JP2022182409A - Resin film for terminal, and power storage device using the same - Google Patents

Abstract

To provide a resin film for a terminal which has excellent adhesion to a terminal under a room temperature environment and a high temperature environment after having been brought into contact with an electrolytic solution even when thickened.SOLUTION: A resin film for a terminal is arranged so as to cover a partial outer peripheral surface of a metal terminal electrically connected to a power storage device body constituting a power storage device, wherein the resin film for the terminal has a following A layer and a lamination structure, and the lamination structure is formed by laminating a following B layer, a following C layer and the following B layer in this order. A layer: layer formed using a resin composition containing an acid-modified polyolefin resin having a melting point of 100°C or higher and 170°C or lower. B layer: layer formed using a resin composition containing a first polyolefin resin having a melting point of 100°C or higher and lower than 160°C, and a second polyolefin resin having a melting point of 160°C or higher and 170°C or less. C layer: layer formed using a resin composition containing a polyolefin resin having a melting point of 160°C or higher and 170°C or lower.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a terminal resin film and an electric storage device using the same.

In recent years, there have been increasing demands for the miniaturization of mobile devices and the effective use of naturally generated energy, and research and development of lithium-ion secondary batteries (a type of electricity storage device) with higher voltage and higher energy density is being conducted. there is

Conventionally, many metal cans have been used as packaging materials for lithium ion secondary batteries. BACKGROUND ART Packaging materials in which a laminated body obtained by laminating a metal layer (for example, aluminum foil) and a resin film in the form of a bag have come to be used in many cases.

A laminate-type lithium ion secondary battery in which the battery body is housed and sealed inside the packaging material is provided with a current extraction terminal called a tab. The tab is connected to the negative electrode or positive electrode of the battery body and covers the metal terminal (sometimes called "tab lead") extending outside the packaging material (exterior material) and the outer peripheral surface of a part of the metal terminal. and a terminal resin film (sometimes called “tab sealant”) (see, for example, Patent Documents 1 and 2). Generally, the terminal resin film is fused to the metal terminal.

Japanese Patent No. 6706014 Japanese Patent No. 6402844

In recent years, as the capacity of batteries has increased, the thickness of metal terminals has been increasing, so there is a tendency to demand thicker resin films for terminals. However, when a conventional thin terminal resin film is made thick as it is, the adhesion of the terminal resin film to the metal terminal tends to decrease in a room temperature environment or a high temperature environment after coming into contact with the electrolytic solution. Easy to cause peeling.

The present disclosure has been made in view of the problems of the above-described conventional technology, and even when the film is thickened, it is excellent for terminals in room temperature and high temperature environments after contact with an electrolytic solution. An object of the present invention is to provide a terminal resin film having adhesiveness and an electric storage device using the same.

In order to achieve the above object, the present disclosure provides a terminal resin film arranged so as to cover a part of the outer peripheral surface of a metal terminal electrically connected to an electricity storage device main body that constitutes an electricity storage device, A resin film for terminals, wherein the resin film for terminals has the following layer A and a laminated structure, and the laminated structure comprises the following layer B, the following C layer, and the following B layer laminated in this order. offer.
Layer A: A layer formed using a resin composition containing an acid-modified polyolefin resin having a melting point of 100°C or higher and 170°C or lower.
Layer B: A layer formed using a resin composition containing a first polyolefin resin having a melting point of 100°C or higher and lower than 160°C and a second polyolefin resin having a melting point of 160°C or higher and 170°C or lower.
Layer C: A layer formed using a resin composition containing a polyolefin resin having a melting point of 160°C or higher and 170°C or lower.

According to the resin film for terminals, even if the resin film for terminals has the layer A and the laminated structure, even if the film is thickened, after contact with the electrolytic solution, And it becomes possible to have excellent adhesion to the terminal in a high-temperature environment.

In the terminal resin film, it is preferable that the B layer has a mass ratio R of the first polyolefin resin to the second polyolefin resin of 0.1 to 9. When the mass ratio R is 0.1 or more, the adhesiveness of the resin film for terminals to the terminals under a room temperature environment can be further improved after coming into contact with the electrolytic solution. Further, when the mass ratio R is 9 or less, the adhesiveness of the resin film for terminals to the terminals under high temperature environment can be further improved after coming into contact with the electrolytic solution.

In the terminal resin film, in the layer B, the first polyolefin resin has a tensile elastic modulus of 550 MPa or more and less than 1000 MPa and a tensile yield stress of 15 MPa or more and less than 23 MPa, and the second polyolefin resin has a tensile yield stress of 1000 MPa. It preferably has a tensile elastic modulus of 1500 MPa or more and a tensile yield stress of 23 MPa or more and 35 MPa or less. When the tensile elastic moduli of the first polyolefin resin and the second polyolefin resin are each equal to or higher than the above lower limit, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment can be further improved after coming into contact with the electrolytic solution. When the tensile yield stresses of the first polyolefin resin and the second polyolefin resin are equal to or higher than the above lower limit values, the adhesion of the terminal resin film to the terminals in a high-temperature environment after contact with the electrolytic solution can be further improved. Moreover, since the tensile elastic modulus of the first polyolefin resin is less than 1000 MPa, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. When the tensile elastic modulus of the second polyolefin resin is 1500 MPa or less, the adhesiveness of the terminal resin film to the terminals under room temperature environment can be further improved after contact with the electrolytic solution. When the tensile yield stress of the first polyolefin resin is less than 23 MPa, the adhesiveness of the terminal resin film to the terminal under room temperature can be further improved. When the tensile yield stress of the second polyolefin resin is 35 MPa or less, the adhesion of the terminal resin film to the terminal under room temperature can be further improved.

In the terminal resin film, in the layer B, the first polyolefin resin has a density of 885 kg/ ^m3 or more and less than 895 kg/m3, and the second polyolefin resin has a density of 895 kg/ ^m3 or ^more and 910 kg/m3. It preferably has a density of ³ or less. When the densities of the first polyolefin resin and the second polyolefin resin are equal to or higher than the above lower limit values, the adhesion of the terminal resin film to the terminals in a high-temperature environment can be further improved after contact with the electrolytic solution. When the density of the first polyolefin resin is less than the above upper limit, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. When the density of the second polyolefin resin is equal to or less than the above upper limit, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution.

