JP2009001505A - Method for producing antibacterial agent microparticle, antibacterial coating and antibacterial heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simply and stably producing silver carbonate microparticles having ≤5 μm particle diameter with a high silver content and to further provide a technique for developing antibacterial properties over a long period of time with the resultant silver carbonate microparticles. <P>SOLUTION: A solution A containing silver ions is mixed with a solution B containing carbonate ions in the presence of colloidal particles under specific conditions to further form a resin coating comprising the resultant silver carbonate microparticles. A heat exchanger is provided by applying the resin coating to a heat exchange part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing antibacterial fine particles having a particle size of 5 μm or less and a silver content of at least 15% by mass, an antibacterial paint capable of eluting silver ions of 50 ppb or more in the generated condensed water, and for a long period of time. The present invention relates to an antibacterial heat exchanger capable of preventing the occurrence of mold that propagates on the fin surface.

  Antibacterial agents using silver (silver-based antibacterial agents) are added to paints and resin products that want to give antibacterial functions by dispersing in the paint as fine particle powders or kneading them into the resin. Has been. In this case, the coating film or resin should be coated or coated to ensure the smoothness of the painted surface or resin surface, or not to deteriorate the heat transfer characteristics of the product to be coated or resin coated. It is desired that the film be a thin film of several μm or less. For this reason, the silver antibacterial agent particles used in such paints and resins are required to be fine particles having a particle diameter of several μm or less.

  Silver antibacterial particles usually include particles having a particle diameter of several μm or less, such as zeolite, silica gel, alumina, or phosphate, with a silver compound supported on those powder particles. It is known (for example, refer to Patent Documents 1 to 5). Although the antibacterial action of the silver antibacterial agent is due to silver, it is difficult to increase the silver content of the conventional silver antibacterial agent particles due to the presence of the carrier, and usually remains at 10% by mass or less.

  For this reason, in the production of silver-based antibacterial agent particles in which a silver compound is supported on a carrier, in order to maintain the antibacterial action for a predetermined period, the amount of silver-based antibacterial agent originally added to the product is required. An amount of 10 times or more on a mass basis is usually required.

  Thus, in the conventional silver-based antibacterial agent, since silver is supported on a carrier, the presence of this carrier maintains the antibacterial effect for a longer period, that is, increases the silver density in the product. It was a big restriction. Conversely, using metallic silver particles having a silver content of 100% by mass as antibacterial agent particles makes it difficult to obtain a sufficient antibacterial effect because the solubility of silver is extremely low. For this reason, such antibacterial agent particles have not been put to practical use.

  On the other hand, silver carbonate is a silver compound having a lower solubility in silver, but has a higher silver solubility than metal silver and has a function as an antibacterial agent. Moreover, the silver content rate of silver carbonate is 78 mass%, and if silver carbonate itself is made into fine particles, silver-based antibacterial agent particles having a much higher silver content than conventional ones are obtained. Silver carbonate, like many silver compounds, is sensitive and discolors in the presence of light. Except for applications where discoloration is a problem, it is highly durable silver-based antibacterial particles. It can be expected to be used as

  It is known that silver carbonate is finely divided to a particle size of 5 μm or less by a mechanical grinding method such as a jet mill or a ball mill. However, this method has a low yield due to the low hardness of silver carbonate, and there remains room for study from the viewpoint of production efficiency and cost.

  In addition, for antibacterial agents containing silver carbonate, a production method is known in which a sparingly water-soluble silver salt is precipitated from silver ions, a counter ion that produces silver ions and a sparingly water-soluble silver salt, a core, and a solvent (for example, , See Patent Document 6). However, this method still has room for study from the viewpoint of controlling the silver ion content in the antibacterial agent and the particle size of the antibacterial agent.

  Furthermore, regarding the use of the antibacterial agent, for example, Patent Document 5 describes a method of applying a paint prepared by kneading a metal antibacterial agent into a resin material to the surface of an air conditioner equipment. In such a method, when an organic resin material such as an epoxy resin is used as the resin material, it is necessary to consider the work environment in the paint preparation and application process to the air conditioning equipment, and an investment in ventilation equipment is required. It is. Thus, the above method still has room for study from the viewpoint of consideration of the work environment.

In addition, as an antibacterial method inside the air conditioner, a bar-shaped special plate made using a silver-based antibacterial agent is sandwiched between the fins at the top of the heat exchanger, and silver ions are eluted together with the condensed water. A method for antibacterial the entire flowing water path of the drain hose is known (see, for example, Patent Document 7). It is possible to increase the total silver ion amount by making it into a rod shape, so it is possible to ensure the durability of the antibacterial effect, but installing a rod-shaped plate inside the fin will obstruct and shield the airflow, and equipment In order to increase the internal pressure loss, there remains room for consideration from the viewpoint of the effect on the operating efficiency of the air conditioning equipment.
JP-A-6-24921 JP-A-8-67835 JP-A-8-157750 JP 2004-137241 A JP 2004-161632 A JP 2005-139113 A JP 2001-343196 A

  In the present invention, silver carbonate fine particles having a particle size of 5 μm or less and having a high silver content can be easily and stably obtained, which has been difficult by such a method of supporting a silver compound on a powder or mechanical grinding. It is an object of the present invention to provide a manufacturing method.

  It is another object of the present invention to provide an antibacterial film which can use silver fine antibacterial agent fine particles and can elute silver ions of 50 ppb or more for a long time with a thin coating film, and its use.

