MICROBICIDAL PREPARATIONS BASED ON 1,2-BENZISOTHIAZOLIN-3-ONEMICROBICIDAL PREPARATIONS BASED ON 1,2-BENZISOTHIAZOLIN-3-ONE

Abstract

The invention relates to microbicidal preparations which comprise a) at least one of 1,2-benzisothiazolin-3-one and its derivatives, b) at least one of 2-mercaptopyridine N-oxide, its salts and derivatives and c) at least one alkalinizing agent, or which are prepared by mixing components a) to c), where the preparations have a pH of at least 11. The preparations are characterized by the fact that they are clear and storage-stable, and they are suitable for use as preservatives.

Description

EXAMPLE 1

Decomposition of 2-n-octylisothiazolone at a pH of 35 about 13

1.1% by weight of Kathon 893F (2-n-octylisothiazolone, 45% strength in glycol), 48.89% by weight of methanol and 50% by weight of sodium hydroxide solution (c=0.5 mol/l) were used to prepare a mixture with a pH of about 13 whose active ingredient content (in % by wt.) was monitored using HPLC over a period of 35 days. Storage took place at 20° C. The results are shown below.

This shows that 2-alkylisothiazolones, such as 2-n-octylisothiazolone, are not stable under alkaline conditions.

EXAMPLE 2

The following preparations were prepared by mixing the stated components. The quantitative data in the table refer to the amounts of active constituent. 2-Mercapto-pyridine N-oxide was used as the sodium salt sodium pyrithione (40% strength aqueous solution), 1,2-benzisothiazolinone was used as 85% strength hydrous solid. Potassium hydroxide and sodium hydroxide were in each case used as 45% strength aqueous solution.

	I	II (comparison)	III	IV (comparison)
1,2-Benzisothiazolin-3-one	9.0	9.0	7.6	9.0
Sodium pyrithione	5.6	5.6	7.6	5.6
Potassium hydroxide	4.5	3.6	—	—
Sodium hydroxide	—	0.9	2.0	—
Phenoxyethanol	—	—	—	10.0
Water	ad 100	ad 100	ad 100	ad 100
Solubility and appearance	Dissolved after	Dissolved after 10 min, clear	After filtration,	Not dissolved,
after preparing the	10 min, clear,	brownish-yellow solution	clear, orange-	cloudy, yellowish
preparation	brownish-yellow		yellow solution	solution with a lot
	solution			of sediment
Gardner colour number	4.4	4	3.8
after preparation
pH (pH paper) after	13-14	13-14	12.2	8-9
preparation
Appearance after storage	frozen	frozen	Very good storage	Without change
for 2 days at −5° C.			stability over at
Appearance after storage	Without change	frozen	least three
for 2 days at +4° C.			months at +40° C.
Appearance after storage	Without change	Without change
for 2 days at 25° C.

Claims

1. Preservative preparation which comprises a) at least one of 1,2-benzisothiazolin-3-one and its derivatives,b) at least one of 2-mercaptopyridine N-oxide, its salts and derivatives andc) at least one alkalinizing agent,or which is prepared by mixing components a) to c),where the preparation(i) has a pH of at least 11 and(ii) is free from ethylenediamine, if the weight ratio of component a) to component b) is greater than 2.1.

2. Preparation according to claim 1 which comprises more than 30% by weight of water, preferably more than 50% by weight of water, more preferably 60 to 90% by weight of water, such as 80 to 85% by weight of water.

3. Preparation according to claim 1 which is free from N-alkylisothiazolin-3-one.

4. Preparation according to claim 1, characterized in that its pH is at least 12, preferably at least 12.2, more preferably 12.6 to 13.6, in particular 12.8 to 13.3.

5. Preparation according to claim 1, characterized in that component a) is 1,2-benzisothiazolin-3-one.

6. Preparation according to claim 1, characterized in that the amount of component a) is 1 to 20% by weight, preferably 3 to 17% by weight, more preferably 5 to 15% by weight, such as 6 to 12% by weight, for example 7.5 to 9.5% by weight.

7. Preparation according to claim 1, characterized in that the salt of 2-mercaptopyridine N-oxide is an alkali metal, alkaline earth metal or zinc salt, where the sodium salt of 2-mercaptopyridine N-oxide is particularly preferred as component b).

8. Preparation according to claim 1, characterized in that the amount of component b) is 1 to 20% by weight, preferably 2 to 15% by weight, more preferably 3 to 12% by weight, such as 4 to 10% by weight, for example 5 to 8% by weight.

9. Preparation according to claim 1, characterized in that the alkalinizing agent is an alkali metal hydroxide, where potassium hydroxide, sodium hydroxide or a mixture of sodium hydroxide and potassium hydroxide is particularly preferred as component c).

10. Preparation according to claim 1, characterized in that the amount of component c) is 0.3 to 10% by weight, preferably 0.5 to 8% by weight, more preferably 1 to 7% by weight, such as 1.5 to 6% by weight, for example 2.0 to 4.5% by weight.

11. Preparation according to claim 1, characterized in that it also comprises d) one or more aromatic alcohols chosen from (i) aryloxyalkanols (glycol monoaryl ethers), (ii) arylalkanols and (iii) oligoalkanol aryl ethers, where phenoxyethanol, phenoxypropanols, benzyl alcohol and mixtures thereof are particularly preferred as component d).

12. Preparation according to claim 11, characterized in that the amount of component d) is 1 to 25% by weight, preferably 3 to 20% by weight, more preferably 5 to 15% by weight, such as 7 to 13% by weight, for example about 10% by weight.

13. Process for preparing the water-containing preparation according to claim 2, in which component b) is initially introduced into water, then component a) is added and then component c) and optionally finally component d).

14. Process for preparing the water-containing preparation according to claim 2, in which component a) is initially introduced into water, then component c) is added and then component b), and then the mixture can optionally be diluted to the desired concentration with water.

15. (canceled)

16. Method of preventing or reducing the microbicidal attack of a composition in which the composition is treated with an effective amount of the preparation according to claim 1.

17. Microbicidally finished product, characterized in that it comprises the preparation according to claim 1.

18. Preparation according to claim 2 which is free from N-alkylisothiazolin-3-one.