JP2020171874A - Covering material and inactivation method of germ or virus - Google Patents

Abstract

To provide a covering material that can increase an amount of light reaching a photocatalyst and can efficiently develop photocatalysis.SOLUTION: In a first embodiment, a covering material 1 is provided that includes: a base material 2 the surface of which is at least partially formed of a covering layer 21 having reflectance of light of a wavelength of 555 nm of 85% or more; and a photocatalyst layer 3 located on the covering layer 21. In a second embodiment, a covering material 1 is provided that is identical to the covering material 1 in the first embodiment except that a photocatalyst layer 3 includes anatase type or rutile type titanium oxide photocatalyst 30. In a third embodiment, a covering material 1 is provided that is identical to the covering material 1 in the first and second embodiment except that a base material 2 includes an intermediate protective layer 4 provided between the covering layer 1 and the photocatalyst layer 3. In a fourth embodiment, a covering material 1 is provided that is identical to the covering material 1 in the first, second and third embodiment except that the base material 2 includes a plated steel sheet 22 and a covering layer 21 provided on the plated steel sheet 22. An inactivation method of germ or virus is provided that activates the photocatalyst 30 by irradiating the photocatalyst layer 3 of the covering material 1 with light to thereby inactivate germ or virus.SELECTED DRAWING: Figure 1

Description

The present disclosure generally relates to a coating material and a method for inactivating bacteria or viruses, and more particularly to a coating material provided with a photocatalytic layer and a method for inactivating bacteria or viruses using the coating material.

The photocatalyst has a photocatalytic action such as a hydrophilic action, an antifouling action, and an inactivating action of a bacterium or a virus. Among these photocatalytic actions, the inactivating action of bacteria or viruses has attracted attention. Further, a photocatalytic action is imparted to the base material by providing a coating film containing a photocatalyst on the colored base material. For example, the photocatalytic colored coating article of Patent Document 1 includes a base material, a colored coating film, and a photocatalytic coating film.

Japanese Unexamined Patent Publication No. 2001-149855

Since the photocatalytic action is exhibited by the photoexcitation action generated by irradiating the photocatalyst with light, the photocatalytic action can be efficiently expressed by increasing the amount of light reaching the photocatalyst. Therefore, by increasing the amount of light that reaches the photocatalyst, it is easy to develop the inactivating action of the fungus or virus by the photocatalyst.

An object of the present disclosure is to provide a coating material capable of increasing the amount of light reaching the photocatalyst and efficiently exhibiting a photocatalytic action, and a method for inactivating bacteria or viruses using the coating material. To do.

The coating material of the present disclosure comprises a base material in which at least a part of the surface is composed of a coating layer having a reflectance of light having a wavelength of 555 nm of 85% or more, and a photocatalyst layer located on the coating layer. Including.

In the method for inactivating a bacterium or a virus of the present disclosure, the photocatalyst is activated by irradiating the photocatalyst layer of the coating material with light to inactivate the bacterium or the virus.

According to the coating material of the present disclosure, light can be efficiently reached to the photocatalyst, the photocatalytic action can be efficiently exerted, and when the coating material of the present disclosure is used, bacteria or viruses can be inactivated. it can.

FIG. 1 is a schematic cross-sectional view showing a covering material according to the first embodiment. FIG. 2 is a schematic explanatory view showing a case where the covering material shown in FIG. 1 is irradiated with light. FIG. 3 is a schematic cross-sectional view showing the covering material according to the second embodiment. FIG. 4 is a schematic explanatory view showing a case where the covering material shown in FIG. 3 is irradiated with light. FIG. 5 is a graph showing the percentage of the color difference ΔE with respect to the elapsed time.

1. 1. Outline As shown in FIG. 1, the covering material 1 according to the embodiment of the present disclosure includes a base material 2 and a photocatalyst layer 3. At least a part of the surface of the base material 2 is composed of a coating layer 21 having a reflectance of light having a wavelength of 555 nm of 85% or more. The photocatalyst layer 3 is located on the coating layer 21.

In the coating material 1 of the present embodiment, since the reflectance of light having a wavelength of 555 nm of the coating layer 21 is 85% or more, the coating layer 21 easily reflects light. Since the photocatalyst 30 contained in the photocatalyst layer 3 exhibits a photocatalytic action by visible light, not only the light directly hitting the photocatalyst layer 3 but also the light passing through the photocatalyst layer 3 and reflected by the coating layer 21 is used as a photocatalyst. It can reach 30. Therefore, the light can reach the photocatalyst 30 efficiently, and the photocatalytic action can be efficiently exhibited.

In the following description, "reflectance" refers to the gloss of the reference surface by measuring the reflectance of light according to the 60-degree mirror glossiness measuring method described in JIS K 5600-4-7 (1999). It is defined as a percentage when the degree is 100. The upper limit of the mirror glossiness is 100%.

2. Details of covering material 2-1. First Embodiment 2-1-1. Configuration of Covering Material The details of the configuration of the coating material 1 according to the first embodiment will be described below. The coating material 1 according to the first embodiment includes a base material 2 and a photocatalyst layer 3, and further includes an intermediate protective layer 4 provided between the base material 2 and the photocatalyst layer 3. Therefore, in the coating material 1, the intermediate protective layer 4 and the photocatalyst layer 3 are laminated in this order on the base material 2.

(1) Base material The base material 2 is composed of a coating layer 21 at least a part of its surface. That is, the entire surface of the base material 2 may be composed of the coating layer 21, or a part of the surface of the base material 2 may be composed of the coating layer 21. In the present embodiment, the entire surface of the base material 2 is composed of the coating layer 21. The base material 2 includes a base material 20, a coating layer 21, and an undercoat layer 23 provided between the base material 20 and the coating layer 21.

(I) Base material The material of the base material 20 is not particularly limited. The base material 20 can be formed from, for example, one or more materials selected from the group consisting of ceramic materials such as metals and ceramic materials, hydraulic materials such as cement, resin molding materials such as plastics, and carbon materials. When the base material 20 is a metal plate, examples of the metal plate include a steel plate, a stainless plate, an aluminum plate, a zinc plate, a copper plate, and an alloy plate thereof.

The base material 20 of this embodiment is a plated steel plate 22. That is, the base material 2 includes a plated steel plate 22 and a coating layer 21 provided on the plated steel plate 22.

Examples of the plated steel sheet 22 include hot-dip galvanized steel sheets, electrogalvanized steel sheets, alloyed hot-dip galvanized steel sheets, aluminum-plated steel sheets, aluminum-zinc alloy-plated steel sheets, zinc-aluminum-magnesium alloy-plated steel sheets, and zinc-aluminum-magnesium. -Includes various plated steel sheets such as silicon alloy plated steel sheets, galvanized magnesium alloy plated steel sheets, tin plated steel sheets, lead plated steel sheets, and chrome plated steel sheets.

The surface of the plated steel sheet 22 may be subjected to chemical conversion treatment. Examples of chemical conversion treatments include coating chromate treatment, electrolytic chromate treatment, zinc phosphate treatment, and recently developed hexavalent chromium-free non-chromate treatment.

(Ii) Undercoat layer 23
The undercoat layer 23 is provided on the base material 20. The undercoat layer 23 covers the base material 20. Therefore, the undercoat layer 23 is in direct contact with the base material 20. In the present embodiment, since the base material 20 is the plated steel sheet 22, the undercoat layer 23 is in direct contact with the plated steel sheet 22. The undercoat layer 23 may be a single layer or may be composed of a plurality of layers. Further, the case is not limited to the case where the base material 20 and the undercoat layer 23 are in direct contact with each other, and for example, an appropriate layer may be interposed between the base material 20 and the undercoat layer 23. The undercoat layer 23 can be formed from the undercoat paint.

The film thickness of the undercoat layer 23 is preferably 5 μm or more and 30 μm or less. When the film thickness of the undercoat layer 23 is 5 μm or more, the workability of the undercoat layer 23, the adhesion to the base material 20, and the reflectivity of the coating layer 21 can be improved. When the film thickness of the undercoat layer 23 is 30 μm or less, it is possible to suppress the generation of armpits (small swells and holes in the shape of bubbles) when the undercoat paint is applied. The film thickness of the undercoat layer 23 is more preferably 10 μm or more and 25 μm or less, and particularly preferably 12 μm or more and 22 μm or less. If the undercoat paint cannot be applied at one time due to the occurrence of armpits or the like, it may be applied in two or more times.

The undercoat paint can contain, for example, a polyester resin, a curing agent, and a white pigment. The undercoat paint may include pigment components such as extender pigments, coloring pigments and chromate-based or chromate-free rust preventive pigments, curing catalysts, pigment dispersants, surface conditioners, matting agents, organic solvents, etc., as required. A known material may be contained within a range that does not impair the reflectance of light at 555 nm of 85% or more.

The number average molecular weight of the polyester resin contained in the undercoat paint is preferably 2,000 or more and 30,000 or less, and more preferably 3,000 or more and 25,000 or less, from the viewpoint of the finishability of the coating film, the hardness of the coating film, and the processability. It is more preferably 19000 or more and 26000 or less, and even more preferably 20000 or more and 23000 or less. The number average molecular weight in the present specification is a value obtained by converting the number average molecular weight measured using a gel permeation chromatograph (GPC) with reference to the molecular weight of standard polystyrene. Specifically, "HLC8120GPC" (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL" and "TSKgel G-2500HXL" are used as columns. It is possible to measure under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow velocity 1 mL / min and detector RI using four "TSKgel G-2000HXL" (trade name, all manufactured by Tosoh Corporation).

The polyester resin contained in the undercoat paint preferably has a hydroxyl group. The hydroxyl value of the polyester resin is preferably in the range of 10 to 200 mgKOH / g, particularly 60 to 185 mgKOH / g, from the viewpoint of the adhesion of the obtained coating film. The acid value of the polyester resin is preferably in the range of 30 mgKOH / g or less, preferably 1 to 20 mgKOH / g from the viewpoint of finishability.

The polyester resin contained in the undercoat paint can usually be produced by an esterification reaction or a transesterification reaction with a polybasic acid component and a polyhydric alcohol component. As the polybasic acid component, for example, an alicyclic polybasic acid component, an aliphatic polybasic acid component, an aromatic polybasic acid component and the like can be used.

The alicyclic polybasic acid component generally includes a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two or more carboxyl groups in one molecule, and an acid anhydride of the compound. And an esterified product of the compound. Examples of the alicyclic polybasic acid component include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-. Alicyclic polyvalent carboxylic acids such as methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid Anhydrous of these alicyclic polyvalent carboxylic acids; lower alkyl esterified products of these alicyclic polyvalent carboxylic acids and the like. The alicyclic polybasic acid component can be used alone or in combination of two or more.

Examples of the alicyclic polybasic acid component include 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 4-cyclohexene-. 1,2-Dicarboxylic acid and 4-cyclohexane-1,2-dicarboxylic acid anhydride can be preferably used. Of the above, 1,2-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic acid anhydride can be particularly preferably used from the viewpoint of hydrolysis resistance.

