Laminate and bag-shaped container

Abstract

To prevent warpage from occurring when bag products are put on one another into a bundle.SOLUTION: A laminate has a printed layer, a seal layer and an intermediate layer that are superposed on one another. The total relaxation time is 0.83 rad / s or more and 1.60 rad / s or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate and a bag-like container.

Background Art

[0002] Conventionally, films made of polypropylene-based resins have been widely used as packaging films including bread packaging, taking advantage of their excellent rigidity, transparency, moisture resistance, etc. As a technology related to bread packaging films, there is one described in Patent Document 1. A bread packaging bag is obtained by folding the film in half, inserting a gusset at the bottom, and further heat-sealing both side portions. The obtained gusset bags are stacked in bundles of, for example, 500 units and then packed in boxes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the bread packaging bag obtained from the film described in Patent Document 1, when stacked in bundles, warping occurs at the ends of the bundle, and the packaging has to be done so that the ends do not break, resulting in a problem of reduced work efficiency.

[0005] Therefore, an object of the present invention is to provide a laminate and a bag-like container capable of suppressing warping that occurs when bag products are stacked in bundles.

Means for Solving the Problems

[0006] [1] A laminate in which a printing layer, a seal layer, and an intermediate layer are laminated, and the overall relaxation time is 0.8 3s or more and 1.6 0s or less. [2] The relaxation time of the intermediate layer is 0. 5s or more and 1. 3s or less, the laminate according to [1]. [3] The intermediate layer contains at least one of a metallocene catalyst-based polypropylene or a metallocene catalyst-based polyethylene, the laminate according to [1] or [2]. [4] The content of the metallocene catalyst-based polypropylene or the metallocene catalyst-based polyethylene in the intermediate layer is 1% by mass or more and 95% by mass or less, the laminate according to [3]. [5] The intermediate layer contains at least one of a random polypropylene or a homopolypropylene, the laminate according to [3] or [4]. [6] The intermediate layer contains an elastomer, the laminate according to any one of [1] to [5]. [7] The content of the elastomer in the intermediate layer is 1% by mass or more and 40% by mass or less, the laminate according to [6]. [8] The intermediate layer contains polyethylene, the laminate according to any one of [1] to [7]. [9] The polyethylene content of the intermediate layer is 40% by mass or less, the laminate according to [8].

[10] The seal layer contains a random polypropylene, the laminate according to any one of [1] to [9].

[11] The printing layer contains at least one of a random polypropylene or a block polypropylene, the laminate according to any one of [1] to

[10] .

[12] At least one of the printing layer, the intermediate layer or the seal layer contains a plant-derived resin, the laminate according to any one of [1] to

[11] .

[13] The plant-derived resin is at least one of bio-polyethylene or bio-polypropylene, the laminate according to

[12] .

[14] A bag-like container using the laminate according to any one of [1] to

[13] formed into a film shape.

[15] The bag-like container according to

[14] , having a gusset portion.

[16] The bag-like container according to

[14] or

[15] , for bread packaging.

Advantages of the Invention

[0007] According to the laminate and the bag-like container of the present invention, it is possible to suppress the warping that occurs when bagged products are stacked and bundled.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0010] FIG. 1 is a schematic cross-sectional view showing the structure of a laminate according to an embodiment of the present invention. As shown in FIG. 1, the laminate 10 has a printing layer 11, an intermediate layer 12, and a seal layer 13. The laminate 10 is formed into a film shape with a thickness suitable for forming a bag-like container as described later, specifically, for example, a thickness of 15 μm or more and 100 μm or less, preferably 20 μm or more and 50 μm or less, more preferably 25 μm or more and 30 μm or less, but is not limited to this example. The relaxation time of the entire laminate 10 is 0.8 3s or more and 1.6 0s or less. The relaxation time of the entire laminate 10 is preferably 0.8 5s or more, more preferably 0.9 0s or more. Also, the relaxation time of the entire laminate 10 is preferably 1.5 5s or less, preferably 1.5 0sThe following is more preferable. This is because when the relaxation time is too short, the neck-in during manufacturing becomes excessive, resulting in a large shrinkage amount due to the large shrinkage, and when the relaxation time is too long, the residual stress of the film becomes large, resulting in a large shrinkage amount. Here, the relaxation time can be calculated as the representative relaxation time from the shear flow characteristics of the press piece, as will be described in the examples below.

