FI76237C - BIOCIDISK SAMMANSAETTNING. - Google Patents

Description

1 76237

Biocidal composition

Industrial circulating water systems normally contain a large number of different types of microorganisms which, without treatment with a suitable pesticide, can cause significant adverse effects on the operation of the equipment or cause adverse side effects. Pesticides used for these purposes are primarily required to have a very broad spectrum of performance, with the least possible dependence on environmental factors such as pH, temperature and other substances present in the system at the same time. It follows from these requirements for the effectiveness of pesticides for the treatment of circulating water systems that they have generally been able to be used for other purposes as well, such as as a preservative in various pulps (wood, kaolin, talc, CaCO, etc.).

Numerous different types of bactericidal and fungicidal agents have been used to control the microorganisms in the circulating water and the mucilages they form, such as organomercury compounds, chlorinated phenol derivatives, thiocarbamates, thiocyanates, quaternary ammonium compounds, organic thiium compounds. It is known from U.S. Pat. No. 3,929,561 to use in industrial circulating water systems a synergistic biocidal mixture against microorganisms with 75% 5-chloro-2-methyl-4-isothiazolin-3-one and 25% 2-methyl-4 -isothiazolin-3-one mixed with bis (t-dichloromethyl) sulfone and calcium chloride. It is also known from U.S. Pat. No. 4,295,932 to use a mixture of the active ingredients, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, for controlling microorganisms in circulating water systems. is mixed with chlorine or chloride oxy di n. It is further known to use 8-hydroxyquinoline or its copper chelate against microorganisms.

76237 2

When selecting a suitable pesticide for the treatment of industrial waters, the toxicity, stability, ease of use, and efficacy against as many microorganisms as possible must be taken into account. In particular, the efficacy of the substance against as many bacterial, mold, yeast and algal species as possible in practice is important, as if the efficacy of the substance used is clearly weak for some species, these resistant species may become enriched in the system under treatment.

The synergistic biocidal composition of the present invention eliminates the above-mentioned disadvantages and enables effective control of microorganisms. Namely, it has now surprisingly been found that 8-hydroxyquinoline together with isothiazolone compounds produces a synergistic effect against bacteria and fungi. As the isothiazolone compound, 5-chloro-2-methyl-4-isothiazolin-3-one and / or 2-methyl-4-isothiazolin-3-one are used, which together with 8-hydroxyquinoline provide an inhibitory effect on both bacterial and fungal growth. If the mixture contains more than one active substance, the number of resistant organisms is considerably lower than for the substances alone, because their spectra of action are not identical. In addition, due to the better activity of the mixture, the total amount of biocide required for efficient handling can be reduced.

In order for the combination of active ingredients according to our invention to be effectively used for the treatment of industrial circulating water, they must be formulated in either a water-soluble or easily dispersible form. Various solvents, emulsifiers and stabilizers can be used for this purpose. The preferred solvent is a polar solvent, and a nonionic emulsifier is preferably used as the emulsifier. Any suitable stabilizer is used as the stabilizer. Optionally, a carrier may also be added to the mixture, in which case the mixture may be used in solid form.

3,76237

The effectiveness of the biocidal composition of our invention is described below by way of examples.

Example 1 This example illustrates the ability of a biocidal composition of the invention to affect the oxygen consumption of a bacterium (Enterobacter aerogenes ATCC 7256). The inhibitory potency of the drug mixture was measured on a Gilson GR 14 respirometer at concentrated pressure and temperature. Nutrient Broth solution was used as the nutrient solution and the pH was adjusted to 7.0. Bacterial respiration inhibited by biocides was measured as a percentage after 100 minutes.

Measurable solutions were prepared from the biocides. 10% of 8-hydroxyquinoline was dissolved in a polar solvent (solution A) and a 1.0% mixture of 75% of 5-chloro-2-methyl-4-isothiazolin-3-one and 25% of 2- methyl-4-isothiazolin-3-one in the same polar solvent (solution B). Mixtures were prepared in which the ratio of solution A to solution B was 1: 3, 1: 1 and 3: 1.

The results are shown in Table 1 and graphically in Figure 1.

table 1

Solution A: Solution B Cons. A: B Inhibited by the active substance mixture _____ (mg / l) ____ bacterial respiration (¾) _ 100: 0 150 100: 0 60.4 3: 1 150 30: 1 66.3 1: 1 150 10: 1 78.9 1: 3,150 3.3: 1,84.2 0: 100 150 0: 100 64.8

Example 2

The potency assay of the biocidal composition of the invention was performed using the Nutrient Agar method modified by the Con-Kay-Carlson method (Pin 46 (1963) (5), 23-24).

