US 2929789 A
Description (OCR text may contain errors)
iinite State SOLVENT, CARBON LOOSENER Charles F. Pickett, Bel Air, Robert E. Wagner, Jr., Havre de Grace, and Myer Rosenfeld, Baltimore, Md., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Application November 23, 1956 7 Serial No. 624,176
4 Claims. c1. 2s2-1ss (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalties thereon.
This invention relates to the removal of carbon deposits from parts of internal combustion engines. More particularly the invention relates to a carbon-loosening solvent suitable for use in softening and facilitating the effective removal of carbon, gum, oil, tar and other surface contaminants, except rust and corrosion, from items such 2 as pistons, piston rings, carburetors, fuel pumps, and engine assemblies.
Various degrees of difficulty exist in the removal of socalied carbon deposits, depending on the particular conditions of operation of the engine, the nature of the lubricating oils, the nature of the fuel, and the type of metal used in the manufacture of pistons. Variations in the resistance to removal of such carbon deposits are as wide as the variations in the types of contaminants formed on the engine parts. For example, so-called light carbon deposits are readily removed where the chief active component of the carbon-loosening solvent is cresylic acid. Other types or" carbon deposits are more dilficult to remove, however, and require cleaning compositions which contain both cresylic acid and chlorinated solvents. Cresylic acid type compounds, however, are undesirable because of their toxicity, diificulty of disposal, and their limited supply which might well become critical at times of national emergency. Chlorinated compounds are also undesirable because of their toxic hazards. As a general rule, the smaller the molecule of the cleaning compound the faster its speed of cleaning. For example, methylene chloride has been found to be one of the most eifective cleaning compositions when used as one of the principal active components of carbon-loosening solvents. Methylene chloride has the relatively high M.A.C. value of 500 p.p.m., that is, for safety purposes, the maximum allowable concentration of methylene chloride vapor in the air is approximately 500 parts per million. Where concentrations of methylene chloride exceed that figure, a definite toxic hazard is presented. Since engine parts to be cleaned are either dipped directly intocontainers of solvent or the solvent is brushed on the parts and allowed to stand for several hours before removal, the concentration of solvent in the air merits serious consideration. In spite of its relatively high M.A .C. value, however, methylene chloride is undesirable for use as acarbon-loosening solvent since it has alow boiling point of 104 F. and its M.A.C. value is far exceeded at many ambient temperatures. For example, at 72 F. the concentration of methylene in the surrounding air would be in the neighborhood of 500,000 p.p.m. For purposes of this invention, a nontoxic cleaner is defined as one which is usable at temperatures at which each of the ingredients has a vapor concentration below the M.A.C. value for that ingredient.
Accordingly, the primary object of this invention is the formulation of a cleaner having a cleaning ability equal to that of cleaners containing a combination of chlorinated hydrocarbons and cresylic type compounds but in 2329,78 Patented Mar. 22, 1%60 which chlorinated hydrocarbons of the naphthenic, aliphatic or aromatic types, as well as cresols, phenols, and their related compounds or their salts are absent.
A second object of this invention is the formulation of a carbon-loosening solvent having a desired degree of cleaning ability, but in which the vapor concentrations of hazardous components are kept below their maximum allowabie concentration values at the temperature of use.
The further object of this invention is the provision of compositions for removing carbon deposits which will remain stable and effective over a wide range of conditions.
Pursuant to the above mentioned objects of this invention, we have found that mixtures of monoethanol amine, water, and ethylene glycol mono-butyl ether provide the desired degree of cleaning ability even in the absence of chlorinated hydrocarbons and phenolic or cresylic type compounds. When this base is used, it has been found possible to adjust the composition in such a manner that the vapor pressures of all components lie below their M.A.C. (maximum allowable concentration) values even at temperatures as high as F. At a temperature of 130 F. the desired degree of cleaning is generally obtained in approximately four hours or less, which is considered adequate for all practical purposes.
