The invention relates to a biocide composition as an addition to substances that can be infected by harmful microorganisms. In particular the invention concerns a biocide composition having at least two active biocidal substances that interact synergistically, in which one of the active substances is 2-methylisothiazolin-3-one.
Biocidal agents are used in many fields, for example, to control harmful bacteria, fungi, or algae. The use of 4-isothiazolin-3-ones (which are also designated as 3-isothiazolones) in such compositions has been known for a long time, since these include very effective biocidal compounds.
One of these compounds is 5-chloro-2-methylisothiazolin-3-one. Whereas it does indeed exhibit good biocidal activity, there are various disadvantages when it is handled in practice. For example, the compound frequently triggers allergies in persons that use it. Also, there are legal restrictions in many countries on the AOX value of industrial waste waters, i.e., a certain concentration of organic chlorine, bromine, and iodine compounds that can adsorb to activated carbon must not be exceeded in the water. This prevents the use of 5-chloro-2-methylisothiazolin-3-one to the desired extent. Furthermore, the stability of this compound is inadequate in certain circumstances, e.g., at high pH values or in the presence of nucleophiles or reducing agents.
Another known isothiazolin-3-one with biocidal activity is 2-methylisothiazolin-3-one. While it is true that the compound avoids various disadvantages of 5-chloro-2-methylisothiazolin-3-one, for example, the high risk of allergy, its biocidal activity is considerably lower. Thus, a simple substitution of 2-methylisothiazolin-3-one for 5-chloro-2-methylisothiazolin-3-one is not possible.
The use of combinations of various isothiazolin-3-ones or combinations of at least one isothiazolin-3-one and other compounds is also already known. For example, a synergistic biocidal composition that contains 2-methylisothiazolin-3-one (2-methyl-3-isothiazolone) and 2-n-octylisothiazolin-3-one (2-n-octyl-3-isothiazolone) is described in EP 0676140 A1.
Synergistic biocide compositions that are combinations of 1,2-benzisothiazolin-3-one and an iodopropargyl compound (iodopropinyl compound) are known from U.S. Pat. No. 5,328,926. For example, 3-Iodopropargyl-N-butyl carbamate is named as such a compound. In the said document, however, no biocide compositions are described that contain further active biocidal substances besides 1,2-benzisothiazolin-3-one and 3-iodopropargyl-N-butyl carbamate.
In JP 01224306 (Chemical Abstracts, Vol. 112, Nos. 11, Mar. 12, 1990, Abstract No. 93924), a biocide composition is described that consists of 2-methylisothiazolin-3-one, 1,2-benzisothiazolin-3-one, and 5-chloro-2-methylisothiazolin-3-one.
JP 06092806 (Chemical Abstracts, Vol. 121, Nos. 11, Sep. 12, 1994, Abstract No. 127844) relates to biocide compositions that contain an isothiazolinone, 1,2-benzisothiazolin-3-one, and propanol or a propanol derivative. 2-Methylisothiazolin-3-one is named, for example, as the isothiazolinone and 2-bromo-2-nitropropane-1,3-diol, for example, as the propanol derivative. However, no reference is made to a composition that specifically contains 2-methylisothiazolin-3-one, 1,2-benzisothiazolin-3-one, and 2-bromo-2-nitropropane-1,3-diol and is simultaneously free of 5-chloro-2-methylisothiazolin-3-one.
The object of the invention is to provide a biocide composition that is improved in that its components interact synergistically and therefore can be used in lower concentrations when used simultaneously, compared to the concentrations necessary in the case of the individual components. Thus, humans and the environment are exposed to less pollution and the costs of controlling harmful microorganisms are reduced.
This object is achieved by the invention by means of a biocide composition having at least two active biocidal substances, one of which is 2-methylisothiazolin-3-one. The composition is characterized in that it contains as a further active biocidal substance 1,2-benzisothiazolin-3-one, biocide compositions containing 5-chloro-2-methyl-isothiazolin-3-one, being excluded.
