Packaging material

Abstract

To provide a packaging material excellent in moldability, colorability, and strength.SOLUTION: The present invention is directed to a packaging material 1 which includes a metal foil layer 52 laminated inside a substrate layer 51 made of a heat-resistant resin, and a sealant layer 53 made of a thermoplastic resin laminated inside the metal foil layer 52 and which is provided with a colored adhesive layer 61 between the metal foil layer 52 and the substrate layer 51. The colored adhesive layer 61 is constituted of a colored adhesive cured film containing a coloring pigment and an adhesive. The colored adhesive cured film has a Young's modulus of 450-700 MPa in a tensile test according to JIS K7161-1:2014.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to packaging materials used as exterior materials for batteries (electricity storage devices) such as those for notebook computers, mobile phones, and in-vehicle (mobile) or stationary secondary batteries (lithium ion secondary batteries), as well as packaging materials for food and pharmaceuticals, packaging containers, electricity storage devices, and methods for producing colored adhesive compositions. [Background technology]

[0002] There is an increasing demand for batteries such as lithium-ion secondary batteries to be colored to match the appearance and color of the electrical equipment to which they are attached. In particular, devices are often colored black to give them a sense of dignity and luxury, and in such cases, batteries are often also colored black.

[0003] The packaging material for this type of device generally uses a laminate in which a resin base layer is laminated on the outer surface of a metal foil layer and a resin sealant layer is laminated on the inner surface. To color the battery black or other colors, various methods are available, such as coloring the resin layer used in the packaging material, providing a printed layer under the base layer, coloring the adhesive layer between the base layer and the metal layer, or coloring the adhesive layer between layers if the base layer is made up of multiple layers.

[0004] For example, Patent Document 1 discloses an example in which a pigment is added to the adhesive layer between the base layer and metal foil layer of a battery packaging material to create an identification mark, and describes that the pigment can be identified when the pigment addition amount is in the range of 10% by mass to 30% by mass, and that the moldability is also good.

[0005] Furthermore, Patent Document 2 discloses an example in which the base layer is made into a multi-layer (two-layer) structure, and a pigment is added to the adhesive layer between the two base resin layers to create an identification mark, and describes that the mark can be identified when the pigment addition amount is in the range of 5% to 30% by mass, and also has good moldability.

[0006] However, when adding a pigment such as carbon black to the adhesive layer between the base layer and the metal foil layer, increasing the amount of carbon black added to the adhesive layer to make it black can reduce the adhesive strength, causing interlayer delamination between the base layer and the adhesive layer during molding, which can make it impossible to mold the product into the desired shape.

[0007] Furthermore, such delamination (partial delamination) between the base material layer and the adhesive layer occurs not only during molding, but also when the black packaging material is sealed after the electrodes and electrolyte are sealed in, or when a battery packaged in the black packaging material is used in a somewhat harsh environment such as high temperature and humidity.

[0008] The problem of delamination is not limited to black packaging materials using carbon black, but may also occur in packaging materials colored with other pigments.

[0009] Under these circumstances, Patent Document 3 discloses a technology in which the amount of color pigment such as carbon black added is specified within a predetermined range, thereby suppressing a decrease in adhesive strength due to the addition of the pigment to the adhesive layer and achieving good moldability. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-054563 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-072911 [Patent Document 3] Patent Publication No. 2021-109706 Summary of the Invention [Problem to be solved by the invention]

[0011] As mentioned above, when adding a pigment such as carbon black to the adhesive layer to color the packaging material, it is important to specify the amount of pigment added within a predetermined range.

[0012] However, simply setting the amount of pigment added to the adhesive layer within a specific range can result in uneven dispersion of the pigment in the adhesive layer, causing the pigment particles to aggregate unevenly, resulting in defects in the adhesive layer, reduced adhesive strength, and a decrease in the Young's modulus of the adhesive layer.As a result, when forming the adhesive into a container (case) shape by deep drawing or stretch molding, the external forces during the forming process cannot be efficiently dispersed, and the desired formability cannot be achieved.

[0013] The present invention has been made in view of the above-mentioned problems, and has an object to provide a packaging material that has excellent formability and colorability, and a packaging container that uses the packaging material, an exterior material for an electricity storage device, an electricity storage device, and a method for producing a colored adhesive composition. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention comprises the following means.

[0015] [1] A packaging material comprising a metal foil layer laminated on the inside of a base layer made of a heat-resistant resin, and a sealant layer made of a thermoplastic resin laminated on the inside of the metal foil layer, and a colored adhesive layer provided between the metal foil layer and the base layer, the colored adhesive layer is composed of a colored adhesive cured film containing a color pigment and an adhesive, The packaging material is characterized in that the colored adhesive cured film has a Young's modulus of 450 MPa to 700 MPa according to the tensile test of JIS K7161-1:2014.

[0016] [2] The packaging material according to the preceding paragraph 1, wherein the cured colored adhesive film has a breaking elongation of 21% to 60% in a tensile test according to JIS K7161-1:2014.

[0017] [3] The colored adhesive layer contains the color pigment in an amount of 2% by mass or more and less than 5% by mass, The colored adhesive layer has a density of 5 g / m 2 ~10g / m 2 3. The packaging material according to item 1 or 2, wherein the colored adhesive cured film is a colored adhesive cured film.

[0018] [4] The adhesive of the colored adhesive layer contains a two-component curing polyester urethane resin derived from a polyester resin as a base resin and a polyfunctional isocyanate compound as a curing agent, The polyester resin as the base resin has a number average molecular weight (Mn) of 8,000 to 25,000 and a weight average molecular weight (Mw) of 15,000 to 50,000, and the ratio thereof (Mw / Mn) is 1.3 to 2.5, 4. The packaging material according to claim 1, wherein the polyfunctional isocyanate compound as a curing agent contains 50 mol % or more of an aromatic isocyanate.

[0019] [5] In the two-component curing polyester urethane resin, the polyester resin as a main component is made from dicarboxylic acid and dialcohol as raw materials, 5. The packaging material according to item 4, wherein the dicarboxylic acid includes an aliphatic dicarboxylic acid having an even number of methylene chains and an aromatic dicarboxylic acid, and the content of the aromatic dicarboxylic acid relative to the total amount of these is 40 mol % to 80 mol %.

[0020] [6] The packaging material according to any one of claims 1 to 5, wherein the metal foil layer has a chemical conversion coating on at least one surface thereof.

[0021] [7] The packaging material according to any one of claims 1 to 6, wherein a matte coating layer is provided on the outer surface of the base material layer.

[0022] [8] A packaging container, characterized in that the packaging material according to any one of claims 1 to 7 has a molded portion formed by deep drawing or stretch molding.

[0023] [9] An exterior packaging material for an electricity storage device, characterized in that it is made up of the packaging material according to any one of items 1 to 7 above and / or the packaging container according to item 8 above.

[0024]

[10] A power storage device body; and the exterior material according to claim 9, The power storage device, wherein the power storage device main body is sheathed with the sheath material.

[0025]

[11] A method for producing a colored adhesive composition that constitutes a cured colored adhesive film in the packaging material according to any one of items 1 to 7, comprising: The color pigment is mixed with a vehicle to prepare a liquid colorant; The adhesive is made by mixing the liquid coloring agent with the main agent of the main agent and the curing agent, and then preparing a pigmented adhesive main agent. A method for producing a colored adhesive composition, characterized in that the pigmented adhesive base agent and the curing agent are blended to produce the colored adhesive composition. [Effects of the Invention]

[0026] According to the packaging material of invention [1], the colored adhesive layer contains a pigment, which allows for good colorability. Furthermore, because the Young's modulus of the colored adhesive layer containing the colored pigment is specified within a predetermined range, it is possible to efficiently disperse the effects of external pressure, resulting in sufficient strength and excellent formability. This makes it possible to mold deep, sharp shapes, for example, and prevents problems such as partial cracking and peeling of the colored adhesive layer during molding and sealing, or when used in harsh environments such as high temperatures and humidity.

