JP2022019783A - Laminate and bag constituted of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate having heat resistance.

SOLUTION: A laminate includes at least a first oriented plastic film, a second oriented plastic film, a third oriented plastic film, and a sealant layer in this order. Each of the first oriented plastic film, the second oriented plastic film, and the third oriented plastic film contains a polyester as a main component.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a laminate and a bag composed of the laminate.

Conventionally, many cooked or semi-cooked liquids, viscous bodies, or contents in which liquids and solids are mixed and sealed in a bag made of a plastic laminate are on the market. In the bag, the unsealed portion in which the laminated bodies are not joined together constitutes the accommodating portion in which the contents are accommodated. Further, the sealing portion in which the laminated bodies are joined to each other seals the accommodating portion. The contents are cooked foods such as curry, stew and soup. The contents are heated in a microwave oven or the like while being contained in a bag.

By the way, when the contents contained in the sealed bag are heated by using a microwave oven, the water contained in the contents evaporates with the heating and the pressure in the containing portion increases. If the pressure in the bag housing increases, the bag may burst and the contents may scatter and stain the inside of the microwave oven. In consideration of such a problem, for example, Patent Document 1 proposes to provide a mechanism for automatically communicating the accommodating portion and the outside when the pressure of the accommodating portion increases and allowing the steam in the accommodating portion to escape to the outside. ing. Further, in Patent Document 1, in order to give the bag resistance to heating, as a laminate constituting the bag, a stretched polyethylene terephthalate film, a silica vapor-deposited stretched polyethylene terephthalate film, an alumina-deposited stretched polyethylene terephthalate film, a stretched nylon film, and a stretched film are used. It is proposed to use a polypropylene film, a polypropylene / ethylene-vinyl alcohol copolymer co-pressing co-stretched film, or a composite film in which two or more of these films are laminated.

JP-A-2015-120550

As a result of diligent research by the inventors of the present invention, it has been found that sufficient heat resistance may not be realized depending on the laminate constituting the conventional bag.

The present invention has been made in consideration of such a point, and an object of the present invention is to provide a laminate having heat resistance.

The present invention is a laminate, comprising at least a first stretched plastic film, a second stretched plastic film, a third stretched plastic film, and a sealant layer in this order, the first stretched plastic film, and the second stretched plastic film. The third stretched plastic film is an unstretched film containing polyester as a main component, and the sealant layer is an unstretched film containing a first thermoplastic resin and a second thermoplastic resin. The thermoplastic resin is composed of a propylene / ethylene block copolymer, the second thermoplastic resin contains at least an α-olefin copolymer or polyethylene, and the mass ratio of the first thermoplastic resin is the second. It is a laminated body having a higher mass ratio than that of the thermoplastic resin.

The laminate according to the present invention is formed between the first adhesive layer located between the first stretched plastic film and the second stretched plastic film, and between the second stretched plastic film and the third stretched plastic film. A second adhesive layer located may be further provided with a third adhesive layer located between the third stretched plastic film and the sealant layer.

In the laminate according to the present invention, the first adhesive layer, the second adhesive layer, and the third adhesive layer all contain a cured product of a polyol and an isocyanate compound, and have a thickness of 2 μm or more. You may be doing it.

In the laminate according to the present invention, the thickness of the first stretched plastic film, the second stretched plastic film, and the third stretched plastic film may be 9 μm or more and 25 μm or less.

The laminate according to the present invention may be for a microwave oven.

The present invention comprises the above-mentioned laminate having at least the first stretched plastic film, the second stretched plastic film, the third stretched plastic film, and the sealant layer in this order from the outer surface side to the inner surface side, and the above-mentioned laminate. It is a bag provided with a sealing portion for joining the inner surfaces of the laminated body to each other.

The bag according to the present invention may be provided with a steam venting mechanism.

According to the present invention, it is possible to provide a laminated body having heat resistance.

It is a front view which shows the bag in embodiment of this invention. It is sectional drawing which shows the case which the bag shown in FIG. 1 is seen along the line III-III. It is sectional drawing which shows an example of the layer structure of the laminated body which constitutes a bag. It is sectional drawing which shows an example of how the heat is transferred from the inner surface side to the outer surface side of a laminated body. It is a figure which shows an example of the measuring method of a piercing strength. It is a top view which shows the test piece for evaluating the impact strength. It is sectional drawing of the test piece shown in FIG. It is a figure which shows an example of the measuring method of the impact strength. It is a figure which shows the evaluation result of Examples 1 to 3 and Comparative Examples 1 and 2.

An embodiment of the present invention will be described with reference to FIGS. 1 to 4. In the drawings attached to the present specification, the scale, aspect ratio, etc. are appropriately changed from those of the actual product and exaggerated for the convenience of illustration and comprehension.

In addition, the terms such as "parallel", "orthogonal", and "identical" and the values of length and angle, etc., which specify the shape and geometric conditions and their degrees as used in the present specification, are strictly referred to. Without being bound by the meaning, we will interpret it including the range where similar functions can be expected.

FIG. 1 is a front view showing a bag 10 according to the present embodiment. The bag 10 includes an accommodating portion 17 for accommodating the contents. Note that FIG. 1 shows the bag 10 in a state before the contents are filled. The bag 10 according to the present embodiment is configured to be suitably used as a pouch for a microwave oven in which the contents are heated by a microwave oven.

As shown in FIG. 1, the bag 10 according to the present embodiment includes a steam venting mechanism 20 for releasing steam generated when heating the contents contained in the bag 10 to the outside. The steam bleeding mechanism 20 communicates the inside and the outside of the bag 10 with each other when the steam pressure exceeds a predetermined value to release the steam and suppresses the steam from escaping from a place other than the steam bleeding mechanism 20. ,It is configured. Hereinafter, the configuration of the bag 10 will be described.

Bag In the present embodiment, the bag 10 is a gusset-type bag configured to be self-supporting. The bag 10 includes an upper portion 11, a lower portion 12, and a side portion 13, and has a substantially rectangular contour in the front view. The names such as "upper part", "lower part" and "side part", and the terms "upper side" and "lower part" are based on the state in which the bag 10 stands on its own with the gusset part down. It is merely a relative representation of the position and direction of 10 and its components. The posture during transportation and use of the bag 10 is not limited by the names and terms in the present specification.

As shown in FIG. 1, the bag 10 includes a front surface film 14 constituting the front surface, a back surface film 15 constituting the back surface, and a lower film 16 constituting the lower portion 12. The lower film 16 is arranged between the front surface film 14 and the back surface film 15 in a state of being folded back at the folded-back portion 16f.

The terms "front surface film", "back surface film", and "lower film" described above are merely those in which each film is partitioned according to the positional relationship, and the method of providing the film when manufacturing the bag 10 is described. It is not limited by the above terms. For example, the bag 10 may be manufactured using one film in which the front surface film 14, the back surface film 15, and the lower film 16 are connected in series, or the bag 10 may be manufactured in one sheet in which the front surface film 14, the lower film 16 are connected in series. It may be manufactured using a total of two films, one film and one back surface film 15, and one front surface film 14, one back surface film 15, and one lower film 16 for a total of three films. It may be manufactured using.

The inner surfaces of the front surface film 14, the back surface film 15, and the lower film 16 are bonded to each other by a sealing portion. In the plan view of the bag 10 as shown in FIG. 1, the seal portion is hatched.

As shown in FIG. 1, the seal portion has an outer edge seal portion extending along the outer edge of the bag 10 and a steam vent seal portion 20a constituting the steam vent mechanism 20. The outer edge seal portion includes a lower seal portion 12a extending to the lower portion 12 and a pair of side seal portions 13a extending along the pair of side portions 13. In the bag 10 in a state before the contents are filled, as shown in FIG. 1, the upper portion 11 of the bag 10 is an opening 11b. After the contents are stored in the bag 10, the inner surface of the front surface film 14 and the inner surface of the back surface film 15 are joined at the upper portion 11 to form an upper sealing portion and seal the bag 10.

