JP2008114194A - Precoat aluminum alloy plate for case - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precoat aluminum alloy plate which can use suitably as a case of a notebook-sized personal computer, etc. <P>SOLUTION: The precoat aluminum alloy plate has chemical coats deposited on both sides of the aluminum alloy plate, a resin coat A on at least one of the chemical coats and a colored resin coat B on it, wherein any one or both the resin coat A and the colored resin coat B have 15-150 glass beads in the range of the maximum diameter of a particle of 5-70 μm within the width of 5 mm in the rectangular direction to the coating direction, the coat thickness is in the range of 7-20 μm and the coefficient of kinetic friction of the colored resin coat B is preferably in the range of 0.03-0.20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a precoated aluminum alloy plate used for a housing of an electric / electronic device such as a notebook computer.

  2. Description of the Related Art Conventionally, as an outer shell housing for storing an electronic device such as a semiconductor device, a thermoplastic resin manufactured by injection molding has been often used.

  Recently, the market for electronic devices such as portable notebook PCs is expanding, but in such applications, miniaturization, weight reduction, and thinning have progressed dramatically. It has become impossible to support. This is because the strength of the conventional resin casing is weak when the wall thickness is reduced. Therefore, metal housings such as magnesium and aluminum capable of satisfying requirements such as electromagnetic shielding and heat dissipation are increasing. Metal casings also have the advantage of easy material recycling.

When aluminum is used for a metal casing, an aluminum plate is formed by press molding, and a method of coating the outer surface with a paint having an alumite or pencil hardness of 2H to 7H is disclosed (Patent Document 1).
JP 2004-335644 A

These films are hard and are intended to make the film difficult to scratch.
Usually, these films are formed after press molding, but there is a problem that the cost is increased due to low productivity. On the other hand, a method of coating before press molding, that is, a method using a precoat is desired.
The precoat metal plate which has abrasion resistance is disclosed by patent document 2 and patent document 3. FIG.
JP-A-7-256821 JP 2002-178447 A

However, the inventions disclosed in Patent Document 2 and Patent Document 3 have the disadvantage that the wear resistance required for the outer surface of the notebook personal computer casing cannot be sufficiently satisfied.
An object of this invention is to provide the precoat aluminum alloy plate which can be used suitably for notebook computer housings.

  The invention according to claim 1 of the present invention is a precoated aluminum alloy plate having a conversion coating formed on both surfaces of an aluminum alloy plate, a resin coating A on at least one of the conversion coatings, and a colored resin coating B thereon. , Either or both of the resin film A and the colored resin film B contain 15 to 150 glass beads having a maximum major axis in the range of 5 μm to 70 μm between 5 mm and 5 mm in the direction perpendicular to the coating direction. The film thickness is in the range of 7 μm to 20 μm.

  In the invention according to claim 2, when both the resin film A and the colored resin film B contain glass beads, 60 glass beads are contained in the resin film B in a direction 5 mm perpendicular to the coating direction. The precoated aluminum alloy plate for a casing according to claim 1, wherein the number is in a range of ˜70.

  The invention according to claim 3 is the precoated aluminum alloy plate for a casing according to claim 1 or 2, wherein the colored resin film B has a dynamic friction coefficient in the range of 0.03 to 0.20. is there.

  The pre-coated aluminum alloy plate for a notebook personal computer casing of the present invention contains glass beads in the resin film A or the colored resin film B, the particle size of the glass beads is in a predetermined range, the film thickness is in a predetermined range, By setting the density of the beads within a predetermined range, the hardness of the entire resin film can be increased, so that the wear resistance can be improved. Moreover, since the lubricity of the colored resin film B is in a predetermined range, moderate lubricity is imparted and wear resistance can be improved. Due to the synergistic effect of the appropriate hardness of the resin film A and the lubricity of the colored resin film B, the wear resistance required for the outer surface of the notebook personal computer casing can be imparted.

A. Aluminum alloy plate The aluminum alloy used in the present invention is not particularly limited as long as it has good dent resistance and has sufficient moldability to form a notebook computer casing. Here, the dent resistance is the difficulty of leaving a dent (indentation) when a local force is applied to the material. In particular, JIS 5000 series aluminum alloy is preferable.

