Packaging material

Abstract

To provide a packaging material excellent in formability, colorability and strength.SOLUTION: The present invention is directed to a packaging material comprising a metal foil layer 52 laminated inside a base material layer 51 and a sealant layer 53 laminated inside the metal foil layer 52, and a colored adhesive layer 61 provided between the metal foil layer 52 and the base material layer 51. The base material layer 51 has both TD hydrothermal shrinkage and MD hydrothermal shrinkage of 2.0% to 5.0%, a difference between the TD hydrothermal shrinkage and MD hydrothermal shrinkage of 1.5% or less, and both TD modulus and MD modulus of 1.5 GPa to 3 GPa. The colored adhesive layer 61 is composed of a colored adhesive composition containing a colored pigment and an adhesive, the colored adhesive layer 61 is a colored adhesive composition having an abundance of 5 g / m2 to 10 g / m2, and the colored adhesive composition contains a colored pigment of 0.25 g / m2 to 0.49 g / m2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to packaging materials used as outer coverings for batteries (energy storage devices) such as laptop computers, mobile phones, in-vehicle (mobile) or stationary secondary batteries (lithium-ion secondary batteries), as well as packaging materials, packaging containers, and energy storage devices for food and pharmaceuticals. [Background technology]

[0002] Batteries such as lithium-ion rechargeable batteries are increasingly required to be colored to match the appearance and color of the electrical equipment they are installed in. In particular, to give the equipment a sense of solidity and luxury, it is common to paint the equipment black, and in such cases, the batteries are also often painted black.

[0003] For packaging materials of this type of device, it is common to use a laminate in which resin layers are laminated on both sides of a metal foil. When coloring the battery black or the like, there are several methods, such as coloring the resin layer used in the packaging material, providing a printed layer beneath the base material layer, coloring the adhesive layer between the base material layer and the metal layer, or coloring the adhesive layers between layers if the base material layer consists of multiple layers.

[0004] For example, some battery casing materials have a layer containing an identification mark on one of the layers: the base layer (resin layer), the adhesive layer, or the metal foil layer. In some cases, a printed layer or adhesive layer provided on the underside of the base layer is colored, thereby coloring the entire packaging material (see Patent Documents 1 and 2).

[0005] Furthermore, some battery casing materials have a blackbody material layer between the metal foil layer and the outer film to promote heat dissipation (see Patent Document 3). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication WO 2011 / 016506 A1 [Patent Document 2] Japanese Patent Publication No. 2011-054563 [Patent Document 3] Japanese Patent Publication No. 2011-096552 [Overview of the project] [Problems that the invention aims to solve]

[0007] Conventionally, when coloring the aforementioned packaging material black, it is common to apply a printed layer using printing ink containing pigments such as carbon black.

[0008] However, when a printed layer containing carbon black as a pigment is provided on the inner surface of the outer resin layer that makes up the battery casing in order to color the battery black, the following problems arose.

[0009] In other words, when the above-mentioned black packaging material is molded into the shape of a molded container (molded case) by deep drawing or stretch molding, the carbon black-containing printing layer partially cracks and peels off, exposing the non-black base layer and making it visible, which is a problem as it impairs the uniformity of the black color.

[0010] Such partial peeling of the printed layer can occur when sealing the black packaging material after the electrodes and electrolyte have been sealed inside, or when batteries packaged in black packaging material are used in somewhat harsh environments such as high temperature and humidity.

[0011] Furthermore, the same problem occurred not only with black packaging materials using carbon black, but also with packaging materials colored with other pigments, making it difficult to achieve good colorability.

[0012] On the other hand, in recent years, batteries such as lithium-ion secondary batteries have been increasing in capacity, and packaging materials used as battery casings are increasingly required to have good moldability, heat resistance, and moisture resistance. Furthermore, it is highly desirable that the heat-resistant resin layer (base layer) on the outer surface of the battery casing be able to efficiently distribute external forces during molding and maintain sufficient strength.

[0013] The present invention has been made in view of the above problems, and an object thereof is to provide a packaging material excellent in formability, coloring property and strength, a packaging container using the packaging material, an exterior material for a power storage device, and a power storage device.

Means for Solving the Problems

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

[0015] [1] A packaging material including a metal foil layer laminated inside a base material layer made of a heat-resistant resin and a sealant layer made of a thermoplastic resin laminated inside the metal foil layer, wherein a colored adhesive layer is provided between the metal foil layer and the base material layer, wherein the base material layer has a hot water shrinkage rate in the TD direction and a hot water shrinkage rate in the MD direction both of 2.0% to 5.0%, wherein the difference between the hot water shrinkage rate in the TD direction and the hot water shrinkage rate in the MD direction of the base material layer is 1.5% or less, wherein the base material layer has an elastic modulus in the TD direction and an elastic modulus in the MD direction both of 1.5 GPa to 3 GPa, wherein the colored adhesive layer is composed of a colored adhesive composition containing a colored pigment and an adhesive, wherein the colored adhesive layer is the colored adhesive composition of 5 g / m ~10 g / m 2 and wherein the colored adhesive layer contains 0.25 g / m 2 ~0.49 g / m 2 of the colored pigment, and is characterized as the packaging material.

[0016] [2] The colored adhesive layer contains a two-component curable polyester urethane resin composed of a polyester resin as a main component and a polyfunctional isocyanate compound as a curing agent, wherein the polyester resin as the main component has a number average molecular weight (Mn) of 8,000 to 25,000, a weight average molecular weight (Mw) of 15,000 to 50,000, and a ratio (Mw / Mn) of 1.3 to 2.5, The polyfunctional isocyanate compound used as a curing agent contains 50 mol% or more of aromatic isocyanate. The packaging material according to item 1, wherein the base layer is composed of a polyamide film having a number average molecular weight of 15,000 to 30,000.

[0017] [3] In the two-component curable polyester urethane resin, the polyester resin as the main component is made from a dicarboxylic acid and a dialcohol, The packaging material according to item 2 above, 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%.

[0018] [4] The cured film of the two-component curable polyester urethane resin is the packaging material according to item 2 or 3 above, wherein the Young's modulus determined by a tensile test in accordance with JIS K7162 is 70 MPa to 400 MPa.

[0019] [5] The packaging material according to any one of paragraphs 1 to 4 above, wherein the metal foil layer has a chemical conversion coating on at least one surface thereof.

[0020] [6] The packaging material according to any one of items 1 to 5 above, wherein a matte coat layer is provided on the outer surface of the base material layer.

[0021] [7] The packaging material according to any one of paragraphs 1 to 6 above, wherein the base material layer has a breaking strength of TD and a breaking strength of MD of 320 MPa or more.

[0022] [8] A packaging container characterized in that a molded portion is formed by deep drawing or stretch molding in the packaging material described in any one of paragraphs 1 to 7 above.

[0023] [9] An outer material for an energy storage device, characterized in that it is composed of the packaging material described in any one of paragraphs 1 to 7 above and / or the packaging container described in paragraph 8 above.

