JP3476115B2 - Aluminum or aluminum alloy plate for disk shutter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum or aluminum alloy plate for a disk shutter, which is a material for a disk shutter provided in a case of a magnetic disk such as a flexible (floppy) disk and an optical disk such as an MO disk and a mini disk. Particularly, the present invention relates to an aluminum or aluminum alloy plate for a disk shutter, which is excellent in scratch resistance and bending workability.

[0002]

2. Description of the Related Art Magnetic disks such as flexible disks and optical disks such as MO disks and mini disks have a magnetic disk medium or an optical disk medium housed in a case. A magnetic head or an optical head is inserted in this case. An opening is provided as a window for reading / writing the magnetic disk medium or the optical disk medium. The case is provided with a disk shutter for opening and closing the opening.

FIG. 3 is a front view showing a floppy disk (hereinafter referred to as FD) 1 in which a recording magnetic disk medium 2 is housed. In the FD 1, the magnetic disk medium 2 is housed between the housing cases 3, and a window (not shown) for inserting a magnetic head is provided at the center of one side thereof. A shutter 4 for opening and closing is provided in this window.

The disc shutter 4 is a plate member having a U-shaped cross section, and is mounted on the storage case 3 so as to sandwich the case 3 between a pair of opposing surfaces. This shutter 4 is case 3
The window portion of the case 3 is opened and closed by sliding while being guided by the guide groove provided in the. Conventionally, the plate material for the disc shutter is made of stainless steel and synthetic resins such as polystyrene and ABS.

The function required of the disk shutter 4 is to open and close the magnetic disk medium 2 by a magnetic head when necessary and to protect the magnetic surface. Further, since the disc shutter 4 is guided and slidably moved on the case 3, it must be lightweight and rigid.

In order to reduce the weight, a plate material for disc shutters made of aluminum has been conventionally proposed. Also,
Since the disc shutter 4 is a sliding member, when the case 3 is damaged by the opening / closing operation, harmful shavings are generated on the disc 2. Therefore, in order to prevent the generation of the shavings, a disk shutter coated with a synthetic resin has been proposed (Japanese Patent Application Laid-Open No. 3-73479).
JP-A-6-346178). Further, a disk shutter in which a surface-hardened coating is provided on the surface of an aluminum alloy material to improve wear resistance and prevent plastic deformation is also known (Japanese Patent Laid-Open No. 6-68638). Further, there has been proposed a disk shutter provided with an anodized film on its surface for coloring (JP-A-6-111516 and JP-A-6-162710).

[0007]

However, these conventional disc shutters 4 have the following problems. First, the disk shutter made of stainless steel has a drawback that it is heavy, and further has a drawback that when the surface is touched with a hand, fingerprints are apt to be attached and the appearance is impaired.

Further, those made of synthetic resins such as polystyrene and ABS have a drawback that they are easily charged, and dust and dust are likely to adhere to them, which is harmful to the magnetic surface.

Further, the disc shutter 4 is printed with the manufacturer's name, product type, etc. on its surface by the UV curing method and displayed, but the synthetic resin disc shutter has a drawback that UV ink is hard to adhere thereto. In order to improve the adhesion of the UV ink, it is necessary to subject the synthetic resin disk shutter to a surface modification treatment such as corona discharge as a pretreatment. Therefore, there is a problem that the manufacturing cost becomes high.

Furthermore, the conventional disk shutter, which is made by coating only the synthetic resin on the surface of the aluminum alloy plate, has low lubricity and the film is soft, so that the surface is easily scratched and dust that is harmful to the magnetic surface is generated. Besides, the appearance of the disc shutter is significantly impaired due to the occurrence of flaws.

A conventional disk shutter in which the surface of an aluminum alloy plate is coated only with a synthetic resin is bent by 90 ° to have a U-shape.
At the 90 ° bent portion on the inner surface thereof, if the coating film is cracked and the coating film is peeled off, dust that is harmful to the magnetic surface comes out.

Further, when the disk shutter having the surface of the aluminum alloy plate anodized is bent at 90 ° to have a U-shape, cracks are formed in the film at the 90 ° bent portion on the inner surface thereof. The peeling of the coating makes it easier to generate dust that is harmful to the magnetic surface. Furthermore,
The anodized disk shutter is liable to have interference colors on its surface and is inferior in appearance. Furthermore, the anodizing treatment requires a stable current supply and a sufficient treatment time, which causes a problem of high manufacturing cost.

