US2382121A - Lubricant and method of preparing same - Google Patents

Description

Patented Aug. 14, 1945 LUBRICANT AND METHOD OF PREPARING A SAME William A. Whittier, Glenview, m., assignor to The Pure Oil Company, Chicago, III., a corporation of Ohio No Drawing. Application October 17, 1942, Serial No. 462,408

11 Claims.

This invention relates to lubricants and to lubricant additives, particularly those additives which have the ability to impart to mineral lubricating oils the ability to function satisfactorily under extreme pressure conditions and the ability to inhibit metal bearing corrosion. More specifically, the present invention constitutes an improvement over the lubricant additive and the method of preparing disclosed and claimed in Whittier et al. Patent 2,211,306.

I have discovered that the lubricant additive disclosed in the aforesaid patent can be improved upon both as to its load carrying characteristics and as to its viscosity by processing the additive in an oxygen free atmosphere. Although I have found that the greatest improvement in load carrying ability and viscosity of the additive occurs if the sulfurizing step is carried out in an atmosphere free from oxygen, the viscosity of the product is further improved if the phosphorizing step is also carried out in an oxygen free atmosphere, although the load carrying characteristics of the additive do not appear to be detrimentally affected by phopshorlzing in an atmosphere of air.

Heretofore it has been the practice to prepare the additive in accordance with the aforesaid patent by sulfurizing and phosphorizing in open kettles in which the mixture had free access to the air. Under these conditions the viscosity of the resulting additive was relatively high, thereby making the viscosity of the final blend of oil and additive high because of the comparatively large amount of base (18% by volume) which it was required to add to the lubricating oil to obtain the desired load carrying characteristics. By carrying out the sulfurizing step in a closed autoclave from which air is excluded under superatmospheric pressure, it is possible to obtain an additive with a viscosity of slightly above 200 to less than 400 seconds Saybolt Universal at 210 F. as compared to viscosities well above 600 when the additive is made in the presence of air. Moreover, the additive prepared in accordance with this invention may be used in far less quantity in the oil blend in order to give the same or superior load carrying characteristics.

In order to demonstrate my invention, a large number of samples of sulfurized and phosphorized additives were prepared under different conditions. In all cases in preparing the additive the following procedure was followed: 2177.5 grams of prime lard oil were mixed with 125 grams of light mineral oil and 12.5 grams of sulfur monochloride and stirred until a homogeneous mixture was obtained. The mineral oil used in this mixture was a Gulf Coast lubricating oil having the following characteristics:

To the mixture was added 185 grams of flowers of sulfur. The sulfur was sifted into the mixture while the mixture was constantly stirred. when all the sulfur had been added to the mixture it was charged into a one gallon autoclave fitted with a stirrer. The autoclave was then flushed with nitrogen to expel any air present and was then sealed. Nitrogen or hydrogen sulfide pressure was maintained above the mixture in the autoclave. In certain experiments the autoclave was left open in order to compare the effect of air with inert gas in the processing of the additive. The autoclave was maintained at a temperature of 330 to 340 F., and in some cases at 360 F., for either 3 /2 or 7% hours and was agitated during the entire time. The product was then pumped from the autoclave and cooled.

The sulfurized product prepared in the foregoing manner was tested for copper strip corrosion, viscosity and load carrying ability. In the majority of samples the sulfurized oil made, as just described, was further treated by mixing therewith 10 grams of phosphorus sesquisulfide and the mixture again placed in the autoclave and heated for 5 hours with stirring at 220 to 230 F. In'those experiments in which air was excluded the autoclave was flushed with nitrogen and sealed and the reaction conducted at low superatmospheric pressure in a nitrogen or hydrogen sulfide atmosphere. In other experiments which were carried out in the presence of air an open autoclave was used. At the end of the heating period the base was pumped from the autoclave and cooled. Each sample of finished material was tested by the copper strip corrosion test and found to be non-corrosive.

