JP2006156334A - Packing material for battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packing material for a battery capable of preventing occurrence of molding defects such as a crease in the packing material, and a pinhole or a crack in aluminum, excelling in moldability, and capable of preventing deposition or bleed out of a slip agent, degradation of slidability or the like in processes from the manufacturing of a packing material as the packing material for a battery to completion of the battery. <P>SOLUTION: This packing material for a battery is provided with at least a base material layer, aluminum foil, a chemical conversion treatment layer and a thermally-adhesive resin layer. The packing material for a battery is so structured that a surface layer formed of a polydimethylsiloxane-based block copolymer manufactured by copolymerizing a vinyl copolymer by using, as an initiator, azo group-containing polydimethylsiloxane amide is formed on a surface of the base material layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a battery packaging material excellent in sealing performance, moisture resistance, content resistance and moldability used as an exterior body of a secondary battery, particularly a lithium battery having an electrolyte (liquid or solid electrolyte). .

  A lithium battery is also called a lithium secondary battery, which is a battery made of a solid polymer, a gel polymer, a liquid, etc. as an electrolyte, and that generates electricity by the movement of lithium ions. It includes what consists of. The structure of the lithium secondary battery is as follows: positive electrode current collector (aluminum) / positive electrode active material layer (polymeric positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / electrolyte (propylene carbonate, ethylene Carbonate electrolyte such as carbonate, dimethyl carbonate, ethylene methyl carbonate, inorganic solid electrolyte composed of lithium salt, gel electrolyte) / negative electrode active substance layer (lithium metal, alloy, carbon, electrolyte, polymer negative electrode material such as polyacrylonitrile) ) / A lithium battery main body made of a negative electrode current collector (copper) and an outer package for packaging them. Lithium secondary batteries are widely used in electronic devices and electronic components, particularly mobile phones, notebook computers, video cameras and the like because of their high volumetric efficiency and weight efficiency.

  The lithium battery outer package is roughly divided into a cylindrical or rectangular parallelepiped metal can sealed by metal bonding and a flexible packaging material thermally bonded and sealed. Easy to take out, seal, or have flexibility, it can be shaped to fit the appropriate space of electronic equipment and electronic parts, and the shape of electronic equipment and electronic parts themselves can be designed to some extent freely Therefore, a packaging material in which a barrier layer made of a metal foil or the like typified by plastic film or aluminum is used for reasons such as further miniaturization and weight reduction can be used. It has become.

  The packaging material has physical properties required for a lithium battery, that is, moisture resistance, sealing property, puncture resistance, insulating property, heat / cold resistance, electrolytic solution resistance, corrosion resistance (electrolyte degradation and hydrolysis). As the packaging material is required to have puncture resistance and a base material layer for preventing external energization and moisture proofness, etc., the resistance to hydrofluoric acid generated by decomposition is required. In general, a laminate composed of a barrier layer made of a metal foil or the like typified by aluminum and an inner layer for ensuring hermeticity is used.

  As a form of the lithium battery, the above-described packaging material is formed into a bag shape as shown in FIG. 2 (a) at the peripheral heat-bonding portion [FIG. 2 (a) is a pillow type packaging bag, but three-way (It may be a packaging bag of type, four-way type, etc.), and although not shown, the lithium battery main body is stored with the metal terminals connected to each of the positive electrode and the negative electrode protruding outward, and the opening The bag type shown in FIG. 2 (b) that is thermally bonded and sealed, or the above packaging material is press-molded as shown in FIG. 3 (a) to form a recess, and this recess is not shown in the figure. The lithium battery main body is housed with the metal terminals connected to each of the positive electrode and the negative electrode protruding outward, and the recess is covered with the sheet-like packaging material prepared separately (not shown). Seal the four edges by heat bonding It was there is a molding type shown in FIG. 3 (b). In addition, although not shown in the figure, the four peripheral edges are thermally bonded using a press-molded one as shown in FIG. 3 (a) instead of the sheet-like packaging material covering the recess. There is also a molding type in which recesses are formed on both sides sealed. 2 and 3 are forms of the lithium battery of the present invention. 2 and 3, reference numeral 1 indicates a packaging material, reference numeral D indicates a lithium battery, reference numeral S indicates a peripheral thermal bonding portion, and T indicates a metal terminal.

