JP5211460B2 - Battery packaging material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a battery packaging material that exhibits stable sealing properties, moisture resistance, and moldability with the packaging material.

The lithium ion battery is also referred to as a lithium secondary battery, and includes a battery having a liquid, gel-like, and polymer-like electrolyte, and a positive electrode / negative electrode active material made of a polymer. In this lithium ion battery, the lithium atom (Li) in the lithium transition metal oxide, which is the positive electrode active material, is charged as lithium ion (Li ⁺ ) during charging and enters the carbon layer of the negative electrode (intercalation). This is a battery in which charge / discharge reaction proceeds when ions (Li ⁺ ) are separated from the carbon layer (deintercalation) and move to the positive electrode to become the original lithium compound. From the nickel-cadmium battery and the nickel-hydrogen battery The output voltage is high, the energy density is high, and the apparent discharge capacity is reduced by repeating shallow discharge and recharging, so that there is no so-called memory effect.

  The composition of the lithium ion battery is as follows: positive electrode current collector (aluminum, nickel) / positive electrode active material layer (polymeric positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / electrolyte layer (propylene carbonate) , Carbonate electrolytes such as ethylene carbonate, dimethyl carbonate, ethylene methyl carbonate, inorganic solid electrolytes composed of lithium salts, gel electrolytes, etc.) / Anode active material layers (lithium metals, alloys, carbon, electrolytes, polyacrylonitrile, etc.) Molecular negative electrode material) / negative electrode current collector (copper, nickel, stainless steel) and an outer package for packaging them. As the exterior body, conventionally, a metal can obtained by pressing a metal into a cylindrical shape or a rectangular parallelepiped shape has been used.

  However, in the conventional metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. For this reason, since the hardware side is designed in accordance with the battery, the size of the hardware using the battery is determined by the battery, and there is no degree of freedom in shape.

  Therefore, in recent years, there is a tendency to use an exterior body (hereinafter referred to as an exterior body) made of a laminated body having a high degree of freedom in shape. The material structure of the exterior body includes at least a base material layer as an outer layer, a barrier layer, a heat seal layer as an inner layer, and an adhesive layer that adheres the above layers, in view of necessary physical properties, workability, economy, and the like as a battery. Further, there is a pouch type in which a pouch is formed from the exterior body configured as described above and the lithium ion battery main body is accommodated, or an embossed type in which the exterior body is pressed to form a recess and the lithium ion battery main body is accommodated in the recess. Has been developed.

  FIG. 8A is a perspective view of a pouch-type lithium ion battery using the pillow-shaped exterior body 10, and FIG. 8B is a perspective view showing a state in which the lithium ion battery is disassembled. As shown in FIGS. 8A and 8B, the lithium ion battery 1 is composed of a lithium ion battery body 2 and an exterior body 10, and the lithium ion battery body 2 housed in the exterior body 10 is By sealing the periphery, moisture resistance is secured.

  FIG. 9 is a perspective view of an embossed type lithium ion battery in which the lithium ion battery main body 2 is hermetically housed using an exterior body 10 including a tray 10a and a sheet 10b in which an embossed portion is formed.

  The lithium ion battery body 2 includes a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode (none shown). And a gold electrode terminal 4 that is connected to a positive electrode and a negative electrode in the cell 3 and has a tip projecting outside the exterior body 10.

  FIG. 10 shows the structure of a male type 21 and female type 22 press machine showing molding in an embossed type. FIG. 10A is a perspective view of the outer package 10 before pressing, and FIG. 10B is a perspective view of the outer package formed into a concave shape after pressing. Here, in the case of the embossed type exterior body 10, as shown in FIG. 10A or FIG. 10B, it is necessary to form a recess for housing the lithium ion battery body by press molding or the like.

  In any of the above types, when the lithium ion battery main body is sealed with the packaging material, the metal terminal 4 connected to each of the positive electrode and the negative electrode of the lithium battery main body is protruded to the outside and the metal terminal 4 is It is necessary to seal by thermal bonding in a sandwiched state. For this purpose, the inner layer of the packaging material is heat-adhered and sealed with a heat-adhesive resin having good adhesion to the metal, for example, an acid-modified olefin resin graft-modified with an unsaturated carboxylic acid, or Using an ordinary olefin-based resin that is inferior in adhesiveness to metal for the inner layer, the metal terminal sealing adhesive film made of the above-mentioned acid-modified olefin resin having good adhesiveness to the metal is used as the metal terminal and the inner layer. Generally, a method of interposing between them and sealing them by thermal bonding is generally used.

  By the way, as described above, the layer structure of the laminate is composed of a base material layer, a barrier layer made of a metal foil such as aluminum, and an inner heat seal layer. A lithium hexafluorophosphate solution is used. Here, when water vapor enters from the outside of the outer package made of the laminate, this lithium hexafluorophosphate solution reacts with the water vapor to produce hydrofluoric acid, and this hydrofluoric acid is the inner layer of the laminate. And the adhesion between the metal foil and the inner layer is lowered to cause peeling.

  As a result, there is a problem of shortening the battery life. Therefore, the laminate used for the lithium battery needs to block water vapor entering from the outside air. For this reason, the inner layer side of the metal foil needs to be made of a material having less water vapor transmission, and the total thickness of the inner layer side of the metal foil is also surely sealed from the meaning of suppressing water vapor transmission from the end face as much as possible. It is designed to be thick enough to be able to.

  The method of laminating the metal foil and the inner layer is roughly classified into a dry lamination method using a known dry lamination adhesive such as polyester and a thermal lamination method performed without using an adhesive.

  When the adhesive layer is formed by the dry lamination method, the productivity is superior to that of the thermal lamination method. However, in press molding, delamination occurs between the aluminum and the base material layer at the side wall. In addition, in the portion where the lithium battery main body is housed in the exterior body and the periphery of the lithium battery body is heat sealed, the surface of the inner surface of the aluminum is eroded by the hydrofluoric acid, and delamination may occur. . On the other hand, thermal lamination is excellent in water vapor barrier properties and durability, but is inferior in productivity and expensive.

  In addition, when a laminated body laminated by any one of the thermal lamination method and the dry lamination method is used as a battery packaging material as shown in FIGS. 8 and 9, sufficient sealing strength cannot be obtained with a low temperature seal, In order to increase the strength, it was necessary to lengthen the sealing time. Therefore, when used as a packaging material for batteries, there is a problem that the productivity of lithium batteries is inferior.

  Further, after heat sealing, the resin is not sufficiently filled in the metal terminal sandwiching portion of the laminate, and sufficient sealing performance may not be ensured, and water vapor may enter from the periphery of the metal terminal to cause delamination of the laminate.

  Accordingly, in view of the above problems, the present invention provides a battery packaging material that is suitable for press molding and has excellent low-temperature sealing properties and hermetic sealing properties in a laminate laminated by a thermal lamination method and a dry lamination method. The purpose is to do.

  In order to achieve the above object, the first configuration of the present invention is that at least a base material layer that is an outermost layer, a barrier layer made of aluminum foil, a chemical conversion treatment layer, an adhesive layer, and a heat seal layer that is an innermost layer are sequentially laminated. In the battery packaging material, the heat seal layer has at least a first polypropylene layer and a second polypropylene layer, and the second polypropylene layer is disposed on the innermost layer side of the first polypropylene layer, and has a low melting point, A battery packaging material characterized by a high melt index.

  The battery packaging material of the second configuration of the present invention is characterized in that the first polypropylene layer is an unstretched polypropylene layer, and the second polypropylene layer is a melt-extruded polypropylene layer.

  The battery packaging material of the third configuration of the present invention is characterized in that the melt-extruded polypropylene layer has a melt index of 5 g / 10 min to 30 g / 10 min.

  The battery packaging material according to the fourth aspect of the present invention is characterized in that the melt-extruded polypropylene layer has a melting point of 120 ° C. or higher and 150 ° C. or lower.

