JP2001184845A - Coating film coated aluminum alloy material for recording medium drive case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin coated aluminum alloy material for a recording medium drive case which has high strength and excellent slidability, fingerprint resistance and corrosion resistance, has the excellent conductive of a surface and allows easy grounding. SOLUTION: The resin coated aluminum alloy material for a recording medium drive case chassis is formed by forming a coating film consisting of a silicate compound, an organic resin, a silane coupling agent and a solid lubricant on the surface of an aluminum alloy sheet containing 2.0 to 6.0 mass% Mg. The coating film is 20 to 1,000 mg/m2 in coating film weight in terms of Si, has pores of <=1 μm in average diameter on its surface and the surface resistance value thereof is <=20 θ. The resin coated aluminum alloy material has tension characteristics of 210 to 410 MPa in tensile strength and 150 to 370 MPa in bearing strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a personal computer (PC) and other computer-related equipment.
-ROM (compact disc-read only memory), DVD
The present invention relates to a coated aluminum alloy material for a recording medium drive case suitable for a drive case in a drive device for operating a recording medium such as a (digital video disk), a magneto-optical disk, and a micro floppy disk. In the present invention, the drive case also includes a chassis for fixing the drive case to the main body of the personal computer.

[0002]

2. Description of the Related Art CD-ROs are used in word processors, personal computers and other computer-related equipment.
Drive devices for operating recording media such as M, DVD, magneto-optical disk, optical disk, and micro floppy disk include devices for reading information from a recording medium, writing information on a recording medium, and devices for driving a recording medium. In order to protect these device components and the recording medium itself, these device components are housed in a case having an upper lid and a lower lid member.

[0003] Since these drive cases are installed near a CRT (cathode ray tube) in a word processor, personal computer and other computer-related equipment, electromagnetic noise generated from the CRT and minute current generated when the equipment is driven. In some cases, problems such as insufficient reading of information from a recording medium contained in the drive device and defective writing to the recording medium may occur. Therefore, it is necessary to prevent the flow of minute current into the drive device by grounding the drive device in order not to cause any trouble to the memory of these recording media.

[0004] As for the method of grounding, a method of connecting a ground wire directly in the drive device and a member having excellent conductivity such as a leaf spring made of stainless steel (SUS) are brought into contact with the surface of the drive case. And other methods have been implemented. In addition, in order to take the ground from the drive case, the surface and the end face of the material forming the drive case need to have conductivity.

[0005] Further, since the recording medium generates heat during operation, it is necessary to release the heat through the drive case. Therefore, the drive case is formed of a material such as metal which is excellent in heat transfer. There is a need.

Further, since these drive devices are configured to be attached to and detached from word processors, personal computers and other computer-related devices, they are frequently attached and detached. In such a case, since the drive case is directly touched with bare hands, fingerprints adhere to the case. Thus, if the fingerprint attached to the case is conspicuous, the appearance of the case is impaired. In addition, when the drive case comes into contact with the surroundings when removing the drive device, or comes into contact with parts for fixing the drive device when attaching the drive device to a word processor, a personal computer and other computer-related devices, the surface of the drive case may be damaged. Scratches and impair the appearance. Furthermore, during the forming of the drive case and the assembling of the drive device, there is a possibility that the surface may be scratched or a fingerprint may be attached, and this also impairs the appearance.

In recent years, portable devices such as notebook word processors, laptop and notebook personal computers and mobile devices have been developed.
A reduction in weight is required, and accordingly, a drive device mounted on these devices is also required to be reduced in weight.

Conventionally, the materials used for the cases of these drive devices are mainly SPCC (cold rolled steel sheet and steel strip), galvanized steel sheet and chromate steel sheet from the viewpoint of requiring conductivity. Steel sheets are used. However, when these steel sheets are used, their weight becomes heavy, and they are not suitable for weight reduction accompanying the portable computer equipment. In addition, these steel sheets are liable to cause scratches on the surface of the case when forming the drive case, assembling the drive device, and attaching / detaching the drive case to / from the device. There is a point.

[0009] From the viewpoint of reducing the weight of devices such as personal computers accompanying portability, there is a method in which untreated aluminum alloy plates are used for drive cases instead of steel plates. However, an untreated aluminum alloy plate has a problem that the surface is easily scratched, as in the case of the above-described steel plates. Also, although the fingerprint resistance is reduced as compared with steel plates, it is insufficient as a drive case material.

Further, an aluminum alloy plate which has been subjected to a phosphoric acid chromate treatment has been proposed, but like the untreated aluminum alloy plate, the surface is easily damaged and the fingerprint resistance is insufficient.

In order to solve the above-mentioned problems caused by surface flaws and the adhesion of fingerprints, Japanese Patent Application Laid-Open No. 4-330683 discloses a technique of coating a resin containing a lubricant on an aluminum alloy plate. (Conventional example 1).
According to this, one surface of an aluminum alloy plate is coated with an epoxy-based, acrylic-based, or PVC-based resin, and the resin coating film has a thickness of 0.5.
To 1.5 μm, containing 0.2 to 5% of a lubricant, and having a friction coefficient of 0.50 or less.

Further, Japanese Patent Application Laid-Open No. 6-346178 discloses an aluminum alloy material for a shutter of a sheet-shaped recording medium cassette which is lightweight, has sliding properties, fingerprint resistance and corrosion resistance (conventional example 2). . According to this, Mg:
3.0 to 6.0 mass%, the balance being Al and inevitable impurities, tensile strength: 310 to 410MP
a, yield strength: a synthetic resin-based coating film having a thickness of 20 μm or less is formed on the surface of an aluminum alloy plate having a strength of 250 to 370 MPa.

