JP2011054563A - Packaging material for electrochemical cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging material for an electrochemical cell having an identification mark that can be recognized from the outside and is difficult to be forged, and preventing the generation of a float or a wrinkle by layer separation caused by heat in a sealing process after forming. <P>SOLUTION: The packaging material for the electrochemical cell is composed of a multilayer film having structure formed by laminating at least a substrate layer, an adhesive layer, a metal foil layer, and a heat-bondable resin layer in this order, and pigment is added to the adhesive layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a packaging material for an electrochemical cell that has an identification mark that is recognizable from the outside and difficult to counterfeit, and that does not delaminate due to heat applied in the sealing process after molding, and does not cause floating or wrinkles. .

  In recent years, as shown in Patent Document 1, for example, a lithium ion battery, a lithium polymer battery, a fuel cell, or a liquid capacitor including a dielectric such as a liquid, a solid ceramic, an organic substance, a solid capacitor, a double layer capacitor, etc. In the electrochemical cell, a packaging material for an electrochemical cell composed of a multilayer film is used as an exterior body.

  FIG. 2 is a cross-sectional view showing a layer structure of a conventional electrochemical cell packaging material. As shown in FIG. 2, the conventional electrochemical cell packaging material 110 includes at least a base material layer 111, a metal foil layer 112, The base material layer 111 and the metal foil layer 112 are bonded via an adhesive layer 113, and the heat adhesive resin layer 115 and the metal foil layer 112 are formed of an acid-modified polyolefin layer 114. Is glued through.

  3A is an exploded perspective view of a lithium ion battery using a conventional embossed type exterior body, and FIG. 3B is a perspective view of a lithium ion battery using a conventional embossed type exterior body. It is. As shown in FIGS. 3A and 3B, in the cold press molding process, the lithium ion battery 121 is formed by cold pressing the electrochemical cell packaging material 110 shown in FIG. The lithium ion battery main body 122 is accommodated inside the tray 120a having a recess, the opening of the tray 120a is closed with the sheet 120b, and in the sealing step, the heat adhesive resin layers 115 of the tray 120a and the sheet 120b are overlapped with each other, It is produced by heat sealing the periphery.

  The lithium ion battery 121 manufactured in this way is attached with a label on which the product information is written on the surface of the exterior body 120 in the final step of battery manufacture, or directly on the surface of the exterior body 120 instead of the label. Product information etc. are printed by inkjet. Similarly, an identification mark is also attached to the electrochemical cell packaging material 110 itself used for the exterior body 120.

  However, when a counterfeit lithium ion battery 121 or an electrochemical cell packaging material 110 different from a regular manufacturer is attached with the same identification mark as the regular manufacturer by the above method, a genuine product and a counterfeit product are discriminated. It becomes difficult.

JP 2007-273398 A

  Conventionally, in order to solve this problem, a method of discriminating between a regular product and a counterfeit product using a hologram label as an identification mark has been proposed. However, the hologram label increases the cost of the product, and the hologram label may be forged.

  FIG. 4 is a cross-sectional view showing a layer structure of a conventional packaging material for electrochemical cells. As shown in FIG. 4, a printing layer 119 formed of ink is newly formed on one surface of the base material layer 111. A method of providing and configuring the packaging material 210 for electrochemical cells is also conceivable. However, the adhesive strength between the base material layer 111 and the metal foil layer 112 is lowered by providing the printed layer 119 in the packaging material 210 for electrochemical cells. For this reason, as shown in FIG. 3, after forming a recess by press molding the electrochemical cell packaging material 210 in the cold press molding process, the sealing is performed when the periphery is heat sealed in the sealing process. There is a problem that the base material layer 111 processed into a concave shape by heat in the process shrinks to return to its original shape, and the base material layer 111 and the metal foil layer 112 are peeled off to cause floating and wrinkles.

  Therefore, in view of the above problems, the present invention has an identification mark that is recognizable from the outside and difficult to counterfeit, and does not generate delamination or wrinkles due to delamination due to heat applied in the sealing process after molding. It aims at providing the packaging material for cells.

  To achieve the above object, the present invention provides a packaging material for an electrochemical cell, a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, and a positive electrode and a negative electrode An electrochemical cell main body including an electrolyte filled in between, and sealing the electrochemical cell main body by heat-sealing a peripheral portion, at least a base material layer, an adhesive layer, a metal foil layer, and thermal bonding The resin layer is composed of a multilayer film having a structure in which the resin layers are laminated in this order, and any one of the base material layer, the adhesive layer, and the metal foil layer includes an identification mark.

