Metal foil laminate for current collector layer

Abstract

The present invention addresses the problem of providing a metal foil laminate which can maintain appropriate strength and electrolyte resistance and which can be reduced in weight. [Solution] A laminate having a resin layer formed from a resin composition containing (A) a cycloolefin polymer, and metal foil layers formed on both surfaces of the resin layer.

Description

Technical Field

[0001] The present invention relates to a metal foil laminate for use as a current collecting layer. Background Art

[0002] In 5G and Beyond 5G, as the number of devices assembled in the device increases, there is a tendency for the weight and size of the batteries driving them to become heavier and larger. Therefore, it is expected to reduce the weight while ensuring a certain current. For example, for HAPS and electric vehicles EV that fly in the stratosphere and provide wireless communication services on the ground with solar cell panels and batteries, weight reduction is required, so it is necessary to lightweight the electrodes used in the battery. The demand is met by reducing the thickness of the metal foil used as the collector layer, but there is a technical limit to the thin filmization of metal foil. Ultra-thin metal foil is prone to wrinkles and pinholes, making it difficult to apply to the production process.

[0003] Furthermore, if the metal foil is made thinner, the weight can be reduced, but the strength is reduced. Therefore, it is preferable that the metal foil has a strength that can withstand the battery production process.

[0004] For example, Patent Document 1 discloses a metal foil laminate for a current collecting layer having a resin layer formed from a cured product of a resin composition containing a thermosetting resin, a thermoplastic resin, and a curing agent, and metal foil layers formed on both surfaces of the resin layer.

[0005] However, practical lithium-ion secondary batteries often use lithium hexafluorophosphate, ethylene carbonate, dimethyl carbonate, and other solvents as their electrolytes. Ethylene carbonate, in particular, is a highly polar organic solvent with a high solubility for resins, so resins that can withstand this electrolyte must be selected.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application No. 2023-027749 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a metal foil laminate that can achieve weight reduction while maintaining appropriate strength and electrolyte resistance.

[0011] Solutions for solving problems

[0012] As a result of in-depth research conducted by the present inventors to solve the above-mentioned problems, they found that in a laminate having a resin layer formed from a resin composition and a metal foil layer formed on both sides of the resin layer, by using a cycloolefin polymer as a resin constituting the resin composition, a metal foil laminate can be obtained that can maintain appropriate strength and electrolyte resistance and achieve lightweight, thereby completing the present invention.

[0013] That is, the present invention has the following features.

[0014] [1] A laminate comprising a resin layer formed from a resin composition containing a cycloolefin polymer (A) and metal foil layers formed on both surfaces of the resin layer.

[0015] [2] The laminate according to [1], wherein the (A) cycloolefin polymer comprises at least one cycloolefin copolymer.

[0016] [3] The laminate according to [1] or [2], wherein the content of the (A) cycloolefin polymer in the resin composition is 50 to 100% by mass relative to 100% by mass of the non-volatile components of the resin composition.

[0017] [4] The laminate according to any one of [1] to [3], wherein the resin composition further contains (B) a styrene-based thermoplastic elastomer.

[0018] [5] The laminate according to [4], wherein the content of the repeating units having a reactive group in the repeating units constituting the styrene-based thermoplastic elastomer (B) is 0 to 3% by mass relative to the total mass of the styrene-based thermoplastic elastomer (B).

[0019] [6] The laminate according to [4] or [5], wherein the weight average molecular weight of the styrene-based thermoplastic elastomer (B) exceeds 50,000.

[0020] [7] The laminate according to any one of [4] to [6], wherein the content of the (B) styrene-based thermoplastic elastomer in the resin composition is 5 to 20% by mass relative to 100% by mass of the non-volatile components of the resin composition.

[0021] [8] The laminate according to any one of [1] to [7], wherein the resin composition further contains (C) a conductive filler.

[0022] [9] The laminate according to [8], wherein the content of the conductive filler (C) in the resin composition is 0.5 to 10% by mass relative to 100% by mass of the non-volatile components of the resin composition.

[0023]

[10] The laminate according to any one of [1] to [9], wherein the metal foil layer is a copper foil layer.

[0024]

[11] The laminate according to any one of [1] to

[10] , wherein the thickness of the resin layer is 3 to 60 μm.

[0025]

[12] The laminate according to any one of [1] to

[11] , wherein the Young's modulus is 10,000 MPa or more.

[0026]

[13] The laminate according to any one of [1] to

[12] , wherein the elongation ratio is 1.2 or more.

