Controlled release insect pest repellent

A controlled release insect pest repellent comprising p-menthane-3,8-diol blended with an ethylene/vinyl acetate copolymer is disclosed. This controlled release insect pest repellent can show continuous controlled release of the repellent component, i.e., p-menthane-3,8-diol, for a prolonged period of time so as to effectively exterminate insect pests.

FIELD OF THE INVENTION 
This invention relates to a controlled release insect pest repellent. More 
particularly, it relates to a controlled release insect pest repellent 
which is prepared by blending p-menthane-3,8-diol having a repellent 
effect on insect pests with a specific base having an appropriately 
controlled affinity therefore so as to slowly volatilize and release the 
p-menthane-3,8-diol from the surface of the base for a prolonged period of 
time. 
BACKGROUND OF THE INVENTION 
It has been known that p-menthane-3,8-diol has a repellent effect on insect 
pests such as the mosquito, slug, millipede, night crawler and flea (see 
H. Nishimura, J. Mizutani, T. Umino & T. Kurihara, 6th Intern. Congr. 
Pesticide Chem., Abstracts 2D/E-07, Ottawa, Canada, Aug. 10-15th (1986); 
H. Nishimura, Eucalyptus as Future Biosource, and Biotechnology and 
Bioscience Thereof, Uchidarokakuho (1987); H. Nishimura, T. Nakamura & J. 
Mizutani, Phytochemistry, 23, 2777 (1984); H. Nishimura, Fragrance 
Journal, No. 75, 160 (1985); and H. Nishimura, K. Kaku, T. Nakamura, Y. 
Fukazawa & J. Mizutani, Agric. Biol. Chem., 46, 319 (1982)). The 
p-menthane-3,8-diol involves structural isomers and optical isomers, 
namely, (+)-cis-p-menthane-3,8-diol, (-)-cis-p-menthane-3,8-diol, 
(+)-trans-p-menthane-3,8-diol and (-)-trans-p-menthane-3,8-diol. Each 
substance has a melting point ranging from 57 to 60.degree. C. It is in 
the form of a solid at room temperature but has a volatility in this 
state. Thus, it can exert the repellent effect on insect pests under 
certain atmosphere. When p-menthane-3,8-diol is not blended with a base 
but used as such, however, it exhibits volatility even in the form of a 
solid at room temperature, as described above, and the volatilization rate 
thereof cannot be controlled, which brings about serious waste. 
In contrast thereto, JP-A-60-199804 (the term "JP-A" as used herein means a 
"published unexamined Japanese patent application") describes "A collar to 
which a resin impregnated with a repellent such as p-menthane-3,8-diol 
(PM) is used for pet such as dog". However, no particular resin is not 
specified therein. The addition of PM to resins, other than some limited 
ones, would be useless because of the following facts: (1) the added PM 
bleeds out onto the surface of the resin, which makes it impossible to 
control the volatilization rate thereof; or (2) the added PM is enclosed 
within the resin and can hardly volatilize. 
When p-menthane-3,8-diol is added to a base resin comprising a single 
homopolymer, it is impossible to slowly volatilize and release the 
p-menthane-3,8-diol within an effective range from the surface of the base 
resin for a prolonged period of time, namely, so-called controlled 
release. The reason is as follows. 
When a volatile substance is uniformly contained in a base material, the 
volatile substance present on the surface of the base material would 
volatilize into the atmosphere depending on its inherent vapor pressure. 
As a result, the concentration of the volatile substance on the surface of 
the base material differs from that at the core part, thus forming a 
concentration gradient. Then, the volatile substance present at the core 
part would slowly migrate into the surface layer and then volatilize into 
the atmosphere. Thus, the volatile substance within the base material 
would continuously volatilize into the atmosphere while maintaining the 
above flow. In order to slowly release a volatile substance in an 
appropriate amount for a prolonged period of time, therefore, it is 
required that the volatile substance is uniformly contained in a base 
material at a concentration allowing the formation of a continuous layer 
thereof; and that the migration rate of the volatile substance in the base 
material is controlled in such a manner that the volatile substance can 
volatilize at an appropriate volatilization rate. 
