JP5581266B2 - Paint and air conditioner - Google Patents

Description

  The present invention relates to a paint for suppressing adhesion of dust to a resin surface and an air conditioner including a blower fan to which the paint is applied.

  An air conditioner circulates indoor air in a heat exchanger to produce heated, cooled, and dehumidified air (conditioned air), and blows the air into the room to air condition the room.

  A blower fan that circulates room air accumulates dust contained in the room air due to long-term use, resulting in an increase in noise of the blower fan and a reduction in blowing performance. Further, the blower fan becomes dirty due to the proliferation of bacteria, molds, etc. contained in the dust. Bacteria such as mold are also contained in the dust, these multiply and diffuse the spores into the room by blowing air. However, the blower fan is attached with a structure that is difficult to reach for the safety of the user, and it is very difficult to remove the blower fan and clean the attached dirt.

  On the other hand, in order to keep the blower fan clean and maintain the blower performance, the blower fan is coated with a hydrophilic / hydrophobic coating material containing silica fine particles and fluorine fine particles to prevent dust from adhering to the blower fan. There is an air conditioner that is suppressed (see, for example, Patent Document 1).

JP 2008-292069 A

  Dust adheres to the blower fan mainly due to the following reasons. That is, in the heating operation in winter, the blower fan is charged and dust adheres due to static electricity generated by friction between the indoor circulating air and the blower fan. Moreover, in the cooling operation in summer, the inside of the air conditioner becomes a high humidity environment, and water droplets adhere to the blower fan and dust adheres thereto.

In order to prevent charging of the blower fan, it is effective to lower the surface resistance value to about 10 ¹⁰ Ω, which is considered to be that the resin is not charged. It is also effective to quickly dry and remove moisture adhering to the blower fan. However, in Patent Document 1, since the fluororesin particles are hydrophobic and have a surface resistance value as high as about 10 ¹⁸ Ω, the surface of the blower fan is easily charged, so that dust easily adheres to and accumulates on the blower fan. Become.

  Furthermore, when the surface of the blower fan becomes hydrophobic, the surface energy decreases. Therefore, if the inside of the air conditioner is in a high humidity environment during cooling operation, water droplets (polka dots) attached to the blower fan will easily leave the blower fan surface, jump out into the indoor space, and soil the floor around the air conditioner. There is a fear. Moreover, in patent document 1, although the average particle diameter of fluororesin microparticles | fine-particles is 50-500 nm, since a particle diameter is large, there exists a possibility that a coating film may become cloudy and, as a result, there exists a possibility of impairing the external appearance of a ventilation fan.

  An object of the present invention is to provide a paint that suppresses adhesion of dust to the resin surface, and an air conditioner including a blower fan to which the paint is applied.

In order to solve the above-described problems, an air conditioner of the present invention includes a heat exchanger and a blower fan that causes air to flow through the heat exchanger, and a hydrophilic film having antibacterial properties is formed on the resin surface of the blower fan by a paint. The paint has a silicon compound having a hydrolyzable residue, silicon oxide particles , alcohol and an organic solvent having a cyclic ether structure, the organic solvent having a cyclic ether structure is tetrahydrofuran, and the addition amount of tetrahydrofuran is 20 to 40 wt. % .

  ADVANTAGE OF THE INVENTION According to this invention, an air conditioner provided with the coating material which suppresses adhesion of the dust to the resin surface, and the ventilation fan with which the coating material was apply | coated can be provided.

The block diagram of an air conditioner. The sectional side view of an indoor unit. The whole figure of a ventilation fan. A cross-sectional photograph of an antibacterial hydrophilic film. The blower fan has a cross section. Dust adhesion test results for the blower fan. Antibacterial test results of the blower fan.

  The coating material of the present invention for forming a hydrophilic film having antibacterial properties on the surface of the resin will be described below. The paint of the present invention has a silicon compound having a hydrolyzable residue, silicon oxide particles, alcohol, an organic solvent having a cyclic ether structure, and a colloid composed of inorganic oxide particles containing silver.

  The silicon compound having a hydrolyzable residue functions as a film binder. The silicon oxide particles increase the surface area of the film by forming irregularities on the surface or forming voids inside. An alcohol and an organic solvent having a cyclic ether structure function as a solvent. A colloid composed of inorganic oxide particles containing silver functions as an antibacterial agent. Hereinafter, each composition of the paint of the present invention will be described.

