JP2010102935A - Cladding material for lithium battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium battery exterior sheet in which electrolytic solution resistance property is superior and whitening can be suppressed. <P>SOLUTION: This lithium battery exterior sheet 10 comprises a laminated body in which at least an aluminum foil layer (AL) 13, an adhesive resin layer (AR) 15, and a sealant layer (SL) 16 are sequentially laminated. The adhesive resin layer (AR) 15 contains 50 to 99 wt.% of resin composition (A) containing modified polyolefin resin (A-1) and 1 to 50 wt.% of thermoplastic elastomer (B). The thermoplastic elastomer (B) forms a micro-phase separation structure against the modified polyolefin resin (A-1) of which a dispersion-phase size ranges from 1 to 200 nm. The melting point (Tm(AR)) of the adhesive resin layer (AR) 15 and the melting point (Tm(SL)) of the sealant layer (SL) 16 satisfy an equation 1 (Tm(SL)-Tm(AR≥10) when the adhesive resin layer (AR) 15 and/or the sealant layer (SL) 16 have a plurality of melting points, the highest temperature is used as the melting point). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In recent years, lithium-ion secondary batteries (hereinafter referred to as “lithium-ion secondary batteries”) that are high energy, ultra-thin and miniaturized can be used as consumer-use secondary batteries used in personal digital assistants such as personal computers and mobile phones, and video cameras. Battery ") is being actively developed. Unlike the metal cans used as conventional battery outer packaging materials, the outer packaging material used for this lithium battery is a multilayer film (for example, a heat-resistant substrate) because it is lightweight and can freely select the shape of the battery. Layer / aluminum foil layer / heat-fusible film layer) having a bag shape has been used.

In the lithium battery, a lithium salt as an electrolyte was dissolved in an aprotic solvent having penetrating power such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate together with a positive electrode material and a negative electrode material as battery contents. An electrolyte layer made of an electrolyte solution or a polymer gel impregnated with the electrolyte solution is included. When the solvent having such penetrating power passes through the heat-fusible film layer serving as a sealant, the laminate strength between the aluminum foil layer and the heat-fusible film layer is lowered, and the electrolyte solution eventually leaks. was there.
In addition, lithium salts such as LiPF ₆ and LiBF ₄ are used as the lithium salt that is an electrolyte of the battery. These salts generate hydrofluoric acid by hydrolysis reaction with moisture, corrosion of the metal surface, and multilayer film. In some cases, the laminate strength between each layer may be reduced. By using aluminum foil, moisture intrusion from the surface of the outer packaging material is almost blocked, but the outer packaging material for lithium batteries has a structure in which multilayer films are bonded together by heat sealing. There is concern about the hydrolysis of the lithium salt due to moisture entering from the end face of the seal part of the adhesive film layer. For this reason, it has been essential to increase the interlayer adhesion strength between the aluminum foil and the heat-fusible film layer and to have content resistance (electrolytic solution resistance and hydrofluoric acid resistance).
Furthermore, lithium batteries are often used for portable mobile phones, and the usage environment may be as high as 60 to 70 ° C., for example, in a midsummer car. It was necessary to impart resistance to the electrolytic solution to the battery exterior material.

  In addition, in recent years, the automobile industry has been developing vehicles using only secondary batteries or a combination of gasoline and secondary batteries, such as electric vehicles (EV) and hybrid electric vehicles (HEV); solar cells and wind power generation For large-scale applications such as electric double layer capacitors (EDLC) for accumulating electric power generated in the market and lithium-ion capacitors (LIC) that have the characteristics of both secondary batteries and capacitors. In the secondary battery / capacitor market, not only battery performance but also higher safety and long-term stability (10 to 30 years) are required.

In general, lithium batteries used in consumer applications have functions required for delamination between the aluminum foil layer and the heat-fusible film layer due to the influence of hydrofluoric acid generated by hydrolysis of the electrolyte or electrolyte lithium salt. Suppression.
Thus, for example, Patent Documents 1 to 3 disclose a packaging material for a lithium battery in which delamination hardly occurs with respect to an electrolytic solution or hydrofluoric acid.
In addition, if the exterior material for a lithium battery is produced by a dry lamination method, the urethane adhesive used in the production may swell due to the electrolytic solution and cause delamination. It is produced by such a method.
Thus, for example, Patent Document 4 discloses a technique for improving a urethane-based adhesive used in a dry laminating method, and thereby a urethane-based adhesive having an electrolyte resistance can be obtained. An exterior material with reduced lamination can be produced.

  On the other hand, in the case of a lithium battery used in a large-scale application, as described above, demands for safety and long-term stability are increasing, and in particular, a required function of a lithium battery exterior material for packaging a lithium battery is increasing. One of the required functions is water resistance and hydrofluoric acid resistance. As described above, hydrofluoric acid is conventionally generated by hydrolysis of lithium salt, which is an electrolyte. Evaluation using water as a method has hardly been performed. However, in the case of a large-sized lithium battery, the environment in which it is used is more severe than that for consumer use. For this reason, it has become necessary to study an evaluation assuming that the aluminum foil is corroded and causes delamination due to an increase in the amount of hydrofluoric acid generated due to excessive moisture absorption. From such a viewpoint, the case of evaluating water resistance and hydrofluoric acid resistance as an evaluation method for a lithium battery exterior material is increasing. When evaluating an electrolyte for a lithium battery exterior material, a strip-shaped exterior material sample (for example, a heat-resistant substrate layer / aluminum foil layer / a heat-sealable film layer) is usually immersed in the electrolyte at 85 ° C. Apply processing to check for delamination. Furthermore, a method has also been proposed in which both the handling of the evaluation and the evaluation of water resistance are performed, and after immersing in an electrolytic solution, washing with water and then immersing in water. Furthermore, an accelerated test is conducted in which an immersion treatment is performed at 85 ° C. in an electrolytic solution in which water corresponding to several thousand ppm is dropped in advance, and evaluation is performed in a state where excess hydrofluoric acid is generated.

As the most effective method for imparting such resistance (electrolytic solution resistance, water resistance, hydrofluoric acid resistance), a method of performing chemical conversion treatment on aluminum foil is known, and chromate treatment is an example of chemical conversion treatment. .
For example, Patent Document 5 discloses many chromate treatments such as a coating type chromate treatment and a chromate treatment by an immersion method.
Chemical conversion treatments typified by such chromate treatments are being studied regardless of consumer use or large-scale use. In recent years, in consideration of environmental effects of chromium compounds, methods for performing corrosion prevention treatment of aluminum foil layers without using chromium compounds have been studied.
For example, Patent Document 6 discloses a packaging material for lithium electronic that is provided with electrolytic resistance, hydrofluoric acid resistance, and water resistance without using a chromium compound.

By the way, the production method of the exterior material for lithium batteries is different between consumer use and large-scale use. Normally, in the case of consumer use, the exterior material for lithium battery is produced by the dry laminating method described in Patent Document 4, for example. To do. On the other hand, in the case of large-scale applications, the dry laminating method is not suitable because the adhesive swells or dissolves when manufactured by the dry laminating method. Therefore, from the viewpoint of reliability and long-term stability, for example, it is often manufactured by a thermal laminating method as described in Patent Document 5, for example.
Japanese Patent Laid-Open No. 2001-243928 JP 2004-42477 A JP 2004-142302 A JP 2002-187233 A JP 2002-144479 A JP 2007-280923 A

  However, the outer packaging material for lithium batteries manufactured by the thermal laminating method as described in Patent Document 5 satisfies the electrolytic solution resistance required in large-scale applications, while cold formability is regarded as a problem. Sometimes. In general, an outer packaging material for a lithium battery made of a multi-layer film is cold-molded to attach the battery body to the molded drawing part, and finally heat-sealed and sealed. The thermal laminating method is excellent in that the adhesion between the aluminum foil layer and the heat-fusible film layer is improved by thermocompression bonding, but crystallization is likely to proceed due to excessive heat applied to the heat-fusible film layer. It was. Further, fine cracks are likely to occur in the heat-fusible film layer due to the strain generated during cold forming, and the film whitening phenomenon is likely to occur particularly in the narrowed portions such as the molded side surfaces and corners. When cracks are generated, the fine cracks are gathered together, causing the heat-fusible film itself to break, and further causing the aluminum foil layer and the heat-resistant base material layer to break.

Such a breakage of the heat-fusible film or the like becomes a serious problem as an outer packaging material for a lithium battery that is required to encapsulate and seal the electrolytic solution. Therefore, since the whitening phenomenon in cold forming is also considered as a sign of causing the fracture of the lithium battery exterior material itself, it is required to suppress the whitening phenomenon as well as the fracture.
Such a problem of occurrence of the whitening phenomenon is unlikely to occur in the case of a dry laminating method that does not involve an excessive amount of heat during production, but as described above, it is not suitable for large-scale applications from the viewpoint of reliability and long-term stability. is there.
On the other hand, in the case of the heat laminating method, an outer packaging material for a lithium battery excellent in electrolytic solution resistance can be manufactured.

  This invention considers the said situation, and it aims at provision of the exterior material for lithium batteries which can suppress a whitening phenomenon while being excellent in electrolyte solution resistance.