4,76237

To demonstrate a synergistic effect, the minimum inhibitory concentrations (MICs) of the active ingredients in the agar plating media, i.e. the concentration at which the agar surface is completely clean, were determined. Solutions A and B were prepared as in Example 1 and their MIC values were compared to the MIC values of the A / B mixtures at approx. Kull et al. (FC Kull, PC Eismann, HD Sylvestrowicz, RL Mayer, Appl. Microbiol. (1961) 9, 538-541) a synergistic effect is obtained which can be calculated by the following formula: QÄ + = x U * 5 * abx = 1 denotes additivity x> 1 denotes antagonism x <1 denotes synergism Q = concentration of substance A, which means MIC a Q = concentration of substance B, which means MIC b

Q = amount of substance A at the concentration of A / B that inhibits A

microbial growth

Q = the amount of substance B in the concentration of A / B that inhibits B

microbial growth.

A mixture of fungi (Penicillium expansum and

Aspergillus niger) inoculated on Bacto potato dextrose agar and incubated for 2 weeks at + 27 ° C. The biocide solutions of Example 1 were mixed at the desired concentrations with nutrient agar (15 g Bacto-Malt extract + 15 g Bacto agar). A 2-week-old mold was inoculated on agar. Incubated for 2 weeks at 1 ° C 1 7 C. The inhibitory rate (MIC) is the concentration at which the agar surface is completely clean. The results obtained are shown in Table 2 and graphically in Figure 2.

5,762 37

Table?

Weight ratio MIC QQ, QQ / QQ / 0 * iiS _____ SäZlJH9 / 1 »a / 1 · ϋ / ι -i} / i A b B b____ 100: 0 80 80 15 80 - 1 - 1 30: 1 62 80 15 60 2, 0 0.75 0.13 0.88 10: 1 44 80 15 40 4.0 0.50 0.27 0.77 3'3: 1 26 80 15 20 6.0 0.25 0.40 0.65 0: 100 15 80 15 - 15 _ 1 1

Example 3

The potency assay for bacterial strains was performed by the nutrient agar method (modified Conkay-Carlson method).

Bacterial strains (Enterobacter aerogenes, Bacillus subtitilis, Pseudomonas aeruginosa) were inoculated on Bacto tryptone Glucos extract agar and incubated for 3 days at + 37 ° C.

The biocide mixture was mixed at the desired concentrations with molten agar and the cultured bacterial mixture was inoculated on a solidified surface. After three days, the growth was checked. The inhibition concentration (MIC) is the concentration at which the agar surface is completely clean.

The following compositions were prepared from the biocides:

Solution A: 8-hydroxyquinoline Cu chelate 15.0% sulfuric acid (93%) 20% water, stabilizers 65%

Solution B: 5-Chloro-2-methyl-4-isothiazolin-3-one 1.57¾ 2-methyl-4-isothiazolin-3-one 0.53% water, stabilizers 97.9% 762 37 6

For the experiment, mixtures A and B were prepared in which the ratio of solution A to solution B was 1: 3 and 1: 1. The results are shown in Table 3.

Table 3

Weight ratio MIC qqq / q Q / Q x A: B_mg / 1 mg / 1 mg / 1 mg / 1 mg / 1 A & B b__ 100: 0> 90> 90 4.2 <90-1 - 1 7.1: 1 17 .1> 90 4.2 15 2.1 <0.17 0.50 <0.67 2.4: 1 10.6> 90 4.2 7.5 3.1 <0.08 0.74 <0 , 82 0: 100 4.2> 90 4.2 - 4.2 - 1 1

Example 4

A biocide mixture (product A) containing 7% of 8-hydroxy quinoline and 0.7% of a mixture of 75% of 5-chloro-2-methyl-4-isothiazoline-3-active compound was added to the circulating water system of a paper machine producing wood-free printing papers. and 25% 2-methyl-4-isothiazolin-3-one. Biocide mixture A was applied at the following points: 1) stern feed pump (85 ml / min, 3 x 75 min / d) 2) wreck (75 ml / min, 3 x 75 min / d) 3) LTO towers (50 ml / min) , 2 x 20 min / d)

In another experiment, a product containing 2.1% of a mixture of 75% of 5-chloro-2-methyl-4-isothiazolin-3-one and 25% of 2-methyl-4-isothiazoline was added to the same points as the active ingredient. 3-one. The dosage amounts were also the same as for product A.

Bacterial densities in the wire well and wreck were determined during the test run as well as before the test run using the Millipore "Dip-Stick" method. The results obtained are shown in Table 4.

7,762 37

Table 4

Test Biocide used Bacterial density (pcs / ml) ________vi i rakai vo_wort 4 5 4 1 product B 10-10 10 5 6 4 2 "B 10-10 10„ 3 4 4 3 product A 10-10 10 4 4 4 "A 10 10 4 4 5 "A 10 10 4 5 4 6" A 10-10 10 4 4 7 "A 10 10

As can be seen from the table, the bacterial densities had remained at a lower level during the test run than before the test run. There were also no suction difficulties during the test run.