HK1210110B - Laminate film and packaging container - Google Patents

Description

Laminated film and packaging container

Technical Field

The present invention relates to a laminated film, and more particularly, to a laminated film used for a packaging container to enable the contents to be heated more appropriately by a microwave oven, and a packaging bag using the same.

The application claims priority to Japanese application laid-open application No. 2012-228075 based on 10/15/2012, the contents of which are incorporated herein by reference.

Background

Conventionally, it has been known that a food in a cooked or half-cooked state is packaged in a packaging container such as a packaging bag which can be stored at normal temperature, low temperature, or frozen state, and is heated in a microwave oven without being opened to bring the food into a consumable state.

However, when the container is heated in a microwave oven without opening the container, the moisture in the container is changed into steam, and the volume of the container is increased. Therefore, if there is no gap through which water vapor can escape, the packaging container may be broken or the like. On the other hand, when the contents are in a half-cooked state or the like, the contents may need to be cooked not only by heating but also by the generated steam. In this case, if the holes or the like for releasing steam are too large, problems such as insufficient cooking and poor taste occur.

Several types of packages corresponding to the above-mentioned uses are known. Generally, each is formed using a laminate film. When the internal pressure is increased, a crack can be generated in a part of the laminated film, and the crack can be prevented by emitting water vapor from the crack.

As a packaging bag capable of boiling the contents when heated in a microwave oven, for example, a packaging bag described in patent document 1 is known. In this packaging bag, a slit is formed through an outer layer and an inner layer in a part of a laminated film having the outer layer and the inner layer, and then the inner layer is heated and melted to seal only the slit of the inner layer. When the package is heated by a microwave oven, the inner layer is ruptured to form a small hole. Therefore, the steam can be boiled while preventing the breakage without excessively discharging the steam.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2012/086295

Disclosure of Invention

Problems to be solved by the invention

However, the packaging bag described in patent document 1 can be steamed while preventing breakage, but the processing for forming and re-welding the slit is complicated. Therefore, the manufacturing process is complicated, and it is difficult to improve the manufacturing efficiency. In addition, it is difficult to ensure the sealing quality after re-welding.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a laminated film which can prevent a crack from occurring when heating is performed in a microwave oven in the case of using the laminated film for a packaging container, and which can be easily manufactured.

Another object of the present invention is to provide a packaging container which can prevent a crack from occurring when heated by a microwave oven and which can be easily manufactured.

Means for solving the problems

The laminate film according to the first embodiment of the present invention has: an inner layer formed of a heat-weldable thermoplastic resin, an outer layer laminated on the inner layer, and a fragile processed portion in which at least a part of the outer layer is removed and at least a part of the inner layer is present, and which has a linear shape in a plan view and a Young's modulus of 2.0 gigapascals or less.

The laminate film according to the second embodiment of the present invention has: an inner layer formed of a linear low-density polyethylene resin and capable of being heat-welded, an outer layer laminated on the inner layer, a fragile processed portion, at least a part of the outer layer being removed and at least a part of the inner layer being present, the shape in a plan view being linear and having a Young's modulus of less than 2.8 gigapascals.

In addition, the composite strength of the portion in the vicinity of the fragile processed portion under a heating environment may be 0.1N/25mm or more.

Further, the fragile processed portion may be formed by laser irradiation.

The laminate film according to the first or second embodiment of the present invention may further include an intermediate layer provided between the inner layer and the outer layer.

In this case, the intermediate layer may be an ink layer that reduces the composite strength between the inner layer and the outer layer, and the intermediate layer may be formed in a region other than the fragile processed portion and the periphery of the fragile processed portion in a plan view; the intermediate layer may be a strong composite layer that improves the composite strength between the inner layer and the outer layer, and may be formed in a region including both sides of the fragile processed portion in the longitudinal direction in a plan view.

A packaging container according to a third embodiment of the present invention has the laminated film according to embodiment 1 at least partially, and a plurality of small holes are formed in the fragile processed portion when heated in a microwave oven.

ADVANTAGEOUS EFFECTS OF INVENTION

The laminated film according to the embodiment of the present invention can be used for packaging containers, and can be easily produced while preventing breakage when heated in a microwave oven.

In addition, according to the packaging container of the embodiment of the present invention, it is possible to prevent breakage when heating is performed in a microwave oven, and it is also possible to easily manufacture the packaging container.

In addition, when the laminated film or the packaging container according to the embodiment of the present invention is used, it is possible to perform retort processing satisfactorily when heating is performed in a microwave oven by applying the laminated film or the packaging container to the packaging container.

Drawings

Fig. 1 is a perspective view showing a packaging bag formed by using a laminated film according to a first embodiment of the present invention.

Fig. 2 is a sectional view taken along line a-a of fig. 1.

Fig. 3 is a schematic diagram showing a test piece when the young's modulus of the fragile processed portion is measured.

Fig. 4 is a view showing a fragile processed portion when heating using a microwave oven.

Fig. 5A is a cross-sectional view of a modification of the laminate film.

Fig. 5B is a cross-sectional view of a modification of the laminate film.

Fig. 6A is a partial plan view of a laminated film according to a second embodiment of the present invention.

Fig. 6B is a cross-sectional view taken along line B-B of fig. 6A.

Fig. 7A is a plan view showing an inner layer of a modification of the laminate film.

Fig. 7B is a plan view showing an inner layer of a modification of the laminate film.

Fig. 7C is a plan view showing an inner layer of a modification of the laminate film.

Fig. 8A is a plan view showing a fragile processed portion of the laminate film of the embodiment of the present invention.

Fig. 8B is a plan view showing a fragile processed portion of the laminate film of the embodiment of the present invention.

Fig. 8C is a plan view showing a fragile processed portion of the laminate film of the embodiment of the present invention.

Fig. 8D is a plan view showing a fragile processed portion of the laminate film of the embodiment of the present invention.

Fig. 8E is a plan view showing a fragile processed portion of the laminate film of the embodiment of the present invention.

Fig. 9 is a perspective view showing a modified example of the packaging container of the present invention.

Detailed Description

A laminated film and a packaging container according to a first embodiment of the present invention will be described with reference to fig. 1 to 5B.

Fig. 1 is a perspective view showing a packaging bag (packaging container) 1 of the present embodiment. The packaging bag 1 is formed in a bag shape using a laminate film 10 having at least one surface capable of being heat-welded.

The packaging bag 1 of the present embodiment is formed into a bag shape by thermally welding the end 10a and the end 10b of a rectangular or square piece of laminate film 10 into a substantially cylindrical shape, and then thermally welding the two ends 10c and 10d in the direction in which the tubular cavity extends, respectively, to join the two ends 10c and 10 d.

The method of forming the laminated film into a bag shape and the method of forming the laminated film into a bag shape are not particularly limited in the packaging bag of the present embodiment. For example, 2 laminated films may be arranged to face each other, and the peripheral portions may be joined by thermal welding to form a packaging bag.