The side sealing portion 13a, the steam venting sealing portion 20a, and the upper sealing portion are sealing portions formed by joining the inner surface of the front surface film 14 and the inner surface of the back surface film 15.
On the other hand, the lower sealing portion 12a is formed by joining a sealing portion formed by joining the inner surface of the front surface film 14 and the inner surface of the lower film 16, and joining the inner surface of the back surface film 15 and the inner surface of the lower film 16. Includes a configured seal.

The method for forming the sealing portion is not particularly limited as long as the facing films can be joined to each other to seal the bag 10. For example, the inner surface of the film may be melted by heating and the inner surfaces may be welded to each other, that is, the seal portion may be formed by heat sealing. Alternatively, the sealing portion may be formed by adhering the inner surfaces of the opposing films to each other using an adhesive or the like.

Steam bleeding mechanism The configuration of the steam bleeding mechanism 20 will be described below. FIG. 2 is a cross-sectional view showing a case where the steam venting mechanism 20 of the bag 10 shown in FIG. 1 is viewed along the line II-II.

The steam venting seal portion 20a of the steam venting mechanism 20 has a shape that is easily peeled off as the pressure of the accommodating portion 17 increases. For example, the steam vent seal portion 20a has a shape protruding from the side seal portion 13a toward the inside of the bag 10. As a result, the force applied to the steam venting seal portion 20a when the pressure of the accommodating portion 17 increases can be made larger than the force applied to the side sealing portion 13a. Further, the width of the steam venting seal portion 20a is smaller than the width of the side sealing portion 13a. Further, as shown in FIGS. 1 and 2, a non-seal portion 20b is formed between the steam vent seal portion 20a and the outer edge of the side portion 13. As a result, it is possible to facilitate communication between the accommodating portion 17 and the outside due to the peeling of the seal portion in the steam venting seal portion 20a as compared with the side sealing portion 13a. The configuration and arrangement of the steam venting mechanism 20 are limited to the examples of FIGS. 1 and 2 as long as the accommodating portion 17 and the outside of the bag 10 can communicate with each other when the pressure of the accommodating portion 17 increases. There is no.

Layer structure of front surface film and back surface film Next, the layer structure of the front surface film 14 and the back surface film 15 will be described. FIG. 3 is a cross-sectional view showing an example of the layer structure of the laminate 30 constituting the front surface film 14 and the back surface film 15.

As shown in FIG. 3, the laminate 30 includes a first stretched plastic film 40, a first adhesive layer 45, a second stretched plastic film 50, a second adhesive layer 55, a third stretched plastic film 60, and a third adhesive. The agent layer 65 and the sealant layer 70 are provided at least in this order. The first stretched plastic film 40 is located on the outer surface 30y side, and the sealant layer 70 is located on the inner surface 30x side opposite to the outer surface 30y. The inner surface 30x is a surface located on the accommodating portion 17 side.

Hereinafter, each layer of the laminated body 30 will be described in detail.

(1st stretched plastic film)
The first stretched plastic film 40 is a plastic film stretched in a predetermined direction. The first stretched plastic film 40 functions as a base material layer for giving the laminated body 30 a predetermined strength. The first stretched plastic film 40 may be a uniaxially stretched film stretched in a predetermined unidirectional direction, or may be a biaxially stretched film stretched in a predetermined bidirectional direction. The stretching direction of the first stretched plastic film 40 is not particularly limited. For example, the first stretched plastic film 40 may be stretched in the direction in which the side portion 13 extends, or may be stretched in the direction orthogonal to the direction in which the side portion 13 extends. The draw ratio of the first stretched plastic film 40 is, for example, 1.05 times or more.

The first stretched plastic film 40 contains polyester as a main component. For example, the first stretched plastic film 40 contains 51% by mass or more of polyester. Examples of polyester include polyethylene terephthalate (hereinafter, also referred to as PET), polybutylene terephthalate (hereinafter, also referred to as PBT) and the like. The polyester of 51% by mass or more in the first stretched plastic film 40 may be composed of one kind of polyester or two or more kinds of polyester.

The thickness of the first stretched plastic film 40 is preferably 9 μm or more, more preferably 12 μm or more. The thickness of the first stretched plastic film 40 is preferably 25 μm or less, more preferably 20 μm or less. By making the thickness of the first stretched plastic film 40 9 μm or more, the first stretched plastic film 40 has sufficient strength. Further, by reducing the thickness of the first stretched plastic film 40 to 25 μm or less, the first stretched plastic film 40 exhibits excellent moldability. Therefore, the step of processing the laminated body 30 to manufacture the bag 10 can be efficiently performed.

An object of the present embodiment is to provide a laminated body 30 having heat resistance. As one of the methods for increasing the heat resistance of the laminated body 30, it is conceivable to configure each layer of the laminated body 30 by using a material having a thermal conductivity of a predetermined value or more. For example, the thermal conductivity of the material constituting the first stretched plastic film 40 is preferably 0.05 W / m · K or more, and more preferably 0.1 W / m · K or more. The thermal conductivity of PET is, for example, 0.14 W / m · K. Further, the thermal conductivity of PBT is higher than the thermal conductivity of PET, for example, 0.25 W / m · K.

The melting point of the first stretched plastic film 40 is preferably 200 ° C. or higher, more preferably 220 ° C. or higher. By setting the melting point of the first stretched plastic film 40 to 220 ° C. or higher, holes are formed in the first stretched plastic film 40 when the contents contained in the bag 10 manufactured by using the laminated body 30 are heated. In addition, it is possible to suppress the formation of wrinkles on the first stretched plastic film 40.

(First adhesive layer)
The first adhesive layer 45 contains an adhesive for adhering the first stretched plastic film 40 and the second stretched plastic film 50 by a dry laminating method. The adhesive constituting the first adhesive layer 45 is produced from an adhesive composition prepared by mixing a first composition containing a main agent and a solvent with a second composition containing a curing agent and a solvent. Specifically, the adhesive contains a cured product produced by the reaction of the main agent and the solvent in the adhesive composition.

Examples of the adhesive include polyurethane and the like. Polyurethane is a cured product produced by the reaction of a polyol as a main agent and an isocyanate compound as a curing agent. Examples of polyurethane include polyether polyurethane, polyester polyurethane and the like. The polyether polyurethane is a cured product produced by reacting a polyether polyol as a main agent with an isocyanate compound as a curing agent. Polyester polyurethane is a cured product produced by the reaction of a polyester polyol as a main agent and an isocyanate compound as a curing agent.

Examples of the isocyanate compound include aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI) and xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). The aliphatic isocyanate compound of the above, or an adduct or a multimer of the above-mentioned various isocyanate compounds can be used.

The material constituting the first adhesive layer 45 preferably has a higher thermal conductivity than the materials constituting the first stretched plastic film 40, the second stretched plastic film 50, the third stretched plastic film 60, and the sealant layer 70. Have. For example, the thermal conductivity of the material constituting the first adhesive layer 45 is preferably 1.0 W / m · K or more, and more preferably 3.0 W / m · K or more. The thermal conductivity of polyurethane is in the range of 3.0 W / m · K to 5.0 W / m · K, for example, 5.0 W / m · K. Due to the high thermal conductivity of the material constituting the first adhesive layer 45, when the bag 10 produced by using the laminated body 30 is heated, the heat generated in the accommodating portion 17 is generated by the inner surface 30x of the laminated body 30. While being transferred from the side to the outer surface 30y side, heat is easily diffused in the surface direction of the laminated body 30. As a result, the heat dissipation of the laminated body 30 can be improved, so that the temperature rise of the laminated body 30 can be suppressed. This makes it possible to prevent the laminate 30 from being damaged by heat when the bag 10 is heated. That is, the heat resistance of the laminated body 30 can be improved.

The thickness of the first adhesive layer 45 is preferably 2 μm or more, more preferably 3 μm or more. The thickness of the first adhesive layer 45 is preferably 6 μm or less, more preferably 5 μm or less. By setting the thickness of the first adhesive layer 45 to 3 μm or more, heat diffusion in the plane direction of the laminated body 30 is more likely to occur.

