Packaging material, method for manufacturing same, and packaging bag

Abstract

This packaging material has a structure in which a transparent vapor-deposited barrier film, a stretched nylon film, and an unstretched polypropylene film are laminated in this order. The transparent vapor-deposited barrier film and the stretched nylon film are laminated with an adhesive layer formed of a cured product of a solventless adhesive agent therebetween. The ratio of the Young's modulus in the MD direction of the unstretched polypropylene film with respect to the thickness of the unstretched polypropylene film is 9.0 MPa / μm or more.

Description

Packaging material, its manufacturing method, and packaging bag

[0001] The present disclosure relates to a packaging material, a manufacturing method thereof, and a packaging bag.

[0002] Conventionally, multilayer films formed by laminating films having various functions have been used as packaging materials for packaging foods, medicines, etc. For example, Patent Document 1 discloses a packaging material formed by laminating a polyethylene terephthalate film, a vapor-deposited barrier film, an oriented nylon film, and an unoriented polypropylene film by a dry lamination method. The vapor-deposited barrier film has high transparency and is therefore also called a transparent vapor-deposited barrier film.

[0003] Japanese Patent Application Laid-Open No. 2006-117275

[0004] In the above Patent Document 1, a solvent-based adhesive is used to bond the films together, but in recent years, from the viewpoint of reducing the environmental load, etc., it has become desirable to use a solvent-free adhesive.

[0005] However, when a solvent-free adhesive is used, the curing period for hardening the adhesive may become long, and air bubbles may remain between the films (particularly at the interface between the adhesive layer and the film) due to unevenness on the coating surface caused by the high viscosity of the adhesive. Such air bubbles occur significantly when a solvent-free adhesive is used to bond a barrier film to a stretched nylon film, and when the barrier film is a transparent vapor-deposited barrier film, they are visually recognized as spotty (for example, orange peel-like, matte, etc.) appearance defects.

[0006] Therefore, one aspect of the present disclosure aims to suppress the appearance defects that occur when a solvent-free adhesive is used to bond a transparent vapor-deposited barrier film and a stretched nylon film in the production of a packaging material. Another aspect of the present disclosure aims to provide a packaging material in which the appearance defects are suppressed.

[0007] Some aspects of the present disclosure provide the following [1] to

[15] .

[0008] [1] A packaging material having a structure in which a transparent vapor-deposited barrier film, a stretched nylon film, and an unstretched polypropylene film are laminated in this order, the transparent vapor-deposited barrier film and the stretched nylon film are laminated via an adhesive layer made of a cured product of a solvent-free adhesive, and the ratio of Young's modulus in the MD direction of the unstretched polypropylene film to the thickness of the unstretched polypropylene film is 9.0 MPa / μm or more.

[0009] [2] The packaging material according to [1], wherein the Young's modulus in the MD direction of the unstretched polypropylene film is 450 MPa or more.

[0010] [3] The packaging material according to [1] or [2], wherein the Young's modulus in the MD direction of the unstretched polypropylene film is 1200 MPa or less.

[0011] [4] The packaging material according to any one of [1] to [3], wherein the thickness of the unstretched polypropylene film is 100 μm or less.

[0012] [5] The packaging material according to any one of [1] to [4], wherein the thickness of the unstretched polypropylene film is 10 μm or more.

[0013] [6] The packaging material according to any one of [1] to [5], wherein the ratio of the Young's modulus in the MD direction of the unstretched polypropylene film to the thickness of the unstretched polypropylene film is 18.0 MPa / μm or less.

[0014] [7] The packaging material according to any one of [1] to [6], wherein the ratio of the Young's modulus in the MD direction of the stretched nylon film to the thickness of the stretched nylon film is 100 to 250 MPa / μm.

[0015] [8] The packaging material according to any one of [1] to [7], wherein the Young's modulus in the MD direction of the stretched nylon film is 2000 to 5000 MPa.

[0016] [9] The packaging material according to any one of [1] to [8], wherein the thickness of the stretched nylon film is 50 μm or less.

[0017]

[10] The packaging material according to any one of [1] to [9], wherein the transparent vapor deposition barrier film has a structure in which a resin film, a transparent vapor deposition layer, and a protective layer are laminated in this order, and the resin film is disposed as an outer layer and the protective layer is disposed as an inner layer.

[0018]

[11] The packaging material according to any one of [1] to

[10] , wherein the solventless adhesive is a polyurethane adhesive containing a polyisocyanate component and a polyol component.

[0019]

[12] The packaging material according to any one of [1] to

[11] , wherein the stretched nylon film and the unstretched polypropylene film are laminated via an adhesive layer made of a cured product of a solventless adhesive.

[0020]

[13] The packaging material according to any one of [1] to

[12] , wherein the area ratio of air bubbles to the area of ​​the adhesive layer when the adhesive layer is observed from the stacking direction is less than 1%.

[0021]

[14] A packaging bag made from the packaging material according to any one of [1] to

[13] .

[0022]

[15] A method for producing a packaging material according to any one of [1] to

[13] , comprising: preparing a laminate film having a structure in which the transparent vapor deposition barrier film, the stretched nylon film, and the unstretched polypropylene film are laminated in this order, with the transparent vapor deposition barrier film and the stretched nylon film being laminated via a layer made of the solvent-free adhesive; and winding up the laminate film into a roll, and then curing the rolled laminate film at 20 to 60°C for 12 hours or more, thereby curing the solvent-free adhesive.