The present invention has been made in view of the above problems, and is lightweight, is less likely to be charged, prevents dust and dust from adhering, is less likely to be scratched on the surface, and is bendable. It is an object of the present invention to provide an aluminum or aluminum alloy plate for a disk shutter, which is excellent in UV ink printability.

[0014]

The aluminum or aluminum alloy plate for a disk shutter according to the present invention is used in a U-shaped cross-section shutter for opening and closing a window for a recording head provided in a case for accommodating a recording disk. In an aluminum or aluminum alloy plate for a disk shutter, a chromate film first layer formed on the surface of the aluminum or aluminum alloy plate on the outer surface side of the shutter, and a particle size of 0.5 to 10 μm formed on the first layer A wax-dispersed resin film second layer having a pencil hardness of 5H or more, a chromate film third layer formed on the surface of an aluminum or aluminum alloy plate on the inner surface of the shutter, and a pencil hardness formed on the third layer. It is characterized by having a resin coating fourth layer of 3H to 5H.

In this case, the second layer of the resin film preferably has a film thickness of 0.5 to 20 μm. The fourth layer of the resin film preferably has a film thickness of 1 μm or less. Further, the amount of the wax dispersed in the second layer of the resin film is preferably 0.5 to 10% by weight based on the weight of the film, and the kind thereof is polymer PE wax and PTEF.
It is preferably one type of spherical dispersion wax selected from the group consisting of waxes and fluorine-based waxes. Furthermore, the chromate film first layer and the chromate film third layer are formed by coating-type chromate treatment or phosphoric acid chromate treatment, and the adhesion amount is 5 to 30 in terms of Cr amount.
It is preferably mg / m ² .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
Description will be given with reference to the accompanying drawings. FIG. 1 is a perspective view showing a disc shutter 5 using an aluminum or aluminum alloy plate according to an embodiment of the present invention, and FIG. 2 is a transverse sectional view thereof. The shutter 5 is for the FD shown in FIG. As shown in FIGS. 1 and 2, the shutter 5 is formed by bending an aluminum or aluminum alloy plate at 90 ° on two sides to have a U-shaped cross section. The shutter 5 is provided with an opening 5c for inserting a magnetic head. When the shutter 5 slides and the opening 5c is aligned with the window provided in the case, the internal magnetic disk medium is exposed. ing.

In the aluminum or aluminum alloy plate of this embodiment, the chromate film is formed as the first layer on the surface which becomes the outer surface 5a of the shutter 5, and the grain is formed as the second layer on the chromate film. Diameter 0.5 to 10 μm
A resin film having a pencil hardness of 5H or more in which the above wax is dispersed is formed.

As described above, since the resin film having a pencil hardness of 5H or more is provided as the second layer, the surface hardness is high,
Moreover, since the wax having a particle diameter of 0.5 to 10 μm is dispersed in the second layer, the lubricity is high and the scratches are less likely to occur, so that the appearance of the disc shutter is excellent. Further, since the chromate film is provided as the first layer, the adhesion between the resin film of the second layer and the aluminum or aluminum alloy plate which is the base material is excellent, and dust that is harmful to the magnetic surface during the use process Hard to come out.

By setting the particle size of the wax dispersed in the second layer to 0.5 to 10 μm, a high lubricity is obtained and the adhesion of the UV ink printed by the UV curing method is also improved. improves. Since this wax is dispersed in the form of particles on the surface of the film, for example, when the aluminum or aluminum alloy plate of this embodiment comes into contact with a hard foreign material such as a working die, the wax particles cause the second layer of the resin film to contact. Direct contact between the matrix resin and the aluminum or aluminum alloy plate that is the base material of the matrix and hard foreign matter such as a working die is avoided, and the lubricating effect of the wax itself prevents the occurrence of defects. . However, if the particle size of the wax is less than 0.5 μm, the resin component of the coating and the aluminum or aluminum alloy plate are likely to come into contact with hard foreign matter, and the effect of preventing flaws is impaired. on the other hand,
The UV ink adheres to the surface of the resin film by the chemical bond with the resin component serving as the substrate of the resin film. However, when the particle size of the wax exceeds 10 μm, the chemical bond is blocked by the wax, and thus UV Ink adhesion decreases. Therefore, the particle size of wax is 0.5 to 10 μm.
To

Furthermore, if the pencil hardness of the surface of the resin coating of the second layer is less than 5H, the surface of the resin coating of the second layer is soft and hard foreign matter even if the effect of the above wax is appropriate. When it comes into contact, it becomes easier to get scratches. Therefore, the pencil hardness of the surface of the resin film formed as the second layer is 5H or more.

