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Патент USA US2404698

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Patented July 23, 1946
wrap STATE/S PATENT orricc
2,404,898 '
Alfred Dreyling, South River, N. 3., assignor to
E. I. du Pont de Nemours & Company, Wll-
mlngton, Del, a corporation of Delaware
No Drawing. Application January 4, 1945,
Serial No. 571,357 "
10 Claims.’ (Cl. 167-30)
since only the amount required needbe applied
This invention relates to improved insect re
pellents and more particularly to insect repellent
thus distinguishing favorably from liquid re
pellent where'there is greater wastage due to‘
the application of excess material. A further ob
Insect repellent compositions presently avail
able are widely used with considerable e?‘ective GI iect is the provision of a jelly-like insect repellent
which a?’ords greater ease of application and
'ness, especially in combating. various types of
which is readily removed by washing with soap
mosquitoes. Great quantities ‘of these materials 1
and water. A further object is the provision of
are used by the armed forces operating in trop
insect repellents which are stable for extended
ical. zones where mosquito control is particularly
imperative. These compositions are generally
storage periods and atslow and high tempera
tures. A still further object is the provision of
employed in liquid form. In this fonn, how
insect repellent compositions which may be pack
‘ever, they are characterized by a serious defect
aged in durable containers such as collapsible
in that the period of eiiectiveness is too short.
tubes thereby avoiding breakage during shipping
' Ordinarily the liquid repellent compositions are
effective vi’or less than 3 hours. Application, han 15 and storage handling, such as encountered with
a" and shipping, wastage and undesirable
glass containers as generally used with liquid
repellents.v Other objects will appear as the de
stickiness also suggest the need for improve
scription of the invention proceeds.
ments in such products. Attempts have been
These objects are accomplished in accordance
made to prolong the effective period by additive
edients designed to retard the volatilization
with the present invention by means of a com
position of jelly-like consistency comprising‘ at
rate of the active repellent components. Partial
least one component repellent to insects and a
success as been achieved by preparing the com
plurality of at least partially immiscible cellu
positions as emulsions or gels which may include,
water soluble colloids such asvgum tragacanth,
lose derivatives, selected from the group consist
waxes, oils and cellulose esters. However, pre 25 ing of cellulose esters, and cellulose ethers.
vious products of this type are objectionable be
The follo
examples are given by way of
cause of the large amounts of additive ingredi
illustration only and no limitations are intended
ents required to form gels and because of ap
thereby except as indicated in the appended
pearance, excessive dirt collection, stickiness,
oiliness, or instability during extended storage or 30
Example 1
at high temperatures where there is a tendency
' .
Per cent by weight
to liduefy or at low temperatures where there may
Ethyl cellulose _________________________ __ 2.7
be a tendency to crystallize.
composition 01’ jelly-like consistency.
This invention has as an object the provision of .
an improved insect repellent of jelly-like con
Another object is the provision of an ‘
Cellulose acetobutyrate _________________ __
Proplyene glycol monostearate___________ __
Dimethyl phthalate ____________________ _- 55.8
2-ethyl hexane-1,3-dioi (Rutgers 612) ____ __ 18.6
insect repellent Jelly which does not cause the
Indalone 1
skin to draw or stiffen Another object of the
invention is the provision of an improved insect
repellent which is characterized by e?ectiveness 40
1 Alpha, alpha dimethyl alpha carbobutoxydlhydro
vfor prolonged periods of time. Another object
is the provision of an insect repellent jelly which .
is non-irritating to the skin. Another object is
the provision of an improved insect repellent
\ composition which permits the use of minimum
amounts of additive non-repellent components,
thus a?ording maximum protection against in
sect attacks. A iurther object is the provision
of an insect repellent composition of smooth,
gamma pyrone prepared by condensing‘ butyl oxalate with
mesityl oxide.
