Laminates for packaging bags, packaging bags, packaging bags with spouts, and packaging bags with spouts containing contents

Abstract

To provide a laminate for a packaging bag which is easily recyclable and can stably produce a packaging bag and to provide a packaging bag and a packaging bag with a spout using the laminate for a packaging bag.SOLUTION: There is provided a laminate for a packaging bag 1 used for a packaging bag, a packaging bag with a spout and a packaging bag with a spout containing contents, which is obtained by laminating a base material layer 10, an intermediate layer 20 and a sealant layer 30 in this order, wherein the base material layer 10 is a stretched film made of polypropylene, the intermediate layer 20 is a multilayer coextruded film in which support layers 22, 23 mainly composed of polyolefin are laminated on both sides of a gas barrier resin layer 21 and the sealant layer 30 is a film made of one or more selected from a homopolymer or a copolymer of ethylene.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate for a packaging bag, a packaging bag, a packaging bag with a spout, and a packaging bag with a spout containing contents.

Background Art

[0002] Conventionally, for packaging bags that contain fluid contents such as liquids like soft drinks and juices, ice cream, jelly, cosmetics, shampoo, rinse, liquid soap, or pasty substances, laminates that are a composite combination of plastic films and metal foils have been used for the purpose of imparting storage stability and strength to withstand distribution. It is practically difficult to separate such a laminate composed of a combination of multiple materials, and it is not suitable for material recycling, and is thermally recycled.

[0003] In recent years, due to the need for global environmental protection, there has been a growing trend towards shifting from thermal recycling to material recycling. Therefore, monomaterial laminates composed of a combination of single materials, rather than laminates composed of a combination of different materials, have come to attract attention. Patent Document 1 proposes a laminate for a packaging bag with a spout in which a base material subjected to at least one of stretching treatment and electron beam irradiation treatment and a sealant layer are made of the same material of polyethylene or polypropylene.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the laminate for packaging bags described in Patent Document 1, although material recycling is easy, the base material and the sealant layer are made of the same material, so their melting points are close. This can cause problems due to thermal shrinkage during the bag-making process in manufacturing packaging bags, and improvements were desired to ensure stable production of packaging bags.

[0006] The present invention aims to provide a laminate for packaging bags that facilitates material recycling and enables the stable manufacture of packaging bags, a packaging bag using the laminate for packaging bags, and a packaging bag with a spout. [Means for solving the problem]

[0007] The present invention includes the following configuration. [1] A laminate for packaging bags in which a base layer, an intermediate layer, and a sealant layer are laminated in this order, The aforementioned substrate layer is a stretched film made of polypropylene. The intermediate layer is a multilayer co-extruded film comprising a gas barrier resin layer and support layers mainly composed of polyolefin laminated on both sides of the gas barrier resin layer. The sealant layer is a film made of one or more homopolymers or copolymers of ethylene, in a laminate for packaging bags. [2] The laminate for packaging bags according to [1], wherein the gas barrier resin layer contains an ethylene-vinyl alcohol copolymer. [3] The laminate for packaging bags according to [2], wherein the ethylene unit content of the ethylene-vinyl alcohol copolymer is 20 mol% or more and 70 mol% or less. [4] The laminate for packaging bags according to any one of [1] to [3], wherein the polyolefin monomaterial content of the multilayer co-extruded film is 75% or more by mass. A packaging bag made of a laminate for packaging bags as described in any of [5][1] to [4]. A spouted packaging bag, which is the packaging bag described in [6][5] with a spout attached. [7] The spout packaging bag according to [6], wherein the spout includes a gas barrier layer. A spouted packaging bag containing contents, wherein the contents are contained in the spouted packaging bag described in [8], [6], or [7]. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a laminate for packaging bags that facilitates material recycling and enables the stable manufacture of packaging bags, packaging bags using the laminate for packaging bags, and packaging bags with spouts. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a laminate for a packaging bag, representing an example of an embodiment. [Figure 2] This is a cross-sectional view showing another example of a laminated structure with an intermediate layer. [Figure 3] This is a front view showing a spouted packaging bag, an example of an embodiment. [Figure 4] This is a front view showing an example of a spout. [Figure 5] This is a schematic cross-sectional view showing an example of a spout with gas barrier properties. [Modes for carrying out the invention]

[0010] An example of an embodiment of the present invention will be described below. The embodiments described below are merely examples of how the present invention may be implemented, and the present invention is not limited to the specific configurations described below. In implementing the present invention, specific configurations may be adopted as appropriate depending on the embodiment. Furthermore, the dimensions and other details shown in the diagrams exemplified in the following description are merely examples, and the present invention is not necessarily limited to them. It can be implemented with appropriate modifications without altering its essence.

[0011] [Laminated body for packaging bags] As shown in Figure 1, the laminated packaging bag 1 of this embodiment is made of plastic film, and the base layer 10, the intermediate layer 20, and the sealant layer 30 are laminated in this order. In the packaging bag using the laminate 1 for packaging bags, the base material layer 10 forms the outer surface of the packaging bag, and the sealant layer 30 having heat-sealability forms the inner surface of the packaging bag. Further, the intermediate layer 20 is a layer provided between the base material layer 10 and the sealant layer 30.

