JP3137938B2 - Portable electronic devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment of a part which may be touched by a person, and a special purpose mainly for a treatment for a body temperature of a portable electronic device housing made of metal. It is about painting. In this specification, a case is described as a surface-treated member (hereinafter, referred to as a surface-treated member), particularly focusing on a metal housing of an electronic device. However, the surface-treated member of the present invention can be touched by a human. It can be widely applied to the surface tactile sensation temperature countermeasure treatment application in general members such as a stove case having a property, a metal guard of a cooking utensil, and a wall or a floor member of a building. In addition, the object to be treated is not limited to metal, but is effective as long as it is a material having a high thermal conductivity.

[0002]

2. Description of the Related Art As a conventional technique, an example of countermeasures in electronic equipment will be described. For example, in recent years, in portable devices such as portable personal computers, mobile phones, portable video cameras, and electronic organizers, semiconductor devices have not only been cooled, but also have become smaller (thinner), and as the packaging density has increased, the housing surface has been heated and heated at a higher temperature. Countermeasures are also an important issue. On the other hand, in the past, the housing of a portable device was often made of a resin housing such as ABS (acrylonitrile-butadiene-styrene copolymer). Are increasingly used. However, in the case of a metal housing, the surface is 50 ° C.
Above this, there is a problem that the casing is hot and cannot be held, and if it is touched for a long time, it may lead to low-temperature burns. Challenges have arisen. The reason for this is that when a low thermal conductive material such as the conventional ABS (thermal conductivity λ = about 0.1 W / mK) is touched with a finger, the amount of heat supplied to the portion deprived by the finger contact is small. On the other hand, high heat conductive materials such as aluminum (thermal conductivity λ = about 220 W / mK), on the other hand, are continuously supplied with heat from a heat source, so that a large amount of heat flows into the hand, resulting in discomfort. Because it leads to. As a conventional countermeasure against such a tactile temperature, there is the following example.

For example, a conventional countermeasure example 1 as shown in FIG.
Then, by attaching a cloth such as a felt 4 having a low thermal conductivity to the metal casing 1 heated to a high temperature by the heating element such as the heating element 3, it is possible to reduce a direct heat flow to the hand. . As a product application example, see JP-A-6-29665.
In general, there are cases of treatment in a sauna room and measures against a high-temperature portion around a printer thermal head as disclosed in JP-A-5. A similar measure can be taken by attaching a heat insulating material other than a cloth. In Japanese Patent Application Laid-Open No. Hei 6-26659, a rubber-like heat insulating material is provided on the grill door handle.
In Japanese Patent Application Publication No. 2 (1995) -207, a rubber-like protective sheet is attached to an electric heating table to take measures.

Further, as disclosed in Japanese Patent Application Laid-Open No. H8-74450, there is a case where a mesh material is attached to a door handle for construction to take measures against the tactile temperature when the door is opened and closed in a cold or extremely hot place.

[0005] In addition, as shown in a conventional countermeasure example 2 shown in FIG.
It is also common to apply a bonding process.
Japanese Patent Application Laid-Open No. 6-7599 discloses an iron or kotatsu heater around a heater.

It is also common to apply a paint 6 to the metal housing 1, which is to be a high temperature surface, as in Conventional Countermeasure Example 3 shown in FIG.

Further, as a conventional countermeasure example 4, there is disclosed a high-temperature countermeasure technology in which a coating material contains heat-expandable microcapsules and the heat-expandable microcapsules are heated and foamed. For example, Japanese Patent Application Laid-Open No. Hei 6-99133 discloses that a thermally expandable microcapsule whose shell wall is softened at a temperature lower than the curing temperature of a thermosetting resin is applied to paint (solid content 70%).
A step of applying wood grain using a thermosetting paint containing 5 to 30% by weight, and a step of baking and drying the microcapsules in the baking step. There is disclosed a method for forming a coating film having a woody feel, wherein the coating film is cured. Japanese Patent Application Laid-Open No. 62-39674 discloses that a thermoplastic resin vehicle is used, and a heat-expandable microcapsule is added to a coating composition comprising a pigment, a filler, a solvent, etc., in an amount of 100% by weight. After applying and drying the heat-insulating pattern paint composition prepared by mixing 10 to 80 parts by weight per part on any wall, ceiling, floor, or the like, the heating film is brought into contact with the surface to expand the dried coating film. There is disclosed a method for forming a heat-insulating patterned coating film characterized by the following. In addition, Japanese Patent Application Laid-Open No. Hei 2-303573
In the official gazette, the heat-expandable microcapsules are dispersed in a curable coating at a temperature lower than the foaming temperature of the microcapsules, applied to the entire surface or a part of the substrate, and cured.
Thereafter, a method for forming a coating film having an uneven pattern, characterized by further applying a top coat and heating to a temperature higher than the foaming temperature of the microcapsules, is disclosed. In recent years, particularly in portable electronic devices represented by mobile computers, mounting technology for realizing small size, high performance, and light weight has become a key point of product differentiation. From such a background, metal die-cast housings having excellent strength against weight are increasing. The metal housing has a thermal conductivity that is two to three orders of magnitude higher than that of a conventional resin housing, which is advantageous in terms of a heat dissipation structure. On the other hand, there is a problem that when a person touches the surface, the surface feels hotter than a resin housing at the same temperature due to a heat collecting effect. Especially in recent mobile computers, CPU (Central Processi
It is a problem to raise the temperature of the housing surface due to an increase in local heat generation in the (ng Unit) part, and measures must be taken. As previously mentioned,
Pile flocking is generally used as a means to alleviate the feel temperature of the metal surface, and there are examples of countermeasures in kotatsu and thermal heads of printers. However, pile flocking has a problem in design and the like when applied to an electronic device housing. There are also countermeasures such as attaching a resin-based sheet, but there are many problems in shape followability, productivity and design.

