JP6955735B2 - Laminated film and packaging method - Google Patents

Description

The present disclosure relates to laminated films and packaging methods.

Conventionally, a laminated film having a heat-sealing layer has been used as a packaging bag, a container, a lid material for a container, etc. used for applications such as foods, chemicals, industrial parts, miscellaneous goods, and magazines. These packaging bags and the like are manufactured by melt-bonding the heat-sealing layer of the laminated film.
Specifically, for example, in a packaging bag that houses bread, sweet buns, and the like as contents, the packaging bag is manufactured by melting and adhering with the heat seal layer inside. Further, when the contents are stored, an easy-open seal (a heat seal formed under heating conditions that enables opening while maintaining the shape of the bag) is provided at the opening of the packaging bag (for example, Patent Document). 1). A binding tool such as a plastic plate having a slit of about 2 cm square is usually used for binding the opening of the packaging bag for accommodating bread, sweet bun, and the like. Further, by providing the above-mentioned easy-to-open seal until the product such as bread and sweet bun reaches the consumer, it is possible to sufficiently prevent foreign substances that may enter through the gap of the binding tool.

JP-A-2002-193318

By the way, in the laminated film for forming the packaging bag as described above, it is easy to open that the temperature condition of the heat seal for obtaining the easy-opening seal of the packaging bag is a low temperature region and a relatively wide temperature range. It is preferable from the viewpoint of ease of forming a seal. Further, in the conventional laminated film as disclosed in Patent Document 1, it is said that the temperature condition of the heat seal can be set to a relatively wide temperature range. On the other hand, when the conventional laminated film is melt-bonded and cut (fused) in a high temperature region in order to form a packaging bag, the fusing portion may be peeled off, and it is required to have sufficient fusing seal strength. Was there.

Therefore, an object of the present disclosure is to provide a laminated film capable of easily forming an easy-to-open seal and sufficiently improving the strength of the fusing seal, and a packaging method.

As a result of diligent studies to solve the above problems, the present inventors have made a resin composition in which the heat-sealed layer of the laminated film contains a predetermined amount of a propylene-based resin and a thermoplastic elastomer of an ethylene-α-olefin copolymer. It has been found that the above-mentioned conventional problems can be solved by forming the material, and the present invention has been completed.
That is, the present invention is as follows.

[1] A laminated film having at least a heat-sealing layer, an intermediate layer, and a surface layer, one surface layer being a heat-sealing layer and the other surface layer being a surface layer.
The heat-sealed layer contains 50 to 90% by mass of the propylene-based resin and ethylene-1-butene with respect to 100% by mass of the total content of the propylene-based resin and the ethylene-1-butene copolymer rubber (EBR). Contains 10 to 50% by mass of copolymer rubber (EBR),
A laminated film, wherein the intermediate layer and the surface layer contain a propylene-based resin as a main resin component.
[2] The laminated film according to the above [1], wherein the propylene-based resin in the heat-sealing layer contains a propylene-based terpolymer.
[3] The laminated film according to any one of [1] and [2] above, wherein the propylene resin in the surface layer contains a propylene-ethylene random copolymer or a propylene terpolymer.
[4] The laminated film according to any one of [1] to [3] above, wherein the propylene-based resin in the intermediate layer contains a propylene homopolymer.
[5] The laminated film according to any one of [1] to [4] above, wherein the intermediate layer contains linear low-density polyethylene.
[6] The laminated film according to any one of [1] to [5] above, wherein the laminated film has a thickness of 20 to 50 μm.
[7] The laminated film according to any one of [1] to [6] above, wherein the heat seal layer has a thickness of 1.5 to 10 μm.
[8] Using the laminated film according to any one of the above [1] to [7], the heat-sealing layer is placed inside and melt-bonded to obtain a packaging bag, and the contents are stored inside the packaging bag. A packaging method in which the opening of the packaging bag is heat-sealed under heating conditions that allow the bag to be opened while maintaining the shape of the bag.

According to the present disclosure, it is possible to provide a laminated film capable of easily forming an easy-to-open seal and sufficiently improving the strength of the fusing seal, and a packaging method.

Hereinafter, a mode for carrying out the present disclosure (hereinafter, referred to as “the present embodiment”) will be described in detail.
It should be noted that the following embodiments are examples for explaining the present invention, and the present invention is not intended to be limited to the following contents. The present invention can be implemented with various modifications within the scope of the gist thereof.
Ordinal numbers (eg, first, second, third) in the present specification are used only to distinguish one element from another in order to avoid confusion of components. Therefore, the number of each component is not limited to the ordinal number.

