Note: Descriptions are shown in the official language in which they were submitted.
~L~239~79
PROCESS FOR PREPARING INSECT-REPELLENT AND
INSECTICIDAL FILM
Background of the Invention
Field of the Invention:
This invention relates to a process for preparing an
insect-repellent and insecticidal synthetic resin film
wherein a pyrethroid insecticide is used as an insect-
repellent and insecticidal agent.
Description of the Prior Art:
Insect-repellent and insecticidal films are available
in various fields such as in packaging fruits during
transportation to thereby prevent insect damage, in
e packaging clothes to thereby prevent eye damage and in
laying under totem mats or carpets to thereby prevent
tick damage.
Insect-repellent and insecticidal films may be roughly
classified into two types. One includes those comprising
an insecticide inserted into laminated synthetic resin or
paper sheets while the other includes those prepared by
coating or impregnating a synthetic resin or paper sheet
with an insecticide.
The thickness of an lnsect-repellent and insecticidal
material comprising an insecticide inserted into laminated
sheets is limited so that it is not possible to prepare a
thin-gage film of this type.
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On the other hand, an insect-repellent and insecticidal
film prepared by coating a synthetic resin or paper sheet with
an insecticide exhibits an insect-repellent and insecticidal
effect only in a short period since the insecticide is directly
exposed to air. With regard to impregnated films, paper films
of this type have been prepared but it is difficult to impregnate
a synthetic resin with an insecticide. Therefore no film has
been prepared by molding a mixture of a synthetic resin compound
and an insecticide.
Thus it has been required to develop an insect-repellent
and insecticidal film prepared by molding a mixture of a synthetic
resin compound and an insecticide, which exhibits a uniform insect-
repellent and insecticidal effect and shows an appropriate bleed-
in of the insecticide on its surface.
Summary of the Invention
Under these circumstances, the present invention provides
a process for preparing an insect-repellent and insecticidal film,
which comprises:
forming an inclusion compound consisting of a pyrethroid
insecticide included in cyclodextrin or a starch hydrolyzate con-
twining cyclodextrin;
drying and powdering the obtained inclusion compound;
melt-blending with a synthetic resin compound such
that the resulting blend contains 0.1 to 50 % by weight of the
inclusion compound-containing powder.
poulticing the obtained blend and molding the pellets
optionally with an appropriate additional amount of the synthetic
resin into a film. In this process, the pyrethroid insecticide
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I ~3~5~
i.e. an insect-repellent and insecticidal agent is used in the
form of an inclusion compound included in cyclodextrin to unit
firmly mix the insecticide with the synthetic resin and to give an
appropriate bleeding or ooze of the pyrethroid insecticide on
the surface of the film.
The present invention also provides a synthetic resin
film which can be prepared by the above method.
Detailed Description of Preferred Embodiments:
The pyrethroid insecticide used in the present invention
includes the following:
allethrin ~dl-3-allyl-2-methyl-4-oxo-2-cyclopentenyl
dl-cis/trans-chrysanthemate]:
IH3
H C C
3 \ /
/C=CH -HO SHEA -C- O -HO C- SHEA- OH- SHEA
H3C I H2C C- O
H3C SHEA
phthalthrin [(1,3,4,5,6,7-hexahydrol-1,3-dioxo-2-isoindolyl)
methyl dl-cis/trans-chrysanthemate]:
1~3~579
`C=CIl-11C--C~-C-o-c~t.-N~ I,
C 0 5 -
/ \ O
H3C C~!3
resmethrin [(bouncily furyl)methyl dl-cis/trans-
chrysanthemate]:
C~Ctl--HC--C~--C--o~ C',t.--c--C~t
C O HO C--C~
H3C C~3 0
uramethrin [(5-(2-propinyl)-2-furyl)methyl dl-cis/
trans-chrysanthemate];
I I
.~,3c\ 11
C= Cluck C~,--C--o--c1~.--C C
11 C/ \ /
3 C O C}~,2-C-
~3C Ho
phenothrin [(3-phenoxybenzyl d-cis/trans-chrysan-
the mate]:
1~39579
I
C=~C!l--~1C--C,'l--C--o--C~
C/ \ / and
C O
H3C C~3
permethrin [3~phenoxybenzyl dl-cis/trans-3-(2,2-
dichlorovinyl(2,2-dimethyl-1-cyclopropanecarboxylaate]:
3=C~--HC_c~--c--o-c~-~ o
I o
~3C C~3
In the process of the present invention, a pyrethroid
insecticide is used as an insect-repellent and insecticidal
agent since it exhibits an excellent effect as well as a
low toxicity and is available over a wide range. Further
it can be readily included in cyclodextrin to thereby form
at Jo Swerve
a clathratc compound. Furthermore it is relatively stable
at high temperatures so that it can be mixed with a synthetic
resin compound for molding.
