Adhesive sheet

Abstract

The utility model aims to provide an adhesive sheet which can prevent discoloration caused by oxidation of a copper foil and can inhibit reduction of adhesive force between the copper foil and a resin film in a high-temperature and high-humidity environment under the condition that the resin film is adhered to the copper foil through an adhesive layer. An adhesive sheet having at least a nickel plating layer, a copper foil, and an adhesive layer in this order.

Description

Technical Field

[0001] This utility model relates to adhesive sheets. Background Technology

[0002] Due to their ease of handling, adhesive sheets are used for shielding unwanted leaked electromagnetic waves radiated by electrical or electronic equipment, shielding harmful spatial electromagnetic waves generated by other electrical or electronic equipment, and grounding for antistatic purposes. With the miniaturization and thin-film nature of electrical or electronic equipment in recent years, the adhesive sheets used in them are also required to be thinner and smaller.

[0003] It is known that conventional adhesive sheets are adhesive sheets in which the metal foil as the substrate has been chromium-plated (hereinafter, sometimes referred to as "chromate") as a rust-preventive treatment. However, such adhesive sheets have the problem that they do not provide sufficient rust prevention performance.

[0004] In addition, electronic devices are densely packed with various components. In order to insulate the entire surface or part of the metal foil, a thin insulating resin film (called an insulating film) is sometimes bonded to the entire surface or part of the metal foil through an adhesive layer.

[0005] However, in high temperature and high humidity environments, the adhesion between the insulating film and the metal foil decreases, and the insulating film is easily peeled off from the metal foil.

[0006] For example, as a plating treatment for the aforementioned metal foil, a method has been proposed to prevent copper foil from rusting, where the copper foil area is such that the concentration of copper foil per unit area is 1 to 30 mg / m². 2 The nickel plating process is performed by adjusting the amount of plating (for example, see Patent Document 1).

[0007] However, it has not been disclosed that excellent oxidation resistance (colorfastness) can be obtained by nickel plating the copper foil used as the substrate of the adhesive sheet.

[0008] Furthermore, no method is disclosed for suppressing the peeling of the insulating film from the copper foil generated under high temperature and high humidity conditions when the insulating film is adhered to the copper foil through an adhesive layer.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2000-165037 Utility Model Content

[0012] The problem to be solved by the utility model

[0013] The purpose of this invention is to provide an adhesive sheet that can prevent discoloration caused by oxidation of copper foil, and furthermore, can suppress the reduction of adhesion between copper foil and resin film in high temperature and high humidity environments when a resin film is adhered to copper foil through an adhesive layer.

[0014] Methods for solving problems

[0015] The following is a method for solving the above-mentioned problems.

[0016] <1> An adhesive sheet, characterized in that it has at least a nickel plating layer, a copper foil and an adhesive layer in sequence.

[0017] <2> According to the adhesive sheet described in <1> above, the average thickness of the nickel plating layer is 0.03 μm or more.

[0018] <3> The adhesive sheet according to <1> or <2> above has the nickel plating layer on one side of the copper foil and an adhesive layer on the other side of the copper foil.

[0019] <4> The adhesive sheet according to any one of <1> to <3> above has the nickel plating layer on both sides of the copper foil, and has the adhesive layer on at least one of the nickel plating layers.

[0020] <5> The adhesive sheet according to any one of <1> to <4> above has a resin film between the copper foil and the adhesive layer.

[0021] <6> The adhesive sheet according to any one of <1> to <5> above has at least a resin film layer, the nickel plating layer, the copper foil and the adhesive layer in sequence.

[0022] Effects of the utility model

[0023] According to the present invention, an adhesive sheet is provided that can prevent discoloration caused by oxidation of copper foil, and can also suppress the reduction of adhesion between copper foil and resin film in high temperature and high humidity environments when a resin film is adhered to copper foil through an adhesive layer. Attached Figure Description

[0024] Figure 1 A schematic cross-sectional view showing an example of the adhesive sheet of this utility model.

[0025] Figure 2 A schematic cross-sectional view showing another example of the adhesive sheet of this utility model. Detailed Implementation

[0026] (Adhesive sheet)

[0027] The adhesive sheet of this invention has at least a nickel plating layer, a copper foil and an adhesive layer in sequence, preferably a resin film layer, and other layers as needed.

[0028] The "sheet" in the adhesive sheet of this utility model includes all product forms such as single leaf, roll, thin plate, or strip.

[0029] "Adhesive sheet" is also called "adhesive tape" or "adhesive film," and will be referred to as "adhesive sheet" from now on. Additionally, the surface of the adhesive layer in the adhesive sheet is sometimes called the "adhesive surface." Furthermore, the "outermost layer" of the adhesive sheet refers to the outermost layer of the sheet after removing the release liner when the adhesive sheet has a release liner.

[0030] The adhesive sheet of this invention can be a two-sided adhesive type where both sides of the sheet are adhesive surfaces, or a one-sided adhesive type where only one side of the sheet is adhesive surface.

[0031] As an example of the aforementioned one-sided adhesive type of adhesive sheet, Figure 1 As shown, an adhesive sheet 10 can be formed by including a copper foil 1, a nickel plating layer 3 on at least one side of the copper foil 1, and an adhesive layer 2 containing an adhesive 5 on the copper foil 1 on the opposite side of the nickel plating layer 3.

[0032] Furthermore, as an example of the aforementioned one-sided adhesive type adhesive sheet, Figure 2 As shown, it is preferable to form a copper foil 1 and nickel plating layers 3 on both sides of the copper foil 1. By forming nickel plating layers 3 on both sides of the copper foil 1, warping of the copper foil 1 can be prevented.

[0033] As an example of the above-mentioned two-sided adhesive sheet, which is not illustrated, an adhesive sheet can be provided that has at least an adhesive layer, a nickel plating layer, a copper foil, a nickel plating layer and an adhesive layer formed in sequence.

[0034] <Copper Foil>

[0035] The aforementioned copper foil is used as the substrate for the aforementioned adhesive sheet.

[0036] There are no particular restrictions on the copper foil used; appropriate selection can be made according to the purpose, and commercially available products can be used.

[0037] There are no particular limitations on the average thickness of the copper foil, which can be appropriately selected according to the purpose. Preferably, it is 1 μm or more and 40 μm or less, more preferably 3 μm or more and 35 μm or less, and even more preferably 6 μm or more and 25 μm or less. If the average thickness is 1 μm or more and 40 μm or less, it can be made thinner and has excellent processability.

[0038] The average thickness of the aforementioned copper foil can be measured using a TH-102 (thickness gauge, manufactured by Tester Sangyo Co., Ltd.), measuring the thickness at 5 points at 100mm intervals along the length direction and calculating the average value.

[0039] The copper foil described above has a nickel plating layer (described later) on at least one side, and may have a nickel plating layer on the other side, or may have a plating layer of a metal other than nickel, such as chromium. Furthermore, the other side may not have a metallic plating layer.

[0040] As a plating layer for the aforementioned metal, it is typically disposed in contact with the surface of the copper foil.

[0041] <Nickel plating>

[0042] The aforementioned nickel plating layer is a layer formed on at least one side of the copper foil in the aforementioned adhesive sheet. The nickel plating layer is formed on at least one side of the copper foil by performing a plating process using a nickel plating bath containing nickel.