  By the way, in the case of the above-described molding type lithium battery, the packaging material is inserted and pressed between the female mold and the male mold so that the inner layer is located on the male mold side. When the female mold and the base material layer of the packaging material are poorly slipped, the packaging material in which the recesses are formed is made of defects such as wrinkles due to poor sliding, or, in extreme cases, a metal foil represented by aluminum. There was a problem of poor molding such as pinholes and cracks in the barrier layer. The present applicant has previously proposed a packaging material provided with a coating film or a resin layer having excellent slipperiness on the surface of the base material layer as an improvement in the problem of molding defects occurring at the time of press molding (for example, , See Patent Document 1).

The packaging material of Patent Document 1 is a surface layer obtained by applying a fatty acid amide slip agent to the surface of a base material layer, or a fluororesin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, and a blend thereof. The packaging material thus configured improves the slipping property of the base material layer of the packaging material with respect to the female mold at the time of press molding, and the packaging material is represented by wrinkles and aluminum. Although it was possible to prevent molding defects such as pinholes and cracks in the barrier layer made of such a metal foil, the surface layer made of a fatty acid amide-based slip agent is most likely to improve the slipperiness. When the molding is continuously performed, the slip agent adheres to and accumulates on the molding die, the guide roll, etc., and the moldability deteriorates with time and the slip agent accumulates on the molded product. The fluororesin layer and silicone resin layer need to be baked at a high temperature in order to obtain a stable coating film, and an excessive heat history is applied to the base material layer. For example, sagging may occur and the moldability may be deteriorated, or the yield may be reduced. Polyester and acrylic resin layers are less effective in improving slipperiness when polyester or acrylic resin alone is used. There are cases where it is formed by blending an acrylic resin with a silicone (a polymer compound having a siloxane bond as a skeleton and various organic groups bonded to a silicon atom), but the silicone bleeds on the surface, which is the inner layer. There is a risk that it will fall to the surface and hinder the thermal adhesiveness of the inner layer, and even if it is a copolymer with silicone, it is difficult to express slipping. Or the remaining silicone component may be transferred to the inner layer surface (it may be transferred to the inner layer surface), which may impair the thermal adhesiveness of the inner layer. The process from the production of the packaging material to the battery as a battery packaging material However, there were various problems as described above.
JP 2002-216713 A

  Therefore, the present invention is free from the above-mentioned problems and is required for battery packaging materials such as moisture proof, sealing, puncture resistance, insulation, heat / cold resistance, electrolytic solution resistance, and corrosion resistance. In addition to being excellent in various physical properties, in particular, it is to provide a battery packaging material excellent in moldability in which molding defects such as wrinkles and aluminum, pinholes, cracks and the like do not occur in the packaging material. It is an object of the present invention to provide a battery packaging material free from slip agent accumulation, bleed-out, slippage deterioration, and the like in the process from the production of the packaging material to the battery as a battery packaging material.

  In order to achieve the above object, the inventor of the present invention according to claim 1 is a battery packaging material including at least a base material layer, an aluminum foil, a chemical conversion treatment layer, and a thermal adhesive resin layer, A surface layer comprising a polydimethylsiloxane block copolymer produced by copolymerizing a vinyl copolymer with an azo group-containing polydimethylsiloxane amide as an initiator is provided on the surface of the base material layer. It is a feature.

  The battery packaging material of the present invention is excellent in various physical properties required for the battery packaging material by adopting the above-mentioned means, and in particular, molding defects such as wrinkles in the packaging material, pinholes, cracks, etc. in the aluminum foil occur. And has excellent effects as a molded battery packaging material. In addition, the battery packaging material of the present invention has an excellent effect that there is no accumulation of slip agent, bleed out, reduction in slipperiness, etc. in the process from the production of the packaging material to the battery. Furthermore, the battery packaging material of the present invention also exhibits an excellent electrolytic solution resistance effect that it is difficult to dissolve even if the electrolytic solution adheres to the surface.

