KR101500838B1 - Thin-black-layer-coated metal sheet - Google Patents

Abstract

In the thin film black coated metal sheet of the present invention, a first black layer formed of a water-based black resin composition containing surface-treated carbon black whose surface is coated with an aqueous resin is laminated on at least one surface of a metal sheet is 0.4 to 1.0 m , And a second black layer having a thickness of 1.4 to 9 m formed from a solvent-based black paint is laminated on the first black layer. In the thin film black-coated metal sheet of the present invention, the total coating film is sufficiently thin, and also exhibits good blackness and no appearance defect.

Description

THIN-BLACK-LAYER-COATED METAL SHEET [0002]

The present invention relates to a thin film black-coated metal plate having good blackness.

Conventionally, black plastic has been used as a back cover of a thin television such as a liquid crystal television or a plasma television. In recent years, from the viewpoint of imparting conductivity (electromagnetic wave countermeasure) to the inner side, a steel plate coated with a black coating film (PCM: precoat PreCoated) metal) is being replaced.

In the coated steel sheet (PCM) so far, in order to hide the appearance and gloss of the original plate (electro-galvanized steel sheet, hot-dip galvanized steel sheet, galvannealed steel sheet, etc.) (Coating amount: about 12 g / m < ² >). Further, under the black coat layer (top coat layer), a primer coat layer the degree of 3μm: there is just installed to a thickness of (coating weight of about 5g / m ²⁾ in this way, in conventional PCM, the total thickness of the topcoat layer and the primer coating layer was not normal is set to a thickness of about 10~20μm However, if the thickness of the coating film is too large, the amount of the coating material used increases, and the time for coating and baking becomes longer, resulting in an increase in manufacturing cost. Depending on the intensification of competition in all markets, during the compression, reduction of manufacturing costs higher demands, there is a need for a thin coating of at PCM.

As a coated steel sheet (PCM) aiming at thinning, for example, there is a method in which an undercoating film is formed on one side of a steel sheet, and an upper coating film, which is an organic resin coating film containing scaly substances, is formed on the undercoating film A coated steel sheet having a total film thickness of 10 탆 or less has been proposed (JP-A-2008-55774). And a lower layer coating film comprising porous silica as a coloring pigment and a rustproof pigment, wherein the thickness of the outermost layer coating film is 2 占 퐉 or more, the thickness of the lower layer coating film is 2 占 퐉 or more, A coated steel sheet having a coating film thickness of 10 탆 or less has also been proposed (Japanese Patent Laid-Open No. 2010-115902).

However, in general, as the thickness of the coating film of PCM is made thinner, the degree of blackness is lowered, and appearance of strong blackish brown (large b value) or appearance of strong blackish-black color (large L value) tends to occur. Even in the above two prior art coated steel sheets, the blackness is improved by inclusion of flaky substances, but the blackness (for example, the L value is 20 or less) It was the phenomenon not to reach.

Therefore, the present inventors have found that a coated steel sheet capable of exhibiting good blackness even when the thickness of the black coating film is small, is a coated steel sheet having a film thickness of about 0.3 to 1.5 (Japanese Unexamined Patent Application Publication No. 2011-224972). This coated steel sheet can achieve an excellent level of blackness of 20 or less in L value, and is very advantageous from the viewpoint of reducing manufacturing cost because the coating film is very thin, about 0.3 to 1.5 m. On the other hand, on the other hand, in actual production, since the black coating is too thin, coating defects due to coating unevenness, dust on the production line, and the like are liable to occur, resulting in appearance failure, which may impair the design of the coated steel sheet . Particularly, in this prior art, although the characteristics such as corrosion resistance and scratch resistance are expressed by providing a clear coat on the black coat, if such a clear coat is present, coating film defects such as coating unevenness and dust are promoted, As shown in FIG.

Japanese Patent Application Laid-Open No. 2008-55774 Japanese Patent Application Laid-Open No. 2010-115902 Japanese Patent Application Laid-Open No. 2011-224972

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thin film-coated metal plate which is sufficiently thin, exhibits good blackness and has no defective appearance.

The thin black paint-coated metal sheet of the present invention, which can solve the above problems, is characterized in that a first black layer formed of a water-based black resin composition and having a thickness of 0.4 to 1.0 m is laminated on at least one surface of a metal sheet, And a second black layer having a thickness of 1.4 to 9 m formed from a solvent-based black paint are laminated. The water-based black resin composition contains surface-treated carbon black whose surface is coated with an aqueous resin.

In the present invention, it is preferable that the content of the surface-treated carbon black (solid content) is 10 to 40 mass% in 100 mass% of the total solid content of the aqueous black resin composition.

In a preferred embodiment of the present invention, the blackness (L value) of the surface of the first black layer is 25 or less and the b value is 3 or less.

In the present invention, when the solvent-based black paint contains resin particles and the particle diameter of the resin particles is 14 占 퐉 or less and the film thickness of the second black layer is t (占 퐉), t (占 퐉) μm) or less.

In a preferred embodiment of the present invention, the solvent-based black paint contains resin particles having a particle diameter of 14 탆 or less, and the blackness (L value) of the surface of the second black layer laminated on the first black layer is 20 or less , And the b value is 1.5 or less.

In the present invention, it is preferable that the aqueous black resin composition contains a binder resin, and the binder resin is an olefin-α, β-unsaturated carboxylic acid copolymer, an α, β-unsaturated carboxylic acid polymer, an oxazoline group- Ammonium, and the content of the crosslinking agent is 2 to 19 parts by mass based on 100 parts by mass of the total amount of the olefin-?,? -Unsaturated carboxylic acid copolymer and?,? - unsaturated carboxylic acid polymer, and the content of the crosslinking agent The content is preferably 30 to 85% by mass in 100% by mass of the total solid content of the water-based black resin composition.

In the present invention, it is preferable that the aqueous black resin composition further contains colloidal silica, and the content of the colloidal silica is 5 to 30% by mass of 100% by mass of the total solid content in the aqueous black resin composition.

In the present invention, it is preferable that the aqueous black resin composition contains a silane coupling system of 5 to 25 parts by mass based on 100 parts by mass of the total solid content of the surface-treated carbon black, the binder resin and the colloidal silica.

In the present specification, the term "total solid content in the aqueous black resin composition" means the total solid content of the surface-treated carbon black, the binder resin and the colloidal silica.

According to the present invention, a first black layer formed from a water-based black resin composition containing a surface-treated carbon black whose surface is coated with an aqueous resin and a second black layer formed from a solvent- It is possible to provide a thin film black coated metal plate having good appearance because it is laminated with a predetermined thickness so that good blackness is exhibited even when the total coating film is sufficiently thin and coating defects such as coating unevenness and dust are not easily noticeable have.

1 is a view showing the relationship between the film thickness of the second black layer and the blackness (L value) of the black metal plate in the thin film black-coated metal plate (using the undercoat metal plate EG) of Example 1 and Comparative Example 1 .
2 is a graph showing the relationship between the film thickness of the second black layer and the blackness (L value) of the black metal plate in the thin film black-coated metal plate (using the undercoat metal plate GI) of Example 1 and Comparative Example 1 .
Fig. 3 is a graph showing the relationship between the film thickness of the second black layer and the b value of the black metal plate in the thin black-coated black plate (using the under-treated black plate EG) of Example 1 and Comparative Example 1. Fig.
Fig. 4 is a graph showing the relationship between the film thickness of the second black layer and the b value of the black metal plate in the thin-film black-coated metal plate (using the under-treated metal plate GI) of Example 1 and Comparative Example 1. Fig.

The thin black paint-coated metal sheet of the present invention (hereinafter sometimes simply referred to as a "black metal sheet") is formed from a water-based black resin composition containing at least one surface of a metal sheet a surface-treated carbon black whose surface is coated with an aqueous resin A first black layer is laminated on the first black layer, and a second black layer formed from a solvent-based black paint is laminated on the first black layer. Hereinafter, the black metal plate of the present invention will be described in detail.

