US2466645A - Cutting oil base - Google Patents

Description

Patented Apr. 5, 1949 STATES PArENr orrics Muckerheide, Silverton,

Ohio, assignors to Emery Industries, Inc., Cincinnati, Ohio, a corporation of Ohio No Drawing. I Application November 1, 1944, Serial No. 561,504

This invention relates to cutting oils, that is, compositions consisting essentially of mineral oil but characterized by their ability to emulsify with water. The emulsions produced from such cutting oils are used in the machining of metals for the purpose of cooling the metal cutting tool and providing lubrication for the chips at the cutting edge. Thus, a cutting oil consists, generally speaking, of a mineral oil containing an emulsifying compound capable of producing an emulsion of the oil in water.

This invention is addressed, more particularly, to cutting oil bases, that is, compounds adapted to be added to ordinary mineral oils to endow them with emulsifying characteristics.

This application is a continuation in part of our earlier application, Serial No. 443,842, filed May 20, 1942, now issued as United States Patent No. 2,392,927, dated January 29, 1946.

When cutting oils first came to be used in the metal trades many years ago they contained a great variety of different materials, the composition of the product of each manufacturer being the nature of a proprietary made up to suit a given machine shop's requirements. Because of the relatively delicate proportioning required to produce emulsions with the compounds then available, each batch of cutting oil was adjusted chemically upon the basis of its ability to emulsify the particular grade or type of mineral oil from which the cutting oil was to be produced. There was always substantial variation from batch to batch, and even so, the actual emulsifiability of the oil in water was poor as judged by the specifications of the present day. Most of the original compositions were mineral oils containing a limited quantity of fatty acid soap, sometimes naph thenic acids and sometimes free fatty acids for the purpose of enabling the soaps to dissolve in the mineral oil. The acidity frequently caused corrosion of the metals.

In more recent years oil soluble mineral oil of cutting oil base, consisting chiefly of mineral oil sulphonates, have been used in recent years in cutting oil production, the base being added to the oil at the refinery and the resulting cutting oil then being shipped to the consumer.

The chief dimculty with the use of mineral 1 Claim; (01. 252-42) oil sulphonate cutting oil bases has been their intolerance to variations in the type or quality of oil they were to emulsify. Each time a batch of cutting oil was made up, adjustments in chemi cal composition would have to be made and emulsifying assistants would have to be added to the compositions in order that their emulsifying characteristics would conform to prescribed standards. The problem was not merely one of add-, ing more of the emulsifying base; if a suitable emulsion could not be obtained by using. 10% of base sulphonate, it was the experience, always unexpected and disappointing, that a suitable emulsion could still not be obtained by using 12, 15 or 20%. In order to obtain a satisfactory emulsion under such circumstances some ex: traneous material, such as diethylene glycol. would have to be added. Obviously, the procedure of making chemical adjustments each time a batch of cutting oil base was to be made was both tedious and expensive. Moreover, a base suitable for emulsifying the oil produced at one refinery would not be capable of producing a suitable cutting oil upon admixture with the oil from a difierent refinery.

With the more widespread use of cutting oil in all machine trades, this necessity of making chemical adjustments has become a problem of serious importance and, to avoid it, the objective of the present invention has been to produce cutting oil bases which are at least as inexpensive as the sulphonate bases which we have had available in the past, but better than sulphonate bases, because of their tolerance to variations in oil, their tolerance to variation in water conditions and because of the strong and powerful emulsifying action they are capable of exerting on a variety of types and grades of oil. The objective, in other words, has been to produce a cutting oil base capable of emulsifying the different kinds of oil produced at the different refineries throughout the country, and of emulsifying such oil with the varying kinds of water found at manufacturers plants.

We have discovered that a cutting oil base consisting essentially of rosin soap of an alkali metal and a fatty acid mono ester of a poly or dihydrlc alcohol is capable of giving these desirable results. A typical base of the present invention consists of substantially 1 part of fatty acid mono ester to each 1 to 2 parts of rosin soap.- The proportions are quite critical, otherwise the desired universal emulsifying characteristics are not obtained.

It has been appreciated in the past that the fatty acid mono esters are capable of carrying fatty acid soaps into solution in mineral oil and admixtures of glyceryl mono oleate and red oil or oleic acid soap are known as emulsifying agents. Such compositions, however, are not suitable as the principal constituents of cutting oils for several reasons. If they are in the proportions in which rosin soap to fatty acid mono ester is present in the compositions of this invention, the red oil soap is incapable of dissolving in the oil. And, while more of the fatty acid mono ester is capable of causing the red oil soap to dissolve in mineral oil, the oil then either gels and loses its fluid characteristics or does not emulsify in water In the same manner that a soap of a fatty acid does not give satisfactory results when combined with a mono ester of a fatty acid, bad results also are obtained when the effort is made to combine a rosin soap with a rosin mono ester; the resulting product is insoluble in oil.

