JP5592582B1 - Pre-coated aluminum plate and heat sink for in-vehicle LED lighting - Google Patents

Abstract

The present invention provides a precoated aluminum plate material excellent in heat dissipation and a heat sink for in-vehicle LED lighting.
A pre-coated aluminum plate material 10 is used for a heat sink for in-vehicle LED lighting and has an aluminum plate material 20 and a resin-based coating 3A. The aluminum plate material 20 has a thermal conductivity of 150 W / m · K or more, and is made of resin. The system film 3A includes a thermosetting resin, a black pigment component, and an aggregate. The film thickness of the resin system film 3A is 5 to 15 μm, and the arithmetic average roughness Ra of the surface of the resin system film 3A is 1 to 3 μm, and the resin-based film 3A is a precoated aluminum sheet 10 having an integral emissivity in the infrared region with a wavelength of 3 to 30 μm of 0.80 or more at 25 ° C., and the precoated aluminum sheet 1 is a heat sink 1 for vehicle-mounted LED illumination formed by molding 10.
[Selection] Figure 1

Description

  The present invention relates to a pre-coated aluminum plate material for a heat sink for in-vehicle LED illumination for mounting a light emitting diode (LED) element, and a heat sink for in-vehicle LED illumination.

  Lighting that uses a light emitting diode (LED) element as a light source is gradually penetrating the market due to its low power consumption and long life. Among them, in-vehicle LED lighting such as automobile headlights has attracted particular attention in recent years.

  However, the LED element which is a light emitting source of this LED illumination is very weak to heat, and there is a problem that when the temperature exceeds the allowable temperature, the light emission efficiency is lowered, and further, the life is affected. In order to solve this problem, since it is necessary to dissipate heat at the time of light emission of the LED element to the surrounding space, the LED lighting is provided with a large heat sink.

  Many LED die heat sinks made of aluminum (including an aluminum alloy) are used, and Patent Documents 1 to 4 disclose heat sinks having typical configurations among these heat sinks. Is disclosed.

JP 2007-172932 A JP 2007-193960 A JP 2009-277535 A JP 2010-278350 A

In recent years, high power has been developed for in-vehicle LED lighting, and further improvement in heat dissipation is required for the in-vehicle LED lighting heat sink.
On the other hand, the heat sink for in-vehicle LED lighting is moving to a molded body formed by molding an aluminum plate material instead of the conventional aluminum die cast in order to improve productivity and reduce costs.
In order to improve heat dissipation with respect to a heat sink made of a molded body of an aluminum plate material, there has been a strong need for further improvement of heat dissipation from the characteristics of the aluminum plate itself constituting the heat sink and the surface of the plate material.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the precoat aluminum plate material excellent in heat dissipation, and the heat sink for vehicle-mounted LED illumination.

  As a result of investigations to solve the above problems, in order to lower the thermal resistance of the material, the thermal conductivity of the aluminum plate is set to a certain level or more, and a black film is formed on the surface of the molded body made of the aluminum plate. It is important to increase the emissivity by forming it, to reduce the thermal resistance as a film by making the film relatively thin, and to increase the emissivity by appropriately controlling the surface roughness of the film, etc. Obtaining knowledge, the present invention has been achieved.

  The present invention has the following configuration. The pre-coated aluminum sheet according to the present invention is used for a heat sink for in-vehicle LED lighting, and has an aluminum sheet and a resin-based film. The aluminum sheet has a thermal conductivity of 150 W / m · K or more, and the resin The system film includes a thermosetting resin, a black pigment component, and an aggregate. The film thickness of the resin system film is 5 to 15 μm, and the arithmetic average roughness Ra of the surface of the resin system film is 1 The resin-based film has an integral emissivity in an infrared region having a wavelength of 3 to 30 μm of 0.80 or more at 25 ° C.

  According to such a configuration, the pre-coated aluminum sheet is excellent in the thermal conductivity of the aluminum sheet and the film is relatively thin. However, the pre-coated aluminum sheet is excellent in radiation as a film and has excellent heat dissipation when used as a heat sink. Will be.

  In the precoated aluminum sheet according to the present invention, the crystal structure of the aluminum sheet is preferably fiber-like. According to such a configuration, a molded body with less surface roughness can be produced when the molding process is performed.

  A vehicle-mounted LED illumination heat sink according to the present invention (hereinafter appropriately referred to as a heat sink) includes a heat sink molded body formed by molding an aluminum wrought material, and a black film formed on the surface of the heat sink molded body. It is a heat sink for in-vehicle LED lighting, and the thermal conductivity of the aluminum wrought material is 150 W / m · K or more, the film thickness of the film is 5 to 15 μm, and the arithmetic average roughness of the surface of the film The thickness Ra is 0.5 to 3 μm, and the coating film is characterized in that an integrated emissivity in an infrared region having a wavelength of 3 to 30 μm is 0.80 or more at 25 ° C.