Fig. 2 is a sectional view of the laminated film 10 taken along line a-a in fig. 1. The laminated film 10 is formed by laminating an outer layer 20 and an inner layer 30, wherein the outer layer 20 forms the outer surface of the packaging bag 1, and the inner layer 30 forms the inner surface of the packaging bag 1 and can be thermally welded. Both the outer layer 20 and the inner layer 30 are formed of resin.

From the viewpoint of protecting the contents, the resin forming the outer layer 20 is preferably a material having relatively high rigidity, and examples thereof include, but are not limited to, polyethylene terephthalate (PET), biaxially oriented polypropylene (OPP), and biaxially oriented nylon (ONy).

The outer layer 20 may be subjected to secondary processing such as printing or vapor deposition to improve design and display various information. Such secondary processing may be performed on either of the front and back surfaces of outer layer 20.

Since the inner layer 30 functions as a so-called sealing medium layer, a heat-weldable thermoplastic resin such as various general-purpose polyolefins and special polyolefins known in the art can be used as the resin forming the inner layer 30. Specific examples thereof include Linear Low Density Polyethylene (LLDPE), Low Density Polyethylene (LDPE), Medium Density Polyethylene (MDPE), High Density Polyethylene (HDPE), Very Low Density Polyethylene (VLDPE), unstretched polypropylene (CPP), ethylene-vinyl acetate copolymer (EVA), ethylene acrylic acid copolymer (EAA), ethylene methacrylic acid copolymer (EMAA), ethylene ethyl acrylate copolymer (EEA), ethylene methyl methacrylate copolymer (EMMA), ethylene methyl acrylate copolymer (EMA), and Ionomer (IO), but the present invention is not limited thereto.

When Linear Low Density Polyethylene (LLDPE), which is a thermoplastic resin capable of thermal fusion, is used as the resin for forming the inner layer 30, the impact-failure mass of the inner layer 30 is preferably 100g (g) or more and 800g or less, and more preferably 100g or more and 700g or less.

Further, in the embodiment of the present invention, the impact failure quality is defined as a value measured in accordance with JIS K7124 "impact test method based on plastic film and sheet-free dart method".

The outer layer 20 and the inner layer 30 are joined together by disposing an adhesive layer (not shown) between the outer layer 20 and the inner layer 30 and performing a known dry lamination process (dry lamination). The method of laminating the outer layer and the inner layer is not particularly limited, and the outer layer and the inner layer may be laminated by a method such as sandwich compounding or coextrusion with another resin described later.

As shown in fig. 1 and 2, a fragile processed portion 40 from which at least a part of the outer layer 20 is removed is provided on a part of the outer surface of the packaging bag 1. For example, in the fragile processed portion 40, a region having a width w1 of about 150 micrometers (μm) and a length l1 of 40 millimeters (mm) is removed on the outer layer 20, thereby forming the groove 40a on the region. The fragile processed portion 40 in the present embodiment is a portion which is located in the groove 40a of the laminate film 10 and is thinner than other portions, and substantially all of the outer layer 20 is removed at the fragile processed portion 40.

By removing the outer layer 20 at the fragile processed portion 40, the young's modulus (tensile modulus of elasticity) here, which indicates the slope of the stress-strain line per unit cross-sectional area, is lower than that at other portions of the laminate film 10, and thus the laminate film is likely to crack. Specifically, the young's modulus of the fragile worked portion 40 is 2.0 gigapascal (GPa) or less in measurement in conformity with JIS K7127. In addition, in particular, in the case of using Linear Low Density Polyethylene (LLDPE) as the resin forming the inner layer 30, the young's modulus of the fragile processed portion 40 may be less than 2.8 gigapascals (GPa) in the measurement conforming to jis k 7127.

Although the lower limit of the young's modulus of the fragile processed portion 40 is not particularly limited, it is not preferable that the fragile processed portion 40 is broken by an impact such as dropping when the young's modulus of the fragile processed portion 40 is smaller than the young's modulus of the inner layer single layer.

Further, since the size of the test piece is specified in JIS K7127, it is difficult to measure only the young's modulus of the fragile processed portion according to JIS K7127. Therefore, in the present invention, the young's modulus of the fragile processed portion is defined based on the young's modulus measured in conformity with JIS K7127 using the test piece Sp shown in fig. 3. In the test piece Sp, a fragile processed portion 40 extending in the direction across the entire width is formed at the center in the longitudinal direction of the laminated film 10 cut to a size prescribed in JIS K7127. Further, the cross-sectional area for calculating the young's modulus of the brittle processed product is calculated using the thickness of the brittle processed portion.

In the embodiment of the present invention, the degree of removal of the outer layer of the fragile processed portion and the processing depth are not particularly limited as long as the young's modulus satisfies the above-described conditions. For example, a thin outer layer may be left on the entire surface of the fragile processed portion without exposing the inner layer, and not only the outer layer but also a part of the inner layer may be removed. However, the fragile processing portion is formed not to penetrate the inner layer in order to prevent leakage of the contents before heating in the microwave oven. That is, in order to make the young's modulus of the fragile processed portion satisfy the above-described condition, at least a part of the outer layer may be removed and at least a part of the inner layer may be left.

The position of the fragile processed portion 40 may be any position other than the position where the end portions 10a to 10d are thermally welded to form the laminate film 10 into a bag shape, and may be formed at any position in consideration of the type of contents, the filling step, and the like.

Further, although the drawings show the case where the fragile processed portion is formed in a straight line, the fragile processed portion is not limited to this, and may be formed in a curved line shape or a zigzag line shape, for example, or in 2 or more lines as long as the above-described condition of the young's modulus is satisfied. Although the drawings show the case where the fragile processed portion is a continuous line, the fragile processed portion may be formed as a broken line or the like as long as the above-described condition of young's modulus is satisfied.

As a method of forming the fragile processed portion 40, laser processing by laser irradiation is preferable. When laser machining is used, the shape and the machining depth of the fragile machined part can be relatively easily adjusted by adjusting the output and the scanning speed of the laser head. However, the forming method is not limited to laser processing, and other methods can be used.

The laminated film 10 having the fragile processed portion 40 formed at an arbitrary position is formed into a substantially bag shape with an open end left, and the open end is filled with contents from the open end and then heat-welded, thereby completing the packaging bag 1 filled with contents. When the packaging bag 1 of the present embodiment filled with the content is placed in a microwave oven and heated, moisture contained in the content turns into steam and expands, and the internal pressure of the packaging bag 1 rises.

However, the inventors of the present invention have found that when the young's modulus of the fragile processed portion 40 defined above is set to be less than the predetermined value, the fragile processed portion 40 does not entirely crack but a plurality of small holes 41 separated from each other are formed as shown in fig. 4 when the internal pressure of the packaging bag 1 is increased by heating in a microwave oven, when the fragile processed portion 40 is set to have a young's modulus less than the predetermined value.

Basically, the fragile worked portion 40 is easily deformed in the longitudinal direction thereof, but is hardly deformed near the portion joined to the outer layer 20 in the direction perpendicular to the longitudinal direction. Therefore, it is considered that in the fragile worked portion 40, the stress concentrates on several points separated from each other. The reason why the crack does not expand so as to connect the small hole 41 formed is that the internal pressure is reduced by the release of the water vapor from the small hole 41.

