COATING COMPOSITION AND USES THEREOF
A coating composition comprising a photocatalyst composite and a silicone resin is provided, in which the content of the photocatalyst composite ranges from about 1% to about 70% by weight (wt %), based on the total weight of the coating composition, and the photocatalyst composite contains a heat insulation material and a photocatalyst material. An energy-saving material is further provided, which includes a substrate and a film formed from the coating composition of the present invention on at least one of the surfaces of the substrate. The energy-saving material is capable of effectively shielding off infrared (IR) light, substantially decreasing indoor temperature, and reducing power consumption. In addition, in the presence of the photocatalyst which can absorb ultraviolet light, the material also exhibits good superhydrophilic and self-cleaning properties and provides antimicrobial and deodorization effects.
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1. Field of the Invention
The present invention relates to a coating composition, which can be coated on a substrate, so as to enable the surface of the substrate to have self-cleaning and heat insulation effects. The present invention further relates to an energy-saving material containing a film formed from the coating composition of the present invention.
2. Description of the Prior Art
There are many materials for shielding the heat effect of infrared light available in the market, for example, glass curtain of a building, automobile glass, and heat insulation paper. In short, the materials are provided for the purpose of allowing the sunlight to pass through to provide light, while the heat source (that is, heat effect of infrared light) is expected to be insulated. However, with an existing glass having the infrared light shielding property as an example, the production cost is too high and the effect is less satisfactory. For example, it is known that an ultra thin infrared light absorption silver film may be embedded in the glass to shield the infrared light; however, the preparation cost is high, and silver is easily oxidized, and thus loses the infrared light shielding effect.
In addition, a material (for example, titanium dioxide of high refractive index and silica of low refractive index) capable of shielding the infrared light may be applied on glass or a lens by vacuum evaporation, to form a film capable of shielding the infrared light. However, the film thus formed has the following disadvantages of high cost, complex manufacturing process, and unsatisfactory effect, thus not meeting the requirement of economic benefits.
In addition to the above two methods, an alternative low-cost solution is proposed, in which a pigment or a dye is admixed in the glass to absorb the infrared light in sunlight. However, upon irradiation with intense sunlight or scattered light, a fume like haze occurs to this kind of glass containing pigment or dye, and thus the infrared light absorbing performance is influenced, and the pigment or dye will be decomposed after long time of use and lose the corresponding effects.
Furthermore, it is known that the photocatalyst has a function of absorbing light (especially, UV light) to excite the electrons, and thus has a photocatalytic performance. After excitation with light, the photocatalyst material activates water molecules or oxygen molecules in the air, to form hydroxyl radicals or negative oxygen ions for oxidation reduction reaction, so as to decompose pollutants in the environment. Thereby, the photocatalyst material may be used to remove the pollutants in the air or waste water, and inhibit bacteria attached to a surface, so as to achieve an antimicrobial effect. Furthermore, upon irradiation with light, free radicals or negative oxygen ions are formed and released from the surface of the photocatalyst material due to the presence of hydrogen molecules, and an empty position is formed at the position originally occupied by oxygen. In this case, if any, the water molecules in the environment will occupy the empty position and lose a proton, to form a hydroxyl group, such that the photocatalyst material exhibits a superhydrophilic property, thereby achieving the self-cleaning and anti-fog effect.
Generally, as for a heat insulation film or window glass coating having the infrared light shielding and UV light absorbing functions, multi-layer processing is required to be performed on a substrate, to form a composite film, the preparation process is complex, and the preparation cost is high. Therefore, continuous efforts are currently directed to provide a material having infrared light shielding and UV light absorbing functions.
