JP5652178B2 - Exterior materials for lithium-ion batteries - Google Patents

Description

  The present invention relates to a packaging material for a lithium ion battery.

  BACKGROUND ART Lithium ion batteries that can be made ultra-thin and miniaturized have been actively developed as batteries used in portable terminal devices such as personal computers and mobile phones, video cameras, and satellites. Lithium ion batteries are also attracting attention as batteries for hybrid vehicles, electric vehicles, and the like that have a low environmental impact.

Conventionally, metal cans have been used as exterior materials for lithium ion batteries (hereinafter simply referred to as “exterior materials”) that contain battery cells, electrolytes, and the like in lithium ion batteries. Multi-layer film (for example, a structure such as a heat-resistant substrate layer / aluminum foil layer / a heat-fusible film layer) from the advantages of high heat dissipation, low cost, and the ability to freely select the shape of the battery. An exterior material made of is widely used. Lithium-ion batteries that use outer packaging materials made of multilayer films must be heat sealed by containing the battery contents inside the outer packaging material in the form of a bag or in the state where recesses are formed by cold forming. Formed with.
A multilayer film used as an outer packaging material of a lithium ion battery is generally provided with an aluminum foil layer therein, and a battery using the multilayer film is called an aluminum laminate type lithium ion battery.

The electrolyte of the lithium ion battery is composed of an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and an electrolyte. Further, as a lithium salt that is an electrolyte, a salt such as LiPF ₆ or LiBF ₄ is used. However, these salts generate hydrofluoric acid by a hydrolysis reaction due to moisture, and may cause corrosion of the metal surface of the battery cell and a decrease in laminate strength between the layers of the multilayer film. In an aluminum laminate type lithium ion battery, an aluminum foil layer is provided on a multilayer film as an exterior material, thereby preventing moisture from entering the battery from the surface of the multilayer film.

On the other hand, the reason why the lithium ion battery can be miniaturized is that the energy density is high. The high energy density of a lithium ion battery is determined by the amount of battery cells and electrolyte contained in the battery, and the amount of inclusion depends on the molding depth when the exterior material is deep-drawn into a battery shape. In the deep drawing of an exterior material generally performed by a mold, if the molding depth is too deep, cracks and pinholes are generated in the stretched portion, and the reliability as a battery is lost. Therefore, it is important how to increase the energy density by increasing the molding depth while maintaining the reliability of the battery by suppressing cracks and pinholes.
Moreover, in the manufacture of lithium ion batteries, for quality control, a barcode is printed on the outer surface of the exterior material by a technique such as inkjet, and lot tracing is performed. Therefore, the exterior material is also required to have good barcode printability on the outer surface.

It is known that the formability of the exterior material is affected by the slipperiness of the exterior material with respect to the cold forming mold. Therefore, the following exterior materials (1) to (3) are shown as exterior materials with improved slipperiness.
(1) An exterior material in which the outer surface of a biaxially stretched polyester film layer that is a base material layer is subjected to silicone treatment, and the dynamic friction coefficient of the surface is 0.3 or less (Patent Document 1).
(2) A predetermined amount of slip agent is added to the film that forms the sealant layer, and after lamination during the production of the exterior material, the aging temperature and time are controlled to improve the adhesion performance with aluminum, An exterior material that has been bleed out to exhibit slipperiness (Patent Document 2).
(3) An exterior material obtained by coating or spraying a fatty acid amide-based slip agent on at least the surface of the base material layer (Patent Documents 3 and 4).

JP 2002-56824 A JP 2005-32456 A JP 2002-216713 A JP 2002-216714 A

  However, in the exterior materials (1) to (3), it is difficult to achieve both excellent formability and barcode printing properties.

  An object of this invention is to provide the exterior material for lithium ion batteries which has the outstanding moldability and favorable barcode printing property.

  As a result of intensive studies to solve the above problems, the present inventors have controlled the static friction coefficient (μs-A) of the base material layer and the static friction coefficient (μs-B) of the sealant layer within a specific range, It has been found that excellent moldability and good bar code printability can be obtained. The present invention employs the following configuration in order to solve the above problems.

[1] An exterior material for a lithium ion battery in which a first adhesive layer, an aluminum foil layer provided with a corrosion prevention treatment layer on at least one surface, a second adhesive layer, and a sealant layer are sequentially laminated on one surface of the base material layer. There,
The static friction coefficient (μs-A) of the outer surface of the base material layer is 0.1 to 0.25, and the static friction coefficient (μs-B) of the outer surface of the sealant layer is 0.1 to 0.5. der is, and the ratio of the static friction coefficient of the outer surface of the base layer coefficient of static friction of the outer surface of the (μs-a) and the sealant layer (μs-B) (μs- a / μs-B) is A packaging material for a lithium ion battery, characterized by being 0.8 to 1.2 .
[2 ] A slip agent was applied to the outer surface of the base material layer at a rate of 1 to 20 mg / m ² , and a slip agent was applied to the outer surface of the sealant layer at a rate of 1 to 20 mg / m ² . [1 ] A packaging material for a lithium ion battery according to [1 ] .
[ 3 ] The corrosion prevention treatment layer is a layer comprising a rare earth element-based oxide sol containing a mixture containing an anionic polymer and a crosslinking agent for crosslinking the anionic polymer, or a cationic polymer and the cationic The packaging material for a lithium ion battery according to [1] or [2] , which has a multilayer structure in which at least one of layers containing a mixture containing a crosslinking agent that crosslinks a polymer is laminated.

  The outer packaging material for a lithium ion battery of the present invention has both excellent moldability and good bar code printability.

