JP2011005430A - Method for forming solar heat absorbing coating film and solar heat absorption material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a solar heat absorbing coating film which is capable of anticipating the remarkable effect in saving of energy by reducing the air conditioning cost or aiming at the indoor heat insulation, wherein the solar coating film is colorable and also has a fine appearance.SOLUTION: The method for forming the solar heat absorbing coating film comprises steps of applying a lower layer coating film of which the reflectance of solar radiation as a coating film itself at a wavelength of 780-2,300 nm is 30% or less on the surface of the substrate using a coating in which 1-10 mass% of a porous pigment such as carbon black and the like having high absorption in a near infrared ray region is combined, then laminating the upper layer coating film of which the permeability of solar radiation is 30% or more as a coating film itself at a wavelength of 780-2,300 nm on the surface of the lower layer coating film using a coating in which 1-15 mass% of a pigment having high near infrared permeability such as an organic pigment and the like is combined to form the solar heat absorbing coating film of which the reflection of solar radiation at a wavelength of 780-2,300 nm is 50% or less. Also the solar heat absorption coating film is obtained.

Description

  The present invention is used for various materials such as metal, glass, concrete, plastic, wood, etc., and effectively absorbs solar heat and forms a solar heat-absorbing coating film that has low heat radiation loss and excellent heat retention and weather resistance. The present invention relates to a method and a solar heat absorbing material.

  Conventionally, solar thermal energy utilization technology has attracted attention. Examples of such technology include transition metal carbides belonging to Group IV of the periodic table such as TiC, ZrC, and HfC, or a mixture of this carbide and aluminum. There has been proposed a solar heat-absorbing heat-retaining coating material obtained by kneading the above into a binder fluidized with a volatile solvent or a cream-like binder for various coatings (see, for example, Patent Document 1). Patent Document 1 also describes that a pigment may be added to the binder. Furthermore, Patent Document 1 also describes that a planar body can be formed by applying the above-described coating material to another article or skin. Therefore, when coated or coated, it exhibits a large absorption performance in the wavelength range of 0.3 to 2.0 μm of the solar radiation spectrum, which is a characteristic of transition metal carbides belonging to Group IV of the periodic table. In addition, it is said that a solar heat selective absorption heat retaining effect that acts to reduce the radiation loss of heat by suppressing the emissivity in the infrared region of 2.0 μm or more can be exhibited.

Japanese Patent Laid-Open No. 01-212468

  However, as in the coating material of Patent Document 1, transition metal carbides belonging to Group IV of the periodic table such as TiC, ZrC, HfC, or the like and mixtures of these carbides and aluminum are used as components in the paint. However, the solar heat absorption effect is not satisfied, and the coloring range is limited, which is not practical as a coating film.

  In view of the above problems, the present invention provides a method for forming a solar heat-absorbing coating film and a solar heat-absorbing material that effectively absorbs solar heat, reduces heat loss due to light irradiation, retains heat, can be colored, and has an excellent appearance. It is for the purpose.

  As a result of repeating various test studies in order to solve the above problems, the present inventors have found that 1% by mass of a pigment having a high light absorption rate in the near-infrared region with a porous pigment such as carbon black on the surface of the substrate. A coating material in which a lower coating film is applied using a coating material blended in an amount of 10 to 10% by mass, and then a pigment having a high light transmittance in the near-infrared region such as an organic pigment is blended on the surface of the lower coating layer. It was found that a solar heat absorbing coating film that effectively absorbs solar heat, has little loss due to heat radiation, and has excellent heat retention and weather resistance can be obtained by forming an upper layer coating film using The present invention was completed based on the above.

  That is, in the method for forming a solar heat absorbing coating film according to the present invention, a lower layer coating film having a solar reflectance of 30% or less at a wavelength of 780 to 2300 nm is applied to the substrate surface, and then the lower layer coating film is applied. A solar heat absorbing coating film having a solar reflectance at a wavelength of 780 to 2300 nm of 50% or less by laminating an upper layer coating film having a solar transmittance of 30% or more at a wavelength of 780 nm to 2300 nm on the film surface. It is characterized by forming.

