JPS6243966B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an industrial fungicide characterized by containing 2-mercaptopyridine-N-oxide or a metal salt thereof and 1,2-benzisothiazolin-3-one as active ingredients. The industrial fungicide of the present invention comprising the above two components is
It brings about a stronger synergistic effect of antibacterial action while maintaining the antibacterial spectrum of each component. Almost everything in an aqueous organic system is prone to attack by microorganisms, which can lead to unpleasant odors and suspensions, decomposition of emulsions, coagulation of dispersions, loss of viscosity, and pH changes. This can cause various harmful effects such as changes and the formation of slime, which can greatly reduce the commercial value of the product. For example, circulating cooling type heat exchangers and waste water used in petrochemical factories or chemical factories, etc.
Slime may form in cooling pipes, clogging the pipes and reducing cooling efficiency, or microorganisms generated in white water at paper mills may form muddy slime that peels off and mixes with the paper. The paper may be cut during the process, or spots may appear on the paper.
This can cause unpleasant odors and various other problems. Metal salts of 2-mercaptopyridine-N-oxide, which is one of the active ingredients of the present invention, include alkali metal, alkaline earth metal, and zinc salts, such as sodium, potassium, calcium, magnesium, and zinc salts. These include, but are not limited to. As a result of extensive research into drug combinations that have stronger antibacterial activity than the first component alone and exhibit sustained effects, the present inventors have found that:
It has been found that the combined use of 1,2-benzisothiazolin-3-one as the second component synergistically enhances antibacterial activity and exhibits a connective effect. That is, the present inventors have found that by using these two components together, it can be expected to be effective against most objects to be sterilized, and that the sterilization effect is stronger than that when used alone. The present invention was completed by discovering an industrially significant synergistic effect in which the same effect can be achieved with a fraction of the amount of the drug used. 2-Mercaptopyridine-N-oxide or its metal salt and 1,2-benzisothiazoline-3
-one in a weight ratio of preferably 32:1 to 1:128 (generally particularly preferably 1:1 to 1:4 shows a strong synergistic effect) at a concentration of several ppm. It has become clear that the use of this method can sufficiently inhibit the growth of bacteria. In addition, since the two components exhibit a synergistic effect when used together, it is possible to significantly reduce the amount of drug used, and the cost is reduced accordingly, bringing great practical benefits. In actual use, the components of the present invention are dissolved in a hydrophilic organic solvent (dimethylformamide, ethylene glycol, methylcellosolve, etc.) and a solution (in some cases, a surfactant such as polyoxyethylene alkylamine, alkylolamine, etc.) is added. It is possible to prevent the growth of microorganisms by adding them to the system. Next, the method for testing the synergistic effect of two components used to complete the present invention will be explained. Synergistic Effect Test Method The synergistic effect between two components is measured by the binary dilution method. Both components are diluted to a predetermined concentration, and a fixed amount of each is added to the bouillon medium. Next, inoculate a certain amount of pre-cultured bacterial solution and incubate at 37℃.
After 6.5 hours of shaking culture, the concentration of both components at which no increase in absorbance at 660 nm is observed is defined as the minimum inhibitory concentration (hereinafter referred to as TDMIC) determined by the binary dilution method. Figure 1 is a graph in which the minimum inhibitory concentration (hereinafter referred to as MIC) of each component is placed equally on both axes using standard scale coordinates. In this graph, the area above the curve (i.e., the TDMIC curve) indicates the zone of growth inhibition, and the area below indicates the zone of proliferation. Furthermore, when the diagonal line and the TDMIC curve match, it indicates an additive effect, when the TDMIC curve is above the diagonal line, it indicates an antagonistic effect, and when it is below the diagonal line, it indicates a synergistic effect. Next, the present invention will be explained by examples. In the examples, compound A means the sodium salt of 2-mercaptopyridine-N-oxide, and compound B means 1.2-benzisothiazolin-3-one. Example 1 Synergistic effect against Pseudomonas aeruginosa Compound A and compound B were each administered at 100 μg/
After preparing the sample by diluting it multiple times per ml, the synergistic effect was examined according to the test method described above. The results are shown in FIG. From the figure, this TDMIC curve for Pseudomonas aeruginosa clearly indicates a significant synergistic effect. For example, the synergistic effect of the two components that completely inhibited bacterial growth was demonstrated when the concentration of compound A was 12.5 μg/ml.
It appeared when the concentration of compound B was 3.2 μg/ml. That is, this drug concentration is
It is 1/8 of the MIC of compound B alone, and the MIC of compound B alone.
The amount was approximately 1/16 of that of the drug, indicating that this drug has a strong synergistic effect. others,
Examples of combinations of concentrations of compounds A and B that produce a synergistic effect are shown in Table 1.

[Table] Figure 2 also shows the results of combinations not listed in Table 1. In the table, () represents a fraction of the individual MIC. (Hereinafter, the meaning of ( ) in the table is the same.) The MIC of compound B alone is 100 μg/ml, and the MIC of compound B alone is 50 μg/ml. Example 2 Synergistic effect on Bacillus subtilis The results of the same test as in Example 1 are shown in Table 2 and Figure 3.

[Table] Figure 3 also shows the results of combinations not listed in Table 2. Note that the MIC of Compound A alone is 3.2 μg/ml, and the MIC of Compound B alone is 3.2 μg/ml. Example 3 Synergistic effect against Staphylococcus aureus The results of the same test as in Example 1 are shown in Table 3 and FIG. 4.

[Table] Figure 4 also shows the results of combinations not listed in Table 3. Note that the MIC of Compound A alone is 3.2 μg/ml, and the MIC of Compound B alone is 50 μg/ml. Example 4 The phenomenon of contamination of underground water by slime generated at tunnel construction sites, which in turn impairs the flow of drainage ditches and even causes blockages, is occurring in various places, and at the same time, a sub-odor is emitted. The effectiveness of the mixture of the present invention was tested using slime from a drain in a certain tunnel that contained the causative bacteria. First, the present slime-forming bacteria are pre-cultured in Buimin medium. Inoculate a certain amount of the activated liquid into sterile water. Thereafter, a certain amount of diluted solutions of various mixtures of the present invention are added, and shaking culture is performed at 37°C. After shaking for a certain period of time, the number of viable bacteria was measured by the plate dilution method. The results are shown in Table 4.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a graph showing the minimum inhibitory concentration curve by the binary dilution method, and FIGS. 2, 3, and 4 are graphs showing Pseudomonas aeruginosa (FIG. 2),
FIG. 4 is a graph showing minimum inhibitory concentration curves of the industrial fungicide of the present invention against Bacillus subtilis (FIG. 3) and Staphylococcus aureus (FIG. 4) by a binary dilution method.

Claims (1)

[Claims] 1. An industrial disinfectant characterized by containing 2-mercaptopyridine-N-oxide or a metal salt thereof and 1,2-benzisothiazolin-3-one as active ingredients.