The inventors have also found that when the fragile processed portion 40 is formed by laser processing, a plurality of small holes 41 are formed at relatively short equal intervals in the longitudinal direction of the fragile processed portion 40. It is presumed that this is because the output of the laser light varies periodically, and therefore, a deep portion and a shallow portion are repeatedly formed in the groove formed when the fragile processing portion is formed, and the deep portion of the groove, that is, the thin portion in the fragile processing portion is rapidly cracked to form the small hole.

In addition, in the case where the inner layer 30 is formed of LLDPE, since LLDPE has high flexibility and is easily stretched and also has high impact strength, it is possible to withstand the internal pressure acting on the laminated film even after the small holes 41 are formed, thereby preventing communication between the small holes and breakage.

Since the fragile processed portion 40 has the plurality of small holes 41 formed therein, the water vapor generated inside the packaging bag 1 is not released to the outside of the packaging bag 1 at a time, but is released continuously to such an extent that the breakage is prevented as needed along with the increase in the internal pressure. Thus, even when heated in a microwave oven, the packaging bag 1 can be properly cooked with the steam remaining therein without causing cracks or the like.

As described above, according to the packaging bag 1 including the laminated film 10 of the present embodiment, since the fragile processed portion 40 is formed with the plurality of small holes 41 when heated by the microwave oven, it is possible to suitably prevent the breakage or the like caused by the increase of the internal pressure, and it is possible to suitably perform the boiling while retaining a part of the water vapor in the packaging bag.

In addition, when the fragile processed portion 40 is provided, it is not necessary to perform a step of cutting the inner layer in the slit and then welding the inner layer. Therefore, the manufacturing process of the laminate film 10 can be simplified. Therefore, the packaging bag 1 can be easily manufactured.

Further, the fragile processed portion 40 can be formed at any portion of the laminate film except for the end portion where the inner layer 30 is heat-welded, and the degree of freedom in designing the packaging bag is high. Therefore, even when a plurality of types of packaging bags having different positions of formation of the fragile processed portion are manufactured according to the types of contents, for example, the packaging bags can be easily manufactured by changing the irradiation position of the laser beam, for example.

In the present embodiment, the outer layer and the inner layer are not necessarily a single layer. In the laminate film 10A of the modification shown in fig. 5A, the outer layer 20A has a first layer 21 formed of a first resin and a second layer 22 formed of a second resin different from the first resin.

In the laminate film 10B of the modification shown in fig. 5B, the inner layer 30A joined to the outer layer 20A has an upper layer 31 formed of a third resin and a lower layer 32 formed of a fourth resin different from the third resin. Preferably, for example, when LLDPE is used as the inner layer 30A, the inner layer 30A has an upper layer 31 formed of LLDPE and a lower layer 32 formed of LLDPE having different physical properties from the upper layer 31. In the structure shown in fig. 5B, the outer layer 20A and the lower layer 32 are bonded to each other with a third resin by a sandwich lamination method, whereby the laminate film 10B can be formed without using an adhesive layer.

The number of layers and the structure are not limited as long as the fragile processed portion can be formed, and for example, the inner layer may be 2 layers and the outer layer may be 1 layer, or each may have 3 or more layers.

In addition, in the embodiment of the present invention, it is preferable that the composite strength of the portion in the vicinity of the fragile processed portion under the heating environment is 0.1N/25mm or more. In the case where the composite strength in a heated environment is 0.1N/25mm or more, in the case where the inner volume of the packaging material expands when heated in a microwave oven, by bonding the outer layer and the inner layer in the region other than the fragile processed portion, stress due to the volume expansion is applied to the inner layer of the fragile processed portion in a limited manner, thereby effectively stretching the inner layer of the region to cause local breakage, and therefore, it is possible to restrict the occurrence of the vapor vent hole in the fragile processed portion.

On the other hand, in the case where the composite strength in a heating environment is less than 0.1N/25mm, in the case where the inner volume of the packaging material expands upon heating in a microwave oven, the outer layer and the inner layer are peeled off due to the stress to be stretched by the inner layer. Thus, the inner layer becomes a single layer and stretches infinitely. When the internal volume is excessively expanded, an unspecified place may be burst due to a decrease in strength of the inner layer.

A laminated film and a packaging bag according to a second embodiment of the present invention will be described with reference to fig. 6A to 7C. The laminated film 51 of the present embodiment is different from the laminated film 10 forming the packaging bag 1 of the first embodiment in that an intermediate layer is provided between the outer layer and the inner layer. In the following description, the same components as those already described are denoted by the same reference numerals, and redundant description thereof is omitted.

In addition, in the present embodiment, the young's modulus of the fragile processed portion 40 is also 2.0 gigapascal (GPa) or less in measurement in compliance with JIS K7127. In the present embodiment, particularly in the case where Linear Low Density Polyethylene (LLDPE) is used as the resin forming the inner layer 30, the young's modulus of the fragile processed portion 40 may be less than 2.8 gigapascals (GPa) in a measurement in compliance with JIS K7127. In the embodiment of the present invention, the composite strength of the portion in the vicinity of the fragile processing portion in the heated environment is preferably 0.1N/25mm or more.

Fig. 6A is a partial plan view of the laminate film 51 of the present embodiment, and fig. 6B is a cross-sectional view taken along the line B-B in fig. 6A. As shown in fig. 6B, an ink layer (intermediate layer) 52 is formed between the outer layer 20 and the inner layer 30 of the laminate film 51.

The ink layer 52 is provided to improve the design of the packaging container and to have functions such as various displays related to products, and can be formed using various known inks.

In general, after the ink layer 52 is inserted, the composite strength of the outer layer 20 and the inner layer 30 is reduced, and when the composite strength of the fragile processed portion 40 and the periphery thereof is reduced, pinholes may not be formed well upon heating. In order to prevent this, in the present embodiment, as shown in fig. 6A, ink layer 52 is not formed on the fragile processed portion and the periphery thereof. The range in which the ink layer 52 is not formed may be appropriately set around the fragile processed portion 40, and for example, a rectangular range including positions shifted by 5mm to both sides in the longitudinal direction and 2.5mm to both sides in the width direction with the fragile processed portion 40 as the center may be set.

In the case where the composite strength between the outer layer and the inner layer is not high, the composite strength can be improved by providing the intermediate layer, depending on the compatibility of the material and the like. Fig. 7A to 7C show a modification for improving the composite strength between the outer layer and the inner layer.

Fig. 7A to 7C are partial plan views showing the laminated film in all modifications except for the outer layer. A strong composite layer 56 is formed by applying a reinforcing material (medium) to the surface of the inner layer 55 to be joined to the outer layer. In addition, in the portion where the strong composite layer 56 is formed, the composite strength of the outer layer and the inner layer is improved relative to other portions. As shown in fig. 7A, when the strong composite layers 56 are formed on both sides in the longitudinal direction of the weak processed portion 40 (the weak processed portion is formed only on the outer layer, and is shown by a broken line), the stress applied to the weak processed portion 40 is not uniform due to the presence of the strong composite layers 56, and the small hole 41 is formed at the portion P where the extension line of the weak processed portion 40 intersects with the strong composite layers 56.