  Moreover, the solar heat absorption material which concerns on this invention is a base-material surface with the lower layer coating film whose solar reflectance in the coating-film single-piece | unit in the wavelength of 780 nm-2300 nm is 30% or less, and the coating-film single body in the wavelength of 780 nm-2300 nm. A solar heat-absorbing coating film having a solar radiation transmittance of 30% or more, and a solar heat-absorbing coating film sequentially laminated, and the solar reflectance at a wavelength of 780 nm to 2300 nm of the solar heat-absorbing coating film is 50% or less. Features.

  According to the present invention, by forming a coating film with high infrared transparency in the upper layer and using a pigment such as carbon black in the lower layer, the appearance can provide the color of the upper layer, and the lower layer can absorb infrared rays Therefore, it is possible to increase the solar radiation absorption rate as a coated film.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  In the present invention, for example, a coating film having a wavelength of 780 nm to 2300 nm is used on the surface of the base material by using a paint containing 1 to 10% by mass of a pigment having a high absorption rate in the near infrared region with a porous pigment such as carbon black. Apply a lower layer coating film having a solar reflectance of 30% or less as a single unit, and then use a coating composition containing, for example, 1 to 15% by mass of a pigment having high near-infrared transmittance such as an organic pigment on the surface of the lower layer coating film Then, by laminating an upper layer coating film having a solar radiation transmittance of 30% or more at a wavelength of 780 nm to 2300 nm, a solar heat absorbing coating film having a solar reflectance of 50% or less at a wavelength of 780 nm to 2300 nm is formed. A method for forming a solar heat-absorbing coating film is used.

  Further, according to the present invention, using the above-described method, the lower surface coating film having a solar reflectance of 30% or less at a wavelength of 780 nm to 2300 nm on the substrate surface and a wavelength of 780 nm to 2300 nm A solar heat absorbing coating film in which the solar transmittance of the coating film alone is 30% or more and an upper layer coating film are sequentially laminated, and the solar reflectance at a wavelength of 780 nm to 2300 nm of the solar heat absorbing coating film is 50% or less. Thus, a solar heat absorbing material can be obtained.

  Here, in the present invention, the solar reflectance and the solar transmittance in the wavelength range of 780 nm to 2300 nm are defined. The wavelength range is a wavelength of light in a so-called near infrared region, and the near infrared ray is absorbed by the substance. This is because of the wavelength at which thermal action occurs.

  In addition, the reason why the solar reflectance of the coating film alone at a wavelength of 780 nm to 2300 nm of the lower layer coating film was set to 30% or less is that the lower layer coating film efficiently absorbs heat.

  The reason why the solar transmittance of the coating film alone at the wavelength of 780 nm to 2300 nm of the upper layer coating film is set to 30% or more is to efficiently transmit light to the lower layer coating film.

  Furthermore, the solar heat absorption coating film formed using the method for forming a solar heat absorption coating film according to the present invention has a solar reflectance (specified in JIS K 5602) of 50 at a wavelength of 780 nm to 2300 nm. % Or less. This is because the solar heat-absorbing coating efficiently absorbs heat, and the coloring by the pigment in the coating is ensured to improve the appearance.

  The lower layer coating material and the upper layer coating material used for forming the lower layer coating film and the upper layer coating film of the present invention include a resin, a pigment and a solvent as essential components, and, for example, extender pigments, antifoaming agents, and curing accelerators. , Various additives such as dispersants, antioxidants and fungicides are appropriately blended.

  The type and form of the paint are not particularly limited, and examples of the kind of paint include thermosetting paint, thermoplastic paint, room temperature drying paint, room temperature curable paint, active energy ray curable paint, and the like. Can do. The form of the paint can be applied to any of solvent-type paints, water-based paints, non-water emulsion paints, solvent-free paints, powder paints, and the like.