(plate)

The metal plate used in the present invention is not particularly limited as long as it is used as a precoated metal plate. For example, an aluminum plate, a titanium plate, and the like can be used in addition to steel sheets such as unplated cold rolled steel sheets, hot dip galvanized steel sheets (GI), galvannealed galvanized steel sheets (GA), and electro galvanized steel sheets (EG). Among them, a hot-dip galvanized steel sheet (GI), an electrogalvanized steel sheet (EG), an aluminum sheet and a titanium sheet are preferable.

It is preferable that the metal plate has a base layer formed on at least one side thereof by a pretreatment process in advance. For example, if a chemical conversion coating layer (base portion) formed by a ground treatment is provided on the surface of the metal plate on the side forming the first black layer to be described later, adhesion between the metal plate and the first black layer is improved.

Examples of the chemical conversion coating layer (base layer) include an organic coating layer, an inorganic coating layer, a phosphate coating layer, and a chromate coating layer. Of these, an organic coating layer, an inorganic coating layer and a phosphate coating layer are preferable. As the organic coating layer, it is preferable to appropriately select and use, for example, a polyethylene resin, an epoxy resin, an acrylic resin, a urethane resin, a polyester resin, a fluorine resin, a mixture thereof, a copolymer and a modified resin. Silica gel, colloidal silica or the like may be further added to the organic film for the purpose of improving the corrosion resistance or a small amount of various wax components may be added for the purpose of improving workability after application of the coating film, A coupling agent may be added. Examples of the inorganic coating layer include a silicate coating layer, and phosphoric acid or fluoride may be added to the silicate coating.

The adhesion amount of the chemical conversion coating layer (base layer) is not particularly specified, but it is preferably 50 mg / m ² or more in terms of dry weight from the viewpoint of corrosion resistance if it is an organic coating layer or an inorganic coating layer. However, if it exceeds 150 mg / m ² , the effect of improving the corrosion resistance is saturated and the manufacturing cost is increased.

A particularly preferable embodiment of the metal plate on which the undercoat layer is formed is a method for manufacturing a metal plate (hereinafter sometimes referred to as a " specific undercoat composition ") comprising a metal plate made of galvanized aluminum, colloidal silica and polyacrylic acid And dried. When the specific under-treatment composition is applied to a zinc-plated metal plate, the surface of the metal plate is etched by the hydrogen ions derived from the aluminum acid in the process, and the interaction between the aluminum ion originating from the aluminum acid and the colloidal silica, It is possible to form an insoluble film having excellent adhesion with the black layer. As a result, the film adhesion after bending or press working (after elongation / shrinkage deformation) is improved and the corrosion resistance and the tape peeling resistance are significantly improved .

The content ratio of the aluminum acid and the colloidal silica in the specific under-treatment composition is preferably in the range of 30:70 to 70:30 (more preferably 35:65 to 65:50) in terms of the solid content ratio of aluminum aluminum: colloidal silica (weight ratio) : 35, more preferably 45:55 to 65:35). When the amount of the colloidal silica is larger than the above ratio, the film-forming property is lowered to make it difficult for the undercoat layer to be formed, and the effect of improving the corrosion resistance and the adhesion with the top coat is hardly obtained. Furthermore, . On the other hand, if the ratio of the colloidal silica is less than the above ratio, the proportion of the aluminum acid in the composition increases, so that the proportion of the aluminum remaining in the water which has not been reacted (etched) with the metal plate is dissolved in the water increases, May be lowered.

Among the above specific undercoat compositions, the polyacrylic acid is preferably contained in an amount of 0.1 to 5 parts by mass (more preferably 0.2 parts by mass or more and 3 parts by mass or less) based on 100 parts by mass of the total solid content of the aluminum acid and colloidal silica in the process Do. Polyacrylic acid is considered to have a function of appropriately controlling the reaction (etching) between the metal plate surface (galvanized) and aluminum aluminum undergone galvanizing and the like, and when it is less than the above range, excessive etching occurs, If the amount is larger than the above range, on the other hand, the etching becomes insufficient, and the insoluble film formed by the aluminum aluminum and the colloidal silica in the film is not sufficiently formed, thereby making it difficult to obtain the effect of improving the adhesion and corrosion resistance.

The silane coupling agent is further added in an amount of 3 to 15 parts by mass (more preferably 5 parts by mass or more and 12.5 parts by mass or less) based on 100 parts by mass of the total solids of aluminum oxide and colloidal silica in the composition, It is also preferable to contain them. When the amount of the silane coupling agent is less than the above range, the effect of improving the adhesion and corrosion resistance to the top coat and the metal sheet tends to become insufficient, resulting in peeling of the film under more severe processing conditions. On the contrary, , There is a possibility that the corrosion resistance and the adhesion are also lowered.

(First black layer)

The first black layer laminated on at least one surface of the metal sheet is formed from a water-based black resin composition.

<Surface-treated carbon black>

The water-based black resin composition contains surface-treated carbon black whose surface is coated with an aqueous resin as a black pigment. In the case of ordinary carbon black whose surface is not coated with a water-based resin, secondary aggregation tends to occur due to changes in pH or compatibility with a binder resin when mixed with a binder resin described later, and as a result, When the surface-treated carbon black whose surface is coated with an aqueous resin exhibits excellent dispersibility when mixed with the binder resin, secondary aggregation is difficult to occur, so that the first black layer formed of the water- And exhibits a sufficiently high blackness even with a thin film thickness.

In the present specification, the term "surface-treated carbon black coated with a water-based resin" includes not only a surface in which the entire surface of the carbon black is coated with an aqueous resin but also a part in which the surface is covered.

The carbon black constituting the surface-treated carbon black is not particularly limited, and examples thereof include carbon black, sand bar, commercially available carbon black for coloring and carbon black for rubber. The water-based resin covering the surface of the carbon black is not particularly limited as long as it can prevent secondary aggregation of carbon black, and examples thereof include gelatin, polyvinyl alcohol, polyvinylpyrrolidone, water-soluble acrylic resin, polyacrylamide , Polyvinylpyridine, polyacrylic acid, and the like. The amount (coating amount) of the water-based resin is preferably 5 parts by mass or more and 380 parts by mass or less based on 100 parts by mass of the carbon black. The surface-treated carbon black may further contain a surfactant. This makes it possible to further suppress secondary agglomeration of the surface-treated carbon black in the binder resin. Examples of such surfactants include known anionic, nonionic, and cationic surfactants.

As the surface-treated carbon black, for example, it is preferable to use a high concentration mink (ink) used in a calligraphy. The siloxane is an aqueous dispersion containing surface-treated carbon black. For example, the surface of an indeterminate furnace black produced by a furnace method or the like which incompletely combusts a petroleum or coal-based oil in a high temperature gas is coated with a water- A glycol-based cryoprotectant and a preservative, and mixing and slurrying the mixture. For example, commercially available inks (e.g., &quot; Super Mackerel BA-8 &quot;, made by Kuretake Co., Ltd., etc.) may be used. On the other hand, the surface-treated carbon black or an aqueous dispersion thereof may be prepared based on a known method (for example, Japanese Patent Application Laid-Open No. 1995-188597 or Japanese Patent Laid-Open Publication No. 1994-234946). The surface-treated carbon black (or an aqueous dispersion thereof) may be used alone or in combination of two or more.