In the terminal resin film, in the layer B, the first polyolefin resin has an MFR at 230° C. of 1.0 to 10.0 g/10 min, and the second polyolefin resin has an MFR of 0.05 g/10 min. It is preferably more than or equal to less than 1.0 g/10 min. When the MFR at 230° C. of the first polyolefin resin is 1.0 g/10 min or more, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. Further, when the MFR at 230° C. of the first polyolefin resin is 10.0 g/10 min or less, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment can be further improved after contact with the electrolytic solution. When the MFR at 230° C. of the second polyolefin resin is 0.05 g/10 min or more, the adhesion of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. Further, when the MFR at 230° C. of the second polyolefin resin is less than 1.0 g/10 min, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment can be further improved after coming into contact with the electrolytic solution.

It is preferable that the terminal resin film is formed by laminating the layer A, the laminated structure, and the layer A in this order. In this case, since the layer A is formed using a resin composition containing an acid-modified polyolefin resin, the adhesion between the metal terminal and the terminal resin film is further improved.

The terminal resin film may have a thickness of 160 μm or more.

The present disclosure also includes an electricity storage device body, a metal terminal electrically connected to the electricity storage device body, an exterior material that sandwiches the metal terminal and accommodates the electricity storage device body, and a part of the metal terminal. An electricity storage device is provided, comprising: the terminal resin film of the present disclosure, which covers an outer peripheral surface and is arranged between the metal terminal and the exterior material.

According to this electricity storage device, even when the resin film for terminals is thickened, it has excellent adhesion to the terminals in a room temperature environment and a high temperature environment after coming into contact with the electrolytic solution. Leakage of electrolyte can be suppressed under room temperature environment and high temperature environment.

According to the present disclosure, a resin film for terminals that has excellent adhesion to terminals in a room temperature environment and a high temperature environment after contact with an electrolytic solution even when the film is thickened; It is possible to provide an electricity storage device using the power storage device.

1 is a perspective view showing a schematic configuration of an electricity storage device according to this embodiment; FIG. FIG. 2 is a cross-sectional view showing an example of a cut surface of the exterior material shown in FIG. 1; FIG. 2 is a cross-sectional view of the terminal resin film and the metal terminal shown in FIG. 1 taken along the line AA. 1 is a schematic cross-sectional view showing an embodiment of a terminal resin film; FIG. FIG. 4 is a schematic diagram illustrating a method for preparing a sample for measuring heat seal strength against aluminum foil in Examples.

Preferred embodiments of the present disclosure will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[Power storage device]
FIG. 1 is a perspective view showing a schematic configuration of an electricity storage device according to this embodiment. In FIG. 1, a lithium ion secondary battery is illustrated as an example of the electricity storage device 10, and the following description will be given. Note that the lithium ion secondary battery configured as shown in FIG. 1 is sometimes called a battery pack, a battery cell, or the like.

The electricity storage device 10 shown in FIG. 1 is a lithium ion secondary battery, and includes an electricity storage device body 11, an exterior material 13, a pair of metal terminals 14 (tab leads), a terminal resin film 16 (tab sealant), have

The power storage device main body 11 is a battery main body that charges and discharges. The exterior material 13 covers the surface of the electricity storage device main body 11 and is arranged so as to be in contact with a portion of the terminal resin film 16 .

2 is a cross-sectional view showing an example of a cut surface of the exterior material shown in FIG. 1. FIG. In FIG. 2, the same components as those of the structure shown in FIG. 1 are denoted by the same reference numerals.

An example of the configuration of the exterior material 13 will be described with reference to FIG. 2 . The exterior material 13 includes an inner layer 21, an inner layer side adhesive layer 22, a corrosion prevention treatment layer 23-1, a barrier layer 24, a corrosion prevention treatment layer 23-2, from the inside in contact with the electricity storage device body 11, It has a seven-layer structure in which an outer layer side adhesive layer 25 and an outer layer 26 are sequentially laminated.

The inner layer 21 is a sealant layer that imparts heat-sealing properties to the exterior material 13 , and is a layer that is heat-sealed (heat-sealed) inside the power storage device 10 when the power storage device 10 is assembled. As the base material of the inner layer (sealant layer) 21, for example, a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with maleic anhydride or the like can be used. As the polyolefin resin, low-density, medium-density and high-density polyethylene; ethylene-α-olefin copolymer; homo, block or random polypropylene; propylene-α-olefin copolymer and the like can be used. Among these, the polyolefin resin preferably contains polypropylene. These polyolefin resins can be used singly or in combination of two or more.

The inner layer 21 may be a single layer film or a multi-layer film with multiple layers laminated together, depending on the function required. Specifically, it may be a multi-layer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed in order to impart moisture resistance. The inner layer 21 may contain various additives (flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers, etc.).

The thickness of the inner layer 21 is preferably 10-150 μm, more preferably 30-80 μm. When the thickness of the inner layer 21 is 10 μm or more, sufficient heat-sealing adhesion between the exterior materials 13 and sufficient adhesion with the terminal resin film 16 can be obtained. Moreover, since the thickness of the inner layer 21 is 150 μm or less, the cost of the exterior material 13 can be suppressed.

As the inner layer side adhesive layer 22, a known adhesive such as a dry lamination adhesive or an acid-modified heat-sealable resin can be appropriately selected and used.

As shown in FIG. 2, the corrosion prevention treatment layers 23-1 and 23-2 are preferably formed on both sides of the barrier layer 24 in terms of performance. The corrosion prevention treatment layer 23-1 may be arranged only on the surface of the barrier layer 24 that is to be exposed.

The barrier layer 24 may be a metal layer having electrical conductivity. Materials for the barrier layer 24 include aluminum, stainless steel, and the like, and aluminum is preferable from the viewpoint of cost, mass (density), and the like.

As the outer layer side adhesive layer 25, a polyurethane-based adhesive containing polyester polyol, polyether polyol, acrylic polyol, or the like as a main component can be used.

The outer layer 26 may be a single layer film such as nylon or polyethylene terephthalate (PET), or a multilayer film. Like the inner layer 21, the outer layer 26 may contain various additives (flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers, etc.). The outer layer 26 may have a protective layer formed by laminating an electrolyte-insoluble resin or coating an electrolyte-insoluble resin component in preparation for leakage of the electrolyte.

FIG. 3 is a cross-sectional view of the terminal resin film and the metal terminal shown in FIG. 1 taken along the line AA. In FIG. 3, the same components as those of the structure shown in FIG. 1 are denoted by the same reference numerals.