[0012] In an example shown in FIG. 1, in the laminate 1 for packaging bags, the base material layer 10 and the intermediate layer 20 are laminated via an adhesive layer 41, and the intermediate layer 20 and the sealant layer 30 are laminated via an adhesive layer 42. That is, the laminate 1 for packaging bags has a laminated structure laminated in the order of the base material layer 10, the adhesive layer 41, the intermediate layer 20, the adhesive layer 42, and the sealant layer 30. In the following description, the laminated structure of the example shown in FIG. 1 is also shown as "base material layer 10 / adhesive layer 41 / intermediate layer 20 / adhesive layer 42 / sealant layer 30", and other laminated structures are shown in the same manner.

[0013] (Base material layer) The base material layer 10 is composed of a stretched film made of polypropylene (hereinafter, also referred to as "stretched PP film"). By the stretching treatment, the strength as a film such as tensile strength and rigidity is improved. In particular, by improving the rigidity, the elongation when tension (tension) or heat acts on the base material layer 10 is suppressed, so that the processing suitability such as printing suitability and bag-making suitability becomes more excellent.

[0014] The stretching treatment includes uniaxial stretching in which the film is stretched in either the longitudinal direction or the transverse direction in the film manufacturing process, and biaxial stretching in which the film is stretched in both the longitudinal direction and the transverse direction in the film manufacturing process. The stretching treatment in the stretched PP film used for the base material layer 10 may be either uniaxial stretching or biaxial stretching. Further, in the case of biaxial stretching, it may be sequential biaxial stretching or simultaneous biaxial stretching. In addition, known additives such as stabilizers, antioxidants, lubricants, antistatic agents, or colorants may be added to the stretched PP film used for the base material layer 10.

[0015] From the viewpoint of improving productivity, the thickness of the base layer 10 is preferably 10 μm or more, and more preferably 20 μm or more. From the viewpoint of improving processability, the thickness of the base layer 10 is preferably 70 μm or less, and more preferably 60 μm or less. The lower and upper limits of the thickness of the base layer 10 can be arbitrarily combined, for example, 10 to 70 μm is preferred.

[0016] Preferably, the melting point of the base layer 10 is at least higher than the melting point of the sealant layer 30. Because the melting point of the base layer 10 is higher than that of the sealant layer 30, the sealant layer 30 melts before the base layer 10 during the bag-making process or spout attachment process using a heat-sealing device. Therefore, it is possible to manufacture high-quality packaging bags and spouted packaging bags with excellent compressive strength and impact resistance, without curling or wrinkling caused by thermal shrinkage of each sealed portion. Specifically, the melting point of the base layer 10 is preferably 155 to 175°C. The difference between the melting point of the base layer 10 and the melting point of the sealant layer 30 is preferably 20°C to 85°C.

[0017] (Ink layer) An ink layer may be provided on the outside or inside of the base material layer 10, as needed. Methods for forming the ink layer include gravure printing, offset printing, and flexographic printing. Among these printing methods, gravure printing is preferred because it offers superior color reproduction. The ink layer is formed by printing letters, figures, decorations, and management codes related to the contents. If opacity is required, for example, a gray opacity ink layer can be provided to prevent the color of the contents from showing through when the contents are filled into the packaging bag. This opacity ink layer can be any color that can conceal the contents, not just gray. Furthermore, two or more opacity ink layers may be provided as needed.

[0018] (Middle class) The intermediate layer 20 is composed of a multilayer co-extruded film (hereinafter also referred to as "multilayer co-extruded film (A)") which includes a gas barrier resin layer and support layers mainly composed of polyolefin laminated on both sides of the gas barrier resin layer. In other words, the intermediate layer 20 is composed of an unstretched film with support layers laminated on both sides of the gas barrier resin layer. However, "mainly composed of polyolefin" in the support layers means that the content ratio of polyolefin to the total mass of the support layers is 50% by mass or more. An adhesive resin layer may be provided between the support layer and the gas barrier resin layer.

[0019] In one example shown in Figure 1, the intermediate layer 20 is composed of a multilayer co-extruded film (A) with a laminated structure of support layer 22 / adhesive resin layer 24 / gas barrier resin layer 21 / adhesive resin layer 25 / support layer 23. Note that the multilayer co-extruded film (A) constituting the intermediate layer 20 is not limited to the five-layer structure shown in Figure 1; for example, it may have a three-layer structure of support layer 22 / gas barrier resin layer 21 / support layer 23 as shown in Figure 2.

[0020] As mentioned above, stretching a plastic film improves its strength, such as tensile strength and rigidity, but on the other hand, it reduces its flexibility, thus impairing its shock absorption properties. A laminate for packaging bags using a multilayer co-extruded film (A), which is an unstretched film, as the intermediate layer 20 has superior shock absorption compared to a laminate for packaging bags using a stretched film as the intermediate layer 20. Therefore, the laminate for packaging bags of the present invention has the effect of dispersing the stress when instantaneous stress, such as a drop impact, acts on the laminate for packaging bags, and has excellent impact resistance. Furthermore, the laminate for packaging bags of the present invention also has high compressive strength because a multilayer co-extruded film (A) is used as the intermediate layer 20.