[0043] The nickel used in the aforementioned nickel plating layer is not particularly limited and can be appropriately selected according to the purpose. Examples include monomeric nickel, nickel-chromium, nickel-zinc, nickel-phosphorus, nickel-boron, and nickel-phosphorus-boron. Among these, monomeric nickel and nickel-zinc are preferred.

[0044] There are no particular limitations on the nickel content in the nickel plating layer, and it can be appropriately selected according to the purpose. Relative to the total amount of the nickel plating layer, it is preferably 50% by mass or more, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

[0045] There are no particular limitations on the method for determining the nickel content in the aforementioned nickel plating layer; it can be appropriately selected according to the purpose. For example, it can be determined by fluorescence X-ray determination, microscopic cross-sectional determination, etc.

[0046] The nickel content per unit area of ​​the aforementioned nickel plating layer is not particularly limited and can be appropriately selected according to the purpose, but is preferably 40 mg / m². 2 Above 50,000 mg / m 2 The following is more preferably 250 mg / m² 2 The above 45,000 mg / m 2 The following is further preferred: 1,000 mg / m² 2 The above 44,250 mg / m 2 The following is particularly preferred: 4,000 mg / m² 2 The above 44,250 mg / m² 2 The following applies if the nickel content per unit area is 250 mg / m². 2The above methods yield adhesive sheets with excellent colorfastness.

[0047] Furthermore, as the adhesive sheet of this invention, it is preferable that when an insulating film is provided on the surface, the insulating film is adhered to the nickel plating layer through an adhesive layer. This suppresses the reduction in adhesion between the copper foil with the nickel plating layer and the insulating film under high temperature and high humidity conditions, making the insulating film difficult to peel off.

[0048] The average thickness of the nickel plating layer is not particularly limited and can be appropriately selected according to the purpose. It is preferably 0.03 μm or more, more preferably 0.05 μm or more, even more preferably 0.05 μm or more and 5 μm or less, and particularly preferably 0.1 μm or more and 5 μm or less. If the average thickness is 0.03 μm or more, an adhesive sheet with excellent colorfastness is obtained.

[0049] When the nickel plating layer is formed on both sides of the copper foil 1, it is preferable that the average thickness of the nickel plating layer formed on each side is the same, from the viewpoint of preventing the copper foil from warping (curling).

[0050] Furthermore, the average thickness of the nickel plating layer when nickel plating layers are formed on both sides of the aforementioned copper foil 1 refers to the average thickness of the nickel plating layer formed on one side.

[0051] There are no particular limitations on the method for measuring the average thickness of the aforementioned nickel plating layer, and it can be appropriately selected according to the purpose. For example, the EA1400 fluorescence X-ray analyzer (manufactured by Hitachi Koshin Co., Ltd.) or the FT230 fluorescence X-ray film thickness gauge (manufactured by Hitachi Koshin Co., Ltd.) can be used for measurement.

[0052] Specifically, the average thickness was obtained by measuring the thickness at 5 points along the length direction at 100 mm intervals using a fluorescence X-ray film thickness gauge FT230.

[0053] There are no particular limitations on the resistance value of the copper foil with the above-mentioned nickel plating layer, and it can be appropriately selected according to the purpose. It is preferably 40 mΩ / cm or less, and more preferably 10 mΩ / cm or less.

[0054] There are no particular limitations on the method for measuring the resistance value of the aforementioned nickel plating layer, and it can be appropriately selected according to the purpose. For example, it can be measured by the following methods.

[0055] Specifically, in an environment of 23°C and 50%RH, the brass electrode (10mm wide x 10mm wide) is connected to a copper foil (10mm wide x 10mm wide) with a nickel plating layer, and the resistance value is measured by passing a current of 10μA through a milliohm meter (made by NF Circuit Design Module Co., Ltd.).

[0056] There are no particular limitations on the method for forming the aforementioned nickel plating layer, and it can be appropriately selected according to the purpose. Examples include electrolytic plating and non-electrolytic plating. Among these, electrolytic plating is preferred.

[0057] There are no particular limitations on the above-mentioned electroplating treatment, and it can be appropriately selected according to the purpose. For example, the entire or one side of the copper foil can be immersed in a nickel plating bath for electroplating to form a nickel plating layer.

[0058] There are no particular limitations on the nickel plating bath used in the above-mentioned electrolytic plating process, and it can be appropriately selected according to the purpose. For example, a nickel plating bath with the following composition can be used.

[0059] [Composition of the nickel plating bath]

[0060] Nickel 45g / L

[0061] Boric acid (H3BO3) 4g / L

[0062] There are no particular restrictions on the temperature for the above-mentioned electrolytic plating treatment, and it can be appropriately selected according to the purpose, preferably between 10°C and 30°C.

[0063] The pH of the nickel plating bath used in the above-mentioned electrolytic plating process is not particularly limited and can be appropriately selected according to the purpose, preferably 3.0 or higher and 5.0 or lower.

[0064] There is no particular limitation on the time for the above-mentioned electroplating treatment, and it can be appropriately selected according to the purpose, preferably between 1 second and 300 seconds.

[0065] The current density used in the above electroplating process is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0.1 A / dm. 3 Above 1.0A / dm 3 the following.

[0066] <Adhesive layer>

[0067] The adhesive layer described above serves as an adhesive surface for the adhesive sheet. This adhesive layer can exhibit insulation (non-conductive) properties, or it can exhibit conductivity by containing conductive fillers or the like. When the adhesive layer exhibits conductivity, if the adhesive surface of the adhesive layer is adhered to a conductor or other adhered object, electrical conductivity between the adhered object and the adhesive layer is ensured.

[0068] The adhesive layer described above contains an adhesive and may further contain other components such as carbon particles and conductive fillers, as needed.

[0069] <<Adhesive>>

[0070] There are no particular limitations on the adhesives used, and appropriate selection can be made according to the purpose. Examples include (meth)acrylic adhesives, urethane adhesives, polyester adhesives, synthetic rubber adhesives, natural rubber adhesives, silicone adhesives, and styrene adhesives. Among these, (meth)acrylic adhesives and styrene adhesives are preferred from the perspectives of high adhesion, low cost, and high durability.

[0071] -(meth)acrylic adhesive-

[0072] As for the aforementioned (meth)acrylic adhesive, there are no particular limitations, and it can be appropriately selected according to the purpose. It contains a (meth)acrylic polymer, preferably a tackifying resin and a crosslinking agent, and may further contain other components as needed. "(meth)acrylic acid" is used to mean acrylic acid or methacrylic acid, and "(meth)acrylate" is used to mean acrylate or methacrylate.

[0073] -(meth)acrylic acid polymer-

[0074] There are no particular limitations on the above-mentioned (meth)acrylic acid polymers, and appropriate selection can be made according to the purpose. Acrylic acid copolymers in which (meth)acrylic acid ester monomers with 1 to 14 carbon atoms are used as the main monomer components are suitable examples.

[0075] There are no particular limitations on the (meth)acrylates with 1 to 14 carbon atoms mentioned above, and appropriate selection can be made according to the purpose. Examples include meth (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. One type can be used alone, or two or more types can be used in combination. Among these, (meth)acrylates with alkyl groups having 4 to 12 carbon atoms are preferred, and (meth)acrylates having a straight-chain or branched structure with 4 to 9 carbon atoms are more preferred. From the viewpoint of obtaining adhesive sheets with high adhesive strength, n-butyl acrylate and 2-ethylhexyl acrylate are even more preferred.

