JP5076264B2 - Battery packaging material and battery using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery packaging material having moisture resistance and content resistance used for a battery having a liquid or solid organic electrolyte (polymeric polymer electrolyte) or a fuel cell, a capacitor, a capacitor and the like.
As the battery exterior body, a metal can obtained by pressing a metal into a cylindrical or rectangular parallelepiped container, or a laminate made of a composite film obtained by laminating a plastic film, a metal foil or the like into a bag shape. (Hereinafter referred to as an exterior body) was used.
There were the following problems as a battery outer package. In a metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. Therefore, since the hardware side is designed to match the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom in shape is reduced.
Therefore, it exists in the tendency to use the said bag-shaped exterior body. The material structure of the exterior body includes, for example, at least a base material layer, a barrier layer, an adhesive resin layer, a sealant layer, and an adhesive layer that bonds each of the above layers from the necessary physical properties, workability, economy, and the like as a battery, and protection It consists of layers, and an intermediate layer may be provided as necessary.
A pouch is formed from the laminated body of the above-described configuration of the battery, or at least one side is press-molded to form a battery storage portion to store the battery body, and the pouch type or embossed type (covering the cover) In the above, a necessary part of each peripheral edge is sealed by heat sealing to obtain a battery.
The sealant layer is required to have heat sealability with respect to the lead wire (metal) as well as heat sealability between the sealant layers, and an acid-modified polyolefin resin having metal adhesion is used as the sealant layer (the sealant layer is In the case of a multilayer structure, the innermost resin layer) ensures the adhesion with the lead wire portion.
[0002]
However, when an acid-modified polyolefin resin is laminated as a sealant for an exterior body, it is generally used as a sealant layer for an exterior body because of its inferior processability and high cost compared to a general polyolefin resin. A method has been adopted in which a polyolefin resin layer is used, and a lead wire film that can be thermally bonded to both the sealant layer and the lead wire is interposed in the lead wire portion.
Further, as a packaging material for a battery, in the configuration including the base material layer, the barrier layer, the adhesive resin layer, and the sealant layer, when the sealant layer is formed from a polypropylene-based resin, in the lamination of the barrier layer and the sealant layer Acid-modified polypropylene is used as the adhesive resin layer.
[0003]
[Problems to be solved by the invention]
The acid-modified polypropylene resin as the adhesive resin layer is an extrusion laminator,
Pressurized as a heat-melted state, extruded from a film that becomes a barrier layer and a sealant layer from a T-die, and sandwich-laminated to form a laminate. Alternatively, a laminate may be formed by a coextrusion laminating method together with a resin that forms a sealant layer.
As the adhesive resin layer, when extruding acid-modified polypropylene from a T-shaped die, acid-modified polypropylene (hereinafter referred to as PPa) having a high melt index (hereinafter referred to as high MI) is used in order to ensure the extrusion speed. In the case of the PPa single resin, the neck-in was large during extrusion and the film-forming property was poor. On the other hand, when PPa having a low melt index (hereinafter referred to as low MI) is used, the problem of neck-in is solved, but the extrusion speed does not increase, the film formability is poor, and the thickness varies.
Therefore, usually by blending an appropriate amount of low-density polyethylene (hereinafter referred to as LDPE), a copolymer of ethylene and propylene, a copolymer of ethylene and butene, or a resin component such as butadiene, to the high MI PPa. The film forming property was stabilized.
However, when a packaging material in which each resin is laminated as an adhesive resin layer is packaged as a battery packaging material, cracks may occur at the interface between the acid-modified polypropylene resin and other blended resins. When this occurs, the electrolyte solution penetrates from the crack. At this time, the electrolytic solution may be in direct contact with the barrier layer, thereby breaking the insulation between the battery body, the metal of the lead wire, the barrier layer, generating a potential difference, and forming a through-hole due to corrosion in the barrier layer, The lifetime of the battery may be shortened by the formation of a reaction product of metal ions, which is an electrolyte called dendrite.
An object of the present invention is to provide a laminate structure having good productivity and good content resistance in a battery packaging material comprising a base layer, a barrier layer, a protective layer, an adhesive resin layer, and a sealant.