[0024]

[10] The main body of the energy storage device, The exterior material described in item 9 above is included, An energy storage device characterized in that the main body of the energy storage device is enclosed with the exterior material. [Effects of the Invention]

[0025] According to the packaging material of Invention [1], good colorability can be obtained because the colored adhesive layer contains a pigment. Furthermore, since the thermal shrinkage rate and elastic modulus between the TD and MD of the base layer are specified within a predetermined range, the effects from external pressure can be efficiently dispersed, and sufficient strength and excellent moldability can be obtained. Furthermore, since the amount of colored adhesive layer applied and the content of colored pigment are specified within a predetermined range, uniform colorability can be obtained overall, weakening of the colored adhesive layer due to the content of colored pigment can be prevented, and sufficient adhesion between the base layer and the metal foil layer can be maintained. As a result, deep molding with a sharp shape is possible, and defects such as partial cracking and peeling of the colored adhesive layer can be prevented during molding and sealing, or when used in harsh environments of high temperature and humidity. Moreover, even in the hot water immersion test, which is the most severe environmental test, the base layer does not peel off, and the adhesion of the base layer can be further improved.

[0026] According to the packaging material of Invention [2], the colored adhesive layer contains a specific two-component curable polyester urethane resin, thereby providing appropriate strength and elongation, as well as excellent heat resistance. Furthermore, the polyester resin, which is the main component of the colored adhesive layer, is adjusted to a predetermined molecular weight distribution, resulting in excellent adhesive application suitability. In addition, the polyamide film used as the base layer is adjusted to a predetermined molecular weight distribution, making the film less prone to tearing and providing good puncture resistance.

[0027] According to the packaging material of the invention [3], the two-component curable polyester urethane resin contained in the colored adhesive layer is composed of a specific composition of polyester resin as the main component, thereby providing even better adhesion and more reliably preventing delamination between the base material layer and the metal foil layer.

[0028] According to the packaging material of the invention [4], the Young's modulus of the cured film of the two-component curable polyester urethane resin contained in the colored adhesive layer is adjusted, thereby maintaining appropriate flexibility and coating strength, and more reliably preventing delamination between the substrate layer and the metal foil layer.

[0029] According to the packaging material of the invention [5], since a chemical conversion coating is provided on the surface of the metal foil layer, corrosion of the metal foil layer can be prevented, and the corrosion resistance of the entire packaging material can be improved.

[0030] According to the packaging material of the invention [6], since a matte coat layer is provided on the surface of the base material layer, moldability and durability can be further improved, and the presence of the matte coat layer improves the appearance quality of the packaging material, prevents problems such as adhesion between packaging materials, and facilitates the handling of packaged products.

[0031] According to the packaging material of the invention [7], the strength can be further improved because the breaking strength is specified within a predetermined range.

[0032] According to the packaging container of the invention [8], since it utilizes the packaging material of the above invention, the same effects as above can be obtained.

[0033] According to the exterior material for energy storage devices of the invention [9], since it utilizes the packaging material and packaging container of the above invention, the same effects as above can be obtained.

[0034] According to the energy storage device of the invention

[10] , since it utilizes the exterior material of the above invention, the same effects as above can be obtained. [Brief explanation of the drawing]

[0035] [Figure 1] Figure 1 is a side cross-sectional view showing an energy storage device that is an embodiment of this invention. [Figure 2] Figure 2 is a perspective view showing an exploded view of the energy storage device of an embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing an exterior material for an energy storage device according to an embodiment. [Figure 4] Figure 4 is a schematic diagram illustrating the MD and TD of the resin film. [Figure 5] Figure 5 shows the SS curve of the cured film of a two-component polyester urethane resin adhesive. [Figure 6] Figure 6 is a perspective view showing a molded product of a packaging material sample used in an embodiment of this invention. [Modes for carrying out the invention]

[0036] Figure 1 is a side cross-sectional view showing an embodiment of the energy storage device of this invention, and Figure 2 is a perspective view showing the embodiment of the energy storage device in an exploded view.

[0037] As shown in both figures, the energy storage device of this embodiment comprises a casing 11 and an energy storage device body 10, such as an electrochemical element, housed inside the casing 11.

[0038] The casing 11 is composed of a tray member (packaging container) 2, which is rectangular in plan view and formed by the outer material 1, and a cover member 3, which is rectangular in plan view and formed by the outer material (packaging material) 1.

[0039] The tray member 2 is made of a molded product formed from the outer material 1 using a method such as deep drawing. The tray member 2 has a recess formed downwards throughout the entire intermediate region except for the outer peripheral edge, forming a rectangular recessed portion 21 in plan view, and an outwardly protruding flange portion 22 is integrally formed on the outer circumference of the opening edge of the recessed portion 21.

[0040] The cover member 3 is made of an exterior material 1 formed in a sheet shape. The outer 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.

[0041] The outer packaging material 1, which serves as both the tray member 2 and the cover member 3, is made of an outer packaging laminate, which is a flexible and pliable laminate sheet or film.

[0042] Furthermore, the energy storage device body 10 is not particularly limited, but examples include a battery body, a capacitor body, a capacitor body, etc. The energy storage device body 10 is formed in a shape that corresponds to the recessed portion 21 of the tray member 2.

[0043] With the energy storage device body 10 housed within the recessed portion 21, the cover member 3 is positioned on the tray member 2 so as to cover the recessed portion 21, and the flange portions 22 and 32 of the tray member 2 and the cover member 3 are heat-fused together to form the energy storage device of this embodiment.

[0044] Although not shown in the diagram, one end (inner end) of the tab lead is connected to the main body of the energy storage device 10, while the other end (outer end) is extended to the outside of the energy storage device, allowing electricity to be supplied to and supplied from the main body of the energy storage device 10 via the tab lead.

[0045] Figure 3 is a schematic cross-sectional view illustrating the basic structure of the outer laminate material constituting the exterior material 1 in this embodiment. As shown in the figure, the exterior material (laminate material) 1 used in this embodiment comprises a base layer (heat-resistant resin layer) 51, a metal foil layer (barrier layer) 52 bonded to one surface (inner surface) of the base layer 51 via a first adhesive layer 61 as a colored adhesive layer or an 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 as an inner adhesive layer. Chemical conversion films 63, 63 are formed on both sides of the metal foil layer 52, and a matte coat layer 50 is laminated on the outer surface of the base layer 51.

[0046] In this embodiment, the base layer 51 can be a polyamide film, a polyester film, or the like, and stretched versions of these films are used. In particular, biaxially oriented polyamide film, biaxially oriented polybutylene terephthalate (PBT) film, biaxially oriented polyethylene terephthalate (PET) film, or biaxially oriented polyethylene naphthalate (PEN) film is preferred in terms of moldability and strength.

[0047] Other examples of polyamide films include nylon 6 film, nylon 6,6 film, and MXD nylon film.

[0048] The base layer 51 may be formed as a single layer or as multiple layers. In the case of multiple layers, a multilayer structure consisting of a PET film / polyamide film can be exemplified.

[0049] It is desirable to apply an easy-adhesion treatment to the lower surface of the stretched film used as the base layer 51, that is, the surface that is bonded to the first adhesive layer 61, in order to improve the adhesive strength with the adhesive 61.

[0050] Various proposals have been made regarding easy-adhesion treatments, and the following treatments can be cited as examples.

