JP2003320614A - Pre-coated metal sheet excellent in processability, coating film adhesion and photocatalytic activity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pre-coated metal sheet excellent in coating film adhesion, processability and photocatalytic activity, by forming a barrier layer 3 and a photocatalyst layer 4 by coating adjusted in moisture content. <P>SOLUTION: The pre-coated metal sheet 1 is constituted by successively laminating a colored organic coating film 2, the barrier layer 3 having a three- dimensional reticulated structure of acrylic silicate formed from a coating composition with a moisture content of 0.1-10 mass%, and the photocatalyst layer 4 formed from a coating composition with a moisture content of 0.05-8 mass% on the surface of a substrate metal sheet 1. The barrier layer 3 is formed from coating having a composition comprising 20-70% of a base resin being a partial hydrolysate condensate of organoalkoxysilane, 20-70% of a polymer or copolymer of an unsaturated ethylenic monomer, and 10-60% of colloidal silica. The photocatalyst layer 4 is formed using coating prepared by compounding 10-60 pts.mass of photocatalyst particles with a mean particle size of 200 nm with 100 pts.mass of the same base resin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precoated metal sheet which has post processability and is excellent in coating film adhesion and photocatalytic activity.

[0002]

_2. Description of the Related Art A coating film formed from a paint containing a photocatalyst such as TiO ₂ has stain degrading property, antibacterial property, deodorizing property, NO _x · SO _x resolution, etc. It exhibits no functionality. These functions are caused by photocatalytic activity, and a photocatalytic function is imparted by forming an inorganic coating film composed of anatase-type TiO ₂ particles and silica on the surface of the base material (JP-A-7-113272, JP 8-
164334, WO 96/29375). Although the photocatalytic activity is effective in decomposing and removing organic stains, offensive odors, NO _x and SO _x , the organic components of the coating film are decomposed by active oxygen generated by irradiation with ultraviolet light and cause film peeling in the organic base. The choking phenomenon occurs. In order to suppress the choking phenomenon, an organic coating film in which anatase-type TiO ₂ particles are dispersed based on a relatively stable fluororesin is also known (Japanese Patent Laid-Open No. 7-171408), but an inorganic base is usually used.

The organic coating film has a drawback in that it causes a choking phenomenon, but has better workability in bending, drawing and the like as compared with the inorganic coating film. Utilizing good workability,
In order to improve the stability of an organic coating film, an organic-inorganic composite coating film (JP-A-10-225658) in which anatase-type TiO ₂ particles are dispersed in a silica-organoalkoxysilane-based coating material, an underlying organic coating film and a photocatalyst A silicone-based undercoat layer for protecting the organic coating film from active oxygen is provided between the layers (Japanese Patent Laid-Open No. 11-50006), and a barrier layer and a photocatalyst layer provided with processability are provided on the organic coating film. Laminating (Japanese Patent Laid-Open No. 2001-131768) is also known.

[0004]

The inorganic coating film in which photocatalyst particles are dispersed has excellent weather resistance, but it is peeled off from the base material / metal plate starting from a crack generated during bending or drawing. Cheap. Therefore, in applications such as building materials and home appliances that are commercialized by bending and drawing, it is unavoidable to impart photocatalytic activity by the post-coating method of painting after processing. Considering the drawbacks of post-coating, which has low productivity and increases the product cost, pre-coating which is advantageous for reducing the manufacturing cost is required. However, no inorganic pre-coated steel sheet with excellent photocatalytic activity that satisfies the workability required for applications such as building materials and home appliances has been developed.

The organic / inorganic composite coating film has better workability than the inorganic coating film, but it must be thinned in order to satisfy the workability required for the precoated metal sheet. When the coating film is thin, the hiding power is low even when a pigment is added, and the color tone of the substrate is transparent, so that the degree of freedom in adjusting the color is reduced. A desired color is imparted to the coated metal plate by the coating composition in which the photocatalyst layer formed of the organic / inorganic composite coating is formed on the organic coating formed on the base. However, since the underlying organic coating film is in direct contact with the photocatalyst layer, the chalking phenomenon is likely to occur. Although the choking phenomenon can be suppressed by a coating structure in which an undercoat layer is interposed between the underlying organic coating film and the photocatalyst layer, the coating structure is not only complicated but the undercoat layer and the photocatalyst layer have good adhesion. A low organic-inorganic composite coating film, and cracks and peeling of the coating film tend to occur during post-processing.