  According to such a configuration, the heat sink is excellent in the thermal conductivity of the aluminum wrought material and the film is relatively thin. However, the heat sink is excellent in radiation as the film, and excellent heat dissipation is ensured as the heat sink.

  Moreover, the film | membrane of the vehicle-mounted LED illumination heat sink which concerns on this invention is a resin-type film | membrane containing a thermosetting resin, a black pigment component, and an aggregate, The arithmetic mean roughness Ra of the surface of the said film | membrane is 1-3 micrometers. It is preferable that According to such a configuration, the durability of the resin film is improved, and the radioactivity as the film is further improved.

  The pre-coated aluminum sheet material of the present invention is excellent in moldability and can provide a heat sink for in-vehicle LED lighting excellent in heat dissipation. Moreover, the heat sink for vehicle-mounted LED illumination of this invention is excellent in heat dissipation.

(A) is sectional drawing which shows typically the structure of the heat sink for vehicle-mounted LED illumination concerning this invention, (b) is sectional drawing which shows typically the structure of the precoat aluminum plate material of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
≪Heat sink≫
As shown to Fig.1 (a), the heat sink 1 which concerns on this invention is used for the vehicle-mounted LED lighting 100, and is comprised from the heat sink molded object 2 formed by shape | molding the aluminum extending | stretching material. Some embodiments of the invention include a coating 3 formed on the surface of the heat sink molded body 2. The heat sink 1 is used to dissipate heat generated from the LED element 4.
Each configuration will be described below.

<Heat sink molding>
The heat sink molded body 2 is made of aluminum formed by molding an aluminum wrought material. The term “aluminum wrought material” is intended to differentiate it from the current aluminum die cast, extruded material, resin, iron and other metals by limiting to wrought material. Among the aluminum wrought materials, an aluminum plate material excellent in productivity, precoat processability and the like is preferable. Hereinafter, the aluminum plate material will be described.

<Aluminum plate material>
The aluminum plate material used in the heat sink 1 for vehicle-mounted LED lighting of the present invention is made of aluminum or an aluminum alloy, and the aluminum plate material (aluminum plate material or aluminum alloy plate material) used in the present invention is not particularly limited. And can be selected based on the product shape, molding method, strength required at the time of use, and the like. Generally, as the aluminum plate material for press forming, a non-heat treatment type aluminum plate, that is, a 1000 series industrial pure aluminum plate, a 3000 series Al-Mn alloy plate, a 5000 series Al-Mg series alloy. Some 6000 series Al—Mg—Si alloy plates, which are plates or heat treated aluminum plates, are used. However, since the heat sink molded body 2 has a thermal conductivity of 150 W / m · K or more as will be described later, the aluminum plate material is almost limited to 1000 series, some 3000 series, and some 6000 series.

The aluminum plate material used in the heat sink 1 for in-vehicle LED lighting of the present invention is preferably 1000 series, and the particularly preferred composition is as follows.
(Preferable range of Si content: 0.03 to 1.00% by mass)
Si has the effect of being dissolved in the matrix and increasing the strength of the aluminum alloy plate, and the effect is improved as the Si content is increased. If the Si content is 0.03% by mass or more, the effect is more sufficient, and if it is 1.00% by mass or less, the thermal conductivity is improved and the performance as a heat sink material is improved.

(Preferable range of Fe content 0.10 to 0.80 mass%)
Fe has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Fe content increases. If the Fe content is 0.10% by mass or more, the effect is more sufficient, and if it is 0.80% by mass or less, the thermal conductivity is improved and the performance as a heat sink material is improved.

(Preferable range of Cu content 0.30% by mass or less)
Cu has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Cu content is increased. If Cu content is 0.30 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

(Preferable range of Mn content 0.20% by mass or less)
Mn has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Mn content increases. If Mn content is 0.20 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

(Preferable range of Mg content 0.20% by mass or less)
Mg has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Mg content increases. If Mg content is 0.20 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

(Preferable range of Cr content is 0.10 mass% or less)
Cr has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Cr content increases. If Cr content is 0.10 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

(Preferable range of Zn content 0.20% by mass or less)
Zn has the effect of increasing the strength of the aluminum alloy plate by dissolving in the matrix, and the effect is improved as the Zn content increases. If Zn content is 0.20 mass% or less, thermal conductivity will improve and the performance as a heat sink material will improve.

