Sealing tape

Abstract

The purpose of the present invention is to provide a sealing tape that expands inside a housing of, for instance, a lithium ion cell and thereby protects an electrode body from vibration or impact. This sealing tape that acheives the foregoing comprises an adhesive agent layer and a substrate layer that contains fluorine resin and / or (meth)acrylic resin and is disposed on the adhesive agent layer. The sealing tape has multiple openings that open on the surface side of the substrate layer.

Description

sealing tape

[0001] The present invention relates to a sealing tape.

[0002] In recent years, many small, portable electronic devices have been developed, and lithium-ion batteries, electrolytic capacitors, and other devices commonly used in these devices are also required to be smaller and lighter. Lithium-ion batteries, electrolytic capacitors, and other devices typically contain a negative electrode, a positive electrode, a separator separating them, and an electrolyte solution within a housing. To increase the battery's energy density, the negative electrode, separator, and positive electrode are often formed into sheets, which are then stacked and wound together to form an electrode assembly. In such batteries, loosening of the electrode assembly leads to uneven spacing between the electrodes, resulting in reduced battery performance. Therefore, to prevent loosening of the electrode assembly, the end of the electrode assembly is often secured with sealing tape (see, for example, Patent Document 1).

[0003] The sealing tape generally has a base layer made of a resin and a pressure-sensitive adhesive layer disposed on the base layer.

[0004] WO 2009 / 139388

[0005] Here, the diameter of the electrode body fixed with the sealing tape is preferably smaller than the diameter of the housing from the viewpoints of ease of insertion into the housing and prevention of damage due to contact with the housing. On the other hand, if the electrode body is not fixed within the housing, when an external impact or vibration is applied to the battery, the electrode body may shift position or come into contact with the housing, resulting in damage to the electrode body. Therefore, attempts have been made to swell the sealing tape with an electrolyte to increase its thickness and thereby restrict movement of the electrode body within the housing.

[0006] However, after extensive research, the inventors of the present invention found that even if the sealing tape is swelled with an electrolyte, it is difficult to make the thickness of the sealing tape sufficiently large, and further improvements are required.

[0007] The present invention has been made in view of the above-mentioned problems, and specifically aims to provide a sealing tape that swells with an electrolyte solution inside the housing of a lithium ion battery or the like, and can protect an electrode body from vibration and impact.

[0008] The present invention provides the following sealing tapes. [1] A sealing tape comprising a pressure-sensitive adhesive layer and a substrate layer containing a fluorine-based resin and / or a (meth)acrylic resin, disposed on the pressure-sensitive adhesive layer, and having a plurality of openings opening on the surface side of the substrate layer. [2] The sealing tape according to [1], wherein each of the openings is a slit cutting the pressure-sensitive adhesive layer and the substrate layer in the thickness direction. [3] The sealing tape according to [2], wherein the slits are oriented approximately parallel to the MD direction. [4] The sealing tape according to [1], wherein the openings are through-holes penetrating the substrate layer and the pressure-sensitive adhesive layer. [5] The sealing tape according to [1] to [4], wherein the substrate layer contains polyvinylidene fluoride and polyethylene terephthalate. [6] The sealing tape according to any of [1] to [5], further comprising a release layer disposed on an area of ​​the substrate layer other than the openings.

[0009] The sealing tape of the present invention is easily swollen by the electrolyte in the housing of a lithium ion battery or the like, and when used in a lithium ion battery or the like, can protect the electrode body from vibration and impact.

[0010] FIG. 1A is a plan view of a sealing tape according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line A-A in FIG. 1A. FIG. 2A is a plan view of a sealing tape according to another embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line A-A in FIG. 2A. FIGS. 3A to 3D are plan views showing the arrangement patterns of openings in the sealing tapes produced in Examples 1-1 to 1-4, respectively. FIG. 4 is a graph showing the relationship between the total slit length of the openings in the sealing tapes produced in Examples 1-1 to 1-7 and Comparative Example 1 and the average peak test force. FIGS. 5A to 5C are plan views showing the patterns of openings in the sealing tapes produced in Examples 2-1 to 2-15, respectively. FIG. 6A is a graph showing the relationship between the number of holes (per sheet) and the average peak test force [N] in the sealing tapes produced in Examples 2-1 to 2-9, and FIG. 6B is a graph showing the relationship between the total slit length of the openings in the sealing tapes produced in Examples 2-1 to 2-15 and Comparative Example 2 and the average peak test force [N] in the 100 mm openings in the sealing tapes. ２ 1 is a graph showing the relationship between the open area per square inch and the average peak test force.