[0011] The printing layer 11 is the layer on which printing is formed when manufacturing a container using the laminate 10. The printing layer 11 contains a propylene-based resin as a main component, and contains, for example, homopolypropylene, random polypropylene, or block polypropylene. In the present invention, the main component refers to the resin having the largest content among the resins contained. Preferably, it is 50% by mass or more of the resin content, more preferably 70% by mass or more, and still more preferably 85% by mass or more. The upper limit is usually 100% by mass, but the inclusion of impurities is allowed. The printing layer 11 preferably contains at least either random polypropylene or block polypropylene as a main component.

[0012] The intermediate layer 12 is formed between the printing layer 11 and the seal layer 13, and is a layer that imparts impact resistance and fracture resistance to the laminate 10. The intermediate layer 12 contains at least either a propylene-based resin or a polyethylene-based resin as a main component. In order to make the relaxation time of the entire laminate 10 within the above range, the relaxation time of only the intermediate layer 12 is preferably 0. 4s 1.0 or more 3s 1.0 or less is preferable, and 0. 5s 1.0 or more 0s 1.0 or less is more preferable, 0.6 0s 0.9 or more 5s 0.9 or less is still more preferable, 0.6 5s 0.9 or more 0s 0.9 or less is particularly preferable.

[0013] For example, the intermediate layer 12 may achieve the above relaxation time by containing a propylene-based resin or a polyethylene-based resin with a short relaxation time, specifically, either or both of a metallocene catalyst-based polypropylene or a metallocene catalyst-based polyethylene. In this case, the content of the metallocene catalyst-based polypropylene in the intermediate layer 12 is preferably 5% by mass or more and 95% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 60% by mass or less. Also, the content of the metallocene catalyst-based polyethylene in the intermediate layer 12 is preferably 1% by mass or more and 50% by mass or less, more preferably 3% by mass or more and 40% by mass or less, and even more preferably 5% by mass or more and 30% by mass or less. Further, when the metallocene catalyst-based polypropylene and the metallocene catalyst-based polyethylene are used in combination in the intermediate layer 12, the total content is preferably 1% by mass or more and 95% by mass or less, more preferably 1% by mass or more and 80% by mass or less, even more preferably 3% by mass or more and 60% by mass or less, and particularly preferably 5% by mass or more and 60% by mass or less. When the intermediate layer 12 contains the metallocene catalyst-based polypropylene, it may further contain random polypropylene, homopolypropylene, or a mixture thereof. This is because if only the metallocene catalyst-based polypropylene with a slow crystallization rate is used, crystallization may progress and shrinkage may occur during the winding process of manufacturing the laminate. Also, when the intermediate layer 12 contains the metallocene catalyst-based polyethylene, it may further contain random polypropylene, homopolypropylene, or a mixture thereof. This is because if only the metallocene catalyst-based polyethylene is used, the rigidity required for the package may be insufficient. In each of the above cases, the content of the random polypropylene, homopolypropylene, or a mixture thereof in the intermediate layer 12 is preferably 5% by mass or more and 95% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 60% by mass or less.

[0014] Further, for example, the intermediate layer 12 may achieve the above relaxation time by containing an elastomer. Alternatively, the intermediate layer 12 may achieve the above relaxation time by using an elastomer in combination with a metallocene catalyst-based polypropylene or a metallocene catalyst-based polyethylene. The content of the elastomer in the intermediate layer 12 is, for example, 1% by mass or more, preferably 3% by mass or more. Also, the content of the elastomer in the intermediate layer 12 is, for example, 40% by mass or less, preferably 10% by mass or less. Examples of the elastomer include ethylene-propylene copolymer elastomer (EPR), ethylene-butene copolymer elastomer (EBR), or ethylene-hexene copolymer elastomer (EHR). When an elastomer is used in combination with a metallocene catalyst-based polypropylene or a metallocene catalyst-based polyethylene, the total content thereof in the intermediate layer 12 is, for example, 2% by mass or more, preferably 8% by mass or more. Also, the above total content is, for example, 100% by mass or less, preferably 70% by mass or less.