SUMMARY OF THE INVENTIONIn order to achieve the above objectives, the present invention provides a coating composition comprising a photocatalyst composite and a silicone resin, in which the content of the photocatalyst composite is about 1 to 70% by weight (wt %), based on the total weight of the composition, and the photocatalyst composite comprises:
(1) a heat insulation material, selected from the group consisting of antimony tin oxide (ATO), indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium zinc oxide (GZO), and a combination thereof; and
(2) a photocatalyst material, selected from the group consisting of titanium dioxide, zinc oxide, strontium titanate, and tin oxide, and a combination thereof, wherein the content of the photocatalyst material is about 10 to 90 wt %, based on the total weight of the photocatalyst composite.
The present invention further provides an energy-saving material, which includes a substrate and a film applied on at least one of the surfaces of the substrate, in which the film is formed from the coating composition of the present invention, and has self-cleaning and heat insulation effects.
The coating composition of the present invention can effectively insulate or reflect the heat-causing infrared light, such that the transmittance of the infrared light is greatly reduced. The photocatalyst material exhibits an UV light absorbing capability, a self-cleaning function, and anti-fog, antimicrobial, and deodorization effects. Furthermore, the coating composition of the present invention may be applied on a substrate through a common coating method, and thus the preparation process is relatively simple and cheap.
The term “about” used herein means a variation of ±10% of an indicated value.
The coating composition of the present invention comprises a photocatalyst composite and a silicone resin, in which the content of the photocatalyst composite is about 1% to about 70 wt %, and preferably about 40% to about 60 wt %, based on the total weight of the composition. If the content of the photocatalyst composite is lower than 1 wt %, the infrared light shielding and UV light absorbing effects of the composition is insufficient; and if the content is higher than about 70 wt %, the dispersivity of the photocatalyst composite in the resin is sharply decreased, and the coated composition is likely to fall off.
The photocatalyst composite comprises a heat insulation material and a photocatalyst material, in which the content of the photocatalyst material is about 10% to about 90 wt %, and preferably about 40% to about 85 wt %, based on the total weight of the photocatalyst composite.
The photocatalyst composite normally has a particle size of from about 2 to about 100 nanometers (nm), preferably from about 5 to about 45 nm, and more preferably 10 to 35 nm. If the particle size is smaller than 2 nm, the photocatalyst composite is not easy to produce and is not practical, and if the particle size is greater than 100 nm, the overall surface area becomes small, and thus the transmittance of the visible light decreases, and the heat insulation effect is poor. As the particle size of the photocatalyst composite of the present invention is smaller than the wavelength of visible light (from about 380 nm to about 780 nm), when the photocatalyst composite is irradiated with light, the transmitted light will not be seriously scattered, thereby avoiding the adverse influence on the quality of the transmitted light.
The heat insulation material in the photocatalyst composite of the present invention is required to have an infrared reflectivity of about 70% or higher, and can be selected from the group consisting of antimony tin oxide (ATO), indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium zinc oxide (GZO), and a combination thereof.
According to a preferred embodiment of the present invention, when using ITO or ATO as the heat insulation material of the photocatalyst composite, substantially a same heat insulation effect can be achieved at a less material dose, as compared with other materials, thus the photocatalyst composite is more cost effective. Moreover, it is found that when the coating composition includes ITO, it not only can effectively reflect infrared light but exhibits a better visible light transmittance and can be advantageously used as a transparent heat insulation material.
According to a preferred embodiment of the present invention, preferred transparency can be achieved when ITO is used as the heat insulation material of the photocatalyst composite. In addition, it is found that when using ITO in the coating composition of the present invention, the infrared light can be effectively reflected, and substantially a same heat insulation effect can be achieved at a less material dose, compared with other materials, thus being more cost effective.