The cyclodextrin used in the present invention is a
particular dextrin wherein D-glucose molecules form a ring
by binding to each other through an ~-1,4 linkage and
characterized by having a doughnut-like molecular structure
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~.239579
with an inner cavity of 6 to 10 A in diameter. Cyclodex-
inn can be classified into three types it - and
y-cyclodextrins) depending on the number of constituting
D-glucose units. Any of these types can be used in the
present invention. For example, ~-cyclodextrin is in the
form of a white crystalline powder and represented by the
molecular formula (KIWI), has a molecular weight of
1135 and melts at 300 to 305C (doe.).
In the process of the present invention, the
cyclo~extrin may be substituted by a starch hydroly~ate
containing cyclodextrin obtained by various methods. For
example, a starch hydrolyzate of the above type can be
obtained as an intermediate in the preparation of
cyclodextrin by hydrolyzing starch with cyclodextrin
synthetase produced by a microorganism belonging to the
genus Bacillus. The process for the preparation of the
starch hydrolyzate will be further described in detail.
A starch solution is adjusted to a pi value of 10,
homogeneously gelatinized and allowed to cool. Then
cyclodextrin glycosyltransferase, which is a fermentation
product of a microorganism selected from Bacillus No. 13,
No. 17-1, No. 38-2, No. 135 and No. 169 strains, as an
optimum pi value in a basic region and exhibits a high
thermal stability, is added thereto to effect a reaction.
The reaction mixture is heated to inactivate the enzyme
~L~39~9
and allowed to cool. Then it is adjusted to a pi value
of 5Ø Commercially available glucoamylase is added
thereto to thereby decompose unrequited matters.
Subsequently the mixture is filtered in a convent
tonal manner and concentrated to give a cyclodextrin
concentration of approximately 40 or above. A small
amount of seed cyclodextrin is added to the concentrate
and allowed to stand. The cyclodextrin thus precipitated
is filtered and dried to give ~-cyclodextrin. The
filtrate obtained at this stage is the aimed starch
hydrolyzate (cf. Japanese Patent Publication No. 43897/
1977)
. ~,"~ .
The Bacillus No. 13, No. 17-1, No. 38-2, No. 135 and
No. 169 strains as described above have been deposited
with the Fermentation Research Institute of the Agency
of Industrial Science and Technology and referred to as
FORM No. 611, No. 612, No. 614, No. 617 and No. 618,
respectively.
A commercially available starch syrup containing
cyclodextrin prepared by repurifying the above mentioned
filtrate with an ion exchange resin followed by
concentration may be used in the process of the present
invention.
The starch hydrolyzate containing cyclodextrin used
in the present invention is not restricted to those
~39~ 8765-9
obtained by the above processes but a starch hydrolyzate con-
twining or ~-cyclodextrin or a mixture thereof obtained
by any process may be employed.
The synthetic resin compound used in the present invent
lion should have a low melting point. Because the pyrethroid
insecticide would decompose above 180C although it is heat-resis-
lent. Some synthetic resins are molded at a temperature higher
than 180C so that it is necessary to select a synthetic resin
compound which can be molded at a temperature lower than the
decomposition point of the pyrethroid insecticide. Thus synthetic
resin compounds such as a polyolefin resin, a flexible polyvinyl
chloride resin or a polyvinyl acetate resin may be employed.
For forming the inclusion compound, the pyrethroid
compound and cyclodextrin (which may be contained in a starch
hydrolyzate) which is usually slightly wet are mixed and warmed
at a temperature, for example, around 50C. Preferably, from
about 10 to about 20 parts by weight of the pyrethroid compound
and from about 80 to about 90 parts by weight of cyclodextrin
are used, each per 100 parts by weight of the total.
The dried and powdered inclusion compound preferably
in an amount of 10 to 50 parts by weight is melt-blended with
90 to 50 parts by weight of the synthetic resin, each per 100
parts by weight of the resulting blend.
Preferably, the final synthetic resin composition just
before being formed into a film comprises from about 0.6 to
about 3 % by weight of the pyrethroid compound included in from
about 3.4 to about 17 % by weight of cyclodextrin (which may of
course be a starch hydrolyzate containing cyclodextrin), and from
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1~3~g~ q)~`3
about 80 to about 96 % by weight of the synthetic resin. This
composition is substantially the same after being formed into a
film.
Now exclmples of the process for the preparation of the
insect-repellent and insecticidal film of the present invention
will be given.
