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

Abstract

The present invention provides an aqueous surface treatment agent capable of improving adhesion and electrolyte resistance when laminating metals. [Solution] An aqueous metal surface treatment agent used for metal surface treatment comprises a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), in which 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 mgKOH / g.

Description

[Technical field]

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

[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 beauty 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] As a method for forming a chemical conversion coating layer on an aluminum surface, for example, a method using a surface treatment agent containing a water-soluble trivalent chromium compound and a water-soluble organic polymer compound is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 53-037550 Summary of the Invention [Problem to be solved by the invention]

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

[0007] An object of the present invention is to provide an aqueous surface treatment agent capable of improving adhesion and electrolyte resistance when laminating metals. [Means for solving the problem]

[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 mg KOH / g.

[0009] (2) The aqueous metal surface treatment agent according to (1), 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 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 in terms of phosphate ion.

[0010] (3) The aqueous metal surface treatment agent according to (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.

[0011] (4) The present disclosure also relates to a method for producing a metal foil laminate, the method comprising: 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 by the surface treatment step, wherein an 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 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% 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 40% or less in terms of phosphate ion.

[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 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. Effect of the Invention

[0014] According to the present invention, it is possible to provide an aqueous surface treatment agent capable of improving adhesion and electrolyte resistance when laminating metals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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] [Water-based 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, and examples thereof include iron, zinc, aluminum, copper, nickel, and the like, and two or more of them may be used in combination. That is, the metal may be an alloy. The alloy components may include, for example, carbon, nitrogen, oxygen, phosphorus, sulfur, silicon, manganese, chromium, titanium, molybdenum, and the like. Among these, from the viewpoint of processability and adhesion, aluminum or an aluminum alloy, iron or an iron alloy, or copper or a copper alloy is preferable, and aluminum or an aluminum alloy is more preferable. 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, aluminum die-cast (ADC material), and the like. When the surface-treated metal of the present embodiment described later 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 metals such as nickel, zinc, chromium, iron, tin, copper, silver, platinum, and gold, and two or more metals may be used in combination. Examples of the plating method include electroplating, electroless plating, hot-dip plating, vacuum deposition, sputtering, and ion plating. Examples of the plated metal include Ni-plated steel, Ni-plated copper, Zn-plated steel, and Zn-Ni-plated steel. Examples of the plated metal (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). It is preferable that the aqueous metal surface treatment agent further contains nitrate ions (D).

[0020] The aqueous surface treatment agent of the present embodiment may contain hexavalent chromium. In this case, the content of hexavalent chromium in the aqueous surface treatment agent of the present 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 the present embodiment is preferably minimized, that is, a trace amount, and most preferably 0 mass%. The film formed by surface treating a metal with the aqueous surface treatment agent of the present embodiment preferably does not substantially contain hexavalent chromium, and most preferably does not contain hexavalent chromium.

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

[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) is preferably 5% or more and 15% or less of the total solid content of the aqueous surface treatment agent in terms of trivalent chromium contained in the trivalent chromium compound (A) (chromium concentration). This can improve the electrolyte resistance when laminating to metal. The trivalent chromium concentration in the aqueous surface treatment agent is more preferably 5% or more and 10% or less.

[0024] The concentration of the trivalent chromium compound (A) is preferably 0.1% or more and 0.45% or less in the aqueous surface treatment agent in terms of the trivalent chromium contained in the trivalent chromium compound (A) (chromium concentration). This can improve the electrolyte resistance when laminating to 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)) The water-soluble or water-dispersible acrylic resin (B) improves adhesion when laminating metal by being contained in the aqueous surface treatment agent. 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 ε-caprolactone adduct of (meth)acrylic acid. Other monomers having a carboxyl group include unsaturated dibasic acids such as maleic acid, fumaric acid, and itaconic acid, and their half esters, half amides, and half thioesters, and two or more of them 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 in laminating metal.

[0027] Commercially available polyacrylic acids include Julimer 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] Examples of the other monomers include, but are not limited to, 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 those mentioned above include styrene, α-methylstyrene, vinyl ketone, t-butylstyrene, p-chlorostyrene, vinylnaphthalene, acrylonitrile, methacrylonitrile, ethylene, propylene, vinyl acetate, vinyl propionate, butadiene, isoprene, and the like, 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 the formation of a film 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 a metal, and 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. This allows the formation of a coating film with 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.

[0035] In this specification and claims, the acid value of the solid content of the water-soluble or water-dispersible acrylic resin (B) means 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)) The phosphoric acid compound (C) is contained in the aqueous surface treatment agent, and improves the electrolyte resistance when laminating metal. The phosphoric acid compound (C) is not particularly limited, but examples thereof include phosphoric acid, condensed phosphoric acid, phosphates, condensed phosphates, etc., and two or more of them 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, ultraphosphoric acid, etc. Examples of salts in phosphates or condensed phosphates include alkali metal salts, ammonium salts, etc.