The lithium battery exterior material of the present invention is a lithium battery exterior material comprising a laminate in which at least an aluminum foil layer (AL), an adhesive resin layer (AR), and a sealant layer (SL) are sequentially laminated. The resin layer (AR) contains 50 to 99% by mass of the resin composition (A) containing the modified polyolefin resin (A-1) and 1 to 50% by mass of the thermoplastic elastomer (B) (however, the resin composition) The total of the product (A) and the thermoplastic elastomer (B) is 100% by mass), and the thermoplastic elastomer (B) has a dispersed phase size of 1 to 1 with respect to the modified polyolefin resin (A-1). A micro phase separation structure is formed in the range of 200 nm, and the melting point (Tm (AR)) of the adhesive resin layer (AR) and the melting point (Tm (SL)) of the sealant layer (SL) are expressed by the following formulae. (1 The satisfied (when the adhesive resin layer (AR) and / or sealant layer (SL) has a plurality of melting point, and the melting point of the highest temperature.) It is characterized.
Tm (SL) −Tm (AR) ≧ 10 (1)

Further, the modified polyolefin resin (A-1) includes an unsaturated carboxylic acid derivative component derived from an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, or an ester of an unsaturated carboxylic acid. A graft-modified resin is preferred.
Furthermore, the resin composition (A) is a thermoplastic elastomer (A-2) that forms a macrophase separation structure in a range where the dispersed phase size exceeds 200 nm and is 50 μm or less with respect to the modified polyolefin resin (A-1). ) Is preferably contained.
Moreover, it is preferable that the thermoplastic elastomer (B) is a styrene elastomer or a hydrogenated styrene elastomer obtained by polymerizing a monomer component containing 1 to 20% by mass of a styrene monomer.

Furthermore, the corrosion prevention treatment layer (CL) containing a polymer having a functional group that reacts with the unsaturated carboxylic acid derivative component constituting the modified polyolefin resin (A-1) includes the aluminum foil layer (AL) and the It is preferable to be laminated between the adhesive resin layers (AR).
The polymer is preferably a cationic polymer.
Furthermore, the cationic polymer is polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin obtained by grafting a primary amine on an acrylic main skeleton, polyallylamine or a derivative thereof, It is preferably at least one selected from the group consisting of aminophenols.

According to the outer packaging material for a lithium battery of the present invention, the electrolyte solution resistance is excellent and the whitening phenomenon can be suppressed.
In addition, according to the present invention, the cold formability can be improved, and therefore, it is particularly suitable for producing a large-sized lithium battery exterior material employing a heat laminating method. Furthermore, the present invention is difficult to apply environmentally.

Hereinafter, the present invention will be described in detail.
The lithium battery exterior material of the present invention (hereinafter abbreviated as “exterior material”) is a laminate in which at least an aluminum foil layer (AL), an adhesive resin layer (AR), and a sealant layer (SL) are sequentially laminated. Become.
FIG. 1 shows an example of the exterior material of the present invention. In this example, the exterior material 10 includes a pressure-sensitive adhesive layer (AD) 12, an aluminum foil layer (AL) 13, a corrosion prevention treatment layer (CL) 14, an adhesive resin layer on one surface of a base material layer (SB) 11. (AR) 15 and sealant layer (SL) 16 are sequentially laminated.

<Adhesive resin layer (AR)>
The adhesive resin layer (AR) contains a resin composition (A) containing a modified polyolefin resin (A-1) and a thermoplastic elastomer (B).
In the modified polyolefin resin (A-1), an unsaturated carboxylic acid derivative component derived from any of an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, or an ester of an unsaturated carboxylic acid is graft-modified to the polyolefin resin. It is preferable to use a resin.

  Examples of the polyolefin resin include polyolefin resins such as low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, homo, block, random polypropylene, and propylene-α olefin copolymer.

Examples of the compound used when graft-modifying these polyolefin resins include unsaturated carboxylic acid derivative components derived from any of unsaturated carboxylic acids, unsaturated carboxylic acid anhydrides, and unsaturated carboxylic acid esters. .
Specifically, as the unsaturated carboxylic acid, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo [2,2,1] hept-2-ene-5, Examples include 6-dicarboxylic acid.
Examples of unsaturated carboxylic acid anhydrides include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic anhydride And acid anhydrides of unsaturated carboxylic acids.
Examples of unsaturated carboxylic acid esters include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, tetrahydrophthalic anhydride Examples include esters of unsaturated carboxylic acids such as dimethyl and dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylate.

The modified polyolefin resin (A-1) is graft polymerized (grafted modified) in the presence of a radical initiator in the presence of 0.2 to 100 parts by mass of the unsaturated carboxylic acid derivative component described above with respect to 100 parts by mass of the base polyolefin resin. Can be manufactured.
The reaction temperature is preferably 50 to 250 ° C, more preferably 60 to 200 ° C.
The reaction time is appropriately set according to the production method. For example, in the case of melt graft polymerization using a twin screw extruder, the residence time of the extruder is specifically 2 to 30 minutes, specifically 5 to 10 minutes. More preferred.
The graft modification can be carried out under normal pressure or pressurized conditions.

Examples of radical initiators used for graft modification include organic peroxides such as alkyl peroxides, aryl peroxides, acyl peroxides, ketone peroxides, peroxyketals, peroxycarbonates, peroxyesters, and hydroperoxides. It is done.
These organic peroxides can be appropriately selected and used depending on the reaction temperature and reaction time conditions described above. For example, in the case of melt graft polymerization using a twin-screw extruder, alkyl peroxides, peroxyketals, and peroxyesters are preferred, specifically, di-t-butyl peroxide, 2,5-dimethyl-2,5-di -T-Butylperoxy-hexyne-3, dicumyl peroxide and the like are preferable.

The modified polyolefin resin (A-1) is preferably a polyolefin resin modified with maleic anhydride, such as “Admer” manufactured by Mitsui Chemicals, “Modic” manufactured by Mitsubishi Chemical, and “Adtex” manufactured by Nippon Polyethylene. Is suitable.
Since such a modified polyolefin resin (A-1) is excellent in reactivity with various metals and polymers having various functional groups, the adhesiveness can be imparted to the adhesive resin layer (AR) using the reactivity. The resistance to electrolytic solution can be improved.

The resin composition (A) preferably contains a thermoplastic elastomer (A-2) in addition to the modified polyolefin resin (A-1) described above.
The thermoplastic elastomer (A-2) is a material that forms a macrophase separation structure in the range of the dispersed phase size exceeding 200 nm and 50 μm or less with respect to the modified polyolefin resin (A-1). And thermoplastic elastomers of the system. Hereinafter, the thermoplastic elastomer (A-2) is referred to as “macro thermoplastic elastomer (A-2)” in the present specification.

Residue generated when the modified polyolefin resin (A-1) and the like constituting the adhesive resin layer (AR) are laminated because the resin composition (A) contains the macro thermoplastic elastomer (A-2). Stress can be released and thermoelastic adhesion can be imparted to the adhesive resin layer (AR). Therefore, the adhesiveness of the adhesive resin layer (AR) is further improved, and an exterior material that is more excellent in electrolytic solution resistance can be obtained.
The macro thermoplastic elastomer (A-2) exists in a sea-island shape on the modified polyolefin resin (A-1), but gives an improvement in viscoelastic adhesion when the dispersed phase size is 200 nm or less. It becomes difficult. On the other hand, when the dispersed phase size exceeds 50 μm, the modified polyolefin resin (A-1) and the macro thermoplastic elastomer (A-2) are essentially incompatible, so the laminate suitability (workability) is significantly reduced. At the same time, the physical strength of the adhesive resin layer (AR) tends to decrease. The dispersed phase size is preferably 500 nm to 10 μm.

Such macro thermoplastic elastomer (A-2) is selected from, for example, ethylene and / or propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene. Examples thereof include polyolefin-based thermoplastic elastomers obtained by copolymerizing α-olefins.
As the macro thermoplastic elastomer (A-2), commercially available products can be used. For example, “Tuffmer” manufactured by Mitsui Chemicals, “Zeras” manufactured by Mitsubishi Chemical, and “Cataloy” manufactured by Montel. Is suitable.

  When the resin composition (A) contains the macro thermoplastic elastomer (A-2), the content thereof is preferably 1 to 40 parts by mass with respect to 100 parts by mass of the modified polyolefin resin (A-1). 5-30 mass parts is more preferable. When the content of the macro thermoplastic elastomer (A-2) is less than 1 part by mass, improvement in the adhesion of the adhesive resin layer (AR) cannot be expected. On the other hand, if the content of the macro thermoplastic elastomer (A-2) exceeds 40 parts by mass, the modified polyolefin resin (A-1) and the macro thermoplastic elastomer (A-2) are inherently low in compatibility. Therefore, the workability is remarkably deteriorated. Further, since the macro thermoplastic elastomer (A-2) is not a resin exhibiting adhesiveness, the adhesive resin layer (AR) adheres to other layers such as a sealant layer (SL) and a corrosion prevention treatment layer (CL). It becomes easy to fall.

As a result of intensive studies on the whitening phenomenon that occurs when the exterior material is cold-formed, the present inventors have arrived at the mechanism shown below. Here, in order to elucidate the mechanism of the whitening phenomenon, the macromolecular thermoplastic elastomer (A-2) 15a ₂ is blended with the modified polyolefin resin (A-1) 15a ₁ as shown in FIG. 2 (a). The adhesive resin layer (AR) 15 will be described as an example.
(I) The modified polyolefin resin (A-1) 15a _{1 in} the adhesive resin layer (AR) 15 is crystallized by heat treatment during thermal lamination.
(Ii) Since the modified polyolefin resin (A-1) 15a ₁ and the macro thermoplastic elastomer (A-2) 15a ₂ are incompatible, the crystallization behavior of (i) causes strain at the interface between them. Occurs.
(Iii) When stress is applied during molding, a crack occurs at the interface between the two, and void-craze 15a ₃ is formed (FIG. 2 (b)).
(Iv) Light is scattered by the void-craze 15a _{3 and} a whitening phenomenon occurs due to optical irregular reflection of light.

  From the above, in order to suppress the whitening phenomenon, the present inventors stated that “the crystallization of the modified polyolefin resin (A-1) does not proceed with the amount of heat at the time of thermal lamination (that is, it is difficult to crystallize)”. "Improvement of adhesion between the modified polyolefin resin (A-1) and the macro thermoplastic elastomer (A-2)" was found to be important. And as a result of earnest examination about the material which can achieve these, thermoplastic elastomer (B) which forms a micro phase separation structure in the range of 1-200 nm of dispersion phase sizes is optimal with respect to modified polyolefin resin (A-1). I found out. Hereinafter, the thermoplastic elastomer (B) is referred to as “micro thermoplastic elastomer (B)” in the present specification.