It is sectional drawing which showed an example of the exterior material of this invention.

Hereinafter, an example of the exterior material of the present invention will be described in detail.
As shown in FIG. 1, a lithium ion battery exterior material 1 (hereinafter referred to as “exterior material 1”) of the present embodiment has a first adhesive layer 12, an aluminum foil layer on one surface of a base material layer 11. 13, a corrosion prevention treatment layer 14, a second adhesive layer 15, and a sealant layer 16 are sequentially laminated.

The exterior material 1 has a static friction coefficient (μs-A) of 0.1 to 0.25 on the outer surface of the base material layer 11, that is, the outermost surface when the battery is manufactured, and the outer surface of the sealant layer 16, that is, battery manufacturing. The static friction coefficient (μs-B) of the innermost surface at the time is 0.1 to 0.5.
If the static friction coefficient (μs-A) is 0.1 or more, it is easy to measure the static friction coefficient and control becomes easy. If the coefficient of static friction (μs-A) is 0.25 or less, the surface of the base material layer 11 is sufficiently slippery, and excellent moldability is obtained.
If the static friction coefficient (μs-B) is 0.1 or more, it is easy to measure the static friction coefficient and control becomes easy. When the coefficient of static friction (μs-B) is 0.5 or less, the slipperiness of the surface of the sealant layer 16 is sufficiently obtained, and excellent moldability is obtained.
In addition, the static friction coefficient in this invention is a static friction coefficient measured based on JIS-P8147.

  The ratio (μs-A / μs-B) of the static friction coefficient (μs-A) to the static friction coefficient (μs-B) in the exterior material 1 is preferably 0.33 to 2.4, and 0.8 to 1. 2 is more preferable. If the ratio (μs-A / μs-B) is within the above range, excellent moldability can be obtained.

  As a method of adjusting the static friction coefficient (μs-A) of the outermost surface and the static friction coefficient (μs-B) of the outermost surface in the exterior material 1, a method of applying a slip agent to the surface of the base material layer 11 or the sealant layer 16, Or the method of mix | blending a slip agent in the base material layer 11 or the sealant layer 16, and making it bleed out is preferable, and the method of apply | coating a slip agent to the surface of the base material layer 11 or the sealant layer 16 is more preferable.

Slip agents of the outer surface of the base layer 11 is preferably ^{1~20mg / m 2, 5~15mg / m} 2 is more preferable. When the amount of the slip agent on the surface of the base material layer 11 is equal to or greater than the lower limit of the above range, the static friction coefficient (μs-A) becomes smaller and sufficient slipperiness is easily obtained and the moldability is improved. If the amount of slip agent on the surface of the base material layer 11 is not more than the upper limit of the above range, the static friction coefficient (μs-A) on the surface of the base material layer 11 becomes larger and the bar code printability is improved.
Slip agents of the outer surface of the sealant layer 16 is preferably ^{1~20mg / m 2, 5~15mg / m} 2 is more preferable. When the amount of the slip agent on the surface of the sealant layer 16 is not more than the upper limit of the above range, the static friction coefficient (μs-B) becomes smaller and sufficient slipperiness is easily obtained, and the moldability is improved. If the amount of slip agent on the surface of the sealant layer 16 is equal to or less than the upper limit of the above range, process contamination can be easily suppressed.
The amount of slip agent on the surface of the base material layer 11 and the sealant layer 16 was determined by extracting the slip agent extracted into chloroform after performing an extraction operation with 5 mL of chloroform for a surface area of 94.985 cm ² . The amount was measured by GC-MS and calculated using a calibration curve prepared in advance.

(Base material layer 11)
The base material layer 11 provides heat resistance in a sealing process when manufacturing a lithium ion battery, and plays a role of suppressing generation of pinholes that may occur during processing and distribution.
Examples of the base material layer 11 include a layer made of a stretched or unstretched film of a polyester film, a polyamide film, or a polypropylene film. Especially, the layer which consists of a stretched polyamide film and a stretched polyester film from the point which improves a moldability, heat resistance, pinhole resistance, and insulation is preferable.
The base material layer 11 may be a single layer or a plurality of layers.

You may mix | blend additives, such as a slip agent and an antiblocking agent, with the base material layer 11. FIG.
Examples of the slip agent include fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylene bisoleic acid amide, and ethylene biserucic acid amide, silicone, and polymer wax.
As the antiblocking agent, those of various fillers such as silica are preferable.
A slip agent and an antiblocking agent may be used individually by 1 type, and may use 2 or more types together.

6-40 micrometers is preferable and, as for the thickness of the base material layer 11, 10-25 micrometers is more preferable. When the thickness of the base material layer 11 is 6 μm or more, heat resistance, pinhole resistance, and insulation are improved. If the thickness of the base material layer 11 is 40 micrometers or less, a moldability will improve. The said thickness is the whole thickness, when the base material layer 11 is a multilayer film.
Further, the strength properties of the film used as the base material layer 11 are not particularly limited.

(First adhesive layer)
The first adhesive layer 12 is a layer that adheres the base material layer 11 and the aluminum foil layer 13.
The adhesive constituting the first adhesive layer 12 includes a main component such as polyester polyol, polyether polyol, acrylic polyol, and polyolefin polyol, an aromatic or aliphatic bifunctional or higher isocyanate compound as a curing agent, or its A two-component curable polyurethane adhesive in which a polyisocyanate compound composed of an adduct body, a burette body or a trimer is allowed to act is preferable.
The thickness of the first adhesive layer 12 is preferably 1 to 10 μm and more preferably 3 to 7 μm from the viewpoints of adhesive strength, followability, workability, and the like.