Further, as a conductive metal plate used for home electric appliances and the like that require a grounding property, a metal plate in which a coating containing a conductive substance is formed on an aluminum plate is disclosed. (See, for example, JP-A-5-57239, 5-32
0934, 7-290253, 7-313930 and 7
In these techniques, for example, a coating film is formed on the surface of an aluminum plate,
The thickness of the coating film is 0.5 to 3 μm,
The metal or metal oxide such as Ni is contained in an amount of 11 to 200 parts by mass with respect to 00 parts (conventional example 3).

Furthermore, JIS A 1100 alloy and the like are often used as aluminum materials used for parts of these computer-related devices because of their good workability (conventional example 4).

[0015]

However, in the technique of the prior art 1, when a resin coating film containing a lubricant is formed on the surface of the aluminum alloy plate, the surface becomes insulative. Similarly, in the technology of Conventional Example 2, desired conductivity cannot be obtained on the surface of an aluminum alloy plate having a synthetic resin-based coating film formed on the surface. There is a problem that it is difficult to take the ground.

Further, in the metal plate on which the film described in the conventional example 3 is formed, the resistance value of the material surface is not sufficiently low, and the material is formed into a drive case. Is inadequate. Furthermore, this alloy plate has a problem that the strength and workability required for the drive case cannot be obtained.

Further, the alloy of Conventional Example 4 has excellent formability for forming into a drive case, but has a low strength and is easily scratched on the surface, and is deformed during assembly and use (during attachment and detachment). There are problems such as occurrence.

The present invention has been made in view of the above problems, and has high strength, excellent sliding properties, fingerprint resistance and corrosion resistance, excellent surface conductivity, and easy grounding. It is an object of the present invention to provide an aluminum alloy material coated with a coating film for a drive case of a recording medium capable of performing the recording.

[0019]

According to the present invention, a coating-coated aluminum alloy material for a recording medium drive case according to the present invention comprises Mg:
An aluminum alloy plate containing 2.0 to 6.0% by mass, and a coating film composed of a silicate compound, an organic resin, a silane coupling agent and a solid lubricant on the surface thereof, wherein the coating film is The film amount is 20 to 1000 mg / m in terms of Si amount.
² , having pores with an average diameter of 1 μm or less on the surface, having a surface resistance of 20 Ω or less, an overall tensile strength of 210 to 410 MPa, and a proof stress of 150 to 370 M
Pa.

In the present invention, since the aluminum alloy plate contains 2.0 to 6.0% by mass of Mg, the strength is high, and the coating film formed on the surface is composed of a silicate compound, an organic resin, a silane compound. Since it is composed of a coupling agent and a solid lubricant, pores are formed on the surface, thereby having conductivity. Therefore, this coating-coated aluminum alloy material has excellent corrosion resistance, fingerprint resistance, slidability, and corrosion resistance, and also has high conductivity.

Further, on the surface of this aluminum alloy plate,
When having a concentric annular groove having a surface roughness Ra of 2 μm or less, the adhesion of the coating film formed on the aluminum alloy plate is improved, and the formability such as bending property and overhang property of the material is further improved, In addition, sharpness can be given to the surface.

Further, the coating preferably contains lithium silicate having a SiO ₂ / LiO ₂ molar ratio of 18 to 33.

Further, the coating film is composed of a silicate compound 1
It is preferable to contain 5 to 100 parts by mass of the organic resin based on 00 parts by mass.

Further, the coating film is made of silicate compound 100
It is preferable to contain 1 to 30 parts by mass of the silane coupling agent with respect to parts by mass.

Further, the coating film is made of silicate compound 100
It is preferable that the solid lubricant is contained in an amount of 0.1 to 10 parts by mass with respect to parts by mass.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an aluminum alloy material coated with a coating film for a recording medium drive case (hereinafter, referred to as an aluminum alloy material) according to an embodiment of the present invention will be described.
In order to solve the above-described problems, the inventors of the present application have determined that an optimal strength, required conductivity, slidability (scratch resistance), fingerprint resistance, and the like of a drive case material using an aluminum alloy in a recording medium drive device. As a result of intensive experiments and research on the aluminum alloy composition and its surface treatment to obtain aluminum, we found the optimal Mg content to improve the strength of the aluminum alloy plate and formed micropores in the coating film formed on the aluminum alloy plate By doing so, it has been found that the conductivity required for the use of the drive case can be obtained.

In the present invention, Mg is added in the range of 2.0 to 6.
The surface of an aluminum alloy plate containing 0% by mass has fine pores, and the coating amount is 20 to 1000 m in terms of Si amount.
g / m ₂ of the coating film is formed. In the aluminum alloy plate, Mn is 0.5% by mass or less, Fe is 0.5% by mass or less, Si is 0.3% by mass or less, Cr is 0.5% by mass or less, and Cu is 0.5% by mass or less, as required. 3% by mass or less and 0.1% by mass or less of Ti are added. Also, this coating is
It is composed of a silicate compound, an organic resin, a silane coupling agent, and a solid lubricant.

As the organic resin, for example, urethane resins, acrylic resins, polyethylene resins, polyester resins, and modified resins of these resins can be used. In addition, among these resins, it is preferable to use a water-soluble urethane-based resin, an acrylic-based resin, a modified resin mainly containing these resins, and the like.

As the silane coupling agent, for example,
.gamma.-glycidoxyprimethoxysilane, .gamma.-glycidoxypropylmethyldimethoxysilane, .beta .- (3,4 epoxycyclohexyl) ethyltrimethoxysilane and the like can be used.

As the solid lubricant, for example, polyalkylene wax, polyalkylene oxide wax, microcrystalline, fluorine wax, PTEF wax, lanolin wax, carnauba wax, paraffin wax, graphite and the like can be used. Can be. It is preferable to use a water-dispersed type polyalkylene wax, a polyalkylene oxide wax, or the like.

