US2483600A - Preparation of high-viscosity extreme pressure base by airblowing - Google Patents

Description

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Patented Oct. 4, 1949 Sulfurization and P 3 treatment of a fatty oil 5 UNITED STATES PATENT OFFICE PREPARATION OF HIGH-VISCOSITY EX- TREME' PRESSURE BASE BY AIR- BLOWING No Drawing. Application May 16, 1946, Serial N0. 670,302

9 Claims. (Cl. 252-465) This invention relates to lubricant additives and to method of preparing same.

In Whittier Patent No. 2,211,306 there is disclosed and claimed a method for making a lubricating stock by sulfurizing and phosphorizing fatty bodies. In accordance with the method there outlined, it is customary to react the materials in open kettles with constant agitation. We have found, however, that when using fatty oils or esters of high-boiling fatty acids which contain a relatively high content of free fatty acid, it is not possible to prepare a sulfurized and phosphorized stock of high viscosity in the manner hereinbefore disclosed.

Sulfurized and phosphorized fatty oils and esters are particularly useful as E. P. additives in connection with Gulf Coast or naphthene base .oils, since the additive is completely soluble in oils of this type, whereas it tends to separate from Pennsylvania base oils. However, Gulf Coast oils have notoriously low viscosity indexes and as a result exhibit low viscosity at elevated temperatures. Lubricating 011 made by blending Gulf Coast mineral lubricating oil with sulfurized and phosphorized fatty oil, made in accordance with Whittier Patent No.'2,211,306, although eminently satisfactory for ordinary use in motor vehicles, will not in general meet the 85 minimum V. I. federal government specification for a universal gear lube (specification 2-105 B).

We have discovered that lubricant additives of high viscosity, which can be blended with Gulf Coast oils to meet government V. II specifications, can be made from fatty oils and ,fr om st e rs o f high;b gil i ng fatty acids and polyhydric alcohols, in general, containing a relatively high, ff'ee acid content by conducting the suhurizaiion operations in t h e presence of finely dispersed air brought into intimate contact with the materials undergoing reaction. Viscosity of the product can be further increased by also conducting the phosphorization step in thepresence of finely dispersed air brought into intimate contact with the materials undergoing reaction.

Our invention is directed to sulfurization and phosphorization of those fatty oils and esters of high-boiling, fatty acids and polyhydric alcohols in general which contain relatively high amounts of free fatty acids, as for example, oils contain- A contaminated with free fatty acids. Oils 0 esters useful in preparing additives in accordance with our invention are those having a fatty acid radical containing a single double bond and from 10 to 24 carbon atoms in the radical in combination with a'polyhydric alcohol such as glycol or glycerin. Mixed esters in which saturated as well as unsaturated fatty acids are present in free or combined form, as for example, a mixture of olein and stearin, are suitable provided the content of highly unsaturated esters, i. e. esters containing more than one double bond, is suiliciently low so that the esters and free fatty acids do not exhibit drying properties. Example s o f oils which aresuitable a elard. tallpwi nsioliye.si I TTERE pl s rsetlei. auitae sasaezsdcdeat and glycerol oleate.

In preparing lubricant additives in accordance with our invention, the fatty oil or ester contaminated with free fatty acid is cooked with elementary sulfur in an amount of approximately 5-9 by weight of the oil or ester at temperatures of approximately 300 to 350 F. for a period of time sufiicient to obtain a good copper strip corrosion test as disclosed in the aforesaid Whittier Patent No. 2,211,306. Reaction is carried out with constant stirring or agitation and in general it has been found that a reaction period of about seven and one-half hours at 330 to 340 F. will give a satisfactory copper strip corrosion test. The copper strip corrosion test indicates whether or not the sulfur has all been chemically combined with the fatty oil or ester. In preparing our product, it is important that substantially no sulfur remain dissolved in the reaction mixture in the uncombined state. It will be understood that the period of reaction may be more or less than seven and one-half hours depending upon the attainment of a good copper strip corrosion test.

