention.

[0035] Fig. 20 It is a cross-sectional view schematically showing the layer structure of a film used for a packaging body according to a seventh embodiment of the present invention.

[0036] Fig.21 It is a perspective view showing the structure of a package according to an eighth embodiment of the present invention.

[0037] Fig. 22 It is a perspective view showing the structure of a package according to a ninth embodiment of the present invention.

[0038] Fig.23It is a perspective view showing the structure of the package.

[0039] Fig.24 It is a cross-sectional view schematically showing the layer structure of a film used for a packaging body according to a tenth embodiment of the present invention.

[0040] Fig.25 It is a plan view showing an example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body.

[0041] Fig.26 It is a plan view showing an example of the structure of a pair of orientation relaxing portions and a breaking portion provided in the package body according to the eleventh embodiment of the present invention. DETAILED DESCRIPTION

[0042] use Figures 1 to 13 , a packaging body 1 using the film 11 according to the first embodiment of the present invention will be described.

[0043] Figure 1 1 is a perspective view showing the structure of a package body 1 according to an embodiment of the present invention. Figure 2 1 is a plan view showing an example of the structure of a pair of orientation relaxing portions 21a and a breaking portion 13 provided in the package body 1. Figure 3 It is a cross-sectional view schematically showing the layer structure of the film 11 used in the packaging body 1. Figure 4 This is a perspective view showing a state after heating in a microwave oven as an example of the use of the package body 1.

[0044] The package 1 is a packaging container that packages the content 200 inside. The package 1 is a microwave heating container that can be heated by a microwave oven and accommodates the content 200. Figure 1 As shown, in this embodiment, the package body 1 is a package body formed into a bag shape by forming a film 11, and the film 11 has a multi-layer structure having a biaxially stretched oriented film 21 on the outer surface side. The package body 1 is, for example, a pillow-type packaging bag in which the content 200 is contained in the film 11 formed into a bag shape and the ends are sealed by using a sealing portion 12.

[0045] As a specific example, the package 1 includes: a laminated film 11 having a biaxially stretched oriented film 21 on the outer surface side; a sealing portion 12 formed by forming the film 11 into a bag shape and welding the ends; and a breaking portion 13 provided on the film 11 and breaking when the internal pressure rises. Here, the content 200 refers to items heated by a microwave oven and containing water, such as food cooked by microwave oven heating and wet wipes heated by microwave oven.

[0046] The film 11 is used to form at least a part of the packaging material of the package body 1. The film 11 is configured, for example, to be in a rectangular shape that can be formed into a bag shape. The layer structure of the film 11 includes a biaxially stretched oriented film 21, an adhesive layer 22, and a sealant film 23 from the outer surface side of the package body 1 when the package body 1 is formed. In addition, the film 11 may also include a printed layer 24 between the biaxially stretched oriented film 21 and the sealant film 23. In addition, the film 11 may also include a printed layer 24 on the outer surface of the biaxially stretched oriented film 21. In addition, the layer structure of the film 11 is not limited to this, as long as it has two or more layers and at least one layer has a biaxially stretched oriented film 21.

[0047] The biaxially stretched oriented film 21 includes an orientation relaxation section 21a formed by heating a portion to a predetermined temperature near the melting point or higher. The orientation relaxation section 21a constitutes a portion of the breaking section 13. The orientation relaxation section 21a is configured in various shapes depending on the structure of the breaking section 13.

[0048] The biaxially stretched oriented film 21 is a crystalline stretched oriented film. The biaxially stretched oriented film 21 is composed of, for example, general biaxially stretched films such as biaxially stretched PET film, biaxially stretched nylon film, biaxially stretched PP film, or composite films thereof. In addition, as other preferred examples, the biaxially stretched oriented film 21 can include biaxially stretched films with barrier properties such as biaxially stretched PVA film and biaxially stretched EVOH film, and co-extruded biaxially stretched films such as PP / EVOH / PP, NY / EVOH / NY, NY / MXD-NY / NY, etc., which have barrier resins in the middle layer. In addition, films formed by coating PVA-based, PVDC-based, PAA-based barrier resins on general biaxially stretched films, or composite coated films formed by dispersing inorganic substances in the aforementioned barrier resins, can also be appropriately used for the biaxially stretched oriented film 21. The thickness of the biaxially stretched oriented film 21 is preferably greater than 12 μm and less than 50 μm.

[0049] This is because, if the thickness of the biaxially stretched oriented film 21 is less than 12 μm, the physical strength of the package 1 may be reduced, and there are difficulties in film forming technology, which will increase the cost. In addition, this is because, if the thickness of the biaxially stretched oriented film 21 exceeds 50 μm, the film 11 including the biaxially stretched oriented film 21 is difficult to stretch. However, as long as the structure is such that the breaking portion 13 is broken according to the shape of the orientation relaxation portion 21a, the thickness of the biaxially stretched oriented film 21 is not limited.