[0051] At least one surface of the stretched film, which serves as the base layer 51, is oxidized by methods such as corona treatment, plasma treatment, flame plasma treatment, electron beam irradiation, and ultraviolet irradiation, while also improving its wettability.

[0052] Another method for imparting wettability involves forming an easy-adhesion treatment layer. For example, an easy-adhesion treatment layer can be formed by applying an aqueous emulsion (water-based emulsion) of one or more resins selected from the group consisting of epoxy resin, urethane resin, acrylic ester resin, methacrylic ester resin, and polyethyleneimine resin to the surface of a stretched film for the substrate layer and then drying it. The application amount (formation amount) is 0.01 g / m² of the solid component.2 ~0.5g / m 2 A certain degree is desirable.

[0053] The application method is not particularly limited, but examples include the spray coating method, gravure roll coating method, reverse roll coating method, and lip coating method.

[0054] In response to the demands for higher capacity and improved safety of energy storage devices (batteries), the base layer 51 of the exterior material for energy storage devices is desired to have even higher moldability and puncture resistance. Research by the inventors has shown that polyamide film is more suitable than polyester film for improving the latter performance (puncture resistance), and more preferably, good moldability and puncture resistance can be obtained by using a polyamide film that satisfies the following physical properties (1) to (5).

[0055] (1) The base layer 51 needs to have both the TD and MD hot water shrinkage rates adjusted to 2.0% to 5.0%, preferably to 2.5% to 4.5%.

[0056] Here, as shown in Figure 4, "MD" refers to the molding direction (resin flow direction) of the resin film F, and "TD" refers to the direction perpendicular to MD. Furthermore, the hot water shrinkage rate is the dimensional change rate in the shrinkage direction (stretching direction) before and after immersion when the film (object to be measured) is immersed in 100°C hot water for 5 minutes. For example, if the dimension in the shrinkage direction (MD or TD) before hot water immersion is "X" and the dimension in the shrinkage direction (MD or TD) after hot water immersion is "Y", the hot water shrinkage rate (%) in the shrinkage direction (MD or TD) can be calculated using the relationship {(XY) / X} × 100. In this invention, it is preferable to use the average value of the hot water shrinkage rate (average hot water shrinkage rate) as the "hot water shrinkage rate" that indicates the characteristic value of the polyamide film. In this invention, the average hot water shrinkage rate is the average value of the hot water shrinkage rates at three points: two points at both ends and one point in the center, for one direction of the sheet (film) to be measured. However, in this invention, depending on the size of the energy storage device body 10, it is also possible to use a "thermal shrinkage rate" that is measured at a specific location (thermal absorption rate at a reference location) rather than an average value as the "thermal shrinkage rate" that indicates the characteristic value of the polyamide film.

[0057] (2) The difference between the hydrothermal shrinkage rate of MD and the hydrothermal shrinkage rate of TD of the base layer 51 must be adjusted to 1.5% or less, preferably to 1.2% or less. Specifically, when the average hydrothermal shrinkage rate of MD is "MDz" and the hydrothermal shrinkage rate of TD is "TDz", the relationship |MDz-TDz|≦1.5% must be satisfied, preferably to |MDz-TDz|≦1.2% or less.

[0058] (3) The modulus of elasticity of both the MD and TD of the base layer 51 must be adjusted to 1.5 GPa to 3 GPa, and preferably to 2.0 GPa to 2.5 GPa.

[0059] (4) It is preferable to adjust at least one of the tensile strength of TD and MD in the base layer 51 to 320 MPa or higher, and more preferably to 400 MPa or lower.

[0060] (5) The number average molecular weight of the nylon polyamide film constituting the base layer 51 is preferably adjusted to 15,000 to 30,000, and more preferably to 20,000 to 25,000.

[0061] In this embodiment, since the hot water shrinkage rates of TD and MD are 2.0% or more, they possess appropriate flexibility, ensuring good moldability as the base layer 51. Furthermore, because they are 5.0% or less, the base layer 51 avoids excessive flexibility and maintains the desired strength.

[0062] Furthermore, in this embodiment, since the difference in the thermal shrinkage rates of TD and MD is adjusted to within the specified range described above, it becomes possible to efficiently distribute the force from external pressure, and the desired strength can be reliably maintained for the base layer 51.

[0063] Furthermore, since the moduli of elasticity of TD and MD are adjusted to within the specified range mentioned above, the base layer 51 can more reliably maintain appropriate flexibility and strength.

[0064] Furthermore, if the tensile strengths of TD and MD are adjusted to within the specified range described above, the desired strength can be obtained even more reliably as the base layer 51.

[0065] By using a polyamide film with the above-mentioned properties for the base layer 51, an exterior material 1 with good moldability and sufficient puncture resistance can be obtained.

[0066] Furthermore, if the number-average molecular weight of the nylon used as the base layer 51 is 15,000 or more, the base layer 51 becomes less prone to tearing, and if the molecular weight is 30,000 or less, the flexibility of the base layer 51 can be maintained, making it less prone to cracking.

[0067] In this embodiment, it is preferable to adjust the relative viscosity of the polyamide film as the base layer 51 to 2.9 to 3.1. That is, when the relative viscosity is adjusted to the above specific range, strength and flexibility can be more effectively imparted to the base layer 51, and an exterior material 1 with good moldability and high puncture resistance can be reliably obtained.

[0068] 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.

[0069] In this embodiment, the thickness of the base layer 51 (polyamide film) is preferably adjusted to 9 μm to 50 μm, and more preferably to 12 μm to 30 μm.

[0070] Here, the distribution of the hot water shrinkage rate in the polyamide film of this embodiment will be explained. First, in a square polyamide film, the hot water shrinkage rates at three points along both sides and the center line in the vertical direction (MD) are defined as the fixed-point hot water shrinkage rates at three points along MD, and the hot water shrinkage rates at three points along both sides and the center line in the horizontal direction (TD) are defined as the fixed-point hot water shrinkage rates at three points along TD. It is preferable to use a film in which the difference between the maximum fixed-point hot water shrinkage rate and the minimum fixed-point hot water shrinkage rate among the total of six fixed-point hot water shrinkage rates (three fixed-point hot water absorption rates along MD and three fixed-point hot water absorption rates along TD) is adjusted to 2.5 or less.

[0071] The average of the three fixed-point hydrothermal contraction rates for MD corresponds to the average hydrothermal contraction rate for MD, and the average of the three hydrothermal contraction rates for TD corresponds to the average hydrothermal contraction rate for TD.

[0072] In Figure 4, the three regions indicated by the dashed lines are all square regions of the polyamide film (base layer 51) of the same size. When these square regions satisfy the above-mentioned distribution conditions for the thermal shrinkage rate, the uneven distribution of flexibility is suppressed throughout the entire base layer 51. As a result, even if external stress is applied, it is distributed throughout the entire base layer 51, making it less likely to tear and thus reliably improving its strength.

[0073] In this embodiment, the base layer 51 is formed from a polyamide film, but as previously described, other layers may be laminated on the base layer 51.

[0074] Furthermore, it is preferable to use a resin for the base layer 51 that has a melting point at least 10°C higher than all the resins constituting the sealant layer 53, and more preferably a resin that has a melting point at least 20°C higher. In other words, when this configuration is adopted, adverse effects of heat on the base layer 51 can be avoided when heat-sealing the sealant layer 53.