[0008]

SUMMARY OF THE INVENTION
2 is effective on the perceived temperature, but when applying a measure such as rubber or mesh to a case-shaped surface having a complicated free-form surface such as an electronic device, it is adapted to the shape. There are difficult tasks. In addition, in the flocking method, it is difficult to uniformly adhere the fibers to the intricately shaped portion, and there is a problem that the degree of freedom of the allowable housing size and shape is small. Further, even if the treatment is successfully completed, there is a problem that the design does not withstand product specifications because problems such as dirt and wear remain. Further, there is a problem in terms of productivity and the like, and there is also a problem that the cost is increased.

In comparison with the above, the coating which is a general exterior method in a metal casing as shown in Conventional Countermeasure Example 3 in FIG.
Excellent in design, productivity and cost and reasonable. However, in the normal coating, since the coating thickness is usually only about 40μm, almost no effect on the tactile temperature can be expected,
The tactile sensation of the metal base cannot be softened, and the effect of countermeasures against the tactile temperature cannot be expected.

In addition, as shown in Conventional Measure Example 4, there is a technique of forming a woody feeling, a concave-convex pattern, or a heat-insulating pattern by using a heat-expandable microcapsule contained in a paint. However, none of these technologies was aimed at reducing the tactile temperature, and was not a technology for softening the metal-based tactile temperature.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and by devising a surface treatment method based on a coating, the design of the conventional coating, the followability to various shapes / processing productivity. It is another object of the present invention to realize a tactile temperature countermeasure process while maintaining advantages such as low cost. In particular, an object of the present invention is to provide a paint that does not damage the surface while softening the tactile temperature on the surface of the housing of a portable electronic device made of metal, improving the product specifications in terms of design. "Insulating" and "reducing the tactile temperature" in the invention are different concepts. "Insulating" means to shut off heat and not to conduct heat. For example, "insulating" the surface of the housing of a portable electronic device means that heat generated inside the portable electronic device is confined inside,
It may cause a failure. On the other hand, "reducing the tactile temperature" means that when heat generated inside the portable electronic device is radiated from the housing surface to the outside, the heat radiation reduces the amount of heat flowing into hands and fat. . In other words, "reducing the tactile temperature" means that heat dissipation from the surface of the housing of the portable electronic device must be promoted and that discomfort to the human body due to the heat dissipation must be eliminated. This is a technique for satisfying two conflicting requirements. As described above, the present invention provides a coating technique for reducing the influence on the human body due to heat dissipation while maintaining heat dissipation.

[0012]

A surface-treated member according to the present invention includes a metal member having a surface, and a coating film formed on the surface of the member and having a layer for reducing a tactile temperature. A foam layer formed by applying a coating material containing less than 5% by weight of a foam material and foaming the applied material.

[0013] The coating material contains about 1% by weight of a foaming material.

[0014] The coating film is characterized in that a top coating layer having higher hardness than the foamed layer is provided on the foamed layer.

The top coating layer is formed of a bead-based coating material containing beads.

The coating material is one of a paint, a resin coating material, and a primer.

The metal member is made of any one of aluminum, magnesium, an aluminum alloy, and a magnesium alloy.

The thickness of the foam layer is not more than 100 μm.

The thickness of the foam layer is 45 to 80 μm.

The thickness of the top coating layer is 10
It is not more than 0 μm.

The thickness of the top coating layer is 45
６０60 μm.

[0022] The layer for reducing the tactile temperature contains a heat insulating filler.

[0023] The layer for reducing the tactile temperature includes a granular heat insulating material.

[0024] The coating film is characterized in that it has irregularities on the surface.

The surface treatment method according to the present invention is a surface treatment method for lowering the tactile temperature by coating a metal surface, wherein a coating material containing less than 5% by weight of a foaming material is applied, and the coating material is heated. Drying and foaming the foamed material to form a foamed layer.

[0026] The above surface treatment method is characterized by further comprising a step of forming a top coating layer having a higher hardness than the foamed layer on the foamed layer.

The step of forming the top coating layer includes a step of applying a bead-based coating material containing beads.

[0028] The step of applying the coating material containing the foaming material is characterized in that it comprises a step of mixing 1% by weight of the foaming material into the coating material.

In the step of forming the foamed layer, the foamed layer is
The method is characterized by having a step of forming a thickness of 5 to 80 μm.

The step of forming the top coating layer includes a step of making the top coating layer have a thickness of 45 to 60 μm.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In view of the design, mass productivity, and cost reduction required for electronic equipment housings, countermeasures by improving paints are promising. In the following, a trial painting method was examined for a countermeasure coating method using the following concept as a countermeasure.

