JPH11100530A - Light reflecting coating composition and coated product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating material forming a film which reflects visible light as well as nearinfrared light at a high reflectivity by blending ZnAl2 O4 powder. SOLUTION: The ZnAl2 O4 powder has a particle size of pref. 0.01-100 μm. The blended amt. is pref. 30-90 wt.% based on the nonvolatile coating component. As a white pigment, ZnAl2 O4 can be used solely as well as together with TiO2 and/or ZnO. Other inorg. and/or org. pigments can be mixed together if a white type or pale-colored type pigment is required. Metallic flakes can be added in case the coating material is used for a part where some metallic touch is permissible. The compsn. can be applied to an org. solvent system, a water-borne system or a powder system regardless of natural drying type, heat-drying type or heat-melting Type. Any kind of resin can be employed. It can also be applied to a coating material which uses an inorg. polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition and a coated product whose coating film reflects visible light and near infrared rays at a high rate.

[0002]

2. Description of the Related Art Light-reflecting properties are required, such as the outer walls of buildings, such as warehouses and cool boxes, in which the rise in internal temperature due to sunlight hitting the outer walls is suppressed, and the ceilings and walls in rooms that use indirect lighting for lighting. The parts that do not like the metallic texture and the glare of specular light are painted with white paint on the surface to reflect the light. Conventionally, various pigments have been used for the white paint, but TiO ₂ and ZnO have been widely used from the viewpoint of hiding power, coloring power, heat resistance, chemical stability and the like.

[0003] However, paints using these pigments are:
When the painted product is used for the outer wall of a building due to insufficient light reflectivity, the internal temperature rises, so that a large amount of heat insulating material needs to be used. In addition, when it is used for a ceiling or wall in a room, there is a disadvantage that the light source of the indirect lighting must be brightened or the number of installation locations must be increased.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating composition and a coated product in which a coating film reflects visible light and near infrared rays at a higher rate than before.

[0005]

DISCLOSURE OF THE INVENTION The coating composition of the present invention comprises:
It is characterized by containing ZnAl ₂ O ₄ powder. The coated product is characterized in that the coating composition is applied to a substrate and dried.

[0006]

The present inventors have studied various types of chemically stable white pigments in which the coating film reflects visible light and near-infrared rays at a higher rate than before, and as a result, have found that ceramic sintered bodies having high heat resistance and high strength have conventionally been obtained. ZnA, which has been attracting attention as a raw material for concrete, has been used mainly for furnace materials and jigs used in high-temperature environments.
It has been found that using l ₂ O ₄ powder as a pigment gives good results. FIG. 1 shows ZnAl ₂ as a white pigment.
The spectral reflectance spectrum of a coated steel sheet containing 70% by weight of each powder of O ₄ , TiO ₂ or ZnO with respect to the non-volatile content of the paint, with respect to light having a wavelength of 0.2 to 2.5 μm, for each of the pigments. although, coating blended with ZnAl ₂ O ₄ powder is reflecting light wavelength 0.4~2.0μm 95% or more. On the other hand, TiO ₂ powder or Zn
The reflectance of the coating film containing the O powder in the visible light and near infrared regions is about 80%, which is about 15% lower.

[0007] ZnAl ₂ O ₄ is insoluble in acids and alkalis,
It is a chemically stable substance, and has a sufficient heat resistance of 1900 ° C. or higher. Further, since the hardness is higher than that of quartz, it is not crushed when dispersed in a varnish with a kneader. Therefore, the powder can be sufficiently used as a pigment. MgO powder is also a white substance having high reflectance, but cannot be used as a pigment because it reacts with water or carbon dioxide in the air or dissolves in an acid.

In order to use ZnAl ₂ O ₄ powder as a pigment, it is preferable to use a powder having a particle size in the range of 0.01 to 100 μm. If the particle size is less than 0.01 μm, light is transmitted or scattered, so the coating film does not reflect light,
The hiding power is also lost, and if it exceeds 100 μm, the surface of the coating film becomes uneven, so that the appearance is deteriorated.

It is preferable that the amount of the ZnAl ₂ O ₄ powder mixed into the paint is 30 to 90% by weight of the nonvolatile matter of the paint. 3
When the content is less than 0% by weight, the reflectance is not so different from the case where the conventional TiO ₂ powder or ZnO powder is used.
If the content is more than 10% by weight, the resin content of the binder becomes very small, so that the coating film processability deteriorates.