  The present invention relates to a method for obtaining silver carbonate fine particles by mixing a solution containing silver ions as A, a solution containing carbonate ions as B, and mixing solution A and solution B in the presence of colloidal particles. Provided is a method for obtaining silver carbonate fine particles having a particle size of 5 μm or less by adjusting conditions such as the number and concentration of particles and quantitative conditions of colloidal particles and silver.

That is, the present invention relates to a method for producing silver carbonate fine particles by mixing a solution A containing silver ions and a solution B containing carbonate ions in the presence of colloidal particles. The particle number concentration with respect to the solvent mass of the colloidal particles in the mixed solution obtained by mixing the solution A and the solution B is y [number / g], and the ratio of the number of silver atoms to the number of colloidal particles in the mixed solution is z. When the particle number concentration y of the colloidal particles is not less than the value obtained by the following formula 1 and not more than the value obtained by the following formula 2, the ratio z of the number of silver atoms is less than the value obtained by the following formula 3. A method for mixing solutions A and B in the presence of colloidal particles is provided.
Formula 1) y = 1.16 × 10 ¹⁷ × (1 / x) ^1.9
Formula 2) y = 9.23 × 10 ¹⁹ × (1 / x) ^3.0
Formula 3) z = k * (175.3x < ² > + 2196.3x + 2793)
(In Formula 3, k is 1.)

  The present invention also provides a coating material for an antibacterial resin film containing silver carbonate fine particles having a particle size of 5 μm or less and a silver content of 15% by mass or more, and a resin, wherein the content of the silver carbonate fine particles is The antibacterial resin film coating is 14 to 88% by mass in the antibacterial resin film.

  Furthermore, the present invention has a heat exchange part for heating or cooling a fluid and an antibacterial resin film formed on the surface of the heat exchange part, and water is present on the surface of the heat exchange part during heat exchange. In the heat exchanger, the antibacterial resin film provides an antibacterial heat exchanger which is an antibacterial resin film formed by applying the antibacterial resin film paint of the present invention.

  According to the present invention, silver carbonate fine particles having a particle size of 5 μm or less are easily and stably produced as silver antibacterial fine particles having a silver content of 15% by mass or more and a higher silver content than conventional. can do.

  In addition, according to the present invention, it is possible to provide an antibacterial coating material capable of forming a thin film that elutes silver ions of 50 ppb or more for a long time in the presence of water, and a heat exchanger having an antibacterial action due to silver carbonate fine particles.

In the method for producing silver carbonate fine particles in the present invention, the solution A containing silver ions and the solution B containing carbonate ions are mixed in the presence of colloidal particles to produce silver carbonate fine particles. The particle diameter is x [nm], the particle number concentration with respect to the solvent mass of the colloidal particles in the mixed solution in which the solution A and the solution B are mixed is y [particles / g], and the silver atoms with respect to the number of colloidal particles in the mixed solution The number ratio y of colloidal particles is not less than the value obtained by the following formula 1 and not more than the value obtained by the following formula 2, and the ratio z of the number of silver atoms is z The solutions A and B are mixed in the presence of colloidal particles so as to be less than the value obtained by Equation 3. In the following formula 3, k is 1.
Formula 1) y = 1.16 × 10 ¹⁷ × (1 / x) ^1.9
Formula 2) y = 9.23 × 10 ¹⁹ × (1 / x) ^3.0
Formula 3) z = k * (175.3x < ² > + 2196.3x + 2793)

  The particle diameter x of the colloidal particles is a value representative of the size of the colloidal particles used. Examples of the particle diameter x of the colloidal particles include an average particle diameter. In the present invention, commercially available particles or commercially available colloidal aqueous solutions (sols) can be used for the colloidal particles, and the particle diameter x of the colloidal particles is the manufacturer's nominal value (catalog value) for such commercially available products. May be.

  The particle diameter x of the colloidal particles is usually 1 to 500 nm and is not particularly limited. However, for colloidal particles, the smaller the particle diameter at the same mass concentration, the higher the concentration of the number of colloidal particles. For this reason, from the viewpoint of mass-producing silver carbonate fine particles while satisfying the condition of the value of the formula 1 or more and the value of the formula 2 or less, it is preferable to use particles having a small particle diameter as the colloid particles. Practically, the colloidal particle diameter is more preferably less than 50 nm, even more preferably 5 to 50 nm, and even more preferably 5 to 30 nm.

  The particle number concentration y of the colloidal particles is the number [number] of colloidal particles with respect to the mass [g] of the liquid medium (that is, solvent, for example, water) in the mixed solution obtained by mixing the solution A and the solution B. The number of colloidal particles in the mixed solution is as follows. When a commercially available colloidal solution is used for the colloidal particles, the particle diameter x of the colloidal particles in the commercially available colloidal solution, the specific gravity of the commercially available colloidal solution, and the commercially available colloidal solution. It can obtain | require from the mass density | concentration of the colloid particle in this, and can adjust by diluting this commercial colloid solution with water of known mass.

  When the particle number concentration y of the colloidal particles is small, the particle size of the obtained silver carbonate fine particles is large. As described above in the background art, the silver carbonate fine particles are desired to have a particle size of several μm or less when dispersed in a film. When the particle number concentration y of the colloidal particles is not less than the value obtained by the above formula 1, silver carbonate fine particles having a particle diameter of 5 μm or less are obtained. Further, when the particle number concentration y of the colloidal particles is equal to or less than the value obtained by Equation 2, gelation (solidification) of the mixed solution is prevented.

