2,414,074 Patented Jan. 7, 1947 UNITED (‘STATES ‘ PATIENT orncs ANTIFOGGING COMPOSITION 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) . 1 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 2 ' , 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 ployed. 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 25 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 35 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 larly severe. ‘ ' ‘ ‘ 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 tion. 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. 50 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 2,414,074 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. a . Upon 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 weight: water-insoluble solvent in the aqueous solution. Percent 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 erties. 35 2 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 starch. 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 75 ENHL A. VITALIS'.