Sealant film, laminate, and pouch

Abstract

To provide: a sealant film that does not stretch excessively compared to other layers when a pouch is heated by a microwave oven or the like, thereby preventing the progression of peeling of a sealing portion of a steam vent mechanism; a laminate; and a pouch.SOLUTION: The sealant film used in a laminate constituting a microwave-safe pouch includes a matrix resin component composed of block polypropylene and a dispersed component containing at least polyethylene. In the flow direction of the sealant film, a dimensional change rate at temperatures ranging from 20°C to 125°C measured in a tensile mode using TMA is 5.0% or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sealant film, a laminate, and a pouch. [Background technology]

[0002] Conventionally, many pouches made of plastic laminates are available on the market, filled and sealed with cooked or semi-cooked liquid, viscous material, or a mixture of liquid and solid. In the pouch, the unsealed portion where the laminates are not joined constitutes the storage portion in which the contents are stored. Also, the sealed portion where the laminates are joined seals the storage portion. The contents are, for example, cooked foods such as curry, stew, soup, etc. The contents are heated in a microwave oven or the like while contained in the pouch.

[0003] When the contents contained in a sealed pouch are heated in a microwave oven, the moisture contained in the contents evaporates as the contents are heated, and the pressure in the storage section increases. If the pressure in the storage section of the pouch increases, the pouch may burst, scattering the contents and soiling the inside of the microwave oven. In consideration of such a problem, for example, Patent Document 1 proposes providing the pouch with a steam release mechanism that automatically connects the storage section to the outside when the pressure in the storage section increases, and releases steam in the storage section to the outside. In Patent Document 1, the steam release mechanism has a sealed section located between the upper side seal section and the lower side seal section of the pouch, and an unsealed section that is isolated from the storage section by the sealed section and extends to reach the side edge of the pouch. If the pressure in the storage section increases, the sealed section of the steam release mechanism peels off, and the storage section and the unsealed section communicate with each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-101154 Summary of the Invention [Problem to be solved by the invention]

[0005] The sealant layer located on the inner surface of the laminate is made of a sealant film. The laminate includes a base material made of a stretched plastic film in addition to the sealant layer. The sealant layer is more stretchable than the base material.

[0006] When the pouch is heated in a microwave oven or the like, the sealant layer of the laminate located at the sealed portion of the steam release mechanism may stretch more than the other layers, which hinders the progress of peeling of the sealed portion of the steam release mechanism.

[0007] An object of the present invention is to provide a sealant film, a laminate, and a pouch that can solve these problems. [Means for solving the problem]

[0008] The embodiments of the present disclosure relate to the following [1] to

[12] . [1] A sealant film for use in a laminate constituting a microwave pouch, comprising: A matrix resin component made of block polypropylene and a dispersion component containing at least polyethylene, A sealant film, wherein the dimensional change rate of the sealant film in the machine direction from 25°C to 125°C in a tensile mode using TMA is 5.0% or less.

[0009] [2] The sealant film according to [1] may have a composite elastic modulus of 800 MPa or less.

[0010] [3] The sealant film according to [1] or [2] may have a thickness of 40 μm or more and 60 μm or less.

[0011] [4] The sealant film described in [3] may have a thickness of 40 μm or more and 50 μm or less.

[0012] [5] The sealant film according to any one of [1] to [4] may consist of a single layer.

[0013] [6] A laminate for forming a microwave pouch, comprising: A sealant layer comprising the sealant film according to any one of [1] to [5]; a first substrate located outside the sealant layer in a thickness direction of the laminate, the first substrate including a biaxially oriented plastic film.

[0014] [7] The laminate according to [6] may further include a second substrate located between the first substrate and the sealant layer in the thickness direction and including a biaxially oriented plastic film.

[0015] [8] In the laminate according to [7], the first substrate may contain polyester, and the second substrate may contain polyester or polyamide.

[0016] [9] A microwave pouch comprising: A front surface film and a back surface film each having a laminate according to any one of [6] to [8]; a seal portion that joins the sealant layer of the front surface film and the sealant layer of the back surface film; and a steam venting mechanism.

[0017]

[10] In the pouch described in [9], the sealed portion may include an outer edge sealed portion located on the outer edge of the pouch, and the steam vent mechanism may include an isolating seal portion extending from the outer edge sealed portion toward the containing portion, and an unsealed portion isolated from the containing portion by the isolating seal portion.

[0018]

[11] In the pouch described in

[10] , the seal strength in the machine direction of the outer edge seal portion at 100°C may be 6.0 N or more and 12.0 N or less.

[0019]

[12] In the pouch described in

[11] , the ratio of the seal strength in the vertical direction of the outer edge seal portion at 100°C to the seal strength in the machine direction of the outer edge seal portion at 100°C may be 1.8 or more. Effect of the Invention

[0020] According to the present invention, the sealed portion of the steam release mechanism can be appropriately peeled off. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a front view showing a pouch according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded view showing a laminate constituting a pouch according to one embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate. [Figure 4] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate. [Diagram 5] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate. [Figure 6] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate. [Figure 7] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate. [Figure 8] FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate. [Figure 9] 1 is a graph showing an example of the results of a thermomechanical analysis of a sealant film. [Figure 10] FIG. 2 is a front view of a sealed pouch. [Figure 11] FIG. 4 is a diagram for explaining a method for measuring seal strength. [Figure 12] FIG. 4 is a diagram for explaining a method for measuring seal strength. [Figure 13] FIG. 4 is a diagram for explaining a method for measuring seal strength. [Figure 14] 11A and 11B are diagrams illustrating the manner in which an isolation seal portion of a steam release mechanism peels off in an embodiment. [Figure 15]13 is a diagram showing the state in which an isolation seal portion of a steam vent mechanism peels off in a comparative embodiment. FIG. [Figure 16] FIG. 13 is a front view showing a modified example of the pouch. [Figure 17] FIG. 13 is a front view showing a modified example of the pouch. [Figure 18] 1 is a table showing examples of components of a sealant film. [Figure 19] 1 is a table showing the evaluation results in Examples 1 to 3 and Comparative Examples 1 to 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the present disclosure is not limited to the embodiments and examples described below. Note that the drawings shown below are schematic. Therefore, the size and shape of each part are appropriately exaggerated to make it easier to understand.

[0023] The numerical values ​​such as dimensions of each member and the names of materials described in this specification are examples of embodiments, and are not limited to these, and may be appropriately selected and used. In this specification, terms specifying shapes and geometric conditions, such as parallel, orthogonal, and perpendicular, are intended to include substantially the same state in addition to their strict meanings.

[0024] In this specification, when two or more upper limit candidates and two or more lower limit candidates are given for a certain parameter, the numerical range of the parameter may be constructed by combining any one of the upper limit candidates and any one of the lower limit candidates. For example, consider a case where "parameter B may be, for example, A1 or more and may be A2 or more. Parameter B may be, for example, A3 or less and may be A4 or less." In this case, the numerical range of parameter B may be A1 or more and A3 or less, A1 or more and A4 or less, A2 or more and A3 or less, or A2 or more and A4 or less.

[0025] <Pouch composition> FIG. 1 is a front view showing a pouch 10 according to an embodiment of the present disclosure. The pouch 10 includes an upper edge 14, a lower edge 13 opposite the upper edge 14, a first side edge 11 extending between the upper edge 14 and the lower edge 13, and a second side edge 12. The lower edge 13 and the upper edge 14 face each other in a first direction D1. The first side edge 11 and the second side edge 12 face each other in a second direction D2. The first direction D1 and the second direction D2 may be perpendicular to each other. In this specification, the upper edge 14 side may be referred to as the upper side and the lower edge 13 as the lower side along the first direction D1.

[0026] In this embodiment, the pouch 10 is a standing pouch having a rectangular shape in a front view and a bottom gusset. The names "upper edge", "lower edge", and "side edge", as well as the terms "upper side" and "lower side", merely indicate the relative positions and directions of the pouch 10 and its components based on a state in which the pouch 10 stands on its own with the bottom gusset at the bottom. The position of the pouch 10 during transportation or use is not limited by the names and terms in this specification. In this disclosure, a rectangle is a concept that includes not only a rectangle with four right-angled corners, but also a rectangle with four chamfered corners that are convex outwardly in a circular arc shape.

[0027] 1, the upper edge 14 of the pouch 10 is not sealed, and the pouch 10 is not filled with any contents. The pouch 10 in the present disclosure is not limited to the pouch 10 in an unfilled state, but also includes the pouch 10 in an filled state.