The surface-treated carbon black (its solid content in the case of using the aqueous dispersion of surface-treated carbon black) is preferably 10 mass% or more (more preferably 20 mass% or more) of 100 mass% , Preferably not more than 40 mass% (more preferably not more than 30 mass%). When the content of the surface-treated carbon black is less than 10 mass%, the L value and the b value of the first black layer become high, and as a result, the L value and the b value of the black metal plate obtained by laminating the second black layer become high, And a sufficient blackness can not be expressed (see Figs. 1 to 4). On the other hand, when the content of the surface-treated carbon black exceeds 40% by mass, the resin component serving as a binder contained in the composition is relatively decreased, so that the adhesion between the first black layer and the second black layer is lowered, Gelation tends to occur, and the liquid-phase stability of the aqueous black resin composition may be deteriorated. When the content of the surface-treated carbon black is within the above range, it is difficult for the surface-treated carbon black to cohere with the binder resin even when mixed with the binder resin, and high dispersion stability can be maintained.

<Binder Resin>

The water-based black resin composition usually includes a binder resin for fixing the surface-treated carbon black in the first black layer formed from the composition. The binder resin is not particularly limited as long as it can fix the surface-treated carbon black, but polyethylene resin, polyurethane resin or the like can effectively suppress the secondary agglomeration of the surface-treated carbon black in the composition, Is preferable in that excellent liquid stability can be obtained. Particularly preferably, it is a polyethylene resin. The binder resin may be used alone or in combination of two or more.

The polyethylene resin may be an olefin-α, β-unsaturated carboxylic acid copolymer (hereinafter sometimes referred to as "olefin-acid copolymer") and an α, β-unsaturated carboxylic acid polymer (hereinafter sometimes referred to as "carboxylic acid polymer" ), And a crosslinking agent selected from an oxazoline group-containing polymer and zirconium ammonium carbonate. The olefin-acid copolymer and the carboxylic acid polymer improve the compatibility with the carbon black and improve the adhesion between the first black layer and the metal sheet without impairing the dispersion stability of the surface-treated carbon black in the aqueous black resin composition . Further, the crosslinking agent selected from the oxazoline group-containing polymer and the zirconium ammonium carbonate crosslinks with the olefin-acid copolymer and the carboxylic acid polymer to form a dense and very hard black layer, thereby improving the scratch resistance of the second black layer . Particularly, since zirconium carbonate is highly reactive and has excellent flowability at the time of film formation, the effect as a cross-linking agent is more significant, and an excellent effect is also exerted on the abrasion resistance of the sand.

On the other hand, the "olefin-acid copolymer" in the present invention is a copolymer of an olefin and an α, β-unsaturated carboxylic acid, and the constituent unit derived from olefin is contained in the copolymer in an amount of 50 mass% And the constituent unit derived from the unsaturated carboxylic acid is 50 mass% or less). The "carboxylic acid polymer" is a polymer (including a copolymer) obtained by polymerizing an α, β-unsaturated carboxylic acid as a monomer, and the constituent unit derived from an α, β-unsaturated carboxylic acid is preferably 90 mass% or more in the polymer Do.

The olefin-acid copolymer can be produced by copolymerizing an olefin with an?,? - unsaturated carboxylic acid by a known method, and is also commercially available. The olefin-acid copolymers may be used alone or in combination of two or more.

The olefins usable for the production of the olefin-acid copolymer are not particularly limited, but ethylene, propylene and the like are preferable, and ethylene is more preferable. In the olefin-acid copolymer, the olefin constituent unit may be derived from only one kind of olefin, or may be derived from two or more kinds of olefins.

The?,? - unsaturated carboxylic acid which can be used in the production of the olefin-acid copolymer is not particularly limited, and examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and isocrotonic acid; And dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. Of these, acrylic acid is preferred. In the olefin-acid copolymer, the constituent unit of the?,? - unsaturated carboxylic acid may be derived from only one?,? - unsaturated carboxylic acid, or may be derived from two or more?,? - unsaturated carboxylic acids.

The alpha, beta -unsaturated carboxylic acid unit in the olefin-acid copolymer has the function of improving the adhesion between the first black layer and the metal plate. In order to effectively exhibit such an action, the amount of the alpha, beta -unsaturated carboxylic acid unit Is preferably 5 mass% or more, and more preferably 10 mass% or more. On the other hand, the upper limit of the amount of the?,? - unsaturated carboxylic acid unit in the copolymer is 50 mass% as described above, but is preferably 30 mass% or less, more preferably 25 mass% or less, from the viewpoint of corrosion resistance.

The olefin-acid copolymer may have a constituent unit derived from other monomers within a range not adversely affecting the secondary aggregation inhibition of the surface-treated carbon black. In the olefin-acid copolymer, the amount of the constituent unit derived from the other monomer is preferably 10% by mass or less, more preferably 5% by mass or less, and the most preferred olefin-acid copolymer is olefin- ,? -unsaturated carboxylic acid. Preferred olefin-acid copolymers include ethylene-acrylic acid copolymers.

The weight average molecular weight (Mw) of the olefin-acid copolymer in terms of polystyrene is preferably 1,000 to 100,000, more preferably 3,000 to 70,000, and still more preferably 5,000 to 3,000. This Mw can be measured by GPC using polystyrene as a standard.

Examples of the carboxylic acid polymer include homopolymers or copolymers of one or more?,? - unsaturated carboxylic acids, or copolymers obtained by further copolymerizing other monomers (excluding olefins). Such a carboxylic acid polymer can be produced by a known method and is also commercially available. The carboxylic acid polymer may be used alone or in combination of two or more.

As the?,? - unsaturated carboxylic acid which can be used for the production of the carboxylic acid polymer, any of the?,? - unsaturated carboxylic acids exemplified for use in the synthesis of the olefin-acid copolymer can be used. Of these, acrylic acid and maleic acid are preferable, and maleic acid is more preferable.

The carboxylic acid polymer may contain a constituent unit derived from a monomer other than the?,? - unsaturated carboxylic acid, but the amount of the constituent unit derived from the other monomer is 10 mass% or less, preferably 5 mass% or less , and a carboxylic acid polymer composed solely of?,? - unsaturated carboxylic acid is more preferable.

Preferred examples of the carboxylic acid polymer include polyacrylic acid, polymethacrylic acid, acrylic acid-maleic acid copolymer, and polymaleic acid. Of these, polymaleic acid is more preferable from the viewpoint of the first black layer adhesion and the like. Since the amount of the carboxyl group is large in the polymaleic acid, the adhesion between the first black layer and the metal plate is further improved.

The weight average molecular weight (Mw) of the carboxylic acid polymer is preferably 500 to 30,000, more preferably 800 to 10,000, more preferably 900 to 3,000, and most preferably 1,000 to 2,000 in terms of polystyrene. This Mw can be measured by GPC using polystyrene as a standard.

The content (mass ratio) of the olefin-acid copolymer and the carboxylic acid polymer in the polyethylene resin is preferably 1,000: 1 to 10: 1, more preferably 200: 1 to 20: 1, 25: 1. If the content of the carboxylic acid polymer is too low, the effect of combining the olefin-acid copolymer and the carboxylic acid polymer may not be sufficiently exhibited. Conversely, if the content of the carboxylic acid polymer is excessive, the olefin- The carboxylic acid polymer is phase-separated and the first black layer may not be uniformly formed.

The oxazoline group-containing polymer has an oxazoline group, and the oxazoline group is cross-linked with the carboxyl group of the olefin-acid copolymer or the carboxylic acid polymer, whereby the resins cross each other to form a dense network structure. This improves the toughness of the first black layer.

As the oxazoline group-containing polymer, it is preferable that the main chain is made of styrene / acrylic in view of improving the hardness of the black layer and improving the brittleness of the black layer. For example, "Epocros (registered trademark)" available from Nippon Shokubai Co., Ltd. is suitably used. K-2010E (Tg: -50 占 폚), K-2020E (Tg: 0 占 폚) is preferable as the "Epochros (registered trademark) ) And K-2030E (Tg: 50 DEG C). Among them, "Epochros (registered trademark) K-2030E" is most preferable in that a harder film can be obtained.

