US2222643A - Sulphurized oil - Google Patents

Description

Patented Nov. 26,1940

- UNITED STATES SULPHUBIZED on.

John 0. Zimmer, Hillside, N. J.,- assignor to Standard Oil Development Compa a corporation of Delaware No Drawing. Application October 8, 1937, Serial No. 168,011

The present invention relates to sulphurized oils and to methods for making the same. The invention will be fully understood from the following description:

It has been known for many years that sulphur increased the load bearing capacity of oils for lubrication of hypoid and other gears where high or extreme pressures may be encountered, metal working and the like and many such oils have 10 been and 'are now used for these purposes. In

some cases mineral oils have been sulphurized directly; in others fatty oils such as lard and fish oils are sulphurized and are added to the mineral bases. Both of these products serve the'purpose 15 but at the same time have many disadvantages; for example, it is difiicult to add enough sulphur to mineral oils to give suflicient load bearing capacity, without encountering sulphur separation when the product is cooled. sulphurized 20 fatty oils containing more than 10 to 12% of sulphur have a very foul odor which is objectionable in cutting oils and the like, and if the sulphur content is reduced the extreme pressure properties are greatly impaired. Moreover their 25 blends in mineral oil do not possess sufilcient extreme pressure properties for satisfactory lubrication of automotive hypoid gears, and the sulphurized fatty oil is often not completely soluble in mineral oil and tends to separate in storage and 30 service.

Similar difficulties occur with the various other sulphurized bases which have been suggested from time to time.

It has now been found that these difliculties it; can be overcome by using as the base to be sulphurized a solvent extraction product of petroleum. The extract is obtained by the use of solventssueh as phenol, cresol, dichlor ethyl ether, aniline, sulphur dioxide, nitro benzol, furfural, and the like, which various solvents with others, too numerous to specifically mention, make up the class of extraction solvents which are used to separate liquid paramnic constituents from non-paraifinic fractions. The extracts may be obtained from petroleum fractions such as.

kerosene, gas oils, and the light and heavy lubricating fractions; The quality of the extract depends of course to some extent upon the crude from which it is obtained and the intensity of 0 the extraction treatment, but for present purposes it has been found that an extract having a viscosity index below about +50 is suitable for the purpose, although it is preferred to use materials having a lower viscosity index, for example be- 5 low 0, -23 or '10. or even lower. The extracts 9 Claims. (01. 252-45) improved may be obtained from paralfinic, naphthenib, or mixed asphaltic base type of crude oils. In general the preferred stocks are those rich in natural sulphur, for example the original sulphur content varies from say 0.6 to 3 or 4% of the extract. 5

The extract may be sulphurized by any of the convenient known methods for introducing free sulphur into the hydrocarbon material; For example, free sulphur itself may be heated with the extract to temperatures of about 325 F., but it is preferred not to raise the temperature in excess of about 375 F. to 400 F. Normal paramnic petroleum oil takes up sulphur with difficulty. It is accomplished only under strong heating and the resulting material is not stable as has been indicated above. The'present stocks prepared from the solvent extraction products of petroleum sulphurize with greater ease at lower temperatures and produce relatively stable stocks of high sulphur content from which the sulphur does not settle on standing.

When the sulphurization is carried out with free sulphur, it is desirable to heat the oil with sulphur to a reaction temperature which'is indicated above as from about 300 F. to 375 F. or 400 F. The reactions occurring are not entirely understood, but it is apparent that the sulphur enters quite readily, but on continued heating for a prolonged time, it is converted into a less active form which is undesirable. Therefore in the present case the oil and sulphur are heated to the reaction temperature for a relatively short period, usually not over two hours and frequently much shorter. Samples are continually withdrawn so that the heating may be discontinued as soon as the sulphur is dissolved and forms a substantially clear solution. When this has occurred, the product should be cooled rapidlg to a temperature below 250 F. in order to prevent further internal reactions which lead to a loss of a portion at least of the extreme pressure capacity. The cooling may be accomplished by circulation of the material through a heat exchanger, but it is preferable to add a part or the whole of the mineral oil with which the base is to be blended in order to bring the temperature down as rapidly as possible below 250. F. It is not necessary to rapidly cool beyond this point.

