TWI658630B - Packaging materials, battery outer cases and batteries - Google Patents

Abstract

The packaging material 1 of the present invention is characterized in that it includes a heat-resistant resin layer 2 as an outer layer, a thermoplastic resin layer 3 as an inner layer, and a metal foil layer 4 disposed between the two layers; The plastic resin layer 3 includes at least a mixed resin layer formed of a resin composition, and the resin composition includes a first resin made of a polyolefin resin having a low melting point and a high flow, and a resin having a high melting point and a low flow. The second resin made of polyolefin resin. The packaging material of the present invention has good productivity, can reduce costs, and ensure sufficient sealing, and at the same time prevents the internal pressure and temperature of the battery case and the like formed by the packaging material from rising excessively, resulting in an increase in internal pressure caused by the inability to leak gas. Cracked packaging material.

Description

Packaging materials, battery outer cases and batteries

The present invention relates to a packaging material that can be suitably used as an exterior material for a battery such as a lithium ion battery.

In this specification, "MFR" refers to MFR (melt flow rate) measured under conditions of a temperature of 230 ° C and a load of 2.16 kg based on JIS K7210-1999.

In addition, in this specification, "melting point" means the melting peak temperature (melting point) measured using a differential scanning calorimeter at a heating rate of 10 ° C / min in accordance with the method specified in JIS K7121-1987 "Method for Measuring the Conversion Temperature of Plastics". ).

In the present invention, the meaning of "aluminum" includes aluminum and its alloys. The meaning of "metal" includes metal monomers and their alloys.

Lithium-ion batteries are widely used as power sources for, for example, notebook computers, video cameras, mobile phones, and electric vehicles. This lithium ion secondary battery is used by surrounding a battery body (a body including a positive electrode, a negative electrode, and an electrolyte) with a casing. It is known that the material for the casing (outer material) is, for example, an outer layer made of a heat-resistant resin film, an aluminum foil layer, and an inner layer made of a thermoplastic resin film.

However, lithium-ion batteries and the like tend to generate gas in the battery body during overcharging or overheating. Therefore, gas is gradually accumulated in the inner space covered by the exterior material, and the internal pressure inside the exterior material rises. situation. This excessive increase in internal pressure will cause the exterior material to rupture and there is a concern that the internal contents will be scattered. Therefore, a technique for preventing such an exterior material from being cracked has been proposed.

For example, Patent Document 1 describes an electric storage device with an explosion-proof function, which is an electrode laminate having a positive electrode and a negative electrode formed in a sheet shape laminated with a separator interposed therebetween, and the electrode laminate is accommodated in a metal together with an electrolytic solution. After laminating the inside of the container made of film, the metal composite film is heat-sealed along the outer periphery of the container, and the container is sealed and sealed with a heat-sealing portion, and the explosion-proof power storage device is attached to the container. , Which is provided with a drilling device comprising: a blade support for connecting and fixing the outer peripheral portion of the container in a sandwiched state; and a blade support supported by the blade support and disposed in the container at The blade element at a position closer to the center of the sealing portion; when the blade support body generates gas, the container deformed by expansion and expansion is moved to the outer peripheral direction of the container, and the blade element together with the blade support body The container is moved to cut the container, and becomes a power storage device with an explosion-proof function.

In addition, Patent Document 2 describes a power storage element including a power storage element body immersed in an electrolytic solution, an exterior body that seals the power storage element body, and a first gas release mechanism portion provided inside the exterior body, and The second gas release mechanism section provided outside the exterior body passes the gas from the internal space of the exterior body in which the power storage element body is located, and sequentially passes through each of the gas release mechanism sections, thereby allowing the gas to pass from the interior. The space is released to an external space, and each of the gas release mechanism sections is provided with a pressure adjustment device, which can prevent gas from entering the internal space from the external space, and a space is formed between the gas release mechanism sections. The buffer space of each of the gas release mechanism sections is individually partitioned.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-156404

[Patent Document 2] Japanese Patent Laid-Open No. 2012-156489

However, as in Patent Document 1, when a drilling device having a blade support and a blade element is installed, a new step of installing the drilling device must be performed, and there are problems that the manufacturing steps are complicated and productivity is reduced. In addition, a new component of a so-called drilling rig must be provided, which will increase costs.

In addition, as in Patent Document 2, when a safety valve mechanism (gas release mechanism section, etc.) is provided for leaking the gas generated inside the exterior body to the outside of the exterior body, a new step of installing the safety valve mechanism is required, and there are manufacturing steps Complex, less productive issues. In addition, a new component of a so-called safety valve mechanism must be provided, which will increase the cost accordingly.

In view of such a technical background, an object of the present invention is to provide a packaging material that has good productivity, can reduce costs, ensure sufficient sealing, and can prevent excessive pressure and temperature of a battery case or the like formed from the packaging material. When it rises, the internal gas cannot leak, and the packaging material is broken due to the increase in internal pressure; and the present invention also provides a battery, which can prevent the battery case from leaking when the internal pressure and temperature rise excessively, due to internal pressure The battery case ruptured due to pressure rise.

To achieve the foregoing object, the present invention provides the following means.

[1] A packaging material comprising a metal foil layer and a thermoplastic resin layer as an inner layer; and in the packaging material, the thermoplastic resin layer contains at least a resin composition The resin layer is mixed, and the resin composition contains a first resin made of a polyolefin resin having a low melting point and a high flow, and a second resin made of a polyolefin resin having a high melting point and a low flow.

[2] A packaging material characterized by comprising: a heat-resistant resin as an outer layer, a thermoplastic resin layer as an inner layer, and a metal foil layer disposed between the two layers; and in the packaging material, The thermoplastic resin layer includes at least a mixed resin layer formed of a resin composition, and the resin composition includes a first resin made of a polyolefin resin having a low melting point and high flow, and a resin having a high melting point and low The second resin made of flowing polyolefin resin.

[3] The packaging material as described in the above item 1 or 2, wherein the thermoplastic resin layer contains at least the mixed resin layer and a single resin layer, a laminated structure of two or more layers, and the mixed resin layer configuration The mixed resin layer, the single resin layer, and the single resin layer arranged between the mixed resin layer and the metal foil layer on the innermost side are made of a single polyolefin resin, and the layered structure of two or more layers.

[4] The packaging material according to any one of the preceding paragraphs 1 to 3, wherein the MFR of the first resin is 10 g / 10 min or more; and the MFR of the second resin is less than 10 g / 10 min.

[5] The packaging material according to any one of the preceding paragraphs 1 to 4, wherein the melting point of the first resin is 105 ° C or higher and less than 140 ° C, and the melting point of the second resin is 135 ° C or higher and less than 180 ° C. Range: The melting point of the second resin is 3 ° C or more higher than the melting point of the first resin.

[6] The packaging material according to any one of items 1 to 5, wherein the polyolefin resin is a polyethylene resin or a polypropylene resin.

[7] The packaging material according to any one of items 1 to 5, wherein the polyolefin resin is a propylene homopolymer or an ethylene-propylene copolymer.

[8] An outer casing for a battery, which is obtained by deep-drawing or bulging the packaging material according to any one of the preceding paragraphs 1 to 7.

