US 3711409 A
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United States Patent 3,711,409 ICE-PREVENTIVE AND DEICING OIL-liN-WATER EMULSION Douglas John Ayres, 102 Goidhurst Terrace, London NW. 6, England, and Derek Greenwood, London, England; said Greenwood assignor to said Ayres No Drawing. Continuation-impart of abandoned application Ser. No. 439,469, Mar. 12, 1965. This application Nov. 23, 1970, Ser. No. 92,184
Int. Cl. (109k 3/18 US. Cl. 252-70 29 (Ilaims ABSTRACT OF THE DISCLOSURE An ice-preventive and deicing material for application to metallic objects, such as railway switches and the like, which is in the form of a viscous, stable, oil-in-water emulsion, comprising, about 5% to 30% of the lubricant oil or grease, which is substantially insoluble in water, as the dis perse phase; about 2 to 20% of a cationic or non-ionic surface active agent as an emulsifying agent; and the balance an aqueous solution, as the continuous phase, containing about 2 to 5% of the total composition of a water-absorbing, viscosity-maintaining compound and a sufficient amount of a freezing point depressant for water to lower the freezing point of the water with which the composition comes into contact and thereby prevent the formation of ice on the protected object or remove ice from the protected object, provide lubrication of parts where required and prevent adhesion of parts as needed.
CROSS-REFERENCES TO RELATED APPLICATIONS The present application is a continuation-in-part of application Ser. No. 439,469, filed by the present inventors on Mar. 12, 1965, and entitled De-Icing Materials, now abandoned.
BACKGROUND OF THE INVENTION The present invention relates to an ice-preventive and deicing material for metal objects. In a more specific aspect, the present invention relates to an ice-preventive and deicing lubricant for application to metal objects which also serves as a lubricant and corrosion preventive.
DESCRIPTION OF THE PRIOR ART Heretofore, a large number of materials have been utilized for the removal of ice from metal objects, such as railway switches, railway tracks, overhead conductor wires for trolleys, aircraft parts and the like. Likewise, various compositions have also been proposed for the prevention of ice formation on such metal objects. However, these techniques and compositions have numerous disadvantages which are briefly referred to in the following discussion of the prior art. It has been the general practice over a number of years to free frozen railway points and switches and the like by means of a water-soluble material which lowers the freezing point of water and solute to below ambient temperature. Equal amounts of such mate rials lower the freezing point of an aqueous solution in inverse proportion to the molecular weight of the material used.. As a matter of economics, the cheapest material available should be used and should have as low a molecular weight as possible. The most common material used for this purpose has been sodium chloride in the form of dendritic salt, but other cheap materials such as urea and calcium chloride have also been tried. The disadvantage of these materials is that once the ice has melted, the solution runs off the protected part, carrying the salt with it. Any salt remaining is then wiped off by subsequent movement of the point over the slide plate so that freezing can again 3,711,409 Patented Jan. 16, 1973 occur in an hour or so as water condenses from the atmosphere or water is deposited on the point or slide plate from freezing fog, snow or rain. As a result, such materials have a maximum effectiveness of about 4 hours. Further, many metal objects, such as switches and the like are normally lubricated in order to maintain them in effective operation and to prevent corrosion. Salt solutions and the like have varying degrees of incompatibility with such lubricants and the oil or grease is scraped off by the crystallizing ice as the points are moved and a similar removal of the lubricant occurs as the points are unfrozen, either by deicing salt or by a rise in the ambient temperature. The removal of the lubricant coating and the corrosive effect of these cheap compounds generally leads to substantial corrosion of the surface of the previously polished sliding parts of the point or the switch with a consequent difiiculty in moving the parts by the signalman.
Another and better approach, which is based upon prevention of ice formation, has been the use of special oils and greases which remain flowable at low temperatures and which contain alcohol. In these compositions, the alcohol migrates from the oil to the: surface and mixes with water, condensing on the surface, thereby lowering its freezing point. These materials are not very effective in use, since there is a substantial loss of alcohol to the atmosphere during storage and after application to the metal objects. The other disadvantages of these materials are essentially the same as water-soluble salts and the like in that they are incompatible with normal lubricants and they are readily washed away or flow away from the protected surface.
