Aqueous metal surface treatment agent and method for producing metal foil laminate

Abstract

The present disclosure provides an aqueous surface treatment agent which is capable of improving adhesion and electrolyte solution resistance when laminating a metal. An aqueous metal surface treatment agent according to one embodiment of the present invention is used for surface treatment of a metal and includes a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C). The water-soluble or water-dispersible acrylic resin (B) has a weight average molecular weight of 50,000 to 1,000,000 inclusive, and a solid acid value of more than 740 mgKOH / g.

Description

Aqueous metal surface treatment agent and method for producing metal foil laminate

[0001] The present invention relates to an aqueous metal surface treatment agent and a method for producing a metal foil laminate.

[0002] Conventionally, in order to protect metal and to provide a design, metal is laminated by adhering a laminate film to the metal.

[0003] In order to maintain the aesthetic appearance and corrosion resistance of the laminated metal, it is important to improve the adhesion of the laminate film. For example, a method of forming a chemical conversion coating layer on one or both sides of an aluminum foil is known.

[0004] Known methods for forming a chemical conversion coating layer on an aluminum surface include, for example, a method using a surface treatment agent containing a water-soluble trivalent chromium compound and a water-soluble organic polymer compound (see, for example, Patent Document 1).

[0005] Japanese Unexamined Patent Publication No. 53-037550

[0006] When a laminated metal is used as an exterior material for a battery, it is desirable to improve adhesion and electrolyte resistance.

[0007] An object of the present invention is to provide an aqueous surface treatment agent that can improve adhesion and electrolyte resistance when laminating metals.

[0008] (1) The present disclosure relates to an aqueous metal surface treatment agent used for metal surface treatment, the aqueous metal surface treatment agent comprising a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), wherein the water-soluble or water-dispersible acrylic resin (B) has a weight-average molecular weight of 50,000 or more and 1,000,000 or less and an acid value of the solid content of more than 740 mgKOH / g.

[0009] (2) The aqueous metal surface treatment agent according to (1), wherein the ratio of the mass of trivalent chromium contained in the trivalent chromium compound (A) to the total solid content of the aqueous metal surface treatment agent is 5% or more and 15% or less, calculated as trivalent chromium, and the ratio of the mass of the solid content of the phosphate compound (C) to the total solid content of the aqueous metal surface treatment agent is 5% or more and 40% or less, calculated as phosphate ions.

[0010] (3) The aqueous metal surface treatment agent according to (1) or (2), further comprising nitrate ions (D), and the molar ratio (A / D) of the trivalent chromium compound (A) to the nitrate ions (D) is 0.3 or more and 0.4 or less.

[0011] (4) The present disclosure also relates to a method for producing a metal foil laminate, the method including: a surface treatment step of treating at least one surface of a metal foil; and a lamination step of laminating a film on the surface of the metal foil treated in the surface treatment step, wherein the aqueous metal surface treatment agent used in the surface treatment step includes a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), and the water-soluble or water-dispersible acrylic resin (B) has a weight-average molecular weight of 50,000 or more and 1,000,000 or less and an acid value of the solid content of more than 740 mgKOH / g.

[0012] (5) The method for producing a metal foil laminate according to (4), wherein the mass ratio of trivalent chromium contained in the trivalent chromium compound (A) to the total solid content of the aqueous metal surface treatment agent is 5% to 15% in terms of trivalent chromium, and the mass ratio of the solid content of the phosphate compound (C) to the total solid content of the aqueous metal surface treatment agent is 5% to 40% in terms of phosphate ions.

[0013] (6) The method for producing a metal foil laminate according to (4) or (5), wherein the aqueous metal surface treatment agent further contains nitrate ions (D), and the molar ratio (A / D) of the trivalent chromium compound (A) to the nitrate ions (D) is 0.3 or more and 0.4 or less.

[0014] According to the present invention, it is possible to provide an aqueous surface treatment agent that can improve adhesion and electrolyte resistance when laminating metals.

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the description of the following embodiments.

[0016] [Aqueous Surface Treatment Agent] The aqueous surface treatment agent of the present embodiment is used for treating the surface of a metal.

