JP7056483B2 - Adhesive film and battery for metal terminals - Google Patents

Description

The present invention relates to an adhesive film for metal terminals and a battery.

Conventionally, various types of batteries have been developed, but packaging materials are indispensable members for encapsulating battery elements such as electrodes and electrolytes in all batteries. Conventionally, metal packaging materials have been widely used for battery packaging, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have various shapes. At the same time, there is a demand for thinner and lighter weight. However, the metal packaging material, which has been widely used in the past, has a drawback that it is difficult to keep up with the diversification of shapes and there is a limit to weight reduction.

Therefore, in recent years, as a packaging material that can be easily processed into various shapes and can be made thinner and lighter, it is in the form of a film in which a base material layer / adhesive layer / barrier layer / heat-sealing resin layer is sequentially laminated. Laminates have been proposed. When such a film-shaped packaging material is used, the peripheral portions of the packaging material are heat-sealed by heat-sealing with the heat-sealing resin layers located in the innermost layer of the packaging material facing each other. , The packaging material seals the battery element.

A metal terminal protrudes from the heat-sealed portion of the packaging material, and the battery element sealed by the packaging material is electrically connected to the outside by the metal terminal electrically connected to the electrode of the battery element. That is, of the portions where the packaging material is heat-sealed, the portion where the metal terminals are present is heat-sealed with the metal terminals sandwiched between the heat-sealing resin layers. Since the metal terminal and the heat-sealing resin layer are made of different materials, the adhesion tends to decrease at the interface between the metal terminal and the heat-sealing resin layer.

Therefore, an adhesive film may be arranged between the metal terminal and the heat-sealing resin layer for the purpose of enhancing the adhesion thereof.

Japanese Unexamined Patent Publication No. 2015-79638

In addition to high adhesion to the packaging material and metal terminals, such an adhesive film is also required to have excellent resistance to the electrolytic solution sealed by the packaging material.

Under such circumstances, it is a main object of the present invention to provide an adhesive film for metal terminals, which has high adhesion to packaging materials and metal terminals and is also excellent in electrolytic solution resistance. Further, it is also an object of the present invention to provide a battery using the adhesive film for metal terminals.

The present inventors have made diligent studies to solve the above problems. As a result, it is an adhesive film for metal terminals, which is interposed between the metal terminal electrically connected to the electrode of the battery element and the packaging material for sealing the battery element, and is an adhesive film for metal terminals. However, the polypropylene layer is composed of a laminate including at least one polypropylene layer and at least one acid-modified polypropylene layer, and the acid-modified polypropylene layer forms a surface layer on at least one side of the adhesive film for metal terminals. The polypropylene layer has a sea-island structure when the cross section is observed by an electron micrograph, and the total thickness of the polypropylene layer is 0 when the total thickness of the acid-modified polypropylene layer is 1. It has been found that the adhesive film for metal terminals in the range of 7 or more and 3.5 or less has high adhesion to the packaging material and the metal terminals, and is also excellent in electrolytic solution resistance. The present invention has been completed by further studies based on such findings.

That is, the present invention provides the inventions of the following aspects.
Item 1. An adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of a battery element and a packaging material for sealing the battery element.
The adhesive film for metal terminals is composed of a laminate including at least one polypropylene layer and at least one acid-modified polypropylene layer.
The acid-modified polypropylene layer constitutes a surface layer on at least one side of the adhesive film for metal terminals.
When the cross section of the polypropylene layer was observed by electron micrograph, the sea-island structure was observed.
An adhesive film for metal terminals in which the total thickness of the polypropylene layer is in the range of 0.7 or more and 3.5 or less when the total thickness of the acid-modified polypropylene layer is 1.
Item 2. Item 2. The adhesive film for metal terminals according to Item 1, wherein the polypropylene layer contains block polypropylene.
Item 3. Item 2. The adhesive film for metal terminals according to Item 1 or 2, wherein the polypropylene layer is made of unstretched polypropylene.
Item 4. Item 1 to 3, wherein the polypropylene layer has a laminated structure in which a layer made of random polypropylene, a layer made of block polypropylene, and a layer made of random polypropylene are laminated in this order. Adhesive film for metal terminals described in either.
Item 5. Item 2. The adhesive film for metal terminals according to any one of Items 1 to 4, wherein a melting peak is observed in the range of 150 ° C. or higher and 165 ° C. or lower when the adhesive film for metal terminals is measured by a differential scanning calorimeter. ..
Item 6. Item 2. The adhesive film for metal terminals according to any one of Items 1 to 5, wherein the adhesive film for metal terminals has a residual thickness of 50% or more, which is measured by the following measuring method.
An aluminum plate having a thickness of 100 μm and an adhesive film for the metal terminal are prepared.
The thickness A (μm) of the adhesive film for metal terminals is measured.
The adhesive film for metal terminals is laminated on the central portion of the aluminum plate so that the length direction and the width direction of the aluminum plate and the adhesive film for metal terminals coincide with each other.
Prepare two metal plates longer than the length of the aluminum plate and having a width of 7 mm so as to cover the entire surface of the adhesive film for metal terminals, and heat the temperature from above and below the aluminum plate and the adhesive film for metal terminals. The metal plate is heated and pressurized under the conditions of 190 ° C., a surface pressure of 1.27 MPa, and a time of 3 seconds to obtain a laminate of the aluminum plate and the adhesive film for metal terminals.
The thickness B (μm) of the heated and pressurized portion of the laminate is measured.
The thickness residual ratio of the adhesive film for metal terminals is calculated by the following formula.
Thickness residual ratio (%) = (thickness B-100) / thickness A × 100 of adhesive film for metal terminals
Item 7. Item 2. The adhesive film for metal terminals according to any one of Items 1 to 6, wherein the adhesive film for metal terminals has a heat shrinkage rate of 70 to 90% in the flow direction.
Item 8. The packaging material is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order.
Item 2. The adhesive film for metal terminals according to any one of Items 1 to 7, wherein the adhesive film for metal terminals is interposed between the heat-sealing resin layer and the metal terminals.
Item 9. At least, a battery element having a positive electrode, a negative electrode, and an electrolyte, a packaging material for encapsulating the battery element, and a metal terminal electrically connected to each of the positive electrode and the negative electrode and projecting to the outside of the packaging material. It is a battery equipped with
A battery, wherein the adhesive film for metal terminals according to any one of Items 1 to 8 is interposed between the metal terminals and the packaging material.
Item 10. The use of a laminate comprising at least one polypropylene layer and at least one acid-modified polypropylene layer.
The acid-modified polypropylene layer constitutes a surface layer on at least one side of the adhesive film for metal terminals.
When the cross section of the polypropylene layer was observed by electron micrograph, the sea-island structure was observed.
When the total thickness of the acid-modified polypropylene layer is 1, the total thickness of the polypropylene layer is in the range of 0.7 or more and 3.5 or less.
Use of the laminate as an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of the battery element and a packaging material for encapsulating the battery element.

According to the present invention, it is possible to provide an adhesive film for a metal terminal having high adhesion to a packaging material and a metal terminal and also having excellent electrolytic solution resistance. Further, according to the present invention, it is also possible to provide a battery using the adhesive film for metal terminals.

It is a schematic plan view of the battery of this invention. FIG. 3 is a schematic cross-sectional view taken along the line AA'in FIG. FIG. 3 is a schematic cross-sectional view taken along the line BB'in FIG. 1. It is a schematic sectional drawing of the adhesive film for a metal terminal of this invention. It is a schematic sectional drawing of the adhesive film for a metal terminal of this invention. It is a schematic sectional drawing of the packaging material used for the battery of this invention. It is a schematic diagram for demonstrating the measuring method of the seal strength in an Example. It is a schematic diagram for demonstrating the measuring method of the seal strength in an Example. It is a schematic diagram for demonstrating the measuring method of the seal strength in an Example. It is a schematic diagram for demonstrating the measuring method of the seal strength in an Example. "Polymer microphotograph collection: Polymer seen by eye 1. Shape and function of molecular assembly" (Editor: Polymer Society, Publisher: Yamamoto, Publisher: Koufukan Co., Ltd., May 30, 1986, first edition It is a transmission type electron micrograph (scale bar is 5 μm) shown as “C” on page 29 of (Published).

The adhesive film for metal terminals of the present invention is an adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of a battery element and a packaging material for encapsulating the battery element. The adhesive film for metal terminals is composed of a laminate including at least one polypropylene layer and at least one acid-modified polypropylene layer, and the acid-modified polypropylene layer has adhesiveness for metal terminals. It constitutes the surface layer on at least one side of the film, and the polypropylene layer has a sea-island structure when the cross section is observed by an electron micrograph, and polypropylene is obtained when the total thickness of the acid-modified polypropylene layer is 1. The total thickness of the layers is in the range of 0.7 or more and 3.5 or less. Hereinafter, the adhesive film for metal terminals of the present invention and the battery of the present invention using the adhesive film will be described in detail.