Here, the microphase separation structure means that when the micro thermoplastic elastomer (B) is present as the dispersed phase in the modified polyolefin resin (A-1), (1) the maximum diameter when the dispersed phase is approximated as an ellipse. (D ₁ ) is _{1 to} 200 nm, or ( ₂ ) the ratio (d ₁ / d ₂ ) between the maximum diameter (d ₁ ) of the dispersed phase domain and the maximum value (d ₂ ) of the diameter orthogonal to the maximum diameter. ) Is a rod-like dispersed phase of 20 or more and the maximum value (d ₂ ) is 1 to ₂₀₀ nm, or (3) the modified polyolefin resin (A-1) and the micro thermoplastic elastomer (B ) Has a layered lamellar structure in which it is impossible to determine which is a dispersed phase, and the thickness of at least one of the phase of the modified polyolefin resin (A-1) or the phase of the micro thermoplastic elastomer (B) 1 to 200 Is that of a m structure.
The macro phase separation structure described above is not a dispersion level at which a phase separation structure such as a micro phase separation structure cannot be confirmed, but a sea-island structure formed in a range where the dispersed phase size exceeds 200 nm and is 50 μm or less. That is.

In addition, as a method of confirming a micro phase separation structure, the method shown below is mentioned, for example.
First, a mixture of the modified polyolefin resin (A-1) and the micro thermoplastic elastomer (B) is formed into a press sheet, made into 0.5 mm square pieces, and dyed with ruthenic acid (RuO ₄ ). An ultrathin section having a film thickness of about 100 nm is prepared using an ultramicrotome (REICHERT ULTRACUT S, REICHERT FCS, etc.) equipped with a diamond knife.
Next, carbon is deposited on the ultrathin slice and observed with a transmission electron microscope. At least five observation spots are selected at random, and observed at magnifications of 10,000, 50,000, and 150,000 times. In this case, when the approximation as the ellipse of (1) described above is performed, the software of Image-Pro Plus is used in a field of view observed at 10,000 to 150,000 times with a transmission electron microscope. By selecting Axis-major, the dispersed phase is approximated to an ellipse having the same area and the same primary and secondary moments, and the major axis is the maximum diameter (d ₁ ).

  The micro thermoplastic elastomer (B) can inhibit the crystalline polymer folding structure (lamella structure) by finely dispersing in nanometer order with the modified polyolefin resin (A-1) having crystallinity. The crystallinity of the resin (A-1) can be reduced. Moreover, since generation | occurrence | production of the distortion in the interface of modified polyolefin resin (A-1) and macro-type thermoplastic elastomer (A-2) can be suppressed by suppressing crystallization of modified polyolefin resin (A-1), The adhesion between the modified polyolefin resin (A-1) and the macro thermoplastic elastomer (A-2) can be improved.

Examples of such micro thermoplastic elastomer (B) include “Notio” manufactured by Mitsui Chemicals, styrene elastomer, hydrogenated styrene elastomer, and the like. Of these, styrene elastomers and hydrogenated styrene elastomers are preferred. In particular, hydrogenated styrene-based elastomers are particularly preferable in terms of improving not only moldability characteristics such as suppression of the whitening phenomenon but also electrolytic solution resistance.
Examples of the styrene elastomer and hydrogenated styrene elastomer include block copolymers such as styrene and AB type and ABA type having a structural unit selected from ethylene, propylene, butylene and the like. -Ethylene / butylene-styrene copolymer, styrene-ethylene / propylene-styrene copolymer, and the like.

As such a styrene-type elastomer and a hydrogenated styrene-type elastomer, what polymerized the monomer component which contains 1-20 mass% of styrene monomers is preferable, More preferably, it is 5-15 mass%. Even if the content of the styrene monomer is less than 1% by mass, there is no problem in terms of suppression of the whitening phenomenon. However, although the styrene monomer is a component inferior in solvent resistance, the present inventors have formulated a monomer component containing a styrene monomer into the adhesive resin layer (AR) as an exterior material. It has been found that the resistance to electrolytic solution tends to be further improved. Giving electrolyte resistance means that it is necessary to keep the electrolyte solution as close as possible to the interface between the aluminum foil layer (AL) and the adhesive resin layer (AR), but it is easy to incorporate the solvent. By blending the styrene monomer, it is considered that the electrolytic solution is easily trapped by the styrene monomer, and diffusion of the electrolytic solution that permeates through the adhesive resin layer (AR) is suppressed. From such a viewpoint, a styrene elastomer obtained by polymerizing a monomer component containing 1% by mass or more of a styrene monomer or a hydrogenated styrene elastomer is suitable as the micro thermoplastic elastomer (B).
On the other hand, when the content of the styrene monomer exceeds 20% by mass, an elastomer having a large number of styrene units is formed, so that a micro phase separation structure can be formed from the viewpoint of compatibility with the modified polyolefin resin (A-1). It becomes difficult to suppress the whitening phenomenon.

  Commercially available products can be used as the hydrogenated styrene elastomer, such as “Tuff Tech” manufactured by AK Elastomer, “Septon” and “Hibler” manufactured by Kuraray, “Dynalon” manufactured by JSR, Sumitomo “Esporex” manufactured by Kagaku Co., “Clayton G” manufactured by Clayton Polymer, etc. are suitable.

The adhesive resin layer (AR) contains 50 to 99% by mass of the resin composition (A) described above and 1 to 50% by mass of the thermoplastic elastomer (B). Preferably, the resin composition (A) is 75 to 95% by mass, and the thermoplastic elastomer (B) is 5 to 25% by mass. However, the total of the resin composition (A) and the thermoplastic elastomer (B) is 100% by mass.
When the content of the resin composition (A) is less than 50% by mass, the adhesiveness of the adhesive resin layer (AR) to the aluminum foil layer (AL) tends to be lowered. On the other hand, when the content of the resin composition (A) exceeds 99% by mass, it becomes difficult to suppress the whitening phenomenon.

In addition to the resin composition (A) and the thermoplastic elastomer (B), the adhesive resin layer (AR) includes various additives as necessary, for example, flame retardants, slip agents, anti-blocking agents, antioxidants, light You may contain a stabilizer, a tackifier, etc.
1-50 micrometers is preferable and, as for the thickness of an adhesive resin layer (AR), 10-20 micrometers is more preferable.

<Sealant layer (SL)>
The sealant layer (SL) is required to have a sealing property by heat-sealing the exterior material. Generally, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, homo, block, Alternatively, polyolefin resins such as random polypropylene and propylene-α olefin copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, esterified product thereof or ionic cross-linked product thereof can be used. The sealant layer (SL) may be composed of a single layer of a material composed of one or two or more blends as described above, or may form a multilayer structure according to other required performance required as a sealant. Good. The multilayer structure also includes interposing a resin having gas barrier properties such as an ethylene-vinyl acetate copolymer part or a completely saponified product and a polyvinyl acetate copolymer part or a completely saponified product.

  As described above, from the viewpoint of suppressing whitening, it is important to prevent crystallization due to the amount of heat during heat lamination. On the other hand, the reason for performing thermal lamination when manufacturing the exterior material is that the aluminum foil layer (AL) or the corrosion prevention treatment layer (CL) and the adhesive resin layer (AR) are strongly adhered by heat. is there. By strongly adhering these layers, an exterior material excellent in electrolytic solution resistance can be obtained.

  Therefore, as a result of intensive studies to make these layers strongly adhere to each other, the present inventors have found that the adhesion between the aluminum foil layer (AL) or the corrosion prevention treatment layer (CL) and the adhesive resin layer (AR) is as follows: It has been found that the adhesive resin layer (AR) needs to be melted by the amount of heat at the time of thermal lamination. Furthermore, since the sealant layer (SL) does not contribute to the adhesion to the aluminum foil layer (AL) or the corrosion prevention treatment layer (CL) at the time of thermal lamination, it is composed of a polyolefin-based resin or the like. It has been found that the sealant layer (SL) is crystallized and causes a whitening phenomenon.

That is, the present inventors have come to the idea that, although the adhesiveness can be improved as heat is applied from the viewpoint of adhesion, it is preferable not to apply heat as much as possible from the viewpoint of suppressing crystallization. And since the melting point (Tm (AR)) of the adhesive resin layer (AR) and the melting point (Tm (SL)) of the sealant layer (SL) satisfy the following formula (1), the sealant layer (SL) It was found that the adhesion between the aluminum foil layer (AL) or the corrosion prevention treatment layer (CL) and the adhesive resin layer (AR) can be secured while suppressing the crystallization of.
Tm (SL) −Tm (AR) ≧ 10 (1)

When the melting point (Tm (AR)) of the adhesive resin layer (AR) and the melting point (Tm (SL)) of the sealant layer (SL) do not satisfy the above formula (1), the adhesive resin layer (AR) The sealant layer (SL) is easily crystallized by the amount of heat applied. By satisfying the above formula (1), the sealant layer (SL) is not easily melted even by the amount of heat at the time of thermal lamination, and only the adhesive resin layer (AR) is melted to form an aluminum foil layer (AL) or a corrosion prevention treatment layer. Adhesion with (CL) can be improved.
In order to suppress crystallization of the completely melted adhesive resin layer (AR), it is important to contain the above-described micro thermoplastic elastomer (B) in the adhesive resin layer (AR).

The melting point of the adhesive resin layer (AR) and the melting point of the sealant layer (SL) are the melting points when the materials constituting these layers are measured with a differential scanning calorimeter at a heating rate of 10 ° C./min. It is the temperature at which heat reaches a peak.
When the adhesive resin layer (AR) and / or the sealant layer (SL) has a plurality of melting points, the highest temperature is set as the melting point.