  The battery packaging material of the fifth configuration of the present invention is characterized in that the unstretched polypropylene layer has a melting point of 140 ° C. or higher and 180 ° C. or lower.

  The battery packaging material according to the sixth aspect of the present invention is characterized in that the unstretched polypropylene layer includes an ethylene / propylene random copolymer layer.

  The battery packaging material of the seventh configuration of the present invention is characterized in that the base material layer surface is a stretched polyester layer or a polybutylene terephthalate layer.

  The battery packaging material of the eighth configuration of the present invention is characterized in that a coating layer made of a slip agent is provided on the surface of the base material layer.

  The battery packaging material according to a ninth configuration of the present invention is characterized in that the adhesive layer is made of an acid-modified polyolefin.

  According to the first configuration of the present invention, in the heat seal layer having at least the first polypropylene layer and the second polypropylene layer, the second polypropylene layer having a lower melting point and a higher melt index than the first polypropylene layer is arranged on the innermost layer side. Thus, when the heat seal layer is overlapped and the seal portion is heated and pressurized, the second polypropylene layer melts with a certain viscosity earlier than the first polypropylene layer and is extruded toward the inside of the exterior body. For this reason, after heat sealing, a uniform heat seal layer in which no resin pool is generated is formed in the vicinity of the boundary between the seal portion and the exterior body, and the deterioration of the seal strength over time can be suppressed. Therefore, the sealing performance inside the exterior body can be ensured for a longer period.

  According to the second configuration of the present invention, the heat seal temperature can be lowered while maintaining the seal strength by providing the polypropylene layer melt-extruded on the surface of the unstretched polypropylene layer. Thereby, the lithium battery main body can be efficiently hermetically sealed in the battery packaging material, and the productivity of the lithium battery can be improved.

  In addition, the melt-extruded polypropylene layer having high fluidity is melt-sealed during heat sealing so as to hermetically seal so as to cover the entire metal terminal sandwiched portion, and blocks external water vapor that permeates from the metal terminal sandwiched portion. The production of hydrofluoric acid due to the reaction between water and water vapor can be suppressed.

  According to the third configuration of the present invention, by increasing the melt index of the polypropylene layer melt-extruded on the surface of the unstretched polypropylene layer, which is a heat seal layer, to 5 g / 10 min or more and 30 g / 10 min or less, the seal strength can be increased. it can.

  According to the fourth configuration of the present invention, the sealing temperature is lowered while maintaining the sealing strength by setting the melting point of the polypropylene layer melt-extruded on the surface of the unstretched polypropylene layer, which is a heat seal layer, to 120 ° C. or more and 150 ° C. or less. be able to.

  According to the fifth configuration of the present invention, since the melting point of the unstretched polypropylene layer is 140 ° C. or higher and 180 ° C. or lower, abnormal temperature rise occurs inside the exterior body due to overcharge or the like, and the metal terminals and electrodes inside the exterior body Even when the current collector generates heat and the melt-extruded polypropylene layer that is the innermost layer melts, the unstretched polypropylene layer does not melt, and the metal terminal, electrode, current collector and metal foil layer are in contact with each other. prevent. Thereby, generation | occurrence | production of an internal short circuit can be suppressed.

  According to the sixth configuration of the present invention, the heat seal portion of the outer package may be folded to secure a storage space for the lithium ion battery, but the unstretched polypropylene layer includes an ethylene / propylene random copolymer layer having excellent toughness. Thereby, generation | occurrence | production of the crack in the said bending part can be prevented. Thereby, it can prevent that the electrolyte inside an exterior body contacts a metal foil layer from the cracked part, and can ensure the insulation of an exterior body.

  According to the seventh configuration of the present invention, by using a stretched polyester or polybutylene terephthalate film on the surface of the base material layer, when the electrolyte or acid adheres to the surface of the exterior body, it prevents whitening of the exterior body surface and deterioration of insulation. be able to.

  According to the eighth configuration of the present invention, by applying and coating the slip agent on the surface of the base material layer, the slipperiness between the base material layer surface and the mold is ensured at the time of embossing, and stable press molding is performed. be able to.

  According to the ninth configuration of the present invention, by using an acid-modified polyolefin layer as an adhesive layer, a laminate having excellent water vapor barrier properties, electrolytic solution resistance, corrosion resistance, etc. can be produced by a thermal lamination method. it can.

  The present invention provides a packaging material for a lithium ion battery, which is excellent in hermetic barrier properties, electrolytic solution resistance, corrosion resistance, hermetic sealing properties, low temperature sealing properties, etc. in a laminate laminated by a thermal lamination method and a dry lamination method. It is. The exterior body will be described in more detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 8, FIG. 9, FIG. 10 of a prior art example, and description is abbreviate | omitted.

  First, the material etc. which comprise each layer of the packaging material for batteries concerning this invention laminated | stacked using the thermal lamination method are demonstrated with reference to FIG. The outer package 10 according to the present invention has a base material layer 12 as an outermost layer, a heat seal layer 14 as an innermost layer, and an aluminum foil layer 13 therebetween.

  The aluminum foil layer 13 and the heat seal layer 14 are laminated by firmly bonding the chemical conversion treatment layer 13a applied to the aluminum foil surface and the acid-modified polyolefin layer 8 (adhesive layer). Moreover, the base material layer 12 and the chemically treated aluminum foil layer 13 are bonded by the second adhesive layer 15 by a dry laminating method. Further, the surface of the base material layer 12 is coated with a slip agent to form a slip layer 11, and the heat seal layer 14 is composed of an unstretched polypropylene layer 16 and a polypropylene layer 9 melt-extruded on the surface thereof.

  At this time, by providing the chemical conversion treatment layer 13a on the surface of the metal foil 13 on the acid-modified polyolefin layer 8 side, the interlayer adhesion strength is further stabilized.

  Next, materials and the like constituting each layer of the battery packaging material according to the present invention laminated using the dry lamination method will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 1, and description is abbreviate | omitted. The exterior body 10 according to the present invention also has a base material layer 12 as an outermost layer, a heat seal layer 14 as an innermost layer, and a barrier layer 13 made of aluminum foil therebetween.

  The aluminum foil layer 13 and the heat seal layer 14 are firmly bonded by a dry laminating method using a chemical conversion treatment layer 13a and a fluorine-based resin layer 26 (adhesive layer) applied on the surface of the aluminum foil 13, and are laminated. Moreover, the base material layer 12 and the chemically treated aluminum foil layer 13 are bonded by the second adhesive layer 15 by a dry laminating method. The surface of the base material layer 12 is coated with a slip agent to form a slip layer 11. In the heat seal layer 14, the polypropylene layer 9 melt-extruded on the surface of the unstretched polypropylene layer 16 is additionally processed.

  At this time, the chemical conversion treatment layer 13b formed when laminating by the dry lamination method is formed with a chemical conversion treatment solution containing an aminated phenol polymer, a trivalent chromium compound, a phosphorus compound, and a carbodiimide. Thereby, the adhesive strength between the aluminum foil 13 and the heat seal layer 14 is increased, and the aluminum foil 13 and the electrolyte become stable over time. In addition, the provision of the fluorine-based resin layer 26 in the adhesive layer also provides performance with excellent water vapor barrier properties.

  FIG. 3 is an enlarged cross-sectional view showing the configuration around the positive electrode tab of the lithium ion battery. Portions common to FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. Further, the slip layer 11, the chemical conversion layers 13a and 13b, the acid-modified polyolefin 8, the fluororesin layer 26, and the second adhesive layer 15 shown in FIGS. 1 and 2 are omitted for simplification. The outer package 10 has a laminated structure composed of a plurality of layers, and is heat-sealed in a state where the metal terminal 4 is sandwiched by the innermost melt-extruded polypropylene layer 9.