Therefore, the strong composite layer (intermediate layer) 56 in this modification may be formed at least on both longitudinal sides of the fragile processed portion 40, and may be formed entirely around the fragile processed portion 40 as shown in fig. 7B, or may be formed so as to cover all of both longitudinal sides of the fragile processed portion as shown in fig. 7C, as long as this condition is satisfied. Although not shown, the strong composite layer may be formed on the entire surface of the laminate film.

In the laminated film 51 of the present embodiment, similarly to the laminated film 10 of the first embodiment, when used for a packaging container, when heated in a microwave oven, it is possible to appropriately prevent cracking or the like due to an increase in internal pressure, and to appropriately perform retort processing.

Further, since the intermediate layer is provided between the outer layer and the inner layer, by appropriately adjusting the composite strength of the fragile processed portion and the periphery thereof, even if a larger number of materials are used for the outer layer and the inner layer, it is possible to appropriately form pores at the fragile processed portion upon heating.

Further, if the intermediate layer is used as the ink layer, it is possible to easily impart design properties to the packaging bag formed of the laminated film, display product information, and the like.

Next, the present invention will be further described using examples.

Example 1 group

Example 1 group: the outer layer and the inner layer are each composed of a single layer.

(example 1-1)

A PET film having a thickness of 12 μm was used as the outer layer, and a LLDPE film having a thickness of 30 μm (Young's modulus of 0.15 GPa; measured in accordance with JIS K7127, the same shall apply hereinafter) was used as the inner layer. The outer layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based dry lamination adhesive, and a fragile processed portion having a width of 150 μm, a length of 40mm and a depth substantially penetrating the outer layer was formed by laser irradiation, thereby producing the laminate film of example 1-1.

On the laminate film of example 1-1, the Young's modulus of the fragile processed portion measured by the above-mentioned method was 1.6GPa, and the composite strength of the outer layer and the inner layer (measured in accordance with JIS K6854) was 8N/25 mm.

The laminated film was formed into a bag shape by the above-described method, and a packaging bag of the present example was manufactured. Since the packaging bag is formed in a substantially rectangular parallelepiped shape, a surface including a joint portion between the end portion 10a and the end portion 10b is a lower surface, a surface opposite thereto is an upper surface, and a surface between the lower surface and the upper surface is a side surface. The packaging bag of example 1-1 was formed such that the fragile processed portion was located on the upper surface.

(examples 1 to 2)

The same laminate film as in example 1-1 was used as a laminate film. The packaging bag of example 1-2 was formed such that the fragile processed portion was located on the side surface.

(examples 1 to 3)

The same laminate film as in example 1-1 was used as a laminate film. The packaging bag of example 1-2 was formed such that the fragile processed portion was located on the lower surface.

(examples 1 to 4)

The materials of the outer layer and the inner layer were the same as those of example 1-1. The fragile processing portion is formed in a dotted line shape by laser irradiation. The dotted line is formed by repeating 30 grooves having a length of 1mm at intervals of 0.1 mm. The Young's modulus of the fragile worked portion was 1.6 GPa.

The packaging bags of examples 1 to 4 were formed such that the fragile processing portion was located on the upper surface.

(examples 1 to 5)

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that a LLDPE film (Young's modulus of 0.15GPa) having a thickness of 40 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 1.7GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

(examples 1 to 6)

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that an LLDPE film (Young's modulus of 0.12GPa) having a thickness of 30 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

(examples 1 to 7)

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that an LLDPE film (Young's modulus of 0.05GPa) having a thickness of 30 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 1.0GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

(examples 1 to 8)

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that an EVA film (Young's modulus 0.16GPa) having a thickness of 30 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 1.7GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

(examples 1 to 9)

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that an LDPE film (Young's modulus of 0.3GPa) having a thickness of 30 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 2.0GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

Comparative example 1-A

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that a CPP film (Young's modulus of 0.7GPa) having a thickness of 30 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 2.2GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

Comparative example 1-B

A laminated film and a packaging bag were produced in the same manner as in example 1-1, except that a CPP film (Young's modulus of 0.8GPa) having a thickness of 30 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 2.5GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

The heating test using a microwave oven was performed on the packaging bags of the above examples and comparative examples in the following manner.

When forming a packaging bag, a cloth frozen in a state of containing 50cc of water is placed as a content in the packaging bag, and then the end of the packaging bag is closed and sealed. The packaging bag containing the contents was heated for 2 minutes in a microwave oven with an output of 600 watts, and the presence or absence of cracking and the state of cooking were observed. Rupture is defined as a state in which one of the following conditions occurs: the packaging bag may be cracked at a portion other than the fragile processed portion, or the crack may extend to a portion other than the fragile processed portion although the fragile processed portion is cracked. In the case of cooking, in heating, a case where vapor holes in units of mm or less than or equal to 1mm are formed in the fragile processed portion and the expanded state is well maintained is evaluated as "good"; a product in which vapor pores are formed in cm in the fragile worked portion and the expanded state is maintained to some extent is rated as "medium"; the product was rated "poor" in that the brittle processed portion was not cracked, or the brittle processed portion was cracked but the crack extended to a portion other than the brittle processed portion and the expansion state could not be maintained. The results of examples 1-1 to 1-8 and comparative examples 1-A to 1-C are shown in Table 1.

[ Table 1]

As shown in Table 1, in examples 1-1 to 1-8 in which the Young's modulus of the fragile processed portion was 2.0GPa or less, a large number of small holes were formed in the fragile processed portion during heating, and steam was released to the outside of the packaging bag without causing cracking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag. In addition, in examples 1 to 9, since a large crack was formed in the entire fragile processed portion, the breakage was prevented.

In contrast, in comparative examples 1-A and 1-B, cracks occurred in the fragile processed portion and the end portion of the laminated film after heat-sealing, respectively.

(example 2 group)

Example 2 group is an example in which at least one of the outer layer and the inner layer is composed of a plurality of layers.

(example 2-1)

A PET film having a thickness of 12 μm and an ONy film having a thickness of 15 μm were used as the outer layers, and an LLDPE film having a thickness of 40 μm (Young's modulus of 0.15GPa) was used as the inner layer.

The laminated film of example 2-1 was produced by bonding the PET film and the ONy film and the outer layer and the inner layer by a dry lamination process using a fatty acid ester-based dry lamination adhesive, and forming a fragile processed portion having a width of 150 μm, a length of 40mm, and a depth substantially penetrating the outer layer by laser irradiation. In the laminate film of example 2-1, the Young's modulus of the fragile processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

The packaging bag of this example was produced by forming the laminate film of example 2-1 into a bag-like shape in the same manner as in example 1-1.

(example 2-2)

The structure of the outer layer was the same as that of example 2-1, and an LLDPE film having a thickness of 40 μm was prepared as the inner layer.

After the films of the outer layer were joined together by dry lamination, the outer layer and the inner layer were joined together by sandwich lamination using LDPE as the intermediate layer. Thus, a laminate film of example 2-2 (Young's modulus of the inner layer was 0.15GPa) was produced, which had a two-layer structure of LDPE (thickness: 13 μm) and LLDPE as the inner layer. In the laminate film of example 2-2, the Young's modulus of the fragile processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

The packaging bag of this example was produced by forming the laminate film of example 2-1 into a bag-like shape in the same manner as in example 1-1.