[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 as phosphate ions. This can improve the electrolyte resistance when laminating to 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 phosphoric acid compound (C) in the aqueous metal surface treatment agent is preferably 0.2% or more and 0.8% or less as phosphate ions. This can improve the electrolyte resistance when laminating to metal. The concentration of the phosphoric acid compound (C) in the aqueous surface treatment agent is more preferably 0.2% or more and 0.5% or less.

[0039] (Nitrate ion (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 film formed. For example, when chromium nitrate (III) is used as the trivalent chromium compound (A), chromium nitrate (III) can be a source of nitrate ions (D). In addition to the above, a substance that can be a source of nitrate ions (D) may be blended into the aqueous surface treatment agent. Examples of such substances include nitric acid. When chromium nitrate (III) is used as the trivalent chromium compound (A), it is preferable that the source of nitrate ions (D) is only chromium nitrate (III).

[0040] When the aqueous surface treatment agent according to the present 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. When the molar ratio (A / D) is less than 0.3, there is a risk that the amount of nitrate ions will be excessive, resulting in poor adhesion, and when the molar ratio (A / D) is more than 0.4, there is a risk that the amount of nitrate ions, which are counter ions necessary for stabilizing trivalent chromium, will be insufficient, resulting in loss of liquid stability and making precipitation more likely 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. This ensures the 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 Ingredients) The content of water in the aqueous surface treatment agent of the present embodiment is not particularly limited, but is, for example, 50% by mass or more and 99.9% by mass or less. In addition, the aqueous surface treatment agent may further contain an organic solvent miscible with water, as necessary, in order to adjust the solid content concentration and drying speed. The organic solvent miscible with water is not particularly limited, but examples thereof include 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, a defoamer, a plasticizer, an antioxidant, an antibacterial agent, and a colorant, as necessary.

[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 thereof include foil and plate shapes. When using a foil-shaped 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. 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 is laminated. That is, a laminate film may be attached to the coating formed by surface-treating the metal. When a foil-like or plate-like metal is used, a laminate film may be attached to one side, or a laminate film may be attached to both sides. In addition, when a laminate film is attached to both sides, the same laminate film may be attached to both sides, or different laminate films may be attached to both sides.

[0047] Materials constituting the laminate film are 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 resins, epoxy-based resins, polymetaxylylene azibamide-based resins, and the like, and two or more of these may be used in combination.

[0048] As the laminate film, a single layer film or a multilayer film may be used. The multilayer film may be a laminate of a plurality of films with an adhesive interposed therebetween, or may be a laminate of a plurality of films without an adhesive interposed therebetween. The adhesive may be a one-liquid curing adhesive or a two-liquid curing adhesive. Examples of the resin components constituting the adhesive include polyester resins, polyether resins, polyurethane resins, epoxy resins, phenol resins, polyamide resins, polyolefin resins, polyvinyl acetate resins, cellulose resins, (meth)acrylic resins, polyimide resins, amino resins, rubber, and silicone resins. Methods for laminating a plurality of films without an adhesive interposed therebetween are not particularly limited, and examples thereof include a co-extrusion method, a sand lamination method, and a thermal lamination method.

[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. In addition, 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 layers may be used in combination.

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

[0052] Examples of the 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, phenol 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 them may be used in combination. Examples of the combination 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 polyolefin resins 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 ... 00PM, A-201PM, H-100, H-200, XP01A, XP01B / 11B, XP03F, XP04A, etc.), Modic manufactured by Mitsubishi Chemical (P502, P512VB, P553A, P674V, P565, P555, P908H511, H503, H514, L502, L504, M142, M512, M522, M545, A543, F502, F573, F534A, etc.), Arrowbase manufactured by Unitika (SB-1200, SE-1200, SD-1200, DA1010, DC-1010, YA-6010, etc.), 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 applications of the surface-treated metal of this embodiment include exterior materials for batteries, food packaging materials, bodies or lids for food cans, bodies or lids for beverage cans, 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, railroad car bodies, bogies or parts, ships, rocket parts, bicycle parts, vending machines, elevator car side panels, speed 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, signals, 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, exterior materials for batteries are preferred, and exterior materials for lithium ion batteries are particularly preferred.

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

[0057] (Surface treatment process) 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, and then drying the applied surface.

[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, such as a heat drying method using an oven, a drying method by forced circulation of hot air, and a drying method using an electromagnetic induction heating furnace using an IH heater or the like. The heat drying method can be performed under conditions of, for example, a temperature of 40° C. or higher and 230° C. or lower for 2 seconds or longer and 180 seconds or shorter. The conditions such as the air volume and air speed set during heat drying can be set arbitrarily.

[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. 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 More than 5000mg / m 2 It is preferable that the concentration is less than 1 mg / m 2 More than 500mg / m 2 It is more preferable that:

[0062] (Lamination process) The lamination step is a step of laminating a film on the surface of the metal foil treated by the surface treatment step. The lamination method is not particularly limited, but may be any known method such as a dry lamination method, a heat lamination method, or an extrusion lamination method.