[0027] Effects of the Invention

[0028] According to the present invention, compared with the case where the current collecting layer is made of metal foil alone, a metal foil laminate can be provided that is lightweight and has appropriate strength and electrolyte resistance. In addition, according to the present invention, the current collecting layer can be freely designed by adjusting the thickness of the metal foil layer and the resin layer, imparting conductivity to the resin layer, etc. DETAILED DESCRIPTION

[0029] Hereinafter, the present invention will be described according to preferred embodiments thereof.

[0030] [Laminated body]

[0031] The laminate of the present invention comprises a resin layer formed from a resin composition containing a cycloolefin polymer (A) and metal foil layers formed on both surfaces of the resin layer.

[0032] <(A) Cycloolefin Polymer>

[0033] The cycloolefin polymer (sometimes referred to as " COP " in this specification) used in the resin composition of the present invention is a polymer having a structural unit derived from cyclic olefins on one or both sides of the main chain and the side chain. Cycloolefin polymer can be a homopolymer or a copolymer. Cycloolefin polymer can only use one or more than two kinds. By using cycloolefin polymer, it is possible to obtain a laminate maintaining appropriate intensity and electrolyte resistance, and can be used as a current collecting layer excellent in intensity and electrolyte resistance.

[0034] The cyclic olefin is not particularly limited as long as it can exhibit the effects of the present invention, and may be a polycyclic cyclic olefin or a monocyclic cyclic olefin.

[0035] The polycyclic cyclic olefin is not particularly limited as long as it exhibits the effects of the present invention, and examples thereof include norbornene compounds such as norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidenenorbornene, and butylnorbornene; dicyclopentadiene compounds such as dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, and dimethyldicyclopentadiene; tetracyclododecene, methyltetracyclododecene, dimethyltetracyclododecene; tricyclopentadiene; and tetracyclopentadiene.

[0036] The monocyclic cyclic olefin is not particularly limited as long as it can exhibit the effects of the present invention, and examples thereof include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene, and cyclododecatriene.

[0037] From the viewpoint of forming the resin composition into a film (forming a resin layer), the weight average molecular weight of the cycloolefin polymer is preferably 5000 to 1000000, more preferably 8000 to 200000. It should be noted that the weight average molecular weight is measured using gel permeation chromatography (GPC) (converted to polystyrene). Specifically, the weight average molecular weight based on the GPC method can be calculated as follows: using LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, using Shodex K-800P / K-804L / K-804L manufactured by Showa Denko as a column, using chloroform etc. as a mobile phase, measuring at a column temperature of 40°C, and calculating using a standard curve of standard polystyrene.

[0038] Examples of commercially available cycloolefin polymers include "ZEONOR" manufactured by ZEON Corporation of Japan and "ARTON" manufactured by JSR Corporation.

[0039] The cycloolefin polymer used in the resin composition of the present invention is preferably a cycloolefin copolymer (sometimes referred to as "COC" in this specification) from the viewpoint of flexibility. Cyclic olefin copolymer refers to a polymer having constituent units derived from the above-mentioned cyclic olefin and constituent units derived from non-cyclic olefins such as ethylene and α-olefins. The cycloolefin copolymer may be any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer. As the cycloolefin copolymer, a polymer having constituent units derived from a norbornene compound and constituent units derived from ethylene is preferred. Only one cycloolefin copolymer may be used, or two or more cycloolefin copolymers may be used in combination.

[0040] The α-olefins are not particularly limited as long as they exhibit the effects of the present invention. Examples thereof include linear α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene; and branched α-olefins having 4 to 20 carbon atoms, such as 4-methyl-1-pentene, 3-methyl-1-pentene, and 3-methyl-1-butene.

[0041] The proportion of polymerized units derived from cyclic olefins, particularly polycyclic cyclic olefins, is preferably 3 to 75 mol% based on the total structure of the cyclic olefin copolymer. The proportion of polymerized units derived from acyclic olefins is preferably 5 to 80 mol% based on the total structure of the cyclic olefin copolymer.

[0042] Examples of commercially available cycloolefin copolymers include "TOPAS" manufactured by Polyplastics (a cycloolefin copolymer obtained by copolymerizing norbornene and ethylene) and "APEL" manufactured by Mitsui Chemicals (a cycloolefin copolymer obtained by copolymerizing norbornene and ethylene).

[0043] From the viewpoint of the strength of the resin layer, the content of the cycloolefin polymer in the resin composition of the present invention is preferably 50 to 100 mass %, more preferably 60 to 100 mass %, and even more preferably 65 to 100 mass % relative to 100 mass % of the nonvolatile components of the resin composition.

[0044] <(B) Styrene-based thermoplastic elastomer>

[0045] Resin combination of the present invention, as long as in the scope that can bring into play effect of the present invention, just also can further comprise styrene-based thermoplastic elastomer.Styrene-based thermoplastic elastomer can only use 1 kind, also can use more than 2 kinds.By using styrene-based thermoplastic elastomer, can obtain keeping suitable flexibility and electrolyte resistance laminate, can be used as the excellent current collecting layer of flexibility and electrolyte resistance and use.