On the surface of the aluminum or aluminum alloy plate which becomes the inner surface 5b of the disk shutter 5, a third
A chromate film is formed as a layer, and a resin film having a pencil hardness of 3H to 5H is formed as a fourth layer. The fourth layer resin film has a pencil hardness of 3H to 5H, which is lower than that of the second layer and has appropriate flexibility. Therefore, when 90 ° bending processing is performed, the resin film is formed at the 90 ° bending portion 5d on the inner surface thereof. Follows the processing deformation of aluminum or aluminum alloy plate, and it is difficult for cracks and wrinkles to enter the coating. In addition, since the chromate film is provided as the third layer, the adhesion between the resin film of the fourth layer and the aluminum or aluminum alloy plate is excellent, and dust that is harmful to the magnetic surface is unlikely to appear.
However, when the pencil hardness of the resin film is higher than 5H, the flexibility of the film is lost, and when the 90 ° bending process is performed, the resin film cannot follow the processing deformation, and the 90 ° bending part 5 on the inner surface
At d, the coating is likely to be cracked and wrinkled.
Then, the peeling of the film facilitates the generation of dust that is harmful to the magnetic surface. On the other hand, when the pencil hardness of the resin film is lower than 3H, bending workability is not adversely affected, but the surface hardness of the film is low. Therefore, when the magnetic recording disk is used, the disk shutter 5 and the synthetic resin storage case 3 are used.
Due to the sliding of the disk shutter, the inner surface 5b of the disk shutter 5 is easily scratched, and dust that is harmful to the magnetic surface is easily generated. Therefore, the pencil hardness of the resin film formed as the fourth layer is set to 3 to 5H.

Next, the thicknesses of the second and fourth resin coating layers will be described. The film thickness of the second layer resin film, which is the outer surface 5a of the disk shutter 5, is preferably 0.5 to 20 μm. When the film thickness is less than 0.5 μm, the wax is less likely to be fixed in the film, and when it comes into contact with a hard foreign substance, the aluminum or aluminum alloy as the base material is likely to come into direct contact with the foreign substance, resulting in flaws. Easy to enter. On the other hand, when the film thickness is thicker than 20 μm, the manufacturing cost increases, and the abrasion powder of aluminum or aluminum alloy generated during the punching press working and the coating resin component are mixed into the working press oil, and the working press oil becomes sludge-like. , Clog the mold clearance.
In addition, it becomes difficult for the particulate wax to be dispersed on the surface of the film, and defects easily occur. Therefore, the film thickness of the resin film formed as the second layer is preferably 0.5 to 20 μm.

Further, the film thickness of the resin film formed as the fourth layer on the surface of the aluminum or aluminum alloy plate which becomes the inner surface 5b of the disk shutter 5 is preferably 1 μm or less. However, if the film thickness is more than 1 μm, the manufacturing cost becomes high, and the 90 ° bending process easily causes wrinkles in the film at the 90 ° bent portion 5d on the inner surface. Garbage is generated. Therefore, the film thickness of the resin film formed as the fourth layer is preferably 1 μm or less.

Further, the amount of wax dispersed in the second layer resin coating is preferably 0.5 to 10% by weight based on the weight of the coating. By dispersing the wax in the resin film, the lubricity of the film surface is improved, and the scratches are less likely to occur. However, if the amount of the wax is less than 0.5%, the effect of improving the lubricity becomes insufficient, and the flaws easily occur. On the other hand, wax deteriorates the wettability of the resin film surface, so if the amount of wax exceeds 10%, UV
Ink adhesion deteriorates. Therefore, the amount of wax is preferably 0.5 to 10% by weight based on the weight of the film.