As shown in FIGS. 1 and 3, a pair (two in the case of FIG. 1) of metal terminals 14 has a metal terminal body 14-1 and a corrosion prevention layer 14-2. Of the pair of metal terminal bodies 14-1, one metal terminal body 14-1 is electrically connected to the positive electrode of the power storage device body 11, and the other metal terminal body 14-1 is connected to the power storage device body 11. is electrically connected to the negative electrode of The pair of metal terminal bodies 14 - 1 extend in a direction away from the power storage device body 11 and partially exposed from the exterior material 13 . The shape of the pair of metal terminal bodies 14-1 can be, for example, a flat plate shape.

Metal can be used as the material of the metal terminal body 14-1. The metal used as the material for the metal terminal main body 14-1 can be determined in consideration of the structure of the electricity storage device main body 11, the material of each component of the electricity storage device main body 11, and the like.

When the electricity storage device 10 is a lithium ion secondary battery, aluminum can be used as the positive electrode current collector, and copper can be used as the negative electrode current collector. When the electricity storage device 10 is a lithium ion secondary battery, the material of the metal terminal body 14-1 connected to the positive electrode of the electricity storage device body 11 is preferably aluminum. Further, from the viewpoint of corrosion resistance to the electrolytic solution, the material of the metal terminal main body 14-1 connected to the positive electrode of the electricity storage device main body 11 is more preferably an aluminum material with a purity of 97% or higher, such as 1N30. Furthermore, when bending the metal terminal main body 14-1, it is preferable to use an O material that has been tempered by sufficient annealing for the purpose of adding flexibility. The material of the metal terminal main body 14-1 connected to the negative electrode of the electricity storage device main body 11 is preferably copper or nickel with a nickel plating layer formed on the surface.

The thickness of the metal terminal body 14-1 can be determined according to the size and capacity of the lithium ion secondary battery. If the lithium ion secondary battery is small, the thickness of the metal terminal main body 14-1 may be 50 μm or more. In the case of a large-sized lithium ion secondary battery for power storage, in-vehicle use, etc., the thickness of the metal terminal main body 14-1 can be appropriately set within the range of 100 to 500 μm.

The corrosion prevention layer 14-2 is arranged to cover the surface of the metal terminal body 14-1. In the case of lithium ion secondary batteries, the electrolyte contains corrosive components such as _LiPF6 . The corrosion prevention layer 14-2 is a layer for suppressing corrosion of the metal terminal body 14-1 by corrosive components such as LiPF ₆ contained in the electrolyte.

[Resin film for terminals]
As shown in FIG. 3 , the terminal resin film 16 according to the present embodiment is arranged so as to partially cover the outer peripheral surface of the metal terminal 14 . The terminal resin film 16 has a layer A and a laminated structure, and the laminated structure is formed by laminating a layer B, a layer C, and a layer B in this order.
Layer A: A layer formed using a resin composition containing an acid-modified polyolefin resin having a melting point of 100°C or higher and 170°C or lower.
Layer B: A layer formed using a resin composition containing a first polyolefin resin having a melting point of 100°C or higher and lower than 160°C and a second polyolefin resin having a melting point of 160°C or higher and 170°C or lower.
Layer C: A layer formed using a resin composition containing a polyolefin resin having a melting point of 160°C or higher and 170°C or lower.

The melting points of the A layer, B layer and C layer are the values measured by a differential scanning calorimeter (DSC) according to ASTM D2117, and the peak top temperature with the peak having the largest heat of dissolution as the main peak can be obtained by reading When there are multiple melting peaks, the temperature at the peak with the greater heat of fusion.

FIG. 4 is a schematic cross-sectional view showing one embodiment of the terminal resin film according to the present embodiment. The terminal resin film 16 shown in FIG. 4 is formed by laminating an A layer 1, a laminated structure 8 and an A layer 7 in this order. Layers 6 are laminated in this order. That is, the terminal resin film 16 has a structure in which an A layer 1, a B layer 2, a C layer 4, a B layer 6 and an A layer 7 are laminated in this order. Each of the A layer, the B layer, and the C layer will be described below.

The A layer is formed using a resin composition containing an acid-modified polyolefin resin. Examples of acid-modified polyolefin resins include graft-modified resins obtained by graft-modifying maleic anhydride, carboxylic acid, sulfonic acid and their derivatives to polyolefin resins, olefins and maleic anhydride, carboxylic acids, sulfonic acids and their derivatives A copolymer resin obtained by copolymerizing is mentioned. Among them, a graft-modified resin is preferable from the viewpoint of adhesiveness to a metal terminal. The acid-modified polyolefin resin is preferably modified with maleic anhydride because it tends to improve the heat seal strength more than other modified groups. Examples of the polyolefin resins include low-density, medium-density, and high-density polyethylene; ethylene-α-olefin copolymers; homo, block, or random polypropylene; propylene-α-olefin copolymers; and norbornene. Among these, the polyolefin resin preferably contains polypropylene from the viewpoint of heat resistance, workability, and adhesion to the exterior material. As the acid-modified polyolefin resin, an acid-modified random polypropylene copolymer is preferred. These polyolefin resins may be used singly or in combination of two or more. Moreover, the resin composition used for forming the A layer may or may not contain other resins than the acid-modified polyolefin resin.

The acid modification rate of the polyolefin resin (for example, the mass of the portion derived from maleic anhydride with respect to the total mass of the maleic anhydride-modified polypropylene) is 0.1 to 20% by mass from the viewpoint of improving the heat seal strength. It is preferably 0.3 to 5% by mass, and more preferably 0.3 to 5% by mass.

The melting point of the acid-modified polyolefin resin used for the A layer is 100 to 170°C, preferably 120 to 160°C, even more preferably 130 to 150°C. By setting the melting point of the acid-modified polyolefin resin to 100° C. or higher, the adhesiveness of the terminal resin film to the metal terminal can be further improved in a high-temperature environment after contact with the electrolytic solution. Moreover, since the melting point of the acid-modified polyolefin resin is less than 170° C., the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution.

The resin composition used to form the A layer contains resin additives such as antioxidants, slip agents, flame retardants, light stabilizers, dehydrating agents, coloring pigments, tackifiers, fillers, and crystal nucleating agents. good too. A plurality of types of these additives may be blended. In particular, from the viewpoint of improving the visibility of the terminal resin film, the resin composition may contain a coloring pigment or a filler.

Examples of coloring pigments include carbon black, quinacridone-based pigments, polyazo-based pigments, isoindolinone-based pigments, and the like.

Fillers include aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, calcium carbonate, zirconium silicate, zinc oxide, barium sulfate, copper oxide, cobalt oxide, titanium oxide, tin oxide, iron oxide, antimony oxide, boron nitride, nitride Inorganic fillers such as aluminum and silicon nitride are included.