[0075] In this embodiment, the first adhesive layer (colored adhesive layer) 61 is responsible for bonding the metal foil layer 52 and the base material layer 61, and is a layer that imparts color (including achromatic) to the outer surface of the exterior material 1. It is composed of a colored adhesive composition containing a colored pigment and a specific adhesive (adhesive component).

[0076] Suitable coloring pigments include azo pigments, phthalocyanine pigments, condensed polycyclic pigments, and inorganic pigments. Carbon black is recommended as the black pigment.

[0077] It is preferable to use coloring pigments with an average particle size of 0.1 μm to 5 μm, and particularly preferable average particle size of 0.5 to 2.5 μm.

[0078] When dispersing pigments, it is preferable to use a pigment disperser, and pigment dispersants such as surfactants can also be used during pigment dispersion.

[0079] The adhesive component of the first adhesive layer 61 is composed of an adhesive containing a two-component curable polyester urethane resin, which consists of a polyester resin as the main component and a polyfunctional isocyanate compound as the curing agent. In the present invention, by defining the molecular weight of the polyester resin, which is the main component of the two-component curable polyester urethane resin, and defining the type of polyfunctional isocyanate compound, the adhesive strength and moldability can be improved, and interlayer delamination can be suppressed when deep molding is performed during the molding of the exterior material 1.

[0080] The polyester resin used as the main component is a copolymer derived from dicarboxylic acid and dialcohol, and preferred materials and compositions are as follows.

[0081] It is preferable to use both aliphatic dicarboxylic acids and aromatic dicarboxylic acids as the dicarboxylic acid. Furthermore, the odd or even number of methylene groups in the methylene chain of an aliphatic dicarboxylic acid is a factor that affects the crystallinity of the resin, and since dicarboxylic acids with an even number of methylene groups produce hard resins with high crystallinity, it is preferable to use aliphatic dicarboxylic acids with an even number of methylene groups. Examples of aliphatic dicarboxylic acids with an even number of methylene groups include succinic acid (2 methylene groups), adipic acid (4 methylene groups), suberic acid (6 methylene groups), and sebacic acid (8 methylene groups).

[0082] Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, and phthalic anhydride.

[0083] 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 moldability is produced, enabling molding into cases with high side walls and suppressing delamination between the metal foil layer 52 and the base material layer 51, resulting in an exterior material (packaging material) 1.

[0084] Here, if the aromatic dicarboxylic acid content is less than 40 mol%, the film properties deteriorate and cohesive delamination becomes more likely, which may lead to interlayer delamination.

[0085] On the other hand, when the aromatic dicarboxylic acid content exceeds 80 mol%, the resin tends to harden and its adhesion performance decreases. A particularly preferable aromatic dicarboxylic acid content is 50 mol% to 70 mol%.

[0086] Examples of dialcohols in the polyester resin used as the main component of the adhesive 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.

[0087] In the above-mentioned polyester resin, it is preferable to specify the number average molecular weight (Mn) to be in the range of 8,000 to 25,000 and the weight average molecular weight (Mw) to be in the range of 15,000 to 50,000, and further, the ratio of these (Mw / Mn) to be 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, appropriate coating film strength and heat resistance can be obtained, and when the number average molecular weight (Mn) is 25,000 or less and the weight average molecular weight (Mw) is 50,000 or less, appropriate coating film elongation can be obtained without becoming too hard.

[0088] Furthermore, a ratio (Mw / Mn) of 1.3 to 2.5 results in an appropriate molecular weight distribution, allowing for a balance between adhesive application suitability (wide distribution) and performance (narrow distribution).

[0089] In the above polyester resin, the most preferred number-average molecular weight (Mn) is 10,000 to 23,000, the most preferred weight-average molecular weight (Mw) is 20,000 to 40,000, and the most preferred (Mw / Mn) is 1.5 to 2.3.

[0090] Furthermore, the molecular weight of the above polyester resin can be adjusted by extending the chain with a polyfunctional isocyanate. That is, by linking the polyester component in the main agent with NCO, a polymer with hydroxyl groups at the ends is produced, and the molecular weight of the polyester resin can be adjusted by adjusting the equivalent ratio of the isocyanate group to the hydroxyl group of the polyester. In the present invention, it is preferable to use a polymer linked so that these equivalent ratios (OH / NCO) are 1.01 to 10. Another method for adjusting the molecular weight is to change the reaction conditions of the condensation polymerization reaction between the dicarboxylic acid and the dialcohol (adjustment of the molar ratio of the dicarboxylic acid and the dialcohol).

[0091] Furthermore, in this embodiment, epoxy resins or acrylic resins may be added as additives to the main component of the adhesive.

[0092] As the polyfunctional isocyanate compound that serves as the curing agent for the adhesive component, various isocyanate compounds of the aromatic, aliphatic, and alicyclic types can be used. Specifically, examples include polyfunctional isocyanate modified products derived from one or more types of diisocyanates such as aliphatic hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and aromatic tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI).

[0093] Examples of modification methods include adducts with water, glycerin, trimethylolpropane, and other polyfunctional isocyanate modified products obtained by polymerization reactions such as isocyanuration, carbodiimide, and polymerization. One or more of these can be used in combination. However, in order to increase the adhesive strength after curing and obtain an effect that prevents peeling of the substrate layer 51, it is preferable to contain 50 mol% or more of aromatic isocyanate compounds. A more preferable content of aromatic isocyanate compounds is 70 mol% or more.

[0094] In the above-mentioned two-component curable polyester urethane resin adhesive component, the mixing ratio of the main agent and the curing agent is preferably 2 to 25 moles of isocyanate functional groups (-NCO) per 1 mole of polyol hydroxyl groups (-OH). If the molar ratio (-NCO) / (-OH) is less than 2 and the amount of isocyanate functional groups (-NCO) is low, a sufficient curing reaction may not occur, and appropriate coating film strength and heat resistance may not be obtained. On the other hand, if the (-NCO) / (-OH) ratio exceeds 25 and the amount of isocyanate functional groups (-NCO) is high, the reaction with functional groups other than polyol may proceed too much, causing the coating film to become too hard and preventing the proper elongation from being obtained. A particularly preferred molar ratio (-NCO) / (-OH) of polyol hydroxyl groups to isocyanate functional groups is 5 to 20.

[0095] The above two-component curable polyester urethane resin preferably has the following physical properties in the cured film after the reaction.

[0096] To ensure good moldability and interlayer bonding strength of the sealing packaging material, the above-mentioned cured film preferably has a Young's modulus of 70 MPa to 400 MPa as determined by a tensile test (JIS K7162). A particularly preferred Young's modulus is 100 MPa to 300 MPa.

[0097] Furthermore, it is preferable that the breaking strength is 20 MPa to 70 MPa and the elongation at break is 50% to 400%. Particularly preferable is a breaking strength of 30 MPa to 50 MPa and a particularly preferable elongation at break of 100% to 300%.