The type of wax to be dispersed in the second layer resin film is preferably one selected from the group of spherical dispersion type wax consisting of polymer PE wax, PTEF wax or fluorine-based wax. Polymer PE
The wax has a high lubricity due to its linear molecule blending, and the PTEF wax and the fluorine-based wax have a high lubricity due to the high polarity of the fluorine contained in the wax, so that the flaw is less likely to enter. Further, since the shape of the dispersion type wax is spherical, the lubricity is improved due to the shape effect, and it becomes difficult for flaws to enter. On the other hand, animal fats and oils waxes such as lanolin and ordinary paraffin waxes are difficult to disperse in a spherical shape and are inferior to the above waxes in terms of molecular blending and polarity, so that lubricity is inferior and flaws are likely to occur. Therefore, it is preferable that the type of wax is one selected from the group of spherical dispersion type wax consisting of high molecular weight PE wax, PTEF wax or fluorine type wax.

The first layer chromate film on the outer surface 5a side and the third layer chromate film on the inner surface 5b side of the disk shutter 5 have a thickness (adhesion amount) of 5 to 30 mg / Cr in terms of Cr amount.
It is preferably m ² . Chromate film thickness is C
If the amount of r is less than 5 mg / m ² , the chromate film on the aluminum or aluminum alloy plate will be non-uniform and the adhesion with the resin film formed as the second and fourth layers will be insufficient, so the film Are easily peeled off. On the other hand, the amount of chromate film deposited is 30 mg / m ^{2 in} terms of Cr amount.
If the amount is more than 90%, the 90 ° bending process tends to cause cracks in the chromate film itself, and harmful dust is generated on the magnetic surface. Therefore, it is preferable that the chromate film has a Cr amount of 5 to 30 mg / m ² .

[0027]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. As a material, a plate material of aluminum alloy 5182-H38 (plate thickness 0.185 mm) was used. This aluminum alloy plate was alkali-degreased, washed with water and dried, and then subjected to phosphoric acid chromate treatment or coating type chromate treatment on both surfaces thereof to form a chromate film. Thereafter, a resin having a predetermined film composition of the second and fourth resin films was applied and then dried to form a resin film.

With respect to the various aluminum alloy plates for disc shutters produced in this manner, the film thickness (Cr amount) of the first and third layers of the chromate film and the second and fourth layers of the resin film were obtained. The surface hardness and film thickness, and the dynamic friction coefficient of the surface of the second layer of the resin film were measured, and the second
The scratch resistance of the layer and the fourth layer, the bending workability of the fourth layer, and the adhesion of the UV ink of the second layer were evaluated. The measurement methods and evaluation methods for these are shown below.

The film hardness was determined by the pencil hardness test of JIS K5400. The coefficient of kinetic friction was measured by using a 3/16 inch steel ball with a Bowden adhesion slip tester and sliding under the conditions of a load of 1000 gf and a sliding speed of 4 mm / sec.

Further, the scratch resistance of the aluminum alloy plate on the outer surface of the disk shutter was determined by observing the appearance of the sliding portion of the test plate used in the test for determining the dynamic friction coefficient. The evaluation criteria were as follows: ○ No scratches were found on the coating surface, △ was partially scratched, △ was that the aluminum alloy material as the base material had scratches.
Indicated as. The scratch resistance of the aluminum alloy plate on the inner surface of the disk shutter is the same test as the method of measuring the above-mentioned friction coefficient, but only the load is 200 gf, and then the appearance of the sliding portion of the test plate is observed. I asked for it. The evaluation standard is the same as the evaluation of the scratch resistance of the aluminum alloy plate on the outer surface of the disk shutter.

Furthermore, the bending workability was determined by subjecting the material to be tested to 90 ° bending under the condition of an inner diameter of 0 mm and observing the appearance of the 90 ° bending portion to find no cracks or wrinkles in the coating. ○, when fine cracks or wrinkles were generated in the coating but peeling of the coating was not observed △, cracks or wrinkles were generated in the coating and fine powder which was harmful dust on the magnetic surface due to peeling of the coating When the occurrence was confirmed, it was shown as x.

Further, the adhesion of the UV ink is determined by the UV ink (RIG BLACK No. 1) on the surface of the material tested.
No. 0; manufactured by Seiko Advance Co., Ltd. Two
After screen printing using 70 silk screen, 1 in UV irradiator (made by Eye Graphic Co., Ltd.)
It was cured by UV curing under the condition of 20 W / cm ² × 5 seconds, a cross cut was put in the printed part, and a peeling test was performed on the part with cellophane tape, and then the peeled state of the ink in the printed part was observed to investigate. As the evaluation of the result, ○ indicates that there was no ink peeling at all, Δ indicates that the ink peeling around the crosscut was 1 mm or less from the crosscut portion, and peeling reached a position longer than 1 mm from the crosscut portion. What was done was shown as x.

