JP2024090197A - Aqueous surface treatment agent and surface-treated metal - Google Patents

Abstract

To provide an aqueous surface treatment agent that can improve electrolyte resistance property of a surface-treated metal when it is used as a secondary battery tab lead or battery exterior material by being used for surface treatment of a metal.SOLUTION: An aqueous surface treatment agent used for surface treatment of a metal includes: (A) a cerium oxide sol; (B) an organic phosphorus compound including a phosphonic acid group and/or a phosphate group; and (C) an oxazoline group-containing resin.SELECTED DRAWING: None

Description

The present invention relates to an aqueous surface treatment agent and a surface-treated metal.

Metal sheets used in tab leads for secondary batteries are surface-treated to prevent the insulating seal of the tab lead from peeling off in the electrolyte. Similarly, laminate-type exterior materials for secondary batteries are surface-treated to prevent the metal foil and laminate film from peeling off in the electrolyte. Aqueous surface treatment agents are used for the surface treatment of such metals.

For example, Patent Document 1 describes a packing material for lithium batteries in which an adhesive layer, an aluminum foil layer, a coating layer, an adhesive resin layer, and a sealant layer are laminated in this order on one side of a base layer, the packing material being characterized in that the coating layer is a layer (A) in which 1 to 100 parts by mass of phosphoric acid or a phosphate is blended with 100 parts by mass of a rare earth element-based oxide.
Patent Document 2 describes an exterior material for lithium ion batteries in which an adhesive layer, an aluminum foil layer, a coating layer, an adhesive resin layer, and a sealant layer are laminated in this order on one side of a base layer, wherein the coating layer contains an anionic polymer (A), a crosslinking agent (B) that crosslinks the anionic polymer (A), a phosphorus compound (C) and a rare earth element-based oxide (D), and the ratio W1/W2 of the total content _W1 (mass%) of the anionic polymer (A) and the crosslinking agent (B) to the total content _W2 (mass%) _of the phosphorus compound (C) and the rare earth element-based oxide (D) _is 1 or less.
Patent Document 3 describes an exterior material for lithium ion batteries, which is composed of a laminate in which an adhesive layer, a base treatment layer containing the following components (A), (B), and (C) and in which the total amount of components (B) and (C) is 200 to 12,000 parts by mass relative to 100 parts by mass of component (A), an aluminum foil layer, a corrosion prevention treatment layer, an adhesive resin layer, and a sealant layer are laminated in this order on one side of a base layer. The laminate includes: (A) a crosslinked resin formed from a resin (A1) having two or more nitrogen-containing functional groups and a resin (A2) having a reactive functional group that reacts with the nitrogen-containing functional groups; (B) a rare earth element oxide; and (C) phosphoric acid or a phosphate.

JP 2008-210777 A JP 2011-065834 A International Publication No. 2014/181862

Here, when applying surface-treated metals to tab leads for secondary batteries or battery exterior materials, there is a problem in that it is necessary to improve electrolyte resistance in order to maintain excellent adhesion with insulating seals and laminate films even in environments where the metals come into contact with electrolyte.

The present invention aims to provide an aqueous surface treatment agent that can be used for the surface treatment of metals to improve electrolyte resistance when the surface-treated metal is used as a tab lead for a secondary battery or an exterior material for a battery.

The aqueous surface treatment agent according to the present invention comprises
An aqueous surface treatment agent for use in surface treatment of metals, comprising:
A cerium oxide sol (A),
an organophosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group;
an oxazoline group-containing resin (C);
The aqueous surface treatment agent comprises:

In one embodiment of the aqueous surface treatment agent according to the present invention, it is preferable that 50% or more of the solid content by mass of the resin component of the aqueous surface treatment agent is the oxazoline group-containing resin (C).

In one embodiment of the aqueous surface treatment agent according to the present invention, the organophosphorus compound (B) having a phosphonic acid group and/or a phosphate group preferably has a total of two or more phosphonic acid groups and/or phosphate groups in one molecule.

Furthermore, in one embodiment of the aqueous surface treatment agent according to the present invention, the organophosphorus compound (B) having a phosphonic acid group and/or a phosphate group is preferably phytic acid or a salt thereof.

