JP2001113622A - Cold insulation panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold insulation panel suitable for use in a cold insulation chamber or a cold insulation vehicle. SOLUTION: A material wherein a film compounded with a moisture absorbent and a photocatalyst is formed on the surface of a base material is used. As the moisture absorbent, silica, alumina or zeolite is used and, as the photocatalyst, TiO2, WO3, ZnO, SrTiO3, BaTi4O9, RbPb2Nb3O10, ZrO2, Fe2O3 or SnO2 is used. As the moisture absorbent, one having fine pores is more preferable in order to effectively adsorbing moisture. As the photocatalyst, one having a small particle size and a large surface area is more preferable in consideration of the activating action to the moisture absorbent. The compound of the moisture absorbent and the photocatalyst is applied to the surface of the base material by roll coating, spray coating, dip coating, spin coating or electrodeposition coating and becomes a film having hygroscopicity. As the base material, a metal panel, glass, a tile or concrete used in a cold reserving housing or a cold reserving vehicle heterofore is used. The moisture absorbent and the photocatalyst are used in consideration of the kinds of them but generally used in a ratio of 1:(0.3-3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold storage and a cold storage, wherein the outer plate has a moisture absorbing effect and the temperature rise can be suppressed by utilizing the heat of vaporization taken off when the adsorbed moisture evaporates. The present invention relates to a cooling plate suitable for use in vehicles and the like.

[0002]

2. Description of the Related Art In a cool box or a cool car, a metal panel or the like in which a heat insulating material is interposed is used as a wall or a roof material in order to keep the inside at a low temperature. As the heat insulating material, foamed polystyrene, glass wool, or hard foamed urethane is often used, and as a member on the side that comes into contact with the outside air, a stainless steel plate, a painted steel plate, a concrete plate, or the like is used. The internal cooling is performed by a compressor of a compression type, an absorption type, a steam injection type, or the like. The surface temperature of the outer plate of a cool box or a cold pack rises due to irradiation of sunlight or the like, and the internal temperature rises due to the propagation of the heat. Therefore, an excessive amount of energy is required to keep the temperature low.

In order to suppress such energy loss, various measures have been studied to increase the thickness of the heat insulating material so as to reduce the influence of the temperature of the outside air. Further, a steel sheet coated with a paint containing a pigment that reflects visible light to far infrared light on the surface of the member may be used.

[0004]

Increasing the thickness of the heat insulating material has the effect of preventing the transmission of heat. However, since the heat insulating material becomes heavy, there is a natural limit to its use as a cold storage vehicle. Further, in the case of a material in which a coating film containing a heat-reflective pigment is formed, the effect of suppressing the temperature rise of the outer plate by reflecting light is hardly exhibited. The present invention has been devised in order to solve such a problem, and forms a composite coating film of a substance having a moisture absorbing action and a photocatalyst on an outer plate, and deprives the moisture adsorbed by the moisture absorbing agent during evaporation. It is an object of the present invention to provide a cold insulation plate having a self-cooling ability associated with the dissipated heat of vaporization and capable of suppressing a rise in temperature.

[0005]

Means for Solving the Problems In order to achieve the object, a cold insulating plate of the present invention has a composite structure having a basic structure that a film containing a moisture absorbent and a photocatalyst is formed on the surface of a substrate. It is a laminate. Here, by appropriately setting the type and the mixing ratio of the hygroscopic agent and the photocatalyst, the action of activating the hygroscopic agent of the photocatalyst becomes remarkable, and is repeated without requiring any external energy. The self-cooling ability accompanying moisture absorption can be exhibited. Further, by forming a metal thin film as an intermediate layer between the moisture-absorbing agent / photocatalyst-containing film and the substrate, a further cooling effect can be provided.

[0006]

