US2387170A - Low temperature lubricants - Google Patents

Description

Patented Oct. 16, 1 945 umreo STATES PATENT orrlce LOW LUBRICANTS John 1). Morgan, South a N. 1., asslgnor to Cities Service Oil Company, New York, N. Y., a corporationof Pennsylvania No Drawing. Application August 27, 1942,

Serial No. 456,366

11 Claims.

This invention relates to low temperature lubricants. More particularly the invention relates to lubricants made from synthetic compounds which have proper physical properties for low temperature lubrication.

I have discovered that Decalin (Ciel-11a), decahydronaphthalene, and Tetralin, tetrahydronaphthalene (Ciel-In), have good lubricating characteristics. Decalln has a boiling point of 379 F. and a freezing point below 55 F. Tetralin has a boiling point of 404 F. and a freezing point below -40 F. Both of these are col-' orless liquids and have better lubricating characteristics than a neutral mineral oil lubricant, that is a neutral oil having a viscosity of 100 at 100 F. However, alt-1% of one of the well known extreme pressure additives is added to Tetralin and Decalin, lubricants of high loadcarrying characteristics will be formed.

With these viscosity values it is apparent that the viscosity temperature curves are practically fiat and therefore there is little changein' the temperature range in which a lubricant ordinarily is operative. Due to the fact that the viscosities are so lowat. the low temperatures, Tetralln and Decalin are well adapted for low temperature lubrication, v

Decalin andTetralin are compatible with the alkali and alkaline earth metal with Tetralin or Decalin to produce satisfactory greases. It is preferred furthermore'to add an extreme pressure additive to the Tetralin or Decalin before they are blended with the soap in making the greases; for example, from 0.1% to 1% of the additive, thereby producing greases having extreme pressure load-carrying characteristics.

Tetralin and'Decalin have a tendency to oxidize but it has been found that if a small proportion of from .01% to 0.1% of one of they/e11 known antioxidants is dissolved in the Tetralin or Decalin they become very stable. For example from .01 to .1% of hydroquinone, py ogallol, or a-naphthol are very efiective -antioxidants for stabilizing Decalin and Tetralin.

The extreme pressure additives which may be i used with Tetralin and Decalin may be any of the well known additives that are commonly used for treatment of mineral oil lubricants. A small proportion of the extreme pressure additive or agent, for example, from 0.1% to 1%, is efi'ective to impart extreme pressure properties to the lubricant. Polane, a commercial extreme pressure agent which is known as chlormethyl stearate may be used. Tricresyl phosphite or a ,mixture of tricresyl phosphite and tricresyl phosphate are efi 'ective additives. The sulfurized tricresyl phosphine extreme pressure agents described in Engelke Patent No. 2,260,303, granted October 28, 1941, may be used, as also the suliurized tin salts of alkyl phenol. carboiwlic acids as described in Patents Nos. 2,197,834-5; 2,256,- l il; and 2,257,751.

When making the greases the extreme pressure additive and the antioxidant are dissolved in Decalin or Tetralin, and then the treated hydronaphthalenes are blended with the soaps of lithium, calcium, or aluminum. Preferably the aluminum soap is used in conjunction with the cal- I cium or lithium soaps. A preferred product comprises from 4% to 15% of lithium stearate,

soaps for the pro duction of greases which stay in stable emulsion.

The lithium, calcium andaluminum soaps are mutually soluble in Tetralin and Decalin. Preferably the metal soaps are stearates but the oleates and palmitates will blend with Decalin to.

form good greases. It has beenfound that from x 4 to 20% of these metal soaps maybe blended from 1% to 3% of aluminum stearate, from 0.1% to 1% of Polane," from 0.01% to'0.1% of pyrogallol, the remainder-of the product consisting essentially of Decalin or Tetralin. Other greases may be made containing from 4% to 20% of a metalsoap of a. fatty acid such as lithium stearate or one of the other soaps mentioned above,

the remainder of such greases consisting essentially of Decalinor Tetralin. These greases may contain asmall proportion of an antloxidant'or a small proportion of an extreme pressure agent, or both.

Decalin and Tetralin may be mixed together in I ium stearate.

most any desired proportion forum as a lubricant. or for use in making a. grease which may contain from 4% to 20% of a soap such as lith- Decalin and Tetralin are formed by the hydrogenation of naphthalene. The hydrogenation of naphthalene to form Decalincan be carried out to form isomeric compounds, the cisand trans- Decalins. Each of these isomers may be used as a lubricant. All of the polyhydronaphthalenes tested have been found to have lubricating properties, and the extreme pressure additives are soluble in all of the polyhydronaphthalenes to provide: extreme pressure lubricants. The po1yhydronaphthalene lubricants may contain from 0.1% to 1% of .an extreme pressure agent, or from 0.01% to 0.1% of an antioxidant, or both an extreme pressure agent andan antioxidant in about these proportions.

The preferred form of the invention havin been thus described, what is claimed as new is:

1. A low temperature lubricant consisting es-' asazrro 4. A low temperature lubricant consisting essentially or Tetralln having dissolved therein a small proportion of an extreme pressure agent suiiicient to impart extreme pressure properties to the lubricant.

5. A low temperature lubricant consisting essentially or a mixture of Deealin and Tetralin having dissolved therein a small proportion of an extreme pressure agent suficlent to impart extreme pressure properties to the lubricant.

6. A low temperature lubricant comprising from about 4% to 20% of a. metal soap of a fatty acid, the. remainder of the lubricant consisting essentially of Decalin.

7. A low temperature lubricant comprising from about 4% to 20% of a metal soap of a fatty acid, the remainder of the lubricant consisting essentially of Tetralin.

8. A low temperature lubricant comprising from about 4% to 20% of lithium stearate, the

remainder of the lubricant consisting essentially I of Decalin.

sentlallyof a polyhydronaphthalene having dlssolved therein a small proportion of an extreme pressure agent sufilcient to impart extreme pressure properties to the lubricant.

2. A low temperature lubricant consisting essentially of a polyhydronaphthalene having dissolved therein a-smali proportio'n'of an extreme pressure agent and a small proportion of an antioxidant, said agent and antioxidant being present in suillcient proportion to respectively impart extreme pressure properties to the lubricant and to protect the lubricant against oxidation.

3. A low temperature lubricant consisting essentially of Decalin having dissolved therein a small proportion of an extreme pressure agent suflicient to impart extreme'pressure properties to the lubricant.

mainder oi the lubricant consisting essentially of Decalin.

' JOHN D. MORGAN.