The surface-treated metal according to the present invention is a surface-treated metal having a coating formed by surface-treating the metal with the aqueous surface treatment agent described above.

In one embodiment of the surface-treated metal according to the present invention, the metal is preferably aluminum or an aluminum alloy, or copper or a copper alloy.

In one embodiment of the surface-treated metal according to the present invention, the metal is preferably plated.

In one embodiment of the surface-treated metal according to the present invention, it is preferable that the metal having the coating has a polyolefin-based resin film layer on the coating.

In one embodiment, the surface-treated metal of the present invention may be a tab lead for a secondary battery.

In one embodiment of the surface-treated metal according to the present invention, it is preferable that the metal having the coating is laminated.

In one embodiment, the surface-treated metal of the present invention may be an exterior material for a battery.

The present invention provides an aqueous surface treatment agent that, when used for surface treatment of metals, can improve electrolyte resistance when the surface-treated metal is used as a tab lead for a secondary battery or an exterior material for a battery.

The following describes embodiments of the present invention. These descriptions are intended to be illustrative of the present invention and are not intended to limit the present invention in any way.

In the present invention, two or more embodiments may be combined in any manner.

In the present invention, the terms film and coating can be used interchangeably.

In the present invention, the term "solid content" is a concept that encompasses solid content, non-volatile content, and active ingredients.

In this specification, unless otherwise specified, numerical ranges are intended to include the upper and lower limits of the range. For example, 0.01 to 3% by mass means a range of 0.01% by mass or more and 3% by mass or less.

(Aqueous surface treatment agent)
The aqueous surface treatment agent according to the present invention comprises
An aqueous surface treatment agent for use in surface treatment of metals, comprising:
A cerium oxide sol (A),
an organophosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group;
an oxazoline group-containing resin (C);
The aqueous surface treatment agent according to the present invention may further contain another resin (D). The aqueous surface treatment agent according to the present invention may generally contain water. The aqueous surface treatment agent according to the present invention may further contain known additives such as a crosslinking agent, a surface conditioner, a defoamer, a plasticizer, an antioxidant, an antibacterial agent, a colorant, etc. The aqueous surface treatment agent according to the present invention may further contain an acid or a base for adjusting the pH.

Below, we will explain each component of the aqueous surface treatment agent according to the present invention.

Cerium oxide sol (A)
The cerium oxide sol (A) is a sol (colloid) in which cerium oxide (CeO ₂ ) is dispersed in a liquid dispersion medium (sometimes called a "solvent") at room temperature and normal pressure.
The average particle size of the cerium oxide may be preferably 1 nm or more, more preferably 3 nm or more, and preferably 500 nm or less, more preferably 50 nm or less.
Examples of dispersants for cerium oxide include water, organic acids, and phosphoric acid-based dispersants.
The pH of the cerium oxide sol (A) is preferably 2-10.
The cerium oxide content (concentration) of the cerium oxide sol (A) is preferably 1 wt % to 50 wt %.
The cerium oxide sol (A) may be used alone or in combination of two or more kinds.
Commercially available products of the cerium oxide sol (A) include, for example, "Needral B-10" (manufactured by Taki Chemical Industry Co., Ltd.), "Needral P-10" (manufactured by Taki Chemical Industry Co., Ltd.), "Needral U-15" (manufactured by Taki Chemical Industry Co., Ltd.), "CESL-15N" (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.), and "CESL-30N" (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.).

The average particle size of the cerium oxide sol (A) according to the present invention is a median size (D ₅₀ ) measured by a conventionally known measuring method such as a dynamic light scattering method. Specifically, it can be measured by using a dynamic light scattering photometer (DLS-8000 series) manufactured by Otsuka Electronics Co., Ltd.

By containing cerium oxide sol (A) in the aqueous surface treatment agent according to the present invention, the cerium oxide sol (A) does not dissolve in the electrolyte, and therefore the electrolyte resistance can be improved. On the other hand, water-soluble cerium compounds tend to dissolve in the electrolyte, and the desired electrolyte resistance cannot be achieved.