[0011] In this specification, the MD direction refers to the flow direction during film production and also refers to the direction in which the formed sealing tape is wound up, and the TD direction refers to the direction perpendicular to the flow direction during film production and also refers to the direction perpendicular to the direction in which the formed tape is wound up.

[0012] The sealing tape of the present invention is a member for fastening the end of a wound electrode assembly formed by winding a negative electrode, a separator, and a positive electrode of a lithium-ion battery, etc. After the electrode assembly is housed in a housing of a battery, etc., the sealing tape swells with an electrolyte solution and also serves to protect the electrode assembly from external impacts, etc.

[0013] As mentioned above, conventional sealing tapes swell only slightly when swelled with an electrolyte solution, making it difficult to achieve a sufficient thickness, making it difficult to fill the gap between the electrode assembly and the housing. In contrast, the sealing tape of the present invention has multiple openings on the surface of the base layer. This makes it easy for dense protrusions (wrinkles) to form when the sealing tape (base layer) swells with an electrolyte solution. Furthermore, the protrusions (wrinkles) contact the housing in a linear or point-like manner, thereby fixing the electrode assembly in a predetermined position and preventing its movement. Therefore, in a battery using this sealing tape, the electrode assembly is less likely to be damaged, even when subjected to external vibrations or impacts.

[0014] Here, Fig. 1A shows a plan view of a sealing tape according to one embodiment of the present invention, and Fig. 1B shows a cross-sectional view taken along line A-A in Fig. 1A. As shown in Fig. 1B, the sealing tape 10 of this embodiment has an adhesive layer 12, a base layer 14, and a release layer 16. As shown in Figs. 1A and 1B, the sealing tape 10 has a plurality of openings 18 opening on the surface of the base layer 14, and the openings 18 are formed by slits cutting the release layer 16, the base layer 14, and the adhesive layer 12 in the thickness direction. In this specification, the upper surface of Fig. 1B will be referred to as the "surface" of the sealing tape 10 or each layer, and the lower surface of Fig. 1B will be referred to as the "back surface" of the sealing tape 10 or each layer.

[0015] The reason why dense protrusions (wrinkles) are formed when a sealing tape 10 having such a structure is swelled with an electrolyte is unclear, but it is thought to be as follows. Since the sealing tape 10 of this embodiment has the openings 18, when an electrolyte is filled into a housing such as a battery, not only the surface of the base layer 14 but also the base layer 14 and adhesive layer 12 constituting the outer wall of the openings 18 come into contact with the electrolyte and swell. At this time, swelling progresses not only from the four edges of the sealing tape but also from multiple openings 18, which makes it easier for dense protrusions (wrinkles) to form uniformly and quickly on the surface of the sealing tape. Therefore, it is thought that much denser protrusions (wrinkles) are formed uniformly compared to sealing tapes without openings 18. Furthermore, in general, in sealing tapes 10 including a release layer 16, the base layer 14 is covered by the release layer 16, which may make it difficult for the electrolyte to come into contact with the surface of the base layer 14. In contrast, in the present embodiment, since the openings 18 are provided, the electrolyte can reliably contact the base material layer 14 through the openings 18, thereby forming the raised portions. The density of the formed raised portions can be visually confirmed.

[0016] In this embodiment, the release layer 16 is disposed on the base layer 14, but the release layer 16 may not be provided depending on the type of the sealing tape 10. Below, each layer constituting the sealing tape 10 and the shape of the opening 18 will be described in detail.

[0017] (1) Substrate Layer The substrate layer 14 of this embodiment is a layer containing a fluorine-based resin and / or a (meth)acrylic resin. The substrate layer 14 may contain only one of the fluorine-based resin and the (meth)acrylic resin, or may contain both. However, it is more preferable that the substrate layer 14 contains either the fluorine-based resin or the (meth)acrylic resin as the base resin. In this specification, "(meth)acrylic" means methacrylic, acrylic, or both.

