JP2015170428A - Insulating film for tab sealing and electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating film for tab sealing, by which a sealing state can be adequately maintained through the insulating film for sealing even when the internal pressure is raised.SOLUTION: An insulating film 1 for tab sealing comprises at least a base resin layer 2 including a resin composition which includes 70-99 mass% of an acid-modified polypropylene and 1-30 mass% of a thermoplastic elastomer. The resin composition has a melting point of 155°C or higher, of which MFR is 10 g per 10 minutes or less.

Description

  The present invention relates to an insulating film for sealing a tab used in an electrochemical device such as a lithium ion secondary battery and an electric double layer capacitor, and an electrochemical device configured using the insulating film.

  In the present specification, the term “MFR” means MFR (melt flow rate) measured under conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210-1999.

  Further, in this specification, the term “melting point” was measured at a rate of temperature increase of 10 ° C./min using a differential scanning calorimeter according to the method defined in JIS K7121-1987 “Method for Measuring Plastic Transition Temperature”. It means melting peak temperature (melting point).

  A laminate type electrochemical device used as a thin battery has a power generation element including an electrode and an electrolyte housed in a packaging outer film, and a part of a lead terminal connected to the power generation element is pulled out to the outside. The outer peripheral film has a structure in which the power generation element is sealed by heat-sealing the peripheral edge of the outer film.

  The pair of lead terminals in the electrochemical device may break through the inner surface layer of the exterior film at the time of the heat sealing, and contact with the metal foil of the intermediate layer to cause a short circuit.

  Therefore, in order to prevent such a short circuit, a position corresponding to the seal portion of the exterior film in the lead terminal is covered with a sealing insulating film. Specifically, it has been proposed that portions corresponding to the seal portions in the positive electrode lead terminal and the negative electrode lead terminal are previously covered with a sealing film made of a heat-adhesive synthetic resin having an insulating property (Patent Literature). 1-4).

JP 2008-192451 A JP 2003-007265 A JP 2010-245000 A JP 2009-224218 A

  By the way, in the case of a lithium ion secondary battery or the like, gas is likely to be generated in the battery body during overcharge or overheating, and for this reason, the gas gradually accumulates in the internal space covered with the exterior material. Internal internal pressure may increase. However, in the conventional sealing insulating film, when the internal pressure is increased as described above, the sealing state of the lead terminal cannot always maintain a sufficient sealing state.

  The present invention has been made in view of such a technical background, and an insulating film for tab sealing and an electric device that can sufficiently maintain a sealing state via the insulating film for sealing even when the internal pressure increases. The object is to provide a chemical device.

  In order to achieve the above object, the present invention provides the following means.

[1] At least a base resin layer made of a resin composition comprising 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer,
An insulating film for tab sealing, wherein the resin composition has a melting point of 155 ° C. or higher, and the MFR of the resin composition is 10 g / 10 min or less.

[2] From a resin composition comprising 70% by mass to 99% by mass of a first resin component made of acid-modified polypropylene and polypropylene not modified with acid, and 1% by mass to 30% by mass of a thermoplastic elastomer. Comprising at least a base resin layer,
An insulating film for tab sealing, wherein the resin composition has a melting point of 155 ° C. or higher, and the MFR of the resin composition is 10 g / 10 min or less.

  [3] The insulating film has a configuration in which an outer resin layer is laminated on a surface of the base resin layer on an exterior material side, and an inner resin layer is laminated on a tab side surface of the base resin layer, The insulating film for tab sealing according to the preceding item 1 or 2, wherein the outer resin layer contains acid-modified polypropylene or / and polypropylene not modified with acid, and the inner resin layer contains acid-modified polypropylene.

[4] The melting point of the outer resin layer is 130 ° C to 140 ° C, the melting point of the inner resin layer is 130 ° C to 140 ° C,
4. The tab sealing insulating film according to item 3, wherein the melting point of the base resin layer is 25 ° C. or more higher than the melting point of the outer resin layer and 25 ° C. or more higher than the melting point of the inner resin layer.

  [5] The insulating film for tab sealing according to item 4, wherein the melting point of the base resin layer is 25 ° C. to 45 ° C. higher than the melting point of the outer resin layer and 25 ° C. to 45 ° C. higher than the melting point of the inner resin layer. .

[6] The insulating film has a configuration in which an outer resin layer is laminated on a surface of the base resin layer on an exterior material side and an inner resin layer is laminated on a tab side surface of the base resin layer,
The outer resin layer comprises a resin composition having a melting point of less than 155 ° C., comprising 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer,
The preceding item 1 or 2 wherein the inner resin layer comprises a resin composition having a melting point of less than 155 ° C., comprising 70% to 99% by mass of acid-modified polypropylene and 1% to 30% by mass of a thermoplastic elastomer. 2. Insulating film for sealing tabs.