  When the ratio z of the number of silver atoms to the number of colloidal particles in the mixed solution is less than the value of Formula 3, enlargement of the silver carbonate fine particles is prevented. The ratio z of the number of silver atoms to the number of colloidal particles in the mixed solution is equal to or greater than the value of Equation 3 when the coefficient k of Equation 3 is 0.6 and the value of Equation 3 when k is 1. Preferably less than the value of Equation 3 when k is 0.8 and more preferably less than the value of Equation 3 when k is 1, and Equation 3 when k is 1. More preferably, it is less than this value.

The production mechanism of silver carbonate fine particles by the method of the present invention is a mechanism in which, in the mixed solution, silver carbonate is deposited on the surface of the colloidal particles as nuclei, and the original particles grow to produce silver carbonate fine particles. Conceivable. If the ratio z of the number of silver atoms to the number of colloidal particles in the mixed solution is too large, the precipitation of silver carbonate and the growth of the original particles on the surface of the colloidal particles may proceed excessively, and the silver carbonate fine particles may become enormous. . The ratio z of the number of silver atoms to the number of colloidal particles depends on the particle diameter x of the colloidal particles, but is generally about 10 ⁵ or less. From the viewpoints of control of mass production and mass productivity of silver carbonate fine particles.

  The number of silver atoms is the sum of the number of silver ions in the mixed solution and the number of silver atoms that are not ions. The number of silver atoms in the mixed solution is the sum of the number of silver atoms in solution A and solution B. Hereinafter, calculation methods of the number of silver atoms, the number of colloidal particles, and the concentration of colloidal particles in the mixed solution will be described.

For example, when the silver compound is not contained in the solution B, the number of silver atoms can be obtained by the following formula 4.
Formula 4) Nag = mac × Wac × NA / Mac

In Formula 4, Nag is the number of silver atoms in the mixed solution [mac], mac is the number of silver atoms in one molecule of the silver compound used in the preparation of solution A, and Wac is in the preparation of solution A. It is the mass [g] of the silver compound used, NA is the Avogadro number (6.02 × 10 ²³ [pieces]), and Mac is the molecular weight of the silver compound used in the preparation of the solution A.

For example, when the colloidal particles are contained in each of the solutions A and B and the solutions A and B are mixed to obtain the mixed solution, the number of colloidal particles can be obtained by the following formula 5.
Formula 5) Np = Np (A) + Np (B)

  In Formula 5, Np is the number of colloidal particles [number] in the mixed solution, Np (A) is the number of colloidal particles in solution A [number], and Np (B) is the number of colloidal particles in solution B [number]. Pieces].

Np (A) and Np (B) can be obtained by the following equations 6 and 7.
Formula 6) Np (A) = Wp (A) / {ρp (A) × 4/3 × π × (dp (A) / 2) ³ }
Expression 7) Np (B) = Wp (B) / {ρp (B) × 4/3 × π × (dp (B) / 2) ³ }

In Equation 6, Wp (A) is the mass [g] of the colloidal particles in the solution A, and ρp (A) is the density [g / cm ³ ] of the colloidal particles in the commercially available colloidal solution used in the solution A. , Dp (A) is the particle size [cm] of the colloidal particles of the commercially available colloidal solution used for solution A. In Formula 7, Wp (B) is the mass [g] of the colloidal particles in the solution B, and ρp (B) is the density [g / cm ³ ] of the colloidal particles in the commercially available colloidal solution used for the solution B. Dp (B) is the particle diameter [cm] of the colloidal particles of the commercially available colloidal solution used for the solution B.

Wp (A) and Wp (B) can be obtained from the following equations 8 and 9, and ρp (A) and ρp (B) can be obtained from the following equations 10 and 11.
Formula 8) Wp (A) = Csol (A) × Wsol (A) / 100
Formula 9) Wp (B) = Csol (B) × Wsol (B) / 100
Formula 10) ρp (A) = Csol (A) × ρsol (A) / (1−ρsol (A) + ρsol (A) × Csol (A))
Formula 11) ρp (B) = Csol (B) × ρsol (B) / (1−ρsol (B) + ρsol (B) × Csol (B))

In Formulas 8 and 10, Csol (A) is the colloid mass concentration [% by mass] of the commercially available colloidal solution used in Solution A. In Formulas 9 and 11, Csol (B) is the commercially available colloid used in Solution B. It is the colloid mass concentration [% by mass] of the solution. In Formula 8, Wsol (A) is the mass [g] of the commercially available colloidal solution in solution A, and in Formula 9, Wsol (B) is the mass [g] of the commercially available colloidal solution in solution B. . In Formula 10, ρsol (A) is the specific gravity [g / cm ³ ] of the commercially available colloidal solution used in Solution A, and in Formula 11, ρsol (B) is the specific gravity of the commercially available colloidal solution used in Solution B. [G / cm ³ ]. For ρsol (A) and ρsol (B), the physical property values attached to the commercial products are used as they are, or calculated from the physical property values, or the volume per volume of the colloidal solution obtained by diluting the commercial colloidal solution or the commercial colloidal solution. It can be determined by measuring the mass.

The concentration of colloidal particles with respect to the solvent mass of colloidal particles in the mixed solution can be obtained by the following formula 12.
Formula 12) Cp = Np / Wm

  In Formula 12, Cp is the particle number concentration [number / g] of colloid with respect to the mass of solvent (water) of colloidal particles in the mixed solution, and Wm is the mass [g] of water (solvent) of the mixed solution.

