JP6648400B2 - Terminal resin film, tab and power storage device using the same - Google Patents

Description

  The present invention relates to a terminal resin film, a tab using the same, and a power storage device.

  In recent years, there has been an increasing demand for miniaturization of portable equipment and effective use of natural power generation energy, and research and development of lithium ion secondary batteries (a type of power storage device) that can obtain higher voltage and have high energy density have been conducted. I have.

  As a packaging material used for the lithium ion secondary battery, conventionally, metal cans have been often used.However, in response to demands for thinning and diversification of products to be applied, production costs are low, 2. Description of the Related Art A packaging material in which a laminate obtained by laminating a metal layer (for example, an aluminum foil) and a resin film in a bag shape has been used frequently.

  The laminated lithium-ion secondary battery in which the battery body is housed and sealed inside the packaging material is provided with a current extraction terminal called a tab. The tab is connected to the negative electrode or the positive electrode of the battery body and extends to the outside of the packaging material (sometimes referred to as a “tab lead”), and a terminal resin film covering a part of the outer peripheral surface of the metal terminal. (Sometimes referred to as “tab sealant”) (see, for example, Patent Documents 1 to 3). Usually, the terminal resin film is fused to the metal terminal.

  In recent years, there has been an increasing demand for insulating resin films for terminals and the like for use in vehicles and the like, and those having a multilayer structure have begun to be used. Further, when a terminal resin film is fused to a metal terminal to produce a tab, a protruding portion formed only of the terminal resin film protruding from the surface of the metal terminal is formed. The protruding portion plays a role in increasing the adhesion between the tab and the packaging material. In addition, for example, Patent Document 3 discloses that an elastomer is added to an insulating resin layer (tab sealant) to lower the tensile modulus, thereby increasing the flexibility of a sealing portion and reducing the force required when bending a lead wire at the sealing portion. It is stated to reduce.

JP 2008-4316 A JP 2010-218766 A JP 2009-259739 A

  The protruding portion of the terminal resin film has a problem that the terminal resin film is sagged and deformed before cooling after fusion of the terminal resin film to the metal terminal. In order to prevent this dripping, after fusion, there is also a method of cooling with the protruding portion fixed, but from the viewpoint of work efficiency, after fusion, only air cooling without fixing the protruding portion does not droop. There is a need to be able to make tabs. If the protruding portion hangs down, the handleability will deteriorate, and when positioning the tab lead using the shoulder of the tab sealant (the end of the protruding portion), the positioning accuracy will decrease, and in some cases the sensor There is a problem that does not respond. Further, if the protruding portion is deformed, cracks may occur in the terminal resin film during the production of the electric storage device, which may cause a short circuit. Up to now, no sufficient study has been made on the suppression of the sagging of the protruding portion of the terminal resin film. In addition, since the terminal resin film is distributed and used in a state of being wound up in a reel shape, it does not break at the time of winding up, has no wrinkles and cracks, and has good winding property. Required.

  The present invention has been made in view of the above-described problems of the related art, and has been described in which after a resin film for a terminal is fused to a metal terminal and before cooling, the protruding portion of the resin film for a terminal is deformed. An object of the present invention is to provide a terminal resin film that can be suppressed and has good winding properties, a tab using the same, and a power storage device.

  In order to achieve the above object, the present invention provides a terminal resin film for covering a part of the outer peripheral surface of a metal terminal constituting an electricity storage device, comprising a tensile storage elasticity at 120 ° C. in dynamic viscoelasticity measurement. Provided is a terminal resin film having a rate of 10 MPa to 1000 MPa.

  According to the terminal resin film, the terminal storage film having a configuration in which the tensile storage elastic modulus at 120 ° C. is 10 MPa to 1000 MPa is provided. Can be sufficiently suppressed that the protruding portion of the terminal resin film hangs down and deforms, and at the time of winding the terminal resin film into a reel shape, the occurrence of breaks, wrinkles, cracks, and the like can be suppressed, and good winding can be achieved. It is possible to realize the ease of taking. In addition, since the deformation of the protruding portion of the terminal resin film can be suppressed, it is possible to suppress the occurrence of cracks due to the deformation of the protruding portion in the terminal resin film at the time of manufacturing the power storage device, and the metal terminal and the packaging material It is possible to prevent a short circuit from occurring between them. Furthermore, since the deformation of the protruding portion of the terminal resin film can be suppressed, the handleability at the time of manufacturing the power storage device is improved, and the positioning accuracy of the tab is also improved.

  The terminal resin film of the present invention has a multilayer structure in which two or more layers are laminated, and includes, as at least one of the two or more layers, a heat-resistant layer containing a resin having a melting point of 200 ° C. or more. You may. Here, the heat-resistant layer preferably contains at least one selected from the group consisting of a polyester resin, a polycarbonate resin, a polyacetal resin and a polyamide resin as the resin having a melting point of 200 ° C. or higher.

  Further, the terminal resin film of the present invention has a multilayer structure in which two or more layers are laminated, and includes, as at least one of the two or more layers, a crosslinked layer containing a resin having a crosslinked structure. You may.

  Further, the terminal resin film of the present invention has a multilayer structure in which two or more layers are laminated, and at least one selected from the group consisting of fillers and fibers as at least one of the two or more layers. May be provided.

  Further, the terminal resin film of the present invention has a multilayer structure in which two or more layers are laminated, and at least one of the two or more layers is selected from the group consisting of block polypropylene and homopolypropylene. A layer containing at least one kind may be provided.

  Further, the terminal resin film of the present invention has a multilayer structure in which three or more layers are laminated, and at least one layer other than the outermost layer of the three or more layers is a group consisting of block polypropylene and homopolypropylene. An intermediate layer containing at least one selected from more may be provided.

  The terminal resin film of the present invention has a multilayer structure in which two or more or three or more layers including the above-described layers are laminated, so that the tensile storage modulus at 120 ° C. can be easily controlled in the range of 10 MPa to 1000 MPa. At the same time, the winding property can be improved. Further, by adjusting the configuration of each layer of the multilayer structure, it is possible to achieve both a high tensile storage modulus at 120 ° C. and adhesion to a metal terminal at a high level.

  The terminal resin film of the present invention preferably has an endothermic amount of 80 mJ / g or less when melted, as measured by a differential scanning calorimeter. When the heat absorption of the terminal resin film at the time of melting is 80 mJ / g or less, cooling after fusion to the metal terminal is accelerated, and deformation due to sagging can be more sufficiently suppressed.

  The resin film for a terminal of the present invention has a value of E1 / E2 of 1 when the tensile storage modulus at 120 ° C. is E1 and the tensile storage modulus at 25 ° C. is E2 in the dynamic viscoelasticity measurement. / 20 or more. When the value of E1 / E2 of the terminal resin film is 1/20 or more, the tensile storage elastic modulus at high temperatures does not become too low, so that the protruding portion of the terminal resin film is more effectively prevented from sagging and deforming. There is an advantage that it can be suppressed.

  The terminal resin film of the present invention is preferably formed by inflation molding. When the terminal resin film is formed by inflation molding, the film is easily crystallized, and is stretched and oriented not only in the flow direction but also in the width direction during film formation. The storage modulus is improved.

  The present invention also provides a tab including a metal terminal and the above-mentioned terminal resin film of the present invention arranged so as to cover an outer peripheral surface of a part of the metal terminal. Since such a tab uses the terminal resin film of the present invention, the deformation of the protruding portion of the terminal resin film is suppressed. It is possible to suppress the occurrence in the resin film, and it is possible to prevent a short circuit from occurring between the metal terminal and the packaging material. Further, the tabs have good handleability and positioning accuracy when manufacturing the electric storage device.

  In the tab of the present invention, when the length of the protruding portion of the terminal resin film from the metal terminal is L, L may be 1 mm or more. When the width L of the protruding portion is 1 mm or more, the protruding portion is easily deformed by sagging, but according to the present invention, even if the width L of the protruding portion is 1 mm or more, it is possible to sufficiently suppress the occurrence of sagging. it can. Further, when the width L of the protruding portion is 1 mm or more, there is an advantage that the adhesion between the tab and the packaging material is improved.