Samples prepared, as just described, were blended with mineral lubricating oil in various amounts and tested on the 'Iimken testing machine to determine load carrying ability. The oil used in preparing the-blend was a mixture of the oil described in Table I and another Gulf Coast lubricating oil having the following characteristics:

Table II Flash point, F 510/520 Fire point, F 590/600 Vis. S. U. 210 F 150/165 Pour point, F 25 max. Color, N. P. A Bmax. Carbon residue, per cent lmax.

These oils were blended with the base so that the resulting blend had approximately the following characteristics:

Table III Vis. S. U. 130 F. in seconds- 1,100-1,215 Vis. S. U. 210 F. in seconds 160-- 170 Pour point, F., maximum 15 F.

The results obtained on a number of these blends are given in the following Table IV:

mosphere of air on the viscosity of the'product which was both sulfurized and phosphorized in the atmosphere of air. Comparing samples i to 3 with samples It and I5, it is evident that the exclusion .of air during the sulfurlzation step had a very beneficial eflect in keeping down the viscosity of the additive and materially improved the load carrying ability of the additive. 10 per cent of this additive when added to the mineral oil carried a much greater beam load on the Timken machine and almost withstood as high a pressure as did 18% of sample 1.

When samples 14 and 15 are compared with samples 4 to 9 it will be apparent that although phosphorization in air does increase the viscosity of the final material somewhat the increase is small compared to the increase resulting from sulfurization in the air atmosphere rather than an oxygen free atmosphere. Moreover, phosphorization in air rather than in an oxygen-free atmosphere does not appear to materially affect the load carrying ability of the resulting product.

Table IV Timken tests Per cent Sulfuriza- Suliurization Suliurize- Phosphoriza- Phosphog gzggg Sample vol. of base tion time ressure, tiou atmostion pressure, rization atsaybolt in blend in hrs. 1 5. sq. in. phere lbs/sq. in. mosphere versal at 210 F Beam Pressures, load, lbs. lbs/sq. in.

18 7. 5 Atmospheric Air Atmospheric 650 50 35, 750

14 7. 5 Atmospheric do. Atmospheric 678 51 30, 250

10 7. 5 Atmospheric do Atmospheric 678 43 27, 750

14 3. 5 Atmospheric 335 86 36, 500

10 3. 5 Atmospheric 335 86 35, 250

14 7. 5 Atmospheric 376 86 36, 500

' l0 7. 5 Atmospheric 376 77 34, 250

Lard 87.0 Mineral oi 5.0 Sulfur monochloride .5 Sulfur 7.4 Phosphorus sesquisulflde .4

In all cases with the two exceptions noted in the table the temperature for sulfurization was maintained at approximately 330 F. In all cases except in the case of the blank runs 16 and 17, which were not phosphorized, the temperature of phosphorization was 220-230 F. and phosphorization was carried out for a period of 5 hours.

By referring to the table it will be seen from samples I6 and I! that by sulfurizing the lard oil in an oxygen free atmosphere a sulfurized fatty oil base of relatively low viscosity is obtained. Samples I to 3 show the effect of an at- It was found, however, that if both the phosphorization and sulfuriaation was conducted in an atmosphere of hydrogen sulfide not only was the viscosity of the final product extremely low but the load carrying ability was extremely high. 10 per cent of this material (see sample 9) carried a considerably greater load than 18 per cent of the base made in an air atmosphere (see sample 1). Thus, I have found that if the sulfurization step is carried out in an inert atmosphere, a considerable improvement in viscosity and load carrying ability is obtained regardless of What atmosphere is used during the phosphorization step. But both these properties are greatly enhanced by carrying out the two steps in a hydrogen sulfide atmosphere.

The amount of pressure maintained in the autoclave during the cooking does not materially aflect either the viscosity or load carrying ability of the finished product.