[0017] The metal to be surface-treated is not particularly limited, but examples include iron, zinc, aluminum, copper, nickel, etc., and two or more types may be used in combination. That is, the metal may be an alloy. Examples of alloy components may include carbon, nitrogen, oxygen, phosphorus, sulfur, silicon, manganese, chromium, titanium, molybdenum, etc. Among these, from the viewpoints of processability and adhesion, aluminum or aluminum alloys, iron or iron alloys, or copper or copper alloys are preferred, and aluminum or aluminum alloys are more preferred. Examples of aluminum alloys include Al—Cu alloys, Al—Mn alloys, Al—Si alloys, Al—Mg alloys, Al—Mg—Si alloys, Al—Zn—Mg alloys, and aluminum die-casts (ADC materials). When the surface-treated metal of this embodiment described below is used as a battery exterior material, it is preferable to use 8079 material or the like as the aluminum alloy. Examples of aluminum alloys that can be used for other applications include 3004, 3104, and 3005 materials for beverage and food can bodies, 5052 and 5182 materials for beverage and food can lids, 1050, 1100, and 1200 materials for dry battery containers, and 8021 materials for electrodes. Examples of iron alloys include cold-rolled steel sheets such as SPCC, SPCD, and SPCE, and stainless steel (SUS). Examples of SUS include austenitic stainless steels such as SUS304, SUS301, and SUS316, ferritic stainless steels such as SUS430, and martensitic stainless steels such as SUS410. Examples of zinc alloys include Zn-Al alloys. Examples of copper alloys include brass. Examples of nickel alloys include Ni-P alloys.

[0018] The metal, which may be an alloy, may be plated. Examples of the metal to be plated include nickel, zinc, chromium, iron, tin, copper, silver, platinum, and gold, and two or more metals may be used in combination. Examples of plating methods include electroplating, electroless plating, hot-dip plating, vacuum deposition, sputtering, and ion plating. Examples of plated metals include Ni-plated steel, Ni-plated copper, Zn-plated steel, and Zn-Ni-plated steel. Examples of the metal to be plated (base material) include cold-rolled steel sheets such as SPCC, SPCD, and SPCE, and copper sheets.

[0019] The aqueous metal surface treatment agent according to this embodiment contains a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C). Preferably, the aqueous metal surface treatment agent further contains nitrate ions (D).

[0020] The aqueous surface treatment agent of this embodiment may contain hexavalent chromium. In this case, the content of hexavalent chromium in the aqueous surface treatment agent of this embodiment is, for example, less than 0.04 mass%, less than 0.02 mass%, less than 0.01 mass%, less than 0.001 mass%, less than 0.0001 mass%, less than 0.00001 mass%, or less than 0.000001 mass%. The content of hexavalent chromium in the aqueous surface treatment agent of this embodiment is preferably minimized, i.e., a trace amount, and most preferably 0 mass%. The coating formed by surface treating a metal with the aqueous surface treatment agent of this embodiment preferably contains substantially no hexavalent chromium, and most preferably contains no hexavalent chromium.

[0021] (Trivalent chromium compound (A)) The trivalent chromium compound (A) is contained in the aqueous surface treatment agent, and improves the resistance to electrolyte when laminating metals. The electrolyte contains LiPF ６ The trivalent chromium compound (A) may contain fluorine compounds such as the above. Fluorine compounds react with water to produce hydrofluoric acid, which corrodes metals such as aluminum. The trivalent chromium compound (A) can form a coating that is highly resistant to the above-mentioned electrolyte solution.

[0022] The trivalent chromium compound (A) is not particularly limited, but examples thereof include chromium(III) fluoride, chromium(III) nitrate, chromium(III) phosphate, chromium(III) acetate, chromium(III) chloride, chromium(III) sulfate, chromium(III) oxalate, chromium(III) formate, chromium(III) hydroxide, chromium(III) oxide, chromium(III) bromide, and chromium(III) iodide.

[0023] The content of the trivalent chromium compound (A), calculated as the trivalent chromium content (chromium concentration) of the trivalent chromium compound (A), is preferably 5% to 15% of the total solid content of the aqueous surface treatment agent. This improves the electrolyte resistance when laminating onto metal. The trivalent chromium concentration in the aqueous surface treatment agent is more preferably 5% to 10%.

