JP2007290358A - Precoated metal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precoated metal sheet which can prevent scratches on an optical disk and can maintains great peel strength of a stickum against a resin film and which has adhesion features with which the stickum is easily adhered to a surface of the resin film. <P>SOLUTION: The precoated sheet 1 includes a metal sheet 2 and a resin film 3 formed thereon. The resin film 3 formed on the surface of the metal sheet 2 includes an epoxy resin matrix layer 4 and soft beads 5 dispersed therein. A fine compression test wherein a single bead is deformed by 10% shows the compressive strength of the soft beads is 10 MPa or lower. The rate of content of the soft beads 5 is 5 to 50% by mass of the epoxy resin matrix layer 4, and the average particle diameter of the soft beads 5 is 1.1 to 5 times of the average thickness of the epoxy resin matrix layer 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pre-coated metal plate used for an outer plate material and a structural member such as a household electric product and an in-vehicle component for an automobile, as well as a building material and a roof material.

  Metal thin plate materials (metal plates) typified by steel plates, aluminum plates, and aluminum alloy plates have both high strength and workability. By applying various processing, household electrical products, automotive in-vehicle components, and more It is applied to various uses such as building materials. The processed metal plate used for these applications may be subjected to surface treatment for the purpose of improving the appearance and corrosion resistance. For this surface treatment, the post-coating method that has been conventionally performed after processing the metal plate into a predetermined shape has been mainstream, but recently, for the purpose of improving the work environment, simplifying the processing process and reducing costs, etc. A pre-coating method in which a pre-coated metal plate that has been previously surface-treated on a metal plate is formed into a predetermined shape and used is also fixed. Furthermore, in recent years, such pre-coated metal sheets have various functions such as fingerprint resistance, anti-sticking property, ground connection property, heat dissipation property, heat shielding property, antibacterial property, in order to meet the diversification and upgrading of products and equipment. Functional pre-coated metal plates with lubricity and the like have been developed and are widely used.

Pre-coated metal sheets are molded with surface coating applied, so the coating film not only requires excellent moldability, but the appearance after press molding becomes the product appearance as it is. Excellent surface appearance and properties are required. For example, in Patent Document 1, an aluminum alloy plate material, an epoxy resin, a urethane resin, and an acrylic resin alone or a mixture thereof is used as a base resin, SiO ₂ having a particle size of 0.1 μm or less is 5 to 40%, and a lubricant. There has been proposed a pre-coated metal plate which is coated with 5 to 60% of a coating having a thickness of 0.5 to 10 μm and has excellent formability and anti-sticking property with a friction coefficient controlled to 0.15 or less.

  The pre-coated metal plate described in Patent Document 1 is composed of an aluminum alloy plate material. In general, a pre-coated metal plate made of aluminum has been well-received for applications that require lightness. Covers for optical disk drives for mounting, frames and back covers for liquid crystal display devices, automotive electronic components such as ECUs (Electronic Control Units), car stereos, car navigation systems, optical disk auto changers, and covers and structural members It is also used. Of these, optical discs such as CDs and DVDs are installed when used in optical disc drives and optical disc autochangers. Recently, with the widespread use of writable optical disc drives, personally edited music CDs etc. The production of optical discs is also increasing. In addition, such a self-made optical disc may be used in a state where an adhesive such as an identification label for identification is adhered to the surface of the optical disc.

  However, the use of such identification labels has created new challenges. For example, a part of the identification label is peeled off due to the heat of the apparatus, and it is necessary to prepare for the risk that the exposed adhesive part will reattach to each part in the apparatus.

  As shown in FIG. 4, there is a conventional optical disc drive 20 in which the optical disc 10 is set on a tray 21 and the tray 21 is inserted into a cover 22. However, although not shown in the drawings, recently, a slot-in type optical disk drive has been developed in which a tray for setting an optical disk does not come in and out, and only the optical disk is inserted and inserted into an opening of the optical disk drive. In such a slot-in type optical disk drive, the optical disk goes in and out of the inner surface of the cover of the optical disk drive. Therefore, there is a problem that the surface of the optical disk is rubbed with the inner surface of the cover of the optical disk drive when the optical disk enters and exits, so that sliding wrinkles easily enter. It becomes.

Therefore, in the pre-coated metal plate, the adhesive is difficult to adhere in applications where the adhesive is used together, and is difficult to get dirty and oily. It is requested. In response to such problems, the present inventors use a fluorine resin as a matrix layer, and urethane beads are blended so as to have a predetermined blending ratio and a particle size such that the ratio to the film thickness is within a predetermined range. By forming a resin film on the surface of the metal plate, it has the basic and excellent formability and appearance for pre-coated metal plates that are molded and used, and it is difficult for the adhesive to adhere in applications where adhesives are used in combination. Developed a pre-coated metal plate that is resistant to dirt and oil and that has the property of not scratching the surface of an optical disc even when it comes into contact with an optical disc (Japanese Patent Application No. 2005-294109).
Japanese Patent No. 3338156 (paragraph numbers 0008 to 0017)

  However, depending on the user, even if there is a risk that an adhesive such as an identification label sticks to the resin film surface of the pre-coated metal plate, it is possible to prevent the resin film surface of the pre-coated metal plate from being scratched with double-sided adhesive tape. There is a demand to paste parts such as.

