Resin film for packaging, laminate for packaging, and package

Abstract

To improve airtightness of a package formed of a laminate including a resin film.SOLUTION: A resin film for package 10 used for formation of a gas barrier layer 11 contains polyethylene terephthalate, polyethylene terephthalate contains recycled PET which is at least one of PET recycled by mechanical recycling and PET recycled by chemical recycling, contains a terephthalic acid component, an isophthalic acid component, and a naphthalenedicarboxylic acid component as a dicarboxylic acid component of polyester, When the total amount of the above components, an ethylene glycol component contained as a diol component, and a diethylene glycol component is 100 mol%, the molar ratio of the isophthalic acid component to the total amount is 2×10-1 mol% or more and 9×10-1 mol% or less, and the molar ratio of the naphthalenedicarboxylic acid component is 1×10-2 mol% or more and 6×10-2 mol% or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a resin film for packaging. [Background technology]

[0002] Resin films containing polyethylene terephthalate are widely used as packaging materials for packaging contents such as food, medicines, and cosmetics. In general, these resin films have the property of slightly allowing gases such as oxygen and hydrogen to pass through. For this reason, a laminate of a resin film and a gas barrier layer including a metal film or a metal oxide film is used as a packaging material (see, for example, Patent Document 1). In addition, it is desirable for the resin film itself to be made of a material with high gas barrier properties, which means that the material of the resin film has the property of being difficult for gases to pass through. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-81607 A Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, during the distribution process of a product whose contents are packaged in a package made of a laminate of a resin film and a gas barrier layer, external forces that cause deformation such as friction and bending are repeatedly applied to the product. When external forces are repeatedly applied to the package in this way, cracks are formed in the gas barrier layer, and the airtightness of the package is lost. Therefore, the laminate is required to comprehensively improve the airtightness of the package by not only improving the gas barrier property but also increasing the resistance to deformation. [Means for solving the problem]

[0005] The laminate for packaging that solves the above-mentioned problems is a laminate for packaging, comprising a resin film and a gas barrier layer laminated on the resin film, the resin film comprising a terephthalic acid component, an isophthalic acid component, and a naphthalenedicarboxylic acid component as a polyester dicarboxylic acid component, and a molar ratio of the isophthalic acid component to the total amount of the dicarboxylic acid component and the diol component is 2×10 -1 mol% or more 9×10 -1 mol% or less, and the molar ratio of the naphthalenedicarboxylic acid component is 1×10 -2 mol% or more 6×10 -2 It is less than mol%.

[0006] The resin film for packaging that solves the above-mentioned problems is a resin film that constitutes a laminate for packaging bags by laminating a gas barrier layer having gas barrier properties, the resin film containing a terephthalic acid component, an isophthalic acid component, and a naphthalenedicarboxylic acid component as polyester dicarboxylic acid components, and the molar ratio of the isophthalic acid component to the total amount of the dicarboxylic acid component and the diol component is 2×10 -1 mol% or more 9×10 -1 mol% or less, and the molar ratio of the naphthalenedicarboxylic acid component is 1×10 -2 mol% or more 6×10 -2 It is less than mol%.

[0007] The package that solves the above-mentioned problem is a package including a laminate, the laminate including a resin film and a gas barrier layer laminated on the resin film, the laminate including a terephthalic acid component, an isophthalic acid component, and a naphthalenedicarboxylic acid component as dicarboxylic acid components of a polyester, the molar ratio of the isophthalic acid component to the total amount of the dicarboxylic acid component and the diol component being 2×10 -1 mol% or more 9×10 -1 mol% or less, and the molar ratio of the naphthalenedicarboxylic acid component is 1×10 -2 mol% or more 6×10 -2 It is less than mol%.

[0008] According to the above configuration, since the molar ratio of the isophthalic acid component is within the above range, the flexibility of the resin film is enhanced. By increasing the flexibility of the resin film, the resin film is more likely to absorb the load applied to the laminate, so that the load applied to the gas barrier layer is reduced and the bending resistance is improved. In addition, since the molar ratio of the naphthalene dicarboxylic acid component is within the above range, the plane orientation coefficient of the resin film can be increased. By increasing the plane orientation coefficient, the gas barrier property of the resin film itself can be improved and the adhesion with the gas barrier layer can be improved. Therefore, the airtightness of the laminate in which the gas barrier layer is laminated can be comprehensively improved.

[0009] In the laminate for packaging, the molar ratio of the isophthalic acid component to the total amount of the dicarboxylic acid component and the diol component is 5×10 -1 mol% or more 9×10 -1 The molar ratio of the naphthalenedicarboxylic acid component is 4×10 or less. -2 mol% or more 6×10 -2 It may be the following. According to the above-mentioned configuration, the airtightness of the laminate for packaging in which the gas barrier layer is laminated can be further improved comprehensively. In the laminate for packaging, the gas barrier layer may include a coating that contains at least one of aluminum oxide and silicon oxide and is in contact with the surface of the resin film. According to the above-mentioned configuration, a coating having transparency can be formed on the resin film. In addition, the gas barrier properties of the laminate can be improved by reducing the water vapor permeability and oxygen permeability of the gas barrier layer. In addition, the adhesion between the resin film and the first coating containing at least one of aluminum oxide and silicon oxide can be ensured.

