Note: Descriptions are shown in the official language in which they were submitted.
211~02
The present invention relates to a senko
containing silicon carbide and a composition used as a
material for the senko.
The senko refers to a substance for
volatilizing an active ingredient in the air by
incomplete combustion. Usually, specific examples of
the senko include an insecticidal senko called a
mosquito coil, and a perfume-emitting senko called an
incense stick which includes for example a senko for
Buddhist mass called a joss stick.
Hitherto, various kinds of senko containing an
insecticidal active ingredient or a perfume-emitting
active ingredient have been used. Generally, a
substantial part of these active ingredients contained
in the senko is decomposed by combustion heat and the
effectively volatilizing part is limited.
The present invention was made to improve the
volatilization rate of the active ingredient in the
senko, and it provides a senko containing silicon
carbide and a composition used as a material for the
senko.
The senko of the present invention contains
silicon carbide usually in the form of a powder, and
the content of silicon carbide is l to 30 wt.%,
preferably 1 to 20 wt.% of the total weight of the
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senko The senko of the present invention comprises
other materials commonly used for senko such as organic
fillers, binders and additionally pigments and
fungistats as necessary
The active ingredient used in the insecticidal
senko for killing flies, mosquitoes, etc., which is
generally called a mosquito coil, includes pyrethroid
compounds s~ch as pyrethrin, allethrin, prallethrin,
benfluthrin (transfluthrin), resmethrin, empenthrin,
their active stereoisomers and mixtures of these
stereoisomers. The active ingredient used in the
perfume-emitting senko includes natural perfumes,
synthetic perfumes and the like. The content of these
active ingredients is generally 0.01 to 1.0 part by
weight of the total weight of the senko.
These active ingredients are mixed with the
materials for senko as they are or after formulated
into emulsifiable concentrates, oil sprays, micro-
encapsulated formulations, various inclusion complex
formulations, etc. and if necessary diluted with a
solvent or vegetable oil.
The solvent includes those having a boiling
point of 100C or more and a vapor pressure of 1 mmHg
or more at 20C, which are selec-~ed from the group
consisting of liquid paraffin, aliphatic hydrocarbons
having 10 or more carbon atoms, aromatic hydrocarbons,
halogenated hydrocarbons having 3 or more carbon atoms,
alcohols and esters having 3 or more carbon atoms.
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The vegetable oil includes avocado oil,
almond oil, persic oil, coconut oil, palm oil, olive
oil, castor oil, peanut oil, rape seed oil, rice bran
oil, sesame oil, cotton seed oil, corn oil, soybean
oil, tung oil, linseed oil, perilla oil, torreya seed
oil, safflower oil, bran oil, kapok oil, spicebush oil,
sasanqua oil, tea seed oil, and camellia oil.
A preferred organic filler used as a material
for senko includes those emitting little smoke or
offensive odor by combustion at relatively low temper-
atures. It includes for example dry powders of woody
parts of juniper, sandal wood, camphor tree, Japanese
cedar, willow, Kalopanax pictus, Magnolia hypoleuca,
lime tree, orange peel, fir, yellow poplar, Japanese
Judas-tree, acacia, poplar, Tilia Miqueliana, Toisusu
Urbaniana, Pterocarya rhoifolia, Thuja Standishii,
paulownia, Fraxinus Spaethiana, lauan, white birch,
citrus fruits, woods for shiitake fungus, etc.; dry
powders of plants such as Compositae, Umbelliferae,
Gramineae, Meliaceae, Thymelaeaceae, Myrtaceae,
Moraceae, Oleaceae, Labiatae, Rubiaceae, Caprifoliaceae
and rice chaff; and dry powders of plant extract such as
Pyrethrum marc obtained by extraction of Pyrethrum.
These organic fillers may be used in mixture.
The binder used as a material for senko
includes natural polymers such as starch, mannan,
powdered algae extracts, Hibiscus Manihot powder, gum
tragacanth, gum arabic, guar gum, powdered gambier
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extracts, powdered Machilus thunbergii bark-extracts
(called a tabu-powder) and casein; and synthetic
polymers such as polyvinyl alcohol, polyacrylamide,
sodium polyacrylate, polyethylene oxide, polyvinyl
pyrrolidone, methyl cellulose, ethyl cellulose,
hydroxyethyl cellulose, hydroxypropyl cellulose, the
salt of carboxymethyl cellulose, the salt of carboxy-
methyl starch, dialdehyde starch and cationic starch.
These binders may be used in mixture.
The pigment used as a material for senko
includes organic pigments (e.g. malachite green),
inorganic pigments, dyes and the like. The fungistat
used as a material for senko includes acids such as
benzoic acid, sorbic acid and dehydroacetic acid and
their salts, p-hydroxybenzoic acid esters, salts of
propionic acid, o-phenylphenol and the like. These
materials may be used in mixture of two or more of them.
The senko of the present invention may be
produced by mixing the above materials for senko,
kneading the mixture with water, extruding and stamping
the kneaded product into optional forms with extruding
and stamping machines, and then air-drying the product
or drying it with driers.
The present invention will be illustrated
more specifically with reference to the following
examples, but it is not to be interpreted as being
limited thereto.
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Production Example -~
0.09 Part by weight of an emulsifiable
concentrate containing prallethrin (pyrethroid
insecticidal compound), [which comprises 0.088 part by
weight of prallethrin, 0.01 part by weight of Hymal BLZ
(a surface active agent produced by Matsumoto Yushi-
Seiyaku Co., Ltd.), 0.001 part by weight of Hymal 1002Z
(a surface active agent produced by Matsumoto Yushi-
Seiyaku Co., Ltd.) and 0.009 part by weight of Solvesso
150 (a solvent produced by Exxon Chemical Co.)], 10.0
parts by weight of silicon carbide powder, 40.0 parts by
weight of Pyrethrum marc, 30.0 parts by weight of tabu
powder, 0.3 part by weight of malachite green and 0.2
part by weight of sodium dehydroacetate were mixed
together, and the total weight of the mixture was made
up to 100 parts by weight with Japanese cedar powder.
A proper amount of water was added to the resulting
mixture which was then thoroughly kneaded, extrusion-
stamped and dried to obtain a mosquito coil.
Comparative Example
A mosquito coil was obtained in the same
manner as in Production Example except that 50.0 parts
by weight of Pyrethrum marc was used in place of 10.0
parts by weight of silicon carbide powder and 40.0
parts by weight of Pyrethrum marc.
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Test Example
Using the mosquito coils obtained in the
Production example and Comparative Example, the
volatilization rate of prallethrin as an active
ingredient was measured as follows.
The weighed sample is fixed to a senko-holder
and burned in a measuring instrument (a wide-mouthed
funnel). The smoke emitted by burning is caught by
causing silica gel to adsorb the smoke while sucking
the smoke by means of a suction pump. Thereafter, the
measuring instrument, silica gel, etc. are washed with
methanol, and the amount of prallethrin in the methanol
washings is determined by gas chromatography.
The results of measurement of the volatili-
zation rate are shown in Table 1.
Table 1
Sample Volatilization rate (~) ¦
Production Example 72
Comparative Example 59
The senko of the present invention canefficiently volatilize an active ingredient and may be
used in various applications.
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