Insulating resin film for reeds, reeds with insulating resin film

Abstract

The present invention provides an insulating resin film for leads that, when applied to batteries, prevents a decrease in adhesive strength with conductors due to absorption and swelling of the electrolyte. [Solution] A first layer having a first surface and a second surface located opposite the first surface, The first layer comprises a second layer laminated on the second surface of the first layer, The first layer comprises a resin and a gelling agent, wherein the insulating resin film is for a lead.

Description

Technical Field

[0001] The present disclosure relates to an insulating resin film for leads and a lead with an insulating resin film.

Background Art

[0002] Patent Document 1 discloses a power storage device including at least a power storage device element having a positive electrode, a negative electrode, and an electrolyte, an exterior material for the power storage device that seals the power storage device element, and metal terminals that are electrically connected to each of the positive electrode and the negative electrode and protrude outside the exterior material for the power storage device, wherein an adhesive film for the metal terminal is interposed between the metal terminal and the exterior material for the power storage device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A laminated battery in which a laminate including a positive electrode, a separator, and a negative electrode is sealed together with an electrolytic solution in an exterior body has been conventionally used. In a laminated battery, in order to connect the positive electrode and the negative electrode to an external device, leads with insulating resin films are arranged so as to cross the sealing portion of the exterior body.

[0005] The lead with an insulating resin film has a plate-shaped conductor and insulating resin films for leads disposed on the upper and lower surfaces of the conductor, respectively. The insulating resin film for the lead has a function of adhering and sealing between the conductor and the exterior body by being thermocompression-bonded to the exterior body.

[0006] However, with conventional insulating resin films for leads, when the insulating resin film is heat-pressed onto a conductor to form an insulating resin film lead, and then heat-pressed onto an outer casing for use as a battery, it sometimes absorbs the electrolyte sealed inside the casing and swells in some areas. When a portion of the insulating resin film for leads swells, the adhesive strength between the conductor and the insulating resin film of the insulating resin film lead decreases, making it prone to peeling. Therefore, there has been a need for an insulating resin film for leads that can prevent the decrease in adhesive strength with the conductor due to absorption of electrolyte and swelling when applied to a battery.

[0007] The present disclosure aims to provide an insulating resin film for leads that, when applied to a battery, can prevent a decrease in adhesive strength with the conductor due to absorption and swelling of the electrolyte. [Means for solving the problem]

[0008] The insulating resin film for leads of the present disclosure comprises a first layer having a first surface and a second surface located opposite the first surface, and a second layer laminated on the second surface of the first layer, wherein the first layer comprises a resin and a gelling agent. [Effects of the Invention]

[0009] According to this disclosure, when applied to a battery, it is possible to provide an insulating resin film for leads that can prevent a decrease in adhesive strength with the conductor due to absorption and swelling of the electrolyte. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an explanatory diagram of a battery to which an insulating resin film-coated lead is applied according to one aspect of the present disclosure. [Figure 2] Figure 2 is a top view of a lead with an insulating resin film according to one embodiment of the present disclosure. [Figure 3] Figure 3 is a cross-sectional view along line AA in Figure 1. [Figure 4A] Figure 4A is a schematic cross-sectional view of an insulating resin film for a lead according to one aspect of the present disclosure. [Figure 4B] Figure 4B is a schematic cross-sectional view of an insulating resin film for a lead according to another aspect of the present disclosure. [Figure 5] Figure 5 shows the correlation between the amount of gelling agent added to the first layer and the ratio of the first loss coefficient. [Figure 6] Figure 6 is a table showing the evaluation results of the experimental examples. [Modes for carrying out the invention]

[0011] The implementation methods are described below.

[0012] [Description of Embodiments in this Disclosure] The embodiments of this disclosure are first listed and described. In the following description, the same or corresponding elements are denoted by the same reference numerals, and the same description of them is not repeated.

[0013] (1) An insulating resin film for a lead according to one aspect of the present disclosure comprises a first layer having a first surface and a second surface located opposite to the first surface, and a second layer laminated on the second surface of the first layer, wherein the first layer comprises a resin and a gelling agent.

[0014] In this specification, the insulating resin film for leads may also be referred to as "insulating resin film," and leads with insulating resin film attached may be referred to as "leads."

[0015] According to the inventors' research, when an insulating resin film is used as a lead and then as a battery, it was confirmed that the first layer is primarily responsible for absorbing and swelling the electrolyte.

[0016] The insulating resin film for leads according to one aspect of the present disclosure has a first layer containing a gelling agent, so that association or aggregation by the gelling agent or by the gelling agent and the resin occurs in the first layer, and it is considered that the gaps into which a liquid such as an electrolyte can penetrate between the molecules contained in the first layer are reduced. Therefore, according to the insulating resin film for leads according to one aspect of the present disclosure, even when applied to a battery, the first layer can prevent the absorption and swelling of the electrolyte and prevent a decrease in the adhesive force with the conductor.

[0017] (2) In the above (1), the content ratio of the gelling agent with respect to the resin in the first layer may be 0.05% by mass or more and 5.0% by mass or less.

[0018] By setting the content ratio of the gelling agent with respect to the resin in the first layer to 0.05% by mass or more, it is possible to particularly prevent the first layer and the insulating resin film from absorbing and swelling the electrolyte, and prevent a decrease in the adhesive force with the conductor.

[0019] By setting the content ratio of the gelling agent with respect to the resin in the first layer to 5.0% by mass or less, it is possible to prevent the gelling agent from being unevenly distributed or precipitating in the first layer.

[0020] (3) In the above (1), the content ratio of the gelling agent with respect to the resin in the first layer may be 0.2% by mass or more and 5.0% by mass or less.

[0021] By setting the content ratio of the gelling agent with respect to the resin in the first layer to 0.2% by mass or more, it is possible to particularly prevent the first layer and the insulating resin film from absorbing and swelling the electrolyte, and increase the adhesive strength with the conductor.

[0022] By setting the content ratio of the gelling agent with respect to the resin in the first layer to 5.0% by mass or less, it is possible to prevent the gelling agent from being unevenly distributed or precipitating in the first layer.

[0023] (4) In the above (1), the content ratio of the gelling agent with respect to the resin in the first layer may be 0.4% by mass or more and 5.0% by mass or less.

[0024] By setting the gelling agent content in the first layer resin to 0.4% by mass or more, the absorption of electrolyte and swelling of the first layer and the insulating resin film 1 are particularly prevented, and the adhesive strength with the conductor can be particularly enhanced.