Wm can be obtained by the following equation (13).
Formula 13) Wm = Ww (A) + Wdw (A) + Ww (B) + Wdw (B)

  In Formula 13, Ww (A) is the mass [g] of the solvent (water) in the commercially available colloidal solution used for Solution A, and Wdw (A) was used for diluting the commercially available colloidal solution when preparing Solution A. Solvent (water) mass [g], Ww (B) is the mass (g) of solvent (water) in the commercially available colloidal solution used for solution B, and Wdw (B) is commercially available when preparing solution B It is the mass [g] of the solvent (water) used for dilution of the colloidal solution.

Wdw (A) and Wdw (B) can be obtained by the following equations 14 and 15.
Formula 14) Ww (A) = (1-Csol (A)) × Wsol (A)
Formula 15) Ww (B) = (1-Csol (B)) × Wsol (B)

Moreover, the colloid mass concentration of the solution A or the solution B which diluted the commercially available colloid solution can be calculated | required by following formula 16 and 17. However, in Formula 16, Cdsol (A) is the colloid mass concentration [mass%] of the solution A which diluted the commercially available colloid solution, and in Formula 17, Cdsol (B) is the colloid of the solution B which diluted the commercially available colloid solution. Mass concentration [mass%].
Expression 16) Cdsol (A) = Wp (A) / (Wdw (A) + Wp (A)) × 100
Expression 17) Cdsol (B) = Wp (B) / (Wdw (B) + Wp (B)) × 100

  The mixing of the solutions A and B and the colloidal particles in the present invention is not particularly limited as long as the silver ions in the solution A and the carbonate ions in the solution B can be mixed in the presence of the colloidal particles. In the present invention, the solution A and the solution B may be mixed with a commercially available colloidal solution or a colloidal solution obtained by diluting it, or a mixed solution of one of the solutions A and B and the colloidal solution, and the solutions A and B. Any one of the above may be mixed, or a mixed solution of the solution A and the colloidal solution may be mixed with a mixed solution of the solution B and the colloidal solution.

  The mixing of the solution A and the solution B in the presence of colloidal particles depends on the particle size of the colloidal particles, for example, the amount of colloidal particles, the mass concentration of the colloidal solution, the amount of water in the solution A, the silver ions in the solution A By adjusting the amount of water, the amount of the water-soluble silver compound dissolved in the solution A, the amount of water in the solution B, etc., the mixing conditions based on the above formulas 1 to 3 can be adjusted. However, the method for realizing the mixing condition is not limited to these.

  In the present invention, it is preferable that the solutions A and B are mixed in the presence of the colloidal particles so that the mass concentration of the colloidal particles in the mixed solution is low from the viewpoint of increasing the silver content of the silver carbonate fine particles to be generated. More specifically, the mass concentration of colloidal particles in the mixed solution is preferably less than 10% by mass from the viewpoint of producing silver carbonate fine particles having a silver content of 15% by mass or more, and less than 5% by mass. More preferably, it is more preferably 2% by mass or less.

  As the colloidal particles, solid particles existing in a colloidal state in water are used without particular limitation. The solid particles are preferable from the viewpoint of producing silver carbonate fine particles having a high mass-based silver content as the density is small. As the solid particles, commercially available solid particles having a clear particle diameter and density, and commercially available colloidal solutions thereof can be used.

  Examples of such solid particles include metal oxide particles. The metal oxide particles include silicon oxide, aluminum oxide, zinc oxide, titanium oxide, zirconium oxide, tungsten oxide, tantalum oxide, vanadium oxide, tin oxide, copper oxide, silver Examples thereof include particles of oxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide, boron oxide, gallium oxide, yttrium oxide, germanium oxide, antimony oxide, and the like. The solid particles may be one kind of compound particles or a mixture of two or more kinds of compound particles.

  In particular, the colloidal particles are preferably silicon oxide because they are available at low cost.

  When mixing solution A and solution B in the presence of colloidal particles, the amount of carbonate ions in solution B relative to the silver ions in solution A is less than one equivalent, preventing the resulting silver carbonate fine particles from agglomerating and enlarging. From the viewpoint of The number of carbonate ions in the solution B relative to the number of silver ions in the solution A is 0.60 to 0.99 times (from the viewpoint of the control of the particle size of the silver carbonate fine particles to be produced and the mass productivity of the silver carbonate fine particles) The carbonate ion of the solution B with respect to silver ions is more preferably 0.60 to 0.99 equivalent), and further preferably 0.80 to 0.99 times.

The solution A contains silver ions and water. The solution A may further contain other components such as other ions and water-soluble organic components such as a surfactant as long as silver ions are contained. The solution A is obtained by dissolving a water-soluble silver compound in water that may contain the other components. The solution A only needs to contain a sufficient amount of silver ions to produce silver carbonate in the mixed solution, but the viewpoint of increasing the silver content and obtaining silver carbonate fine particles having a particle size of 5 μm or less. Therefore, the concentration of silver ions in the solution A is preferably 5.0 × 10 ⁻⁴ mol / L or more. The concentration of silver ions is determined from the concentration of the silver compound dissolved in the solution A. Further, it is more preferable from the viewpoint of mass production of silver carbonate fine particles that the silver ion concentration in the solution A is less than the value obtained by the above Equation 3 and the silver ion concentration in the solution A is as high as possible.

