Laminates and packaging bags

Abstract

To provide a laminate and a packaging bag which can obtain sufficient hand tearability in addition to recyclability.SOLUTION: A laminate 10 has at least a C4LLDPE layer and a biaxially oriented polypropylene-based resin layer adjacent to the C4LLDPE layer, wherein films 11, 12 and 13 included in the laminate 10 are composed of only a polypropylene-based resin or a polyethylene-based resin.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a conventional packaging bag, a standing pouch having self-standing property in which a bottom member folded in two is disposed between a pair of body members is used. Paragraph 0010 of Patent Document ́1 describes using 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

Summary of the Invention

Problems to be Solved by the Invention

[0004] The composite film used for conventional packaging bags has a heat-sealing resin (sealant) layer such as polyethylene (PE) on the inner surface, and a base material such as polyethylene terephthalate (PET) or nylon (Ny) having higher heat resistance than the sealant is laminated on the outer surface. When heat-sealing the composite film, the sealant is melted and the inner surface of the composite film is joined. However, there is a problem that it is difficult to recycle a packaging bag containing different resins as a plastic container package.

[0005] In recent years, in order to facilitate recycling, a mono-material container package using a single or the same kind of resin has been proposed. For example, using biaxially stretched polypropylene (BO-PP) as the base material is also described in Patent Document ́1. However, the combination of BO-PP and PE is less likely to obtain interlayer adhesion than the combination of PET or Ny and PE. Therefore, it is difficult to impart tearability to the composite film.

[0006] This invention has been made in view of the above circumstances, and aims to provide a laminate and packaging bag that are recyclable and also sufficiently easy to tear by hand. [Means for solving the problem]

[0007] The present invention includes the following embodiments. A first aspect of the present invention is a laminate having at least a C4LLDPE layer and a biaxially oriented polypropylene resin layer adjacent to the C4LLDPE layer, characterized in that the film included in the laminate consists only of a polypropylene resin or a polyethylene resin.

[0008] A second aspect of the present invention is a laminate according to the first aspect, characterized in that the C4LLDPE layer is the innermost layer that serves as a sealant for the laminate. A third aspect of the present invention is a laminate according to the second aspect, characterized in that the thickness of the innermost layer, which is made of the C4LLDPE layer, is 80 μm or more. A fourth aspect of the present invention is a laminate according to any one of the first to third aspects, characterized in that the biaxially oriented polypropylene resin layer adjacent to the C4LLDPE layer has an aluminum vapor deposition treatment layer on the side opposite to the C4LLDPE layer.

[0009] A fifth aspect of the present invention is a packaging bag characterized in that at least one component is formed from a laminate of any one of the first to fourth aspects. A sixth aspect of the present invention is a packaging bag according to the fifth aspect, characterized in that it is a standing pouch. A seventh aspect of the present invention is a packaging bag according to the fifth or sixth aspect, characterized in that it is used for sealing liquids. An eighth aspect of the present invention is a packaging bag according to any one of the fifth to seventh aspects, characterized in that it is for refilling purposes. A ninth aspect of the present invention is a packaging bag according to any one of the fifth to eighth aspects, characterized in that it is provided with an opening guide line by a laser half-cut. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide laminates and packaging bags that offer sufficient tearability in addition to recyclability. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view illustrating an example of the laminate of the embodiment. [Figure 2] This is a plan view illustrating a standing pouch. [Modes for carrying out the invention]

[0012] The present invention will be described below based on preferred embodiments.

[0013] In the embodiment shown in Figure 1, the laminate 10 contains films 11, 12, and 13 made solely of polyolefin resin. Examples of polyolefin resins include polypropylene resin or polyethylene resin.

[0014] The laminate 10 comprises at least a C4LLDPE layer and a biaxially oriented polypropylene resin layer adjacent to the C4LLDPE layer. Of the films 11, 12, and 13, at least one layer is the C4LLDPE layer. Furthermore, of the films 11, 12, and 13, at least one of the layers adjacent to the C4LLDPE layer is the biaxially oriented polypropylene resin layer.

