Powdered paint and coated layer and coating method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a powder coating material, a coating film, and a coating method having excellent stain resistance, antibacterial property, deodorant property, water repellency, snow accretion resistance, icing resistance, corrosion resistance and lubricity.

【0002】

[Conventional technology]

If a powder coating and coating method with excellent stain resistance, antibacterial properties, deodorant properties, water repellency, snow accretion resistance, ice resistance, corrosion resistance and lubricity are found, the materials will be used for ships. Realization of energy-saving ships that reduce the frictional resistance between water and painted surfaces by applying to the water surface, metal articles that are hard to rust, antennas that are hard to snow accretion, cables, steel towers, power transmission lines or vehicles that are hard to freeze, ships, etc. It can be realized and can be widely applied to civil engineering machinery jigs. Therefore, attempts have been made to develop paints and coating methods having the above characteristics, but they have not been realized.

【0003】

[Problems to be Solved by the Invention]

The prior art paints, coatings, and coating methods have the following technical drawbacks. For example, water-repellent paints and modified fluororesin-based water-repellent materials have been developed in which a modified silicone-based resin having a contact angle with water of about 120 degrees is used as a matrix and a special metal compound is mixed and dispersed therein. Attempts were made to examine difficult-to-land snow and ice in railroad vehicles. In addition, a glass Teflon sheet is used as a material for difficult snow and ice on the communication antenna radome. However, when these water-repellent materials adhere to the surface with dust such as automobile exhaust gas and factory smoke scattered in the natural environment, the difficult-to-land snow-ice effect of the material tends to be significantly reduced. There was a problem. An object of the present invention is to solve the above-mentioned problems of the prior art, and to solve stain resistance, antibacterial property, deodorant property, water repellency, corrosion resistance, snow accretion resistance, ice resistance and lubrication. An object of the present invention is to provide a powder coating material, a coating film, and a coating method having excellent properties.

【0004】

[Means for solving problems]

To outline the present invention, the first invention of the present invention is an invention relating to a powder coating material, which is a powder coating material that forms a lower layer coating coating film and an upper layer coating coating film on an object to be coated. The fluororesin powder is characterized by containing titanium oxide powder having a photocatalytic action. Further, the second invention of the present invention is an invention relating to a coating film, which is a coating film having a two-layer structure in which a lower layer coating film and an upper layer coating film are formed on an object to be coated, and is formed on the surface of the object to be coated. It has a lower coat film, and has an upper coat film containing a titanium oxide powder having a photocatalytic action on a fluororesin on the lower coat film. Further, the third invention of the present invention is an invention relating to a method for coating a powder coating material, and the powder coating material of the above first invention is subjected to any one of baking coating, electrostatic coating, and powder coating using a fluidized immersion tank. It is characterized in that it is painted on the object to be painted.

【0005】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be specifically described. The following is a list of suitable constituent requirements in the present invention. (1) The undercoat coating film or the powder coating material forming the same is at least one of saturated polyester powder, epoxy resin powder, polyethylene powder, polyvinyl chloride powder, polyurethane powder, polyamide powder, polycarbonate powder and polyacetal powder. It is characterized by including types. (2) The upper coat coating film or the powder coating material forming the upper layer coating film is tetrafluoroethylene resin powder, perfluoro-alkoxy resin powder, tetrafluoroethylene-6fluoride propylene copolymer resin powder, or tetrafluoride. 0.5 wt% of titanium oxide powder having a photocatalytic effect on a fluororesin powder containing at least one of ethylene-ethylene copolymer resin powder, vinylidene fluoride resin powder, ethylene trifluoride chloride resin powder, and fluororubber powder. It is characterized by being mixed and dispersed in ~ 80 wt%.

【0006】

When titanium oxide powder having a photocatalytic action is dispersed in a general-purpose synthetic resin such as polyethylene, polyvinyl chloride, polyurethane, polyamide, polycarbonate, or polyacetal, those resins are easily decomposed by a photocatalytic reaction and easily deteriorate. As upper layer coat paint, tetrafluoroethylene resin powder, perfluoro-alkoxy resin powder, tetrafluoride ethylene-6fluoride propylene copolymer resin powder, tetrafluoride ethylene-ethylene copolymer resin powder, vinylidene fluoride resin powder, A powder containing 0.5 wt% to 80 wt% of titanium oxide powder having a photocatalytic action in a powder containing at least one of 3 ethylene chloride resin powder, low molecular weight tetrafluorinated ethylene resin powder, and fluorine rubber powder. The surface layer of the coated article on which the body paint is baked has an effect of decomposing contaminants adhering to the surface by a photocatalytic reaction of excited electrons and holes generated by irradiation of titanium oxide powder having a photocatalytic action with ultraviolet light.