Examples of the organic phosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group include organic phosphorus compounds having a phosphonic acid group such as hydroxyethylidene diphosphonic acid (HEDP), nitrilotris(methylene phosphonic acid) (NTMP), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), ethylenediaminetetramethylenephosphonic acid (EDTMP), phenylphosphonic acid, and octylphosphonic acid, and organic phosphorus compounds having a phosphoric acid group such as phytic acid, O-phosphorylethanolamine, phosphoserine, and glycerophosphoric acid, and salts thereof. It is also possible to use these organic phosphorus compounds in combination. In order to improve electrolyte resistance, the organic phosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group is preferably an organic phosphorus compound having a total of two or more phosphonic acid groups and/or phosphoric acid groups in one molecule, and more preferably phytic acid or a salt thereof.

The aqueous surface treatment agent according to the present invention contains an organic phosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group, which allows cross-linking between the metal of the substrate and the cerium oxide sol (A) and between the cerium oxide sols (A), thereby improving electrolyte resistance. On the other hand, inorganic phosphoric acid compounds are easily hydrolyzed, and the cross-linking is broken in the electrolyte, so that the desired electrolyte resistance cannot be achieved.

From the viewpoint of improving electrolyte resistance, the solid content mass ratio ((A)/(B)) of the cerium oxide sol (A) to the organic phosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group in the aqueous surface treatment agent may be preferably 1 or more, more preferably 2.5 or more, and preferably 50 or less, more preferably 40 or less.

Oxazoline group-containing resin (C)
The oxazoline group-containing resin (C) is not particularly limited as long as it is a resin having an oxazoline group. The oxazoline group-containing resin (C) may be a resin having an oxazoline group as a side chain in a main chain having an arbitrary skeleton structure, and examples thereof include oxazoline group-containing resins having an acrylic main chain, oxazoline group-containing resins having a styrene/acrylic main chain, oxazoline group-containing resins having a styrene main chain, and oxazoline group-containing resins having an acrylonitrile/styrene main chain. Among them, oxazoline group-containing resins having an acrylic main chain are preferred from the viewpoint of excellent stability in aqueous solvents and colorless and transparent appearance after coating. For example, "Epocross WS series" (trade name, manufactured by Nippon Shokubai) is an example of an oxazoline group-containing resin having an acrylic main chain. The oxazoline value of the oxazoline group-containing resin is preferably 120 to 240 g (solid content)/equivalent. The number average molecular weight of the oxazoline group-containing resin is preferably 10,000 to 50,000. The number average molecular weight is determined by GPC using polystyrene as a standard.

By including the oxazoline group-containing resin (C) in the aqueous surface treatment agent according to the present invention, the oxazoline group-containing resin reacts with the carboxylic acid group, carboxylic anhydride, aromatic thiol group, phenol group, etc. contained in the insulating seal, laminate film, or adhesive layer to form a bond, thereby improving electrolyte resistance.

From the viewpoint of improving electrolyte resistance, the solid content mass ratio ((A)/(C)) of the cerium oxide sol (A) to the oxazoline group-containing resin (C) in the aqueous surface treatment agent may be preferably 0.5 or more, more preferably 1 or more, and preferably 50 or less, more preferably 40 or less.

Other resins (D)
The aqueous surface treatment agent according to the present invention may further contain other resins (D) (i.e., resins other than the oxazoline group-containing resin (C)). Examples of the other resins (D) include acrylic resins, polyester resins, alkyd resins, epoxy resins, urethane resins, phenolic resins, and melamine resins. The other resins (D) may be used alone or in combination of two or more.

The ratio of the mass of the oxazoline group-containing resin (C) to the mass of the solid content of the resin components of the aqueous surface treatment agent is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more, in order to improve electrolyte resistance.

Other Components and Characteristics of the Aqueous Surface Treatment Agent The aqueous surface treatment agent according to the present invention may generally contain water. The content of water in the aqueous surface treatment agent is not particularly limited, but is, for example, 50% by mass or more and 99.9% by mass or less.

The aqueous surface treatment agent according to the present invention may further contain known additives such as crosslinking agents, surface conditioners, defoamers, plasticizers, antioxidants, antibacterial agents, and colorants.

