JP2020026127A - Laminate and bag constructed therefrom - Google Patents

Abstract

To provide a laminate that has an impact resistance.SOLUTION: The laminate includes at least a first stretched plastic film 40, a second stretched plastic film 50 and a sealant film 70 in this order. The first stretched plastic film 40 and the second stretched plastic film 50 contain polyester as a main component. The product of the tensile elongation (%) of the sealant film 70 in the flow direction and the thickness (μm) of the sealant film 70 is 45000 or more.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a laminate and a bag formed from the laminate.

  2. Description of the Related Art In the past, many cooked or semi-cooked liquids, viscous substances, or contents in which a liquid and a solid are mixed and filled and sealed in a bag made of a plastic laminate have been on the market. In the bag, the non-seal part where the laminates are not joined together constitutes a storage part in which the contents are stored. In addition, a seal portion in which the laminates are joined seals the housing portion. The contents are, for example, cooked foods such as curries, stews, and soups. The contents are heated by a microwave oven or the like while being stored in the bag.

  By the way, when the content stored in the sealed bag is heated using a microwave oven, the water contained in the content evaporates with the heating, and the pressure in the storage unit increases. When the pressure in the bag housing increases, the bag may burst and the contents may scatter, thereby contaminating the inside of the microwave oven. In consideration of such problems, for example, Patent Literature 1 proposes to provide a mechanism for automatically communicating the storage unit and the outside when the pressure of the storage unit is increased to release the steam in the storage unit to the outside. ing. In addition, in Patent Document 1, in order to provide the bag with resistance to heating, as a laminate constituting the bag, a stretched polyethylene terephthalate film, a silica-deposited stretched polyethylene terephthalate film, an alumina-deposited stretched polyethylene terephthalate film, a stretched nylon film, a stretched nylon film, It has been proposed to use a polypropylene film, a polypropylene / ethylene-vinyl alcohol copolymer co-extrusion co-stretched film, or a composite film obtained by laminating two or more of these films.

JP 2015-120550 A

  The inventors of the present invention have conducted intensive studies and found that sufficient impact resistance may not be achieved depending on the laminate constituting a conventional bag.

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

  The present invention is a laminate, comprising at least a first stretched plastic film, a second stretched plastic film, and a sealant film in this order, and one of the first stretched plastic film or the second stretched plastic film is made of polyester. The sealant film contains polypropylene as the main component, the sealant film contains polypropylene, and the product of the tensile elongation (%) of the sealant film in the flow direction and the thickness (μm) of the sealant film is: The laminate is 45,000 or more.

  In the laminate according to the present invention, a product of a tensile modulus (MPa) of the sealant film in a flow direction and a thickness (μm) of the sealant film may be 38000 or less.

  In the laminate according to the present invention, the impact strength of the laminate may be 1050 kJ / m or more.

  In the laminate according to the present invention, the piercing strength of the laminate may be 14 N or more.

  In the laminate according to the present invention, the sealant film may include a propylene / ethylene block copolymer, which is a main component, and an α-olefin copolymer.

  The laminate according to the present invention includes a first adhesive layer located between the first stretched plastic film and the second stretched plastic film, and a first adhesive layer located between the second stretched plastic film and the sealant film. 2 adhesive layer, wherein the first adhesive layer and the second adhesive layer each include a cured product of a polyol and an isocyanate compound, and have a thickness of 2 μm or more. Good.

  The present invention is a bag, comprising: a laminated body including an outer surface and an inner surface; and a seal portion for joining inner surfaces of the laminated body to each other, wherein the laminated body is a first stretched plastic film, a second stretched plastic film. And at least a sealant film in this order, one of the first stretched plastic film or the second stretched plastic film includes polyester as a main component, the sealant film includes polypropylene, and the sealant film in a flow direction. A bag wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film is 45,000 or more.

  According to the present invention, a laminate having impact resistance can be provided.

It is a front view showing a bag in an embodiment of the invention. FIG. 3 is a cross-sectional view illustrating a case where the bag illustrated in FIG. 1 is viewed along a line III-III. It is sectional drawing which shows an example of the layer structure of the laminated body which comprises a bag. It is sectional drawing which shows an example of the layer structure of a 2nd stretched plastic film. It is sectional drawing which shows an example of a mode that heat is transmitted to the outer surface side from the inner surface side of a laminated body. It is a figure which shows an example of the measuring method of piercing strength. It is a top view which shows the test piece for evaluating impact strength. It is sectional drawing of the test piece shown in FIG. It is a figure showing an example of a measuring method of impact strength. FIG. 4 is a diagram showing evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2.

  An embodiment of the present invention will be described with reference to FIGS. In the drawings attached to the present specification, the scale, the vertical and horizontal dimensional ratios, and the like are appropriately changed from those of the actual product and exaggerated for convenience of illustration and understanding.

  In addition, in this specification, to specify the shape and geometric conditions and the degree thereof, for example, such as "parallel", "orthogonal", "identical" and the like, and the value of the length and angle, etc., strict Without being constrained by the meaning, it should be interpreted to include a range in which a similar function can be expected.

  FIG. 1 is a front view showing a bag 10 according to the present embodiment. The bag 10 includes a storage unit 17 that stores 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 whose 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 stored in the bag 10 to the outside. The steam release mechanism 20 allows the inside and the outside of the bag 10 to communicate with each other to release the steam when the pressure of the steam becomes equal to or higher than a predetermined value, and suppresses the escape of the steam from a portion other than the steam release mechanism 20. ,It is configured. Hereinafter, the configuration of the bag 10 will be described.

In the present embodiment, the bag 10 is a gusset-type bag configured to be self-supporting. The bag 10 includes an upper part 11, a lower part 12, and a side part 13, and has a substantially rectangular outline in a front view. Note that names such as “upper”, “lower” and “side”, and terms such as “upper” and “lower” refer to a state in which the bag 10 It is merely a relative representation of the position and orientation of 10 and its components. The posture at the time of transporting or using the bag 10 is not limited by the names and terms in this specification.

  As shown in FIG. 1, the bag 10 includes a front film 14 forming a front surface, a back film 15 forming a back surface, and a lower film 16 forming a lower portion 12. The lower film 16 is disposed between the front film 14 and the back film 15 in a state where the lower film 16 is folded at the folding portion 16f.

  In addition, the above-mentioned terms "front film", "back film", and "lower film" are only those in which each film is partitioned according to the positional relationship, and the method of providing the film when manufacturing the bag 10, It is not limited by the above terms. For example, the bag 10 may be manufactured using one film in which the front film 14, the back film 15, and the lower film 16 are continuously provided, and one sheet in which the front film 14 and the lower film 16 are continuously provided. It may be manufactured using a total of two films, one film and one back film 15, and a total of three films, one front film 14, one back film 15, and one lower film 16. It may be manufactured using.