(Second stretched plastic film)
The second stretched plastic film 50 is a plastic film stretched in a predetermined direction, similarly to the first stretched plastic film 40. Like the first stretched plastic film 40, the second stretched plastic film 50 also functions as a base material layer for giving the laminated body 30 a predetermined strength. In addition to the configurations, materials and properties described below, the same configurations, materials and properties as those of the first stretched plastic film 40 can be adopted as the configurations, materials and properties of the second stretched plastic film 50.

The second stretched plastic film 50 also contains polyester as a main component, like the first stretched plastic film 40. For example, the second stretched plastic film 50 contains 51% by mass or more of polyester. Examples of polyester include PET, PBT and the like.

The thickness of the second stretched plastic film 50 is preferably 9 μm or more, more preferably 12 μm or more. The thickness of the second stretched plastic film 50 is preferably 25 μm or less, more preferably 20 μm or less. The thermal conductivity of the material constituting the second stretched plastic film 50 is preferably 0.05 W / m · K or more, and more preferably 0.1 W / m · K or more.

Other configurations, materials, properties, and the like of the second stretched plastic film 50 are the same as those of the first stretched plastic film 40.

(Second adhesive layer)
The second adhesive layer 55 contains an adhesive for adhering the second stretched plastic film 50 and the third stretched plastic film 60 by a dry laminating method. As an example of the adhesive of the second adhesive layer 55, polyurethane and the like can be mentioned as in the case of the first adhesive layer 45. In addition to the configurations, materials and properties described below, the same configurations, materials and properties as those of the first adhesive layer 45 can be adopted as the configurations, materials and properties of the second adhesive layer 55.

As the material constituting the second adhesive layer 55, similarly to the first adhesive layer 45, preferably, the first stretched plastic film 40, the second stretched plastic film 50, the third stretched plastic film 60 and the sealant layer 70 are used. It has a higher thermal conductivity than the constituent materials. For example, the thermal conductivity of the material constituting the second adhesive layer 55 is preferably 1.0 W / m · K or more, and more preferably 3.0 W / m · K or more.

The thickness of the second adhesive layer 55 is preferably 2 μm or more, more preferably 3 μm or more. The thickness of the second adhesive layer 55 is preferably 6 μm or less, more preferably 5 μm or less.

(Third stretched plastic film)
The third stretched plastic film 60 is a plastic film stretched in a predetermined direction, similarly to the first stretched plastic film 40. Like the first stretched plastic film 40, the third stretched plastic film 60 also functions as a base material layer for giving the laminated body 30 a predetermined strength. In addition to the configurations, materials and properties described below, the same configurations, materials and properties as those of the first stretched plastic film 40 can be adopted as the configurations, materials and properties of the third stretched plastic film 60.

The third stretched plastic film 60 also contains polyester as a main component, like the first stretched plastic film 40. For example, the third stretched plastic film 60 contains 51% by mass or more of polyester. Examples of polyester include PET, PBT and the like.

The thickness of the third stretched plastic film 60 is preferably 9 μm or more, more preferably 12 μm or more. The thickness of the third stretched plastic film 60 is preferably 25 μm or less, more preferably 20 μm or less. The thermal conductivity of the material constituting the third stretched plastic film 60 is preferably 0.05 W / m · K or more, and more preferably 0.1 W / m · K or more.

(Third adhesive layer)
The third adhesive layer 65 contains an adhesive for adhering the third stretched plastic film 60 and the sealant layer 70. As an example of the adhesive of the third adhesive layer 65, polyurethane and the like can be mentioned as in the case of the first adhesive layer 45. In addition to the configurations, materials and properties described below, the same configurations, materials and properties as those of the first adhesive layer 45 can be adopted as the configurations, materials and properties of the third adhesive layer 65.

As the material constituting the second adhesive layer 55, similarly to the first adhesive layer 45, preferably, the first stretched plastic film 40, the second stretched plastic film 50, the third stretched plastic film 60 and the sealant layer 70 are used. It has a higher thermal conductivity than the constituent materials. For example, the thermal conductivity of the material constituting the third adhesive layer 65 is preferably 1.0 W / m · K or more, and more preferably 3.0 W / m · K or more.

The thickness of the third adhesive layer 65 is preferably 2 μm or more, more preferably 3 μm or more. The thickness of the third adhesive layer 65 is preferably 6 μm or less, more preferably 5 μm or less.

By the way, as the isocyanate compound constituting the curing agent of the adhesive, as described above, there are aromatic isocyanate compounds and aliphatic isocyanate compounds. Of these, aromatic isocyanate compounds elute components that cannot be used in food applications in high-temperature environments such as heat sterilization. By the way, the third adhesive layer 65 is in contact with the sealant layer 70. Therefore, when the third adhesive layer 65 contains an aromatic isocyanate compound, the component eluted from the aromatic isocyanate compound adheres to the contents contained in the accommodating portion 17 in contact with the sealant layer 70. There is.

In consideration of such problems, a cured product produced by reacting a polyol as a main agent and an aliphatic isocyanate compound as a curing agent as an adhesive constituting the third adhesive layer 65 is preferable. Is used. This makes it possible to prevent components that cannot be used for food purposes from adhering to the contents due to the third adhesive layer 65.

(Relational expression)
Next, the relational expression established between the stretched plastic films 40, 50, 60 and the adhesive layers 45, 55, 65 will be described. In the laminated body 30, the following relational expression is preferably established.
A1 + A2 + A3 <B1 + B2 + B3
A1 is the product of the thickness of the first stretched plastic film 40 and the thermal conductivity.
A2 is the product of the thickness of the second stretched plastic film 50 and the thermal conductivity.
A3 is the product of the thickness of the third stretched plastic film 60 and the thermal conductivity.
B1 is the product of the thickness of the first adhesive layer 45 and the thermal conductivity.
B2 is the product of the thickness of the second adhesive layer 55 and the thermal conductivity.
B3 is the product of the thickness of the third adhesive layer 65 and the thermal conductivity.

The above relational expression means that the adhesive layers 45, 55, 65 have higher thermal conductivity in the plane direction of the laminated body 30 as compared with the stretched plastic films 40, 50, 60. As a result, when the contents contained in the bag 10 are heated, it is possible to prevent the laminated body 30 from being damaged by the influence of heat. Examples of damage caused to the laminated body 30 due to the influence of heat include holes in the laminated body 30 and wrinkles formed in the laminated body 30.

The reason why damage caused by heat can be suppressed by satisfying the above relational expression will be considered. The reason for such an action is not limited to the following considerations, and other considerations may be adopted.

FIG. 4 is a diagram showing how the contents 18 are attached to the inner surface 30x of the laminated body 30 constituting the bag 10. Adhesion of the content 18 to the inner surface 30x occurs, for example, when the content 18 contained in the bag 10 is heated by using a microwave oven, a part of the content 18 jumps and reaches the inner surface 30x. obtain. When the content 18 adhering to the inner surface 30x is further heated, the temperature of the laminated body 30 in contact with the content 18 also rises, and holes are formed in the laminated body 30 or wrinkles are formed in the laminated body 30. Can be considered.

Here, in the present embodiment, the laminated body 30 is configured so that the above-mentioned relational expression holds. Further, the laminate 30 includes three or more stretched plastic films 40, 50, 60 and an adhesive layer 45, 55, 65. Therefore, as shown in FIG. 4, while the heat generated in the content 18 is transferred from the inner surface 30x side to the outer surface 30y side of the laminated body 30, the heat is especially laminated in the adhesive layers 45, 55, 65. It becomes easy to diffuse in the plane direction of the body 30. As a result, heat is easily released to the outside of the bag 10, so that it is possible to suppress a temperature rise in the portion of the laminated body 30 to which the content 18 is attached. This makes it possible to prevent the laminated body 30 from being damaged by heat. That is, the heat resistance of the laminated body 30 can be improved.

B1 + B2 + B3 is preferably 3.5 times or more, more preferably 4.0 times or more, and further preferably 4.5 times or more of A1 + A2 + A3.