  The silver compound used in the solution A may be water-soluble, but a silver compound having high solubility is preferable in view of mass productivity of silver carbonate fine particles. Examples of such a silver compound include silver nitrate and silver fluoride. Especially, since the cost is low, the silver compound is preferably silver nitrate.

The solution B contains carbonate and water. Similarly to the solution A, the solution B may further contain other components such as other ions and water-soluble organic components such as a surfactant as long as carbonate ions are contained. Solution B is obtained by dissolving a water-soluble carbonate in water that may contain the other components. The solution B only needs to contain a sufficient amount of carbonate ions to produce silver carbonate in the mixed solution, but the viewpoint of increasing the silver content and obtaining silver carbonate fine particles having a particle size of 5 μm or less. Therefore, the concentration of carbonate ions in the solution B is preferably 2.5 × 10 ⁻⁴ mol / L or more. The concentration of carbonate ions is determined from the concentration of carbonate dissolved in the solution B.

  The carbonate used in the solution B may be water-soluble, but a compound having high solubility is preferable in view of mass productivity of silver carbonate fine particles. In addition, when the solution A and the solution B are mixed, the carbonate is a counter ion of silver ions in the solution A (for example, nitrate ions in the case of silver nitrate) and a counter ion of carbonate ions in the solution B (for example, carbonic acid). The sodium ion is preferably a compound that does not form an insoluble salt or a salt with low solubility. Examples of such a carbonate include a salt of ammonium and carbonic acid, a salt of alkali metal and carbonic acid, and a salt of alkaline earth metal and carbonic acid. The carbonate is preferably sodium hydrogen carbonate or sodium carbonate from the viewpoint of mass productivity of silver carbonate fine particles.

  More specifically, a water-soluble silver compound such as silver nitrate is used as a raw material of the solution A, and this silver nitrate is added to a commercially available colloidal solution or a diluted product thereof to obtain a colloidal aqueous solution in which silver ions are mixed as the solution A. . Further, a carbonate such as sodium hydrogen carbonate is used as a raw material of the solution B, and this carbonate is added to a commercially available colloidal solution or a diluted product thereof to obtain a colloidal aqueous solution in which carbonate ions are mixed as the solution B. Then, by mixing the obtained solution A and solution B, silver carbonate fine particles having a particle size of 5 μm or less can be obtained.

  Silver carbonate fine particles produced by mixing the solutions A and B in the presence of colloidal particles can be obtained in a state purified from the solution using a known means. For example, by separating the product obtained by the mixing from the solution by a known means such as centrifugation, and dispersing the separated product in water again and collecting it by centrifugation or the like once or more times, silver carbonate is obtained. Fine particles can be obtained.

According to the method of the present invention described above, fine carbonic acid particles having a particle size of 5 μm or less and a silver content of 15% by mass or more can be produced. In the method of the present invention, for example, the relative mixing amount of the silver ions in the solution A, the carbonate ions in the solution B, and the colloidal particles is used to determine the mass concentration of the colloidal particles in the mixed solution of the solutions A and B and the particles of the colloidal particles. Adjust and mix based on diameter. As a result, quantitative control in the mixing step is performed, but no complicated work such as temperature control or standing for curing after mixing and curing is required, so the particle size is 5 μm or less. Thus, silver carbonate fine particles suitable for antibacterial fine particles applied to a system having a high silver content of 15% by mass or more and having water can be easily and stably produced.

  The particle diameter of the obtained silver carbonate fine particles can be measured by an apparatus or method for measuring the volume average particle diameter of the particles in the liquid medium or the particles themselves. For example, a laser diffraction / scattering particle size distribution analyzer (LMS-30, Seishin company). Moreover, the obtained silver carbonate fine particles may be classified as necessary, and may be adjusted to a desired particle diameter of 5 μm or less, or two or more kinds of classified products may be newly mixed. Moreover, the silver content of the obtained silver carbonate fine particles can be measured by X-ray photoelectron spectroscopy.

  According to the present invention, the particle size is 5 μm or less and the silver content is 15% by mass or more by appropriately adjusting within the range of conditions defined in the present invention according to the type of silver carbonate fine particles to be generated. Silver carbonate fine particles can be produced.

In the present invention, as the colloidal particles, silicon oxide having a solid density of 2.5 g / cm ³ or less and a particle size of about 5 to 25 nm or a commercially available colloidal solution thereof is used. Is particularly preferable from the viewpoint of practicality in the production of silver carbonate fine particles and usefulness as antibacterial agent fine particles.

  The antibacterial resin film coating material of the present invention contains silver carbonate fine particles having a particle size of 5 μm or less and a silver content of 15% by mass or more and a resin. As the silver carbonate fine particles, the silver carbonate fine particles produced by the method of the present invention described above can be used. The antibacterial resin film paint of the present invention can be produced by using the silver carbonate fine particles produced by the above-described method of the present invention in accordance with an ordinary antibacterial paint production method in which the resin is dispersed.

  Content of the said silver carbonate microparticles | fine-particles is 14-88 mass% (10-61 mass% in the silver content rate of a film | membrane) in the antibacterial resin film by the said coating material. With such a content, the coating material of the present invention forms a sufficiently strong film when applied to a surface where water is present, and exhibits antibacterial properties over a long period of time. The paint having such a content is prepared by, for example, mixing and preparing the silver carbonate fine particles in the present invention at a mass of 0.16 to 7.33 times that of the resin in a paint composed of only silver carbonate fine particles and a resin. can get. In the paint of the present invention, the content of the silver carbonate fine particles in the antibacterial resin film is 51.0 to 77.5% by mass (29 to 54% by mass in terms of silver content of the film). It is more preferable from the viewpoint of forming a sufficiently strong film when the paint of the present invention is applied to the existing surface and exhibiting antibacterial properties over a long period of time. In addition, content of the silver carbonate fine particle in the said film | membrane can be calculated | required as content of the silver carbonate fine particle with respect to the total weight of the said resin and silver carbonate fine particle in the coating material of this invention.