  The present invention further provides an electricity storage device including the tab of the present invention. Since such a power storage device uses the tab of the present invention, occurrence of a short circuit between the metal terminal and the packaging material is sufficiently suppressed.

  According to the present invention, after the terminal resin film is fused to the metal terminal and before cooling, the protrusion of the terminal resin film can be suppressed from being deformed, and the winding property is good. A certain terminal resin film, a tab using the same, and a power storage device can be provided.

FIG. 1 is a perspective view illustrating a schematic configuration of a power storage device according to an embodiment of the present invention. It is sectional drawing which shows an example of the cut surface of the packaging material shown in FIG. FIG. 2 is a cross-sectional view of the terminal resin film and the metal terminal shown in FIG. 1 taken along line AA. FIG. 4 is a view showing a tab formed by fusing a terminal resin film to a metal terminal.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts have the same reference characters allotted, and overlapping description will be omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a perspective view showing a schematic configuration of the electric storage device according to the embodiment of the present invention. In FIG. 1, a lithium ion secondary battery is shown as an example of the power storage device 10, and the following description will be given. Note that the lithium ion secondary battery having the configuration illustrated in FIG. 1 may be referred to as a battery pack or a battery cell.

  The power storage device 10 shown in FIG. 1 is a lithium ion secondary battery, and includes a power storage device main body 11, a packaging material 13, a pair of metal terminals 14 (tab leads), a terminal resin film 16 (tab sealant), Having.

  The power storage device main body 11 is a battery main body that performs charging and discharging. The packaging material 13 is arranged so as to cover the surface of the power storage device main body 11 and contact a part of the terminal resin film 16.

  FIG. 2 is a sectional view showing an example of a cut surface of the packaging material shown in FIG. 2, the same components as those of the structure shown in FIG. 1 are denoted by the same reference numerals.

  Here, an example of the configuration of the packaging material 13 will be described with reference to FIG. The packaging material 13 includes an inner layer 21, an inner adhesive layer 22, a corrosion prevention treatment layer 23-1, a barrier layer 24 as a metal layer, and a corrosion prevention treatment layer 23 from the inside in contact with the power storage device body 11. -2, an outer-layer-side adhesive layer 25, and an outer layer 26 are sequentially laminated to form a seven-layer structure.

  As the base material of the inner layer 21, for example, a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modified maleic anhydride or the like to a polyolefin resin can be used. As the polyolefin resin, for example, low-, medium-, and high-density polyethylene; ethylene-α-olefin copolymer; homo, block, or random polypropylene; propylene-α-olefin copolymer and the like can be used. These polyolefin resins may be used alone or in combination of two or more.

  Further, the inner layer 21 may be configured using a single-layer film or a multilayer film in which a plurality of layers are laminated according to a required function. Specifically, for example, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed may be used in order to impart moisture resistance. Further, the inner layer 21 may include, for example, various additives (for example, a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and the like).

  The thickness of the inner layer 21 is preferably set, for example, within a range of 10 to 150 μm, and more preferably 30 to 80 μm. If the thickness of the inner layer 21 is smaller than 10 μm, the heat seal adhesion between the packaging materials 13 and the adhesion with the terminal resin film 16 may be reduced. Further, if the thickness of the inner layer 21 is larger than 150 μm, the cost of the packaging material 13 increases, which is not preferable.

  As the inner adhesive layer 22, for example, a known adhesive such as a general adhesive for dry lamination or an acid-modified heat-fusible resin can be appropriately selected and used.

  As shown in FIG. 2, the corrosion prevention treatment layers 23-1 and 23-2 are preferably formed on both surfaces of the barrier layer 24 from the viewpoint of performance. However, in consideration of cost, the corrosion prevention treatment layers 23-1 and 23-2 are formed on the inner adhesive layer 22 side. The corrosion prevention treatment layer 23-1 may be arranged only on the surface of the barrier layer 24 located.

  The barrier layer 24 is a conductive metal layer. As a material of the barrier layer 24, for example, aluminum, stainless steel, or the like can be exemplified. However, aluminum is preferable in terms of cost, weight (density), and the like.

  As the outer layer-side adhesive layer 25, for example, a general polyurethane-based adhesive mainly composed of polyester polyol, polyether polyol, acrylic polyol or the like can be used.

  As the outer layer 26, for example, a single layer film such as nylon or polyethylene terephthalate (PET) or a multilayer film can be used. The outer layer 26 may include, for example, various additives (for example, a flame retardant, a slip agent, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and the like), like the inner layer 21. Further, the outer layer 26 may have a protective layer formed by, for example, laminating a resin insoluble in the electrolytic solution or coating a resin component insoluble in the electrolytic solution as a measure against liquid leakage. .

  FIG. 3 is a cross-sectional view of the terminal resin film and the metal terminal shown in FIG. 1 taken along the line AA. 3, the same components as those of the structure shown in FIG. 1 are denoted by the same reference numerals.

  As shown in FIGS. 1 and 3, the pair of (two in the case of FIG. 1) metal terminals 14 include a metal terminal main body 14-1 and a corrosion prevention layer 14-2. One of the pair of metal terminal bodies 14-1 is electrically connected to the positive electrode of the power storage device body 11, and the other metal terminal body 14-1 is connected to the power storage device body 11. Is electrically connected to the negative electrode. The pair of metal terminal bodies 14-1 extend in a direction away from the power storage device body 11, and a part thereof is exposed from the packaging material 13. The shape of the pair of metal terminal bodies 14-1 may be, for example, a flat plate shape.

  Metal can be used as the material of the metal terminal body 14-1. It is preferable that the metal used as the material of the metal terminal body 14-1 is determined in consideration of the structure of the power storage device main body 11, the material of each component of the power storage device main body 11, and the like.

  For example, when the power storage device 10 is a lithium ion secondary battery, aluminum is used as the positive electrode current collector, and copper is used as the negative electrode current collector. In this case, it is preferable to use aluminum as the material of the metal terminal body 14-1 connected to the positive electrode of the power storage device body 11. In consideration of corrosion resistance to the electrolytic solution, it is preferable to use, for example, an aluminum material having a purity of 97% or more, such as 1N30, as a material of the metal terminal body 14-1 connected to the positive electrode of the power storage device body 11. is there. Further, when bending the metal terminal body 14-1, it is preferable to use an O material that has been tempered by sufficient annealing for the purpose of adding flexibility. As a material of the metal terminal body 14-1 connected to the negative electrode of the power storage device body 11, it is preferable to use copper or nickel having a nickel plating layer formed on the surface.

  The thickness of the metal terminal body 14-1 depends on the size and capacity of the lithium ion secondary battery. When the lithium ion secondary battery is small, the thickness of the metal terminal body 14-1 may be, for example, 50 μm or more. In the case of a large-sized lithium ion secondary battery for power storage / vehicle use, the thickness of the metal terminal body 14-1 can be appropriately set within a range of, for example, 100 to 500 μm.

The corrosion prevention layer 14-2 is disposed so as to cover the surface of the metal terminal body 14-1. In the case of a lithium ion secondary battery, the electrolytic solution contains a corrosive component such as LiPF ₆ . Corrosion layer 14B is a layer for preventing the metal terminal body 14-1 is corroded from corrosive components, such as LiPF ₆ contained in the electrolytic solution.

  As shown in FIG. 3, the terminal resin film 16 is arranged so as to cover a part of the outer peripheral surface of the metal terminal 14. In the present embodiment, the terminal resin film 16 includes a first outermost layer 31 that contacts the outer peripheral side surface of the metal terminal 14, a second outermost layer 32 that contacts the packaging material 13, and a first outermost layer 31. An intermediate layer 33 disposed between the second outermost layer 32 and the second outermost layer 32 is laminated. The terminal resin film 16 may be composed of one or two layers, or may be composed of four or more layers.

