Coating composition, coating film, and method for producing coating film

Abstract

The coating composition includes: heteromorphic silica particles having an average particle diameter of 12 nm to 250 nm; hydrophobic resin particles having an average particle diameter of 50 nm to 500 nm; and poorly water-soluble anti-mildew particles having rod-like, needle-like or fibrous crystallinity and having a crystal length of 1 [mu] m to 10 mm inclusive and a crystal thickness of 0.1 [mu] m to 15 [mu] m inclusive. A liquid mixture obtained by mixing the heteromorphic silica particles, the hydrophobic resin particles, the water, and the anti-mildew particles is alkaline having a pH of 9 to 11.

Description

Technical Field

[0001] This disclosure relates to a coating composition formed on a substrate or the like, a coating film, and a method for manufacturing the coating film. Background Technology

[0002] In indoor spaces, due to cold radiation from sources such as freezers or refrigerators, the ceilings or walls surrounding them are cooled, and combined with warm air flowing in from the outside, condensation can easily occur. Additionally, condensation or grime is frequently observed on ceilings or walls near air conditioner vents. In such places, mold easily grows due to the moisture from the condensation or grime; therefore, given the increasing demands for cleanliness in recent years, measures to inhibit mold growth are needed.

[0003] As a countermeasure to suppress mold growth, the following technologies have been developed: optimizing air conditioning capacity to create an environment free from condensation, dirt, and mold that causes them. Patent Document 1 discloses a method of containing a non-water-soluble anti-mold agent in gypsum board used as a ceiling material. Furthermore, Patent Document 2 discloses a technology that imparts stain resistance and antibacterial properties by using an aqueous coating agent composed of photocatalytic oxides, hydrophobic resin emulsions, and silica particles.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5520603

[0007] Patent Document 2: Japanese Patent Application Publication No. 2005-105053 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, optimizing air conditioning capacity in various indoor spaces requires time and cost in design, and sometimes the desired effect cannot be achieved due to environmental and equipment constraints. Furthermore, as in Patent Document 1, large-scale construction of existing ceilings is required to apply anti-mold gypsum board to ceiling materials, increasing costs. Moreover, as in Patent Document 2, the effectiveness of functional coatings utilizing photocatalysts in dark areas is limited. For existing ceilings, walls, or other surfaces, it is necessary to suppress condensation, dirt, and the mold that arises from them.

[0010] This disclosure was made to solve the above-mentioned problems, and aims to provide a coating composition, a coating film, and a method for manufacturing a coating film that can inhibit condensation, dirt, and mold growth caused by them on existing ceilings, walls, or other items.

[0011] Methods for solving problems

[0012] The coating composition disclosed herein includes: irregularly shaped silica particles having an average particle size of 12 nm to 250 nm; hydrophobic resin particles having an average particle size of 50 nm to 500 nm; and water-insoluble antifungal particles having a rod-like, needle-like, or fibrous crystalline structure with a crystal length of 1 μm or more and 10 mm or less and a crystal size of 0.1 μm or more and 15 μm or less. The mixture of the irregularly shaped silica particles, the hydrophobic resin particles, water, and the antifungal particles is alkaline with a pH of 9 to 11.

[0013] The effects of the invention

[0014] According to this disclosure, condensation, dirt, and mold growth caused by them can be inhibited on existing ceilings, walls, or other surfaces. This allows for the maintenance of cleanliness. Attached Figure Description

[0015] Figure 1 This is a cross-sectional schematic diagram illustrating the coating film according to Embodiment 1.

[0016] Figure 2 This is a schematic diagram illustrating the chain-like irregularly shaped silica particles involved in Embodiment 1.

