Coating Method

Abstract

To provide a coating method capable of applying a coating having excellent adhesive strength and good appearance to an object to be coated. At least a surface portion of an object to be coated (1) made of metal is subjected to plasma treatment, and then the surface portion is coated by hydrogen bonding.

Description

[Technical Field]

[0001] The present disclosure relates to coating methods. [Background technology]

[0002] Patent Document 1 discloses a faucet. The base material of this faucet is provided with a nickel-plated layer and a chrome-plated layer as corrosion-resistant layers. On the corrosion-resistant layer, a primer layer made from a one-component fluorine-based paint and a top coat layer made from a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer are formed as antifouling layers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-030707 Summary of the Invention [Problem to be solved by the invention]

[0004] The antifouling layer has a primer layer to improve adhesion of the top coat layer, but because it is necessary to form two layers, a primer layer and a top coat layer, the thickness of the entire antifouling layer varies and is difficult to make uniform, making it difficult to provide a coating that looks good on the object to be coated.

[0005] The present disclosure has been made in view of the above-mentioned circumstances, and aims to provide a coating method capable of performing a coating with excellent adhesive strength and reduced thickness variation. [Means for solving the problem]

[0006] A coating method according to one aspect of the present disclosure includes performing plasma treatment on a surface portion of an object to be coated, at least the surface portion of which is made of metal, and then coating the surface portion by hydrogen bonding. [Effects of the Invention]

[0007] A coating method according to one aspect of the present disclosure can produce a coating with excellent adhesive strength and reduced thickness variation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an object to be coated according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the object to be coated and the coating layer. [Figure 3] FIG. 3 is an explanatory view showing a schematic diagram of the bonding state between the coating object and the coating agent in the same. [Figure 4] FIG. 4 is an explanatory view showing a schematic diagram of the plasma treatment process of the object to be coated in the above embodiment. [Figure 5] FIG. 5 is an explanatory view schematically showing plasma treatment of the coating object by the atmospheric pressure plasma treatment apparatus. [Figure 6] FIG. 6 is an explanatory view schematically showing a surface portion of the above-mentioned object to be coated before plasma treatment. [Figure 7] FIG. 7 is an explanatory view schematically showing the surface portion of the above-mentioned coating object after plasma treatment. [Figure 8] FIG. 8 is a perspective view showing another example of an object to be coated. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure relates to a coating method, and more particularly to a coating method for applying a coating to an object to be coated.

[0010] (1) Implementation form In the coating method of this embodiment, for example, coating is performed on a coating target 1 shown in FIG. 1. The coating target 1 shown in FIG. 1 is a faucet, and is installed, for example, in a kitchen. However, the coating target 1 is not limited to this. For example, the coating target 1 may be a faucet installed in a bathroom, etc., as shown in FIG. 8. The faucet serving as the coating target 1 may also be, for example, other faucets installed in a washroom, toilet, etc. Furthermore, the coating target 1 is not limited to a faucet, but may also be other plumbing equipment such as a sink, kitchen counter, or bathtub. Furthermore, the coating target 1 is not limited to plumbing equipment, but may also be, for example, a handle, a lighting fixture, or an in-vehicle equipment. Furthermore, in the present disclosure, "coating" means covering at least a portion of the surface of the coating target 1 with a fixable substance, and is not limited to coating the entire surface of the coating target 1.

[0011] 2 shows a cross-sectional view of a coated object 1. Reference numeral 2 in the figure denotes a coating layer formed by coating.

[0012] At least the surface portion of the object to be coated 1 is made of metal. The object to be coated 1 comprises a substrate 10 and a surface layer 11. The substrate 10 constitutes the main body of the object to be coated 1 and has a three-dimensional shape. The substrate 10 is made of synthetic resin, more specifically, ABS (Acrylonitrile butadiene styrene) resin. The surface layer 11 covers the surface of the substrate 10. In this embodiment, the surface layer 11 is the surface portion of the object 1 to be coated.

