Multicolored coating film

Abstract

To provide a coating film formation method for preventing contamination from adhering to a formed multicolor coating film and maintaining multicolor appearance for a long period by applying top coating with a clear paint containing colored particulates having good water droplet sliding and falling properties after applying base painting to a wall surface of an existing building.SOLUTION: A small multi-patterned finish which is excellent in water droplet sliding and falling properties and has granite-like high quality is acquired by applying top coating of a clear paint containing colored granules containing one or more colored granules with an average particle size of 0.1 to 10 mm and a wax with a melting point of 80°C or higher and having a water slipping and falling angle (20 μL of water) of 0.5 to 30 degrees for the dried coating film on a base paint of a color different from at least one color of the colored granules over a wall surface of an existing building. Since a multicolor coating film of the present invention has good water droplet sliding and falling properties, contaminants are easily removed by a washing action of rainfall or the like. In addition, even when an exterior wall surface becomes hot due to sunlight, the wax does not melt and maintains the good water droplet slipping and falling properties so that appearance having granite-like high quality can be maintained for a long period of time.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for forming a granite-like multicolor coating film with good water droplet sliding properties on the wall surface of an existing building, which is characterized by the fact that adhering contaminants can be easily removed by the cleaning action of rainfall, etc., and that the highly designed granite-like appearance is maintained. [Background technology]

[0002] In the painting of building walls, various design innovations are implemented to enhance the design, such as stone-like paint finishes that emphasize texture. In particular, numerous techniques have been disclosed and implemented for forming coating films that create small, multicolored granite-like patterns using multicolored paints containing colored granules. Among various types of colored granules, colored gel particles, which are made by insolubilizing water-soluble polymers with a gelling agent, are particularly popular as colored granules in multicolored paints because they offer a high degree of freedom in color and size and become flat when dried.

[0003] However, various airborne contaminants, such as dust, soot, and particulate matter, exist in the atmospheric environment. These airborne contaminants are deposited on the exterior of buildings by rain, snow, wind, and other factors. Small, multicolored patterns, such as granite-like finishes, are particularly susceptible to even minute stains, potentially ruining the sophisticated design. Furthermore, multicolored paints containing colored gel particles as colored granules tend to inherently have poor water resistance, making them susceptible to contaminant deposition due to film deterioration. For this reason, several techniques have been disclosed to improve the stain resistance of small, multicolored patterned finishes containing colored gel particles: applying a clear coat over the multicolored paint (Patent Document 1); reducing the ratio of colored gel particles to the film-forming resin in the multicolored paint (Patent Document 2); and using a hydrophilic monomer in the film-forming resin of the multicolored paint (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-57186 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-277653 [Patent Document 3] Japanese Patent Application Publication No. 2019-19269 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because Patent Document 1 relies on the low-staining properties of the clear coat applied over the small-pattern multicolored paint, it does not substantially improve the low-staining properties of the small-pattern multicolored paint itself, and it also requires an additional step of applying the clear coat. Furthermore, the method of Patent Document 2 also simply relies on the resin ratio in the film-forming components of the small-pattern multicolored paint, and does not substantially improve the low-staining properties.

[0006] Generally, methods for fundamentally improving low-fouling properties include making the paint surface hydrophilic, as in the case of automobile surface coatings, and the opposite, making it water-repellent. Both methods supplement natural cleaning actions such as rainfall and forced cleaning actions such as washing with water. The former covers the paint surface with a water film during cleaning, dispersing and diffusing adhering contaminants within the water film, allowing them to be washed away along with the water film. The latter makes the paint surface water-repellent, encapsulating adhering contaminants within repelled water droplets during cleaning, removing them as the droplets slide off. Another known effect, the lotus effect, is to achieve water-repellency by closely arranging tiny hydrophobic protrusions on the paint surface, but this is difficult to implement.

[0007] Patent Document 3 describes a method for making the coating surface hydrophilic, but this method makes the coating more susceptible to the effects of water, which is a factor in coating film deterioration, and can reduce the water resistance and weather resistance of the coating film, adversely affecting the durability of the coating film. For this reason, when painting building walls, where coating film durability is a top priority, making the coating surface water-repellent is preferred as a method for facilitating the removal of adhering contaminants by the washing action of rainfall, etc.

[0008] In addition, static contact angle was previously the standard indicator for evaluating the water repellency of a coating surface. However, water sliding angle is now considered more appropriate than static contact angle for evaluating the ease with which a water droplet slides off (water droplet sliding property), and is also useful as an indicator for evaluating the removability of adhering contaminants. Here, water sliding angle is the angle at which a specified mass of water droplet begins to slide downward when the solid sample is gradually tilted. For example, the water sliding angle for a 20 μL water droplet is expressed as water sliding angle (water 20 μL). Although there is a tendency for the water sliding angle to decrease as the static contact angle increases, a surface with a high static contact angle does not necessarily have a low water sliding angle.