[0021] The gas barrier resin layer 21 functions as a layer that blocks gases, mainly oxygen, that permeate the laminate 1 for the packaging bag. Examples of materials constituting the gas barrier resin layer 21 include ethylene-vinyl alcohol copolymer (EVOH), vinyl alcohol polymer (PVA), and polyamide using metaxylenediamine. Among these, EVOH is preferred as the material constituting the gas barrier resin layer 21 from the viewpoint of processability, gas barrier properties, and versatility. The gas barrier resin layer 21 may consist of one material or two or more materials.

[0022] EVOH is a polymer obtained by saponification of an ethylene-vinyl acetate copolymer. Since the oxygen permeability of EVOH is lower than that of polyethylene, the gas barrier resin layer 21 using EVOH functions mainly as a layer that suppresses the permeation of gases such as oxygen. The lower the ethylene unit content of EVOH, the closer its structure is to PVA, allowing for molecular cohesive forces through hydrogen bonding, resulting in superior oxygen barrier properties. Note that "ethylene units" refer to repeating units derived from ethylene in the polymer.

[0023] The ethylene unit content of EVOH is preferably 20 mol% or more, and more preferably 25 mol% or more, relative to the total units of EVOH. When the ethylene unit content is 20 mol% or more, thermal stability is good, moldability is excellent, foreign matter such as gel is less likely to be generated in extrusion melt molding, and the film tends to be less likely to tear in stretch molding. The ethylene unit content of EVOH is preferably 70 mol% or less, and more preferably 50 mol% or less. When the ethylene unit content is 70 mol% or less, sufficient gas barrier properties tend to be easily obtained. The lower and upper limits of the ethylene unit content of EVOH can be arbitrarily combined, for example, 20 to 70 mol% is preferred, and 25 to 50 mol% is more preferred. Specific examples of EVOH include the product names "Eval" manufactured by Kuraray and "Soanol" manufactured by Mitsubishi Chemical.

[0024] From the viewpoint of improving gas barrier properties such as oxygen, the thickness of the gas barrier resin layer 21 is preferably 3 μm or more, and more preferably 4 μm or more. From the viewpoint of material recyclability, the thickness of the gas barrier resin layer 21 is preferably 30 μm or less, and more preferably 20 μm or less. The lower and upper limits of the thickness of the gas barrier resin layer 21 can be arbitrarily combined, for example, 3 to 30 μm is preferred.

[0025] Examples of polyolefins constituting the support layers 22 and 23 include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE, density: 0.940~0.970 g / cm³). 3 Examples include linear low-density polyethylene (LLDPE) and polypropylene. Polypropylene (density: 0.890~0.910 g / cm³) 3 This includes homopolypropylene, random polypropylene, and block polypropylene. Among these, HDPE or polypropylene, which have high melting points, are preferred for the support layers 22 and 23. The polyolefin constituting the support layers 22 and 23 may be one type or two or more types.

[0026] Using HDPE or polypropylene for the support layers 22 and 23 results in higher heat resistance and rigidity compared to, for example, using LLDPE for the support layers 22 and 23. This suppresses dimensional changes in the packaging bag laminate 1 due to the effects of heat and tension during bag making, thus reducing problems such as pattern misalignment during bag making. Furthermore, using HDPE or polypropylene for the support layers 22 and 23 exhibits superior water vapor barrier properties compared to using polyethylene other than HDPE. Therefore, moisture contained in the contents is prevented from permeating and being lost to the outside of the packaging bag during storage, allowing the quality of the contents to be maintained in a better state for a longer period. In addition, the gas barrier resin layer 21 can be protected from steam even when the packaging bag using the packaging bag laminate 1 is boiled.

[0027] Support layers 22 and 23 may contain resins other than polyolefins. Examples of resins other than polyolefins include elastomers such as ethylene-1-butene random copolymers and ethylene-propylene random copolymers. If support layers 22 and 23 contain resins other than polyolefins, there may be one type of resin or two or more types of resins other than polyolefins. Furthermore, known additives such as stabilizers, antioxidants, lubricants, antistatic agents, or colorants may be added to the support layers 22 and 23.

[0028] The polyolefin content in the support layer 22 is 50% by mass or more, preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total mass of the support layer 22. If the polyolefin content is above the lower limit, material recycling becomes easier. The upper limit of the polyolefin content in the support layer 22 is not particularly limited and can be, for example, 100% by mass. The polyolefin content in the support layer 23 is the same as the polyolefin content in the support layer 22. The polyolefin content in the support layer 23 and the polyolefin content in the support layer 22 may be the same or different, but it is preferable that they be the same.

[0029] From the viewpoint of improving productivity, the thickness of the support layer 22 is preferably 10 μm or more, and more preferably 20 μm or more. From the viewpoint of improving processability, the thickness of the support layer 22 is preferably 50 μm or less, and more preferably 40 μm or less. The lower and upper limits of the thickness of the support layer 22 can be arbitrarily combined, for example, 10 to 50 μm is preferred. The thickness of the support layer 23 is the same as the thickness of the support layer 22. The thickness of the support layer 23 and the thickness of the support layer 22 may be the same or different, but it is preferable that they be the same.