  A porous pigment is blended in the lower layer paint of the present invention. Examples of the porous pigment used in the lower layer paint include pigments such as carbon black, resin beads, and silica. Among these, carbon black is particularly preferable.

  In addition, the amount of the porous pigment blended into the lower layer paint is preferably 1% by mass to 10% by mass with respect to the entire solid content of the lower layer paint in consideration of the stability of the paint.

Furthermore, the specific surface area of the porous pigment is desirably 400 m ² / g or less in order to efficiently absorb infrared rays and capture it inside the pigment. The specific surface area of the porous pigment in the present invention can be measured using the BET method.

  Useful organic pigments as pigments used in the paint for forming the upper coating film of the present invention include, for example, monoazo, disazo, lake azo, β-naphthol, naphthol AS, benzimidazolone, condensed disazo, azo metal complex pigments, and the like. Polycyclic pigments such as phthalocyanine, quinacridone, perylene, perinone, thioindigo, anthrone, anthraquinone, flavantron, indanthrone, isoviolanthrone, pyranthrone, dioxazine, quinophthalone, isoindolinone, isoindoline and diketopyrrolopyrrole pigments Or carbon black. Of these, phthalocyanine blue, quinacridone magenta, isoindoline, and diketopyrrolopyrrole are particularly preferable as the organic pigment.

  Examples of the inorganic pigment used in the paint for forming the upper layer coating film of the present invention include titanium dioxide, zinc sulfide, iron oxide, chromium oxide, ultramarine, nickel antimony titanium oxide, chromium antimony titanium oxide, cobalt oxide and cobalt. And aluminum mixed oxide, bismuth vanadate, and mixed pigments. Of these, bismuth vanadate is particularly preferable as the inorganic pigment.

  The pigments used in the above-described paint for forming the upper layer coating film can be used singly or in combination of two or more.

  The paint resin used as the base of the paint of the present invention is not particularly limited as long as it is commonly used for paints. For example, acrylic resin, alkyd resin, urethane resin, polyester resin, silicone-modified polyester resin, There are silicone-modified acrylic resin, epoxy resin, polycarbonate resin, silicate resin, chlorine resin, fluorine resin, etc., and as necessary, for crosslinking of amino resin such as melamine resin, isocyanate, or block isocyanate as curing agent A resin may be included.

  The other additives are not particularly limited. For example, extender pigments such as titanium dioxide, barium sulfate, and calcium carbonate, matting agents such as silica and alumina, antifoaming agents, leveling agents, and anti-sagging agents. And surface additives, viscosity modifiers, dispersants, ultraviolet absorbers, conventional additives such as wax, and the like.

  The other solvent is not particularly limited as long as it is generally used for paints. For example, aromatic hydrocarbons such as toluene, xylene, Solvesso 100, Solvesso 150, ethyl acetate, butyl acetate, etc. And esters such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and other aliphatic solvents such as mineral spirits and water. These are appropriately selected in consideration of solubility, evaporation rate, safety and the like. These may be used alone or in combination of two or more.

  The coating composition used for forming the coating film of the present invention can be produced, for example, as follows. Prepare a dispersion paste of resin and pigment using a machine generally used for pigment dispersion such as roller mill, paint shaker, pot mill, disper, sand grind mill, etc., and add resin, various additives, organic solvent, curing A coating composition is obtained by adding an agent, a catalyst and the like.

  The coating method of the coating composition is not particularly limited. For example, generally used coating methods such as dipping, brush, roller, roll coater, air spray, airless spray, curtain flow coater, roller curtain coater, die coater, etc. Etc. These are appropriately selected according to the purpose of use of the substrate.

  The substrate on which the solar heat absorbing coating film of the present invention is formed is not particularly limited, and examples thereof include metal substrates, plastic substrates, and inorganic material substrates. Examples of the metal substrate include an aluminum plate, an iron plate, a galvanized steel plate, an aluminum galvanized steel plate, a stainless steel plate, and a tin plate. Examples of the plastic base material include base materials such as acrylic, vinyl chloride, polycarbonate, ABS, polyethylene terephthalate, and polyolefin. As an inorganic material base material, the ceramic base material described in JIS A 5422, A 5430, etc., a glass base material, etc. can be mentioned, for example.