[0004]
[Means for Solving the Problems]
The above problems can be solved by the following present invention. That is, in the invention described in claim 1, the packaging material for forming the battery outer body in which the battery body is inserted and the peripheral portion is sealed by heat sealing is at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, an adhesive resin layer, a laminate composed of a polypropylene resin sealant layer, polypropylene forming the Rutotomoni the adhesive resin layer such from the adhesive resin layer obtained by blending at least two different kinds of polypropylene resins having melt index resin Ri least one of which is acid-modified polypropylene resin der resin, melt index as a blend resin of packing material for battery, which is a 7~25g / 10 min. In the invention described in claim 2, the adhesive resin layer described in claim 1 is a low melt index polypropylene-based resin having a melt index in the range of 0.3 to 6.0 g / 10 min, and a melt index of 7 to It is formed from a resin obtained by blending two kinds of resins with a polypropylene resin having a high melt index in the range of 30 g / 10 min . In the invention described in claim 3, the laminate described in claim 1 or claim 2 has at least a base material layer, an adhesive layer, a chemical conversion treatment layer (1), aluminum, a chemical conversion treatment layer (2), and an adhesive resin layer. It is composed of a polypropylene resin-based sealant layer . According to a fourth aspect of the present invention, there is provided a battery characterized in that the battery main body is housed and sealed in an exterior body formed of the battery packaging material according to any one of the first to third aspects .
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The battery packaging material of the present invention is a battery packaging body comprising at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, an adhesive resin layer, and a sealant layer having a polypropylene resin-based sealant layer as an acid-modified polyolefin layer. In addition, at least the melt index of the resin forming the adhesive resin layer is in the range of 7 to 25 g / 10 minutes, thereby preventing microcracks generated in the adhesive resin layer. Hereinafter, it will be described in detail with reference to the drawings.
[0006]
FIG. 1 is a diagram for explaining a battery packaging material according to the present invention, in which (a) a cross-sectional view showing a layer configuration example of the battery packaging material, and (b) another layer configuration example of the battery packaging material. It is sectional drawing. FIG. 2 is a cross-sectional view illustrating the layer structure of the sealant of the battery packaging material of the present invention. FIG. 3 is a perspective view for explaining a pouch-type exterior body of a battery. FIG. It is a perspective view explaining the embossed type exterior body of a battery. Figure 5 illustrates the molding in embossed type, (a) a perspective view, (b) embossing the molded outer body, (c) X ₁ -X ₁ part cross-sectional view, with (d) Y ₁ part enlarged view is there. FIG. 6 is a diagram for explaining a method for mounting a lead wire film in bonding a battery packaging material and a lead wire.
[0007]
When laminating a battery packaging material, when the barrier layer and the sealant layer are bonded together by sandwich sandwich method or coextrusion laminate method using acid-modified polypropylene resin as an adhesive resin layer, the molten acid-modified polypropylene resin is coated from a T-die. When extruding into a laminate, if the melt index (hereinafter referred to as MI) is a large acid-modified polypropylene (hereinafter referred to as high MIPPa) of 7 to 30 g / 10 minutes, the neck-in is large and film formation is difficult. However, when an acid-modified polypropylene (hereinafter referred to as low MIPPa) as small as 0.3 to 3 g / 10 min is used, there is a problem that the film-forming speed is lowered, and the film thickness is not uniform, causing difficulty. Conventionally, as a countermeasure, low-density polyethylene (hereinafter, LDPE) is blended with high MIPPa resin.
However, a laminate obtained by laminating a sealant layer using the blend resin as an adhesive resin layer is used as a battery packaging material to form an outer package by embossing, and the battery body is sealed as a lithium ion battery outer package. When packaged, a crack occurs at the interface between the acid-modified polypropylene resin in the embossed and stretched adhesive resin layer and another blended resin (LDPE), and when this crack occurs, the electrolyte solution penetrates from the crack. become. At this time, the electrolytic solution may come into direct contact with the barrier layer, which breaks the insulation between the battery body, the lead wire metal, and the barrier layer, creates a potential difference, and forms a through-hole due to corrosion in the barrier layer. The lifetime of the battery may be shortened by the formation of a reaction product of metal ions, which is an electrolyte called dendrites. That is, as shown in FIG. 7A or FIG. 7B, the adhesive resin layer in the embossing has a high-MI PPaR ₁ and LDPER ₅ with a sea-island structure, and microcracks MC are formed on the periphery of LDPER _5. Causes of the electrolyte solution penetrating into the microcrack MC generated in the adhesive resin layer 13 to deteriorate the insulation, reach the barrier layer surface, corrode the barrier layer, and generate a reaction product with the electrolyte solution It was confirmed that
[0008]
As a result of diligent research on the corrosion of the barrier layer, the present inventors have found that the high MIPPa resin and the LDPE resin constituting the adhesive resin layer have a sea-island structure as shown in FIGS. 7 (a) and 7 (b). next, high MI PPAR ₁ and LDPER ₅ elongation minute cracks from differences in the surface of the low-density polyethylene (hereinafter microcracks MC) is generated, this phenomenon exacerbate insulating adhesive resin, also, It has been confirmed that this causes corrosion of the barrier layer and generation of a reaction product with the electrolytic solution. Moreover, this microcrack MC can be confirmed as a whitening phenomenon by visual confirmation.