[0024] The concentration of the trivalent chromium compound (A) in the aqueous surface treatment agent is preferably 0.1% or more and 0.45% or less in terms of the trivalent chromium contained in the trivalent chromium compound (A) (chromium concentration). This allows for improved electrolyte resistance when laminating onto metal. The trivalent chromium concentration in the aqueous surface treatment agent is more preferably 0.15% or more and 0.45% or less.

[0025] (Water-soluble or Water-dispersible Acrylic Resin (B)) When contained in an aqueous surface treatment agent, the water-soluble or water-dispersible acrylic resin (B) improves adhesion when laminating metal. The water-soluble or water-dispersible acrylic resin (B) contains, for example, a structural unit derived from a monomer having a carboxyl group. The monomer having a carboxyl group is not particularly limited, but examples thereof include (meth)acrylic acid, crotonic acid, isocrotonic acid, (meth)acrylic acid dimer, and an ε-caprolactone adduct of (meth)acrylic acid. Other examples of monomers having a carboxyl group include unsaturated dibasic acids such as maleic acid, fumaric acid, and itaconic acid, as well as their half esters, half amides, and half thioesters, and two or more of these may be used in combination.

[0026] The water-soluble or water-dispersible acrylic resin (B) is preferably poly(meth)acrylic acid, more preferably polyacrylic acid, from the viewpoint of electrolyte resistance when laminating metal.

[0027] Commercially available polyacrylic acids include Jurrimer AC-10L, AC-10H, AC-20L, and SH-5 (all manufactured by Toagosei Co., Ltd.).

[0028] The water-soluble or water-dispersible acrylic resin (B) may further contain a structural unit derived from a monomer having a hydroxyl group.

[0029] The monomer having a hydroxyl group is not particularly limited, but examples thereof include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, glycerin mono(meth)acrylate, (meth)allyl alcohol, N-methylol (meth)acrylamide, N-(2-hydroxyethyl)acrylamide, N-(2-hydroxypropyl)acrylamide, and ε-caprolactone adducts of 2-hydroxyethyl (meth)acrylate, and two or more of these may be used in combination.

[0030] The water-soluble or water-dispersible acrylic resin (B) may further contain structural units derived from monomers other than those mentioned above (other monomers).

[0031] The other monomers are not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, 1-methylethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyl (meth)acrylate, and methoxypolyethylene (meth)acrylate. Examples of other monomers besides the above include styrene, α-methylstyrene, vinyl ketone, t-butylstyrene, p-chlorostyrene, vinylnaphthalene, acrylonitrile, methacrylonitrile, ethylene, propylene, vinyl acetate, vinyl propionate, butadiene, and isoprene, and two or more of these may be used in combination.

[0032] The weight-average molecular weight of the water-soluble or water-dispersible acrylic resin (B) is 50,000 or more and 1,000,000 or less. This allows for the formation of a coating with excellent adhesion and electrolyte resistance. The weight-average molecular weight of the water-soluble or water-dispersible acrylic resin (B) is preferably 50,000 or more and 250,000 or less. If the weight-average molecular weight of the water-soluble or water-dispersible acrylic resin (B) is less than 50,000, the adhesion of the laminate film decreases when laminating to metal, while if it exceeds 1,000,000, the aqueous surface treatment agent is prone to gelation, making handling difficult.

[0033] In this specification and claims, the weight average molecular weight of the water-soluble or water-dispersible acrylic resin (B) is a molecular weight determined by the GPC method using polyethylene oxide as a standard substance.

[0034] The water-soluble or water-dispersible acrylic resin (B) has an acid value of more than 740 mgKOH / g of solid content, which allows the formation of a coating having excellent adhesion and electrolyte resistance. The water-soluble or water-dispersible acrylic resin (B) may have an acid value of 779 mgKOH / g or less of solid content.

