US2172285A - Sulphurized oil - Google Patents

Description

Patented Sept. 5, 1939 um'rso I sraras SULPHURIZED OIL Bert E. Lincoln and Waldo L. Steiner, Ponca 'City', Okla., assignors to Continental Oil Company, Ponca City, Okla, a' corporation of Delaware No Drawing.

Application February 14, 1935,

Serial N0. 6,488

' 3 Claims.

Our invention relates to sulphurized oils and new compositions of matter used in the preparation thereof.

It has long beenknown that sulphur com- 1. pounds when added to lubricating oils impart certain properties tothe mixtures which are of great value when these mixtures are used as lubricants for very heavy duty such as is encountered in the lubrication of automotive gears of m the hypoid and spiral bevel types and other power transmission gears and for the lubrication of cutting tools such as are used in cutting and threadlngsteel pipe. The exact manner in which the sulphur compounds act to produce 5 these results is not known with any degree of certainty. However, it is not merely a matter of the increased film. strength which sulphur compounds impart to lubricating oils since for each sulphur compound that may be added to a lubricating oil to increase its film strength, there is an optimum percentage above which there is no tendency to obtain further increase with greater percentages of the sulphur compound. On the other hand there seems to be no limit to v the improvement of a cutting oil that can be obtained by increasing its sulphur content. at least,

as far as the smoothness oi. the metal cut ob-- tained with it is concerned.

All sulphur compounds do not have this bene- 0 ficial effect on lubricants to the same degree as will be brought out in the examples given and to most of those now in use there are certain deflnite objections.

pounds used for blending with lubricating oils are the sulphuretted glycerides of the unsaturated fatty acids. .These will usually contain about twelve percent J sulphur. sulphuretted lard oil is a typical example. These compounds are not entirely satisfactory for blending purposes for several reasons. They are very viscous and hard to handle. raise the pour point of the oil with which they are blended, ha'vea very strong odor of hydrogen sulphide, are irritating to the skin of the operators working with them, are not very stable when in use and do not give a good metal cut when used in a cutting lubricant or a very high mm strength when used in an extreme pressure lubricant.

Even with using a large percentage of these sulphur base oils, cutting lubricants are obtained which are rather inefllcient as far as cutting qualities are concerned, objectionable on ycount of odor, irritating to the skin particularly on the knees and elbows of the operator and in case of slight cuts on the hand very liable to cause sores The most common sulphur com-' which are slow to heal, are very viscous when cold, are not stable to heat while in use and. as a. result break down and thin out. It is mainly due to this fact that the sulphuretted glycerides are ineflicient sulphur bases for the prepara- 5 tlon of cutting oils. This breaking down results from the excessively high temperature developed in the restricted areas surrounding the cutting tools. This hightemperatureis the cause of the decomposition of some of the glyceride, which liberates products which have a very irritating eifect on the skin. Most of th e irritating products come from the decomposit on of the glycerine in the sulphur base. It i'sthereiore desirable that a. sulphur base should be used which does 16 not contain any glyceride or glycerine. Furthermore some cracking oi! the petroleum base also takes place in this high temperature zone, giving products which dilute the oil and lessen its efliciency.

An extreme pressure lubricant for gears which is made from the conventional sulphuretted glycerides. such as for example lard oil, has many defects. The film strength is not very high, the pour point of the lubricant is raised 5 degrees to 25 degrees F., depending upon thetype oi petroleum base oil used, and the oiliness characteristics are not as satisfactory as desired. The glyceride breaks down releasing glycerine which tends to undergo changes resulting in a go gum-like deposit which is objectionable in a high quality cutting oil or extreme pressure lubricant.

One object of our invention is to prepare sulphurized oil providing a cutting oil or a lubricant having a high illm strength.

Another object of our invention is to provide a sulphurized oil which is stable and devoid oi obnoxious odor.

Other and further objects of ourinvention will appear from the following description We have discovered that the sulphuretted organic acids make an excellent sulphur base for blending with lubricants for preparing superior cutting oils and gear lubricants. They-are supe- I rior to the conventional sulphuretted glycerides 5 of unsaturated fatty acids ina number of ways. v To begin with they are in general much less viscous even when containinga much larger per centage of sulphur and are therefore easier to handle. They may be easily and permanently 5 freed from the 'odor of hydrogensulphide by blowing for a few minutes with sulphurdioxide after sulphu'retting. They are as a group much more stable to heat when used in cutting oils than the sulphuretted glycerides and conses5 soluble in petroleum lubricants than the sulphjur etted glycerides. The latter have a marked tendency on standing to show sludge-like deposits on the bottom of the containers in which blends of this base and petroleum lubricants have been stored. Lastly, the pour point of blends made with a petroleum lubricant is higher by degrees to 42 degrees F. (depending on the type of lubricant) when a sulphuretted glyceride is used than when a sulphuretted organic acid is used.

