Microemulsion insect control compositions

The present invention relates to microemulsions which kill insects without the use of conventional insecticides. They are especially suitable for killing creeping insects with a hard waxy outer coating.

Hydrocarbon solvents kill insects. Unfortunately, many hydrocarbons are flammable and as a result, conventional insecticides are sometimes included in oil / water type emulsions; see, for example, U.S. Pat. 5,145,604. The material described in this patent and all publications cited therein are incorporated herein by reference.

However, many oil / water emulsions known in the art are unstable. To obtain a stable emulsion, the user must shake the container immediately before use. This results in the formation of more stable emulsions consisting of water, hydrocarbon, conventional insecticide and one or more emulsifiers; see, for example, U.S. Pat. 5,037,653. In the present invention, a "microemulsion" is referred to as a clear, stable oil-in-water dispersion in which the dispersed phase consists predominantly of particles having a diameter of 10 to 100 millimeters.

However, since such state-of-the-art insecticides contain conventional insecticidal active substances, their use must be strictly controlled, relatively expensive, restricted in use (for example, not too close to food), and sometimes treated as environmentally undesirable. .

Attempts have been made to use surfactant solutions directly on insects as a more natural use of insecticides; see, for example, U.S. Pat. No. 5,489,443. However, this technique is not very effective against hard-coated insects such as cockroaches.

Thus, there is a need for better, environmentally safe insect killing compositions.

One aspect of the invention is a microemulsion. The total amount of hydrocarbon in the microemulsion is 20 to 60% by weight. If a hydrocarbon dispersant is used, it is present in the hydrocarbon solvent and is present in an amount of 15 to 35% by weight of the total microemulsion, excluding the dispersant. Ideally, the microemulsion is capable of "knocking down" at least 80% of the black cockroaches in one minute or less under the standard assay conditions described below.

The surfactants in the microemulsion are from 1 to 20% by weight, and at least 10% by weight of the microemulsion is water (preferably above 30%). Most importantly, the microemulsion is substantially free of conventional insecticidal active substances as defined below.

The aerosol form of the microemulsion described above is preferred. It is preferred that 5% or more (e.g. 10-25%) by weight of the microemulsion is a hydrocarbon dispersing agent dispersed in the microemulsion.

A wide variety of gaseous hydrocarbons can be used for this purpose. Typically, they are liquefied to form part of a hydrocarbon solvent under pressure in an aerosol dispenser. For example, the dispersing agent may be dimethyl ether, difluoroethane, propane, butane, isobutane and mixtures thereof. Particular preference is given to the dispersion agent B-70 from Philips Petroleum, which is a propane / n-butane / isobutane mixture in a ratio of 55/27/18 mol%. Another such is the A-70 from Philips Petroleum, a 45/55 mol% propane / isobutane mixture. As used herein, the term "hydrocarbon" refers to a compound consisting of carbon and hydrogen only.

In addition to dispersing agents, a variety of other hydrocarbon solvents may be used. Non-dispersible hydrocarbons having from 6 to 20 carbon atoms are preferred. Examples include hexane, benzene, toluene, xylene, white spirit, oil, d-limonene, naphtha, kerosene, paraffins and other alkanes and alkenes. Particular preference is given to EXXSOL hydrocarbons from Exxon / Esso. These are typical mixtures of hydrocarbons having less than 20 C atoms. The EXXSOL D-95 and EXXSOL D-60 are particularly preferred.

Surfactants may be cationic, anionic, amphoteric, and nonionic. However, we prefer a mixture of anionic and nonionic surfactants; see EP 677579.

Particularly preferred is a mixture of equal parts of isopropylamine sulfonate (Calimulse PRS; Pilot Chemical) and tristyrylphenol such as tristyrylphenol ethoxylate (Soprophor BSU; Rhone Poulenc). Other suitable nonionic surfactants are Soprophor 4D 384 and FL, and polyethoxylate derivatives of primary and secondary alcohols having from 8 to 24 carbon atoms in the alkyl chain of the alcohol. In addition, all or part of the ethylene oxide may be replaced by propylene oxide.

Still other suitable nonionic detergents are polyoxyalkylene alkylphenols; polyalkylene esters of higher organic acids having 8 or more carbon atoms in the hydrophobic portion of the acid and 10 or more moles of ethylene oxide as the hydrophilic group; polyalkylene alkylamines having hydrophobic groups derived from primary, secondary or tertiary amines and having sufficient ethylene oxide to provide both water solubility and nonionic characteristics, typically derived from fatty acids having 8 or more carbon atoms; polyalkylenealkylamides having hydrophobic groups derived from the amide or ester of fatty acids; glycol esters of fatty acids, polyalkylene oxide block copolymers, and the like.

Examples of suitable anionic surfactants are alkylaryl sulfonates having from 6 to 20 carbon atoms in the alkyl group; C₁₀-C₁₂fatty acid soaps; C 10 -C₁₂ sulfates; C₁₀-C₁₂ alkyl sulphonates, including alkali salts of higher alkyl and paraffinic sulphonic acids; alkali metal dialkyl sulfosuccinates, ethoxylated alcohol sulfates, phosphate esters, taurates and the like. For other surfactants see Ref. U.S. Pat. 5,037,653.

As used herein, the term "conventional insecticidally active agent" means an insecticidally active synthetic pyrethroid (e.g., cypermethrin, cyfluthrin, liambda-cyhalothrin, aletrin forte, phenanthrine, dphenanthrin, tetramethrin, resmethrin, esbiotrine, aletrin, , natural pyrethrum (e.g. pyrethrins), organic phosphates (e.g. chlorpyrifos), carbamates (e.g. Baygon) and chlorinated hydrocarbons (e.g. methoxychloro derivatives) and heterocycles (such as phenylpyrroles).