[0028] <Pouch structure> FIG. 2 is an exploded view showing the films constituting the pouch 10 according to an embodiment of the present disclosure. As shown in FIG. 2, the pouch 10 of the embodiment is composed of three films: a substantially rectangular front (front) film 1, a back film 2 having the same shape as the front film 1, and a substantially rectangular bottom film 3. The pouch 10 of the present embodiment is formed by heat-sealing the inner surfaces of the three films, the front film 1, the back film 2, and the bottom film 3, at predetermined locations. As shown in FIG. 2, the bottom film 3 is folded in half and divided into a first portion 3f and a second portion 3g with the folded portion 3a as the boundary. The bottom film 3 is provided with four semicircular arc-shaped second cutout portions 3b, 3c, 3d, and 3e that cut out the side edges, and the second cutout portions 3b and 3c and the second cutout portions 3d and 3e are provided at positions that correspond to when the film is folded in half. A second bottom seal portion 7b, which will be described later, is formed via the second cutout portions 3b to 3e.

[0029] From the viewpoint of stabilizing the self-supporting property when cooking using a microwave oven, it is preferable that the distance L3 from the folded-in portion 3a to the lower edge 13 of the pouch 10 in the direction perpendicular to the folded-in portion 3a is equal to or greater than a predetermined value. The distance L3 is, for example, equal to or greater than 35 mm, and may be equal to or greater than 40 mm. The distance L3 is, for example, equal to or less than 60 mm, and may be equal to or less than 50 mm.

[0030] <Components of the pouch> The pouch 10 includes a storage section 71, a sealed section, and a steam release mechanism 20. The storage section 71 is a space in which the contents are stored. An unsealed section surrounded by the sealed section constitutes the storage section 71. The unsealed section includes a front film 1 and a back film 2 whose inner surfaces are not joined to each other.

[0031] <Sealing section> The seal portion is a portion that joins the inner surfaces of two films together. As described below, the inner surface of each film is formed of a sealant layer. Therefore, the seal portion joins the sealant layers of the two films together.

[0032] The seal includes a perimeter seal located at the outer edge of the pouch 10. As shown in Figure 1, the perimeter seal includes a first side seal 5, a second side seal 6, and a bottom seal 7. The seal also includes an isolation seal 20b. In the example shown in Figure 1, the isolation seal 20b is connected to the first side seal 5. An opening 15 is formed in the top edge 14.

[0033] The first side seal portion 5, the second side seal portion 6, and the isolating seal portion 20b are formed by joining the inner surface of the front film 1 and the inner surface of the back film 2 by thermal welding. The first side seal portion 5 is located at the first side edge 11. The second side seal portion 6 is located at the second side edge 12. An unsealed portion constituting the storage portion 71 is defined between the first side seal portion 5 and the second side seal portion 6. In the example shown in FIG. 1, the unsealed portion surrounded by the first side seal portion 5, the second side seal portion 6, the bottom seal portion 7, and the isolating seal portion 20b constitutes the storage portion 71.

[0034] The isolating seal portion 20b isolates the unsealed portion 20a from the storage portion 71. The unsealed portion 20a and the isolating seal portion 20b constitute the steam release mechanism 20.

[0035] The pouch 10 may include an unsealed portion 30a adjacent the second side edge 12. The unsealed portion 30a is separated from the containing portion 71 by the second side seal 6. The unsealed portion 30a may face the unsealed portion 20a in the second direction D2. The unsealed portion 30a may be in the same position as the unsealed portion 20a in the first direction D1.

[0036] A single pouch 10 may be obtained by forming sealed portions and unsealed portions of a plurality of pouches 10 along the length direction of the long front surface film 1 and back surface film 2, and cutting the films 1 and 2. In this case, the unsealed portion 20a and the unsealed portion 30a may be formed by cutting one unsealed portion. This allows the unsealed portion 20a to be reliably formed and reduces the amount of waste when manufacturing the pouch 10.

[0037] The first side seal 5 may include a lower portion 5a and an upper portion 5b. The lower portion 5a extends along the first side edge 11 from the unsealed portion 20a toward the bottom edge 13. The upper portion 5b extends along the first side edge 11 from the unsealed portion 20a toward the top edge 14.

[0038] The second side seal 6 may include a lower portion 6a and an upper portion 6b. The lower portion 6a extends along the second side edge 12 from the unsealed portion 30a toward the bottom edge 13. The upper portion 6b extends along the second side edge 12 from the unsealed portion 30a toward the top edge 14.

[0039] The widths W1, W4 of the lower portions 5a, 6a are, for example, 5 mm or more, and may be 6 mm or more. The widths W1, W4 of the lower portions 5a, 6a are, for example, 8 mm or less, and may be 7 mm or less. The widths W2, W5 of the upper portions 5b, 6b are, for example, 8 mm or more, and may be 10 mm or more. The widths W2, W5 of the upper portions 5b, 6b are, for example, 15 mm or less, and may be 13 mm or less. The widths W2, W5 of the upper portions 5b, 6b may be greater than the widths W1, W4 of the lower portions 5a, 6a. The width of the seal portion is the dimension of the seal portion in a direction perpendicular to the direction in which the seal portion extends.

[0040] The bottom seal portion 7 is a seal portion formed on the lower edge 13 side of the folded-in portion 3a. The bottom seal portion 7 may include a first bottom seal portion 7a and a second bottom seal portion 7b. The first bottom seal portion 7a includes a portion joining the inner surface of the surface film 1 to the inner surface of the first portion 3f of the bottom film 3, and a portion joining the inner surface of the back film 2 to the inner surface of the second portion 3g of the bottom film 3. The second bottom seal portion 7b joins the inner surface of the surface film 1 to the inner surface of the back film 2 via the second cutout portions 3b, 3c, 3d, and 3e.

[0041] <Bottom gusset> A first portion 3f of the bottom film 3 and a portion of the surface film 1 overlapping the first portion 3f form a first pleat. A second portion 3g of the bottom film 3 and a portion of the surface film 1 overlapping the second portion 3g form a second pleat. The first pleat and the second pleat form a bottom gusset 9. The front view of FIG. 1 shows the first pleat, which is located closer to the lower edge 13 than the fold-in portion 3a. The pouch 10 is provided with the bottom gusset 9, so that the pouch 10 can stand on its own.

[0042] <Containment Unit> After the contents are accommodated through opening 15, top seal portion 4 is formed along top edge 14, and pouch 10 is sealed, as shown in Fig. 10 described below. Top seal portion 4 is formed continuously from first side seal portion 5 to second side seal portion 6. Container portion 71 is defined by the inner edge of first side seal portion 5, the inner edge of second side seal portion 6, the inner edge of first bottom seal portion 7a, the inner edge of top seal portion 4, and the inner edge of isolation seal portion 20b.

[0043] <Method of opening> As shown in FIG. 2, the pouch 10 may include an opening means 5c located in the first side seal portion 5. The opening means 5c penetrates the front film 1 and the back film 2. The opening means 5c may be a notch, a cut, or the like. The opening means 5c can be a starting point when a user tears the pouch 10. The opening means 5c extends from the first side edge 11 toward the containing portion 71. The opening means 5c may be located between the unsealed portion 20a and the upper edge 14 in the first direction D1. That is, the opening means 5c may be formed in the upper portion 5b.

[0044] As shown in FIG. 2, the pouch 10 may include an opening means 6c located in the second side seal portion 6. The opening means 6c penetrates the front film 1 and the back film 2. The opening means 6c may be a notch, a cut, or the like. Like the opening means 5c, the opening means 6c can be a starting point for a user to tear the pouch 10. The opening means 6c extends from the second side edge 12 toward the containing portion 71. The opening means 6c may be formed in a portion of the second side seal portion 6 facing the opening means 5c in the second direction D2.

[0045] Although not shown, the pouch 10 may have an easy-open line formed on the front film 1 or the back film 2. The easy-open line includes a plurality of processed parts aligned along the second direction D2. The processed parts are structures formed on the laminate 40 by partially processing at least one layer of the laminate 40. For example, the processed parts include holes formed on at least one layer of the laminate 40. The holes may penetrate one layer of the laminate 40, or may not penetrate one layer of the laminate 40. The easy-open line may extend in the second direction D2 from the first side edge 11 to the second side edge 12. The easy-open line may be connected to the opening means 5c or the opening means 6c.

[0046] <Contents> The contents include moisture and oil. Examples of the contents are retort foods, frozen foods, refrigerated foods, etc. Examples of foods are curry, porridge, yakisoba, side dishes, fish, etc. When the pouch 10 is heated by a microwave oven or the like, the moisture in the contents evaporates as the pouch 10 is heated, increasing the pressure in the storage section 71 of the pouch 10. For this reason, a steam vent function is required to release steam from within the storage section 71 to the outside.

[0047] <Film details> The laminate 40 is a laminate made of a plurality of layers stacked together. The laminate 40 constituting the pouch 10 according to this embodiment includes at least a substrate and a sealant layer. The substrate may include a biaxially oriented plastic film. The sealant layer includes a sealant film. The sealant layer may be composed only of a sealant film. The sealant layer constitutes the inner surface of the laminate 40.

[0048] The front film 1 and the back film 2 are composed of a laminate 40. The bottom film 3 may also be composed of a laminate 40.