  Therefore, the present invention has been made in view of such problems, and can prevent wrinkles from entering the optical disk, can maintain a high peel strength of the adhesive to the resin film, and the adhesive is on the surface of the resin film. The present invention provides a pre-coated metal plate having the property of easily sticking.

  In order to solve the above-mentioned problem, the pre-coated metal plate according to claim 1 is a pre-coated metal plate comprising a metal plate and a resin film formed on the surface thereof, wherein the resin film is an epoxy resin matrix layer, A soft bead having a compressive strength of 10 MPa or less when deformed by 10% of a single bead according to a micro-compression test dispersed in the epoxy resin matrix layer, and the content of the soft bead is the epoxy resin matrix 5 mass% or more and 50 mass% or less with respect to the layer, The average particle diameter of the said soft bead was comprised as 1.1 times or more and 5 times or less of the average thickness of the said epoxy resin matrix layer Is.

  According to such a configuration, even if an optical disk or the like comes into contact, the soft beads are cushioned by controlling the content and average particle diameter of the soft beads dispersed in the epoxy resin matrix layer (resin film). Since it works as a material, it is difficult for wrinkles to enter the surface of an optical disk or the like due to the resin film. In addition, by making the matrix layer, which is the main component of the film, an epoxy resin, it is possible to maintain a high peel strength of the adhesive to the resin film, so that the adhesive force when attaching parts to the film surface with adhesive tape etc. is good Become.

The pre-coated metal plate according to claim 2 is configured as a pre-coated metal plate in which the soft beads are urethane beads.
According to such a configuration, urethane beads are particularly soft among soft beads, so the use of urethane beads improves the function of the soft beads as a cushioning material, and the resin film is applied to the surface of an optical disk or the like. It is possible to further prevent wrinkles from entering.

  The pre-coated metal sheet according to claim 3 is a film in which the epoxy resin matrix layer is a film obtained by crosslinking a main agent composed of a bisphenol A type epoxy resin and a curing agent composed of a urea compound or a phenol compound by heat. It is constituted as follows.

  This combination of epoxy resins is not only easy to paint by dissolving in an organic solvent, but also has a long paint life at room temperature, but can be easily cured in a short time when heated. Since the dispersibility of the soft beads and other additives is good and the coating property is excellent, it is easy to apply the coating onto the surface of the metal plate. Further, the curing reaction by heat forms a three-dimensional network structure necessary for securing the strength as a film, and further strengthens the adhesive force between the resin film and the metal plate.

The pre-coated metal plate according to claim 4 is configured such that the epoxy resin matrix layer contains a fluorine-based lubricant as an additive for imparting lubricity.
According to such a configuration, by selecting a relatively soft fluorine-based lubricant as the lubricant, it is possible to improve the lubricity without deteriorating the anti-sticking property to the optical disk. As a result, the movement of the optical disk itself and the operation of the optical disk drive when the optical disk is inserted and removed are smoothly performed.

The pre-coated metal plate according to claim 5 is configured as a pre-coated metal plate in which the fluorine-based lubricant is tetrafluoroethylene.
According to such a structure, the improvement in lubricity can be exhibited to the maximum by using tetrafluoroethylene having a high fluorine content.

In the precoated metal sheet according to claim 6, the amount of the fluorine-based lubricant added is the ratio of the fluorine concentration on the outermost surface of the resin film expressed by the following formula (1).
A (%) = {F / (F + C + O + N)} × 100 (1)
(In the formula, A is the ratio of fluorine concentration, F is fluorine mass%, C is carbon mass%, O is oxygen mass%, and N is nitrogen mass%)
The ratio of the fluorine concentration is calculated to be within the range of 10% or less.

  According to such a configuration, by controlling the ratio of the fluorine component in the film to a certain level or less, it is possible to maintain a high peel strength of the adhesive to the resin film. It is possible to avoid a decrease in the adhesive strength.

The precoated metal plate according to a seventh aspect is configured such that the average particle diameter of the soft beads is 1.5 to 4 times the average thickness of the epoxy resin matrix layer.
According to such a structure, the effect | action as a cushioning material of a soft bead improves, and it can further prevent that a wrinkle enters into the surface of an optical disk etc. by a resin film.