In contrast with these results, there is a peculiar and very desirable response to fatty acid mono esters by the rosin soap. Such a material, when in the proper proportion to the mono ester, is capable of exerting the required emulsifying action upon a variety of mineral oils and of emulsifying such oils with a variety of different types of water, both acid and alkaline. The base itself is a substantially neutral composition and exerts no corrosive action on metals.

The products of the present invention therefore, which are capable of providing the desired emulsifying properties as well as the toleration to variations in both the oil and water with which they subsequently are admixed, consist essentially of an alkali metal soap of rosin and a fatty acid mono ester of a polyhydric or dihydric alcohol.

The rosin soap is soluble in the partial ester and this solution is a clear liquid which readily dissolves in mineral oil and which, when dissolved in mineral oil, imparts to it the property of readily emulsifying in water.

The alkali metal of choice which is used for saponifying the rosin is potassium, the rosin soap thus being, chiefly. potassium abietate. Sodium may be employed as a substitute for potassium in saponifying the rosin, though the base is heavier.

The term rosin soap is used throughout the specification and claims to denote the potassium or sodium salts of rosin. In this case it is usually desirable to dilute the base with mineral oil in order to make it sufficiently thin to be poured from shipping containers without difficulty.

The fatty acids adapted to be employed in the practice of the present invention are preferably liquid fatty acids obtained from natural fats and preferably fatty acid containing from sixteen to eighteen carbon atoms in chain length as, for example, oleic acid, corn oil fatty acids, soybean fatty acids and the like. The solid fatty acids and particularly the mono esters of them are less soluble in mineral oil than the mono esters-of the liquid fatty acids and sometimes tend to crystallize out of the oil if the composition becomes chilled.

Ethylene glycol, diethylene glycol, glycerol and the like are typical alcohols which may be employed in the preparation of the present compositions. However, as between the poly and dihydric alcohols, the polyhydric alcohols are preferred inasmuch as, in the present compositions, the polyhydric alcohol esters are much more effective than the dihydric alcohol esters in promoting. emulsiflability and the solubility which is 4 desired. For these reasons the esters of the dihydric alcohols may be considered as the partial equivalents, not the full equivalent of the polyhydric alcohol esters in the practice of this im- 5 provement. In general, wood rosin is preferred to gum rosin in the preparation of the rosin soap employed in the compositions. In the manufacture of the present cutting oil base the mono ester and the rosin soap are preferably made independently of one another and then admixed in the proper ratio. The mono ester is made by heating glycerine and fatty acid to a high temperature until the free fatty acid has been reduced to about two per cent. While the ester is warm, rosin is added in the desired proportion and the ester and the rosin are then admixed. The rosin is more easily saponifled directly. Potassium hydroxide, sufficient in amount to saponify the rosin is then added, and after saponification is complete, the cutting oil base is ready for use.

A typical cutting 011 base of the present invention is of the following proximate analysis:

Potassium rosin soap parts by weight..- 45 Glyceryl mono oleate do 35 Red oil soap do 5 Water per cent 7.5

If desirable, oil soluble mineral oil sulphonates may be used as emulsifying adjuncts in the present compositions up to approximately ten or fifteen per cent by weight. A feature of considerable importance in this respect is that the presence of sulphonates in the present cutting oil bases does not disturb or destroy their toieration for variations in the quality of oil which they are capable of emulsifying. This fact enables the manufacturer to include sulphonates in the 0 composition when the price of rosin is high and, conversely, to exclude sulphonates when they are in demand, thereby keeping the cost of the product at a minimum under fluctuating market conditions. Mineral oil sulphonates up to approximately forty per cent by weight may be employed when desirable.

In the manufacture of cutting oils from these bases the proportion utilized ordinarily resides in the range of twelve to twenty parts of base to each one hundred parts of mineral oil.

In contrast with the mahogany sulphonate type cutting oil bases that have been available in the past, the duality of an emulsion obtained by the bases of the present invention is influenced by the amount of base employed. If a poor emulsion is obtained using a given amount of base, a good emulsion can readily be made, except under unusual conditions, by using a larger quantity. This property enables each cutting oil manufacturer necessary emulsion with the particular mineral oil from which the given cutting oil is being made.