In addition to the heat insulation material capable of shielding off or reflecting IR light, the photocatalyst composite in the coating composition of the present invention further comprises a photocatalyst material. The photocatalyst material has a function of absorbing UV light to excite electrons, and thus has photocatalytic property. Upon excitation with light, the photocatalyst material activates water molecules or oxygen molecules in the air to form hydroxyl free radicals or negative oxygen ions for oxidation reduction reaction, so as to decompose pollutants in the environment. Therefore, the photocatalyst material may be used to remove the pollutants in the air or waste water, and inhibit bacteria attached to a surface so as to achieve an antimicrobial effect. Furthermore, the photocatalyst material also exhibits a superhydrophilic property, and the moisture may form into an aqueous film between the fouling and the photocatalyst material, such that the adhesion of the fouling is reduced, and the fouling on the aqueous film can be easily removed after being washed with water or rainwater. Thus, the photocatalyst material has a UV light absorbing capability and a self-cleaning function, and provides anti-fog, antimicrobial, and deodorization effects.
The photocatalyst material suitable for the photocatalyst composite of the present invention can be any of those well known to persons skilled in the art, and may be, for example, titanium dioxide, zinc oxide, strontium titanate (SrTiO3), tin oxide, or a mixture thereof, and is preferably titanium dioxide which is relatively harmless to the environment or human body. In terms of catalyst performance, titanium dioxide in an anatase crystal structure is preferred. Furthermore, the particle size of the photocatalyst material is required to be smaller than about 100 nm, so as to exhibit a photocatalytic effect. For example, the particle size of titanium dioxide is suitably about 1 to about 100 nm, and preferably about 5 to about 30 nm; if the particle size is less than 1 nm, titanium dioxide is difficult to be produced and not easy to be dispersed, and if the particle size is greater than 100 nm, the photocatalytic effect will be greatly decreased.
The coating composition of the present invention comprises a binder which can be, for example, but is not limited to an acrylic resin, fluorocarbon resin or silicone resin. To prevent the photocatalyst from being oxidized and being decomposed, the binder is preferably a silicone resin. The silicone resin contained in the coating composition of the present invention is present in an amount of about 30 wt % to about 99 wt %, and preferably about 40 wt % to about 60 wt %, based on the total weight of the coating composition.
The silicone resin useful for the present invention is not particularly limited and can be that well known to persons skilled in the art, that is, an organic polysiloxane resin with a main chain consisting of repeating Si—O bonds where hydrogen atoms or organic radicals are directly bonded to the silicon atoms, and of the formula [RnSiO4-n/2]m, wherein R represents hydrogen or an organic radical, and independently is hydrogen, C1-6 alkyl, C2-5 epoxy, or C6-14 aryl, and preferably is hydrogen, methyl, ethyl,
or phenyl; n is the number of the hydrogen atom(s) or organic radical(s) bonded to the silicon atom and is in the range from 0 to 3; and m represents the degree of polymerization, and is an integer of 2 or more. The steps for constructing the chemical structure of polysiloxane include determining the length of the polymeric chain, branching, and locating the places for attaching hydrogen(s) or organic group(s). In view of the chemical structure, letters M (denoting monofunctional group), D (difunctional group), T (trifunctional group), and Q (tetrafunctional group) can be used to represent the structural group(s) introduced into the polymeric molecule.
Examples of Commercially available silicone resins include, but are not limited to KBM-1003, KBE-402, KBE-403, KBM-502, KBM-04, KBE-13, and KBE-103 manufactured by Shin Etsu Company; and Z-6018 and 3037 manufactured by Dow Corning Company.
The silicone resins can be used in single species and in combination of two or more species. The silicone resin useful for the present invention can be an oligomer of the formula R1O—[SiR2O]w—SiR2(OR1) in which w is an integer of 1 to 1000, R is as defined hereinbefore and R1 is independently H, C1-3 alkyl or C2-5 epoxy and preferably is methyl, ethyl, or
Such oligomer imparts the inventive coating composition with better film-forming property, dispersivity, and ductility, and a high surface hardness after being cured.