[0015] The laminate 10 in the illustrated example has an innermost layer 11, an intermediate layer 12, and an outer layer 13 as films 11, 12, and 13. The innermost layer 11, which acts as a sealant for the laminate 10, is a C4LLDPE layer. The intermediate layer 12 adjacent to the innermost layer 11 is a biaxially oriented polypropylene resin layer. The outer layer 13 is a polypropylene resin layer or a polyethylene resin layer.

[0016] The laminated body 10 in the figure example has three layers of films 11, 12, and 13, but the number of layers of the films (resin layers) included in the laminated body 10 is not particularly limited, and it may be two layers, three layers, or four or more layers.

[0017] The C4LLDPE layer is a polyethylene-based resin layer containing linear low-density polyethylene (LLDPE) copolymerized with a C4 monomer. Examples of the monomer having 4 carbon atoms (C4) include 1-butene. Generally, LLDPE reduces the density of polyethylene by copolymerizing monomers having 4 to 8 carbon atoms (C4 to C8).

[0018] The C6 and C8 monomers have longer chains than the C4 monomer, and the strength of polyethylene tends to be higher. C4LLDPE copolymerized with a C4 monomer can obtain a resin with lower strength compared to C6LLDPE and C8LLDPE copolymerized with C6 and C8 monomers.

[0019] The proportion of C4LLDPE in the total weight of the C4LLDPE layer or the entire resin component is preferably 51% by weight or more, more preferably 80% by weight or more, and may be 100% by weight. The C4LLDPE layer may contain other polyethylene-based resins or resin components, and may also contain additives other than the resin components.

[0020] The biaxially stretched polypropylene-based resin layer is a layer of biaxially stretched polypropylene-based resin (BO-PP). The polyethylene-based resin layer of the outer layer 13 may be a C4LLDPE layer or a polyethylene-based resin layer other than C4LLDPE. The polypropylene-based resin layer of the outer layer 13 may be a biaxially stretched polypropylene-based resin layer or other polypropylene-based resin layers.

[0021] The proportion of the polyethylene-based resin in the total weight of the polyethylene-based resin layers included in the laminated body 10 or the entire resin component is preferably 80% by weight or more, more preferably 90% by weight or more, and may be 100% by weight. The polyethylene-based resin layer may contain other resin components, and may also contain additives other than the resin components.

[0022] The total weight of the polypropylene resin layer in the laminate 10, or the proportion of polypropylene resin in the total resin components, is preferably 80% by weight or more, more preferably 90% by weight or more, and may be 100% by weight. The polypropylene resin layer may contain other resin components, and may also contain additives other than resin components.

[0023] In the laminate of this embodiment, the C4LLDPE layer and the biaxially oriented polypropylene resin layer are laminated in adjacent positions. This improves the tearability when polyethylene is laminated adjacent to biaxially oriented polypropylene. Furthermore, since the films 11, 12, and 13 included in the laminate 10 consist only of polypropylene resin or polyethylene resin, recyclability can be improved compared to cases where PET or Ny is used as the base material.

[0024] In the illustrated example, the intermediate layer 12 is joined adjacent to the innermost layer 11 via an adhesive layer 14 by dry lamination or the like. Although not specifically shown, the intermediate layer 12 may also be adjacent to the innermost layer 11 without the adhesive layer 14 by co-extrusion, heat lamination, or the like.

[0025] The laminate 10 may omit the outer layer 13, or it may have two or more outer layers 13. In the illustrated example, the outer layer 13 is joined adjacent to the intermediate layer 12 via an adhesive layer 15. Although not specifically shown, the outer layer 13 may be adjacent to the intermediate layer 12 without an adhesive layer 15. The lamination of the outer layer 13 may be done via an adhesive layer by dry lamination or the like, or the adhesive layer may be omitted by co-extrusion, thermal lamination or the like.

[0026] Although not specifically shown in the diagram, the C4LLDPE layer may be placed in the intermediate layer 12 instead of the innermost layer 11. In this case, the biaxially oriented polypropylene resin layer is placed in at least one of the innermost layer 11 or the outer layer 13.