[0023] According to one aspect of the present disclosure, it is possible to suppress the appearance defects that occur when a solventless adhesive is used to bond a transparent vapor-deposited barrier film and a stretched nylon film in the production of a packaging material. Also, according to another aspect of the present disclosure, it is possible to provide a packaging material in which the above-mentioned appearance defects are suppressed.

[0024] Fig. 1 is a schematic cross-sectional view showing a packaging material of one embodiment. Fig. 2 is a schematic cross-sectional view showing a laminated film used in manufacturing the packaging material shown in Fig. 1. Fig. 3 is a plan view showing a packaging bag of one embodiment.

[0025] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​written before and after "to" as the minimum and maximum values, respectively. Furthermore, unless specifically stated otherwise, the units of the numerical values ​​written before and after "to" are the same. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. Furthermore, the upper and lower limit values ​​individually described can be combined arbitrarily. Furthermore, "A or B" may include either A or B, or may include both.

[0026] <Packaging material and manufacturing method thereof> One embodiment of the present disclosure is a packaging material having a structure in which a transparent vapor deposition barrier film, a stretched nylon film, and an unstretched polypropylene film are laminated in this order, the transparent vapor deposition barrier film and the stretched nylon film are laminated via an adhesive layer made of a cured product of a solvent-free adhesive, and the ratio of Young's modulus in the MD direction of the unstretched polypropylene film to the thickness of the unstretched polypropylene film (MD Young's modulus / thickness) is 9.0 MPa / μm or more.

[0027] Another embodiment of the present disclosure is a method for producing the packaging material of the above embodiment, the method including: preparing a laminate film having a structure in which a transparent vapor deposition barrier film, a stretched nylon film, and an unstretched polypropylene film are laminated in this order, wherein the transparent vapor deposition barrier film and the stretched nylon film are laminated via a layer made of a solvent-free adhesive; and winding up the laminate film into a roll, and then curing the rolled laminate film at 20 to 60°C for 12 hours or more, thereby curing the solvent-free adhesive.

[0028] According to the method of the above embodiment, it is possible to suppress the poor appearance that occurs when a solventless adhesive is used to bond a transparent vapor-deposited barrier film and a stretched nylon film. Therefore, the packaging material of the above embodiment tends to have a good appearance. Specifically, for example, when the adhesive layer is observed from the stacking direction, the area ratio of air bubbles based on the area of ​​the adhesive layer is less than 1%. According to the method of the above embodiment, the area ratio of air bubbles can also be less than 0.5%. When multiple adhesive layers are present, the area of ​​all adhesive layers observed from the stacking direction is calculated by adding them together. However, when adhesive layers overlap each other, only the topmost adhesive layer is considered to be observed. The same applies to the area of ​​air bubbles.

[0029] The reason for this effect is unclear, but is presumed to be as follows. First, as mentioned above, the poor appearance that occurs when using a solventless adhesive is thought to be caused by factors such as the longer curing period required to cure the adhesive and the unevenness of the coating surface caused by the high viscosity of the adhesive, which can lead to air bubbles remaining between the films (particularly at the interface between the adhesive layer and the film). In contrast, when the laminated film is rolled and then cured, it is presumed that the pressure applied between the films causes compression between the films, which makes it easier for the air bubbles to pass through the film and escape to the outside. Furthermore, in the above method, the ratio (MD Young's modulus / thickness) of the unstretched polypropylene film is 9.0 MPa / μm or more, which increases the compression between the films and promotes the permeation of the air bubbles, thereby improving the appearance of the packaging material.

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate explanations will be omitted. The dimensional ratios of the drawings are not limited to those shown in the drawings.

[0031] (Packaging Material) Fig. 1 is a schematic cross-sectional view showing a packaging material of one embodiment. The packaging material 10 of Fig. 1 has a structure in which a transparent vapor-deposited barrier film 1, a stretched nylon film 2, and an unstretched polypropylene film 3 are laminated in this order. The transparent vapor-deposited barrier film 1 and the stretched nylon film 2 are laminated via a first adhesive layer S1, and the stretched nylon film 2 and the unstretched polypropylene film 3 are laminated via a second adhesive layer S2. The thickness of the packaging material 10 is, for example, 70 to 100 µm. The packaging material 10 is suitable for use in packages that are subjected to heat treatments such as retort treatment and boiling treatment (for example, heat sterilization treatment).

[0032] [Transparent vapor-deposited barrier film] The transparent vapor-deposited barrier film 1 is a functional film that has gas barrier properties such as water vapor barrier properties and oxygen barrier properties, and is also transparent to visible light. Here, gas barrier properties refer to the function of preventing gas permeation, and a film having water vapor barrier properties means that the film has water vapor barrier properties in accordance with JIS K7129-5 (2016) using a water vapor transmission rate measuring device (DELTAPERM manufactured by Technol ox) under conditions of 40°C and 90% relative humidity (WVTR, unit: g / m ２ / day) is 1.0 g / m ２ The term "oxygen barrier property" means that the film has oxygen barrier properties, which are measured in accordance with JIS K7126-2 (2006) using an oxygen transmission rate measuring device (OX-TRAN2 / 21 model manufactured by MOCON) under conditions of 25°C and 80% relative humidity (OTR, unit: cc / m ２ / day / atm) is 2cc / m ２ The term "transparent" means that the total light transmittance of the film is 85% or more as measured in accordance with JIS K7361-1:1997 using a color and turbidity simultaneous measuring device ("COH400" manufactured by Nippon Denshoku Industries Co., Ltd.).