[7] The insulating film has a configuration in which an outer resin layer is laminated on a surface on the exterior material side of the base resin layer, and an inner resin layer is laminated on a tab side surface of the base resin layer,
Melting | fusing point formed by the said outer side resin layer containing 70 mass%-99 mass% of 1st resin components which consist of acid-modified polypropylene and the polypropylene which is not modified | denatured with acid, and 1 mass%-30 mass% of thermoplastic elastomers. Consists of a resin composition of less than 155 ° C,
Melting | fusing point formed by the said inner side resin layer containing 70 mass%-99 mass% of 1st resin components which consist of acid-modified polypropylene and the polypropylene which is not modified | denatured with an acid, and thermoplastic elastomer 1 mass%-30 mass%. The insulating film for tab sealing according to 1 or 2 above, comprising a resin composition having a temperature of less than 155 ° C.

  [8] The insulating film for tab sealing according to any one of items 1 to 7, wherein the thermoplastic elastomer has a melting point of 80 ° C. or lower and the thermoplastic elastomer has an MFR of 5 g / 10 min or less.

  [9] The tab sealing according to any one of items 1 to 8, wherein the thermoplastic elastomer is one or two resins selected from the group consisting of ethylene-propylene rubber and ethylene-propylene-butene rubber. Insulating film.

  [10] An electrochemical device comprising the tab sealing insulating film described in any one of 1 to 9 above.

[11] an exterior material;
An electrochemical element housed in the exterior material;
An inner end portion is electrically connected to the electrochemical element, and an outer end portion is disposed outside the exterior material, and a tab,
The both sides of the tab are sandwiched between the tab sealing insulating films according to any one of the preceding items 1 to 9 by the seal portion of the exterior material, and the seal portion of the exterior material is placed on both sides of the tab. An electrochemical device characterized by being bonded.

  In the invention of [1], at least a base resin layer comprising a resin composition comprising 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer is included. The base resin layer contains acid-modified polypropylene at a content within the above specified range, thereby ensuring adhesive strength (adhesive strength with respect to the metal tab and exterior material) and thermoplasticity at the above specified range. By containing an elastomer, it is possible to prevent the occurrence of cohesive failure inside the base resin layer even when stress is concentrated on the thermoplastic elastomer component when force is applied to the tab sealing insulating film due to an increase in internal pressure, etc. The good sealing state through the tab sealing insulating film can be sufficiently maintained.

  Further, since the melting point of the base resin layer is 155 ° C. or higher, the base resin layer is not easily crushed at the time of seal bonding, thereby ensuring sufficient insulation. Furthermore, since the MFR of the resin composition is 10 g / 10 min or less, the base resin layer is not easily crushed at the time of seal bonding, and there is an advantage that more sufficient insulation can be secured.

  In invention of [2], it contains 70 mass%-99 mass% of 1st resin components which consist of acid-modified polypropylene and polypropylene which is not modified with acid, and thermoplastic elastomer 1 mass%-30 mass%. It is the structure containing at least the base resin layer which consists of a resin composition, and an adhesive force (adhesive strength with respect to a metal tab, and adhesive strength with respect to an exterior material) is included because a base resin layer contains a 1st resin component with the content rate of the said specific range. ) Can be secured, and when the thermoplastic elastomer is contained in the specified range, the stress is concentrated on the thermoplastic elastomer component when a force is applied to the tab sealing insulating film due to an increase in internal pressure or the like. However, the occurrence of cohesive failure within the base resin layer can be prevented, and a good sealing state via the tab sealing insulating film can be sufficiently maintained.

  Further, since the melting point of the base resin layer is 155 ° C. or higher, the base resin layer is not easily crushed at the time of seal bonding, thereby ensuring sufficient insulation. Furthermore, since the MFR of the resin composition is 10 g / 10 min or less, the base resin layer is not easily crushed at the time of seal bonding, and there is an advantage that more sufficient insulation can be secured.

  In the invention of [3], since the outer resin layer laminated on the surface of the base resin layer on the exterior material side contains acid-modified polypropylene and / or polypropylene not modified with acid, the outer resin layer Can be sufficiently sealed and bonded to the exterior material at a low temperature, and the inner resin layer laminated on the tab side surface of the base resin layer has a structure containing acid-modified polypropylene. The layer can be sufficiently thermally bonded to the metal tab. In this configuration, since the base resin layer of the intermediate layer has a melting point of 155 ° C. or higher, the base resin layer is not easily crushed at the time of seal bonding, thereby ensuring sufficient insulation.

  In the invention of [4], the melting point of the outer resin layer is 130 ° C to 140 ° C, the melting point of the inner resin layer is 130 ° C to 140 ° C, and the melting point of the base resin layer is 25 ° C higher than the melting point of the outer resin layer. Since it is higher than the above and 25 ° C. higher than the melting point of the inner resin layer, it is possible to ensure sufficient seal bonding strength and sufficient insulation (both sufficient sealability and sufficient insulation can be ensured).

  In the invention of [5], the melting point of the base resin layer is 25 ° C. to 45 ° C. higher than the melting point of the outer resin layer and 25 ° C. to 45 ° C. higher than the melting point of the inner resin layer. Since it is below ℃, there is an advantage that more sufficient sealing performance (sealing performance) and more sufficient insulation can be secured.