Comparative example 2-A

A laminated film of comparative example 2-A was produced in the same manner as in example 2-1, except that the depth of the fragile processed part was set to a depth that penetrates only approximately the PET film. In the laminate film of comparative example 2-A, the Young's modulus of the fragile processed portion was 3.5GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

The packaging bag of this comparative example was produced by forming the laminate film of comparative example 2-A into a bag shape in the same manner as in example 1-1.

Comparative example 2-B

A laminated film of comparative example 2-B was produced in the same manner as in example 2-1, except that the depth of the brittle processed portion was changed to a depth reaching the middle portion of the ONy film in the thickness direction. In the laminate film of comparative example 2-B, the Young's modulus of the fragile processed portion was 3.1GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

The packaging bag of this comparative example was produced by forming the laminate film of comparative example 2-B into a bag-like shape in the same manner as in example 1-1.

Table 2 shows the results of the heating test performed on the packaging bags of examples 2-1 to 2-2 and comparative examples 2-A and 2-B in a microwave oven under the same conditions as those of the group of example 1.

[ Table 2]

As shown in table 2, in examples 2-1 and 2-2 in which the young's modulus of the fragile processed portion was 2.0GPa or less, a plurality of small holes were formed in the fragile processed portion during heating, and steam was released to the outside of the packaging bag without causing cracking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

In contrast, in any of the comparative examples, the end portions of the heat-welded laminate film were cracked.

Example 3 group

Example 3 group is examples having an ink layer as an intermediate layer that reduces the composite strength.

(example 3-1)

A PET film having a thickness of 12 μm was used as the outer layer, and an LLDPE film having a thickness of 30 μm (Young's modulus of 0.15GPa) was used as the inner layer. An ink layer was formed on one surface of the PET film by printing using a white ink, except for a rectangular area of 50mm × 5 mm. Then, the surface of the outer layer on which the ink layer is provided and the inner layer are joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination. Then, a fragile processed portion having a width of 150 μm and a length of 40mm and a depth substantially penetrating the outer layer was formed by laser irradiation, and the fragile processed portion was located in a region where the ink layer was not formed in a plan view, thereby producing the laminate film of example 3-1. In the laminate film of example 3-1, the Young's modulus of the fragile processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

The packaging bag of this example was produced by forming the laminate film of example 3-1 into a bag-like shape in the same manner as in example 1-1.

(example 3-2)

A laminated film and a packaging bag were produced in the same manner as in example 3-1, except that a LLDPE film (Young's modulus of 0.15GPa) having a thickness of 40 μm was used as the inner layer. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

(examples 3 to 3)

A laminated film and a packaging bag were produced in the same manner as in example 3-1, except that the shape of the fragile processed portion was changed to the same shape as in example 1-4. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 8N/25 mm.

(examples 3 to 4)

A laminated film and a packaging bag were produced in the same manner as in example 3-1, except that the ink layer was formed on the entire surface of the PET film. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 1.8N/25 mm.

Table 3 shows the results of the heating test performed on the packaging bags of examples 3-1 to 3-4 in a microwave oven under the same conditions as those of the group of example 1.

[ Table 3]

As shown in Table 3, in examples 3-1 to 3-3 in which the Young's modulus of the fragile processed portion was 2.0GPa or less and the ink layer was not formed around the fragile processed portion, a large number of small holes were formed in the fragile processed portion during heating, and steam was released to the outside of the packaging bag without breaking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

On the other hand, in examples 3 to 4, the steam cooking was performed while preventing the breakage, but the number of small holes formed in the fragile processed portion was smaller than that in the other examples, and the steam was ejected from the packaging bag. Therefore, it is shown that the ink layer is preferably provided so as to avoid the periphery of the fragile processed portion.

Example 4 group

Example 4 group is examples in which a strong composite layer for increasing the composite strength is used as an intermediate layer.

(example 4-1)

A PET film having a thickness of 12 μm was used as the outer layer, and an LLDPE film having a thickness of 40 μm (Young's modulus of 0.16GPa) was used as the inner layer. On one surface of the outer layer, a reinforcing material coating layer (reinforcing composite layer) of 10mm × 5mm was formed by printing on both sides in the longitudinal direction of the region where the fragile processed portion was formed. The surface of the outer layer provided with the reinforcing material coating layer and the inner layer are joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination. Further, a fragile processed portion having a width of 150 μm and a length of 40mm and a depth substantially penetrating the outer layer was formed by laser irradiation so that the fragile processed portion was positioned between 2 reinforcing material coating layers in a plan view, thereby producing the laminate film of example 4-1. In the laminate film of example 4-1, the Young's modulus of the fragile processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer in the reinforcing material coating layer was 5N/25 mm.

The packaging bag of this example was produced by forming the laminate film of example 4-1 into a bag-like shape in the same manner as in example 1-1.

(example 4-2)

A laminated film and a packaging bag were produced in the same manner as in example 4-1, except that the reinforcing material coating layer was formed on the entire surface of the PET film (outer layer) except for the 50mm × 5mm unformed region, and the fragile processed portion located in the unformed region in a plan view was formed. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer in the reinforcing material coating was 5N/25 mm.

(examples 4 to 3)

A laminated film and a packaging bag were produced in the same manner as in example 4-1, except that the reinforcing material coating layer was formed on the entire surface of the PET film except for the non-formed region formed with a width of 50mm from one end to the other end in the width direction of the PET film, and the fragile processed portion located in the non-formed region in plan view was formed. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer in the reinforcing material coating was 5N/25 mm.

(examples 4 to 4)

A laminated film and a packaging bag were produced in the same manner as in example 4-1, except that the shape of the fragile processed portion was changed to the same shape as in example 1-4. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer in the reinforcing material coating was 5N/25 mm.

(examples 4 to 5)

A laminated film and a packaging bag were produced in the same manner as in example 4-1, except that the reinforcing material coating layer was not provided. The Young's modulus of the brittle processed portion was 1.6GPa, and the composite strength of the outer layer and the inner layer was 2N/25 mm.

Table 4 shows the results of the heating test performed on the packaging bags of examples 4-1 to 4-5 in a microwave oven under the same conditions as those of the group of example 1.

[ Table 4]

As shown in Table 4, in examples 4-1 to 4-4 in which the Young's modulus of the brittle processed portion was 2.0GPa or less and the reinforcing material coating layers were provided on both sides in the longitudinal direction of the brittle processed portion, small holes were formed at the intersections (2 places) between the reinforcing material coating layer and the extension line of the brittle processed portion during heating, and steam was released to the outside of the packaging bag without causing cracking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

In addition, in examples 4 to 5 in which the reinforcing material coating layer was not provided, a large crack could be formed in the entire brittle processed portion to prevent cracking.

Example 5 group

The outer and inner layers of the example 5 group were each composed of a single layer.