B. Chemical conversion film The chemical conversion film is not particularly limited as long as it is interposed between the surface of the aluminum alloy plate and the coating film to enhance the adhesion between them. For example, for aluminum alloys, a chemical conversion film formed with a phosphoric acid chromate treatment solution that is inexpensive and easy to manage the bath solution, or a chemical conversion coating formed by a coating-type zirconium treatment that does not require changes in the treatment solution components and does not require washing with water. Can be used. Such a chemical conversion treatment is performed by spraying a predetermined chemical conversion treatment solution on the aluminum alloy plate or immersing the aluminum alloy plate in the treatment solution at a predetermined temperature for a predetermined time.
Before the chemical conversion treatment, in order to remove dirt on the surface of the aluminum alloy plate or to adjust the surface properties, the aluminum alloy plate is acid-treated (washed) with sulfuric acid, nitric acid, phosphoric acid, or the like, or It is desirable to perform alkali treatment (cleaning) with caustic soda, sodium phosphate, sodium silicate, or the like. Surface treatment by such cleaning is also performed by spraying a predetermined surface treatment liquid on the aluminum alloy plate or immersing the aluminum alloy plate in the treatment liquid at a predetermined temperature for a predetermined time.

C. Resin film A
Next, a resin film layer A is formed on the chemical conversion film. The resin film A is formed by baking a paint in which a thermosetting resin is dissolved or dispersed in an appropriate solvent.

C-1. Film thickness of the resin film A The film thickness of the resin film A was set to 7 μm to 20 μm. If it is less than 7 μm, the cushion effect of the resin film A cannot be obtained, and the wear resistance is inferior. On the other hand, if it exceeds 20 μm, the film cannot follow the bending process, and the bending processability is inferior.

C-2. Glass Beads The glass beads had a maximum long diameter of 5 μm to 70 μm. The particle size can be measured by microscopy. When it is less than 5 μm, the wear resistance is poor. On the other hand, if it exceeds 70 μm, the film cannot follow the bending process, and the bending processability is inferior.

  There were 15 to 150 glass beads between 5 mm in the direction perpendicular to the coating direction. Observe the cross section of the coating film in a direction perpendicular to the arbitrarily selected coating direction with an optical microscope, measure the number of glass beads existing at an arbitrary distance, and exist between 5 mm perpendicular to the coating direction. It can be determined by a method of calculating the number of glass beads. By including glass beads in the resin film A, the resin film A becomes hard, so that the wear resistance can be improved. If it is less than 15, the occupation area of the portion where the beads do not exist becomes large, so the wear resistance is inferior. On the other hand, when the number exceeds 150, bending workability is inferior because it becomes a starting point of film cracking during bending.

  The addition amount of the glass beads is preferably 2% to 20% with respect to the resin solid content. If it is less than 2%, since the hardness of the resin film A is insufficient, the wear resistance is poor. If it exceeds 20%, it becomes a starting point of film cracking at the time of bending, so that bending workability is inferior.

C-3. Resin used A thermosetting resin is used as the resin used for the resin film A.
There is no restriction | limiting in particular in a thermosetting resin, For example, an epoxy-type resin, a fluorine-type resin, an acrylic resin, and a polyester-type resin can be used. Among them, it is preferable to use a polyester resin that is less likely to cause coating film cracking during processing such as press processing, has good workability during coating, and is advantageous in terms of cost.
The polyester resin is a resin obtained by combining dicarboxylic acid and diol.
Examples of the dicarboxylic acid include fatty acid dicarboxylic acids having 2 to 22 carbon atoms such as succinic acid, adipic acid, azelaic acid, and sebacic acid, and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. These dicarboxylic acids may be used alone or in combination of two or more.
Examples of the diol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol, 1,6- Examples thereof include fatty acid diols having 2 to 22 carbon atoms such as hexanediol, diethylene glycol, and pentanediol. These diols may be used alone or in combination of two or more.
Examples of linear polyester resins composed of dicarboxylic acid and diol structural units include linear polyester resins obtained by polycondensation of dicarboxylic acid and diol, and linear polyester resins obtained by addition reaction of dicarboxylic acid anhydride and diol. Furthermore, linear polyester resins obtained by transesterification can be mentioned, and not only linear polyester resins whose raw materials are dicarboxylic acid and diol, but the structural units in the linear polyester resin are from dicarboxylic acid. Those having the same structure as the structural unit derived from diol and the structural unit derived from diol are also included.
Although there is no restriction | limiting in particular in a hardening | curing agent, It is preferable to use methylated melamine resin, butylated melamine resin, and isocyanate resin.
In addition to the polyester resin and the curing agent, an epoxy resin or an acrylic resin may be mixed.

