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Patented Jan. 7, 1947
Emil A‘. Vitalis, East Port Chesten'Conm, assignor‘
to American Cyanamid Company, ‘New York,
N. Y., a corporation of Maine I
I No Drawing. ‘Application December 14, 1943,
Serial No. 514,297
e Claims. (01. 106-13)
This invention relates to anti-fogging agents
for transparent surfaces such as glass or the
transparent resins such‘ as methyl methacry
late used in the Windshields of automobiles, air
planes, etc. and in optical instruments. A prin
cipal object of the invention is the provision of an
anti-fogging agent that is more permanent than
those that have previously been used, and which
will therefore maintain its effectiveness for long
er periods of time.
The invention will be de
as the only vprincipal‘anti-fogging agent a wet;
ting or surface-active agent together with awa
ter insoluble solvent therefor, the invention‘ also
includes compositions of this type‘ which also
contain a water-soluble adhesivev capable of pro
moting adhesion of the ?lm to the glass or other
transparent material, such adhesive being se
lected from the class consisting of water-soluble
starches and gums. For example, water-soluble
10 gums such as gum tragacanth, Irish moss and
scribed with particular reference to military uses,
but it should be understood that the advantages ‘ ‘
thereof are also important for other purposes
the like, may be employed. Likewise, citrus pec
tin, apple pectin and other similar water-soluble
adhesives may be used.
Further, water-soluble
or alkali solubilized corn starch and similar
and can be obtained whenever it is desired to
starches including wheat ‘staroh'may be em
maintain a transparent surface free from fog‘ or 15
condensed moisture under changing conditions
Although any wetting agent may be used in
of temperature or humidity.
conjunction with water~insoluble solvents to pro
duce anti-fogging compositions in "accordance
present time to maintain the line of sight) free
with the present invention I greatly prefer those
from fog on transparent solid surfaces of air 20 wetting agents which are soluble in hydrocarbons
planes. Thus, for example, during the ?ight of
of low vapor pressure, such as’ high boiling pe
An anti-fogging material is required'at ,the
a dive bomber from an altitude of about‘ 8,000
troleum hydrocarbons. The most effective agents
feet (temperature about 32° F.) to sea level, the
for this purpose of which I am aware are the sur
sudden change in temperature and relative hu
face-active esters of organic sulfopolycarboxylic
midity of the air results in a condensation of
acids‘such as the dibutyl, diamy1 and dihexyl es
moisture on the Windshield and also on the lenses
of the bomb-sight, and this seriously interferes
with the effectiveness of the attack. The prin
cipal loci of fog are on the surfaces of the avi
ters of sulfophthalic acid, the diamyl, dihexyl,
dioctyl and didecyl esters of sulfosuccinic acid
and the tributyl, triamyl and trihexyl esters of
sulfotricarbalyllicacid. These and similar sul~
ator’s goggles and on the external and internal 30 fonated compounds are preferably used in the
surfaces of the lenses in the telescope. An anti
form of their sodium, ammonium, or other wa-v
fogging agent must not only function during the
ter-soluble salts: Other oil-soluble wetting
dive, but it must also continue to function in
agents that may be used are sodium or ammonia
?ight and after the optical equipment has been
um alkyl aryl sulfonates (sold commercially as
stored on the ground, and the hot, humid atmos
“Nacconol”), alkylated aryl sulfonates (sold as
phere of the South Paci?c and other tropical
“Santomerse”) alkyl phenylene sodium sul
combat areas causes this problem to be particu
fonates (sold as “Invadine B”), the compound
C‘17H33CON-—CH3C2H4SO3N&, which is the stearyl
A successful anti-fogging agent must possess
amide of methyl taurine (sold as “Igepon T”)
surface-active properties; i. 6., it must contain an 40 and the sodium sulfonate of oleic acid ester of
organic hydrophobic radical together with a hy
aliphatic compound (sold as .“Igepon AP”). It
drophilic group that will cause it to take up the
should be mentioned, however, that many of
water droplets that condense as fog and thus
these wetting agents in their commercially avail
maintain a clear transparent ?lm. However, the
able iorms contain inorganic salts such as sodi
great majority of commercial wetting agents 45 um sulfate which should be removed before they
possess rather poor anti-fogging'properties be
are used for the purposes of the present inven
cause of their excessive water-solubility, which
causes them to be dissolved in the condensed
Any water-insoluble ‘high-boiling solvent for
moisture. In accordance with the present inven
the wetting agents may be employed. The sol-é.
tion the excessive water solubility of the most ef
vent or mixture of solvents may be high-boiling
fective surface-active agents is overcome by the
liquids at ordinary temperatures, such as di
addition of a water-immiscible solvent for the
methyl or di-butyl phthalates, or semi-solids
wetting agent which will function to reduce its
such as lecithin, but I greatly prefer to employ
solubility in water and thus to retain the wetting
agent in the ?lm formed on the glass or other 55 low vapor pressure hydrocarbon solvents such
as petroleum waxes and thelike. Thuskfor ex
surface to be protected against fogging.
In addition-to anti-fogging agents containing
ample, the petroleum ~jelly known commercially
as “Vaseline” produces excellent results and can
be used as a solvent for any of the wetting agents
A sample of the product was applied to glass
as a thin ?lm by means of a wet cloth.
listed above, and water-insoluble aliphatic hy
drocarbons of low vapor pressure therefore con
stitute the preferred solvent for use-in practic
ing the invention.
polishing with a dry cloth the ?lm was clear
and totally invisible, but the glass remained re
sistant to fogging even after it had been heated
in an oven at 100° F. and 90% relative humidity
for several hours.
