JP2005056658A - Lithium-ion battery element winding adhesive tape or sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element which can impregnate an element with an electrolyte in a short time by exhibiting high permeability to the electrolyte and has sufficient adhesion.
SOLUTION: The pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element of the present invention has a base material composed of a porous film and a pressure-sensitive adhesive layer provided in a fibrous form on one side of the base material. It is characterized by. The base material may be composed of, for example, a porous film having a porosity of 10 to 80%, or may be composed of a porous film having heat resistance. The lithium ion battery of the present invention is characterized in that the element is wound with the above-described lithium ion battery element winding adhesive tape or sheet.
[Selection] Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive tape or sheet used as a constituent material of a lithium ion battery including a manganese-based or cobalt-based positive electrode, and a lithium ion battery using the same.

  Conventionally, in a lithium ion battery, a positive electrode foil and a cathode foil are wound around an outer periphery of a lithium ion battery element wound with electrolytic paper (separator paper), and an adhesive tape is wound around and fixed. It is housed inside and is made by injecting an electrolyte and impregnating the element. However, when injecting the electrolytic solution, there is a problem that it takes a very long time for the electrolytic solution to penetrate into the element inside the wound body. As a means for solving this problem, a method of infiltrating the electrolytic solution from the lower end of the wound body (for example, see Patent Document 1), or a slit-shaped electrolytic solution guide that reaches both ends when the wound body is formed on the surface of the positive foil. A method of providing a plurality of voids (for example, see Patent Document 2) has been proposed.

JP 2000-277094 A JP 2001-35484 A

Adhesive tape (adhesive insulating tape) is used on the outer periphery of the wound body constituting the lithium ion battery to maintain, protect and insulate the form of the wound body. If the permeability can be improved, the time required for the electrolyte injection process can be further shortened.
Accordingly, an object of the present invention is to provide a lithium ion battery element winding pressure-sensitive adhesive tape or sheet having sufficient adhesiveness while impregnating the element with the electrolyte in a short time by exhibiting high permeability to the electrolyte. Is to provide.
Moreover, the objective of this invention is providing the lithium ion battery using said adhesive tape or sheet | seat for lithium ion battery element winding.

  As a result of intensive investigations to achieve the above object, the present inventors, according to the pressure-sensitive adhesive tape or sheet having a specific structure, are required to inject the electrolytic solution by improving the permeability of the electrolytic solution in the wound body. The inventors have found that the time can be shortened and that a lithium ion battery can be efficiently manufactured, and the present invention has been completed.

  That is, this invention provides the adhesive tape or sheet | seat for lithium ion battery element winding which has the base material comprised with the porous film, and the adhesive layer provided in the fiber form on the single side | surface of this base material. The base material is preferably composed of a porous film having a porosity of 10 to 80%, and may be composed of a heat-resistant porous film.

  Moreover, this invention provides the lithium ion battery by which the element is wound with the adhesive tape or sheet | seat for lithium ion battery element winding of the said invention.

  According to the adhesive tape or sheet for winding a lithium ion battery element of the present invention, since it has a specific base material and a fibrous adhesive layer, when used as a constituent material of a lithium ion battery, The extremely high permeability can be exhibited, the impregnation time of the electrolytic solution into the element can be greatly shortened, and the element can be fixed by winding with sufficient adhesiveness. By using such an adhesive tape or sheet, a lithium ion battery can be produced with high productivity.

Embodiments of the present invention will be described below with reference to the drawings as necessary.
FIG. 1 is a schematic sectional view showing an example of a pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element of the present invention. The pressure-sensitive adhesive tape or sheet includes a base material 1, a pressure-sensitive adhesive layer 2 provided on one surface of the base material 1, a release film 3 provided on the surface of the pressure-sensitive adhesive layer 2, and another base material 1. It is comprised by the back surface processing layer 4 provided in the surface.