[0035] In this specification and claims, the acid value of the solid content of the water-soluble or water-dispersible acrylic resin (B) refers to a theoretical value of the acid value of the solid content, calculated by calculating the amount of potassium hydroxide (unit: mg) required to neutralize the acid groups contained in 1 g of the solid content of the acrylic resin based on the charge ratio of each monomer used in the polymerization of the acrylic resin. The acid value of the solid content of the water-soluble or water-dispersible acrylic resin (B) can be controlled to a desired value by adjusting the type and charge ratio of each monomer constituting the monomer composition used in the polymerization.

[0036] (Phosphate Compound (C)) When contained in an aqueous surface treatment agent, the phosphate compound (C) improves electrolyte resistance when laminating metals. The phosphate compound (C) is not particularly limited, but examples thereof include phosphoric acid, condensed phosphoric acid, phosphate salts, condensed phosphate salts, etc., and two or more types may be used in combination. Among these, phosphoric acid is preferred. Examples of condensed phosphoric acid include pyrophosphoric acid, tripolyphosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, and ultraphosphoric acid. Examples of salts of phosphate salts or condensed phosphate salts include alkali metal salts and ammonium salts.

[0037] The ratio of the solid mass of the phosphate compound (C) to the total solid mass of the aqueous metal surface treatment agent is preferably 5% or more and 40% or less in terms of phosphate ions. This allows for improved electrolyte resistance when laminating onto metal. The content of the phosphate compound (C) in the aqueous surface treatment agent is more preferably 10% or more and 40% or less.

[0038] The concentration of the phosphate compound (C) in the aqueous metal surface treatment agent is preferably 0.2% or more and 0.8% or less in terms of phosphate ions. This improves the electrolyte resistance when laminating metal. The concentration of the phosphate compound (C) in the aqueous surface treatment agent is more preferably 0.2% or more and 0.5% or less.

[0039] (Nitrate ions (D)) Nitrate ions (D) are preferably contained in the aqueous metal surface treatment agent as counter ions of trivalent chromium in the trivalent chromium compound (A). The inclusion of nitrate ions (D) and / or phosphate ions in the aqueous metal surface treatment agent can improve the corrosion resistance and adhesion of the coating formed. For example, when chromium (III) nitrate is used as the trivalent chromium compound (A), chromium (III) nitrate can serve as a source of nitrate ions (D). In addition to the above, a substance that can serve as a source of nitrate ions (D) may be blended into the aqueous surface treatment agent. Examples of such substances include nitric acid. When chromium (III) nitrate is used as the trivalent chromium compound (A), it is preferred that chromium (III) nitrate be the only source of nitrate ions (D).

[0040] When the aqueous surface treatment agent according to this embodiment contains nitrate ions (D), the molar ratio (A / D) of the trivalent chromium compound (A) to the nitrate ions (D) is preferably 0.3 or more and 0.4 or less. If the molar ratio (A / D) is less than 0.3, there may be an excess of nitrate ions, which may result in poor adhesion, whereas if the molar ratio (A / D) is more than 0.4, there may be an insufficient amount of nitrate ions, which are counter ions necessary to stabilize trivalent chromium, which may result in a loss of solution stability and a tendency for precipitation to occur.

[0041] The concentration of nitrate ions (D) in the aqueous metal surface treatment agent is preferably 0.3% or more and 1.7% or less, thereby ensuring solution stability and electrolyte resistance. The concentration of nitrate ions (D) in the aqueous surface treatment agent is more preferably 0.5% or more and 1.6% or less.

[0042] The pH of the aqueous surface treatment agent of the present embodiment is not particularly limited, but is, for example, 1 or more and 4 or less.

[0043] (Other Components) The water content in the aqueous surface treatment agent of this embodiment is not particularly limited, but is, for example, 50% by mass or more and 99.9% by mass or less. Furthermore, the aqueous surface treatment agent may further contain a water-miscible organic solvent, as necessary, in order to adjust the solid content concentration or drying speed. Examples of water-miscible organic solvents include, but are not particularly limited to, ketone-based solvents such as acetone and methyl ethyl ketone; amide-based solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, and 1-methoxy-2-propanol; ether-based solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone-based solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone.

[0044] The aqueous surface treatment agent of the present embodiment may further contain known additives such as a crosslinking agent, a surface conditioner, an antifoaming agent, a plasticizer, an antioxidant, an antibacterial agent, and a colorant, as needed.