[0027] Since the laminate 10 of this embodiment has excellent tearability, the thickness of the C4LLDPE layer may be relatively thick. For example, the thickness of the innermost layer 11, which is made of C4LLDPE, can be 80 μm or more.

[0028] The intermediate layer 12 adjacent to the innermost layer 11 is a biaxially oriented polypropylene resin layer, which provides sufficient strength and improves flexibility, impact resistance, etc. The stretching direction and stretching ratio in biaxial stretching are not particularly limited, but stretching may be performed in the transport (MD) direction and the cross (TD) direction. The stretching ratio is preferably within the range of 2 to 10 times in both the MD and TD directions. The stretching ratio in the MD direction and the stretching ratio in the TD direction may be equal to each other or different.

[0029] To impart barrier properties to the laminate 10 of the embodiment, a thin film of a metal such as aluminum, or an inorganic compound such as silica or alumina may be laminated. For example, a barrier layer 16 made of the above-mentioned metal or inorganic compound may be formed on at least one side of any of the films 11, 12, or 13 by vapor deposition, plating, or the like.

[0030] From the viewpoint of interlayer adhesion between the C4LLDPE layer and the biaxially oriented polypropylene resin layer, it is preferable not to form a barrier layer between the C4LLDPE layer and the biaxially oriented polypropylene resin layer, but to form barrier layers between other layers. For example, it is preferable to form a barrier layer, such as an aluminum vapor deposition layer, on the side of the biaxially oriented polypropylene resin layer adjacent to the C4LLDPE layer that is opposite to the C4LLDPE layer. In the laminate 10 of the illustrated example, the C4LLDPE layer is the innermost layer 11, the biaxially oriented polypropylene resin layer is the intermediate layer 12, and the barrier layer 16 is formed on the side of the intermediate layer 12 that faces the outer layer 13.

[0031] The laminate 10 is a resin film mainly composed of polyolefin resin (polypropylene resin or polyethylene resin), but various designs are possible in addition to those described above.

[0032] Polyethylene resins may be homopolymers of ethylene or copolymers mainly composed of ethylene. Examples of monomers other than ethylene (comonomers) include one or more α-olefins such as 1-butene, 1-hexene, and 1-octene, cyclic olefins such as norbornene, and vinyl monomers such as vinyl acetate, vinyl chloride, and acrylic acid. When polyethylene resins are copolymerized with monomers having ester groups such as vinyl acetate, some of the ester groups may be saponified, resulting in a copolymer containing vinyl alcohol.

[0033] The proportion of ethylene in the constituent monomers of the polyethylene resin is preferably 50% by weight or more, and may be, for example, 80 to 100% by weight. The ethylene or comonomer may be a compound derived from fossil resources such as petroleum, or a compound derived from biomass such as plants. The resin contained in the polyethylene resin layer may consist solely of polyethylene resin. At least a portion of the polyethylene resin may also contain recycled polyethylene resin.

[0034] The polypropylene resin mentioned above may be a homopolymer of propylene (homoPP), or a random copolymer (randomPP) or block copolymer (blockPP) of propylene-ethylene copolymer, etc. Examples of monomers other than propylene (comonomers) include one or more α-olefins such as ethylene, 1-butene, 1-hexene, and 1-octene, and vinyl monomers such as vinyl acetate, vinyl chloride, and acrylic acid. When comonomers are used in the polypropylene resin, there may be one or more comonomers.

[0035] The proportion of propylene in the constituent monomers of the polypropylene resin is preferably 50% by weight or more, and may be, for example, 80 to 100% by weight. The propylene or comonomer may be a compound derived from fossil resources such as petroleum, or a compound derived from biomass such as plants. The resin contained in the polypropylene resin layer may consist only of polypropylene resin. At least a portion of the polypropylene resin may also contain recycled polypropylene resin.

[0036] The films 11, 12, and 13 contained in the laminate 10 may contain additives other than resin. The additives are not particularly limited, but examples include antioxidants, lubricants, antiblocking agents, flame retardants, UV absorbers, light stabilizers, antistatic agents, colorants, and crosslinking agents. The additives may be components compatible with the resin or components incompatible with the resin.