(Sealant layer)
Next, the sealant layer 70 will be described. As the material constituting the sealant layer 70, one or more resins selected from polyethylene such as low density polyethylene and linear low density polyethylene and polypropylene can be used. The sealant layer 70 may be a single layer or a multilayer. The sealant layer 70 is preferably made of an unstretched film. The term "unstretched" is a concept that includes not only a film that is not stretched at all but also a film that is slightly stretched due to the tension applied during film formation.

The bag 10 made of the laminated body 30 is subjected to sterilization treatment such as boiling treatment and retort treatment at a high temperature. Therefore, as the sealant layer 70, one having heat resistance to withstand these high temperature treatments is used.

The melting point of the material constituting the sealant layer 70 is preferably 150 ° C. or higher, more preferably 160 ° C. or higher. By increasing the melting point of the sealant layer 70, it becomes possible to carry out the retort treatment of the bag 10 at a high temperature, and therefore the time required for the retort treatment can be shortened. The melting point of the material constituting the sealant layer 70 is lower than the melting point of the resin constituting the stretched plastic films 40, 50, 60.

From the viewpoint of retort treatment, a material containing propylene as a main component can be used as the material constituting the sealant layer 70. Here, the material having propylene as a "main component" means a material having a propylene content of 90% by mass or more. Specific examples of the material containing propylene as a main component include a propylene / ethylene block copolymer, a propylene / ethylene random copolymer, polypropylene such as homopolypropylene, or a mixture of polypropylene and polyethylene. Can be done. Here, the "propylene / ethylene block copolymer" means a material having a structural formula represented by the following formula (I). Further, the "propylene / ethylene random copolymer" means a material having a structural formula represented by the following formula (II). Further, "homopolypropylene" means a material having a structural formula represented by the following formula (III).

When a mixture of polypropylene and polyethylene is used as the material containing propylene as a main component, the material may have a sea-island structure. Here, the "sea island structure" refers to a structure in which polyethylene is discontinuously dispersed in a region in which polypropylene is continuous.

From the viewpoint of boiling treatment, polyethylene, polypropylene, or a combination thereof can be mentioned as an example of the material constituting the sealant layer 70. Examples of polyethylene include medium-density polyethylene, linear low-density polyethylene, or a combination thereof. For example, from the viewpoint of the above-mentioned retort treatment, it is also possible to use the materials listed as the materials constituting the sealant layer 70. The material constituting the sealant layer 70 has a melting point of, for example, 100 ° C. or higher, more preferably 105 ° C. or higher, still more preferably 110 ° C. or higher. When polyethylene is used as the material constituting the sealant layer 70, a melting point of 100 ° C. or higher can be realized, for example, when the density of polyethylene is 0.920 g / cm ³ or higher. Specific examples of the sealant film for forming the sealant layer 70 having a melting point of 100 ° C. or higher include TUX-HC manufactured by Mitsui Chemicals Tocello, L6101 manufactured by Toyobo, and LS700C manufactured by Idemitsu Unitech. Specific examples of the sealant film for forming the sealant layer 70 having a melting point of 105 ° C. or higher include NB-1 manufactured by Tamapoli. Specific examples of the sealant film for forming the sealant layer 70 having a melting point of 110 ° C. or higher include LS760C manufactured by Idemitsu Unitech, TUX-HZ manufactured by Mitsui Chemicals Tocello, and the like.

Preferably, the sealant layer 70 is a monolayer film containing a propylene / ethylene block copolymer. For example, the sealant film containing the sealant layer 70 is a single-layer unstretched film containing a propylene / ethylene block copolymer as a main component. By using the propylene / ethylene block copolymer, the impact resistance of the sealant film can be enhanced, and thereby it is possible to prevent the bag 10 from being broken due to the impact at the time of dropping. In addition, the puncture resistance of the laminated body 30 can be improved.

Further, by using the propylene / ethylene block copolymer, the strength of the seal portion composed of the sealant layer 70 (hereinafter, also referred to as hot seal strength) at high temperature, for example, at 100 ° C. or higher, is low. For example, it is extremely small compared to the sealing strength at room temperature. For example, the hot seal strength at 100 ° C. is one-third or less, preferably one-fourth or less of the seal strength at 25 ° C. (hereinafter, also referred to as normal temperature seal strength). For example, the hot seal strength at a width of 15 mm at 100 ° C. is 30 N or less, preferably 25 N or less, more preferably 20 N or less, still more preferably 15 N or less. The normal temperature seal strength at a width of 15 mm at 25 ° C. is 23 N or more, preferably 40 N or more, more preferably 50 N or more, still more preferably 60 N or more. Due to the low hot seal strength, when the bag 10 is heated using a microwave oven, the steam venting seal portion 20a is easily peeled off, and the steam of the accommodating portion 17 is easily released to the outside of the bag 10. Therefore, it is possible to prevent the internal pressure of the accommodating portion 17 from becoming excessive, and thereby it is possible to prevent damage to the laminated body 30 during heating. Seal strength can be measured according to JIS Z1707 7.5. As the measuring instrument, for example, a tensile tester RTC-1310A with a constant temperature bath manufactured by Orientec can be used.

The propylene / ethylene block copolymer contains, for example, a sea component made of polypropylene and an island component made of an ethylene / propylene copolymer rubber component. The sea component can contribute to enhancing the blocking resistance, heat resistance, rigidity, sealing strength and the like of the propylene / ethylene block copolymer. In addition, the island component can contribute to enhancing the impact resistance of the propylene / ethylene block copolymer. Therefore, by adjusting the ratio of the sea component and the island component, the mechanical properties of the sealant film 70 containing the propylene / ethylene block copolymer can be adjusted.

In the propylene / ethylene block copolymer, the mass ratio of the sea component composed of polypropylene is higher than the mass ratio of the island component composed of the ethylene / propylene copolymer rubber component.
For example, in the propylene / ethylene block copolymer, the mass ratio of the sea component made of polypropylene is at least 51% by mass or more, preferably 60% by mass or more, and further preferably 70% by mass or more.

The single-layer sealant film 70 may further contain a second thermoplastic resin in addition to the first thermoplastic resin made of a propylene / ethylene block copolymer. Examples of the second thermoplastic resin include α-olefin copolymers and polyethylene. The α-olefin copolymer is, for example, linear low density polyethylene. Examples of polyethylene include low density polyethylene, medium density polyethylene, and high density polyethylene. The second thermoplastic resin can contribute to enhancing the impact resistance of the sealant film 70.

The low-density polyethylene is polyethylene having a density of 0.910 g / cm ³ or more and 0.925 g / cm ³ or less. The medium density polyethylene is polyethylene having a density of 0.926 g / cm ³ or more and 0.940 g / cm ³ or less. The high-density polyethylene is polyethylene having a density of 0.941 g / cm ³ or more and 0.965 g / cm ³ or less. Low-density polyethylene can be obtained, for example, by polymerizing ethylene at a high pressure of 1000 atm or more and less than 2000 atm. Medium-density polyethylene and high-density polyethylene can be obtained, for example, by polymerizing ethylene at medium pressure or low pressure of 1 atm or more and less than 1000 atm.

The medium-density polyethylene and the high-density polyethylene may partially contain a copolymer of ethylene and α-olefin. Further, even when ethylene is polymerized at medium pressure or low pressure, medium-density or low-density polyethylene can be produced when a copolymer of ethylene and α-olefin is contained. Such polyethylene is referred to as the above-mentioned linear low-density polyethylene. The linear low-density polyethylene is obtained by copolymerizing an α-olefin with a linear polymer obtained by polymerizing ethylene at medium pressure or low pressure to introduce a short chain branch. Examples of α-olefins include 1-butene (C ₄ ), 1-hexene (C ₆ ), 4-methylpentene (C ₆ ), 1-octene (C ₈ ) and the like.
The density of the linear low-density polyethylene is, for example, 0.915 g / cm ³ or more and 0.945 g / cm ³ or less.

The α-olefin copolymer constituting the second thermoplastic resin of the propylene / ethylene block copolymer is not limited to the above-mentioned linear low-density polyethylene. The α-olefin copolymer means a material having a structural formula represented by the following formula (IV).