Another proposed material is an anti-icing fluid described in US. Pat. 2,948,625, which is particularly useful for aircraft parts. This material comprises a delicately balanced water-in-oil emulsion in which the continuous phase consists of a long chain fatty acid ester or a partial ester (specifically sorbitan sesquioleate) dissolved in a white mineral oil and the disperse phase consists of a deicing fluid, namely, an aqueous solution of lithium chloride, as a freezing point depressant, with small quantities of carboxymethylcellulose for increasing the viscosity, an amide oxide for inhibiting vapor phase corrosion of copper and an alkyl quaternary ammonium salt as a corrosion inhibitor for aluminum. This anti-icing fluid is described as functionally dependent on the instability of the oil film which normally surrounds the deicing fluids; that is, the oil film frequently becomes discontinuous and allows the deicing fluid to contact any ice film. The ice is then melted by lowering the freezing point and the mixture of melted ice and deicing fluid maintains a liquid layer between the aircraft surface and the ice coating. It is said that the ice coating can then be easily lifted or brushed from the surface. From this description of the manner in which this particular material functions, it is quite obvious that the effectiveness of the material is short-lived in that the deicing fluid will generally be spent after a single coating of ice develops. In addition, this composition has the disadvantage that it provides no lubrication.
SUMMARY OF THE INVENTION The present invention relates to an ice-preventive and deicing material for use on metallic objects adapted to adhere to such objects, even when vertically disposed, and provide lubrication where necessary; comprising, an oil-inwater emulsion consisting essentially of a minor proportion of an oil or grease, as the disperse phase; a cationic or non-ionic emulsifying agent; and a major proportion of an aqueous solution, as the continuous phase, including an amount of a water-absorbent, viscosity-maintaining compound sufiicient to absorb water from melted ice or deposited from the atmosphere without substantially changing the viscosity of the overall composition and a freezing point depressant for water in an amount sufiicient to reduce the freezing point of the composition below the lowest anticipated ambient temperature.
Numerous advantages are attributable to the novel composition of this invention. The high viscosity of the material provides lubrication for moving metal parts and maintains adhesion to both vertical and horizontal surfaces of the protected object. The viscosity is substantially independent of the temperature. The composition exhibits good visco-elastic regain. The composition adheres Well to all metals. The composition has a low freezing point and therefore acts as an ice-preventive or antifreezing agent. The composition has a good deicing effect, thereby readily removing ice from frozen objects. The composition is easy to apply to the protected object. The protected object is protected by the anti-corrosion properties of the composition. The composition has a high degree of persistence due to the fact that it maintains its viscosity without substantial change while taking up water condensing from freezing fog, snow, ice or rain and thereby performs its function for at least several days and, in most cases, for longer periods of time. The material may be stored over periods of several years without deterioration and is non-flammable. The composition is also compatible with conventional lubricants which are normally utilized for sliding metal surfaces during periods of non-freezing weather.
DESCRIPTION OF THE PREFERRED EMBODIMENTS While the composition of the present invention is particularly useful for the prevention of ice formation and the removal of ice from railway switches, particularly the contact points and slide plates thereof, numerous other uses will be apparent to those skilled in the art. For example, the material may be utilized on overhead conductor wires of trolleys or railways, on both non-conductive and conductive tracks of trolleys and railways, on aircraft parts, on machinery used in the cosmetic and food processing industries where refrigerated conditions exist, etc. The type of use to some extent dictates the nature of the composition and the amounts of ingredients to be employed. [For example, for railway switches, tracks and the like, a heavy paste or grease is most advantageous. On the other hand, where trolley wires and the like are to be treated, a thinner, more fiowable material may be utilized. Further, the material should be noncorrosive to copper and copper alloys when it is utilized on conductor wires. It should also be a conductive composition when utilized on overhead conductor wires and on conductive tracks. When utilized for the protection of aircraft parts and the like, the composition should be noncorrosive to aluminum alloys. In most uses, however, the material should be non-corrosive to ferrous metals and alloys. When used on aircraft parts, the composition should be non-deleterious to rubber or rubber components, since rubber components are often associated with the metallic parts. Similarly, it has become a practice to substitute concrete railway ties for conventional wooden ties. Under these circumstances, a rubber pad or cork-filled rubber pad is utilized between the rails and the concrete ties. In these instances, the composition should be non-deleterious to rubber also. Where the composition is to be used in the cosmetic and food industries, the composition should not be harmful, and all ingredients thereof should be acceptable as food or cosmetic components. As will be apparent from the following detailed discussion, suitable ingredients will be apparent to one skilled in the art any may be selected on the basis of their properties from the manufacturers specifications or as set forth in standard textbooks and the like.