The suitable preparation method for the silicone resin used in the present invention is not particularly limited. According to the preferred embodiment of the present invention, the silicone resin is formed through a sol-gel process. The sol-gel process includes suspending a raw material of solid particles of about several hundred nanometers in size (generally, an inorganic metal salt), in a liquid. In a typical sol-gel process, the reactant will undergo a series of hydrolysis and polymerization reactions, to generate a colloidal suspension, in which the resulting substance in the colloidal suspension condenses into a new phase of a solid polymer containing solution, that is, gel. The properties of the prepared sol-gel depends on the species of the raw material, the species and concentration of the catalyst, the pH value, the temperature, the amount of the solvent, and the species and concentrations of the alcohol and the salt.
The coating composition of the present invention may optionally comprise nano-size inorganic particulates, such that the surface of the photocatalyst composite is covered with a layer of the inorganic particulates, so as to avoid direct contact of the photocatalyst with the substrate when the coating composition is coated onto the surface of the substrate, and to avoid the deterioration of the substrate that can be easily caused due to the oxidation property of the photocatalyst. If present, the amount of the inorganic particulates is about 0.1 wt % to about 40 wt %, based on the total weight of the composite material. The inorganic particulates useful for the present invention are not particularly limited, and generally may be selected from silica (SiO2), alumina (Al2O3), cadmium sulfide (CdS), zirconia (ZrO2), calcium phosphate (Ca3(PO4)2), calcium oxide (CaO), and a combination thereof, with SiO2 being preferred. According to a preferred embodiment of the present invention, the photocatalyst composite is coated with a layer of porous inorganic particulates. Specifically, the photocatalyst composite in the composite material of the present invention is coated with a layer of porous inorganic particulates, and thus will not directly contact and destroy the substrate, and external impurities (for example, odor molecules and bacteria) can penetrate the porous inorganic particles through diffusion, arrive at and be absorbed on the photocatalyst material, and are photocatalytically decomposed, thereby achieving the cleaning, antimicrobial and deodorization purposes.
An organic solvent may be further added to the coating composition of the present invention, depending on the requirements in application. When the organic solvent is used in the coating composition of the present invention, the amount is about 1 wt % to about 95 wt %, and preferably about 65 wt % to about 90 wt %, based on the total weight of the coating composition. The organic solvent may be any of those well known to persons skilled in the art, and may be, for example, but is not limited to, an alkane, an aromatic hydrocarbon, an ester, a ketone, an alcohol, or an ether alcohol. The alkane solvent useful in the present invention may be selected from the group consisting of n-hexane, n-heptane, iso-heptane, and a mixture thereof. The aromatic hydrocarbon solvent useful in the present invention may be selected from the group consisting of benzene, toluene, and xylene, and a mixture thereof. The ketone solvent useful in the present invention may be selected from the group consisting of methyl ethyl ketone (MEK), acetone, methyl iso-butyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone, and a mixture thereof. The ester solvent useful in the present invention may be selected from the group consisting of iso-butyl acetate (IBAC), ethyl acetate (EAC), butyl acetate (BAC), ethyl formate, methyl acetate, ethoxyethyl acetate, ethoxypropyl acetate, ethyl iso-butyrate, propylene glycol monomethyl ether acetate, and pentyl acetate, and a mixture thereof. The alcohol solvent useful in the present invention may be selected from the group consisting of ethanol, iso-propanol, n-butanol, and iso-pentanol, and a mixture thereof. The ether alcohol solvent useful in the present invention may be selected from the group consisting of ethylene glycol monobutyl ether (BCS), ethylene glycol monoethyl ether acetate (CAC), ethylene glycol monoethyl ether (ECS), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate (PMA), and propylene glycol monomethyl propionate (PMP), and a mixture thereof.
The present invention further provides an energy-saving material, which comprises a substrate and a film formed from the coating composition as described above on at least one surface of the substrate. The coating composition of the present invention can be applied onto the at least one surface of the substrate by a common application method, which is for example, coating, spraying, or dipping, and then dried to form a smooth film. The existing energy-saving materials generally have the disadvantages of low coating hardness and being likely to be scratched, such that the coating is very likely to be scratched after a long period of time, and the scratched coating in turn seriously influences the aesthetic appearance of an article, such as window. According to a preferred embodiment of the present invention, the film of the energy-saving material has a pencil hardness of H or higher and preferably 3H or higher, as measured according to JIS K5400 standard method, and can effectively overcome the above-mentioned disadvantages.
