JPH04131111A - Preparation of sterilization filter medium - Google Patents

Abstract

PURPOSE:To obtain sufficient sterilization effect as a conventional way with a smaller sterilization filter medium than a conventional one by applying a mixture prepared by mixing a silver chloride power and an organic vehicle to a substrate, and heating the substrate to carry the silver chloride on the substrate. CONSTITUTION:A silver chloride and an organic vehicle containing at least an alcohol-based oil and maleic acid-based resin are mixed in a weight ratio of 1 silver chloride against <=1.5 (excluding 0) organic vehicle. The obtained mixture is applied to a substrate (e. g. porous ceramics and the substrate is heated to carry the silver chloride on the substrate. As a result, the silver chloride is held three-dimensionally in the porous ceramics so that contact surface area of the silver chloride and hot water is increased and sterilization effect as sufficient as a conventional way is achieved even if the sterilization filter medium is smaller than a conventional one. Also, since the adhesion strength is heightened, not like the conventional way, a silver chloride film is not dropped by an impact.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a sterilizing filter medium used in bath circulating water heaters and the like.

Conventional technology In recent years, demand for circulating water heaters for baths has been increasing.

FIG. 2 is a schematic diagram showing a general bath circulation water heater.

In FIG. 2, 1 is a bathtub, and the bathtub 1 is provided with a water discharge pipe 2 and a water intake pipe 3, respectively. 4 is a filter provided in the water suction pipe 3, and the filter 2 filters out large particles such as hair.

5 is a pump for circulating hot water, and 6 is a filtration device that filters fine dust from the hot water sent from the pump 5 and sterilizes it. Hot water in the bathtub 1 is sent to a filter device 6 by a pump 5, filtered and sterilized, and returned to the bathtub through the water discharge pipe 2. Conventionally, this filtration device 6 has zeolite, activated carbon, etc. sealed therein to adsorb bacteria, and bacteria have been killed by ozone, ultraviolet rays, or chlorine inside the filtration device 6 to sterilize hot water. However, there is concern that sterilization using ozone or chlorine may leave residues in hot water and have an adverse effect on the human body. Furthermore, sterilization by adsorption of bacteria to zeolite or activated carbon and irradiation with ultraviolet rays does not exhibit any sterilization effect if the circulation of hot water is stopped.

As a countermeasure against this problem, in recent years metals with bactericidal properties (such as silver) have been
A method has been developed to suppress the growth of bacteria by eluting it into warm water. When this method is used, the metal ions eluted into the hot water exhibit a bactericidal effect even when the operation of the bath circulation water heater is stopped, preventing the generation of scale and bad odors. Conventionally, a mixture of a binder and silver chloride powder was applied to a filter medium to form a silver chloride layer on the filter medium, and the filter medium was placed in a filtration device to elute silver into hot water. It was being sterilized.

Problems to be Solved by the Invention However, in the conventional configuration, the binder and silver chloride powder are mixed and applied to the filter medium to form a silver chloride layer, so the silver chloride powder is coated on the binder. Therefore, only the silver chloride on the surface of the silver chloride layer is eluted into the hot water. Therefore, the efficiency is extremely low, and in order to maintain the silver concentration in hot water at a predetermined value, it is necessary to provide a silver chloride layer on a large filter medium, resulting in a large filtration device. Furthermore, since the bonding strength between the silver chloride layer and the filter medium was not very strong, the silver chloride layer would fall off if the filter medium was subjected to impact, so there was a problem in that the filter medium had to be handled carefully. .

The present invention solves the above-mentioned conventional problems, and aims to provide a method for producing a sterilizing filter medium that can obtain a predetermined silver concentration even if the filter medium is small, and in which silver chloride is difficult to fall off from the filter medium. There is.

Means for Solving the Problem To achieve this objective, silver chloride powder is mixed with an organic vehicle consisting of at least an alcohol-based oil and a maleic acid-based resin, the mixture is applied to a substrate, and the substrate is then heat-treated. was applied.

