WO2008050625A1

WO2008050625A1 - Antibacterial ceramic product, ceramic surface treatment agent, and method for production of antibacterial ceramic product

Info

Publication number: WO2008050625A1
Application number: PCT/JP2007/070076
Authority: WO
Inventors: Kohei Shimoda; Issei Okada; Kenji Miyazaki
Original assignee: Sumitomo Electric Industries, Ltd.
Priority date: 2006-10-27
Filing date: 2007-10-15
Publication date: 2008-05-02
Also published as: JP5358877B2; CN101360696A; JP2008105920A

Abstract

Disclosed is a novel antibacterial ceramic product which has a high antibacterial metal use efficiency and therefore can provide a satisfactory antibacterial property even when the antibacterial metal is used in a reduced amount compared to a conventional one. Also disclosed is a ceramic surface treatment agent which can be used for the production of the antibacterial ceramic product. Further disclosed is a method for producing an antibacterial ceramic product by using the ceramic surface treatment agent. The antibacterial ceramic product has, on its surface, a metal nanoparticle which comprises at least silver and has an average particle diameter of 200 nm or less. The ceramic surface treatment agent comprises a metal nanoparticle dispersed in a dispersion medium in a colloidal form, wherein the metal nanoparticle has a 90% accumulated diameter (D90) in the particle size distribution of 150 nm or less. The method for producing the an antibacterial ceramic product comprises the steps of applying the ceramic surface treatment agent onto the surface of a ceramic product and firing the ceramic product at 800 to 1600˚C.

Description

Specification

Antibacterial ceramic products, ceramic surface treatment agents, and methods of manufacturing antibacterial ceramic products

[0001] The present invention relates to an antibacterial ceramic product provided with antibacterial properties on the surface of ceramic products represented by ceramic products such as sanitary ware and Japanese and Western tableware, and a ceramic industry used for manufacturing the antibacterial ceramic products. The present invention relates to a surface treatment agent and a method for producing an antibacterial ceramic product using the ceramic surface treatment agent.

Background art

[0002] Antibacterial agents for imparting antibacterial properties to the surface of ceramic products include metals such as silver, copper, tin and zinc (hereinafter, these metals may be collectively referred to as "antibacterial metals") Is used. These antibacterial metals function as a catalyst, change oxygen dissolved in water to active oxygen, and suppress the growth of fungi and fungi by the action of the changed active oxygen. It is known that antibacterial properties are exhibited by the so-called oligodynamic effect. When antibacterial properties are imparted to the surface of ceramic products using the antibacterial metal, the substrate of ceramic products is considered in consideration of maintaining good antibacterial properties for as long as possible. In general, an antibacterial metal is contained in the glaze layer formed on the surface of the unglazed product or the like, or in the substrate itself.

[0003] For example, in Patent Document 1, in order to prevent the antibacterial metal from being eroded by the melt of the glaze component during firing, the antibacterial metal is supported on hydroxyapatite to form composite particles. After forming and adding the composite particles to the glaze, the glaze is applied to the surface of the substrate and baked to form a glaze layer containing an antibacterial metal. Further, in Patent Document 2, for the same purpose, an antibacterial metal ion is contained in a calcium phosphate compound to form composite particles, and after adding the composite particles to the glaze, the glaze is added to the surface of the substrate. It is described that a glaze layer containing an antibacterial metal is formed by applying and baking.

[0004] Also, in Patent Document 3, an inorganic pigment as composite particles retaining an antibacterial metal is added to a glaze, and the glaze is applied to the surface of the substrate and then baked to obtain an antibacterial agent. Contains metallic A glaze layer is formed, or the inorganic pigment is added to the clay or magnetic earth that is the basis of the ceramic product base. After the ceramic clay is molded into the shape of the ceramic product, it is baked and applied to the base itself. It describes that an antibacterial metal is contained. Further, in Patent Document 4, silver oxide, metallic silver, or an arbitrary silver compound is added to the lower paint, and the surface of the ceramic product base or the glaze layer formed on the surface is added using the lower paint. Antibacterial by drawing a sketch on the surface, adding silver oxide or the like to the glaze, and applying the glaze to the surface of the substrate or the glaze layer formed on the surface and baking. It describes the formation of a rough sketch or glaze layer containing a functional metal!

Patent Document 1: JP-A-5-201747 (Claim 1, Paragraph [0007], Paragraph [0010]) Patent Document 2: JP-A-6-127975 (Claim 1, Paragraphs [0008] to [0009] Patent Document 3: Japanese Patent Laid-Open No. 7-233334 (Claims 1, 2, Paragraph [0009], Paragraph [0025]) Patent Document 4: Japanese Patent Laid-Open No. 7-196384 (Claims;! To 8, Paragraph [ 0014])

Disclosure of the invention

Problems to be solved by the invention

[0005] However, since all of the above conventional ceramic products have low utilization efficiency of antibacterial metals, sufficient antibacterial properties corresponding to the amount of antibacterial metals used cannot be obtained, and in order to obtain high antibacterial properties. Because the amount of antibacterial metal used must be increased, for example, the glaze layer or background may not have a predetermined color (often darker than the predetermined color), If it leads to cost increase, it may cause a problem.