When a photocatalyst is irradiated with light, electron-hole pairs are generated, the generated electrons reduce surface oxygen to generate superoxide ions (O ₂ ⁻ ), and the holes oxidize surface hydroxyl groups. Hydroxyl radicals (.OH) are generated, and organic substances are decomposed by an oxidation-reduction reaction of these highly reactive active oxygen species (O ₂ ^- and .OH). Although such a reaction occurs on the surface of the photocatalyst, the generated active oxygen has a certain lifetime, so that it is possible to decompose organic substances on the surface of the adjacent moisture absorbent. When an organic substance such as dirt or odor adheres to the surface of the moisture absorbent, the ability to absorb moisture is reduced. However, the organic substance is decomposed by light irradiation due to the adjacent photocatalyst. Therefore,
It is possible to prevent a decrease in the hygroscopicity, and the surface is always easy to adsorb moisture. The adsorbed moisture evaporates due to a rise in temperature, wind, or the like. At the time of the evaporation, heat is taken as heat of vaporization. Further, the titanium oxide represented by TiO ₂ and the hygroscopic agent represented by alumina used here also have excellent heat reflection characteristics. That is, since the reflectance from visible light to far-infrared light is high, there is also an effect of suppressing an increase in the temperature of the base material as thermal energy.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As a substrate, a stainless steel plate, a plated steel plate, an Al
Metal plates, such as glass and tiles, concrete, slate plates, resin plates, and the like. As the hygroscopic agent, inorganic silica, alumina, zeolite or the like is used. TiO ₂ , WO ₃ , ZnO, SrTiO ₃ , BaTi
₄ O ₉ , RbPb ₂ Nb ₃ O ₁₀ , ZrO ₂ , Fe ₂ O ₃ , SnO _{2 and the} like are used.
From the viewpoint of effectively adsorbing moisture, the hygroscopic agent is preferably one having fine pores. The photocatalyst also preferably has a smaller particle size and a larger surface area in consideration of the activating action on the moisture absorbent. In particular, alumina and TiO ₂ is excellent in reflection properties of visible light-far infrared, when the combination is the most cold excellent in configuration. The metal thin film provided as an intermediate layer between the moisture absorbent / photocatalyst-containing film and the substrate can be easily formed on the surface of the substrate by physical metal coating such as sputtering or vapor deposition. As the coating metal in this case,
It is preferable that the heat reflection characteristics such as Fe, Cr, Ni, Al and alloys thereof are excellent.

[0008] The blend of the hygroscopic agent and the photocatalyst is applied to the surface of the substrate in an appropriate form such as roll coating, spray coating, dip coating, spin coating, electrodeposition coating, etc., to form a film having hygroscopicity. As the base material, a metal plate, glass, tile, concrete, or the like, which has been conventionally used for a cool box or a cool car, is used. Although it depends on the types of the moisture absorbent and the photocatalyst, usually, the moisture absorbent is formed into a film having a ratio of 0.3 to 3 of the photocatalyst to one. Photocatalyst compounding ratio is 0.3
If it is less than the above, the effect of activating the hygroscopic agent becomes small. On the other hand, if the mixing ratio of the photocatalyst exceeds 3, the activation effect is large, but the ratio of the hygroscopic agent is relatively small, and the required hygroscopic property cannot be obtained. The larger the film thickness, the greater the amount of moisture absorption, the greater the heat of vaporization when the water is vaporized, and the better the cold insulation of the cold insulation plate. It is preferred that

A method for manufacturing a cold insulation plate will be described with reference to an example in which a film is formed using a stainless steel plate as a substrate and silica as a moisture absorbent and anatase TiO2 as a photocatalyst. After applying a silica sol consisting of colloidal silica containing an inorganic pigment and alkoxysilane to a pre-treated stainless steel plate,
Upon the heat treatment, a polymer layer made of a SiO ₂ precursor having a masking property is formed. On this primer layer, anatase TiO ₂
Then, when a silica sol containing an inorganic pigment is applied and heat-treated, a top layer exhibiting a photocatalytic action is formed. The silica sol is obtained by dissolving an organosilicate having the structure of R ¹ Si (OR ² ) 3 (where R ¹ and R ² represent alkyl groups) in an organic solvent and water, and adding colloidal silica. You. Although the alkyl group is not particularly limited, since the amount of organic components remaining after the heat treatment is reduced,
Those having a smaller number of carbon atoms are more preferable. Among them, a methyl group is preferred.

The heat treatment temperature for forming the primer layer is 60 to 3
It is selected in the range of 50 ° C. If the heat treatment temperature does not reach 60 ° C., drying becomes insufficient, and unevenness occurs when the top layer is formed. Conversely, when the heat treatment temperature for forming the polymer layer is 3
When the temperature exceeds 50 ° C., cracks occur, and the coating film is easily peeled off from the substrate surface. The heat treatment temperature for forming the top is 15
It is selected in the range of 0 to 400 ° C. Heat treatment temperature is 150
When the temperature does not reach ℃, the condensation polymerization of the silica-based coating film becomes insufficient and poor adhesion is likely to occur. Conversely, when the heat treatment temperature is higher than 400 ° C., cracks tend to be easily generated.

The heat treatment temperature at the time of forming the top is preferably set higher than the heat treatment temperature at the time of forming the primer layer. More preferably, the temperature at the time of forming the primer layer is set to 80 to 140 ° C. and the heat treatment temperature at the time of forming the top layer is set to 160 to 250 ° C. in order to exclusively dry the coating film. By this temperature setting, a large amount of alkyl groups remain after the formation of the polymer layer, so that a strong bond with the top layer is obtained, and the adhesion between the polymer layer and the top layer is improved by heat treatment at the time of forming the top layer. Therefore, a coating film having good adhesion to the substrate and no cracks is formed.