  Usually, when the heat seal layer 14 is sealed, it is necessary to apply heat and pressure near the melting point of the unstretched polypropylene layer 16 to the seal portion. However, by providing the melt-extruded polypropylene layer 9 on the surface of the unstretched polypropylene layer 16, heat sealing can be performed at a temperature lower than the melting point of the unstretched polypropylene layer 16.

  At this time, when a melt-extruded polypropylene layer 9 having a melt index of 5 g / 10 min to 30 g / 10 min and a melting point of 120 ° C. to 150 ° C. is used, sufficient sealing strength is secured. The sealing temperature can be lowered.

  Further, when the lithium ion battery main body is sealed in the outer package 10 and the metal terminal 4 of the battery main body is sandwiched in a state of protruding outward and hermetically sealed, the melt-extruded polypropylene layer 9 has high fluidity, so that the metal terminal The opening of the exterior body 10 is hermetically sealed so as to cover the entire sandwiched portion. Therefore, the external water vapor | steam which permeate | transmits from the said metal terminal clamping part can be interrupted | blocked, and the production | generation of hydrofluoric acid by reaction of electrolyte and water vapor | steam can be suppressed.

  Further, in this lithium ion battery, the temperature inside the outer package 10 rises due to overcharge or the like, and the metal terminal 4, the electrode (not shown), and the current collector (not shown) may generate heat. At this time, the sandwiched portion of the metal terminal 4 of the melt-extruded polypropylene layer 9 which is the innermost layer is melted, and as a result, the metal foil layer 13 in the outer package 10 and the metal terminal 4, the electrode and the current collector come into contact with each other and are short-circuited. May cause.

  However, if the melting point of the unstretched polypropylene layer 16 between the metal foil 13 and the melt-extruded polypropylene layer 9 is 140 ° C. or more and 180 ° C. or less, even when the melt-extruded polypropylene layer 9 is melted, it is not stretched. Since the polypropylene layer 16 has a high melting point, it does not melt easily. Therefore, it can prevent that the metal terminal 4, an electrode, a collector, and the metal foil 13 contact and short-circuit.

  4A is a cross-sectional view of a lithium ion battery 1 encapsulated using the battery packaging material according to the present invention, and FIGS. 4B and 4C are the vicinity of the inner edge of the seal portion of FIG. 4A. It is sectional drawing which expands and shows 10a. Here, FIG. 4 shows only the metal foil layer 13 and the heat seal layer 14, and the other layers are omitted for explanation. The heat seal layer 14 is composed of a second polypropylene layer 24 and a first polypropylene layer 25 disposed on the innermost layer side. The second polypropylene layer 24 is melt-extruded as described with reference to FIGS. The polypropylene layer 9 and the first polypropylene layer 25 correspond to the unstretched polypropylene layer 16.

  Generally, the heat seal layer 14 is melted by heat and pressure applied at the time of heat sealing, and is extruded to the inside of the outer package. However, when the heat seal layer 14 is composed of two or more films, the temporal sealing strength after heat sealing differs depending on the arrangement of each film. In other words, by placing a film having a lower melting point and a higher melt index than the other films on the innermost layer side, a stable shape in which the resin reservoir 25a that causes distortion or cutting is not formed in the vicinity 10a of the inner edge of the sealed portion after sealing. Can be sealed.

  FIG. 4B is a diagram illustrating the flow of the heat seal layer 14 when the second polypropylene layer 24 has a higher melting point than the first polypropylene layer 25 and a low melt index. In this case, since the first polypropylene layer 25 has a lower melting point and a higher melt index than the second polypropylene layer 24 at the time of heat sealing, the first polypropylene layer 25 tends to flow out to the inside of the exterior body. The second polypropylene layer 24 cannot follow the flow (see arrow in FIG. 4B). For this reason, the resin reservoir 25a is formed in the vicinity 10a of the seal portion inner edge, and the heat seal layer 14 is nonuniform in the periphery of the resin reservoir 25a. Accordingly, immediately after heat sealing, the resin reservoir 25a adheres in the heat seal layer 14 and apparently shows a certain heat seal strength, but the electrolyte penetrates into the peripheral portion of the resin reservoir 25a with time and the portion peels off. , The sealing strength decreases. Therefore, the deterioration of the sealing performance of the exterior body over time becomes a problem.

  FIG. 4C shows the flow of the heat seal layer 14 when the innermost second polypropylene layer 24 has a lower melting point than the first polypropylene layer 25 and a higher melt index. When the seal portion is heated and pressurized, the innermost second polypropylene layer 24 has a lower melting point and a higher melt index than the first polypropylene layer 25, so that it will flow along the first polypropylene layer 25 to the inside of the outer package. (See arrow in FIG. 4 (c)).

  For this reason, after heat sealing, the uniform heat seal layer 14 is formed by the second polypropylene layer 24 in the vicinity 10a of the seal portion inner edge, and the resin pool 25a is not generated. Therefore, stable sealing performance is ensured in the vicinity of the inner edge 10a of the seal portion, and the deterioration of the seal strength with time is prevented as compared with the heat seal layer 14 in which the resin reservoir 25a shown in FIG. 4B is formed. Can do.

  Fig.5 (a) is a schematic perspective view which shows an example of the press work of the exterior body 10 which concerns on this invention. 21 is a male type, 10 is an outer package before pressing, and 22 is a female type. The exterior body 10 before pressing faces the surface on which the slip layer 11 is provided on the female die 22 side, and presses the surface of the heat seal layer 14 on which the polypropylene layer 9 is provided with the male die 21.

  FIG. 5B is a cross-sectional view showing the force acting on the exterior body 10 when the exterior body 10 is pressed. When pressed into a concave shape, as the depth of the side wall portion 22a of the female die 22 increases, the slipperiness between the surface of the base material layer 12 and the inner surface of the female die 22 becomes important. When a downward press is applied to the exterior body 10, a downward force x (arrow) due to the male die 21 acts on the heat seal layer 14 in the side wall portion 22 a, whereas an upward force due to friction acts on the base material layer 12. y (arrow) works. Therefore, a shearing force parallel to the interlayer adhesion surface of the outer package 10 acts on the outer package 10, and the work exerted on the outer package 10 by the shear force increases as the depth of the side wall portion 22a of the female die 22 increases. Causes delamination of the laminated structure or cracking of the barrier layer. Therefore, the slipperiness between the female die 22 and the base material layer 12 becomes important.

  On the other hand, when the slipperiness between the male mold 21 and the heat seal layer 14 is insufficient, the heat seal layer 14 is dragged to the male mold 21 during pressing, and the heat seal layer 14 may be wrinkled or torn. is there.

  Therefore, it is conceivable to coat the surface of the heat seal layer 14 with a slip agent in order to reduce the dynamic friction coefficient between the heat seal layer 14 and the male mold 21. However, in the exterior body 10 according to the present invention, the polypropylene layer 9 has a certain slip property. For this reason, it is not necessary to newly coat a slip agent on the heat seal layer, and the embossing can be performed stably.

  6A is a schematic perspective view showing the lithium ion battery 1, and FIG. 6B is a schematic perspective view showing the lithium ion battery 1 housed in a plastic case 19 indicated by a dotted line.

  After encapsulating the lithium ion battery body in the embossed outer package 10, the peripheral edge 10b is hermetically sealed to complete the lithium ion battery 1. However, when the lithium ion battery 1 is actually used, It is weak to impact and may cause cracking due to small scratches.

  Therefore, the lithium ion battery 1 is often stored and used in a plastic case 19. For example, when it is used for a mobile phone or the like, it is stored in a plastic case because it receives an impact when dropped.

  Here, in order to reduce the size of the lithium ion battery 1, it is necessary to fold the outer periphery seal portion 10 b of the lithium ion battery 1 and store it in the plastic case 19. FIG. 6C is a cross-sectional view of the lithium ion battery 1 accommodated in the plastic case 19 as viewed from the direction of the arrow x.