[0076] The content of (meth)acrylates with 1 to 14 carbon atoms in the above-mentioned (meth)acrylate polymer is not particularly limited and can be appropriately selected according to the purpose. Preferably, it is 70% to 95% by mass or less in the monomer components constituting the (meth)acrylate polymer, and more preferably 80% to 95% by mass or less.

[0077] In addition to the monomers mentioned above, highly polar vinyl monomers can be used as monomers in the manufacture of the aforementioned acrylic polymers, as needed.

[0078] There are no particular limitations on the aforementioned highly polar vinyl monomers, and they can be appropriately selected according to the purpose. Examples include (meth)acrylic acid monomers with hydroxyl groups, (meth)acrylic acid monomers with carboxyl groups, and (meth)acrylic acid monomers with amide groups. They can be used alone or in combination of two or more.

[0079] There are no particular limitations on the vinyl monomers containing hydroxyl groups mentioned above, and they can be appropriately selected according to the purpose. Examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and other (meth)acrylate monomers.

[0080] There are no particular limitations on the aforementioned vinyl monomers containing carboxyl groups, and they can be appropriately selected according to the purpose. Examples include acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth)acrylic acid dimer, crotonic acid, ethylene oxide-modified succinic acid acrylate, and other (meth)acrylic acid monomers. Among these, acrylic acid is preferred.

[0081] There are no particular limitations on the (meth)acrylic acid monomers with amide groups mentioned above, and they can be appropriately selected according to the purpose. Examples include (meth)acrylic acid monomers such as N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N,N-dimethylacrylamide.

[0082] In addition to the above, other monomers containing sulfonic acid groups, such as vinyl acetate, ethylene oxide-modified succinic acid acrylate, and 2-acrylamide-2-methylpropanesulfonic acid, can be used as highly polar vinyl monomers.

[0083] As for the aforementioned highly polar vinyl monomer, the total amount of monomer used in the manufacture of the aforementioned acrylic polymer is preferably 1.5% by mass or more and 20% by mass or less, more preferably 1.5% by mass or more and 10% by mass or less, and 2% by mass or more and 8% by mass or less, which can form a balanced adhesive layer from the perspective of cohesive force, holding force and adhesiveness, and is therefore even more preferred.

[0084] Among the aforementioned highly polar vinyl monomers, the vinyl monomers containing hydroxyl groups are preferably used when using monomers containing isocyanate-based crosslinking agents as the adhesives described above. Specifically, there are no particular limitations on the vinyl monomers containing hydroxyl groups, and appropriate selection can be made according to the purpose; examples include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate.

[0085] As for the aforementioned vinyl monomer containing hydroxyl groups, the amount of monomers used in the manufacture of the aforementioned acrylic polymer is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.03% by mass or more and 0.3% by mass or less, relative to the total amount of monomers used in the manufacture of the aforementioned acrylic polymer.

[0086] The aforementioned acrylic polymer can be manufactured by polymerizing the monomer using known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. Among these methods, solution polymerization and bulk polymerization are preferred.

[0087] During the above polymerization, peroxide-based thermal polymerization initiators such as benzoyl peroxide and lauroyl peroxide, azo thermal polymerization initiators such as azobisisobutylnitrile, acetophenone-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, benzoin ketal-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, benzoin-based photopolymerization initiators, and benzophenone-based photopolymerization initiators can be used as needed.

[0088] There are no particular limitations on the weight-average molecular weight (Mw) of the (meth)acrylic acid polymer obtained by the above method, which can be appropriately selected according to the purpose. It is preferably 500,000 or more and 2,500,000 or less, more preferably 700,000 or more and 2,000,000 or less, and even more preferably 900,000 or more and 1,800,000 or less.

[0089] The weight-average molecular weight mentioned above is the weight-average molecular weight converted from standard polystyrene determined by gel permeation chromatography (GPC).

[0090] The molecular weight determination using the GPC method was performed using a GPC apparatus (HLC-8329GPC) manufactured by Tosoh Corporation, and the standard polystyrene conversion value was obtained under the following test conditions.

[0091] [Measurement Conditions]

[0092] • Sample concentration: 0.5% by mass (tetrahydrofuran solution)

[0093] • Sample injection volume: 100 μL

[0094] • Eluent: THF (Tetrahydrofuran)

[0095] • Flow rate: 1.0 mL / min

[0096] • Measurement temperature: 40℃

[0097] ·This column: TSKgel GMHHR-H (20) 2 pieces

[0098] • Protective pillar: TSKgel HXL-H

[0099] • Detector: Differential refractometer

[0100] • Standard polystyrene molecular weight: 10,000~20,000,000 (Tosoh Corporation)

[0101] -Tackifying resin-

[0102] As for the above-mentioned (meth)acrylic adhesive, in order to improve the adhesion to the adhered object and the surface bonding strength, it is preferable to use a substance containing a tackifying resin.

[0103] There are no particular limitations on the aforementioned tackifying resins, and they can be appropriately selected according to the purpose. Examples include rosin-based tackifying resins, polymeric rosin-based tackifying resins, polymeric rosin ester-based tackifying resins, rosin phenol-based tackifying resins, stabilized rosin ester-based tackifying resins, disproportionated rosin ester-based tackifying resins, hydrogenated rosin ester-based tackifying resins, terpene-based tackifying resins, terpene phenol-based tackifying resins, petroleum resin-based tackifying resins, and (meth)acrylate-based tackifying resins.

[0104] Among these, it is preferable to use disproportionated rosin ester tackifying resin, polymeric rosin ester tackifying resin, rosin phenol tackifying resin, hydrogenated rosin ester tackifying resin, (meth)acrylate resin, and terpene phenol resin alone or in combination of two or more.

[0105] As the aforementioned tackifying resin, a tackifying resin having a softening point of 30°C to 180°C is preferred, and a tackifying resin having a softening point of 70°C to 140°C is more preferred in forming an adhesive layer with high adhesive properties. Furthermore, when using a (meth)acrylate-based tackifying resin, a tackifying resin with a glass transition temperature of 30°C to 200°C is preferred, and a tackifying resin with a glass transition temperature of 50°C to 160°C is more preferred.

[0106] There are no particular limitations on the content of the aforementioned tackifying resin, which can be appropriately selected according to the purpose. It is preferable to have 5 to 65 parts by mass or more, or 8 to 55 parts by mass or more, relative to 100 parts by mass of the aforementioned (meth)acrylic polymer, in order to ensure good adhesion to the substrate, and therefore is more preferred.

[0107] -Crosslinking agent-

[0108] As for the above-mentioned (meth)acrylic adhesive, from the perspective of further improving the cohesive strength of the adhesive layer, it is preferable to use a (meth)acrylic adhesive containing a crosslinking agent.

[0109] There are no particular limitations on the crosslinking agents mentioned above, and they can be appropriately selected according to the purpose. Examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents. Among these, crosslinking agents that are mixed after the acrylic polymer is manufactured and then undergo a crosslinking reaction are preferred. Isocyanate-based crosslinking agents and epoxy-based crosslinking agents that are highly reactive with acrylic polymers are also preferred.

[0110] There are no particular limitations on the aforementioned isocyanate-based crosslinking agents, and they can be appropriately selected according to the purpose. Examples include toluene diisocyanate, naphthyl-1,5-diisocyanate, 1,6-hexane diisocyanate, diphenylmethane diisocyanate, phenyldimethylmethylene diisocyanate, and trimethylolpropane-modified toluene diisocyanate. Among these, trifunctional polyisocyanate compounds are preferred.