[0046] The styrene-based thermoplastic elastomer is not particularly limited as long as it can exhibit the effects of the present invention, and examples thereof include polystyrene-poly(ethylene-butylene)-polystyrene triblock copolymer (SEBS), polystyrene-polyisobutylene-polystyrene block copolymer (SIBS), polystyrene-polyisobutylene block copolymer (SIB), polystyrene-poly(ethylene-propylene) block copolymer (SEP), polystyrene-poly(ethylene-propylene)-polystyrene triblock copolymer (SEPS), and polystyrene-poly(ethylene / ethylene-propylene)-polystyrene triblock copolymer (SEEPS).

[0047] Examples of commercially available styrene-based thermoplastic elastomers include the "TUFTEC M series" (maleic acid-modified SEBS) manufactured by Asahi Kasei Corporation, the "TUFTEC H series" (SEBS) manufactured by Asahi Kasei Corporation, the "SIBSTAR series" (SIBS, SIB) manufactured by Kaneka Corporation, and the "SEPTON series" (SEP, SEPS, SEEP, SEBS) manufactured by Kuraray Co., Ltd.

[0048] From the viewpoint of electrolyte resistance, the content of the repeating unit having a reactive group in the repeating units constituting the styrene-based thermoplastic elastomer is preferably 0 to 20% by mass, more preferably 0 to 15% by mass, further preferably 0 to 10% by mass, and most preferably 0% by mass, relative to the total mass of the styrene-based thermoplastic elastomer.

[0049] From the viewpoint of heat resistance and electrolyte resistance, the weight average molecular weight of the styrene-based thermoplastic elastomer is preferably more than 50,000 and less than 500,000, more preferably more than 70,000 and less than 400,000, and further preferably more than 100,000 and less than 300,000. It should be noted that the weight average molecular weight is measured by gel permeation chromatography (GPC) method (converted into polystyrene). Specifically, the weight average molecular weight based on the GPC method can be calculated as follows: using LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, using Shodex K-800P / K-804L / K-804L manufactured by Showa Denko as a column, using chloroform or the like as a mobile phase, measuring at a column temperature of 40°C, and calculating using a standard curve of standard polystyrene.

[0050] From the viewpoint of heat resistance and electrolyte resistance, the content of the styrene units in the repeating units constituting the styrene-based thermoplastic elastomer is preferably 10 to 50% by mass, more preferably 11 to 45% by mass, and even more preferably 12 to 40% by mass relative to the total mass of the styrene-based thermoplastic elastomer. In addition, repeating units other than the styrene units are preferably hydrogenated when having unsaturated bonds.

[0051] From the viewpoint of the strength of the resin layer, the content of the styrene-based thermoplastic elastomer in the resin composition of the present invention is preferably 5 to 20% by mass, more preferably 5 to 10% by mass, relative to 100% by mass of the nonvolatile components of the resin composition.

[0052] <(C) Conductive filler>

[0053] In the resin combination of the present invention, in order to improve the electrical conductivity of the laminate, a conductive filler can be further contained. As a conductive filler, for example, carbon black, graphite, carbon nanotubes, metal powders (nickel, aluminum, stainless steel (SUS), silver, copper, zinc and titanium, etc.), metal oxide powders (tin oxide, indium oxide and zinc oxide, etc.), metal coating powders (inorganic materials and organic materials coated with conductive materials, etc.) etc. can be enumerated. From the viewpoint of lightweight, preferably carbon black. As carbon black, preferably acetylene black, oil furnace carbon black, gas furnace carbon black, lamp black, channel carbon black etc. Specific examples of carbon black include Raven 760 ULTRA, Raven 780 ULTRA, Raven 790 ULTRA, Raven 1060 ULTRA, Raven 1080 ULTRA, Raven 1170, Raven 1190 ULTRA II, Raven 1200, Raven 1250, Raven 1255, Raven 1500, Raven 2000, Raven 2500 ULTRA, Raven 3500, Raven 5000 ULTRA II, Raven 5250, Raven 5750, and Raven 7000 (all manufactured by Columbia Carbon Co., Ltd.); Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, Regal 1330R, Regal 1400R, Regal 1660R, and Mogul L (all manufactured by Cabot Corporation); Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 4, Special Black 4A, Special Black 5, Special Black 6 (all manufactured by Degussa Corporation); MA7, MA8, MA100, MA600, MCF-88, No.25, No.33, No.40, No.47, No.52, No.900, No.2300 (all manufactured by Mitsubishi Chemical Corporation); etc. Examples of carbon nanotubes include single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs), as well as multi-walled carbon nanotubes (MWCNTs).The conductive filler may be used alone or in combination of two or more.