[0013] The surface layer 11 (surface portion) is a metal layer formed on the surface of the substrate 10. In the coating object 1 of this embodiment, only the surface portion is formed from metal. The surface layer 11 is chrome plating, and has abrasion resistance, impact resistance, corrosion resistance, gloss, etc. The chrome plating is, for example, hard chrome plating or black chrome plating. The surface layer 11 is formed, for example, over the entire surface of the substrate 10.

[0014] The substrate 10 may be formed from a synthetic resin other than ABS resin, or from a material other than synthetic resin. Examples of materials other than synthetic resin include ceramic, glass, and metal. The surface layer 11 may be plated with a material other than chrome plating. The surface layer 11 may be zinc plated or nickel plated, for example. The plating method for the surface layer 11 is not limited. The plating method for the surface layer 11 may be hot-dip plating, vapor plating, electroplating, chemical plating, or the like. The surface layer 11 may be a metal layer formed by lamination, vapor deposition, sputtering, or the like, instead of plating. The surface layer 11 may be formed only on a portion of the surface of the substrate 10. The object 1 to be coated is not limited to an object having only its surface made of metal, and the entire object 1 to be coated may be made of metal.

[0015] In this embodiment, the coating layer 2 is formed on the surface of the surface layer 11, which is the surface portion of the object 1 to be coated, by directly applying a coating.

[0016] The coating agent 20 (see FIG. 3) that forms the coating layer 2 is a fluororesin composition containing a fluororesin. That is, in this embodiment, the surface of the object 1 to be coated is coated with a fluororesin to form the coating layer 2 made of the fluororesin composition. The fluororesin may be, for example, PTFE (polytetrafluoroethylene), PFA (perfluoroethylene), or the like. fluoroalkoxyalkane), PFEP (perfluoroethylene propene copolymer), ETFE (ethylene tetrafluoroethylene copolymer), ECTFE (ethylene chlorotrifluoroethylene copolymer), or PVDF (polyvinylidene fluoride). Various additives may be added to the fluororesin composition as needed.

[0017] Next, the coating method of this embodiment will be described. The coating method of this embodiment includes a plasma treatment step and a coating step. The plasma treatment step is a step preceding the coating step. The plasma treatment step is a step of performing plasma treatment on a surface layer 11, which is the surface portion of the object 1 to be coated. The coating step is a step of performing a coating by hydrogen bonding on the surface layer 11 of the object 1 to be coated that has been plasma-treated in the plasma treatment step.

[0018] In the plasma treatment step, a plasma treatment is performed on the object 1 to be coated using, for example, a plasma treatment apparatus 3 shown in FIG. 4. The plasma treatment apparatus 3 is a vacuum plasma (low-pressure plasma) treatment apparatus that performs plasma treatment (vacuum plasma treatment) on the object 1 to be coated in a plasma treatment chamber that has been depressurized to a pressure lower than atmospheric pressure. The vacuum plasma treatment using the plasma treatment apparatus 3 is performed by placing the object 1 to be coated between a pair of electrodes 30, 30 in the depressurized plasma treatment chamber and applying a voltage between the pair of electrodes 30, 30 from an AC or DC power source. This causes the surface layer 11 of the object 1 to be coated to be irradiated with plasma (more specifically, electrons and ions of the plasma generated in the plasma treatment chamber). This plasma treatment is performed, for example, in a state where the plasma treatment chamber is filled with process gases, argon and oxygen. The process gas is supplied into the plasma treatment chamber after the plasma treatment chamber is depressurized using a vacuum pump, for example, to fill the plasma treatment chamber. It should be noted that the term "vacuum plasma treatment" refers to plasma treatment performed under a reduced pressure below atmospheric pressure, and is not limited to plasma treatment performed in a vacuum atmosphere.