The thickness of layer A (thickness per layer) is preferably 10 to 150 μm, more preferably 15 to 100 μm, even more preferably 20 to 50 μm. When the thickness of the layer A is 10 µm or more, the adhesion between the metal terminal or the exterior material and the terminal resin film can be further improved in a high-temperature environment after contact with the electrolytic solution. In addition, the thickness of the layer A is preferably 150 μm or less from the viewpoint of workability and breaking strength of the film.

The MFR of the A layer at 230° C. is 2.0 to 50 g/10 min, preferably 3.0 to 25 g/10 min, more preferably 5.0 to 15 g/10 min. When the MFR of the layer A is 2.0 g/10 min or more, the elongation at break of the terminal resin film can be improved. Further, when the MFR of the layer A is 50 g/10 min or less, the breaking strength of the terminal resin film can be improved.

Layer B is formed using a resin composition containing a first polyolefin resin and a second polyolefin resin. Examples of the first polyolefin resin and the second polyolefin resin include low-, medium-, and high-density polyethylenes; ethylene-α-olefin copolymers; homo, block, or random polypropylenes; propylene-α-olefin copolymers; polybutene; polymethylpentene; polynorbornene; Among these, the first polyolefin resin and the second polyolefin resin preferably contain polypropylene from the viewpoint of heat seal strength and workability. The first polyolefin resin and the second polyolefin resin used in the B layer may be an acid-modified polyolefin resin or an unmodified polyolefin resin, but from the viewpoint of insulation, they should be unmodified polyolefin resin. is preferred. A random polypropylene copolymer is preferable as the first polyolefin resin, and a block polypropylene copolymer is preferable as the second polyolefin resin. Each of the first polyolefin resin and the second polyolefin resin may be used singly or in combination of two or more. Moreover, the resin composition used for forming the B layer may or may not contain resins other than the first polyolefin resin and the second polyolefin resin.

The melting point of the first polyolefin resin used in layer B is 100°C or higher and lower than 160°C, preferably 110 to 150°C, more preferably 120 to 140°C. When the melting point of the first polyolefin resin is 100° C. or higher, the adhesiveness of the terminal resin film to the metal terminal can be further improved in a high-temperature environment after contact with the electrolytic solution. Moreover, since the melting point of the first polyolefin resin is 160° C. or less, the adhesiveness of the resin film for terminals to the terminals under room temperature environment can be further improved after coming into contact with the electrolytic solution.

The melting point of the second polyolefin resin used in layer B is 160°C or higher and 170°C or lower, preferably 162°C or higher and 168°C or lower, and more preferably 163°C or higher and 166°C. When the melting point of the second polyolefin resin is 160° C. or higher, the adhesiveness of the resin film for terminals to the terminals in a high-temperature environment after contact with the electrolytic solution can be further improved. In addition, since the second polyolefin resin has a melting point of 170° C. or less, the adhesiveness of the terminal resin film to the terminals under room temperature can be further improved after contact with the electrolytic solution.

The resin composition used to form the B layer contains resin additives such as antioxidants, slip agents, flame retardants, light stabilizers, dehydrating agents, coloring pigments, tackifiers, fillers, and crystal nucleating agents. good too. A plurality of types of these additives may be blended. In particular, from the viewpoint of improving the visibility of the terminal resin film, the resin composition may contain a coloring pigment or a filler. As the coloring pigment and filler, the same ones as in the A layer can be used.

The thickness of the B layer (thickness per layer) is preferably 10 to 150 μm, more preferably 15 to 100 μm, even more preferably 20 to 50 μm. When the thickness of the layer B is 10 µm or more, the adhesion between the exterior material and the terminal resin film can be further improved in a high-temperature environment. From the standpoint of workability and breaking elongation of the film, the thickness of the B layer is preferably 150 μm or less.

In layer B, the mass ratio R of the first polyolefin resin to the second polyolefin resin is preferably 0.1 to 9, more preferably 0.3 to 8, and more preferably 0.5 to 7. More preferred. When R is 0.1 or more, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. In addition, when R is 9 or less, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment after contact with the electrolytic solution can be further improved.

In layer B, the first polyolefin resin has a tensile modulus of 550 MPa or more and less than 1000 MPa and a tensile yield stress of 15 MPa or more and less than 23 MPa, and the second polyolefin resin has a tensile modulus of 1000 MPa or more and 1500 MPa or less and 23 MPa. It is preferable to have a tensile yield stress of 35 MPa or more. When the tensile elastic moduli of the first polyolefin resin and the second polyolefin resin are each equal to or higher than the above lower limit, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment can be further improved after coming into contact with the electrolytic solution. When the tensile yield stresses of the first polyolefin resin and the second polyolefin resin are equal to or higher than the above lower limit values, the adhesion of the terminal resin film to the terminals in a high-temperature environment after contact with the electrolytic solution can be further improved. Moreover, since the tensile elastic modulus of the first polyolefin resin is less than 1000 MPa, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. When the tensile elastic modulus of the second polyolefin resin is 1500 MPa or less, the adhesiveness of the terminal resin film to the terminals under room temperature environment can be further improved after contact with the electrolytic solution. When the tensile yield stress of the first polyolefin resin is less than 23 MPa, the adhesiveness of the terminal resin film to the terminal under room temperature can be further improved. When the tensile yield stress of the second polyolefin resin is 35 MPa or less, the adhesion of the terminal resin film to the terminal under room temperature can be further improved.

The tensile elastic modulus of the first polyolefin resin is more preferably 570-750 MPa, even more preferably 600-700 MPa. The tensile yield stress of the first polyolefin resin is more preferably 16 MPa or more and 22 MPa or less, and even more preferably 17 to 21 MPa.

The tensile elastic modulus of the second polyolefin resin is more preferably 1100-1450 MPa, even more preferably 1300-1400 MPa. The tensile yield stress of the second polyolefin resin is more preferably 23-32 MPa, even more preferably 25-30 MPa.

In layer B, the first polyolefin resin preferably has a density of 885 kg/m ³ or more and less than 895 kg/m ³ , and the second polyolefin resin preferably has a density of 895 kg/m ³ or more and 910 kg/m ³ or less. When the densities of the first polyolefin resin and the second polyolefin resin are equal to or higher than the above lower limit values, the adhesion of the terminal resin film to the terminals in a high-temperature environment can be further improved after contact with the electrolytic solution. When the density of the first polyolefin resin is less than 895 kg/m ³ , the adhesiveness of the resin film for terminals to the terminals under room temperature environment can be further improved after contact with the electrolytic solution. When the density of the second polyolefin resin is 910 kg/m ³ or less, the adhesion of the resin film for terminals to the terminals under room temperature environment can be further improved after contact with the electrolytic solution.

