JP3154371B2 - Manufacturing method of antibacterial material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an antibacterial material.

[0002]

2. Description of the Related Art In recent years, when synthetic resin products are frequently used, or when used in a field that requires attention to hygiene such as kitchen utensils, contamination of the surface of the synthetic resin by bacteria is a problem. It is becoming. In addition, fungi and fungi grow on the surface of caulking materials used as building materials,
There are problems such as poor hygiene or appearance. As a countermeasure, a method of mixing an antibacterial material into a synthetic resin and dissolving the antibacterial material on the surface of the synthetic resin to sterilize the resin surface has been used. Further, an organic antibacterial and antifungal material such as thiabendazole is used in order to positively elute the antibacterial and antifungal material in the synthetic resin and obtain a bactericidal and fungicidal effect on and around the resin surface. In addition, since the antibacterial material does not guarantee permanent and complete sterilization of the surface, regular surface sterilization can maintain the cleanliness more. As the surface sterilization in this case, a chlorine bleach such as sodium hypochlorite has been generally used. Further, refrigerators and air purifiers equipped with a deodorizing and fungicidal unit equipped with phytoncide extracted from plants have been proposed.

[0003]

Since the above-mentioned organic antibacterial and antifungal material has volatility, if it is contained in a synthetic resin, the surrounding environment of the synthetic resin is contaminated and the surface of the synthetic resin comes into contact. The wastewater contains antibacterial and antifungal materials, which cause wastewater pollution.
Furthermore, there is a problem that it affects activated sludge during sewage treatment. Also, in the case of a silver-based antibacterial agent using silver ions (Ag ⁺ ), if a bleaching agent commonly used in the kitchen is used, silver ions react with chlorine ions in the chlorine-based bleach to form insoluble silver chloride, Furthermore, since silver chloride has a high photoreaction activity, it immediately changes to metallic silver or silver oxide, causing not only blackening, but also a reduction in antibacterial performance.

Further, when kneaded in a resin, the refractive index of the carrier used for stabilizing the silver salt is different from that of the kneaded resin. There were also problems such as impairing the performance.
Furthermore, plant extracts are often aromatic substances and have volatility, so when these substances are mixed into resin,
There is a problem that the resin cannot be mixed because it is evaporated by heating during molding of the resin. An object of the present invention is to provide an antibacterial material showing a stable antibacterial effect on a resin surface. It is another object of the present invention to provide an antibacterial material which is less likely to cause environmental pollution even if it is eluted from the resin.

[0005]

The method for producing an antibacterial material of the present invention comprises dissolving at least one soluble silver salt selected from the group consisting of silver acetate, silver sulfate and silver nitrate in pure water,
The method includes a step of sequentially adding potassium sulfite and potassium thiosulfate or a sodium sulfite and sodium thiosulfate to the solution to dissolve the solution, and a step of evaporating the obtained solution to dryness. The method further includes a step of forming a coating layer on the outer surface of the solid particles obtained by evaporating to dryness. Here, the molar ratio of silver ion and sulfite ion in the solution is 1: 1 to 1
6. The molar ratio of silver ion to thiosulfate ion is preferably 1: 1 to 8. The coating layer preferably contains at least one of silicon dioxide, low melting point wax, metal soap, and antioxidant.

[0006]

The antimicrobial material according to the present invention does not require a carrier because the antimicrobial material itself has high stability, and when kneaded in the resin, has the effect of maintaining the transparency of the resin and the smoothness of the resin surface as they are. Further, it is possible to pulverize the antibacterial material without being limited by the particle size of the carrier as in the conventional antibacterial agent. By making the S ₂ O ₃ ²⁻ / Ag ⁺ ratio 1 to 8 and the SO ₃ ²⁻ / Ag ⁺ ratio 1 to 6 in the raw material, the stability of the produced antibacterial material, especially the heat discoloration resistance, is improved. Can be done. Further, most of silver forms a complex and is stabilized, so that a stable antibacterial action can be obtained. Further, elution from the resin hardly causes environmental pollution. Further, by forming a coating layer on at least a part of the surface of the antibacterial material, the antibacterial substance has a sustained release property and the thermal stability is improved. Further, even when used in an atmosphere having a high chlorine concentration, discoloration does not occur and antibacterial performance is not reduced. In addition, by using silver sulfate or silver nitrate instead of silver acetate in the raw material, the residual acetic acid radical is eliminated in the produced antibacterial material, and the acetic acid odor of the antibacterial material and the acetic acid at the time of kneading and molding the resin of the antibacterial material are kneaded. Odor can be removed.

