JP2005074963A - Pre-coat aluminum alloy plate excellent in heat releasing, anti-injury ability and electrical conductivity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pre-coat aluminum alloy plate excellent in all of heat-releasing, anti-injury ability and electrical conductivity. <P>SOLUTION: The plate comprises a substrate plate 2 composed of an aluminum alloy plate and pre-coat layers 3 and 4 formed on one or both surfaces of the substrate plate 2. At least one pre-coat layer 3 comprises a multi-layered coating film having two-layer structure, which is formed by laminating an under coating layer 31 comprising a first base resin 310 containing titanium oxide 311 and carbon black 312 to an upper coating layer 32 comprising the second base resin 320 into which granular synthetic resin beads 321 are dispersed. Preferably, the multi-layered coating film 3 is formed only on one surface of the substrate plate 2, and an electrical conductive film having single layer structure which comprises the third base resin 40 containing an electrical conductive material 41 is formed on the other surface of the substrate plate 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a precoated aluminum alloy plate that is used for an electronic device such as a plasma display or a housing for home appliances and is suitable for radiating heat inside the housing.

With the digitization of electronic and electrical devices, semiconductors such as highly integrated LSIs have been built in, and the interior of the housing has been heated more than ever.
The means for locally dissipating the semiconductor by a heat sink with a fan has been conventionally used, but more recently, in order to efficiently dissipate the overall heat in the casing, the plate material that constitutes the casing There is a strong demand for providing a heat dissipation function in itself, and various ideas have been made to satisfy it.

  For example, as a well-developed plate material, a specific amount of carbon black and titania is contained in the coating film on the substrate surface and the thermal emissivity is 60% or more (Patent Document 1), and a two-layer coating film on the substrate surface A specific amount of carbon black, alumina, zirconia, titania, silica, and the like is contained in the inner layer of this material, and the heat emissivity is 70% or more and the heat ray transmittance of the outer layer is 20% or more (Patent Document 2), An aluminum plate provided with an organic resin coating containing organic resin fine particles on one side (Patent Document 3), and a metal layer and a resin layer joined together via a thermoplastic resin fiber structure (Patent Document 4) )and so on.

By the way, in the case of current electronic devices and the like, high performance is required not only for heat dissipation as described above, but also for conductivity and scratch resistance.
However, none of the conventional plate materials described above satisfy all of heat dissipation, conductivity, and scratch resistance.

JP 2002-226783 A JP 2002-228085 A JP 2002-149083 A JP 2000-286565 A

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a precoated aluminum alloy plate excellent in all of heat dissipation, scratch resistance and conductivity.

1st invention consists of the board | substrate which consists of an aluminum alloy plate, and the precoat layer formed in the single side | surface or both surfaces of this board | substrate,
At least one of the precoat layers includes an undercoat layer containing titanium oxide and carbon black in the first base resin;
Heat dissipation, scratch resistance, and a multilayer coating film having a two-layer structure by laminating an overcoat layer in which resin beads made of particulate synthetic resin are dispersed in a second base resin It exists in the precoat aluminum alloy plate excellent in electroconductivity (Claim 1).

  As described above, the precoated aluminum alloy plate of the present invention has a precoat layer on one side or both sides thereof. And when there is a precoat layer on one side, the precoat layer consists of the above-mentioned multi-layer coating film, and when both sides have a pre-coat layer, one or both pre-coat layers are composed of the above-mentioned multi-layer coating film. Yes. The multilayer coating film has a two-layer structure in which an undercoat layer and an overcoat layer having the above-mentioned specific structure are laminated. Therefore, the precoated aluminum alloy plate is excellent in heat dissipation, conductivity, and scratch resistance.