The present invention will be described in detail below with reference to the drawings.
FIG. 1 is a diagram schematically showing a basic layer structure of a battery packaging material according to the present invention. The battery packaging material 1 includes a surface layer 2, a base material layer 3, an adhesive layer 4, and a chemical conversion treatment. The layer 5, the aluminum foil 6, the chemical conversion treatment layer 5, and the thermal adhesive resin layer 7 are sequentially laminated. The battery packaging material 1 configured as described above is improved in the sliding property between the female mold of the molding die and the base material layer 3 of the battery packaging material 1 due to the effect of the surface layer 2. No wrinkle is generated on the aluminum foil 1, and no pinholes or cracks are generated on the aluminum foil 5.

Next, each layer constituting the battery packaging material 1 will be described. First, the surface layer 2 will be described. The surface layer 2 is a layer made of a polydimethylsiloxane block copolymer produced by copolymerizing a vinyl copolymer using azo group-containing polydimethylsiloxane amide as an initiator. 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 1),

a ² is a vinyl polymer portion. First, a polymer initiator method is applied to synthesize the polydimethylsiloxane block copolymer. In the polymer initiator method, for example, a polymer azo initiator (azo group-containing polydimethylsiloxane amide) into which a polydimethylsiloxane moiety represented by the following formula (Chemical Formula 2) is introduced is used. If a copolymerizable vinyl monomer is copolymerized using a molecular initiator, a block copolymer can be produced efficiently.

  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 3) and (Chemical Formula 4):

Here, m, n, n ′ and l are integers of 1 or more, M ₁ is a macromonomer represented by the following formulas (Chemical Formula 5) and (Chemical Formula 6),

Here, M ₂ is a vinyl monomer copolymerizable with M ₁ , and, for example, R can be represented by the following formula (Formula 7).

などである。

Etc.

  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) acrylates such as stearyl (meth) acrylate and lauryl (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, fluorine Halogen-containing monomers such as vinylidene chloride, olefins such as ethylene, propylene and isoprene, dienes such as chloroprene and butadiene, acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, crotonic acid, atropic acid, Α, β-unsaturated carboxylic acids such as citraconic acid, acrylamides such as acrylamide, methacrylamide, N, N-methylol acrylamide, N, N-dimethylacrylamide, diacetone acrylamide, methyl acrylamide glycolate methyl ether, N, N -Jimee Amino group-containing monomers such as ruaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and epoxy groups such as glycidyl (meth) acrylate and glycidyl allyl ether Containing monomer, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, allyl alcohol, Cardura E and acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, etc. And other vinyl monomers having hydrolyzable silyl groups include γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropyltrimethyl. Silane coupling agents such as toxisilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethoxyethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane can be used. it can. The above monomers may be used alone or in combination of two or more. In this paragraph, (meth) acrylate is used to mean 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 in the content, 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.

As the surface layer 2, the base material layer is formed by a known coating method such as a roll coating method or a gravure coating method using a resin liquid containing the polydimethylsiloxane block copolymer obtained by the polymerization reaction in a solution. It can obtain by apply | coating to the surface of 3 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.

  In addition, the base layer 3 is provided for the purpose of protecting the aluminum foil 6 described later and improving the puncture resistance against puncture from the outside, and is biaxial from the viewpoint of excellent mechanical strength. Polyester films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polycarbonate stretched in the same manner, polyamide films such as nylon 6, nylon 6,6, nylon 6,10, etc., or laminates thereof Can be mentioned. The thickness of the base material layer 3 is 6 μm or more, preferably 12 μm or more, and 25 μm or less. If the thickness is less than 6 μm, there may be pinholes in itself, and the protective effect of the aluminum foil 6 against external force is inferior, so that pinholes and cracks are likely to occur during molding, and molding defects are likely to occur. Further, whether the base material layer 3 is a single layer or a multi-layer, when the thickness exceeds 25 μm, no significant effect is recognized in terms of protection of the aluminum foil 5 against external force, and the volume and weight energy density are reduced. It is desirable not to use it from the viewpoint of cost-effectiveness. In addition, the above-described biaxially stretched film can be subjected to appropriate easy-adhesion treatment such as corona discharge treatment, ozone treatment, and plasma treatment on a necessary surface.

