WO1995028833A1

WO1995028833A1 - Perimeter foaming

Info

Publication number: WO1995028833A1
Application number: PCT/US1995/004867
Authority: WO
Inventors: Barbara H. Tiernan
Original assignee: Foam Innovations, Inc.
Priority date: 1994-04-20
Filing date: 1995-04-19
Publication date: 1995-11-02
Also published as: AU2391295A

Abstract

Pest infestation along a building perimeter is controlled without creating airborne liquid droplets which contain pesticide. This is accomplished by generating a wet foam comprising gas filled bubbles through nozzle (101). The foam is formed from a liquid which includes a surfactant composition and a pesticide with the liquid being entrained by the bubbles. The foam to liquid volume ratio of 2:1 to 8:1, a flowability of no more than 13 seconds and dissipates in no more than about 20 minutes. The foam is deposited onto the building perimeter (P) (including the surrounding ground surface) so as to provide a desired degree of pest control. Uniform coverage and filling of cracks and crevices results.

Description

PERIMETER FOAMING

Description

Technical Field

The present invention is concerned with a method of controlling pest infestation along a building perimeter in a manner which does not create airborne liquid pesticide containing droplets and at the same time increases pesticidal coverage by spreading to hard to reach cracks and crevices and around small barriers.

Background Of The Invention

The cor -entional method for controlling pest infestation along the perimeter of a building is to spray around the perimeter with an airborne liquid which contains a pesticide. As a result, pesticide droplets can be spread about the area in places where they are not desirable and can drift and be inhaled by people and animals, particularly if the deposition takes place on a windy day; This problem is aggravated when the pesticide spray is also deposited, as is common, along the borders of windows and doors or further up the sides of buildings, for example, in the neighborhood of the eaves. While the appliers of the pesticide can be at least partially protected via use of masks and/or protective clothing, the drift of the droplets can be considerable whereby other persons in the general vicinity, including persons on adjacent properties and beyond who are not aware of the spraying and will therefore be completely unprotected, may be contacted by the droplets. The potential exposure and health hazards are obvious. The airborne liquid droplet spraying method also suffers from the disadvantage that one cannot always be sure that each portion of the perimeter has been properly covered. This is because the liquid is generally transparent and can be rather quickly adsorbed. Thus, the user is not sure via mere observation that every portion of the perimeter has been properly coated with the airborne liquid pesticide droplets. Another problem with the application of sprayed pesticide containing liquid droplets, is that, even if properly deposited, they will not necessarily flow well into cracks and crevices. This follows because the liquid will be rapidly soaked up before it has a chance to travel whereby it will not reach distant and/or shielded areas.

A single solution to all of the above problems would be most welcome.

Disclosure Of Invention The present invention is directed to overcoming one or more of the problems as set forth above.

In accordance with an embodiment of the present invention a method is set forth of controlling pest infestation along a perimeter of a building without creating airborne liquid pesticide containing droplets. In accordance with the method a wet foam is generated which comprises a plurality of lamellae defined bubbles having gas filled interiors. The bubbles define interstitial spaces between them where the lamellae are not in contact. The interstitial spaces are generally filled with a liquid and the lamellae include the liquid from which they are formed. The liquid includes a surfactant composition and a pesticide. The wet foam formed has a foam to liquid volume ratio of between 2:1 and 8:1. The wet foam is selected so as to dissipate in not more than about 20 minutes and has a flowability of no more than about 13 seconds. A sufficient amount of the wet foam or "froth" is deposited onto the perimeter so that a sufficient quantity of the liquid will be deposited so as to provide a desired degree of pest control. A method as set forth above has a number of advantages over the prior art. No liquid droplets are formed whereby hazardous exposure is greatly reduced. The foam is merely flowed out along and in contact with the perimeter of the building where it deposits and is quite visible so that one can immediately observe whether proper coverage of the perimeter has been attained. The expansion ratio can be such that the foam is of a frothy/creaming nature. The possibility of portions of the foam itself being blown away from the application site and drifting thereby providing a hazard is prevented by using the specified wet foam rather than a drier foam which might be blown about on a windy day. The wet foam nature of the composition is such that the wet foam can much more readily flow into cracks and crevices than can the prior art airborne pesticide containing liquid formulations which can be adsorbed so readily that they do not reach such cracks and crevices. The flow into cracks and crevices is augmented by reduction of surface tension due to foaming agent incorporation. Thus, not only can one better observe in a gross manner that every bit of the perimeter has been covered, but one can also be assured that the liquid carried by the foam has been well deposited into cracks and crevices and around small obstacles along the perimeter. The effectiveness of the pesticidal barrier is thus increased through the use of foam as the pesticide delivery medium. Brief Description Of The Drawings

The invention will be better understood by reference to the figures of the drawings wherein like parts denote like parts throughout and wherein: Fig. l is a partly diagrammatic view in elevation of a foam generation system useful in the practice of the invention; and

Fig. 2 is a partially cut away view of a form of a foam applicator nozzle useful in the practice of the invention.