[0015] The seal layer 13 is a layer that is joined to the seal layer of the opposing laminate 10 or another resin molded product when manufacturing a container using the laminate 10. The seal layer 13 contains a propylene-based resin as a main component, and the propylene-based resin preferably contains random polypropylene. The content of random polypropylene in the seal layer 13 is preferably 50% by mass or more and 100% by mass or less. By containing random polypropylene in the seal layer 13, the heat sealability can be improved. Also, the seal layer 13 preferably contains polyethylene, more preferably linear low density polyethylene, in order to impart easy-openability. The content of linear low density polyethylene is preferably 5% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 40% by mass or less. The upper limit of the density of the linear low density polyethylene contained in the seal layer is preferably 3 0.920 g / cm or less, more preferably 3 0.910 g / cm or less, still more preferably 3The following applies. The lower limit of the density of the linear low-density polyethylene contained in the seal layer is preferably 0.850 g / cm 3 or more, more preferably 0.860 g / cm 3 or more, still more preferably 0.870 g / cm 3 or more. The melt flow rate (MFR) of the linear low-density polyethylene contained in the seal layer is preferably 0.5 g / 10 min or more and 15 g / 10 min or less.

[0016] At least one of the printing layer 11 or the seal layer 13 may contain a plant-derived resin in addition to the above components. In this case, the plant-derived resin may be biopolyethylene or biopolypropylene. Biopolypropylene can be obtained, for example, by fermenting molasses of sorghum, which is a non-edible plant, with microorganisms to produce an intermediate material and then dehydrating it. On the other hand, when at least one of the printing layer 11 or the seal layer 13 contains biopolyethylene, the content of biopolyethylene in the printing layer 11 or the seal layer 13 is preferably 3% by mass or more and 60% by mass or less, more preferably 50% by mass or less. The biopolyethylene is not particularly limited, but is preferably low-density polyethylene or linear low-density polyethylene, and more preferably linear low-density polyethylene from the viewpoint of improving mechanical properties. The density of the biopolyethylene contained in the printing layer 11 or the seal layer 13 is, for example, 0.900 g / cm 3 or more, preferably 0.905 g / cm 3 or more, more preferably 0.910 g / cm 3 or more, from the viewpoint of achieving both rigidity and impact strength. Also, the density of the biopolyethylene contained in the printing layer 11 or the seal layer 13 is, for example, 0.950 g / cm 3 or less, preferably 0.940 g / cm 3 or less, more preferably 0.930 g / cm 3The following applies. Also, the melt flow rate (MFR) of the biopolyethylene contained in the printing layer 11 or the seal layer 13 is, from the viewpoint of film formability, for example, 0.1 g / 10 min or more, preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more. Also, the MFR of the biopolyethylene contained in the printing layer 11 or the seal layer 13 is, from the viewpoint of film formability, for example, 15.0 g / 10 min or less, preferably 10.0 g / 10 min or less, more preferably 5.0 g / 10 min or less. Thus, by containing at least one of the layers with biopolyethylene or biopolypropylene, the environmental load can be reduced.

[0017] Further, the intermediate layer 12 may contain polyethylene other than metallocene-catalyzed polyethylene in addition to the above-described metallocene-catalyzed polypropylene, metallocene-catalyzed polyethylene, or elastomer. The content of polyethylene other than metallocene-catalyzed polyethylene in the intermediate layer 12 is preferably 0.1% by mass or more and 40% by mass or less, more preferably 3% by mass or more and 40% by mass or less. By the intermediate layer 12 containing polyethylene other than metallocene-catalyzed polyethylene, the impact resistance of the laminate 10 is improved, and an improvement in seal strength when fusion-sealing in the manufacturing process of the bag-like container is expected. The polyethylene other than metallocene-catalyzed polyethylene contained in the intermediate layer 12 may be biopolyethylene, polyethylene other than metallocene-catalyzed polyethylene other than that, or a mixture thereof. When using biopolyethylene, it is also possible to make the total amount of the above content biopolyethylene. The content of biopolyethylene in the intermediate layer 12 is, for example, 1% by mass or more, preferably 3% by mass or more. Also, the content of biopolyethylene in the intermediate layer 12 is, for example, 60% by mass or less, preferably 50% by mass or less. The biopolyethylene is not particularly limited, but is preferably low-density polyethylene or linear low-density polyethylene, and more preferably linear low-density polyethylene from the viewpoint of improving mechanical properties. The density of the biopolyethylene is, from the viewpoint of achieving both rigidity and impact resistance, for example, 0.900 g / cm3 or more, preferably 0.905 g / cm 3 or more, more preferably 0.910 g / cm 3 or more. Further, the density of the biopolyethylene is, from the viewpoint of achieving both rigidity and impact strength, for example, 0.950 g / cm 3 or less, preferably 0.940 g / cm 3 or less, more preferably 0.930 g / cm 3 or less. Further, the melt flow rate (MFR) of the biopolyethylene is, from the viewpoint of film formability, for example, 0.1 g / 10 min or more, preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more. Also, the MFR of the biopolyethylene is, from the viewpoint of film formability, for example, 15.0 g / 10 min or less, preferably 10.0 g / 10 min or less, more preferably 5.0 g / 10 min or less. Thus, by using biopolyethylene, in addition to the above effects, the environmental load can be reduced. Further, the intermediate layer 12 may contain a polypropylene other than a metallocene catalyst-based polypropylene. The polypropylene other than the metallocene catalyst-based polypropylene contained in the intermediate layer 12 may be bio-polypropylene, or may be another polypropylene other than the metallocene catalyst-based polypropylene, or may be a mixture thereof. When using bio-polypropylene, it is also possible to make the total amount of the above content bio-polypropylene.

