Surface treatment agent for copper-based metal material, method for producing copper-based metal material with coating film, and method for

Abstract

The invention discloses a surface treatment agent for a copper-based metal material, a method for manufacturing a copper-based metal material with a coating film, and a method for preventing corrosion of the copper-based metal material. The copper metal material is subjected to surface treatment by using the surface treatment agent containing the compound with the tetrazole skeleton, the polymer containing the allylamine or the chemically modified allylamine as the constituent unit, and the compound with the phosphonic acid group, so that the anti-oxidation performance of the copper foil can be improved while environmental protection is realized, and the service life of the copper foil is prolonged. The problems in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to a surface treatment agent for copper-based metal materials, a method for manufacturing copper-based metal materials with a coating, and a method for preventing corrosion of copper-based metal materials. Background Technology

[0002] In traditional copper foil technology, an anti-oxidation layer is formed on the surface of the copper foil to prevent oxidation. This anti-oxidation layer allows for long-term preservation in atmospheric conditions and inhibits oxidation during processing and use at high temperatures.

[0003] One method for forming an anti-oxidation layer on the surface of copper foil is by electrolysis to form a nickel (Ni) plating, a zinc (Zn) plating, or a nickel-zinc (Ni-Zn) alloy plating.

[0004] However, when the above-mentioned coatings are used as anti-oxidation layers for copper foils for lithium-ion batteries, the nickel or zinc contained in the coatings may impair the function and stability of the lithium-ion batteries. Therefore, there are usually limitations to using these coatings as anti-oxidation layers for copper foils for lithium-ion batteries.

[0005] As a method for forming an anti-oxidation layer on copper foil for lithium-ion batteries, there is a known method of electrolytic treatment using agents containing hexavalent chromium. However, from an environmental protection point of view, it is required to use chromium-free agents that do not contain hexavalent chromium for surface treatment.

[0006] For example, Patent Document 1 discloses a technique for surface-treated copper foil treated with a solution containing triazole compounds and carboxylic anhydrides.

[0007] Existing technical documents: Patent documents: Patent document 1: WO2014 / 017449A. Summary of the Invention

[0008] (a) Technical problems to be solved As mentioned above, while considering environmental protection, it is also necessary to further improve the anti-oxidation performance of copper foil.

[0009] The purpose of this invention is to provide a chromium-free surface treatment agent for copper-based metal materials, a method for manufacturing copper-based metal materials with a film using the surface treatment agent, and a method for preventing corrosion of copper-based metal materials.

[0010] (II) Technical Solution The inventors of this invention conducted in-depth research to solve the above-mentioned technical problems and found that the above-mentioned problems could be solved by using a surface treatment agent containing a compound with a tetrazolium skeleton, a polymer containing allylamine or chemically modified allylamine as a constituent unit, and a compound with a phosphonic acid group to perform surface treatment on copper-based metal materials, thereby completing this invention.

[0011] That is, the present invention relates to the following: Option 1: The surface treatment agent for copper-based metal materials for cathode electrolysis of the present invention contains a compound (A) having a tetrazolium skeleton, a polymer (B) containing allylamine or chemically modified allylamine as a constituent unit, a compound (C) having a phosphonic acid group, and water.

[0012] According to the copper-based metal surface treatment agent, the concentration of the polymer (B) containing allylamine or chemically modified allylamine as a constituent unit is 250 ppm or more.

[0013] According to the surface treatment agent for copper-based metal materials, the concentration of the compound (C) having a phosphonic acid group is 250 ppm or more.

[0014] According to the surface treatment agent for copper-based metal materials, the concentration of the compound (A) having a tetrazolium framework is 250 ppm or more.

[0015] Option 2: The method for manufacturing a copper-based metal material with a coating according to the present invention includes a step of contacting a copper-based metal material with the copper-based metal material of the present invention using a surface treatment agent and performing cathodic electrolysis treatment.

[0016] Option 3: The corrosion prevention method for copper-based metal materials of the present invention involves contacting the copper-based metal material with the copper-based metal material of the present invention using a surface treatment agent and then subjecting it to cathodic electrolysis treatment.

[0017] (III) Beneficial Effects According to the present invention, a surface treatment agent is provided that can form a film with excellent anti-oxidation properties on the surface of copper-based metal materials.