The aliphatic polybasic acid component is generally an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound, for example, Kohaku. Aliphatic polyvalent carboxylic acids such as acids, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid, citric acid; Anhydrous of valent carboxylic acid; lower alkyl esterified products of these aliphatic polyvalent carboxylic acids and the like. The aliphatic polybasic acid component can be used alone or in combination of two or more.

As the aliphatic polybasic acid component, it is preferable to use a dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms. Examples of the dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid and the like. Among them, adipic acid can be preferably used.

The aromatic polybasic acid component is generally an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound, and a lower alkyl esterified product of the aromatic compound. For example, aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid; anhydrides of these aromatic polyvalent carboxylic acids. Examples thereof include lower alkyl esterified products of these aromatic polyvalent carboxylic acids. The aromatic polybasic acid component can be used alone or in combination of two or more.

As the polyhydric alcohol component, a polyhydric alcohol having two or more hydroxyl groups in one molecule can be preferably used. Examples of the polyhydric alcohol component (a2) include alicyclic diols, aliphatic diols, aromatic diols, and trihydric or higher polyhydric alcohols.

The alicyclic diol is generally a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two hydroxyl groups in one molecule. Examples of the alicyclic diol include dihydric alcohols such as 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F; these dihydric alcohols include ε-caprolactone and the like. Examples thereof include polylactone diols to which a lactone compound is added, and these can be used alone or in combination of two or more.

The aliphatic diol is generally an aliphatic compound having two hydroxyl groups in one molecule. Examples of the aliphatic diol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, and 2,3. -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol , 1,4-Pentanediol, 2,4-Pentanediol, 2,3-Dimethyltrimethylene glycol, Tetramethylene glycol, 3-Methyl-1,5-Pentanediol, 2,2,4-trimethyl-1,3 -Pentandiol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12- Dodecanediol, neopentyl glycol; polyetherdiol compounds such as polyethylene glycol, polypropylene glycol and polybutylene glycol can be mentioned, and these can be used alone or in combination of two or more.

The aromatic diol is generally an aromatic compound having two hydroxyl groups in one molecule. Examples of the aromatic diol include ester diol compounds such as bis (hydroxyethyl) terephthalate; and alkylene oxide adducts of bisphenol A, which can be used alone or in combination of two or more.

Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, and mannit. Trivalent or higher alcohols; polylactone polyol compounds obtained by adding a lactone compound such as ε-caprolactone to these trihydric or higher alcohols; tris (2-hydroxyethyl) isocyanurate, tris (2-hydroxypropyl) isocyanurate, Examples thereof include tris (hydroxyalkyl) isocyanurate such as tris (2-hydroxybutyl) isocyanurate. Of these, trimethylolpropane is particularly preferable.

The method for producing the polyester resin is not particularly limited, but for example, the acid component containing the polybasic acid component as an essential component and the polyhydric alcohol component are reacted in a nitrogen stream at 150 to 250 ° C. for 5 to 10 hours. , Can be produced by performing an esterification reaction or a transesterification reaction. In this esterification reaction or transesterification reaction, the acid component and the alcohol component may be added at once, or may be added in several times. Further, after first synthesizing the carboxyl group-containing polyester resin, a part of the carboxyl groups in the carboxyl group-containing polyester resin may be esterified using the alcohol component. Further, the polyester resin may be first synthesized and then reacted with an acid anhydride to form a half ester.

In the case of the above esterification or transesterification reaction, a catalyst may be used to accelerate the reaction. As the catalyst, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used.

Further, the polyester resin can be modified with a fatty acid, a fat or oil, a monoepoxy compound, a monoalcohol compound, a polyisocyanate compound or the like during the preparation of the resin, or after the transesterification reaction or the transesterification reaction.

Examples of the fatty acids include palm oil fatty acid, cotton seed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, and dehydrated castor bean paste. Fatty acids such as oil fatty acids and safflower fatty acids; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and the like can be mentioned.

Examples of fats and oils include coconut oil, cottonseed oil, hemp seed oil, rice bran oil, fish oil, tall oil, soybean oil, flaxseed oil, tung oil, rapeseed oil, castor oil, dehydrated castor oil, safflower oil and the like.

Examples of the polyisocyanate compound used for the above modification include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, and methylcyclohexane. Alicyclic diisocyanate compounds such as −2,6-diisocyanate, 4,4′-methylenebis (cyclohexylisocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatics such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Diisocyanate compound; organic polyisocyanate such as trivalent or higher valent polyisocyanate such as lysine triisocyanate itself, or an adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin, water, etc., or each of the above. Examples thereof include cyclized polymers of organic diisocyanates (for example, isocyanurates), billet-type adducts, and the like. These can be used alone or in combination of two or more.

The ratio of the polyester resin to the total amount of the resin contained in the undercoat coating is more preferably 85% by mass or more and 100% by mass or less, and particularly preferably 90% by mass or more and 100% by mass or less.

The curing agent contained in the undercoat paint can be used without particular limitation as long as it can be cured by reacting with the hydroxyl group of the polyester resin by heating. For example, melamine resin, benzoguanamine resin, urea resin and poly Examples thereof include isocyanate compounds.

As the melamine resin, a part or all of the methylol group of methylolated melamine is a monohydric alcohol having 1 to 8 carbon atoms, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol. , I-Butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like, and examples thereof include partially etherified or fully etherified melamine resins that have been etherified.

Commercially available melamine resins include, for example, Cymel 202, Cymel 232, Cymel 235, Cymel 238, Cymel 254, Cymel 266, Cymel 267, Cymel 272, Cymel 285, Cymel 301, Cymel 303, Cymel 325, Cymel 327, Cymel 350. , Cymel 370, Cymel 701, Cymel 703, Cymel 1141 (all manufactured by Daicel Ornex), Uban 20SE60 (manufactured by Mitsui Chemicals, Inc.) and the like.

Examples of the benzoguanamine resin include methylolated benzoguanamine resin obtained by reacting benzoguanamine with an aldehyde. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. The benzoguanamine resin also includes a methylolated benzoguanamine resin etherified with one or more alcohols. Examples of the alcohol used for etherification include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol and 2-ethylhexanol. .. Of these, a benzoguanamine resin obtained by etherifying at least a part of the methylol groups of the methylolated benzoguanamine resin with a monohydric alcohol having 1 to 4 carbon atoms is preferable.

Specific examples of the benzoguanamine resin include, for example, Mycoat 102, Mycoat 105, Mycoat 106 (all of which are manufactured by Mitsui Chemicals, Inc.), Nicarac SB-201, Nicarac SB-203, Nicarac SB-301, and Nicarac SB. Methyl etherified benzoguanamine resin such as −303 and Nicarac SB-401 (both manufactured by Sanwa Chemical Co., Ltd.); Mixed etherified benzoguanamine resin containing methyl ether and ethyl ether such as Cymel 1123 (manufactured by Daicel Ornex); Mixed ether of methyl ether and butyl ether such as Mycoat 136 (manufactured by Mitsui Chemicals, Inc.), Nicarac SB-255, Nicarac SB-355, Nicarac BX-37, Nicarac BX-4000 (all manufactured by Sanwa Chemical Co., Ltd.) Chemicalized benzoguanamine resin; butyl etherified benzoguanamine resin such as Mycoat 1128 (manufactured by Mitsui Chemicals, Inc.) can be mentioned.

The urea resin is obtained by a condensation reaction of urea and formaldehyde, and can be dissolved or dispersed in a solvent or water.

Examples of the polyisocyanate compound include compounds having two or more isocyanate groups in one molecule, for example, aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; tetramethylene diisocyanate, hexamethylene diisocyanate, and dimer. Aliphatic diisocyanates such as acid diisocyanate and lysine diisocyanate; alicyclic diisocyanates such as methylenebis (cyclohexylisocyanate), isophorone diisocyanate, methylcyclohexanediisocyanate, cyclohexanediisocyanate and cyclopentane diisocyanate; buillette type adducts of the polyisocyanate, isocyanul ring type Additives: Free isocyanate group-containing prepolymers formed by reacting these polyisocyanates with low molecular weight or high molecular weight polyol compounds (for example, acrylic polyols, polyester polyols, polyether polyols, etc.) in excess of isocyanate groups. Can be done.

Further, as the polyisocyanate compound, the free isocyanate group of the polyisocyanate compound is used as a phenol compound, an oxime compound, an active methylene compound, a lactam compound, an alcohol compound, a mercaptan compound, an acid amide compound, an imide compound, an amine compound, or imidazole. Blocked polyisocyanate compounds sealed with a blocking agent such as a system compound, a urea compound, a carbamate compound, and an imine compound can also be used.

Further, in order to accelerate the curing of the undercoat resin binder, a curing catalyst can be added as needed. Examples of the curing catalyst when the curing agent is an amino resin include strong acids and neutralized products of strong acids, and typical examples thereof include p-toluene sulfonic acid, dodecylbenzene sulfonic acid, dinonylnaphthalene sulfonic acid, and di. Examples thereof include sulfonic acid compounds which are strong acids such as nonylnaphthalenedisulfonic acid, and amine-neutralized products of these sulfonic acid compounds.

When the curing agent is a blocked polyisocyanate compound, the curing catalyst is a curing catalyst that promotes dissociation of the blocking agent of the blocked polyisocyanate compound, which is a curing agent, for example, tin octylate or dibutyltin di (2-ethyl). Hexanoate), dioctyltin di (2-ethylhexanoate), dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, organic metal catalysts such as lead 2-ethylhexanoate and the like can be mentioned.

As described above, the undercoat paint preferably contains a white pigment. In this case, the reflectance of the coating layer 21 can be improved. The undercoat paint preferably contains titanium oxide as a white pigment, and more preferably contains rutile-type titanium oxide. Since the rutile-type titanium oxide has a high refractive index, the reflectance of the coating layer 21 can be further improved. In the undercoat paint, the solid content volume concentration of rutile-type titanium oxide is preferably 20% or more and 35% or less, more preferably 20% or more and 30% or less, and particularly preferably 22% or more and 28% or less. The average particle size of rutile-type titanium oxide contained in the undercoat coating is preferably 200 nm or more and 400 nm or less, and more preferably 250 nm or more and 350 nm or less. The average particle size of rutile-type titanium oxide was observed by magnifying the undercoat layer 23 10,000 times with an electron microscope, and 20% from the smaller particle size and 5% from the larger particle size were excluded. It is an arithmetic mean value of the particle size of the remaining rutile-type titanium oxide.

There are no particular restrictions on the method for producing titanium oxide, the presence or absence or type of surface treatment, etc., but those with as high a concealing property and high whiteness as possible are preferable, and in particular, rutile-type titanium oxide is produced by the chlorine method and is also produced. , Alumina, silica, titania and the like are preferably surface-treated. Such titanium oxide is particularly preferable because it has high hiding power and whiteness.

Examples of commercially available titanium oxide products include Ti-Pure R706, Ti-Pure R960, Ti-Pure R902 + (above, manufactured by DuPont, trade name, titanium oxide pigment by chlorine method), Typake CR-50, and Typake CR-. 60, Typake CR-95 (manufactured by Ishihara Sangyo Co., Ltd., trade name, titanium oxide pigment by chlorine method), CR-826 (manufactured by Tronox, trade name, titanium oxide pigment by chlorine method) and the like.