(Aluminum foil layer)
As the aluminum foil layer 13, a general soft aluminum foil can be used, and further, an aluminum foil containing iron is preferably used from the viewpoint of imparting pinhole resistance and extensibility during molding.
0.1-9.0 mass% is preferable and, as for content of iron in aluminum foil (100 mass%), 0.5-2.0 mass% is more preferable. When the iron content is 0.1% by mass or more, pinhole resistance and spreadability are improved. If the iron content is 9.0% by mass or less, flexibility is improved.
The thickness of the aluminum foil layer 13 is preferably 9 to 200 μm and more preferably 15 to 100 μm from the viewpoint of barrier properties, pinhole resistance, and workability.

For the aluminum foil layer 13, it is preferable to use a degreased aluminum foil from the viewpoint of the resistance to electrolytic solution. The degreasing treatment is roughly classified into a wet type and a dry type.
Examples of the wet type degreasing treatment include acid degreasing and alkali degreasing.
Examples of the acid used for acid degreasing include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. These acids may be used individually by 1 type, and may use 2 or more types together. Moreover, you may mix | blend various metal salts used as supply sources, such as Fe ion and Ce ion, with these inorganic acids as needed from the point which the etching effect of aluminum foil improves.
As an alkali used for alkali degreasing, sodium hydroxide etc. are mentioned as a thing with a high etching effect, for example. Moreover, what mix | blended weak alkali type and surfactant is mentioned.
The wet type degreasing treatment is performed by an immersion method or a spray method.

As a dry type degreasing process, the method etc. which are performed at the process of annealing the aluminum etc. are mentioned, for example. In addition to the degreasing treatment, frame treatment, corona treatment, and the like can be given. Furthermore, a degreasing treatment in which pollutants are removed by oxidative decomposition with active oxygen generated by irradiating with ultraviolet rays having a specific wavelength is also included.
In the packaging material 1, the degreasing treatment of the aluminum foil layer 13 may be performed only on one side of the aluminum foil layer 13 or on both sides.

[Corrosion prevention treatment layer]
The corrosion prevention treatment layer 14 is basically a layer provided to prevent corrosion of the aluminum foil layer 13 due to the electrolytic solution or hydrofluoric acid. The corrosion prevention treatment layer 14 is formed by, for example, a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, a chemical conversion treatment, or a combination of these treatments.
Degreasing treatment includes acid degreasing or alkali degreasing. Examples of the acid degreasing include a method of using an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid alone or a mixture thereof. In addition, by using an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved in the inorganic acid as an acid degreasing, not only the degreasing effect of aluminum is obtained, but also the passive aluminum A fluoride can be formed, which is effective in terms of resistance to hydrofluoric acid. Examples of the alkaline degreasing include a method using sodium hydroxide or the like.
Examples of the hydrothermal modification treatment include boehmite treatment in which an aluminum foil is immersed in boiling water to which triethanolamine is added.
Examples of the anodizing treatment include alumite treatment.
Examples of the chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments composed of these mixed phases. .
When performing these hydrothermal modification treatment, anodizing treatment, and chemical conversion treatment, it is preferable to perform the degreasing treatment in advance.
The corrosion prevention treatment layer 14 may be a single layer or a multilayer.

  Among the above treatments, in particular, the hot water modification treatment and the anodizing treatment dissolve the aluminum foil surface with a treating agent to form an aluminum compound (boehmite, anodized) having excellent corrosion resistance. Therefore, since it becomes a form in which a co-continuous structure is formed from the aluminum foil layer 13 to the corrosion prevention treatment layer 14, it is included in the definition of the chemical conversion treatment, but is not included in the definition of the chemical conversion treatment as described later. It is also possible to form the corrosion prevention treatment layer 14 only by the technique. As the method, for example, a sol of a rare earth element-based oxide such as cerium oxide having an average particle size of 100 nm or less is used as a material that has an corrosion prevention effect (inhibitor effect) of aluminum and is also suitable from an environmental viewpoint. The method using is mentioned. By using this method, it is possible to impart a corrosion prevention effect to a metal foil such as an aluminum foil even with a general coating method.

Examples of the rare earth element-based oxide sol include sols using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents. Among these, an aqueous sol is preferable.
In order to stabilize the dispersion of the rare earth element-based oxide sol, an inorganic acid such as nitric acid, hydrochloric acid or phosphoric acid or a salt thereof, an organic acid such as acetic acid, malic acid, ascorbic acid or lactic acid is usually dispersed. Used as a stabilizer. Among these dispersion stabilizers, phosphoric acid, in particular, is improved in adhesion to the aluminum foil layer 13 using (1) dispersion stabilization of sol and (2) aluminum chelate ability of phosphoric acid in the exterior material 1. , (3) Electrolyte resistance imparted by capturing (passivation formation) aluminum ions eluted under the influence of hydrofluoric acid, (4) Corrosion prevention treatment layer 14 due to easy dehydration condensation of phosphoric acid even at low temperatures ( An improvement in the cohesive strength of the oxide layer) is expected.
Examples of the phosphoric acid or a salt thereof include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. Of these, condensed phosphoric acid such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and ultrametaphosphoric acid, or alkali metal salts and ammonium salts thereof are preferable for the functional expression in the exterior material 1. Considering the dry film-forming properties (drying capacity and heat quantity) when forming the corrosion prevention treatment layer 14 made of a rare earth oxide by various coating methods using the rare earth oxide sol, dehydration condensation at a low temperature. From the viewpoint of excellent properties, a sodium salt is more preferable. As the phosphate, a water-soluble salt is preferable.

