Laminate and packaging bag

Abstract

To provide a laminate and a packaging bag which are excellent in recyclability and have excellent strength.SOLUTION: A laminate 10 has at least a first layer 11, a second layer 12, and an intermediate layer 13 laminated so as to contact the first layer 11 and the second layer 12, wherein main components of the first layer 11, the second layer 12 and the intermediate layer 13 are polyolefin-based resins, the first layer 11, the second layer 12 and the intermediate layer 13 are arranged so as to be directly adjacent to each other in a thickness direction of the laminate 10, the first layer 11 is a base material layer, the second layer 12 is a sealant layer, and a ratio of thickness of the first layer 11 to thickness of the intermediate layer 13 is 1:1.6 or more and 2.8 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate and a packaging bag. [Background technology]

[0002] A conventional packaging bag is a standing pouch having a bottom film disposed between a pair of body films and capable of standing upright. Patent Document 1 describes the use of a packaging bag made of a laminate film having a sealant as the innermost layer and a stretched film as the base material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-7630 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, from the perspective of efficient resource utilization, there has been a demand to use recyclable materials and conserve petroleum resources. However, laminated films that combine multiple materials have the problem that they require time and effort to separate the materials, making them difficult to recycle. To address this issue, containers made from single-material (mono-material) film materials are being considered as materials suitable for recycling.

[0005] However, when an adhesive is used between the substrate and the sealant in a packaging bag made from a mono-material film, there is a problem that the adhesive becomes a dissimilar material. Mono-material films tend to have weaker seal strength than conventional laminated films that combine multiple materials, and there is a risk of the bag breaking if subjected to impact during transportation, etc.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminate and a packaging bag that are highly recyclable and have excellent strength. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a laminate having at least a first layer, a second layer, and an intermediate layer laminated in contact with the first layer and the second layer, wherein the first layer, the second layer, and the intermediate layer are mainly composed of a polyolefin resin, the first layer, the second layer, and the intermediate layer are arranged directly adjacent to each other in the thickness direction of the laminate, the first layer is a base layer, the second layer is a sealant layer, and the ratio of the thickness of the first layer to the thickness of the intermediate layer is 1:1.6 or more and 2.8 or less.

[0008] The present invention also provides a laminate having at least a first layer, a second layer, and an intermediate layer laminated in contact with the first layer and the second layer, wherein the first layer, the second layer, and the intermediate layer are mainly composed of a polyolefin resin, the first layer, the second layer, and the intermediate layer are arranged directly adjacent to each other in the thickness direction of the laminate, the first layer is a base layer, the second layer is a sealant layer, and the ratio of the thickness of the second layer to the thickness of the intermediate layer is 1:0.5 or more and 1.5 or less.

[0009] The polyolefin resin may be at least one of a polyethylene resin and a polypropylene resin. At least one of the surfaces of the first layer or the second layer facing the intermediate layer may be subjected to an oxidation treatment.

[0010] The present invention also provides a packaging bag using the laminate. The packaging bag may be for packaging liquids. The packaging bag may be a stand-up pouch. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a laminate and a packaging bag having excellent recyclability and strength. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a front view illustrating an example of an apparatus for manufacturing a laminate. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described below based on preferred embodiments. The laminate of the embodiment has at least a first layer, a second layer, and an intermediate layer laminated in contact with the first layer and the second layer. In this specification, the main component preferably accounts for at least 50% by mass or more, and may account for 80% by mass or more.

[0014] (1st layer) The first layer may be, for example, a base layer. The main component of the first layer is a polyolefin resin. The main component of the first layer may be a polyethylene resin or a polypropylene resin. The first layer may be primarily composed of one type of polyolefin resin, or may use two or more types of polyolefin resins. The resin component of the first layer may be polyolefin resin only.

[0015] The polyethylene resin of the first layer may be high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), or linear low-density polyethylene (LLDPE). The polyethylene resin of the first layer may be an ethylene homopolymer or a copolymer primarily composed of ethylene. The polypropylene resin of the first layer may be a propylene homopolymer or a copolymer primarily composed of propylene.