The undercoat paint may contain a solvent, a leveling agent, a pigment dispersant, an armpit inhibitor, and the like in order to improve coating workability.

As a method of applying the undercoat paint, curtain coating, roll coating, immersion coating, spray coating and the like can be adopted. When the undercoat coating is precoated by coil coating, it is preferable to adopt the curtain coating method and the roll coating method because of its economic efficiency. When applying the roll coating method, a top feed or bottom feed method using three rolls is recommended in order to maximize the uniformity of the coated surface, but in practice, a normal bottom feed method using two rolls ( So-called natural reverse coating, natural coating) may be used.

The curing conditions (baking conditions) of the undercoat paint are usually about 15 seconds to 30 minutes at a material reaching maximum temperature (PMT) of 120 to 260 ° C. In the field of pre-coating coating, in which coating is performed by coil coating or the like, the coating is usually performed at a maximum material reaching temperature of 160 to 260 ° C. for 15 to 90 seconds.

(2) Coating layer The coating layer 21 is provided on the undercoat layer 23 and covers the undercoat layer 23. Therefore, the coating layer 21 covers the base material 20 and constitutes the surface of the base material 2. The coating layer 21 contains a binder and a white pigment. The coating layer 21 of the present embodiment is in direct contact with the undercoat layer 23, but the present invention is not limited to this, and an appropriate layer may be interposed between the undercoat layer 23 and the coating layer 21.

The coating layer 21 has a high reflectance of light. Specifically, the coating layer 21 has a reflectance of light having a wavelength of 555 nm of 85% or more. This configuration can be achieved, for example, by the coating layer 21 containing a high concentration of white pigment relative to the binder. When the concentration of the white pigment with respect to the binder in the coating layer 21 is high, reflection is likely to occur not only at the white pigment-binder interface but also at the white pigment-air interface and the binder-air interface. Therefore, the light reflectance of the coating layer 21 can be increased. Further, it is preferable that the coating layer 21 has a reflectance of light having a wavelength of 450 nm or more and 750 nm or less of 92.5% or more and a reflectance of light having a wavelength of 555 nm of 95% or more. In this case, the coating layer 21 can efficiently reflect light. Further, when the covering material 1 is used as a reflector, high illuminance can be obtained.

The coating layer 21 of the present embodiment will be described in more detail.

In the coating layer 21, the concentration of the white pigment is preferably 150 parts by volume or more, more preferably 200 parts by volume or more, further preferably 500 parts by volume or more, still more preferably 800 parts by volume or more with respect to 100 parts by volume of the binder. In this case, the reflectance of the coating layer 21 can be improved without thickening the coating layer 21. The concentration of the white pigment is preferably less than 1500 parts by volume with respect to 100 parts by volume of the binder. In this case, it is possible to prevent the coating layer 21 from becoming brittle, and it is possible to secure the strength of the coating layer 21.

The porosity of the coating layer 21 by volume is preferably 5 vol% or more, more preferably 9 vol% or more, and further preferably 20 vol% or more. Further, the porosity in the cross section is preferably 2% or more, more preferably 5% or more, still more preferably 10% or more. In this case, the reflectance of the coating layer 21 can be improved without thickening the coating layer 21. The coating layer 21 preferably has a porosity of less than 35 vol% by volume. The porosity in the cross section is preferably less than 35%. In this case, in this case, it is possible to prevent the coating layer 21 from becoming brittle, and it is possible to secure the strength of the coating layer 21.

The concentration (volume part) of the binder and the white pigment in the coating layer 21 and the porosity by volume can be measured by the following methods. First, a part of the coating layer 21 is scraped off to confirm the components of the binder and the white pigment. The method for confirming the components is not particularly limited. For example, the binder component can be confirmed by a method such as FT-IR or NMR. For example, the component of the white pigment can be confirmed by a method such as XRD or FT-IR. Next, a sample having a constant area a and a constant thickness b is scraped from the coating layer 21. The apparent volume c of this sample is a × b. Next, the mass d of the sample is measured with a weighing machine capable of measuring with an effective number of digits of 3 or more. The entire sample is then heated until the binder decomposes. Next, the mass e of the sample after heating is measured. The mass e corresponds to the mass of the white pigment, and the mass f of the binder can be calculated by subtracting the mass e from the mass d. The volume g of the binder and the volume h of the white pigment that occupied the volume c can be calculated based on the specific gravity of the components of these binders, the mass f of the binder, the specific gravity of the components of the white pigment, and the mass e of the white pigment. it can. Further, from these values, the concentration (volume part) of the binder and the white pigment and the porosity by volume can be obtained.

The porosity in the cross section of the coating layer 21 can be measured by the following method. First, the sample scraped from the coating layer 21 is embedded in a resin and polished to form a cross section perpendicular to the surface of the coating layer 21 and smooth. This cross section is photographed with a scanning microscope at a magnification of 10000 times. By comparing the area of the white pigment and the area of the voids in the obtained image, the porosity of the cross section can be obtained.

The thickness of the coating layer 21 is preferably 5 μm or more and less than 100 μm. When the thickness of the coating layer 21 is less than 100 μm, it is possible to prevent the coating layer 21 from becoming brittle. The thickness of the coating layer 21 is preferably 20 μm or more and 50 μm or less, and more preferably 25 μm or more and 35 μm or less from the viewpoint of appearance finish. In this case, the light reflectance of the coating layer 21 can be improved, the brittleness of the coating layer 21 can be suppressed, and the strength of the coating layer 21 can be ensured. The coating layer 21 is not limited to the case where it is composed of a single layer, and may be composed of a plurality of layers.

The binder contained in the coating layer 21 may be a thermoplastic resin or a thermosetting resin. The binder may be a heat-melted solid resin, a resin dissolved in an organic solvent, or a crushed solid resin. The binder may be water-soluble or an emulsion type in which water is dispersed. The binder may be an ultraviolet curable resin or an electron beam curable resin. The binder may contain a cross-linking agent. The binder may contain, for example, one or more selected from the group consisting of polyester resin, urethane resin, acrylic resin, epoxy resin, melamine resin, vinyl chloride resin, fluororesin, and silicone resin.

The white pigment contained in the coating layer 21 preferably contains rutile-type titanium oxide. That is, it is preferable that the coating layer 21 contains rutile-type titanium oxide. Since rutile-type titanium oxide has a high refractive index, it easily reflects light at the white pigment-binder interface. Therefore, when the coating layer 21 contains rutile-type titanium oxide as a white pigment, the light reflectance of the coating layer 21 can be improved. The rutile-type titanium oxide may be surface-treated with Al, Si, Zr, an organic substance or the like. The coating layer 21 may contain a commercially available rutile-type titanium oxide as a white pigment. Examples of commercially available rutile-type titanium oxide include the "Typake TM" series manufactured by Ishihara Sangyo Co., Ltd., the "Titanics" series manufactured by TAYCA Corporation, and the like. The coating layer 21 may contain a white pigment other than rutile-type titanium oxide.

The average particle size of the white pigment contained in the coating layer 21 is preferably 200 nm or more and 400 nm or less. In this case, the surface area of the white pigment can be increased, the reflectance of the coating layer 21 can be improved, and the increase in the transmittance of light on the long wavelength side can be suppressed.

The coating layer 21 can be formed from a coating coating material containing the above-mentioned binder and white pigment. Specifically, the coating layer 21 is obtained by baking and drying the coating film of the coating paint. Examples of coating method coating methods include roller curtain coating, curtain flow coating, air spray coating, die coater coating, immersion coating, inkjet coating and the like.

(3) Intermediate Protective Layer The intermediate protective layer 4 is provided between the base material 2 and the photocatalyst layer 3, and more specifically, is provided between the coating layer 21 and the photocatalyst layer 3. Therefore, the intermediate protective layer 4 covers the coating layer 21 and is in direct contact with the coating layer 21.

The main component of the intermediate protective layer 4 is preferably silicon oxide or a siloxane polymer.

Silicon oxide includes at least one selected from the group consisting of silicon monoxide, silicon dioxide, and compounds in which the ratio of silicon to oxygen is not constant (eg, SiO _1.5 , SiO _1.8 ). The silicon oxide may be crystalline, amorphous, or quasicrystalline. The silicon oxide preferably contains amorphous silica. In this case, the flexibility of the intermediate protective layer 4 can be improved as compared with the case where the silicon oxide is crystalline silica.

The siloxane polymer includes a tetraalkoxysilane having an alkoxy group having 1 to 4 carbon atoms, an alkoxysilane having an alkyl group having 1 to 12 carbon atoms, an alkoxysilane having an aryl group, and an alkyl group having 1 to 12 carbon atoms. Dehydration obtained by a hydrolysis reaction of at least one alkoxysilane selected from the group consisting of alkoxysilanes having both aryl groups and an alkoxysilane having an epoxy group or an alkoxysilane having an amino group, and a subsequent condensation reaction. It preferably contains a condensate. As the condensate of alkoxysilane, it is preferable that the alkoxysilane used as a raw material is hydrolyzed to once produce a hydrolyzate, and then condensed in a drying baking (heat treatment) step. When the main component of the intermediate protective layer 4 is silicon oxide or a siloxane polymer, it is preferable to suppress deterioration of the intermediate protective layer 4 due to the photocatalytic action of the photocatalyst 30 contained in the photocatalyst layer 3. In particular, the main component of the intermediate protective layer 4 is an inorganic-organic composite polymer in which a large amount of alkyl groups and aryl groups are mixed with a polysiloxane-based inorganic polymer containing amorphous silica or silicon as a main component. The weather resistance, processability, and stability to a photopolymer of 4 can be improved.

The above-mentioned alkyl group having 1 to 12 carbon atoms includes a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a 2-ethylhexyl group and a dodecyl group, and the aryl group includes a phenyl group, a tolyl group and a xylyl group. Examples include groups and naphthyl groups. Among these alkyl groups, a methyl group and a phenyl group are preferable. That is, the alkoxysilane having an alkyl group having 1 or more and 12 or less carbon atoms preferably contains an alkoxysilane having a methyl group, an alkoxysilane having a phenyl group, and an alkoxysilane having a methyl group and a phenyl group, and has a phenyl group. It is particularly preferable to include alkoxysilane. The siloxane polymer preferably contains two or more types of alkoxysilanes having different organic groups and alkoxysilanes containing two or more different organic groups.

When the intermediate protective layer 4 contains the above-mentioned inorganic-organic composite polymer, the inorganic-organic composite polymer has a methyl group and / or a ratio of 0.05 to 1.5 with respect to 1 bond of Si—O. The phenyl group is preferably bonded, and more preferably the phenyl group is bonded at a ratio of 0.05 to 1.2. In this case, it is possible to impart appropriate flexibility to the intermediate protective layer 4 and improve the photocatalytic activity of the photocatalytic layer 3 provided on the intermediate protective layer 4.