In examples 5-1 to 5-3, a PET film having a thickness of 12 μm was used as the outer layer, and LLDPE having a thickness of 30 μm or 40 μm was used as the inner layer. The outer layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based dry lamination adhesive, and a fragile processed portion having a width of 150 μm, a length of 40mm and a depth substantially penetrating the outer layer was formed by laser irradiation to manufacture a laminate film.

In examples 5-4 to 5-6, PET having a thickness of 16 μm was used as the outer layer, and LLDPE having a thickness of 30 μm or 40 μm was used as the inner layer. Then, bonding was performed by the same method. Further, the Young's modulus of the brittle processed parts of examples 5-1 to 5-6 was in the range of 1.8 to 2.0GPa, respectively.

Examples 5-7 used a 12 μm thick PET film as the outer layer and a Low Density Polyethylene (LDPE) (40 μm thick) as the inner layer. Further, the Young's modulus of the brittle processed portions of examples 5 to 7 was 2.0 GPa.

In comparative examples 5-A to 5-B, a PET film having a thickness of 12 μm was used as the outer layer, and unstretched polypropylene (CPP) (having a thickness of 40 μm) was used as the inner layer. The Young's modulus of the brittle processed portion of comparative example 5-A was 2.2GPa, and that of the brittle processed portion of comparative example 5-B was 2.5 GPa.

The films of examples and comparative examples were formed into a bag shape to form a packaging bag.

The packaging bags of the examples and comparative examples were subjected to a heating test in a microwave oven in accordance with the following method.

In forming the packaging bag, a cloth frozen in a state of containing 50cc of water is placed as a content in the packaging bag, and then the end of the packaging bag is closed and sealed. The packaging bag containing the contents was heated for 2 minutes in a microwave oven at an output of 600 watts, and the presence or absence of rupture and the state of cooking were observed. Table 5 shows the results of examples 5-1 to 5-7 and comparative examples 5-A to 5-B.

[ Table 5]

As shown in table 5, in the packaging bags of the examples, the inner layers in examples 5-1 to 5-6 using LLDPE as the inner layer were easily stretched, and a large number of small holes were formed in the fragile processed portion formed by laser irradiation, so that steam could be released to the outside of the packaging bag without causing cracking. In addition, the expansion state of the packaging bag can be maintained, and the steaming can be properly carried out. In addition, in example 7 using LDPE having a young's modulus of 2.0GP in the fragile worked portion, the fragile worked portion was integrally formed with a large opening so as to prevent cracking.

In contrast, in the comparative example, since the resin forming the inner layer was not LLDPE and the elongation was low, cracks occurred in the extension line of the fragile processed portion or the end portion of the heat-welded laminate film.

Example 6 group

Example 6 group is an example in which at least one of the outer layer and the inner layer is composed of a plurality of layers.

(example 6-1)

A PET film having a thickness of 12 μm and an ONy film having a thickness of 15 μm were used as the outer layers, and an LLDPE film having a thickness of 40 μm was used as the inner layer. The laminate film of example 6-1 was produced by bonding the PET film and the ON film and the outer layer and the inner layer by a dry lamination process using a fatty acid ester-based dry lamination adhesive, and then forming a fragile processed portion having a width of 150 μm, a length of 40mm, and a depth of substantially penetrating the outer layer by laser irradiation.

The packaging bag of this example was produced by forming the laminate film of example 6-1 into a bag-like shape in the same manner as in example 5-1.

(example 6-2)

So that the structures of the outer layer and the inner layer were the same as those of example 6-1.

After the films of the outer layer were joined by a dry lamination process, the outer layer and the inner layer were joined by sandwich lamination using LDPE as an intermediate layer. In this way, the laminate film of example 6-2 in which the outer layer and the inner layer were joined by the adhesive layer (thickness 13 μm) made of LDPE was produced. The packaging bag of the present example was produced by forming the laminate film of example 6-2 into a bag shape in the same manner as in example 5-1.

The Young's modulus of the brittle processed portions of examples 6-1 and 6-2 was 1.6 GPa.

Table 6 shows the results of the heating test performed on the packaging bags of examples 6-1 and 6-2 in a microwave oven under the same conditions as those of the group of example 5.

[ Table 6]

As shown in Table 6, in examples 6-1 and 6-2, a plurality of small holes were formed in the fragile processed portion during heating, and steam was released to the outside of the packaging bag without causing breakage. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

Example 7 group

Example 7 is an example in which an ink layer for reducing the composite strength is used as an intermediate layer.

(example 7-1)

A PET film having a thickness of 12 μm was used as the outer layer, and an LLDPE film having a thickness of 40 μm was used as the inner layer. An ink layer was formed on one surface of the PET film by printing using a white ink, and the ink layer was not formed on a substantially strip-shaped region having a width of 2.5mm extending in four directions of the linear fragile processed portion (the size and the forming method were the same as those of example 5-1). The surface of the outer layer provided with the ink layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination, and a fragile processed portion was formed by laser irradiation, thereby producing a laminate film of example 7-1.

The packaging bag of this example was produced by forming the laminate film of example 7-1 into a bag-like shape in the same manner as in example 5-1.

(example 7-2)

Example 7-2 was different from example 7-1 in the shape in plan view of the fragile processed portion, in that an LLDPE film having a thickness of 30 μm was used. The fragile processing portion is formed into a dotted line shape by laser irradiation. The dotted line has a shape in which a plurality of grooves having a length of 1mm are repeatedly formed at intervals of 0.1 mm.

(examples 7-3 to 7-7)

Examples 7-3 to 7-7 differ from example 7-1 only in the shape of the fragile machined portion in a plan view. FIGS. 8A to 8E show the shapes of the brittle processed parts in plan views in examples 7-3 to 7-7, respectively.

(examples 7 to 8)

A laminated film and a packaging bag of example 7-8 were produced in the same manner as in example 7-1, except that an ink layer was formed on the entire surface of one side of the PET film (i.e., no area where no ink layer was formed).

Further, the Young's modulus of the brittle processed portion in examples 7-1 to 7-8 was 1.6 GPa.

Table 7 shows the results of the heating test conducted on the packaging bags of examples 7-1 to 7-8 in a microwave oven under the same conditions as those of the group of example 5.

[ Table 7]

As shown in Table 7, in examples 7-1 to 7-3 in which no ink layer was formed around the fragile processed portion, a plurality of small holes were formed in the fragile processed portion during heating, and steam was released to the outside of the packaging bag without breaking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag. In examples 7-2 to 7-7, the fragile processing portion was formed in a special shape other than a simple straight line, and thus, the fragile processing portion was easily distinguished from a flaw or a pinhole which was unintentionally formed in the manufacturing process of the packaging bag. In example 7-6, the test piece was formed in the shape indicated by the broken line in fig. 8D, but it is considered that the same result can be obtained by disposing the intersection of the fragile processed portion near the center of the test piece.

On the other hand, although examples 7 to 8 were able to perform steaming while preventing breakage, the number of small holes formed in the fragile processed portion was smaller than that of the other examples, and steam was ejected from the packaging bag. Therefore, it is shown that the ink layer is preferably provided so as to avoid the periphery of the fragile processed portion.