As a result of further research on the method of preventing the occurrence of the microcrack MC, MI = 7 to 25 g / 10 min so that the adhesive resin layer 13 is a blend of two or more polypropylene resins and the final blend resin has an MI of 7 to 25 g / 10 min. A resin obtained by blending at least two kinds of resins, that is, a low MIPP resin of 0.3 to 6.0 g / 10 min and a high MI PP resin of MI = 7 to 30 g / 10 min, The occurrence of the microcrack MC is prevented by using any one of PPa, and a sandwich lamination method or a coextrusion lamination method using an adhesive resin layer as a barrier layer and a sealant layer in the lamination processing of battery packaging materials When the molten adhesive resin layer is extruded from the T-die to the material to be laminated, the neck-in can be reduced and stable. Which resulted in the completion of the present invention found that it is.
[0009]
Regarding the composition of the adhesive resin layer in the battery packaging material of the present invention, more specifically, at least one PP resin is acid-modified polypropylene, and a high MI PP resin and a low MI PP resin When the apparent MIF as a blend resin is 7 to 25 g / 10 min, the occurrence of microcracks can be prevented, and the neck-in during film forming can be reduced, enabling stable production.
Here, the polypropylene resin used in the present invention may be a homo-type polypropylene, a random-type polypropylene, a block-type polypropylene, or a terpolymer resin that is a copolymer of propylene, ethylene, and butene. Further, the MI measurement method can be distinguished according to JIS K7210. The acid modification means that an unsaturated carboxylic acid is graft-polymerized.
The apparent MI and F are the blending resin A (MI = m1) and the blending resin B (m2), and the weight ratio of the blend is A: B = x: y, F = m1 × x / ( x + y) + m2 × y / (x + y)
The value obtained by
For example,
PP (MI = 0.5) <4> + PPa (MI = 18) <6> F = 11
PPa (MI = 1) <1> + PP (MI = 18) <9> F = 16.3
PPa (MI = 3) <2> + PPa (MI = 10) <8> F = 8.6
[Abbreviation PP: Polypropylene resin, the number in <> after the abbreviation is a number indicating the blend ratio. ]
[0010]
As described above, as a resin used for the adhesive resin layer, a high MI PP (PPa) alone is difficult to form a neck-in at the time of film formation, but a low MI PP (PPa) is added to a high MI PP (PPa). ), The neck-in is reduced, and the film can be formed without any problem. In addition, micro-cracks were not formed in the adhesive resin layer, the insulating property of the adhesive resin layer was maintained, the corrosion of the barrier layer was prevented, and the battery performance was stabilized.
[0011]
As shown in FIG. 1A, the battery packaging material of the present invention is a laminate composed of at least a base material layer 11, an adhesive layer 16, aluminum 12, a chemical conversion treatment layer 15, an adhesive layer 13d, and a multilayer sealant layer 14. When the exterior body to be described later is an embossed type, as shown in FIG. 1B, the laminate is a base material layer 11, an adhesive layer 16, a chemical conversion treatment layer 15 (1), aluminum. 12, the chemical conversion treatment layer 15 (2), the adhesive layer 13 d, and the multilayer sealant layer 14 are desirable.
[0012]
In the present invention, when the battery packaging material is laminated, the chemical conversion treatment layer provided on the barrier layer and the sealant layer are bonded by a sandwich lamination method using an adhesive resin layer or a coextrusion lamination method.
In this case, in order to prevent delamination due to hydrofluoric acid generated by the reaction between the electrolytic solution and moisture in a lithium ion battery or the like, it is desirable to perform an adhesion stabilization treatment described below.
[0013]
For example, as shown in FIG. 1A, the base layer 11 and one side of the barrier layer 12 are dry-laminated 16 and the acid-modified polyolefin 13 is extruded to the other side (the chemical conversion layer 15) of the barrier layer 12. When the sealant layer 14 is sandwiched and laminated, or the acid-modified polyolefin resin 13 and the sealant layer 14 are coextruded to form a laminate, the resulting laminate is made to have a softening point higher than that of the acid-modified polypropylene resin 13. By heating to such a condition, a laminate having a predetermined adhesive strength can be obtained.
