JP2008094085A - Precoated metal sheet excellent in blemish resistance and conductivity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precoated metal sheet which spreads as an object for drive cases of electric apparatuses or electronic instruments, excels in blemish resistance to optical discs and has conductivity. <P>SOLUTION: The precoated metal sheet comprises: chemical conversion coatings formed on both sides of a metal sheet; a polyester resin on one of the chemical conversion coatings; and a coated film A which includes at least one sort of base plastics a1 chosen from a group consisting of epoxy based plastics and acrylic plastics, a plastic bead a2, and graphite a3, wherein the dry film thickness β of the coated film A is in the range of 0.4 μm-4.0 μm, the arithmetical mean roughness Ra on a surface of the paint film is in a range of 0.3 μm-3.0 μm, and the concentration of the plastic beads a2 is in a range of 200-800 piece per 1 mm<SP>2</SP>of the coated film surface. To the opposite surface of the coated film A, a conductive resin film or a heat releasing and conductive resin film may be included. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scratch-resistant pre-coated metal plate used for casings of electrical equipment and electronic equipment such as liquid crystal televisions, personal computers, and DVD players.

  In recent years, the development of housings and optical discs for electrical and electronic devices has progressed, and slot-in type drive cases that enable further space saving of drive cases have begun to spread. The slot-in method is a function of automatically pulling an optical disk such as a CD-R or a DVD-R into the drive case by simply inserting it into the insertion slot while bare. Compared with the conventional tray system, it is not necessary to pull out the tray, so that the space can be saved, and the optical disk can be taken in and out smoothly, and the usability is improved.

  The slot-in method is more susceptible to scratches on the optical disc than the tray method. In the tray system, the optical disk is not easily damaged because it is inserted and removed while the optical disk is fixed on the drawn tray. In the slot-in method, the optical disk may be damaged when the optical disk is removed and inserted in the following cases. (1) The distance between the optical disk and the inner surface of the drive case is narrow, and the optical disk and the inner surface of the drive case collide due to the thickness accuracy of the optical disk itself or bending during operation of the optical disk. (2) The case where the optical disk and the inner surface of the drive case come into contact with each other when an unexpected impact is applied to the drive during reproduction or recording of the optical disk. (3) The optical disc may be tilted depending on the inserted state, and the optical disc and the inner surface of the drive case are in contact with each other. There are various structures on the inner surface of the drive case, but the portion of the inner surface of the drive case that may be in contact with the optical disk is a flat surface because it is a flat surface.

Various types of optical discs have been developed. Even if the surface of the optical disc is slightly scratched, there are some that adversely affect the reproduction and writing of the recording. For this reason, if the optical disk is damaged due to contact between the optical disk and the inner surface of the drive case, the optical disk cannot be used.
In order to prevent such scratches, the present inventors have intensively studied and have completed the invention described in Non-Patent Document 1 in the past.
Japanese Patent Application No. 2005-337490

  However, depending on the structure of the inner surface of the drive case, there has been a case where the coating film is required to have electrical conductivity for ground connection necessary for preventing electrostatic charging that causes malfunction of the electronic device. Since the coating material disclosed in Non-Patent Document 1 does not contain a conductive substance, there is a disadvantage that the necessary conductivity cannot be secured on the inner surface of the drive case.

  An object of the present invention is to provide a pre-coated metal plate that is widely used as a drive case for electrical equipment and electronic equipment, and has excellent scratch resistance, electrical conductivity, and molding processability for an optical disk.

In order to solve the above problems, the present invention has the following configuration.
That is, as defined in claim 1, a chemical conversion film formed on both surfaces of a metal plate, and at least one selected from the group consisting of a polyester resin, an epoxy resin, and an acrylic resin on one of the chemical conversion films The base resin a1 is provided with a coating film A containing resin beads a2 and graphite a3, the dry coating thickness β of the coating film A is in the range of 0.4 μm to 4.0 μm, and the arithmetic average roughness of the coating film surface Ra is in the range of 0.3 μm to 3.0 μm, and the density of the resin beads a2 is in the range of 200 to 800 per 1 mm ^{2 of the} coating film surface. Excellent scratch resistance and conductivity It is a precoat metal plate.

The invention according to claim 2 is that on the surface of the metal plate, a protrusion having an arithmetic average roughness Ra ′ (μm) or more on a straight line passing through a protrusion having a maximum height in a predetermined range and orthogonal to the rolling direction is 1 mm ^2. The precoated metal plate having excellent scratch resistance and conductivity according to claim 1, wherein 19 to 868 are present per unit.

  In the invention of claim 3, the average particle size Pd of the resin beads a2 is in the range of 2 μm to 20 μm, and further comprises a lubricating resin film D on the coating film A, and the film thickness of the lubricating resin film D is The scratch resistance and electrical conductivity according to claim 1, wherein α is in the range of 0.1 μm to 1.0 μm and Pd / (α + β) is in the range of 1.3 to 3.3. It is a precoated metal plate with excellent properties.

  The invention of claim 4 is one or two selected from the group consisting of a polyester resin, an epoxy resin and an acrylic resin on the chemical conversion film on the surface opposite to the surface on which the coating film A is formed. One or more selected from the group consisting of polyethylene wax, carnauba wax and microcrystalline wax, in which Ni filler b2 is mixed with the above base resin b1 in a weight ratio of 10 to 70% with respect to the resin solid content. It further comprises a conductive resin film B coated with 0.2 to 2.0 μm of a paint obtained by mixing 1 to 5% of the lubricant b3 in a weight ratio to the resin solid content as a dry film thickness. The precoated metal sheet having excellent scratch resistance and conductivity according to any one of Items 1 to 3.

  Furthermore, the invention of claim 5 is a group consisting of a fluorine-based resin, an epoxy-based resin, a polyester-based resin, an acrylic resin, and a urethane-based resin on the chemical conversion film on the surface opposite to the surface on which the coating film A is formed. A heat-dissipating and conductive resin film C containing one or more base resins c1 selected from the above, a heat-dissipating material c2 containing at least graphite, and a conductive material c3 containing at least Ni filler is further provided. It is a precoat metal plate excellent in the flaw resistance and electroconductivity as described in any one of Claims 1-3 characterized by the above-mentioned.

  The precoated metal sheet of the present invention contains resin beads in the coating film, the resin beads density on the coating film surface is set within a predetermined range, and the arithmetic average roughness of the coating film surface is set within a predetermined range. Since the contact area between the film surface and the optical disk can be kept small, the scratch resistance can be improved.

  The pre-coated metal sheet of the present invention can reduce electrical resistance by containing graphite in the coating film and setting the dry coating film thickness within a predetermined range. Moreover, since lubricity can be provided to the coating film surface, molding processability can be improved.

  Furthermore, by setting the number of protrusions having an arithmetic average roughness Ra ′ (μm) or more on the surface of the metal plate within a predetermined range, the scratch resistance and adhesion of the coating film A can be improved, and pre-coating can be performed. The appearance of the metal plate is also excellent. Furthermore, the average particle diameter of the resin beads a2 is set within a predetermined range, and the lubricating resin film D is further provided on the coating film A. The film thickness α of the lubricating resin film D is set within the predetermined range, and Pd / By setting (α + β) within a predetermined range, it is possible to prevent the resin beads a2 from falling off. As a result, the scratch resistance can be further improved. Here, β is the thickness of the coating film A limited to a predetermined range.