  The base material may be subjected to surface treatment for adhesion or rust prevention.

  Hereinafter, the coating material used for an Example and a comparative example is demonstrated. Hereinafter, unless otherwise specified, [%] and [part] are based on mass.

Example 1
In Example 1, carbon black (Colombian Carbon Co., “R14”) 1.5 parts, barium sulfate 17 parts, calcium carbonate 21 parts, epoxy resin (JER Co., “S40EP”) 40 parts, xylene 20 parts Then, 0.5 part of an antifoaming agent (manufactured by Mitsubishi Rayon Co., Ltd., “LR611”) was kneaded with a roller mill for 30 minutes to obtain a coating for forming a lower layer coating film. The obtained lower layer paint is spray-coated on a steel plate (150 × 50 × 0.3 mm) so that the film thickness after curing is 100 μm, and dried under an atmosphere of 23 ° C. for 24 hours to form a lower layer coating film. It was. On this lower layer coating film, 3 parts of phthalocyanine blue (manufactured by Dainichi Seika), 2 parts of quinacridone magenta (manufactured by Ciba Specialty Chemicals, “CR759D”), isoindoline (manufactured by Ciba Specialty Chemicals, “2GLTE”) 2 parts, 57 parts of fluororesin (manufactured by Asahi Glass Co., Ltd., LF800), 35.7 parts of mineral spirits, 0.3 part of antifoaming agent (“SN359” manufactured by San Nopco Co., Ltd.) were kneaded for 30 minutes with a roller mill. Thus, a paint for forming an upper coating film was obtained. The obtained coating material for forming the upper coating film was spray-coated so that the film thickness after drying was 50 μm, and was dried in an atmosphere at 23 ° C. for 3 days to obtain a test specimen.

(Example 2)
The lower layer paint was tested in the same manner as in Example 1 except that 1.5 parts of “Special Black 6” (manufactured by Degussa Evonik) was used instead of 1.5 parts of “R14” as carbon black. Got the body.

(Example 3)
The lower layer paint was tested in the same manner as in Example 1 except that 1.5 parts of “MONA1300” (Cabot Corporation) was used instead of 1.5 parts of “R14” as carbon black. Got the body.

Example 4
A test specimen was obtained in the same manner as in Example 1 except that 2 parts of bismuth vanadate (manufactured by Clariant Japan Co., Ltd.) was used instead of 2 parts of isoindoline.
(Example 5)
In the lower coating, 1.0 part of carbon black, 12.8 parts of barium sulfate, 15.7 parts of calcium carbonate, and 10 parts of titanium dioxide (“CR95” manufactured by Ishihara Sangyo Co., Ltd.) were further added. Except for this, a specimen was obtained in the same manner as in Example 1.

(Example 6)
A test specimen was obtained in the same manner as in Example 1 except that 2 parts of diketopyrrolopyrrole (manufactured by Ciba Specialty Chemicals) was used instead of 2 parts of quinacridone magenta in the upper layer paint.

(Example 7)
In the upper coating, the test specimen was prepared in the same manner as in Example 1 except that the mineral spirit was 30.7 parts and 5 parts of titanium dioxide (“CR95” manufactured by Ishihara Sangyo Co., Ltd.) was further added. Got.

(Example 8)
A test specimen was obtained in the same manner as in Example 1 except that 15 parts of barium sulfate, 18 parts of calcium carbonate, and 5 parts of titanium dioxide were further added in the lower layer coating.

Example 9
A test specimen was obtained in the same manner as in Example 8 except that 1.0 part of carbon black and 18.5 parts of calcium carbonate were used in the lower layer coating.