It has also been found that additional improvement in cleaning may be obtained by the addition of small amounts of propylene glycol (0.5-l.2% by volume of total cleaner) or ethylene glycol (0.30.8% by volume of cleaner) and by substituting ethylene glycol monoethyl ether in all or part for the corresponding butyl ether, moi. for mol. The upper concentration of this ethyl ether, however, must be limited if its vapor concentration 'is to be maintained below its M.A.C. value at 130 F. In removing carbon deposits from engine parts, brushing with a bristle brush is usually required subsequent to soaking in the cleaner composition. Brushing is sometimes difiicult, however, if no soap or detergent is present. Accordingly, it is advantageous to include some soap or detergent in these cleaner compositions.
It has also been found that the same degree of cleaning may be obtained by substituting, in part, aromatic hydrocarbons or mixtures of such hydrocarbons for the ethylene glycol mono-butyl ether. Typical characteristics of aromatics which have properties lying in the proper range of cleaning and which have vapor pressure characteristics enabling them to be properly utilized for the purposes of the low toxicity cleaner of this invention are:
ASTM Method D86-52.
Other aromatic hydrocarbons may be used in cases where vapor concentrations are not a factor. In order to prevent gelation which may occur on evaporation of volatile solvents, it may be desirable in some cases to add small amounts of a gelation inhibitor or phase stabilizer. In this respect either 3 methoxy butanol or hexylene glycol in concentrations of from 1 to 5 percent by volume of the total cleaner has been found to be eifective. Additionally it is frequently advisable to add a corrosion inhibitor to the cleaner of this invention, particularly where metals such as zinc, copper, brass, lead, or aluminum are being cleaned. Sodium silicate has been found to serve effectively as a corrosion inhibitor. Only small amounts of sodium silicate have been found to be necessary to prevent corrosion. Excess silicate settles to the bottom of the mixture and the clear supernatant liquid may be used directly, or it may be filtered by means of ces-ass n v to any of the usual filter media such as paper mat and the like. 7
Although monoethanol amine is used in the preferred modification of this invention, other types of primary hy droxyamines may be used in its place. A primary hy- 4 of this invention are: Soap to 23%; aromatic hydrocarbons 0 to 65%; ethylene glycol mono-butyl ether 7 to 64%; mono ethanol amine 2 to 27%; water 3.5 to 57%; 3 methoxybutyl alcohol 1 to 3%; propylene glycol 0.5 to 1.2%; ethylene glycol 0.3 to 0.8%. In mols per liter,
The ranges of percent by volume in which the components may be used if incorporated in the cleaning composition and which are considered to be within the scope droxyamine is essential, however, to obtain proper cleanethylene glycol moilo-butyl ether varies from .534 to 4.90 ing. Other types of amines, for example, diethanol and mono ethanol amine varies from .335 to 4.52, amine, diethylethanol amine ,or tri'etllanol amine have While the instant invention has been shown and deyielded poor results. scribed herein in what is conceived to be the most prac- The low vapor pressure of the hydroxyaniines is believed tical and preferred embodiment, it is recognized that dedue to the association of the hydroxy group of molepartures may be made therefrom within the scope of the cule with the amine group of another, through hydrogen invention, which is therefore not to be limited to the debonding. This associated molecule apparently breaks tails disclosed herein but is to be accorded the full scope dOWIl readily give the Ifiactiofis Characteristic f an of the claims so as to embrace any and all equivalents. amine- Th8 eificiency mono-631mm aminfi in C What is claimed and desired to be secured by United junction with the water and the ethylene glycol 11lono $1 1 Letters Patent is: butyl ether (alone or in part substituted by aromatic hy- W lai I drocarbons) may be due to the independent action of 1. A non-toxic, carbon-loosening composition consistthe various cleaner components on the components of lag entially, by