That is, the undercoat layer constituting the multilayer coating film is constituted by containing titanium oxide and carbon black in the first base resin as described above. Therefore, the functions of heat dissipation and conductivity can be added to the multilayer coating film by the heat dissipation and conductivity of the titanium oxide and carbon black.
Further, as described above, the overcoat layer constituting the multilayer coating film is constituted by dispersing resin beads made of particulate synthetic resin in the second base resin. Therefore, scratch resistance can be improved by the presence of the resin beads.
And by the two-layer structure of the undercoat layer and the overcoat layer, a precoat layer that can simultaneously exhibit a plurality of functions of heat dissipation, conductivity, and scratch resistance can be formed.

  In the present invention, the undercoat layer uses a polyester resin-based paint containing a polyester resin having a number average molecular weight of 5000 to 30000 as a main component as the first base resin, and is oxidized with respect to 100 parts by weight of the polyester resin. It is preferable that 3 to 60 parts by weight of titanium, 0.2 to 15 parts by weight of carbon black are contained, and the film thickness is 1 to 40 μm.

That is, it is preferable to use a polyester resin-based paint as described above as the first base resin and set the number average molecular weight to 5000 to 30000. More specifically, examples of the polyester resin-based paint include unsaturated polyester resins, fatty acid-modified polyester resins (alkyd resins), oil-free alkyd resins, and cotton-like polyester resins.
Further, when the number average molecular weight is less than 5000, there is a problem that the workability of the coating film is impaired. On the other hand, when it exceeds 30000, there is a problem that the scratch resistance of the coating film is impaired.

  Moreover, it is preferable that the titanium oxide contained in said 1st base resin shall be 3-60 weight part with respect to 100 weight part of polyester resins. When the amount is less than 3 parts by weight, there is a problem that the thermal radiation is lowered, while when it exceeds 60 parts by weight, there is a problem that the workability of the coating film is impaired.

  The carbon black contained in the first base resin is preferably 0.2 to 15 parts by weight with respect to 100 parts by weight of the polyester resin. If the amount is less than 0.2 parts by weight, there is a problem that the thermal radiation is reduced, while if it exceeds 10 parts by weight, the processability of the coating film is impaired.

  Furthermore, the thickness of the undercoat layer is preferably 1 to 40 μm. When the film thickness is less than 1 μm, there is a problem that the thermal radiation becomes insufficient. On the other hand, when it exceeds 40 μm, the workability of the coating film is impaired, and the effect of improving the thermal radiation is saturated. There's a problem.

  Next, the overcoat layer is made of a polyester resin-based paint containing a polyester resin having a number average molecular weight of 5000 to 30000 as a main component as the second base resin, and the resin having a particle diameter D of 3 to 90 μm. 1 to 200 parts by weight of beads with respect to 100 parts by weight of the polyester resin, the film thickness T of the part where the resin beads do not exist is 1 to 30 μm, and the particle diameter D / the film thickness T (hereinafter, D / T) is preferably in the range of 1 to 3 (claim 3).

  First, as the second base resin, it is preferable to use a polyester resin-based paint as described above and set the number average molecular weight to 5000 to 30000. Specific examples of the polyester resin-based paint include those similar to those described above, and the reason for limiting the number average molecular weight is also the same as described above.

  The resin beads contained in the second base resin preferably have a particle size D of 3 to 90 μm. When the particle size D is less than 3 μm, there is a problem that the effect of improving the scratch resistance due to the presence of the resin beads cannot be obtained sufficiently. On the other hand, when the particle size of the resin beads exceeds 90 μm, there is a problem that the resin beads easily fall off from the overcoat layer.

  The resin beads contained in the second base resin are preferably 1 to 200 parts by weight with respect to 100 parts by weight of the polyester resin. When this content is less than 1 part by weight, there is a problem that sufficient scratch resistance cannot be obtained, while when it exceeds 200 parts by weight, the ratio of the base resin to the resin beads is too small, There is a problem that coating film cracking is likely to occur during bending.