[Laminated film]
The laminated film of the present embodiment is a laminated film having at least an intermediate layer, a heat seal layer laminated on one surface of the intermediate layer, and a surface layer laminated on the other surface of the intermediate layer. There,
The first resin composition forming the heat-sealing layer contains 50 to 90% by mass of the propylene-based resin with respect to 100% by mass of the total content of the propylene-based resin and the ethylene-1-butene copolymer rubber (EBR). %, Ethylene-1-butene copolymer rubber (EBR) is contained in an amount of 10 to 50% by mass.
The second resin composition forming the intermediate layer and the third resin composition forming the surface layer contain a propylene-based resin as a main resin component.
According to the laminated film of the present embodiment, it is easy to form an easy-to-open seal, and it is possible to sufficiently improve the fusing seal strength of the melt-bonded portion.

<Heat seal layer>
In the present embodiment, the heat seal layer is a layer that forms the other surface of the laminated film, specifically, the inner surface of the packaging bag, and is a propylene resin and an ethylene-1-butene copolymer rubber (EBR). ), 50 to 90% by mass of propylene resin and 10 to 50% by mass of ethylene-1-butene copolymer rubber (EBR) with respect to 100% by mass of the total content. Then, the heat seal layer can be formed from the first resin composition. Further, the first resin composition contains 50 to 90% by mass of the propylene resin and ethylene-90% by mass with respect to 100% by mass of the total content of the propylene resin and the ethylene-1-butene copolymer rubber (EBR). Contains 10 to 50% by mass of 1-butene copolymer rubber (EBR).
When the first resin composition or the heat seal layer has the above composition, the temperature condition for obtaining the easy-open seal of the packaging bag can be set to a relatively wide temperature range in a low temperature range. Since it can be made, it is easy to form an easy-to-open seal. In addition, since it is possible to sufficiently prevent the portion from being melt-bonded in the high temperature region from being peeled off due to cohesive fracture, the strength of the fusing seal can be sufficiently improved.

In the present embodiment, the heat-sealing layer or the first resin composition forming the heat-sealing layer contains a propylene-based resin. As a result, it is possible to secure the fusing seal strength when melt-bonding in a high temperature region.
The propylene resin is not particularly limited, and for example, a propylene homopolymer, a propylene-ethylene random copolymer, an ethylene-propylene block copolymer, a random copolymer of propylene and other α-olefins other than ethylene, and the like. Examples thereof include a propylene-based tarpolymer in which propylene, ethylene and 1-butene are copolymerized, and a propylene-based tarpolymer in which propylene, ethylene and diene are copolymerized.
Examples of the other α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-. 1 and the like may be mentioned, and two or more of these may be copolymerized at the same time. As the copolymerization type, either random copolymerization or block copolymerization can be used.
When the propylene-based resin contains a copolymer resin of a propylene monomer unit and another monomer unit, the content of the propylene monomer unit in the resin is the content of the other monomer unit. It is more than the amount and is the main component ratio. Specifically, the content of the propylene monomer unit in the copolymer resin is 80 mol% or more, preferably 90 mol% or more.
Moreover, these propylene-based resins may be used individually by 1 type or in combination of 2 or more types. The "monomer unit" means a repeating unit that forms a constituent unit of a polymer, and for example, a propylene monomer unit means a repeating unit (residue) of a propylene monomer in a polymer. ..

In the present embodiment, the propylene-based resin in the heat-seal layer includes, among the above, a propylene-based terpolymer, specifically, a propylene-based terpolymer in which propylene, ethylene and 1-butene are copolymerized, and propylene and ethylene. A propylene-based terpolymer in which diene is copolymerized is preferable, and a propylene-based terpolymer in which propylene, ethylene, and 1-butene are copolymerized is more preferable. By using a propylene-based terpolymer as the propylene-based resin, heat-sealing can be performed at a relatively low temperature, so that stable sealing strength can be obtained.
The propylene-based terpolymer has a propylene monomer unit content of 80 mol% or more, preferably 90 mol% or more.

In the present embodiment, the content of the propylene-based resin in the first resin composition is 50 to 100% by mass with respect to the total content of the propylene-based resin and the thermoplastic elastomer of the ethylene-α-olefin copolymer of 100% by mass. It is 90% by mass, preferably 55 to 80% by mass, and more preferably 60 to 70% by mass.
By setting the content to 50% by mass or more, the island phase derived from ethylene-1-butene copolymer rubber (EBR) does not become too large in the heat seal layer or the first resin composition, and the melt-bonded portion is formed. Since coagulation failure can be suppressed, the fusing seal strength can be improved. Further, by setting the content to 90% by mass or less, the EBR can be present in the heat seal layer or the first resin composition to some extent, so that an appropriate seal strength of the easy-open seal can be obtained and the seal strength thereof can be obtained. The formation conditions can be widened. Further, the content of the propylene-based resin with respect to the total amount (100% by mass) of the heat seal layer is also substantially in the same range as described above.

The melt flow rate of the propylene-based resin used for the heat seal layer is not particularly limited, but is preferably 2 to 20 g / 10 minutes, more preferably 4 to 15 g / 10 minutes, and further preferably 5 to 5 g. 10 g / 10 minutes. When the melt flow rate is 2 g / 10 minutes or more, the extrusion load is reduced and the discharge amount of the extruder can be increased, so that efficient production is possible and the melt flow rate is 20 g. When it is / 10 minutes or less, the melt viscosity does not become too low, and stable production can be performed.
In this embodiment, the melt flow rate can be a value measured at 190 ° C. or 230 ° C., 21.18N in accordance with JIS K7210.