(1) Silicon compound having a hydrolyzable residue As described above, a silicon compound having a hydrolyzable residue forms a silicon-oxygen bond between molecules when the hydrolyzable residue is hydrolyzed, Functions as a binder. A trialkoxysilane residue or a trichlorosilane residue can be used as the hydrolyzable residue.

  Silica sol can be used as the silicon compound having an alkoxysilane residue. Silcasol is a compound in which alkoxysilane such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetraisobutoxysilane, tetrabutoxysilane, etc. is polymerized to a molecular weight of about several thousand and is soluble in alcoholic solvents. It is. By heating these compounds, a silicon oxide binder can be formed. The number of carbon atoms of the alkoxy group of the alkoxysilane residue is preferably 1 to 4 in consideration of reactivity. If it exceeds this range, the reactivity is lowered, and film formation takes several hours to several days.

  As silicon compounds having other hydrolyzable residues, compounds having an amino group, a chloro group, a mercapto group, or the like can be used. Specifically, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropylmethyl Dimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, etc. Is mentioned. When these compounds having an amino group, a chloro group, a mercapto group or the like are used, the dispersibility of the silicon oxide particles can be improved.

  On the other hand, in order to increase the strength of the film, silica sol is preferable to a compound having an amino group, chloro group, mercapto group or the like. This is because the ratio of silicon-oxygen bonds increases, that is, the crosslink density of the film increases.

  If the thickness of the film is too thin, the holding power of the silicon oxide particles becomes weak, so at least 30 nm is necessary. However, if it is too thick, specifically, if it is 400 nm or more, there is a risk that the film may crack at low or high temperatures due to the effect of the difference in linear expansion coefficient between the formed film and the resin substrate. Therefore, the film thickness is preferably 30 to 400 nm, and more preferably 50 to 300 nm with a margin.

(2) Silicon oxide particles The silicon oxide particles increase the surface area of the film by forming irregularities on the surface or forming voids inside. When the average particle diameter of silicon oxide is 100 nm or more as measured by the dynamic light scattering method, the formed hydrophilic film becomes cloudy and impairs the design. Therefore, the average particle diameter of the silicon oxide particles is preferably 100 nm or less as measured by the dynamic light scattering method. On the other hand, when the particle becomes smaller, the bulk specific gravity becomes smaller, and particularly when the particle size becomes less than 10 nm as measured by the dynamic light scattering method, the bulk specific gravity rapidly decreases with respect to the particle diameter. If the bulk specific gravity is small, it tends to float in the air, so local exhaust equipment is required when working with paint preparation. However, when the local exhaust system is operated, if the average particle diameter is less than 10 nm as measured by the dynamic light scattering method, the ratio of floating in the air increases, so that the weighing may become inaccurate. Therefore, the average particle diameter of silicon oxide is preferably 10 to 100 nm as measured by a dynamic light scattering method.

  The shape of the particles may be either spherical or irregular. The hydrophilicity is improved by increasing the surface area. In order to increase the surface area, it is desirable that the arithmetic average roughness of the film surface is large. In order to reduce the contact angle with water to 10 ° or less, at least the arithmetic average roughness of the film surface needs to be 2 nm or more. However, if the arithmetic average roughness of the film surface is too large, dirt such as dust tends to adhere. As a result of experiments by the inventors, when the arithmetic average roughness of the film surface exceeds 30 nm, dust tends to adhere. From the above, the arithmetic average roughness of the film surface is preferably 2 to 30 nm.

(3) Alcohol An alcohol and an organic solvent having a cyclic ether structure described later are paint solvents. Considering application to the resin surface by spraying or dipping, the boiling point is preferably about 100 to 120 ° C. As the alcohol having a boiling point in this range, normal butanol having a boiling point of 118 ° C. can be used.

  When the silicon compound having a hydrolyzable residue has an alkoxysilane residue, the alkoxysilane residue is hydrolyzed in the paint, and alcohol having 1 to 4 carbon atoms, that is, methanol, ethanol, normal propanol, 2- Propanol, normal butanol, 2-butanol, and tert-butanol are generated. Therefore, these alcohols are also slightly mixed in the paint. However, when applied by spraying or dip coating, the proportion of the solvent in the paint is much larger than that of the binder, so that butanol as a whole is the mixed alcohol.

