Composite film, packaging bag, lid material, container with lid, and method for manufacturing composite film

Abstract

To provide a composite film which can achieve steam removal performance equivalent to conventional steam removal performance even when only one resin layer having thermosetting property is arranged between a base material layer and a heat-seal layer, provides a half cut in a necessary part and thereby can specify a part where steam is removed in heating by a microwave oven, and suppresses occurrence of lamination-lift; a packaging bag, a lid material and a container with a lid which are formed of the composite film, and a method for manufacturing a composite film.SOLUTION: An adhesive composition having a specific structure is applied as a thermosetting adhesive resin layer of a composite film that is used as a packaging material. Specifically, it is a composite film in which at least a base material layer, a thermosetting adhesive resin layer and a heat seal layer are laminated in this order, and the thermosetting adhesive resin layer is composed of a thermosetting adhesive resin forming a crosslinking structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite film, a packaging bag, a lid material, a container with a lid, and a method for producing a composite film. [Background technology]

[0002] Conventionally, pouch products filled with food have required the pouch to be opened before heating in a microwave oven in order to remove the water vapor generated inside the container.

[0003] In response to this, packaging sheets have been proposed that form steam release holes when heated in a microwave oven.For example, Patent Document 1 discloses a packaging sheet material for food to be cooked in a microwave oven, in which a base film and a sealant film are laminated together, and proposes that the sealant film be a laminate of layers made of thermoplastic resins that have different melting points and are heat-adhesive to each other, so that heating during microwave cooking partially destroys the heat-sealed parts of the packaging sheet material where the sealant film is heat-sealed, thereby forming release holes.

[0004] The packaging sheet material described in Patent Document 1 allows steam to pass through from any location in the heat-sealed portion, but it has not been possible to allow steam to pass through from a specific location in the heat-sealed portion.

[0005] In response to this, a microwave pouch is known that allows steam to be released from a desired location.

[0006] For example, Patent Document 2 proposes a laminate as a packaging material for a pouch, in which a base layer, a heat-softening layer, and a heat-seal layer are laminated in this order. It also proposes that by making a half cut on the heat-seal layer side of the laminate, steam can pass through the half cut at the heat-sealed portion where the heat-sealed layers are thermally fused together when the laminate is cooked in a microwave oven. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-165771 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-124859 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the packaging material described in Patent Document 2 had an adhesive layer in addition to the heat-softening resin layer between the base layer and the heat-sealing layer. Specifically, in Patent Document 2, the heat-softening resin layer was disposed only in the half-cut region, and the heat-softening resin layer was embedded and scattered among the adhesive layer disposed over the entire surface.

[0009] Therefore, the packaging material described in Patent Document 2 has the problem that not only is the manufacturing process for the laminate complicated, but the cost is also high.

[0010] The present invention has been made in view of the above background, and aims to provide a composite film, a packaging bag, a lid material, a lidded container, and a method for manufacturing a composite film, which can achieve steam release performance equivalent to that of conventional films even when only one layer of a heat-softenable resin is disposed between a base layer and a heat-sealing layer, and which can specify the location of steam release when heated in a microwave oven or the like by providing half cuts in required locations, and which further suppresses the occurrence of lamination lifting. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by using an adhesive composition with a specific configuration as a heat-softenable resin layer of a composite film that serves as a packaging material, which has led to the completion of the present invention. That is, the present invention is as follows.

[0012] <<Aspect 1>> A composite film in which at least a base layer, a heat-softenable adhesive resin layer, and a heat-sealable layer are laminated in this order, The heat-softenable adhesive resin layer is composed of a heat-softenable adhesive resin having a crosslinked structure. Composite film. <<Aspect 2>> 2. The composite film of claim 1, wherein the heat-softenable adhesive resin is formed from an adhesive composition containing 1 part by weight of a base resin and less than 0.2 parts by weight of a curing agent. Aspect 3 2. The composite film of claim 1, wherein the heat-softenable adhesive resin is formed from an adhesive composition containing more than 0.125 parts by weight and less than 0.2 parts by weight of a curing agent per part by weight of a base resin. Aspect 4 The heat-softenable adhesive resin layer has a coating amount of the adhesive composition of 2.5 g / m 2 4. The composite film of any one of claims 2 to 3, wherein the composite film is less than 1000 layers. Aspect 5 A composite film according to any one of aspects 1 to 4, wherein the thermosoftenable adhesive resin is an ether-based resin. Aspect 6 The lamination strength between the base layer and the heat seal layer at 25°C is 1.3 N / 15 mm or more, The lamination strength between the base layer and the heat seal layer at 70°C is 0.6 N / 15 mm or less. A composite film according to any one of aspects 1 to 5. Aspect 7 The composite film according to any one of aspects 1 to 6, wherein the composite film has a half cut applied from the heat seal layer side and reaching the heat-softenable adhesive resin layer. Aspect 8 A packaging bag formed from the composite film according to aspect 7, comprising a seal portion formed by heat-sealing the heat-sealable layers to each other, The half cut crosses the seal portion from the inside to the outside of the packaging bag. Aspect 9 The packaging bag of embodiment 8, which is for use in a microwave oven. Aspect 10 A lid material for sealing an upper opening of a container body, the lid material being formed from the composite film according to aspect 7, The sealing is performed by heat-sealing the heat-seal layer to the container body so that the lid material covers the upper end opening, thereby forming an openable joint, The half cut is arranged across the joint from the inside to the outside of the container body, a lid material. Aspect 11 A lid material according to aspect 10, which is for use in a microwave oven. Aspect 12 A container body; a lid formed from the composite film according to aspect 7 for sealing an upper opening of the container body; A container with an openable lid comprising: The upper end opening of the container body has a flange, the heat seal layer is heat sealed to the flange to form a releasable joint; The half cut crosses the joint from the inside to the outside of the container body. Openable container with lid. Aspect 13 13. The container with lid of embodiment 12, which is suitable for use in a microwave oven. Aspect 14 A method for producing a composite film according to aspect 7, comprising the steps of: a half-cutting step of cutting the sheet including the heat-sealable layer by a rotary die cutter so as to penetrate the heat-sealable layer in a thickness direction; a lamination step of laminating the base material layer and / or the heat-softenable adhesive resin layer on the sheet including the heat-sealable layer after the half-cut preparation step, A method for manufacturing a composite film. [Effects of the Invention]