[0017] Figure 3 This is a schematic diagram illustrating the bead-shaped irregular silica particles involved in Embodiment 1. Detailed Implementation

[0018] The following description of embodiments of the coating composition, coating film, and method for manufacturing the coating film of this disclosure is based on the accompanying drawings. It should be noted that this disclosure is not limited to the embodiments described below. Furthermore, the size relationships of the constituent components in the drawings may sometimes differ from their actual relationships. Additionally, in the following description, to facilitate understanding of this disclosure, appropriate terms indicating direction are used for illustrative purposes; these terms do not limit the scope of this disclosure. Examples of terms indicating direction include, for instance, "up," "down," "right," "left," "front," or "back."

[0019] Implementation method 1.

[0020] Figure 1 This is a cross-sectional schematic diagram showing the coated film 5 according to Embodiment 1. Figure 1 As shown, the coating film 5 is formed by coating a coating composition containing an aqueous mixture of irregularly shaped silica particles 2, hydrophobic resin particles 3, and anti-mildew particles 4 onto a substrate 1.

[0021] In indoor spaces, for example, the cold radiation from freezers or refrigerators can sometimes cool the ceilings or walls surrounding them. Combined with warm air flowing in from outside, this can easily lead to condensation. Additionally, it's common to see condensation or blackened dirt on ceilings or walls near air conditioner vents. This is because mold easily grows in such places, using the moisture from the condensation or dirt as nutrients. Mold growth requires spores, water, nutrients, oxygen, and temperature. In typical indoor spaces, oxygen and temperature provide sufficient conditions for mold growth. Furthermore, mold spores typically reproduce in soil and plants, and are released into the air. In indoor spaces, mold spores can float in any space as people or objects enter and exit. Therefore, to inhibit mold growth, it's necessary to reduce both water and nutrients, and to inhibit the attachment of mold spores and the growth of mold hyphae.

[0022] (Substrate 1)

[0023] Substrate 1 is, for example, a ceiling material or wall material that is absorbent.

[0024] (Irregularly shaped silica particles 2)

[0025] Figure 2 This is a schematic diagram illustrating the chain-like irregularly shaped silica particles 2 involved in Embodiment 1. Figure 3 This is a schematic diagram illustrating the beaded, irregularly shaped silica particles 2 according to Embodiment 1. The irregularly shaped silica particles 2 have irregular shapes such as needle-like, scale-like, chain-like, or beaded. The irregularly shaped silica particles 2 are a product of generally spherical particles with a particle size of 5 nm to 20 nm. It will be noted that the irregularly shaped silica particles 2 are preferably in a chain-like or beaded configuration with an average particle size of 12 nm to 250 nm. Figure 2 The chain-like irregularly shaped silica particles 2 shown in the figure and Figure 3 The beaded irregular silica particles 2 shown are an example; some may be linked together in a chain or beaded manner. Furthermore, regarding the irregular silica particles 2, generally spherical particles may be mixed, as well as chain-like, beaded, or scale-like particles.

[0026] It should be noted that the average particle size is determined by dynamic light scattering or laser diffraction of the aqueous dispersion of silica particles before mixing with the coating composition, or by other methods. In the coating composition, the average particle size can be larger due to the aggregation of silica particles.

[0027] Shaped silica particles 2 are the main component of the coating film 5 and act as a binder to fix the hydrophobic resin particles 3 and the antifungal particles 4. By using chain-like or beaded shaped silica particles 2, the flowability of the coating composition during coating and drying can be preferably controlled. In the case of coating on uneven surfaces, if the coating composition is based on spherical silica, the coating film 5 obtained after coating and drying will not form a sufficient film on the convex surfaces because liquid only accumulates in the concave areas. In addition, in the case of a coating composition based on spherical silica on a substrate 1 with water absorption or a porous substrate 1, due to capillary action, water in the coating composition moves into the interior of the substrate 1, and a good coating film 5 cannot be formed. In contrast, the shaped silica particles 2 of this embodiment 1 are difficult to pass through the fine pores of the substrate 1 due to their size, and a film can be formed on the surface of the substrate 1.

