ANTIBACTERIAL-COATED PRODUCT, ANTIBACTERIAL COATING MATERIAL, METHOD FOR MANUFACTURING ANTIBACTERIAL COATING MATERIAL, AND METHOD FOR MANUFACTURING ANTIBACTERIAL-COATED PRODUCT

Abstract

An antibacterial coated product includes, on a base material, a coating film of an antibacterial coating material that contains at least composite ceramic powders containing a photocatalytic component, adsorbent component, and metal component, and a binder, wherein the antibacterial activity (JIS Z 2801:2010) of the coating film is 2.0 or higher and the requirement(s) of (1) and/or (2) below is/are satisfied: (1) with respect to the composite ceramic powder in the antibacterial coating material, the volume average dispersed particle diameter (D.sub.50) is 250 nm or smaller, and the ratio of the 90% cumulative volume particle diameter (D.sub.90) and the volume average dispersed particle diameter (D.sub.50), or D.sub.90/D.sub.50, is 1.5 or lower; and (2) the thickness of the coating film is 80 μm or smaller and the haze (JIS K 7136:2000) of the antibacterial coated product or coating film is 25 or lower.

Claims

1. An antibacterial coated product having, on a base material, a coating film of an antibacterial coating material that contains at least a composite ceramic powder containing a photocatalytic component, adsorbent component, and metal component, and a binder, wherein an antibacterial activity (according to JIS Z 2801:2010) of the coating film is 2.0 or higher, and requirement(s) of (1) and/or (2) below is/are satisfied: (1) with respect to the composite ceramic powder in the antibacterial coating material, a volume average dispersed particle diameter (D.sub.50) is 250 nm or smaller, and a ratio of a 90% cumulative volume particle diameter (D.sub.90) and the volume average dispersed particle diameter (D.sub.50), or D.sub.90/D.sub.50, is 1.5 or lower; and (2) a thickness of the coating film is 80 μm or smaller and a haze (according to JIS K 7136: 2000) of the antibacterial coated product or coating film is 25 or lower.

2. An antibacterial coating material that contains at least a composite ceramic powder containing a photocatalytic component, adsorbent component, and metal component, and a binder, wherein: a volume average dispersed particle diameter (D.sub.50) of the composite ceramic powder in the antibacterial coating material is 250 nm or smaller, and a ratio of a 90% cumulative volume particle diameter (D.sub.90) and the volume average dispersed particle diameter (D.sub.50), or D.sub.90/D.sub.50, of the composite ceramic powder, is 1.5 or lower; and an antibacterial activity (according to JIS Z 2801:2010) of the coating film is 2.0 or higher.

3. A method for manufacturing an antibacterial coating material whose coating film has an antibacterial activity (according to JIS Z 2801:2010) of 2.0 or higher, which includes a step to mix, using a dispersing machine, constitutive components of the antibacterial coating material including at least composite ceramic powder containing a photocatalytic component, adsorbent component, and metal component, and a binder, wherein: a volume average dispersed particle diameter (D.sub.50) of the composite ceramic powder in the antibacterial coating material is set to 250 nm or smaller, and a ratio of a 90% cumulative volume particle diameter (D.sub.90) and the volume average dispersed particle diameter (D.sub.50), or D.sub.90/D.sub.50, of the composite ceramic powder, is set to 1.5 or lower.

4. A method for manufacturing an antibacterial coated product whose coating film has an antibacterial activity (according to JIS Z 2801:2010) of 2.0 or higher, produced by applying on a base material a coating material that contains the antibacterial coating material according to claim 2.

Description

EXAMPLES

[0126] The present invention is explained in greater detail below by citing examples; however, the present invention is not limited to these examples. It should be noted that, in the examples and comparative examples, the properties, etc., of the antibacterial coating materials and properties, etc., of the coating films were measured/evaluated using the methods described below.

(Grain Diameters)

[0127] The volume average dispersed particle diameter (D.sub.50) and 90% cumulative volume particle diameter (D.sub.90), of the composite ceramic powder in each antibacterial coating material, were measured using a dynamic light-scattering particle diameter distribution measuring apparatus (LB-550 manufactured by Horiba, Ltd.).

(Storage Stability)

[0128] Each antibacterial coating material was let stand for one week at 25° C. and then visually observed and evaluated according to the criteria below:

[0129] ◯: There is no sediment.

[0130] x: Sediment has settled.