[0006]

The present invention has been devised to solve such a problem, and by forming a barrier layer and a photocatalyst layer from a paint having a controlled water content,
It is an object of the present invention to provide a precoated metal plate having excellent processability, coating adhesion and photocatalytic activity. The precoated metal sheet of the present invention has a water content of 0.1 to 1 in order to achieve the object.
Based on a barrier layer having a three-dimensional network structure of acrylic silicate formed from a coating composition of 0 mass% and a photocatalyst layer formed from a coating composition having a water content of 0.05 to 8 mass% containing photocatalyst particles. It is characterized in that it is sequentially laminated on the surface of the material / metal plate through a colored organic coating film.

The barrier layer is preferably a partial hydrolysis-condensation product of an organoalkoxysilane containing alkoxysilane: 20 to 70% by mass, a polymer or copolymer of an unsaturated ethylenic monomer: 20 to 70% by mass, Colloidal silica: having a composition of 10 to 60 mass%. In the photocatalyst layer, photocatalyst particles having an average particle diameter of 200 nm or less are dispersed in a coating film having the same composition as that of the barrier layer at a ratio of 10 to 60 parts by mass with respect to 100 parts by mass of the base resin.

The coating material for the barrier layer contains colloidal silica, a partially hydrolyzed condensate of organoalkoxysilane, a polymer or copolymer of an unsaturated ethylenic monomer, and has a water content of 0.1 to 10% by mass. It is prepared by adjusting to. The photocatalyst layer coating is prepared by dispersing photocatalyst particles having an average particle diameter of 200 nm or less in the same coating composition as the barrier layer coating,
It is prepared by adjusting the water content to 0.05 to 8% by mass. The precoated metal plate of the present invention is produced by forming a colored organic coating film on a substrate / metal plate, and then sequentially coating and baking a coating material for a barrier layer and a coating material for a photocatalyst layer.

[0009]

[Function] In a coating film prepared from a coating material in which photocatalyst particles are dispersed in a base resin mixed with an inorganic silica resin or acrylic resin, active oxygen generated by the photocatalytic reaction of the photocatalyst particles excited by ultraviolet light irradiation is acrylic. The choking phenomenon that decomposes the resin is unavoidable. When the choking phenomenon occurs, the coating film easily peels off from the base material / metal plate, and the weather resistance of the coated metal plate deteriorates. On the other hand, in the case of a coating film prepared from a coating material in which colloidal silica and photocatalyst particles are mixed with acrylic silicate produced by the polymerization reaction of acrylic and organoalkoxysilane, excellent weather resistance is exhibited despite the similar photocatalytic reaction. Show. The excellent weather resistance of the acrylic silicate coating film is presumed as follows.

Acrylic silicate forms a three-dimensional network structure in which colloidal silica and photocatalyst particles are involved. The three-dimensional network structure of acrylic silicate is maintained on the silicate side even if a part of acrylic is cut and cut by active oxygen. As a result, the chalking phenomenon does not occur, and the weather resistance of the coating film improves. Also. By introducing an acrylic component, flexibility is imparted to the coating film, and since the photocatalyst particles can be dispersed in the coating film at a relatively high concentration, the coating film has excellent processability and photocatalytic activity. When the photocatalyst layer is laminated after coating and baking the acrylic silicate-based paint containing colloidal silica on the colored organic coating film, the coating film between the colored organic coating film and the photocatalyst layer serves as a barrier layer. Protects the coating from photocatalytic reactions. However, when the paint is baked in a short time as in the normal pre-coated steel sheet manufacturing process, the colored organic coating film / barrier layer or barrier layer / photocatalyst layer interface does not adhere well even if the baking conditions such as temperature and time are changed. Therefore, it was difficult to achieve both adhesions.

As a result of various investigations and studies on the adhesion of a coating having a three-layer structure of a colored organic coating / barrier layer / photocatalyst layer, the water content of the coating for the barrier layer and the coating for the photocatalyst layer was found to affect the coating adhesion. I found that it had a great influence. In order to improve the adhesiveness between the colored organic coating film / barrier layer, a coating material for a barrier layer having a small amount of water and a large amount of organic substances involved in binding is preferable. On the other hand, in order to improve the adhesion between the barrier layer and the photocatalyst layer, the barrier layer and the photocatalyst layer are bonded to each other by hydrolysis and polycondensation, and therefore a coating material for a barrier layer having a large water content is preferable. Considering the adhesion of the barrier layer to the colored organic coating film and the photocatalyst layer, it can be seen that the water content of the coating material for the barrier layer has an appropriate range. From the research results by the present inventors, it was clarified that when the water content of the barrier layer is adjusted to 0.1 to 10% by mass, the adhesiveness of the colored organic coating film / barrier layer and the barrier layer / photocatalyst layer are compatible with each other. Was done.