[0054] For the particle size of the conductive filler, from the viewpoint of forming the resin composition into a film (forming a resin layer), the particle size of the primary particles is preferably 5 μm or less, more preferably 3 μm or less. For example, a filler having a particle size of 0.001 to 3 μm can be used as the primary particle, and a filler having a particle size of 0.005 to 2 μm as the primary particle can be more preferably used. It should be noted that in the present invention, "particle size" can be measured using a laser diffraction particle size distribution meter (JIS Z 8825) or a dynamic light scattering method (JIS Z 8828) or an image analysis method (JIS Z 8827).

[0055] From the viewpoint of conductivity and dispersibility, the content of the conductive filler in the resin composition of the present invention is preferably 0.5 to 35% by mass, more preferably 1 to 25% by mass, and even more preferably 3 to 20% by mass relative to 100% by mass of the non-volatile components of the resin composition. In other embodiments of the present invention, the content of the conductive filler in the resin composition is preferably 0.5 to 10% by mass relative to 100% by mass of the non-volatile components of the resin composition.

[0056] <Other additives>

[0057] The resin composition of the present invention may further contain additives other than the above-mentioned components, as long as they can achieve the effects of the present invention. Examples of such additives include silane coupling agents; organic fillers such as rubber particles, silicone powder, nylon powder, and fluororesin powder; thickeners such as Orben and Benton; silicone-based, fluorine-based, or polymer-based defoamers or leveling agents; adhesion-imparting agents such as triazole compounds, thiazole compounds, triazine compounds, and porphyrin compounds; and flame retardants such as phosphorus compounds and metal hydroxides.

[0058] <Method for producing resin composition>

[0059] The method for producing the resin composition of the present invention is not particularly limited, and examples thereof include a method in which a solvent or the like is added as needed and the above-mentioned components are mixed using a kneading roll, a rotary mixer, or the like.

[0060] <Resin Layer>

[0061] In the laminate of the present invention, the resin layer is formed from the resin composition described above. The resin layer can be formed on the support by, for example, applying a varnish-like resin composition mixed with an organic solvent to one surface of the support and drying the resulting coating by heating or blowing hot air.

[0062] Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone (sometimes referred to as "MEK" in this specification), and cyclohexanone; acetates such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aliphatic hydrocarbons such as methylcyclohexane; aromatic hydrocarbons such as toluene and xylene; dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Any one of the organic solvents may be used alone, or two or more may be used in combination.

[0063] As the support, there can be mentioned plastic films such as polyethylene, polypropylene, polyvinyl chloride and other polyolefins, cycloolefin polymers, polyethylene terephthalate (sometimes referred to as "PET" in this specification), polyethylene naphthalate and other polyesters, polycarbonate, polyimide and the like. As the plastic film, PET is particularly preferred. In addition, the support may also be a metal foil such as aluminum foil, stainless steel foil, copper foil, etc. For the support, a release treatment, matte treatment, corona treatment, etc. using a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, etc. may also be implemented on the surface where the resin layer is formed. In the present invention, when the support has a release layer, the release layer is also regarded as a part of the support. The thickness of the support is not particularly limited, but from the viewpoint of operability, etc., it is preferably 20 to 200 μm, more preferably 20 to 125 μm.

[0064] The drying conditions are not particularly limited, but drying at about 50 to 100° C. for about 3 to 15 minutes is usually appropriate.

[0065] From the perspective of lightweighting and electrical resistance, the thickness of the resin layer is preferably 60 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less. From the perspective of layer formation, the lower limit of the thickness of the resin layer is preferably 3 μm or more, more preferably 5 μm or more. In one embodiment of the present invention, the thickness of the resin layer is preferably 3 to 60 μm, more preferably 5 to 50 μm.

[0066] <Metal foil layer>

[0067] In the laminate of the present invention, a metal foil layer is formed on both sides of the resin layer. Examples of metals include copper, nickel, aluminum, stainless steel (SUS), silver, and titanium. From the perspective of durability to the electrolyte, copper and nickel are preferred. The method for forming the metal foil layer is not particularly limited, and known techniques, such as wet film-forming methods such as electroless copper plating and electrolytic copper plating, dry film-forming methods such as sputtering and chemical vapor deposition, and combinations thereof, can be used. In addition, when a metal foil layer is formed on a resin layer by vapor deposition, etc., in the event of damage caused by heat during the process, the shrinkage and wrinkling of the resin layer can be suppressed by laminating a removable micro-adhesive PET film (for example, a laminate having a laminate structure of resin layer / micro-adhesive PET film, resin layer / support / micro-adhesive PET film, etc., is produced, and a metal foil layer is formed on the resin layer). From the viewpoint of weight reduction and electrical resistance, the thickness of the metal foil layer is preferably 0.005 to 2 μm, more preferably 0.01 to 1.5 μm, and even more preferably 0.02 to 1 μm.