[9] A battery, comprising: two sheets of the packaging material described in any one of the preceding paragraphs 1 to 7, and a battery main body portion; and the battery main body portion is disposed between the two sheets of the packaging material. In the aforementioned two sheets of packaging material, the peripheral edges of the individual inner layers are sealed to form a battery case, and the battery body is sealed inside the battery case.

[10] The battery as described in the above item 9, wherein when the temperature of the battery case rises to a range of 120 ° C to 160 ° C, a through-exhaust path communicating with the internal space of the battery case will be generated in the inner layer, and At the same time, a peeling gap is formed between the metal foil layer and the inner layer to communicate with the through exhaust path. The gas in the battery case leaks to the outside through the through exhaust path and the peeling gap, which can prevent the internal pressure from rising. Crack the battery case.

[11] The battery according to claim 9 or 10, wherein the metal foil layer and the thermoplastic resin layer are laminated and integrated through a second adhesive layer, and the second adhesive layer is formed by An adhesive layer formed by dry lamination with a melting point of 60 ° C to 100 ° C.

[12] The battery according to any one of the preceding paragraphs 9 to 11, wherein at least one of the two packaging materials is formed into a three-dimensional shape by deep drawing or inflation molding.

[13] The battery as described in the above item 9, wherein when the temperature of the battery case rises to a range of 120 ° C to 160 ° C, the heat-seal portion formed by the individual inner layers of the two sheets of packaging material will produce the foregoing The internal space of the battery case communicates with the outside and the inside and outside communicate with the exhaust path. The gas in the battery case leaks to the outside through the inside and outside communicating exhaust path, which can prevent the internal pressure from rising and rupture the battery case.

According to the inventions (packaging materials) of [1] and [2], the thermoplastic resin layer is composed of a mixed resin layer formed of a resin composition, and the resin composition contains: a low-melting and high-flow polymer For example, the first resin made of olefin resin and the second resin made of high-melting and low-flowing polyolefin resin, for example, when the battery is overheated, gas volume is generated in the battery body and the internal pressure rises. At the same time, the packaging material is increased. The temperature of the formed battery case excessively rises. At this time, in the mixed resin layer constituting the inner layer, the first resin having a low melting point and a high flow may be melted first because the second resin having a higher melting point and a low flow may be melted and flowed appropriately. The strength of the mixed resin layer is reduced, and the internal pressure of the mixed resin layer is destroyed, which creates a gap that communicates with the interior (through the exhaust path, the connection Venting, etc.), the gas inside the battery case can leak to the outside through this gap, which can prevent the battery case and other packaging materials made of the packaging material from breaking due to the increase in internal pressure.

In addition, since the gas is leaked to the outside, there is no need to newly add a structural unit (such as a well-known drilling device or a gas release mechanism unit), so the cost can be suppressed and the advantage of more compactness can be realized.

According to the invention of [3], since the thermoplastic resin layer (inner layer) includes at least the single mixed resin layer disposed at the innermost side and the single (one type) disposed between the mixed resin layer and the metal foil layer. A single resin layer made of a polyolefin resin, and a laminated structure of two or more layers, that is, a single resin layer made of a single polyolefin resin is arranged between the mixed resin layer and the metal foil layer, so it can fully ensure heat sealing The thickness of the entire thermoplastic resin layer (inner layer) ensures stable sealing and insulation.

According to the invention of [4], since the MFR of the first resin is 10 g / 10 min or more; and the MFR of the second resin is less than 10 g / 10 min, for example, the internal pressure and temperature of a battery case made of a packaging material, etc. When the temperature rises excessively, the mixed resin layer is completely destroyed by the internal pressure, and the gas inside the battery case is easily leaked to the outside, so that the packaging material can be prevented from being broken due to the increase in the internal pressure.

According to the invention of [5], the melting point of the first resin is 105 ° C to 140 ° C; the melting point of the second resin is in the range of 135 ° C to 180 ° C (of course, the melting point of the second resin is higher than the melting point of the first resin) High), when the internal pressure and temperature of the battery case made of packaging materials rise excessively, the mixed resin layer is completely destroyed by the internal pressure, so that the gas inside the battery case is likely to leak to the outside, which can sufficiently prevent the internal pressure from rising. The resulting packaging material was cracked. Furthermore, since the melting point of the second resin is higher than the melting point of the first resin by 3 ° C or more, it is constituted by the packaging material. When the internal pressure and temperature of the battery case and the like rise excessively, the mixed resin layer is more completely destroyed by the internal pressure, so that the gas inside the battery case is likely to leak to the outside, and the packaging material caused by the increase in internal pressure can be fully prevented. rupture.

According to the invention of [6], since the polyolefin resin is composed of a polyethylene resin or a polypropylene resin, it is possible to sufficiently prevent the packaging material from being broken due to an increase in internal pressure at a low cost.

According to the invention of [7], since the aforementioned polyolefin resin is a propylene homopolymer or an ethylene-propylene copolymer, when a high temperature is reached, the gas inside the battery case can be leaked to the outside more smoothly, which can be more fully prevented The packaging material is broken due to an increase in internal pressure.

According to the invention of [8] (battery outer case), when the battery is overheated, a gas volume is generated in the battery main body portion, and the internal pressure is excessively increased, and the temperature of the battery outer case (battery case) is excessively increased. In the mixed resin layer constituting the inner layer, the low-melting and high-flowing first resin and the higher-melting and low-flowing second resin first melt-flow, so the strength of the mixed resin layer can be appropriately reduced, and by the internal pressure When the mixed resin layer is broken, a gap (through the exhaust passage) communicating with the inside is generated, and the gas inside the battery case can leak to the outside through this gap, thereby preventing the battery case from being broken due to an increase in internal pressure.

According to the invention (battery) of [9] and [10], the two sheets of the packaging material arranged on the battery main body portion with each other, and the peripheral edge portions of the inner layer are sealed with each other by heat sealing to form a battery case. When the battery body is sealed inside the case, when the battery overheats, a gas volume will be generated in the battery body and the internal pressure will increase. At the same time, the temperature of the battery case will rise to the range of 120 ° C to 160 ° C. A through-exhaust path that communicates with the internal space of the battery case is generated, and a connection between the metal foil layer and the inner layer is generated. The peeling gap through the exhaust passage, and the gas in the battery case leaks to the outside through the aforementioned exhausting passage and the peeling gap, which can prevent the battery case from being broken due to the increase in the internal pressure of the battery case.

In addition, since the gas is leaked to the outside, there is no need to newly add a structural unit (such as a well-known drilling device or a gas release mechanism unit), so the cost can be suppressed and the advantages of more compact batteries can be realized.

According to the invention of [11], the second adhesive layer between the inner layer and the metal foil layer (adhesive layer having a melting point of 60 ° C to 100 ° C formed by the dry lamination method) can generate a peeling gap, so the gas passes through it. After the peeling gap is leaked to the outside, each of the adhesives spaced by the second adhesive layer can be quickly melted (adhered) by the heat to close the peeling gap, thereby sufficiently preventing the contents of the battery from flowing to the outside.

According to the invention of [12], at least one of the two packaging materials is formed into a three-dimensional shape by deep drawing molding or inflation molding. When the battery is overheated, a gas volume is generated in the battery body portion, and the internal pressure is increased. At the same time, when the temperature of the battery case is raised to a range of 120 ° C to 160 ° C, the curved or twisted portion formed by the foregoing molding or the vicinity thereof can easily generate the aforementioned through-exhaust path, thereby fully preventing the battery casing from being caused by internal conditions. When the pressure rises and the battery case breaks.