【0007】

On the other hand, fluorine-based resins such as ethylene tetrafluoride have the largest CF interatomic bond energy of 116 kcal / mol among organic substances, are chemically extremely stable, and deteriorate due to the photocatalytic reaction of titanium oxide powder. It is difficult to do, is hydrophobic, and is not easily affected by water and moisture. Further, before the paint is directly applied to an object to be coated such as a metallic material, a ceramic material, a ceramic material such as a tile, or a lightweight concrete, a saturated polyester powder is applied to the object to be coated in advance as an undercoat and then layered. The object to be coated on which the upper coat is baked has an increased adhesion between the object to be coated and the saturated polyester coating film as compared with the object to be coated on which the paint containing the titanium oxide powder having a photocatalytic action is directly baked. Further, the fluororesin containing titanium oxide powder has the effect of decomposing the contaminants adhering to the coating film by the photocatalytic reaction as described above, but the saturated polyester coating film previously coated on the lower surface of the object to be coated On the other hand, since it has an effect of preventing deterioration of the titanium oxide powder due to a photocatalytic reaction, it can be protected from ultraviolet light. Further, the coating film having a two-layer structure has a feature that the corrosion resistance is improved.

【0008】

In the above, when titanium oxide powder having a photocatalytic action is mixed and dispersed in resins such as epoxy resin, polyethylene, polyvinyl chloride, acrylic resin, polyacetal, and polyamide, which are ordinary powder paints, the photocatalyst of titanium oxide powder having a photocatalytic action is obtained. Due to the reaction, these resins are easily photodecomposed and deteriorated, so that they have a drawback of poor durability as a coating film. The fluorine-based resin such as ethylene tetrafluoride in the present invention has a larger chemical bond energy of CF interatomic bond than the interatomic bond of CH, CN, CO, etc. of the above resin, so that it is chemically stable and can be exposed to ultraviolet light. It has the characteristic that it does not easily deteriorate. Therefore, a coating film produced by mixing and dispersing a fluororesin such as ethylene tetrafluoride powder and titanium oxide powder having a photocatalytic action and using any of baking coating, electrostatic coating, and powder coating using a fluidized immersion tank. Has the effect of decomposing the contaminants adhering to the coating film by the photocatalytic reaction as described above, and also has the feature that the coating film is less likely to deteriorate as compared with the powder coating material of general synthetic resin. Further, the coating film such as saturated polyester coated as the lower layer coating of the object to be coated not only has the effect of improving the adhesion with the upper layer coating, but also is protected from ultraviolet light by the upper layer coating, and is further formed into a coating film having a two-layer structure. As a result, it has the characteristic of improving corrosion resistance. In the examples described later, the results using the anatase-type titanium oxide powder were shown, but since the rutile-type titanium oxide powder also has a photocatalytic action, similar results were obtained.

【0009】

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

【0010】

Examples 1-27, Comparative Examples 1-9 As the undercoat paint, saturated polyester powder having an average particle size of about 70 μm was placed in a fluidized immersion tank and suspended in air to increase the apparent volume%. As the upper coat paint, the anatase-type titanium oxide powder having a photocatalytic action was changed to 0.5 wt%, 20 wt%, and 80 wt%, and the tetrafluorinated ethylene powder was mixed at the ratios of 99.5 wt%, 80 wt%, and 20 wt%, respectively. , Sufficiently mixed and stirred with a mixer to disperse to obtain a powder coating material. Further, the paint was placed in a fluidized immersion tank and suspended in air to increase the apparent bulk volume%. As an object to be coated, an aluminum plate was preheated to 400 ° C. in a heating furnace. This aluminum plate is dipped in the fluidized dipping tank containing the lower coat paint for about 3 seconds to paint, then immediately immersed in the fluidized dip tank containing the upper coat paint for 3 seconds, and then taken out into the air. It was fired and cooled as it was to prepare a coating test piece. As the lower layer coat paint, polyethylene powder, polyvinyl chloride powder, polyurethane powder, polyamide powder, polycarbonate powder, polyacetal powder, epoxy resin powder, polyvinyl chloride resin powder, and as the upper layer coat paint, perfluoro-alkoxy resin powder, The tetrafluorinated ethylene-6 fluoride propylene copolymer resin powder, tetrafluoride ethylene-ethylene copolymer resin powder, vinylidene fluoride resin powder, and ethylene trifluoride chloride resin powder were also coated on the object to be coated in the same manner. Tables 1 to 3 show a part of the list of test specimens of Examples and Comparative Examples in which the types and contents of the resin powders of the lower coat paint and the upper coat paint were changed.

【0011】

[table 1]

<img file="JPH10130540A_D0001.tif" />【0012】

[Table 2]

<img file="JPH10130540A_D0002.tif" />【0013】

[Table 3]

<img file="JPH10130540A_D0003.tif" />【0014】

In Comparative Examples 1 to 9 shown in Tables 1 to 3, the object to be coated, which had been previously heated to 400 ° C. in a heating furnace, was immersed in a fluidized immersion tank to be coated with a lower layer and an upper layer, as in the examples. .. These are obtained by coating the upper layer coat with a powder coating material that does not contain titanium oxide powder having a photocatalytic action.

【0015】

Comparative example 10 ~ 18 In Comparative Examples 10 to 18 shown in Table 4 below, the lower layer coating was not applied, and the upper layer coating containing titanium oxide was directly applied to the object to be coated.