[0028] In a coating composition containing irregularly shaped silica particles 2 linked in a chain-like or beaded manner, the coating film 5 obtained by coating and drying the substrate 1 has fine pores within the film. The irregularly shaped silica particles 2 are the main component making the coating film 5 hydrophilic; by forming fine pores, they achieve high hydrophilicity compared to the use of spherical silica. Furthermore, the hydrophilicity of the irregularly shaped silica particles 2 is difficult to reduce even in cases of contamination caused by the adsorption of hydrophobic substances. Additionally, even in cases of dust-related contamination, the intermolecular forces (adhesion) of the irregularly shaped silica particles 2 are reduced due to the pores, thus making it difficult for dust to adhere.

[0029] By using irregularly shaped silica particles 2, compared to using spherical silica, defects such as cracks are less likely to form in the coating film 5. As a result, the coating film 5 is difficult to peel off, and degradation caused by friction or environmental changes is suppressed, resulting in a long lifespan and high durability. Furthermore, since there are no cracks where dust adheres, dust contamination is also minimized.

[0030] In the coating composition, silica particles are used as a basic component. Silica particles have a lower refractive index than other hydrophilic inorganic particles such as titanium dioxide or alumina particles, thus reducing the likelihood of turbidity caused by light scattering at interfaces or surfaces. In this embodiment 1, by using irregularly shaped silica particles 2 as the silica particles, the coating film 5 has fine pores. This results in a lower refractive index. Furthermore, the formation of cracks that cause light scattering is suppressed, thereby reducing turbidity.

[0031] When the average particle size of the irregularly shaped silica particles 2 is less than 12 nm, it is not possible to fully obtain the effects of coating properties, low turbidity, and low contamination on uneven or absorbent surfaces. When the average particle size exceeds 250 nm, the resulting coating film 5 becomes brittle, the micropores in the film become excessively large, and it becomes prone to turbidity, so it is not preferred.

[0032] The content of the irregularly shaped silica particles 2 in the coating composition is not particularly limited, but is preferably 0.1 wt% or more and 15 wt% or less. More preferably, it is 0.5 wt% or more and 10 wt% or less. If the content of the irregularly shaped silica particles 2 is too low, the substrate 1 cannot be adequately covered by the coating film 5. On the other hand, if the content of the irregularly shaped silica particles 2 is too high, the formed film becomes excessively thick and becomes prone to whitening or peeling.

[0033] Generally, when silica particles are stably dispersed in water, their stability is influenced by pH. Silica particles exhibit high stability in the acidic region of pH 2–4 and the alkaline region of pH 8–11. In alkaline conditions exceeding pH 9, the dissolved silica component acts as a binder between silica particles during drying, thus readily achieving film strength, which is preferable. In the coating composition of Embodiment 1, pH 8–12 is preferred, and pH 9–11 is more preferable.

[0034] Since the coating composition is alkaline, it is preferable to use an alkaline aqueous dispersion of silica as the silica particles. A water-soluble alkaline component is added as needed to adjust the pH. Sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium silicate, or lithium silicate can be used as the water-soluble alkaline component. When adding an alkaline component, it is preferable that the silica particles are 2% or more and 50% or less by mass, more preferably 5% or more and 25% or less by mass. If the amount of water-soluble alkaline component added is excessively increased, the effects of low turbidity and low contamination obtained by adding the irregularly shaped silica particles 2 may not be sufficiently achieved.

[0035] In the addition of water-soluble alkaline components, sodium silicate and lithium silicate, in particular, function as binders for silica particles. In this case, the coating film 5 achieves high strength, and also improves water resistance, making it preferable. Furthermore, in this case, sodium silicate contains Na₂O… In nSiO2, n is preferably 2 or more and 4 or less. In lithium silicate, in Li2O... In nSiO2, n is preferably 5 or more and 8 or less. When n is small, that is, when there is less SiO2, the effect of adjusting alkalinity can still be obtained, but the effect of increasing the strength of the coating film 5 cannot be obtained. When n is large, that is, when there is more SiO2, sometimes it is not possible to fully obtain the effects of low turbidity and low contamination obtained by adding irregularly shaped silica particles 2.