Function: With this configuration, silver chloride can be held three-dimensionally within the porous ceramic.

EXAMPLE A method for producing a sterilizing filter medium according to an example of the present invention will be described below.

First, as an organic vehicle, squeegee oil (alcohol maleic, manufactured by Toka Shiki Kagaku Kogyo Co., Ltd.), which is a mixture of alcohol oil and maleic acid resin, and silver chloride powder (
Made by Nichi Kikinzoku Co., Ltd. Particle size: 75 μm or less) by weight
: Blend in a ratio of 1:1 and mix using an agitator to create a coating agent. Next, as shown in FIG. 1(a), a frame 8 is erected on the periphery of the substrate 7 made of porous ceramic (alumina-silica type, pore diameter 100 μm, manufactured by Iwaya Porcelain Industry Co., Ltd.), and the frame 8 surrounds the substrate 7. A coating agent is poured onto the surface of the substrate 7. Then, dry at room temperature for 10 to 60 minutes, as shown in Figure 1(b).
A coating layer 9 is formed as shown in FIG.

During this drying process, the coating agent permeates into the substrate 7. After drying, the substrate 7 is heated by a heating means such as a furnace.
Heat treatment is performed at a temperature of 00°C to 600°C for about 30 minutes. As a result of this heat treatment, the squeegee oil contained in the coating layer 9 is almost completely decomposed into water and carbon dioxide gas, as shown in Figure 1 (
A silver chloride layer 10 is formed as shown in C). The reason why alcohol maleic acid was used as the organic vehicle was to prevent silver chloride from being reduced and turned into silver during heat treatment.

In the sterilizing filter media formed in this way, the silver chloride enters the many pores of the porous ceramic and is held three-dimensionally, so unlike conventional sterilizing filter media, the silver chloride film does not fall off due to impact etc. . Furthermore, since the contact area between silver chloride and dry water becomes very large, even a small sterilizing filter medium can sufficiently increase the silver concentration in hot water. As described above, since the sterilizing filter medium of this embodiment can be made small in size, when used in the bath circulation water heater shown in FIG. 2, the filtration device can be made compact.

The effects of this embodiment will be explained below with specific examples.

(Example 1) The sterilizing filter medium described in the above method, that is, in FIGS. 1(a), (b), and (c), was housed in the filtration device 6 shown in FIG. 2.

(Comparative example 1) An ultraviolet germicidal lamp was installed in the filter device θ shown in FIG.

(Comparative Example 2) A sterilizing filter medium was prepared by coating a porous ceramic plate with polystyrene, spraying silver chloride powder thereon, and drying it. This sterilizing filter medium was installed in a filter device 6 shown in FIG.

In the first test, bacteria were mixed into the hot water in the bathtub 1 shown in Figure 2, and the hot water was circulated at 40°C for 1000 hours to determine the number of bacteria in the hot water (general bacteria test: ordinary agar medium). ) and the time-dependent change in the detected amount of silver was examined using an atomic absorption spectrophotometer (Jarrell AshAA-860, Japan). The results are shown in Table 1.

(Margin below) Table 1 (Margin below) As can be seen from Table 1, in Example 1, no bacteria could be detected 4 hours after circulating hot water. Further, in Comparative Example 1 using an ultraviolet lamp, no bacteria could be detected after 2 hours. Moreover, in Comparative Example 2, no bacteria could be detected after 500 hours. This first experiment shows that both Example 1 and Comparative Example 1 exhibit bactericidal action. Furthermore, in Comparative Example 2, it is thought that because the silver chloride was coated with polystyrene, it took a longer time to exhibit the bactericidal effect than in the other examples.

In a second experiment, hot water was circulated at 40°C for 24 hours, then the circulation of hot water was stopped, and the number of bacteria and silver concentration in the hot water were examined over time in the same manner as in the first experiment. The results are shown in Table 2.