The carbon dioxide and ammonium are desorbed from the zirconium carbonate zirconium ammonium ((NH ₄ ) ₂ [Zr (CO ₃ ) ₂ (OH) ₂ ]) during the film formation (film formation) to form ZrO 2, The carboxyl groups are crosslinked to enable the formation of a film. The reaction at the time of this film formation (film formation) is such that a strong and strong film can be formed because a high crosslinking density (network structure) can be obtained by metal bridging of Zr while maintaining fluidity. Therefore, when zirconium carbonate is used, hardness and toughness can be exhibited in the coating that becomes the first black layer, and the scratch resistance and wear resistance of the coating that becomes the second black layer can be remarkably improved.

As a commercially available product of the aforementioned zirconium carbonate, "Baycoat 20" manufactured by Nippon Light Metal Co., Ltd. is suitably used.

The crosslinking agent (oxazoline group-containing polymer and / or zirconium ammonium carbonate) is used in an amount of not less than 2 parts by mass (more preferably not less than 3 parts by mass, and more preferably not less than 3 parts by mass, More preferably not less than 5 parts by mass), and preferably not more than 19 parts by mass (more preferably not more than 17 parts by mass, more preferably not more than 16 parts by mass). If the content of the cross-linking agent is less than the above range, the cross-linking reaction becomes insufficient and the formed film can not be densified, resulting in poor scratch resistance of the resulting black metal plate. On the other hand, if the content of the crosslinking agent is larger than the above range, the functional group (carboxyl group) of the first black layer decreases due to excessive crosslinking reaction, and the adhesion between the second black layer and the metal plate may be lowered.

The binder resin is preferably contained in an amount of 30 mass% or more (more preferably 55 mass% or more), preferably 85 mass% or less (more preferably 65 mass% or less) in 100 mass% of the total solid content of the aqueous black resin composition ). If the content of the binder resin is less than 30% by mass, the film formability of the film is lowered, the fixing of the surface-treated carbon black becomes insufficient, or coating unevenness occurs, which may cause appearance problems. On the other hand, when the content of the binder resin exceeds 85% by mass, the content of the surface-treated carbon black relatively decreases, and there is a possibility that sufficient blackness may not be obtained.

<Colloidal silica>

The water-based black resin composition preferably further contains colloidal silica. As a result, the surface-treated carbon black can be favorably fixed to the first black layer, and the corrosion resistance and hardness of the resulting black metal plate can be improved. The details of this mechanism are not clear, but it is presumed that silica is dissolved and eluted in a corrosive environment, resulting in a buffering action of pH or a passive film forming action. In addition, when the colloidal silica is contained, it is also effective to prevent cissing during application and drying of the aqueous black resin composition.

The colloidal silica is not particularly limited, but colloidal silica having a particle diameter of 4 to 20 nm is preferable from the viewpoints of the dispersibility and the corrosion resistance improving effect in the aqueous black resin composition. Specifically, colloidal silica having a particle diameter of 4 to 6 nm (Commercially available as "Snowtex (registered trademark) XS" manufactured by Nissan Chemical Industries, Ltd.) and colloidal silica having a particle diameter of 8 to 11 nm ("Snowtex (manufactured by Nissan Chemical Industries, Snowtex (registered trademark) S "manufactured by Nissan Chemical Industries, Ltd.) and colloidal silica having a particle diameter of 10 to 20 nm (a commercially available product" Snowtex (registered trademark) 40 " Trademark) XS &quot; is preferable.

The colloidal silica (solid content) is preferably 5 mass% or more (more preferably 10 mass% or more), and preferably 30 mass% or less (more preferably, 20% by mass or less). If the content of the colloidal silica is less than 5% by mass, the effect of improving the corrosion resistance and film hardness may not be recognized. On the other hand, when the content of the colloidal silica exceeds 30 mass%, the stability of the composition deteriorates and the viscosity of the composition increases with the elapse of time. Thus, further improvement effects such as corrosion resistance and the like are not obtained.

<Silane coupling agent>

The aqueous black resin composition may further contain a silane coupling agent. When the silane coupling agent is contained, adhesion between the first black layer and the metal sheet can be enhanced.

As the silane coupling agent, a silane coupling agent having a glycidoxy group at the terminal is preferable. For example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, . Vinyltris (beta -methoxyethoxy) silane is preferred.

The content of the silane coupling agent is preferably 5 parts by mass or more (more preferably 10 parts by mass or more) based on 100 parts by mass of the total solid content of the surface-treated carbon black, the binder resin and the colloidal silica And 25 parts by mass or less (more preferably 15 parts by mass or less). When the content of the silane coupling agent is less than 5 parts by mass, the effect obtained by adding the silane coupling agent may not be sufficiently obtained. On the other hand, when the content of the silane coupling agent exceeds 25 parts by mass, a large amount of unreacted silane coupling agent remains in the black metal sheet, and the corrosion resistance tends to be lowered.

&Lt; Other components >

The water-based black resin composition may further contain various additives as necessary insofar as the effect of the present invention is not impaired. For example, in the field of consumer electronics such as a thin television, complicated press processing or the like is often applied to a black metal plate, and workability is required as a required performance for a black metal plate. In such a case, by adding an aqueous wax to the aqueous black resin composition, lubricity can be imparted to the first black layer to improve workability. Examples of the water-based wax include polyethylenes such as "Chemipearl (registered trademark) W700", "Chemipear (registered trademark) W950" and "Chemipear (registered trademark) W900" manufactured by Mitsui Chemicals Inc. Wax.

The aqueous black resin composition can be prepared by mixing the above-mentioned respective components at a predetermined ratio. When the binder resin contains a crosslinking agent (an oxazoline group-containing polymer or zirconium ammonium carbonate), it is preferable to prepare a composition component other than the crosslinking agent and to add a crosslinking agent thereto .

The first black layer in the present invention can be formed by applying the above-described aqueous black resin composition to a predetermined dry film thickness on one side or both sides of the above-mentioned metal plate, followed by drying.

The film thickness (dry film thickness) of the first black layer is 0.4 탆 or more (preferably 0.5 탆 or more, and more preferably 0.6 탆 or more), 1.0 탆 or less (preferably 0.98 탆 or less, 0.9 μm or less). If the film thickness of the first black layer is less than 0.4 탆, the blackness of the first black layer, and thus the obtained black metal plate, becomes insufficient and a dark brown color appears. On the other hand, if the film thickness of the first black layer exceeds 1.0 탆, the blackness is excellent, but the effect of further improving the blackness is hardly obtained, while the time required for coating and drying becomes long, . If the film thickness of the first black layer is excessively large, the conductivity required when used in, for example, a field of consumer electronics such as a thin television can not be achieved.

The method of applying and drying the aqueous black resin composition when forming the first black layer is not particularly limited and a known method can be suitably employed. Examples of the application method of the composition include a bar coater method, a curtain flow coater method, a roll coater method, a spraying method, a spraying linger method and the like. Among them, from the viewpoint of cost, , The spraying method is preferable. The drying temperature is not particularly limited as long as the black layer is not deteriorated by heat. For example, the drying temperature is preferably about 50 to 160 캜, and more preferably about 70 to 140 캜.

In the preferred embodiment of the present invention, the blackness (L value) of the surface of the first black layer is 25 or less (more preferably 24 or less, more preferably 23 or less) , And the b value is 3 or less (more preferably 2.6 or less, further preferably 2.1 or less). On the other hand, in the present invention, the L value and the b value are brightness indices of measured values measured by the method specified in JIS Z8722, and can be measured by the methods described in the following examples. Regarding the L * value and the b * value converted based on the following formula, the preferable upper limit thereof is a range calculated from the upper limit value of the L value and the b value described above.