In carrying out the processrweprefertomix withthe fatty oil or estera small amount of eral oil of the type with which the finished additive is to belb lended; in order to reduce the -viscosity oijhgtlll fifjfilafid facilitate handling thereof. For this purpose, we have found that approximately 5 to 10 parts by weight of mineral oil per parts of fatty oil or ester is sufficient for this purpose. The fatty oil or ester mixed with the small amount of mineral oil is heated slowly to a temperature above the melting point of sulfur, but below 300 F. and finelydivided flowers of sulfur are slowly added to the heated oil while being agitated. After the sulfur is all added, the temperature of the mixture is then. raised to the desired reaction temperature,

EXAMINE preferably 330340 F., and maintained at this temperature with constant agitation and with intimate contact of air. A suitable method of introducing finely-dispersed air into the mixture undergoing reaction is to attach a porous stone, such as corundum, or fritted glass, to the end of a pipe through which air is forced so that the air leaving the end of the pipe is forced through the interstices in the stone or fritted glass, thereby breaking the air into minute particles in which form it bubbles upwardly through the mixture undergoing reaction. The bubbling of air through the reaction mixture may be continued during the entire cooking period or for only a portion thereof, depending upon the viscosity of the product desired and the rate at which air is forced through the mixture undergoing reaction. By trial, the proper rate for feeding air to a mixture can be determined so that air can be introduced continuously during the entire reaction period and the desired viscosity obtained.

When the viscosity of the sulfurized oil and the copper strip corrosion test are satisfactory, the reaction is discontinued and the mixture allowed to cool to a temperature of approximately 200 F. or lower. Phosphorus in the form of phosphorus sesquisulfide is then added in an amount equivalent to approximately 0.1 to 0.6% by weight of phosphorus based on the sulfurized fatty oil or ester. The mixture is then heated to a reaction temperature of approximately 200- 230 F. with constant agitation until the product when blended with mineral oil to make a finished lubricant gives a satisfactory Timken test. In general, the phosphorization period is approximately five hours. The length of the phosphorization cooking period can be determined by making periodic Timken tests and determnng when the Timken test no longer improves. When the Timken test has reached its maximum value, there is no point in cooking for a longer period of time.

Air blowing of the mixture during the phosphorization period may or may not be practiced,

the entire mixture was violently agitated. The mixture was then slowly heated to a temperature of 285 F. while being agitated, and then 7.4 parts by weight of finely divided flowers of sulfur were slowly added. The addition of the flowers of sulfur took place over a period of onehalf hour and the temperature of the mixture was maintained at approximately 285 F. to 295 F.

After the addition of the flowers of sulfur, the temperature of the mixture was raised to 330 F. Then a porous stone fixed at the end of a tube was immersed deeply into the mixture and measured amounts of air were introduced through the tube and porous stone with a resulting fine and intimate dispersion of air into the base during cooking. The agitation and air-blowing was continued for a period of at least 7 hours while the temperature was maintained at from 330 F. to 340 F. Corrosion tests of the mixture were made from time to time by immersing a polished copper strip therein for one minute. At the end of sulfurization the strip no longer showed a black coating and the cooking and air-blowing of the mixture was discontinued. The sulfurization period gave a peacock corrosion strip which was satisfactory. At this point the mixture was cooled to room temperature.

The sulfurized base was then phosphorized by heating the mixture to approximately 185 F. to 195 F. and adding 0.4% finely divided phosphorus sesqui-sulfide. The mixture was agitated and cooked for 5 hours at 220 F. to 230 F. Airblowing of the mixture was continued during the phosphorization period until the desired viscosity was reached.

A number of samples of sulfurized and phosphorized lard oil additives were prepared in accordance with the process just outlined, with the exception that in some cases no air-blowing was practiced and in other cases the amount of air fed to the reaction mixture differed with different samples. The lard oil used in preparing all depending upon the viscosity of the product sampl'es was a mixture of 1 n 9 Hard oil priortophosphorization. During phosphorization comammg about 15% P3 f 9 free f tty some increase in viscosity takes place, but if the and 1 part Prime lard 011 containing viscosity is not in the vicinity of the finally deabout y Welght of free i y acid- The sired viscosity, air-blowing or intimate contact data Wlth respect 0 e p epa at on of the varwith air, in the same manner as conducted during 1011s a p and the viscosity o he final P dthe sulfurization step, may be continued during uct are given in the following Table I:

Table I Cu.Ft.otAir Introduced Period of Via/210 F. g fg-ggggi Period of Via/210 F. Base N0. by Blowing During Sulfurizaafter Sulfur- Darin 1, how Phosphoriafter Phos- Sulfurization tion ization i ration phorization Hours Hours No Air Blowing 7% 262 No Air Blowing 5 321 11% 317 .do 5 387 cu.it. per hour. 7% 5 431 1 cu. ft. per hour 7% ..do 5 4 2 24 cu. ft. per hour 7% 29 cu. ft. per hon 5 688 17 cu. ft. per hour.. 12% N0 Air Blowing... 5% 708 16 cu. ft. per hour. 7% -d0 5% 732 Quantity Unknown 12 730 Quantity Unknown.-- 5 l, 194

phosphorization until the desired viscosity is ob- The effect of increasing the amount of air blown tained. through the mixture during cooking in increas- The following is an example of the method in ing the viscosity is apparent from the comparison preparing a product in accordance with our inof Bases Nos. 1, 3, 4 and 7. The effect of rapid vention: agitation or stirring as compared to slow stirring To 87.6 parts by weight of lard oil (50% prime is shown by a comparison of Bases Nos. 6 and 7. lard oil and 50% No. 1 lard oil) was added 5 parts In he p eparation of Base No. 6 slow agitation by weight of Gulf Coast lubricating oil of 200 to was used and as a result, in 12% hours the vis- 210 Saybolt Universal viscosity at 100 F. and cosity was slightly less than that obtained in 7 /2 hours in connection with Base No. '7 with a slightly lower rate of air blowing. This more rapid agitation expedites rates of viscosity increase.

In the preparation of Base No. 8, the object was to obtain a certain viscosity and no measurement of the quantity of air blown through the mixture was made. It was not possible to obtain a viscosity as high as '700 seconds Saybolt at 210 F. without air-blowing. Note Base No. 2 in which sulfurization was carried out in 11 hours and phosphorization in 5 hours. The finished material had a viscosity of only 387 seconds Saybolt at 210 F.

Products made in accordance with our invention not only have a higher viscosity than those prepared in the absence of intimate contact with air, but increase the viscosity index of the finished lubricant in which they are blended. Moreover, the finished lubricant containing sulfurized and phosphorized base, prepared in accordance with our invention, produces a finished lubricating oil having a lower pour point than those oils produced from sulfurized and phosphorized bases prepared without air-blowing. The load carrying ability of the finished lubricants made from our additives exhibit excellent Timken tests and give successful results when tested in an automobile. These lubricants also meet the approval of the Army Ordnance Department.

In order todemonstrate the superior viscosity index and pour point characteristics of bases made in accordance with our invention, a series of blends was made containing 18% of sulfurized and phosphorized lard oil base prepared in accordance with the example previously given, except that in some cases no air-blowing was used and in other cases different amounts of airblowing were used. The lubricating oil with which the base was blended was a mixture of Gulf Coast pale oil having a Saybolt Universal viscosity at 100 F. of approximately 200 seconds and a Gulf Coast bright stock having a viscosity of approximately 160 seconds Saybolt at 210 F. The viscosity of the base, viscosity of the finished lubricating oil blend, viscosity index and the pour point of the finished lubricating oil are given in Table II:

has a tendency to separate from the oil. Gulf Coast oils have notoriously low viscosity index characteristics. However, additives made in accordance with our invention raise the viscosity index of the finished lubricant so that the finished lubricant will meet government requirements.

It will be seen, therefore, that by carrying out the sulfurization and the phosphorization of fatty oils and esters of high-boiling fatty acids, and polyhydric alcohols contaminated with substantial quantities of free fatty acids, while intimately contacting the mixture with finely dispersed air, an additive can be prepared having sufficiently high viscosity to impart to mineral lubricating oils a superior viscosity index and pour point.

It is claimed:

1. The method of preparing a high viscosity extreme pressure additive comprising, reacting sulfur with a non-drying fatty oil containing a substantial amount of free fatty acid, at temperatures of approximately 300-350 F. while maintaining said non-drying fatty oil in intimate contact with finely dispersed air, said finely dispersed air being injected rapidly into the reaction mixture by passing air through a solid porous body immersed in the mixture of said oil and sulfur until a good copper corrosion strip test is obtained and then phosphorizing the sulfurized product with phosphorous sesquisulfide at a temperature of approximately 220230 F., and continuing the reaction until a sulfurized and phosphorized product having a viscosity of at least about 700 seconds Saybolt at 210 F. is produced.