[0016] The first layer may be a stretched polyolefin resin film. The thickness of the first layer is not particularly limited, but is preferably from 10 μm to 50 μm, more preferably from 15 μm to 40 μm, and even more preferably from 20 μm to 35 μm.

[0017] (2nd layer) The second layer may be, for example, a sealant layer. The second layer may have a surface that comes into contact with contents such as liquids. The main component of the second layer is a polyolefin resin. The main component of the second layer may be a polyethylene resin or a polypropylene resin. The second layer may be primarily composed of one type of polyolefin resin, or may use two or more types of polyolefin resins. The resin component of the second layer may be polyolefin resin only.

[0018] The polyethylene resin of the second layer may be HDPE, MDPE, LDPE, LLDPE, etc. The polyethylene resin of the second layer may be an ethylene homopolymer or a copolymer mainly composed of ethylene. The polypropylene resin of the second layer may be a propylene homopolymer or a copolymer mainly composed of propylene.

[0019] The second layer may be a non-stretched polyolefin resin film. The thickness of the second layer is not particularly limited, but is preferably from 10 μm to 100 μm, more preferably from 30 μm to 80 μm.

[0020] (middle class) The intermediate layer is a resin layer laminated in contact with the first layer and the second layer. The main component of the intermediate layer is a polyolefin resin. The main component of the intermediate layer may be a polyethylene resin or a polypropylene resin. The intermediate layer may be mainly composed of one type of polyolefin resin, or may contain two or more types of polyolefin resins in combination. The resin component of the intermediate layer may be polyolefin resin only.

[0021] The polyethylene resin of the intermediate layer may be HDPE, MDPE, LDPE, LLDPE, etc. The polyethylene resin of the intermediate layer may be an ethylene homopolymer or a copolymer mainly composed of ethylene. The polypropylene resin of the intermediate layer may be a propylene homopolymer or a copolymer mainly composed of propylene.

[0022] In the laminate of the embodiment, the first layer, the second layer, and the intermediate layer are disposed directly adjacent to each other in the thickness direction of the laminate. The intermediate layer may be an extruded resin layer. In this case, the intermediate layer is formed by extruding a molten polyolefin resin between the first layer and the second layer. Whether the intermediate layer is formed by extrusion can be determined by observing the cross section of the laminate using, for example, a scanning electron microscope, and if bubbles are confirmed, it can be determined that the intermediate layer was formed by extrusion.

[0023] When the first and second layers are primarily composed of polypropylene resin, the intermediate layer is preferably primarily composed of polypropylene resin. When the first and second layers are primarily composed of polyethylene resin, the intermediate layer is preferably primarily composed of polyethylene resin. When a polyethylene resin is used for the intermediate layer, it is preferable to use either LLDPE or HDPE, or a mixed resin of LLDPE and HDPE.

[0024] The thickness of the intermediate layer is not particularly limited, but is preferably, for example, 10 μm or more and 100 μm or less, and more preferably 30 μm or more and 80 μm or less.

[0025] (Laminate) The laminate of the embodiment may be formed from a first layer, a second layer, and an intermediate layer. The laminate may have other resin layers in addition to the first layer, the second layer, and the intermediate layer. The other resin layers are preferably polyolefin resins such as polyethylene and polypropylene. By disposing the intermediate layer between the first and second layers without using an adhesive or anchor coating agent, the laminate can be easily recycled.

[0026] The polyolefin-based resin for the first layer, second layer, intermediate layer, etc. may be a polyolefin-based resin derived from fossil resources such as petroleum, a polyolefin-based resin derived from biomass such as plants, or a recycled polyolefin-based resin.

[0027] Each layer of the laminate may contain additives other than the resin as optional components. The additives are not particularly limited, but examples thereof include antioxidants, lubricants, antiblocking agents, flame retardants, UV absorbers, light stabilizers, antistatic agents, colorants, crosslinking agents, etc. The additives may be either components that are compatible with the resin or components that are not compatible with the resin.