L * = 1.3632L-3.5904

b * = 1.5744b-0.0380

(Second black layer)

The second black layer laminated on the first black layer may be formed by applying a solvent-based black paint to a predetermined dry film thickness, followed by drying and baking. With such a second black layer, the film thickness of the first black layer formed by the water-based black resin composition is as thin as the above range, and coating defects due to coating unevenness, dust on the production line, The black metal plate can maintain a good appearance.

The solvent-based black paint is not particularly limited and those conventionally used for a black metal plate can be used. The solvent-based black paint is obtained by mixing, for example, a base resin (e.g., a high molecular weight polyester resin having a molecular weight of 10,000 to 20,000), a curing agent (e.g., melamine curing agent) Based anticorrosive pigments, magnesium phosphate-based anticorrosive pigments, calcium silicate-based anticorrosive pigments, etc.), extender pigments and the like, and further adding carbon black as a coloring pigment. Examples of commercially available products include "FLC495 Black", "FLC6000 Black", "FLC6070 Black", "FLC6080 Black", "FLC6090 Black", "FLC6100 Black", and "FLC6100 Black" manufactured by Nippon Fine Coatings Co., And &quot; HF1600 black &quot; manufactured by BASF Japan. The solvent-based black paint may be used alone, or two or more thereof may be used in combination. On the other hand, from the viewpoints of workability, scratch resistance and abrasion resistance, the Tg of the base resin (for example, polyester resin or the like) of the solvent-based black paint is preferably 15 to 30 캜.

The solvent-based black paint preferably contains resin particles. As a result, a black metal plate having a high blackness and a good uneven appearance and feeling can be obtained. For example, when resin particles are contained in the clear coat, a good uneven pattern can not be produced.

The resin particles may be organic particles (for example, acrylic beads, styrene acrylic beads, urethane beads, etc.), or inorganic particles (for example, glass beads, silica beads, etc.). In particular, acrylic beads are preferable because they are difficult to aggregate in a solvent-based black paint and are easily available. The resin particles may be used alone or in combination of two or more.

The particle diameter of the resin particles is preferably 14 占 퐉 or less, more preferably 12 占 퐉 or less, and even more preferably 10 占 퐉 or less, from the viewpoint of coatability when a paint is applied by a roll coater or the like. If the particle diameter of the resin particles exceeds 14 μm, there is a possibility that streaks [streaking] or the like may occur at the time of coating.

Particularly, the particle diameter of the resin particle is preferably not less than t (μm) and not more than 2t (μm), where t (μm) is the thickness of the second black layer. For example, when the coating layer of the second layer has a thickness of about 15 탆, vortex convection accompanying the volatilization occurs in the wet state when the solvent in the coating liquid volatilizes, and the resin particles move to the surface of the coating film, However, in the present invention, as described later, since the film thickness of the second black layer is thin, the occurrence of eddy convection can not be expected. If the film thickness of the second black layer and the particle diameter of the resin particle satisfy the above-described relationship, even if the film thickness of the second black layer is thin, good unevenness can be expressed.

The film thickness (dry film thickness) of the second black layer is desirably 1.4 μm or more (preferably 1.5 μm or more, more preferably 1.6 μm or more, further preferably 2 μm or more, particularly preferably 3 μm or more, (Preferably not more than 8 mu m, more preferably not more than 7 mu m, further preferably not more than 6.5 mu m, particularly preferably not more than 6 mu m). If the film thickness of the second black layer is less than 1.4 mu m, the appearance may be damaged or the blackness of the resulting black metal plate may become insufficient, and the film tends to be weakened against wear and scratches. On the other hand, if the film thickness of the second black layer exceeds 9 탆, the time required for coating and drying becomes longer, and the manufacturing cost tends to be increased or the bending workability tends to be impaired. On the other hand, when the solvent-based black paint contains resin particles, the film thickness (dry film thickness) of the second black layer is the thickness of the film formed of the solvent-based black paint excluding the resin particles, Is measured.

The method of coating, drying, and baking the solvent-based black paint in forming the second black layer is not particularly limited, and a known method can be suitably employed. As a coating method of the paint, there may be mentioned the method described in the first black layer formation, and among these, from the viewpoint of cost, the bar coater method, the roll coater method and the sprayer method are preferable. The drying and baking temperature is preferably about 200 to 240 占 폚, for example.

In the preferred embodiment of the present invention, the blackness (L value) of the black metal plate surface of the present invention (the surface of the second black layer laminated on the first black layer) Is 20 or less (more preferably 19 or less, further preferably 18 or less), and the b value is 1.5 or less (more preferably 1.2 or less, and further preferably 1.0 or less). On the other hand, in the present invention, the L value and the b value are brightness indices of measured values measured by the method specified in JIS Z8722, and can be measured by the methods described in the following examples. Regarding the L * value and the b * value converted based on the following formula, the preferable upper limit thereof is a range calculated from the upper limit value of the L value and the b value described above.

L * = 1.3632L-3.5904

b * = 1.5744b-0.0380

Example

Hereinafter, the present invention will be described in detail based on examples. It should be noted, however, that the present invention is not limited to the following examples, and all modifications that do not deviate from the spirit of the preceding and following matters are included in the technical scope of the present invention.

First, the evaluation method used in the embodiment will be described below.

(Black degree)

Using a spectrophotometer ("Spectrophotometer SQ2000" manufactured by Nippon Denshoku Industries Co., Ltd.), a blank (a metal plate on which only the first black layer was provided, or a first black layer and a second black layer , The L value and the b value of the thus-obtained L value, b value, or L value and b value were evaluated on the basis of the L * value and b * value converted on the basis of the following formula .

L * = 1.3632L-3.5904

b * = 1.5744b-0.0380

In the present invention, the L value of the first black layer is not more than 25, the L value of the first black layer and the second black layer (black metal plate) is not more than 20 (L * value is not more than 24) As well.

(Corrosion resistance (SST time))

A salt water test was conducted on a blank material (a metal plate provided with only the first black layer or a black metal plate having the first black layer and the second black layer) based on JIS Z2371 to obtain a white rust ) Was measured (SST time) until 5% was generated.

In the present invention, the SST time of the first black layer is at least 72 hours, and the SST time is at least 240 hours for the first black layer and the second black layer (black metal plate).

(Processability (T bending))

(Black metal plate) cut into a size of 50 mm x 50 mm was lightly bent with a vise with the surface (second black layer forming face) outward at room temperature (20 캜), and the same black metal plate And a crack was observed at the bending portion after the processing was visually observed or 10 times loupe. In the evaluation method, the number of black metal plates to be sandwiched is 0T, and the number of sheets to be formed is 1T, and the number of sheets to be 1T is larger than the number of sheets when cracks are generated, , 2T is the crack limit).

(My sand eraser abrasion)

A sand eraser of 6 mm in diameter was set on a sliding test apparatus and a sliding distance of about 26 mm was 200 reciprocating while a load of 16.5 N was applied to the surface (second black layer forming side) of the blank (black metal plate) (Base metal) was observed with naked eyes and evaluated according to the following criteria.

◎: no exposure of base metal is recognized at all

○: Exposure of base metal is extremely slight.

: The length of the exposed portion of the base metal is within 2 mm

X: length of the exposed portion of the base metal is more than 2 mm

(Scratch resistance (pencil hardness))

Based on JIS K5400 (1990), the pencil hardness at which the surface of the second black layer was not scratched by a pencil scratch tester was determined for a blank material (black metal plate).

(Water resistance (carbon black leakage test))

After immersing the sealing material (a metal plate having only the first black layer or a black metal plate having the first black layer and the second black layer) in a boiling water for 1 hour, the appearance change due to the outflow of carbon black from the coating film was visually observed And evaluated by the following criteria.