C-4. Additives In addition, the paints used in the present invention include pigments, pigment dispersants, fluidity modifiers, leveling agents, anti-cracking agents that are used in ordinary paints to ensure paintability and general performance as a precoat material. Agents, preservatives, stabilizers and the like may be added as appropriate.

C-5. Coating film formation A thermosetting resin is an essential component, and the above glass beads and additives are added as appropriate, and a paint in which these are dissolved or dispersed in an appropriate solvent is directly applied onto the chemical conversion film with a roll coater, and a predetermined temperature is applied. And baking for a predetermined time in the oven. In addition, it may replace with a roll coater and may apply | coat a coating material with an air spray, a bar coater, etc.

D. Colored resin film B
A colored resin film B is further formed on the resin film A. The colored resin film B is formed by baking and painting a paint in which a pigment and a lubricant are contained as essential components in a thermosetting resin and these are dissolved or dispersed in an appropriate solvent.

D-1. Dynamic friction coefficient The dynamic friction coefficient was in the range of 0.03 to 0.20. Abrasion resistance can be improved by imparting lubricity to the coating surface. If it is less than 0.03, the slipperiness of the coating surface is too good to be coiled up. When it exceeds 0.20, the wear resistance is inferior.

D-2. Film thickness of the colored resin film B The film thickness of the colored resin film B was set to 7 μm to 20 μm. When it is less than 7 μm, the cushioning effect of the colored resin film B cannot be obtained and the wear resistance is inferior. On the other hand, if it exceeds 20 μm, the film cannot follow the bending process, and the bending processability is inferior.

D-3. Thermosetting resin There is no particular limitation on the thermosetting resin, and it is possible to use, for example, an epoxy resin, a fluorine resin, an acrylic resin, or a polyester resin in the same manner as the thermosetting resin used for the resin film A. it can. Among them, it is preferable to use a polyester resin that is less likely to cause coating film cracking during processing such as press processing, has good workability during coating, and is advantageous in terms of cost. In particular, a polyester resin using a methylated melamine resin as a curing agent can harden the film, and therefore, it is preferable because stain resistance can be made relatively good while maintaining good processability.

D-4. Pigment The colored resin film B preferably contains a pigment for coloring. There are no particular restrictions on the type of pigment. For example, it is preferable to contain an aluminum pigment. The aluminum pigment is not particularly limited, and a bright aluminum pigment or a colored aluminum pigment can be used. As the shape of the glittering aluminum pigment, either a CORN FLAKE type in which the shape of the particles is nonuniform or a disk shape / coin-shaped SILVER DOLLAR type in which the edge portion is smooth can be used. Colored aluminum pigments include pigment-colored aluminum pigments and colored aluminum pigments based on inorganic coatings, and any of them can be used.

D-5. Lubricant The colored resin film B preferably contains polytetrafluoroethylene and polyethylene wax. Polyethylene wax having a molecular weight of 600 to 1200 and a melting point of 70 to 140 ° C. is used.
These lubricants b2 impart lubricity to the coating film surface and improve wear resistance.
It is preferable that the total content of the lubricant is 1% to 5%. If it is less than 1%, the lubricity is poor, the coating film is easily scratched, and the wear resistance is poor. If it exceeds 5%, foaming is severe in the state of the paint and cannot be made into a paint.

D-6. Glass beads By containing glass beads in the colored resin film B, the film becomes hard, so that the wear resistance can be further improved. It is preferable that the particle size and addition amount of the glass beads are in the same range as the resin film A.

D-7. Additives In addition, the coating material used in the present invention includes a leveling agent, an anti-waxing agent, a stabilizer, an anti-settling agent, etc. used in ordinary coating materials in order to ensure the paintability and general performance as a pre-coating material. You may add suitably.