[0036] pH is also related to the inhibitory effect on mold. Although mold grows readily in pH 2–8.5, its growth is limited in alkaline environments above pH 9. In the coated film 5 obtained using a coating composition with pH 8–12, the product contains alkaline components. In conditions where mold growth is facilitated by condensation or other factors, the alkaline components dissolve and alkalize the film, thus inhibiting mold growth.

[0037] (Hydrophobic resin particles 3)

[0038] The hydrophobic resin particles 3 are particles of a resin that have low affinity for water and are difficult to dissolve in water. Examples of hydrophobic resin particles 3 include silicone resin particles or fluoropolymer particles, but they are not limited to these and can be other resins. It should be noted that fluoropolymer particles are preferred as the resin dispersed in an aqueous medium. Specific examples of fluoropolymer particles include PTFE (polytetrafluoroethylene) and FEP (tetrafluoroethylene). Hexafluoropropylene copolymer), PFA (tetrafluoroethylene) Perfluoroalkyl vinyl ether copolymers), ETFE (ethylene) Tetrafluoroethylene copolymer), ECTFE (ethylene) The fluoropolymers include copolymers of polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyvinylidene fluoride (PCTFE), polyvinyl chloride (PVF), and polyvinyl fluoride (PVF), as well as copolymers and mixtures thereof, and products in which other resins are mixed into these fluoropolymers. Among these, PTFE (polytetrafluoroethylene) and FEP (polytetrafluoroethylene), which have excellent stability and high hydrophobicity, are preferred as hydrophobic resin particles 3. (Hexafluoropropylene copolymer).

[0039] There is no particular limitation on the average particle size of the hydrophobic resin particles 3, but when measured by light scattering, it is preferably 50 nm to 500 nm, more preferably 100 nm to 250 nm. By including hydrophobic resin particles 3 with an average particle size within this range in the coating composition, the hydrophobic resin particles 3 are adequately dispersed in the coating film 5 and become easily exposed on the surface of the coating film 5, thus obtaining good antifouling performance. If the average particle size of the hydrophobic resin particles 3 is less than 50 nm, the hydrophobic resin particles 3 are difficult to expose on the surface of the coating film 5, and sometimes the desired antifouling performance is not obtained. On the other hand, if the average particle size of the hydrophobic resin particles 3 exceeds 500 nm, the area of ​​the hydrophobic portion in the resulting coating film 5 becomes larger, or the unevenness of the coating film 5 becomes larger, and therefore sometimes the desired antifouling performance is not obtained.

[0040] The weight ratio of the irregularly shaped silica particles 2 to the hydrophobic resin particles 3 in the coating composition is 70:30 to 95:5, preferably 75:25 to 90:10. Within this weight ratio range, a coating film 5 is obtained in which the hydrophilic portion of the irregularly shaped silica particles 2 and the hydrophobic portion of the hydrophobic resin particles 3 are evenly mixed. At this time, the coating film 5 obtained by drying at room temperature exhibits good antifouling properties. The hydrophilic portion of the surface of the coating film 5 plays an important role in improving the antifouling properties. Furthermore, if the weight ratio is within this range, the hydrophilic portion is continuous on the surface of the coating film 5 without being divided by the hydrophobic portion. Therefore, even when water droplets or the like adhere to the surface of the coating film 5, water easily spreads throughout the entire coating film 5.