  Moreover, it is preferable that the film thickness T of the part in which the said resin bead does not exist of the said overcoat is 1-30 micrometers. When the film thickness T is less than 1 μm, there is a problem that the resin beads are likely to drop off. On the other hand, when the film thickness exceeds 30 μm, it is difficult to dry when baking the paint, and a sound coating cannot be formed, and this part is cracked during molding. Is likely to occur, and there is a problem that press formability is lowered.

  Further, the D / T is preferably in the range of 1 to 3. When the D / T is less than 1, sufficient scratch resistance cannot be obtained. On the other hand, when the D / T exceeds 3, there is a problem that the resin beads easily fall off from the overcoat layer.

Moreover, it is preferable that the said overcoat layer of the said multilayer coating film contains 0.05-3 weight part inner wax with respect to 100 weight part of said 1st base resins. In this case, due to the presence of the inner wax, the workability of the precoated aluminum alloy plate can be improved in each stage.
The content of the inner wax is preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the first base resin. When the content of the inner wax is less than 0.05% by weight, there is a problem that the slipperiness is deteriorated and the formability is lowered. On the other hand, when the content exceeds 3%, the precoated aluminum alloy plate is mass-produced. When the coil is raised in the manufacturing process, there is a problem that the inner wax oozes out and decreases productivity.
As the inner wax, for example, lanolin, carnauba, polyethylene or the like can be used.

Moreover, it is preferable that the chemical conversion treatment film is formed between the said multilayer coating film and the said board | substrate (Claim 5).
Examples of the chemical conversion treatment film include chromate treatment such as phosphate chromate and chromate chromate, chemical film treatment such as non-chromate treatment with titanium phosphate, zirconium phosphate, molybdenum phosphate, zinc phosphate, etc. other than chromium compounds, so-called A film obtained by chemical conversion treatment is employed.

The presence of this chemical conversion coating can effectively improve the adhesion between the substrate made of an aluminum alloy plate and the multilayer coating film. In addition, excellent corrosion resistance is realized, and corrosion under the coating caused when corrosive substances such as water and chlorine compounds permeate the surface of the aluminum alloy plate is suppressed, and prevention of coating cracking and peeling is prevented. Can be achieved.
The chemical conversion treatment methods such as chromate treatment and non-chromate treatment include a reaction type and a coating type, but any method may be adopted in the present invention.

Moreover, it is preferable that the said overcoat layer of the said multilayer coating film contains the pigment (Claim 6). In this case, by selecting the type of pigment to be included, various designs can be obtained, and the diversity of products that can be produced by the precoated aluminum alloy plate can be enhanced.
Examples of the pigment include ferric ferrocyanide, basic aluminum sulfate, silica, alumina, mica, barium sulfate, titanium oxide, iron oxide, carbon black, aluminum powder, bronze powder, complex oxide pigment, organic There are pigments.

  Further, the multilayer coating film is formed only on one surface of the substrate, and the other surface of the substrate has a single layer structure containing a conductive substance having electrical conductivity in the third base resin. It is preferable that a conductive coating film exhibiting the above is formed (Claim 7). In this case, the presence of the conductive coating can further increase the conductivity of the precoated aluminum alloy plate.

  In addition, the conductive coating film uses a polyester resin-based paint containing a polyester resin having a number average molecular weight of 5,000 to 30,000 as a main component as the third base resin, and the above-mentioned amount with respect to 100 parts by weight of the polyester resin. It is preferable that the conductive material is contained in an amount of 5 to 100 parts by weight and the film thickness is 5 to 20 μm.

  As the third base resin, it is preferable to use a polyester resin-based paint as described above and set the number average molecular weight to 5000 to 30000. Specific examples of the polyester resin-based paint include those similar to those described above, and the reason for limiting the number average molecular weight is also the same as described above.

  Moreover, it is preferable that content of the said electroconductive substance is 5-100 weight part with respect to 100 weight part of polyester resins. When the content of the conductive material is less than 5 parts by weight, there is a problem that the conductivity of the coating film becomes insufficient. On the other hand, when the content exceeds 100 parts by weight, the design property of the coating film is impaired. There's a problem.