◎: No change in appearance

○: Very slight change

?: Decrease in blackness (gloss deterioration)

X: Appearance unevenness due to color dropout

(Appearance uneven)

The surface (second black layer forming side) of the sealing material (black metal plate) was evaluated based on the following criteria from visual observation and texture.

◎: Appearance of bright black and good irregularity and good texture

△ 1: Bright black is seen, but unevenness is not recognized

? 2: Bright black is seen, but the irregularities are too large and the texture is poor

[Example 1, Comparative Example 1 ']

(Fabrication of underfloor metal plate)

First, 26.3 parts by mass of an acidic colloidal silica ("SNOWTEX (registered trademark) O"; solid content 20% by mass, manufactured by Nissan Chemical Industries, Ltd.) and 95.3 parts by mass of aluminum oxide (Yoneyama Chemical Industry Co., Manufactured by Nippon Junyaku Co., Ltd.) and 19.5 parts by mass of a polyacrylic acid ("Julimer (registered trademark) AC-10-LP" manufactured by Nippon Junyaku Co., Ltd.); And 100 parts by mass of a solid content of 100% by mass) were further added, and further 1.13 parts by mass of a silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) To prepare a composition solution (solid content concentration: 1.7% by mass).

Next, the obtained undercoat treatment composition solution was applied to the front and back surfaces of an electrogalvanized steel sheet (EG; Zn adhesion amount 20 g / m ² ) or a hot-dip galvanized steel sheet (GI; Zn adhesion amount 45 g / m ² ) is applied such that the 10 ³ mg / m ² by dry weight, and thereafter, dried at 120 ℃ 60 seconds, to prepare a not-treated metal sheet. Hereinafter, an electroplated galvanized steel sheet is used as the untreated metal sheet EG and a hot-dip galvanized steel sheet is used as the untreated metal sheet GI.

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

An acrylic acid copolymer ("Primacor (registered trademark) 5990I" manufactured by The Dow Chemical Company) was added to an autoclave (content 1.0 L) having an emulsification facility equipped with a stirrer, a thermometer and a temperature controller, 200.0 parts by mass of an acrylic acid-derived constituent unit: 20% by mass and a melt index of 1300), a non-aqueous solution of polymaleic acid (Nonpol (registered trademark) PMA-50W manufactured by NOF Corporation, (Product of Harima Chemicals Inc.), 8.0 parts by mass of water, about 1100 (in terms of polystyrene), 50 mass% of product), 35.5 parts by mass of triethylamine, 6.9 parts by mass (1.5 equivalent parts) of 48% NaOH aqueous solution, Hartol FA3 &quot;) and 792.6 parts by mass of ion-exchanged water were added and sealed, followed by high-speed stirring at 150 DEG C and 5 atmospheric pressure for 3 hours, followed by cooling to 30 DEG C. [ Then, a silane coupling agent ("TSL8350" manufactured by Momentive Performance Materials Inc. (trade name: Toshiba Silicones Co., Ltd.), solid content 100 mass%) 10.4 mass , 31.2 parts by mass of polycarbodiimide ("SV-02" manufactured by Nisshinbo Inc.) and 72.8 parts by mass of ion-exchanged water were added and stirred for 10 minutes to obtain a resin emulsion having a solid content of 20% by mass, This was used as a binder resin precursor.

Subsequently, 423 parts by mass of pure water was added to 222 parts by mass of the surface-treated carbon black ("Superabrasoluble BA-8", solid content 13.5% by mass, manufactured by Kuretake Co., Ltd.) while stirring. Then, the resin emulsion , 50 parts by mass of colloidal silica (Snowtex (registered trademark) XS, solid content 20% by mass) was added, and a silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd., solid content: 100% by mass) , And 7.5 parts by mass of an oxazoline group-containing polymer (Nippon Shokubai Corporation "Epochros (registered trademark) K-2030E"; solid content 40% by mass) were added to prepare a water-based black resin composition.

The water-based black resin composition had a solid content concentration of 11.2% by mass and a content ratio of the surface-treated carbon black (solid content) was determined based on the total solid content of the composition (i.e., the total solid content of the surface-treated carbon black, the binder resin and the colloidal silica (The resin emulsion and the oxazoline group-containing polymer) (solid content) of the binder resin is 30% by mass in 100% by mass of the total solid content of the composition, 60% (Solid content) of the composition is 10% by weight of 100% by mass of the total solid content of the composition, and the content of the colloidal silica (solid content) is 100% And 12.5 parts by mass of the ring agent per 100 parts by mass of the total solids of the surface-treated carbon black, the binder resin and the colloidal silica.

&Lt; Coating of waterborne black resin composition >

The black resin composition obtained above was applied to the surface of the undercoating metal plate shown in Tables 1 to 4 by means of a bar coater so as to have a dry film thickness shown in Tables 1 to 4, And dried to form a first black metal layer.

(Formation of second black layer)

(Manufactured by Dainichi Seika Color & Chemicals Mfg Co., Ltd.) having a particle diameter of about 2 to 12 占 퐉 was added to a solvent-based black paint (FLC495 Black, manufactured by Nippon FinePacs Co., Rubcouleur) was added in an amount of 2 parts by mass based on 100 parts by mass of the dried solid content of the paint, and the viscosity was measured with a Ford cup. 4 and 50 seconds. Then, the surface of the first black layer was coated with a bar coating machine so as to have a dry film thickness shown in Tables 1 to 4, and then dried and baked at 230 DEG C for 60 seconds to obtain a 2 black layer was formed to obtain a thin film black-coated metal plate. The thin black-coated metal plate of each of Examples 1 to 4, wherein the thickness of the second black layer was 1.42 to 4.55 μm, and the thin black-coated metal plate of Comparative Example 1 ', in which the second black layer was not coated (thickness: 0 μm). On the other hand, the particle diameter of the acrylic beads to be added was 1.2 to 1.5 times the film thickness of the second black layer.

The L value, the L * value, the b value, and the b * value of the thin black coated metal sheet obtained by changing the film thicknesses of the first black layer and the second black layer as described above are shown in Tables 1 to 4, respectively. Tables 1 and 3 show the case where a ground metal plate EG is used as a metal plate, and Tables 2 and 4 show cases where a ground metal plate GI is used as a metal plate. Figs. 1 to 4 show the relationship between the film thickness of the second black layer and the L value or b value of the black metal plate in the thin film black-coated metal plate.

On the other hand, among the obtained thin film black-coated metal plates, the surface of the black-coated metal plate of Comparative Example 1 ', in which the thickness of the second black layer was 0 μm, was visually observed to find out coating defects such as uneven coating and dust. However, with respect to the black-coated metal plate of the example in which the second black layer was formed, appearance defects were not recognized by similar observation.

[Comparative Example 1]

(Black primer FP1817, manufactured by KCC Corporation (Korea)) was used in place of the aqueous black resin composition in the formation of the first black layer of Example 1, And then dried at 230 캜 for 60 seconds to form a first black metal layer and a second black layer in the same manner as in Example 1 to obtain a comparative thin film black coated metal plate.

The L value, L * value, b value, and b * value of the thin film black-coated metal plate for comparison obtained by changing the film thicknesses of the first black layer and the second black layer in the manner described above are shown in Tables 1 to 4 Respectively. Tables 1 and 3 show the case where a ground metal plate EG is used as a metal plate, and Tables 2 and 4 show cases where a ground metal plate GI is used as a metal plate. Figs. 1 to 4 show the relationship between the film thickness of the second black layer and the L value or b value of the black metal plate in the thin film black-coated metal plate.

[Example 2]

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

Except that the raw materials (surface-treated carbon black, binder resin (resin emulsion and oxazoline group-containing polymer), colloidal silica, silane coupling agent) as in Example 1 were used and the amounts used were changed as follows In the same manner as in Example 1, a water-based black resin composition was prepared.

