JP2010247396A - Coated metal plate and electronic instrument box using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated metal plate having the same corrosion resistance of a plane part and press-workability as those of the conventional two layer-coated film and which can be manufactured by high speed operation, and to provide a processed product using the same. <P>SOLUTION: The coated metal plate includes: a metal plate; a chemical conversion treated film including one layer of an inorganic coat layer or an inorganic and organic composite coat layer formed on at least one surface of the metal plate; and a colored coat layer formed on the chemical conversion treated film. The colored coat film includes not less than 5 mass% to less than 15 mass%, based on a solid component of coating, of silica showing oil absorption of 50 to 1,000 ml/100 g and having an average particle diameter of not more than 10 μm. The major resin of the colored coated film is a water-soluble or water-dispersible polyester resin or urethane resin. The colored coat film further preferably includes a curing agent and a curing catalyst. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coated metal plate excellent in press workability and flat surface corrosion resistance, in which one layer of a chemical conversion treatment film and one layer of a colored coating film are sequentially formed on the metal plate. The coated metal plate of the present invention can be suitably used as a casing or material for home appliances such as flat panel televisions, refrigerators, fan heaters, and air conditioner outdoor units, building materials, and automobile parts. In the present invention, the “casing” means a box-shaped body that accommodates a product or its internal components.

  Usually, a coated metal plate (in the following description, a zinc-based plated steel sheet that is a coated steel sheet in which a coating film is formed on a zinc-based plated steel sheet that is a steel sheet having a zinc-containing plating layer is taken as a specific example). Then, the outer surface coating film to be the design surface is formed from a plurality of coating films such as an undercoat coating film, a top coating film, or an undercoat coating film, an intermediate coating film, and a top coating film. In such a coating film, there is a role for each layer, the undercoat film plays a role as ensuring adhesion and corrosion resistance with the underlying steel sheet, and the overcoat film is designed and resistant to contamination. Responsible for performance, weather resistance, scratch resistance, and chemical resistance. As for the intermediate coating film, it is often used to supplement the role of each of the undercoat and topcoat films.

  In addition, in the lower layer of the undercoat film, a chemical conversion treatment film of a thin film is usually formed in order to ensure adhesion between the zinc-based plated steel sheet and the undercoat film. The coated steel sheet is formed through a single-sided three-coating three-baking process.

  Such a coated steel sheet has a large number of processes during painting and baking, and requires a long time for production. Therefore, an improvement means for reducing the number of processes is desired from the viewpoint of rationalization of painting work and resource saving. Also, lines that can only be coated with 2 coats and 2 bake processes, including chemical conversion coatings, for example, in-line coater equipment after hot-dip galvanizing or electrogalvanizing lines, and only 2 coats and 2 bakes due to space requirements. Such a coated steel sheet cannot be manufactured in a possible coating line or the like.

  Therefore, it has the same performance as a 3-coat 3-bake coated steel sheet including a conventional chemical conversion coating, and has a structure in which one colored coating film is formed on the upper layer of the chemical conversion coating, and a 2-coat 2-bake process. The coated steel sheet which can be manufactured in is desired.

On the other hand, it is desired to use a water-based paint for a paint composition used for producing a coated steel sheet. Compared with solvent-based paints, water-based paints can reduce the burden on the insulator used to burn organic solvents generated during paint baking, and the amount of CO ₂ emitted therefrom Can be reduced. In addition, if a completely water-based paint is used, it is not necessary to use the insulator itself.

  That is, by using a water-based paint composition corresponding to a total of two layers including one chemical conversion treatment layer, it is possible to reduce the environmental load imposed by the painting process and rationalize the painting work.

  However, when the conventional paint for coated steel sheet is used as it is as a single coating film, the undercoat paint alone is insufficient in processability and chemical resistance, and the topcoat paint alone has adhesion to the underlying steel sheet. Corrosion resistance becomes insufficient. Although it is conceivable to use a powder paint instead of the liquid paint, the powder paint has a thick film thickness and takes time to be cured. Therefore, when considering the rationalization of painting work and resource saving, it is necessary to design a single color coating that has both the undercoat and overcoat functions of the coated steel sheet and can be cured in a short time. Become.

  By the way, a pre-coated steel sheet (which means a coated steel sheet in which a painting process is performed in the primary processing stage, and in the present invention, “coated steel sheet” means a pre-coated steel sheet) has high hardness and excellent stain resistance. Many performances such as excellent chemical resistance, excellent water resistance, and excellent corrosion resistance are required. In particular, since work such as pressing is performed after painting and baking, it is particularly important that the press workability is good in the coated steel sheet.

  Here, “the press workability is good” means that a high surface pressure is applied to the coating film on the steel plate in the pressing process even when the mold temperature rises due to continuous pressing. Furthermore, the occurrence of fatal obstacles in the pressing process such as galling of the coated steel sheet is suppressed, which means that a stable pressing process can be performed.

In addition, the following is mentioned as a cause of this galling phenomenon.
(I) Since the coating film is excessively soft, the coating film is excessively deformed at a relatively low surface pressure and strongly adheres to the mold, and therefore, the sliding resistance between the mold and the coating film Will rise excessively.
(Ii) Since the coating film is excessively hard, the coating film cannot follow the deformation of the base material during press working, and the coating film is cracked. Increase the sliding resistance.

  With respect to the required characteristics of such a coated steel sheet, for example, in Patent Document 1, a specific polyester resin, melamine resin (curing agent) is used for the purpose of obtaining a coating film excellent in hardness, stain resistance and weather resistance. There have been proposed coating compositions containing the above and coated steel sheets using the same.

  Moreover, in patent document 2, by coating the coating composition which mix | blended polyester resin, a melamine resin (curing agent), a rust preventive pigment, organic polymer fine particles, etc., workability, corrosion resistance, adhesiveness, and resistance to one coat are applied. Coated steel sheets that satisfy impact, scratch resistance, and design have been proposed.

  Furthermore, in Patent Document 3, a conversion coating not containing a zinc-based plating layer and chromium is sequentially formed on both surfaces of a steel plate, and a polyester-based resin cured with a crosslinking agent on the conversion coating on one surface of the steel plate; A single coating film containing resin particles having an average particle diameter of 3 to 40 μm, a glass transition temperature of 70 to 200 ° C. and higher hardness than the polyester resin has been proposed.

Japanese Unexamined Patent Publication No. 63-7878 JP 63-114635 A JP 2007-269010 A

  However, all of the coated steel sheets described in Patent Documents 1 and 2 are assumed to use a chromate-based film containing chromium as a chemical conversion film, which is environmentally undesirable. In addition, since the polyester resin used is not designed to provide a thin coating film with a strength sufficient to withstand the stress during severe press processing such as drawing, sufficient press workability is achieved. I can't get it.

  Moreover, about the coated steel plate described in patent document 3, although chromium is not contained and a coating film is 1 layer, it is not described at all about ensuring corrosion resistance of the coating-film plane part concerned in that case. .