[0028] The proportion of the polyolefin resin in the total amount of the laminate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. A high proportion of the polyolefin resin in the total amount of the laminate makes it easier to recycle it as a monomaterial.

[0029] In the laminate, the ratio of the thickness of the first layer (which serves as the base layer) to the thickness of the intermediate layer is preferably 1:1.6 or more and 2:2.8 or less. This allows for increased seal strength between the first and second layers without using adhesives made of different materials. The reason for this is not entirely clear, but it is thought that, for example, because the resin of the intermediate layer is weaker than the first layer (which serves as the base layer), interfacial damage may be suppressed by optimizing the thickness ratio between the two.

[0030] The ratio of the thickness of the second layer, which serves as the sealant layer, to the thickness of the intermediate layer is preferably 1:0.5 or more and 1:1.5 or less. This allows the seal strength between the first and second layers to be increased without using adhesives made of different materials. The reason for this is not entirely clear, but it is thought that, for example, since the resins of the second and intermediate layers have lower strength than the first layer, reducing the thickness difference between the second and intermediate layers may prevent interface failure.

[0031] Either the first layer or the second layer may have a printed surface. A printed layer is formed on the printed surface using ink or the like. The printed surface may be formed on the surface of the first or second layer facing the intermediate layer, or may be formed on the surface of the first layer opposite the side facing the intermediate layer. The printed layer may be formed on the outer surface of the laminate. When the first layer, second layer, and intermediate layer are arranged directly adjacent to each other in the thickness direction, the printed layer may be arranged between the first or second layer and the intermediate layer.

[0032] The printed layer can be formed by printing ink in a solid or patterned manner using a printing method such as gravure printing, letterpress printing, offset printing, screen printing, or inkjet printing. The thickness of the printed layer is not particularly limited, but may be about 0.5 to 10 μm. The printed layer may be formed over the entire surface of the laminate, or may be formed on a portion of the surface of the laminate. Two or more printed layers may be superimposed.

[0033] The ink for forming the printing layer may contain a coloring material such as a pigment or dye, and a binder. Examples of binders include, but are not limited to, polyamide, polyurethane, polyester, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, acrylic polymer, polybutadiene, and cyclized rubber. The ink may contain a solvent such as water, an organic solvent, or vegetable oil.

[0034] The laminate may optionally include a barrier layer. The barrier layer has barrier properties. Barrier properties refer to the ability to block external factors that can cause quality degradation. Examples of external factors that can cause quality degradation include water vapor, oxygen gas, organic compounds, and various other low-molecular-weight components. Two or more barrier layers having the same or different barrier properties may be laminated as the barrier layer. The material for forming the barrier layer is not particularly limited and may be appropriately selected from known barrier materials.

[0035] A barrier layer may be formed on the surface of the first layer facing the intermediate layer. A barrier layer may be formed on the surface of the first layer opposite to the surface facing the intermediate layer. A barrier layer may be laminated between the second layer and the intermediate layer. When the first layer or the second layer has a multilayer structure, the barrier layer may be provided in a portion of the first layer or a portion of the second layer. When the first layer, the second layer, and the intermediate layer are arranged directly adjacent to each other in the thickness direction, a barrier layer may be arranged between the first layer or the second layer and the intermediate layer.

[0036] The thickness of the barrier layer is preferably 5 μm or less. Specific examples of the thickness of the barrier layer are not particularly limited, but may be approximately 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, 0.5 μm, 0.2 μm, or 0.1 μm, or an intermediate value between these.

[0037] The barrier layer may be formed by vapor deposition of a metal such as aluminum, an inorganic compound such as silica or alumina, or diamond-like carbon (DLC). A metal foil may also be used as the barrier layer. A film formed from a barrier resin or a layer coated with a barrier coating agent may also be used as the barrier layer. The barrier coating agent can exhibit barrier properties by drying, curing, etc. Examples of the barrier material include polyvinylidene chloride, polyvinyl alcohol, and ethylene-vinyl alcohol copolymer (EVOH).