  The inner surfaces of the front film 14, the back film 15, and the lower film 16 are joined to each other by a seal portion. In the plan view of the bag 10 such as FIG. 1, hatching is applied to the seal portion.

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

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

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

Venting mechanism following describes the structure of venting mechanism 20. FIG. 2 is a cross-sectional view showing a case where the steam release mechanism 20 of the bag 10 shown in FIG. 1 is viewed along the line II-II.

  The steam release seal portion 20a of the steam release mechanism 20 has a shape that is easily peeled off with an increase in the pressure of the housing portion 17. For example, the steam release seal portion 20a has a shape protruding from the side seal portion 13a toward the inside of the bag 10. Thereby, the force applied to the steam release seal portion 20a when the pressure of the storage portion 17 increases can be made larger than the force applied to the side seal portion 13a. Further, the width of the steam release seal portion 20a is smaller than the width of the side seal portion 13a. As shown in FIGS. 1 and 2, a non-seal portion 20 b is formed between the steam release seal portion 20 a and the outer edge of the side portion 13. Thereby, the communication between the housing portion 17 and the outside due to the peeling of the seal portion can be more easily generated in the steam release seal portion 20a than in the side seal portion 13a. The configuration and arrangement of the steam venting mechanism 20 are limited to those shown in FIGS. 1 and 2 as long as the housing 17 can be communicated with the outside of the bag 10 when the pressure of the housing 17 increases. There is no.

Layer Configuration of Front Film and Back Film Next, the layer configuration of the front film 14 and the back film 15 will be described. FIG. 3 is a cross-sectional view illustrating an example of a layer configuration of the laminate 30 that forms the front film 14 and the back film 15.

  As shown in FIG. 3, the laminate 30 includes at least a first stretched plastic film 40, a first adhesive layer 45, a second stretched plastic film 50, a second adhesive layer 55, and a sealant film 70 in this order. The first stretched plastic film 40 is located on the outer surface 30y side, and the sealant film 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 accommodation unit 17 side.

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

(First 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 layer for giving the laminate 30 a predetermined strength. The first stretched plastic film 40 may be a uniaxially stretched film stretched in one predetermined direction or a biaxially stretched film stretched in two predetermined directions. 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 a direction in which the side portion 13 extends, or may be stretched in a direction orthogonal to the direction in which the side portion 13 extends. The stretching 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. As the polyester, at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid, and at least one selected from ethylene glycol, 1,3-propanediol and 1,4-butanediol A polyester mainly composed of an aromatic polyester composed of one kind of aliphatic alcohol is preferred. Examples of polyester include polyethylene terephthalate (hereinafter also referred to as PET), polybutylene terephthalate (hereinafter also referred to as PBT), and the like. In addition, 51% by mass or more of the polyester in the first stretched plastic film 40 may be composed of one type of polyester, or may be composed of two or more types of polyester.

  The thickness of the first stretched plastic film 40 is preferably 9 μm or more, more preferably 12 μm or more. Further, the thickness of the first stretched plastic film 40 is preferably 25 μm or less, and more preferably 20 μm or less. By setting the thickness of the first stretched plastic film 40 to 9 μm or more, the first stretched plastic film 40 has sufficient strength. By setting the thickness of the first stretched plastic film 40 to 25 μm or less, the first stretched plastic film 40 exhibits excellent moldability. For this reason, the process of manufacturing the bag 10 by processing the laminate 30 can be efficiently performed.

  The purpose of the present embodiment is to provide a laminate 30 having heat resistance. As one of the methods for improving the heat resistance of the laminate 30, it is conceivable to configure each layer of the laminate 30 using a material having a thermal conductivity equal to or higher than a predetermined value. For example, the thermal conductivity of the material forming the first stretched plastic film 40 is preferably 0.05 W / m · K or more, and more preferably 0.10 W / m · K or more. The thermal conductivity of PET is, for example, 0.14 W / m · K. 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 more, holes are formed in the first stretched plastic film 40 when the contents contained in the bag 10 manufactured using the laminate 30 are heated. That is, the formation of wrinkles on the first stretched plastic film 40 can be suppressed.

  Preferably, the first stretched plastic film contains polyester as a main component and has a loop stiffness of 0.0017 N / 15 mm or more in the machine direction (MD) and the vertical direction (TD). The loop stiffness is a parameter indicating the strength of the film. Hereinafter, a method for measuring loop stiffness will be described.

First, a test piece is prepared by cutting a stretched plastic film into strips having a long side and a short side. Subsequently, both ends of the strip in the long side direction are fixed in a state where the strip test piece is curved to form a circular loop having a predetermined diameter. Thereafter, the circular loop is pushed in over a predetermined distance from the outside. Then, the load required for pushing is recorded as loop stiffness.
In the present embodiment, the length of the short side of the strip is 15 mm, and the length of the long side is 150 mm. The diameter of the circular loop was 60 mm, and the pushing distance of the circular loop was 40 mm. The above-mentioned loop stiffness of “0.0017 N / 15 mm” means that the load required to press a circular loop of a rectangular test piece having a short side of 15 mm into a length of 40 mm is 0.17 N. When measuring the loop stiffness in the flow direction, a test piece is prepared so that the flow direction of the stretched plastic film matches the long side direction of the strip.
When measuring the loop stiffness in the vertical direction, a test piece is prepared such that the vertical direction of the stretched plastic film matches the long side direction of the strip. As a loop stiffness measuring device, for example, LOOP STIFFNESS TESTER manufactured by Toyo Seiki Co., Ltd. can be used.

  By using a stretched plastic film having a loop stiffness of 0.0017 N / 15 mm or more in the machine direction (MD) and the vertical direction (TD) as the first stretched plastic film 40, the piercing strength of the first stretched plastic film 40 is increased. Can be. Thereby, in the laminate 30 of FIG. 3 including the first stretched plastic film 40 and the second stretched plastic film 50, the piercing strength of the laminate 30 can be, for example, 13 N or more, and more preferably 14 N or more. And more preferably at least 15N or at least 16N.