[0030] As the adhesive resin constituting the adhesive resin layers 24 and 25, polyolefin-based adhesive resins are preferred, which are obtained by chemically bonding monobasic unsaturated fatty acids, ester compounds of monobasic unsaturated fatty acids, anhydrous dibasic fatty acids, etc., to ethylene-based resins or propylene-based resins. Examples of ethylene-based resins include LLDPE, LDPE, and ethylene-vinyl acetate copolymer (EVA). Examples of propylene-based resins include propylene homopolymers and copolymers of propylene with other α-olefins. Examples of monobasic unsaturated fatty acids include acrylic acid and methacrylic acid. Examples of ester compounds of monobasic unsaturated fatty acids include methyl acrylate, methyl methacrylate, and glycidyl methacrylate. Examples of anhydrides of dibasic fatty acids include anhydrides such as maleic acid, fumaric acid, and itaconic acid. Specific examples of adhesive resins include "Admer," a product name manufactured by Mitsui Chemicals, and "Modic," a product name manufactured by Mitsubishi Chemical. The adhesive resins constituting the adhesive resin layers 24 and 25 may consist of one type or two or more types.

[0031] The thickness of the adhesive resin layer 24 is preferably 1 to 10 μm, and more preferably 3 to 7 μm. The thickness of the adhesive resin layer 25 is the same as the thickness of the adhesive resin layer 24. The thicknesses of the adhesive resin layer 25 and the adhesive resin layer 24 may be the same or different, but it is preferable that they be the same.

[0032] From the viewpoint of material recyclability, the polyolefin monomaterial ratio of the intermediate layer 20, that is, the polyolefin monomaterial ratio of the multilayer co-extruded film (A), is preferably 75% or more by mass, and more preferably 80% or more by mass. However, "monomaterial ratio" refers to the mass ratio of a single material to the total mass. The "polyolefin monomaterial ratio of the intermediate layer" is the proportion of olefin by mass in the multilayer co-extruded film (A) (resin material) used for the intermediate layer.

[0033] From the perspective of improving productivity, the thickness of the intermediate layer 20 is preferably 25 μm or more, and more preferably 50 μm or more. From the perspective of improving processability, the thickness of the intermediate layer 20 is preferably 150 μm or less, and more preferably 114 μm or less. The lower and upper limits of the thickness of the intermediate layer 20 can be arbitrarily combined, for example, 25 to 150 μm is preferred.

[0034] The sealant layer 30 is a layer made of a film consisting of one or more homopolymers or copolymers of ethylene. Examples of monomers copolymerizable with ethylene include α-olefins other than ethylene, such as propylene, 1-butene, 1-hexene, and 1-octene, as well as vinyl esters such as vinyl acetate, acrylic acid, methacrylic acid, methyl methacrylate, and methyl acrylate. The content of α-olefin units in the ethylene copolymer is preferably 2 to 10 mol%, and more preferably 4 to 6 mol%, relative to the total units of the ethylene copolymer. Furthermore, the content of vinyl ester units in the ethylene copolymer is preferably 2 to 12 mol%, and more preferably 4 to 10 mol%, relative to the total units of the ethylene copolymer.

[0035] Examples of sealant layers 30 include unstretched films made from one or more materials selected from the group consisting of LDPE, MDPE, LLDPE, HDPE, ionomer resin, EVA, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl acrylate copolymer, and ethylene-methacrylic acid copolymer. The unstretched film constituting the sealant layer 30 may be a single-layer film or a multi-layer film. The sealant layer 30 may contain known additives, such as stabilizers, antioxidants, lubricants, antistatic agents, or colorants.

[0036] From the viewpoint of improving productivity, the thickness of the sealant layer 30 is preferably 20 μm or more, and more preferably 30 μm or more. From the viewpoint of improving processability, the thickness of the sealant layer 30 is preferably 200 μm or less, and more preferably 150 μm or less. The lower and upper limits of the thickness of the sealant layer 30 can be arbitrarily combined, for example, 20 to 200 μm is preferred. The melting point of the sealant layer 30 is preferably 90 to 135°C.

[0037] The adhesive layers 41 and 42 can be formed by dry lamination, non-solvent lamination, or extrusion lamination, which involves extruding molten polyethylene from a T-die into a film and laminating it. Of these methods, dry lamination is the most preferred method for forming the adhesive layers 41 and 42, from the viewpoint of adhesive strength between the base layer 10 and the intermediate layer 20, and adhesive strength between the intermediate layer 20 and the sealant layer 30.

[0038] The thickness of the adhesive layer 41 is preferably 2 to 20 μm. The thickness of the adhesive layer 42 is the same as the thickness of the adhesive layer 41. The thicknesses of the adhesive layer 42 and the adhesive layer 41 may be the same or different, but it is preferable that they be the same.

[0039] From the standpoint of material recyclability, the higher the polyolefin monomaterial content of the laminated packaging bag 1, the better, with 80% or more being preferable. A high polyolefin monomaterial content means that there is less residue during material recycling, enabling efficient recycling.

[0040] [Packaging bags, spouted packaging bags, spouted packaging bags with contents] The packaging bag of the present invention is composed of a laminate for packaging bags of the present invention. The structure of the packaging bag is not particularly limited as long as it can contain the contents in a liquid-tight manner and a spout, as described later, can be attached to it. For example, the packaging bag can be a side-gusset bag with a gusset on the side, a bottom-gusset bag (standing bag) with a gusset on the bottom, a square-bottom bag with gussets on the side and bottom, a pillow bag, or a flat bag with a laminate for packaging bags sealed on three or four sides. A bag-making machine is used to manufacture the packaging bags. The sealing method for each part of the bag-making machine can be heat sealing, impulse sealing, or ultrasonic sealing, among others.