[0018] Furthermore, a method for manufacturing copper-based metal materials having a film with excellent anti-oxidation properties on the surface using the surface treatment agent can be provided. Moreover, a method for preventing corrosion of copper-based metal materials using the surface treatment agent can be provided. Detailed Implementation

[0019] The present invention will now be described in detail through specific embodiments. It should be noted that the numerical range indicated by “~” in the present invention refers to the range including the values ​​recorded before and after “~” as both the lower and upper limits.

[0020] Surface treatment agents for copper-based metals The surface treatment agent for copper-based metal materials of this embodiment contains a compound (A) having a tetrazolium skeleton, a polymer (B) containing allylamine or chemically modified allylamine as a constituent unit, a compound (C) having a phosphonic acid group, and water.

[0021] <Compounds with a tetrazolium skeleton (A)> The surface treatment agent for copper-based metal materials contains compound (A) with a tetrazolium framework (hereinafter also referred to as "compound (A)").

[0022] Compound (A) is an organic compound whose chemical structure contains a tetrazolium skeleton, but preferably a single organic compound that does not contain repeating structures.

[0023] The molecular weight of compound (A) is not particularly limited as long as it can achieve the desired performance; it can be less than 500, less than 300, and preferably less than 200.

[0024] Compound (A) may or may not have functional groups on the tetrazolium skeleton.

[0025] Compound (A) can be in free form or in the form of a salt.

[0026] Examples of compound (A) include, but are not limited to, 1H-tetrazole, 5-amino-1H-tetrazole, 1-methyl-1H-tetrazole-5-amine, 2-methyl-2H-tetrazole-5-amine, etc. In surface treatment agents for copper-based metal materials, compound (A) may be used in combination with only one compound or with two or more compounds.

[0027] From the viewpoint of the antioxidant properties of copper-based metal materials, the concentration of compound (A) in the surface treatment agent is preferably 100 ppm or more, more preferably 250 ppm or more, further preferably 500 ppm or more, and even more preferably 750 ppm or more. Furthermore, there is no particular upper limit to the concentration, but when it exceeds 1500 ppm, the antioxidant effect tends to saturate relative to the amount used. For economic reasons, it can be 5000 ppm or less, 2000 ppm or less, or 1500 ppm or less. Therefore, the concentration of compound (A) in the surface treatment agent for copper-based metal materials is preferably in the range of 100 to 5000 ppm, more preferably in the range of 250 to 2000 ppm, and even more preferably in the range of 750 ppm to 500 ppm. Furthermore, when the surface treatment agent for copper-based metal materials contains two or more compounds (A), the above concentration refers to their combined value.

[0028] <Polymers containing allylamine or chemically modified allylamine as constituent units (B)> The surface treatment agent for copper-based metal materials contains a polymer (B) (hereinafter also referred to as "polymer (B)") that comprises allylamine or chemically modified allylamine as a constituent unit.

[0029] There are no particular restrictions on polymer (B) as long as it contains allylamine or chemically modified allylamine as a constituent unit. That is, polymer (B) can be a homopolymer of allylamine, a homopolymer of chemically modified allylamine, a copolymer of allylamine and chemically modified allylamine, or a copolymer containing allylamine or chemically modified allylamine and other constituent units.

[0030] Homopolymers of allylamine include polyallylamine.

[0031] Copolymers of allylamine and chemically modified allylamine can include partially methoxycarbonylated allylamine polymers, partially methylcarbonylated allylamine polymers, partially ureated polyallylamine polymers, and partially carboxymethylated polyallylamine polymers.

[0032] Copolymers containing allylamine or chemically modified allylamine with other constituent units include allylamine-diallylamine polymers, allylamine-diallyldimethylammonium chloride polymers, etc. Polymer (B) can also be in the form of a salt.

[0033] In surface treatment agents for copper-based metal materials, polymer (B) can be used in combination with only one type or with two or more types.

[0034] The molecular weight of polymer (B) is not particularly limited, but the weight-average molecular weight is preferably in the range of 500 to 200,000, more preferably in the range of 800 to 100,000, and even more preferably in the range of 800 to 10,000. Furthermore, the weight-average molecular weight is determined by GPC (gel permeation column chromatography) and converted to polystyrene.

