Method for evaluating the adhesion state of electrodeposition solution components

Abstract

This invention provides a means for easily evaluating the adhesion state of electrodeposition solution components to a substrate. [Solution] One aspect of the present invention relates to a method for evaluating the adhesion state of electrodeposition solution components to a substrate, comprising a material preparation step of preparing a fluorescent compound and a substrate; a fluorescent compound adhesion step of adhering the fluorescent compound to the substrate; a baking step of baking the substrate with the adhesive applied in the fluorescent compound adhesion step; and an evaluation step of irradiating the baked substrate obtained in the baking step with excitation light of the fluorescent compound and observing the fluorescence.

Description

Technical Field

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[0001] The present invention relates to a method for evaluating the adhesion state of electrodeposition liquid components.

Background Art

[0002] Electrodeposition is a technique for adhering electrodeposition liquid components to a substrate by bringing an electrodeposition liquid into contact with the substrate (for example, immersing the substrate in the electrodeposition liquid) and passing an electric current between the substrate and a counter electrode. For example, when the electrodeposition liquid component is paint, it is also called electrodeposition coating.

[0003] As a measurement technique for electrodeposition liquid components, for example, Patent Document 1 discloses a method for measuring the fluororesin concentration in an electrodeposition coating bath, which comprises collecting a part of the electrodeposition coating as a measurement sample from a coating bath composed of an electrodeposition coating containing a fluororesin having a chlorine atom and other resins as resin components, coating the measurement sample on a metal test plate by an electrodeposition coating method, and measuring the chlorine atom concentration in the obtained coating film by a fluorescent X-ray analysis method.

[0004] Patent Document 2 describes a continuous electrodeposition coating apparatus having an ultrafiltration filter made of an inorganic compound as a concentration means for an electrodeposition liquid, a metal ion removal means using a chelate fiber having cellulose as a base material, and a drying and baking means in the same system, and a device capable of controlling the electrodeposition liquid concentration in an electrodeposition tank by measuring it by UV spectroscopic analysis and performing feedback.

[0005] Patent Document 3 describes a method for quantitatively evaluating the surface state of an electrodeposited metal plate obtained by electrolytically collecting or electrolytically refining a non-ferrous metal from an electrolytic solution containing the non-ferrous metal, which comprises photographing the surface of the electrodeposited metal plate by photographing means, calculating the value of the standard deviation σ of the luminance distribution of the obtained image by calculating means, and evaluating the surface state of the electrodeposited metal plate from that value.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-197296 [Patent Document 2] Japanese Patent Publication No. 2005-336559 [Patent Document 3] Japanese Patent Publication No. 2013-181911 [Overview of the project] [Problems that the invention aims to solve]

[0007] In electrodeposition, areas where the electrodeposition solution components are not substantially adhered may occur due to the shape and / or material of the substrate. For example, in the case of a substrate in which a foam material is bonded to a conductive material, the electrodeposition solution components may not uniformly adhere to the gaps at the interface between the foam, which is formed by foaming the foam material, and the conductive material. These areas where the electrodeposition solution components are not adhered may rust when the exposed substrate is exposed to the external environment (e.g., oxygen and moisture). The occurrence of rust accelerates the deterioration of the substrate, thereby reducing the durability and / or reliability of the final product manufactured using the substrate. However, there was no known method for easily evaluating the adhesion state of the electrodeposition solution components to the substrate.

[0008] Therefore, the present invention aims to provide a means for easily evaluating the adhesion state of electrodeposition solution components to a substrate. [Means for solving the problem]

[0009] The inventors investigated various means to solve the above-mentioned problems. The inventors found 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 to the substrate can be easily evaluated using the fluorescence as an indicator. Based on the above findings, the inventors completed the present invention.

[0010] In other words, the present invention encompasses the following aspects and embodiments. (Embodiment 1) A method for evaluating the adhesion state of electrodeposition solution components to a substrate, Material preparation process for preparing fluorescent compounds and substrates, A fluorescent compound deposition process, which involves attaching a fluorescent compound to a substrate. The fluorescent compound is applied to the substrate obtained in the application process, and then baked in the baking process. Evaluation process: Irradiating the baked substrate obtained in the baking process with excitation light of a fluorescent compound and observing the fluorescence. The method, including the method described above. (Embodiment 2) The method according to Embodiment 1, wherein the fluorescent compound is contained in the electrodeposition solution, and in the fluorescent compound attachment step, the fluorescent compound is attached to the substrate together with the electrodeposition solution components. (Embodiment 3) The method according to Embodiment 1, wherein the fluorescent compound is contained in an evaluation solution separate from the electrodeposition solution, and the fluorescent compound is attached to the substrate by bringing the substrate into contact with the evaluation solution in the fluorescent compound attachment process. (Embodiment 4) The method according to any one of Embodiments 1 to 3, wherein the base material includes a foaming material. (Embodiment 5) The method according to any one of Embodiments 1 to 4, wherein the fluorescent compound is anthracene. [Effects of the Invention]