  The mixing ratio of phosphoric acid (or a salt thereof) to cerium oxide is preferably 1 to 100 parts by mass with respect to 100 parts by mass of cerium oxide. If the said compounding ratio is 1 mass part or more with respect to 100 mass parts of cerium oxides, cerium oxide sol will become more stable and the function of the exterior material 1 will become more favorable. As for the said mixture ratio, 5 mass parts or more are more preferable with respect to 100 mass parts of cerium oxides. Moreover, if the said mixture ratio is 100 mass parts or less with respect to 100 mass parts of cerium oxides, it will be easy to suppress the functional fall of a cerium oxide sol. The blending ratio is more preferably 50 parts by mass or less, and further preferably 20 parts by mass or less, with respect to 100 parts by mass of cerium oxide.

Since the corrosion prevention treatment layer 14 formed of the rare earth oxide sol is an aggregate of inorganic particles, the cohesive force of the layer itself may be lowered even after a dry curing step. Therefore, the corrosion prevention treatment layer 14 in this case is preferably combined with the following anionic polymer or cationic polymer in order to supplement cohesion.
As an anionic polymer, the polymer which has a carboxy group is mentioned, For example, the copolymer which copolymerized poly (meth) acrylic acid (or its salt) or poly (meth) acrylic acid as a main component is mentioned.
The copolymer component of the copolymer includes an alkyl (meth) acrylate monomer (the alkyl group includes a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (alkyl groups include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy (meth) acrylamide, N, N-dialkoxy (Meth) acrylamide (as alkoxy group, methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N Amide group-containing monomers such as methylol (meth) acrylamide and N-phenyl (meth) acrylamide; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; glycidyl (meth) acrylate and allyl Glycidyl group-containing monomers such as glycidyl ether; Silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxylane; Isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate It is done.

  These anionic polymers play a role of improving the stability of the corrosion prevention treatment layer 14 (oxide layer) obtained using the rare earth element oxide sol. This is achieved by the effect of protecting the hard and brittle oxide layer with an acrylic resin component and the effect of capturing ionic contamination (particularly sodium ions) derived from phosphate contained in the rare earth oxide sol (cation catcher). Is done. That is, when an alkali metal ion such as sodium or alkaline earth metal ion is contained in the corrosion prevention treatment layer 14 obtained by using the rare earth element oxide sol, the corrosion prevention starts from the place containing the ion. The processing layer 14 is likely to deteriorate. Therefore, the resistance of the corrosion prevention treatment layer 14 is improved by fixing sodium ions and the like contained in the rare earth oxide sol by the anionic polymer.

The corrosion prevention treatment layer 14 combining an anionic polymer and a rare earth element oxide sol has the same corrosion prevention performance as the corrosion prevention treatment layer 14 formed by subjecting an aluminum foil to chromate treatment. The anionic polymer is preferably a structure in which a polyanionic polymer that is essentially water-soluble is crosslinked. As a crosslinking agent used for formation of this structure, the compound which has an isocyanate group, a glycidyl group, a carboxy group, and an oxazoline group is mentioned, for example.
Examples of the compound having an isocyanate group include tolylene diisocyanate, xylylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate, 4,4′diphenylmethane diisocyanate or a hydrogenated product thereof, diisocyanates such as isophorone diisocyanate; or these isocyanates. Polyisocyanates such as adducts obtained by reacting a polyhydric alcohol with a polyhydric alcohol such as trimethylolpropane, burette obtained by reacting with water, or isocyanurate as a trimer; Examples include blocked polyisocyanates obtained by blocking isocyanates with alcohols, lactams, oximes and the like.

Examples of the compound having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, Epoxy compounds in which epichlorohydrin is allowed to react with glycols such as neopentyl glycol; polyhydric alcohols such as glycerin, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol, and epoxy compounds in which epichlorohydrin is allowed to react; phthalic acid, terephthalate Examples thereof include an epoxy compound obtained by reacting a dicarboxylic acid such as acid, oxalic acid, or adipic acid with epichlorohydrin.
Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids. Further, poly (meth) acrylic acid or alkali (earth) metal salt of poly (meth) acrylic acid may be used.
As the compound having an oxazoline group, for example, a low molecular compound having two or more oxazoline units, or a polymerizable monomer such as isopropenyl oxazoline, (meth) acrylic acid, (meth) acrylic acid alkyl ester And those obtained by copolymerizing acrylic monomers such as hydroxyalkyl (meth) acrylate.

  Further, the anionic polymer may be selectively reacted with an amine and a functional group to form a siloxane bond at the crosslinking point, like a silane coupling agent. In this case, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ -Mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane and the like can be used. Of these, epoxy silane, amino silane, and isocyanate silane are preferable in consideration of reactivity with an anionic polymer or a copolymer thereof.

1-50 mass parts is preferable with respect to 100 mass parts of anionic polymers, and, as for the ratio of these crosslinking agents with respect to anionic polymer, 10-20 mass parts is more preferable. When the ratio of the crosslinking agent is 1 part by mass or more with respect to 100 parts by mass of the anionic polymer, a crosslinked structure is easily formed. When the ratio of the crosslinking agent is 50 parts by mass or less with respect to 100 parts by mass of the anionic polymer, the pot life of the coating liquid is improved.
The method of crosslinking the anionic polymer is not limited to the crosslinking agent, and may be a method of forming ionic crosslinking using a titanium or zirconium compound.

