US2069790A - Lubricant - Google Patents

Description

j Paten ted Feb. 9, 1937 UNITED STATES PATENT OFFICE 1 LUBRICANT No Drawing. Application October 10, 1934, Serial No. 747,766

12 Claims.

This invention relates to lubricants of the type designed for use in the extreme pressure field, and has particular reference to a new composition which gives exceptional film strength, ad-

hesion and resistance to abrasion. In particular, it contemplates the use of a chlororetene as an addition agent to lubricating oil, to produce a lubricant satisfactory for extreme pressure work, and for machine cutting, threading, etc.

For most common purposes, the ordinary petroleum base lubricating oils are satisfactory. With very rapidly moving machinery, and especially with gears of the hypoid and herringbone type, extremely high pressure is developed;

1-5 and the ordinary oil lubricants lack suficient film strength to maintain a continuous film on this type of gearing. For example, a straight Pennsylvania lubricating oil of 155 seconds Saybolt at 210 F. will only resist pressures up to 8,000 to 20 9,000 pounds per square inch, while these gears develop pressures requiring lubricants able to resist up to 20,000 pounds and higher. With the acceptance of these gears by automotive engineers for common use on automobile rear ends,

25 a demand has arisen for cheap, efiective, ex-

treme pressure lubricants of high film strength. Various products have :been suggested and used, with partial satisfaction only.

Halogenation'of the lubricating oil itself has 30 been suggested. This is unsafe, as the aliphatic halides formed tend to hydrolyze under adverse conditions, making the lubricant acid and cor rosive to the gear surfaces. I

Ortho-dichlor benzene has been suggested, but

5 its low boiling point (352 F.) and its low viscosity at elevated temperatures (34-36" Saybolt at 210 F.) are objectionable, its tendency to evaporate being the most important factor against its use.

40 'Ihechlor-naphthalenes have been used, but

optimum results cannot be obtainedowing to the limited solubility in most lubricating oils.

In our co-pending application Serial Number 716,004, of which this application is acontinua- 45 tion in part, we disclosed that monochlororetene (in combination with lubricating oils) makes very good extreme pressure lubricants, combining high film strength, excellent adhesion, good viscosity at elevated temperatures, good misci- 50 bility with lubricating oil, low vapor tension, and

resistance to hydrolysis, with reasonable cost and availability.

' Monochloroetene is at ordinary temperatures a pale amber, viscous liquid which possesses per- 55 feet miscibility with lubricating oil, It boils at about 215 C. at 4 mm. pressure and has a viscosity of 54-58seconds Saybolt at 210 F. It is extremely stable, as it may be boiled for hours with caustic solution without any indication of hydrolysis. Its adhesion to metal is outstand- 5 ingly good.

On mixing small percentages of monochlororetene with lubricating oil, a noticeable increase in film strength is obtained. 'This increases in al- A most a straight line relationship until a blend 10 of approximately l5% monochlororetene and 85% lubricating oil is obtained (about 2% total chlorine) the curve then flattens out almost to a horizontal line.

We have now found that when the polychlorinated retenes are used, together with lubricating oils, in the preparation of extreme pressure lubricants, even better results are obtained, as to film strength and other desirable properties, than with the monochlorbretene lubricants. As the degree of substitution increases, the maximum film strength obtainable increases, the film strength obtainable with hexachlororetene being more than double that obtainable with the monochloro compound.

While monochlororetene has been prepared in the past, and may be rather easily prepared and purified, the polychlororetenes are new compounds which are' somewhat more dimcult'to purify. The dichlor compound may be prepared by direct chlorination of melted retene, and purifled by washing or by vacuum distillation; but the tri and higher chloro compounds decompose on vacuum distillation and cannot be easily prepared from the molten retene, due to foaming of the reaction mix. The preferred method of making these compounds isto chlorinate in the presence of a solvent, preferably an equal volume of carbon tetrachloride. The crude product, containing asphaltic material, hydrochloric acid, chlori- 4o nated retene and solvent, is then purified, separating the solvent, acid and asphaltic material from the polychlor compound. One method is to steam distill off solvent and acid, and dissolve the residue in petroleum naphtha; the insoluble asphalts are then separated from the solution, and the solvent is removed from the polychlororetene by distillation. Further washing with water and/or dilute caustic soda solution, toremove any possible traces of acid, may be resorted to, but. is in general not essential to obtaining a pure product on the lower chlor compounds. This washing is very helpful, however, on the more highly chlorinated compounds.

Another method is to filter the reaction mixture through fullers earth. Asphaltic material is filtered oil, and free acid is absorbed; the solution of chlororetene may then be treated to remove the solvent, to give a fairly pure technical product.

The dichloro compound is a very viscous oil; and the products range through plastic solids to the hexa chloro compound, which is a hard resinous material, with a ball and ring melting point of 138-142 F. It powders readily, but the powder tends to sinter somewhat at high summer heats (ca. F.) All of the compounds are completely soluble in lubricating oil.

The following examples will indicate the superior results obtained with our new lubricating compositions:

Example 1 454 grams of monochlororetene were mixed with 2,500 grams of Pennsylvania #150 (viscosity 150 seconds Saybolt 210 F.) bright stock, to give a mixture containing 2% chlorine. The resultant lubricant was tested on a Timken Lubricant Tester (the standard device for testing lubricants of the extreme pressure type), giving an O. K. load of 33 pounds (approximating a pressure of 20,000 pounds per square inch) and a score load of 38 pounds (22,500 pounds per square inch). A reduction to 1 5% chlorine content in the mixture reduced the lubrication under load considerably; increase to 3% chlorine content resulted in no increase in load values.