The melting point of the propylene resin used for the heat seal layer is preferably 100 to 150 ° C, more preferably 110 to 145 ° C. When the melting point is 100 ° C. or higher, the heat resistance can be improved. Further, when the melting point is 150 ° C. or lower, heat sealing can be performed at a relatively low temperature, and stable sealing strength can be obtained. In this embodiment, the melting point is the endothermic peak temperature determined by a differential scanning calorimetry (DSC).

The density of the propylene resin used for the heat seal layer is not particularly limited, but is preferably ^{0.88 to 0.90 g / cm 3.}

In the present embodiment, the heat-sealing layer or the first resin composition forming the heat-sealing layer is an ethylene-, as a thermoplastic elastomer of an ethylene-α-olefin copolymer (hereinafter, also simply referred to as a thermoplastic elastomer). Contains 1-butene copolymer rubber (EBR). The ethylene-1-butene copolymer rubber is not sufficiently compatible with the above-mentioned propylene-based resin, and the phase structure of the first resin composition is a sea-island structure. However, by containing the thermoplastic elastomer, the ethylene-1-butene copolymer rubber has a sea-island structure. Since the ethylene-1-butene copolymer rubber, which is an island phase, mainly melts in a low temperature region, an easy-to-open seal having an appropriate sealing strength can be obtained. Further, since the ethylene-1-butene copolymer rubber has good dispersibility in the first resin composition, cohesive fracture is less likely to occur when melt-bonded, and the fusing seal strength can be improved. Further, since the ethylene-1-butene copolymer rubber has a lower melting point than the propylene-based resin, it is possible to widen the formation conditions while obtaining a more appropriate sealing strength of the easy-to-open seal.

The content of the butene monomer unit in the ethylene-1-butene copolymer rubber is not particularly limited, but is preferably 5 to 25 mol% with respect to all the monomer units.

In the present embodiment, the content of the ethylene-1-butene copolymer rubber in the first resin composition is 100% by mass based on the total content of the propylene resin and the ethylene-1-butene copolymer rubber. , 10 to 50% by mass, preferably 20 to 45% by mass, and more preferably 30 to 40% by mass.
When the content is 10% by mass or more, an appropriate sealing strength of the easy-opening seal can be obtained, and the formation conditions thereof can be broadened. Also, when the content is 50% by mass or less, the easy-opening seal can be easily opened. The seal strength does not become too high, and cohesive failure is less likely to occur when melt-bonded, so that the fusing seal strength can be ensured. Further, the content of the ethylene-1-butene copolymer rubber with respect to the total amount (100% by mass) of the heat seal layer is also substantially in the same range as described above.

In the present invention, the density of the ethylene-1-butene copolymer rubber is not particularly limited ^{, but is preferably 0.86 to 0.90 g / cm 3} , and more preferably 0.87 to 0.89 g / cm. It is ^3. By using an ethylene-α-olefin copolymer having a density in this range, an appropriate strength of an easily opened seal can be obtained.

In the present invention, the melt flow rate of the ethylene-1-butene copolymer rubber at 190 ° C. is not particularly limited, but is preferably 1 to 10 g / 10 minutes, more preferably 2 to 7 g / 10 minutes. Yes, more preferably 3-5 g / 10 minutes. When the melt flow rate is 1 g / 10 minutes or more, it can be dispersed well in the propylene resin, and when the melt flow rate is 10 g / 10 minutes or less, it is appropriate in the propylene resin. A sea-island structure can be formed.

In the present embodiment, the heat-sealing layer or the first resin composition may contain other thermoplastic resins or various additives such as antifogging agent, antistatic agent, heat stabilizer, nucleating agent, if necessary. Ingredients such as antioxidants, lubricants, antiblocking agents, mold release agents, and ultraviolet absorbers may be added as long as the object of the present invention is not impaired.
In the present embodiment, the total content of the propylene resin and the ethylene-1-butene copolymer rubber in the first resin composition is 95% by mass or more in 100% by mass of the first resin composition. Is preferable, more preferably 98% by mass or more, and even more preferably 100% by mass. Further, the total content of the propylene resin and the ethylene-1-butene copolymer rubber with respect to the total amount (100% by mass) of the heat seal layer is also substantially in the same range as described above.

In the present embodiment, the thickness (average thickness) of the heat seal layer is preferably 1.5 to 10 μm, more preferably 2 to 8 μm, and further preferably 4 to 6 μm. When the thickness is 1.5 μm or more, an appropriate adhesive force can be obtained, and when the thickness is 10 μm or less, a strong fusing seal strength can be obtained.
In the present embodiment, the thickness (average thickness) of each layer including the heat seal layer can be measured by observing the cross section at 3 to 5 points with an optical microscope and using the arithmetic mean value. ..