[0045] [Surface-Treated Metal] By surface treating a metal with the aqueous surface treatment agent of this embodiment, a surface-treated metal having a coating formed on the surface can be obtained. The shape of the metal is not particularly limited, but examples include foil and plate shapes. When using a foil- or plate-shaped metal, one side may be surface-treated with the aqueous surface treatment agent of this embodiment, or both sides may be surface-treated with the aqueous surface treatment agent of this embodiment. Furthermore, when both sides are surface-treated with the aqueous surface treatment agent of this embodiment, both sides may be surface-treated with the same aqueous surface treatment agent, or both sides may be surface-treated with different aqueous surface treatment agents.

[0046] The surface-treated metal of this embodiment may be a metal having a coating that has been laminated. That is, a laminate film may be adhered to a coating formed by surface-treating the metal. When a foil-shaped or plate-shaped metal is used, a laminate film may be adhered to one side, or may be adhered to both sides. Furthermore, when a laminate film is adhered to both sides, the same laminate film may be adhered to both sides, or different laminate films may be adhered to both sides.

[0047] The material constituting the laminate film is not particularly limited, but examples thereof include polyethylene-based resins, polypropylene-based resins, polycarbonate-based resins, polyvinyl alcohol-based resins, polyvinyl acetal-based resins, polyvinylidene chloride-based resins, polyvinyl acetate-based resins, polyethylene terephthalate-based resins, polyethylene naphthalate-based resins, polybutylene terephthalate-based resins, polyethylene isophthalate-based resins, copolymer polyester-based resins, polyester-based resins, polyamide-based resins, polyimide-based resins, polyetherimide-based resins, polyphenylene sulfide-based resins, fluorine-based resins, silicone-based resins, nylon-based resins, phenol-based resins, (meth)acrylic-based resins, epoxy-based resins, and polymetaxylylene azibamide-based resins, and two or more of these may be used in combination.

[0048] The laminate film may be a single-layer film or a multilayer film. The multilayer film may be formed by laminating multiple films with or without an adhesive. The adhesive may be a one-component curing adhesive or a two-component curing adhesive. Examples of resin components constituting the adhesive include polyester resins, polyether resins, polyurethane resins, epoxy resins, phenolic resins, polyamide resins, polyolefin resins, polyvinyl acetate resins, cellulose resins, (meth)acrylic resins, polyimide resins, amino resins, rubber, and silicone resins. The method for laminating multiple films without an adhesive is not particularly limited, but examples include coextrusion, sand lamination, and thermal lamination.

[0049] The surface-treated metal of this embodiment may have a layer other than the coating and the laminate film (hereinafter referred to as "other layer"). The other layer may be present between the coating and the laminate film, or may be present on the laminate film. Furthermore, the surface-treated metal of this embodiment may have another layer on the coating without the laminate film adhering to the metal having the coating.

[0050] The other layers are not particularly limited, but examples thereof include known layers such as an adhesive layer, a coating film, a hard coat layer, an antifouling layer, an antiglare layer, a design layer, a printed layer, a polarizing plate, a colored layer, a liquid crystal layer, a light guide plate, a transparent conductive film, and a spacer, and two or more of these may be used in combination.

[0051] The adhesive layer may be formed from a one-component adhesive or a two-component adhesive.

[0052] Resins constituting the adhesive that can be used to form the adhesive layer include polyolefin resins, polyester resins, polyether resins, polyurethane resins, polycarbonate resins, epoxy resins, phenolic resins, polyamide resins, polyvinyl acetate resins, cellulose resins, (meth)acrylic resins, polyimide resins, amino resins, chloroprene rubber resins, nitrile rubber resins, styrene-butadiene rubber resins, silicone resins, fluorinated ethylene-propylene copolymer resins, etc., and two or more of these may be used in combination. Examples of combinations of resins that can be used in combination include polyurethane resins and modified polyolefin resins, polyamide resins and acid-modified polyolefin resins, polyamide resins and metal-modified polyolefin resins, polyamide resins and polyester resins, polyester resins and acid-modified polyolefin resins, polyester resins and metal-modified polyolefin resins, etc.