In this specification, the numerical range indicated by "-" means "greater than or equal to" and "less than or equal to". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

1. 1. Adhesive film for metal terminals The adhesive film for metal terminals of the present invention is interposed between a metal terminal electrically connected to an electrode of a battery element and a packaging material for sealing the battery element. .. Specifically, for example, as shown in FIGS. 1 to 3, the adhesive film 1 for a metal terminal of the present invention comprises a metal terminal 2 electrically connected to an electrode of the battery element 4 and a battery element 4. It is interposed between the packaging material 3 to be sealed. Further, the metal terminal 2 projects to the outside of the packaging material 3 and is sandwiched between the packaging material 3 and the peripheral portion 3a of the heat-sealed packaging material 3 via the adhesive film 1 for the metal terminal. In the present invention, the heat when heat-sealing the packaging material is usually in the range of about 160 to 220 ° C., and the pressure is usually in the range of about 0.5 to 2.0 MPa.

The adhesive film 1 for metal terminals of the present invention is provided to improve the adhesion between the metal terminals 2 and the packaging material 3. By enhancing the adhesion between the metal terminal 2 and the packaging material 3, the sealing performance of the battery element 4 is improved. As described above, when the battery element 4 is heat-sealed, the battery element is sealed so that the metal terminal 2 electrically connected to the electrode of the battery element 4 projects to the outside of the packaging material 3. .. At this time, the metal terminal 2 formed of metal and the heat-sealing resin layer 34 (layer formed of heat-sealing resin such as polyolefin) located in the innermost layer of the packaging material 3 are formed of different materials. Therefore, when the adhesive film is not used, the sealing property of the battery element tends to be low at the interface between the metal terminal 2 and the heat-sealing resin layer 34. Further, even when an adhesive film is used, if the electrolytic solution resistance of the adhesive film is low, the sealing property of the battery element tends to be low.

For example, as shown in FIGS. 4 and 5, the adhesive film 1 for metal terminals of the present invention is composed of a laminate including at least one polypropylene layer 11 and at least one acid-modified polypropylene layer 12. The acid-modified polypropylene layer 12 constitutes the surface layer on at least one side of the adhesive film 1 for metal terminals, and the polypropylene layer 11 has a sea-island structure observed when the cross section is observed by an electron micrograph, and further. When the total thickness of the acid-modified polypropylene layer 12 is 1, the total thickness of the polypropylene layer 11 is set in the range of 0.7 to 3.5. As a result, the adhesive film 1 for metal terminals of the present invention has high adhesion to the packaging material and the metal terminals, and is also excellent in electrolytic solution resistance, so that the sealing property of the battery element is effectively enhanced. be able to.

As the total thickness of the polypropylene layer 11 when the total thickness of the acid-modified polypropylene layer 12 is 1, from the viewpoint of further improving the electrolytic solution resistance while further improving the adhesion to the packaging material and the metal terminal. Is preferably in the range of about 0.75 to 3.2, and more preferably in the range of about 0.8 to 2.0.

In the adhesive film 1 for metal terminals of the present invention, the acid-modified polypropylene layer 12 constitutes the surface layer on at least one side of the adhesive film for metal terminals. The acid-modified polypropylene layer 12 made of acid-modified polypropylene is superior in adhesion to a metal material as compared with the polypropylene layer 11 made of polypropylene. Therefore, by arranging the adhesive film 1 for metal terminals of the present invention between the metal terminals 2 and the packaging material 3 so that the acid-modified polypropylene layer 12 is located on the metal terminal 2 side, the battery element The sealing property can be effectively improved.

The adhesive film 1 for metal terminals of the present invention may be provided with at least one polypropylene layer 11 and one acid-modified polypropylene layer 12. As a preferable laminated structure of the adhesive film 1 for metal terminals of the present invention, for example, as shown in FIG. 4, a structure in which the polypropylene layer 11 and the acid-modified polypropylene layer 12 are laminated one by one, or, for example, FIG. 5 shows. As shown, the configuration in which the acid-modified polypropylene layer 12 is laminated one by one on both surfaces of the polypropylene layer 11 and the like can be mentioned. As will be described later, even if a plurality of layers made of the same or different polypropylenes are continuously laminated on the one-layer polypropylene layer 11, the plurality of layers constitute the one-layer polypropylene layer 11. good. Similarly, a plurality of layers made of the same or different acid-modified polypropylene are continuously laminated on the acid-modified polypropylene layer 12 of one layer, and the plurality of layers constitute the acid-modified polypropylene layer 12 of one layer. May be.

As a specific example of a preferable laminated structure of the adhesive film 1 for metal terminals of the present invention, a two-layer structure of an acid-modified polypropylene layer 12 / polypropylene layer 11; an acid-modified polypropylene layer 12 / polypropylene layer 11 / acid-modified polypropylene layer 12 A three-layer structure in which the acid-modified polypropylene layer 12 / polypropylene layer 11 / acid-modified polypropylene layer 12 / polypropylene layer 11 / acid-modified polypropylene layer 12 are laminated in this order can be mentioned. Above all, a two-layer structure of the acid-modified polypropylene layer 12 / polypropylene layer 11; a three-layer structure in which the acid-modified polypropylene layer 12 / polypropylene layer 11 / acid-modified polypropylene layer 12 are laminated in this order is more preferable.

In the adhesive film 1 for metal terminals of the present invention, it is preferable that all layers are made of polyolefin. More specifically, the adhesive film 1 for metal terminals of the present invention preferably has an embodiment composed of only the acid-modified polypropylene layer 12 and the polypropylene layer 11, and further includes another polyolefin layer composed of polyolefin. The above aspect is also preferable. Specific examples of the polyolefin constituting the polyolefin layer include polyethylene and acid-modified polyethylene. In the acid-modified polyethylene, the component that acid-denatures ethylene is not particularly limited, and examples thereof include unsaturated carboxylic acids or anhydrides thereof used for acid modification exemplified in the acid-modified polypropylene layer 12 described later.

The thickness of the adhesive film 1 for metal terminals of the present invention is not particularly limited, but is preferably 40 from the viewpoint of further improving the adhesion to the packaging material and the metal terminals and further improving the electrolytic solution resistance. It is about 200 μm, more preferably about 55 to 150 μm, still more preferably about 60 to 110 μm.

Further, from the viewpoint of further improving the electrolytic solution resistance while further improving the adhesion to the packaging material and the metal terminal, the adhesive film 1 for the metal terminal of the present invention is measured by a differential scanning calorimeter. It is preferable that a melting peak is observed in the range of 150 to 165 ° C.

From the same viewpoint, the adhesive film 1 for metal terminals of the present invention preferably has a residual thickness of about 50% or more of the adhesive film for metal terminals measured by the following measuring method. It is preferably about 55% or more, and preferably about 60% or more. The upper limit of the thickness residual ratio is preferably about 90% or less, preferably about 85% or less, and preferably about 80% or less. The range of the thickness residual ratio is preferably about 55 to 90%, about 55 to 85%, about 55 to 80%, about 60 to 90%, about 60 to 85%, and about 60 to 80%. Will be. By using the adhesive film 1 for metal terminals having a residual ratio of 50% or more, it is possible to effectively suppress a short circuit between the barrier layer and the metal terminal contained in the packaging material, and the packaging material and the metal. It is possible to further improve the adhesion with the adhesive film for terminals. Further, by using the adhesive film 1 for metal terminals having the residual ratio of 90% or less, the shape of the step of the metal terminal can be suitably followed, and the end portion of the metal terminal can be suitably covered. Can be done.

(Measurement of residual thickness of adhesive film for metal terminals)
Prepare an aluminum plate (pure aluminum type, JIS H4160-1994 A1N30HO) with a thickness of 100 μm and an adhesive film for metal terminals. The thickness A (μm) of the adhesive film for metal terminals is measured with a microgauge. The adhesive film for metal terminals is laminated on the central portion of the aluminum plate so that the length direction and the width direction of the aluminum plate and the adhesive film for metal terminals match. At this time, the acid-modified polypropylene layer of the adhesive film for metal terminals is arranged so as to be in contact with the aluminum plate. Prepare two metal plates that are longer than the length of the aluminum plate and have a width of 7 mm, and cover the entire surface of the adhesive film for metal terminals. Heating and pressurization are performed under the conditions of a pressure of 1.27 MPa and a time of 3 seconds to obtain a laminate of an aluminum plate and an adhesive film for metal terminals. The thickness B (μm) of the heated and pressurized portion of the laminate is measured with a microgauge. The thickness residual ratio of the adhesive film for metal terminals is calculated by the following formula.
Thickness residual ratio (%) = (thickness B-100) / thickness A × 100 of adhesive film for metal terminals
The length direction is the longitudinal direction corresponding to the long side in the plan view of the object, and the width direction is the short direction corresponding to the short side in the plan view of the object. When the sizes in the length direction and the width direction match (square), either of them may be the length direction and the width direction.

In measuring the residual ratio, depending on the area of the adhesive film for metal terminals, a pressure load may be applied so that the surface pressure becomes 1.27 MPa. Specifically, it can be converted by the formula [pressurized load (N) by metal plate] / [area (mm ² ) for pressurizing the adhesive film for metal terminals] = surface pressure (MPa). The pressure load (N) by the metal plate can be adjusted by the diameter of the cylinder for adjusting the pressure of the metal plate and the air pressure.