[0037] The innermost layer 11 can be used to join the laminate 10. The innermost layer 11 is preferably formed from an unstretched polyolefin resin. Specific examples of materials for forming the innermost layer 11 include, for example, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and polypropylene resins. The material forming the innermost layer 11 may be a single type of polyolefin resin or a blend of two or more types of polyolefin resins. The thickness of the innermost layer 11 is not particularly limited, but for example, it may be about 60 to 180 μm.

[0038] The intermediate layer 12 or the outer layer 13 may be the base material of the laminate 10. Specific examples of materials forming the intermediate layer 12 or the outer layer 13 include, for example, linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polypropylene resins. The material forming the intermediate layer 12 may be a single polyolefin resin or a blend of two or more polyolefin resins. The thickness of the intermediate layer 12 is not particularly limited, but for example, it may be about 10 to 50 μm.

[0039] The proportion of the innermost layer 11 to the thickness of the laminate 10 is preferably 50% or more, and may be around 60%, 70%, 80%, 90%, 95%, or an intermediate value therein. The proportion of the total thickness of the polyolefin resin films 11, 12, and 13 to the thickness of the laminate 10 is preferably 50% or more, and may be around 60%, 70%, 80%, 90%, 95%, 99%, or an intermediate value therein.

[0040] Each of the films 11, 12, and 13 contained in the laminate 10 may be joined via an adhesive layer by dry lamination or the like, or they may be joined without an adhesive layer by co-extrusion, thermal lamination or the like.

[0041] The adhesive layers 14 and 15 may be formed from an adhesive or from an anchor coating agent. The material used to form the adhesive layers 14 and 15 is not particularly limited, but examples include urethane compounds, epoxy compounds, isocyanate compounds, polyethyleneimine, and organotitanium compounds such as titanium alkoxide. The thickness of the adhesive layers 14 and 15 using adhesives or anchor coating agents can be, for example, about 0.1 to 10 μm, about 1 to 6 μm, or about 3 to 4 μm.

[0042] The adhesive layers 14 and 15 may be formed from an extruded resin. The material of the extruded resin is not particularly limited, but examples include adhesive resins and polyolefin resins. The thickness of the adhesive layers 14 and 15 using the extruded resin can be approximately 3 to 30 μm, 5 to 25 μm, or 7 to 20 μm.

[0043] The laminate 10 may have a printed layer (not shown). For example, a printed layer may be laminated on the inner or outer surface of the outer layer 13. The printed layer can be formed by printing ink in a solid or patterned manner using printing methods such as gravure printing, letterpress printing, offset printing, screen printing, or inkjet printing. The thickness of the printed layer is not particularly limited, but is typically around 0.5 to 10 μm. The printed layer may be formed over the entire surface of the laminate or on a part of the surface of the laminate. Two or more printed layers may be stacked on top of each other.

[0044] The ink used to form the printed layer may contain a coloring agent such as a pigment or dye, and a binder. The binder is not particularly limited, but examples include polyamide, polyurethane, polyester, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, acrylic polymer, polybutadiene, and cyclocompound rubber. The ink may also contain a solvent such as water, organic solvent, or vegetable oil. After printing, the ink can be dried by the evaporation of the solvent or curing of the ink. Heating or ultraviolet irradiation may be used to accelerate the drying of the ink.

[0045] For monomaterial containers and packaging made of polyolefin resin (polypropylene resin or polyethylene resin), it is preferable that the total weight of the polyolefin resin is 80% or more by weight of the total weight of the laminate 10, and the total weight of materials other than polyolefin resin is 20% or less by weight, and more preferably that the total weight of the polyolefin resin is 90% or more by weight, and the total weight of materials other than polyolefin resin is 10% or less by weight. This makes it possible to realize a monomaterial material of polyolefin resin even if adhesives or the like are used in the laminate 10.

[0046] The laminate 10 can be used to manufacture packaging bags. The packaging bag only needs to have at least one component made from the laminate 10. The use of the packaging bag is not particularly limited, and can be for disposable use, refilling, storage, or storing goods, but it is particularly suitable for use in refilling a main container used when consuming the contents, either once or multiple times. In this case, the main container can be made durable for long-term use, and the packaging of the refill container can be simplified. In addition, recycling becomes easier when disposing of the refill container after the contents have been used up.