The chemical conversion treatment layer 15 on the surface of the barrier layer may be provided on both surfaces of the barrier layer 12 as shown in FIG.
Specific examples of the heating method include a hot roll contact method, a hot air method, a near or far infrared method, and any heating method may be used in the present invention, and the adhesive resin is softened as described above. What is necessary is just to be able to heat above the point temperature.
[0014]
As another method, the adhesive strength can also be increased by heating the aluminum 12 to a condition where the surface temperature of the sealant layer side of the aluminum 12 reaches the softening point of the acid-modified polypropylene resin during the sandwich lamination or coextrusion lamination. It can be set as the stable laminated body.
[0015]
As the polypropylene used for the sealant layer of the present invention, homo-type polypropylene, random-type polypropylene, block-type polypropylene, terpolymer resin which is a copolymer of propylene, ethylene and butene can be used. Moreover, acid-modified polypropylene can also be used. As the acid-modified polypropylene resin, a random type polypropylene, a homotype polypropylene, or a block type polypropylene grafted with an unsaturated carboxylic acid can be used.
In addition, the sealant layer may be a single layer made of the above resin, or a multilayer film made of two kinds of resins selected from the above resins, for example, S2 and S3 as shown in FIG. Alternatively, it may be a two-layered structure or a three-layered structure composed of S1, S2, and S3 as shown in FIG.
[0016]
The battery lead wire is made of an elongated plate-like or rod-like metal, and the plate-like lead wire has a thickness of about 50 to 2000 μm and a width of about 2.5 to 20 mm. AL, Cu (including Ni plating), Ni, and the like.
[0017]
When the acid-modified polypropylene resin is used as the sealant layer of the battery packaging material of the present invention, the acid-modified polypropylene has adhesiveness to the metal and can be heat sealed to the lead wire, but adheres to the metal. When the sealant layer is made of a polypropylene resin that does not have the property, it is for lead wires that have heat sealability between the battery lead wire part and the exterior body between the battery lead wire part and the exterior body at the time of hermetically sealing. It is necessary to interpose a film.
A lead wire film 6 is interposed between the outer package 5 and the lead wire 4, and a specific method thereof is, for example, as shown in FIGS. 6 (a) and 6 (b), the lead wire of the battery body 2. The lead wire film 6 is placed above and below the sealing seal portion 4 (actually fixed by a temporary seal) and inserted into the outer package 5 and sealed by heat sealing in a state where the lead wire portion is sandwiched. As a method for interposing the lead wire film 6 in the lead wire 4, the lead wire film 6 may be wound around a predetermined position of the lead wire 4 as shown in FIG. 6 (d) or 6 (e). Good.
[0018]
When the lead wire film is used, specifically, a film made of acid-modified polypropylene having thermal adhesiveness is used for both the sealant layer and the lead wire. As the acid-modified polypropylene resin, unsaturated carboxylic graft polypropylene can be used.
[0019]
The layer thickness of the lead wire film 20 only needs to be 1/3 or more of the thickness of the lead wire used. For example, if the lead wire has a thickness of 100 μm, the total thickness of the lead wire film 20 May be approximately 30 μm or more.
[0020]
The battery packaging material forms an outer package for packaging the battery body. Depending on the type of the outer package, a pouch type as shown in FIG. 3 and FIGS. 4 (a), 4 (b) or FIG. There is an emboss type as shown in 4 (c). The pouch type includes three-side seals, four-side seals, and pillow types such as a pillow type. FIG. 3 illustrates a pillow type.
As shown in FIG. 4 (a), the embossed type may be formed with a recess on one side, or as shown in FIG. Four sides may be heat sealed. There is also a type in which a concave portion is formed on both sides with a folding portion as shown in FIG. 4 (c), the battery is accommodated, and three sides are heat-sealed.
When the battery packaging material is an embossed type, as shown in FIGS. 5 (a) to 5 (d), the laminated packaging material 10 is press-molded to form the recess 7.
[0021]
Next, each layer which comprises the battery packaging material of this invention is demonstrated.
The base material layer 11 in the outer package is made of stretched polyester or nylon film. At this time, examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester, polycarbonate, and the like. Can be mentioned. Examples of nylon include polyamide resin, that is, nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like.