volume, of from 2 to 27 percent of the carbon deposits, with various degrees of lipophillc and a primary hydroxyamine selected from the group conhydrophilic character. Too much of one component resisting of monocthanolamine and monopropanolamine, Suits in too little, l'eiativfiil, 0f the Oihfifs, 80 that of from 7 to 64 percent of an ether selected from the boil components are not removed which would othergroup consisting of ethylene glycol monobutyl ether, wise expose it to soluble carbon components. Also, ethylene glycol monoethyl ether, propylene glycol monoditlerent particles of even the same soil molecule, micelle, butyl ether, ethylene glycol monopropyl ether and ethylor larger particle may successively become solvated with one monophenyl ether, of from 3.5 to 57 percent Water the proper solvent. Insutiicient quantities could result and of from 0.3 to 1.2 percent of a polyhydric alcohol in the displacement of equilibria so that desolvation is selected from the group consisting of ethylene glycol and favored before complete dispersion of the molecule, mipropylene glycol. celle, or larger particle can occur. 2. A composition as "set forth in claim 1 containing The following specific examples are given by way of 11- from 1 to '5 percent by volume of a phase stabilizer lustrating the practice of this invention. It should be unselected from the group consisting of methoxy butanol derstood, however, that monoproponol amine may be suband hexylene glycol. stituted mol. for mol. for the monoethanol amine in all the 3. A composition as se't forth in claim 1 containing a illustrations given below. Also, propylene glycol monosodium silicate corrosion inhibitor; outyl, or monoethyl or mono-isopropyl ether, ethylene gly- 4. A non toxic, carbon-loosening composition consistcol mono-propyl or isopropyl ether and ethylene glycol iiig essentially, by volume, of from 2 to 27 percent monornono-phenyl ether may be substituted mol. for mol. for 'ethanolarnine, of from 7 to 64 percent ethylene glycol the ethylene glycol monobutyl ether given in the below ilmonobu'tyl ether, of from 3.5 to 57 percent water, of lustrations. Molecular volumes in milliliters may be obfrom 0.5 to 1.2 percent propylene glycol, and of from 1 tained for these substitutes by dividing the densities of to 5 percent methoxybutanol.
Example No 1 2 a 4 s s 7 s 9 10 11 12 13 14 15 16 17 Soap 1e 1e 1e 1e ls 16 15.8 23 10.5 Aromatics 45.6 45.3 8.5 41.4 64.8 13.1 34.1 39.0 Ethylene Glycol Mono-Blltyl Ether. 30.4 30.2 10.5 27.6 7.2 64 23 13.8 21.9 25.4 19.4 11.9 12.0 9.5 0.6 12.6 12.0 Mono-EthanolAmine 5 a 25 2 s 7 22 19.1 4.2 4.0 21.5 21.0 21.2 21.0 21.2 22.3 22.8 Viater a 3.5 10 1a 7 13 24:38 16:8 19.6 53.7 52.0 52.5 52.0 52;! 55.1 513.4 Propylene Glycol .76 1.1 1.1 1.1 3-MetlloXy-Bl1tylA ol 1.47 2.1 v
Sodium Silicate, 40 .12 0.1 0.3 0.5 0.3 0.5 Ethylene Glycol Mono-Ethyl Ether 1.47 2.1 Ethylene Glycol Mono-PhenylEtller. 7 0 7 1 9.4 9.5 Hexylene Glycol 4.8 4.8 4.8 4.8 Synthetic Detergent 1.9 1.9 1.0 1.9
these substances into their molecular weights. All vol- 55 References Cited in the file of this patent umes are measured between F. and F. and all UNITED STATES AT values are in percent by volume unless otherwise specifi- 11 34 Amthor at 7, 1936 Cally deslgnatefi; 2,089,212 Kritchevsky Aug. 10, 1937 The compositions given m above Examples 3, 7, 8 and 2,097,737 Pickett et a]. p Nov. 2' 1937 11-13 represent preferred embodiments of the invention 60 355 7 7 Bowman Aug 2 44 in view of the fact they possess the low M.A.C. values 2,3 3,114 p vi l Aug 21, 194.5 desired in this type of composition. 2,466,632 B01115 Apr. 5, 1949 In compositions using soap, where aromatic hydrocar- 2,509,197 Borus et a1. May 30, 1950 bons are used, it is desirable that the percentage of soap 2,566,298 Irwin Sept.'4, 1951 be between 10 and 23 percent. In the absence of aro- (55 "2,576,419 Sccfist Nov. 27, 1951 matic hydrocarbons, approximately 2 to 23 parts per volume of soap or synthetic detergents are added tocom- I 4 OTHER R positions. Such additions much improve the ease of Qi y F -j by Carbldeand Carbon brushing Chem. Corp.,' New York (1950).
7o Hexylene Glycol (Tech. Booklet SCzSO-l), pp. 8-1 2,
15, 191116 25, Pub. by ShellChel'n. Corp., New York (1950).