The affinity of the base material for the volatile substance closely 
relates to the concentration and migration rate of the volatile substance. 
Thus, it is difficult to slowly release the volatile substance in an 
appropriate amount unless the affinity is appropriately controlled. When 
the affinity is excessively low, the compatibility between these 
substances becomes low. Thus, the volatile substance can be added to the 
base material only in a small amount. In this case, therefore, it is 
difficult to slowly release an appropriate amount of the volatile 
substance for a long time. When the affinity is excessively high, on the 
other hand, the high compatibility between these substances makes the 
migration rate of the volatile substance in the base material extremely 
low. In this case, therefore, it is difficult to volatilize an appropriate 
amount of the volatile substance. 
When the base resin to which PM is to be added is a homopolymer, it is 
impossible to appropriately control the affinity of the base resin for PM, 
which causes the following problems. When the affinity of the homopolymer 
for PM is low, PM can be added only in a small amount. Thus, it is 
difficult to control the repellent effect of PM for a long time. When the 
affinity of the homopolymer for PM is high, on the other hand, the 
migration rate of PM becomes extremely low. Thus, it is difficult in this 
case to release PM in a satisfactory amount for achieving the aimed 
repellent effect. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a controlled release 
insect pest repellent which can slowly volatilize and release 
p-menthane-3,8-diol in an effective amount for exerting a repellent effect 
on insect pests for a prolonged period of time. 
It is another object of the present invention to provide a controlled 
release insect pest repellent having excellent molding properties. 
The present inventors have conducted extensive studies on the formation of 
a controlled release system for p-menthane-3,8-diol. As a result, they 
found that the above object can be achieved through the production of a 
controlled release insect pest repellent by blending p-menthane-3,8-diol 
to an ethylene/vinyl acetate copolymer. 
Other objects, features and advantages of the present invention will be 
apparent from the following description. 
The term "repellent" used herein means a molded product having a repellent 
effect. 
DETAILED DESCRIPTION OF THE INVENTION 
As described above, the p-menthane-3,8-diol to be used in the present 
invention involves four isomers, namely, (+)-cis-p-menthane-3,8-diol, 
(-)-cis-p-menthane-3,8-diol, (+)-trans-p-menthane-3,8-diol and 
(-)-trans-p-menthane-3,8-diol. Each isomer has a melting point ranging 
from 57 to 60.degree. C. and is present in the form of a solid at room 
temperature. 
It is possible to use each p-menthane-3,8-diol isomer alone as a solid. 
However, it is preferable to use a mixture of cis- and trans-isomers. When 
a small amount of a p-menthane-3,8-diol isomer is blended with a base 
comprising an ethylene/vinyl acetate copolymer in the form of a solid at 
room temperature, the isomer is frequently non-continuously dispersed in 
the base. Thus, a continuous layer can be hardly formed in this case. When 
a cis-isomer is used together with a trans-isomer at a specific ratio, on 
the other hand, the mixture, which is in the form of a liquid, would be 
continuously dispersed in the base material and thus form a continuous 
layer, even in a small amount. As a result, a more stable controlled 
release system may be more readily achieved. A liquid mixture of isomers 
can be obtained by mixing (+)-cis-p-menthane-3,8-diol with 
(+)-trans-p-menthane-3,8-diol, (+)-cis-p-menthane-3,8-diol with 
(-)-trans-p-methane-3,8-diol, (-)-cis-p-menthane-3,8-diol with 
(+)-trans-p-menthane-3,8-diol and (-)-cis-p-menthane-3,8-diol with 
(-)-trans-p-menthane-3,8-diol, each at a ratio of one component of from 15 
to 85%, preferably 30 to 70% (by weight, the same will apply hereinafter). 