(Preferable range of Ti content is 0.10 mass% or less)
Ti has the effect of refining and homogenizing (stabilizing) the aluminum alloy cast structure, and has the effect of preventing casting cracks during ingot formation of the slab for rolling. If the Ti content exceeds 0.10% by mass, the effect is saturated. Moreover, if it is 0.10 mass% or less, thermal conductivity will improve. Therefore, it is unnecessary to contain an amount exceeding 0.10% by mass.

[Thermal conductivity]
Since the use of the heat sink molded body 2 is the heat sink 1, heat dissipation is required. In order to ensure the desired heat dissipation in the present invention, the thermal conductivity of the aluminum plate material constituting the heat sink molded body 2 needs to be 150 W / m · K or more. Preferably, it is 200 W / m · K or more. The upper limit value is not particularly specified, but is preferably 240 W / m · K or less from an economical viewpoint. Examples of the aluminum alloy having such characteristics include alloys having a specific product number and composition as described above.
The thermal conductivity can be measured by, for example, a laser flash method.
The aluminum plate material used for the heat sink molded body 2 may be a pre-coating material or an after-coating material. Further, anodizing treatment may be performed on the molded body 2 after processing, but a precoat material is preferable from an economical viewpoint.

[Crystal structure]
The aluminum plate material preferably has a fiber structure in crystal structure. “Fibrous” refers to a state having an elongated structure in which the aspect ratio between the major axis direction and the minor axis direction of the crystal structure is 10 times or more. If the crystal structure of the aluminum plate material is a fiber, it is preferable because the surface of the processed part of the molded body becomes smooth when bending is performed in order to produce the molded body. Among the fiber-like structures, those in which the length in the minor axis direction of the crystal structure is 5 to 50 μm are preferable because the roughened surface of the processed part becomes smaller. An aluminum plate having a grainy coarse crystal structure is generally not preferable because the surface roughness of the processed portion becomes large.
Discrimination of the crystal structure of the aluminum plate can be performed with a microscope. When discriminating the crystal structure with a microscope, a cross section of aluminum parallel to the direction in which the aluminum is extended by rolling (rolling direction) is observed.

A preferable annealing condition for realizing a fiber-like structure will be described.
The annealing conditions for realizing a fiber-like structure and providing good bending workability are preferably 130 to 280 ° C. and 1 to 10 hours. When the annealing temperature is less than 130 ° C., the characteristics vary in the annealed aluminum coil. On the other hand, when the annealing temperature exceeds 280 ° C., recovery / recrystallization proceeds, yield strength decreases, and crystal grains become coarse. Also, when the annealing time is less than 1 hour, the characteristics in the aluminum coil vary as in the case where the temperature is low. On the other hand, if it exceeds 10 hours, factory productivity will fall.

<Film>
The heat sink molded body 2 of the present invention has a film 3 formed on the surface thereof. By forming the film 3 on the surface of the heat sink molded body 2, the durability and radiation of the heat sink molded body 2 can be improved. However, since the thermal resistance during heat transfer increases due to the formation of the coating 3, it is preferable that the thickness of the coating 3 is relatively small. When the film thickness of the film 3 is less than 5 μm, good emissivity cannot be secured. On the other hand, even if the film thickness of the film 3 exceeds 15 μm, the emissivity is no longer improved, and conversely, the thermal resistance of the film 3 increases. Therefore, the film thickness of the film 3 is set to 5 to 15 μm. More preferably, the film 3 has a thickness of 7 to 12 μm. The film thickness of the film 3 can be measured by, for example, an eddy current film thickness meter isoscope (ISOSCOPE: registered trademark).

Here, the surface of the heat sink molded body 2 means at least one surface of the surface of the heat sink molded body 2 and includes a so-called front surface and back surface.
Although it does not specifically limit as a kind of membrane | film | coat 3, There exist resin-type membrane | film | coats, such as a precoat, an aftercoat, and an anodic oxidation, and an inorganic-type membrane | film | coat.

  The film 3 needs to be black. This is because if the color tone of the film 3 is black, the heat dissipation rate is increased, and the heat dissipation as the heat sink 1 is further improved. In order to make the film 3 black, it is preferable to contain a black pigment component when the film 3 is a resin-based film described later. When the film 3 is an inorganic film, black anodization is preferable.