Example 8 group

The example 8 group is examples having a strong composite layer for increasing the composite strength as an intermediate layer.

(example 8-1)

An outer layer of a PET film having a thickness of 12 μm was used as the outer layer, and an LLDPE film having a thickness of 40 μm was used as the inner layer. On one surface of the outer layer, a reinforcing material coating layer (reinforcing composite layer) of 10mm × 5mm was formed by printing on both sides in the longitudinal direction of the region where the fragile processed portion was formed. The surface of the outer layer provided with the reinforcing material coating layer and the inner layer are joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination. Further, a fragile processed portion having a width of 150 μm and a length of 40mm and a depth substantially penetrating the outer layer was formed by laser irradiation, and the fragile processed portion was positioned between 2 reinforcing material coating layers in a plan view, thereby producing the laminate film of example 8-1. In the laminate film of example 8-1, the composite strength of the outer layer and the inner layer in the coating layer of the reinforcing material was 5N/25 mm.

The packaging bag of this example was produced by forming the laminate film of example 8-1 into a bag-like shape in the same manner as in example 5-1.

(example 8-2)

A laminated film and a packaging bag were produced in the same manner as in example 8-1, except that the reinforcing material coating layer was formed on the entire surface of the PET film except for the 50mm × 5mm non-formed region, and the fragile processed portion located in the non-formed region in the plan view was formed. The composite strength of the outer layer and the inner layer in the reinforcing material coating is 5N/25 mm.

(examples 8 to 3)

A laminated film and a packaging bag were produced in the same manner as in example 8-1, except that the reinforcing material coating layer was formed on the entire surface of the PET film except for the non-formed region formed with a width of 50mm from one end to the other end in the width direction of the PET film, and the fragile processed portion located in the non-formed region in plan view was formed. The composite strength of the outer layer and the inner layer in the reinforcing material coating is 5N/25 mm.

(examples 8 to 4)

A laminated film and a packaging bag were produced in the same manner as in example 8-1, except that the shape of the fragile processed portion was changed to the same shape as in example 7-2. The composite strength of the outer layer and the inner layer in the reinforcing material coating is 5N/25 mm.

Further, the Young's modulus of the brittle processed portion in examples 8-1 to 8-4 was 1.6 GPa.

Table 8 shows the results of the heating test conducted on the packaging bags of examples 8-1 to 8-4 in a microwave oven under the same conditions as those of the group of example 5.

[ Table 8]

As shown in Table 8, in examples 8-1 to 8-4 in which the reinforcing material coating layer was provided on both sides in the longitudinal direction of the fragile processed portion, small holes were formed at the intersections (2 places) between the extension line of the fragile processed portion and the reinforcing material coating layer at the time of heating, and steam was released to the outside of the packaging bag without causing cracking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

Example 9 group

Example 9 group is examples having an ink layer for decreasing the composite strength as an intermediate layer.

(example 9-1)

A PET film having a thickness of 12 μm was used as the outer layer, and an LLDPE film having a thickness of 40 μm (Young's modulus of 0.15GPa) was used as the inner layer. By printing with ink, an ink layer was formed on one surface of the PET film except for the rectangular area of 50mm × 5 mm. Then, the surface of the outer layer on which the ink layer is provided and the inner layer are joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination. Then, a fragile processed portion having a width of 150 μm and a length of 40mm and a depth penetrating substantially through the outer layer was formed by laser irradiation, and the fragile processed portion was located in a region where the ink layer was not formed in a plan view, thereby producing the laminate film of example 9-1. In the laminate film of example 9-1, the Young's modulus of the fragile processed portion was 1.6 GPa.

The packaging bag of this example was produced by forming the laminate film of example 9-1 into a bag-like shape in the same manner as in example 1-1.

(example 9-2)

A laminated film and a packaging bag were produced in the same manner as in example 9-1, except that an LLDPE film having a Young's modulus of 0.27GPa was used as the inner layer. The Young's modulus of the fragile worked portion was 1.8 GPa.

(examples 9 to 3)

A laminated film and a packaging bag were produced in the same manner as in example 9-1, except that a PET film having a thickness of 16 μm was used as the outer layer. The Young's modulus of the fragile worked portion was 2.0 GPa.

(examples 9 to 4)

A laminated film and a packaging bag were produced in the same manner as in example 9-1, except that a PET film having a thickness of 25 μm was used as the outer layer. The Young's modulus of the fragile worked portion was 2.6 GPa.

(examples 9 to 5)

In examples 9 to 5, a laminated film and a packaging bag were produced in the same manner as in example 9 to 1, except that an LLDPE film having a thickness of 30 μm was used as the inner layer, and that a primer (AC: anchor coat) agent made of LDPE was applied to the printed surface of the outer layer, and the outer layer and the inner layer were joined by extrusion lamination. The LDPE formed between the outer layer and the inner layer had a thickness of 20 μm, and the brittle processed portion had a Young's modulus of 1.6 GPa.

Comparative example 9-A

A laminated film and a packaging bag were produced in the same manner as in example 9-1, except that a PET film having a thickness of 25 μm was used as the outer layer and a LLDPE film having a Young's modulus of 0.45GPa was used as the inner layer. The Young's modulus of the fragile worked portion was 2.8 GPa.

Table 9 shows the results of the heating test performed on the packaging bags of examples 9-1 to 9-5 and comparative example 9-A in a microwave oven under the same conditions as those of the example 5 group.

[ Table 9]

As shown in Table 9, in examples 9-1 to 9-5 in which the Young's modulus of the brittle processed portion of the LLDPE film was less than 2.8, a large number of small holes were formed in the brittle processed portion upon heating, and steam was released to the outside of the packaging bag without causing cracking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

In contrast, in comparative example 9-A, the Young's modulus of the fragile processed portion was 2.8 or more, and the seal portion was broken.

Example 10 group

Example 10 group is examples relating to laminated films having various layer structures.

(example 10-1)

A PET film having a thickness of 12 μm was used as the outer layer, and an LLDPE film having a thickness of 40 μm (Young's modulus of 0.15GPa) was used as the inner layer. The outer layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based dry lamination adhesive, and a fragile processed portion having a width of 150 μm, a length of 40mm and a depth substantially penetrating the outer layer was formed by laser irradiation to manufacture a laminate film of example 10-1.

In the laminated film of example 10-1, the Young's modulus of the fragile processed portion measured by the above method was 1.6 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 3N/25 mm.

(example 10-2) a laminate film and a packaging bag were produced in the same manner as in example 10-1, except that an ink layer other than a rectangular area of 50mm × 5mm was formed on one surface of a PET film by printing using ink, and then the surface provided with the ink layer of the outer layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination.

In the laminate film of example 10-2, the Young's modulus of the fragile processed portion was 1.6 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 1.2N/25 mm.

(examples 10 to 3)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that an undercoating (AC) agent made of LDPE was applied to the printing surface of the outer layer, and the outer layer and the inner layer were joined by extrusion lamination.

In the laminated film of example 10-3, the Young's modulus of the fragile processed portion was 1.6 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 2N/25 mm.