[0025] By limiting the gelling agent content to 5.0% by mass or less in the resin of the first layer, it is possible to prevent the gelling agent from being unevenly distributed or precipitated within the first layer.

[0026] (5) In any of (1) to (4) above, the second layer may be crosslinked.

[0027] The cross-linking of the second layer makes the insulating resin film less susceptible to crushing when the leads are heat-pressed onto the outer casing, thereby increasing its mechanical strength.

[0028] (6) In any of (1) to (5) above, the gelling agent may include one or more selected from natural polysaccharides, saturated aliphatic hydroxycarboxylic acids, metal soaps, amino acid derivatives, diamide derivatives, and sorbitol-based gelling agents.

[0029] By including one or more gelling agents selected from natural polysaccharides, saturated aliphatic hydroxycarboxylic acids, metal soaps, amino acid derivatives, diamide derivatives, and sorbitol-based gelling agents, the gelling agents and resins can be easily aggregated within the first layer. This prevents the first layer and the insulating resin film for the leads from absorbing the electrolyte and swelling, thus preventing a decrease in adhesion to the conductor.

[0030] (7) In any of (1) to (6) above, the resin may include a polyolefin resin.

[0031] Polyolefin resins are thought to readily cooperate with gelling agents to cause association and aggregation. As a result, the gaps between molecules in the first layer into which liquids such as electrolytes can penetrate are particularly small, and even when an insulating resin film for leads according to one aspect of this disclosure is applied to a battery, it is possible to prevent the first layer from absorbing the electrolyte and swelling, thereby preventing a decrease in adhesion to the conductor.

[0032] Furthermore, the glass transition temperature and melting point of polyolefin resin are sufficiently high compared to the operating temperatures of various batteries, such as lithium-ion secondary batteries, to which leads having an insulating resin film according to one aspect of this disclosure are expected to be applied. For this reason, by including polyolefin resin in the first layer, the adhesion between the casing and the leads can be improved in batteries to which leads having an insulating resin film according to one aspect of this disclosure are applied. In addition, since a layer containing polyolefin resin is often arranged on the surface of the casing that contacts the leads, including polyolefin resin in the first layer also improves the adhesion between the leads having an insulating resin film according to one aspect of this disclosure and the casing.

[0033] (8) In any of (1) to (7) above, if the loss factor at an angular frequency of 0.01 rad / sec is defined as the first loss factor, the loss factor at an angular frequency of 0.1 rad / sec as the second loss factor, the loss factor at an angular frequency of 10 rad / sec as the third loss factor, and the loss factor at an angular frequency of 100 rad / sec as the fourth loss factor, and the ratio of the first loss factor to the third loss factor is defined as the first loss factor ratio, then the first layer may have a first loss factor ratio of less than 4.5 at 160°C.

[0034] The first loss factor, which is the loss factor in the region of low angular frequency of 0.01 rad / sec, is mainly the loss factor for large molecules with low mobility. The loss factor is an indicator of the balance between viscosity and elasticity, and the smaller the value of the first loss factor, the higher the proportion of elasticity, meaning that the gelling agent, or the gelling agent and resin, aggregate to form strong aggregated particles, and the gaps through which the electrolyte can penetrate are particularly small.

[0035] The loss coefficient of the first layer is also affected by the type of material contained in the first layer, so the ratio of the first loss coefficient to the third loss coefficient is used as an indicator. By setting the first loss coefficient ratio to less than 4.5, the gelling agent and the gelling agent and resin aggregate, forming strong aggregated particles, and the gaps into which the electrolyte can penetrate can be made particularly small. Therefore, even when applied to a battery, it is possible to prevent the first layer from absorbing the electrolyte and swelling, and to prevent a decrease in adhesion to the conductor.

[0036] (9) In any of (1) to (8) above, if the loss coefficient at an angular frequency of 0.01 rad / sec is defined as the first loss coefficient, the loss coefficient at an angular frequency of 0.1 rad / sec as the second loss coefficient, the loss coefficient at an angular frequency of 10 rad / sec as the third loss coefficient, and the loss coefficient at an angular frequency of 100 rad / sec as the fourth loss coefficient, and the ratio of the second loss coefficient to the fourth loss coefficient is defined as the second loss coefficient ratio, then the first layer may have a second loss coefficient ratio of less than 5.5 at 160°C.

[0037] The second loss factor, which is the loss factor in the region of low angular frequency (0.1 rad / sec), is mainly the loss factor for large molecules with low mobility. The loss factor is an indicator of the balance between viscosity and elasticity, and the smaller the value of the second loss factor, the higher the proportion of elasticity, meaning that the gelling agent, or the gelling agent and resin, aggregate to form strong aggregated particles, and the gaps through which the electrolyte can penetrate are particularly small.

[0038] The loss coefficient of the first layer is also affected by the type of material contained in the first layer, so the ratio of the second loss coefficient to the fourth loss coefficient is used as an indicator. By setting the second loss coefficient ratio to less than 5.5, the gelling agent and the gelling agent and resin aggregate, forming strong aggregated particles, and the gaps into which the electrolyte can penetrate can be made particularly small. Therefore, even when applied to a battery, it is possible to prevent the first layer from absorbing the electrolyte and swelling, and to prevent a decrease in adhesion to the conductor.

[0039] (10) An insulating resin film lead according to one aspect of the present disclosure comprises a plate-shaped conductor having a rectangular upper and lower surface, a first insulating resin film disposed on the upper surface of the conductor, and a second insulating resin film disposed on the lower surface of the conductor, wherein the first insulating resin film and the second insulating resin film are insulating resin films for leads according to any one of (1) to (9), and the conductor, the first layer, and the second layer are laminated in that order.

[0040] In one aspect of the present disclosure, the insulating resin film according to one aspect of the present disclosure is heat-pressed onto a conductor.

[0041] According to one aspect of the present disclosure, even when applied to a battery, the first layer is prevented from absorbing the electrolyte and swelling, thereby preventing a decrease in adhesion to the conductor.

[0042] Therefore, according to one aspect of the present disclosure, when applied to a battery, it is possible to prevent the conductor and the insulating resin film from peeling off, thereby improving durability.

[0043] [Details of the embodiments of this disclosure] Specific examples of an insulating resin film for leads and leads with insulating resin films according to one embodiment of this disclosure (hereinafter referred to as "this embodiment") will be described below with reference to the drawings. However, the present invention is not limited to these examples and is intended to be shown in the claims, with all modifications within the meaning and scope of equivalence to the claims being included.