[0049] 3 is a cross-sectional view showing an example of a layer structure of the laminate 40. The laminate 40 may include, in order from the outer surface 401 side to the inner surface 402 side, a first substrate 41, a first adhesive layer 46, a second substrate 42, a second adhesive layer 47, and a sealant layer 44. The laminate 40 may include a printed layer 45 located between the first substrate 41 and the first adhesive layer 46. The first substrate 41 may form the outer surface 401 of the laminate 40. The sealant layer 44 forms the inner surface 402 of the laminate 40.

[0050] 4 and 5 are cross-sectional views showing an example of the layer structure of the laminate 40. In addition to the layers shown in FIG. 3, the laminate 40 may include a deposition layer 49a located on the surface of the first substrate 41 or the surface of the second substrate 42. In the example shown in FIG. 4, the deposition layer 49a is located on the inner surface of the first substrate 41. In the example shown in FIG. 5, the deposition layer 49a is located on the outer surface of the second substrate 42. The laminate 40 may include a coating layer 49b located on the surface of the deposition layer 49a.

[0051] 6 is a cross-sectional view showing an example of a layer structure of the laminate 40. The laminate 40 may include, in order from the outer surface 401 side to the inner surface 402 side, a first substrate 41, a first adhesive layer 46, a second substrate 42, a second adhesive layer 47, a third substrate 43, a third adhesive layer 48, and a sealant layer 44. The laminate 40 may include a printed layer 45 located between the first substrate 41 and the first adhesive layer 46. The first substrate 41 may form the outer surface 401 of the laminate 40. The sealant layer 44 forms the inner surface 402 of the laminate 40.

[0052] 7 and 8 are cross-sectional views showing an example of the layer structure of the laminate 40. In addition to the layers shown in FIG. 6, the laminate 40 may include a deposition layer 49a located on the surface of the first substrate 41, the surface of the second substrate 42, or the surface of the third substrate 43. In the example shown in FIG. 7, the deposition layer 49a is located on the inner surface of the first substrate 41. In the example shown in FIG. 8, the deposition layer 49a is located on the outer surface of the third substrate 43. The laminate 40 may include a coating layer 49b located on the surface of the deposition layer 49a.

[0053] Although not shown, the laminate 40 may include, in order from the outer surface side to the inner surface side, a first base material, a first adhesive layer, and a sealant layer. That is, the laminate 40 may include only one base material including a biaxially stretched plastic film. In other words, the laminate 40 may include only one biaxially stretched plastic film.

[0054] Each layer of the laminate 40 will now be described.

[0055] When the pouch 10 is heated in a microwave oven, the pouch 10 needs to be resistant to heat. It is preferable that the substrates such as the first substrate 41, the second substrate 42, and the third substrate 43 have heat resistance.

[0056] For example, the material of the substrate may be a polyester film such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), a polyamide film such as nylon, or a polypropylene film. The thickness of the first substrate 41 and the second substrate 42 is, for example, 10 μm or more, and may be 12 μm or more. The thickness of the substrate is, for example, 50 μm or less, and may be 40 μm or less, 25 μm or less, or 18 μm or less.

[0057] The substrate may be a biaxially stretched plastic film, which is a biaxially stretched plastic film. The material of the second substrate 42 may be the same as or different from the material of the first substrate 41. The thickness of the second substrate 42 may be the same as or different from the thickness of the first substrate 41. The material of the third substrate 43 may be the same as or different from the material of the first substrate 41. The thickness of the third substrate 43 may be the same as or different from the thickness of the first substrate 41.

[0058] The first base material 41 preferably includes a biaxially oriented plastic film containing a polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) as a main component. In one layer, the "main component" refers to the component having the largest content in that layer. The content of polyester in the first base material 41 is, for example, 80% by mass or more, and may be 90% by mass or more.

[0059] The second base material 42 preferably includes a biaxially oriented plastic film containing polyester or polyamide as a main component. The polyester is, for example, PET or PBT. The polyamide is, for example, nylon. The content of polyester or polyamide in the second base material 42 is, for example, 80% by mass or more, and may be 90% by mass or more.

[0060] The third base material 43 preferably includes a biaxially oriented plastic film containing polyester or polyamide as a main component. The polyester is, for example, PET or PBT. The polyamide is, for example, nylon. The content of polyester or polyamide in the third base material 43 is, for example, 80% by mass or more, and may be 90% by mass or more.

[0061] Table 1 shows examples of combinations of the first substrate 41, the second substrate 42, and the third substrate 43. Examples 1 and 2 are examples in which the laminate 40 contains one biaxially stretched plastic film. Examples 3 to 7 are examples in which the laminate 40 contains two biaxially stretched plastic films. Examples 8 to 12 are examples in which the laminate 40 contains three biaxially stretched plastic films. "PET" means a biaxially stretched plastic film containing PET as a main component. "Vapor-deposited PET" means a biaxially stretched plastic film containing PET as a main component and having a vapor-deposited layer 49a formed thereon. "ONY" means a biaxially stretched plastic film containing nylon as a main component. "Processed PET" means a biaxially stretched plastic film containing PET as a main component and having a processed portion with an easy-open line formed thereon. [Table 1]

[0062] The substrate may include a material derived from biomass. For example, the first substrate 41, the second substrate 42, and the third substrate 43 may include a polyester derived from biomass.

[0063] The first adhesive layer 46 contains an adhesive for bonding the first substrate 41 and the second substrate 42 together by a dry lamination method or the like. The second adhesive layer 47 contains an adhesive for bonding the second substrate 42 and the sealant layer 44 or the third substrate 43 together by a dry lamination method or the like. The third adhesive layer 48 contains an adhesive for bonding the third substrate 43 and the sealant layer 44 together by a dry lamination method or the like.

[0064] The adhesive may include a cured product produced by the reaction of the main agent and the curing agent. The cured product may be produced from an adhesive composition prepared by mixing a first composition containing the main agent and a solvent with a second composition containing the curing agent and a solvent. The cured product may be produced by reacting the main agent and the curing agent without using a solvent. In the following description, an adhesive including a cured product produced by reacting the main agent and the curing agent using a solvent is also referred to as a solvent-based adhesive. In the following description, an adhesive including a cured product obtained without using a solvent is also referred to as a solventless adhesive.

[0065] The first adhesive layer 46 may include a solvent-based adhesive or may include a solventless adhesive. The second adhesive layer 47 may include a solvent-based adhesive or may include a solventless adhesive. The third adhesive layer 48 may include a solvent-based adhesive or may include a solventless adhesive.

[0066] An example of the adhesive is polyurethane. Polyurethane is a cured product produced by reacting a polyol as a base agent with an isocyanate compound as a curing agent. Examples of polyurethane are polyether polyurethane, polyester polyurethane, etc. Polyether polyurethane is a cured product produced by reacting a polyether polyol as a base agent with an isocyanate compound as a curing agent. Polyester polyurethane is a cured product produced by reacting a polyester polyol as a base agent with an isocyanate compound as a curing agent.

[0067] Examples of the isocyanate compound include aromatic isocyanate compounds, aliphatic isocyanate compounds, and adducts or oligomers of isocyanate compounds. Examples of aromatic isocyanate compounds include tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), etc. Examples of aliphatic isocyanate compounds include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc.

[0068] The thickness of the adhesive layers such as the first adhesive layer 46, the second adhesive layer 47, and the third adhesive layer 48 is, for example, 0.5 μm or more, may be 1.0 μm or more, may be 1.5 μm or more, or may be 2.0 μm or more. The thickness of the adhesive layers is, for example, 5.0 μm or less, may be 4.0 μm or less, or may be 3.0 μm or less.

[0069] The material of the second adhesive layer 47 may be the same as or different from the material of the first adhesive layer 46. The thickness of the second adhesive layer 47 may be the same as or different from the thickness of the first adhesive layer 46. The material of the third adhesive layer 48 may be the same as or different from the material of the first adhesive layer 46. The thickness of the third adhesive layer 48 may be the same as or different from the thickness of the first adhesive layer 46.

[0070] The printed layer 45 is provided to display the product contents, to impart an aesthetic feel, to display the cut portion, etc. The printed layer 45 is formed from printing ink containing a binder and a pigment.

[0071] The deposition layer 49a is provided on the surface of the substrate to enhance the gas barrier property of the laminate 40. The deposition layer 49a may be transparent. The deposition layer 49a may be composed of a single deposition layer or may include two or more deposition layers. When the deposition layer 49a includes two or more deposition layers, each layer may have the same composition or different compositions. The deposition layer 49a may be formed by a physical vapor deposition method or a chemical vapor deposition method. Examples of the physical vapor deposition method include a vacuum deposition method, a sputtering method, and an ion plating method. Examples of the chemical vapor deposition method include a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, and a photochemical vapor deposition method. The deposition layer may be formed on the surface of the substrate on a film-forming roller using a roller-type deposition film-forming device.