Although the invention has been described with respect to treatment of lard oil, it should be understood that the invention is applicable to treatment of fatty bodies in general including various vegetable, animal and marine oils and waxes such as cotton seed, castor, rape seed and sperm oil. It should also be understood that the invention is applicable to sulfurization with either 7 sulfur or sulfur chlorides or any combination thereof. The proportions of sulfur in the final base should be within the limits of 1 to 20 per cent by weight, but preferably between 5 and 7 per cent.

Although the invention has been described using phosphorus sesquisulfide as the preferred phosphorizing agent it will be understood that other phosphorizing agents such as halides, oxyhalides, oxides and in general those phosphorus compounds disclosed in Patent 2,211,306 may be used. The phosphorus content of the finished additive should not exceed 2 per cent and is pref erably maintained between .2 and .6 per cent.

The temperature of sulfurization may vary somewhat, but in general it has been found that it should not be substantially below 320 F. and should be below 400 F. The temperature of phosphorization must be maintained within the approximate range of 220 to 230 F. to obtain a uniform product of desired characteristics.

In accordance with my invention I have been able to prepare an additive which may be added to mineral lubricating oils in relatively small amounts to impart desirable extreme pressure characteristics to the oil without materially increasing the viscosity thereof, thereby permitting the use of high flash oils. The additive prepared in accordance with my invention may be used in amounts ranging from as low as .5 to depending on the particular use to which the lubricant is put. In addition to functioning as an extreme pressure lubricant my additive possesses marked corrosion inhibiting properties so that when added to motor oils for lubricating metal bear ngs the bearing corrosion is very noticeably reduced. Where the additive is intended to function primarily as a corrosion inhibitor for preventing corrosion of metal bearing surfaces, it is effective when used in amounts of .05 to 5 per cent by volume based on the oil with which it is blended.

I claim:

1. The method of preparing a lubricant which comprises reacting sulfur and a fatty body under pressure at a temperature of 320-400 F. in a maintained atmosphere of hydrogen sulfide substantially free of oxygen and in such amounts as to incorporate from 5 to 7% by weight of sulfur in the fatty body, until the reaction product is non-corrosive as determined by the copper strip test and then phosphorizing the reaction product at a temperature of approximately 220- 230 F. until the final product is non-corrosive as determined by the copper strip test.

2. The method of preparing a lubricant which comprises reacting fatty oil with from 1 to 10% by weight of sulfur at a temperature between 320 and 400 F. under superatmospheric pressure in a maintained atmosphere of hydrogen sulfide substantially free of oxygen until the product is non-corrosive as determined by the copper strip test and phosphorizing the resulting product at approximately 220-230 F. for about 5 hours.

3. Method in accordance with claim 1 in which the product is phosphorized in an atmosphere substantially free of oxygen.

4. Method in accordance with claim 1 in which the reaction product is phosphorized. with phosphorus sesquisulfide in a hydrogen sulfide atmosphere.

5. Method in accordance with claim 1 in which the reaction product is phosphorized with phosphorus sesquisulfide.

6. The method in accordance with claim 1 in which the reaction product is phosphorized with phosphorus sesquisulfide in an atmosphere substantially free from oxygen.

7. The method in accordance with claim 1 in which the reaction product is phosphorized with phosphorus sesquisulfide in an atmosphere of hydrogen sulfide.

8. A non-corrosive, stable lubricant having a Saybolt Universal viscosity at 210 F. of less than 400 seconds and high load carrying ability, said lubricant being a sulfurized and phosphorized fatty oil having a sulfur content of 5 to 7% by weight, and a phosphorus content of .2 to .6% by weight.

9. Lubricant in accordance with claim 8 in which the viscosity is between 200 and 400 seconds.

10. The method in accordance with claim 1 in which the reaction product is phosphorized with phosphorus sesquisulfide in an amount to incorporate from .2 to .6% by weight of phosphorus in the product.

11. The method in accordance with claim 2 in which the reaction product is phosphorized with phosphorus sesquisulfide in an amount to incorporate from .2 to .6% by weight of phosphorus in the product.

WILLIAM A. WHI'IIIER.