[0035] The concentration of polymer (B) in the surface treatment agent for copper-based metal materials is preferably 100 ppm or more, more preferably 250 ppm or more, and even more preferably 500 ppm or more. Furthermore, there is no particular upper limit to the concentration, but when the concentration of polymer (B) exceeds 1500 ppm, the improvement in antioxidant properties relative to the amount used tends to saturate. Therefore, the concentration of polymer (B) can be 5000 ppm or less, 2000 ppm or less, or 1500 ppm or less. That is, the concentration of polymer (B) in the surface treatment agent for copper-based metal materials is preferably in the range of 100 to 5000 ppm, more preferably in the range of 250 to 1500 ppm, and even more preferably in the range of 500 to 1500 ppm. Moreover, when the surface treatment agent for copper-based metal materials contains two or more polymers (B), the above concentration refers to their combined value.

[0036] <Compounds with phosphonic acid groups (C)> The surface treatment agent for copper-based metal materials contains a compound (C) having a phosphonic acid group. The compound (C) having a phosphonic acid group can be an organic compound or an inorganic compound, but an inorganic compound is preferred.

[0037] Organic compounds containing phosphonic acid groups include, but are not limited to, hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, phosphonobutane tricarboxylic acid, and ethylenediaminetetramethylenephosphonic acid. In addition, inorganic compounds containing phosphonic acid groups include, but are not limited to, phosphoric acid and tripolyphosphates.

[0038] The compound (C) containing a phosphonic acid group can be in free form or in the form of an alkali metal salt, but the free form is preferred. Substances commonly used as anionic surfactants (e.g., alkylphosphonic acids) are excluded from the compound (C) containing a phosphonic acid group. In surface treatment agents for copper-based metal materials, only one compound (C) containing a phosphonic acid group may be used, or two or more compounds may be used.

[0039] The concentration of the phosphonic acid-containing compound (C) in the surface treatment agent for copper-based metal materials is preferably in the range of 100 to 5000 ppm, more preferably in the range of 250 to 2000 ppm, and even more preferably in the range of 500 to 1500 ppm. When the concentration of the phosphonic acid-containing compound (C) is within this range, the copper-based metal materials exhibit excellent oxidation resistance. Furthermore, when the surface treatment agent for copper-based metal materials contains two or more phosphonic acid-containing compounds (C), the above concentration refers to their combined value.

[0040] <Media> Surface treatment agents for copper-based metal materials contain water or a mixture of water and water-miscible solvents, used to dissolve or disperse the various components. From the viewpoint of ease of handling the surface treatment agent, water is preferred as the medium, and deionized water is more preferred.

[0041] The water content, relative to the total amount of surface treatment agent, is preferably 80 to 99.95% by mass, more preferably 85 to 99.9% by mass.

[0042] When using a mixture of water and a water-miscible solvent, the proportion of water is preferably, for example, 60% by mass or more of the total mass of the mixed solvent. There are no particular limitations on the water-miscible solvent, as long as it is a substance that does not undergo phase separation when mixed with water; examples include alcohols such as methanol and ethanol.

[0043] <pH of surface treatment agents for copper-based metals> The pH of the surface treatment agent for copper-based metal materials is preferably in the acidic to neutral range, more preferably in the weakly acidic to neutral range. Specifically, the pH value is preferably in the range of 1 to 7, more preferably in the range of 2.5 to 5.4, further preferably in the range of 3 to 5, and particularly preferably in the range of 3.5 to 5. Furthermore, the pH can be measured at 25°C using a commercially available pH meter.

[0044] Surface treatment agents for copper-based metals can contain various additives as needed. Examples of additives include surfactants, defoamers, and pH adjusters, but are not limited to these.

[0045] Method for manufacturing surface treatment agents for copper-based metal materials The aforementioned surface treatment agent for copper-based metal materials can be manufactured by using at least a compound (A) having a tetrazolium skeleton, a polymer (B) containing allylamine or chemically modified allylamine as constituent units, and a compound (C) having a phosphonic acid group as raw materials, in a medium containing water in a specified amount.

[0046] Surface treatment methods for copper-based metals The surface treatment method for copper-based metal materials using this copper-based metal material surface treatment agent involves contacting the copper-based metal material with the copper-based metal material surface treatment agent and performing cathodic electrolysis treatment.

[0047] Therefore, a film with excellent anti-oxidation properties can be formed on the surface of copper-based metal materials. That is, the manufacturing method of copper-based metal materials with film includes a step of contacting copper-based metal materials with a surface treatment agent and performing cathodic electrolysis treatment (hereinafter also referred to as "cathodic electrolysis treatment step").

