US2768111A - Emulsifiable insecticidal concentrates - Google Patents

Description

EMULSIFIABLE INSECTICIDAL CONCENTRATES Harry S. Butler and Clarence C. Harvey, IL, Baton Rouge, La., assignors to Ethyl Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application October 30, 1952 Serial No. 317,818

Claims. (Cl. 1617-43) This invention relates to insecticidal formulations and more particularly to emulsifiable concentrates of chlorinated insecticides.

In recent years, a number of powerful chlorinated insecticides have been developed, such as lindane and chlordane. In use, these insecticides are normally mixed with an inert carrier to facilitate application and use thereof. One preferred preparation of these insecticides is in the form of an emulsifiable concentrate which, prior to use thereof, can be diluted with water to produce a liquid adapted to be readily and easily sprayed, brushed, or otherwise employed to combat insects and pests.

The emulsifiable concentrates heretofore prepared have been excessively corrosive and have thus required special containers for storage and shipment, such as glass vessels or lined drums. These concentrates have generally been prepared with xylene or other non-polar solvent. Chlorinated insecticidal materials have limited solubility in such solvents at low temperatures and thus require blending with more powerful solvents to prevent low temperature precipitation of the insecticide, which, when precipitated, is relatively diificult to redissolve.

Various polar solvents have been found suitable as additives to the emulsifiable concentrates to improve the low temperature solubility of'the insecticide. They include ketones, ethers, and esters. However, the addition of the latter compounds to emulsifiable concentrates considerably aggravates the problem of corrosion and necessitates the use of corrosion-resistant containers for shipment and storage.

It is accordingly an object of this invention to provide an improved emulsifiable insecticidal concentrate. A further object is to provide'a concentrate of the above type having improved corrosion characteristics, while at the same time, having good low temperature solubility characteristics. Another object of this invention is to provide an emulsifiable concentrate of the above type which can be stored and shipped in conventional thinwalled metal containers wherein the corrosion rate should not materially exceed 0.001 in./year. Other objects and advantages of this invention will be apparent from the following description.

It has now been found that emulsifiable concentrates of lchlorinated insecticides can be prepared which are highly stable at low temperatures and which are essentially non-corrosive, such that they can be stored and packaged in metal containers if the insecticide is dissolved in a solvent blend consisting of a non-polar and polar solvent, the non-polar:polar solvent ratio being controlled within relatively close limits, and if, at the same time, the water concentration in the emulsifiable concentrate is maintained at a low level.

The weight ratio of non-po1ar:polar solvent should be maintained within the range of 8:1 and 1:2 and preferably the non-polar solvent should be between 55. and 65 percent by weight of the total solvent. The water concentrate, using the above solvent ratios, must be maintained below a ou Per en by g t, based o t e ice total weight of the emulsifiable concentrate, and preferably should be maintained below 0.10 weight percent. in general, the lower the concentration of water below 0.2 weight percent, the less corrosive is the concentrate for any given solvent ratio. Accordingly, it is frequently desired to maintain the water concentration below 0.05

1" tion.

weight percent of the total concentrate. Commercial grades of most common insecticidal solvents contain substantially greater concentrations of water than is tolerable in insecticidal formulations of the present inven- As noted above, however, the control of water concentration alone in formulations will not prevent corrosion, if the solvent ratio is not maintained within the above critical range.

In general, the concentration of the insecticide can range from about 1 percent to about 50 percent. Lower concentrations of insecticides are not normally desired clue to the relatively high cost of solvent. The upper concentration of the insecticide is merely controlled by the solubility characteristics of the solvent system, and the temperature conditions to which the formulation Wlll be subjected. Preferably, the insecticidal concentration is between 10 percent and 30 percent by weight of the total emulsifiable concentrate.

The total weight of the solvent blend, i. e. polar and non-polar solvents, should generally be between 6090 percent by weight of the total concentrate.

The non-polar solvents which are useful with the present invention are aromatic hydrocarbons such as benzene, xylene, toluene, mesitylene, kerosene, naphthalene, methylated naphthalenes, aromatic petroleum derivatives, and chlorinated solvents such as ethylene dichloride, mon-ochlorobenzene, carbon tetrachloride, and chloroform.