The above-mentioned substrate includes, but is not limited to, glass, plastic, heat insulation plate for buildings, metal, ceramic tile, wood, leather, stone, concrete, mural, fiber, cotton fabric, appliances, lighting devices, and computer casings, with glass and heat insulation plate for buildings being preferred.
According to a specific embodiment of the present invention, the energy-saving material includes a glass and a film formed by applying the foregoing coating composition by coating, spraying, or dipping on at least one surface of the glass. The film has a thickness of about 0.5 to about 50 micrometers. The energy-saving material according to the present invention has a transmittance of the visible light under wavelength of 550 nm of about 70% or more, preferably of about 90% or more. The energy-saving material of the present invention has a good visual effect and an infrared light (thermal radiation) reflectance of about 70% or higher, and exhibits a good heat insulation effect, so it can substantially decrease the indoor temperature and reduce power consumption, has a better energy-saving effect and a higher transmittance of visible light, compared with a glass attached with a traditional heat insulation film available in the market, and thus having the advantages of greatly reduced cost, simple application, and wide application in glass curtain for buildings or automobile glass. Furthermore, almost all the heat insulation materials (such as lanthanum hexaboride) contained in the coating compositions for energy-saving materials available in the market absorb, rather than reflect, the infrared light in sunlight, and the absorbed infrared light is converted into heat energy, and stored in glass, such that the surface temperature of the glass rises, and thus the risk of glass cracking exists.
Moreover, the photocatalyst composite in the coating composition of the present invention has superhydrophilic property, such that the moisture in the air is attracted to form a super thin aqueous film between the fouling and the photocatalyst composite and to reduce the adhesion of the fouling. In addition, the photocatalyst can also oxidize organic fouling particles and break down the structure thereof, such that the particles will not be attached on the surface of the glass. Upon rainfall, due to the effect of superhydrophilic property, the rain water evenly penetrates to an interface between the fouling and the photocatalyst, and the fouling on the aqueous film can be easily washed off when the rain water is accumulated to a sufficient extent, such that the frequency of maintaining the surface of a common glass clean with the aid of human power is lowered, and the self-cleaning effect is achieved.
In the past, for obtaining energy-saving materials, treatments for shielding infrared light and absorbing UV light needed to be performed on the substrate, so effects both on shielding infrared light and absorbing UV light can be achieved only after a multi-layer processing was conducted on the substrate. However, by using the coating composition of the present invention, an energy-saving material having the effects on shielding infrared light and absorbing UV light can be obtained only through one time application treatment on the surface of the substrate. As the film applied on the substrate contains photocatalyst material, it can absorb UV light, thus providing self-cleaning, anti-fog, antimicrobial, and deodorization efficacies; and due to the presence of the heat insulation material, the film can also effectively reflect infrared light so as to reduce the transmittance of the infrared light while allowing the visible light to pass through. In addition, since the size of the particles contained in the film is less than the wavelengths of the visible light, the particles will not scatter the transmitted light and will not influence the quality of the transmitted light, and the transparency of the substrate can be maintained.
The present invention further provides a method for preparing a coating composition, which includes obtaining an intermediate product of titanium sulfate through hydrolysis of titanium tetrachloride, then adding a heat insulation material, to obtain a photocatalyst composite powder at a low temperature, and then mixing and grinding the resulting photocatalyst composite powder and a silicone resin, to obtain the coating composition of the present invention.