[0068] From the perspective of the strength of the resin layer, the Young's modulus of the laminate of the present invention is preferably 10,000 MPa or more, more preferably 12,500 MPa or more, further preferably 15,000 MPa or more, and preferably 40,000 MPa or less, more preferably 35,000 MPa or less, and further preferably 30,000 MPa or less. By setting the Young's modulus to the above range, a laminate maintaining appropriate strength can be obtained. If the Young's modulus is less than 10,000 MPa, the tensile stress and rigidity become too low, resulting in problems such as the resin layer being easily broken and the overall strength of the layer being reduced. On the other hand, if the Young's modulus exceeds 40,000 MPa, the tensile stress and rigidity become too high, resulting in problems such as the resin layer being easily broken and the overall strength of the layer being reduced. It should be noted that the Young's modulus in the present invention is a value measured at 23°C in accordance with JIS K7127.

[0069] The laminate of the present invention preferably has an elongation ratio of 1.2 to 20, and more preferably 1.5 to 15, from the viewpoint of strength and flexibility of the resin layer. The elongation ratio in the present invention is a value calculated by the following formula.

[0070] Elongation ratio = elongation at break of resin layer / elongation at break of copper foil layer

[0071] If the elongation ratio is less than 1.2, the elongation at break of the copper foil layer becomes too high relative to that of the resin layer, resulting in problems such as the resin layer being prone to breaking first, a decrease in overall layer strength, concerns about interlayer delamination, and deterioration in workability. On the other hand, if the elongation ratio exceeds 20, the elongation at break of the resin layer becomes too high relative to that of the copper foil layer, resulting in problems such as the copper foil layer being prone to breaking first, a decrease in overall layer strength, concerns about interlayer delamination, and deterioration in durability. The elongation at break is measured at 23°C in accordance with JIS K7127.

[0072] [Method for producing laminate]

[0073] The method for manufacturing the laminate of the present invention is not particularly limited. For example, the following method can be cited: a resin layer is formed on a support as described in the above-mentioned item <Resin layer>, a protective film is laminated on the surface of the resin layer on the opposite side of the support as needed to obtain a sheet, and then a metal foil layer is formed on the resin layer (exposed by peeling off the protective film as needed) as described in the above-mentioned item <Metal foil layer>, and then a metal foil layer is similarly formed on the resin layer exposed by peeling off the support.

[0074] As the protective film, there can be mentioned plastic films such as polyethylene, polypropylene, polyvinyl chloride and other polyolefins, cycloolefin polymers, PET, polyethylene naphthalate and other polyesters, polycarbonate, polyimide and the like. As the plastic film, PET is particularly preferred. In addition, the protective film may also be a metal foil such as aluminum foil, stainless steel foil, copper foil and the like. For the protective film, a release treatment using a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent and the like, a matte treatment, a corona treatment and the like may also be applied on the surface in contact with the resin layer. In the present invention, when the protective film has a release layer, the release layer is also regarded as a part of the protective film. The thickness of the protective film is not particularly limited, but is preferably 20 to 200 μm, more preferably 20 to 125 μm, from the viewpoint of operability and the like.

[0075] [use]

[0076] The laminate of the present invention can be suitably used, for example, as a current collecting layer, particularly as a current collecting layer of a negative electrode of a battery.

[0077] Example

[0078] The present invention will be described in more detail below with reference to Examples. However, the present invention is not limited to the following Examples and can be implemented with appropriate modifications within the scope of the above and below-described gist, all of which are encompassed by the technical scope of the present invention. It should be noted that, unless otherwise specified, "parts" and "%" in the amounts of components and copolymerized units refer to "parts by mass" and "% by mass," respectively.

[0079] <Ingredients>

[0080] The components used in Examples and Comparative Examples are shown below.