[0010] In the laminate for packaging, the gas barrier layer is made of Si(OR 1 )4, or R 2 Si(OR 3 )3(OR 1 and OR 3 is a hydrolyzable group, R 2is an organic functional group) or one or more types of hydrolyzates of silicon compounds, and a water-soluble polymer having a hydroxyl group.

[0011] According to the above-mentioned configuration, the water vapor permeability and oxygen permeability of the gas barrier layer are reduced, so that the gas barrier properties of the laminate can be further improved. Effect of the Invention

[0012] According to the present invention, it is possible to comprehensively improve the airtightness of a package comprising a laminate including a resin film. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram showing a cross-sectional structure of a resin film according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a cross-sectional structure of a laminate according to an embodiment. [Diagram 3] FIG. 2 is a perspective view showing a packaging body according to an embodiment; [Figure 4] 1H-NMR spectrum of the example. [Diagram 5] An enlarged view of a portion of the 1H-NMR spectrum in Figure 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of a laminate for a packaging body, a packaging body, and a resin film for a packaging body will be described with reference to the drawings. [Resin film] The structure of a resin film 10, which is a resin film for packaging, will be described with reference to FIG. 1. The resin film 10 is made of polyester and contains polyethylene terephthalate (PET). The PET resin is at least one of virgin PET newly synthesized from raw materials such as petroleum, and recycled PET, which is recycled PET resin. PET products that are subject to recycling include used PET bottles. The recycled PET constituting the resin film 10 is at least one of PET recycled by mechanical recycling and PET recycled by chemical recycling.

[0015] Mechanical recycling includes a process of crushing PET products into resin fragments, a process of washing the resin fragments to remove surface dirt and foreign matter, and a process of exposing the resin fragments to high temperatures to remove contaminants remaining inside the resin. Chemical recycling includes a process of crushing PET products into resin fragments, a process of washing the resin fragments to remove surface dirt and foreign matter, a process of returning the resin to an intermediate raw material by depolymerization, and a process of purifying the intermediate raw material and repolymerizing it. Mechanical recycling does not require large-scale equipment for chemical reactions compared to chemical recycling, so the cost required for manufacturing recycled PET can be reduced. In addition, it reduces carbon dioxide emissions, so the burden on the environment is small. In order to reduce costs and the burden on the environment, it is preferable that the recycled PET used as the raw material for the resin film 10 is PET regenerated by mechanical recycling.

[0016] When the resin film 10 contains virgin PET in addition to recycled PET, the proportion of recycled PET is preferably 60% by weight or more and 100% by weight or less of the resin film 10, from the viewpoint of reducing costs and environmental impact.

[0017] The polyester constituting the resin film 10 contains a terephthalic acid component, an isophthalic acid component, and a naphthalenedicarboxylic acid component as a dicarboxylic acid component, which is a repeating unit. The naphthalenedicarboxylic acid component is a polycarboxylic acid component having a naphthalene skeleton, and examples of the naphthalenedicarboxylic acid include 2,6-naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid. Note that the polyester may contain 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid.

[0018] The isophthalic acid component and the naphthalenedicarboxylic acid component may be derived from recycled PET or from virgin PET. Or, they may be added at any step of the manufacturing process. Furthermore, a dicarboxylic acid component such as adipic acid, and a glycol component such as propylene glycol, 1,4-butanediol, tetramethylene glycol, neopentyl glycol, cyclohexanedimethanol, and diethylene glycol may be included. Generally, PET resin is produced by polymerizing terephthalic acid, which is a dicarboxylic acid, and ethylene glycol, which is a diol, but the PET resin used in the resin film 10 is a resin produced by copolymerizing terephthalic acid with isophthalic acid and naphthalenedicarboxylic acid, or a resin produced by copolymerizing terephthalic acid with isophthalic acid and mixing polyethylene naphthalate resin with polyethylene terephthalate resin. In other words, the isophthalic acid component and the naphthalenedicarboxylic acid component may be included as a copolymerization component with polyethylene terephthalate, or may be included as a polyester separate from polyethylene terephthalate.

[0019] The average molecular weight of the PET resin contained in the resin film 10 is not particularly limited, but is preferably, for example, about 1,000 to 1,000,000. The resin film 10 may contain resins other than PET and various additives such as plasticizers.

[0020] The resin film 10 is composed of a single layer or multiple layers. When the resin film 10 is composed of multiple layers, the materials constituting each layer may be the same or different. An example of a configuration in which the materials constituting each layer are different from each other is a laminate of a layer formed from recycled PET and a layer formed from virgin PET. Another example of a configuration in which the materials constituting each layer are different from each other is a laminate of a layer containing recycled PET at a first ratio to virgin PET and a layer containing recycled PET at a second ratio to virgin PET that is different from the first ratio.

[0021] The thickness of the resin film 10 is selected according to various properties required for the package, such as various environmental resistances such as heat and moisture, storage stability of the contents, filling stability of the contents, sealing processability, printing resistance including marking, etc. From the viewpoint of improving the processability of the resin film 10, for example, the thickness of the resin film 10 is preferably selected from the range of 3 μm to 100 μm, and more preferably selected from the range of 6 μm to 50 μm.

