Fishing – trapping – and vermin destroying – Vermin destroying – Fumigators
Reexamination Certificate
1999-12-15
2001-09-11
Jordan, Charles T. (Department: 3644)
Fishing, trapping, and vermin destroying
Vermin destroying
Fumigators
Reexamination Certificate
active
06286248
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
The present invention relates to vertically disposed, rope-like structures that are ignitable from their top to dispense desired volatile materials, including, by way of example only, insect control actives such as insect repellents.
The fact that certain combustible materials can be ignited and will then disperse an active ingredient as they continue to smolder is well known. Incense sticks and mosquito coils are examples of products made from such materials. See e.g. U.S. Pat. Nos. 4,959,925 and 5,657,574. The disclosure of these publications and of all other publications referred to herein are incorporated by reference as if fully set forth herein.
The term “fumigant” herein means a burnable material that releases a volatile ingredient as the material burns, and preferably as it slowly smolders. A “volatile material” or “volatile ingredient,” in that context, means any material that can be released by a burning fumigant including, by way of example only, fragrances, disinfectants, and insect control actives. The term “active” refers to a volatile material to be released in order to achieve the desired effect of the fumigant. For a fumigant intended to repel mosquitoes, for example, an insect repellant would be an “active.” An “insect control active” is an active that repels, kills, or desirably modifies the behavior of insects. “Insects” herein means actual insects, as well as other small animals commonly controlled in conjunction with insects, such as spiders and the like.
While conventional fumigants in the form of mosquito coils or repellent sticks are fairly inexpensive, they are often used in large quantity (e.g. thirty or so a month may be needed to control mosquitoes on an overnight basis). Further, these coils are most often used in countries having average annual income levels that are very low. In order to make such products more widely available, their cost must be reduced still further. This is particularly important in controlling the spread of malaria and certain other insect-borne diseases.
There have been attempts to reduce the cost of mosquito protection by burning widely available, very inexpensive, smoke-producing materials that are used without any insecticide. However, efforts to control mosquitoes by burning materials of this type, such as by burning cow dung, are not very effective and can have other undesirable characteristics, such as excessive odor.
Academic researchers in India have proposed the use of jute rope that has been impregnated with a mosquito repellant as a fumigant. This approach uses a relatively limp impregnated rope suspended from a hanger, which is lit on its lower end and permitted to smolder overnight. See M. Ansari et al., 31 Indian J. Malariology 57-64 (1994); M. Ansari et al., 29 Indian J. Malariology 203-210 (1992); and V. Sharma et al., 26 Indian J. Malariology 179-185 (1989).
Unfortunately, this technique produces inconsistent results as burning rates can not be precisely controlled and, especially, can be too rapid. Also, there is some fire risk if the characteristics of the rope are not carefully controlled. For example, fire can flash up the rope, contacting structures from which the rope has been hung. Metal mesh fire guards have been shown to attempt to control this risk. Further, a portion of the rope is sometimes wasted near its upper end, as contact with the suspension device snuffs the rope.
Wax candles, having conventional fiber wicks surrounded by wax, are of course also well known. They are sometimes supported in a hollow core of a corkscrew-like wire, positioned on a flat surface. Some such candles have insect repellent (such as citronella) incorporated in the wax. However, such designs require the use of relatively expensive candle wax.
Thus, there is still a need for improved fumigants, particularly those that can dispense insecticide or insect repellent at extremely low cost.
SUMMARY OF THE INVENTION
In one aspect, the invention provides a burnable fumigant. It has an elongated, preferably twisted or braided strand or otherwise formed rope or rope-like structure (preferably of at least 5 mm in diameter) which is sufficiently rigid that, when supported from its lower half, it maintains its upper half in a position sufficiently upright that the uppermost end of the rope-like structure remains at least level with or, preferably, above the remainder of the rope-like structure, even without an external support contacting its upper half. It is preferred that the upper half, when so held, droop no more than about 80 degrees from the vertical and, more preferred for easy holding and use, no more than 45 degrees. Ideally, the upper half should remain substantially vertical when so held. All such orientations will sometimes be referred to herein as being “functionally vertical.” Preferably the rope-like structure remains functionally vertically disposed even when supported over no more than its lower third, better over no more than its lower fourth, and ideally over no more than its lower eighth.
While the rope-like structure can include braided or twisted strands, it can also be made from strands formed into a rope-like structure by being compacted, felted, or similarly processed. The rope-like structure can be made of a very inexpensive material such as jute or other fibrous plant materials.
There is an active on the surface of, impregnated in, or otherwise borne by the rope-like structure. The active preferably is an insect control ingredient, a fragrance, or a combination of the two. In especially preferred forms, the active includes an insecticide or an insect repellent. Two such actives are esbiothrin (d-trans chrysanthemate of d-allethrolone) and Pynamin Forte® (d-cis-trans-chrysanthemate of dl-allethrolone), both available from AgrEvo Environmental Health, Inc. and Sumitomo, respectively.
In one embodiment, a strand or other longitudinally extending first portion of the rope-like structure has either no active or only selected actives. Another, co-extending, second portion of the rope-like structure does have one or more actives not present in the first portion and, preferably, also is colored, preferably with a dye, so that the second portion is visually distinguishable from the first portion. This provides a quality control feature to insure inclusion of a specifically treated strand in the final product, minimizes the amount of active needed for any given height and thickness of the structure, may also provide perceived value in the mind of the consumer, and can be used to visually distinguish among different actives or active concentrations in otherwise similar products. Thus, by way of example only, a product having a higher concentration of active for use in extreme conditions can be distinguished at a glance from a low active concentration product.
The rope-like structure preferably is literally a rope between 5 mm and 15 mm in diameter. With this diameter, tightly wound jute rope, held vertically from the bottom, typically can extend upwardly as much as 30 cm and remain functionally vertical. A length of rope held generally vertically from the bottom for burning from its upper end will sometimes be called a “rope candle” herein. The rope candle preferably is held up in a coil holder that supports it only from its lower half (preferably only from its lower third, more preferably from its lower fourth, or, ideally, its lower eighth). This reduces the likelihood that contact between the holder and smoldering rope will extinguish the rope prematurely.
Another form of the invention provides a method of controlling insects. One positions the above fumigant such that it is functionally and preferably essentially vertically disposed and ignites an upper end of the fumigant. Preferably, the upper end is treated with an igniter material such as sodium nitrate.
A wide variety of insect control actives are suitable for use with the present invention. Pyrethrum or py
Bryant Harry E.
Gundlach Douglas P.
Hildebrandt Donald W.
Jordan Charles T.
Lofdahl J
S. C. Johnson & Son Inc.
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