  Next, the aluminum foil 6 will be described. The aluminum foil 6 is provided to prevent water vapor from entering the inside of the battery from the outside. The aluminum foil 6 has a thickness of 20 to 80 μm in view of ensuring the water vapor barrier property and processing suitability during processing. That is appropriate. If the thickness is less than 20 μm, the pinhole of the aluminum foil alone is concerned and the risk of water vapor intrusion increases, and if it exceeds 80 μm, no significant effect is observed on the pinhole of the aluminum foil, and the water vapor barrier property is further improved. It is desirable that the effect cannot be expected, and conversely, the volume and weight energy density are reduced and not used from the viewpoint of cost effectiveness.

  In addition, the aluminum foil 6 contains 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight of iron, and has excellent extensibility as compared with the one not containing iron and is resistant to bending. There is little generation of pinholes, and a uniform molded product with no uneven thickness can be obtained particularly during molding. If the iron content is less than 0.3% by weight, no effect is observed in the prevention of pinholes and spreadability, and if it exceeds 9.0% by weight, the flexibility as an aluminum foil is hindered and the moldability is reduced. To do.

  Although the aluminum foil 6 is manufactured by cold rolling, its flexibility, waist strength and hardness change under annealing (so-called annealing treatment) conditions, but the aluminum foil used in the present invention is annealed. An aluminum foil that tends to be softer than the hard-treated product that has been annealed to some degree or completely is preferable.

  Next, the chemical conversion treatment layer 5 will be described. The chemical conversion treatment layer 5 is formed on both surfaces of the aluminum foil 6. The chemical conversion treatment layer 5 firmly adheres the aluminum foil 6 and the base material layer 3 and the aluminum foil 6 and the heat-adhesive resin layer 7 to prevent delamination during press molding and an electrolyte solution, or In order to prevent delamination between the aluminum foil 6 and the heat-adhesive resin layer 7 due to hydrofluoric acid generated by hydrolysis of the electrolytic solution. The chemical conversion treatment layer 5 is formed 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 both surfaces of the aluminum foil 6, it is firmly bonded to the base material layer 3 and the thermoadhesive resin layer 7, and it can be continuously treated and does not require a water washing step. In view of the fact that the processing cost can be reduced, it is most preferable to perform the coating type chemical conversion treatment, particularly with a treatment liquid containing an aminated phenol polymer, a trivalent chromium compound and a phosphorus compound as a phenol resin.

First, an aminated phenol polymer as a phenol resin 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 8), (Chemical Formula 9), (Chemical Formula 10), and (Chemical Formula 11). 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 8) to (Chemical Formula 11), 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 8) to (Chemical Formula 11), 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 8) and (Chemical Formula 10) 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 polymerizing a phenol compound or naphthol compound and formaldehyde to produce a polymer comprising repeating units represented by the following (Chemical Formula 8) to (Chemical Formula 10). 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.

And as the said chemical conversion treatment layer 5 formed using the processing liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound, about 1 to about 200 mg of aminated phenol polymers per 1 m < ² >. It is appropriate that the trivalent chromium compound is contained in a proportion of about 0.5 to about 50 mg in terms of chromium, and the phosphorus compound is contained in a proportion of about 0.5 to about 50 mg in terms of phosphorus. Is preferably about 5.0 to 150 mg, the trivalent chromium compound is contained in a proportion of about 1.0 to about 40 mg in terms of chromium, and the phosphorus compound is contained in a proportion of about 1.0 to about 40 mg in terms of phosphorus. . 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 the said chemical conversion treatment layer 5, what is necessary is just to select the well-known coating methods, such as a bar coating method, a roll coating method, a gravure coating method, and an immersion method, suitably for the said process liquid. The surface of the aluminum foil 6 that forms the chemical conversion treatment layer 5 is previously formed by a known degreasing treatment method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, or the like. It is preferable to perform the treatment from the viewpoint that the function of the chemical conversion treatment layer 5 can be maximized and can be maintained for a long time.