  According to this configuration, since the identification mark is included in any one of the base material layer, the adhesive layer, and the metal foil layer constituting the electrochemical cell packaging material, the electrochemical cell packaging material itself has an identification function. Even when a label serving as a counterfeit identification mark is attached or printed on the packaging material for electrochemical cells, authenticity determination can be easily performed. In addition, any one of the base material layer, the adhesive layer, and the metal foil layer constituting the electrochemical cell packaging material includes an identification mark, and there is no need to provide a new layer for the identification mark. For this reason, the adhesive strength between the base material layer and the metal foil layer does not decrease, and a predetermined adhesive strength can be maintained. As a result, when forming the packaging material for electrochemical cells by press molding or the like, the heat applied in the sealing process after molding peels off between the base material layer and the metal foil layer, and floats and wrinkles are generated. Can be prevented.

  According to a second configuration of the present invention, in the electrochemical cell packaging material according to the first configuration, the identification mark is configured by a pigment contained in the adhesive layer.

  According to this configuration, the adhesive layer is colored by the pigment contained in the adhesive layer, and the packaging material for electrochemical cells can be identified by this color. For this reason, even if a label that becomes a counterfeit identification mark is attached to the packaging material for electrochemical cells or printed, the authenticity of the product is determined by the difference in color that can be recognized from the appearance of the packaging material for electrochemical cells. Can be easily determined. In addition, since the adhesive layer itself that bonds the base material layer and the metal foil layer is colored, the adhesive strength between the base material layer and the metal foil layer does not decrease, and a predetermined adhesive strength can be maintained. . As a result, even when the packaging material for electrochemical cells is molded by press molding or the like, the base layer and the metal foil layer are peeled off by heat applied in the sealing process after molding, and floating and wrinkles are generated. Can be prevented.

  A third configuration of the present invention is characterized in that, in the packaging material for an electrochemical cell of the first configuration, the identification mark is composed of a pigment contained in a stretched nylon film constituting the base material layer. .

  According to this structure, the base material layer is colored by the pigment contained in the stretched nylon film constituting the base material layer, and the packaging material for electrochemical cells can be identified by this color. For this reason, even if a label that becomes a counterfeit identification mark is attached to the packaging material for electrochemical cells or printed, the authenticity of the product is determined by the color difference that can be recognized from the appearance of the packaging material for electrochemical cells. Can be easily determined. Further, since the base material layer itself is colored, the adhesive strength between the base material layer and the metal foil layer is not lowered, and a predetermined adhesive strength can be maintained. As a result, even when the packaging material for electrochemical cells is molded by press molding or the like, the base layer and the metal foil layer are peeled off by heat applied in the sealing process after molding, and floating and wrinkles are generated. Can be prevented.

  A fourth configuration of the present invention is characterized in that, in the packaging material for an electrochemical cell of the first configuration, the identification mark is configured by unevenness applied to the surface of the metal foil constituting the metal foil layer. To do.

  According to this structure, the packaging material for electrochemical cells can be identified by the unevenness | corrugation given to the metal foil surface. For this reason, even if a label that becomes a counterfeit identification mark is affixed or printed on the packaging material for electrochemical cells, the authenticity of the product can be determined by the unevenness that can be recognized from the appearance of the packaging material for electrochemical cells. Can be easily performed. In addition, since the metal foil layer itself is provided with unevenness, and the uneven metal foil layer is laminated with the base material layer via the adhesive layer, the adhesive strength between the base material layer and the metal foil layer The predetermined adhesive strength can be maintained without lowering. As a result, even when the packaging material for electrochemical cells is molded by press molding or the like, the base layer and the metal foil layer are peeled off by heat applied in the sealing process after molding, and floating and wrinkles are generated. Can be prevented.

  According to a fifth aspect of the present invention, in the electrochemical cell packaging material according to the second aspect, the pigment is a pearl pigment.

  According to this structure, the packaging material for electrochemical cells is colored by the pearl pigment, and the packaging material for electrochemical cells can be identified by this color.

  According to a sixth aspect of the present invention, in the electrochemical cell packaging material according to the first aspect, the pigment is a fluorescent pigment.

  According to this configuration, the fluorescent pigment is colored and the packaging material for electrochemical cells is colored, and the packaging material for electrochemical cells can be identified by this color.