(Example 10)
A test specimen was obtained in the same manner as in Example 1 except that the lower layer coating was changed to 11.0 parts carbon black and 5.5 parts calcium carbonate.

(Comparative Example 1)
A test specimen was obtained in the same manner as in Example 5 except that carbon black, barium sulfate and calcium carbonate were not added to the lower layer coating, except that 59.5 parts of mineral spirit and 20 parts of titanium dioxide were used. It was.

(Comparative Example 2)
Comparative Example 1 except that in the upper coating, 2 parts of quinacridone magenta, 2 parts of isoindoline were used, 10 parts of titanium dioxide and 2 parts of Bengala were used, and the mineral spirit was 27.7 parts. A test body was obtained in the same manner as above.

(Comparative Example 3)
Example 1 except that in the upper layer coating, 2 parts of quinacridone magenta, 2 parts of isoindoline were used, 10 parts of titanium dioxide and 2 parts of Bengala were used, and the mineral spirit was 27.7 parts. A test body was obtained in the same manner as above.

(Comparative Example 4)
Titanium oxide 28 parts, ZrC 7.5 parts (manufactured by Mitsuwa Chemicals Co., Ltd.), Al powder 4.5 parts (manufactured by Kanto Chemical Co., Ltd.), and isocyanate curable resin ACRYDIC A-848-RN ( (Made by DIC Corporation)
After 25 parts and 30 parts of mineral spirit were kneaded, 5 parts of isocyanate TSC100 (Asahi Kasei Chemicals Corporation) was added to obtain a paint for forming a coating film. The obtained coating material was coated on a steel plate (150 × 50 × 0.3 mm) with a roller so that the film thickness after curing was 100 μm, and dried in an atmosphere at 23 ° C. for 24 hours to obtain a test body.

  About the obtained specimen, the solar reflectance of the lower layer coating alone, the solar transmittance of the upper layer coating alone, the solar reflectance of the entire laminated solar heat absorbing coating (the solar reflectance of the coating as a coating specification) Rate) and coating film surface temperature. Table 1 shows the paint components and the results of the test. Each test was performed according to the following method, and the results were evaluated.

<Solar reflectance>
In accordance with JIS K 5602, spectral reflectance up to a wavelength of 780 nm to 2300 nm was measured using a spectrophotometer: UV-3100PC manufactured by Shimadzu Corporation.

<Solar radiation transmittance>
A smooth coating of PTFE (polytetrafluoroethylene) with an upper layer coating applied to a uniform thickness, dried for 24 hours in an atmosphere at 23 ° C. to a dry film thickness of 50 μm, and peeled off from PTFE Was used as a test specimen. Using the spectrophotometer: UV-3100PC, the prepared test body was measured for spectral transmittance from a wavelength of 780 nm to 2300 nm.

<Coating surface temperature>
Approximate solar light conforming to JIS C 8912 CLASS C so that the specimen is placed in a sealed environment that is not affected by the ambient temperature, and the amount of light received at the light receiving surface of the specimen is 800 W / m ^2. Light irradiation was performed using an irradiation tester (manufactured by Toyo Seisakusho). The temperature of the coating film surface at that time was measured. The results are shown in Table 1.

<Stability of paint>
The viscosity of the paint immediately after preparation of the lower paint and after storage of the lower paint for 1 month at room temperature is measured at 20 ° C. using a B-type viscometer, and the stability of the lower paint is expressed by the following formula (1). The change rate Δη (%) of the paint viscosity expressed was evaluated. In the following formula (1), the viscosity of the lower layer coating immediately after preparation is η ₀ , and the viscosity of the lower layer coating after storage at room temperature for 1 month is η ₁ .
Δη (%) = (η ₁ −η ₀ ) × 100 / η ₀ (1)

The evaluation criteria are as follows.
A: Absolute value of change rate of viscosity after storage for 1 month at room temperature is within 5% ○: Absolute value of change rate of viscosity after storage for 1 month at room temperature is more than 5% and 10% or less ×: 1 at normal temperature The absolute value of the rate of change in viscosity after storage for months exceeds 10%

  As shown in Table 1, in each of Examples 1 to 10, the color of the pigment contained in the upper layer paint is sufficiently expressed, and the solar reflectance as a coating specification is suppressed to 50% or less. It can be seen that the solar radiation absorption rate can be increased. As a result, the temperature of the surface of the test specimen was also high.