This fact has been found out by the present inventors. When each isomer is 
to be used alone, therefore, it is desirable to add an appropriate liquid 
material so as to facilitate the formation of a continuous layer within 
the base. 
The content of the p-menthane-3,8-diol may appropriately range from 
approximately 5 to 30% of the total composition. When it is smaller than 
5%, it becomes difficult to control a satisfactory repellent effect for a 
long time. On the other hand, a content of p-menthane-3,8-diol exceeding 
30% might cause some problems in molding properties or cost. It is still 
more preferable to adjust the content of p-menthane-3,8-diol within 10 to 
20%. 
As described above, it is one of the requirements for the formation of the 
controlled release system comprising p-menthane-3,8-diol blended in a base 
that the migration rate of the p-menthane-3,8-diol in the base is 
controlled so as to give an appropriate volatilization rate thereof. It is 
required therefore to control the affinity of p-menthane-3,8-diol for the 
base. It is commonly known that the affinity of a substance for a polymer 
depends on the solubility parameter (SP). When the SP of a polymer is 
close to that of a substance, the affinity between these materials is high 
and thus they are highly compatible. When the SP of a substance 
considerably differs from that of a polymer, on the contrary, the affinity 
between them is low and thus they are scarcely compatible. 
When a base comprises a single homopolymer, a controlled release system of 
p-menthane-3,8-diol can be hardly formed, since the affinity cannot be 
controlled as described above. Accordingly, a polymer having two or more 
constituting molecule moieties which are different from each other in the 
affinity for p-menthane-3,8-diol, per molecule, is useful as a base for 
forming a controlled release system. Suitable examples of such a polymer 
involve block copolymers, graft copolymers and random copolymers. Further, 
a blend of a homopolymer having a high affinity for p-menthane-3,8-diol 
with one having a low affinity therefore may be available. In this case, 
however, the dissolution properties of the blend would depend on those of 
each homopolymer. As a result, p-menthane-3,8-diol is dissolved 
preferentially in a homopolymer having a higher affinity therefore. Thus, 
the migration rate of the p-menthane-3,8-diol in the polymer layer becomes 
extremely low. Thus, it is difficult to appropriately control the 
volatilization of p-menthane-3,8-diol from the surface layer, even though 
the migration of p-menthane-3,8-diol in the whole system can be controlled 
on the macro surface at the interface with an incompatible polymer. 
Accordingly, a sufficient repellent effect can hardly be achieved in this 
case. 
When a block, graft or random copolymer having two or more constituting 
molecule moieties differing from each other in affinity for 
p-menthane-3,8-diol per molecule is used as a base, in contrast thereto, 
the volatilization rate of p-menthane-3,8-diol can be controlled by 
appropriately adjusting the kinds and composition ratio of the monomer 
units or the length of each segment. In such a copolymer, the micro-phase 
separation in a molecule has been achieved and each microdomein is highly 
dispersed. Therefore, the p-menthane-3,8-diol molecules added thereto are 
also finely dispersed therein. Thus, the copolymer can exert properties 
which can never been obtained by physically blending homopolymers. That 
is, it is possible to appropriately control the compatibility of a 
copolymer, which comprises a monomer unit whose SP is relatively close to 
that of p-menthane-3,8-diol (or a segment comprising a continuous phase of 
a monomer) with a monomer unit whose SP is considerably different from 
that of p-menthane-3,8-diol (or segment), with p-menthane-3,8-diol so as 
to achieve the controlled release of the repellent component. Furthermore, 
the rate of the controlled release can be satisfactorily controlled by 
adjusting the ratio of, for example, the segments. 
As described above, the repellent component p-menthane-3,8-diol is volatile 
at room temperature. However, it is needless to say that the volatility 
thereof would increase as temperature increases. Thus, it is undesirable 
that the base containing the repellent component has a high molding 
temperature, since the amount of the volatilized repellent component is 
increased thereby. Accordingly, it is required to select a base material 
which has as low a molding temperature as possible and yet shows excellent 
molding properties. 