According to a preferred specific embodiment of the present invention, a sol-gel silicone resin and a photocatalyst composite powder in suitable proportions are mixed and optionally a solvent is added, followed by grinding, so as to obtain the coating composition of the present invention. The above-mentioned photocatalyst composite powder can be obtained by the process comprising the following steps:
(a) obtaining a white gel hydrate through hydrolysis of titanium tetrachloride;
(b) adding concentrated sulfuric acid into the resulting hydrate in a reactor, and stirring for 10-50 min, to obtain a titanium sulfate solution;
(c) sufficiently mixing the titanium sulfate solution, and stirring for 0.5-5 hrs at normal temperature;
(d) heating to 80-100° C., and reacting for 2-7 hrs at a constant temperature; and
(e) adding an ITO powder at a suitable ratio, stirring for 1-4 hrs for mixing, dripping 4-6 M aqueous sodium hydroxide solution, filtering, washing, and drying at room temperature, to obtain the photocatalyst composite powder (TiO2+ITO).
The present invention will be further described in detail through the following examples. It should be understood that the examples are merely used to exemplify the present invention, but not intended to limit the scope of the present invention. Any modification or alteration obvious to persons skilled in the art and made without departing from the spirit and principle of the present invention should fall within the scope of the present invention.
EXAMPLESIn the examples and comparative examples below, the percentages are weight percents (wt %), unless otherwise stated.
Example 1200 ml of a 3.9 M titanium tetrachloride solution was diluted with water to a total volume of 2000 ml, and then 500 ml (5 M) of aqueous ammonia was dripped, to generate a white titanium hydroxide precipitate, which was filtered, washed with deionizer water (200 ml×3) to remove the remaining water, to obtain titanium hydroxide [Ti(OH)4] as a white gel.
100-150 g of concentrated sulfuric acid (18M) was added to 250 g of the above-mentioned titanium hydroxide, and stirred for 30 min, to obtain a transparent and clear titanium sulfate solution. The titanium sulfate solution was placed in a reactor, 32.2 g of an aqueous SiO2 solution (20%) was added, stirred for 4 hrs at normal temperature, then heated to 100° C., and reacted for 2 hrs. 100 g of an aqueous ITO solution (10%) was added, the reaction was stirred at normal temperature for 2 hrs, to obtain a mixture.
600 ml (5 M) of an aqueous sodium hydroxide solution was dripped, then the resulting solution was adjusted to a neutral pH, and a resulting precipitate was filtered, washed, and dried at room temperature, to obtain a grey blue powder, which was detected through XRD to be a photocatalyst composite of an anatase type photocatalyst and ITO.
The resulting photocatalyst composite was added to a silicone resin (having a solid content of 27%) at a ratio (in weight) of the photocatalyst composite:resin=1:3, stirred, ground, dispersed, and applied onto a glass plate to form a coating having a thickness of 5 micrometers. A light transmittance measurement, organic (methylene blue) decomposition test, hydrophilic property test, and heat insulation test were conducted.
A blank glass plate and a coating were placed in a UV/visible/near infrared spectrometer (manufactured by JASCO Incorporation, Model V-570) respectively, to measure the light transmittance in the range of UV light to near infrared light. The test results are as shown in
(35±0.3) ml of methylene blue was added to a cylindrical test column having an inner diameter of 40 mm and a height of 30 mm, and then square glass with a side length of (6012) mm and having a coating was placed thereon. The coating was irradiated with UV light of (1.00±0.05) mW/cm2 for 6 hrs in total, and the decomposition rate of methylene blue was measured every 1 hr. The test results are as shown in
Taking a square glass having a side length of (100±2) mm with a coating as a test plate, 1 μL of water contacted with the test plate, an image is captured, and the contact angle was measured with a contact angle tester. The coating was irradiated with UV light of (1.0±0.1) mW/cm2, and the contact angle was measured once every 50 hrs. The test results are as shown in
A coating was placed at a position of about 20 cm below an infrared light bulb (PHILIPS Corporation), and a beaker containing 100 g of water was placed at a position of about 15 cm below the glass coating, and irradiated with the infrared light bulb, and the surface temperature was regularly measured with an infrared thermometer (TES series, TES Electrical Electronic Corp.) every 5 min. The test results are as shown in Table 1 below, and the surface temperature of the coating after 30-minutes of irradiation is as shown in Table 2 below.
