US3428565A - Lubricating compositions - Google Patents

Description

United States Patent Ofice 3,428,565 Patented Feb. 18, 1969 3,428,565 LUBRICATINGCOMPOSITIONS Robert L. Fischer, Trenton, N.J., assignor to Cities Service Oil Company, Bartlesville, Okla., a corporation of Delaware No Drawing. Filed Feb. 24, 1966, Ser. No. 529,625 U.S. Cl. 25259 12 Claims Int. Cl. C10m 5/10, 5/06 ABSTRACT OF THE DISCLOSURE Wire rope lubricating composition comprising 40 to 75% mineral oil, 20 to 50 wt. percent micro-crystalline wax and 0.1 to 20 wt. percent of a relatively crystalline poly-l-alkylene, such as polyethylene, having an average molecular weight of 5,000 to 100,000. The composition rnay contain other ingredients, such as anti-Wear agents, extreme pressure additives, antiarust additives or wetting agents and may be formed by mixing the ingredients together at temperatures of about 300 F. for a sufiicint time to provide a fluid, homogeneous composition. The blended composition may be applied by conventional techniques, such as dripping, spraying or brushing and is preferably applied to the individual wires before they are closed into strands.

The invention relates to protective lubricating compositions. In more particular respects, the invention relates to lubricating compositions especially useful in the lubrication of wire ropes, as well as to wire ropes lu'bri cated with such compositions.

Lubricating compositions play an extremely important role in producing a wire rope to give satisfactory service in the field. As an example, a wire rope must be capable of withstanding the tremendous stresses, including tension, compression, torsion, shear, and fatigue, which are imposed on a rope while operating over and around a sheave or drum. A satisfactory lubricant must, therefore, reduce and equalize the friction and stress in the wire rope. In addition, it is important that the lubricating composition have a strong affinity for the wire rope and not drop-off, wipe-01f or throw-0E by centrifugal force when the rope is operated around a sheave at high speeds. The ability of the lubricant to resist throwoff from the rope at high speeds and high temperatures is a particularly important consideration in oil Well drilling rig equipment and other high speed equipment. Furthermore, the lubricant must not flake-oil the rop at low temperatures.

Heretofore, asphaltic compounds have been used to lubricate wire ropes. These asphaltic lubricants generally leave much to be desired as regards their ability to adhere to the wire rope to prevent throw-01f by centrifugal force at high speeds. In addition, the asphaltic compositions are objectionable from the standpoint that they are messy to handle.

My present invention provides novel lubricating compositions which when applied to wire ropes or similar metallic articles form a flexible, strongly adhesive, and generally transparent protective coating. 'The transparent nature of the lubricating composition renders it more acceptable than substantially asphaltic compositions from a customers standpoint because of ease in handling and clean-up. Furthermore, the transparency of the lubricant coating enables defects in the rope to be readily detected. Additional advantageous characteristics of the lubricants are that they do not flake-off the wire rope at low temperatures, or fiy-oif from the rope at high temperatures when the rope is operated about a sheave or drum at high speeds. Furthermore, the lubricity imparted by my compositions to a wire rope is at least substantially equivalent to the lubricity imparted by asphaltic compositions heretofore used for this purpose. Various other advantages and objects of the invention will be apparent to those skilled in the art from the following detailed description thereof.

Broadly, the lubricating compositions provided by my present invention comprise certain amounts of mineral oil, microcrystalline wax and a poly-l-alkylene resin having a crystallinity of at least about 40% and a number average molecular weight of from about 5,000 to about 100,000, in homogeneous admixture. More particularly, the present lubricating compositions comprise from about 40% to about by weight mineral oil, from about 20% to about 50% by Weight microcrystalline wax and from about 0.1 to about 20% by weight of the poly-l-alkylene resin.

The oil component of the lubricating composition may be any mineral oil, including such materials as 100 and 200 Neutral Oils, light and heavy intermediate mineral oils, bright stocks, cylinder stocks, as Well as combinations of the foregoing. The viscosity of the mineral oil is not a particularly important consideration in the practice of the present invention.