D-8. Formation of colored resin film B A thermocoating resin, a pigment, and a lubricant as essential components, and the glass beads and additives are added as appropriate thereto, and a paint obtained by dissolving or dispersing them in a suitable solvent is formed by a roll coater. It is directly applied onto the substrate, treated for a predetermined time in an oven at a predetermined temperature, and baked and dried. Moreover, it may replace with a roll coater and may apply | coat directly on a chemical conversion film by an air spray, a bar coater, etc.

  Hereinafter, the present invention will be described in detail with reference to examples.

Invention Examples 1-20
An aluminum alloy plate was used as the metal plate. Both surfaces of an aluminum alloy plate (material: JIS A5182, plate thickness: 0.8 mm) were degreased with a commercially available aluminum degreasing agent, washed with water, and then subjected to chemical conversion treatment with a commercially available phosphoric acid chromate treatment solution. Next, paint A (using a polyester resin) shown in Table 1 was applied to one chemical conversion treated surface with a bar coater and baked. On top of this, paint B (using a polyester resin with an aluminum pigment added) was applied with a bar coater and baked. The baking temperature was a maximum plate temperature (PMT) of 230 ° C. Table 1 shows the production conditions of the samples of Invention Examples 1 to 20.

Comparative Examples 1-22
Samples of Comparative Examples 1 to 22 were produced based on the production conditions shown in Table 2 in the same manner as Invention Examples 1 to 20.

As a result of measuring the film amount of the chemical conversion film obtained by the above-described method using a fluorescent X-ray analyzer, the chromium amount was 30 mg / m ² .
About the precoat aluminum alloy plate sample produced in Invention Examples 1-22 and Comparative Examples 1-20, the density of the glass beads of the resin coating A and the colored resin coating B cross section, the dynamic friction coefficient of the colored resin coating B surface, the wear resistance, the bending Workability and pencil scratch value were evaluated by the following methods. ○, ○ △, and Δ were acceptable, and x was unacceptable.

<Density of glass beads>
The density of glass beads is determined by cutting a pre-coated aluminum alloy plate in a direction perpendicular to the coating direction, embedding in resin, polishing the cross section after curing, and observing with an optical microscope (100 times), and counting the number of glass beads. The number of glass beads per 5 mm was calculated.

<Dynamic friction coefficient>
The dynamic friction coefficient was measured using a Bowden friction test.

<Abrasion resistance>
Using an AIR-IN plastic eraser made by PLUS, the resin film was observed by reciprocating 2000 times under the condition of a load of 500 g / cm ² .
◯: No abnormality △: A trace of the colored resin film B is slightly peeled Δ: A colored resin film B is peeled off and the resin film A is exposed x: A trace of the resin film A is peeled off

<Bending workability>
Bending workability is in accordance with JIS Z2248. Bending is performed 180 degrees by sandwiching three base plates (total thickness 2.4 mm) with the coating surface of the pre-coated aluminum alloy plate on the outside. Observed.
○: No cracking of coating film ×: With cracking of coating film

<Pencil scratch value>
The pencil scratch value was measured according to JIS H4001. Judgment was carried out by scratch judgment.
○: 2H or more ×: H or less

  The test results of Invention Examples 1 to 20 and Comparative Examples 1 to 22 are shown in Tables 3 and 4.

  The coating surface of the precoated aluminum alloy plates of Invention Examples 1 to 8 has a resin coating A containing glass beads and a colored resin coating B thereon, and in the resin coating A, the particle size of the glass beads is 5 μm at the maximum major axis. -70 μm, the film thickness is in the range of 7-20 μm, the number of glass beads existing between 5 mm perpendicular to the coating direction is in the range of 15-150, and the colored resin film B The result of using a film having a dynamic friction coefficient of 0.03 to 0.20 is shown. With these precoated aluminum alloy plates, good wear resistance, bending workability, and pencil scratch value were obtained.

  The coating surfaces of the precoated aluminum alloy plates of Invention Examples 9 to 14 further show the results of using a coating containing glass beads in the colored resin coating B. With these precoated aluminum alloy plates, good wear resistance, bending workability, and pencil scratch value were obtained.

