Method for evaluating the state of adhesion of components of an electrodeposition bath

Abstract

The present application provides a method for easily evaluating the adhesion state of an electrodeposition liquid component on a substrate. One embodiment of the present application relates to a method for evaluating the adhesion state of an electrodeposition liquid component on a substrate, the method comprising: a material preparation step of preparing a fluorescent compound and a substrate; a fluorescent compound adhesion step of causing the fluorescent compound to adhere to the substrate; a baking and curing step of baking and curing the adhered substrate obtained in the fluorescent compound adhesion step; and an evaluation step of irradiating the baked and cured substrate obtained in the baking and curing step with excitation light of the fluorescent compound and observing fluorescence.

Description

Technical Field

[0001] This invention relates to a method for evaluating the adhesion state of components in an electrodeposition solution. Background Technology

[0002] Electrodeposition is a technique that involves bringing an electrodeposition solution into contact with a substrate (e.g., immersing the substrate in the electrodeposition solution) and applying an electric current between the substrate and the counter electrode, thereby causing the components of the electrodeposition solution to adhere to the substrate. For example, when the electrodeposition solution component is a coating, it is also called electrodeposition coating.

[0003] As a technique for determining the composition of electrodeposition solutions, for example, Patent Document 1 describes a method for determining the concentration of fluororesin in an electrodeposition coating in a coating tank. The method is characterized by taking a portion of the electrodeposition coating as a test sample from a coating tank composed of an electrodeposition coating containing fluororesin with chlorine atoms and other resins as resin components, coating it onto a metal test plate by an electrodeposition coating method, and determining the concentration of chlorine atoms in the obtained coating by a fluorescence X-ray analysis method.

[0004] Patent Document 2 describes an apparatus in which a continuous electrodeposition coating apparatus having an ultrafiltration filter composed of an inorganic compound as a concentration mechanism for the electrodeposition solution, a metal ion removal mechanism based on chelated fibers with cellulose as the parent material, and a drying, baking, and curing mechanism within the same system can be controlled by measuring the concentration of the electrodeposition solution in the electrodeposition tank using UV spectrophotometry and providing feedback.

[0005] Patent document 3 describes a method for quantitatively evaluating the surface condition of a non-ferrous metal. The method is a method for quantitatively evaluating the surface condition of an electrodeposited metal plate obtained by electrodepositing or electrolytically refining the non-ferrous metal from an electrolyte containing the non-ferrous metal. The method is characterized by taking a picture of the surface of the electrodeposited metal plate by a photographic mechanism, calculating the standard deviation σ of the brightness distribution of the obtained image by a computing mechanism, and evaluating the surface condition of the electrodeposited metal plate based on the value.

[0006] Patent Document 1: Japanese Patent Application Publication No. 7-197296

[0007] Patent Document 2: Japanese Patent Application Publication No. 2005-336559

[0008] Patent Document 3: Japanese Patent Application Publication No. 2013-181911 Summary of the Invention

[0009] In electrodeposition, areas where the electrodeposition solution is not substantially adhered may sometimes arise due to the shape and / or material of the substrate. For example, in the case of bonding a foamed material to a conductive material, the electrodeposition solution may not adhere uniformly to the gaps at the interface between the foam and the conductive material, created by foaming the foamed material. Thus, these areas without electrodeposition solution may rust due to exposure of the exposed substrate to the external environment (e.g., oxygen and moisture). Rust formation accelerates substrate degradation, thereby reducing the durability and / or reliability of the final product manufactured using the substrate. However, a convenient method for evaluating the adhesion of the electrodeposition solution to the substrate is not yet known.

[0010] Therefore, the object of the present invention is to provide a simple method for evaluating the adhesion state of electrodeposition solution components on a substrate.

[0011] The inventors have conducted various studies on methods for solving the aforementioned problems. They discovered that by applying an evaluation solution containing a fluorescent compound to a substrate and observing the fluorescence emitted by the fluorescent compound, the adhesion state of the electrodeposition solution components on the substrate can be easily evaluated using this fluorescence as an indicator. Based on this insight, the inventors have completed the present invention.

[0012] That is, the present invention includes the following methods and embodiments.

[0013] (Embodiment 1) A method for evaluating the adhesion state of electrodeposition solution components on a substrate, the method comprising:

[0014] Material preparation process: preparing fluorescent compounds and substrates;

[0015] The fluorescent compound adhesion process allows the fluorescent compound to adhere to the substrate;

[0016] The baking and curing process involves baking and curing the substrate that has been adhered to during the fluorescent compound adhesion process; and

[0017] The evaluation process involves irradiating the baked and cured substrate obtained in the baking and curing process with the excitation light of a fluorescent compound and observing the fluorescence.

[0018] (Embodiment 2) According to the method of Embodiment 1, the fluorescent compound is contained in the electrodeposition solution, and in the fluorescent compound attachment process, the fluorescent compound and the components of the electrodeposition solution are attached together to the substrate.