[0006] An object of the present invention is to provide a novel antibacterial ceramic industry that can obtain sufficient antibacterial properties even when the amount of the antibacterial metal used is less than the current amount because the use efficiency of the antibacterial metal is high. An object of the present invention is to provide a product, a ceramic surface treatment agent that can be used for producing the antibacterial ceramic product, and a method for producing an antibacterial ceramic product using the ceramic surface treatment agent. Means for solving the problem

[0007] The antibacterial property of the antibacterial metal based on the oligodynamic effect described above is the antibacterial exposed on the surface of the glaze layer in the case of a ceramic product to be manufactured, for example, a ceramic product having a glaze layer The contact area between the conductive metal and water increases, and the contact area tends to increase as the particle size of the antibacterial metal decreases and the specific surface area increases. By the way According to the inventor's investigation, all of the conventional ceramic products have a large particle size of the antibacterial metal exposed on the surface and a small specific surface area, so the utilization efficiency of the antibacterial metal is low. Not enough antibacterial properties to meet the amount of antibacterial metal used.

Yes

[0008] Therefore, as a result of examining the range of the particle diameter of the antibacterial metal exposed on the surface of the ceramic product in order to increase the utilization efficiency of the antibacterial metal, the inventor has It was found that metal nanoparticles with an average particle diameter of 200 nm or less should be present on the surface of ceramic products. Therefore, the invention according to claim 1 is an antibacterial ceramic product characterized in that metal nanoparticles containing at least silver and having an average particle diameter of 200 nm or less are present on the surface!

[0009] Further, the inventor exposes as many metal nanoparticles having an average particle diameter of 200 nm or less as described above to the surface of ceramic products as much as possible, thereby improving the utilization efficiency of the antibacterial metal constituting the metal nanoparticles. We examined further enhancement. As a result, a ceramic surface treatment agent in which metal nanoparticles with a 90% cumulative diameter D force S l 50 nm or less of particle size distribution are colloidally dispersed in a dispersion medium,

90

It has been found that it may be used as a glaze for forming a glaze layer or as a background paint for forming a sketch. Therefore, the invention described in claim 2 is characterized in that a metal nanoparticle force colloidal dispersion having a 90% cumulative diameter D force S l of 50 nm or less of the particle size distribution is dispersed in the dispersion medium.

90

It is a ceramic surface treatment agent.

[0010] The antibacterial property due to the antibacterial metal is manifested only in the antibacterial metal exposed to the surface of the glaze layer and in contact with water if it is a ceramic product having a glaze layer, for example, Antibacterial metals present in the glaze layer and the like hardly contribute to imparting antibacterial properties. Therefore, in order to increase the utilization efficiency of antibacterial metals, the proportion of antibacterial metals that are not exposed on the surface of the glaze layer or the like is reduced as much as possible, and the proportion of antibacterial metals that are exposed on the surface is relatively increased. It is important. However, the composite particles carrying antibacterial metals described in Patent Documents 1 to 3 described earlier, the silver oxide described in Patent Document 4, water-insoluble and poorly soluble silver compounds, and the like are glazes. In addition to being easily aggregated, sedimentation is likely to occur when aggregation occurs. In addition, the silver metal described in Patent Document 4 has a specific gravity greater than that of the glaze component! [0011] Therefore, a conventional ceramic product having a glaze layer formed using a glaze containing these components has been described earlier because the proportion of antibacterial metals not exposed on the surface of the glaze layer increased. Thus, combined with the large particle size of the antibacterial metal exposed on the surface, the utilization efficiency of the antibacterial metal is greatly reduced. In addition, as described above, when a glaze containing agglomerated or settled or slushy components is used in the manufacture of ceramic products, the agglomerates are crushed by vigorous stirring, or the sediments are recycled. It is necessary to frequently perform operations such as dispersion. Moreover, since the composition of the glaze is constantly changing due to aggregation and sedimentation, the exposure amount and particle size of the antibacterial metal on the surface of the glaze layer formed using the glaze and the associated antibacterial performance There is also a problem that it varies easily for each ceramic product manufactured.

[0012] On the other hand, the water-soluble silver compound described in Patent Document 4 is uniformly dissolved in a glaze that is usually aqueous, and therefore does not cause aggregation or sedimentation. However, when firing, the silver atoms generated as a result of thermal decomposition of the silver compound are used as the nucleus of precipitation, and the silver atoms are successively deposited and the silver particles gradually grow. Therefore, particularly on the surface of the glaze layer, the silver particles are liable to be volatilized and lost by the heat of firing at a stage before growing to a sufficient size. Therefore, if the ratio of silver exposed on the surface of the glaze layer is reduced, the utilization efficiency of the silver as an antibacterial metal is greatly reduced. In addition, the silver deposited in the glaze layer often causes the glaze layer to have a specific color.