  In the inventions [6] and [7], the outer resin layer laminated on the surface of the base resin layer on the exterior material side is 70% to 99% by mass of acid-modified polypropylene and 1% to 30% by mass of a thermoplastic elastomer. %, And the melting point of the resin composition is less than 155 ° C., the outer resin layer can be sufficiently sealed and bonded to the exterior material, and the tab side of the base resin layer From the resin composition having a melting point of less than 155 ° C., wherein the inner resin layer laminated on the surface of the resin comprises 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer. Therefore, the inner resin layer can be sufficiently thermally bonded to the metal tab. Furthermore, since all of the base resin layer, the outer resin layer, and the inner resin layer contain 1% by mass to 30% by mass of the thermoplastic elastomer, the entire insulating film for tab sealing is given flexibility and is bent. Whitening can be reduced.

  In the invention of [8], since the melting point of the thermoplastic elastomer is 80 ° C. or less, the adhesive force to the metal tab can be further improved. Further, since the MFR of the thermoplastic elastomer is 5 g / 10 min or less, the thermoplastic elastomer in the acid-modified polypropylene (or the first resin component) in the base resin layer has an independent size of about 0.3 μm to about 15 μm. The spherical dispersed phase is formed, and there is an advantage that sufficient sealing strength can be secured even in an incompatible resin composition.

  In the invention of [9], since the thermoplastic elastomer is one or two resins selected from the group consisting of ethylene-propylene rubber and ethylene-propylene-butene rubber, an insulating film for tab sealing due to an increase in internal pressure or the like Even if a force is applied to the resin, the thermoplastic elastomer component can sufficiently absorb the stress and prevent the occurrence of cohesive failure inside the base resin layer. The satisfactory sealed state can be maintained more sufficiently.

  In the inventions [10] and [11] (electrochemical devices), even when stress is concentrated on the thermoplastic elastomer component when a force is applied to the tab sealing insulating film due to an increase in internal pressure or the like, The occurrence of cohesive failure can be prevented, and a good sealing state via the tab sealing insulating film can be sufficiently maintained. In addition, since the melting point of the base resin layer of the tab sealing insulating film is 155 ° C. or higher, the base resin layer is not easily crushed during seal bonding, thereby ensuring sufficient insulation. Further, since the MFR of the base resin layer of the tab sealing insulating film is 10 g / 10 min or less, the base resin layer is not easily crushed at the time of seal bonding, and there is an advantage that more sufficient insulation can be secured.

It is sectional drawing which shows one Embodiment of the insulating film for tab sealing which concerns on this invention. It is a perspective view which shows the state which accommodated the electrochemical element in the exterior material processed into the bag shape. It is sectional drawing (sectional drawing in a seal part) which shows one Embodiment of the electrochemical device comprised using the insulating film for tab sealing which concerns on this invention. 3 is a graph showing an SD curve in the measurement of the sealing strength of the tab sealing insulating film obtained in Example 1. FIG. It is a graph which shows the SD curve in the sealing strength measurement of the insulating film for tab sealing obtained in the comparative example 1.

  The insulating film 1 for tab sealing according to the present invention is a base resin layer made of a resin composition containing 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer. 2, the melting point of the resin composition is 155 ° C. or more, and the MFR of the resin composition is 10 g / 10 min or less.

  Moreover, the insulating film 1 for tab sealing which concerns on this invention is 70 mass%-99 mass% of 1st resin components which consist of acid-modified polypropylene and the polypropylene which is not modified | denatured with acid, and 1 mass%-30 mass of thermoplastic elastomers. %, And the resin composition has a melting point of 155 ° C. or higher, and the MFR of the resin composition is 10 g / 10 min or less. It is what.

  In the present invention, the base resin layer 2 contains 70% by mass to 99% by mass of the first resin component containing 70% by mass to 99% by mass of acid-modified polypropylene, or acid-modified polypropylene and polypropylene not modified with acid. Since the composition contains 1% by mass to 30% by mass, the adhesive strength (adhesive strength to the metal tab and the adhesive strength to the exterior material) can be ensured, and the thermoplastic elastomer is contained in an amount of 1 to 30% by mass. When force is applied to the tab sealing insulating film by the above, even if stress is concentrated in the acid-modified polypropylene or the thermoplastic elastomer component dispersed in the first resin component, the cohesive failure in the base resin layer 2 is caused. Generation | occurrence | production can be prevented and the favorable sealing state through the insulating film 1 for tab sealing can fully be maintained.

  In the present invention, usually, the thermoplastic elastomer forms a phase separation structure in the acid-modified polypropylene, or the thermoplastic elastomer forms a phase separation structure in the first resin component, and the dispersion When stress is concentrated on the thermoplastic elastomer component, it is possible to prevent the stress from sequentially propagating through the thermoplastic elastomer phase of the phase separation structure as much as possible, thereby preventing the occurrence of cohesive failure inside the base resin layer 2. The insulating film 1 for sealing which can prevent more fully and has the stable sealing strength can be provided.

  In the phase separation structure, there are those in which the thermoplastic elastomer phase is phase-separated in a substantially plate shape, and it is possible to suppress the propagation of stress in order between the adjacent substantially plate-like thermoplastic elastomer phases. It is estimated that the occurrence of cohesive failure can be prevented. The substantially plate-like thermoplastic elastomer phase is considered to be spread substantially parallel to the surface of the sealing insulating film 1.

