Insecticidal mat and heat-transpiration insecticidal method...

Details Insecticidal mat and heat-transpiration insecticidal method... Insecticidal mat and heat-transpiration insecticidal method...

2001-05-29

2004-03-23

Levy, Neil S. (Department: 1616)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S405000, C424S040000, C514S531000

Reexamination Certificate

active

06709666

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an insecticidal mat containing an insecticidal ingredient, and to a heat-transpiration insecticidal method in which the mat is set on a radiation plate of a portable heat-transpiration apparatus to thereby transpire the insecticidal ingredient.
2. Description of the Related Art
Hitherto, as a method of heat-transpiring an insecticidal ingredient for killing insects or the like, (1) a mosquito-repellent incense, (2) an electric mosquito-repellent mat have been used favorably, and (3) a liquid mosquito-repellent, that is, a method of heat-transpiring an insecticidal solution by soaking an absorbent wick in the insecticidal solution and heating the upper part of the wick has been popular in recent years.
Of those, the electric mosquito-repellent mat works by means of setting a fibrous mat impregnated with an insecticidal ingredient on a radiation plate of the heat-transpiration apparatus, and heating the mat with electricity to transpire the insecticidal ingredient contained therein. The temperature at the central portion of the radiation plate is generally set in the range of 140 to 180° C. The mat which is effective for 8 to 10 hours in a room of about 10 m
2
contains, for example, about 40 mg of allethrin as the insecticidal ingredient per mat. However, such an electric mosquito-repellent mat is for use in a closed room, and of course cannot be used outdoors where there is no power supply. For this reason, development of a portable mosquito-repellent utilizing a battery, or oxidation heat or burning heat of liquefied gas is progressing. For example, Japanese Patent Examined Publication No. Hei. 5-81801 discloses a portable heat-transpiration apparatus comprising a burner means which flame burns a fuel in a pipe to heat the pipe as a heating member, and a disposable and exchangeable fuel cartridge which supplies a fuel to this burner means, wherein the fuel cartridge has a fuel supply valve means which controls flow of fuel. Recently, mosquito-repellent sets utilizing this portable heat-transpiration apparatus are commercially available. However, its use time is short as about 4 hours, and improvement is demanded in the point of sustainability of the insecticidal effect, or the like.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an insecticidal mat which is applied to a portable heat-transpiration apparatus and is capable of continuously maintaining an insecticidal effect over 8 hours or longer even in an open space such as the outdoors, and a heat-transpiration insecticidal method using the same.
In order to attain the object described above, the present inventors investigated in detail the shape of a fibrous mat, the kind and composition of an insecticidal ingredient impregnated in the fibrous mat, and a combination with performance of a portable heat-transpiration apparatus, to thereby find that the insecticidal effect can continuously be maintained over 8 hours or longer even in an open system space such as the outdoors.
That is, a first aspect of the present invention relates to an insecticidal mat comprising a fibrous mat having a size of 1,000 to 2,500 mm
2
which contains 250 to 600 mg of allethrin as an insecticidal ingredient, 600 to 1,000 mg of piperonyl butoxide as a volatization controlling agent and 10 to 100 mg of at least one member selected from the group consisting of 2,5-di-t-butylhydroquinone, 3,5-di-t-butyl-4-hydroxytoluene and 3-t-butyl-4-hydroxyanisole as a volatization controlling agent per mat, wherein the mat is used by setting on a radiation plate which has an area of 1,000 to 2,500 mm
2
, has a temperature of 150 to 190° C. at its central portion, and has a temperature difference of 10° C. or less between the central portion and its edge portion.
In the present invention, the fibrous mat having a size of 1,000 to 2,500 mm
2
is used in order to increase a transpiration amount of the insecticidal ingredient per unit time, thereby exhibiting a sufficient insecticidal effect even in an open space.
As the material of the fibrous mat, that of the same quality as the conventional mosquito-repellent mats such as pulp, linter, or a mixture of them can be used. The mat having a thickness of 1.5 to 3.0 mm can be used with ease.
The insecticidal ingredient used in the present invention is allethrin of a pyrethroid compound having high safety. The allethrin has a vapor pressure at 20° C. of 5.6 mPa and is suitable as an insecticidal ingredient for a heat-transpiration apparatus used in an open space. Optical isomers based on asymmetric carbon in a chemical structure, such as each or any mixtures of pynamin forte, bioallethrin, esbiothrin and esbiol, can of course be included in the insecticidal ingredient of the present invention.
The allethrin is contained in an amount of 250 to 600 mg per mat. If the amount is less than 250 mg, the insecticidal effect cannot be exhibited over a long period of time. On the other hand, if the amount exceeds 600 mg, there is caused difficulty in the impregnation in the insecticidal mat, which is not preferable.
The insecticidal mat of the present invention contains a volatilization controlling agent in order to sustain the insecticidal effect in an open space. The volatilization controlling agent is used in a combination of 600 to 1,000 mg of piperonyl butoxide which is suitable for allethrin and 10 to 100 mg of at least one member selected from the group consisting of 2,5-di-t-butylhydroquinone (compound A), 3,5-di-t-butyl-4-hydroxytoluene (compound B) and 3-t-butyl-4-hydroxyanisole (compound C). That is, compounds other than piperonyl butoxide known as a volatilization controlling agent, such as butyl stearate or octachlorodipropyl ether, are not suitable for use in the present invention, and satisfactory volatilization controlling effect cannot be obtained by the use of piperonyl butoxide alone. The present invention is characterized in the combination of at least one member selected from the group consisting of compound A, compound B and compound C with piperonyl butoxide.
If the amount of piperonyl butoxide contained is less than 600 mg, the volatilization controlling effect becomes poor, and on the other hand, if the amount exceeds 1,000 mg, the insecticidal effect is suppressed, and also there is caused difficulty in the impregnation in an insecticidal mat, which are not preferable.
At least one member selected from the group consisting of compound A, compound B and compound C is contained in an amount of 10 to 100 mg, preferably 30 to 60 mg, per mat, thereby exhibiting the volatilization effect in combination. If the amount is less than 10 mg, the volatilization controlling effect is not obtained, and on the other hand, if the amount exceeds 100 mg, the insecticidal effect is suppressed. Further, because those compounds are crystalline, there is the problem that if the amount thereof exceeds 100 mg, it is difficult to dissolve. Of the above three kinds of compounds, 2,5-di-t-butylhydroquinone (compound A) is most preferable, and combination of this compound with piperonyl butoxide exhibits particularly excellent volatilization performance, thereby sustaining the insecticidal effect over a long period of time.
In preparing the insecticidal mat of the present invention, an undiluted solution (base solution) is used which is generally obtained by adding perfumes, dyestuffs and the like, and also solvents such as kerosene, to the above described allethrin and volatilization controlling agent. However, there is set a limit on the maximum holding liquid amount in the mat. Therefore, the amount of undiluted solution is preferably used in an amount of 1.5 g or less per mat in the case of the mat having a size of 35×50 mm and a thickness of 2.0 mm.
In the present invention, insecticidal ingredients other than allethrin, for example, furamethrin, prallethrin, empenthrin, transfluthrin, acaricides, repellents, spatial bactericides and antibacterials such as hinokitiol, linalool, citral, pinene, menthol, terpene

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