[Arithmetic mean roughness (Ra)]
In the present invention, as described above, the thermal resistance is lowered as much as possible while maintaining the emissivity by setting the film 3 to be thin. However, when the thickness of the coating 3 is reduced, the emissivity generally decreases. Therefore, in order to compensate for the decrease in emissivity, the surface roughness of the coating 3 is set to be large. When the surface of the film 3 is rough to some extent, the surface area is increased and the emissivity can be increased.
When the arithmetic average roughness Ra of the surface of the film 3 is less than 0.5 μm, it is difficult to ensure good emissivity. On the other hand, when the arithmetic average roughness Ra of the surface of the film 3 exceeds 3 μm, the surface becomes too rough, and a fine gap is easily formed between the LED element 4 and the heat conduction between the LED element 4 and the heat sink 1 is reduced. Damaged. Therefore, the arithmetic average roughness Ra of the surface of the film 3 is set to 0.5 to 3 μm. The arithmetic average roughness Ra of the surface of the film 3 is more preferably 1 to 3 μm, and further preferably 1 to 2 μm.

  The method of adjusting the arithmetic average roughness Ra of the surface of the film 3 is to change the method and degree of surface polishing of the aluminum plate before forming the film, roughen it with shot blasting, or aggregate the film as described later. However, a method of adding aggregate to the film is preferable.

The arithmetic average roughness (Ra) is measured using a commercially available surface roughness measuring instrument. For example, a surf coder or the like can be used.
The probe of the surface roughness measuring instrument is scanned in a direction perpendicular to the rolling direction with respect to the test piece, and measured as arithmetic average roughness (Ra) described in JIS B0601.

The film 3 is preferably a thermosetting resin. Examples of the thermosetting resin include two or more types selected from polyester resins, epoxy resins, phenol resins, melamine resins, urea resins, and acrylic resins, and the hydroxyl groups, carboxyl groups, glycidyl groups, and amino groups that both resins have. , And a combination in which isocyanate groups and the like are chemically bonded to each other. When two or more kinds of such combinations of resins are included, one resin and the other resin undergo thermosetting reaction as a main agent and a curing agent, and thus become a thermosetting resin. When the thermosetting reaction does not proceed sufficiently by the combination, it may be combined with a curing agent such as an isocyanate compound.
When these resins are included alone (for example, when a polyester resin is used alone), the coating 3 may be melted when the heat sink 1 is used. In this case, since the adhesive force between the heat sink 1 and the LED element 4 is reduced, the durability of the heat sink 1 may be reduced. However, even if the resin is used alone, it can be made into a thermosetting resin having sufficient heat resistance and adhesion by separately combining with a curing agent such as an isocyanate compound.

  Among film combinations that combine two or more types of resin components, for example, amino-cured polyester resins, isocyanate-cured polyester resins, melamine-cured polyester resins, phenol-cured epoxy resins, urea (urea) -cured epoxy resins, etc. Is more preferable because heat resistance and adhesion are improved. In addition, modified resins such as acrylic-modified epoxy resins and urethane-modified polyester resins can also be suitably used.

  As described above, the black pigment component is used to increase the emissivity by making the resin film black. Specific examples of the black pigment component include carbon-based materials such as carbon black and graphite, and metal oxide-based materials such as copper, manganese, and iron. About 3-50 mass% of black pigment components are added with respect to the resin material which forms a membrane | film | coat.

  The aggregate is used to control the arithmetic average roughness Ra of the surface of the coating 3 within the predetermined range. Specific examples of the aggregate include organic aggregates typified by crosslinked acrylic beads and crosslinked urethane beads, inorganic aggregates typified by glass beads, and the like. The average particle diameter of the aggregate is preferably about 3 to 50 μm. The aggregate is added in an amount of about 3 to 30% by mass, as necessary, with respect to the resin material that forms the film.

[Integrated emissivity]
In the present invention, the coating 3 has an integral emissivity in the infrared region having a wavelength of 3 to 30 μm of 0.80 or more at 25 ° C. The emissivity is a proportional coefficient obtained by dividing the infrared radiation from the object surface by the infrared radiation from the black body surface, and is defined for light of a specific wavelength at a specific temperature. Possible numerical values range from 0 (white body) to 1 (black body). The larger the number, the greater the infrared radiation. The integral emissivity is obtained by integrating this in a certain wavelength range. According to Planck's radiation type, the wavelength of infrared rays that can be generated in the practical temperature range of 0 to 100 ° C., in the vicinity of room temperature, which is the temperature range of the present invention, is in the range of 3 to 30 μm focusing. In other words, infrared light in a wavelength region that is out of the range of this wavelength region may be ignored. For these reasons, the present invention is limited to infrared rays in the wavelength region of 3 to 30 μm at 25 ° C.