Best Mode For Carrying Out Invention

The present invention is concerned with the application of a pesticidal foam along the perimeter of a building. The term "perimeter" as used herein includes not only the lower few inches or feet of the foundation of the building where it contacts the soil but also a width of soil which extends outwardly from the building anywhere from a few inches to several feet. A typical label for a pesticide useful for perimeter treatment (Dursban^® manufactured and sold by DowElanco) recommends treating a width of soil extending 6 to 10 feet outwardly from the building and the foundation to a height of 2 to 3 feet. The method can also be used in outside pet bedding areas where fleas reside. Thus, a quite large area may be treated.

A useful foam in accordance with the invention can be generated by means known to the art, generally by the mixing of air with the liquid, the pesticide and a surfactant composition. The mixing should generally be vigorous enough so that the desired plurality of bubbles are produced and that the resulting foam has the required foam to liquid volume ratio of between 2:1 and 8:1. Creamy foams with a foam to liquid volume ratio between 2:1 and 6:1 and generally 2:1 and 4:1 can be particularly suitable. Expansion ratios of about 4:l and below create a "creaming foam". An apparatus capable of generating such foams is set forth in copending application Serial No. 08/063,361 which is incorporated herein in its entirety by reference.

The present invention is to mix the pesticide with water, with surfactant (or "foaming agent") and with air to provide a very specific foam. The foam that is to be applied is a particularly wet foam that contains not only the pesticide, the foaming agent, and the water, but also sufficient air to make it an effective foam. If the foam were dryer than that required by the stated foam volume to liquid volume ratio, pieces of the foam could be picked up on particularly windy days and could drift, somewhat like liquid droplets, thereby potentially constituting a health hazard. The foam can be drier or wetter (within the range of the above set forth foam volume to liquid volume ratio) depending on the location to which it is to be applied. Such a foam is, of course, temporary and does not solidify but instead dissipates over a period of time as the liquid settles out from the interstitial spaces between the bubbles and the lamellae of the air filled bubbles burst.

The term pesticide as used herein includes toxicants, repellents, attractants, chemosterilants, desiccants, disinfectants, growth regulators and phenomes which can be foamed in the manner of the invention. If the pests being controlled are ants, spiders or silverfish the pesticide will generally be a toxicant or a repellant. Mixtures of pesticides may also be applied in accordance with the invention. Thus, for example, a volatile high toxicity pesticide which dissipates quickly might be used along with a residual toxicant and/or repellant.

The pesticide is preferably chosen with reference to the particular pest which is to be attacked. Without limitation, the pests may typically be ants, spiders, mites, cockroaches, fleas, house nesting flies, silverfish, hornets, earwigs, wasps, beetles, carpenter ants, carpenter bees, millipedes, mosquitos, scorpions, ticks, yellowjackets, bees, sowbugs, and/or crickets. Pesticides, especially insecticides which have been found to be suitable for application in a foam to confined spaces, include carbamates, pyrethroids, organophosphates, chlorinated hydrocarbons, and various growth regulators. For example, carbamates can be combined with foaming surfactants to make foams that will be pesticidal to Lepidoptera (moths, skippers, butterflies, etc.); Orthopetra (roaches, locusts, grasshoppers, crickets, mantises, etc.); Diptera (flies, mosquitoes, gnats, midges, etc.); Coleoptera (beetles); Hymenoptera (ants, bees, wasps, yellow jackets, hornets, etc.); Thysanura

(silverfish, firebrats, etc.); Anoplura (lice, etc.);

Thysanoptera (thrips, etc.); Dermaptera (earwigs, etc.); Isopoda (sowbugs, pull bugs, etc.); Diplopoda (millipedes, etc.); Siphonoptera (fleas); and Chilopoda (centipedes, etc.).

Pyrethrins can also be used to control Lepidoptera, Hemiptera, Orthoptera, Diptera, Coleoptera, Hymenoptera, Thysanura, Araneida, Acarina, Siphonaptera, and Isopoda.

Similarly, pyrethroids can be used to control

Lepidoptera; Hemiptera; Orthoptera; Diptera; Homoptera

(leaf hoppers, tree hoppers, cicadas, spittle bugs, etc.); Coleoptera; Hymenoptera; Araneida; Acarina; Siphonaptera (fleas, etc.); Thysanoptera; Dermaptera; Isopoda; and Chilopoda.