-As previously indicated, the composition of the present invention is in the form of a stable, oil-in-water emulsion, containing an aqueous continuous phase, including water, a water-absorbing, viscosity-maintaining compound and a freezing point depressant for the water; a non-ionic or cationic surface active agent as an emulsifier and a substantially water-insoluble lubricating oil or grease as the disperse phase. The composition may also contain a humectant and a compound having visco-elastic or thixotropic properties.
While it is not intended that the present invention shall be limited by any theory of operation, it is believed that the composition of the present invention accomplishes its objectives in the manner indicated below. When the material is applied to the metallic surface to be protected, before freezing conditions begin, any precipitation of water due to snow, fog, or sleet, either as flakes of ice or as freezing condensate, is absorbed by the water-absorbing, viscosity-maintaining material, thereby causing only a slight dilution of the continuous phase of the emulsion but reducing the viscosity of the emulsion by only an insignificant amount. Thus, the emulsion remains effective over a period of several days. At the same time, the freezing point depressant in the continuous phase of the emulsion lowers the freezing point of the emulsion to a point below the freezing point of water and below the anticipated ambient temperature, thereby preventing the formation of snow or ice and preventing the emulsion itself from freezing. Similarly, when the material is applied to an ice-coated metal surface, the freezing point depressant in the continuous phase immediately comes into contact with the ice, melts it, absorbs it, and is thereby slightly diluted while at the same time losing little of its initial viscosity. Since the emulsion thus remains stable and is retained on the protected object, the freezing point depressant material prevents the formation of any frozen water layer from coming into contact with the metal surface over the range of temperatures anticipated. The non-ionic or cationic emulsifying agent not only forms the emulsion, but also improves the adhesion of the oil or grease to the metal surface and spreads it over the metal surface. Anionic emulsifying agents are to be avoided since they prevent adhesion of the grease or oil to the metal surface and act as a detergent to wash away the composition when diluted by water from ice or the atmosphere. The freezing point depressant is also preferably one which is non-corrosive to the particular metal being treated and, as previously indicated, it prevents ice from forming, prevents freezing of the composition itself, melts any ice which may be present and acts as a corrosion inhibitor. The visco-elastic or thixotropic material serves to improve the adhesion of the composition to sliding metal surfaces and improve the spreading ability of the material during movement. Even when the composition is scraped from the surface, it will readily flow back due to its thixotropic and elastic properties. The humectant prevents drying out of the material during storage.
The disperse phase of the composition of the present invention includes any of the conventional natural or synthetic lubricating oils or greases which are substantially water-insoluble and therefore are capable of forming a stable, oil-in-water emulsion with the aqueous phase of the composition. The consistency of the oil or grease will, of course, depend upon the use to which the composition is to be put. In some instances, a relatively non-viscous fiowable oil may be used, while in other instances, a grease of greater consistency or viscosity may be employed. In the latter instance, the grease may be of a natural grease consistency, such as certain of the higher molecular weight synthetic lubricants, or it may be a naturally low viscos- 'ity mineral or synthetic oil or the like, which has been thickened with a conventional gelling agent utilized in the production of lubricating greases. The properties and characteristics of such oils and greases are well known to those skilled in the art and more specific details may be obtained from standard texts, such as the Chemistry of Petroleum Derivatives by Ellis, The Chemical Catalog Company, Inc., 1934, which covers appropriate mineral base oils and greases and Synthetic Lubricants by Gunderson and Hart, Reinhold, 1962, which covers a wide variety of synthetic lubricants. The disperse phase, of course, contributes to the lubricating function where relatively moving parts are to be protected, it should also spread well and adhere to the major portion of the item to be protected and it should be non-corrosive to the metals to which it is applied or with which it comes into contact. For example, where railway rails, switches or the like are to be protected, the oil or grease should be non-corrosive to ferrous metals or alloys of ferrous metals. Where conductive cables are to be protected, the material should be noncorrosive to copper and copper alloys and should also have good conducting properties of its own. Where aircraft parts and the like are to be protected, the material should be non-corrosive to aluminum. Also, as previously indicated, the grease or oil should be compatible with greases or oils used as lubricants during normal non-freezing atmospheric conditions. Further, where the material comes into contact with rubber components, the grease or oil should be selected on the basis of being nondeleterious to rubber components. For example, where rubber components are not present and a wide variety of metallic surfaces are to be protected, the grease or oil may be any mineral grease or oil. A particularly suitable material because of its availability, economy, and good low-temperature characteristics (as indicated by its low pour point) is a naphthenic mineral oil, normally utilized in the lubricating art.