[0013] On the other hand, in the ceramic surface treatment agent of the invention according to claim 2, the metal nanoparticles having a 90% cumulative diameter D force Sl of 50 nm or less of the particle size distribution are uniformly and stably present in the dispersion medium. To

90

When the ceramic surface treatment agent of the present invention is used in the manufacture of ceramic products as glazes or underpaints, it is difficult to agglomerate or settle. It is not necessary to frequently perform operations such as crushing aggregates and redispersing sediments, and even without performing the above operations, the exposure amount and particle size of the antibacterial metal and the antibacterial performance associated therewith It is possible to produce antibacterial ceramic products with a constant and.

[0014] Further, since the metal nanoparticles are not volatilized and lost even when exposed to the heat of firing, and remain on the surface of the manufactured antibacterial ceramic product, the average particle diameter of the remaining metal nanoparticles The force is ¾00 nm or less, and as described above, the specific surface area and thus the contact area with water are Combined with the large size, the utilization efficiency of the antibacterial metal constituting the metal nanoparticles in the antibacterial ceramic product can be improved more than before. Therefore, according to the ceramic surface treatment agent of the invention described in claim 2, it is possible to obtain sufficient antibacterial properties even if the amount of the antibacterial metal used is smaller than the current amount. In addition, it is possible to reliably prevent the glaze layer and the background from becoming a predetermined color and increasing the cost of ceramic products.

As the antibacterial metal forming the metal nanoparticles, among the antibacterial metals exemplified above, silver excellent in antibacterial property based on the oligodynamic effect is preferable. Therefore, the invention described in claim 3 is the ceramic surface treatment agent according to claim 2, wherein the metal nanoparticles contain at least silver. Further, when the dispersion medium is water, in order to maintain the colloidal dispersion of the metal nanoparticles in the dispersion medium more stably, the metal nanoparticles are coated with a dispersant having a hydrophilic group. In this state, it is preferably dispersed in a colloid. Therefore, the invention according to claim 4 is characterized in that the metal nanoparticles are colloidally dispersed in water as a dispersion medium in a state where they are coated with a dispersant having a hydrophilic group. The ceramic surface treatment agent according to 2 or 3.

[0016] The degree of stabilization of the colloidal dispersion of the metal nanoparticles is the total amount of the metal nanoparticles settled after 24 hours from the preparation of the dispersion containing the metal nanoparticles. It is preferably 0.1% by weight or less. Therefore, the invention according to claim 5 uses a dispersion liquid in which the amount of sedimentation of the metal nanoparticles after the lapse of 24 hours after preparation is 0.1% by weight or less of the total amount of the metal nanoparticles. 5. The ceramic surface treatment agent according to claim 2, which is prepared. The invention according to claim 6 includes a step of baking at 800 to 1600 ° C. after coating the ceramic surface treatment agent according to any of claims 2 to 5 on the surface of the ceramic product. This is a method for producing an antibacterial ceramic product. According to the production method of the present invention, the metal nanoparticle having an average particle diameter of 200 nm or less is formed on the surface simply by applying the ceramic surface treatment agent of the present invention to the surface of the ceramic product and firing in the temperature range. It is the ability to produce the antibacterial ceramic products of the present invention that are present with high productivity.

The invention's effect [0017] According to the present invention, since the utilization efficiency of the antibacterial metal is high, a novel antibacterial ceramic industry that can obtain sufficient antibacterial properties even if the amount of the antibacterial metal used is less than the current amount. It is possible to provide a product, a ceramic surface treatment agent that can be used to produce the antibacterial ceramic product, and a method for producing an antibacterial ceramic product using the ceramic surface treatment agent. Brief Description of Drawings

[0018] FIG. 1 is a scanning electron micrograph showing the surface on which silver nanoparticles are formed of the antibacterial ceramic product produced in Sample No. 2-3 of Example 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[Ceramic surface treatment agent] The ceramic surface treatment agent of the present invention used for producing the antibacterial ceramic product of the present invention is a gold having 90% cumulative particle size distribution D force of 50 nm or less in a dispersion medium.

90

The genus nanoparticles are colloidally dispersed. The 90% cumulative diameter of metal nanoparticles, D force is limited to 50 nm or less.

90

Even if a ceramic surface treatment agent containing various metal nanoparticles is applied to the surface of a ceramic product base or a glaze layer formed on the surface using, for example, a base paint or a glaze, This is because there are minute metal nanoparticles having an average particle diameter of 200 nm or less on the surface, and the antibacterial ceramic product of the present invention with high utilization efficiency of the antibacterial metal cannot be produced.

[0020] That is, the 90% cumulative diameter D exceeds the above range, the metal nanoparticles having a large particle diameter,

90

Since the colloidal dispersion cannot be stably performed in the ceramic surface treatment agent, the ratio of metal nanoparticles exposed on the surface of the manufactured antibacterial ceramic product is reduced because it aggregates or settles. Moreover, when the ceramic surface treatment agent containing metal nanoparticles having a large particle diameter is used, it is difficult to make the average particle diameter of the metal nanoparticles formed on the surface of the antibacterial ceramic product 200 nm or less. For this reason, the antibacterial ceramic product has a small proportion of metal nanoparticles exposed on the surface of the antibacterial ceramic product, and the average particle diameter of the exposed metal nanoparticles exceeds 200 nm and the specific surface area is small. In this case, the utilization efficiency of the antibacterial metal constituting the metal nanoparticles is reduced. The 90% cumulative diameter D is preferably 40 nm or more even within the above range. Also, metal nanoparticles, grains

90

The median diameter D of the degree distribution is preferably lOOnm or less. Particle size of metal nanoparticles In the present invention, the 90% cumulative diameter D and the median diameter D of the distribution are the laser Doppler method.

