US2031227A

US2031227A - Lubricating oils

Info

Publication number: US2031227A
Application number: US740786A
Authority: US
Inventors: Ernest F Pevere; Clifford G Ludeman
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1934-08-21
Filing date: 1934-08-21
Publication date: 1936-02-18
Anticipated expiration: 1953-02-18

Description

Patented Feb. 18, 1936 UNITED STATES PATENT OFFlCE LUBRICATING OILS tion of Delaware No Drawing. Application August 21, 1934, Serial No. 740,786

17 Claims.

This invention relates to the manufacture of lubricating oil characterized by a low pour test and/or an increased viscosity index.

The invention contemplates the preparation of mineral lubricating oil having a reduced pour test and other desirable qualities from lubricating oil stock, such as those derived from mixed base and parafiin base crudes and the like, by the addition to the lubricatingoil of a pour point depressant material.

contemplates the addition to a lubricating oil of a small proportion of an esterified hydroxy stearic acid.

The invention also contemplates the preparation of mineral lubricating oil having an increased viscosity index from naphthene base crudes as well as mixed base and paraflin base crudes, by the addition to the lubricating oil of a minor proportion of an esterified hydroxy stearic acid.

Lubricating oil stocks derived fromparaflin and mixed base crudes contain appreciable amounts of wax and, therefore, have arelatively high pour test unless a substantial amount of this wax is is, there is a relatively smallchange inthe viscosremoved. The removal of this wax is usually ac-- .complished by cold settling, filtration or centrifuging. However, lubricating oil stocks, after dewaxing by these processes, may still retain some wax, and may have a pour test abov'e 15 F. and up to about F. The removal of further quantities of wax from these stocks in order to further reduce the pour test necessitates expensive further' processing.

On the other hand, the presence of a certain amount of wax in a lubricating oil may be paratively fiat temperature-viscosity curve. That ity of the oil between temperatures of say 100 V F. and 210 F. Consequently, it is of advantage employed.

to add to the oil a material which will have the effect of reducing the pour test or cold test to the desired extent without the necessity of entirely removing the remaining wax.

We have discovered that the esterification product of a hydroxy stearic acid with a fatty acid constitutes an effective material for additon to a partially dewaxed mineral lubricating oil of this character to lower the pour point thereof. The hydroxy stearic acid may be esterified with a higher fatty acid, such as stearic, palmitic and the like. Very satisfactory results have been secured by esterifying dihydroxy stearic acid with stearic acid. However, similar esterification products of mono-hydroxy stearic acid can be The invention particularly the free fatty acid content had dropped to 3%.

As a specific example of the present invention, the product obtained by esterifying dihydroxy stearic acid with stearic acid is described. The dihydroxy stearic acid may be conveniently obtained by oxidation of oleic acid. For example, a water solution of 84 g. of oleic acid in 1500 cc. of water, to which was added 33 g. of potassium hydroxide, was cooled to around 0 C.; and then a previously prepared solution containing 84 g. of potassium permanganate dissolved in 1500 cc. 1 of water was added slowly with agitation, such that the temperature did not rise above 10 C. The mixture was stirred for an hour after the solution had been added, and then was allowed to stand for a period of time. The precipitate 1 of manganese dioxide was filtered off and the solution acidified with dilute sulphuric acid, which caused the precipitation of the dihydroxy stearic acid. This was filtered, dried, extracted with ether and again dried.

20 g. of the dihydroxy stearic acid was then heated with 16.8 g. of commercial stearic acid to a temperature of around 240 C. while under high vacuum equivalent to about 20 mm. Hg. The temperature was maintained at 240 C. for 2 hours. The product was then found to contain about 5% free fatty acid (figured as stearic acid). It was again heated to 240 C. and maintained at this temperature for an hour, at which time After cooling, the reaction product was dissolved in about 300 cc. of diethyl ether, filtered, and the filtered ethereal solution washed first with sodium carbonate solution and then with distilled water. The ether was then evaporated and the product heated at 110 C. for 1 day, and then cooled over calcium chloride.

The substance so obtained is a light amber colored elastic jelly; and apparently is a complex portions of about 0.25-l.5 by weight. The reaction product is preferably added to the -oil by heating therewith at a temperature of around 100 C., and then filtering to remove the insoluble portion. The following results were obtained when this reaction product was added to a partially dewaxed paraflin base lubricating oil having a pour point of +20 F.

Pour, F. 100 cc. oil-Hess than 0.25 g. esterification product 0, -5 100 cc. oil+less than 0.5 g. esterification product -15, --10 100 cc. oil+less than 1.0 g. esterification product -30,

In the production of high grade lubricating oils, it is well known that a relatively small change in the viscosity of the oil between temperatures of say 100 F. and 210 F., is desirable. In other words, it is advantageous for the oil to have a relatively flat viscosity-temperature curve, which means that the oil has a high viscosity index as defined by Dean and Davis in their article in Chemical and Metallurgical Engineering, Vol. 36, page 618. Improvement in lubricating oils has heretofore been accomplished by refining, as by the use of selective solvents which are efiective in extracting or separating naphthenic constituents from paraflinic constituents, thereby producing a resulting raflinate of increased viscosity index. This procedure involves expensive processing, and results in a reduced yield of finished oil.