The polar solvents especially useful in the present invention are ketones, ethers, esters, alcohols and aldehydes. Typical examples of others are acetal, ethyl ether, butyl ethyl ether, benzoyl butyl ether, dioxane, benzoyl methyl ether, propyl ortho tolyl ether and Z-naphthapropyl ether. Typical examples of esters suitable as a polar solvent in the present invention are butyl acetate, ethyl acetate, and methyl propionate. Typical examples of ketones are acetone, cyclohexanone, isophorone, methyl ethyl ketone and methyl isobutyl ketone. Suitable alcohols are methanol, ethanol, normal propanol and isopropanol. Aldehydes which are suitable for this invention are butyraldehyde, benzaldehyde and ortho tolualdehyde.

The emulsifying agents useful with this invention can be selected from a wide variety of compounds. In general, any non-ionic or anionic emulsifier is suitable. However, preferably a blend of non-ionic and anionic emulsifiers is employed since such a blend assures emulsion stability in both hard and soft water. The concentration of the emulsifier is generally between 2-10 percent by weight of the concentrate, and is preferably about 5 percent thereof.

The emulsifiable concentrates of the present invention, as noted above, are mixed and emulsified with water prior to use. In general, the waterzconcentrate weight ratio can be between about 20:1 and 100:1, although greater or lesser concentrations are desired in some instances.

The following examples demonstrate the benefits of emulsifiable concentrates which have exceptionally good low temperature stability and low corrosion characteristics. In these examples, all quantities are given in percent by weight.

Example I An emulsifiable insecticidal concentrate was prepared containing 20 percent lindane dissolved in 45 percent Solvesso 150 and 30 percent isophorone. The concentrate also contained 5 percent Toximul as an emulsifier. Solvesso 150 is a commercial solvent mixture of polyalkyl benzenes containing approximately 52 percent tetramethyl benzene and 25 percent dialkyl benzenes, the remaining quantities of the solvent consisting of trialkyl benzenes and naphthalene. Toximul is a commercially avail-able emulsifying agent consisting of a blend of nonionic and anionic emulsifiers. The water concentration in this concentrate was 0.08 percent.

Corrosion tests were made with the above concentrate on iron and was found to have a corrosion rate of less than 0.00001 iii/year. The tests were conducted using sealed glass vials containing samples of the concentrate and weighed test pieces of iron. The vials were stored at 50 C. for about a three-weeks period, after which time the corrosion of the iron pieces was measured by weight loss.

The temperature of precipitation of this concentrate is below about F.

Example II Example I was repeated except that the water concentration in the emulsifiable concentrate was merely reduced to 0.58 percent of the total solution. Similar corrosion tests were conducted and the corrosion rate was found to have increased to an untenably high value of 0.018 in./year. It will thus be seen that although the water concentration in Example II was only about 7 times that of Example I, the corrosion rate increased in excess of 1800 times, even though the actual water concentration was only a fraction of 1 percent in both examples.

Example III Example I was repeated except that the water concentration was reduced to 0.14 percent and Antarox B-201 (a commercial grade of alkyl polyoxethylene glycol ester) was employed as the emulsifier. Corrosion tests conducted as in Example I showed the exceedingly low corrosion rate of 0.00003 in./year.

Example IV Example III was repeated except that the water concentration was only reduced to 0.47 percent. Corrosion tests with this concentrate gave a corrosion rate of 0.015 in./year. In comparing Examples III and IV it will be seen that an increase of approximately 3-fold in the water concentration resulted in a 500-fold corrosion rate increase.

Example V An emulsifiable concentrate was prepared employing 20 percent lindane, 37.5 percent xylene, 37.5 percent isophorone and 5 percent Antarox B-201. The water concentration in this concentrate was reduced to 0.10 percent. Corrosion tests similar to those of Example I gave a corrosion rate with this concentrate of only 0.00003 in./year.

Example VI Example V was repeated except that only'19 percent xylene was employed with 56 percent isophorone. The water concentration was again reduced to a very low value (0.008 percent). Corrosion tests with this concentrate gave the excessively high corrosion rate of 0.034 in./year. It will be seen from this example that even though the water concentration is carefully controlled, it is also necessary to control the non-polarzpolar solvent ratio to attain a non-corrosive system.

Example VII An emulsifiable concentrate containing 20 percent lindane, 45 percent mixed methylated naphthalenes, 30 percent cyclohexanone, and 5 percent sulfonated. oil containing polyoxethylene sorbital esters (Atlas (1-2081) Was tested for corrosion similar to that of Example I. The water concentration of the composition was 0.12 percent. The corrosion rate with this composition was found to be 0.0004 in./year.

Examples VIII Example VII was repeated except that the water concentration was only reduced to 0.60 percent. In this example, the corrosion rate was 0.012 in./year as compared with only 0.0004 of Example VII.