[0009] Therefore, the present invention aims to solve the above-mentioned problems and aims to provide a method for forming a multi-colored coating film, which is characterized by the fact that after a primer paint is applied to the wall surface of an existing building, a clear coating containing colored granules that has good water droplet sliding properties is applied on top, so that any contaminants adhering to the formed multi-colored coating film can be removed by the washing action of rainfall, etc., thereby maintaining the highly designed granite-like appearance for a long period of time. [Means for solving the problem]

[0010] To achieve this, the colored granular material-containing clear coating of the present invention contains a water-repellent wax. Wax has the property of orienting itself on the surface of the coating film as the coating film dries, thereby reducing the water sliding angle of the coating film. The colored granular material-containing clear coating of the present invention has a water sliding angle of 0.5 to 30 degrees (20 μL of water), thereby providing good water droplet sliding properties. Furthermore, the wax contained in the colored granular material-containing clear coating of the present invention has a melting point of 80°C or higher, so it is less likely to melt even when the temperature of the wall surface rises. [Effects of the Invention]

[0011] In the method for forming a multicolored coating film according to the present invention, a clear coating containing colored granules is applied over a base coating of a color different from at least one of the colored granules to obtain a sophisticated, small, and multicolored granite-like finish. Furthermore, the multicolored coating film formed by the present invention has excellent water droplet sliding properties, so even if contaminants adhere to the film, they are easily removed by the washing action of rain or other factors, and it also has excellent water resistance. Furthermore, because the wax contained in the coating has a high melting point, the wax does not melt, even when the exterior wall surface becomes hot due to strong summer sunlight, maintaining excellent water droplet sliding properties and allowing the sophisticated, granite-like appearance to be maintained for a long period of time. DETAILED DESCRIPTION OF THE INVENTION

[0012] Specific embodiments of the present invention will be described below. The coating film forming method of the present invention involves applying a base coat to the wall surface of an existing building, and then applying a top coat of a clear coat containing colored granules of one or more colors that has good water droplet sliding properties. This allows contaminants adhering to the formed granite-like multi-color coating film to be washed away by rainfall, etc., thereby maintaining the sophisticated granite-like appearance for a long period of time.

[0013] There are no particular limitations on the substrate to be painted, and it can be applied to concrete, mortar, PC panels, ALC panels, slate, siding boards, metal steel sheets, etc. Among these, siding materials with large uneven designs or designs with processed joints are preferred, as this allows for a design finish that makes the most of the design appearance. Furthermore, before applying the primer, a pre-paint suitable for the substrate can be applied as needed.

[0014] (Base coat) The primer paint for the base coat can be any general paint that has been conventionally used when painting building walls, etc., and there are no particular restrictions on this. Specifically, it can be either a water-based paint or a solvent-based paint, and its basic composition and color are not important. The primer paint is generally applied so that the dry film thickness is 5 to 500 μm. The application method can also be any conventionally known application method, without particular restrictions. For example, application can be done using a roller, brush, spatula, sponge, etc., or spray application. Among these, a paint that has a viscosity adjusted to facilitate application with a commonly used wool roller and that has a dry film thickness of 10 to 200 μm is preferred.

[0015] The primer can be applied multiple times as needed, but the first primer is applied to the entire surface of the substrate to be coated. It is also possible to create a multi-colored finish by applying a different color primer to the previous primer and intentionally applying it sparsely, leaving scattered areas unpainted. For example, on an uneven surface, a standard roller can be used to paint only the convex areas, leaving the concave areas unpainted. On a flat surface, a roller can be used to create scattered, protruding islands of paint (painted areas). Alternatively, scattered areas can be left unpainted by partially masking the area.

[0016] (Top coat) After the base coat is applied, a clear coat containing colored granules (top coat) is applied. The clear coat that serves as the base of this coat (before the colored granules and wax are mixed) is not particularly limited in composition, as long as it is a clear coat that has been conventionally used in this field, and may be a colorless, transparent clear coat or a colored, transparent, colored clear coat.

[0017] The film-forming resin for the topcoat paint can be a synthetic resin such as an acrylic resin, an acrylic styrene resin, an acrylic silicone resin, a silicone resin, a urethane resin, a fluororesin, a chlorinated vinyl resin, a vinyl acetate resin, an epoxy resin, a melamine resin, an alkyd resin, a polyester resin, or a modified product thereof. These film-forming resins can be used alone or in combination of two or more. These film-forming resins can be dissolved in an organic solvent or emulsion-polymerized in water to form an aqueous dispersion. Among these, acrylic resin-based or acrylic silicone resin-based synthetic resin emulsions are preferred from the standpoints of ease of handling, safety, film performance, cost, etc.

[0018] The solid content of the film-forming resin contained in the topcoat paint is preferably 1 to 60 wt%, more preferably 5 to 50 wt%, and even more preferably 10 to 40 wt%. If the resin solid content in the paint is too low, it may be difficult to ensure a certain dry film thickness, and it may be difficult to achieve the effect of making the unevenness of a multicolored pattern less noticeable. On the other hand, if the resin solid content in the paint is too high, the paint viscosity may become too high, making application difficult and the paint stability may also be reduced.