  Furthermore, since the predetermined conductive resin film B is provided on the surface of the metal plate opposite to the coating film A, the outer surface of the drive case can be electromagnetically shielded or grounded.

  In still another embodiment, since the resin film C having a predetermined electrical resistance and the drive case surface temperature is provided on the surface of the metal plate opposite to the coating film A, the outer surface of the drive case is electromagnetically shielded or grounded. It can be grounded and the amount of heat trapped inside the drive case can be reduced.

A. Metal plate The metal used in the present invention is particularly limited as long as it has sufficient strength to form a drive case for parts of electric equipment and electronic equipment and has sufficient formability. However, pure aluminum, aluminum alloy such as 5000 series aluminum alloy, galvanized steel, stainless steel, hot dip galvanized steel, hot dip galvanized aluminum alloy steel are preferred.

In the present invention, on the surface of the metal plate, protrusions having an arithmetic average roughness Ra ′ (μm) or more on one straight line passing through the protrusions having the maximum height in a predetermined range and orthogonal to the rolling direction per 1 mm ² There are preferably 19 to 868. When the number of protrusions is less than 19, the anchor effect is not sufficiently exhibited even if a chemical conversion film is formed as described later. As a result, the adhesion between the coating film A and the chemical conversion film becomes insufficient, and the scratch resistance and the adhesion after bending are inferior. On the other hand, if the number of protrusions exceeds 868, the metal plate surface tends to break, and the appearance of the bent part is inferior.

In practicing the present invention, the surface shape of the metal plate can be measured, for example, using a confocal microscope HD100 manufactured by Lasertec Corporation. A three-dimensional image of the surface of a metal plate is measured with an objective lens 50 times, passes through the highest protrusion existing in an arbitrarily selected 322 μm square area, and is a straight line in a direction perpendicular to the rolling direction of the metal plate The roughness of each protrusion existing above is measured, and the arithmetic average value of these roughnesses is defined as the arithmetic average roughness Ra ′ (μm). Then, for a given area of 322μm angle described above to give a 3-dimensional image consisting of only the protruding portion having a Ra 'more height, measured the number of protrusions present in the image, which 1 mm ² per Convert to the number of items. At this time, the filter size of the median filter is set to 5 * 5. That is, a predetermined area of 322 μm square is arbitrarily selected at five locations, and such measurement is performed at each location to determine the number of protrusions of Ra ′ or more per 1 mm ² . Finally, the arithmetic average value of the number of protrusions at five locations is defined as the number of protrusions having a height equal to or higher than Ra ′. The measurement area is not limited to 322 μm square, and can be any area. Moreover, you may obtain | require the number of protrusion parts more than arithmetic mean roughness Ra 'with another measuring method.

In order to set the number of protrusions with an arithmetic average roughness Ra ′ or more to 19 to 868 per mm ^{2 on the} surface of the metal plate, the surface shape of the rolling roll, the rolling speed, and the viscosity of the lubricating oil for rolling are appropriately adjusted. There is a need to. This is because the surface shape of the rolling roll is transferred to the metal plate during rolling, and oil pits are formed on the surface of the metal plate. The surface shape of the metal plate is mainly affected by the surface shape of the rolling roll, the shape of the oil pit, and the distribution state. Examples of the method for adjusting the uneven shape of the rolling roll include polishing or shot blasting, electric discharge machining, and laser machining. The arithmetic average roughness Ra ′ is preferably in the range of 0.1 to 0.6 μm.

B. Chemical conversion film The chemical conversion film is not particularly limited as long as it is interposed between the surface of the metal 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 liquid on the aluminum alloy plate or immersing the alloy plate in the treatment liquid at a predetermined temperature for a predetermined time. For galvanized steel and stainless steel, a conversion coating formed with a phosphating solution can be used in addition to the chromate treatment.

  Before the chemical conversion treatment, in order to remove dirt on the surface of the metal plate or to adjust the surface properties, the metal plate is subjected to acid treatment (washing) with sulfuric acid, nitric acid, phosphoric acid, etc., or caustic soda, It is desirable to perform alkali treatment (washing) with sodium phosphate, sodium silicate, or the like. Surface treatment by such cleaning is also performed by spraying a predetermined surface treatment liquid on the metal plate or immersing the metal plate in the treatment liquid at a predetermined temperature for a predetermined time.

C. Coating A
Subsequently, the coating film A is formed on the chemical conversion film. The coating film A is formed by baking and painting a base resin, resin beads, and further containing graphite as essential components and dissolving or dispersing them in a suitable solvent.

C-1. Dry coating thickness β of coating A
The dry coating film thickness β of the coating film A was set to 0.4 to 4.0 μm in a portion where no resin beads were present. If it is less than 0.4 μm, the graphite aggregates present in the vicinity of the resin beads come into contact with the optical disk, so that the scratch resistance is poor. On the other hand, if it exceeds 4.0 μm, the electrical resistance value becomes large and the conductivity is inferior.

C-2. Arithmetic average roughness Ra of coating film A
The arithmetic average roughness Ra of the coating film A was set to 0.3 μm to 3.0 μm. If it is less than 0.3 μm, the contact area between the coating film surface and the optical disk tends to be large, so that the scratch resistance is poor. On the other hand, when it exceeds 3.0 μm, the coating film at the bent portion is easily broken, and the bending workability is inferior.

C-3. Density of resin beads The density of resin beads was set to 200 to 800 per 1 mm ^{2 of} the coating film surface. Since resin beads are contained in the coating film, there are convex portions on the surface of the coating film. As described above, since the optical disk and the coating film surface are in surface contact, the distribution of the convex portions affects the contact area between the optical disk and the coating film surface. When the number is less than 200, a portion different from the convex portion also comes into contact with each other, and the contact area between the coating film surface and the optical disk tends to be large, so that the scratch resistance is poor. On the other hand, if the number exceeds 800, the convex portions are excessively present, so that the contact area between the coating surface and the optical disk tends to be large, and the scratch resistance is poor. Further, since the convex portion is the starting point during bending, the coating film of the bending portion is easily broken, and the bending workability is inferior.

C-4. Base resin a1
As the base resin a1, at least one selected from the group consisting of polyester resins, epoxy resins, and acrylic resins, that is, one or more of these resins is used. These resins can reduce the deformation of the coating film when the contact object such as an optical disk and the coating film are in contact with each other, reduce the contact area between the coating film and the contact object such as the optical disk, and improve the scratch resistance. it can.

  As the polyester resin, alkyd resin, unsaturated polyester resin, modified alkyd resin and the like are used. The alkyd resin has a skeleton of a condensate of a polybasic acid such as phthalic anhydride and a polyhydric alcohol such as glycerin, which is modified with fatty acid fats and oils. Depending on the type and content of the fats and oils used, the oils are classified into short oil alkyd resins, medium oil alkyd resins, long oil alkyd resins and super long oil alkyd resins. An unsaturated polyester resin is synthesized by esterifying an unsaturated polybasic acid or a saturated polybasic acid and a glycol. As the polybasic acid, phthalic anhydride, isophthalic acid, terephthalic acid and adipic acid are used, and as the glycols, propylene glycol is often used. As the modified alkyd resin, those modified with a polymerizable monomer such as natural resin, phenol resin or styrene are used.

