Patented May 30, 1933 1911,195

UNITED STATES PATENT OFFICE RAYMOND J. KEPFER, OF WILMINGTON, DELAWARE, ASSIGNOR, BY MESNE ASSIGEN MIENTS, TO E. I. DUPONT DE NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE NONCORROSIVE ANTIEREEZE LIQUID No Drawing. Application filed November 15, 1930. Serial No. 496,033. This invention relates to a new composi num, iron, or other metals found in such tion of matter having both non-corrosive apparatus by the water or acidic impurities and anti-freezing properties and which is present and with the assurance that, even particularly adapted for use in the cooling though the temperature of the solution be systems of water-cooled internal combustion comes excessive, there will result substan- 5; (ellig Ines. - tially no corrosion of the metal surfaces. It is well known that in the operation of The borates which I have found particu automotive vehicles, particularly in the win larly applicable for use in such compositions ter months, it is necessary, when using those employing water-cooling systems, to use as of matter include the alkaline earth and al a cooling medium a liquid which will not. kaliboratesparticular alcohol which usedare bothand, solubleof course, in thein as freeze under the conditions of operation. Water. I have found that borax, which is Various so-called anti-freezing liquids have comparatively inexpensive and has these S been proposed for this purpose, such, for qualities, is especially suitable; while under example, as ethyl alcohol, giycerol, ethylene some circumstances the organic borates, such ry glycol, and aqueous solutions of inorganic as methyl and ethyl borate, may be em GS, salts. The polyhydroxy alcohols which are ployed, their use is not highly recommended lised to some extent have proven rather ex as they are not readily availabie, have a low pensive when leaks occur in the cooling sys vaporizing temperature, and show no ap tenns; the ein loyment of inorganic saits in preciable advantage over the less expensive f the radiator solutions are prone to effect un borates. If the organic borates be used, they 6 de Cori')sion of the various parts thereof, likewise, of course, should have the solubili and while ethyl alcohol has proven to be in ty characteristics of the preferred inorganic expensive, nevertheless when used alone, it borates, i. e. they should be solubie in water effects considerabie corrosion of the metal and in the alcohoi used. rE. parts of the radiators in contact with it. have determined that to afford adequate in object of the present invention is to protection from corrosion of metalic sur provide a composition of matter which not faces in contact with 76–100% or better () Only has a low freezing point, but likewise Commercial grade methanol solutions, ap inhibits corrosion. A further object of this proximately 0.05% borax is all that is usual invention is to provide such a composition ly rrouired to render such solutions non-cor 3. of matter, particularly for use in internal rosive, Alcohols of higher purity require ("ombustion engines, and in which the cor less, while wood alcohols containing appreci 3 5 rosive action of the anti-freeze iiquid and able amounts of pyroligneous acids or syn the water is inhibited. Other objects will thetic methanol which has not been entirely hereinafter appear. freed from acidic constituents may require i have found that a solution containing up to 0.5% borax to insure full protection. the water soluble lower aliphatic alcohols As the concentration of the alcohol decreases . and principally (thanol, methanoi, and prop a larger amount of borax is generally neces anol, in which there has been dissolved a sary. For example, an aqueous methanol so boiate which is not only soluble in the par lution containing 7.5% methanoi can be ren 90 ticular alcohol employed but which likewise dered non-corrosive by having present ap has an appreciable solubility in water, af proximately .1% borax while a solution con 45 forts a solution which has exceptional cor taining but 15% methanol in water should losive inhibiting qualities together with a contain from 0.5 to 1% borax. It will be 2. freezing point proportional to its alcohol realized, therefore, when employing a con content. Such a composition may be used centrated or dilute methanol solution in in the cooling systems of internal combus Water an unusually small percentage of tion engines without fear of the corrosion of borax will render it substantially non-cor the Oxidizable metals such as brass, alumi rosive. 