  In the bent portion 10c, which is the fold of the peripheral seal portion 10b, the heat seal layer is once melted at the time of heat sealing and then crystallized, so that cracking is likely to occur at the time of bending.

  Moreover, the electrolyte inside the outer package 10 may come into contact with the metal foil layer 13 due to this cracking, and the metal foil layer 13 may be energized. At this time, the output of the lithium ion battery is significantly reduced or the function of the battery is lost.

  However, when the unstretched polypropylene layer 16 is made of an ethylene / propylene random copolymer layer having excellent toughness, cracking of the unstretched polypropylene layer 16 can be prevented and the insulation of the outer package 10 can be ensured.

  Next, each layer of the exterior body 10 shown in FIGS. 1 and 2 will be specifically described. In addition, description is unified about the common slip layer 11, the base material layer 12, the barrier layer 13, and the heat seal layer 14 which concern on the exterior body laminated | stacked by the sea lantern lamination method and the dry lamination method. The base material layer 12 needs to have a spreadability that can withstand a press during embossing. Generally, it consists of a stretched polyester or nylon film. At this time, examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. Examples of nylon include polyamide resin, that is, nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like.

The base material layer 12 may be laminated with films of different materials in addition to the polyester film or nylon film in order to improve pinhole resistance and insulation when used as a battery outer package. . When making the base material layer 12 into a laminated body, a base material layer contains at least 1 resin layer of 2 or more layers, and the thickness of each layer is 6 micrometers or more, Preferably, it is 12-25 micrometers. Examples of laminating the base material layer include the following 1) to 7) although not shown.
1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched polyethylene terephthalate Mechanical suitability of packaging materials (stability of conveyance in packaging machines and processing machines), surface protection (heat resistance, electrolyte resistance) When making the exterior body for a lithium ion battery as an embossed type as a secondary process, the base material layer is formed for the purpose of reducing the frictional resistance between the mold and the base material layer during embossing or when an electrolytic solution adheres. In order to protect, it is preferable that the base material layer is multilayered, and an acid polyolefin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, and a blended material layer thereof are provided on the surface of the base material layer.
For example,
3) Fluorine resin / stretched polyethylene terephthalate (Fluorine resin is a film or formed by drying after liquid coating)
4) Silicone resin / stretched polyethylene terephthalate (silicone resin is a film or formed by drying after liquid coating)
5) Fluorine-based resin / stretched polyethylene terephthalate / stretched nylon 6) Silicone-based resin / stretched polyethylene terephthalate / stretched nylon 7) Acrylic resin / stretched nylon (Acrylic resin is film-like or cured after drying by liquid coating)

  The same effect can be obtained when stretched polyester, polybutylene terephthalate, or polyethylene naphthalate is used in place of the stretched polyethylene terephthalate.

  Here, the base material layer 12 is bonded to the metal foil layer 13 by the second adhesive layer 15 using a dry laminating method.

  Next, the barrier layer 13 will be described. The barrier layer 13 is a layer for preventing water vapor from entering the inside of the lithium ion battery from the outside, stabilizing the pinhole and processability (pouching, embossing formability) of the barrier layer alone, and being resistant to resistance. In order to have a pinhole, a metal such as aluminum or nickel having a thickness of 15 μm or more, or a film on which an inorganic compound such as silicon oxide or alumina is vapor-deposited may be mentioned. The barrier layer 13 preferably has a thickness of 20 ˜80 μm aluminum.

  In order to further improve the generation of pinholes and make the outer body type of the lithium ion battery an embossed type, in order to prevent the occurrence of cracks in the embossing molding, the material of the aluminum used as the barrier layer 13 is: By making the iron content 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight, the aluminum has good extensibility compared with aluminum not containing iron, and the exterior The generation of pinholes due to bending as a body is reduced, and the side wall can be easily formed when the embossed type exterior body is molded. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement of embossing formability are not observed, and the iron content of the aluminum exceeds 9.0% by weight. In this case, the flexibility as aluminum is hindered, and the bag-making property as an exterior body is deteriorated.

  In addition, aluminum produced by cold rolling changes its flexibility, waist strength and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in the present invention is harder than the non-annealed hard-treated product. Aluminum which tends to be soft with some or complete annealing is preferred. The degree of flexibility, waist strength, and hardness of aluminum, that is, the conditions for annealing, may be appropriately selected in accordance with processability (pouching, embossing). For example, in order to prevent wrinkles and pinholes during emboss molding, soft aluminum annealed according to the degree of molding can be used.

  Moreover, the adhesive strength with the adhesive 15 improves by performing the chemical conversion treatment 13a on the front and back surfaces of the aluminum that is the barrier layer 13.

  Next, the chemical conversion treatment layer will be described. The chemical conversion treatment layer 13a provided when laminating by the thermal lamination method is formed on at least the surface of the aluminum foil 13 on the heat seal layer 14 side. The chemical conversion treatment layer 13a can stably adhere the acid-modified polyolefin layer 8 and the aluminum foil 13 and prevent delamination of the aluminum foil 13 and the heat seal layer 14. It also has the function of preventing aluminum corrosion.

  Specifically, by preventing the delamination between the aluminum foil layer 13 and the heat seal layer 14 during embossing by forming an acid-resistant film such as phosphate, chromate, fluoride, triazine thiol compound, etc. The hydrogen fluoride produced by the reaction between the electrolyte and the water vapor of the lithium ion battery prevents the aluminum surface from being dissolved and corroded, especially the aluminum oxide present on the aluminum surface from being dissolved and corroded. Adhesion (wetting) can be improved.

  The chemical conversion treatment layer 13a is formed by chromium conversion treatment such as chromic chromate treatment, phosphoric acid chromate treatment, coating type chromate treatment, or non-chromium (coating type) chemical conversion treatment such as zirconium, titanium, zinc phosphate, etc. Although it is formed on the surface of the foil 13, it is firmly bonded to the fluororesin 15, and a continuous process is possible and a water washing step is unnecessary and the processing cost can be reduced. It is most preferable to treat with a treatment solution containing a coating type chemical conversion treatment, particularly an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound.

  Further, the chemical conversion treatment layer 13b provided in the case of laminating by the dry lamination method is formed by treating with a treatment liquid containing carbodiimide (resin) in addition to the above aminated phenol polymer, trivalent chromium compound, and phosphorus compound. The adhesive strength between the foil (metal foil layer 13) and the fluororesin layer 26 can be further increased, and it can be stabilized over time with respect to the electrolytic solution.

First, the aminated phenol polymer will be described. A well-known thing can be widely used as an aminated phenol polymer, for example, it consists of a repeating unit represented by the following formula (Chemical Formula 1), (Chemical Formula 2), (Chemical Formula 3), and (Chemical Formula 4). Mention may be made of aminated phenol polymers. X in the formula represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ₁ and R ₂ represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group, and may be the same group or different groups.

In the following formulas (Chemical Formula 1) to (Chemical Formula 4), examples of the alkyl group represented by X, R ₁ and R ₂ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, and isobutyl. And a straight chain or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group. Examples of the hydroxyalkyl group represented by X, R ₁ and R ₂ include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, 3- C1-C4 straight or branched chain in which one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group is substituted An alkyl group can be mentioned. In the following formulas (Chemical Formula 1) to (Chemical Formula 4), X is preferably any one of a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group.

In addition, the aminated phenol polymer represented by the following formulas (Chemical Formula 1) and (Chemical Formula 3) has an amino acid content of about 80 mol% or less, preferably about 25 to about 55 mol% of repeating units. It is a modified phenol polymer. The number average molecular weight of the aminated phenol polymer is preferably about 500 to about 1 million, more preferably about 1000 to about 20,000. An aminated phenol polymer is produced, for example, by polycondensing a phenol compound or naphthol compound with formaldehyde to produce a polymer comprising repeating units represented by the following (Chemical Formula 1) to (Chemical Formula 3). It is produced by introducing a water-soluble functional group (—CH ₂ NR ₁ R ₂ ) into the coalescence using formaldehyde and an amine (R ₁ R ₂ NH). The aminated phenol polymer can be used singly or in combination of two or more.

