Biocide composition and use

Details Biocide composition and use Biocide composition and use

2001-08-23

2002-09-24

Pryor, Alton (Department: 1616)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Having -c-, wherein x is chalcogen, bonded directly to...

Reexamination Certificate

active

06455558

ABSTRACT:

The present invention relates to a biocidal composition comprising a isothiazolinone such as an N-alkyl-isothiazolin-3-one and a metal complex of a cyclic thiohydroxamic acid and its use to inhibit the growth of micro-organisms in a medium which is susceptible to microbiological degradation and especially to inhibit the growth of deteriogens of plastics materials in soil burial conditions.
WO 96/22023 discloses the use of N-(C
3-5
-alkyl)-1,2-benzisothiazolin-3-one as a biocide and especially a fungicide for plastics materials. It has now been found that the antimicrobial activity of these and other isothiazolinones is significantly improved by incorporating a metal complex of a cyclic thiohydroxamic acid.
According to the invention there is provided a method for the preservation of a plastics material which comprises treating the plastics material with a composition comprising (a) an isothiazolinone of formula (1) and (b) a metal complex of a cyclic thiohydroxamic acid.
wherein:
X is C
1
-C
8
-alkyl, C
3-5
-cycloalkyl or aralkyl; and
Y and Z are independently selected from hydrogen, halogen or C
1-4
-alkyl.
Preferably, the halogen is iodine, bromine and especially chlorine.
When X is alkyl it may be linear or branched and is preferably linear.
When X is cycloalkyl, it is preferably cyclopropyl or cyclopentyl.
When X is aralkyl, it preferably contains two or more carbon atoms in the alkylene group attaching the aryl group to the isothiazolinone ring. Preferably the aralkyl group is 2-phenylethyl. Other examples of aralkyl are benzyl and 2-naphthylethyl.
It is particularly preferred that when X is n-octyl Y and Z are either both chlorine or both hydrogen. The preparation of isothiazolinones of this type is disclosed in U.S. Pat. No. 4,105,431.
The cyclic thiohydroxamic acid preferably contains a 5- or 6- membered ring which is optionally substituted. It is preferably a metal complex of a compound of formula 2
wherein
A is a group —C(R
2
)
2
—, —C(R
2
)═or —CR
2
═CR
2
—;
B is a group —C(R
2
)
2
—, —C(R
2
)═or —C(NR
2
)—;
D is a group —C(R
2
)
2
—, —C(R
2
)═, -NR
2
— or sulphur;
R
2
is hydrogen, optionally substituted C
1-6
-hydrocarbyl or two groups R
2
together with the carbon atom to which they are attached form a C
3-6
-hydrocarbon ring or two groups R
2
together with the two carbon atoms to which they are attached form a fused ring.
When R
2
is hydrocarbyl it is preferably alkyl or phenyl and the alkyl group may be branched or preferably linear. It is particularly preferred that R
2
is hydrogen or C
1-4
-alkyl, for example methyl.
When R
2
is substituted, the substituent may be any group or atom which does not significantly adversely affect the microbiological properties of the cyclic thiohydroxamic ring system. Preferred substituents are hydroxy, halogen and nitrile. It is particularly preferred that R
2
is unsubstituted.
When two moieties R
2
together with the carbon atom to which they are attached form a ring, the ring is preferably cyclohexyl.
When two moieties R
2
together with the carbon atoms to which they are attached form a fused ring, the ring is preferably a fused phenyl ring.
When D is sulphur, the compound of formula 2 is preferably a thiazol-2(3H)-thione wherein both A and B are either the group —C(R
2
)
2
— or especially the group —C(R
2
)═.
When D is the group —NR
2
—, the compound of formula 2 is preferably an imidazolidine-2-thione. When D is the group —NR
2
—, it is also preferred that A is the group —C(R
2
)
2
— or —C(R
2
)═and B is the group —C(NR
2
)—.
When D is a group —C(R
2
)
2
— or a group —C(R
2
)═, it is preferred that both A and B are also the groups —C(R
2
)
2
— or —C(R
2
)═. In this case, the compound of formula 2 is preferably a pyrrolinethione, pyrrolidinethione or an isoindolinethione.
When A is the group —CR
2
═CR
2
—, it is preferably the group —CH═CH— and both B and D are the group —C(R