[0018] The following are exemplified as cases where at least one of the printing layer 11, the intermediate layer 12, or the seal layer 13 contains a plant-derived resin. For each of Example 1 and Example 2, the types of raw materials used and the physical properties in the printing layer, the intermediate layer, and the seal layer are described, and the blending amounts are shown in a table. Note that for each example, the types of raw materials, physical properties, and blending amounts are examples and can be adjusted as appropriate.

[0019] (Example 1) Printing layer: Random polypropylene (MFR: 7.8 g / 10 min, density 0.900 g / cm 3, Melting point: 138°C), Bio-polyethylene (Bio-linear low-density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 )

[0020] Intermediate layer: Homopolypropylene (MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , Melting point: 160°C), Metallocene-catalyzed random polypropylene (MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , Melting point: 135°C), Bio-polyethylene (Bio-linear low-density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 ), Elastomer (Tufmer (P-0280) manufactured by Mitsui Chemicals, Ethylene-propylene copolymer elastomer (EPR))

[0021] Sealing layer: Random polypropylene (MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , Melting point: 134°C), Linear low-density polyethylene (MFR: 3.0 g / 10 min, density 0.875 g / cm 3 ), Bio-polyethylene (Bio-linear low-density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 )

[0022]

Table 1

[0023] (Example 2) Printing layer: Block polypropylene (MFR: 8.5 g / 10 min, density 0.900 g / cm 3 , Melting point: 160°C), Bio-polyethylene (Bio-linear low-density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 )

[0024] Intermediate layer: Homopolypropylene (MFR: 7.0 g / 10 min, density: 0.900 g / cm 3, Melting point: 160 °C), metallocene catalyst-based random polypropylene (MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , Melting point: 135 °C), bio polyethylene (bio linear low density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 ), elastomer (Tufmer (P-0280) manufactured by Mitsui Chemicals, ethylene - propylene copolymer elastomer (EPR))

[0025] Sealing layer: random polypropylene (MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , Melting point: 134 °C), linear low density polyethylene (MFR: 3.0 g / 10 min, density 0.875 g / cm 3 ), bio polyethylene (bio linear low density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 )

[0026]

Table 2

[0027] Note that in the laminate 10, additional layers may be laminated in addition to the above-mentioned printing layer 11, intermediate layer 12, and sealing layer 13.

[0028] Figure 2 is a diagram schematically showing the manufacturing process of a bag-like container using the laminate according to an embodiment of the present invention. In the illustrated example, (1) a long laminate 10 formed in a film shape is pulled out from the raw material roll 1, (2) it is vertically folded in half so that the sealing layer 13 becomes the inner surface, and further (3) the folded portion is gusset-folded, and in that state, it is cut to the width of the bag using a fusion sealing machine 2 and both sides are sealed. (4) In the bag 3 thus manufactured, a gusset portion 4 is formed at the bottom, and the edge of the film forming the opening 5 is in the longitudinal direction (MD) of the raw material roll 1. (5) The bags 3 are stacked in bundles, for example, in units of 500, and fixed and packed by passing pins 6 through pinholes.

[0029] FIG. 3 is a diagram for explaining problems that can occur in the bag-shaped container of the example shown in FIG. 2. In the illustrated example, the original roll rolls 1A and 1B are manufactured by cutting the mill roll 7 in the width direction and removing the ears 8. At this time, the bag 3A formed from the original roll 1A cut out from the central portion of the mill roll 7 has a small warp, but the bag 3B formed from the original roll 1B cut out from the end portion of the mill roll 7 has a large warp. This is because when the mill roll 7 is formed by coextrusion molding such as the T-die method, the film is stretched to suppress necking at the end of the die, resulting in residual stress, and the shrinkage amount after manufacturing becomes large. In the bag 3B, among the edges 5A and 5B of the film forming the opening, the shrinkage amount of the edge 5B closer to the end of the mill roll 7 is large, and a dimensional difference occurs between the edges 5A and 5B, resulting in a large warp when stacked into a bundle.