[0098] Furthermore, it is preferable that the tensile stress-strain curve (S-S curve) does not show a strength decrease before fracture. FIG. 5 shows three patterns of the S-S curve. For the tensile stress, in Pattern A the amount of strain is small and in Pattern B the amount of strain is large, but in both cases the amount of strain increases with an increase in the tensile stress, and no strength decrease before fracture is observed. On the other hand, in Pattern C, the tensile stress decreases during the process of increasing the amount of strain, indicating a strength decrease before fracture. In the present invention, it is preferable that the cured film of the two-component curable adhesive does not show a strength decrease in the S-S curve. More preferably, it is preferable that there is no inflection point where the strength changes abruptly in the S-S curve.

[0099] The adhesive containing the above two-component curable polyester urethane resin is prepared by carrying out a condensation polymerization of a dicarboxylic acid and a dialcohol which are raw materials of the polyester resin, and if necessary, further chain-extending with an isocyanate which is more functional, and mixing various additives such as a solvent, a urethanization reaction catalyst, a coupling agent or an epoxy resin for improving the adhesive strength, an antifoaming agent, a leveling agent, an ultraviolet absorber, an antioxidant, etc. to obtain a fluid polyester resin solution, and then blending a polyfunctional isocyanate compound which is a curing agent or further a solvent thereto to prepare a low-viscosity fluid.

[0100] The preferable conditions (1) and (2) of the components in the above coloring adhesive composition constituting the first adhesive layer 61 are as follows. The content rates described below are the ratios of solid components not including the solvent.

[0101] (1) The coating amount (existing amount) of the coloring adhesive composition as the first adhesive layer 61 is 5 g / m 2 ~10 g / m 2 .

[0102] (2) The first adhesive layer 61 contains 0.25 g / m 2 ~0.49 g / m 2 of a coloring pigment.

[0103] Based on the above (1) and (2), the content rate of the coloring pigment contained in the first adhesive layer 61 is preferably in the range of 2 mass% or more and less than 5 mass%.

[0104] If the coloring pigment content exceeds 5% by mass, the visual effect will not be achieved, and peeling may occur more easily during hot water immersion tests. If the coloring pigment content is less than 2% by mass, the shielding effect will be poor, the visual effect will be insufficient, and there may be problems with the appearance.

[0105] Therefore, the range of the color pigment content in the first adhesive layer of this application is 2% by mass or more and less than 5% by mass. A more preferable color pigment content is 2.5% by mass or more and 4.5% by mass or less.

[0106] This coloring pigment has a content of 0.25 g / m² 2 If the amount is less than 0.49 g / m², the opacity and visual effect will be insufficient, which may be problematic in terms of design and is undesirable. Also, the amount of coloring pigment is less than 0.49 g / m². 2 Beyond this point, the improvement in visual effect almost disappears, and in fact, delamination may become more likely to occur in the hot water immersion test described later. Therefore, the effective content range of the coloring pigment contained in the first adhesive layer 61 of this application is 0.25 g / m². 2 ~0.49g / m 2 The range is such that a more preferable color pigment content is 0.25 g / m². 2 ~0.45g / m 2 It is within the range.

[0107] The above range of color pigment content (concentration) is a mandatory condition when conducting the 45°C hot water immersion test, which is the most stringent environmental test after the battery packaging material is molded, and the color pigment content is 0.49 g / m². 2 If the temperature exceeds a certain point, the first adhesive layer 61 becomes hard and brittle, reducing its adhesive strength to the metal foil layer 52, which can cause the base material layer (heat-resistant resin layer) 51 to peel off during the hot water immersion test.

[0108] Furthermore, in a general environmental test after the battery packaging material was molded (high temperature and high humidity storage test at 70°C × 90%RH), the color pigment content was 0.49 g / m². 2 If the following conditions are met, the base material layer (heat-resistant resin layer) 51 will not peel off during the storage test, and the product can be used.

[0109] The color pigment content is 0.49 g / m 2 If the temperature exceeds a certain level, the likelihood of delamination of the substrate layer 51 during the high-temperature, high-humidity storage test increases, which is undesirable.

[0110] The amount of the first adhesive layer (colored adhesive composition) 61 applied is 5 g / m². 2 If the amount is less than the specified value, the amount of coloring pigment will be low, which, as mentioned above, will reduce the effect of concealing the metal foil layer, and may also cause the metallic luster to become visible, potentially diminishing the sense of weight and substance.

[0111] Furthermore, the application amount of the first adhesive layer 61 is 10 g / m². 2 If the amount exceeds this, the processability deteriorates significantly, leading to increased costs. The preferred application amount of the colored adhesive composition is 6 g / m². 2 ~10g / m 2 That is the case.

[0112] The colored adhesive composition is prepared by blending a colored pigment and an adhesive (including a solvent and various additives) containing a two-component curable polyester urethane resin prepared by the method described above in a predetermined ratio.

[0113] Furthermore, while the method of bonding the metal foil layer 52 and the substrate layer 51 is not limited, a method called dry lamination is recommended. Specifically, the prepared colored adhesive composition is applied to the upper surface (outer surface) of the metal foil layer 52, the lower surface (inner surface) of the substrate layer 51, or both of these surfaces, the solvent is evaporated to form a dry film, and then the metal foil layer 52 and the substrate layer 51 are bonded together. After that, the resin is further cured according to the curing conditions of the two-component curable polyester urethane resin. As a result, the metal foil layer 52 and the substrate layer 51 are joined via the first adhesive layer 61. Examples of application methods for the colored adhesive composition include gravure coating, reverse roll coating, and lip roll coating.

[0114] In this embodiment, the metal foil layer 52 plays a role as a gas barrier that prevents the intrusion of oxygen and moisture.

[0115] Examples of metal foil layers 52 include aluminum foil, copper foil, and stainless steel foil, with aluminum foil being particularly suitable. In particular, when using Al-Fe alloy foil containing 0.7% to 1.7% by mass of Fe, excellent strength and ductility can be obtained, along with good formability.

[0116] 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 prevents the occurrence of pinholes during rolling when manufacturing the metal foil, and a thickness of 100 μm or less reduces stress during stretching and deep drawing, thereby improving formability.

[0117] In the exterior packaging material of 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.

[0118] Chemical treatments include chromate treatment and non-chromium type chemical treatments using zirconium compounds.

[0119] For example, in the case of chromate treatment, an aqueous solution of one of the following mixtures 1) to 3) is applied to the surface of the degreased metal foil and then dried.

[0120] 1) A mixture of phosphoric acid, chromic acid, and at least one of a metal salt of fluoride and a nonmetal salt of fluoride. 2) A mixture of phosphoric acid, one of acrylic resins, chitosan derivative resins, and phenolic resins, and at least one of chromic acid and chromium(III) salts. 3) A mixture of phosphoric acid, one of acrylic resins, chitosan derivative resins, or phenolic resins, at least one of chromic acid and chromium(III) salts, and at least one of a metal salt of fluoride and a nonmetal salt of fluoride. The amount of chromium deposited on the chemical conversion coating 63 is 0.1 mg / m². 2 ~50mg / m 2It is best to set it to 2 mg / m², more preferably 2 mg / m². 2 ~20mg / m 2 It's best to set it to that.

[0121] Furthermore, the chemical conversion coating 63 may also be applied to either one of the surfaces of the metal foil layer 52.