[0041] In the packaging bag of the present invention, the base layer is a stretched PP film, and the sealant layer is a film made of one or more homopolymers or copolymers of ethylene. Because a laminate for packaging bags is used in which the difference between the melting points of the base layer and the sealant layer is sufficiently large, problems due to thermal shrinkage are less likely to occur during the bag manufacturing process. Furthermore, because a multilayer co-extruded film (A), which is an unstretched film, is deliberately used as the intermediate layer of the laminate for packaging bags, the laminate for packaging bags itself absorbs the stress when instantaneous stress such as impact from dropping is applied to the packaging bag. As a result, the stress on the seal portion at the periphery of the packaging bag is reduced, and problems such as the packaging bag bursting due to instantaneous stress can be suppressed.

[0042] The contents to be contained in the packaging bag are not particularly limited as long as they are fluid, and examples include liquids such as soft drinks and juices, ice cream, jelly, cosmetics, shampoo, conditioner, liquid soap, and other fluid or paste-like substances. The packaging bag is preferably designed to hold a weight of, for example, 30g to 1500g.

[0043] The spouted packaging bag of the present invention is a packaging bag of the present invention to which a spout is attached, and comprises a packaging bag for containing contents and a spout fixed to the packaging bag. For example, one example is a spouted packaging bag 100 as shown in Figure 3. The spouted packaging bag 100 comprises a packaging bag 110 and a spout 120. The spout 120 comprises a spout body 121 and a cap 122, with the spout body 121 attached to the top of the packaging bag 110. The spout body 121 allows the contents to pass through, and the cap 122 closes the opening at the tip of the spout body 121.

[0044] The packaging bag 110 in the example shown in Figure 3 is a side-gusset bag. That is, the packaging bag 110 is constructed by sandwiching two side films 113 and 114, which are folded in half at the fold V, between a front film 111 and a rear film 112 that overlaps the front film 111. The laminate for packaging bags of the present invention can be used as the front film 111, the rear film 112, and the side films 113 and 114. For example, the laminate for packaging bags 1 can be used as the front film 111, the rear film 112, and the side films 113 and 114.

[0045] The front film 111, rear film 112, and side films 113 and 114, which are overlapped at the lower end of the packaging bag 110, are bonded to each other by a bottom seal 110a. The ends of the front film 111 on both sides of the packaging bag 110 and the ends of the side films 113 and 114 that overlap the ends of the front film 111 are bonded to each other by side seals 110b and 110c. Similarly, the ends of the rear film 112 on both sides of the packaging bag 110 and the ends of the side films 113 and 114 that overlap the ends of the rear film 112 are bonded to each other by side seals (not shown). As a result, the side portions of the packaging bag 110 are formed by the side films 113 and 114 bonded between the front film 111 and the rear film 112.

[0046] At the upper end of the packaging bag 110, an upper seal 110d is formed that adheres the front film 111, the rear film 112, and the side films 113 and 114 to each other, with a spout 120 sandwiched in the center in the width direction. The spouted packaging bag of the present invention is not limited to the spouted packaging bag 100.

[0047] Spouted packaging bags can be manufactured by inserting a spout into the opening of a packaging bag produced by a bag-making machine and then attaching the spout to the packaging bag using a spout attachment machine. The spout attachment method in the spout attachment machine can include heat sealing, impulse sealing, or ultrasonic sealing.

[0048] The polyolefin monomaterial content of the packaging bag is preferable as high as possible, and preferably 80% or more. Similarly, the polyolefin monomaterial content of the spouted packaging bag is preferable as high as possible, and preferably 90% or more. The polyolefin monomaterial ratio for packaging bags refers to the proportion of olefin by mass among the materials used in the packaging bag. Similarly, the polyolefin monomaterial ratio for spouted packaging bags refers to the proportion of polyolefin by mass among the materials used in the spouted packaging bag. In other words, the polyolefin monomaterial ratio for spouted packaging bags includes the spout itself.

[0049] If the polyolefin monomaterial content of the spout-equipped packaging bag of the present invention is set to 90% or more, it will be possible to satisfy the guideline of "a polyolefin content of 90% or more in flexible packaging containers," which is preferred by CEFLEX (Circular Economy for Flexible Packaging), a consortium (joint venture) in Europe that aims to realize a circular economy in the flexible packaging field, and it will be possible to provide flexible packaging containers that are easy to recycle.

[0050] (Spout) The spout will be described in detail below. The spout 120 shown in Figures 3 and 4 is an example and comprises a spout body 121 and a cap 122. The spout body 121 has a cylindrical dispensing section 123 formed at its upper part, with one end having an opening 123a, and a long, slender cylindrical straw section 124. Between the dispensing section 123 and the straw section 124, there are two tiered bases 125 that extend horizontally outward from the outer circumference of the dispensing section 123. In addition, the straw section 124 below the lower base 125 is provided with an attachment section 126 that is adhered to the upper end of the packaging bag 110.