  One of the features of the pressure-sensitive adhesive tape or sheet of the present invention is that the substrate 1 is composed of a porous film. The substrate 1 is composed of a porous film having pores 5 on the surface and inside, and examples of the forming material thereof include polyethylene, polypropylene (PP), polyvinyl chloride, and ethylene-vinyl acetate copolymer (EVA). Polyolefins; Polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN); polyarylate; polyurethane; polycarbonate; polyamide; polyimide (PI); polyphenylene sulfide (PPS); , And complexes thereof. Among them, a porous film having heat resistance is preferable in that it is used as a constituent material of a lithium ion battery. Particularly, an ultrahigh molecular weight polyolefin-based porous film (for example, a porous film made of polyolefin having a weight average molecular weight of 300,000 to 5,000,000) Film) is preferred.

The porosity of the substrate 1 is calculated by the following formula.
Porosity (volume%) = {1-[(m / r) / (s × d)]} × 100
[Wherein, m represents weight (g), r represents specific gravity of the forming material, s represents the area (cm ² ) of one side of the film, and d represents thickness (cm)]
The porosity of the substrate 1 is, for example, 10% to 80%, preferably 20% to 70%. When the porosity is 10% or less, it is difficult to obtain the effect of shortening the injection time of the electrolytic solution. When the porosity is 80% or more, the adhesive strength, which is an inherent characteristic of the adhesive tape or sheet, is attenuated, and the element is wound. The performance tends to decrease. The adjustment of the porosity of the substrate 1 is performed by controlling the conditions (such as the type of film forming material, the formation method of the pores, and the conditions thereof) when manufacturing the porous film.

  In this invention, since the base material 1 is comprised with the porous film, the permeability with respect to the electrolyte solution of the base material 1 can be improved. Therefore, when the electrolytic solution is injected into the wound body in which the adhesive tape using the base material is wound around the outer periphery of the element, the adhesive tape on the outermost periphery of the wound body is efficiently penetrated until the element is impregnated. Time (electrolyte injection time) can be greatly shortened.

  The thickness of the base material 1 can be appropriately selected within a range not impairing the workability of the lithium ion battery element winding, and is generally about 1 to 150 μm, preferably about 10 to 100 μm.

  The base material 1 is formed, for example, by forming a sintered body obtained by heating and sintering the forming material powder constituting the base material 1 into a sheet shape, and subjecting the obtained film to a stretching treatment. After that, the film can be produced by impregnating a dispersion of forming material particles constituting the substrate 1 and removing the solvent of the dispersion. As a specific example, an ultra-high molecular weight polyolefin porous film preferably used as the substrate 1 in the present invention is obtained by heating and sintering ultra-high molecular weight polyolefin powder to obtain a porous film, which is subjected to stretching treatment, The dispersion liquid) can be used to form pores in the film.

  More specifically, for example, the base material 1 is manufactured by filling a shape-holding tool with powder of a forming material of the base material 1 and, if necessary, heat-sintering with water vapor or the like to obtain the sintered material obtained. This is done by cutting the body into a sheet shape with a cutting lathe or the like. As the powder of the forming material, those having an average particle diameter in the range of, for example, 10 to 200 μm are used. The shape retainer can prevent scattering of the forming material powder and maintain the molten powder in a predetermined shape. The shape retainer has, for example, a structure in which a large number of holes are perforated in a mold and a heat-resistant porous sheet is adhered to the inner surface. As the heat-resistant porous sheet, polytetrafluoroethylene (PTFE) is used. A porous sheet, a wire netting sheet, a glass cloth or the like can be used. Heat sintering is performed by putting a shape-filling tool filled with powder into a pressure vessel, exhausting the air in the pressure vessel, and then introducing steam heated to a melting point of the powder forming material as necessary. . The introduced water vapor is usually pressurized, so that the inside of the heat-resistant container becomes negative pressure, and the water vapor can easily enter between the forming material powders to quickly transfer heat, and heat sintering is not uneven for a short time. Can be done. In the porous film thus obtained, a plurality of polymer particles (formation material powder) are connected to each other, and a porous structure is formed by voids between the particles.