The viscosity of the sulphuretted glyceride blends is very much higher at temperatures from 0 degrees to 50 degrees F. than the same blends where the sulphuretted acids of the same glycerides are used. This is 'a very important consideration for either a cutting oil or a power transmission gear lubricant. In the case of the former it is frequently difilcult to obtain a good flow of the cutting oil from the sump of the machines on cold mornings in a shop that is not too-well heated. Under these conditions the machines do poor work and the cutting tools are dulled.

The disadvantages of a relatively high pour test and high viscosity at cold weather temperatures in the case of gear lubricants causes excess loss of power in overcoming the internal friction -of the lubricant and difllculty in shifting of gears in the case of automobile transmission gears.

A number of examples of the sulphuretted organicacid type of blends of lubricants used for cutting oils and gear lubricants will be described. Similar blends containing the same amount of added sulphur but made with a sulphuretted glyceride of an unsaturated fatty acid will also be described. The superior results of the tests on the former blends will demonstrate the improvement obtained by the use of these sulphur bases over the well-known sulphuretted glycer-- ides.

The method of testing and comparing the emciency of the cutting oils in question consisted in the use of a 2" Toledo thread cutting machine under a set of standard commercial operating conditions with the diiferent oils and comparing the threads obtained with each. The smoothness of the ridges and the tearing or lack of tearing in the troughs was noted and the cutting oil graded accordingly. Note was also made of the odor of the cutting oils, since a cutting oil might be quite efllcient as a lubricant but have such an obnoxious odor that .it could not be used. The comparative cooling properties of the different oils was also noted by observing the tendency of the oil to smoke while in use and also by the temperature of the nipple that had been threaded. This heating and smoking tendency of the oil is directly related to the vetliciency of the lubricant as it has been noticed that the more heating and smoking that accompanies the cutting, the poorer will be the ilnished thread.

The method of testing the new sulphur bases to determine the relative value they possessed as extreme pressure compounds compared to the sulphuretted glycerides, consisted in making blends with a heavy petroleum lubricating oil in which the same quantity of added sulphur was used in each and determining the fllm strengths of these blends on the Timken machine. This is a device which was developed by the Timken Roller Bearing Co. for comparing film strengths of extreme gives an excellent cutting on which is far superiorwith respect to smoothness of thread obtained, to a similar blend in which sulphuretted lard oil is used in the same proportion and has the iur-' ther advantage of being practically odorless whereas the sulphuretted lard oil blend has a very obnoxious odor. The thread obtained with the former blend is very smooth and shows no tearing while the thread obtained with the latter blend is decidedly rough.

Example #2.-A mixture of organic acids obtained as a by-product from pine wood and which consists of roughly 30% rosin acids, 50% of unsaturated fatty acids, and sterols is heated to 375 degrees F. and sufficient sulphur is slowly added with stirring so that the resulting compound contains at least sulphur. A blend of 8% of this sulphur base, which is equivalent to 2% .of sulphur, with a low viscosity petroleum lubricating oil such as 100 S. S. U. at 100 degrees F. black oilgives an excellent cutting oil while a blend containing 16% of this sulphur base, which is equivalent to 4% sulphur, gives a very superior cutting oil. If a blend containing 20% to 25% of this sulphur base, which is equivalent to 5% to 6 4% sulphur, is made with a lubricating oil, a cutting oilis obtained that gives a far smoother thread when used on a thread cutting machine than the most expensive and best commercial cutting oils now available.

A blend prepared by mixing 13.parts of this sulphur base and 87 parts .of the above mentioned black oil was used in a 2" Toledo thread cutting machine for three months. This is a thread cutting machine in which about 3 gallons of the cutting lubricant is poured into a sump from where it is pumped over the cutting tools and then is allowed to run back into the sump and is thus used indefinitely. After three months use during which time over 1,000 threads were cut and only enough fresh oil was added to make up for what was lost by mechanical causes, a sample of the cutting oil was removed from the machine and tested The sulphur content of the original was 3.7% and of the used oil, 3.3%. The viscosity of the original was 184 S. S. U. at 100 degrees F. The viscosity of the used oil was 186 S. S. U. at 100 degrees F. A thread cut with the used oil was-smoother than a thread cut with a fresh sample of the best commercial cutting oil available to the market. This shows the remarkable stability of this new oil. The life of the cutting The pour point of this new oil is below -15 degrees'F., while the pour point on a similar blend where sulphuretted lard oil is used in the same proportion is +10 degrees F. The odor of the new cutting oil was much less objectionable than the odor of the sulphuretted lard oil cutting 7 lubricant.

26% sulphur was contained. A blend of this sulphur base and 100 S. S U. at 100 degrees F. black oil in which sufficient of. the sulphur base.

" is used to, give 1% up to 6% of added sulphur in the finished-blend has the properties of an excellent cutting oil. Rosin, itself, which is mainly abieticacid, may be sulphuretted and used as a sulphur base for preparing cutting oils; however,

it is not so desirable because a. portion of the sulphuretted rosin is not very soluble in petroleum oil.