  According to a seventh configuration of the present invention, in the electrochemical cell packaging material of the second configuration, a mat varnish layer is formed on the upper surface of the base material layer.

  According to this structure, the mat | matte varnish layer can increase the slipperiness of the packaging material surface for electrochemical cells, and can reduce molding defects in the embossing molding process. Further, the slipperiness can be adjusted by adjusting the addition amount of the lubricant added to the mat varnish, and the matting effect can be adjusted by adjusting the particle size and the addition amount of the mat material.

  The eighth configuration of the present invention is characterized in that, in the electrochemical cell packaging material of the second configuration, the base material layer is composed of a stretched nylon film whose surface is matted.

  According to this configuration, the matted stretched nylon film increases the slipperiness of the surface of the packaging material for electrochemical cells, and can reduce molding defects in the cold press molding process. Moreover, the matte effect can be exhibited on the surface of the base material layer by processing the upper surface of the base material layer to a predetermined surface roughness and performing a mat treatment. Thereby, a design can be formed in the whole base material layer together with the identification mark formed in the inner layer side from the base material layer. Further, the matte film that has been subjected to a matte treatment by processing the surface is less likely to have a delustering effect because the surface of the base material layer is worn or pressed during press molding. Moreover, even when the solvent of an electrochemical cell adheres, a matting effect is hard to fall.

  According to a ninth configuration of the present invention, in the electrochemical cell packaging material of the second configuration, an acid-modified polyolefin layer is interposed between the metal foil layer and the heat-adhesive resin layer.

  According to this structure, a metal foil layer and a heat bondable resin layer can be adhere | attached stably.

These are sectional drawings which show the layer structure of the packaging material for electrochemical cells of this invention. These are sectional drawings which show the layer structure of the conventional packaging material for electrochemical cells. These are the exploded perspective views of the lithium ion battery using the conventional embossed type exterior body. These are perspective views of the lithium ion battery using the conventional embossed type exterior body. These are sectional drawings which show the layer structure of the conventional packaging material for electrochemical cells.

  The present invention has an identification mark that can be recognized from the outside and difficult to counterfeit, and a packaging material for an electrochemical cell that does not cause delamination due to heat applied to the sealing process after molding and does not cause floating or wrinkles This will be described in more detail using. Note that the description of the portions common to FIGS. 2 to 4 of the conventional example is omitted.

  FIG. 1 is a cross-sectional view showing the layer structure of an electrochemical cell packaging material of the present invention. As shown in FIG. 1, the electrochemical cell packaging material 10 of the present invention has a base material layer 11 and an innermost layer as an outermost layer. The heat-adhesive resin layer 15 and the metal foil layer 12 are disposed therebetween, and the heat-adhesive resin layer 15 and the metal foil layer 12 are bonded via the acid-modified polyolefin layer 14. Moreover, the base material layer 11 and the metal foil layer 12 are bonded via an adhesive layer 13. At this time, a chemical conversion treatment layer 12 a is provided on the surface of the metal foil layer 12. In addition, the packaging material 10 for electrochemical cells of this invention shall also include the case where a different layer is interposed between each layer while including each said layer in the technical scope of this invention.

  Here, the adhesive layer 13 is composed of an adhesive containing a colorant such as titanium oxide, and the adhesive layer 13 is colored white. Thereby, the packaging material 10 for electrochemical cells is identified with white as seen from the base material layer 11 side having permeability. For this reason, even if the label used as the forgery identification mark is stuck on the surface of the base material layer 11 of the packaging material 10 for electrochemical cells, or printing is given, it recognizes from the external appearance of the packaging material 10 for electrochemical cells. The authenticity of the product can be easily determined by the difference in colors that can be made. Further, since the adhesive layer 13 itself that bonds the base material layer 11 and the metal foil layer 12 contains a colorant such as titanium oxide, the adhesive strength between the base material layer 11 and the metal foil layer 12 is almost reduced. do not do. Thereby, even when the packaging material 10 for electrochemical cells is formed by cold press molding or the like, the base layer and the metal foil layer are peeled off by the heat applied in the sealing process after molding, and floating and wrinkles are generated. Occurrence can be prevented.