The ethyl cellulose used in this composition
had a viscosity of 40,000v cps. determined in 5%
concentration in a solvent vehicle consisting of
80 parts of toluene and 20 parts or ethyl alcohol.
The ethoxyl content of the ethyl cellulose was
46.8 to 48.5%. .
and clothing with resultant unsightly marring
The viscosity of a 20% solution of the cellulose
acetobutyrate dissolved in acetone was about 38"
determined in accordance with A. S. T. M. pro
and in the case of some fabrics, a partial destruc
tion. A further object is the provision of an im
cedure D-301-33.
2500 centipoises.
Y, jelly-like consistency which eliminates accidental 50
, spilling (as in the case of liquids) on furniture
proved insect repellent jelly which avoids waste 55
This corresponds to about
The composition was prepared by charging the -.$
ingredients intoa paddle type mixer and agitat
speci?cations D-301-83.
ing until a homogeneous mixture was secured.
about 34,400 centipoises.
This product likewise, exhibited properties sim
The resulting composition had a smooth jelly
like consistency. Its mosquito repelling proper
ilar to those described for Example 1.
ties were satisfactory and it was found that its
effectiveness in this respect was more than dou
bled in time as compared to the conventional
“Example 5
__. .
vliquid repellent containing the same active in
This corresponds to
Percent by weight
Ethyl cellulose ____ _-__ _________________ _-
Also it was observed that a lighter
3.0 .
Cellulou acetate .._‘. ____________________ __
l 2.5
application could be used and that the objection 10 Propylene glycol di-stearate ____________ _.~v 0.5
Dimethyl phthalate __________________ _..'_. 56.4
able oily condition common to the liquid repellent
z-ethyl hexane-1,3-diol____________ -_'.'.___ 18.8
was eliminated in the new product. Further
' l’ndalnne
more, due to the discontinuous nature of the ap
plied ?lm as provided through the use of the two
incompatible “or immiscible cellulose derivatives, 15
there was no drawing or sti?ening oi’ the skin.
The ethyl cellulose used in this composition
was of the same type as described in Example 1
Example 2'
and the cellulose acetate of the type described
‘Percent by weight
Ethyl cellulose ______________ -1 ________ __
Cellulose acetobutyrate in-“ _________ __
Dimethyl phthalate ____________________ __
2-ethyl hexane-1,3-diol (Rutgers 612) _____
Indalone ____________ _; ________________ __
. °1oo.o
It will be noted that this composition is simi
' lar to Example 1, except that the propylene gly
col monostearate has been omitted.
The resulting‘ properties are also similar to Ex
ample 1 and exhibit comparable superiority in
the essential features including prolonged effec
tiveness after application to the skin.
Example 3
in Example 4.
The product 01' this example also airorded the
desired properties previously described.
In addition to the cellulose derivatives‘dis
closed in the preceding examples, other cellulose
esters, mixed esters or ethers such as cellulose
acetopropionate and benzyl cellulose which are
soluble in organic solvents may also be used, pro
vided there is substantial incompatibility or im
miscibility between the cellulose derivatives, 9.,
condition which represents a basic requirement
30 for the success of the present invention. In gen
eral, it is. preferred to employ two cellulose de
rivatives which are substantially incompatible or
immiscible in the ?nal ?lm and to use such ma
terials in approximately equal amounts.
35 proportion may be varied considerably but it
Percent by weight
Ethyl cellulose ________________________ __
Cellulose nitrate ___" _________ _... ________ __
Dimethyl phthalate ___________________ __
2-ethyl hexane-1,3-diol ________________ __
Indalone ____________________________ __'__
must be maintained in such relationship that a
final ?lm which is discontinuous in character
will result.