Where the composition will come into contact with rubber components, mineral oils will normally be deleterious to the rubber components. Consequently, a synthetic lubricant which is non-deleterious to rubber should be used. For example, polyglycols, originally known as Ucon fluids and marketed by Union Carbide Company, may be utilized. Such polyglycols have the following structural where the Rs are hydrogen or alkyl. These materials have also been variously referred to as glycols, polyethers, polyalkylene glycols, and polyoxyalkylene glycols. Included within this class are a number of materials. In any event, however, the class in general has little effect on rubbers or metals. Specific examples include diols, such as polypropylene glycol, monoethylene glycol, and mixed oxyethylene-oxypropylene glycols; monoethers, such as methyl ether of propylene glycol; butyl ether of mixed oxyethylene-oxypropylene glycol; acyl ether of mixed oxyethylene-oxypropylene glycols; and diethers, such as ethyl ether of butoxy-polypropylene glycol. Generally, polyglycols derived from compounds whose molecular weights are equivalent to propylene or higher are particularly preferred since these materials are substantially water-insoluble and therefore will form an appropriate oil-in-water emulsion; whereas, polyethylene glycols and like polyglycols having substantial percentages of ethylene oxide will absorbsome water from the atmosphere and are to some extent soluble in water. As indicated previously, these materials are substantially non-corrosive to all metals. Materials which are substantially insoluble in water, are non-corrosive to most metals and are non-deleterious to rubber are the so-called silicon oils and greases having the following general formula:
R R R R-SiO- --S iO Si-R The most common of these are the methyland phenylsubstituted materials having short polymer lengths and little or no cross-linking. These materials also have an advantage of having a low freezing point in and of themselves. Suitable related materials are the organic substituted siloxanes, such as hexa(methoxy)disiloxanes; 1,3- di(tert.-butoxy) l,1,3,3-tetra(2-ethylbutoxy)disiloxanes and the like. Yet another group of synthetic materials which are insoluble in Water include fluorocarbons. Among these are acyclic fluorocarbons, such as methforane, n-dodecforane, etc., and cyclic fluorocarbons, such as benzforol; Z-methylforyl; cyclohexforane; naphthalforine; etc.
Related materials such as chlorofiuorocarbons are also substantially insoluble in water, readily wet metal surfaces and are essentially non-corrosive. Such materials include chlorotrifluoroethylene polymers, chlorofluorocarbon polymers, perhalogenated compounds and the like. Where rubber components are not present, other synthetic materials, essentially insoluble in water, are the dibasic acid esters obtained by reacting a straight chain dibasic acid, such as adipic, azelaic or sebacic acid with primary branched alcohols, such as ethyl hexanol and having the following general formula:
Specific materials include di(n-octyl-a,a,a',ix-tetraethylazelate; di(2,2-dimethylamyl-tx,em,m'-tetraethyl)azelate; etc. The most desirable materials of this character are sterically hindered in their di-acid portion. As previously pointed out, numerous other synthetic, as well as natural oils and greases, may be utilized, depending upon the environment in which they are to be utilized and these materials may be selected in accordance with manufacturers specifications or standard textbooks on the subject. Where the composition may contain solid particle-form materials, suspensions of solid lubricating materials may also be included, such as polytetrafluorethylene, graphite or molybdenum disulfide, which can be in a colloidal form. Such colloidal materials will allow the solid material to be deposited on the metal surface after all the other components of the composition may have disappeared.