  The adhesive layer 13 is preferably composed of an adhesive to which a colorant such as titanium oxide is added in a solid content of 5 wt% to 30 wt%, preferably 10 wt% to 25 wt%. . In addition, when the addition amount of a coloring agent is less than 5 weight%, the color to be colored becomes light and difficult to identify. Moreover, when the addition amount of a coloring agent exceeds 30 weight%, the adhesive strength of the base material layer 11 and the metal foil layer 12 will become weak, and the base material layer 11 will return to the original shape with the heat | fever concerning the sealing process after shaping | molding. Thus, the base material layer 11 and the metal foil layer 12 are peeled off to cause floating and wrinkles, which is not preferable. Moreover, the shade of the color to be colored can be expressed by adjusting the addition amount of the colorant. Thereby, the packaging material 10 for electrochemical cells can also be identified by the color shading.

  As the colored pigment, a chromatic colored pigment or an inorganic colored pigment can be used.Examples of the chromatic colored pigment include an azo pigment, a phthalocyanine pigment, and a condensed polycyclic pigment. As azo pigments, soluble pigments such as Looting Red and Carmine 6C, insoluble azo pigments such as monoazo yellow, disazo yellow, pyrazolone orange, red and permanent red, phthalocyanine pigments as copper phthalocyanine pigments, and metal-free phthalocyanine pigments as blue Examples of green pigments and condensed polycyclic pigments include dioxazine violet and quinacridone violet. Examples of inorganic coloring pigments include titanium oxide and carbon black.

Further, the adhesive layer 13 can be colored with a pearl pigment or a fluorescent pigment in addition to a colored pigment such as titanium oxide. As the pearl pigment, pearl powder or powder of the inner part of the shell was used classically, but now the outer side of the fine flakes (flakes) is coated with a metal oxide or a mixture of metal oxides Is used. Examples of fine flakes include mica, talc, kaolin, bismuth oxychloride, glass flakes, SiO ₂ flakes, and synthetic ceramic flakes. Examples of metal oxides that coat the outside of these fine flakes Are TiO ₂ , Fe ₂ O ₃ , SnO ₂ , Cr ₂ O ₃ , and ZnO. Among these combinations, mica, glass flakes, or SiO ₂ flakes coated with TiO ₂ and / or Fe ₂ O ₃ are preferable. In addition, the fluorescent pigment is a phosphor, that is, a substance that emits luminescence in a broad sense, and includes both inorganic fluorescent pigments and organic fluorescent pigments. Inorganic fluorescent pigments include oxidation of Ca, Ba, Mg, Zn, Cd, and the like. Mainly composed of crystals such as oxides, sulfides, silicates, phosphates and tungstates, and metal elements such as Mn, Zn, Ag, Cu, Sb and Pb or rare earth elements such as lanthanoids as activators A pigment obtained by adding and baking can be used. As preferred phosphors, ZnO: Zn, Br ₅ (PO ₄ ) ₃ Cl: Eu, Zn ₂ GeO ₄ : Mn, Y ₂ O ₃ : Eu, Y (P, V) O ₄ : Eu, Y ₂ O ₂ Si: Eu, Zn ₂ GeO ₄ : Mn and the like can be exemplified, and examples of organic fluorescent pigments include diaminostilbene disulfonic acid derivatives, imidazole derivatives, coumarin derivatives, triazole, carbazole, pyridine, naphthalic acid, imidazolone derivatives, fluorescein, eosin, etc. A compound having a benzene ring such as a dye or anthracene can be used.

  The base material layer 11 is composed of a stretched nylon film. In addition, in order to improve the slipperiness to the mold surface of the base material layer surface of the packaging material 10 for battery chemical cells, the base material layer 11 is made of a matted stretched nylon film, or the base material layer is made of stretched nylon. A mat varnish layer can be formed on the upper surface of the base material layer. Thereby, a shaping | molding defect can be reduced in the shaping | molding process which shape | molds the packaging material 10 for electrochemical cells by cold press molding etc. FIG.

  Specifically, the matt varnish layer is made of, for example, cellulose, polyamide, vinyl chloride, modified polyolefin, rubber, acrylic, urethane, or other olefin or alkyd synthetic resin, silica or kaolin. A mat varnish to which an appropriate amount of an inorganic material-based matting agent such as the above is added can be used. Alternatively, a mat varnish obtained by adding an appropriate amount of a matting agent and a wax of an inorganic material such as silica or kaolin to the olefin-based or alkyd-based synthetic resin can be used. The method for forming the mat varnish layer is not particularly limited. For example, an offset printing method, a gravure printing method, a flexographic printing method, a silk screen printing method, a roll coating method, a reverse coating method, or the like is appropriately used. be able to.