  Moreover, it is preferable that the film thickness of the said conductive coating film is 5-20 micrometers. When the film thickness is less than 5 μm, there is a problem that heat dissipation and scratch resistance are impaired, while when it exceeds 20 μm, there is a problem that conductivity is impaired.

The conductive substance may be composed of a scale-like Ni filler having a thickness of 0.2 to 5 μm and a major axis of 2 to 50 μm, and / or a spherical Ni filler having a diameter of 0.3 to 20 μm. Preferred (claim 9).
As the conductive material, a material capable of imparting conductive performance to the precoat layer, for example, a known conductive material such as Ni-coated graphite, Ni, metal oxide, graphite, or carbon black can be applied. Of these, the scale-like Ni filler and the spherical Ni filler are particularly preferable.

The shape of the Ni filler may be a scaly shape, a spherical shape, or a mixture of both.
In the case of scales, the thickness is 0.2 to 5 μm and the major axis is 2 to 50 μm. When the thickness is less than 0.2 μm or the major axis is less than 2 μm, the conductivity is lowered and the slidability is also lowered. When the thickness exceeds 5 μm or the major axis exceeds 50 μm, the average roughness of the surface of the conductive layer becomes too rough, and in this case, the slidability decreases. More preferable sizes are 0.5 to 3 μm in thickness and 5 to 30 μm in major axis.
In the case of a spherical shape, the diameter is 0.3 to 20 μm. When it is less than 0.3 μm, the conductivity is lowered and the slidability is lowered. On the other hand, when it exceeds 20 μm, the average roughness of the surface of the conductive layer becomes too rough, and in this case, the slidability decreases. A more preferable diameter is 1 to 15 μm.

In addition, when mixing flaky Ni filler and spherical Ni filler, it is preferable that those weight ratios shall be set to flaky Ni filler amount / spherical Ni filler amount = 1 / 3-19 / 1. When it is less than / 3 or exceeds 19/1, the balance between the scale-like Ni filler and the spherical Ni filler is poor, and the conductivity tends to decrease.
In the case of a spherical Ni filler, it is more advantageous for the conductivity that each Ni filler is close to a true sphere and has a diameter of 1 to 5 times the base coating thickness. The true sphere here means that the maximum diameter / minimum diameter = 0.7-1.

  The content of the Ni filler is 3 to 70 parts by weight when the total weight of the top coat layer (the total weight including the second base coating film, the Ni filler, and the inner wax described later) is 100. preferable. In the case of a scaly and spherical mixture, the total amount of both is 3 to 70 parts by weight. When the amount is less than 3 parts by weight, the conductivity is lowered and the slidability is lowered. When it exceeds 70 parts by weight, the average roughness of the surface of the conductive layer becomes too rough, and in this case, the slidability is lowered.

Moreover, it is preferable that the said conductive coating film also contains 0.05-3 weight part inner wax with respect to 100 weight part of said 3rd base resin similarly to the case of the said multilayer coating film. (Claim 10).
Moreover, it is preferable that the chemical conversion treatment film is formed between the said conductive coating film and the said board | substrate like the said multilayer coating film and the said board | substrate (Claim 11).

(Example 1)
The precoated aluminum alloy plate according to the embodiment of the present invention will be described in more detail with reference to FIG.
In this example, as will be described later, a plurality of types of precoated aluminum alloy plates (A1 to A26, B1 to B26) were produced and their performance was evaluated.

As shown in FIG. 1, the precoated aluminum alloy plate 1 produced in this example includes a substrate 2 made of an aluminum alloy plate and precoat layers 3 and 4 formed on both surfaces of the substrate 2.
One precoat layer 3 includes an undercoat layer 31 containing titanium oxide 311 and carbon black 312 in the first base resin 310, and resin beads 321 made of particulate synthetic resin in the second base resin 320. It consists of the multilayer coating film which exhibits the two-layer structure which laminated | stacked the topcoat layer 32 which disperse | distributes.
The other precoat layer 4 is composed of a conductive coating film having a single layer structure in which a conductive material 41 having electrical conductivity is contained in the third base resin 40.
Hereinafter, this configuration will be described in more detail.