  Further, Example 10 in which the content of the porous pigment blended in the lower layer coating exceeds 10% by mass is slightly more stable than the other Examples 1 to 9 in which the content of the porous pigment is 10% by mass or less. Tended to be inferior.

  On the other hand, the solar radiation reflectance in the lower layer coating material alone exceeds 30%, the solar radiation reflectance in the lower layer coating material alone exceeds 30%, and the solar radiation transmittance in the upper layer coating material alone is less than 30%. Comparative Example 2, Comparative Example 3 in which the solar transmittance of the upper layer coating film alone is less than 30%, Comparative Example having no lower layer coating film, and the solar transmittance of the upper layer coating film alone is less than 30% In all cases, the solar reflectance as a coating specification was as high as more than 50%, and as a result, the temperature of the surface of the test specimen was all low.

As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

Claims (12)

  On the surface of the base material, a lower layer coating film having a solar reflectance of 30% or less at a wavelength of 780 nm to 2300 nm is applied, and then the surface of the lower layer coating film is coated with a coating film alone at a wavelength of 780 nm to 2300 nm. Formation of a solar heat absorbing coating film characterized by forming a solar heat absorbing coating film having a solar reflectance of 50% or less at a wavelength of 780 nm to 2300 nm by laminating an upper layer coating film having a solar transmittance of 30% or more. Method.   The method for forming a solar heat absorbing coating film according to claim 1, wherein a porous pigment is blended in a paint used for forming the lower layer coating film, and an inorganic pigment is used as the porous pigment.   The method for forming a solar heat absorbing coating film according to claim 1 or 2, wherein a porous pigment is blended in a paint used for forming the lower layer coating film, and carbon black is used as the porous pigment.   4. The solar heat-absorbing coating film according to claim 2, wherein a blending amount of the porous pigment is 1% by mass to 10% by mass with respect to the entire coating material used for forming the lower layer coating film. Forming method. The method for forming a solar heat absorbing coating film according to claim 2, wherein the porous pigment has a specific surface area of 400 m ² / g or less.   One or two selected from the group consisting of phthalocyanine blue, quinacridone magenta, isoindoline, diketopyrrolopyrrole, and bismuth vanadate yellow by blending a pigment into the paint used for forming the upper layer coating film. It is a pigment | dye of a seed | species or more, The formation method of the solar heat absorption coating film of any one of Claims 1-5 characterized by the above-mentioned. A lower layer coating film having a solar reflectance of 30% or less at a wavelength of 780 nm to 2300 nm and an upper layer coating having a solar transmittance of 30% or more at a wavelength of 780 nm to 2300 nm on the substrate surface. A solar heat-absorbing coating film that is laminated sequentially,
The solar heat absorbing material, wherein the solar heat absorbing coating film has a solar reflectance of 50% or less at a wavelength of 780 nm to 2300 nm.   The solar heat absorbing material according to claim 7, wherein the lower layer coating film includes a porous pigment, and the porous pigment is an inorganic pigment.   The solar heat absorbing material according to claim 8, wherein the inorganic pigment is carbon black.   10. The solar heat absorbing material according to claim 8, wherein the porous pigment is blended in an amount of 1% by mass to 10% by mass in a paint used for forming the lower layer coating film. 11. The solar heat absorbing material according to claim 8, wherein a specific surface area of the porous pigment is 400 m ² / g or less. The upper layer coating film includes one or two or more pigments selected from the group consisting of phthalocyanine blue, quinacridone magenta, isoindoline, diketopyrrolopyrrole and bismuth yellow vanadate. The solar heat absorption material of any one of -11.