<Middle layer>
In the present embodiment, the intermediate layer is a layer formed between the heat seal layer and the surface layer, and contains a propylene-based resin as a main resin component. Further, the intermediate layer can be formed from the second resin composition. Then, the second resin composition contains a propylene-based resin as a main resin component.
When the second resin composition has the above composition, the strength of the packaging bag can be ensured.

In the present embodiment, the propylene-based resin in the intermediate layer is not particularly limited, but includes, for example, a propylene homopolymer, a propylene-ethylene random copolymer, an ethylene-propylene block copolymer, and propylene and an α-olefin other than ethylene. Examples thereof include a random copolymer of propylene, a propylene-based terpolymer in which propylene, ethylene and 1-butene are copolymerized, and a propylene-based terpolymer in which propylene, ethylene and diene are copolymerized.
Examples of other α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-pentene-1, 4-methyl-hexene-1. Etc., and two or more of these may be copolymerized at the same time. As the copolymerization type, either random copolymerization or block copolymerization can be used.
Moreover, these propylene-based resins may be used individually by 1 type or in combination of 2 or more types.
Among the above, the propylene-based resin preferably contains a propylene homopolymer, whereby the strength of the packaging bag can be further ensured.

In the present embodiment, the fact that the second resin composition contains a propylene-based resin as a main resin component means that when the second resin composition contains a plurality of resins, the second resin composition contains the largest amount of the propylene-based resin. means. The content of the propylene-based resin is preferably 50% by mass or more, more preferably 70% by mass or more, based on 100% by mass of the second resin composition. Further, the content of the propylene-based resin with respect to the total amount (100% by mass) of the intermediate layer is also substantially in the same range as described above.

The melt flow rate of the propylene-based resin in the intermediate layer is not particularly limited, but is preferably 2 to 20 g / 10 minutes, more preferably 4 to 15 g / 10 minutes, and further preferably 5 to 10 g / 10 minutes. Minutes. When the melt flow rate is 2 g / 10 minutes or more, the extrusion load is reduced and the discharge amount of the extruder can be increased, so that efficient production is possible and the melt flow rate is 20 g. When it is / 10 minutes or less, the melt viscosity does not become too low, and stable production can be performed.

Further, in the present embodiment, the intermediate layer or the second resin composition preferably contains linear low-density polyethylene. By containing the linear low-density polyethylene, suitable bag breakage resistance can be imparted.
When the second resin composition contains linear low-density polyethylene, the content is preferably 3 to 40 parts by mass, more preferably 5 with respect to 100 parts by mass of the propylene-based resin. It is ~ 30 parts by mass, more preferably 7 to 20 parts by mass. By setting the content in the above range, it is possible to impart more suitable rupture resistance while sufficiently ensuring the elasticity of the packaging bag. Further, the content of the linear low-density polyethylene in the intermediate layer is also substantially in the same range as described above.
Preferably the density of the linear low density polyethylene is less than 0.915 g / cm ^3, more preferably 0.910 g / cm ³ or less, and more preferably 0.907 g / cm ³ or less. Further, since it is easy to obtain a suitable fusing strength, the density ^{is preferably 0.890 g / cm 3} or more, and more preferably 0.895 g / cm ³ or more.

The melt flow rate of the linear low-density polyethylene is preferably 0.5 to 15 g / 10 minutes, more preferably 1.0 to 10 g / 10 minutes.

Further, in the intermediate layer or the second resin composition, other thermoplastic resins and various additives that can be contained in the above-mentioned heat seal layer or the first resin composition are not impaired the object of the present invention. It may be added in a range.

In the present embodiment, the thickness (average thickness) of the intermediate layer is preferably 5 to 40 μm, more preferably 7 to 35 μm, and further preferably 10 to 30 μm. By setting the thickness within the above range, the strength of the packaging bag can be appropriately ensured.

In the present embodiment, the melt flow rate of the second resin composition is not particularly limited, but is preferably 2 to 20 g / 10 minutes, more preferably 4 to 15 g / 10 minutes, and further preferably 5 10 g / 10 minutes. When the melt flow rate is 2 g / 10 minutes or more, the extrusion load is reduced and the discharge amount of the extruder can be increased, so that efficient production is possible and the melt flow rate is 20 g. When it is / 10 minutes or less, the melt viscosity does not become too low, and stable production can be performed.

<Surface layer>
In the present embodiment, the surface layer is a resin layer that forms one surface of the laminated film, specifically, the outer surface of the packaging bag, and contains a propylene-based resin as a main resin component. Further, the surface layer can be formed from the third resin composition. The third resin composition contains a propylene-based resin as a main resin component.
The propylene-based resin in the surface layer is not particularly limited. For example, the same resin as the propylene-based resin that can be used in the above-mentioned intermediate layer can be used for the surface layer. Therefore, as a specific example of the propylene-based resin in the surface layer, the example of the propylene-based resin that can be used in the intermediate layer described above is used.
When the propylene-based resin contains a copolymer resin of a propylene monomer unit and another monomer unit in the intermediate layer, the content of the propylene monomer unit in the copolymer resin is other. It is larger than the content of the monomer unit and is the main component ratio. Specifically, the content of the propylene monomer unit in the copolymer resin is 80 mol% or more, preferably 90 mol% or more.
Moreover, these propylene-based resins may be used individually by 1 type or in combination of 2 or more types.