[0122] The sealant layer (heat-fusible 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 plays a role in providing heat-sealability to the exterior material 1.

[0123] The sealant layer 53 is preferably an unstretched heat-sealable resin film layer. This unstretched heat-sealable resin film is preferably composed of an unstretched film made of at least one heat-sealable resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers, in terms of chemical resistance and heat sealability.

[0124] 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. In other words, by setting this thickness to 20 μm or more, the occurrence of pinholes can be sufficiently prevented, and by setting it to 80 μm or less, the amount of resin used can be reduced, thereby reducing costs.

[0125] The sealant layer 53 may be a single layer or a multi-layer layer. In the case of a multi-layer layer, a three-layer film can be exemplified by laminating random polypropylene films on both sides of a block polypropylene film.

[0126] Examples of the second adhesive layer (uncolored adhesive layer) 62 include adhesive layers formed from polyurethane adhesives, acrylic adhesives, epoxy adhesives, polyolefin adhesives, elastomer adhesives, fluorine-based adhesives, acid-modified polypropylene adhesives, and the like.

[0127] In particular, it is preferable to use acrylic adhesives or polyolefin adhesives, in which case the electrolyte resistance and water vapor barrier properties of the exterior material 1 can be improved.

[0128] The method of bonding the metal foil layer 52 and the sealant layer 53 is not limited, but a dry lamination method is an example in which the adhesive constituting the second adhesive layer 62 is applied and dried before bonding, similar to the bonding of the metal foil layer 52 and the substrate layer 51 described above.

[0129] The matte coat layer 50 is laminated on the outer surface of the base material layer 51 and is a layer that provides good slipperiness to the surface of the exterior material 1, thereby improving moldability.

[0130] The matte coat layer 50 contains a binder resin and solid fine particles (wax, resin beads, inorganic fine particles). The average particle size of the wax is 5 μm to 20 μm, the average particle size of the resin beads is 1 μm to 10 μm, and the average particle size of the inorganic fine particles is 1 μm to 10 μm. Each solid fine particle is contained in an amount of 1% to 20% by mass, and it is preferable that the total content of solid fine particles such as wax, resin beads, and inorganic fine particles in the matte coat layer 50 is 30% by mass or more and 50% by mass or less.

[0131] The binder resin described above is preferably a resin comprising a main polyol and a curing agent polyfunctional isocyanate. Examples include at least one selected from acrylic polyol resin, urethane polyol resin, polyolefin polyol resin, polyester polyol resin, phenoxy resin, copolymer of tetrafluoroolefin and vinyl carboxylate, and copolymer of tetrafluoroolefin and alkyl vinyl ether.

[0132] As a binder resin, it is preferable to use a tetrafluoroethylene-based fluororesin due to its excellent heat resistance and chemical resistance.

[0133] Examples of the above-mentioned waxes include at least one selected from polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, and the like.

[0134] For this wax, it is preferable to use one with an average particle size of 5 μm to 20 μm, and more preferably one with a particle size of 6 μm to 18 μm. The wax content is preferably set to 1% to 10% by mass, and more preferably to 2% to 8% by mass.

[0135] Furthermore, the resin beads mentioned above include at least one selected from acrylic resin beads, urethane resin beads, polyethylene resin beads, polystyrene resin beads, silicone resin beads, fluororesin beads, etc. The resin beads should preferably have an average particle size of 1 μm to 10 μm, and more preferably 2 μm to 8 μm. The resin bead content should preferably be set to 1% to 20% by mass, and more preferably 3% to 17% by mass.

[0136] Examples of the inorganic fine particles mentioned above include at least one selected from silica, alumina, kaolin, calcium oxide, calcium carbonate, calcium sulfate, barium sulfate, calcium silicate, etc. It is preferable to use inorganic fine particles with an average particle size of 1 μm to 10 μm, and more preferably 1 μm to 5 μm. Furthermore, the inorganic fine particle content is preferably set to 20% to 40% by mass, and more preferably 25% to 35% by mass.

[0137] The matte coat layer 50 is formed by applying a matte coat composition containing the above-mentioned solid fine particles and heat-resistant resin to the surface of the substrate layer 51 and curing it.

[0138] The matte coating layer 50 is preferably set to a thickness of 0.5 μm to 5 μm, and more preferably to 1 μm to 3 μm. In other words, if the matte coating layer 50 is too thin, the effect of improving slipperiness will be reduced, and if it is too thick, it will increase costs, which is undesirable.

[0139] The timing of the process for forming the matte coat layer 50 is not limited, but it is preferable to perform it following the process of laminating the base layer 51 to the metal foil layer 52 via the first adhesive layer 61. Alternatively, the matte coat layer 50 may be formed by laminating an unoriented polypropylene (CPP) film to the base layer 51.

[0140] In the above embodiments, the use of the sealing packaging material of the present invention as an exterior material for energy storage devices such as batteries was described as an example. However, the present invention is not limited to this, and the packaging material of the present invention can also be used as a packaging material for sealing and sealing contents such as food and pharmaceuticals.

[0141] Furthermore, although the above embodiment describes the case in which a sheet-like outer packaging material 1 is used as the cover member 3, the present invention is not limited to this, and the cover member 3 may also be molded. For example, the cover member may be made of a molded product with a hat-shaped cross-section in which the central part is formed to be concave upward, and the outer edge of the hat-shaped cover member may be joined and integrated so as to cover the tray member as described above from above. Moreover, in the present invention, a casing may be formed by overlapping two unmolded sheet-like outer packaging materials 1 so as to sandwich the energy storage device body and heat-sealing their outer edges.

[0142] Furthermore, while the above embodiment describes an example where two outer packaging materials (outer laminate materials) are used to form the casing, the invention is not limited to this. In the present invention, the number of outer packaging materials used to form the casing is not limited; it may be one, three or more, or any other number.

[0143] Furthermore, it goes without saying that the packaging material of the present invention does not necessarily require the inclusion of preferred requirements such as the matte coat layer 50 and the chemical conversion coating layer 63. [Examples]

[0144] Next, examples illustrating the gist of the present invention and comparative examples for deriving its effects will be described. Needless to say, the present invention is not limited to the following examples.

[0145] In Examples 1-8 and Comparative Examples 1-9 below, the laminated outer packaging material (packaging material) shown in Figure 3 was fabricated. As shown in Table 1, the only differences between the Examples and Comparative Examples are the polyamide film used as the base layer and the first adhesive layer (coloring adhesive layer); all other components are the same.

[0146] [Table 1]

[0147] <Example 1> As the metal foil layer, an aluminum foil conforming to JIS H4160 A8079 with a thickness of 35 μm was prepared. Furthermore, a chemical conversion treatment solution consisting of polyacrylic acid, trivalent chromium compound, water, and alcohol was applied to both sides of this aluminum foil, and dried at 150°C to form a chemical conversion film. The amount of chromium deposited by this chemical conversion film was 10 mg / m². 2 That is the case.

[0148] A biaxially oriented nylon (ONY) film with a thickness of 15-25 μm was prepared as the base layer. The bonding surface (bottom surface) of this film with the first adhesive layer was subjected to corona treatment.