1. It is known that, when semi-infinite solids of different temperatures come into contact with each other, the contact portion intermediate temperature Tm can be roughly estimated by equation (1). In other words, if you consider your hand as a semi-infinite solid, β
Tm value is less affected by the temperature of the counterpart object as it comes into contact with a material smaller than ₂ . Applying this principle, we examined "improvement of physical properties of paint film (improvement of heat insulation property)" as a first trial production guideline. "Improvement of thermal insulation" here means
It does not mean "insulate". This “improvement of heat insulation” means that the amount of heat transfer from the paint film to the hand is reduced. Tm = (β ₁ T ₁ + β ₂ T ₂ ) / (β ₁ + β ₂ ) (1) β ₁ = λ ₁ / √α ₁ β ₂ = λ ₂ / √α ₂ (2) where α _{1 is a} human body thermal diffusivity _{^{(m 2 / S) β 1}} : human thermal effusivity (W (√S) / (m 2 K)) α 2: thermal diffusivity of the touch object _{^{(m 2 / S) β 2}} : contact Thermal permeability of the object (W (√S) / (m ²
K)) λ ₁ : Thermal conductivity of human body (W / (mK)) λ ₂ : Thermal conductivity of contact object (W / (mK)) T ₁ : Temperature of human body (K) T ₂ : Temperature of contact object (K)

2. Acceleration of thickening of the coating film The heat transmission rate in the coating film is calculated by the following equation (3), and by increasing the film thickness in addition to the above-mentioned improvement of the physical properties, heat transmission of the hand can be suppressed. From this, "thickening of the coating film" was examined as a second trial production guideline. U = λ / d (3) U: heat transmittance of coating film (W / m ² K) d: thickness of coating film (m)

3. As a third guideline, a method for reducing the true contact area with the finger by making the surface uneven was studied as a third measure. That is, it can be expected that the contact thermal resistance on the film surface increases and the amount of heat transfer to the hand decreases.

Various coating examples based on the above-mentioned measures 1 to 3 will be described below.

Embodiment 1 FIG. 1 shows an embodiment of a surface-treated member that has been subjected to the sensible temperature treatment method according to the present invention. The elliptical frame portion in FIG. 1 is a housing surface portion heated by the heating element 3 mounted immediately below and heated to a high temperature. FIG. 2 is a housing mounting cross-sectional view showing a cross-sectional portion taken along the line AA in the perspective view of FIG. As the metal housing 1, for example, magnesium or a magnesium alloy is used. Alternatively, aluminum or an aluminum alloy may be used. Or, the other density is 4.0 g / cm ³ or less or 5.
A light metal of 0 g / cm ³ or less may be used. In general coating, since it is difficult to apply thick film coating, a base is formed in advance with the resin coating material 7 to increase the thickness of the surface treatment layer, thereby improving the tactile temperature characteristics. As a concrete base material, vinyl chloride resin, for example, Japan Special Paint Co., Ltd.
And the product name "NT Guard Coat" or the like may be used. In this example, different types of coating materials (paint 6 and resin coating material 7) are arranged in a multilayer structure, the thickness of the surface treatment layer is increased, and the tactile temperature characteristics are improved. Also, instead of vinyl chloride resin, polymer compounds (polymers)
For example, acrylic resin, fluorine resin, vinyl resin, phenol resin, polyester, epoxy resin, polyethylene, rubber, urea resin, melamine resin, urethane resin, silicon resin, polyamide, etc.
This polymer may be used alone or in combination of two or more.

Embodiment 2 FIG. 3 is a cross-sectional view of a case in which a heat-insulating layer structure is formed by applying a paint in which a fibrous heat-insulating filler 8 is mixed into the paint 6. Due to the effect of lowering thermal conductivity,
Tactile temperature can be reduced. Specifically, as the heat insulating material filler 8, mica or pearlite having a low heat conductivity and a large heat insulating effect is used. In addition to mica and pearlite, diatomaceous earth (SiO ₂ + H ₂ O), alumina (Al ₂ O ₃ .nH ₂ O) powder, inorganic particles such as calcium carbonate (CaCO ₃ ), titania (TiO ₂ ) or cow skin, Pulverized material such as synthetic leather may be used. The heat insulating filler 8 also has the effect of increasing the coating film thickness because it also functions as a filler. The heat insulating material filler 8 may be mixed with the resin coating material 7.

Embodiment 3 FIG. 4 is a cross-sectional view of a case in which a paint in which a large number of granular heat insulating materials 9 are mixed in the paint is applied. Specific materials include cork powder that has a low thermal conductivity and a large heat insulating effect, and air bead materials that have hollow spheres (eg, OHASHI CHEMICAL INDUSTRIES LTD
Color polymer bead material product name “Rabi 1 type” enamel) is suitable, and the effect of lowering the effective thermal conductivity in the coating film can effectively reduce the tactile temperature. In addition, it also has the effect of increasing the coating film thickness because it also acts as a filler. It is preferable to use a bead diameter of 10 to 200 μm, but the larger the diameter, the better. Granular heat insulating material 9 may be mixed with resin coating material 7. Instead of the air bead material, carbon balloon, acryl and styrene balls, silicon salt mineral, silica alumina fiber, glass, etc. may be used, and the air bead material, carbon balloon, etc. may be used alone or in combination of two or more.