[0013] According to the composite film of the present invention, even if only one layer of a heat-softenable resin layer is disposed between the base layer and the heat-seal layer, it is possible to produce packaging bags such as pouches and openable containers that have vapor release performance equivalent to that of conventional products.

[0014] Furthermore, when no adhesive layer other than the heat-softenable adhesive resin layer is disposed between the base layer and the heat-sealing layer, the manufacturing process of the composite film can be simplified, which can contribute to production capacity and production costs.

[0015] Furthermore, by providing half cuts at necessary locations, steam can be released from the intended location when heating in a microwave oven or the like.

[0016] Furthermore, the composite film of the present invention is a composite film in which the occurrence of lamination lifting during storage and the resulting poor appearance are suppressed, and therefore packaging materials made from the composite film of the present invention can improve the storage properties of contents such as food. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a composite film according to one embodiment of the present invention. [Figure 2] 1 is a diagram showing a packaging bag according to one embodiment of the present invention. [Figure 3] 1 is a schematic diagram of a packaging bag according to an embodiment of the present invention when steam is released. DETAILED DESCRIPTION OF THE INVENTION

[0018] Composite film The composite film of the present invention is a composite film in which at least a base material layer, a heat-softenable adhesive resin layer, and a heat-sealable layer are laminated in this order, and the heat-softenable adhesive resin layer is composed of a heat-softenable adhesive resin having a crosslinked structure. Composite film.

[0019] <<Configuration of composite film>> The structure of the composite film of the present invention will be described below with reference to the drawings: Figure 1 shows a cross-sectional view of one embodiment of the composite film of the present invention.

[0020] A composite film 10 according to one embodiment of the composite film of the present invention shown in FIG. 1 includes a base layer 1, a heat-softenable adhesive resin layer 2 laminated on the inner side of the base layer 1, and a heat-seal layer 3 laminated on the inner side of the heat-softenable adhesive resin layer 2.

[0021] The composite film of the present invention essentially comprises a substrate layer, a heat-softenable adhesive resin layer, and a heat-seal layer, which are laminated in this order. In the present invention, an optional layer may be provided in addition to the substrate layer, the heat-softenable adhesive resin layer, and the heat-seal layer. Examples of the optional layer include a barrier layer for imparting barrier properties, a reinforcing layer for reinforcing strength, and an adhesive layer for bonding layers together.

[0022] The composite film 10 shown in FIG. 1 is an embodiment that includes only the base material layer 1, the heat-softenable adhesive resin layer 2, and the heat-seal layer 3, which are essential components of the present invention. However, other layers may be present, for example, between the base material layer 1, the heat-softenable adhesive resin layer 2, and the heat-seal layer 3, or on the outside of the laminate including these layers.

[0023] The thickness of each layer constituting the composite film of the present invention can be appropriately determined depending on the intended use of the composite film.

[0024] <Base material layer> The substrate layer is an essential constituent layer of the composite film of the present invention.

[0025] In the composite film of the present invention, the substrate layer, the heat-softenable adhesive resin layer, and the heat-seal layer are laminated in this order, and therefore the substrate layer becomes the outer layer of a structure such as a packaging bag or a package when the structure is formed. Therefore, the substrate layer can serve as a protective layer when the innermost heat-seal layer is heat-sealed to form a structure. The substrate layer can also serve as a printing layer on which printing is performed to indicate the contents, etc.

[0026] The material constituting the base layer is not particularly limited as long as it is a resin, etc., particularly a resin that can be used as a protective layer and that can be printed on. Commonly used resins can be used, for example, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT), polyolefins such as polyethylene (PE), polypropylene (PP), and polystyrene (PS), polyamides (PA) such as nylon-6 and nylon-66, and polycarbonate (PC).

