JPH07165521A - Antibacterial sand and its production - Google Patents

Abstract

PURPOSE:To obtain hygienic sand suitable for the use in a sandbox of kindergar ten, school, park, etc., and the sand of golf links, race track, etc. CONSTITUTION:This antibacterial sand is produced by coating the surface of sand with an antibacterial agent containing silver or copper through a binder composed of one or more substances selected from phenol resin, silicone, acrylic emulsion, vinyl acetate, rubber emulsion, urethane and liquid paraffin. The antibacterial sand can be produced by heating natural sand or artificial sand generated by quarrying at a proper temperature between 100 and 500 deg.C, adding an antibacterial agent containing silver or copper together with a binder to the heated sand and kneading the mixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sanitary sand suitable for use in sand fields such as kindergartens, schools, parks, golf courses, horse racetracks, tennis courts of artificial turf, etc. Is.

[0002]

2. Description of the Related Art Sandboxes such as kindergartens, schools, and parks are suitable playgrounds for children, but due to recent pet booms, they have become places for defecation and urination of dogs, cats, etc. It breeds and causes fever and eye irritation in infants. In order to prevent this, a technique of mixing ceramic particles containing an antibacterial agent with sand has been proposed, but sufficient effects have not been obtained.

[0003]

Therefore, measures are taken such as putting a net in the sandbox when not in use to prevent dogs, cats, etc. from entering, but extra equipment and materials are required. At the same time, since it requires complicated work, it is currently rarely performed. Therefore, an object of the present invention is to prevent the propagation of pathogenic bacteria and the like by imparting antibacterial properties to the sand itself such as a sandbox.

[0004]

In order to solve the above problems, the present invention employs the following configurations. That is, the antibacterial sand according to the present invention is an antibacterial agent containing silver or copper, and one or more kinds of the binder group consisting of phenol resin, silicon, acrylic emulsion, vinyl acetate, rubber emulsion, urethane, and liquid paraffin. It is characterized by coating the surface of sand with a binder consisting of.

The method for producing antibacterial sand according to the present invention comprises a step of heating sand at an appropriate temperature within a range of 100 to 500 ° C.
The method is characterized by including a step of adding an antibacterial agent containing silver or copper and a binder to the heated sand and kneading.

A detailed example will be described below.
The sand used in the present invention is natural or artificial sand such as crushed stone, for example, silica sand, river sand, mountain sand, crushed sand and the like.
The antibacterial agents include inorganic antibacterial agents and organic antibacterial agents. Inorganic antibacterial agents are known to have antibacterial properties such as Hg, Ag,
Metals such as Pb, Cu, Ni, Zn, and Cd are held on an inorganic carrier, and the inorganic carrier is an inorganic ion exchanger, a porous body, or the like. Specifically, zeolite, apatite, Activated carbon etc. As the antibacterial metal, silver (Ag) is preferably used, and examples thereof include zirconium phosphate silver, zeolite silver, and apatite silver. On the other hand, as the organic antibacterial agent, there is an organic substance containing the antibacterial metal.

As the binder, a phenol resin is preferably used, but in addition to this, silicone, acrylic emulsion, vinyl acetate, rubber emulsion, urethane resin, liquid paraffin and the like can be used.

1 and 2 show the manufacturing process of the present invention.
Two slightly different examples are illustrated. First, the compounding ratio of an antibacterial agent (inorganic antibacterial agent in this example), a binder and the like to sand as a raw material, for example, silica sand, is calculated. The preferred compounding ratio is, by weight ratio, 0.3 to 3.5 parts of resin (binder such as rubber or acrylic) and 0.01 to 100 parts of sand to 100 parts of sand.
It is one copy. A predetermined amount of sand is put in a feed hopper and the sand is heated. The heating temperature is usually preferably 100 to 500 ° C. Sufficient heating of the sand kills bacteria and helps the binder to coat the surface of the sand.

The heated sand, the antibacterial agent and the binder are kneaded by using a kneader. As a kneading machine, a peripheral speed of 100 to 600 m / min is more preferable in a pot for putting raw materials, and 2 is preferable.
It is preferable to use a kneader equipped with blades rotating at a high speed of 00 to 300 m / min, for example, a screw beater, but other suitable kneaders may be used. The kneaded mixture is discharged from the mixer, cooled, and sieved if necessary to remove lumps and foreign substances.

In the sand thus obtained, the surface of the sand body is coated with an antibacterial agent with a binder, so that the growth of Escherichia coli, Staphylococcus aureus, Bacillus subtilis, molds, moss, algae, etc. is prevented. . Therefore, when used in a sandbox at a school or the like, it is possible to prevent contamination by various bacteria. When an inorganic antibacterial agent is used as the antibacterial agent coated on sand, it is more durable than an organic antibacterial agent, effective against a wide range of bacterial species, and less likely to cause resistance. Further, since it has heat resistance, it is stable and highly safe, and since it does not volatilize or evaporate in the air, it can be used semipermanently. On the other hand, when an organic antibacterial agent is used as the antibacterial agent, the immediate effect is excellent, but the effect is different depending on the bacterial species and resistance is likely to occur. In addition, volatile decomposition is likely to occur, and safety is relatively low.

The thickness of the coating layer, that is, the film thickness containing the antibacterial agent is preferably 0.3 to 15 μm. For example, if this film thickness is increased, a cushioning effect can be expected on the sand surface. If it can be made thin, the feel of the sand itself can be maintained. Further, when rubber emulsion or liquid paraffin is used as the binder, the fluidity of the obtained antibacterial sand is lowered, so that the outflow of sand can be prevented when it is used in a dirt course, a tennis court, etc. of a racetrack.