  The same effect can be obtained by using a stretched nylon film containing a color pigment in the base material layer 11 instead of using an adhesive containing a color pigment such as titanium oxide in the adhesive layer 13. it can. That is, the base material layer 11 is colored by the color pigment contained in the stretched nylon film constituting the base material layer 11, and the packaging material 10 for electrochemical cells can be identified by this color. For this reason, even when a label serving as a counterfeit identification mark is attached to the packaging material 10 for electrochemical cells, or when printing is applied, the difference in color that can be recognized from the appearance of the packaging material 10 for electrochemical cells is True / false discrimination can be easily performed. Moreover, since the base material layer 11 itself is colored, the adhesive strength between the base material layer 11 and the metal foil layer 12 is not lowered, and a predetermined adhesive strength can be maintained. Thereby, even when the packaging material 10 for electrochemical cells is formed by press molding or the like, the base layer and the metal foil layer are peeled off by heat applied in the sealing process after molding, and floating and wrinkles are generated. This can be prevented. At this time, by using a stretched nylon film whose surface is matted, the slipperiness of the surface of the packaging material 10 for electrochemical cells is increased, and molding defects in the cold press molding process can be reduced. As described above, the base material layer 11 is made of a stretched nylon film not subjected to mat treatment instead of the stretch nylon film having a surface subjected to mat treatment, and the base material layer 11 A similar effect can be obtained even if a mat varnish layer is formed on the upper surface of 11.

  Instead of using an adhesive containing a color pigment in the adhesive layer 13 or using a stretched nylon film containing a color pigment in the base material layer 11, fine irregularities on the surface as the metal foil layer 12. The same effect can be obtained even when a mat-processed metal foil having a metallization or a metal foil partially provided with unevenness is used. That is, the packaging material 10 for electrochemical cells can be identified by the unevenness applied to the metal foil constituting the metal foil layer 12. For this reason, even if a label serving as a counterfeit identification mark is attached or printed on the packaging material 10 for electrochemical cells, the authenticity of the product can be recognized by the unevenness that can be recognized from the appearance of the packaging material 10 for electrochemical cells. Can be easily determined. Moreover, the adhesive strength between the base material layer 11 and the metal foil layer 12 is not lowered by using a metal foil having fine irregularities on the metal foil constituting the metal foil layer 12. Therefore, even when the packaging material 10 for electrochemical cells is molded by cold press molding or the like, the base layer and the metal foil layer are separated by the heat applied in the sealing process after molding, and floating and wrinkles are generated. Can be prevented.

  Next, each layer which comprises the packaging material 10 for electrochemical cells which concerns on this invention shown in FIG. 1 is demonstrated concretely. The base material layer 11 may use a stretched polyester film in addition to the stretched nylon film. At this time, examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer 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.

  Next, the adhesive layer 13 will be described. The adhesive layer 13 is a layer that adheres the base material layer 11 and the metal foil layer 13 by a dry laminating method. For example, a polyvinyl acetate adhesive, a homopolymer such as ethyl acrylate, butyl, 2-ethylhexyl ester, etc. Or polyacrylic acid ester adhesives, cyanoacrylate adhesives, ethylene and vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc. made of a copolymer of these with methyl methacrylate, acrylonitrile, styrene, etc. Ethylene copolymer adhesive made of copolymer with other monomers, cellulose adhesive, polyester adhesive, polyamide adhesive, polyimide adhesive, amino resin adhesive made of urea resin or melamine resin, etc. , Phenolic resin adhesive, epoxy adhesive, polyurethane adhesive, reactive type Meth) acrylic adhesives, chloroprene rubber, nitrile rubber, styrene - butadiene made of rubber or the like rubber adhesive, a silicone-based adhesive, an alkali metal silicate, inorganic adhesive or the like made of a low-melting glass.

  Next, the metal foil layer 12 will be described. The metal foil layer 12 is a layer for preventing water vapor from entering the inside of the lithium ion battery from the outside, and the pinhole and processing suitability (pouching, cold press formability) of the metal foil layer alone are stabilized. For example, a film having a thickness of 15 μm or more, such as aluminum or nickel, or a film in which an inorganic compound such as silicon oxide or alumina is vapor-deposited is used. The metal foil to be configured is preferably aluminum having a thickness of 20 to 100 μm.