[0027] The resins constituting the base layer may be one type or a blend of two or more types, and additives for imparting functionality, etc. may be blended as necessary.

[0028] The substrate layer is preferably made from a preformed film. The film to be the substrate layer may be a film formed from the above-mentioned resin or the like, and may be unstretched or uniaxially or biaxially stretched. Among these, a biaxially stretched film is preferred.

[0029] The film serving as the substrate layer may be vapor-deposited with an oxide such as silicon oxide or aluminum oxide.

[0030] Furthermore, the film serving as the substrate layer may be a single layer or a laminate consisting of multiple layers.

[0031] <Thermosoft adhesive resin layer> The heat-softenable adhesive resin layer is an essential constituent layer of the composite film of the present invention, and is disposed between the substrate layer and the heat-sealable layer.

[0032] (thermosoftening adhesive resin) The thermosoftenable adhesive resin constituting the thermosoftenable adhesive resin layer of the present invention has a crosslinked structure. The material for forming the thermosoftenable adhesive resin is not particularly limited, and any material can be used as long as it can form a crosslinked structure, be softened by heat, and form a resin layer having adhesive properties. 。

[0033] The thermosoftenable adhesive composition that is the material for forming the thermosoftenable adhesive resin may be, for example, an adhesive composition that contains a base agent and a curing agent.

[0034] {Main ingredient} The main agent constituting the adhesive composition, which is the material for forming the thermosoftenable adhesive resin, is not particularly limited, but is preferably liquid at room temperature from the viewpoint of facilitating dry lamination onto the substrate layer. Examples of the main agent include polyols, such as polycarbonate polyols, polycaprolactone polyols, polyester polyols, polyether polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols. The main agent may be used alone or in combination of two or more.

[0035] Among these, polyester polyols or polyether polyols are preferably used, and from the viewpoint of rapid curing, at least one polyol selected from the group consisting of polyester polyurethane polyols and polyether polyurethane polyols is more preferred.

[0036] In particular, polyether polyols capable of forming an ether-based resin layer are suitable, and the polyether polyol may be polyether polyurethane polyol.

[0037] {hardening agent} The curing agent constituting the adhesive composition, which is the material for forming the thermosoftenable adhesive resin, is not particularly limited, but is preferably a curing agent that is liquid at room temperature from the viewpoint of facilitating dry lamination onto the base layer. Examples of the curing agent include polyisocyanate.

[0038] Examples of polyisocyanates include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanatomethyl caproate; Alicyclic diisocyanates such as cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, and 1,3-bis(isocyanatomethyl)cyclohexane, m-phenylenediisocyanates Isocyanates, p-phenylene diisocyanate, 4,4-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate or 2,6-tolylene diisocyanate or a mixture thereof, aromatic diisocyanates such as 4,4'-toluidine diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and tetramethylxylylene Examples of the polyisocyanate include diisocyanates or mixtures thereof, aromatic aliphatic diisocyanates such as ω,ω'-diisocyanato-1,4-diethylbenzene, aromatic or aromatic aliphatic organic triisocyanates such as triphenylmethane-4,4'4"-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene, and organic tetraisocyanates represented by aromatic aliphatic tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.The polyisocyanate may be a derivative or adduct obtained by reacting these monomers with other compounds, or a derivative such as a dimer or trimer derived from these monomers.

[0039] {Composition ratio of base agent and hardener} The composition ratio of the main agent and curing agent contained in the adhesive composition, which is the material for forming the thermosoftenable adhesive resin, may be, for example, 1 part by mass of the main agent to less than 0.2 parts by mass of the curing agent.

[0040] When the composition ratio of the main agent to the curing agent in the adhesive composition is 0.2 parts by mass or more of the curing agent per 1 part by mass of the main agent, a heat-softenable adhesive resin layer having high lamination strength at 70°C is formed between the substrate layer and the heat seal layer, and as a result, the resulting composite film has reduced vapor release performance.

[0041] On the other hand, if the composition ratio of the main agent to the curing agent in the adhesive composition is less than 0.01 parts by mass of the curing agent per 1 part by mass of the main agent, a heat-softenable adhesive resin layer is formed that has a low strength for bonding the substrate layer and the heat-sealable layer, and as a result, the resulting composite film has low lamination strength at room temperature and may suffer from lamination lifting.

[0042] The composition ratio of the main agent and curing agent contained in the adhesive composition, which is the material that forms the thermosoftenable adhesive resin, may be 0.15 parts by mass or less, 0.125 parts by mass or less, 0.10 parts by mass or less, 0.075 parts by mass or less, or 0.05 parts by mass or less of the curing agent per 1 part by mass of the main agent.

[0043] On the other hand, the composition ratio of the main agent to the curing agent contained in the adhesive composition may be 0.01 parts by mass or more, 0.025 parts by mass or more, 0.05 parts by mass or more, 0.075 parts by mass or more, 0.10 parts by mass or more, 0.125 parts by mass or more, or 0.15 parts by mass or more of the curing agent per 1 part by mass of the main agent.