In the following description, a stretched plastic film that has a stretched plastic film having a loop stiffness of 0.0017 N / 15 mm or more in the machine direction (MD) and the vertical direction (TD) and that includes polyester as a main component will be referred to as a high Also called a stiffness polyester film. Examples of the high stiffness polyester film include a high stiffness PET film containing 51% by mass or more of PET, a high stiffness PBT film containing 51% by mass or more of PBT, and the like. The thickness of the high stiffness polyester film is preferably 5 μm or more, more preferably 7 μm or more.
Further, the thickness of the high stiffness polyester film is preferably 25 μm or less, more preferably 20 μm or less.

Preferred mechanical properties of the high stiffness polyester film will be further described.
The piercing strength of the high stiffness polyester film is preferably 10 N or more, more preferably 11 N or more.
The tensile strength of the high stiffness polyester film in the flow direction is preferably at least 250 MPa, more preferably at least 280 MPa. The tensile strength of the high stiffness polyester film in the vertical direction is preferably at least 250 MPa, more preferably at least 280 MPa.
The tensile elongation of the high stiffness polyester film in the machine direction is preferably 130% or less, more preferably 120% or less. The tensile elongation of the high stiffness polyester film in the vertical direction is preferably 120% or less, more preferably 110% or less.
Preferably, the value obtained by dividing the tensile strength of the high stiffness polyester film by the tensile elongation in at least one direction is 2.0 [MPa /%] or more. For example, the value obtained by dividing the tensile strength of the high stiffness polyester film in the vertical direction (TD) by the tensile elongation is preferably 2.0 [MPa /%] or more, and more preferably 2.2 [MPa /%]. That is all. The value obtained by dividing the tensile strength of the high stiffness polyester film in the machine direction (MD) by the tensile elongation is preferably 1.8 [MPa /%] or more, more preferably 2.0 [MPa /%] or more. is there.
The tensile strength and the tensile elongation can be measured according to JIS K7127. As a measuring device, a tensile tester STA-1150 manufactured by Orientec can be used. As the test piece, a high stiffness polyester film cut into a rectangular film having a width of 15 mm and a length of 150 mm can be used. The interval at the start of the measurement between the pair of chucks holding the test piece is 100 mm, and the tensile speed is 300 mm / min. The environmental temperature during the test is 25 ° C.
In the bag 10 shown in FIG. 1, the first direction D1 corresponds to a flow direction (MD) of the first stretched plastic film 40 and a second stretched plastic film 50 described later. The second direction D2 corresponds to a vertical direction (TD) of the first stretched plastic film 40 and a second stretched plastic film 50 described later.

The heat shrinkage of the high stiffness polyester film in the flow direction is preferably 0.7% or less, more preferably 0.5% or less. The heat shrinkage of the high stiffness polyester film in the vertical direction is preferably 0.7% or less, more preferably 0.5% or less. The heating temperature when measuring the heat shrinkage is 100 ° C., and the heating time is 40 minutes.
The Young's modulus of the high stiffness polyester film in the flow direction is preferably at least 4.0 GPa, more preferably at least 4.5 MPa. The Young's modulus of the high stiffness polyester film in the vertical direction is preferably 4.0 GPa or more, and more preferably 4.5 GPa or more.

  In the production process of the high stiffness polyester film, for example, first, the plastic film obtained by melting and molding the polyester is 3 to 4.5 times at 90 ° C. to 145 ° C. in the flow direction and the vertical direction, respectively. A first stretching step of stretching the film is performed. Subsequently, a second stretching step is performed in which the plastic film is stretched 1.1 to 3.0 times at 100 ° C. to 145 ° C. in the flow direction and the vertical direction, respectively. Thereafter, heat setting is performed at a temperature of 190 ° C to 220 ° C. Subsequently, in the flow direction and the vertical direction, a relaxation treatment (a treatment for reducing the film width) of about 0.2% to 2.5% is performed at a temperature of 100 ° C to 190 ° C. In these steps, a high stiffness polyester film having the above-mentioned mechanical properties can be obtained by adjusting the stretching ratio, stretching temperature, heat setting temperature, and relaxation rate.

(First adhesive layer)
The first adhesive layer 45 includes an adhesive for bonding the first stretched plastic film 40 and the second stretched plastic film 50 by a dry lamination method. The adhesive constituting the first adhesive layer 45 is generated from an adhesive composition prepared by mixing a first composition containing a main agent and a solvent, and a second composition containing a curing agent and a solvent. Specifically, the adhesive includes a cured product generated by the reaction between the main agent and the solvent in the adhesive composition.

  Examples of the adhesive include polyurethane and the like. Polyurethane is a cured product generated by reacting a polyol as a main component with 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 generated by reacting a polyether polyol as a main component with an isocyanate compound as a curing agent. Polyester polyurethane is a cured product generated by the reaction between a polyester polyol as a main component 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). Or an adduct or multimer of the above-mentioned various isocyanate compounds.

  The material forming the first adhesive layer 45 preferably has a higher thermal conductivity than the material forming the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70. For example, the thermal conductivity of the material forming the first adhesive layer 45 is preferably 1.0 W / m · K or more, more preferably 3.0 W / m · K or more. The thermal conductivity of the 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 manufactured using the laminate 30 is heated, the heat generated in the housing portion 17 causes the inner surface 30x of the laminate 30 to be heated. While being transmitted from the side to the outer surface 30y side, heat is easily diffused in the surface direction of the laminate 30. Thereby, the heat dissipation of the stacked body 30 can be improved, and thus the temperature rise of the stacked body 30 can be suppressed. This can prevent the laminate 30 from being damaged by heat when the bag 10 is heated. That is, the heat resistance of the laminate 30 can be increased.

  The thickness of the first adhesive layer 45 is preferably 2 μm or more, and more preferably 3 μm or more. Further, the thickness of the first adhesive layer 45 is preferably 6 μm or less, and more preferably 5 μm or less. By setting the thickness of the first adhesive layer 45 to 3 μm or more, diffusion of heat in the surface direction of the laminate 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, like the first stretched plastic film 40. Similarly to the first stretched plastic film 40, the second stretched plastic film 50 also functions as a base layer for giving the laminate 30 a predetermined strength. The stretching direction of the second stretched plastic film 50 is not particularly limited as in the case of the first stretched plastic film 40.

  The second stretched plastic film 50 contains polyamide as a main component. For example, the second stretched plastic film 50 contains 51% by mass or more of polyamide. Examples of the polyamide system include an aliphatic polyamide or an aromatic polyamide. Examples of the aliphatic polyamide include nylons such as nylon-6, nylon-6,6, and a copolymer of nylon-6 and nylon-6,6. As the aromatic polyamide, polymethaxylene adipamide ( MXD6). When the second stretched plastic film 50 contains polyamide as a main component, the piercing strength of the laminate 30 including the second stretched plastic film 50 can be increased.