Ｒ_１、Ｒ_２はいずれも、Ｈ（水素原子）、又はＣＨ_３、Ｃ_２Ｈ_５などのアルキル基である。また、ｊ及びｋはいずれも、１以上の整数である。また、ｊはｋよりも大きい。すなわち、式（IV）に示すα－オレフィン共重合体においては、Ｒ_１を含む左側の構造がベースとなる。Ｒ_１は例えばＨであり、Ｒ_２は例えばＣ_２Ｈ_５である。

Both R ₁ and R ₂ are H (hydrogen atom) or an alkyl group such as CH ₃ or C ₂ H ₅ . Further, both j and k are integers of 1 or more. Also, j is larger than k. That is, in the α-olefin copolymer represented by the formula (IV), the structure on the left side including _R1 is the base. R ₁ is, for example, H, and R ₂ is, for example, C ₂ H ₅ .

In the sealant film 70, the mass ratio of the first thermoplastic resin made of the propylene / ethylene block copolymer is higher than the mass ratio of the second thermoplastic resin containing at least the α-olefin copolymer or polyethylene. For example, in the single-layer sealant film 70, the mass ratio of the first thermoplastic resin made of a propylene / ethylene block copolymer is at least 51% by mass or more, preferably 60% by mass or more, and more preferably. It is 70% by mass or more.

As described above, the second thermoplastic resin can contribute to enhancing the impact resistance of the sealant film 70. Therefore, the mechanical properties of the sealant film 70 can be adjusted by adjusting the mass ratio of the second thermoplastic resin containing at least the α-olefin copolymer or polyethylene in the single-layer sealant film 70.

Further, the sealant layer 70 may further contain a thermoplastic elastomer. By using the thermoplastic elastomer, the impact resistance and the puncture resistance of the sealant layer 70 can be further improved.

The thermoplastic elastomer is, for example, a hydrogenated styrene-based thermoplastic elastomer. The hydrogenated styrene-based thermoplastic elastomer has a structure composed of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound. .. Further, the thermoplastic elastomer may be an ethylene / α-olefin elastomer. The ethylene / α-olefin elastomer is a low-crystalline or amorphous copolymer elastomer, which is a random copolymer of 50 to 90% by mass of ethylene as a main component and α-olefin as a copolymerization monomer. be.

The content of the propylene / ethylene block copolymer in the sealant layer 70 is, for example, 80% by mass or more, preferably 90% by mass or more.

Examples of the method for producing a propylene / ethylene block copolymer include a method of polymerizing raw materials such as propylene and ethylene using a catalyst. As the catalyst, a Ziegler-Natta type, a metallocene catalyst, or the like can be used.

The thickness of the sealant layer 70 is preferably 30 μm or more, more preferably 40 μm or more. The thickness of the sealant layer 70 is preferably 100 μm or less, more preferably 80 μm or less.

Hereinafter, preferable mechanical properties of the single-layer sealant film containing the propylene / ethylene block copolymer will be described.
The tensile elongation of the sealant film in the flow direction (MD) at 25 ° C. is preferably 600% or more and 1300% or less. The product of the tensile elongation (%) of the sealant film and the thickness (μm) of the sealant film in the flow direction (MD) is preferably 35,000 or more and 80,000 or less. The tensile elongation of the sealant film in the vertical direction (TD) at 25 ° C. is preferably 700% or more and 1400% or less. The product of the tensile elongation (%) of the sealant film and the thickness (μm) of the sealant film in the vertical direction (TD) is preferably 40,000 or more and 85,000 or less.
The tensile elastic modulus of the sealant film in the flow direction (MD) at 25 ° C. is preferably 400 MPa or more and 1100 MPa or less. The product of the tensile elastic modulus (MPa) of the sealant film and the thickness (μm) of the sealant film in the flow direction (MD) is preferably 30,000 or more and 55,000 or less. The tensile elastic modulus of the sealant film in the vertical direction (TD) at 25 ° C. is preferably 250 MPa or more and 900 MPa or less. The product of the tensile elastic modulus (MPa) of the sealant film and the thickness (μm) of the sealant film in the vertical direction (TD) is preferably 20,000 or more and 45,000 or more.

The tensile modulus and tensile elongation can be measured according to JIS K7127. As the measuring instrument, a tensile tester RTC-1310A with a constant temperature bath manufactured by Orientec can be used. In the bag 10 shown in FIG. 1, the direction in which the upper portion 11 and the lower portion 12 extend is the flow direction of the film constituting the bag 10 such as the sealant film, and the direction in which the side portion 13 extends is the sealant film or the like. , The vertical direction of the film constituting the bag 10. Although not shown, the bag 10 may be configured so that the direction in which the upper portion 11 and the lower portion 12 extend is the vertical direction of the film, and the direction in which the side portion 13 extends is the flow direction of the film.

There are mainly two types of single-layer sealant films containing propylene / ethylene block copolymers.
The first is a type having high tensile elongation and impact resistance, such as ZK500 described later. The first type of sealant film preferably also further comprises the property of low hot seal strength. As a result, it is possible to prevent the internal pressure of the accommodating portion 17 from becoming excessive when the bag 10 is heated, and it is possible to prevent damage to the laminated body 30.
The second is a type having a high tensile elastic modulus, such as ZK207 described later. By using the second type of sealant film, it is possible to enhance the tearability when the consumer tears the bag 10 along the first direction D1 to open the bag 10.

The product of the tensile elongation (%) of the first type sealant film and the thickness (μm) of the sealant film in the flow direction (MD) is preferably 45,000 or more, more preferably 50,000 or more, and 55,000 or more. Or it may be 60,000 or more. The product of the tensile elongation (%) of the first type sealant film and the thickness (μm) of the sealant film in the vertical direction (TD) is preferably 53000 or more, more preferably 60,000 or more. Since the sealant film has a high tensile elongation, it is possible to prevent the bag 10 from being broken due to an impact at the time of dropping or the like.
The product of the tensile elastic modulus (MPa) of the first type sealant film and the thickness (μm) of the sealant film in the flow direction (MD) is preferably 38,000 or less, more preferably 35,000 or less. The product of the tensile elastic modulus (MPa) of the first type sealant film and the thickness (μm) of the sealant film in the vertical direction (TD) is preferably 30,000 or less, more preferably 25,000 or less.

The product of the tensile elastic modulus (MPa) of the second type sealant film and the thickness (μm) of the sealant film in the flow direction (MD) is preferably 35,000 or more, more preferably 38,000 or more, still more preferably. It is over 45,000. The product of the tensile elastic modulus (MPa) of the second type sealant film and the thickness (μm) of the sealant film in the vertical direction (TD) is preferably 25,000 or more, more preferably 30,000 or more, and further. It is preferably 35,000 or more, and may be 38,000 or more. Since the sealant film has a high tensile elastic modulus, it is possible to improve the tearability when opening the bag 10.
The product of the tensile elongation (%) of the second type sealant film and the thickness (μm) of the sealant film in the flow direction (MD) is preferably 55,000 or less, more preferably 50,000 or less. The product of the tensile elongation (%) of the second type sealant film and the thickness (μm) of the sealant film in the vertical direction (TD) is preferably 60,000 or less, more preferably 55,000 or less.

(Other layers)
The laminate 30 may further include layers not shown in FIG. An example of a further layer will be described below.

The laminate 30 may further include a print layer. The printing layer is a layer provided on the laminated body 30 in order to show product information or give an aesthetic impression to the bag 10, and is printed on, for example, the first stretched plastic film 40. The print layer represents characters, numbers, symbols, figures, patterns, and the like. As a material constituting the print layer, an ink for gravure printing or an ink for flexographic printing can be used. As a specific example of the ink for gravure printing, a finale manufactured by DIC Graphics Co., Ltd. can be mentioned.

Further, the laminated body 30 may further include a transparent gas barrier layer. The transparent gas barrier layer includes at least a transparent vapor-deposited layer made of a transparent inorganic material formed on the surfaces of the stretched plastic films 40, 50, 60 and the like. Further, the transparent gas barrier layer may further include a transparent gas barrier coating film formed on the surface of the transparent vapor-deposited layer and having transparency.

