Laminate, packaging bag, and standing pouch

Abstract

The present invention provides a laminate having, in addition to recyclability, drop strength, hand tearability, and processability, and also provides a packaging bag and a standing pouch formed from the laminate. More specifically, the present invention provides a laminate 10 comprising at least a first resin layer 11, a second resin layer 12, and a third resin layer 13 laminated in this order. The first resin layer 11 is an outermost layer made of a resin containing high-density polyethylene (HDPE). The second resin layer 12 is an intermediate layer made of a biaxially stretched vapor-deposited resin film containing linear low-density polyethylene (LLDPE). The third resin layer 13 is an innermost layer including a polyethylene-based sealant film.

Description

Laminated body, packaging bag, and standing pouch

[0001] The present invention relates to a laminated body, a packaging bag, and a standing pouch.

[0002] As a conventional packaging bag, a self-standing standing pouch in which a folded bottom member is disposed between a pair of body members is used. Paragraph 0010 of Patent Document 1 describes using a laminated film having a sealant as the innermost layer and a stretched film as a base material.

[0003] Japanese Unexamined Patent Publication No. 2006-007630

[0004] A composite film used for conventional packaging bags has a sealant film made of a heat-adhesive resin such as polyethylene (PE) on the inner surface, and a film made of polyethylene terephthalate (PET), nylon (Ny), or the like, which has higher heat resistance than the sealant film, is laminated as a base material on the outer surface. When thermally bonding the composite film, the sealant film is melted to bond the inner surfaces of the composite film. However, packaging bags containing different types of resins have a problem that they are difficult to recycle as plastic containers and packaging.

[0005] In recent years, in order to facilitate recycling, monomaterial containers and packaging using the same type of resin have been proposed. For example, the use of biaxially oriented polypropylene (BO-PP) as a base material is also described in Patent Document 1. However, compared to the combination of PET or Ny and PE, the combination of BO-PP and PE is less likely to achieve sufficient interlayer adhesion. For this reason, it is difficult to impart hand-tearability to the composite film.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laminated body that has recyclability as well as drop strength, hand-tearability, and processability, and a packaging bag and a standing pouch formed from the laminated body.

[0007] To solve the above problems, the present invention has the following configuration: [1] A laminate comprising at least a first resin layer, a second resin layer, and a third resin layer laminated in this order, wherein the first resin layer is the outermost layer made of a resin containing high-density polyethylene (HDPE), the second resin layer is an intermediate layer made of a biaxially oriented vapor-deposited resin film containing linear low-density polyethylene (LLDPE), and the third resin layer is the innermost layer containing a polyethylene-based sealant film. [2] The laminate according to [1], wherein the first resin layer is a stretched resin film. [3] A packaging bag in which at least one component is formed from the laminate according to [1] or [2]. [4] The packaging bag according to [3] for the purpose of enclosing liquid. [5] A standing pouch in which the body film is formed from the laminate according to [1] or [2].

[0008] According to the present invention, it is possible to provide a laminate that, in addition to recyclability, possesses drop strength, tearability, and processability, as well as packaging bags and standing pouches formed from the laminate.

[0009] This is a cross-sectional view illustrating an example of the laminate of the embodiment. This is a plan view illustrating a standing pouch.

[0010] The present invention will be described below based on preferred embodiments.

[0011] The laminate 10 of the embodiment shown in Figure 1 has a first resin layer 11 as the outermost layer, a second resin layer 12 as an intermediate layer, and a third resin layer 13 as the innermost layer. Since the first resin layer 11, the second resin layer 12, and the third resin layer 13 all contain polyethylene-based resin, the laminate 10 can be made of a monomaterial. In this specification, "outermost layer" means the outermost layer that comes into contact with the outside when a packaging bag and standing pouch are formed from the laminate, and "innermost layer" means the layer located on the opposite side of the laminate from the outermost layer, and the inner layer that comes into contact with the contents when a packaging bag and standing pouch are formed from the laminate. Furthermore, "intermediate layer" means the layer located between the outermost layer and the innermost layer, but it does not necessarily have to be in contact with the outermost layer or the innermost layer.