  Next, the heat-sintered molded film is subjected to stretching treatment using a conventional stretching machine as necessary for the purpose of improving the porosity. The stretching treatment is preferably performed while heating at a temperature below the melting point of the forming material of the substrate 1. When an ultrahigh molecular weight polyolefin is used as a forming material, for example, it is heated in a range of 110 to 135 ° C. and stretched. Stretching may be uniaxial stretching or biaxial stretching. The stretching ratio is, for example, 1.2 to 15 times, preferably 2 to 5 times the sheet length before stretching. According to the above stretching treatment, the porosity of the porous film can be improved, so that the electrolyte injection time can be further shortened when the lithium ion battery is used as a constituent material.

  The forming material particles of the substrate 1 are dispersed in a solvent to obtain a dispersion, and the dispersion is impregnated into a porous film after being heated or sintered or stretched, followed by natural drying or forced drying (hot air) or the like. This is done by removing the solvent. As the particles of the forming material, those having a large specific surface area are preferable. The particle diameter of the forming material particles is preferably smaller than the pore diameter of the porous film. Specifically, as the average particle diameter of the forming material particles with respect to the average pore diameter of the porous film, for example, the former is 10 to 200 μm. The latter is in the range of 0.1 to 10 [mu] m, preferably the former is in the range of 50 to 150 [mu] m and the latter is in the range of 0.1 to 7 [mu] m. Within the above range, the particles do not have a risk of blocking the pores of the porous film and are likely to be accommodated in the film pores. As the solvent for dispersing the particles, for example, water; organic solvents such as alcohol (methanol, ethanol, etc.) and toluene can be used alone or in combination of two or more. The particle concentration in the dispersion is, for example, in the range of 0.5 to 30% by weight, preferably 1 to 10% by weight.

  The impregnation method is not particularly limited, and for example, a method of immersing the porous film in the dispersion, a method of applying the dispersion to the porous film, or the like can be used. It is preferable that the dispersion is sufficiently permeated into the pores of the porous film by the impregnation treatment. The drying for removing the solvent is preferably performed in a temperature range in which the forming material particles are not melted and the particle shape is not completely destroyed. According to such a temperature range, since it can be dried in a state in which the shape of the particles is maintained, after that, by heating for a short time near the melting point of the forming material constituting the particles, Can be fused to form pores. In particular, when particles of two or more kinds of forming materials having different melting points (such as a combination of polyethylene particles and polypropylene particles) are used in combination as the particle forming material, the particles having a low melting point melt and work as a binder, The high melting point particles can be bonded to each other, and the high melting point particles and the porous film can be bonded in a state where the particle shape of the high melting point particles (high melting point particles) is maintained almost completely.

  Although the base material 1 in this invention can be manufactured by the said method, it is not limited to said example. In addition, one or both surfaces of the base material 1 may be appropriately subjected to surface treatment such as physical treatment such as corona treatment or plasma treatment, chemical treatment such as primer for the purpose of improving the adhesion of the adhesive layer 2. Also good.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2 is not particularly limited as long as the pressure-sensitive adhesive property does not change within the heat resistance range required for the lithium ion battery and does not deteriorate by the electrolyte. , Rubber adhesives, acrylic adhesives, silicone adhesives, and the like. Especially, the adhesive which has heat melting property is preferable, and an acrylic adhesive is especially preferable.

  As the acrylic pressure-sensitive adhesive, for example, it is possible to form a polymer having a relatively high Tg, giving a tackiness, a main monomer capable of forming a polymer having a relatively low glass transition point (Tg), adhesiveness and cohesion. A pressure-sensitive adhesive made of an acrylic copolymer obtained by polymerizing a monomer component such as a comonomer and a functional group-containing monomer capable of improving the formation of a crosslinking point and adhesiveness is used.

