Insecticide formulations

Details Insecticide formulations Insecticide formulations

1998-12-28

2001-01-09

Harrison, Robert H. (Department: 1617)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S040000, C424S409000, C514S531000

Reexamination Certificate

active

06171608

ABSTRACT:

The present invention relates to novel liquid formulations for the controlled and sustained release of insecticidally active compounds by means of a heat source and the pre-solutions required for preparing these formulations. The novel insecticidal formulations for the controlled and sustained release of insecticidally active compounds are characterized in that they comprise transfluthrin as insecticide and more than 90% of water as solvent.
Electrical heating devices, for example so-called tablet vaporizers, for killing insects, for example mosquitos, are known from the prior art. In this method, suitable materials, such as, for example, pulp and cotton cardboard, asbestos, ceramic and/or porous artificial resins are impregnated with insecticidally active compound solutions to obtain insecticide tablets. The insecticides are volatilized by the action of a heating device generating temperatures of 120-190° C.
A considerable disadvantage of these tablet vaporizers is the unfavorable ratio of energy input to amount of active compound to be vaporized, since the proportion of active compound in relation to the auxiliaries is low. Furthermore, owing to factors inherent in the system, i.e. the high operating temperature and the mode of action of these vaporizers, the active compounds are released in a very nonuniform manner over the prescribed duration of action. The duration of action of these vaporizer tablets is limited to a maximum of 12 hours. Finally, the unfavorable ratio of active compound to active compound carrier permanently requires a relatively large supply of vaporizer tablets, resulting in a considerable consumption of material.
Vaporizing devices for domestic use as described in GB 2 153 227, where the vaporization of an insecticidally active compound solution is effected by means of a heated wick and where the active compound is dissolved in a mixture of saturated aliphatic hydrocarbons which is vaporized electrically by using the wick, have been known for some time.
The amount of organic solvent required in these so-called liquid vaporizers, which is considerable in relation to the amount of active compound, results in a high indoor solvent concentration when the product is used.
This in turn causes walls and objects in the vicinity of these devices to become soiled, which is often complained about by users.
A decisive disadvantage of the formulations used in these devices is the fact that their use leads to permanently high concentrations of organic substances, such as saturated hydrocarbons, in the room air, which, for health reasons, is becoming less and less desirable.
A further disadvantage of these formulations is the risk of the flammable solvents leaking, leading to considerable problems during transport and storage and hazards during use.
The object of the present invention was to formulate insecticidally active compounds in such a way that they are not only storage-stable but can also, in addition to this, be vaporized undecomposed in combination with organic and inorganic auxiliaries, emulsifiers, solublilizers, stabilizers, antioxidants, perfumes and colorants from physiologically acceptable solutions in a uniform way and over a prolonged period by means of a heat source. The vaporization is to be carried out using a commercially available vaporizing device where a physiologically acceptable solution is absorbed by a suitable wick and released into the atmosphere by heating the upper part of this suitable wick.
The present invention thus relates to liquid formulations for vaporization using electric vaporizers fitted with a wick not having the disadvantages of the prior art owing to water being used as solvent. Since water is used as solvent, the formulations according to the invention are not flammable, and organochemical substances are released into the room air to a much lesser extent. This method for vaporizing an aqueous insecticidal solution can be employed for killing insects, such as, for example, mosquitos or moths.
In addition, the aqueous formulations according to the invention are simple to use in commercially available liquid vaporizers at the normal vaporizing temperatures of 100 to 160° C., and they ensure a continuous release of the active compound for up to 60 days, preferably up to 45 days.
The formulations according to the invention include formulations comprising insecticides, for example transfluthrin, water as solvent and one or more organochemical substances suitable as emulsifiers and/or co-surfactant. In addition, organic or inorganic auxiliaries, stabilizers, perfumes and/or colorants can be added to the mixtures.
The formulations according to the invention are prepared for example by initially preparing a pre-solution of transfluthrin, emulsifier and, if appropriate, co-surfactant which is then diluted to the desired emulsion volume by vigorous mixing with small portions of water. Further additives, perfumes and colorants can be admixed either to the pre-solution or to the ready-made-up diluted emulsion.
Alternatively, the formulations according to the invention can be obtained by directly mixing the individual components in succession.
The active compound transfluthrin is particularly suitable for the formulations according to the invention and applications thereof since it can be emulsified particularly well in the manner stated and in addition possesses the high thermal stability necessary for the application, so that, during vaporization, no decomposition products interfering with the transport process through the wick and the vaporization from the upper end of the wick are formed.
Other active compounds, such as, for example, d-allethrin or bioallethrin, which are conventionally used in liquid vaporizer systems have long been known to be poorly emulsifiable and to have the tendency to decompose when heated and to form decomposition products blocking the wick.
Suitable emulsifiers are, for example:
nonionic emulsifiers, such as reaction products of unsubstituted or substituted phenols, respectively optionally unsaturated or saturated fatty alcohols, fatty acids, fatty acid alkanolamides or fatty amines, vegetable oils or fats, partial fatty acid esters of polyols with ethylene oxide and, if appropriate, propylene oxide, sorbitan esters of fatty acids, fatty acid esters of polyols such as sucrose, glucose or sorbitan,
anionic emulsifiers, such as respectively optionally saturated or unsaturated alkanesulfonates, alkyl sulfates, alkyl phosphates, alkyl ether sulfates, alkyl ether phosphates, salts of fatty acids, alkyl ether carboxylates, acyltaurides or acylsarcosides, each of which contains 8 to 22 carbon atoms,
cationic emulsifiers, such as amine salts, quaternary ammonium compounds or imidazolinium compounds, each of which contains 8 to 22 carbon atoms,
amphoteric emulsifiers, such as betaines, sulfobetaines or amine oxides, each of which contains 8 to 22 carbon atoms.
Preferred emulsifiers are:
reaction products of 4-50, in particular 8-30, mol of ethylene oxide and, if appropriate, propylene oxide with phenols (1 mol) substituted by one or more radicals (C
1
-C
12
)-alkyl, (C
3
-C
6
)-cycloalkyl-, phenyl-, phenyl-(C
1
-C
3
)-alkyl-, or methylphenyl-(C
1
-C
3
)-alkyl and reaction products of 5-50, in particular 8-30, mol (per equivalent of fatty radical) of ethylene oxide and, if appropriate, propylene oxide with (C
10
-C
22
)-fatty alcohols, fatty acids or fatty acid glycerides.
The aqueous formulations may additionally preferably also comprise alkali metal salts and/or alkaline earth metal salts of (C
10
-C
20
)-alkanesulfonic acids, in particular dodecylbenzenesulfonic acid, as further emulsifiers.
Particular preference is given to the following emulsifiers, which can be used on their own or in a mixture:
Emulsifier 1371 A (67% of alkylarylsulfonate, 23% of n-butanol, CAS # 90 194-26-6), a linear calcium arylsulfonate dissolved in n-butanol:
Emulsifier 1371 B (100% of fatty acid polyethylene glycol ether esters, CAS # 61791-12-6), a reaction product of castor oil with 20-40 mol of ethylene oxide,
Emulsifier

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