[0033] From the viewpoint of protecting the vapor deposition layer from scratches during processing, the transparent vapor deposition barrier film 1 may have a structure in which a resin film, a transparent vapor deposition layer, and a protective layer are laminated in this order. A transparent vapor deposition barrier film having such a structure may be arranged so that the resin film is the outer layer (the side opposite to the stretched nylon film 2 side) and the protective layer is the inner layer (on the stretched nylon film 2 side).

[0034] Examples of resin materials constituting the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins such as polyethylene and polypropylene, polystyrene, polyamides such as nylon 66, polycarbonate, polyacrylonitrile film, polyimide, etc. The resin film may contain one of these materials alone or two or more of them.

[0035] The resin film may be a stretched film or a non-stretched film. The resin film may be a stretched film from the viewpoint of excellent mechanical strength and dimensional stability. The stretched film may be a uniaxially stretched film or a biaxially stretched film.

[0036] The surface of the resin film may be subjected to various pretreatments such as corona treatment, plasma treatment, and ozone treatment in order to improve adhesion to the transparent vapor deposition layer.

[0037] The thickness of the resin film can be changed as appropriate depending on the various resistances, processability, etc. required of the packaging material. The thickness of the resin film may be, for example, 3 to 200 μm, and from the viewpoint of increasing the flexibility of the packaging bag, may be 6 to 30 μm.

[0038] The transparent vapor deposition layer is a layer formed by vapor deposition of an inorganic material, such as a metal or metal oxide, that can provide gas barrier properties. Examples of inorganic materials include silicon oxide, aluminum oxide, and composites thereof. Vapor deposition of the inorganic material may be either physical vapor deposition or chemical vapor deposition. Vapor deposition methods include known vapor deposition methods such as vacuum deposition, sputtering, and chemical vapor deposition (CVD).

[0039] The thickness of the transparent vapor-deposited layer may be, for example, 10 to 50 nm, or 15 to 30 nm. The thicker the transparent vapor-deposited layer, the higher the barrier property, and the thinner the transparent vapor-deposited layer, the higher the transparency of the transparent vapor-deposited layer.

[0040] The protective layer is a layer formed of a material containing at least one selected from the group consisting of a condensate of a metal alkoxide, a condensate of a hydrolysis product of a metal alkoxide, and a condensate of an alkoxysilyl alkyl isocyanurate. The protective layer can be formed using a coating liquid obtained by mixing, for example, either a metal alkoxide or a hydrolysis product of a metal alkoxide, a polymer containing vinyl alcohol, an isocyanate compound, and a silane coupling agent.

[0041] Examples of metal alkoxides include alkoxysilanes such as tetraalkoxysilane, alkyltrialkoxysilane, and dialkyldialkoxysilane.

[0042] Examples of polymers containing vinyl alcohol include polyvinyl alcohol, polyvinyl acetate, and ethylene-vinyl acetate copolymer.

[0043] Examples of the isocyanate compound include aromatic isocyanate compounds such as tolylene diisocyanate and xylylene diisocyanate.

[0044] Examples of the silane coupling agent include an epoxy silane coupling agent, an amine silane coupling agent, a vinyl silane coupling agent, and an acrylic silane coupling agent.

[0045] The thickness of the protective layer may be, for example, 0.01 to 50 μm. When the thickness of the protective layer is 0.01 μm or more, the gas barrier properties of the protective layer can be improved. When the thickness of the protective layer is 50 μm or less, the occurrence of cracks in the protective layer can be suppressed.

[0046] The transparent vapor-deposited barrier film may have an anchor coat layer between the resin film and the transparent vapor-deposited layer for the purposes of improving adhesion between the resin film and the transparent vapor-deposited layer, improving gas barrier properties, etc.

[0047] The anchor coating layer may be a layer formed with a known anchor coating agent. Examples of anchor coating agents include various materials such as acrylic resins, epoxy resins, polyester resins, acrylic urethane resins, polyester urethane resins, polyether urethane resins, polyimide resins, melamine resins, phenolic resins, inorganic silica such as organically modified colloidal silica, and organic silane compounds such as silane coupling agents and their hydrolyzates. These materials may be used alone or as a mixture or composite. Furthermore, these materials may be used as a base agent in combination with any corresponding curing agent.

[0048] The thickness of the anchor coat layer may be, for example, 0.01 to 5 μm, 0.03 to 3 μm, or 0.05 to 2 μm.

[0049] A printed layer may be provided on the transparent vapor deposition barrier film 1. When the transparent vapor deposition barrier film 1 has a structure in which a resin film, a transparent vapor deposition layer, and a protective layer are laminated in this order, the printed layer may be disposed on the protective layer (on the side opposite to the transparent vapor deposition layer).

