US 3167514 A
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United States Patent I h ce fliilfil l Fatented Jan. 2%, 1%65 3 167,514 CDMPOSlTlONS FGll CLEANING MACHENERY AND ELECTRECAL EQUWMENT Hayward R. Baker, Silver Spring, lVliL, assignor to the United States of America as represented by the Secretary of the Navy No Drawing. Filed Mar. 7, 1962, Ser. No. 178,21lll 3 Claims. (Cl. 252-170) (Granted under Title 35, US. Code (1952), see. 265) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the pa merit of any royalties thereon or therefor.
This application is a continuation-in-part of application Serial No. 821,333, filed June 18, 1959, for Compositions for Cleaning Machinery and Electrical Equipment, now abandoned.
This invention relates to cleaning compositions for removing oily or greasy contaminations, more particularly to organic compositions which are used as aqueous emulsions for displacing any sort of contamination adhering to machinery, electronic equipment, electric motors and the like.
In the past, aliphatic hydrocarbon solvents that were found useful in oil cleaners or degreasers had relatively low flash points of about 104 F., and such cleaners required the inclusion of certain halogenated hydrocarbon snuifers to reduce fire hazards and to provide increased cleaning power. Chlorinated hydrocarbons, such as dichloroethylene, chloroform, 1,1,l-trichloroethane, which were blended with volatile hydrocarbons for this purpose, have been found to be considerably toxic to workers, as well as corrosive to metals and often detrimental to insulating materials, painted surfaces, resins, plastics, etc.
New and useful compositions have now been formulated in accordance with the present invention which are more effective in removing oily and greasy contaminations from metals and other surfaces and which accomplish this end without the presence therein of any chlorinated or other halogenated compounds. Moreover, said compositions have been found to be substantially non-corrosive to metal parts, less injurious to insulating materials and substantially non-toxic to the workers.
It is therefore an object of the present invention to provide organic compositions which can be readily formed into cleaning emulsions for removing oily, greasy, adherent contamination from metal surfaces and from electrical equipment.
Another object of the invention is to provide novel cleaning emulsions which are highly effective for rupturing oil and grease films and washing away the contaminant material with substantially no mechanical treatment of the surfaces and with considerable savings in time and labor.
A further object of the invention is to provide compositions which are effective in dislodging and washing away adherent lubricants, fuel oils, debris and other coatings, short of dried paint, resins, plastics, etc.
A still further object of this invention is to provide cleaning compositions which are safer to use than previous cleaners for oils and greases in that they do not create fire hazards, are not irritant to the skin and do not adversely affect the cleaned parts.
According to the present invention, organic compositions are formulated which can be readily formed into cleaning emulsions capable of breaking or rupturing adherent oil and grease films. The aqueous emulsions, which are formed at the time of use, are very effective for removing oils, greases, waxes, fats, paint vehicles and thinners, in fact, substantially all adherent films or coatings, except for permanent paint, plastic and resinous coatings. The emulsions formed by means of the present organic compositions provide rapid, easy and complete removal of such contaminants by applying said emulsions in any convenient manner, for example, by pouring onto the contaminant surface, by spraying a light stream of emulsion, or by supersonic agitation in a cleaning tank. Once the cleaner emulsion contacts the contaminant film on a surface, the film is ruptured and pushed back exposing a bare, clean surface; the contamination is rendered non-wetting and it is easily flushed away with additional cleaner or with flushing Water with no recontamination of surfaces over which it is flushed.
The organic composition which provides the cleaner concentrate of the invention consists essentially of (l) a liquid aliphatic hydrocarbon having a flash point of about 140 F., (2) a surfactant or surface active agent of the non-ionic type and of high adsorptive power, and (3) a penetrant which is an oily additive capable of dissolving into and combining with contaminant materials.
The organic composition is now described in greater detail, and the role of each ingredient in the emulsion cleaner is presented in the following specific description.