[0012] The first resin layer 11 is the outermost layer made of a resin containing high-density polyethylene (HDPE). By using high-density HDPE on the outermost surface of the laminate 10, the heat resistance of the laminate 10 can be improved. This is advantageous for processes that apply heat to the laminate 10, such as dry lamination and heat sealing. From the viewpoint of improving tearability by hand, the first resin layer 11 is preferably a stretched resin film. In this case, the first resin layer 11 may be a uniaxially oriented film or a biaxially oriented film.

[0013] The first resin layer 11 can also be composed of a composite (multilayer structure or blended resin) of high-density polyethylene (HDPE) and a dissimilar resin such as polypropylene (PP) or ethylene-vinyl alcohol copolymer (EVOH), depending on the application. Here, the dissimilar resin refers to a resin other than polyethylene-based resins.

[0014] The second resin layer 12 is an intermediate layer made of a biaxially oriented vapor-deposited resin film containing linear low-density polyethylene (LLDPE). By using flexible LLDPE in the intermediate layer of the laminate 10, the impact resistance of the laminate 10 can be improved. Furthermore, by using a biaxially oriented film in the intermediate layer, durability against tearing and other forces can be provided. When a biaxially oriented film is used in the intermediate layer, tear resistance in the intended direction is improved compared to a uniaxially oriented film or an unoriented film.

[0015] The second resin layer 12 can also be composed of a composite (multilayer structure or blended resin) of linear low-density polyethylene (LLDPE) and a different resin such as polypropylene (PP) or ethylene-vinyl alcohol copolymer (EVOH), depending on the application. Here, the different resin refers to a resin other than polyethylene-based resins.

[0016] Furthermore, in the case of uniaxially oriented films, tearing in the stretching direction may occur, potentially reducing durability. Also, if an unoriented film is used as the intermediate layer, the strength may be lower compared to an oriented film.

[0017] The stretching direction of the biaxially oriented film in the second resin layer 12 is not particularly limited, but it may be stretched in the transport (MD) direction and the cross (TD) direction. Furthermore, the stretching ratio of the biaxially oriented film is preferably within the range of 2 to 10 times in both the MD direction and the TD direction. The stretching ratio in the MD direction and the stretching ratio in the TD direction may be equal to or different from each other.

[0018] LLDPE generally reduces the density of polyethylene by copolymerizing monomers with 4 to 8 carbon atoms (such as α-olefins). HDPE generally has fewer branches and higher crystallinity, resulting in relatively higher strength among polyethylene resins. HDPE is not limited to ethylene homopolymers; for example, copolymers obtained by copolymerizing α-olefins to include short branches may also be used.

[0019] The third resin layer 13 is a sealant resin layer containing a polyethylene-based sealant film. The sealant resin layer can be used to join the laminate 10 by heat sealing.

[0020] Examples of resins used in the third resin layer 13 include relatively low-density polyethylene resins such as linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE), or unstretched polyethylene resins. The third resin layer 13 may be formed from one type of resin, or it may be a composite of two or more resins (multilayer structure or blended resin). At least a part of the material forming the third resin layer 13 may be, for example, an amorphous resin or an acid-modified resin.

[0021] The third resin layer 13 may be a multilayer sealant film. A multilayer sealant film can be formed by laminating two or more resin layers by co-extrusion or the like. The multilayer sealant film may have two or more polyethylene-based resin layers. Furthermore, the multilayer sealant film may include a resin layer made of ethylene-vinyl alcohol copolymer (EVOH). Examples of layer configurations for sealant films containing PE and EVOH include PE / EVOH / PE (innermost layer), EVOH / PE (innermost layer), and the like.

[0022] To impart barrier properties to the laminate 10, the second resin layer 12 may be coated with vapor deposition. Furthermore, the outermost first resin layer 11 may be coated with vapor deposition or EVOH. The vapor deposition or EVOH may be formed on either the inner or outer surface of the first resin layer 11 or the second resin layer 12. Examples of vapor deposition materials used for the vapor deposition layer include metals such as aluminum, and metal oxides such as silica and alumina. When a metal such as aluminum is vapor-deposited, an opaque metal vapor-deposited film is obtained. When a metal oxide such as silica or alumina is used, a transparent vapor-deposited film is obtained.