[0149] The biaxially oriented nylon film used as the base layer has a TD hot water shrinkage rate of 2.7%, an MD hot water shrinkage rate of 2.0%, a difference in hot water shrinkage rates between TD and MD (TD-MD) of 0.7%, a TD modulus of elasticity of 1.7 GPa, an MD modulus of elasticity of 2.7 GPa, a TD breaking strength of 361 MPa, an MD breaking strength of 280 MPa, and a polyamide number-average molecular weight of 25,000.

[0150] The colored adhesive composition constituting the first adhesive layer was prepared using a two-component curable polyester urethane resin as the adhesive component and carbon black as the coloring pigment by the following method.

[0151] First, a polyester resin (polyester polyol), which is the main component of the two-component curable polyester urethane resin, was prepared. This main component was prepared by melting 30 moles of neopentyl glycol, 30 moles of ethylene glycol, and 40 moles of 1,6-hexanediol at 80°C. While stirring, 30 moles of adipic acid (methylene 4), an aliphatic dicarboxylic acid, and 70 moles of isophthalic acid, an aromatic dicarboxylic acid, were added and subjected to a condensation polymerization reaction at 210°C for 20 hours to obtain 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 of these (Mw / Mn) of 1.7. Furthermore, 60 parts by mass of ethyl acetate were added to 40 parts by mass of this polyester polyol to prepare a polyester polyol resin solution in a flow field. The hydroxyl value was 2.2 mgKOH / g (solution value).

[0152] Next, 100 parts by mass of the above polyester polyol resin solution and 64.4 parts by mass of ethyl acetate were mixed with the required amount of carbon black with an average particle size of 1.0 μm, and the carbon black pigment was dispersed using a pigment disperser to obtain a main component containing colored pigment. Then, to 100 parts by mass of the above main component containing colored pigment, 7.1 parts by mass of an adduct (NCO% 13.0%, solids content 75%) of tolylene diisocyanate (TDI) (aromatic), which is an aromatic isocyanate compound, and trimethylolpropane was mixed as a curing agent, and 34.1 parts by mass of ethyl acetate was added and the mixture was thoroughly stirred to obtain a colored adhesive composition. In this colored adhesive composition, the molar ratio (-NCO) / (-OH) of isocyanate functional groups (-NCO) to polyester polyol hydroxyl groups (-OH) is 10. As shown in Table 1, the pigment concentration (pigment content) in this colored adhesive composition is 3.9% by mass.

[0153] The cured film of the above-mentioned two-component curable polyester urethane resin adhesive, specifically a cured film with a composition obtained by removing the coloring pigment from the composition of the first adhesive layer, was prepared and its physical properties were evaluated. Specifically, the two-component curable polyester urethane resin adhesive was applied to an untreated, non-adhesive PP film to a dry thickness of 50 μm. After drying the solvent, it 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 wide pieces to be used as test specimens.

[0154] The prepared specimens were subjected to tensile tests under conditions of a gauge length of 50 mm and a tensile speed of 200 mm / min. Young's modulus, breaking strength, and elongation at break were measured, and the results showed a Young's modulus of 140 MPa, a breaking strength of 48 MPa, and an elongation at break of 217%. Furthermore, the tensile strength curve (SS) for this tensile test was determined, and its pattern was pattern A as shown in Figure 5.

[0155] Meanwhile, 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.

[0156] Furthermore, as a matte coat layer, a composition for the matte coat layer was prepared by mixing 70 parts by mass of fluoroethylene vinyl ester as a heat-resistant resin, 10 parts by mass of barium sulfate and 10 parts by mass of powdered silica as inorganic fine particles, 5 parts by mass of polytetrafluoroethylene wax as a wax, and 5 parts by mass of polyethylene resin beads as resin beads.

[0157] A predetermined amount of the above-mentioned colored adhesive composition was applied to one side (outer surface) of the aluminum foil for the metal foil layer, which had a chemical conversion coating formed on both sides, and dried to form a first adhesive layer. The amount of colored adhesive composition applied, the number average molecular weight Mn, the weight average molecular weight Mw, Mw / Mn, and the carbon black content (amount applied) are as shown in Table 1. Then, the film for the base layer was laminated onto the first adhesive layer to form the base layer.

[0158] Next, the polyacrylic adhesive, serving as the second adhesive layer, was applied to the other side (bottom surface) of the metal foil layer, and the polypropylene film, serving as the sealant layer, was laminated to its outer surface.

[0159] Furthermore, the above-mentioned matte coating layer composition was applied to the outer surface of the substrate layer so that its thickness after drying was 2 μm.

[0160] By leaving the laminated structure in a 40°C environment for 5 days to age, the material for Example 1 (exterior material for energy storage devices) was obtained.

[0161] <Examples 2-8 and Comparative Examples 1-9> As shown in Table 1, the thickness, hydrothermal shrinkage rate, elastic modulus, breaking strength, and number-average molecular weight were adjusted in the base layer, and the pigment concentration (carbon black concentration), amount of colored adhesive composition applied, amount of pigment applied (content), number-average molecular weight Mn, weight-average molecular weight Mw, and Mw / Mn were adjusted in the first adhesive layer. Otherwise, the packaging materials for Examples 2-8 and Comparative Examples 1-9 were obtained in the same manner as in Example 1.

[0162] However, in the packaging material sample of Example 6, a layer of easy-adhesion treatment agent (0.2 g / m²) made of urethane resin was applied to the corona-treated surface of the polyamide film (base layer). 2 ) was established.

[0163] <Evaluation Test> (1) Evaluation of concealment (shielding) properties The opacity of the metal foil layer was confirmed by visually inspecting each packaging material in the examples and comparative examples from the base layer side (outer surface side). Materials with good opacity were rated "○", and those without opacity were rated "×". The evaluation results obtained are shown in Table 2.

[0164] [Table 2]

[0165] (2) Evaluation of moldability We prepared a press machine manufactured by Amada Corporation, equipped with a punch mold measuring 33mm x 54mm, with punch corner radius of 2mm, punch shoulder radius of 1.3mm, and die shoulder radius of 1mm.

[0166] Then, each packaging material from the examples and comparative examples was sampled into a 100mm x 125mm blank shape, and molded product samples were prepared by deep drawing molding using the press machine described above.

[0167] The presence or absence of pinholes and cracks in the corners of each molded product obtained by this deep drawing process was checked, and the "maximum molding depth (mm)" at which no pinholes or cracks occurred was determined and evaluated based on the following criteria. For evaluation, the presence or absence of cracks and pinholes was checked using the light transmission method in a dark room. Of the evaluation criteria described below, "◎" and "○" indicate a pass, and "×" indicates a fail. The results are shown in Table 2.

[0168] ◎: No cracks or pinholes in molded depth of 6mm or more. ○: Molding depth of 5mm or more and less than 6mm, with no cracks or pinholes. ×: Cracks or pinholes present in molded depths of less than 5mm. (3) Evaluation of peeling of the substrate layer (3-1) Peel strength Each packaging material from the examples and comparative examples was sampled to a predetermined size, and deep drawing was performed on each sample in the same manner as described above to produce a molded case (an inverted tray-like member) 2 having a recessed portion (protrusion) 21 measuring 33 mm × 54 mm × 4.5 mm, and a flat flange portion 22 on the outer circumference of the protrusion, as shown in Figure 6. Furthermore, the top wall (top surface) 25 of the protrusion of the molded product 2 was deformed into a concave shape by crushing it, and then the crushed molded product 2 was immersed in 40°C hot water for one week. After immersion for one week, the molded product was removed from the water, and the laminate strength (ONY / Al laminate strength [N / 15 mm]) between the base material layer and the metal foil layer was measured immediately after removal, while the molded product still had water on it. The results are shown in Table 2.