[0007]

Embodiments of the present invention will be described below. Example 1 Silver acetate CH ₃ COOAg was used as a silver salt. Since silver acetate has a low solubility, it is 7.7 close to the solubility.
g / l at a temperature below 60 ° C. In this dissolving step, if the temperature is higher than 60 ° C., silver acetate is decomposed. Next, in the silver compound reaction step, first, potassium sulfite K ₂ SO ₃ is converted to CH ₃
COOAg was added at a rate of 2.7 g / g, and after sufficient dissolution, potassium thiosulfate K ₂ S ₂ O ₃ was added to CH ₃ CO 2.
6.6 g per 1 g of OAg is added and dissolved. The temperature in this melting step is preferably in the range of 40 ° C. to room temperature. Next, the evaporating and drying of the silver compound solution was carried out at a normal pressure and at a temperature of 40 ° C. so that the silver compound was not decomposed. The pressure in this step is normal pressure to 10 ^-4 Pa,
The temperature is preferably from 40C to 120C. Thus, a silver-based antibacterial material is obtained. Then, it is preferable to pack in a moisture-resistant, reduced-pressure pack so as to withstand long-term storage and preservation. The antibacterial material produced by the above method was uniformly dispersed at a ratio of 1.5 parts by weight to 100 parts by weight of the resin at the time of molding the polypropylene resin to obtain a resin molded body.

Example 2 In the same dissolving step as in Example 1, the solution is prepared, dried and pulverized to an average particle size of about 10 μm to obtain an antibacterial material comprising a silver compound. For 100 parts by weight of this antibacterial material, 50 parts by weight of a phenolic primary antioxidant (Sumitomo Chemical: trade name Sumilize)
r GS) and heated to 120 ° C. slightly higher than the melting point of the antioxidant to coat the surface.
1.5 parts by weight of the antibacterial material thus produced was mixed with 100 parts by weight of the ABS resin to obtain a resin molded body.

Comparative Example 1 A solution using the same materials as in Example 1 except that silver acetate was not contained was evaporated to dryness under the same conditions. The obtained solid particles were kneaded with a polypropylene resin to obtain a resin molded body.

The resin molded articles of Examples 1 and 2 and Comparative Example 1 were subjected to the following antifungal test and antibacterial test. Anti-mold test: Mold resistance test according to Japanese Industrial Standards (JIS Z)
2911) according to the halo test method based on a fungicide test for textile products. The molds used were Cladosporium cladosporioides, Chaetomium globosum, Penicillium citrinum and Asperigillus niger.
Evaluation was performed 14 days later. Antibacterial test: Escherichia cole
i), Staphylococcus aureus (Staphylococcu
s aureus) and Bacillus subtilli
s) and according to the dropping method. The evaluation was performed after 24 hours.

The results of the test are shown in Table 1. Table 1 shows that the antibacterial materials of Examples 1 and 2 have practical antibacterial and antifungal properties. By replacing some or all of the potassium ions in the above raw materials with sodium ions, an antibacterial material having properties slightly inferior to those using potassium ions but practically acceptable was obtained.

[0012]

[Table 1]

Example 3 In the same dissolving step as in Example 1, a silver compound solution was prepared and evaporated to dryness to obtain an antibacterial material comprising a silver compound. Next, a method of forming a shell coating layer on silver compound particles by a sol-gel method will be described. This coating layer allows for adjustment of the duration of the antibacterial and antifungal pharmacological effects of the silver compound. That is, it is possible to control the persistence of the drug treatment effect by the area and the thickness of the coating layer. 1 g of the silver compound was added to 1 ml of ethyl alcohol and 1 ml of tetraethoxysilane.
In addition, after mixing well, about 0.2 ml of pure water was added dropwise to hydrolyze tetraethoxysilane to form an outer shell coating layer of silicon dioxide on the surface of the silver compound. The reaction proceeds further by absorbing moisture in the air. Heating at a temperature less than about 60 ° C. accelerates the reaction. It is suitable to use an alkoxysilane having 1 to 4 carbon atoms as an alkoxysilane and an alcohol having 1 to 4 carbons as an alcohol for forming the coating layer.

