US2670330A

US2670330A - Cutting oils

Info

Publication number: US2670330A
Application number: US187691A
Authority: US
Inventors: Jr Dayton P Clark
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1950-09-29
Filing date: 1950-09-29
Publication date: 1954-02-23
Anticipated expiration: 1971-02-23

Description

Patented Feb. 23, 1954 I CUTTING OILS Dayton P. Clark, Jr., Somerville, N. J., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application September 29, 1950, Serial No. 187,691

7 Claims. 1 This invention relates to cutting oils and more particularly to improved petroleum base cutting I oils containing stably dissolved sulfur.

Mineral oils containing dissolved sulfur are well known and have been found useful in the metal cutting arts. In the application of these compositions the dissolved sulfur presumably reacts at the hot cutting edge of the cutting tool with the newly machined bright metal surfaces to form a metal sulfide film thereon. This sulfide film surface is effective to prevent adherence of the cuttings and the machined piece to the cutting tool.

However, mineral oils are not good solvents for sulfur, such as flowers of sulfur. The amount soluble varies depending upon the particular mineral oil used and upon the conditions under which the sulfur is dissolved, particularly the temperature of the solution. Dissolved sulfur may be to a substantial degree precipitated from the commonly available sulfur-containing cutting oils by a drop in temperature, for example to about the freezing point of water. Such cutting oils, when subjected to low temperatures while in transit or while in storage, may be seriously damaged because of this sulfur separation. Cutting oils exposed to such conditions generally possess less than 0.7 per cent of elementary sulfur in solution.

It is an object achieved by this invention to provide an improved cutting oil comprising a mineral oil solution of sulfur which is stable at both high and low temperatures. It is a further object achieved by this invention to provide an improved cutting oil composition comprising a stable solution of sulfur in which the dissolved sulfur content is greater than the normal saturation solubility of sulfur in the mineral oil.

Another object of this invention is to produce a cutting oil containing an additive that increases the solubility of sulfur in the mineral oil. Other objects of this invention will be apparent in the body of this disclosure.

I have discovered that when a phosphatide such as lecithin, cephalin, or a mixture of lecithin and cephalin is added to mineral oilhaving an A. S. T. M. aniline point below about 85 6., there occurs a change in the ability of the oil to dissolve and hold in solution added amounts of flowers of sulfur. A greater amount of flowers of sulfur is dissolved by the mineral oil solution containing a phosphatide than can be dissolved by the mineral oil alone at corresponding temperatures, and this increased amount of dissolved sulfur is notprecipitated from the. phosphatidecontaining mineral oil solution even at temperatures as low as 32 F. A mineral oil characterized by having an A. S. T. M. aniline point below about 85 C. and containing as little as about 0.1 per cent of a lecithin-cephalin mixture retains the entire amount of sulfur that is dissolved at temperatures in excess of 250 F. even when held at such low temperaturesas 32 F.

By the term phosphatide as used herein and in the appended claims I mean to include the pure phosphatides such as lecithin and cephalin and mixtures of phosphatides such as the commercially available mixtures of lecithin, cephalin, oil, etc.

The lecithins are phosphatides having the general formula:

I CEO-C0111 In this formula, as in -the case of, the lecithin formula above, the fatty acid constituents R1 may be saturated or unsaturated, as for example,

stearic, palmitic oleic,'and like components. The similarity of the lecithins and the cephalins is evident in their chemical and physical characteristics. Thus both compounds behave similarly toward manysolyents; for example, both are soluble in hydrocarbon-oils but-insoluble in acetone. .Both are waxy in nature and white when pure. Both are easily oxidized on standing in air. The lecithins and the cephalins possess no melting point as both decompose on heating.

Moreover, the various lecithins and cephalins may occur in an alpha or beta form, depending upon the location of the phosphate group in the substituted glycerine molecule. If the phosphate group is present on an end carbon atom, the compound is given the alpha configuration; whereas, if the phosphate is present on the middle carbon atom, the composition has the beta configuration. Lecithins and cephalins, therefore, may occur in either the alpha or beta modification and may vary in composition depending upon the fatty acid tained therein.