  The first outermost layer 31 is disposed so as to cover the outer peripheral surface of the metal terminal 14, thereby sealing the circumferential direction of the metal terminal 14 and making the terminal resin film 16 and the metal terminal 14 adhere to each other. Having.

  Although the constituent material of the first outermost layer 31 is not particularly limited, for example, it is preferable to use a resin having excellent adhesiveness. As the resin material constituting the first outermost layer 31, for example, a polyolefin resin or an acid-modified polyolefin resin obtained by graft-modifying maleic anhydride or the like to the polyolefin resin can be used.

  Here, the polyolefin resin is preferably a polyolefin random copolymer from the viewpoint of adhesiveness. The polyolefin random copolymer is obtained by randomly copolymerizing two or more olefin monomers. Examples of the olefin monomer include ethylene, propylene, 1-butene, and the like.

  Specific examples of the polyolefin random copolymer include, for example, an ethylene-propylene random copolymer which is a copolymer of propylene and ethylene, a 1-butene-propylene random copolymer which is a copolymer of propylene and 1-butene, and propylene and ethylene. Ethylene-butene-propylene random terpolymer which is a copolymer of styrene and 1-butene. Among these, an ethylene-propylene random copolymer is preferred.

  In the ethylene-propylene random copolymer and the acid-modified product thereof, the ethylene content is preferably from 0.1 to 10% by mass, more preferably from 1 to 7% by mass, and preferably from 2 to 5% by mass. More preferred. When the ethylene content is 0.1% by mass or more, the effect of lowering the melting point by copolymerizing ethylene is sufficiently obtained, and the adhesiveness when the terminal resin film is melted at low temperature to the metal terminal tends to be improved. There is. When the ethylene content is 10% by mass or less, the melting point can be prevented from being too low, and the liquid storage device tends to have improved liquid leakage prevention when the power storage device is held in a high-temperature environment for a long period of time. The ethylene content can be calculated from the mixing ratio of the monomers at the time of polymerization.

  The melting point of the polyolefin random copolymer and the acid-modified product thereof is preferably from 120 to 145 ° C, more preferably from 125 to 140 ° C. When the melting point is 120 ° C. or higher, the tensile storage modulus of the terminal resin film can be easily controlled within the range of 10 MPa to 1000 MPa, and the liquid storage device can prevent liquid leakage when the power storage device is held in a high-temperature environment for a long time. Tends to improve. When the melting point is 145 ° C. or lower, the adhesiveness when the terminal resin film is fusion-bonded to the metal terminal at a low temperature tends to be improved. In addition, in this specification, a melting point can be measured by a differential scanning calorimeter (DSC).

  The weight average molecular weight of the polyolefin random copolymer and the acid-modified product thereof is preferably adjusted as appropriate so that the melting point falls within the above range, but is preferably 5,000 to 10,000,000, more preferably 10,000. 000 to 1,000,000. In addition, in this specification, a weight average molecular weight can be calculated | required by measuring by gel permeation chromatography (GPC) and converting by the calibration curve using standard polystyrene.

  The melt mass flow rate (MFR) of the polyolefin random copolymer and the acid-modified product thereof is 0.5 to 15 g / 10 min from the viewpoint of making it easy to control the tensile storage modulus of the terminal resin film within the range of 10 MPa to 1000 MPa. And more preferably 1 to 10 g / 10 min. In the present specification, the melt mass flow rate (MFR) can be determined according to JIS K7210.

  The first outermost layer 31 preferably contains an acid-modified polyolefin random copolymer as the polyolefin random copolymer. By using an acid-modified polyolefin as a constituent material of the first outermost layer 31, the adhesion to the metal terminal 14 can be further improved. As the acid-modified polyolefin, for example, an acid-modified polyolefin obtained by graft modification of maleic anhydride or the like can be used. In addition, the first outermost layer 31 may include two or more types of polyolefins, and may further include components other than the polyolefins as necessary. The polyolefin may include a polyolefin block copolymer or a polyolefin homopolymer, in addition to the polyolefin random copolymer. Among the polyolefins contained in the first outermost layer 31, the proportion of the polyolefin random copolymer and its acid-modified product is determined to improve the adhesion when the terminal resin film is fused to the metal terminal (particularly when the terminal resin film is fused at a low temperature). In light of the above, the content is preferably 25% by mass or more, and more preferably 50% by mass or more.

  The thickness of the first outermost layer 31 is preferably from 10 to 100 μm, and more preferably from 15 to 50 μm. If the thickness of the first outermost layer 31 is smaller than 10 μm, the adhesion to the metal terminal 14 may be reduced. On the other hand, if the thickness of the first outermost layer 31 is more than 100 μm, it is not preferable because the cost of the terminal resin film 16 is increased.

  The second outermost layer 32 has a function of sealing the inside of the packaging material 13 by being fused with the packaging material 13. The second outermost layer 32 preferably has the same configuration as the above-described first outermost layer 31 from the viewpoint of adhesion to the packaging material 13.

  The intermediate layer 33 is disposed between the first outermost layer 31 and the second outermost layer 32. The intermediate layer 33 has one surface covered with a first outermost layer 31 and the other surface covered with a second outermost layer 32.

  The configuration of the intermediate layer 33 is not particularly limited, but preferably has a configuration capable of adjusting the tensile storage modulus at 120 ° C. of the terminal resin film 16 within a range of 10 MPa to 1000 MPa. In particular, when the first outermost layer 31 and the second outermost layer 32 are formed of a polyolefin random copolymer or an acid-modified product thereof, the tensile storage elasticity tends to be low. It is preferable to have a configuration capable of increasing the rate. Therefore, the intermediate layer 33 is preferably a layer containing at least one selected from the group consisting of block polypropylene and homopolypropylene.

  In the present invention, block polypropylene means a state in which polyethylene, ethylene-propylene rubber (EPR) and the like are dispersed in homopolypropylene. The block polypropylene has a structure (sea-island structure) in which EPR and polyethylene are dispersed in an island shape in homopolypropylene. As the block polypropylene, block polypropylene in which polyethylene is dispersed in homopolypropylene is preferable.

  In the block polypropylene, the ethylene content is preferably from 0.1 to 10% by mass, more preferably from 1 to 7% by mass, and still more preferably from 2 to 5% by mass. When the ethylene content is 0.1% by mass or more, the adhesiveness when the terminal resin film is fusion-bonded to the metal terminal at a low temperature tends to be improved. When the ethylene content is 10% by mass or less, the tensile storage modulus at 120 ° C. of the terminal resin film 16 tends to be improved, and the melting point of the block polypropylene can be suppressed from being excessively lowered. There is a tendency that the liquid leakage prevention property when held for a long time in an environment is improved.

  The melting point of the block polypropylene is preferably from 130 to 165 ° C, more preferably from 135 to 155 ° C, even more preferably from 140 to 150 ° C. When the melting point is 130 ° C. or higher, the tensile storage modulus at 120 ° C. of the terminal resin film 16 tends to be improved, and the liquid leakage preventing property when the power storage device is held in a high temperature environment for a long time is improved. Tend to. When the melting point is 165 ° C. or lower, the adhesiveness when the terminal resin film is fusion-bonded to the metal terminal at a low temperature tends to be improved.

  The weight average molecular weight of the block polypropylene is preferably adjusted as appropriate so that the melting point falls within the above range, but is preferably from 5,000 to 10,000,000, and more preferably from 10,000 to 1,000,000. 000.

  Homopolypropylene is a homopolymer of propylene. The melting point of the homopolypropylene is preferably from 140 to 165C, more preferably from 145 to 163C, even more preferably from 150 to 160C. When the melting point is 140 ° C. or higher, the tensile storage elastic modulus of the terminal resin film 16 at 120 ° C. tends to be improved, and the liquid leakage prevention property when the power storage device is held in a high temperature environment for a long time is improved. Tend to. When the melting point is 165 ° C. or lower, the adhesiveness when the terminal resin film is fusion-bonded to the metal terminal at a low temperature tends to be improved.