[0044] In particular, if the composition ratio of the main agent and curing agent contained in the adhesive composition, which is the material for forming the heat-softenable adhesive resin, is more than 0.125 mass parts and less than 0.2 mass parts of curing agent per 1 mass part of the main agent, when the composite film of the present invention has a half cut made from the heat-seal layer side and reaching the heat-softenable adhesive resin layer, leakage of the adhesive composition from the half cut can be suppressed during the processing of the composite film.

[0045] {Other ingredients} The adhesive composition that forms the thermosoftenable adhesive resin may optionally contain other components in addition to the base agent and curing agent, such as a solvent, a component for imparting functionality to the resulting thermosoftenable adhesive resin layer, or an additive.

[0046] (Laminate strength) The composite film of the present invention has a lamination strength between the substrate layer and the heat seal layer at 25°C of 1.3 N / 15 mm or more, and a lamination strength between the substrate layer and the heat seal layer at 70°C of less than 0.6 N / 15 mm.

[0047] Since the lamination strength between the base layer and the heat seal layer at 25°C is 1.3 N / 15 mm or more, the structure formed from the composite film of the present invention has sufficient strength at around room temperature, and peeling (lamination lifting) does not occur between the base layer and the heat seal layer during storage and handling.

[0048] The lamination strength at 25°C between the substrate layer and the heat seal layer may be 1.5 N / 15 mm or more, 1.8 N / 15 mm or more, 2.0 N / 15 mm or more, 2.4 N / 15 mm or more, 2.8 N / 15 mm or more, or 3.0 N / 15 mm or more.

[0049] On the other hand, the laminate strength at 25°C between the base layer and the heat seal layer may be 6.0 N / 15 mm or less, 5.0 N / 15 mm or less, 4.5 N / 15 mm or less, 4.0 N / 15 mm or less, 3.5 N / 15 mm or less, or 3.0 N / 15 mm or less.

[0050] Furthermore, since the lamination strength between the base material layer and the heat seal layer at 70°C is less than 0.6 N / 15 mm, when a structure formed from the composite film of the present invention is heated, spaces are easily formed in the heat-softenable adhesive resin layer, and steam can be moved through these spaces, thereby achieving steam release performance equivalent to that of conventional structures.

[0051] The lamination strength at 70°C between the substrate layer and the heat seal layer may be 0.5 N / 15 mm or less, 0.4 N / 15 mm or less, 0.3 N / 15 mm or less, 0.2 / 15 mm or less, 0.1 / 15 mm or less, or 0.05 N / 15 mm or less.

[0052] On the other hand, the laminate strength at 70°C between the base layer and the heat seal layer may be 0.01 N / 15 mm or more, 0.05 N / 15 mm or more, 0.1 N / 15 mm or more, 0.2 N / 15 mm or more, 0.3 N / 15 mm or more, 0.4 N / 15 mm or more, or 0.5 N / 15 mm or more.

[0053] In the composite film of the present invention, the laminate strength between the substrate layer and the heat-sealing layer at 25°C is greater than the laminate strength at 70°C, so that when the composite film of the present invention is heated in a microwave oven or the like, the laminate strength between the substrate layer and the heat-sealing layer decreases, making it easier to form spaces in the softenable resin layer, and allowing steam to migrate through the formed spaces.

[0054] <Heat seal layer> The heat seal layer is an essential constituent layer of the composite film of the present invention.

[0055] The heat seal layer is a layer that is heat-sealed when forming a structure such as a packaging bag, a package, etc. Therefore, the heat seal layer is disposed so as to be the innermost layer of the composite film.

[0056] The material for the heat seal layer is not particularly limited as long as it is heat-sealable and can provide sufficient sealing strength to the molded structure. Known materials can be used, such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), polypropylene (PP), ethylene-propylene copolymer (EP), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ionomer resin, and ethylene-vinyl acetate copolymer (EVA).

[0057] For example, when forming a structure such as a packaging bag to be filled with contents, the heat seal layer constituting the composite film of the present invention becomes a layer that forms a space for filling the contents. Therefore, when it is desired to impart resistance to contents, it is preferable to use, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), etc.

[0058] The heat seal layer may be formed using a film preformed from the above-mentioned material, or may be formed by melting and extruding a material for forming the heat seal layer onto the surface of a laminate comprising a base layer, a heat-softenable adhesive resin layer, and, if necessary, other layers, and then cooling and solidifying the material.

[0059] Furthermore, the resins constituting the heat seal layer may be one type or a blend of two or more types, and additives for imparting functionality, etc. may be blended as necessary.

[0060] Furthermore, the heat seal layer may be a single layer or may be a multi-layer structure.

[0061] The heat seal layer constituting the composite film of the present invention may have easy-peel properties (easy-open properties) so that the joint can be easily opened during use. If the heat seal layer has easy-peel properties, for example, when a lid material is formed from the composite film of the present invention and heat-sealed to a container body to form a package, the lid material can be easily opened to remove the contents.

