JP2002331611A - Coated metal plate having excellent heat shielding properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated metal plate, in which a color tone can be selected from a dense color to a pale color, and a coated film having high heat reflectivity is formed. SOLUTION: The coated metal plate comprises the coated film containing a powder of a composite metal oxide which contains one type or more selected from V, Sr and Y, and Mn as heat shielding pigments and formed on the surface of the metal plate. As the pigment, it is preferred to use the powder which contains one or more types selected from a V-Mn oxide, an Sr-Mn oxide and a Y-Mn oxide as a main component. As the metal plate having the coated film formed to contain the heat shielding pigment, the plate which remains in coating pretreated or undercoating film formed, may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated metal plate for a building exterior material.

[0002]

2. Description of the Related Art In buildings such as warehouses, cool boxes, offices, factories, and barns, when there is a concern that the internal temperature will rise due to solar heat, the burden of cooling inside the building will be reduced and the temperature rise due to sunlight irradiation will be reduced. In order to suppress this, a white material or a metal exterior material having high heat reflectivity is used. As an exterior material having good heat reflectivity, a metal plate having a silvery white color such as a stainless steel plate or a Zn-Al-based plated steel plate, or a painted metal plate containing a white or metal powder is used.

[0003]

However, when a metal plate such as a stainless steel plate or a plated steel plate is used outdoors, reflected light is scattered to the surroundings to cause trouble to the neighborhood. Further, in the case of a plated steel sheet, the surface is oxidized with the lapse of time after the application, an oxide is generated, and the heat reflectance gradually decreases. Painted metal plates containing white or metal powder have excellent heat reflectivity, but have a low degree of freedom in color selection, making it difficult to cope with various designs required today. In particular,
Dark pigments that are added to give a calm appearance in harmony with the surroundings, ie, carbon black and Fe ₃
Since calcined pigments represented by O ₄ and CuO—Cr ₂ O ₃ systems have remarkable heat absorption, they are difficult to use for building exterior materials that require heat reflectivity. The present invention has been devised to solve such a problem, and provides a coated metal plate on which a coating film having a high heat reflection property can be selected from a dark color to a light color, and a coating film having high heat reflection is formed. The purpose is to:

[0004]

According to the present invention, there is provided a coated metal sheet having excellent heat shielding properties, wherein at least one of V, Sr, and Y as a heat insulating pigment is formed on the surface of the metal sheet to achieve the object. A coating film containing a powder of a composite metal oxide containing Mn was formed. As the heat-shielding pigment, it is preferable to use a powder containing one or more of V-Mn-based oxide, Sr-Mn-based oxide, and Y-Mn-based oxide as main components.
As a metal plate for forming a coating containing a heat-shielding pigment,
It may be one that has been subjected to the pre-coating treatment or one that has a base coat film formed thereon.

[0005]

The present inventors have investigated the factors that affect the thermal reflectivity of the coating film and found that the thermal reflectivity of the dark pigment mixed with the coating film has the greatest effect. Therefore, a heat-shielding pigment having a dark color and excellent heat reflection properties was searched for. The pigment dispersed in the coating film reflects visible light, out of electromagnetic waves such as sunlight, entering from the outside on the pigment surface, and imparts a predetermined color tone to the coating film surface. Near infrared rays, which are contained in sunlight and are called heat rays, are not visually perceived, but are reflected, absorbed, and transmitted on the pigment surface in the same manner as visible light. The absorption of this near infrared ray has an important effect on the temperature rise of the object. It is necessary to select a pigment having low near-infrared absorptivity and high reflectivity as a pigment having excellent heat reflectivity.

The present inventors have developed a dark-colored appearance,
Radiant pigments, i.e. visible light more than
Discover a pigment that absorbs and reflects near infrared rays to some extent
And disclosed in JP-A-11-80624. This face
Materials are InP, Mn_TwoO_Three, Mn _ThreeO_Four, Cu_TwoO, Cu
O, MoS_Two, CoFe_TwoO_Four, NiFe_TwoO_Four, MnTi
O_Three, MnCrO_Four, ZnCrO_FourAnd Ge
It is composed of at least one kind of semiconductor powder.