According to the invention of [13], when the temperature of the battery case rises to a range of 120 ° C to 160 ° C, the heat-sealed portion formed by the individual inner layers of the two sheets of the packaging material will rise due to the internal pressure of the mixed resin layer. Destruction, etc., results in an internal and external communication exhaust path where the internal space of the battery case communicates with the outside. The gas in the battery case leaks to the outside through the internal and external communication exhaust path, which can prevent the battery case from rising due to the internal pressure of the battery case. Rupture situation.

In addition, to make the gas leak to the outside, there is no need to add additional components (such as (Such as a drilling device or a gas release mechanism), which can reduce costs and realize the advantage of a more compact battery.

1‧‧‧Packaging material

2‧‧‧outer layer (heat-resistant resin layer)

3‧‧‧inner layer (thermoplastic resin layer)

4‧‧‧ metal foil layer

5‧‧‧The first adhesive layer

6‧‧‧The second adhesive layer

10‧‧‧ Battery

11‧‧‧ Battery case

12‧‧‧ Internal space

13‧‧‧ Corner

15‧‧‧Battery body

21‧‧‧through exhaust

22‧‧‧ peeling gap

25‧‧‧Internal and external communication exhaust

31‧‧‧ mixed resin layer (innermost layer)

32‧‧‧Single resin layer

Fig. 1 is a cross-sectional view showing an embodiment of a packaging material of the present invention.

Fig. 2 is a cross-sectional view showing an embodiment of the battery of the present invention.

[Fig. 3] A cross-sectional view showing a battery mode in a state in which the inner layer generates a through-exhaust path through an excessive rise in internal pressure and temperature, and is between the inner layer and the metal foil layer. Gas in the battery case that has a peeling gap leaks to the outside, thereby preventing a state of cracking due to an increase in internal pressure.

[Fig. 4] A cross-sectional view showing a battery mode in a state where the internal pressure and temperature are excessively increased, and a heat-sealed portion formed by each inner layer is connected to the inside of the battery case. The space communicates with the outside and inside and outside of the exhaust path, so that the gas in the battery case leaks to the outside through the inside and outside through the exhaust path, thereby preventing the state of rupture caused by the increase in internal pressure.

Fig. 5 is a sectional view showing another embodiment of the packaging material of the present invention.

Fig. 6 is a sectional view showing still another embodiment of the packaging material of the present invention.

FIG. 1 shows an embodiment of the packaging material 1 of the present invention. This packaging material is used as a battery exterior material. The packaging material 1 is laminated and integrated on the upper surface of the metal foil layer 4 through the first adhesive layer 5 and the heat-resistant resin layer (outer layer) 2, and is simultaneously applied to the gold The lower surface of the metal foil layer 4 is configured by laminating and integrating the second adhesive layer 6 and the thermoplastic resin layer (inner layer) 3.

The above-mentioned thermoplastic resin layer (inner layer) 3 has excellent chemical resistance even for highly corrosive electrolytes used in lithium ion batteries and the like, and is also responsible for imparting heat sealability to the packaging material 1 .

In the present invention, the thermoplastic resin layer (heat-sealing layer) 3 is configured to include at least a mixed resin layer 31 formed of a resin composition containing a low-melting point and high-flowing polyolefin resin. The first resin formed and the second resin made of a polyolefin resin having a high melting point and a low flow. In the mixed resin layer 31, the first resin and the second resin are melt-mixed. Since such a specific structure is adopted, for example, when the battery body is overheated, gas is generated in the battery main body and accumulated to increase the internal pressure, and at the same time, the temperature of the battery case 11 constituted by the packaging material 1 is excessively increased. In the mixed resin layer 31 constituting the inner layer 3, the first resin having a low melting point and high flow will melt the second resin having a higher melting point and low flow first, so the strength of the mixed resin layer 31 can be appropriately reduced. The mixed resin layer 31 is destroyed by the internal pressure, thereby generating a through-exhaust passage 21 in the inner layer 3 communicating with the inner space 12 of the battery case 11 and a peeling gap between the inner layer 3 and the metal foil layer 4 22. The gas inside the battery case 11 (the exterior material 1) can leak to the outside, so that the battery case 11 and the like made of the packaging material 1 can be prevented from being broken (the packaging material bursts) due to an increase in the internal pressure.

In the packaging material 1 shown in FIG. 1, the thermoplastic resin layer 3 is composed of the mixed resin layer 31 (single-layer structure). However, the present invention is not particularly limited to such a single-layer structure. The plastic resin layer 3 may include at least the aforementioned mixed resin layer 31 The resulting multi-layer structure. Among them, the thermoplastic resin layer (heat-sealing layer) 3 is preferably a single polyolefin containing at least the aforementioned mixed resin layer 31 disposed on the innermost side, the aforementioned mixed resin layer 31 and the metal foil layer 4. The structure of a single resin layer 32 made of resin and a laminated structure of two or more layers (see FIG. 5). A single resin layer made of a single polyolefin resin is arranged between the mixed resin layer 31 and the metal foil layer 4, so the thickness of the entire thermoplastic resin layer (inner layer) 3 after heat sealing can be sufficiently ensured. In order to ensure stable sealing and insulation.

Hereinafter, the resin etc. which comprise the said thermoplastic resin layer 3 are demonstrated.

The mixed resin layer 31 is formed of a resin composition containing a first resin made of a polyolefin resin and a second resin made of a polyolefin resin. Here, the melting point of the first resin is lower than that of the second resin, and the MFR is higher than that of the second resin. That is, the melting point of the second resin is higher than that of the first resin, and the MFR is lower than that of the first resin.

The first resin is preferably a polyolefin resin having an MFR of 10 g / 10 min or more, and the second resin is preferably a polyolefin resin having an MFR of less than 10 g / 10 min. At this time, it is possible to sufficiently prevent an increase in internal pressure and The resulting packaging material rupture.

The first resin is preferably a polyolefin resin having an MFR of 10 g / 10 min to 40 g / 10 min. When the MFR of the first resin is 40 g / 10 min or less, the mutual dispersibility of the first resin and the second resin can be improved, and the mixed resin layer 31 can have a good appearance.

The second resin uses an MFR of 0.5 g / 10 min or more. Polyolefin resins less than 10 g / 10 min are preferred. The MFR is 0.5 g / 10 min or more, and the first resin and the second resin can be sufficiently melt-mixed.

The first resin is a polyolefin resin having a melting point of 105 ° C to 140 ° C, and the second resin is a polyolefin resin having a melting point of 135 ° C to 180 ° C (Of course, at this time (The melting point of the second resin is higher than the melting point of the first resin). At this time, the packaging material can be prevented from being broken due to an increase in internal pressure. In addition, since the melting point of the second resin is 180 ° C. or lower, heat sealability can be improved.

The first resin is preferably a polyolefin resin having a melting point of 120 ° C or higher and less than 140 ° C. The melting point of the first resin is 120 ° C. or higher, which can improve the heat resistance of the thermoplastic resin layer 3.