The water content of the photocatalyst layer coating material must also be adjusted according to the water content of the barrier layer coating material. That is, unless the amount of hydroxyl groups corresponding to the hydroxyl groups present on the surface of the barrier layer is obtained on the photocatalyst layer side, the bond at the barrier layer / photocatalyst layer interface tends to be non-uniform. When adjusting the water content of the photocatalyst layer coating material to 0.05 to 8 mass% in accordance with the barrier layer coating material having a water content of 0.1 to 10% by mass, the number of hydroxyl groups in the barrier layer side and the photocatalyst layer side is The dehydration polycondensation uniformly progresses in conformity with each other. As a result, the adhesion between the barrier layer / photocatalyst layer is improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a precoated metal plate according to the present invention, a colored organic coating film 2, a barrier layer 3 and a photocatalyst layer 4 are sequentially laminated on a substrate / metal plate 1 (FIG. 1). As the base material / metal plate 1, a cold rolled steel plate, a plated steel plate, a stainless steel plate, an aluminum plate, an aluminum alloy plate, a copper plate, a copper alloy plate or the like can be used. The galvanized steel sheet includes hot-dip galvanized steel sheet and hot-dip Z
There are n-Al alloy plated steel sheet, hot-dip Zn-Al-Mg alloy-plated steel sheet, hot-dip Al-plated steel sheet, hot-dip Al-Si alloy-plated steel sheet, electric Zn-plated steel sheet, electric zinc-alloy plated steel sheet and the like. The base material / metal plate 1 is, if necessary, reactive chromate treatment, coating chromate treatment, phosphate treatment,
After appropriate pretreatment such as chromium-free chemical conversion treatment, the coating for colored organic coating, the coating for barrier layer, and the coating for photocatalyst layer are sequentially applied and baked. Appropriate methods such as a roll coating method, a curtain coating method, a spraying method, a bar coating method and a dipping method can be adopted for applying the paint.

The colored organic coating film 2 preferably has a two-layer structure of an undercoat coating film 2u containing an anticorrosive pigment and an overcoat coating film 2t containing a color pigment in order to improve corrosion resistance. The base coating film 2u is made of polyester, epoxy, acrylic, fluorine or a mixed resin thereof, and is a paint containing strontium chromate, zinc chromate, modified silica or the like as a rust preventive pigment, and is 3 to 15 μm.
It is formed with a film thickness of m (preferably 6 to 9 μm). In order to secure the adhesion to the undercoat film 2u and the barrier layer 3, the paint for the overcoat film 2t has a polar group-containing polyester, epoxy, polyurethane, acrylic,
One type or two or more types such as fluorine type are used for the base resin. By blending the base resin with a coloring pigment such as titanium oxide, carbon black, titanium yellow, red iron oxide, etc., the top coat film 2t having a high hiding property is formed. The paint for forming the topcoat 2t is preferably a paint containing no wax such as polyethylene or fluorine in order to improve the adhesion to the barrier layer 3. 2 tons of top coating film is 10 to 25
It is formed with a film thickness of μm (preferably 15 to 18 μm).

The barrier layer 3 is preferably 0.1 to 1 so that the organic components of the colored organic coating film 2 are not deteriorated by a photocatalytic reaction.
It is formed with a film thickness of 5 μm. When the film thickness is less than 0.1 μm, the unevenness of the underlayer cannot be sufficiently covered, and the coating film peeling starting from the film breakage caused by the convex portion of the underlayer tends to occur. On the other hand, with a thick film having a thickness of more than 5 μm, cracks and peeling are likely to occur during bending, drawing and the like. The coating material for the barrier layer is a partially hydrolyzed condensate of organoalkoxysilane containing alkoxysilane: 20 to 80% by mass, polymer or copolymer of unsaturated ethylenic monomer: 20 to 70% by mass, colloidal silica: A paint prepared to have a composition of 10 to 60% by mass is preferable, and the water content is adjusted to 0.1 to 10% by mass.