Embodiment 4 FIG. 5 is a conceptual cross-sectional view of a housing having a surface treatment structure in which air voids are created by previously mixing a foaming material 10 in a paint and foaming at a high temperature.
As a specific example of the foam material 10, a heat-expandable microcapsule such as a low-boiling hydrocarbon may be mixed as a foam material in a paint. For example, it is preferable to use a product name “Matsumoto Microsphere F50” manufactured by Matsumoto Yushi-Seiyaku Co., Ltd. By heating and foaming the coating material, a porous structure can be created in the coating film, and the effective thermal conductivity in the coating film can be reduced to reduce the tactile temperature. In addition, since it also has a function as a filler, it has the effect of increasing the coating film thickness.
The foam material 10 may be mixed with the resin coating material 7. Also. Foam glass, foam concrete, foam urethane, foam styrene, foam polypropylene, foam PET (polyethylene terephthalate) as foam material 10
May be used alone or in combination of two or more. Also, instead of the foam material 10, alumina (Al ₂ O _3.
nH ₂ O) powder, calcium carbonate (CaCO ₃ ), titania (Ti
O ₂ ), a material such as a silicon salt mineral, a glass ball, a styrene ball, and an acrylic ball may be contained in the paint 6 or the resin coating material 7, and the paint 6 or the resin coating material 7 may be stretched or applied. . At that time, the material becomes a spacer,
Voids are created on both sides of the material. Also, for example, the foam material 10
Alternatively, a monomer having a vapor pressure different from that of the paint 6 or the resin coating material 7 may be used alone or in combination of two or more. At the time of application, the monomer mixed as the foaming material 10 volatilizes to form a polymer having voids. An example of the relationship between the tactile temperature Ts that governs the thermal sensation of a person when touching a certain high-temperature metal surface and the thickness of the foam coating film is as shown in FIG. 6, and a thickness of about 50 μm or more can be taken. In this case, the tactile temperature is remarkably lowered, and when the temperature is about 300 μm or more or 500 μm or more, almost the same thermal sensation is obtained regardless of the thickness of the coating film. Therefore, in practice, 50 to 500 μm
If the processing is performed with a thickness up to the order, the efficiency is the highest.

In the following, the degree of the effect of the present embodiment is roughly evaluated using the heat transmission rate U as an index. As described above, “reducing the touch temperature” in the present invention means reducing the heat flow that flows into the hand or finger contacted by the heat generated inside the portable electronic device. Here, FIG. 23 schematically illustrates a heat flow state when a person touches the metal housing. In FIG. 23, λ _p : thermal conductivity of coating film (W / (mK)) λ _Al : thermal conductivity of aluminum (W / (mK)) λ _a : thermal conductivity of air (W / (mK)) α _p : thermal diffusivity of coating film (m ² / S) α _Al : thermal diffusivity of aluminum (m ² / S) α _a : thermal diffusivity of air (m ² / S) T _p : coating film (surface temperature (K) T _Al of the treated layer): aluminum body temperature (K) T _a: the air temperature (K) d _p: thickness of the coating film d _Al: aluminum casing thickness q _s: is a heat flow . In a metal housing made of aluminum or the like, heat is replenished from the surroundings in a wide horizontal plane to the area where the temperature has dropped due to touch, but the order of the thermal conductivity of the paint is higher than that of aluminum. Because it is about three digits worse (1000
The heat supply amount in the horizontal plane is small. Therefore, the heat flow path to the hand is considered to be dominated by the influence of the heat flow in the vertical direction indicated by the thick arrow as shown in FIG.
The amount of heat flow to the hand is calculated by the following formula.
Approximate evaluation can be made using the heat transfer rate U in the dimensional direction as an index. U = λ _p / d _p (4)

Based on this assumption, the heat transfer coefficient (a parameter indicating the ease of passing heat) of the surface treatment member in the one-dimensional model in the vertical direction is estimated below.

First, as a comparison target, the case of a normal coating treatment without using a foam material is roughly estimated. The thermal conductivity λ _p1 of the paint used for ordinary coating is considered to be on the same order as the thermal conductivity of epoxy or acrylic resin, and is set to 0.15 (W / mK).
When a film thickness of 40 μm is used as the coating film thickness d _p1 , the heat transmittance is 3750 (W / m ² K) from the following equation. U ₁ = λ _p1 / d _p1 = 0.15 / 40 × 10 ⁻⁶ = 3750 (W / m ² K)

Next, the effect of foam coating will be roughly estimated. Effective thermal conductivity lambda _p2 of the foam layer, above the thermal conductivity (0.025 thermal conductivity _{λ a (W / mK))} 0.15 (W / mK) of the paint and air 50% And the combined thermal conductivity is 0.088 (W / mK) calculated from the parallel thermal resistance. The coating thickness d _p2 is
A film thickness of 200 μm is used. From the calculation result of the following equation, the heat transmittance is 440 (W / m ² K). U ₂ = λ _p2 / d _p2 = 0.088 / 200 × 10 ^-6 = 440 (W / m ² K)