When the paint is a white paint, the pigment is ZnAl ₂
O ₄ powder alone may be used, or conventional TiO ₂ and / or ZnO may be used in combination. When the paint is white or light-colored, it is also possible to mix other inorganic or organic pigments. Further, in the case of a paint used for a part where a slight metallic texture is allowed, a metal flake can be added. Examples of the metal flake include flaky powders such as aluminum, stainless steel, nickel, tin, silver, copper, and bronze.

[0011] When producing the coating by using a ZnAl ₂ O ₄ powder, the ZnAl ₂ O ₄ powder is chemically stable as described above, air drying type, heat drying type, regardless of the heat melting type It can be used for organic solvent, water, and powder. There is no limitation on the type of resin, and any resin can be used. For example, in the case of organic resin, alkyd resin,
Acrylic, unsaturated polyester, epoxy, polyurethane, silicone, vinyl chloride, fluorine,
Resins of polyethersulfone, polyamide, polyimide, polyolefin, polyethylene terephthalate and the like may be used. It can also be used for paints containing an inorganic polymer as a main component.

[0012]

【Example】

Examples 1-4 A hot-dip galvanized steel sheet having a thickness of 0.5 mm (amount of coating:
250 g / m ² ) with an acidic nickel type surface conditioner [PL-40, manufactured by Nippon Parkerizing Co., Ltd.
15], a coating type chromate treatment solution [trade name: Jinchrome 1300AN, manufactured by Nippon Parkerizing Co., Ltd.] is applied and dried to obtain a chromium having a Cr adhesion amount of 40 mg / m ² . -A coating film is formed and an epoxy resin base coat is formed on the surface [Nippon Paint Co., Ltd.]
Product name, P-98 primer] in a dry film thickness of 5 μm.
m, and dried in an oven at a maximum temperature of 215 ° C. for 40 seconds.

Then, ZnAl ₂ O ₄ powder [average particle size of 2.5] was added on the undercoat film in an unsaturated polyester resin clear paint (trade name: H-25, manufactured by Nippon Paint Co., Ltd.).
μm, a purity of 99.9%, a reagent manufactured by Soegawa Rikagaku Co., Ltd.] so that the proportion of the non-volatile components in the paint becomes 30 to 90% by weight, and dispersed by a three-roll kneader. The prepared top coat was dried with a bar coater to a dry film thickness of 3
It was coated to a thickness of 0 μm and dried in an oven at a maximum temperature of 230 ° C. for 50 seconds.

Examples 5 to 9 In place of the top coat in Examples 1 to 4, ZnAl _{2 was used.}
20 to 30% by weight of O ₄ powder and TiO ₂ powder or ZnO
A top coat containing 30 to 40% by weight of the powder was applied.

[0015]

[Conventional example]

Conventional Examples 1 and 2 Instead of the top coat in Examples 1 to 4, a top coat containing 70% by weight of TiO ₂ powder or 70% by weight of ZnO powder was applied.

Next, the solar reflectance of the coated steel sheet obtained as described above was measured in accordance with the solar reflectance measurement method for a window glass film specified in JIS A 5759.
The results are shown in Table 1 together with the content of the pigment.

[0017]

[Table 1]

[0018]

As described above, as a white pigment, ZnA
The paint using l ₂ O ₄ powder is the same as conventional TiO ₂ powder or Z
Light reflectivity is higher than that using nO powder. For this reason, when using painted products as exterior materials for warehouses and cool storage, the temperature rise inside is small, so less heat insulating material is used, and when used for ceilings and walls in indirect lighting rooms. Eliminates the need to brighten the light source or increase the number of installation locations.

[Brief description of the drawings]

FIG. 1 shows a wavelength of 0.2 to 2.5 μm of a coated steel sheet coated with a powder-containing paint of ZnAl ₂ O ₄ , TiO ₂ or ZnO.
3 shows a spectral reflection spectrum for the light of FIG.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Enya 1 Nisshin Steel Co., Ltd. Technical Research Laboratory Painting and Composite Materials Research Dept. 7 at Takayashinmachi, Ichikawa, Chiba

Claims (2)

[Claims] 1. A light-reflective coating composition comprising ZnAl ₂ O ₄ powder. 2. A light-reflective coating product, wherein the coating composition according to claim 1 is applied to a substrate surface and dried.