The microcrystalline wax component is a relatively high molecular weight petroleum wax characterized by the relative fineness of its crystals in distinction to the larger crystals of parafiin wax. Miorocrystalline waxes have an average molecular size of from about 50 to about 100 carbon atoms, and consist predominantly of branched-chain saturated paraflinic and cycloparafiinic hydrocarbons with a significantly lesser amount of normal-parafiinic hydrocarbons and a minor amount of aromatic hydrocarbons. The microcrystalline wax employed in the composition may be crude or refined. The melting point of the microcrystalline wax may suitably range from about 140 F. to about 210 F.

The poly-l-alkylene employed in the practice of the invention may be a polyethylene, polypropylene or other l-alkylene homopolymer or copolymer having a number average molecular weight of from about 5,000 to about 100,000 and a crystallinity of at least 40%. As is Well-known in the art, the degree of crystallinity of a polymer may be determined by X-ray analysis or other analytical tests commonly used for this purpose, such as infrared methods. In general, polyethylenes show a percent crystallinity ranging from about 40% to about 95% by X-ray analysis, while isotactic polypropylene shows a percent crystallinity of from about 60% to about or higher. Amorphous (atactic) polypropylene has little or no crystallinity. The preferred poly-l-alkylene for the purpose of this invention is polyethylene, and particularly polyethylene having a number average molecular weight of from about 7,000 to 60,000 and a percent crystallinity of from about 50% to about 80%. Such preferred polyethylenes will also have a low-to-intermediate density (e.g., 0.91 to 0.94 g./cc.).

The mineral oil and microcrystalline wax may be separately added in preparing the lubricating composition. Alternatively, a suitable amount of a petrolatum, such as one containing from about 5% to about 40% mineral oil from about 60% to about microcrystalline Wax, may be employed in lieu of or in conjunction with the mineral oil and microcrystalline Wax ingredients to obtain the desired amounts of these ingrediants in the composition. For example, the lubricating compositions of the present invention may comprise from about 1% to about 40%, preferably from about 10% to about 30%, petrolatum in addition to mineral oil, microcrystalline wax and poly-l-alkylene resin, the

3 total amount of mineral oil in the composition being from about 40% to about 75% by weight and the total amount of microcrystalline wax being from about to about 50% by weight.

I have found that particularly outstanding wire rope lubricants are obtained by adjusting the amounts of polyl-alkylene, microcrystalline wax, mineral oil, and petroleum, if employed, within the ranges noted above to provide a composition having a cone penetration (ASTM D937) of from about 20 to about 300 decimillimeters at 77 F., preferably 60 to 130 decimillimeters, and a melting point of from about 140 F. to about 225 F. (ASTM Dl27), preferably 160 F. to 205 F. For this purpose, it is preferred that the total amount of mineral oil in the composition range from about 50% to about 70%, while the total amount of microcrystalline wax range from about 30% to about 45%. It has further been found that although the amount of poly-l-alkylene in the lubricant may range up to about 20% or higher, additional benefits as regards the ability of the composition to adhere to the wire rope when the rope is operated at high speeds about a sheave do not generally accrue from using poly-l-alkylene concentrations greater than about 10% by weight. Accordingly, outstanding results may be obtained by employing from about 0.2% toabout 10% poly-l-alkylene, particularly from about 0.25% to about 6% poly-l-alkylene.