[0023] Furthermore, by applying a coating agent between the vapor-deposited layer and the first resin layer 11 or the second resin layer 12, the adhesion between the resin layer and the vapor-deposited layer, as well as the barrier properties of the laminate 10, can be improved. Additionally, by forming a vapor-deposited layer on the outside of the first resin layer (the outermost layer of the laminate 10) and applying a coating agent to the outside of that layer, the abrasion resistance, heat resistance, and barrier properties of the laminate 10 can also be improved.

[0024] The polyethylene resin may be a homopolymer of ethylene or a copolymer mainly composed of ethylene. Examples of monomers other than ethylene (comonomers) include 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.

[0025] Polyethylene resins can be made from recycled materials as well as virgin materials, and biomass resins can be made from petroleum-derived synthetic resins as well. Recycled materials can be recycled chemically or materially. Biomass resins can be derived from plants, animals, or various other sources such as food products.

[0026] EVOH can be obtained by saponifying a copolymer containing ethylene and a vinyl ester monomer, converting at least a portion of the vinyl ester units into vinyl alcohol units. Examples of the vinyl ester monomer include vinyl carboxylates such as vinyl formate, vinyl acetate, vinyl butyrate, and vinyl benzoate. The ethylene content of EVOH can be, for example, 20 to 60 mol%. The degree of saponification of EVOH is not limited to 100 mol%, but is preferably, for example, 80 mol% or more.

[0027] The additives that may be included in each of the above-mentioned resin layers are not particularly limited, but examples include antioxidants, lubricants, antiblocking agents, flame retardants, ultraviolet absorbers, light stabilizers, antistatic agents, colorants, crosslinking agents, and compatibilizers. The additives may be components that are compatible with the resin or components that are not compatible with the resin.

[0028] In the laminate 10 of this embodiment, the sealant film of the third resin layer 13 is poor at tearing by hand on its own, but because a biaxially oriented vapor-deposited resin film is adjacent to it as the second resin layer 12, the third resin layer 13 becomes more likely to tear in accordance with the rupture of the second resin layer 12 when torn, thereby improving the tearability of the laminate 10 by hand.

[0029] The thickness of each layer in the laminate 10 is not particularly limited, but the thickness of the first resin layer 11 may be, for example, about 10 to 50 μm. The thickness of the second resin layer 12 may be, for example, about 10 to 50 μm. The thickness of the third resin layer 13, which serves as a sealant, may be, for example, about 60 to 180 μm. If the sealant is multilayered, the thickness may be the sum of the thicknesses of each layer.

[0030] An adhesive layer 14 may be interposed between the first resin layer 11 and the second resin layer 12. An adhesive layer 15 may also be interposed between the second resin layer 12 and the third resin layer 13. The adhesive layers 14 and 15 may be formed from an adhesive, an anchor coating agent, or an extruded resin.

[0031] The materials used to form the adhesive layers 14 and 15 are not particularly limited, but in the case of adhesives and anchor coating agents, examples include urethane compounds, epoxy compounds, isocyanate compounds, polyethyleneimine, and organic titanium compounds such as titanium alkoxide. In the case of extruded resins, examples include polyolefin resins.

[0032] The thickness of the adhesive layers 14 and 15 can be, for example, 0.1 to 10 μm, 1 to 6 μm, or 3 to 4 μm in the case of adhesives or anchor coating agents, and 5 to 100 μm in the case of extruded resins.

[0033] Although not specifically shown in the figures, the laminate 10 may have a printed layer. The printed layer may be formed on one or more surfaces selected from the outer surface of the first resin layer 11, the inner surface of the first resin layer 11, the outer surface of the second resin layer 12, the inner surface of the second resin layer 12, etc.