[0019] In vacuum plasma treatment, the plasma bounces off the gas in the plasma treatment chamber, allowing it to be uniformly irradiated over the entire surface of the object 1 to be coated. This makes it suitable for plasma treatment of the surface of an object 1 to be coated that has a three-dimensional shape, such as a faucet. There are no restrictions on the process gas that can be filled into the plasma treatment chamber.

[0020] The plasma treatment carried out in the plasma treatment step is not limited to vacuum plasma treatment, but may be atmospheric pressure plasma treatment in which plasma treatment is carried out under atmospheric pressure. An example of an atmospheric pressure plasma treatment apparatus 4 is shown in FIG.

[0021] In the atmospheric pressure plasma processing apparatus 4, plasma processing is performed, for example, by placing the object to be coated 1 between a pair of electrodes 40, 40 in an atmospheric pressure atmosphere and applying a voltage between the pair of electrodes 40, 40 from an AC or DC power supply. In plasma processing using this atmospheric pressure plasma processing apparatus 4, plasma is irradiated linearly from one of the pair of electrodes 40, 40 to the other. Therefore, when the surface of the object to be coated 1 to be plasma processed is flat, it is advantageous because it can omit equipment for forming a reduced pressure space, such as a plasma processing chamber or a vacuum pump.

[0022] As shown in Fig. 6, before the plasma treatment step is performed, the surface of the surface layer 11 of the object to be coated 1 usually contains only a small amount of hydroxyl groups for hydrogen bonding the coating agent 20 to the surface layer 11. For this reason, even if the surface layer 11 is coated by hydrogen bonding, it is difficult to increase the adhesive strength of the coating agent 20 to the object to be coated 1. However, in this embodiment, the surface layer 11 of the object to be coated 1 is plasma-treated in the plasma treatment step, and the chemical bonds of molecules contained in the oxide film, etc. of the surface layer 11 are strengthened. is cleaved, and as a result, a large number of hydroxy groups are formed on the surface of the surface layer 11, as shown in Figure 7. This makes it possible to perform coating by hydrogen bonding on the surface layer 11 with increased adhesive strength.

[0023] In the plasma treatment process performed by the plasma treatment device 3, the plasma treatment of the coating object 1 is preferably performed at an output of 100 W or more and 500 W or less for a time period of 10 seconds or more and 60 seconds or less. In this case, the adhesive strength of the coating agent 20 to the surface layer 11 can be sufficiently increased while suppressing energy consumption. The plasma treatment of the coating object 1 is performed, for example, for 30 seconds at an output of 250 W. The power output during the plasma treatment and the treatment time are not limited.

[0024] After the plasma treatment step, a coating step is performed. The coating step is performed, for example, outside the plasma treatment chamber. Alternatively, the coating step may be performed inside the plasma treatment chamber.

[0025] In the coating step, the coating agent 20 (see FIG. 3) containing the above-mentioned fluororesin is directly coated onto the surface of the surface layer 11 that has been plasma-treated in the plasma treatment step. As a result, the coating agent 20 is hydrogen-bonded to the object 1 to be coated, as shown in FIG. 3. Coating of the object 1 to be coated is performed using, for example, a spray gun or an electrostatic powder coating machine. Note that the method for coating the object 1 to be coated is not limited.

[0026] By performing coating in the coating process, the properties of the coating agent 20 can be imparted to the object 1. The coating agent 20 of this embodiment contains a fluororesin, and therefore imparts properties such as water and oil repellency (fouling resistance), heat resistance, chemical resistance, and abrasion resistance to the object 1.

[0027] The coating agent 20 does not have to contain a fluororesin as long as it can form hydrogen bonds with the metal surface portion of the coating target 1. Examples of the coating agent 20 that does not contain a fluororesin include coating agents that contain an acrylic resin or a silicone resin. Alternatively, the coating agent 20 that does not contain a fluororesin may be a coating agent that contains a ceramic such as silicon carbide.