[0041] Furthermore, water imparts the effect of lifting and removing hydrophilic and hydrophobic dirt adhering to the surface of the coating film 5, or making it difficult for it to adhere. In particular, during condensation, rainfall, and washing, the adhering dirt is easily removed from the surface of the coating film 5. In addition, since the coating film 5 is mainly composed of a continuous silica film, it is also able to suppress the charging of the film surface, which is the cause of dirt adsorption. Furthermore, the coating film 5 has the characteristic of easy water spread. Therefore, even if condensation occurs, the condensate spreads on the coating film 5, and thus the condensate dries easily. In the coating film 5, dirt is difficult to adhere to, condensate spreads easily, and dries easily, thus creating an environment where mold that feeds on dust and water is difficult to proliferate.

[0042] Regarding airborne mold, there exists mold that floats as individual mold spores, and mold that floats mixed with and in contact with both hydrophilic and hydrophobic dirt as mold spores or hyphae. Generally, mold spores have a hydrophilic surface and attach through electrostatic bonding between hydrophilic groups, liquid bridging generated by water, or intermolecular forces. Mold spores are tiny particles with a diameter of 2 μm to 10 μm. To prevent the attachment of mold spores, it is sufficient to form a coating film 5 with a hydrophilic portion that is small enough for non-hydrophilic dirt to adhere to.

[0043] Generally, mold hyphae have a length of tens of μm to several millimeters. Therefore, the hydrophilic and hydrophobic dirt mixed with mold has a size of tens of μm to several millimeters. In order to prevent the adhesion of hydrophilic dirt mixed with mold, it is necessary to form a non-hydrophilic coating film 5 with a hydrophilic portion that is small enough for non-hydrophobic dirt to adhere to. Similarly, in order to prevent the adhesion of hydrophobic dirt mixed with mold, it is necessary to form a non-hydrophobic coating film 5 with a hydrophobic portion that is small enough for non-hydrophobic dirt to adhere to. In this embodiment 1, by making the mass ratio of irregularly shaped silica particles 2 to hydrophobic resin particles 3 the above-mentioned mass ratio, the hydrophobic resin particles 3 are appropriately dispersed in the hydrophilic silica film. As a result, even if hydrophilic dirt adheres to the hydrophilic portion, the hydrophilic dirt becomes difficult to adhere due to the physical distance caused by the surface of the hydrophobic portion close to the hydrophilic portion or the protrusion of the hydrophobic portion. Similarly, by utilizing the hydrophilic portion of the coating film 5, the adhesion of hydrophobic dirt can be inhibited.

[0044] It should be noted that, for the hydrophobic resin particles 3, commercially available products that have been pre-dispersed in water can be used. In this case, to make the coating composition alkaline, a neutral or alkaline dispersion is preferred.

[0045] (Anti-mold particles 4)

[0046] The anti-mold particles 4 are preferably poorly soluble in water. Therefore, the anti-mold particles 4 can be present on the surface of the absorbent substrate 1. Thus, a coating film 5 that is difficult for mold to grow can be obtained. As the poorly soluble anti-mold particles 4, benzimidazole-based or iodine-based anti-mold agents are preferred, but there are no particular limitations. Examples of anti-mold particles 4 include thiabendazole (TBZ), befentin (BCM), 3-iodo-2-propyl-N-butylcarbamate (IPBC), and diiodomethyl-p-tolyl sulfone (DMTS). Regarding solubility in water, TBZ is 0.003%, IPBC is 0.0156%, DMTS is 0.1%, and BCM is insoluble, all showing poor solubility in water. By dispersing the anti-mold particles in the coating composition without dissolving them, the anti-mold particles 4 can be present within the coating film 5, thus inhibiting mold growth.

[0047] Regarding the water-insoluble antifungal particles 4, a crystalline antifungal agent in the form of micro-powder, rod, needle, or fibrous material is used. Rod, needle, or fibrous forms are particularly preferred as the crystalline form of the antifungal agent. When the antifungal particles 4 are rod-shaped crystals, the ratio of the minor axis to the major axis is preferably 1.2 or more. In the coating composition or coating film 5, the length of the antifungal particles 4 crystals is preferably 1 μm or more and 10 mm or less, and the crystal size is 0.1 μm or more and 15 μm or less.