It is highly advantageous, particularly where the metal object to be protected comes in contact with foods or cosmetics, to utilize animal or vegetable oils. Such oils are often collectively referred to as fixed oils. They, of course, differ from mineral oils in containing oxygen. More particularly, the fixed oils contain glycerides, specifically, olein, palmitin, triricinollein and stearin. While some fixed oils are termed drying oils (due to oxidation), for example, linseed oil, the tendency of such oils to oxidize is inhibited by the fact that it is present in an emulsion form. The fixed oils may be in the form of blown oils, which, of course, have been treated to increase their viscosity. Suitable vegetable oils, include, olive, castor, rape, palm, coconut, cottonseed and sunflower oils. Rape oil is particularly useful because of its good lubricating properties. Coconut and palm oils are preferred for use in the cosmetic and food industries since they can be obtained in technically pure form and meet food hygiene requirements. Suitable animal oils, include, tallow, lard, sperm and fish oils. The use of vegetable and animal oils as lubricants for light and heavy machinery, particularly in the railway industry, is discussed in Lubrication and Lubricants, by Archbutt and Deeley, C. Griffin and Co., London, England. One disadvantage of animal and vegetable oils, when used alone is their high freezing points, for example:
C. Castor oil 10 to l8 Lard oil 4 to 5.5 Rape oil 2 to 12 Sperm oil About 0 However, one or more of these materials in the disperse phase of the present emulsion results in attainment of the several advantages of both phases in a manner not previously possible.
The disperse phase of the composition of the present invention preferably comprises about to 30% by weight of the total composition.
The surface active agent or emulsifying agent to be used in accordance with the present invention includes a cationic or non-ionic surface active agent. Cationic surface active agents include the secondary, tertiary or quaternary ammonium compounds. Suitable examples are; benzalkonium chloride, cetalkonium chloride, octodecyldimethylbenzyl ammonium chloride, hexamethonium chloride, alkyl trimethyl ammonium chlorides, lauryl pyridinum chloride, etc. Similarly, alkyl propylene diamine dioleates or other aliphatic amines derived from fatty acids may be utilized. Nonionic surface active agents suitable for use in accordance with the present in vention are exemplified by materials having an oxygenated side chain, such as, ethylene oxide condensates and ethylene glycol esters, polyoxyethylene plus a fatty acid, alcohol, amide or amine component, etc. Specific examples include diethyleneglycol monostearate, polyethylene tert.- dodecylthioether and related compounds, etc. As was indicated above, the cationic or non-ionic surface active agent not only acts as an emulsifying agent, but aids in spreading the disperse phase on the metallic surface and causes the same to adhere to metallic surfaces. Suitable cationic and non-ionic surface active agents are well known to those skilled in the art and are defined in any standard dictionary, such as the Condensed Chemical Dictionary 6th Edition by Reinhold, 1956. Such surface active agents are preferably present in amounts of about 2 to 20% by weight of the total composition.
The continuous phase of the oil-in-water emulsion is made up of an aqueous solution. This component comprises the remaining portion of the overall composition. Included within the aqueous phase are the water-absorbing, viscosity-maintaining compound and the freezing point depressant.
Where iron or steel is to be treated, the freezing point depressant is preferably a salt which is non-corrosive and corrosion inhibiting. Preferably, on the basis of economy, it should have a low molecular weight. One example is sodium nitrite. Suitable amounts of nitrite are about 10 to 48% of the composition. The effectiveness of sodium nitrite in lowering the freezing point is comparable with that of common salt and urea and it is also an excellent corrosion-inhibitor. The freezing point depressant may also be urea alone, mixtures of sodium nitrite and urea, and mixtures of sodium nitrite or urea with sodium chloride. The urea may also be combined with a corrosion inhibitor such as sodium benzoate. It is also possible to use sugar residues obtained from the production of edible sugars. Glycerol, ethyl alcohol and monoethylene glycol are also suitable freezing point depressants. For metals other than iron or steel, such as, aluminum, copper, and zinc, such salts should be avoided as freezing point depressants. However, some water-soluble salts may be used as corrosion inhibitors if ethyl alcohol or, preferably, glycerol is used as the freezing point depressant. Other freezing point depressants for aqueous solutions can be selected from any standard handbook, such as the Handbook of Chemistry and Physics, Chemical Rubber Publishing Company. Such standard listings also specify the concentration necessary to lower the freezing point a given amount. By way of illustration, however, the freezing point depressant may be present in amounts of about 10 to 60% by Weight of the total composition and, preferably, between about 2 to 10% by weight of the total composition.