[0044] In this specification, the names of components and characteristic values ​​may be described with prefixes such as "1st," "2nd," etc., such as "1st layer," "2nd layer," "1st insulating resin film," "2nd insulating resin film," "1st loss coefficient," and "2nd loss coefficient." The prefixes "1st," "2nd," etc., are merely used to identify each component and characteristic value and to prevent confusion during explanation; they do not indicate arrangement or priority. Therefore, when there is no particular risk of confusion or when they are shown together, they can simply be described as "layer," "insulating resin film," and "loss coefficient." [Insulating resin film for leads] Figure 1 is an explanatory diagram of a battery to which an insulating resin film-coated lead having an insulating resin film for the lead of this embodiment is applied. Figure 2 is a top view of the insulating resin film-coated lead having an insulating resin film of this embodiment. Figure 3 is a schematic cross-sectional view along line AA in Figure 1.

[0045] Figure 4A is a schematic cross-sectional view of an insulating resin film according to one aspect of the present disclosure. Figure 4B is a schematic cross-sectional view of an insulating resin film according to another aspect of the present disclosure.

[0046] First, we will describe the lead with an insulating resin film equipped with the insulating resin film of this embodiment, and the battery using the lead. (1) About batteries As shown in Figure 1, the battery 10 may have an outer casing 11, an electrode stack 12 in which a positive electrode, a separator, and a negative electrode are stacked and impregnated with an electrolyte, and leads 13 connected to the electrode stack 12. (Exterior) The outer casing 11 is a container that houses and seals the electrode stack 12 and the electrolyte. The outer casing 11 may have at least one resin layer on the surface facing the electrode stack 12 so that it can be heat-sealed.

[0047] The exterior body 11 can have a structure in which a first resin layer 111, a metal layer 112, and a second resin layer 113 are laminated, as shown in Figure 3, for example.

[0048] As shown by the dashed line in Figure 1, a sealing portion 110 is formed around the periphery of the outer casing 11, and the electrode stack 12 and electrolyte are sealed by the sealing portion 110. The area enclosed by the sealing portion 110 is the area sealed by the outer casing 11. (2) Regarding leads with insulating resin film As shown in Figures 1, 2, and 3, the insulating resin film-covered lead 13 of this embodiment may have a plate-shaped conductor 14 having a rectangular upper surface 141 and a lower surface 142, and an insulating resin film 15. The insulating resin film 15 includes a first insulating resin film 151 disposed on the upper surface 141 of the conductor 14, and a second insulating resin film 152 disposed on the lower surface 142 of the conductor 14.

[0049] The conductor 14 and insulating resin film 15, which are components of the lead 13, will now be described. (2-1) Conductor The conductor 14 is a component for connecting the electrode stack 12, which is placed inside the outer casing 11, with the equipment placed outside the outer casing 11. The conductor 14 can be plate-shaped, and its upper surface 141 and lower surface 142 (see Figure 3) may have a rectangular shape. As shown in Figure 2, the upper surface 141 of the conductor 14 has two opposing sides, sides 21 and 22, and sides 23 and 24 that intersect sides 21 and 22. However, the rectangular shape does not mean a geometrically strict shape, and the conductor 14 may have rounded corners.

[0050] In the following explanation, the conductor 14 is viewed from above along the vertical direction of the top surface 141, and the axis along the two selected opposing sides, sides 21 and 22, is defined as the X-axis. The axis perpendicular to the X-axis is defined as the Y-axis.

[0051] The material of the conductor 14 is not particularly limited, and various materials used for lead conductors can be used, for example. Examples of materials for the conductor 14 include metallic materials such as aluminum, titanium, nickel, copper, aluminum alloys, titanium alloys, nickel alloys, and copper alloys, as well as materials made by plating these metallic materials with nickel, gold, etc. (2-2) Insulating resin film As shown in Figure 3, the insulating resin film 15 may include a first insulating resin film 151 positioned on the upper surface 141 of the conductor 14, and a second insulating resin film 152 positioned on the lower surface 142 of the conductor 14. As shown in Figures 2 and 3, on the upper surface 141 and the lower surface 142, the first insulating resin film 151 and the second insulating resin film 152 are positioned so that they do not cover the ends of the conductor 14 along the Y-axis, i.e., the ends including sides 21 and 22, but leave them exposed. Therefore, on the upper surface 141 and the lower surface 142 of the conductor 14, the first insulating resin film 151 and the second insulating resin film 152 are positioned to cover the intermediate portion of the conductor 14, which is the portion of the conductor 14 other than the ends along the Y-axis, crossing the conductor 14 along the X-axis.

[0052] The upper surface 141 and lower surface 142 of the conductor 14 refer to the surfaces that face the outer casing 11 of the battery 10 when the battery 10 is manufactured.

[0053] Of the conductor 14, the ends along the Y-axis refer to the first end region 25 including side 21 and the second end region 26 including side 22, as shown in Figure 2. The intermediate portion is the part located between the first end region 25 and the second end region 26.

[0054] The first end region 25 is the part that is exposed to the outside of the casing 11 when the lead 13 is applied to the battery, and its size can be selected to allow connection to external equipment. The second end region 26 is the part that is located inside the casing 11 when the lead 13 is applied to the battery, and is connected to the electrode stack 12, and its size can be selected to allow connection to the electrode stack 12. The first end region 25 and the second end region 26 may have the same area or different dimensions.

[0055] Therefore, the length L14 of the conductor 14 along the Y-axis may be longer than the length L15 of the insulating resin film 15. Also, the length W15 of the insulating resin film 15 may be longer than the length W14 of the conductor 14 along the X-axis.

[0056] The first insulating resin film 151 and the second insulating resin film 152 may be arranged so as shown in Figure 2, that they extend beyond both ends of the conductor along the X-axis and overlap. In the portions that extend beyond the conductor 14, the first insulating resin film 151 and the second insulating resin film 152 may be in direct contact and bonded together. (3) Regarding insulating resin film for leads The insulating resin film 15 is placed in the portion of the lead 13 that comes into contact with the outer casing 11, and is bonded to the conductor 14 by heat compression to form the lead 13. The lead 13 can be tightly attached to the sealing portion 110 (see Figure 1) at the insulating resin film 15 portion.