It is often desirable to incorporate in the lubricating composition a suitable amount of one or more additional ingredients, for example, anti-wear agents, extreme pressure additives, and anti-rust additives, wetting agents, etc. Such additives and their functions in petroleum compositions are Well-known in the art. Illustrative of various additives which may be incorporated in the composition to provide improved anti-rust, anti-wear and/or extreme pressure characteristics thereto are phosphorus-containing organic compounds, sulfur-containing organic compounds, halogen-containing organic componds, naphthenates, sulfonates, etc. Specific compounds are, for example, hydrocarbyl phosphates, such as tri-cresyl phosphate; metal hydrocarbyl phosphates, such as titanium tetra- [bis(2-ethylhexyl)orthophosphate], manganese di[bis- (octyl)orthophosphate], and the adduct of cocoamine and titanium tetra[monoacid, mono(2-ethylhexyl)orthophosphate]; halometal hydrocarbyl phosphates, such as dichloromolybdenum tri[bis(2 ethylhexyl)orthophosphate]; hydrocarbyl thiophosphates, such as dioctyl dithiophosphoric acid; metal hydrocarbyl thiophosphates, such as antimony tri[bis(isodecyl)dithiophosphate]; lead di[bis(hexyl)dithiophosphate], and titanium tetra[bis(2- (ethylhexyl)dithiophosphate]; metal hydrocarbyl thiocarbamates, such as lead diamyldithiocarbamate and cadmium diamyldithiocarbamate; metal naphthenates, such as lead naphthenate; and metal sulfonates, such as sodium dinonylnaphthelene sulfonate, lead dinonylnaphthelene sulfonate, barium dinonylnaphthelene sulfonate and calcium dinonylnaphthelene sulfonate. The composition may also contain various wetting agents, for example, those of amine type or fish oil, to promote wetting of the individual wires or strands of the rope with the lubricant.

It is within the skill of the art to select the best additive or additives and amounts thereof to obtain the desired improvements in one or more properties of the composition, and, accordingly, it is not desired to limit the invention to the specific additives noted-above. If additives are used, they should, of course, be compatible with the lubricating composition.

The lubricating composition may be prepared by a number of suitable procedures. For example, the mineral oil, microcrystalline wax, poly-l-alkylene and petrolatum, if employed, may be mixed together at an elevated temperature for a sufiicient time to provide a fluid homogenous composition. Ill-ustratively, temperatures on the order of 275 F to about 400 F. have been successfully employed in this blending operation. If it is desired to incorporate extreme pressure, anti-wear or other types of additives in the lubricating composition, they may be added simultaneously with or following blending of the other ingredients. Ordinarily, however, it is preferred to blend the wax, oil and poly-l-alkylene at a relatively high temperature which will permit reasonably rapid formation of a homogenous fluid mixture, e.g. 275 F. to about 375 F., and thereafter incorporate the extreme-pressure agents and/or other additives in this homogenous fluid at a somewhat lower temperature, for example, 210 F. to 250 F. This practice maximizes the rate of homogenization of the wax, oil and poly-l-alkylene, while minimizing s of the additives, many of which are of a somewhat volatile nature. In the case of poly-l-alkylenes having a relatively higher degree of crystallinity, and hence requiring higher tempertures for homogenization, it may be desiar-ble to blend the oil and the poly-l-alkylene at a relatively high temperature and add the wax and petrolatum after cooling the resultant blend to prevent excessive oxidation of the wax.

The blended lubricating composition may be applied to the wire rope utilizing conventional industry procedures. For example, the lubricating composition may be dissolved in a suitable readily-vaporizable solvent or melted and applied to the exterior of the rope by a dripping, spraying or brushing operation. It is more desirable, however, to apply the lubricant in a molten state to the individual wires as they are laid up at the stranding machine used in wire rope manufacture. For example, the molten lubricant may be sprayed, poured or brushed onto the individual wires before they are helically closed into the strand. It is also feasible to apply the lubricant or additional amounts of the lubricant in that part of the wire rope manufacturing process where the strands are closed about a core to form the finished rope. In addition, lubricant may be applied to the core itself, e.g. a hemp core, on the closing machine, whereby some of the lubricant will be squeezed from the core onto the metallic phase of the rope when the strand is closed about the core.

Upon cooling, the lubricating composition forms a protective, strongly adhesive, generally transparent film on the wire rope, which effectively reduces friction between the wires and strands of the rope.

It should be noted that the particular type of wire rope construction is not a critical feature of this invention. Thus, many special types of wire ropes are known in the art which differ from each other in the number of strands laid around the core, the number of wires in each strand, wire arrangement, direction of lay of the strands, steel grade, core construction, etc. My lubricating compositions are effective in lubricating wire ropes of any construction.

The invention will now be further described with reference to the following specific examples which are presented solely for the purpose of illustration and are not to be interpreted as limiting the scope of the invention.