The precoated metal plate according to an eighth aspect is configured such that the content of the soft beads is 10% by mass or more and 40% by mass or less with respect to the epoxy resin matrix layer.
According to such a structure, the effect | action as a cushion material of a soft bead improves, and it becomes much more difficult to wrinkle on the surfaces, such as an optical disk, with a resin film. In addition, when applying an epoxy paint in which soft beads are dispersed on the surface of the metal plate in order to form a resin film, the viscosity of the epoxy paint is adjusted to a predetermined range, and the paintability is improved.

The precoated metal plate according to a ninth aspect is configured to include a corrosion-resistant film between the metal plate and the resin film.
According to such a configuration, the corrosion resistance of the pre-coated metal plate is improved, and the resin film is more firmly bonded to the metal plate.

The precoated metal plate according to claim 10 is configured such that the metal plate is an aluminum plate or an aluminum alloy plate.
According to such a structure, weight reduction can be achieved compared with the case where another metal plate is used.

  According to the pre-coated metal plate according to the present invention, the resin film formed on the surface of the metal plate has not only a basic and excellent formability and appearance for the pre-coated metal plate to be molded and used, but also a resin. By optimizing the content and average particle size of the soft beads dispersed in the film (epoxy resin matrix layer), even when the resin film surface slides on the optical disk surface, it prevents the optical disk from wrinkling. it can. In addition, it can maintain high peel strength of the adhesive to the resin film, and has good adhesion when attaching parts to the film surface with double-sided adhesive tape, etc. A pre-coated metal plate can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
1. Precoated Metal Plate As shown in FIG. 1, a precoated metal plate 1 of the present invention includes a metal plate 2 that is a base material, and a resin film 3 formed on the surface of the metal plate 2. Among these, the resin film 3 includes an epoxy resin matrix layer 4 and soft beads 5 dispersed in the epoxy resin matrix layer 4, and the content and average particle diameter of the soft beads 5 are predetermined values. It is controlled to become. Here, the surface means at least one surface of the metal plate 2. Next, each configuration will be described.

(1) Metal plate There is no restriction | limiting in particular in the metal plate 2 used by this invention, In addition to the most general cold-rolled steel plate, hot-dip galvanized steel plate, electrogalvanized steel plate, alloyed hot-dip galvanized steel plate and copper-plated steel plate Various plated steel plates such as tin-plated steel plates, alloy steel plates such as stainless steel, aluminum or aluminum alloy plates, and non-ferrous metal plates such as copper or copper alloy plates are all applicable. Here, aluminum or an aluminum alloy plate is preferable for applications that require lightness, such as covers for optical disk drives mounted on notebook computers, frames for liquid crystal display devices, and covers for in-vehicle electrical components. In particular, Al—Mg alloys represented by 5052 and 5182 specified in JIS are more preferable.

(2) Resin Film The resin film 3 includes an epoxy resin matrix layer 4 and soft beads 5 dispersed in the epoxy resin matrix layer 4 and is formed on the surface of the metal plate 2 described above.

(2-1) Epoxy Resin Matrix Layer By making the matrix layer that is the main component of the resin film 3 an epoxy resin, the peel strength of the adhesive to the resin film 3 can be maintained high. For this reason, the adhesive force when a part is attached to the film surface with an adhesive tape or the like is improved.
It is preferable that the epoxy resin matrix layer 4 is obtained by cross-linking a main agent composed of a bisphenol A type epoxy resin and a curing agent composed of a urea compound or a phenol compound by heat. This combination of epoxy resins is not only easy to paint by dissolving in an organic solvent, but also has a long paint life at room temperature, but can be easily cured in a short time when heated. Since the dispersibility of the soft beads 5 and the lubricant is good and the paint has excellent paintability, it is easy to apply a film on the surface of the metal plate 2. Further, the curing reaction by heat forms a three-dimensional network structure necessary for ensuring the strength as a film, and it is easy to further strengthen the adhesive force between the resin film 3 and the metal plate 2. . Furthermore, when a urea-based compound is used as the curing agent, it is more preferable because discoloration due to heat during the curing reaction can be suppressed.
Moreover, the epoxy resin matrix layer 4 may contain a predetermined amount of a fluorine-based lubricant typified by tetrafluoroethylene.

(2-2) Soft beads In order to apply the pre-coated metal plate 1 to a portion that slides directly with an optical disk or the like when the optical disk or the like enters or exits, it is necessary to suppress wrinkles from entering the optical disk or the like due to sliding. is there. Here, in order to prevent wrinkles from entering the optical disk or the like, it is indispensable to make the resin film 3 soft. Usually, as a method for softening the resin film 3, there are a method for lowering the glass transition temperature of the resin, a method for suppressing a crosslinking reaction between the resin and the curing agent, and the like. In order to effectively soften the resin film 3, it is most effective to soften the matrix resin which is the main component of the resin film 3, and the resin film 3 can be obtained by actually using these techniques for the matrix resin. Can be softened.