【0016】

[Table 4]

<img file="JPH10130540A_D0004.tif" />【0017】

The water-repellent characteristics will be described below. First, the water-repellent characteristics of Examples and Comparative Examples will be described below. The contact angle of water is best known as a measure of water repellency, and the larger the angle, the higher the water repellency. Water repellency was evaluated using a contact angle meter manufactured by Kyowa Surface Chemistry Co., Ltd. Approximately 4 μl (4 × 10) on the coating film surface of the example^-9m³) Was dropped and the contact angle of water was measured. The measurement was performed at room temperature of 23 ° C, and the average value of 5 measurement points was used. As shown in FIG. 1, the initial contact angle of water was 110 to 120 degrees in both Examples and Comparative Examples. Therefore, regarding the initial water repellency, no significant difference is observed between the examples and the comparative examples.

【0018】

Next, the deterioration of the water-repellent property with time and the stain resistance of the coating film surface due to outdoor exposure of Examples and Comparative Examples were evaluated. The sample was installed on the roof of the building (Musashino City, Tokyo), and the sample was installed on the exposure table with an inclination angle of 45 ° and facing south. After the start of exposure, the sample was removed every day and exposed until 13 months had passed. The time-dependent deterioration of the water-repellent properties of this outdoor-exposed sample was evaluated by the contact angle of water. FIG. 1 is a graph showing the results of aging deterioration of water repellency due to outdoor exposure of Samples A-1 to C-1 of Examples and Comparative Examples 1 and 11. In FIG. 1, the horizontal axis represents the number of days of exposure (months), and the vertical axis represents the contact angle (degrees) of water. As shown in FIG. 1, the coating film of Comparative Example 1 containing no titanium oxide powder decreased in water repellency with the number of exposure days, and after 13 months, the contact angle of water decreased to 50 degrees or less. doing. On the other hand, the coating films of Examples A-1 to C-1 containing titanium oxide powder maintain a contact angle of 110 degrees or more with water even after 13 months. Further, in Comparative Example 11 in which the lower layer coating was not applied, the coating film was peeled off in about 10 months, and the contact angle of water decreased to 50 degrees or less.

【0019】

Next, when the coating film surface of the sample 13 months after the outdoor exposure was visually observed, the sample of Comparative Example 1 containing no titanium oxide powder had stains on the surface, and vertical rain streaks and streaks were observed. Dirt and the like left after the water droplets have dried are observed. On the other hand, in Examples A-1 to C-1 containing the titanium oxide powder, no stain was observed and the white color of the initial sample was maintained. Further, in the sample of Comparative Example 11 in which the lower layer coating was not applied, the coating film was peeled off and stains were attached.

【0020】

In order to quantify the degree of the above stains, it was evaluated with a colorimeter (SM color computer: manufactured by Suga Test Instruments Co., Ltd.) based on JIS Z 8729. Since the coating film of the present invention is all white, the degree of stain is L.^*a^*b b^*Lightness L of CIE1976 in the color system^*It was evaluated by the value of. That is, lightness L^*The higher the value of, the higher the whiteness of the coating film surface and the less the stain. FIG. 2 is a graph showing the results of stain resistance of the samples of Examples A-1 to C-1 and the samples of Comparative Example 1 and Comparative Example 11 due to outdoor exposure. In Fig. 2, the horizontal axis is the number of exposure days (months) and the vertical axis is L.^*a^*b b^*Lightness L of CIE1976 in the color system^*Means. As shown in FIG. 2, since the sample of Comparative Example 1 does not contain titanium oxide powder which is mainly used as a white pigment, the initial brightness L^*Is around 89, which is lower than in the examples, and after 13 months, the brightness is L.^*Has dropped to around 70. On the other hand, Examples A-1 to C-1 containing titanium oxide powder have a brightness of L even after 13 months.^*The decrease is small. In addition, in the sample of Comparative Example 11 in which the lower layer coat was not applied, no stain was observed until the first 2 months because the upper layer coat contained titanium oxide, but the coating film began to deteriorate in about 4 months and about 8 months. It was completely peeled off. From the above results, it was confirmed that the examples had significantly less stain on the coating film surface than the comparative examples, and the degree of adhesion of the upper coat was also high. Similar results were obtained for the powder coatings having the compositions shown in Tables 1 to 4 not only in the powder coating by the flow dipping method but also in the electrostatic coating and the baking coating.

【0021】

[Effect of the invention]

As described above, according to the present invention, the problems of the prior art have been solved, and stain resistance, antibacterial property, deodorant property, water repellency, corrosion resistance, snow accretion resistance, and difficulty It is possible to provide a powder coating material, a coating film, and a coating method having excellent icing property and lubricity.

[Simple explanation of drawings]

[Figure 1]

It is a graph which showed the result of the time-dependent deterioration of water repellency by outdoor exposure.

[Figure 2]

It is a graph which showed the evaluation result of the stain resistance of the coating film surface by outdoor exposure.