[0034] The total weight of the polyethylene resin contained in the laminate 10 is preferably 80% by weight or more, and more preferably 90% by weight or more, relative to the weight of the laminate 10. This makes it possible to achieve recyclability, drop strength, tearability, and processability equivalent to that of a laminate formed using a single-material polyethylene resin, even if different resins, vapor-deposited layers, coating agents, additives, adhesives, anchor coating agents, printing inks, etc., are used in the laminate 10.

[0035] 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 suitable for use in refilling a main container used when consuming the contents, 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.

[0036] The laminate 10 may have a portion for opening or cutting the packaging bag. Specific examples include structures processed in the thickness direction of the film, such as perforations, notches, or half-cut grooves; shapes that suggest opening or cutting within the film surface, such as a thinly protruding spout; and markings such as arrows, lines, or dots printed on the surface. Cutting the packaging bag is not limited to cutting the opening portion; it 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 where tags or markings are continuously attached around the packaging bag.

[0037] For processing such as perforations, notches, and half-cut grooves, there are no particular limitations, and processing with cutting tools or lasers can be used. In a configuration in which the vapor-deposited layer is laminated on the resin film of the laminate 10, the laser reacts easily, so a laser can be preferably used.

[0038] 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 illustrated 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. The packaging bag 100 has a body seal portion 104 to which the front and rear body members 101 are joined to each other, and a bottom seal portion 105 to which the bottom member 102 is joined to the body members 101.

[0039] The dimensions of the packaging bag 100 are not particularly limited, but for example, when used as a refillable container, the height in the vertical direction is about 100 to 500 mm, the width in the horizontal direction is about 70 to 300 mm, and the filling volume is about 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 examples include detergents, chemicals, cosmetics, pharmaceuticals, beverages, seasonings, inks, paints, fuels, etc.

[0040] The laminate 10 of the embodiment is in the form of a laminated film mainly composed of a polyethylene-based resin, and is not limited to packaging bags such as pouches, bags and containers, and packaging laminates such as packaging films, and can be used for various applications. When the laminate 10 is a flexible laminated film, it can form a flexible packaging bag 100. The packaging bag 100 may be formed only of the laminate 10, or may be combined with accessory members such as labels, tags, straws, and outer boxes. From the viewpoint of recycling, it is preferable that the accessory members can be separated from the packaging bag 100.

[0041] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0042] A laminate (the leftmost end is the outermost layer, and the rightmost end is the innermost layer) having the configuration shown below was produced. As for the types of resins, Ny means nylon, PET means polyethylene terephthalate, LLDPE means linear low-density polyethylene, HDPE means high-density polyethylene, and PE means polyethylene. Regarding the symbols attached before the symbols representing the types of resins, BO- means biaxially stretching, MDO- means uniaxially stretching, VM- means vapor deposition (metal or metal oxide), and EVOH- means ethylene-vinyl alcohol copolymer coating. " / / " between layers means a dry lamination adhesive layer, and " / barrier AD / " means an adhesive layer having barrier properties.

[0043] ・Comparative Example 1: Ny 15 μm / / PET 12 μm / / LLDPE sealant 130 μm ・Comparative Example 2: MDO-HDPE 25 μm / / VM-BO-HDPE 25 μm / / LLDPE sealant 90 μm ・Comparative Example 3: MDO-HDPE 25 μm / / VM-LLDPE 25 μm / / MDO-PE 25 μm / / LLDPE sealant 90 μm ・Comparative Example 4: BO-LLDPE 25 μm / / VM-BO-LLDPE 25 μm / / LLDPE sealant 90 μm ・Example 1: MDO-HDPE 25 μm / / VM-BO-LLDPE 25 μm / / LLDPE sealant 90 μm ・Example 2: BO-HDPE 25 μm / / VM-BO-LLDPE 25 μm / / LLDPE sealant 90 μm ・Example 3: EVOH-MDO-HDPE 25 μm / / VM-BO-LLDPE 25 μm / / LLDPE sealant 90 μm ・Example 4: MDO-HDPE 25 μm / barrier AD / VM-BO-LLDPE 25 μm / / LLDPE sealant 90 μm ・Example 5: MDO-HDPE 25 μm / / VM-BO-LLDPE 25 μm / / EVOH-LLDPE sealant 90 μm ・Example 6: VM-MDO-HDPE 25 μm / / VM-BO-LLDPE 25 μm / / LLDPE sealant 90 μm

[0044] The recyclability of the laminate was evaluated as good (○) when all films contained in the target laminate are polyethylene-based resins, and poor (×) when other resins are contained.