  However, if the softening of the resin film 3 is promoted by these methods, the resin film 3 has a tack property as a side effect, so that the lubricity of the resin film 3 is remarkably lowered, and the optical disk itself is removed when the optical disk is inserted and removed. There arises a problem that the movement and the operation of the optical disk drive are impaired. On the other hand, if the matrix resin of the resin film 3 is not softened, but soft fine particles, that is, soft beads 5 are added to the resin film 3 (epoxy resin matrix layer 4), the glass transition temperature of the matrix resin may be lowered. The entire resin film 3 can be softened without suppressing the crosslinking reaction. Therefore, it is possible to ensure the prevention of wrinkling on the optical disk or the like without hindering the lubricity of the resin film 3.

The softness of the soft bead 5 in the present invention refers to a soft bead 5 having a compressive strength of 10 MPa or less when deformed by 10% using a single bead (when deformed by 10% of a single bead).
As a testing machine for performing a micro compression test, for example, there is a micro compression test machine MCT-W500 manufactured by Shimadzu Corporation. By using this test machine, a compression test is performed on a single bead having a particle diameter of about 1 μm to 100 μm. It can be performed. More specifically, a single bead having a particle size of 5 to 10 μm, preferably about 8 μm, is set on the lower pressure plate of the testing machine, and simultaneously applying a load while compressing the single bead while lowering the upper pressure indenter. And the load when the bead diameter decreases by 10% is taken as the 10% compression load value. When this 10% compressive load value is P (N) and the measured particle size of the beads is d (mm), the compressive strength St (Mpa) at the time of 10% deformation can be calculated by the following equation (1) ( (See Japan Mining Association Journal, 81.10.24 (1965)). The smaller the compressive strength St (MPa) at the time of 10% deformation, the softer the beads. In the present invention, the compressive strength St (MPa) at the time of 10% deformation is required to be 10 MPa or less, and more desirably 5 MPa or less.
St = 2.8P / (Πd ² ) (1)
(However, in Equation (1), Π represents the circumference.)

  As such soft beads 5, for example, urethane beads, ethylene / methyl methacrylate copolymer (EMMA) beads, low density polyethylene (LDPE) beads and the like can be suitably used. As urethane beads, SANYO Kasei's Meltex (registered trademark), Dainichi Seika's Dymic beads (registered trademark), Negami Kogyo Art Pearl (registered trademark), etc. are preferably used. Can do. In addition, as for EMMA beads, soft beads A, soft beads B, etc. manufactured by Sumitomo Seika Co., Ltd. can be suitably used. Can do.

(Content of soft beads: 5% by mass or more and 50% by mass or less)
In order to enhance the prevention of wrinkling on an optical disk or the like, it is preferable that the content of the soft beads 5 is larger than that of the epoxy resin matrix layer 4. When the content of the soft beads 5 is less than 5% by mass, the amount of the soft beads 5 fixed in the epoxy resin matrix layer 4 is small, the function as a cushioning material is lowered, and the anti-fouling property is inferior. In addition, when the content of the soft beads 5 is increased, the viscosity of the paint in which the soft beads 5 are dispersed increases, and therefore it is assumed that the paint is applied to the metal plate 2 by roll coating or the like. However, paintability with a uniform film thickness decreases. For the above reasons, the content of the soft beads 5 is set to 5% by mass or more and 50% by mass or less with respect to the epoxy resin matrix layer 4. Moreover, in order to ensure the anti-fouling performance at a high level, the content of the soft beads 5 is preferably 10% by mass or more, and in order to ensure more stable paintability, the content of the soft beads 5 Is preferably 40% by mass or less.

(Average particle diameter of soft beads: 1.1 times to 5 times the average thickness of the epoxy resin matrix layer)
In order to ensure that the soft beads 5 are prevented from being scratched on an optical disk or the like, it is important that the average particle diameter of the soft beads 5 is larger than the average thickness of the epoxy resin matrix layer 4. As a result, as shown in FIG. 1, the cross-sectional shape of the resin film 3 becomes a fine concavo-convex shape in which the portion where the soft beads 5 are present is convex, so that the contact area between the optical disk and the epoxy resin matrix layer 4 is increased. In addition, since soft soft beads 5 act as a cushioning material at the contact portion, it is possible to ensure the prevention of wrinkling on an optical disk or the like.

  Here, when the average particle diameter of the soft beads 5 exceeds 5 times the average thickness of the epoxy resin matrix layer 4, it is difficult for most of the soft beads 5 to be fixed in the epoxy resin matrix layer 4. Therefore, the effect of preventing sliding wrinkles on the optical disk or the like is reduced. Further, when the average particle diameter of the soft beads 5 is less than 1.1 times the average thickness of the epoxy resin matrix layer 4, the soft beads 5 having a small particle diameter are easily embedded in the epoxy resin matrix layer 4. Therefore, the effect of preventing sliding wrinkles on the optical disk or the like is reduced. Therefore, the average particle diameter of the soft beads 5 is set to be 1.1 to 5 times the average thickness of the epoxy resin matrix layer 4. The average thickness of the epoxy resin matrix layer 4 is more preferably 1.5 times or more and 4 times or less.