[0111] There are no particular limitations on the above-mentioned trifunctional isocyanate compounds, and they can be appropriately selected according to the purpose. Examples include toluene diisocyanate or its trimethylolpropane adduct, triphenylmethane isocyanate, etc.

[0112] As an indicator of the degree of crosslinking, the gel fraction of insoluble substances after the adhesive layer has been immersed in toluene for 24 hours is used. There are no particular limitations on the gel fraction of the adhesive layer, which can be appropriately selected according to the purpose. Preferably, it is 10% by mass or more and 70% by mass or less; more preferably, it is 25% by mass or more and 65% by mass or less; even more preferably, it is 35% by mass or more and 60% by mass or less; and particularly preferably, it is 40% by mass or more and 55% by mass or less.

[0113] Furthermore, the gel fraction mentioned above refers to the value determined by the following method. An adhesive composition was coated onto a release sheet to a thickness of 50 μm after drying. The sample was dried at 100°C for 3 minutes, and the product obtained after aging at 40°C for 2 days was cut into 50 mm squares and used as a sample. Next, the mass (G1) of the sample before toluene impregnation was determined. The toluene-insoluble fraction of the sample after impregnation in a toluene solution at 23°C for 24 hours was separated by filtering with a 300-mesh metal mesh. The mass (G2) of the residue after drying at 110°C for 1 hour was determined. The gel fraction was calculated according to the following formula. Additionally, the weight (G3) of carbon particles, conductive fillers, etc., in the sample was calculated from the mass of the sample (G1) and the composition of the adhesive.

[0114] Gel fraction (mass%) = (G2-G3) / (G1-G3) × 100

[0115] <<Carbon Particles>>

[0116] The adhesive layer described above may contain carbon particles. By containing carbon particles, the adhesive layer can achieve a degree of concealment.

[0117] There are no particular restrictions on the types of carbon particles mentioned above, and they can be appropriately selected according to the purpose. Examples include carbon black, glassy carbon, graphite, graphene, fullerene, carbon nanotubes, and carbon fibers. One type can be used alone, or two or more types can be used in combination.

[0118] There are no particular restrictions on the shape of the carbon particles mentioned above, and they can be appropriately selected according to the purpose. Examples include spherical, elliptical, columnar, cylindrical, and fibrous shapes.

[0119] There are no particular restrictions on the types of carbon black mentioned above, and they can be appropriately selected according to the purpose. Examples include furnace black, channel black, acetylene black, thermal cracking black, and lampblack.

[0120] There are no particular limitations on the graphite used, and it can be appropriately selected according to the purpose. Examples include natural graphite, float graphite, and artificial graphite. Furthermore, artificial graphite can be anisotropic graphite, isotropic graphite, or a mixture thereof; from the viewpoint of the mechanical strength of carbon particles, isotropic graphite is preferred. In addition, graphite can be crystalline, amorphous, or a mixture thereof. Furthermore, graphite can be a carbon fiber reinforced carbon composite material (C / C composite) in which graphite is reinforced with carbon fibers.

[0121] There are no particular limitations on the fullerenes mentioned above; they can be appropriately selected according to the purpose. For example, C 60 C 70 C 80 C 84 C 96 wait.

[0122] The aforementioned carbon nanotubes are cylindrical carbon polyhedra with a cylindrical closed structure formed from graphite sheets having a carbon 6-membered ring structure as the main structure. The aforementioned carbon nanotubes can be monolayer carbon nanotubes with a single layer of graphite sheet having a cylindrical closed structure; bilayer carbon nanotubes with two layers of graphite sheet having a cylindrical closed structure; and multilayer carbon nanotubes with three or more layers of graphite sheet having a concentric cylindrical closed structure.

[0123] The average particle size of the aforementioned carbon particles is not particularly limited and can be appropriately selected according to the purpose. It is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. If the average particle size of the aforementioned carbon particles is 100 nm or less, high adhesion can be obtained.

[0124] The average particle size of the aforementioned carbon particles is the average particle size based on volume. Examples of measuring devices for this purpose include, for instance, the Microtrac MT3000II manufactured by Nikkiso Corporation and the SALD-3000 laser diffraction particle size distribution analyzer manufactured by Shimadzu Corporation.

[0125] The content of the aforementioned carbon particles is not particularly limited and can be appropriately selected according to the purpose. It is preferably 75 parts by mass or less, more preferably 3 parts by mass or more than 50 parts by mass, more preferably 5 parts by mass or more than 30 parts by mass, and even more preferably 10 parts by mass or more than 20 parts by mass, relative to 100 parts by mass of the solid component of the adhesive. If the content of the aforementioned carbon particles is within the above range, high adhesive strength can be obtained.

[0126] As a method for dispersing the carbon particles in the aforementioned adhesive layer, examples include dispersing the adhesive, carbon particles, solvent, and additives using a dispersion mixer. Commercially available dispersion mixers include dissolving machines, butterfly mixers, BDM 2-shaft mixers, and planetary mixers manufactured by Inoue Manufacturing Co., Ltd. Among these, dissolving machines and butterfly mixers with a moderate share of adhesive applied during stirring are preferred.

[0127] <Other Ingredients>

[0128] Other components in the aforementioned adhesive layer are not particularly limited and can be appropriately selected according to the purpose. Examples include conductive fillers, antioxidants, ultraviolet absorbers, fillers, polymerization inhibitors, surface conditioners, antistatic agents, defoamers, viscosity modifiers, light stabilizers, weather stabilizers, heat stabilizers, antioxidants, leveling agents, organic pigments, inorganic pigments, pigment dispersants, plasticizers, softeners, flame retardants, metal passivators, silica beads, organic beads, and other additives; inorganic fillers such as silica, alumina, titanium dioxide, zirconium oxide, and antimony pentoxide, etc.

[0129] There are no particular limitations on the average thickness of the adhesive layer, which can be appropriately selected according to the purpose. It is preferably 1 μm or more and 40 μm or less, more preferably 3 μm or more and 35 μm or less, and even more preferably 6 μm or more and 25 μm or less.

[0130] The average thickness of the adhesive layer can be measured using a TH-102 (thickness gauge, manufactured by Tester Sangyo Co., Ltd.), measuring the thickness at 5 points at 100mm intervals along the length direction and calculating the average value.

[0131] <Resin film>

[0132] There are no particular limitations on the resin film layer mentioned above, and it can be appropriately selected according to the purpose. Examples include polyester film, polyethylene film, polypropylene film, polyethylene terephthalate film, and polyimide film. Among these, polyester film is preferred from the perspective of obtaining excellent insulation properties.

[0133] The aforementioned resin film layer can be synthesized appropriately or commercially available products can be used.

[0134] As for the aforementioned commercially available products, there are no particular restrictions, and appropriate selection can be made according to the purpose. Examples include 4AF53 (polyethylene terephthalate film, manufactured by Toray Industries, Inc.).

[0135] There is no particular limitation on the average thickness of the above-mentioned resin film layer, which can be appropriately selected according to the purpose. It is preferably 1 μm or more and 40 μm or less, and more preferably 3 μm or more and 35 μm or less.

[0136] The average thickness of the aforementioned resin film layer can be measured using a TH-102 (thickness gauge, manufactured by Tester Sangyo Co., Ltd.), measuring the thickness at 5 points at 100mm intervals along the length direction, and calculating the average value.