The melting point of the second resin is preferably higher than the melting point of the first resin by 3 ° C or more. In this case, the packaging material can be sufficiently prevented from being broken due to an increase in internal pressure. The melting point of the second resin is more preferably 5 ° C or higher than the melting point of the first resin, and particularly preferably 10 ° C or higher.

Although the mixing ratio of the first resin and the second resin in the mixed resin layer 31 is not particularly limited, it is preferable to set the ratio of the first resin / the second resin to 2/8 to 8/2 (mass ratio). In this case, the mutual dispersibility of the first resin and the second resin can be improved, and the mixed resin layer 31 can have a good appearance. Among them, it is particularly preferable to set the first resin / second resin = 4/6 to 6/4 (mass ratio).

The polyolefin resin (kind) constituting the thermoplastic resin layer 3 (mixed resin layer 31, single resin layer 32, etc.) is not particularly limited, but examples thereof include polyethylene resins, polypropylene resins, and olefin copolymer resins. , Acid denaturation of polyethylene resin, polypropylene tree Acid denatured products of lipids, acid denatured products of olefin copolymer resins, and the like.

The MFR of the polyolefin resin can be adjusted, for example, by changing the addition amount of a chain transfer agent such as hydrogen or ethylene when producing a polyolefin resin.

The melting point of the polyolefin resin can be adjusted, for example, for polypropylene resins by changing the copolymerization ratio (including the copolymerization ratio of 0% by mass) of other olefin components such as ethylene and 1-butene with respect to propylene. The resin can be adjusted by changing the copolymerization ratio (including the copolymerization ratio of 0% by mass) of other olefin components such as 1-butene and 1-hexene to propylene.

When the resin composition (resin composition containing the first resin and the second resin) constituting the mixed resin layer 31 is obtained, the first resin and the second resin can be melt-mixed using various kneading machines in advance, and can be used for film molding A roller, a Henschel mixer, a metering feeder, etc. dry-laminate the spherical or powdered first resin and the second resin, and then supply the T-die molding machine to form a film while melting and mixing.

The thermoplastic resin layer 3 is preferably composed of an unstretched film. The resin film constituting the thermoplastic resin layer 3 can be formed by, for example, a T-die molding machine or an inflation molding machine.

The thickness of the thermoplastic resin layer 3 is preferably set to 20 μm to 80 μm . By setting it at 20 μm or more, it is possible to sufficiently prevent the occurrence of pinholes. By setting it at 80 μm or less, the amount of resin can be reduced and the cost can be reduced. Among them, the thickness of the thermoplastic resin layer 3 described above is particularly preferably set to 30 μm to 50 μm .

The heat-resistant resin layer (outer layer) 2 is an element mainly responsible for ensuring good moldability as an exterior material, that is, it is responsible for preventing the metal foil from being broken due to necking. Cracked role.

Although the heat-resistant resin layer (outer layer) 2 is not particularly limited, for example, a stretched polyamide film (stretched nylon film, etc.), or a stretched polyester film is preferably used. The heat-resistant resin layer (outer layer) 2 includes a biaxially stretched polyimide film (e.g., a nylon film), a biaxially stretched polybutylene terephthalate (PBT) film, and a biaxially stretched film. Polyethylene terephthalate (PET) film and biaxially stretched polyethylene naphthalate (PEN) film are particularly preferred. Although the nylon is not particularly limited, examples thereof include nylon 6, nylon 66, and nylon MXD. The heat-resistant resin layer 2 may be formed of a single layer (a single stretched film) or a plurality of layers (for example, a biaxially stretched PET film / biaxially stretched polyester film / polyamide film). Extending multiple layers of nylon film, etc.).

The heat-resistant resin layer 2 includes a biaxially stretched polyester film disposed on the outside and a biaxially stretched polyamide film disposed on the first adhesive layer 5 side. The plurality of layers are composed of good. Furthermore, the heat-resistant resin layer 2 includes a biaxially stretched polyethylene terephthalate film disposed on the outside and a biaxially stretched nylon film disposed on the first adhesive layer 5 side. The layer composition is better.

The thickness of the heat-resistant resin film layer 2 is preferably set to 12 μm to 50 μm.

The heat-resistant resin layer 2 and the aforementioned thermoplastic resin layer 3 may be a single layer or a plurality of layers.

The metal foil layer 4 is responsible for providing the packaging material 1 with gas barrier properties to prevent oxygen or moisture from entering. The thickness of the metal foil layer 4 is 20 μm to 120 μ m aluminum foil is preferred. The metal foil layer 4 is preferably one obtained by firing an aluminum foil containing 0.5% by mass to 2.0% by mass of iron and 0.03% by mass to 0.5% by mass of silicon dioxide.

The outer layer 2 and the inner layer 3 of the packaging material 1 are layers made of resin. Although these resin layers are extremely small, there is a possibility that light, oxygen, and liquid may enter from the outside of the casing, and may be inside. Possibility of penetration of contents (battery electrolyte, food, medicine, etc.). When these intruders reach the metal foil layer 4, a cause of corrosion of the metal foil layer 4 is formed. In the present invention, it is preferable to form a chemical conversion film on at least the surface of the metal foil and the thermoplastic resin layer 3 side. Among them, it is particularly preferable to use a constitution in which a chemical conversion film is formed on both sides of the metal foil. In this case, the corrosion resistance of the metal foil layer 4 can be sufficiently improved. In addition, a configuration in which the chemical conversion film is formed on only one side of the metal foil may be employed.

The chemical conversion film is a film formed by performing a chemical conversion treatment on the surface of the metal foil. For example, it can be formed by performing a chromate treatment on the metal foil and performing a non-chromium type chemical conversion treatment using a zirconium compound. For example, in the case of chromate treatment, an aqueous solution of the mixture of any one of 1) to 3) below may be applied to the surface of the metal foil subjected to degreasing treatment and then dried.

1) An aqueous solution containing a mixture of at least one compound selected from the group consisting of phosphoric acid, chromic acid, metal salts of fluorides and non-metal salts of fluorides, and mixtures thereof

2) A resin containing at least one selected from the group consisting of phosphoric acid, acrylic resin, Chitosan derivative resins, and phenol resin, and a group selected from chromic acid and chromium (III) salt At least one compound in water mixture

3) A resin containing at least one member selected from the group consisting of phosphoric acid, an acrylic resin, a chitosan derivative resin, and a phenol-based resin, and at least one member selected from the group consisting of chromic acid and a chromium (III) salt. An aqueous solution of a compound and at least one compound selected from the group consisting of a metal salt of a fluoride and a non-metal salt of a fluoride, and a mixture thereof.

In the aforementioned chemical conversion film, the chromium adhesion amount (one side) is preferably 0.1 mg / m ² to 50 mg / m ² , and 2 mg / m ² to 20 mg / m ² is particularly preferable. Such a chemical conversion film with a chromium adhesion amount can obtain a packaging material with high corrosion resistance.

The first adhesive layer 5 is not particularly limited, but examples thereof include a polyurethane-based adhesive layer, an acrylic ester adhesive layer, a polyester polyurethane resin adhesive layer, and the like.

Examples of the second adhesive layer 6 include an adhesive layer formed of maleic anhydride-denatured polyethylene and a maleic anhydride-denatured polypropylene.