[0019] (Embodiment 3) According to the method of Embodiment 1, the fluorescent compound is contained in an evaluation solution different from the electrodeposition solution, and in the fluorescent compound attachment process, the fluorescent compound is attached to the substrate by contacting the substrate with the evaluation solution.

[0020] (Embodiment 4) The method according to any one of Embodiments 1 to 3, wherein the substrate comprises a foaming material.

[0021] (Embodiment 5) The method according to any one of Embodiments 1 to 4, wherein the fluorescent compound is anthracene.

[0022] Invention Effects

[0023] This invention provides a simple method for evaluating the adhesion state of electrodeposition solution components on a substrate. Attached Figure Description

[0024] exist Figure 1 The figures show photographs of substrates subjected to a bake-curing process in either a flat or tilted configuration for evaluation purposes. In the figures, A is a photograph of the flat configuration, and B is a photograph of the tilted configuration. In the figures, areas enclosed by solid lines represent areas where fluorescence was observed, and areas enclosed by dashed lines represent areas coated with foaming material. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail.

[0026] One aspect of the present invention relates to a method for evaluating the adhesion state of electrodeposition solution components on a substrate.

[0027] In various embodiments of the present invention, the electrodeposition solution component refers to the component dissolved or dispersed in the electrodeposition solution and adhered to the substrate by electrodeposition. For example, in the case of electrodeposition coating, the electrodeposition solution component is a paint component. Furthermore, the electrodeposition solution is a solution or dispersion containing the electrodeposition solution components exemplified above. The solvent of the electrodeposition solution is preferably water or one or more water-miscible organic solvents or mixtures thereof.

[0028] In various embodiments of the present invention, the substrate can be formed of any conductive material commonly used for electrodeposition in this technical field. Furthermore, the shape of the substrate is not particularly limited. In addition to the conductive material, the substrate may also contain a material composed of one or more resins. Examples of such resin materials include foamed materials composed of thermoplastic resins such as polyethylene, polystyrene, polypropylene, or polyurethane. The substrate prepared in this process, for example, has a conductive material and a foamed material bonded to the surface of the conductive material. In the case where the foamed material is bonded to the conductive material, sometimes the electrodeposition solution components do not adhere uniformly to the gaps at the interface between the foam and the conductive material created by foaming the foamed material. By implementing the method of this embodiment, even with such a substrate, the adhesion state of the electrodeposition solution components on the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound attached to the substrate as an indicator.

[0029] This method includes a material preparation process, a fluorescent compound application process, a baking and curing process, and an evaluation process. Each process is described in detail below.

[0030] [1: Material preparation process]

[0031] This process includes preparing fluorescent compounds and substrates.

[0032] In all embodiments of the present invention, the fluorescent compound is not particularly limited as long as it is a compound that can be dissolved or dispersed in the solvent used in the electrodeposition solution. The fluorescent compound is preferably anthracene, coumarin 1, coumarin 6, or fluorescein, and more preferably anthracene. By using the fluorescent compound exemplified above to carry out the method of this embodiment, the adhesion state of the electrodeposition solution components on the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound attached to the substrate as an indicator.

[0033] The fluorescent compound can be contained in the electrodeposition solution used in this method, or it can be contained in an evaluation solution different from the electrodeposition solution used in this method. In the latter embodiment, the solvent of the evaluation solution is preferably substantially the same as the solvent used in the electrodeposition solution. The adhesion behavior of this evaluation solution on the substrate is expected to be substantially the same as that of the electrodeposition solution. Therefore, regardless of the embodiment, by implementing the method of this method, the adhesion state of the electrodeposition solution components on the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound attached to the substrate as an indicator.

[0034] The concentration of the fluorescent compound in the electrodeposition solution or evaluation solution can be appropriately set by those skilled in the art based on the fluorescence intensity and solubility of the fluorescent compound, as well as the shape of the substrate. The concentration of the fluorescent compound is preferably in the range of 0.001 to 1% by mass, more preferably in the range of 0.01 to 0.1% by mass.

[0035] The fluorescent compound and substrate prepared in this process can be any material having the characteristics described above. Each material can be prepared by oneself to have the specified characteristics, or it can be a commercially available product.

[0036] [2: Fluorescent compound attachment process]

[0037] This process includes attaching fluorescent compounds to a substrate.

[0038] In embodiments where the fluorescent compound is contained in the electrodeposition solution, this process can be performed by adhering the fluorescent compound and the electrodeposition solution components together onto the substrate. In this embodiment, for example, it is preferable to immerse the substrate in the electrodeposition solution containing the fluorescent compound. Alternatively, in embodiments where the fluorescent compound is contained in an evaluation solution different from the electrodeposition solution, this process can be performed by contacting the substrate with the evaluation solution. In this embodiment, for example, it is preferable to coat the entire or a portion of the substrate with the evaluation solution. By performing this process according to the above steps, the fluorescent compound can be adhered to the substrate, and the adhesion status of the electrodeposition solution components on the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound as an indicator.