[0050] The orientation relaxation section 21a is formed by heating the biaxially stretched oriented film 21 to a predetermined temperature near the melting point or above and relaxing the orientation or eliminating the orientation. That is, the biaxially stretched oriented film 21 of the film 11 has an orientation relaxation section 21a heated to a predetermined temperature near the melting point or above in a part of the orientation section 21b that is not heated to a predetermined temperature near the melting point and has an orientation. In addition, although the predetermined temperature near the melting point is different depending on the biaxially stretched oriented film 21, it is at least a temperature that can relax the orientation and make the tensile elastic modulus and elongation at break of the orientation relaxation section 21a and the orientation section 21b have a desired relationship.

[0051] Here, when the tensile elastic modulus in the molecular orientation portion of the film 11 is set to E1 and the tensile elastic modulus in the molecular orientation relaxation portion is set to E2, the relationship between the tensile elastic modulus E1 of the orientation portion 21b and the tensile elastic modulus E2 of the orientation relaxation portion 21a is, for example, 0<E2 / E1<0.5. The molecular orientation portion of the film 11 refers to a portion of the film 11 having the biaxially stretched oriented film 21, the adhesive layer 22 and the sealant film 23 where the orientation portion 21b of the biaxially stretched oriented film 21 exists, and the molecular orientation relaxation portion of the film 11 refers to a portion of the film 11 where the orientation relaxation portion 21a of the biaxially stretched oriented film 21 exists.

[0052] For example, when the biaxially stretched oriented film 21 of the present embodiment is a biaxially stretched PET film, the tensile elastic modulus E1 of the molecular orientation portion of the film 11 is approximately 2000 MPa, and the tensile elastic modulus E2 of the molecular orientation relaxation portion is approximately 200 MPa. In this case, E2 / E1 is approximately 0.1, which is a value less than 0.5.

[0053] As a heating method for the biaxially stretched oriented film 21 for forming the orientation relaxing portion 21 a in the biaxially stretched oriented film 21 , it is preferable to use a method such as laser heating, hot plate heating, pulse heating, near infrared heating, or the like.

[0054] For example, laser heating and near infrared heating have the advantage of being able to heat the biaxially stretched oriented film 21 in a non-contact manner, but laser heating is preferred because it can be heated locally. In addition, when the biaxially stretched oriented film 21 used lacks absorptivity to laser and is difficult to form the orientation relaxation portion 21a, a laser absorbing material that improves the absorptivity of the biaxially stretched oriented film 21 to the laser may be mixed in advance with the material of the stretched oriented film 21, or the biaxially stretched oriented film 21 may be coated with a laser absorbing material.

[0055] In addition, as the type of laser, it is preferred to use a carbon dioxide laser whose absorption is relatively high in most of the resin raw materials used in the biaxially stretched oriented film 21. As a laser absorbing material, it can be appropriately selected according to the type of laser. These heating methods can be appropriately selected according to the material of the biaxially stretched oriented film 21 used, etc.

[0056] In the case of hot plate heating or pulse heating, the pressing head is preferably subjected to Teflon (registered trademark) surface treatment or the like to prevent the melted resin of the biaxially stretched oriented film 21 and a part of the resin of the sealant film 23 from being attached to the pressing head. For example, in the case of hot plate heating, a pressing head (hot plate) whose temperature is set to a predetermined temperature or higher near the melting point of the biaxially stretched oriented film 21 and is heated is pressed on the biaxially stretched oriented film 21 and melt-heated, thereby forming the orientation relaxation portion 21a.

[0057] In addition, whether the formed orientation relaxation portion 21a has been properly formed can be determined by inspecting the formed biaxially stretched oriented film 21. As the inspection method, crystallinity measurement using X-ray diffraction, FT-IR (Fourier transform infrared spectroscopy), DSC (differential scanning calorimetry), etc., an orientation observer using a polarizing plate, etc. can be used.

[0058] Such a biaxially stretched oriented film 21 has, for example, an elongation at break of the oriented portion 21 b set to 200% or less, and an elongation at break of the orientation relaxation portion 21 a set to 300% or more.

[0059] The adhesive layer 22 can be appropriately selected from general dry lamination adhesives for food use and used. However, since the package 1 is used for microwave heating, the adhesive layer 22 preferably has heat resistance. From the perspective of performance and economy, the thickness of the adhesive layer 22 is more preferably 2 μm to 5 μm.

[0060] The sealant film 23 is composed of, for example, an unstretched low-density polyethylene (LDPE) film, an unstretched linear low-density polyethylene (LLDPE) film, an unstretched polypropylene (PP) film, an unstretched polyethylene terephthalate film, etc. The thickness of the sealant film 23 is preferably 10 μm or more and 100 μm or less. In addition, the thickness of the sealant film 23 is more preferably 20 μm or more and 60 μm or less.

[0061] This is because, when the thickness of the sealant film 23 is less than 10 μm, the actual strength of the package 1 may be insufficient, and the seal portion 12 may be easily broken due to vibration during transportation or impact from falling. In addition, if the thickness of the sealant film 23 exceeds 100 μm, it becomes difficult to stretch, and therefore, there may be a problem with the reliability of steam discharge.

[0062] The printed layer 24 is provided on a portion of the film 11 or is not provided on a portion of the film 11 at least in the region of the break portion 13. In other words, the printed layer 24 is provided in a region where the oriented portion 21b between the orientation relaxing portions 21a constituting the break portion 13 is provided and other than between the biaxially stretched oriented film 21 and the adhesive layer 22 or between the adhesive layer 22 and the sealant film 23.