The biocide composition of the invention has the advantage that it can replace active substances used until now in practice, but suffering from disadvantages with respect to health and the environment, e.g., 5-chloro-2-methylisothiazolin-3-one. Moreover, the biocide composition of the invention can be produced with water as a favorable medium, if necessary. The addition of emulsifiers, organic solvents, and/or stabilizers is thus not necessary. Moreover the invention makes it possible to match the composition to specific goals by adding further active substances, for example, in the sense of an increased biocidal activity, improved long-term protection of the substances infected by microorganisms, improved compatibility with the substances to be protected, or improved toxicological or ecotoxicological behavior.
The biocide composition of the invention contains 2-methylisothiazolin-3-one and 1,2-benzisothiazolin-3-one, normally in a weight ratio of (50-1): (1-50), preferably in a weight ratio of (15-1): (1-8), in particular in a weight ratio of (4-1) (1-4). A weight ratio of 1:1 is particularly preferred.
In the biocide composition the 2-methylisothiazolin-3-one and the 1,2-benzisothiazolin-3-one are present in a total concentration of preferably 0.5 to 50% by wt, in particular 1 to 20% by wt, particularly preferred 2.5 to 10% by wt, in each case relative to the total biocide composition.
It is advisable to use the biocides of the composition of the invention in combination with a polar or nonpolar liquid medium. This medium can be supplied, for example, in the biocide composition and/or in the substance to be preserved.
Preferred polar liquid media are water, an aliphatic alcohol having 1 to 4 carbon atoms, e.g., ethanol and isopropanol, a glycol, e.g., ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, and tripropylene glycol, a glycol ether, e.g., butyl glycol and butyl diglycol, a glycol ester, e.g., butyl diglycol acetate or 2,2,4-trimethylpentanediol monoisobutyrate, a polyethylene glycol, a polypropylene glycol, N,N-dimethylformnamide, or a mixture of such substances. The polar liquid medium is in particular water, where the pH value of the corresponding biocide composition is preferably adjusted to be neutral or weakly alkaline, for example, to a pH value of 7 to 9. Thus, the 2-methylisothiazolin-3-one is then present in dissolved form and the 1,2-benzisothiazolin-3-one is present in finely dispersed form, or both active substances are dissolved.
For example, aromatics, preferably xylene and toluene, serve as nonpolar liquid media.
The biocide composition of the invention can also be combined simultaneously with a polar and a nonpolar liquid medium.
In addition to 2-methylisothiazolin-3-one and 1,2-benzisothiazolin-3-one, the biocide composition of the invention can contain one or more other active biocidal substances, selected in accordance with the field of application. Specific examples of such additional active biocidal substances are shown below:
benzyl alcohol
2,4-dichlorobenzyl alcohol
2-phenoxyethanol
2-phenoxyethanol hemiformal
phenylethyl alcohol
5-bromo-5-nitro- 1,3-dioxane
formaldehyde and formaldehyde source materials
dimethyloldimethyl hydantoin
glyoxal
glutardialdehyde
sorbic acid
benzoic acid
salicylic acid
p-hydroxybenzoic acid ester
chloroacetamide
N-methylolchloroacetamide
phenols, such as p-chloro-m-cresol and o-phenylphenol
N-methylolurea
N,Nxe2x80x2-dimethylolurea
benzyl formal
4,4-dimethyl- 1,3-oxazolidine
1,3,5-hexahydrotriazine derivatives
quaternary ammonium compounds, such as
N-alkyl-N,N-dimethylbenzyl ammonium chloride and
di-n-decyldimethyl ammonium chloride
cetylpyridinium chloride
diguanidine
polybiguanide
chlorohexidine
1,2-dibromo-2,4-dicyanobutane
3,5-dichloro4-hydroxybenzaldehyde
ethylene glycol hemiformal
tetra(hydroxymethyl)phosphonium salts
dichlorophen
2,2-dibromo-3-nitrilopropionic acid amide
3-iodo-2-propinyl-N-butyl carbamate
methyl-N-benzimidazol-2-yl carbamate
2-n-octylisothiazolin-3-one
4, 5-dichloro-2-n-octylisothiazolin-3-one
4,5-trimethylene-2-methylisothiazolin-3 -one
2,2xe2x80x2-dithiodibenzoic acid di-N-methylamide
benzisothiazolinone derivatives
2-thiocyanomethylthiobenzothiazole
C formals, such as
2-hydroxymethyl-2-nitro- 1,3-propanediol
2-bromo-2-nitropropane- 1,3-diol
methylene bisthiocyanate
reaction products of allantoin
3-Iodo-2-propinyl-N-butyl carbamate, 2-n-octylisothiazolin-3-one, formaldehyde or a formaldehyde source material, and 2-bromo-2-nitropropane-1,3-diol are preferred as such other active biocidal substances.