I have found that these various lecithins and cephalins and mixtures of lecithins and cephalin's are useful for the purpose of my invention and can be interchangeably used therein, and when referring to lecithins and cephalins andmixtures of lecithins and cephalins herein and in the appended claims, I mean to include alpha and beta lecithins and cephalins and the lecithins and cephalins containing different fatty acid substituents and mixtures of the various lecithins and the various cephalins containing minor amounts of other components such as vegetable oils. Many of the commercially available products sold as lecithin are phosphatide mixtures containing lecithin, cephalin and relatively large amounts of vegetable oils. These mixtures. may be used in my invention without any further purification, but the amount used should be based upon the total phosphatide content of the prodnot. If one so desires, such lecithin-cephalin mixtures containing varying amounts of vegetable oils may be purified by extracting the vegetable oils present therein by means of acetone. Also, separation of the lecithins from the cephalins, if desired, may be efiected by extraction with cold alcohol, since under this condition the lecithins are the more alcohol-soluble constituents. However, for the purpose of my invention, this separation is not necessary, since I have found that lecithinand cephalin, being substituents conphosphatides of a similar chemical nature, areabout equally effective-whether used alone or in admixture in promoting solution of sulfur in the mineral oil compositions. In carrying out my invention, satisfactory results have been obtained with the lecithin-cephalin mixtures in their commercially available'form'known as "Gliddol-R (The Glidden Company,'-'Chicago, 111.). Other commercial lecithin-cephalin mixtures are also usable.

The amount of phosphatide incorporated in the cutting oil according to my invention may be varied substantially. With an amount as low as 0.1 per cent by weight of the oil, a substantial increase in the sulfur-dissolving properties of the composition is obtained. Greater amounts of sulfur will dissolve if larger amounts of phosphatide are used. In general, however, it is not necessary to use more than about 1.5 per cent of phosphatide to obtain as high an amount of stably dissolved sulfur as is usually required for a cutting oil composition. Higher amounts of phosphatide may be used without deleterious eflect. Particularly good .results are obtained with concentrations ofrab'out 0.25 to:1.0 percent of phosphatide by weight; .Within these-concentrations the amount. orstably dissolved-sulfur the presence of phosphatide.

4 may be between about 0.8 and 2.0 per cent at 32 F.

The mineral oils used in the cutting oil compositions of my invention are those having a viscosity within the range of the common lubricating oils with those having a viscosity between about 50 and about 300 S. U. S. at F. being particularly advantageous. My invention is applicable to mineral oils having an A. S. T. M. aniline point below about 85 C. Mineral oils having an aniline point substantially above 85 C., such as mineral white oil having an aniline point of about C., are not improved with respect to their sulfur-dissolving properties by An oil having a viscosity of about 100 S. U. S. at 100 F. and an aniline point of about 75 C. has produced particularly good cutting oil compositions.

In preparing a cutting oil in accordance with my invention, I prefer to mix the mineral oil, the desired amount of sulfur, and the phosphatide in a suitable mixing kettle with heating. Heat is then applied to the contents until a final temperature above the melting point of sulfur is attained. The final temperaure is ordinarily between about 250 and 350 F. The most advantageous temperatures are those of about 280 F. or higher. But the lower temperatures, though less satisfactory because they prolong the time required for the complete solution of the sulfur, are nevertheless operable.

As an example of my invention I have compounded a cutting oil from 1 part flowers of sulfur, 0.50 part by weight of Gliddol-R, the latter containing at least about 50 per cent by weight of a mixture of lecithin-cephalin, and 98.50 parts by weight of a 100/2 Texas oil having a viscosity of 104 S. U. S. at 100 F. and an A. S. T. M. aniline point of 742 C. The oil containing the lecithin-cephalin mixture was digested with the sulfur at about 280 F. until all the sulfur had dissolved, a process usually requiring not more than about five minutes.

On cooling this composition to 32 F., the mineral oil retained all the sulfur in a stably dissolved state. When, however, the same base oil was digested at 280 F. with 1.0 part by weight of flowers of sulfur, but without any phosphatide additive, until all this sulfur had dissolved, a portion of this dissolved-sulfur was precipitated when the solution was cooled to 32 F. This cold solution contained but 0.7part by weight of sulfur. The lecithin-cephalin additive therefore had increased the sulfur content about 0.3 per cent over the amount of sulfur stably dissolved at 32 F. in the mineral oil alone.

In a lathe performance test it was found that the 100/2 Texas oil havinga viscosity of 104 S. U. S. at 100" F. and an A. S. T. M. aniline point of 742 0., when used alone or used in combina-. tion with a lecithin-cephalin mixture, only slightly affected the tool life of the cutting tool. In these cases the tool life was increased from 27 minutes obtained with dry cutting to about 35 minutes and 40 minutes, respectively. In a comparative test, the 100/2 Texas oil contain ing about 0.7 per cent dissolved flowers of sulfur but no lecithin-cephalin mixture gave a tool life of minutes. 0n the other hand, a cutting oil containing 98.5 per cent of the 100/2 Texas oil, 0.5 per cent Gliddol-R (about 50 per cent lecithin and 'cephalin content),- and 1.0 per cent stably dissolved flowers of sulfur exhibited no sulfur'precipitation even on long. standing at 32iand gave a tool life of 640 minutes.