The transparent thin-film deposition layer functions as a layer having a gas barrier function of blocking the permeation of oxygen gas, water vapor, and the like. In addition, two or more transparent vapor deposition layers may be provided. When two or more transparent vapor-deposited layers are provided, they may have the same composition or different compositions. Examples of the method for forming the transparent vapor deposition layer include a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, and an ion plating method, or a plasma chemical vapor deposition method, heat. Examples thereof include a chemical vapor deposition method, a chemical vapor deposition method such as a photochemical vapor deposition method, and a CVD method. Specifically, a thin-film deposition film film forming apparatus can be used to form a thin-film deposition layer on the film-forming roller. Examples of the inorganic material constituting the transparent thin-film vapor layer include aluminum oxide (aluminum oxide) and silicon oxide. The thickness of the transparent thin-film deposition layer is preferably 40 Å or more and 130 Å or less, and more preferably 50 Å or more and 120 Å or less.

The transparent gas barrier coating film is a layer that functions as a layer that suppresses permeation of oxygen gas, water vapor, and the like. The transparent gas barrier coating film 37 has a general formula of R ¹ _n M (OR ² ) _m (however, in the formula, R ¹ and R ² represent organic groups having 1 to 8 carbon atoms, and M represents a metal atom. , N represents an integer of 0 or more, m represents an integer of 1 or more, and n + m represents the valence of M.) At least one or more alkoxides and the polyvinyl alcohol as described above. With a transparent gas barrier composition containing a le-based resin and / or an ethylene / vinyl alcohol copolymer, which is polycondensed by the solgel method in the presence of a solgel method catalyst, acid, water, and an organic solvent. can get.

Layer structure of the lower film Next, the layer structure of the lower film 16 will be described.

The layer structure of the lower film 16 is arbitrary as long as it has an inner surface that can be bonded to the inner surface of the front surface film 14 and the inner surface of the back surface film 15. For example, similarly to the front surface film 14 and the back surface film 15, the above-mentioned laminate 30 may be used as the lower film 16. Alternatively, a film having an inner surface composed of a sealant layer and having a structure different from that of the laminated body 30 may be used as the lower film 16.

Method for Manufacturing Laminated Body Next, an example of a method for manufacturing the laminated body 30 will be described.

First, the first stretched plastic film 40 and the second stretched plastic film 50 described above are prepared. Subsequently, the first stretched plastic film 40 and the second stretched plastic film 50 are laminated via the first adhesive layer 45 by the dry laminating method. Then, by the dry laminating method, the laminate containing the first stretched plastic film 40 and the second stretched plastic film 50 and the third stretched plastic film 60 are laminated via the second adhesive layer 55. Then, a laminate containing the first stretched plastic film 40, the second stretched plastic film 50, and the third stretched plastic film 60, and the sealant film for forming the sealant layer 70 are passed through the third adhesive layer 65. Stack.
As a result, the laminate 30 including the first stretched plastic film 40, the second stretched plastic film 50, the third stretched plastic film 60, and the sealant layer 70 can be obtained.

The order in which the first stretched plastic film 40, the second stretched plastic film 50, the third stretched plastic film 60, and the sealant layer 70 are laminated by the dry laminating method is not limited to the above-mentioned order. For example, the first laminated body including the first stretched plastic film 40 and the second stretched plastic film 50 and the second laminated body including the third stretched plastic film 60 and the sealant layer 70 are laminated by a dry laminating method. 30 may be manufactured.

In the dry laminating method, first, the adhesive composition is applied to one of the two films to be laminated. Subsequently, the applied adhesive composition is dried to volatilize the solvent.
Then, the two films are laminated via the dried adhesive composition. Subsequently, the two laminated films are wound and aged for 24 hours or more in an environment of, for example, 20 ° C. or higher.

Method for manufacturing a bag Next, a method for manufacturing a bag 10 using the above-mentioned laminated body 30 will be described. First, the front surface film 14 and the back surface film 15 made of the laminated body 30 are prepared. Further, the folded lower film 16 is inserted between the front surface film 14 and the back surface film 15. Subsequently, the inner surfaces of the films are heat-sealed to form a sealing portion such as a lower sealing portion 12a and a side sealing portion 13a. Further, the films bonded to each other by heat sealing are cut into an appropriate shape to obtain the bag 10 shown in FIG. Subsequently, the contents 18 are filled in the bag 10 through the opening 11b of the upper portion 11. The content 18 is a cooked food containing water, such as curry, stew, and soup. Further, the content 18 may have a material containing a large amount of oil, such as a seasoning such as meat, fish and miso. In addition to food, food that can be heated by a water bath or the like can be stored in the bag 10 as a content. After that, the upper portion 11 is heat-sealed to form the upper seal portion. In this way, the bag 10 in which the contents 18 are housed and sealed can be obtained.

Method of heating contents Next, an example of a method of heating the contents 18 contained in the bag 10 will be described.

First, the bag 10 is placed inside the microwave oven with the lower portion 12 facing down and the bag 10 standing on its own. Next, the contents are heated using a microwave oven. As a result, the temperature of the content 18 rises, and along with this, the water contained in the content 18 evaporates and the pressure of the accommodating portion 17 increases.

When the pressure of the accommodating portion 17 becomes high, the front surface film 14 and the back surface film 15 swell outward due to the force received from the accommodating portion 17. Here, in the present embodiment, the laminate 30 constituting the front surface film 14 and the back surface film 15 includes three stretched plastic films 40, 50, 60. Therefore, the rigidity of the laminated body 30 is high, and as a result, it is possible to prevent the front surface film 14 and the back surface film 15 from stretching when the front surface film 14 and the back surface film 15 are subjected to a force. As a result, the force generated by the pressure generated in the accommodating portion 17 can be mainly used not as a force for stretching the front surface film 14 and the back surface film 15, but as a force for peeling off the steam venting seal portion 20a. can. Therefore, the force applied to the steam vent seal portion 20a can be increased. As a result, the steam venting seal portion 20a is easily peeled off during heating, and the steam of the accommodating portion 17 can be released to the outside via the steam venting mechanism 20.

Further, according to the present embodiment, as described above, the laminated body 30 has heat resistance. Therefore, it is possible to suppress the formation of holes in the laminated body 30 and the formation of wrinkles in the laminated body 30 during heating.

Further, according to the present embodiment, as described above, the laminate 30 includes at least three stretched plastic films 40, 50, 60. Therefore, the bag 10 composed of the laminated body 30 and the laminated body 30 can be provided with puncture resistance. The piercing strength of the laminate 30 is preferably 10 N or more, more preferably 11 N or more, further preferably 12 N or more, and particularly preferably 13 N or more or 14 N or more.

Further, according to the present embodiment, as described above, the product of the tensile elongation (%) and the thickness (μm) of the sealant film constituting the sealant layer 70 of the laminated body 30 in the flow direction (MD) is 45,000. As described above, the product of the tensile elongation (%) and the thickness (μm) in the vertical direction is 53000 or more. Thereby, the impact strength of the laminated body 30 can be increased. This makes it possible to improve the impact resistance of the bag 10 made of the laminated body 30. For example, it is possible to prevent the bag 10 from breaking due to the impact at the time of dropping. The impact strength of the laminated body 30 is preferably 600 kJ / m or more, more preferably 700 kJ / m or more, and even more preferably 800 kJ / m or more.

It is possible to make various changes to the above-described embodiment. Hereinafter, modification examples will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding portions in the above-described embodiment will be used for the portions that can be configured in the same manner as in the above-described embodiment. Duplicate explanations will be omitted. Further, when it is clear that the action and effect obtained in the above-described embodiment can be obtained in the modified example, the description thereof may be omitted.

(Modification example of bag)
In the above-described embodiment, the example in which the bag 10 is a gusset type bag is shown, but the specific configuration of the bag 10 is not particularly limited. For example, the bag 10 may be a so-called four-sided seal bag formed by joining the inner surfaces of the front surface film 14 and the back surface film 15 made of the laminated body 30 to each other at the upper portion 11, the lower portion 12, and the side portion 13.