[0018] Examples of the fluorine-based resin include a homopolymer of vinylidene fluoride (polyvinylidene fluoride) and a copolymer of vinylidene fluoride monomer and another monomer. Examples of other monomers copolymerizable with the vinylidene fluoride monomer include vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene. The base layer 14 may contain only one of these or two or more of these. Among these, when the base layer 14 contains a copolymer of vinylidene fluoride monomer and another monomer, the base layer 14 is particularly likely to swell in the electrolyte solution used in lithium-ion batteries, etc. Furthermore, when the base layer 14 contains polyvinylidene fluoride, the strength of the sealing tape 10 is high, and the strength when the electrode assembly is wound around the base layer 14 is particularly likely to be high.

[0019] Here, when the substrate layer 14 contains the above-mentioned fluorine-based resin as the base resin, the substrate layer 14 may contain only the fluorine-based resin, or may contain one or more of polyethylene terephthalate (PET), nitrile rubber (NBR), hydrogenated styrene-based thermoplastic elastomer (SEBS), acrylic thermoplastic elastomer (MAM), etc. in addition to the above-mentioned fluorine-based resin. When the substrate layer 14 contains a resin other than the fluorine-based resin, the flexibility of the substrate layer 14 and, therefore, the flexibility of the sealing tape 10 are improved. However, the amount of the fluorine-based resin relative to the total mass of the resins constituting the substrate layer 14 is preferably 85 mass% or more, more preferably 90 mass% or more. When the amount of the fluorine-based resin is 85 mass% or more, the substrate layer 14 is easily formed into a film and the strength of the substrate layer 14 is easily increased.

[0020] On the other hand, examples of (meth)acrylic resins include homopolymers and copolymers of (meth)acrylic acid alkyl esters. Examples of (meth)acrylic acid alkyl esters include (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 4 to 20 carbon atoms. Specific examples thereof include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. The (meth)acrylic resin may also be a copolymer of the above-mentioned (meth)acrylic acid alkyl ester and another monomer. However, the amount of repeating units derived from the (meth)acrylic acid alkyl ester in the (meth)acrylic resin is preferably 50% by mass or more, more preferably 70% by mass or more. The base layer 14 may contain only one type of (meth)acrylic resin, or may contain two or more types.

[0021] Furthermore, when the substrate layer 14 contains the above-mentioned (meth)acrylic resin as a base resin, the substrate layer 14 may contain only the (meth)acrylic resin, or may contain one or more of nitrile rubber (NBR), hydrogenated styrene-based thermoplastic elastomer (SEBS), acrylic thermoplastic elastomer (MAM), etc. in addition to the above-mentioned (meth)acrylic resin. When the substrate layer 14 contains a resin other than the (meth)acrylic resin, the flexibility of the substrate layer 14 and, ultimately, the flexibility of the sealing tape 10 tends to be improved. However, the amount of the (meth)acrylic resin relative to the total mass of the resins constituting the substrate layer 14 is preferably 50% by mass or more, more preferably 70% by mass or more. When the amount of the above-mentioned (meth)acrylic resin is 50% by mass or more, the film-forming properties of the substrate layer 14 tend to be improved and the strength of the substrate layer 14 tends to be increased.

[0022] In addition to the resin components, the base layer 14 may further contain fillers, additives, etc., as long as the objects and effects of the present invention are not impaired. However, from the viewpoint of the swelling property of the base layer 14, the amount of the resin components relative to the total mass of the base layer 14 is preferably 90 mass % or more, and more preferably 95 mass % or more.

[0023] Here, the base layer 14 may be composed of one layer, or may be composed of two or more layers of the same or different types.

[0024] The thickness of the substrate layer 14 (the entire substrate layer 14 when it is composed of multiple layers) is preferably 20 μm or more and 70 μm or less, and more preferably 30 μm or more and 50 μm or less. When the thickness of the substrate layer 14 is 20 μm or more, the strength of the substrate layer 14 is high, and even if the sealing tape 10 has the openings 18, the sealing tape 10 is less likely to tear or cut. On the other hand, when the thickness of the substrate layer 14 is 70 μm or less, the thickness of the sealing tape 10 does not become excessively thick, and it is possible to miniaturize lithium ion batteries, electrolytic capacitors, capacitors, etc.