The present inventors have conducted extensive studies to find out a base 
polymer satisfying the above-mentioned requirements for achieving a 
controlled release system. As a result, they have found out that an 
ethylene/vinyl acetate copolymer, ethylene/acrylate copolymer, 
acrylate/acrylonitrile copolymer, butadiene/acrylonitrile copolymer, 
ethylene/vinyl alcohol copolymer, partially saponified PVA, polyethylene 
glycol/polypropylene glycol copolymer, etc., are effective therefore. They 
have further found out that ethylene/vinyl acetate copolymer is the most 
suitable among these materials, from the viewpoints of the formation of 
the aimed controlled release system and molding properties. 
Accordingly, the ethylene/vinyl acetate copolymer to be used in the present 
invention as a base is a polymer which carries two constituting molecule 
moieties differing from each other in affinity for p-menthane-3,8-diol, 
i.e., an ethylene unit and a vinyl acetate unit, per molecule. The SP of 
p-menthane-3,8-diol is 13.8, while those of the ethylene and vinyl acetate 
units are 8.6 and 11.3, respectively. Namely, the vinyl acetate unit has a 
relatively high affinity for p-menthane-3,8-diol while the ethylene unit 
has a relatively low affinity therefore. Thus, it is possible to establish 
a controlled release system for the repellent component by appropriately 
controlling the constituting ratio between the ethylene and vinyl acetate 
units. When the content of the vinyl acetate unit is elevated, for 
example, a controlled release system having a high affinity for the 
repellent component as the whole can be obtained, which enables controlled 
release of the repellent component for a prolonged period of time. 
The maximum content of the p-menthane-3,8-diol to be added to the 
ethylene/vinyl acetate copolymer varies depending on the content of the 
vinyl acetate unit having a high affinity therefore. Namely, the upper 
limit of the p-menthane-3,8-diol content increases with an increase in the 
content of the vinyl acetate unit. When p-menthane-3,8-diol is added at a 
ratio of, for example, 5%, 10%, 20% and 30% of the total composition, it 
is required to adjust the lower limit of the content of the vinyl acetate 
unit in the ethylene/vinyl acetate copolymer to approximately 15%, 25%, 
30% and 35%, respectively. As described above, the lower limit of 
p-menthane-3,8-diol for achieving the aimed effect is 5%. Thus, it is 
required that the ethylene/vinyl acetate copolymer contains at least 
approximately 15% of the vinyl acetate unit. 
On the other hand, the ethylene/vinyl acetate copolymer shows excellent 
molding properties when the content of the vinyl acetate unit is 
approximately 30% or below. When the content thereof exceeds this value, 
the molding properties of the ethylene/vinyl acetate copolymer are 
deteriorated, which makes the molding difficult. However, an 
ethylene/vinyl acetate copolymer containing 30% or more of a vinyl acetate 
unit can be relatively easily molded by adding another powdery 
ethylene/vinyl acetate copolymer containing about 50 to 70% of a vinyl 
acetate unit thereto. The powdery ethylene/vinyl acetate copolymer can be 
added in an amount up to approximately 30% of the base ethylene/vinyl 
acetate copolymer. Accordingly, a molded product of an ethylene/vinyl 
acetate copolymer containing approximately 40% of a vinyl acetate unit can 
be obtained by adding the maximum amount of the powdery copolymer. 
Therefore, the ethylene/vinyl acetate copolymer to be used as a base in the 
present invention contains the vinyl acetate unit in a content within a 
range of from approximately 15 to 40%. The controlled release of the 
p-menthane-3,8-diol at an aimed volatilization rate for a long time can be 
achieved by varying the content of the vinyl acetate unit within the range 
as specified above so as to control the affinity thereof for the 
p-menthane-3,8-diol. 