Example 1 About 530 grams of a No. 6 cylinder stock (SUS vis. 210 F. of 200) and 20 grams of a commercial polyethylene having a density of 23 C. of 0.922, a number average molecular weight of 30,000 and being of intermediate crystallinity (about 65%) are heated with stirring at a temperature of about 360 F. for a period of about 40 minutes until all of the polyethylene is dissolved. Solution of the polyethylene can be determined by momentarily stopping the stirrer whereby any polyethylene not in solution will float to the surface of the oil. After the polyethylene has been dissolved in the oil, grams of a crude microcrystalline wax having a melting point of 174 F. and a needle penetration at 77 F. of 45 decimillimeters, and 220 grams of a petrolatum having an oil content of 20% and a microcrystalline wax content of 80%, a melting point of 148 F. and a needle penetration at 77 F. of 75 decimillimeters are added to the homogenous fluid mixture with continued stirring. The temperature of the resultant homogenous blend is then reduced to about 230 F., and 20 grams of fish oil and grams of an amine wetting agent are added along with 20 grams of a mixture of 32% of an organic lead sulfur compound, 38% of lead dinonylnaphthalene sultonate and 30% of antimony phosphorodithioate to impartpimproved extreme pressure, rust-preventative and anti-wear characteristics to the composition. The blended composition is poured from the mixing vessel at a temperature of 205 F., cooled and tested to determine its properties, the results being as follows:

TABLE 1 Color brown Cone penetration (ASTM D-937) decimillimeters 90 Melting point (ASTM D-l27) F 201 Shell 4-ball EP test:

Weld point kg 230 Means Hertz load 43 Modified Timken.O.K.,load 1 (4 g.; 10 min.) lbs 25 Cleveland open cup flash point F. min 510 Cleveland open cup fire point F. min 630 Viscosity, SUS 210 F. 238 Specific gravity 0.905 Ring and ball softening pt. (ASTM D-36) l40.5 Oxidation stability (ASTM D-942) Pressure drop after 100 hours psi 7.0 Pressure drop after 200 hours psi 14.0

Test described in U.S. Steel Lubrication Engineers Manual, page DM49, March 1965, published by U.S. Steel Company.

To test the usefulness of the composition as a wire rope lubricant, the composition is melted at a temperature of about 230 F. and sprayed onto the individual wires before they are closed into strands. The lubricant solidi fies rapidly on the wires forming a transparent ambercolored protective film. T-he film coating does not peel ofi the rope even when the rope is flexed at a temperature of 20 F.

The high temperature behavior of the lubricant is determined by the ,Sheave Drip Test which is used to evaluate lubricants for use on rotaty drill cables. In accordance with this test, a 12-inch diameter sheave having a groove of %-inch is mounted vertically on a horizontal motor shaft. About a 3-inch section of the sheave groove is packed with the lubricating composition prepared as described above, and the top surface of the lubricant packing is leveled-off with a spatula. For purposes of control, an asphaltic composition heretofore used commercially as a wire rope lubricant is placed in another 3-inch section of the sheave groove in the same manner. The sheave is encased in a closed chamber provided with a glass side to permit visual observation of the release of the lubricant from the groove. Observation of release of the lubricant is aided by placing a white sheet of paper on the bottom of the enclosing chamber. The temperature of the chamber is regulated by means of two high wattage light bulbs and is measured by a thermometer extending into the chamber near the circumference of the sheave. In conducting the test, the sheave containing the lubricants is rotated at a speed of 160 r.p.m. The two light bulbs are turned on to raise the temperature within the chamber to about 90 F. to 100 F. At this point, one bulb is turned-off so that the temperature within the chamber will increase relatively slowly thereafter. The temperatures at which the respective lubricants drop from the sheave are necorded.

The lubricant prepared in accordance with the present invention drops from the sheave at a temperature of 127 F., while the asphaltic composition heretofore widely used as a wire rope lubricant drops at only 110 F.

6 Example 2 A lubricating composition is prepared as in Example 1, except that the cylinder stock is employed in the amount of 500 grams and the polyethylene is employed in the amount of 50 grams. The composition is characterized by a cone penetration of 75 decimillimeters, a melting point of 208 F. and a viscosity (SUS 210 F.) of 958. The composition is a suitable wire rope lubricant.