The partially hydrolyzed condensate of organoalkoxysilane is an organohydroxysilane represented by the formula R ¹ Si (OH) ₃ or a partial condensate thereof, and is a mixed dispersion of acidic aqueous colloidal silica and non-aqueous colloidal silica. It is obtained by hydrolyzing an organoalkoxysilane of the formula R ¹ Si (OR ² ) _{3 in} a liquid. In the formula, R ¹ is an alkyl group having 1 to 3 carbon atoms, vinyl group, 3,4-epoxycyclohexylethyl group, γ-glycidoxypropyl group, γ-
Represents a methacryloxypropyl group, γ-mercaptopropyl group or γ-chloropropyl group, and R ² has 1 to 3 carbon atoms
Is an alkyl group or an aryl group. The partial hydrolysis-condensation product of the organoalkoxysilane is preferably added in an amount of 20% by mass or more in order to improve the adhesion and weather resistance of the barrier layer. However, if it exceeds 80% by mass, the impact resistance of the coating film decreases.

The unsaturated ethylenic monomers include methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, n-butyl methacrylate, isobutyl methacrylate, t. -Acrylic acid esters such as butyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-ethylhexyl methacrylate, methoxydiethylene glycol methacrylate, methoxytetraethylene glycol methacrylate, allyl methacrylate Methacrylic acid ester, etc. It is also possible to blend the lens monomer. When the polymer or copolymer of unsaturated ethylenic monomer is blended in a proportion of 20% by mass or more, the barrier layer 3 can be formed into a film having a thickness of several μm or more, and cracks caused by heat shrinkage or the like can be prevented and processed. The property is also improved. However, if the content exceeds 70% by mass, the choking phenomenon due to active oxygen is likely to occur and the coating film life is shortened.

Colloidal silica is blended in an amount of 10% by mass or more in order to impart required hardness to the barrier layer 3. But,
When an excessive amount of colloidal silica exceeding 60% by mass is blended, the impact resistance of the barrier layer 3 is lowered. The water content of the barrier layer paint prepared to have a predetermined composition is adjusted within the range of 0.1 to 10% by mass. Interlayer adhesion of the barrier layer 3 / photocatalyst layer 4 is secured with a water content of 0.1% by mass or more.
If the amount of water exceeds 0% by mass, the interlayer adhesion of the colored organic coating film 2 / barrier layer 3 will decrease.

To form the photocatalyst layer 4, a base resin having the same composition as the coating material for the barrier layer is used in order to secure the affinity for the barrier layer 3. A photocatalyst layer coating material is prepared by blending the photocatalyst particles 5 with the base resin. The coating material for the photocatalyst layer is adjusted to have a water content of 0.05% by mass or more in order to improve the interlayer adhesion between the barrier layer 3 and the photocatalyst layer 4. However, when the water content exceeds 8% by mass, hydrolysis easily occurs and polycondensation of the photocatalyst layer 4 is accelerated.
Defects such as cracks and peeling are likely to occur in the photocatalyst layer 4 during bending and drawing. The photocatalyst particles 5 contain Ti
O _2, ZnO, there are WO _3, FeTiO _3, SrTiO _3, etc., following the average particle diameter 200nm to ensure the surface area necessary for the photocatalytic reaction is preferred. Of these, anatase-type titanium oxide is preferable because it exhibits excellent photocatalytic activity and is easily available. When the photocatalyst particles 5 are dispersed in a proportion of 10% by mass or more, the photocatalyst layer 4 exhibiting sufficient photocatalytic activity is formed. However, when the content is more than 60% by mass, the resin content is insufficient and the dense photocatalyst layer 4 cannot be formed. Therefore, cracks are generated during bending or drawing.
Peeling or the like is likely to occur on the photocatalyst layer 4.

[0020]

EXAMPLES [Preparation of Solution A] After mixing an acidic aqueous colloidal silica dispersion and a methanolic colloidal silica dispersion, methylmethoxysilane was added and the mixture was stirred at room temperature for 5.5.
The hydrolysis was completed by stirring for a time. Isopropyl alcohol was added to the hydrolysis product to obtain a solid content of 2
A 0 mass% solution A was prepared. [Preparation of Solution B] Acrylic acid ester (a mixture of methyl methacrylate: n-butyl methacrylate = 2: 1) was diluted with a mixed solution of isopropanol: ethylene glycol monobutyl ether = 2: 5, and azobisisobutylnitrile was added under a nitrogen atmosphere. (AIBN) was added and polymerized at 80 ° C. for 6 hours to prepare a solution B.