The intermediate protective layer 4 may contain a photocatalyst. In this case, the proportion of the photocatalyst in the intermediate protective layer 4 is preferably smaller than the proportion of the photocatalyst in the photocatalyst layer 3. The mass ratio of the photocatalyst to the entire intermediate protective layer 4 is preferably 0.05% or more and 20% or less, and more preferably 0.1% or more and 15% or less. In this case, even if the intermediate protective layer 4 is exposed due to deterioration of the photocatalytic layer 3, the photocatalyst contained in the intermediate protective layer 4 can exhibit a photocatalytic action. Further, deterioration of the resin contained in the coating layer 21 due to the photocatalytic action of the photocatalyst contained in the intermediate protective layer 4 can be suppressed.

The thickness of the intermediate protective layer 4 is preferably 0.1 μm or more and 3 μm or less, more preferably 0.1 μm or more and 2.5 μm or less, and even more preferably 0.3 μm or more and 2 μm or less.

The intermediate protective layer 4 can be formed by forming a coating film from the coating film for a protective layer containing the above-mentioned silicon oxide or siloxane polymer and, if necessary, a photocatalyst, and then heat-curing the coating film. As a method for applying the coating material for the protective layer, for example, a dip coating method, a spray coating method, a bar coating method, a roll coating method, or a spin coating method can be adopted. The heating condition of the coating film of the protective layer coating film is preferably heat treatment for about 1 hour to several seconds in a temperature range of about 150 ° C. or higher and about 400 ° C.

(4) Photocatalyst layer The photocatalyst layer 3 is located on the coating layer 21, and more specifically, on the intermediate protective layer 4.

The photocatalyst layer 3 preferably contains at least one of silicon oxide and a siloxane polymer.

The silicon oxide preferably contains, for example, amorphous silica.

The siloxane polymer preferably contains, for example, a tetraalkoxysilane having an alkoxy group having 1 or more and 4 or less carbon atoms, or a resin composed of a dehydration condensate obtained by a hydrolysis reaction and a condensation reaction of the alkoxysilane having an epoxy group.

Examples of tetraalkoxysilanes having an alkoxy group having 1 to 4 carbon atoms include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, and tetra-. Includes i-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane and the like.

Examples of alkoxysilanes having an epoxy group include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane. , 3,4-Epylcyclohexylmethyltrimethoxysilane, 3,4-epylcyclohexylmethyltriethoxysilane, β- (3,4-epylcyclohexyl) ethyltrimethoxysilane, and β- (3,4-epoxycyclohexyl) ethyl Includes triethoxysilane and the like. Among the alkoxysilanes having an epoxy group, γ-glycidoxypropyltriethoxysilane is particularly excellent in handleability.

The above-mentioned resin composed of a condensate of alkoxysilane and alkoxysilane is a resin having high stability to a photocatalyst mainly composed of siloxane, which is an inorganic component, and mainly composed of an inorganic component containing a small amount of epoxy group. Of these, an alkoxysilane having an epoxy group is preferable because it has the effect of lowering the baking temperature of the film. Generally, when a polysiloxane-based film is formed using only silicon alkoxide as a starting material, heat treatment at 400 to 500 ° C. for several hours is required in order to efficiently carry out a series of steps from dehydration condensation to curing. .. By introducing an epoxy group in forming the photocatalyst layer 3, it is possible to reduce the treatment temperature of about 150 to 200 ° C. and the heat treatment time, and the heat treatment conditions can be set so that coil coating is possible.

The photocatalyst layer 3 preferably contains an inorganic polymer consisting only of tetraalkoxysilane and a condensate of these alkoxysilanes. In tetraalkoxysilane, a siloxane bond containing a hydroxyl group is formed by hydrolysis and dehydration condensation, and further aging or heat treatment can result in only a siloxane bond, and the photocatalytic layer 3 is deteriorated by the photocatalytic action of the photocatalyst 30. It can be suppressed.

The ratio of the epoxy group contained in the photocatalyst layer 3 is preferably 0 to 0.25 with respect to the bond 1 of Si—O, and more preferably 0 to 0.22. In this case, the photocatalyst resistance of the photocatalyst layer 3 can be improved.

The photocatalyst layer 3 contains the photocatalyst 30. The photocatalyst 30 is a substance that exhibits a photocatalytic action when irradiated with light. Specific examples of the photocatalyst 30 include titanium oxide. Examples of titanium oxide include rutile-type titanium oxide, anatase-type titanium oxide, and brookite-type titanium oxide. The photocatalyst 30 preferably contains anatase-type titanium oxide. That is, the photocatalyst layer 3 preferably contains anatase-type titanium oxide. This is because the photocatalytic activity of anatase-type titanium oxide is higher than that of other titanium oxides. In particular, the photocatalyst 30 is preferably a substance that exhibits a photocatalytic action by visible light. That is, the photocatalyst 30 is preferably a visible light excitation type photocatalyst. In this case, the photocatalytic action of the photocatalyst 30 can be expressed by visible light, and the photocatalytic action of the photocatalyst 30 can be expressed by the light of, for example, a fluorescent lamp or an LED. Examples of the visible light excitation type photocatalyst include anatase type titanium oxide doped with anions such as nitrogen and sulfur, and anatase type titanium oxide supported with Pt particles.

When nitrogen is doped into a titanium oxide crystal, depending on the presence of nitrogen, (i) a part of the oxygen site of the titanium oxide crystal is replaced with a nitrogen atom and has a Ti—ON composition, (ii) oxidation. One or more of those in which nitrogen atoms are present between the lattices of titanium crystals and those in which nitrogen atoms are present at the grain boundaries of the polycrystal aggregate of (iii) titanium oxide crystals can be obtained. In particular, since the crystal structure of the photocatalyst (i) is stabilized by the Ti—ON structure, the photocatalytic action can be exhibited by both visible light and ultraviolet rays, and the photocatalytic action can be exhibited for a long period of time. Can be expressed.

The state of the photocatalyst 30 may be any of powder, an aqueous sol or colloid dispersed in water, an organic solvent-based sol or colloid dispersed in a polar solvent such as alcohol, or a non-polar solvent such as toluene. When the photocatalyst 30 is an organic solvent-based sol or colloid, the photocatalyst coating material may be diluted with water or an organic solvent depending on its dispersibility. Further, the photocatalyst 30 may be surface-treated in order to improve the dispersibility of the photocatalyst 30.

When the photocatalyst 30 contains nitrogen-doped anatase-type titanium oxide, it can be produced, for example, by the following methods (I) to (IV).
(I) A method for heat-treating titanium oxide or titanium hydroxide in an atmosphere containing at least one gas selected from the group consisting of ammonia gas, nitrogen gas, and a mixed gas of nitrogen gas and hydrogen gas.
(II) A method for heat-treating a titanium alkoxide solution in an atmosphere containing at least one gas selected from the group consisting of ammonia gas, nitrogen gas, and a mixed gas of nitrogen gas and hydrogen gas.
(III) In the emulsion combustion method, ions or molecules containing nitrogen elements other than nitrate ions, such as ammonia and hydrazine, are present in the aqueous titanium salt solution or suspension, which is the aqueous phase in the emulsion, and are contained in the emulsion. The reactor contains less oxygen than the amount of oxygen required for the combustion components including oil and surfactant to burn completely and the metal ions or metal compounds contained in the aqueous solution to form the most stable oxide in the atmosphere. A method of spray-burning an emulsion in the atmosphere introduced inside.
(IV) In the emulsion combustion method, ions or molecules containing nitrogen atoms other than nitrate ions, such as ammonia and hydrazine, are not present in the titanium salt aqueous solution or suspension which is the aqueous phase in the emulsion, and nitrogen other than nitrogen gas is contained. A method of spray-burning an emulsion in an atmosphere containing a gas such as ammonia and the amount of oxygen introduced into the reactor is less than the required amount of oxygen.
(V) A method for heat-treating or plasma-treating a titanium nitride crystal or a titanium nitride crystal in an oxidizing atmosphere containing a compound containing oxygen, ozone, water molecules, or a hydroxyl group.
(VI) A method of heating a mixture of titanium oxide and a nitrogen compound adsorbed on titanium oxide at room temperature.

The primary particle size of the photocatalyst 30 is preferably 0.5 μm or less, more preferably 0.1 μm or less, and particularly preferably 0.05 μm or less. The lower limit of the primary particle diameter of the photocatalyst 30 is not particularly limited, but is, for example, 5 nm or more. The smaller the primary particle size of the photocatalyst 30, the better the photocatalytic action. Further, the smaller the primary particle diameter of the photocatalyst 30, the more difficult it is to disperse, and an agglomerate of particles of the photocatalyst 30 is formed. Resin is often absent in the gaps between the aggregates. By forming a region in which the resin does not exist in the photocatalyst layer 3, photocatalytic actions such as antifouling action and inactivating action of bacteria or virus can effectively act.

When the photocatalyst 30 is fine particles, it is difficult to disperse the photocatalyst 30 in the photocatalyst layer 3, and the particles of the photocatalyst 30 may form aggregates. Usually, the resin component constituting the photocatalyst layer 3 does not exist in the gaps between the aggregates, so that there is an advantage that bacteria or viruses can easily reach the photocatalyst 30. Further, in the photocatalyst layer 3, it is desirable that the photocatalyst 30 is uniformly dispersed, but it is not always necessary to uniformly disperse the photocatalyst 30. When the photocatalyst 30 is not uniformly dispersed, when the particles of the photocatalyst 30 form aggregates, when the concentration of the photocatalyst 30 is different between the outermost surface portion and the inside, the content concentration of the photocatalyst substance is stepwise. It can be suitably used even in these states.

By changing the dispersed state of the photocatalyst 30 in the photocatalyst layer 3, the photocatalytic action can be exhibited for a long period of time from the initial stage, and deterioration of the resin contained in the photocatalyst layer 3 can be suppressed. For example, the photocatalyst 30 included in the photocatalyst layer 3 has a maximum particle size distribution, one of the maximum particle size distributions of the photocatalyst 30 is in the range of 0.5 μm to 5 μm, and the intermediate protective layer 4 has a maximum value. It is preferable that one of the maximum values of the particle size distribution of the photocatalyst is 0.2 μm or less. The photocatalyst 30 in the photocatalyst layer 3 preferably has high activity because it exhibits a photocatalytic action, and as a result of the aggregation of fine particles of the photocatalyst 30, one of the maximum values of the particle size distribution is in the range of 0.5 μm to 5 μm. It is preferable to be in. The maximum value of the particle size distribution of the photocatalyst 30 in the photocatalyst layer 3 is more preferably 0.5 μm to 3 μm, further preferably 0.6 μm to 2 μm. The maximum value of the particle size distribution of the photocatalyst in the intermediate protective layer 4 is preferably 0.15 μm or less. The maximum value of the photocatalyst contained in the photocatalyst layer 3 and the intermediate protective layer 4 preferably does not exceed 20 μm, which is twice the total film thickness, and more preferably does not exceed 10 μm. Further, in the photocatalyst layer 3, the maximum value of the particle size distribution of the photocatalyst 30 is preferably less than 0.2 μm. In this case, the photocatalytic activity of the photocatalytic layer 3 can be easily expressed from the initial stage.