In the above-mentioned measurement of the residual thickness of the adhesive film for metal terminals, if the measurement is performed under the conditions of a temperature of 190 ° C., a surface pressure of 1.27 MPa, and a time of 3 seconds, the lengths of the adhesive film for metal terminals and the aluminum plate are measured. And the width is not limited, but for example, when it is possible to measure with an adhesive film for metal terminals having a length of 70 mm and a width of 5 mm (a method such as cutting may be adopted), the adhesiveness for metal terminals of this size is acceptable. Using a film and an aluminum plate having a length of 60 mm and a width of 25 mm, the residual thickness of the adhesive film for metal terminals can be suitably measured. The [area for pressurizing the adhesive film for metal terminals (mm ² )] is the area of the portion where the aluminum plate and the adhesive film for metal terminals overlap, for example, the adhesiveness for metal terminals of these sizes. When a film and an aluminum plate are used, the area is 60 mm × 5 mm. Further, the thickness of the aluminum plate does not substantially change due to heating and pressurization when obtaining a laminate of the aluminum plate and the adhesive film for metal terminals. Even if the size of the adhesive film for metal terminals to be measured is different, the size of the aluminum plate does not need to be changed if the above measurement can be performed.

The melt mass flow rate (MFR) of the entire adhesive film 1 for metal terminals of the present invention is not particularly limited, but is a viewpoint of further improving the electrolytic solution resistance while further improving the adhesion to the packaging material and the metal terminals. From the above, preferably about 1 to 15, more preferably about 2 to 12, and even more preferably about 3 to 10. The melt mass flow rate (MFR) of the entire adhesive film 1 for metal terminals is a value measured using a melt indexer at a measurement temperature of 230 ° C. and a weight of 2.16 kg by a method in accordance with JIS K7210: 2014. Is.

Further, the lower limit of the heat shrinkage rate (%) in the flow direction (MD) of the adhesive film 1 for metal terminals of the present invention is preferably about 70% or more, more preferably about 75% or more, still more preferably about. 80% or more is mentioned, and the upper limit is preferably about 95% or less, more preferably about 92% or less, still more preferably about 90% or less. The range of the heat shrinkage rate (%) is preferably about 70 to 95%, about 70 to 92%, about 70 to 90%, about 75 to 95%, about 75 to 92%, and about 75 to 90. %, 80-95%, 80-92%, 80-90%. The method for measuring the heat shrinkage rate (%) is as follows.

(Measurement method of heat shrinkage rate (%))
An adhesive film for metal terminals is cut into a size of 50 mm (MD) x 4 mm (TD) in length and used as a test piece. Next, the length M (mm) of the test piece is measured with a metal scale. Next, the end portion of the test piece in the length direction is fixed to the wire mesh with tape so that the test piece is suspended from the wire mesh. In this state, the test piece is placed in an oven heated to 190 ° C. for 120 seconds, and then the test piece is taken out together with the wire mesh and naturally cooled in a room temperature (25 ° C.) environment. Next, the length N (mm) of the test piece naturally cooled to room temperature is measured with a metal scale. The heat shrinkage of the adhesive film for metal terminals is calculated by the following formula.
Heat shrinkage rate (%) = (length N / length M) x 100

When the adhesive film for metal terminals is heat-sealed while being sandwiched between the metal terminals and the packaging material at the time of sealing the battery element, the pressure from the metal plate used for heat sealing causes the adhesive film to be heat-sealed. There is a portion where the adhesive film for metal terminals does not change in size and a portion where pressure is not applied due to the distance from the metal plate and the film shrinks. At this time, it is possible to effectively prevent the thickness of the portion to which the pressure is applied from becoming too thin by appropriately heat-shrinking the portion to which the pressure is applied toward the portion to which the pressure is applied. On the other hand, if the heat shrinkage of the adhesive film for metal terminals is too large, the adhesive film 1 for metal terminals is installed on the metal terminals, and the adhesive film for metal terminals is adhered in the preheating stage before being subjected to heat sealing. The sex film moves due to heat shrinkage, and there is a possibility that the positional relationship between the metal terminal and the adhesive film for the metal terminal may be displaced. Therefore, it is desirable that the adhesive film 1 for metal terminals of the present invention has an appropriate heat shrinkage rate. As an appropriate heat shrinkage rate of the adhesive film 1 for metal terminals of the present invention, for example, the lower limit of the heat shrinkage rate (%) in the flow direction (MD) described above is 70% or more. Be done.

(Polypropylene layer 11)
In the present invention, the polypropylene layer 11 is a layer made of polypropylene. Further, the polypropylene layer 11 has a sea-island structure when the cross section is observed by an electron micrograph. The observation of the sea island structure in the cross section of the polypropylene layer 11 means that the sea portion and the island portion are observed, for example, as shown in the electron micrograph shown in FIG. Fig. 11 shows "Polymer seen in a macromolecule microphotobook 1. Shape and function of molecular assembly" (Editor: Polymer Society of Japan, Publisher: Yamamoto, Publisher: Bunkakan Co., Ltd., 5 1986 It is a transmission electron micrograph (scale bar is 5 μm) shown as “C” on page 29 of the first edition issued on the 30th of March. The sea-island structure on the cross section of the polypropylene layer 11 can be confirmed by staining the cross section of the polypropylene layer with osmium tetroxide (OsO ₄ ) and observing an electron micrograph as shown in FIG. Although the sea portion is brighter than the island portion in FIG. 11, the sea portion may appear darker than the island portion depending on the measurement method and conditions. In any case, if the sea part and the island part can be discriminated, the ratio of the area of the island part in the sea island structure can be measured.

In the sea-island structure of the polypropylene layer 11, the ratio of the area of the island portion is not particularly limited, but from the viewpoint of further improving the adhesion to the packaging material and the metal terminal and further improving the electrolytic solution resistance. It is preferably about 10 to 50%, more preferably about 20 to 40%. The method for measuring the ratio of the area of the island portion in the sea island structure of the polypropylene layer 11 is as follows. If the ratio of the area of the island is 2% or less, it is evaluated that the island does not have a substantially sea-island structure.

(Measuring method of the ratio of the area of the island part in the sea island structure)
An adhesive film for metal terminals is embedded in a thermosetting epoxy resin and cured. A commercially available rotary microtome (UC6 manufactured by LEICA) and a cross section in the desired direction (cross section along the TD) are prepared using a diamond knife, and at that time, a cryomicrotome using liquid nitrogen is used to make -70. Make a cross section at ° C. Stain the embedding resin with ruthenium tetroxide overnight. Since polypropylene expands when dyed, the expanded portion is trimmed with a microtome, and the portion further cut by about 1 to 2 μm with a thickness of about 100 nm is observed as follows. The stained cross section is observed with a field emission scanning electron microscope (for example, S-4800 TYPE1 manufactured by Hitachi High-Technologies Corporation, measurement conditions: 3 kV 20 mA High WD 6 mm detector (Upper)), and an image (magnification is 10000 times) is obtained. get. Next, using image processing software that can binarize the image (for example, image analysis software WinROOF (Ver7.4) manufactured by Mitani Shoji, the island part and the sea part of the sea island structure are binarized for the image. , The ratio of the area occupied by the island portion (total area of the island portion / area of the measurement range of the image) is obtained. For specific image processing conditions, for example, the conditions described in Examples are adopted.

By observing the sea-island structure when observing the cross section of the polypropylene layer 11 with an electron micrograph, the cold resistance is enhanced while maintaining the excellent heat resistance of the adhesive film for metal terminals. In addition, the adhesion to the packaging material and the metal terminal is enhanced, and the electrolytic solution resistance is also improved.

Further, in the present invention, the polypropylene layer 11 is preferably made of unstretched polypropylene. It can be confirmed by analyzing the polypropylene layer 11 by the X-ray diffraction method that the polypropylene layer 11 is made of unstretched polypropylene and is not made of stretched polypropylene. Specifically, when the wide-angle X-ray diffraction of the polypropylene layer 11 composed of unstretched polypropylene is measured, it corresponds to 110 planes of the polypropylene crystal with respect to the intensity of the peak corresponding to the 040 planes calculated from the diffraction pattern of the polypropylene crystal. The ratio of peak intensities (peak intensity of 040 planes / peak strength of 110 planes) is in the range of 0.5 to 1.5, and the polypropylene layer made of stretched polypropylene is out of this range. That is, in the present invention, when wide-angle X-ray diffraction is measured, the polypropylene layer 11 has the ratio of the intensity of the peak corresponding to 110 planes of the polypropylene crystal to the intensity of the peak corresponding to 040 planes calculated from the diffraction pattern of the polypropylene crystal ( It is composed of polypropylene having a peak intensity of 040 planes / peak strength of 110 planes) in the range of 0.5 to 1.5.

The peak corresponding to the 110th plane appears in the vicinity of 2θ = 14 °, and the peak corresponding to the 040 plane appears in the vicinity of 2θ = 17 °. The measurement conditions by wide-angle X-ray diffraction are Ruler / PCS (opening angle of incident parallel slit): 5.0 deg, IS length (length of longitudinal limiting slit): 10.0 mm, PSA open (opening angle of light receiving PSA is open). ), Ruler (opening angle of the light receiving parallel slit): 5.0 deg, 2θ / θ: 2 to 40 deg, and the step is 0.04 deg.