(examples 10 to 4)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that a LLDPE film having a thickness of 30 μm was used as the inner layer, that a Heat Seal (HS) varnish was formed on the entire surface of one surface of the PET film by printing using the Heat Seal (HS) varnish, and that the surface provided with the ink layer in the outer layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination.

In the laminated film of example 10-4, the Young's modulus of the fragile processed portion was 1.6 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 0.05N/25 mm.

(examples 10 to 5)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that an LDPE film (Young's modulus of 0.3GPa) having a thickness of 40 μm was used as the inner layer.

In the laminated films of examples 10 to 5, the Young's modulus of the fragile processed portion was 2.0 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 3N/25 mm.

Comparative example 10-A

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that a CPP film (Young's modulus of 0.7GPa) having a thickness of 40 μm was used as the inner layer.

In the laminate film of comparative example 10-A, the Young's modulus of the fragile processed portion was 2.5 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 3N/25 mm.

(examples 10 to 6)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that a PET film having a thickness of 16 μm was used as the outer layer.

In the laminated films of examples 10 to 6, the Young's modulus of the fragile processed portion was 2.2 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 3N/25 mm.

(examples 10 to 7)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that a PET film having a thickness of 16 μm was used as the outer layer dot, that HS varnish was formed on the entire surface of one surface of the PET film by printing using HS varnish, and that the surface provided with the ink layer in the outer layer and the inner layer were joined by a dry lamination process using a fatty acid ester-based adhesive for dry lamination.

In the laminated films of examples 10 to 7, the Young's modulus of the fragile processed portion was 2.2 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 0.05N/25 mm.

(examples 10 to 8)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that a PET film having a thickness of 25 μm was used as the outer layer and a CPP film having a Young's modulus of 0.27GPa was used as the inner layer.

In the laminated films of examples 10 to 8, the Young's modulus of the fragile processed portion was 2.6 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 3N/25 mm.

(examples 10 to 9)

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that: the surface provided with the HS paint layer in the outer layer and the inner layer were bonded by a dry lamination process using a fatty acid ester-based adhesive for dry lamination after forming the HS paint on the entire surface of one surface of the PET film by printing using the HS paint using a PET film having a thickness of 25 μm as the outer layer and a CPP film having a young's modulus of 0.27GPa as the inner layer.

In the laminated films of examples 10 to 9, the Young's modulus of the fragile processed portion was 2.6 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 0.05N/25 mm.

Comparative example 10-B

A laminated film and a packaging bag were produced in the same manner as in example 10-1, except that a PET film having a thickness of 25 μm was used as the outer layer and a CPP film having a Young's modulus of 0.45GPa was used as the inner layer.

In the laminate film of comparative example 10-B, the Young's modulus of the fragile processed portion was 2.8 GPa. Further, after the laminated film was left to stand at 80 ℃ for 2 minutes, the composite strength of the outer layer and the inner layer measured at 80 ℃ was 3N/25 mm.

Table 10 shows the results of the heating test performed on the packaging bags of examples 10-1 to 10-9 and comparative examples 10-A to 10-B in a microwave oven under the same conditions as those of the group of example 5.

[ Table 10]

As shown in Table 10, in examples 10-1, 10-2, 10-3, 10-6 and 10-8, the Young's modulus of the brittle processed portion of the LLDPE film was determined to be less than 2.8, and the composite strength was determined to be 0.1N/25mm or more, and a plurality of small holes were formed in the brittle processed portion upon heating, and steam was released to the outside of the packaging bag without causing cracking. In addition, the steam cooking can be performed while maintaining the inflated state of the packaging bag.

Further, in examples 10-4, 10-5, 10-7 and 10-9, the fragile worked portions were integrally formed into a large opening so as to prevent cracking.

In contrast, in comparative example 10-A, since no LLDPE film was used as the inner layer and the Young's modulus of the brittle processed portion was more than 2.0, the brittle processed portion cracked, causing cracking. Further, in comparative example 10-B, since the young's modulus of the fragile processed portion was 2.8 or more, the seal portion was broken.

While the embodiments and examples of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments, and the configurations of the embodiments may be combined by applying various changes and deletions to the respective components within the scope not departing from the gist of the present invention.

For example, the laminate film of the present invention can be used for a packaging container other than a packaging bag. Fig. 9 shows an example of a packaging container 101 in which a laminate film 10 is attached as a lid material to a container body 100 formed of paper or the like. As described above, when the packaging container 101 is heated in the microwave oven, steam can be appropriately released from the fragile processing portion 40 to prevent breakage and the like, and cooking can be performed.

The laminate film of the present invention can be produced by a so-called roll-to-roll method, while forming a fragile processed part and then rolling it into a roll shape. In this case, the direction in which the fragile processed portion extends may be parallel to the winding direction, but if the fragile processed portion is inclined to the winding direction, the fragile processed portion does not continue in the winding direction, and therefore, it is possible to appropriately prevent the generation of irregularities in the whole roll obtained by winding the laminate film. Therefore, storage, transportation, and the like can be appropriately performed.

Further, the embodiment of the fragile machined portion may be variously modified in addition to the above. For example, the fragile processed portion may be formed directly without removing the outer layer by so-called half-cut processing using a cutting tool such as a rotary die cutter. The shape of the fragile processed portion is not limited to a linear shape extending in one direction, and may be a linear shape having a bent or curved portion or a linear shape connecting a plurality of linear segments.

Description of the reference numerals

1 packaging bag (packaging container);

10. 51 laminating the film;

20. 20A outer layer;

30. 30A, 55 inner layer;

40a fragile processing part;

52 ink layer (middle layer);

56 strong composite layer (middle layer);

101 packaging the container.

Claims (5)

1. A laminate film, comprising:

an inner layer formed of a thermoplastic resin capable of being thermally welded,

an outer layer laminated to the inner layer,

a fragile worked portion at least a part of which is removed and at least a part of which is present, the shape in plan view being linear and having a Young's modulus of less than or equal to 2.0 gigapascals, and

an intermediate layer disposed between the inner layer and the outer layer,

the intermediate layer is an ink layer that reduces the composite strength between the inner layer and the outer layer, and is formed in a region other than the fragile processed portion and the periphery of the fragile processed portion in a plan view.

2. A laminate film, comprising:

an inner layer formed of a linear low density polyethylene resin and capable of being thermally welded,

an outer layer laminated to the inner layer,

a fragile worked portion having at least a part of the outer layer removed and at least a part of the inner layer present, a shape in a plan view being a linear shape and having a Young's modulus of less than 2.8 gigapascals, and an intermediate layer provided between the inner layer and the outer layer,

the intermediate layer is an ink layer that reduces the composite strength between the inner layer and the outer layer, and is formed in a region other than the fragile processed portion and the periphery of the fragile processed portion in a plan view.

3. The laminate film according to claim 1 or 2,

the composite strength of the portion near the fragile processing portion under a heating environment is 0.1N/25mm or more.

4. The laminate film according to claim 1 or 2,

the fragile processed portion is formed by laser irradiation.

5. A packaging container, characterized in that,

a laminate film according to claim 1 or 2 having a plurality of small holes formed in at least a part thereof on said fragile processed part when heated by a microwave oven.