  The weight average molecular weight of the homopolypropylene is preferably adjusted as appropriate so that the melting point falls within the above range, but is preferably from 5,000 to 10,000,000, and more preferably from 10,000 to 1,000,000. 000.

  The intermediate layer 33 may include two or more types of block polypropylenes and two or more types of homopolypropylenes, may include other polyolefins, and may include components other than polyolefins. Other polyolefins include polyolefin block copolymers other than block polypropylene, polyolefin homopolymers other than homopolypropylene, and polyolefin random copolymers. When it is desired to improve the insulating property of the intermediate layer 33, for example, a polyester such as PET (polyethylene terephthalate) or a heat-resistant resin (for example, polycarbonate) may be used as a component other than the polyolefin. When other polyolefins are used, the total content of block polypropylene and homopolypropylene among the polyolefins contained in the intermediate layer 33 is from the viewpoint of increasing the tensile storage modulus at 120 ° C. of the terminal resin film 16. , 25% by mass or more, and more preferably 50% by mass or more.

  Further, the intermediate layer 33 may be a layer having a configuration other than the above. The intermediate layer 33 is, from the viewpoint of increasing the tensile storage modulus at 120 ° C. of the terminal resin film 16, a layer containing a resin having a melting point of 200 ° C. or more (heat-resistant layer) and a layer containing a resin having a cross-linked structure (cross-linked layer). ), A layer containing at least one selected from the group consisting of fillers and fibers (reinforced layer), or a layer satisfying at least one of the requirements. Further, these heat-resistant layer, crosslinked layer and reinforcing layer may further contain at least one selected from the group consisting of block polypropylene and homopolypropylene.

  Examples of the resin having a melting point of 200 ° C. or more in the heat-resistant layer include polyester resin, polycarbonate resin, polyacetal resin, polyamide resin, polyvinyl alcohol resin, polyvinylidene chloride resin, polyvinylidene fluoride resin, and the like. These can be used alone or in combination of two or more.

  Examples of the resin having a crosslinked structure in the crosslinked layer include a crosslinked acrylic resin, an epoxy resin, a phenol resin, a urea resin, a melamine resin, and a polyurethane resin. These can be used alone or in combination of two or more.

  In the reinforcing layer, examples of the filler include silica particles, alumina particles, barium sulfate particles, and calcium carbonate particles. These can be used alone or in combination of two or more. From the viewpoint of further increasing the tensile storage modulus at 120 ° C. of the terminal resin film 16, the average particle size of the filler is preferably 0.1 to 10 μm, and the content of the filler is the total amount of the reinforcing layer (intermediate layer 33). Is preferably 0.5 to 20% by mass on the basis of

  In the reinforcing layer, examples of the fiber include a fiber made of a cellulose resin or a resin having a melting point of 200 ° C. or more used for the heat-resistant layer. These can be used alone or in combination of two or more. In order to further increase the tensile storage modulus at 120 ° C. of the terminal resin film 16, the fiber width of the fiber is preferably 10 nm to 10 μm, and the content of the fiber is based on the total amount of the reinforcing layer (middle layer 33). It is preferably from 0.5 to 70% by mass. Further, the fibers may form a nonwoven fabric.

  The reinforcing layer may be a layer in which the above-mentioned filler and / or fiber is dispersed in the above-mentioned polyolefin resin, a resin having a melting point of 200 ° C. or more, a resin having a crosslinked structure, or the like.

  The melt mass flow rate (MFR) of the resin (polyolefin resin, resin having a melting point of 200 ° C. or higher and resin having a crosslinked structure) used for the intermediate layer 33 is such that the tensile storage modulus of the terminal resin film is in the range of 10 MPa to 1000 MPa. From the viewpoint of easy control, it is preferably 0.3 to 10 g / 10 min, and more preferably 1 to 5 g / 10 min.

  The intermediate layer 33 does not need to have a single-layer structure, and may have a multi-layer structure in which a plurality of resin layers are bonded together via an adhesive, for example. Therefore, the intermediate layer 33 may have a multilayer structure including at least two layers selected from the group consisting of block polypropylene and homopolypropylene, a heat-resistant layer, a crosslinked layer, and a reinforcing layer.

  The thickness of the intermediate layer 33 (the entire thickness in the case of a multilayer structure) can be appropriately set within a range of, for example, 10 to 200 μm, and is preferably 20 to 100 μm. It is important that the thickness of the intermediate layer 33 be balanced with the thicknesses of the metal terminal 14 and the first outermost layer 31, and when the thickness of the first outermost layer 31 and the metal terminal 14 is large, the thickness of the intermediate layer 33 is small. The thickness of 33 may also be increased accordingly.

  At least one of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 is preferably colored. Coloring can be performed, for example, by adding a pigment to each layer. As described above, by coloring one or more of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33, compared to a terminal resin film in which no pigment is added to any of the layers. Thus, the visibility of the terminal resin film 16 can be improved. Thereby, the inspection of the terminal resin film 16 (specifically, for example, an inspection of whether or not the terminal resin film 16 is attached to the metal terminal 14, an inspection of an attachment position of the terminal resin film 16 with respect to the metal terminal 14) Etc.) can be improved.

  As the pigment, for example, an organic pigment or an inorganic pigment can be used. Examples of the organic pigment include, for example, azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigothioindigo-based, perinone-perylene-based, and isoindolenin-based pigments.Examples of the inorganic pigment include carbon black-based pigments. And titanium oxide-based, cadmium-based, lead-based and flour-oxide-based powders. In addition, mica (mica) fine powder, fish scale foil and the like can be used.

  As specific examples of the organic pigment, for example, the following pigments can be used. As the organic pigment that can be colored yellow, for example, isoindolinone, isoindoline, quinophthalone, anthraquinone (flavatron), azomethine, xanthene, and the like can be used. As the organic pigment that can be colored orange, for example, diketopyrrolopyrrole, perylene, anthraquinone, perinone, quinacridone and the like can be used. As the organic pigment that can be colored red, for example, anthraquinone, quinacridone, diketopyrrolopyrrole, perylene, indigoid and the like can be used. As the organic pigment that can be colored purple, for example, oxazine (dioxazine), quinacridone, perylene, indigoid, anthraquinone, xanthene, benzimidazolone, biolanthrone and the like can be used. As an organic pigment that can be colored blue, for example, phthalocyanine, anthraquinone, indigoid and the like can be used. As an organic pigment that can be colored green, for example, phthalocyanine, perylene, azomethine, or the like can be used.

  As specific examples of the inorganic pigment, for example, the following pigments can be used. As the inorganic pigment that can be colored white, for example, zinc white, lead white, lithopone, titanium dioxide, precipitated barium sulfate, barite powder and the like can be used. As the inorganic pigment that can be colored red, for example, lead red, iron oxide red and the like can be used. As the inorganic pigment that can be colored yellow, for example, graphite, zinc yellow (one kind of zinc yellow, two kinds of zinc yellow) and the like can be used. As an inorganic pigment that can be colored blue, for example, ultramarine blue, procyan blue (potassium iron ferrocyanide), or the like can be used. As the inorganic pigment that can be colored black, for example, carbon black or the like can be used.

  The content of the organic pigment and the inorganic pigment contained in at least one of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 is in the range of 0.01% by mass to 3.00% by mass. Can be set as appropriate.

  As the pigment, for example, it is preferable to use carbon black. As described above, by adding carbon black to at least one of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33, it is possible to obtain a dark color (specifically, black). Becomes

  As a result, the visibility of the terminal resin film 16 is further improved, so that the terminal resin film 16 is inspected (specifically, for example, whether or not the terminal resin film 16 is attached to the metal terminal 14; Inspection of the mounting position of the terminal resin film 16 with respect to the metal terminals 14 can be performed with higher accuracy. This is particularly effective when the width of the metal terminal 14 is small and the width of the terminal resin film 16 is small.