[0137] As an adhesive sheet of this invention, in addition to the above-mentioned nickel plating layer, copper foil and adhesive layer, it further has the above-mentioned resin film layer, thereby enabling it to perform insulation.

[0138] The resin film layer is preferably located between the copper foil and the adhesive layer. This improves the mechanical strength of the adhesive sheet and also suppresses electrical conductivity from the bonding surface when the adhesive surface of the adhesive sheet is bonded to the object being bonded.

[0139] As an adhesive sheet of this invention, when the resin film layer is present between the copper foil and the adhesive layer, for example, a structure can be provided in which at least a nickel plating layer, a copper foil, a resin film layer, and an adhesive layer (hereinafter sometimes referred to as "adhesive layer C1") are sequentially formed. Here, the "adhesive layer C1" is the adhesive layer located on the outermost layer of the adhesive sheet.

[0140] Furthermore, as the aforementioned adhesive sheet, examples include structures that sequentially comprise at least a nickel plating layer, a copper foil, an adhesive layer (hereinafter sometimes referred to as "adhesive layer C2"), a resin film layer, and an adhesive layer C1. Here, the aforementioned "adhesive layer C2" refers to an adhesive layer located between the layers of the adhesive sheet.

[0141] As the resin film layer described above, in the above structure, it is usually adjacent to the copper foil (or the plating layer if it has a plating) through the adhesive layer C2, and is located between the copper foil and the adhesive layer C1.

[0142] As the aforementioned resin film layer, when the adhesive sheet of this invention is a two-sided adhesive type adhesive sheet, it can be disposed between the copper foil and the outermost adhesive layer C1 disposed on both sides of the copper foil. In this case, it is preferable that the nickel plating layer is adjacent to the copper foil, and the resin film layer is adjacent to the adhesive layer C1.

[0143] As the aforementioned adhesive sheet, when a resin film layer is present between the copper foil and the adhesive layer C1, it is difficult to peel off between the resin film layer and the copper foil. Therefore, it is preferable to have a nickel plating layer on both sides of the copper foil. That is, as the aforementioned adhesive sheet, it is preferable to have at least a nickel plating layer (hereinafter, sometimes referred to as "nickel plating layer A1"), a copper foil, a nickel plating layer (hereinafter, sometimes referred to as "nickel plating layer A2"), a resin film layer, and an adhesive layer C1 in sequence. Furthermore, it is preferable to have an adhesive layer C2 between the nickel plating layer A2 and the resin film layer. In this case, it is preferable that the nickel plating layer A1 and the nickel plating layer A2 are adjacent to the copper foil, and the resin film layer is adjacent to the adhesive layer C1.

[0144] Furthermore, as an adhesive sheet of this invention, examples include structures that sequentially comprise at least the aforementioned resin film layer, the aforementioned nickel plating layer, the aforementioned copper foil, and the aforementioned adhesive layer C1. In this case, by having the aforementioned resin film, which functions as an insulating film, on the surface where the aforementioned nickel plating layer is located within the aforementioned copper foil, the adhesive sheet can exhibit surface insulation. In this case, it is preferable that the aforementioned resin film layer is arranged adjacent to the aforementioned adhesive layer C2 and the nickel plating layer.

[0145] The resin film layer described above can be partially disposed on the nickel plating layer, or it can be disposed over the entire area of ​​the nickel plating layer. Among these, partial disposal is preferred.

[0146] As the aforementioned resin film layer, which forms the outermost layer of one of the adhesive sheets, the aforementioned adhesive layer C1 can also form the outermost layer of the other adhesive surface of the adhesive sheet. In this case, the aforementioned nickel plating layer is adjacent to the aforementioned copper foil. Furthermore, the aforementioned copper foil and the aforementioned adhesive layer C1 can be adjacent, possibly through the aforementioned nickel plating layer or other metal plating layers.

[0147] Furthermore, as an adhesive sheet of this utility model, for example, a structure may be provided that has at least the above-mentioned resin film layer (hereinafter, sometimes referred to as "resin film layer D1"), the above-mentioned nickel plating layer, the above-mentioned copper foil, the above-mentioned resin film layer (hereinafter, sometimes referred to as "resin film layer D2") and the above-mentioned adhesive layer C1 in sequence.

[0148] An adhesive layer C2 is typically disposed between the resin film layer D1 and the nickel plating layer, and between the copper foil and the resin film layer D2. The copper foil and the resin film layer D2 may have a nickel plating layer or other metal plating layer, preferably a nickel plating layer.

[0149] There are no particular limitations on the adhesive layer C2 used to bond the resin film layer to the copper foil or metal plating layer. It can be appropriately selected according to the purpose. For example, the same layer as the adhesive layer (adhesive layer C1) can be used.

[0150] There are no particular limitations on the manufacturing method of the adhesive sheet of this invention, and it can be appropriately selected according to the purpose. For example, the composition containing the adhesive can be coated on the copper foil using a roller coater, a die coater, or the like, and then dried to manufacture it. Alternatively, it can be manufactured by a transfer method that adheres the adhesive layer formed on the release liner to the copper foil.

[0151] When manufacturing the above-mentioned adhesive sheet as a double-sided adhesive sheet, a composition containing the above-mentioned adhesive can be applied to the surface of the release liner using a roller coater or the like, dried to form an adhesive layer, and then manufactured by a transfer method that attaches the adhesive layer to both sides of the copper foil.

[0152] When bonding the adhesive layer formed on the release liner to the copper foil, hot lamination is preferred from the viewpoint of imparting excellent adhesion between the copper foil and the adhesive layer.

[0153] The preferred temperature for the above-mentioned heat lamination is 60°C or higher and 150°C or lower, more preferably 70°C or higher and 130°C or lower, and even more preferably 80°C or higher and 110°C or lower, considering the suppression of adhesion and shrinkage of the substrate.

[0154] -Remove Liner-

[0155] There are no particular limitations on the release liner used, and it can be appropriately selected according to the purpose. Examples include paper such as kraft paper, cellophane, and woodfree paper; resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate; laminated paper on which the above-mentioned paper and resin film are stacked; one or both sides of the product on which the above-mentioned paper has been filled with clay, polyvinyl alcohol, etc.; and release liner treated with silicone resin, etc.

[0156] The average total thickness of the adhesive sheet is not particularly limited and can be appropriately selected according to the purpose. Preferably, it is 100 μm or less, more preferably 65 μm or less, and even more preferably 50 μm or less. If the total thickness is 100 μm or less, adhesion can be ensured while achieving a thinner adhesive sheet, contributing to the miniaturization of portable electronic devices. Furthermore, the average total thickness of the adhesive sheet refers to the thickness of the adhesive sheet itself excluding the release liner.

[0157] The adhesive sheet of this invention is applied to stainless steel plates (SUS plates) at a temperature of 23°C and a humidity of 50%RH. The application is performed by pressing the adhesive sheet with a 2kg roller in one reciprocating pressing motion. After standing for 1 hour, the 180-degree peel adhesion force at 300mm / min is preferably above 8N / 25mm.

[0158] If it is within the above range, it is easy to suppress peeling. In addition, in defective products bonded during the manufacturing process, peeling of the adhesive sheet becomes possible.

[0159] <Uses>

[0160] The adhesive sheet of this invention can prevent discoloration caused by oxidation of copper foil. Therefore, it is useful for shielding electromagnetic waves used in electrical or electronic equipment, shielding harmful spatial electromagnetic waves generated by other electrical or electronic equipment, and antistatic grounding fixation. Among these, it is suitable for use in portable electronic devices where the trend towards thinness is underway and the internal volume of the casing is strictly limited, and is particularly suitable for use as an adhesive to built-in components of small electronic terminals.