[0063] As a specific example, Figure 3 As shown, the printing layer 24 is provided between the biaxially stretched oriented film 21 and the sealant film 23 except for the region provided with the break portion 13. For example, the printing layer 24 is provided between the biaxially stretched oriented film 21 and the adhesive layer 22 except for the orientation portion 21b between the two orientation relaxation portions 21a of the biaxially stretched oriented film 21, i.e., the break portion 13.

[0064] The seal portion 12 is formed by heat-sealing (heat-fusion bonding) the film 11 at the end portion.

[0065] The breaking portion 13 is formed by the oriented portion 21b disposed between the orientation relaxing portions 21a facing each other. That is, the breaking portion 13 is provided on a part of the film 11, extends in a straight line or a curve, and is formed by disposing a single orientation relaxing portion 21a of a shape in which two parts of the film 11 face each other at a predetermined interval, or by disposing a plurality of orientation relaxing portions 21a facing each other, thereby utilizing the oriented portion 21b existing between the orientation relaxing portions 21a. That is, the breaking portion 13 is formed by sandwiching a part of the orientation relaxing portion 21a with the oriented portion 21b of the biaxially stretched oriented film 21 that is not heated to a predetermined temperature above the melting point, in other words, sandwiching the oriented portion 21b of the biaxially stretched oriented film 21 having an orientation.

[0066] As a specific example, Figure 2 , Figure 5 to Figure 13 As shown in FIG. 1 , the alignment relaxation section 21a has a short side and a long side, and is provided with more than one. When one alignment relaxation section 21a is provided, as shown in FIG. Figure 5 As shown, the orientation relaxing section 21 a has its short sides facing each other with a predetermined interval therebetween, or has its short side and long side facing each other with a predetermined interval therebetween.

[0067] When two alignment relaxation portions 21a are provided, the two alignment relaxation portions 21a are as follows: Figure 2 , Figure 6 to Figure 8 As shown, the respective short sides are spaced apart from each other and face each other at a predetermined interval, or as shown Fig. 9 and Fig.10As shown in FIG. 1 , the short side of one alignment relaxation section 21a and the long side of the other alignment relaxation section 21a are arranged to face each other at a predetermined interval. Similarly, when three or more alignment relaxation sections 21a are provided, as shown in FIG. Figure 11 to Figure 13 As shown, any two or more orientation relaxing portions 21a or three or more orientation relaxing portions 21a face each other with short sides or with long sides separated by a predetermined interval. In addition, when a plurality of orientation relaxing portions 21a are provided in the break portion 13, it is preferred that Figure 2 As shown, the size and shape of the orientation relaxation portion 21a are the same, but as long as the structure of the broken portion 13 is broken, it can also be as shown in Fig.13 As shown, they are provided in different sizes and shapes.

[0068] More specifically, the breaking portion 13 is formed by making one or more orientation relaxation portions 21a obtained by heating the biaxially stretched oriented film 21 sandwich the oriented portion 21b with orientation of the biaxially stretched oriented film 21 at a predetermined distance and spaced apart. Here, the predetermined distance can be set appropriately as long as it can break the breaking portion 13 and form a steam port 21c when heated in a microwave oven, but is preferably less than 5mm. In addition, the long side and the short side are not limited to a straight line, and can also be a curved line. That is, the breaking portion 13 can be formed as long as the orientation relaxation portion 21a extends in any direction and one end of an orientation relaxation portion 21a is spaced apart from other parts of the orientation relaxation portion 21a or a part of the other orientation relaxation portion 21a at a predetermined interval. In addition, as long as the breaking portion 13 can be broken and a steam port 21c can be formed, a part of the orientation portion 21b sandwiched between the opposing orientation relaxation portions 21a can also be oriented and relaxed.

[0069] In addition, as for the shape of one orientation relaxation section 21a, the following can be considered: Figure 5 As shown in the figure, a partially missing circular ring, a polygonal ring, etc. For the two orientation relaxation portions 21a, for example, it can be considered as follows Figure 2 , Figure 6 and Figure 7 As shown in the figure, the short sides are arranged to face each other in a straight line or at a predetermined angle, as shown in the figure. Fig. 9 and Fig.10 As shown in the figure, the short side and the long side are arranged to face each other in a T-shape. In addition, for the two orientation relaxation portions 21a, in addition to the straight line shape, it is also possible to consider the following Figure 8 As shown in the figure, it is set to a wavy structure. In addition, as three or more orientation relaxation sections 21a, it is conceivable to Fig.12 and Fig.13 As shown in the figure, the structure in which the long side is arranged in one direction, Fig.11As shown, the structure is arranged in the circumferential direction with the fracture portion 13 as the center.

[0070] In addition, for the orientation relaxation section 21a, if the manufacturing cost etc. are taken into consideration, Figure 2 As shown, the following structure is preferred: the orientation relaxation section 21a is formed into a rectangular shape that is long in one direction, and is provided in pair, with the short sides facing each other. Figure 2 The orientation relaxation section 21a shown preferably has a short side length of 0.5 to 10 mm and a long side length of 3 to 100 mm, and the short side length is set to be shorter than the long side length, which can be appropriately selected according to the size of the bag and the structure of the laminate. In addition, the distance between the opposing short sides of the two orientation relaxation sections 21a is set to be less than 5 mm, and more preferably set to 0.5 to 3.0 mm, which can be appropriately selected according to the size of the bag and the structure of the laminate.