  The main monomer of the acrylic copolymer includes, for example, ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, alkyl acrylate such as octyl acrylate, and cycloacrylate acrylate such as cyclohexyl acrylate. Aralkyl esters such as alkyl esters and benzyl acrylate, alkyl methacrylates such as butyl methacrylate and 2-ethylhexyl methacrylate, cycloalkyl methacrylates such as cyclohexyl methacrylate, and aralkyl methacrylates such as benzyl methacrylate Etc. Examples of the comonomer include vinyl group-containing compounds such as methyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, vinyl propionate, vinyl ether, styrene, acrylonitrile, and methacrylonitrile.

  Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Hydroxyl group-containing monomers such as acrylate, 4-hydroxybutyl (meth) acrylate, N-methylolacrylamide, and allyl alcohol; 3 such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylaminopropyl (meth) acrylate Secondary amino group-containing monomers; Amide group-containing monomers such as acrylamide and methacrylamide; N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylic De, N- ethoxymethyl (meth) acrylamide, N-t-butyl acrylamide, N- substituted amide group-containing monomers such as N- octyl acrylamide; an epoxy group-containing monomers such as glycidyl methacrylate. These monomers can be used alone or in combination of two or more.

  By appropriately selecting the type and combination of the monomer components, an acrylic copolymer having excellent adhesiveness, cohesiveness, and durability can be obtained. Thus, the adhesive layer 2 which has arbitrary quality and characteristics according to a use can be formed by selecting suitably the polymer used as the main component of an adhesive.

  The weight average molecular weight of the polymer constituting the pressure-sensitive adhesive is not particularly limited, but is, for example, 200,000 to 1,500,000, preferably 400,000 to 1,000,000. If the molecular weight is too small, the adhesive force and cohesive force of the pressure-sensitive adhesive are inferior, and if the molecular weight is too large, the pressure-sensitive adhesive becomes hard and the adhesiveness becomes insufficient, so that the workability of sticking tends to decrease. The Tg of the polymer is not particularly limited, but is preferably −20 ° C. or lower. When Tg exceeds −20 ° C., the pressure-sensitive adhesive becomes hard depending on the use temperature, and the adhesiveness may not be maintained.

  As the pressure-sensitive adhesive, either a crosslinked type or a non-crosslinked type can be used. In the case of a crosslinking type, the pressure-sensitive adhesive may contain a crosslinking agent in addition to the polymer. As a crosslinking agent, it can select suitably according to the kind of the crosslinkable functional group which an adhesive has, for example, an epoxy-type compound, an isocyanate type compound, a metal chelate compound, a metal alkoxide, a metal salt, an amine compound, a hydrazine compound, an aldehyde System compounds and the like.

  In addition to the above, the pressure-sensitive adhesive includes an ultraviolet absorber, a tackifier, a softener (plasticizer), an anti-aging agent, a stabilizer, a filler, an anti-aging agent, a tackifier, a pigment, Additives such as dyes and silane coupling agents may be included. Examples of the tackifier include rosin and derivatives thereof, polyterpene, terpene phenol resin, coumarone-indene resin, petroleum resin, styrene resin, xylene resin and the like. Examples of the softening agent include liquid polyether, glycol ester, liquid polyterpene, liquid polyacrylate, phthalic acid ester, trimellitic acid ester, and the like.

  The main feature of the pressure-sensitive adhesive tape or sheet of the present invention is that the pressure-sensitive adhesive layer 2 is provided in a fibrous form on the substrate 1. The pressure-sensitive adhesive layer 2 is formed by, for example, a method of fiberizing a pressure-sensitive adhesive by an appropriate method such as a melt-blow method or a curtain spray method, applying and bonding this to one side of the substrate 1, and then drying or cooling. The More specifically, the fibrous adhesive is applied to the substrate while vibrating to form a nonwoven fabric-like development layer, and the development layer is pressurized to provide a nonwoven fabric-like porous adhesive layer. be able to.