The ratio of the photocatalyst 30 contained in the photocatalyst layer 3 is preferably 50% or less, preferably 40% or less, and preferably 30% or less in terms of the mass ratio with respect to the entire photocatalyst layer 3. In this case, deterioration of the resin contained in the photocatalyst layer 3 due to the photocatalytic action of the photocatalyst 30 can be suppressed while efficiently exhibiting the photocatalytic action of the photocatalyst 30. The lower limit of the ratio of the photocatalyst 30 contained in the photocatalyst layer 3 is not particularly limited as long as the photocatalytic action can be exhibited, but for example, 0.05% or more is preferable, 0.2% or more is more preferable, and 0.5%. The above is more preferable.

The photocatalyst layer 3 may contain the photocatalyst 30 as it is, or may contain the photocatalyst 30 in a state of being supported on the surface of the catalyst carrier. When the photocatalyst layer 3 contains a catalyst carrier, the area where the photocatalyst 30 and the polymer component come into direct contact with each other can be reduced, so that deterioration of the polymer component due to the photocatalyst 30 can be suppressed. Further, although it may be difficult to disperse the photocatalyst 30 depending on the polymer component, it is possible to easily disperse the photocatalyst 30 by using an appropriate catalyst alone. The photocatalyst layer 3 preferably contains an inorganic oxide that is stable with respect to the photocatalyst 30 as a catalyst carrier, and is selected from the group consisting of silicon oxide, aluminum oxide, magnesium oxide, zirconium oxide, iron oxide, and calcium oxide. It is preferable to include one or more of the above.

The photocatalyst layer 3 is substantially composed of silicon oxide or a siloxane polymer and a photocatalyst 30. Therefore, if the content of the photocatalyst 30 is about 10%, the rest can be silicon oxide or a siloxane polymer. However, in order to improve the design, corrosion resistance, abrasion resistance, catalytic function, etc. of the photocatalyst layer 3, the photocatalyst layer 3 is composed of a coloring pigment, an extender pigment, a catalyst other than the photocatalyst, a rust preventive pigment, a metal powder, and a high frequency loss agent. , Aggregate, etc. may be included. The photocatalyst layer 3 contains, for example, an oxide such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , a composite oxide containing two or more metal elements as constituents, a metal powder such as Zn powder and Al powder, and the like. Can be done. Further, the photocatalyst layer 3 can contain a non-chromic acid-based rust preventive pigment such as calcium molybdate, calcium phosphomolybate, and aluminum phosphomolybate. Further, the photocatalyst layer 3 can contain Zn—Ni ferrite as a high frequency loss agent. Further, the photocatalyst layer 3 can contain potassium titanate fiber as an aggregate. The amount of these components in the photocatalyst 30 is not particularly limited, but is, for example, preferably 30% or less, more preferably 20% or less, and particularly preferably 15% or less.

The photocatalyst layer 3 contains Si as a main element, but contains one or more elements selected from the group consisting of B, Al, Ge, Ti, Y, Zr, Nb, and Ta as other elements. May be good. In particular, Al, Ti, Nb, and Ta can complete the solidification of the film at a low temperature or in a short time when an acid is added to the system as a catalyst. When these metal-containing alkoxides are added using an acid as a catalyst, the ring-opening rate of the epoxy is increased, and the film can be cured at a low temperature in a short time. The photocatalyst layer 3 preferably contains a Ti alkoxide such as Ti-ethoxide or Ti-isopropoxide. Further, in the system to which Zr is added, the alkali resistance of the film is remarkably improved, and therefore, it is suitably used in applications where alkali resistance is particularly required.

The thickness of the photocatalyst layer 3 is preferably 0.1 μm or more and 3 μm or less, more preferably 0.1 μm or more and 2.5 μm or less, further preferably 0.3 μm or more and 2 μm or less, and particularly preferably 1 μm or more and 3 μm or less. In this case, the photocatalytic action of the photocatalyst 30 contained in the photocatalyst layer 3 can be particularly exhibited.

The total thickness of the photocatalyst layer 3 and the intermediate protective layer 4 is preferably 5 μm or less. In this case, the workability of the covering material 1 and the adhesion of the processed portion can be improved. The total thickness of the photocatalyst layer 3 and the intermediate protective layer 4 is more preferably 4 μm or less, and particularly preferably 3 μm or less. In this case, the workability of the photocatalyst layer 3 and the intermediate protective layer 4 can be improved. The lower limit of the total thickness of the photocatalyst layer 3 and the intermediate protective layer 4 is not particularly limited, but is preferably 0.1 μm or more, and more preferably 0.3 μm or more.

The photocatalyst layer 3 can be formed, for example, by forming a coating film from the photocatalyst coating material containing the above-mentioned silicon oxide or siloxane polymer and the photocatalyst 30, and then heat-curing the coating film. The photocatalyst layer 3 may be formed on the intermediate protective layer 4 after forming the intermediate protective layer 4, and after forming a coating film of the protective layer coating film on the coating film 21, the photocatalyst coating is applied on the coating film. By forming a coating film and heat-curing the two coating films, the intermediate protective layer 4 may be formed at the same time. As a method for applying the photocatalytic paint, for example, a dip coating method, a spray coating method, a bar coating method, a roll coating method, or a spin coating method can be adopted. The heating condition of the coating film of the photocatalytic paint is preferably heat treatment for about 1 hour to several seconds in a temperature range of about 150 ° C. or higher and about 400 ° C.

2-1-2. Photocatalytic action The photocatalytic action expressed by the coating material 1 according to the first embodiment will be described with reference to FIG.

FIG. 2 is a diagram for explaining the photocatalytic action when the photocatalyst layer 3 of the coating material 1 shown in FIG. 1 is irradiated with light. According to FIG. 2, the photocatalytic action is exhibited by the light that reaches the photocatalyst 30. Further, a part of the light irradiated to the photocatalyst layer 3 passes through the photocatalyst layer 3. The light that has passed through the photocatalyst layer 3 passes through the intermediate protective layer 4 and reaches the coating layer 21. Since the coating layer 21 of the present embodiment has a reflectance of light having a wavelength of 555 nm of 85% or more, the light reaching the coating layer 21 is efficiently reflected by the coating layer 21. The light reflected by the coating layer 21 passes through the intermediate protective layer 4 and reaches the photocatalyst layer 3 again. The photocatalytic action is also exhibited by the light reflected by the coating layer 21 and reaching the photocatalytic layer 3. That is, in the coating material 1 of the present embodiment, not only the light directly irradiated to the photocatalyst layer 3 but also the light that has passed through the photocatalyst layer 3 and is reflected by the coating layer 21 can reach the photocatalyst 30. Therefore, light can be efficiently reached to the photocatalyst 30, and the photocatalytic action of the photocatalyst 30 can be efficiently exhibited. As a result, a high photocatalytic action can be exhibited from the initial stage of irradiating the photocatalytic layer 3 with light, and this photocatalytic action can be maintained for a long period of time.

Further, since the photocatalyst 30 of the present embodiment is a visible light excitation type photocatalyst, the photocatalytic action can be exhibited not only by ultraviolet light having a wavelength of 380 nm or less but also by visible light having a wavelength of 400 nm or more. Therefore, in the coating material 1 in the present embodiment, the photocatalytic action can be exhibited not only by sunlight containing a large amount of ultraviolet rays but also by light from fluorescent lamps, xenon lamps, LEDs and the like. In particular, since the coating layer 21 has a high reflectance of light having a wavelength of 555 nm and 555 nm is substantially in the middle of the wavelength in the visible light region (380-750 nm), the light in the entire visible light region can be efficiently reflected. Since the photocatalyst 30 of the present embodiment is a visible light excitation type photocatalyst, the wavelength region of light that is easily reflected by the coating layer 21 and the wavelength region in which the photocatalyst 30 can exhibit a photocatalytic action overlap. Therefore, the photocatalytic action of the photocatalyst 30 can be exhibited by the visible light directly reaching the photocatalyst 30 and the visible light reflected by the coating layer 21, and the photocatalyst is high from the initial stage when the photocatalyst layer 3 is irradiated with visible light. The action can be exhibited and the photocatalytic action can be maintained for a long period of time.

The photocatalytic action expressed in the coating material 1 of the present embodiment includes a hydrophilic action, an antifouling action, an inactivating action of a bacterium or a virus, and the like. In particular, in the present embodiment, the inactivating effect of bacteria or virus is easily exhibited, and the inactivating effect of bacteria or virus is exhibited even at an initial stage as compared with a coating material in which a photocatalyst layer is provided on the surface of a general colored steel sheet. It is made to be able to maintain the inactivating action for a long period of time. This can be achieved when the reflectance of the light having a wavelength of 555 nm of the coating layer 21 is 85% or more, and is more easily achieved when the photocatalyst 30 is a visible light excitation type photocatalyst. Further, the photocatalytic action expressed in the coating material 1 includes antifouling, hydrophilic function, decomposition of organic substances and the like.

2-2. Second Embodiment 2-2-1. Composition of Covering Material The covering material 1 according to the second embodiment is different from the covering material 1 according to the first embodiment in that the covering layer 210 is provided instead of the covering layer 21, and the coating material 1 according to the first embodiment is otherwise provided. It has the same structure as that of the material 1. Therefore, in the coating material 1 of the present embodiment, as shown in FIG. 3, the intermediate protective layer 4 and the photocatalyst layer 3 are laminated in this order on the base material 2. Further, the base material 2 includes a base material 20, a coating layer 210, and an undercoat layer 23 provided between the base material 20 and the coating layer 210. Therefore, in the coating material 1 of the present embodiment, the photocatalyst layer 3 is provided on the coating layer 210.

Like the coating layer 21, the coating layer 210 of the present embodiment has a reflectance of light having a wavelength of 555 nm of 85% or more, but it is particularly preferable that the diffuse reflectance of light having a wavelength of 555 nm is 85% or more. In this case, the light that has passed through the photocatalyst layer and reached the coating layer 210 can be diffused and reflected in a wide range of the photocatalyst layer 3. As a result, a particularly high photocatalytic action can be exhibited from the initial stage when the photocatalyst layer 3 is irradiated with light.

The "diffuse reflectance" is the diffuse reflectance of light having a wavelength of 555 nm, which does not include specular reflection by the integrating sphere. This diffuse reflectance is defined as a percentage when the diffuse reflectance at a wavelength of 555 nm measured using a diffuse reflectance measuring device using an integrating sphere is set to 100 as a reference white plate. Examples of the diffuse reflectance measuring device include "CM-3700d" manufactured by Minolta Co., Ltd. (currently Konica Minolta Co., Ltd.) and "AVAL265" spectrophotometer manufactured by Shimadzu Corporation. Diffuse reflectance is measured in accordance with JIS Z 8722 geometric condition c, etc., and an integrating sphere (a sphere whose inner surface is coated with a white paint such as barium sulfate that diffusely reflects light almost completely) is used. Then, the reflectance at a wavelength of 555 nm is measured as a percentage when the reference white plate (material is barium sulfate) is 100 under the condition of light reception in the diffuse illumination 8 ° direction. For the diffuse reflectance, an SCE (specular reflection light removal) method can be adopted as a method of measuring the light by removing the specularly reflected light. In the SCE method, since the specularly reflected light is removed and only the diffusely reflected light is measured, the evaluation of color and gloss is close to visual observation. The upper limit of the diffuse reflectance of the coating layer 210 is 100%.