[0057] Conventional insulating resin films 15, when used as a battery by heat-pressing them onto an outer casing 11 after being used as leads 13, sometimes absorbed the electrolyte sealed inside the outer casing 11 and partially swelled. When a portion of the insulating resin film 15 swells, the adhesive strength between the conductor 14 of the leads 13 and the insulating resin film 15 decreases, making them prone to peeling. Therefore, there was a need for an insulating resin film that could prevent the decrease in adhesive strength with the conductor 14 due to absorption of electrolyte and swelling when applied to a battery.

[0058] As shown in Figures 4A and 4B, the insulating resin film 15 of this embodiment can have a structure in which multiple layers containing resin are laminated. For example, as shown in Figure 4A, the insulating resin film 15 can have a structure in which a first layer 31 and a second layer 32 are laminated. Also, as shown in Figure 4B, the insulating resin film 15 can have a third layer 33 in addition to the first layer 31 and the second layer 32. The insulating resin film 15 can also have a structure in which four or more layers are laminated.

[0059] If the insulating resin film 15 has multiple layers, each layer can be functionally separated. If the insulating resin film 15 contains two layers, for example, the first layer 31 may be an adhesive layer that adheres to the conductor 14. The second layer 32 may be a heat-resistant layer that makes the lead 13 less likely to be crushed when heat-pressed to the outer casing 11 and increases its mechanical strength. As shown in Figure 4B, if the insulating resin film 15 further has a third layer 33, the third layer 33 may be an adhesion layer that improves adhesion to the outer casing 11.

[0060] According to the inventors' investigation of the present invention, when the insulating resin film 15 is used as a lead 13 and then used as a battery, it was confirmed that the electrolyte is mainly absorbed and swelled in the first layer 31.

[0061] Based on the above findings, the inventors of the present invention conducted further studies. As a result, they found that the inclusion of a gelling agent in the first layer 31 prevents the insulating resin film 15 from absorbing and swelling the electrolyte when used as a battery after being made into a lead 13, thereby preventing a decrease in adhesion strength with the conductor, and thus completed the present invention.

[0062] As shown in Figures 4A and 4B, the insulating resin film 15 of this embodiment may have a first layer 31 having a first surface 400 exposed to the outside and a second surface 401 located opposite the first surface 400, and a second layer 32 laminated on the second surface 401 of the first layer 31.

[0063] The first surface 400 of the first layer 31 is the surface that is thermocompressed onto the conductor 14. The second surface 401 of the first layer 31 is the interface with the second layer 32.

[0064] The following explains each layer. (3-1) Characteristics and materials of each layer (3-1-1) 1st layer (3-1-1-1) Regarding the material of the first layer The first layer 31 may contain a resin and a gelling agent. (resin) The first layer 31 may contain a thermoplastic resin so that it can be heat-pressed onto the conductor 14. As the thermoplastic resin, one or more types selected from, for example, polyolefin resin, polyester resin, polystyrene resin, and polyvinyl chloride resin can be used. Examples of polyolefin resins include polyethylene, polypropylene, acid-modified polyethylene, and acid-modified polyolefin resins such as acid-modified polypropylene. Examples of polyester resins include polyethylene terephthalate resin. Examples of acid-modified polyolefins include maleic anhydride-modified polyolefins.

[0065] The resin contained in the first layer 31 may include a polyolefin resin. Polyolefin resins are thought to readily cooperate with gelling agents to cause association and aggregation. As a result, the gaps between molecules in the first layer 31 into which liquids such as electrolytes can penetrate are particularly small, and even when the insulating resin film 15 of this embodiment is applied to a battery, the first layer 31 is prevented from absorbing the electrolyte and swelling, thereby preventing a decrease in adhesion to the conductor 14.

[0066] Furthermore, the glass transition temperature and melting point of polyolefin resin are sufficiently high compared to the operating temperatures of various batteries, such as lithium-ion secondary batteries, to which the lead having the insulating resin film 15 of this embodiment is intended to be applied. Therefore, by including polyolefin resin in the first layer 31, the adhesion between the casing and the lead can be improved in a battery to which the lead having the insulating resin film 15 of this embodiment is applied. In addition, since a layer containing polyolefin resin is often arranged on the surface of the casing that contacts the lead, the adhesion between the lead having the insulating resin film 15 of this embodiment and the casing can also be improved by including polyolefin resin in the first layer 31. (Gelling agent) The first layer 31 may contain a gelling agent.

[0067] In this embodiment, the insulating resin film 15 contains a gelling agent in the first layer 31, which is thought to cause association or aggregation of the gelling agent or the gelling agent and resin within the first layer 31, reducing the gaps between molecules in the first layer 31 that allow liquids such as electrolytes to penetrate. Therefore, even when applied to a battery, the insulating resin film 15 of this embodiment prevents the first layer 31 from absorbing the electrolyte and swelling, thus preventing a decrease in adhesion to the conductor.

[0068] The type of gelling agent contained in the first layer 31 is not particularly limited, and it may contain various gelling agents. The first layer 31 may contain one or more gelling agents selected from, for example, natural polysaccharides, saturated aliphatic hydroxycarboxylic acids, metal soaps, amino acid derivatives, diamide derivatives, and sorbitol-based gelling agents.

[0069] By including one or more gelling agents selected from natural polysaccharides, saturated aliphatic hydroxycarboxylic acids, metal soaps, amino acid derivatives, diamide derivatives, and sorbitol-based gelling agents, the gelling agents and resins can be easily aggregated within the first layer 31. This prevents the first layer 31 and the insulating resin film 15 from absorbing the electrolyte and swelling, thereby preventing a decrease in adhesion to the conductor 14.

[0070] Examples of natural polysaccharides include agar. Examples of saturated aliphatic hydroxycarboxylic acids include 10-hydroxystearic acid. Examples of metal soaps include calcium dehydroabiethinate and aluminum stearate. Examples of amino acid derivatives include N-benzyloxycarbonyl-L-valine derivatives. Examples of diamide derivatives include trans-1,2-diaminocyclohexane-diamide derivatives. Examples of sorbitol-based gelling agents include 1,3:2,4-di-O-benzylidene-D-sorbitol (DBS), 1,3:2,4-di-Op-methylbenzylidene-D-sorbitol (MDBS), and 1,3:2,4-di-Om,p-dimethylbenzylidene-D-sorbitol (DMDBS).

[0071] The proportion of the gelling agent in the first layer 31 relative to the resin is not particularly limited, but may be, for example, 0.05% by mass or more and 5.0% by mass or less.