When the base material layer 11 is used as a battery, the base material layer 11 is a part that comes into direct contact with the hardware. Considering the existence of pinholes in a single film and the generation of pinholes during processing, the base material layer needs to have a thickness of 6 μm or more, and a preferred thickness is 12 to 30 μm.
[0022]
The base material layer 11 can also be laminated in order to improve pinhole resistance and insulation when used as a battery outer package.
When the base material layer is laminated, the base material layer includes at least one resin layer of two or more layers, and the thickness of each layer is 6 μm or more, preferably 12 to 30 μm. Examples of laminating the base material layer include the following 1) to 8).
1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched stretched polyethylene terephthalate In addition, packaging material mechanical suitability (transport stability in packaging machines and processing machines), surface protection (heat resistance, electrolyte resistance) ) When the battery exterior body is made an embossed type as a secondary processing, the base material layer is protected when the embossing is applied for the purpose of reducing the frictional resistance between the mold and the base material layer during embossing. In order to achieve this, the base material layer may be multilayered, and a fluororesin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, or a resin layer made of a blend thereof may be provided on the surface of the base material layer. preferable.
For example,
3) Fluorine resin / stretched polyethylene terephthalate (Fluorine resin is a film or formed by drying after liquid coating)
4) Silicone resin / stretched polyethylene terephthalate (silicone resin is a film or formed by drying after liquid coating)
5) Fluorine-based resin / stretched polyethylene terephthalate / stretched nylon 6) Silicone-based resin / stretched polyethylene terephthalate / stretched nylon 7) Acrylic resin / stretched nylon (Acrylic resin is film-like or cured after drying by liquid coating)
8) Acrylic resin + polysiloxane graft acrylic resin / stretched nylon (acrylic resin is film-like or cured by drying after liquid coating)
[0023]
The barrier layer 12 is a layer for preventing water vapor from entering the inside of the battery from the outside, stabilizing the pinhole and processability (pouching, embossing formability) of the barrier layer alone, and being resistant to resistance. In order to have a pinhole, a metal such as aluminum or nickel having a thickness of 15 μm or more, or a film on which an inorganic compound such as silicon oxide or alumina is deposited may be used. The aluminum is 80 μm.
In order to further improve the generation of pinholes and to make the battery exterior body type an embossed type, in order to prevent the occurrence of cracks in the embossing molding, the present inventors have made a material for aluminum used as a barrier layer. However, when the iron content is 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight, the extensibility of aluminum is better than that of aluminum not containing iron. The present inventors have found that the occurrence of pinholes due to bending is reduced as a laminate, and the side wall can be easily formed when the embossed type exterior body is formed. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement of embossing formability are not observed, and the iron content of the aluminum exceeds 9.0% by weight. In such a case, the flexibility as aluminum is hindered, and the bag-making property is deteriorated as a laminate.
[0024]
In addition, aluminum produced by cold rolling changes its flexibility, waist strength and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in the present invention is harder than the non-annealed hard-treated product. Aluminum which tends to be soft with some or complete annealing is preferred.
The degree of flexibility, waist strength, and hardness of aluminum, that is, the conditions for annealing, may be appropriately selected in accordance with processability (pouching, embossing). For example, in order to prevent wrinkles and pinholes during embossing, it is desirable to use soft aluminum annealed according to the degree of forming.
[0025]
The present inventors have been able to obtain a laminate that is satisfactory as the packaging material by subjecting the front and back surfaces of aluminum, which is the barrier layer 12 of the battery packaging material, to chemical conversion. Specifically, the chemical conversion treatment is to form an acid-resistant film such as phosphate, chromate, fluoride, triazine thiol compound, etc. Among the acid-resistant film-forming substances, phenol resin, chromium fluoride (3) Phosphoric acid chromate treatment using a compound and three components of phosphoric acid is good. Or the chemical conversion treatment agent which contains metals, such as molybdenum, titanium, a zircon, or a metal salt in the resin component containing a phenol resin at least was favorable. Due to the formation of the acid-resistant film, delamination between aluminum and the base material layer during embossing is prevented, and the aluminum surface is dissolved and corroded by hydrogen fluoride generated by the reaction between the battery electrolyte and moisture. In particular, the aluminum oxide existing on the surface of aluminum is prevented from being dissolved and corroded, and the adhesion (wetting property) of the aluminum surface is improved, and the base material layer 11 and the aluminum 12 at the time of embossing and heat sealing. The effect of preventing delamination on the inner surface of aluminum by hydrogen fluoride generated by the reaction between electrolyte and moisture was obtained.