[0022] The method for forming the resin film 10 is a melt extrusion method or a melt coextrusion method. The flow direction of the resin film 10 is the direction in which the molding of the PET resin proceeds during the production of the resin film 10. The flow direction is also called the MD (Machine Direction) direction or the longitudinal direction. The direction perpendicular to the flow direction is also called the TD (Transverse Direction) direction or the lateral direction. When the resin film 10 is composed of multiple layers, the flow direction of each layer is the same.

[0023] The resin film 10 is a non-stretched film, a uniaxially stretched film stretched in the MD or TD at a predetermined ratio, or a biaxially stretched film stretched in the MD and TD at a predetermined ratio either sequentially or simultaneously. When the resin film 10 is composed of multiple layers, the stretching direction of each layer is the same.

[0024] [Laminate] A laminate 20, which is a laminate for packaging, will be described with reference to Fig. 2. The laminate 20 includes a resin film 10 and a gas barrier layer 11. The gas barrier layer 11 has a function of enhancing the gas barrier properties of the laminate 20. Note that the ratio of the thickness of the resin film 10 to the thickness of the gas barrier layer 11 is not limited to the ratio shown in Fig. 2.

[0025] The gas barrier layer 11 includes a vapor-deposited film formed by, for example, chemical vapor deposition or physical vapor deposition. The vapor-deposited film is an inorganic oxide film or a metal film. The inorganic substance contained in the inorganic oxide may be, for example, an oxide of silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, yttrium, or the like. The metal may be, for example, aluminum, magnesium, tin, sodium, titanium, lead, zirconium, yttrium, gold, chromium, or the like.

[0026] The method for forming the vapor-phase deposition film may be, for example, a vacuum deposition method, a sputtering method, an ion plating method, or a plasma vapor deposition method (CVD). From the viewpoint of increasing the productivity of the laminate, the method for forming the vapor-phase deposition film is preferably a vacuum deposition method. In the vacuum deposition method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method as a method for heating the deposition material. From the viewpoint of increasing the degree of freedom in the selection of the deposition material, it is preferable to use an electron beam heating method. From the viewpoint of increasing the adhesion between the vapor-phase deposition film and the resin film 10 and from the viewpoint of increasing the density of the vapor-phase deposition film, it is possible to use a plasma assist method and an ion beam assist method in the vacuum deposition method. From the viewpoint of increasing the transparency of the deposition layer, the gas barrier layer 11 may be formed by a reactive deposition method. In the reactive deposition method, a reactive gas such as oxygen gas is supplied to the film formation space.

[0027] The laminate 20 for forming a transparent package includes a vapor-phase deposited film formed from an inorganic oxide. In particular, vapor-phase deposited films formed from aluminum oxide and silicon oxide are preferred. The laminate 20 for forming a package having light-shielding properties includes a vapor-phase deposited film formed from a metal. In particular, a vapor-phase deposited film formed from aluminum is preferred.

[0028] The gas barrier layer 11 may be formed of a plurality of barrier layers. In this case, each barrier layer may be formed of the same material, or the plurality of barrier layers may include a barrier layer formed of a first material and a barrier layer formed of a second material different from the first material.

[0029] The thickness of the gas barrier layer 11 is not particularly limited, but in the case of a vapor-phase deposition film, it is, for example, 5 nm or more and 300 nm or less. When the thickness of the gas barrier layer 11 is 5 nm or more, the uniformity of the gas barrier layer 11 can be increased and the gas barrier layer 11 can have a sufficient thickness. Therefore, the gas barrier layer 11 can fully exhibit the gas barrier function. On the other hand, when the thickness is 300 nm or less, the gas barrier layer 11 can maintain flexibility. This suppresses cracks in the gas barrier layer 11 caused by external factors such as bending and pulling after film formation. The thickness of the gas barrier layer 11 is appropriately selected depending on the type of inorganic compound forming the gas barrier layer 11 and the configuration of the laminate 20. From the viewpoint of increasing the uniformity in the thickness of the gas barrier layer 11, it is more preferable that the thickness of the gas barrier layer 11 is included in the range of 10 nm or more and 150 nm or less.

[0030] The gas barrier layer 11 may include a coating film having gas barrier properties in addition to or instead of the above-mentioned vapor-phase deposited film. The coating film is made of a material containing a resin. The coating film protects the vapor-phase deposited film, and thus the gas barrier properties of the gas barrier layer can be improved.

[0031] The coating film is formed, for example, from a water-soluble polymer and an inorganic compound. The water-soluble polymer may be, for example, polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. From the viewpoint of improving the gas barrier properties of the gas barrier layer 11, it is preferable that the water-soluble polymer is polyvinyl alcohol (PVA).

[0032] The inorganic compound contained in the coating film is, for example, Si(OR 1 )4 or R 2 Si(OR 3 In addition, the silicon compound may be a silicon compound represented by the formula OR 1 and OR 3 is a hydrolyzable group, R 2 is an organic functional group. The inorganic compound may include one or more silicon compounds or hydrolysates of such silicon compounds.