(4) Organic solvent having a cyclic ether structure An organic solvent having a cyclic ether structure is a solvent for paints as well as alcohol. An organic solvent having a cyclic ether structure can dissolve most linear thermoplastic resins such as acrylic and polycarbonate. Further, even a resin that does not dissolve tends to swell upon contact. Therefore, in the present invention, a mixed solvent obtained by mixing an alcohol and an organic solvent having a cyclic ether structure is used. For example, when the coating material of the present invention touches the surface of a linear thermoplastic resin such as an acrylic resin or a polycarbonate resin, the surface slightly dissolves to form fine irregularities. Many of the other resins swell even if not dissolved, and at that time, irregularities are formed on the surface. The paint penetrates into the irregularities and hardens. After film formation, the physical strength of the film is enhanced by the anchoring effect of the part of the film that enters the irregularities.

  Examples of the organic solvent having a cyclic ether structure, that is, an organic compound having a cyclic ether structure that is liquid at room temperature include epichlorohydrin, epibromohydrin, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxydodecane, 1,2-epoxycyclopentane, 1,2-epoxycyclohexane, 1,2-epoxycyclooctane, 1,2-epoxycyclodecane, 1,2-epoxy Compounds having a glycidyl group such as cyclododecane, 1,4-epoxycyclohexane, 1,4-epoxycyclooctane, 1,4-epoxycyclodecane, 1,4-epoxycyclododecane, 1,3-dioxolane, 2,2 -Oxolane compounds such as dimethyl-1,3-dioxolane, 1,4- Dioxane, 2,4-dimethyl-1,3-dioxane compounds such as dioxane, tetrahydrofuran, tetrahydrofuran-based compounds such as 2,5-dimethyl tetrahydrofuran.

  Among these, a compound having a glycidyl group may react with a hydroxyl group generated by the ring opening of the glycidyl group and decomposition of the alkoxysilane group at a high temperature. If this reaction proceeds, the film strength may decrease. Since oxolane-based compounds are likely to generate peroxides, care must be taken when storing paints, for example, by adding an antioxidant such as dibutylhydroxytoluene or avoiding impact. Considering these, dioxane compounds and tetrahydrofuran compounds are preferred. Furthermore, 1,4-dioxane and tetrahydrofuran, which are general-purpose organic solvents, are more preferable in that the raw material cost of the paint can be reduced.

  When the adhesion of the film was examined, high adhesion was obtained when the coating content of the organic solvent having a cyclic ether structure in the coating was 20 to 40% by weight. When it exceeds 40% by weight, the resin surface is slightly dissolved or swollen, the surface irregularities become too large, the flatness is lowered, and the design tends to be lowered such that the surface becomes cloudy. If it was less than 20% by weight, the improvement in adhesion could not be confirmed predominantly. Therefore, the coating content of the organic solvent having a cyclic ether structure in the coating is preferably 20 to 40% by weight.

  On the other hand, the inventor also examined the ratio of the solvent (an alcohol and an organic solvent having a cyclic ether structure) in the paint of the present invention. In the coating material of the present invention, a uniform thin film having a thickness of about 50 to 300 nm could be formed by applying by spraying or dipping. However, when there was too little solvent in the paint, the nozzle was likely to be clogged by spraying, and the flatness of the film was lowered by dipping. This is because the silicon compound having a hydrolyzable group used as a binder tends to harden at room temperature at a high concentration, and the silicon oxide particles easily aggregate at a high concentration. As a result, the particle diameter is several μm to several This is because a 10 μm solid was produced in the paint. This solid causes nozzle clogging. Further, when a solid having a particle size of several μm to several tens of μm is contained in the paint, irregularities of several μm are formed on the film surface, the glossiness of the appearance is lost, and the design is deteriorated. Similarly, in other coating methods such as flow coating and spin coating, surface irregularities caused by solids of several μm to several tens of μm deteriorate design properties.

  Therefore, the minimum proportion of solvent is 90% by weight. Considering the long-term stability of the paint, it is preferably 95% by weight or more. However, since it becomes difficult to ensure the film thickness at the time of film formation if diluted too much, the ratio of the solvent is preferably 99% by weight or less.