Examples of the formaldehyde source material are N-formals such as
N,Nxe2x80x2-dimethylolurea
N-methylolurea
dimethyloldimethyl hydantoin
N-methylolchloroacetamide
reaction products of allantoin
glycol formals such as
ethylene glycol formal
butyl diglycol formal
benzyl formal
The biocide composition of the invention can also contain other customary constituents known as additives to those skilled in the art in the field of biocides. These are, e.g., thickening agents, defoaming agents, substances to adjust the pH value, perfumes, dispersing agents, and coloring substances.
2-Methylisothiazolin-3-one and 1,2-benzisothiazolin-3-one are known substances. 2-Methylisothiazolin-3-one can be produced, for example, according to U.S. Pat. No. 5,466,818. The reaction product obtained thereby can be purified, e.g., by column chromatography.
1,2-Benzisothiazolin-3-one is commercially available, for example, under the trade name Acticide(copyright) BW 20 and Acticide(copyright) BIT from the company Thor Chemie GmbH.
3-Iodo-2-propinyl-N-butyl carbamate is likewise commercially available, for example, from the Troy Chemical Company under the trade name Polyphase(copyright), Polyphase(copyright) AF-1, and Polyphase(copyright) NP-1, or from Olin Corporation under the trade name Omacide(copyright) IPBC 100.
2-n-Octylisothiazolin-3-one is also commercially available, for example, from the company Thor Chemie GmbH under the trade name Acticide(copyright) OIT.
Finally 2-bromo-2-nitropropane-1,3-diol is commercially available, for example, from the company Boots under the trade name Myacide(copyright) AS.
According to a first embodiment of the invention, the biocide composition of the invention is a system in which the combination of 2-methylisothiazolin-3-one and 1,2-benzisothiazolin-3-one synergistically develops a biocidal activity greater than that exhibited by each of these compounds alone.
Also, in so far as the biocide composition of the invention according to further embodiments of the invention contains, in addition to the two-component combination of 2-methylisothiazolin-3-one and 1,2-benzisothiazolin-3-one, one of the further active biocidal substances 3-iodo-2-propinyl-N-butyl carbamate, 2-n-octylisothiazolin-3-one, formaldehyde or formaldehyde source material, or 2-bromo-2-nitropropane-1,3-diol, a synergistic biocidal activity is achieved greater than that exhibited by the above-mentioned two-component combination and each of these further active substances alone.
When the two-component combination is used together with one of the above-mentioned further active biocidal substances, it contains 2-methylisothiazolin-3-one and 1,2-benzisothiazolin-3-one, preferably in a weight ratio of 1:1. Any other weight ratio can also be selected, however, in so far as a synergistic activity is achieved thereby.
The biocide composition of the invention can be used in very different fields. It is suitable, for example, for use in paints, plasters, lignosulfonates, chalk suspensions, adhesives, photochemicals, casein-containing products, starch-containing products, bituminous emulsions, surfactant solutions, motor fuels, cleaning agents, cosmetic products, water circulating systems, polymer dispersions, and cooling lubricants, against attack by, for example, bacteria, filamentous fungi, yeasts, and algae.
In practice, the biocide composition can be used either as a ready-to-use mixture or by adding the biocides and the remaining components of the composition separately to the substance to be preserved.