Controlled release compositions

Details Controlled release compositions Controlled release compositions

2001-03-19

2004-01-13

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S076600, C424S076500, C424S408000, C424S409000, C424S400000, C514S372000, C514S373000

Reexamination Certificate

active

06676954

ABSTRACT:

BACKGROUND
This invention relates to solid compositions of biocidal compounds that provide controlled release of the biocidal compounds, in particular, the controlled release of certain water-insoluble 3-isothiazolone compounds.
The ability to control the release of 3-isothiazolone compounds to a locus to be protected is important in the field of biologically active compounds, especially in the field of microbicides and marine antifouling agents. Typically, when a 3-isothiazolone compound is added to a locus to be protected, the compound is rapidly released, whether or not it is needed. Controlled release compositions deliver the 3-isothiazolone compound in a manner that more closely matches the need for the compound, that is, only the amount of the 3-isothiazolone compound actually needed is released into the locus to be protected. Controlled release offers the advantages of reduced cost, lowered toxicity and increased efficiency.
Solid formulations of 3-isothiazolone compounds are a useful method of delivering 3-isothiazolone compounds to a locus to be protected. Solid formulations also offer the advantage of safening the 3-isothiazolone compound by reducing the possibility of human exposure. For example, solid compositions eliminate the splash hazard that is common with liquid compositions.
Various solid compositions of 3-isothiazolone compounds are known. Such compositions include encapsulation of the 3-isothiazolone compound, adsorption of the 3-isothiazolone compound on an inert carrier such as silica gel, and clathration of the 3-isothiazolone compound. However, such solid compositions do not always provide controlled release of the 3-isothiazolone compounds. For example, solid compositions where the 3-isothiazolone compound is adsorbed on an inert solid carrier usually do not control the release of the 3-isothiazolone compound. Typically, once such a solid composition is added to a locus to be protected, the 3-isothiazolone compound is rapidly released. Thus, any safening of the 3-isothiazolone compound provided by the solid composition is lost once the composition is added to the locus.
For example, EP 106563 A discloses microbicidal compositions having a water-soluble microbicide admixed with an inert, finely-divided, water-insoluble solid carrier, such as clays, charcoal, inorganic silicates and silicas. These compositions do not provide controlled release of the 3-isothiazolone compounds. The compounds release into the locus by dissolution, and therefore, their release is controlled by the dissolution rate of the particular 3-isothiazolone compound. Similarly, U.S. Pat. No. 4,505,889 discloses microbicidal compositions having microbicide with low water-solubility admixed with an inert, finely-divided, water-insoluble solid carrier, such as clays, inorganic silicates and silicas. JP 63-35504 discloses controlled release sulfonylurea herbicide granules containing a mixture of activated carbon, paraffin wax and mineral based carrier, such as clay or diatomaceous earth. JP 59-227802 discloses an insecticidal resin composition containing an insecticide, a natural or synthetic resin (such as wax, polyethylene or polypropylene) and a porous substance (such as zeolites or activated carbon) to retain the insecticide. WO 96/38039 discloses controlled release pesticide compositions containing activated carbon and adsorbed pesticides, such as insecticides, herbicides or fungicides.
The problem addressed by the present invention is to provide solid compositions of 3-isothiazolone compounds that are safer to handle and provide controlled release of 3-isothiazolone compounds once the composition is added to a locus to be protected.
STATEMENT OF INVENTION
The present invention provides a solid composition comprising a 3-isothiazolone compound having low water solubility and a carbon-based adsorbent, wherein the composition provides controlled release of the 3-isothiazolone compound.
In a preferred embodiment, the invention provides a solid composition wherein the 3-isothiazolone compound is selected from one or more of 2-n-octyl-3-isothiazolone, 4,5-dichloro-2-n-octyl-3-isothiazolone, 4,5-dichloro-2-benzyl-3-isothiazolone and 2-benzyl-3-isothiazolone.
In another aspect, the present invention provides a method for controlling the growth of bacteria, fungi, algae and marine fouling organisms comprising introducing to a locus to be protected the solid composition described above. In particular the invention provides a method for controlling growth of the aforementioned organisms wherein the locus to be protected is selected from one or more of paints, coatings and marine structures.
DETAILED DESCRIPTION
We have discovered that solid compositions useful for providing the controlled release of 3-isothiazolone compounds can be prepared by combining selected 3-isothiazolone compounds having low water solubility with a carbon-based adsorbent. In particular, we have discovered that specific 3-isothiazolones combined in specific relative proportions with carbon-based adsorbents unexpectedly provides the controlled release compositions of the present invention.
As used throughout the specification, the following terms shall have the following meanings, unless the context clearly indicates otherwise. “Microbicide” refers to a compound capable of inhibiting the growth of or controlling the growth of microorganisms in a locus. The term “locus” does not include pharmaceutical or veterinary applications. The term “microorganism” includes, for example, fungi, bacteria and algae. “Marine antifouling agent” includes algaecides and molluscicides. “Marine antifouling activity” is intended to include the elimination of and inhibition of growth of marine organisms. Marine organisms controlled by marine antifouling agents suitable for use in this invention include both hard and soft fouling organisms. Generally speaking, the term “soft fouling organisms” refers to plants and invertebrates, such as slime, algae, kelp, soft corals, tunicates, hydroids, sponges and anemones; and the term “hard fouling organisms” refers to invertebrates having some type of hard outer shell, such as barnacles, tubeworms and molluscs.
As used herein, the term “low water solubility,” as applied to the 3-isothiazolones, means that the 3-isothiazolone is characterized by having a water solubility of less 1000 ppm (0.1%), preferably less than 500 ppm (0.05%) and more preferably less than 100 ppm (0.01%).
Unless otherwise specified, ranges listed are to be read as inclusive and combinable, temperatures are in degrees centigrade (° C.) and references to percentages (%) are by weight. As used throughout this specification, the following abbreviations are applied: g=grams, mL=milliliter, ppm=parts per million (weight/weight) and mm=millimeter.
Suitable 3-isothiazolones useful in the present invention are those isothiazolones having low water solubility and are represented by the formula:
wherein:
Y is an unsubstituted or substituted (C
7
-C
18
)alkyl group, an unsubstituted or substituted (C
7
-C
18
)alkenyl or alkynyl group, an unsubstituted or substituted (C
7
-C
12
)cycloalkyl group, an unsubstituted or substituted (C
7
-C
10
)aralkyl group, or a substituted (C
7
-C
10
)aryl group;
R and R
1
are independently hydrogen, halogen or (C
1
-C
4
)alkyl groups; or
R and R
1
can be taken together with the C═C double bond of the isothiazolone ring to form an unsubstituted or substituted benzene ring.
By a “substituted alkyl group” is meant an alkyl group having one or more of its hydrogens replaced by another substituent group; examples include hydroxyalkyl, haloalkyl and alkylamino. By a “substituted aralkyl group” is meant an aralkyl group having one or more of its hydrogens on either the aryl ring or the alkyl chain replaced by another substituent group; examples include halo, (C
1
-C
4
)alkyl, halo-(C
1
-C
4
)alkoxy and (C
1
-C
4
)alkoxy. By a “substituted aryl group” is meant an aryl group, such as phenyl, naphthyl or pyridyl groups, having one or more of its hydrogens on the aryl ring replaced by a

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