  Moreover, in order to improve the occurrence of pinholes and to make the outer body type of the lithium ion battery an embossed type, there is no occurrence of cracks or the like in cold press molding. It is desirable that the material has an iron content of 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight.

  As a result, compared with aluminum that does not contain iron, aluminum has good spreadability, the occurrence of pinholes caused by bending as an exterior body is reduced, and the side wall is easily formed when cold-pressing the packaging material. be able to. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement of cold press formability are not recognized, and the iron content of aluminum is 9.0% by weight. In the case of exceeding, the flexibility as aluminum is inhibited, and the bag-making property as a packaging material 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.

  That is, the annealing conditions may be appropriately selected in accordance with processability (pouching, cold press molding). For example, in order to prevent wrinkles and pinholes during cold press molding, soft aluminum annealed according to the degree of molding can be used.

  Moreover, by performing a chemical conversion treatment on the front and back surfaces of the aluminum that is the metal foil layer 12 to form the chemical conversion treatment layer 12a, the adhesive strength with the adhesive can be improved.

  Next, the chemical conversion treatment layer 12a will be described. As shown in FIG. 1, the chemical conversion treatment layer 12 a is formed on at least the surface of the metal foil layer 12 on the thermal adhesive resin layer 15 side. The chemical conversion treatment layer 12 a stably adheres the acid-modified polyolefin layer 14 and the metal foil layer 12, and can prevent delamination of the metal foil layer 12 and the heat-adhesive resin layer 15. Further, the chemical conversion treatment layer 12 a also has a function of preventing the corrosion of the metal foil layer 12.

  Specifically, delamination between the metal foil layer 12 and the heat-adhesive resin layer 15 during embossing by forming an acid-resistant film such as phosphate, chromate, fluoride, triazine thiol compound, etc. And hydrogen fluoride produced by the reaction between the electrolyte and water in 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. Surface adhesion can be improved.

  The chemical conversion treatment layer 12a is made of metal by chromium-based chemical conversion treatment such as chromate chromate treatment, phosphoric acid chromate treatment, and coating-type chromate treatment, or non-chromium (coating-type) chemical conversion treatment such as zirconium, titanium, and zinc phosphate. Although it is formed on the surface of the foil layer 12, it is firmly bonded to the fluororesin, the point that it can be continuously processed and the 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.

  Next, the thermal adhesive resin layer 15 will be described. The innermost heat-adhesive resin layer 15 is sandwiched and thermally bonded with the metal terminals of the lithium battery main body 122 protruding outward. At this time, the type of propylene constituting the thermal adhesive resin layer 15 differs depending on whether or not a metal terminal sealing adhesive film having metal adhesiveness is interposed between the thermal adhesive resin layer 15 and the metal terminal. 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, graft modification with unsaturated carboxylic acid is performed. It is necessary to use a film made of the acid-modified olefin resin.

  Polypropylene is suitably used as the heat-adhesive resin layer 15, but a single layer or a multilayer of linear low density polyethylene or medium density polyethylene, or a single resin composed of a blend resin of linear low density polyethylene and medium density polyethylene. Films consisting of layers or multilayers can also be used. Polypropylene can be classified into random propylene, homopropylene, block propylene and the like.

  Each of the above types of polypropylene, ie, random polypropylene, homopolypropylene, and block polypropylene, includes a low crystalline ethylene-butene copolymer, a low crystalline propylene-butene copolymer, and a three-component copolymer of ethylene, butene, and propylene. An antiblocking agent (AB agent) such as a polymer terpolymer, silica, zeolite, or acrylic resin beads, a fatty acid amide slip agent, or the like may be added.

  Further, the heat-adhesive resin layer 15 according to the present invention may be multilayered by combining the above-mentioned types of polypropylene layers as appropriate.

  Next, the acid-modified polyolefin layer 14 will be described. The acid-modified polyolefin layer 14 is a layer provided for bonding the metal foil layer 12 and the heat-adhesive resin layer 15. The acid-modified polyolefin layer 14 needs to be appropriately selected depending on the resin type used for the heat-adhesive resin layer 15. Modified polyolefin resins can be used, such as polyolefin resins graft-modified with unsaturated carboxylic acids, copolymers of ethylene or propylene and acrylic acid, or methacrylic acid, or metal-crosslinked polyolefin resins. 5% or more of a butene component, an ethylene-propylene-butene copolymer, an amorphous ethylene-propylene copolymer, a propylene-α-olefin copolymer, etc. may be added.