  If the average particle diameter of the soft beads 5 and the average thickness of the epoxy resin matrix layer 4 are maintained in such a relationship, it is possible to prevent sliding wrinkles from entering the optical disk or the like. Even if the relationship is maintained, if the soft bead 5 having a particle size larger than necessary is used, the average thickness of the epoxy resin matrix layer 4 must be increased, so that the resin film 3 becomes thicker than necessary. On the contrary, when soft beads 5 smaller than necessary are used, it is industrially necessary to control the relationship between the average particle diameter of the soft beads 5 and the average thickness of the epoxy resin matrix layer 4. It becomes difficult. Therefore, it is desirable to use a soft bead 5 having an average particle diameter of about 5 to 30 μm, and the average thickness of the epoxy resin matrix layer 4 is preferably 3 μm or more and 10 μm or less. The average thickness of the epoxy-based resin matrix layer 4 is a value obtained by measuring the mass of the resin film 3 per unit area and converting the specific gravity to 1.

  The particle size of the soft beads 5 actually has a distribution. For example, the particle size distribution of beads of about 8 μm with a 50% cumulative volume particle size is distributed from a minimum of about 1 μm to a maximum of about 20 μm (Daimic Beads (registered trademark) particle size on the website of Dainichi Seika) Distribution (synonymous with particle size distribution)). Therefore, in the present invention, the average particle diameter is adopted as an index of the particle diameter of the soft beads 5. The average particle diameter is an integrated volume 50% particle diameter measured with a laser diffraction particle size distribution analyzer or the like in a state where the soft beads 5 are dispersed in water.

(Rate of fluorine concentration in resin film)
When the epoxy resin matrix layer 4 contains a fluorine-based additive, the resin film 3 has a fluorine concentration ratio at the outermost surface of the resin film 3 expressed by the following formula (1)
A (%) = {F / (F + C + O + N)} × 100 (1)
(In the formula, A is the ratio of fluorine concentration, F is fluorine mass%, C is carbon mass%, O is oxygen mass%, and N is nitrogen mass%)
The ratio of the fluorine concentration is 10% or less, more preferably 7% or less.

  Here, the ratio of the fluorine concentration is measured and converted by ESCA (X-ray photoelectron analyzer) using fluorine mass%, carbon mass%, oxygen mass% and nitrogen mass% on the outermost surface of the resin film 3. , Calculated by the equation (1). The outermost surface of the film referred to here is the surface on the side to which the adhesive tape adheres, that is, the outermost surface of the precoated metal plate 1 and is not the interface between the resin film 3 and the metal plate 2.

  Specifically, the ratio of the fluorine concentration on the outermost surface of the film is the argon sputtering time when each elemental analysis is performed by ESCA while digging by argon sputtering or the like from the surface of the precoated metal plate 1 to the inside. It is a value based on each element mass% obtained in a zero state. That is, since the surface is not dug at all by argon sputtering or the like, it can be defined as the outermost surface state.

  In addition, when the epoxy resin matrix layer 4 contains a predetermined or more fluorine additive, the ratio of the fluorine concentration on the outermost surface of the film may exceed 10%. In this case, since the ratio of fluorine present on the outermost surface of the resin film 3 and involved in the peelability of the adhesive is too high, the peel strength when attaching parts with a double-sided adhesive tape is increased and stable. It will not be possible to maintain the adhesive strength.

(Corrosion resistant coating)
Next, the precoated metal plate 1 of the present invention may be provided with a corrosion-resistant film (not shown) between the metal plate 2 and the epoxy resin matrix layer 4 including the soft beads 5. By forming the corrosion-resistant film, corrosion resistance is imparted to the precoated metal plate 1 and adhesion between the metal plate 2 and the resin film 3 is improved. The structure of the corrosion resistant film is, for example, as follows.

The corrosion resistant coating is a conventionally known corrosion resistant coating containing Cr or Zr as a component, such as a phosphate chromate coating, a chromate chromate coating, a zirconium phosphate coating, a zirconium oxide-based coating, a coating type chromate coating, or a coating type zirconium coating. Etc. can be used as appropriate. Moreover, as for the adhesion amount of a corrosion-resistant film | membrane, 10-50 mg / m < ² > is preferable in Cr or Zr conversion value. When the adhesion amount of the corrosion-resistant film is less than 10 mg / m ^2, the entire surface of the metal plate 2 cannot be uniformly coated, and it becomes difficult to ensure the corrosion resistance, so that it cannot withstand long-term use. On the other hand, if the adhesion amount exceeds 50 mg / m ² , cracking (peeling) occurs in the corrosion-resistant film itself in press molding or the like, and it becomes difficult to maintain high corrosion resistance for a long period of time.