[0038] (Method of manufacturing laminate) 1 shows an example of an apparatus for producing a laminate 10 of an embodiment. The first layer 11 and the second layer 12 are transported in the form of a film, and the intermediate layer 13 is extruded as a molten resin film from an extrusion die 23 between the first layer 11 and the second layer 12. A roll member for guiding the films of the first layer 11 and the second layer 12 may be disposed below the extrusion die 23. For example, a nip roll 21 may be used for the first layer 11, and a cooling roll 22 may be used for the second layer 12, to press the first layer 11 and the second layer 12 against the intermediate layer 13.

[0039] At least one of the opposing surfaces of the first layer 11 or second layer 12 and the intermediate layer 13 may be subjected to a surface treatment, if necessary, to increase adhesive strength. Examples of surface treatments include oxidation treatments such as ozone treatment, and modification treatments using a specific atmospheric gas, such as electron beam irradiation treatment, low-pressure plasma treatment, atmospheric-pressure plasma treatment, and corona discharge treatment. The atmospheric gas used for the modification treatment may be an inert gas such as argon, helium, krypton, neon, xenon, or nitrogen, a reactive gas such as hydrogen or oxygen, or a mixed gas of two or more gases. The oxidation treatment may be a modification treatment performed in an oxidizing atmosphere. The surface treatment forms a surface-treated surface at the interface between the first layer 11 or second layer 12 and the intermediate layer 13, which has functional groups generated by oxidation, reduction, addition, elimination, or other reactions of the resin or the like.

[0040] The surface of the intermediate layer 13 extruded as a molten resin film, facing the first layer 11 or the second layer 12, may be surface-treated. This increases the adhesive strength, thereby increasing the sealing strength. The surface treatment for the intermediate layer 13 is not particularly limited, but examples include ozone treatment. It is also possible to perform surface treatment on both sides of the intermediate layer 13.

[0041] When the first layer 11 has a barrier layer, a coating layer, a printed layer, or the like on the surface facing the intermediate layer 13, the first layer 11 may be subjected to a surface treatment. When the second layer 12 has a barrier layer, a coating layer, a printed layer, or the like on the surface facing the intermediate layer 13, the second layer 12 may be subjected to a surface treatment. The surface treatment for the first layer 11 or the second layer 12 is not particularly limited, but examples thereof include electron beam irradiation treatment, low-pressure plasma treatment, atmospheric pressure plasma treatment, and corona discharge treatment.

[0042] (packaging bag) The laminate of the embodiment can be used as a material for a packaging bag. The contents of the packaging bag are not particularly limited, but examples thereof include liquids, solids such as powders and granules, viscous materials, liquids, and mixtures thereof. The types of contents are not particularly limited, but examples thereof include detergents, medicines, cosmetics, pharmaceuticals, beverages, seasonings, inks, paints, fuels, and the like.

[0043] The laminate of the embodiment is suitable for a packaging bag for packaging liquids. Specific examples of the packaging bag include, but are not limited to, a three-side sealed bag, a four-side sealed bag, a pillow bag, a gusset bag, a standing pouch, and the like.

[0044] When the packaging bag is a stand-up pouch, the packaging bag may include a body film and a bottom film. The body films are two films having the same planar shape as the packaging bag. The bottom film is folded in half and sandwiched between the lower part of the body film. The upper part of the body film may include a spout or a molded part such as a tube. When the packaging bag does not include a spout, an opening start portion such as a notch or an opening guide line such as a half cut may be provided so that the upper part of the body film can be torn and opened.