[0072] By setting the gelling agent content ratio of the resin in the first layer 31 to 0.05% by mass or more, it is particularly effective in preventing the first layer 31 and the insulating resin film 15 from absorbing the electrolyte and swelling, thereby preventing a decrease in adhesive strength with the conductor 14. The gelling agent content ratio of the resin in the first layer 31 may be 0.1% by mass or more, 0.2% by mass or more, or 0.4% by mass or more. By setting the gelling agent content ratio of the resin in the first layer 31 to 0.1% by mass or more, it is particularly effective in preventing the first layer 31 and the insulating resin film 15 from absorbing the electrolyte and swelling, thereby particularly effective in preventing a decrease in adhesive strength with the conductor 14. By setting the gelling agent content ratio of the resin in the first layer 31 to 0.2% by mass or more, it is particularly effective in preventing the first layer 31 and the insulating resin film 15 from absorbing the electrolyte and swelling, thereby increasing the adhesive strength with the conductor 14. By setting the gelling agent content in the resin of the first layer 31 to 0.4% by mass or more, the absorption of electrolyte and swelling of the first layer 31 and the insulating resin film 15 are particularly prevented, and the adhesive strength with the conductor 14 is particularly enhanced.

[0073] By setting the gelling agent content ratio in the first layer 31 to 5.0% by mass or less, it is possible to prevent the gelling agent from being unevenly distributed or precipitated within the first layer.

[0074] The gelling agent content in the resin of the first layer 31 may be 1.0% by mass or less, or 0.8% by mass or less. By setting the gelling agent content in the resin of the first layer 31 to 1.0% by mass or less, the adhesive strength of the first layer 31 and the insulating resin film 15 to the conductor 14 can be increased. Furthermore, by setting the gelling agent content in the resin of the first layer 31 to 0.8% by mass or less, the adhesive strength of the first layer 31 and the insulating resin film 15 to the conductor 14 can be particularly increased.

[0075] Therefore, the content ratio of the gelling agent to the resin of the first layer 31 may be 0.05% by mass or more and 5.0% by mass or less, 0.2% by mass or more and 5.0% by mass or less, or 0.4% by mass or more and 5.0% by mass or less. Furthermore, the content ratio of the gelling agent to the resin of the first layer 31 may be, for example, 0.05% by mass or more and 1.0% by mass or less, 0.2% by mass or more and 1.0% by mass or less, or 0.4% by mass or more and 0.8% by mass or less. (Additives) The first layer 31 may also contain any additives other than the thermoplastic resin and gelling agent. Examples of additives include one or more selected from crosslinking agents, flame retardants, ultraviolet absorbers, light stabilizers, heat stabilizers, lubricants, colorants, etc.

[0076] Crosslinking agents will be explained as an example of additives. (Crosslinking agent) The first layer 31 may be crosslinked. The loss coefficient tanδ of the first layer 31 can be selected not only by the amount of gelling agent added, but also by the materials contained in the first layer 31 and the degree of crosslinking of the first layer 31.

[0077] The inclusion of a crosslinking agent in the first layer 31 allows for crosslinking of the first layer 31, and the degree of crosslinking of the first layer 31 can be easily controlled by adjusting the proportion of the crosslinking agent. Therefore, the inclusion of a crosslinking agent in the first layer 31 also allows for control of the loss coefficient of the first layer 31.

[0078] The crosslinking agent contained in the first layer 31 is not particularly limited and can be selected according to the crosslinking method, etc. The crosslinking agent may include, for example, a compound containing at least two unsaturated groups in its molecule. As the crosslinking agent, one or more selected from, for example, triallyl isocyanurate (TAIC®), trimethylolpropane trimethacrylate, tris(2-acryloyloxyethyl) isocyanurate, etc., may be used. The blending ratio of the crosslinking agent in the first layer 31 is not particularly limited, but may be more than 0 parts by mass and 10 parts by mass or less, or 0.1 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the resin component.

[0079] The insulating resin film 15 may also include a second layer 32, as shown in Figures 4A and 4B. The second layer 32 may be a heat-resistant layer that makes the lead 13 less likely to be crushed when heat-pressed to the outer casing 11 and increases its mechanical strength. For this reason, the degree of crosslinking of the second layer 32 may be equal to or greater than that of the first layer 31.

[0080] Therefore, the proportion of the crosslinking agent in the first layer 31 by mass may be less than or equal to the proportion of the crosslinking agent in the second layer 32 by mass.

[0081] The degree of crosslinking in each layer can be controlled by the amount of electron beam irradiation used during crosslinking, the mixing ratio of the crosslinking agent in each layer, and other factors.

[0082] The method for crosslinking the first layer 31 is not particularly limited, and crosslinking may be performed, for example, by irradiation with ionizing radiation such as accelerated electron beams or gamma rays. (3-1-1-2) Regarding the loss coefficient ratio of the first layer In the following explanation, the loss factor at an angular frequency of 0.01 rad / sec will be referred to as the first loss factor, and the loss factor at an angular frequency of 0.1 rad / sec will be referred to as the second loss factor. Furthermore, the loss factor at an angular frequency of 10 rad / sec will be referred to as the third loss factor, and the loss factor at an angular frequency of 100 rad / sec will be referred to as the fourth loss factor. (Ratio of the first loss factor) The ratio of the first loss factor to the third loss factor is defined as the first loss factor ratio. In this case, the first layer 31 may have a first loss factor ratio of less than 4.5 at 160°C.

[0083] The loss factor, tanδ, is the ratio of the loss modulus (G'') to the storage modulus (G''). That is, the loss factor can be calculated using the following equation (1).

[0084] Loss coefficient (tanδ) = Loss modulus (G'') ÷ Storage modulus (G'') ... (1) The storage modulus (G') represents elasticity and is the component of energy stored internally from the energy generated in an object by external force and strain.

[0085] The loss modulus (G'') represents viscosity and is the component of energy generated in an object by external force and strain that is diffused to the outside due to heat generation, etc.

[0086] The loss factor tanδ is an index that represents the balance between viscosity and elasticity. A larger loss factor indicates greater viscosity, while a smaller value indicates greater elasticity.

[0087] The reason the temperature used to measure the loss coefficient is 160°C is that it is selected as a temperature that allows the resin and gelling agent contained in the first layer 31 to soften to a degree that the effects of angular frequency can be reflected.

