JP2006095709A - Coated steel panel excellent in conductivity/heat absorbing and releasing properties - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a coated steel panel constituted so as to efficiently absorbing heat from an exothermic part and suitable for suppressing rise in the temperature of the exothermic part. <P>SOLUTION: A clear coating film by resin coating having an aromatic ring and containing 1-50 wt.% of a conductive filler is provided in a dry film thickness of 2-15 μm. A base material may be a plated steel panel or a stainless steel panel provided with a black coating type chemical conversion treated film. Further, the plated steel panel or the stainless steel panel is used as the base material and the clear coating film by resin coating having the aromatic ring and containing 1-50 wt.% of the conductive filler and an organic pigment having the aromatic ring may be provided on the base material in the dry film thickness of 2-15 μm. Either one of a heat absorbing and releasing and/or conductive coating film or a known coating film constitution of the coated steel panel may be provided on the opposite surface of the base material in the same way. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive coated steel sheet having improved absorption and heat dissipation.

  IT-related parts and semiconductor parts such as CPUs, power transistors, and disk drives generate heat during operation and rise in temperature. High temperatures are not only dangerous for the user, but also cause malfunctions and malfunctions of the heat generating devices, parts and devices. Troubles due to temperature rise become more serious as the size and density of heat generating devices and parts become smaller. In order to prevent malfunctions and malfunctions due to temperature rise, there is a method of cooling with a fan or the like by blowing cold air to the heat generating equipment or parts. However, the number of parts such as fans increases and the size and weight of the final product also increase. . There is also a method of covering the heat generating device and parts with a casing having a drafting action, but it is necessary to form a ventilation hole in the casing for the drafting action, resulting in a casing having poor airtightness and electromagnetic shielding properties.

In response to the demands for miniaturization and higher density, it is necessary to improve the heat dissipation characteristics of the material itself that constitutes the casing in order to obtain a casing excellent in confidential electromagnetic shielding properties. The excellent heat dissipation characteristics of the material itself are not only used for housings for electric appliances and electronic equipment, but also when used for reflectors for lighting fixtures and parts such as fluorescent lamps and liquid crystal backlights. It is a characteristic required for various applications such as an increase in Also, in IT-related parts and semiconductor parts such as CPUs, power transistors, and disk drives, as the operating frequency or output increases, the housing is required to have higher electromagnetic shielding properties. At the time of forming, a high electromagnetic seal property, that is, high conductivity is required particularly for the coating film on the inner surface side of the housing.
JP 2004-224017 A

  The present invention has been devised in order to meet such demands, and it is possible to efficiently generate heat by providing a heat-absorbing coating film having heat-absorbing and radiating properties and conductivity based on a plated steel plate or a stainless steel plate. The object is to provide a coated steel sheet that absorbs and dissipates to the outside and also has high electromagnetic shielding properties.

  In order to achieve the object, the coated steel sheet of the present invention is characterized in that a clear coating film with a resin coating having an aromatic ring containing 1 to 50% by weight of a conductive filler is provided in a dry film thickness of 2 to 15 μm. To do. The base material may be a plated steel plate or a stainless steel plate provided with a black coating-type chemical conversion coating. Furthermore, a clear coating film having an aromatic ring containing a plated steel plate or a stainless steel plate as a base material and containing an conductive filler in an amount of 1 to 50% by weight and an organic pigment having an aromatic ring in a dry film thickness of 2 to 2 You may provide 15 micrometers. Similarly, the opposite surface may be provided with either a heat absorbing / dissipating and / or conductive coating film or a coating film structure of a known coated steel sheet.

  With the coated steel sheet of the present invention, heat from the heating device and parts is efficiently absorbed by the coating film, and is conducted to the outside by conducting heat through the metal substrate. Therefore, the lifetime reduction in the member due to the temperature rise is prevented, and a reliable structural member is obtained. Moreover, since it is a clear coating film, it becomes a product with high design property in which the base metal luster is utilized and a light color tone is imparted.