[0062] (Half cut) The composite film of the present invention may have a half cut that is made from the heat seal layer side and reaches the heat-softenable adhesive resin layer.

[0063] Here, the half cut refers to a cut formed in the thickness direction of the composite film, but not penetrating the composite film in the thickness direction.

[0064] The composite film of the present invention has half cuts at necessary locations, so that steam can be released from intended locations when heated in a microwave oven or the like.

[0065] As described above, when a structure is formed from the composite film of the present invention, the heat seal layer is on the inside of the structure, i.e., it is the layer that comes into contact with the contents. Therefore, steam generated from the contents by heating penetrates into the composite film in the thickness direction through the half cut.

[0066] At this time, if the half cut reaches the heat-softening adhesive resin layer, the steam generated from the contents passes through the half cut and reaches the heat-softening adhesive resin layer directly. As a result, the heat of the steam directly warms the heat-softening adhesive resin layer, making it easier to soften than if it were indirectly warmed.

[0067] Therefore, by providing the composite film of the present invention with a half cut at a location where steam needs to be released, it becomes possible to release steam from an intended location.

[0068] In the composite film 10 shown in FIG. 1, the half-cut portion C is provided from the heat seal layer 3 side and reaches the surface of the heat-softenable adhesive resin layer 2.

[0069] The depth of the half cut may be up to the surface of the heat-softenable adhesive resin layer, or may be up to the inside of the heat-softenable adhesive resin layer, or may even penetrate through the heat-softenable adhesive resin layer.

[0070] However, the half cut is preferably deep enough not to reach the base layer, which is the outermost layer of the composite film, since if the half cut reaches the base layer, the strength of the structure formed from the composite film may decrease.

[0071] In particular, it is preferable that the half-cut is performed only on the heat-sealable layer. If the half-cut can be performed only on the heat-sealable layer, the effect of the half-cut can be enjoyed while the strength of the composite film is at its highest.

[0072] The shape of the half cut may be either a continuous line or an intermittent line. There is no limit to the number of half cuts, as long as there is at least one. When multiple half cuts are provided, it is preferable that the half cuts are approximately parallel to each other.

[0073] The length of the half cut is not particularly limited, and may be such that it is provided only in the area where steam release is desired, or may be provided evenly over the entire composite film.

[0074] The method for forming the half cut is not particularly limited, and for example, the half cut may be produced using a laser or the like after the composite film is formed, or the half cut may be produced from the heat seal layer side of a sheet containing a heat seal layer using a die cutter or the like during the production of the composite film, and then laminated with other layers to form a composite film.

[0075] <Other layers> The composite film of the present invention may contain layers other than the substrate layer, the heat-softenable adhesive resin layer, and the heat-sealable layer as essential constituent layers.

[0076] The other layers are not particularly limited, and examples thereof include a barrier layer for imparting barrier properties, a reinforcing layer for reinforcing strength, and an adhesive layer for bonding layers together.

[0077] Examples of barrier layers for imparting barrier properties include layers made of ethylene-vinyl alcohol copolymer (EVOH), nylon (NY), polyvinylidene chloride (PVDC), or polyacrylonitrile (PAN), which exhibit the function of blocking gases such as oxygen and water vapor.

[0078] Examples of materials for the reinforcing layer to reinforce the strength include paper, synthetic paper, nonwoven fabric, etc. These may be coated with an adhesive to provide adhesion to adjacent layers. Also, a layer made of the material constituting the above-mentioned base layer may be provided as a reinforcing layer, separate from the base layer.

[0079] Examples of adhesive layers for bonding layers include layers made of ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and ionomer.

[0080] The other layer may be a layer made of an adhesive used when dry laminating or hot melt laminating layers together.

[0081] The resins constituting the other layers may be one type or a blend of two or more types. If necessary, additives may be added to impart functionality.

[0082] <<Method for manufacturing composite film>> The method for producing the composite film of the present invention is not particularly limited, and any known method can be used, such as dry lamination, hot melt lamination, extrusion lamination, and sandwich lamination.

[0083] For example, a laminate may be formed by adhering a film that will become the base layer and a film that will become the heat seal layer with an adhesive composition that will become the heat-softenable adhesive resin layer.

[0084] When this method is used, the coating amount of the adhesive composition for forming the heat-softenable adhesive resin layer is not particularly limited, but for example, it is 5.0 g / m 2 Below 4.5g / m 2 Below 4.0g / m 2 Below 3.5g / m 2 Below 3.0g / m 2 Below 2.5g / m 2 Below 2.0g / m 2 Below 1.5g / m 2 or less, or 1.0 g / m 2 may be less than or equal to 0.25 g / m 2 More than 0.5g / m 2 More than 0.75g / m 2 More than 1.0g / m 2 More than 1.5g / m 2 It may be more than that.

[0085] Among them, the coating amount of the adhesive composition is 2.5 g / m 2 If the thickness is less than 1 / 2 mm, when the composite film of the present invention has a half cut made from the heat seal layer side and reaching the heat-softenable adhesive resin layer, leakage of the adhesive composition from the half cut can be suppressed during the processing step of the composite film.