2. Method in accordance with claim 1 in which finely dispersed air is intimately contacted with the mixture undergoing reaction during the phosphorization step.

3. The method of preparing a lubricant additive comprising, reacting a non-drying ester of a fatty acid containing from 10 to 24 carbon atoms in the molecule and a polyhydric alcohol, contaminated with at least 5 per cent of free fatty acid, with about 3 to 9 per cent by weight of sulfur at a temperature of approximately 300- 350 F. while intimately contacting the body of the reaction mixture with dispersed air and accomplishing the aeration by forcing air through Table II Vis. 210 F. of Base Used Amount of Air Blowx fig g fig i Pom- Point of iiilallgge mg of the Base Blend Blend Blend Lube Blend F. 387 No air blowing 86. 2 l, 168 75 +10 400 do 88.0 1,220 74 +10 431 34 cu. ft. per hour +10 537 23 cu. ft. per hour".-. 87. 6 1, 105 84 1 683 2:1 cu. per 111mm"... 86. 1 1,026 88 +5 cu. per our. 732 16 cu. ft. per hour 957 1 Two samples combined.

From Table II it is apparent that the last two lubricants listed had a viscosity index in excess of 85 and had a pour point somewhat lower than the lubricating oils made from sulfurized and phosphorized base made without air-blowing.

Bases made in accordance with our invention are particularly useful when blended with Gulf Coast oils for the preparation of extreme pressure lubricants for use in automotive transmissions and differentials. Generally, it is preferred not to use bases made in accordance with our invention in Pennsylvania grade oils, since the base a solid porous body immersed in the mixture of said ester and sulfur, continuing the reaction until the product gives a good copper strip corrosion test and then phosphorizing the resulting product, and continuing the reaction until a sulfurized and phosphorized product having a viscosity of at least about 700 seconds Saybolt at 210 F. is produced.

4. Method in accordance with claim 1 in which the resulting product is phosphorized with a small amount of phosphorus sesquisulfide at temperatures of approximately 220-230" F. while in- 7 timately contacting the mixture with finely dispersed air.

5. Method in accordance with claim 1 in which the resulting product is phosphorized by reacting it at about 220-230 F. with phosphorus sesquisulfide equivalent to approximately 0.1 to 0.6% of phosphorus, based on said product while intimately contacting the reaction mixture with finely dispersed air.

6. Method in accordance with claim 1 in which the fatty oil is No. 1 lard oil.

7. Method in accordance with claim 1 in which the fatty oil is a mixture of prime and No. 1 lard oil.

8. The method of preparing a high viscosity extreme pressure additive comprising cooking a mixture of the following constituents in the following proportions by weight:

No. 1 lard oil 43.8 Prime lard oil 43.8 Gulf Coast lubricating oil 5 Sulfur 7.4

at a temperature of approximately 330-340 F., while intimately contacting the mixture with finely dispersed air, said air being passed into the mixture in dispersed form by forcing it through a solid porous body immersed in the mixture, until the reaction product exhibits a good copper strip corrosion test, then reacting the resulting product with phosphorus sesquisulfide in the proportions of 100 parts by weight of the former to about 0.4 part by weight of the latter, at a temperature of about 220 to 230 F., while intimately contacting the mixture with dispersed air and continuing the reaction until a product is obtained which imparts an optimum Timken test to a finished lubricant containing said product, said product being a sulfurized and phosphorized material having a viscosity of at least 700 seconds Saybolt at 210 F. and being capable of imparting a viscosity index greater than about to a finished lubricant containing said product blended with a low viscosity index Gulf Coast Pale oil in the amount of about 18 per cent.

9. The method of preparing a high viscosity extreme pressure lubricant additive comprising, reacting sulfur with a non-drying oil composed in substantial part of an ester of a polyhydric alcohol and a high boiling fatty acid containing from 10 to 24 carbon atoms per molecule and one double bond in the acid molecule, said oil containing a substantial amount of a free fatty acid, at temperatures in the range from about 300 to 350 F., while aerating said oil with a stream of finely dispersed air created by passing air through a porous body immersed in said mixture and continuing the reaction and aeration until the oil shows a good copper corrosion test,

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

UNITED STATES PATENTS Name Date Whittier Aug. 13, 1940 Number