[0050] The print layer is an ink layer formed with one or more inks. Examples of inks that can be used include general gravure inks, flexographic inks, offset inks, and digital printing inks. These inks may be oil-based or water-based. Furthermore, the ink may be a colored ink containing a pigment and a binder resin, or a colorless ink containing a binder resin but no pigment. Known pigments and binder resins can be used as the pigment and binder resin depending on the application. When the ink is an oil-based gravure ink, examples of the binder resin include a mixture of a urethane resin and a vinyl chloride-vinyl acetate copolymer resin. The ink may contain various additives other than the pigment and binder resin, as well as a solvent (e.g., a volatile organic solvent). Examples of colored inks that can be used include vegetable oil inks and biomass inks.

[0051] The thickness of the printing layer is, for example, 0.2 to 8 μm.

[0052] Depending on the application, the transparent vapor deposition barrier film may have other functional layers such as an opacifying layer.

[0053] The transparent vapor-deposited barrier film 1 may have a thickness of, for example, 3 to 200 μm.

[0054] [Stretched Nylon Film] The stretched nylon film 2 is a stretched film containing nylon resin (polyamide resin) as a main component. The content of nylon resin in the stretched nylon film 2 is, for example, 90 mass % or more. The stretched nylon film 2 may be made only of nylon resin.

[0055] Examples of nylon resins include nylon 6, nylon 66, nylon 12, nylon 6,66 copolymer, nylon 6,12 copolymer, and metaxylene adipamide-nylon 6 copolymer.

[0056] In addition to the nylon resin, the stretched nylon film 2 may further contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent.

[0057] The stretched nylon film 2 may be a uniaxially stretched film or a biaxially stretched film.

[0058] The surface of the stretched nylon film 2 may be subjected to a surface activation treatment such as corona treatment, flame treatment, or plasma treatment.

[0059] The Young's modulus in the MD (Machine Direction) direction of the stretched nylon film 2 may be, for example, 2000 to 5000 MPa, 2200 to 4000 MPa, or 2400 to 3000 MPa, from the viewpoint of puncture resistance after lamination.

[0060] The Young's modulus in the TD (Transverse Direction) direction of the stretched nylon film 2 may be, for example, 1500 to 4500 MPa, 1900 to 3500 MPa, or 2200 to 3000 MPa.

[0061] The Young's modulus (MD direction and TD direction) of the stretched nylon film 2 can be measured in accordance with JIS K7127 using a tensile tester (for example, Orientec RTC-1250A). The test temperature specified in JIS K7127 is 23±2°C (recommended), and the "Young's modulus" in this specification is defined as the Young's modulus at 23°C. If the MD direction and TD direction of the stretched nylon film 2 in the packaging material 10 are unknown, they can be identified by the Young's modulus of the stretched nylon film 2. Since the Young's modulus of the stretched nylon film 2 usually exhibits the highest value in the MD direction, the direction exhibiting the highest Young's modulus is the MD direction, and the direction perpendicular to this is the TD direction.

[0062] The thickness of the stretched nylon film 2 may be 50 μm or less, 30 μm or less, or 20 μm or less, from the viewpoint of allowing air bubbles to easily pass through and making it easier to obtain a better appearance. The thickness of the stretched nylon film 2 may be 10 μm or more, from the viewpoint of obtaining sufficient strength (e.g., puncture strength). From the above viewpoint, the thickness of the stretched nylon film 2 may be, for example, 10 to 50 μm, 10 to 30 μm, or 10 to 20 μm. The thickness of the stretched nylon film 2 is the average value measured at any 10 points using a contact film thickness meter.

[0063] The ratio of the Young's modulus in the MD direction of the stretched nylon film 2 to the thickness of the stretched nylon film 2 (MD Young's modulus / thickness) may be, for example, 100 to 250 MPa / μm, 130 to 220 MPa / μm, or 150 to 200 MPa / μm, from the viewpoint of achieving both puncture strength and appearance.

[0064] [Non-stretched polypropylene film] The non-stretched polypropylene film 3 is a stretched film containing polypropylene resin as a main component. The content of polypropylene resin in the non-stretched polypropylene film 3 is, for example, 90 mass % or more. The non-stretched polypropylene film 3 may be made only of polypropylene resin.

[0065] The polypropylene resin may be a homopolymer of propylene or a copolymer of propylene and another copolymerizable monomer. Examples of copolymers include propylene-ethylene random copolymers, propylene-ethylene block copolymers, and propylene-α-olefin copolymers. The polypropylene resin may be an acid-modified polypropylene obtained by graft-modifying polypropylene with an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid, or the like.

[0066] In addition to polypropylene resin, the unstretched polypropylene film 3 may further contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent.

[0067] From the viewpoint of more easily obtaining a better appearance, the Young's modulus in the MD direction of the non-stretched polypropylene film 3 may be 450 MPa or more, 500 MPa or more, or 600 MPa or more. From the viewpoint of impact resistance, the Young's modulus in the MD direction of the non-stretched polypropylene film 3 may be 1200 MPa or less, 1000 MPa or less, or 800 MPa or less. From these viewpoints, the Young's modulus in the MD direction of the non-stretched polypropylene film 3 may be, for example, 450 to 1200 MPa, 500 to 1000 MPa, or 600 to 800 MPa.

[0068] The Young's modulus in the TD direction of the unstretched polypropylene film 3 may be, for example, 400 to 1000 MPa, 450 to 900 MPa, or 500 to 800 MPa.