  10-100 micrometers is preferable and, as for the thickness of a sealant layer (SL), 20-50 micrometers is more preferable.

<Corrosion prevention treatment layer (CL)>
The corrosion prevention treatment layer (CL) is a layer provided to prevent corrosion of the aluminum foil layer (AL) due to the electrolytic solution or hydrofluoric acid. When providing a corrosion prevention treatment layer (CL), it is calculated | required that it is excellent in adhesiveness with an adhesive resin layer (AR). Therefore, if the adhesiveness between the adhesive resin layer (AR) and the corrosion prevention treatment layer (CL) can be secured with a lower calorific value, it becomes possible to further reduce the calorie at the time of thermal lamination, and in terms of suppressing whitening phenomenon. It becomes effective.

In order to improve the adhesiveness with the adhesive resin layer (AR), the function reacting with the unsaturated carboxylic acid derivative component constituting the modified polyolefin resin (A-1) contained in the adhesive resin layer (AR). A polymer having a group may be contained in the corrosion prevention treatment layer (CL).
In particular, if the polymer having the functional group described above is a cationic polymer, it can provide reactivity due to acid-base interaction, so that it can easily react with an unsaturated carboxylic acid derivative component at a low calorific value. It is preferable because the adhesiveness between the conductive resin layer (AR) and the corrosion prevention treatment layer (CL) can be secured with a low heat quantity.
Examples of the cationic polymer include 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 on an acrylic main skeleton, polyallylamine or a derivative thereof, aminophenol And at least one selected from the group consisting of:

As described above, since the corrosion prevention treatment layer (CL) is provided for the purpose of preventing the corrosion of the aluminum foil layer (AL), the adhesion with the adhesive resin layer (AR) is enhanced by the cationic polymer. However, it is necessary to provide a corrosion prevention function for the aluminum foil layer (AL).
The corrosion prevention treatment layer (CL) may be a single layer or a multilayer. In the case of a single layer, the above-mentioned cationic polymer may be blended into the corrosion prevention treatment layer (CL) itself to form a single layer. On the other hand, in the case of multiple layers, as shown in FIG. 1, the first corrosion prevention treatment layer (CL-1) 14-1 for the purpose of preventing corrosion of the aluminum foil layer (AL) 13 and the purpose of improving adhesion The second corrosion prevention treatment layer (CL-2) 14-2 containing the cationic polymer may be laminated, and the respective purposes are separated.
Here, an example of the multilayer corrosion prevention treatment layer (CL) will be described in detail.

(First corrosion prevention treatment layer (CL-1))
The first corrosion prevention treatment layer (CL-1) is formed by subjecting the aluminum foil layer (AL) to a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, a chemical conversion treatment and the like. Moreover, you may perform combining these processes.
Examples of the degreasing treatment include acid degreasing and alkali degreasing, and 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, if an acid degreasing agent in which a fluorine-containing compound such as monosodium ammonium difluoride is dissolved with the above-described inorganic acid is used, not only the degreasing effect of aluminum but also a passive aluminum fluoride can be formed. It is effective in terms of resistance to hydrofluoric acid. On the other hand, as alkali degreasing, a method using sodium hydroxide or the like can be mentioned.

Examples of the hydrothermal modification treatment include boehmite treatment obtained by immersing aluminum foil in boiling water to which triethanolamine is added.
Examples of the anodizing treatment include alumite treatment.
Examples of the chemical conversion treatment include various chemical conversion treatments including chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or a mixed phase thereof.
These hydrothermal modification treatment, anodizing treatment, and chemical conversion treatment are preferably performed in advance with the above-described degreasing treatment.

  Of the above-described treatments, in particular, the hot water modification treatment and the anodizing treatment easily dissolve the surface of the aluminum foil with a treating agent and further form an aluminum compound (boehmite, anodized, etc.) having excellent corrosion resistance. Therefore, in order to form a co-continuous structure from the aluminum foil layer (AL) to the first corrosion prevention treatment layer (CL-1), it may be included in the definition of the chemical conversion treatment. Without being included in the definition, it is also possible to form the first corrosion prevention treatment layer (CL-1) only by a pure coating technique as described below.

  In other words, the pure coating technique is a material that has an anticorrosion effect (inhibitor effect) for aluminum and is suitable for environmental aspects, and is a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less. It is a method using sol. By using this method, even if it is a general coating method, it becomes possible to form the 1st corrosion prevention process layer (CL-1) which can prevent corrosion of metal foils, such as aluminum foil.

As the rare earth element-based oxide sol, various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based solvents can be used. It is preferable.
In order to stabilize the dispersion of rare earth element-based oxide sols, inorganic acids such as nitric acid, hydrochloric acid and phosphoric acid or salts thereof, or organic acids such as acetic acid, malic acid, ascorbic acid and lactic acid or the like Salt is used as a dispersion stabilizer. Among these dispersion stabilizers, in particular, phosphoric acid or a salt thereof is not only excellent in “sol dispersion stabilization”, but also used the aluminum chelate ability of phosphoric acid in producing the exterior material of the present invention. "Improving adhesion to aluminum foil layer (AL)", "Providing anti-electrolytic solution resistance" by capturing aluminum ions eluted by the influence of hydrofluoric acid, dehydration condensation of phosphoric acid occurs even at low temperatures “Improving the cohesive strength of the oxide layer” is expected due to the ease of use.

Examples of such phosphoric acid or a salt thereof include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. In addition, condensed phosphoric acid such as trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid and ultrametaphosphoric acid, or alkali metal salts and ammonium salts thereof are preferable from the viewpoint of function expression as a packaging material.
In particular, considering the dry film-forming properties (drying capacity, heat quantity) when forming a layer of rare earth element oxide by various coating methods using a rare earth element oxide sol, the reactivity at low temperature is improved. Since an excellent agent is preferable, an Na ion salt having excellent dehydration condensation properties at low temperatures is preferably used as the alkali metal salt.
The salt forming the phosphate is not particularly limited, but is more preferably a water-soluble salt.

When cerium oxide is used as the rare earth element-based oxide and phosphoric acid or a salt thereof is used as the dispersion stabilizer, the blending amount thereof is 1 to 100 parts by mass of phosphoric acid or a salt thereof with respect to 100 parts by mass of cerium oxide. Is preferred. When the blending amount of phosphoric acid or a salt thereof is less than 1 part by mass, the stability of the cerium oxide sol is lowered and it is difficult to satisfy the function as an exterior material. On the other hand, when the blending amount of phosphoric acid or a salt thereof exceeds 100 parts by mass, the function of cerium oxide tends to be lowered.
As for the lower limit of the compounding quantity of phosphoric acid or its salt, 5 mass parts or more are more preferable. On the other hand, the upper limit is more preferably 50 parts by mass or less, and particularly preferably 20 parts by mass or less.

By the way, the oxide layer (first corrosion prevention treatment layer (CL-1)) formed by using the above-mentioned rare earth element-based oxide sol is an aggregate of inorganic particles, and thus undergoes a dry curing step. However, the cohesive strength of the formed oxide layer itself is low. Therefore, in order to supplement the cohesive force of the oxide layer, it is preferable to make a composite with the following anionic polymer.
Specific examples of the anionic polymer include a polymer having a carboxyl group, and examples thereof include poly (meth) acrylic acid (or a salt thereof) or a copolymer containing poly (meth) acrylic acid as a main component.
Components used as a copolymer include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl as alkyl group Alkyl (meth) acrylate monomer as a group; (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (the alkyl group includes a methyl group, an ethyl group, an 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 (alkoxy) As the group, methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol Amide group-containing monomers such as 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, allyl glycidyl ether Glycidyl group-containing monomers such as; silane-containing monomers such as (meth) acryloxypropyltrimethoxysilane and (meth) acryloxypropyltriethoxylane; and isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate Can be mentioned.

  These anionic polymers are materials used to improve the stability of an oxide layer obtained using a rare earth element-based oxide sol as described above. The effect is that the hard and brittle oxide layer is protected with an acrylic resin component, and further, phosphate-derived ion contamination (particularly sodium ions) contained in the sol of rare earth element oxide is trapped. (Cation Catcher) effect is mentioned.

By the way, it is not limited to this invention, For example, in a protective layer provided in order to prevent the corrosion of aluminum foil using a corrosive compound, when alkali metal ions, such as sodium, and alkaline-earth metal ions are contained especially in a protective layer There is a problem that the protective layer is eroded from this ion contamination.
However, if an anionic polymer is used, ion contamination such as sodium ions contained in the rare earth element-based oxide sol described later can be immobilized, so that the resistance of the first corrosion prevention treatment layer (CL-1) is improved. Can be made.

As described above, the anionic polymer is used in combination with a rare earth element-based oxide sol as a component constituting the first corrosion prevention treatment layer (CL-1) in the exterior material, thereby providing the same corrosion prevention performance as the chromate treatment. Can be granted.
As the form of the anionic polymer, a structure in which a water-soluble anionic polymer is crosslinked with a crosslinking agent is preferable.

Examples of the crosslinking agent include compounds having an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group.
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 reacted with polyhydric alcohols such as trimethylolpropane, burettes obtained by reacting with water, or isocyanurates that are trimers, or these polyisocyanates And blocked polyisocyanates obtained by blocking 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, and neopentyl. Epoxy compounds in which epichlorohydrin is allowed to act on glycols such as glycol; epoxy compounds in which polyhydric alcohols such as glycerin, polyglycerol, trimethylolpropane, pentaerythritol, sorbitol and epichlorohydrin are allowed to act; terephthalic acid phthalate, oxalic acid, Examples thereof include an epoxy compound obtained by reacting a dicarboxylic acid such as adipic acid and epichlorohydrin.
Examples of the compound having a carboxyl group include various aliphatic or aromatic dicarboxylic acids, and it is also possible to use poly (meth) acrylic acid or alkali (earth) metal salts of poly (meth) acrylic acid. is there.
As the compound having an oxazoline group, a low molecular compound having two or more oxazoline units, or an acrylic monomer such as (meth) acrylic acid or (meth) acrylic when a polymerizable monomer such as isopropenyl oxazoline is used. Those obtained by copolymerization with an acid alkyl ester, hydroxyalkyl (meth) acrylate, or the like can be used.