The pH of the aqueous surface treatment agent according to the present invention is preferably from 2 to 12, and more preferably from 3 to 10. When the pH of the aqueous surface treatment agent according to the present invention is from 2 to 12, the storage stability of the aqueous surface treatment agent is improved.

The aqueous surface treatment agent of the present embodiment may further contain an acid or a base as necessary to adjust the pH. The acid is not particularly limited, but examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, and hydrofluoric acid; and organic acids such as acetic acid, trifluoroacetic acid, and benzoic acid. The base is not particularly limited, but examples thereof include inorganic bases such as ammonia, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium hydrogen carbonate; and organic bases such as trimethylamine, diethylamine, and triethylamine.

The aqueous surface treatment agent according to the present invention may further contain an organic solvent miscible with water, if necessary, in order to adjust the solid content concentration and drying speed. Examples of organic solvents miscible with water include, but are not 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.

- Manufacturing method of the aqueous surface treatment agent [0113] The manufacturing method of the aqueous surface treatment agent according to the present invention is not particularly limited, and the aqueous surface treatment agent can be manufactured by a known method, for example, by mixing the above-mentioned components (A) to (C) and, if necessary, other components in water as a solvent and stirring the mixture.

Surface-treated metal The aqueous surface treatment agent according to the present invention can be used to form a surface-treated metal. The surface-treated metal according to the present invention has a coating formed by surface-treating a metal with the aqueous surface treatment agent described above.

Metals The metals are not particularly limited, but include, for example, iron, zinc, aluminum, copper, nickel, etc., 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, etc. Among these, from the viewpoints of electrical conductivity, processability, and adhesion, aluminum or aluminum alloys, iron or iron alloys, or copper or copper alloys are preferred, aluminum or aluminum alloys, or copper or copper alloys are more preferred, and aluminum or aluminum alloys are even 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, aluminum die-cast (ADC material), etc. When the surface-treated metal according to the present invention is used as a battery exterior material for a secondary battery (particularly, a laminated battery such as a laminated lithium-ion secondary battery) or a positive electrode tab lead, it is preferable to use an A1050 material, an A1N30 material, an A8021 material, an A8079 material, or the like as the aluminum alloy. Examples of the iron alloy include cold-rolled steel plates such as SPCC, SPCD, and SPCE, and stainless steel (SUS). Examples of the 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 the zinc alloy include Zn-Al alloys. Examples of the copper alloy include brass. Examples of the nickel alloy include Ni-P alloys.

The shape of the metal is not particularly limited, but examples include foil or plate shapes. When using a foil or plate-shaped metal, only one side may be surface-treated with an aqueous surface treatment agent, or both sides may be surface-treated with an aqueous surface treatment agent. When both sides are surface-treated, both sides may be surface-treated with a single aqueous surface treatment agent, or each side may be surface-treated with an aqueous surface treatment agent of a different composition.

The metal 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 the plating method include electroplating, electroless plating, hot-dip plating, vacuum deposition, sputtering, and ion plating. When the surface-treated metal according to the present invention is used as a negative electrode tab lead, it is desirable to use nickel-plated copper or the like as the plated metal.

The surface-treated metal according to the present invention may be a metal having a coating that has been laminated. That is, a laminate film may be adhered to the metal having a coating. When a foil-like or plate-like metal having a coating is used, the laminate film may be adhered to only one side, or may be adhered to both sides. When a laminate film is adhered to both sides, the same type of laminate film may be adhered to both sides, or a different type of laminate film may be adhered to each side.

Materials constituting the laminate film and the insulating seal are not particularly limited, but examples thereof include polyethylene resins, polypropylene resins, polycarbonate resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyvinylidene chloride resins, polyvinyl acetate resins, polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene terephthalate resins, polyethylene isophthalate resins, copolymer polyester resins, polyester resins, polyamide resins, polyimide resins, polyetherimide resins, polyphenylene sulfide resins, fluorine resins, silicone resins, nylon resins, phenol resins, (meth)acrylic resins, epoxy resins, polymetaxylylene azibamide resins, etc. These materials may be used alone or in combination of two or more.