Further, it can be confirmed by analyzing the polypropylene layer 11 by Raman spectroscopy that the polypropylene layer 11 is made of unstretched polypropylene and is not made of stretched polypropylene. Specifically, when the polypropylene layer is analyzed by Raman spectroscopy, the high crystalline peak intensity "A" appearing at about 809 cm ^-1 and the high amorphous peak intensity appearing at about 842 cm ^-1 . When the ratio (A / B) of "B" is 1.6 or less, it can be confirmed that the polypropylene layer 11 is composed of unstretched polypropylene. The measurement conditions were a laser wavelength of 633 nm, a grating of 600 gr / mm, a confocal hole of 100 μm, a microscope lens of 10 times, an exposure time of 15 sec, and an integration number of once. The Raman spectrum was measured so that the MD and the incident laser polarization plane were parallel to each other. The straight line connecting 710 cm ^-1 and 925 cm ^-1 was used as the baseline. As the analysis condition, the peak heights at 809 cm ^-1 and 842 cm ^-1 at the time of baseline correction were calculated as the peak intensities. The high crystalline peak intensity “A” appearing at about 809 cm ^-1 described above is a peak attributed to the combination mode of main chain CC expansion and contraction and CH3 variable angular vibration. Further, the height "B" of the amorphous peak intensity appearing at about 842 cm ^-1 is a peak attributed to the CH3 variable angular vibration mode.

In the present invention, the method for confirming the MD of the polypropylene layer 11 is as follows. For each cross section (total of 10 cross sections) of the polypropylene layer 11 in the length direction and the cross section in the direction perpendicular to the cross section in the length direction by changing the angle by 10 degrees from the direction parallel to the cross section in the length direction. , Each of them is observed by electron micrograph to confirm the structure of the sea island. Next, in each cross section, the shape of each island is observed. For the shape of each island, the diameter y is the linear distance connecting the leftmost end in the direction perpendicular to the thickness direction of the polypropylene layer 11 and the rightmost end in the vertical direction. In each cross section, the average of the top 20 diameters y is calculated in descending order of the diameter y of the island shape. The direction parallel to the cross section in which the average of the diameter y of the island shape is the largest is determined to be MD.

The polypropylene contained in the polypropylene layer 11 is preferably crystalline such as homopolypropylene, a block copolymer of polypropylene (for example, a block copolymer of propylene and ethylene), a random copolymer of polypropylene (for example, a random copolymer of propylene and ethylene), or the like. Examples include amorphous polypropylene. Examples of the composition in which the polypropylene layer 11 has the above-mentioned sea-island structure include a composition in which the polypropylene layer 11 contains a block copolymer of polypropylene, a composition containing a block copolymer of polypropylene and a random copolymer of polypropylene, and homopolypropylene and random polypropylene. Examples thereof include a composition containing a polyethylene component. Among these, the polypropylene layer 11 more preferably contains block polypropylene, and further preferably is made of block polypropylene. The proportion of propylene contained in the block polypropylene is preferably about 10 to 90% by mass, more preferably about 30 to 80% by mass.

In the adhesive film 1 for metal terminals of the present invention, the polypropylene layer 11 may be only one layer or may be two or more layers. Further, a plurality of layers made of the same or different polypropylenes may be continuously laminated on the polypropylene layer 11 of one layer, and the plurality of layers may form the polypropylene layer 11 of one layer. The polypropylene layer 11 preferably includes a layer made of block polypropylene.

A preferred embodiment of the one-layer polypropylene layer 11 is a laminate of a layer made of random polypropylene and a layer made of block polypropylene, and in particular, a layer made of random polypropylene and block polypropylene. It is preferable to have a laminated structure (three-layer structure) in which a layer composed of the above and a layer composed of random polypropylene are laminated in this order.

In the present invention, when a plurality of layers made of polypropylene are continuously laminated, these layers are collectively referred to as one polypropylene layer 11. Similarly, when a plurality of layers composed of acid-modified polypropylene are continuously laminated, these layers are collectively referred to as one acid-modified polypropylene layer 12.

The thickness of the polypropylene layer 11 of one layer is not particularly limited as long as the total thickness of the polypropylene layer 11 is in the range of 0.7 to 3.5 when the total thickness of the acid-modified polypropylene layer 12 is 1. However, from the viewpoint of further improving the adhesion to the packaging material and the metal terminal and further improving the electrolytic solution resistance, it is preferably about 15 to 80 μm, more preferably about 20 to 70 μm. Although the details of the mechanism are not clear, if the thickness of the acid-modified polypropylene layer is too large, the acid-modified polypropylene layer tends to be aggregated and broken, and the adhesiveness of the adhesive film for metal terminals tends to decrease. It is in.

From the viewpoint of further improving the electrolytic solution resistance while further improving the adhesion to the packaging material and the metal terminal, the polypropylene layer 11 is the thickness of the adhesive film 1 for the metal terminal in the adhesive film 1 for the metal terminal. It preferably occupies about 40% or more, more preferably about 45% or more, and as an upper limit, the polypropylene layer 11 preferably occupies about 85% or less of the thickness of the adhesive film 1 for metal terminals. It is more preferable to occupy 80% or less. The preferable range of the thickness of the polypropylene layer 11 in the thickness of the adhesive film 1 for metal terminals is about 40 to 85% and about 45 to 80%.

The melting peak temperature of the polypropylene layer 11 is not particularly limited, but is preferably about 140 to 165 ° C. from the viewpoint of further improving the electrolytic solution resistance while further improving the adhesion to the packaging material and the metal terminal. More preferably, it is about 150 to 160 ° C. In the present invention, the melting peak temperature of the polypropylene layer 11 is a value measured by using a differential scanning calorimeter (DSC), the temperature rise rate is 10 ° C./min, and the temperature measurement range is −50 to 200 ° C. , Measured using an aluminum pan as a sample pan.

(Acid-modified polypropylene layer 12)
In the present invention, the acid-modified polypropylene layer 12 is a layer made of acid-modified polypropylene. It is preferable that the sea-island structure of the acid-modified polypropylene layer 12 is also observed when the cross section is observed by electron micrograph. The method for confirming the sea-island structure in the acid-modified polypropylene layer 12 is the same as the confirmation method for the polypropylene layer 11 described above.

In the sea-island structure of the acid-modified polypropylene layer 12, the ratio of the area of the island portion is not particularly limited, but from the viewpoint of further improving the adhesion to the packaging material and the metal terminal and further improving the electrolytic solution resistance. Is preferably about 10 to 50%, more preferably about 20 to 40%. The method for measuring the ratio of the area of the island portion in the sea-island structure of the acid-modified polypropylene layer 12 is the same as the measurement method for the polypropylene layer 11 described above, except that the measurement target is the acid-modified polypropylene layer 12. If the ratio of the area of the island is 2% or less, it is evaluated that the island does not have a substantially sea-island structure.

The acid-modified polypropylene is not particularly limited as long as it is an acid-modified polypropylene, but preferably includes an unsaturated carboxylic acid or a polypropylene graft-modified with an anhydride thereof. Examples of the unsaturated carboxylic acid or its anhydride used for acid modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

The acid-modified polypropylene is preferably crystalline or amorphous, such as homopolypropylene, a block copolymer of polypropylene (eg, a block copolymer of propylene and ethylene), a random copolymer of polypropylene (eg, a random copolymer of propylene and ethylene). Sexual polypropylene can be mentioned. Among these, it is preferable to include a block copolymer of polypropylene (block polypropylene) or a random copolymer of polypropylene (random polypropylene). The fact that the acid-modified polypropylene layer 12 is a layer made of acid-modified polypropylene can be analyzed by infrared spectroscopy, gas chromatography mass analysis, or the like, and the analysis method is not particularly limited. For example, when maleic anhydride-modified polypropylene is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected in the vicinity of wave number 1760 cm ^-1 and wave number 1780 cm ^-1 . However, if the degree of acid denaturation is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

In the adhesive film 1 for metal terminals of the present invention, the acid-modified polypropylene layer 12 may have only one layer or two or more layers. Further, a plurality of layers made of the same or different acid-modified polypropylene are continuously laminated on the acid-modified polypropylene layer 12 of one layer, and the plurality of layers constitute the acid-modified polypropylene layer 12 of one layer. May be.

A preferred embodiment of the single acid-modified polypropylene layer 12 is a layer made of maleic anhydride-modified polypropylene.

The thickness of the acid-modified polypropylene layer 12 of one layer is particularly high if the total thickness of the polypropylene layer 11 is in the range of 0.7 to 3.5 when the total thickness of the acid-modified polypropylene layer 12 is 1. Although not limited, from the viewpoint of further improving the adhesion to the packaging material and the metal terminal and further improving the electrolytic solution resistance, preferably about 10 μm or more, still more preferably about 15 μm or more, and the upper limit is set. It is preferably about 40 μm or less, more preferably about 35 μm or less, still more preferably about 30 μm or less.

The melting peak temperature of the acid-modified polypropylene layer 12 is not particularly limited, but is preferably 130 to 165 ° C. from the viewpoint of further improving the adhesion to the packaging material and the metal terminal and further improving the electrolytic solution resistance. The degree, more preferably about 140 to 160 ° C. is mentioned. In the present invention, the melting peak temperature of the acid-modified polypropylene layer 12 is a value measured in the same manner as the method for measuring the melting peak temperature of the polypropylene layer 11.