[0047] The laminate 10 may have a portion for opening or cutting the packaging bag. The portion for opening or cutting may have a structure processed in the thickness direction of the film, such as a perforation, notch, or half-cut groove, or it may have a shape that suggests opening or cutting within the surface of the film, such as a thinly protruding spout, or it may be an indication such as an arrow, line, or dot printed on it. Cutting the packaging bag is not limited to cutting the opening portion, but may also be used to cut between or around packaging bags in areas where two or more packaging bags are formed in a continuous manner, or in areas where tags or display portions are continuous around the packaging bag.

[0048] Specific examples of packaging bags are not limited to three-sided sealed bags, four-sided sealed bags, pillow bags, flat bags, gusset bags, and standing pouches. Figure 2 shows an example of a packaging bag 100. The packaging bag 100 is a standing pouch formed from a pair of body members 101 and a bottom member 102 that is folded in half along a fold line 103.

[0049] The packaging bag 100 has two body members 101, one at the front and one at the back. The planar shapes of the front and back body members 101 may be the same. The bottom member 102 is folded in along a fold line 103 so that its outer surfaces face each other. Above the fold line 103, body seal portions 104 are formed on the left and right sides, and the inner surfaces of the front and back body members 101 are joined together.

[0050] The bottom member 102 is sandwiched between the front and rear body members 101 with the fold line 103 facing upwards. Below the fold line 103, a bottom seal portion 105 is formed where the inner surface of the bottom member 102 is joined to the inner surface of the body member 101. The bottom seal portion 105 joins the area of ​​the bottom member 102 demarcated by the fold line 103 to the body member 101 on the same side in the front-to-back direction. By spreading the bottom member 102 relative to the fold line 103, the packaging bag 100 can be made to stand on its own.

[0051] If the packaging bag 100 has a body member 101 and a bottom member 102, the laminate 10 of the embodiment may be used for either the body member 101 or the bottom member 102, or for both. From the viewpoint of improving tearability, it is preferable to use the laminate 10 for the body member 101. It is also suitable for packaging bags 100 used to enclose liquids.

[0052] The dimensions of packaging bag 100 are not particularly limited, but for example, when used as a refillable container, the height in the vertical direction is approximately 100-500 mm, the width in the horizontal direction is approximately 70-300 mm, and the filling volume is approximately 100 cm. 3 ~5000cm 3 The degree can be mentioned. The state of the contents can be fluids such as liquids, powders, or granules, or solids such as articles. The type of contents is not particularly limited, but can be detergents, chemicals, cosmetics, pharmaceuticals, beverages, seasonings, inks, paints, fuels, etc.

[0053] The packaging bag 100 may have a filling opening, a spout, etc. For example, the top of the packaging bag 100 may be open between the front and rear body members 101, allowing it to be used for filling or dispensing contents. After filling with contents, the body members 101 may be joined together to seal the packaging bag 100. When opening the packaging bag 100, the area where the body members 101 were joined can be easily torn. Although not specifically shown, the spout may be formed as a thin projection at the top or corner of the packaging bag 100. The spout may be made of film or be of the spout type. When a spout is installed diagonally at a corner, biaxial stretching is advantageous in terms of drop strength, etc.

[0054] The method for recycling the laminate 10 or packaging bag 100 of the embodiment after use is not particularly limited, but can be appropriately selected depending on the condition at the time of collection, etc. Since the laminate 10 of the embodiment can have a high proportion of polyolefin resin, both chemical recycling and mechanical recycling are possible. By recycling the laminate 10 or packaging bag 100 of the embodiment, it is also possible to regenerate similar products such as the laminate 10 or packaging bag 100. The recycled material may be used in products such as paints, molded products, and hydrocarbon oils.

[0055] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. Modifications include the addition, substitution, omission, and other changes to the components.