90 50

It is determined from the particle size distribution of the metal nanoparticles measured using a particle size distribution measuring device applying the above.

[0021] As described above, the metal nanoparticles are one kind of antibacterial metal such as silver, copper, tin, zinc, etc. that can exhibit antibacterial properties by an oligodynamic effect, or two or more kinds. In addition to the above-mentioned alloy, it can also be formed from an alloy of one or more of the antibacterial metals with other metals. In particular, as described above, it is preferable to form the metal nanoparticles from a silver simple substance or an alloy containing silver having excellent antibacterial properties based on the oligodynamic effect. If the metal nanoparticles are made of silver and other antibacterial metals or alloys with other metals, considering the more effective expression of antibacterial properties due to silver, the silver content is It is preferably 50% by weight or more, particularly 80% by weight or more of the total amount of the alloy.

[0022] Examples of metals other than the antibacterial metal that form an alloy with silver include platinum, palladium, rhodium, iridium, nickel, and iron. Since these metals all have a higher melting point than silver, the melting point of the alloy is increased, and the metal nanoparticles are prevented from growing due to, for example, fusing due to heat during firing, and thus the antibacterial ceramic industry. It works to prevent the average particle size of the metal nanoparticles exposed on the surface of the product from becoming too large. In addition, the metal forms an alloy with silver, thereby preventing oxidation or so-called migration and maintaining the antibacterial property of silver for a long period of time. The metal nanoparticles may have a composite structure in which the surface of core particles made of any metal is covered with a skin layer made of silver, an alloy containing silver, or the like.

[0023] The metal nanoparticles can be produced by various conventionally known methods such as a high temperature treatment method called an impregnation method, a liquid phase reduction method, and a gas phase method. Among these, in order to produce metal nanoparticles by the liquid phase reduction method, for example, a water-soluble metal compound that is a source of metal ions forming the metal nanoparticles and a dispersant are dissolved in water. In addition, a reducing agent may be added, and the metal ions may be preferably subjected to a reduction reaction with stirring for a certain period of time. Further, in order to produce metal nanoparticles made of an alloy by a liquid phase reduction method, two or more water-soluble metal compounds that form the alloy and are sources of at least two kinds of metal ions. May be used in combination. Furthermore, in order to produce metal nanoparticles having a composite structure, The deposition of the core material particles and the deposition of the coating layer on the surface of the core material particles may be sequentially performed by a liquid phase reduction method. The metal nanoparticles produced by the liquid phase reduction method are characterized by having a spherical or granular shape, a sharp particle size distribution, and a small particle size.

[0024] Examples of the water-soluble metal compound that is a source of metal ions include silver nitrate (I) [AgNO] and silver methanesulfonate [CH 2 SO Ag] in the case of silver. In the case of copper, copper nitrate (II) [Cu (NO)], copper sulfate (Π) pentahydrate [CuSO · 5Η〇] and the like can be mentioned. In the case of tin, tin chloride (IV) pentahydrate [SnCl · 5Η〇] can be mentioned. In the case of zinc, zinc chloride (ZnCl), zinc sulfate heptahydrate (ZnSO · 7H O) And zinc nitrate hexahydrate [Zn (NO 3) · 6H 2 O] and the like. In the case of platinum, dinitrodiammine platinum (II) (Pt (NO) (NH

)), Hexachloroplatinum (IV) acid hexahydrate (H [PtCl] · 6Η Ο), etc. In the case of palladium, palladium nitrate (Π) nitric acid solution [Pd (NO) / H 0] And palladium chloride (II) solution [PdCl].

In the case of rhodium, rhodium (III) chloride trihydrate [RhCl · 3Η0], rhodium nitrate (III) solution [Rh (NO)] and the like can be mentioned. In the case of iridium, iridium chloride ( IIlKlrCl] etc. In the case of nickel, nickel chloride (Π) hexahydrate [NiCl · 6Η 0], nickel nitrate (Π) hexahydrate [Ni (NO) · 6Η 0], etc. In the case of iron, iron nitrate (III) hexahydrate, nonahydrate (Fe (NO) · 6Η 0, 9H O), iron chloride (Π) tetrahydrate (FeCl · 4Η Ο) , Iron sulfate (七) heptahydrate (FeSO · 7Η Ο), acetylacetone iron (III) (Fe [CH (COCH)]) and the like.