(5) Colloid composed of inorganic oxide particles containing silver The coating material of the present invention contains a colloid in a state where silver is adhered to the inorganic oxide particles in order to impart antibacterial properties. For example, silver is attached to the inorganic oxide particles by the following method. First, an anion exchange resin is added to a colloid composed of inorganic oxide particles such as silicon oxide, aluminum oxide, titanium oxide and zirconium oxide having a particle diameter of several nanometers to several tens of nanometers, and an aqueous silver nitrate solution is added little by little in this state. . By this operation, nitrate ions are trapped in the anion exchange resin, silver is adhered to the inorganic oxide particles, and a colloid composed of inorganic oxide particles to which silver is adhered is produced. Silver adheres to the inorganic oxide with a silver oxide structure. The used anion exchange resin can be removed by filtration or the like.

  In consideration of adhesion with silver, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, iron oxide, antimony oxide, and cerium oxide are suitable as the inorganic oxide particles.

  The smaller the particle size, the larger the surface area per unit weight. Therefore, the smaller the particle size, the larger the amount of silver deposited per unit weight, and the antibacterial properties are improved. On the other hand, when the particle diameter of the inorganic oxide particles is increased, the influence of the specific gravity difference with the solvent is increased, so that the inorganic oxide particles are easily precipitated. In order to make precipitation less likely, that is, to improve the stability of the colloid, it is preferable that the particle diameter is small.

  In order to exhibit antibacterial properties, the amount of colloid in the state where silver is adhered to the inorganic oxide particles in the coating is about 1 to 1000 ppm in terms of silver. If the amount is less than 0.5 ppm, for example, 0.5 ppm is not sufficient for imparting antibacterial properties to the blower fan of the air conditioner. In the experiment by the inventor, mold was generated in the blower fan at a considerable rate after about one year in normal operation. However, no mold was observed at 1 ppm even after 1 year. However, when the temperature was kept at 30 ° C. and the humidity 90% for one year, mold was generated even at 10 ppm in terms of silver. On the other hand, if it exceeds 1000 ppm, the price of the colloid in a state where silver is adhered to the inorganic oxide particles will be approximately half or more of the price accounting for the material cost of the paint, which is not realistic. Therefore, the addition ratio of the colloid in a state where silver is adhered to the inorganic oxide particles is 1 to 1000 ppm, more preferably 10 to 1000 ppm in terms of silver.

  Other antibacterial agents were also examined. Organic antibacterial agents include pyridinium salt materials such as cetylpyridinium chloride, pyridine-N-oxide, dipyridyl-N-oxide, compounds having a benzimidazole structure, compounds having a thiazole structure, compounds having an isothiazole structure, etc. Is mentioned. However, these organic compounds gradually dissolve in water attached to the surface, particularly under high humidity conditions. When the water oozes out from the membrane to the membrane surface and dries, the antibacterial agent precipitates. Since the precipitates are scattered by the rotation of the blower fan, the antibacterial action of the film is lost by long-term use.

  Since this tendency is slight in inorganic compounds including silver, the antibacterial action lasts for a long time. On the other hand, copper-based, zinc-based, nickel-based, cobalt-based and other compounds that are not silver but are inorganic compounds have a weak antibacterial effect compared to silver, and need to be added in large quantities to the paint. If a large amount of such an inorganic compound is added, the ratio of the silicon compound having a hydrolyzable residue added as a binder of the film in the paint is decreased, and the physical strength of the film is decreased. . Therefore, a silver antibacterial agent is used in the paint of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the paint of the present invention is applied to a blower fan provided in an indoor unit of an air conditioner.

  First, the whole structure of the air conditioner 1 of a present Example is demonstrated using FIG. 1, FIG. FIG. 1 is a configuration diagram of an air conditioner 1 of this embodiment, and FIG. 2 is a side sectional view of the indoor unit 2 of FIG.

  In FIG. 1, an air conditioner 1 is configured by connecting an indoor unit 2 and an outdoor unit 3 with a connection pipe 5, and air-conditions the room. Basic internal structures such as a blower fan 14, filters 15, 15 ′, a heat exchanger 16, a dew tray 17, an up / down wind direction plate 18, and a left / right wind direction plate 19 are attached to the housing 9 of the indoor unit 2. The heat exchanger 16 is disposed on the suction side of the blower fan 14 and is formed in a substantially inverted V shape.