[0030] Therefore, the inventors of the present invention attempted to equalize the shrinkage amount between the central portion and the end portion of the mill roll 7 by controlling the relaxation time of the laminate 10. When the relaxation time is shortened, both the central portion and the end portion of the mill roll 7 relax early during the manufacture of the mill roll 7, and as a result, the residual stress becomes relatively small and uniform. However, if the relaxation time is too short, the necking during manufacture becomes excessive, resulting in a large shrinkage amount. Therefore, it is necessary to control the relaxation time within an appropriate range. The relaxation time of the laminate 10 can be controlled by adjusting the content of the short relaxation time raw material in the intermediate layer 12, specifically, the metallocene catalyst-based polypropylene. Note that the short relaxation time raw material is not limited to the metallocene catalyst-based raw material, and an appropriate raw material with a small high molecular weight component can be used.

Example

[0031] Examples of the laminate according to the embodiment of the present invention as described above and the bread packaging bag using the laminate formed into a film shape will be described below.

[0032] The examples and comparative examples were carried out according to the procedures as described below. (1) Forming of the film-shaped laminate A three-layer laminate having a printing layer, an intermediate layer, and a seal layer was formed into a film by multi-layer co-extrusion T-die casting molding. (2) Manufacture of bread packaging bags Using the high-speed side-welded automatic bag-making machine "HK-65V" manufactured by Totani Giken Kogyo Co., Ltd., bags were manufactured by the process described with reference to FIG. 2 above. (3) Measurement of warpage amount (1) Five hundred bags obtained in (1) were stacked and bundled, and the height of the end portion on the opening side of the bundle in a state fixed by passing a pin was measured as the warpage amount.

[0033] [Example 1] (1) Printing layer [Raw material] Random polypropylene (propylene·ethylene copolymer, MFR: 7.8 g / 10 min, density 0.900 g / cm 3 , melting point: 138 °C) 100.0 mass% [Thickness] 4.7 μm (2) Intermediate layer [Raw material] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 20.0 mass%, metallocene catalyst-based random polypropylene (metallocene catalyst-based propylene·ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 80.0 mass% [Thickness] 19.7 μm (3) Seal layer [Raw material] Random polypropylene (propylene·ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 134 °C) 73.0 mass%, linear low-density polyethylene (ethylene·α-olefin copolymer, MFR: 3.0 g / 10 min, density 0.875 g / cm 3 ) 27.0 mass% [Thickness] 3.6 μm

[0034] [Example 2] Except for the constituent components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw material] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 40.0 mass%, metallocene catalyst-based random polypropylene (metallocene catalyst-based propylene-ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 60.0 mass% [Thickness] 19.7 μm

[0035] [Example 3] Except for the constituent components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw material] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 60.0 mass%, metallocene catalyst-based random polypropylene (metallocene catalyst-based propylene-ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 40.0 mass% [Thickness] 19.7 μm

[0036] [Example 4] Except for the constituent components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw material] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 70.0 mass%, metallocene catalyst-based random polypropylene (metallocene catalyst-based propylene-ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 30.0 mass% [Thickness] 19.7 μm

[0037] [Example 5] Except for the constituent components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw materials] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 58.0 mass%, metallocene catalyst system random polypropylene (metallocene catalyst system propylene·ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 38.0 mass%, biopolyethylene (linear low density polyethylene, MFR: 2.3 g / 10 min, density: 0.916 g / cm 3 ) 4.0 mass% [Thickness] 19.7 μm

[0038] [Example 6] Except for the components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw materials] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 95.0 mass%, elastomer (Tafmer (P-0280) manufactured by Mitsui Chemicals) 5.0 mass% [Thickness] 19.7 μm

[0039] [Example 7] Except for the components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw materials] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 75.0 mass%, metallocene catalyst system random polypropylene (metallocene catalyst system propylene·ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 20.0 mass%, elastomer (Tafmer (P-0280) manufactured by Mitsui Chemicals) 5.0 mass% [Thickness] 19.7 μm