[0071] This is because, when the size of the orientation relaxation section 21a is smaller than this range, the extension range may become too narrow to start the steam discharge smoothly. If it exceeds this range, the strength of the bag is reduced and the effect of reducing the gas barrier property may become greater. In addition, this is because, when the distance between the opposing short sides of the two orientation relaxation sections 21a is smaller than this range, the front ends of the opposing orientation relaxation sections 21a may be integrated with each other and fail to form the steam port 21c and break. In addition, if it exceeds this range, the area between the opposing short sides of the two orientation relaxation sections 21a cannot be extended, so the rupture section 13 may not break, and the package body 1 may fail to form the steam port 21c and break.

[0072] Next, a method for producing such a package 1 will be described.

[0073] First, a portion of the film 11 is heated to a predetermined temperature or higher near the melting point of the biaxially stretched oriented film 21, so that the orientation of a portion of the biaxially stretched oriented film 21 disappears and an orientation relaxation portion 21a of a predetermined shape is formed. As a specific example, a laser such as a carbon dioxide laser is irradiated to a portion of the film 11 at an output power of more than a predetermined temperature near the melting point of the biaxially stretched oriented film 21.

[0074] Next, the laser is scanned in the shape of the orientation relaxation section 21a to be formed. For example, in the case of forming a pair of orientation relaxation sections 21a, the laser is scanned in the shape of the orientation relaxation section 21a on one side, and then the laser irradiation is stopped, and the laser is irradiated again at the position where the orientation relaxation section 21a of the other side is formed. Next, the laser is scanned in the shape of the orientation relaxation section 21a on the other side. In addition, at this time, the orientation relaxation section 21a only needs to relax the orientation, and there is no need to irradiate the laser until it becomes non-oriented in which the orientation disappears, but it can also be non-oriented. Through these steps, a portion of the film 11 is heated to form the orientation relaxation section 21a. In this way, a film 11 with a break 13 formed in a portion is manufactured.

[0075] The film 11 formed in this way is formed into a bag shape, and the content 200 is arranged inside the bag. Next, the ends of the film 11 are heat-sealed to form the sealing portion 12, thereby manufacturing a bag-shaped package body 1 (a container for microwave heating containing the content) that contains the content 200 and is sealed. In addition, as long as the manufacturing method is that the package body 1 can contain the content 200 inside, for example, it can be that after heat-sealing except for a part to form a bag shape with a part opening, the content 200 is filled and the opening is heat-sealed, or it can be that after the content 200 is arranged on the film 11, it is formed into a bag shape and heat-sealed.

[0076] Next, a method of using such a package 1 will be described.

[0077] The package 1 containing the content 200 is placed in a microwave oven, and then the content 200 is heated by the microwave oven. When the content 200 is heated by the microwave oven, water vapor is generated from the content 200 and the internal pressure rises, the package 1 expands, and the film 11 stretches. When the film 11 stretches, the fractured portion 13 between the opposing short sides of the orientation relaxation portion 21a or between the opposing short sides and the long sides will break, and the steam of the package 1 escapes to the outside and the internal pressure is reduced, and the steam is discharged. In addition, the steam generated from the content 200 may also include alcohol vapor.

[0078] The function of the breaking portion 13 to discharge steam from the package body 1 is specifically described. When the package body 1 containing the content 200 containing water is heated by a microwave oven, water vapor is generated from the content 200 and the internal pressure rises, resulting in the expansion of the package body 1. At this time, the LDPE, LLDPE, CPP, etc. used in the sealant film 23 are generally not stretched, that is, not oriented, and therefore, compared with the stretched film, the tensile strength is lower and the elongation at break is also higher. On the other hand, the biaxially stretched oriented film 21 is generally higher in tensile strength and the elongation at break is also lower, so the film 11 formed by bonding the biaxially stretched oriented film 21 and the sealant film 23 is difficult to stretch.

[0079] However, since the orientation relaxation section 21a of the biaxially stretched oriented film 21 is a region where the orientation of the biaxially stretched oriented film 21 is relaxed or in a non-oriented state, the tensile strength is lower than that of the orientation section 21b, i.e., the orientation region, of the biaxially stretched oriented film 21. In addition, the tensile elastic modulus E2 of the molecular orientation relaxation section of the film 11 is lower than the tensile elastic modulus E1 of the molecular orientation section. Furthermore, when the internal pressure rises and the package 1 expands and the film 11 stretches, the film 11 in the region of the orientation relaxation section 21a stretches in the width direction due to stress concentration.

[0080] At this time, the film 11 in the region of the orientation part 21b located between the opposite short sides of the orientation relaxation part 21a or between the opposite short sides and the long sides also extends following the extension of the region of the orientation relaxation part 21a, but the value of the elongation at break of the region of the orientation relaxation part 21a is high and the tensile modulus is low. As a result, when the film 11 is extended to a certain extent, the region including the orientation part 21b located between the opposite short sides of the orientation relaxation part 21a or between the opposite short sides and the long sides, i.e., the fracture part 13, will be broken earlier than other parts of the film 11 due to the difference in elongation at break and tensile modulus between the orientation relaxation part 21a and the orientation part 21b, and a small hole for discharging water vapor will be generated. The small hole is used as the steam port 21c to discharge steam from the package body 1.