From the viewpoint of improving the sealing strength while suppressing the crushing of the adhesive film for metal terminals during heat sealing, the softening point of the polypropylene layer 11 and the acid-modified polypropylene layer 12 in the adhesive film 1 for metal terminals of the present invention. As the absolute value of the difference in softening points, the upper limit is preferably about 40 ° C. or lower, more preferably about 30 ° C. or lower, still more preferably about 20 ° C. or lower, and the lower limit is preferably about 0 ° C. or higher. The temperature is preferably about 5 ° C. or higher, more preferably about 10 ° C. or higher. The softening points of the polypropylene layer 11 and the acid-modified polypropylene layer 12 are values measured as follows.

(Measuring method of softening point)
Using a scanning thermal microscope (NanoTA manufactured by Anasys), the cantilever model of the thermal probe is a value measured under the conditions of EX-AN2-200 and a heating rate of 5 ° C./s. The softening point was set to the peak top temperature.

The adhesive film 1 for metal terminals of the present invention may contain various additives such as a lubricant, an antioxidant, an ultraviolet absorber, and a light stabilizer, if necessary. The adhesive film 1 for metal terminals may be discolored depending on the type and content of the additive.

The content of the lubricant contained in the entire adhesive film 1 for metal terminals is preferably about 0 to 2000 ppm.

(Measurement of lubricant amount)
The content of the lubricant contained in the entire adhesive film 1 for metal terminals is a value measured using a gas chromatograph mass spectrometer (GC-MS). Specifically, the additive in the adhesive film for metal terminals is extracted into methanol in boiling and recirculated methanol, and the obtained methanol extract is analyzed by GC-MS to be used for metal terminals. The amount of lubricant contained in the entire adhesive film is measured.

The lubricant is not particularly limited, but an amide-based lubricant is preferable. Specific examples of the amide-based lubricant include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, and unsaturated fatty acid bisamides. Specific examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like. Specific examples of unsaturated fatty acid amides include oleic acid amides and erucic acid amides. Specific examples of the substituted amide include N-oleyl palmitate amide, N-stearyl stearyl amide, N-stearyl oleate amide, N-oleyl stealic acid amide, N-stearyl erucate amide and the like. Further, specific examples of trimethylolamide include trimethylolstearic acid amide. Specific examples of the saturated fatty acid bisamide include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbechenic acid amide, and hexamethylene bisstea. Examples thereof include acid amides, hexamethylene bisbechenic acid amides, hexamethylene hydroxystearic acid amides, N, N'-distealyl adipic acid amides, N, N'-distearyl sebasic acid amides and the like. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amides, ethylene biserukaic acid amides, hexamethylene bisoleic acid amides, N, N'-diorail adipic acid amides, and N, N'-diorail sevacinic acid amides. And so on. Specific examples of the fatty acid ester amide include stearoamide ethyl stearate and the like. Specific examples of the aromatic bisamide include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N, N'-distearylisophthalic acid amide. The lubricant may be used alone or in combination of two or more.

Further, the adhesive film 1 for metal terminals of the present invention may contain a filler, if necessary. Since the adhesive film 1 for the metal terminal contains the filler, the filler functions as a spacer, so that the short circuit between the metal terminal 2 and the barrier layer 33 of the packaging material 3 is more effectively performed. It becomes possible to suppress it. The particle size of the filler may be in the range of about 0.1 to 35 μm, preferably about 5.0 to 30 μm, and more preferably about 10 to 25 μm. When a filler is added to the adhesive film 1 for metal terminals, it is preferably contained in the polypropylene layer 11 and / or the acid-modified polypropylene layer 12, and the content of the filler is the polypropylene layer 11 and the acid-modified polypropylene. About 5 to 30 parts by mass, more preferably about 10 to 20 parts by mass, respectively, with respect to 100 parts by mass of the resin component forming the layer 12.

As the filler, either an inorganic type or an organic type can be used. Examples of the inorganic filler include carbon (carbon, graphite), silica, aluminum oxide, barium titanate, iron oxide, silicon carbide, zirconium oxide, zirconium silicate, magnesium oxide, titanium oxide, calcium aluminium, and calcium hydroxide. , Aluminum hydroxide, magnesium hydroxide, calcium carbonate and the like. Examples of the organic filler include fluororesin, phenol resin, urea resin, epoxy resin, acrylic resin, benzoguanamine / formaldehyde condensate, melamine / formaldehyde condensate, polymethylmethacrylate crosslinked product, polyethylene crosslinked product and the like. Can be mentioned. Aluminum oxide, silica, fluororesin, acrylic resin, and benzoguanamine / formaldehyde condensate are preferable from the viewpoint of shape stability, rigidity, and content resistance, and among these, spherical aluminum oxide and silica are more preferable. As a method of mixing the filler with the resin component forming the polypropylene layer 11 and / or the acid-modified polypropylene layer 12, a method of melt-blending both of them with a Banbury mixer or the like in advance and making a masterbatch into a predetermined mixing ratio. , A direct mixing method with a resin component or the like can be adopted.

Further, each of the adhesive films 1 for metal terminals may contain a pigment, if necessary. As the pigment, various inorganic pigments can be used. As a specific example of the pigment, carbon (carbon, graphite) exemplified in the above-mentioned filler can be preferably exemplified. Carbon (carbon, graphite) is a material generally used inside a battery, and there is no risk of elution with respect to the electrolytic solution. In addition, a sufficient coloring effect can be obtained with an addition amount such that the coloring effect is large and the adhesiveness is not impaired, and the added resin is not melted by heat, and the apparent melt viscosity of the added resin can be increased. Further, it is possible to prevent the pressurized portion from becoming thin during heat bonding (sealing) and prevent a decrease in sealing strength.

When a pigment is added to the adhesive film 1 for metal terminals, it is preferably contained in the polypropylene layer 11 and / or the acid-modified polypropylene layer 12, and the amount thereof is, for example, carbon black having a particle size of about 0.03 μm. When is used, about 0.05 to 0.3 parts by mass, preferably 0.1 to 0.2 parts by mass, respectively, with respect to 100 parts by mass of the resin component forming the polypropylene layer 11 and the acid-modified polypropylene layer 12. The degree is mentioned. By adding a pigment to the adhesive film 1 for metal terminals, the presence or absence of the adhesive film 1 for metal terminals can be detected by a sensor or visually inspected. When the filler and the pigment are added to the polypropylene layer 11 and / or the acid-modified polypropylene layer 12, the filler and the pigment may be added to the same polypropylene layer 11 and / or the acid-modified polypropylene layer 12. From the viewpoint of not impairing the heat fusion property of the adhesive film 1 for metal terminals, it is preferable to add the filler and the pigment separately to the polypropylene layer 11 and the acid-modified polypropylene layer 12.

The adhesive film 1 for metal terminals of the present invention can be produced by laminating at least one polypropylene layer and at least one acid-modified polypropylene layer. The method for laminating at least one polypropylene layer and at least one acid-modified polypropylene layer is not particularly limited, and for example, a thermal laminating method, a sandwich laminating method, an extruded laminating method, or the like can be used.

The method of interposing the adhesive film 1 for metal terminals between the metal terminals 2 and the packaging material 3 is not particularly limited, and for example, as shown in FIGS. 1 to 3, the metal terminals 2 are sandwiched by the packaging material 3. The metal terminal adhesive film 1 may be wound around the metal terminal 2 at the portion where the metal terminal is formed. Further, although not shown, in the portion where the metal terminal 2 is sandwiched by the packaging material 3, the adhesive film 1 for the metal terminal is arranged on both sides of the metal terminal 2 so as to cross the two metal terminals 2. You may.

[Metal terminal 2]
The adhesive film 1 for metal terminals of the present invention is used by interposing it between the metal terminals 2 and the packaging material 3. The metal terminal 2 (tab) is a member electrically connected to an electrode (positive electrode or negative electrode) of the battery element 4, and is made of a metal material. The metal material constituting the metal terminal 2 is not particularly limited, and examples thereof include aluminum, nickel, and copper. For example, the metal terminal 2 connected to the positive electrode of a lithium ion battery is usually made of aluminum or the like. Further, the metal terminal connected to the negative electrode of the lithium ion battery is usually made of copper, nickel or the like.

The surface of the metal terminal 2 is preferably subjected to chemical conversion treatment from the viewpoint of enhancing the electrolytic solution resistance. For example, when the metal terminal 2 is made of aluminum, specific examples of the chemical conversion treatment include known methods for forming an acid resistant film such as phosphate, chromate, fluoride, and triazinethiol compound. .. Among the methods for forming an acid-resistant film, a phosphoric acid chromate treatment using a method composed of a phenol resin, a chromium (III) fluoride compound, and phosphoric acid is preferable.

The size of the metal terminal 2 may be appropriately set according to the size of the battery used and the like. The thickness of the metal terminal 2 is preferably about 50 to 1000 μm, more preferably about 70 to 800 μm. The length of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm. The width of the metal terminal 2 is preferably about 1 to 200 mm, more preferably about 3 to 150 mm.

[Packaging material 3]
Examples of the packaging material 3 include those having a laminated structure composed of a laminated body having at least a base material layer 31, a barrier layer 33, and a heat-sealing resin layer 34 in this order. FIG. 6 shows, as an example of the cross-sectional structure of the packaging material 3, an embodiment in which a base material layer 31, an adhesive layer 32, a barrier layer 33, an adhesive layer 35, and a heat-sealing resin layer 34 are laminated in this order. .. The adhesive layer 32 is a layer provided as needed for the purpose of enhancing the adhesion between the base material layer 31 and the barrier layer 33. Further, the adhesive layer 35 is a layer provided as needed for the purpose of enhancing the adhesion between the barrier layer 33 and the heat-sealing resin layer 34.