The density of the first polyolefin resin is more preferably 885-893 kg/m ³ , still more preferably 887-891 kg/m ³ . More preferably, the density of the second polyolefin resin is 897-905 kg/m ³ .

The MFR of the first polyolefin resin of the B layer at 230° C. is 1.0 to 10.0 g/10 min, and the MFR of the second polyolefin resin of the B layer is 0.05 g/10 min or more and less than 1.0 g/10 min. Preferably. When the MFR at 230° C. of the first polyolefin resin is 1.0 g/10 min or more, the adhesiveness of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. Further, when the MFR at 230° C. of the first polyolefin resin is 10.0 g/10 min or less, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment can be further improved after contact with the electrolytic solution. When the MFR at 230° C. of the second polyolefin resin is 0.05 g/10 min or more, the adhesion of the terminal resin film to the terminal under room temperature environment can be further improved after contact with the electrolytic solution. Further, when the MFR at 230° C. of the second polyolefin resin is less than 1.0 g/10 min, the adhesiveness of the terminal resin film to the terminals in a high-temperature environment can be further improved after coming into contact with the electrolytic solution.

The MFR at 230° C. of the first polyolefin resin of layer B is more preferably 1.0 to 3.0 g/10 min, still more preferably 1.2 to 2.0 g/10 min. The MFR of the second polyolefin resin of layer B is more preferably 0.1 g/10 min or more and less than 1.0 g/10 min, and even more preferably 0.3 to 0.8 g/10 min.

The C layer is formed using a resin composition containing polyolefin resin. Examples of the unmodified polyolefin resin include low-density, medium-density, and high-density polyethylene; ethylene-α-olefin copolymer; homo, block, or random polypropylene; propylene-α-olefin copolymer; ; and polynorbornene. Among these, the polyolefin resin preferably contains polypropylene from the viewpoint of heat seal strength and workability. The polyolefin resin used for the C layer may be an acid-modified polyolefin resin or an unmodified polyolefin resin, but from the viewpoint of insulation, the unmodified polyolefin resin is preferable. A block polypropylene copolymer is preferable as the polyolefin resin. These polyolefin resins may be used singly or in combination of two or more. Moreover, the polyolefin resin used for the C layer is preferably the same as the second polyolefin resin used for the B layer from the viewpoint of interlayer adhesion between the C layer and the B layer. Furthermore, the resin composition used for forming the C layer may or may not contain other resins than the polyolefin resin. In addition, the resin composition used for forming the C layer contains only an unmodified polyolefin resin as a polyolefin resin and does not contain an acid-modified polyolefin resin. It is preferable from the viewpoint of adhesion with the terminal resin film.

The melting point of the polyolefin resin used for the C layer is 160 to 170°C, more preferably 160 to 165°C. By setting the melting point of the polyolefin resin to 160° C. or higher, it is possible to further improve the adhesion to the metal terminal 14 in a high-temperature environment after contact with the electrolytic solution. In addition, since the polyolefin resin has a melting point of 170° C. or less, the adhesiveness of the terminal resin film to the terminal can be further improved in a room temperature environment after contact with the electrolytic solution.

Assuming that the melting point of the polyolefin resin used for the C layer is Tm _C (°C) and the melting point of the polyolefin resin used for the B layer is Tm _B (°C), it is preferable to satisfy the condition of Tm _C ≧Tm _B. Further, the value of Tm _C −Tm _B is more preferably 1 to 25 (° C.), even more preferably 2 to 15 (° C.). By satisfying the condition of Tm _C ≧Tm _B , it is possible to further suppress a decrease in heat seal strength in a high-temperature environment after contact with the electrolytic solution. Further, when the value of Tm _C −Tm _B is 25 (° C.) or less, the workability of the terminal resin film can be improved.

The resin composition used to form the C layer contains resin additives such as antioxidants, slip agents, flame retardants, light stabilizers, dehydrating agents, coloring pigments, tackifiers, fillers, and crystal nucleating agents. good too. A plurality of types of these additives may be blended. In particular, from the viewpoint of improving the visibility of the terminal resin film, the resin composition may contain a coloring pigment or a filler. As the coloring pigment and filler, the same ones as in the A layer can be used.

The thickness of the C layer (thickness per layer) is preferably 2 to 150 μm, more preferably 3 to 100 μm, even more preferably 4 to 50 μm. When the thickness of the C layer is 2 μm or more, it is possible to improve the adhesion between the exterior material and the terminal resin film in a high-temperature environment after contact with the electrolytic solution. In addition, the thickness of the C layer is preferably 150 μm or less from the viewpoint of processability and breaking elongation of the film.

The MFR of the C layer at 230° C. is preferably 0.05 to 50 g/10 min, more preferably 1.0 to 25 g/10 min, even more preferably 2.0 to 15 g/10 min. When the C layer has an MFR of 0.05 g/10 min or more, the elongation at break of the terminal resin film can be improved. Moreover, since the MFR of the C layer is 50 g/10 min or less, the breaking strength of the terminal resin film can be improved.

The total thickness of the terminal resin film may be 160 μm or more, 175 μm or more, or 200 μm or more. Although the upper limit of the total thickness of the terminal resin film is not particularly limited, it may be, for example, 1000 μm or less.

Among the layers constituting the terminal resin film, when the total thickness of the layers corresponding to the A layers is T _A (μm) and the total thickness of the layers corresponding to the B layers is T _B (μm), It is preferable to satisfy the condition T _A ≧T _B. Further, the value of T _A /T _B is more preferably 1.0 to 1.5. When the value of T _A /T _B is within the above range, the heat seal strength can be further improved.

The ratio of the thickness of the laminated structure (layer B/layer C/layer B) to the total thickness of the terminal resin film is preferably 25 to 75%, more preferably 35 to 65%. When the thickness ratio of the laminated structure is 25% or more, the adhesiveness of the resin film for terminals to the terminals under room temperature environment can be further improved after coming into contact with the electrolytic solution. When the thickness ratio of the laminated structure is 75% or less, the adhesiveness of the resin film for terminals to the terminals in a high-temperature environment can be further improved after coming into contact with the electrolytic solution.