[0027] According to the packaging material of the invention [2], since the breaking elongation is specified within a predetermined range, good formability can be obtained when performing deep drawing and stretch forming. Furthermore, the base layer does not peel off, and the adhesiveness of the base layer can be further improved, thereby suppressing the occurrence of delamination.

[0028] According to the packaging material of invention [3], the colored adhesive layer is a cured colored adhesive film of a predetermined amount, and the concentration (content) of the colored pigment in the colored adhesive layer is specified within a predetermined range, thereby achieving uniform coloring throughout. Furthermore, the brittleness of the colored adhesive layer due to the inclusion of the colored pigment is prevented, the fracture path (distance) of the cured colored adhesive film is lengthened, fracture elongation is improved, and sufficient adhesion between the substrate layer and the metal foil layer is maintained, resulting in better formability during deep drawing and stretch forming. Furthermore, even when left in a high-temperature, high-humidity environment after forming, the substrate layer does not peel off, causing damage to the appearance. As a result, the substrate layer does not peel off even in evaluation tests that are affected by the inclusion of a colored pigment, especially in a hot water immersion test, which is the most severe environmental test, and the adhesion of the substrate layer is further improved.

[0029] According to the packaging material of invention [4], the colored adhesive layer contains a specific two-component curing polyester urethane resin, which provides adequate strength, elongation, and excellent heat resistance. The polyester resin, which is the main component of the colored adhesive layer, is adjusted to a specific molecular weight distribution, making it suitable for adhesive application. Furthermore, the polyamide film used as the base layer is adjusted to a specific molecular weight distribution, making the film difficult to tear and providing good puncture resistance.

[0030] According to the packaging material of invention [5], the two-component curing polyester urethane resin contained in the colored adhesive layer has a specific composition of the polyester resin as the main component, which provides even better adhesion and more reliably prevents peeling between the base layer and the metal foil layer.

[0031] Invention [6] A chemical conversion coating is provided on the surface of the metal foil layer, which prevents corrosion of the metal foil layer and improves the corrosion resistance of the entire packaging material.

[0032] According to the packaging material of invention [7], a matte coating layer is provided on the surface of the base material layer, which further improves formability and durability. In addition, the presence of the matte coating layer improves the appearance quality of the packaging material, prevents problems such as adhesion between packaging materials, and makes it easier to handle the packaged product.

[0033] According to the packaging container of the invention [8], since it uses the packaging material of the above invention, it can obtain the same effects as those described above.

[0034] According to the packaging material for an electricity storage device of the invention [9], the packaging material and packaging container of the above invention are used, and therefore the same effects as those described above can be obtained.

[0035] According to the electricity storage device of the invention

[10] , since the exterior material of the above invention is used, the same effects as those described above can be obtained.

[0036] According to the manufacturing method of the invention

[11] , a colored adhesive composition in which the color pigment is uniformly dispersed can be manufactured, and therefore, a colored adhesive cured film having the above-mentioned unique physical properties can be reliably formed. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a side cross-sectional view showing an electricity storage device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the electricity storage device according to the embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an exterior packaging material for an electricity storage device according to an embodiment. [Figure 4] FIG. 4 is a schematic diagram for explaining MD and TD in a resin film. [Figure 5] FIG. 5 is a graph showing the SS curve of a cured film of a two-component curing polyester urethane resin adhesive. [Figure 6] FIG. 6 is a perspective view showing a molded product of a packaging material sample used in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] FIG. 1 is a side cross-sectional view showing an electricity storage device according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing the electricity storage device according to the embodiment.

[0039] As shown in both figures, the electricity storage device of this embodiment includes a casing 11 and an electricity storage device main body 10 such as an electrochemical element housed inside the casing 11.

[0040] The casing 11 is composed of a tray member (packaging container) 2 formed by an exterior material 1 and having a rectangular shape in a plan view, and a cover member 3 formed by an exterior material (packaging material) 1 and having a rectangular shape in a plan view.

[0041] The tray member 2 is formed from a molded product obtained by using a method such as deep drawing to mold the exterior material 1. The tray member 2 has a downward recess formed in the entire middle region except for the outer peripheral edge, forming a recessed portion 21 that is rectangular in plan view, and an outwardly protruding flange portion 22 is integrally formed on the outer periphery of the opening edge of the recessed portion 21.

[0042] The cover member 3 is made of a sheet-shaped exterior material 1. The outer peripheral edge of the cover member 3 is configured as a flange portion 32 that corresponds to the flange portion 22 of the tray member 2.

[0043] The tray member 2 and the exterior material 1 as the cover member 3 are made of an outer envelope laminate which is a laminate sheet or film having flexibility and resilience.

[0044] The electricity storage device main body 10 is not particularly limited, but examples thereof include a battery main body, a capacitor main body, a condenser main body, etc. The electricity storage device main body 10 is formed in a shape corresponding to the recessed portion 21 of the tray member 2.

[0045] Then, with the energy storage device main body 10 housed within the recessed portion 21, the cover member 3 is placed on the tray member 2 so as to cover the recessed portion 21, and the flange portions 22, 32 of the tray member 2 and the cover member 3 are heat-fused together to form the energy storage device of this embodiment.

[0046] Although not shown in the figure, one end (inner end) of the tab lead is connected to the energy storage device main body 10, and the other end (outer end) is arranged in a state where it is pulled out to the outside of the energy storage device, so that electricity can be input and output to and from the energy storage device main body 10 via the tab lead.

[0047] 3 is a schematic cross-sectional view showing the basic structure of the outer laminate material constituting the packaging material 1 in this embodiment. As shown in the figure, the packaging material (laminate material) 1 used in this embodiment includes a base material layer (heat-resistant resin layer) 51, a metal foil layer (barrier layer) 52 bonded to one surface (inner surface) of the base material layer 51 via a first adhesive layer 61 serving as a colored adhesive layer or outer adhesive layer, and a sealant layer (heat-fusible resin layer) 53 bonded to one surface (inner surface) of the metal foil layer 52 via a second adhesive layer 62 serving as an inner adhesive layer. Chemical conversion coatings 63, 63 are formed on both surfaces of the metal foil layer 52, and a matte coating layer 50 is laminated on the outer surface of the base material layer 51.

[0048] In this embodiment, the base layer 51 is made of a polyamide film, a polyester film, or the like, and an oriented film thereof is used. Among these, in terms of formability and strength, it is preferable to use a biaxially oriented polyamide film, a biaxially oriented polybutylene terephthalate (PBT) film, a biaxially oriented polyethylene terephthalate (PET) film, or a biaxially oriented polyethylene naphthalate (PEN) film.

[0049] Examples of polyamide films include nylon 6 film, nylon 6,6 film, and MXD nylon film.

[0050] The base layer 51 may be formed of a single layer or multiple layers. When formed of multiple layers, a multi-layer structure made of a PET film / polyamide film can be exemplified.

[0051] It is desirable to apply an easy-adhesion treatment to the lower surface of the stretched film used as the base layer 51, i.e., the surface that is bonded to the first adhesive layer 61, to impart wettability in order to improve the adhesive strength with the adhesive 61.