[0019] In addition, the topcoat paint may also contain viscosity imparting agents, anti-settling agents, dispersants, antifoaming agents, preservatives, mildew inhibitors, ultraviolet absorbers, light stabilizers, rust inhibitors, gloss adjusters, etc., as needed, within the scope of not impairing the effects of the present invention.

[0020] The topcoat paint contains colored granules to impart a sophisticated granite-like appearance. Examples of colored granules that can be used include crushed silica sand, glass, or ceramics, colored materials such as mica powder, as well as color chips made from plastic materials or colored gel particles. Colored gel particles are particularly preferred because they offer a high degree of freedom in color and size, and become flat when dried, resulting in a flat and smooth coating film overall. Colored gel particles can be prepared by known methods.

[0021] The average particle size of the colored granules is 0.1 to 10 mm, preferably 0.2 to 5 mm, and more preferably 0.3 to 2 mm. If the particle size of the colored granules is too small, it is difficult to obtain the small, colorful granite-like texture. On the other hand, if the particle size of the colored granules is too large, the presence of the colored granules becomes conspicuous, and the texture of the small, colorful granite-like texture is damaged.

[0022] The amount of colored granules to be blended is 1 to 60% by weight, preferably 2 to 40% by weight, and more preferably 5 to 20% by weight, based on 100% by weight of the paint. If the amount of colored granules is too small, it is difficult to obtain the small, colorful granite-like pattern. On the other hand, if the amount of colored granules to be blended is too large, the presence of the colored granules becomes noticeable, which in turn impairs the texture of the small, colorful granite-like pattern.

[0023] Furthermore, the clear paint containing colored granules, which is the top coat, contains wax. The melting point of the wax is 80°C or higher, preferably 90°C or higher, and more preferably 100°C or higher. If the wax has a low melting point, when the surface temperature of the building exterior wall, which is the painted area, rises, the wax melts, making it easier for contaminants to adhere, which in turn accelerates contamination.

[0024] Examples of such waxes include paraffin wax, microcrystalline wax, montan wax, polyethylene wax, polypropylene wax, Fischer-Tropsch wax, ethylene-vinyl acetate copolymer wax, ethylene-acrylic acid copolymer wax, beeswax, carnauba wax, lanolin wax, and modified products thereof, and one or more of these may be used. Furthermore, a wax having a melting point of less than 80°C may be used supplementarily in combination to the extent that the low-staining properties of the topcoat paint are not impaired.

[0025] Wax can be in the form of a wax dispersed in water (water-dispersed wax), a wax dissolved or dispersed in an organic solvent, or a wax pulverized into a powder. In particular, when the top coat is water-based, commercially available water-dispersed wax is preferred because it can be easily mixed and dispersed in the paint.

[0026] The wax content is 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 1 part by weight, per 100 parts by weight of the solids content of the film-forming resin in the topcoat paint. If the content is less than 0.01 part by weight, sufficient water droplet sliding properties cannot be obtained, while if the content exceeds 10 parts by weight, excessive water repellency results, reducing adhesion to the base paint and even causing poor adhesion of the paint to be repainted.

[0027] The topcoat paint can further contain a flat luster pigment to impart a lustrous appearance to the coating film, making it look more like granite. Examples of such flat luster pigments include pearl mica, mica powder, aluminum flakes, stainless steel flakes, titanium flakes, glass flakes, and interference film pieces.

[0028] The topcoat paint of the present invention has a water sliding angle (20 μL of water) of 0.5 to 30 degrees, preferably 1 to 15 degrees. If the water sliding angle (20 μL of water) exceeds 30 degrees, the water droplet sliding property is insufficient. On the other hand, if the water sliding angle (20 μL of water) is less than 0.5 degrees, the water repellency becomes excessive, which reduces adhesion to the base paint and further causes poor adhesion of the paint when repainted.

[0029] The top coat paint has a dry film thickness of 5 to 200 μm, preferably 10 to 100 μm. If the paint film thickness (amount applied) is too small, it is difficult to obtain the granite-like small, colorful pattern. On the other hand, if the paint film thickness (amount applied) is too large, the texture of the granite-like small, colorful pattern will be lost. Like the base coat, the top coat paint can be applied with a roller or brush, or it can be sprayed.

Claims

1. This method for forming a multicolored coating film is characterized by applying a clear coating containing colored granules of one or more colors with an average particle size of 0.1 to 10 mm and a wax having a melting point of 80°C or higher, and having a water sliding angle (20 μL of water) of 0.5 to 30 degrees for the dried coating film, to the wall surface of an existing building, over a base coating of a color different from at least one of the colors of the colored granules.

2. 2. The method for forming a multicolored coating film according to claim 1, wherein the colored particles are colored gel particles.

3. The method for forming a polychromatic coating film according to claim 1 or 2, characterized in that two or more colors of primer paint are applied in layers, and the layers other than the first primer paint are applied sparsely, leaving scattered areas unpainted, thereby giving the primer paint a polychromatic finish.