[0026] As the reducing agent, any of various reducing agents capable of reducing metal ions and precipitating them as metal nanoparticles in a liquid phase reaction system can be used. Examples of the reducing agent include sodium borohydride, sodium hypophosphite, hydrazine, and transition metal ions (trivalent titanium ions, divalent cobalt ions, etc.). However, in order to make the 90% cumulative diameter D of the metal nanoparticles to be deposited as small as possible even within the range of 150 nm or less as described above, the reduction of metal ions and the deposition rate should be slowed. Is effective, and in order to slow down the reduction and precipitation rate, it is preferable to select and use a reducing agent having a reducing power as weak as possible. [0027] Examples of the reducing agent having a weak reducing power include alcohols such as methanol, ethanol, 2-propanol, and ascorbic acid, as well as ethylene glycol, glutathione, organic acids (taenoic acid, malic acid, Tartaric acid, etc.), reducing saccharides (glucose, galactose, mannose, funolectus, sucrose, manoletose, raffinose, starchy etc.), sugar alcohols (sorbitol, etc.), among others, reducing saccharides, Sugar alcohols as derivatives thereof are preferred.

[0028] As the dispersant, various dispersants are used that have a hydrophilic group, have good solubility in water, and can disperse precipitated metal nanoparticles in water. it can . In the reaction system, the dispersing agent coats the surface of the deposited metal nanoparticles to prevent aggregation of the metal nanoparticles and maintain the dispersion. The liquid phase reaction system in which the metal nanoparticles are deposited is a starting point for preparing a ceramic surface treatment agent in a liquid phase state in which only impurities are removed without separating the metal nanoparticles from the reaction system. It can be used as a raw material. At that time, the dispersant remains almost removed in the impurity removal step, and covers the surface of the metal nanoparticles in the prepared ceramic surface treatment agent as described above, thereby agglomerating. And can continue to function as a dispersant to maintain dispersion

[0029] Dispersion homogeneous IJi, number average molecular weight Μπ force 1000 to 800,000, particularly 2000 to 300,000 force S is preferable. When the number average molecular weight Μη is less than the above range, there is a possibility that the effect of maintaining the dispersion by preventing the aggregation of the metal nanoparticles by the dispersing agent may not be obtained. Moreover, when the said range is exceeded, there exists a possibility that the handling at the time of the application | coating to a base surface etc. may become easy because the viscosity of a ceramics surface treatment agent becomes high too much. Hydrophilic groups introduced into the dispersant include oxygen-containing functional groups such as oxy group (—〇—), hydroxy group (-基), carboxy group (—COOH), amino group (ΝΗ), imino group (> ΝΗ), Ammonium group (-ΝΗ ⁺ )

Examples include nitrogen-containing functional groups such as 2 4, sulfur-containing yellow functional groups such as sulfanyl group (one SH), sulfandyl group (one S), and the like. The dispersant may have one kind of the hydrophilic group, or two or more kinds.

[0030] Suitable dispersants include, for example, poval (polybulal alcohol), polyethylene oxide, polypropylene oxide, polyethyleneimine, polybulylpyrrolidone, polyalkane. Examples include thiol and maleic acid-based copolymers. The dispersant can be added to the reaction system in the form of a solution dissolved in water or a water-soluble organic solvent. The amount of the dispersing agent added is such that when the dispersing agent is subsequently used as a dispersing agent that coats the surface of the metal nanoparticles and prevents its aggregation in the ceramic surface treatment agent, the ceramic surface treatment The content of the dispersant, expressed as a percentage of the amount of metal nanoparticles, is preferably !!-20% by weight, in particular 8-8%, preferably 15% by weight. If the content of the dispersant is less than the above range, the effect of preventing the aggregation by covering the surface of the metal nanoparticles in the reaction system and in the ceramic surface treatment agent by the dispersant cannot be sufficiently obtained. ! / There is a risk.

[0031] Also, for example, when the ceramic surface treatment agent is a glaze, if the content of the dispersant exceeds the above range, an excessive dispersant is sintered in the glaze component contained in the glaze during firing. May be hindered to reduce the denseness of the formed glaze layer. Further, in the case of a base paint, there is a risk that the density of the base picture formed, the adhesion to the glaze layer, and the like may be reduced. To adjust the 90% cumulative diameter D of the particle size distribution of the metal nanoparticles, the metal compound, the dispersion

90

In addition to adjusting the type and mixing ratio of the agent and the reducing agent, the stirring speed, temperature, time, pH, etc. may be adjusted when the metal compound is reduced. For example, the pH of the reaction system is 7 to 13 considering the formation of metal nanoparticles with a 90% cumulative diameter D as small as possible.

90

Is preferred. In order to adjust the pH of the reaction system to the above range, a pH adjuster is used. Examples of the pH adjuster include various acids such as nitric acid and various alkalis such as ammonia depending on the pH value to be adjusted.