(1) The present invention provides a liquid aliphatic hydrocarbon which has a hash point of about 140 F. with a boiling range which may extend from about 350 F. to about 450 F. The aliphatic hydrocarbon component may comprise mineral spirits. More specifically, a solvent suitable for this purpose is known as the Dry Cleaning Solvent, Type II, or aliphatic naphtha. The Amsco 140 solvent which is supplied by the American lviineral Spirits Company is essentially an aliphatic hydrocarbon with a close-cut boiling range and possessing a mild odor.
he Initial Boiling Point of this fraction is 364 F, while the fraction thereof has a boiling point as high as 387 F. The flash point determination of this fraction averages about 142 F.
in an oil-in-water emulsion, an aliphatic hydrocarbon solvent with a flash point of about 140 F. is less harmful to electrical insulation than with aromatic constituents or with those containing chlorinated hydrocarbons. It is also desirable to employ a higher flash point solvent than the conventional type cleaners naphtha (of about -104 F.), since a higher flash point solvent obviates the need for any chlorinated hydrocarbon snuffer or other similar components to suppress the combustible nature of solvents. A dash point of'about F. for the solvent, specified in the present invention, has been found to be higher than the flash point of most contaminants with which it comes in contact.
(2) In accordance with the invention, a small amount of surfactant or surface active agent is included in the composition to provide the necessary adsorptive power for breaking and displacing an oily type film. The term surfactant is used in the present specification to indicate a surface active agent, which in conjunction with an aliphatic solvent, has been found to be capable of displacing an oil from contaminated surfaces. This oildisplacing effectiveness is observed when a drop of cleaning emulsion containing a specific surface active agent is placed on an oil film. The maximum area from which the cleaning emulsion clears away the oil to expose a bare surface is taken as an indication of the oil-displacing ability of that surface active agent.
A surface active agent is needed to hold the hydrocarbon in a useful emulsion with water. Therefore, an effective surfactant for use in the present compositions keep the solvent dispersed in an oil-in-water emulsion as well as provides for the complete displacement of oil from contaminated surfaces.
in accordance with the invention, effective oil-displacing and water-emulsifying surface active agents are provided by such commercially available surfactants as Span- 85, Nonisol-i00, Tergitol Nonionic NPX, Pluronic, and Triton Xl55. These surfactants are of the non-ionic type that can be used effectively in emulsions with either fresh or salt Water. Effective non-ionic type surfactants are provided by polyglycol esters of the fatty acids and by polyoxyalkylene derivatives. For example, polyethylene glycol 400 monooleate has been found to be a particularly effective compound for this purpose. The polyethylene glycol ester of lauric acid, sold as Nonisol 100 by Geigy Chemical Corp, is a further example of a polyglycol ester which forms an effective surfactant for the present cleaning compositions. Condensates of ethylene oxide with a hydrophobic base are formed by condensing propylene oxide with propylene glycol (Pluronics). The effective surfactant in accordance with the invention containing the ethylene oxide in an amount in the range of between in about to 30% by weight of the product. The surfactants listed above are included in Surfactants Listed by John W. McCutcheson, published in 195 8, said publication being a reprint from Soap & Chemical Specialties, December 1957, .lanuary, February, March and April 1958. The Nonisol 100 is described in said publication as a polyethylene glycol of lauric acid in which the polyethylene glycol has an average molecular weight of 400. The Pluronics are identified in said publication as condensation products of ethylene oxide with a hydrophobic base which is formed by condensing propylene oxide with propylene glycol.
in simulated tests, emulsions containing 0.25% of polyethylene glycol monooleate provide superior cleaning compositions possessing high cutting and displacing power of oil films, as measured by area size exposed when oil films were acted upon by drops of cleaning emulsion.
The polyethylene glycol monooleate which has been used in the present cleaning compositions has an average polyethylene glycol molecular Weight of between 300 and 600, and the final esterified product is designated as polyethylene glycol 400 monooleate. In addition to its adsorptive power this material is a good rust inhibitor and affords protection to the clean surface during the cleaning operation and also after the surface has dried by means of a very fine film of the monooleate that remains on the cleaned surface.