[0040] [Comparative Example 1] Except for the components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw materials] Homopolypropylene (propylene homopolymer, MFR: 7.0 g / 10 min, density: 0.900 g / cm 3 , melting point: 160 °C) 100.0 mass% [Thickness] 19.7 μm

[0041] [Comparative Example 2] Except for the constituent components of the following intermediate layer, the same procedure as in Example 1 was followed. (1) Intermediate layer [Raw materials] Metallocene catalyst-based random polypropylene (metallocene catalyst-based propylene / ethylene copolymer, MFR: 7.0 g / 10 min, density 0.900 g / cm 3 , melting point: 135 °C) 100.0 mass% [Thickness] 19.7 μm

[0042] For the films obtained in Examples 1 to 7 and Comparative Examples 1 and 2, press pieces with a thickness of 1.0 mm were prepared using a 50 t press machine (TJ-S5030SM) manufactured by Tokyo Sangyo Co., Ltd. The shear flow characteristics of the press pieces were measured with a rheometer (Physica MCR302) manufactured by Anton Paar, and the representative relaxation time was determined.

[0043] For Examples 1 to 7 and Comparative Examples 1 and 2, Table 3 shows the measurement results of the maximum height (warp amount) of the bundle of bags and the representative relaxation time. The warp determination was such that a warp amount of less than 4.0 cm was considered OK, and a warp amount of 4.0 cm or more was considered NG.

[0044] [Table 3]

[0045] [Evaluation Results] As is clear from the results shown in Table 3, it was confirmed that in the bread packaging bags of Examples 1 to 7, the warping that occurs when the bags are stacked into a bundle is suppressed.

[0046] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to these examples. It is obvious that those skilled in the technical field to which the present invention pertains can conceive of various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present invention.

Explanation of Reference Numerals

[0047] 10... laminate, 11... printing layer, 12... intermediate layer, 13... seal layer, 1, 1A, 1B... raw material roll, 2... fusing and sealing machine, 3, 3A, 3B... bag, 4... gusset part, 5... opening, 5A, 5B... edge, 6... pin, 7... mill roll, 8... ear.

Claims

1. A laminate in which a printing layer, an intermediate layer, and a seal layer are laminated in this order, wherein the representative relaxation time at an overall angular frequency ω = 0.1 rad / s is 0.83 s or more and 1.60 s or less, the intermediate layer is mainly composed of a polypropylene-based resin, the mass ratio of homopolypropylene in the polypropylene-based resin is 20% or more and 70% or less, and the balance of the polypropylene-based resin is a metallocene-based catalyst random polypropylene.

2. A laminate in which a printing layer, an intermediate layer, and a seal layer are laminated in this order, wherein the representative relaxation time at an overall angular frequency ω = 0.1 rad / s is 0.83 s or more and 1.60 s or less, the intermediate layer is mainly composed of a polypropylene-based resin and further contains 3% by mass or more and 10% by mass or less of an elastomer, and the polypropylene-based resin is homopolypropylene or a mixture of 78% by mass or more of homopolypropylene and the balance of a metallocene catalyst random polypropylene, and the seal layer contains 5% by mass or more and 50% by mass or less of linear low density polyethylene.

3. The laminate according to claim 2, wherein the elastomer contains at least one of an ethylene-propylene copolymer elastomer (EPR), an ethylene-butene copolymer elastomer (EBR), or an ethylene-hexene copolymer elastomer (EHR).

4. The laminate according to any one of claims 1 to 3, wherein the representative relaxation time of the intermediate layer at an angular frequency ω = 0.1 rad / s is 0.5 s or more and 1.3 s or less.

5. The laminate according to any one of claims 1 to 4, wherein the intermediate layer contains polyethylene.

6. The laminate according to claim 5, wherein the polyethylene content of the intermediate layer is 40% by mass or less.

7. The laminate according to any one of claims 1 to 6, wherein the seal layer contains random polypropylene.

8. The laminate according to any one of claims 1 to 7, wherein the printing layer contains at least one of random polypropylene or block polypropylene.

9. The laminate according to any one of claims 1 to 8, wherein at least one of the printing layer, the intermediate layer, or the seal layer contains a plant-derived resin.

10. The laminate according to claim 9, wherein the plant-derived resin is at least one of biopolyethylene or biopolypropylene. **Claim 11** A bag-shaped container using the laminate according to any one of claims 1 to 10, formed into a film shape. **Claim 12** The bag-shaped container according to claim 11, having a gusset portion. **Claim 13** The bag-shaped container according to claim 11 or claim 12, for packaging bread.

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