Ordinarily it is not necessary to employ a
large quantity of the water-insoluble solvent,
Example 2
even as compared with the quantity of wetting
agent used. For most purposes about 5—25% of 10
A solution of 8 parts by weight of sodium
petroleum jelly or other water-insoluble solvent
dioctyl sulfosuccinate in 90 parts of water was
should be employed, based on the weight of the
prepared at 180° F. as described in Example 1
wetting agent. The quantity of wetting agent,
and cooled to 140° F. 2 parts of “Vaseline” were
in turn, is ordinarily only about 5 to 20% of
then melted, heated to 140° F. and added to the
the entire weight of the complete anti-fogging 15 wetting agent solution with strong agitation.
composition, from which it is apparent that only
The resulting dispersion was cooled and formed
very small quantities of the organic solvent need
a paste similar to the product of Example 1.
be employed. However, even these small quanti
It was found to possess excellent anti-fog proper
ties will produce a remarkable improvement in
ties when applied to glass. The ?lm retained its
the permanency of the composition as a whole. 20 anti-fogging properties even after the treated
From the foregoing description it is evident
glass had been heated in an oven at 100° F. and
that the essential ingredients of my improved
90% relative humidity for several hours.
anti-fogging composition are a wetting agent,
Example 3
which is preferably of the oil-soluble type, and
a high boiling water-insoluble solvent therefor.
A composition similar to that of Example 1
These may be applied as such or they may ?rst
but containing corn starch was prepared with
be converted into an aqueous paste by dissolving
the following composition, the parts being by
the wetting agent in water and emulsifying the
water-insoluble solvent in the aqueous solution.
It will be understood that in the latter case the 30 Sodium dioctylsulfosuccinate _____________
__ 3
water and any other volatile material is quickly
Pearl starch _____________________________ __ 4
evaporated from such pastes when they are ex
Ethylene glycol __________________________ __ 20
posed in thin ?lms, leaving the wetting agent and
Petroleum jelly __________________________ __
its solvent as a mutual solution of low water
solubility but having excellent anti-fogging prop
Water _____________________________ __ balance
The starch was boiled in the water for 1A» hour.
The wetting agent was dissolved in the ethylene
agent and the water-insoluble solvent therefor,
glycol and added to the hot starch-water solu
the ?nished composition may also contain about
tion which was then cooled to 140° F. The petro
1'-5% of its total weight in the form of a water 40 leum jelly was melted and added at this temper
soluble adhesive of the type described above.
ature with agitation, after which the product
Gum tragacanth is preferred for this ‘purpose,
was cooled to a thin ‘paste.
although any other water-soluble adhesive may
The composition possessed good permanency
be employed. In frigid climates the composition
and anti-fogging properties when tested as de
may also contain an anti-freeze such as glycerine, '
scribed in Examples 1 and 2.
ethylene glycol or other water-soluble compound
What I claim is:
capable of reducing the freezing point, as well as
1. An anti-fogging composition comprising a
small amounts of a preservative such as phenyl
surface-active ester of a sulfopolycarboxylic acid
mercuric acetate and a dyestu? if desired. Dyes,
together with 5—25% of a petroleum jelly, based
preservatives and anti-freezes are well known in- '
on the Weight of said ester.
gredients of anti-fogging compositions, and are
2. An anti-fogging composition comprising a
not claimed as a part of the present invention.
surface-active ester of an aliphatic sulfopoly
The invention will be illustrated in greater de
carboxylic acid together with 5-25% of a petro~
tail by the following speci?c examples. It should
leum jelly, based on the weight of said ester.
be understod, however, that although preferred
3. An anti-fogging composition comprising a
embodiments of the invention may be described
surface-active ester of sulfosuccinic acid together
in these examples they are given primarily for
with 5—25% of a petroleum jelly, ‘based on the
purposes of illustration and the invention in its
weight of said ester.
broader aspects is not limited thereto.
4. An anti-fogging composition comprising
5-20% by weight of a surface-active ester of a
Example I
sulfopolycarboxylic acid, 0.25-5% of a petroleum
A water solution of sodium dioctyl sulfosuccin-r
jelly, and 1—5% of a water-soluble adhesive selec
ate was prepared by adding 9.4 parts by weight of
ted from the class consisting of water-soluble
In addition to the wetting or surface-active
85% of sodium dioctyl sulfosuccinate to 86.6 parts
by weight of water heated to 180° F. and stirring
to complete solution. 2 parts by weight of gum
starches and gums.
5-20% by weight of a surface-active ester of an
traeacanth were dissolved in an equal weight of
aliphatic sulfopolycarboxylic acid, 0.25-5% of a
petroleum jelly, and 1—50% of a water-soluble
isopropanol and added to the water solution.
The latter was then cooled to about 140° F. with
continual stirring. 2 parts by weight of “Vas
6. An anti-fogging composition comprising
5-20% by weight of a surface-active ester of
sulfosuccinic acid, 0.25—5% of a petroleum jelly,
and 1-5% of' a water-soluble starch.
eline” were melted, heated to 140° F. and poured
into the solution with stirring. This resulted in
an extremely ?ne emulsion. Upon cooling the
product was obtained as a soft paste which could
he:readily;~ diluted with. water.
5. An anti-fogging composition comprising
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