The silicate compound and the organic resin constituting the coating material for forming the coating film alone have a high intrinsic volume resistivity and are insulating. However, when applying a paint containing an organic resin to a silicate compound to form a coating film,
Since the silicate compound and the organic resin have significantly different molecular cohesion energies, a layer separation phenomenon occurs between the silicate compound and the organic resin in the process of forming the coating film, and a film is formed while forming a sea-island structure. Therefore, micropores are generated in the coating film. The sea-island structure means that a plurality of components (for example, A and B) having different molecular cohesion energies form
The layer is separated into a rich layer and a B-rich layer and has a surface form like an island floating in the sea. In this case, pores are generated in a layer portion having a strong cohesive force. The inventors of the present application have made it possible for electrons to pass between the aluminum alloy plate and the surfaces of the coating films formed on both surfaces of the aluminum alloy plate by the micropores generated in the coating film in this manner. It has been found that it becomes conductive.

Further, since this coating film contains a hard silica component in the coating film, the hardness of the coating film is increased and the scratch resistance of the material surface is improved. Furthermore, since this coating film is formed by the silanol compound forming a silanol bond, the number of hydroxyl groups on the coating film surface is reduced by the dehydration condensation. Therefore, moisture and oil are less likely to adhere to the surface of the coating film, and when directly touching the surface of the material with bare hands, fingerprints due to moisture and oil such as sweat adhering to the hand are less likely to be transferred. That is, since it has good fingerprint resistance and does not cause deterioration in appearance due to fingerprint marks even when the material surface is touched with bare hands, the drive case is subjected to press forming and assembling after forming, as well as word processors, personal computers and Handling at the time of attaching and detaching the recording medium drive device to and from other computer-related devices and the like is improved.

When an organic resin is added, the stretchability of the coating film is improved. For this reason, the processability of the coating film itself is improved, and further, the film forming property of the coating film is improved, and thus the corrosion resistance is improved.

The silane coupling agent is an organic silane compound in which an organic group and a hydrolyzable alkoxide group are bonded to a Si atom. In the silane coupling agent, the alkoxide group reacts with an inorganic substance, and the organic group can bind to an organic resin or the like. Combine with the material surface. This bonding further strengthens the bonding between the components in the coating film, and further improves the adhesion of the coating film to the aluminum alloy material. Further, the workability is improved by improving the adhesion. Further, the bonding strength between the components in the coating film is strengthened, and the adhesion of the coating film to the aluminum alloy material is improved, so that the corrosion resistance is improved. Furthermore, the number of hydroxyl groups on the surface of the coating film is further reduced due to the bond between the organic group and the alkoxide group of the silane coupling agent, and the fingerprint resistance is further improved.

Further, when a solid lubricant is added to the coating film, it has an effect of improving the lubricity of the surface of the coating film, and improves the slidability (scratch resistance) of the material.

Since the aluminum alloy material having the coating film formed as described above has excellent conductivity, a method of directly connecting a ground wire to the drive case and a member having excellent conductivity on the drive case surface are used. In a method such as contact, sufficient electrical continuity is obtained at the contact point, so that the ground can be easily taken. Further, the aluminum alloy material has excellent slidability, fingerprint resistance and corrosion resistance, and has necessary and optimum strength and moldability as a material suitable for a drive case.

Hereinafter, the reasons for limiting the numerical values in the present invention will be described.

Mg content of aluminum alloy plate: 2.0
-6.0 mass% Mg has the effect of promoting work hardening during cold rolling of an aluminum alloy and improving the material strength. However, when the content of Mg is 2.0% by mass or less, the effect of improving the strength of the alloy is small. On the other hand, when the content of Mg is 6.0% by mass or more, rolling becomes difficult, and bending (90-0 ° R bending) performed when forming the upper lid and the lower lid of the drive case is performed. The formability such as the bending formability and the overhanging formability of the overhanging process is reduced. Therefore,
The Mg content of the aluminum alloy plate is set to 2.0 to 6.0% by mass.

The aluminum alloy of the present invention can further improve various material properties by adding Mn, Fe, Si, Cr, Cu and Ti as necessary.

Mn is added to an aluminum alloy as necessary because it has the effect of improving the material strength in the same manner as Mg. However, if the added amount exceeds 0.5% by mass, the material is bent. The productivity such as the property is reduced. Therefore, the preferred range of the Mn content is 0.5% by mass.
It is as follows.

Fe is added as necessary to the aluminum alloy because it has the effect of refining the crystal grains and improving the bending performance, but is added as necessary. A coarse intermetallic compound consisting of Al-Fe-Mn is formed. If such inclusions are formed, the inclusions will serve as starting points during the forming process to cause cracks, thus reducing the formability. Therefore, Fe
A preferable range of the content is 0.5% by mass or less.

Since Si has the effect of improving the material strength similarly to Mg and Mn by being added to the aluminum alloy, Si is added as necessary, but if the addition amount exceeds 0.3% by mass, intermetallic Invites coarsening of the compound,
Moldability such as bending workability of the material is reduced. Therefore, Si
A preferable range of the content is 0.5% by mass or less.

Cr is added to an aluminum alloy containing Mg as necessary, since Cr has the effect of controlling the stress corrosion cracking resistance of the aluminum alloy, but the amount of addition exceeds 0.5% by mass. In some cases, a coarse intermetallic compound of Al ₇ Cr and Al may be formed to lower the formability such as bending workability. Therefore, a preferable range of the Cr content is 0.5% by mass.