The ethylene/vinyl acetate copolymer may further contain other commonly 
used resins such as polyvinyl chloride, chlorinated polyethylene or 
polyethylene, if required. 
The p-menthane-3,8-diol may be blended with the ethylene/vinyl acetate 
copolymer by, for example, (1) adding the p-menthane-3,8-diol to the 
ethylene/vinyl acetate copolymer under stirring and heating so as to allow 
the ethylene/vinyl acetate copolymer to absorb the p-menthane-3,8-diol or 
(2) kneading these materials together on a heated roll, as described 
below. 
Method (1) 
(a) When only an ethylene/vinyl acetate copolymer containing 40% or less of 
a vinyl acetate unit is used as a base resin, the ethylene/vinyl acetate 
copolymer is stirred by mixer under heating at 30.degree. to 40.degree. C. 
and then the p-menthane-3,8-diol is added dropwise thereto to allow the 
copolymer to absorb the p-menthane-3,8-diol. 
(b) When the mixture of an ethylene/vinyl acetate copolymer containing 30% 
or less of a vinyl acetate unit and a powdery ethylene/vinyl acetate 
copolymer containing about 50 to 70% of a vinyl acetate unit is used as a 
base resin, the master pellets of both copolymers are prepared using an 
ordinary granulator, these master pellets are stirred by mixer under 
heating at 30.degree. to 40.degree. C. and then the p-menthane-3,8-diol is 
added dropwise thereto to allow the copolymer to absorb the 
p-menthane-3,8-diol. 
Method (2) 
(a) When only an ethylene/vinyl acetate copolymer containing 40% or less of 
a vinyl acetate unit is used as a base resin, the copolymer is kneaded 
together with the p-menthane-3,8-diol on a heated roll at 50.degree. to 
90.degree. C. to obtain a sheet-type product. 
(b) When the mixture of an ethylene/vinyl acetate copolymer containing 30% 
or less of a vinyl acetate unit and a powdery ethylene/vinyl acetate 
copolymer containing about 50 to 70% of a vinyl acetate unit is used as a 
base resin, the ethylene/vinyl acetate copolymer containing 30% or less of 
a vinyl acetate unit is kneaded with the p-menthane-3,8-diol absorbed 
previously into the powdery ethylene/vinyl acetate copolymer on a heated 
roll at 50 to 90.degree. C. to obtain a sheet-type product. 
The ethylene/vinyl acetate copolymer containing the p-menthane-3,8-diol 
thus obtained may be molded into any form, for example, pellets, sheet, 
net or rod by a molding machine commonly used in the plastics industry. In 
this case, various additives such as colorants, fillers or plasticizers 
may be added thereto, if required. 
In the present invention, p-menthane-3,8-diol may be used together with 
other vegetable essential oils having a repellent effect as repellent 
components. Examples of these vegetable essential oils include peppermint 
oil, laurel oil, pine oil, eucalyptus oil, citronella oil, pennyroyal oil, 
cedar oil, rutaceae oil, white cedar oil, lavender oil, Japanese 
peppermint oil, melissa oil, sage oil, rosemary oil, cinnamon oil and 
clove oil. 
The controlled release insect pest repellent of the present invention thus 
molded in various forms may be used in the following manner depending on 
the form. When molded into pellets, it may be applied to the roots of 
trees as such so as to protect the trees from insect pests. Alternatively, 
it may be charged into an open vessel and hung in, for example, a porch, a 
lavatory, a room corner or a kennel. When molded into a sheet or a net, it 
may be placed in a kennel or wound around a tree. In particular, a 
sheet-type product may be cut into an appropriate size and provided with 
metal fittings so as to give a collar for a dog or cat for exterminating 
insect pests such as a mosquito, flea or mite. A net-type product may be 
used together with a window screen so as to severely prevent insect pests 
from entering into the interior. A rod-type product may be wound around a 
tree or hung at the entrance of a kennel. Furthermore, it may be used as 
farm materials. Namely, it may be used as supports or nets in farms to 
thereby protect crops from insect pests. In the field of sericulture, 
furthermore, invasion of insect pests or the escape of silkworms can be 
inhibited by covering a rearing bed with the controlled release insect 
pest repellent of the present invention in the form of pellets or a sheet.