Hereinafter, the coating layer 210 will be described in detail.

In the present embodiment, for example, the configuration of the first example or the configuration of the second example shown below can be adopted as the coating layer 210. The configuration of the coating layer 210 is not limited to the configurations of the first example and the second example below.

(First example)
The coating layer 210 of the first example contains a binder resin and a pigment. Therefore, the coating layer 210 is formed from a coating coating material containing a binder resin and a pigment.

The binder resin preferably contains a polyester resin having a number average molecular weight of 19000 or more and 28,000 or less (hereinafter, also referred to as polyester resin A). Since the coating layer 210 of the present embodiment has a high pigment concentration in the coating coating material, it is necessary to secure an ability (binder ability) for retaining the pigment-pigment. In this respect, by blending the polyester resin A as the resin contained in the coating paint, the binder ability can be ensured and the processability of the coating layer 210 can be improved. Further, usually, when a polyester resin having a high number average molecular weight is adopted, the viscosity of the coating paint is increased, so that the solid content concentration in the coating coating tends to be high. On the other hand, in the coating paint of the present embodiment, since the pigment concentration is high and the resin concentration is relatively low, the viscosity suitable for forming the coating film is suitable even if the number average molecular weight of the polyester resin A is in the above range. It is easy to form a coating film from the coating paint. Therefore, it is possible to form a thick coating film from the coating paint while suppressing the generation of armpits (small bulges and holes in the shape of bubbles). Further, when the number average molecular weight of the polyester resin is 19000 or more, excellent moldability can be imparted to the coating material 1. Further, when the number average molecular weight of the polyester resin is 28,000 or less, it is possible to secure the scratch resistance of the coating layer 210 while imparting appropriate flexibility to the coating layer 210. The number average molecular weight of the polyester resin A is more preferably 19000 or more and 26000 or less, and particularly preferably 20000 or more and 23000 or less. The ratio of the polyester resin A to the total amount of the binder resin is preferably 20% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 80% by mass or less, and particularly preferably 40% by mass or more and 60% by mass or less.

The binder resin preferably contains a polyester resin having a number average molecular weight of 2000 or more and 6000 or less and a hydroxyl value of 20 or more (hereinafter, also referred to as polyester resin B). It is conceivable that the coating layer 210 of the present embodiment has a structure in which the resin is dispersed between the pigments. In this structure, by combining the polyester resin A and the polyester resin B, the polyester resin B can enter the gap where the polyester resin A does not easily enter. Therefore, the polyester resin B functions as a binder between the pigment and the pigment, or between the pigment and the polyester resin A, and can improve the strength, processability, and adhesion of the coating layer 210.

Further, when the number average molecular weight of the polyester resin B is 2000 or more, the strength of the coating layer 210 can be ensured, and the workability of the coating layer 210 can be improved. Further, when the number average molecular weight of the polyester resin B is 6000 or less, the polyester resin B easily enters the gaps between the pigments, and the adhesion of the coating layer 210 can be improved. The number average molecular weight of the polyester resin B is more preferably 2500 or more and 5000 or less, and particularly preferably 3000 or more and 4500 or less. Further, when the hydroxyl value of the polyester resin B is 20 or more, the number of cross-linking points increases, so that the adhesion of the coating layer 210 to the undercoat layer 23 can be improved. The hydroxyl value of the polyester resin B is more preferably 30 or more, and particularly preferably 40 or more. The upper limit of the hydroxyl value of the polyester resin B is not particularly limited, but is preferably 200 or less, for example.

In the coating paint, the ratio of the mass of the polyester resin B to the mass of the polyester resin A (polyester resin B / polyester resin A) is preferably 0.25 or more and 4 or less. When this ratio is 0.25 or more, the adhesion of the coating layer 210 can be effectively improved. Further, when this ratio is 4 or less, the workability of the coating layer 210 can be effectively improved. The mass ratio of the polyester resin A to the polyester resin B is more preferably 0.4 or more and 2.5 or less, and particularly preferably 0.65 or more and 1.5 or less.

The pigment contained in the coating paint preferably contains rutile-type titanium oxide. That is, it is preferable that the coating layer 210 contains rutile-type titanium oxide. Since rutile-type titanium oxide has a higher refractive index than other pigments, the difference in refractive index between the resin and air contained in the coating layer 210 and rutile-type titanium oxide can be increased. By increasing this difference in refractive index, the diffuse reflectance of the coating layer 210 can be increased.

The rutile-type titanium oxide particles may be a single particle, or may be a rutile-type titanium oxide particle coated with silica, alumina, zirconia, zinc oxide, antimony oxide, an organic substance, or the like. Examples of organic substances used for coating include polyols such as pentaerythrit and trimethylolpropane, alkanolamines such as trietanolamines and organic acid salts of trimethylolamine, and silicones such as silicone resins and alkylchlorosilanes. Can be.

The average particle size of rutile-type titanium oxide is preferably 200 nm or more and 400 nm or less. In this case, the reflectance of the coating layer 210 can be improved, and the light that has passed through the photocatalyst layer 3 and reached the coating layer 210 can be easily reflected toward the photocatalyst layer 3. Further, light having a wavelength that easily activates the photocatalyst 30 contained in the photocatalyst layer 3 can be easily reflected by the coating layer 210. The average particle size of rutile-type titanium oxide is more preferably 250 nm or more and 350 nm or less. The average particle size of rutile-type titanium oxide is determined by observing the coating layer 210 with an electron microscope at a magnification of 10,000 times, and the rutile-type titanium oxide projected in the field of view from the smaller particle size. It is an additive average value of the particle size of the remaining rutile-type titanium oxide excluding 5% from the larger one of 20%.

In the coating layer 210, the solid content volume concentration of rutile-type titanium oxide is preferably 20% or more. In this case, the volume of the voids between the particles can be made larger than the volume of the resin even when the coating layer 210 is in the close-packed state by the particles of rutile-type titanium oxide. Since the refractive index of the voids is lower than the refractive index of the pigment and the refractive index of the resin, light is likely to be reflected at the interface between the pigment and the voids and the interface between the resin and the voids. Therefore, the diffuse reflectance of the coating layer 210 can be improved by providing sufficient voids in the coating layer 210. The solid content volume concentration of rutile-type titanium oxide is more preferably 25% or more. In this case, the diffuse reflectance of the coating layer 210 can be further improved. The solid content volume concentration of rutile-type titanium oxide is preferably 70% or less, more preferably 65% or less, and particularly preferably 40% or less. In this case, the strength of the coating layer 210 can be ensured, and the brittleness of the coating layer 210 can be suppressed.

The coating coating material may contain a component having a larger average particle size and a lower refractive index than rutile-type titanium oxide (hereinafter, also referred to as a low refractive index component). In this case, the voids in the coating layer 210 can be increased, and light can be reflected at the interface with the rutile-type titanium oxide. Therefore, the diffuse reflectance of the coating layer 210 can be effectively improved. The average particle size of the low refractive index component is preferably 1 μm or more and 10 μm or less, more preferably 3 μm or more and 8 μm or less, and more preferably 4 μm or more and 7 μm or less. The refractive index of the low refractive index component is preferably 0.5 or more lower than the refractive index of rutile-type titanium oxide, and more preferably 1 or more lower. The low refractive index component can include, for example, one or more selected from the group consisting of silica, calcium carbonate, barium sulfate, zinc oxide, and resin powders such as acrylic, polyester, and PTFE. The solid content volume concentration in the coating layer 210 of the low refractive index component is 9 to 25%, preferably 10 to 17%. In this case, the processability and corrosion resistance of the coating layer 210 can be ensured while improving the diffuse reflectance of the coating layer 210.

The ratio of voids in the coating layer 210 is preferably 0.02 times or more and 1.1 times or less, more preferably 0.3 times or more and 1.0 times or less, and 0.5 times the solid content volume material of the coating layer 210. More than 0.95 times or less is particularly preferable. In this case, the processability and adhesion of the coating layer 210 can be ensured while improving the diffuse reflectance of the coating layer 210. The size of the voids in the coating layer 210 is, for example, 200 nm or more and 400 nm or less, preferably 250 nm or more and 350 nm or less. In this case, the processability and corrosion resistance of the coating layer 210 can be ensured while improving the diffuse reflectance of the coating layer 210. However, since it is difficult to control the size of the voids in the coating layer 210, the size of the voids in the coating layer 210 unless extremely large voids are generated or the diffuse reflectance of the coating layer 210 is not particularly affected. Is not particularly limited.

The thickness of the coating layer 210 is preferably 5 μm or more and less than 100 μm. When the thickness of the coating layer 210 is less than 100 μm, it is possible to prevent the coating layer 210 from becoming brittle. From the viewpoint of appearance finish, 20 μm to 50 μm is preferable, and 25 μm to 35 μm is more preferable. In this case, the light reflectance of the coating layer 210 can be improved, the brittleness of the coating layer 210 can be suppressed, and the strength of the coating layer 210 can be ensured. The thickness of the coating layer 210 is more preferably less than 50 μm. In this case, it is possible to suppress the generation of armpits (small bulges and holes in the shape of bubbles) when the coating layer 210 is formed. The coating layer 210 is not limited to the case where it is composed of a single layer, and may be composed of a plurality of layers.

The central average roughness Ra of the interface between the coating layer 210 and the intermediate protective layer 4 is preferably 0.8 μm or more, more preferably 1.1 μm or more, and particularly preferably 1.6 μm or more. In this case, the adhesion between the coating layer 210 and the intermediate protective layer 4 can be improved, and the diffuse reflectance of the coating layer 210 can be improved. The central average roughness Ra of the interface between the coating layer 210 and the intermediate protective layer 4 is preferably 4 μm or more. In this case, the intermediate protective layer 4 and the photocatalyst layer 3 can be easily flattened, and the stain resistance of the photocatalyst layer 3 can be improved. The central average roughness Ra of the interface between the coating layer 210 and the intermediate protective layer 4 can be increased by, for example, the following method.
(A) The coating paint and the paint for forming the intermediate protective layer 4 are laminated in an undried state.
(B) The concentration of the pigment in the coating layer 210 is made higher than the concentration of the pigment in the intermediate protective layer 4.
(C) Adding a pigment having a large average particle size to the coating layer 210.
(D) To reduce the viscosity of the coating paint.
(E) To reduce the difference in surface tension between the coating paint and the paint for forming the intermediate protective layer 4.

(Second example)
The coating layer 210 of the second example is a coating film layer having low gloss, and is preferably a matte coating film layer. The coating layer 210 of the second example is a coating material containing, for example, a resin binder containing a polyester resin and a curing agent, titanium oxide, and organic polymer fine particles having an average particle diameter of 4 to 9 μm (hereinafter, also referred to as the coating material of the second example). Can be formed from.

