US3600310A - Lubricant for metal working - Google Patents

Abstract

THE PRESENT INVENTION PROVIDES A SUPERIOR METAL ROLLING LUBRICANT COMPOSITION USEFUL AS A PRE-COATING OIL AND AS A COATING IN ROLLING OPERATIONS COMPRISING A MINERAL OIL, A FATTY ACID OR THE POLYMERS OR GLYCERIDES THEREOF, AND A WAX, PREFERABLY A PARAFFIN WAX SUCH AS SLACK WAX. THE COMPOSITION MAY ALSO CONTAIN A SULFURIZED MINERAL OIL, OR FATS, OR OTHER SULFUR-CONTAINING COMPOUNDS, AS WELL AS ORGANIC PHOSPHATES OR PHOSPHITES TO PROVIDE INCREASED PROTECTION TO THE METAL SURFACE DURING COILING AND UNCOILING. THE LUBRICANT COMPOSITION PROVIDED IS PARTICULARLY USEFUL IN THE COLD ROLLING OF STEEL.

Description

3,0003% Patented Aug. 17, 1971 3,600,310 LUBRICANT FOR METAL WORKENG Alan R. Eyres and Jacques C. Dillon-Corneck, Mullica Hill, NJ, assignors to Mobil Oil Corporation, New York, NY.

No Drawing. Filed Mar. 20, 1969, Ser. No. 808,987 Claims priority, application Great Britain, Jan. 10, 1969, 1,673/69 lint. Cl. Clllm 1/38, 3/04, 5/10 US. Cl. 252--48.6 11 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention The invention is concerned with compositions useful in treating metal surfaces, particularly ferrous metals. It is especially concerned with oil compositions useful as coatings for protection of metal surfaces during storage and as lubricants during steel cold rolling operations.

As cold rolling lubricants, the compositions of this invention reduce gouging and scratching of the metal surfaces during cold rolling. They also are effective in providing clean surfaces following heat treatment, as in annealing processes. This latter property is believed to be due in part to any residual oil being burned off during annealing. The major factor, however, is the ability of the composition to effectively float metal fines, tamp oil and diet present in the emulsions used with the inventive compositions, thus eliminating the possibility of these being deposited on the rolled metal to contribute to discoloration after annealing.

Description of the prior art Various types of lubricant compositions have been used in metal working, as for example in cold rolling processes involving ferrous metals. For the most part, however, such compositions provide inadequate lubrication or cause objectionable surface discoloration or imperfections. In many instances, they are ineffective in preventing the formation of rust during processing.

The art has made several attempts to overcome the deficiencies of presently used lubricants. One such attempt is outlined in U.S. Pat. No. 3,298,954, which is directed to compositions containing polybutenes, fatty acids, and in some cases, sperm oil wax. US. 3,071,544 describes an emulsifiable oil which, in addition to its other stated advantages, is alleged to have the ability to provide a clean metal strip upon annealing of the metal after the rolling operation. Such oil comprises an emulsifier, a mineral lubricating oil, an alkali metal or alkanol-amine salt of petroleum sulfonic acids, an organic monocarboxylic acid, as for examples oleic and stearic, or an alkanol ester thereof, and an alkanolamine. The acid or the alkanolamine may be in slight excess.

It is not believed, however, that either of the justmentioned patents, or any art known, discloses the compositions of this invention, and particularly the advantages which are derived from their use.

It will be noted from the above art that mineral oilbased lubricants have been used almost exclusively in cold rolling steel, but suffered the disabilities mentioned in the first paragraph under this section, namely, inadequate lubrication and the forming of objectionable discoloration on the metal surface and the inability to prevent deposits upon annealing. The patentee in U.S. Pat. No. 3,071,544, in his attempt to overcome certain of these deficiencies, compounded a complex mixture of materials for use as an emulsion. In the second patent mentioned, US. 3,298,954, patentee used polybutencs as a substitute for mineral oils as his solution to the problems inherent in the use of mineral oil. While both of these compositions are no doubt effective for their intended purposes, they do have among others, the disadvantage of relatively higher cost.

While it is true that the requirements for metal working lubricants have recently become more stringent because of new alloys, demands for higher production rates, and the like, it is also true that the metal working industry is seeking improved lubricants which are economical for use in its operations. The composition of this invention has that advantage. Basically, the discovery herein is that the inexpensive mineral oil base can be used in a com position which overcomes the disadvantages of prior art mineral oil-based lubricants, when such lubricant contains a naturally occurring wax such as slack wax. The advantages of such a composition will become apparent from the remainder of this disclosure.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a lubricant composition comprising a liquid lubricant, especially a mineral lubricating oil, an acid or acid dervatives selected from the group consisting of an aliphatic monocarboxylic acid having from about 12 to about 26 carbon atoms, a polymer or a glyceride thereof and a wax, preferably a paraffin wax such as slack wax, which composition may have additionally present therein an agent for imparting additional load carrying properties thereto.