[0081] Furthermore, even if the film 11 has the printed layer 24, only the adhesive layer 22 is provided between the biaxially stretched oriented film 21 and the sealant film 23 at least in the region of the break 13, and the printed layer 24 is not provided between the biaxially stretched oriented film 21 and the sealant film 23. Therefore, since high adhesion is ensured between the biaxially stretched oriented film 21 as the outer layer film and the sealant film 23 as the inner layer film by the adhesive layer 22, even if the internal pressure of the package 1 increases, interlayer delamination between the biaxially stretched oriented film 21 and the sealant film 23 at the break 13 can be prevented.

[0082] That is, if the printed layer 24 is present between the biaxially stretched oriented film 21 and the sealant film 23, the adhesion between the biaxially stretched oriented film 21 and the sealant film 23 is reduced, and interlayer delamination is likely to occur.

[0083] However, the film 11 of the embodiment does not have the printed layer 24 between the biaxially stretched oriented film 21 and the sealant film 23 at least at the break 13. Therefore, the film 11 of the embodiment can properly obtain the close contact between the biaxially stretched oriented film 21 and the sealant film 23 at the break 13, and can prevent the occurrence of interlayer peeling, so that stress concentration is generated at the boundary of the molecular orientation part (break 13, orientation part 21b) between the molecular orientation relaxation part (orientation relaxation part 21a) and the adjacent molecular orientation relaxation part (orientation relaxation part 21a), and the biaxially stretched oriented film 21 and the sealant film 23 are properly broken at the break 13. Therefore, the package body 1 can prevent the so-called bag breakage in which the break 13 is not broken but the parts other than the break 13 are broken.

[0084] According to the package body 1 thus constructed, the rupture portion 13 is formed by placing the oriented portion 21b of a predetermined width between the short sides of the orientation relaxation portion 21a or between the short side and the long side on the film 11, and no printed layer 24 is provided between the biaxially stretched oriented film 21 and the sealant film 23 at the rupture portion 13. Therefore, the package body 1 can rupture the rupture portion 13 and discharge the steam inside when heated in a microwave oven.

[0085] According to the packaging body 1 and film 11 of the above embodiment, by configuring the printed layer 24 not to be provided between the biaxially stretched oriented film 21 and the sealant film 23 at the breaking portion 13, it is possible to prevent interlayer delamination of the film 11 at the breaking portion 13, and to enable stable discharge of steam during microwave heating.

[0086] In addition, the present invention is not limited to the above-mentioned embodiment. In the above-mentioned example, as an example of a structure in which the printed layer 24 is not provided between the biaxially stretched oriented film 21 and the sealant film 23 at the break 13 of the film 11 of the package body 1, a structure in which the printed layer 24 is provided between the biaxially stretched oriented film 21 and the sealant film 23 except for the region in which the break 13 is provided, and as a specific example, between the biaxially stretched oriented film 21 and the adhesive layer 22 is described, but the present invention is not limited to this.

[0087] Hereinafter, other embodiments of the film 11 of the package body 1 will be described. In addition, in each of the following examples, since the presence or absence of the printed layer 24 or the position of the printed layer 24 is different from that of the film 11 of the above-mentioned embodiment, the same reference numerals are given to the same structure and the detailed description of the structure is omitted. In addition, the film 11 of each of the following examples is a structure in which the printed layer 24 is not provided at least between the biaxially stretched oriented film 21 and the sealant film 23 at the break 13, so that interlayer delamination between the outer film (biaxially stretched oriented film 21) and the inner film (sealant film 23) at the break 13 can be prevented.

[0088] like Fig.14 As in the second embodiment shown, the film 11 of the package body 1 may be configured without the printed layer 24. That is, the film 11 may be configured by the biaxially oriented film 21, the adhesive layer 22, and the sealant film 23.

[0089] In addition, if Fig.15 As in the third embodiment shown in FIG. 1 , the film 11 of the package body 1 may be configured such that at least the printed layer 24 is provided on the outer surface of the biaxially stretched oriented film 21 and both the orientation relaxation portion 21a and the oriented portion 21b including the break portion 13. In addition, the printed layer 24 may be provided over the entire surface of the oriented portion 21b, that is, the entire surface of the film 11, or may be configured such that the printed layer 24 is not provided on a part of the oriented portion 21b.

[0090] In addition, if Fig.16 and Fig.17 As in the fourth embodiment shown in FIG. 1 , the film 11 of the package 1 may be configured such that the printed layer 24 is provided on the outer surface of the biaxially stretched oriented film 21, and is not provided in the region where the orientation relaxing portion 21a and the break portion 13 are provided, but is provided in the oriented portion 21b other than the orientation relaxing portion 21a and the break portion 13. Such a printed layer 24 may be configured to be provided in the entire region of the oriented portion 21b other than the orientation relaxing portion 21a and the break portion 13, and further, for example, Fig.17 As shown, the structure may be such that the polarizing element is provided in a region other than a predetermined region including the orientation relaxing portion 21 a and the breaking portion 13 , for example, in a region other than the region around the orientation relaxing portion 21 a and the breaking portion 13 .