[0033] Si(OR 1 For example, R may be tetraethoxysilane (Si(OC2H5)4) (TEOS). TEOS is preferred because it is relatively stable in aqueous solvents after hydrolysis. 2 Si(OR 3 )3 contains R 2 is preferably selected from the group consisting of a vinyl group, an epoxy group, a methacryloxy group, a ureido group, and an isocyanate group.

[0034] The coating film is formed by applying a mixed solution of a solvent, a water-soluble polymer, and a silicon compound or a hydrolyzate of a silicon compound onto a deposition layer, followed by heating and drying. The solvent may be water or a mixed solvent of water and alcohol. When forming the mixed solution, first, the water-soluble polymer is dissolved in a solvent, and then the silicon compound or a hydrolyzate of a silicon compound is mixed. The mixed solution may contain additives within a range in which the coating film formed using the mixed solution does not impair the gas barrier properties. The additives may be, for example, an isocyanate compound, a silane coupling agent, a dispersant, a stabilizer, a viscosity modifier, and a colorant.

[0035] When the water-soluble polymer is PVA, the ratio of PVA to the mass (mol) of the total solid content of the mixed solution is preferably 20 mol% to 50 mol%, more preferably 25 mol% to 40 mol%. By containing 20 mol% or more of PVA, the flexibility of the coating film is maintained. Therefore, the coating film is easily formed. In addition, by containing 50 mol% or less of PVA, the gas barrier layer 11 can have sufficient barrier properties.

[0036] The thickness of the coating film is, for example, 0.05 μm or more and 30 μm or less. When the gas barrier layer 11 includes a vapor-phase deposited film and a coating film, in the laminate 20, the vapor-phase deposited film is located on the resin film 10, and the coating film is located on the vapor-phase deposited film. As a result, the coating film is in contact with the vapor-phase deposited film.

[0037] From the viewpoint of strengthening the adhesion between the resin film 10 and the gas barrier layer 11, the surface of the resin film 10 on which the gas barrier layer 11 is to be formed may be subjected to a surface treatment such as a plasma treatment or a corona treatment. When the gas barrier layer 11 is formed from an inorganic oxide, an anchor coat layer may be located between the resin film 10 and the gas barrier layer 11. The surface treatment and the anchor coat layer improve the adhesion between the resin film 10 and the deposition layer after heat sterilization, and the barrier properties of the laminate 20.

[0038] The gas barrier layer 11 may include a layer formed of a metal foil and a metal nitride in addition to the above-mentioned vapor-deposited film and coating film, or instead of at least one of the above-mentioned vapor-deposited film and coating film. When the gas barrier layer 11 includes one or more layers other than the vapor-deposited film and coating film, another layer may be located between the vapor-deposited film and the coating film. Alternatively, another layer other than the coating film may be located between the vapor-deposited film and the resin film.

[0039] The laminate 20 may include a sealing layer, an adhesive layer, a decorative layer, and an information display layer in addition to the resin film 10 and the gas barrier layer 11. The sealing layer contains a thermoplastic resin. The sealing layer is melted by heat sealing when a package is formed using the laminate 20. As a result, in two laminates 20, an end of one laminate 20 is fused to an end of the other laminate 20. Alternatively, in one laminate 20, a first portion and a second portion of the laminate 20 are fused. The adhesive layer enhances adhesion between the gas barrier layer 11 and the upper layer of the gas barrier layer 11, or between the gas barrier layer 11 and the lower layer of the gas barrier layer 11. The decorative layer and the information display layer display decoration and information formed by printing.

[0040] The thickness of the laminate 20 may be selected according to various resistances required for a package formed using the laminate 20 and the processability required for the laminate 20. The thickness of the laminate 20 may be, for example, 30 μm or more and 300 μm or less.

[0041] The laminate 20 may be formed by the above-mentioned film forming method, various coating methods, a dry lamination method, an extrusion lamination method, or the like. [Packaging] The package will now be described with reference to FIG.

[0042] The packaging body 30 shown in FIG. 3 is formed from a laminate 20. The packaging body 30 defines a space capable of accommodating a packaged object inside the packaging body 30. In the example shown in FIG. 3, the packaging body 30 has a bag shape. The packaging body 30 is sealed by joining the ends over the entire circumference. In the packaging body 30, the gas barrier layer 11 is located on the inner side relative to the resin film 10. The shape and size of the packaging body 30 are not particularly limited. The shape and size of the packaging body 30 may be designed according to the shape and size of the packaged object. The packaged object may be, for example, food, medicine, cosmetics, etc.

[0043] The method of joining the ends of the laminate 20 is not particularly limited. For example, the ends of the laminate 20 may be joined using heat sealing as described above, or may be joined by other methods. In the example shown in Fig. 3, the packaging body 30 has a sealing portion 31 in which the ends of the first laminate and the second laminate are joined in two sheets of the laminate 20.

[0044] The packaging body 30 is not limited to the bag-like shape shown in Fig. 3. For example, the packaging body 30 may have a cylindrical shape or a bag-like shape with one cylindrical end sealed and the other cylindrical end open. Alternatively, the packaging body 30 may include the laminate 20 only in a portion thereof.