  In the present invention, since the pressure-sensitive adhesive layer is provided in a fibrous form, even when the pressure-sensitive adhesive layer is disposed on the outer periphery of the element as an adhesive tape, the element can be quickly impregnated without impeding the penetration of the injected electrolyte.

  The thickness of the pressure-sensitive adhesive layer 2 is, for example, about 5 to 100 μm, preferably about 5 to 60 μm.

  The release film 3 is laminated as necessary on the pressure-sensitive adhesive layer 2 for protecting the pressure-sensitive adhesive, and a film conventionally used in the field of pressure-sensitive adhesive tapes can be used. Such a release film 3 is formed by applying a release agent such as silicone on a support made of a paper material such as glassine paper or a resin film such as polyethylene, polypropylene, or polyester using a conventional coater. It is manufactured by.

  The back surface treatment layer 4 is provided on the back surface side (base material 1 side) of the tape for the purpose of further strengthening the adhesive force to the self back surface, for example, when there is an adhesive portion with respect to the self back surface of the tape. The back treatment layer 4 is formed by applying a release treatment agent such as a long chain alkyl acrylate copolymer, a long chain alkyl vinyl ether copolymer, or a long chain alkyl vinyl ester copolymer to the back surface of the substrate. The back surface treatment layer 4 may contain the additives exemplified above in addition to the release treatment agent.

  The layer configuration of the pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element of the present invention is not limited to the above example, and at least a base material 1 made of a porous film and an adhesive on one side of the base material 1 are used. What is necessary is just to have the adhesive layer 2 provided in the fiber form.

  Examples of the method for producing a pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element according to the present invention include, for example, a method in which a pressure-sensitive adhesive is fiberized by the above-described method, and this is directly applied to one side of a substrate 1 and dried. It can be manufactured by a transfer method in which the converted adhesive is applied on a release film, dried, and transferred to a substrate. The pressure-sensitive adhesive tape or sheet obtained by the above method may be used as a lithium ion battery element winding tape as it is or in combination with other members.

  The lithium ion battery element winding adhesive tape or sheet obtained by the above method is preferably further subjected to a hydrophilic treatment. By performing the hydrophilic treatment, the permeability of the adhesive tape or sheet to the electrolytic solution can be further improved, and the injection time of the electrolytic solution can be greatly shortened. Such a hydrophilization treatment is not particularly limited as long as the affinity of the adhesive tape or sheet to the electrolytic solution is improved. For example, a surfactant impregnation treatment, hydrophilic monomer graft polymerization treatment, sulfonation Treatment, plasma treatment and the like.

  The pressure-sensitive adhesive tape or sheet of the present invention may be wound in a roll shape, or may be provided with a slit having a predetermined width.

  The lithium ion battery of the present invention is characterized in that the element is fastened with the above-described pressure-sensitive adhesive tape or sheet for winding the lithium ion battery element of the present invention. For this reason, in the electrolyte injection process, the penetration of the electrolyte solution is not hindered by the adhesive tape that surrounds the element, so that the injected electrolyte solution can quickly penetrate into the inside and impregnate the element in a short time. it can. Thus, the work efficiency of the said process improves, A lithium ion battery can be manufactured with high productivity.