[0088] The first loss factor, which is the loss factor in the region of low angular frequency of 0.01 rad / sec, is mainly the loss factor for large molecules with low mobility. As mentioned above, the loss factor is an indicator of the balance between viscosity and elasticity, and the smaller the value of the first loss factor, the higher the proportion of elasticity, meaning that the gelling agent, or the gelling agent and resin, aggregate to form strong aggregated particles, and the gaps through which the electrolyte can penetrate are particularly small.

[0089] Since the loss coefficient of the first layer 31 is also affected by the type of material contained in the first layer 31, the first loss coefficient ratio, which is the ratio of the first loss coefficient to the third loss coefficient calculated by the following equation (2), is used as an indicator.

[0090] As mentioned above, in terms of the loss coefficient, the smaller the angular frequency, the more the loss coefficient mainly relates to large molecules with low mobility, and the differences in the degree of gelation are more easily expressed. The inventors of this invention measured the loss coefficient at various angular frequencies for samples with different degrees of gelation by changing the amount of gelling agent added. As a result, as the angular frequency increases, the effect of the degree of gelation decreases, and at the third loss coefficient at an angular frequency of 10 rad / sec and the fourth loss coefficient at an angular frequency of 100 rad / sec, there is almost no difference in the value of the loss coefficient due to the degree of gelation. For this reason, the first loss coefficient ratio and the second loss coefficient ratio use the third loss coefficient at an angular frequency of 10 rad / sec and the fourth loss coefficient at an angular frequency of 100 rad / sec as references. (Ratio of the first loss factor) = (First loss factor) / (Third loss factor) ... (2) Furthermore, by setting the first loss coefficient ratio to less than 4.5, the gelling agent and the gelling agent and resin aggregate, forming strong aggregated particles, which significantly reduces the gaps through which the electrolyte can penetrate. Therefore, even when applied to a battery, the first layer is prevented from absorbing the electrolyte and swelling, thus preventing a decrease in adhesion to the conductor.

[0091] The lower limit of the first loss factor ratio is not particularly limited, but one way to reduce the first loss factor ratio is to increase the amount of gelling agent added. However, if the amount of gelling agent added is increased, the gelling agent may precipitate in the first layer 31. For this reason, the first loss factor ratio can be set to, for example, 1.2 or higher.

[0092] The first loss factor ratio may be, for example, 1.2 or more and less than 4.5, or 1.5 or more and 4.0 or less. (Second loss factor ratio) The ratio of the second loss factor to the fourth loss factor is defined as the second loss factor ratio. In this case, the first layer 31 may have a second loss factor ratio of less than 5.5 at 160°C.

[0093] The second loss factor, which is the loss factor in the region of low angular frequency of 0.1 rad / sec, is mainly the loss factor for large molecules with low mobility. As mentioned above, the loss factor is an indicator of the balance between viscosity and elasticity, and the smaller the value of the second loss factor, the higher the proportion of elasticity, meaning that the gelling agent, or the gelling agent and resin, aggregate to form strong aggregated particles, and the gaps through which the electrolyte can penetrate are particularly small.

[0094] Since the loss factor of the first layer 31 is also affected by the type of material contained in the first layer 31, the second loss factor ratio, which is the ratio of the second loss factor to the fourth loss factor calculated by the following equation (3), is used as an indicator. (Ratio of second loss factor) = (Second loss factor) / (Fourth loss factor) ... (3) Furthermore, by setting the second loss factor ratio to less than 5.5, the gelling agent and the gelling agent and resin aggregate, forming strong aggregated particles, which significantly reduces the gaps through which the electrolyte can penetrate. Therefore, even when applied to a battery, the first layer is prevented from absorbing the electrolyte and swelling, thus preventing a decrease in adhesion to the conductor.

[0095] The lower limit of the second loss factor ratio is not particularly limited, but one way to reduce the second loss factor ratio is to increase the amount of gelling agent added. However, if the amount of gelling agent added is increased, the gelling agent may precipitate in the first layer 31. For this reason, the second loss factor ratio can be set to, for example, 0.2 or higher.

[0096] The second loss factor ratio may be, for example, 0.2 or more and less than 5.5, or 0.2 or more and 5.0 or less. (3-1-2) 2nd layer, 3rd layer The second layer 32 and the third layer 33 may also contain resin, and, if necessary, gelling agents and additives. Since the resin, gelling agent, and additives described for the first layer 31 can be used, a further explanation is omitted.

[0097] The first layer 31, the second layer 32, and the third layer 33 may have the same composition or different compositions. When functional separation is performed between the first layer 31, the second layer 32, and the third layer 33, for example, the second layer 32 can be used as a heat-resistant layer.

[0098] For this reason, the second layer 32 may be crosslinked. Crosslinking the second layer 32 makes the insulating resin film less susceptible to crushing when the lead 13 is heat-pressed onto the outer casing 11, thereby increasing its mechanical strength.

[0099] The second layer 32 may have a degree of crosslinking equal to or greater than that of the first layer 31. For this reason, the proportion of crosslinking agent contained in the second layer 32 and the degree of ionizing radiation irradiation during crosslinking can be selected. For the third layer 33, for example, the composition and degree of crosslinking can be selected to improve adhesion with the outer casing 11. (3-2) Thickness of each layer The thicknesses T31 of the first layer 31, T32 of the second layer 32, and T33 of the third layer 33 may be the same or different. The thicknesses T31 of the first layer 31, T32 of the second layer 32, and T33 of the third layer 33 may each be, for example, between 30 μm and 200 μm.

[0100] Here, we have described the cases in which the insulating resin film 15 includes a first layer 31 and a second layer 32, and the cases in which it includes a first layer 31, a second layer 32, and a third layer 33. However, the number of layers in the insulating resin film 15 is not limited to two or three layers, and may be four or more layers. (4) Method for manufacturing insulating resin film for leads The method for manufacturing the insulating resin film 15 of this embodiment is not particularly limited. The method for manufacturing the insulating resin film of this embodiment may include, for example, a layer formation step and a lamination step. The method for manufacturing the insulating resin film of this embodiment may also include an electron beam irradiation step or the like, as needed.

[0101] The following describes each step. (4-1) Layer formation process In the layer formation process, each layer of the insulating resin film 15, namely at least the first layer 31 and the second layer 32, can be formed. If the insulating resin film to be manufactured has three or more layers, the layer formation process can also form layers other than the first layer 31 and the second layer 32, such as the third layer 33.