The thermoplastic resin layer 3 or the heat-resistant resin layer 2 may contain an additive. These additives are not particularly limited, but examples thereof include anti-blocking agents (silicon dioxide, talc, kaolin, acrylic resin beads, etc.), lubricants (fatty acid amides, waxes, etc.), and antioxidants (hindered phenols, etc.) Wait.

In the packaging material 1 of the present invention, the heat-resistant resin layer 2 is not an essential constituent layer, and as shown in FIG. 6, a side of the metal foil layer 4 may be used with a second adhesive layer 6 interposed therebetween. A layered and integrated structure is formed with the thermoplastic resin resin layer (inner layer) 3.

FIG. 2 shows an embodiment of the battery of the present invention. The battery 10 of the present invention includes two sheets of the packaging material 1 of the present invention, and also includes a battery body portion 15. The battery body portion 15 includes a positive electrode, a negative electrode, and an electrolyte.

The packaging material 1A of at least one of the aforementioned two packaging materials 1 is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape by a forming (blowing molding, deep drawing molding, etc.) step, and the other packaging material 1B is not performed. It is formed into a flat shape (see FIG. 2).

The battery body portion 15 is disposed between the two sheets of packaging materials 1A and 1B, and the peripheral portions of the inner layers 3 and 3 of the two sheets of packaging materials 1A and 1B are hermetically sealed by heat sealing. The battery case 11 is formed, and the battery body portion 15 is sealed in the internal space 12 of the battery case 11 (see FIG. 2).

In the battery 10, when the battery body portion 15 is overheated, a gas volume is generated in the battery body portion 15 to increase the internal pressure, and at the same time the temperature of the battery case 11 is increased to a range of 120 ° C to 160 ° C, the forming step is performed on the inner layer 3 to The formed bent or twisted corner portion 13 or its vicinity can easily generate the aforementioned through-ventilation passage.

Therefore, in the battery 10, when the battery body 15 is overheated, a gas volume is generated in the battery body portion 15 to increase the internal pressure and increase the temperature of the battery case 11 to a range of 120 ° C to 160 ° C. Due to damage or the like, in the corner portion 13 of the inner layer 3 or its vicinity, a through-exhaust passage 21 communicating with the inner space 12 of the battery case 11 is generated, and at the same time, communication is made between the metal foil layer 4 and the inner layer 3 The peeling gap 22 penetrating through the exhaust passage 21 allows the gas in the battery case 11 to leak to the outside through the penetrating exhaust passage 21 and the peeling gap 22 to prevent the battery case 11 from being broken due to an increase in internal pressure. (See Figure 3).

Furthermore, after the gas leaks to the outside through the peeling gap 22, each of the adhesives separated by the second adhesive layer 6 can be quickly melted (adhered) by heat, and the peeling gap 22 can be closed to prevent the electrolyte. Outflow.

The second adhesive layer 6 is preferably an adhesive layer having a melting point of 60 ° C. to 100 ° C. formed by a dry lamination method. At this time, after the gas leaks to the outside through the peeling gap 22, each adhesive spaced by the second adhesive layer 6 can be more quickly melted by heat. (Next) By closing the peeling gap 22, the internal solution of the battery can be sufficiently prevented from flowing to the outside.

After the gas leaks to the outside in this way, the peeling gap 22 can be immediately closed by the second adhesive layer 6 (the isolated second adhesives are melted by the heat and close the peeling gap 22), thereby preventing the electrolyte from flowing out. Therefore, the battery 10 of the present invention can be said to be equipped with a safety valve mechanism.

In addition, FIG. 3 shows a state in which the lower right corner portion 13 of the four corner portions 13 of the battery case 11 penetrates the exhaust passage 21, but is not particularly limited to this type. For example, The corner portion 13 may generate the through-exhaust passage 21, or the upper right corner portion 13 or the lower-left corner 13 may generate the through-exhaust passage 21, or the through-exhaust passage 21 may be generated in other parts of the battery case 11.

In addition, FIG. 3 shows a type in which the second adhesive layer 6 remains on both the metal foil layer 4 and the inner layer 3 when the peeling gap 22 is formed, but it is not particularly limited to this type. For example, it may be A type in which most of the second adhesive layer 6 is adhered to the metal foil layer 4 side, or a type in which most of the second adhesive layer 6 is adhered to the inner layer 3 side may be used.

In addition to the mechanism shown in FIG. 3 (through the exhaust passage 21 and the separation gap 22) described above, the mechanism shown in FIG. 4 also performs the role of a safety valve that allows gas to leak to the outside. That is, in the battery 10, when the battery overheats, a gas volume is generated in the battery body portion 15 to increase the internal pressure, and at the same time the temperature of the battery case 11 is raised to a range of 120 ° C to 160 ° C, the two packages are packed In the heat-sealed portion formed by each of the inner layers 3 of the material 1, due to damage to the mixed resin layer 31, etc., the internal space 12 connecting the battery case 11 and the external inside and outside communicating with the exhaust path 25 are generated. Gas can be exhausted through internal and external communication The gas path 25 leaks to the outside and prevents the battery case 11 from being broken due to an increase in internal pressure (see FIG. 4).

Moreover, in the present invention, when the internal pressure of the battery case rises, the mechanism for leaking gas to the outside is mostly either the mechanism shown in FIG. 3 or the mechanism shown in FIG. 4, but the invention is not particularly limited. Restricted to those who are formed by such institutions. In any case, by using only the packaging material 1 of the present invention, it is possible to cause the mixed resin layer 31 to be destroyed by an increase in the internal pressure of the battery case, so that the gas in the battery case can be leaked to the outside safely.

[Example]

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to those examples.

[Raw material (resin for inner layer)]

"PP1" ... ethylene-propylene random copolymer resin (melting point: 160 ° C, MFR: 7.5g / 10min)

"PP2" ... ethylene-propylene random copolymer resin (melting point: 140 ° C, MFR: 7.5g / 10min)

"PP3" ... ethylene-propylene random copolymer resin (melting point: 130 ° C, MFR: 21g / 10min)

"PP4" ... ethylene-propylene random copolymer resin (melting point: 125 ° C, MFR: 23g / 10min)

"PP5" ... ethylene-propylene random copolymer resin (melting point: 135 ° C, MFR: 20g / 10min)

"PP6" ... ethylene-propylene random copolymer resin (melting point: 94 ° C, MFR: 20g / 10min)

"PE1" ... medium density polyethylene resin (melting point: 140 ° C, MFR: 4g / 10min)

"PE2" ... low density polyethylene resin (melting point: 110 ° C, MFR: 25g / 10min).

"PP7" ... ethylene-propylene random copolymer resin (melting point: 160 ° C, MFR: 3g / 10min)

"PP8" ... ethylene-propylene random copolymer resin (melting point: 150 ° C, MFR: 5g / 10min)

"PE3" ... ethylene-1-butene copolymer resin (linear low-density polyethylene resin) (melting point: 125 ° C, MFR: 6g / 10min).

The "MFR" refers to an MFR (melt flow rate) measuring device (trade name: MELT INDEXER) manufactured by Toyo Seiki Co., Ltd. based on JIS K7210-1999. The temperature is 230 ° C under a load of 2. MFR (melt flow rate) measured at 16 kg.