The tool life tests made herein were run on 1020 S. A. E. (Society Automotive Engineers) annealed steel using a high-speed steel (18-4-1) tool of standard contour at a feed of 0.016 inch per revolution, a cut depth of 0.047 inch and at a cutting speed of 200 feet per minute. The results of the tests are outlined in the table.

In order to illustrate the importance of employing a mineral oil having an aniline point below about 85 C., sulfur-containing compositions were prepared from a mineral white oil having a viscosity of 204 S. U. S. at 100 F. and an A. S. T. M. aniline point of l08.5 C. When this oil was digested at 280 F. with 1 per cent by weight of flowers of sulfur, the sulfur readily dissolved, but

upon cooling the resulting solution to 32 F. needle-like crystals were precipitated. When the experiment was repeated using 0.2 per cent of Gliddol-R, needle-like crystals still precipitated on cooling to 32 F. Even when 1.0 per cent of Gliddol-R was employed, the formation of crystals on cooling the solution to 32 F. was not prevented.

This application is a continuation-in-part of my co-pending application, Serial No. 677,535, filed on June 18, 1946, now abandoned.

Having discussed my invention with reference to particular embodiments, it is to be understood that these embodiments are merely by way of illustration and are not limitations of my invention except as hereinafter defined in the appended claims.

1. A petroleum base cutting oil composition consisting essentially of a stable solution of flowers of sulfur and a phosphatide in a mineral oil having an aniline point below about 85 C., said solution containing a greater amount of dissolved sulfur than can be dissolved in the mineral oil in the absence of said phosphatide.

2. A petroleum base cutting oil composition consisting essentially of a stable solution of flowers of sulfur and lecithin in a mineral oil having an aniline point below about 85 C., said solution containing a greater amount of dis--.

6 solved sulfur than can be dissolved in the mineral oil in the absence of said lecithin.

3. A petroleum base cutting oil composition consisting essentially of a stable solution of flowers of sulfur and cephalin in a mineral oil having an aniline point below about C., said solution containing a greater amount of dissolved sulfur than can be dissolved in the mineral oil in the absence of said cephalin.

4. A petroleum base cutting oil composition consisting essentially of a stable solution of flowers of sulfur and a mixture of lecithin and cephalin in a mineral oil having an aniline point below about 85 C., said solution containing a greater amount of dissolved sulfur than can be dissolved in the mineral oil in the absence of said mixture of lecithin and cephalin.

5. A petroleum base cutting oil composition consisting essentially of a stable solution of about 0.8 to about 2.0 per cent by Weight of flowers of sulfur and about 0.1 to about 1.5 per cent by weight of a, mixture of lecithin and cephalin in a mineral oil having an aniline point below about 85 C.

6. The method of preparing a petroleum base cutting oil containing flowers of sulfur stably dissolved therein which comprises heating at between about 250 and about 350 F. a mixture consisting essentially of a major amount of mineral oil having an aniline point below about 85 0., about 0.8 to about 2.0 per cent by weight of flowers of sulfur and about 0.1 to about 1.5 per cent by weight of a phosphatide for a period of minutes suflicient to effect complete solution of the sulfur and insufficient to effect sulfurization of said mineral oil.

7. The method of preparing a petroleum base cutting oil containing flowers of sulfur stably dissolved therein which comprises heating at about 280 F. a mixture consisting essentially of a major amount of mineral oil having an aniline point below about 85 C., and about 0.8 to about 2.0 per cent by weight of flowers of sulfur and about 0.1 to about 1.5 per cent by of a mixture of lecithin and cephalin for a period of minutes sufficient to effect complete solution of the sulfur and insufilcient to effect sulfurization of said mineral oil.

DAYTON P. CLARK, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,138,546 High Nov. 29, 1938 2,159,908 Nill May 23, 1939 2,339,371 Becker Jan. 18, 1944 2,396,345 Rogers et al. Mar. 12, 1946

Claims

1. A PETROLEUM BASE CUTTING OIL COMPOSITION CONSISTING ESSENTIALLY OF A STABLE SOLUTION OF FLOWERS OF SULFUR AND A PHOSPHATIDE IN A MINERAL OIL HAVING AN ANILINE POINT BELOW ABOUT 85* C., SAID SOLUTION CONTAINING A GREATER AMOUNT OF DISSOLVED SULFUR THAN CAN BE DISSOLVED IN THE MINERAL OIL IN THE ABSENCE OF SAID PHOSPHATIDE.