  If the integral emissivity of infrared rays at a wavelength of 3 to 30 μm with respect to the coating 3 is less than 0.80 at 25 ° C., the ability to emit heat as infrared rays from the surface of the coating 3 is lowered, and the ability to cool the product is insufficient. To do. Therefore, the heat dissipation of the heat sink 1 is reduced. The integrated emissivity in the infrared region having the wavelength of 3 to 30 μm is more preferably 0.85 or more, and further preferably 0.90 or more. Further, the upper limit value is not particularly defined, but is preferably 0.99 or less from an economical viewpoint. The integral emissivity of infrared rays at a wavelength of 3 to 30 μm can be controlled by combining the color, film thickness, surface state, film type, and the like of the film.

  The integral emissivity of infrared rays with respect to the film 3 at a wavelength of 3 to 30 μm can be measured using a commercially available simple emissometer, or using a Fourier transform infrared spectrophotometer (FTIR) or the like. It can be measured. For example, it can be measured using an emissivity D & S AERD apparatus manufactured by Kyoto Electronics Industry Co., Ltd.

[Others]
The film 3 can contain a small amount of a colorant and additives imparting various functions within a range where the effects desired by the present invention are achieved. For example, in order to further improve the moldability, for example, a lubricant such as polyethylene wax, carnauba wax, microcrystalline wax, lanolin, Teflon (registered trademark) wax, silicone wax, graphite lubricant, molybdenum lubricant, etc. One, two or more can be contained. In addition, as the conductive fine particles for imparting conductivity required for securing the earth required in electronic devices, for example, metal fine particles including nickel fine particles, metal oxide fine particles, conductive carbon, graphite, etc. One, two or more can be contained. Furthermore, when antifouling property is required, a fluorine compound or a silicone compound may be contained. In addition, antibacterial agents, fungicides, deodorants, antioxidants, ultraviolet absorbers, rust preventive pigments, extender pigments and the like can be included as long as the desired effects of the present invention are exhibited.

≪Pre-coated aluminum sheet≫
As shown in FIG.1 (b), the precoat aluminum board | plate material 10 which concerns on this invention is used for the heat sink for vehicle-mounted LED lighting, The resin-type membrane | film | coat 3A formed in the aluminum plate material 20 and the surface of the aluminum plate material 20 And. The aluminum plate 20 has a thermal conductivity of 150 W / m · K or more, the resin-based film 3A includes a thermosetting resin, a black pigment component, and an aggregate. The film thickness of the resin-based film 3A is 5 15 μm, the arithmetic average roughness Ra of the surface of the resin film 3A is 1 to 3 μm, and the resin film 3A has an integrated emissivity of 0.80 at 25 ° C. in the infrared region having a wavelength of 3 to 30 μm. It is the above, It is characterized by the above.
The thermal conductivity of the aluminum plate 20, the components of the resin film 3 </ b> A, the film thickness, the arithmetic average roughness Ra, and the integral emissivity are as described above.

  The crystal structure of the aluminum plate 20 constituting the precoated aluminum plate 10 is preferably fiber-like. As described above, if the crystal structure of the aluminum plate 20 is a fiber, when the molding process is performed to produce a molded body, the rough surface of the processed portion of the molded body is reduced, and the precoated film It is possible to prevent cracks from occurring.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the scope of the present invention.
For example, a surface treatment film (not shown) may be provided on the surface of the aluminum plate material 20 by surface treatment.

<Pretreatment>
The surface of the aluminum plate 20 is preferably subjected to a ground treatment in order to improve the adhesion with the resin-based film 3A. As a preferable base treatment, a conventionally known reactive type base coat and coating type base coat containing Cr, Zr or Ti can be used. That is, a phosphoric acid chromate film, a chromate chromate film, a zirconium phosphate film, a zirconium oxide film, a titanium phosphate film, a coating type chromate film, a coating type zirconium film, and the like can be used as appropriate. Organic-inorganic hybrid-type ground treatment coatings obtained by combining these coatings with organic components may also be used. In recent years, there has been a tendency to dislike hexavalent chromium due to the trend toward environmental protection. It is preferred to use.

In the present invention, as the film thickness of the base treatment film, the amount of Cr, Zr or Ti contained in the base treatment film component to the aluminum plate 20 (metal Cr, metal Zr or metal Ti equivalent value) is, for example, Using a conventionally known fluorescent X-ray method, it can be measured relatively easily and quantitatively. Therefore, quality control of the precoated aluminum sheet 10 can be performed without impeding productivity. In addition, it is preferable that it is 10-50 mg / m < ² > as a metal Cr, metal Zr, or metal Ti conversion value as an adhesion amount of a base-treatment film. When the adhesion amount is 10 mg / m ² or more, the entire surface of the aluminum plate 20 can be uniformly coated, and the corrosion resistance is improved. Moreover, if it is 50 mg / m < ² > or less, when the precoat aluminum plate material 10 is shape | molded, it will become difficult to produce a crack in the membrane | film | coat itself of a surface treatment.