[0072] The deposition layer 49a may be made of a transparent inorganic material. Examples of inorganic materials include metal oxides and inorganic oxides. Examples of metal oxides include oxides of metals such as aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), and yttrium (Y). Examples of inorganic oxides include oxides of silicon (Si). Aluminum oxide (aluminum oxide) and silicon oxide are preferred because they are transparent.

[0073] The thickness of the deposition layer 49a is, for example, 20 Å or more, and may be 30 Å or more, 40 Å or more, 50 Å or more, 60 Å or more, or 70 Å or more. The thickness of the deposition layer 49a is, for example, 150 Å or less, 130 Å or less, 120 Å or less, or 110 Å or less.

[0074] The coating layer 49b is provided on the surface of the deposition layer 49a in order to further enhance the gas barrier property of the laminate 40. The coating layer 49b may be transparent. The coating layer 49b is formed by applying a gas barrier composition containing at least one alkoxide and a polyvinyl alcohol resin and / or an ethylene-vinyl alcohol copolymer onto the deposition layer 49a. The gas barrier composition may be obtained by polycondensation by a sol-gel method in the presence of a sol-gel catalyst, an acid, water, a solvent, etc. The alkoxide is a compound represented by the general formula R 1 n M(OR 2 ) m (In the formula, R 1 , R 2 represents an organic group having 1 to 8 carbon atoms, 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 atomic valence of M.

[0075] The above general formula R 1 n M(OR 2 ) mAs the alkoxide represented by the formula (I), at least one of the following may be used: partial hydrolysis product of alkoxide, and condensation product of hydrolysis of alkoxide. In addition, the partial hydrolysis product of alkoxide does not need to have all alkoxy groups hydrolyzed, and may be one in which one or more alkoxy groups are hydrolyzed, or a mixture thereof. As the condensation product of hydrolysis of alkoxide, a dimer or more of the partially hydrolyzed alkoxide, specifically, a dimer to hexamer, is used.

[0076] The above general formula R 1 n M(OR 2 ) m In the alkoxide represented by the formula (I), examples of the metal atom represented by M include silicon, zirconium, titanium, aluminum, etc. Preferred metals include, for example, silicon and titanium. In the present embodiment, the alkoxide can be used alone or in the form of a mixture of two or more different metal atoms in the same solution.

[0077] The above general formula R 1 n M(OR 2 ) m In the alkoxide represented by the formula: 1 Examples of the organic group represented by the general formula R above include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-hexyl, and n-octyl. 1 n M(OR 2 ) m In the alkoxide represented by the formula: 2 Examples of the organic group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, etc. When two or more alkyl groups are contained in the same molecule, the two or more alkyl groups may be the same or different.

[0078] When preparing the transparent gas barrier composition, for example, a silane coupling agent may be added. An example of the silane coupling agent is an organoalkoxysilane containing an organic reactive group. In particular, an organoalkoxysilane having an epoxy group is preferably used. Specifically, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane is used. The silane coupling agent may be used alone or in combination of two or more kinds.

[0079] The thickness of the coating layer 49b is, for example, 100 nm or more, and may be 125 nm or more, 150 nm or more, or 200 nm or more. This allows stable gas barrier properties to be obtained. The thickness of the coating layer 49b is, for example, 500 nm or less, and may be 450 nm or less, 400 nm or less, or 300 nm or less.

[0080] Next, the sealant layer 44 will be described. The sealant layer 44 may be composed of one layer, or may include two or more layers. Preferably, the sealant layer 44 is composed of a single layer. The sealant layer 44 is preferably made of an unstretched film. The term "unstretched" refers not only to a film that is not stretched at all, but also to a film that is slightly stretched due to tension applied during film formation.

[0081] The pouch 10 formed from the laminate 40 is subjected to a sterilization treatment at high temperature, such as boiling or retort treatment. The sealant layer 44 preferably has heat resistance sufficient to withstand such high temperature treatments.

[0082] The melting point of the material constituting the sealant layer 44 is preferably 150° C. or higher, and more preferably 160° C. or higher. By increasing the melting point of the sealant layer 44, it becomes possible to perform the retort treatment of the pouch 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 44 is lower than the melting point of the resin constituting the base material.

[0083] The sealant layer 44 may include a material that includes propylene as a major component. For example, the sealant layer 44 may include polypropylene as a major component.

[0084] The sealant layer 44 may contain a matrix resin component and a dispersed component. For example, the sealant layer 44 may have a so-called sea-island structure in which the matrix resin component is a sea component and the dispersed component is an island component, with the island components dispersed in the sea component. The higher the content of the dispersed component, the higher the drop strength of the pouch 10 formed from the laminate 40. On the other hand, the higher the content of the dispersed component, the lower the hot seal strength, which will be described later.

[0085] The matrix resin component may be made of a block polypropylene, which is a copolymer containing at least a homopolypropylene and a block elastomer.

[0086] The block polypropylene may include a polymer part (a) made of a propylene polymer and a polymer part (b) made of polyethylene and an ethylene-propylene copolymer rubber component. The block polypropylene may include a sea part made of a propylene polymer and an island part made of polyethylene and an ethylene-propylene copolymer rubber component. The polymer part (a) and the sea part can contribute to improving the heat resistance, rigidity, blocking resistance and seal strength of the block polypropylene. The polymer part (b) and the island part can contribute to improving the impact resistance of the block polypropylene. Therefore, by adjusting the ratio of the polymer part (a) to the polymer part (b) and the ratio of the sea part to the island part, the mechanical properties of the sealant layer 44 containing the block polypropylene can be adjusted.

[0087] The propylene polymer of the polymer portion (a) is, for example, a propylene homopolymer having a melting point of 160° C. or higher. The propylene polymer may be a copolymer of propylene and a small amount (for example, 5 mol % or less) of an α-olefin, so long as the melting point is 160° C. or higher. Examples of the α-olefin include ethylene, 1-butene, 1-hexene, and 1-octene.

[0088] In the sealant layer 44, the content of the polymer portion (a) made of a propylene polymer or the sea component is preferably higher than the content of the polymer portion (b) made of polyethylene and an ethylene-propylene copolymer rubber component or the island component.

[0089] The content of the polymer part (a) made of a propylene polymer or the sea component in the sealant layer 44 is, for example, 30% by mass or more, may be 35% by mass or more, or may be 40% by mass or more. The content of the polymer part (a) made of a propylene polymer or the sea component in the sealant layer 44 is, for example, 55% by mass or less, may be 50% by mass or less, or may be 45% by mass or less.

[0090] The content of the polymer portion (b) made of polyethylene and ethylene-propylene copolymer rubber components or island components in the sealant layer 44 is, for example, 14 mass% or less, or may be 12 mass% or less, or may be 11 mass% or less. The content of the polymer portion (b) made of polyethylene and ethylene-propylene copolymer rubber components or island components in the sealant layer 44 is, for example, 7 mass% or more, or may be 8 mass% or more, or may be 9 mass% or more.

[0091] The content of the matrix resin component in the sealant layer 44 may be higher than the content of the dispersed component in the sealant layer 44. The content of the matrix resin component in the sealant layer 44 is, for example, 51 mass% or more, 55 mass% or more, or 60 mass% or more. The content of the matrix resin component in the sealant layer 44 is, for example, 70 mass% or less, 65 mass% or less, 60 mass% or less, or 55 mass% or less.

[0092] The dispersion component may include polyethylene, which may contribute to increasing the impact resistance of the sealant layer 44. Examples of polyethylene include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and the like.

[0093] The content of polyethylene in the dispersed component in the sealant layer 44 is, for example, 30% by mass or more, and may be 35% by mass or more. The content of polyethylene in the dispersed component in the sealant layer 44 is, for example, 50% by mass or less, and may be 45% by mass or less.

[0094] The dispersed component may contain an elastomer. The elastomer may contribute to increasing the impact resistance of the sealant layer 44. Examples of the elastomer include a propylene-ethylene random copolymer (propylene-ethylene elastomer) and an ethylene-α-olefin copolymer (ethylene-α-olefin elastomer). Preferably, the dispersed component contains an elastomer made of a propylene-ethylene random copolymer. By using a propylene-ethylene random copolymer as the dispersed component, the drop strength of the pouch 10 can be improved while suppressing a decrease in the hot seal strength of the laminate 40.

[0095] The content of the propylene-ethylene random copolymer in the dispersed component in the sealant layer 44 is, for example, 5% by mass or more, optionally 7% by mass or more, or 9% by mass or more. The content of the propylene-ethylene random copolymer in the dispersed component in the sealant layer 44 is, for example, 20% by mass or less, optionally 16% by mass or less, or 12% by mass or less.

[0096] The dispersion component may include both the polyethylene described above and the elastomer described above.

[0097] The thickness of the sealant layer 44 is, for example, 30 μm or more, may be 40 μm or more, or may be 50 μm or more. The thickness of the sealant layer 44 is, for example, 70 μm or less, may be 60 μm or less, or may be 50 μm or less.