[0081] (A) Cyclic olefin polymer:

[0082] Cyclic olefin copolymer ("TOPAS 8007F" manufactured by Polyplastics; COC obtained by copolymerization of norbornene and ethylene)

[0083] Cyclic olefin copolymer ("TOPAS 5013L" manufactured by Polyplastics; COC obtained by copolymerization of norbornene and ethylene)

[0084] Cyclic olefin copolymer ("APEL 6011T" manufactured by Mitsui Chemicals; COC obtained by copolymerization of norbornene and ethylene)

[0085] Cyclic olefin copolymer ("APEL 5014CL" manufactured by Mitsui Chemicals; COC obtained by copolymerization of norbornene and ethylene)

[0086] (B) Styrene-based thermoplastic elastomer:

[0087] Maleic acid-modified SEBS ("TUFTEC M1911" manufactured by Asahi Kasei Corporation, weight-average molecular weight: 82,000)

[0088] SEBS ("TUFTEC H1043" manufactured by Asahi Kasei Corporation, weight average molecular weight: 141,000)

[0089] SIBS ("SIBSTAR 103T-UL" manufactured by Kaneka Corporation, weight average molecular weight: 70,000)

[0090] (C) Conductive filler:

[0091] Carbon black (average particle size 50 nm (measured by image analysis (JIS Z 8827)), "#20" manufactured by Mitsubishi Chemical Corporation)

[0092] Carbon nanotubes (OCSiA1 "TUBALL615", carbon nanotube content 10%)

[0093] Others (Comparative Example ingredients):

[0094] A mixture of liquid bisphenol A epoxy resin and liquid bisphenol F epoxy resin ("ZX-1059" manufactured by Nippon Steel Chemicals & Materials Co., Ltd., epoxy equivalent: approximately 165 g / eq)

[0095] Phenoxy resin solution ("YX7200B35" manufactured by Mitsubishi Chemical Corporation, solvent: MEK, non-volatile content: 35%, epoxy equivalent: approximately 8000 g / eq)

[0096] "2E4MZ" (curing agent) manufactured by Shikoku Chemical Industry Co., Ltd.

[0097] San-Apro's "U-CAT3512T" (curing accelerator)

[0098] Salicylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.; curing accelerator)

[0099] <Example 1>

[0100] Varnishes with the blending ratios shown in the table below were prepared according to the following procedure, and laminates were produced using the resulting varnishes. The amounts (parts) of the components listed in the table below represent the amount of non-volatile components in the varnish. Specifically, 50 parts of a cycloolefin copolymer ("8007F" manufactured by Polyplastics) was added. Toluene was added as a solvent to prepare a 30% non-volatile solution for uniform coating, and the resulting solution was uniformly dispersed using a high-speed rotary mixer to produce a varnish.

[0101] The obtained varnish was evenly coated on the release-treated surface of a support (polyethylene terephthalate film treated with a silicone-based release agent, 38 μm thick, hereinafter referred to as "release PET film") using a die coater in such a manner that the thickness of the resin layer after drying became 10 μm. After drying at 120°C for 10 minutes, a release PET film as a protective film was attached to the surface of the formed resin layer in such a manner that the release-treated surface thereof was in contact with the resin layer, thereby obtaining a sheet having a laminated structure of support / resin layer / protective film.

[0102] The protective film of the obtained sheet is peeled off, and a copper foil layer (thickness: 0.2 μm) is formed on the exposed resin layer by vapor deposition. Then, the support is peeled off, and a copper foil layer (thickness: 0.2 μm) is similarly formed on the exposed resin layer to produce a laminate having a laminate structure of copper foil layer / resin layer / copper foil layer.

[0103] <Example 2>

[0104] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was prepared using the same method as in Example 1, except that 25 parts of cycloolefin copolymer ("5013L" manufactured by Polyplastics) and 25 parts of cycloolefin copolymer ("6011T" manufactured by Mitsui Chemicals) were used instead of cycloolefin copolymer ("8007F" manufactured by Polyplastics).

[0105] <Example 3>

[0106] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was produced by the same method as in Example 1 except that 5 parts of maleic acid-modified SEBS ("M1911" manufactured by Asahi Kasei Corporation) was further blended.

[0107] <Example 4>

[0108] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was produced by the same method as in Example 1 except that 10 parts of maleic acid-modified SEBS ("M1911" manufactured by Asahi Kasei Corporation) was further blended.

[0109] <Example 5>

[0110] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was produced by the same method as in Example 1 except that 5 parts of SEBS ("H1043" manufactured by Asahi Kasei Corporation) was further blended.

[0111] <Example 6>

[0112] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was produced by the same method as in Example 1 except that 5 parts of SIBS ("103T-UL" manufactured by Kaneka Corporation) was further blended.

[0113] <Example 7>

[0114] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was prepared using the same method as in Example 1, except that 50 parts of cycloolefin copolymer ("5014CL" manufactured by Mitsui Chemicals, Inc.) was used instead of cycloolefin copolymer ("8007F" manufactured by Polyplastics Co., Ltd.) and 2.5 parts of carbon black (average particle size 50 nm, "#20" manufactured by Mitsubishi Chemical Corporation) was further blended.