[Preparation of Coating C for Barrier Layer] Solution A and solution B were mixed, and the partial hydrolysis-condensation product of methyltriethoxysilane was 32% by mass in terms of solid content composition ratio of unsaturated ethylenic monomer. Polymer: 27% by mass, colloidal silica: 3
A coating material C for barrier layer of 9% by mass was prepared. [Preparation of Coating D for Photocatalyst Layer] Anatase type titanium oxide having an average particle size of 7 nm is used as the coating C for the barrier layer as the photocatalyst particles 5.
To prepare a photocatalyst layer coating material D in which the ratio of the photocatalyst particles 5 to the entire photocatalyst layer 4 was 60% by mass.

Using the prepared coating C for barrier layer and coating D for photocatalyst layer, a precoated metal plate was manufactured in the following steps. [Film Forming Example 1: Inventive Example] Zn adhesion amount per side 45 g / m
^2. Hot-dip Zn-plated steel sheet with a plate thickness of 0.6 mm was coated with chromate and then coated with an undercoat paint at 200 ° C x 40
An undercoat coating film 2u having a film thickness of 5 μm was formed by heating and drying for 2 seconds. As the undercoat paint, a paint was used in which 5% by mass of a strontium chromate rust preventive pigment was mixed with an epoxy base resin. Polyvinylidene fluoride (PVDF) / acrylic resin = 7/3 topcoat paint is applied on top of the undercoat 2u, and dried and baked at 250 ° C for 60 seconds to give a film thickness of 1
An 8 μm topcoat coating film 2 t (colored organic coating film 2) was formed. Apply the barrier layer coating material C to the top coating film 2t 21
After forming the barrier layer 3 having a film thickness of 1.2 μm by drying and baking at 5 ° C. for 40 seconds, the photocatalyst layer coating material D is applied to form the barrier layer 23.
The photocatalyst layer 4 having a film thickness of 2 μm was formed by drying and baking at 0 ° C. for 1 minute. At this time, the water content of the barrier layer coating material C and the photocatalyst layer coating material D was adjusted so that the water content of the barrier layer 3 and the photocatalyst layer 4 was within the range of 0.3 to 5 mass%.

[Film Forming Example 2: Comparative Example] Film forming example 1 except that a barrier layer coating material C having a water content of 0.05 mass% and a photocatalyst layer coating material D having a water content of 0.03 mass% were used. Under the same conditions, a colored organic coating film 2, a barrier layer 3 and a photocatalyst layer 4 were formed. [Film Forming Example 3: Comparative Example] Colored organic coating under the same conditions as Film Forming Example 1 except that a barrier layer coating material C having a water content of 15% by mass and a photocatalyst layer coating material D having a water content of 10% by mass were used. A film 2, a barrier layer 3 and a photocatalyst layer 4 were formed.

Test pieces were cut out from each of the obtained coated steel sheets and subjected to the following tests. [Initial coating film adhesion test] Immediately after film formation, water-cooled and sufficiently dried coating film was attached with an adhesive tape and immediately peeled off, and then the coating film surface was observed. The initial coating film adhesion was evaluated by setting the coating film in which peeling did not occur as ◯ and the coating film in which peeling was detected as x. [Film adhesion test after immersion in boiling water] The test piece was immersed in boiling water at 100 ° C for 2 hours and dried sufficiently, and then the adhesion of the coating film was evaluated by the same adhesive tape sticking / peeling test.

[Film coating adhesion test] Two to five plates of the same thickness are sandwiched on the side opposite to the top coat film 2t of the test piece left in a thermostatic chamber at a temperature of 20 ° C., and a 180 ° bending test is conducted. did.
An adhesive tape was attached to the coating film on the outside of the bent portion and immediately peeled off, and then the peeled state of the coating film was investigated. The processing adhesion of the coating film was evaluated by setting the coating film which did not peel off below 2T bending to ◯, the coating film which did not peel off below 5T bending to Δ and the coating film which peeled off below 5T bending to x. [Photocatalytic activity test] A test piece was attached to the ceiling surface of a test chamber with a width of 300 mm, a height of 500 mm, and a depth of 300 mm.
A cigarette tar was attached to the photocatalyst layer 4 on the surface of the test piece.
After the tar was adhered until the Δb value on the surface of the test piece was 1 or more, the fluorescent lamp arranged at a position 10 cm away from the test piece was turned on and the test piece was irradiated. After the irradiation was continued for 24 hours, the b value of the test piece was measured. Tar before adhesion values b _1, Jani values b ₂ and the value b ₃ the tar decomposition rate after the test piece irradiation after deposition _{(%) = (b 2 -b} 3) / (b 2 -b 1) × 100 Substituting into the equation, the tar decomposition rate was calculated.