Further, in the above-described embodiment, an example of heating the contents 18 contained in the bag 10 using a microwave oven has been shown, but the present invention is not limited to this. For example, the contents 18 contained in the bag 10 may be heated by boiling water. In this case, the bag 10 does not have to be provided with the above-mentioned steam venting mechanism 20.

(Other aspects)
Another aspect of the present invention is a laminate, comprising at least a first stretched plastic film, a second stretched plastic film, a third stretched plastic film and a sealant layer in this order, the first stretched plastic film, the first stretched plastic film, the first. Both the 2-stretched plastic film and the third stretched plastic film are laminates containing polyester as a main component.

The laminate according to another aspect of the present invention comprises a first adhesive layer located between the first stretched plastic film and the second stretched plastic film, and the second stretched plastic film and the third stretched plastic film. A second adhesive layer located between the first adhesive layer and a third adhesive layer located between the third stretched plastic film and the sealant layer are further provided, and the first adhesive layer and the second adhesive layer are further provided. Both the adhesive layer and the third adhesive layer may contain a cured product of a polyol and an isocyanate compound and may have a thickness of 2 μm or more.

In the laminate according to another aspect of the present invention, the product of the thickness and the thermal conductivity of the first stretched plastic film is A1, and the product of the thickness and the thermal conductivity of the second stretched plastic film is A2. The product of the thickness of the stretched plastic film and the thermal conductivity is A3, the product of the thickness of the first adhesive layer and the thermal conductivity is B1, and the product of the thickness of the second adhesive layer and the thermal conductivity is B2. When the product of the thickness of the third adhesive layer and the thermal conductivity is B3, the following equation may be established.
A1 + A2 + A3 <B1 + B2 + B3

In the laminate according to another aspect of the present invention, the sealant layer may contain polypropylene.

In the laminate according to another aspect of the present invention, the sealant layer may contain a propylene / ethylene block copolymer.

Another aspect of the present invention is a bag comprising a laminate including an outer surface and an inner surface and a sealing portion for joining the inner surfaces of the laminate, and the laminate is from the outer surface side to the inner surface side. The first stretched plastic film, the second stretched plastic film, the third stretched plastic film, and the sealant layer are provided in this order at least, and the first stretched plastic film, the second stretched plastic film, and the third stretched plastic film are provided in this order. Both are bags containing polyester as a main component.

According to another aspect of the present invention, it is possible to provide a laminate having heat resistance.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the description of the following Examples as long as the gist of the present invention is not exceeded.

First, the piercing strength, impact strength and heat resistance of the laminated body 30 in the present invention were evaluated according to Examples 1 and 2 and Comparative Examples 1 and 2.

(Example 1)
A stretched PET film having a thickness of 12 μm was prepared as the first stretched plastic film 40, the second stretched plastic film 50, and the third stretched plastic film 60, respectively. Further, as a film for forming the sealant layer 70, an unstretched polypropylene film ZK500 manufactured by Toray Film Processing Co., Ltd. was prepared. ZK500 contains the above-mentioned propylene / ethylene block copolymer and elastomer. The thickness of the sealant layer 70 was 60 μm.

ZK500 has a higher tensile elongation as compared with a general unstretched polypropylene film. Specifically, the tensile elongation of ZK500 in the flow direction (MD) is 1180% when the thickness is 50 μm and 1100% when the thickness is 60 μm. The tensile elongation of ZK500 in the vertical direction (TD) is 1240% when the thickness is 50 μm and 1150% when the thickness is 60 μm. Therefore, the product of the tensile elongation (%) and the thickness (μm) of ZK500 in the flow direction is 59000 when the thickness is 50 μm and 66000 when the thickness is 60 μm. The product of the tensile elongation (%) and the thickness (μm) of the ZK500 in the vertical direction is 62000 when the thickness is 50 μm and 69000 when the thickness is 60 μm.

Further, ZK500 has a lower tensile elastic modulus than a general unstretched polypropylene film. Specifically, the tensile elastic modulus of the ZK500 in the flow direction (MD) is 640 MPa when the thickness is 50 μm and 550 MPa when the thickness is 60 μm. The tensile elastic modulus of the ZK500 in the vertical direction (TD) is 480 MPa when the thickness is 50 μm and 400 MPa when the thickness is 60 μm. Therefore, the product of the tensile elastic modulus (MPa) and the thickness (μm) of the ZK500 in the flow direction is 32000 when the thickness is 50 μm and 33000 when the thickness is 60 μm. The product of the tensile elastic modulus (MPa) and the thickness (μm) of the ZK500 in the vertical direction is 24,000 when the thickness is 50 μm and 35,000 when the thickness is 60 μm.

Subsequently, the first stretched plastic film 40, the second stretched plastic film 50, the third stretched plastic film 60, and the sealant layer 70 were laminated by a dry laminating method to prepare a laminated body 30. The first adhesive layer 45, the second adhesive layer 55, and the third adhesive layer 65 are two-component polyurethane adhesives manufactured by Rock Paint Co., Ltd. (main agent: RU-40, curing agent: H-4). Was used. The main agent, RU-40, is a polyester polyol. The thickness of the first adhesive layer 45, the second adhesive layer 55, and the third adhesive layer 65 was 3.5 μm.

[Evaluation of piercing resistance]
Subsequently, the piercing strength of the laminated body 30 was measured according to JIS Z1707 7.4. As a measuring instrument, a Tencilon universal material testing machine RTC-1310 manufactured by A & D was used.
Specifically, as shown in FIG. 5, a semi-circular needle 90 having a diameter of 1.0 mm and a tip shape radius of 0.5 mm from the outer surface 30y side with respect to the test piece of the laminated body 30 in a fixed state. Was pierced at a speed of 50 mm / min (50 mm per minute), and the maximum value of stress until the needle 90 penetrated the laminate 30 was measured. The maximum value of stress was measured for 5 or more test pieces, and the average value was taken as the piercing strength of the laminated body 30. The environment at the time of measurement was a temperature of 23 ° C. and a relative humidity of 50%. As a result, the piercing strength was 14.1N.

[Evaluation of impact resistance]
Subsequently, the two laminated bodies 30 were stacked and heated at 190 ° C. for 1 second, and the inner surfaces 30x of the laminated bodies 30 were heat-sealed. Next, two heat-sealed laminates 30 were cut out with a width of 15 mm to prepare a test piece 100. FIG. 6 is a plan view showing the test piece 100, and FIG. 7 is a cross-sectional view of the test piece 100 of FIG. The test piece 100 has a width W3 of 15 mm and a length W4 of 50 mm, and a seal portion 101 is formed over a length W5 of 10 mm from one end and a length of 40 mm from the other end. The seal portion is not formed. Subsequently, as shown in FIG. 8, the unsealed portion of one laminated body 30 and the unsealed portion of the other laminated body 30 are oriented in opposite directions in a direction orthogonal to the surface direction of the sealed portion 101. That is, after making it into a T-shape, the end of the unsealed portion of one laminated body 30 and the end of the unsealed portion of the other laminated body 30 are each set to the jig 102. , 103. At this time, the distance T between the jigs 102 and 103 in the direction orthogonal to the surface direction of the seal portion 101 was set to 40 mm. Subsequently, when one jig 102 is hit with a hammer 104 from the surface of one laminated body 30 on the first stretched plastic film 40 side to separate the one laminated body 30 and the other laminated body 30. Impact strength was measured. As a measuring instrument, a digital impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used for evaluation. As a hammer for applying an impact to the test piece 100, a hammer of 2J was used. As a result, the impact strength was 843 kJ / m.

[Evaluation of heat resistance]
Subsequently, a bag 10 was produced using the laminated body 30, and the heat resistance of the bag 10 was evaluated. Specifically, first, the bag 10 shown in FIG. 1 was manufactured using the laminated body 30. The height S1 of the bag 10 was 145 mm, and the width S2 was 140 mm. Further, the height S3 of the folded lower film 16, that is, the height from the lower end portion of the bag 10 to the folded portion 16f was 40 mm. In the following description, the bag 10 having a height S1 of 145 mm, a width S2 of 140 mm, and a height S3 of 40 mm is also referred to as an S size bag 10. Subsequently, 100 g of a content containing a large amount of oil such as meat and miso was filled inside the bag 10, and the upper portion 11 was heat-sealed to form an upper seal portion.