As described above, the foam coating contains a large amount of air having a low thermal conductivity, so that the combined thermal conductivity is lowered and the foamed layer can make the coating film thicker. The order of heat transfer rate is about 1
It is reduced by an order of magnitude (approximately 1/10). This appears as an effect of reducing the heat flow from the aluminum to the hand, that is, a difference in the tactile characteristics between the normal paint and the foam paint. That is,
When viewed from the hand, the heat transfer rate between the aluminum metal surface and the finger is the dominant heat transfer parameter, but this foam layer significantly reduces the heat transfer rate and reduces the heat flow to the hand Is done. By applying this foam paint, 3
The heat transmittance of the coating film, which was 750 (W / m ² K), was 440
(W / m ² K), which makes it difficult for heat inside the housing to pass through. However, the heat transfer coefficient from the housing surface during natural air cooling in a portable electronic device is as small as about 10 (W / m ² K) or less.
When the heat transmittance of the coating film decreased to 440 (W / m ² K), in the overall heat radiation system, a heat transmittance of 10 (W / m ² K) corresponding to natural air cooling on the housing surface was clearer. Therefore, the temperature rise inside the housing due to the increase in the thickness of the coating film is negligible and is not a problem.

Embodiment 5 FIG. FIG. 7 shows the bead-based paint 11
Is applied several times in layers to increase the thickness of the coating film. A porous structure containing a large amount of air is formed in the coating film, and the same effect is exerted. A bead-based resin coating material and a multi-layer plate glass may be used.

Embodiment 6 FIG. FIG. 8 shows a combination of the fourth embodiment and the fifth embodiment. The surface hardness is increased and compensated for by the top coating of the bead-based paint 11 on the decrease in the restoring force peculiar to the foam material. A coating with high hardness is applied to the surface of the coating, which has a porous structure inside and has a weak restoring force due to the formation of an air layer and is easily scratched, to enhance the coating strength and reinforce it. is there. The major difference between bead-based paints and conventional paints lies in the way the paint pigment components are blended. In the conventional paint, the pigment is dispersed in the paint as it is. On the other hand, the bead-based paint contains a large amount of “a pigment component wrapped in a special resin and formed into fine beads (beads)” in the paint. These beads produce a wide variety of colors. The design range of bead-based paints in which colored beads of different diameters are combined in a well-balanced manner is wide. For example, a suede-like coating film has a large brushing feeling and particle feeling. In addition to the velvet-like, backskin-like, and shimofuri-like hues of small particles, there are also paints with a flat paint surface containing finely powdered natural collagen fibers. In the structure shown in FIG. 8, the absolute condition is that the thickness of the undercoating coating film is within a predetermined range in order to provide a warm touch feeling. The standard film thickness recommended by paint maker for undercoat paint is generally 2
Although the thickness is 0 to 30 μm, in order to “provide a warmer finger touch” that cannot be obtained by using only the top-coat bead-based coating, a coating in which the thickness of the undercoat coating film is 45 to 80 μm is applied. Further, by setting the film thickness of the top coat to 45 to 60 μm, a suede-like appearance can be exhibited and a warm touch can be obtained.

It is effective to combine and combine the above-described embodiments according to the purpose, and it is effective to perform a surface treatment method suitable for various purposes as appropriate. Hereinafter, various combinations described in order from the upper layer to the lower layer will be exemplified. (1) First paint 6 Second paint 6 (the same or a different kind of paint as the first paint) Metal housing sheet metal 1 (2) First resin coating 7 Second resin coating 7 ( Metal coating sheet metal 1 (3) Paint 6 (or paint 6 mixed with heat insulating filler 8 or granular heat insulating material 9 or foam material 10) Resin Coating material 7 (or resin filler material 7 mixed with heat insulating filler 8 or granular heat insulating material 9 or foam material 10) Paint 6 (or paint material 6 mixed with heat insulating filler 8 or granular heat insulating material 9 or foam material 10) Metal casing sheet metal 1 (4) Resin coating material 7 (or heat insulating filler 8 or resin coating material 7 mixed with granular heat insulating material 9 or foam material 10) Paint 6 (or heat insulating material filler 8 or granular break) Paint 6 mixed with material 9 or foam material 10) resin coating material 7 (or resin filler material 8 mixed with heat insulating filler 8 or granular heat insulating material 9 or foam material 10) metal housing sheet metal 1 (5) bead system Paint 11 Heat-insulating filler 8 or resin coating material 7 mixed with granular heat-insulating material 9 or foam material 10 Paint 6 Metal housing sheet metal 1 (6) Heat-insulating material filler 8 or granular heat insulating material 9 or foam material 10 mixed Resin coating material 7 Bead paint 11 Paint 6 Metal casing sheet metal 1 (7) Paint 6 Bead paint 11 Metal casing sheet metal 1 (8) Resin coating material 7 Bead paint 11 Metal casing sheet metal 1 Is possible. In addition, using the processing described in the above-described first to sixth embodiments, if the surface of the coating film is intentionally made uneven, the contact area with the hand is reduced, and the effective heat transfer coefficient to the hand is reduced. Since the effect is added, more effective sensible temperature processing can be realized.