As a result of conducting a chemical conversion treatment on the aluminum surface using various substances and studying the effect thereof, among the acid-resistant film forming substances, it is composed of three components of a phenol resin, a chromium fluoride (3) compound, and phosphoric acid. The treatment with phosphoric acid chromate using the sample was good.
Or the chemical conversion treatment agent which contains metals, such as molybdenum, titanium, a zircon, or a metal salt in the resin component containing a phenol resin at least was favorable.
[0026]
When the exterior body is a pouch type, the chemical conversion treatment of aluminum may be performed on one side only on the sealant layer side or on both sides of the base material layer side and the sealant layer side. When the battery outer body is an embossed type, delamination between the aluminum and the base material layer during embossing can be prevented by subjecting both surfaces of the aluminum to chemical conversion treatment.
[0027]
The sealant layer in the battery packaging material of the present invention is composed of a polypropylene resin as described above. Polypropylene resin is a single layer or multilayer structure made of polypropylene such as homo-type polypropylene, random-type polypropylene, block-type propylene, or acid-modified polypropylene. When at least the innermost layer is made of the acid-modified polypropylene resin, it is not necessary to interpose a lead wire film between the outer package and the lead wire when the battery is hermetically packaged.
[0028]
【Example】
The battery packaging material of the present invention will be described more specifically with reference to examples.
(1) Configuration of battery packaging material The following configurations were used in both the examples and comparative examples.
ON 25 μm / DL 3 μm / Double-side chemical conversion treatment ALM 40 μm / Adhesive resin 15 μm / Sealant: 30 μm
[Abbreviation ON: biaxially stretched nylon film, DL: dry laminate, ALM: aluminum]
The acid-modified polypropylene was unsaturated carboxylic acid grafted random propylene, and the sealant was a film or extruded layer made of random polypropylene resin. The blend ratio in the case where an adhesive resin is used as a blend resin, described in Examples and Comparative Examples, is parts by weight.
(2) The chemical conversion treatment applied to the barrier layer of the chemical conversion treatment exterior body was carried out by using a roll coating method with an aqueous solution comprising a phenol resin, a chromium fluoride (3) compound, and phosphoric acid as the treatment liquid in both the examples and the comparative examples. The film was baked under the condition that the film temperature was 180 ° C. or higher. The application amount of chromium is 1 mg / m ² (dry weight).
(2) Type of exterior body Each of the examples and comparative examples was evaluated as an embossed type exterior body. The shape was a single-sided embossed type, and the shape of the concave portion (cavity) of the mold was 30 mm × 50 mm and the depth was 3.5 mm, and the moldability was evaluated by press molding. In each of the embossed type examples, an embossed laminate not molded was used as a lid.
[Example 1]
Chemical conversion treatment was performed on both sides of 40 μm aluminum, and a stretched nylon film (thickness: 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. Thus, in a state of being heated above the softening point of the polypropylene resin that is an adhesive resin, an adhesive resin described later is extruded and 30 μm of a polypropylene film serving as a sealant layer is sandwich-laminated to obtain a laminate.
The adhesive resin was a resin obtained by blending 74 parts of acid-modified polypropylene with an MI of 30 g / 10 min and 26 parts of polypropylene with an MI of 0.5 g / 10 min. MI as a blend resin is 20 g / 10 min.
The obtained laminate was used as a tray by embossing, and an unmolded laminate was used as a cover material as an exterior.
[Example 2]
Chemical conversion treatment was applied to both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. Was laminated with a polypropylene film serving as a sealant layer to form a primary laminate.
The adhesive resin was a resin obtained by blending 60 parts of acid-modified polypropylene with an MI of 26 g / 10 min and 40 parts of acid-modified polypropylene with an MI of 1.0 g / 10 min. MI as a blend resin is 16 g / 10 min.
The primary laminate was heated to a temperature equal to or higher than the softening point of the adhesive resin with hot air to obtain a secondary laminate, and a tray by embossing, and an unmolded secondary laminate was used as a lid.
[Example 3]
Chemical conversion treatment was performed on both sides of 40 μm aluminum, and a stretched nylon film (thickness: 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. As described above, a laminated body was obtained by coextrusion laminating a later-described adhesive resin and a polypropylene resin serving as a sealant layer in a state of being heated to a temperature higher than the softening point of the polypropylene resin as an adhesive resin.
The adhesive resin was a resin obtained by blending 40 parts of polypropylene of MI 18 g / 10 min and 60 parts of acid-modified polypropylene of MI 3.0 g / 10 min. MI as a blend resin is 9 g / 10 min.