  It is also possible to use a silane coupling agent as a cross-linking agent and to selectively react an amine and a functional group so that the cross-linking point is a siloxane bond. 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. In particular, in view of the reactivity with the cationic polymer or a copolymer thereof, epoxy silane, amino silane, and isocyanate silane are preferable as the silane coupling agent.

These crosslinking agents are preferably blended in an amount of 1 to 50 parts by weight, more preferably 10 to 20 parts by weight, based on 100 parts by weight of the cationic polymer. A crosslinking structure becomes inadequate that the compounding quantity of a crosslinking agent is less than 1 mass part. On the other hand, when the compounding amount of the crosslinking agent exceeds 50 parts by mass, there is a risk that the coating pot life is reduced.
The method for crosslinking the water-soluble polymer is not limited to the method using the above-mentioned crosslinking agent, and may be a method for forming a crosslinked structure such as ionic crosslinking using, for example, titanium or a zirconium compound.

  By the way, conventionally, chemical conversion treatment such as chromate treatment has been applied to the aluminum foil in order to impart resistance such as resistance to electrolytic solution, water resistance and hydrofluoric acid to the exterior material. In the chemical conversion treatment, in order to form an inclined structure between the aluminum foil layer (AL) and the chemical conversion treatment layer, the chemical conversion treatment agent blended with hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid or a salt thereof is used for the aluminum foil. As described above, the chemical conversion treatment layer is formed on the aluminum foil by applying a treatment and acting with chromium or a non-chromium compound. Since these chemical conversion treatment agents use an acid, they are accompanied by corrosion of the work environment and coating equipment.

However, as described above, the method of forming the first corrosion prevention treatment layer (CL-1) by the coating technique is different from the chemical conversion treatment represented by the chromate treatment, and therefore, the aluminum foil layer (AL) and the first It is not necessary to form an inclined structure with the corrosion prevention treatment layer (CL-1), and the definition is different from the chemical conversion treatment such as chromate treatment in this respect.
Further, since the properties of the coating agent are not restricted by acidity, alkalinity, and neutrality, it is a treatment method suitable for the working environment. Furthermore, in view of the environmental hygiene of the chromium compound used for chromate treatment, it can be said that the content is interesting from the viewpoint of the corrosion prevention technical field for which an alternative is desired.

(Second corrosion prevention treatment layer (CL-2))
The second corrosion prevention treatment layer (CL-2) includes the above-described cationic polymer, and improves the adhesion between the first corrosion prevention treatment layer (CL-1) and the adhesive resin layer (AR). It is.
Examples of cationic polymers include amine-containing polymers. Specifically, as described above, polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, and a primary amine on an acrylic main skeleton. It is preferably at least one selected from the group consisting of a grafted primary amine-grafted acrylic resin, polyallylamine or a derivative thereof, and aminophenol.

Examples of the polymer having a carboxylic acid that forms an ionic polymer complex with polyethyleneimine include, for example, polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, a copolymer in which a comonomer is introduced, carboxymethylcellulose, or The polysaccharide which has carboxyl groups, such as the ionic salt, is mentioned.
Examples of polyallylamine include homopolymers and copolymers such as allylamine, allylamine amide sulfate, diallylamine, and dimethylallylamine. Furthermore, these amines may be used as free amines, or may be used in the form of a stabilized product with acetic acid or hydrochloric acid. As the copolymer component, maleic acid, sulfur dioxide or the like can be used. Furthermore, it is possible to use a type in which a primary amine is partially methoxylated to impart thermal crosslinkability. It is also possible to use aminophenol.
As these cationic polymers, allylamine or a derivative thereof is particularly preferable.

In the present invention, the cationic polymer has been described as one component constituting the corrosion prevention treatment layer (CL), but this is because the cationic polymer is resistant to electrolyte solution and foot resistance, which is required for an exterior material for a lithium battery. This is because the compound can impart acidity. The reason for this is presumed that the cationic group of the cationic polymer traps fluorine ions (anion catcher), thereby suppressing damage to the aluminum foil.
Moreover, since a cationic polymer is a very preferable compound also from the point of improving the adhesiveness of a 1st corrosion prevention process layer (CL-1) and an adhesive resin layer (AR), a corrosion prevention process layer ( CL) is suitable as one constituent element.

Since the cationic polymer is water-soluble, it is preferably used by forming a crosslinked structure with a crosslinking agent in the same manner as the anionic polymer described above, thereby enabling water resistance to be imparted to the cationic polymer. Become. Examples of the crosslinking agent include the crosslinking agents exemplified above in the description of the anionic polymer.
Therefore, if the cationic polymer forms a cross-linked structure, when a rare earth element-based oxide sol is used as an element constituting the above-described corrosion prevention treatment layer (CL-1), an anionic property is used as the protective layer. Instead of using a polymer, it is possible to use a cationic polymer.

The case where the corrosion prevention treatment layer (CL) is a multilayer has been described above. However, when the corrosion prevention treatment layer (CL) is a single layer, for example, a resin binder such as aminophenol such as a coating type chromate which is a known technique. By using an agent containing phosphoric acid and a chromium compound, a single-layer corrosion prevention treatment layer (CL) having both a corrosion prevention function and adhesion can be formed.
In addition, a coating agent obtained by previously liquefying the rare earth element-based oxide sol and the cationic polymer in advance (that is, a coating liquid in which a material having a corrosion prevention function and a cationic polymer are mixed) is used. Thus, it is possible to form a corrosion prevention treatment layer (CL). However, in this case, it is necessary to consider the stability of the coating liquid.

The corrosion prevention treatment layer (CL) described above is preferably provided in a range of 0.005 to 0.200 g / m ² , more preferably 0.010 to 0.0. The range is 100 g / m ² . When it is thinner than 0.005 g / m ^2, the corrosion prevention function of the aluminum foil layer (AL) may be lowered. On the other hand, when it is thicker than 0.200 g / m ^2, the performance of the corrosion prevention function reaches its peak, and when a rare earth element-based oxide sol is used, if the coating is thick, it is cured by heat during drying ( (Curing) becomes insufficient, and there is a possibility that the cohesive force is reduced.
In the present invention, the thickness of the corrosion prevention treatment layer (CL) is described in terms of mass per unit area. However, when the specific gravity is known, the thickness can be converted from the specific gravity.

  In the exterior material 10 shown in FIG. 1, the corrosion prevention treatment layer (CL) 14 is provided on the adhesive resin layer (AR) 15 side on the aluminum foil layer (AL) 13. For example, the same treatment may be performed on the adhesive layer (AD) 12 side of the aluminum foil layer (AL) 13 to provide the corrosion prevention treatment layer (CL) 14.

<Aluminum foil layer (AL)>
As a material of the aluminum foil layer (AL), a general soft aluminum foil can be used, but an aluminum foil containing iron is used for the purpose of imparting further pinhole resistance and extensibility during molding. preferable. 0.1-9.0 mass% is preferable in 100 mass% of aluminum foil, and, as for content of iron, 0.5-2.0 mass% is more preferable. If the iron content is less than 0.1% by mass, it is difficult to sufficiently impart pinhole resistance and spreadability. On the other hand, when the iron content exceeds 9.0% by mass, flexibility tends to be impaired.
The thickness of the aluminum foil layer (AL) is preferably 9 to 200 μm and more preferably 15 to 100 μm in consideration of barrier properties, pinhole resistance and workability.

Although an untreated aluminum foil may be used as the aluminum foil, it is preferable to use an aluminum foil that has been subjected to a degreasing treatment in terms of imparting resistance to an electrolytic solution. The degreasing treatment is roughly classified into a wet type and a dry type.
Examples of the wet type include acid degreasing and alkali degreasing exemplified above in the description of the first corrosion prevention treatment layer (CL-1). Examples of the acid used for acid degreasing include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. These inorganic acids may be used alone or in combination of two or more. Moreover, from the viewpoint of improving the etching effect of the aluminum foil, various metal salts serving as a supply source of Fe ions, Ce ions, and the like may be blended as necessary. Examples of the alkali used for alkali degreasing include strong etching types such as sodium hydroxide. Moreover, you may use what mix | blended weak alkali type and surfactant. Such degreasing is performed by a dipping method or a spray method.
Examples of the dry type include a method of performing a degreasing process in a process of annealing aluminum. In addition to the degreasing process, a frame process or a corona process may be performed. Furthermore, a degreasing treatment in which pollutants are oxidatively decomposed / removed by active oxygen generated by irradiating ultraviolet rays having a specific wavelength is also included.
In addition, when degreasing the aluminum foil, the degreasing treatment may be performed on only one surface of the aluminum foil, or the degreasing treatment may be performed on both surfaces.

<Adhesive layer (AD)>
Examples of the material constituting the adhesive layer (AD) include a polyurethane resin in which a bifunctional or higher functional isocyanate compound is allowed to act on a main agent such as polyester polyol, polyether polyol, acrylic polyol, and carbonate polyol.
Polyester polyol is an aliphatic dibasic such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, brassylic acid; aromatic dibasic such as isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid One or more acids and aliphatics such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol; cyclohexanediol, hydrogenated It can be obtained using alicyclic systems such as xylylene glycol; and one or more aromatic diols such as xylylene glycol.

  Moreover, as a polyester polyol, the hydroxyl group of the both ends of the polyester polyol obtained using the dibasic acid and diol mentioned above, for example, 2, 4- or 2, 6-tolylene diisocyanate, xylylene diisocyanate, 4, 4 '-Diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, 4, Simple substance of an isocyanate compound selected from 4′-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4′-diisocyanate and the like Or adducts formed of the above isocyanate compounds selected from at least one or more, biuret body, such as a polyester urethane polyol chain extension with isocyanurate products thereof.

