US 3212909 A
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United States Patent 3,212,909 ANTIFOGGING COMPOSITION Arthur B. Leigh, 18 Georgia Ave., Lowell, Mass. No Drawing. Filed Oct. 7, 1960, Ser. No. 61,076 6 Claims. (Cl. 10613) This invention relates to an antifogging composition which when spread or rubbed on a smooth hard surface such as glass or metal will prevent or minimize the formation on the surface of a fog deposited from atmospheric moisture. The composition may be supplied in the form of a flexible porous carrier sheet of fibrous material impregnated with the composition.
There has for a long time existed a problem in preventing the formation of vision-obscuring films of fog or moisture droplets on such smooth surfaces as windows, mirrors, eyeglass lenses, automobile Windshields, etc.; and numerous proposals have been made for solving the problem including the application to the surface of compositions containing materials which are hydrophilic and/ or surface active in nature such as glycerine, surface active esters of sulfocarboxylic acids and the like. While such compositions are initially effective, they are deficient in durability, being rapidly removed or washed away from the surface to which they are applied. It has also been proposed to improve the durability of such compositions by including in them a hydrophobic material such as petroleum jelly, but such compositions have suffered from the disadvantage that they require extreme care during application to the surface in order to avoid smearing or streaking.
It has now been found that it is possible to provide an antifogging composition having great durability while at the same time completely eliminating any tendency to smear or streak during application of the material to the surface by employing a composition containing an ammonium soap in admixture with a surface active agent which is a sulfated or sulfonated fatty material. A humectant or hygroscopic material is preferably included as an additional ingredient in the composition. The ammonium soap ingredient is a water-soluble material, hence has no tendency to streak or smear when applied. It is believed that upon standing exposed to the atmosphere for a period of time in the form of a thin film, however, the ammonium soapingredient of the composition is hydrolyzed, with the loss of the volatile ammonia and formation of a water-insoluble free fatty acid. It is believed to be the formation of this fatty acid in situ on the surface which provides the remarkable durability of the compositions effect.
While a variety of sulfated or sulfonated fatty materials which are surface active agents are readily available and may be employed in the compositions of the present invention, it is preferred to employ fatty alcohol sulfates, in the form of their alkali metal salts, containing from 8 to 18 carbon atoms; sodium lauryl sulfate is the material of choice.
The ammonium soaps which have been found to be satisfactory include the ammonium salts of higher fatty acids having from 16 to 18 carbon atoms, of which ammonium palmitate and ammonium stearate are preferred.
Hygroscopic materials which have been found to be particularly advantageous as ingredients of the composition include glycerine and polyoxyethylene sorbitan monolaurate.
The relative proportions of the several ingredients of the composition may be varied over a wide range. Best 3,212,909 Patented Oct. 19, 1965 results are achieved with compositions in which the amount of ammonium soap ranges from 3% to 50% by weight of the sulfated or sulfonated fatty material. When a hygroscopic material is present, it may be present in any amount up to 50% by weight of the combined ammonium soap and sulfated 0r sulfonated fatty material.
It will be appreciated that it is also possible to incorporate in the composition minor quantities of such additives as perfumes, dyes, and the like without detracting from the eificacy of the composition.
The composition may be applied to the surface to be protected in the form of a solution in a volatile solvent such as water or a lower alcohol such as ethyl alcohol or isopropyl alcohol or a water-alcohol mixture, in which case the solvent merely serves to distribute the composition over the surface to which it is applied, then rapidly evaporates, leaving a thin film of the composition extending over the surface. When the composition is applied to the surface in the form of such a solution, the total solids content of the solution may vary from 5% to 25% by Weight or more. The composition may also be applied to the surface in the form of a paste or solid mix substantially free from solvent, in which case a flexible porous sheet of fibrous material is preferably employed as a carrier, the sheet being impregnated with the composition which is distributed throughout the sheet, and the impregnated dried sheet is rubbed on the surface to be treated.
A preferred form of the invention comprises a porous flexible paper sheet, e.g., a paper towel, impregnated with the composition. This impregnation is preferably carried out by immersing the fibrous carrier sheet in a concentrated solution of the composition in a volatile solvent such as water, a lower alcohol such as ethyl or isopropyl alcohol, or mixtures of water with such alcohols, followed by drying the sheet. The concentration of the solution employed to impregnate the paper may vary considerably; it preferably contains from 25% to or more total solids. The quantity of antifogging composition present in the fibrous carrier sheet after removal of the volatile solvent will vary a great deal, of course, depending upon the thickness and density or porosity of the fibrous sheet and can readily be adjusted by those skilled in the art to provide an adequate supply of the composition to cover any specified surface area.