  In addition, when productivity is not taken into consideration, a conventionally known process such as an anodizing process or an electrolytic etching process can be performed on the surface of the aluminum plate 20. When these treatments are performed, fine unevenness is formed on the surface of the aluminum plate member 20, and thus the adhesion of the resin-based coating 3A is greatly improved.

  Furthermore, when the corrosion resistance is not required so much and a simple method is desired, a method of only degreasing the surface of the aluminum plate material 20 may be used. As a method of degreasing, conventionally known methods such as degreasing with an organic drug, degreasing with a surfactant drug, degreasing with an alkaline drug, degreasing with an acid drug, and the like can be used. However, in the case of organic chemicals and surfactant chemicals, the degreasing ability is slightly inferior, and therefore degreasing with an alkaline chemical or an acid chemical is more productive. The degreasing capacity of alkaline chemicals can be controlled by the main component, concentration, and processing temperature of the alkali used. However, if the degreasing capacity is strengthened, a lot of smut will be generated, and subsequent washing with water will not be performed sufficiently. On the contrary, the adhesion of the resin-based film 3A may be lowered. In addition, when a variety containing a large amount of magnesium as an additive element is used for the aluminum plate member 20, with an alkaline chemical, magnesium may remain on the surface and the adhesion of the resin-based coating 3A may be reduced. Therefore, in this case, it is preferable to use or use an acid drug.

≪Pre-coated aluminum sheet manufacturing method≫
Next, an example of a method for producing a precoated aluminum sheet will be described with reference to FIG. 1 as appropriate.
About the manufacturing method of the precoat aluminum board | plate material 10, it does not restrict | limit in particular, After apply | coating the coating material containing the resin used as the base resin, and a hardening | curing agent on an aluminum board by a conventionally well-known method, it is by heating. It can be obtained by crosslinking reaction. In addition, it is preferable that the baking temperature at the time of baking a coating material shall be about 150-285 degreeC.

  Here, the coating may be applied by any means such as a brush, a roll coater, a curtain flow coater, a roller curtain coater, an electrostatic coating machine, a blade coater, or a die coater. At the same time, it is preferable to use a roll coater that is easy to work. When coating with a roll coater, the film thickness of the resin coating 3A is controlled by appropriately adjusting the conveyance speed of the aluminum plate 20, the rotation direction and rotation speed of the roll, the pressing pressure between the rolls (nip pressure), and the like. be able to.

  When manufacturing the heat sink 1 using the pre-coated aluminum plate material 10, the pre-coated aluminum plate material 10 may be formed into a shape of the heat sink 1 by performing a forming process such as a bending process by a conventionally known method.

Next, the present invention will be specifically described by comparing an example that satisfies the requirements of the present invention with a comparative example that does not satisfy the requirements of the present invention.
In this example, a heat sink for simulated vehicle-mounted LED lighting produced by bending aluminum alloy plates having different thermal conductivities and plate thicknesses was manufactured, and a “continuous lighting test” for confirming the heat dissipation performance was performed.

  An aluminum alloy having the composition shown in Table 1 was melted and cast into an ingot, and the ingot was chamfered and then subjected to a homogenization heat treatment at 480 ° C. The homogenized ingot was subjected to hot rolling, further cold rolling, and annealing treatment to obtain a rolled plate having a thickness of 1.0 mm. The rolling rate in cold rolling was 75%, and the annealing treatment was 240 ° C. for 4 hours. However, no. In only 25 examples, the annealing treatment was performed at 360 ° C. for 4 hours. As will be described below, a coating film was formed on the surface of this rolled plate to obtain a test material. Specifically, it is as follows.

  First, a commercially available 10 W LED lighting unit was purchased and dismantled, and a die-cast heat sink was taken out and used as a benchmark heat sink. Next, the shape of this benchmark heat sink was simulated, and heat sinks as examples and comparative examples manufactured from aluminum alloy plates were manufactured. In simulating the shape, particular attention was paid to faithfully reproducing only the shape of the LED element mounting portion and the joint portion required when reassembling the LED lighting unit. The reason is that a shape that cannot be incorporated into the lighting unit before disassembly is not practical. In consideration of productivity, the shape can be made from a single plate.