The product made above is perfectly satisfactory, but its properties may be further improved 60 by a second sulphurization treatment after the initial sulphurized stock has been blended with the petroleum oil in which it is intended to be used. This may be carried out in substantially the same way as indicated above and it is found possible to further sulphurize the product and to markedly increase its already high extreme pressure qualities. As an example of this, say 25% of the total sulphur required in the oil may be introduced directly into sulphurlzation while the balance is used to sulphurize the blend of this extract with the mineral oil in which it is to be used.

Substantially the same results can be obtained in a single sulphurization carried out in the following manner. The solvent extracted oil is blended with a portion of an ordinary mineral lubricating oil, for example, preferably of a parafllnic stock which has a viscosity index above and preferably above 90. The solvent extract may amount to from 5 to 25% of the oil to which it is added and the blend is then sulphurized with the entire quantity of sulphur which is to be used; and which may vary from say 5% of the extract to 25% thereof. The operation is carried out as indicated above, the temperature being reduced rapidly by cooling as for example by the addition of a further quantity of the same or some other similar unextracted petroleum oil or by circulation through a cooler or heat exchanger. The quantities should be such as to leave from about 1 to 5% or more of sulphur on the final product.

While it is preferred to use free or elementary sulphur for the sulphurization treatment, it will be understood that other sulphurizing means which are equivalent may be used for the same purpose.

It has been found that the extraction product referred to above may be used alone as the sulphurized stock, or it may be used to replace a certain amount of the fatty oil which has previously been employed. In some instances, it is .desirable to have some of the fatty oil present and in these cases the extraction product and the fatty oil may either be sulphurized separately and mixed or may be admixed and sulphurized together, for example, in proportion of say 10-75% of the extraction product and -25% of fatty oil such as sperm oil, lard oil, rapeseed oil or the like. The presence of the extraction product appears to greatly increase the ease of sulphurization and to improve the product obtained, particularly from the standpoint of freedom from obnoxious odor and improved load carrying capacity.

The sulphurized stock and the mineral lubricating oil containing the same may be used for many purposes. They may be employed in cutting oils or in oils used for other processes of metal working such as stamping, drawing and the like, wherever, in fact, sulphurized oils are now employed, and the degree of sulphurization of the base and the amount of the base in the mineral oil may vary considerably depending on the particular use to which the oil is to be placed. The stock may also be used for gear lubrication, especially for the lubrication of steel gears operating under high pressures, for example in the automotive differentials or other gear units employing hypoid or other types of gears. For these purposes it is frequently desirable to add to the oil a soluble lead compound such as lead naphthenate or lead sulphonate, or their equivalents. Such materials should be added after the sulphurized stock has been cooled to a temperature of about 175 to 180 F., so as to prevent immediate reaction of the sulphur with the lead, it being desired to obtain the materials in separate compounds in the final oil which is free from suspended solids.

the extract in the initial The oils described and produced as above have excellent extreme pressure qualtities which are not rapidly lost during the normal use of the oil which is one of the chief objections to many of the products now available. These oils show no separation of sulphur and the viscosity index of the finished blend is not so greatly reduced by the use of a sulphurized extract as would be supposed. For example, where an unsulphurized extract is added to a mineral oil of to V. I. in quantity suflicient to give a reduction in viscosity index from 70 to 75, it has been found that after'sulphurization, the same amount of the extract produced a blend of from 85 to 90 V. I. In addition, the compounds are extremely stable during use even when subjected to oxidation. Many of the oils used at the present time oxidize so rapidly as to become solid after a few hours of severe oxidation or in severe high temperature gear service. These oils, however, have been found to thicken only slightly during such treatment.

In order to further illustrate the nature of the present products and the methods by which they are made, the following examples are offered.

Example 1 A solvent extract of a light petroleum lubricating oil was obtained by treatment with-phenol.

Its properties were as follows: v

Gravity A. P. I 15.4 Flash 450 F. Vis. 100 F 1843 Vis. 210 F 83 V. I 5 Pour point 10 Percent sulphur (natural) 1.16 Cast Dark green The solvent extract was heated to a temperature of about 350 F. and 5% by weight of sulphur was added. The temperature was maintained at between 350 and 375 F. for about two hours until a withdrawn sample was found to be substantially clear. The product was then rapidly cooled to 250 F. and a paraflinic cylinder oil was added, about 19 parts of the cylinder oil to 1 of the sulphurized base, and the mixture was then reheated to 350 F. at which time two parts by weight of sulphur were added, and the heating continued as before to effect the reaction.