While, as indicated previously, the freezing point depressant also serves as a corrosion inhibitor in many instances and some corrosion inhibition appears to be derived from cationic emulsifiers, it is often desirable to add a corrosion inhibitor. For example, where monoethylene glycol is. used a a freezing point depressant,
triethanolamine phosphate may be used as a corrosion inhibitor. Derivatives of glycine (aminoacetic acid), particularly derivatives of sacrosine (N-methyl amminoacetic acid) have numerous advantages as corrosion inhibitors. Glycine derivatives are innocuous and may be used in the cosmetic and food industries. Further, while certain glycine derivatives are particularly effective for protection certain specific metals, these materials are effective for most metals by virtue of their tendency to displace water from metal surfaces and protect the metal by their plating out effect. By way of example, acyl sarcosines, such as, sodium lauroyl sarcosinate (sold as Sarkosyl NL by The Geigy Co. Ltd.) is particularly protective to iron and aluminum, while oleoyl sarcosinate (sold as Sarkosyl O by The Geigy Co. Ltd.) gives superior protection to zinc and iron. The sarcosine derivatives also appear to have their corrosion inhibiting effect enhanced by the cationic surface active agents of the present composition. Alternatively, compositions of the present invention, which contain non-ionic surface active agents, are substantially improved in their adhesion qualities by the addition of sarcosine derivatives. For non-food applications, sarcosine (in its acid form) may be used with a tertiary amine base, such as, heptadecenyl imidazoline (sold as Amine O by Geigy Chemical Corp.). Where the metal object is copper, at chelating agent, such as, benzotriazole is favored. In addition to protecting copper, this material inhibits the corrosion of other metals affected by the presence of copper. Finally, this inhibitor reduces the rate of oxidation of organic solvents, such as, glycol and the rate of softening of rubber parts. The corrosion inhibitor may be added in amounts recommended for use in conventional lubricants or anti-freeze solutions. Typically, the amount should be about 0.25 to 2% by Weight of the total composition.
Any one of a variety of water-absorbing, viscositymaintaining compounds may be used in the present composition. This material swells to absorb water from the melted ice, if the composition is used to remove ice, or from the atmosphere, where the composition is used as an ice-preventive composition, while at the same time maintaining the viscosity of the material. Accordingly, the water-absorbing, viscosity-maintaining compound resists demulsification of the composition and helps to maintain the composition on metal surfaces due to suction or capillary tension forces. An excellent material for this purpose is sodium carboxymethyl cellulose. In addition to the sodium carboxymethyl cellulose, materials such as sodium alginate, hydroxyethyl cellulose, gelatin, or compounds of similar protein or cellulosic structure, or starch and its derivatives may be used. Where solid materials can be tolerated in the composition, clay mineral substances, such as sodium montmorillonite, and bentonite derivatives, such as bentones, halloysite, activated silica and the like, may be utilized. Suitable amounts of waterabsorbing, viscosity-maintaining compounds, include, about 0.5 to 20% by weight of the total composition and preferably between 1 and 12%. Still more specifications, 25% by weight is considered optimum.
In order to prevent the composition from drying out during storage, a humectant, such as, sorbitol, glycerol, etc., can also be added. This material will generally be added in amounts of about 5 to 10% by weight of the total composition.
In order to aid in spreading the composition on the object to be protected and to aid in the retention thereof on such object, it is also desirable to add to the composition a material having visco-elastic or thixotropic properties. Materials of this character include low molecular weight polyethylenes, polyisobutylenc, polyethylene glycol, glycerol, hydrogenated castor oil, sugars and the like. The previously mentioned clay minerals may also be utilized for this purpose.
Various specific examples of ice-preventive and de-icing materials according to the invention will now be described in more detail. These materials have been developed for use in freeing frozen railway poinfls and switches but may also be used for treating other mechanical equipment or parts of equipment exposed to cold conditions.
EXAMPLE 1 A cationic oil-in-water emulsion is prepared having the following composition by weight. The first column of figures shows the preferred proportions of the constituents and the second column the limits between which they may be varied:
The composition of Example 1 may be altered by replacing the sodium nitrite solution with a solution of urea including a corrosion inhibitor such as sodium nitrite OI benzoate, as follows:
Percent Preferred proportions Limits 40% w./w. urea solution in water 62 50-80 Sodium nitrite or sodium benzoate 5 (21-40 EXAMPLE 3 In a further alternative, the composition of Example 1 may be altered by replacing the sodium nitrite with a mixture of sodium chloride and sodium nitrite, as follows:
40% w./w. chloride/nitrite mixture solution: Percent Preferred proportions 67 Limits 50-80 The proportions of chloride to nitrite in the mixture may vary between 90:10 and 50:50.
In place of the sodium chloride in Example 3, one may use sugar residues obtained from the production of edible sugars.