By adding Cu to the aluminum alloy, Cu has the effect of increasing the strength of the aluminum alloy and reducing the decrease in material strength that occurs during baking of the coating film.
It is added as needed, but if the addition amount exceeds 0.3% by mass, the formability such as rolling workability and bending workability and corrosion resistance deteriorate. Therefore, the preferable range of the added amount of Cu is 0.3% by mass or less.

When Ti is added to an aluminum alloy, it has the effect of refining the structure when the aluminum alloy is melted to form an ingot and has the effect of making the material characteristics uniform, and is added as necessary. If the amount exceeds 0.1% by mass, an extremely large intermetallic compound is formed during casting, which impairs formability such as bending of the material. Therefore, the preferable range of the Ti content is 0.1% by mass or less.

Tensile strength of coated aluminum alloy material:
210-410MPa, yield strength: 150-370MPa
a If the tensile strength and proof stress, which are the tensile properties of the aluminum alloy material coated with the coating film, exceed 410 and 370 MPa, respectively, the strength becomes too high, and the bending processability when forming into a drive case and the forming process such as overhang forming. Is reduced.
On the other hand, the tensile strength and proof stress are 210 and 150 MPa, respectively.
If it is less than this, the strength is low, and it is unsuitable for use as a drive case. Therefore, the tensile strength is 21
0 to 410 MPa, and proof stress is 150 to 370 MPa. In order to obtain the tensile properties of such an aluminum alloy material, the tensile strength of the aluminum alloy plate before forming the coating film must be at least 210 to 410 MPa.
And the proof stress is set to 150 to 370 MPa.

Average diameter of pores of coating film: 1.0 μm or less When pores are formed in the coating film, the coating film becomes conductive, but the average diameter of the pores is 1.0 μm. If it becomes larger, the portion becomes a coating film defect, and at this coating film defect, the material is easily corroded, and the corrosion resistance is reduced. Therefore, the average diameter of the pores of the coating film is 1.0 μm or less.

Coating amount: 20 to 1000 m in terms of Si amount
When the amount of the g / m ² coating film is less than 20 mg / m ^{2 in} terms of Si amount, since the coating film is thin, sufficient conductivity can be obtained.
The effect of improving the above-described slidability, fingerprint resistance, and corrosion-resistant workability cannot be sufficiently obtained, and is unsuitable for use in a drive case. In addition, the coating amount is 1000 m in terms of Si amount.
When the thickness is more than g / m ² and the thickness of the coating film is large, pores formed in the coating film penetrate the coating film from the surface of the aluminum alloy material, reach the coating film surface, and are not easily formed. This makes it difficult for electrons to pass through the pores, and reduces the conductivity. Therefore, the coating amount is 20 to 1000 mg / m ^{2 in} terms of Si amount.
And

Surface resistance value: 20 Ω or less When the surface resistance value of the coating film is larger than 20 Ω, when a drive case is formed using this aluminum alloy material,
When the drive case is grounded directly by grounding the drive case or by contacting the surface of the drive case with a highly conductive member, sufficient conductivity cannot be obtained at the contacts, and the drive unit Since it is not possible to sufficiently prevent a small current from flowing into the drive device, the memory of the recording medium contained in the drive device is hindered. Therefore, the surface resistance is set to 20Ω or less. Such a surface resistance value can be determined by the following method.

FIG. 1 is a schematic diagram showing a method of measuring a surface resistance value. As shown in FIG. 1, the tip 2a of a rod 2 made of brass having a weight of about 40 g is brought into contact with the surface of an aluminum alloy material 1 having a coating film 1a formed on both surfaces of an aluminum alloy plate 1b. The tip radius of this rod 2 is 10 m
m. Then, the tester 3 is connected to the other end 2b of the rod 2, the tester 3 is connected to the aluminum alloy plate 1b,
The aluminum alloy plate 1b and the tester 3 are conducted. This allows the tester 3 to measure the surface resistance value of the coating film 1a on the aluminum alloy material 1.

[0051]SiO _{2 of} coating film / Li ₂ O (molar ratio): 18
Thirty-three As silicate compounds, sodium silicate, silicic acid
And potassium salt and lithium silicate. Silicate Na
Forming coatings using thorium and potassium silicate
The sodium ions and potassium remaining in the coating
Due to the absorption of ions, defects occur in the coating film,
May deteriorate eating habits. This kind of coating defects
In order not to generate, as the silicate compound used,
Lithium silicate is preferred. Any silicate compound
When using _TwoO / X_TwoO (molar ratio)
(X: Na, K and Li) should be 18 to 33
Is preferred. Sodium silicate as silicate compound
When using less than 18, the coating film component, especially Li
The components are easily eluted, and the corrosion resistance is reduced. On the other hand, Si
O_Two/ Li_TwoWhen O is larger than 33, the film forming property of the coating film is reduced.
And the wettability between the aluminum alloy material and the coating film
Adhesion to aluminum alloy material
descend. This causes cracks in the formed coating and
At the same time, the corrosion resistance decreases and the scratch resistance decreases.
Therefore, Si_TwoO / Li_TwoO (molar ratio) is 18 to 33
Is preferred.

Organic resin content of coating film: silicate compound 1
When the content of the organic resin is 5 to 100 parts by mass with respect to 00 parts by mass, and less than 5 parts by mass with respect to 100 parts by mass of the silicate compound, the layer separation effect between the silicate compound and the organic resin becomes insufficient, Since the number of pores formed in the coating film is reduced, the conductivity becomes insufficient, and the effect of improving corrosion resistance and coating film processing performance by adding an organic resin is not sufficiently obtained. On the other hand, if the content is more than 100 parts by mass with respect to 100 parts by mass of the silicate compound, the neutralization phenomenon between the silicate compound and the organic resin proceeds excessively, and the stability of the coating material decreases. As a result, the paint gels and cannot be applied to the aluminum alloy plate. Therefore, the content of the organic resin is preferably set to 5 to 100.