[0091] In addition, if Fig.18As shown in the fifth embodiment, the film 11 of the packaging body 1 may also be configured such that a printed layer 24 is provided on the outer surface of the biaxially stretched oriented film 21, and a protective film 25 is further provided on the outer surface of the printed layer 24. That is, the film 11 may also be configured to have a multilayer structure having a biaxially stretched oriented film 21, an adhesive layer 22, a sealant film 23, a printed layer 24 and a protective film 25. For example, such a protective film 25 may be formed of the above-mentioned materials used for the biaxially stretched oriented film 21 and the sealant film 23, or may be formed of other materials. In addition, the printed layer 24 may be provided on the entire surface of the biaxially stretched oriented film 21, or may be provided avoiding the break portion 13, or may be provided avoiding the orientation relaxation portion 21a and the break portion 13, or may be provided on the entire surface except for any part. In Fig.18 In the example of FIG. 1 , the printed layer 24 is arranged to avoid the broken portion 13. Fig.18 As shown in the figure, the protective film 25 is not provided at least on the break portion 13, but is provided on the outer surface side of the biaxially stretched oriented film 21 avoiding the break portion 13. In addition, the protective film 25 may be configured to be provided avoiding the orientation relaxation portion 21a and the break portion 13, or may be configured to be provided avoiding the orientation relaxation portion 21a, the break portion 13, and the surroundings of the orientation relaxation portion 21a and the break portion 13.

[0092] In addition, if Fig.19 As in the sixth embodiment shown, the film 11 of the package 1 may be configured such that a printed layer 24 is provided on the outer surface side of the biaxially oriented film 21 and in a region excluding the break portion 13 .

[0093] In addition, if Fig. 20 As shown in the seventh embodiment, the film 11 of the packaging body 1 can also be constructed by arranging the printed layer 24 between the biaxially stretched oriented film 21 and the sealant film 23 except for the area where the breaking portion 13 and the orientation relaxation portion 21a are provided. As a specific example, it is arranged between the biaxially stretched oriented film 21 and the adhesive layer 22.

[0094] In addition, as another example, the film 11 of the packaging body 1 only needs to be constructed so that it is not arranged between the biaxially stretched oriented film 21 and the sealant film 23 at least at the break portion 13, and can also be constructed so that a printed layer 24 is provided on both the outer surface of the biaxially stretched oriented film 21 and between the biaxially stretched oriented film 21 and the sealant film 23.

[0095] In addition, the package 1 is not limited to the above-mentioned embodiments. For example, in the above-mentioned example, the structure in which the breaking portion 13 and one or more orientation relaxation portions 21a constituting the breaking portion 13 are provided on the film 11 is described, but it is not limited to this. Fig.21As in the eighth embodiment shown, the film 11 may not have the breaking portion 13 and the orientation relaxation portion 21a, but may have an opening 11a in a portion, and the packaging body 1 may be formed by welding a film sheet 14 that blocks the opening 11a and has the breaking portion 13 and one or more orientation relaxation portions 21a constituting the breaking portion 13 to the opening 11a.

[0096] In addition, in the above example, the packaging body 1 is described as an example of a bag-shaped packaging body, but it is not limited to this. Fig. 22 and Fig.23 As shown in the ninth embodiment of the present invention, the package 1A may be configured to include a bottomed cylindrical resin container 15 and a cover 16 covering the opening of the resin container 15, and the film 11 may be used in the cover 16. That is, the package 1A may use the film 11 provided with the breakable portion 13 in the cover covering the opening of the resin container 15.

[0097] The resin container 15 is formed into a bottomed cylindrical shape, for example, in a rectangular truncated cone, a polygonal truncated cone, or a circular truncated cone, and has a flange portion 15a at the opening. The cover 16 is bonded to the flange portion 15a of the resin container 15 containing the content 200 by heat sealing. The cover 16 is formed of a film 11 formed into an outer shape of the flange portion 15a, and a break portion 13 is arranged in the center.

[0098] The package 1A thus constructed can produce the same effects as the package 1 described above.

[0099] In the above example, the film 11 is heated by laser to form the orientation relaxation section 21a in the biaxially stretched oriented film 21. However, for example, Fig.24 and Fig.25 As shown in the film 11B of the tenth embodiment, in order to form the orientation relaxation section 21a, it is also possible to construct a laser absorption section 26 in a part of the film 11B. For example, the laser absorption section 26 is a portion of the film 11B that has a high absorption of the irradiated laser. For example, the laser absorption section 26 is formed by printing ink with a high absorption of the laser. As a specific example, the laser absorption section 26 is a black printed section, and the black printed section is printed with ink containing carbon black that improves the absorption of the laser. The laser absorption section 26 is, for example, provided on the outer surface of the biaxially stretched oriented film 21 or between the biaxially stretched oriented film 21 and the sealant film 23 before the orientation relaxation section 21a is formed. As a specific example, it is provided in the area of ​​the biaxially stretched oriented film 21 facing the adhesive layer 22 where the orientation relaxation section 21a is to be formed. In addition, in the case where the laser absorption section 26 is provided between the biaxially stretched oriented film 21 and the sealant film 23, the laser absorption section 26 is not provided at least in the area where the break section 13 is to be formed. In addition, in Fig.24, an example in which the laser light absorbing portion 26 is provided on the outer surface of the biaxially stretched oriented film 21 is shown.