[0052] Here, in order to meet the demand for higher capacity and improved safety of electricity storage devices (batteries), the base material layer 51 of the packaging material for electricity storage devices is desired to have even higher formability and puncture resistance. However, according to research by the present inventors, in order to improve the latter performance (puncture resistance), polyamide film is more suitable than polyester film, and more preferably, good formability and puncture resistance can be obtained by using a polyamide film that satisfies the following physical properties (1) to (5).

[0053] (1) The hot water shrinkage percentage of the base layer 51 in both the TD and MD is preferably adjusted to 2.0% to 5.0%, more preferably 2.5% to 4.5%.

[0054] As shown in FIG. 4, "MD" refers to the molding direction of the resin film F (the direction of resin flow), and "TD" refers to the direction perpendicular to MD. Furthermore, hot water shrinkage refers to the rate of dimensional change in the shrinkage direction (stretching direction) of a film (measurement object) before and after immersion in hot water at 100°C for 5 minutes. For example, if the dimension in the shrinkage direction (MD or TD) before immersion in hot water is "X" and the dimension in the shrinkage direction (MD or TD) after immersion in hot water is "Y," the hot water shrinkage (%) in the shrinkage direction (MD or TD) can be calculated using the relational expression {(XY) / X} × 100. In the present invention, the "hot water shrinkage" indicating the characteristic value of a polyamide film is preferably the average value of the hot water shrinkage (average hot water shrinkage). In the present invention, the average hot water shrinkage refers to the average value of the hot water shrinkage at three points, namely, two points at both ends and one point at the center, in one direction of the sheet (film) to be measured. However, in the present invention, depending on the size of the electricity storage device main body 10, it is also possible to use the hot water shrinkage rate measured at a specific location (hot water absorption rate at a reference position) rather than the average value as the "hot water shrinkage rate" indicating the characteristic value of the polyamide film.

[0055] (2) The difference between the hot water shrinkage rate in MD and the hot water shrinkage rate in TD of the base layer 51 is preferably adjusted to 1.5% or less, more preferably adjusted to 1.2% or less. Specifically, when the average hot water shrinkage rate in MD is "MDz" and the hot water shrinkage rate in TD is "TDz", the relationship |MDz-TDz|≦1.5% should be established, more preferably adjusted to 1.2% or less.

[0056] (3) The MD and TD moduli of elasticity of the base layer 51 are both preferably adjusted to 1.5 GPa to 3 GPa, and more preferably adjusted to 2.0 GPa to 2.5 GPa.

[0057] (4) At least one of the TD breaking strength and MD breaking strength of the base layer 51 is preferably adjusted to 320 MPa or more, and more preferably adjusted to 400 MPa or less.

[0058] (5) The number average molecular weight of nylon used as the polyamide film constituting the base layer 51 is preferably adjusted to 15,000 to 30,000, more preferably 20,000 to 25,000.

[0059] In this embodiment, when the hot water shrinkage rate in TD and MD is 2.0% or more, the substrate layer 51 has appropriate flexibility and can ensure good formability. In addition, when the hot water shrinkage rate is 5.0% or less, the substrate layer 51 can avoid excessive flexibility and maintain the desired strength.

[0060] Furthermore, in this embodiment, when the difference in hot water shrinkage rate between TD and MD is adjusted to be within the above-mentioned specific range, it becomes possible to efficiently disperse the force from external pressure, and the base material layer 51 can reliably maintain the desired strength.

[0061] Furthermore, when the elastic moduli in the TD and MD are adjusted to fall within the above-mentioned specific ranges, the base layer 51 can more reliably maintain appropriate flexibility and strength.

[0062] Furthermore, when the breaking strengths in the TD and MD are adjusted to fall within the above-mentioned specific ranges, the base layer 51 can more reliably obtain the desired strength.

[0063] By using a polyamide film having the above-described properties for the base material layer 51, an exterior packaging material 1 can be obtained that has good formability and sufficient puncture resistance.

[0064] Furthermore, when the number average molecular weight of the nylon used for the base layer 51 is 15,000 or more, the base layer 51 becomes less likely to break, and when the molecular weight is 30,000 or less, the flexibility of the base layer 51 can be maintained and the base layer 51 becomes less likely to crack.

[0065] In this embodiment, the relative viscosity of the polyamide film serving as the base material layer 51 is preferably adjusted to 2.9 to 3.1. In other words, when the relative viscosity is adjusted to the above-mentioned specific range, the strength and flexibility of the base material layer 51 can be more effectively imparted, and the packaging material 1 can be reliably obtained with good formability and high puncture resistance.

[0066] In this embodiment, the puncture strength of the exterior material 1 is preferably in the range of 22N to 30N, more preferably 24N to 30N, and even more preferably 26N to 30N.

[0067] In this embodiment, the thickness of the base layer 51 is preferably adjusted to 9 μm to 50 μm, and more preferably to 12 μm to 30 μm. In particular, when a polyester film is used as the base layer 51, the thickness is preferably adjusted to 9 μm to 50 μm, and when a polyamide film is used, the thickness is preferably adjusted to 10 μm to 50 μm. By setting the thickness to a value equal to or greater than the preferred lower limit, sufficient strength as a packaging material can be ensured, and by setting the thickness equal to or less than the preferred upper limit, stress during stretch forming or draw forming can be reduced, improving formability.

[0068] Here, the distribution of hot water shrinkage in the polyamide film of this embodiment will be described. First, in a square polyamide film, when the hot water shrinkage at three points on both sides and the centerline in the machine direction (MD) is defined as the three fixed-point hot water shrinkage in MD, and the hot water shrinkage at three points on both sides and the centerline in the transverse direction (TD) is defined as the three fixed-point hot water shrinkage in TD, it is preferable to use a film in which the difference between the maximum and minimum fixed-point hot water shrinkage of the six fixed-point hot water shrinkages, i.e., the three fixed-point hot water absorbencies in MD and the three fixed-point hot water absorbencies in TD, is adjusted to 2.5 or less.

[0069] The average value of the hot water shrinkage rates at the three fixed points in MD corresponds to the average hot water shrinkage rate in MD, and the average value of the hot water shrinkage rates at the three fixed points in TD corresponds to the average hot water shrinkage rate in TD.

[0070] Here, the three regions indicated by dashed lines in Figure 4 are all square regions of the same size in the polyamide film (base layer 51). If these square regions satisfy the above-mentioned hot water shrinkage distribution conditions, uneven flexibility is suppressed throughout the base layer 51. Therefore, even if external stress is applied, the stress is distributed throughout the base layer 51, making it less likely to tear, and reliably improving strength.

[0071] In this embodiment, the base layer 51 is formed of a polyamide film, but as described above, other layers may be laminated on the base layer 51.

[0072] Furthermore, it is preferable to use a resin for base layer 51 that has a melting point that is 10° C. or more higher than that of all the resins that make up sealant layer 53, and more preferably a resin that is 20° C. or more higher. In other words, when this configuration is used, adverse effects of heat on base layer 51 can be avoided when sealant layer 53 is heat-sealed.

[0073] The sealant layer (heat-sealable resin layer, thermoplastic resin layer) 53 provides excellent chemical resistance to highly corrosive electrolytes used in lithium-ion secondary batteries and the like, and also serves to impart heat-sealing properties to the exterior packaging material 1.

[0074] Although there are no particular limitations on the sealant layer 53, it is preferably a layer made of an unstretched film of a heat-sealable resin. In terms of chemical resistance and heat sealability, this unstretched film of a heat-sealable resin is preferably made of an unstretched film of at least one type of heat-sealable resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers.