The silane coupling agent content of the coating film: 1
If the amount of the silane coupling agent is less than 1 part by mass, a sufficient effect of improving scratch resistance, coating film processability, corrosion resistance and fingerprint resistance cannot be obtained. On the other hand, when the content is more than 100 parts by mass, the silane coupling reaction progresses too much, and the stability of the coating material forming the coating film decreases, and in severe cases, the coating material gels and the coating operation cannot be performed. I will. Therefore, the content of the silane coupling agent is preferably 1 to 30 parts by mass.

Content of solid lubricant in coating film: 0.1 to 1
If the content of the 0 parts by weight solid lubricant is less than 0.1 parts by weight, the effect of improving the lubricity of the coating film surface is not sufficiently obtained, and the slidability (scratch resistance) of the material surface is sufficiently improved. Can not be obtained. On the other hand, when the content of the solid lubricant exceeds 10 parts by mass, the film-forming properties are reduced, and thus the corrosion resistance and the scratch resistance of the formed coating film are deteriorated. Therefore, the content of the solid lubricant is preferably 0.1 to 10 parts by mass.

The surface roughness Ra of the aluminum alloy plate is 2.
By regulating the surface shape of the aluminum alloy plate on which the concentric annular groove coating of 0 μm or less is formed, the forming process such as the adhesion between the aluminum alloy plate and the coating film and the bending property and overhang property of the aluminum alloy material. Properties can be further improved, and sharpness can be imparted to the material surface. However,
When the surface roughness Ra exceeds 2.0 μm, the rolled marks on the rolled marks are coarse and the streaks are conspicuous, impairing the appearance,
It is unsuitable for the use of the present invention. If the surface roughness Ra is 0.1 μm or less, the above-mentioned effects are not sufficiently exhibited,
Further, the glossiness of the material becomes too high, and the scratches are easily noticeable.
Therefore, the surface shape of the aluminum alloy plate has a surface roughness R
a is a concentric annular groove having a surface roughness R of 0.2 μm or less.
a is preferably 0.1 μm or more.

Next, a method for manufacturing such an aluminum alloy material will be described. First, an aluminum alloy having the above-described composition is melted and made into an ingot by continuous casting. Then, for example, a homogenization treatment is performed at a temperature of 500 ° C. for 8 hours. Next, the ingot subjected to the homogenization treatment is subjected to hot rolling or hot rolling and cold rolling to be rolled to a desired thickness. Thereafter, intermediate annealing is performed at a temperature of 350 ° C. or more, and final cold rolling is performed at a final rolling reduction of 20 to 90%. Thereafter, a coating material is applied to the aluminum alloy plate which has been subjected to a stabilizing treatment and a pre-coating treatment, if necessary, and dried, whereby an aluminum alloy material having a coating film formed thereon can be obtained. At this time, the diameter of the pores formed in the coating film can be regulated by the type of the silicate compound and the organic resin of the coating material used for forming the coating film and the compounding ratio thereof. Also,
The coating film can be formed by applying a coating material by a method such as a roll coater method, heating the coating material to reach a temperature of 100 to 300 ° C., and drying for 5 to 120 seconds.

The intermediate annealing is performed prior to final cold rolling in order to obtain appropriate strength characteristics and workability. This is for recrystallizing the aluminum alloy sheet by the intermediate annealing, and therefore, is performed at a temperature higher than the recrystallization temperature, preferably higher than 350 ° C.

In the final cold rolling, the rolling reduction is 2
If it is less than 0%, sufficient strength cannot be obtained. On the other hand, if the rolling ratio exceeds 90%, the formability such as bending property and overhang property deteriorates. Therefore, the final cold rolling reduction is preferably set to 20 to 90%.

Further, the surface roughness Ra of the aluminum alloy sheet formed by the final rolling in the final pass of the final cold rolling is set to 0.1 to 2.0 μm, or the surface roughness Ra is set to 2.0 μm or less. To form a concentric annular groove pattern. In the finishing stage of the final cold rolling, such a surface shape is formed as a regular pattern by a polishing roll using a grindstone, a sand shot roll (shot dull roll) or a laser beam, for example, an outer diameter of 200 μm, and a surface roughness. Can be formed by performing rolling using a rolling roll (laser dull roll) having a concentric annular groove having a diameter of 2 μm or less.

After the finish rolling, a stabilizing treatment may be performed at a temperature of 250 ° C. or lower, if necessary. When a heat treatment at a temperature exceeding 250 ° C. is performed as the stabilization treatment, the strength of the aluminum alloy sheet tends to decrease, and therefore the stabilization treatment temperature is preferably set to 250 ° C. or less. If the heat treatment temperature is lower than 150 ° C., the strength required for the present invention may not be stably obtained.
More preferably, the stabilization treatment is performed at a temperature of ° C.

[0061] After the stabilization treatment or the one not subjected to the stabilization treatment, after the final cold rolling, a pre-coating treatment before forming a coating film on the aluminum alloy plate may be performed. As a pre-coating treatment, phosphoric acid chromate treatment (Cr amount 5 to 4)
0 mg / m ² ) and an undercoating film containing chromium ions, such as a coating type chromate treatment, and an undercoating film containing zirconium ions, titanium ions, manganese ions, and the like can be formed.