Examples of the cationic polymer include a polymer having an amine, polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is grafted to an acrylic main skeleton, Examples thereof include cationic polymers such as polyallylamine, derivatives thereof, and aminophenol.
The cationic polymer is preferably used in combination with a crosslinking agent having a functional group capable of reacting with an amine / imine such as a carboxy group or a glycidyl group. As the crosslinking agent used in combination with the cationic polymer, a polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine can also be used. For example, a polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, or the like. And a copolymer having a carboxy group such as carboxymethyl cellulose or an ionic salt thereof. Examples of polyallylamine include homopolymers or copolymers of allylamine, allylamine amide sulfate, diallylamine, dimethylallylamine, and the like. These amines may be free amines or may be stabilized with acetic acid or hydrochloric acid. Moreover, you may use a maleic acid, sulfur dioxide, etc. as a copolymer component. Furthermore, the type which gave the thermal crosslinking property by partially methoxylating a primary amine can also be used, and aminophenol can also be used. In particular, allylamine or a derivative thereof is preferable.
In the present invention, the cationic polymer is also described as one component constituting the corrosion prevention treatment layer 14. The reason for this is that, as a result of intensive studies using various compounds to provide the electrolyte resistance and hydrofluoric acid resistance required for the exterior materials for lithium ion batteries, the cationic polymer itself also has electrolyte resistance and anti-fluorine resistance. This is because the compound was found to be capable of imparting acidity. This factor is presumed to be because the aluminum foil is suppressed from being damaged by supplementing fluorine ions with a cationic group (anion catcher).

  Cationic polymers are more preferred materials in terms of improved adhesion. Moreover, since the cationic polymer is water-soluble, like the anionic polymer, it is more preferable to form a crosslinked structure and impart water resistance. As the crosslinking agent for forming a crosslinked structure in the cationic polymer, the crosslinking agent described in the section of the anionic polymer can be used, and the preferable range of the ratio to be used is also the same. When a rare earth oxide sol is used as the corrosion prevention treatment layer 14, a cationic polymer may be used instead of the anionic polymer as the protective layer.

  The corrosion prevention treatment layer 14 is not limited to the layer described above. For example, it may be formed by using a treating agent in which phosphoric acid and a chromium compound are blended in a resin binder (such as aminophenol) as in the case of a coating chromate that is a known technique. If this processing agent is used, it can be set as the layer which has both a corrosion prevention function and adhesiveness. In addition, although it is necessary to consider the stability of the coating liquid, both a corrosion prevention function and adhesion are achieved by using a coating agent in which a rare earth oxide sol and a polycationic polymer or polyanionic polymer are preliminarily made into one liquid. It can be a combined layer.

A lithium ion battery using a packaging material made of a multilayer film is sealed by heat sealing the sealant layers of the packaging material together. For this reason, there is a concern that moisture may enter from the end face of the seal portion where the sealant layer is combined and the lithium salt will be hydrolyzed. Therefore, it is necessary to increase the interlayer adhesion strength between the aluminum foil layer and the sealant layer and to improve the content resistance (electrolytic solution resistance and hydrofluoric acid resistance). As a method for improving resistance to electrolytic solution and hydrofluoric acid, trivalent chromate treatment is generally used. In order to form an inclined structure with the aluminum foil, the anti-corrosion treatment layer represented by the chemical treatment represented by chromate treatment is an aluminum foil that uses a chemical conversion treatment agent that contains hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, or a salt thereof. Then, a chemical conversion treatment layer is formed on the aluminum foil by the action of chromium or a non-chromium compound. However, since the chemical conversion treatment uses an acid as the chemical conversion treatment agent, it involves deterioration of the working environment and corrosion of the coating apparatus. On the other hand, unlike the chemical conversion treatment typified by the chromate treatment, the coating type corrosion prevention treatment layer 14 described above does not require an inclined structure to be formed on the aluminum foil layer 13. Therefore, the properties of the coating agent are not subject to restrictions such as acidity, alkalinity, and neutrality, and a favorable working environment can be realized.
In addition, especially in Europe, there is a movement to eliminate hexavalent chromate treated products because of not only causing chromium allergy and ulcers but also suspected carcinogenicity (RoHS regulations, REACH regulations). This movement may also affect trivalent chromate. Thus, the chromate treatment using a chromium compound is preferably a coating type corrosion prevention treatment layer 14 that is different from the chemical conversion treatment type from the viewpoint that an alternative is required for environmental hygiene.

  As the corrosion prevention treatment layer 14, a layer comprising a rare earth element-based oxide sol containing a mixture containing an anionic polymer and a crosslinking agent for crosslinking the anionic polymer, or a cationic polymer and the cationic polymer. A multilayer structure in which at least one of layers containing a mixture containing a crosslinking agent to be crosslinked is laminated is particularly preferable.

  You may mix | blend various additives with the corrosion prevention process layer 14 as needed. For example, when an etching function for aluminum foil is required, various acids or bases may be added. Various inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid and the like can be used if the components constituting the corrosion prevention treatment layer 14 are acidic, and chemical soda and the like can be used if basic. it can. Moreover, you may use the functional additive according to required quality, such as surfactant (leveling agent etc.), a ultraviolet absorber, antioxidant.

