Microbiocidal mixtures

Details Microbiocidal mixtures Microbiocidal mixtures

1999-06-09

2001-05-08

Harrison, Robert H. (Department: 1619)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C514S241000, C514S245000, C514S372000

Reexamination Certificate

active

06228382

ABSTRACT:

Coated synthetic or natural materials which are exposed to the weather are quickly colonized by microorganisms (microbes), such as bacteria, mould fungi, yeasts, lichen or algae and damaged by the products of their metabolism. Thus, plasters, for example on insulating layers such as polystyrene panels (integral thermal insulation systems), on exterior facades or in damp locations, such as, for example, swimming pools, quickly change their colour to from green to black, owing to colonization by algae.
When preparing such coating materials, it is therefore customary to add biocides, for example microbiocidaly active substances, i.e. substances which substantially prevent the growth of microorganisms, or biostatics, such as, for example, microbiostatic substances, i.e. substances which only inhibit the growth of microorganisms, to extend the life of said coating materials and, in particular, to ensure a long-lasting high optical quality of the coatings.
Likewise, objects, such as, for example, leather, paper, such as, for example, cardboard boxes, plastics and the like are, when they are in the open and exposed to the action of weather, or when they are used or stored in damp locations, subject to colonization by microorganisms. Such a colonization can not only have a negative effect on the use properties of the abovementioned objects; in general, the optical appeal is affected to a considerably greater extent, a fact which in most cases constitutes a loss in value for the owner of the object in question.
Suitable microbiocides for the microbiocidal finishing of the abovementioned objects and coating materials are, for example, tributyltin compounds, 2-n-octylisothiazoli-none, carbendazim, 2-thiocyanatomethylthiobenzothiazole, terbutryn or diuron.
However, it has been found that the substances which have hitherto been used for microbiocidal finishing cannot ensure a long-lasting protection against colonization. Most of the microbicides known from the prior art are, under the influence of moisture, leached out from the objects which are finished with them. This results in a continuous decrease of the microbiocidaly active compound in the object in question, whose protection against colonization by microbes therefore approaches zero within a longer or shorter period of time (depending on the exposure to moisture). Another associated disadvantageous aspect is the high discharge of the microbiocides into the environment.
Microbiocides which are frequently used in practice include the isothiazolin-3-ones which are substituted in the 2-position, in particular 2-n-octylisothiazolin-3-one. It is employed for a number of substances and objects which are, for example during use and storage outdoors or in damp locations, subject to colonization by microbes, such as, for example, algae, lichen, fungi and the like. One use example is paint for facades.
The patents U.S. Pat. No. 3,523,121, U.S. Pat. No. 3,761,488 and U.S. Pat. No. 4,243,403 describe the preparation and the microbicidal properties of 2-alkylisothiazolinones including, inter alia, 2-n-octyl-, 2-n-nonyl- and 2-n-decylisothiazolin-3-one. However, in these publications, no statements are made concerning the leaching behaviour of the compounds and their combination with other biocides, in particular microbiocides.
The compounds which have hitherto been used as microbiocides often, when used on their own, have an incomplete activity spectrum. In practice, use is therefore frequently made of combinations of a plurality of microbiocides, to achieve an activity spectrum that is as wide and as comprehensive as possible.
Products which, in addition to 2-n-octylisothiazolin-3-one, comprise other fungicidally and algicidally active compounds (for example MERGAL® S 89 paste and MERGAL® S 90 paste) are commercially available.
However, here it is disadvantageous that, in general, some of the 2-n-octylisothiazolin-3-one is leached out under the influence of moisture (for example, in the case of outdoor applications) from the object that has been finished with it, and is thus withdrawn from the active compound combination. This results in a “gap” in the microbiocidal protection, and colonization by corresponding microbes may occur.
It was therefore the object to provide microbiocides which meet the following requirements:
a) a microbiocidal activity spectrum which is as wide as possible, where the fungicidal activity should, if possible, also cover fungi which are particularly resistant towards fungicides, such as, for example, fungi of the order Alternaria, Mucor or Ulocladium, or yeasts,
b) have a low tendency for leaching out from the microbiocidaly finished objects and substances.
The object was, in particular, to provide a replacement for 2-n-octylisothiazolin-3-one in microbiocidal mixtures which has a comparable microbiocidal activity but which is leached out to a lesser extent.
Surprisingly, it has now been found that mixtures of 2-alkylisothiazolin-3-ones which have an octanol/water partition coefficient (logPow) of from 3 to 5 and other microbiocidal compounds exhibit a long-lasting activity against microorganisms in objects finished with them. Furthermore, the abovementioned mixtures have a wide activity spectrum against microorganisms and offer comprehensive protection against colonization by yeasts, fungi, algae and lichen.
Furthermore, it has surprisingly been found that the 2-alkylisothiazolin-3-ones in a mixture with one or more algicides are suitable for incorporation into materials such as, for example, plastic, leather, paper, wood, a sealant or a coating material, both water-based and solvent-based, and that they exert a long-lasting microbiocidal effect therein.
Furthermore, it has surprisingly been found that the known fungicidal activity of the 2-alkylisothiazolin-3-ones also covers fungi such as, for example, Alternaria, Mucor or Ulocladium which are very resistant towards fungicides and also yeasts which may grow in particular in food-processing plants, for example on wall coatings which have been finished with conventional fungicides.
The invention therefore provides a mixture comprising as active substance
a) 0.01 to 99.99% by weight of at least one 2-alkylisothiazolin-3-one or at least one derivative thereof or a mixture of at least one 2-alkylisothiazolin-3-one and at least one derivative thereof and
b) 0.01 to 99.99% by weight of at least one other, microbiocidaly active compound
where the sum of a) and b) is 100% by weight of the active substance of the mixture, characterized in that the at least one 2-alkylisothiazolin-3-one or the at least one derivative thereof has an octanol/water partition coefficient (logPow) of from 3 to 5.
For the purpose of the invention, “active substances” are those substances present in the mixture which show microbiocidal activity.
For the purpose of the invention, “derivatives” are compounds whose chemical skeleton (i.e. the moiety responsible for the basic generic activity of the compound) is identical with that of the originally defined compound, but which have been chemically modified to improve, adapt or change a biological, chemical or physical property in another way. Accordingly, a derivative of a 2-alkylisothiazolin-3-one, for example, may be a 2-alkylisothiazolin-3-one which is substituted in the 4-position by a halogen. Further derivatives of the 2-alkylisothiazolin-3-one are mentioned in the patents U.S. Pat. No. 3,523,121, U.S. Pat. No. 3,761,488 and U.S. Pat. No. 4,243,403.
The term “octanol/water partition coefficient” denotes the logarithm to base ten of the partition coefficient between n-octanol and water.
The mixture according to the invention preferably comprises approximately 1 to approximately 99% by weight, furthermore preferably approximately 2 to approximately 98% by weight, of at least one 2-alkylisothiazolin-3-one or at least one derivative thereof or a mixture of at least one 2-alkylisothiazolin-3-one and at least one derivative thereof (component a)).
2-Alkylisothiazolin-3-ones which can be employed for the purpose of the invention have an octanol/water pa

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