(Margins below) Table 2 (Margins below) As can be seen from Table 2, in Comparative Example 1, when the hot water circulation was stopped, bacteria began to grow again. This means that in the case of sterilization using ultraviolet rays, it is necessary to constantly circulate hot water and expose the hot water to ultraviolet rays. In other cases, the silver was dissolved in the hot water, so there was no bacterial growth. However, it can be seen that in Comparative Example 2, it takes much longer to exhibit the bactericidal effect than in Example 1.

Next, as a third experiment, 30 cm2 of the sterilizing filter media prepared in Example 1 and Comparative Example 2 were each immersed in 1 liter of tap water (chloride ion concentration: 10 ppm) at 40°C.
The silver concentration was measured after 24 hours had elapsed. This is 132
Measurements were made up to 0 hours, and the results are summarized in Table 3.

(Margin below) Table 3 (Margin below) As can be seen from Table 3, in Comparative Example 2, the silver chloride concentration was 0.
．． O exceeds 7ppm after 720 hours, but in Example 1 it is already 0.0 after 24 hours. O exceeds 7ppm. As can be seen from this experiment, in Example 1, the contact area between the silver chloride layer and water was extremely large.

These experiments show that the sterilizing filter medium of this example exhibits a sterilizing effect very quickly.

Next, the mixing ratio of the alcohol maleic acid-based organic vehicle and the silver chloride powder will be explained.

As a fourth experiment, multiple samples were prepared by mixing an alcohol-maleic acid-based organic vehicle in a weight ratio of 0 to 3 with respect to the proportion of silver chloride powder, and the samples were heat-treated. The ratio of silver to silver chloride was determined.

(Hereafter the margin) Table 4 (Hereafter the margin) As can be seen from Table 4, when the ratio of the organic vehicle becomes 1.5 or more, the ratio of silver chloride decomposing into silver and chlorine increases rapidly. Therefore, the mixing ratio of the organic vehicle is silver chloride]
When the ratio is 1.5 or less, silver chloride can be more efficiently supported on the substrate.

As described above, in this example, a coating agent is formed by mixing an alcohol-maleic acid-based organic vehicle and silver chloride, and the coating agent is applied to a substrate made of porous ceramics, dried, and heat-treated. As a result, the filter material does not fall off even if a shock is applied to it like in the past, so the sterilization effect lasts for a long time.

Furthermore, since the contact area between silver chloride and hot water is increased, the same sterilizing effect can be obtained even with a smaller sterilizing filter medium than before.

Although warm water was used in this embodiment, the same effect can be obtained with water at room temperature or cold water.

Effects of the Invention The present invention mixes silver chloride powder and an organic vehicle consisting of at least alcoholic oil and maleic acid resin,
By applying the mixture to the substrate and then heat-treating the substrate, silver chloride can be held three-dimensionally within the porous ceramic, increasing the contact area between hot water and silver chloride. Even with a smaller sterilizing filter medium than before, it is possible to obtain the same sterilizing effect as before. Furthermore, since the bonding strength is increased, the silver chloride film does not fall off due to impact as in the conventional method.

[Brief Description of the Drawings] Figure 1 (a), (b), and (c) are process diagrams showing a method for manufacturing a sterilizing filter medium in an embodiment of the present invention, and Figure 2 shows a general circulating water heater for baths. It is a schematic diagram. 7... Board 8... Frame 9...
... Coating layer 10 ... Silver chloride layer

Claims (3)

[Claims] (1) Mixing silver chloride powder with an organic vehicle consisting of at least alcohol-based oil and maleic acid-based resin, applying the mixture to a substrate, and then heat-treating the substrate to support silver chloride on the substrate. A method for producing a sterilizing filter medium, which is characterized by: (2) The method for producing a sterilizing filter medium according to claim 1, wherein the substrate is made of porous ceramic or inorganic fiber. (3) A method for producing a sterilizing filter medium, characterized in that an organic vehicle is mixed in a weight ratio of 1 part silver chloride to 1.5 or less (excluding 0) of an organic vehicle.