  In addition, since the melting point of the resin composition (base resin layer 2) is 155 ° C. or higher, the base resin layer 2 is not easily crushed at the time of seal bonding, thereby ensuring sufficient insulation. The melting point of the resin composition (base resin layer 2) is preferably in the range of 155 ° C to 175 ° C.

  Furthermore, since the MFR of the resin composition (base resin layer 2) is 10 g / 10 min or less, the base resin layer 2 is not easily crushed during seal bonding, and sufficient insulation can be secured. The MFR of the resin composition (base resin layer 2) is preferably in the range of 0.2 g / 10 min to 10 g / 10 min. The sealing property can be improved by being 0.2 g / 10 min or more. Especially, it is especially preferable that MFR of the said resin composition (base resin layer 2) is the range of 0.5g / 10min-7g / 10min.

  When the content of the thermoplastic elastomer in the base resin layer exceeds 30% by mass, when a force is applied to the tab sealing insulating film due to an increase in internal pressure or the like, a good condition is obtained via the tab sealing insulating film. The sealed state cannot be ensured. In addition, when the content of the thermoplastic elastomer in the base resin layer is less than 1% by mass, the effect of the thermoplastic elastomer component cannot be sufficiently obtained, so that force is applied to the tab sealing insulating film due to an increase in internal pressure or the like. Sometimes, adhesiveness with a tab metal becomes low, and a favorable sealing state via the insulating film for tab sealing cannot be secured. The content of the thermoplastic elastomer in the base resin layer 2 is preferably in the range of 5% by mass to 25% by mass.

  The tab sealing insulating film 1 according to the present invention has a configuration including at least the base resin layer 2 having the specific configuration described above, and includes only the base resin layer 2 having the specific configuration (a single layer of the base resin layer 2). There may be a laminated structure in which a resin layer is laminated on at least one surface of the base resin layer 2 having the specific structure.

  As the latter laminated structure, as shown in FIGS. 1 and 3, the outer resin layer 3 is laminated on the surface of the base resin layer 2 on the exterior material 23 side, and the tab 21 (22) in the base resin layer 2 is laminated. The inner resin layer 4 is laminated on the side surface, and the outer resin layer 3 contains “acid-modified polypropylene” and / or “polypropylene not modified with acid”, and the inner resin layer 4 It is preferable to adopt a configuration containing acid-modified polypropylene.

  In the above configuration, the melting point of the outer resin layer is 130 ° C. to 140 ° C., the melting point of the inner resin layer is 130 ° C. to 140 ° C., and the melting point of the base resin layer 2 is 25 ° C. or more than the melting point of the outer resin layer 3. When the structure is high and 25 ° C. or more higher than the melting point of the inner resin layer 4, sufficient seal bonding strength can be secured and sufficient insulation can be secured (that is, sufficient sealability and sufficient insulation). Can ensure both).

  Further, the melting point of the base resin layer 2 is preferably 25 ° C. to 45 ° C. higher than the melting point of the outer resin layer 3 and 25 ° C. to 45 ° C. higher than the melting point of the inner resin layer 4. By being 45 degrees C or less, more sufficient sealing performance (sealing property) and more sufficient insulation can be ensured.

  Alternatively, the following configuration may be adopted as the stacked configuration. That is, as shown in FIGS. 1 and 3, the outer resin layer 3 is laminated on the surface of the base resin layer 2 on the exterior material 23 side, and the inner surface of the base resin layer 2 on the tab 21 (22) side surface. The resin layer 4 is laminated, and the outer resin layer 3 has a melting point formed by containing 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer. It consists of a resin composition of less than 155 ° C., and the inner resin layer 4 contains 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer, and has a melting point of 155 ° C. The structure which consists of less resin compositions may be sufficient.

  Alternatively, as shown in FIGS. 1 and 3, the outer resin layer 3 is laminated on the surface of the base resin layer 2 on the exterior material 23 side, and on the surface of the base resin layer 2 on the tab 21 (22) side. The inner resin layer 4 is laminated, and the outer resin layer 3 is composed of 70% by mass to 99% by mass of a first resin component composed of “acid-modified polypropylene” and “polypropylene not modified with acid”, A thermoplastic elastomer containing 1% by mass to 30% by mass, and a resin composition having a melting point of less than 155 ° C., wherein the inner resin layer 4 is “acid-modified polypropylene” and “polypropylene not modified with acid” And a resin composition having a melting point of less than 155 ° C., comprising 70% by mass to 99% by mass of the first resin component and 1% by mass to 30% by mass of the thermoplastic elastomer. It may be.

  In the present invention, the acid-modified polypropylene is not particularly limited, and examples thereof include carboxylic acid-modified polypropylene. The carboxylic acid-modified polypropylene is not particularly limited. For example, maleic acid-modified polypropylene, maleic anhydride-modified polypropylene, itaconic anhydride-modified polypropylene, itaconic acid-modified polypropylene, acrylic acid-modified polypropylene, methacrylic acid-modified Examples thereof include polypropylene, fumaric acid-modified polypropylene, and citraconic acid-modified polypropylene. Among these, as the acid-modified polypropylene, it is preferable to use at least one acid-modified polypropylene selected from the group consisting of maleic acid-modified polypropylene, maleic anhydride-modified polypropylene, and acrylic acid-modified polypropylene.