As described above, since the surface of the aluminum alloy plate after the final cold rolling has an appropriate surface roughness Ra, the adhesion between the coating film formed thereafter and the aluminum alloy plate is excellent, and the recording medium drive case is formed. The coating film is hardly peeled off at the time of the forming process for forming the film, and the surface can be provided with sharpness. Further, by performing intermediate annealing, final cold rolling and stabilizing treatment under optimum conditions, the strength characteristics and bending property (90 ° -0R) as a recording medium drive case are obtained.
Bending) and overhanging properties can be obtained.

Further, by performing the pre-coating treatment to form the undercoating film, the adhesion between the aluminum alloy plate and the coating film is improved, and the corrosion resistance is further improved. In addition, the sliding between the aluminum alloy material and the press mold during press forming and the sliding between the computer-related equipment and other parts when attaching and detaching the drive case device made of the coated aluminum alloy material to the computer-related equipment. It is possible to suppress the peeling of the coating film which is likely to occur due to the above and the like and the generation of the peeled product.

[0064]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples that fall outside the scope of the present invention.

Example 1 An aluminum alloy having the composition shown in Table 1 below was melted by a conventional method and cast into an ingot by continuous casting. Next, the ingot was subjected to a homogenization treatment at a temperature of 500 ° C. for 8 hours.
Hot rolling was performed to obtain a plate having a thickness of 3.5 mm. Next, 4
After the intermediate annealing at a temperature of 20 ° C., the sheet thickness is 0.8 mm
, And a stabilization treatment was performed at a temperature of 240 ° C. For some of the materials, finish rolling was performed using shot dull and radar dull rolls in the final pass in the final cold rolling to obtain sheet materials having different surface conditions. The surface roughness of the formed aluminum alloy sheet material is measured using a surface roughness meter (Surface Roughness Tester; Surfcoder S)
E-3D-D; manufactured by Kosaka Laboratory Co., Ltd.).

Further, using this plate material, in order to measure the tensile performance between the aluminum alloy material after forming the coating film and the aluminum alloy plate before forming the coating film, a test piece of JIS No. 5 was used to determine the aluminum alloy material before forming the coating film. The tensile performance of the alloy material was measured.

Next, after both surfaces of the prepared plate material were subjected to phosphoric acid chromate treatment (Cr content: 20 mg / m ² ), the amount of the coating film to be formed was changed using paints containing various conductive substances. Test material was prepared.

The coating amount of the test material was determined in terms of Si amount. S
The i amount was measured by X-ray fluorescence. The average diameter of the pores formed in the coating film formed on the test material was measured using a scanning electron microscope (FE).
-SEM; manufactured by JEOL Ltd.), the average value of pores present on the surface of the coating film in a square region having an arbitrary length and width of 20 μm was determined. Furthermore, the tensile performance of the test material
It was measured by a method similar to that for an aluminum alloy material before forming a coating film on an IS No. 5 test piece. The results are shown in Tables 2 to 5 below.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

[Table 3]

[0072]

[Table 4]

[0073]

[Table 5]

In Tables 2 and 4, "normal" shown in the surface condition means "grinding wheel", "S / D" means a shot dull roll, and "R / D" means a laser dull roll. Shows the type of rolling roll used for finish rolling. In the coating film components, the molar ratio of the silicate compound is SiO ₂ / X ₂ O (molar ratio),
X represents Li, Na and K, and represents the type of the silicate compound. A1 represents lithium silicate, B1 represents sodium silicate, and C1 represents potassium silicate. The contents shown in the organic resin, the silane coupling agent and the solid lubricant refer to the silicate compound 1 respectively.
The content parts by mass are shown with respect to 00 parts by mass. Further, A2 of the type of the organic resin indicates a water-soluble urethane resin, and B2 indicates a water-soluble acrylic resin. A3 of the silane coupling agent type is γ-glycidoxypropyltrimethoxysilane, B3 is γ-glycidoxypropylmethyldimethoxysilane, and C3 is β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane. . Further, the types of solid lubricants A4 indicate polyethylene wax, and B4 indicates oxidized polyethylene wax. The amount of the coating film is expressed in terms of Si amount (mg / m ² ). The same applies to the following tables.

The following measurements were respectively performed to evaluate the material properties of the obtained test materials. The measurement results and evaluation are shown in Tables 6 and 7 below.

The tensile performance of the test material was measured using a JIS No. 5 test piece in the same manner as the aluminum alloy plate before the coating film was formed.
The tensile strength, proof stress and elongation were measured.

With respect to the conductivity of the test material, the surface resistance of the test material surface was measured by the method described above.

As for the slidability (scratch resistance), the surface of the test material had a diameter of 4.
A hard sphere of 23 (mm) was brought into contact, and sliding was repeated at the same position at a speed of 4 mm / sec with a load of 200 g. Then, the number of sliding times at which a scratch was generated on the surface of the test material to reach the aluminum alloy plate on which the coating film was formed was measured. If the number of times of sliding exceeds 5 times, ◎ is given.
The sample was evaluated as ○ when the number of slides exceeded 2 times, Δ when the number of slides was 2 or 3 times, and × when the number of slides was 1 or less.

Regarding the fingerprint resistance, a finger is pressed onto the surface of the test material with a finger of a bare hand to attach a fingerprint. Was. If the color difference value is smaller than 0.5 and the fingerprint is hardly noticeable, the result is ○.
When the fingerprint was slightly conspicuous between 5 and 1.5, the evaluation was Δ, and when the color difference value exceeded 1.5, the fingerprint was evaluated as X.

Regarding corrosion resistance, JIS Z 2371
The presence or absence of corrosion after the 96-hour salt water fountain test was examined. Then, the rating No. A rating exceeding 9.8 is rated as “◎”. If the rating exceeds 9.5, the rating is No. 9 to 9.5, and rating No. 9 or less were evaluated as x.