[0048] <Cathode Electrolysis Process> The cathodic electrolysis process involves contacting a copper-based metal material with a copper-based metal surface treatment agent, using the copper-based metal material as the cathode and the counter electrode material as the anode, and connecting it to an external power source to apply voltage. The counter electrode material is typically made of a material that does not dissolve or corrode within the treatment potential range. Examples of preferred materials include platinum titanium electrodes plated with platinum, and DSE electrodes plated with ruthenium oxide on titanium, but these are not limited to these.

[0049] There are no particular restrictions on the electrolysis density in the cathode electrolysis process, but it is usually between 0.01 and 10 A / dm³. 2 Within the range of 0.02 to 5 A / dm, it is preferred. 2 More preferably, it is within the range of 0.05 to 1 A / dm. 2 Within the range.

[0050] There is no particular limitation on the electrolysis time in the cathode electrolysis process, but it is preferably in the range of 1 second to 60 seconds. In addition, the contact temperature in the cathode electrolysis process is usually in the range of 10°C to 50°C.

[0051] In addition, a pretreatment process can be performed before the cathode electrolysis process. Examples of pretreatment processes include pickling and degreasing. These pretreatment processes can be performed as a single process or in combination of two or more processes performed sequentially.

[0052] In addition, post-processing steps can be performed after the cathode electrolysis process. Examples of post-processing steps include washing and drying. These post-processing steps can be performed as a single step or in combination of two or more steps performed sequentially.

[0053] <Copper-based metal materials> Examples of copper-based metal materials include, in addition to materials composed of a single material such as copper or copper alloys, metal materials and resin materials that have been coated or vapor-deposited with copper or copper alloys.

[0054] There are no particular restrictions on the shape of metallic materials; they can be in the form of plates or foils. Foil-shaped materials can be manufactured by electrolysis or rolling, but there are no particular restrictions.

[0055] <Copper-based metal materials with coating> The copper-based metal material with a coating is obtained by contacting the copper-based metal material with the aforementioned surface treatment agent and performing a cathodic electrolysis process.

[0056] The film formed by surface treatment of copper-based metal materials preferably has a mass per unit area of ​​1 mg / m³. 2 The above, more preferably 5 mg / m 2 That's all. Additionally, there is no specific upper limit, but 500 mg / m³ is preferred. 2 The following is more preferably 100 mg / m 2 the following.

[0057] Copper-based metal materials with coatings are suitable for current collectors in lithium-ion batteries because oxidation is suppressed.

[0058] Example The effects of the present invention will be described in detail below through examples, but the scope of the present invention is not limited to the following examples.

[0059] Metallic materials Prepare electrolytic copper foil with a length of 150 mm and a width of 70 mm, and the thickness of the electrolytic copper foil is 5 μm, as the material to be processed.

[0060] Preparation of surface treatment agents The surface treatment agents of Examples 1-30 and Comparative Examples 2-12 were prepared by using the organic compounds, polymers, and compounds with phosphonic acid groups shown below, making their components reach the concentrations shown in Table 1, and then adjusting the pH with sodium hydroxide or nitric acid.

[0061] <Organic Compounds> a1: 5-Amino-1H-tetrazole; a2: 1H-tetrazole; a3: 1,2,3-benzotriazole.

[0062] <Polymer> b1: Polyallylamine (weight average molecular weight 1500, solids concentration 15%) b2: Polyallylamine (weight average molecular weight 3000, solids concentration 20%) b3: Partially carboxymethylated polyallylamine (15% solids concentration); b4: Partially ureated polyallylamine polymer (weight average molecular weight 15000, solids concentration 15%). b5: Polyethyleneimine (weight average molecular weight 800, solids concentration 90%); b6: Polydiallylamine (solids concentration 25.5%); b7: Polyurethane (solids concentration 26%).

[0063] <Compounds with phosphonic acid groups> c1: Phosphoric acid; c2: Sodium phosphate; c3: Aminotrimethylenephosphonic acid.

[0064] Production of copper foil with film The electrolytic copper foil was immersed in 5% sulfuric acid at 25°C for 30 seconds, followed by rinsing with water to clean the surface. Next, the cleaned electrolytic copper foil was immersed in the surface treatment agent at 25°C described in Examples 1-30 and Comparative Examples 2-11 in Table 1. Using the electrolytic copper foil as the sample electrode and a platinum electrode as the counter electrode, a current density of 0.25 A / dm³ was applied at an electrode distance of 4 cm. 2 Cathodic electrolysis was performed under specific conditions. Afterwards, the copper foil was washed with water and dried using a cold air dryer to produce a copper foil with a coating.