[0039] [3: Baking and curing process]

[0040] This process includes baking and curing the substrate that has been coated in the fluorescent compound coating process.

[0041] In this process, the baking and curing temperature can be appropriately set based on the preferred baking and curing temperature of the electrodeposition solution composition applicable to this method. The baking and curing temperature is preferably in the range of 50 to 300°C, and more preferably in the range of 50 to 200°C.

[0042] In this method, when the substrate contains a foaming material, it is preferable to foam the foaming material through a baking and curing process in this step.

[0043] [4: Evaluation Process]

[0044] This process includes irradiating the baked and cured substrate obtained in the baking and curing process with the excitation light of a fluorescent compound and observing the fluorescence.

[0045] In this method, the fluorescent compound is present in the region of the substrate where the electrodeposition solution components adhere. Therefore, in this process, the adhesion state of the electrodeposition solution components on the substrate can be evaluated using the fluorescence emitted by the fluorescent compound attached to the substrate as an indicator.

[0046] The wavelength of the excitation light used in this process can be appropriately set based on the fluorescent compound used. For example, when the fluorescent compound used is anthracene, the wavelength of the excitation light is preferably in the range of 360 to 370 nm, and more preferably 365 nm.

[0047] In this process, the excitation light irradiation can be carried out using a light source such as a UV lamp that can irradiate light in the wavelength range illustrated above.

[0048] In this process, fluorescence can be observed visually or using photographic devices such as cameras.

[0049] As detailed above, by implementing this method, the adhesion status of the electrodeposition solution components on the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound adhering to the substrate as an indicator. This prevents substrates deemed to have poor electrodeposition solution adhesion from being used in the next manufacturing process. Therefore, by using this method to evaluate the adhesion status of the electrodeposition solution components on the substrate, it is possible to substantially avoid a reduction in the durability and / or reliability of the final product manufactured using that substrate.

[0050] The present invention will now be described in more detail using examples. However, the scope of the present invention is not limited to these examples.

[0051] An evaluation solution was prepared by diluting an aqueous solution containing the fluorescent compound anthracene (Super Glow Fluorescence Leakage Detector DF-300 Liquid, MARKTEC Corporation) at a content of 45 to 55% by mass to 0.1% by volume. A foaming material was then applied to a panel to prepare a substrate (material preparation step). In this embodiment, to simplify the process, a substrate without electrodeposition solution components was used. The evaluation solution was applied to the substrate to fully cover the surface of the foaming material (fluorescent compound application step). The substrate coated with the evaluation solution was positioned with the coating surface parallel to a horizontal plane (flat placement) or tilted (tilted placement), and baked and cured at 170°C for 30 minutes (baking and curing step). The foam formed by the foaming of the foaming material was removed. The obtained substrate was irradiated with 365 nm excitation light using a UV lamp, and fluorescence was observed visually (evaluation step).

[0052] exist Figure 1 The figures show photographs of substrates subjected to a bake-curing process in either a flat or tilted configuration for evaluation. In the figures, A is a photograph of the flat configuration, and B is a photograph of the tilted configuration. In the figures, areas enclosed by solid lines represent areas where fluorescence was observed, and areas enclosed by dashed lines represent areas coated with foaming material. Figure 1As shown in Figures A and B, fluorescence was observed near the interface between the foaming material and the panel in both planar and tilted orientations. Based on these results, it is concluded that the electrodeposition solution components can adhere to the vicinity of the interface between the foaming material and the panel in both planar and tilted orientations.

[0053] Furthermore, the present invention is not limited to the above embodiments, and includes various modifications. For example, the above embodiments are described in detail for the purpose of illustrating the present invention, but are not limited to having all the structures described. Moreover, it is possible to add, delete, and / or replace other structures in a part of the structure of each embodiment.

Claims

1. A method for evaluating the adhesion state of electrodeposition solution components on a substrate, the method being characterized by comprising: Material preparation process: preparing fluorescent compounds and substrates; The fluorescent compound adhesion process allows the fluorescent compound to adhere to the substrate; The baking and curing process involves baking and curing the substrate that has been adhered to during the fluorescent compound adhesion process; and The evaluation process involves irradiating the baked and cured substrate obtained in the baking and curing process with the excitation light of a fluorescent compound and observing the fluorescence.

2. The method according to claim 1, characterized in that, The fluorescent compound is contained in the electrodeposition solution. In the fluorescent compound attachment process, the fluorescent compound and the components of the electrodeposition solution are attached to the substrate together.

3. The method according to claim 1, characterized in that, The fluorescent compound is contained in an evaluation solution that is different from the electrodeposition solution. In the fluorescent compound attachment process, the fluorescent compound is attached to the substrate by contacting the substrate with the evaluation solution.

4. The method according to claim 1, characterized in that, The substrate contains foaming material.

5. The method according to claim 1, characterized in that, The fluorescent compound is anthracene.

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