Mass per unit area of the corrosion prevention treatment layer 14 is a multilayer structure, be either single-layer structure, preferably ^{0.005~0.200g / m 2, 0.010~0.100g / m} 2 Gayori preferable. If the mass per unit area is 0.005 g / m ² or more, the aluminum foil layer 13 is easily imparted with a corrosion prevention function. Moreover, even if the mass per unit area exceeds 0.200 g / m ² , the corrosion prevention function does not change much. On the other hand, when the rare earth oxide sol is used, if the coating film is thick, curing due to heat at the time of drying becomes insufficient, and there is a possibility that the cohesive force is lowered. In addition, about the thickness of the corrosion prevention process layer 14, it can convert from the specific gravity.

(Second adhesive layer)
The second adhesive layer 15 is a layer that bonds the corrosion prevention treatment layer 14 and the sealant layer 16 together. The second adhesive layer 15 is a layer containing an adhesive or an adhesive resin. When the second adhesive layer 15 is formed by an adhesive described later, the exterior material 1 (dry laminate type) can be formed by dry lamination. When the second adhesive layer 15 is formed of an adhesive resin described later, the exterior material 1 (thermal laminate type) can be formed by thermal lamination.

The adhesive constituting the second adhesive layer 15 includes a main component such as polyester polyol, polyether polyol, acrylic polyol, and polyolefin polyol, an aromatic or aliphatic bifunctional or higher isocyanate compound as a curing agent, or its A two-component curable polyurethane adhesive in which a polyisocyanate compound composed of an adduct body, a burette body or a trimer is allowed to act is preferable.
The thickness of the second adhesive layer 15 formed by the adhesive is preferably 1 to 10 μm, more preferably 3 to 7 μm from the viewpoints of adhesive strength, followability, workability, and the like.

When the second adhesive layer 15 is formed of an adhesive resin, the adhesive resin is, for example, a polyolefin resin that is an unsaturated carboxylic acid derivative component derived from an unsaturated carboxylic acid or an acid anhydride or an ester thereof. And a modified polyolefin resin obtained by graft modification in the presence of an organic peroxide.
Examples of the polyolefin resin include low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, homo, block, random polypropylene, and propylene-α olefin copolymer. A polyolefin resin may be used individually by 1 type, and may use 2 or more types together.
Examples of the compound used for graft-modifying the polyolefin resin include unsaturated carboxylic acids or acid anhydrides or esters thereof (hereinafter collectively referred to as “unsaturated carboxylic acid etc.”). Specific examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid and the like. Saturated carboxylic acid; of unsaturated carboxylic acid such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride Anhydride: methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, dimethyl tetrahydrophthalic anhydride, bicyclo [2,2 , 1] Unsaturated carboxylic acids such as dimethyl-2-hept-2-ene-5,6-dicarboxylate And the like esters of. These compounds may be used individually by 1 type, and may use 2 or more types together.
As the adhesive resin, a maleic anhydride-modified polyolefin resin obtained by graft-modifying a polyolefin resin with maleic anhydride is particularly preferable.

Moreover, when forming the 2nd contact bonding layer 15 by adhesive resin, you may form by extrusion lamination and you may form by the dispersion type which disperse | distributed the said material to the organic solvent. Further, in the case of this dispersion type, various additives such as a crosslinking agent and a silane coupling agent may be blended.
1-40 micrometers is preferable and, as for the thickness of the 2nd contact bonding layer 15 formed with adhesive resin, 5-20 micrometers is more preferable.

(Sealant layer)
The sealant layer 16 is a layer that is bonded to the aluminum foil layer 13 on which the corrosion prevention treatment layer 14 is formed via the second adhesive layer 15, and provides sealing performance by heat sealing in the exterior material 1.
Examples of the component constituting the sealant layer 16 include a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying maleic anhydride or the like on a polyolefin resin. Examples of the polyolefin resin are the same as those mentioned in the section of the second adhesive layer 15.
The sealant layer 16 may be a single layer film or a multilayer film in which a plurality of layers are laminated. As the sealant layer 16 having a multilayer structure, for example, a multilayer film in which a resin such as an ethylene-cycloolefin copolymer or polymethylpentene is interposed in order to impart moisture resistance can be mentioned.

The sealant layer 16 may contain various additives such as a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.
10-100 micrometers is preferable and, as for the thickness of the sealant layer 16, 20-50 micrometers is more preferable.

The exterior material of the present invention described above has both excellent moldability and good bar code printability. In addition, by providing a corrosion prevention treatment layer using a rare earth element-based oxide sol without performing chromate treatment, environmental characteristics can be improved.
The exterior material of the present invention is not limited to the exterior material 1 described above. For example, for the purpose of increasing the adhesion strength between the first adhesive layer and the aluminum foil layer, a corrosion prevention treatment layer may be provided also on the base material layer side of the aluminum foil layer.

(Production method)
Hereinafter, the manufacturing method of the exterior material 1 is demonstrated as an example of the manufacturing method of the exterior material of this invention. However, the manufacturing method of the exterior material 1 is not limited to the following method.
The manufacturing method of the packaging material 1 includes the following steps (I) to (IV).
(I) A step of forming a corrosion prevention treatment layer 14 on the aluminum foil layer 13.
(II) The process of bonding the base material layer 11 through the 1st contact bonding layer 12 to the opposite side to the side in which the corrosion prevention process layer 14 in the aluminum foil layer 13 was formed.
(III) A step of bonding the sealant layer 16 to the corrosion prevention treatment layer 14 side of the aluminum foil layer 13 via the second adhesive layer 15.
(IV) A step of applying a slip agent to the outer surface of the base material layer 11 and the outer surface of the sealant layer 16.