[0098] The mechanical properties of the sealant film constituting the sealant layer 44 will be described.

[0099] The sealant film preferably has a low dimensional change rate. The dimensional change rate of the sealant film can be read from the expansion rate measured by the tensile mode of thermomechanical analysis. Thermomechanical analysis is also called TMA.

[0100] The expansion rate of the sealant film is measured using a sample cut out from the sealant film after retort treatment. The retort treatment method is a spray type. The retort treatment temperature and time are 121°C and 30 minutes.

[0101] In measuring the expansion rate, a tensile force is applied to a sealant film sample held by a chuck. Then, the dimensional change of the sample is measured while changing the environment around the sample in the order of a first temperature drop step, a first temperature rise step, and a second temperature drop step. The expansion rate is calculated based on the dimensions of the sample in the first temperature rise step. The specific conditions are as follows: Length of sample between chucks: 10mm Sample width: 5mm Tensile force: 30mN First cooling step: The set temperature is lowered from 25°C to 0°C at 10°C / min, and then the set temperature of 0°C is maintained for 15 minutes. First heating step: The set temperature is raised from 0°C to 135°C at 10°C / min, and then the set temperature of 135°C is maintained for 5 minutes. Second cooling step: The set temperature is lowered from 135°C to 0°C at a rate of 10°C / min, and then the set temperature of 0°C is maintained for 15 minutes.

[0102] The expansion rate ΔL is calculated by the following formula, where the unit of the expansion rate ΔL is %. ΔL = {(L2-L1) / L1} × 100 L1 is the distance between the chucks when the set temperature is 20°C in the first heating step. L2 is the distance between the chucks when the set temperature is 20°C in the first heating step and the first heating step. The expansion rate at a temperature of 125°C in the first heating step is referred to as the dimensional change rate. FIG. 9 shows an example of the measurement results of the expansion rate of a sample during the first heating step and the first heating step by the tensile mode of TMA. The horizontal axis of FIG. 9 is the temperature around the sample. The vertical axis of FIG. 9 is the expansion rate when the distance between the chucks at a temperature of 20°C in the first heating step is used as the reference. FIG. 9 shows the result of measuring the expansion rate of the sealant film of Comparative Example 3 described later using two samples. The average value of the dimensional change rate read from the expansion rates of the two samples is adopted as the dimensional change rate of Comparative Example 3 described later.

[0103] The dimensional change rate of the sealant film in the flow direction is, for example, 5.4% or less, may be 5.0% or less, 4.5% or less, 4.2% or less, 4.0% or less, 3.8% or less, or 3.5% or less. When the dimensional change rate of the sealant film in the flow direction is 5.0% or less, the separation seal portion 20b can be appropriately peeled off to the unsealed portion 20a when the pouch 10 is heated. The dimensional change rate of the sealant film in the flow direction is, for example, 2.5% or more, may be 2.7% or more, 3.0% or more, or 3.2% or more.

[0104] In the pouch 10 shown in FIG. 1, the flow direction is the second direction D2.

[0105] The sealant film preferably has a low composite elastic modulus. The composite elastic modulus of the sealant film is measured by a nanoindentation method. Specifically, the composite elastic modulus of the sealant layer 44 made of the sealant film is measured by pressing the indenter of a nanoindenter into the cross section of the sealant layer 44 of the laminate 40.

[0106] The composite elastic modulus of the sealant layer 44 of the laminate 40 constituting the pouch 10 is measured using the laminate 40 cut out from the pouch 10 after the retort treatment. The pouch 10 is produced by folding one laminate 40 in half so that the sealant layers 44 face each other, and performing heat welding along the outer edge of the folded laminate 40. The pouch 10 is filled with 100 mL of water, and the retort treatment is performed in a state where the pouch 10 is sealed. The retort treatment is performed by hot water. The temperature and time of the retort treatment are 121°C and 30 minutes.

[0107] The indenter is pressed into the center, in the thickness direction, of the portion where the cross section of the sealant layer 44 is exposed.

[0108] The measurement conditions are as follows. A Berkovich indenter (triangular pyramid indenter) is used as the indenter of the nanoindenter. The indenter is pressed into the sealant layer 44 from the cross section of the sealant layer 44 up to a load of 30 μN over a period of 3 seconds, and is held in that state for 5 seconds, after which the indenter is unloaded over a period of 3 seconds. Based on the load and the amount of displacement while the indenter is pressed in, the maximum load P max and a load-displacement curve are obtained. Based on the trace of the indenter formed in the sealant layer 44, the contact projected area A at the maximum depth is calculated. p is measured. The trace of the indenter is a depression, also called an indentation. The composite elastic modulus is calculated from the load-displacement curve using the following formula (1).

[0109]

number

[0110] The measurement is performed in a room temperature (23° C.) environment. The measurement is performed at five or more points on the same cross section, and the composite elastic modulus is recorded as the arithmetic average value of the values ​​measured at five points with good reproducibility.

[0111] When the sealant layer 44 contains a block polypropylene, the composite elastic modulus of the sealant layer 44 can be adjusted by the mass ratio of the polymer portion (b) or the island component in the block polypropylene. For example, the higher the mass ratio of the polymer portion (b) or the island component, the lower the composite elastic modulus of the sealant layer 44.

[0112] When the sealant layer 44 contains block polypropylene, the composite modulus of the sealant layer 44 can also be determined by the content of a dispersed component such as polyethylene or elastomer. For example, the higher the content of the dispersed component, the lower the composite modulus of the sealant layer 44. For example, the lower the content of the dispersed component, the higher the composite modulus of the sealant layer 44.

[0113] The composite elastic modulus of the sealant layer 44 is, for example, 800 MPa or less, may be 750 MPa or less, or may be 700 MPa or less. When the composite elastic modulus of the sealant layer 44 is 800 MPa or less, the laminate 40 can have impact resistance even when the thickness of the sealant layer 44 is small. For example, even when the thickness of the sealant layer 44 is 50 μm or less, the pouch 10 is prevented from breaking due to the impact of being dropped, etc.

[0114] The sealant layer 44 of the present embodiment can adjust the seal strength of the laminate 40 at 100°C within an appropriate range. The seal strength at 100°C is also referred to as hot seal strength. A test piece 80 for measuring the hot seal strength of the laminate 40 is prepared by cutting the pouch 10. FIG. 10 is a plan view showing the sealed pouch 10. The outer edge seal portion of the pouch 10 includes an upper seal portion 4 formed at an upper edge 14.

[0115] The test piece 80 includes a first test piece 80A and a second test piece 80B. The first test piece 80A is a test piece for measuring the hot seal strength of the laminate 40 in the machine direction (MD). The first test piece 80A is a rectangular test piece including a long side extending in the second direction D2 and a short side extending in the first direction D1. The first test piece 80A partially includes the first side seal portion 5 or the second side seal portion 6. The first test piece 80A shown in FIG. 10 partially includes the first side seal portion 5. The second test piece 80B is a test piece for measuring the hot seal strength of the laminate 40 in the vertical direction (TD). The second test piece 80B is a rectangular test piece including a long side extending in the first direction D1 and a short side extending in the second direction D2. The second test piece 80B partially includes the upper seal portion 4. The test pieces 80A and 80B each had a long side length of 70 mm and a short side length of 15 mm.

[0116] The hot seal strength of the laminate 40 is measured using a Tensilon universal material testing machine RTC-1310A (manufactured by A&D Co., Ltd.) in accordance with JIS Z1707:1997 7.5. First, the two laminates 40 in the unsealed portion of the test piece 80 are held by the grippers 83 and 84 of the test machine (see FIG. 11). Then, the grippers 83 and 84 are pulled at a speed of 300 mm / min in opposite directions perpendicular to the surface direction of the sealed portion of the test piece 80, and the maximum value MAX of the tensile stress F1 is measured (see FIG. 12). The interval S10 between the grippers 83 and 84 at the start of pulling is 50 mm, and the interval S10 between the grippers 83 and 84 at the end of pulling is 60 mm. The maximum value MAX is adopted as the hot seal strength (see FIG. 12). The hot seal strength is measured by holding the test piece 80 in an environment with a temperature of 100°C and a relative humidity of 5% for 1 minute, and then measuring the hot seal strength in an environment with a temperature of 100°C and a relative humidity of 5%. The hot seal strength is measured for five first test pieces 80A. The average value of these values ​​is calculated as the hot seal strength of the laminate 40 in the machine direction (MD). The hot seal strength is measured for five second test pieces 80B. The average value of these values ​​is calculated as the hot seal strength of the laminate 40 in the transverse direction (TD).

[0117] In multiple test pieces 80 made from a pouch 10, if the dimensions of the sealed portion in the direction of the long side are not constant, the position at which the tensile stress F1 begins to increase, the slope of the graph as the tensile stress F1 increases, etc. may differ depending on the test piece 80, as shown in Figures 12 and 13.

