US2196101A - Lubricating oil - Google Patents

Description

Patented Apr. 2, 1940 11 Claims.

i1'Ihis invention relates to improved lubricating o s.

In one aspect it relates to improved oils used in rolling mill operations, particularly in rolling al- 5 loy steels and aluminum.

In another aspect it relates to improved lubricating oils for lubrication of steam cylinders, air compressors, vacuum pumps, and for similar service.

10 It is one of the objects of this invention to provide roll oils of increased film strength which in I turn raises the efliciency of rollingoperation by allowing the application of higher pressures to the rolls and obtaining a higher reduction of met- 15 al per pass. A further object is to provide roll oils capable of preferential wetting of metals in the presence of water. It is also the object of this invention to provide roll oils which are noncorrosive to metals under the processing condi tions existing at the rolling mills during the rolling and annealing steps, and which lead to the production of stain-free, bright metal surfaces upon annealing and conventional burnishing.

Particularly, the present invention is intended to solve difficulties associated with the rolling and annealing of alloy steels such as stainless steel, and of aluminum.

While heretofore some of the above objectives were partly attained by mineral and fatty oils, or by mixtures thereof, the present invention enables the trade to attain them simultaneously.

It is another of the objects of this invention to provide lubricants which possess greatly decreased tendency to carbonize in service in steam and gas engines and air compressors, which in turn leads to increased efiiciency in operation and prolonged cycles between the shut downs for cleaning purposes. It is also the object of this invention to provide lubricants with highly pronounced preferential wetting power toward metals, or in other words, with higher resistivity to the washing effect of steam, air, gas and condensate. The novel oils also lend themselves readily to atomization.

Roll oils are used in metal rolling mills in'the process of conversion of the billets into sheets and strips and also for further reduction of the sheets and strips to specified gauge. The roll oil is applied to the metal just before it passes between the rolls where the reduction to gauge takes place. Several passes throughroll stands are usually required, and each pass involves the appli'-'- cation of roll oil. The latter may be used straight or concurrently with a water spray. The function 56 of'the rolloil is lubrication, prevention of oxidation of the metal and removal of heat. In order to perform these functions satisfactorily, the roll oil must be non-corrosive, possessadequate wetting power toward dry or water wet metals, and 60 form a film of suflicient strength to withstand the v 2,l96,ll UNITED STATES PATENT OFFICE LUBRIGATING on.

Emmett C. Carmichael, Jackson Heights, Richard J. De Gray. Forest Hills, and John H. Prall, Brooklyn, N. Y., assignors to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New' York No Drawing. Application September 23, 1938,

Serial No. 231,328

pressure of the rolls. Furthermore, subsequent to the rolling, the manufactured metal goods may be subjected to an annealing process to relieve the stresses in the metal. The annealing comprises heating, in either reducing or oxidizing atmosphere, to a high temperature specific to the particular metal under treatment, followed by comparatively slow cooling. As the temperatures prevailing in the anealing ovens are in the range of 550 F. to 2000 F., the roll oil film partly volatilizes and partly decomposes. It is essential that no stains or oxide films not removable by conventional burnishing operations remain on the metal as a result of incomplete removal, or carbonization of the roll oil, or of any chemical reaction betwen the roll oil and the metal. Otherwise, the removal of unsightly oxide films and stains would involve prohibitive mechanical cleaning or rejection.

A wide variety of oils, such as mineral hydrocarbon oils, made from petroleum by known methods of refining; fatty oils of animal and vegetable origin, as well as blends of mineral and fatty oils, with and without emulsifiers, have been used for metal rolling.

We have discovered that a roll oil consisting of a high percentage of mineral oil and a small percentage of nitrated iatty oil possesses outstanding performance characteristics not observed in similar products known to the art heretofore.

As an example of improved roll oil covered by this invention, we may cite the following composition:

Per cent Nitrated tallow 2 Paraifin oil 98 The physical properties of the blend are as follows:

Gravity, A.P. I 311 Flash, C. O. 0., "F 315 S. U. viscosity-Q) 100 F 54 v Color Light e /z Conradson carbon residue, 0.09 Pour, TL

Mineral oils, suchas made by refining of petroleum have been known as satisfactory lubricants for a wide variety of applications. However, there are numerous cases in which the oil film has .to withstand the action of air, gas, steam and in various parts of the engines, particularly on the exhaust valves and in piston grooves because of the decomposition of hydrocarbons under the described severe operating conditions.

For better distribution of the lubricant inside the cylinder and for lower consumption, it has been found advantageous, in certain cases, to introdu'ce the lubricant in a finely atomized state. This method has been widely used in steam cylinder lubrication.

In ,order to meet the above requirements in cases in which straight hydrocarbon oils have faded, so-called compounded lubricants have been developed and used. The latter consist of mineral oils of proper characteristics and comparatively small admixtures of fatty oils and fatty acids of animal and vegetable origin. Tallow, neats-foot oil, and elaine oil are common examples of fatty materials in compounded lubricants of the above classes. Compounded oils have shown better performance than straight mineral oils with respect to metal wetting, ease of atomization and softer carbon deposits.

We have discovered that compounded lubricants consisting of hydrocarbon oils of appropriate viscosity and other characteristics, and of smaller amounts of nitrated fatty oil possess outstanding properties for' meeting the conditions existing in steam engine, gas engine, vacuum pump, and air' compressor lubrication, and in similar service.