2. Manufacturing method of pre-coated metal plate The manufacturing method of the pre-coated metal plate according to the present invention includes a step of applying an epoxy-based paint in which soft beads are dispersed to the surface of the metal plate, and a baking treatment of the applied epoxy-based paint. A method of combining with a step of forming a film is known. Hereinafter, each step will be described.

The first step is to apply an epoxy-based paint in which soft beads are dispersed on the surface of the metal plate. The epoxy-based paint used is composed of a main agent composed of a bisphenol A type epoxy resin and a urea compound or a phenol compound. It is preferable that the curing agent to be dissolved is dissolved in an organic solvent. Moreover, it is desirable to add a lubricant such as natural wax, petroleum wax, synthetic wax or a mixture thereof in addition to the soft beads, which are essential components, in the epoxy paint, and among them, represented by ethylene tetrafluoride. Fluorine-based lubricant, the ratio of fluorine concentration on the outermost surface of the resin film is expressed by the following formula (1)
A (%) = {F / (F + C + O + N)} × 100 (1)
(In the formula, A is the ratio of fluorine concentration, F is fluorine mass%, C is carbon mass%, O is oxygen mass%, and N is nitrogen mass%)
Is preferably used in a range where the fluorine concentration ratio does not exceed 10%, and more preferably in a range not exceeding 7%. Furthermore, additives such as dyes and pigments for coloring purposes, various inorganic fillers for improving the hardness and anti-fogging property of the resin film, and conductive additives are within the scope of the claims of the present invention. Can be added freely.

  Examples of the method for dispersing the soft beads in the epoxy paint include ultrasonic treatment, stirring treatment using a magnet stirrer or impeller stirrer, stirring treatment using a homogenizer, attritor, ball mill, bead mill, and the like.

  The epoxy paint can be applied by any method such as brush, roll coater, curtain flow coater, roller curtain coater, electrostatic coating machine, blade coater, die coater, etc., but the coating amount is particularly uniform. In addition, it is more preferable to use a roll coater that is easy to work. The coating amount is appropriately set in consideration of the conveyance speed of the metal plate, the rotation direction and the rotation speed of the roll coater, etc. so that an epoxy resin matrix layer having an average thickness of 3 to 10 μm is formed on the surface of the metal plate. To do.

  Prior to the application of the epoxy paint, a degreasing step for degreasing the surface of the metal plate may be provided. For example, an aqueous alkali solution is sprayed on the surface of the metal plate, and then washed with water to degrease the surface of the metal plate. Further, as described above, when a corrosion-resistant film is provided between the metal plate and the epoxy resin film, a chemical conversion treatment solution containing chromium ions or the like is sprayed on the surface of the metal plate after the degreasing step. A corrosion-resistant film can be formed.

  Next to the step of applying the epoxy coating to the metal plate is a step of forming a resin film (epoxy resin matrix layer including soft beads) from the applied epoxy coating, and the epoxy coating applied to the metal plate Is baked to cure (crosslink) the epoxy paint. Then, the epoxy coating is cured (crosslinked), whereby the resin film is firmly bonded to the metal plate. Furthermore, soft beads are fixed to the epoxy resin matrix layer.

  The baking temperature does not affect the scratch resistance of the coated optical disk or the adhesive property of the double-sided adhesive tape, but if the baking temperature is less than 200 ° C, the epoxy paint is not sufficiently cured (crosslinked). When the baking temperature exceeds 300 ° C., the epoxy paint is thermally deteriorated (decomposed), and is preferably 200 ° C. or higher and 300 ° C. or lower. The baking time is preferably 20 to 60 seconds. If the treatment time is less than 20 seconds, the baking tends to be insufficient. If the treatment time exceeds 60 seconds, the baking treatment time is too long, and the productivity per hour tends to decrease. In addition, the baking treatment is performed using, for example, a hot air furnace, an induction heating furnace, a near infrared furnace, a far infrared furnace, or an energy beam curing furnace.

  Next, in the precoated metal plate according to the present invention, the type and average thickness of the matrix layer of the resin film, the type of beads dispersed in the matrix layer, hardness (compression strength at 10% deformation), content rate, average Examples and comparative examples in which the prevention of wrinkling on optical disks, adhesive peelability and paintability were confirmed when the ratio of the surface fluorine concentration adjusted by the particle diameter and the amount of tetrafluoroethylene added were changed will be described. .