As the polyester resin contained in the resin binder, the same components as the polyester resin contained in the undercoat layer 23 of the first embodiment can be used.

As the curing agent contained in the resin binder, the same components as the curing agent contained in the undercoat layer 23 of the first embodiment can be used, and for example, the amino resin, the blocked isocyanate compound, and the like are used. Is preferable. Further, the coating material of the second example may contain the same components as the curing catalyst contained in the undercoat layer 23 of the first embodiment in order to promote curing.

As the titanium oxide contained in the coating material of the second example, the same components as the titanium oxide contained in the undercoat layer 23 of the first embodiment can be used. The content of titanium oxide in the coating material of the second example is preferably 100 parts by mass or more and 250 parts by mass or less, and preferably 140 parts by mass or more and 190 parts by mass or less with respect to 100 parts by mass of the resin binder component. In this case, the finishability, high diffuse reflectance, and adhesion of the coating layer 210 of the second example can be improved in a well-balanced manner.

As described above, the coating material of the second example contains organic polymer fine particles having an average particle diameter of 4 to 9 μm. As a result, the coating layer 210 can be made to have low gloss and high diffuse reflectance. Examples of the organic polymer fine particles include urea resin-based organic polymer fine particles obtained by pulverizing a resin obtained by a condensation reaction between urea and an aldehyde component, acrylic resin-based organic polymer fine particles, and the like. The organic polymer fine particles may be hollow.

The average particle size of the organic polymer fine particles is 4 μm or more and 9 μm or more, and preferably 5 μm or more and 8 μm or less. In this case, the finish property of the coating layer 210 can be improved while improving the diffuse reflectance of the coating layer 210. The average particle size of the organic polymer fine particles is the median size (d50) of the volume-based particle size distribution measured by the laser diffraction / scattering method using a microtrack particle size distribution measuring device (trade name "MT3300", manufactured by Nikkiso Co., Ltd.). ) Is the value.

Commercially available products of organic polymer fine particles include Pergopack M3 (manufactured by Lonza Japan, trade name), GR-800 (manufactured by Negami Kogyo Co., Ltd., trade name), Techpolymer MBX-5, Techpolymer MBX-8 (above, Sekisui Chemical). Company-made, product name) and the like.

The content of the organic polymer fine particles in the coating material of the second example is preferably 10 parts by mass or more and 30 parts by mass or less, and more preferably 11 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the resin binder component.

The thickness of the coating layer 210 of the second example is preferably 20 μm or more and 35 μm or less, and more preferably 25 μm or more and 33 μm or less. In this case, the hiding property of the coating layer 210 can be improved, and when the coating material of the second example is applied, it is easy to apply the coating layer 210 evenly and uniformly.

The paint of the second example may contain a matting agent such as silica, a solvent, a leveling agent, a surface conditioner, an ultraviolet absorber, a light stabilizer, a pigment dispersant, an armpit inhibitor and the like, if necessary. ..

Examples of the coating method of the paint of the second example include curtain coating, roll coating, immersion coating, spray coating and the like. When the paint of the second example is pre-coated by coil coating or the like, the curtain coating method and the roll coating method are recommended because of its economic efficiency. When applying the roll coating method, a top feed or bottom feed method using three rolls is recommended in order to maximize the uniformity of the coated surface, but in practice, a normal bottom feed method using two rolls ( So-called natural reverse coating, natural coating) may be used.

The curing condition (baking condition) of the coating material of the second example is, for example, performed at a material reaching maximum temperature of 160 to 260 ° C. in the range of 15 to 90 seconds.

On the surface of the base material 2 to which the coating layer 210 of the second example is applied, the 60-degree mirror glossiness is preferably in the range of 5 to 20%, preferably 6 to 15%. In this case, it is easy to obtain highly diffuse reflected light. Further, according to the coating layer 210 of the second example, the diffuse reflectance at a wavelength of 555 nm of light can be achieved to be 85% or more, preferably 88% or more.

2-2-2. Photocatalytic action The photocatalytic action expressed by the coating material 1 according to the second embodiment will be described with reference to FIG.

Similar to the coating material 1 according to the first embodiment, the coating material 1 of the present embodiment is directly irradiated to the photocatalyst layer 3 because the light reflectance of the coating layer 210 at a wavelength of 555 nm is 85% or more. Not only the light but also the light that has passed through the photocatalyst layer 3 and is reflected by the coating layer 210 can reach the photocatalyst 30. Therefore, light can be efficiently reached to the photocatalyst 30, and the photocatalytic action of the photocatalyst 30 can be efficiently exhibited.

Further, in the coating material 1 of the present embodiment, since the diffuse reflectance of light having a wavelength of 555 nm of the coating layer 210 is 85% or more, the light that has passed through the photocatalyst layer 3 and reached the coating layer 210 is transferred to the photocatalyst layer 3 It can be diffused over a wide area toward (see FIG. 4). Therefore, the light can reach the photocatalyst 30 particularly efficiently, and the photocatalytic action of the photocatalyst 30 can be exhibited particularly efficiently. As a result, a particularly high photocatalytic action can be exhibited from the initial stage of irradiating the photocatalytic layer 3 with light, and this photocatalytic action can be maintained for a particularly long period of time.

Of course, the photocatalytic action expressed by the coating material 1 of the present embodiment also includes a hydrophilic action, an antifouling action, an inactivating action of bacteria or a virus, and the like. In the coating material 1 of the present embodiment, the inactivating action of bacteria or viruses can be exhibited particularly efficiently even at the initial stage of irradiating the photocatalyst layer 3 with light, and this inactivating action is maintained for a long period of time. it can.

3. 3. Method of Inactivating Bacteria or Virus As described above, the bacteria or virus can be inactivated by using the coating material 1 of the first embodiment and the second embodiment.

Therefore, in the method of inactivating a bacterium or a virus, the photocatalyst 30 is activated by irradiating the photocatalyst layer 3 of the above-mentioned coating material 1 with light to inactivate the bacterium or the virus. More specifically, by irradiating the photocatalyst layer 3 with light from a light source such as sunlight, a fluorescent lamp, or an LED lamp, the photocatalyst 30 is in an excited state, and active oxygen having a strong oxidizing power on the surface of the photocatalyst layer 3 Occurs. The active oxygen decomposes bacteria, viruses, etc., so that the bacteria or viruses are inactivated. Moreover, since active oxygen can decompose organic substances, it can also exhibit an antifouling effect.

Bacteria and viruses that can be inactivated by the photocatalytic action of the coating material 1 include blue mold (penicillium pinohirum), fusalium, Staphylococcus aureus, influenza A virus, cat casirivirus, norovirus, Bacillus anyabhattai, Aeromiclobium sp, Marmorico sp, Bacillus sp and the like are included. Of course, the bacteria / viruses that can be inactivated by the photocatalytic action of the coating material 1 include bacteria / viruses other than the above.

The coating material 1 exhibits an inactivating action of bacteria or viruses from the initial stage when the photocatalyst layer 3 is irradiated with light. For example, the following indexes can be considered as indexes for exhibiting the inactivating action of bacteria or viruses from the initial stage of irradiating the photocatalyst layer 3 with light.

As described above, the inactivating action of the bacterium or virus is exerted by the active oxygen generated on the surface of the photocatalyst layer 3. Since this active oxygen can decompose not only bacteria or viruses but also organic substances such as methylene blue, the resolution of methylene blue can be used as an index of the inactivating action of bacteria or viruses. Therefore, if the resolution of methylene blue is high in the initial stage of irradiating the photocatalyst layer 3 with light, it can be considered that the inactivating action of the bacterium or virus is exhibited from the initial stage of irradiating the photocatalyst layer 3 with light. ..

The resolution of methylene blue can be measured, for example, by the following method. First, a dry coating film containing methylene blue at an arbitrary concentration and having an arbitrary thickness is provided on the photocatalyst layer 3. Next, the photocatalyst layer 3 is irradiated with a UV lamp at an arbitrary illuminance and at an arbitrary time. When methylene blue is decomposed by the photocatalytic effect, the color of the dry coating film changes. Therefore, the resolution of methylene blue can be measured based on the color difference ΔE of the dry coating film before and after irradiation with the UV lamp. The method for measuring the color difference ΔE is not particularly limited, but it can be measured using, for example, a spectrophotometric system (product number CM-3700d) manufactured by Konica Minolta Co., Ltd.

In the coating material 1 of the first embodiment and the second embodiment, a 100-fold diluted methylene blue dry coating film (adhesion amount 44.4 mg / m ² ) is provided on the photocatalyst layer 3 and 10.0 ± 0. When ultraviolet rays are irradiated for 1 hour at an irradiation intensity of 5 W / m ² , the percentage of the color difference (ΔE) of the dry coating film after irradiation to the color difference (ΔE ₀ ) of the dry coating film before irradiation is 30% or more. Is preferable.

In particular, in the coating material 1 of the second embodiment, a 100-fold diluted methylene blue dry coating film (adhesion amount 44.4 mg / m ² ) is provided on the photocatalyst layer 3 and ultraviolet rays are applied at 10.0 ± 0.5 W. When irradiated at an illuminance of / m ² for 1 hour, the percentage of the color difference (ΔE) of the dry coating film after ultraviolet irradiation to the color difference (ΔE ₀ ) of the dry coating film before ultraviolet irradiation is preferably 40% or more. ..

Further, in the coating material 1 of the first embodiment and the second embodiment, a dry coating film of methylene blue having an adhesion amount of 44.4 mg / m ² is provided on the photocatalyst layer 3 to obtain 0.0 ± 0.5 W / m ² . When ultraviolet rays are irradiated for 11 hours at the irradiation intensity, the percentage of the color difference (ΔE) of the dry coating film after irradiation to the color difference (ΔE ₀ ) of the dry coating film before irradiation increases by 6% or more per hour. Is preferable.

Further, in the coating material 1 of the first embodiment and the second embodiment, a dry coating film of methylene blue having an adhesion amount of 44.4 mg / m ² is provided on the photocatalyst layer 3 to obtain 0.0 ± 0.5 W / m ² . When ultraviolet rays are irradiated for 11 hours at the irradiation intensity, the ratio of the color difference (ΔE) of the dry coating film after irradiation to the color difference (ΔE ₀ ) of the dry coating film before irradiation is preferably 60% or more. More preferably, it is 70% or more.

Hereinafter, the present invention will be specifically described with reference to Examples.

(Examples 1 and 2 and Comparative Examples 1 and 2)
First, a 55% AL-Zn hot-dip galvanized steel sheet was prepared as a base material.

Next, the undercoat paint shown in Table 1 below was applied onto the surface of the base material to form a coating film, and then the undercoat layer 23 was formed by heating at 220 ° C. for about 1 minute. The amount of the undercoat paint applied was 12.5 μm in terms of dry film thickness.

Next, the coating paint shown in Table 1 below was applied onto the undercoat layer 23 to form a coating film, and then the coating layer was formed by heating at 220 ° C. for about 1 minute. The amount of the coating paint applied was 27.5 μm in terms of dry film thickness. The reflectance and diffuse reflectance of light having a wavelength of 555 nm on the surface of the coating layer were the values shown in Table 1 below. The reflectance and diffuse reflectance of the coating layer were measured using a spectrocolorimeter (CM-3700d) manufactured by Konica Minolta.