  The heat sink used as an Example and a comparative example was created as follows. First, the surface of a rolled plate made of an aluminum alloy having various plate thicknesses and thermal conductivities was subjected to phosphoric acid chromate treatment after weak alkali degreasing. Next, the coating material which becomes a component described in Table 2 of the Example after heating was applied to one surface with a bar coater so as to have a target thickness. Thereafter, temporary drying was performed at 100 ° C. for 60 seconds so that the crosslinking reaction was not accelerated. Next, a coating material having the same components as the first surface was applied to the opposite surface using the same bar coater. Then, the precoat aluminum plate was produced by heating the baking temperature at a material arrival temperature of 230 ° C. and a holding time in the furnace of 60 seconds. The pre-coated aluminum plate was 30 cm × 30 cm in size and was bent so as to have a shape almost equivalent to the die-cast heat sink (Test No. 1). To 24). When the LED element substrate and the heat sink were attached, they were joined using M3 bolts and nuts. In addition, commercially available silicon grease was applied to the bonding surface between the LED element substrate and the heat sink in order to increase the degree of contact.

The surface roughness was adjusted by a method of adding aggregates having different particle sizes while adjusting the addition amount. For the aggregate, cross-linked acrylic beads were used, but other resins and inorganic materials may be used.
Also, among the examples and comparative examples, after anodizing, the aluminum plate not subjected to any surface treatment was first subjected to surface roughness adjustment by polishing or shot blasting, and then bent into a predetermined shape. Then, sulfuric acid anodizing treatment was performed. The sulfuric acid was 15%, the voltage and current density, and the energization time were appropriately set to the conditions for obtaining a predetermined film thickness. In particular, for black anodization, sealing is performed after dyeing with a black dye.

[Thermal conductivity]
The thermal conductivity of the aluminum plate was measured by a laser flash method.

[Arithmetic mean roughness Ra]
The arithmetic average roughness (Ra) of the surface of the film was measured using a surface roughness measuring device (Surfcoder SE-30D manufactured by Kosaka Laboratory Ltd.). The probe was scanned in the direction perpendicular to the rolling direction with respect to the test material, and the arithmetic average roughness (Ra) described in JIS B0601 was measured. When the arithmetic average roughness (Ra) was 0.5 μm or more and 3 μm or less μm, it was judged as ◯, and when it was less than 0.5 μm or more than 3 μm, it was judged as x.

[Film thickness]
The film thickness of the film was measured using an eddy current film thickness isoscope (ISOSCOPE: registered trademark).

[Integrated emissivity]
The emissivity of the integral emissivity in the infrared region having a wavelength of 3 to 30 μm was measured under a temperature condition of 25 ° C. using an emissivity system D & S AERD apparatus manufactured by Kyoto Electronics Industry Co., Ltd. In addition, since the measurement wavelength range of this simple emissometer is 3-30 micrometers, the numerical value displayed becomes the integral emissivity defined by this invention.
When the integrated emissivity in the infrared region having a wavelength of 3 to 30 μm was 0.80 or higher at a temperature of 25 ° C., it was determined to be good, and when it was less than 0.80, it was determined to be poor.

[Heat dissipation: Continuous lighting test]
In-vehicle LED lighting is assumed to be used in various environments around the world, but lighting is actually used only at night. Under these conditions, it is considered that the most severe heat dissipation is required at night in the tropics. Therefore, assuming such an environment, a continuous lighting test was performed in a 35 ° C. environment.
A 10 W LED element was attached to each of the heat sinks of the benchmark, the example, and the comparative example to emit light, and the heat sink temperature immediately below the LED element when the temperature reached a steady state was measured. At this time, heat dissipation was good when the temperature was equal to or lower than the benchmark temperature, and heat dissipation was determined to be poor (x) when the temperature reached higher than the benchmark temperature. Among those having good heat dissipation, those that were lowered by 1 ° C. or more from the benchmark temperature were rated as ◯, and those that were less than 1 ° C. from the benchmark temperature were marked as Δ. In the present invention, it was recognized that the heat dissipation property was ○, and that Δ or × was equivalent to a comparative example.

[Weight saving]
This time, when making the benchmark die-casting heat sink into a plate, the weight reduction target was set to 50% of the benchmark separately from the performance. Therefore, when the weight of the heat sink of the prototype or comparative example manufactured as a prototype is 50% or less of the benchmark, it is light (◯), and when it exceeds 50%, it is not particularly lightweight, but there is no problem in use (△). It was.
These results are shown in Table 2. In addition, the underline part in Table 2 shows that it does not have the requirement or effect of this invention.

[appearance]
As an additional evaluation, the appearance of the bent processed part was evaluated. The appearance of the processed part was determined visually. A sample having a smooth appearance and a good appearance was marked with ◯, and a sample having a rough appearance with many irregularities was marked with Δ.