[0075] The thickness of the sealant layer 53 is preferably set to 20 μm to 80 μm, and more preferably to 25 μm to 50 μm. That is, by setting the thickness to 20 μm or more, it is possible to sufficiently prevent the occurrence of pinholes, and by setting the thickness to 80 μm or less, it is possible to reduce the amount of resin used, thereby reducing costs.

[0076] The sealant layer 53 may be a single layer or multiple layers. In the case of multiple layers, a three-layer film in which random polypropylene films are laminated on both sides of a block polypropylene film can be exemplified.

[0077] In this embodiment, the metal foil layer 52 serves as a gas barrier that prevents the intrusion of oxygen and moisture.

[0078] The metal foil layer 52 is not particularly limited, but examples thereof include aluminum foil, copper foil, and stainless steel foil, with aluminum foil being commonly used. Among these, aluminum foil is particularly preferred. In particular, when an Al-Fe alloy foil containing 0.7% to 1.7% by mass of Fe is used, it has excellent strength and ductility, and good formability can be obtained.

[0079] The thickness of the metal foil layer 52 is preferably set to 20 μm to 100 μm, and more preferably to 25 μm to 60 μm. That is, a thickness of 20 μm or more can prevent pinholes from occurring during rolling when manufacturing the metal foil, and a thickness of 100 μm or less can reduce stress during stretch forming or drawing, improving formability.

[0080] A resin base layer 51 and a sealant layer 53 are laminated on the outer and inner surfaces of the metal foil layer 52, respectively. However, although only in minute amounts, light, oxygen, and liquids may penetrate these resin layers 51 and 53 from the outside (the base layer 51 side), and contents (battery electrolyte, food, medicine, etc.) may seep in from the inside (the sealant layer 53 side). If these intruders reach the metal foil layer 52, they may cause corrosion of the metal foil layer 52. Therefore, in the present invention, the corrosion resistance of the metal foil layer 52 can be improved by forming a highly corrosion-resistant chemical conversion coating 63 on the surface of the metal foil layer 52.

[0081] For example, in the case of chromate treatment, an aqueous solution of any one of the mixtures 1) to 3) below is applied to the surface of a metal foil that has been degreased, and then dried.

[0082] 1) A mixture of phosphoric acid, chromic acid, and at least one of a metal salt of fluoride and a non-metal salt of fluoride. 2) A mixture of phosphoric acid, an acrylic resin, a chitosan derivative resin, or a phenolic resin, and at least one of chromic acid and a chromium (III) salt. 3) A mixture of phosphoric acid, an acrylic resin, a chitosan derivative resin, or a phenolic resin, at least one of chromic acid and a chromium (III) salt, and at least one of a metal salt of fluoride and a non-metal salt of fluoride. The amount of chromium deposited on the chemical conversion coating 63 is 0.1 mg / m 2 ~50mg / m 2 It is recommended to set it at 2 mg / m 2 ~20mg / m 2 It is better to set it to .

[0083] The chemical conversion coating 63 may be applied to both sides of the metal foil layer 52 or to only one side.

[0084] In this embodiment, the first adhesive layer (colored adhesive layer) 61 is a layer that bonds the metal foil layer 52 and the base material layer 61 and also imparts color (including achromatic colors) to the outer surface of the exterior packaging material 1, and is composed of a cured film (colored adhesive cured film) of a colored adhesive composition that contains a colored pigment and a specific adhesive (adhesive component).

[0085] The color pigment is not particularly limited, but suitable examples include azo pigments, phthalocyanine pigments, condensed polycyclic pigments, inorganic pigments, etc. Examples of black pigments include carbon black, and examples of white pigments include TiO2 and SiO2.

[0086] It is preferable to use color pigments having an average particle size of 0.05 μm to 5 μm, and it is particularly preferable to use color pigments having an average particle size of 0.1 μm to 2.5 μm.

[0087] It is preferable to use a pigment disperser for dispersing the pigment, and a pigment dispersant such as a surfactant may also be used for dispersing the pigment.

[0088] However, when adding a pigment with a small average particle size to an adhesive, adding the pigment directly can result in the formation of secondary agglomerated particles, making it impossible to disperse the pigment evenly in the adhesive.

[0089] For this reason, for example, a liquid colorant composed of an ink (also referred to as a "high-concentration ink") in which a pigment is dissolved at a high concentration in a component other than the pigment, such as a vehicle described below, can be prepared, and this liquid colorant can be added to and mixed with the main adhesive agent, thereby making it possible to produce a colored adhesive composition in which the pigment is uniformly dispersed in the adhesive at a specified content, without secondary aggregation or precipitation of the pigment.

[0090] Liquid ink is made by mixing pigments and other colorants with a vehicle (a mixture of resin and solvent) that acts as a vehicle to create the ink base, to which auxiliary agents (surfactants, viscosity adjusters, antistatic agents, antioxidants, pigment dispersants, leveling agents, anti-settling agents, anti-foaming agents, etc.) are added, and the ink goes through a grinding and dispersion process using various mills to uniformly disperse the colorants.

[0091] The resin for the vehicle may be one or a combination of two or more of the following: a copolymer of vinyl chloride and vinyl acetate, chlorinated rubber, chlorinated polypropylene, acrylic resin, polyamide resin, polyurethane resin, and nitrocellulose. In the present invention, it is preferable to use the same polyester resin as the base agent for the adhesive as the resin for the vehicle, as this can improve compatibility (mixing) with the base agent for the adhesive.

[0092] As the solvent for the vehicle, one or a combination of two or more of toluene, methyl ethyl ketone, ethyl acetate, isopropyl alcohol, etc. In the present invention, as the solvent for the vehicle, it is preferable to use ethyl acetate, which is also used as a solvent for adhesives, and toluene or methyl ethyl ketone can also be used as a co-solvent if necessary.

[0093] As mentioned above, the pigment may be an azo pigment, a phthalocyanine pigment, a condensed polycyclic pigment, an inorganic pigment, or the like, and carbon black is particularly recommended as a black pigment.

[0094] The preferred blending ratios of the components that make up the ink are vehicle resin: 15% to 25% by mass, vehicle solvent: 40% to 70% by mass, colorant (pigment): 5% to 50% by mass, and auxiliary: 1% to 5% by mass.

[0095] In the present invention, carbon black (CB) is used as the colorant, and a black ink with a pigment concentration of 30% to 40% by mass (resin: solvent: CB: auxiliary agent = 15% to 25% by mass: 40% to 45% by mass: 30% to 40% by mass: 3% to 5% by mass) is prepared in advance as a liquid colorant.

[0096] In the ink manufacturing process, the important step is the preparation step, in which the vehicle (polyester resin, solvent), pigment (carbon black), and other auxiliaries are mixed. In the preparation step, it is preferable to use a solvent that will be an ink component so that the resin components can be easily kneaded.

[0097] In particular, when producing an ink containing a pigment, it is preferable to include a step (dispersion step) during or after the preparation step in which a mixture containing a resin, a solvent, a pigment, etc. is kneaded to finely disperse the pigment particles to a desired particle size.

[0098] In this dispersion step, various dispersing machines can be used, such as a paint shaker, ball mill, attritor, sand mill, bead mill, dyno mill, roll mill, ultrasonic mill, high-pressure collision dispersing machine, etc. In the dispersion step, one type of dispersing machine may be used to carry out dispersion treatment once or multiple times, or two or more types of dispersing machines may be used in combination to carry out dispersion treatment multiple times.

[0099] The above-mentioned dispersion process is important when manufacturing an ink containing a pigment. By adding an ink with a high concentration of uniformly dispersed pigment to the adhesive base so that the pigment content is a specified amount, it is possible to prevent the pigments from forming secondary agglomerated particles and to disperse the pigment uniformly in the adhesive base. Even if the pigment is left to stand for several months after addition, no settling of the pigment occurs, and an adhesive base with good pigment dispersibility is obtained.