  As the epoxy resin, bisphenol A type epoxy resin, acrylic modified epoxy resin, bisphenol F type epoxy resin, or the like can be used.

  As an acrylic resin, what is obtained by superposing | polymerizing 1 type (s) or 2 or more types of monomers, such as acrylic acid, methacrylic acid, methyl methacrylate, and ethyl acrylate, can be used.

  It is preferable to use a polyester-based 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.

C-5. Resin beads a2
By containing the resin beads a2 in the coating film A, the resin beads a2 are elastically deformed when the optical disk comes into contact with each other, and a buffering effect that reduces the impact caused by the contact is exhibited. Thereby, the damage resistance with respect to to-be-contacted objects, such as an optical disk, improves.

  Since such resin beads a2 protrude upward from the coating film surface, the contact area between the contacted object such as an optical disk and the coating film surface can be reduced. As a result, the slipperiness when the optical disk comes into contact with the coating film surface is improved, and the scratch resistance to the optical disk can be improved. However, even if acrylic beads having high hardness are added, the optical disk is scratched and becomes a problem. In contrast, by including one or two or more resin beads selected from the group consisting of nylon resin beads and fluorine resin beads rich in lubricity, and urethane resin beads rich in flexibility, Sufficient scratch resistance can be obtained. Among these, it is preferable to use fluorine resin beads or urethane resin beads.

  Urethane resin beads include those obtained by polyaddition reaction of diisocyanate and glycol, those obtained by allowing bischloroformate of glycol to act on diamine in the presence of a dehydrochlorinating agent, and diamine and ethylene carbonate. Those obtained by the reaction, those obtained by condensing the ω-aminoalcohol with a chloroformate or carbamic acid ester, and those obtained by the reaction of bisurethane and diamine are used. Many of those obtained by polyaddition reaction of diisocyanate and glycol are used. As diisocyanate, tolylene diisocyanate (a mixture of 2,4- and 2,6-) is often used and has a hydroxyl group. As the compound, ether-based compounds such as polyoxypropylene glycol and polyoxypropylene-polyoxyethylene glycol, and polyester-based compounds obtained by condensing adipic acid and ethylene glycol are often used.

  Examples of nylon resin beads include 6-nylon, 6,6-nylon, 3-nylon, 4-nylon, 7-nylon, 11-nylon, 12-nylon, 6,10-nylon, 6,12-nylon, etc. Beads are used. Of these, 6-nylon, 6,6-nylon, and 6,10-nylon are preferably used.

  Fluorine resin beads include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (PEP), and polychlorotrifluoroethylene. (PCTFE), ethylene / tetrafluoroethylene copolymer (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polytrifluorochloroethylene Beads such as (PTFCE) and polydichlorodifluoroethylene (DCDFE) are used. Of these resins, polytetrafluoroethylene (PTFE) is most preferably used.

  The average particle diameter of the resin beads a2 to be used is preferably 2 to 20 μm. If the average particle size is less than 2 μm, the contact area with the optical disk cannot be reduced, and the optical disk is easily damaged. On the other hand, if it exceeds 20 μm, the resin beads easily fall off from the coating film during the molding process, and the optical disk is easily damaged when used.

  The content of the resin beads a2 is preferably 3 to 20% by weight ratio with respect to the resin solid content of the coating film. If it is less than 3%, the contacted object easily comes into contact with the surface of the coating film where the resin beads a2 are not present, and the optical disk is easily damaged. On the other hand, if it exceeds 20%, the resin beads are easily removed from the coating film during the molding process, and the optical disk is easily damaged.

C-6. Graphite a3
By making the coating film A contain graphite a3, conductivity can be imparted. Artificial graphite and natural graphite can be used as the graphite a3. Artificial graphite is baked at about 1000 ° C. after adding pitch as a binder to petroleum-based or coal-based coke, kneading and molding. Next, the fired body was directly energized, graphitized at about 3000 ° C. using self-heating, and pulverized. Natural graphite is produced as scaly graphite or scaly graphite having high crystallinity, and earthy graphite having slightly low crystallinity. The produced ore is pulverized as it is, or fixed carbon is made 75% or more by flotation. Graphite has an Sp ² hybrid orbital and forms a hexagonal network plane by three σ bonds, and the remaining one electron is oriented perpendicular to the network plane and is called a π bond. π electrons move like free electrons in the hexagonal network. Therefore, graphite has high conductivity. Moreover, since the hexagonal mesh surfaces of carbon atoms are stacked and connected only by a distance of 3.354 km with a van der Waals force, the bonding force between the mesh surfaces is weak and exhibits self-lubricating properties. Therefore, lubricity can be imparted to the coating film surface, and molding processability can be improved.

  The average particle size of graphite is preferably 4 μm or less. Graphite may agglomerate during the preparation of the paint. If the particle size of the aggregate is larger than the particle size of the resin beads, the graphite protrudes on the surface of the coating and is easily damaged when it comes into contact with the optical disk. If the average particle diameter of the graphite exceeds 4 μm, the graphite aggregates during the preparation of the paint and the scratch resistance is poor.

  The content of graphite is preferably 10 to 80% by weight ratio to the resin solid content of the coating film. If it is less than 10%, the conductivity is inferior, and if it exceeds 80%, the coating film becomes brittle and the bending workability is inferior.

C-7. 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.

  Furthermore, it is preferable to add a lubricant to the paint used in the present invention. The lubricant is preferably one or more selected from the group consisting of carnauba wax, polyethylene wax and microcrystalline wax. Carnauba wax is a plant wax mainly composed of a higher fatty acid ester and has a melting point of 78 to 86 ° C. A polyethylene wax having a molecular weight of 600 to 12000 and a melting point of 70 to 140 ° C. is used. The microcrystalline wax is a fine wax of crystallinity obtained from petroleum components and has a melting point higher than that of paraffin. For example, a wax having a molecular weight of 600 to 900 and a melting point of 60 to 100 ° C. is used.

  These lubricants impart lubricity to the coating surface during molding such as press molding, improve the scratch resistance of the coating, and also impart lubricity to the coating surface after molding. , Has the effect of reducing the frictional force generated between the optical disk and the coating surface.

  The content of the lubricant is preferably 0.2 to 10% by weight ratio with respect to the resin solid content, and more preferably 0.2 to 3%. If it is less than 0.2%, sufficient lubricity cannot be imparted to the surface of the coating film, the coating film is likely to be damaged during press molding, and the optical disk is likely to be damaged. This is because if the content of the lubricant exceeds 10%, the lubricant slips during coil-up when the precoated metal plate is manufactured, and winding becomes difficult.