In the process of selecting the above-mentioned semiconductor powder, it is advantageous to use the characteristics of the electronic band-to-band transition and the refraction and reflection characteristics of the electromagnetic wave in order to make the appearance of the dark color and the near-infrared reflectivity compatible. That is, that is, since the wavelength of the absorption edge of the interband transition is determined by the size of the energy gap, the absorption edge has an energy gap near the boundary between visible light and near-infrared light, and is longer than the absorption edge. It has been found that a semiconductor must have a high refractive index in order to reflect an electromagnetic wave having a wavelength. Specifically, if the semiconductor has an energy gap of 0.6 to 2.0 eV and a refractive index of more than 2.0, the semiconductor has an absorption edge in a wavelength range of 0.6 to 2.0 μm. Long wavelength near infrared 40
%.

[0008] The inventors of the present invention based on the above findings of the invention.
In addition, heat-insulating pigments were further studied. The above semiconductor powder
Of which, Mn_TwoO_Three, Mn_ThreeO_FourAnd MnO manganic acid
All compounds are p-type with dark appearance and high near-infrared reflectivity
Semiconductor. As shown in the reflection spectrum of FIG.
Infrared reflectance is highest in MnO and MnO is highest._ThreeO_Four> Mn_TwoO_Three>
MnO_Two, The reflectivity decreases. Mn_ThreeO_FourIs exactly
MnO_Two・ 2MnO, Mn _TwoO_ThreeIs MnO_Two· Expressed in MnO
The higher the proportion of MnO included, the closer the near-infrared reflectivity
It turned out to be higher.

[0009] Therefore, as a result of studying a composite metal oxide composed of MnO as a basic structure and composited with various metal elements, V,
It has been found that a composite oxide with Mn containing at least one of Y and Sr can be a pigment having a dark appearance and excellent near-infrared reflection properties. The use of these compounds makes it possible to form a coated metal plate with excellent heat shielding properties from dark shades such as black, dark brown and dark blue to various white tones by mixing with other white pigments, light colored pigments and colored pigments. Manufacturing has become feasible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The more preferred composition of the composite metal oxide of the present invention is the following composition range in terms of the element ratio contained in the pigment. In the case of a V—Mn-based oxide, V: 25 to 4
2% by mass, Mn: 26 to 51% by mass, O: The balance is O. In the case of a Sr—Mn-based oxide, Sr: 37 to 54
% By mass, Mn: 19 to 35% by mass, O: balance. In the case of a Y—Mn-based oxide, Y: 35 to 52% by mass;
Mn: 20 to 35% by mass, O: composition of the remainder. As a specific example, Mn ₂ V ₂ O ₇ , a V—Mn-based oxide, has a visible light reflectance of 7% and a deep brown color tone, but a near-infrared reflectance of 63%. Sr of Sr-Mn oxide
MnO ₃ has a black color tone and a near-infrared reflectance of 61%
It is. YMnO ₃ of the Y—Mn-based oxide has a dark blue color tone and a near-infrared reflectance of 50%.

The near-infrared reflectance defined here is based on JIS
A5759 using spectral distribution Iramuda _i of solar radiation according to,
The target wavelength range is limited to 800 to 2100 nm, and is a number calculated by the following equation.

[0012]

The composite metal oxide containing at least one of V, Sr and Y and Mn includes Al, Si, Ca, Fe and Ba.
May be contained in an amount of 0 to 5% by mass. These metals are V,
Even if one or more of Sr and Y and Mn-containing complex metal oxide crystals are present as impurities in the form of substitution-type or interstitial-type solid solutions, etc., there is almost no effect on the near-infrared reflection characteristics of the pigment. . These impurities may be inevitably mixed, but by adding them positively, it is possible to generate impurity levels and change the color.

To the coating film of the present invention, a commonly used pigment is mixed and added together with one or more of V, Sr, and Y and a composite metal oxide containing Mn to obtain a desired color tone. Can be adjusted. However, dark pigments such as black, dark brown and dark blue to be incorporated in the coating film include V, S of the present invention.
It is necessary to note that a composite metal oxide containing at least one of r and Y and Mn is used and does not contain carbon black or the like, which is a dark pigment having a near-infrared reflectance of less than 20%. Pigments to be mixed and added are more preferably
White pigments such as TiO ₂ and ZnO, JP-A-11-8062
The semiconductor powder described in Japanese Patent Application Publication No. 4 (1994), a light-colored pigment such as yellow, and a metal powder such as aluminum and stainless steel are used. Since these pigments alone have a near-infrared reflectance of 50% or more, the addition of these pigments does not lower the heat-shielding property aimed at by the present invention.