Embodiment 7 FIG. FIG. 9 shows an appropriate combination of the surface treatment methods described in Embodiments 1 to 6 described above for the purpose of complementing sink marks, hot water wrinkles, and scratches on the surface during molding of the metal casing by die casting. It is an example.
In the case of a metal casing formed by die-casting of magnesium (Mg) or aluminum (Al), small sink marks or hot lines 12 are generated on the surface during injection molding, and it is common to perform repair with putty. The sink marks are also called shrinkage cavities, and are dent defects on the surface during casting. Hot water wrinkles are surface wrinkles formed when molten metal flows into a mold cavity during casting. If the thick film coating method as in the above-described first to sixth embodiments is applied, there is also an eye-catching effect, and sink marks and hot water lines 12 are concealed. It is no longer necessary to reduce the number of processes, improve quality,
It is effective for cost reduction.

In general electronic equipment, the temperature of the metal housing sheet metal 1 rises due to the heating from the heating element 3.
By arranging paint and resin coating material in multiple layers, mixing heat insulating material in paint or resin coating material at a high rate and applying it to the housing surface, it creates a heat insulating layer structure in the coating film, Mixing a heat insulating material is effective in reducing the heat flow to the hand. It is also effective to mix a foaming material to form a foamed structure and to form an uneven structure on the surface of the coating film in order to reduce the contact area and reduce the heat flow to the hand. In addition, by applying a paint or resin coating material mixed with a large number of heat insulating materials or air voids to the metal housing that has become hot, the effective thermal conductivity in the coating film can be reduced, and the tactile temperature can be greatly improved can do. In addition, by consciously subjecting the surface of the housing to the unevenness processing, the contact area when the hand touches is reduced, and the effective heat transfer coefficient to the hand can be reduced. In other words, the heat flow to the hand is reduced, and the heat flow flowing into the hand at the moment of touch, which is peculiar to the metal surface, and the heat flow supplied thereafter can be reduced, so that the tactile temperature can be reduced.

The portion to be subjected to the surface treatment may be the entire member or a portion where the temperature of the member changes (for example, FIG. 1).
(Elliptical frame portion) or only the surface portion where the member may come into contact with the hand.

Example From the viewpoint of the above-mentioned first to third trial production guidelines, it was found that among the above-mentioned various coating examples, a countermeasure method of forming a foamed layer by mixing a foaming material into the paint was promising. This time, the thermal expansion microcapsules containing low boiling hydrocarbons were used as the foam. In this measure, the coating film expands and expands during baking coating, and porous air bubbles can be included, so that the effective thermal conductivity in the coating film decreases. Further, there is also an effect that a coating film can be made thicker than usual by the foaming action. Also, the foaming effect is effective from the viewpoint of promoting unevenness. In addition, it is effective to provide a top coating layer made of a bead or paint having higher hardness than the foam layer on the foam layer. Hereinafter, the embodiment shown in FIG. 8 will be described. The present invention can be applied not only to a metal housing but also to a housing using a material having high thermal conductivity. FIG.
FIG. 9 is a diagram showing 18 specific examples having the surface treatment structure shown in FIG. 8. FIG. 13 is a diagram showing evaluation results for combinations of 18 types of undercoat and overcoat. The example shown in FIG. 13 is an undercoat paint as shown in FIG. 13 for a magnesium plate or an aluminum plate to which a wash primer has been subjected to a chemical coating treatment for rust prevention based on the coating flowcharts of FIGS. And the evaluation results in the case of applying a top coat. FIG. 16 is a diagram showing a cross section of the coating film. “Tactile sensitivity” in the column of the evaluation result indicates the preference when the painted surface is touched with a finger. A coated surface that is not too rough and slippery and provides a moderate and warm finger touch is considered to be good. Also, "Tactile temperature"
The term “heat” indicates the heat received by a finger from the painted surface when the painted surface is touched with the finger. The “hardness” is the hardness determined from the degree of scratching when trying to damage the painted surface with a pencil lead having a hardness of B, HB, F, or H.
A hardness of H or higher is judged as acceptable, and other soft hardness is judged as unacceptable. Next, as shown in FIG. 17, the "adhesion" indicates whether or not the coating is peeled off when a cross-cut is made at 1 mm intervals on the coating surface and an adhesive tape is applied and peeled off. is there. In the evaluation results, a circle indicates good. In addition, the mark “x” indicates that it is not possible. The symbol Δ indicates between good and bad. Note that, in the evaluation results, a column in which no ○, ×, or Δ mark is entered indicates that no evaluation was performed.