C-8. Coating film formation Base resin a1, resin bead a2 and graphite a3 are essential components, and the above additives are added appropriately to this, and a paint in which these are dissolved or dispersed in an appropriate solvent is directly applied onto the chemical conversion film by a roll coater. Then, it is baked and dried in a predetermined temperature oven for a predetermined time. The content of the base resin a1 in the paint is preferably 5 to 40% by weight. Solvents include benzene, toluene, methyl alcohol, ethyl alcohol, ethyl acetate, butyl acetate, cellosolve, butyl cellosolve, 1,4-dioxane, tetrahydrofuran, cyclohexane, isophorone, isobutyl alcohol, xylene, ethylbenzene, methyl ethyl ketone, diacetone alcohol, ethylene Glycol monobutyl ether or the like is used. In addition, it may replace with a roll coater and may apply | coat a coating material with an air spray, a bar coater, etc.

C-9. Conductivity The conductivity of the coating film A is 10 Ω or less when a silver probe (using a 5 mm diameter, 2.5 mmR tip) is contacted with a load of 500 g by the four-terminal method. Is preferred. This is because if it exceeds 10Ω, sufficient electric characteristics required for the inner surface of the drive case cannot be secured.

F. Lubricating resin film D
A lubricating resin film D may be further formed on the coating film A. The lubricating resin film D is formed by baking and painting a paint containing a base resin d1 and a lubricant d2 as essential components and dissolving or dispersing them in an appropriate solvent.

F-1. Base resin d1
As the base resin d1, at least one selected from the group consisting of polyester resins, epoxy resins, and acrylic resins, that is, one or more of these resins is used. These resins exhibit an effect of reducing deformation of the resin film D when the resin film D comes into contact with a contacted object such as an optical disk. As a result, the contact area between the resin film D and the contacted object such as an optical disk can be reduced, and the scratch resistance of the precoated metal plate can be improved.
As specific examples of the polyester resin, epoxy resin, and acrylic resin used as the base resin d1, the same resin as the base resin a1 can be used.

F-2. Lubricant d2
As the lubricant b2, one or more selected from the group consisting of carnauba wax, polyethylene wax and microcrystalline wax are used. These waxes are the same as those added to the coating film A.

These lubricants d2 impart lubricity to the surface of the resin film during molding such as press molding, improve the scratch resistance of the resin film D, and also lubricate the surface of the resin film D after molding. And has the effect of reducing the frictional force generated between the optical disk and the surface of the resin film D.
The content of the lubricant d2 is preferably 1 to 5% by weight ratio to the resin solid content of the base resin d1. If it is less than 1%, sufficient lubricity cannot be imparted to the surface of the resin film D, the resin film is easily damaged during press molding, and the optical disk is easily damaged. This is because if the content of the lubricant d2 exceeds 5%, the lubricant d2 slips during coil-up when the precoated metal plate is manufactured, and winding becomes difficult.

F-3. Film thickness α
The film thickness α of the lubricating resin film D is preferably 0.1 μm to 1.0 μm. When the thickness is less than 0.1 μm, almost no change is observed in the increase in the amount of the lubricating resin film D present around the resin beads a2, and thus the effect of improving the scratch resistance is not recognized. When the thickness exceeds 1.0 μm, the amount of graphite protruding from the lubricating resin film D in the graphite contained in the coating film A decreases, and therefore the conductivity is inferior.

F-4. Pd / (α + β)
If the amount of the resin component present around the resin beads a2 in the coating film is small, the resin beads a2 are likely to drop off. By forming the lubricating resin film D on the coating film A, the resin beads a2 can be prevented from falling off when the surface of the precoated metal plate and the optical disk come into contact with each other, and as a result, the scratch resistance can be improved. Can do. It is effective for scratch resistance that the surface shape of the pre-coated metal plate is appropriately adjusted. For that purpose, it is preferable to set Pd / (α + β) to 1.3 to 3.3. When this value is less than 1.3, the ratio of Pd to the sum of the thickness β of the coating film A and the thickness α of the lubricating resin film D is too small, that is, the unevenness on the surface of the precoated metal plate is small. Become. As a result, the scratch resistance of the precoated metal sheet is poor. On the other hand, if it exceeds 3.3, the ratio of Pd to the sum of α and β increases, that is, the amount of resin components formed by the base resins a1 and d1 existing around the resin beads a2 becomes insufficient, and the resistance The effect of improving scratchability cannot be obtained.

F-5. Additives In addition, the paint for the lubricating resin film D used in the present invention includes a pigment, a pigment dispersant, and a fluidity modifier that are used in ordinary paints to ensure paintability and general performance as a precoat material. , Leveling agents, anti-bacterial agents, preservatives, stabilizers and the like may be added as appropriate.

F-6. Resin film formation Base resin d1 and lubricant d2 are essential components, and the above additives are added thereto as appropriate, and a paint in which these are dissolved or dispersed in an appropriate solvent is directly applied onto coating film A by a roll coater. It is baked and dried after being treated in a temperature oven for a predetermined time. The concentration of the base resin d1 in the paint is preferably 5 to 40% by weight. As the solvent, the same solvent as used for the coating film A can be used. In addition, it may replace with a roll coater and may apply | coat a coating material with an air spray, a bar coater, etc.

F-7. Conductivity Since the graphite a3 contained in the coating film A protrudes from the surface of the lubricating resin film D, conductivity is imparted to the lubricating resin film D as a result. This conductivity is preferably set to 10Ω or less as an electric resistance value when a silver probe (having a diameter of 5 mm and a tip of 2.5 mmR) is brought into contact with a load of 500 g by a four-terminal method. This is because if it exceeds 10Ω, sufficient electric characteristics required for the inner surface of the drive case cannot be secured.

D. Conductive resin film B
It is good also as a precoat metal plate of the structure which further provided the electroconductive resin film B in the surface which becomes an outer surface of a drive case after shaping | molding, and is on the outer surface opposite side to the said coating film. In this case, a chemical conversion film is provided on the metal plate that is the outer surface opposite to the coating film A, and the conductive resin film B is formed thereon. As the conductive resin film B, a film formed by applying a paint in which an Ni resin and a wax are mixed with an organic resin as disclosed in Patent Document 1 can be used.
JP 2001-29885 A

D-1. Film thickness The dry coating film thickness of the conductive resin film B is 0.2 to 2.0 μm. If it is less than 0.2 μm, the conductivity is good, but the corrosion resistance and moldability are poor. When it exceeds 2.0 μm, the Ni filler is less exposed and the conductivity is inferior.

D-2. Base resin b1
As the base resin b1 used for the conductive resin film B, one or more selected from the group consisting of a polyester resin, an acrylic resin, or an epoxy resin is used. As the polyester resin, alkyd resin, unsaturated polyester resin, modified alkyd resin, and the like can be used. As acrylic resin, what is obtained by superposing | polymerizing 1 type (s) or 2 or more types of monomers, such as acrylic acid, methacrylic acid, methyl methacrylate, and ethyl acrylate, can be used. As the epoxy resin, bisphenol A type epoxy resin, acrylic modified epoxy resin, bisphenol F type epoxy resin, or the like can be used.

D-3. Ni filler b2
The Ni (nickel) filler b2 used for the conductive resin film B is a mixture of both a scaly Ni filler and a chain Ni filler. By mixing and using these Ni fillers, both conductivity and formability can be achieved.