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to apply a conventional two-layer coating film (a coating layer having an undercoat layer and an overcoat layer formed on a metal material on which a chemical conversion treatment film is formed). It is to provide a coated metal plate having a flat surface coating film corrosion resistance and press workability equivalent to those of a film) and capable of high-speed operation during production, and a processed product (for example, a casing) using the same. .

  As a result of repeated studies to solve the above problems and to obtain a coated metal plate having excellent performance while the colored coating film has a single-layer structure, the present invention has been developed on at least one surface of the metal plate. The present inventors have found that a coated metal sheet excellent in flat part corrosion resistance, end face corrosion resistance, and press workability can be obtained by sequentially forming a specific chemical conversion coating layer and a specific colored coating film. . The present invention has been made based on such findings, and the gist of the present invention is as follows.

  (1) A metal plate, a chemical conversion coating formed of at least one inorganic coating layer or an inorganic / organic composite coating layer formed on at least one surface of the metal plate, and a single layer formed on the chemical conversion coating The colored coating film comprises a silica having an oil absorption of 50 ml / 100 g or more and 1000 ml / 100 g or less and an average particle size of 10 μm or less to 5% by mass or more and 15% by weight based on the solid content of the paint. A coated metal sheet comprising less than mass%, and wherein the main resin of the colored coating film is a water-soluble or water-dispersed polyester resin or urethane resin.

(2) The coated steel sheet according to (1) above, wherein the total amount of the pigment in the colored coating film is 7% by mass or more and 40% by mass or less based on the solid content of the paint.
(3) The coated steel sheet according to (1) or (2) above, wherein the thickness of the colored coating film is 2 μm or more and 10 μm or less.

  (4) The main resin of the colored coating film is a water-soluble or water-dispersed polyester resin, the glass transition temperature of the main resin in the colored coating film is 0 ° C. or higher and 30 ° C. or lower, and the molecular weight is 10,000 or higher and 30000. The coated steel sheet according to any one of the above (1) to (3), wherein:

  (5) The main resin of the colored coating film is a water-soluble or water-dispersed polyester resin, and the coating material for forming the colored coating film is 0.1 part by mass or more and 2 parts by mass with respect to 100 parts by mass of the paint. The coated steel sheet according to any one of the above (1) to (4), which contains the following curing catalyst.

  (6) The main resin of the colored coating film is a water-soluble or water-dispersed urethane resin, the glass transition temperature of the main resin in the colored coating film is 0 ° C. or less, and the molecular weight is less than 100,000. The coated steel sheet according to any one of (1) to (3) above, which is characterized.

  (7) The colored coating film contains water-soluble melamine as a curing agent in an amount of 5% by mass to 30% by mass with respect to the resin solid content, and 0.1 parts by mass of the curing catalyst with respect to 100 parts by mass of the colored paint. The coated steel sheet according to any one of the above (1) to (6), comprising 2 parts by mass or less.

(8) attached amount of the inorganic coating or inorganic-organic composite coating film formed by the, in any one of (1) to (7), characterized in that it is 20 mg / ^{m 2} or more 1000 mg / ^{m 2} or less The coated steel sheet described.

(9) The coated steel sheet according to any one of (1) to (8) above, wherein the metal sheet is a plated steel sheet containing zinc.
(10) A housing comprising the coated metal plate according to any one of (1) to (9) so that a surface on which a colored coating film is formed is on an outer side.

  Coating with excellent flat surface corrosion resistance, press workability, and coating film hardness by sequentially forming one layer of chemical conversion coating layer and one layer of colored coating film according to the present invention on at least one surface on a metal plate It becomes possible to provide a metal plate and a processed product using the metal plate, for example, a housing.

  Furthermore, if the coating film having the same configuration as the coating film is formed on the surface opposite to the surface on which the coating film is formed (back surface), both surfaces have good corrosion resistance. A coated steel sheet having particularly excellent corrosion resistance suitable for a housing of a product placed in a harsh environment such as a semi-outdoor is obtained. On the other hand, if one or two chemical conversion coating layers of a thin film that can ensure conductivity are formed on the back surface, it is suitable for the housing of home appliances and electronic / electric equipment installed indoors for thin TV applications. Coated steel sheet is obtained.

  The present invention broadly discloses two means as means for achieving both press workability and flat surface corrosion resistance in a coated steel sheet provided with a chemical conversion treatment film and a single color coating film formed thereon.

One is a means for improving the press workability with a single colored coating film by using the binder resin (and curing agent, curing catalyst) contained in the colored coating film as a specific resin (first embodiment).
The other is to improve the press workability with lubricating oil by assuming that the lubricating oil is applied to the surface of the colored coating film during press processing so that the properties of the colored coating film do not deteriorate with the lubricating oil. It is a means of maximizing use (second embodiment).
In any form, the anticorrosive pigment contained in the colored coating film includes silica having a predetermined oil absorption and an average particle size, thereby enhancing the corrosion resistance of the coating film surface.

I. 1st embodiment The coating metal plate of this embodiment is a metal plate, and the chemical conversion treatment film which consists of one inorganic coating layer or inorganic-organic composite coating layer formed on at least one surface of this metal plate, A colored coating film formed on the chemical conversion coating film, and the colored coating film contains silica having an oil absorption of 50 ml / 100 g or more and 1000 ml / 100 g or less and an average particle diameter of 10 μm or less. The main resin of the colored coating film is a water-soluble or water-dispersed polyester resin containing 5% by mass or more and less than 15% by mass with respect to the solid content of the paint.

  Here, the “colored coating film” means a film-like body formed on a metal plate by baking a paint (hereinafter also referred to as “colored paint”) which is a liquid composition having a coloring component. To do.

  “Paint solid content” means a solid content when a colored paint is baked, and this “paint” does not include a treatment liquid for a paint base treatment. The mass of the paint solids is measured as follows. That is, a predetermined amount of paint or paint raw material (main resin or the like) is placed in an oven, and the inside of the oven is heated while measuring its mass to solidify the paint or paint raw material. The mass measurement value of the solidified product when solidified until there is no mass change in the oven is defined as the mass of the solid content of the paint. Therefore, “mass% with respect to the solid content of the paint” refers to a mass ratio when the weight measurement value is 100%. Examples of the component constituting the paint solid content include other components such as a binder component, a pigment, and resin particles.

  “Resin solid content” refers to the solid content derived from the binder component in the solid content (coating film) when the colored paint is baked. Therefore, “mass% with respect to the resin solid content” substantially means a mass ratio when the weight measurement value when only the binder component is cured is 100%. As will be described later, the binder component is composed of a binder resin, which is a main component of the binder component, a curing agent, and other components (such as a curing catalyst).