First, as a substrate 2 made of an aluminum alloy plate, a high-strength material (GC150) having chemical components shown in Table 1, a plate thickness of 1.0 mm, and a tempered O plate was used.
The substrate 2 was subjected to a degreasing treatment and then a base treatment for forming the chemical conversion films 51 and 52. Table 2 shows the four types of chemical conversion treatments (ad) adopted in this example.

In the chemical conversion treatment a, a reactive chromate film is formed by phosphoric acid chromate treatment so that the amount of chromium deposited is 20 mg / m ² . Specifically, the chemical conversion treatment was performed by immersing the sample in the chemical conversion treatment solution, washed with water, and dried in an atmosphere of about 100 ° C.
In the chemical conversion treatment b, a reactive non-chromate film is formed by reactive zirconium treatment so that the amount of zirconium deposited becomes 10 mg / m ² . Specifically, the chemical conversion treatment was performed by immersing the sample in the chemical conversion treatment solution, washed with water, and dried in an atmosphere of about 100 ° C.

In the chemical conversion treatment c, a coating-type chromate film is formed by coating-type chromate treatment so that the chromium adhesion amount is 20 mg / m ² . Specifically, the treatment agent was applied by a bar coating method and then dried in an atmosphere at about 100 ° C.
In the chemical conversion treatment d, a coating-type non-chromate film is formed by coating-type zirconium treatment so that the amount of zirconium deposited becomes 10 mg / m ² . Specifically, the treatment agent was applied by a bar coating method and then dried in an atmosphere at about 100 ° C.

As the first to third base resins 310, 320, and 40 of each layer constituting the precoat layers 3 and 4, as shown in Table 3, two types of polyester resins having different number average molecular weights manufactured by Toyobo Co., Ltd. (A and B) were prepared.
Further, as shown in Table 4, six types of resin beads 321 to be contained in the overcoat layer 32 were prepared.

  Further, the top coat layer 32 contained a color pigment 322 in addition to the resin beads 321. The color pigment contained in this example was a gray paint by blending 80 parts by weight of titanium oxide, 3 parts by weight of iron yellow, 1 part by weight of carbon black, and 1 part by weight of a petal with respect to 100 parts by weight of the polyester resin.

The titanium oxide and carbon black added to the undercoat layer 31 also functions as a pigment.
Further, as shown in Table 5, two kinds of shapes (I, II) were used as the conductive substance contained in the precoat layer 4 made of the conductive coating film. Type (I) is a spherical Ni filler having a minor axis / major axis ratio of less than 0.1, and type (II) is a flaky (scale-like) Ni filler having a minor axis / major axis ratio of about 0.7. It is.

  The topcoat layer 32 in the precoat layer 3 made of the multilayer coating film and the precoat layer 4 made of the conductive coating film both contained an inner wax. Polyethylene wax and carnauba wax were used as the inner wax.

The painting was performed as follows.
For each paint, a polyester resin, a melamine-based cross-linking agent (10 parts by weight with respect to 100 parts by weight of the polyester resin), various pigments, resin beads, conductive materials, and the like were sufficiently stirred with a mixer and subjected to the test. Each of these coating materials was applied to the substrate 2 made of an aluminum alloy subjected to the base treatment by a bar coating method, and baked at a temperature of 250 ° C. for 2 minutes to form a coating film.
The order of coating was performed in the order of the undercoat layer 31 in the precoat layer 3 on the surface, the conductive coating film 4 on the back surface, and finally the topcoat layer 32 on the surface. The dry coating thickness of each layer was such that the undercoat layer 31 and the topcoat layer 32 were 12 μm, and the conductive coating film 4 was 12 μm.