In addition, the above "melting point" refers to a temperature rise rate using a DSC (differential scanning calorimeter) (model DSC-60A) manufactured by Shimadzu Corporation based on JIS K7121-1987 "Method for Measuring the Conversion Temperature of Plastics". The melting peak temperature (melting point) obtained by measuring the obtained DSC curve at 10 ° C / min.

<Example 1>

50 mass parts of "PP3", 50 mass parts of "PP2", After 0.1 parts by mass of silicon dioxide and 0.1 part by mass of erucamide were dry-blended using a roller, the mixture was melt-mixed using an extruder to obtain a resin composition. This resin composition was extruded at a resin temperature of 230 ° C. by a T-shaped molding machine to obtain a film for an inner layer having a thickness of 40 μm.

On the other hand, a polyacrylic acid (acrylic resin), a compound of a chromium (III) salt, a phosphoric acid, water, and an alcohol are applied to both surfaces of a 40 μm-thick aluminum foil (A8079-O aluminum foil) 4 and then, It dried at 150 degreeC, and prepared the double-sided aluminum-plated foil which formed the chemical-film on both sides. The amount of chromium deposited on the formed film was 5 mg / m ^{2 on} one side.

Next, a two-liquid curable polyester polyurethane resin adhesive is applied to one surface of the aluminum foil 4 on which the two surfaces are formed into a film, and the first adhesive layer 5 is formed after drying, and the first adhesive layer is formed. The surface of 5 is bonded to a biaxially stretched 6-nylon film (outer layer) 2 with a thickness of 25 μm. At the same time, a two-liquid curing adhesive (acid-denatured polypropylene is used as the main agent) is coated on the other side of the aluminum foil 4 at the same time. Hexamethylene diisocyanate as a two-liquid curing type adhesive with a curing agent), after drying, a second adhesive layer 6 is formed, and the surface of the second adhesive layer 6 is bonded to the above-mentioned film for an inner layer having a thickness of 40 μm (Thermoplastic resin layer) 3. By leaving this laminated body in a 40 ° C. environment for 4 days (protected), a packaging material 1 having a structure shown in FIG. 1 can be obtained.

<Example 2>

Except for the resin composition (for the film for the inner layer), 50 parts by mass of the "PP3", 50 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were used. After dry mixing, the extruder was used to melt-mix and obtain a resin composition, and the rest were the same as in Example 1 to obtain a packaging material 1 having a structure shown in FIG. 1.

<Example 3>

Except for the resin composition (for the film for the inner layer), the above-mentioned "PP4" 70 parts by mass, 30 parts by mass of the above-mentioned "PP1", 0.1 parts by mass of silicon dioxide, and 0.1 parts by mass of erucamide erythramine, dry-mixed using a roller, and melt-mixed using an extruder to obtain a resin composition other than the resin composition Others are the same as in Example 1, and a packaging material 1 having the structure shown in FIG. 1 is obtained.

<Example 4>

Except for the resin composition (for the film for the inner layer), 50 parts by mass of the "PP5", 50 parts by mass of the "PP2", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were used. After dry mixing, the resin composition obtained by melt-mixing using an extruder was the same as in Example 1 to obtain a packaging material 1 having a structure shown in FIG. 1.

<Example 5>

Except for the resin composition (for the film for the inner layer), 60 parts by mass of the "PP4", 40 parts by mass of the "PP2", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were used. After dry mixing, the resin composition obtained by melt-mixing using an extruder was the same as in Example 1 to obtain a packaging material 1 having a structure shown in FIG. 1.

<Example 6>

Except for the resin composition (for the film for the inner layer), 30 parts by mass of the "PP4", 70 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were used. After dry mixing, the resin composition obtained by melt-mixing using an extruder was the same as in Example 1 to obtain a packaging material 1 having a structure shown in FIG. 1.

<Example 7>

Except for the resin composition (for the film for the inner layer), 80 parts by mass of the "PP5", 20 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were used. After dry mixing, the resin composition obtained by melt-mixing using an extruder was the same as in Example 1 to obtain a packaging material 1 having a structure shown in FIG. 1.

<Example 8>

Except for the resin composition (for the film for the inner layer), 70 parts by mass of the "PE2", 30 parts by mass of the "PE1", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were used. After dry mixing, the resin composition obtained by melt-mixing using an extruder was the same as in Example 1 to obtain a packaging material 1 having a structure shown in FIG. 1.

<Comparative example 1>

Except for the resin composition (for the film for the inner layer), 100 parts by mass of the above-mentioned "PP1", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucylamine were dry-blended using a roller, and then extruded using an extruder. The packaging material obtained was the same as in Example 1 except for the resin composition obtained by the melt-mixing.

<Comparative example 2>

Except for the resin composition (for the film for the inner layer), 100 parts by mass of the above-mentioned "PP2", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucylamine were dry-blended using a roller, and then extruded using an extruder. The packaging material obtained was the same as in Example 1 except for the resin composition obtained by the melt-mixing.

<Comparative example 3>

Except for the resin composition (for the film for the inner layer), 100 parts by mass of the above-mentioned "PP6", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucylamine were dry-blended using a roller, and then extruded using an extruder. The packaging material obtained was the same as in Example 1 except for the resin composition obtained by the melt-mixing.

<Example 9>

50 parts by mass of the "PP3", 50 parts by mass of the "PP2", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were mass-mixed using a drum, and then melt-mixed using an extruder to obtain Resin composition A (resin composition for mixed resin layer 31).

Then, 100 parts by mass of the above-mentioned "PP7", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucylamine were dry-blended using a roller, and then melt-mixed using an extruder to obtain a resin composition B (single A resin composition is used for the resin layer 32).

Next, the resin composition A and the resin composition B were extruded at a resin temperature of 230 ° C. using a co-extrusion multilayer T-die forming machine to obtain a combined resin layer 31 having a thickness of 30 μm and a single resin layer 32 having a thickness of 10 μm. The film 3 for an inner layer having a thickness of 40 μm.

On the other hand, a 40 μm- thick aluminum foil (A8079-O aluminum foil) 4 was coated with a compound containing polyacrylic acid (acrylic resin), a chromium (III) salt compound, phosphoric acid, water, and an alcohol. Then, it dried at 150 degreeC, and the aluminum foil which formed the chemical-film on both sides was prepared. The amount of chromium deposited on the formed film was 5 mg / m ² on one side.

Next, a two-liquid curable polyester polyurethane resin adhesive is applied to one side of the aluminum foil 4 on which the chemical conversion film is formed on both sides, and the first adhesive layer 5 is formed after drying, and the first adhesive layer is formed on the first adhesive layer. The surface of 5 is bonded to a biaxially stretched 6-nylon film (outer layer) 2 with a thickness of 25 μm. At the same time, a two-liquid hardening adhesive is applied to the other side of the aluminum foil 4 (with acid-denatured polypropylene as the main agent). Hexamethylene diisocyanate is a two-liquid curing type adhesive with a curing agent), and a second adhesive layer 6 is formed after drying. The surface of the second adhesive layer 6 is as thick as the above. The inner layer with a thickness of 40 μm is bonded to the surface on the single resin layer 32 side of the film 3. By leaving this laminated body in a 40 ° C. environment for 3 days (protecting), a packaging material 1 having a structure shown in FIG. 4 can be obtained.