Next, the trivalent chromium compound will be described. As the trivalent chromium compound, known compounds can be widely used. For example, chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, sulfuric acid Potassium chromium etc. can be mentioned, Preferably they are chromium nitrate and chromium fluoride.

  Next, a phosphorus compound is demonstrated. As a phosphorus compound, a well-known thing can be used widely, For example, condensed phosphoric acids, such as phosphoric acid and polyphosphoric acid, these salts, etc. can be mentioned. Here, as said salt, alkali metal salts, such as ammonium salt, sodium salt, potassium salt, can be mentioned, for example.

  Next, carbodiimide (resin) will be described. The carbodiimide (resin) is generally produced by a condensation reaction of aromatic or aliphatic diisocyanate in the presence or absence of a terminal blocking agent in the presence of a carbodiimidization catalyst and decarbonization. A polycarbodiimide represented by the formula (Chemical Formula 5) produced by a condensation reaction involving decarbonization in the presence or absence of an aliphatic diisocyanate and a terminal blocking agent in the presence of a carbodiimidization catalyst An aqueous carbodiimide resin represented by the formula (Chemical Formula 6) in which polyethylene glycol is added to the resin can be used. The carbodiimide (resin) has a number average molecular weight of 1200 to 2500, preferably 1800 to 2200, as measured by GPC.

(N is an integer of 1 or more)

(M, n, x, y are integers of 1 or more)

Moreover, as the chemical conversion treatment layer 13b formed using the treatment liquid containing the aminated phenol polymer, the trivalent chromium compound, the phosphorus compound, and the carbodiimide (resin), the aminated phenol polymer is about 1 m ^2. 1 to about 200 mg, trivalent chromium compound is about 0.5 to about 50 mg in terms of chromium, phosphorus compound is about 0.5 to about 50 mg in terms of phosphorus, and carbodiimide (resin) is about 0.5 to about 200 mg The aminated phenol polymer is about 5 to about 150 mg, the trivalent chromium compound is about 1.0 to about 40 mg in terms of chromium, and the phosphorus compound is about 1.0 to about in terms of phosphorus. More preferably, about 40 mg and carbodiimide (resin) are contained in a proportion of about 1.0 to about 150 mg. In this case, the drying temperature is 150 to 250 ° C., preferably 170 to 250 ° C., and the heat treatment (baking treatment) is appropriate.

  Moreover, as a formation method of a chemical conversion treatment layer, what is necessary is just to shape | mold the said process liquid, selecting well-known coating methods, such as a barcode method, a roll coat method, a gravure coat method, a dipping method. In addition, before forming the chemical conversion treatment layer, the surface of the aluminum foil 13 is preliminarily treated by a known degreasing method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an acid activation method, The function of the chemical conversion treatment layer is preferably maximized and can be maintained for a long time.

  In addition, for each of the above layers, corona treatment, blast treatment, and oxidation treatment are appropriately performed for the purpose of improving and stabilizing film forming properties, lamination processing, and final product secondary processing (pouching, embossing). Surface activation treatment such as ozone treatment may be performed.

  Next, the acid-modified polyolefin layer 8 will be described. The acid-modified polyolefin layer 8 is a layer provided for bonding the metal foil layer 13 and the heat seal layer 14 which is the inner layer of the outer package 10 using a thermal lamination method, and is appropriately selected depending on the type of resin used for the heat seal layer 14. However, it is possible to use acid-modified polyolefin resin, polyolefin resin graft-modified with unsaturated carboxylic acid, copolymer of ethylene or propylene and acrylic acid, or methacrylic acid, or metal crosslinking Polyolefin resin, etc., and adding 5% or more of a butene component, ethylene-propylene-butene copolymer, amorphous ethylene-propylene copolymer, propylene-α-olefin copolymer as necessary It ’s good.

When using acid-modified polypropylene,
(1) A homotype having a bigat softening point of 115 ° C or higher and a melting point of 150 ° C or higher,
(2) A copolymer of ethylene-propylene having a bigat softening point of 105 ° C or higher and a melting point of 130 ° C or higher (random copolymer type)
(3) A simple substance or a blended product obtained by acid-modified polymerization using an unsaturated carboxylic acid having a melting point of 110 ° C. or higher can be used.
The acid-modified polypropylene includes a low crystalline ethylene-butene copolymer having a density of 900 kg / m ³ or less, a low crystalline propylene-butene copolymer, or an amorphous ethylene-propylene copolymer, Add 5% or more of amorphous propylene-ethylene copolymer or ethylene-butene-propylene copolymer (terpolymer) to give flexibility, improve bending resistance, and prevent cracking during molding You may go.

  Next, the fluorine resin layer 26 will be described. The fluorine resin layer 26 can bond the aluminum foil 13 and the heat seal layer 14 by a dry lamination method (see FIG. 2). Further, since the fluorine-based resin layer 26 can suppress water vapor permeability to the same level as that of the thermal lamination method, it is possible to provide a laminate that is excellent in physical properties such as electrolytic solution resistance and corrosion resistance with high productivity. .

  The fluorine-based resin layer 26 is a layer formed of a fluorine-containing copolymer containing a hydroxyl group and a curing agent that reacts with the fluorine-containing copolymer. The fluorine-containing copolymer containing a hydroxyl group is soluble in an organic solvent and has a crosslinking site in the molecule, and examples of the crosslinking site include an alcoholic hydroxyl group (OH group).

As such a fluorine-containing copolymer, for example,
1) a fluoroolefin monomer represented by the formula: CF ₂ = CFX [wherein X is a fluorine atom, a hydrogen atom or a trifluoromethyl group]
2) β-methyl-substituted α-olefin monomer represented by the formula: CH ₂ = CR (CH ₂ ), wherein R is an alkyl group having 1 to 8 carbon atoms,
3) a hydroxyl group-containing monomer represented by the formula: CH ₂ = CHR 1 (wherein R 1 is —OR ₂ or —CH ₂ OR ₂ (where R 2 is an alkyl group having a hydroxyl group)), and
4) Fluorine-containing copolymers derived from other monomers that do not have a crosslinkable functional group and can be copolymerized with the monomers 1), 2), and 3).

  Examples of the fluoroolefin monomer include tetrafluoroethylene, trifluoroethylene, hexafluoropropylene, and the like. Examples of the β-methyl substituted α-olefin monomer include isobutylene, 2-methyl-1-pentene, 2-methyl-1-hexene and the like. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, and 5-hydroxypentyl. Examples include vinyl ether, 6-hydroxyhexyl vinyl ether, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and the like.

  Examples of other monomers that can be copolymerized with the fluoroolefin monomer, the β-methyl-substituted α-olefin monomer, and the hydroxyl group-containing monomer include vinyl acetate, vinyl propionate, (iso ) Carboxylic acid vinyl esters such as vinyl butyrate, vinyl caproate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl xafluoropropionate, vinyl trifluoroacetate, maleic acid or dimethyl fumarate, diethyl, dipropyl, dibutyl, Alkyl vinyl such as diester of maleic acid or fumaric acid such as ditrifluoromethyl, ditrifluoromethyl, dihexafluoropropyl, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, iso-butyl vinyl ether, tert-butyl vinyl ether In addition to ruethers, cycloalkyl vinyl ethers such as cyclopentyl vinyl ether and cyclohexyl vinyl ether, vinyl ethers having aromatic groups such as benzyl vinyl ether, or fluoroalkyl vinyl ethers such as perfluoroethyl vinyl ether and perfluoropropyl vinyl ether, etc. Vinyl acetate, maleic acid, styrene and the like.