To any of the above compositions, between 1 and of olyisobutylene may be added in the disperse phase to give viscoelastic or thixotropic properties to the emulsion. Alternatively, or in addition, a similar proportion of a material with a complex molecule such as polyethylene glycol, glycerol or sugar residues may be added to the continuous phase for this purpose.
To enable the viscosity of the emulsion to be better controlled, between 1 and 10% of cetyl alcohol may also be added to the disperse phase.
In place of the alkyl trimethyl ammonium chloride, other cationic materials may be used, such as an alkyl propylene diamine dioleate or other aliphatic amine derived from fatty acids.
10 EXAMPLE 4 Where a non-ionic emulsion is to be preferred, a composition such as the following may be employed:
Percent 40% w./w. sodium nitrite solution in water 68 Sodium carboxy methyl cellulose 2 Sorbitol 5 Cup Grease 15 Polyisobutylene 5 Diethylene glycol monostearate 5 EXAMPLE 5 Additional typical formulations are set forth below:
Percent by weight Freezing Point depressant l A-19 B-37 0-27 D-30 E-19 Water 8 29. 5 39 36 47 Sodium carboxy methyl cellulo 3 2. 5 3 3 3 A=sodium nitrite; I3=glycerol; C=ethyl alcohol; D=rnonethylene glycol; E=Urea.
In any of the above examples, the concentration of the freezing point depressant solution may be varied between 10% and 60% w./w.
'I he viscous and adhesive components of the emulsions described give them a consistency which makes them easy to apply and keeps them in position after application for at least the period between consecutive visits each day by the man responsible for maintenance of the point or switch, i.e., for a period of 18 hours or more.
The deicing materials can be stored for long periods at sites subject to all the extremes of ambient outdoor temperatures.
The consistency of the material can be varied from that of a liquid to that of a paste, for spray, brush or nozzle application, by varying the content of sodium carboxymethyl cellulose or similar compound and the quantity and particle size (if any) of the grease or oil. In some circumstances, it is desirable to give the material such a consistency that it can be agitated by introducing a turbulent stream of air bubbles to form an additional disperse phase, so as to produce a low density foamed mass of high cohesion which can. be placed on a snow layer covering the point.
Foam generation and properties may be improved by incorporating further surface active agents or proteins or saponin. Such a foamed material will rest as a coating on the snow by reason of its low density and has high cohesion by reason of the cellulosic, starch, and protein compounds mentioned, to resist rupture of the coating and to release freezing point depressant slowly.
What is claimed is:
1. An ice-preventive and deicing material in the form of a viscous, stable, oil-in-water emulsion consisting essentially of: 5 to 30% of a mineral oil, as the disperse phase; 2 to 20% of an emulsifying agent selected from the group consisting of cationic and non-ionic surface active agents; and the balance of an aqueous solution, as the continuous phase, containing 2 to 5% of the total composition of a water-absorbing, viscosity-maintaining compound and a sufficient amount of a freezing point depressant to lower the freezing point of water with which the composition comes in contact and thereby prevent formation of ice thereon and melt ice from objects to which the composition is applied.
2. An ice-preventive and deicing material according to claim 1, wherein the aqueous phase also contains 5 to 10% of sorbitol as a humectant.
3. An ice-preventive and deicing material according to claim 1, wherein the freezing point depressant is selected 1 1 from the group consisting of sodium nitrite, urea, mixtures of sodium nitrite and urea and mixtures of sodium nitrite or urea with sodium chloride.
4. An. ice-preventive and deicing material according to claim 1, wherein the oil is a naphthenic mineral oil.
5. An ice-preventive and deicing material according to claim 1, wherein the non-ionic emulsifying agent is diethylene glycol monostearate.
6. An ice-preventive and deicing material according to claim 1, wherein the cationic emulsifying agent is selected from the group consisting of alkyl trimethyl ammonium chloride and alkyl propylene diamine dioleates.
7. An ice-preventive and deicing material according to claim 1, and containing also 1 to 10% of a compound selected from the group consisting of polyiso butylene, polyethylene glycol, glycerol and hydrogenated castor oil, for imparting visco-elastic and thixotropic properties to the emulsion.
8. An ice-preventive and deicing material according to claim 1, wherein the water-absorbing, viscosity-maintaining compound is sodium carboxymethyl cellulose.
9. An ice-preventive and deicing material according to claim 1, wherein the material is in the form of a foam containing a mass of air bubbles constituting an additional disperse phase of the emulsion.