  A basic internal structure such as the blower fan 14 attached in the housing 9 is included in the indoor unit 2 by attaching the decorative frame 8. A front panel 7 is attached to the front surface of the decorative frame 8. Below the front panel 7, a display unit 11 that displays an operation status and a light receiving unit 10 that receives an infrared operation signal from a separate remote controller 12 are arranged.

  In FIG. 2, by operating the blower fan 14 (the entire shape is shown in FIG. 3), air flows as indicated by white arrows, and dust in the passing air is collected by the filters 15 and 15 '. . The filters 15 and 15 ′ are for removing dust contained in the sucked room air, and are arranged so as to cover the suction side of the heat exchanger 16. The blower fan 14 is disposed in the center of the indoor unit 2 so as to suck room air from the air suction port 6 and blow it out from the air blower port 13.

  The air conditioner 1 circulates room air to the heat exchanger 16 to produce conditioned air that has been heated, cooled, or dehumidified, and blows this into the room to make the room environment comfortable. At this time, since the filters 15 and 15 ′ for removing dust in the circulating air are arranged on the suction side of the heat exchanger 16, most of the dust in the circulating air is collected by the filters 15 and 15 ′. On the other hand, part of the dust enters the inside of the air conditioner 1 through the mesh of the filters 15, 15 ′. The dust that has entered the inside of the air conditioner 1 collides with the inner wall facing the air passage in the air conditioner 1, is bounced back, and returns to the airflow again. The dust that has returned into the airflow is blown out into the room from the outlet of the air conditioner 1.

  However, a part of the dust that has entered the air conditioner 1 is not bounced back due to the influence of electrostatic force, gravity, chemical affinity, etc. Adhere to structures. Since electrostatic force acts greatly in a low humidity environment, dust tends to adhere particularly in low humidity winter.

  Some of the dust adhering to the inner wall and the like is separated from the wall in a relatively short time due to the airflow and other influences, and is carried out of the air conditioner 1 by riding on the airflow. Adhere to the time wall. When a long time elapses after the attachment, physicochemical changes occur depending on the type of dust, and fungi such as fungi grow and grow and adhere firmly to the wall with their secretions and hyphae. If it becomes like this, the ventilation fan will be clogged with the dust which adhered, and it will have a bad influence on ventilation performance. Also, dust in the air is more likely to adhere to the wall due to the viscosity of the secretions. If it does so, a bad odor will arise from fungi, spores, such as mold, will disperse, etc., and the indoor environment will be deteriorated.

  Therefore, it is necessary to prevent dust that has entered the air conditioner 1 from adhering to the inner wall or the like, or to exhibit antibacterial action even if it is temporarily attached. Note that the term “antibacterial” is not defined purely theoretically or academically, so it roughly applies to the following cases. In other words, for sterilization inhabiting the living environment, the effect is not temporary but lasts for several weeks to several years, sometimes several decades, and the sterilization level is below antibacterial and sterilization. Maintaining microbiological hygiene is called antibacterial (from a white paper issued by the Ministry of Economy, Trade and Industry).

  When the hydrophilic film having antibacterial properties of the present embodiment is formed on the blower fan 14, water molecules are retained on the surface, so that the surface resistance is lowered and dust is less likely to adhere. However, since dust cannot be completely prevented from adhering, the hydrophilic film having antibacterial properties of this example contains a silver-based antibacterial agent so that fungi such as mold in the attached dust do not grow. As a result, it is possible to suppress environmental deterioration due to the generation of malodors from fungi or the scattering of spores such as mold.

  The color of the blower fan is determined in consideration of the appearance color, structure, etc. of the air conditioner. However, since the formed film contains silicon oxide particles, it may appear whitish when part of the film aggregates. When the color of the blower fan is black or a relatively dark color, the whitishness that accompanies agglomeration may be a concern, so the color of the blower fan is preferably gray or white, where these are not noticeable.