[0115] <Example 8>

[0116] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was prepared by the same method as in Example 1, except that 50 parts of cycloolefin copolymer ("5014CL" manufactured by Mitsui Chemicals, Inc.) was used instead of cycloolefin copolymer ("8007F" manufactured by Polyplastics Co., Ltd.) and 50 parts of carbon black (average particle size 50 nm, "#20" manufactured by Mitsubishi Chemical Corporation) was further mixed.

[0117] <Example 9>

[0118] A laminate having a laminate structure of copper foil layer / resin layer / copper foil layer was produced in the same manner as in Example 1 except that 5 parts of carbon nanotubes ("TUBALL 615" manufactured by OCSiA1, carbon nanotube content 10%) were further blended.

[0119] <Comparative Example 1>

[0120] A commercially available copper foil (thickness 5 μm) was used instead of the laminate having a laminate structure of copper foil layer / resin layer / copper foil layer.

[0121] <Comparative Example 2>

[0122] A commercially available PET film (thickness 5 μm) was used instead of the laminate having a laminate structure of copper foil layer / resin layer / copper foil layer.

[0123] <Comparative Example 3>

[0124] A mixture of 80 parts of a liquid bisphenol A epoxy resin and a liquid bisphenol F epoxy resin ("ZX-1059" manufactured by Nippon Steel Chemicals & Materials Co., Ltd.) and 120 parts of a phenoxy resin solution ("1256B40" manufactured by Mitsubishi Chemical Corporation) was mixed and uniformly dispersed using a high-speed rotary mixer to obtain a mixture. Furthermore, 5 parts of a curing accelerator ("U-CAT3512T" manufactured by San-Apro), 0.5 parts of a curing accelerator ("salicylic acid" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 2 parts of a curing agent ("2E4MZ" manufactured by Shikoku Chemicals Co., Ltd.) were mixed and uniformly dispersed using a high-speed rotary mixer to obtain a varnish of the resin composition.

[0125] The obtained varnish was uniformly coated on a support (polyethylene terephthalate film treated with a non-silicone release agent, thickness 38 μm, hereinafter referred to as “release PET film”) using a die coater in such a manner that the thickness of the resin composition layer after drying became 10 μm. After drying at 80°C for 10 minutes, a release PET film as a protective film was attached to the surface of the formed resin composition layer in such a manner that its release-treated surface was in contact with the resin composition layer, thereby obtaining a sheet having a laminated structure of support / resin composition layer / protective film.

[0126] The protective film of the obtained sheet was peeled off, and a copper foil with a carrier (carrier: PET; thickness: 38 μm; copper foil thickness: 0.2 μm) was laminated on the exposed resin composition layer. Then, the support was peeled off, and a copper foil with a carrier (carrier: PET; thickness: 38 μm; copper foil thickness: 0.2 μm) was laminated on the exposed resin composition layer. The mixture was heated and pressed under conditions of 80°C and 0.3 MPa, and heated in an oven at 100°C for 60 minutes to thermally cure the resin composition layer to produce a laminate having a laminate structure of copper foil layer / resin layer / copper foil layer.

[0127] The laminates, copper foils, and PET films obtained in Examples and Comparative Examples were evaluated by the following methods.

[0128] <Evaluation of film properties>

[0129] The states of the laminates obtained in Examples and Comparative Examples were determined as follows.

[0130] ○ (good): The film (resin layer) is well formed and can be used as a current collecting layer

[0131] × (bad): A film (resin layer) can be formed, but the viscosity is strong and cannot be used as a collector layer; or a film (resin layer) can be formed, but the adhesion to the copper foil layer is weak and cannot be used as a collector layer; or a film cannot be formed

[0132] <Weight evaluation>

[0133] The laminates, copper foils, and PET films obtained in Examples and Comparative Examples were cut into 5 cm squares, and the weights were measured using a precision balance to calculate the weight per unit area.

[0134] ○ (good): Weight per unit area is less than 5 mg / cm 2

[0135] × (bad): weight per unit area is 5 mg / cm 2 above

[0136] <Evaluation of resistance value>

[0137] The laminates, copper foils, and PET films obtained in Examples and Comparative Examples were cut into 5 cm squares, and their surface resistance values ​​were measured using a low-resistivity meter (MCP-T700, manufactured by Mitsubishi Chemical Analytech) using a four-probe method.

[0138] ○(Good): Resistance value is less than 1Ω / mouth

[0139] × (bad): Unable to measure due to resistance value of 1Ω / Ω or higher or high resistance

[0140] <Evaluation of Electrolyte Resistance>

[0141] The laminates, copper foil, and PET film obtained in the Examples and Comparative Examples were cut into 5 cm squares, and their initial weights were measured using a precision balance. A container containing dimethyl carbonate was prepared, and the laminate, copper foil, and PET film were immersed in the dimethyl carbonate and allowed to sink for 24 hours. After this period, the laminate, copper foil, and PET film were removed, the yarn ends were overlapped, and the dimethyl carbonate adhering to the laminate, copper foil, and PET film was thoroughly removed. The weight was then measured using a precision balance. The weight change rate was calculated using the following formula, and the determination was made as follows.