The viscosity characteristic of the cellulose de
40 rivatives used in the products of the invention is
important. It is necessary that only high vis
cosity types be employed to a?’ord the desired
consistency in the ?nal product and maintain
the maximum initial e?'ectiveness in repellent
The ethyl cellulose used in this composition 45 action by including only the minimum in non-ac
tive ingredients. In Example 1‘, it is shown that
was of the same type as that described in Ex
a cellulose acetobutyrate with a viscosity char
acteristic ofabout 2500 centipoises determined
The cellulose nitrate had a nitrogen content
in a 20% solution in acetone may be used satis
of about 12% and a viscosity characteristic 'of
887 seconds determined in accordance with the 50 factorily. However, in‘ order to meet the basic
conditions of proper consistency in the ?nal
procedure described in A. S. T. M. Spec. D-301-33.
ample 1.
Formula A. This corresponds to about 330,000
product combined with low non-repellent ingre
dient content, it is necessary when using one cel
lulose derivative oi’ this relatively low viscosity
This product exhibited properties similar to 55
characteristic‘to include as the other cellulose
those described for Example 1.
derivative one which has a much higher viscos
Example 4
Percent by weight
Cellulose acetate ______________________ __
Cellulose nitrate ______________________ __
Glyceryl di-stearate _______________ _______
Dimethyl phthalate _______ -3. ___________ __
2-ethyl hexane-1,3-dio1 ________________ _-
Indalone____; _______ ___ _______________ -c-
The cellulose nitrate used in this composition
was of the same type as that described in Ex
ity characteristic such as suggested" in Example 1
where the second cellulose derivative is ethyl cel
lulose with a viscosity many times higher than
00 that 01' the cellulose acetobutyrate.
In general, the combined cellulose derivative
content should be about 5 to 6% by weight of the
total composition. The preferred viscosity of the
?nal product is about’ 300,000 centipoises al
though suitable compositions may be prepared
with viscosities between about 200,000 and 500,000
centipoises. The total cellulose derivative con
tent may be' varied preferably from about 1% to
10% by weight of the total composition depend
70 ing upon the viscosity characteristic oi! the cel
The cellulose acetate had a combined acetic
lulose derivatives. Thus if dynamite type cellu
acid content of about 55% and a viscosity of
lose ni-trate which has a very high viscosity char
ample 3.
about 100 seconds determined on a 20% concen
acteristic is used, the amount of cellulose deriva
tration of the cellulose acetate in acetone and
_ using the procedure described in A. S. T. M
tive may be as little as about 1% and still main
tain the desired gel-like consistency. The proper
more than double that or the conventional liquid
type insect repellents. The improved gel-like re.‘
pellents are distinguished by ease oi application,
consistency may likewise be maintained with
amounts of cellulose derivatives as high as about
25% with proper adjustment in the use of the
reduction in greasy feel and avoidance 01' wastage
lower viscosity material. The higher concentra
tions of cellulose derivatives tend to reduce the 5 since no excess is applied as in the case of the
liquid products. Problems of spillage, handling
overall repellent eilectiveness and it is therefore
and storage such as encountered with liquid
preferred to employ concentrations of cellulose
products which are frequently packaged in glass
derivatives of not over about 6% for most pur
containers are avoided in the new composition
since collapsible metal tubes are satisfactory con
The examples include three components hav
tamers. Marrmg of furniture and destruction of
ing insect repellent properties since this combi
certain fabrics wnichare attacked by some repel
nation (dimethyl phthalate “Rutgers 612” and
ingredients through accidental spilling are
“Indalone" in the ratio of 3:1:1) has already
avoided with the compositions of the present in
demonstrated its effectiveness in the ?eld, par
The improved repellents are stable at
ticularly as a mosquito repellent. ‘However, for 15 vention.
temperatures for extended storage
some purposes, this ratio may be varied consid-‘
not crystallize or 'liquei'y at tem
erably or only one or if desired two of these com
perature extremes. They are readily removed by
ponents may be employed. For example, di
washing with soap and water.
methyl phthalate has proven to be quite useful
It is apparent that many widely different em
as a repellent and may be substituted wholly for
bodiiments or the invention may be made without
the other repellent components. Also, other ma
departing from the spirit and scope thereof; and,
terials haying properties repellent to insects may
it is not intended to be limltedvexcept
be substituted for or used in conjunction with the’
as indicated in the appended claims.
repellent components previously suggested.