The laminate film and insulating seal may be uniaxially or biaxially stretched.

The laminate film and insulating seal may be a single layer film or a multilayer film in which multiple (types) of films are laminated. When multiple films are laminated, each film may be laminated via an adhesive, or directly without an adhesive. The adhesive may be a one-component curing adhesive or a two-component curing adhesive. Examples of the 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. Examples of methods for directly laminating multiple films without an adhesive include methods of bonding in a hot-melt state, such as co-extrusion, sand lamination, and thermal lamination.

The surface-treated metal according to the present invention may have a laminate film or an insulating seal bonded thereto by heat compression. When a laminate film or an insulating seal is bonded to the surface-treated metal by heat compression, a polyolefin resin is preferable as the material of the surface of the laminate film or insulating seal that comes into contact with the surface-treated metal. Examples of polyolefin resins include polyolefin resins such as low-density, medium-density, and high-density polyethylene, polypropylene, and polybutene, and acid-modified polyolefin resins obtained by graft-modifying these polyolefin resins with maleic anhydride or the like. These polyolefin resins may be used alone or in combination of two or more types. Among these, acid-modified polyolefin resins obtained by graft-modifying polyolefin resins with maleic anhydride or the like are preferable.

The laminate film and insulating seal may be a single layer film made of a polyolefin resin such as an acid-modified polyolefin resin, or may be a polyolefin resin such as an acid-modified polyolefin resin laminated with a heat-resistant resin such as polyethylene terephthalate or polyethylene naphthalate.

The surface-treated metal according to the present invention may have layers (other layers) other than the coating, the laminate film, and the insulating seal. The other layers may be placed between the coating and the laminate film, or between the coating and the insulating seal, or may be placed on the laminate film or the insulating seal. Also, the other layers may be placed on the coating without using the laminate film or the insulating seal.

The other layers are not particularly limited, but examples 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 printing layer, a polarizing plate, a colored layer, a liquid crystal layer, a light guide plate, a transparent conductive film, and a spacer. The other layers may be used alone or in combination of two or more.

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

Examples of resin components 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, and fluorinated ethylene-propylene copolymer resins. These resin components may be used alone or in combination of two or more. Examples of combinations of two or more adhesives 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, and polyester resins and metal-modified polyolefin resins.

Polyolefin resins used as resin components constituting the adhesive that can be used to form the adhesive layer include acid-modified polyolefin resins and metal-modified polyolefin resins. Examples of acid-modified polyolefin resins include polyolefin resins that are acid-modified with unsaturated carboxylic acids such as maleic anhydride-modified polypropylene or their anhydrides. 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-2 00PM, A-201PM, H-100, H-200, XP01A, XP01B/11B, XP03F, XP04A, etc.), Mitsubishi Chemical's Modic (P502, P512VB, P553A, P674V, P565, P555, P908H511, H503, H514, L502, L504, M142, M512, M522, M545, A543, F502, F573, F534A, etc.), Unitika's Arrowbase (SB-1200, SE-1200, SD-1200, DA1010, DC-1010, YA-6010, etc.), etc.

The method for forming the adhesive layer is not particularly limited, but examples include the extrusion molding method and the dispersion method.

Surface Treatment The surface treatment method includes a film formation step of forming a film by treating the surface of a metal with the aqueous surface treatment agent according to the present invention.

The film formation process involves, for example, applying the aqueous surface treatment agent of the present invention to the metal surface and then drying it.

Methods for applying the aqueous surface treatment agent according to the present invention are not particularly limited, but examples 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.

The drying method is not particularly limited, but any known method can be used, such as a heating and drying method using an oven, a drying method using forced circulation of hot air, or a drying method using an electromagnetic induction heating furnace using an IH heater or the like. The heating and 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 heating and drying can be set as desired.

In the film formation process, the aqueous surface treatment agent according to the present invention may be applied to the metal surface while drying. For example, the aqueous surface treatment agent according to the present invention may be applied to a preheated metal surface and then dried.