[0118] The hot seal strength of the laminate 40 in the machine direction (MD) is, for example, 5.0 N or more, may be 6.0 N or more, or may be 7.0 N or more. Since the hot seal strength of the laminate 40 in the machine direction (MD) is 5.0 N or more, peeling is suppressed from progressing at the side seal portions 5, 6 when the pouch 10 is heated. The hot seal strength of the laminate 40 in the machine direction (MD) is, for example, 12.0 N or less, may be 10.0 N or less, or may be 8.0 N or less.

[0119] The hot seal strength of the laminate 40 in the transverse direction (TD) is, for example, 10.0 N or more, optionally 12.0 N or more, or 15.0 N or more. The hot seal strength of the laminate 40 in the machine direction (MD) is, for example, 20.0 N or less, optionally 18.0 N or less, or 17.0 N or less.

[0120] The ratio of the hot seal strength of the laminate 40 in the transverse direction (TD) to the hot seal strength of the laminate 40 in the machine direction (MD) is, for example, 1.8 or more, or may be 2.0 or more, or may be 2.1 or more. The ratio of the hot seal strength of the laminate 40 in the transverse direction (TD) to the hot seal strength of the laminate 40 in the machine direction (MD) is, for example, 2.5 or less, or may be 2.3 or less, or may be 2.2 or less.

[0121] <Steam release mechanism> The steam release mechanism 20 can function to release steam in the storage section 71 to the outside of the pouch 10 when the pressure in the storage section 71 exceeds a predetermined value. The steam release mechanism 20 may be provided on the first side edge 11. The steam release mechanism 20 includes an unsealed portion 20a for allowing steam to escape, and an isolating sealed portion 20b for isolating the unsealed portion 20a and the storage section 71.

[0122] The steam release mechanism 20 is located closer to the upper edge 14 of the pouch 10. That is, the steam release mechanism 20 is formed at a position closer to the upper edge 14 of the pouch 10 than to the lower edge 13 of the pouch 10. For example, the steam release mechanism 20 is provided between the upper edge 14 of the pouch 10 and a midpoint 25. The midpoint 25 is the midpoint between the upper edge 14 of the pouch 10 and the lower edge 13 of the pouch 10 in the first direction D1.

[0123] The unsealed portion 20a is a portion where the front film 1 and the back film 2 are not sealed. The unsealed portion 20a may extend to reach the first side edge 11 of the pouch 10. In this case, an opening 21 is formed between the front film 1 and the back film 2 at the first side edge 11 of the pouch 10. The unsealed portion 20a is isolated from the storage portion 71 by the isolating seal portion 20b. In this embodiment, the unsealed portion 20a is rectangular and includes a first edge 22, a second edge 23, and a third edge 24 in addition to the first side edge 11 where the opening 21 is present. The unsealed portion 20a is provided to communicate with the storage portion 71 and release steam in the pouch 10 to the outside when the pressure in the pouch 10 increases due to steam generated by heating in a microwave oven. The unsealed portion 20a protrudes from the first side edge 11 of the pouch 10 toward the storage portion 71. The unsealed portion 20a in this embodiment is composed of a front film 1 and a back film 2 that are overlapped without being thermally welded. Therefore, an opening 21 is formed in the unsealed portion 20a and is defined by the edge of the overlapping laminate.

[0124] The isolation seal portion 20b is a portion that is heat-sealed to isolate the unsealed portion 20a from the storage portion 71. The isolation seal portion 20b may include a first end connected to the lower portion 5a and a second end connected to the upper portion 5b. The width W3 of the isolation seal portion 20b may be smaller than the width W1 of the lower portion 5a. The width W3 of the isolation seal portion 20b may be, for example, 2.5 mm or more, or 3.0 mm or more. The width W3 of the isolation seal portion 20b may be, for example, 5.0 mm or less, or 4.0 mm or less. The inner edge of the isolation seal portion 20b protrudes toward the storage portion 71, and the outer edge of the isolation seal portion 20b overlaps the entire third edge 24, a part of the first edge 22, and a part of the second edge 23.

[0125] In FIG. 1, the symbol L1 indicates the distance in the second direction D2 between the inner edge of the isolating seal portion 20b and the inner edge 5a1 of the lower portion 5a. The symbol L2 indicates the distance in the second direction D2 between the inner edge of the isolating seal portion 20b and the inner edge 5b1 of the upper portion 5b. The distance L1 may be greater than the distance L2. The distance L1 may be, for example, 3 mm or more, or 6 mm or more. The distance L1 may be, for example, 15 mm or less, or 12 mm or less. By setting the distance L1 to 3 mm or more, it is possible to suppress the progression of peeling of the seal portion other than the isolating seal portion 20b. By setting the distance L1 to 15 mm or less, it is possible to suppress the flow of the contents from being hindered by the isolating seal portion 20b when the contents are filled into the pouch 10 from the opening 15 of the upper edge 14.

[0126] The distance L1 may be greater than the width W3 of the isolating seal portion 20b. In this case, the third edge 24 of the unsealed portion 20a is located inside the inner edge 5a1 of the lower portion 5a of the first side seal portion 5. That is, the unsealed portion 20a protrudes inward from the inner edge 5a1 of the lower portion 5a. The unsealed portion 30a located at the second side edge 12 does not have to protrude inward from the inner edge 6a1 of the lower portion 6a of the second side seal portion 6.

[0127] <Manufacturing method> Next, a method for producing the pouch 10 will be described.

[0128] A surface film 1 and a back film 2 made of a laminate 40 are prepared. Then, a bottom film 3 in a folded state is placed between the surface film 1 and the back film 2. The bottom film 3 may be made of a laminate 40. Then, the inner surfaces of the films are heat-sealed to each other to form seals such as a first side seal 5, a second side seal 6, a bottom seal 7, and an isolation seal 20b. The heat-sealing temperature is, for example, 160°C or higher, may be 170°C or higher, or may be 180°C or higher. The heat-sealing temperature is, for example, 250°C or lower, may be 240°C or lower, or may be 230°C or lower.

[0129] The front film 1, back film 2, and bottom film 3, which have been joined together by thermal welding, are cut into an appropriate shape. This makes it possible to obtain the pouch 10 shown in FIG. 1. Next, the contents are filled into the pouch 10 through the opening 15 at the upper edge 14. After that, the inner surface of the front film 1 and the inner surface of the back film 2 are thermally welded along the upper edge 14 to form the upper seal portion 4. In this way, it is possible to obtain the pouch 10 in which the contents are contained and sealed, as shown in FIG. 10. Thereafter, the pouch 10 may be subjected to a sterilization treatment such as boiling or retort treatment.

[0130] <How to use> A user heats the pouch 10 using a microwave oven. The moisture contained in the contents evaporates, increasing the pressure in the storage section 71. When the pressure in the storage section 71 increases, the pouch 10 expands, for example, in a circular shape around the center point C of the storage section 71. Therefore, a force is applied to each position of the sealed section of the pouch 10 in a direction from the center point C toward the sealed section. When the force applied to the isolation seal section 20b exceeds a predetermined value, the separation of the isolation seal section 20b proceeds to peel off. When the separation of the isolation seal section 20b reaches the unsealed section 20a, the unsealed section 20a is connected to the storage section 71. The steam in the storage section 71 is discharged to the outside of the pouch 10 through the unsealed section 20a. This suppresses the increase in pressure in the storage section 71.

[0131] FIG. 14 is a plan view showing the state in which the isolation seal portion 20b is peeled off. It is considered that the peeling of the isolation seal portion 20b starts at the part of the isolation seal portion 20b closest to the center point C. For example, when the inner edge 20b1 of the isolation seal portion 20b includes a corner portion where two straight portions intersect, it is considered that the peeling of the isolation seal portion 20b starts at the corner portion. When the peeling of the isolation seal portion 20b, which started at the corner portion, reaches the unsealed portion 20a, an opening is formed in the isolation seal portion 20b. The steam generated in the storage portion 71 flows into the unsealed portion 20a through the opening. The steam that has flowed into the unsealed portion 20a is discharged to the outside of the pouch 10, thereby suppressing the increase in pressure in the storage portion 71. This suppresses the peeling of the seal portions other than the isolation seal portion 20b, such as the first side seal portion 5 and the second side seal portion 6.

[0132] FIG. 15 is a plan view showing the state in which the isolating seal portion 20b is peeled off in the comparative embodiment. In the comparative embodiment, the sealant film constituting the sealant layer 44 of the laminate 40 has a high dimensional change rate. For example, the sealant film of the comparative embodiment has a dimensional change rate of 5.5% or more. For this reason, when the pouch 10 is heated, it is considered that the sealant layer 44 of the laminate 40 located at the isolating seal portion 20b is stretched more than the other layers. In this case, as shown in FIG. 15, it is considered that the progress of peeling of the isolating seal portion 20b stops before reaching the unsealed portion 20a. Such a phenomenon is called a film remaining. For example, such a phenomenon occurs when a part of the sealant layer 44 is stretched so much that it breaks.