In the packaging material 3, the base material layer 31 is on the outermost layer side, and the heat-sealing resin layer 34 is on the innermost layer. At the time of assembling the battery, the battery element 4 is sealed and the battery element 4 is sealed by heat-welding the heat-fused resin layers 34 located on the peripheral edge of the battery element 4 to each other. Although FIGS. 1 to 3 show the battery 10 when the embossed type packaging material 3 formed by embossing or the like is used, the packaging material 3 may be an unmolded pouch type. good. The pouch type includes a three-way seal, a four-way seal, a pillow type, and the like, but any type may be used.

[Base material layer 31]
In the packaging material 3, the base material layer 31 is a layer that functions as a base material of the packaging material and is a layer that forms the outermost layer.

The material forming the base material layer 31 is not particularly limited as long as it has an insulating property. Examples of the material forming the base material layer 31 include polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicon resin, phenol resin, polyetherimide, polyimide, and mixtures and copolymers thereof. And so on.

The thickness of the base material layer 31 is, for example, about 10 to 50 μm, preferably about 15 to 30 μm.

[Adhesive layer 32]
In the packaging material 3, the adhesive layer 32 is a layer that is appropriately arranged on the base material layer 31 in order to impart adhesion to the base material layer 31. That is, the adhesive layer 32 is provided between the base material layer 31 and the barrier layer 33 as needed.

The adhesive layer 32 is formed by an adhesive capable of adhering the base material layer 31 and the barrier layer 33. The adhesive used to form the adhesive layer 32 may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesive used for forming the adhesive layer 32 is not particularly limited, and may be any of a chemical reaction type, a solvent volatile type, a heat melting type, a thermal pressure type and the like.

The thickness of the adhesive layer 32 is, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[Barrier layer 33]
In the packaging material, the barrier layer 33 is a layer having a function of improving the strength of the packaging material for a battery and preventing water vapor, oxygen, light, etc. from entering the inside of the battery. Specific examples of the metal constituting the barrier layer 33 include aluminum, stainless steel, titanium, and the like, preferably aluminum. The barrier layer 33 can be formed of, for example, a metal foil, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, a film provided with these vapor deposition films, or the like, and is formed of a metal foil. Is preferable, and it is more preferable to form it with an aluminum alloy foil. From the viewpoint of preventing wrinkles and pinholes from being generated in the barrier layer 33 during the manufacture of the packaging material for batteries, the barrier layer may be, for example, annealed aluminum (JIS H4160: 1994 A8021HO, JIS H4160: It is more preferably formed from a soft aluminum alloy foil such as 1994 A8079H-O, JIS H4000: 2014 A8021P-O, JIS H4000: 2014 A8079P-O).

The thickness of the barrier layer 33 is not particularly limited as long as it functions as a barrier layer such as water vapor, but can be, for example, about 10 to 50 μm, preferably about 10 to 40 μm.

[Adhesive layer 35]
In the packaging material 3, the adhesive layer 35 is a layer provided between the barrier layer 33 and the heat-sealing resin layer 34, if necessary, in order to firmly bond the heat-sealing resin layer 34.

The adhesive layer 35 is formed by an adhesive capable of adhering the barrier layer 33 and the heat-sealing resin layer 34. The composition of the adhesive used for forming the adhesive layer is not particularly limited, and examples thereof include a resin composition containing an acid-modified polyolefin. As the acid-modified polyolefin, for example, the same ones described in the acid-modified polypropylene layer 12 can be exemplified. Further, polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene was acid-modified with an unsaturated carboxylic acid or an anhydride thereof (for example, those exemplified in the acid-modified polypropylene layer 12). Things can also be exemplified.

The thickness of the adhesive layer 35 is, for example, about 1 to 40 μm, preferably about 2 to 30 μm.

[Heat-fused resin layer 34]
In the packaging material 3, the heat-fused resin layer 34 corresponds to the innermost layer, and is a layer in which the heat-fused resin layers are heat-welded to each other at the time of assembling the battery to seal the battery element.

The resin component used in the heat-weldable resin layer 34 is not particularly limited as long as it can be heat-welded, and examples thereof include polyolefins and acid-modified polyolefins.

Examples of the polyolefin include the same ones exemplified in the polypropylene layer 11 and polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene. Moreover, as the acid-modified polyolefin, the same one as described in the adhesive layer 35 can be mentioned.

The thickness of the heat-sealing resin layer 34 is not particularly limited, but is preferably about 2 to 2000 μm, more preferably about 5 to 1000 μm, and even more preferably about 10 to 500 μm.

2. 2. Battery 10
The battery 10 of the present invention is electrically connected to at least a battery element 4 provided with a positive electrode, a negative electrode, and an electrolyte, a packaging material 3 for encapsulating the battery element 4, and a positive electrode and a negative electrode, respectively, and is a packaging material. It is provided with a metal terminal 2 projecting to the outside of 3. The battery 10 of the present invention is characterized in that the adhesive film 1 for metal terminals of the present invention is interposed between the metal terminal 2 and the packaging material 3.

Specifically, the metal of the present invention has a battery element 4 provided with at least a positive electrode, a negative electrode, and an electrolyte, in a state where the metal terminals 2 connected to each of the positive electrode and the negative electrode are projected outward in the packaging material 3. The terminal adhesive film 1 is interposed between the metal terminal 2 and the heat-sealing resin layer 34, and the flange portion of the packaging material (in the region where the heat-sealing resin layers 34 come into contact with each other) is placed on the peripheral edge of the battery element 4. The battery 10 using the packaging material 3 is provided by covering the peripheral portion 3a) of the packaging material so that it can be formed and heat-sealing the heat-sealing resin layers 34 of the flange portions to seal each other. To. When the battery element 4 is accommodated by using the packaging material 3, the heat-sealing resin layer 34 of the packaging material 3 is used so as to be inside (the surface in contact with the battery element 4).

The battery of the present invention may be either a primary battery or a secondary battery, but is preferably a secondary battery. The type of the secondary battery is not particularly limited, and for example, a lithium ion battery, a lithium ion polymer battery, a lead livestock battery, a nickel / hydrogen livestock battery, a nickel / cadmium livestock battery, a nickel / iron livestock battery, and a nickel / zinc livestock battery. Examples thereof include batteries, silver oxide / zinc livestock batteries, metal air batteries, polyvalent cation batteries, capacitors, capacitors and the like. Among these secondary batteries, a lithium ion battery and a lithium ion polymer battery are preferable.

When the thickness of the packaging material, the metal terminal, and the adhesive film for the metal terminal where the packaging material, the adhesive film for the metal terminal, and the metal terminal are laminated is measured, the packaging is packaged. The preferred thickness of the material is about 10 to 65 μm, the thickness of the metal terminal is about 50 to 1000 μm, and the preferred thickness of the adhesive film for metal terminals is about 30 to 80 μm. The total of the preferable thickness of the packaging material and the preferable thickness of the adhesive film for metal terminals is about 40 to 145 μm.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Evaluation of melting peak temperature measurement, heat shrinkage measurement, seal strength measurement, thickness residual rate measurement, electrolyte resistance and island portion area ratio measurement in sea island structure in Examples and Comparative Examples Was done as follows. The results of each are shown in Table 1.

(Measurement of melting peak temperature)
The adhesive film for metal terminals was measured using a differential scanning calorimeter (DSC). As an apparatus, "DSC-60 Plus" manufactured by Shimadzu Corporation was used. The measurement conditions were a temperature rise rate of 10 ° C./min, a temperature measurement range of −50 to 200 ° C., and an aluminum pan as a sample pan.

(Measurement of heat shrinkage)
The adhesive film for metal terminals was cut into a size of 50 mm (MD) × 4 mm (TD) in length and used as a test piece. Next, the length M (mm) of the test piece was measured with a metal scale. Next, the end portion of the test piece in the length direction was fixed to the wire mesh with tape, and the test piece was suspended from the wire mesh. In this state, the test piece was placed in an oven heated to 190 ° C. for 120 seconds, and then the test piece was taken out together with the wire mesh and naturally cooled in a room temperature (25 ° C.) environment. Next, the length N (mm) of the test piece naturally cooled to room temperature was measured with a metal scale. The heat shrinkage of the adhesive film for metal terminals was calculated by the following formula.
Heat shrinkage rate (%) = (length N / length M) x 100