  When the second stretched plastic film 50 contains polyamide as a main component, the thickness of the second stretched plastic film 50 is preferably 12 μm or more, more preferably 15 μm or more. When the second stretched plastic film 50 contains polyamide as a main component, the thickness of the second stretched plastic film 50 is preferably 25 μm or less, more preferably 20 μm or less. When the second stretched plastic film 50 contains polyamide as a main component, the thermal conductivity of the second stretched plastic film 50 is preferably 0.25 W / m · K or more, more preferably 0.3 W / m. -It is K or more. The thermal conductivity of nylon is, for example, 0.35 W / m · K. When the second stretched plastic film 50 contains polyamide as a main component, the stretch ratio of the second stretched plastic film 50 is, for example, 1.05 times or more.

  The second stretched plastic film 50 may be constituted by a single layer, or may be constituted by a plurality of layers. When the second stretched plastic film 50 includes a plurality of layers, the second stretched plastic film 50 is, for example, a co-extrusion film manufactured by co-extrusion. The second stretched plastic film 50 produced by co-extrusion includes, for example, as shown in FIG. 4, a first layer 51 made of polyester such as PET, a second layer 52 made of polyamide such as nylon, and A third layer 53 made of polyester such as PET is included. When the mass of the second layer 52 made of polyamide such as nylon is 51% or more of the total mass of the second stretched plastic film 50, the main component of the second stretched plastic film 50 produced by co-extrusion is polyamide. It can be said that

(Second adhesive layer)
The second adhesive layer 55 includes an adhesive for bonding the second stretched plastic film 50 and the sealant film 70 by a dry lamination method. As an example of the adhesive of the second adhesive layer 55, polyurethane can be used as in the case of the first adhesive layer 45. In addition to the configuration, material, and characteristics described below, the same configuration, material, and characteristics of the second adhesive layer 55 as those of the first adhesive layer 45 can be employed.

  Like the first adhesive layer 45, the material forming the second adhesive layer 55 preferably has a higher heat than the material forming the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70. Has conductivity. For example, the thermal conductivity of the material forming 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. Further, the thickness of the second adhesive layer 55 is preferably 6 μm or less, more preferably 5 μm or less.

  By the way, as described above, an aromatic isocyanate compound and an aliphatic isocyanate compound exist as the isocyanate compound constituting the curing agent of the adhesive. Among these, in the aromatic isocyanate compound, components that cannot be used for food use elute under a high temperature environment such as heat sterilization. Incidentally, the second adhesive layer 55 is in contact with the sealant film 70. For this reason, when the second adhesive layer 55 contains an aromatic isocyanate compound, the components eluted from the aromatic isocyanate compound adhere to the contents contained in the container 17 in contact with the sealant film 70. There is.

  In consideration of such a problem, preferably, as an adhesive constituting the second adhesive layer 55, a cured product generated by a reaction between a polyol as a main component and an aliphatic isocyanate compound as a curing agent Is used. Accordingly, it is possible to prevent components that cannot be used for food use due to the second adhesive layer 55 from adhering to the contents.

(Relational expression)
Next, a relational expression established between the stretched plastic films 40 and 50 and the adhesive layers 45 and 55 will be described. In the stacked body 30, preferably, the following relational expression is satisfied.
A1 + A2 <B1 + B2
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.
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.

  The above relational expression means that the adhesive layers 45 and 55 have higher thermal conductivity in the plane direction of the laminate 30 than the stretched plastic films 40 and 50. Thereby, when heating the content accommodated in the bag 10, it is possible to suppress the laminate 30 from being damaged by the influence of heat. Examples of damage caused to the laminate 30 by the influence of heat include a hole in the laminate 30 and a wrinkle formed in the laminate 30.

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

  FIG. 5 is a view showing a state in which the contents 18 are attached to the inner surface 30x of the laminated body 30 constituting the bag 10. The attachment of the contents 18 to the inner surface 30x occurs, for example, when heating the contents 18 contained in the bag 10 using a microwave oven, a part of the contents 18 jumps and reaches the inner surface 30x. obtain. When the content 18 attached to the inner surface 30x is further heated, the temperature of the laminate 30 in contact with the content 18 also increases, and a hole is formed in the laminate 30 or wrinkles are formed in the laminate 30. Can be considered.

  Here, in the present embodiment, the stacked body 30 is configured so that the above relational expression is satisfied. The laminate 30 includes two or more stretched plastic films 40 and 50 and adhesive layers 45 and 55. For this reason, as shown in FIG. 5, while the heat generated in the contents 18 is transmitted from the inner surface 30x side to the outer surface 30y side of the laminate 30, the heat is particularly transmitted to the laminate 30 in the adhesive layers 45 and 55. In the direction of the surface. As a result, heat is easily released to the outside of the bag 10, so that a temperature rise in a portion of the laminate 30 to which the contents 18 are attached can be suppressed. Thus, the laminate 30 can be prevented from being damaged by heat. That is, the heat resistance of the laminate 30 can be increased.

  B1 + B2 is preferably at least 3.5 times, more preferably at least 4.0 times, even more preferably at least 4.5 times A1 + A2.

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

  The bag 10 composed of the laminate 30 is subjected to a sterilization treatment such as a boil treatment or a retort treatment at a high temperature. Therefore, the sealant film 70 having heat resistance to withstand these high-temperature treatments is used.

  The melting point of the material constituting the sealant film 70 is preferably 150 ° C. or higher, and more preferably 160 ° C. or higher. By increasing the melting point of the sealant film 70, the retort treatment of the bag 10 can be performed at a high temperature, so that the time required for the retort treatment can be shortened. Note that the melting point of the material forming the sealant film 70 is lower than the melting point of the resin forming the stretched plastic films 40 and 50.

  When considered from the viewpoint of the retort treatment, a material containing propylene as a main component can be used as a material constituting the sealant film 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 propylene / ethylene block copolymer, propylene / ethylene random copolymer, polypropylene such as homopolypropylene, or a mixture of polypropylene and polyethylene. Can be. Here, “propylene / ethylene block copolymer” means a material having a structural formula represented by the following formula (I). The “propylene / ethylene random copolymer” means a material having a structural formula represented by the following formula (II). “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 mainly containing propylene, 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 where polypropylene is continuous.

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

  Preferably, the sealant film 70 is a single-layer film including a propylene / ethylene block copolymer. For example, the sealant film 70 is a single-layer unstretched film mainly composed of a propylene / ethylene block copolymer. By using the propylene / ethylene block copolymer, the impact resistance of the sealant film 70 can be increased, and thereby, it is possible to suppress the bag 10 from being broken due to the impact at the time of falling. Further, the stab resistance of the laminate 30 can be improved.