To further illustrate the present invention, the following Examples will be 
described below, which, however do not limit the present invention in any 
way. Unless otherwise specified, all parts, percents, ratios and the like 
are by weight. 
EXAMPLE 1 
To 100 parts of an ethylene/vinyl acetate copolymer containing 26% of a 
vinyl acetate unit (trade name, Ultrathene UE 634; manufactured by Tosoh 
Corporation), were added 40 parts of chlorinated polyethylene (trade name, 
Daisolac H-135; manufactured by Osaka Soda K. K.), 40 parts of aluminum 
hydroxide having an average particle size of 3 .mu.m and 10 parts of 
(+)-cis-p-menthane-3,8-diol which was employed as a repellent component. 
After uniformly mixing, the obtained mixture was kneaded in a mixing roll 
and formulated into a sheet-type controlled release insect pest repellent 
having a thickness of 1 mm. The persistence of the repellent component 
contained in the sheet-type insect pest repellent thus obtained was 
monitored with the lapse of time (25.degree. C., 65% RH) by gas 
chromatography. The results are as follows. 
______________________________________ 
Time (month) 
0 1 3 6 9 12 
______________________________________ 
Persistence (%) 
100.0 92.7 70.7 59.5 59.1 58.9 
______________________________________ 
EXAMPLE 2 
The procedure of Example 1 was repeated except that the 
(+)-cis-p-menthane-3,8-diol was replaced with a mixture (1:1) of 
(+)-cis-p-menthane-3,8-diol and (-)-trans-p-menthane-3,8-diol to thereby 
give a sheet-type controlled release insect pest repellent having a 
thickness of 1 mm. The persistence of the repellent components contained 
therein was monitored with the lapse of time (25.degree. C., 65% RH) by 
gas chromatography. The results are as follows. 
______________________________________ 
Time (month) 
0 1 3 6 9 12 
______________________________________ 
Persistence (%) 
100.0 85.4 68.3 51.6 39.4 27.2 
______________________________________ 
EXAMPLE 3 
To 100 parts of an ethylene/vinyl acetate copolymer containing 26% of a 
vinyl acetate unit (trade name, Ultrathene UE 634; manufactured by Tosoh 
Corporation), were added 20 parts of an ethylene/vinyl acetate copolymer 
containing 60% of a vinyl acetate unit (trade name, Soarblen CI; 
manufactured by Nippon Synthetic Chemical Industry, Co., Ltd.) and 10 
parts of a mixture (1:1) of (+)-cis-p-menthane-3,8-diol and 
(-)-trans-p-menthane-3,8-diol. After uniformly mixing, the obtained 
mixture was kneaded in a mixing roll and formulated into a sheet-type 
controlled release insect pest repellent having a thickness of 1 mm. The 
persistence of the repellent components contained in the sheet-type insect 
pest repellent thus obtained was monitored with the lapse of time 
(25.degree. C., 65% RH) by gas chromatography. The results are as follows. 
______________________________________ 
Time (month) 
0 1 3 6 9 12 
______________________________________ 
Persistence (%) 
100.0 90.3 66.0 60.7 56.5 52.1 
______________________________________ 
The results of these Examples indicate the following facts. The controlled 
release insect pest repellent of Example 1 wherein an isomer of 
p-menthane-3,8-diol was blended alone with an ethylene/vinyl acetate 
copolymer base showed continuous release of the repellent component by 
portions for approximately 6 months. The controlled release insect pest 
repellents of Examples 2 and 3, each contained a liquid mixture of cis- 
and trans-isomers of p-menthane-3,8-diol as repellent components, showed 
continuous release of the repellent components by portions for 
approximately 12 months. Thus, it is understood that stable controlled 
release systems may be readily formed in the latter cases, compared with 
the one of Example 1 containing a single p-menthane-3,8-diol isomer. 