(Examples 1-12)
As Examples 1 to 12, precoated metal sheets were produced according to the above production method. Each structure of a precoat metal plate is as follows.
(Metal plate)
The aluminum alloy plate of thickness 0.5mm and JIS regulation 5052-H34 was used.
(Corrosion resistant coating)
A phosphate chromate film was formed on both sides of the aluminum alloy plate. The adhesion amount of the phosphoric acid chromate film was 20 mg / m ² in terms of Cr.
(Resin film)
An epoxy-based paint in which soft beads having a compressive strength at the time of deformation of 10% specified in the present invention and ethylene tetrafluoride powder are dispersed is applied to the outermost surface of the phosphate chromate film, and the baking temperature (peak temperature of the metal plate) A baking treatment was performed at 250 ° C. to form a resin film (epoxy resin matrix layer). Here, urethane beads were used as the soft beads. In Example 10 where the surface fluorine concentration was 0%, no tetrafluoroethylene powder was added.

  Here, as the epoxy paint, a one-pack type epoxy urea paint in which a main agent composed of a bisphenol A type epoxy resin and a curing agent composed of a urea compound were dissolved in an organic solvent was used. In this case, a product manufactured by Dainippon Ink & Chemicals, Inc. was used, but paints having the same composition can be obtained from Kansai Paint Co., Ltd. or Nippon Paint Co., Ltd.

(Comparative Examples 1-12)
As a control for Examples 1 to 12, precoated metal sheets of Comparative Examples 1 to 12 were prepared. Comparative Example 1 used an epoxy-based paint containing no soft beads, Comparative Examples 2 and 3 were those in which the soft bead content did not satisfy the claims of the present invention, and Comparative Examples 4 and 5 were averages of soft beads. The relationship between the particle size and the average thickness of the epoxy-based resin matrix layer does not satisfy the claims of the present invention, Comparative Examples 6 and 7 show that the fluorine on the outermost surface of the film is increased as a result of increasing the amount of tetrafluoroethylene powder added. The concentration ratio does not satisfy the claims of the present invention, Comparative Examples 8 and 9 use resin matrix layers different from the epoxy type, and Comparative Example 10 uses resin matrix layer types. Is different from the epoxy type, and the ratio of fluorine concentration does not satisfy the claims of the present invention, Comparative Examples 11 and 12 do not have the compressive strength at the time of 10% deformation defined in the present invention. Beads (i.e., not a soft beads) is obtained by using.

  Next, for the resin films of the precoated metal plates of Examples 1 to 12 and Comparative Examples 1 to 12, the ratio of the fluorine concentration on the outermost surface of the resin film was measured, and the results are shown in Table 1. In addition, the measuring method of each characteristic was as follows.

(Percentage of fluorine concentration)
The outermost surface of the resin film was measured by ESCA (manufactured by Shimadzu Corporation) to obtain atomic% of 4 elements of fluorine, carbon, oxygen and nitrogen. These atomic% were converted into mass% using the atomic weight of each element. Using the fluorine mass% (F), the carbon mass% (C), the oxygen mass% (O), and the nitrogen mass% (N), the ratio of the fluorine concentration (A (%)) is expressed by the following formula (1). Calculated.
A (%) = {F / (F + C + O + N)} × 100 (1)

  Here, the outermost surface of the coating refers to a state where the surface of the pre-coated metal plate prepared above is measured as it is, that is, in a state where the argon sputtering time is zero.

  Further, a resin film composed of an epoxy resin matrix layer and beads is a non-uniform film when viewed microscopically. Therefore, when analyzing with ESCA, if the area of the analysis surface is too narrow, information indicating that the epoxy resin matrix layer is locally rich, or conversely, information indicating that the beads are locally rich is obtained. Therefore, in this case, the ratio of the fluorine concentration may vary at every measurement timing. Therefore, the area of the analysis surface was 3 mmφ so that average information on the resin film could be obtained. Here, it goes without saying that both the outermost surface of the coating and the inside of the coating were selected and measured at sites not contaminated with oils or the like.

  Next, the wrinkle-preventing property and adhesive tape adhesiveness of the precoated metal plates of Examples 1-12 and Comparative Examples 1-12 to the optical disk were measured and evaluated, and the results are shown in Table 1. In addition, the measurement and evaluation methods of the anti-sticking property and the adhesive tape adhesive property were as follows.

(Prevention of wrinkles on optical discs)
The recording surface of a commercially available optical disk was brought into contact with the resin film surface of the precoated metal plate and rubbed 10 times back and forth while gently pressing it with a finger, and then the wrinkles on the optical disk surface were visually evaluated. At this time, in comparison with the optical disk sample shown in FIGS. 2 to 3, a sample with a close wrinkle state was selected, and the determination of the sample was taken as the determination result of the anti-fouling property of the precoated metal plate. However, wrinkles generated by rubbing the edge of the optical disk were excluded, and only the sliding wrinkles between the resin film surface and the optical disk recording surface were determined.
Judgment is “◎” for excellent anti-sticking property, “○” for good anti-sticking property, “△” for slightly anti-sticking property, and poor anti-sticking property. The thing was made into "x".