[0161] Example

[0162] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments in any way.

[0163] (Copper foil plating treatment)

[0164] -Example of manufacturing copper foil A-

[0165] A copper foil (average thickness 10 μm, untreated, surface roughness Rz = 0.38 μm on the glossy side and Rz = 1.40 μm on the matte side) was immersed in a nickel plating bath with the following composition at 20 °C, pH 3.5, and a current density of 0.2 A / dm³. 3 Electroplating was performed under specific conditions to obtain a copper foil with a nickel plating layer (average thickness 0.5 μm, 4.425 g / m²) on both sides (one side being glossy and the other being matte) of the aforementioned copper foil. 2 Copper foil A (average thickness 11μm).

[0166] [Composition of the nickel plating bath]

[0167] Nickel 45g / L

[0168] Boric acid (H3BO3) 4g / L

[0169] The resistance of the obtained copper foil A was measured to be 4 mΩ. The surface roughness Rz of the nickel plating layer on the glossy side of copper foil A was 0.44 μm, and the surface roughness Rz of the nickel plating layer on the matte side was 1.40 μm.

[0170] In addition, the average thickness of copper foil A and the plating layer, the resistance value of copper foil A, and the surface roughness of the nickel plating layer on the glossy side and the nickel plating layer on the matte side of copper foil A are values ​​obtained by the following methods.

[0171] <Determination of the average thickness of copper foil A and the coating>

[0172] The average thickness of the copper foil was obtained by measuring the thickness at 5 points at 100mm intervals along the length direction using a TH-102 (thickness gauge, manufactured by Tester Industrial Co., Ltd.).

[0173] The average thickness of the coating was obtained by measuring the thickness at 5 points at 100 mm intervals along the length direction using a fluorescent X-ray film thickness gauge FT230.

[0174] <Determination of the resistance value of copper foil A>

[0175] A brass electrode (10mm wide x 10mm wide) is attached to one side of copper foil A (10mm wide x 10mm wide). Under conditions of 23°C and 50% RH, with a surface pressure of 20N applied from the attachment point of the brass electrode, the brass electrode is connected to copper foil A. The resistance value is measured using a milliohm meter (NF Circuit Design Module Co., Ltd.) with a current of 10μA flowing through it.

[0176] <Method for determining the surface roughness of the glossy and matte surfaces in copper foil A>

[0177] The surface roughness of the glossy and matte surfaces of copper foil A was determined according to JIS B0601-2013.

[0178] -Example of manufacturing copper foil B-

[0179] In the manufacturing example of copper foil A, a plating process was performed to make the average thickness of the nickel plating layer 0.05 μm. Otherwise, the plating process was performed in the same manner as in the manufacturing example of copper foil A, resulting in a copper foil with a nickel plating layer (average thickness 0.05 μm, 0.4425 g / m²) formed on both sides (one side being a glossy surface and the other a matte surface). 2 Copper foil B (average thickness 10μm).

[0180] The resistance value of copper foil B was measured in the same manner as that of copper foil A, and the result was 4 mΩ. The surface roughness Rz of the nickel plating layer on the glossy side of copper foil A was 0.41 μm, and the surface roughness Rz of the nickel plating layer on the matte side was 1.40 μm.

[0181] -Example of copper foil C manufacturing-

[0182] A single side of a copper foil (average thickness 10 μm, untreated) was immersed in the aforementioned nickel plating bath at 20°C, pH 3.5, and a current density of 0.2 A / dm³. 3 Electroplating was performed under specific conditions to form a nickel plating layer (average thickness 0.05 μm, 0.4425 g / m²) on one side (matte side) of the copper foil. 2Then, the other side of the copper foil is immersed in a chromium plating bath with the following composition, at 30°C, pH 2.3, and a current density of 5 A / dm³. 3 Electroplating was performed under the specified conditions to obtain a chromium plating layer (average thickness 0.005 μm, 0.036 g / m²) formed on one side (glossy side) of the copper foil. 2 The copper foil C (average thickness 10μm) is used.

[0183] [Composition of the chromium plating bath]

[0184] Chromium: 5g / L

[0185] The resistance value of the obtained copper foil C was measured in the same manner as that of copper foil A, and the result was 4 mΩ. The surface roughness Rz of the chromium plating layer on the glossy side of copper foil C was 0.41 μm, and the surface roughness Rz of the nickel plating layer on the matte side was 1.40 μm.

[0186] -Example of copper foil D manufacturing-

[0187] A single side of a copper foil (average thickness 10 μm, untreated) was immersed in the aforementioned nickel plating bath at 20°C, pH 3.5, and a current density of 0.2 A / dm³. 3 Electroplating was performed under specific conditions to form a nickel plating layer (average thickness 0.03 μm, 0.2655 g / m²) on one side (matte side) of the copper foil. 2 Then, the other side of the copper foil is immersed in the chromium plating bath at 30°C, pH 2.3, and a current density of 5 A / dm³. 3 Electrolytic plating was performed under the specified conditions to obtain a chromium plating layer (average thickness 0.005 μm, 0.036 g / m²) on one side (glossy side) of the copper foil. 2 The copper foil D (average thickness 10μm) is used.

[0188] The resistance value of the obtained copper foil D was measured in the same manner as that of copper foil A, and the result was 4 mΩ. The surface roughness Rz of the chromium plating layer on the glossy side of copper foil D was 0.41 μm, and the surface roughness Rz of the nickel plating layer on the matte side was 1.40 μm.

[0189] -Example of copper foil E manufacturing-

[0190] The copper foil (average thickness 10 μm, untreated) was immersed entirely in the above-mentioned chromium plating bath at 30°C, pH 2.3, and a current density of 5 A / dm³. 3 Electrolytic plating was performed under specific conditions to obtain copper foil with chromium plating layers (average thickness 0.005 μm, 0.036 g / m²) on both sides (one side being glossy and the other being matte) of the aforementioned copper foil. 2 The copper foil E (average thickness 10μm) is used.

[0191] The resistance value of the obtained copper foil E was measured in the same manner as that of copper foil A, and the result was 4 mΩ. The surface roughness Rz of the chromium plating layer on the glossy side of copper foil E was 0.41 μm, and the surface roughness Rz of the chromium plating layer on the matte side was 1.40 μm.

[0192] -Example of copper foil F manufacturing-

[0193] A copper foil (average thickness 10 μm, untreated) was immersed entirely in a benzotriazole treatment bath with the following composition and subjected to rust prevention treatment at 25°C and pH 0.7. After drying, a benzotriazole layer (average thickness 0.1 μm, 0.137 g / m²) was formed on both sides of the copper foil (one side being glossy and the other being matte). 2 The copper foil F (average thickness 10μm) is used.

[0194] [Composition of the benzotriazole treatment bath]

[0195] • Hydrochloric acid: 0.2M / L

[0196] • Ammonium chloride: 1.0 M / L

[0197] Benzotriazole: 0.2M / L

[0198] The resistance value of the obtained copper foil F was measured in the same manner as that of copper foil A, and the result was 4 mΩ. The surface roughness Rz of the benzotriazole layer on the glossy side of copper foil F was 0.41 μm, and the surface roughness Rz of the benzotriazole layer on the matte side was 1.40 μm.