  Further, by using the propylene / ethylene block copolymer, the strength of the seal portion formed of the sealant film 70 at a high temperature, for example, at 100 ° C. or more (hereinafter, also referred to as a hot seal strength) can be reduced at a low temperature For example, the sealing strength is extremely small at room temperature. For example, the hot seal strength at 100 ° C. becomes one-fourth or less of the seal strength at 25 ° C. (hereinafter, also referred to as room temperature seal strength). For example, the hot seal strength at a width of 15 mm at 100 ° C. is 20 N or less, preferably 15 N or less, more preferably 10 N or less. The room-temperature sealing strength at a width of 15 mm at 100 ° C. is 40 N or more, preferably 50 N or more, and more preferably 60 N or more. Since the hot seal strength is low, when the bag 10 is heated using a microwave oven, the steam release seal portion 20a is easily peeled off, and the steam in the storage portion 17 is easily released to the outside of the bag 10. For this reason, it is possible to suppress the internal pressure of the storage section 17 from becoming excessive, thereby suppressing the occurrence of damage to the stacked body 30 during heating. The seal strength can be measured according to JIS Z1707 7.5. As a measuring device, for example, a tensile tester with a thermostat RTC-1310A manufactured by Orientec can be used.

  The propylene / ethylene block copolymer includes, for example, a sea component composed of polypropylene and an island component composed of an ethylene / propylene copolymer rubber component. The sea component can contribute to enhancing the blocking resistance, heat resistance, rigidity, seal 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 including 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 composed of polypropylene is at least 51% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more.

  The single-layer sealant film 70 may further include 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 an α-olefin copolymer and polyethylene. The α-olefin copolymer is, for example, a 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, density of 0.910 g / cm ³ or more and 0.925 g / cm ³ or less of polyethylene. The medium density polyethylene is a 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 a polyethylene having a density of 0.941 g / cm ³ or more and 0.965 g / cm ³ or less. Low-density polyethylene is 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 are obtained, for example, by polymerizing ethylene at a medium or low pressure of 1 atm or more and less than 1000 atm.

The medium density polyethylene and the high density polyethylene may partially include a copolymer of ethylene and an α-olefin. Further, even when ethylene is polymerized at a medium pressure or a low pressure, when a copolymer of ethylene and an α-olefin is contained, a medium- or low-density polyethylene can be produced. 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 a medium pressure or a low pressure to introduce short-chain branches. Examples of the α-olefin 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.

  Note that 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).

Each of R ₁ and R ₂ is H (hydrogen atom) or an alkyl group such as CH ₃ and C ₂ H ₅ . Also, j and k are each an integer of 1 or more. J is larger than k. That is, in the α-olefin copolymer represented by the formula (IV), the structure on the left side including R ₁ 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 composed of the propylene / ethylene block copolymer is at least 51% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more.

  As described above, the second thermoplastic resin can contribute to increasing 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.

  In addition, the sealant film 70 may further include a thermoplastic elastomer. By using a thermoplastic elastomer, the impact resistance and piercing resistance of the sealant film 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 comprising at least one polymer block A mainly composed of a vinyl aromatic compound and at least one polymer block B mainly composed of a 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, and is a random copolymer of 50 to 90% by mass of ethylene as a main component and α-olefin as a comonomer. is there.

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

  Examples of the method for producing the propylene / ethylene block copolymer include a method in which a raw material such as propylene or ethylene is polymerized using a catalyst. As the catalyst, a Ziegler-Natta type, metallocene catalyst or the like can be used.

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

The mechanical properties of the sealant film 70 will be described.
The tensile elongation at 25 ° C. of the sealant film 70 in the machine direction (MD) is preferably 800% or more, more preferably 900% or more, and may be 1000% or more, or 1100% or more. Further, the product of the tensile elongation (%) of the sealant film 70 and the thickness (μm) of the sealant film 70 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 60000 or more. The tensile elongation at 25 ° C. of the sealant film 70 in the vertical direction (TD) is preferably 1050% or more, and more preferably 1100% or less. The product of the tensile elongation (%) of the sealant film 70 and the thickness (μm) of the sealant film 70 in the vertical direction (TD) is preferably 53,000 or more, more preferably 60,000 or more. Since the sealant film 70 has a high tensile elongation, it is possible to prevent the bag 10 from being broken due to an impact when dropped.

Further, the tensile modulus at 25 ° C. of the sealant film 70 in the flow direction (MD) is preferably 670 MPa or less, more preferably 650 MPa or less. Further, the product of the tensile modulus (MPa) of the sealant film 70 in the flow direction (MD) and the thickness (μm) of the sealant film 70 is preferably 38,000 or less, more preferably 35,000 or less. Further, the tensile modulus at 25 ° C. of the sealant film 70 in the vertical direction (TD) is preferably 550 MPa or less, more preferably 500 MPa or less. The product of the tensile modulus (MPa) of the sealant film 70 and the thickness (μm) of the sealant film 70 in the vertical direction (TD) is preferably 30,000 or less, more preferably 25,000 or less.
In the bag 10 shown in FIG. 1, the first direction D1 corresponds to the flow direction (MD) of the sealant film 70. Further, the second direction D2 corresponds to the vertical direction (TD) of the sealant film 70.

  The tensile modulus and tensile elongation can be measured according to JIS K7127. As a measuring device, a tensile tester STA-1150 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 70, and the direction in which the side portions 13 extend is the sealant film 70. Such as 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 portions 13 extend is the film flow direction.

(Other layers)
The laminate 30 may further include a layer not shown in FIG. Hereinafter, examples of further layers will be described.

  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 to the bag 10 or to impart aesthetics, and is printed on the first stretched plastic film 40, for example. The printing layer expresses 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. Specific examples of the gravure printing ink include Finart manufactured by DIC Graphics Co., Ltd.

  Further, the laminate 30 may further include a transparent gas barrier layer. The transparent gas barrier layer is formed on the surfaces of the stretched plastic films 40 and 50, and includes at least a transparent vapor deposition layer made of a transparent inorganic material. Further, the transparent gas barrier layer may be formed on the surface of the transparent vapor deposition layer, and may further include a transparent gas barrier coating film having transparency.