  The coating surface of the precoated aluminum alloy plates of Invention Examples 15 to 20 has a resin coating A and a colored resin coating B containing glass beads, and the particle size of the glass beads is in the range of 5 μm to 70 μm at the maximum major axis. The results are shown using a film having a thickness in the range of 7 μm to 20 μm and a number of glass beads in the range of 15 to 150 between 5 mm perpendicular to the coating direction. With these precoated aluminum alloy plates, good wear resistance, bending workability, and pencil scratch value were obtained.

  On the other hand, since the particle diameter of the glass bead contained in the resin film A is less than 5 micrometers, the comparative example 1 was inferior in abrasion resistance and a pencil scratch value.

  In Comparative Example 2, since the particle size of the glass beads contained in the resin film A exceeded 70 μm, the bending workability was inferior.

  In Comparative Example 3, since the film thickness of the resin film A was less than 7 μm, the wear resistance and the pencil scratch value were inferior.

  Since the film thickness of the resin film A exceeded 20 micrometers, the comparative example 4 was inferior in bending workability.

  In Comparative Example 5, since the density of the glass beads contained in the resin film A was less than 15 pieces / mm, the wear resistance and the pencil scratch value were inferior.

  In Comparative Example 6, since the density of the glass beads contained in the resin film A exceeded 150 / mm, the bending workability was inferior.

  Comparative Example 7 was inferior in wear resistance because the coefficient of dynamic friction on the surface of the colored resin film B exceeded 0.20.

  In Comparative Example 8, since the particle size of the glass beads contained in the colored resin film B was less than 5 μm, the wear resistance was inferior.

  In Comparative Example 9, since the particle size of the glass beads contained in the colored resin film B exceeded 70 μm, the bending workability was inferior.

  Since the film thickness of the colored resin film B is less than 7 micrometers, the comparative example 10 was inferior in abrasion resistance.

  In Comparative Example 11, since the film thickness of the colored resin film B exceeded 20 μm, the bending workability was inferior.

  Since the density of the glass bead contained in the colored resin film B is less than 15 pieces / mm, the comparative example 12 was inferior in abrasion resistance.

  Since the density of the glass bead contained in the colored resin film B exceeds 150 pieces / mm, the comparative example 13 was inferior in bending workability.

  In Comparative Example 14, since the particle size of the glass beads contained in the resin film A was less than 5 μm, the wear resistance was inferior.

  In Comparative Example 15, since the particle size of the glass beads contained in the resin film A exceeded 70 μm, the bending workability was inferior.

  In Comparative Example 16, since the film thickness of the resin film A was less than 7 μm, the wear resistance was inferior.

  In Comparative Example 17, since the film thickness of the resin film A exceeded 20 μm, the bending workability was inferior.

  Since the density of the glass bead contained in the resin film A is less than 15 pieces / mm, the comparative example 18 was inferior in abrasion resistance.

  Since the density of the glass bead contained in the resin film A exceeds 150 pieces / mm, the comparative example 19 was inferior in bending workability.

  In Comparative Examples 20 to 22, since glass beads were not added to the resin film A and the colored resin film B, the wear resistance and the pencil scratch value were inferior.

Claims (3)

In a pre-coated aluminum alloy plate having a chemical film formed on both surfaces of an aluminum alloy plate and a resin film A and a colored resin film B on at least one of the chemical films, the resin film A and the colored resin film B Or both contain 15 to 150 glass beads having a maximum major axis in the range of 5 μm to 70 μm in a direction perpendicular to the coating direction in a direction perpendicular to the coating direction of 5 mm to a thickness of 7 μm to 20 μm. A pre-coated aluminum alloy plate for a housing, characterized in that there is. When glass beads are contained in both the resin film A and the colored resin film B, the glass beads contained in the resin film B are in the range of 60 to 70 in a direction perpendicular to the coating direction at 5 mm. The precoated aluminum alloy plate for a casing according to claim 1, wherein The precoated aluminum alloy sheet for a casing according to claim 1 or 2, wherein the colored resin film B has a dynamic friction coefficient in a range of 0.03 to 0.20.