  The fluorine-containing copolymer having a hydroxyl group can be obtained by copolymerizing the monomers of the above formulas 1) to 4) by a known method such as emulsion polymerization, solution polymerization, suspension polymerization or the like. The fluorine-containing copolymer having a hydroxyl group has a number average molecular weight measured by GPC of 1,000 to 500,000, preferably 3,000 to 100,000.

  As the curing agent, an organic polyisocyanate compound having high reactivity with a hydroxyl group as a crosslinking site is suitable, for example, 2,4-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, xylylene diisocyanate. , Isophorone diisocyanate, lysine methyl ester diisocyanate, methylcyclohexyl diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, n-pentane-1,4-diisocyanate, and trimers thereof, adducts and burettes thereof, or Examples of these polymers include those having two or more isocyanate groups, and blocked isocyanates.

  Such a fluorine-containing copolymer containing a hydroxyl group is reacted with a curing agent to form a fluorine resin. For example, the fluorine-containing copolymer is dissolved in a solvent, and 0.3 equivalents or more, preferably 0.5 to 2.0 equivalents, based on 1 equivalent of a hydroxyl group (—OH group) in the fluorine-containing copolymer. It is appropriate to add the curing agent. When it is less than 0.3 equivalent, the laminate strength cannot be obtained, and when it exceeds 2.0 equivalent, a large amount of unreacted isocyanate groups may remain and the laminate strength may be lowered.

  Next, the heat seal layer 14 will be described. As the heat seal layer 14, a metal terminal connected to each of the positive electrode and the negative electrode of the lithium battery body is sandwiched in a state of protruding outward, and is thermally bonded to be sealed between the heat seal layer 14 and the metal terminal. The resin type differs depending on whether or not the metal terminal sealing adhesive film is interposed. When an adhesive film for sealing metal terminals is interposed, a film made of a propylene-based resin alone or a mixture may be used. When an adhesive film for sealing metal terminals is not interposed, the graph is modified with unsaturated carboxylic acid. A film made of the acid-modified olefin resin may be used.

  Polypropylene is preferably used as the heat seal layer 14, but a single layer or a single layer or a multilayer of linear low density polyethylene or medium density polyethylene, or a blend resin of linear low density polyethylene or medium density polyethylene, or It can also be used as a multilayer film.

  For each type of polypropylene, that is, random propylene, homopropylene, block propylene, and linear low density polyethylene, medium density polyethylene, low crystalline ethylene-butene copolymer, low crystalline propylene-butene copolymer, A terpolymer composed of a three-component copolymer of ethylene, butene, and propylene, silica, zeolite, an antiblocking agent (AB agent) such as acrylic resin beads, a fatty acid amide slip agent, and the like may be added.

  In addition, it is particularly desirable to include an ethylene / propylene random copolymer in the laminate in the multilayer polypropylene layer. Ethylene / propylene random copolymer is a copolymer of ethylene and propylene, and is an irregular polymerized arrangement of ethylene and propylene repeating units, so it is compared with blended resins that only melted ethylene resin and propylene resin. And very tough.

  Therefore, even when the exterior body is bent after heat sealing, the occurrence of cracks in the heat sealing layer 14 can be prevented. This is because the ethylene / propylene random copolymer is a copolymer, so even when it is melted and solidified at the time of heat sealing, the ethylene and propylene molecules are not separated and solidified. It is to do. Therefore, the ethylene / propylene random copolymer is not easily crystallized even when the heat at the time of heat sealing is retained in the aluminum foil by providing the aluminum foil with a thickness. From the above, the ethylene / propylene random copolymer has a certain toughness even after heat sealing and can be suitably used as a heat sealing layer.

  Further, by using an unstretched polypropylene layer having a melting point of 140 to 180 ° C., as described above, in the lithium ion battery, the temperature inside the outer package 10 rises due to overcharge or the like, and the metal terminal generates heat. Even when the sandwiched portion of the metal terminal 4 of the melt-extruded polypropylene layer 9 which is the innermost layer is melted, it is possible to prevent the metal terminal and the metal foil from contacting and short-circuiting.

  In addition to the base material layer 12, the barrier layer 13, the second adhesive layer 15, and the heat seal layer 14 (polypropylene or polyethylene), between the barrier layer 13 and the heat seal layer 14, polyimide, polyethylene terephthalate, etc. An intermediate layer made of a biaxially stretched film or the like may be provided. An intermediate | middle layer can prevent the short circuit by contact with the tab and barrier layer at the time of the heat | fever seal of the lithium ion battery exterior body at the time of the heat improvement of a lithium ion battery exterior body by improving the strength as a packaging material for lithium ion batteries.

  Next, the melt-extruded polypropylene layer 9 will be described. By additionally processing the polypropylene layer 9 melt-extruded on the surface of the unstretched polypropylene layer that is the heat seal layer of the outer package 10, the heat seal temperature can be lowered while ensuring a predetermined seal strength. This is presumably because the melt-extruded polypropylene layer 9 has a lower melting point and higher fluidity than the unstretched polypropylene layer 16 when heated.

  Usually, when the unstretched polypropylene layer 16 is heat-sealed, it is necessary to apply heat and pressure near the melting point (about 190 ° C.) of the unstretched polypropylene layer to the seal portion. However, by providing the melt-extruded polypropylene layer 9 having a melting point of 120 to 150 ° C. on the surface of the unstretched polypropylene layer, heat sealing can be performed at a temperature lower than the melting point of the unstretched polypropylene layer.

  At this time, if a melt-extruded polypropylene layer 9 having a melt index of 5 g / 10 min or more and 30 g / 10 min or less is used, sufficient seal strength can be secured at the seal temperature.

  Further, when the lithium ion battery main body is sealed in the outer casing 10 and the metal terminal of the battery main body is sandwiched and sealed in a state of protruding outward, the melt-extruded polypropylene layer 9 has high fluidity so that the metal terminal is sandwiched. The opening of the outer package 10 is hermetically sealed so as to cover the entire portion. For this reason, the external water vapor which permeate | transmits from the said metal terminal clamping part can be interrupted | blocked, and the production | generation of hydrofluoric acid by reaction of electrolyte and water vapor | steam can be suppressed.

  Further, when embossing the outer package 10, the melt-extruded polypropylene layer 9 has a lower coefficient of dynamic friction than the unstretched propylene film. It is possible to prevent the occurrence of wrinkles and tears and to perform stable press molding.

  Next, the slip layer 11 will be described. As the slip agent for forming the slip layer 11, a polydimethylsiloxane block copolymer produced by copolymerizing a vinyl copolymer with an azo group-containing polydimethylsiloxane amide as an initiator is used.

  A slip agent using a polydimethylsiloxane block copolymer is deposited and deposited on a molding die or a guide roll when continuously molding using a conventional fatty acid amide slip agent. There is no need to bake at a high temperature when a slip agent deposited on the film adheres to the film, or when a coating such as a fluororesin layer or silicone resin layer slip agent is applied. Therefore, it is a material suitable as a slip agent.

The polydimethylsiloxane block copolymer has the following structure.
[1]. (A ¹ * a ² ) _l
[2]. a ¹ * (a ¹ * a ² ) _m
[3]. a ² * (a ¹ * a ² ) _n
Here, l, m, and n are integers of 1 to 10, a ¹ is a polydimethylsiloxane moiety represented by the following formula (Formula 7),

a ² is a vinyl polymer portion. First, a polymer initiator method is applied to synthesize the polydimethylsiloxane block copolymer. In the above polymer initiator method, for example, if a vinyl short monomer copolymerizable with a polymer having a polydimethylsiloxane moiety represented by the following formula (Chemical Formula 8) is copolymerized, the efficiency is improved. A block copolymer can be produced well.