10. An ice-preventive and deicing material according to claim 1, wherein the emulsion, which has the consistency of a paste, consists essentially, by weight of 50 to 80% of an aqueous solution of an anti-corrosion, freezing point depressant selected from the group consisting of sodium nitrite, urea, mixtures thereof, and mixtures thereof with sodium chloride; 2 to 5% of carboxymethyl cellulose as the water-absorbing, viscosity-maintaining compound; 5 to of sorbitol; 5 to 30% of mineral oil, and 2 to of an emulsifying agent selected from the group consisting of diethylene glycol monostearate, alkyl trimethyl ammonium chloride and alkyl propylene diamine dioleate.
11. An ice-preventive and deicing material in the form of a stable oil-in-water emulsion, consisting essentially of: a minor proportion of a substantially water-insoluble lubricant capable of forming a stable oil-in-water emulsion selected from the group consisting of a mineral oil, a synthetic oil, a fixed oil, a grease of a mineral oil, a grease of a synthetic oil, a grease of a fixed oil, and mixtures thereof, in an amount sufiicient to spread over and adhere to the object being treated with the emulsion, as the disperse phase; an emulsifying agent selected from the group consisting of cationic and non-ionic surface active agents in an amount sufficient to form a stable oilin-water emulsion; and a major proportion of an aqueous solution, as the continuous phase, containing a waterabsorbing, viscosity-maintaining compound in an amount sufiicient to absorb environmental water with which said emulsion comes into contact during use without significantly altering the viscosity of said emulsion and a freezing point depressant in an amount sufiicient to lower the freezing point of said environmental Water with which said emulsion comes into contact during use and thereby prevent the formation of ice on and melt ice from said object being treated.
12. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a mineral oil.
13. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a material non-deleterious to rubber.
14. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a synthetic oil.
15. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a fixed oil.
16. An ice-preventive and deicing material in accordance with claim 14 wherein the fixed oil is a vegetable oil.
17. An ice-preventive and deicing material in accordance with claim 14 wherein the fixed oil is an animal oil.
18. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a grease.
19. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a silicone material.
20. An ice-preventive and deicing material in accordance with claim 11 wherein the lubricant is a polyglycol material.
21. An ice-preventive and deicing material in accord ance with claim 11 wherein the aqueous phase contains a corrosion inhibitor.
22. An ice-preventive and deicing material in accordance with claim 11 wherein the corrosion inhibitor is a derivative of glycine.
23. An ice-preventive and deicing material in accordance with claim 11 wherein the cationic surface active agent is selected from the group consisting of secondary, tertiary and quaternary ammonium compounds and aliphatic amines derived from fatty acids.
24. An ice-preventive and deicing material in accordance with claim 11 wherein the non-ionic surface active agent is a compound having an oxygenated side chain.
25. An ice-preventive and deicing material in accordance with claim 11 wherein the freezing point depressant is selected from the group consisting of sodium nitrite, urea, glycerol, monoethylene glycol, ethyl alcohol, mixtures of sodium nitrite and urea mixtures of sodium nitrite or urea with sodium chloride.
26. An ice-preventive and deicing material in accordance with claim 11 wherein the aqueous solution also contains a humectant selected from the group consisting of sorbitol and glycerol.
27. An ice-preventive and deicing material in accordance with claim 11 wherein the emulsion also contains a compound selected from the group consisting of polyisobutylene, polyethylene glycol, glycerol, low molecular weight polyethylenes, sugars, and hydrogenated castor oil for imparting visco-elastic and thixotropic properties to said emulsion.
28. An ice-preventive and deicing material in accordance with claim 11 wherein the water-absorbing, viscositymaintaining compound is a compound selected from the group consisting of cellulosic, proteinaceous, and starch materials and clay minerals.
29. An ice-preventive and deicing material in accordance with claim 21 wherein the cellulosic material is carboxymethyl cellulose.
References Cited UNITED STATES PATENTS 2,716,068 8/ 1955 Fain et al. 252 2,731,353 1/195'6 Fain et al. 25270 2,905,642 9/1959 Miller et a1. 25273 3,085,889 4/ 1963 Swift 25270 3,147,223 9/1964 Boies et al. 252-75 3,185,648 5/1965 Standish et al 252-70 LEON D. ROSDOL, Primary Examiner I. GLUCK, Assistant Examiner U.S. Cl. X.R.