[0056] The laminate 10 of the embodiment is a laminated film mainly composed of polyolefin resin and is not limited to packaging laminates such as pouches, bags, containers, and packaging films, but can be used for various applications. If the laminate 10 is a flexible laminated film, a flexible packaging bag 100 can be formed. The packaging bag 100 may be formed from the laminate 10 alone, or it may be combined with auxiliary components such as labels, tags, straws, and outer boxes. From a recycling standpoint, it is preferable that the auxiliary components can be separated from the packaging bag 100. [Examples]

[0057] The present invention will be described in more detail below as examples, but it is not limited to these examples.

[0058] <Fabrication of laminates> In Example 1, a laminate was fabricated by laminating a film with a layer configuration of BO-PP 20 μm / VM-BO-PP 18 μm / C4LLDPE 100 μm. Comparative Example 1 involved laminating a film with a layer configuration of Ny 15 μm / VM-PET 12 μm / C6 LLDPE 120 μm to create a laminate. Comparative Example 2 involved laminating a film with a layer configuration of BO-PP 20 μm / VM-BO-PP 18 μm / C6LLDPE 100 μm to create a laminate.

[0059] In the above layer configuration, PP represents polypropylene, PET represents polyethylene terephthalate, Ny represents nylon, BO- represents biaxially oriented, and VM- represents aluminum vapor deposition.

[0060] <Evaluation of recyclability> The recyclability of the laminate was evaluated as good (○) if the laminate contained only PP or PE films, and poor (×) if it contained films other than PP or PE.

[0061] <Evaluation of the ability to end a relationship quickly> The ease of tearing the laminate by hand was evaluated by making a half-cut line with a laser on a refill pouch using the laminate as the main body component, and then tearing the opening by hand. If it could be opened (○), it was evaluated as not being able to be opened (×).

[0062] <Evaluation of tear strength> The tear strength (N) was measured using the Elmendorf method in the MD direction with two layers of the target laminate stacked together.

[0063] <Evaluation of Lamination Strength> Laminate strength (N / 25mm) was measured by preparing a 25mm wide sample of the target laminate and measuring the delamination strength between the innermost layer and adjacent layers at a speed of 5mm / min in the MD direction using the ring method (90-degree delamination).

[0064] <Evaluation Results> The evaluation results for Example 1 were: recyclability: ○, tearability by hand: ○, tear strength: 14N, and lamination strength: 5.7N / 25mm (substrate cohesive failure). The evaluation results for Comparative Example 1 were: recyclability: ×, tearability by hand: ○, tear strength: 14N, and lamination strength: 13.9N / 25mm (substrate cohesive failure). The evaluation results for Comparative Example 2 were: recyclability: ○, tearability by hand: ×, tear strength: 25N, and lamination strength: 5.2N / 25mm (substrate cohesive failure). [Explanation of Symbols]

[0065] 10...Laminate, 11...Innermost layer, 12...Intermediate layer, 13...Outer layer, 14,15...Adhesive layer, 16...Barrier layer, 100...Packaging bag, 101...Body member, 102...Bottom member, 103...Fold line, 104...Body seal part, 105...Bottom seal part.

Claims

1. A laminate comprising at least a C4LLDPE layer and a biaxially oriented polypropylene resin layer adjacent to the C4LLDPE layer, wherein the film included in the laminate consists solely of a polypropylene resin or a polyethylene resin. The C4LLDPE layer is the innermost single layer that serves as a sealant for the laminate. The thickness of the innermost layer, which is made of the C4LLDPE layer, is 80 μm or more. The laminate is characterized in that the biaxially oriented polypropylene resin layer is adjacent to the innermost layer via an adhesive layer by dry lamination.

2. The laminate according to claim 1, characterized in that the biaxially oriented polypropylene resin layer adjacent to the C4LLDPE layer has an aluminum vapor-deposited layer on the side opposite to the C4LLDPE layer.

3. A packaging bag characterized in that at least one component is formed from the laminate described in claim 1 or 2.

4. The packaging bag according to claim 3, characterized in that it is a standing pouch.

5. The packaging bag according to claim 3, characterized in that it is used for sealing liquids.

6. The packaging bag according to claim 3, characterized in that it is for refilling purposes.

7. The packaging bag according to claim 3, characterized in that it is provided with an opening guide line made by a laser half-cut.

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