The “main resin” refers to a resin that has a content of 60% by mass or more based on the total binder resin and is the main component of the binder resin.
The “average particle size” of the pigment refers to the average primary particle size when the pigment present alone in the coating film is present alone, and the pigment particle size at the time of aggregation when the pigments are aggregated together. It means the average secondary particle size to be expressed, and is preferably obtained by the following measurement method. First, the coated steel sheet on which the coating film is formed is cut to expose the cross section, and the cross section is further polished. The cross section thus obtained is observed with an electron microscope, and an observation image of the cross section in the coating film is obtained. Select several pigments in the field of view of the observed image, measure the long side length and short side length of each pigment, calculate the average value of these long sides and the average value of the short sides, and The average primary particle size is calculated on average.

  Note that the numerical value of the average primary particle diameter varies slightly depending on the measurement method. For example, it may vary depending on the measurement principle when using a particle size distribution meter, and depending on the image processing method in the case of image analysis. However, the range of the particle size of the pigment defined in the present invention takes such fluctuations into consideration, and any particle size obtained by any method is within the range defined in the present invention. It is possible to stably achieve the effects of the period.

  In the coated metal plate according to the present invention, the surface on which the colored coating film is formed is an outer surface that directly touches the eyes of the user when in use. Hereinafter, the surface on which the colored coating film is formed is referred to as “front surface”, and the surface opposite to the front surface is referred to as “back surface”.

1. Substrate metal plate The plate-like substrate used for the coated metal plate of the present embodiment is not particularly limited, and a plate-like member made of any metal may be used. Examples of materials generally used for painted metal plates include steel (iron-based alloy), aluminum and its alloys, magnesium and its alloys, and the like. Among these, for coated steel sheets whose base material is steel, a zinc-based plated steel sheet having a zinc-containing plating layer on its surface, that is, a zinc-plated steel sheet or a zinc alloy-plated steel sheet, or alloying these platings with a substrate. Often, alloyed plated steel sheets are used.

  Examples of such galvanized steel sheets include hot dip galvanized steel sheets, electrogalvanized steel sheets, galvannealed steel sheets, aluminum-zinc alloy plated steel sheets, iron-zinc alloy plated steel sheets, nickel-zinc alloy plated steel sheets, A nickel-zinc alloy plated steel sheet after the blackening treatment is exemplified.

The coating amount (per one side) of the galvanized steel sheet is not particularly limited. Considering the fact that sufficient corrosion resistance (particularly end face corrosion resistance) cannot be obtained when the amount of adhesion is excessively small, and there are problems such as high manufacturing costs and low workability when the amount of adhesion is excessively large. And what is necessary is just to set suitably according to a use. In general, the amount of adhesion is preferably 3 g / m ² or more and 50 g / m ² or less in the case of an electroplated steel sheet, and 15 g / m ² or more and 100 g / m ² or less in the case of a hot dip galvanized steel sheet including an alloyed hot dip galvanized steel sheet.

In particular, hot dip galvanized steel sheets with a large amount of adhesion are suitable for outdoor applications, and electrogalvanized steel sheets are sufficient for relatively mild environments such as indoor applications.
Moreover, when heat dissipation etc. are requested | required, it is preferable to use the galvannealed steel plate with high thermal emissivity of the plated steel plate itself, or the nickel- zinc alloy plated steel plate after blackening treatment.
The thickness of the plate-like member constituting the base material is appropriately determined depending on the use, but there is a concern that press workability is lowered when it is excessively thick.

2. Chemical conversion coating One or more chemical conversion coatings are formed in accordance with the present invention on both surfaces of a metal plate, for example, a galvanized steel sheet, which forms the substrate. The chemical conversion treatment film is a chemical conversion treatment film containing no chromium at all from the viewpoint of the environment. This chemical conversion coating may be of any composition as long as it ensures the adhesion between the surface of the base material and, when the base material is a galvanized steel sheet, the plating layer and the colored coating film. In addition to these, those that improve corrosion resistance are more preferred.

  From such viewpoints of adhesion and corrosion resistance, an inorganic chemical conversion coating or an inorganic-organic composite chemical conversion coating may be appropriately set as the chemical conversion coating. Specifically, examples of the inorganic chemical conversion coating include one containing at least one selected from a silane coupling agent, silica fine particles, a vanadium compound, a titanium compound, a zirconium compound, a phosphoric acid compound, and the like. On the other hand, as the inorganic / organic composite chemical conversion coating, in addition to the compound contained in the inorganic chemical conversion coating, one or more selected from water-soluble or water-dispersed urethane resins, phenol resins, acrylic resins, polyester resins, and the like are used. What was contained is illustrated.

The silane coupling agent forms a film having a crosslinked siloxane bond as a skeleton by hydrolyzing an alkoxy group into hydroxyl groups and condensing the hydroxyl groups. When there are few alkoxy groups, a crosslinking reaction may be delayed and adhesiveness with a base | substrate may fall. On the other hand, when there are few organic functional groups, adhesiveness with the upper colored coating film may fall. From these points, the silane coupling agent is preferably a trialkoxyl type. Specific examples of silane coupling agents suitable for use in the present invention include, but are not limited to, the following compounds (including common names):
Vinylethoxysilane, vinylmethoxysilane, N- (2-aminomethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminomethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, Tetraethoxysilane, and tetramethoxysilane.

There are two types of silica fine particles, liquid phase silica and gas phase silica, but any of these may be used.
Examples of vanadium compounds include ammonium vanadate and ammonium metavanadate, but are not limited thereto.

  Titanium compounds include Ti alkoxide, basic Ti carbonate, Ti fluoride, Ti-containing organic chelate, Ti-containing coupling agent (Ti alkoxide has an organic functional group such as epoxy group, vinyl group, amino group, methacryloxy group, etc. Examples of such compounds are not limited to these.

  Examples of the zirconium compound include Zr alkoxide, basic Zr carbonate, Zr fluoride, Zr-containing organic chelate and the like, but are not limited thereto.

Examples of the phosphoric acid compound include orthophosphoric acid, pyrophosphoric acid, and polyphosphoric acid, but are not limited thereto.
Further, the amount of adhesion by chemical conversion treatment is 20 mg / m ² or more and 1000 mg / m ² or less for the chemical conversion treatment film of the lower layer of the colored coating film, that is, the chemical conversion treatment film used for the front surface. Corrosion resistance can be ensured. When the amount of adhesion is excessively small, there is not sufficient chemical conversion treatment on the plating surface, and it becomes difficult to develop excellent adhesion. On the other hand, when the adhesion amount is excessively large, the chemical conversion film itself may be coherently broken and the cost is increased.

  On the other hand, regarding the back surface, it is preferable that a chemical conversion treatment film is formed on the surface of the metal plate. What is necessary is just to set suitably the adhesion amount of the chemical conversion treatment film of a back surface according to a use as shown below.

i) Case of having one colored coating film on the chemical conversion treatment film in the same manner as the front surface In this case, good adhesion and corrosion resistance can be ensured by performing the same chemical conversion treatment as the front surface. That is, the preferable adhesion amount in this case is 20 mg / m ² or more and 1000 mg / m ² or less.