[0045] When the packaging body 30 using the laminate 20 is mass-produced, a roll-to-roll apparatus is used, and the laminate 20 is subjected to a process for forming the packaging body 30 while being transported by the roll-to-roll apparatus. The laminate 20 is transported by the roll-to-roll apparatus along the flow direction of the resin film 10. At this time, the laminate 20 is transported by the roll-to-roll apparatus in a state where it is pulled along the flow direction of the resin film 10. The resin film 10 is pulled along the flow direction with a stress that does not cause slack or bending in the laminate 20, in order to enable the transport of the laminate 20 and to prevent wrinkles from occurring in the packaging body 30 formed using the laminate 20.

[0046] [Physical properties of resin film] The resin film 10 will be described in more detail with reference to FIGS. FIG. 4 and FIG. 5 are 1 The spectrum of the resin film 10 measured by H-NMR is shown. When the standard substance is 1,4-bis-trimethylsilylbenzene-d4 and the chemical shift value of the standard substance signal is 0 ppm, three signals (peaks) originating from an isophthalic acid component having an isophthalic acid skeleton appear at 7.11 ppm to 7.25 ppm, a signal originating from a terephthalic acid component having a terephthalic acid skeleton appears at 7.40 ppm to 8.15 ppm, and a signal originating from a naphthalenedicarboxylic acid component having a naphthalenedicarboxylic acid skeleton appears at 8.34 ppm to 8.36 ppm. In addition, a signal of ethylene glycol (EG) appears at 4.1 ppm to 4.8 ppm, and signals of diethylene glycol (DEG) appear at 3.75 ppm to 3.90 ppm and 4.25 ppm to 4.35 ppm. FIG. 5 is an enlarged view of the NMR spectrum. The signal appearing at 7.11 ppm to 7.25 ppm is a signal derived from the hydrogen at position “A” indicated by the arrow among the hydrogens bonded to the aromatic ring of the isophthalic acid skeleton shown in the following general formula (1). [ka] The signals appearing at 7.40 ppm to 8.15 ppm are signals derived from four hydrogen atoms bonded to an aromatic ring of a terephthalic acid skeleton represented by the following general formula (2). [ka] The signals appearing at 8.34 ppm to 8.36 ppm are two signals derived from the hydrogen at the position "C" indicated by the arrow among the hydrogens bonded to the aromatic ring of the aromatic ring of the naphthalenedicarboxylic acid skeleton shown in the following general formula (3). [ka]

[0047] The signal integral value is the value obtained by integrating the relative intensity of the proton signal at each chemical shift when the chemical shift is changed by 0.01.

[0048] When the molar ratio of the isophthalic acid component was calculated from this spectrum, the molar ratio of the isophthalic acid component was 2×10 -1 mol% or more 9×10 -1 It is less than mol%.

[0049] The molar ratio of the isophthalic acid component can be calculated as follows: The sum of the integral values ​​of the signals corresponding to the terephthalic acid component, the isophthalic acid component, the naphthalenedicarboxylic acid component, the ethylene glycol component, and the diethylene glycol component in the spectrum (I sm ) is calculated and this is set as "100 mol%". In addition, the total integral value of the signal I sm The integral value of the signal of isophthalic acid component at 7.11 ppm to 7.25 ppm (I A ) ratio [(I A / I sm ) × 100] is the molar ratio of the isophthalic acid component.

[0050] The molar ratio of the naphthalene dicarboxylic acid component contained in the resin film 10 is 1×10 -2 mol% or more 6×10 -2 It is less than mol%.

[0051] The molar ratio of the naphthalenedicarboxylic acid component can be calculated in the same manner as the molar ratio of the isophthalic acid component. That is, the sum of the integral values ​​of the signals corresponding to the terephthalic acid component, the isophthalic acid component, the naphthalenedicarboxylic acid component, the ethylene glycol component, and the diethylene glycol component (I sm ) is set as "100 mol%". The sum of the signal integrals I sm The integrals of the signals of naphthalenedicarboxylic acid components at 8.34 ppm to 8.36 ppm (I B ) ratio [(IB / I sm ) × 100] is the molar ratio of the naphthalenedicarboxylic acid component.