Next, the protective layer coating material shown in Table 1 below was applied onto the undercoat layer 23 to form a coating film, and then heated at 200 ° C. for about 1 minute to form an intermediate protective layer. The coating amount of the protective layer paint was 1.0 μm in terms of dry film thickness.

Next, the photocatalyst coating material shown in Table 1 below was applied onto the intermediate protective layer to form a coating film, and then heated at 220 ° C. for about 1 minute to form a photocatalyst layer. The amount of the photocatalytic paint applied was 1.0 μm in terms of dry film thickness. A coating material was produced by the above steps.

The details of the paints shown in Table 1 below are as follows.
-KPP-76: Playmer paint (product number KPP-76) manufactured by Kansai Paint Co., Ltd. Includes a resin binder and a titanium oxide pigment.
-KP-217: White paint manufactured by Kansai Paint Co., Ltd. (product number KP-217).
-KP-217 + organic polymer fine particles: A mixture of white paint (product number KP-217) manufactured by Kansai Paint Co., Ltd. and acrylic resin beads (particle size 5 μm), adjusted so that the glossiness after application and drying is 10. Painted.
-MX-110F: White paint manufactured by AkzoNobel Coating Co., Ltd. (product number MX-110F).
-VCT-02BSLB: Protective paint manufactured by Toyotsu Vehitec Co., Ltd. It contains a raw material component containing an alkoxysilane and a substance having photocatalytic activity.
-VCTIII-02BSLC: Protective paint manufactured by Toyotsu Vehitec Co., Ltd. It contains a raw material component containing an alkoxysilane and a substance having photocatalytic activity in the visible light region.

(Evaluation)
1. 1. Resolution of Methylene Blue The coating materials of Examples 1 and 2 and Comparative Examples 1 and 2 were irradiated with sunlight for 6 hours to remove the coating material of Comparative Example 2 containing no photocatalytic layer, and Examples 1 and 2 and Comparative Example 1 The photocatalyst layer of No. 1 was excited. Next, methylene blue diluted 100-fold with pure water was applied onto the surface of each coating material and dried to form a dry coating film of methylene blue having an adhesion amount of 44.4 mg / m ² . Next, each coating material was irradiated with ultraviolet rays. The irradiation intensity of ultraviolet rays was 10.0 ± 0.5 W / m ² . After starting the irradiation with ultraviolet rays, the color difference of each coating material was measured at regular intervals, and the percentage with respect to the initial color difference ΔE0 was determined. The results are shown in Table 2 and FIG. 5 below.

According to Table 2 and FIG. 5, the coating material of Comparative Example 1 has a larger percentage of the color difference ΔE than the coating material of Comparative Example 2. It is considered that this is because the coating material of Comparative Example 2 does not have a photocatalytic layer and does not easily decompose methylene blue. Further, the coating materials of Examples 1 and 2 have a larger percentage of the color difference ΔE than the coating materials of Comparative Example 1, and in particular, the percentage of ΔE is larger from the initial stage of irradiation with ultraviolet rays. It is considered that this is because the coating materials of Examples 1 and 2 have a coating layer having high reflectance in addition to the photocatalytic layer, so that the photocatalytic effect can be efficiently exhibited from the initial stage of ultraviolet irradiation. Further, the coating material of Example 1 has a larger percentage of the color difference ΔE than the coating material of Example 2 after 11 hours and 21 hours of irradiation with ultraviolet rays. It is considered that this is because the coating layer of Example 1 has a higher diffuse reflectance than the coating layer of Example 2, and the photocatalytic effect can be exhibited particularly efficiently.

2. Inactivating action of fungi, molds and viruses The inactivating action of fungi, molds and viruses was measured with respect to the coating material of Example 1 in which the resolution of methylene blue was particularly excellent and Comparative Example 1 in which the resolution of methylene blue was lower than that of Example 1. did. Further, in Comparative Example 2 which does not have the resolution of methylene blue due to the absence of the photocolor catalyst layer, the inactivating action of some fungi, molds and viruses was measured. The results are shown below.

(A) Molds and fungi The fungi and molds shown in Table 3 below were placed on the surface of the coating materials of Example 1 and Comparative Examples 1 and 2. Next, using a fluorescent lamp having an illuminance of 1000 lp, each coating material was irradiated with the light of the fluorescent lamp through a UV cut filter for 24 hours. Then, the reduction rate was calculated from the viable cell count before light irradiation and the viable cell count after irradiation. The results are shown in Table 3 below.

According to Table 3, the dressing of Comparative Example 1 has a larger reduction rate of the viable cell count than the dressing of Comparative Example 2. It is considered that this is because the coating material of Comparative Example 1 has a photocatalytic layer, so that the number of molds or fungi can be reduced by the photocatalytic effect. Further, the dressing of Example 1 has a larger reduction rate of the viable cell count than the dressing of Comparative Examples 1 and 2. This is because the coating material of Example 1 has a coating layer having high reflectance and diffuse reflectance in addition to the photocatalytic layer, so that the photocatalytic effect can be efficiently exhibited from the initial stage of ultraviolet irradiation, and this photocatalytic effect can be exhibited for a long period of time. It is thought that it can be maintained.

(B) Influenza A virus An influenza A virus was placed on the surface of the coating materials of Example 1 and Comparative Examples 1 and 2. Next, using a fluorescent lamp having an illuminance of 3000 lp, each coating material was irradiated with the light of the fluorescent lamp through a UV cut filter for 8 hours. Then, the ratio of the number of live viruses 4 hours after the start of irradiation to the number of live viruses 8 hours after the start of irradiation was calculated with respect to the number of live viruses before irradiation. The results are shown in Table 4 below.

According to Table 4, the dressing of Comparative Example 1 has a smaller ratio of the number of live viruses than the dressing of Comparative Example 2. It is considered that this is because the coating material of Comparative Example 1 has a photocatalytic layer, and the number of viruses can be reduced by the photocatalytic effect thereof. Further, the dressing of Example 1 has a smaller ratio of the number of live viruses than the dressing of Comparative Examples 1 and 2. This is because the coating material of Example 1 has a coating layer having high reflectance and diffuse reflectance in addition to the photocatalytic layer, so that the photocatalytic effect is efficiently exhibited from the initial stage of ultraviolet irradiation, and this photocatalytic action is long. It is thought that this is because it is maintained for a period of time.

(C) Nekokasirivirus A catkasirivirus was placed on the surface of the coating materials of Example 1 and Comparative Examples 1 and 2. Next, using a fluorescent lamp having an illuminance of 3000 lp, each coating material was irradiated with the light of the fluorescent lamp through a UV cut filter for 8 hours. Then, the ratio of the number of live viruses 8 hours after the start of irradiation to the number of live viruses before light irradiation was calculated. The results are shown in Table 5 below.

According to Table 5, the dressing of Comparative Example 1 has a smaller ratio of the number of live viruses than the dressing of Comparative Example 2. It is considered that this is because the coating material of Comparative Example 1 has a photocatalytic layer, and the number of viruses can be reduced by the photocatalytic effect thereof. Further, the dressing of Example 1 has a smaller ratio of the number of live viruses than the dressing of Comparative Examples 1 and 2. This is because the coating material of Example 1 has a coating layer having high reflectance and diffuse reflectance in addition to the photocatalytic layer, so that the photocatalytic effect is efficiently exhibited from the initial stage of ultraviolet irradiation, and the photocatalytic effect is long. It is thought that this is because it is maintained for a period of time.

(D) Bacteria collected from soil Four types of bacteria (Bacillus anyabattai, Aeromiclobium sp, Marmorico sp, Bacillus sp) collected from soil were placed on the surface of the dressing of Example 1 and Comparative Example 1. Next, using a fluorescent lamp having an illuminance of 1000 lp, each coating material was irradiated with the light of the fluorescent lamp through a UV cut filter for 16 hours. Then, the reduction rate was calculated from the viable cell count before light irradiation and the viable cell count after irradiation. The results are shown in Table 6 below.

According to Table 6, the dressing of Example 1 has a large reduction rate of the viable cell counts, and particularly a large reduction rate of the viable cell counts of Aeromiclobium sp, Marmorico sp, and Bacillus sp. It is considered that this is because the coating material of Example 1 has high reflectance and diffuse reflectance, so that the photocatalytic effect is efficiently exhibited from the initial stage of ultraviolet irradiation, and the photocatalytic effect is maintained for a long period of time.

1 Coating material 2 Base material 21 Coating layer 22 Plated steel sheet 3 Photocatalyst layer 4 Intermediate protective layer

Claims (9)

A base material in which at least a part of the surface is composed of a coating layer having a reflectance of light having a wavelength of 555 nm of 85% or more, and
The photocatalyst layer located on the coating layer and
including,
Covering material. The photocatalytic layer contains anatase-type titanium oxide.
The covering material according to claim 1. The coating layer contains rutile-type titanium oxide.
The covering material according to claim 1 or 2. Includes an intermediate protective layer provided between the coating layer and the photocatalyst layer.
The covering material according to any one of claims 1 to 3. The base material includes a plated steel sheet and the coating layer provided on the plated steel sheet.
The covering material according to any one of claims 1 to 4. A dry coating film of methylene blue having an adhesion amount of 44.4 mg / m ² is provided on the photocatalyst layer, and the dry coating film is irradiated with ultraviolet rays at an irradiation intensity of 10.0 ± 0.5 W / m ² for 11 hours. In this case, the ratio of the percentage of the color difference (ΔE) of the dry coating film after the irradiation of the ultraviolet rays to the color difference (ΔE ₀ ) of the dry coating film before the irradiation of the ultraviolet rays increases by 6% or more on average per hour. The coating material according to any one of claims 1 to 5. A dry coating film of methylene blue having an adhesion amount of 44.4 mg / m ² is provided on the photocatalyst layer, and the dry coating film is irradiated with ultraviolet rays at an irradiation intensity of 10.0 ± 0.5 W / m ² for 1 hour. In this case, the percentage of the color difference (ΔE) of the dry coating film after irradiation with the ultraviolet rays for 1 hour is 30% or more with respect to the color difference (ΔE ₀ ) of the dry coating film before the irradiation with the ultraviolet rays.
The covering material according to any one of claims 1 to 6. A dry coating film of methylene blue having an adhesion amount of 44.4 mg / m ² is provided on the photocatalyst layer, and the dry coating film is irradiated with ultraviolet rays at an irradiation intensity of 10.0 ± 0.5 W / m ² for 11 hours. In this case, the percentage of the color difference (ΔE) of the dry coating film after irradiation with the ultraviolet rays for 11 hours is 60% or more with respect to the color difference (ΔE ₀ ) of the dry coating film before the irradiation with the ultraviolet rays.
The covering material according to any one of claims 1 to 7. By irradiating the photocatalyst layer of the coating material according to any one of claims 1 to 8 with light, the photocatalyst is activated and bacteria or viruses are inactivated.
A method of inactivating bacteria or viruses.

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