  Next, the thermal adhesive resin layer 7 will be described. As the thermoadhesive resin layer 7, when the metal terminal T (see FIGS. 2 and 3) connected to each of the positive electrode and the negative electrode of the lithium battery main body is sandwiched in a state of protruding outward and is thermally bonded and sealed. The type of resin differs depending on whether or not a metal terminal portion sealing adhesive film is interposed between the thermal adhesive resin layer 7 and the metal terminal T. When interposing an adhesive film for sealing metal terminals, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, ethylene-butene copolymers and other ethylene-based resins, homopolypropylene, ethylene- General polyolefin resin (linear or branched olefin resin consisting of carbon and hydrogen) such as propylene resin or propylene resin such as propylene copolymer or ethylene-propylene-butene copolymer as appropriate. In the case where the adhesive film for sealing the metal terminal portion is not interposed, an acid-modified polyolefin resin, for example, a polyolefin resin graft-modified with an unsaturated carboxylic acid, ethylene or propylene and acrylic acid, Or an acid-modified polyolefin such as a copolymer with methacrylic acid Down resin, particularly preferably it may be used a graft modified polyolefin resin with an unsaturated carboxylic acid. This is because a polyolefin resin graft-modified with an unsaturated carboxylic acid is superior in heat resistance compared to an acid-modified polyolefin resin such as a copolymer of ethylene or propylene and acrylic acid or methacrylic acid. The heat-adhesive resin layer 7 is not limited to a single layer made of the above general polyolefin resin or acid-modified polyolefin resin, but is a general polyolefin resin layer / acid-modified polyolefin resin layer (innermost layer), acid-modified 2 to 3 layers represented by polyolefin resin layer / general polyolefin resin layer (innermost layer), acid-modified polyolefin resin layer / general polyolefin resin layer / acid-modified polyolefin resin layer (innermost layer), etc. It may be a layer. As a method for forming the heat-adhesive resin layer 7, a general polyolefin resin or an acid-modified polyolefin resin formed into a film is laminated on the surface of the chemical conversion treatment layer 5 of the aluminum foil 6 by a thermal lamination method. Or formed by pelletizing a general polyolefin-based resin or acid-modified polyolefin-based resin by heating and melting and extruding the surface of the chemical conversion treatment layer 5 of the aluminum foil 6 It is. The thickness of the heat-adhesive resin layer 7 is 10 to 100 μm, preferably 30 to 50 μm. If the thickness is less than 10 μm, sufficient adhesive strength cannot be obtained when heat-bonding, resulting in a problem in sealing performance. If the thickness exceeds 100 μm, there is no significant effect on the sealing performance when heat-adhering and sealing, and the total thickness increases to reduce the volume and weight energy density and cost-effectiveness. It is preferable not to use from the viewpoint.

  In addition, as said adhesive bond layer 4 which bonds the said base material layer 3 and the said chemical conversion treatment layer 5 surface of the said aluminum foil 6, it is for well-known dry lamination, such as a polyester type, a polyether type, a polyurethane type, for example What is necessary is just to laminate | stack by the dry lamination method using an adhesive agent.

  Next, the present invention will be described in detail with reference to examples.

First, one side of an aluminum foil (thickness 40 μm) in which a chemical conversion treatment layer is formed on both surfaces by chemical conversion treatment on both sides with a chemical conversion treatment liquid containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound in advance. A surface and a 25 μm-thick biaxially stretched nylon film (hereinafter referred to as an ON film) as a base material layer are laminated via a two-component curable polyurethane adhesive and the aluminum foil (40 μm thickness) On the other surface, a 30 μm thick unstretched polypropylene film (hereinafter referred to as CPP) as a heat-adhesive resin layer is heated so that the surface of the chemical conversion treatment layer becomes 120 ° C. and bonded by a thermal lamination method, The pasted product was reheated to 180 ° C. to produce a packaging material. Thereafter, a resin solution comprising a polydimethylsiloxane block copolymer is diluted with methyl ethyl ketone on the ON surface of the packaging material, and applied by a roll coating method so that the coating amount after drying is 0.15 g / m ^2. Thus, a battery packaging material of the present invention having a surface layer formed on the ON surface was obtained. The battery packaging material has the following structure: surface layer / ON 25 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 40 μm / chemical conversion treatment layer / CPP 30 μm.

  A battery packaging material of the present invention was obtained in the same manner as in Example 1 except that a 15 μm thick ON film was used instead of the 25 μm thick ON film. The battery packaging material has the following structure: surface layer / ON 15 μm / adhesive layer / chemical conversion layer / aluminum foil 40 μm / chemical conversion layer / CPP 30 μm.