In the present invention, the structure and the like of the lithium secondary battery are not particularly limited, but in general, the lithium secondary battery is composed of a positive electrode active material, a negative electrode active material, and an electrolytic solution. Examples of the positive electrode active material include manganese compounds (such as lithium manganate), manganese compounds such as manganese oxide, cobalt compounds (such as lithium cobalt oxide), cobalt compounds such as cobalt oxide, nickel oxide, and the like. Nickel compounds, iron compounds, transition metal sulfides, and the like are used. Among these, manganese-based or cobalt-based compounds are preferable. Examples of the negative electrode active material include lithium-carbon intercalation compounds such as lithium-graphite intercalation compounds, lithium-soft carbon intercalation compounds, and lithium-hard carbon intercalation compounds. Examples of the electrolytic solution include carbonate compounds such as ethylene carbonate, ethylmethyl carbonate, and propylene carbonate; ethers such as tetrahydrofuran, 4-methyldioxolane, and 1,2-dimethoxyethane; amides such as hexamethylphosphoramide; LiPF ₆ , lithium salts of fluorine-containing inorganic acids such as LiAsF ₆ and LiBF ₄ , and mixed solutions thereof. A preferable electrolytic solution includes a mixed solution of a carbonate compound and a lithium salt of a fluorine-containing inorganic acid.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The porosity of the porous film was adjusted by controlling the conditions for producing the porous film (the method for forming pores and the conditions thereof).

Example 1
90 parts by weight of butyl acrylate and 10 parts by weight of acrylic acid are used as monomer components on one side of a 50 μm-thick ultrahigh molecular weight polyethylene porous film (porosity 50%, Mw 500,000) obtained by the above method. An acrylic pressure-sensitive adhesive composition comprising 100 parts by weight of an acrylic ester copolymer [weight average molecular weight (Mw) 500,000] and 1 part by weight of trimethylolpropane tolylene diisocyanate (crosslinking agent) having a diameter of 50 μm Using an extruder equipped with a nozzle having a discharge hole, the nozzle is extruded while swinging left and right with a width of 10 mm, and a non-woven spread layer (apparent thickness) made of a fibrous adhesive having an outer diameter of about 20 μm About 35 μm). This spreading layer was pressed at a pressure of 5 kg / cm ² to obtain a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer (apparent thickness 30 μm) composed of a non-woven porous structure.
A mixture of 100 parts by weight of a cellulose acetate polymer (Mw 500,000) and 30 parts by weight of a long-chain alkyl acrylate polymer (release component) is applied to the surface of the base material of the obtained adhesive tape, and the thickness is less than 1 μm. The back treatment layer was provided.
Next, a release film having a thickness of 38 μm (a transparent polyester film treated with silicone on one side) is laminated on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape to laminate the release film, and the pressure-sensitive adhesive tape having the structure shown in FIG. Produced.

Example 2
In Example 1, instead of an ultrahigh molecular weight polyethylene porous film (porosity 50%, Mw 500,000) as a substrate, a fluorine-containing porous film having a thickness of 50 μm (corona treatment on both sides; porosity 50%) An adhesive tape was obtained by performing the same operation as in Example 1 except that [manufactured by Nitto Denko Corporation] was used.

Example 3
In Example 1, an ultra high molecular weight polyethylene porous film (porosity 10%, Mw 500,000) was used instead of an ultra high molecular weight polyethylene porous film (porosity 50%, Mw 500,000) as a base material. A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1.

Example 4
In Example 1, an ultra high molecular weight polyethylene porous film (porosity 80%, Mw 500,000) was used instead of an ultra high molecular weight polyethylene porous film (porosity 50%, Mw 500,000) as a base material. A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1.

Example 5
In Example 1, the adhesive tape was obtained by the method similar to Example 1 except having used the acrylic ester copolymer (Mw1.3 million) instead of the acrylic ester copolymer (Mw500,000).

Example 6
In Example 1, as an adhesive, instead of an acrylic adhesive composition, natural rubber (adhesive component) 100 parts by weight, terpene resin (tackifier resin) 40 parts by weight, petroleum resin (tackifier resin) A pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that a rubber-based pressure-sensitive adhesive composition comprising 30 parts by weight and an anti-aging agent (trade name “Sumilyzer NW”, manufactured by Sumitomo Chemical Co., Ltd.) was used. Got.