[0102] The specific method for forming each layer of the insulating resin film 15 is not particularly limited, but each layer can be formed by kneading the resin, gelling agent, additives, etc. contained in each layer and then extruding it.

[0103] Since the first layer 31 can contain, for example, a resin and a gelling agent, when forming the first layer 31 in the layer formation process, the first layer 31 can be formed by mixing the resin, the gelling agent, and additives such as a crosslinking agent as needed, and then extruding the mixture. (4-2) Bonding process In the lamination process, each layer of the insulating resin film 15 obtained in the layer formation process can be laminated and bonded together by heat pressing or the like. Specifically, in the lamination process, for example, the second layer 32 can be laminated onto the first layer 31 and then bonded together.

[0104] As shown in Figure 4A, the first layer 31 may have a first surface 400 and a second surface 401 located opposite the first surface 400. In the structure shown in Figure 4A, the second layer 32 can be laminated onto the second surface 401 of the first layer 31, and the first layer 31 and the second layer 32 can be bonded together. If the insulating resin film 15 has a third layer 33 as shown in Figure 4B, the third layer 33 may be further bonded to the first layer 31 and the second layer 32 during the bonding process. (4-3) Electron beam irradiation process In the electron beam irradiation process, each layer can be crosslinked by irradiating it with an electron beam.

[0105] The timing of the electron beam irradiation process is not particularly limited and may be performed on the layer to be crosslinked after the completion of the layer formation process and before the bonding process.

[0106] Alternatively, after the bonding process, an electron beam irradiation process may be performed on each of the laminated layers simultaneously.

[0107] When the electron beam irradiation process is performed after the layer formation process but before the bonding process, and crosslinking is not performed on some of the layers, the electron beam irradiation process does not need to be performed on the layers that are not crosslinked. When the electron beam irradiation process is performed on multiple layers, the electron beam irradiation conditions may differ for each layer.

[0108] The electron beam irradiation process can be performed multiple times, and may be performed after the layer formation process is completed, before the bonding process, and after the bonding process. After the layer formation process and before the bonding process, the electron beam irradiation process may be performed only on the second layer 32, for example. [Leads with insulating resin film] The insulating resin film-covered lead 13 of this embodiment may have a plate-shaped conductor 14 having a rectangular upper surface 141 and a lower surface 142, and an insulating resin film 15. The insulating resin film 15 includes a first insulating resin film 151 disposed on the upper surface 141 of the conductor 14, and a second insulating resin film 152 disposed on the lower surface 142 of the conductor 14.

[0109] The insulating resin film 15 is an insulating resin film for a lead according to one aspect of the present disclosure, and is laminated in the order of conductor 14, first layer 31, and second layer 32, for example, as shown in Figure 3. That is, the insulating resin film 15 can be arranged on the conductor 14 so that it is laminated in the order of first layer 31 and second layer 32, starting from a position close to the conductor 14.

[0110] In this embodiment, the lead with an insulating resin film has an insulating resin film 15 according to one aspect of the present disclosure heat-pressed onto the conductor 14.

[0111] According to one aspect of the present disclosure, when applied to a battery, the first layer 31 is prevented from absorbing the electrolyte and swelling, thereby preventing a decrease in adhesion to the conductor 14.

[0112] Therefore, according to the insulating resin film-equipped lead 13 of this embodiment, even when applied to a battery, it is possible to prevent the conductor 14 and the insulating resin film 15 from peeling off, thereby increasing durability.

[0113] The lead with insulating resin film of this embodiment has been described in "(2) Lead with insulating resin film" for leads, so the explanation will be omitted here. [Examples]

[0114] The present invention will be described below with specific examples, but it is not limited to these examples and includes equivalents and modifications within the scope that achieve the effects of the present invention. 1. Evaluation Method The insulating resin films prepared in each of the following experimental examples were evaluated as follows. (1) Loss factor ratio The loss coefficient of the first layer 31 was measured by varying the angular frequency from 0.01 rad / sec to 100 rad / sec while maintaining the temperature of the first layer 31 at 160°C.

[0115] The loss coefficient was measured using a dynamic viscoelasticity measuring device (model: DVA220, manufactured by IT Measurement Control Co., Ltd.). The first layer 31 of the film was measured in shear mode.

[0116] In Figure 6, under the "Loss Factor" column, the "First Loss Factor (ω=0.01)" column shows the first loss factor at an angular frequency of 0.01 rad / sec. The "Second Loss Factor (ω=0.1)" column shows the second loss factor at an angular frequency of 0.1 rad / sec. The "Third Loss Factor (ω=10)" column shows the third loss factor at an angular frequency of 10 rad / sec. The "Fourth Loss Factor (ω=100)" column shows the fourth loss factor at an angular frequency of 100 rad / sec.

[0117] Furthermore, in Figure 6, the "First Loss Factor Ratio (ω=0.01 / ω=10)" column shows the first loss factor ratio calculated using equation (2) described above. Similarly, the "Second Loss Factor Ratio (ω=0.1 / ω=100)" column shows the second loss factor ratio calculated using equation (3) described above.

[0118] Figure 5 also shows the relationship between the amount of gelling agent added and the first loss coefficient ratio, summarizing the results of the following experimental examples. (2) Peel test Using the insulating resin films prepared in each of the following experimental examples, we fabricated leads with insulating resin films as shown in Figures 2 and 3, and performed a 180° peel test on the insulating resin films.

[0119] For the conductor 14, an aluminum plate with a thickness of 0.4 mm was used.

[0120] The insulating resin film 15 has a length L15 of 20 mm along the Y axis, and extends 1 cm to the left and right of the conductor 14. In other words, in Figure 2, its length W15 along the X axis is 2 cm longer than the length W14 of the conductor 14 along the X axis.

[0121] Then, insulating resin films 15 were placed on the upper surface 141 and lower surface 142 of the conductor 14, respectively, and the insulating resin films 15 were heat-pressed onto the conductor 14 by heating at 150°C for 2 minutes while applying a pressure of 0.05 MPa.

[0122] The insulating resin film of the obtained insulating resin film-attached leads was immersed in a solution simulating an electrolyte for 7 days, and then a peel test was performed. The solution simulating the electrolyte was a mixed solution containing diethyl carbonate, ethyl carbonate, and dimethyl carbonate in a volume ratio of diethyl carbonate:ethyl carbonate:dimethyl carbonate = 1:1:1.