  Usually, press oil is used during press molding. When press oil is interposed between the pre-coated metal plate and the mold, molding can be performed without any problem. However, when the lubricating film is locally cut, a scratch is generated on the surface of the pre-coated metal plate. Further, the Ni filler protrudes from the surface of the coating film, and when the lubricating film is cut off, the Ni filler may come off due to contact with the mold, and the appearance after molding may be deteriorated. In other words, it is important to keep the press oil on the surface of the pre-coated metal plate. By using a mixture of the two types of Ni fillers described above, the roughness of the coating film surface is moderately adjusted and the press oil is kept. be able to.

  The scaly Ni filler and the chain Ni filler are mixed in a weight ratio of 10 to 70% with respect to the resin solid content. If it is less than 10%, the conductivity and moldability are inferior. If it exceeds 70%, the electrical conductivity is good, but the moldability, adhesion and corrosion resistance are poor.

D-4. Lubricant b3
As the lubricant b3 used for the conductive resin film B, one or more lubricants selected from the group consisting of carnauba wax, polyethylene wax, and microcrystalline wax are used. Carnauba wax is a plant wax mainly composed of a higher fatty acid ester and has a melting point of 78 to 86 ° C. A polyethylene wax having a molecular weight of 600 to 12000 and a melting point of 70 to 140 ° C. is used. The microcrystalline wax is a fine wax of crystallinity obtained from a petroleum component and has a melting point higher than that of paraffin. For example, a wax having a molecular weight of 600 to 900 and a melting point of 60 to 100 ° C. is used.

  These lubricants b3 impart lubricity to the coating film surface during molding such as press molding, and improve the scratch resistance of the coating film.

  Lubricant b3 is mixed by 1 to 5% by weight with respect to the resin solid content. If it is less than 1%, the lubricity is inferior and the coating film is likely to be scratched. If it exceeds 5%, the lubricity is too good and it becomes a bowl and cannot be coiled up.

D-5. 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-6. Conductive resin film B formation Base resin b1, Ni filler b2, and lubricant b3 are essential components, and the above additives are appropriately added thereto, and a paint obtained by dissolving or dispersing them in an appropriate solvent is applied onto the chemical film by a roll coater. It is applied directly to the substrate, processed in an oven at a predetermined temperature for a predetermined time, and baked and dried. In addition, a top feed system in which a coating material supplied from above between a pickup roll and an applicator roll is roll-coated on a metal plate with an applicator roll is preferable. Instead of the roll coater, it may be applied directly on the chemical conversion film by air spray, bar coater or the like. The concentration of the base resin b1 in the paint is preferably 5 to 40% by weight. In addition, you may use the thing similar to using for the coating film A and the lubricous resin film D as a solvent of a coating material.

D-7. Conductivity The conductivity of the conductive resin film B is 10 Ω or less when a silver probe (with a diameter of 5 mm and a tip of 2.5 mmR) is contacted with a load of 100 g by the four-terminal method. To do. This is because if it exceeds 10Ω, sufficient electrical characteristics such as grounding and magnetic shielding required for the outer surface of the drive case cannot be secured.

E. Conductive and heat-dissipating resin film C
As a pre-coated metal plate having a structure in which a conductive and heat-dissipating resin film C is provided on the outer surface opposite to the coating film, instead of the conductive resin film B, on the outer surface of the drive case after molding. Also good. In this case, a chemical conversion film is provided on a metal plate on the outer surface opposite to the coating film, and a resin film having both conductivity and heat dissipation is formed thereon.

  Such a resin film C has one or two or more selected from the group consisting of a fluorine resin, an epoxy resin, a polyester resin, an acrylic resin, and a urethane resin as a base resin c1, and imparts heat dissipation. Therefore, at least graphite is contained, and at least Ni (nickel) filler is contained to impart conductivity. The polyester resin, acrylic resin, and epoxy resin as the base resin c1 are the same as the base resin a1 used for the coating film A. Moreover, the same resin as the resin bead a2 used for the coating film A is used as the fluorine resin and the urethane resin as the base resin c1.

  The conductivity imparting component such as Ni filler is mixed by 10 to 70% by weight with respect to the resin solid content. If it is less than 10%, the conductivity and moldability are poor, and if it exceeds 70%, the conductivity is good, but the moldability, adhesion, and corrosion resistance are poor. On the other hand, heat dissipation imparting components such as graphite are mixed in a weight ratio of 20 to 100% with respect to the resin solid content. If it is less than 20%, the heat dissipation is inferior, and if it exceeds 100%, the heat dissipation is good, but the moldability is inferior.

  The thickness of the conductive and heat-dissipating resin film C is preferably 0.3 to 5 μm in terms of the dry film thickness.

The conductivity of the conductive and heat-dissipating resin film C is 10Ω when a silver probe (using a 5 mm diameter, 2.5 mmR tip) is brought into contact with a load of 100 g by the four-terminal method. The following is preferable. This is because if it exceeds 10Ω, sufficient electrical characteristics such as grounding and magnetic shielding required for the outer surface of the drive case cannot be secured.
The heat dissipation of the conductive and heat-dissipating resin film C is as follows: the temperature of the drive case surface at the time when the temperature inside the drive case reaches a steady state by arranging a light source inside the drive case to emit light and generate heat. It shall be 32 degrees C or less. When the surface temperature of the drive case exceeds 32 ° C., heat accumulates in the drive case, which may impair the original performance of the electronic device.

For such a conductive and heat-dissipating resin film C, for example, a coating film formed by coating a paint in which graphite and Ni filler are mixed with an organic resin as disclosed in Patent Document 2 is used. Can do.
JP 2005-305993 A

  The scratch-resistant pre-coated metal plate described in detail above is preferably used as a drive case for electric devices and electronic devices such as televisions, video devices, personal computers, etc., but is not limited thereto, and is a structural drive. It can also be used for cases and the like. Further, although it has scratch resistance against optical disks such as CDs and DVDs, it is not limited to optical disks, but is used for scratch resistance to various members having a precise processed surface such as magnetic disks and magneto-optical disks. It may be used as

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

Invention Examples 1-9
An aluminum alloy plate was used as the metal plate. Both surfaces of an aluminum alloy plate (material: JIS A5052, plate thickness: 0.6 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, the coating b shown in Table 1 was applied to one chemical conversion treated surface B with a bar coater and baked. On the other hand, the other chemical conversion treatment surface (a) was coated with the paint a shown in Table 1 using a bar coater and baked to prepare a sample. The baking temperature of the paints b and a was a maximum plate temperature (PMT) of 230 ° C. Table 1 shows the production conditions of the samples of Invention Examples 1 to 9.

Comparative Examples 1-7
Samples of Comparative Examples 1 to 7 were produced based on the production conditions of Table 1 in the same manner as in Invention Examples 1 to 9.

Invention Examples 10 and 11
In Invention Example 10, a stainless steel plate was used as the metal plate, and in Invention Example 11, a galvanized steel plate was used as the metal plate. These metal plates were subjected to chemical conversion treatment with a commercially available chromate treatment solution. Next, a heat-dissipating and conductive resin coating composed of a polyester-based resin, graphite, and Ni filler was applied to one chemical conversion treated surface (b) with a bar coater so that the coating thickness after drying was 1 μm and baked. The content of graphite and Ni filler in the paint was 30% and 40% by weight ratio to the resin solid content.