[0045] The dimensions of the packaging bag are not particularly limited. For example, in the case of use as a refill container, the vertical height is about 100 mm to 500 mm, the horizontal width is about 70 mm to 300 mm, and the filling amount is 100 cm 3 ~5000cm 3 The degree of

[0046] The present invention has been described above based on preferred embodiments, but the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. The laminate of the embodiment is not limited to packaging applications such as packaging bags and packaging films, but can be used for a variety of purposes. [Example]

[0047] The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

[0048] (Comparative Example 1) The first layer was a 25 μm-thick uniaxially oriented HDPE film, with a printed layer formed on one side. The printed layer was then subjected to atmospheric pressure plasma treatment under a nitrogen gas atmosphere. The second layer was a 90 μm-thick LLDPE film (density 0.927 g / cm). 3 The intermediate layer was LLDPE (density 0.898 g / cm 3 ) was melt-extruded to a thickness of 20 μm, and the surface of the intermediate layer facing the first layer was subjected to an oxidation treatment with ozone while the intermediate layer was laminated between the printed surface (plasma-treated surface) of the first layer and the second layer to produce a laminate of Comparative Example 1. The seal strength of the laminate of Comparative Example 1 was 56.4 N / 15 mm.

[0049] Example 1 Except for changing the thickness of the second layer to 70 μm and the thickness of the intermediate layer to 40 μm, the intermediate layer was laminated between the first layer and the second layer in the same manner as in Comparative Example 1, to produce the laminate of Example 1. The seal strength of the laminate of Example 1 was 89.1 N / 15 mm.

[0050] Example 2 Except for changing the thickness of the second layer to 50 μm and the thickness of the intermediate layer to 60 μm, the intermediate layer was laminated between the first layer and the second layer in the same manner as in Comparative Example 1, to produce a laminate of Example 2. The seal strength of the laminate of Example 1 was 87.6 N / 15 mm.

[0051] (Method for measuring seal strength) Two sheets of the laminate were prepared, and the second layers (sealant layers) were heat-sealed together (15 mm) using a TP-701-B heat seal tester (Tester Sangyo Co., Ltd.) to prepare a measurement sample. The heat sealing conditions were a temperature of 140°C, a pressure of 0.2 MPa, and a time of 1 second. The measurement sample was 15 mm wide. The measurement sample was subjected to an Autograph (registered trademark) AGS-X (Shimadzu Corporation) to observe the stress-strain curve. The strength at the time of sample breakage was taken as the seal strength. The measurement conditions were a chuck distance of 10 mm and a pulling speed of 300 mm / min.

[0052] (summary) The results of Comparative Example 1 and Examples 1 and 2 are shown in Table 1.

[0053] [Table 1]

[0054] By setting the ratio of the thickness of the first or second layer to the thickness of the intermediate layer within a predetermined range, the seal strength was improved. [Explanation of symbols]

[0055] 10... laminate, 11... first layer, 12... second layer, 13... intermediate layer, 21... nip roll, 22... cooling roll, 23... extrusion die.

Claims

1. A laminate having at least a first layer, a second layer, and an intermediate layer laminated in contact with the first layer and the second layer, the first layer, the second layer, and the intermediate layer are each primarily composed of a polyolefin resin; the first layer, the second layer, and the intermediate layer are disposed directly adjacent to each other in a thickness direction of the laminate; the first layer is a substrate layer and the second layer is a sealant layer; a ratio of a thickness of the first layer to a thickness of the intermediate layer is 1:1.6 or more and 2.8 or less; A laminate in which the ratio of the thickness of the second layer to the thickness of the intermediate layer is 1:0.5 or more and 1.5 or less.

2. The laminate according to claim 1 , wherein the polyolefin resin is at least one of a polyethylene resin and a polypropylene resin.

3. 3. The laminate according to claim 1, wherein at least one of the surfaces of the first layer or the second layer facing the intermediate layer is subjected to an oxidation treatment.

4. A packaging bag using the laminate according to any one of claims 1 to 3.

5. The packaging bag according to claim 4, which is for packaging liquids.

6. The packaging bag according to claim 5, which is a stand-up pouch.

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