Regarding the peeling state and the bending workability of the coating film, a 90 ° -0R bending test was performed using the thickness of the test material as a bending radius, and the bent portion was observed with a stereoscopic microscope at a magnification of 50 to 200 times. Then, the state of peeling of the coating film was examined, and the bending workability was evaluated from the state of cracking. Regarding the evaluation of the state of peeling of the coating film, those without peeling were evaluated as ○, those with slight peeling of the coating film were evaluated as Δ, and those with severe degree of peeling were evaluated as x. In addition, as for evaluation of bending workability, those having no crack were evaluated as ○,
も の for those with minute cracks, × for those with large cracks
Was evaluated.

[0082]

[Table 6]

[0083]

[Table 7]

In Examples 1 to 23, since the Mg content was within the range of the present invention, there was almost no change in the mechanical properties before and after the application of the paint, and all exhibited good tensile performance. In addition, since the coating film satisfying the scope of the present invention is formed in each of the test materials, the sliding property (scratch resistance), fingerprint resistance, corrosion resistance, peeling state of the coating film (adhesion), and bending workability are considered. Excellent performance was demonstrated.

In Example 24, the SiO ₂ /
Since Li ₂ O (molar ratio) was less than the preferred range of the present invention, the corrosion resistance was slightly reduced. In Example 25, since the SiO ₂ / Li ₂ O (molar ratio) of the formed coating film exceeded the preferred range of the present invention, the slidability, corrosion resistance, and adhesion of the coating film were slightly lowered. In Example 26, the content of the organic resin in the formed coating film was less than the preferred range of the present invention, and in Example 27, the content of the silane coupling agent in the formed coating film was preferable in the present invention. Since it is less than the range, slidability, fingerprint resistance, corrosion resistance, and adhesion of the coating film were slightly lowered. In Example 28, since the content of the solid lubricant in the formed coating film exceeded the preferred range of the present invention, the slidability, corrosion resistance, and adhesion of the coating film were slightly lowered. In Example 29, since the content of the silane coupling agent in the formed coating film exceeded the preferred range of the present invention, the slidability, corrosion resistance, and adhesion of the coating film were slightly lowered. In Example 30, since the content of the solid lubricant in the formed coating film was less than the preferred range of the present invention,
Although the slidability was reduced, other characteristics were favorable.

Comparative Example 1 showed excellent conductivity because no coating film was formed, but was poor in slidability, fingerprint resistance, corrosion resistance and the like. Comparative Example 2 did not contain an organic resin, a silane coupling agent and a solid lubricant in the formed coating film, so that no fine pores were formed in the coating film, and therefore, the surface resistance was large and the conductivity was poor. Was. In addition, the slidability, fingerprint resistance, corrosion resistance, and adhesion of the coating film were poor.

Comparative Example 3 exhibited good conductivity because the formed coating film did not contain a silane coupling agent and a solid lubricant, but was inferior in slidability, corrosion resistance and adhesion of the coating film. . In Comparative Example 4, since the formed coating film did not contain a solid lubricant, good conductivity was exhibited, but slidability was poor. In Comparative Example 5, since the formed coating film did not contain a silane coupling agent, it exhibited good conductivity but was inferior in corrosion resistance.

In Comparative Example 6, since the coating amount of the formed coating film was less than the lower limit of the range of the present invention, good conductivity was exhibited, but a sufficient effect on the sliding property, fingerprint resistance and corrosion resistance was obtained. Could not be obtained. In Comparative Example 7, since the coating amount of the formed coating film exceeded the upper limit of the range of the present invention, the conductivity was poor, and the internal stress of the coating film was increased, so that the coating film adhesion was insufficient. Comparative Example 8, since the average diameter of the pores of the formed coating film exceeded the range of the present invention, the corrosion resistance was poor.

In Comparative Example 9, since the content of Mg was low and less than the lower limit of the range of the present invention, sufficient mechanical strength was not obtained after the heat treatment under stable conditions, and the tensile strength after the formation of the coating film was lowered. The strength was insufficient for use as a material for a recording medium drive case.

Second Embodiment Table 1 shown in Table 1 used in the first embodiment An aluminum alloy having an alloy composition of No. 1 was melted by an ordinary method and continuously cast to form an ingot. Then, homogenization treatment, hot rolling, intermediate annealing and final cold rolling were performed in the same steps as in the first embodiment. Alms, 20
A stabilizing treatment was performed at 0 to 300 ° C. to form a 0.8 mm-thick plate. Note that only the test material of Example 41 was not subjected to the stabilization treatment. In Examples 31 to 40 and 42, after the stabilization treatment, and in Example 41, after the final cold rolling,
A test material having a coating film formed thereon was prepared in the same manner as in the example. The coating film is made of a silicate compound (lithium silicate) 100
Resin containing 20 parts by mass of an organic resin (water-soluble acrylic resin), 10 parts by mass of a silane coupling agent (γ-glycidoxypropyltrimethoxysilane) and 1 part by mass of a solid lubricant (polyethylene wax) based on parts by mass. It was formed by applying a coating material to an aluminum alloy plate so that the coating amount was 250 mg / m ^{2 in} terms of Si amount. Table 8 below
And 9 show the manufacturing conditions of this test material. The prepared test materials were evaluated for tensile performance, conductivity, slidability, and the like in the same manner as in the first example. Regarding the surface quality, ○ indicates that the surface was good, and X indicates that the surface roughness was large. The results are shown in Table 10 below.

[0091]

[Table 8]

[0092]

[Table 9]

[0093]

[Table 10]

In Examples 31 to 40, since the production conditions were within the preferable range of the present invention, the mechanical properties of the test material were hardly changed after the formation of the coating film as compared with before the formation. , All showed good tensile performance. In addition, in each of the test materials, the surface resistance was as extremely small as 20 Ω or less, and had good conductivity. In addition, extremely good results were obtained in terms of slidability, fingerprint resistance, corrosion resistance, paint releasability, and bending workability.