Example 3 A lubricating composition is prepared as in Example 1, except that the cylinder stock is employed in the amount of 540 grams and the polyethylene is employed in the amount of 10 grams. The composition is characterized by a cone penetration of decimillimeters, a melting point of 193 F. and a viscosity (SUS 210 F.) of 165. The composition is a suitable wire rope lubricant.

Example 4 For comparative purposes, a composition containing amorphous polypropylene instead of the relatively crystalline poly-l-alkylenes used in the practice of the invention is prepared according to the following formulation:

Mixture of 32% organic lead sulfur compound; 38% lead dinonylnaphthalene sulfonate; 30% antimony phosphorodithioate 2 When subjected to the previously-described Sheave Drip Test, the composition does not perform as well as the asphaltic lubricant control, and is decidedly inferior compared to the polyethylene-containing lubricant of Example 1.

While the invention has been described above with respect to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended to cover all such changes and modifications in the appended claims. For instance, a minor amount of ahphalt may be added to the composition without seriously decreasing the ability of the lubricant to adhere to the wire rope at high temperatures and speeds. However, the employment of asphalt in the composition would, of course, be objectionable when a generally transparent lubricant coating is desired. Accordingly, the preferred gompositions of the invention are substantially asphaltree.

Therefore, I claim:

1. A lubricating composition comprising from about 40% to about 75% by weight mineral oil, from about 20% to about 50% by weight microcrystalline wax and from about 0.1% to about 20% by weight of a poly-lalkylene having a number average molecular weight of from about 5,000 to about 100,000 and a percent crystallinity of at least about 40%, said lubricating composition having a cone penetration of from about 20 to about 300 decimillimeters at 77 F. and a melting point of from about F. to about 225 F.

2. A lubricating composition as in claim 1 wherein said mineral oil is present in an amount of from about 50% to about 70% by Weight, and said microcrystalline wax is present in an amount of from about 30% to about 45% by Weight.

3. A lubricating composition as in claim 2 wherein said poly-l-alkylene is present in an amount of from about 0.2% to about 10% by weight.

4. A lubricating composition as in claim 1 wherein said poly-l-alkylene is polyethylene.

5. A lubricating composition as in claim 4 wherein said polyethylene has a percent crystallinity of from about 50% to about 80% and a number average molecular weight of from about 7,000 to about 60,000.

6. A lubricating composition as in claim 1 which further comprises from about 1% to about 45% by weight petrolatum.

7. A wire rope lubricated with a composition comprising from about 40% to about 75% by weight mineral oil, from about 20% to about 50% by weight microcrystalline wax, and from about 0.1% to about 20% by weight of a poly-l-alkylene having a number average molecular weight of from about 5,000 to about 100,000 and a percent crystallinity of at least about 40%, said lubricating composition having a cone penetration of from about 20 to about 300 decimillirneters and a melting point of from about 140 F. to about 225 F,

8. Lubricated wire rope as in claim 7 wherein said mineral oil is present in said lubricating composition in an amount of from about 50% to about 70% by weight, and said microcrystalline wax is present in an amount of from about 30% to about 45% by weight.

9. Lubricated wire rope as in claim 8 wherein said poly-l-alkylene present in said lubricating composition 8 in an amount of from about 0.2% to about 10% by weight.

10. Lubricated wire rope as in claim 7 wherein said poly-l-alkylene in said lubricating composition is polyethylene.

11. Lubricated wire rope as in claim 10 wherein said polyethylene has a percent crystallinity of from about to about and a number average molecular weight of from about 7,000 to about 60,000.

12. Lubricated wire rope as in claim 7 wherein said lubricating composition further comprises from about 1% to about 45% by weight petrolatum.

References Cited UNITED STATES PATENTS 2,211,254 8/1940 Chittick et a1 25228 2,350,571 6/1944 Schilling et al. 25259 2,762,775 9/1956 Foehr 25259 3,078,237 2/1963 Creech et al. 25259 3,080,330 2/1963 Rudel et al. 25259 3,175,972 3/1965 Mitacek et al. 25259 3,258,319 6/1966 Cox 25259 DANIEL E. WYMAN, Primary Examiner.

J. VAUGHN, Assistant Examiner.