[0048] The coating composition containing anti-mold particles 4, even when coated on a porous, uneven substrate 1, results in a state where the anti-mold agent does not penetrate into the interior or recesses of the substrate 1 but accumulates on the surface, thus achieving high anti-mold properties. Furthermore, in the coating film 5, it is arranged along the surface of the substrate 1 in the longitudinal direction. Therefore, the anti-mold particles 4 are unlikely to protrude from the surface of the coating film 5, making it difficult to increase the unevenness of the coating film 5's thickness or to cause cracks. Generally, if the surface unevenness of the coating film 5 increases, the anti-fouling properties of the coating film 5 will be compromised. In contrast, this embodiment 1, by adopting the above-described form of anti-mold agent addition, allows for the addition of a large amount of anti-mold agent without compromising anti-fouling properties.

[0049] The coating film 5 containing such anti-mold particles 4 is achieved by using the aforementioned irregularly shaped silica particles as silica particles in the coating composition. By using irregularly shaped silica particles 2 as a base, the coating composition exhibits the flowability of a pseudoplastic fluid. Furthermore, it is easily configured so that the anti-mold particles 4 are aligned longitudinally along the surface of the substrate 1, and even with the anti-mold particles 4 present, localized thickening is not easily observed. Therefore, a highly uniform coating film 5 can be formed. In addition, since the irregularly shaped silica particles 2 form a film with fine pores, cracks are not generated, and the anti-mold particles 4 can be encapsulated. Furthermore, when the coating film 5 is in a humidified state, the anti-mold agent can diffuse through the pores.

[0050] Even when the antifungal agent particles are in granular or powder form, they can be contained in the coating film 5. However, when the particles are granular, i.e., with a particle size exceeding 3 μm, the particles tend to be misaligned during the coating process of the coating composition, making it difficult to form a uniform coating film 5 with antifouling properties. Furthermore, in the case of fine particles, even if a uniform coating film 5 is formed, if the total addition amount of the antifungal agent relative to the irregular silica particles 2 and the hydrophobic resin particles 3 exceeds 5%, a continuous silica phase is not formed. Therefore, the strength of the coating film 5 is reduced, and problems such as wear or peeling are prone to occur.

[0051] The content of the water-insoluble anti-mildew particles 4 is preferably 5 wt% or more and 500 wt% or less relative to the total of the shaped silica particles 2 and the hydrophobic resin particles 3. More preferably, the content of the water-insoluble anti-mildew particles 4 is 5 wt% or more and 150 wt% or less. If the content of the anti-mildew particles 4 is too low, it may be difficult for the coating film 5 to have sufficient anti-mildew properties. In addition, if there are too many anti-mildew particles 4, the antifouling properties of the coating film 5 may be impaired.

[0052] In addition to the poorly water-soluble anti-mold particles 4, a water-soluble anti-mold agent may be included. Unlike the poorly water-soluble anti-mold particles 4, the water-soluble anti-mold agent is less likely to remain on the surface of the absorbent or porous substrate 1 and instead penetrate into the interior of the substrate 1. Therefore, when condensation occurs on the surface of the substrate 1, the condensed water seeps into the interior and onto the surface of the substrate 1. This inhibits mold growth.

[0053] From the viewpoint of imparting various properties to the coating composition, the coating composition can contain known components within the scope of not hindering the effects obtained in Embodiment 1. Examples of known components include surfactants, coupling agents, or silane compounds. The amount of these components is not particularly limited as long as it does not hinder the effects obtained in Embodiment 1, and can be appropriately adjusted according to the type of component used.