  Moreover, the acid-modified polyolefin layer 14 can provide the packaging material 10 for electrochemical cells excellent in content resistance and adhesive strength by using acid-modified polypropylene.

When using acid-modified polypropylene,
(1) Bigat softening point of 115 ° C or higher and melting point of 150 ° C or higher,
(2) Copolymer with 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 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. For example, an identification mark from any one of the constituent elements of the mat varnish layer, the colored stretched nylon film, the colored adhesive layer 13, the metal foil layer 12 on which the unevenness is formed, or a combination of all. It may be formed. By these combinations, it is possible to form a complicated design that is more difficult to counterfeit.

  In the present embodiment, the acid-modified polyolefin layer 14 is provided between the metal foil layer 12 and the heat-adhesive resin layer 15, but the embodiment in which the acid-modified polyolefin layer 14 is not provided is also within the technical scope of the present invention. included. Specifically, an adhesive layer other than an acid-modified polyolefin resin is interposed between the metal foil layer 12 and the heat-adhesive resin layer 15, and an acid-modified polyolefin resin is used for the heat-adhesive resin layer 15. And those obtained by heat laminating the laminated metal foil layer 12 and the heat-adhesive resin layer 15 and the like.

Hereinafter, the operation and effect of the present invention will be specifically described with reference to examples. Example 1 evaluates the molding process suitability and the laminar strength of the packaging material for electrochemical cells. In this experiment, the coloring added to the adhesive layer in order to confirm the molding process suitability and the laminar strength of the packaging material for electrochemical cells when a coloring pigment is added to the adhesive layer constituting the packaging material for electrochemical cells. Comparison was made using a packaging material for an electrochemical cell produced by changing the amount of pigment added.
[Packaging sample preparation]

  Both sides of aluminum (thickness 40 μm) are subjected to chemical conversion treatment, and one of the chemical conversion treatment surfaces is provided with a stretched nylon film (thickness 25 μm) through a polyester adhesive so that the adhesive layer has a thickness of about 4 μm. Bonded by dry lamination method, melt-extruded acid-modified polypropylene (thickness 23 μm) on the other chemical conversion treatment surface and laminated a sealant film made of polypropylene film (thickness 23 μm), and stretched nylon film / polyester adhesive A packaging material for an electrochemical cell composed of an agent / aluminum / acid-modified polypropylene / polypropylene film subjected to double-sided chemical conversion treatment was obtained.

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).

  Polyester adhesives include titanium oxide as a color pigment in solid content of 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 40 wt%, 50 Using the adhesive added by weight%, the obtained packaging materials for electrochemical cells were designated as Sample 1 to Sample 9, respectively. Samples 2 to 9 are electrochemical cell packaging materials according to the present invention.

  Next, in the packaging material obtained by the above method, instead of adding the color pigment to the polyester-based adhesive, 15% by weight of titanium oxide solid content was added as a color pigment to one surface of the stretched nylon film (thickness 25 μm). A comparative example consisting of a stretched nylon film / printing layer / polyester adhesive / aluminum / acid-modified polypropylene / polypropylene film subjected to a double-sided chemical conversion treatment after forming a printing layer (thickness 2 μm) with urethane-based ink A packaging material for an electrochemical cell was obtained.

[Evaluation of formability]
Samples 1 to 9 produced by the above method and the electrochemical cell packaging material according to the comparative example were cut to produce a 120 × 80 mm strip, a 55 × 32 mm rectangular male mold and the male mold Using a straight mold consisting of a female mold with a clearance of 0.3 mm (male corner R: 2 mm, ridge line R: 1 mm), a strip on the female mold so that the thermal adhesive resin layer is located on the male mold side Place the strip and press the strip with a pressing pressure (surface pressure) of 0.16 MPa, cold press molding to a molding depth of 6 mm on the packaging material for electrochemical cells according to Sample 1 to Sample 9 and Comparative Example did. Thereby, the packaging material for electrochemical cells according to Sample 1 to Sample 9 and the comparative example is a molded container (tray) having a depth of 6 mm and a rectangular recess having a size of 55 × 32 mm and a flange at the four peripheral edges of the recess. did.