[0100] Such a film 11B includes an orientation relaxation section 21a formed by heating the laser absorption section 26 to a predetermined temperature near the melting point or higher by laser in the biaxially stretched oriented film 21, and has a break section 13 between the orientation relaxation sections 21a. In addition, the orientation relaxation section 21a is configured in various shapes depending on the structure of the break section 13.

[0101] The film 11B of such a structure is first printed with ink containing carbon black or the like on the outer surface of the biaxially stretched oriented film 21 and in the region where the orientation relaxation section 21a is to be formed, and the laser absorption section 26 is formed. At this time, for example, in the case where a pair of orientation relaxation sections 21a that are long in one direction and arranged in the long side direction are formed, two rectangular laser absorption sections 26 that are long in one direction are arranged in the long side direction, and the laser absorption sections 26 are located in the region of the pair of orientation relaxation sections 21a or in a region slightly larger than the region of the pair of orientation relaxation sections 21a in the width direction.

[0102] Next, the biaxially stretched oriented film 21 and the sealant film 23 are bonded via the adhesive layer 22. Next, the laser output device 100 that outputs the laser 101 is adjusted to an output power that does not heat the biaxially stretched oriented film 21 to a predetermined temperature near the melting point or higher and that heats the laser absorption portion 26 to a predetermined temperature near the melting point or higher. Next, the laser output device 100 is controlled to scan the laser absorption portion 26.

[0103] At this time, if Fig.25 As shown by the arrow in , the laser 101 is scanned from one laser absorption part 26 through the orientation part 21b between a pair of laser absorption parts 26 to the other laser absorption part 26. Thus, in the region of the laser absorption part 26, the biaxially stretched oriented film 21 is heated to the melting point to form an orientation relaxation part 21a, and in the region where the laser absorption part 26 is not provided, the biaxially stretched oriented film 21 is not melted and still has orientation. Through these steps, the film 11B used for the package 1 can be manufactured and used for any package 1, 1A.

[0104] The film 11B having such a structure can exert the same effects as the film 11 of the first embodiment. In addition, the film 11B can be provided with the laser absorbing portion 26 in the region where the orientation relaxing portion 21a is provided. Fig.25 As shown, the process of scanning the laser beam 101 is performed once.

[0105] Specifically, when the laser is scanned to respectively provide two orientation relaxation sections 21a, two scans are required. However, by providing a laser absorption section 26 as in the film 11B and adjusting the output power of the laser 101 so as to melt the biaxially stretched oriented film 21 only in the laser absorption section 26, two orientation relaxation sections 21a can be formed by one scan. In this way, since the number of scans of the laser 101 can be reduced, the production efficiency of the film 11B can be improved, and the accuracy of the formed orientation relaxation section 21a can be improved.

[0106] In addition, in the above example, the packaging body 1 and the films 11 and 11B having the breaking portion 13 between the opposing orientation relaxation portions 21a are described, but the present invention is not limited thereto. Fig.26 As in the eleventh embodiment shown in FIG. 1 , the film 11C may be configured to have a continuous portion 21f that connects the short sides or the short side and the long side of the orientation relaxation portion 21a facing each other in the break portion 13. The continuous portion 21f is a portion that is formed as a non-oriented portion by melting the biaxially stretched oriented film 21. The continuous portion 21f constitutes a part of the break portion 13. The continuous portion 21f is provided in a part of the orientation portion 21b between the short sides or the short side and the long side of the orientation relaxation portion 21a facing each other. That is, the continuous portion 21f is configured to have a width smaller than the short side of the orientation relaxation portion 21a.

[0107] The method for manufacturing the film 11C thus constituted is, for example, first printing ink containing carbon black or the like on the outer surface of the biaxially stretched oriented film 21 and in the region where the orientation relaxing portion 21a is to be formed, and forming the laser absorbing portion 26. At this time, for example, in the case where a pair of orientation relaxing portions 21a which are long in one direction and arranged in the longitudinal direction are formed, two rectangular laser absorbing portions 26 which are long in one direction are arranged in the longitudinal direction, and the laser absorbing portions 26 are located in the region of the pair of orientation relaxing portions 21a or in a region slightly larger than the region of the pair of orientation relaxing portions 21a in the width direction.

[0108] Next, the biaxially stretched oriented film 21 and the sealant film 23 are bonded via the adhesive layer 22. Next, the laser output device 100 that outputs the laser 101 is adjusted to an output power capable of heating the biaxially stretched oriented film 21 to a predetermined temperature near the melting point or higher. Next, the laser output device 100 is controlled to scan the laser light absorbing portion 26.

[0109] At this time, the laser 101 is scanned once from one laser absorption part 26 through the orientation part 21b between a pair of laser absorption parts 26 to the other laser absorption part 26. Thus, in the region of the laser absorption part 26, the biaxially stretched oriented film 21 is heated to the melting point to form an orientation relaxation part 21a having a wider width in the short side direction, and in the region where the laser absorption part 26 is not provided, a continuous part 21f having a narrower width than the orientation relaxation part 21a is formed. Through these steps, the film 11C used for the package 1 can be manufactured and used for packages of any shape such as the packages 1 and 1A.