A very excellent extreme pressure lubricant may be prepared from any ofthe above mentioned sulphur bases which in comparison with other sulphur bases are much superior in regard to film strength.

Example #4.-A blend consisting of 7% of sulphuretted pine wood acids of- Example #2, which is equivalent to 1.6% of added sulphur, with 83% of steam refined cylinder stock and 10% of a 200 S. S. U. viscosity at 100 degrees F. 1

neutral oil yields a mixture of 14(l S. S. U. viscosity at 210 degrees F. which is a very superior transmission and differential gear lubricant. Its

The saturated organic acids which can be heated to 400 degrees F. without decomposition may be sulphuretted and usedin this invention but are generally not as satisfactory as the un-- saturated organic acids, Some stearic acid was made to take up 12% sulphur by sulphurettin at 400 degrees to 425 degrees F. and a cutting oil prepared as in Examples 1 to 3 which on testing v blends of 'sulphuret'ted, unsaturated fatty acids.

gave a fair thread, but this particular sulphur base raised the pour test, making the. blend less satisfactory foriuse' in a cutting oil than the We feel reasonably sure that the extraordinarily fine results, obtained with the sulphuretted pine wood acid blends o1. cuttings oils, are largely due to the fact that it is possible to incorporate a relatively large quantity or sulphur in these.

types of organic acids. We believe that it is the last 25% or the .sulphur added to these acids which, combined withthe oilines's feature imparted by the carboxyl group of the acids, contributes mainly to the effectiveness ofthis sulphur base for the preparation of cutting oils.- 00

This is'because the sulphur that is added to a compound near, its saturation point is less firmly held than that whichis first taken up. The sulphui' that is looslyheld appears to be'the eflective part of a cutting lubricant.

In sulphuretting, we find thatit'is best toemploy a temperature between 340". I and 400. F. Between this temperature range, we are enabled to obtain the maximum percentage of sulphur. It is to be remembered, of course, that the sulphuretting'action may take place at other temperatures but the best resultsare obtained bev tween the temperature range above specified.

' In preparing a sulphur base for a gear lubricant from'this type of organic base, a more satisfactory pgoduct isobtained if somewhat less than The same viscosity blend theamount of sulphur required tosaturate the organic base is used as this will reduce its corrosiveness.

Some highly unsaturated fatty acids such as for instance those "which are obtainedfrom fish oils cannot be readily sulphuretted so that an oil soluble derivative is obtained, but if these fatty acids are first partially hydrogenated, a very satisfactory sulphur base for cutting oils may be made 'from' them.

- Any means of removing hydrogen sulphide from the sulphur bases after sulphuretting may be employed. This may require theuse of a weak oxidizing or reducing agent or treatment. with gaseous sulphur dioxide or any other means that gives satisfactory results. The means for the removal of hydrogen sulphide from the sulphur bases, however, are not a part of this invention.

While no specific limit to the percentage of the" sulphur base to. be used in preparing the different lubricants referred to in the examples has been drawn, it may be 'statedthat in preparing a cutting oil to be used without first ,diluting, not less than 1% or more than 4% of added sulphur, in the form of the sulphur base in question, is required. If a cutting oil concentrate is-prepared that is to be diluted before use, a. much higher percentage of sulphur may be used in the.

blend. The straight sulphurettedorganic acid may be used also for thispurposef In the case of preparing a lubricant for heavy duty gears as little as .5% of added sulphur may be used for the mild extreme pressure lubricant up to 2.5% of added sulphur for the more rugged extreme pressure lubricant, More is seldom necessary.

A small quantity such as .l% to 2% of sulphur in the form'of one of these sulphur bases may be addedto a crank case lubricant to improve the film strength and oiliness of these lubricants.-

The above ratios of sulphur base to petroleum oil fordts different uses are. not intended to limit the scope of this invention since smaller or larger quantities may. be used in any case with results which are partially satisfactory. They are given because generally Speaking the optimum results limits that are suggested.

ing withthe sulphuretted organic acid bases for the preparation of the various sulphuretted lubricants are not to be limited to the hydrocarbon oils cited in the examples but are to include any hydrocarbonoil of any'type or viscosity such-as may be required by the lubricant in question.

Having'thus described our invention, what-we claim is:

can be obtained by the use ofratios within the The hydrocarbon oils which are used in blend- I 1. A lubricant which is corrosive to the copperv strip test comprising in combination a hydrocarbon oil and a base" prepared by sulphurizifig unsaturated fattyacid obtained from wood oil. I

2. A lubricant including in combination'a hydrocarbon oil and from 1 to 4 per cent of a sulphurizedorganic acid obtained as a by-product from wood, said sulphurized organic acid containing at least 25 per cent of sulphur in chem- .ical combination.

'3. A lubricant including in combination a hydrocarbon oil 'and'from 1 to 4 per cent of a sulphurizedorganic acid. obtained as a .by-

product from pine wood, said sulphurized organicacid containing at least 25 per cent of sulphur in