[0199] (Example 1: Synthesis of Acrylic Acid Copolymer)

[0200] <Ethyl acetate solution of acrylic acid copolymer>

[0201] In a reaction vessel equipped with a stirrer, cooler, thermometer, and dropping funnel, 75.0 parts by weight of n-butyl acrylate, 19.0 parts by weight of 2-ethylhexyl acrylate, 3.9 parts by weight of vinyl acetate, 2.0 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, and 0.1 parts by weight of 2,2'-azobisisobutyl nitrile (as polymerization initiator) were dissolved in 100 parts by weight of ethyl acetate. After nitrogen purging, polymerization was carried out at 80°C for 12 hours to obtain an acrylic copolymer with a weight-average molecular weight of 600,000 (1). The weight-average molecular weight of the above acrylic copolymer was determined using the following method.

[0202] <Weight-average molecular weight of acrylic copolymers>

[0203] The molecular weight of the acrylic copolymer was determined using the GPC method using a GPC apparatus (HLC-8329GPC) manufactured by Tosoh Corporation, under the following test conditions, to obtain the standard polystyrene conversion value.

[0204] [Measurement Conditions]

[0205] • Sample concentration: 0.5% by mass (tetrahydrofuran solution)

[0206] • Sample injection volume: 100 μL

[0207] • Eluent: THF (Tetrahydrofuran)

[0208] • Flow rate: 1.0 mL / min

[0209] • Measurement temperature: 40℃

[0210] ·This column: TSKgel GMHHR-H (20) 2 pieces

[0211] • Protective pillar: TSKgel HXL-H

[0212] • Detector: Differential refractometer

[0213] • Standard polystyrene molecular weight: 10,000~20,000,000 (manufactured by Tosoh Corporation) (Synthesis Example 2 of acrylic copolymer)

[0214] <Ethyl acetate solution of acrylic acid copolymer>

[0215] In a reaction vessel equipped with a stirrer, cooler, thermometer, and dropping funnel, 97.98 parts by mass of n-butyl acrylate, 2.0 parts by mass of acrylic acid, 0.02 parts by mass of 2-hydroxyethyl acrylate, and 0.2 parts by mass of 2,2'-azobisisobutyl nitrile (as polymerization initiator) were dissolved in 100 parts by mass of ethyl acetate. After nitrogen purging, polymerization was carried out at 80°C for 8 hours to obtain an acrylic copolymer (2) with a weight-average molecular weight of 900,000. The weight-average molecular weight of the acrylic copolymer was determined using the same method as that used for acrylic copolymer (1).

[0216] (Example 1 of the preparation of adhesive composition)

[0217] -Adhesive formulation-

[0218] Relative to 100 parts by weight (solid component) of the above acrylic copolymer (1), 10 parts by weight of polymeric pentaerythritol rosin (PENSEL D-135, manufactured by Arakawa Chemical Industry Co., Ltd., softening point 135°C) and 10 parts by weight of disproportionated rosin glycerol ester (SUPER ESTER A-100, manufactured by Arakawa Chemical Industry Co., Ltd.) were mixed, stirred, and then ethyl acetate was added to obtain an adhesive with a solid component of 40% by weight of acrylic polymer.

[0219] -Preparation of adhesive composition-

[0220] To prepare adhesive composition A, 10 parts by weight of black colorant (DICTON Black AR8555, manufactured by DIC Corporation, carbon black content: 45% by weight, resin solid content: 49% by weight) and 1.2 parts by weight of BURNOCK NC-40 (manufactured by DIC Corporation, solid content 40% by weight) as crosslinking agent were mixed in a dispersing mixer for 10 minutes.

[0221] (Example 2 of adhesive composition preparation)

[0222] -Adhesive formulation-

[0223] Compared with 100 parts by weight of the above acrylic copolymer (2) (solid component), 5 parts by weight of mixed polymerized rosin pentaerythritol ester (PENSEL D-135, manufactured by Arakawa Chemical Industry Co., Ltd., softening point 135°C), 20 parts by weight of disproportionated rosin glycerol ester (KE-100, manufactured by Arakawa Chemical Industry Co., Ltd.) and 25 parts by weight of petroleum resin (FTR6100) were stirred, and then ethyl acetate was added to obtain an adhesive with a solid component of 40% by weight of acrylic polymer.

[0224] -Preparation of adhesive composition-

[0225] Adhesive composition B is prepared by mixing 2 parts by mass of BURNOCK NC-40 (manufactured by DIC Corporation, 40% by mass of solids) as a crosslinking agent and 70 parts by mass of ethyl acetate in a dispersing mixer for 10 minutes, relative to 100 parts by mass of the adhesive (solid component).

[0226] (Example 3 of adhesive composition preparation)

[0227] - Adhesive preparation -

[0228] The composition a (a mixture of styrene-isoprene diblock copolymer and styrene-isoprene triblock copolymer, wherein 24% by mass of the styrene-derived structural unit as shown in the following chemical formula (1), and the proportion of styrene-isoprene diblock copolymer is 67% by mass relative to the total amount of the above composition a) consists of 100 parts by mass of QUINTONG115 (C5 / C9 petroleum resin, manufactured by Zeon Corporation of Japan, softening point 115°C), 40 parts by mass of polymeric rosin resin (Pensel D-160, manufactured by Arakawa Chemical Industry Co., Ltd., softening point 150°C~165°C), and 30 parts by mass of polybutene (Nichishi Polybutene). HV-50 (manufactured by JX Nippon Minerals Energy Co., Ltd., pour point -12.5°C) 5 parts by weight and antioxidant (tetra-[methylene-3-(3'5'-di-tert-butyl-4-hydroxyphenyl)propionate]methane) 1 part by weight are mixed and dissolved in toluene as a medium, and stirred to obtain a styrene-based adhesive (adhesive composition C) with a solid content of 40% by weight.

[0229] [Chemistry 1]

[0230]

[0231] (Example 1)

[0232] <Making of Adhesive Sheets>

[0233] The obtained adhesive composition 1 was coated onto a release film (PET38×1, A3, manufactured by Nippa Corporation) using a comma coater to achieve an average thickness of 10 μm after drying. The coating was then dried in a desiccator at 80°C for 2 minutes to obtain an adhesive layer. This adhesive layer was then bonded to the glossy surface of the copper foil A. A laminator was used to apply pressure at 40°C with a linear pressure of 100 N / cm, and the laminator was cured at 40°C for 48 hours to produce the adhesive sheet of Example 1.

[0234] The average thickness of the obtained adhesive sheet, adhesive layer, and coating is determined as follows.

[0235] <Determination of the average thickness of the adhesive sheet>

[0236] The average thickness of each adhesive sheet is the average value obtained by measuring the thickness of the sheet (excluding the release film) with the release film removed using a TH-102 (thickness gauge, manufactured by Tester Sangyo Co., Ltd.) at 5 points at 100mm intervals along the length direction.

[0237] <Determination of the average thickness of the adhesive layer>

[0238] A portion of the adhesive layer formed on the surface of the release film used in the fabrication of the aforementioned adhesive sheet was extracted to create a sample in which one side was lined with S25 (manufactured by UNITIKA Co., Ltd., polyethylene terephthalate film, average thickness 25 μm). The release film was peeled off from the sample, and its average thickness was measured using a TH-102 (thickness gauge, manufactured by Tester Sangyo Co., Ltd.). The value subtracted from the thickness of S25 was taken as the thickness of the adhesive layer.