It is preferable to use when ii) chemical conversion when the conductivity or the like of only is required, in this case, the deposition amount of the preferred chemical conversion coating, and a 100 mg / ^{m 2} or more 1000 mg / ^{m 2} or less, good High electrical conductivity and corrosion resistance can be secured. When the amount of adhesion is excessively small, the chemical conversion treatment layer on the plating surface does not exist sufficiently, and it becomes difficult to express excellent adhesion. On the other hand, when the adhesion amount is excessively large, the chemical conversion film itself may be coherently broken and the cost is increased. Further, the chemical conversion treatment liquid itself is preferably a system containing the above rust preventive agent in consideration of corrosion resistance, and a system to which a wax or the like is added may be used to ensure pressability.

3. Colored coating The colored coating is composed of other components such as a binder component, a pigment, and resin particles.
(1) Binder component The binder component is composed of a binder resin, which is a resin as a main component of the binder component, a curing agent, and other components. Each component will be described in detail below.

A) Binder resin The binder resin according to this embodiment is a polyester resin whose main resin is water-soluble or water-dispersed, and specifically includes the following two aspects.

i) Polyester resin alone As the binder resin according to this embodiment, a water-soluble or water-dispersed polyester resin may be used alone. The molecular weight is preferably 10,000 to 30,000. If the molecular weight is 10,000 or less, there is a concern that it is difficult to ensure sufficient processability. On the other hand, when the molecular weight exceeds 30000, the bonding site of the resin itself is lowered, so that it is difficult to ensure excellent adhesion with the chemical conversion coating and the crosslinking reaction with a curing agent such as melamine is not sufficiently performed. There is a concern about performance degradation as a film.

ii) Blend resin system having polyester resin as main resin As the binder resin according to this embodiment, a blend resin system having a water-soluble or water-dispersed polyester resin as a main resin may be used. The molecular weight of the water-soluble or water-dispersed polyester resin that is the main resin, that is, the resin that is 60% by mass or more based on the total binder resin, is 10,000 or more and 30,000 or less as in the case of using the resin alone. It is preferable.

  In this blend resin system, examples of resins used as resins other than the main resin (hereinafter referred to as “blend resins”) include urethane resins and epoxy resins. When a urethane resin is used as the blend resin, a preferable urethane-based resin form has an emulsion particle size of 10 nm to 100 nm, and a more preferable range is 20 nm to 60 nm. If the particle size is excessively small, there is a concern that the cost will increase. On the other hand, when the particle size is excessively large, there is a concern that the gap between the emulsions becomes large when a coating is formed, and the barrier property as a coating is lowered. As the type of urethane resin, there are an ether type, a polycarbonate type, an ester type, an acrylic graphite type, etc., but these may be used alone or in combination.

B) Curing agent It is preferable to use a water-soluble curing agent, and specifically, melamine is preferably used. The addition amount of the curing agent is preferably 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin solid content. If the addition amount is less than 5 parts by mass, sufficient crosslinking reaction with the polyester constituting the main resin cannot be expected, and there is a concern that the performance as a coating film becomes insufficient. On the other hand, when the addition amount is more than 30 parts by mass, the crosslinking reaction proceeds excessively, the coating film becomes excessively hard, and there is a concern about deterioration of workability. In addition, as a kind of preferable hardening | curing agent, it is preferable to use the hardening agent with comparatively small surface free energy which is easy to concentrate on the coating-film surface from a viewpoint of coexistence of coating-film processability and coating-film hardness. Specific examples include methylated melamine and butylated melamine.

C) Curing catalyst The binder component according to this embodiment preferably contains a curing catalyst. One of the roles of the curing catalyst is to promote the self-condensation reaction between the curing agents and the crosslinking reaction between the curing agent and the resin. Further, by using methylated melamine or butylated melamine having a small surface free energy, a curing agent is concentrated on the surface of the colored coating film, and a crosslinking reaction and a self-condensation reaction are promoted. For this reason, the colored coating film in the vicinity of the surface is particularly improved in solvent resistance and chemical resistance. Moreover, when the colored coating film contains resin particles to be described later, the hardness of the coating film surface is increased by the hardener concentrated on the surface, and the resin particles are less likely to be lost during press processing.

  Further, the concentration of the curing agent on the surface realizes a configuration in which the surface portion of the colored coating film is hard but the inside of the coating film is relatively soft. For this reason, in addition to being able to achieve both coating film hardness and processability, substances that lower the corrosion resistance of the flat surface of the colored coating, such as moisture, enter the coating in a hard portion of the surface of the colored coating. It is suppressed. In addition, the entire colored coating film can easily follow the deformation of the base material during press working. For this reason, generation | occurrence | production of a crack in a colored coating film is suppressed locally. Accordingly, it is possible to improve the flat portion corrosion resistance, press workability, and coating film hardness in a balanced manner while being a single color coating film.

  As the curing catalyst, dodecylbenzenesulfonic acid or paratoluenesulfonic acid is suitable, and among these catalysts, it is particularly preferable to use an amine-blocked catalyst from the viewpoint of further concentrating the curing agent. The addition amount of the curing catalyst is preferably 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the coating material. When the addition amount is excessively small, there is a concern that the effect as a curing catalyst, that is, the curing is not sufficiently promoted. On the other hand, when the amount added is excessively large, there is a concern that new problems such as occurrence of defects in appearance occur due to excessive progress of crosslinking and the like.

(2) Pigment The pigment contained in the colored coating film according to the present embodiment includes a rust preventive pigment and a colored pigment, and also contains a pigment having other functions such as thermal radiation as necessary.

A) Rust preventive pigment The rust preventive pigment added to the colored coating film is a silica having an oil absorption of 50 ml / 100 g or more and 1000 ml / 100 g or less and an average particle diameter of 10 μm or less. More than 15% by mass is preferable. When other phosphoric acid type rust preventive pigments are used alone without containing this silica, a sufficient corrosion resistance improving effect cannot be obtained when the same addition amount as this silica is added. Further, when a large amount of other rust preventive pigments are added in order to exhibit the same corrosion resistance performance as silica, there are problems that the processability of the coating film itself is impaired and the design property is impaired.

  The reason why the oil absorption of silica is 50 ml / 100 g or more and 1000 ml / 100 g or less is that sufficient corrosion resistance cannot be obtained when the amount is less than 50 ml / 100 g, and the viscosity of the paint increases remarkably when it exceeds 1000 ml / 100 g. It is because it ends. On the other hand, if the average particle size exceeds 10 μm, the possibility of dropping off the pigment increases because it is larger than the film thickness, and there is a concern that the corrosion resistance may be adversely affected. In addition, the minimum of an average particle diameter is not specifically limited.

  An appropriate addition amount of silica having an oil absorption amount in the above range to the coating film is 5% by mass or more and less than 15% by mass with respect to the solid content of the paint, and a more preferable range is 5% by mass with respect to the solid content of the paint. It is less than 10% by mass. If it is less than 5% by mass, a sufficient corrosion resistance effect cannot be obtained, and if it is 15% by mass or more, the workability of the colored coating film is impaired and the amount of the coloring pigment that can be added to the coating film decreases. Impairs design properties, especially concealability and color stability.