  FIG. 4 shows a cross-sectional photograph taken by a transmission electron microscope (TEM) of a sample in which a hydrophilic film 30 having antibacterial properties is formed on the surface of the resin layer 29. The dark portion is the portion where the silicon oxide content is high. The average film thickness of the hydrophilic film 30 having antibacterial properties is approximately 100 nm, and silicon oxide particles are dispersed therein. The white layer on the antibacterial hydrophilic film 30 is a carbon layer formed as a protective layer when the TEM sample is manufactured, and is not a constituent part of the antibacterial hydrophilic film 30 of this embodiment. .

  Next, preparation of a coating material for forming an antibacterial hydrophilic film will be described. As silicon oxide particles, Aerosil 130 manufactured by Nippon Aerosil Co., Ltd. (average particle size is 16 nm) (15 g) is added to n-butanol solution (85 g), and then dispersed with a homogenizer. The viscosity increases at the beginning of addition, but the viscosity gradually decreases by dispersing with a homogenizer. Disperse with a homogenizer until the viscosity is approximately constant. As a silicon compound having a hydrolyzable residue, an n-butanol solution (290 g) containing 2% by weight of silica sol, n-butanol (300 g), and then tetrahydrofuran (300 g) are added.

  A method for preparing a colloid containing silver having antibacterial properties will be described. First, a 3 wt% aqueous silver nitrate solution (5 g) is slowly added to the stirring 20 wt% silicon oxide colloidal dispersion (5 g) over about 10 minutes. In addition, an anion exchange resin in an amount necessary for trapping nitrate ions in the aqueous silver nitrate solution to be added is previously added to the silicon oxide colloid dispersion. After adding the aqueous silver nitrate solution, the anion exchange resin is removed by filtration. By adding this liquid to a liquid in which silicon oxide particles, silica sol, n-butanol, and tetrahydrofuran are first mixed, a coating material for forming a hydrophilic film having antibacterial properties is prepared. In this paint, about 100 ppm of silver oxide colloid adhered with silver is added in terms of silver.

  Next, the formation of the antibacterial hydrophilic film according to the present embodiment will be described. The paint of this embodiment is filled in a paint tank of a spray gun and sprayed toward the acrylic substrate. Since the solid content in the paint is about 2% by weight and the specific gravity is about 1.7, the coating amount per unit area is estimated with reference to this.

  After application, the film is dried at 70 ° C. for 20 minutes to form an antibacterial hydrophilic film on the acrylic substrate. Here, samples having different film thicknesses with average film thicknesses of about 50, about 100, about 300, and about 350 nm, respectively, were prepared, and the adhesion to the acrylic substrate was examined by a cross-cut method of JIS K5400. No peeled portion was observed in the films having an average film thickness of about 50, about 100, or about 300 nm. However, several film peelings were observed in the film having an average film thickness of about 350 nm.

  A similar test was performed using a polycarbonate substrate and an acrylonitrile-styrene polymer substrate containing glass fiber instead of the acrylic substrate. As a result, no film peeling was observed until the film thickness was about 300 nm, but several film peelings were observed in the film having an average film thickness of about 350 nm. Therefore, the thickness of the antibacterial hydrophilic film is preferably 50 to 300 nm.

  When the part where the film of the sample having an average film thickness of 350 nm was peeled was observed, a part of the film remained on the substrate. That is, not all the 350 nm films were peeled off, but some tens to 300 nm of them adhered to the tape, and the rest remained on the substrate. This indicates that the film was peeled off by cracking inside the film, not at the interface with the substrate. The reason why such peeling occurred is considered to be that the film thickness became too thick. Therefore, the film thickness is desirably 300 nm or less.

  Next, hydrophilic paint: Colcoat Co., Ltd., Colcoat N103X13.6 wt%, Binder: Nissan Chemical Industries, Ltd., IPA-ST-UP 39.4 wt%, Solvent: Butanol 46.9 wt% To prepare. To this hydrophilic component, a solvent: tetrahydrofuran 30% by weight, an antibacterial agent: JGC Catalysts & Chemicals Co., Ltd., UA-X 1.0% by weight is prepared to prepare a hydrophilic paint. UA-X used here is a dispersion of inorganic oxide particles containing silver.