The ratio of the total thickness of the B layers in the laminated structure is preferably 30 to 80%, more preferably 40 to 70%. When the ratio of the total thickness of the layer B in the laminated structure is 30% or more, the adhesion of the terminal resin film to the metal terminal under a room temperature environment can be further improved after contact with the electrolytic solution. When the ratio of the total thickness of the layer B in the laminated structure is 80% or less, the adhesion of the terminal resin film to the metal terminal in a high-temperature environment after contact with the electrolytic solution can be further improved.

In the terminal resin film of the present embodiment, the plurality of A layers may be layers formed using the same resin or layers formed using different resins. Further, the plurality of A layers may be layers formed using the same resin composition, respectively, or layers formed using different resin compositions. Furthermore, the thickness, melting point and MFR of the multiple A layers may be the same or different. From the viewpoint of workability and curl suppression of the terminal resin film, it is preferable that all of the above-described configurations of the plurality of A layers are the same.

In the terminal resin film of the present embodiment, the plurality of B layers may be layers formed using the same resin or layers formed using different resins. Further, the plurality of B layers may be layers formed using the same resin composition, respectively, or layers formed using different resin compositions. Furthermore, the thickness, melting point and MFR of the multiple B layers may be the same or different. From the viewpoint of workability of the terminal resin film and curbing of curling, it is preferable that all of the above-described configurations of the plurality of B layers are the same.

In the terminal resin film of the present embodiment, when there are a plurality of C layers, the plurality of C layers may be layers formed using the same resin, or layers formed using different resins. There may be. Moreover, the plurality of C layers may be layers formed using the same resin composition, respectively, or layers formed using different resin compositions. Furthermore, the thickness, melting point and MFR of the multiple C layers may be the same or different. From the viewpoint of workability and curl suppression of the terminal resin film, it is preferable that all of the above-described configurations of the plurality of C layers are the same.

When the terminal resin film of the present embodiment has a laminated structure of A layer/B layer/C layer/B layer/A layer, each layer may have the same thickness or different thicknesses. The thickness ratio of each layer in the laminated structure may be such that the A layer is thicker than the B and C layers, such as 2:1:1:1:24:2:1:2:4. . The thickness ratio of each layer in the laminated structure is, for example, 1:1:1:1:3, from the viewpoint of filling the gap between the metal terminal and the terminal resin film. The thickness of the layer (A layer on the metal terminal side) may be made thicker. The C layer is preferably thinner than the A and B layers.

The terminal resin film of the present embodiment may contain layers other than the A layer, the B layer, and the C layer (layers that do not correspond to any of the A layer, the B layer, and the C layer). Preferably no layer is included. That is, it is preferable that all of the layers constituting the terminal resin film correspond to at least one layer selected from the group consisting of the A layer, the B layer and the C layer.

In the terminal resin film of the present embodiment, at least the outermost layer on the metal terminal side is preferably layer A from the viewpoint of adhesion. On the other hand, the outermost layer on the exterior material side may not be the A layer, and may be a layer using, for example, an unmodified polyolefin resin. All of the outermost layers are preferably A layers.

Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to specific embodiments, and various modifications can be made within the scope of the gist of the present disclosure described in the claims. Or change is possible.

[Method for producing terminal resin film]
Next, a method for manufacturing the terminal resin film 16 according to this embodiment will be described. The method for manufacturing the terminal resin film 16 is not limited to the following.

When the terminal resin film 16 has a five-layer structure of A layer/B layer/C layer/B layer/A layer, the five layers may be laminated by a coextrusion method, and a part of the layers may be formed in advance. After that, it may be laminated by a sandwich lamination method. For example, after forming a three-layer film consisting of A layer / B layer / C layer and A layer in advance, the three-layer film and A layer are laminated by a sandwich lamination method using a resin composition that constitutes B layer. Alternatively, a three-layer film consisting of A layer/B layer/C layer may be formed in advance, and a two-layer film consisting of B layer/A layer may be extruded thereon for lamination.

Alternatively, a three-layer film consisting of A layer/B layer/C layer may be formed in advance, and two three-layer films may be laminated by a dry lamination method using an adhesive composition. As the adhesive composition, from the viewpoint of interlayer adhesion between the C layers of the three-layer film, it is preferable to use one containing a resin of the same type as the polyolefin resin in the resin composition constituting the C layers. The resin of the same type is an unmodified polyolefin resin when the polyolefin resin in the resin composition constituting the C layer is an unmodified polyolefin resin, and when the polyolefin resin is an acid-modified polyolefin resin, It is an acid-modified polyolefin resin.

A three-layer film or the like that is formed in advance can be produced using a co-extrusion method such as a T-die extrusion method or an inflation method, but from the viewpoint of film thickness stability, it is possible to produce using an inflation method. preferable.

Even when the number of layers constituting the terminal resin film 16 is six or more, it can be manufactured by appropriately using the manufacturing method described above.

As an example of the method of manufacturing the terminal resin film 16, a method of manufacturing a five-layer film by the inflation method will be described.

First, base materials for the A layer, the B layer, the C layer, the B layer, and the A layer are prepared. Next, the base materials for the A layer, B layer, C layer, B layer and A layer are supplied to an inflation molding device. Next, while extruding the five base materials from the extrusion section of the inflation molding device, the five base materials are extruded so as to form a five-layer structure (a structure in which layers A, B, C, B, and A are laminated). Air is supplied from the inside of the laminate having a five-layer structure.

Then, while conveying the inflated cylindrical five-layer film, the five-layer film is flattened by the guide portion and then folded into a sheet by a pair of pinch rolls. Both ends of the folded tube are slit, and a pair (two strips) of the film is wound around a winding core to produce a roll-shaped five-layer film. Thus, the terminal resin film 16 is manufactured.

The extrusion temperature is preferably in the range of 130-300°C, more preferably 130-250°C. When the extrusion temperature is 130° C. or higher, the resin constituting each layer is sufficiently melted to reduce the melt viscosity, thereby stabilizing the extrusion from the screw. When the extrusion temperature is 300° C. or lower, it is possible to suppress oxidation and deterioration of the resin constituting each layer and prevent deterioration of the quality of the five-layer film.

The number of revolutions of the screw, the blow ratio, the take-up speed, etc. can be appropriately set in consideration of the film thickness. The film thickness ratio of each layer of the five-layer film can be adjusted by changing the number of rotations of each screw.

[Method of fusion-bonding resin film for terminals]
A fusion bonding process for fusion-bonding the terminal resin film 16 and the exterior material 13 shown in FIG. 4 will be described. A case will be described below in which the A layer 1 of the terminal resin film 16 shown in FIG. 4 faces the metal terminal side and the A layer 7 faces the exterior material side.