[0032] The metal nanoparticles precipitated in the liquid phase reaction system are subjected to steps such as mashing, washing, drying, and crushing, and then once powdered, water, a dispersant, and further necessary Accordingly, a ceramic surface treatment agent may be prepared by blending with a water-soluble organic solvent at a predetermined ratio, but as described above, a liquid-phase reaction system in which metal nanoparticles are precipitated is used. It is preferable to prepare a ceramic surface treatment agent using as a starting material. That is, gold

From the reaction system of the liquid phase containing the metal nanoparticles after the metal nanoparticles are precipitated, the dispersant for coating the surface of the metal nanoparticles, and the water used for the reaction, ultrafiltration and centrifugation After adjusting the concentration of the metal nanoparticles by removing impurities by performing treatments such as washing with water, electrodialysis, etc., and concentrating to remove water or adding water as needed. Ceramic table A ceramic surface treatment agent is prepared by blending other components constituting the surface treatment agent in a predetermined ratio. This method can prevent the generation of coarse and irregular particles due to the aggregation of metal nanoparticles.

[0033] Other components constituting the ceramic surface treatment agent include water-soluble organic solvents for adjusting the viscosity and vapor pressure of the ceramic surface treatment agent. As the water-soluble organic solvent, various organic solvents that are water-soluble can be used. Specific examples thereof include alcohols such as methanol, ethanol and 2-propanol, ketones such as acetone and methyl ethyl ketone, ethylene glycol monomethino ethenore, ethylene glycol monomethino reetor and the like. Daricol ethers and the like can be mentioned. The addition amount of the water-soluble organic solvent is preferably 30 to 900 parts by weight per 100 parts by weight of the metal nanoparticles. If the addition amount is less than the above range, the effect of adjusting the viscosity or vapor pressure of the dispersion by adding the organic solvent may not be sufficiently obtained. In addition, when the above range is exceeded, it is possible to sufficiently swell the dispersant with water so that the metal nanoparticles coated with the dispersant do not cause aggregation in the ceramic surface treatment agent. Dispersing effect may be hindered.

[0034] It is preferable that the amount of sedimentation of the metal nanoparticles when the dispersion has been prepared for 24 hours after preparation is 0.1% by weight or less of the total amount of the metal nanoparticles. When the amount of sedimentation exceeds the above range, the metal nanoparticles tend to settle. Therefore, when a ceramic surface treatment agent is prepared using the dispersion, the proportion of metal nanoparticles exposed on the surface formed by firing the ceramic surface treatment agent is reduced, and the use efficiency of the antibacterial metal is reduced. There is a risk of lowering or poor appearance. On the other hand, if the amount of sedimentation of the metal nanoparticles is within the above range, the stability of the colloidal dispersion of the metal nanoparticles can be improved, and the colloidal dispersion can be more uniformly dispersed in the ceramic surface treatment agent. In addition, sedimentation can be prevented. Therefore, by increasing the proportion of metal nanoparticles exposed on the surface formed by firing the ceramic surface treatment agent, the utilization efficiency of the antibacterial metal constituting the metal nanoparticles can be further improved. It becomes possible to make the appearance good. In order to adjust the amount of sedimentation, the particle diameter of the metal nanoparticles and the coating amount of the dispersant may be adjusted. In general, the smaller the particle size of the metal nanoparticles, the greater the coating amount of the dispersant. The more you decrease, the more you can reduce the amount of sediment.

[0035] << Method for Producing Antibacterial Ceramics Product >> The method for producing an antibacterial ceramic product of the present invention is as follows. After applying the ceramic surface treatment agent of the present invention to the surface of the ceramic product, 800 ~; 1600 ° It includes a step of firing with C. Specifically, for example, using the ceramic surface treatment agent of the present invention as a glaze, it is applied to the surface of a ceramic product substrate or the surface of the glaze layer formed on the surface, or the ceramic surface treatment agent. Is used as a base paint to draw a rough sketch on the surface of the glaze layer formed on the surface of the ceramic product substrate, and then fired in the above temperature range to give metal nano particles with an average particle diameter of 200 nm or less to the surface. The antibacterial ceramic product of the present invention in which particles are present is produced.

[0036] The reason why the firing temperature is limited to 800 to 1600 ° C is as follows. That is, when the firing temperature is less than the above range, for example, when the ceramic surface treatment agent is a glaze, the glaze component cannot be sufficiently sintered, so that the density of the formed glaze layer may be reduced. There is. Further, in the case of a base paint, there is a risk that the density of the formed base sketch, the adhesion to the glaze layer, and the like may be reduced. On the other hand, when the firing temperature exceeds the above range, the metal nanoparticles exposed on the surface of the glaze layer and the lower paint are volatilized by the heat of firing and are easily lost. For this reason, if the proportion of the antibacterial metal exposed on the surface of the glaze layer is reduced, the utilization efficiency may be reduced, and sufficient antibacterial properties may not be obtained. The firing temperature depends on the type of glaze component, pigment, etc., but is 1000 to 1600 even within the above range. C, especially from 1150; It's about C. The firing may be performed in an air atmosphere, or depending on the type of glaze or lower paint, it may be performed in an appropriate firing atmosphere such as a reducing atmosphere. In addition, in the case of firing in the above temperature range, the firing time is set so that the average particle diameter of the metal nanoparticles formed on the surface of the ceramic product to be produced is 200 nm or less and imparts good antibacterial properties. , 20 minutes to 30 hours is preferred!