The compounding amount of the heat-shielding pigment is selected in such a range that the coloring and infrared reflection effect can be obtained by adding the pigment and that the physical properties of the coating film are not impaired. Specifically, the content is preferably 3 to 60% by mass of the coating film. If the amount is less than 3% by mass, sufficient near-infrared reflectivity cannot be obtained. If the amount exceeds 60% by mass, the cohesive strength of the coating film is reduced and the coating film performance is deteriorated. The particle size of the heat-shielding pigment is preferably about の of the wavelength at which reflection and refraction are desired to occur according to Fresnel's law, and specifically 0.1 to 10 μm. If it is less than 0.1 μm, it becomes substantially transparent to visible light and near infrared rays, and the effect of adding a pigment cannot be obtained. Also, 10 μm
Is exceeded, the above-mentioned compounding amount for ensuring the performance of the coating film is used as a reference, so that the surface area of the pigment involved in reflection is reduced and the reflection efficiency is greatly reduced.

As the base main resin of the paint, a resin blended in a usual paint can be used, and the kind of the resin is not particularly limited. Specifically, alkyd resin,
A polyester resin, a silicone resin, a silicone-modified polyester resin, an acrylic resin, a silicone-modified acrylic resin, an epoxy resin, a fluororesin, a chlorine resin, and the like are used, and may be used in combination with a crosslinking resin.

Various additives can be added to the paint for the purpose of imparting various functions to the coating film. For example,
Polytetrafluoroethylene, polyethylene wax, polycarbonate, or the like can be added to impart lubricity to the surface of the coating film. In order to prevent scratches on the coating film, glass beads, glass fibers, ceramics such as silicon carbide, mica, polyacrylonitrile beads, acrylic polymer beads, nylon beads and the like can be added. Further, without using a solvent, a coating film can also be formed by kneading a heat-shielding pigment into a thermoplastic resin such as polyethylene resin, polypropylene resin, or polyethylene terephthalate resin, and heat-sealing or injection molding the metal plate. .

[0018] The coating original plate includes ordinary steel sheet, surface-treated steel sheet,
A plated steel plate, a stainless steel plate, an aluminum plate, an aluminum alloy plate, or the like can be used. As the galvanized steel sheet, electro-galvanized steel sheet, hot-dip galvanized steel sheet, hot-dip 5% Al-Zn coated steel sheet, hot-dip 6% Al-3% Mg-
Zn-plated steel sheet, hot-dip 55% Al-Zn coated steel sheet, hot-dip aluminum coated steel sheet, hot-dip galvanized stainless steel sheet,
Hot-dip aluminum-plated stainless steel sheets and the like can be mentioned. Also, there is no limitation on the type of stainless steel sheet, and ferritic stainless steel sheet, austenitic stainless steel sheet,
A martensitic stainless steel sheet, a duplex stainless steel sheet, or the like can be used.

In order to impart sufficient adhesion between the coating film and the metal plate, it is preferable to apply a pre-coating treatment to the surface of the metal plate prior to the formation of the coating film. As the pre-coating treatment, alkali degreasing to clean the surface, degreasing with a surfactant, solvent degreasing, or washing or pickling in which these are combined are performed as necessary to replace Ni, Co, Fe, etc. After performing precipitation-type surface conditioning treatment or phosphate treatment, reaction-type chromate treatment or coating-type chromate treatment, or application with a treatment agent in which at least one of a zirconium compound, a manganese compound, and an organic resin component is mixed with fluorotitanic acid Type processing may be performed.

For applications used in a relatively corrosive environment such as a beach area or an industrial area, the adhesiveness to the base metal plate and the corrosion resistance of the base metal plate are provided under a resin coating containing a heat-insulating pigment. It is recommended to apply a primer coat containing a rust-preventive pigment to improve. It is also possible to add an appropriate amount of the heat-shielding pigment of the present invention to the undercoat film. The addition makes it possible to capture near-infrared light transmitted through the top coat and reflect it on the undercoat, thereby improving the reflectivity of the coated metal plate.