[0052] When the molar ratio of the isophthalic acid component satisfies the above range, the resin film 10 has flexibility suitable for use in the package 30. As a result, even if an external force such as friction, piercing, bending, or impact is applied to the package 30, the resin film 10 absorbs the load by deforming in response to the external force, and cracks are less likely to form in the gas barrier layer 11 in contact with the resin film 10. -1 If the molar ratio of the isophthalic acid component is less than 9×10, the resin film 10 cannot obtain sufficient flexibility, and bending resistance is reduced. If the flexibility of the resin film 10 is low, cracks are likely to occur in the gas barrier layer 11, and the number of cracks increases, and the width and length of the cracks increase. As a result, it becomes difficult to maintain the quality of the contents of the package 30 in a good condition. On the other hand, if the molar ratio of the isophthalic acid component is less than 9×10, the resin film 10 cannot obtain sufficient flexibility, and bending resistance is reduced. If the flexibility of the resin film 10 is low, cracks are likely to occur in the gas barrier layer 11, and the number of cracks increases, and the width and length of the cracks increase. As a result, it becomes difficult to maintain the quality of the contents of the package 30 in a good condition. -1 If it exceeds mol %, the heat resistance of the resin film 10 decreases, for example, the melting point and softening temperature decrease, and a uniform and dense vapor-phase deposition film of aluminum oxide or silicon oxide cannot be formed on the resin film 10. Therefore, it becomes difficult to obtain a laminate 20 with high gas barrier properties. In order to adjust the content of the isophthalic acid component in the resin film 10 to satisfy the above range, for example, the ratio of recycled PET to the total PET may be adjusted during the production of the resin film 10, or an isophthalic acid component may be added during polymerization of PET. Since PET bottles sometimes contain isophthalic acid components to improve processability, recycled PET tends to contain more isophthalic acid components than virgin PET. For this reason, when increasing the content of the isophthalic acid component in the resin film 10, it is considered to increase the ratio of recycled PET.

[0053] When the molar ratio of the naphthalenedicarboxylic acid component satisfies the above range, the plane orientation coefficient at the surface of the resin film 10 becomes high. The plane orientation coefficient is a measure of the orientation and crystallinity of the film, and can be expressed by the following formula (1). The refractive index in the direction in which the refractive index is maximum is n1, the refractive index in the direction perpendicular to the direction in which the refractive index is maximum is n2, and the refractive index in the thickness direction of the film is n3.

[0054] Plane orientation coefficient Fn = (n1 + n2) / 2 - n3 ... (1) By increasing the plane orientation coefficient of the resin film 10, the resin film 10 can maintain high gas barrier properties and improve adhesion to the gas barrier layer 11. -2 If it is less than mol%, the gas barrier properties of the resin film 10 will be reduced, and cracks will be more likely to form in the gas barrier layer 11 when the resin film 10 is used as the package 30 and a load such as bending is applied. If the adhesion between the resin film 10 and the gas barrier layer 11 is reduced, the number of cracks generated in the gas barrier layer 11 will increase, and the width and length of the cracks will become large. If the number of cracks increases or the width and length of the cracks increase, the quality of the contents of the package 30 cannot be maintained at a good level. If the molar ratio of the naphthalenedicarboxylic acid component is 6×10 -2 If it exceeds mol %, the adhesion to the gas barrier layer 11 may decrease to such an extent that the gas barrier layer 11 may peel off from the resin film 10. In order to adjust the content of the naphthalene dicarboxylic acid component in the resin film 10 to satisfy the above range, for example, the ratio of recycled PET to the total PET may be adjusted during the production of the resin film 10, or the naphthalene dicarboxylic acid component may be added during polymerization of PET. Recycled PET tends to contain more naphthalene dicarboxylic acid components than virgin PET. For this reason, when increasing the content of the naphthalene dicarboxylic acid component in the resin film 10, it is possible to increase the ratio of recycled PET. Then, when producing the packaging body 30, the content ratio of the isophthalic acid component and the content ratio of the naphthalene dicarboxylic acid component in the resin film 10 are measured in advance, and a resin film whose content ratios satisfy conditions 1 and 2, respectively, can be selected. By producing the packaging body 30 using the resin film 10 having an isophthalic acid component content and a naphthalenedicarboxylic acid component content within the above-mentioned ranges, it is possible to increase the bending resistance of the packaging body 30 while maintaining good adhesion between the resin film 10 and the gas barrier layer 11. In addition, the molar ratio of the isophthalic acid component to the total amount of the dicarboxylic acid component and the diol component is 5×10 -1 mol% or more 9×10 -1 The molar ratio of the naphthalenedicarboxylic acid component is 4×10 or less. -2 mol% or more 6×10 -2 By providing the following, it is possible to more comprehensively improve the airtightness of a laminate for packaging in which a gas barrier layer is laminated.

[0055] As described above, according to one embodiment of the resin film for packaging, the laminate for packaging, and the packaging body, the following effects can be obtained. (1) The molar ratio of the isophthalic acid component contained in the resin film 10 is 2×10 -1 mol% or more 9×10 -1% or less, the flexibility of the resin film is enhanced. By increasing the flexibility of the resin film, the resin film becomes more easily deformed in response to an external force, and the bending resistance of the laminate 20 for packaging and the packaging body 30 is improved. In addition, when the molar ratio of the naphthalene dicarboxylic acid component is 1×10 -2 mol% or more 6×10 -2 Since the content is equal to or less than mol %, it is possible to increase the plane orientation coefficient of the resin film while suppressing peeling of the gas barrier layer 11. By increasing the plane orientation coefficient, the gas barrier property of the resin film 10 itself is improved. Therefore, it is possible to comprehensively improve the airtightness of the resin film 10 on which the gas barrier layer 11 is laminated.

[0056] (2) When the gas barrier layer 11 contains at least one of aluminum oxide and silicon oxide, a coating having transparency can be formed on the resin film 10. In addition, by reducing the water vapor permeability and oxygen permeability of the gas barrier layer 11, the gas barrier properties of the laminate can be improved.