[0037] <Antimicrobial ceramic product> The antibacterial ceramic product of the present invention that can be manufactured by the above-described manufacturing method or the like has metal nanoparticles having an average particle diameter of 200 nm or less and containing at least silver on the surface. It is characterized by that. The reason why the average particle diameter of the metal nanoparticles present on the surface is limited to 200 nm or less is as follows. That is, the average particle Within the above range, the utilization efficiency of the antibacterial metal forming the metal nanoparticles can be improved, and sufficient antibacterial properties commensurate with the amount of the antibacterial metal used can be obtained. For this reason, the amount of antibacterial metal used can be reduced, and for example, it is possible to reliably prevent the glaze layer and the background from becoming a predetermined color or increasing the cost of ceramic products. .

[0038] In consideration of obtaining better antibacterial properties, the average particle size is preferably 0.5 to 100 nm, and more preferably 0.5 to 50 nm, even within the above range. The average particle size can be determined from the particle size by direct observation. Specifically, for example, particles of at least 10 metal nanoparticles obtained by observing the surface of an antibacterial ceramic product using a high-resolution SEM (scanning electron microscope) having an observation magnification of 10,000 times or more. The average value can be obtained from the diameter to obtain the average particle diameter.

Example 1

<Synthesis of Silver Nanoparticle Dispersion> Silver nitrate (I) as a metal compound is dissolved in pure water, ammonia water is added to adjust the pH of the solution to 10, and then maleic acid as a dispersant. A copolymer (Crobacs (registered trademark) 400-21S manufactured by Nippon Kasei Co., Ltd., molecular weight: 9000, acid value: 10 OmgKOH / g) was added and dissolved, and then ethylene glycol as a reducing agent was purified. A solution dissolved in water was added to prepare a liquid phase reaction system. The concentration of each component in the reaction system was silver nitrate (I): 25 g / liter, maleic acid copolymer: 20 g / liter, reducing agent: 120 g / liter.

[0040] The reaction system was reacted at 85 ° C for 180 minutes with vigorous stirring at a force and stirring speed of lOOrpm to precipitate silver nanoparticles, and then diluted with pure water by ultrafiltration treatment. The impurities were removed by repeating the above to obtain a dispersion liquid in which the silver nanoparticles were colloidally dispersed. The 90% cumulative diameter D of the particle size distribution of the silver nanoparticles in the above dispersion is determined using the laser Doppler method.

90

It was 45 nm as determined from the particle size distribution of the silver nanoparticles measured using a distribution measuring device [Nanotrack (registered trademark) UPA-EX150 manufactured by Nikkiso Co., Ltd.]. Further, the composition of the silver nanoparticles was measured using an inductively coupled high-frequency plasma emission spectrometer [CIROS-120 manufactured by Rigaku Corporation], and the silver content was 100%.

[0041] The solid content concentration in the dispersion is 10% by weight, and the dispersion per 100 parts by weight of silver nanoparticles is The amount of the agent was 9 parts by weight. Further, the dispersion lOOOOg was collected in a glass container, and the glass container was allowed to stand for 24 hours in a thermostatic bath maintained at 25 ° C. in a state where the glass container was sealed with a polypropylene resin cap. The supernatant was removed with a dropper, and the sediment settled on the bottom of the glass container was collected, dried at 105 ° C for 3 hours, and weighed with a precision balance.The sedimentation amount was 0% of the total amount of silver nanoparticles. It was confirmed to be 03% by weight.

<Preparation of ceramic surface treatment agent> 35.58 parts by weight of feldspar, 13.5 parts by weight of lime, 9.7 parts by weight of clay, and 40.2 parts by weight of silica sand as glaze components Were mixed with 100 parts by weight of water and pulverized with a centrifugal ball mill to form a slurry. Next, the previously prepared dispersion of silver nanoparticles is added to the slurry so that the ratio of silver nanoparticles in the total amount of solids is 0.02 wt%, and mixed to obtain a ceramic surface treatment agent. A glaze was prepared. For the glaze, it is expressed as a percentage of the amount of the dispersing agent relative to the amount of metal nanoparticles from the content of the dispersant obtained by performing TG-MASS analysis and the content of silver obtained by performing ICP analysis. The content was determined to be 3.3% by weight.

[0043] <Manufacture of antibacterial ceramic products> The glaze prepared above was sprayed onto the surface of the tile substrate, dried, and then heated to 1200 ° C in an air atmosphere using an electric furnace. A sample of antibacterial ceramic product with a glaze layer was produced by baking for a minute. Then, the surface of the glaze layer of the sample is photographed using a high-resolution SEM (scanning electron microscope) to obtain image data, the image data is subjected to image analysis, and all the images captured in the image data are captured. As a result of obtaining the individual particle diameters of the silver nanoparticles and calculating the average value as the average particle diameter, it was 30 nm.

<Evaluation of antibacterial properties> After 1 ml of a bacterial solution of Staphylococcus aureus was dropped on the surface of the glaze layer of the sample, a sterilized polyethylene film was placed and allowed to stand at 25 ° C for 24 hours. After equation (1):

Country

^^ _{(θ / λ} control viable count—sample viable count γ.