The composition is especially useful as a precoating for steel to prevent corrosion thereof during storage before rolling, to provide lubrication during coiling and uncoiling processes to prevent surface scratching and gouging, to provide lubrication during rolling in the first pass of a reversing mill or first stand of a tandem mill and to maintain the circulated mill coolant in a clear condition by floating fines, tamp oil and dirt to the surface in the reservoir of the circulation system.

DESCRIPTION OF SPECIFIC EMBODIMENTS The liquid lubricants used in this invention include naphthenic and paraffinic mineral oils having a kinematic viscosity in the range of from about. through about 350 S.U.S. at 100 F., as well as synthetic lubricants such as synthetic ester lubricants and alkylene oxide-derived fluids. This liquid lubricant is present in the amounts ranging from about 50% to about 90% by weight of the neat composition, and preferably from about 60% to about by weight.

From about 1% to about 10% by weight of the composition is an aliphatic monocarboxylic acid having from about 12 to about 26 carbon atoms or a polymer or glyceride thereof. This range includes lauric, myristic, palmitic and stearic acids, which are normally solid at room temperature and normally insoluble in mineral oils and water. Preferably the saturated acids are employed, and the more preferred one is hydrogenated tallow fatty acid. Also included are other designated fatty acids such as soya bean fatty acid. No great problems have been encountered, nor are any contemplated which cannot be overcome in their use since at elevated mixing temperatures and at mill operating conditions these acids, polymers and glycerides may become liquified and miscible with the mineral oil, while at low temperatures the paraffin wax present solidifies and maintains the solid fat in a stable suspension. For application to the metal surface, the composition must be heated to such a temperature that the wax/oil/fat mixture becomes liquified to ensure a uniform coating on the metal surface; under these conditions a homogeneous mixture is maintained.

The lubricant composition contains from about to about 15% by weight of a wax, such as slack wax, i.e., a. light neutral wax obtained by dewaxing the oil fraction to crystallize the higher melting hydrocarbons present therein and pressing, filtering or centrifuging to separate the oil fraction. An example of such a wax is one containing about oil, having a M.P. of 50 C., and having a viscosity of 38.5 S.U.S. at 210 F. In the lubricant composition of the present invention, this so-called slack wax is the preferred wax. Useful compositions may be achieved by using a lesser quantity of another wax, such as beeswax or another paraffin wax, of similar molecular weight distribution, although such a composition may be more expensive. At the present time, it is believed that waxes of higher molecular weights may give rise to annealing problems due to the inability to remove them prior to annealing operations.

The lubricant composition may also contain from about 0.5% to about 25% by weight of an agent for imparting load carrying characteristics thereto. Preferably a sulfurized mineral oil, such as a solvent refined 150 S.U.S. 100 F. paraffin oil containing about 0.6% by Weight of dissolved sulfur. Such load carrying (or E.P.) agents are well known to the art. However, it may be mentioned that other sulfurized fats and oils, as well as many other sulfur-containing compounds may be used. In addition, phosphates and phosphites, such as his (nonylphenyl) phosphite, are also useful.

The function of a load carrying, or E.P., agent is to provide increased protection against gouging and scratching in the processing of metals, as in coiling and uncoiling operations. In rolling processes, this has only comparatively recently become a problem, since heretofore the weight of the metal coils was not suflicient to introduce appreciable metal to metal contact with currently used precoat lubricants.

However, with the advent of larger and more powerful equipment for handling metal coils, large coil weights are becoming more common. With such high weights, lubricant compositions used in metal rolling operations must protect the metal surfaces from scratching and gouging, and the inventive compositions serve to reduce both.

Having discussed the invention in general terms, the following will show how the lubricants are prepared and utilized.

Lubricant compositions were prepared using the following substances:

Parts by weight Mineral oil 81 Hydrogenated tallow fatty acids 4 Slack Wax Mineral oil 61 Hydrogenated tallow fatty acids 4 Slack wax l5 Sulfurized mineral oil The mineral oil is a naphthenic oil having a viscosity of 300 S.U.S. at 100 F.

The hydrogenated tallow fatty acid is a commercial grade tallow acid containing from 1 to 3% myristic acid, 23 to 33% palmitic acid and 65 to 77% stearic acid.