  Although it does not specifically limit as said thermoplastic elastomer, For example, an olefin type thermoplastic elastomer, a styrene-type elastomer, a hydrogenated styrene-type elastomer etc. are mentioned.

  Although it does not specifically limit as said olefin type thermoplastic elastomer, For example, an ethylene-alpha-olefin copolymer etc. are mentioned. Examples of the α-olefin include propylene, 1-butene, 1-hexane and the like.

  The styrene-based elastomer and hydrogenated styrene-based elastomer are not particularly limited. For example, styrene-ethylene / butylene-styrene copolymer, styrene-ethylene / propylene-styrene copolymer, styrene-ethylene / Examples include butylene-styrene hydrogenated copolymer and styrene-ethylene / propylene-styrene hydrogenated copolymer.

  Among them, it is preferable to use one or two thermoplastic elastomers selected from the group consisting of ethylene-propylene rubber (EPR) and ethylene-propylene-butene rubber (EPBR) as the thermoplastic elastomer. Examples of the EPBR include ethylene-propylene-1-butene rubber.

  The thermoplastic elastomer preferably has a melting point of 80 ° C. or lower. By using a thermoplastic elastomer having a melting point of 80 ° C. or less, there is an advantage that sufficient adhesion with the surface of the tab can be ensured during heat seal bonding.

  The thermoplastic elastomer preferably has an MFR of 5 g / 10 min or less. By using a thermoplastic elastomer having an MFR of 5 g / 10 min or less, the base elastomer layer 2 has an independent amount of about 0.3 μm to about 15 μm in the thermoplastic elastomer in the acid-modified polypropylene (or the first resin component). Thus, there is an advantage that sufficient sealing strength can be secured even in an incompatible resin composition.

  The “polypropylene not modified with acid” is not particularly limited, but one or two resins selected from the group consisting of homopolypropylene and random polypropylene (ethylene-propylene random copolymer) are used. It is preferable to use it. The propylene content in the ethylene-propylene random copolymer is preferably in the range of 85% by mass to 99% by mass.

  In the first resin component (first resin component made of acid-modified polypropylene and polypropylene not modified with acid), the content of acid-modified polypropylene is preferably set in the range of 1% by mass to 99% by mass. . Among them, the content of the acid-modified polypropylene in the first resin component is more preferably set in the range of 1% by mass to 50% by mass, and in this case, the cost can be reduced and it is economical.

  In the present invention, the thickness of the base resin layer 2 is preferably set to 20 μm to 70 μm. Moreover, it is preferable that the thickness of the outer resin layer 3 is set to 15 μm to 40 μm. Moreover, it is preferable that the thickness of the inner resin layer 4 is set to 15 μm to 40 μm.

  Moreover, it is preferable that the thickness of the insulating film 1 for tab sealing of this invention is set to 50 micrometers-150 micrometers.

  FIG. 3 shows an embodiment of an electrochemical device 20 configured using the tab sealing insulating film 1 of the present invention. The electrochemical device 20 includes an electrochemical element, electrode tabs 21 and 22, a tab sealing insulating film 1, and an exterior material 23.

  An example of the manufacturing procedure of the electrochemical device 20 will be described. First, as shown in FIG. 2, the outer packaging materials (exterior films) 23 and 23 cut into two squares are opposed to each other with their inner surfaces facing each other, and the surrounding three sides 23a, 23b and 23c are thermally welded to form a bag. Create a shape.

Further, as shown in FIG. 2, the tab sealing insulating films 1, 1 are welded to the portion corresponding to the seal portion 23 d in the positive electrode tab 21 while being sandwiched from both sides, and correspond to the seal portion 23 d in the negative electrode tab 22. The tab sealing insulating films 1 and 1 are welded in a state of being sandwiched from both sides. These tabs 21 and 22 are joined and fixed to the electrochemical element by welding. The positive electrode tab 21 is made of a metal conductor such as aluminum or titanium. The negative electrode tab 22 is made of, for example, a metal conductor such as copper, nickel, or nickel-plated copper. In addition, the said electrochemical element is comprised by laminating | stacking the positive electrode and the negative electrode through the electrolyte part. As the tab material (the material of the tabs 21 and 22), it is preferable to use a rolled hard foil or plate. Moreover, in order to prevent corrosion of the metal surfaces constituting the tabs 21 and 22 and to ensure sufficient adhesion to the tab sealing insulating film 1, the tabs 21 and 22 may be subjected to a ground treatment. For example, in the case of chromate treatment, the aqueous solution of any one of 1) to 3) below is applied to the surface of the metal material that has been degreased and then dried.
1) Aqueous solution comprising a mixture of phosphoric acid, chromic acid and fluoride metal salt 2) Aqueous solution comprising a mixture of phosphoric acid, chromic acid and fluoride non-metal salt 3) Consisting of acrylic resin, chitosan derivative resin and phenolic resin An aqueous solution comprising a mixture of at least one resin selected from the group, phosphoric acid, chromic acid (or chromium (III) salt), and a fluoride metal salt.