  On the other hand, another chemical conversion treatment surface (a) was coated with a coating material a containing a base resin, resin beads and a lubricant shown in Table 2 with a bar coater and baked to prepare a sample. The baking temperature was a maximum plate temperature (PMT) of 230 ° C. Table 2 shows the production conditions of the samples of Invention Examples 10 and 11.

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 .

  For Invention Example 10 and Invention Example 11, a case was prepared by the following method, and the case surface temperature was measured. That is, a case with a bottom surface of 150 mm × 150 mm and a height of 100 mm was prepared with the front side of the pre-coated metal plate facing outward and the front surface facing inward, and a 60 W bulb was placed inside as a light source. The temperature on the surface of the housing was measured when the temperature inside the housing reached a steady state. As a result, the steady state temperature was 32 ° C.

  For the precoated metal sheet samples prepared in Invention Examples 1 to 11 and Comparative Examples 1 to 7, the arithmetic average roughness Ra of the coating film surface, the density of the resin beads on the coating film surface, scratch resistance, bending workability, conductivity and Corrosion resistance was evaluated by the following method. ○ and △ were accepted, and x was rejected.

<Arithmetic mean roughness Ra of coating surface>
The arithmetic average roughness Ra of the i-side of the precoated metal plate was measured according to JIS B0601.

<Density of resin beads on the coating surface>
The surface of the pre-coated metal plate was observed with an optical microscope (100 times), the number of resin beads was measured, and the number of resin beads in 1 mm ² was calculated.

<Scratch resistance>
The pre-coated metal plate was fixed on a surface plate with the surface of the pre-coated metal plate facing upward, and further, an optical disk and a weight were placed thereon, and the disk was slid horizontally to measure the maximum load at which the disk was not damaged. ○: 150 g or more Δ: 100 g or more and less than 150 g x: less than 100 g

<Bending workability>
Bending workability is in accordance with JIS Z2248. Bending is performed 180 degrees with three base plates sandwiched with the precoated metal plate facing out (total thickness 1.8mm), and the appearance of the bent portion is visually observed. did.
○: No cracking of coating film ×: Cracking of coating film

<Conductivity>
The electrical resistance value was measured when a silver probe (with a diameter of 5 mm and a tip of 2.5 mmR) was brought into contact with the surface of the pre-coated metal plate with a load of 500 g by the four-terminal method.
In addition, the electrical resistance value was measured when a silver probe (using a 5 mm diameter, 2.5 mmR tip) was brought into contact with the bottom surface of the precoated metal plate with a load of 100 g by the four-terminal method.
○: 10Ω or less ×: Over 10Ω

<Corrosion resistance>
A cross-cut was made on the surface of the pre-coated metal plate, a salt spray test was conducted for 100 hours, and the appearance was visually observed.
○: No corrosion ×: Corrosion

  Table 3 shows the test results of Invention Examples 1 to 11 and Comparative Examples 1 to 7.

The first surface of the precoated metal plates of Invention Examples 1 to 11 is a coating containing resin beads a2 and graphite a3 on at least one base resin a1 selected from the group consisting of polyester resins, epoxy resins and acrylic resins. A dry coating film thickness β of the coating film A is in the range of 0.4 μm to 4.0 μm, and the arithmetic average roughness Ra of the coating film surface is in the range of 0.3 μm to 3.0 μm. The result using the coating film in which the density of the resin beads a2 is in the range of 200 to 800 per 1 mm ^{2 of the} coating film surface is shown. With these pre-coated metal plates, good scratch resistance, conductivity and bending workability were obtained.

  The bottom surface of the pre-coated metal sheets of Invention Examples 1 to 9 is obtained by mixing 10 to 70% of Ni filler in a weight ratio with respect to the resin solid content in a base resin selected from polyester resin, epoxy resin, and acrylic resin. In addition, a coating obtained by mixing 1 to 5% of a lubricant selected from polyethylene wax, carnauba wax, and microcrystalline wax in a weight ratio with respect to the resin solid content was applied to a dry coating thickness of 0.2 to 2.0 μm. Since the resin film was provided, the corrosion resistance and conductivity were good.

  The bottom surface of the pre-coated metal plates of Invention Examples 10 to 11 is provided with a resin film containing a heat dissipation material of graphite and a conductive material of Ni filler on the base resin c1 of the polyester resin, so that the corrosion resistance and conductivity are good. It was.

On the other hand, in Comparative Example 1, the conductivity was inferior because graphite was not added to the coating film on the first surface of the precoated metal plate. Moreover, since content of Ni filler in the coating film of the front surface of a precoat metal plate exceeds 70% with respect to resin solid content, corrosion resistance was inferior.
Comparative Example 2 was inferior in scratch resistance because the thickness of the coating on the i-side of the pre-coated metal plate was less than 0.4 μm. Moreover, since the Ni filler was not contained in the coating film of the lower surface of a precoat metal plate, electroconductivity was inferior.
In Comparative Example 3, the conductivity of the pre-coated metal plate was inferior because the thickness of the coating on the first surface exceeded 4.0 μm. Moreover, since content of Ni filler in the coating film of the front surface of a precoat metal plate is less than 10% with respect to resin solid content, electroconductivity was inferior.
In Comparative Example 4, since the arithmetic average roughness of the i-side of the precoated metal sheet was less than 0.3 μm, the scratch resistance was inferior. Since the content of the Ni filler in the coating film on the lower surface of the pre-coated metal plate exceeds 70% with respect to the resin solid content, the corrosion resistance was inferior.
In Comparative Example 5, since the arithmetic average roughness of the i-side of the precoated metal sheet exceeded 3.0 μm, the bending workability was inferior. Moreover, since the thickness of the coating film of the surface of a precoat metal plate was less than 0.2 micrometer, corrosion resistance was inferior.
In Comparative Example 6, since the density of the resin beads on the first surface of the precoated metal plate was less than 200 pieces / mm ² , the scratch resistance was inferior. Moreover, since the thickness of the coating film on the lower surface of the pre-coated metal plate exceeded 2.0 μm, the conductivity was inferior.
Comparative Example 7 was inferior in scratch resistance and bending workability because the density of the resin beads on the surface of the pre-coated metal plate exceeded 800 pieces / mm ² . Moreover, since the coating thickness of the lower surface of a precoat metal plate exceeded 2.0 micrometers, electroconductivity was inferior.

Invention Examples 12-20, 27-30
An aluminum alloy plate was used as the metal plate. Both surfaces of an aluminum alloy plate (material: JIS A5052, plate thickness: 0.6 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. Subsequently, the coating material a shown in Table 4 was applied to one of the chemical conversion treated surfaces A by a bar coater and baked. On the other hand, another chemical conversion treatment surface (b) was coated with the coating b shown in Table 5 with a bar coater and baked to prepare a sample. The baking temperature of the coating material a and the coating material b was the maximum plate temperature (PMT) 230 ° C.