  As the resin, a resin used for an antibacterial paint containing inorganic antibacterial fine particles can be used. Such resins include thermoplastic resins and thermosetting resins. Examples of the thermoplastic resin include acrylic acid ester, methacrylic acid ester, polyethylene, polypropylene, polyamide, polymethyl methacrylate, acrylonitrile-butadiene-styrene resin, and polyester. Examples of the thermosetting resin include an epoxy resin, a phenol resin, a melamine resin, and an unsaturated polyester resin.

  The resin can be used alone or as a polymer blend in which two or more kinds are combined. That the resin is an aqueous resin such as an aqueous epoxy-modified alkyd resin from the viewpoint of reducing consideration for the work environment (for example, maintenance of the work environment and cost for the work) when applying the paint of the present invention. preferable.

In the paint of the present invention, other components than the above-mentioned silver carbonate fine particles and resin can be blended within a range that does not affect the antibacterial action of the silver carbonate fine particles. Examples of such other components include antibacterial agents other than the above-described silver carbonate fine particles, and solvents.

  The paint of the present invention can be used on the surface of a member in which water is present (more preferably, water flows). As described above, since silver carbonate has the property of being discolored by exposure to light, it is preferable to apply the coating material of the present invention to a portion where such a change in appearance does not cause a problem.

  The antibacterial heat exchanger of the present invention has a heat exchange part for heating or cooling a fluid and an antibacterial resin film formed on the surface of the heat exchange part, and the surface of the heat exchange part during heat exchange This is a heat exchanger in which water is present. The antibacterial resin film is an antibacterial resin film formed by applying the above-described paint of the present invention.

  The antibacterial resin film preferably has a thickness of 2 μm or more from the viewpoint of exhibiting antibacterial properties over a long period of time, and preferably 10 μm or less from the viewpoint of realizing higher heat transfer efficiency in the heat exchange section. Further, it is preferably 5 μm or less from the viewpoint of cost.

  The heat exchange part is not particularly limited, but preferably has a large surface area. Examples of such a heat exchange part include plate fins.

  The antibacterial heat exchanger of the present invention exhibits an antibacterial action in a state where water is present on the surface of the heat exchange part. The antibacterial heat exchanger of the present invention is used in a mode including a mode for heating and cooling water as a fluid and a mode for cooling a gas containing moisture such as outside air. The antibacterial heat exchanger of the present invention is suitably used for a heat exchanger for air conditioning, more specifically, a heat exchanger used for an indoor unit of an air conditioner.

  In the present invention, if the amount of water in contact with the heat exchanging part, such as the amount of condensed water generated from the heat exchanger, is known, by adjusting the antibacterial silver carbonate fine particle content and film thickness in the paint, for example, It is possible to design the antibacterial performance lifetime based on the test results of the accelerated test.

<Example 1> Formation of silver carbonate fine particles A silicon oxide sol having a density of 1.21 g / cm ³ and containing silicon oxide 2 having a particle diameter of 16 nm and a density of 2.65 g / cm ³ as a colloid (trade name: CATALOID S A colloidal aqueous solution containing 0.3 mass% of -30H, manufactured by Catalyst Chemical Industry Co., Ltd. in water was prepared. 24 g of silver nitrate was added to 1 L of the obtained colloidal aqueous solution to prepare a solution A. Further, 11.5 g of sodium hydrogen carbonate (about 0.97 equivalent to silver of the solution A) was added to 1 L of the aqueous colloidal solution to prepare a solution B. Next, the solution A and the solution B were mixed and stirred to produce silver carbonate fine particles in the AB mixed solution. In addition, the ratio of the number of silver atoms, which is the sum of the number of silver ions and the number of silver atoms that are not ions, to the number of colloidal particles in the AB mixed solution is 7.0 × 10 ⁴ . When the obtained silver carbonate fine particles were observed with a microscope, they were silver carbonate fine particles having a particle size of 5 μm or less. At this time, the silver content in the silver carbonate fine particles is 56%.

<Example 2> Silver carbonate fine particles Next, by changing the particle size of the colloid, the mass concentration of the silicon oxide sol contained in the aqueous colloid solution, the ratio of the number of silver atoms to the number of colloid particles, and the type of carbonate, Solutions A and B were prepared and mixed in the same manner as in Example 1, and an AB mixed solution was obtained to produce silver carbonate fine particles. The state of the fine silver carbonate particles or the states of the solutions A and B are shown in Table 1, the ratio of the number of silver atoms to the number of colloidal particles in the AB mixed solution at that time is shown in Table 2, and the colloidal particles in the AB mixed solution The number concentrations are shown in Table 3, respectively. For silicon oxides 1, 3, and 4 in the table, silicon oxide sols containing these silicon oxides (both silicon oxides had a density of 2.65 g / cm ³ ) were used. For silicon oxide 1, use “FINE CATALOID F-120”; for silicon oxide 3, use “CATALOID SI-50”; and for silicon oxide 4, use “CATALOID SI-45P” (trade names, manufactured by Catalyst Kasei Kogyo Co., Ltd.) It was.