[0123] The peel test was conducted according to the method described in "10.4 Measurement of peel adhesive strength" and "10.4.1 Method 1: 180° peel adhesive strength to the test plate" of JIS Z 0237 (2022). The evaluation results are shown in the "Peel Test" column of Figure 6.

[0124] The insulating resin films prepared in each experimental example are described below. 2. Conditions for manufacturing insulating resin film The insulating resin films prepared in each experimental example are described below.

[0125] Experimental Example 1 is a comparative example, and Experimental Examples 2 through 7 are examples of actual cases. [Experimental Example 1] (1) Layer formation process (1-1) First layer formation process The first layer 31 was fabricated using the following procedure.

[0126] A first layer 31 in film shape was fabricated by kneading polypropylene resin, a thermoplastic resin, and extruding it. The loss factor and loss factor ratio were measured and calculated for the obtained first layer. (1-2) Second layer formation process The second layer 32 was fabricated using the following procedure.

[0127] A film was prepared by kneading polypropylene resin, a thermoplastic resin, with triallyl isocyanurate, a crosslinking agent, and then extruding the mixture. Triallyl isocyanurate was added in a ratio of 0.5 parts by mass per 100 parts by mass of polypropylene resin.

[0128] The second layer 32 was fabricated by crosslinking the film obtained after extrusion molding with an electron beam under the conditions of an acceleration voltage of 200 kV and an irradiation dose of 200 kGy. (2) Bonding process The first layer 31 obtained in the layer formation process and the second layer 32 were bonded together by heat and pressure to form the insulating resin film of Experimental Example 1.

[0129] The evaluation results are shown in Figure 6. [Experimental Examples 2 to 7] In the first layer formation process, a gelling agent was added to the polypropylene resin in the mass ratio shown in the gelling agent column of Figure 6, kneaded, and extruded to produce the first layer 31 in film shape. As the gelling agent, 1,3:2,4-di-O-benzylidene-D-sorbitol, a sorbitol-based gelling agent, was used.

[0130] Except for the points mentioned above, the insulating resin film was prepared under the same conditions as in Experimental Example 1. Note that if the gelling agent exceeds 5.0% by mass, the gelling agent will be unevenly distributed or precipitate within the first layer, so such experimental examples are not shown in Figure 6.

[0131] The evaluation results are shown in Figure 6.

[0132] As shown in Figure 6, in Experimental Examples 2 to 7, where the first layer contained a gelling agent, the peel test results were improved compared to Experimental Example 1, where the first layer did not contain a gelling agent. In other words, in Experimental Examples 2 to 7, it was confirmed that an insulating resin film for leads was obtained that, when applied to a battery, prevents a decrease in adhesion to the conductor due to absorption and swelling of the electrolyte.

[0133] Furthermore, as shown in Figure 5, the first loss coefficient ratio decreases as the amount of gelling agent added increases. This confirms that the gelling agent, or the gelling agent and resin, aggregate to form strong aggregated particles, thereby reducing the gaps through which the electrolyte and other substances can penetrate. [Explanation of symbols]

[0134] 10 batteries 11 Exterior 110 Seal part 111 1st resin layer 112 Metal layer 113 Second resin layer 12 Electrode Stack 13. Leads (leads with insulating resin film) 14 Conductors 141 Top surface 142 Bottom surface 14A End 15 Insulating resin film 151 First insulating resin film 152 Second insulating resin film 16 test specimens 21 sides 22 sides 23 sides 24 sides 25 First end area 26 Second end area L14 Length W14 Length L15 Length W15 Length 31 1st layer 32 2nd layer 33 3rd layer 400 Page 1 401 2nd page T31 Thickness T32 Thickness T33 Thickness XX axis YY axis ZZ axis

Claims

1. A first layer having a first surface and a second surface located opposite the first surface, The first layer comprises a second layer laminated on the second surface of the first layer, The first layer comprises a resin and a gelling agent, wherein the insulating resin film is for a lead.

2. The insulating resin film for leads according to claim 1, wherein the content ratio of the gelling agent to the resin in the first layer is 0.05% by mass or more and 5.0% by mass or less.

3. The insulating resin film for leads according to claim 1, wherein the content ratio of the gelling agent to the resin in the first layer is 0.2% by mass or more and 5.0% by mass or less.

4. The insulating resin film for leads according to claim 1, wherein the content ratio of the gelling agent to the resin in the first layer is 0.4% by mass or more and 5.0% by mass or less.

5. The insulating resin film for leads according to any one of claims 1 to 4, wherein the second layer is crosslinked.

6. The insulating resin film for leads according to any one of claims 1 to 4, wherein the gelling agent comprises one or more selected from natural polysaccharides, saturated aliphatic hydroxycarboxylic acids, metal soaps, amino acid derivatives, diamide derivatives, and sorbitol-based gelling agents.

7. The insulating resin film for leads according to any one of claims 1 to 4, wherein the resin comprises a polyolefin resin.

8. The loss factor at an angular frequency of 0.01 rad / sec is defined as the first loss factor, the loss factor at an angular frequency of 0.1 rad / sec as the second loss factor, the loss factor at an angular frequency of 10 rad / sec as the third loss factor, and the loss factor at an angular frequency of 100 rad / sec as the fourth loss factor. When the ratio of the first loss coefficient to the third loss coefficient is defined as the first loss coefficient ratio, The first layer is an insulating resin film for leads according to any one of claims 1 to 4, wherein the first loss coefficient ratio is less than 4.5 at 160°C.

9. The loss factor at an angular frequency of 0.01 rad / sec is defined as the first loss factor, the loss factor at an angular frequency of 0.1 rad / sec as the second loss factor, the loss factor at an angular frequency of 10 rad / sec as the third loss factor, and the loss factor at an angular frequency of 100 rad / sec as the fourth loss factor. When the ratio of the second loss coefficient to the fourth loss coefficient is defined as the second loss coefficient ratio, The first layer is an insulating resin film for leads according to any one of claims 1 to 4, wherein the second loss coefficient ratio is less than 5.5 at 160°C.

10. A plate-shaped conductor having a rectangular shape on its upper and lower surfaces, The conductor comprises a first insulating resin film disposed on the upper surface of the conductor and a second insulating resin film disposed on the lower surface of the conductor. The first insulating resin film and the second insulating resin film are insulating resin films for leads according to any one of claims 1 to 4, and the conductor, the first layer, and the second layer are laminated in that order to form an insulating resin film lead.

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