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2,410,101
Petented Oct. 29,
UNITED STATES PATENT OFFICE
WAX-FREE PYRETHRIN‘ SOLUTIONS '
Joseph D. Park, Wilmington, Del., and William W.
Rhodes, Westtown, Pa., assignors to Kinetic
Chemicals, Inc., Wilmington, Del., a corpora
tion of. Delaware
No Drawing. Application January 6, 1944,
Serial No. 517,260
3 Claims. (Cl. 167-24)
2
1
waxes took place at room temperature. .The so
lution was then ?ltered through Filter-eel on ?l
ter cloth at room temperature in a closed sys
tem, using the pressure of the solvent, with addi
This invention relates to solutions 01’ pyrethrins
which are stable in the presence of iron.
Solutions of pyrethrins, the active ingredients
of pyrethrum ?owers, are mixed with liquids vola
tilizable at normal atmospheric temperatures and 5 tional nitrogen pressure if desired. The insoluble
material removed amounted to 10% of the total
enclosed in containers having ori?ces through
weight of extract used. Part 01 the ?ltered solu
which the contents may be discharged at will as
tion was then placed in another pressure tube in
a ?ne spray. The containers are usually made of '
contact with iron. After ?ve days’ standing, pre
iron because the volatility of the propellant liq
uid requires a container capable of withstanding 10 cipitation of dark and gummy substances began
to take place on the iron while the original ?ltered
pressure. The propellant solutions are usually
solution in another pressure tube in the absence
made up from standard pyrethrin extracts and,
or iron remained unchanged. A portion or this
after mixture with the propellant liquid, contain
original ?ltered solution was then subjected to
about 93% by weight of CClzFz as the propellant,
about 1% oi.’ pyrethrins 1 and 2, about 4% kero 15 cooling at -—15° for one-half hour and ?ltered at
the same temperature. Precipitation of insoluble
sene and inert ingredients, and about 2% sesame
waxes and fatsamounting to an additional 10%
oil. The mixture of the pyrethrin solution with
of the total extract used was obtained. This so
CClzFr usually results in the precipitation of a
lution remained clear in the presence of iron
waxy material which is ?ltered oil to prevent it
from clogging the ori?ce of the container. The 20 even- after a year’s standing. This experiment
indicates the advantage of our invention.
?ltrate, when enclosed in an iron container, pre
cipitates additional amounts of waxy material up
Example II
on standing. These additional amounts of waxy
Kerosene
extract
of pyrethrum oleoresin ob
material are sufficient to clog the type of ori?ce
25 tained by extraction of pyrethrum ?owers with
used to produce an effective spray.
ethylene dichloride was made up to the stand
It is an object of this invention to prepare pro
ard CClzFz aerosol solution as given in Example
pellant solutions of pyrethrins which are stable
I. Immediate precipitation of waxes and resin
in the presence of iron. Other objects or the
ous material took place. However, treatment of
invention are in part apparent and will be in part
30 this solution by chilling to —15° for‘ one-halt
set forth hereinafter.
The objects of the invention are accomplished, _ hour and ?ltration at this temperature, brought
about wax elimination to such an extent that
further precipitation did not occur in the pres
ence of iron. Various commercial grades 01' 20%
generally speaking, by subjecting the propellant
solution to a temperature between about —10°
and about —30° C. until the wax precipitation has
ceased, and ?ltering the wax from the chilled 35 pyrethrum extracts when used in CClzFz insec
ticidal solutions behaved similarly. Subsequent
solution. The solution so prepared is stable in
cooling for one-half hour and ?ltering at —,-15°
the presence of iron.
C. brought about the elimination of any further
The following examples illustrate the invention
wax precipitation when cooled to -—20° C. or
but do not limit it.‘
'
40 when allowed to remain in iron cylinders for
Example I
months. In the practice of our invention the
loss of the active ingredients pyrethrins I and 11
De?nite amounts of a commercial grade of par
did not exceed over 1% of the total active ingre
tially dewaxed 20% kerosene extract of pyreth
dients
originally present in the extract used.
rum ?owers containing sesame oil were placed
A very satisfactory operating temperature is
in a high-pressure glass vessel and the vessel
about —15° C., at which a cooling time of about
then evacuated. Sufficient CClzF: was then add
thirty
minutes produces an e?lcient precipitation
ed to make an insecticidal solution of the follow
of
waxes
to produce a. ?ltrate stable in the pres
ing composition:
'
ence of iron. Chilling and ?ltering may be car
Per cent by weight
50 ried out batchwise or continuously. Various con
CClzF:
__ 93
centrations of pyrethrins in the propellant solu
Pyrethrins I and II_____________________ __
1
Sesame oil.
Inert+kerosene
'
_____________ __- _________ __
tions may be used.
2
Immediate precipitation of insoluble fats and
'
A particular advantage of the invention is that
4
propellant solutions of pyrethrins and propellants,
55
particularly CClzFa, are prepared which are sta
2,410,101
3
ble in the presence of iron. Insecticide contain
ers having spray ori?ces contain these solutions
without the precipitation of deleterious amounts
of waxes‘ The propellant solutions before the
treatment contain a coloring matter which pro
duces undesirable green stains on cloth. An ad
4
2. The process of preparing propellant solutions
of pyrethrins in CClaFa which are stable in the
presence of iron, which comprises mixing a com
mercial grade of a kerosene extract 01' pyrethrum
?owers with (301215’: in an amount su?‘lcient to
make an insecticidal solution containing about
93% by weight of CClzF'a, chilling the resultant
ditional advantage oi’ the invention is that this
solution to between about ——10° C. and about
treatment also removes that coloring matter.
—30° C. until wax precipitation has ceased and
As many apparently widely different embodi
then separating the chilled solution from the pre
ments of this invention may be made without
cipitate.
'
departing from the spirit and scope thereof, it is
3. The process of preparing propellant solutions
to be understood that we do not limit ourselves
to the speci?c embodiments thereof except as de
of pyrethrins in CClzFa which are stable in the .
presence of iron, which comprises mixing a com
?ned in the appended claims.
15 mercial grade of a kerosene extract of pyrethrum
We claim:
1. The process of stabilizing a propellant so
?owers with CClaFs in an amount su?lcient to
make an insecticidal solution containing about
lution of pyrethrins in CCiaF: which solution nor
mally tends to precipitate waxes and fats in the
93% by weight oi CClaFz, chilling the resultant
presence oi! iron at temperatures above -20° 0.,
solution to about —15° C. until wax precipitation
which comprises the steps 01' chilling the solution 20 has ceased and then separating the chilled solu
tion from the precipitate.
to between about —-10° C. and about —-30° C.
until wax precipitation has ceased and then sep
JOSEPH D. PARK.
arating the chilled solution from the precipitate.
WILLIAM W. RHODES‘.
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