Table 6 shows the production conditions of the samples of Invention Examples 12-20 and 27-30. In addition, the surface roughness of the metal plate was measured using Lasertec Co., Ltd. confocal microscope HD100. Arithmetic that exists on a straight line passing through the maximum height protrusion and orthogonal to the rolling direction in a 322μm square area selected by measuring a three-dimensional image of the metal plate surface with an objective lens of 50x Average roughness Ra ′ was measured. A three-dimensional image including only protrusions having a height equal to or higher than Ra ′ was created in the above-described area portion of 322 μm square. At this time, the filter size of the median filter was set to 5 * 5. The number of protrusions present in the image was measured and converted to the number per 1 mm ² . Five measurement points were arbitrarily selected and measured five times, and an average value was calculated regarding Ra ′ and the number of protrusions per 1 mm ² .

Invention Examples 21-26, 31-32
An aluminum alloy plate was used as the metal plate. Aluminum alloy plate (Material: JIS
(A5052, plate thickness: 0.6 mm) Both surfaces were degreased using a commercially available alkaline degreasing solution, acid washed with dilute sulfuric acid, and then subjected to a chemical conversion treatment using a commercially available zirconium treating solution. Next, the coating material a shown in Table 4 was applied to one of the chemical conversion treated surfaces A by a bar coater and baked. Furthermore, the coating material d shown in Table 7 was applied and baked on the coating film A onto which the coating material a was baked with a bar coater. On the other hand, on the other chemical conversion treated surface (b), a paint b shown in Table 5 was applied with a bar coater and baked to prepare a sample. The baking temperatures of the paint a, the paint b, and the paint d were 230 ° C., the highest plate temperature (PMT). Table 6 shows sample preparation conditions of Invention Examples 21 to 26 and 31 to 32.

Invention Examples 33 to 34
In Invention Example 33, a galvanized steel sheet was used as the metal plate, and in Invention Example 34, a galvanized steel sheet was used as the metal plate. These metal plates were subjected to chemical conversion treatment with a commercially available chromate treatment solution. Next, a heat-dissipating and conductive resin coating composed of a polyester resin, graphite, and Ni filler was applied to one chemical conversion treated surface (b) with a bar coater so that the coating thickness after drying was 1 μm and baked. The content of graphite and Ni filler in the paint was 30% and 40% by weight ratio to the resin solid content.
On the other hand, another chemical conversion treatment surface (a) was coated with the paint a shown in Table 4 by a bar coater and baked to prepare a sample. The baking temperature was a maximum plate temperature (PMT) of 230 ° C. Table 8 shows the preparation conditions of the samples of Invention Examples 33 and 34.

Comparative Examples 8-13
Samples of Comparative Examples 8 to 13 were produced based on the production conditions shown in Table 6 in the same manner as Invention Examples 12 to 20 and 27 to 30.

In each invention example and comparative example, the amount of the chemical conversion film obtained by the above-described method was measured by a fluorescent X-ray analyzer, and as a result, the chromium amount was 30 mg / m ² and the zirconium amount was 10 mg / m ^2. It was.

  For Invention Example 33 and Invention Example 34, a case was produced by the following method, and the case surface temperature was measured. That is, a case with a bottom surface of 150 mm × 150 mm and a height of 100 mm was prepared with the front side of the pre-coated metal plate facing outward and the front surface facing inward, and a 60 W bulb was placed inside as a light source. The temperature on the surface of the housing was measured when the temperature inside the housing reached a steady state. As a result, the steady state temperature was 32 ° C.

  About the precoat metal plate sample produced in Invention Examples 12 to 34 and Comparative Examples 8 to 13, the arithmetic average roughness Ra of the coating film surface, the density of the resin beads on the coating film surface, the scratch resistance, the conductivity, and the corrosion resistance are invention examples. 1 to 11 and Comparative Examples 1 to 7 were tested and evaluated. In addition, about the bending workability, it evaluated by the following method and made (circle) and (triangle | delta) pass and x made it disqualified.

<Bending workability>
Bending workability is in accordance with JIS Z2248. Bending is performed 180 degrees with three base plates sandwiched with the precoated metal plate facing out (total thickness 1.8mm), and the appearance of the bent portion is visually observed. did. Thereafter, a tape peeling test was performed.
(A) Bending part appearance ○: No cracking of resin film ×: Cracking of resin film (b) Adhesiveness ○: No peeling of resin film ×: There is peeling of resin film

  The above evaluation results are shown in Table 9.

The first surface of the precoated metal plates of Invention Examples 12 to 20 and 33 to 34 is a chemical conversion film formed on both surfaces of a metal plate having 19 to 868 projections per 1 mm ² having an arithmetic average roughness Ra ′ or more. And coating film A containing resin beads a2 and graphite a3 on at least one base resin a1 selected from the group consisting of polyester resins, epoxy resins and acrylic resins on one of the chemical conversion films; Is provided. Here, the thickness β of the coating film A is in the range of 0.4 μm to 4.0 μm, the arithmetic average roughness Ra of the coating film surface is in the range of 0.3 μm to 3.0 μm, and the resin beads a2 The density is in the range of 200 to 800 per 1 mm ² of the coating surface. With these pre-coated metal plates, good scratch resistance, conductivity and bending workability were obtained.

The first surface of the precoated metal plates of Invention Examples 21 to 26 has a chemical conversion film formed on both surfaces of a metal plate having 19 to 868 projections per 1 mm ² having an arithmetic average roughness Ra ′ or more, and the chemical conversion film. On one of the films, at least one base resin a1 selected from the group consisting of a polyester resin, an epoxy resin, and an acrylic resin is provided with a coating film A containing resin beads a2 and graphite a3. Here, the thickness β of the coating film A is in the range of 0.4 μm to 4.0 μm, the arithmetic average roughness Ra of the coating film surface is in the range of 0.3 μm to 3.0 μm, and the resin beads a2 The density is in the range of 200 to 800 per 1 mm ² of the coating surface. And the average particle diameter of resin bead a2 exists in the range of 2-20 micrometers, and the lubricous resin film D is further provided on the coating film A, The film thickness (alpha) of this lubricous resin film D is 0.1-0.1. It exists in the range of 1.0 micrometer, Pd / ((alpha) + (beta)) exists in the range of 1.3-3.3. With these precoated metal sheets, good scratch resistance, electrical conductivity and bending workability were obtained, and in Examples 23 to 26, the scratch resistance was further improved.

  The bottom surface of the pre-coated metal plates of Invention Examples 12 to 26 is obtained by mixing 10 to 70% of Ni filler with a weight ratio to the resin solid content in a base resin selected from polyester resin, epoxy resin and acrylic resin. In addition, a coating obtained by mixing a lubricant selected from polyethylene wax, carnauba wax, and microcrystalline wax in a weight ratio of 1 to 5% with respect to the resin solid content was applied to a dry coating thickness of 0.2 to 2.0 μm. Since the conductive resin film B was provided, the corrosion resistance and conductivity were good.

  Since the bottom surface of the pre-coated metal plates of Invention Examples 33 to 34 is provided with a heat-dissipating and conductive resin film C containing a heat-dissipating material of graphite and a conductive material of Ni filler on the base resin c1 of the polyester resin, the corrosion resistance And the electrical conductivity was good.