[0054] (Method for manufacturing coating 5)

[0055] The coating composition is prepared by mixing water, shaped silica particles 2, hydrophobic resin particles 3, and antifungal particles 4. There are no particular limitations on the coating film 5, and it can be formed using conventionally known methods. Examples include spraying, brush coating, roller coating, or dip coating. These coating methods can be combined. After the coating composition is applied to the substrate 1, it becomes the coating film 5 simply by natural drying. Due to partial dissolution on the surface of the shaped silica particles 2 contained in the coating composition, the silica particles condense between each other during natural drying, thus forming the coating film 5. The coating film 5 can also be obtained by accelerating drying using airflow, warm air, etc.

[0056] The coating film 5 is mainly composed of a continuous silica film. Therefore, it possesses the characteristics of an electrically charged film surface that inhibits the adsorption of dirt and facilitates the spread of water. Thus, even if condensation occurs, the condensate spreads along the coating film 5, making it easy to dry. Furthermore, the condensate is alkaline, making it difficult for mold to proliferate. Moreover, the presence of water-insoluble anti-mold particles 4 further inhibits mold growth. Thus, in the coating film 5 of Embodiment 1, dirt is difficult to adhere to, condensate spreads easily, and drying is quick. Therefore, a film that makes it difficult for mold, which uses dust and water as bait, to proliferate is obtained.

[0057] Example

[0058] The following examples and comparative examples illustrate the implementation in detail, but the implementation is not limited to the examples described below.

[0059] As the irregularly shaped silica particles 2, colloidal silica (Cataloy S-30L, Nichii Catalyst Chemical Co., Ltd.) with a particle size of 10nm to 25nm was used. As the hydrophobic resin particles 3, Algoflun D PTFE dispersion (manufactured by Solbes Petroleum Polymers Japan Co., Ltd.) was used. As the poorly water-soluble antifungal agent, a 5% ethanol solution of IPBC was used. The coating composition was formed by adding hydrophobic microparticles and irregularly shaped silica particles 2 while stirring to deionize water. Then, the pH was adjusted by adding an alkaline aqueous solution. Finally, after standing, an ethanol solution of the poorly water-soluble antifungal agent was added dropwise. For coating, apply the coating to the decorative gypsum board (Jiputon Light, Yoshino Gypsum Co., Ltd.) using a spatula brush and allow it to dry naturally. The coating amount is set at 30 g / m². 2 .

[0060] The evaluation of stain resistance was conducted using the following method. The substrate 1 with the coated film 5 was placed horizontally, and a simulated dirt mixture of Kanto rohm dust and carbon black in a 1:1 ratio was placed on the coated film 5 through a stainless steel sieve, covering the entire surface. Then, the substrate 1 was vertically erected to remove excess simulated dirt. The simulated dirt remaining on the coated film 5 was visually evaluated using a 6-level scale, with a case of extremely black dirt designated as 0 and a case of almost no dirt designated as 5. The evaluation of mildew resistance was conducted using the following method. The substrate 1 with the coated film 5 was cut into 5cm squares, and an aqueous dispersion of spores collected from indoor mold was sprayed onto each square. The test piece was placed in a constant temperature and high humidity environment of approximately 30°C and 80% humidity, and mold growth was visually confirmed. Mold resistance was compared based on the number of days until mold growth.

[0061] Table 1 summarizes the results of Examples 1-5 and Comparative Examples 1-4. Coating compositions with different wt% of shaped silica particles 2, wt% of hydrophobic resin particles 3, wt% of poorly water-soluble antifungal particles 4, and different types and amounts of water-soluble alkali were evaluated.

[0062] [Table 1]

[0063]

[0064] The value represents the concentration in the coating composition, in wt%.

[0065] pH is the value of the coating composition.