[0053] The polyolefin resin includes an acid-modified polyolefin resin and a metal-modified polyolefin resin. Examples of the acid-modified polyolefin resin include a polyolefin resin modified with an unsaturated carboxylic acid or an anhydride thereof, such as maleic anhydride-modified polypropylene. Commercially available acid-modified polypropylene resins include Admer (NB508, NF518, LB548, QB510, QB550, LB458, NF528, LF128, LF308, NF308, NF548, NF558, SF600, SF700, SF731, SF715, SE800, NE060, NE065, NE090, XE070, HE040, QE060, QF500, QF551, QF570, NR106, NS101, etc.) manufactured by Mitsui Chemicals, and Unistall (R-200X, R-303XE, E-200EM, A-200EM, etc.) manufactured by Mitsui Chemicals. 00PM, A-201PM, H-100, H-200, XP01A, XP01B / 11B, XP03F, XP04A, etc.), Modic (P502, P512VB, P553A, P674V, P565, P555, P908H511, H503, H514, L502, L504, M142, M512, M522, M545, A543, F502, F573, F534A, etc.) manufactured by Mitsubishi Chemical, Arrowbase (SB-1200, SE-1200, SD-1200, DA1010, DC-1010, YA-6010, etc.) manufactured by Unitika, etc.

[0054] The method for forming the adhesive layer is not particularly limited, but examples thereof include an extrusion molding method and a dispersion method.

[0055] Examples of uses of the surface-treated metal of this embodiment include battery exterior materials, food packaging materials, food can bodies or lids, beverage can bodies or lids, soft packaging materials or surface protection materials containing metal foil such as aluminum pouches, battery separators, tab leads, condenser cases, heat exchangers, electronic device housings, metal building materials, vehicle bodies, engine parts or chassis parts, aircraft bodies, main wings, frames, fuel tanks, engine turbines, engine fans or parts, railway vehicle bodies, bogies or parts, ships, rocket parts, bicycle parts, vending machines, elevator car side panels, governors or hoists, escalator steps or interior panels, machine tools, injection molding machines, structural members or drive members for industrial robots, semiconductor manufacturing equipment, displays, submarines, traffic lights, automatic looms, tunnel boring machines, pipelines, road signs, generators, waste incinerators, exhaust gas treatment devices, motors, transformers, electronic circuits, light bulbs, photomultiplier tubes, golf clubs, antennas, bolts, nuts, screws, and the like. Among these, from the viewpoint of electrolyte resistance, a battery packaging material is preferred, and a lithium ion battery packaging material is particularly preferred.

[0056] [Method for Manufacturing Metal Foil Laminate] The method for manufacturing a metal foil laminate according to this embodiment includes a surface treatment step and a lamination step.

[0057] (Surface Treatment Step) The surface treatment step is, for example, a step of applying the aqueous surface treatment agent of the above embodiment to at least one surface of the prepared metal foil, followed by drying.

[0058] The method for applying the aqueous surface treatment agent of the present embodiment is not particularly limited, and examples thereof include roll coater coating, gravure coater coating, reverse coater coating, slot die coater coating, lip coater coating, knife coater coating, blade coater coating, chamber doctor coater coating, air knife coater coating, curtain coat coating, spin coat coating, brush coating, roller coating, bar coater coating, dip coating, applicator coating, spray coating, flow coating, and combinations thereof.

[0059] The drying method is not particularly limited, and known methods can be used, including heat drying methods such as drying using an oven, drying by forced circulation of hot air, and drying in an electromagnetic induction heating furnace using an IH heater or the like. The conditions for the heat drying method can be, for example, a temperature of 40°C or higher and 230°C or lower for 2 seconds or longer and 180 seconds or shorter. Here, the conditions set during heat drying, such as air volume and air speed, can be set as desired.

[0060] In the surface treatment step, the aqueous surface treatment agent of the present embodiment may be applied to the surface of the metal foil while drying it. For example, the aqueous surface treatment agent of the present embodiment may be applied to the surface of a preheated metal foil and then dried.