[0012]

[Example] The antibacterial sand of the present invention was produced using a speed mixer used for kneading foundry sand. The sand used was silica sand from Aomori and China. Novalon (trade name) from Toagosei Co., Ltd. as an inorganic antibacterial agent and Amorden (trade name) from Daiwa Chemical Co., Ltd. was used as an organic antibacterial agent. Further, as the binder, phenol, neoprene rubber (Showa Denko Dyupon), acrylic (AT-2040) (Showa High Polymer), vinyl acetate (S-61) (Showa High Polymer), silicone (AY43-021) (Toray) (Silicone 50%, Methanol 50%) was used, and methanol and water were used as these diluents.

The manufacturing conditions were the following two types (a) and (b). In the step (a), 15 kg of sand at a predetermined temperature was put into a speed mixer (a kind of high-speed rotary kneader), and immediately after that, a binder mixed with an antibacterial agent was put thereinto, and the lid was closed and kneading was performed for 60 seconds. After opening the lid, the diluent was exhaled while kneading. This time was set to 80 seconds in the case of diluting with methano and 150 seconds in the case of diluting with H ₂ O. In the case of methanol dilution, the target sand temperature was 120 ° C, and in the case of H ₂ O dilution, the target sand temperature was 150 ° C.

On the other hand, in the step (b), 15 kg of sand having a predetermined temperature was put into a speed mixer, an antibacterial agent was put therein, the lid was closed, and the mixture was kneaded for 10 seconds. Immediately thereafter, the binder was added, the lid was closed, and the mixture was kneaded for 60 seconds. After the lid was opened, the diluent was released while kneading. This time was 80 seconds when diluted with methanol and 150 seconds when diluted with H ₂ O. When diluting with methanol, set the target sand temperature to 120 ° C and add H ₂
In the case of O dilution, the target sand temperature was 150 ° C.

As a binder, phenol (M
S380) 75 g + methanol 400 g were diluted so that the phenol content was 10% by weight. Since silicon (AY43-021) is a 50% methanol diluted solution, 150 g of the stock solution was diluted with 325 g of methanol.
When using other resins as binders, H ₂ O
It was diluted to 200 g in consideration of drying conditions and the like.

The particle size distribution of the sand used was as shown in Table 1 and the production conditions were as shown in Table 2.

[0017]

[Table 1]

[0018]

[Table 2]

When the appearance, feel, antibacterial property, etc. of the antibacterial sand produced under the above conditions were examined, it was found that the appearance and feel were comparable to those of ordinary sand, and the antibacterial property was also excellent. Further, when the coating state of the coating layer containing the antibacterial agent was examined by an electron microscope, it was found that the coating layers were in a very good state.

Further, antibacterial sand was produced under the conditions shown in Table 3 and its antibacterial property was tested by the shake flask method (JIS). The test method uses an inorganic antibacterial agent "Novalon" as an antibacterial agent (Sample Nos. 1, 2, 5, 6, 9,
11 and 14), 2 g of each sample was taken, placed in 15 ml of a phosphate buffer solution, further added with Staphylococcus aureus and shaken at 27 ° C. for 1 hour, and the number of surviving bacteria was measured thereafter. As a result, the initial number of bacteria was 2.5 × 10 ⁵ , while the number of surviving bacteria after shaking was less than 10. In addition, without adding any of the above samples, Staphylococcus aureus was added to 15 ml of a phosphate buffer solution, and the mixture was shaken at 27 ° C. for 1 hour, and the number of surviving cells was measured. The result was that the number of surviving cells was 3.5 × 10 ^4. Met.

[0021]

[Table 3]

The test using the organic antibacterial agent "Amorden" as the antibacterial agent was conducted under the following conditions.
First, about 15 ml of agar medium for bacteria was poured into a sterile petri dish. Approximately 5 m of agar medium containing the bacterial solution of the test bacteria after solidification
The cells were overlaid with a lid, covered with a lid, and cultured at 37 ° C. for 24 hours, and the presence or absence of antibacterial effect was observed. Escherichia coli, staphylococcus and Bacillus subtilis were used as test bacteria. The test results are shown in Table 4.

[0023]

[Table 4]

[0024]

As is apparent from the above description, according to the present invention, unlike the conventional antibacterial sand, the surface of the sand itself is coated with the antibacterial agent, so that the sand itself has antibacterial properties. However, bacterial growth has come to be effectively suppressed. Since the antibacterial agent is coated with the binder, the adhesive strength is high and the effect lasts for a long time. For this reason,
It is hygienic when used as sand that is easily touched by humans, such as sand from sandboxes and sand from golf courses.

[Brief description of drawings]

FIG. 1 is a process chart illustrating a manufacturing process of the present invention.

FIG. 2 is a process chart illustrating a different manufacturing process.

Claims (2)

[Claims] 1. An antibacterial agent containing silver or copper is selected from the group consisting of one or more binders selected from the group consisting of phenol resin, silicone, ucryl emulsion, vinyl acetate, rubber emulsion, urethane and liquid paraffin. Antibacterial sand formed by coating the surface of sand. 2. The method comprises the steps of heating sand at an appropriate temperature within a range of 100 to 500 ° C., and kneading the heated sand with an antibacterial agent containing silver or copper and a binder. The antibacterial sand manufacturing method.