  The coated steel sheet of the present invention uses a plated steel sheet or a stainless steel sheet as a metal base material 1 and is provided with a heat-absorbing and heat-dissipating conductive coating film 2 on one surface of the metal base material 1 and an overcoating film 4 on the other surface through an undercoat film 3. ing. (Fig. 1) Prior to the formation of coating films 2 and 3, degreasing, pickling, surface conditioning treatment, chromate treatment, black chromate treatment, phosphate treatment, black phosphate treatment, chromium-free treatment, black chromium-free treatment, etc. If necessary, one or two or more kinds of pre-coating treatments may be applied, and the chemical conversion treatment film 5 effective for improving the adhesion of the coating film may be provided on the surface of the metal substrate 1.

  The chemical conversion treatment may be appropriately selected depending on the combination with the metal base material and the paint, but if a black coating type chemical conversion treatment is performed, higher heat absorption and heat dissipation can be obtained. Black coating-type chemical conversion coatings are known coating-type chromate coatings, known silica-based, zirconia-based, titanium-based coating-type chromium-free coatings, carbon black, carbon graphite, etc., or cyanine black, iron oxide black, etc. It can be formed by adding a black pigment. In particular, carbon black and carbon graphite are suitable for the present invention because they have a small particle size and also have conductivity when added to the chemical conversion coating. An effect can be expected if the black color here is 50 or less as the lightness L value of the painted plate after clear coating.

  The metal substrate 1 is made of zinc, such as hot-dip zinc, alloyed hot-dip zinc, electric zinc plating, zinc-aluminum alloy plating such as zinc-5% aluminum, zinc-55% aluminum, zinc-aluminum-magnesium, zinc- A plated steel plate provided with a plating layer 6 such as nickel or aluminum-silicon, or a solid stainless steel plate is used. In order to improve the heat absorption efficiency by promoting irregular reflection on the substrate surface, a substrate having a large surface roughness is highly effective.

  The resin used in the present invention has an aromatic ring. As a result of experiments, it was found that a resin having an aromatic ring has higher heat absorbability than other resins. Although it is thought that the conjugated double bond of the aromatic ring increases heat absorption by the interaction with the nearby unpaired electrons and other double bonds contained in the resin, the principle is not clear. . Examples of such resins include polyester resins such as regular polyester resins and polymer polyester resins, epoxy resins, and epoxy-modified polymer polyester resins. A known curing agent such as urethane or melamine resin can be used in accordance with the resin. By being a clear coating film, heat absorption by the aromatic ring can be efficiently performed without being blocked by the pigment. Moreover, generation | occurrence | production of a pressure mark can be suppressed by using a clear coating film for a back surface coating film.

  A conductive filler is added to the clear coating film to impart conductivity. Examples of the conductive filler include metal powders such as nickel, silver, tin, copper, aluminum, and iron, and phosphorous iron. Although there are no restrictions on the particle size and the like, nickel powder, phosphorous iron powder and the like are desirable from the viewpoint of conductivity and stability in the paint. Phosphorus iron is also preferable from the viewpoint of improving heat absorption and dissipation. The addition amount is desirably 1 to 50% by weight in the coating film. If it is less than 1%, the conductive effect is not sufficient, and if it exceeds 50%, the paintability deteriorates.

  Moreover, when the coating film needs to be colored depending on the intended use, an organic pigment having an aromatic ring can be used as the coloring pigment. Other pigments block the absorption effect of the aromatic ring, but organic pigments having an aromatic ring do not. Examples of such pigments include cyanine blue, cyanine green, and cyanine red.

  The coating film has a dry film thickness of preferably 2 to 15 μm. If it is less than 2 μm, the film thickness is too thin and the heat absorption effect is not sufficient, and if it exceeds 15 μm, cracks and the like are likely to occur during baking. The heat-absorbing and heat-dissipating conductive coating film may be disposed on both sides or on one side. In the case of one side, a commonly used PCM coating and pretreatment can be used on the opposite side.