As the polyether polyol, it is possible to use an ether-based polyol such as polyethylene glycol or polypropylene glycol, or a polyether urethane polyol in which the above-described isocyanate compound is allowed to act as a chain extender.
As the acrylic polyol, it is possible to use an acrylic resin polymerized using the above-mentioned acrylic monomer.
The carbonate polyol can be obtained by reacting a carbonate compound with a diol. As the carbonate compound, dimethyl carbonate, diphenyl carbonate, ethylene carbonate and the like can be used. On the other hand, as the diol, aliphatic diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol; cyclohexanediol, water Examples thereof include an alicyclic diol such as an added xylylene glycol; a carbonate polyol using a mixture of one or more aromatic diols such as an xylylene glycol, or a polycarbonate urethane polyol subjected to chain extension with the above-described isocyanate compound.

  The various polyols described above can be used alone or in combination of two or more depending on the function and performance required of the exterior material. Moreover, it is also possible to use it as a polyurethane-type adhesive agent by using the isocyanate compound mentioned above as a hardening | curing agent for these main ingredients.

Furthermore, for the purpose of promoting adhesion, a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, or the like may be added to the above-described polyurethane resin.
Examples of the carbodiimide compound include N, N′-di-o-toluylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-di-2,6-dimethylphenylcarbodiimide, N, N′-bis (2, 6-diisopropylphenyl) carbodiimide, N, N′-dioctyldecylcarbodiimide, N-triyl-N′-cyclohexylcarbodiimide, N, N′-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N '-Phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-aminophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N'-di -Cyclohexylcarbodiimide, N, N'-di-p-toluylcarbodiimide and the like.

  Examples of the oxazoline compound include monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, and 2,4-diphenyl-2-oxazoline. 2,2 ′-(1,3-phenylene) -bis (2-oxazoline), 2,2 ′-(1,2-ethylene) -bis (2-oxazoline), 2,2 ′-(1,4 And dioxazoline compounds such as -butylene) -bis (2-oxazoline) and 2,2 '-(1,4-phenylene) -bis (2-oxazoline).

  Examples of epoxy compounds include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, and polyalkylene glycol, sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, and trimethylolpropane. Polyglycidyl ether of aliphatic polyols such as, polyglycidyl ether of alicyclic polyols such as cyclohexanedimethanol, aliphatic and aromatic such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, sebacic acid Diglycidyl ester or polyglycidyl ester of polycarboxylic acid, resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) Dipanidyl or polyglycidyl ether of polyphenols such as lopan, tris- (p-hydroxyphenyl) methane, 1,1,2,2-tetrakis (p-hydroxyphenyl) ethane, N, N′-diglycidylaniline N, N, N-diglycidyl toluidine, N, N, N ′, N′-tetraglycidyl-bis- (p-aminophenyl) methane, N-glycidyl derivatives of amines, triglycidyl derivatives of aminofails, Examples include triglycidyl tris (2-hydroxyethyl) isocyanurate, triglycidyl isocyanurate, orthocresol type epoxy, phenol novolac type epoxy.

  Examples of phosphorus compounds include tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylenephosphonite, bis (2, 4-di-t-butylphenyl) pentaerythritol-di-phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, 2,2-methylenebis (4 6-di-t-butylphenyl) octyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2- Methyl-4-ditridecylphosphite-5-tert-butyl-phenyl) butane, tris (mixed mono and di-nonylphenyl) phosphite, tris ( Nonylphenyl) phosphite, 4,4'-isopropylidenebis (phenyl-dialkyl phosphite) and the like.

  Examples of the silane coupling agent include vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycid. Xylpropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- Various silane coupling agents such as β (aminoethyl) -γ-aminopropyltrimethoxysilane can be used.

Moreover, according to the performance calculated | required by an adhesive agent, you may mix | blend various other additives and stabilizers with the polyurethane resin mentioned above.
1-10 micrometers is preferable and, as for the thickness of an adhesive bond layer (AD), 3-7 micrometers is more preferable.

<Base material layer (SB)>
The base material layer (SB) is provided for the purpose of imparting heat resistance in the sealing process at the time of manufacturing the lithium battery, and for preventing pinholes that may occur during processing and distribution, and it is preferable to use an insulating resin layer. . As such a resin layer, for example, a stretched or unstretched film such as a polyester film, a polyamide film, or a polypropylene film can be used as a single layer or a multilayer film in which two or more layers are laminated.
6-40 micrometers is preferable and, as for the thickness of a base material layer (SB), 10-25 micrometers is more preferable. When the thickness of the base material layer (SB) is less than 6 μm, the pinhole resistance and the insulation are deteriorated. On the other hand, when the thickness of the base material layer (SB) exceeds 40 μm, it becomes difficult to mold the exterior material.

<Method for producing lithium battery exterior material>
Next, although an example of the manufacturing method of the exterior material 10 for lithium batteries shown in FIG. 1 is demonstrated, this invention is not limited to this.
In this example, the step of laminating the corrosion prevention treatment layer (CL) 14 on the aluminum foil layer (AL) 13, the step of bonding the base material layer (SB) 11 and the aluminum foil layer (AL) 13, and the adhesiveness It has the process of further laminating | stacking the resin layer (AR) 15 and the sealant layer (SL) 16, and producing a laminated body, and the process of heat-processing the obtained laminated body.

(Lamination process of corrosion prevention treatment layer (CL) to aluminum foil layer (AL))
This step is a step of forming a corrosion prevention treatment layer (CL) on the aluminum foil layer (AL). As the method, as described above, the aluminum foil layer (AL) is subjected to a degreasing treatment, a hydrothermal alteration treatment, an anodizing treatment, a chemical conversion treatment, or a coating agent having corrosion prevention performance. Is mentioned.
Further, when the corrosion prevention treatment layer (CL) is a multilayer as shown in FIG. 1, for example, the coating liquid (coating agent) constituting the first corrosion prevention treatment layer (CL-1) is used as the aluminum foil layer (AL). ) And baked to form the first corrosion prevention treatment layer (CL-1), and then the coating liquid (coating agent) constituting the second corrosion prevention treatment layer (CL-2) is the first. The second anti-corrosion treatment layer (CL-1) may be coated and baked to form the second anti-corrosion treatment layer (CL-2). The second corrosion prevention treatment layer (CL-2) can also be formed in a laminating step of an adhesive resin layer (AR) and a sealant layer (SL) described later.

For the degreasing treatment, use a spray method or a dipping method.For the hydrothermal conversion treatment or anodizing treatment, use a dipping method.For the chemical conversion treatment, select a dipping method, a spray method, a coating method, etc. according to the type of chemical conversion treatment. Just do it.
Various coating methods such as gravure coating, reverse coating, roll coating, and bar coating can be used as the coating method of the coating agent having corrosion prevention performance.

As described above, the various treatments may be performed on both sides or one side of the aluminum foil, but in the case of single-side treatment, the treated surface is applied to the side on which the adhesive resin layer (AR) layer is laminated.
The coating amount of the coating agent is preferably ^{0.005~0.200g / m 2, 0.010~0.100g / m} 2 is more preferable.
Moreover, when drying cure is required, it can carry out in the range of 60-300 degreeC as base material temperature according to the drying conditions of the corrosion prevention process layer (CL) to be used.

(Bonding process of base material layer (SB) and aluminum foil layer (AL))
This step is a step of bonding the aluminum foil layer (AL) provided with the corrosion prevention treatment layer (CL) and the base material layer (SB) through the adhesive layer (AD). As a method of bonding, methods such as dry lamination, non-solvent lamination, wet lamination, and the like are used, and both are bonded with the material constituting the above-described adhesive layer (AD). Adhesive layer (AD) in the range of 1 to 10 g / ^{m 2} as a dry coating amount, more preferably provided in a range of 3 to 7 g / ^{m 2.}

(Lamination process of adhesive resin layer (AR) and sealant layer (SL))
This step is a step of forming the adhesive resin layer (AR) and the sealant layer (SL) on the corrosion prevention treatment layer (CL) formed by the previous step. As the method, there is a method of sand laminating the adhesive resin layer (AR) together with the sealant layer (SL) using an extrusion laminator.
By this step, as shown in FIG. 1, the base material layer (SB) / adhesive (AD) / aluminum foil layer (AL) / corrosion prevention treatment layer (CL) / adhesive resin layer (AR) / sealant layer ( A laminate in which the layers are laminated in the order of (SL) is obtained.

In addition, the adhesive resin layer (AR) may be laminated directly by an extrusion laminating machine so as to have the above-described material blend composition, or may be laminated in advance by a single screw extruder or a twin screw extruder. The granulated adhesive resin layer (AR) after melt blending using a melt kneader such as a machine or a Brabender mixer may be laminated using an extrusion laminator.
Moreover, when forming a multilayer corrosion prevention treatment layer (CL), if the extrusion laminator is equipped with a unit capable of applying an anchor coat layer, the second corrosion prevention treatment layer ( CL-2) may be applied.

(Heat treatment process)
This step is a step of heat-treating the laminate. By heat-treating the laminate, the adhesion between the aluminum foil layer (AL) / corrosion prevention treatment layer (CL) / adhesive resin layer (AR) / sealant layer (SL) is improved, and more excellent electrolysis resistance Liquidity and hydrofluoric acid resistance can be imparted. However, when heat is applied to the sealant layer (SL) more than necessary, crystallization of the sealant layer (SL) proceeds, and a whitening phenomenon may occur due to distortion during molding.
Therefore, in this step, it is preferable to perform heat treatment to such an extent that crystallization of the sealant layer (SL) is not promoted. The temperature of the heat treatment depends on the types of materials constituting the adhesive resin layer (AR) and the sealant layer (SL), but as a guideline, the maximum temperature of the laminate is 30 to {Tm (SL) +20}. It is preferable to heat-process so that it may become degree C, More preferably, it is 60- {Tm (SL)} degreeC, Most preferably, it is Tm (AR) -Tm (SL) degreeC. If the maximum temperature reached by the laminate is less than 30 ° C., sufficient adhesion between the layers cannot be obtained, and the resistance to electrolytic solution may be lowered. On the other hand, when the maximum temperature of the laminate exceeds {Tm (SL) +20} ° C., crystallization occurs in the sealant layer (SL), and whitening phenomenon easily occurs in the sealant layer (SL).