[0061] The amount of film formed after drying in the surface treatment process is 0.1 mg / m ２ 5000mg / m or more ２ Preferably, it is 1 mg / m or less. ２ 500mg / m or more ２ More preferably, it is:

[0062] (Laminating step) The laminating step is a step of laminating a film on the surface of the metal foil treated by the surface treatment step. The laminating method is not particularly limited, but known methods such as dry lamination, heat lamination, and extrusion lamination can be used.

[0063] The method for producing a metal foil laminate according to this embodiment may include steps other than those described above, as long as the effects of the present invention are not impaired.

[0064] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0065] [Preparation of Aqueous Metal Surface Treatment Agents] The aqueous metal surface treatment agents according to each Example and Comparative Example were prepared by mixing each component with pure water in the amounts shown in Table 1. In Table 1, (A) refers to the trivalent chromium compound (A), and the content refers to the mass ratio (mass %) of trivalent chromium to the total solid content of the aqueous metal surface treatment agent. Similarly, (B) refers to a resin such as a water-soluble or water-dispersible acrylic resin (B), and the content refers to the mass ratio (mass %) to the total solid content of the aqueous metal surface treatment agent. Similarly, (C) refers to the phosphate compound (C), and the content refers to the mass ratio (mass %) of the solid content as phosphate ions to the total solid content of the aqueous metal surface treatment agent. (A / D) refers to the molar ratio (A / D) of the trivalent chromium compound (A) to nitrate ions (D).

[0066] In each of the Examples and Comparative Examples, a 35% chromium nitrate solution was used as the trivalent chromium compound (A). A 75% aqueous phosphoric acid solution was used as the phosphate compound (C). In Comparative Example 9, nitric acid was also used as a source of nitrate ions (D).

[0067] The definitions of the abbreviations in Table 1 are as follows: B1: Jurrimer AC-10L (manufactured by Toagosei Co., Ltd.) Polyacrylic acid, weight average molecular weight 50,000, solid acid value 779 mg KOH / g B2: Wako Pure Chemical Industries, Ltd. Polyacrylic acid, weight average molecular weight 250,000, solid acid value 779 mg KOH / g B3: Jurrimer AC-10H (manufactured by Toagosei Co., Ltd.) Polyacrylic acid, weight average molecular weight 800,000, solid acid value 779 mg KOH / g B4: Jurrimer AC-10H (manufactured by Toagosei Co., Ltd.) Polyacrylic acid, weight average molecular weight 3,000,000, solid acid value 779 mg KOH / g B5: Aron A-10SL (manufactured by Toagosei Co., Ltd.) Polyacrylic acid, weight average molecular weight 5,000, solid acid value 779 mg KOH / g B6: Arialic HL-415 (manufactured by Nippon Shokubai Co., Ltd.) Polyacrylic acid Weight average molecular weight 10,000 Acid value of solid content 779 mgKOH / g B7: Haricoat G-51 (Harima Chemicals) Acrylamide B8: PVA-HC (Kuraray) Polyvinyl alcohol B9: A-12SL (Toagosei) Sulfonic acid copolymer B10: Addibond 021 (Solvay) Phosphonic acid-modified acrylic acid B11: K-30 (Nippon Shokubai) Polyvinylpyrrolidone

[0068] [Coating of aqueous metal surface treatment agent (surface treatment)] The aqueous metal surface treatment agent according to each of the examples and comparative examples prepared above was applied to an aluminum foil using a 0.8 nylon bar (bar coater), followed by baking at 190°C for 2 minutes.

[0069] [Dry lamination (lamination)] XP01A (modified polyolefin, manufactured by Mitsui Chemicals) and D-370N (isocyanate, manufactured by Mitsui Chemicals) were mixed and stirred at a mass ratio of 100:0.59 to prepare an adhesive liquid. Next, the adhesive liquid was applied to each sample coated with the aqueous metal surface treatment agent using a #20 stainless steel bar (bar coater). After that, baking was performed at 100°C for 60 seconds to form an adhesive layer. A CPP film was placed on the prepared sample, sandwiched between PET films, and passed through a laminator for heat and pressure bonding. After that, the sample was aged at 60°C for 3 days to obtain samples according to each example and comparative example.