  Instead of the 25 μm-thick ON film, a 9 μm-thick biaxially stretched polyethylene terephthalate film (hereinafter referred to as PET film) and a 15 μm-thick ON film were laminated via a two-component curable polyurethane adhesive. A battery packaging material of the present invention was obtained in the same manner as in Example 1 except that the laminate was used. The structure of the battery packaging material is: surface layer / PET 9 μm / adhesive layer / ON 15 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 40 μm / chemical conversion treatment layer / CPP 30 μm.

  A battery packaging material of the present invention was obtained in the same manner as in Example 2 except that a 35 μm thick aluminum foil was used instead of the 40 μm thick aluminum foil. The battery packaging material has the following structure: surface layer / ON 15 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 35 μm / chemical conversion treatment layer / CPP 30 μm.

[Comparative Example 1]
In Example 1, a battery packaging material having no surface layer was used as a comparative example. The structure of this battery packaging material is ON 25 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 40 μm / chemical conversion treatment layer / CPP 30 μm.

[Comparative Example 2]
In Example 2, a battery packaging material having no surface layer was used as a comparative example. The configuration of the battery packaging material is ON 15 μm / adhesive layer / chemical conversion layer / aluminum foil 40 μm / chemical conversion layer / CPP 30 μm.

[Comparative Example 3]
In Example 3, a battery packaging material having no surface layer was used as a comparative example. The configuration of the battery packaging material is PET 9 μm / adhesive layer / ON 15 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 40 μm / chemical conversion treatment layer / CPP 30 μm.

[Comparative Example 4]
In the same manner as in Example 1 except that a surface layer was formed by applying erucic acid amide (slip agent) to 40 mg / m ² after drying instead of the resin solution comprising the polydimethylsiloxane block copolymer. A battery packaging material as a comparative example was obtained. The structure of the battery packaging material is: surface layer (erucic acid amide) / ON 25 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 40 μm / chemical conversion treatment layer / CPP 30 μm.

[Comparative Example 5]
In Example 4, a battery packaging material having no surface layer was used as a comparative example. The structure of this battery packaging material is ON 15 μm / adhesive layer / chemical conversion treatment layer / aluminum foil 35 μm / chemical conversion treatment layer / CPP 30 μm.

  For the battery packaging materials of Examples 1 to 4 and Comparative Examples 1 to 5 prepared above, the moldability, the adhesion of a slip agent or the like that forms a surface layer to the molding die and the guide roll at the time of molding, The sliding properties over time, the heat sealability over time, and the electrolytic solution resistance of the packaging material surface were evaluated by the following evaluation methods, and the results are summarized in Tables 1 and 2.

〔Evaluation methods〕
* 1) Formability evaluation method:
After the battery packaging material is stored in a constant temperature and humidity chamber (40 ° C., 90% RH) for 14 days in a roll state, a sample cut into 80 × 120 mm square is molded into a molding die (female) with a 30 × 50 mm diameter. With a molding die (male) corresponding to this, the molding depth is changed from 0.5 mm in 0.5 mm increments, and each of the 10 samples is cold-molded, and the packaging material is made of straw or aluminum. The forming depth at which pinholes and cracks did not occur in any of the 10 samples in the foil was defined as the limit forming depth, and the forming depth was indicated as an evaluation value. For comparison, an evaluation value before storage is also shown.

* 2) Adhesion evaluation method for slip agents that form a surface layer on the molding die and guide roll during molding:
The molding die and guide roll are visually checked for the presence or absence of a slip agent or the like that forms a surface layer on the molding die and guide roll after 1000 shots are molded on a molding machine capable of continuous molding. Those in which no adhesion was observed were indicated as good by ◯, and those in which adhesion was observed were marked as poor by x.

* 3) Evaluation method of slipperiness over time:
After the battery packaging material was stored in a constant temperature and humidity chamber (40 ° C., 90% RH) for 14 days in a roll state, the dynamic friction coefficient of the outermost surface (ON surface or PET surface) was measured, and the measured value was shown. The measurement was performed with a Haydon-type measuring instrument [manufactured by Toshin Chemical Co., Ltd .: Haydon 14 (trade name)] under conditions of a load of 100 g and a friction speed of 100 mm / min. For comparison, the measured values before storage are also shown.