In the present embodiment, the propylene-based resin that can be used for the surface layer includes, among the above-mentioned examples of the propylene-based resin, a propylene-ethylene random copolymer or a propylene-based terpolymer, specifically, propylene and ethylene. A propylene-based terpolymer in which 1-butene is copolymerized, a propylene-based terpolymer in which propylene, ethylene and diene are copolymerized, and the like are preferable, and a propylene-based terpolymer in which propylene, ethylene and 1-butene are copolymerized is more preferable. be.
By using a propylene-ethylene random copolymer or a propylene-based terpolymer as the propylene-based resin, stable gusset strength can be obtained.

In the present embodiment, the content of the propylene-based resin in the third resin composition is 50 to 100% by mass, preferably 70 to 100% by mass, based on 100% by mass of the third resin composition. More preferably, it is 90 to 100% by mass.
By setting the content to 50% by mass or more, the gusset strength can be strengthened, and the higher the content of the propylene-based resin, the higher the gusset strength tends to be. Further, the content of the propylene-based resin with respect to the total amount (100% by mass) of the surface layer is also substantially in the same range as described above.

The melt flow rate of the propylene-based resin used for the surface layer is not particularly limited, but is preferably 2 to 20 g / 10 minutes, more preferably 4 to 15 g / 10 minutes, and further preferably 5 to 10 g. / 10 minutes. When the melt flow rate is 2 g / 10 minutes or more, the extrusion load is reduced and the discharge amount of the extruder can be increased, so that efficient production is possible and the melt flow rate is 20 g. When it is / 10 minutes or less, the melt viscosity does not become too low, and stable production can be performed.

The melting point of the propylene-based resin used for the surface layer is preferably 100 to 150 ° C, more preferably 110 to 145 ° C. When the melting point is 100 ° C. or higher, the heat resistance can be improved. Further, when the melting point is 150 ° C. or lower, the fusing seal strength of the melt-bonded portion of the gusset portion can be improved when the packaging bag having the gusset portion is made by using the laminated film. In this embodiment, the melting point is the endothermic peak temperature determined by a differential scanning calorimetry (DSC).

The density of the propylene-based resin used for the surface layer is not particularly limited, but is preferably ^{0.88 to 0.91 g / cm 3.}

Further, in the surface layer or the third resin composition, other thermoplastic resins and various additives that can be contained in the above-mentioned heat seal layer or the first resin composition are not impaired the object of the present invention. It may be added in a range.

In the present embodiment, the thickness (average thickness) of the surface layer is preferably 1.5 to 10 μm, more preferably 2 to 8 μm, and further preferably 4 to 6 μm. By setting the thickness within the above range, it is possible to improve the fusing seal strength at the gusset portion when the laminated film is used to form a packaging bag having the gusset portion.

The laminated film of the present embodiment may be used as it is to produce, for example, a packaging bag, but for example, the surface of the surface layer can be printed to improve the product appeal of the contents, and the printing can be performed. It is also preferable to apply a surface treatment to the surface of the surface layer. Examples of such surface treatments include corona treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting. Corona treatment is preferable.

The laminated film may be provided with a layer other than the heat seal layer, the intermediate layer, and the surface layer described above.

<Characteristics of laminated film>
Here, in the present embodiment, the thickness (average thickness) of the laminated film is preferably 20 to 50 μm, more preferably 25 to 45 μm, and further preferably 30 to 40 μm. By setting the thickness within the above range, sufficient bag breakage resistance can be exhibited. In this embodiment, the thickness of the laminated film can be measured using a dial gauge.

In the present embodiment, the laminated film preferably has a heat seal strength in the range of 0.1 to 5 N / 15 mm, more preferably 0.2 to 4 N /, as measured under the conditions described in the column of Examples described later. It is 15 mm, more preferably 0.5 to 3 N / 15 mm. When the heat seal strength is in the above range, the seal strength of the easy-open seal of the packaging bag can be made suitable.

In the present embodiment, the laminated film preferably exhibits a wide temperature range when the heat seal strength measured under the conditions described in the column of Examples described later is in the range of 0.5 to 3N / 15 mm, for example. The temperature range preferably includes at least 90 to 130 ° C. When the temperature range in which the heat seal strength is in the range of 0.5 to 3N includes at least the above range, it is possible to preferably easily form an easy-to-open seal for the packaging bag.