[0025] (2) Adhesive Layer The adhesive layer 12 may be any layer that has adhesiveness for attaching the base layer 14 to the electrode body and that can maintain its adhesiveness even when immersed in an electrolyte solution. The adhesive layer 12 may swell in the electrolyte solution together with the base layer 14, as long as it can maintain its adhesiveness.

[0026] The pressure-sensitive adhesive layer 12 can be a layer made of a pressure-sensitive adhesive, and examples of pressure-sensitive adhesives include various types of pressure-sensitive adhesives such as known (meth)acrylic pressure-sensitive adhesives, polyisoprene pressure-sensitive adhesives, styrene-butadiene random copolymer pressure-sensitive adhesives, styrene-isoprene block copolymer pressure-sensitive adhesives, butyl rubber pressure-sensitive adhesives, polyisobutylene pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, etc. The pressure-sensitive adhesive layer 12 may contain only one type of the above-mentioned various pressure-sensitive adhesives, or may contain two or more types.

[0027] The thickness of the adhesive layer 12 is preferably 5 μm or more and 20 μm or less, and more preferably 10 μm or more and 20 μm or less. When the thickness of the adhesive layer 12 is 5 μm or more, the adhesive layer 12 is more likely to exhibit adhesiveness. On the other hand, when the thickness of the adhesive layer 12 is 20 μm or less, the thickness of the sealing tape 10 does not become excessively thick, and it is possible to miniaturize lithium ion batteries, electrolytic capacitors, capacitors, etc.

[0028] (3) Release Layer As described above, the sealing tape 10 of this embodiment further has a release layer 16 on the region other than the opening 18 of the base layer 14. The release layer 16 is a layer for preventing the adhesive layer 12 from adhering excessively to the surface of the base layer 14 when the sealing tape 10 is rolled up and stored, which would prevent the adhesive layer 12 from becoming unable to peel off when the sealing tape 10 is used, or for preventing the adhesive layer 12 from remaining on the surface of the base layer 14.

[0029] The release layer 16 is not particularly limited as long as it is a layer formed from a material having releasability. Examples of materials having releasability include known materials such as silicone resins, fluorine-based resins, long-chain alkyl resins, and fatty acid amides. The release layer 16 may contain only one of these materials, or may contain two or more of them.

[0030] The thickness of the release layer 16 is preferably 0.5 μm or more and 3.0 μm or less, and more preferably 1.0 μm or more and 2.0 μm or less. When the thickness of the release layer 16 is in this range, the release layer 16 can easily exert its effect sufficiently, and the handling of the sealing tape 10 tends to be good.

[0031] (4) Shape of Sealing Tape and Opening The shape of the sealing tape 10 of this embodiment is not particularly limited. For example, it may be a sheet-like tape processed to a desired width and a desired length, but it is preferably a long tape wound into a roll. If the sealing tape 10 is a roll-like tape, it can be cut to the desired length and used, and further, a protective member or the like for protecting the adhesive layer 12 is not required. Another advantage is that it can be manufactured continuously. The width (length in the TD direction during manufacturing) can be changed appropriately depending on the application of the sealing tape 10.

[0032] As described above, the sealing tape 10 of this embodiment has a plurality of openings 18 each consisting of a slit, which cuts the sealing tape 10 in the thickness direction from the surface of the release layer 16 to the back surface of the pressure-sensitive adhesive layer 12, as shown in FIG. 1B . However, the thickness direction shape of the openings 18 each consisting of a slit in this embodiment is not limited to this shape. For example, the openings (slits) 18 may be formed so as to cut only the release layer 16 and the base layer 14. Alternatively, the openings (slits) 18 may be formed so as to cut the base layer 14 to a certain depth. However, from the viewpoint of increasing the contact area between the base layer 14 and the electrolyte and swelling the pressure-sensitive adhesive layer 12, it is preferable that the openings (slits) 18 be formed so as to cut the sealing tape 10 in the thickness direction from the surface of the release layer 16 to the back surface of the pressure-sensitive adhesive layer 12, as shown in FIG. 1B .