<Example 10>

Except for the resin composition A (resin composition for the mixed resin layer 31), 50 parts by mass of the "PP3", 50 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 0.5 g of erucamide 0.1 The mass parts were dry-blended using a drum, and then melt-mixed using an extruder to obtain a resin composition. The rest were the same as in Example 9 to obtain a packaging material 1 having a structure shown in FIG. 4.

<Example 11>

Except for the resin composition A (resin composition for the mixed resin layer 31), 70 parts by mass of the "PP4", 30 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 1.1 g of erucamide 0.1 The mass parts were dry-blended using a drum, and then melt-mixed using an extruder to obtain a resin composition. The rest were the same as in Example 9 to obtain a packaging material 1 having a structure shown in FIG. 4.

<Example 12>

Except for the resin composition A (resin composition for the mixed resin layer 31), 50 parts by mass of the "PP5", 50 parts by mass of the "PP2", 0.1 part by mass of silicon dioxide, and 1.1 g of erucylamine The mass parts were dry-blended using a drum, and then melt-mixed using an extruder to obtain a resin composition. The rest were the same as in Example 9 to obtain a packaging material 1 having a structure shown in FIG. 4.

<Example 13>

In addition to resin composition A (resin composition for mixed resin layer 31), 60 parts by mass of the "PP4", 40 parts by mass of the "PP2", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide erythramine were dry-blended using a drum, and then melt-mixed using an extruder to obtain a resin. At the same time, the resin composition B (resin composition for a single resin layer 32) uses 100 parts by mass of the aforementioned "PP8", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide. After the drum was dry-blended, it was melt-mixed using an extruder to obtain a resin composition, and the rest were the same as in Example 9 to obtain a packaging material 1 having a structure shown in FIG. 4.

<Example 14>

Except for the resin composition A (resin composition for the mixed resin layer 31), 30 parts by mass of the "PP4", 70 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 1.1 g of erucylamine After mass-drying using a roller, the resin composition is obtained by melt-mixing using an extruder. Meanwhile, for the resin composition B (resin composition for a single resin layer 32), 100 parts by mass of the above-mentioned "PP8" is used. Silica oxide 0.1 parts by mass and erucamide 1.1 parts by mass were dry-blended using a roller and melt-mixed using an extruder to obtain a resin composition. The rest were the same as in Example 9 to obtain the results shown in FIG. 4组合 的 包装 材 1。 The packaging material 1.

<Example 15>

Except for the resin composition A (resin composition for the mixed resin layer 31), 80 parts by mass of the "PP5", 20 parts by mass of the "PP1", 0.1 part by mass of silicon dioxide, and 1.1 g of erucamide 0.1 After the mass parts are dry-mixed with a roller, they are melt-mixed using an extruder to obtain a resin composition. Meanwhile, for the resin composition B (resin composition for a single resin layer 32), 100 parts by mass of the above-mentioned "PE3" is used. 0.1 parts by mass of silicon oxide, 0.1 parts by mass of erucylamine was dry-blended using a drum, and melt-mixed using an extruder to obtain a resin composition. The rest were the same as in Example 9 to obtain a packaging material 1 having a structure shown in FIG. 4.

<Example 16>

Except for resin composition A (resin composition for mixed resin layer 31), 70 parts by mass of the above-mentioned "PE2", 30 parts by mass of the above-mentioned "PE1", 0.1 parts by mass of silicon dioxide, and erucamide 1.1 After the mass parts are dry-mixed with a roller, they are melt-mixed using an extruder to obtain a resin composition. Meanwhile, for the resin composition B (resin composition for a single resin layer 32), 100 parts by mass of the above-mentioned "PE3" is used. Silica oxide 0.1 parts by mass and erucamide 1.1 parts by mass were dry-blended using a roller and melt-mixed using an extruder to obtain a resin composition. The rest were the same as in Example 9 to obtain the results shown in FIG. 4组合 的 包装 材 1。 The packaging material 1.

<Comparative Example 4>

Except for the resin composition A, 100 parts by mass of the above-mentioned "PP1", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucylamine were dry-blended using a drum, and then melt-mixed using an extruder to obtain a resin. Except for the composition, everything was the same as in Example 9 to obtain a packaging material.

<Comparative example 5>

Except for the resin composition A, 100 parts by mass of the above-mentioned "PP2", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide were mass-blended using a drum, and then melt-mixed using an extruder to obtain a resin. Except for the composition, everything was the same as in Example 9 to obtain a packaging material.

<Comparative Example 6>

Except for the resin composition A, 100 parts by mass of the above-mentioned "PP6", 0.1 part by mass of silicon dioxide, and 0.1 part by mass of erucamide erythramine were dry-blended using a drum, and then melt-mixed using an extruder to obtain a resin. Except for the composition, everything was the same as in Example 9 to obtain a packaging material.

Each packaging material obtained above was evaluated based on the following evaluation method, and the results are shown in Tables 1 and 2.

<Measurement method of sealing strength>

The packaging material 1 was cut to obtain two test pieces in the form of a booklet having a width of 15 mm and a length of 200 mm. After the two test pieces mentioned above were brought into contact with each inner layer 3 and overlapped, a heat sealer (a width of the sealing strip 5 mm) was used at a temperature of 190 ° C and a sealing pressure of 0.1 MPa in about half of the area on one side in the longitudinal direction. Under heat seal. Next, one of the two test pieces was placed on the other end region (the end portion without heat seal) in the longitudinal direction of the test piece, and was clamped with a chuck of a tensile tester, and then left in a 130 ° C atmosphere for 1 After 2 minutes, the two test pieces sealed and bonded were measured in this 130 ° C environment based on JIS K7127-1999. The distance between the first chucks was 100 mm, the tensile speed was 300 mm / min, and 180 degrees was peeled off. 15mm width heat seal strength (N / 15mm width). With this, the heat seal strength is above 1.0 (N / 15mm width).

<Rupture prevention evaluation method>

For each example and each comparative example, two sheets of packaging materials were prepared, one of which was 1A, and was formed into a slightly cuboid shape by deep drawing (35mm in height × 55mm in width × 4mm in depth, with a flange) The three-dimensional shape of the other sheet of packaging material 1B is kept flat without being formed. The battery body portion (simulation) 15 is arranged between these two sheets of packaging material 1A and 1B, and then the battery body portion 15 mL of water was dripped on the top surface, and then the peripheral parts of the inner layers 3 and 3 of the two sheets of packaging materials 1A and 1B were heat-sealed (sealing strip width 5mm) at a temperature of 190 ° C and a sealing pressure of 0.1 MPa The battery case 11 is heat-sealed to obtain an internal space 12 of the battery case 11 and a battery body portion is sealed. 15 batteries (analog) 10 (see FIG. 2).

The obtained battery (simulated product) was placed in an oven at 150 ° C., and was left in this state for a maximum of 6 minutes. The situation of gas leakage or cracking in the oven was visually observed, and evaluation was performed based on the following judgment criteria.

(Judgment criteria)

"○" ... When 1 minute to 2 minutes passes after being placed in the oven, as shown in FIG. 3, a through-exhaust passage 21 is generated in the inner layer 3, and a peeling gap is generated between the inner layer 3 and the aluminum foil layer 4 at the same time. 22. The gas in the battery case 11 can leak to the outside and prevent it from being broken due to an increase in internal pressure.