[0057] (3) The gas barrier layer 11 is made of Si(OR 1 )4, or R 2 Si(OR 3 By including one or more silicon compounds represented by Formula 3 or hydrolysates of silicon compounds and a water-soluble polymer having a hydroxyl group, the water vapor permeability and oxygen permeability of the gas barrier layer 11 are reduced, and the gas barrier property of the laminate 20 can be further improved.

[0058] [Example] Laminates provided with a resin film will be described below in accordance with Examples 1 to 4 and Comparative Example 1. Note that the present invention is not limited to these Examples.

[0059] [Example 1] Three resin layers were laminated by co-extrusion to form a resin film of Example 1 having a thickness of 12 μm. The PET constituting the resin layer was a mixture of recycled PET regenerated by mechanical recycling and virgin PET. The mass ratio of the recycled PET was 80% by weight of the resin film, and the mass ratio of the virgin PET was 20% by weight of the resin film. A part of this resin layer was cut, and the cut resin piece was dissolved in trifluoroacetic acid, which is a solvent, to prepare a sample for NMR measurement.

[0060] This sample, 1 The NMR spectrum was obtained by measuring with a H-NMR (AVANCE NEO400, Bruker Japan). The measurement conditions were: number of scans: 256, flip angle: 30°, acquisition time: 4.19 sec, and waiting time: 2.00 sec. 1 Using the H-NMR spectrum, the sum of the integrals of the signals of the terephthalic acid component, isophthalic acid component, naphthalenedicarboxylic acid component, ethylene glycol component, and diethylene glycol component, I sm The integral value (I A ) and the integral value I of the signal of the naphthalenedicarboxylic acid component at 8.34 ppm to 8.36 ppm B And the total I sm , the integral value I of the isophthalic acid component signal A , the integral value I of the signal of the naphthalenedicarboxylic acid component B Using the above, the molar ratio of the isophthalic acid component [(I A / I sm )×100%] and the molar ratio of the naphthalenedicarboxylic acid component [(I B / I sm ) × 100% was calculated.

[0061] The molar ratio of the isophthalic acid component is 9 × 10 -1 mol%, and the molar ratio of the naphthalenedicarboxylic acid component is 4 × 10 -2 It was mol%. A thin film of metallic aluminum was evaporated onto this resin film using a vacuum deposition apparatus that uses electron beam heating while introducing oxygen gas, forming a 15 nm-thick evaporated thin film made of aluminum oxide.

[0062] Further, 72.1 g of hydrochloric acid (0.1N) was added to 17.9 g of tetraethoxysilane and 10 g of methanol, and the mixture was stirred for 30 minutes to hydrolyze the mixture, which was used as the first liquid. In addition, an aqueous solution of 5% by mass of polyvinyl alcohol and water / methanol=95 / 5 (mass ratio) was used as the second liquid. Then, the first liquid and the second liquid were mixed in a ratio of 70:30 by weight of solid contents, and the solution was applied to the resin film on which the vapor-phase deposition film was formed by gravure coating, and dried to obtain a laminate.

[0063] [Example 2] The molar ratio of isophthalic acid contained in the resin film is 9×10 -1 mol%, and the molar ratio of the naphthalenedicarboxylic acid component is 6 × 10 -2 Other than that, a resin film and a laminate including a resin film were produced in the same manner as in Example 1.

[0064] [Example 3] The molar ratio of isophthalic acid contained in the resin film is 7×10 -1 mol%, and the molar ratio of the naphthalenedicarboxylic acid component is 6 × 10 -2 Other than that, a resin film and a laminate including a resin film were produced in the same manner as in Example 1.

[0065] [Example 4] The molar ratio of isophthalic acid contained in the resin film is 5×10 -1 mol%, and the molar ratio of the naphthalenedicarboxylic acid component is 4 × 10 -2 Other than that, a resin film and a laminate including a resin film were produced in the same manner as in Example 1.

[0066] [Comparative Example 1] A resin film was formed in the same manner as in Example 1, except that a PET (PET P60, manufactured by Toray Industries, Inc.) not containing an isophthalic acid component or a naphthalenedicarboxylic acid component was used. In other words, signals at 7.11 ppm to 7.25 ppm and signals at 8.34 to 8.36 ppm were not detected. A resin film and a laminate including the resin film were produced in the same manner as in Example 1, except that a resin film and a laminate including the resin film were produced.

[0067] [Evaluation method] [Face orientation coefficient] The plane orientation coefficient ΔP was measured by a phase difference measurement method using a phase difference measurement device (KOBRA-WR, manufactured by Oji Scientific Instruments Co., Ltd.). Specifically, a 40 mm × 40 mm area was set at the center in the TD direction of the resin film and at the end in the TD direction. The phase difference was measured at an incident angle of 0° to 50° (10° pitch) for this area.

[0068] [Gas barrier properties] Two test pieces were prepared from each of the laminates of Examples 1 to 4 and the laminate of Comparative Example 1, and the gas barrier properties were evaluated after the Gelbo flex test.

