US2590451A - Metalworking lubricant - Google Patents

Description

Patented Mar. 25, 1952 2,590,451 METALWORKING LUBRICANT George L. Perry, Berkeley, Calif., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application August 9, 1947, Serial No. 767,860

1 Claim.

This invention relates to novel lubricants and methods of making them. More particularly this invention pertains to metal working or metal fabrication lubricants for use in rolling, drawing, forging of metals and the like.

Problems encountered in lubricating metals under conditions referred to in the previous paragraph are particularly complex because of the various factors encountered such as high temperatures, excess pressure, emulsification, presence of foreign bodies or contaminants, work speeds and the like. To effectively lubricate under these adverse conditions the lubricant must act primarily as a coolant and lubricant.

In the field of rolling lubricants, palm oil was considered most efficient and suitable. However palm oil has serious drawbacks in thatit is diflicult to remove from metal surface thereby requiring the use of cleaners which greatly increases operating cost. Also it has a tendency to stain surfaces which on annealing mars the surface and exerts a detrimental effect when such metals are to be subsequently tinned, alloyed and the like. In addition metal surfaces which become too heavily coated with palm oil cause excessive slippage of the rolls thereby decreasing rolling efficiency. Palm oil is also very costly and scarce and a cheap and effective substitute for palm oil as a metal working lubricant is greatly. desired.

To meet the requirements demanded of a good metal fabricating lubricant such as a roll lubricant, it must have high absorption properties (low surface tension) to adhere on wet metal surfaces even in the presence of water. Also enough reduction of friction coefiicient must be realized to keep the mill from overheating.

Essential properties of such lubricants are: film strength, ability to reduce friction, ability to wet metals in presence of water, ability to produce a good lustre on metal surface worked, ease of removal and non-staining and de-emulsifying properties, i. e. separating from water and contaminants.

Film strength When lubricated metal surfaces are forced to slide past each other under high pressures there is a tendency for surface asperities to penetrate the lubricant film and adhere; this in turn permits the transfer of metal from one surface to another. This phenomenon known in metal working operation as pickup of the worked metal by the die or roll may become very pronounced at elevated temperatures. Although high temperatures may be a result of high friction and may lead to pickup, it is generally agreed that the ability of a lubricant to prevent adhesion of metal surfaces is a property distinct from and not necessarily related to ability of the lubricant to reduce friction between sliding surfaces which do not adhere, For this reason the ability of a lubricant to form surface films which prevent actual -metal to metal contact and. adhesion is very essential.

Reduction of friction Roll lubricants must possess the ability to reduce friction between the rolls and the work sheet in order to reduce power consumption, prevent overheating and minimize the force which must be applied to the rolls. The property of a lubricant to reduce friction is referred as oiliness and depends upon the sheer strength of the film formed on a metal surface and to the rheological behavior of thin films of oil when subjected to high pressures.

Wetabz'lity and adhesion Since roll lubricants are usually used in conjunction with water as a coolant, they must possess the property of displacing water from metal surfaces and resist the washing action of large quantities of water applied to the rolls and work sheet. Often washing water is applied in the form of a high pressure spray so that the ability of the lubricant to adhere to metal surfaces is of paramount importance.

Lustre The appearance of the surface of rolled stock referred to in practice as lustre" is markedly influenced by the character of the roll lubricant. To accomplish this, lubricants used for this purpose should be non-staining and prevent microscopic tears on the worked metal surface.

Ease of removal and non-staining A serious drawback of palm oil is the difnculty of removing it from rolled metal sheets. Generally electrolytic cleaners are required to remove the palm oil for if it is left on the metal surface and the metal is thereafter annealed the metal surface becomes stained. Roll lubricants should therefore possess the property of being easily removed when desired and also not stain the surface with which it is in contact, regardless of the temperature.

Corrosion resistant Efficient roll lubricants in additon to being able to withstand high temperature and pressure must be non-corrosive during the rolling process and preferably act as a corrosion inhibitor after the rolling process, particularly in cases where the rolled metal is stored for long intervals before being further worked.

It is an object of this invention to provide an improved roll lubricant substantially superior to palm oil. It is another object of this invention to provide a lubricant for metal working which is stable and non-corrosive. Still another object 9f this invention is to provide a tacky metal working lubricant having the property of resisting being displaced by water sprayed under pressure. Furthermore it is an object of this invention to provide a metal working lubricant which is non-staining and which can be easily removed from lubricated surfaces.