Number Weight Acid of carbons percent M yristic l4 3. 0 Palmitic- 16 23. l Palmitoleic. l6 3. 0 Stearie l8 l8. 1 ()leie 18 38. 0 Linoleic 18 4. 5

Unidentified l0. 3

Total 100. 0

The final composition had the following approximate analysis:

(III) Parts by volume Mineral oil Fatty matter 15 A commercially available emulsion was used in connection with the cold rolling operations of Examples 3 and 4. This emulsion is constituted substantially as follows: 97-98% water and 23% of a composition comprising 70% of a mineral and 30% of a fatty material containing an amine as emulsifier plus a small amount of non-ionic emulsifier. The neat composition has a viscosity of 51 cs. at 100 F. and a saponification number of 60.

The substances comprising the composition of this invention may be mixed in any convenient order. Since the product is normally a solid at ambient temperatures, adequate mixing may be accomplished by applying heat to the mixing chamber. A temperature just above the melting point of the highest melting component is sufficient for this purpose.

EXAMPLE 1 Comparative anti-rust properties Two tests were used. One was the standard Salt Spray test; the other was the so-called QCT Cabinet test.

Salt Spray Test.Steel test panels were coated with the various compositions and were hung in a spray cabinet maintained at F. and the panels were sprayed With a 3% aqueous sodium chloride solution for 5 minutes in each hour for the duration of the test. Times given in the table below indicate interval before first rust spot appeared.

QCT Cabinet Test.A cabinet is constructed so that the base and sides make up the reservoir for the water and the roof is made up from the various test panels. In this test, water was placed in the reservoir or tank and was heated to F. Steel panels were coated on one side and were hung to form a roof over the tank. In this manner, water was allowed to condense on the treated side. The results in the following table show the times required for the first rust spots to appear.

From the above data, it is evident that it requires a longer time for rust spots to appear in either the QCT Ca'binet Test or in the salt spray test when using Composition I and II. The results obtained in the Cabinet Test 6 show significant improvements with these two composicleanliness of the annealed strip was rated as medium tions compared to Composition III. The Salt Spray Test, or normal, i.e., the scotch tape had picked up very few however, indicates an even more significant suppression particles. Three days following the substitution of Comof corrosion, in that rusting is suppressed for from about position -I, the cleanliness of the annealed strip was rated 3 to about 6 times longer than when using Composition 5 as excellent, the scotch tape being virtually free of ad- III. hering particles.

EXAMPLE 2 Following the end of the test with Composition I, Composition III was again used as the coating. After two days, the annealed strip was again as dirty as it had been The test used was the well-known 4-Ball Test. The 10 t th t t f th t t with Composition III, following results were obtained by running the test for Comparative E.P. proper-ties 1 minute at 1800 r.p.m. EXAMPLE 4 SCAR DIAMETER AND WELD Comparative flotation effectiveness Composition The cleanliness shown by the use of Composition I i attributable, in large measure, to its ability to aid in floating the fine particles of metal, impurities and the like present in the emulsion. This allows easy removal of such particles, as by skimming or decanting. In this way, it is possible to remove from the emulsion those foreign substances which tend to adhere to the metal and which as a The result? 9 thls example estahhsh lifi of luhn' consequence produce dirty surfacesiii subsequent processcant compositions exemplified by Composition II as ing of the metaL having E.P. properties. Composition I, which contains AS is Shown by the f ll i data Compared to c th Sa Substances a8 COmPOSIhOII II except the position III (first day), Composition I (last day) provides Slllfllriled Oil, s no appreciable P p Since skimming material having higher iron content and allows welding occurred at the lowest 100 kg. load. Composition lower i Content in emulsion, in Spite of the i 1H fails at 200 kg., and Composition II does not fail crease in the emulsion strength over the period of the until the load reaches 250 kg. test.

ANALYSIS OF THE CONVENTIONAL EMULSION First day of trial using Coni- Last day of trial using Composition III as coating position I as coating Skirnming materials Emulsion skimming materials Emulsion glen content, p.p.m 3 8 6, 200 no Emhis idns tihgth;h h '2 I:II IIIIIIIIIIIII On the first day of the trial Composition III was bein EXAMPLE 3 r a e0 used; Composition I was in use on the last (third) day of Comparative cleanliness of annealed strips the trial l h the product may be applied to the Surface The results established the fact that Composition I is of the metal in any convenient way, as by brushing and a Superior hofatlml ag nt. the like, it is preferable in large scale treatment to use a so far h 15 known, Q other D -Coat oil is also useful circulating System as was done in this embodiment as a flota tion agent. While the combination of acid and The lubricant compositions (Compositions I and III) Wh rhlheral 0111s h hf essehtlal for g Q h i were applied to a low carbon Steel Strip having a thick it is believed that the ingredient most responsible is the ness of from 1.8 to 5 min. by means of a circulating It 15 known that temperature P y nd po taht system consisting essentially of a reservoir heated by role, both 111 the P P h 0 e omposition and in electrical resistance to a temperature of between R the temperature of the emulsion used in rolling operations.