(Adhesive tape adhesive)
The adhesive tape peel strength was measured by a 180 degree peel test defined in JIS K6854-2. As the adhesive tape, a commercially available double-sided adhesive tape (Double-sided adhesive tape manufactured by Sliontec Co., Ltd., product number 5460, tape width 6 mm) was used. Moreover, as a measurement condition, a pre-coated metal plate having a length of 100 mm × width of 60 mm and an adhesive tape having a length of 100 mm × width of 6 mm were used, and the peel strength was set to 50 mm / min. In addition, the adhesive evaluation in Table 1 is “○” when the adhesive tape peel strength is 2.0 N / 6 mm or more and excellent adhesiveness, and “X” when less than 2.0 N / 6 mm. Was bad.

  As shown in Table 1, each of the precoated metal plates of Examples 1 to 12 has an adhesive tape peel strength exceeding 2.0 N / 6 mm, exhibits excellent adhesive tape adhesiveness, and prevents wrinkles on an optical disk. Was also good or excellent. Further, as the content of urethane beads increases, the tendency to improve the anti-sticking property is recognized. If the content is 5% by mass or more, it is generally good, and if the content is 10% by mass or more, excellent wrinkles are achieved. The anti-sticking property was shown.

  On the other hand, the precoated metal plates of Comparative Examples 1, 2, 4, 5, 11, and 12 all had an adhesive tape peel strength of more than 2.0 N / 6 mm, and were excellent in adhesive tape adhesiveness. It was inferior in the anti-sticking property. Further, Comparative Examples 6 to 10 were all excellent in the ability to prevent wrinkling on the optical disc, but the adhesive tape peel strength was below 2.0 N / 6 mm, and the adhesive tape peelability was inferior. Furthermore, in Comparative Example 3, the soft bead content was 60% by mass, which exceeded the scope of the claims of the present invention. Therefore, the viscosity of the epoxy-based paint was remarkably increased and the paintability was difficult.

It is sectional drawing which shows typically the structure of the precoat metal plate which concerns on this invention. FIG. 2 is a micrograph of an optical disc sample for determining the prevention of wrinkling on an optical disc, wherein (a) is a sample having excellent anti-sticking properties, and (b) is a sample having good anti-sticking properties. FIG. 2 is a micrograph of a sample of an optical disc that is used to determine the prevention of wrinkling on an optical disc, where (a) is a sample with a slightly poor anti-sticking property and (b) is a sample with a poor anti-sticking property. . It is a perspective view which shows the structure of an optical disk drive roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Precoat metal plate 2 Metal plate 3 Resin film 4 Epoxy resin matrix layer 5 Soft bead 10 Optical disk 20 Optical disk drive 21 Tray 22 Cover

Claims (10)

A pre-coated metal plate comprising a metal plate and a resin film formed on the surface thereof, wherein the resin film is dispersed in an epoxy resin matrix layer and the epoxy resin matrix layer, according to a micro compression test A soft bead having a compressive strength of 10 MPa or less when deformed by 10% of a single bead,
The content of the soft beads is 5% by mass or more and 50% by mass or less with respect to the epoxy resin matrix layer,
The precoated metal sheet, wherein an average particle diameter of the soft beads is 1.1 to 5 times an average thickness of the epoxy resin matrix layer.   The precoated metal sheet according to claim 1, wherein the soft beads are urethane beads.   The epoxy resin matrix layer is a film obtained by crosslinking a main agent composed of a bisphenol A type epoxy resin and a curing agent composed of a urea compound or a phenol compound by heat. 2. The precoated metal plate according to 2.   The pre-coated metal sheet according to any one of claims 1 to 3, wherein the epoxy-based resin matrix layer contains a fluorine-based lubricant as an additive for imparting lubricity.   The precoated metal sheet according to claim 4, wherein the fluorine-based lubricant is tetrafluoroethylene. The amount of the fluorine-based lubricant added is the ratio of the fluorine concentration on the outermost surface of the resin film.
A (%) = {F / (F + C + O + N)} × 100 (1)
(In the formula, A is the ratio of fluorine concentration, F is fluorine mass%, C is carbon mass%, O is oxygen mass%, and N is nitrogen mass%)
6. The precoated metal sheet according to claim 4, wherein the fluorine concentration ratio is within a range of 10% or less when calculated by:   The average particle diameter of the soft beads is 1.5 times to 4 times the average thickness of the epoxy resin matrix layer, according to any one of claims 1 to 6. Pre-coated metal plate.   8. The precoated metal according to claim 1, wherein a content of the soft beads is 10% by mass to 40% by mass with respect to the epoxy resin matrix layer. Board.   The precoated metal sheet according to any one of claims 1 to 8, further comprising a corrosion-resistant film between the metal plate and the resin film.   The pre-coated metal plate according to any one of claims 1 to 9, wherein the metal plate is an aluminum plate or an aluminum alloy plate.