[0011] The present invention provides a means for easily evaluating the adhesion state of electrodeposition solution components to a substrate. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows photographs of substrates subjected to the baking process in either a flat or diagonal arrangement in the examples, which were then subjected to the evaluation process. In the figure, A is a photograph of the flat arrangement, and B is a photograph of the diagonal arrangement. In the figure, the area enclosed by the solid line indicates the area where fluorescence was observed, and the area enclosed by the dotted line indicates the area where the foaming material was applied. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention will be described in detail below.

[0014] One aspect of the present invention relates to a method for evaluating the adhesion state of an electrodeposition liquid component to a substrate.

[0015] In each aspect of the present invention, the electrodeposition liquid component is a component dissolved or dispersed in the electrodeposition liquid and means a component to be adhered to the substrate by electrodeposition. For example, in the case of electrodeposition coating, the electrodeposition liquid component is a paint component. The electrodeposition liquid is a solution or dispersion liquid containing the electrodeposition liquid component exemplified above. The solvent of the electrodeposition liquid is preferably water or one or more water-miscible organic solvents, or a mixture thereof.

[0016] In each aspect of the present invention, the substrate may be formed of a conductive material made of a conductive material commonly used for electrodeposition in the art. The shape of the substrate is not particularly limited. The substrate may include a material made of one or more resins in addition to the conductive material. Examples of such a material made of resin include foams made of thermoplastic resins such as polyethylene, polystyrene, polypropylene, or polyurethane. The substrate prepared in this step has, for example, a conductive material and a foam joined to the surface of the conductive material. In the case of a substrate in which a foam is joined to a conductive material, the electrodeposition liquid component may not adhere uniformly to the gap at the joining interface between the foam generated by foaming the foam and the conductive material. By implementing the method of this aspect, even for such a substrate, the adhesion state of the electrodeposition liquid component to the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound adhered to the substrate as an index.

[0017] The method of this aspect includes a material preparation step, a fluorescent compound adhesion step, a baking step, and an evaluation step. Each step will be described in detail below.

[0018] [1: Material preparation step] This step includes preparing a fluorescent compound and a substrate.

[0019] In each aspect of the present invention, the fluorescent compound is not particularly limited as long as it 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 carrying out the method of this aspect using the fluorescent compound exemplified above, the adhesion state of the electrodeposition solution components to the substrate can be easily evaluated based on the fluorescence emitted by the fluorescent compound adhered to the substrate.

[0020] The fluorescent compound may be contained in the electrodeposition solution to which the method of this aspect is applied, or may be contained in an evaluation solution different from the electrodeposition solution to which the method of this aspect is applied. In the case of the latter embodiment, it is preferable that the solvent of the evaluation solution is substantially the same as the solvent used in the electrodeposition solution. Such an evaluation solution is expected to have substantially the same adhesion behavior to the substrate as the electrodeposition solution. Therefore, by carrying out the method of this aspect in any embodiment, the adhesion state of the electrodeposition solution components to the substrate can be easily evaluated based on the fluorescence emitted by the fluorescent compound adhered to the substrate.

[0021] The concentration of the fluorescent compound in the electrodeposition solution or the 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, etc. The concentration of the fluorescent compound is preferably in the range of 0.001 to 1% by mass, and more preferably in the range of 0.01 to 0.1% by mass.

[0022] The fluorescent compound and the substrate prepared in this step may be materials having the characteristics described above. Each material may be prepared by itself having a predetermined characteristic, or may be prepared by purchasing a commercially available product or the like.

[0023] [2: Fluorescent Compound Adhesion Step] This step includes adhering a fluorescent compound to a substrate.

[0024] In embodiments where the fluorescent compound is contained in the electrodeposition solution, this step can be carried out by attaching the fluorescent compound to the substrate together with the electrodeposition solution components. 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 separate from the electrodeposition solution, this step can be carried out by bringing the substrate into contact with the evaluation solution. In this embodiment, for example, it is preferable to apply the evaluation solution to the entire or a part of the substrate. By carrying out this step in the above procedure, the fluorescent compound is attached to the substrate, and the adhesion state of the electrodeposition solution components to the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound as an indicator.