  Heat absorption can be expressed by emissivity. The emissivity measures the temperature rise of the sample when a certain amount of heat is irradiated to the sample, and can be measured with a D & S AERD emissivity meter (manufactured by Kyoto Electronics Co., Ltd.).

  Surface adjustment treatment is applied to a 0.5 mm thick hot-dip galvanized steel sheet, and after coating chromate treatment, the polyester primer on the front side is 5 μm in dry film thickness, and the polyester overcoat is 13 μm in dry film thickness on the back surface. A coating film having the composition shown in Table 1 (Nos. 1 to 16) was painted and baked, and the emissivity and conductivity of the back surface were measured in a constant temperature room at 20 ° C. The emissivity was measured with an ESP probe using a D & S AERD emissometer (manufactured by Kyoto Electronics Co., Ltd.) and the conductivity using a Loresta GP (manufactured by Mitsubishi Chemical Corporation).

Instead of the coating type chromate treatment in Example 1, a black coating type chromate treatment in which carbon black was added to the coating type chromate treatment (NRC300 manufactured by Nippon Paint Co., Ltd.) to 1% in terms of solid content was applied to a chromium coating amount of 30 mg / m. ^It was applied and dried so as to be ^2, and a paint having the composition shown in Table 1 (Nos. 17 to 20) was applied and baked on the back side, and the emissivity and conductivity of the back side were measured.
[Comparative Example 1]

In Example 1, the back surface coating film was replaced with Nos. 21 to 25 in Table 1, and the emissivity and conductivity of the back surface were measured in the same manner.

  As shown in Table 1, the emissivity and electrical conductivity were good in the present invention, but No. 24 with a small amount of conductive powder is a resin that lacks conductivity and has a small film thickness. No. 21 and 22 No. 25 to which a pigment having no aromatic ring was added lacked the emissivity. Moreover, in order to confirm the heat dissipation effect, three test pieces of 120 × 60 mm were cut out from the No. 2 coated steel plate and subjected to a heat dissipation test. In the heat dissipation test, the heater 12 is accommodated in the test box 11 of FIG. 2 with the upper and side surfaces open, the distance from the heater 12 to the test piece 10 is fixed to 50 mm, and the test piece 10 is placed on the upper and side surfaces 2 of the box. The surface was fixed in close contact with the heater on the back side. When the temperature in the box after 2 hours when the temperature in the test box was stabilized was measured by applying a heat amount of 10 W to the heater 12, the coated steel plate No. 1 (emissivity 0.70 with the heat absorbing and radiating coating film) was measured. ), The temperature after 2 hours was 50 ° C., but when using a solid galvanized steel sheet (emissivity 0.08) with no heat-radiating coating film on the back side, the temperature after 2 hours was The temperature rose to 80 ° C., and the heat dissipation effect by the heat absorbing / dissipating coating film was confirmed.

  As described above, according to the present invention, a coated steel sheet having excellent absorption and heat dissipation can be obtained.

Sectional view of a coated steel sheet according to the present invention Test equipment investigating the effect of heat absorption and heat dissipation characteristics of coated steel sheet on temperature rise inside the housing

Explanation of symbols

1: Metal substrate 2: Heat-absorbing and heat-dissipating conductive coating 3: Undercoat coating 4: Top coating 5: Chemical conversion coating 6: Plating layer

Claims (3)

  A conductive film characterized in that a clear coating film with a resin coating having an aromatic ring containing 1 to 50% by weight of a conductive filler based on a plated steel plate or stainless steel plate is provided in a dry film thickness of 2 to 15 μm. Painted steel sheet with excellent heat absorption and dissipation. 2. The coated steel sheet having excellent conductivity and heat absorption / radiation properties according to claim 1, wherein the base material is a plated steel sheet or a stainless steel sheet provided with a black coating-type chemical conversion coating. A resin coating having an aromatic ring containing 1 to 50% by weight of a conductive filler based on a plated steel plate or a stainless steel plate and a clear coating with an organic pigment having an aromatic ring is provided in a dry film thickness of 2 to 15 μm. A coated steel sheet with excellent conductivity and heat absorption and heat dissipation.

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