[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. EXAMPLES

[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 agent] The aqueous metal surface treatment agents according to each of the Examples and Comparative Examples were prepared by mixing each component with pure water in the amounts shown in Table 1. In Table 1, (A) means the trivalent chromium compound (A), and the content means the ratio (mass%) of the mass of trivalent chromium to the total solid content of the aqueous metal surface treatment agent. Similarly, (B) means a resin such as a water-soluble or water-dispersible acrylic resin (B), and the content means the ratio (mass%) of the mass to the total solid content of the aqueous metal surface treatment agent. Similarly, (C) means a phosphate compound (C), and the content means the ratio (mass%) of the solid content as phosphate ions to the total solid content of the aqueous metal surface treatment agent. (A / D) means the molar ratio (A / D) of the trivalent chromium compound (A) and 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 phosphoric acid 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: Jurimer AC-10L (manufactured by Toagosei) Polyacrylic acid Weight average molecular weight 50,000 Solid content acid value 779 mg KOH / g B2: Polyacrylic acid manufactured by Wako Pure Chemical Industries, Ltd. Weight average molecular weight 250,000, solid acid value 779 mg KOH / g B3: Jurimer AC-10H (manufactured by Toagosei) Polyacrylic acid Weight average molecular weight 800,000 Solid content acid value 779 mg KOH / g B4: Jurimer AC-10H (manufactured by Toagosei) Polyacrylic acid Weight average molecular weight 3,000,000 Solid content acid value 779 mg KOH / g B5: Aron A-10SL (manufactured by Toagosei) Polyacrylic acid Weight average molecular weight 5,000 Solid content acid value 779 mg KOH / g B6: Arialic HL-415 (manufactured by Nippon Shokubai) Polyacrylic acid Weight average molecular weight 10,000 Solid content acid value 779 mg KOH / g B7: Haricoat G-51 (Harima Chemicals) Acrylamide B8: PVA-HC (Kuraray) Polyvinyl alcohol B9:A-12SL (manufactured by Toagosei) Sulfonic acid copolymer B10: Addibond 021 (Solvay) Phosphonic acid modified acrylic acid B11: K-30 (manufactured by Nippon Shokubai) Polyvinylpyrrolidone

[0068] [Coating of water-based metal surface treatment agents (surface treatment)] The aqueous metal surface treatment agents according to the Examples and Comparative Examples prepared above were applied to aluminum foil using a 0.8 nylon bar (bar coater), and then baked at 190° C. for 2 minutes.

[0069] [Dry lamination (lamination processing)] 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 above-mentioned aqueous metal surface treatment agent using a #20 stainless steel bar (bar coater). After that, the sample was baked 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 of the examples and comparative examples.

[0070] <Evaluation> [Peel strength test (initial stage) (adhesion of laminate film)] The samples of each Example and Comparative Example were adjusted to a width of 15 mm, and a cut was made with a cutter from the back side at a position about 1 cm below the film adhesion part, and the sample was folded. Next, the film of the folded part was pulled about 2 mm in the direction of the remaining part of the sample (180° direction), and the seal strength (N / 15 mm) was measured to evaluate the adhesion. For the test, a tension and compression tester: LST-200N-S100 (manufactured by MinebeaMitsumi Inc.) was used. The measurement was performed with n=2, and the average value is shown in Table 1.

[0071] [Peel strength test (electrolyte) (electrolyte resistance)] 1M LiPF 6 A test electrolyte was obtained by adding 10,000 ppm of deionized water to an electrolyte solution in which the above was dissolved in a mixed solvent of ethylene carbonate / dimethyl carbonate / diethyl carbonate (volume ratio 1 / 1 / 1). The samples according to the above examples and comparative examples were immersed in the test electrolyte solution 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, and the peel strength could not be measured.

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

[0073] [Table 1]

[0074] From the results shown in Table 1, it can be seen that when the 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, although the aqueous surface treatment agent according to Comparative Example 1 provided high adhesion and electrolyte resistance of the laminate film, the handling property was poor and it was not suitable for practical use.

Claims

1. An aqueous metal surface treatment agent for use in surface treatment of metals, comprising: A coating composition comprising a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), and does not contain colloidal silica; The content of hexavalent chromium in the aqueous metal surface treatment agent is less than 0.02% by mass, 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.

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

3. The aqueous metal surface treatment agent further contains nitrate ions (D), 3. The aqueous metal surface treatment agent according to claim 1, wherein 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 the steps of: a surface treatment step of treating at least one surface of the metal foil; A lamination step of laminating a film on the surface of the metal foil treated by the surface treatment step, the aqueous metal surface treatment agent used in the surface treatment step contains a trivalent chromium compound (A), a water-soluble or water-dispersible acrylic resin (B), and a phosphoric acid compound (C), and does not contain colloidal silica; The content of hexavalent chromium in the aqueous metal surface treatment agent is less than 0.02% by mass, 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.

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

6. The aqueous metal surface treatment agent further contains nitrate ions (D), 6. The method for producing a metal foil laminate according to claim 4, wherein 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.

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