Next, the following three types of evaluation tests were performed.
<Heat dissipation>
The heat dissipation was performed by measuring the thermal emissivity. The thermal emissivity to be measured is an emissivity α calculated by the following formula (1) from the spectral reflectance of the surface in the wavelength range of 2.5 to 25 μm, and relative to the case of 293 K in Planck's thermal radiation spectrum distribution. The emissivity considering the value. In addition, the spectral reflectance for calculating | requiring this thermal emissivity was measured using the spectrophotometer. The thermal emissivity was measured from the surface of the topcoat layer 32 and the conductive coating film 4.
α = (1−∫G (λ) · R (λ) d (λ) × 100 (1)
However, G (λ) is a relative value in the case of 293K in the Planck's thermal radiation spectrum distribution, and R (λ) is a spectral reflectance.
The evaluation was made in three stages, 3 points when the thermal emissivity was 90% or more, 2 points when the thermal emissivity was 80% or more and less than 90%, and 1 point when the thermal emissivity was less than 80%. In this case, two or more points were accepted.

<Scratch resistance>
The scratch resistance was measured by a Bowden test. That is, a steel ball having a diameter of 0.25 inches with a load of 100 g was slid back and forth on the coating film surface of the sample placed on the sample table, and the number of evaluations until the coating film breakage was evaluated.
The evaluation was made in three stages: 3 points when the sliding number was 100 times or more, 2 points when the sliding number was 50 times or more, and 2 points when the sliding number was less than 50 times, and 1 point. In this case, two or more points were accepted.

<Conductivity>
The conductivity was evaluated by measuring a contact resistance value by a cylindrical electrode method. In the cylindrical electrode method, a cylindrical electrode having a diameter of 3 mm is placed on the back surface, and 100 g, which is a load that does not penetrate the conductive coating film 4, is applied. The value was measured with an electric resistance meter.
The evaluation was made in three stages, 3 points when the contact resistance value was less than 1Ω, 2 points when the contact resistance value was 1Ω or more and less than 3Ω, and 1 point when the contact resistance value was 3Ω or more. In this case, two or more points were accepted.

<Lubricity>
Lubricity was also measured by the Bowden test. That is, the friction coefficient was measured when the steel ball having a weight of 100 g and a diameter of 0.25 inch was reciprocated 100 times on the surface of the coating film of the sample placed on the sample table.
The evaluation was made in three stages, and the case where the friction coefficient was 0.05 or more and less than 0.1 was 3 points, the case where the friction coefficient was 0.1 or more and less than 0.3 was 2 points, and the case where it was 0.3 or more was 1 point. In this case, two or more points were accepted.

  The evaluation results are shown in Tables 6-9.

  As can be seen from Tables 6 and 7, Samples A1 to A16 have all the requirements in the multilayer coating film 3 on the surface within the scope of the present invention, and show excellent characteristics in all evaluation items. It was. On the other hand, samples A17 to A26 were inferior to the product of the present invention in at least one evaluation item, as any of the elements constituting the multilayer coating film 3 deviated from the scope of the present invention.

  Similarly, as is known from Tables 8 and 9, in Samples B1 to B16, all the requirements in the conductive film 4 on the back are all within the scope of the present invention, and excellent in all evaluation items. The characteristics are shown. On the other hand, Samples B17 to B26 are inferior to the product of the present invention in at least one evaluation item because any of the elements constituting the conductive coating film 4 is out of the scope of the present invention.

Explanatory drawing which shows the structure of the precoat aluminum alloy plate in an Example.