[0086] The method for producing a composite film having half cuts is not particularly limited, but for example, a method in which half cuts are made using a laser or the like after producing a composite film can be mentioned.

[0087] Alternatively, a half-cut may be made during the production of the composite film, and the layer having the half-cut may be laminated with other layers to form a composite film. In this case, for example, a sheet including a heat-sealable layer may be cut using a rotary die cutter to penetrate the heat-sealable layer in the thickness direction (half-cut making step), and then a base layer and a heat-softenable adhesive resin layer may be laminated on the sheet including the heat-sealable layer (lamination step), thereby producing a composite film.

[0088] <<Function of composite film>> The function of the composite film of the present invention will be described below with reference to the drawings. Fig. 2 is a diagram showing a packaging bag according to one embodiment of the present invention. Fig. 3 is a schematic diagram of the packaging bag according to one embodiment of the present invention when steam is released.

[0089] The structure formed using the composite film of the present invention is not particularly limited. Since the composite film of the present invention has a heat seal layer as the innermost layer, various structures can be formed by heat-sealing the heat seal layers to each other or by heat-sealing the heat seal layer to the flange portion of a flanged container body.

[0090] Fig. 2 is a diagram showing a packaging bag formed by heat-sealing the heat-sealed layers together. In Fig. 2, the outer peripheries of the composite film 10 of the present invention having the half-cut C are heat-sealed together to form a packaging bag 100 having a seal portion 4.

[0091] The composite film 10 is a laminate made up of a base material layer 1, a heat-softenable adhesive resin layer 2, and a heat-seal layer 3, as shown in Fig. 1, and as shown in Fig. 2, each layer of the composite film 10 extends on an XY plane formed by the X direction and the Y direction, and the Z direction (not shown) is the thickness direction of the composite film 10. That is, Fig. 2 is a top view of the packaging bag 100 as seen from the base material layer 1 side.

[0092] In the composite film 10 constituting the packaging bag 100 shown in Figure 2, the half cuts C are arranged in intermittent straight lines and are formed so as to cross the seal portion 4 of the packaging bag 100 from the inside to the outside of the packaging bag 100.

[0093] When such a packaging bag 100 is heated and steam is generated from the contents filled inside the packaging bag 100, the generated steam 5 is discharged to the outside of the packaging bag 100 from the location where the half cut C of the sealed portion 4 has been made, as shown in Figure 2.

[0094] Here, the action of the steam 5 being discharged to the outside of the packaging bag 100 from the part of the sealed portion 4 where the half cut C has been made will be described with reference to FIG.

[0095] Fig. 3 is a cross-sectional view showing the Z direction (not shown) of the composite film 10. Fig. 3 also shows a state in which the packaging bag 100 shown in Fig. 2 is formed from the composite film 10 shown in Fig. 1, and when the packaging bag 100 is heated and steam 5 is generated from the contents of the packaging bag 100, the heat-softenable adhesive resin layer 2 of the composite film 10 is softened by the steam 5.

[0096] The steam 5 generated inside the packaging bag 100 penetrates the composite film 10 in the thickness direction (Z direction) through the half cut C formed in the heat seal layer 3 of the composite film 10, and when it reaches the heat softenable adhesive resin layer 2, it directly applies heat to the heat softenable adhesive resin layer 2. This causes the heat softenable adhesive resin layer 2 to soften and become flexible.

[0097] The pressure inside the packaging bag 100 increases due to the pressure of steam generated from the contents. As shown in Fig. 3, the increase in internal pressure causes delamination between the softened heat-softenable adhesive resin layer 2 and the heat-sealable layer 3, and the heat-softenable adhesive resin layer 2 is lifted to the outside of the packaging bag 100 by the pressure of the steam 5, forming a space 6 in the delaminated area.

[0098] Then, steam 5 generated from the contents is discharged from the inside to the outside of the packaging bag 100 through the space 6 that appears in the area of ​​the half cut C that is formed across the seal portion 4, as shown in Figure 2.

[0099] <<Applications of composite film>> The structure formed using the composite film of the present invention is not particularly limited.

[0100] For example, by heat-sealing the heat-sealable layers of the composite film of the present invention to each other, it is possible to form three-side sealed bags, four-side sealed bags, gusseted packaging bags, pillow packaging bags, Goebel-top type bottomed containers, Tetra Classic (registered trademark), Brick Pack (registered trademark), tube containers, etc. Furthermore, a zipper can be provided on the heat-sealable layer to form a zippered packaging bag.

[0101] Alternatively, for example, a lid material can be formed from the composite film of the present invention and heat-sealed to a container body to form an openable package.

[0102] The packaging bag and lid material using the composite film of the present invention will be described below.

[0103] (packaging bag) The packaging bag can be produced by heat-sealing the heat-sealable layers of the composite film of the present invention to each other to form a sealed portion.

[0104] At this time, the composite film may be half-cut, and the sealed portion where the heat-sealed layers are heat-fused together may be arranged so that the half-cut traverses from the inside to the outside of the packaging bag.