We have found that the best method of producing a cutting oil base of the type described, particularly from the point of view of cost, is to manufacture this base from tall oil.

Tall oil is a dark brown, viscous material with a characteristic, unpleasant odor. It is obtained as a .by-product in the production of paper pulp by the sulphate process. Tall oil comprises essentially unsaturated fatty acids of eighteen carbon atoms and rosin acids together with a small quantity of unsaponiflable matter. There is considerable variance in composition of this til to use a minimum quantity of base to produce the material, but an average composition may be as follows:

The color and the odor of tall oil more it unsuitable for a great many purposes and also impose great diiiiculties in the way of obtaining the acids contained in it in conditions sufllciently pure to enable them to be used for conventional purposes. From the point of view of a cutting oil base, however, the color and odor are in no way disadvantageous or objectionable and the impurities. that is the materials other than acids, in no way interfere with the treatment of tall 011 by which it is converted into the type of cutting oil base disclosed herein or with its desirable properties as a cutting oil base afterbeing so treated.

We have discovered that when tall 011 is esters fled with one or more of the polyhyric alcohols to form partial esters, that is esters in which all of the hydroxyl groups are not esterlfled, the fatty acids present esterify in preference to the rosin acids. Thus, esteriflcation yields an admixture of rosin acids and partial glycerides of fatty acids. The rosin acids may then be saponifled with an alkalin solution, for instance, a strong solution of caustic potash.

The homogeneous solution of rosin soap in partial ester so formed is generally soluble in light mineral oils at a concentration of fifteen per cent or more by weight and it is capable of emulsifying such oils. In order to improve certain emulsifying and physical characteristics of the mixture small amounts of coupling agents, such as glycols and glycol ethers, may be added.

It should be understood that the esteriflcation is not so specific that only fatty acids are esterifled. Under the conditions employed small. amounts of rosin acids are also esterified. In

' most cases, in order to arrive at a satisfactory balance of the partial esters of the fatty acids and the soaps of the rosin acids, a small percentage of the fatty acids must go unesterifled and, as mentioned above, a small amount of rosin acids must be esterified. Those fatty acids not esterifled are saponified together with nearly all the free rosin acids.

The polyhydric alcohols used in our inventio may be selected from the dihydric, tri, tetra, etc. In general, we have found that the dihydric alcohols form partial esters which are not quite as potent in solubilizing rosin soap in oil and frequently it is necessary, when they are used, to add a small amount of an oil soluble coupler, such as glycerol mono oleate, to insure complete 011 solubility of the rosin soap.

By replacing part of dihydric alcohol with smaller amounts of tri or higher polyhydric' alcohols it is possible to obtain oil solubility without the addition of an oil soluble coupler.

A number of factors must be carefully controlled to obtain the optimum benefits from our invention, namely:

(1) Use a total quantity of polyhydric alcohol' equal to 100-300%, but preferably Mil-200% of the quantity required to provide one OH group for each fatty acid carboxyl group present in the tall oil.

(2) Conduct the esteriflcation quickly. This is best done by pre-heating the ingredients prior to mixing to avoid the slow esteriflcation which frequently results from mixing the cold ingredithese limits is best suited for our process.

Q 6 cuts and then bringing them up to operating temperature. Temperatures of 140-200 C. are the most desirable when the esteriflcation is carried on without the benefit of catalysts. When catalysts, such as the mineral acids. are employed, {lag temperature may be conveniently dropped to (3) The reacting mix should be heated until the acid number of the mix is decreased to 40 to 60% of the original value of the tall oil. When the desired acid number is reached, heating should be discontinued at once and the product cooled to prevent the formation of excessive amounts of resin acid esters or mixed rosin-fatty esters.

Soluble cutting oil bases formed by saponifying the remaining rosin acids of an esterifled mix, prepared as described, are completely soluble in oil due to the solvent action of the fatty acid partial esters on the rosin soaps. The bases are practically neutral and do not contain a large proportion of free acids. No volatile solvents or alcohols are required to obtain solubilityor smooth emulsitlcation. The rosin soaps produce smooth emulsions which form readily without the formation of lumps or curdy particles which usually result when fatty soaps are employed. Such lumps require excessive stirring to incor-.

porate, and if not incorporated the soluble oil' emulsion may contain less oil than is desirable for the particular cutting operation.

Cutting oil bases so prepared are suitable for use in a wide variety of petroleum oils, 1. e., from naphthenic coastal distillates to the Pennsylvania parafllne types. Final adjustments to secure optimum results with specific oils may be made by the addition of a per cent or so of agents such as alkali, in the order of a few tenths of a per cent, or fatty acids coupling agents in the order of one to five per cent.