[0045] For the drop strength of the laminate, a standing pouch with a width of 130 mm, a height of 220 mm, and a bottom folding width of 35 mm produced from the target laminate was filled with 330 ml of water. For each pouch, dropping vertically 5 times from a height of 1 m, then dropping horizontally 5 times, and this procedure was repeated for 30 pouches. Evaluation was given as good (○) when none of the 30 pouches broke, and poor (×) when one or more of the 30 pouches broke.

[0046] For the hand-tearability of the laminate, a half-cut line penetrating the first resin layer was formed by laser on a packaging bag produced from the target laminate, and then the laminate was torn by hand. Evaluation was given as good (○) when the packaging bag could be opened by hand, and poor (×) when it could not be opened by hand.

[0047] The processability of the laminate was assessed by determining the difference between the melting point of the resin used in the outermost layer and the melting point of the resin used in the innermost layer of the laminate. A melting point difference of 40°C or more was evaluated as excellent (◎), a difference of 20°C or more but less than 40°C was evaluated as good (○), and a melting point difference of less than 20°C was evaluated as poor (×).

[0048] For fragrance retention, a predetermined amount of the contents (conditioner) was filled into a four-sided sealed bag made from the target laminate, sealed in an aluminum bag, and left for one week in an environment of 23°C and 50% RH. The smell inside the aluminum bag was then checked. It was evaluated as good (○) if no fragrance from the contents could be detected, acceptable (△) if the smell was weak, and unacceptable (×) if the smell was strong.

[0049] Water vapor transmission rate (WVTR) is measured using the target laminate in accordance with the infrared sensor method of JIS K7129, under conditions of 40°C and 100% RH (g / m³). ２ ・24 hours.

[0050] Oxygen permeability (OTR) is measured using the target laminate in accordance with the isobaric method of JIS K7126, under conditions of 30°C and 70% RH (cm³). ３ / m ２ ・24 hours.

[0051]

[0052] The laminates of Examples 1 to 6 possess not only recyclability but also drop strength, tearability, and processability. Furthermore, the laminates of Examples 3 to 6 exhibit improved aroma retention compared to the laminates of Examples 1 and 2. The laminate of Comparative Example 1 has poor recyclability because it uses Ny and PET. The laminate of Comparative Example 2 has poor drop strength because it uses HDPE in the intermediate layer. The laminate of Comparative Example 3 has poor drop strength and tearability because it uses MDO-PE in the layer adjacent to the sealant and unstretched VM-LLDPE in the vapor-deposited film. The laminate of Comparative Example 4 has poor processability because it uses LLDPE in the outermost layer.

[0053] 10...Laminate, 11...First resin layer, 12...Second resin layer, 13...Third resin layer, 14, 15...Adhesive layer, 100...Packaging bag, 101...Body member, 102...Bottom member, 103...Fold line, 104...Body seal part, 105...Bottom seal part.

Claims

At least, a laminate comprising a first resin layer, a second resin layer, and a third resin layer stacked in this order, The first resin layer is the outermost layer made of a resin containing high-density polyethylene (HDPE), The second resin layer is an intermediate layer consisting of a biaxially oriented vapor-deposited resin film containing linear low-density polyethylene (LLDPE), The laminate is characterized in that the third resin layer is the innermost layer containing a polyethylene-based sealant film. 　 The laminate according to claim 1, characterized in that the first resin layer is a stretched resin film. 　 A packaging bag characterized in that at least one component is formed from the laminate described in claim 1 or 2. 　 The packaging bag according to claim 3, characterized in that it is used for sealing liquids. 　 A standing pouch characterized in that the body film is formed from the laminate described in claim 1 or 2.

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