In Table 1, ○ indicates that silver carbonate fine particles having a particle size of 5 μm or less were formed satisfactorily, × indicates that silver carbonate was formed as giant particles and did not have a particle size of 5 μm or less, and xx indicates a solution. It shows that A or solution B was gelled and solidified and silver carbonate fine particles were not obtained. The results of Example 1 are shown in Table 1 in the intersecting mass of rows of NaHCO ₃ in silicon oxide 2 and columns of colloidal particle mass concentration of 0.3% by mass.

Solutions A and B are prepared using a colloidal solution containing colloidal particles having a particle diameter of 45 nm or less, and in the AB mixed solution after mixing of solutions A and B, the colloidal particles have a mass concentration of 10% by mass or less, and The ratio of the number of silver atoms to the number of colloidal particles in the AB mixed solution (the sum of the number of silver ions and the number of non-ionized silver atoms in the AB mixed solution) is 2.7 × 10 ⁵ or less. It was confirmed that silver carbonate fine particles having a particle size of 5 μm or less were produced satisfactorily. Further, it was confirmed that silver carbonate fine particles having a particle diameter of 5 μm or less could not be obtained well when the mass concentration of colloidal particles and the ratio of the number of silver atoms to the number of colloidal particles were out of the above ranges.

  Further, for each of the lower limit and the upper limit of the range in which silver carbonate fine particles having a particle diameter of 5 μm or less in Table 3 were obtained, the reciprocal (1 / x) of the particle diameter x of the colloid particles and the AB mixed solution at that time The relationship with the colloidal particle number concentration was expressed by a power approximation formula. If the lower limit value or the upper limit value of four points is not applied to the obtained power approximation formula, the solution A and B colloidal particle mass concentration is in the range of 0.1 to 1.0% by mass, 2 to 3 points. A power approximation formula was selected.

More specifically, four points of the lower limit value of the above range in Table 3, that is, the number concentration of colloidal particles when x is 6 is 3.9 × 10 ¹⁵ (the mass concentration of colloidal particles of solutions A and B is 0.1). Point 1 where x is 16 and the number concentration of colloidal particles at 16 is 6.1 × 10 ¹⁴ (the mass concentration of colloidal particles of solutions A and B is 0.3% by mass). The colloidal particle number concentration is 3.3 × 10 ¹⁴ (the mass concentration of the colloidal particles in solutions A and B is 0.7% by mass), and the colloidal particle number concentration when x is 45 is 1.9 × 10 ^14. The power approximation formula was determined from the four points of point 4, which is (the mass concentration of the colloidal particles of the solutions A and B is 2% by mass). Among the four points, the point 3 deviating from the obtained power approximation formula and The power approximation formula is further calculated from the two points 1 and 2, excluding the two points 4. Determined, the formula 1) was obtained.

Further, four points of the upper limit value in the above range in Table 3, that is, the point 5 where the colloidal particle number concentration is 4.3 × 10 ¹⁷ when x is 6, and the colloidal particle number concentration when x is 16 is 2.3 × 10. Point 6, which is ¹⁶ ; point 7 where the colloidal particle number concentration is 5.3 × 10 ¹⁵ when x is 26; and point 8 where the colloidal particle number concentration when x is 45 is 1.0 × 10 ¹⁵ (both solutions) The power approximation formula was obtained from the four points of the mass concentration of colloidal particles A and B of 10% by mass, and the above formula 2) was obtained.

Furthermore, regarding the lower limit of the range in which silver carbonate fine particles having a particle size of 5 μm or less in Table 2 were obtained, the particle diameter x of the colloidal particles and the ratio of the number of silver atoms to the number of colloidal particles in the AB mixed solution at that time The relationship was expressed by a polynomial approximation. More specifically, in Table 2, the number of silver atoms with respect to the number of colloidal particles in the AB mixed solution in which four points are smaller than the lower limit value of the range and closest to the lower limit value, that is, x is 6 is 2. The number of silver atoms with respect to the number of colloidal particles in the AB mixed solution at point 9 where x is 16 is 2 × 10 ⁴ (the mass concentration of colloidal particles in solutions A and B is 0.05 mass%) is 2.1 × 10 ⁵ (the mass concentration of colloidal particles in solutions A and B is 0.1% by mass), the number of silver atoms is 1.8 × 10 ⁵ (solution) with respect to the number of colloidal particles in the AB mixed solution in which x is 26 and x is 26 The number of silver atoms with respect to the number of colloidal particles in the AB mixed solution at point 11 where the mass concentration of colloidal particles of A and B is 0.5% by mass, and x is 45 is 4.6 × 10 ⁵ (solution A and The mass concentration of B colloidal particles is 1 When the polynomial approximate expression is obtained from the four points of the point 12, which is 0 mass%), among the four points, the points 9, 11 and 12 except for one point 10 deviating from the obtained polynomial approximate expression are obtained. A polynomial approximate expression was further obtained from the three points to obtain the above expression 3).

<Example 3> Silver carbonate antibacterial paint and heat exchanger The epoxy-modified alkyd resin as a resin material and the silver carbonate fine particles prepared in Example 1 were solidified with silver carbonate fine particles based on the solid content weight 1 of the resin material. A silver carbonate antibacterial paint was prepared by kneading at a weight ratio of 1.2.

  This paint was uniformly applied to the front and back surfaces of the plate fin material of the heat exchanger with a thickness of 3 μm by a roll coater to produce an antibacterial heat exchanger. At this time, the silver carbonate content in the coating film is 54.6% by mass (silver content: 30.6% by mass).