[0069] The Young's modulus (MD direction and TD direction) of the unstretched polypropylene film 3 can be measured by the same method as that for the Young's modulus of a stretched nylon film. If the MD direction and TD direction of the unstretched polypropylene film 3 in the packaging material 10 are unknown, they can be identified by the Young's modulus of the unstretched polypropylene film 3. Since the unstretched polypropylene film 3 usually exhibits the highest Young's modulus in the MD direction, the direction exhibiting the highest Young's modulus is the MD direction, and the direction perpendicular to this is the TD direction.

[0070] The thickness of the non-stretched polypropylene film 3 may be 100 μm or less, 80 μm or less, or 60 μm or less, from the viewpoint of allowing air bubbles to easily pass through and making it easier to obtain a better appearance. The thickness of the non-stretched polypropylene film 3 may be 10 μm or more, from the viewpoint of stable heat seal strength development. From the above viewpoint, the thickness of the non-stretched polypropylene film 3 may be, for example, 10 to 100 μm, 10 to 80 μm, or 10 to 60 μm. The thickness of the non-stretched polypropylene film 3 is an average value measured at any 10 points using a contact film thickness meter.

[0071] The ratio of the Young's modulus in the MD direction of the non-stretched polypropylene film 3 to the thickness of the non-stretched polypropylene film 3 (MD Young's modulus / thickness) is 9.0 MPa / μm or more, and from the viewpoint of more easily obtaining a better appearance, it may be 10.0 MPa / μm or more or 11.0 MPa / μm or more. From the viewpoint of low-temperature heat sealability, the ratio of the Young's modulus in the MD direction of the non-stretched polypropylene film 3 to the thickness of the non-stretched polypropylene film 3 (MD Young's modulus / thickness) may be 18.0 MPa / μm or less, 17.0 MPa / μm or less, or 16.0 MPa / μm or less. From the above viewpoint, the ratio of the Young's modulus in the MD direction of the non-stretched polypropylene film 3 to the thickness of the non-stretched polypropylene film 3 (MD Young's modulus / thickness) may be, for example, 9.0 to 18.0 MPa / μm, 10.0 to 17.0 MPa / μm, or 11.0 to 16.0 MPa / μm.

[0072] [Adhesive Layer] The adhesive layers (first adhesive layer S1 and second adhesive layer S2) are made of a cured product of a solventless adhesive. As the solventless adhesive, a polyurethane-based adhesive containing a polyisocyanate component and a polyol component may be used from the viewpoints of cost, hygiene, and processability. The polyurethane-based adhesive may be a two-component curing adhesive in which the polyisocyanate component and the polyol component are mixed at the time of use, or may be a one-component curing adhesive in which the polyisocyanate component and the polyol component are mixed in advance.

[0073] The polyisocyanate component may be a polyisocyanate monomer or a polyisocyanate derivative, and may contain one of these alone or two or more of these.

[0074] From the viewpoint of ease of procurement, the polyisocyanate monomer may be a diisocyanate. The diisocyanate may be an aliphatic diisocyanate such as hexamethylene diisocyanate (HDI), an alicyclic diisocyanate such as isophorone diisocyanate (IPDI), an araliphatic diisocyanate such as xylylene diisocyanate (XDI), or an aromatic diisocyanate such as methylenebis(4,1-phenylene)diisocyanate (MDI).

[0075] The polyisocyanate derivative is a compound derived from the above polyisocyanate monomer. The polyisocyanate derivative may be a polymer (e.g., dimer, trimer, pentamer, etc.) of the polyisocyanate monomer, a biuret, an adduct, an allophanate, etc. The polyisocyanate derivative may also be an isocyanate-terminated prepolymer derived from the above polyisocyanate monomer.

[0076] The isocyanate-terminated prepolymer is a compound obtained, for example, by subjecting a polyisocyanate (a polyisocyanate monomer or a polyisocyanate derivative) to a urethanization reaction with a polyol (particularly a diol) described below, in such a manner that the equivalent ratio (NCO / OH) of the isocyanate groups of the polyisocyanate to the hydroxyl groups of the polyol is greater than 1.

[0077] The polyisocyanate component may contain an aliphatic diisocyanate or a derivative thereof, and an aromatic diisocyanate or a derivative thereof from the viewpoint of increasing adhesive strength, and may contain HDI or a derivative thereof, IPDI or a derivative thereof, and XDI or a derivative thereof from the viewpoint of food hygiene.

[0078] Examples of the polyol component include polyester polyol, polyether polyol, polyether ester polyol, and polyurethane polyol. The polyol component may contain one of these alone or two or more of these. The polyol component may be partially acid-modified at the terminal so that the valence is 2 to 20.

[0079] The polyol component may contain a polyester polyol from the viewpoint of heat resistance. The polyester polyol may be, for example, an ester reaction product obtained by reacting a polycarboxylic acid, a dialkyl ester of a polycarboxylic acid, or a mixture thereof with a glycol-based compound. Examples of polycarboxylic acids include succinic acid, glutaric acid, isophthalic acid, terephthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimer acid. Examples of glycol-based compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 2-methyl-1,3-propanediol, butylene glycol, neopentyl glycol, and 1,6-hexanediol. The use of aromatic carboxylic acids such as isophthalic acid and terephthalic acid is expected to improve heat resistance. Furthermore, the use of glycols having an ether moiety such as diethylene glycol, triethylene glycol, and dipropylene glycol, or glycols having a branched structure such as propylene glycol and 2-methyl-1,3-propanediol, can suppress the viscosity of the adhesive, making it easier to apply the adhesive and is expected to suppress bubbles and poor appearance.