The final product had a viscosity at 210 F. of 234 seconds Saybolt and a viscosity index of 96. On the S. A. E. testing machine the product carried a scale pull of 580 lbs. on the S. A. E. extreme pressure lubricant tester operated a 1000 R. P. M. at 14.6/1 rubbing ratio and 83.5 lbs/sec. loading rate.

The product was then heated for 18 hours at 200 F. and then tested on the S. A. E. machine at 530 R. P. M. The scale pull was found to be 580 lbs. After 100 hours at 210 F. the test was again repeated using the same machine at a speed of 530 R. P. M. and the product still carried the full load on the test machine.

The above was a very severe test and indicates that the product will not lose its extreme pres.- sure properties even under extreme conditions of operation. On heating for 100 hours at 300 F., it was found that the viscosity had increased from 234 to 275 seconds at'210 F., indicating very little thickening.

Example 2 Two further samples were made up according to the procedure of Example 1 except that in these cases -7 and 10% of the sulphurized extract was used instead of 5%, as in Example 1. Lighter mineral oils were also used so as to give lower viscosities. These materials were: examined When these materials were tested on the S. A. E. machine at 1,000 R. P. M. both showed a scale pull of 580 'lbs. After 18 hours heating at 200 F. the test was repeated at a speed of 530 R. P.-M. and the same scale pull was observed on both samples. After 100 hours heating at 300 F. the samples were again tested on the S. A. E. machine with a velocity of 530 R. P. M. and in each instance the scale pull recorded was 580. After heating for 100 hours at 200 F., the first sample containing the 7% extract had thick"- ened slightly so that its viscosity was now 86.5 seconds. The second sample, however, maintained its original viscosity of 109.2 seconds.

Example 3 In the following tests difl'erent amounts of the solvent extract were used, but in each instance 40% of the unextracted parafflnic mineral oil was added to the extract before sulphurization. The sulphurization was carried out at about 350 F. and as soon as the sulphur was thoroughly dissolved the mixture had been chilled to a temperature below 250 F. The following table shows some of the properties of the materials. Tests 1, 2 and 3 were made on the same mineral oil.

! 1 Q v r i r 1 sampes mac inc a. P. M.

1 Percent extract l l0.. 217 93 580 2 Percent extract 15.. 212 92 580 3 Percent extract 20 192 92 580 4 Percent extract 15 94.5 90 580 5 Percent extract. .20 85.8 86 580 Example 4 In the table below are given inspections and tests on two leaded oils made according to the preferred procedure.

Grade 8. A. E. 90 S. A. E. 160 Type 15% phenol extract 15% phenol extract Gravity, A. P. I 19.0 18.7 Flash F 415 425 475 4590 212 92.0 25 1.97 Sediment, pcrcent Trace 0.1 Sulphur,-percent 2.3 2.4- Sulphur separation at 0 F Nil Nil Almen shock load 15 weights 15 weights S. A. E. machine test (1000 R. P. M.) scale pull 630 lbs. 580lbs.

The above materials were made by blending 15 parts of phenol extract with about 35 parts of mineral oil. The mixture was heated to 250 F. during agitation. and 2.25 parts of S111- phur were added. The temperature was then raised to 350-375 F. during the course of two hours and at the end of this heating period it was found that the sulphur had dissolved into and permanently reacted with the 011. At this point 40 parts of cold mineral oil were then added and the temperature immediately dropped to about 250 F. The product was then further cooled to about 180 when of lead naphthenate and about 1% of a pour point inhibitor were added i Example 5 To illustrate the application of the base stock to cuttingoils and to further illustrate the improvement, experiments were carried out in which lard oil, sulphur and the extraction product of petroleum were heated together to effect sulphurization at a maximum temperature of 370 to 375 F. Different amounts of sulphur were added but it was only required to hold'the material at the temperature for about minutes, to eflect sulphurization. They were then cooled to below 250 F. It was found that when the lard oil was used alone with more than 12% sulphur the odor was very bad, and although the products were blown with air to remove sulphur and sulphite fumes, it was found thatthe odor rapidly developed again. This odor could not be masked by addition of pine oil or other available aromatic materials. When equal quantities of lard oil and phenol extract were used, it was found that considerable more than 15% of sulphur could be introduced easily according to the procedures of the present invention, and while the odor could not be described as pleasant, it was much better than the sample made from lard oil alone and was easily maskedby the addition of small amounts of pine oil, for example, about-1%. The product, whether the pine oil beused or not, is sulphur stable and does not show any separation when stored at zero for'l days. It will be understood that the sulphur is,,of course, in a highly corrosive form and shows high extreme pressure properties. v

The expression, "monohydric phenol extract, is intended to denote an extract prepared by solvent treating the desired petroleum fractions with aromatic compounds containing, attached directly to their nuclear carbon atoms, only one hydroxyl group per molecule. Specifically, the expression is intended to include the use 'of phenol, the cresols, etc.