Example 2200 ml of a 3.9 M titanium tetrachloride solution was diluted with water to a total volume of 2000 ml, and then 500 ml (5 M) of aqueous ammonia was dripped, to generate a white titanium hydroxide precipitate, which was filtered, washed with deionized water (200 ml×3) to remove the remaining water, to obtain titanium hydroxide [Ti(OH)4] as a white gel.
100-150 g of concentrated sulfuric acid (18M) was added to 250 g of the above-mentioned titanium hydroxide, and stirred for 30 min, to obtain a transparent and clear titanium sulfate solution. The titanium sulfate solution was placed in a reactor, 32.2 g of an aqueous SiO2 solution (20%) was added, stirred for 4 hrs at normal temperature, then heated to 100° C., and reacted for 2 hrs. 100 g of an aqueous ATO solution (15%) was added, the reaction was stirred at normal temperature for 2 hrs, to obtain a mixture.
600 ml (5 M) of an aqueous sodium hydroxide solution was dripped, then the resulting solution was adjusted to a neutral pH, and a resulting precipitate was filtered, washed, and dried at room temperature, to obtain a deep blue powder, which was detected through XRD to be a photocatalyst composite of an anatase type photocatalyst and ATO.
The resulting photocatalyst composite was added to a silicone resin (having a solid content of 27%) at a ratio (in weight) of the photocatalyst composite:resin=1:3, stirred, ground, dispersed, and applied onto a glass plate to form a coating having a thickness of 5 micrometers. A heat insulation test was conducted.
A coating was placed at a position of about 20 cm below an infrared light bulb (PHILIPS Corporation), and a beaker containing 100 g of water was placed at a position of about 15 cm below the glass coating, and irradiated with the infrared light bulb, and the surface temperature was regularly measured with an infrared thermometer (TES series, TES Electrical Electronic Corp.) every 5 min. The test results are as shown in Table 1 below, and the surface temperature of the coating after 30-minutes of irradiation is as shown in Table 2 below.
Comparative Example 1200 ml of a 3.9 M titanium tetrachloride solution was diluted with water to a total volume of 2000 ml, and then 500 ml (5 M) of aqueous ammonia was dripped, to generate a white titanium hydroxide precipitate, which was filtered, washed with deionized water (200 ml×3) to remove the remaining water, to obtain titanium hydroxide [Ti(OH)4] as a white gel.
100-150 g of concentrated sulfuric acid (18M) was added to 250 g of the above-mentioned titanium hydroxide, and stirred for 30 min, to obtain a transparent and clear titanium sulfate solution. The titanium sulfate solution was placed in a reactor, 32.2 g of an aqueous SiO2 solution (20%) was added, stirred for 4 hrs at normal temperature, then heated to 100° C., and reacted for 2 hrs. 100 g of an aqueous lanthanum hexaboride solution (10%) was added, the reaction was stirred at normal temperature for 1 hr, to obtain a mixture.
600 ml (5 M) of an aqueous sodium hydroxide solution was dripped, and a resulting precipitate was filtered, washed, and dried at room temperature, to obtain a gray blue powder, which was detected through XRD to be a photocatalyst composite of an anatase type photocatalyst and lanthanum hexaboride.
The resulting photocatalyst composite was added to a silicone resin (having a solid content of 27%) at a ratio (in weight) of the photocatalyst composite:resin=1:3, stirred, dispersed, and applied onto a glass plate to form a coating having a thickness of 5 micrometers. A heat insulation test (utilizing an infrared light bulb, PHILIPS Corporation) was conducted.