2
)═when the compound of formula 2 is a pyridine-2-thione.
Examples of the compound of formula 2 are:
3-hydroxy-4-methylthiazol-2(3H)-thione,
3-hydroxy-4-phenylthiazol-2(3H)-thione,
3-hydroxy-4,5,6,7-tetrahydrobenzothiazol-2(3H)-thione,
5,5-dimethyl-1-hydroxy-4-imino-3-phenylimidazolidine-2-thione,
1-hydroxy-4-imino-3-phenyl-2-thiono-1 ,3-diazaspiro[4,5]-decane,
1-hydroxy-5-methyl-4-phenylimidazoline-2-thione,
4,5-dimethyl-3-hydroxythiazol-2(3H)-thione,
4-ethyl-3-hydroxy-5-methylthiazol-2(3H )-thione,
4-(4-chlorophenyl)-3-hydroxythiazol-2(3H)-thione,
3-hydroxy-5-methyl-4-phenylthiazol-2(3H)-thione,
1-hydroxypyrrolidin-2-thione,
5,5-dimethyl-1-hydroxypyrrolidin-2-thione,
2-hydroxy-2,3-dihyro-1 H-isoindol-1-thione, and
5 1-hydroxypyridine-2-thione.
The metal which forms the complex of the compound of formula 2 is preferably a metal from Groups IIIA to VA or IB to VIIB or a transition metal of the Periodic Table according to Mendeleef as set out on the inside rear cover of “Handbook of Chemistry and Physics” 49
th
edition (1968-9) published by The Chemical Rubber Co., Cleveland, Ohio, USA. Preferably, the metal is a metal of Group IIB and is especially zinc.
Particularly useful effects have been obtained when the isothiazolinone is either N-n-octyl-isothiazolin-3-one or 4,5-dichloro-N-n-octyl-isothiazolin-3-one and the metal complex of the compound of formula 2 is the 2:1 zinc complex of 3-hydroxy-4-methylthiazol-2(3H)-thione or the 2:1 zinc complex of 1-hydroxypyridine-2-thione. The preparation of the isothiazolinones is described in U.S. Pat No. 4,105,431 and the preparation of the cyclic thiohydroxamic acids is described in EP 249,328 and U.S. Pat. No. 5,120,856. The preparation of metal complexes of 1-hydroxypyridine-2-thione is specifically disclosed in U.S. Pat. No. 2,686,786, U.S. Pat. No. 2,758,116 and U.S. Pat. No. 2,809,971.
The relative proportions of component (a) and component (b) in the composition can vary between wide limits but is preferably from 100:1 to 1:100, more preferably from 10:1 to 1:10 and especially from 3:1 to 1:3, for example about 1:1.
The composition of the present invention has antimicrobial properties and has been found particularly effective against deteriogens for plastics materials, especially in soil burial applications.
The composition according to the invention is useful to inhibit the growth of micro-organisms in a medium which is susceptible to microbiological degradation. Component (a) and component (b) of the composition may be added to the medium either sequentially or preferably simultaneously. Where appropriate, the composition may be added directly to the medium, especially where the medium is a solid such as a plastics material. In other uses, it is more convenient to treat the medium with a composition comprising component (a), component (b) and a carrier.
As noted hereinbefore, the composition according to the invention has been found particularly useful as a biocide for inhibiting the growth of deteriogens for plastics materials, especially organic polymeric material containing a plasticiser or stabiliser.
Examples of plastics materials are polyurethanes, polyvinylhalides such as polyvinylchloride (PVC), polyalkylenes such as polypropylene, polyalkylene vinyl acetate such as polyethylene vinyl acetate, polyester such as polyethyleneterephthalate, polyamide and polyacrylonitrile. The composition has been found especially effective for inhibiting the growth of micro-organisms in or on plasticised PVC. Other suitable plastics materials are caulks and sealants, especially silicone sealants.
The amount of the composition according to the invention which is present in the plastics material may vary over wide limits from a minimum amount which just inhibits microbiological growth up to many times this amount. Thus, where the plastics material containing the composition is to be used as a master-batch for mixing with untreated plastics material the amount of the composition may be two or three magnitudes greater than that required to inhibit microbiological growth. Preferably, the amount of the composition in the plastics material which is

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