Then, the bag 10 containing the contents was heated for 2 minutes using a microwave oven having an output of 500 W, and it was confirmed whether or not the laminate 30 constituting the bag 10 was damaged. The test was performed on 10 bags 10. As a result, it was confirmed that in 10 of the 10 bags 10, no damage such as holes in the laminated body 30 or wrinkles formed in the laminated body 30 occurred.

(Example 2)
A bag 10 was prepared using the same laminate 30 as in the case of Example 1, and the heat resistance of the bag 10 was evaluated. The height S1 of the bag 10 was 145 mm, the width S2 was 150 mm, and the height S3 of the folded lower film 16 was 43 mm. In the following description, the bag 10 having a height S1 of 145 mm, a width S2 of 150 mm, and a height S3 of 43 mm is also referred to as an M size bag 10. Subsequently, as in the case of Example 1, 100 g of the contents containing a large amount of oil was filled inside the bag 10, and the upper portion 11 was heat-sealed to form the upper seal portion.

Then, as in the case of Example 1, the bag 10 containing the contents is heated for 2 minutes using a microwave oven having an output of 500 W, and whether or not the laminate 30 constituting the bag 10 is damaged. I confirmed that. As a result, it was confirmed that in 10 of the 10 bags 10, no damage such as holes in the laminated body 30 or wrinkles formed in the laminated body 30 occurred.

(Example 3)
The laminated body 30 was produced in the same manner as in Example 1 except that the unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used as the sealant film for forming the sealant layer 70. The thickness of the unstretched polypropylene film ZK207 was 70 μm.

ZK207 has a higher tensile modulus than ZK500. Specifically, the tensile elastic modulus of ZK207 in the flow direction (MD) is 780 MPa when the thickness is 50 μm and 680 MPa when the thickness is 60 μm. The tensile elastic modulus of ZK207 in the vertical direction (TD) is 630 MPa when the thickness is 50 μm and 560 MPa when the thickness is 60 μm. Therefore, the product of the tensile elastic modulus (MPa) and the thickness (μm) of ZK207 in the flow direction is 39000 when the thickness is 50 μm and 40800 when the thickness is 60 μm. The product of the tensile elastic modulus (MPa) and the thickness (μm) of ZK207 in the vertical direction is 31500 when the thickness is 50 μm and 33600 when the thickness is 60 μm. By using ZK207, the tearability of the laminated body 30 and the bag 10 including the laminated body 30 can be enhanced.

Further, ZK207 has a lower tensile elongation than ZK500. Specifically, the tensile elongation of ZK207 in the flow direction (MD) is 790% when the thickness is 50 μm and 730% when the thickness is 60 μm. The tensile elongation of ZK207 in the vertical direction (TD) is 1020% when the thickness is 50 μm and 870% when the thickness is 60 μm. Therefore, the product of the tensile elongation (%) and the thickness (μm) of ZK207 in the flow direction is 39500 when the thickness is 50 μm and 43800 when the thickness is 60 μm. The product of the tensile elongation (%) and the thickness (μm) of ZK207 in the vertical direction is 51000 when the thickness is 50 μm and 52200 when the thickness is 60 μm.

Subsequently, the puncture strength and the impact strength of the laminated body were measured in the same manner as in the case of Example 1. As a result, the piercing strength was 13.4N and the impact strength was 623 kJ / m.

Subsequently, in the same manner as in the case of Example 1, a bag 10 was produced using the laminated body 30, and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was set to S size as in the case of Example 1. As a result, it was confirmed that in 10 of the 10 bags 10, no damage such as holes in the laminated body 30 or wrinkles formed in the laminated body 30 occurred.

(Comparative Example 1)
Two stretched plastic films and a sealant layer were laminated by a dry laminating method to prepare a laminated body. As the two stretched plastic films, a stretched PET film having a thickness of 12 μm was used as in the case of Example 1. As the film for forming the sealant layer, an unstretched polypropylene film ZK500 manufactured by Toray Film Processing Co., Ltd. was used as in the case of Example 1. The thickness of the sealant layer was 60 μm. As the two adhesives for laminating the two stretched plastic films and the sealant layer, as in the case of Example 1, a two-component polyurethane adhesive manufactured by Rock Paint Co., Ltd. (main agent: RU-40, Hardener: H-4) was used. The thickness of the adhesive layer made of the adhesive was 3.5 μm. The layer structure of the laminated body in Comparative Example 1 can be expressed as follows in order from the outer surface side to the inner surface side.
Stretched plastic film / adhesive layer / stretched plastic film / adhesive layer / sealant layer In addition, "/" represents the boundary between layers.

Subsequently, the puncture strength and the impact strength of the laminated body were measured in the same manner as in the case of Example 1. As a result, the piercing strength was 13.7N and the impact strength was 1109kJ / m.

Subsequently, in the same manner as in the case of Example 1, a bag 10 was produced using the laminated body 30, and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was set to S size as in the case of Example 1. As a result, it was confirmed that the laminated body 30 had holes in 3 of the 10 bags 10.

(Comparative Example 2)
A bag 10 was prepared using the same laminate 30 as in Comparative Example 1, and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was M size as in the case of Example 2. As a result, it was confirmed that one of the ten bags 10 had a hole in the laminated body 30.

The layer structure and the evaluation result of the laminated body of Examples 1 to 3 and Comparative Examples 1 and 2 are summarized in FIG. In FIG. 9, in the column of "layer structure", the components of the laminated body are described from the top in order from the layer on the outer surface side. As can be seen from the comparison between Examples 1 to 3 and Comparative Examples 1 and 2, the heat resistance of the laminate 30 can be enhanced by including the three stretched plastic films laminated by the dry laminate. rice field. As can be seen from the comparison between Comparative Example 1 and Comparative Example 2, the heat resistance of the laminated body 30 became better as the size of the bag 10 was larger.

10 Bag 11 Upper 12 Lower 12a Lower seal 13 Side 13a Side seal 14 Front film 15 Back film 16 Lower film 17 Storage 18 Contents 20 Steam vent mechanism 20a Steam vent seal 30 Laminated body 40 First stretched plastic Film 45 1st adhesive layer 50 2nd stretched plastic film 55 2nd adhesive layer 60 3rd stretched plastic film 65 3rd adhesive layer 70 Sealant layer

Claims (7)

It ’s a laminated body,
A first stretched plastic film, a second stretched plastic film, a third stretched plastic film and a sealant layer are provided in this order at least.
The first stretched plastic film, the second stretched plastic film, and the third stretched plastic film all contain polyester as a main component.
The sealant layer is an unstretched film containing a first thermoplastic resin and a second thermoplastic resin.
The first thermoplastic resin is made of a propylene / ethylene block copolymer.
The second thermoplastic resin contains at least an α-olefin copolymer or polyethylene and contains at least.
A laminate in which the mass ratio of the first thermoplastic resin is higher than the mass ratio of the second thermoplastic resin. A first adhesive layer located between the first stretched plastic film and the second stretched plastic film, and a second adhesive layer located between the second stretched plastic film and the third stretched plastic film. The laminate according to claim 1, further comprising a third adhesive layer located between the third stretched plastic film and the sealant layer. The second aspect of claim 2, wherein the first adhesive layer, the second adhesive layer, and the third adhesive layer all contain a cured product of a polyol and an isocyanate compound and have a thickness of 2 μm or more. Laminate. The laminate according to any one of claims 1 to 3, wherein the thickness of the first stretched plastic film, the second stretched plastic film, and the third stretched plastic film is 9 μm or more and 25 μm or less. The laminate according to any one of claims 1 to 4, which is for a microwave oven. It ’s a bag,
The invention according to any one of claims 1 to 5, wherein at least the first stretched plastic film, the second stretched plastic film, the third stretched plastic film, and the sealant layer are provided in this order from the outer surface side to the inner surface side. Laminated body and
A bag comprising a sealing portion for joining the inner surfaces of the laminated body to each other. The bag according to claim 6, comprising a steam venting mechanism.

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