[0033] In addition, in this embodiment, when the sealing tape 10 is viewed in a plan view, the orientations of the multiple openings (slits) 18 are all approximately parallel to the MD direction (within ±15° of the MD direction). However, the orientation of the multiple openings (slits) 18 is not limited to this, and may be, for example, approximately parallel to the TD direction (within ±5° of the TD direction), or may be other orientations. If the orientation of each opening (slit) 18 is approximately parallel to the MD direction, even if force is applied in the MD direction during manufacturing of the sealing tape, the opening (slit) 18 is unlikely to tear or break starting from the opening (slit) 18. Note that in this embodiment, the orientations of the multiple openings (slits) 18 are all the same, but the orientations of some or all of the openings (slits) may be different.

[0034] In addition, in this embodiment, when the sealing tape 10 is viewed in a plan view, the shape of each opening (slit) 18 is linear, but this is not limited to this and may be wavy or the like.

[0035] Furthermore, when the sealing tape 10 is viewed in plan, the length of each opening (slit) 18 is not particularly limited and is selected appropriately depending on the application of the sealing tape 10 (e.g., the diameter of a battery), but is preferably 1 mm to 20 mm, and more preferably 3 mm to 10 mm. When the length of each slit is within this range, the sealing tape 10 is less likely to tear or break from the opening (slit) 18 during production or use. The width of the slit may be shorter than the length and is selected appropriately depending on the application of the sealing tape 10 (e.g., the diameter of a battery), but is preferably 3 mm or less, and more preferably 1 mm or less. The width of each slit is preferably shorter from the viewpoint of making it easier for wrinkles to form when the sealing tape swells, and there is no particular lower limit, but the width can be 0 mm in the case of a slit consisting simply of a cut.

[0036] In this embodiment, three openings (slits) 18 are arranged in the TD direction. However, the number of openings (slits) 18 arranged in the TD direction is appropriately selected according to the width of the sealing tape 10. In this embodiment, the openings (slits) 18 are arranged at equal intervals in the MD direction, but the arrangement intervals of the openings (slits) 18 do not have to be constant. However, when the sealing tape 10 is viewed in plan, ２ The total length of the openings (slits) 18 present per area is preferably 1 mm or more and 26 mm or less, and more preferably 2 mm or more and 13 mm or less. When the total length of the openings (slits) 18 present per area is within this range, dense protrusions can be uniformly formed by swelling of the electrolyte, making it easier to further restrict movement of the electrode body within the battery.

[0037] (5) Manufacturing Method of Sealing Tape The manufacturing method of the sealing tape of this embodiment is not particularly limited, but it can be manufactured by, for example, the following method. Note that, although the manufacturing method of a long sealing tape will be described below, it can be appropriately changed according to the shape and performance of the desired sealing tape.

[0038] First, a long substrate layer 14 is prepared. Then, a pressure-sensitive adhesive is applied to one side of the substrate layer 14, and a material having releasability is applied to the other side. These may be applied simultaneously or separately. Then, heating or the like is performed as necessary to obtain a laminate in which the adhesive layer 12 is formed on one side of the substrate layer 14 and the release layer 16 is formed on the other side. Furthermore, the slits are made at desired positions in the laminate using a jig with multiple blades to form the openings 18, thereby obtaining the sealing tape 10 described above.