It has now been discovered that a metal work ing lubricant such as a roll lubricant can be prepared which possesses all of the above-desired properties and which in many respects is far superior to palm oil or roll lubricants containing as the main constituent palm oil and its derivatives, by forming a stable blend of a waxy hydrocarbon essentially non-aromatic and a light liquid petroleum fraction, the viscosity of which does not exceed around about that of gas oil. Stated somewhat differently it has now been discovered that excellent roll lubricants can be obtained by blending a non-aromatic waxy hydrocarbon with a liquid hydrocarbon having a boiling range of between about 300 to 7&0" F. and preferably below 600 F. The two constituents are blended in such proportions that the non-aromatic waxy hydrocarbon comprises a major part of the composition and preferably between 60 and 80% by weight, while the light liquid hydrocarbon comprises preferably about 20% and not above 40% of the total blend, the more preferred being between 20% and 30%. The waxy hydrocarbon base when diluted with a minor amount of a light hydrocarbon such as gas oil should have a buttery consistency at low temperatures but under conditions of use should possess the ability of spreading through water and on to the sheet beinglubricated without congealing or marring the surface. To this blend if desired substituent additives having the property of imparting extreme pressure properties, stabilizing the blend against oxidation, corrosion, deterioration and the like, may be added.

The main component of roll lubricants of this invention, namely, a waxy hydrocarbon or a hydrocarbon of wax consistency may be derived from petroleum fractions such as petroleum distillates or residues, or the waxy hydrocarbons may be produced synthetically by polymerization of olefinic materials by the Fisher-Tropsch process or by dehydration of long chain aliphatic alcohols having a minimum flash point of around about 500 F. and which do not vaporize at elevated temperatures such as encountered in rolling of metals under high pressures and temperatures.

Waxy hydrocarbons may be recovered from suitable petroleum fractions such as Pennsylvania crudes, East Texas crudes, Mid-Continent crudes and the like by de-asphaltizing the hydrocarbon and thereafter removing the wax from the asphalt free hydrocarbon fraction by any known suitable means. The asphalt may be separated from the oil either by distillation or solvent extraction although solvent extraction is preferred. In this process a solvent is selected in which the oil is relatively soluble but in which the asphaltic materials are relatively insoluble. Among such solvents are the light liquid hydrocarbons such as ethane, propane, butane, as well as naphtha and gasoline. Oils treated with such solvents extract the oil and wax leaving behind the asphaltic materials as residue. The wax-oil mixture may be removed from the asphalt-free solution by chilling the solution, and then separating the precipitated wax settling, filtering or centrifuging. Waxy materials thus produced are known in the art as slop waxes, petrolatumsto qk, 1

slack waxes, scale waxes, parafiin waxes, plate malcrystalline and needle waxes, micro-crystalline waxes and the like. These waxes are differentiated from each other by the degree of de-oil ing to which they are subjected and all of them may be used as one of the component parts of compositions of this invention.

De-waxing or separation of the above waxy constituents from the oil may be accomplished by selective solvent treatment using as the diluents liquefied normally gaseous hydrocarbons such as propane, butane, and other organic liquids such as alcohols, ethers, esters, ketones, aldehydes, acids and/or their mixtures. These may include methyl, ethyl, propyl, butyl, amyl alcohols; methyl or ethyl or methyl ethyl ether; acetones, diethyl, dimethyl, methyl ethyl, methyl isobutyl ketones and the like. Chlorinated hydrocarbons such as carbon tetrachloride or trichloroethylene and mixtures of chlorinated and non-chlorinated hydrocarbons as mentioned above may be used.

The first step in obtaining waxy constituents from petrodeum crudes, for example, such as Mid-Continent crude is to treat said crude with aboutsix volumes of liquid propane so as to remove the asphalt. The propane from the propane-oil, solution is vaporized so that the ratio of propane, to oil is reduced approximately 2 to l. Thesolution is then chilled to about F. and lower causing separation of the wax from the oil. The waxv can be removed by filtration and the propane separated from the de-asphalted and dewaxed oiland waxy material by distillation. A most. desirable wax fraction may also be obtained fromPennsylvania waxy steam cylinder stock by treating a waxy portion of said stock with methyl ethyl ketone so as to obtain two fractions, one being dewaxed oil and the other fraction being what is known in the art as whole wax. This whole wax is also treated with methyl ethyl ketone fromwhich again two separate fractions are obtained, one fraction being partially deoiled micro-crystalline residue wax which contains about 5 to 6% oil and has a melting point ofabout 130 F. and the other fraction being the so-oalled slop wax or foots oil having a melting point of about 65 F. The micro-crystalline waxes obtained from Pennsylvania waxy steam cylinder stock as disclosed in the previous sentences are mostly suited for rolling lubricants when blended with minor amounts, sufficient to inhibit congealing of the wax on the rolls and nips, of a light hydrocarbon boiling below the lubricating range such as gas oil and lighter liquid petroleum fractions.