[0066] ※: Sodium silicate with a molar ratio of Na2O:SiO2 of 3

[0067] ※※: Use neutral silica

[0068] Examples 1-5 all exhibited high stain resistance, showing excellent anti-mold properties for more than 12 days until mold growth. This demonstrates that higher pH values ​​correlate with higher anti-mold properties. That is, it is known that by appropriately adding a water-soluble alkali to increase the pH, anti-mold properties can be improved without compromising stain resistance. Comparative Example 1 did not achieve stain resistance because it lacked the addition of hydrophobic resin particles 3. Comparative Example 2 did not achieve stain resistance because it lacked the addition of shaped silica particles 2. Comparative Example 3 exhibited low anti-mold properties due to its low pH. Comparative Example 4, due to its excessive alkali content, showed good anti-mold properties but lacked stain resistance.

[0069] Thus, according to Embodiment 1, condensation, dirt, and mold growth caused by these factors can be suppressed on existing ceilings, walls, or other surfaces. This allows for the maintenance of cleanliness.

[0070] Explanation of reference numerals in the attached figures

[0071] 1. Substrate, 2. Irregularly shaped silica particles, 3. Hydrophobic resin particles, 4. Anti-mildew particles, 5. Coating film.

Claims

1. A coating composition comprising: The formulation includes: irregularly shaped silica particles with an average particle size of 12 nm to 250 nm; hydrophobic resin particles with an average particle size of 50 nm to 500 nm; and water-insoluble antifungal particles that are rod-shaped, needle-shaped, or fibrous, with a crystal length of 1 μm or more and 10 mm or less, and a crystal size of 0.1 μm or more and 15 μm or less. The mixture of the irregularly shaped silica particles, the hydrophobic resin particles, water, and the antifungal particles is alkaline with a pH of 9-11.

2. The coating composition according to claim 1, wherein, The irregularly shaped silica particles are in the form of chains or beads.

3. The coating composition according to claim 1 or 2, wherein, The weight ratio of the irregularly shaped silica particles to the hydrophobic resin particles is 70:30 to 95:

5.

4. The coating composition according to any one of claims 1 to 3, wherein, The irregularly shaped silica particles constitute a proportion of 0.1 wt% to 15 wt% in the mixture.

5. The coating composition according to any one of claims 1 to 4, comprising sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium silicate, or lithium silicate.

6. The coating composition according to any one of claims 1 to 5, wherein, The hydrophobic resin particles are fluororesins.

7. The coating composition according to any one of claims 1 to 6, wherein, The antifungal particles include benzimidazole-based or iodine-based antifungal agents with a solubility of less than 0.1% in water.

8. The coating composition according to any one of claims 1 to 6, wherein, The antifungal particles are IPBC.

9. The coating composition according to any one of claims 1 to 8, further comprising a water-soluble antifungal agent.

10. The coating composition according to any one of claims 1 to 9, wherein, The antifungal particles have rod-shaped crystals with a minor axis to major axis ratio of 1.2 or higher.

11. A coating film, comprising: Irregularly shaped silica particles with an average particle size of 12 nm to 250 nm; hydrophobic resin particles with an average particle size of 50 nm to 500 nm. Water-insoluble antifungal particles that are crystalline in the form of rods, needles, or fibers, with a crystal length of 1 μm or more and 10 mm or less, and a crystal size of 0.1 μm or more and 15 μm or less.

12. The coating film according to claim 11, wherein, The attached water appears alkaline.

13. A method for manufacturing a coated film, comprising: The process of applying the coating composition to a substrate; and the process of natural drying or warm air drying. The coating composition contains: irregularly shaped silica particles having an average particle size of 12 nm to 250 nm; hydrophobic resin particles having an average particle size of 50 nm to 500 nm; water-insoluble antifungal particles having a rod-shaped, needle-shaped, or fibrous crystalline structure with a crystal length of 1 μm or more and 10 mm or less and a crystal size of 0.1 μm or more and 15 μm or less; and water.

14. The method for manufacturing a coated film according to claim 13, wherein, The substrate is a ceiling or wall material that is absorbent.

15. The method for manufacturing a coated film according to claim 13 or 14, comprising the step of applying the coating composition onto the substrate using a brush or roller.

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