The composition and film thickness of the chromate film in each of the examples and comparative examples are the same on both front and back surfaces (first layer and third layer) of the aluminum alloy plate and are as shown in Table 1 below. Also, the composition of the second resin film on the outer surface side, the pencil hardness,
The wax composition, wax particle size, wax amount and film thickness are shown in Table 2 below. Further, Table 3 below shows the composition, pencil hardness, and film thickness of the fourth layer of the resin film on the inner surface side. Furthermore, Table 4 below shows the values of the respective properties and the evaluation results obtained for each of the examples and comparative examples.

[0034]

[Table 1]

[0035]

[0036]

[0037]

[Table 2]

[0038]

[0039]

[0040]

[Table 3]

[0041]

[0042]

[0043]

[Table 4]

[0044]

[0045]

As is clear from Tables 1 to 3, in Examples 1 to 22 of the present invention, the chromate film was formed on the outer surface of the disk shutter of the aluminum alloy plate, and the grain size was 0.5 to 0.5 on the chromate film. A resin film having a pencil hardness of 5H or more in which a 10 μm wax is dispersed is formed, a chromate film is formed on the inner surface of the disc shutter, and a resin film having a pencil hardness of 3 to 5H is formed on the chromate film. Is. As is clear from Table 4, these Examples 1 to 22 had high coating surface hardness, excellent lubricity, and were difficult to be flawed. Also,
Excellent results were also obtained in bending workability and UV ink adhesion.

Particularly, in Examples 1 to 17, the composition of the chromate film on the outer surface of the disk shutter, the film thickness and the amount of Cr, the amount of wax dispersed in the bark film, and the type of wax, as well as the composition of the chromate film on the inner surface of the disk shutter were used. Since the Cr content and the Cr content and the thickness of the bark coating were within the preferred ranges of the present invention, all the evaluation results were more excellent than those of Examples 18 to 22.

On the other hand, in Comparative Example 1, Comparative Example 2 and Comparative Example 4, the pencil hardness of the resin coating on the outer surface of the disk shutter was less than 5H, so the coating surface hardness was soft and easily scratched.
In Comparative Example 3, since neither the outer surface of the disk shutter nor the inner surface of the disk shutter was coated with a chromate film, the adhesion between the aluminum alloy plate as the base material and the resin film was insufficient, and it was easy to get a flaw and bent 90 °. Fine powder was generated due to the peeling of the film at the part, and harmful dust adhered to the magnetic surface. In Comparative Example 5, Comparative Example 10 and Comparative Example 11, since the particle size of the wax dispersed in the resin film on the outer surface 5a of the disk shutter 5 was less than 0.5 μm, sufficient lubricity could not be obtained, and scratches were prevented. The effect was also reduced, and the result was easily damaged. In Comparative Example 9, Comparative Example 12, and Comparative Example 13, the resin film on the outer surface of the disk shutter did not contain wax, and thus the lubricity was poor. Also,
Since the effect of preventing the scratches from wax was not obtained,
The result was easy to get scratched.

In Comparative Example 6, the particle size of the wax dispersed in the resin film on the outer surface of the disk shutter is as large as 20 μm, which exceeds the proper range of 10 μm, so that the adhesion of the UV ink is insufficient and the printing of the UV ink is defective. Occurred. In Comparative Example 7, since the pencil hardness of the resin coating on the inner surface of the disk shutter was less than 3H, a flaw was likely to occur due to the sliding of the disk shutter and the storage case, and harmful dust was likely to be attached to the magnetic surface. In Comparative Example 8, the pencil hardness of the resin film on the inner surface of the disk shutter exceeded 5H,
The coating is not flexible, and when subjected to 90 ° bending processing, the coating cannot follow the processing deformation of the aluminum alloy that is the base material, cracks or wrinkles occur, and the coating peels off at that portion, and the magnetic surface Hazardous garbage was generated.