[0069] (Gelboflex test) A Gelbo Flex test was performed on each test piece using a flexibility evaluation device (Gelbo Flex Tester, manufactured by Tester Sangyo Co., Ltd.). At this time, each test piece was attached to the fixed head of the flexibility evaluation device so as to assume a cylindrical shape. In detail, both ends of each test piece were held by the fixed head, and the initial gripping distance was set to 175 mm. Then, the stroke was set to 87.5 mm, the twist was set to 440°, and each test piece was twisted and released from the twist reciprocating motion 100 times at a speed of 40 times / min.

[0070] (Oxygen permeability) The oxygen permeability of the laminates of Examples 1 to 4 and Comparative Example 1 was measured using an oxygen permeability measuring device (product name: OX-TRAN-2 / 20, manufactured by MOCON). The measurement conditions were a temperature of 30°C and a relative humidity of 70% RH. The method used was in accordance with JIS K 7126-2:2006 and ASTM D3985-81. The unit of the measured oxygen permeability is [cc / m 2 ·day·atm.

[0071] (Water vapor permeability) The laminates of Examples 1 to 4 and Comparative Example 1 were measured for water vapor permeability (g / (m) using a water vapor permeability measuring device (product name: PERMATRAN-W-3 / 31, manufactured by MOCON). 2 The measurement conditions were a temperature of 40°C and a relative humidity of 90%. The measurement method used was in accordance with JIS K 7129-2:2019 and ASTM F1249-90.

[0072] [Evaluation Results] The planar orientation coefficient, oxygen permeability and water vapor permeability of the laminates of Examples 1 to 4 and the laminate of Comparative Example 1 were as shown in Table 1 below.

[0073] [Table 1] As shown in Table 1, the plane orientation coefficients of Examples 1 to 4 were larger in both the center row and the edge row of the resin film than that of Comparative Example 1. The oxygen permeabilities of the resin films of Examples 1 to 4 after the Gelbo Flex test were smaller than the oxygen permeability of the resin layer of Comparative Example 1. Similarly, the water vapor permeability of the resin films of Examples 1 to 4 after the Gelbo Flex test was smaller than the water vapor permeability of the resin layer of Comparative Example 1. That is, it was suggested that the resin films of Examples 1 to 4 maintained high airtightness even after application of external force, compared to the resin film of Comparative Example 1. [Explanation of symbols]

[0074] 10...Resin film 11...Gas barrier layer 20...Laminate 30...packaging

Claims

1. A resin film for packaging used to form a gas barrier layer, Contains polyethylene terephthalate, The polyethylene terephthalate includes recycled PET, which is at least one of PET regenerated by mechanical recycling and PET regenerated by chemical recycling; The polyethylene terephthalate contains a terephthalic acid component, an isophthalic acid component, and a naphthalenedicarboxylic acid component as dicarboxylic acid components of a polyester, When the total amount of the terephthalic acid component, the isophthalic acid component, the naphthalenedicarboxylic acid component, the ethylene glycol component and the diethylene glycol component contained as the diol component is taken as 100 mol %, The molar ratio of the isophthalic acid component to the total amount is 2×10 －１ mol% or more 9×10 －１ mol % or less, and the molar ratio of the naphthalenedicarboxylic acid component is 1×10 －２ mol% or more 6×10 －２ mol% or less Resin film for packaging.

2. The molar ratio of the isophthalic acid component to the total amount is 5×10 －１ mol% or more 9×10 －１ mol % or less, and the molar ratio of the naphthalenedicarboxylic acid component is 4×10 －２ mol% or more 6×10 －２ 2. The resin film for packaging according to claim 1, wherein the content of the polyvinyl chloride in the resin film is 1 mol % or less.

3. The resin film for packaging according to claim 1 , wherein a surface on which the gas barrier layer is to be formed has been subjected to a plasma treatment or a corona treatment.

4. The resin film for packaging according to any one of claims 1 to 3, wherein the formation of the gas barrier layer comprises forming an inorganic oxide film or a metal film by any one of a vacuum deposition method, a sputtering method, an ion plating method, and a plasma vapor phase deposition method.

5. A resin film for packaging described in any one of claims 1 to 4, which is used to form a decorative layer or an information display layer formed by printing in addition to the gas barrier layer.

6. A resin film for packaging described in any one of claims 1 to 5, which is used to form a sealing layer containing a thermoplastic resin in addition to the gas barrier layer.

7. A laminate for packaging, comprising a resin film for packaging according to any one of claims 1 to 6, and a gas barrier layer having at least one of an inorganic oxide film and a metal film.

8. A laminate for packaging, comprising a resin film for packaging described in any one of claims 1 to 6 and a sealing layer containing a thermoplastic resin.

9. A pair of laminates for packaging, the laminates having the resin film for packaging according to any one of claims 1 to 6, a gas barrier layer, and a sealing layer containing a thermoplastic resin, A package in which the sealing layer of one of the laminates for packaging and the sealing layer of the other laminate for packaging are fused together.

10. A laminate for a package comprising the resin film for a package according to any one of claims 1 to 6, a gas barrier layer, and a sealing layer containing a thermoplastic resin, A package in which the first and second parts of the package laminate are fused together.

Images