Explanation of symbols

1 Pre-coated aluminum alloy plate 2 Substrate 3 Pre-coated layer (multi-layer coating film)
31 Undercoat layer 310 First base paint 311 Titanium oxide 312 Carbon black 32 Overcoat layer 320 Second base paint 321 Resin beads 322 Pigment 4 Precoat layer (conductive coating film)
40 Third base paint 41 Conductive material 51, 52 Chemical conversion coating

Claims (11)

It consists of a substrate made of an aluminum alloy plate and a precoat layer formed on one or both sides of the substrate,
At least one of the precoat layers includes an undercoat layer containing titanium oxide and carbon black in the first base resin;
Heat dissipation, scratch resistance, and conductivity characterized by comprising a multi-layer coating film having a two-layer structure in which a resin layer made of particulate synthetic resin is dispersed in a second base resin and an overcoat layer. Precoated aluminum alloy plate with excellent properties.   2. The undercoat layer according to claim 1, wherein the first base resin is a polyester resin-based paint containing a polyester resin having a number average molecular weight of 5000 to 30000 as a main component, and is based on 100 parts by weight of the polyester resin. Precoat excellent in heat dissipation, scratch resistance and conductivity, containing 3 to 60 parts by weight of titanium oxide, 0.2 to 15 parts by weight of carbon black, and having a film thickness of 1 to 40 μm Aluminum alloy plate.   3. The overcoat layer according to claim 1, wherein the overcoat layer comprises a polyester resin-based paint containing, as a main component, a polyester resin having a number average molecular weight of 5000 to 30000 as the second base resin, and the particle size D is 3 to 3. The resin beads of 90 μm are contained in an amount of 1 to 200 parts by weight with respect to 100 parts by weight of the polyester resin, the film thickness T of the part where the resin beads are not present is 1 to 30 μm, and the particle diameter D / the film thickness A precoated aluminum alloy plate excellent in heat dissipation, scratch resistance and conductivity, wherein T is in the range of 1 to 3.   In any 1 item | term of Claims 1-3, the said top coat layer of the said multilayer coating film contains 0.05-3 weight part inner wax with respect to 100 weight part of said 1st base resins. A precoated aluminum alloy plate excellent in heat dissipation, scratch resistance and conductivity.   In any one of Claims 1-4, it is excellent in heat dissipation, scratch resistance, and electroconductivity characterized by the chemical conversion treatment film being formed between the said multilayer coating film and the said board | substrate. Pre-coated aluminum alloy plate.   6. The precoated aluminum alloy plate according to claim 1, wherein the overcoat layer of the multilayer coating film contains a pigment, and is excellent in heat dissipation, scratch resistance, and conductivity. .   7. The multilayer coating film according to claim 1, wherein the multilayer coating film is formed only on one surface of the substrate, and the other surface of the substrate is electrically conductive in a third base resin. A precoated aluminum alloy plate excellent in heat dissipation, scratch resistance and conductivity, characterized in that a conductive coating film having a single layer structure containing a conductive substance having a thermal conductivity is formed.   8. The conductive coating film according to claim 7, wherein the conductive coating film comprises a polyester resin-based paint containing a polyester resin having a number average molecular weight of 5000 to 30000 as a main component as the third base resin. On the other hand, a precoated aluminum alloy plate excellent in heat dissipation, scratch resistance and conductivity, containing 5 to 100 parts by weight of the conductive material and having a film thickness of 5 to 20 μm.   9. The conductive material according to claim 7, wherein the conductive substance is a flaky Ni filler having a thickness of 0.2 to 5 μm and a major axis of 2 to 50 μm, and / or a spherical Ni having a diameter of 0.3 to 20 μm. A precoated aluminum alloy plate excellent in heat dissipation, scratch resistance and conductivity, characterized by comprising a filler.   The conductive film according to any one of claims 7 to 9, wherein the conductive coating contains 0.05 to 3 parts by weight of an inner wax with respect to 100 parts by weight of the third base resin. Precoated aluminum alloy plate with excellent heat dissipation, scratch resistance and conductivity.   In any one of Claims 7-10, it is excellent in the heat dissipation, scratch resistance, and electroconductivity characterized by the chemical conversion treatment film being formed between the said electroconductive coating film and the said board | substrate. Pre-coated aluminum alloy plate.

Images