The present invention is not to be limited by any theory of the mechanism of the present sulphurization process nor to the use of any particular ingredients, but only to the following claims in which it is desired to claim all novelty inherent in the invention.

I claim: p

1. A composition of matter comprising a sulphurized monohydrlc phenol extract of a mineral lubricating oil fraction, said sulphurized extract being prepared by subjecting the monohydric phenol extract to the action of elemental sulphur in an amount between about 1% and about 10% by weight at a temperature between about 300 F. and 375 F., followed by rapid'cooling to below 250 F.

2. A process which comprises sulphurizing a monohydric phenol extract of amineral lubricating oil fraction with elemental sulphur in an amount between about 1% and about 10% by 5 weight at a temperature'between about 300 F. and 3'75 F., followed by rapid cooling to below 250 F.

3. A composition 01' matter comprising a sulphurized monohydric phenol extract of a mineral lubricating oil fraction, the untreatedextract having an A. P. I. gravity above 9, a viscosity index between about +100 and about +50, and having a viscosity at 100 F. of between about 1,000 and about 5,000 Saybolt seconds, said sulhurized extract being prepared by subjecting the monohydric phenol extract to the action oi elemental sulphur in an amount of between about 1% and about 10% by weight at a temperature between about 300 F. and about 375 F., followed by rapid cooling to below 250 F.

47 A process which comprises sulphurizing a monohydric phenol extract of a mineral lubricating oil fraction having an A. P. I. gravity above 9, a viscosity index between about 100 and about +50 and a viscosity at 100 F. between about 1,000 and about 5,000 Saybolt seconds, with elemental sulphur in an amount between about 1% and 10% by weight at a temperature between about 300 F. and about 375"F followed by rapid cooling to below 250 F.

5. A composition of-matter comprising between about 5 and about 25 parts of a sulphurized monohydric phenol extract of a mineral lubricating oil fraction, said untreated monohydric:

phenol extract having an A. P. I. gravity above 9. a viscosity index between about -100 and about and having a viscosity at 100 F. beiwicll about 1,000 and about 5,000 Saybolt seconds, said sulphurized monohydric phenol ex- 0 tract being prepared by subjecting st 1 untreated extract to the action of elemental sulphur in an amount betweenabout 1% and about 10% by weight at a temperature between about 300' F. and about 375 F., followed by rapid cooling to below 250 F., adding between about and about parts 0! a mineral lubricating oil containing 5 at least a small portion of unsaturated compounds and subjecting the resulting mixture to sulphurization with elemental sulphur in an amount of between about 1% and about 5% by weight at a temperature between about 300' F. 10 and about 375 F., iollowedby rapid cooling to below 250 F.

6. A sulphunzed mixture comprising between about 5 and about 25 parts of a monohydric phenol extract of a mineral lubricating oil Irac- 1 tion having an A. P. L gravity above 9, a viscoslty index between about -100 and about +50 and having a viscosity at 100 F. of between about 1000 and about 5000 Saybolt seconds and between about 75 and about parts of a min- 20 eral oil fraction, said mixture being sulphurized by the action of an elemental sulphur in an amount of between about 1 and about 10% by weight at a temperature between about 300 and I about 375 F. iollowed by rapid cooling to below 250 F. E

7. A composition of matter as in claim 6 to which has been a fatty oil prior to the sulphuriion.

8. A composition of matter as in claim 6 to 30 which has been added a small amount 01 a pour point depressant and a soluble lead soap taken from the group consisting of lead naphthenate and lead sulphonate.

9. A composition oi! matter as in claim 6 to 35 which is added between about 3 and about 15% of a soluble lead soap selected from the group consisting oi lead naphthenate and lead sulphonate.

JOHN C. ZIMMER. 40