[0039] (6) Other Embodiments In the above-described embodiment, the sealing tape 10 has the opening 18 formed by a slit, but the structure of the opening 18 is not limited to a slit. Hereinafter, a sealing tape 20 of another embodiment will be described with reference to Figures 2A and 2B. However, the sealing tape 20 is similar to the above-described sealing tape 10 except for the shape of the opening 18. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0040] FIG. 2A is a plan view of the sealing tape 20 according to this embodiment, and FIG. 2B is a cross-sectional view taken along line A-A in FIG. 2A. As shown in FIG. 2A, the sealing tape 20 according to this embodiment includes an adhesive layer 12, a base layer 14, and a release layer 16. As shown in FIGS. 2A and 2B, the sealing tape 20 also includes a plurality of openings 28 on the surface of the base layer 14, each of which is formed by a through-hole penetrating the release layer 16, the base layer 14, and the adhesive layer 12. Even in the sealing tape 20 having openings 28 formed by the through-holes, the electrolyte swells not only the surface of the base layer 14 but also the base layer 14 and the adhesive layer 12 present on the wall surfaces of the openings 28. At this time, swelling proceeds not only from the four edges of the sealing tape but also from the outer edges and wall surfaces of the plurality of openings 28, which makes it easy for dense protrusions (wrinkles) to form uniformly and quickly on the surface of the sealing tape. Furthermore, in general, in a sealing tape including the release layer 16, the base layer 14 is covered with the release layer 16, and therefore it may be difficult for the electrolyte to come into contact with the surface of the base layer 14. In contrast, in the present embodiment, since the above-mentioned openings 28 are also provided, the electrolyte can reliably come into contact with the base layer 14 through the openings 28, and the above-mentioned protrusions are likely to be formed.

[0041] Here, in the sealing tape 20 of this embodiment, a large number of openings (through holes) 28 that are opened in a substantially cylindrical shape are arranged. However, the shape of the openings (through holes) 28 is not limited to this shape, and may be, for example, a prismatic shape, a truncated cone shape, a truncated pyramid shape, or the like. Furthermore, in this embodiment, the shapes of the plurality of openings (through holes) 28 are all the same, but the shapes of the plurality of openings (through holes) 28 may be different from one another. In this case, the opening area of ​​each opening (through hole) 28 on the surface of the base material layer 14 is 0.2 mm ２ More than 20 mm ２ Preferably, it is 0.3 mm or less. ２ More than 10 mm ２ It is more preferable that the opening area of ​​the opening (through hole) 28 is 20 mm or less. ２ If the opening area of ​​the opening (through hole) 28 is 0.2 mm or less, the area of ​​the region other than the opening, i.e., the area of ​​the region where the swelling causes the protrusion (wrinkle), can be sufficiently secured. Therefore, the swollen sealing tape 20 is likely to come into contact with the housing of the battery or the like. On the other hand, if the opening area of ​​the opening (through hole) 28 is 0.2 mm or less, the area of ​​the region other than the opening, i.e., the area of ​​the region where the swelling causes the protrusion (wrinkle) can be sufficiently secured. Therefore, the swollen sealing tape 20 is likely to come into contact with the housing of the battery or the like. ２ If this is the case, the electrolyte can easily penetrate into the sealing tape 20, and dense protrusions (wrinkles) can easily be formed.

[0042] In this embodiment, three openings (through holes) 28 are arranged in the TD direction, but the number of openings (through holes) 28 arranged in the TD direction is appropriately selected according to the width of the sealing tape 20. In this embodiment, the openings (through holes) 28 are arranged at equal intervals in the MD direction, but the arrangement intervals of the openings (through holes) 28 do not have to be constant. However, when the sealing tape 20 is viewed in plan, ２ The total area of ​​the openings (through holes) 28 present around 0.1 mm ２ More than 15mm ２ It is preferable to arrange the openings (through holes) 28 so that the gap is 0.2 mm or less. ２ More than 8mm ２ It is more preferable to arrange the openings (through holes) 28 so that the total area of ​​the openings (through holes) 28 is within this range. When the total area of ​​the openings (through holes) 28 is within this range, dense protrusions can be uniformly formed by swelling of the electrolyte, making it easier to further restrict movement of the electrode body within the battery.

[0043] The sealing tape 20 of this embodiment can be manufactured by the following method. First, a long substrate layer 14 is prepared. Then, a pressure-sensitive adhesive is applied to one side of the substrate layer 14, and a material having releasability is applied to the other side. These may be applied simultaneously or separately. Then, heating or the like is performed as necessary to obtain a laminate in which the adhesive layer 12 is formed on one side of the substrate layer 14 and the release layer 16 is formed on the other side. Furthermore, a number of openings (through holes) 28 are formed at desired positions in the laminate using a punching jig, thereby obtaining the sealing tape 10.