  As for the rust preventive pigment, if the color tone stability, concealment property, press workability and the like can be ensured, the oil absorption amount and the average particle diameter of silica other than silica in the above range, other rust preventive pigments, For example, it is possible to use a phosphoric acid-based rust preventive pigment in combination.

B) Colored pigment It is preferable to use an inorganic pigment excellent in low cost, safety, water resistance and weather resistance as a color pigment to be added in order to adjust the color coating film to a specific color tone. Further, when either or both of carbon black and titania pigments are contained in addition to the colored pigment, the thermal radiation property of the colored coating film itself is improved. Therefore, when applying to the housing | casing of the electrical / electronic device by which heat radiation is calculated | required, it is preferable to contain these pigments.

  In addition, when applying to the use by which the designability of a metallic tone etc. is calculated | required, metallic tone can be expressed by adding luster pigments, such as mica and aluminum flakes. The average particle diameter of these bright pigments is preferably about 4 times or less the coating thickness. Moreover, as an addition amount, it is preferable to set it as 20 mass% or less with respect to coating-material solid content.

  In order not to impair the heat dissipation, mica having a relatively high heat radiation property than aluminum flakes is suitable. Note that these bright pigments may be used by blending two types of mica and aluminum flakes depending on the type of metallic tone required.

  The content of these color pigments is preferably 2% by mass or more and 25% by mass or less based on the solid content of the paint. Moreover, it is preferable that it is 7 mass% or more and 40 mass% or less with respect to the coating-material solid content also about the whole pigment. When the pigment content is excessively large, there is a concern that the press workability of the coating film may be significantly reduced. When the pigment content is excessively small, the concealability of the coating film may be impaired or the flat part. There is a concern that the corrosion resistance may decrease.

(3) Other components In addition to the binder component and pigment described above, as a component contained in the colored coating film, leveling agent, resin particles, conductive powder for improving weldability and electromagnetic wave shielding properties, and improving weather resistance Are effective UV absorbers and light stabilizers, waxes effective for improving press workability, and the like, and these may be appropriately contained as necessary.

  Among these, the colored coating film preferably contains resin particles. These resin particles reduce the contact area between the colored coating film and the mold during press processing, improve the lubricity, and prevent the coating film from being damaged by direct contact between the colored coating film and the mold. Have Examples of the resin particles include acrylic resin beads and PTFE resin. Since these resin particles have higher hardness and higher Tg than polyester and urethane resins, which are the main resins, stable lubricity and coating film protection are possible even when the mold becomes hot during continuous pressing. . Although there is no restriction | limiting in particular as an average particle diameter of a resin particle, Preferably it is less than 2 times the coating film thickness. If it is twice or more, the resin particles are likely to be lost during press working. For this reason, possibility that a colored coating film will be damaged and the possibility that it will not pass through a roll gap at the time of painting increase. In addition, regarding acrylic resin and PTFE resin, although depending on press conditions, it is preferable to add two types to the paint. The addition amount of the resin particles is 0.5% by mass or more and less than 15% by mass with respect to the solid content of the paint, and a more preferable range is 1% by mass or more and less than 10% by mass. Further, as a method for improving the lubricity with the mold, a low Tg wax resin such as polyolefin or microcrystalline may be added in addition to the above resin.

(4) Glass transition point temperature of main resin in colored coating film From the viewpoint of maintaining processability, the colored coating film has a glass transition point temperature (Tg) of the main resin in the colored coating film of 30 ° C or lower. Is preferred. On the other hand, with regard to the lower limit of Tg, when Tg is excessively low, there is a concern that the scratch resistance and the like are lowered. For this reason, it is preferable that Tg shall be 0 degreeC or more.

  Tg is measured by the following method. Using a TMA (thermomechanical measuring device), the needle is stabbed in the direction of the coating thickness from the surface of the colored coating that is the measurement target, the temperature is changed at a certain temperature, the change in thermal expansion of the measurement target is measured, and the glass transition The point temperature (Tg) is measured. Thereby, not only the surface of a colored coating film but Tg of a coating-film thickness direction can be measured. There are many specific measurement methods of TMA, for example, differential expansion method TMA is exemplified, but the measured value of Tg does not fluctuate greatly depending on the measurement method, so any method of TMA is used. Also good.

(5) Coating thickness It is preferable that it is the range of 2 micrometers or more and 15 micrometers or less regarding the film thickness of a colored coating film. If it is less than 2 μm, there is a concern that the concealability of the coating film is inferior and the corrosion resistance of the flat surface portion is also lowered, and if it is 15 μm or more, it is disadvantageous in terms of cost.

  In addition, the range of especially preferable coating film thickness changes with the color tone of a colored coating film. For example, in the case of a white coating film (L value of 80 or more), 10 μm or more is particularly preferable in consideration of color stability, concealment properties, etc., and in the range of 10 μm or more and 15 μm or less considering the balance between workability and coating film hardness It is more preferable that On the other hand, a black-based coating (L value is less than 80) has a stable color tone even in a thin film as compared with a white coating, and therefore it is particularly preferably in the range of 2 μm to 10 μm.

4). Solvent / dispersion medium The solvent / dispersion medium in the treatment liquid for forming the chemical conversion coating and the colored coating for forming the colored coating film contains water as a main component. In order to improve the dissolution / dispersion of the solute / dispersoid, an organic solvent having a high solubility in water, such as alcohol, ether, and ketone, may be used together with water. It is preferable to reduce the amount of solvent used as much as possible.

5). Manufacturing method The manufacturing method of the colored coating film which concerns on this embodiment is not specifically limited. First, according to a conventional method, the above-mentioned chemical conversion treatment solution is brought into contact with a substrate and subsequently baked to obtain a metal plate having a chemical conversion treatment film formed on the surface. Examples of specific contact methods between the substrate and the chemical conversion treatment liquid include dipping, spraying, and roll coating. Next, a colored coating obtained by dissolving and dispersing the above-described constituent components in an appropriate medium is applied to the metal plate on which the chemical conversion coating is formed at a predetermined thickness by any method, and the chemical conversion coating is applied. A metal plate having a paint formed thereon is obtained. Specific application methods include dipping, spraying, roll coating, and doctor blade coating. Subsequently, the metal plate on which the coating layer is formed is baked to volatilize the medium and harden the binder component to form a metal plate having a solid colored coating film.

What is necessary is just to select the optimal temperature suitably for the baking temperature of a chemical conversion treatment film and a colored coating film according to the composition of a chemical conversion treatment liquid and a colored coating material, and the characteristic calculated | required.
The baking temperature of the chemical conversion film is 80 ° C. or higher at the PMT (maximum temperature of the substrate). If the film dries, generally the required performance such as sufficient corrosion resistance, conductivity, and film adhesion is obtained. Satisfied.

  On the other hand, the baking temperature of the colored coating film is preferably 170 ° C. or higher in terms of PMT. If it is 170 ° C. or lower, there is a possibility that the colored coating film is in an uncured state because the crosslinking initiation temperature of the coating film is not sufficiently reached.