In the fusion process, the terminal resin film 16 and the exterior material 13 are thermally fused while simultaneously melting the A layer 7 by heating and adhering the A layer 7 to the exterior material 13 by pressure.

In the fusion bonding process, from the viewpoint of obtaining sufficient adhesion and sealing between the terminal resin film 16 and the exterior material 13, it is preferable to heat to a temperature equal to or higher than the melting point of the resin forming the A layer 7.

The temperature for heating the terminal resin film 16 may be, for example, 140 to 170.degree. The treatment time (the total time of heating time and pressurizing time) can be determined in consideration of adhesion to the exterior material and productivity. The processing time can be appropriately set within a range of 1 to 60 seconds, for example.

From the viewpoint of improving the production tact (productivity) of the resin film 16 for terminals, the heat-sealing may be performed at a temperature exceeding 170° C. for a short pressing time. In this case, the heating temperature can be, for example, higher than 170° C. and not higher than 230° C., and the pressing time can be, for example, 3 to 20 seconds.

Further, a fusion bonding process for fusion-bonding the terminal resin film 16 and the metal terminal 14 according to the present embodiment will be described with reference to FIG. In the fusion process, the terminal resin film 16 and the metal terminal 14 are thermally fused while simultaneously melting the A layer 1 by heating and adhering the A layer 1 to the metal terminal 14 by pressure.

In the fusion bonding process, it is preferable to heat the terminal resin film 16 and the metal terminal 14 to a temperature equal to or higher than the melting point of the resin forming the A layer 1 from the viewpoint of obtaining sufficient adhesion and sealing properties.

The temperature for heating the terminal resin film 16 may be, for example, 140 to 170.degree. Also, the treatment time (the total time of the heating time and the pressurizing time) can be determined in consideration of the adhesion to the metal terminal and productivity. The processing time can be appropriately set within a range of 1 to 60 seconds, for example.

From the viewpoint of improving the production tact (productivity) of the resin film 16 for terminals, heat sealing may be performed at a temperature exceeding 170° C. with a short pressing time. In this case, the heating temperature can be, for example, higher than 170° C. and not higher than 230° C., and the pressing time can be, for example, 3 to 20 seconds.

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

[Materials used]
Table 1 shows materials used in Examples and Comparative Examples. In Table 1, PP means polypropylene, acid-modified means maleic anhydride-modified, and melting point means the melting point of the resin used for each layer. The melting point is a value measured according to ASTM D2117, and when there are multiple melting peaks, the temperature at the peak with the greater heat of fusion. The tensile modulus and tensile yield stress are the results of measuring the terminal resin film by a tensile test conforming to JIS K7162 (specimen: 5B type specimen specified in JIS K7162, tensile speed: 50 mm / min). . Density is the result of measurement according to ISO 1183. MFR is the result of measuring the melt flow rate of each layer formed using each material with a melt flow rate measuring instrument (manufactured by Toyo Seiki Seisakusho Co., Ltd., measurement temperature: 230° C.) according to JIS K7210. In Table 1, B1-1 to B1-10 are collectively referred to as "B1" in some cases. B2-1 to B2-10 may be collectively referred to as "B2".

[Production of terminal resin film]
Using the materials shown in Tables 2 to 5, each layer having the thickness shown in the table was laminated in the order shown in the table to prepare a terminal resin film. A specific manufacturing method is as follows. In Tables 2 to 5, even for layers that do not satisfy the conditions of the A layer, B layer, or C layer of the present disclosure in terms of the presence or absence of acid modification or the melting point, the A layer and B layer are shown for convenience of comparison. Or classified into C layer. Moreover, in each example and each comparative example, the upper part indicates the constituent material, and the lower part indicates the thickness of each layer. As for the B layer, when the constituent material contains the first polyolefin resin and the second polyolefin resin, the mass content of the first polyolefin resin and the second polyolefin resin is also written in parentheses below the upper row.

(Examples 1 to 23)
Five layers of A layer/B layer/C layer/B layer/A layer are co-extruded and laminated by an inflation method, and a resin film for terminals having a five-layer structure of A layer/B layer/C layer/B layer/A layer got At this time, the extrusion temperature was 220°C.

(Comparative example 1)
A layer / B layer / C layer / B layer / A layer in the same manner as in Example 1 except that the B layer was changed to a layer consisting only of B1-1 when coextrusion was performed by the inflation method. A terminal resin film having a five-layer structure was obtained.

(Comparative example 2)
In the same manner as in Example 1, except that the three layers of B layer / C layer / B layer were changed to a single layer consisting of B1-1 when coextrusion was performed by the inflation method, A layer / B A terminal resin film having a three-layer structure of Layer/A layer was obtained.

(Comparative Example 3)
A layer / B layer in the same manner as in Example 1 except that the three layers of B layer / C layer / B layer were changed to a single layer consisting of B2-1 when coextrusion was performed by the inflation method. A terminal resin film having a three-layer structure of A layers was obtained.

(Comparative Example 4)
A five-layer structure of A layer / B layer / C layer / B layer / A layer in the same manner as in Example 1 except that the A layer was changed to a layer made of A6 when coextrusion was performed by the inflation method. A terminal resin film was obtained.

(Comparative Example 5)
A five-layer structure of A layer / B layer / C layer / B layer / A layer in the same manner as in Example 1 except that the A layer was changed to a layer made of A7 when coextrusion was performed by the inflation method. A terminal resin film was obtained.

(Comparative Example 6)
In the same manner as in Example 1 except that B1-1 was changed to B1-10 in the B layer when coextrusion was performed by the inflation method, 5 of A layer / B layer / C layer / B layer / A layer A terminal resin film having a layered structure was obtained.

(Comparative Example 7)
B2-1 was changed to B1-10 in one of the two B layers when coextrusion was performed by the inflation method, and B2-1 was changed to B2-2 in the other B layer. A terminal resin film having a five-layer structure of A layer/B layer/C layer/B layer/A layer was obtained in the same manner as in Example 1 except for the above.

(Comparative Example 8)
Five layers of A layer / B layer / C layer / B layer / A layer in the same manner as in Example 1 except that the C layer was changed from B2-1 to B1-5 when coextrusion was performed by the inflation method A terminal resin film having a structure was obtained.

(Comparative Example 9)
Five layers of A layer / B layer / C layer / B layer / A layer in the same manner as in Example 1 except that the C layer was changed from B2-1 to B2-10 when coextrusion was performed by the inflation method A terminal resin film having a structure was obtained.