  The particle size of the carbon black serving as a pigment can be appropriately selected, for example, within a range of 1 nm to 1 μm. The amount of carbon black contained in at least one of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 may be, for example, 0.01% by mass or more and 3.00% by mass or less. If the amount of carbon black is less than 0.01% by mass or more, it will be difficult to color each layer in a dark shade. When the content of carbon black is more than 3.00% by mass, the conductivity of each layer becomes too high, so that it is difficult to sufficiently secure electrical insulation between each layer and the metal terminal 14. Will be.

  Therefore, by adjusting the addition amount of carbon black contained in at least one of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 to 0.01% by mass or more and 3.00% by mass or less, the terminal The visibility of the resin film 16 for use can be improved, and electrical insulation can be sufficiently ensured.

  When a conductive pigment such as carbon black is used as the pigment, it is necessary that at least one of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 does not contain the pigment. It is preferable from the viewpoint of ensuring the properties.

  The total thickness of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 is from the viewpoint of easily setting the tensile storage modulus at 120 ° C. of the terminal resin film 16 to a range of 10 MPa to 1000 MPa. It is preferably from 10 to 500 μm, more preferably from 30 to 200 μm.

  The terminal resin film 16 having the above-mentioned laminated structure has a tensile storage elastic modulus at 120 ° C. of 10 MPa to 1000 MPa in dynamic viscoelasticity measurement (DMA: Dynamic Mechanical Analysis). Here, the tensile storage elastic modulus is a value measured in accordance with JIS K7244-4 (Plastic—Testing method for dynamic mechanical properties—Tensile vibration—Non-resonance method). This is a value (tensile storage modulus E ′) measured on a test piece obtained by cutting the film 16 to a width of 10 mm and a length of 20 mm using a dynamic viscoelastic apparatus at a temperature of 120 ° C. and a frequency of 1 Hz. In this measurement method, a sine wave is applied while holding the upper and lower ends of the test piece, and viscoelasticity is measured from the response. When the tensile storage elastic modulus is 10 MPa or more, after the terminal resin film 16 is fused to the metal terminal 14, the sagging of the protruding portion of the terminal resin film 16 before cooling is sufficiently suppressed. can do. On the other hand, when the tensile storage elastic modulus is 1000 MPa or less, the terminal resin film 16 has a sufficient elastic deformation region, and when the terminal resin film 16 is wound into a reel, it may be broken, wrinkled, cracked, or the like. Can be suppressed, and a good winding property can be realized. From the viewpoint of obtaining these effects more sufficiently, the tensile storage elastic modulus at 120 ° C. of the terminal resin film 16 is preferably 20 MPa to 900 MPa, and more preferably 30 MPa to 500 MPa. As the measurement direction of the film, the MD (flow) direction and the TD (width) direction are generally used, but it is more preferable that at least one, and preferably both, of MD and TD are included in the above range.

  Here, FIG. 4 is a view showing the tab 20 formed by fusing the terminal resin film 16 to the metal terminal 14. FIG. 4A is a perspective view showing the tab 20 in a state where the protruding portion 16a is not deformed, and FIG. 4B is a cross-sectional view taken along line BB of FIG. 4A. (C) is a cross-sectional view showing the tab 20 in a state where the protruding portion 16a is sagged and deformed. As described above, if the tensile storage modulus at 120 ° C. of the terminal resin film 16 is less than 10 MPa, the protruding portion 16a sags as shown in FIG. 4C. This sagging tends to occur as the width L of the protruding portion increases, and sagging tends to occur when the width L is 1 mm or more. According to the present invention, even if the width L of the protruding portion is 1 mm or more, it is possible to sufficiently suppress the occurrence of sagging. Further, when the width L of the protruding portion is 3 mm or more, the occurrence of sagging is particularly remarkable. Even in such a case, according to the present invention, the occurrence of sagging can be sufficiently suppressed. Further, when the width L of the protruding portion is 1 mm or more, particularly 3 mm or more, there is an advantage that the adhesion between the tab 20 and the packaging material 13 is improved. The occurrence of the sag can be evaluated by the deformation amount D shown in FIG. The amount of deformation D can be determined from the difference in height between the upper end d1 and the lower end d2 of the lower surface of the deformed protruding portion 16a. When the amount of deformation D is large, stress is likely to be applied to the terminal resin film 16 during the production of the electric storage device, and cracks are generated, so that insulation between the metal terminal 14 and the packaging material 13 cannot be secured, and short-circuiting is likely to occur. Become. In particular, when the ratio (D / L) of the deformation amount D to the width L of the protruding portion is 0.5 or more, the occurrence rate of short-circuit of the power storage device tends to increase.

  When the tensile storage modulus at 120 ° C. in the dynamic viscoelasticity measurement is E1 and the tensile storage modulus at 25 ° C. is E2 in the dynamic viscoelasticity measurement, the value of E1 / E2 is 1/20. It is preferably at least, more preferably at least 1/10. When the value of E1 / E2 is 1/20 or more, the tensile storage modulus at high temperature does not become too low, so that it is possible to more effectively suppress the protruding portion of the terminal resin film from being sagged and deformed. There is an advantage that you can. The tensile storage modulus E2 at 25 ° C. of the terminal resin film 16 is not particularly limited as long as the value of E1 / E2 falls within the above range, but is preferably 10 GPa or less, and is preferably 100 MPa to 5 GPa. Preferably, the pressure is 200 MPa to 2 GPa. The measurement conditions of the tensile storage modulus E2 at 25 ° C. are the same as the measurement conditions of the tensile storage modulus E1 at 120 ° C. except for the temperature conditions.

  The terminal resin film 16 preferably has a heat absorption (melting heat) of 80 mJ / g or less, more preferably 60 mJ / g or less, when measured by a differential scanning calorimeter (DSC). The endothermic amount at the time of melting was determined by a differential scanning calorimeter from the area of the endothermic peak in the range of 80 ° C to 170 ° C in the scanning temperature range of 10 ° C / min. Is the value divided by the mass of When the heat absorption during melting is 80 mJ / g or less, the cooling after the terminal resin film 16 is fused to the metal terminal 14 is quickened, and the deformation due to dripping can be more sufficiently suppressed.

  Next, a method of manufacturing the terminal resin film 16 of the present embodiment will be briefly described. The method for producing the terminal resin film 16 is not particularly limited. The terminal resin film 16 can be manufactured using, for example, a film extrusion manufacturing apparatus having a die such as a round die used when using the inflation molding method or a T die used when using the press die method. Although it is possible, a multilayer inflation molding method is preferred.

  Generally, a material having a melt mass flow rate (hereinafter, referred to as “MFR”) of 5 g / 10 min or less is often used as a material of the terminal resin film 16. For this reason, when the T-die method is used, film formation is not stable, and production is often difficult. On the other hand, the inflation molding method is suitable for the production of the terminal resin film 16 because the film can be stably formed even with the above-mentioned material (MFR having a value of 5 g / 10 min or less). In addition, when the film is formed by inflation molding, the terminal resin film 16 is easily crystallized, and is stretched and oriented not only in the flow direction but also in the width direction during film formation. Can improve the tensile storage modulus of the rubber.

  In the following description, as an example of a method of manufacturing the terminal resin film 16, a case where the terminal resin film 16 is manufactured using an inflation molding method (in other words, an inflation molding device) will be described.

  First, a base material of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 is prepared. Next, the base materials of the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 are supplied to an inflation molding apparatus. Next, the three base materials are extruded from an extruded part of the inflation molding apparatus so as to form a three-layer structure (a structure in which the first outermost layer 31, the second outermost layer 32, and the intermediate layer 33 are laminated). Then, air (air) is supplied from the inside of the extruded three-layer structure laminate.

  Then, while transporting the cylindrical terminal resin film 16 inflated into a cylindrical shape, the terminal resin film 16 is deformed into a flat shape by the guide portion, and then the terminal resin film 16 is folded into a sheet shape by a pair of pinch rolls. Both ends of the woven tube are slit, and a pair of (two strips) films are wound into a roll around a winding core, whereby the roll-shaped terminal resin film 16 is manufactured.