These baking times may be appropriately selected in consideration of the baking temperature.
In addition, you may apply | coat the clear paint and / or colored paint which have an additional function further on the coated steel plate of this embodiment. By applying such a paint, it is possible to produce a coated steel sheet having the performance of a conventional coated steel sheet and a new performance at a low cost in the conventional 2-coat 2-bake or 3-coat 3-bake coating process. Is possible. Examples of the additional function include, but are not limited to, contamination resistance, deodorization, and deodorization having a photocatalytic function.

6). Press processing Since the coated metal plate provided with the colored coating film of the present embodiment obtained by the above-described process is hard, the colored coating film hardly adheres to the mold in the pressing process. In particular, when the binder component has a curing catalyst, the surface portion is hard and the inside is a relatively soft coating, so that excellent press workability can be stably obtained. Therefore, a housing obtained by pressing a metal plate provided with such a colored coating film has high productivity because it is excellent in shape accuracy and is less likely to be interrupted due to processing defects such as galling. Therefore, the housing | casing which uses the coating metal plate which concerns on this embodiment is excellent also in economical efficiency.

  Further, if the above colored coating is used as the front surface, such a casing is excellent in flat portion corrosion resistance and end surface corrosion resistance and has a hard coating film, and therefore can be suitably used for various applications. Furthermore, if the configuration of the chemical conversion treatment film and / or the colored coating film on the back surface is selected according to the application, it is possible to obtain a housing particularly suitable for each application. Specifically, if a coating film having the same structure as the colored coating film on the front surface is formed on the back surface, both surfaces have good corrosion resistance, so that it can be placed in harsh environments such as outdoors and semi-outdoors. A coated metal plate having a particularly excellent corrosion resistance suitable for the case of the product to be removed can be obtained. On the other hand, if one or two chemical conversion coating layers with conductivity are formed on the back surface, it is a coated metal suitable for housing of home appliances and electronic / electric equipment installed indoors for thin TV applications. A board is obtained.

  Moreover, since a coating film used for a general front surface often has a structure in which a plurality of coating films are laminated on a base material in addition to a chemical conversion treatment film, a coated metal plate provided with such a laminated coating film In comparison, the colored coating film according to the present embodiment has a single-layer structure, and thus the productivity of the coated metal plate is high. Also from this point of view, a casing using such a coated metal plate is excellent in economic efficiency.

  The above description is merely an example of one embodiment of the present invention, and various modifications can be made as long as the basic functions of the present invention can be exhibited.

II. Second Embodiment Subsequently, a second embodiment of the present invention will be described.

  As described above, in the coated metal plate according to the second embodiment, on the premise that the lubricating oil is applied to the surface of the colored coating film at the time of pressing, the characteristics of the colored coating film are not deteriorated by the lubricating oil. Thus, the improvement of press workability by lubricating oil is utilized to the maximum extent.

  As in the case of the coated metal plate according to the first embodiment, apart from the case where the colored coating film has excellent press workability alone, when the coated metal plate has not achieved high press workability, In many cases, a press die is applied while applying a lubricating oil such as quick-drying oil to the surface of the press die and / or the coated metal plate and forming a lubricating layer between the die and the painted metal plate. Moreover, the organic solvent may be apply | coated to the surface for the purpose of washing | cleaning a coating metal plate. In such a case, if the coated metal plate does not have the property of being hardly dissolved in an organic solvent (hereinafter referred to as “solvent resistance”), the surface property of the coated metal plate changes, and the appearance and Mechanical and chemical properties may be deteriorated. For this reason, it is one of the important issues that the coated metal plate has solvent resistance, and the coated metal plate according to the present embodiment is excellent in the solvent resistance.

  The coated metal plate of the present embodiment includes a metal plate, a chemical conversion treatment film comprising one inorganic coating layer or an inorganic / organic composite coating layer formed on at least one surface of the metal plate, and the chemical conversion treatment film. The colored coating film comprises silica having an oil absorption of 50 ml / 100 g or more and 1000 ml / 100 g or less and an average particle diameter of 10 μm or less based on the solid content of the paint. The main resin of the colored coating film is a water-soluble or water-dispersed urethane resin.

  Hereinafter, the description will focus on the colored coating film according to this embodiment, and the base metal plate, chemical conversion coating film, solvent / dispersion medium, manufacturing method, and press working are the same as in the first embodiment. To simplify.

1. Base metal plate The plate-like base material used for the coated metal plate of the present embodiment is not particularly limited as in the first embodiment. Moreover, also about the suitable conditions in the adhesion amount at the time of using a zinc-plated steel plate, and the preferable plating kind according to a use, it is the same as that of 1st embodiment.

2. In the present embodiment, as in the first embodiment, one or more chemical conversion coating layers are formed according to the present invention on both surfaces of a metal plate, for example, a zinc-based plated steel plate, as a base material. The chemical conversion treatment film is a chemical conversion treatment film containing no chromium at all from the viewpoint of the environment. This chemical conversion treatment film may be of any composition as long as it mainly ensures the adhesion between the plating layer and the colored coating film layer when the substrate surface is a zinc-based plated steel sheet. What improves corrosion resistance in addition to adhesiveness is more preferable.

  On the other hand, regarding the back surface, it is preferable that a chemical conversion treatment film is formed on the surface of the metal plate. What is necessary is just to set the adhesion amount of the chemical conversion treatment film of a back surface suitably according to a use like 1st embodiment.

3. Colored coating film The colored coating film according to this embodiment is composed of other components such as a binder component, a pigment, and resin particles in the same manner as the colored coating film according to the first embodiment. The binder component is different from the colored coating film. Therefore, the binder component will be mainly described, and the description of the pigment and other components will be simplified.

(1) Binder component The binder component which concerns on this embodiment is comprised from the binder resin which is a main component of a binder, a hardening | curing agent, and another component similarly to 1st embodiment.

A) Binder Resin The binder resin according to the present embodiment is a water-soluble or water-dispersed urethane resin whose main resin is a water-soluble or water-dispersed urethane resin. As a resin, a water-soluble or water-dispersed polyester resin, a resin system blended with an epoxy resin or the like is included.

  The water-soluble or water-dispersed urethane resin that forms the main resin preferably has a molecular weight of less than 100,000. When the molecular weight is 100,000 or more, there is a concern that it is difficult to ensure excellent adhesion to the chemical conversion coating film because the bonding site of the resin itself is lowered.

  The particle size of the urethane-based resin is not particularly limited, but those having an excessively small particle size are likely to be costly. On the other hand, when the particle size is excessively large, there is a concern that the gap between the emulsions becomes large when a coating is formed, and the barrier property as a coating is lowered. Accordingly, the thickness is preferably 10 nm or more and 100 nm or less, and more preferably 20 nm or more and 60 nm or less.

  The resin type of the urethane resin is not particularly limited, and examples thereof include ether type, polycarbonate type, ester type, and acrylic graphite type. These resins may be used alone or in a blend system. The glass transition temperature Tg of the urethane resin alone is 0 ° C. or lower.