  Further, if a polymeric initiator such as a peroxide type polymer initiator or an azo type polymer initiator is used, the polymerization can be carried out in two stages. For example, when an azo type polymer initiator is used, the polymerization is a two-stage polymerization represented by the following formulas (Chemical Formula 9) and (Chemical Formula 10):

Here, m, n, n ′, and l are integers of 1 or more, M ₁ is a macromonomer represented by the following formulas (Chemical Formula 11) and (Chemical Formula 12),

Here, M ₂ is a vinyl monomer copolymerizable with M _1. If R is exemplified, it is represented by the following formula (Chemical Formula 13).

and so on.

Next, examples of the copolymerizable vinyl monomer used in the polymer initiator method include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl ( (Meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, Aliphatic or cyclic (meth) acrylate such as stearyl (meth) acrylate, theuryl (meth) acrylate, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, iso-butyl vinyl ether, etc. Nyl ethers, styrenes such as styrene and α-methylstyrene, nitrile monomers such as acrylonitrile and methacrylonitrile, aliphatic vinyls such as vinyl acetate and vinyl propionate, vinyl chloride, vinylidene chloride, vinyl fluoride, and fins , Dienes such as chloroprene, butadiene, acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, α, β-unsaturated carboxylic acid such as crotonic acid, atropaic acid, citraconic acid, acrylamide, methacrylamide, Amides such as N, N-methylolacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, methylacrylamide glycolate methyl ether, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminomethyl (Meta) Acry , Amino group-containing monomers such as N, N-dimethylaminopropyl (meth) acrylate, epoxy group-containing monomers such as glycidyl (meth) acrylate and glycidyl allyl ether, 2-hydroxyethyl (meth) acrylate, Reaction products of 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, allyl alcohol, Cardura E with acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, etc., other vinylpyrrolidone, vinylpyridine, vinylcarbazole In addition, vinyl monomers having a hydrolyzable silyl group include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacrylo Shi propyl methyl diethoxy silane, .gamma.-methacryloxypropyl methoxy silane, vinyl trimethoxy silane, can be used silane coupling agents such as vinyltriethoxysilane. The above monomers may be used alone or in combination of two or more. In this stage, (meth) acrylate is used in the meaning of acrylate or methacrylate.

  As a method for producing the polydimethylsiloxane block copolymer, it is produced by adding a vinyl monomer copolymerizable with the above-described polymer initiator into which polydimethylsiloxane is introduced and polymerizing it. The polymerization reaction is usually performed in a solution. In the above polymerization reaction, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, propyl acetate, butyl acetate and isobutyl acetate, methanol, It can be used alone or as a mixed solvent such as alcohol solvents such as ethanol, isopropanol, butanol and isobutanol.

  In the above polymerization reaction, a known polymerization initiator such as benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, dicumyl peroxide or the like may be used in combination as necessary. . In the polydimethylsiloxane block copolymer thus obtained, the siloxane content ratio is 1 to 60% by weight, preferably 5 to 40% by weight, and the content ratio of other copolymerizable vinyl monomers is 99 to 40%. It is desirable that the vinyl monomer has an OH group or an epoxy group contained therein, preferably 95% to 60% by weight. The polydimethylsiloxane block copolymer thus obtained is highly compatible with other synthetic resins and is extremely effective as a compatibilizing agent. For example, silicone resin, polyvinyl acetoacetal, polyvinyl butyral A synthetic resin such as the above may be used as a mixture.

When a polydimethylsiloxane block copolymer is used as a slip agent, a resin solution containing the polydimethylsiloxane block copolymer obtained by the above polymerization reaction in a solution is applied by a known coating method such as a gravure printing method. The slip agent layer 11 can be obtained by applying to the surface of the base material layer and drying. The coating amount of the polydimethylsiloxane block copolymer is 0.05 g / m ² or more after drying, preferably 0.08 to 0.5 g / m ² , more preferably 0.1 to 0.2 g / m. m ² . Is less than the coating amount is 0.05 g / m ^2, there is no stable sliding properties can be obtained (slipperiness varies) risk, even at 0.5 g / m ² greater, although the sufficient effect of the sliding property is obtained This is not preferable in terms of cost effectiveness.

  The present invention is not limited to the above-described embodiments, and various modifications are possible. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the present invention. Included in the technical scope. Hereinafter, the battery packaging material of the present invention will be specifically described in Examples.

  A chemical conversion treatment is applied to both sides of an aluminum foil (thickness 40 μm), and one side of the chemical conversion treatment surface is bonded with a stretched nylon film (thickness 25 μm) by a dry laminating method via a two-component curable polyurethane adhesive. An acid-modified polypropylene (hereinafter abbreviated as acid-modified PP) (thickness: 15 μm) was melt-extruded and a sealant film made of an unstretched polypropylene film (thickness: 30 μm) was laminated on the chemical conversion treated surface by a thermal lamination method.

At this time, in each chemical conversion treatment, an aqueous solution composed of a phenol resin, a chromium fluoride compound, and phosphoric acid was used as a treatment solution, and the coating was applied by a roll coating method and baked under a condition where the film temperature was 180 ° C. or higher. The amount of chromium applied was 10 mg / m ² (dry weight).

  Next, a polypropylene layer having a melting point of 139 ° C. and a melt index of 20 g / 10 min was melt-extruded to a thickness of 20 μm on the surface of the unstretched polypropylene layer of the laminate to obtain a laminate of the present invention.

  Moreover, the laminated body before carrying out melt extrusion of the polypropylene on the surface of the said unstretched polypropylene layer was made into the comparative example.

  The obtained laminates of the present invention and the comparative example were evaluated by the following evaluation methods, and the relationship between the seal temperature, the seal strength, and the sealant residual rate was summarized in graphs 1 and 2.

[Graph 1]

[Graph 2]

  As an evaluation method for showing the relationship between the seal temperature and the seal strength, the laminate thus produced is cut into strips of 60 mm (MD direction) × 120 mm (TD direction), folded in half in the TD direction, and facing 2 The side was heat-sealed with a width of 7 mm to produce a bag having an opening on one side, and the opening was heat-sealed with a width of 7 mm, a surface pressure of 1.0 MPa, and a sealing time of 3.0 seconds. At this time, samples sealed under different conditions such as 150 ° C., 170 ° C., 190 ° C., and 210 ° C. were produced for each of the laminates.

  Next, the heat seal part at the opening of these samples was cut into a strip of 15 mm width, and this was pulled with a tensile tester (manufactured by Shimadzu Corporation, AGS-50D (trade name)) at a speed of 300 mm / min, and heat sealed. The strength was measured. The unit is N / 15 mm width.

  As an evaluation method showing the relationship between the sealing temperature and the amount of crushing, a bag having an opening is prepared in the same manner as the above method, the opening is 7 mm wide, the surface pressure is 1.0 MPa, and the sealing time is 3.0 seconds. did. At this time, samples sealed under different conditions such as 150 ° C., 170 ° C., 190 ° C., and 210 ° C. were produced for each of the laminates. Next, the total thickness of the laminate in the opening before and after heat sealing of these samples was measured, and the value obtained by dividing the total thickness before heat sealing from the total thickness after heat sealing was the sealant residual rate (%) It was.

  As can be seen from graph 1, it was found that the melt strength was improved by providing the melt-extruded polypropylene layer on the surface of the unstretched polypropylene layer laminated by the thermal lamination method. Moreover, it was found from this that even when the sealing temperature was lowered, sufficient sealing strength could be ensured by melt extrusion of the polypropylene layer.

  Further, as is apparent from graph 2, it was found that by providing a melt-extruded polypropylene layer on the surface of the unstretched polypropylene layer, the sealant residual rate of the laminate during heat sealing was lowered. It can be seen that this is mainly due to the collapse of the melt-extruded polypropylene layer by comparison with the sealant residual ratio of the comparative example. Therefore, by the fluidity of the melt-extruded polypropylene layer, it can be hermetically sealed so as to cover the entire metal terminal sandwiched portion, shuts off external water vapor that permeates from the metal terminal sandwiched portion, and reacts with the reaction between the electrolyte and water vapor. It is thought to suppress the production of hydrofluoric acid.