The following composition formulae are representative of the novel cylinder lubricants disclosed in the present speciflcationt The nitrated tallow is a product of reaction between common tallow. and concentrated nitric acid. When the two reactants are heated to 220- 230 F'., an exothermal reaction occurs, the temperature rising to 250-280 F. without additional heat. The excess mineral acid is washed out with water, upon cooling, and the product is dried. The following table illustrates the properties of the original common tallow and the nitrated tallow:

Common Nitrated tallow tallow The paraflin oil (used in roll oils) is a light mineral oil of approx. 50 seconds viscosity at 100 F. (Saybolt Universal).

The blended roll oil is prepared by simple stirring of the two ingredients at a temperature above the melting point of the nitrated fat.

The mineral oils used in the above cylinder oil formulae are hydrocarbon oils made from petroleum by known methods of refining. Their viscosities are 300 vis. Say. Univ. at 100 F. and

230 sec. Say. Univ. at 210 F. for the compressor oil and the steam cylinder oil, respectively.

The nitrated tallow and mineral oil are combined by mixing at a temperature above the melting point of the nitrated fat.

Subject to various applications in compressor, vacuum pump, gas engine. and steam cylinder lubrication, the mineral oils may vary in broad limits. E. g., the preferred ranges for steam cylinder and compressor oils are as follows:

I Minimum Maximum 300" 8. U. vis. @310.

60" s. U. vis. @210.

600" s. U. m. 100.

For steam cylinder oila 150" S. U. ms. @100.

Compressor oils a convenient measure of the degree of nitration.

While in the above example, the nitrated tallow shows an iodine number 23.8 points lower than the original tallow, (30 vs. 53.8), more or fewer nitro groups can be introduced, the upper limiting point being the stability of the solution of the nitrated product in mineral oil. E. g., common tallow can be nitrated to final iodine numbers ranging from 50 to 15. For other fatty oils these numerical values are different.

The percentage of the nitrated fatty oil in the finished lubricant may be changed within the following limits: 0.25% to 25%. I

The composition of the novel lubricants covered by this invention is not limited to a binary blend of mineral oil and nitrated fat. It has been found advantageous, in certain cases, to add nitrated fat, within the above limits, to compounded oils already containing fats or fatty acids. As an example 01' such product, we may cite the following formula of a steam cylinder oil:

' Percent Mineral oil 150'sec. Say. Univ. 0 210' IL--- 92 Acidless tallow '1 Nitrated tallow 1 The relative load carrying capacities of roll oils can be conveniently indicated by the Almen pin test described by Moughey and Almen (Proc. A. P. I., 1931, page 7'7). This test is conducted in a specially designed machine the essential parts of which are a rotating pin and a bearing lubricated with the oil in question. Increasing loads are applied to the lubricated surface imtil the oil film fails. The following tabulation shows the effect of addition of nitrated fat to a 100" Product 100" Saybt. Univ. Q 100 1. paladin oil Sam: nitrated. sperm oil LbeJsq in.

failure woo woo com 0600 7000 moo Bame-- ,nitrated sperm oil Commercial roll oil (containing 7% dcgrai) The ability of the novel roll oils to leave a bright metal surface after exposure to high temperature in annealing ovens can be demonstrated by the following comparative tests:

Highly polished plates of 18-8 chromium nickel stainless steel were slushed with various roll oilsand annealed at 1700 F. for 3 minutes in an oxidizing atmosphere. The inspection of the plates disclosed the following results:

Product Appearance of metal surface 1 Parafilmo n all 50 sec. 8. U. vis. Dull oxide coating, no rust. 2 Same 98%+2% nitrated tallow Brightt clean oxide film; no

rue 3 Same 08%+2% nitrated sperm oil. Do. 4 Same 90%+l0% nigor palm oil. Rust spots. 5 Niger palm o Do. 6 Commercial roll:

08% 50 sec. @100 F. paraflln Rust slams.

oil 7% degree.

The best way of proving the value of the lubricating oils covered by this invention is field testing in full size engines. This has been done on .steam and gas engines, compressors and vacuum pumps and reports are on hand confirming the fine performance, particularly the low carbonization tendency and high preferential wetting power of the oils containing the nitrated fats,

We claim:

1. Improved mineral lubricant oil compositions comprising a major proportion of a viscous mineral lubricating oil fraction and a minor proportion of a nitrated fatty oil.

2. A mineral lubricant oil composition comprising a and in addition thereto a small proportion, from about 0.25% to about 25.0% of a nitrated fatty oil.-

4 3. A mineral lubricating oil composition com- I operations comprising a light cylinders, compressors,

viscous mineral lubricating oil fraction composition comfraction and from 0.25%

tallow.

7. 'A lubricant composition for use in rolling operations comprising a light viscous mineral oil fraction and about 2% oinitrated tallow.

8. A lubricant composition for use in rollin operations comprising a light viscous mineral oil fraction of about 2% ing an iodine number of about 30.

9. A lubricant composition for use in lubrication of steam cylinders, compressors, and the like, comprising a heavy viscous mineral oil fraction and-from 0.25% to 25.0% of nitrated tallow. 10. A lubricant composition for use in steam a heavy viscous mineral oil fraction and from about 0.75% to about 4.0% of nitratedtallow.

11. A lubricant composition for use in steam cylinders, compressors, and the like comprising a heavy viscous mineral oil traction and from about 0.75% to about 4.0% or nitrated tallow having an iodine number of about 30.

nmmrr s. caamdnam... RICHARD J. DE GRAY. JOHN H. PRAIL.

addioil fraction and in addi- (tion thereto a small proportion of nitrated talof nitrated tallow havand the like comprising