and 1140 F, a pump lines ,(heated the Same With regard to the temperature of preparation, it must perature) for dripping the product on both sides of the be Sufficlenfly hlgh to melt the acld, Its Polymer glyc ship, a Steel roll for distribution and a return line for eride so this ingredient can become distributed uniformly returning the excess to the reservoir. throughout the blend. Obviously then, the temperature The metal strip was passed from 3 to 5 times, accorddunng preparafloh f the o position rnust he at least ing to Width, through a production scale Single above the melting points of the acid or acid derivative and stand 4-high reversing mill at a maximum speed of about the W In the blehd' h a homogeneous mlxthre 650 mjmim The final thickness was 03 to 25 mm As obtained, wait and/or acid will tend to separate, thus in previously indicated, a conventional emulsion at a temefiect destroymg the fiotahoh Properhes of the Comphsl perature of 113 F. Was used.

The coils were annealed in a cracked gas (i.e., a mix- 60 Pnor art coatmgs contammg no emulslfiers when I h d one 11 O to 95 h Washed oil? the metal strip by an emulsion, tend to float $22 i fg agg s ssiz g g at 3 30 to the surface of the emulsion, but do not carry with them (8000 C), and, after annealing, the cleanliness of the a significant amount of fines, or not enough to prevent dirty surfaces upon annealing of the metal. The inventive compositions are also washed oif the surfaces during rolling operations and they float to the surface of said emulsion. In contrast, however, most of the fines are carstrip was determined on a skin pass mill using the scotch tape method. In this method, a piece of scotch tape is applied to the strip surface and transferred to clean white paper to provide a permanent record of the amount of loose dirt adhering to, the Strip Surface ried along, and these can be easily skimmed or decanted, The initial strip was obtained from. coils which had thus phevehhhg hh h h metal ShrfaCebeen coated with Composition III. After annealing and The lhvehhve Composlhons Contalmhg Wax and held passing through the skin pass mill, the coil was dirty, as its derivatives, and which y also Contain a load indicated by the many particles adhering to the scotch carry g agent, work Well as flotation agents at u si n tape temperatures used for best results in metal rolling. Gen- Subsequent strips were obtained following a changeerally, the lower end of the temperature range is between over to Composition I. On the first days operation, the about F. and F. Also, such temperatures usual- 7 1y range up to 140 F. to 150 F., but the preferred temperature is between about 110 F. and 120 F. The compositions of this invention are operative as flotation agents within this range so long as there is a sufiicient amount of the composition present in the emulsion to cause flotation of the fines.

Taken as a whole, the above tests involving the compositions of this invention show that the inventive lubricants are indeed exceptional. They are compounded of simple and readily available materials, thus providing inexpensive lubricants to the art. Depending upon the composition selected, they provide (1) greater protection against rusting of metal surfaces, (2) lubricants having good E.P. properties, (3) metal surfaces which are clean and clear of foreign matter, and (4) compositions which are excellent floating agents for fines which are present in the emulsions used in metal rolling. All in all, the results show the discovery of compositions which could not have been discerned from the presently known art.

What is claimed is:

1. A lubricant composition comprising (a) at least 50% of a mineral lubricating oil; (b) about 1 to of an aliphatic monocarboxylic acid having from about 12 to about 26 carbon atoms or a derivative thereof selected from the group consisting of polymers and glycerides; and (c) about 5 to 15% of a wax selected from the group consisting of paraflin wax and beeswax.

2. The composition of claim 1 which has therein an agent for imparting load carrying properties thereto.

3. The composition of claim 1 wherein said wax is slack wax.

4. The composition as defined in claim 1 wherein the acid derivative is hydrogenated tallow fatty acid.

, 5. The composition as defined in claim 1 wherein the wax is parafiin wax.

6. The composition of claim 1 wherein said lubricating oil is present in an amount of from about to about by weight.

7. The composition of claim 6 which has therein from about 0.5% to about 25% by weight of an agent for imparting load carrying properties thereto.

8. The composition of claim 7 wherein the said agent is a sulfurized mineral oil.

9. The composition as defined in claim 7 wherein the acid derivative is hydrogenated tallow fatty acid,

10. The composition as defined in claim 7 wherein the wax is paraffin wax.

11. The composition as defined in claim 7 wherein the wax is slack wax.

References Cited UNITED STATES PATENTS 2,126,128 8/1938 Montgomery 25256 2,167,439 7/1939 Kaufman 252-48.6 2,206,152 7/1940 Bennett 260-402.5 3,031,749 5/ 1962 Adams 252-49.5 3,298,954 1/1967 Brown 252-59 DANIEL E. WYMAN, Primary Examiner W. H. CANNON, Assistant Examiner U.S. Cl. X.R. 252-495, 56