The obtained laminate was embossed to form a tray, and the unmolded laminate was used as a cover material to form an exterior body.
[Example 4]
Both surfaces of aluminum 40 μm are subjected to chemical conversion treatment, and a stretched nylon film (thickness 25 μm) is bonded to one surface of the chemical conversion treatment by a dry laminating method. Next, the adhesive resin described later is attached to the other surface of the chemical conversion treatment aluminum. And the polypropylene resin used as a sealant layer was coextrusion laminated to obtain a primary laminate.
The adhesive resin was a resin obtained by blending 84 parts of acid-modified polypropylene with MI 8 g / 10 min and 16 parts of polypropylene with MI 2.0 g / 10 min. MI as a blend resin is 8 g / 10 min.
The primary laminate was heated to a temperature equal to or higher than the softening point of the adhesive resin with hot air to obtain a secondary laminate, and a tray by embossing, and an unmolded secondary laminate was used as a lid.
[0029]
[Comparative Example 1]
Chemical conversion treatment was applied to both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. A primary laminate was obtained by sandwich-laminating a polypropylene film as a sealant layer with an adhesive resin of 15 μm.
The adhesive resin was a resin obtained by blending 90 parts of acid-modified polypropylene with MI 18 g / 10 min and 10 parts of low density polyethylene. MI as a blend resin is 17 g / 10 min.
The primary laminate was heated to a temperature equal to or higher than the softening point of the adhesive resin with hot air to obtain a secondary laminate, and a tray by embossing, and an unmolded secondary laminate was used as a lid.
[Comparative Example 2]
Chemical conversion treatment was performed on both sides of 40 μm aluminum, and a stretched nylon film (thickness: 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. Thus, in a state of being heated above the softening point of the polypropylene resin that is an adhesive resin, an adhesive resin described later is extruded and 30 μm of a polypropylene film serving as a sealant layer is sandwich-laminated to obtain a laminate.
The adhesive resin was 100 parts of acid-modified polypropylene resin with an MI of 10 g / 10 min.
Using the obtained laminate, a tray was embossed to form a tray, and an unmolded laminate was used as a cover material to form an exterior.
[Comparative Example 3]
A stretched nylon film (thickness 25 μm) is bonded to one surface of aluminum 40 μm that is not subjected to chemical conversion treatment by a dry laminating method. Next, a resin described later is used as an adhesive resin 15 μm on the other surface of the aluminum, and a sealant layer and The resulting polypropylene film was sandwich-laminated to form a primary laminate.
The adhesive resin was a resin obtained by blending 60 parts of acid-modified polypropylene resin with an MI of 26 g / 10 min and 40 parts of polypropylene with an MI of 1.0 g / 10 min. MI as a blend resin is 17 g / 10 min.
The primary laminate was heated to a temperature equal to or higher than the softening point of the adhesive resin with hot air to form a secondary laminate and embossed to form a tray, and the non-molded secondary laminate was used as a lid to form an exterior.
[0030]
<Evaluation items>
1) Whitening of the adhesive resin layer: by visual confirmation.
2) MC in adhesive resin layer: By confirming the cross section with a transmission electron microscope (x2000).
3) Insulation: The electrolyte solution was filled, and the resistance value between the barrier layer and the electrolyte solution was measured at 25V. The electrolyte was measured by filling 3 g of a mixed solution of ethylene carbonate, diethyl carbonate and dimethyl carbonate (1: 1: 1) so as to be 1M LiPF ₆ .
4) Delamination: Filled with 3 g of a mixed solution of ethylene carbonate, diethyl carbonate and dimethyl carbonate (1: 1: 1) adjusted to 1M LiPF ₆ and kept at a temperature of 85 ° C. for 7 days. The delamination between the adhesive resin layers was visually confirmed.
[0031]
<Result>
In each of Examples 1 to 4, there was no whitening or microcracking in the adhesive resin layer, and the insulation was maintained. Further, no delamination between the ALM and the adhesive resin layer was observed. In addition, the neck-in at the time of extrusion was small, and the film forming property was stable.
In Comparative Example 1, both whitening and microcracks were observed in the adhesive resin layer, and the resistance value between the barrier layer and the electrolytic solution was 1.0 MΩ, and the insulation was broken.
In Comparative Example 2, there was no whitening or microcracking in the adhesive resin layer, and the insulation was maintained, but the neck-in at the time of lamination was large, the thickness variation was large, and the film forming property was stable. There wasn't. In Comparative Example 3, there was no whitening or microcracking in the adhesive resin layer and insulation was maintained, but delamination occurred between ALM and the adhesive layer resin.