[0028] According to the coating method of this embodiment, plasma treatment of the object 1 allows the formation of numerous hydroxyl groups on the surface of the object 1. Then, the surface, which now has a greater number of hydroxyl groups than before the plasma treatment, is coated by hydrogen bonding. This allows the formation of a coating layer 2 (see FIG. 2) with high adhesive strength on the object 1. Furthermore, in this case, the surface of the object 1 can be directly coated with the coating agent 20 without forming a primer layer. In other words, it is sufficient to form only a single layer, the coating layer 2, on the surface of the object 1.

[0029] (2) Mode As is clear from the above-described embodiments, the coating method of the first aspect has the following configuration: A plasma treatment is performed on at least the surface portion (e.g., the surface layer 11) of an object to be coated (1), the surface portion of which is made of metal, and then the surface portion is coated by hydrogen bonding.

[0030] According to this embodiment, by subjecting the object to be coated (1) to plasma treatment, hydroxy groups for carrying out coating by hydrogen bonding are provided on the surface portion of the object to be coated (1). It is possible to form a large number of layers. This allows for a coating with excellent adhesive strength to be applied to the object to be coated (1). Furthermore, since the coating is applied directly to the surface of the object to be coated (1), a primer layer can be omitted. This allows for a smaller thickness of the layer formed on the surface of the object to be coated, and also suppresses variations in the thickness of this layer. This allows for a coating with a good appearance. Furthermore, since the step of forming a primer layer can be omitted, the coating can be easily performed.

[0031] The coating method of the second aspect can be realized in combination with the coating method of the first aspect. In the second aspect, the plasma treatment is a vacuum plasma treatment.

[0032] According to this embodiment, the object (1) to be coated, which has a three-dimensional shape, can be uniformly coated.

[0033] The coating method of the third aspect can be realized in combination with the method of the second aspect. In the third aspect, the plasma treatment is carried out at an output of 100 W or more and 500 W or less for 10 seconds or more and 60 seconds or less.

[0034] According to this aspect, it is possible to perform a coating with high adhesive strength while suppressing energy consumption.

[0035] The coating method of the fourth aspect can be realized in combination with any one of the aspects 1 to 3. In the fourth aspect, the coating is a fluorine coating.

[0036] According to this embodiment, it is possible to impart water- and oil-repellency (fouling resistance), heat resistance, chemical resistance, abrasion resistance, and the like to the object to be coated (1).

[0037] The coating method of the fifth aspect can be realized in combination with any one of the aspects 1 to 4. In the fifth aspect, the object to be coated (1) is a faucet.

[0038] According to this aspect, a coating can be applied to the faucet that has excellent adhesive strength and reduced thickness variation.

[0039] The coating method of the sixth aspect can be realized by combining it with the fifth aspect. The sixth aspect has the following configuration. The faucet comprises a resin base material (10) and a chrome plating layer applied to the surface of the base material (10). The surface portion is the chrome plating layer.

[0040] According to this aspect, a coating with excellent adhesive strength and reduced thickness variation can be applied to a faucet whose surface is a chrome-plated layer. [Explanation of symbols]

[0041] 1. Coating object 10 Base material 11 Surface layer (surface part)

Claims

1. A method for coating a surface of an object to be coated, at least a surface of which is made of metal, by subjecting the surface to plasma treatment, and then coating the surface by hydrogen bonding. Coating method.

2. The plasma treatment is a vacuum plasma treatment. The coating method according to claim 1.

3. The plasma treatment is carried out for 10 seconds to 60 seconds at an output of 100 W or more and 500 W or less. The coating method according to claim 2.

4. The coating is a fluorine coating. The coating method according to any one of claims 1 to 3.

5. The object to be coated is a faucet. The coating method according to any one of claims 1 to 4.

6. The faucet is A resin base material; A chrome plating layer is provided on the surface of the base material, The surface portion is the chrome plating layer. The coating method according to claim 5.

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