Example 7
In Example 1, an adhesive tape was obtained by the same method as in Example 1 except that the back treatment layer was not provided.

Example 8
In Example 1, an adhesive tape was obtained by the same method as in Example 1 except that the release film was not used.

Comparative Example 1
In Example 1, the same as Example 1 except that a polyimide film (thickness 25 μm, manufactured by Toray DuPont Co., Ltd.) was used instead of the ultrahigh molecular weight polyethylene porous film (porosity 50%) as the base material. The adhesive tape was obtained by the method.

Comparative Example 2
In Example 1, a polyethylene terephthalate film (thickness 25 μm; trade name “Lumirror S-10”, manufactured by Toray Industries, Inc.) is used as a substrate instead of an ultrahigh molecular weight polyethylene porous film (porosity 50%). A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that.

Comparative Example 3
In Example 1, a polypropylene film (thickness 25 μm; trade name “Trephan”, manufactured by Toray Industries, Inc.) was used in place of the ultrahigh molecular weight polyethylene porous film (porosity 50%) as the base material. Obtained the adhesive tape by the method similar to Example 1. FIG.

Comparative Example 4
In Example 1, an ultra high molecular weight polyethylene porous film (porosity 0%, Mw 500,000) was used instead of an ultra high molecular weight polyethylene porous film (porosity 50%, Mw 500,000) as a substrate. A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1.

Evaluation Test The following evaluations were performed on the adhesive tapes obtained in Examples and Comparative Examples, and the results are shown in Table 1. In Table 1, “porosity” indicates the porosity of the substrate used for the adhesive tape.
(Adhesiveness)
What wound the adhesive tape obtained by the Example and the comparative example on the cylinder was immersed in ethylene glycol electrolyte solution, and the peeling property of the tape was evaluated visually. When there was no peeling of the winding part, it was evaluated as “◯”, and when there was peeling off, it was evaluated as “x”, and the results are shown in Table 1.
(Penetration)
Each adhesive tape obtained in Examples and Comparative Examples was cut to a size of 10 mm × 10 mm to obtain a tape sample, and the weight was measured.
Each of the above tape samples is taken out by immersing in ethylene glycol as an electrolytic solution for 30 seconds, and after the surface drops are blown off with air, the weight of the tape is immediately measured to determine the increased weight, and the value is divided by the tape volume. The numerical value obtained was taken as the amount of electrolyte solution impregnation. The obtained results are shown in the column of “Penetration” in Table 1.

  As shown in Table 1, each of the adhesive tapes of Examples 1 to 8 can be impregnated with a sufficient amount of electrolytic solution with an immersion time of 30 seconds. It has adhesiveness to wind the element. On the other hand, in each of the adhesive tapes of Comparative Examples 1 to 3, since the amount of the electrolyte solution impregnated in 30 seconds is low, there is no characteristic that shortens the electrolyte injection time, and the adhesive tape of Comparative Example 4 is sufficient. Although it was possible to impregnate a sufficient amount of the electrolytic solution, it was confirmed that it did not have adhesiveness to wind the element.

It is the schematic sectional drawing which showed an example of the adhesive tape for lithium ion battery element winding of this invention.

Explanation of symbols

1 Porous film (base material)
2 Adhesive layer
3 Release film
4 Back treatment layer
5 pores

Claims (4)

A pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element, comprising a base material composed of a porous film and a pressure-sensitive adhesive layer provided on one side of the base material in a fibrous form. The pressure-sensitive adhesive tape or sheet for winding a lithium ion battery element according to claim 1, wherein the substrate is composed of a porous film having a porosity of 10 to 80%. The adhesive tape or sheet for lithium ion battery element winding of Claim 1 or 2 with which the base material is comprised with the porous film which has heat resistance. The lithium ion battery by which the element is wound with the adhesive tape or sheet | seat for lithium ion battery element winding of any one of Claims 1-3.

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