A coating was placed at a position of about 20 cm below an infrared light bulb, and a beaker containing 100 g of water was placed at a position of about 15 cm below the glass coating, and irradiated with the infrared light bulb, and the surface temperature was regularly measured with an infrared thermometer (TES series, TES Electrical Electronic Corp.) every 5 min. The test results are as shown in Table 1 below, and the surface temperature of the coating after 30-minutes of irradiation is as shown in Table 2 below.
Comparative Example 2A commercially available heat insulation paper (manufactured by Top Color Film Co. Ltd., trade name; SD series Top Colour) was attached to a glass surface, and placed at a position of about 20 cm below an infrared light bulb, and a beaker containing 100 g of water was placed at a position of about 15 cm below the glass attachment and irradiated with the infrared light bulb, and the surface temperature was regularly measured with an infrared thermometer (TES series, TES Electrical Electronic Corp.) every 5 min. The test results are as shown in Table 1 below, and the surface temperature of the attachment after 30 minutes of irradiation is as shown in Table 2 below.
It can be seen from the comparison of the results in Table 1 that, application of the coating having the coating composition of the present invention on the surface of the glass can effectively insulate heat.
It can be seen from the comparison between Examples 1 and 2 and Comparative Example 1 that the coating composition of the present invention can effectively reflect infrared light, resulting in a lower surface temperature on glass, thereby avoiding the risk of glass cracking.
It can be seen from the comparison between Examples and 2 and Comparative Example 2 that the coating composition of the present invention, comparing to heat insulation paper, provides a lower surface temperature on glass coating. The coating composition can be applied more easily than heat insulation paper, and is less likely to accumulate heat energy or generate heat convection, thereby providing a better heat insulation effect.
Claims
1. A coating composition, comprising a photocatalyst composite and a silicone resin, wherein the content of the photocatalyst composite is about 1 to 70 wt %, based on the total weight of the composition, and the photocatalyst composite comprises:
- (1) a heat insulation material selected from the group consisting of antimony tin oxide (ATO), indium tin oxide (ITO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium zinc oxide (GZO), and a combination thereof; and
- (2) a photocatalyst material selected from the group consisting of titanium dioxide, zinc oxide, strontium titanate, and tin oxide, and a combination thereof, wherein the content of the photocatalyst material is about 10 to 90 wt %, based on the total weight of the photocatalyst composite.
2. The coating composition according to claim 1, wherein the silicone resin is prepared through a sol-gel process.
3. The coating composition according to claim 1, further comprising an organic solvent.
4. The coating composition according to claim 1, wherein the heat insulation material is ATO or ITO.
5. The coating composition according to claim 1, wherein the content of the photocatalyst material is about 40 to 85 wt %, based on the total weight of the photocatalyst composite.
6. The coating composition according to claim 1, wherein the photocatalyst material is titanium dioxide.
7. The coating composition according to claim 1, wherein the photocatalyst composite has a particle size of about 2 to 100 nanometers (nm).
8. The coating composition according to claim 1, further comprising inorganic particulates selected from the group consisting of silica (SiO2), alumina (Al2O3), cadmium sulfide (CdS), zirconia (ZrO2), calcium phosphate (Ca3(PO4)2), and calcium oxide (CaO), and a mixture thereof.
9. An energy-saving material, comprising:
- a substrate; and
- a film formed from the coating composition according to claim 1 on at least one surface of the substrate.
10. The energy-saving material according to claim 9, wherein the film is formed by coating, spraying, or dipping the coating composition according to claim 1 on at least one surface of the substrate.
11. The energy-saving material according to claim 9, wherein the film has a pencil hardness of H or higher as measured according to JIS K5400 standard method.
Type: Application
Filed: Dec 8, 2011
Publication Date: Jul 5, 2012
Applicant:
Inventors: Sheng-Wei LIN (Kaohsiung), Mao-Jung Yeh (Kaohsiung)
Application Number: 13/314,323
International Classification: E04B 1/74 (20060101);