The amount of the coating formed after drying in the coating formation step is preferably 0.1 mg/m ² or more and 5000 mg/m ² or less, and more preferably 10 mg/m ² or more and 1000 mg/m ² or less.

The surface treatment method may further include a lamination process in which the metal having the coating is laminated.

The method for laminating the metal having the coating is not particularly limited, but known methods such as dry lamination, wet lamination, heat lamination, and extrusion lamination can be used.

The present invention will be described in more detail below with reference to examples. However, these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

The materials of the aqueous surface treatment agent used in the examples are as follows:

Component A: Cerium compound material Component A1: Cerium oxide sol (manufactured by Taki Chemical Industry, product name "Needral B-10", _CeO2 content 10%, particle size D ₅₀ 8 nm, dispersant: organic acid, pH 8)
Component A2: Cerium oxide sol (manufactured by Taki Chemical Industry, product name "Needral P-10", _CeO2 content 10%, particle size D ₅₀ 8 nm, dispersant: phosphoric acid-based, pH 7)
Component A3: Cerium oxide sol (manufactured by Daiichi Kigenso Kagaku, product name "CESL-30N", concentration 30.0 to 31.0 wt%, specific gravity 1.35 to 1.45, particle size D ₅₀ 5 to 15 nm, solvent: water, pH 2.0 to 3.0)
Component A4: Cerium(III) chloride
Component A5: Ammonium cerium nitrate (IV)
Components A1 to A3 correspond to the cerium oxide sol (A).

Component B: Phosphorus compound Component B1: Hydroxyethylidene diphosphonic acid (HEDP, manufactured by Chelest, number of phosphonic acid groups/phosphate groups: 2)
Component B2: 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC, manufactured by Chelest, number of phosphonic acid groups/phosphate groups: 1)
Component B3: Nitrilotris(methylenephosphonic acid) (NTMP, manufactured by Chelest, number of phosphonic acid groups/phosphate groups: 3)
Component B4: Ethylenediaminetetramethylenephosphonic acid (EDTMP, manufactured by Chelest, number of phosphonic acid groups/phosphate groups: 4)
Component B5: Phytic acid (number of phosphonic acid groups/phosphate groups: 6)
Component B6: phosphoric acid Component B7: sodium tripolyphosphate Component B8: potassium tripolyphosphate Components B1 to B5 correspond to the organophosphorus compound (B) having a phosphonic acid group and/or a phosphate group.

Component C: Oxazoline group-containing resin (C)
Component C1: oxazoline group-containing water-soluble polymer (manufactured by Nippon Shokubai, product name "Epocross WS-300", polymer main chain: acrylic, oxazoline equivalent (WPO) 130 g solid/equivalent (theoretical value), oxazoline group amount 7.7 mmol/g solid (theoretical value), glass transition temperature Tg: 90°C (calculated value), number average molecular weight Mn: 4 x 10 ⁴ , weight average molecular weight Mw: 12 x 10 ⁴ , non-volatile content 10 wt%, solvent: water, pH 7 to 10)
Component C2: oxazoline group-containing water-soluble polymer (manufactured by Nippon Shokubai, product name "Epocross WS-500", polymer main chain: acrylic, oxazoline equivalent (WPO) 220 g solid/equivalent (theoretical value), oxazoline group amount 4.5 mmol/g solid (theoretical value), glass transition temperature Tg: 50°C (actual value), number average molecular weight Mn: 2 x 10 ⁴ , weight average molecular weight Mw: 7 x 10 ⁴ , non-volatile content 39 wt%, solvent: water/1-methoxy-2-propanol, pH 8 to 10)
Component C3: oxazoline group-containing water-soluble polymer (manufactured by Nippon Shokubai, product name "Epocross WS-700", polymer main chain: acrylic, oxazoline equivalent (WPO) 220 g solid/equivalent (theoretical value), oxazoline group amount 4.5 mmol/g solid (theoretical value), glass transition temperature Tg: 50°C (actual value), number average molecular weight Mn: 2 x 10 ⁴ , weight average molecular weight Mw: 4 x 10 ⁴ , non-volatile content 25 wt%, solvent: water, pH 7 to 10)