Although the treatment time of the heat treatment depends on the treatment temperature, it is preferable that the heat treatment is performed for a longer time as the treatment temperature is lower, and the heat treatment is preferably performed in a shorter time as the treatment temperature is higher.
For example, when the treatment temperature is 70 ° C. or lower, it is preferable to perform the heat treatment by storing the laminate for one day or more in an aging chamber adjusted to a predetermined temperature of 70 ° C. or lower.
On the other hand, if the treatment temperature is higher than 70 ° C., it is preferable to perform the heat treatment in a furnace such as a drying furnace or a baking furnace over a period of 30 seconds or more. However, in consideration of productivity and handling, in addition to a drying furnace or baking furnace set to a high temperature (for example, 100 ° C. or higher), a heat treatment method such as thermal lamination or a Yankee drum is used in a short time (for example, less than 30 seconds). Heat treatment is preferred.

As described above, the outer packaging material for a lithium battery of the present invention includes an adhesive resin layer (AR) capable of suppressing crystallization. The adhesive resin layer (AR) is completely melted to improve the adhesion with the corrosion prevention treatment layer (CL), and a specific micro elastomer (B) is blended in the adhesive resin layer (AR). By doing so, the whitening phenomenon of the adhesive resin layer (AR) can be suppressed. Also from such a viewpoint, it is preferable to perform heat treatment so that the maximum temperature of the laminated body is within the above range.
In addition, by performing thermal lamination between the melting points of the adhesive resin layer (AR) and the sealant layer (SL), the aluminum foil layer (AL) or the corrosion prevention treatment layer is suppressed while suppressing the crystallization of the sealant layer (SL). Since the adhesion between (CL) and the adhesive resin layer (AR) can be secured, it can be said that the condition of the above formula (1) is an important requirement from the viewpoint of expanding the process window of thermal lamination.

  Although the Example of this invention is shown below, it is not necessarily limited to this.

[Materials used]
Common materials used in the following examples and comparative examples are as follows.
<Base material layer (SB)>
SB-1: A 25 μm-biaxially stretched polyamide film (manufactured by Unitika) was used.
<Adhesive layer (AD)>
AD-1: A polyurethane-based adhesive (manufactured by Toyo Ink Co., Ltd.) in which an adduct-based curing agent of tolylene diisocyanate was blended with the polyester polyol-based main agent.
<Aluminum foil layer (AL)>
AL-1: An annealed degreased 40 μm-soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., “8079 material”) was used.

<Corrosion prevention treatment layer (CL)>
(CL-1) -1: “Sodium polyphosphate-stabilized cerium oxide sol” adjusted to a solid content concentration of 10 wt% using distilled water as a solvent was used. In addition, 10 mass parts of Na salt of phosphoric acid was mix | blended with respect to 100 mass parts of cerium oxides, and cerium oxide sol was obtained.
(CL-1) -2: 90 wt% of “polyacrylic acid ammonium salt (manufactured by Toagosei Co., Ltd.)” adjusted to a solid concentration of 5 wt% using distilled water as a solvent, and “acryl-isopropenyl oxazoline copolymer ( Nippon Shokubai Co., Ltd.) ”was used.
(CL-1) -3: Using a 1% by weight phosphoric acid aqueous solution as a solvent, the final solution was chromium fluoride (CrF ₃ ) with respect to a water-soluble phenol resin (Sumitomo Bakelite Co., Ltd.) adjusted to a solid content concentration of 1 wt% A chemical conversion treatment agent having a concentration adjusted to 10 mg / m ² as the amount of Cr present in the dry film was used.
(CL-2) -1: 90% by weight of “polyallylamine (manufactured by Nittobo)” adjusted to a solid content concentration of 5 wt% using distilled water as a solvent, and “polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX)” A composition consisting of 10 wt% was used.
(CL-2) -2: “Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd.)” adjusted to a solid content concentration of 5 wt% using distilled water as a solvent, 90 wt%, “polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation) A composition consisting of 10 wt% was used.

<Adhesive resin layer (AR)>
AR-A-1: Random polypropylene (PP) base (Tm (AR) = about 135 ° C.) with respect to 100 parts by mass of a modified polyolefin resin obtained by graft-modifying maleic anhydride, from an ethylene-α olefin copolymer The resin composition (made by Mitsui Chemicals) which mix | blended 15 mass parts of macrophase separation type | mold elastomers (dispersion phase size 0.5-5 micrometers) which become was used.
AR-A-2: Comprising an ethylene-α olefin copolymer with respect to 100 parts by mass of a modified polyolefin obtained by graft-modifying maleic anhydride on a homopolypropylene (PP) base (Tm (AR) = about 165 ° C.). A resin composition (manufactured by Mitsui Chemicals) containing 15 parts by mass of a macrophase separation type elastomer (dispersed phase size 0.5 to 5 μm) was used.
AR-B-1: A polyolefin-based elastomer (manufactured by Mitsui Chemicals, “Notio”) was used.
AR-B-2: A styrene-ethylene / propylene-styrene copolymer (manufactured by AK Elastomer Co., Ltd.) having a styrene content of 12 wt% was used.
AR-B-3: A styrene-ethylene / propylene-styrene copolymer (manufactured by AK Elastomer Co., Ltd.) having a styrene content of 30 wt% was used.

<Sealant layer (SL)>
SL-1: A multilayer film (manufactured by Okamoto) having a total thickness of 30 μm and comprising random PP / block PP / random PP (Tm (SL) = high temperature side melting point of block PP: about 160) ° C).

[Manufacture and evaluation method of exterior materials for lithium batteries]
<Manufacture of exterior materials>
First, the 1st corrosion prevention process layer (CL-1) was provided in the aluminum foil layer (AL) by the micro gravure coat. The coating amount was set to 70 to 100 mg / m ² as a dry coating amount of the coating agent, and baking treatment was performed at 150 to 250 ° C. according to the type of the coating agent in the drying unit.
In addition, about the structure using (CL-1) -1 and (CL-1) -2, the corrosion prevention performance was expressed by compounding these agents, and first, aluminum foil layer (AL (CL-1) -1 and (CL-1) -2 by coating (CL-1) -2 on the layer after coating and baking (CL-1) -1 A composite layer consisting of For (CL-1) -3, this layer was used alone as the first corrosion prevention treatment layer (CL-1).

Next, the aluminum foil layer (AL) provided with the first corrosion prevention treatment layer (CL-1) is attached to the base material layer (SB) by using a polyurethane adhesive (AD-1) by a dry laminating method. Wearing. This is set in the unwinding part of an extrusion laminating machine with an anchor coat coating unit, a sealant layer (SL) is placed on the sand base, and a second corrosion prevention treatment layer (CL-2) is placed on the anchor coat coating unit. Each set was set, and further, the adhesive resin layer (AR) was extruded from the extruder at 290 ° C., thereby producing a laminate by a sand laminating method at a processing speed of 80 m / min. In addition, about the adhesive resin layer (AR), the compound of various materials was created beforehand using the twin-screw extruder, and it used for the said extrusion lamination through the process of water cooling and pelletizing.
The laminated body thus obtained is subjected to heat treatment by thermal lamination so that the maximum temperature of the laminated body is either 160, 170, or 180 ° C., and a lithium battery exterior material is manufactured. The following evaluation was performed.

<Evaluation>
(Measurement of initial strength)
The laminate strength of the lithium battery exterior material was measured using a universal testing machine (Orientec, “Tensilon”) under conditions of a crosshead speed of 300 mm / min.

(Electrolytic solution evaluation 1: Appearance evaluation)
After preparing a solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 so that LiPF ₆ is 1.5 M, an electrolyte is prepared by adding water so that the concentration of water is 1500 ppm. did. This electrolyte solution was filled in a Teflon (registered trademark) container having an internal volume of 250 mL, and a sample was put therein, and after sealing, it was stored at 85 ° C. for 24 hours. The appearance of the sample after storage was evaluated according to the following criteria. In addition, the sample used what cut off the exterior material for lithium batteries in the strip shape of a 100x15 mm size.
○: No floating due to delamination.
X: Floating due to delamination occurred.

(Electrolytic solution evaluation 1: Strength measurement)
The laminate strength of the sample after the electrolytic solution resistance evaluation 1 was measured in the same manner as the initial strength measurement.

(Electrolytic solution evaluation 2: Appearance evaluation)
Except that the storage condition was changed to 85 ° C. and 4 weeks, the same procedure as in the electrolytic solution resistance evaluation 1 was performed. The appearance of the sample after storage was evaluated according to the following criteria.
○: No floating due to delamination.
X: Floating due to delamination occurred.

(Electrolytic solution evaluation 2: measurement of strength)
The laminate strength of the sample after the electrolytic solution resistance evaluation 2 was measured in the same manner as the initial strength measurement.

(Evaluation of electrolyte resistance)
From the measurement results of the strength of the electrolytic solution evaluation 2, the following criteria were used for evaluation.
A: Laminate strength is 5 N / 15 mm or more.
○: Laminate strength is 3 N / 15 mm or more and less than 5 N / 15 mm.
Δ: Laminate strength is 1 N / 15 mm or more and less than 3 N / 15 mm.
X: Laminate strength is less than 1 N / 15 mm.