  The transparent vapor-deposited layer functions as a layer having a gas barrier function of preventing permeation of oxygen gas, water vapor, and the like. Note that two or more transparent evaporation layers may be provided. When there are two or more transparent vapor-deposited layers, each may have the same composition or different compositions. Examples of the method for forming the transparent vapor-deposited layer include a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, and an ion plating method; a plasma chemical vapor deposition method; Chemical vapor deposition (Chemical Vapor Deposition, CVD) such as chemical vapor deposition and photochemical vapor deposition. Specifically, a deposition layer can be formed on a deposition roller using a roller deposition film deposition apparatus. Examples of the inorganic material constituting the transparent vapor deposition layer include aluminum oxide (aluminum oxide), silicon oxide, and the like. The thickness of the transparent vapor-deposited layer is preferably 40 ° or more and 130 ° or less, more preferably 50 ° or more and 120 ° or less.

The transparent gas barrier coating film is a layer that functions as a layer that suppresses transmission of oxygen gas, water vapor, and the like. The transparent gas barrier coating film 37 has a general formula R ¹ _nM (OR ² ) _m (where R ¹ and R ² each represent an organic group 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 valency of M.) and at least one alkoxide represented by the above-mentioned polyvinyl alcohol- A transparent gas barrier composition containing a sol-based resin and / or an ethylene-vinyl alcohol copolymer, and further polycondensed by a sol-gel method in the presence of a sol-gel method catalyst, an acid, water, and an organic solvent. can get.

Next, the layer configuration 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 joined to the inner surface of the front film 14 and the inner surface of the back film 15. For example, similarly to the front film 14 and the back film 15, the above-described laminate 30 may be used as the lower film 16. Alternatively, a film having an inner surface made of a sealant film and having a configuration different from that of the laminate 30 may be used as the lower film 16.

Method for producing a laminate Next, an example of a method for producing a laminate 30.

  First, the above-described first stretched plastic film 40 and second stretched plastic film 50 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 a dry lamination method. Thereafter, a laminate including the first stretched plastic film 40 and the second stretched plastic film 50 and the sealant film 70 are laminated via the second adhesive layer 55 by a dry lamination method. Thereby, the laminate 30 including the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70 can be obtained.

  Alternatively, first, the second stretched plastic film 50 and the sealant film 70 are laminated by a dry lamination method via the second adhesive layer 55, and then, the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film The laminated body 30 may be manufactured by laminating the laminated body including the layer 70 through the first adhesive layer 45 by a dry lamination method.

In the dry lamination method, first, an adhesive composition is applied to one of two films to be laminated. Subsequently, the applied adhesive composition is dried to evaporate the solvent.
Thereafter, the two films are laminated via the dried adhesive composition. Subsequently, aging is performed for at least 24 hours in an environment of, for example, 20 ° C. or more while the two laminated films are wound up.

Method for producing a bag Next, a method for producing the bag 10 with the laminate 30 described above. First, the front film 14 and the back film 15 made of the laminate 30 are prepared. In addition, the folded lower film 16 is inserted between the front film 14 and the back film 15. Subsequently, the inner surfaces of the respective films are heat-sealed to form seal portions such as a lower seal portion 12a and a side seal portion 13a. In addition, 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 into the bag 10 through the opening 11b of the upper part 11. The contents 18 are, for example, cooked foods containing moisture, such as curries, stews, and soups. Further, the contents 18 may include a material containing a large amount of oil, such as meat, fish, and a seasoning therefor. In addition to food, what can be heated by hot water etc. can be stored in the bag 10 as contents. Then, the upper part 11 is heat-sealed to form an upper seal part. Thus, the sealed bag 10 in which the contents 18 are stored can be obtained.

Heating method of the contents Next, an example of a method for heating the contents 18 contained in the bag 10.

  First, the bag 10 is placed inside the microwave oven in a state where the bag 10 is made to stand by itself with the lower part 12 down. Next, the contents are heated using a microwave oven. As a result, the temperature of the contents 18 increases, and accordingly, the moisture contained in the contents 18 evaporates, and the pressure of the storage unit 17 increases.

  When the pressure in the housing 17 increases, the front film 14 and the back film 15 expand outward due to the force received from the housing 17. Here, in the present embodiment, the laminate 30 constituting the front film 14 and the back film 15 includes two stretched plastic films 40 and 50. For this reason, the rigidity of the laminate 30 is increased, and as a result, when the front film 14 and the back film 15 are subjected to a force, the front film 14 and the back film 15 can be suppressed from being stretched. Thereby, the force generated due to the pressure generated in the housing portion 17 can be mainly used as the force for peeling off the steam release seal portion 20a, not the force for stretching the front film 14 and the back film 15. it can. For this reason, the force applied to the steam release seal portion 20a can be increased. This makes it easy for the steam release seal portion 20a to peel off during heating, and allows the steam in the storage portion 17 to escape to the outside via the steam release mechanism 20.

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

  According to the present embodiment, as described above, the product of the tensile elongation (%) and the thickness (μm) in the flow direction (MD) of the sealant film 70 of the laminate 30 is 45000 or more, and The product of the tensile elongation (%) and the thickness (μm) in the direction is 53000 or more. Thereby, the impact strength of the laminate 30 can be increased. Thereby, the impact resistance of the bag 10 constituted by the laminate 30 can be enhanced. For example, it is possible to prevent the bag 10 from being broken by an impact at the time of falling. The impact strength of the laminate 30 is preferably at least 1050 kJ / m, more preferably at least 1100 kJ / m, even more preferably at least 1200 kJ / m.

  According to the present embodiment, as described above, the laminate 30 includes at least two stretched plastic films 40 and 50. For this reason, the laminated body 30 and the bag 10 constituted by the laminated body 30 can have piercing resistance. The piercing strength of the laminate 30 is preferably 13 N or more, more preferably 14 N or more, and even more preferably 15 N or more.

  Note that various changes can be made to the above-described embodiment. Hereinafter, modified examples will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, portions that can be configured in the same manner as in the above-described embodiment will use the same reference numerals as those used for corresponding portions in the above-described embodiment, A duplicate description will be omitted. Further, when it is clear that the operation and effect obtained in the above-described embodiment can be obtained also in the modification, the description thereof may be omitted.

(Modification of layer structure)
In the above-described embodiment, an example has been described in which the first stretched plastic film 40 contains polyester as a main component and the second stretched plastic film 50 contains polyamide as a main component. However, the present invention is not limited thereto, and the first stretched plastic film 40 may include polyamide as a main component, and the second stretched plastic film 50 may include polyester as a main component. That is, it is only necessary that one of the first stretched plastic film 40 and the second stretched plastic film 50 contains polyester as a main component and the other contains polyamide as a main component. When one of the first stretched plastic film 40 and the second stretched plastic film 50 contains polyamide as a main component, the laminate 30 can have piercing resistance. When the first stretched plastic film 40 contains polyamide as a main component, the first stretched plastic film 40 is made of a polyester such as PET laminated in order as in the example of the second stretched plastic film 50 shown in FIG. It is preferable to include a first layer 51 made of, a second layer 52 made of polyamide such as nylon, and a third layer 53 made of polyester such as PET.