A desirable surfactant keeps the solvent mixture dispersed in an oil-in-water emulsion only until the solvent droplets touch the surface of the contaminating film. Non-ionic type surfactants which have been found useful for the present invention are included in the organic solvent mixtures in an amount of about 1 percent or less by weight in order to provide an unstable emulsion which remains dispersed until the emulsion contacts the film surface. Upon contact, the solvent is immediately released to break and push back the oil film. The preferred concentration of surfactant is in the range of about 0.5 to about 1.0 percent by Weight of the organic mixture, while a concentration in the order of 0.2 percent or less causes the emulsion mixture to break too rapidly and becomes diificult to use as a light spray.
y (3) Emulsions containing only aliphatic naphtha and a surfactant are able to push back a contaminant film only after the film has been ruptured by strong spray impact to put emulsion droplets in contact with bare surface. In accordance with the invention, a blending agent or penetrant is included in the cleaning composition which is capable of penetrating the' contaminant film and blending with it, enabling the solvent and surfactant to reach the underlying surface. The ability of the penetrant to blend with a contaminant film depends upon its surface tension which should have a value intermediate between the surface tension of the solvent and that of the contaminant film. The solvent has. a surface tension of less than dynes/ cm. While an adherent oily film has a surface tension nearly dynes/cm. or more. The solvent cannot dissolve an oily film readily, but the presence of a blending agent or penetrant with a substantially higher surface tension than that of the solvent and closer to the surface tension of adhering oily films is capable of promoting rapid penetration of oily films.
The inclusion of a petroleum hydrocarbon having physical properties substantially within the following indicated ranges, materially affects the performance of the present cleaning emulsions and adapts them to the displacement of many contaminant films having surface tensions from 26-3Z dynes/cm'at 25 C.
DI S'IILLATION Fraction: Boiling range, F. 10% 425 to 500 50% 490 to 530 665 to710 End point 715 to 750 PROPERTIES OF THE PENETRANT COMPONENT Viscosity F. 2.0 to 6.0 centistokes.
Flash point to 250 F. Pour point Less than0 F.
romatic content 10 to 25 Surface tension 27.0 to 30.0 dynes/cm. 25C.
A turbojet lubricating oil, Grade 1005, used on jet engines and conforming to specification, MilO-6081B, has been found to be an effective penetrant that promotes rapid penetration of oily films. Also, a diesel fuel oil, Type I, designed for engine speeds over 1000 rpm. and which meets specification, Mil-F-16884C is characterized as a distillate engine oil with no cracking materials therein, but one that may contain certain suitable additives to improve the performance of the oil. The oil provides substantial penetration into adherent films when it is used as a penetrant in the present emulsion cleaners.
The physical properties of said penetrants are listed in the table below:
h Jet engine Diesel Oil Distillation lubricant (Mil-F- (Mil-O- 168840) 486 426 527 495 90%-- 706 668 End point 747 718 Viscosity 100" I 5. 6 4. 8 Flash point F" 232 158 Four point F. 65 40 Aromatic content. ..-.percent. 17 12 Surface tension... .....dynes/cm. 25 0.. 28.0 27. 6
The oil penetrants mentioned above have great penetrating power, are capable of promoting the dissolution of almost any oily contaminant and may be used against fuel oils, diesel oils, parafiins, gear oils, diesters, polyesters, polychlorophenyls, polypropylene oxides, silicone oils, fluorocarbons, heavy grease materials and asphaltic residues. 1
The cleaning compositions are normally mixed with about an equal volume ofwater in forming emulsions,
although the organic mixture form s useful emulsions in concentrations of between about 5-60 percent by volume. Low concentrations of organic mixture have been found useful forcleaning :salt water residues. The emulsion mixturesare effective with either fresh or sea water. Cleaning emulsions are formed with lesser amounts of sea Water. It will be appreciated that sea water emulsions necessitate a fresh water rinse to prevent salt deposition on the cleaned surfaces. are formed by simply agitating the organic composition mixture with the water layer. The emulsions are not toxic or irritating to the skin and the fire hazard is considerably minimized so that no special handling of the emulsions is necessary. r a i The emulsions The organic composition of the present invention may be varied within the following ranges.