[0110] According to the film 11C having such a configuration, similarly to the film 11 of the first embodiment, when heated in a microwave oven, the continuous portion 21f is broken at the breaking portion 13 of the film 11 to form the steam vent 21c. This is because when heated in a microwave oven, the internal pressure in the package 1, 1A rises and the biaxially stretched oriented film 21 is stretched, and since the width of the continuous portion 21f is smaller than the width of the orientation relaxation portion 21a, the absolute value of the stretching amount of the continuous portion 21f is smaller than that of the orientation relaxation portion 21a, and therefore the continuous portion 21f is broken first.

[0111] The method for forming the orientation relaxing portion 21 a and the continuous portion 21 f is not limited to laser heating, and may be hot plate heating, pulse heating, near infrared heating, etc. The film 11C may not be provided with the laser absorbing portion 26 .

[0112] In addition, the present invention is not limited to the above-mentioned embodiment. For example, in the above-mentioned example, the packaging body is a pillow-type packaging bag of the packaging body 1, and the resin container 15 and the cover body 16 of the packaging body 1A are described, but it is not limited to this. As long as the sealed space for accommodating the content 200 is formed and the film 11, 11B, 11C is stretched according to the increase of the internal pressure of the packaging body 1, 1A and the breaking part 13 is broken, the shape of the packaging body can be appropriately set, and the film 11 can be used in the packaging body. As examples of the shape of other packaging bodies, three-way sealed flat bags, folded sealed flat bags, gusset bags, stand-up bags, etc. can be listed.

[0113] In the above example, the film 11 is described as having a higher elongation at break in the region of the orientation relaxation section 21a than in the orientation section 21b, and having a relationship between the tensile elastic modulus E1 in the molecular orientation section and the tensile elastic modulus E2 in the molecular orientation relaxation section of the film 11 being 0<E2 / E1<0.5. However, the film 11 may be configured so that either the elongation at break and the tensile elastic modulus E2 / E1 of the orientation relaxation section 21a or the orientation section 21b is set to the above relationship.

[0114] That is, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made in the implementation stage without departing from the main purpose thereof. In addition, the various embodiments can also be appropriately combined and implemented, in which case, the combined effect can be obtained. Moreover, various technical solutions are included in the above-mentioned embodiments, and various technical solutions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, in the case where deleting some constituent elements from all the constituent elements shown in the implementation can also solve the technical problem and obtain the technical effect, the structure in which the constituent elements are deleted can also be extracted as a technical solution.

[0115] Description of Reference Numerals

[0116] 1, 1A...Packaging body, 11, 11B, 11C...Film, 11a...Opening, 12...Sealing portion, 13...Breaking portion, 14...Film sheet, 15...Resin container, 15a...Flange portion, 16...Lid, 21...Biaxially stretched oriented film, 21a...Orientation relaxation portion, 21b...Orientation portion, 21c...Steam vent, 21f...Continuous portion, 22...Adhesive layer, 23...Sealant film, 24...Printing layer, 25...Protective film, 26...Laser absorbing portion, 100...Laser output device, 101...Laser, 200...Contents.

Claims

1. A film used for a packaging body, wherein the packaging body is heated by a microwave oven to increase the internal pressure of the container, and the internal steam is discharged to reduce the internal pressure, wherein: The film has: an outer film, wherein the outer film is molecularly oriented by biaxial stretching; An inner film, which is laminated on the outer film and can be heat-welded; One or more orientation relaxing sections, wherein the one or more orientation relaxing sections are formed in the outer layer film; and a rupture portion formed at a location where the one or more orientation relaxing portions face each other at a predetermined interval, and ruptured by an increase in the internal pressure of the container in the microwave oven; At least in the breaking portion, there is no printed layer between the outer layer film and the inner layer film.

2. The film according to claim 1, wherein A printed layer is provided between the outer layer film and the inner layer film in at least a part of the region excluding the break portion.

3. The film according to claim 1, wherein A printing layer is provided on the outer surface side of the outer layer film.

4. The film according to claim 3, wherein The printed layer provided on the outer surface side of the outer layer film is provided in a region excluding the break portion.

5. The film according to claim 1, wherein In the breaking portion and the orientation relaxing portion, the printed layer is not provided between the outer layer film and the inner layer film.

6. A packaging body, wherein: The packaging body uses the film according to any one of claims 1 to 5 as at least a part of the packaging material.

7. The packaging body according to claim 6, wherein: The packaging body is formed into a bag shape for accommodating contents by welding the inner layer films to each other, and the orientation relaxation portion and the breaking portion are arranged at a portion forming the bag shape.

8. The packaging body according to claim 6, wherein: The packaging body comprises: the film; and a container body having a flange disposed around the opening and accommodating the contents, The film welds the inner layer film to the flange and covers the opening, and the orientation relaxation portion and the break portion are arranged at positions facing the opening.

9. A package containing contents, wherein: The package containing the contents comprises: The packaging body according to claim 6; and Contents are arranged in the packaging body.

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