  Next, the electrochemical element to which the tabs 21 and 22 are connected is accommodated in the bag-like material. Next, the entire areas of the seal portions 23d and 23d are thermally welded to each other in a state where the tabs 21 and 22 are sandwiched between the tab sealing insulating films 1 and 1 by the bag-like seal portions 23d and 23d (FIG. 2). 3). Thereby, the electrochemical device (battery etc.) 20 by which the electrochemical element was accommodated in the exterior material (exterior film) 23 and 23 in the airtight state is produced. In this electrochemical device 20, the front end portion 21b of the positive electrode tab 21 and the front end portion 22b of the negative electrode tab 22 are led out of the exterior material 23 (see FIG. 2).

  In addition, the electrochemical device 20 of this invention is not specifically limited to what is obtained with the said manufacturing method.

  Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Raw materials>
(Resin composition A)
60 parts by mass of maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.2% by mass) and 40 parts by mass of ethylene-propylene rubber (EPR, “Tuffmer P-0480” manufactured by Mitsui Chemicals, Inc.) using a twin screw extruder A resin composition obtained by melt-kneading at a resin temperature of 230 ° C. The MFR of the resin composition A is 1.3 g / 10 minutes, and the melting point of the resin composition A is 168 ° C.
(Resin composition B)
Obtained by melt-kneading 85 parts by mass of maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.2 mass%) and 15 parts by mass of ethylene-propylene rubber (EPR) at a resin temperature of 230 ° C. with a twin screw extruder. Resin composition. The MFR of the resin composition B is 6 g / 10 minutes, and the melting point of the resin composition B is 168 ° C.
(Resin composition C)
Obtained by melt-kneading 70 parts by mass of maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.2% by mass) and 30 parts by mass of ethylene-propylene rubber (EPR) at a resin temperature of 230 ° C. with a twin screw extruder. Resin composition. The MFR of the resin composition C is 3.5 g / 10 minutes, and the melting point of the resin composition C is 168 ° C.
(Resin composition D)
10 parts by mass of maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.3% by mass), 89 parts by mass of homopolypropylene resin (MFR: 0.4 g / 10 min), 1 part by mass of ethylene-propylene rubber (EPR) A resin composition obtained by melt-kneading at a resin temperature of 230 ° C. with a twin-screw extruder. The MFR of the resin composition D is 0.5 g / 10 minutes, and the melting point of the resin composition D is 165 ° C.
(Resin composition E)
15 parts by mass of maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.3% by mass), 83 parts by mass of homopolypropylene resin (MFR: 0.4 g / 10 min), 2 parts by mass of ethylene-propylene rubber (EPR) A resin composition obtained by melt-kneading at a resin temperature of 230 ° C. with a twin-screw extruder. The MFR of the resin composition E is 0.5 g / 10 minutes, and the melting point of the resin composition E is 163 ° C.
(Resin composition F)
It is obtained by melt-kneading 75 parts by mass of maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.2% by mass) and 25 parts by mass of ethylene-propylene rubber (EPR) at a resin temperature of 230 ° C. with a twin screw extruder. Resin composition. The MFR of the resin composition F is 3.2 g / 10 minutes, and the melting point of the resin composition F is 134 ° C.
(Resin G)
Maleic anhydride-modified polypropylene resin (maleic anhydride graft amount 0.2 mass%). The MFR of the resin G is 3.5 g / 10 minutes, and the melting point of the resin G is 134 ° C.
(Resin H)
Random polypropylene resin (ethylene-propylene random copolymer; propylene content 4% by mass). The MFR of this resin H is 3 g / 10 min, and the melting point of the resin H is 140 ° C.

  In addition, said "MFR" means MFR (melt flow rate) measured on condition of temperature 230 degreeC and load 2.16kg based on JISK7210-1999.

  The “melting point” is raised using a DSC (Differential Scanning Calorimeter) (model DSC-60A) manufactured by Shimadzu Corporation in accordance with “Measurement Method of Plastic Transition Temperature” of JIS K7121-1987. It is a melting peak temperature (melting point) obtained from a DSC curve obtained by measurement at a rate of 10 ° C./min.

<Example 1>
The resin composition B was extruded from an extruder to obtain an insulating film for tab sealing having a thickness of 80 μm.

<Example 2>
Resin composition C was extruded from an extruder to obtain an insulating film for tab sealing having a thickness of 80 μm.

<Example 3>
Resin composition D was extruded from an extruder to obtain an insulating film for tab sealing having a thickness of 80 μm.

<Example 4>
The resin composition E was extruded from an extruder to obtain an insulating film for tab sealing having a thickness of 80 μm.

<Comparative Example 1>
Resin composition A was extruded from an extruder to obtain an insulating film for tab sealing having a thickness of 80 μm.