[0100] By reacting this pigment-added adhesive base (polyester resin) with an isocyanate curing agent, a uniform colored adhesive composition can be obtained that is free of coating defects caused by secondary pigment agglomeration particles, and a colored adhesive cured film can be obtained that has a predetermined good Young's modulus and good shielding properties, adhesion, water resistance, and chemical resistance.

[0101] The adhesive component of the first adhesive layer 61 is composed of an adhesive containing a two-component curing polyester urethane resin, which is made of a polyester resin as a main component and a polyfunctional isocyanate compound as a curing agent. In the present invention, by specifying the molecular weight of the polyester resin, which is the main component of the two-component curing polyester urethane resin, and by specifying the type of polyfunctional isocyanate compound, which is the curing agent, it is possible to increase adhesive strength and formability and suppress delamination when deep molding is performed during molding of the exterior packaging material 1.

[0102] The polyester resin used as the base resin is a copolymer made from dicarboxylic acid and dialcohol as raw materials, and the preferred materials and compositions are as follows:

[0103] It is preferable to use both aliphatic dicarboxylic acids and aromatic dicarboxylic acids as the dicarboxylic acids. Furthermore, whether the number of methylene chains in the aliphatic dicarboxylic acid is odd or even is a factor that affects the crystallinity of the resin. Since dicarboxylic acids with an even number of methylene chains produce hard resins with high crystallinity, it is preferable to use aliphatic dicarboxylic acids with an even number of methylene chains. Examples of aliphatic dicarboxylic acids with an even number of methylene chains include succinic acid (2 methylene chains), adipic acid (4 methylene chains), suberic acid (6 methylene chains), and sebacic acid (8 methylene chains).

[0104] Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, and phthalic anhydride.

[0105] Furthermore, by setting the content of aromatic dicarboxylic acid to the total amount of aliphatic dicarboxylic acid and aromatic dicarboxylic acid in the range of 40 mol% to 80 mol%, in other words, by keeping the content of aliphatic dicarboxylic acid in the range of 20 mol% to 60 mol%, a resin with high adhesive strength and good formability can be produced, and the molded product can be molded into a case with a high side wall, and interlayer delamination between the metal foil layer 52 and the base material layer 51 can be suppressed.

[0106] Here, if the content of aromatic dicarboxylic acid is less than 40 mol %, the film properties will be reduced and cohesive peeling will be more likely to occur, which may result in delamination.

[0107] On the other hand, if the content of aromatic dicarboxylic acid exceeds 80 mol %, the resin becomes hard and adhesion tends to decrease.A particularly preferred content of aromatic dicarboxylic acid is 50 mol % to 70 mol %.

[0108] Examples of the dialcohol in the polyester resin as the main adhesive component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-cyclohexanediol, and 2-butyl-2-ethyl-1,3-propanediol.

[0109] The molecular weight of the polyester resin is preferably specified such that the number average molecular weight (Mn) is 8,000 to 25,000 and the weight average molecular weight (Mw) is 15,000 to 50,000, with the ratio (Mw / Mn) being 1.3 to 2.5. When the number average molecular weight (Mn) is 8,000 or more and the weight average molecular weight (Mw) is 15,000 or more, adequate coating strength and heat resistance can be obtained, while when the number average molecular weight (Mn) is 25,000 or less and the weight average molecular weight (Mw) is 50,000 or less, the coating will not become too hard and will have adequate coating elongation.

[0110] Furthermore, when the ratio (Mw / Mn) is 1.3 to 2.5, an appropriate molecular weight distribution is achieved, and a balance can be maintained between adhesive application suitability (wide distribution) and performance (narrow distribution).

[0111] The particularly preferred number average molecular weight (Mn) of the polyester resin is 10,000 to 23,000, the particularly preferred weight average molecular weight (Mw) is 20,000 to 40,000, and the particularly preferred (Mw / Mn) is 1.5 to 2.3.

[0112] Furthermore, the molecular weight of the polyester resin can be adjusted by chain extension with a polyfunctional isocyanate. Specifically, when the polyester component in the base resin is linked with NCO, a polymer with terminal hydroxyl groups is produced, and the molecular weight of the polyester resin can be adjusted by adjusting the equivalent ratio between the isocyanate group and the polyester hydroxyl group. In the present invention, it is preferable to use a polyester resin linked so that the equivalent ratio (OH / NCO) is 1.01 to 10. Another method for adjusting the molecular weight is to change the reaction conditions for the condensation polymerization reaction of dicarboxylic acid and dialcohol (adjusting the molar ratio of the dicarboxylic acid and dialcohol).

[0113] Furthermore, in this embodiment, an epoxy resin or an acrylic resin may be added as an additive to the main agent in the adhesive component.

[0114] The polyfunctional isocyanate compound, which is the curing agent of the adhesive component, can be any of various aromatic, aliphatic, and alicyclic isocyanate compounds. Specific examples include polyfunctional isocyanate-modified compounds of one or more diisocyanates, such as aliphatic hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and aromatic tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI).

[0115] Examples of modification methods include adducts with polyfunctional active hydrogen compounds such as water, glycerin, and trimethylolpropane, as well as polyfunctional isocyanate modifications obtained by polymerization reactions such as isocyanuration, carbodiimide formation, and polymerization, and one or more of these can be used in combination. However, in order to increase the adhesive strength after curing and thereby prevent peeling of the base layer 51, it is preferable that the aromatic isocyanate compound be contained in an amount of 50 mol% or more. A more preferable content of the aromatic isocyanate compound is 70 mol% or more.

[0116] In the two-component curing polyester urethane resin adhesive component, the blend ratio of the base agent and curing agent is preferably 1 mole of polyol hydroxyl groups (-OH) to 2 to 25 moles of isocyanate functional groups (-NCO). If the molar ratio (-NCO) / (-OH) is less than 2 and the amount of isocyanate functional groups (-NCO) is small, the curing reaction may not proceed sufficiently, resulting in insufficient coating strength and heat resistance. On the other hand, if the (-NCO) / (-OH) ratio exceeds 25 and the amount of isocyanate functional groups (-NCO) is large, excessive reaction with functional groups other than the polyol may occur, resulting in the coating being too hard and insufficient in elongation. A particularly preferred molar ratio (-NCO) / (-OH) of polyol hydroxyl groups to isocyanate functional groups is 5 to 20.

[0117] It is preferable that the colored adhesive composition composed of an adhesive (two-component curing polyester urethane resin) and a liquid coloring agent (resin, solvent, CB, auxiliary agent) produces a cured film (colored adhesive cured layer) after the reaction that has the following physical properties:

[0118] In order to ensure good formability of the hermetic packaging material and good interlayer bonding strength, the cured film preferably has a Young's modulus of 450 MPa to 700 MPa, particularly preferably 450 MPa to 650 MPa, as determined by a tensile test (JIS K7161-1).

[0119] The breaking strength according to the JIS K7161-1 tensile test is preferably 20 MPa to 60 MPa, and particularly preferably 30 MPa to 50 MPa. Furthermore, the breaking elongation according to the JIS K7161-1 tensile test is preferably 20% to 100%, particularly preferably 20% to 60%, and even more preferably 21% or more.