The emulsions thus obtained with these bases have such a degree of stability that when a ten per cent soluble oil-ninety per cent water emulsion is placed in a cc. cylinder no oil separates, and not over one-eighth inch of cream separates, after standing twenty-four hours.

In cases where it is desirable to increase the emulsifying potency of these bases and to facilitate the dispersion in water of soluble oils containing them, petroleum sulfonates or naphthenic soaps may be added to the saponifled mix. These soaps are also ideally suited for blending with bases which are deficient in soap. For example, when the esteriflcation has been carried beyond the desired acid number, the addition of sulfonic or naphthenic soaps aid in restoring theemulsifying properties.

Crude tall oil usually contains from forty to fifty per cent fatty acids and from forty to fifty per cent rosin acids and the raw material within However, there are some grades of the crude product which contain a much higher percentage of fatty acids and others containing a greater amount of acid, such as oleic, until the ratio of fatty acid to rosin acid is approximately the same.

Refined tall oil may likewise be used, but for metal working operations the improved color and odor obtained by refining does not Justify the additional cost. Many other variations may be made by those skilled in the art without departing from the scope of this invention.

The following examples are offered to illustrate our invention:

No. I

237.0 parts of crude tall oil having an acid number of 162.4 were heated to 150 C. and blended with a mix of 16.4 parts of glycerine (88%) and 20.1 parts of propylene glycol, also at 150 C. These ingredients were thoroughly agitated and continued to be heated until the temperature reached 160 C. After six hours at this temperature the acid value of the mix had dropped to 83.6 and the material was rapidly cooled to 38 C., following which an aqueous solution of 48% caustic potash was slowly added while agitating and maintaining a temperature of not No. II

474 parts of crude tall oil of same acid number as used in Example I were mixed with 32.8 parts of 88% glycerine and 41.6 parts of propylene glycol. These ingredients were rapidly heated to 170 C. and held at that temperature for 1 hours, after which the temperature was increased to 185 C. for one hour. The mix was cooled to 60 C. Acid number was 64.0. 112.0 parts of sodium sulfonates (58%) were blended with the above ingredients until the resultant product was a homogeneous, viscous liquid. When cooled to 40 C. this liquid was neutralized as in previous example until acid number was 4.0. 3% diethylene glycol was added to produce a clear fluid soluble 011 base. A blend of parts by weight of this base with 85 parts by weight of 100 second parafilne oil formed a soluble oil with the same emulsifying power as obtained in Example No. I.

NO. III

150 parts of crude tall oil with an acid number of 163.0 were heated to 130 C. and 26.0 parts of 8 propylene glycol and 3.4 parts of Baum, HsSOi acid added.

The ingredients were thoroughly agitated and raised to temperature of 180' C. After four hours esteriilcatlon, acid number decreased to 74.4 and reaction was stopped. The fluid liquid was neutralized with 45% aqueous caustic potash solution at 40 C. until acid number was 3.2. Then 5% of a mixture of glyceryl mono and di oleate was added to the base and a blend of 18% by weight of this base with 82% of second paramne oil formed a clear solution which readily emulsified in water.

Having described our invention we desire to be limited as to the scope thereof only by the claim which follows:

A method of making a cutting 011 base from tall oil which comprises first esterifying the fatty acids in the tall oil'with a quantity of polyhydric alcohol sumcient to convert said fatty acids to mono esters of the polyhydric alcohol and subsequently saponifying the rosin acids of the tall oil into water soluble alkali metal soaps.

LATIMER D. MYERS. VICTOR J. MUCKERHEIDE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,463,092 Pelly July 24, 1923 1,872,617 Brown Aug. 16, 1932 1,907,920 Wilkin May 9, 1933 1,927,066 Gorsuch Sept. 19, 1933 2,039,377 Adams May 5, 1936 2,086,479 Schrauth July 6, 1937 2,097,085 Fabian Oct. 26, 1937 Re. 20,709 Lister Apr. 26, 1938 2,190,653 Segessemann May 7, 1940. 2,198,851 Wiezevich Apr. 30, 1940 2,233,203 Flaxman Feb. 25, 1941 2,240,365 Dreger Apr. 29, 1941 2,246,467 Kaufman June 17, 1941 2,265,791 Zimmer Dec. 9, 1941 FOREIGN PATENTS Number Country Date 461,715 Great Britain Feb. 23, 1937