[0021]

EXAMPLE A hot-dip 55% Al-Zn alloy-plated steel sheet having a thickness of 0.5 mm was used as a base metal sheet.
After being degreased with an alkaline solution containing sodium hydroxide as a main component, it was washed away with warm water. Next, a coating type chromate treating agent was applied and dried to form a chromate film having a chromium adhesion amount of 40 mg / m ^{2 on} the surface of the metal plate. Some test specimens have epibis epoxy resin as the main resin and melamine resin as the cross-linking agent, and have a weight ratio of 8
Mixed paint base at a ratio of 5/15, 15PWC% of strontium chromate, a TiO ₂ 20PWC%,
A coating containing 12 PWC% of barium sulfate was applied by a roll coater to a dry coating of 5 μm, and dried and cured.

Next, a heat-shielding pigment and a comparative pigment are mixed at various ratios with a resin-based paint containing a mixed resin solution of vinylidene fluoride resin / methyl methacrylate resin (mass ratio 80/20), The coating was prepared by dispersing in a roll kneader. Table 1 shows the main components and the average particle size and color tone of the heat-shielding pigment and the comparative pigment used,
Table 2 shows the element ratio of the heat-shielding pigment.

[0023]

[0024]

Various pigments were mixed in the proportions shown in Table 3. The obtained coating did not settle or agglomerate the heat-insulating pigment even after being left for a long time, and had good storage stability. Apply the paint to the metal plate using a roll coater,
After heating and drying at 50 ° C. for 1 minute, it was immediately cooled with water to form a coating film having a thickness of 20 μm. The prepared coated metal plate was measured for solar reflectance according to JIS A5759, and the target wavelength range was specified to be 800 to 2100 nm, and near-infrared reflectance was determined in the same manner as the solar reflectance. The results are shown in Table 3 together with the coating composition.

[0026]

As can be seen from Table 3, the coated metal sheet of the present invention has a near-infrared reflectance exceeding 50% and excellent heat shielding properties despite its appearance of black, dark brown and dark blue. You can see that. On the other hand, Comparative Examples 1, 2, and 3 having similar shades using a conventionally used pigment have a near-infrared reflectance of 30% or less. FIG. 2 shows the spectral reflection spectra measured from the coating surfaces of Example 3 and Comparative Example 1, both of which are painted metal plates having a black appearance. It can be seen that the reflectances in the ultraviolet and visible light regions are almost the same, but the reflectance in the near infrared region has a large difference of 61% and 7%.

[0028]

As described above, the coated metal sheet of the present invention contains a composite metal oxide powder having a high near-infrared reflectivity while having a dark appearance, so that The near infrared rays of the radiated sunlight are efficiently reflected, and the transmission of the thermal energy of the sunlight to the painted metal plate is suppressed. Therefore, when used for a roof or an outer wall of a building, the surface temperature of the coating film can be maintained at a state close to the outside air temperature, the rise in the indoor temperature can be suppressed, and the cooling energy can be reduced. In addition, by using this heat-shielding coated metal plate, the thickness of the heat insulating layer such as glass wool or urethane foam can be reduced, so that the effective internal volume of the building increases.

[Brief description of the drawings]

FIG. 1 Spectral reflection spectra of various manganese oxide powders with different oxidation numbers

FIG. 2 Spectral reflection spectra measured from the coating surfaces of Example 3 and Comparative Example 1.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Enya 7-1 Takaya Shinmachi, Ichikawa City, Chiba Prefecture Nisshin Steel R & D Co., Ltd. (72) Inventor Minoru Kiyozuka 7-1 Takaya Shinmachi, Ichikawa City, Chiba Prefecture Sun 4D075 CA13 CA17 CA25 CA33 DA03 DA06 DB02 DB04 DB05 DB07 DC01 EB13 EB15 EB16 EB22 EB32 EB33 EB35 EB36 EB43 EC02 4F100 AA33B AB01A AB03 AK36 AK53 BA02 BA07 CC00B EJN46

Claims (2)

[Claims] 1. A method according to claim 1, wherein V, V,
A coated metal plate excellent in heat insulation, wherein a coated film containing a powder of a composite metal oxide containing at least one of Sr and Y and Mn is formed. 2. The heat-shielding pigment is a V—Mn-based oxide, Sr
The coated metal sheet having excellent heat shielding properties according to claim 1, which is a powder containing at least one of a -Mn-based oxide and a Y-Mn-based oxide as a main component.