(Modification of bag)
In the above-described embodiment, an example in which the bag 10 is a gusset-type bag has been described, 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 film 14 and the back film 15 made of the laminated body 30 at the upper part 11, the lower part 12, and the side part 13.

  Further, in the above-described embodiment, an example has been described in which the content 18 contained in the bag 10 is heated using a microwave oven, but the present invention is not limited to this. For example, the contents 18 contained in the bag 10 may be heated by hot water decoction. In this case, the bag 10 does not need to include the above-described steam vent mechanism 20.

  Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist.

(Example 1)
As the first stretched plastic film 40, a stretched PET film having a thickness of 12 μm was prepared. In addition, as the second stretched plastic film 50, a stretched plastic film containing polyamide as a main component and having a thickness of 15 μm was prepared. Further, as the sealant film 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 film 70 was 60 μm.

  ZK500 has a higher tensile elongation than a general unstretched polypropylene film. Specifically, the tensile elongation of ZK500 in the machine direction (MD) is 1180% when the thickness is 50 μm and 1100% when the thickness is 60 μm. The tensile elongation of the 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 62,000 when the thickness is 50 μm and 69000 when the thickness is 60 μm.

  Further, ZK500 has a lower tensile modulus than a general unstretched polypropylene film. Specifically, the tensile modulus of the ZK500 in the machine direction (MD) is 640 MPa when the thickness is 50 μm, and 550 MPa when the thickness is 60 μm. The tensile 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 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 modulus (MPa) and the thickness (μm) of the ZK500 in the vertical direction is 24000 when the thickness is 50 μm and 35000 when the thickness is 60 μm.

Subsequently, the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70 were laminated by a dry lamination method to produce a laminate 30.
As the first adhesive layer 45 and the second adhesive layer 55, a two-pack polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. In addition, RU-40 of the main agent is a polyester polyol. The thickness of the first adhesive layer 45 and the second adhesive layer 55 was 3.5 μm.

[Evaluation of piercing resistance]
Subsequently, the piercing strength of the laminate 30 was measured in accordance with JIS Z1707 7.4. As a measuring instrument, Tensilon Universal Material Testing Machine RTC-1310 manufactured by A & D was used.
Specifically, as shown in FIG. 6, a semi-circular needle 90 having a diameter of 1.0 mm and a tip shape radius of 0.5 mm is placed on the test piece of the fixed laminate 30 from the outer surface 30y side, as shown in FIG. 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 the stress was measured for five or more test pieces, and the average value was defined as the piercing strength of the laminate 30. The environment during the measurement was a temperature of 23 ° C. and a relative humidity of 50%. As a result, the piercing strength was 15.2N.

[Evaluation of impact resistance]
Subsequently, the two laminates 30 were stacked and heated at 190 ° C. for 1 second, and the inner surfaces 30x of the laminate 30 were heat-sealed to each other. Next, the two heat-sealed laminates 30 were cut out at a width of 15 mm to produce test pieces 100. FIG. 7 is a plan view showing the test piece 100, and FIG. 8 is a cross-sectional view of the test piece 100 in FIG. The test piece 100 has a width W3 of 15 mm and a length W4 of 50 mm, 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. 9, the unsealed portion of one laminated body 30 and the unsealed portion of the other laminated body 30 are opposite to each other in a direction orthogonal to the surface direction of the sealing portion 101. , That is, after forming a T-shape, the end of the unsealed portion of one of the stacked bodies 30 and the end of the unsealed portion of the other stacked body 30 are respectively jigs 102 , 103. At this time, the distance T between the jigs 102 and 103 in a direction orthogonal to the surface direction of the seal portion 101 was set to 40 mm. Subsequently, when one of the jigs 102 is hit with a hammer 104 from the surface of the one of the laminates 30 on the side of the first stretched plastic film 40, the one of the laminates 30 and the other of the laminates 30 are separated from each other. Was measured for impact strength. The measurement was performed using a digital impact tester manufactured by Toyo Seiki Seisaku-sho, Ltd. As a hammer for applying an impact to the test piece 100, a 2J hammer was used. As a result, the impact strength was 1207 kJ / m.

[Evaluation of heat resistance]
Subsequently, a bag 10 was prepared using the laminate 30 and the heat resistance of the bag 10 was evaluated. Specifically, first, the bag 10 shown in FIG. The height S1 of the bag 10 was 145 mm and the width S2 was 140 mm. The height S3 of the folded lower film 16, that is, the height from the lower end 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-sized bag 10. Subsequently, the contents of 100 g containing a large amount of oil were filled into the inside of the bag 10 and the upper portion 11 was heat-sealed to form an upper seal portion.

  Thereafter, the bag 10 containing the contents was heated using a microwave oven with a power of 500 W for 2 minutes, 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 one of the bags 10 did not suffer damage such as a hole in the laminate 30 or wrinkles formed in the laminate 30.

  In addition, instead of the content of 100 g containing a large amount of oil, an S-size bag 10 containing a hamburger is prepared, and the bag 10 containing the content is used for 2 minutes using a microwave oven of 500 W output. Was heated to check whether or not the laminate 30 constituting the bag 10 was damaged. As a result, in nine out of ten bags 10, it was confirmed that no damage such as a hole in the laminate 30 or wrinkles was formed in the laminate 30.

(Example 2)
A bag 10 was produced using the same laminate 30 as in 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 a content containing a large amount of oil was filled into the inside of the bag 10, and the upper portion 11 was heat-sealed to form an upper seal portion.

  Thereafter, as in the case of the first embodiment, the bag 10 containing the contents is heated for 2 minutes using a microwave oven having an output of 500 W, and whether the laminated body 30 constituting the bag 10 is damaged or not. I checked. As a result, it was confirmed that in the two bags 10 out of ten, no damage such as formation of a hole in the laminate 30 and formation of wrinkles in the laminate 30 occurred.

  Also, instead of the content of 100 g containing a lot of oil, an M-size bag 10 containing a hamburger is prepared, and the content of the bag 10 is stored for 2 minutes using a microwave oven of 500 W output. Was heated to check whether or not the laminate 30 constituting the bag 10 was damaged. As a result, in ten out of ten bags 10, it was confirmed that no damage such as a hole in the laminate 30 or a wrinkle was formed in the laminate 30.