[0133] According to this embodiment, the sealant film constituting the sealant layer 44 of the laminate 40 has a low dimensional change rate, so that the occurrence of film residue can be suppressed.

[0134] Various modifications can be made to the above-described embodiment. Below, the modified example 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 parts in the above-described embodiment will be used for parts that can be configured similarly to the above-described embodiment, and duplicated descriptions will be omitted. In addition, if it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified example, the description may be omitted.

[0135] Fig. 16 is a front view showing an example of a pouch 10. As shown in Fig. 16, the bottom of the pouch 10 does not have to have a set portion. In other words, the pouch 10 does not have to have a bottom film 3. For example, the bottom seal portion 7 of the pouch 10 may be located at the lower edge 13, and may join the inner surface of the front film 1 and the inner surface of the back film 2.

[0136] Fig. 17 is a front view showing an example of a pouch 10. As shown in Fig. 17, the surface film 1 may include a joint portion 35 in which the inner surfaces of the surface films 1 are partially overlapped. The joint portion 35 may be formed, for example, by folding back one sheet of surface film 1 at a base portion 351 to form a fold. The joint portion 35 may also be formed by overlapping portions of two sheets of surface films 1.

[0137] The joint portion 35 includes a joint seal portion 36 in which the inner surfaces of the surface film 1 are joined together. The joint seal portion 36 includes a tip seal portion 36a extending from the first side edge 11 to the second side edge 12 along the tip portion 352 of the joint portion 35. The joint seal portion 36 may further include an isolation seal portion 37b protruding from the tip seal portion 36a toward the base portion 351. The joint portion 36 may include an unsealed portion 37a isolated from the storage portion 71 by the isolation seal portion 37b. The unsealed portion 37a and the isolation seal portion 37b may be located at the center of the joint portion 35 in the second direction D2. The joint portion 35 may include a through hole 37c penetrating the surface film 15 in the unsealed portion 37a. The unsealed portion 37a, the isolation seal portion 37b, and the through hole 37c constitute the steam release mechanism 20. EXAMPLES

[0138] Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of the following examples as long as it does not depart from the gist of the present invention.

[0139] <Sealant film> Three types of sealant films were prepared.

[0140] The first type of sealant film constitutes the sealant layer 44 of the laminate 40 of the embodiment described above. The first type of sealant film includes a matrix resin component and a dispersion component. The matrix resin component is made of block polypropylene. The content of the matrix resin component in the sealant layer 44 is 51 mass % or more. The dispersion component includes polyethylene and an elastomer. The elastomer is made of a propylene-ethylene copolymer.

[0141] The second type of sealant film includes a matrix resin component and a dispersion component. The matrix resin component is made of block polypropylene. The content of the matrix resin component in the second type of sealant film is higher than the content of the matrix resin component in the first type of sealant film. The dispersion component includes polyethylene and does not include elastomer. The content of polyethylene in the dispersion component in the second type of sealant film is lower than the content of polyethylene in the dispersion component in the first type of sealant film.

[0142] The third type of sealant film includes a matrix resin component and a dispersion component. The matrix resin component is made of block polypropylene. The content of the matrix resin component in the third type of sealant film is higher than that in the second type of sealant film. The dispersion component includes polyethylene and an elastomer. The elastomer is made of an ethylene-α-olefin copolymer. The content of the polyethylene in the dispersion component in the third type of sealant film is lower than the content of the polyethylene in the dispersion component in the second type of sealant film.

[0143] FIG. 18 is a table showing the content of components contained in the first to third types of sealant films. "PP" represents the polymer portion (a) of the matrix resin component, which is made of a propylene polymer. "EPR" represents the polymer portion (b) of the matrix resin component, which is made of polyethylene and an ethylene-propylene copolymer rubber component. "PE" represents the dispersed component, which is polyethylene. "PP-PE" represents the dispersed component, which is a propylene-ethylene copolymer. "PP-α" represents the dispersed component, which is an ethylene-α-olefin copolymer.

[0144] <Example 1> The dimensional change rate of the above-mentioned first type of sealant film with a thickness of 60 μm was measured. The measuring device used was a TMA-SS7100 manufactured by Hitachi High-Tech Science Corporation. The dimensional change rate of the sealant film in the machine direction was 4.05%.

[0145] A laminate 40 having the layer structure shown in FIG. 5 was prepared using the above-mentioned first type of sealant film with a thickness of 60 μm. A biaxially stretched PET film with a thickness of 12 μm was used as the first substrate 41. A biaxially stretched PET film with a thickness of 12 μm, provided with a deposition layer 49a and a coating layer 49b, was used as the second substrate 42. The deposition layer 49a contains silicon oxide. The first substrate 41, the second substrate 42, and the sealant layer 44 were laminated by a dry lamination method to prepare the laminate 40. A solvent-based adhesive was used as the first adhesive layer 46 and the second adhesive layer 47.

[0146] The pouch 10 of Fig. 1 was produced using the laminate 40. The dimensions of each part of the pouch 10 were as follows. Dimension S1 of pouch 10 in first direction D1: 145 mm Dimension S2 of pouch 10 in second direction D2: 150 mm Distance L3 from fold-in portion 3a to bottom edge 13: 43 mm Widths W1, W4 of lower parts 5a, 6a: 6mm Width W2, W5 of upper part 5b, 6b: 10mm Width of isolation seal part 20b W3: 3mm Dimension of the opening 21 in the first direction D1: 15 mm Distance from the first side edge 11 to the inner edge of the isolation seal portion 20b in the second direction D2: 5 mm

[0147] The heat welding conditions were as follows: Heat sealing device: Heat sealer TP-701-A (manufactured by Tester Sangyosha Co., Ltd.) ·Heat welding temperature: 225℃ Heat welding pressure: 0.1MPa Heat welding time: 1 second

[0148] (Measurement of composite elastic modulus and hot seal strength) The pouch 10 was filled with 100 mL of water, and in a sealed state, a retort treatment was carried out under the following conditions. ·Method: Hot water type Retort temperature: 121℃ Retort time: 30 minutes

[0149] A portion of the laminate 40 constituting the surface film 1 of the pouch 10 for retort processing was cut out. The cut out laminate was then embedded in an embedding resin to produce a block. The block was then cut using a commercially available rotary microtome at room temperature (23°C). Cross section of block The cross section of the block shows the cross section of the sealant layer 44 of the laminate 40. The block cutting step includes a step of further cutting the laminate 40 using a diamond knife. This further smooths the cross section of the sealant layer 44.

[0150] The composite elastic modulus and hardness of the sealant layer 44 were measured by pressing the indenter of a nanoindenter into the cross section of the sealant layer 44. Specifically, a load-displacement curve was measured. The hardness measured using a nanoindenter is also called indentation hardness. As the nanoindenter, a TI950 TriboIndenter manufactured by Bruker was used. As the indenter of the nanoindenter, a Berkovich indenter (triangular pyramid indenter; Berkovich_TI0039) was used.

[0151] The composite elastic modulus was calculated from the load-displacement curve by the above-mentioned formula (1). The composite elastic modulus of the sealant layer 44 was 691.1 MPa, and the hardness was 33.2 MPa.

[0152] In addition, the hot seal strength was measured using a test piece 80 cut out from the retort pouch 10. The hot seal strength of the laminate 40 in the machine direction (MD) was 7.4 N. The hot seal strength of the laminate 40 in the transverse direction (TD) was 16.1 N.

[0153] (Rating 1 and Rating 2 Vapor Emissions) The pouch 10 was filled with 180 g of curry, and in a sealed state, the pouch 10 was subjected to a retort treatment under the following conditions. ·Method: Hot water type Retort temperature: 121℃ Retort time: 30 minutes

[0154] Next, the pouch 10 was placed in a microwave oven so that it could stand on its own. Next, the pouch 10 was heated for 3 minutes and 30 seconds in a microwave oven with an output of 600 W. The microwave oven used was a SHARP RE-TS3. Evaluations 1 and 2 were performed on the pouch 10 after heating.

[0155] In evaluation 1, it was confirmed whether peeling occurred in the first side seal portion 5 of the pouch 10. The evaluation results were classified into A, B, and C according to the distance in the second direction D2 of the peeling that occurred in the first side seal portion 5. "A" means that the distance of the peeling that occurred in the first side seal portion 5 is less than 1.0 mm. "B" means that the distance of the peeling that occurred in the first side seal portion 5 is 1.0 mm or more and less than 2.0 mm. "C" means that the distance of the peeling that occurred in the first side seal portion 5 is 2.0 mm or more. In Example 1, the result of evaluation 1 was A.