(Measurement of seal strength)
As shown in the schematic diagram of FIG. 7, the packaging material 3 was cut into a size of 150 mm in length (MD) × 60 mm in width (TD). Further, the adhesive film 1 for metal terminals was cut into a size of 75 mm in length (MD) × 60 mm in width (TD). Further, a metal terminal 2 (aluminum plate, length 60 mm, width 25 mm, thickness 0.1 mm) was prepared. Next, as shown in the schematic diagram of FIG. 8, the packaging material 3 was folded in half in the length direction at the position of the center P of the MD so that the heat-sealing resin layer was on the inside. Next, the adhesive film 1 for metal terminals and the metal terminals 2 (aluminum plate, length 60 mm, width 25 mm, thickness 0.1 mm) are overlapped and folded in half as shown in the schematic diagram of FIG. Inserted between material 3. At this time, the acid-modified polypropylene layer of the adhesive film 1 for metal terminals was arranged so as to be in contact with the metal terminals 2. A cross-sectional view seen from the side is shown in FIG. 8b. In this state, as shown in the schematic diagram of FIG. 9a, heat sealing is performed from both sides of the packaging material 3 under the conditions of a sealing width of 7.0 mm, a sealing temperature of 190 ° C., a surface pressure of 1.0 MPa, and a sealing time of 3 seconds. A laminate was obtained. In the heat-sealed portion S of FIG. 9, the direction of the seal width corresponds to the MD of the packaging material. Next, a sample was cut out from the laminate at the position of the alternate long and short dash line in the schematic diagram of FIG. 9b so that the width of the heat-sealed portion S (TD of the packaging material) was 15 mm. The packaging material 3 of the obtained sample and the adhesive film 1 for metal terminals were separated from each other in the 180 ° direction to the position of the heat-sealed portion S. A cross-sectional view of the sample in this state as viewed from the side is shown in FIG. 9c. Next, using a tensile tester (AG-Xplus manufactured by Shimadzu Corporation), the seal strength (N / 15 mm) was measured under the conditions of a speed of 300 mm / min, a distance between chucks of 50 mm, and a T-shaped peeling method. .. At this time, as shown in FIG. 10, in the laminated body in which the packaging material 3 / the adhesive film for metal terminals 1 / the metal terminal 2 / the packaging material 3 are laminated in this order, "adhesive film for metal terminals 1 / metal terminal". 2 / Packaging material 3 ”is sandwiched between the lower chucks, and the packaging material 3 separated in the 180 ° direction is sandwiched between the upper chucks, and the packaging material 3 and the adhesive film 1 for metal terminals are peeled off. The seal strength was measured.

(Evaluation of electrolyte resistance)
The adhesive film for metal terminals was cut into a size of 15 mm (MD) × 100 mm (TD) and used as a test piece. Next, the test piece was immersed in an electrolytic solution (a solution of 1M LiPF ₆ (ethylene carbonate: dimethyl carbonate: diethyl carbonate = 1: 1: 1, volume ratio)) and stored in an oven at 85 ° C. for 24 hours. After taking out the test piece and washing it with water, the test piece was visually observed. The case where the layers of the test piece were not peeled off was defined as "A", and the case where the layers of the test piece were peeled off was "C". ".

(Measurement of residual thickness of adhesive film for metal terminals)
An aluminum plate (pure aluminum type, JIS H4160-1994 A1N30HO) having a length of 60 mm, a width of 25 mm, and a thickness of 100 μm and an adhesive film for the metal terminal having a length of 70 mm and a width of 5 mm were prepared. Next, the thickness A (μm) of the adhesive film for metal terminals was measured with a microgauge. Next, the adhesive film for metal terminals was laminated on the central portion of the aluminum plate so that the length direction and the width direction of the aluminum plate and the adhesive film for metal terminals coincided with each other. Next, prepare two metal plates that are longer than the length of the aluminum plate and have a width of 7 mm, and then cover the entire surface of the adhesive film for metal terminals so that the temperature can be increased from above and below the adhesive film for metal terminals. Heating and pressurization were performed under the conditions of 190 ° C., a surface pressure of 1.27 MPa, and a time of 3 seconds to obtain a laminate of an aluminum plate and an adhesive film for metal terminals. Next, the thickness B (μm) of the heated and pressurized portion of the laminate was measured with a microgauge. The thickness residual ratio of the adhesive film for metal terminals was calculated by the following formula. At this time, the thickness B is the center from one central portion of the laminated body and both end portions in the length direction of the laminated body (both ends of the portion where the aluminum plate and the adhesive film for metal terminals are laminated). The average value was taken from a total of 3 locations at 2 locations of 10 mm toward the portion.
Thickness residual ratio (%) = (thickness B-100) / thickness A × 100 of adhesive film for metal terminals

<Measurement method of the ratio of the area of the island part in the sea island structure>
An adhesive film for metal terminals was embedded in a thermosetting epoxy resin and cured. A commercially available rotary microtome (UC6 manufactured by LEICA) and a cross section in the desired direction (cross section along the TD) are prepared using a diamond knife, and at that time, a cryomicrotome using liquid nitrogen is used to make -70. A cross section was prepared at ° C. The entire resin was stained with ruthenium tetroxide overnight. Since polypropylene expands when dyed, the expanded portion is trimmed with a microtome, and a portion further cut by about 1 to 2 μm with a thickness of about 100 nm was observed as follows. The stained cross section is observed with a field emission scanning electron microscope (for example, Hitachi High-Technologies S-4800 TYPE1, measurement conditions: 3 kV 20 mA High WD 6 mm detector (Upper)), and an image (magnification is 10000 times) is obtained. Obtained. Next, using image processing software that can binarize the image (for example, image analysis software WinROOF (Ver7.4) manufactured by Mitani Shoji, the island part and the sea part of the sea island structure are binarized for the image. , The ratio of the area occupied by the island part (total area of the island part / area of the image measurement range) was obtained. The specific image processing conditions are as follows. In this measurement, the island Since the part was stained more than the sea part, the island part was observed brighter than the sea part.
[Image processing conditions]
3x3pix averaging binarization: automatic binarization Isolated point removal: Removes an object or background consisting of 1 pixel.
Delete: Delete particles by finding the shape feature value or density feature value (recognizing an area of 0.005 μm ² as noise)

<Manufacturing of adhesive film for metal terminals>
(Example 1)
As a polypropylene layer, an unstretched polypropylene film (CPP, total thickness 50 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (6 μm) / a block polypropylene layer (38 μm) / a random polypropylene layer (6 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on both sides of the unstretched polypropylene film by an extrusion laminating method, and an acid-modified polypropylene layer (25 μm) / polypropylene layer (50 μm) / acid-modified polypropylene layer (25 μm) were sequentially laminated. A laminated adhesive film for metal terminals was manufactured. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 83.0%.

(Example 2)
As a polypropylene layer, an unstretched polypropylene film (CPP, total thickness 60 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (8 μm) / a block polypropylene layer (44 μm) / a random polypropylene layer (8 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on both sides of the unstretched polypropylene film by an extrusion laminating method, and an acid-modified polypropylene layer (20 μm) / polypropylene layer (60 μm) / acid-modified polypropylene layer (20 μm) were sequentially laminated. A laminated adhesive film for metal terminals was manufactured. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 81.3%.

(Example 3)
As a polypropylene layer, an unstretched polypropylene film (CPP, total thickness 50 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (6 μm) / a block polypropylene layer (38 μm) / a random polypropylene layer (6 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on one side of the unstretched polypropylene film by an extrusion laminating method to produce an adhesive film for metal terminals in which an acid-modified polypropylene layer (16 μm) / polypropylene layer (50 μm) was laminated. bottom. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 80.1%.

(Example 4)
As the polypropylene layer, an unstretched polypropylene film (CPP, total thickness 30 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (4 μm) / a block polypropylene layer (22 μm) / a random polypropylene layer (4 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on one side of the unstretched polypropylene film by an extrusion laminating method to produce an adhesive film for metal terminals in which an acid-modified polypropylene layer (36 μm) / polypropylene layer (30 μm) was laminated. bottom. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 88.1%.

(Example 5)
As the polypropylene layer, an unstretched polypropylene film (CPP, total thickness 30 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (4 μm) / a block polypropylene layer (22 μm) / a random polypropylene layer (4 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on both sides of the unstretched polypropylene film by an extrusion laminating method, and an acid-modified polypropylene layer (18 μm) / polypropylene layer (30 μm) / acid-modified polypropylene layer (18 μm) were sequentially laminated. A laminated adhesive film for metal terminals was manufactured. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 88.1%.

(Example 6)
As the polypropylene layer, an unstretched polypropylene film (CPP, total thickness 60 μm, melting peak temperature 159 ° C.) of a block polypropylene layer (60 μm) was prepared. Next, maleic anhydride-modified polypropylene was laminated on both sides of the unstretched polypropylene film by an extrusion laminating method, and an acid-modified polypropylene layer (20 μm) / polypropylene layer (60 μm) / acid-modified polypropylene layer (20 μm) were sequentially laminated. A laminated adhesive film for metal terminals was manufactured. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 81.7%.

(Example 7)
As the polypropylene layer, an unstretched polypropylene film (CPP, total thickness 30 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (4 μm) / a block polypropylene layer (22 μm) / a random polypropylene layer (4 μm) are laminated in this order. ℃) was prepared. Next, an acid-modified polypropylene layer (16 μm) / polypropylene layer (30 μm) / acid-modified polypropylene (16 μm) was laminated on both sides of the unstretched polypropylene film by extruding and laminating maleic anhydride-modified polypropylene by an extrusion laminating method. Manufactured adhesive film for terminals. When the heat shrinkage of the obtained adhesive film for metal terminals was measured, it showed a high value of 88.7%.