  The hydrophilic paint is spray-coated on the blower fan 14, and a hydrophilic coating film 32 is formed on the blower fan blade 31 as shown in a blade cross-sectional view of the blower fan 14 shown in FIG. In film formation, as described above, thinning is important for ensuring the adhesion of the blower fan 14 to the base resin. For thin film formation, spray coating is preferred to dipping in consideration of mass productivity such as coating composition concentration man-hours and film formation time. In order to make the volatility close to solvents such as xylene and to slightly swell the surface of the blade, tetrahydrofuran is mixed into the paint to promote evaporation of the solvent, thereby reducing the film thickness and improving the adhesion. be able to.

The dust adhesion suppressing effect, coating film adhesion, and durability of the blower fan 14 formed with this hydrophilic paint will be described with reference to FIG. The dust adhesion suppression test was conducted by installing the indoor unit 2 in a 1 m ³ sealed box, and dropping the indoor unit 2 for 10 minutes while dripping moisture while heating the salad oil in the box. While operating in a weak wind, 20 g of pseudo dust mixed with 11 kinds of JIS powder of Kanto loam layer and yarn cotton linter is sprayed to forcibly adhere the dust to the blower fan 14. The difference in weight of the blower fan 14 before and after the test was defined as the dust adhesion amount, and the dust adhesion amount with and without hydrophilic coating was measured and compared (n = 5). As a result of the test, when the dust adhesion amount of the blower fan 14 without hydrophilic coating was set to 100, it was confirmed that the blower fan 14 with hydrophilic coating was 17, and about 80% dust adhesion could be suppressed. Then, the durability test which left the ventilation fan which performed this test for -20 degreeC, 60 degreeC, each 2 hours, 20 cycles repeated exposure, and was immersed in 20 degreeC +/- 5 degreeC water for 240 hours was done. Thereafter, a dust adhesion test was performed again. As a result of the test, when the dust adhesion amount of the blower fan 14 without hydrophilic coating was 100, the blower fan 14 with hydrophilic paint was 16. It was confirmed that even after durability tests such as repeated cooling and heating, the hydrophilic film was retained by improving the adhesion of the paint to the solvent with tetrahydrofuran, and the dust adhesion preventing function due to hydrophilicity was not lowered.

  Next, the antibacterial property of this hydrophilic paint will be described with reference to FIG. The antibacterial test was conducted according to the antibacterial test of JISZ2801 plastic. As a test sample, a JIS-standard-designated polyethylene film having no antibacterial action as a control group, an antibacterial agent: 1% by weight, 3% by weight, 5% by weight of UA-X manufactured by JGC Catalysts & Chemicals Co., Ltd. added to the above-mentioned hydrophilic components Four types of paints were applied to the blower fan resin pieces. Each test sample was inoculated with Escherichia coli and Staphylococcus aureus, and then the antimicrobial activity was evaluated by measuring the number of bacteria (CFU: Colony forming unit) after 24 hours. The test was conducted at the Japan Spinning Inspection Association. As a result of the test, the test specimens to which 1%, 3%, and 5% by weight of the antibacterial agent were added had 5 digits (99.999%) to 6 digits (99.9999%) of bacteria compared to the control specimen The number reduction effect was confirmed. Accordingly, the antibacterial agent has a sufficient antibacterial effect even at 1% by weight, and the antibacterial agent is desirably 1% by weight for cost reduction.

  As described above, the coating material of this example is a coating material for forming a hydrophilic film having antibacterial properties on the surface of a resin, and includes a silicon compound having hydrolyzable residues, silicon oxide particles, alcohol, cyclic An organic solvent having an ether structure and a colloid composed of inorganic oxide particles containing silver are contained. By applying such paint to the blower fan 14, dust adhesion can be prevented and antibacterial properties can be imparted, so that the blower fan 14 can be kept clean.

  That is, by coating the surface of the resin base material of the blower fan 14 with the paint of the present embodiment, the surface resistance value of the blower fan is reduced and dust adhesion can be prevented. Moreover, the growth of mold and bacteria can be suppressed, and the blower fan can be kept clean. Furthermore, since the clogging of the blower fan due to dust is suppressed, it is possible to suppress a decrease in air conditioning performance and an increase in noise.

The film formed from the paint of this example has high hydrophilicity, and the contact angle between the resin surface and water is 10 ° or less. In addition, since water molecules are retained on the surface, the surface resistance is low when the relative humidity is 70%, the surface resistance is 10 ⁸ Ω or less, and when the relative humidity is 50%, the surface resistance is 10 ⁹ Ω or less, Even when the relative humidity is 30%, the surface resistance is 10 ¹⁰ Ω or less.