(Appearance of Coating Films)

[0131] Appearance of coating films was visually observed and evaluated according to the criteria below:

[0132] ◯: Colorless and transparent, and free of unacceptable turbidity

[0133] ◯blue: Colored slightly blue, but free of unacceptable turbidity

[0134] x: Cloudy

[0135] <Preparation of Antibacterial Coating Materials>

Example 1

[0136] 2.85 mass % of a composite ceramic powder containing photocatalytic titanium dioxide, hydroxyapatite, and silver combined into a composite, 14.29 mass % of a binder containing hydroxyl group-containing acrylic resin (acrylic polyol), and polyisocyanate curing agent, and a sufficient quantity of ethyl acetate (solvent) to bring the total to 100 mass % (to account for the remainder), were compounded and dispersed in a bead mill to prepare an antibacterial coating material.

Examples 2, 3

[0137] Antibacterial coating materials were prepared in the same manner as described in Example 1, except that the operating conditions of the bead mill were changed when the respective components were dispersed using the bead mill.

Comparative Example 1

[0138] 5.70 mass % of a composite ceramic powder containing photocatalytic titanium dioxide, hydroxyapatite, and silver combined into a composite, 14.29 mass % of a binder containing hydroxyl group-containing acrylic resin (acrylic polyol) and polyisocyanate curing agent, and a sufficient quantity of ethyl acetate (solvent) to bring the total to 100 mass % (to account for the remainder), were compounded and dispersed in a bead mill to prepare an antibacterial coating material.

Comparative Example 2

[0139] A commercially available photocatalytic indoor coating material “Lumititan NAG” (product name manufactured by Sasamic Co., Ltd.; coating material in Patent Literature 1 (Japanese Patent No. 5207744)), which contains nano-silver-supporting apatite-coated titanium dioxide, was used as an antibacterial coating material. It should be noted that, since substantial sediment was found in the container of Lumititan NAG, the content was mixed under agitation by shaking the container, and used without dilution as a coating material.

<Evaluation of Antibacterial Coating Materials>

[0140] The antibacterial coating materials in Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated for storage stability. Also, the antibacterial coating materials in Examples 1 to 3, which were found colorless and transparent or faint-colored and transparent by visual evaluation, were measured for volume average dispersed particle diameter (D.sub.50), 90% cumulative volume particle diameter (D.sub.90), and ratio of 90% cumulative volume particle diameter (D.sub.90), and volume average dispersed particle diameter (D.sub.90/D.sub.50). It should be noted that measurement using a dynamic light-scattering particle diameter distribution measuring apparatus was not performed on the antibacterial coating materials in Comparative Examples 1 and 2, because the coating materials were found cloudy by visual evaluation and the volume average grain diameters of the composite ceramic powders were clearly over 250 nm. These results are shown in Table 1.

TABLE-US-00001 TABLE 1 Antibacterial coating material Comparative Examples Examples Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Volume average 65 139 208 >250 >250 dispersed particle diameter (D.sub.50) 90% Cumulative 76 149 218 — — volume particle diameter (D.sub.90) D.sub.90/D.sub.50 1.17 1.07 1.04 — — Storage stability ◯ ◯ ◯ ◯ X Appearance of ◯ ◯ blue ◯ blue X X coating film

<Optical Evaluation of Antibacterial Coated Products>

(Preparation of Antibacterial Coated Products)

[0141] The antibacterial coating materials in Examples 1 and 2 and Comparative Examples 1 and 2 were air-sprayed on clear ABS resin sheets to prepare antibacterial coated products having coating films of the dry film thicknesses shown in Table 2.

(Optical Evaluation of Antibacterial coated Products)

[0142] Appearance of coating film was visually evaluated. Also, haze of coating film was measured with a haze meter (HZ-V3, manufactured by Suga Test Instruments Co., Ltd.). These results are shown in Table 2.

TABLE-US-00002 TABLE 2 Antibacterial coating material Comparative Examples Examples Comparative Comparative Example 1 Example 2 Example 1 Example 2 Volume average 65 139 >250 >250 dispersed particle diameter Storage stability ◯ ◯ ◯ X Film thickness 15 17 22 7 Haze 6.98 19.16 37.53 91.72 Appearance of ◯ ◯ blue X X coating film

<Antibacterial Activity Evaluation of Antibacterial Coated Products>

(Preparation of Antibacterial Coated Products)

[0143] The antibacterial coating materials in Examples 1 to 3 were air-sprayed on clear ABS sheets to prepare antibacterial coated products.