  Next, in Example 2, in the heat seal layer composed of a multilayer film, the seal strength that changes with time depending on the melting point and the melt index of the formed film was evaluated.

  First, both surfaces of aluminum (thickness 30 μm) are subjected to chemical conversion treatment, and one of the chemical conversion treatment surfaces is pasted with a biaxially stretched nylon film (thickness 25 μm) by a dry laminating method via a two-component curable polyurethane adhesive. Combined. Next, acid-modified PP (thickness 15 μm) is melt-extruded on the other chemical conversion treatment surface, and a three-layer coextruded film (thickness) comprising an ethylene / propylene random copolymer film and an ethylene / propylene block copolymer film sandwiched therebetween. 30 μm) was laminated, and a polypropylene layer was melt-extruded to a thickness of 20 μm on the surface of the three-layer coextruded film layer to obtain a battery packaging material according to the present invention 2.

  The melting point Mp and the melt index Mi of the three-layer coextruded film constituting the heat seal layer and the melt-extruded polypropylene layer are Mp = 143 ° C., Mi = 1.0 g / 10 min for ethylene / propylene random copolymer film, ethylene The propylene block copolymer film has Mp = 165 ° C., Mi = 15 g / 10 min, and the melt-extruded polypropylene has Mp = 139 ° C., Mi = 20 g / 10 min. Therefore, the heat-sealed layer constituting the battery packaging material according to the second aspect of the present invention is provided with a melt-extruded polypropylene having the lowest melting point and the highest melt index as the innermost layer.

  Further, a battery packaging material in which a polypropylene layer was not melt-extruded on the three-layer coextruded film was prepared as Comparative Example 2.

Moreover, the chemical conversion treatment layer was coated with a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid by a roll coating method, and baked under conditions where the film temperature was 90 ° C. or higher. The amount of chromium applied was 10 mg / m ² (dry weight).

  Next, the battery packaging material according to the present invention 2 and comparative example 2 is cut into strips of 60 mm (MD direction) × 120 mm (TD direction), folded in half in the TD direction, and the two opposing sides are 7 mm. A bag having an opening on one side is prepared by heat sealing with a width, and 3 g of electrolytic solution [mixed solution of lithium hexafluorophosphate [ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (volume Ratio)] and a 1 mol / L lithium hexafluorophosphate solution] is injected, and the opening is 7 mm wide, the seal temperature is 190 ° C., the surface pressure is 1.0 MPa, and the seal time is 3.0 seconds. After heat-sealing and sealing, the heat-sealed portion in the opening of the sample stored for 0, 72, 168, 336, and 504 hours in a 60-degree thermostatic oven is cut into a 15 mm wide strip. A tensile tester (manufactured by Shimadzu Corporation, AGS-50D (trade name)) pulled at at 300 mm / min, the seal strength at each storage time was measured the results are summarized in Graph 3. The unit of seal strength is N / 15 mm width.

[Graph 3]

  Next, the seal part of the sample concerning this invention 2 and the comparative example 2 heat-sealed on the said conditions is cut | disconnected, the cross-sectional view is observed with a microscope, The cross-sectional photograph is shown in FIG. 7A is a cross-sectional photograph of the exterior body according to Comparative Example 2, and FIG. 7B is a cross-sectional photograph of the exterior body according to the first aspect of the present invention.

  As described above, from the results shown in [Graph 3], it was found that the exterior body according to the second aspect of the present invention maintains a high seal strength over time as compared with the exterior body according to Comparative Example 2. Further, from the cross-sectional photograph of FIG. 7, the vicinity of the inner edge of the seal part of the outer package according to the present invention 2 forms a parabolic surface and is stably sealed, whereas the inner edge of the seal part of the outer package according to the comparative example 2 Resin accumulation was confirmed in the vicinity. Therefore, it can be estimated that this resin pool is one of the causes that the seal strength of the exterior body according to Comparative Example 2 is lower than the seal strength of the exterior body according to the present invention 2 over time.

  TECHNICAL FIELD The present invention relates to a battery packaging material suitable for use as a power source for energy storage or electric vehicles and used in a lithium ion battery having high durability and safety.

These are schematic sectional drawings which show the layer structure of the packaging material for batteries of this invention. These are schematic sectional drawings which show the layer structure of the packaging material for batteries of this invention. These are the expanded sectional views which show the structure of the metal terminal periphery of the lithium ion battery using the packaging material for batteries of this invention. These are sectional drawings of the packaging material for batteries concerning this invention which shows the flow of the heat seal layer at the time of heat sealing. These are the schematic perspective views which show the process of embossing the packaging material for batteries of this invention. These are the schematic perspective view and sectional drawing at the time of accommodating the lithium ion battery using the packaging material for batteries of this invention in the plastic case. These are the cross-sectional photographs of the exterior body in Example 2. FIG. FIG. 2 is a schematic perspective view showing a conventional pouch-type lithium ion battery in an exploded manner. FIG. 2 is a schematic perspective view showing a conventional embossed type lithium ion battery in an exploded manner. These are the schematic diagrams which show the conventional embossing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lithium ion battery 2 Lithium ion battery main body 3 Cell (electric storage part)
4 Metal terminal (tab)
7 Clamping part 8 Acid-modified polyolefin layer (adhesive layer)
9 Melt Extruded Polypropylene Layer 10 Exterior Body 10a Near Inner Edge of Seal Part 10b Outer Body Peripheral Part 10c Bent Part 12 Base Material Layer 13 Metal Foil Layer 13a Chemical Treatment Layer (Metal Foil Layer Surface)
DESCRIPTION OF SYMBOLS 14 Heat seal layer 15 Adhesive layer 16 Unstretched polypropylene layer 19 Plastic case 20 Press molding part 21 Male part 22 Female type | mold 22a Side wall part 23 Cavity 24 2nd polypropylene layer 25 1st polypropylene layer 25a Resin pool 26 Fluorine-type resin layer (Adhesive layer)

Claims (5)

The base material layer that is the outermost layer, the barrier layer made of aluminum foil, the chemical conversion treatment layer, the adhesive layer, and the heat seal layer that is the innermost layer are laminated at least sequentially,
The heat seal layer has at least a first polypropylene layer and a second polypropylene layer,
The second polypropylene layer is disposed on the innermost layer side of the first polypropylene layer, has a lower melting point and a higher melt index than the first polypropylene layer, and the first polypropylene layer is made of an unstretched polypropylene film. In the method for producing a packaging material, the unstretched polypropylene film comprises a three-layer coextruded film in which an ethylene / propylene block copolymer is sandwiched between two layers of ethylene / propylene random copolymer, and the ethylene / propylene block copolymer is the ethylene / propylene A method for producing a battery packaging material , wherein the melting point is higher than that of a random copolymer, and the second polypropylene layer is laminated by extruding polypropylene onto the unstretched polypropylene film. A battery packaging material produced by the production method according to claim 1,
The melt index of the second polypropylene layer is 5 g / 10 min or more and 30 g / 10 min or less, the melting point of the second polypropylene layer is 120 ° C. or more and 150 ° C. or less, and the melting point of the first polypropylene layer is 140 ° C. or more. A battery packaging material characterized by being 180 ° C. or lower. The battery packaging material according to claim 2, wherein the base material layer is made of stretched polyester or polybutylene terephthalate . The battery packaging material according to claim 2 or 3 , wherein a coating layer of a slip agent is provided on the surface of the base material layer . The battery packaging material according to any one of claims 2 to 4, wherein the adhesive layer is made of an acid-modified polyolefin .