JPS59141505A - Antimicrobial agent for service water system - Google Patents

Abstract

PURPOSE:The titled agent for sterilizing or controlling micoorganisms in a service water system, preventing reduction in heat exchange efficiency in a cooling water system, containing hexabromodimethylsulfone and methylenebisthiocyanate as active ingredients. CONSTITUTION:The titled agent containing hexabromodimethylsulfone shown by the formula I and methylene bisthiocyanate shown by the formula II as active ingredients. A blending ratio of the compound shown by the formula I to the compound shown by the formula II is generally (1:19)-(19:1), especially preferably 1:1. A service water system to be used as a target is a system which causes possibly microorganism obstacle such as slime obstacle, etc., and a cooling water system or a paper-making system may be cited as the system. Target microorganisms for antimicrobial action include Pseudomonas, other bacteria, molds causing usually slime. The concentration of the two components is preferably 0.1-50mg/l calculated as pure total amount.

Description

Detailed Description of the Invention This invention aims to sterilize or suppress microorganisms in industrial water systems, in which a large amount of water is used as water for industrial purposes. As a result, the water supply system has become an environment suitable for the inhabitation and proliferation of microorganisms.

For this reason, in these water systems, slime is generated due to the proliferation of microorganisms, and for example, in cooling water systems, slime failures such as a decrease in heat transfer efficiency of heat exchangers and blockage of flow channels occur. In addition, since waste paper is reused in the paper industry,
Furthermore, slime is more likely to be generated, and slime problems such as paper breakage and spots called eyeballs in papermaking systems are occurring.

Various antibacterial agents are used to remove such slime problems in water systems, but these antibacterial agents account for a high proportion of treatment costs and are more or less toxic, so there are only a few. It is desired that the amount of antibacterial activity is high. Hexabromodimethylsulfone and methylene bisthiocyanate are known as antibacterial agents when used alone, but from the above point of view,
It could not be said that it necessarily showed excellent effects.

This invention aims to improve the antibacterial activity of conventional antibacterial agents. By using hexabromodimethyl sulfone and methylene bisthiocyanate together as active ingredients, it is possible to create a water-based antibacterial agent that exhibits excellent antibacterial activity due to a synergistic effect. is intended to provide.

Hexafromodimethyl sulfone is also called bis-(tripromonothyl) sulfone, and is represented by the following formula (I).

NC8-C-SCN --CID Hexafuromodimethylsulfone and methylene bisthiocyanate coexist as active ingredients in water systems when used as antibacterial agents, so it is sufficient to add both components to water in a mixed state. They may be added to the water simultaneously or separately. The method of addition is not particularly limited as long as it can be uniformly dispersed, but it is generally desirable to dissolve it in a solvent that is highly miscible with water, such as dimethylformamide. At this time, a dispersant can be used if necessary.

The blending ratio of hexabromodimethylsulfone and methylene bisthiocyanate is not particularly limited as long as it exhibits a synergistic effect, but it is generally preferably 1.19 to 19°1, more preferably 73 to 1. .1 is most preferred.

The antibacterial agent of the present invention may use only these two active ingredients, or may further contain other additives such as accelerators such as surfactants, or stripping agents such as hydrogen peroxide. .

The target water system is a system in which microbial damage such as slime damage may occur, such as a cooling water system or a papermaking system, but there are no particular limitations. In addition, there are no restrictions on the microorganisms that can be targeted by antibacterial treatment, and the targets are generally Pseudomonas and other bacteria that cause slime, as well as filamentous fungi. Included.

These microorganisms are completely sterilized or inhibited by the addition of the antibacterial agent of the present invention. In order to control slime damage, complete sterilization may be used, but it is also sufficient to simply suppress proliferation, and the term "antibacterial" in the present invention refers to such action.

Therefore, the added concentration of the antibacterial agent of the present invention is also a bactericidal concentration when the purpose is sterilization, and an inhibitory concentration when the purpose is inhibition. The specific addition concentration differs depending on the target water system and can be confirmed experimentally for each water system, but in general, the total amount of pure components of the two components is 0.1
~5CJmq71. The antibacterial agent may be added continuously to maintain such a bactericidal or inhibitory concentration, but once the bactericidal or inhibitory concentration is reached, it may take a considerable period of time for the propagation tendency of microorganisms to recover. Therefore, it is more efficient to add intermittently.

The antibacterial agent of the present invention has two components that exhibit a synergistic effect,
Much better antibacterial activity can be obtained than when each is used alone, and microorganisms in the water system can be sterilized or inhibited. Therefore, it is possible to prevent slime failures such as a decrease in heat exchange efficiency of a heat exchanger in a cooling water system, blockage of a flow path, or occurrence of paper breaks and spots in a papermaking system.

Next, embodiments of this invention will be described. In the examples, hexabromodimethylsulfone is referred to as Compound A, and methylene bisthiocyanate is referred to as Compound B.

Example 1 Pseudomonas, a typical bacterium that breeds in industrial water
After culturing A. aeruginosa in bouillon medium for 24 hours with shaking, 5 × 1
Compounds A and B were added at different mixing ratios, and the presence or absence of bacterial growth was determined after 24 hours, and the minimum inhibitory concentration (purity equivalent...・The same applies hereafter) was calculated.

The results are shown in Table-1.

As is clear from Table 1, a synergistic effect was observed over a wide range of blending ratios of 1:19 to 19:1 in combination with Compounds A and B, and the effect was even greater at ratios of 7:6 to 3. :1 is the thickest.

Table 1 Example 2 After adding 1 part of bouillon culture medium to 9 parts of paper-making white water at a paper mill, a mixed solution of compounds A and B (865 parts of compound A and B dissolved in 90 parts of N-bimethylformamide) was prepared. ), and 24 hours later, the presence or absence of bacterial growth was determined.
The minimum inhibitory concentration after time was determined. For comparison, a similar test was carried out using a case in which each compound (A%, B) was added alone. The results are shown in Table-2.

As is clear from Table 2, a synergistic effect is observed in the mixture of compounds A and B.

Table 2 Example 6 In the papermaking system of a paper mill where slime damage has occurred, the compound A1 B mixture used in Example 2 was added to white water at a rate of 15 to 7 (purity equivalent) three times a day. ), the number of eyeballs caused by slime decreased from 45 times per day to 910 times per day.

Example 4 The mixed solution of compounds A and B used in Example 2 was added to the circulating cooling water system of a chemical factory once every two days so that the amount of water retained was 25η/l (purity equivalent). The amount of slime attached to the slime board (10 parts wL x 10cn'L) immersed in the water tank at the bottom of the cooling tower for 3 days was as follows:
The weight has been reduced from the previous 28.9 to 25g.

The above results show that the antibacterial agent of the present invention exhibits excellent antibacterial activity due to the synergistic effect.

Agent: Patent attorney Sei Yanagi Hara

Claims (4)

[Claims] (1) A water-based antibacterial agent containing hexabromodimethylsulfone and methylene bisthiocyanate as active ingredients. (2) The blending ratio of hexabromodimethyl sulfone and methylene bisthiocyanate is 1 = 19 to 19:1
A water-based antibacterial agent according to claim 1. (3) The water-based antibacterial agent according to claim 1, wherein the blending ratio of hexabromodimethylsulfone and methylene bisthiocyanate is 7.6 to 6:7. (4) The antibacterial agent for a water system according to any one of claims 1 to 6, wherein the water system is a cooling water system or a papermaking system.