[0070] <Evaluation> [Peel Strength Test (Initial) (Adhesion of Laminate Film)] Samples according to each Example and Comparative Example were adjusted to a width of 15 mm, and a cut was made with a cutter from the back surface at a location approximately 1 cm below the adhesive portion of the film, and the sample was folded. Next, the film at the folded portion was pulled approximately 2 mm in the direction of the remainder of the sample (180° direction), and the seal strength (N / 15 mm) was measured to evaluate adhesion. For the test, a tension-compression tester: LST-200N-S100 (manufactured by MinebeaMitsumi Inc.) was used. Measurements were performed with n=2, and the average values ​​are shown in Table 1.

[0071] [Peel strength test (electrolyte) (electrolyte resistance)] 1M LiPF ６ A test electrolyte was prepared by adding 10,000 ppm of deionized water to an electrolyte solution in which the above was dissolved in an ethylene carbonate / dimethyl carbonate / diethyl carbonate mixed solvent (volume ratio 1 / 1 / 1). The samples according to the above examples and comparative examples were immersed in the test electrolyte at 85°C for one day, and then the peel strength was measured in the same manner as above to evaluate the electrolyte resistance. Note that the film of the sample of comparative example 8 was completely peeled off, making it impossible to measure the peel strength.

[0072] [Handling] The aqueous metal surface treatment agents according to each Example and Comparative Example were prepared, left to stand at room temperature for one day, and then visually inspected for the presence or absence of gelation and precipitation. The cases where neither gelation nor precipitation occurred were rated as "pass", and the cases where gelation or precipitation occurred were rated as "fail". The results are shown in Table 1 as "pass" (A) or "fail" (B).

[0073]

[0074] The results shown in Table 1 show that when a metal plate is surface-treated with the aqueous surface treatment agent according to each Example, the adhesion and electrolyte resistance of the laminate film of the laminated metal plate are higher than when the metal plate is surface-treated with the aqueous surface treatment agent according to each Comparative Example. Note that the aqueous surface treatment agent according to Comparative Example 1 produced a laminate film with high adhesion and electrolyte resistance, but the handling was poor and the film was not suitable for practical use.

Claims

1. An aqueous metal surface treatment agent for use in metal surface treatment, comprising a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), wherein the water-soluble or water-dispersible acrylic resin (B) has a weight average molecular weight of 50,000 or more and 1,000,000 or less, and an acid value of the solid content exceeds 740 mg KOH / g.

2. The aqueous metal surface treatment agent according to claim 1, wherein the mass ratio of trivalent chromium contained in said trivalent chromium compound (A) to the total solid content of said aqueous metal surface treatment agent is 5% or more and 15% or less in terms of trivalent chromium, and the mass ratio of solid content of said phosphate compound (C) to the total solid content of said aqueous metal surface treatment agent is 5% or more and 40% or less in terms of phosphate ion.

3. The aqueous metal surface treatment agent according to claim 1 or 2, further comprising nitrate ions (D), and a molar ratio (A / D) of the trivalent chromium compound (A) to the nitrate ions (D) is 0.3 or more and 0.4 or less.

4. A method for producing a metal foil laminate, comprising: a surface treatment step of treating at least one surface of a metal foil; and a lamination step of laminating a film onto the surface of the metal foil treated by the surface treatment step, wherein the aqueous metal surface treatment agent used in the surface treatment step comprises a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), and the water-soluble or water-dispersible acrylic resin (B) has a weight average molecular weight of 50,000 or more and 1,000,000 or less and an acid value of the solid content exceeds 740 mg KOH / g.

5. A method for producing a metal foil laminate as described in claim 4, wherein the mass ratio of trivalent chromium contained in the trivalent chromium compound (A) to the total solid content of the aqueous metal surface treatment agent is 5% or more and 15% or less in terms of trivalent chromium, and the mass ratio of solid content of the phosphate compound (C) to the total solid content of the aqueous metal surface treatment agent is 5% or more and 10% or less in terms of phosphate ion.

6. The method for producing a metal foil laminate according to claim 4 or 5, wherein the aqueous metal surface treatment agent further contains nitrate ions (D), and the molar ratio (A / D) of the trivalent chromium compound (A) to the nitrate ions (D) is 0.3 or more and 0.4 or less.

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