Example IX An emulsifiable concentrate was prepared containing 20 percent lindane, 56 percent methylated naphthalenes (Velsicol AR50), 19 percent isopropyl alcohol, and 5 percent Antarox B201. The water concentration was reduced to 0.02 percent. This concentrate gave a corrosion rate of only 0.0001 in./year.

Example X Example IX was repeated except that the nonpolarzpolar solvent ratio was substantially reduced. The concentrate consisted of 20 percent lindane, 19 percent mixed methylated naphthalenes, 56 percent isopropyl alcohol, and 5 percent Antarox B201. The water concentration was also reduced to 0.02 percent. However, with such a high concentration of polar solvent, the corrosion rate with this concentrate increased to 0.053 in./year.

Example XI An emulsifiable concentrate comprising 20 percent lindane, 45 percent ethylene dichloride, 30 percent butyl acetate, and 5 percent emulsifying agent, the concentrate having a water concentration of 0.1 percent.

Example XII An emulsifiable concentrate comprising 10 percent lindane, 50 percent benzene, 35 percent butyraldehyde, and 5 percent emulsifying agent, the water concentration of the concentrate being 0.05 percent.

Example XIII An emulsifiable concentrate containing 20 percent chlordane, 45 percent Solvesso 150, 30 percent isophorone and 5 percent Toximul, the water concentration in the concentrate being 0.08 percent.

Example XIV An emulsifiable concentrate consisting of 20 percent chlordane, 35.5 percent xylene, 35.5 percent isophorone, and 5 percent Antarox B-20l, the water concentration being 0.1 percent.

As is believed apparent from the foregoing, the present invention discloses an emulsifiable insecticidal concentrate which is both relatively non-corrosive and highly stable against insecticide precipitation at low temperatures. By maintenance of the water concentration in the insecticide at a level below about 0.2 percent of the formulation, and maintaining the non-polar:polar solvent ratio Within definite limits, an insecticidal formulation can be prepared, stored and shipped in thin-walled metal receptacles or containers, without undue corrosion.

We claim:

1. An emulsifiable insecticidal concentrate, comprising a chlorinated insecticide, a non-polar solvent for said insecticide, and a polar solvent for said insecticide, the weight ratio of non-polarzpolar solvent being between 8:1 and 1:2, said concentrate having water present in a concentration not exceeding 0.2 percent by weight of the concentrate.

2. An emulsifiable insecticidal concentrate in accordance with claim 1 wherein the non-polar solvent comprises 55-65 percent by weight of the total solvent.

3. An emulsifiable insecticidal concentrate, comprising a chlorinated insecticide, a non-polar solvent for said insecticide, and a polar solvent for said insecticide, the

aveslih 5 weight ratio of non-polarzpolar solvent being between 8:1 and 1:2, said concentrate having Water present in a concentration not exceeding 0.1 percent by weight of the concentrate.

4. An emulsifiable insecticidal concentrate, comprising between 1-50 percent by Weight of a chlorinated insecticide, a non-polar solvent for said chlorinated insecticide, a polar solvent for said chlorinated insecticide, the weight ratio of the non-polarzpolar solvent being between 8:] and 1:2, between 2-10 percent by Weight of an emulsifying agent, and Water in a concentration below about 0.2 percent of said concentrate.

5. An emulsifiable insecticidal concentrate, comprising between 10-30 percent by Weight of a chlorinated insecticide, between 60-90 percent by weight of a solvent 6 blend including a non-polar solvent for said chlorinated insecticide, and a polar solvent for said chlorinated insecticide, the weight of said non-polar solvent being between 55-65 percent of the total Weight of the solvent blend, about 5 percent or" an emulsifying agent, and Water in a concentration below about 0.1 percent by weight of said concentrate.

References Cited in the file of this patent UNITED STATES PATENTS 2,140,519 Elston Dec. 20, 1938 2,165,486 Jewel July 11, 1939 2,497,101 Starr Feb. 14, 1950 2,524,590 Boe Oct. 3, 1950

Claims (1)

1. AN EMULSIFIABLE INSECTICIDAL CONCENTRATE, COMPRISING A CHLORINATED INSECTICIDE, A NON-POLAR SOLVENT FOR SAID INSECTICIDE, AND A POLAR SOLVENT FOR SAID INSECTICIDE, THE WEIGHT RATION OF NON-POLAR:POLAR SOLVENT BEING BETWEEN 8:1 AND 1:2, SAID CONCENTRATE HAVING WATER PRESENT IN A CONCENTRATION NOT EXCEEDING 0.2 PERCENT BY WEIGHT OF THE CONCENTRATE.