Further, the laminated film preferably has a fusing seal strength in the range of 15 to 30 N / 15 mm, more preferably 16 to 30 N / 15 mm, further preferably 16 to 30 N / 15 mm, as measured under the conditions of a fusing blade of 300 ° C. and 120 sheets / minute. Is 17 to 30 N / 15 mm. When the fusing seal strength is within the above range, peeling of the fusing adhesive portion of the packaging bag can be sufficiently suppressed.

<Manufacturing method of laminated film>
The method for producing the laminated film of the present embodiment is not particularly limited, but for example, a method such as a coextrusion multilayer die method or a feed block method in which a resin or a resin mixture used for each layer is heated and melted by a separate extruder. Examples thereof include a coextrusion method in which the film is laminated in a molten state and then formed into a film by inflation, a T-die chill roll method, or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film having excellent hygiene and excellent cost performance can be obtained. Since the laminated film obtained by the production method is obtained as a substantially unstretched multilayer film, secondary molding such as deep drawing by vacuum forming is also possible.

<Use of laminated film>
The laminated film of the present embodiment is not particularly limited, and examples thereof include packaging bags, containers, and container lids used for applications such as foods, chemicals, industrial parts, miscellaneous goods, and magazines. Among them, it is preferable to use it as a packaging bag for storing bread, sweet buns and the like.

[Packaging bag]
The packaging bag of the present embodiment is obtained by using the above-mentioned laminated film of the present invention, and the heat-sealing layers of the laminated films are laminated and melt-bonded, or the surface layer and the heat-sealing layer are superposed and melted. It can be formed by bonding. In other words, in the packaging bag of the present embodiment, at least a part of the heat seal layer in the laminated film is arranged on the inner surface side (of the packaging bag), and at least a part of the surface layer is arranged on the outer surface side (of the packaging bag). It exists on the surface side, and there is a melt-bonded portion on at least a part of the outer surface (of the packaging bag).
As a specific packaging bag, a single laminated film in which the heat seal layer is bent inward is melt-bonded at both ends (in other words, both ends of the folded portion) in a direction substantially perpendicular to the bending direction. It can be a packaging bag having a portion, or a packaging bag formed by laminating a plurality of laminated films with at least one heat seal layer inside and melt-bonding them. If necessary, a gusset portion may be formed at a folded portion (also referred to as a bent portion) of the heat seal layer as described later. Further, it is also possible to form a packaging bag by sealing the end portion of the cylindrical laminated film formed from the roll-shaped laminated film by an automatic packaging machine and then sealing the upper and lower portions.
It is also possible to form a packaging bag / container by superimposing the heat-sealing layer of the above-mentioned laminated film and another heat-sealing film on the heat-sealing layer.

The packaging bag of the present embodiment includes a packaging bag having a melt-bonded portion in which one laminated film in which the heat seal layer is bent inward is melt-bonded at both ends in a direction substantially perpendicular to the bending direction. It is preferable, and more preferably, a packaging bag having a gusset portion at a folded portion (bottom portion) which is a crease of the heat seal layer.
Further, in the packaging bag of the present embodiment, for example, in a state after the contents are stored in the packaging bag, an easy-open seal can be formed in which the heat seal layers are heat-sealed at the opening of the packaging bag.

As the packaging bag of the present embodiment, as a method of manufacturing a packaging bag in which heat-sealing layers of laminated films are laminated and melt-bonded, specifically, the heat-sealing layer of the laminated film is bent so as to be inside. It can be obtained by melt-bonding and cutting the laminated film to a desired width. When the packaging bag has a gusset portion at the bottom, it is bent so that the heat seal layer of the laminated film is on the inside to form a bent portion (also referred to as a folded portion) and a pair of side surface portions. Then, while folding back the bent portion so as to be sandwiched between the pair of side surface portions, the vicinity of the bent portion of the pair of side surface portions is folded inward to form a gusset portion in which four layers of laminated films are stacked. It can be obtained by forming and melt-bonding and cutting (fusing) the laminated film to a desired width.

[Packaging method]
The packaging method of the present embodiment is a method of accommodating the contents by using the packaging bag according to the above-described embodiment of the present invention. Specifically, using the above-mentioned laminated film of the present invention, the heat-sealed layer of the laminated film is placed inside and melt-bonded to obtain a desired packaging bag, and then the contents are housed inside the packaging bag. The opening of the packaging bag is heat-sealed (forms an easy-to-open seal) under heating conditions that allow it to be opened while maintaining the shape of the bag.
At this time, it is preferable to adjust the fusing seal temperature and the bag making speed so that the fusing seal strength of the fusing portion is 7.5 N to 30 N / 15 mm, preferably 10 to 30 N / 15 mm.
Further, the heat seal strength of the easy-open seal is preferably 0.1 to 5 N / 15 mm, preferably 0.2 to 4 N / 15 mm.
Further, after forming the easy-to-open seal, the upper part of the bag may be sealed by binding with a binding tool such as a plastic plate, tape, or a string, if necessary.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples, and modifications can be made as appropriate.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Resin material>
The resin materials used in Examples and Comparative Examples are as follows.
(I) Propylene-ethylene-1-butene ternary copolymer (hereinafter, PP1): [Contains 4% by weight of ethylene monomer unit and 4% by weight of 1-butene monomer unit, density 0.9 g / Cm ³ , melt flow rate (hereinafter referred to as MFR) (230 ° C.) = 8 g / 10 min]
(II) Propylene-Ethylene Random Copolymer (PP2): [Ethylene monomer unit content 5% by weight, density 0.9 g / cm ³ , MFR (230 ° C) = 8 g / 10 min]
(III) Propylene homopolymer (hereinafter, PP3): [Density 0.9 g / cm ³ , MFR (230 ° C.) = 8 g / 10 min]
(IV) Ethylene-1-butene copolymer (hereinafter, EL1): [Density 0.88 g / cm ³ , MFR (190 ° C.) = 4 g / 10 min]
(V) Ethylene-1-octene copolymer (hereinafter, EL2): [Density = 0.88 g / cm ³ , MFR (190 ° C.) = 3 g / 10 min]
(VI) Ethylene-1-octene copolymer (hereinafter, EL3): [Density 0.90 g / cm ³ , MFR (190 ° C.) = 3 g / 10 min]