[0120] Furthermore, it is preferable that the tensile stress-strain curve (SS curve) does not show a decrease in strength before fracture. Figure 5 shows three patterns of SS curves. Pattern A shows a small amount of strain relative to the tensile stress, while pattern B shows a large amount of strain. However, in both cases, the amount of strain increases as the tensile stress increases, and no decrease in strength is observed before fracture. On the other hand, pattern C shows a decrease in tensile stress as the amount of strain increases, and shows a decrease in strength before fracture. In the present invention, it is preferable that the cured film of the two-component curing adhesive does not show a decrease in strength in the SS curve. It is even more preferable that the SS curve does not have an inflection point where the strength changes suddenly.

[0121] The Young's modulus of the cured colored adhesive film in the packaging material of the present invention is higher than that of a cured adhesive film that does not contain a colored pigment because the colored pigment contains a predetermined amount of colored pigment and this colored pigment acts as a reinforcing material, and this higher Young's modulus allows the packaging material of the present invention to achieve good moldability.

[0122] The adhesive containing the two-component curing polyester urethane resin is prepared by polycondensing dicarboxylic acid and dialcohol, which are the raw materials for the polyester resin, and, if necessary, further extending the chains with a polyfunctional isocyanate. This is then mixed with a solvent, a urethane reaction catalyst, a coupling agent for improving adhesive strength, an epoxy resin, an antifoaming agent, a leveling agent, an ultraviolet absorber, an antioxidant, and other various additives to form a fluid polyester resin solution, which is then blended with a polyfunctional isocyanate compound, which serves as a curing agent, or a solvent to prepare a low-viscosity fluid material.

[0123] Below are shown the preferred conditions (1) and (2) for the components in the colored adhesive composition that constitutes the first adhesive layer 61. The content rates listed below are the proportions of solid components that do not include the solvent.

[0124] (1) The preferred content of the color pigment relative to the total amount of the color pigment and polyester resin (the main component of the two-component curing polyester urethane resin) is 2% by mass or more and less than 5% by weight. By keeping the color pigment content less than 5% by weight, delamination of a substrate layer such as an ONY (biaxially oriented nylon) film can be sufficiently suppressed even in harsh environments such as high-temperature and humidity environments and hot water immersion environments.

[0125] (2) The coating amount of the colored adhesive composition as the first adhesive layer 61 is 5 g / m 2 ~10g / m 2 be.

[0126] Based on the above (1) and (2), the content of the color pigment contained in the first adhesive layer 61 is 0.1 g / m 2 More than 0.5g / m 2 The color pigment is in the range of less than 0.25 g / m 2 If the content of the coloring pigment is less than 0.45 g / m, the shielding effect and visual effect will be insufficient, which may cause problems in terms of design, and is therefore undesirable. 2 If the content exceeds 0.25 g / m, the improvement in the visual effect is almost eliminated, and peeling may occur more easily in the hot water immersion test described later. Therefore, the effective content range of the color pigment contained in the first adhesive layer 61 of the present invention is 0.25 g / m 2 ~0.45g / m 2 The more preferred range of the color pigment content is 0.25 g / m 2 ~0.35g / m 2 The range is.

[0127] After forming the battery packaging, if a 45°C hot water immersion test is conducted as the most severe environmental test, the color pigment content must be 0.45 g / m 2If the temperature exceeds this range, the first adhesive layer 61 becomes hard and brittle, the adhesive strength to the metal foil layer 52 decreases, and this may cause the base layer (heat-resistant resin layer) 51 to peel off in a hot water immersion test.

[0128] However, in a general environmental test after forming the battery packaging (high temperature and high humidity storage test at 70°C x 90% RH), the content of color pigment is 0.5 g / m 2 If the temperature is less than this, the base layer (heat-resistant resin layer) 51 will not peel off during the storage test and can be used.

[0129] The content of color pigment is 0.5g / m 2 In the above cases, there is a high possibility that the base layer 51 will peel off during the high-temperature, high-humidity storage test.

[0130] The coating amount of the first adhesive layer (colored adhesive composition) 61 is 5 g / m 2 If it is less than this, the content of the color pigment will be small, and as mentioned above, the effect of hiding the metal foil layer will be small, and furthermore, the metallic luster may be visible, which may impair the profound feeling.

[0131] The coating amount of the first adhesive layer 61 is 10 g / m 2 If the amount exceeds 1000 ppm, the processability will be significantly deteriorated, leading to an increase in costs. The preferred coating amount of the colored adhesive composition is 6 g / m 2 ~10g / m 2 is.

[0132] The method for bonding the metal foil layer 52 and the base layer 51 is not limited, but a method called dry lamination is recommended. Specifically, the colored adhesive composition prepared as described above is applied to the upper surface (outer surface) of the metal foil layer 52 or the lower surface (inner surface) of the base layer 51, or both of these surfaces, and the solvent is evaporated to form a dry film, after which the metal foil layer 52 and the base layer 51 are bonded together. This is then further cured according to the curing conditions of the two-component curing polyester urethane resin. As a result, the metal foil layer 52 and the base layer 51 are bonded together via the first adhesive layer 61. Examples of methods for applying the colored adhesive composition include gravure coating, reverse roll coating, and lip roll coating.

[0133] The second adhesive layer (non-colored adhesive layer) 62 is not particularly limited, but examples include adhesive layers formed from polyurethane adhesives, acrylic adhesives, epoxy adhesives, polyolefin adhesives, elastomer adhesives, fluorine adhesives, acid-modified polypropylene adhesives, etc.

[0134] Among these, it is preferable to use an acrylic adhesive or a polyolefin adhesive, in which case the electrolyte resistance and water vapor barrier properties of the packaging material 1 can be improved.

[0135] The method for bonding the metal foil layer 52 and the sealant layer 53 is not limited, but an example is a dry lamination method in which an adhesive that constitutes the second adhesive layer 62 is applied and dried, and then the layers are bonded together, similar to the bonding of the metal foil layer 52 and the base material layer 51 described above.

[0136] The matte coating layer 50 is laminated on the outer surface of the base material layer 51, and is a layer that imparts good slipperiness to the surface of the packaging material 1 and improves formability.

[0137] The matte coat layer 50 is made of a resin composition containing inorganic fine particles dispersed in a heat-resistant resin component. In particular, the matte coat layer 50 is preferably made of a resin composition containing a two-component curing heat-resistant resin containing 0.1% to 1% by mass of inorganic fine particles with an average particle size of 1 μm to 10 μm. Examples of heat-resistant resins include acrylic resins, epoxy resins, polyester resins, urethane resins, polyolefin resins, and fluorine-based resins. Fluorine-based resins based on tetrafluoroethylene or fluoroethylene vinyl ether are preferred because of their excellent heat resistance and chemical resistance. Examples of inorganic fine particles include, but are not limited to, silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, and calcium silicate. Of these, silica is preferred.

[0138] The matte coat layer 50 is formed by applying a matte coat composition containing the inorganic fine particles and heat-resistant resin described above to the surface of the base layer 51 and curing it.

[0139] The thickness of the matte coating layer 50 after curing is preferably in the range of 0.5 μm to 5 μm. If it is thinner than this lower limit, the effect of improving slipperiness cannot be expected, and if it is thicker than this upper limit, there is a risk of increased costs, which is not preferable. A particularly preferable thickness is in the range of 1 μm to 3 μm.

[0140] The gloss value of the surface of the matte coating layer 50 is preferably set to 1% to 15% as measured at a 60° reflection angle in accordance with JIS Z8741. The gloss value is obtained by measuring at a 60° reflection angle using, for example, a gloss measuring device "micro-TRI-gloss-s" manufactured by BYK.

[0141] The timing of the process of forming the matte coat layer 50 is not limited, but it is preferable to perform the process following the process of bonding the base layer 51 to the metal foil layer 52 via the first adhesive layer 61. Currently, this process is performed after bonding a non-oriented polypropylene (CPP) film to the base layer 51.