  Using a fan coil unit using this antibacterial heat exchanger and a commercially available fan coil unit with a normal heat exchanger with acrylic resin applied to the fin surface as a comparative test, sucking in outside air while humidifying it, dehumidifying operation For 1 year. The elution concentration of silver ions in the condensed water and the number of adherent bacteria on the surface of the plate fin of the heat exchanger were measured at regular intervals. The test results are shown in Table 4.

  The silver ion concentration in the condensed water of the antibacterial heat exchanger was always 50 ppb or more throughout the test period, and the number of surface-attached bacteria was always 1/100 or less compared to the normal heat exchanger. The antibacterial effect of this antibacterial heat exchanger was confirmed.

Next, using one plate fin (surface area 228 cm ² ) coated with the silver carbonate antibacterial paint, an accelerated test for confirming the silver elution amount was performed by the following method.

  An accelerated deterioration confirmation test for elution of silver ions was conducted for 250 days under the condition that high-temperature water (about 80 ° C.) always flows on the plate fin surface at a flow rate of 25 mL / min. The acceleration coefficient at this time is about 11 times that in the case of a normal condensed water temperature of 15 ° C. This test period corresponds to a period of about 15 and a half years, assuming that condensed water occurs 24 hours a day, 6 months within a year. High temperature water was sampled at regular intervals, and the silver ion elution concentration was measured. Table 5 shows the results of the dissolution acceleration test.

  During the acceleration test, it was confirmed that silver ions were eluted from the plate fin at 50 ppb or more. From this, when the antibacterial heat exchanger is operated under normal conditions with a condensed water generation period of 6 months, it is estimated that silver ions of 50 ppb or more are eluted into the condensed water for a period of about 15 years and a half. .

Claims (18)

In a method for producing silver carbonate fine particles by mixing a solution A containing silver ions and a solution B containing carbonate ions in the presence of colloidal particles,
The particle diameter of the colloidal particles is x [nm], the particle number concentration with respect to the solvent mass of the colloidal particles in the mixed solution in which the solution A and the solution B are mixed is y [number / g], and the number of colloidal particles in the mixed solution. When the ratio of the number of silver atoms to z is z, the particle number concentration y of the colloidal particles is not less than the value obtained by the following formula 1 and not more than the value obtained by the following formula 2, and the ratio of the number of silver atoms A method comprising mixing solutions A and B in the presence of colloidal particles so that z is less than a value obtained by the following formula 3.
Formula 1) y = 1.16 × 10 ¹⁷ × (1 / x) ^1.9
Formula 2) y = 9.23 × 10 ¹⁹ × (1 / x) ^3.0
Formula 3) z = k * (175.3x < ² > + 2196.3x + 2793)
(In Formula 3, k is 1.)   The method according to claim 1, wherein the mass concentration of colloidal particles in the mixed solution is less than 5 mass%.   The method according to claim 1 or 2, wherein the colloidal particles have a particle diameter of less than 50 nm.   The method according to claim 1, wherein the colloidal particles are silicon oxide.   The method according to claim 1, wherein the carbonate ion of the solution B with respect to silver ions of the solution A is less than 1 equivalent.   The method according to claim 1, wherein the solution A is an aqueous solution of silver nitrate.   The method according to any one of claims 1 to 6, wherein the solution B is an aqueous solution of sodium hydrogen carbonate or sodium carbonate.   A coating material for an antibacterial resin film containing silver carbonate fine particles having a particle size of 5 μm or less and a silver content of 15% by mass or more, and a resin, wherein the content of the silver carbonate fine particles is the antibacterial resin The coating material for antibacterial resin films which is 14-88 mass% in a film | membrane.   The antibacterial resin film paint according to claim 8, wherein the silver carbonate fine particles are produced by the method according to claim 1.   The antibacterial resin film paint according to claim 8 or 9, wherein the content of silver carbonate fine particles in the antibacterial resin film is 51.0 to 77.5 mass%.   The said resin is a thermoplastic resin or a thermosetting resin, The coating material for antibacterial resin films as described in any one of Claims 8-10 characterized by the above-mentioned.   The thermoplastic resin is one or more selected from the group consisting of acrylic acid ester, methacrylic acid ester, polyethylene, polypropylene, polyamide, polymethyl methacrylate, acrylonitrile-butadiene-styrene resin, and polyester. The antibacterial resin film paint according to claim 11.   12. The antibacterial resin film paint according to claim 11, wherein the thermosetting resin is one or more selected from the group consisting of an epoxy resin, a phenol resin, a melamine resin, and an unsaturated polyester resin. .   The antibacterial resin film paint according to claim 13, wherein the resin is an aqueous epoxy-modified alkyd resin. In a heat exchanger having a heat exchange part for heating or cooling a fluid and an antibacterial resin film formed on the surface of the heat exchange part, and water is present on the surface of the heat exchange part during heat exchange ,
The antibacterial resin film is an antibacterial resin film formed by applying the antibacterial resin film paint according to any one of claims 8 to 14.   The antibacterial heat exchanger according to claim 15, wherein the antibacterial resin film has a thickness of 10 μm or less.   The antibacterial heat exchanger according to claim 16, wherein the antibacterial resin film has a thickness of 5 μm or less.   The antibacterial heat exchanger according to any one of claims 15 to 17, wherein the heat exchange part is a plate fin for cooling a gas.