  A preferable form of the water-based polyester resin that can be blended with the urethane resin is a molecular weight of 5000 to 30000, and a more preferable range is 8000 to 25000.

B) Curing agent It is preferable to use a water-soluble curing agent, and specifically, melamine is preferably used. The addition amount of the curing agent is preferably 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin solid content.

C) Curing catalyst The binder component according to this embodiment may contain a curing catalyst. The role of the curing catalyst is to concentrate the curing agent, preferably melamine, on the surface of the colored coating. When the curing agent is concentrated on the surface, the colored coating film in the vicinity of the surface is improved in solvent resistance and chemical resistance. Moreover, when the colored coating film contains resin particles to be described later, the hardness of the coating film surface is increased by the hardener concentrated on the surface, and the resin particles are less likely to be lost during press processing.

  Further, the concentration of the curing agent on the surface realizes a configuration in which the surface portion of the colored coating film is hard but the inside of the coating film is relatively soft. For this reason, in addition to being able to achieve both coating film hardness and processability, substances that lower the corrosion resistance of the flat surface of the colored coating, such as moisture, enter the coating in a hard portion of the surface of the colored coating. When oil is applied to improve pressability during press working, the sliding resistance is prevented from increasing, and the press oil enters the surface of the paint film and damages the colored paint film. Suppress. Accordingly, it is possible to improve the flat portion corrosion resistance, press workability, and coating film hardness in a balanced manner while being a single color coating film.

From the viewpoint of obtaining the above effect while suppressing the occurrence of defects in appearance, the addition amount of the curing catalyst is preferably 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the colored paint.
Moreover, in the colored coating film which concerns on 2nd embodiment, compared with the colored coating film which concerns on 1st embodiment, the hardening of the surface part by a curing catalyst tends to advance as a general tendency. If this hardening proceeds excessively, the surface portion cannot follow the deformation of the base metal plate during secondary processing such as press processing, and cracking of the colored coating film may occur. Therefore, compared with the case of 1st embodiment, it is especially preferable to set the addition amount of a curing catalyst low rather than depending on the kind. Specifically, it is particularly preferably 0.1 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the paint.

  As in the first embodiment, dodecylbenzenesulfonic acid or paratoluenesulfonic acid is suitable as the curing catalyst. For these catalysts, amine-blocked catalysts may be used.

(2) Pigment Similarly to the first embodiment, the pigment contained in the colored coating film according to the present embodiment includes a rust preventive pigment and a colored pigment, and has other functions such as thermal radiation as necessary. Pigments are also included. The types and contents of suitable rust preventive pigments and color pigments are the same as in the first embodiment. That is, from the viewpoint of improving the corrosion resistance of the surface of the colored coating film, silica having an oil absorption of 50 ml / 100 g or more and 1000 ml / 100 g or less and an average particle diameter of 10 μm or less is 5% by mass or more and 15% by weight based on the solid content of the paint. Contains less than mass%.

(3) Other components As components contained in the colored coating film, in addition to the binder component and pigment described above, leveling agent, resin particles, conductive powder for improving weldability and electromagnetic wave shielding properties, and improving weather resistance Examples thereof include an ultraviolet absorber and a light stabilizer effective for the treatment, and a wax effective for improving the press workability, and these may be appropriately contained as necessary. Among these, it is preferable that the colored coating film contains resin particles as in the first embodiment, and the types, types, and contents of suitable resin particles are the same as in the first embodiment.

(4) Glass transition temperature of main resin in colored coating film From the viewpoint of maintaining processability, the colored coating film preferably has a glass transition temperature (Tg) of the main resin in the coating film of 0 ° C. or lower. More preferably, it is −10 ° C. or lower. On the other hand, the lower limit of Tg is not particularly limited, but the Tg of materials that are generally available on the market is −35 ° C. or higher.

(5) Coating thickness It is preferable that it is the range of 2 micrometers or more and 15 micrometers or less regarding the film thickness of a colored coating film. If it is less than 2 μm, there is a concern that the concealability of the coating film is inferior and the corrosion resistance of the flat surface portion is also lowered, and if it is 15 μm or more, it is disadvantageous in terms of cost.

  In addition, the range of especially preferable coating film thickness changes with the color tone of a colored coating film. For example, in the case of a white coating film (L value of 80 or more), 10 μm or more is particularly preferable in consideration of color stability, concealment properties, etc., and in the range of 10 μm or more and 15 μm or less considering the balance between workability and coating film hardness It is more preferable that On the other hand, a black-based coating (L value is less than 80) has a stable color tone even in a thin film as compared with a white coating, and therefore it is particularly preferably in the range of 2 μm to 10 μm.

4). Solvent / dispersion medium The treatment liquid for forming the chemical conversion treatment film and the solvent / dispersion medium in the colored paint for forming the colored coating film contain water as a main component, as in the first embodiment. Similar to the first embodiment, an organic solvent having high solubility in water may be used in order to improve the dissolution / dispersion of the solute / dispersoid.

5). Production Method As in the first embodiment, the production method of the colored coating film according to this embodiment is not particularly limited. Moreover, since the suitable conditions of the baking temperature of a chemical conversion treatment film and a colored coating film are the same as that of 1st embodiment, description is abbreviate | omitted.

6). Press processing Since the coated metal plate provided with the colored coating film of the present embodiment has excellent solvent resistance, it is not necessary to limit the amount of lubricating oil used in press processing. For this reason, it is hard to produce the interruption of production by generation | occurrence | production of a process defect, for example, a galling phenomenon, in press work. Therefore, a press-processed product such as a casing using the coated metal plate according to the present invention has high productivity and is less likely to deteriorate in shape accuracy. Therefore, by using the coated steel plate according to the present embodiment, it is possible to provide a casing having excellent quality and economy.

  Further, when the above colored coating is used as the front surface, the casing is excellent in flat surface portion corrosion resistance and end surface corrosion resistance, and thus can be suitably used for various applications. In particular, as in the first embodiment, if the back surface is appropriately selected, it is possible to obtain a housing suitable for outdoor use, or a housing suitable for home appliances and electronic / electric equipment.

Furthermore, since it is a comparatively simple coating-film structure similarly to 1st embodiment, the housing | casing which concerns on this embodiment is excellent also from this viewpoint.
The above description is merely an example of one embodiment of the present invention, and various modifications can be made within the scope of the claims.

1. Production of Steel Plate Samples Three types of alloyed hot dip galvanized steel plate (GA), electrogalvanized steel plate (EG), and hot dip galvanized steel plate (GI) shown below were used as the galvanized steel plate of the base material. All the steel plates were 250 × 300 mm in size.

i) GA: Plating adhesion amount (per one side): 30 g / m ²
ii) EG: Amount of plating adhesion (per one side): 20 g / m ²
iii) GI: Amount of plating adhesion (per one side): 45 g / m ² .
After performing alkali degreasing and water washing on both surfaces of each substrate-plated steel sheet according to a conventional method, the following steps were performed to prepare a coated steel sheet.