[0105] If the half cut is configured to cross the sealed portion from the inside to the outside of the packaging bag, a space for passing steam can be formed in the half cut portion when the packaging bag is heated. Then, steam generated inside the packaging bag can be discharged to the outside of the packaging bag through the space.

[0106] Such a packaging bag can be suitably used as a packaging bag that is heated, and is extremely useful as a packaging bag for use in a microwave oven, for example.

[0107] (lid material) The composite film of the present invention can also be used as a lid for sealing the top opening of the container body.

[0108] The container body can be sealed by forming an openable joint by heat-sealing the heat-seal layer of the composite film to the container body so that the top opening of the container is covered with a lid material made of the composite film of the present invention.

[0109] When the top opening of the container has a flange, a container with a lid may be formed by heat-sealing the heat-seal layer of the lid material made of the composite film of the present invention to the flange of the container body to form an openable joint.

[0110] In this case, if the heat seal layer has easy peel properties (easy opening properties), the formed sealed container will be a container with a lid that is easy to open.

[0111] Alternatively, the composite film may be half-cut and the half-cut may be disposed across the joint where the flange of the container body and the heat-seal layer are heat-sealed from the inside to the outside of the container body.

[0112] If the half cut crosses the joint from the inside to the outside of the container body, a space for passing steam is formed in the half cut when the sealed container is heated. Then, steam generated inside the sealed container can be discharged to the outside of the sealed container through the space.

[0113] Such a lidded container can be suitably used as a lidded container that is heated, and is extremely useful, for example, as a lidded container for use in a microwave oven. [Example]

[0114] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0115] <Material> In the examples and comparative examples, the following materials were prepared as materials for constituting the layers.

[0116] (1) Base material layer PET#12: Biaxially stretched PET film (Toyobo Ester (registered trademark) E5100, Toyobo Co., Ltd., thickness: 12 μm) OPP#20: Biaxially stretched PP film (Pylen (registered trademark) P2161, Toyobo Co., Ltd., thickness: 20 μm) Ny#15: Nylon film (Bonyl (registered trademark) RX, Kohjin Film & Chemicals Co., Ltd., thickness: 15 μm)

[0117] (2) Heat-softening adhesive resin layer TM-396 (base agent) / CAT-22B (hardener) (Toyo-Morton Co., Ltd.) Elitel (registered trademark) XP-1586 (Unitika Ltd.)

[0118] (3) Heat seal layer CPP#20: Unstretched PP film (Pylen (registered trademark) P1128, Toyobo Co., Ltd., thickness: 20 μm) CPP#30: Unstretched PP film (Pylen (registered trademark) P1128, Toyobo Co., Ltd., thickness: 30 μm) E1901T#50: Laminated PP film (Diffarene (registered trademark) E1901T, DIC Corporation, thickness: 50 μm)

[0119] Examples 1 to 4, Comparative Examples 1 to 6, and Reference Example 1 <Manufacturing of composite film> Using the materials shown in Table 1 or 2, a film serving as a base layer and a film serving as a heat-sealable layer were bonded together with an adhesive composition that forms a heat-softenable adhesive resin layer to prepare a laminate. The coating amount of the adhesive composition was 3.0 g / m. 2It was decided.

[0120] The film that would become the heat seal layer in the laminate was cut to penetrate the heat seal layer in the thickness direction (half cut production process), and then a base layer and a heat-softenable adhesive resin layer were laminated on the sheet containing the heat seal layer to obtain a composite film with a half cut.

[0121] <Laminate strength measurement> The composite films obtained in Examples 1 to 4, Comparative Examples 1 to 6, and Reference Example 1 were cut to a width of 15 mm, and the interlaminar strength between the base layer and the heat-sealing layer was measured in an atmosphere of 25°C and 70°C. The measurements were carried out by T-peel at a rate of 300 mm / min, and the average value was calculated over a displacement range of 20 to 50 mm. The results are shown in Table 1 or Table 2. In the tables, "material failure" means that the laminate strength was too high, causing the material to break during peeling, making it impossible to measure.

[0122] <Pouch production> Pillow bags with inner dimensions of 130 mm x 135 mm were produced using the composite films produced in Examples 1 to 4, Comparative Examples 1 to 6, and Reference Example 1. A paper wiper (Kimwipe (registered trademark), manufactured by Nippon Paper Crecia) soaked with 10 cc of water was enclosed inside the pillow bag. The half-cut was placed in the sealed portion of the pillow bag so as to cross the sealed portion from the inside to the outside of the packaging bag. The pillow bags were produced using an impulse sealer with heating for 0.9 seconds and cooling for 2.0 seconds.

[0123] <Evaluation of steam permeability of pouches> The prepared pouches were microwaved for 60 seconds in a microwave oven (700W). At this time, it was visually confirmed whether steam inside the pouch had been released from the heat-sealed portion. Each pouch was microwaved five times and evaluated according to the following criteria. The results are shown in Table 1 or Table 2. ○: Steam was released in all five cases. ×: Steam was not discharged at least once.