* 4) Evaluation method of heat sealability over time:
After storing the battery packaging material in a roll in a constant temperature and humidity chamber (40 ° C., 90% RH) for 14 days, a sample piece was cut into 30 × 70 mm squares, and the sample pieces were separated from each other on the CPP surfaces. Heat seal (sealing conditions: 190 ° C, 1.0 MPa, 3 seconds) with a heat-sealing machine consisting of 7 mm wide gold-gold upper and lower heat plates, and cut to 15 mm width, 30 mm between chucks, tensile It measured with the autograph [Shimadzu make: AGS-50D (brand name)] at a speed of 300 mm / min, and showed the measured value. The unit is N / 15 mm width. For comparison, the measured values before storage are also shown.

* 5) Method for evaluating electrolytic solution resistance on the surface of battery packaging materials:
Electrolytic solution [lithium hexafluorophosphate was dissolved in a mixed solution <ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (volume ratio)> to obtain a 1 mol / liter lithium hexafluorophosphate solution. The product was dripped 40 mg onto the surface of the battery packaging material, and after 30 seconds, the product wiped with a paper wiper was allowed to stand for 24 hours and visually checked for whitening of the surface. And those with whitening recognized as x were marked as defective.

  As is clear from Table 1, the battery packaging materials of Examples 1 to 4 are superior in slipperiness as compared with Comparative Examples 1 to 5, and the slipperiness before and after storage in the thermostatic chamber is not changed. Therefore, excellent results in moldability are shown, and since there is no adhesion of a slip agent or the like that forms a surface layer on the molding die and guide roll as compared with Comparative Example 4, cleaning of the die and guide roll is possible. This eliminates the need to increase productivity and prevents a slip agent or the like forming a surface layer from adhering to the molded product, thereby contributing to an improvement in yield. Further, Comparative Example 4 has a moldability after storage in a constant temperature and humidity chamber. On the other hand, in Examples 1 to 4, the decrease in moldability can be reduced even after storage in a constant temperature and humidity chamber. In addition to the effects described above, the present invention provides a battery packaging material in which the base material layer is an ON film as in Examples 1, 2, 4, and Comparative Examples 1, 2, 4, 5. When the electrolyte solution adheres to the surface of the material layer, in Comparative Examples 1, 2, 4, and 5, since the ON film is dissolved and whitened with the electrolyte solution, physical properties such as puncture resistance as the base material layer are reduced. On the other hand, since Examples 1, 2, and 4 have the effect of repelling the electrolytic solution, the ON film can be prevented from being dissolved by the electrolytic solution. Furthermore, in Example 4 and Comparative Example 5, the aluminum foil is thinner than the other Examples and Comparative Examples, but Example 4 provided with a surface layer can be formed deeper than Comparative Example 5. Therefore, the battery packaging material excellent in volume energy density and weight energy density can be obtained.

  In the examples, the battery packaging material in which the surface layer was formed on the surface of the base material layer after the packaging material was produced was shown. However, the surface layer provided in the battery packaging material of the present invention is a packaging material. Even if a battery packaging material is manufactured in the process shown in Example 1 after the surface layer is first provided on the base material layer in order to prevent settling in a roll state such as during the manufacturing process or during storage. By adopting such a manufacturing process (method), productivity can be improved and costs can be reduced. In the description so far, the thermal adhesive resin layer 7 has been described as being formed by a thermal lamination method. However, a known dry lamination adhesive such as polyester, polyether, or polyurethane is used. The heat-adhesive resin layer 7 may be laminated and formed by a dry lamination method.

It is a figure showing the basic layer composition of the packaging material for batteries concerning the present invention diagrammatically. It is a figure explaining one Example of the form of a lithium battery. It is a figure explaining the other Example of the form of a lithium battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery packaging material 2 Surface layer 3 Base material layer 4 Adhesive layer 5 Chemical conversion treatment layer 6 Aluminum foil 7 Thermal adhesive resin layer

Claims (1)

A battery packaging material comprising at least a base material layer, an aluminum foil, a chemical conversion treatment layer, and a heat-adhesive resin layer, the vinyl copolymer having an azo group-containing polydimethylsiloxane amide as an initiator on the surface of the base material layer A battery packaging material, comprising a surface layer made of a polydimethylsiloxane block copolymer produced by copolymerizing a polydimethylsiloxane block copolymer.

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