<Example 5>
An outer resin layer 3 made of resin composition F having a thickness of 30 μm is laminated on one surface of a base resin layer 2 made of resin composition B and having a thickness of 40 μm, and a resin composition is made on the other surface of the base resin layer 2. The tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 made of the product F and having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

<Example 6>
An outer resin layer 3 made of resin composition F and having a thickness of 30 μm is laminated on one surface of a base resin layer 2 made of resin composition C and having a thickness of 40 μm, and a resin composition is formed on the other surface of the base resin layer 2. The tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 made of the product F and having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

<Example 7>
An outer resin layer 3 having a thickness of 30 μm made of a resin composition F is laminated on one surface of a base resin layer 2 made of a resin composition D and having a thickness of 40 μm, and a resin composition is formed on the other surface of the base resin layer 2. The tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 made of the product F and having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

<Example 8>
An outer resin layer 3 having a thickness of 30 μm made of a resin composition F is laminated on one surface of a base resin layer 2 made of a resin composition E and having a thickness of 40 μm, and a resin composition is formed on the other surface of the base resin layer 2. The tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 made of the product F and having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

<Comparative Example 2>
An outer resin layer 3 having a thickness of 30 μm made of resin composition F is laminated on one surface of a base resin layer 2 made of resin composition A and having a thickness of 40 μm, and a resin composition is formed on the other surface of base resin layer 2. The tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 made of the product F and having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

<Example 9>
An outer resin layer 3 made of resin G having a thickness of 30 μm is laminated on one surface of a base resin layer 2 made of resin composition C and having a thickness of 40 μm, and made of resin G on the other surface of the base resin layer 2. A tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

<Example 10>
An outer resin layer 3 made of resin H and having a thickness of 30 μm is laminated on one surface of a base resin layer 2 made of resin composition B and having a thickness of 40 μm, and a resin G is made on the other surface of the base resin layer 2. A tab sealing insulating film 1 shown in FIG. 1 having a structure in which an inner resin layer 4 having a thickness of 30 μm was laminated was obtained by a coextrusion inflation molding method.

  Each tab sealing insulating film obtained as described above was evaluated based on the following evaluation method. These results are shown in Tables 1-3.

<Evaluation method of sealing performance by measuring seal strength>
The surface of the inner resin layer of the obtained tab sealing insulating film is overlaid on the surface of the tab lead material (tab), and the surface of the inner layer of the exterior material is overlaid on the surface of the outer resin layer of the insulating film. By heating at 200 ° C., the tab lead material (tab) / tab sealing insulating film / exterior material was sealed and bonded to obtain a sealed bonded product. In addition, the exterior material is obtained by dry laminating a 25 μm thick biaxially stretched polyamide film on one surface of an aluminum foil having a thickness of 40 μm, and an unstretched polypropylene film having a thickness of 40 μm on the other surface of the aluminum foil (inside It is an exterior material obtained by dry laminating a layer. In addition, the tab lead material (tab) is a surface of a copper plate having a thickness of 0.3 mm, a width of 60 mm, and a length of 50 mm, which is plated with nickel of 2 μm, and further an aqueous solution containing chitosan resin, chromium fluoride and phosphoric acid. It is obtained by processing.

Next, the seal bonded product was cut in the length direction to cut out a test body having a width of 15 mm and a length of 150 mm. Next, in accordance with JIS Z0238-1998, both the exterior material of this specimen and the insulating film for sealing the tab are chucked by the upper chuck portion of the strograph manufactured by Toyo Seiki Co., Ltd., and the tab lead material is lowered by the lower chuck portion. The peel strength at the time of chucking and peeling at 180 ° at a tensile speed of 10 mm / min was measured, and this was defined as the seal strength (N / 15 mm width) between the tab lead material and the tab sealing insulating film. At this time, S (Seal-Strength)-where the vertical axis is the seal strength (N / 15 mm width), and the horizontal axis is the elongation (displacement of the tab sealing insulating film; distance moved between chucks) (mm) A D (Distance) curve was recorded, and the sealing performance (sealing strength) of the insulating film for tab sealing was evaluated from the SD curve based on the following criteria.
(Criteria)
“◯”: In the SD curve, no decrease in seal strength was observed after the first yield point, and a seal strength of 50 (N / 15 mm width) or greater was obtained after the first yield point (this evaluation). Was obtained)
“△”: In the SD curve, a significant decrease in seal strength is observed after the first yield point, but a seal strength of 50 (N / 15 mm width) or more is obtained after the first yield point. In the SD curve, a significant decrease in the seal strength is recognized after the first yield point, and the seal strength is less than 50 (N / 15 mm width) after the first yield point.

<Evaluation method of sealing performance by observation of peeling interface>
While visually examining the color of the peel interface after performing the 180 degree peel test, the cross section of the peel interface is observed with a SEM (scanning electron microscope) to examine the peel position (where the peel is). Based on the following criteria, the sealing performance (sealing strength) of the tab sealing insulating film was evaluated. In the color of the peeling interface, the white part indicates that cohesive failure occurs inside the layer, and the gray part indicates that cohesive failure occurs at the interface between the resin layer and the resin layer. It is.
(Criteria)
“◯”: The color of the peeling interface includes a white part and a gray part, and the peeling position is the interface between the base resin layer and the outer resin layer or the interface between the base resin layer and the inner resin layer (near the resin layer) Cohesive failure has occurred) (This "○" evaluation was accepted)
“X”: The color of the peeling interface is white on the entire surface, and the peeling position is not in the resin layer (interface between the resin layers) but in the base resin layer (cohesive failure occurs inside the base resin layer) ).