[0051] The straw portion 124, formed at the lower part of the spout body 121, is shaped like an elongated cylinder and is inserted into the packaging bag 110. This straw portion 124 has an opening at its lower end. The mounting portion 126 is formed to protrude to the left and right along the width direction of the packaging bag. The upper end of the packaging bag 110 is adhered to the outer surface of this mounting portion 126, and a liquid-tight bond is formed between the two by a heat sealing means or the like to prevent any gap from forming.

[0052] The dispensing portion 123, located at the top of the spout body 121, is formed in a cylindrical shape, and a spiral male thread 127 is formed on its outer surface. This male thread 127 engages with a female thread formed on the cap 122, allowing the cap 122 to be screwed onto the dispensing portion 123. In this way, the cap 122 can be detachably attached to the dispensing portion 123, and the dispensing portion 123 can be closed.

[0053] The cap 122 consists of a cylindrical cap body 128 and a band 129 that extends outward from the outer circumference of the cap body 128 at the lower end of the cap body 128 and extends in the circumferential direction of the cap 122.

[0054] The cap body 128 is formed in a cylindrical shape capable of covering the dispensing portion 123, with one end along the central axis, the upper surface, being closed and the other end, the lower surface, being open. Furthermore, the cap body 128 has a spiral female thread formed on its inner circumference, and is configured to be screwed into the male thread 127 formed on the outer circumference of the dispensing portion 123. On the inner side of the upper surface of the cap body 128, a cylindrical sealing body is formed radially inward from the inner circumferential surface and protrudes downward. When the cap is screwed onto the dispensing portion, this sealing body tightly seals the inner circumferential surface of the dispensing portion 123 against the outer surface of the sealing body, preventing the contents from leaking out.

[0055] From the viewpoint of material recyclability, polyethylene is preferred as the material constituting the spout body 121 and cap 122 of the spout 120. Examples of polyethylene materials that make up the spout body 121 and cap 122 include LDPE, MDPE, HDPE, and LLDPE, with HDPE being particularly preferred from the viewpoint of strength and other factors. The spout 120 can be formed by known molding methods such as injection molding and compression molding.

[0056] From the viewpoint of gas barrier properties, it is preferable that the spout includes a gas barrier layer. More specifically, it is preferable that the spout body includes a gas barrier layer. For example, in the spout body 121 shown in Figure 5, a cylindrical body 130 is housed inside, which has a laminated structure consisting of an outer layer 131, an adhesive layer (not shown), a gas barrier layer 132, an adhesive layer (not shown), and an inner layer 133, in that order from the outside. By housing such a cylindrical body 130 inside the spout body 121, gas barrier properties can be imparted to the spout 120.

[0057] Because the spout body 121 has gas barrier properties, it is possible to prevent deterioration of the contents, such as oxidation, during storage, as well as changes in the concentration and weight of the contents caused by the evaporation of moisture contained in the contents. In particular, when the packaging bag contains highly viscous liquid contents, the contents may remain in the dispensing part 123. Even in such cases, because the spout body 121 has gas barrier properties, oxidation and browning of the contents remaining in the dispensing part 123 can be prevented.

[0058] Examples of materials constituting the gas barrier layer 132 include polyamides using EVOH, PVA, and metaxylenediamine. Among these, EVOH is preferred as the material constituting the gas barrier layer 132 from the viewpoint of processability, gas barrier properties, and versatility. The gas barrier layer 132 may consist of one material or two or more materials.

[0059] From the viewpoint of material recyclability, polyethylene is preferred as the material constituting the outer layer 131 and the inner layer 133. Examples of polyethylene constituting the outer layer 131 and the inner layer 133 include LDPE, MDPE, HDPE, and LLDPE, with HDPE being preferred from the viewpoint of water vapor permeability and rigidity. By selecting HDPE, the water vapor permeability of the cylindrical body 130 is reduced, thereby suppressing a decrease in the gas barrier properties of the gas barrier layer 132 due to the influence of moisture contained in the contents and moisture contained in the outside air. The material constituting the outer layer 131 and the inner layer 133 may be one type or two or more types.

[0060] In the cylindrical body 130, the thickness of the inner layer 133 must be at least the thickest of the layers forming the cylindrical body 130. If the inner layer 133 is thick, the water vapor permeability of the inner layer 133 will be low, and the gas barrier layer 132 will be less affected by the humidity of the contents, thereby suppressing a decrease in the gas barrier properties of the gas barrier layer 132. In addition, by positioning the gas barrier layer 132 closer to the outer circumferential surface 130a of the cylindrical body 130, it will be less affected by the contents compared to when it is positioned closer to the inner circumferential surface 130b of the cylindrical body 130. Furthermore, if the thickness of the outer layer 131 and inner layer 133 is greater than that of the gas barrier layer 132, moisture will have difficulty reaching the gas barrier layer 132, making it easier to maintain the performance of the gas barrier layer 132. In addition to gas barrier properties, it is also preferable to make the outer layer 131 and inner layer 133 thicker than the gas barrier layer 132 from the standpoint of material recyclability.

[0061] The thickness of the gas barrier layer 132 is preferably 10 to 300 μm, and more preferably 20 to 250 μm. The thickness of the outer layer 131 is preferably 50 to 300 μm, and more preferably 100 to 250 μm. The thickness of the inner layer 133 is preferably 150 to 500 μm, and more preferably 200 to 400 μm. The thickness of the inner layer 133 is preferably at least 1.3 times the thickness of the outer layer 131.