(Evaluation of Antibacterial Activity Against Staphylococcus Aureus in Antibacterial Coated Products)

[0144] This evaluation was conducted according to the film adhesion method based on JIS Z 2801:2010, “Antibacterial Products—Test for Antibacterial Activity and Efficacy,” using specimen samples (50×50 mm) representing the antibacterial coated products obtained from the antibacterial coating materials in Examples 1 to 3, culture medium (1/500 NB culture medium), and Staphylococcus aureus (NBRC 12732). The specimen sample size was three.

[0145] In the test, 0.4 mL of test bacterial fluid was inoculated on each specimen sample and then a cover film was placed on top, after which the specimen sample was kept stationary at 35±1° C. and relative humidity of 90% or above to obtain the logarithmic value of viable bacteria count and equivalent value of viable bacteria count immediately after the inoculation as well as 0.5 hours, 1 hour, 2 hours, 4 hours, 6 hours and 24 hours later. The logarithmic value of viable bacteria count and equivalent value of viable bacteria count were also obtained for an untreated test piece (control) containing no antibacterial agent and having no antibacterial property.

[0146] Using these results, the antibacterial activity was obtained (antibacterial activity “R=Ut−At” as the value remaining after subtracting the logarithmic value of viable bacteria count in the specimen sample taken 24 hours later (At) from the logarithmic value of viable bacteria count taken 24 hours later in the untreated test sample containing no antibacterial agent and having no antibacterial property (Ut). The results are shown in Table 3.

TABLE-US-00003 TABLE 3 Antibacterial coating material Example 1 Example 2 Example 3 Control Immediately Logarithmic value of 4.36 4.40 4.31 4.41 after viable bacterial count inoculation Equivalent value of viable 23,125 25,000 20,625 25,417 bacterial count 0.5 hours later Logarithmic value of 3.86 3.96 3.91 4.27 viable bacterial count Equivalent value of viable 7,292 9,167 8,125 18,750 bacterial count 1 hour later Logarithmic value of 4.10 4.22 4.10 4.21 viable bacterial count Equivalent value of viable 12,708 16,458 12,708 16,250 bacterial count 2 hours later Logarithmic value of 1.92 2.02 2.09 4.18 viable bacterial count Equivalent value of viable 83 104 123 15,000 bacterial count 4 hours later Logarithmic value of 0.77 0.60 0.02 4.42 viable bacterial count Equivalent value of viable 6 4 1 26,458 bacterial count 6 hours later Logarithmic value of 1.09 0.96 0.61 4.25 viable bacterial count Equivalent value of viable 12 9 4 17,917 bacterial count 24 hours later Logarithmic value of <−0.20 <−0.20 <−0.20 4.77 viable bacterial count Equivalent value of viable <1 <1 <1 58,750 bacterial count Antibacterial activity >4.97 >4.97 >4.97 —
(Evaluation of Antibacterial Activity Against Escherichia Coli in Antibacterial coated Products)

[0147] This evaluation was conducted according to the film adhesion method based on JIS Z 2801:2010, “Antibacterial Products—Test for Antibacterial Activity and Efficacy,” using specimen samples (50×50 mm) representing the antibacterial coated products obtained from the antibacterial coating materials in Examples 1 and 2, culture medium (1/500 NB culture medium), and Escherichia coli (NBRC 3972). The specimen sample size was three.

[0148] In the test, 0.4 mL of test bacterial fluid was inoculated on each specimen sample and then a cover film was placed on top, after which the specimen sample was kept stationary for 24 hours at 35±1° C. and relative humidity of 90% or above, followed by measurement of viable bacteria count. The antibacterial activity R=Ut−At was obtained by measuring the logarithmic value of viable bacteria count taken 24 hours later in the untreated test piece (control) containing no antibacterial agent and having no antibacterial property (Ut), and the logarithmic value of viable bacteria count taken 24 hours later in the specimen sample (At). The results are shown in Table 4.

TABLE-US-00004 TABLE 4 Antibacterial coating material Example 1 Example 2 Control Immediately Logarithmic value of viable 5.08 5.08 5.08 after bacterial count inoculation Viable bacterial count 120,000 120,000 120,000 24 hours later Logarithmic value of viable <1 <1 7.11 bacterial count Viable bacterial count <10 <10 13,000,000 Antibacterial activity >6.11 >6.11 —

[0149] As shown in Table 1 to Table 4, antibacterial coated products having an antibacterial activity of 2.0 or higher—a level required by many medical institutions—as well as highly transparent coating films with excellent appearance, can be obtained easily according to the present invention, which makes the utility value of the present invention extremely high.