On the other hand, since Comparative Example 14 was an anodized coating, the coating was cracked and peeled off inside the bend during 90 ° bending, and harmful dust was produced on the magnetic surface. Comparative Example 15 is a non-treated material, and it is easy to get scratches,
Further, the adhesion of UV ink was also poor.

[0051]

As described above, according to the aluminum or aluminum alloy plate for a disk shutter of the present invention, a chromate film of the first layer and a suitable chromate film are formed on the surface of the aluminum or aluminum alloy plate on the outer surface of the shutter. with a particle size of wax is formed and the second layer resin film having a suitable surface hardness which is dispersed, and a third layer chromate film on the surface of the inner surface side, a suitable surface hardness 4 Since a layer resin film is formed, the surface hardness of the outer surface of the disk shutter is sufficiently high, the surface lubricity is excellent, and the scratch resistance is also excellent, which is harmful to the magnetic surface. Can be prevented from adhering. Further, since the film on the inner surface side of the disk shutter has flexibility and has an appropriate surface hardness, it is possible to prevent generation of fine powder due to cracking and peeling of the film at the 90 ° bending portion, and at the same time, it is possible to protect the disk shutter and the storage case. The occurrence of flaws due to sliding can be avoided. Then, by optimizing the particle size and amount of the wax dispersed in the film on the outer surface of the disk shutter, UV
Ink adhesion is improved and peeling of the printed portion can be prevented when the recording disc is used.

Particularly, a resin film having a predetermined film thickness, a wax dispersed in a predetermined amount and a wax of a predetermined type are defined in the second layer on the outer surface of the disc shutter, and a resin film having a predetermined film thickness is further formed on the fourth layer on the inner surface of the disc shutter. By prescribing the same amount of Cr in the outer surface first layer and the inner surface third layer of the disc shutter, the lubricity, the scratch resistance, the bending workability and the adhesion of the UV ink are further improved. Become.

[Brief description of drawings]

FIG. 1 is a perspective view showing a disc shutter using an aluminum or aluminum alloy plate according to an embodiment of the present invention.

FIG. 2 is a cross sectional view of the same.

FIG. 3 is a front view showing a floppy disk in which a recording magnetic disk medium according to an embodiment of the present invention is housed.

[Explanation of symbols]

1; Floppy disk 2; Recording magnetic disk medium 3; Case 4, 5: Disc shutter 5a; outer surface of disc shutter 5b; inner surface of disc shutter 5c; window 5d; 90 ° bend

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-221936 (JP, A) JP-A-6-346178 (JP, A) JP-A-7-166125 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G11B 23/033 601 C23C 28/04

Claims (6)

(57) [Claims] 1. An aluminum or aluminum alloy plate for a disk shutter used for a U-shaped cross-section shutter for opening and closing a window for a recording head provided in a case for accommodating a recording disk, the aluminum or aluminum alloy on the outer surface side of the shutter. A chromate film first layer formed on the surface of the plate, a resin film second layer having a pencil hardness of 5H or more in which a wax having a particle diameter of 0.5 to 10 μm is dispersed, which is formed on the first layer, and a shutter. A disc having a third chromate film layer formed on the surface of an aluminum or aluminum alloy plate on the inner surface side and a fourth resin film layer having a pencil hardness of 3H to 5H formed on the third layer. Aluminum or aluminum alloy plate for shutters. 2. The second layer of resin film is 0.5 to 20.
The aluminum or aluminum alloy plate for a disk shutter according to claim 1, having a film thickness of μm. 3. The aluminum or aluminum alloy plate for a disk shutter according to claim 1, wherein the resin coating fourth layer has a film thickness of 1 μm or less. 4. The amount of wax dispersed in the second layer of the resin coating is 0.5 to 10% by weight with respect to the weight of the coating, according to claim 1. Aluminum or aluminum alloy plate for disk shutter. 5. The type of wax dispersed in the second layer of the resin film is one selected from the group of spherical dispersion type waxes consisting of polymer PE wax, PTEF wax and fluorine type wax. Claims 1 to 4
The aluminum or aluminum alloy plate for a disk shutter according to any one of 1. 6. The chromate film first layer and the chromate film third layer are formed by coating type chromate treatment or phosphoric acid chromate treatment, and the adhesion amount thereof is 5 to 30 mg / m ² in terms of Cr amount. Claim 1 characterized by
6. The aluminum or aluminum alloy plate for a disk shutter according to any one of items 1 to 5.