(1) Chemical conversion solution About the chemical conversion solution, a commercially available chemical solution (EC2330 manufactured by Nippon Paint Co., Ltd.) was used. This chemical solution is an inorganic-organic composite chemical conversion treatment solution containing a silane coupling agent, vapor phase silica, a V-based compound, a Zr-based compound, a urethane resin, and the like.

(2) Colored paint The water-dispersed or water-soluble resin used is as shown in Table 1.

  These resins were blended singly or in combination, and a melamine-based curing agent (Summar M-50W manufactured by Sumitomo Chemical Co., Ltd.) was further added to produce a base resin shown in Table 2.

  Various pigments and the like were added to the base resin described in Table 2 to prepare paints described in Table 3.

In any of the above paints, 0.2 g of a curing catalyst (Mitsui Cytec Catalyst 4050) was added to 100 g of the paint.
In addition, the display in the column of the pigment etc. of Table 3 means the following component.

A) Silica: Silo mask (Ca 0% type) manufactured by Fuji Silysia Chemical Co., Ltd., oil absorption of 100 ml / 100 g or more, average particle size of 2.09 μm,
B) Tripoly: Condensed aluminum phosphate K-WHITE G105 manufactured by Teika Co., Ltd., oil absorption of less than 100 ml / 100 g,
C) RINMAG: Toho Pigment Industries Co., Ltd. Magnes Phosphite EXPERT NP-1020, oil absorption less than 100ml / 100g,
D) Beads: acrylic resin beads having an average particle diameter of 8 μm,
E) CB: carbon black MA100 manufactured by Mitsubishi Chemical Corporation
F) Titania: Ishihara Sangyo Co., Ltd. Titania Typec CR95,
G) Mica: Mica having an average particle size of 8 μm,
H) Aluminum: Aluminum flakes with an average particle size of 10 μm,
I) Wax: PTFE, polyethylene wax blended 1: 1 (non-volatile content 40%).
Moreover, the column of PWC indicates the content (unit: mass%) with respect to the solid content of the paint such as these pigments.

(3) Preparation of front surface (design surface) sample The above chemical conversion treatment solution was prepared and applied onto a plated steel plate using a bar coater, and the maximum temperature (PMT) of the plate was 80 ° C. in 10 seconds. And a chemical conversion treatment film on the front surface was formed.

  Next, using the colored paint described in Table 3, it was applied to the steel plate sample on which the chemical conversion film was formed, using a bar coater, and heated so that the ultimate temperature of the plate reached 180 ° C. in 50 seconds. A top coat film on the surface was formed. The film thickness was adjusted by adding a solvent and changing the bar coater count to obtain a film thickness of 8 μm.

2. Evaluation Method (1) Slidability As a substitute characteristic of press workability, the slidability of the coating film was evaluated using a pin-on-disk type wear tester. The test conditions were as follows:
Pin tip shape: spherical shape with a radius of 3/16 inch,
Pin contact position on the disc: 10 mm from the center,
Temperature: 75 ° C
Weight: 30N,
Rotation speed: 1rpm,
Number of revolutions: 15 laps.

The disc surface after being rotated 15 times was visually observed and evaluated according to the following criteria. ○ passed:
○: No galling
X: There is a coating galling.
The term “coating galling” refers to a state in which the surface properties of the sliding surface have been remarkably lowered due to adhesion of the coating film to pins, local cracking of the coating film, or the like.

(2) Corrosion resistance Four sides of the 70 mm × 150 mm test side were sealed, a salt spray test was performed under the conditions specified in JIS 2371, and the corrosion area ratio of the flat portion of the sample after the test was determined and evaluated. The judgment criteria are as follows, and ◎ and ○ were accepted:
◎: No white rust after 240 hours,
○: No white rust occurs after 120 hours,
×: White rust generated after 120 hours.

(3) Bending Workability A 0T bending test (23 ° C.) was performed on the test piece, and the presence or absence of cracks in the 180 ° adhesion bending coating film was examined using a 10 × loupe. The evaluation criteria are as follows, and ○ was accepted:
○: No crack,
X: There is a crack.

(4) Solvent resistance A felt soaked with various solvents was slid 100 times with a load of 1 kg, and the state of the felt and the coating film after sliding was visually observed. Judgment criteria are as follows, and ○ was accepted:
○: Dissolution of the coating film is not observed,
X: Dissolution of the coating film is not observed.

3. Evaluation Results Tables 4 and 5 show the evaluation results.

Claims (10)

  A metal plate, a chemical conversion coating formed of at least one inorganic coating layer or inorganic-organic composite coating layer formed on at least one surface of the metal plate, and a single color coating formed on the chemical conversion coating The colored coating film is provided with a silica having an oil absorption of 50 ml / 100 g or more and 1000 ml / 100 g or less and an average particle size of 10 μm or less of 5% by mass or more and less than 15% by mass with respect to the solid content of the paint. A coated metal plate comprising: a colored resin film, wherein the main resin of the colored coating film is a water-soluble or water-dispersed polyester resin or urethane resin.   2. The coated steel sheet according to claim 1, wherein the total amount of the pigment in the colored coating film is 7% by mass or more and 40% by mass or less based on the solid content of the paint.   The coated steel sheet according to claim 1 or 2, wherein a thickness of the colored coating film is 2 µm or more and 10 µm or less.   The main resin of the colored coating is a water-soluble or water-dispersed polyester resin, the glass transition temperature of the main resin in the colored coating is 0 ° C. or higher and 30 ° C. or lower, and the molecular weight is 10,000 or higher and 30000 or lower. The coated steel plate according to any one of claims 1 to 3.   The main resin of the colored coating film is a water-soluble or water-dispersed polyester resin, and the coating for forming the colored coating film is cured in an amount of 0.1 to 2 parts by mass with respect to 100 parts by mass of the paint. The coated steel sheet according to any one of claims 1 to 4, comprising a catalyst.   The main resin of the colored coating film is a water-soluble or water-dispersed urethane resin, and the glass transition temperature of the main resin in the colored coating film is 0 ° C. or less and the molecular weight is less than 100,000. The coated steel plate in any one of Claims 1-3.   The colored coating film contains water-soluble melamine as a curing agent in an amount of 5% by mass to 30% by mass with respect to the resin solid content, and a curing catalyst in an amount of 0.1 to 2 parts by mass with respect to 100 parts by mass of the colored paint. The coated steel sheet according to any one of claims 1 to 6, further comprising: The coated steel sheet according to any one of claims 1 to 7, wherein an adhesion amount of a film formed by the inorganic coating or the inorganic-organic composite coating is 20 mg / m ² or more and 1000 mg / m ² or less.   The coated steel sheet according to any one of claims 1 to 8, wherein the metal plate is a plated steel sheet containing zinc.   A housing comprising the coated metal plate according to any one of claims 1 to 9 so that a surface on which a colored coating film is formed is on an outer side.