Step (I):
The corrosion prevention treatment layer 14 is formed on one surface of the aluminum foil layer 13 by applying a coating agent having a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, a chemical conversion treatment, or a corrosion prevention performance.
Examples of the degreasing treatment include annealing, spraying, and dipping.
Examples of the hydrothermal transformation treatment and anodizing treatment include an immersion method.
As a chemical conversion treatment method, an immersion method, a spray method, a coating method, or the like can be selected according to the type of chemical conversion treatment.

Various coating methods such as a gravure coater, a gravure reverse coater, a roll coater, a reverse roll coater, a die coater, a bar coater, a kiss coater, and a comma coater can be adopted as a coating method of a coating agent having corrosion prevention performance.
The aluminum foil layer 13 may be an untreated aluminum foil or a degreased aluminum foil. As a method of degreasing, in addition to degreasing by annealing, the spray method or the dipping method described above can be used.

Process (II):
On the opposite side of the aluminum foil layer 13 to the side on which the corrosion prevention treatment layer 14 is formed, the base material layer 11 is formed by a technique such as dry lamination, non-solvent lamination, wet lamination using an adhesive that forms the first adhesive layer 12. Paste together.
In step (II), an aging treatment may be performed in the range of room temperature to 80 ° C. in order to promote adhesion.

Step (III):
When the second adhesive layer is formed of an adhesive, the base material layer 11, the first adhesive layer 12, the aluminum foil layer 13 and the corrosion prevention treatment layer 14 are laminated on the corrosion prevention treatment layer 14 side in this order. Bond the sealant layer by dry lamination, non-solvent lamination, wet lamination, etc. Also in this case, similarly to the step (II), an aging treatment (curing) may be performed in the range of room temperature to 80 ° C. in order to promote adhesion.

Further, when the second adhesive layer 15 is formed of an adhesive resin, a dry process or a wet process can be used.
In the case of a dry process, a sealant layer 16 obtained by an inflation method or a casting method is bonded to the corrosion prevention treatment layer 14 side of the laminate by an adhesive resin by sand lamination using an extrusion laminator. Thereafter, heat treatment (such as aging treatment or thermal lamination) may be performed for the purpose of improving the adhesion between the corrosion prevention treatment layer 14 and the second adhesive layer 15 formed of an adhesive resin.
In the case of a wet process, a dispersion of an adhesive resin is applied on the corrosion prevention treatment layer 14 of the laminate and baked, and then the sealant layer 16 obtained by an inflation method or a cast method is subjected to thermal lamination or the like. Laminate by heat treatment.

Process (IV):
A slip agent is applied to the outer surface (outermost surface) of the base material layer 11 and the outer surface (outermost surface) of the sealant layer 16 to reduce the static friction coefficient, the static friction coefficient (μs-A), and the static friction coefficient (μs). -B), adjusting their ratio (μs-A / μs-B).
Examples of the method for applying the slip agent include a method in which the slip agent is dissolved and dispersed in a solvent using a dry laminating method.

The exterior material 1 is obtained by the steps (I) to (IV) described above.
In addition, the manufacturing method of the exterior material 1 is not limited to the method of implementing the said process (I)-(IV) sequentially. For example, step (I) may be performed after performing step (II). Moreover, you may provide a corrosion prevention process layer on both surfaces of an aluminum foil layer. Moreover, you may perform process (II) after performing process (III). Further, when a slip agent is blended in the base material layer 11 or the sealant layer 16, step (IV) may not be performed.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Raw materials]
The raw materials used in this example are shown below.
(Base material layer 11)
Base material A-1: Biaxially stretched polyamide film (thickness 25 μm).

[First adhesive layer 12]
Adhesive B-1: A polyurethane-based adhesive (manufactured by Toyo Ink Co., Ltd.) in which an adduct-based curing agent of tolylene diisocyanate is blended with a polyester polyol-based main agent.

(Aluminum foil layer 13, corrosion prevention treatment layer 14)
Aluminum foil C-1: As a corrosion prevention treatment layer, a layer made of cerium oxide sol, a layer made of polyacrylic acid resin that is an anionic polymer, and a layer made of polyallylamine resin that is a cationic polymer on one side Soft aluminum foil 8079 laminated in sequence (aluminum foil thickness 40 μm).
Aluminum foil C-2: Soft aluminum foil 8079 material (aluminum foil thickness 40 μm) provided with a corrosion prevention treatment layer composed of trivalent chromate and phenolic resin on both sides as a coating type chemical conversion treatment layer.
The corrosion prevention treatment layer was provided by gravure reverse coating, and was baked at 150 to 200 ° C. in a drying unit. The mass per unit area of the corrosion prevention treatment layer was set to 0.010 to 0.100 g / m ² .

(Second adhesive layer 15)
Adhesive D-1: Polyurethane adhesive (manufactured by Mitsui Chemicals) in which an adduct-based curing agent of tolylene diisocyanate is blended with a polyester polyol-based main agent.
Adhesive resin D-2: Maleic anhydride modified polypropylene adhesive resin (Admer made by Mitsui Chemicals).

(Sealant layer 16)
Film E-1: An unstretched polypropylene film (thickness of 30 μm) having a corona treatment applied to the innermost surface.