[0080] The polyol component may contain a polyether polyol, which has a lower viscosity than a polyester polyol, in order to reduce the viscosity of the adhesive. By reducing the viscosity of the adhesive, it is possible to easily apply the adhesive and to reduce the occurrence of bubbles and poor appearance.

[0081] The combination of polyisocyanate and polyol may be HDI or a derivative thereof and a polyester polyol, or IPDI or a derivative thereof and a polyester polyol from the viewpoints of food hygiene and heat resistance, or XDI or a derivative thereof and a polyester polyol from the viewpoint of rapid curing.

[0082] The basis weight of the adhesive layers (first adhesive layer S1 and second adhesive layer S2) is, for example, 0.5 to 3.0 g / m ２ and may be 1.0 to 2.0 g / m ２ may be.

[0083] (Laminate Film) Figure 2 is a schematic cross-sectional view showing a laminate film used in producing the packaging material 10 shown in Figure 1. The laminate film 20 has a structure in which a transparent vapor-deposited barrier film 1, a stretched nylon film 2, and an unstretched polypropylene film 3 are laminated in this order. The transparent vapor-deposited barrier film 1 and the stretched nylon film 2 are laminated via a first uncured layer S'1, and the stretched nylon film 2 and the unstretched polypropylene film 3 are laminated via a second uncured layer S'2. The first uncured layer S'1 and the second uncured layer S'2 are layers made of a solventless adhesive, and become the first adhesive layer S1 and the second adhesive layer S2, respectively, when cured.

[0084] The laminate film 20 includes, for example, a step of bonding one surface of a transparent vapor deposition barrier film 1 to one surface of a stretched nylon film 2 via a first uncured layer S'1 (first laminating step), and a step of bonding one surface of the stretched nylon film 2 (the surface opposite to the surface bonded to the transparent vapor deposition barrier film 1) to one surface of an unstretched polypropylene film 3 via a second uncured layer S'2 (second laminating step). The order of the first laminating step and the second laminating step is not particularly limited, and the second laminating step may be performed after the first laminating step, or the first laminating step may be performed after the second laminating step.

[0085] In the first laminating step, the first uncured layer S'1 may be formed by applying a solvent-free adhesive to one surface (e.g., the surface on the protective layer side) of the transparent vapor deposition barrier film 1, or the first uncured layer S'1 may be formed by applying a solvent-free adhesive to one surface of the stretched nylon film 2. In the former case, one surface of the stretched nylon film 2 may be bonded to the surface of the transparent vapor deposition barrier film 1 on which the first uncured layer S'1 is formed, and in the latter case, one surface of the transparent vapor deposition barrier film 1 may be bonded to the surface of the stretched nylon film 2 on which the first uncured layer S'1 is formed.

[0086] In the second laminating step, the second uncured layer S'2 may be formed by applying a solvent-free adhesive to one surface of the stretched nylon film 2 (the surface opposite to the surface to be bonded to the transparent vapor deposition barrier film 1), or the second uncured layer S'2 may be formed by applying a solvent-free adhesive to one surface of the unstretched polypropylene film 3. In the former case, one surface of the unstretched polypropylene film 3 may be bonded to the surface of the stretched nylon film 2 on which the second uncured layer S'2 is provided, and in the latter case, one surface of the stretched nylon film 2 (the surface opposite to the surface to be bonded to the transparent vapor deposition barrier film 1) may be bonded to the surface of the unstretched polypropylene film 3 on which the first uncured layer S'1 is provided.

[0087] The application of the solventless adhesive in the first and second lamination steps can be carried out using, for example, a roll coater, bar coater, spray coater, gravure coater, curtain coater, etc. The application speed may be, for example, 50 to 300 m / min. When using a roll coater, the application speed can be adjusted by the conveyance speed of the film to be coated. The temperature of the solventless adhesive during application may be, for example, 40 to 100°C. The viscosity of the solventless adhesive during application (viscosity at the application temperature) may be, for example, 50 to 3000 mPa·s. Here, the viscosity of the solventless adhesive is the cone-plate viscosity in accordance with JIS K 5600-2-2:2014.

[0088] The lamination in the first and second lamination steps can be performed using a non-solvent laminator. The lamination temperature may be, for example, 20 to 70°C. The lamination speed may be, for example, 50 to 300 m / min. The faster the lamination speed, the more likely it is that poor appearance will occur, but in the method of this embodiment, a good appearance can be obtained even if the lamination speed is 100 m / min or more (for example, 150 to 250 m / min).

[0089] (Method for manufacturing packaging material) The method for manufacturing packaging material 10 includes preparing laminate film 20 shown in FIG. 2, winding laminate film 20 into a roll, and then curing roll-shaped laminate film 20 at 20 to 60° C. for 12 hours or more to harden the solventless adhesive.

[0090] In the method for manufacturing the packaging material 10, a pre-fabricated laminate film 20 may be prepared, or the laminate film 20 may be produced by the method described above.