EXAMPLE 4 
To 100 parts of an ethylene/vinyl acetate copolymer containing 26% of a 
vinyl acetate unit (trade name, Ultrathene UE 634; manufactured by Tosoh 
Corporation), was added 15 parts of a mixture (2:1) of 
(-)-cis-p-menthane-3,8-diol and (+)-trans-p-menthane-3,8-diol which were 
employed as repellent components. After uniformly mixing, the obtained 
mixture was kneaded in a mixing roll and formulated into a sheet-type 
controlled release insect pest repellent having a thickness of 1 mm. The 
persistence of the repellent component contained in the sheet-type insect 
pest repellent thus obtained was monitored with the lapse of time by gas 
chromatography. The results are as follows. 
______________________________________ 
Time (month) 
0 1 3 6 9 12 
______________________________________ 
Persistence (%) 
100.0 93.5 81.2 68.4 60.1 57.8 
______________________________________ 
EXAMPLE 5 
To 100 parts of an ethylene/vinyl acetate copolymer containing 26% of a 
vinyl acetate unit (trade name, Ultrathene UE 634; manufactured by Tosoh 
Corporation), were added 30 parts of an ethylene/vinyl acetate copolymer 
containing 60% of a vinyl acetate unit (trade name, Soarblen CI; 
manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 30 parts 
of a mixture (2:1) of (+)-cis-p-menthane-3,8-diol and 
(-)-trans-p-menthane-3,8-diol. After uniformly mixing, the obtained 
mixture was kneaded in a mixing roll and formulated into a sheet-type 
controlled release insect pest repellent having a thickness of 2 mm. The 
repellent effect of the sheet-type insect pest repellent thus obtained was 
examined by the following method using fleas. 
The sheet was cut into square pieces of a width of 10 mm and provided with 
metallic fittings so as to give a collar for a dog. For comparison, a 
sheet having a thickness of 2 mm was prepared by using the same materials 
except for the repellent components, and similarly formulated into a 
collar for a dog. Each dog collar was allowed to stand under open-air 
conditions at room temperature for a definite period. Then, each collar 
was put on a dog for a week and the time required that the repellent 
effect made fleas in the hair of the dog migrate onto the surface of the 
hair was determined. When fleas completely migrated to the surface of the 
hair, the dog was brushed so as to remove the fleas. One week after the 
application of the collar, the conditions were observed again. 
The persistence of the repellent component contained in the sheet-type 
insect pest repellent thus obtained with the lapse of time as well as the 
repellent effect thereof on fleas are as follows. 
Change in persistence with the lapse of time: 
______________________________________ 
Time (month) 
0 1 3 6 
______________________________________ 
Persistence (%) 
100.0 94.2 84.0 72.0 
______________________________________ 
Time required for migration of fleas from the skin to the surface of the 
hair: 
______________________________________ 
Time (month) 
0 1 3 6 
______________________________________ 
Example 1 hour 1 hour 1.5 hours 
2 hours 
Comparative 
No No No No 
Example migration migration migration 
migration 
______________________________________ 
Conditions 1 week after application of collar: 
______________________________________ 
Time (month) 
0 1 3 6 
______________________________________ 
Example No fleas No fleas No fleas 
No fleas 
Comparative 
Fleas Fleas Fleas Fleas 
Example in hair in hair in hair in hair 
______________________________________ 
Thus, the collar containing the repellent components, which had been 
allowed to stand for 6 months under open-air conditions, made fleas in the 
hair of the dog completely migrate onto the surface of the hair within 2 
hours. Thus, it was proved that the repellent effect was controlled for a 
long time. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.