A characteristic point in FIG. 13 is the evaluation result for the hardness. Although 1% to 5% of the foaming material is added to the undercoat paint, if the amount of the foaming material is increased, the restoring force peculiar to the foaming material is reduced, so that the hardness is lowered. If more than 5% of the foaming material is added, the hardness is further reduced. The hardness was satisfied by N
o. In other words, the hardness H was not satisfied. In order to compensate for the lowering of the restoring force of the undercoat having a foam material, it is necessary to satisfy the hardness H in many cases, although the surface hardness is increased by top-coating a bead-based paint as a top coat. Can not. In principle, the lower the amount of foam added, the higher the hardness. N
o. In the case of No. 16, the addition amount of the foaming material is 1%. In particular, it is important to carry out coating with high hardness in portable electronic devices. If the hardness is soft, the coating is likely to be damaged, which lowers the commercial value. Regarding the tactile sensitivity, no. In case 1, the conventional paint was used as the top coat, so that the mark was x, but in other cases, it was marked with △ or ○. Regarding the “tactile temperature”, since the foaming material was added to the undercoat and the bead-based paint was used for the topcoat, the No. 1 and No.
2 and No. Except for the case of No. 4, it was found that it had almost good touch temperature characteristics. That is, it has been found that the coating film structure as shown in FIG. 16 has an effect of reducing the temperature transmitted to the finger when touched by the finger. Next, regarding the "adhesion", the adhesion between the undercoat paint and the topcoat paint became a problem in particular, and when the added amount of the foaming material was 3% or 5%, the adhesion was poor. However, when the added amount of the foaming material was 1%, the coating film of the top coat was good without peeling from the undercoat. As described above, in the case shown in FIG.
6 and no. 9 and no. No. 16 is a generally desirable case. 16 is optimal. In addition, No. 17 and N
o. 18 cases are next. Although not shown in FIG. 13, in the case of the foamed layer coating film made of only the undercoat paint, the surface of the coating film had too many irregularities, and the “touch sensitivity” was rejected, and the restoring force decreased due to the foaming material. Causes the hardness to be rejected. Further, in the case of a coating film made of only the top coating material (bead-based coating material), the "touch temperature" is rejected as in the case of the conventional coating material. Thus, the evaluation result shown in FIG.
This is obtained because both the foam layer and the top coating layer are present. As can be seen from FIG. 13, when the added amount of the foaming material is 5% or less or less than 5%, it is possible to obtain a coating satisfying the tactile temperature. When the hardness and the adhesion are satisfied in addition to the tactile temperature, the amount of the foamed material is preferably 1% or less. FIG.
No. shown in FIG. 6 and no. 9 and no. It is a figure which shows the brand name of the undercoat paint and top coat paint in case of 16. No. 6 and no. 9 and no. The case of No. 16 shows a good case where the addition amount of the foaming material was 1%. In the market as shown in FIG. 18, by using a commercially available paint, it is possible to obtain a paint that has a moderate touch temperature and good touch sensitivity or hardness or adhesion to a portable electronic device. Can be. The three cases shown in FIG. 18 show the case where a foaming material is added to the primer. Fig. 1 shows the corrosion-resistant magnesium plate.
The use of the undercoat paint No. 8 means that a foaming material is added in the first coating of the magnesium plate, that is, in the coating of the primer.
By thus putting the foam material in the primer, the coating is completed by two coatings of the undercoating and the topcoating. The coating process is simplified as compared with the case where the primer treatment is performed, the intermediate coating treatment with the addition of the foaming material is performed, and then the top coating treatment is performed. Also, as shown in FIG. 18, it is desirable to select the undercoat and the overcoat from the same manufacturer. The reason is that products from the same manufacturer can obtain higher "adhesion". In addition, the thickness of the undercoat film is 45 to 80 μm,
The thickness of the top coating layer is 45 to 60 μm,
When the thickness of the entire coating film is 200 μm or less, generally good results are obtained. The best case among the 18 combinations shown in FIG. In this case, the thickness of the undercoat film is 5
9.9-66.6 μm, and the total coating thickness is 13
When the thickness is 5 to 155 μm, good results are obtained in terms of touch temperature, hardness, and adhesion.

Next, the results of experimentally evaluating the effect of the foam coating will be described. Verification Experiment 1 (Evaluation of Temperature Rise Characteristics) As shown in FIG. 19, the temperature rise characteristics when a rubber prism simulating a hand was brought into contact were measured. The temperature sensor was embedded at a depth of 0.5 mm in the rubber simulated hand. The specimen is 105 x 150 x 0.3 mm aluminum (A
l) Aluminum of 105 × 150 × 0.3 mm (A
l) No. on the base of the plate This is Sample B, which was subjected to foam coating and indicated as No. 16. The sample was heated by a heater installed 4 mm below, and the surface was kept at a constant temperature of 50 ° C. As a result, as shown in FIG. 20, it was confirmed that the contact temperature rise profile of the foamed coating tended to be slower than that of the normal epoxy coating.

Verification Experiment 2 (Evaluation of Report of Touch Temperature Level) Next, the touch temperature characteristics when the sample was actually touched by a human were evaluated from reports of nine subjects. As shown in FIG. 21, in this verification, in addition to samples A and B used in Experiment 1, A
Sample C normally coated on a BS resin plate was added for comparison. The sample had a surface temperature of 46 at room temperature of 25 ° C.
It heated by the apparatus of experiment 1 so that it might be fixed at ° C. Sample 3
FIG. 22 shows the total result of having the subject declare the rank / level that felt hot when the type was touched by hand. Sample A felt clearly hotter than the other Samples B and C (A
>> B, A >> C) all responded. On the other hand, it was confirmed that the touch temperature of Sample B was significantly lower than that of Sample A, and the degree was close to that of Sample C. Samples B and C were difficult to distinguish, and there were cases where the reporting order was reversed by the subjects (B> C, C>
B, B = C).

[0055]

The effects of the present invention are listed below. Compared with the conventional countermeasures such as pasting of the heat insulating material and flocking, the processing procedure is easier and the countermeasures can be taken on an extension of the conventional coating method, so that the productivity is increased and the effect on cost reduction is great.