The addition of an esterified hydroxy 'stearic acid of the character described above-in controlled proportions to a naphthene base or paraflin base lubricating oil is also found to materially increase the viscosity index thereof. When the esterification product is added to improve the viscosity index of a lubricating oil, a proportion of about 545% by weight is generally employed.

The following results were obtained by the addition of the mentioned amounts of the esterification product of dihydroxy stearic acid with stearic acid to naphthene base lubricating oils:

Weight in grams of Saybolt Saybolt Vol. ol oil inc.e. eotcriflcation vllcosit viscosit Viscosity product atiqf at 210 index added In the above examples, a substantial proportion of the esteriflcation product added to the.

mineral oil was not dissolved, and was filtered out before testing. Consequently, the actual proportion of viscosity index improver dissolved is substantially-less than the amount indicated in the above table.

Where the expression paraflin base lubricating oil" is used in the accompanying description and claims, it is to be understood that this refers to an oil of the mixed base or mid-continent type as well as an oil of the paraflin base or Pennsylzeantia type, unless the contrary appears from the We are aware that it has heretofore been proposed to add hydroxy stearic acid, or the zinc or magnesium salts thereof, to a mineral lubrieating oil as a pour point depressant. The present invention is distinguished by the use of a substantially neutral esterification product of the hydroxy stearic acid, thereby avoiding objections inherent in the use of free acids or metal salts in an oil, particularly when adapted for use as 2 motor oil, while at the same time securing increased efiectiveness and other advantages.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating oil of improved character comprising a mixture of a petroleum lubricating oil with a minor proportion of an esterified hydroxy stearic acid.

2. A lubricating oil of improved character comprising a mixture of a petroleum lubricating oil with a minor proportion of an esterified dihydroxy stearic acid.

3. A lubricating oil of improved character comprising a mixture of a petroleum lubricating oil with a minor proportion of the esteriflcation product of a hydroxy stearic acid with a fatty acid.

4. A lubricating oil of improved character comprising a mixture of a petroleum lubricating oil with a minor proportion of the esterification product of a hydroxy stearic acid with a higher fatty acid.

5. A lubricating oil of improved character comprising a mixture of a petroleum lubricating oil with a minor proportion of the esterification product of a hydroxy stearic acid with stearic acid.

6. A lubricating oil of improved character comprising a mixture of a petroleum lubricating oil with a minor proportion of the esterification product of a dihydroxy stearic acid with stearic acid.

'7. A lubricating oil having a pour point of about 0 F. or below, comprising a partially dewaxed paraffin base petroleum lubricating oil mixed with about 0.25-1.5% by weight of an esterified hydroxy stearic acid.

8. A lubricating oil having a pour point of about 0 F. or below, comprising a partially dewaxed base petroleum lubricating oil mixed with about 025-1.5% by weight of the esterification product of dihydroxy stearic acid with stearl'c acid.

9. A lubricating oil of improved viscosity index, comprising a petroleum lubricating oil admixed with about 515% by weight of an esterified hydroxy stearic acid.

10. A lubricating oil of improved viscosity index, comprising a petroleum lubricating oil admixed with about 515% by weight of the esteriflcation product of dihydroxy stearic acid with stearic acid.

11. A pour point depressant material and viscosity index improver for a mineral lubricating 011 comprising an esterified hydroxy stearic acid.

12. A pour point depressant material and viscosity index improver for a mineral lubricating oil comprising the esteriflcation product of a hydroxy stearic acid with a higher fatty acid.

13. A pour point depressant material andviscosity index improver for a mineral lubricatin oil comprising the esteriflcation product of dihydroxy stearic acid with stearic acid.

14. The method of improving a mineral lubricating oil, which comprises esterifying a hydroxy stearic acid, and dissolving the esterified product 11111 a minor proportion in a mineral lubricating o 15. The method of improving a mineral lubrieating oil. which comprises reacting a hydroxy stearic acid with a higher fatty acid to produce an esterified hydroxy stearic acid and dissolving the esterified product in a minor proportion in a mineral lubricating oil.

16. The method of improving a mineral lubrieating oil, which comprises reacting hydroxy stearic acid with stearic acid to esterify the former, and dissolving the esterified product in a minor proportion in a mineral lubricating oil.

17. The method of improving a mineral lubricating oil, which comprises oxidizing oleic acid to dihydroxy stearic acid, esterifying the dihydroxy stearic acid with stearic acid, heating the esterifled product with a. mineral lubricating oil, and filtering the resultant oil to remove undissolved residue.

ERNEST F. PEVERE. CLIFFORD G. LUDEMAN.