Component D: Other resins (D)
Component D1: Ammonium polyacrylate (manufactured by Toa Gosei, product name "Aron A-30SL")
Component D2: Aminated phenolic resin (manufactured by Maruzen Petrochemicals, product name "Marukalinker MAM")
Component D3: Carbonyl group-containing polyvinyl alcohol (manufactured by Vinyl Acetate-Poval, product name "DF-17")
Component D4: Polyallylamine (manufactured by Nittobo Medical Co., Ltd., product name "PAA-15C")

Examples 1 to 27 and Comparative Examples 1 to 11
Preparation of Aqueous Surface Treatment Agent Each component was mixed with water in the proportions shown in Table 1 to prepare an aqueous surface treatment agent.

・Creating and evaluating evaluation samples ・Primary rust prevention treatment (film formation)
<Positive electrode tab lead and negative electrode tab lead>
The metal plate was surface-treated with the aqueous surface treatment agent prepared above to form a film. As a specific procedure for the surface treatment, the metal plate (metal terminal) was first degreased at 65°C for 3 seconds using a 1% by mass diluted solution of Surf Cleaner EC374 (manufactured by Nippon Paint Surf Chemicals). Next, the aqueous surface treatment agent prepared above was applied by gravure coating and dried at 200°C for 30 seconds to form a surface treatment film. As the metal terminal, an aluminum plate (A1050 material) having a width of 20 mm, a length of 50 mm, and a thickness of 0.4 mm was used as the positive electrode tab lead, and a Ni-plated Cu plate having a width of 20 mm, a length of 50 mm, and a thickness of 0.4 mm was used as the negative electrode tab lead. Next, the metal terminal on which the surface treatment film was formed was sandwiched between a pair of resin films. This was placed between heat seal bars, and the metal terminal on which the surface treatment film was formed and the resin film were pressurized and heat-welded to produce an electrode terminal. The resin film used was a single-layer film (width 10 mm, length 40 mm, thickness 80 μm) of maleic anhydride-modified polyolefin resin obtained by graft-modifying maleic anhydride to polyolefin resin. The conditions for pressurized heat welding were a gap between the heat seal bars of 210 μm, a temperature of 200° C., and a thrust of the heat seal bars of 400 N.

<Laminate material>
A 40 μm thick Al foil (A8021 material) was degreased with a 1% by mass diluted solution of Surf Cleaner EC374 (manufactured by Nippon Paint Surf Chemicals) at 65° C. for 3 seconds. Next, the aqueous surface treatment agent prepared above was applied using a bar coater (#6), and then the foil was dried in a hot air oven at a material temperature of 190° C. or higher for 2 minutes to form a surface treatment film.
Subsequently, the metal plate on which the film was formed was laminated. Specifically, a maleic anhydride-modified polypropylene dispersion as an adhesive was applied to the film formed on the surface of the metal plate so that the amount of application when dried was 3 g/ ^m2 , and then dried to form an adhesive layer. Next, a polypropylene film was heated and pressed onto the metal plate on which the adhesive layer was formed under conditions of 190°C and 0.38 MPa. The laminated Al foil was cut into a size of 150 mm x 15 mm.

Initial Adhesion Using a bench-top precision universal testing machine Autograph AGS-5KNX (manufactured by Shimadzu Corporation), the peel strength was measured when peeling the polypropylene film from the Al foil of a laminated Al foil test piece at a peel speed of 50 mm/min and an angle of 180 degrees, and this value was taken as the "initial peel strength." In addition, in the case of a positive electrode tab lead or a negative electrode tab lead, the peel strength was measured when peeling the maleic anhydride-modified polyolefin resin film from the metal terminal in a similar manner, and this value was taken as the "initial peel strength."

Evaluation of electrolyte resistance 1000 ppm of ion-exchanged water was added to an electrolyte LBG-00015 (Kishida Chemical Co., Ltd.) in which _{1M LiPF6} was dissolved in a mixed solvent of ethylene carbonate/dimethyl carbonate/diethyl carbonate (volume ratio 1/1/1) to obtain a test electrolyte.