Organophosphates may be used to control Lepidoptera, Orthoptera, Diptera, Coleoptera, Hymenoptera, Thysanura, Araneida, Acarina, Siphonaptera, and Isopoda.

Growth regulators, such as Gencor, may be used to control orthoptera and other pests.

It is generally preferred that the pesticide have a residual effect. Such pesticides are generally referred to in the trade as residually effective pesticides. The term residual, when applied to toxic pesticides is defined in "Pesticides Theory and Application", George W. Ware, W.H. Freeman and Company, New York, 1983 as "Having a continued lethal effect over a period of time." As used herein the term is somewhat more broadly used to include pesticides having a continued "residual" repellant effect.

It should be noted that while knock down has some desirability it is of relatively little importance when the foam is used to deliver pesticide which is used to protect structural parts and buildings from pests such as ants. In such instances and in many other instances what is necessary is a residual effect. The pesticide need not be effective as a toxicant. A repellant property can be equally or more effective in attaining the desired result, so long as the pesticidal activity is residual.

All these classes of insecticides with the added foaming agents, have been tested for foaming to make a foam that is suitable for application along building peripheries. Commercial formulations of pesticides are sometimes difficult to get to achieve an effective foam (generally defined as an air to liquid ratio, more properly a foam volume to contained liquid volume ratio, of between 2:1 and 8:1). However, there are a great multitude of foaming agents available on the market and this difficulty can be readily overcome by simply formulating a composition and then testing it as set forth herein to confirm that it satisfies the requirements for a foam useful in the practice of the invention. If the first formulation made and tested does not work as desired it is simple to test another (and another if needed) until an acceptable formulation results. The foaming agent may be of anionic, cationic, amphoteric or non-ionic type and may constitute a mixture of one or more of these types of foaming agents. There are hundreds of commercially available foaming agents which can be selected for use in forming the foam used in the practice of the invention. The foaming agent will, of course, be chosen so as to not interfere with the operation of the pesticide and so as to not react with the pesticide in any manner which would deleteriously effect the pesticides ability to provide the desired pesticidal action. It will also be chosen taking into account the chemical nature and physical, including surfactant, properties of the particular pesticide being used.

The liquid substance from which the pesticide foam is made may comprise a pesticide, a foaming agent, and water. The liquid pesticide and water may be combined with the liquid foaming agent in a suitable receptacle or tank (identified as element 10 in Figure 1) , and the combined solution may be, via line 11, pumped by pump 12 driven by engine 13, as moderated by pressure regulator 16, into line 20 and past valve 21 to T-connector 25 and, in T-connector 25, into a given quantity of a compressed gas, generally air compressed by compressor 27 and flowing past check valve 28. The amount of compressed air and foaming agent used will vary with the pesticide and the application but will be selected so as to provide a foam of the required expansion ratio. The expansion ratio can be readily measured by simply collecting a measured volume of the foam, waiting until it liquifies, and then noting the volume of the resulting liquid. The foam proceeds via line 30 and spreads outwardly as it exits foam applicator 35 with flow being controlled by valve 36. In accordance with the invention the amount of compressed air will be such as to provide a very wet foam, which, for the purpose of this disclosure is defined as an effective foam having a foam volume to liquid volume expansion ratio of between 2 to 1 and 8 to 1, more preferably of between 2 to 1 and 6 to 1 and generally of between 2 to 1 and 4 to 1. Such foams are quite flowable, having flowability characteristics which allow them to flow into cracks, crevices and cavities and the like and are sufficiently concentrated in pesticide so as to provide reasonably high levels of a residual pesticide upon the surfaces which they contact utilizing pesticidal liquids which do not have unacceptably high levels of the pesticide. Also, such foams are heavy enough, due to their significant liquid content, so as to not readily become airborne and spread to create a hazardous condition.

In order to prepare a foam that is suitable for use in the practice of the invention it is necessary that the foam have a proper flowability so as to allow it to readily flow into cracks, crevices and cavities. Flowability is a measure of the rate at which a foam flows, or foam fluidity and is definable by the following test. The equipment used for determining foam fluidity for purposes of this invention consists of a rigid cylindrical tank measuring 29 cm in diameter and 37 cm in length. The top surface and cylindrical wall of the tank are closed, except for a small orifice in each. The base of the tank is closed. Specifically, the top surface of the tank has a 6 cm (diameter) orifice within about 1 cm from the tank perimeter. The lower portion of the cylindrical wall has a 5 cm (diameter) orifice within about 1 cm from the base of the tank, and diametrically opposite the orifice in the top surface. The tank is oriented such that its vertical axis is at a 45° angle with the horizontal and the 5 cm orifice projects downwardly.