[0169] (3-2) Presence or absence of peeling Similar to the "(3-1) Peel Strength" described above, a molded case 2 was prepared as a molded product. Furthermore, the top wall (top surface) 25 of the convex part of the molded product 2 was deformed into a concave shape by crushing it, and then the following high temperature and high humidity test and hot water immersion test were performed, and the presence or absence of peeling of the base material layer after the test was visually observed.

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

[0171] In both tests, 30 molded articles 2 were visually inspected for each example and each comparative example, and the results were judged based on the number of molded articles 2 in which the base layer had peeled off from the metal foil layer, according to the following criteria. Of the following criteria, "◎", "○", "△", and "×", "◎", "○", and "△" indicate a pass, and "×" indicates a fail. The results are shown in Table 2.

[0172] ◎: 0 out of 30 items were detached. ○: Out of 30, 1 or 2 were detached. △: 3 to 5 out of 30 pieces have peeled off. ×: 6 to 30 out of 30 pieces were detached. (4) Evaluation of processability When preparing each packaging material for the examples and comparative examples, the drying time after applying the first adhesive layer (colored adhesive composition) was measured. In this process, the drying time of Example 5 was used as the reference time, and samples with a drying time 15% or more slower than the reference time were evaluated as "×: Fail," while all others were evaluated as "〇: Pass." The results are shown in Table 2.

[0173] (5) Measurement of puncture strength (evaluation of puncture resistance) The puncture resistance was measured in accordance with JIS (Japanese Industrial Standards) Z1707:2019. The puncture resistance test was performed according to the following procedure (5-1) to (5-3).

[0174] (5-1) The test specimens obtained from the packaging materials of each example and comparative example are fixed with a jig, and a semicircular needle with a diameter of 1.0 mm and a tip radius of 0.5 mm is inserted at a test speed of 50 ± 5 mm / min, and the maximum force (N) until the needle penetrates is measured.

[0175] (5-2) The number of test specimens shall be five or more for each example and each comparative example, and shall be taken in an average manner across the entire width of the test specimen.

[0176] (5-3) If the test results depend on whether the film penetrates from any side, the test shall be performed on each side. The measured value (reported value) shall be rounded to one decimal place. The results are shown in Table 2.

[0177] The obtained measurements were evaluated according to the following criteria. Of the judgment criteria, "◎", "○", "△", and "×", "◎", "○", and "△" were judged as passing, and "×" as failing. The results are shown in Table 2.

[0178] ◎: Measured value between 26N and 30N ○: Measured value is between 24N and less than 26N △: Measured value is between 22N and less than 24N ×: Measured value less than 22N <Overall Rating> As is clear from the above evaluation results, the packaging material (outer packaging material) of the example related to the present invention received excellent evaluations in all aspects, including shielding properties, moldability, peel resistance, processability, and puncture resistance. In contrast, the packaging material of the comparative example, which deviates from the gist of the present invention, was inferior to the packaging material of the example in any of these evaluations.

[0179] In particular, the following points are clear from "(3) Evaluation regarding delamination of the base material layer." That is, even if a base material layer (polyamide film) with a hot water shrinkage rate TD / MD ≤ 1.5 is used in the packaging material, residual stress remains in the base material layer after molding, and in areas where molding distortion becomes large depending on the molding dimensions (MD direction or TD direction), delamination of the base material layer may occur in high temperature, high humidity, and hot water immersion environments. In contrast, in the packaging material of the example, the amount of colored adhesive layer applied is 5 g / m 2 ~10g / m 2 The amount of pigment applied is 0.25 g / m². 2 ~0.49g / m 2 Because it is adjusted within a certain range, it is possible to prevent the occurrence of coating defects due to aggregated pigment particles and surface roughness on the coating surface, and to maintain good adhesive strength between the base layer, colored adhesive layer, and metal foil layer. In other words, it is clear that the packaging material related to the present invention is excellent in both moldability and interlayer adhesion. [Industrial applicability]

[0180] The packaging material of this invention can be suitably used as an outer casing material for batteries (energy storage devices) such as laptop computers, mobile phones, in-vehicle (mobile) or stationary secondary batteries (lithium-ion secondary batteries). [Explanation of Symbols]

[0181] 1: Exterior material (packaging material) 10: Energy storage device unit 2: Tray components (packaging materials, outer packaging materials, packaging containers) 3: Cover components (packaging materials, outer packaging materials) 50: Matte Coat Layer 51: Base material layer 52: Metal foil layer 53: Sealant layer 61: First adhesive layer (colored adhesive layer) 63: Chemical conversion coating MD: Orthogonal direction TD: Molding direction

Claims

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, wherein a colored adhesive layer is provided between the metal foil layer and the base layer, the base material layer has a hot water shrinkage rate in both TD and MD of 2.0% to 5.0%; The base material layer has a difference between a hot water shrinkage rate in the TD and a hot water shrinkage rate in the MD of 1.5% or less, the base material layer has a TD modulus of elasticity and a MD modulus of elasticity of 1.5 GPa to 3 GPa; the colored adhesive layer is made of a colored adhesive composition containing a color pigment and an adhesive; The colored adhesive layer has a thickness of 5 g / m ２ ~10g / m ２ The colored adhesive composition of The colored adhesive layer has a thickness of 0.25 g / m ２ ~0.49g / m ２ A packaging material characterized by containing the color pigment described above.

2. the colored adhesive layer contains a two-component curing polyester urethane resin containing 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, a weight average molecular weight (Mw) of 15,000 to 50,000, and a ratio thereof (Mw / Mn) of 1.3 to 2.5; The polyfunctional isocyanate compound as a curing agent contains 50 mol% or more of an aromatic isocyanate, 2. The packaging material according to claim 1, wherein the substrate layer is made of a polyamide film having a number average molecular weight of 15,000 to 30,000.

3. 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, 3. The packaging material according to claim 2, wherein the dicarboxylic acid comprises 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 the aliphatic dicarboxylic acid and the aromatic dicarboxylic acid is 40 mol % to 80 mol %.

4. 4. The packaging material according to claim 2, wherein the cured film of the two-component curing polyester urethane resin has a Young's modulus of 70 MPa to 400 MPa in a tensile test in accordance with JIS K7162.

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

6. The packaging material according to any one of claims 1 to 3, wherein a matte coating layer is provided on the outer surface of the base material layer.

7. The packaging material according to any one of claims 1 to 3, wherein the base material layer has at least one of a TD breaking strength and an MD breaking strength of 320 MPa or more.

8. A packaging container, comprising the packaging material according to any one of claims 1 to 3, and a formed portion formed by deep drawing or stretch forming.

9. An exterior packaging material for an electricity storage device, comprising the packaging material according to any one of claims 1 to 3.

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

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