(Slip agent)
Slip agent F-1: erucic acid amide

[Method of manufacturing exterior material]
The said aluminum foil (C-1, C-2) and base material A-1 were bonded together by the dry laminating method using adhesive agent B-1. The thickness of the first adhesive layer 12 was 4 μm. Next, the film E-1 is bonded to the opposite side of the base material layer of the laminate by the dry lamination using the adhesive D-1 or the extrusion lamination using the adhesive resin D-2, and the sealant layer. And an exterior material was obtained. The thickness of the second adhesive layer 15 was 4 μm when the adhesive D-1 was used, and 20 μm when the adhesive resin D-2 was used. The exterior material manufactured by extrusion lamination was further subjected to thermocompression bonding (heat treatment) at 210 ° C. and 5 m / min. Thereafter, a coating agent in which erucamide was dissolved in isopropyl alcohol at a concentration such that the static friction coefficient of the outer surface of the base material layer and the static friction coefficient of the outer surface of the sealant layer are as shown in Table 1, the base material layer and the sealant It was applied to each surface of the layer.

[Measurement of static friction coefficient]
The outer surface of the base material layer in the exterior material obtained in each example, that is, the outermost surface at the time of manufacturing the battery, and the outer surface of the sealant layer, that is, the outermost surface of the inner surface at the time of manufacturing the battery comply with JIS-P8147. And measured.

[Evaluation of formability]
A test piece cut out in a size of 50 × 70 mm from the obtained exterior material was drawn at intervals of 0.25 mm using a cold forming apparatus capable of adjusting the drawing depth from 3.00 mm to 10.00 mm. Deep drawing was performed while changing the depth, and formability was evaluated. Evaluation was performed according to the following criteria.
(Double-circle): Even if the drawing depth exceeded 4.50 mm, it was possible to perform deep drawing without causing pinholes or cracks.
◯: Deep drawing was possible without causing pinholes and cracks within a drawing depth of 4.25 to 4.50 mm.
(Triangle | delta): It was able to be deep-draw-molding without producing a pinhole or a crack in the range of drawing depth of 4 to 4.25 mm.
X: Pinholes and cracks occurred at a drawing depth of less than 4 mm.

[Amount of surface slip agent]
The amount of slip agent applied to the surface of the base material layer and the sealant layer was calculated by measuring the amount of slip agent extracted from each surface with chloroform by GC-MS and using a calibration curve prepared in advance. .

[Bar code printing evaluation]
100 barcodes were printed on the base material layer side with an ink jet printer, and it was evaluated whether or not the barcode could be read with a barcode reader. Evaluation was performed according to the following criteria.
A: There were 1 or less barcodes that were poorly read.
Δ: There were 2 to 9 barcodes with poor reading.
X: There were 10 or more barcodes that were poorly read.

[Comprehensive evaluation]
Comprehensive evaluation was performed according to the following criteria, and Δ or more was regarded as acceptable.
(Double-circle): Formability evaluation was "(double-circle)" and barcode printing evaluation was "(circle)".
◯: Formability evaluation was “◯” and bar code printing evaluation was “◯”.
Δ: Formability evaluation and bar code printing evaluation were “Δ” or more, and either one was “Δ”.
X: At least one of the moldability evaluation and the bar code printing evaluation was “x”.

[Examples 1-6 and Comparative Examples 1-3]
By the said manufacturing method, the exterior material of the structure shown in Table 1 was manufactured, and the moldability and barcode printability were evaluated.

As shown in Table 2, the exteriors of Examples 1 to 6 in which the static friction coefficient (μs-A) of the surface of the base material layer 11 and the static friction coefficient (μs-B) of the surface of the sealant layer 16 are within suitable ranges, respectively. The material had an excellent moldability with a large drawable depth and good bar code printability. Moreover, the exterior materials of Examples 3 to 6 in which the ratio of the static friction coefficient (μs-A / μs-B) is within the range of 0.33 to 2.4 were further excellent in moldability. Further, in Examples 1 to 5 in which the amount of the slip agent was less than 50 mg / m ² and the static friction coefficient (μs-A) exceeded 0.10, the bar code printability was particularly good.

  On the other hand, the exterior materials of Comparative Examples 1 to 3, in which one of the static friction coefficient (μs-A) of the surface of the base material layer 11 and the static friction coefficient (μs-B) of the surface of the sealant layer 16 does not satisfy the condition, Molding defects occurred at less than 0.4 mm, and the moldability was inferior to the examples.

DESCRIPTION OF SYMBOLS 1 Exterior material for lithium ion batteries 11 Base material layer 12 1st contact bonding layer 13 Aluminum foil layer 14 Corrosion prevention processing layer 15 2nd contact bonding layer 16 Sealant layer

Claims (3)

A lithium ion battery exterior material in which a first adhesive layer, an aluminum foil layer provided with a corrosion prevention treatment layer on at least one surface, a second adhesive layer, and a sealant layer are sequentially laminated on one surface of the base material layer,
The static friction coefficient (μs-A) of the outer surface of the base material layer is 0.1 to 0.25, and the static friction coefficient (μs-B) of the outer surface of the sealant layer is 0.1 to 0.5. der is, and the ratio of the static friction coefficient of the outer surface of the base layer coefficient of static friction of the outer surface of the (μs-a) and the sealant layer (μs-B) (μs- a / μs-B) is A packaging material for a lithium ion battery, characterized by being 0.8 to 1.2 . The slip agent was applied to the outer surface of the base material layer at a rate of 1 to 20 mg / m ² , and the slip agent was applied to the outer surface of the sealant layer at a rate of 1 to 20 mg / m ^2. The exterior material for lithium ion batteries according to 1 . The corrosion prevention treatment layer is a layer comprising a rare earth element-based oxide sol containing a mixture containing an anionic polymer and a crosslinking agent for crosslinking the anionic polymer, or a cationic polymer and the cationic polymer are crosslinked. The exterior material for a lithium ion battery according to claim 1 or 2 , which has a multilayer structure in which at least one of layers containing a mixture containing a crosslinking agent is laminated.

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