The following specific examples are intended to illustrate more clearly the nature of the present invention without acting as a limitation upon its scope.
Example 1 The following composition was prepared, in which the parts are by weight:
Parts Sodium lauryl sulfate 20 Ammonium stearate 3 Glycerine 5 Ethanol solvent 72 The first three ingredients readily dissolved in the ethanol solvent to give a clear solution which could be applied to the surface of an automobile windshield or to a mirror either by spraying from an atomizer or by soaking a cloth or sponge in the solution then rubbing it across the surface. Upon drying, the composition was found to be highly effective in preventing formation of fog upon the surface under conditions of high humidity, and it was found to retain its effectiveness for a remarkably long period of time. Ammonium palmitate could be substituted for ammonium stearate with the same results.
Example 2 The following composition was prepared, in which the parts are by weight:
The first three ingredients readily dissolved in the solvent to form a clear solution. A sheet of thin, flexible, porous, absorptive paper was immersed in the solution, then allowed to dry. The impregnated paper sheet could then be employed for rubbing the surface of Windshields, windows, mirrors, eyeglass lenses, and even a variety of metal surfaces, in order to deposit upon the surface a thin, invisible film of the composition free from smears and streaks. The film was found to be highly effective in preventing the formation of water droplets or fog upon the surface and retained its effectiveness for a long period of time. Similar results may be obtained by substituting other sulfated or sulfonated fatty materials for the sodium lauryl sulfate as well as by substituting ammonium palmitate for the ammonium stearate. Excellent results may also be obtained by incorporating 5 parts by weight of polyoxyethylene sorbitan monolaurate in the composition either in place of the glycerine or in addition thereto.
Although specific embodiments of the invention have been described herein, it is not intended to limit the invention solely thereto, but to include all of the obvious variations and modifications within the spirit and scope of the appended claims.
What is claimed is:
1. A device for applying antifogging composition to a smooth surface consisting essentially of a flexible porous sheet of fibrous material impregnated with a composition consisting essentially of a member of the class consisting of surface active sulfated and sulfonated fatty materials in admixture with an ammonium soap of a fatty acid having from 16 to 18 carbon atoms, the amount ofsaid soap ranging from 3% to by weight of said fatty materials.
2. A device as claimed in claim 1 in which said sheet consists essentially of paper.
3. A device for applying antifogging composition to a smooth surface consisting essentially of a flexible porous paper sheet impregnated with a composition consisting essentially of sodium lauryl sulfate and ammonium stearate, the amount of ammonium stearate ranging from 3% to 50% by weight of said sulfate.
4. A device for applying antifogging composition to a smooth surface consisting essentially of a flexible porous paper sheet impregnated with a composition consisting essentially of sodium lauryl sulfate and ammonium palmitate, the amount of ammonium palmitate ranging from 3% to 50% by weight of said sulfate.
5. A device for applying antifogging composition to a smooth surface consisting essentially of a flexible porous paper sheet impregnated with a composition consisting essentially of sodium lauryl sulfate, ammonium stearate, and glycerine, the amount of said stearate ranging from 3% to 50% by weight of said sulfate and said glycerine being present in an amount up to 50% by weight of the combined weight of said stearate and said sulfate.
6. A device for applying antifogging composition to a smooth surface consisting essentially of a flexible porous paper sheet impregnated with a composition consisting essentially of sodium lauryl sulfate, ammonium stearate, and polyoxyethylene sorbitan monolaurate, the amount of said stearate ranging from 3% to 50% by weight of said sulfate and said monolaurate being present in an amount up to 50% by weight of the combined weight of said stearate and said sulfate.
References Cited by the Examiner UNITED STATES PATENTS 1,123,367 1/15 Pickering 10613 2,365,297 12/44 Schweizer l0613 FOREIGN PATENTS 784,228 10/57 Great Britain.
ALEXANDER H. BRODMERKEL, Primary Examiner.
JOSEPH REBOLD, MORRIS LIEBMAN, Examiners.