As a light source necessary for photoexcitation of the photocatalyst, which is necessary for efficiently absorbing and desorbing the desiccant and suppressing a rise in surface temperature, not only sunlight but also indoors Light sources such as lighting, fluorescent lamps, incandescent lamps, metal halide lamps, mercury lamps and xenon lamps can also be used.

[Example 1] An anatase type TiO ₂ powder having an average particle size of 7 nm was used as a photocatalyst, and a silica-based inorganic material in which colloidal silica and methyltrimethoxysilane were contained in a mixed solvent comprising butyl cellosolve, isopropanol, and water SUS304 with paint (solid silica 20%) as binder
A stainless steel plate (plate thickness: 0.5 mm) was painted with a spray. The firing conditions were 240 ° C. for 20 minutes. TiO ₂ concentration in coating film is 40%
The coating thickness was 20 μm.

[Example 2] In Example 1, SUS304 stainless steel sheet (thickness:
0.5 mm) with a splay and fired at 360 ° C. for 2 minutes. The TiO ₂ concentration in the coating was 30%, and the coating thickness was 10 μm.

[Comparative Example 1] Uncoated SUS304
(Plate thickness: 0.5 mm) was prepared.

Comparative Example 2 A SUS304 stainless steel plate was coated with a silica-based inorganic paint (solid silica 20%) containing colloidal silica and methyltrimethoxysilane in a mixed solvent of butyl cellosol, isopropanol, and water. . The firing conditions were 240 ° C. for 20 minutes. The thickness of the formed silica layer was 20 μm.

A mini-house was manufactured using the above-mentioned various materials, and the internal temperature in a state where sunlight was irradiated was measured. Table 1 shows the results. In this measurement, the difference in the internal temperature depending on the type of the outer plate is examined, and the energy loss during cooling is not particularly measured.

[0018]

[Table 1]

From Table 1, it can be seen that the internal temperature is considerably high when the stainless steel plate is solid, and the effect of suppressing the temperature rise is hardly recognized by simply applying the silica coating. On the other hand, when the mini-house was manufactured using the stainless steel sheet having the coating film of TiO ₂ + SiO ₂ or TiO ₂ + Al ₂ O ₃ obtained in the example, the internal temperature decreased by 5 ° C. or more.

[0020]

As described above, in a cold box or a cold pack, the surface temperature rises due to the irradiation of sunlight or the like, and excessive energy is required to keep the internal temperature low. A cool box using the cool plate of the present invention, a cool car,
Since the outer plate has a moisture absorbing effect, the temperature rise can be suppressed by the heat of vaporization taken off when the adsorbed moisture evaporates. In addition, since the photocatalyst layer has an effect of preventing dirt, the appearance of the cool box or the cool car can be kept clean for a long time. Furthermore, since it also has the effect of purifying the air, it also contributes to lowering the concentration of harmful gases.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshige Nakamura 7-1, Takatani Shinmachi, Ichikawa City, Chiba Prefecture Nisshin Steel R & D Co., Ltd. (72) Inventor Kenji Sakado 7 F-term (Reference) 3R044 AA04 BA01 CA11 DD01 3L102 LB02 MB16 MB19 4F100 AA19B AA19H AA20B AA20G AA20H AA21B AA21H AA25B AA25H AA33B AA33H AB01 A00A00A00A00A04A00A00A00A00A00A00A00A01A00A00A01A01A00A00A04A01A00A04A00A01A01A01A00A01A00A01A00A04A01A00A01A01A00A01A01A01A01A00A01A01A01A01A01A01A01A01A01A00 BA07 BA10A BA10B CA30B CC10 GB07 GB51 JB20B JD15 JD15B JJ02 JJ05 JM02C

Claims (5)

[Claims] 1. A composite laminate in which a film of a composite composition comprising a hygroscopic agent and a photocatalyst is formed on the surface of a substrate, wherein the composite film has a self-cooling ability accompanying moisture absorption and desorption of the surface film. Cold plate. 2. The cold insulation plate according to claim 1, wherein the moisture absorbent is one or more kinds selected from silica, alumina, and zeolite. 3. The photocatalyst is composed of TiO ₂ , WO ₃ , ZnO, SrTiO ₃ , BaTi
_{4 O 9, RbPb 2 Nb 3} O 10, ZrO 2, Fe 2 O 3, 1 kind selected from SnO ₂ or more at which claim 1 cold plate according. 4. The base material of the outer plate is a metal plate, glass, tile,
The cold insulation plate according to claim 1, wherein the plate is a simple substance or a composite of any of concrete and resin. 5. The method according to claim 1, wherein the moisture absorbing agent / photocatalyst-containing film and the substrate are
5. The cold insulation plate according to claim 1, wherein a metal thin film is formed as an intermediate layer.