That is, the amounts of the colloidal silica and the silane coupling agent used were fixed in the same manner as in Example 1 (colloidal silica (solid content): 10 mass% in 100 mass% of the total solid content, silane coupling agent: 100 mass parts in total solid content 12.5 parts by mass), the amount of the surface-treated carbon black to be used is such that the content of the solid content of the binder resin (the resin emulsion and the oxazoline group-containing polymer) is such that the solid content is the value shown in Table 5 in 100% by mass of the total solid content Emulsion and oxazoline group-containing polymer) in the total solids of 100% by mass was changed to the values shown in Table 5. On the other hand, the resin emulsion and the oxazoline group-containing polymer were fixed so that the mass ratio of each solid content was 95: 5 as the resin emulsion: oxazoline group-containing polymer.

&Lt; Coating of waterborne black resin composition >

The aqueous black resin composition obtained above was applied to the surface of the undercoated metal plate EG obtained in Example 1 by a bar coater so that the dry film thickness was about 0.7 μm and then dried at 160 ° C. for 60 seconds Thereby forming a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle diameter of about 6 占 퐉 were added to a solvent solid black paint ("FLC495 Black" manufactured by Nippon FinePacs Co., Ltd.) in an amount of 2 parts by mass based on 100 parts by mass of the dry solid content of the paint. 4, and the surface of the first black layer was coated on the surface of the first black layer by a bar coater so that the thickness of the dried black layer became about 4.0 μm. Thereafter, the coating was dried and baked at 230 ° C. for 60 seconds, Layer was formed to obtain a thin film black-coated metal plate. On the other hand, the particle diameter of the acrylic beads to be added was 1.5 times the film thickness of the second black layer.

The L value and the b value of the step of forming only the first black layer and the L value and the b value of the black metal plate having the second black layer formed on the first black layer were compared with each other, Table 5 shows the results.

[Example 3]

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

Except that the raw materials (surface-treated carbon black, binder resin (resin emulsion and oxazoline group-containing polymer), colloidal silica, silane coupling agent) as in Example 1 were used and the amounts used were changed as follows In the same manner as in Example 1, a water-based black resin composition was prepared. However, the oxazoline group-containing polymers were changed to those shown in some tables.

That is, the amount of the silane coupling agent used was fixed in the same manner as in Example 1 (silane coupling agent: 12.5 parts by mass based on 100 parts by mass of the total solid content), the amount of the colloidal silica used was such that the content of the solid content was 100% (The amount of the resin emulsion and the oxazoline group-containing polymer) so that the content of the surface-treated carbon black becomes 20% by mass in 100% by mass of the total solid content of the composition, The content of the solid content of the oxazoline group-containing polymer is set to a value shown in Table 6 (so that the content of the resin emulsion is &quot; 60 mass% - &quot; Content of oxazoline group-containing polymer &quot;).

&Lt; Coating of waterborne black resin composition >

The aqueous black resin composition obtained above was applied to the surface of the undercoated metal plate EG obtained in Example 1 by a bar coater so that the dry film thickness was about 0.7 μm and then dried at 160 ° C. for 60 seconds , Thereby forming a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle diameter of about 6 占 퐉 were added to a solvent solid black paint ("FLC495 Black" manufactured by Nippon FinePacs Co., Ltd.) in an amount of 2 parts by mass based on 100 parts by mass of the dry solid content of the paint. 4, and the surface of the first black layer was coated on the surface of the first black layer by a bar coater so that the thickness of the dried black layer became about 4.0 μm. Thereafter, the coating was dried and baked at 230 ° C. for 60 seconds, Layer was formed to obtain a thin film black-coated metal plate. On the other hand, the particle diameter of the acrylic beads to be added was 1.5 times the film thickness of the second black layer.

With respect to each of the obtained thin film black-coated metal sheets, the blackness (L value), corrosion resistance and workability of the black metal plate having the second black layer formed on the first black layer and the corrosion resistance and water resistance of the step of forming only the first black layer Table 6 shows the results.

[Example 4]

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

(Surface-treated carbon black, binder resin (resin (resin), and the like) as in Example 1, except that the oxazoline group-containing polymer was changed to ammonium zirconium carbonate ("Beecoat 20" Emulsion), colloidal silica, silane coupling agent) was used and the amounts used were changed as follows, to prepare a water-based black resin composition.

That is, the amount of the silane coupling agent used was fixed in the same manner as in Example 1 (silane coupling agent: 12.5 parts by mass based on 100 parts by mass of the total solid content), the amount of the colloidal silica used was such that the content of the solid content was 100% The amount of the surface-treated carbon black to be used is such that the content of the solid content is 20% by mass in 100% by mass of the total solid content of the composition so that the amount of the binder resin (resin emulsion and ammonium zirconium carbonate) So that the content of the solid content of zirconium ammonium carbonate is 60% by mass in the total solid content of 100% by mass of the solid content of the composition (the content of the resin emulsion is 60% by mass - Quot; content ratio &quot;).

&Lt; Coating of waterborne black resin composition >

The aqueous black resin composition obtained above was applied to the surface of the undercoated metal plate EG obtained in Example 1 by a bar coater so that the dry film thickness was about 0.7 μm and then dried at 160 ° C. for 60 seconds , Thereby forming a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle size of about 6 占 퐉 were added to 100 parts by mass of the dry solid content of the paint on a solvent-based black paint ("FLC6080 Black" manufactured by Nippon Fine Chemicals Co .; 4, and the surface of the first black layer was coated on the surface of the first black layer by a bar coater so that the thickness of the dried black layer became about 4.0 μm. Thereafter, the coating was dried and baked at 230 ° C. for 60 seconds, Layer was formed to obtain a thin film black-coated metal plate. On the other hand, the particle diameter of the acrylic beads to be added was 1.5 times the film thickness of the second black layer.

The obtained black thin film-coated metal sheet was evaluated for corrosion resistance and water resistance at the step of forming only the first black layer and blackness (L value), corrosion resistance, workability, Table 7 shows the sand eraser abrasion resistance and scratch resistance.

[Example 5, Comparative Example 5]

(Formation of first black layer)

The water-based black resin composition (content ratio of solid content of zirconium ammonium carbonate was 5% by mass) obtained in Example 4-4 was used to coat the surface of the undercoated metal plate EG obtained in Example 1 with a bar coater, And then dried at 160 캜 for 60 seconds to form a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle size of about 6 占 퐉 were added to 100 parts by mass of the dry solid content of the paint on a solvent-based black paint ("FLC6080 Black" manufactured by Nippon Fine Chemicals Co .; 4 for about 50 seconds and then applied to the surface of the first black layer by a bar coater so as to have a dry film thickness shown in Table 8 and then dried and baked at 230 캜 for 60 seconds, Layer was formed to obtain a thin film black-coated metal plate. On the other hand, the particle diameter of the acrylic beads to be added was 0.6 to 3 times the film thickness of the second black layer.

Table 8 shows the blackness (L value, corrosion resistance, workability, sand-eraser abrasion resistance and scratch resistance) of each of the obtained thin film black-coated metal plates (black metal plate having the second black layer formed on the first black layer).

[Example 6]

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

Except that the raw materials (surface-treated carbon black, binder resin (resin emulsion and oxazoline group-containing polymer), colloidal silica, silane coupling agent) as in Example 1 were used and the amounts used were changed as follows In the same manner as in Example 1, a water-based black resin composition was prepared.

That is, the amount of the silane coupling agent used was fixed in the same manner as in Example 1 (silane coupling agent: 12.5 parts by mass based on 100 parts by mass of the total solid content), and the amount of the surface- The amount of the binder resin (the resin emulsion and the oxazoline group-containing polymer) to be used is such that the content of the colloidal silica is such that the content of the solid content is as shown in Table 9 so that the amount of the colloidal silica becomes 20 mass% The total solid content of the oxazoline group-containing polymer) was changed to the value shown in Table 9. On the other hand, the resin emulsion and the oxazoline group-containing polymer were fixed so that the mass ratio of each solid content was 95: 5 as the resin emulsion: oxazoline group-containing polymer.