In Examples 42 and 43, since the surface roughness Ra was out of the preferred range of the present invention, Example 42 had finer rolls, respectively, increased the glossiness of the test material surface, and slightly reduced the slidability. In Example 43, although the surface roughness increased, the fingerprint resistance, corrosion resistance, coating film peeling property, and bending workability were excellent.

In Comparative Examples 10 to 14, any one of the manufacturing conditions was out of the preferred range of the present invention, so that any of the properties required as the material used as the recording medium drive case was inferior, and the recording medium drive case was inferior. It was unsuitable as a material.

In Comparative Example 10, the strength was insufficient because the stabilization temperature exceeded the preferred range of the present invention. In Comparative Example 11, since the final cold rolling ratio was out of the preferred range of the present invention, the mechanical properties were inferior, and the strength as a material for a recording medium drive case was insufficient. In Comparative Example 12, since the final cold rolling ratio exceeded the preferred range of the present invention, the strength was too high and the bending workability was deteriorated. Comparative Example 13
However, since the Mg content of the aluminum alloy plate exceeded the preferred range of the present invention, sufficient strength was not obtained after the stabilizing heat treatment. In Comparative Example 14, since the amount of the coating film exceeded the upper limit of the range of the present invention, the conductivity was lowered and the adhesion of the coating film to the aluminum alloy material was lowered due to an increase in the internal stress of the coating film.

Third Embodiment A stabilizing material for an aluminum alloy plate prepared by the same composition and manufacturing method as in the first embodiment used in the first embodiment is used, and a coating film is formed on this aluminum alloy plate. Prior to the application of the coating material, a base treatment shown in Table 11 below was performed. Thereafter, a test material having a coating film formed on the aluminum alloy plate subjected to the base treatment in the same manner as in the first embodiment. With respect to 100 parts by mass of lithium silicate having a molar ratio of SiO ₂ / Li ₂ O of 27,
Using a resin paint containing 20 parts by mass of an organic resin (water-soluble acrylic resin), 10 parts by mass of a silane coupling agent (γ-glycidoxypropyltrimethoxysilane) and 1 part by mass of a solid lubricant (polyethylene wax), The coating was applied to an aluminum alloy plate so that the coating amount was 250 mg / m ^{2 in} terms of the amount of Si. Then, for these test materials, the conductivity, slidability, fingerprint resistance, film peeling state and bending workability were measured in the same manner as in the first example. The evaluation results are shown in Table 12 below.

[0099]

[Table 11]

[0100]

[Table 12]

As shown in Table 12, Examples 44 to 48
Shows that the surface treatment value was extremely low because the undercoating film was formed within the preferable range of the present invention, and the material properties of each of the examples were lower than those of Example 1 without the undercoating film. Improved.

[0102]

As described above in detail, according to the present invention, since the aluminum alloy plate contains 2.0 to 6.0% by mass of Mg, a coating film having high strength and pores is formed. Therefore, it has excellent corrosion resistance, fingerprint resistance, slidability and corrosion resistance, and also has excellent conductivity. As a result, the ground can be easily taken, the surface is hardly scratched, the fingerprint is hardly noticeable, and the weight is light, so that an aluminum alloy material for a recording medium drive case can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for measuring a surface resistance value according to the present invention.

[Explanation of symbols]

 1; aluminum alloy material 2; rod 2a; tip 2b; other end 3: tester

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuo Hattori 15 Kinuigaoka, Moka-shi, Tochigi F-term in Kobe Steel Moka Works (reference) 4F100 AA03B AA03C AB09B AB09C AB10A AB11B AB11C AB31A AH06B AH06C AK01B AK01C AK04 AK25 AL06 BA02 BA03 BA06 BA07 BA10B BA10C CC00B EJ19 EJ192 EJ67B EJ69 EJ692 GB41 JB02 JG01 JG04B JG04C JK02B JK02C JK16 YY00A YY00B YY00C

Claims (6)

[Claims] An aluminum alloy plate containing Mg: 2.0 to 6.0% by mass, and a silicate compound on the surface thereof.
A coating comprising an organic resin, a silane coupling agent and a solid lubricant, wherein the coating has a coating amount of 20 in terms of Si content.
To 1000 mg / m ² , having pores with an average diameter of 1 μm or less on the surface, having a surface resistance of 20 Ω or less, an overall tensile strength of 210 to 410 MPa, and a proof stress of 150 to 370 MPa. An aluminum alloy material coated with a coating film for a recording medium drive case. 2. A coating-coated aluminum alloy material for a recording medium drive case according to claim 1, wherein the aluminum alloy plate has a concentric annular groove having a surface roughness Ra of 2 μm or less on the surface. 3. The coating film for a recording medium drive case according to claim 1, wherein the coating film contains lithium silicate having a SiO ₂ / LiO ₂ molar ratio of 18 to 33. Aluminum alloy material. 4. The recording medium drive according to claim 1, wherein the coating film contains 5 to 100 parts by mass of an organic resin with respect to 100 parts by mass of a silicate compound. Aluminum alloy material coated with coating for case. 5. The film according to claim 1, wherein the coating film contains 1 to 30 parts by mass of a silane coupling agent with respect to 100 parts by mass of the silicate compound. Aluminum alloy material coated with coating film for recording media drive case. 6. The coating film according to claim 1, wherein the coating film contains 0.1 to 10 parts by mass of a solid lubricant based on 100 parts by mass of the silicate compound. Coated aluminum alloy material for recording media drive cases.