Waxy materials can also be recovered from distillate or residuum lube oil fractions and these wax fractions can be split further into special wax cuts having desired characteristics by use of selective solvents. This is based on a difference in solubility of different waxy fractions in a given solvent. Thus when using a methyl ethyl ketone type solvent the aromatic constituents can be removed by successive cooling the mixture down to between about 40 to C. so as to remove the aromatics which become substantially soluble in the solvent, as the temperature is lowered while the straight chain waxes and isoparafiins become substantially insoluble in the solvent. The straight chain waxes can be separated from the isoparaffins by extraction and fractional crystallization. Depending upon the distillate cut used waxes of from 12 to abov e 36 carbon atoms and higher can be obtained.

within the gas oil range.

Broad range Viscosity at 210 F 62-134 Flash, "F 490-560 Fire, F. 560-640 Melting point, F -143 (25-70 preferred) M01. wt. 600 or higher Amount of oil, percent Not more than 40% Amount of aromatic, percent 0-2% Wax content, percent 60-100% (65-80 pre ferred) Specifically preferred waxes such as slop waxes have the following properties:

Ref. index, C 1.4796-1.4887

Percent solid wax 43-80% Percent liquids 20-57% Melting point 25-70 C. (25-40 0. preferred) Instead of obtaining natural waxes from petroleum in the manner indicated above, waxes can be produced synthetically by polymerization of olefins under pressure or dehydrating long chain fatty alcohols such as octadecyl alcohol and the like. Thus waxes can be prepared by catalytically dehydrating octadecyl alcohol at between about 375 to 450 F. to yield a mixture or mixtures of monomers and dimers of C18 and C36 olefins. If desired'these'fractions may be separated from each other by atmospheric steam distillation at 550 to 590 F. and moisture removed from the waxy fractions by any desired suitable means.

The diluent for the waxy base of this invention may be a liquid hydrocarbon having a boiling point below the lubricating oil range and preferably a hydrocarbon having a boiling point The amount of diluent used should not amount to less than 20% and should not exceed 40% of the blend and preferably should be kept in the range of 24 to 36%. If less than 20% of a diluent is used congealing takes and above 40% the blend becomes too fluid and is easily Washed away from the rollers, resulting in poor lubrication and appearance of the worked metal due to tearing action exerted on the worked metal by the rollers.

Although light petroleum hydrocarbon fractions of the gas oil boiling range are preferred as the diluent for the waxy hydrocarbon base other diluents such as mineral seal-oil, variouspetroleum naphtha cuts, mineral spirits, kerosene, kerosene S02 extract, petroleum ether, parafilnic hydrocarbons, e. g. normal hexane, dimethyl pentane, octane, iso-octane, undecane, dodecane, and the like may be used.

A preferred light hydrocarbon liquid has the following properties:

Flash, F 260 Viscosity at 100 F. U. S 46.5 Boiling range, F 490-700 A blend of a waxy hydrocarbon and light petroleum hydrocarbon of this invention suitable as a rolling lubricant may have the following properties for a blend of 20% gas oil and 80% slop wax.

Flash, F 320 Fire, F. 350 Viscosity at 210 F. 57.6 V. I. Q 142 Melting point, F. 92

These blends of waxy hydrocarbon and light petroleum hydrocarbon having a boiling point below that of lubricating oil may be, if desired, fortified with improving agents such as minor amounts of:

A. High molecular weight fatty acids derived from animal, vegetable, marine oils, e. g.

1. Animal oil tallow lard bone neats-foot wool fat horse foot oils, etc. 2. Vegetable oils castor cashew peanut cocoanut jojoba seed olive olive kernel palm oil palm kernel oils corn cottonseed kapok rapeseed ravison sesame sunflower teaseed oil, etc. 3. Marine oils codfish codliver dogfish dolphin body dolphin fish herring J apfish menhaden porpoise body and jaw oils salmon oil sardine and sardine liver oils seal oil shark and shark liver oils sperm whale body and head oils whale oil, etc.

B. Naturally occurring fatty acids of high molecular weights 1. Saturated capric' undecylic lauric myristic palmitic stearlc arachidic lignoceric cerotic montanic acids, etc. 2. Unsaturated oleic linolelc erucic linolenic brassidic elaidic V Substituted fatty acids ricinoleic ,ricinelaidic hydroxystearic acids, etc.

was held between about 150 and 175 F. The total rolling pressure. was measured with a constrained capsule-type pressure gauge placed between the screw down and the bearing chock. The efliciency of each roll lubricant tested was determined from the ratio of total rolling pressure in pounds 100. extension in inches on the metal being worked. This ratio is a good comparative criterion of the coefiieient of friction developed by the lubricant on the worked surface.

Initial Total Exten- Ratio Pressure Roll Composition Pressure Pressure sion W Temper- Remarks (pounds) (pounds) (inches) 1 X 91151011 ature 1. Mineral lubricating 50,000 78.0 10 3 3.00 260 155 Unsulted for rolling. oil. Easily-washed away.