2 1,911,195 The unexpected advantages of my compo should be prepared by first dissolving the sition may be shown by comparing a steel borate in the alcohol and then adding the drum containing a 75:25 methanol water clear solution to the water. The amount of mixture with 0.1% borax, with another drum methanol or other aliphatic alcohol required 5 containing an identical mixture without the to give the desired lowering of the freezing 0. borax, corrosion will generally appear in the point will be determined, of course, by the latter drum in as short a time as 24 hours, amount thereof added to the aqueous solu while the first drum will show no corro tion. The amount of methanol required to sion even after months in storage. The same be added to obtain protection to a certain 75 O freedom from corrosion, even afterY a temperature below 32 F. is approximately winter's driving, will be obtained in an auto 1% by weight of methanol for each degree mobile radiator holding an anti-freezing Fahrenheit. mixture of, say, 30% methanol, and 70% Warious changes may be made in the pro water in which approximately 0.7% borax portions and in the types of alcohols and 5 has been dissolved. borates employed, providing the alcohols be While various aliphatic alcohols may be soluble in water and borates be both soluble used in conjunction with the borax, prefer in the alcohol and in water, without depart methanol as it has several advantages over ing from this invention or sacrificing any of the other alcohols. As borax is but spar the advantages that may be derived there 20 ingly soluble even in water, particularly at from. 85 low temperatures, the alcohol should prefer claim: ably be a good solvent for it in order that 1. A process for inhibiting the corrosion no crystallization occurs;-and methanol is of the oxidizable metals, with which the a good solvent therefor even below 0° F. liquid and/or vaporized anti-freeze radiator Moreover, a smaller amount of methanol is composition of automobiles is in contact, 90 required to effect the same freezing point which comprises contacting the anti-freeze lowering of a solution than is required for composition containing 15% to 100% syn the higher molecular weight alcohols and thetic methanol with the oxidizable metals consequently it is less expensive to use even in the presence of 0.01% to 3% borax. 95 30 when their cost per gallon is the same. Fur 2. An automobile anti-freeze which is sub thermore, an aqueous solution protected stantially non-corrosive toward the oxidiz against freezing to 20 F. will have a boil able metals of the automobile with which ing point of 1998 F. if methanol is used and it contacts which comprises synthetic meth 1948 F. if ethanol-at 10° F: the relative anol and aborate. 5 boiling points are 193° F. and 187 F., re 3. An automobile anti-freeze which is sub-100 spectively. Obviously a smaller amount of stantially non-corrosive toward the oxidiz methanol will be lost by evaporation under able metals of the automobile with which it similar operating conditions. contacts which comprises 15% to 95% syn I have likewise found that the presence of thetic methanol containing 0.01% te 3% 05 40 borax in concentrated methyl alcohol solu borax dissolved therein. l tions inhibits the corrosion of metallic sur 4. A process for the prevention of the faces in the vapor space above the solution. corrosive action and freezing of radiator Whether or not this be due to the formation solutions, characterized in that a synthetic of methyl borate from the interaction of methanol solution containing borax is dis sodium tetraborate with methanol or due to solved in water to give a solution contain- 0 some other cause, metal surfaces subject to ing at least 15% synthetic methanol and the vapors from such a solution have greater 0.01%In testimony borax. whereof, I affix my signa protection from corrosion than similar solu ture. tions not containing a borate. Ji, 50 An anti-freezing non-corrosive composi RAYMOND J. KEPFER. tion for addition to the water cooling system of internal combustion engines, in accord with my invention, should contain sufficient borax to give adequate protection from cor rosion. This should be true even though the freezing point of the radiator solution is lowered only to a temperature of, say, 15 F. I have found that a concentrated methanol solution containing generally from 1 to 3% 2 60 borax will give the corrosion inhibiting ef fect desired both in the radiator when di luted with water, and in the container prior to dilution. Due to the difficulty of dissolv ing the borates and particularly borax in 65 water I have found that my composition 130