[0239] (Example 2)

[0240] In Example 1, copper foil A was replaced with copper foil B. Otherwise, the same procedure was followed as in Example 1 to produce the adhesive sheet of Example 2.

[0241] (Example 3)

[0242] In Example 1, copper foil A was replaced with copper foil C. Otherwise, the same procedure was followed as in Example 1 to produce the adhesive sheet of Example 3.

[0243] (Example 4)

[0244] In Example 1, copper foil A was replaced with copper foil D. Otherwise, the same procedure was followed as in Example 1 to produce the adhesive sheet of Example 4.

[0245] (Example 5)

[0246] The obtained adhesive composition B was coated onto a polyethylene terephthalate film (4AF53, average thickness: 3.5 μm, manufactured by Toray Industries, Inc.) using a die coater to achieve an average thickness of 2 μm after drying. After drying in an 80°C desiccator for 2 minutes to obtain adhesive layer C2, it was bonded to the glossy surface of the copper foil A and cured at 40°C for 48 hours to produce a copper foil with a polyester film.

[0247] Then, the obtained adhesive composition B was coated on a release film (PET38×1, A3, manufactured by Nippa Corporation) with an average thickness of 10 μm after drying using a comma coater. After drying in an 80°C dryer for 2 minutes to obtain adhesive layer C1, it was laminated to the polyester film surface of the copper foil with the above-mentioned polyester film. Then, it was pressed at 40°C with a linear pressure of 100 N / cm using a laminator and cured at 40°C for 48 hours to produce the adhesive sheet of Example 5.

[0248] (Example 6)

[0249] In Example 1, adhesive composition A was replaced with adhesive composition C. Otherwise, the same procedure as in Example 1 was followed to produce the adhesive sheet of Example 6.

[0250] (Comparative Example 1)

[0251] In Example 1, copper foil A was replaced with copper foil E. Otherwise, the same procedure as in Example 1 was followed to produce the adhesive sheet of Comparative Example 1.

[0252] (Comparative Example 2)

[0253] In Example 1, copper foil A was replaced with copper foil F. Otherwise, the same procedure as in Example 1 was followed to produce the adhesive sheet of Comparative Example 2.

[0254] Next, the adhesive sheets of Examples 1-6 and Comparative Examples 1-2 were evaluated as follows. The results are shown in Tables 1 and 2. "Average thickness (μm)※" in the tables indicates the average thickness of the copper foil with the plating or benzotriazole layer formed (the thickness of the plating, etc.).

[0255] <Methods for evaluating adhesive strength>

[0256] The adhesive sheets obtained from the examples and comparative examples were cut to a width of 25 mm.

[0257] Next, under the conditions of ambient temperature 23℃ and humidity 50%RH, the above adhesive sheet was pasted onto a stainless steel plate (SUS plate, stainless steel plate with hairline polishing treatment using 360 grit water-resistant abrasive paper), and a 2kg roller was used to press them together in one reciprocating motion. Then, the product was placed at room temperature for 1 hour as a test piece.

[0258] The test pieces were subjected to a Tancellation universal tensile testing machine (manufactured by A&D Corporation, Tancellation RTA-100) under the same temperature and humidity conditions as described above, and were peeled at a speed of 300 mm / min, with a 180-degree peel, to determine the adhesive strength. Adhesive strength of 8 N / 25 mm or higher was considered excellent.

[0259] <Evaluation Methods for Colorfastness>

[0260] After placing each adhesive sheet in an environment of 85°C and 85% RH for 500 hours, visually observe the discoloration of the surface opposite to the adhesive layer of each adhesive sheet (the surface on the coating side). Evaluate the discoloration resistance based on the following evaluation criteria.

[0261] The adhesive sheet of Example 1 did not change color even after being placed in an environment of 85°C and 85%RH for 500 hours.

[0262] After being placed at 85°C and 85% RH for 500 hours, some of the adhesive sheets in Example 2 showed slight discoloration.

[0263] After being placed at 85°C and 85% RH for 500 hours, some of the adhesive sheets in Comparative Examples 1 and 2 showed significant discoloration.

[0264] [Evaluation Criteria]

[0265] ◎: No color change

[0266] ○: Some parts have changed color

[0267] ×: The whole body exhibits significant discoloration.

[0268] <Evaluation Methods for the Adhesion Reliability of Insulating Films>

[0269] The adhesive sheets obtained from the examples and comparative examples were cut to a width of 25 mm, and the adhesive layer side of the adhesive sheets was adhered to an SUS board. Next, an insulating film with a 2 mm wide adhesive layer (a sheet adhesive sheet with a polyester substrate (hereinafter, sometimes referred to as "insulating adhesive sheet"), manufactured by DIC Corporation, PF-025H, with an average thickness of 60 μm) was adhered to the copper foil side of the adhesive sheet on the SUS board, and pressed against it once by rolling a 2 kg roller to obtain a test sheet.

[0270] Then, the test pieces were placed at 85°C and 85% RH for 168 hours, followed by 23°C and 50% RH for 1 hour. Then, at 23°C and 50% RH, the insulating adhesive of the test pieces was peeled using a Tanselten universal tensile testing machine (manufactured by A&D Corporation, Tanselten RTA-100) at a speed of 300 mm / min to determine the 180-degree peel bond strength.

[0271] The adhesion strength of 1.0 N / 2 mm or higher was evaluated as excellent bonding reliability between the adhesive sheet and the polyester substrate. Furthermore, after being placed in an environment of 23°C and 50% RH for 1 hour without exposure to 85°C, the adhesion strength when peeling off the insulating adhesive sheet (PF-025H) from the test sheet was 1.4 N / 2 mm in Examples 1-6 and Comparative Examples 1-2.

[0272] <Insulation Evaluation Methods>

[0273] For each adhesive sheet, 10 samples were tested using a testing machine. The number of samples that were punctured from the side where the adhesive layer was formed with a pressure of 1.5N and made conductive was counted. Based on the number of conductive samples, the insulation was evaluated according to the following evaluation criteria. In addition, conductive samples also include those that were barely conductive.

[0274] [Evaluation Criteria]

[0275] ◎: 0 samples are conductive.

[0276] ○: The number of conductive samples is more than one and less than two.

[0277] ×: More than 3 samples are conductive.

[0278] [Table 1]

[0279]

[0280] [Table 2]

[0281]

[0282] Explanation of symbols

[0283] 1. Copper foil

[0284] 2 adhesive layer

[0285] 3 Nickel plating layer

[0286] 5. Adhesive

[0287] 10 Adhesive Sheets

Claims

1. An adhesive sheet, characterized in that, It has at least a nickel plating layer, a copper foil, and an adhesive layer in sequence, wherein the average thickness of the nickel plating layer is more than 0.1 μm and less than 5 μm.

2. The adhesive sheet according to claim 1, characterized in that, It has the nickel plating layer on one side of the copper foil and the adhesive layer on the other side of the copper foil.

3. The adhesive sheet according to claim 1, characterized in that, It has the nickel plating layer on both sides of the copper foil, and the adhesive layer is on at least one of the nickel plating layers.

4. The adhesive sheet according to claim 1, characterized in that, A resin film is present between the copper foil and the adhesive layer.

5. The adhesive sheet according to claim 1, characterized in that, It has at least, in sequence, a resin film layer, the nickel plating layer, the copper foil, and the adhesive layer.

Images