&Lt; Coating of waterborne black resin composition >

The aqueous black resin composition obtained above was applied to the surface of the undercoated metal plate EG obtained in Example 1 by a bar coater so that the dry film thickness was about 0.7 μm and then dried at 160 ° C. for 60 seconds , Thereby forming a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle diameter of about 6 占 퐉 were added to a solvent solid black paint ("FLC495 Black" manufactured by Nippon FinePacs Co., Ltd.) in an amount of 2 parts by mass based on 100 parts by mass of the dry solid content of the paint. 4, and the surface of the first black layer was coated on the surface of the first black layer by a bar coater so that the thickness of the dried black layer became about 4.0 μm. Thereafter, the coating was dried and baked at 230 ° C. for 60 seconds, Layer was formed to obtain a thin film black-coated metal plate. On the other hand, the particle diameter of the acrylic beads to be added was 1.5 times the film thickness of the second black layer.

For each thin film black-coated metal plate obtained, the corrosion resistance and water resistance of the step of forming only the first black layer and the blackness (L value), corrosion resistance, workability and the like of the black metal plate having the second black layer formed on the first black layer Table 9 shows the scratch resistance.

[Example 7]

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

Except that the raw materials (surface-treated carbon black, binder resin (resin emulsion and oxazoline group-containing polymer), colloidal silica, silane coupling agent) as in Example 1 were used and the amounts used were changed as follows In the same manner as in Example 1, a water-based black resin composition was prepared.

That is, the amount of the silane coupling agent used is such that the content thereof is as shown in Table 10 relative to 100 parts by mass of the total solid content, and the amount of the colloidal silica to be used is such that the content of the solid content is 20 mass% The amount of the surface-treated carbon black used is preferably such that the amount of the binder resin (resin emulsion and oxazoline group-containing polymer) is such that the content of the solid content is 20% by mass in 100% by mass of the total solid content of the composition, And 60% by mass of 100% by mass of the total solid content. On the other hand, the resin emulsion and the oxazoline group-containing polymer were fixed so that the mass ratio of each solid content was 95: 5 for the resin emulsion: oxazoline group-containing polymer.

&Lt; Coating of waterborne black resin composition >

The aqueous black resin composition obtained above was applied to the surface of the undercoated metal plate EG obtained in Example 1 by a bar coater so that the dry film thickness was about 0.7 μm and then dried at 160 ° C. for 60 seconds , Thereby forming a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle diameter of about 6 占 퐉 were added to a solvent solid black paint ("FLC495 Black" manufactured by Nippon FinePacs Co., Ltd.) in an amount of 2 parts by mass based on 100 parts by mass of the dry solid content of the paint. 4, and the surface of the first black layer was coated on the surface of the first black layer by a bar coater so that the thickness of the dried black layer became about 4.0 μm. Thereafter, the coating was dried and baked at 230 ° C. for 60 seconds, Layer was formed to obtain a thin film black-coated metal plate. On the other hand, the particle diameter of the acrylic beads to be added was 1.5 times the film thickness of the second black layer.

Corrosion resistance and water resistance of the obtained thin black coated metal sheet and the corrosion resistance and workability and scratch resistance of the black metal sheet having the second black layer formed on the first black layer were measured and shown in Table 10 Respectively.

[Example 8]

(Formation of first black layer)

&Lt; Preparation of aqueous black resin composition >

Except that the raw materials (surface-treated carbon black, binder resin (resin emulsion and oxazoline group-containing polymer), colloidal silica, silane coupling agent) as in Example 1 were used and the amounts used were changed as follows In the same manner as in Example 1, a water-based black resin composition was prepared.

That is, the amount of the silane coupling agent used was fixed in the same manner as in Example 1 (silane coupling agent: 12.5 parts by mass based on 100 parts by mass of the total solid content), and the amount of the surface- The amount of the binder resin (resin emulsion and oxazoline group-containing polymer) to be used is 20% by mass in 100% by mass, and the amount of the colloidal silica is 20% by mass in 100% by mass of the total solid content of the composition And the content of the solid content (the total solid content of the resin emulsion and the oxazoline group-containing polymer) was changed to 60% by mass in 100% by mass of the total solid content of the composition. On the other hand, the resin emulsion and the oxazoline group-containing polymer were fixed so that the mass ratio of each solid content was 95: 5 as the resin emulsion: oxazoline group-containing polymer.

&Lt; Coating of waterborne black resin composition >

The aqueous black resin composition obtained above was applied to the surface of the undercoated metal plate EG obtained in Example 1 by a bar coater so that the dry film thickness was about 0.7 μm and then dried at 160 ° C. for 60 seconds , Thereby forming a first black metal layer.

(Formation of second black layer)

2 parts by mass of acrylic beads having a particle diameter (in the range of about 2 to 14 m) shown in Table 11 were added to a solvent solid black paint ("FLC495 black" manufactured by Nippon Fine Chemicals Co., Ltd.) based on 100 parts by mass of dry solid content of the paint, And the viscosity was measured using a Ford Cup No. 4, and then the coating was applied to the surface of the first black layer so as to have a dry film thickness (in a range of about 2.0 to 7.0 μm) shown in Table 11 with a bar coater, Dried and baked for a second time to form a second black layer to obtain a thin film black coated metal plate.

Table 11 shows the evaluation of the appearance of concavo-convex appearance of each of the obtained thin-film black paint-coated metal sheets.

Claims (8)

As a thin film black-coated metal plate,
A first black layer formed of a water-based black resin composition and having a thickness of 0.4 to 1.0 m is laminated on at least one surface of a metal sheet, and on the first black layer, 2 black layers are laminated,
The water-based black resin composition contains a surface-treated carbon black having a surface coated with an aqueous resin,
(Μm) or more and 2t (μm) or less when the solvent-based black paint contains resin particles and the particle diameter of the resin particles is 14 μm or less and the film thickness of the second black layer is t
Thin - film black painted metal plate. The method according to claim 1,
Wherein the content of the surface-treated carbon black (solid content) is 10 to 40 mass% in 100 mass% of the total solid content of the water-based black resin composition. The method according to claim 1,
Wherein the blackness (L value) of the surface of the first black layer is 25 or less and the b value is 3 or less. delete The method according to claim 1,
Wherein the solvent-based black paint contains resin particles having a particle diameter of 14 占 퐉 or less and the blackness (L value) of the surface of the second black layer laminated on the first black layer is 20 or less and the b value is 1.5 or less Painted metal plate. The method according to any one of claims 1 to 3 and 5,
Wherein the aqueous black resin composition contains a binder resin and the binder resin is selected from an olefin-?,? -Unsaturated carboxylic acid copolymer, an?,? - unsaturated carboxylic acid polymer, an oxazoline group containing polymer and zirconium ammonium carbonate Wherein the content of the crosslinking agent is 2 to 19 parts by mass based on 100 parts by mass of the total of the olefin-?,? -Unsaturated carboxylic acid copolymer and?,? - unsaturated carboxylic acid polymer, A thin film black coated metal sheet having 30 to 85 mass% of 100 mass% of the total solid content of the resin composition. The method according to claim 6,
Wherein the water-based black resin composition further contains colloidal silica, and the content of the colloidal silica is 5 to 30 mass% of 100 mass% of the total solid content in the aqueous black resin composition. 8. The method of claim 7,
Wherein the water-based black resin composition contains 5 to 25 parts by mass of a silane coupling agent based on 100 parts by mass of the total solid content of the surface-treated carbon black, the binder resin and the colloidal silica.

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