[0032]
【Effect of the invention】
The battery packaging material is a laminate composed of a base material layer, a barrier layer, a chemical conversion treatment layer, an adhesive resin layer, and a polypropylene sealant layer. The adhesive resin layer is extruded to sandwich the sealant layer, and the sealant layer is formed by coextrusion lamination. When laminated, the composition of the adhesive resin layer is a blend resin of a polypropylene resin with a high MI and a polypropylene resin with a low MI to prevent aluminum corrosion due to microcracks generated in the adhesive resin layer. It became possible. .
Moreover, the chemical conversion treatment applied to both sides of the aluminum of the exterior body can prevent the occurrence of delamination between the base material layer and the aluminum during embossing and heat sealing. When formed by sandwich lamination method or coextrusion lamination method, the aluminum surface by hydrogen fluoride generated by the reaction between the electrolyte of the battery and moisture by heating at the time of forming the laminated body or by heating after forming the laminated body By being able to prevent corrosion, it is an exterior body that can also prevent delamination between aluminum and the content-side layer.
[Brief description of the drawings]
1A and 1B are diagrams illustrating a battery packaging material according to the present invention, wherein FIG. 1A is a cross-sectional view showing an example of a layer structure of a battery packaging material, and FIG. 1B is another layer structure example of a battery packaging material. It is sectional drawing.
FIG. 2 is a cross-sectional view illustrating a layer structure of a sealant of a battery packaging material according to the present invention.
FIG. 3 is a perspective view for explaining a pouch-type exterior body of a battery.
FIG. 4 is a perspective view illustrating an embossed type exterior body of a battery.
[5] will be described molding in embossed type, (a) a perspective view, (b) embossing the molded outer body, (c) X ₁ -X ₁ part cross-sectional view, with (d) Y ₁ part enlarged view is there.
FIG. 6 is a diagram for explaining a method for attaching a lead wire film in bonding a battery packaging material and a lead wire.
7A is a cross-sectional view of a battery packaging material, and FIG. 7B is an enlarged view of a Y ₂ portion for explaining generation of microcracks in an adhesive resin layer having a conventional composition.
[Explanation of symbols]
R ₁ high MIPPa
R ₂ Low MIPPa
R ₃ high MIPP
R ₄ low MIPP
R ₅ Low density polyethylene R ₆ Rubber component MC Micro crack 1 Battery 2 Battery body 3 Cell (power storage unit)
4 Lead wire (electrode)
DESCRIPTION OF SYMBOLS 5 Exterior body 6 Lead wire film 7 Recessed part 8 Side wall part 9 Seal part 10 Laminated body (battery packaging material)
11 Base material layer 12 Aluminum (barrier layer)
DESCRIPTION OF SYMBOLS 13 Adhesive resin layer 14 Sealant layer S1 Outer layer S2 of sealant layer Intermediate layer S3 of sealant layer Inner layer 15 of sealant layer Chemical conversion treatment layer 16 Substrate side dry laminate layer 20 Press molding part 21 Male mold 22 Female mold 23 Cavity

Claims (4)

The packaging material that forms the battery outer body in which the battery body is inserted and the periphery is sealed by heat sealing is composed of at least a base material layer, an adhesive layer, aluminum, a chemical conversion treatment layer, an adhesive resin layer, and a polypropylene resin sealant layer. that a laminate, the polypropylene resin forming the Rutotomoni the adhesive resin layer such from the adhesive resin layer obtained by blending at least two different kinds of polypropylene resins having melt index resin least one of which is an acid modified polypropylene resin Ah it is, packaging material for a battery, wherein the melt index of the blend resin is 7~25g / 10 min. An adhesive resin layer comprising: a low melt index polypropylene resin having a melt index in the range of 0.3 to 6.0 g / 10 min; and a high melt index polypropylene resin having a melt index in the range of 7 to 30 g / 10 min; The battery packaging material according to claim 1, wherein the battery packaging material is formed from a resin obtained by blending two kinds of resins . The laminate is composed of at least a base material layer, an adhesive layer, a chemical conversion treatment layer (1), aluminum, a chemical conversion treatment layer (2), an adhesive resin layer, and a polypropylene resin sealant layer. The battery packaging material according to claim 1 or claim 2 . A battery, wherein the battery body is housed and sealed in an exterior body formed of the battery packaging material according to any one of claims 1 to 3 .

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