[0156] In evaluation 2, it was confirmed whether or not there was a film residue in the isolation seal portion 20b. When there was no film residue, the isolation seal portion 20b could be peeled off properly to the unsealed portion 20a, as shown in FIG. 14. When there was a film residue, signs of stretching were confirmed in the sealant layer 44 located in the isolation seal portion 20b. Depending on the presence or absence of a film residue, the evaluation result was classified as A or C. "A" means that there was no film residue. "C" means that there was a film residue. In Example 1, the result of evaluation 2 was A.

[0157] (Rating 3: Drop Strength) The pouch 10 of Fig. 1 was produced using the laminate 40. The dimensions of each part of the pouch 10 were as follows. Dimension S1 of pouch 10 in first direction D1: 260 mm Dimension S2 of pouch 10 in second direction D2: 145 mm Distance L3 from fold-in portion 3a to bottom edge 13: 45 mm

[0158] The heat welding conditions were as follows: Heat sealing device: Heat sealer TP-701-A (manufactured by Tester Sangyosha Co., Ltd.) ·Heat welding temperature: 225℃ Heat welding pressure: 0.1MPa Heat welding time: 1 second

[0159] The pouch 10 was filled with 260 mL of water, and in a sealed state, a retort treatment was carried out under the following conditions. ·Method: Hot water type Retort temperature: 121℃ Retort time: 30 minutes

[0160] After the retort treatment, the pouch 10 was stored in a thermostatic chamber set at 3° C. for one week. Immediately after the pouch 10 was removed from the thermostatic chamber, the pouch 10 was dropped 20 times from a height of 120 cm onto a test surface. The test surface was made of concrete. In 10 of the 20 drops, the pouch 10 was dropped with the lower edge 13 of the pouch 10 positioned downward. In 10 of the 20 drops, the pouch 10 was dropped with the first side edge 11 of the pouch 10 positioned downward.

[0161] The laminate 40 of the pouch 10 after the 20 drops was visually checked for breakage. Ten pouches 10 were evaluated. The evaluation results were classified into A, B, and C according to the state of breakage. "S" means that the first substrate 41, the second substrate 42, and the sealant layer 44 of the laminate 40 were not broken in all of the ten pouches 10. "A" means that the first substrate 41 and the second substrate 42 were not broken in all of the ten pouches 10, but breakage occurred in the sealant layer 44. "B" means that the first substrate 41, the second substrate 42, and the sealant layer 44 were broken in one of the ten pouches 10, and water was leaking. "B" means that the first substrate 41, the second substrate 42, and the sealant layer 44 were broken in two or more of the ten pouches 10, and water was leaking. In Example 1, the result of Evaluation 3 was S.

[0162] The measurement results and evaluation results in Example 1 are shown in Figure 19. "CPP1" means that the first type of sealant film was used. "TMA" means the dimensional change rate calculated based on the expansion rate measured by the tensile mode of thermomechanical analysis.

[0163] <Example 2> A laminate 40 and a pouch 10 were produced and measured and evaluated in the same manner as in Example 1. Except for the fact that the thickness of the sealant layer 44 is 50 μm, the laminate 40 and the pouch 10 of Example 2 are the same as the laminate 40 and the pouch 10 of Example 1. The measurement results and evaluation results in Example 2 are shown in FIG.

[0164] <Example 3> A laminate 40 and a pouch 10 were produced and measured and evaluated in the same manner as in Example 1. Except for the thickness of the sealant layer 44 being 40 μm, the laminate 40 and the pouch 10 of Example 3 are the same as the laminate 40 and the pouch 10 of Example 1. The measurement results and evaluation results in Example 3 are shown in FIG.

[0165] <Comparative Example 1> A laminate 40 and a pouch 10 were produced and measured and evaluated in the same manner as in Example 1. The laminate 40 and the pouch 10 of Comparative Example 1 are the same as the laminate 40 and the pouch 10 of Example 1, except that a second type of sealant film having a thickness of 60 μm was used as the sealant layer 44. The measurement results and evaluation results in Comparative Example 1 are shown in FIG. 19. "CPP2" means that the second type of sealant film was used.

[0166] <Comparative Example 2> A laminate 40 and a pouch 10 were produced and measured and evaluated in the same manner as in Example 1. Except for the fact that the thickness of the sealant layer 44 is 50 μm, the laminate 40 and the pouch 10 of Comparative Example 2 are the same as the laminate 40 and the pouch 10 of Comparative Example 1. The measurement results and evaluation results of Comparative Example 2 are shown in FIG.

[0167] <Comparative Example 3> A laminate 40 and a pouch 10 were produced and measured and evaluated in the same manner as in Example 1. The laminate 40 and the pouch 10 of Comparative Example 3 are the same as the laminate 40 and the pouch 10 of Example 1, except that a third type of sealant film having a thickness of 60 μm was used as the sealant layer 44. The measurement results and evaluation results in Comparative Example 3 are shown in FIG. 19. "CPP3" means that a third type of sealant film was used.

[0168] In Comparative Examples 1 and 2, the result of Evaluation 1 was C. It is believed that in Comparative Examples 1 and 2, peeling of the first side seal portion 5 was likely to progress because the hot seal strength of the laminate 40 was low. In Examples 1 to 3, peeling of the first side seal portion 5 was likely to be suppressed because the hot seal strength of the laminate 40 was 6.0 N or more.

[0169] In Comparative Example 3, the result of Evaluation 2 was C. In Comparative Example 3, the dimensional change rate of the sealant film was 5.5%, which is believed to have caused the sealant layer 44 located at the isolation seal portion 20b to easily elongate. In Examples 1 to 3, the dimensional change rate of the sealant film was 5.0% or less, which is believed to have caused no film residue.

[0170] In Comparative Examples 2 and 3, the result of Evaluation 3 was C. In Comparative Example 2, since the composite elastic modulus of the sealant film was 800 MPa or more and the thickness of the sealant film was 50 μm or less, it is believed that the laminate 40 was easily broken. In Comparative Example 2, since the composite elastic modulus of the sealant film was 830 MPa or more, it is believed that the laminate 40 was easily broken. In Examples 1 to 3, since the composite elastic modulus of the sealant film was 700 MPa, it is believed that even when the thickness of the sealant film was small as in Example 3, the breakage of the laminate 40 was suppressed. [Explanation of symbols]

[0171] 1 Surface film 2 Back film 3 Bottom film 3a Folding part 3b~3e Second cutout 3f Bottom film part 1 3g Second part of bottom film 4 Upper seal part 5 First side seal 6 Second side seal 7 Bottom seal 7a First bottom seal 7b Second bottom seal 9 Bottom gusset 11 1st side edge 12 Second side edge 13 Lower edge 14 Upper edge 15 Opening 20 Steam release mechanism 21 Aperture 20a Unsealed part 20b Isolation seal part 22 First Edge 23 The Second Edge 24 The Third Edge 40 Laminate 41 First base material 42 Second base material 43 Third base material 44 Sealant Layer 45 Printing layer 46 First adhesive layer 47 Second adhesive layer 48 3rd adhesive layer 49a Deposited layer 49b Coating layer 71 Storage unit

Claims

1. A sealant film for use in a laminate constituting a pouch for use in a microwave oven, comprising: A matrix resin component made of block polypropylene and a dispersion component containing at least polyethylene, A sealant film, wherein the dimensional change rate of the sealant film in the machine direction from 20°C to 125°C in a tensile mode of TMA is 5.0% or less.

2. 2. The sealant film of claim 1, having a composite modulus of 800 MPa or less.

3. The sealant film according to claim 1 or 2, having a thickness of 40 μm or more and 60 μm or less.

4. The sealant film according to claim 3, having a thickness of 40 μm or more and 50 μm or less.

5. The sealant film according to claim 1 or 2, which consists of a single layer.

6. A laminate for forming a microwave pouch, comprising: A sealant layer comprising the sealant film according to claim 1 or 2; a first substrate located outside the sealant layer in a thickness direction of the laminate, the first substrate including a biaxially oriented plastic film.

7. The laminate according to claim 6 , further comprising a second substrate located between the first substrate and the sealant layer in the thickness direction and including a biaxially oriented plastic film.

8. the first substrate comprises polyester; The laminate of claim 7 , wherein the second substrate comprises polyester or polyamide.

9. A microwave pouch comprising: A front surface film and a back surface film each having the laminate according to claim 6; a seal portion that joins the sealant layer of the front surface film and the sealant layer of the back surface film; and a steam venting mechanism.

10. The seal portion includes an outer edge seal portion located on an outer edge of the pouch, The pouch according to claim 9 , wherein the steam release mechanism includes an isolating seal portion that protrudes from the outer edge seal portion toward the containing portion, and an unsealed portion that is isolated from the containing portion by the isolating seal portion.

11. The pouch according to claim 10, wherein the seal strength in the machine direction of the outer edge seal portion at 100°C is 6.0 N or more and 12.0 N or less.

12. 12. The pouch of claim 11, wherein the ratio of the seal strength of the perimeter seal in the perpendicular direction at 100°C to the seal strength of the perimeter seal in the machine direction at 100°C is 1.8 or greater.

Images