[0091] The laminate film 20 can be wound up using, for example, a known winding device. The winding tension (tension applied to the laminate film 20) when winding the laminate film 20 may be, for example, 100 to 300 N / m. The radius of the roll of laminate film 20 obtained after winding may be, for example, 30 to 130 cm.

[0092] The curing temperature of the laminated film 20 is 20 to 60° C., and may be 25 to 55° C. or 35 to 50° C. The curing time of the laminated film 20 is 12 hours or more, and may be, for example, 12 to 148 hours, 24 to 120 hours, or 48 to 96 hours.

[0093] <Packaging Bag> Another embodiment of the present disclosure is a packaging bag produced from the packaging material of the above embodiment.

[0094] 3 is a plan view showing a packaging bag of one embodiment. The packaging bag 30 is obtained by processing the packaging material 10 into a bag shape. The packaging bag 30 is obtained by overlapping a pair of packaging materials 10 so that the surfaces of the unstretched polypropylene films 3 face each other, or by folding one packaging material 10 so that the surfaces of the unstretched polypropylene films 3 face each other, and then heat-sealing the peripheral edges L1, L2, and L3 of the overlapped packaging materials.

[0095] The packaging bag 30 has an opening 30a that is not heat-sealed. An object is placed inside the packaging bag 30 through the opening 30a, and the opening 30a is heat-sealed to hermetically seal the packaging bag 30, thereby obtaining a package comprising the packaging bag 30 and the contents. The object (content) placed in the packaging bag 30 is not particularly limited and may be a solid, a liquid, or a mixture thereof. Examples of the contents include food, beverages, medicines, electronic devices, etc.

[0096] The packaging bag is suitable for use in packaging that is to be subjected to a heat treatment such as retort treatment or boiling treatment (for example, heat sterilization treatment).

[0097] The packaging material, the manufacturing method thereof, and the package according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments.

[0098] For example, the packaging material may have a transparent vapor-deposited barrier film, a film made of oriented nylon film and unoriented polypropylene film, and an adhesive layer other than the first adhesive layer and the second adhesive layer. For example, the packaging material may have a film provided with a printed layer (a film with a printed layer). The film with a printed layer is not particularly limited, but may have transparency so that a picture on the printed layer can be displayed. The packaging material may also have a film with other functional layers such as a concealing layer. The film with a printed layer may have the other functional layer. The details of the printed layer are the same as those described above.

[0099] The second adhesive layer of the packaging material may be formed of a solvent-based adhesive. As the solvent-based adhesive, a known dry lamination adhesive (e.g., a urethane-based adhesive) used in this technical field can be used. When a solvent-based adhesive is used to form the second adhesive layer, a laminated film can be obtained in the same manner as when a solventless adhesive is used, except that a step of drying the adhesive is performed after application of the adhesive.

[0100] The second uncured layer in the laminated film may also be the second adhesive layer.

[0101] The packaging bag may be in the form of, for example, pillow packaging, three-side seal packaging, gusset packaging, or the like.

[0102] The present disclosure will be described below based on examples and comparative examples, but the present disclosure is not limited to the following examples.

[0103] <Preparation of Materials> The following materials were prepared.

[0104] [Transparent vapor-deposited barrier film with printed layer] A transparent vapor-deposited barrier film manufactured by Toppan Printing Co., Ltd. (product name "GL-PET #12", a film having a structure in which a 0.01 nm-thick vapor-deposited alumina layer and a 0.3 μm-thick protective layer (polyvinyl alcohol and a silane coupling agent) are laminated in this order on a 12 μm-thick PET film) was prepared. A printed layer (thickness: 1.2 μm) made of colored ink was formed by gravure printing on the laminate surface (surface of the protective layer) of this transparent vapor-deposited barrier film. The colored ink used was "Lio Alpha White" manufactured by Toyo Ink Co., Ltd., and the printing was carried out so that the printed areas made of colored ink (white ink) and plain areas without ink formed a checkerboard pattern. Through the above operations, a transparent vapor-deposited barrier film with a printed layer was obtained.

[0105] [Stretched nylon film] ONMB-RT manufactured by Unitika Ltd. (thickness: 15 μm, Young's modulus in MD direction: 2500 MPa, Young's modulus in TD direction: 2300 MPa)

[0106] [Unstretched Polypropylene Film] Unstretched polypropylene films shown in Table 1 below

[0107] [Solvent-free adhesive] A two-component curing urethane-based solvent-free adhesive containing the following polyol component and the following polyisocyanate component in an equivalent ratio of 1:1: Polyol component: "TSN-4864A" (polyester polyol) manufactured by Toyo-Morton Co., Ltd. Polyisocyanate component: "TSN-4864B-3" (polyisocyanate mixture containing HDI and IPDI) manufactured by Toyo-Morton Co., Ltd.

[0108] Example 1 The transparent vapor-deposited barrier film with the printed layer and the stretched nylon film were laminated together by a non-solvent lamination method using the solvent-free adhesive to obtain a first laminated film. ２The adhesive was applied to the laminate surface (on the surface of the protective layer on which the printed layer was formed) of the transparent vapor-deposited barrier film with a printed layer so that the adhesive temperature during application was 80°C, the cone-plate viscosity of the adhesive during application was 430 mPa s, the adhesive application speed and lamination speed were 150 m / min, the lamination temperature was 50°C, and the coating distance was 400 m. The laminated film obtained after lamination was wound into a roll using a 3-inch core.