The surface A of the pre-coated metal plates of Invention Examples 27 to 30 is selected from the group consisting of a chemical conversion film formed on both surfaces of the metal plate and a polyester resin, an epoxy resin and an acrylic resin on one of the chemical conversion films. At least one kind of base resin a1 is provided with a coating film A containing resin beads a2 and graphite a3. The first surface of the precoated metal plates of Invention Examples 31 to 32 further includes a lubricating resin film D on such a coating film A. Here, the thickness β of the coating film A is in the range of 0.4 μm to 4.0 μm, the arithmetic average roughness Ra of the coating film surface is in the range of 0.3 μm to 3.0 μm, and the resin beads a2 The density is in the range of 200 to 800 per 1 mm ² of the coating surface. In the precoated metal plates of Invention Examples 27 to 32, good scratch resistance, conductivity and bending workability were obtained.
However, in Invention Example 27, the number of protrusions of Ra ′ or more on the metal plate surface of the precoated metal plate was less than 19, so the scratch resistance and bending workability were slightly inferior. Since the content of the Ni filler in the resin film on the front surface of the pre-coated metal plate exceeds 70% with respect to the resin solid content, the corrosion resistance was inferior.
In Invention Example 28, since the number of protrusions of Ra ′ or more on the metal plate surface of the precoated metal plate exceeded 868, scratch resistance and bending workability (bending portion appearance) were slightly inferior. Moreover, since the film thickness of the surface of a precoat metal plate was less than 0.2 micrometer, corrosion resistance was inferior.
In Invention Example 29, since the average particle size of the resin heat on the i-side of the pre-coated metal sheet was less than 2 μm, the scratch resistance was slightly inferior. Moreover, since content of Ni filler in the resin film of the front surface of a precoat metal plate exceeds 70% with respect to resin solid content, corrosion resistance was inferior.
Invention Example 30 was slightly inferior in scratch resistance because the average particle diameter of the resin beads on the surface of the pre-coated metal plate exceeded 20 μm. Moreover, since the Ni filler was not contained in the resin film on the lower surface of the pre-coated metal plate, the conductivity was inferior.
Invention Example 31 was slightly inferior in scratch resistance and conductivity because the film thickness of the lubricating resin film on the i-side of the pre-coated metal plate exceeded 1.0 μm. Moreover, since the film thickness of the resin film in the 2nd surface of a precoat metal plate exceeds 2.0 micrometers, electroconductivity was inferior.
Invention Example 32 was slightly inferior in scratch resistance because Pd / (α + β) on the i-side of the precoated metal sheet was less than 1.3. Moreover, since the film thickness of the resin film in the 2nd surface of a precoat metal plate exceeds 2.0 micrometers, electroconductivity was inferior.

On the other hand, Comparative Example 8 was inferior in conductivity because graphite was not added to the resin film on the i-side of the pre-coated metal plate. Moreover, since content of Ni filler in the resin film of the front surface of a precoat metal plate exceeds 70% with respect to resin solid content, corrosion resistance was inferior.
In Comparative Example 9, the scratch resistance was inferior because the coating thickness on the i-side of the pre-coated metal plate was less than 0.4 μm. Moreover, since the Ni film | membrane was not contained in the resin film of the lower surface of a precoat metal plate, electroconductivity was inferior.
Comparative Example 10 was inferior in conductivity because the thickness of the coating on the i-side of the precoated metal plate exceeded 4.0 μm. Moreover, since content of Ni filler in the resin film of the front surface of a precoat metal plate is less than 10% with respect to resin solid content, electroconductivity was inferior.
In Comparative Example 11, since the density of the resin beads on the i-side of the pre-coated metal plate was less than 200 pieces / mm ² , the scratch resistance was inferior. Moreover, since the film thickness of the low surface of a precoat metal plate exceeded 2.0 micrometers, electroconductivity was inferior.
In Comparative Example 12, since the density of the resin beads on the i-side of the precoated metal plate exceeded 800 pieces / mm ² , the scratch resistance and bending workability (bending portion appearance) were inferior. Moreover, since the film thickness of the low surface of a precoat metal plate exceeded 2.0 micrometers, electroconductivity was inferior.
In Comparative Example 13, the density of the resin beads on the i-side of the precoated metal plate was 200 / mm ^2.
Therefore, the scratch resistance was inferior. Moreover, since the film thickness of the low surface of a precoat metal plate exceeded 2.0 micrometers, electroconductivity was inferior.

  According to the present invention, the coating film contains a base resin, resin beads and graphite, the coating thickness and the arithmetic mean roughness of the coating film surface are within a predetermined range, and the resin bead density is within a predetermined range, and the scratch resistance A precoated metal sheet excellent in conductivity and moldability is provided.

Claims (5)

A resin bead a2 and graphite on at least one base resin a1 selected from the group consisting of a chemical conversion film formed on both surfaces of a metal plate and a polyester resin, an epoxy resin and an acrylic resin on one of the chemical conversion films; a dry coating film thickness β of the coating film A is in the range of 0.4 μm to 4.0 μm, and the arithmetic average roughness Ra of the coating film surface is 0.3 μm to 3. A precoated metal sheet excellent in scratch resistance and conductivity, characterized in that it is in the range of 0 μm and the density of the resin beads a2 is in the range of 200 to 800 per 1 mm ^{2 of the} coating surface. On the surface of the metal plate, there are 19 to 868 protrusions per 1 mm ^{2 with} an arithmetic average roughness Ra ′ (μm) or more on one straight line passing through the protrusions of the maximum height in a predetermined range and orthogonal to the rolling direction. The precoated metal plate having excellent scratch resistance and conductivity according to claim 1.   The resin beads a2 have an average particle size Pd in the range of 2 μm to 20 μm, further provided with a lubricating resin film D on the coating film A, and a film thickness α of the lubricating resin film D of 0.1 μm to 1 The precoated metal sheet having excellent scratch resistance and electrical conductivity according to claim 1 or 2, wherein Pd / (α + β) is in the range of 1.3 to 3.3. .   One or more base resins b1 selected from the group consisting of a polyester resin, an epoxy resin, and an acrylic resin are formed on the chemical conversion film on the surface opposite to the surface on which the coating film A is formed. The filler b2 is mixed in a weight ratio of 10 to 70% with respect to the resin solid content, and one or more lubricants b3 selected from the group consisting of polyethylene wax, carnauba wax, and microcrystalline wax are added to the resin solid content. A conductive resin film B coated with 0.2 to 2.0 µm of a paint film mixed in a weight ratio of 1 to 5% in terms of a dry film thickness is further provided. A precoated metal sheet having excellent scratch resistance and electrical conductivity as described in the item.   One or two selected from the group consisting of a fluorine-based resin, an epoxy-based resin, a polyester-based resin, an acrylic resin, and a urethane-based resin on the chemical conversion film on the surface opposite to the surface on which the coating film A is formed A heat-dissipating and conductive resin film C containing the above base resin c1, a heat-dissipating material c2 containing at least graphite, and a conductive material c3 containing at least Ni filler is further provided. The precoat metal plate excellent in damage resistance and electroconductivity as described in any one of -3.