Aqueous fungicide dispersion

Details Aqueous fungicide dispersion Aqueous fungicide dispersion

2001-09-26

2003-01-14

Pryor, Alton N. (Department: 1616)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

N-c doai

C514S478000, C514S479000

Reexamination Certificate

active

06506794

ABSTRACT:

This application is the National Phase of International Application PCT/GB00/00979 filed Mar. 16, 2000 which designated the U.S. and that International Application was.
The present invention relates to a stable aqueous dispersion of a halopropynyl compound and to its use in inhibiting the growth of micro organisms such as fungi and algae on or in a medium, especially an industrial medium.
Halopropargyl compounds (hereinafter HPC's) are well-known fungicides and the most widely used is 3-iodo-2-propynyl-N-n-butylcarbamate (herein after IPBC). IPBC is available commercially in both solid form and as a liquid concentrate in organic solvents.
During the last few years there has been an increasing demand for industrial biocide formulations which contain low levels of volatile organic compounds (hereinafter low VOC) and particularly a demand for wholly aqueous formulations. Hitherto, this has been difficult to achieve in the case of HPC's such as IPBC because of their low but significant aqueous solubility. Because of this low solubility in water there is a tendency for small particles to dissolve and to be deposited on larger particles. There is, thus, a tendency for the particle size distribution of the aqueous dispersion to change on storage to fewer particles of larger size. This coarsening of the particle size is referred to as “Ostwald ripening” as discussed, for example, in “Crystallisation” by J. W. Mullin, 3
rd
edition, published by Butterworth/Heinemann, paperback edition 1997, pages 288 to 290. This Ostwald ripening manifests itself in instability of the aqueous dispersion, especially under adverse storage conditions and results in layering and sedimentation of the HPC.
We have examined a number of dispersants of both the non-ionic and anionic type which are designed for distributing particulate solids in an aqueous medium. None of those examined have resulted in stable aqueous dispersions of the HPC. However, we have now found that one class of dispersant which exhibits weak surface-active properties does result in aqueous dispersions of HPC's with surprisingly good storage stability especially under freeze/thaw conditions. These dispersants are partially hydrolysed polyvinyl alcohols (hereinafter PHPVA).
According to a first aspect of the present invention there is provided an aqueous dispersion comprising a HPC and a PHPVA.
Preferably, the HPC is a compound of formula 1
wherein
Y is halogen;
R
1
and R
2
are each, independently, C
1-6
-alkyl, C
2-6
-alkenyl or C
3-7
-cycloalkyl;
m is from 1 to 6; and
X is an organic moiety linked to the —CR
1
R
2
— group via an oxygen, nitrogen, sulphur or carbon atom.
Preferably, Y is chlorine, bromine and especially iodine. The compound of formula 1 wherein Y is iodine is an iodopropargyl compound (hereinafter IPC).
The organic moiety linked to the —CR
1
R
2
— group via an oxygen, nitrogen, sulphur or carbon atom preferably contains not greater than 20 and especially not greater than 10 carbon atoms.
The compound of formula 1 wherein the organic moiety is linked to the group —CR
1
R
2
— via an oxygen atom is preferably an ether, ester or especially a carbamate.
The compound of formula 1 wherein the organic moiety is linked to the group —CR
1
R
2
— via a nitrogen atom is preferably an amine or amide.
The compound of formula 1 wherein the organic moiety is linked to the group —CR
1
R
2
— via a sulphur atom is preferably a thiane, sulphone or sulphoxide.
The organic moiety can be alkyl, alkenyl, aryl, heteroaryl, aralkyl, cycloalkyl or cycloalkenyl, all of which may be optionally substituted. When the organic moiety is alkyl, it may be linear or branched but is preferably linear.
Optional substituents in the organic moiety are halogen (preferably chlorine, bromine or iodine), C
1-6
-alkyl and C
1-6
-alkoxy.
Preferably, R
1
and R
2
are both hydrogen.
Preferably m is one.