  The extrusion temperature at the time of manufacturing the terminal resin film 16 is preferably, for example, in the range of 170 to 300 ° C, and more preferably 200 to 250 ° C. When the extrusion temperature is less than 170 ° C., the resin constituting each layer is insufficiently melted, so that the melt viscosity becomes considerably large, so that extrusion from the screw may become unstable. On the other hand, when the extrusion temperature is higher than 300 ° C., the resin constituting each layer is greatly oxidized and deteriorated, so that the quality of the terminal resin film 16 is deteriorated.

  The screw rotation speed, blow ratio, take-up speed, and the like can be appropriately set in consideration of the set film thickness. The thickness ratio of each layer of the terminal resin film 16 can be easily adjusted by changing the rotation speed of each screw.

  Note that the terminal resin film 16 of the present embodiment may be manufactured by dry lamination using an adhesive or a method of laminating formed insulating layers (insulating films) by sandwich lamination.

  Here, with reference to FIG. 3, a description will be given of a fusion bonding process for melting and bonding the terminal resin film 16 and the metal terminal 14 according to the present embodiment. In the fusion bonding process, the terminal resin film 16 and the metal terminal 14 are bonded while simultaneously melting the first outermost layer 31 by heating and closely contacting the first outermost layer 31 with the metal terminal 14 by pressing. Heat fusion.

  Further, in the above-mentioned fusion bonding process, in order to obtain sufficient adhesion and sealing property between the terminal resin film 16 and the metal terminal 14, the heating is performed to a temperature equal to or higher than the melting point of the resin constituting the first outermost layer 31. Do.

  Specifically, for example, 140 to 170 ° C. can be used as the heating temperature of the terminal resin film 16. Further, the processing time (the total time of the heating time and the pressing time) needs to be determined in consideration of the peel strength and the productivity. The processing time can be appropriately set, for example, within a range of 1 to 60 seconds.

  When the production tact (productivity) of the terminal resin film 16 is prioritized, the heat bonding may be performed at a temperature exceeding 170 ° C. with a short pressing time. In this case, as the heating temperature, for example, 170 to 230 ° C. can be used, and as the pressurizing time, for example, 3 to 20 seconds can be used.

  As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.

  For example, in FIG. 3, the terminal resin film 16 having a three-layer structure is described as an example. However, the intermediate resin layer 33 and the first outermost layer 31 and the intermediate layer 33 and the second outermost layer 31 are described. 32, a second intermediate layer made of an insulating resin or the like may be provided.

  As described above, the second intermediate layer is disposed between the intermediate layer 33 and the first outermost layer 31 and between the intermediate layer 33 and the second outermost layer 32 to form a multilayer structure of four or more layers. By doing so, the insulation between the intermediate layer 33 and the barrier layer 24 (metal layer) constituting the packaging material 13 and the insulation between the intermediate layer 33 and the metal terminals 14 can be improved. Note that the second intermediate layer may be the above-described heat-resistant layer, cross-linked layer, or reinforcing layer.

  The terminal resin film 16 may be composed of one or two layers.

  When the terminal resin film 16 has a single-layer (single-layer) structure, the single layer can have the same configuration as the first outermost layer 31 described above. In this case, it is preferable to use a relatively high melting point polyolefin random copolymer or an acid-modified product thereof so that the terminal resin film 16 has a tensile storage modulus at 120 ° C. in the range of 10 MPa to 1000 MPa. In addition, from the viewpoint of improving the tensile storage modulus at 120 ° C. of the terminal resin film 16, one layer in the case of a single-layer structure may contain at least one selected from the group consisting of fillers and fibers. Good.

  When the terminal resin film 16 has a two-layer structure, the side in contact with the metal terminal 14 is the first outermost layer, and the side in contact with the packaging material 13 is the second outermost layer, and the first outermost layer is as described above. The first outermost layer 31 may have the same configuration, and the second outermost layer may have the same configuration as the second outermost layer 32 or the intermediate layer 33 described above. From the viewpoint of improving the tensile storage modulus at 120 ° C. of the terminal resin film 16, the second outermost layer in the case of the two-layer structure preferably has the same configuration as the above-described intermediate layer 33. From the viewpoint of improving the tensile storage modulus at 120 ° C. of the terminal resin film 16, the second outermost layer in the case of the two-layer structure contains at least one selected from the group consisting of fillers and fibers. May be.

  Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
<Preparation of tab>
With reference to FIG. 3, a method of manufacturing the tab (in other words, a structure including the metal terminal 14 (tab lead) and the pair of terminal resin films 16 (tab sealant)) of Example 1 will be described.

  First, an aluminum thin plate member having a width of 5 mm, a length of 20 mm, and a thickness of 100 μm was prepared as the metal terminal body 14-1. Next, a non-chromium surface treatment is performed on the surface of the aluminum thin plate member to form a corrosion prevention layer 14-2 (non-chromium surface treatment layer). The metal terminal 14 including the surface treatment layer was manufactured.

  Next, the terminal resin film 16 was produced as follows. In producing the terminal resin film 16, the first outermost layer was made of a random acid-modified polypropylene having a melting point of 140 ° C. (ethylene content: 4% by mass, weight average molecular weight (Mw): 160,000, MFR: 7 g / 10 min, anhydrous) A block type polypropylene having a melting point of 162 ° C. (having EPR and PE dispersed in homo PP in an island shape, PE content: 1% by mass, weight average molecular weight: 220,000, MFR: 1 g / 10 min), and a random acid-modified polypropylene having a melting point of 140 ° C., the same as that of the first outermost layer, was used for the second outermost layer.

  Next, a first outermost layer base material, an intermediate layer base material, and a second outermost layer base material are set in an inflation type film extrusion manufacturing apparatus (Co-OI type) manufactured by Sumitomo Heavy Industries Modern Co., Ltd. The three base materials were extruded by the film extrusion manufacturing apparatus to produce a laminated film (a film to be a base material of the terminal resin film 16). At this time, the laminated film was formed such that the thickness of the first outermost layer was 33 μm, the thickness of the intermediate layer was 34 μm, and the thickness of the second outermost layer was 33 μm. The melting temperature of the base material of the first outermost layer, the base material of the intermediate layer, and the base material of the second outermost layer was 210 ° C., and the blow ratio was 2.2.

  Next, by cutting the laminated film, a terminal resin film 16 having a width of 11 mm and a length of 5 mm was produced. About the produced resin film 16 for terminals, the tensile storage modulus at 25 ° C. and 120 ° C. and the heat absorption at the time of melting were measured. The tensile storage modulus is based on JIS K7244-4, and a test piece (thickness of each example and comparative example) obtained by cutting the terminal resin film 16 into a width of 10 mm and a length of 30 mm is a distance between chucks of 20 mm. And a value measured at a temperature of 120 ° C. and a frequency of 1 Hz using a dynamic viscoelasticity device (trade name: DMS6100, manufactured by SII). The endothermic amount at the time of melting was measured by a differential scanning calorimeter (trade name: DSC6220, manufactured by SII) from the area of the endothermic peak in the scanning temperature range of 10 ° C./min and the measurement temperature range of 80 ° C. to 170 ° C. It is a value obtained by dividing by the mass of the sample (resin film for terminal 16).

  Thereafter, the metal terminal 14 is sandwiched between the two terminal resin films 16, and the two terminal resin films 16 are heated and pressed at 200 ° C. and 0.3 MPa for 5 seconds to form the metal terminal 14 and the two terminal resin films. A tab made of the metal terminal 14 and the two terminal resin films 16 (width L of the protruding portion of the terminal resin film 16: 3 mm) was produced by heat-sealing the resin film 16 with the resin film 16. At this time, the terminal resin film 16 was arranged such that the first outermost layer was on the metal terminal 14 side.

(Example 2)
A tab was produced in the same manner as in Example 1 except that the thickness of the first outermost layer of the terminal resin film 16 was 25 μm, the thickness of the intermediate layer was 30 μm, and the thickness of the second outermost layer was 25 μm. did.