When the sterilization rate was determined by eradication (.) = X ^{1 0 0 (1)} , it exceeded 99% and the antibacterial property was good.

Example 2 In accordance with the method described in Example 1, as shown in Table 1, five types of silver nanoparticle dispersions having different 90% cumulative diameter D of the particle size distribution of silver nanoparticles were prepared, and the silver nanoparticles were Dispersion

90

The glaze was prepared under the same conditions as in Example 1 to produce an antibacterial ceramic product, and then the sterilization rate was determined to evaluate the antibacterial property. The results are shown in Table 1.

[table 1]

table 1

[0046] From Table 1, the 90% cumulative diameter D of the particle size distribution of silver nanoparticles in the glaze was set to 150 nm or less.

90

When the average particle size of silver nanoparticles formed on the surface of antibacterial ceramic products was 200 nm or less, it was confirmed that good antibacterial properties can be imparted. In addition, when the surface of the antibacterial ceramic product manufactured with Sample No. 2-3 in Table 1 was observed with a scanning electron microscope, fine silver nanoparticles were formed on the surface as shown in FIG. It was confirmed that Example 3

[0047] Based on the method described in Example 1, the 90% cumulative diameter D of the particle size distribution of the silver nanoparticles was 80

A silver nanoparticle dispersion having 90 nm and a sedimentation amount of 0.06% by weight of the total amount of silver nanoparticles was prepared. Using the silver nanoparticle dispersion, the content of the dispersant was 1.2% by weight. After the preparation of the glaze, an antibacterial ceramic product was manufactured in the same manner as in Example 1 except that the firing conditions shown in Table 2 were used, and the antibacterial properties were evaluated by obtaining the sterilization rate. did. The results are shown in Table 2.

[Table 2] Table 2

[0048] From Table 2, when the firing temperature is 800 to 1600 ° C and the time is 30 hours or less, the average particle diameter of the silver nanoparticles formed on the surface of the antibacterial ceramics product is 200 nm or less, which is good Antibacterial

It was confirmed that it could be granted. The antibacterial ceramic products of Samples 3-6 were found to have been lost due to volatilization by firing at high temperature, and no silver nanoparticles were observed even when the surface was observed.

Example 4

[0049] According to the method described in Example 1, the 90% cumulative diameter D of the particle size distribution of the silver nanoparticles was 33.

After preparing a silver nanoparticle dispersion liquid of 90 nm and using the silver nanoparticle dispersion liquid, as shown in Table 3, three types of glazes with different dispersant contents were prepared, and then the glaze was used. The antibacterial ceramic product was manufactured under the same conditions as in Example 1, the sterilization rate was determined, and the antibacterial property was evaluated. In addition, the appearance of the manufactured antibacterial ceramic products was observed. The results are shown in Table 3.

[Table 3]

Table 3

[0050] From Table 3, the content of the dispersant is from! To 20% by weight, considering the appearance of antibacterial ceramic products; It was confirmed that it was preferred.

Example 5

In accordance with the method described in Example 1, as shown in Table 4, it contains metal nanoparticles made of silver or a combination of silver and palladium, and 90% cumulative diameter of the particle size distribution of the metal nanoparticles D

After preparing a metal nanoparticle dispersion in which 90 is 35 to 40 nm, and using the silver nanoparticle dispersion, a glaze having a dispersant content of 12.5 to 15.0 wt% is prepared, Using glaze, antibacterial ceramic products were produced under the same conditions as in Example 1, the sterilization rate was determined, and antibacterial properties were evaluated. As the dispersant, polyacrylic acid (molecular weight 5000) was used. The results are shown in Table 4.

[Table 4]

Table 4

From Table 4, it was confirmed that in the case of metal nanoparticles made of an alloy, the silver content is preferably 50% by weight or more, particularly 80% by weight or more in the total amount of the alloy!

Claims

The scope of the claims

[1] An antibacterial ceramic product characterized in that metal nanoparticles containing at least silver and having an average particle diameter of 200 nm or less exist on the surface.

[2] Metal nanoparticle force colloid with 90% cumulative diameter D of particle size distribution of 150 nm or less in dispersion medium

90

A ceramic surface treatment agent that is dispersed!

[3] The ceramic surface treatment agent according to claim 2, wherein the metal nanoparticles contain at least silver.

[4] The ceramic surface treatment according to claim 2 or 3, wherein the metal nanoparticles are colloidally dispersed in water as a dispersion medium in a state of being coated with a dispersant having a hydrophilic group. Agent.

[5] The method is characterized by being prepared using a dispersion in which the amount of sedimentation of the metal nanoparticles after the lapse of 24 hours is 0.1% by weight or less of the total amount of the metal nanoparticles. Claim

2! /, 4! /, Ceramic surface treatment agent as described in any of the above.

[6] An antibacterial ceramic industry comprising a step of applying a ceramic surface treatment agent according to any one of claims 2 to 5 to a surface of a ceramic product, followed by baking at 800 to 1600 ° C. Product manufacturing method.