"×" ... After being placed in the oven, 4 to 5 minutes erupted and burst.

"××" ... There is no rupture after 6 minutes after being placed in the oven (at this time, the internal pressure will rise and rupture).

As clearly shown in Tables 1 and 2, the packaging materials according to Examples 1 to 16 of the present invention can obtain heat sealing strength of an appropriate size and ensure sufficient sealing properties. In addition, when the battery enclosed in the packaging materials of Examples 1 to 16 of the present invention is used, when the internal pressure of the battery case is excessively increased and the temperature of the battery case is excessively increased, the gas in the battery case may leak to the outside (internal The gas can be leaked to the outside safely) to prevent the battery case from being damaged due to the excessive rise of the internal pressure.

On the other hand, the batteries packed in the packaging materials of Comparative Examples 1 and 4 that deviate from the scope of the first patent application scope of the present invention will not crack after 6 minutes, but the internal pressure will increase when the internal pressure further rises. The burst broke. In addition, the batteries enclosed in the packaging materials of Comparative Examples 2 and 5 that deviate from the scope of the first scope of the patent application of the present invention have excessive heat seal strength due to high temperature. Therefore, when the internal pressure of the battery case is excessively increased and at the same time, Battery case temperature rises excessively The battery case will burst and burst.

In addition, the packaging materials of Comparative Examples 3 and 6 which deviated from the scope of the first scope of the patent application of the present invention have a heat seal strength of less than 1.0 (N / 15mm width) at 130 ° C, so they cannot be sufficiently obtained. Heat seal strength.

In addition, when the state of the battery (the state after the internal pressure of the battery case was excessively increased and the gas was leaked) was observed with an electron microscope using the battery mounted on the packaging material of Example 1 with an electron microscope, each A peeling gap 22 is generated between the sealing portions of the inner layers 3 and the aluminum foil layer 4, and a slightly thick direction penetrating through the inner layer 3 (the sealing portion of each inner layer) is formed, and a penetrating exhaust gas communicating with the peeling gap 22 is formed. Road 21.

[Possibility of industrial use]

The packaging material of the present invention can be used as a battery exterior material such as a storage battery (such as a lithium ion storage battery), but it is not particularly limited to this application. Among them, when the internal pressure and temperature of the packaging material of the present invention rise excessively, the generated gas can leak to prevent the packaging material (heat-sealed packaging material) from rupturing due to the increase in internal pressure, so it can be used as a mobile phone. Exterior materials for batteries, exterior materials for automotive batteries.

The battery of the present invention can be used as a battery such as a storage battery (such as a lithium ion storage battery). Among them, when the internal pressure and temperature of the packaging material of the present invention are excessively increased, the generated gas can leak to prevent the battery case (which is formed by heat-sealing and bonding two packaging materials) from rupturing due to the increase of the internal pressure. It is preferably used as a battery for mobile phones and a battery for automobiles.

This application is accompanied by the priority claim of Japanese Patent Application No. 2014-52184 filed on March 14, 2014. It then forms part of this application.

The terms and descriptions used herein are used to explain the embodiments of the present invention, and the present invention is not limited thereto. Any equivalents in the characteristic matters disclosed and described in the present invention should not be excluded, and various modifications within the scope claimed by the present invention should also be understood as acceptable.

Claims (13)

A packaging material characterized in that it comprises a metal foil layer and a thermoplastic resin layer as an inner layer; and in the packaging material, the aforementioned thermoplastic resin layer contains at least a mixed resin layer formed of a resin composition The resin composition contains a first resin made of a polypropylene resin having a low melting point and high flow, and a second resin made of a polypropylene resin having a high melting point and low flow. A packaging material characterized by comprising: a heat-resistant resin as an outer layer, a thermoplastic resin layer as an inner layer, and a metal foil layer disposed between the two layers; and in the packaging material, the aforementioned thermoplasticity The resin layer contains at least a mixed resin layer formed of a resin composition, and the resin composition contains: a first resin made of a polypropylene resin having a low melting point and a high flow; and a polymer having a high melting point and a low flow. The second resin made of acrylic resin. The packaging material according to item 1 or 2 of the scope of patent application, wherein the aforementioned low melting point and high flowing polypropylene resin is a low melting point and high flowing ethylene-propylene random copolymer; and the aforementioned high melting point and low flowing The polypropylene resin is a high melting point and low flow ethylene-propylene random copolymer. The packaging material according to item 1 or 2 of the scope of patent application, wherein the thermoplastic resin layer includes at least two layers of a laminated structure of the mixed resin layer and a single resin layer, and the mixed resin layer is arranged at the most. The single resin layer on the inside is disposed between the mixed resin layer and the metal foil layer, and is made of a single polyolefin resin. The packaging material according to item 1 or 2 of the scope of patent application, wherein the MFR of the first resin is 10 g / 10 min or more; the MFR of the second resin is less than 10 g / 10 min. The packaging material according to item 1 or 2 of the scope of the patent application, wherein the melting point of the first resin is from 105 ° C to 140 ° C, and the melting point of the second resin is from 135 ° C to 180 ° C; The melting point of the second resin is 3 ° C or more higher than the melting point of the first resin. The packaging material according to item 1 or 2 of the patent application scope, wherein the mixing mass ratio of the first resin and the second resin in the mixed resin layer is the first resin / the second resin = 20/80 ~ 70/30 . An outer casing for a battery, which is characterized in that the packaging material described in any one of claims 1 to 7 is obtained by deep drawing or bulging. A battery, characterized in that it includes: two pieces of packaging material described in any one of the scope of claims 1 to 7 and a battery body portion; and the battery body portion is arranged on the two pieces of packaging material At the same time, the peripheral parts of the individual inner layers of the aforementioned two sheets of packaging materials are heat-sealed to form a battery case, and the battery body is sealed inside the battery case. The battery as described in item 9 of the scope of the patent application, wherein when the temperature of the battery case rises to a range of 120 ° C to 160 ° C, the inner layer generates a through exhaust path communicating with the internal space of the battery case, and at the same time A peeling gap is formed between the metal foil layer and the inner layer and communicates with the penetrating exhaust path. The gas in the battery case leaks to the outside through the penetrating exhaust path and the peeling gap, which can prevent the internal pressure from rising and cause The battery case is cracked. The battery as described in claim 9 or 10, wherein the metal foil layer and the thermoplastic resin layer are laminated and integrated through a second adhesive layer, and the second adhesive layer is borrowed. An adhesive layer having a melting point of 60 ° C to 100 ° C formed by a dry lamination method. The battery according to any one of claims 9 or 10, wherein at least one of the aforementioned two sheets of packaging material is formed into a three-dimensional shape by deep drawing or inflation molding. The battery described in item 9 of the scope of the patent application, wherein when the temperature of the battery case rises to a range of 120 ° C to 160 ° C, a heat-seal portion formed by the individual inner layers of the two sheets of packaging material will be generated. The internal space of the battery case communicates with the outside and the inside and outside communicate with the exhaust path, and the gas in the battery case leaks to the outside through the inside and outside communicating exhaust path, which can prevent the internal pressure from rising and rupture the battery case.