As seen from the test results in Table 1, by adjusting the water content of the barrier layer 3 and the photocatalyst layer 4, the initial coating film adhesion and the coating film adhesion after immersion in boiling water were improved. . In addition, the colored organic coating film 2 / barrier layer 3 and barrier layer 3
/ Since the interlayer adhesion of the photocatalyst layer 4 was good, it had the workability required for the precoated metal plate to be post-processed, and the photocatalytic activity was also excellent. On the other hand, in Comparative Examples in which the water content of the barrier layer 3 and the photocatalyst layer 4 is inappropriate, the initial coating film adhesion and the coating film adhesion after immersion in boiling water are poor, and the workability required for the precoated metal plate is insufficient, It was also inferior in photocatalytic activity.

[0027]

[0028]

As described above, in the precoated metal sheet of the present invention, the barrier layer and the photocatalyst layer are formed by the coating material whose water content is adjusted. Therefore, the colored organic coating film / barrier layer and barrier layer / The photocatalyst layer has good interlayer adhesion, and has the workability necessary for precoating in which defects such as cracks and peeling do not occur in the coating film even after post-processing. Moreover, since it is provided with photocatalytic activity, it is used in a wide range of fields such as exterior building materials, external home appliances housings, and ceiling materials.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a coating film configuration of a precoated metal plate according to the present invention.

[Explanation of symbols]

1: Base material / metal plate 2: Colored organic coating film 2u: Undercoat coating film 2t: Topcoat coating film 3: Barrier layer 4: Photocatalyst layer 5: Photocatalyst particles

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) C23C 28/00 C23C 28/00 Z (72) Inventor Hiroshige Nakamura 7-1 Takaya Shinmachi, Ichikawa City, Chiba Nisshin Steel Technical Research Institute F-term (reference) 4D075 AE03 CA13 CA32 CA33 CA34 CA44 DA06 DB02 DB04 DB05 DB06 DB07 DC01 DC10 DC18 EA06 EA10 EB17 EB22 EB33 EB43 EB47 EB56 EC02 EC03 EC53 EC54 4F100 AA20B AA21 AA22 AB52BAK19A25 AB01B25AK53A18 AB01B25AK53A18 AB01B25AK53A18 AB01B25A23B01A25 BA04 BA07 BA10B BA10D CA15 CA30B CB00A CB00B DE01B EH71 EJ69 HB00C JA20B JB12A JD01A JL10C YY00A YY00B 4G069 AA03 BA02A BA02B BA04A BA04B A15 BA15 BA15 BA17B A17 BA22B A17 AB4 EC17A22

Claims (3)

[Claims] 1. A barrier layer having a three-dimensional network structure of acrylic silicate formed from a coating composition having a water content of 0.1 to 10% by mass, and a water content of 0.05 containing photocatalyst particles.
Processability, coating adhesion, photocatalytic activity, characterized in that a photocatalyst layer formed from a coating composition of 8 to 8% by mass is sequentially laminated on the surface of a substrate / metal plate through a colored organic coating film. Excellent pre-coated metal plate. 2. A partially hydrolyzed condensate of an organoalkoxysilane in which the barrier layer contains an alkoxysilane: 20 to 7
0% by mass, polymer or copolymer of unsaturated ethylenic monomer: 20 to 70% by mass, colloidal silica: 10 to 60
The precoated metal sheet according to claim 1, having a composition of mass%. 3. A partially hydrolyzed condensate of organoalkoxysilane whose photocatalyst layer contains alkoxysilane: 20 to 7
0% by mass, polymer or copolymer of unsaturated ethylenic monomer: 20 to 70% by mass, colloidal silica: 10 to 60
The precoated metal sheet according to claim 1, wherein the photocatalyst particles having an average particle diameter of 200 nm or less are dispersed in a ratio of 10 to 60 parts by mass with respect to 100 parts by mass of the base resin.