Alcohols may be used as co-solvents to obtain acceptable product characteristics with relatively low emulsifier contents. Ideally, a mixture of primary organic alcohols is added. These can be primary aliphatic alcohols having from 3 to 12 carbon atoms (for example, 1-octanol (Alfol 8), 1-hexanol, 1-pentanol or 1-butanol). Non-aromatic ether alcohols having less than 20 carbon atoms may also be present (e.g., diethylene glycol monohexyl ether (hexylcarbitol), diethylene glycol monobutyl ether or propylene glycol mononobutyl ether). Some glycols such as hexylene glycol, triethylene glycol or 1,4-butanediol may also be added.

The microemulsion can be sprayed from an aerosol dispenser when pressurized and containing a gaseous dispersant. Alternatively, a nebulizer (without a dispersing agent) may be used. The spray current is preferably directed directly at the insect creeping on. Because of its microemulsion spray, it is very stable. This way, it is enough to shake the aerosol at the factory and the user will not have to shake the dispenser before use.

The hydrocarbon helps the emulsifier to penetrate the insect's outer shell. The emulsifier can then more effectively deflate and kill the insect. The size of the particles forming the microemulsion is very important in helping to penetrate the insect shell.

Because of its high hydrocarbon content, the microemulsion has excellent destructive properties. In addition to its high hydrocarbon content, flammability is reasonably low.

Deionized water (for example 20-50% by weight) is preferred. Other standard additives such as corrosion inhibitors and fragrances may also be used.

Ideally, the pH of the microemulsion is from 6 to 8. Too low a pH can cause corrosion and adversely affect the surfaces on which the microemulsion is sprayed.

Insects that are killed by the microemulsion include cockroaches (such as black, brown cockroaches), ants, scales, and other reptile insects.

The object of the present invention is to provide an insecticide:

(a) which does not contain a conventional insecticidal active substance;

(b) which does not need to be shaken by the consumer before consumption;

(c) which is active against creeping insects such as cockroaches;

(d) is relatively cheap;

(e) suitable for aerosol application;

(f) can be used even near food.

These and other objects and advantages of the present invention (for example, the use of such microemulsions) will be apparent from the following description. The description only shows the preferred embodiments. Thus, for the sake of clarity of the entire scope of the invention, the definition must be read.

Detailed Description of the Invention

Experimental preparations

<td>The Ingredient (by weight)</td><td>Microemulsion A</td><td>Microemulsion B</td><td>Microemulsion C</td>

<td>Hydrocarbon solvent</td><td>25% Exxsol D-95</td><td>25% Exxsol D-95</td><td>25% Exxsol D-95</td>

<td>Anionic Surface activity substance</td><td>2% Calimulse PRS</td><td></td><td>2% Calimulse PRS</td>

<td>Cationic surfactant activity substance</td><td></td><td>3% Variquat K-300</td><td></td>

<td>Nonionic superficial activity substance</td><td>2% Soprophor BSU</td><td>2% Soprophor BSU</td><td>2% Soprophor BSU</td>

<td>Co-solvent</td><td>8% hexylcarbitol</td><td>8% hexylcarbitol</td><td>8% hexylcarbitol</td>

<td>Co-solvent</td><td>1.4% 1-octanol</td><td>1.2% 1-octanol</td><td>1% 1-octanol</td>

<td>Dispersant</td><td>18% B-70</td><td></td><td>18% B-70</td>

<td>Deionized water</td><td> 43,20 %</td><td> 60,8 %</td><td> 43,55 %</td>

<td>Flavoring</td><td> 0,15%</td><td></td><td> 0,15 %</td>

<td>Corrosion inhibitor</td><td>0.25% Elfugin AKT</td><td></td><td>0.25% Elfugin AKT</td>

Standard study on creeping insects

To investigate the efficacy of formulations AC (A and B are formulations of the present invention, C is a macroemulsion), we performed a direct-jet test. In one series of experiments (Standard Study), seven-week-old male black cockroach males were housed in a clean, greasy Lucite ring (5 cm high and 10 cm diameter) with an aluminum sieve (6x7 mesh / cm) attached to the bottom of the ring. Cockroach Research Containers, each with ten cockroaches, were placed in a water spray tower and were flown for more than 46 cm at a distance of 0.5 seconds. The standard test uses 1.5 g of insecticide. As mentioned below, we tested other quantities as well.

Immediately exposed to direct current, the cockroaches are transferred to a glass container for further observation. A cockroach is considered to be blocked if it rolls over on its back, whether moving its legs or mustache. Usually, if the cockroach capsizes on its back, it will not recover anymore.

% Of sputum cases depending on time (s)

<td>An example</td><td></td><td>15s</td><td>30 sec</td><td>45 sec</td><td>60 sec</td><td>75 sec</td><td>90 sec</td><td>105 sec</td><td>120 sec</td>

<td>C</td><td> 2,04</td><td> 68</td><td> 63</td><td> 66</td><td> 72</td><td> 79</td><td> 83</td><td> 89</td><td> 92</td>

<td>A</td><td> 1,46</td><td> 65</td><td> 82</td><td> 89</td><td> 95</td><td> 99</td><td> 100</td><td> 100</td><td> 100</td>

<td>Control</td><td>N / A</td><td colspan="7">Not done</td><td> 0</td>

Similar studies have been performed on other formulations. It is understood that the foregoing description relates only to a few preferred embodiments of the invention. Other forms of the invention are possible. For example, in our microemulsions we used other hydrocarbons such as dlimonene.

Industrial applicability

The invention of Ois provides environmentally safe insecticides. They are especially suitable for kitchen or indoor plants.