  As shown in Table 2, test no. 2, 3, 5, 6, 10, 14, 16 to 20, and 25 satisfy the configuration of the present invention, and show good performance in heat dissipation. However, test no. In No. 25, the crystal structure of the plate material was equiaxed, and the appearance of the processed part was slightly inferior to the plate material of the fiber-like crystal structure. On the other hand, test no. 1, 4, 7-9, 11-13, 15, 21-24 do not satisfy the configuration of the present invention, and the following results were obtained.

Test No. No. 1 was inferior in heat dissipation because the thermal conductivity was less than the lower limit.
Test No. No. 4 was inferior in heat dissipation because the thermal conductivity was less than the lower limit.
Test No. 7 and 9 were inferior in heat dissipation because the integral white emissivity in the infrared region of the film was less than 0.80 because the film was white.
Test No. Nos. 8 and 21 had film thicknesses exceeding 15 μm and were slightly inferior in heat dissipation.
Test No. No. 11 had an arithmetic average roughness of the surface of the coating of less than 0.5 μm, and was slightly inferior in heat dissipation.
Test No. In No. 12, the arithmetic average roughness of the surface of the coating exceeded 3 μm, and the heat dissipation was slightly inferior.
Test No. No. 13 had an integral emissivity in the infrared region of the film of less than 0.80 and was inferior in heat dissipation.
Test No. 15 is a test No. Similar to 12, the arithmetic average roughness of the surface of the coating exceeded 3 μm, and the heat dissipation was somewhat inferior.
Test No. No. 22 had a film thickness far exceeding 15 μm and was inferior in heat dissipation.
Test No. In No. 23, since the film was colorless, the integrated emissivity in the infrared region of the film was less than 0.80, and the heat dissipation was inferior.
Test No. 24, since the film is white, the integral emissivity in the infrared region of the film is less than 0.80, and the film is made of a polyester resin alone, and the heat resistance of the film is inferior. The film has melted.

  In addition, the LED heat sinks described in Patent Documents 1 to 4 are inventions in which shapes having fins are essential or recommended, and in order to realize these shapes with aluminum, there is no choice but to do it by die casting, It corresponds to a benchmark heat sink in the present invention. The casting alloy used in the die-casting method basically has a low thermal conductivity and it is difficult to reduce the weight. In addition, none of the heat sinks describes the surface that characterizes the present invention. As shown in the present embodiment, this conventional aluminum sheet does not satisfy a certain level in the above evaluation. Therefore, this example objectively revealed that the aluminum plate according to the present invention is superior to the conventional aluminum plate.

  Although the present invention has been described in detail with reference to the embodiments and examples, the gist of the present invention is not limited to the above-described contents, and the scope of the right is interpreted based on the description of the claims. There must be. Needless to say, the contents of the present invention can be modified and changed based on the above description.

DESCRIPTION OF SYMBOLS 1 Heat sink for vehicle-mounted LED lighting 2 Heat sink molded object 3 Film | membrane 3A Resin-type film | membrane 4 LED element 10 Precoat aluminum plate material 20 Aluminum plate material 100 Vehicle-mounted LED illumination

Claims (4)

Used as a heat sink for in-vehicle LED lighting, a pre-coated aluminum plate material having an aluminum plate material and a resin film,
The aluminum plate has a thermal conductivity of 150 W / m · K or more,
The resin-based film includes a thermosetting resin, a black pigment component, and an aggregate.
The film thickness of the resin-based film is 5 to 15 μm,
The arithmetic average roughness Ra of the surface of the resin film is 1 to 3 μm,
The precoat aluminum plate material, wherein the resin-based film has an integrated emissivity in an infrared region having a wavelength of 3 to 30 μm of 0.80 or more at 25 ° C.   The precoated aluminum sheet material according to claim 1, wherein the crystal structure of the aluminum sheet material is a fiber shape. A heat sink molded body formed of an aluminum wrought material, and a black film formed on the surface of the heat sink molded body, an automotive LED lighting heat sink comprising:
The thermal conductivity of the aluminum wrought material is 150 W / m · K or more,
The film thickness is 5-15 μm,
The arithmetic average roughness Ra of the surface of the film is 0.5 to 3 μm,
The heat sink for vehicle-mounted LED illumination, wherein the coating has an integrated emissivity in an infrared region having a wavelength of 3 to 30 μm of 0.80 or more at 25 ° C. The coating is a resin-based coating containing a thermosetting resin, a black pigment component, and an aggregate,
The heat sink for vehicle-mounted LED illumination according to claim 3, wherein the arithmetic average roughness Ra of the surface of the coating is 1 to 3 µm.

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