[0142] Weight change rate (%) = |(weight after dimethyl carbonate immersion - initial weight) / initial weight| × 100

[0143] ○ (good): Weight change rate is less than 5%

[0144] × (bad): weight change rate is 5% or more

[0145] <Evaluation of Young's modulus>

[0146] The laminates, copper foils, and PET films obtained in Examples and Comparative Examples were cut into dumbbell shapes, and Young's moduli at 23° C. were measured using a tensile tester “RTC-1250A” manufactured by Orientec in accordance with JIS K7127 and evaluated using the following criteria.

[0147] ○ (good): Young's modulus is 10000 MPa or more and 40000 MPa or less

[0148] × (bad): Young's modulus is less than 10,000 MPa or exceeds 40,000 MPa

[0149] The laminated body whose Young's modulus was evaluated as "○ (good)" was able to maintain appropriate strength.

[0150] <Elongation Ratio>

[0151] The resin layer obtained from the sheets having a laminated structure of support / resin layer / protective film produced in the Examples and Comparative Examples was cut into a dumbbell shape and its elongation at break at 23°C was measured using an "RTC-1250A" tensile testing machine manufactured by Orientec in accordance with JIS K7127. The elongation at break measured above was used to calculate the elongation ratio compared to the copper foil layer using the following formula.

[0152] Elongation ratio = elongation at break of resin layer / elongation at break of copper foil layer

[0153]

Table 1

[0154]

[0155] Note) Comparative Example 1: The elongation at break of the copper foil was set to 1.0

[0156] Comparative Example 2: Elongation at break of PET film / Elongation at break of copper foil layer

[0157] In addition, in Table 1,

[0158] Regarding the resin layer thickness, since Comparative Examples 1 and 2 do not have a resin layer, they are expressed as “-”.

[0159] Regarding the total thickness of the metal foil layer, since Comparative Example 2 does not have a metal foil layer, it is expressed as “-”.

[0160] Regarding the thickness of the PET layer, since Examples 1 to 9 and Comparative Examples 1 and 3 did not have a PET layer, they were expressed as “-”.

[0161] Regarding the evaluation of film properties, Comparative Examples 1 and 2 did not have a film (resin layer) and thus were not evaluated for film properties, and thus were expressed as "-".

[0162] As can be seen from the results in Table 1, the laminates of Examples of the present invention were good in terms of film properties, weight, electrical resistance, electrolyte resistance, and Young's modulus.

[0163] Industrial applicability

[0164] The laminate of the present invention can be lightweight while maintaining appropriate strength and electrolyte resistance, and therefore can be suitably used as a current collecting layer, particularly a current collecting layer of a negative electrode of a battery.

Claims

1. A laminate comprising a resin layer formed from a resin composition containing (A) a cycloolefin polymer, and metal foil layers formed on both surfaces of the resin layer.

2. The laminate according to claim 1, wherein (A) The cycloolefin polymer comprises at least one cycloolefin copolymer.

3. The laminate according to claim 1, wherein The content of the (A) cycloolefin polymer in the resin composition is 50 to 100% by mass relative to 100% by mass of the non-volatile components of the resin composition.

4. The laminate according to claim 1, wherein The resin composition further contains (B) a styrene-based thermoplastic elastomer.

5. The laminate according to claim 4, wherein The content of the repeating unit having a reactive group in the repeating units constituting the (B) styrene-based thermoplastic elastomer is 0 to 3% by mass based on the total mass of the (B) styrene-based thermoplastic elastomer. The laminate according to claim 4 , wherein: The weight average molecular weight of the (B) styrene-based thermoplastic elastomer exceeds 50,000.

7. The laminate according to claim 4, wherein The content of the (B) styrene-based thermoplastic elastomer in the resin composition is 5 to 20% by mass relative to 100% by mass of the non-volatile components of the resin composition.

8. The laminate according to claim 1, wherein The resin composition further contains (C) a conductive filler.

9. The laminate according to claim 8, wherein The content of the (C) conductive filler in the resin composition is 0.5 to 10% by mass relative to 100% by mass of the non-volatile component of the resin composition.

10. The laminate according to claim 1, wherein The metal foil layer is a copper foil layer.

11. The laminate according to claim 1, wherein The thickness of the resin layer is 3 to 60 μm.

12. The laminate according to claim 1, wherein Young's modulus is 10000 MPa or more.

13. The laminate according to claim 1, wherein The elongation ratio is 1.2 or more.

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