[0062] As examples of adhesives that make up the adhesive layer for bonding the outer layer 131 and the gas barrier layer 132, and the adhesive layer for bonding the gas barrier layer 132 and the inner layer 133, the same adhesives as those exemplified as the adhesive resins that make up the adhesive resin layers 24 and 25 can be used. The thickness of the adhesive layer is preferably 10 to 50 μm, and more preferably 15 to 40 μm.

[0063] The cylindrical body 130 can be formed, for example, by extrusion molding. More specifically, the cylindrical body 130 is formed by cutting a long member formed by extrusion molding to a predetermined length.

[0064] However, the present invention is not limited to the embodiments described above. For example, the laminated packaging bag 1 may be modified by changing the five-layer intermediate layer to a three-layer intermediate layer 20 as exemplified in Figure 2. This laminated packaging bag may be used to make a packaging bag, a spouted packaging bag, or a spouted packaging bag with contents. Furthermore, for example, instead of using a side-gusseted bag, the packaging bag 110 may be in the form of other types of packaging bags such as a bottom-gusseted bag, a spouted packaging bag, or a spouted packaging bag with contents inside. Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Examples]

[0065] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following description.

[0066] (Multilayer co-extruded film (A)) The multilayer co-extruded film (A) used in this embodiment is shown below. Multilayer co-extruded film A-1: ​​A multilayer co-extruded film with a total thickness of 70 μm, consisting of a laminated structure of HDPE layer (thickness 25 μm) / adhesive resin layer (thickness 5 μm) / EVOH layer (thickness 10 μm) / adhesive resin layer (thickness 5 μm) / HDPE layer (thickness 25 μm). Multilayer co-extruded film A-2: A multilayer co-extruded film with a total thickness of 68 μm, consisting of a laminated structure of LLDPE layer (thickness 25 μm) / adhesive resin layer (thickness 5 μm) / EVOH layer (thickness 8 μm) / adhesive resin layer (thickness 5 μm) / LLDPE layer (thickness 25 μm). Multilayer co-extruded film A-3: A multilayer co-extruded film with a total thickness of 68 μm, consisting of a laminated structure of PP layer (thickness 25 μm) / adhesive resin layer (thickness 5 μm) / EVOH layer (thickness 8 μm) / adhesive resin layer (thickness 5 μm) / PP layer (thickness 25 μm).

[0067] [Example 1] (1) Preparation of laminates for packaging bags A biaxially oriented polypropylene film (OPP, 30 μm thick) was prepared as the base layer, and printing was performed on the corona-treated surface of the OPP using a gravure printing machine. Using a tandem dry laminating machine, a general-purpose aliphatic ester adhesive was applied to the printed surface of the OPP, and it was laminated with a multilayer co-extruded film A-1 (68 μm thick) to be used as an intermediate layer. A general-purpose aliphatic ester adhesive was then applied again, and an LLDPE film (70 μm thick) was laminated as a sealant layer. After aging under predetermined conditions, the laminate was slit to a predetermined width using a slitter machine to obtain a roll-shaped laminate for packaging bags.

[0068] (2) Preparation of packaging bags with spouts Using the resulting laminated material for packaging bags, a standing-type packaging bag with a bottom gusset was manufactured using a standing-bag making machine. The dimensions of the packaging bag, in its flattened state, were 140 mm in length (height), 85 mm in width, and 25 mm in length of the bottom gusset (length from the bottom edge to the fold). Subsequently, a spout was inserted through the opening of the standing bag, and the spout was attached using a spout attachment machine to obtain a packaging bag with a spout. Furthermore, the temperature settings of the heat sealing devices in the bag-making machine and spout attachment machine were set to conditions that allow the sealant layer to be heat-fused.

[0069] [Examples 2, 3 and Comparative Example 1] A laminate for packaging bags was obtained in the same manner as in Example 1, except that the lamination structure of the laminate for packaging bags was changed as shown in Table 1. Furthermore, a packaging bag with a spout was obtained in the same manner as in Example 1, except that the obtained laminate for packaging bags was used.

[0070] Table 1 shows the lamination configuration of the packaging bag laminates for each example and the polyolefin monomaterial content of the packaging bag laminates. Table 2 shows the polyolefin monomaterial content of the packaging bags and spouted packaging bags for each example. In Table 1, " / / " indicates an adhesive layer consisting of an aliphatic ester adhesive applied during lamination in the dry lamination method. "OPP" refers to biaxially oriented polypropylene film. "CPP" refers to unoriented polypropylene film manufactured by the casting method.

[0071] [Table 1]

[0072] [Table 2]

[0073] [Processing suitability for bag making and spout attachment] In Examples 1 to 3, the difference between the melting point of the base layer and the melting point of the sealant layer was large, and in all cases, the sealing performance was good. In particular, in Example 1, the thermal shrinkage of the sealed portion due to the heat of the sealing device of the bag-making machine and spout attachment machine was smaller compared to Example 2, resulting in a good appearance of the packaging bag and the spouted packaging bag, good processability, and slightly less product loss during bag making compared to Example 2. On the other hand, in Comparative Example 1, the sealant layer was made of polypropylene, which had a higher melting point compared to the sealant layers of Examples 1 to 3. As a result, the temperature setting of the sealing device had to be set relatively 10 to 20°C higher. Furthermore, because the melting points of the base layer and the sealant layer were close, the packaging bag warped due to thermal shrinkage of each sealed portion, resulting in a poor appearance of the packaging bag and difficulties in processing suitability.