(Example 3)
A tab was produced in the same manner as in Example 2, except that the dimensions of the terminal resin film 16 were set to 15 mm in width and 5 mm in length, and the width L of the protruding portion of the terminal resin film 16 in the tab was set to 5 mm.

(Example 4)
Except that the intermediate layer of the terminal resin film 16 was changed to a 50 μm thick intermediate layer formed using a homopolypropylene having a melting point of 164 ° C. (weight average molecular weight: 260,000, MFR: 1.5 g / 10 min) as a base material. A tab was produced in the same manner as in Example 2.

(Example 5)
The first outermost layer of the terminal resin film 16 has a thickness of 25 μm, the second outermost layer has a thickness of 25 μm, and the intermediate layer has a thickness of 20 μm formed by using a crosslinked acrylic resin as a base material. A tab was produced in the same manner as in Example 1 except that the tab was changed to.

(Example 6)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 145 ° C. (ethylene content: 2.7% by mass, weight average molecular weight: 230,000, MFR: 3 g / 10 min, graft-modified with maleic anhydride). A tab was produced in the same manner as in Example 1 except that a single-layer structure consisting only of the first outermost layer having a thickness of 100 μm was formed.

(Example 7)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 143 ° C. (ethylene content: 2.9% by mass, weight-average molecular weight: 210,000, MFR: 1.5 g / 10 min, maleic anhydride graft-modified). A tab was produced in the same manner as in Example 1, except that the tab was a single-layer structure consisting of only the first outermost layer having a thickness of 55 μm and formed as a base material.

(Example 8)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 145 ° C. (ethylene content: 2.7% by mass, weight average molecular weight: 230,000, MFR: 3 g / 10 min, graft-modified with maleic anhydride). A first outermost layer having a thickness of 25 μm, a block type polypropylene having a melting point of 162 ° C. (weight average molecular weight: 260,000, MFR: 1 g / 10 min) 50% by mass, and a cellulose fiber (fiber width: 50 to 1000 nm) 50 A tab was produced in the same manner as in Example 1 except that a two-layer structure consisting of a second outermost layer having a thickness of 50 μm and formed using a base material composed of a mass% mixture was used.

(Example 9)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 145 ° C. (ethylene content: 2.7% by mass, weight average molecular weight: 230,000, MFR: 3 g / 10 min, graft-modified with maleic anhydride). A first outermost layer having a thickness of 25 μm and a second outermost layer having a thickness of 50 μm formed using a block type polypropylene having a melting point of 162 ° C. (weight average molecular weight: 260,000, MFR: 1 g / 10 min) as a base material. And a tab was produced in the same manner as in Example 1 except that the tab was formed.

(Example 10)
The terminal resin film 16 is formed using a random acid-modified polypropylene having a melting point of 140 ° C. (ethylene content: 4% by mass, weight average molecular weight: 130,000, MFR: 8 g / 10 min, maleic anhydride graft-modified) as a base material. A tab was produced in the same manner as in Example 1 except that the tab had a single-layer structure consisting of only the first outermost layer having a thickness of 55 μm.

(Example 11)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 140 ° C. (ethylene content: 3.9% by mass, weight-average molecular weight: 80,000, MFR: 10 g / 10 min, graft-modified with maleic anhydride). A tab was produced in the same manner as in Example 1 except that a single-layer structure consisting only of the 55 μm-thick first outermost layer was formed.

(Example 12)
The resin film 16 for the terminal is made of 95% by mass of a random acid-modified polypropylene having a melting point of 140 ° C. (ethylene content: 4% by mass, weight-average molecular weight: 130,000, MFR: 8 g / 10 min, maleic anhydride graft modified) A tab was produced in the same manner as in Example 1 except that a single-layer structure consisting only of the first outermost layer having a thickness of 55 μm was formed using a matrix consisting of a mixture of 5% by mass of silica particles having a particle diameter of 6 μm. did.

(Example 13)
The first outermost layer and the second outermost layer of the terminal resin film 16 were made of a random acid-modified polypropylene having a melting point of 140 ° C. (ethylene content: 3.9 mass%, weight average molecular weight: 80,000, MFR: 10 g / The first outermost layer and the second outermost layer having a thickness of 37.5 μm were formed by using a base material of maleic anhydride for 10 min, and the intermediate layer was made of polyethylene terephthalate having a melting point of 255 ° C. A tab was produced in the same manner as in Example 1 except that the thickness of the intermediate layer was changed to 25 μm.

(Comparative Example 1)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 138 ° C. (ethylene content: 4.2 mass%, weight average molecular weight: 220,000, MFR: 15 g / 10 min, maleic anhydride graft modified). A tab was produced in the same manner as in Example 1 except that a single-layer structure consisting only of the first outermost layer having a thickness of 100 μm was formed.

(Comparative Example 2)
Except that the terminal resin film 16 has a single-layer structure consisting of only a 80 μm-thick first outermost layer formed using polyethylene having a melting point of 115 ° C. (weight average molecular weight: 150,000, MFR: 24 g / 10 min) as a base material. A tab was produced in the same manner as in Example 1.

(Comparative Example 3)
50% by mass of a random acid-modified polypropylene having a melting point of 138 ° C. (ethylene content: 4.2% by mass, weight average molecular weight: 220,000, MFR: 15 g / 10 min, maleic anhydride grafted) having a melting point of 138 ° C. And a 100 μm-thick first material having a melting point of 110 ° C. and a 50% by mass of a mixture of acid-modified polyethylene (weight average molecular weight: 130,000, MFR: 18 g / 10 min, maleic anhydride graft-modified). A tab was produced in the same manner as in Example 1 except that the tab was a single-layer structure consisting of only the outermost layer.

(Comparative Example 4)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 138 ° C. (ethylene content: 4.2 mass%, weight average molecular weight: 220,000, MFR: 15 g / 10 min, maleic anhydride graft modified). A 100 μm thick first outermost layer and a random acid-modified polypropylene having a melting point of 138 ° C. (ethylene content: 4.2 mass%, weight average molecular weight: 220,000, MFR: 15 g / 10 min, maleic anhydride Was formed using a base material composed of a mixture of 50% by mass of an acid-modified polyethylene having a melting point of 110 ° C. (weight average molecular weight: 130,000, MFR: 18 g / 10 min, maleic anhydride grafted). A tab was produced in the same manner as in Example 1 except that the tab was a two-layer structure including a second outermost layer having a thickness of 50 μm.

(Comparative Example 5)
The first outermost layer and the second outermost layer of the terminal resin film 16 were made of a random acid-modified polypropylene having a melting point of 138 ° C. (ethylene content: 4.2 mass%, weight average molecular weight: 220,000, MFR: 15 g / The first outermost layer and the second outermost layer having a thickness of 30 μm were formed by using a base material of maleic anhydride for 10 min, and the intermediate layer was changed to a random polypropylene having a melting point of 140 ° C. (containing ethylene). (Amount: 4.1% by mass, weight-average molecular weight: 150,000, MFR: 15 g / 10 min) A tab was prepared in the same manner as in Example 1 except that the intermediate layer was changed to a 40 μm-thick intermediate layer. .

(Comparative Example 6)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 138 ° C. (ethylene content: 4.3 mass%, weight average molecular weight: 280,000, MFR: 2 g / 10 min, maleic anhydride graft-modified) 50 mass% A tab was formed in the same manner as in Example 1 except that a single-layer structure consisting only of the first outermost layer having a thickness of 100 μm was formed using a base material made of a mixture of 50% by mass of ethylene-propylene rubber as an elastomer. Produced.

(Comparative Example 7)
The terminal resin film 16 is made of a random acid-modified polypropylene having a melting point of 145 ° C. (ethylene content: 2.9% by mass, weight-average molecular weight: 200,000, MFR: 3 g / 10 min, graft-modified with maleic anhydride). A first outermost layer having a thickness of 20 μm, a block type polypropylene having a melting point of 162 ° C. (weight average molecular weight: 200,000, MFR: 1 g / 10 min) 20% by mass, and a cellulose fiber (fiber width: 50 to 1000 nm) 80 A tab was produced in the same manner as in Example 1 except that the tab was formed in a two-layer structure including a second outermost layer having a thickness of 80 μm and formed using a base material composed of a mass% mixture.