Component: Percent by weight Aliphatic hydrocarbon, flash point 140 F. 89.5 to 96.5 Penetrant 3 to Surfacant 0.3 to 1 The invention is further illustrated by the following Nonisol X-100 Water (percent by vol.)
Example III Component: Percent by weight Aliphatic hydrocarbon, flash point 140 F. 89.5
Turbojet lubricating oil, Grade 1005 10 Polyethylene glycol 400 monooleate 0.5 Sea water (percent by vol.) 20
The composition may be used as a spray cleaner, the solvent mixture is mechanically mixed with water in any convenient manner and the emulsion is sprayed on contaminated surfaces at pressures of about 20 to 80 psi. A spray gun at a pressure of about 80 psi. assists in the penetration, dispersion and removal of all traces of dirt and oil films without injury to the most delicate insulating materials or electronic devices, even at nozzle-tosurface distances of only a few inches.
Mobile electrical and mechanical structures may be subjected to ultrasonic radiation while immersed in the bath of the cleaning emulsion. The increased agitation drives the cleaning emulsion into recesses of motor parts that are inaccessible by other means.
Following the spray or immersion step, the treated parts are flushed thoroughly with water, either by spraying means or by ultrasonic treatment, to remove all cleaning emulsion and traces of oily contamination and dirt. The cleaned parts are then air-dried, preferably by directed streams of compressed air. For further complete drying the parts may be blown with heated air.
The invention, therefore, discloses cleaning compositions which are both economical and safe to use, that effectively remove oily and greasy contaminants without scrubbing or rubbing oily films and that are effective in cleaning machinery and electrical equipment by applying the cleaning emulsions to an oily contaminant and flushing away the loosened contamination.
Obviously many modifications and variations of the invention may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.
What is claimed is:
1. An organic composition which forms an aqueous cleaning emulsion, said composition consisting essentially of 89.5 to 96.5 percent by weight of an aliphatic hydrocarbon having a minimum flash point of about 140 F., of 3 to 10 percent by weight of a penetrant oil from the group of oils consisting of diesel oil and light lubricating oil, said oils having a surface tension of between about 27 to 30 dynes/cm. 25 C. and of 0.5 to 1 percent by weight of polyethylene glycol monooleate having an average polyethylene molecular weight of about 300 to 600.
2. An organic composition which forms an aqueous cleaning emulsion, said composition consisting essentially of 89.5 to 96.5 percent by weight of an aliphatic hydrocarbon having a minimum flash point of about 140 F., of 3 to 10 percent by weight of a penetrant oil which is a diesel oil having a surface tension of about 27.6 dynes/cm. 25 C., and of 0.5 to 1 percent by weight of polyethylene glycol monooleate having an average polyethylene molecular weight of about 300 to 600.
3. An organic composition which forms an aqueous cleaning emulsion, said composition consisting essentially of 89.5 to 96.5 percent by weight of an aliphatic hydrocarbon having a minimum flash point of about 140 F., of 3 to 10 percent by weight of a penetrant oil which is a light lubricating oil having a surface tension of about 28.0 dynes/cm. 25 C. and of 0.5 to 1 percent by wei ht of polyethylene glycol monooleate having an average polyethylene molecular weight of about 300 to 600.
References (Iited by the Examiner UNITED STATES PATENTS 2,208,524 7/40 Darsey et a1 1486.15 2,613,186 10/52 Pickett et al. 252l 2,866,726 12/58 Vance 252171 X OTHER REFERENCES Bennett: The Chemical Formulary; vol. 1 (1933), page 153.
Goldsmith: Chemical Industries; March 1943, pages 327-8. JULIUS GREENWALD, Primary Examiner.
JOSEPH R. LiBERMAN, ALBERT T. MEYERS,