[0065] <Comparative Example 1> The above-mentioned electrolytic copper foil was immersed in 5% sulfuric acid at 25°C for 30 seconds, washed with water and dried with a cold air dryer to produce copper foil without a film.

[0066] <Comparative Example 12> Except for changing the contact conditions of the surface treatment agent to no voltage applied and immersion at 25°C for 5 seconds, the same treatment as in Example 1 was used to produce the copper foil with a film related to Comparative Example 12.

[0067] <Comparative Example 13> A copper foil with a film, as described in Example 1 of Patent Document 1, was produced using the surface treatment agent and without applying voltage, with the same contact conditions as in Example 1. Furthermore, the surface treatment agent described in Example 1 of Patent Document 1 was prepared by adding 55 ppm of 1,2,3-benzotriazole and 3 ppm of anhydrous propionic acid to water.

[0068] Table 1

[0069] The content of each compound in the examples and comparative examples in Table 1 is in ppm.

[0070] For the copper foils related to Examples 1-30 and Comparative Examples 1-13, the adhesion of carbon (C), nitrogen (N), and phosphorus (P) was determined by fluorescence X-ray analysis to determine whether a film had formed.

[0071] In Examples 1-30, Comparative Examples 5-6, and Comparative Examples 8-12, C, N, and P were all detected.

[0072] On the other hand, in Comparative Example 1, C, N, and P were not detected; in Comparative Examples 2, 3, and 7, P was not detected; and in Comparative Example 4, C and N were not detected.

[0073] <Color difference measurement after heating 1> The obtained copper foil with coating was heated at 150°C for 15 minutes under natural air conditions, and the color difference ΔE between the obtained foil and the original color was measured using a colorimeter (Konica Minolta, CM-2600d). The results are shown in Table 1. The obtained color difference ΔE was evaluated according to the following evaluation criteria. Rating 2 or above is considered good.

[0074] Evaluation Criteria Table

[0075] <Color Difference Measurement After Heating 2> The obtained copper foil with coating was heated at 150°C for 60 minutes under natural air conditions, and the color difference ΔE between the obtained foil and the initial color was measured using a colorimeter (Konica Minolta, CM-2600d). The results are shown in Table 1. The obtained color difference ΔE was evaluated according to the following evaluation criteria. Rating 2 or above is considered good.

[0076] Evaluation Criteria Table

[0077] As shown in Table 1, the copper foils with film obtained in Examples 1 to 30 showed less color difference before and after heat treatment compared with copper foils without film on the surface (Comparative Example 1) and copper foils with film obtained in Comparative Examples 2 to 13, thus confirming that they have excellent anti-oxidation properties.

[0078] According to the present invention, a surface treatment agent for copper-based metal materials, a method for manufacturing copper-based metal materials with a coating, and a method for preventing corrosion of copper-based metal materials are provided, and the resulting copper-based metal materials with a coating exhibit excellent oxidation resistance. The surface treatment agent for copper-based metal materials, the method for manufacturing copper-based metal materials with a coating, and the method for preventing corrosion of copper-based metal materials related to the present invention are suitable for use as current collectors in lithium-ion batteries.

[0079] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A surface treatment agent for copper-based metal materials, characterized in that, The compound contains a compound (A) with a tetrazolium skeleton, a polymer (B) containing allylamine or chemically modified allylamine as a building block, a compound (C) with a phosphonic acid group, and water.

2. The surface treatment agent for copper-based metal materials according to claim 1, characterized in that, The concentration of the polymer (B) containing allylamine or chemically modified allylamine as a constituent unit is 250 ppm or more.

3. The surface treatment agent for copper-based metal materials according to claim 1 or 2, characterized in that, The concentration of the compound (C) having a phosphonic acid group is 250 ppm or higher.

4. The surface treatment agent for copper-based metal materials according to claim 1, characterized in that, The concentration of the compound (A) having a tetrazolium skeleton is above 250 ppm.

5. A method for manufacturing a copper-based metal material with a coating, characterized in that, The process includes contacting a copper-based metal material with the copper-based metal material according to any one of claims 1-4 using a surface treatment agent and performing cathodic electrolysis treatment.

6. A method for preventing corrosion of copper-based metal materials, characterized in that, The copper-based metal material is contacted with a surface treatment agent and subjected to cathodic electrolysis treatment according to any one of claims 1-4.

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