<Measurement and evaluation method>
The measurement and evaluation of the laminated films obtained in each Example and Comparative Example were carried out based on the following method.

(1) Evaluation of Fusing Seal Strength After half-folding the film with the heat-sealing layer of the laminated film obtained in Examples and Comparative Examples inside, a gusset is placed at the bottom, and the sealing temperature (bag making temperature) is 300 ° C. Bag making (bag making machine: HK-40 manufactured by Totani Giken Kogyo Co., Ltd., bag making speed: 120 sheets / minute) and bottom gusset bag (length: 345 mm (side part: 245 mm, gusset part:) 60 mm) and 235 mm in width) were produced. Using the five bottom gusset bags obtained, test pieces having a length of 70 mm and a width of 15 mm are formed from the center of the melt-bonded portion of the side portion other than the gusset portion, and the fusing seal portion serves as the central portion in the length direction. I cut out 10 pieces at a time. The maximum load when the 10 test pieces were pulled by a Tensilon tensile tester (manufactured by A & D Co., Ltd.) at 23 ° C. and a tensile speed of 300 mm / min was measured as the fusing strength. Then, the obtained fusing strength value was judged according to the following criteria.
Good: Fusing strength of both side parts is 15N / 15mm or more Defective: Fusing strength of at least one of the side parts is less than 15N / 15mm

(2) Evaluation of Ease of Forming Easy-Open Seal A bottom gusset bag was prepared in the same manner as in the above evaluation of fusing seal strength using the laminated films obtained in Examples and Comparative Examples. Heat sealer (manufactured by Tester Sangyo Co., Ltd .: pressure 0.2 MPa, time 1 second, seal temperature: upper seal bar 90 to 140) in a portion 50 mm below the upper end of the opening of the obtained bottom gusset bag in parallel with the opening. Heat-sealed at ° C., lower seal bar 50 ° C., seal bar shape: 300 m × 10 mm flat surface). From the heat-sealed portions of the five bottom gusset bags obtained, 10 test pieces each having a length of 70 mm and a width of 15 mm were cut out so that the heat-sealed portion was at the center in the width direction. The maximum load when the 10 test pieces were peeled off with a Tensilon tensile tester (manufactured by A & D Co., Ltd.) at 23 ° C. and a tensile speed of 300 mm / min was measured as the heat seal strength.
Then, by the above measurement method, the heat seal strength at intervals of 5 ° C. was measured between the heat seal temperatures of 80 ° C. and 140 ° C., and a calibration line showing the relationship between the heat seal strength and the heat seal temperature was created. Later, when the heat seal strengths were 0.5 and 3.0 N / 15 mm, the heat seal temperatures were T1 ° C. and T2 ° C., respectively, and the temperature difference ΔT was calculated from the calibration line. Then, the obtained numerical value of ΔT was judged according to the following criteria.
Good: ΔT is 8 ° C or higher Bad: ΔT is less than 8 ° C

(3) Evaluation of Rigidity The 1% secant modulus (unit: MPa) of the laminated films obtained in Examples and Comparative Examples at 23 ° C. was measured by Tensilon Tensile Tester [A & Co., Ltd.] based on ASTM D-882. -Made by Day] was used for measurement. The measurement was carried out in the extrusion direction (hereinafter referred to as "MD") and the film width direction (hereinafter referred to as "CD") at the time of film production.