  As is clear from Tables 1 to 3, the tab sealing insulating films of Examples 1 to 10 of the present invention are excellent in sealing strength, and even when the internal pressure is increased in an electrochemical device such as a battery. The good sealing state through the insulating film for tab sealing of the invention can be sufficiently maintained.

  On the other hand, in Comparative Example 1, since the thermoplastic elastomer content in the resin composition exceeds 30% by mass, the sealing strength is inferior, and the internal pressure increases in an electrochemical device such as a battery. The good sealing state through the tab sealing insulating film cannot be sufficiently maintained. Further, in Comparative Example 2, the content of the thermoplastic elastomer in the base resin layer exceeds 30% by mass, so that the sealing strength is inferior, and the tab is increased when the internal pressure is increased in an electrochemical device such as a battery. A good sealing state through the sealing insulating film cannot be maintained sufficiently.

  The insulating film for tab sealing which concerns on this invention is used suitably as an insulating film for tab sealing of electrochemical devices, such as a battery and a capacitor.

DESCRIPTION OF SYMBOLS 1 ... Tab sealing insulating film 2 ... Base resin layer 3 ... Outer resin layer 4 ... Inner resin layer 20 ... Electrochemical device 21 ... Positive electrode tab 22 ... Negative electrode tab 23 ... Exterior material

Claims (11)

Including at least a base resin layer composed of a resin composition comprising 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer;
An insulating film for tab sealing, wherein the resin composition has a melting point of 155 ° C. or higher, and the MFR of the resin composition is 10 g / 10 min or less. A base resin comprising a resin composition comprising 70% by mass to 99% by mass of a first resin component made of acid-modified polypropylene and polypropylene not modified with acid, and 1% by mass to 30% by mass of a thermoplastic elastomer. Including at least a layer,
An insulating film for tab sealing, wherein the resin composition has a melting point of 155 ° C. or higher, and the MFR of the resin composition is 10 g / 10 min or less.   The insulating film has a configuration in which an outer resin layer is laminated on a surface of the base resin layer on the exterior material side, and an inner resin layer is laminated on a tab side surface of the base resin layer, and the outer resin layer 3. The tab sealing insulating film according to claim 1, comprising: acid-modified polypropylene or / and polypropylene not modified with acid, and the inner resin layer contains acid-modified polypropylene. The melting point of the outer resin layer is 130 ° C to 140 ° C, the melting point of the inner resin layer is 130 ° C to 140 ° C,
The insulating film for tab sealing according to claim 3, wherein the melting point of the base resin layer is 25 ° C or more higher than the melting point of the outer resin layer and 25 ° C or more higher than the melting point of the inner resin layer.   The insulating film for tab sealing according to claim 4, wherein the melting point of the base resin layer is 25 to 45 ° C higher than the melting point of the outer resin layer and 25 to 45 ° C higher than the melting point of the inner resin layer. The insulating film has a configuration in which an outer resin layer is laminated on a surface of the base resin layer on the exterior material side, and an inner resin layer is laminated on a tab side surface of the base resin layer,
The outer resin layer comprises a resin composition having a melting point of less than 155 ° C., comprising 70% by mass to 99% by mass of acid-modified polypropylene and 1% by mass to 30% by mass of a thermoplastic elastomer,
The inner resin layer is made of a resin composition having a melting point of less than 155 ° C, comprising 70% to 99% by mass of acid-modified polypropylene and 1% to 30% by mass of a thermoplastic elastomer. 2. An insulating film for sealing a tab according to 2. The insulating film has a configuration in which an outer resin layer is laminated on a surface of the base resin layer on the exterior material side, and an inner resin layer is laminated on a tab side surface of the base resin layer,
Melting | fusing point formed by the said outer side resin layer containing 70 mass%-99 mass% of 1st resin components which consist of acid-modified polypropylene and the polypropylene which is not modified | denatured with acid, and 1 mass%-30 mass% of thermoplastic elastomers. Consists of a resin composition of less than 155 ° C,
Melting | fusing point formed by the said inner side resin layer containing 70 mass%-99 mass% of 1st resin components which consist of acid-modified polypropylene and the polypropylene which is not modified | denatured with an acid, and thermoplastic elastomer 1 mass%-30 mass%. The insulating film for tab sealing according to claim 1 or 2, comprising a resin composition having a temperature of less than 155 ° C.   The insulating film for tab sealing according to any one of claims 1 to 7, wherein the thermoplastic elastomer has a melting point of 80 ° C or lower, and the thermoplastic elastomer has an MFR of 5 g / 10 min or less.   The insulating film for tab sealing according to any one of claims 1 to 8, wherein the thermoplastic elastomer is one or two resins selected from the group consisting of ethylene-propylene rubber and ethylene-propylene-butene rubber. .   An electrochemical device comprising the tab sealing insulating film according to claim 1. An exterior material,
An electrochemical element housed in the exterior material;
An inner end portion is electrically connected to the electrochemical element, and an outer end portion is disposed outside the exterior material, and a tab,
The both sides of the tab are sandwiched via the tab sealing insulating film according to any one of claims 1 to 9 by the seal portion of the exterior material, and the seal portion of the exterior material is provided on both sides of the tab. An electrochemical device characterized by being bonded to the substrate.