[0142] In the above embodiment, the sealing packaging material of the present invention has been described as being used as an exterior material for a battery or other electricity storage device, but the present invention is not limited to this and can also be used as a packaging material for sealing and sealing contents such as food and medicine.

[0143] In the above embodiment, a case has been described in which a sheet-like exterior material (packaging material) 1 is used as the cover member 3, but this is not limiting, and in the present invention, the cover member 3 may be molded. For example, the cover member may be formed of a molded product with a hat-shaped cross section, with a central portion recessed (bulged) upward, and the outer periphery of this hat-shaped cover member may be integrally joined to cover the tray member from above. Furthermore, in the present invention, a casing may be formed by overlapping two unmolded sheet-like exterior materials (packaging materials) 1 so as to sandwich the electricity storage device main body, and heat-sealing their outer peripheries.

[0144] In addition, in the above embodiment, an example is given in which two sheets of exterior material (outer laminate material) are used to form the casing, but this is not limited to this, and in the present invention, the number of sheets of exterior material forming the casing is not limited, and may be one sheet or three or more sheets.

[0145] Needless to say, the packaging material of the present invention does not necessarily need to have the matte coating layer 50, the chemical conversion coating layer 63, etc., which are preferred requirements. [Example]

[0146] Next, examples that include the gist of the present invention and comparative examples for deriving the effects thereof will be described. Needless to say, the present invention is not limited to the following examples.

[0147] In the following Examples 1 to 8 and Comparative Examples 1 to 5, packaging materials (packaging materials) having the laminated structure shown in Fig. 3 were produced. As shown in Table 1, the examples and comparative examples have the same configuration except for the configuration of the first adhesive layer (adhesive layer for coloring).

[0148] [Table 1]

[0149] Example 1 A 35 μm thick aluminum foil made according to JIS H4160 A8079 was prepared as the metal foil layer. A chemical conversion treatment solution consisting of polyacrylic acid, a trivalent chromium compound, water, and alcohol was applied to both sides of the aluminum foil, followed by drying at 150°C to form a chemical conversion coating. The chromium deposition amount of this chemical conversion coating was 10 mg / m 2 is.

[0150] A biaxially oriented nylon film having a thickness of 15 μm was prepared as the substrate layer, and the surface (lower surface) of this film to be bonded to the first adhesive layer was subjected to a corona treatment.

[0151] The biaxially oriented nylon film used as the base layer had a TD hot water shrinkage of 3.8%, a MD hot water shrinkage of 2.3%, and a difference in hot water shrinkage between TD and MD (TD-MD) of The polyamide has a viscosity of 1.5%, a TD modulus of elasticity of 1.5 GPa, an MD modulus of elasticity of 2.0 GPa, a TD breaking strength of 322 MPa, an MD breaking strength of 281 MPa, and a number average molecular weight of 18,000.

[0152] The colored adhesive composition constituting the first adhesive layer was prepared by the following method using a two-component curing polyester urethane resin as the adhesive component and carbon black as the color pigment.

[0153] First, a polyester resin (polyester polyol) was prepared as the base material for the two-component curing polyester urethane resin. This base material was prepared by melting 30 mol parts neopentyl glycol, 30 mol parts ethylene glycol, and 40 mol parts 1,6-hexanediol at 80°C. While stirring, 30 mol parts adipic acid (4 methylene units), an aliphatic dicarboxylic acid, and 70 mol parts isophthalic acid, an aromatic dicarboxylic acid, were added to the melt at 210°C for 20 hours to produce a polyester polyol. This polyester polyol had a number-average molecular weight (Mn) of 12,000, a weight-average molecular weight (Mw) of 20,500, and a ratio (Mw / Mn) of 1.7. 60 mol parts ethyl acetate was then added to 40 mol parts of this polyester polyol to produce a fluid polyester polyol resin solution. The hydroxyl value was 2.2 mgKOH / g (solution value).

[0154] Separately, 20 parts by mass of the same polyester polyol as above was mixed as a vehicle resin, 40 parts by mass of ethyl acetate as a vehicle solvent, 35 parts by mass of carbon black having an average particle size of 1.0 μm as a colorant, and 5 parts by mass of a pigment dispersant and an anti-settling agent as other auxiliaries, and this mixture was kneaded in a disperser to prepare a high-concentration carbon black ink (black ink with a carbon black content of 35% by mass).

[0155] Next, 100 parts by weight of the polyester polyol resin solution, 64.4 parts by weight of ethyl acetate, and the required amount of the high-concentration carbon black ink were blended, and the carbon black ink was dispersed using a pigment disperser to obtain a base adhesive agent containing a colored pigment (carbon black). Then, 7.1 parts by weight of an adduct of the aromatic isocyanate compound tolylene diisocyanate (TDI) (aromatic) and trimethylolpropane (NCO 13.0%, solids 75%) was blended with 100 parts by weight of this base agent containing a colored pigment as a curing agent, and 34.1 parts by weight of ethyl acetate was added and stirred thoroughly to obtain a colored adhesive composition. In this colored adhesive composition, the molar ratio (-NCO) / (-OH) of the isocyanate functional group (-NCO) to the polyester polyol hydroxyl group (-OH) was 10. As shown in Table 1, the pigment concentration in this colored adhesive composition was 2.5% by weight.

[0156] A cured film (cured colored adhesive film) was prepared using the above colored adhesive composition, and its physical properties were evaluated. Specifically, the colored adhesive composition was applied to a non-adhesive untreated PP film so that the thickness after drying was 10 μm, and after drying the solvent, the composition was cured by aging at 60° C. until the residual isocyanate was 5% or less. The cured film was peeled from the untreated PP film and cut into 15 mm widths to prepare test pieces.

[0157] The prepared test specimen was subjected to a tensile test with a gauge length of 50 mm and a tensile speed of 100 mm / min to measure the Young's modulus, breaking strength, and breaking elongation. The Young's modulus was 460 MPa, the breaking strength was 32 MPa, and the breaking elongation was 23%. The SS curve obtained from this tensile test was pattern A shown in Figure 5.

[0158] On the other hand, a polyacrylic adhesive was prepared as the second adhesive layer, and an unstretched polypropylene film with a thickness of 30 μm was prepared as the sealant layer.

[0159] For the matte coat layer, a composition for the matte coat layer was prepared by mixing 70 parts by weight of fluoroethylene vinyl ester as a heat-resistant resin, 10 parts by weight of barium sulfate and 10 parts by weight of powdered silica as inorganic microparticles, 5 parts by weight of polytetrafluoroethylene wax as a wax, and 5 parts by weight of polyethylene resin beads as resin beads.

[0160] A predetermined amount of the colored adhesive composition was applied to one surface (outer surface) of the aluminum foil for the metal foil layer, which had a chemical conversion coating formed on both surfaces, and dried to form a first adhesive layer (cured colored adhesive film). The amount of the colored adhesive composition applied, the number average molecular weight Mn, the weight average molecular weight Mw, Mw / Mn, and the carbon black content (applied amount) are shown in Table 1. The film for the base layer was then attached to the first adhesive layer to form a base layer, and the resulting film was aged for 5 days in a 60°C environment.

[0161] Next, the polyacrylic adhesive as a second adhesive layer was applied to the other surface (lower surface) of the metal foil layer, and the polypropylene film as a sealant layer was attached to the lower surface (inner surface) of the second adhesive layer.

[0162] Furthermore, the above-mentioned composition for a matte coat layer was applied to the outer surface of the base material layer so that the thickness after drying would be 2 μm.