[0025] [3: Baking process] This process includes baking the substrate with the fluorescent compound already attached, obtained in the fluorescent compound attachment process.

[0026] In this process, the curing temperature can be appropriately set based on the preferred curing temperature of the electrodeposition solution component to which the method of this embodiment is applied. The curing temperature is preferably in the range of 50 to 300°C, and more preferably in the range of 50 to 200°C.

[0027] In the method of this embodiment, if the base material includes a foaming agent, it is preferable to foam the foaming agent by the baking process in this step.

[0028] [4: Evaluation Process] This process includes irradiating the baked substrate obtained in the baking process with excitation light of a fluorescent compound and observing the fluorescence.

[0029] In the method of this embodiment, the fluorescent compound is present in the region of the substrate where the electrodeposition solution component is attached. Therefore, in this process, the state of attachment of the electrodeposition solution component to the substrate can be evaluated using the fluorescence emitted by the fluorescent compound attached to the substrate as an indicator.

[0030] The wavelength of the excitation light irradiated in this process can be appropriately set based on the fluorescent compound used. For example, if 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.

[0031] In this process, the irradiation of excitation light can be carried out using a light source such as a UV light that can emit light in the wavelength range exemplified above.

[0032] In this process, fluorescence may be observed visually or using a camera or other imaging device.

[0033] As described in detail above, by implementing the method of this embodiment, the adhesion state of the electrodeposition solution components to the substrate can be easily evaluated using the fluorescence emitted by the fluorescent compound attached to the substrate as an indicator. This makes it possible to avoid using substrates that have been evaluated as having poor adhesion of the electrodeposition solution components in the next manufacturing process. Therefore, by evaluating the adhesion state of the electrodeposition solution components to the substrate using the method of this embodiment, a decrease in the durability and / or reliability of the final product manufactured using the substrate can be substantially avoided. [Examples]

[0034] The present invention will be described in more detail below using examples. However, the technical scope of the present invention is not limited to these examples.

[0035] An evaluation solution was prepared by diluting an aqueous solution containing 45 to 55% by mass of the fluorescent compound anthracene (Super Glow Fluorescent Leakage Inspection Agent DF-300 Liquid, Marktec Co., Ltd.) to 0.1% by volume. A substrate was prepared by coating a foaming material onto a panel (material preparation step). In this example, a substrate without electrodeposition solution was used to simplify the procedure. The evaluation solution was applied to the substrate so as to sufficiently cover the surface of the foaming material (fluorescent compound application step). The substrate coated with the evaluation solution was placed so that the coated surface was parallel to the horizontal plane (flat placement) or at an angle (angled placement), and baked at 170°C for 30 minutes (baking 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 light, and fluorescence was observed visually (evaluation step).

[0036] Figure 1 shows photographs of substrates subjected to the baking process in either a flat or oblique orientation for evaluation. In the figure, A is a photograph of the flat orientation, and B is a photograph of the oblique orientation. In the figure, the area enclosed by the solid line indicates the area where fluorescence was observed, and the area enclosed by the dotted line indicates the area where the foam material was applied. As shown in Figures 1A and 1B, in both the flat and oblique orientations, the fluorescence region was observed up to the vicinity of the interface between the foam material and the panel. From these results, it was evaluated that the electrodeposition solution can adhere up to the vicinity of the interface between the foam material and the panel in both the flat and oblique orientations.

[0037] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. In addition, it is possible to add, delete, and / or replace some of the configurations in each embodiment with other configurations.

Claims

1. A method for evaluating the adhesion state of electrodeposition solution components to a substrate, Material preparation process for preparing fluorescent compounds and substrates, A fluorescent compound deposition process, which involves attaching a fluorescent compound to a substrate. The fluorescent compound is applied to the substrate obtained in the application process, and then baked in the baking process. Evaluation process: Irradiating the baked substrate obtained in the baking process with excitation light of a fluorescent compound and observing the fluorescence. The method, including the method described above.

2. The method according to claim 1, wherein a fluorescent compound is contained in the electrodeposition solution, and in the fluorescent compound deposition step, the fluorescent compound is deposited on the substrate together with the electrodeposition solution components.

3. The method according to claim 1, wherein the fluorescent compound is contained in an evaluation solution separate from the electrodeposition solution, and in the fluorescent compound attachment process, the fluorescent compound is attached to the substrate by bringing the substrate into contact with the evaluation solution.

4. The method according to claim 1, wherein the base material includes a foaming agent.

5. The method according to claim 1, wherein the fluorescent compound is anthracene.

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