  Tables 1 and 2 collectively show the configurations of the terminal resin films 16 of Examples 1 to 13 and Comparative Examples 1 to 7, and the measurement results of the tensile storage modulus and the heat absorption. In the table, RPP represents random polypropylene, RPPa represents random acid-modified polypropylene, BPP represents block polypropylene, and HPP represents homopolypropylene. In addition, since the terminal resin film 16 of Comparative Example 2 was composed of only polyethylene (PE) having a melting point of 115 ° C., the tensile storage modulus at 120 ° C. could not be measured.

(Evaluation test for winding property)
The winding property of the terminal resin film 16 was evaluated by the following method. A long terminal resin film 16 (laminated film or single-layer film) having a width of 500 mm was produced in the same manner as in the examples and comparative examples, and was wound 300 m with a tension of 120 N around a 3-inch core. With respect to the terminal resin film 16 after winding, the presence or absence of breaks, wrinkles and cracks was visually observed. If no breaks, wrinkles and cracks were found and the film quality did not change, "A" , Wrinkles and cracks were evaluated as “B” when any one of them was confirmed. Table 3 shows the results.

(Evaluation test for dripping)
With respect to the tabs manufactured in the examples and the comparative examples, the sag of the terminal resin film 16 was evaluated by the following method. With respect to the tab immediately after the terminal resin film 16 is thermally fused to the metal terminal 14, the laminated portion of the metal terminal 14 and the terminal resin film 16 is placed on a table having a width approximately equal to the width of the metal terminal 14. It was supported by being mounted, and air-cooled at 25 ° C. for 10 minutes. As described above, by supporting the tab so that the protruding portion 16a is detached from the table, the protruding portion 16a can hang down to a position lower than the height of the table during cooling. After the air cooling, as shown in FIG. 4C, the amount of deformation D of the protruding portion 16a due to sagging (the difference in height between the upper end d1 and the lower end d2 of the lower surface of the deformed protruding portion 16a) was measured. Table 3 shows the results.

(Evaluation test for insulation properties)
<Preparation of battery pack for evaluation>
A 25 μm-thick nylon layer (outer layer 26), a 5 μm-thick polyester polyol-based adhesive (outer layer-side adhesive layer 25), and a 40 μm-thick aluminum foil (barrier layer 24) of A8079-O material; A first corrosion prevention treatment layer (corrosion prevention treatment layer 23-1) formed by treating one surface of the aluminum foil with a non-chromium surface treatment, and a first corrosion prevention treatment layer 23-1 formed by treating the other surface of the aluminum foil with a non-chromium treatment surface. A second corrosion prevention treatment layer (corrosion prevention treatment layer 23-2), an acid-modified polypropylene layer (inner side adhesive layer 22) having a thickness of 30 μm, a polypropylene layer (inner layer 21) having a thickness of 40 μm, And a packaging material 13 having a rectangular shape with a size of 50 mm × 90 mm was prepared.

  Next, the packaging material 13 is folded in two at the midpoint of the long side of the packaging material 13 and heat-sealed with one of the folded portions having a length of 45 mm sandwiching the tabs produced in Examples and Comparative Examples. And the tab were fused. At this time, as the conditions for the heat sealing, the heating temperature was 190 ° C. and the processing time was 5 seconds.

  Thereafter, the packaging material 13 was filled with 2 mL of an electrolyte obtained by adding lithium hexafluorophosphate to a mixed solution of diethyl carbonate and ethylene carbonate. Next, the remaining side of the packaging material 13 was heat-sealed. The conditions of the heat sealing at this time were a heating temperature of 190 ° C. and a processing time of 3 seconds. As a result, an evaluation battery pack in which the power storage device main body 11 is not sealed and which can perform tab evaluation was manufactured.

<Evaluation of insulation>
100 samples of the battery pack for evaluation were prepared, and the withstand voltage and insulation resistance tester (manufactured by Kikusui Electronics Co., Ltd., trade name: TOS9201) were used to connect the metal terminals 14 and the packaging material 13 constituting the battery pack for evaluation. The insulation between them was measured. The measurement of the insulating property was performed on the above 100 samples, and the number of samples in which short-circuit occurred was measured. Table 3 shows the results.

  As is clear from the results shown in Table 3, in Examples 1 to 13, the amount of deformation was reduced, no short circuit occurred, and the winding property was good. On the other hand, in Comparative Examples 1 to 6, the amount of deformation was large, and the occurrence of short circuits was large. In Comparative Example 7, the winding property was inferior.

DESCRIPTION OF SYMBOLS 10 ... Electric storage device, 11 ... Electric storage device main body, 13 ... Packaging material, 14 ... Metal terminal, 14-1 ... Metal terminal main body, 14-2 ... Corrosion prevention layer, 16 ... Terminal resin film, 16a ... Protruding part, 20 ... tab, 21 ... inner layer, 22 ... inner side adhesive layer, 23-1, 23-2 ... corrosion prevention treatment layer, 24 ... barrier layer, 25 ... outer side adhesive layer, 26 ... outer layer, 31 ... first Outermost layer, 32 ... second outermost layer, 33 ... intermediate layer.

Claims (12)

A terminal resin film for covering a part of the outer peripheral surface of the metal terminal constituting the power storage device,
Temperature 120 ° C. in a dynamic viscoelasticity measurement conforming to JIS K7244-4, Ri tensile storage modulus 10MPa~1000MPa der at a frequency of 1 Hz,
When the length of the protruding portion of the terminal resin film from the metal terminal when covering a part of the outer peripheral surface of the metal terminal is L , the terminal is used such that L is 1 to 5 mm. For resin film.   The terminal resin according to claim 1, wherein the terminal resin has a multilayer structure in which two or more layers are stacked, and includes, as at least one of the two or more layers, a heat-resistant layer containing a resin having a melting point of 200C or more. the film.   3. The terminal resin film according to claim 2, wherein the heat-resistant layer includes at least one selected from the group consisting of a polyester resin, a polycarbonate resin, a polyacetal resin, and a polyamide resin as the resin having a melting point of 200 ° C. or higher. 4.   The multilayered structure according to any one of claims 1 to 3, having a multilayer structure in which two or more layers are stacked, and including, as at least one of the two or more layers, a crosslinked layer containing a resin having a crosslinked structure. The resin film for terminals described in the above.   2. A multilayer structure in which two or more layers are stacked, and at least one of the two or more layers includes a reinforcing layer containing at least one selected from the group consisting of fillers and fibers. 5. The resin film for a terminal according to any one of items 4.   The multi-layer structure in which two or more layers are laminated, wherein at least one of the two or more layers includes a layer containing at least one selected from the group consisting of block polypropylene and homopolypropylene. The terminal resin film according to any one of claims 1 to 5.   An intermediate layer having a multilayer structure in which three or more layers are stacked, and including at least one selected from the group consisting of block polypropylene and homopolypropylene as at least one layer other than the outermost layer of the three or more layers. The terminal resin film according to any one of claims 1 to 6, which is provided.   The resin film for a terminal according to any one of claims 1 to 7, wherein an endothermic amount at the time of melting measured by a differential scanning calorimeter is 80 mJ / g or less.   The value of E1 / E2 is 1/20 or more in the dynamic viscoelasticity measurement, where the tensile storage modulus at 120 ° C. is E1, and the tensile storage modulus at 25 ° C. is E2. The resin film for a terminal according to any one of Items 1 to 8.   The terminal resin film according to any one of claims 1 to 9, which is formed by inflation molding. A metal terminal, comprising: a terminal resin film according to any one of claims 1 to 10, which is arranged to cover a part of an outer peripheral surface of the metal terminal ,
A tab , wherein L is 1 to 5 mm, where L is the length of the protruding portion of the terminal resin film from the metal terminal . Electricity storage device comprising a tab according to claim 1 1.

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