[0074] [Evaluation of strength] (1) Preparation of experimental samples 140 mL of tap water was filled into a spout-equipped packaging bag, sealed with the cap, boiled at 90°C for 30 minutes, and then stored overnight at 5°C.

[0075] (2) Compression resistance test The following compression resistance tests were conducted to demonstrate the load-bearing strength (compression resistance) of spout-equipped packaging bags. Experimental samples were placed with the flat side of the spout-equipped packaging bag facing downwards, and a predetermined load was applied from above for 1 minute. Leakage and bag rupture were visually checked. Four load conditions were used: 70 kg, 80 kg, 100 kg, and 120 kg. Tests were conducted in order from the lowest load condition, and any experimental samples showing leakage or rupture were terminated at that point. The same test was performed on a total of 10 spout-equipped packaging bags. This compression resistance test is designed to confirm whether the packaging bag can withstand various loads applied during the distribution process, such as storage and transportation. Specifically, this test involves applying a compression load, which is expected to occur during the distribution process, to the spouted packaging bag and checking for leakage from the seal and rupture of the bag.

[0076] (3) Bag drop test One set of drop tests consisted of dropping the experimental sample from a height of 1.5 m with its length aligned horizontally, followed by dropping it vertically. Up to five sets of drop tests were performed. In the horizontal drop test, the flat surface of the spouted packaging bag touched the ground, while in the vertical drop test, the bottom seal of the spouted packaging bag touched the ground. Leakage was checked after each set, and the test was terminated if leakage was detected. The same test was performed on a total of 10 spouted packaging bags.

[0077] The results of the compression resistance tests for each example are shown in Table 3. In Table 3, the total number of samples tested is shown to the right of the " / ", and the number of samples in which leakage or rupture was observed is shown to the left of the [ / ]. For example, "0 / 10" means that out of 10 samples, 0 samples showed leakage or rupture.

[0078] [Table 3]

[0079] The results of the bag drop test for each example are shown in Table 4. In Table 4, the total number of samples tested is shown to the right of " / ", and the number of samples that showed leakage is shown to the left of [ / ]. For example, "0 / 10" means that out of 10 samples, 0 samples showed leakage.

[0080] [Table 4]

[0081] As shown in Tables 3 and 4, the spouted packaging bags of Example 1 and Example 2 were confirmed to have excellent compressive strength and drop strength. On the other hand, the spouted packaging bag of Comparative Example 1 was found to have ruptured after the first set, indicating that it was not sufficiently durable in terms of practical use as a packaging container for liquids. [Explanation of symbols]

[0082] 1...Laminate for packaging bags, 10...Base layer, 20...Intermediate layer, 21...Gas barrier resin layer, 22,23...Support layer, 24,25...Adhesive resin layer, 30...Sealant layer, 100...Packaging bag with spout, 110...Packaging bag, 111...Front film, 112...Rear film, 113,114...Side film, 120...Spout, 121...Spout body, 122...Cap, 123...Dispensing part, 124...Straw part, 125...Base, 126...Mounting part, 127...Male screw, 128...Cap body, 129...Band, 130...Cylindrical body, 131...Outer layer, 132...Gas barrier layer, 133...Inner layer.

Claims

1. A laminate for packaging bags, in which a base layer, an intermediate layer, and a sealant layer, each made of plastic film, are laminated in this order, The aforementioned substrate layer is a stretched film made of polypropylene. The intermediate layer is an unstretched multilayer co-extruded film comprising a gas barrier resin layer and support layers made of high-density polyethylene with a density of 0.940 to 0.970 g / cm³ laminated on both sides of the gas barrier resin layer. The sealant layer is a film with a thickness of 30 to 200 μm, consisting of one or more homopolymers or copolymers of ethylene. The space between the substrate layer and the intermediate layer, and the space between the intermediate layer and the sealant layer, are each bonded layers of an aliphatic ester adhesive formed by the dry lamination method. The difference between the melting point of the substrate layer and the melting point of the sealant layer is 20 to 85°C. A laminate for packaging bags that contain fluid contents.

2. The laminate for packaging bags according to claim 1, wherein the gas barrier resin layer contains an ethylene-vinyl alcohol copolymer.

3. The laminate for packaging bags according to claim 2, wherein the ethylene unit content of the ethylene-vinyl alcohol copolymer is 20 mol% or more and 70 mol% or less.

4. The laminate for packaging bags according to any one of claims 1 to 3, wherein the polyolefin monomaterial content of the multilayer co-extruded film is 75% or more by mass.

5. A packaging bag made of a laminate for packaging bags according to any one of claims 1 to 4.

6. A spouted packaging bag, wherein a spout is attached to the packaging bag according to claim 5.

7. The spouted packaging bag according to claim 6, wherein the spout includes a gas barrier layer.

8. A spouted packaging bag containing contents, wherein the contents are contained within the spouted packaging bag according to claim 6 or 7.

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