A six hour run at 33 pounds load gave an abrasion of .0045 gram; after the 6 hour test, the original results were obtained on the O. K. and score loads, demonstrating the stability of the compound under load conditions over a period of time.

Example 2 171 grams of dichlororetene, prepared by chlorination in solvent, and subsequent purification by steam distillation, naphtha solution, filtration and solvent evaporation, were mixed with 2,500 grams of Pennsylvania #150 bright stock (the standard lubricating oil used on the Timken Tester) and thelubricant obtained, containing 1%% chlorine was tested as in Example 1. An 0. K. load of 25 pounds (15,000 pounds per square inch pressure) and a score load of 33 pounds (20,000 pounds per square inch pressure) was obtained. A blend of the 234 grams of dichlororetene with 2,500 grams of the same oil (clflorine content 2%) gave a 38 pound O. K. load (22,500 pounds per square inch pressure) and a score load of 43 pounds (25,000 pounds per square inch pressure).

Example 3 118 grams of hexachlororetene, purified as was the dichloro compound of Example 2, with the further step of washing with dilute caustic and water, was blended with 2,500 grams of the Pennsylvania #150 bright stock, to give a 2% chlorine content. An 0. K. load of over pounds (approximating 57,000 pounds per square inch pressure) was obtained, with no scoring. The machine was run 6 hours with a 33 pound load; an abrasion loss of .0035 gram was found. After the test, the compound was again subjected to the 100 pound load, and found 0. K.

Example 4 A blend similar to that of Example 3 was made up, using a hexachlororetene purified as in Example 3, but with the final caustic wash omitted. An 0. K. load of '77 pounds (45,000 pounds per square inch pressure) was obtaine wi h a score load of 86 pounds (50,000 pounds per square inch pressure). A 6 hour run at 33 pound load gave .0045 gram abrasion; a test after the abrasion run gave the same 0. K. and score loads as originally.

Other chlorinated retenes give results which vary from those obtained with the mono compound, to those which are obtained with the highest chlor compound we have testedhexachloro retene; and our results indicate that as the chlorination of the retene molecule is increased, the possible film strength obtainable is increased, without increasing the amount of chlorine in the finished lubricant. The amount of addition agent needed is, of course, reduced as the chlorination is increased. A 2% chlorine content in the lubricant requires, on a 2,500 gram basis, only 118 grams of the hexachloro compound, against 454 grams of the mono compound.

A further advantage in using the polychloro compounds lies in their superior non-volatility. While the monochloro compound is relatively nonvolatile, boiling at 642 F. under normal pressure, with decomposition, the polychloro compounds become less and less volatile, the hexa compound being to all intents entirely non-volatile. This reduces loss of vfilm strength during prolonged use.

Unlike some other series of chlorinated compounds, the chlororetenes retain their good oilsolubility even in the higher chloro compounds. This is, of course, a prime essential in compounds which are to be mixed with lubricating oil.

As indicated by the abrasion test, a properly purified polychlororetene lubricant is as resistant to hydrolysis as the monochlororetene lubricant.

While we have shown in our examples only the tests with Pennsylvania bright stock, the polychlororetenes may be employed with other lubricating oils, and with blended compositions and greases, compounded from Mid-Continent, California or foreign crudes.

Although particularly intended for extreme pressure work, our lubricating compositions may, of course, be used for other purposes, as for auto cylinder oil, cutting oil, etc. In these cases, thinner oils should be used than for extreme pressure work. The adhesion of our lubricants, and their resistance to high pressures, make them especially valuable in the preparation. of cutting oils; while small quantities of the polychlororetenes, added to ordinary cylinderv stock, improve the lubricating properties considerably.

' Polychlororetene, as defined in the claims, means an individual compound, or a mixture of the polychlororetenes.

We claim:

1. A lubricant comprising a hydrocarbon lubricant material and a chloro derivative of retene.

2. A lubricant comprising a hydrocarbon oil and a chlororetene.

3. A lubricant comprising a mixture of hydrocarbon oil and chlorinated retene, the chlorine content of the mixture being about 2%.

4. A lubricant comprising a hydrocarbon lubricant material and a polychlororetene.

5. 'A lubricant comprising a hydrocarbon oil and a polychlororetene.

6. A lubricant comprising a hydrocarbon oil and a polychlororetene, the chlorine content of the mixture being about 2%.

7. A lubricant comprising a hydrocarbon lubricant material and dichlororetene.

8. A lubricant comprising a hydrocarbon lubricant material and hexachlororetene.

9. A lubricant comprising a hydrocarbon lubri'cant material and dichlororetene, the chlorine content of the mixture being about 2%.

10. A lubricant comprising a hydrocarbon lubricant material and hexachlororetene, the chlo- 5 rine content of the mixture being about 2%.

11. A lubricant comprising a hydrocarbon lubricant material and monochlororetene.

12. A lubricant comprising a. hydrocarbon lubricant material and monochlororet'ene, the chlorine contentof the mixture being about 2%.