In use, the 5 cm orifice is sealed and the tank is filled through the 6 cm orifice with the foam to be tested. Upon complete filling, the seal is removed immediately from the 5 cm orifice. The time required to drain at least about 80% of the foam from the tank is a measure of the flowability of the foam. (Since burrs or other rough features in the 5 cm orifice can increase the friction experienced by the draining foam and therefore adversely impact the time for draining, the 5 cm orifice should be smooth- walled.)

Acceptable flowability results when the time is less than about 13 seconds. Foams with a foam-to- liquid ratio above 8:1 have a rigidity which causes them to lack adequate fluidity for perimeter foaming, i.e., require more than about 13 seconds to drain from the tank.

Also, while foams with expansion ratios between 2 to 1 and 8 to l have reasonable lasting properties, by which is meant they last long enough to expand into cracks and crevices and deposit their pesticide on the surfaces that they contact, they generally dissipate within a reasonable time, as well, for example in less than 20 minutes, suitably from l to 20 minutes, preferably in 1 to 10 minutes, whereby if more pesticide is necessary than can be deposited in a single foaming application using pesticidal solution containing an allowable concentration of pesticide, such can be accomplished by retreating the perimeter by an additional deposition of foam. Quick dissipation also serves to preclude pets and small children from ingesting the pesticide.

In accordance with the embodiment of the present invention illustrated in Figure 2, the depositing of the foam is through flowinc the foam through a nozzle or deposition head 101 of the foam applicator 35, the deposition head 101 defining one or more openings 103 (usually one opening) arranged so that the foam flows out of the opening(s) 103 and spreads along a deposition line, L, the length of which will be determined by the precise deposition head 101 used to deliver the foam and the distance from the perimeter at which the nozzle is positioned during deposition. The deposition head 101 is moved along the perimeter, P, of the building with the deposition line, L, aligned generally perpendicular to the direction of motion and in such an orientation that the wet foam is deposited in a band of a desired width along the perimeter, P. The deposition head can be moved, as needed, by the operator so as to provide building and/or ground coverage in accordance with the pesticide manufacturers directions. The deposited wet foam is then in the nature of a relatively wide band running about the perimeter. The foam is visible so that the applier can see that no spots have been missed. The foam can also be applied about windows and other portions of the structure.

In an alternate construction, the solution, mixed with air, can be pushed through a mixing chamber which "works" the combination into a foam, as by moving it past various surfaces, thereby refining it into small dense bubbles and increasing the uniformity and durability of the bubbles or foam particles. Such a construction is set forth in previously incorporated copending application Serial No. 08/063,361.

In yet another construction the solution can be pumped to a nozzle without adding compressed air before the nozzle. A venturi nozzle can then be utilized to draw in and mix in air and the foam will form as the solution flows out of the nozzle.

Industrial Applicability

The present invention provides a method for controlling pest infestation along the perimeter of a building without creating airborne pesticide containing droplets which can drift and create an environmental hazard. The foam which is deposited is readily visible so that the applier can be certain that areas have not been missed along the perimeter. Also, the foam composition is such that it will better fill cracks and crevices than will prior art airborne liquid perimeter sprayings.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.

Claims

ClaimsThat which is claimed is:

1. A method of controlling pest infestation along a perimeter of a building without creating airborne liquid pesticide containing droplets, comprising:

generating a temporary non-solidifying wet foam comprising a plurality of lamellae defined bubbles having interiors filled with a gas, the bubbles defining interstitial spaces between them where the lamellae are not in contact, the interstitial spaces and the lamellae including a liquid therein, the liquid including a surfactant composition and a pesticide, the wet foam having a foam to liquid volume expansion ratio of between 2:1 and 8:1 and a flowability of no more than about 13 seconds, the wet foam dissipating in no more than about 20 minutes;

depositing the wet foam in a band along the perimeter, a sufficient amount of the wet foam being deposited so that sufficient of the liquid will be deposited so as to provided a desired degree of pest control.

2. A method as set forth in claim 1, wherein the foam dissipates in from 3 to 20 minutes.

3. A method as set forth in claim 2, wherein the expansion ratio falls between 2:1 and 6:1.

4. A method as set forth in claim 3, wherein the pest infestation comprises an ant, spider, mite, cockroach, flea, flies, silverfish, hornet, earwig, wasp, beetle, carpenter ant, carpenter bee, millipede, mosquito, scorpion, tick, yellowjacket, bee, sowbug or cricket infestation.

5. A method as set forth in claim 3, wherein the expansion ratio falls between 2:1 and 4:1.

6. A method as set forth in claim 5, wherein the pest infestation comprises an ant, spider, mite, cockroach, flea, flies, silverfish, hornet, earwig, wasp, beetle, carpenter ant, carpenter bee, millipede, mosquito, scorpion, tick, yellowjacket, bee, sowbug or cricket infestation.