According to a first preferred embodiment of the invention the IPC is a compound of formula 2
wherein
R is hydrogen, optionally substituted C
1-20
-alkyl, optionally substituted C
2-20
-alkenyl, optionally substituted aryl, optionally substituted aralkyl, C
3-20
-cycloalkyl or C
3-20
-cycloalkenyl; and
n and p are each, independently, from 1 to 3.
When R is C
1-20
-alkyl it is preferably C
1-8
-alkyl or more preferably C
1-6
-alkyl. The alkyl group may be linear or branched. Examples are methyl, ethyl, propyl , sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, octadecyl and especially n-butyl.
When R is aryl, it is preferably phenyl.
When R is aralkyl, it is preferably 2-phenylether or benzyl.
When R is cycloalkyl, it is preferably C
4-7
-cycloalkyl, more preferably cyclopropyl or cyclohexyl.
When R is cycloalkenyl, it is preferably cyclohexenyl.
Preferred optional substituent(s) carried by R include halogen (preferably chlorine, bromine or iodine), C
1-6
-alkyl or C
1-6
-alkoxy. It is preferred, however, that R is unsubstituted.
Preferably n is one. Preferably p is one.
The IPC's of formula 2 are disclosed in U.S. Pat. No. 3,923,870; U.S. Pat. No. 4,259,350; U.S. Pat. No. 4,592,773; U.S. Pat. No. 4,616,004; U.S. Pat. No. 4,719,227 and U.S. Pat. No. 4,945,109.
Especially preferred IPC's of formula 2 are 3-iodo-2-propynyl-N-n-propyl carbamate, 3-iodo-2-propynyl-N-n-butylcarbamate, 3-iodo-2-propynyl-N-n-hexyl carbamate, 3-iodo-2-propynyl-N-cyclohexylcarbamate and 3-iodo-2-propynyl-N-phenyl carbamate.
According to a second aspect of the invention, the IPC is a compound of formula 3
wherein:
R is defined hereinbefore;
R
1
and R
2
are each, independently, C
1-6
-alkyl, C
2-6
-alkenyl, C
3-7
-cycloalkyl or —CR
1
R
2
— represents (—CH
2
)
t
— where t is from 4 to 6; and
R
3
to R
6
are each, independently, hydrogen, C
1-4
-alkyl, aryl, —CCI
3
or R
3
with R
5
or R
4
with R
6
represents —(CH
2
)
q
— where q is from 3 to 5.
The preparation of IPC's of formula 3 are described in, for example U.S. Pat. No. 4,474,807.
Especially, preferred IPC's of formula 3 are 2-(3-iodo-2-propynyloxy)-ethyl-N-methylcarbamate, 2-(3-iodo-2-propynyloxy)-ethyl-N-n-butylcarbamate, 2-(3-iodo-2-propynyloxy)-ethyl-N-phenylcarbamate and 2-(3-iodo-2-propynyloxy)-ethyl-N-(4-chlorophenyl)carbamate.
It is especially preferred that the aqueous dispersion contains an IPC of formula 2 and that the IPC of formula 2 is IPBC.
The PHPVA is preferably obtainable from a polyvinyl ester of an organic acid where the organic acid contains from 1 to 6 carbon atoms excluding the carbonyl carbon atom. Typically the PHPVA is obtainable by partial hydrolysis of the polyvinyl ester of the organic ester, for example by saponification using a suitable base such as KOH or NaOH. Thus, the PHPVA contains both hydroxy groups and C
1-6
-hydrocarbyl-carbonyl radicals. It is preferred that the organic acid is acetic acid whereby the PHPVA is a partially hydrolysed polyvinyl acetate.
Preferably, a 4% aqueous solution of the PHPVA has a viscosity from 2.5 to 42, more preferably from 5 to 27.5 and especially from 7 to 24.5 mPa.s at 20° C. as determined, for example, using DIN 53015.
It is also preferred that the degree of hydrolysis of the partially hydrolysed polyvinyl ester of the organic acid is from 71 to 89 (more preferably from 71.6 to 88.7) mole %.
The ester value of the PHPVA is preferably from 80 to 280 mg KOH/gm, more preferably from 130 to 210 mg KOH/gm and especially from 130 to 150 mg KOH/gm. The ester value refers to the number of mg of KOH required for the neutralisation of the acid released by saponification of 1 g of PHPVA
In the case of PHPVA which is derived from polyvinyl acetate, the residual acetyl content is preferably from 7.1 to 22% by weight and especially from 10 to 11.6% by weight.
The amount of HPC in the aqueous dispersion is preferably not less than 1%, more preferably not less than 5% and especially not less than 10% by weight of the total amount of the dispersion. It is also preferred that the amount of HPC is not greater than 60%, more preferably not greater than 50% and especially not greater than 30% by weight based on the total a

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