[0044] (7) Uses As described above, the sealing tape of any of the above-described embodiments is very useful as a tape for securing an electrode body such as a lithium-ion battery. When securing the electrode body, the method of applying the sealing tape is appropriately selected depending on the type, dimensions, performance, etc. of the battery. For example, the sealing tape may be wrapped around the electrode body more than once, or may be applied only to a portion of the electrode body.

[0045] Furthermore, the type of electrolyte used in combination with the sealing tape is not particularly limited, but from the viewpoint of easily swelling the above-mentioned sealing tape, an electrolyte containing one or more of ethylene carbonate, dimethyl carbonate, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, methyl propionate, ethyl propionate, and mixed solvents thereof is particularly preferred.

[0046] Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these.

[0047] Example 1-1 A sealing tape was prepared having a width (length in the transverse direction) of 53 mm and a length (length in the machine direction) of 50 mm. The sealing tape was composed of a 1 μm-thick release layer made of a long-chain alkyl resin (Peiroil 1010, backside release agent, manufactured by Lion Specialty Chemicals), a 40 μm-thick base layer containing polyvinylidene fluoride (KF#1000, manufactured by Kureha) and a crystalline polyethylene terephthalate (PET) resin (A12, manufactured by Eastman Chemical) in a mass ratio of 90:10, and a 10 μm-thick adhesive layer made of an acrylic adhesive (AS-501, manufactured by Lion Specialty). As shown in FIG. 3A, a total of nine 6 mm-long slits (openings) were formed in the sealing tape, arranged in three rows of three, approximately parallel to the machine direction. The slits were formed so as to cut from the surface of the base layer to the backside of the adhesive layer. Table 1 shows the TD and MD pitches of the slits, the slit length, the total slit length, etc.

[0048] [Examples 1-2 to 1-7] Slits were formed in the sealing tape in the same manner as in Example 1-1, except that the number of slits, the pitch in the TD direction, the pitch in the MD direction, and the direction of the slits were changed as shown in Table 1 below. The arrangement pattern of the slits created in Example 1-2 is shown in Figure 3B, the arrangement pattern of the slits created in Example 1-3 is shown in Figure 3C, and the arrangement pattern of the slits created in Example 1-4 is shown in Figure 3D.

[0049] Comparative Example 1 A sealing tape without slits was prepared as Comparative Example 1.

[0050] [Evaluation] The sealing tapes produced in Examples 1-1 to 1-7 and Comparative Example 1 were evaluated as follows.

[0051] (1) Preparation of sealing tape sample A PPS (polyphenylene sulfide) rod with an outer diameter of 17.5 mm and a height of 70.0 mm was prepared, and a hanging bracket was attached to the top surface of the rod. Then, sealing tape was attached to the outer periphery of the rod so that the height direction of the rod was the TD direction and the circumferential direction was the MD direction. The sample was left in this state overnight.

[0052] (2) Test: 0.5 mL of electrolyte (EC / DMC = 1:1) was poured into a metal tube (housing) with an inner diameter of 17.7 mm and a height of 68.0 mm. The round bar with the sealing tape prepared in (1) above was then inserted and placed in a gear oven at 45°C for 5 hours. The tube (housing) was then removed from the gear oven and allowed to cool to room temperature. The bottom of the tube (housing) was then fixed to a fixed metal plate with double-sided tape. The hanging hardware of the round bar was then engaged with a dedicated jig (hook) clamped by the upper chuck of the autograph. The round bar was then pulled vertically upward at a tensile speed of 100 mm / min using the autograph. This measurement was performed three times, and the average peak test force (first convex point) was calculated. Table 1 also shows the relative peak test force (average value) of each example, with the peak test force (average value) of the comparative example taken as 100%. FIG. 4 shows the relationship between the total slit length of each sealing tape and the average peak test force.

[0053] [result]

[0054] As shown in Table 1 and Figure 4 above, regardless of the number or pitch of the slits, the peak test force of the slit-free comparative example 1 was approximately 2.3 times or more higher in all cases (Examples 1-1 to 1-7). This is thought to be because the sealing tape was sufficiently swollen by the electrolyte, resulting in the uniform formation of dense raised portions (wrinkles), which in turn reduced the gap between the round bar and the tube (housing). Furthermore, as shown in Figure 4, there was no significant difference in the average peak test force regardless of whether the total slit length was long or short.