[0124] <Evaluation of pouch lamination> Five pouches were prepared in the same manner as above and left to stand for one day in an atmosphere at 25°C. After standing, the presence or absence of lamination was visually confirmed and evaluated according to the following criteria. The results are shown in Table 1 or Table 2. ◯: There was no lamination in all five pouches. △: Separation of lamination was observed in 1 to 3 pouches. ×: Lamination was observed in 4 to 5 pouches.

[0125] [Table 1]

[0126] [Table 2]

[0127] Examples 5 to 9, Comparative Example 7 <Manufacturing of composite film> A laminate was produced by bonding a film to serve as the base layer and a film to serve as the heat-sealable layer with an adhesive composition that forms a heat-softenable adhesive resin layer using the materials shown in Table 3. The amount of adhesive composition applied was the amount shown in Table 3.

[0128] As in Example 1, a cut was made in the film that would become the heat seal layer in the laminate, penetrating the heat seal layer in the thickness direction (half cut production process), and then a base layer and a heat-softenable adhesive resin layer were laminated on the sheet containing the heat seal layer to obtain a composite film with a half cut.

[0129] <Laminate strength measurement> The interlaminar strength between the base layer and the heat seal layer was measured in the same manner as in Example 1. The results are shown in Table 3.

[0130] <Pouch production> In the same manner as in Example 1, a pillow bag with inner dimensions of 130 mm x 135 mm was prepared.

[0131] <Evaluation of steam permeability of pouches and evaluation of pouch lamination> The steam permeability of the pouch and the lamination separation of the pouch were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0132] <Evaluation of adhesive leakage from half cut> In Examples 5 to 9 and Comparative Example 7, each raw roll of composite film was prepared in a 4000 m roll, and after aging, it was taken out and immediately rewound. During rewinding, it was checked whether any leaked adhesive had adhered to the roll, etc., and evaluated according to the following evaluation criteria. The results are shown in Table 3. ○: No adhesive leakage was observed. △: Slight leakage (does not affect processing) ×: Leakage of adhesive was observed.

[0133] [Table 3] [Explanation of symbols]

[0134] 10 Composite Film 1 Base material layer 2 Heat-softening adhesive resin layer 3 Heat-seal layer 4 Seal part 5. Steam 6 Space 100 packaging bags C Half Cut

Claims

1. A composite film in which at least a base layer, a heat-softenable adhesive resin layer, and a heat-sealable layer are laminated in this order, the heat-softenable adhesive resin layer is made of a heat-softenable adhesive resin having a crosslinked structure, The lamination strength between the base layer and the heat seal layer at 25°C is 1.3 N / 15 mm or more, The lamination strength between the base layer and the heat seal layer at 70°C is 0.6 N / 15 mm or less, and a half cut applied from the heat seal layer side and reaching the heat-softenable adhesive resin layer; Composite film.

2. The composite film according to claim 1 , wherein the heat-softenable adhesive resin is formed from an adhesive composition containing less than 0.2 parts by mass of a curing agent per 1 part by mass of a base resin.

3. The composite film according to claim 1 , wherein the heat-softenable adhesive resin is formed from an adhesive composition containing more than 0.125 parts by mass and less than 0.2 parts by mass of a curing agent per 1 part by mass of a base resin.

4. The heat-softenable adhesive resin layer has a coating amount of the adhesive composition of 2.5 g / m ２ 4. The composite film of claim 2 or 3, which is less than 1000 layers.

5. The composite film according to any one of claims 1 to 4, wherein the thermosoftenable adhesive resin is an ether-based resin.

6. A packaging bag formed from the composite film according to any one of claims 1 to 5, comprising a seal portion formed by heat-sealing the heat-sealing layers to each other, The half cut crosses the seal portion from the inside to the outside of the packaging bag.

7. The packaging bag according to claim 6, which is suitable for use in a microwave oven.

8. A lid material formed from the composite film according to any one of claims 1 to 5 for sealing an upper end opening of a container body, The sealing is performed by heat-sealing the heat-seal layer to the container body so that the lid material covers the upper end opening, thereby forming an openable joint, The half cut is arranged across the joint from the inside to the outside of the container body, a lid material.

9. The lid material according to claim 8, which is for use in a microwave oven.

10. A container body; A lid material formed from the composite film according to any one of claims 1 to 5 for sealing an upper end opening of the container body; A container with an openable lid comprising: The upper end opening of the container body has a flange, the heat seal layer is heat sealed to the flange to form a releasable joint; The half cut crosses the joint from the inside to the outside of the container body. Openable container with lid.

11. The container with lid according to claim 10, which is suitable for use in a microwave oven.

12. A method for producing a composite film according to any one of claims 1 to 5, comprising: a half-cutting step of cutting the sheet including the heat-sealable layer by a rotary die cutter so as to penetrate the heat-sealable layer in a thickness direction; a lamination step of laminating the base material layer and / or the heat-softenable adhesive resin layer on the sheet including the heat-sealable layer after the half-cut preparation step, A method for manufacturing a composite film.

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