(Comparative Example 1)
The first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70 were laminated by a dry lamination method to produce a laminate. As the first stretched plastic film 40, a stretched PET film having a thickness of 12 μm was used as in the case of Example 1. As the second stretched plastic film 50, a stretched plastic film containing polyamide as a main component and having a thickness of 15 μm was used as in the case of Example 1. As the sealant film 70, an unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used. The thickness of the sealant film 70 was 70 μm. As the adhesive of the two adhesive layers for laminating the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70, as in the case of Example 1, a two-part liquid manufactured by Rock Paint Co., Ltd. A polyurethane adhesive (main agent: RU-40, curing agent: H-4) was used. The thickness of the adhesive layer made of the adhesive was 3.5 μm. The layer configuration of the laminate in Comparative Example 1 can be expressed as follows from the outer surface side to the inner surface side.
First stretched plastic film / adhesive layer / second stretched plastic film / adhesive layer / sealant film In addition, "/" represents a boundary between layers.

  ZK207 has a lower tensile elongation than ZK500. Specifically, the tensile elongation of ZK207 in the machine direction (MD) is 790% when the thickness is 50 μm, and 730% when the thickness is 60 μm. Further, 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.

  Further, ZK207 has a higher tensile modulus than ZK500. Specifically, the tensile modulus of the ZK207 in the machine direction (MD) is 780 MPa when the thickness is 50 μm, and 680 MPa when the thickness is 60 μm. The tensile modulus of the 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 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 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.

  Subsequently, the piercing strength and the impact strength of the laminate 30 were measured in the same manner as in Example 1. As a result, the piercing strength was 15 N, and the impact strength was 989 kJ / m.

  Subsequently, in the same manner as in Example 1, a bag 10 was produced using the laminate 30 and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was S size as in the case of the first embodiment. As a result, holes were confirmed in the laminate 30 in 10 out of 10 bags 10.

  In addition, instead of the content of 100 g containing a large amount of oil, an S-size bag 10 containing a hamburger is prepared, and the bag 10 containing the content is used for 2 minutes using a microwave oven of 500 W output. Was heated to check whether or not the laminate 30 constituting the bag 10 was damaged. As a result, no holes were found in the laminate 30 in four out of ten bags, but holes were found in the laminate 30 in six out of ten bags.

(Comparative Example 2)
A laminate 30 was produced in the same manner as in Comparative Example 1, except that an unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. having a thickness of 70 μm was used as the sealant film 70.

  Subsequently, the piercing strength and the impact strength of the laminate 30 were measured in the same manner as in Example 1. As a result, the piercing strength was 16N and the impact strength was 1028 kJ / m.

Subsequently, in the same manner as in Example 1, a bag 10 was produced using the laminate 30 and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was M size as in the case of the second embodiment. As a result, holes were confirmed in the laminate 30 in 10 out of 10 bags 10.
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 the second embodiment. As a result, no holes were found in the laminate 30 in six out of ten bags, but holes were found in the laminate 30 in four out of ten bags.

  In addition, instead of the content of 100 g containing a large amount of oil, an S-size bag 10 containing a hamburger is prepared, and the bag 10 containing the content is used for 2 minutes using a microwave oven of 500 W output. Was heated to check whether or not the laminate 30 constituting the bag 10 was damaged. As a result, no holes were found in the laminate 30 in six out of ten bags, but holes were found in the laminate 30 in four out of ten bags.

  FIG. 10 shows the layer configurations and evaluation results of the laminates of Examples 1 and 2 and Comparative Examples 1 and 2. In FIG. 10, in the column of “Layer Configuration”, the constituent elements of the laminate are described from the top in order from the outer layer. Further, in the column of "heat resistance evaluation 1", the evaluation result when 100 g of a content containing a large amount of oil was filled in the bag 10 is described. In the column of "heat resistance evaluation 2", a hamburger is used. The evaluation result in the case of being stored inside the bag 10 is described.

  As can be seen from the comparison between Example 1 and Comparative Examples 1 and 2, in the laminate 30 including the first stretched plastic film 40 containing polyester as the main component and the second stretched plastic film 50 containing polyamide as the main component, the sealant film By using an unstretched polypropylene film ZK500 containing a propylene / ethylene block copolymer as No. 70, the impact resistance and heat resistance of the laminate 30 could be improved.

  In addition, as can be seen from the comparison between Example 1 and Example 2, the heat resistance of the laminate 30 was improved as the size of the bag 10 was increased.

DESCRIPTION OF SYMBOLS 10 Bag 11 Upper part 12 Lower part 12a Lower seal part 13 Side part 13a Side seal part 14 Surface film 15 Back film 16 Lower film 17 Housing part 18 Contents 20 Vapor release mechanism 20a Vapor release seal part 30 Stack 40 First stretched plastic Film 45 First adhesive layer 50 Second stretched plastic film 55 Second adhesive layer 70 Sealant film

Claims (7)

A laminate,
At least a first stretched plastic film, a second stretched plastic film and a sealant film are provided in this order,
One of the first stretched plastic film or the second stretched plastic film includes polyester as a main component, and the other includes polyamide as a main component,
The sealant film includes polypropylene,
A laminate, wherein the product of the tensile elongation (%) of the sealant film in the flow direction and the thickness (μm) of the sealant film is 45,000 or more.   The laminate according to claim 1, wherein a product of a tensile modulus (MPa) of the sealant film in a flow direction and a thickness (μm) of the sealant film is 38000 or less.   The laminate according to claim 1 or 2, wherein the impact strength of the laminate is 1050 kJ / m or more.   The laminate according to any one of claims 1 to 3, wherein the piercing strength of the laminate is 14N or more.   The laminate according to any one of claims 1 to 4, wherein the sealant film includes a propylene / ethylene block copolymer as a main component and an α-olefin copolymer. 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 sealant film. In addition,
6. The method according to claim 1, wherein each of the first adhesive layer and the second adhesive layer includes a cured product of a polyol and an isocyanate compound, and has a thickness of 2 μm or more. 7. Laminate. A bag,
A laminate including an outer surface and an inner surface,
A seal portion that joins the inner surfaces of the laminate,
The laminate includes at least a first stretched plastic film, a second stretched plastic film, and a sealant film in this order,
One of the first stretched plastic film or the second stretched plastic film includes polyester as a main component, and the other includes polyamide as a main component,
The sealant film includes polypropylene,
A bag wherein the product of the tensile elongation (%) of the sealant film in the flow direction and the thickness (μm) of the sealant film is 45,000 or more.