[Adhesion to aluminum foil under room temperature environment after contact with electrolyte]
A sample of a terminal resin film cut to a size of 50 mm (TD) x 100 mm (MD) was folded in two so as to sandwich a chemically treated aluminum foil cut to a size of 50 mm x 50 mm. The ends were heat-sealed at 185°C/0.6 MPa/10 sec over a width of 10 mm. After that, the central portion in the longitudinal direction of the heat-sealed portion was cut out with a width of 15 mm (see FIG. 5) to prepare a sample for heat-sealing strength measurement. In this evaluation, the layered product 100 in FIG. 5 is a layered product composed of terminal resin film/aluminum foil/terminal resin film. This sample was immersed in the electrolytic solution and aged in an environment of 85° C. for one week. As the electrolytic solution, a mixed solution of ethylene carbonate/diethyl carbonate/dimethyl carbonate=1/1/1 (mass ratio) was adjusted to have a concentration of 1M with LiPF ₆ . After that, a T-peel test between the aluminum foil and the terminal resin film was performed using a tensile tester (manufactured by Shimadzu Corporation) under the conditions of a room temperature (25°C) environment and a tensile speed of 50 mm/min. did Based on the obtained results, the heat seal strength (burst strength) to aluminum foil (AL foil) was evaluated based on the following evaluation criteria. This evaluation result was used as an index of the adhesiveness of the terminal resin film to the terminal under the room temperature environment after contact with the electrolytic solution. If the evaluation is A, B or C, it is acceptable, and if it is D, it is unacceptable. The results are shown in Tables 2-5.
A: Heat seal strength is 30 N/15 mm or more B: Heat seal strength is 20 N/15 mm or more and less than 30 N/15 mm C: Heat seal strength is 15 N/15 mm or more and less than 20 N/15 mm D: Heat seal strength is less than 15 N/15 mm

[Adhesion to aluminum foil under high temperature environment after contact with electrolyte]
A sample of a terminal resin film cut to a size of 50 mm (TD) x 100 mm (MD) was folded in two so as to sandwich a chemically treated aluminum foil cut to a size of 50 mm x 50 mm. The ends were heat sealed at 185/0.6 MPa/10 sec over a width of 10 mm. After that, the central portion in the longitudinal direction of the heat-sealed portion was cut out with a width of 15 mm (see FIG. 5) to prepare a sample for heat-sealing strength measurement. In this evaluation, the layered product 100 in FIG. 5 is a layered product composed of terminal resin film/aluminum foil/terminal resin film. This sample was immersed in the electrolytic solution and aged in an environment of 85° C. for one week. As the electrolytic solution, a mixed solution of ethylene carbonate/diethyl carbonate/dimethyl carbonate=1/1/1 (mass ratio) was adjusted to have a concentration of 1M with LiPF ₆ . Thereafter, a T-peel test between the aluminum foil and the terminal resin film was performed using a tensile tester (manufactured by Shimadzu Corporation) under the conditions of a tension speed of 50 mm/min in an environment of 80°C. . Based on the obtained results, the heat seal strength (burst strength) to aluminum foil (AL foil) was evaluated based on the following evaluation criteria. This evaluation result was used as an index of adhesion of the terminal resin film to the terminal in a high-temperature environment after contact with the electrolytic solution. If the evaluation is A, B or C, it is acceptable, and if it is D, it is unacceptable. The results are shown in Tables 2-5.
A: Heat seal strength is 15 N/15 mm or more B: Heat seal strength is 12.5 N/15 mm or more and less than 15 N/15 mm C: Heat seal strength is 7 N/15 mm or more and less than 12.5 N/15 mm D: Heat seal strength is Less than 7N/15mm

1, 7... A layer, 2, 6... B layer, 4... C layer, 8... Laminated structure, 10... Power storage device, 11... Power storage device body, 13... Exterior material, 14... Metal terminal, 14-1... Metal Terminal body 14-2 Corrosion prevention layer 16 Terminal resin film 21 Inner layer 22 Inner layer side adhesive layer 23-1, 23-2 Corrosion prevention treatment layer 24 Barrier layer 25 Outer layer side adhesive layer, 26... Outer layer.

Claims (8)

A resin film for terminals disposed so as to cover a part of the outer peripheral surface of a metal terminal electrically connected to an electricity storage device main body constituting the electricity storage device,
The terminal resin film has the following layer A and a laminated structure,
The resin film for a terminal, wherein the laminated structure is formed by laminating the following layer B, the following layer C and the following layer B in this order.
Layer A: A layer formed using a resin composition containing an acid-modified polyolefin resin having a melting point of 100°C or higher and 170°C or lower.
Layer B: A layer formed using a resin composition containing a first polyolefin resin having a melting point of 100°C or higher and lower than 160°C and a second polyolefin resin having a melting point of 160°C or higher and 170°C or lower.
Layer C: A layer formed using a resin composition containing a polyolefin resin having a melting point of 160°C or higher and 170°C or lower. 2. The terminal resin film according to claim 1, wherein in said layer B, the mass ratio of said first polyolefin resin to said second polyolefin resin is 0.1-9. In the B layer, the first polyolefin resin has a tensile modulus of 550 MPa or more and less than 1000 MPa and a tensile yield stress of 15 MPa or more and less than 23 MPa,
The resin film for terminals according to claim 1 or 2, wherein the second polyolefin resin has a tensile elastic modulus of 1000 MPa or more and 1500 MPa or less and a tensile yield stress of 23 MPa or more and 35 MPa or less. In the B layer, the first polyolefin resin has a density of 885 kg/m ³ or more and less than 895 kg/m ³ ,
The resin film for terminals according to any one of claims 1 to 3, wherein the second polyolefin resin has a density of 895 kg/m ³ or more and 910 kg/m ³ or less. In the layer B, the first polyolefin resin has an MFR at 230° C. of 1.0 to 10.0 g/10 min,
5. The terminal resin film according to claim 1, wherein the second polyolefin resin has an MFR of 0.05 g/10 min or more and less than 1.0 g/10 min. 6. The terminal resin film according to claim 1, wherein the layer A, the laminated structure and the layer A are laminated in this order. 7. The terminal resin film according to claim 1, having a thickness of 160 μm or more. an electricity storage device main body;
a metal terminal electrically connected to the electricity storage device main body;
an exterior material that sandwiches the metal terminal and accommodates the power storage device main body;
The resin film for terminals according to any one of claims 1 to 7, which covers a part of the outer peripheral surface of the metal terminal and is arranged between the metal terminal and the exterior material, storage device.

Images