(Evaluation of whitening)
An outer packaging material for a lithium battery is placed in a cold-molding die having a drawing depth of 5.5 mm of 50 × 30 mm size, and an adhesive resin layer (AR) and a sealant layer ( The presence or absence of whitening of SL) was visually evaluated. The index of whitening was evaluated according to the following criteria by comparing the strained portion (drawn portion) and the unformed portion of the cold-formed sample. In addition, about the part which whitened, it identified by observing the end surface of the sample whitened in the distortion part with an optical microscope.
○: The distorted portion (drawn portion) is at the same level as the unformed portion.
(Triangle | delta): A distortion part (drawing | squeezing part) is whitened slightly from an unshaped part, and a whitening site | part is AR and / or SL.
X: It becomes white so that a distortion part (drawing part) becomes completely cloudy, and a whitening site | part is AR and / or SL.
XX: The peripheral portion (unformed portion) of the distorted portion (drawn portion) is also whitened, and the whitened portion is AR and / or SL.

(Comprehensive evaluation)
The above evaluation results were comprehensively evaluated based on the following criteria.
A: The electrolytic solution resistance evaluation is A, and the whitening evaluation is B.
◯: The electrolytic solution resistance evaluation is ◎ and the whitening evaluation is Δ, or the electrolytic solution resistance evaluation is ◯ and the whitening evaluation is ◯.
△: Evaluation of resistance to electrolytic solution is ◯, evaluation of whitening is △, evaluation of resistance to electrolytic solution is △, evaluation of whitening is ◯, or evaluation of resistance to electrolytic solution is △ The evaluation of whitening is Δ.
X: The electrolytic solution resistance evaluation is Δ, the whitening evaluation is x or xx, or the electrolytic solution resistance evaluation is x.

[Examples 1-15, Comparative Examples 1-6]
Using the materials shown in Table 1, the laminate was heat-treated at the highest temperature shown in Table 1 to produce a lithium battery exterior material, and each was evaluated. The results are shown in Table 2. The maximum temperature reached of the laminate was detected with a thermo label.

  As is clear from Table 2, the exterior materials obtained in Examples 1 to 3 were excellent in electrolytic solution resistance and were able to suppress the whitening phenomenon. In the case of Example 3 where the heat treatment was performed so that the maximum temperature of the laminate was 180 ° C., crystallization of the polypropylene (PP) resin constituting the sealant layer (SL) progressed, and the distortion during cold forming occurred. As a result, a void-craze as shown in FIG. 2 occurs in the block PP portion, and as a result, a slight whitening phenomenon occurs in the sealant layer (SL), but there is no problem in practical use.

Examples 4 to 6 are examples in which the polyolefin elastomer used as the micro thermoplastic elastomer (B) in Examples 1 to 3 was changed to a hydrogenated styrene elastomer.
The exterior materials obtained in Examples 4 to 6 were able to suppress the whitening phenomenon, and were particularly superior in electrolytic solution resistance by using a hydrogenated styrene elastomer as the micro thermoplastic elastomer (B). In Example 6 where heat treatment was performed so that the maximum temperature of the laminate reached 180 ° C., whitening occurred in the sealant layer (SL) as in Example 3, but this was problematic in actual use. There is no degree.

Examples 7-9 are examples in which the styrene content of the hydrogenated styrene elastomer used in Examples 4-6 was increased.
The packaging materials obtained in Examples 7 to 9 showed the same level of electrolytic solution resistance as Examples 4 to 6, but the proportion of styrene was as high as 30 wt%. Although it was inferior compared with Examples 4-6, it is a grade which does not have a problem on actual use.

Examples 10-12 are examples in which the second corrosion prevention treatment layer (CL-2) was not provided in Examples 4-6. From this result, the second corrosion prevention treatment layer (CL-2) Providing (that is, containing a specific cationic polymer in the corrosion prevention treatment layer (CL)) improves adhesion between the adhesive resin layer (AR) and the corrosion prevention treatment layer (CL) by heat treatment of the laminate. It was confirmed that it contributed greatly.
Since the exterior materials obtained in Examples 10 to 12 are not provided with the second corrosion prevention treatment layer (CL-2), the adhesive resin layer (AR) and the corrosion prevention treatment are compared with Examples 1 to 9. The adhesion with the layer (CL) was lowered, and as a result, although the resistance to electrolytic solution was slightly reduced, it was not problematic in actual use. In Example 12 where heat treatment was performed so that the maximum temperature of the laminate reached 180 ° C., a whitening phenomenon occurred in the sealant layer (SL) as in Example 3, but this was problematic in practical use. There is no degree.

Examples 13-15 are the examples which changed the structure of the corrosion prevention process layer (CL) in Examples 4-6.
The packaging materials obtained in Examples 13 to 15 were excellent in resistance to electrolytic solution and could suppress the whitening phenomenon. This result shows that not only the materials used in Examples 1 to 12 but also other materials can solve the problems of the present invention.

On the other hand, Comparative Examples 1-3 is an example which did not mix | blend a micro-type thermoplastic elastomer (B) with the adhesive resin layer (AR) in Examples 1-9.
In the packaging materials obtained in Comparative Examples 1 to 3, the adhesive resin layer (AR) was crystallized by heat during heat treatment of the laminate, and the whitening phenomenon shown in FIG. 2 occurred. In particular, in the case of Comparative Example 3, since the maximum temperature reached when the laminate was heat-treated was high, whitening occurred in the sealant layer (SL), and whitening appeared more remarkably.

Comparative Examples 4 to 6 are examples in which the melting point of the adhesive resin layer (AR) was higher than the melting point of the sealant layer (SL) in Examples 4 to 6 (that is, an example not satisfying the above formula (1)). is there.
Although the exterior material obtained in Comparative Example 6 was able to suppress the whitening phenomenon to the same extent as each Example, the electrolytic solution resistance was inferior to each Example. The improvement in the resistance to electrolytic solution by heat treatment has a correlation with the improvement in the adhesion between the adhesive resin layer (AR) and the sealant layer (SL) in the initial stage. It is preferable to set at a temperature exceeding. Therefore, in the case of Comparative Examples 4 and 5, since the maximum temperature reached of the laminate was in the vicinity of the melting point (160, 170 ° C.) of the adhesive resin layer (AR), the initial adhesion was low, and compared with each Example. As a result, the electrolytic solution resistance was extremely inferior.
In Comparative Example 6 where the heat treatment was performed so that the maximum temperature of the laminate reached 180 ° C., whitening occurred in the sealant layer (SL) as in Example 3.

  Thus, according to the present invention, it is possible to obtain an exterior material for a lithium battery that is excellent in resistance to electrolytic solution and can suppress the whitening phenomenon.

It is sectional drawing which shows an example of the exterior material for lithium batteries of this invention. It is a schematic diagram explaining an example of the mechanism of a whitening phenomenon.

Explanation of symbols

10: Exterior material for lithium battery 11: Base material layer 12: Adhesive layer 13: Aluminum foil layer 14: Corrosion prevention treatment layer 14-1: First corrosion prevention treatment layer 14-2: Second corrosion prevention treatment layer 15: Adhesive resin layer 15a ₁ : Modified polyolefin resin (A-1)
15a ₂ : Macro thermoplastic elastomer (A-2)
15a ₃ : void-clays 16: sealant layer

Claims (7)

In a lithium battery exterior material comprising a laminate in which at least an aluminum foil layer (AL), an adhesive resin layer (AR), and a sealant layer (SL) are sequentially laminated,
The adhesive resin layer (AR) contains 50 to 99% by mass of the resin composition (A) containing the modified polyolefin resin (A-1) and 1 to 50% by mass of the thermoplastic elastomer (B) (however, , The total of the resin composition (A) and the thermoplastic elastomer (B) is 100% by mass), and the thermoplastic elastomer (B) is dispersed phase size with respect to the modified polyolefin resin (A-1). Forms a microphase separation structure in the range of 1 to 200 nm,
The melting point (Tm (AR)) of the adhesive resin layer (AR) and the melting point (Tm (SL)) of the sealant layer (SL) satisfy the following formula (1) (however, the adhesive resin layer: (AR) and / or sealant layer (SL) has a plurality of melting points, the highest temperature is the melting point).
Tm (SL) −Tm (AR) ≧ 10 (1)   In the modified polyolefin resin (A-1), an unsaturated carboxylic acid derivative component derived from an unsaturated carboxylic acid, an acid anhydride of an unsaturated carboxylic acid, or an ester of an unsaturated carboxylic acid is graft-modified to the polyolefin resin. The outer packaging material for a lithium battery according to claim 1, wherein the outer packaging material is a molded resin.   The resin composition (A) is a thermoplastic elastomer (A-2) that forms a macrophase-separated structure in a range where the dispersed phase size exceeds 200 nm and is 50 μm or less with respect to the modified polyolefin resin (A-1). The outer packaging material for a lithium battery according to claim 1, wherein the outer packaging material is contained.   The thermoplastic elastomer (B) is a styrene elastomer or hydrogenated styrene elastomer obtained by polymerizing a monomer component containing 1 to 20% by mass of a styrene monomer. A packaging material for a lithium battery according to claim 1.   The corrosion prevention treatment layer (CL) containing a polymer having a functional group that reacts with the unsaturated carboxylic acid derivative component constituting the modified polyolefin resin (A-1) is formed of the aluminum foil layer (AL) and the adhesive property. The outer packaging material for a lithium battery according to any one of claims 1 to 4, wherein the outer packaging material is laminated between resin layers (AR).   The said polymer is a cationic polymer, The exterior material for lithium batteries of Claim 5 characterized by the above-mentioned.   The cationic polymer is polyethyleneimine, an ionic polymer complex comprising a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is grafted on an acrylic main skeleton, polyallylamine or a derivative thereof, aminophenol It is at least 1 sort (s) chosen from the group which consists of, The lithium battery exterior material of Claim 6 characterized by the above-mentioned.

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