[0163] The laminate thus bonded was left to age in an environment of 40°C for 5 days, thereby obtaining a packaging material of Example 1 (external packaging material for an electricity storage device).

[0164] <Examples 2 to 7 and Comparative Examples 1 to 4> As shown in Table 1, in the first adhesive layer, the pigment concentration (carbon black concentration), colored adhesive composition coating amount, pigment coating amount (content), number average molecular weight Mn, weight average molecular weight Mw, and Mw / Mn were adjusted, and otherwise the packaging materials of Examples 2 to 7 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1 above.

[0165] <Evaluation test> (1) Evaluation of concealment (shielding) Each packaging material of the Examples and Comparative Examples was visually observed from the substrate layer side (outer surface side) to confirm the concealing ability of the metal foil layer. Those with concealing ability were evaluated as "Good", and those without concealing ability were evaluated as "Poor". The evaluation results thus obtained are shown in Table 1.

[0166] (2) Evaluation of formability A press machine manufactured by Amada Co., Ltd. was prepared, equipped with a die having a punch shape of 33 mm x 54 mm, punch corner R: 2 mm, punch shoulder R: 1.3 mm, and die shape die shoulder R: 1 mm.

[0167] Each packaging material of the examples and comparative examples was sampled in a blank shape of 100 mm x 125 mm, and each sample was deep-drawn using the above press to produce a molded product sample.

[0168] The corners of each molded product obtained by this deep drawing were checked for pinholes and cracks, and the "maximum forming depth (mm)" at which pinholes and cracks did not occur was examined and evaluated based on the following criteria. The presence or absence of cracks and pinholes was examined using a light transmission method in a darkroom. Of the evaluation criteria "◎", "○", and "×" explained below, "◎" and "○" are pass and "×" is fail. The results are shown in Table 1.

[0169] ◎: No cracks or pinholes with a molding depth of 6mm or more ○: Forming depth is 5mm or more and less than 6mm, no cracks or pinholes ×: Cracks or pinholes present at molding depth of less than 5 mm (3) Evaluation of peeling Each packaging material of the Examples and Comparative Examples was sampled to a predetermined size, and each sample was deep-drawn in the same manner as above to produce a molded case (upside-down tray-shaped member) 2 as a molded product having a recessed portion (protruding portion) 21 of 33 mm × 54 mm × 4.5 mm and a flat flange portion 22 on the outer periphery of the protruding portion, as shown in Figure 6. Furthermore, after the top wall (top surface) 25 of the protruding portion of the molded product 2 was subjected to concave deformation so as to be crushed, the following high-temperature high-humidity test and warm water immersion test were performed, and the presence or absence of peeling of the base material layer after the tests was visually observed.

[0170] In the high temperature and high humidity test, the molded product 2 with the top surface 25 crushed was stored in an atmosphere of 70°C temperature and 90% humidity for two weeks to check for peeling of the base layer. In the hot water immersion test, the crushed molded product 2 was submerged in hot water at 45°C and stored for two weeks.

[0171] In both tests, 30 molded articles 2 were visually observed for each Example and Comparative Example, and evaluated based on the number of molded articles 2 in which the base layer peeled from the metal foil layer according to the following criteria. Of the following evaluation criteria, "◎", "○", "△", and "×", "◎", "○", and "△" indicate passing, and "×" indicates failing. The results are shown in Table 1.

[0172] ◎: 0 out of 30 pieces peeled off ○: Peeling occurred in 1 or 2 out of 30 pieces △: 3 to 5 out of 30 peeled off ×: Peeling occurred in 6 to 30 out of 30 pieces. <Overall rating> As is clear from the above evaluation results, the packaging materials (exterior materials) of the Examples related to the present invention were evaluated as excellent in all of shielding property, formability, and peel resistance. In contrast, the packaging materials of the Comparative Examples, which deviate from the gist of the present invention, were inferior to the packaging materials of the Examples in all of the evaluations. [Industrial Applicability]

[0173] The packaging material of the present invention can be suitably used as an exterior material for batteries (electricity storage devices) such as notebook computers, mobile phones, in-vehicle (mobile) or stationary secondary batteries (lithium ion secondary batteries), etc. [Explanation of symbols]

[0174] 1: Exterior material (packaging material) 10: Energy storage device body 2: Tray components (packaging materials, exterior materials, packaging containers) 21: Recessed portion (molded portion) 3: Covering materials (packaging materials, exterior materials) 51: Base material layer 52: Metal foil layer 53: Sealant layer 61: First adhesive layer (colored adhesive layer, colored adhesive composition, colored adhesive cured film) 63: Chemical coating

Claims

1. A packaging material comprising a metal foil layer laminated inside a heat-resistant resin base layer, and a thermoplastic resin sealant layer laminated inside the metal foil layer, wherein a colored adhesive layer is provided between the metal foil layer and the base layer, The aforementioned colored adhesive layer is composed of a colored adhesive cured film containing a colored pigment and an adhesive. The aforementioned colored adhesive cured film is a packaging material characterized by having a Young's modulus of 450 MPa to 700 MPa as determined by a tensile test according to JIS K7161-1:2014.

2. The packaging material according to claim 1, wherein the colored adhesive cured film has a breaking elongation of 21% to 60% as determined by a tensile test according to JIS K7161-1:2014.

3. The colored adhesive layer contains 2% by mass or more and less than 5% by mass of the colored pigment. The aforementioned colored adhesive layer is 5 g / m² ２ ~10g / m ２ The packaging material according to claim 1 or 2, wherein the colored adhesive cured film is the colored adhesive cured film.

4. The adhesive in the colored adhesive layer comprises a two-component curable polyester urethane resin derived from a polyester resin as the main component and a polyfunctional isocyanate compound as the curing agent. The polyester resin used as the main component has a number-average molecular weight (Mn) of 8,000 to 25,000 and a weight-average molecular weight (Mw) of 15,000 to 50,000, with a ratio of these (Mw / Mn) of 1.3 to 2.

5. The packaging material according to claim 1 or 2, wherein the polyfunctional isocyanate compound used as a curing agent contains 50 mol% or more of an aromatic isocyanate.

5. In the aforementioned two-component curable polyester urethane resin, the polyester resin used as the main component is made from a dicarboxylic acid and a dialcohol. The packaging material according to claim 4, wherein the dicarboxylic acid comprises an aliphatic dicarboxylic acid having an even number of methylene groups in the methylene chain and an aromatic dicarboxylic acid, and the content of the aromatic dicarboxylic acid relative to the total amount thereof is 40 mol% to 80 mol%.

6. The packaging material according to claim 1 or 2, wherein the metal foil layer has a chemical conversion coating on at least one surface thereof.

7. The packaging material according to claim 1 or 2, wherein a matte coat layer is provided on the outer surface of the base material layer.

8. A packaging container characterized in that a molded portion is formed by deep drawing or stretch molding in the packaging material according to claim 1 or 2.

9. An outer casing material for an energy storage device, characterized by being composed of the packaging material described in claim 1 or 2.

10. The main unit of the energy storage device, The exterior material is as described in claim 9, An energy storage device characterized in that the main body of the energy storage device is enclosed with the exterior material.

11. A method for producing a colored adhesive composition constituting a colored adhesive cured film in a packaging material according to claim 1 or 2, The aforementioned coloring pigments are mixed with the vehicle to prepare a liquid colorant. Of the main component and curing agent that make up the adhesive, the liquid colorant is mixed with the main component to prepare a main component for a pigment-containing adhesive, A method for producing a colored adhesive composition, characterized in that the main component for the pigment-containing adhesive and the curing agent are blended together to produce the colored adhesive composition.

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