[0109] The first laminated film obtained above and a CPP film 1, which is an unstretched polypropylene film, were laminated together by a non-solvent lamination method using the solvent-free adhesive to obtain a second laminated film. ２ The adhesive was applied to an unstretched polypropylene film so that the thickness of the first laminated film was 1 / 4 of the original thickness. The first laminated film was arranged so that the stretched nylon film was the inner layer and the transparent vapor-deposited barrier film was the outer layer. The adhesive temperature during application was 80°C, the cone-plate viscosity of the adhesive during application was 430 mPa·s, the adhesive application speed and lamination speed were 200 m / min, the lamination temperature was 50°C, and the coating distance was 300 m. The laminated film obtained after lamination was wound into a roll using a 3-inch core.

[0110] The second laminate film was taken up into a roll, and then the rolled second laminate film was cured for 72 hours at 40° C. to cure the solventless adhesive. This resulted in a packaging material having a structure in which a transparent vapor-deposited barrier film with a printing layer, a stretched nylon film, and an unstretched polypropylene film were laminated in this order via adhesive layers (first adhesive layer and second adhesive layer) made of the cured product of the solventless adhesive.

[0111] Examples 2 to 7 and Comparative Examples 1 to 5 Packaging materials of Examples 2 to 7 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that the films shown in Table 2 were used as the unstretched polypropylene films.

[0112] <Appearance Evaluation> The appearance was evaluated by the following method. A sample was taken from a point 5 m from the outside of the roll of the resulting packaging material wound into a roll, and images of the printed and plain areas of the packaging material were taken from the CPP surface at a magnification of 50x using a microscope (product name "VHX-6000": manufactured by Keyence Corporation). The images obtained were then binarized, and the area ratio of the bubble portion to the total area of ​​the observed image was measured as a result of quantitative observation and classified according to the following criteria. [Evaluation criteria] ◎: Bubble area ratio less than 0.5% ○: Bubble area ratio 0.5% or more but less than 1.0% △: Bubble area ratio 1.0% or more but less than 2.0% ×: Bubble area ratio 2.0% or more

[0113]

[0114] 1...transparent vapor-deposited barrier film, 2...stretched nylon film, 3...unstretched polypropylene film, 10...packaging material, 20...laminated film, 30...packaging bag, 30a...opening, S1...first adhesive layer, S2...second adhesive layer, S'1...first uncured layer, S'2...second uncured layer.

Claims

1. A packaging material having a structure in which a transparent vapor deposition barrier film, a stretched nylon film, and an unstretched polypropylene film are laminated in this order, wherein the transparent vapor deposition barrier film and the stretched nylon film are laminated via an adhesive layer composed of a cured product of a solventless adhesive, and the ratio of the Young's modulus in the MD direction of the unstretched polypropylene film to the thickness of the unstretched polypropylene film is 9.0 MPa / μm or more.

2. The packaging material according to claim 1, wherein the Young's modulus in the MD direction of the unstretched polypropylene film is 450 MPa or more.

3. The packaging material according to claim 1, wherein the Young's modulus in the MD direction of the unstretched polypropylene film is 1200 MPa or less.

4. The packaging material according to claim 1, wherein the thickness of the unstretched polypropylene film is 100 μm or less.

5. The packaging material according to claim 1, wherein the thickness of the unstretched polypropylene film is 10 μm or more.

6. The packaging material according to claim 1, wherein the ratio of the Young's modulus in the MD direction of the unstretched polypropylene film to the thickness of the unstretched polypropylene film is 18.0 MPa / μm or less.

7. The packaging material according to claim 1, wherein the ratio of the Young's modulus in the MD direction of the stretched nylon film to the thickness of the stretched nylon film is 100 to 250 MPa / μm.

8. The packaging material according to claim 1, wherein the Young's modulus in the MD direction of the stretched nylon film is 2000 to 5000 MPa.

9. The packaging material according to claim 1, wherein the thickness of the stretched nylon film is 50 μm or less.

10. The packaging material according to claim 1, wherein the transparent vapor deposition barrier film has a structure in which a resin film, a transparent vapor deposition layer, and a protective layer are laminated in this order, and the resin film is arranged as the outer layer and the protective layer is arranged as the inner layer.

11. The packaging material according to claim 1, wherein the solventless adhesive is a polyurethane-based adhesive containing a polyisocyanate component and a polyol component.

12. The packaging material according to claim 1, wherein the stretched nylon film and the unstretched polypropylene film are laminated via an adhesive layer composed of a cured product of a solventless adhesive.

13. The packaging material according to claim 1, wherein the area ratio of bubbles based on the area of the adhesive layer when observing the adhesive layer from the lamination direction is less than 1%.

14. A packaging bag formed by bagging the packaging material according to any one of claims 1 to 13.

15. A method for manufacturing a packaging material according to any one of claims 1 to 13, comprising: preparing a laminated film having a structure in which the transparent vapor-deposited barrier film, the stretched nylon film, and the non-stretched polypropylene film are laminated in this order, and the transparent vapor-deposited barrier film and the stretched nylon film are laminated via a layer made of the solventless adhesive; and curing the solventless adhesive by curing the laminated film wound in a roll shape at 20 to 60 ° C for 12 hours or more.

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