2. Gas Oil 50,000 1.57 155 Same as 1.

3. Commercial Niger- 50,000 33.8X10- 5.60 121 155 Diflicult to remove. ian Palm Oil. stains metals and has tsoliiie c ongeal' mg en eneies.

4. 80% Short Residue 50,000 82.0Xl0 11.1 77 0 155 Tends to only slight- Petrolatum and ly congeal, but does gas oil. not stain metal and easily remove 5. 80% microcrystalline 50,000 82.0Xl0 3 8.2 80.3 155 No tendency to conslop wax and 20% gas geal, does notstaiu oil. metal and is easily removed.

Test II D. Sulfur containing materials, e, g.

dibenzyl disulfide sulfurized sperm oil sulfurized cottonseed oil sulfurized fatty acids as listed under part B The above fortifying agents maybe excluded from the rolling lubricant of this invention or added to the roll lubricants in very minor amount generally not exceeding 10% of the total composition. Smaller amounts of fortifying agents such as 1-2% are generally preferred.

To illustrate more clearly the present invention, the following examples are presented. It is to be understood, however, that various modifications can be restored without departing from the spirit of the invention as presented in the subjoined claims.

Test 1 Steel metal strips of standard size x 5") and gauge (.0102") were rolled on a rolling mill under an idling gage pressure of about 50,000 pounds. The mill was run at a controlled speed, cooling water being applied also at a controlled rate and the lubricant tested applied at a temperature of about 200 to 240 F. The temperature of the rolls at the exit side of the roll nips Another method of determining the. efiiciency of roll lubricant is by the lustre test: which is. a measure of the degree of freedom from surface tearing during rolling of metals. The device used consistsessentially of a light source from which light is directed onto an area of a rolled sheet at 45, and the amount of light reflected at 45 is measured with a G. E. photo-electric light meter. The. numbers recorded are, footcandles reflected light where the theoretical perfect reflector would give a reading of approximately foot-candles.

A black plate before being rolled has a reading of approximately 58 foot-candles.

LUSTRE Ol? METAL PLATE AFTER BEING ROLLED WITH VARIOUS LUBRICANTS One of the most important properties of a good rolling oil in addition to its non-congealing properties and the ability of imparting lustre, a i. e. its ability to prevent the tearing of the metal during rolling, is its ability of being easily removed and not leave on the metal surface lacquer-like stains on annealing.

To determine the lacquer staining properties of roll lubricatings the following procedure was followed. A drop of oil was placed on a panel of fully deoxidized black plate and inserted in a small tube furnace at 200 F. with an atmosphere of dry, oxygen-free nitrogen. The temperature was then raised to 1225 F. and held for 9 20 minutes. The furnace was then cooled to 200 F. and the annealed panel removed and examined for stains caused by the oil.

Composition Remarks 3. 80% mierocystallinc slop material formed on panel.

wax+20% gas oil.

Rolling lubricants of this invention are well adapted as rust inhibitors after the rolled sheet has been worked.

The roll lubricant of this invention may be applied to the rolls of a sheet metal rolling mill by any suitable means such as spraying, dripping or the like. It may be applied on the sheet metal prior to. during or after rolling. Preferably the lubricant is warmed to about a temperature of 150 to 175 F. before applying it to the rolls so as to aid in spreading the lubricant more evenly on the rolls and work piece.

In addition to being an excellent roll lubricant, compositions of this invention may be used as drawing lubricants, forging and die lubricants and in various other processes where drawing and working of metals requires lubrication.

It is to be understood that while the features of the invention have been described and illustrated in connection with certain specific examples, the invention, however, is not to be limited thereto or otherwise restricted'except by 10 the prior art and the scope of the appended claim.

I claim as my invention:

A metal fabricating lubricant consisting essentially of a blend of a mierocrystalline slop wax and from 20% and 40% by weight of gas oil and a minor amount of from 1% to about 5% by weight of polyalkylene glycol diester said diester compound being compatible with said blend.

GEORGE L. PERRY.

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

UNITED STATES PATENTS Number Name Date 1,655,373 Keller Jan. 3. 1928 1,716,310 Gray a- June 4. 1929 1,920,161 Rosen July 25, 1933 2,126,128 Montgomery Aug. 9, 1938 2,151,353 Montgomery Mar. 21, 1939 2,153,811 Montgomery Apr. 11, 1939 2,203,507 Roehner June 4, 1940 2,210,140 Colbeth Aug. 1, 1940 2,256,603 Wright Sept. 23, 19 1 2,258,930 Haefner Oct. 14, 1941 2,294,535 Burnwell Sept, 1, 1942 2,298,844 Schilling Oct. 13, 1942 OTHER REFERENCES Chemicals by Glyco, Glyco Products Inc, 1944, pp. 15 and 25.