(Comparative Example 1)
As the polypropylene layer, an unstretched polypropylene film (CPP, total thickness 30 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (4 μm) / a block polypropylene layer (22 μm) / a random polypropylene layer (4 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on both sides of the unstretched polypropylene film by an extrusion laminating method, and an acid-modified polypropylene layer (35 μm) / polypropylene layer (30 μm) / acid-modified polypropylene layer (35 μm) was sequentially laminated. A laminated adhesive film for metal terminals was manufactured.

(Comparative Example 2)
As the polypropylene layer, an unstretched polypropylene film (CPP, total thickness 25 μm, melting peak temperature 155) having a three-layer structure in which a random polypropylene layer (3 μm) / a block polypropylene layer (3 μm) / a random polypropylene layer (19 μm) are laminated in this order. ℃) was prepared. Next, maleic anhydride-modified polypropylene was laminated on one side of the unstretched polypropylene film by an extrusion laminating method to produce an adhesive film for metal terminals in which an acid-modified polypropylene layer (41 μm) / polypropylene layer (25 μm) was laminated. bottom.

(Comparative Example 3)
As the polypropylene layer, a stretched polypropylene film (OPP, homopolypropylene, thickness 50 μm, melting peak temperature 165 ° C.) was prepared. Next, maleic anhydride-modified polypropylene was laminated on both sides of the stretched polypropylene film by an extrusion laminating method, and an acid-modified polypropylene layer (25 μm) / polypropylene layer (50 μm) / acid-modified polypropylene layer (25 μm) were laminated in this order. Manufactured an adhesive film for metal terminals.

When the cross sections of the unstretched polypropylene layers used in Examples 1 to 5 and Comparative Examples 1 and 2 were stained with ruthenium tetroxide (RuO ₄ ) and a scanning electron micrograph was observed, a sea-island structure was observed. On the other hand, when the stretched polypropylene layer used in Comparative Example 3 was observed in the same manner, no sea-island structure was observed.

(Manufacturing of packaging materials)
An aluminum foil (thickness 40 μm) was prepared by chemical conversion treatment (phosphate chromate treatment) on both sides with a chemical conversion treatment liquid consisting of a phenol resin, a chromium fluoride (trivalent) compound, and phosphoric acid. Next, one surface of the aluminum foil and a biaxially stretched nylon film (thickness 25 μm) were laminated via a urethane adhesive. Next, the other surface of the aluminum foil and the unstretched polypropylene film (thickness 30 μm) are sandwich-laminated with an acid-modified polypropylene resin (thickness 15 μm, graft-modified polypropylene with unsaturated carboxylic acid), and acid-modified polypropylene is subjected to hot air. Packaging in which biaxially stretched nylon film (25 μm) / aluminum foil (thickness 40 μm) / acid-modified polypropylene resin (thickness 15 μm) / unstretched polypropylene film (15 μm) are laminated in this order by heating to a temperature above the softening point of the resin. Manufactured the material. The above-mentioned seal strength was measured using the obtained packaging material.

In Table 1, PP means polypropylene and PPa means acid-modified polypropylene.

As shown in Table 1, it is composed of a laminate including at least one polypropylene layer and at least one acid-modified polypropylene layer, and the acid-modified polypropylene layer is formed on at least one side of the adhesive film for metal terminals. It constitutes the surface layer on the side, and the polypropylene layer has a sea-island structure when the cross section is observed by a scanning electron micrograph, and further, when the total thickness of the acid-modified polypropylene layer is 1, the polypropylene layer is formed. The adhesive films for metal terminals of Examples 1 to 5 having a total thickness in the range of 0.7 to 3.5 have a sealing strength (that is, adhesion) with the packaging material and the metal terminals. It can be seen that it is high and also has excellent electrolytic solution resistance. On the other hand, although the polypropylene layer has the above-mentioned sea-island structure, the total thickness of the polypropylene layer is outside the range of 0.7 to 3.5 when the total thickness of the acid-modified polypropylene layer is 1. The adhesive films for metal terminals of Examples 1 and 2 were inferior in adhesion to the packaging material and the metal terminals. Further, regarding the adhesive film for metal terminals of Comparative Example 3 which satisfies the above range but does not have the above-mentioned sea-island structure in the polypropylene layer, the adhesiveness to the packaging material and the metal terminals and the electrolytic solution resistance Was inferior to. Further, in Examples 1 to 7, the sea-island structure of the polypropylene layer had a large value of 28.0% or more when the island partial area was measured by binarization, and the acid-modified polypropylene layer was obtained. Also had a large value of 24.5% or more. On the other hand, in Comparative Example 3, when the island partial area of the polypropylene layer was measured by binarization, the area ratio was as low as 1.57%, and the polypropylene layer had a substantially sea-island structure. It was confirmed that it was not done.

1 Adhesive film for metal terminals 2 Metal terminals 3 Packaging material 3a Peripheral part of packaging material 4 Battery element 10 Battery 11 Polypropylene layer 12 Acid-modified polypropylene layer 31 Base material layer 32 Adhesive layer 33 Barrier layer 34 Heat-sealing resin layer 35 Adhesive layer P Center S Heat-sealed part

Claims (11)

An adhesive film for metal terminals interposed between a metal terminal electrically connected to an electrode of a battery element and a packaging material for sealing the battery element.
The adhesive film for metal terminals is composed of a laminate including at least one polypropylene layer and at least one acid-modified polypropylene layer.
The acid-modified polypropylene layer constitutes a surface layer on at least one side of the adhesive film for metal terminals.
When the cross section of the polypropylene layer was observed by electron micrograph, the sea-island structure was observed.
In the sea island structure of the polypropylene layer, the ratio of the area of the island portion is 10% or more and 50% or less.
An adhesive film for metal terminals in which the total thickness of the polypropylene layer is in the range of 0.7 or more and 3.5 or less when the total thickness of the acid-modified polypropylene layer is 1. The acid-modified polypropylene layer had a sea-island structure when the cross section was observed by electron micrograph.
The adhesive film for metal terminals according to claim 1, wherein in the sea-island structure of the acid-modified polypropylene layer, the ratio of the area of the island portion is 10% or more and 50% or less. The adhesive film for metal terminals according to claim 1 or 2, wherein the polypropylene layer contains block polypropylene. The adhesive film for metal terminals according to any one of claims 1 to 3, wherein the entire polypropylene layer is made of unstretched polypropylene. Claims 1 and 2 have a laminated structure in which a layer made of random polypropylene, a layer made of block polypropylene, and a layer made of random polypropylene are laminated in this order. , 4. Adhesive film for metal terminals according to any one of 4. The adhesiveness for metal terminals according to any one of claims 1 to 5, wherein a melting peak is observed in the range of 150 ° C. or higher and 165 ° C. or lower when the adhesive film for metal terminals is measured by a differential scanning calorimeter. the film. The adhesive film for metal terminals according to any one of claims 1 to 6, wherein the adhesive film for metal terminals has a residual thickness of 50% or more, which is measured by the following measuring method.
An aluminum plate having a thickness of 100 μm and an adhesive film for the metal terminal are prepared.
The thickness A (μm) of the adhesive film for metal terminals is measured.
The adhesive film for metal terminals is laminated on the central portion of the aluminum plate so that the length direction and the width direction of the aluminum plate and the adhesive film for metal terminals coincide with each other.
Prepare two metal plates longer than the length of the aluminum plate and having a width of 7 mm so as to cover the entire surface of the adhesive film for metal terminals, and heat the temperature from above and below the aluminum plate and the adhesive film for metal terminals. The metal plate is heated and pressurized under the conditions of 190 ° C., a surface pressure of 1.27 MPa, and a time of 3 seconds to obtain a laminate of the aluminum plate and the adhesive film for metal terminals.
The thickness B (μm) of the heated and pressurized portion of the laminate is measured.
The thickness residual ratio of the adhesive film for metal terminals is calculated by the following formula.
Thickness residual ratio (%) = (thickness B-100) / thickness A × 100 of adhesive film for metal terminals The adhesive film for metal terminals according to any one of claims 1 to 7, wherein the adhesive film for metal terminals has a heat shrinkage rate of 70 to 90% in the flow direction. The packaging material is composed of a laminate having at least a base material layer, a barrier layer, and a heat-sealing resin layer in this order.
The adhesive film for a metal terminal according to any one of claims 1 to 8, wherein the adhesive film for the metal terminal is interposed between the heat-sealing resin layer and the metal terminal. At least, a battery element having a positive electrode, a negative electrode, and an electrolyte, a packaging material for encapsulating the battery element, and a metal terminal electrically connected to each of the positive electrode and the negative electrode and projecting to the outside of the packaging material. It is a battery equipped with
A battery in which the adhesive film for metal terminals according to any one of claims 1 to 9 is interposed between the metal terminals and the packaging material. A method of using a laminate including at least one polypropylene layer and at least one acid-modified polypropylene layer.
The acid-modified polypropylene layer constitutes a surface layer on at least one side of the adhesive film for metal terminals.
When the cross section of the polypropylene layer was observed by electron micrograph, the sea-island structure was observed.
In the sea island structure of the polypropylene layer, the ratio of the area of the island portion is 10% or more and 50% or less.
When the total thickness of the acid-modified polypropylene layer is 1, the total thickness of the polypropylene layer is in the range of 0.7 or more and 3.5 or less.
A method of using the laminate as an adhesive film for metal terminals, which is interposed between a metal terminal electrically connected to an electrode of the battery element and a packaging material for sealing the battery element.

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