[0055] [Example 2-1] A sealing tape having a width (length in the transverse direction) of 53 mm and a length (length in the machine direction) of 50 mm was prepared, which was a laminate consisting of a release layer of a 1 μm thick long-chain alkyl pendant polymer (backside release agent PEOIL 1010 manufactured by Lion Specialty Chemicals), a 40 μm thick base layer containing polyvinylidene fluoride (KF#1000 manufactured by Kureha) and polyethylene terephthalate (PET) resin (A12 manufactured by Eastman Chemical) in a mass ratio of 90:10, and a 10 μm thick acrylic pressure-sensitive adhesive layer (AS-501 manufactured by Lion Specialty). Two through holes (openings) with a diameter of 0.6 mm were formed in the machine direction and three in the transverse direction, for a total of six through holes.

[0056] [Examples 2-2 to 2-15] As shown in Tables 2 and 3 below, a plurality of through holes (openings) were made in the sealing tape in the same manner as in Example 2-1, except that the number of through holes, the diameter of the through holes, and the arrangement pitch were changed. In Examples 2-4 to 2-15, the through holes were formed by punching. The arrangement patterns of the through holes formed in Examples 2-1, 2-4, 2-7, 2-10, and 2-13 are shown in FIG. 5A, the arrangement patterns of the through holes formed in Examples 2-2, 2-5, 2-8, 2-11, and 2-14 are shown in FIG. 5B, and the arrangement patterns of the through holes formed in Examples 2-3, 2-6, 2-9, 2-12, and 2-15 are shown in FIG. 5C.

[0057] Comparative Example 2 A sealing tape without a slit was prepared as Comparative Example 2.

[0058] [Evaluation] The sealing tapes produced in Examples 2-1 to 2-15 and Comparative Example 2 were evaluated in the same manner as in Example 1-1. The results are shown in Tables 2 and 3. The relationship between the number of holes and the average peak test force of Examples 2-1 to 2-9 is shown in FIG. 6A. ２ The relationship between the perforation area and the average peak test force is shown in FIG. 6B.

[0059] [result]

[0060]

[0061] As shown in Tables 2 and 3 and Figures 6A and 6B, although there was some variation depending on the total area of ​​the through-holes (openings) and the number of holes, the peak test force in all of the examples (Examples 2-1 to 2-15) was approximately 1.7 times or more the peak test force of Comparative Example 2, which had no through-holes. This is thought to be because the sealing tape was sufficiently swollen by the electrolyte, resulting in the uniform formation of the dense protrusions (wrinkles) described above, and the gap between the round bar and the tube (housing) becoming sufficiently small. As can be seen from Figures 6A and 6B, a good peak test force can be obtained by appropriately adjusting the number of through-holes and the opening area.

[0062] This application claims priority from Japanese Patent Application No. 2024-006807, filed January 19, 2024. The contents of the specification and drawings of said application are incorporated herein by reference in their entirety.

[0063] The sealing tape of the present invention swells with the electrolyte inside the housing of a lithium ion battery and can protect the electrode assembly from vibration and impact, making it extremely useful in the field of battery manufacturing, particularly in the field of lithium ion battery manufacturing.

[0064] 10, 20 Sealing tape 12 Adhesive layer 14 Base layer 16 Release layer 18 Opening (slit) 28 Opening (through hole)

Claims

1. A sealing tape comprising an adhesive layer and a base material layer disposed on the adhesive layer and containing a fluororesin and / or a (meth)acrylic resin, the base material layer having a plurality of openings that open to the surface side of the base material layer.

2. The sealing tape according to claim 1, wherein each of the openings is a slit that cuts through the adhesive layer and the base material layer in the thickness direction.

3. The sealing tape according to claim 2, wherein the direction of the slit is substantially parallel to the MD direction.

4. The sealing tape according to claim 1, wherein the openings are through holes that penetrate the adhesive layer and the base material layer.

5. The sealing tape according to claim 1, wherein the base material layer contains polyvinylidene fluoride and polyethylene terephthalate.

6. The sealing tape according to claim 1, further comprising a release layer disposed on a region of the base material layer other than the openings.

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