After immersing the test piece in the test electrolyte at 85°C for 14 days, the peel strength was measured and electrolyte resistance was evaluated in the same manner as above. This value was taken as the "peel strength after immersion in electrolyte."

The ratio of the "peel strength after immersion in electrolyte" to the "initial peel strength" was taken as the peel strength retention rate, which was used as an index of electrolyte resistance. The higher the peel strength retention rate, the higher (better) the electrolyte resistance can be evaluated. The electrolyte resistance of the positive electrode tab lead, the negative electrode tab lead, and the laminated Al foil was evaluated according to the following evaluation criteria.
5: Peel strength maintenance rate is 80% or more 4: Peel strength maintenance rate is 60% or more and less than 80% 3: Peel strength maintenance rate is 40% or more and less than 60% 2: Peel strength maintenance rate is 20% or more and less than 40% 1: Peel strength maintenance rate is less than 20% or peeling

The evaluation results are shown in Table 2.

From Table 2, it can be seen that when the metal plate is surface-treated with the aqueous surface treatment agents of Examples 1 to 27, the electrolyte resistance of the positive electrode tab lead, negative electrode tab lead, and laminate material is high.

In contrast, the aqueous surface treatment agents of Comparative Examples 1 to 3 do not contain an oxazoline group-containing resin (C), an organic phosphorus compound having a phosphonic acid group and/or a phosphoric acid group (B), or cerium oxide sol (A), and therefore the electrolyte resistance of the positive electrode tab lead, negative electrode tab lead, and laminate material is low. The aqueous surface treatment agents of Comparative Examples 4 and 5 use a water-soluble cerium compound as the cerium compound material, and therefore the electrolyte resistance of the positive electrode tab lead, negative electrode tab lead, and laminate material is low. The aqueous surface treatment agents of Comparative Examples 6 to 9 use an inorganic phosphorus compound or its salt as the phosphorus compound, and therefore the electrolyte resistance of the positive electrode tab lead, negative electrode tab lead, and laminate material is low. The aqueous surface treatment agent of Comparative Example 10 uses ammonium polyacrylate as the resin component, but does not contain an oxazoline group-containing resin (C), and therefore the electrolyte resistance of the positive electrode tab lead, negative electrode tab lead, and laminate material is low. The aqueous surface treatment agent of Comparative Example 11 cannot be used to treat metal surfaces because a precipitate immediately occurs when cerium oxide sol and polyallylamine are mixed.

According to the present invention, it is possible to provide an aqueous surface treatment agent which, when used in the surface treatment of a metal, can improve the adhesion between the metal and the laminate film after lamination processing and the electrolyte resistance when the metal is used as a tab lead for a secondary battery.

Claims (11)

An aqueous surface treatment agent for use in surface treatment of metals, comprising:
A cerium oxide sol (A),
an organophosphorus compound (B) having a phosphonic acid group and/or a phosphoric acid group;
an oxazoline group-containing resin (C);
An aqueous surface treatment agent comprising: The aqueous surface treatment agent according to claim 1, wherein 50% or more of the solid mass of the resin component of the aqueous surface treatment agent is the oxazoline group-containing resin (C). The aqueous surface treatment agent according to claim 1, wherein the organophosphoric compound (B) having a phosphonic acid group and/or a phosphate group has a total of two or more phosphonic acid groups and/or phosphate groups in one molecule. The aqueous surface treatment agent according to claim 3, wherein the organophosphorus compound (B) having a phosphonic acid group and/or a phosphate group is phytic acid or a salt thereof. A surface-treated metal having a coating formed by surface-treating the metal with the aqueous surface treatment agent according to any one of claims 1 to 4. The surface-treated metal according to claim 5, wherein the metal is aluminum or an aluminum alloy, or copper or a copper alloy. The surface-treated metal according to claim 5, wherein the metal is plated. The surface-treated metal according to claim 5, which has a polyolefin-based resin film layer on the coating of the metal having the coating. The surface-treated metal according to claim 8, which is a tab lead for a secondary battery. The surface-treated metal according to claim 5, wherein the metal having the coating is laminated. The surface-treated metal according to claim 10, which is an exterior material for a battery.