(4) Evaluation of Impact Strength After holding the laminated films obtained in Examples and Comparative Examples in a thermostatic chamber adjusted to 0 ° C. for 6 hours, a spherical metallic impact head having a diameter of 1.5 inches was formed. The impact strength was measured by the film impact method. Then, the value of the obtained impact strength (J) was judged according to the following criteria.
Good: Impact strength is 0.20J or more Pass: Impact strength is 0.15J or more and less than 0.20J Fail: Impact strength is 0.10J or more and less than 0.15J Defective: Impact strength is less than 0.10J

Subsequently, Examples and Comparative Examples will be described.
(Example 1)
As the heat seal layer (A), a mixture consisting of 62% by weight of the propylene-ethylene-1-butene ternary copolymer (PP1) and 38% by weight of the ethylene-1-butene copolymer (EL1) was used. Further, as the intermediate layer (B), 50% by weight of the propylene homopolymer (PP3), 40% by weight of the propylene-ethylene random copolymer (PP2), and 10% by weight of the ethylene-1-octene copolymer (EL3) were used. A mixture was used. Further, as the surface layer (C), a propylene-ethylene-1-butene ternary copolymer (PP1) was used. The polymer used for each layer is supplied to three extruders so that the average thickness of the heat seal layer (A), the intermediate layer (B) and the surface layer (C) is 6 μm / 18 μm / 6 μm. It was extruded to form a three-layer film having a thickness of 30 μm.
The surface layer (C) of the obtained three-layer film was subjected to corona discharge treatment so that the surface energy of the surface layer (C) was 36 mN / m, and aged at 35 ° C. for 48 hours to obtain the film of Example 1. rice field.

(Examples 2 to 7)
As the heat seal layer (A), the intermediate layer (B) and the surface layer (C), a mixture having the resin composition shown in Table 1 below was used. Then, in the same manner as in Example 1, each mixture of the resin compositions used in each layer is supplied to three extruders, and the average of the heat seal layer (A), the intermediate layer (B), and the surface layer (C) is obtained. A three-layer film having a thickness of 30 μm was formed by coextrusion so that the thickness was 6 μm / 18 μm / 6 μm.
Then, the surface layer (C) of the obtained three-layer film was subjected to a corona discharge treatment so that the surface energy of the surface layer (C) was 36 mN / m, and aged at 35 ° C. for 48 hours. I got the film.

(Comparative Examples 1 to 7)
As the heat seal layer (A), the intermediate layer (B) and the surface layer (C), a mixture having the resin composition shown in Table 1 below was used. Then, in the same manner as in Example 1, the heat seal layer (A), the intermediate layer (B), and the surface layer (C) are co-extruded so that the average thickness is 6 μm / 18 μm / 6 μm, and the thickness is increased. A 30 μm three-layer film was molded.
Then, the surface layer (C) of the obtained three-layer film was subjected to corona discharge treatment so that the surface energy of the surface layer (C) was 36 mN / m, and aged at 35 ° C. for 48 hours in Comparative Examples 1 to 7. I got the film.
With respect to the films of Examples 1 to 7 and the films of Comparative Examples 1 to 7 obtained by the above method, the above-mentioned evaluation of the fusing seal strength, the evaluation of the ease of forming the easy-to-open seal, the evaluation of the rigidity, and the impact strength Evaluation was performed. The results are shown in Table 1 below.

上記表１の評価結果から、実施例１〜７のフィルムはいずれも、易開封シールを形成しやすく、且つ、優れた溶断シール強度を示す積層フィルムであることが確認された。

From the evaluation results in Table 1 above, it was confirmed that all of the films of Examples 1 to 7 were laminated films that easily formed an easy-to-open seal and exhibited excellent fusing seal strength.

According to the present disclosure, it is possible to provide a laminated film capable of easily forming an easy-to-open seal and sufficiently improving the strength of a fusing seal, and a packaging method.

Claims (7)

A laminated film having at least a heat-sealing layer, an intermediate layer, and a surface layer, one surface layer being a heat-sealing layer and the other surface layer being a surface layer.
The heat-sealed layer contains 50 to 90% by mass of the propylene-based resin and 50 to 90% by mass of the ethylene-1-butene with respect to 100% by mass of the total content of the propylene-based resin and the ethylene-1-butene copolymer rubber (EBR). Contains 10 to 50% by mass of polymer rubber (EBR),
Said intermediate layer and said surface layer has contains a propylene-based resin as a main resin component, and characterized that you containing said intermediate layer further linear low density polyethylene, laminated film. The laminated film according to claim 1, wherein the propylene-based resin in the heat-sealing layer contains a propylene-based terpolymer. The laminated film according to claim 1 or 2, wherein the propylene-based resin in the surface layer contains a propylene-ethylene random copolymer or a propylene-based terpolymer. The laminated film according to any one of claims 1 to 3, wherein the propylene-based resin in the intermediate layer contains a propylene homopolymer. The laminated film according to any one of claims 1 to 4 , wherein the laminated film has a thickness of 20 to 50 μm. The laminated film according to any one of claims 1 to 5 , wherein the heat seal layer has a thickness of 1.5 to 10 μm. Using the laminated film according to any one of claims 1 to 6, the heat-sealed layer is placed inside and melt-bonded to obtain a packaging bag, and the contents are stored inside the packaging bag and the packaging bag is provided. A packaging method in which the opening is heat-sealed under heating conditions that allow it to be opened while maintaining the shape of the bag.