This special processing alleviates the tactile temperature problem, which has been one of the problems in using the metal housing.
The applicability of the metal housing expands. Along with this, small, lightweight, thin and
A strong housing structure can be realized.

Further, when the surface is subjected to the unevenness processing,
Noppel feeling of the painted surface peculiar to metal is eliminated, and there is a merit in design.

Further, since the use of the thick film coating has an effect as a measure, the sink marks and hot lines formed at the time of molding the housing by die-casting are concealed. There is no need to perform putty repair again, which is effective in reducing the number of processes, improving quality, and reducing costs.

In addition, since a porous film is formed on the surface of the housing by the present surface treatment, vibration and impact resistance are increased. In addition, since a sound absorbing / insulating effect is also provided, a soundproofing function comes out.

[Brief description of the drawings]

FIG. 1 is a perspective view showing Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing Embodiment 1 of the present invention.

FIG. 3 is a sectional view showing Embodiment 2 of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing Embodiment 4 of the present invention.

FIG. 6 is a diagram showing a relationship between a coating film thickness and a tactile temperature according to Embodiment 4 of the present invention.

FIG. 7 is a sectional view showing a fifth embodiment of the present invention.

FIG. 8 is a sectional view showing Embodiment 6 of the present invention.

FIG. 9 is a sectional view showing Embodiment 7 of the present invention.

FIG. 10 is a sectional view showing a conventional countermeasure example 1.

FIG. 11 is a cross-sectional view showing a second conventional countermeasure.

FIG. 12 is a sectional view showing a third conventional countermeasure.

FIG. 13 is a diagram showing an embodiment of the present invention.

FIG. 14 is a flowchart showing a coating process for a magnesium plate of the present invention.

FIG. 15 is a flowchart showing a coating process for an aluminum plate according to the present invention.

FIG. 16 is a diagram showing a cross section of a coating film of the present invention.

FIG. 17 is a diagram showing a cross cut state of the present invention.

FIG. 18 is a diagram showing a trade name of the paint of the present invention.

FIG. 19 is a diagram showing an experimental verification device of the present invention.

FIG. 20 is a diagram showing a verification result of the present invention.

FIG. 21 is a view showing an experimental sample of the present invention.

FIG. 22 is a diagram showing experimental results of the present invention.

FIG. 23 is a conceptual diagram of heat flow when touched by a finger.

[Explanation of symbols]

Reference Signs List 1 metal housing sheet metal, 2 substrate, 3 heating element, 4 felt, 5 flocking pile, 6 paint, 7 resin coating material, 8 heat insulating material filler, 9 granular heat insulating material, 10
Foaming material, 11 bead-based paint, 12 sink marks and hot water lines formed during die casting.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Atsushi Fujita 2005-21 Endo, Fujisawa-shi, Kanagawa Prefecture Inside Fujix Co., Ltd. (72) Inventor Takeo Serizawa 2005-21 Endo, Fujisawa-shi, Kanagawa Prefecture Fujitsu Co., Ltd. (56) Reference Document JP-A-8-290509 (JP, A) JP-A-4-319433 (JP, A) JP-A-63-319085 (JP, A) JP-A-58-70865 (JP, A) 28419 (JP, A) “100th Anniversary Lecture Meeting of Thermal Engineering Symposium” Published by The Japan Society of Mechanical Engineers, July 15, 1997, pp. 75-76 (58) Field surveyed (Int. . ^7, DB name) B32B 1/00 - 35/00 B05D 1/00 - 7/26 H05K 5/00 - 5/06

Claims (10)

(57) [Claims] 1. A heat-generating element, a die-cast metal housing for housing the heat-generating element, and dissipating heat generated from the housed heat-generating element from inside the housing to outside of the housing by heat conduction. A portable electronic device comprising: a coating film applied to a surface of a metal housing; wherein the coating film is formed by applying a coating material containing 2% by weight or less of a foaming material and foaming the coating material; on the layer, and a foam layer high topcoating layer hardness than the coating film, radiating heat generated in the inside of the housing from the surface of the housing outside the housing
It is a coating film that maintains heat dissipation, and the human body
Reduces the amount of heat flowing into the human body when touching the surface,
A portable electronic device characterized by a coating film that relieves discomfort to the user. 2. The portable electronic device according to claim 1, wherein the coating material contains 1% by weight or less of a foaming material. 3. The portable electronic device according to claim 1, wherein the top coating layer is formed of a bead-based coating material containing beads. 4. The portable electronic device according to claim 1, wherein the coating material is one of a paint, a resin coating material, and a primer. 5. The portable electronic device according to claim 1, wherein the metal housing is made of one of aluminum, magnesium, an aluminum alloy, and a magnesium alloy. 6. The portable electronic device according to claim 1, wherein the thickness of the foam layer is 100 μm or less. 7. The portable electronic device according to claim 1, wherein the foam layer has a thickness of 45 to 80 μm. 8. The thickness of the top coating layer is 1
The portable electronic device according to claim 1, wherein the thickness of the portable electronic device is equal to or less than 00 μm. 9. The thickness of the top coating layer is 4
The portable electronic device according to claim 1, wherein the thickness is 5 to 60 m. 10. The portable electronic device according to claim 1, wherein the coating has an uneven surface.