K ₂ S ₂ O ₃ or K ₂ added in the silver reaction step
A silver compound was obtained in the same manner as in Example 1 except that the ratio of S ₂ O ₃ ^2- / Ag ⁺ or SO ₃ ^2- / Ag ⁺ was changed by changing the amount of SO ₃ added. An outer shell coating layer of silicon dioxide was formed on these by the method described above. 1.5 parts by weight of the antibacterial composition thus obtained was mixed with 100 parts by weight of a polypropylene resin and molded at 220 ° C. or 240 ° C. Tables 2 and 3 show the relationship between the presence / absence of discoloration and the presence / absence of antibacterial effect and the ratio of S ₂ O ₃ ^2- / Ag ⁺ or SO ₃ ^2- / Ag ⁺ at the time of molding of these molded products. From these results, when the S ₂ O ₃ ²⁻ / Ag ⁺ ratio in the raw material is less than 1, the stability of the product is poor, and when it exceeds 8, the K ₂ S ₂ O
_{Because of the} large amount of precipitation of ₃ and poor workability, it has good heat discoloration resistance in the range of 1 to 8. Similarly, SO ₃ in the raw material
^{If the 2-} / Ag ⁺ ratio is less than 1, the stability of the product is poor,
If it exceeds 6, the K ₂ SO ₃ of the raw material is largely precipitated and the workability is poor.

[0015]

[Table 2]

[0016]

[Table 3]

Although silver acetate was used as a silver raw material in the above embodiment, similar antibacterial performance was obtained by using silver sulfate or silver nitrate instead. By using silver sulfate instead of silver acetate in the raw material, the residual acetic acid radical in the produced antibacterial material can be eliminated, and acetic acid odor of the antibacterial material and acetic acid odor at the time of kneading and molding the resin of the antibacterial material can be removed. Further, in the examples, an example in which an antioxidant and silicon dioxide were used as the surface coating material was shown. However, depending on the type of the resin to be kneaded, the application for coating, etc., the same applies even when a low-melting wax or metal soap is used. The effect can be obtained.

[0018]

As described above, the antibacterial material according to the present invention does not require a carrier because the antibacterial material itself has a high stability. In other words, there is an effect of maintaining the transparency of the resin and the smoothness of the resin surface as they are. Further, the antibacterial material can be finely pulverized without being limited by the particle size of the carrier as in the case of the conventional antibacterial agent, and the coating material can be formed. further,
The S ₂ O ₃ ²⁻ / Ag ⁺ ratio in the raw material was changed from 1 to 8, and SO ₃ ²⁻
By setting the / Ag ⁺ ratio to 1 to 6, the stability of the resulting antibacterial material, particularly the heat discoloration resistance, can be improved. In addition, most of silver forms a complex and is stabilized, so that a stable antibacterial effect can be obtained. Further, elution from the resin hardly causes environmental pollution. Further, by forming the outer shell coating layer on at least a part of the surface of the antibacterial material, the antibacterial material has a sustained release property and the thermal stability is improved. Further, even when used in an atmosphere having a high chlorine concentration, discoloration and deterioration of antibacterial performance do not occur.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenji Hoshino 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-6-1706 (JP, A) JP-A-6-1707 (JP, A) JP-A-6-125970 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) A01N 59/16

Claims (5)

(57) [Claims] 1. A silver acetate, was dissolved in pure water at least one soluble silver salt selected from the group consisting of silver sulfate and silver nitrate, potassium sulfite and thiosulfate potassium and forward <br/> next added to the solution And dissolving the resultant solution, and evaporating and drying the obtained solution to obtain solid particles . 2. The method according to claim 1, wherein the solution is subjected to a normal pressure of 10 to 10 ^-4 Pa
And evaporating to dryness at a temperature of 40 to 120 ° C.
The method for producing the antibacterial material described above. 3. The method according to claim 1, further comprising the step of forming a coating layer on the outer surface of the solid particles obtained by evaporating and drying the solid particles.
Or the method for producing an antibacterial material according to 2 . Wherein the molar ratio of silver ion and sulfite ion in the solution is 1: 1 to 6, the molar ratio of silver ion and thiosulfate ion is 1: any of claims 1-3 is 1-8 A method for producing the antibacterial material according to the above. 5. The method for producing an antibacterial material according to claim 3 , wherein the coating layer contains at least one selected from the group consisting of silicon dioxide, low melting point wax, metal soap and antioxidant.