In the examples, the cellulose derivatives are
soluble in at least one of the repellent compo
nents, particularly the dimethyl phthalate and
consequently when agitated in this described
medium become colloided toform the jelly-like
I claim:
1. A non-aqueous insect repellent composition
of gel-like consistency substantially free from
highly volatile solvents comprising a plurality of
cellulose derivatives selected from the group cone
sistmg of cellulose esters and cellulose ethers and
consistency described. The addition of other 80 at lea-st one non-volatile insect repellent which is
solvents which may if desired be of the more vol
a solvent for the cellulose derivatives separately,
atile type is not precluded since the'invention is
operable under such conditions provided the
amount of added solvent does not destroy the de;
the said cellulose derivatives being incompatible
when combined in the said repellent whereby a
consistency is obtained.
sired jelly-like consistency and provided also that 35 gel-like
2. Thecomposltion of claim 1 in which the cel
' the solvent added does not destroy the incompat- .
lulose derivatives are ethyl cellulose and cellulose
ibility or the cellulose derivatives.
Some of the preceding examples provide for the
use of glyceryl di-stearate or ‘propylene glycol
3. The composition or claim_ 1 in which the
insect repellent is dimethyl phthalate.
di-stearate. The use of these ingredients is on 40
' ‘l. The composition of claim 1 in which one of
tional but they are of advantage in rendering
the composition more easily removed by washing _ the cellulose derivatives is ethyl cellulose and the
other is a cellulose ester.
with soap and water. Furthermore, they con
5. The composition or claim 1 in which the
tribute somewhat in reducing the objectionable
?nal viscosity is between 200,000 and 500,000 cen
greasy appearance caused by certain of the re
pellent components.
6. The composition of claim 1 in which the cel
The products of the invention are generally
lulose derivatives are present in an amount be
useful for application to exposed portions of the
tween about 1%, and 10% by weight of the total
skin for the purpose or repelling insects and
more particularly various types of mosquitoes. 50 composition.
'1. The composition of claim 1 in which the’
Thus the compositions ?nd particular utility in
cellulose derivatives are present-in an amount of
tropics especially in the armed forces stationed
about 6% by weight of the total composition.
in such areas under circumstances where there
is very little or no other protection against mos
8. The composition or claim 1 in which the cel
55 lulose derivatives consist or ethyl cellulose and a
siellulose ester in approximately equal propor
The unique results obtained in the improved
products as afforded largely through the discon
9. An insect repellent composition or gel-like
tinuous nature of the applied ?lm may be attrib
consistency comprising dimethyl phthalate, 2
uted to the combination of a plurality of cellu
hexane-1,3-diol, Indalone, ethyl cellulose,
lose derivatives which are at least partially in
cellulose‘ acetobutyrate and propylene slycol
compatible or immiscible with each other in the
?nal ?lm thus providing discontinuity. This
10. An insect repellent composition of gel-like
combination also contributes to the “shortness”
consistency having the following composition by
of the gel thus improving application‘ properties.
The gel-like structure of the cellulose derivative
colloids function to retard volatillzation of the
active repellent components thereby markedly
prolonging the effectiveness of the insect repel
lent properties.
The new compositions are characterized by 70
numerous important advantages chief of which
is the desired prolongation of the e?ectiveness
ai'ter application of the repellent activity which
bee by the present invention been extended to
Ethyl cellulose
Cellulose, acetobutyrate ............. --..-..- 2.3
Propylene glycol monostearate .......... ..- 2.0
Dimethyl phthalate ................... .... 55.8
2-ethyl hexane-1,3-diol. ...... --.._..--....--.. 18.6
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