Example 1
85 parts by weight of ~-cyclodextrin was added to 15
parts by weight of allethrin and the mixture was stirred at 50C
for one hour. The inclusion compound consisting of allethrin
included in cyclodextrin thus obtained was ground with a vacuum
drier at 60C to give a power of 150 mesh or below. 50 parts
by weight of this powder was molten together with 50 parts by
weight of a flexible
aye-
1239~7~3
68765-9
polyvinyl chloride compound. The molten mixture was poulticed by
cold-cutting. Then 10 parts by weight of the pellets were mixed
with 90 parts by weight of the flexible vinyl chloride compound
and the mixture was molded into a film by calendering.
Example 2
90 parts by weight of ~-cyclodextrin was added to 10 parts
by weight of phthalthrin and the mixture was stirred at 50C for
one hour. The inclusion compound consisting of phthalthrin
included in cyclodextrin thus obtained was ground with a spray
drier at 60C to give a powder of 150 mesh or below. 30 parts by
weight of this powder was molten together with 70 parts by weight
of a flexible polyvinyl chloride compound. The molten mixture was
poulticed by hot-cutting. Then 20 parts by weight ox the pellets
were mixed with 80 parts by weight of the flexible polyvinyl
chloride compound and the mixture was molded into a film by
extruding.
Example 3
85 parts by weight of a starchhydrolyzate containing 50~
of - and Y-cyclodextrins was added to 15 parts by weight of
resmethrin and the mixture was stirred at 50C for one hour. The
inclusion compound consisting of resmethrin included in cycle-
dextrin thus obtained was ground with a vacuum drier at 60C to
give
~23~5~ 68765-9
a powder of 150 mesh or below. 20 parts by weight of this powder
was molten together with 80 parts by weight of polyethylene
pellets. The molten mixture was molded into pellets by cold-
cutting and subsequently into a film by calendering.
Example 4
85 parts by weight of a starch hydrolyzate containing 15%
of - and ~-cyclodextrins was added to 15 parts by weight of
furamethrin and the mixture was stirred at 50C for one hour. The
inclusion compound consisting of furamethrin included in cycle-
dextrin thus obtained was ground with a spray drier at 60C to give powder of 150 mesh or below. 10 parts by weight of this powder
was molten together with 90 parts by weight of a polyvinyl acetate
compound. The molten mixture was poulticed by underwater-cutting.
40 parts of the pellets were mixed with 60 parts by weight of the
polyvinyl acetate compound and the mixture was molded into a film
by extrusion.
Example 5
80 parts by weight of ~-cyclodextrin was added to 20 parts
by weight of phenothrin and the mixture was stirred at 50C for one
hour. The inclusion compound consisting of phenothrin included in
cyclodextrin thus obtained was ground with a drum drier to give a
powder of 150 mesh or below. 10 parts by weight of this powder
was molten
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~2~9S7~
together with 90 parts by weight of an ethylene-vinyl
Ed.- CO p on l`
acetate compound The molten mixture was molded into
pellets by sheet-cutting and subsequently into a film
by extrl1ding.
Example 6
A film was prepared by following the procedure of
Example 5 except that the phenothrin was substituted by
permethrin.
Each insect-repellent and insecticidal film thus
prepared exhibited a uniform insect-repellent and
insecticidal effect. In addition, the appropriate
bleeding of the insecticide on the surface of the film
allowed this effect to persist for a prolonged period.
These insect-repellent and insecticidal films thus
obtained may be used in the following manners.
Application Example 1
These films are available in packaging fruits during
transportation, in particular in packaging bananas,
oranges or apples to be transported for a prolonged
period, e.g., for import or export, to thereby prevent
insect damage.
Application Example 2
These films are available in packaging cut or
potted plants to be transported or ornamented to thereby
prevent insect damage.
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~39~9 68765-9
Application Example 3
These films are available in packaging clothes to be laid
away for a long period to thereby prevent moth damage.
Application Example 4
These films are available in laying under totem mats or
carpets to thereby prevent thick damage.
Application Example 5
These films are available in packing bags for cereals to
prevent insect damage by its niticidal effect, thereby extending
lo the shelf-life of the contents.
As described above, the process for preparing an insect-
repellent and insecticidal film according to the present
invention, which comprises forming an inclusion compound
consisting of a pyrethroid insecticide included in cyclodextrin,
mixing the inclusion compound with a synthetic resin compound and
molding the mixture into a film, can give a film exhibiting a
uniform insect-repellent and insecticidal effect because of the
uniform dispersion of the insecticidetherethrough. further the
insect-repellent and insecticidal effect of this film can persist
for a prolonged period because of the appropriate bleeding of the
insecticide on its surface. The desired intensity of the insect-
repellent and
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~2~9~
insecticidal effect can be obtained by selecting an
appropriate pyrethroid insecticide and/or varying the
amount of the insecticide or pellets depending on the
insects to be exterminated. In addition, this film
can be molded to give any desired thickness. For
example, even a thick film like a plate can be prepared.
Thus the process of the present invention is highly
effective.