  Furthermore, although the surface is hygroscopic and the surface is wet, bacterial growth such as mold can be suppressed. This is because inorganic oxide particles having silver are mixed in the film.

  In the paint of Example 1, 1,4-dioxane (300 g) was added instead of tetrahydrofuran (300 g) to prepare a paint, and the adhesion of the film was examined by a cross-cut method. As a result, even when 1,4-dioxane (300 g) was added instead of tetrahydrofuran (300 g), the result was the same as that of the paint to which tetrahydrofuran was added.

  In the coating material of Example 1, the amount of tetrahydrofuran added is 30% by weight. Therefore, five types of paints were prepared in which the amount of tetrahydrofuran added was 0 wt%, 15 wt%, 20 wt%, 40 wt%, and 45 wt%. These paints were applied to an acrylic substrate in the same manner as in Example 1 and dried to form a film.

  As a result, when the amount of tetrahydrofuran added was 20,40% by weight, the adhesion of the film was examined by a cross-cut method, and no film peeling was observed between the film thicknesses of 50 to 300 nm. When the amount of tetrahydrofuran added was 45% by weight, the acrylic substrate was slightly dissolved and turned white.

  When the amount of tetrahydrofuran added was 15% by weight, the adhesion of the film was examined by a cross-cut method, and no film peeling was observed between the film thicknesses of 50 to 100 nm. However, several peelings were observed in the 300 and 350 nm films.

  When the amount of tetrahydrofuran added was 0%, that is, when it was not added, the adhesion of the film was examined by a cross-cut method.

  When the amount of tetrahydrofuran added is 100%, the acrylic substrate is dissolved. In the case of a paint, tetrahydrofuran is diluted with other members, but when the added amount exceeds 40% by weight, the acrylic substrate is slightly dissolved. Therefore, the upper limit of addition of tetrahydrofuran is preferably 40% by weight.

  On the other hand, when the amount of tetrahydrofuran added was 0% or 15% by weight, the adhesion of the film was lowered. By adding tetrahydrofuran, the substrate is slightly dissolved or swollen, which is considered to cause an anchor effect between the film and the substrate and improve the adhesion. If the amount of tetrahydrofuran added is 0% or 15% by weight, this anchor effect is not sufficient, and it is considered that the adhesion is lowered. Therefore, the lower limit of the addition amount of tetrahydrofuran is preferably 20% by weight.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Indoor unit 3 Outdoor unit 5 Connection piping 6 Air suction inlet 7 Front panel 8 Cosmetic frame 9 Case 10 Light-receiving part 11 Display part 12 Remote control 13 Air blower outlet 14 Fans 15 and 15 'Filter 16 Heat exchanger 17 Dew tray 18 Vertical wind direction plate 19 Left and right wind direction plate 20 Blower motor 29 Resin layer 30 Antibacterial hydrophilic film 31 Blower fan blade 32 Hydrophilic coating film

Claims (7)

A heat exchanger and a blower fan for flowing air through the heat exchanger;
Forming a hydrophilic film having antibacterial properties by the paint on the surface of the resin of the blower fan ,
The paint possess silicon compound having a hydrolysable residue, silicon oxide particles, an organic solvent medium of alcohol and cyclic ether structure,
The organic solvent having the cyclic ether structure is tetrahydrofuran, and the amount of the tetrahydrofuran added is 20 to 40% by weight . 2. The air conditioner according to claim 1, wherein the paint has a colloid made of inorganic oxide particles containing silver. The air conditioner according to claim 1 or 2, wherein the silicon oxide particles have an average particle diameter of 10 to 100 nm as measured by a dynamic light scattering method. 4. The air conditioner according to claim 1, wherein the alcohol is a mixture of alcohols having 1 to 4 carbon atoms and 50% or more is n-butanol. The air conditioner according to any one of claims 1 to 4 , wherein a total paint content ratio of the alcohol and the organic solvent having the cyclic ether structure is 95 to 99% by weight. 6. The air conditioner according to claim 1 , wherein the hydrophilic film has an average thickness of 50 to 300 nm. The air conditioner according to claim 6 , wherein the arithmetic average roughness of the hydrophilic film is 2 to 30 nm.