  Next, strips having the same size as the outer periphery of the tray were separately prepared, the recesses were covered so that the flange portions substantially coincided, and the two peripheral edges of the recesses were heat-sealed with a width of 7 mm. The heat sealing at this time was carried out under the conditions of a sealing temperature of 190 ° C., a surface pressure of 1 MPa, and a sealing time of 3.0 seconds using hot plates coated with fluororesin on the top and bottom. Table 1 shows the evaluation of the presence or absence of interfacial delamination or floating or wrinkles at the site where the 7 mm wide heat seals intersect. Table 1 also shows the evaluation of the color of the appearance of the coloring pigment that can be recognized from the stretched nylon film side of the packaging material for electrochemical cells.

[Evaluation by measuring laminate strength]
Next, each of the produced packaging materials is cut into strips having a width of 15 mm, and a tension machine (AGS-50D, manufactured by Shimadzu Corporation) is used between the base material layer, which is the outermost layer of the laminated packaging material for electrochemical cells, and aluminum. (Product name)) was pulled at a speed of 50 mm / min, and the laminate strength was measured, and this value was defined as the anti-electrolytic solution laminate strength. The unit is N / 15 mm width. Table 1 shows the laminate strength measured for the packaging materials for electrochemical cells according to Sample 1 to Sample 9 and the comparative example.

  As shown in Table 1 above, as a result of comparing Sample 1 to Sample 9 and Comparative Example, it was found that Sample 1 to Sample 7 showed good moldability. Specifically, when 40% or more of a color pigment is added to the adhesive as shown in Sample 8 and Sample 9, and when a printing layer composed of ink is provided as shown in Comparative Example 1, delamination or The occurrence of wrinkles was observed (×). On the other hand, in samples 1 to 7, no delamination or wrinkle was observed (◯).

  When the color pigment added in sample 2 was 5%, the adhesive was not sufficiently colored, and it was difficult to distinguish the color from the outside (Δ), whereas the color pigment added in sample 3 to sample 9 In the case of 10% or more, the adhesive was colored and could be identified from the outside (◯).

  Samples 2 to 6 do not float and have the same laminating strength as sample 1. Sample 7 does not float, but a decrease in the strength of the laminate is observed.

  From the above, the electrochemical cell packaging material composed of 10% to 30% of titanium oxide added as a color pigment can be recognized from the outside, and functions as an identification mark that is difficult to counterfeit. In addition, it has been found that delamination does not occur due to heat applied to the sealing process after molding, and no floats or wrinkles occur.

10, 110, 210 Packaging material for electrochemical cells 11, 111 Base layer 12, 112 Metal foil layer 12a, 112a Chemical conversion layer 13, 113 Adhesive layer 14, 114 Acid-modified polyolefin layer 15, 115 Thermal adhesive resin layer 16, 116 Resin coating layer 17, 117 Adhesive layer
119 Print layer
120 exterior body
120a tray
120b sheet
121 Lithium-ion battery
122 Lithium-ion battery body

Claims (9)

Containing an electrochemical cell body comprising a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode;
A packaging material for an electrochemical cell that seals the electrochemical cell body by heat-sealing a peripheral edge,
At least a multilayer film having a structure in which a base material layer, an adhesive layer, a metal foil layer, and a heat-adhesive resin layer are laminated in this order,
A packaging material for electrochemical cells, wherein any one of the base material layer, the adhesive layer, and the metal foil layer contains an identification mark.   The packaging material for an electrochemical cell according to claim 1, wherein the identification mark is made of a pigment contained in the adhesive layer.   The packaging material for an electrochemical cell according to claim 1, wherein the identification mark is made of a pigment contained in a stretched nylon film constituting the base material layer.   The packaging material for an electrochemical cell according to claim 1, wherein the identification mark is constituted by unevenness provided on a surface of the metal foil constituting the metal foil layer.   The packaging material for an electrochemical cell according to claim 2 or 3, wherein the pigment is a pearl pigment.   The packaging material for an electrochemical cell according to claim 2 or 3, wherein the pigment is a fluorescent pigment.   The packaging material for an electrochemical cell according to any one of claims 2 to 6, wherein a mat varnish layer is formed on an upper surface of the base material layer.   The packaging material for an electrochemical cell according to any one of claims 2 to 6, wherein the base material layer is composed of a stretched nylon film whose surface is matted.   The packaging material for an electrochemical cell according to any one of claims 1 to 8, wherein an acid-modified polyolefin layer is interposed between the metal foil layer and the thermal adhesive resin layer.

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