MXPA98004667A - Solid lubricants and friction modifiers for heavy loads and ferroviar applications - Google Patents

Abstract

The present invention relates to new lubricant and friction modifier compositions optionally comprising a solid lubricant and a binder in an aqueous medium suitable for lubricating steel-steel interfaces such as tractor-trailer couplings, wheel-rail systems and other heavy duty applications. The invention also relates to compositions described above which include friction modifiers with high or very high and positive coefficients of friction such that the coefficient of friction is considerably higher than that of the solid lubricant. The invention also relates to compositions comprising a binder and a friction modifier with a very high and positive coefficient of friction in an aqueous medium.

Description

SOLID LUBRICANTS AND FRICTION MODIFIERS FOR HEAVY LOADS AND RAILWAY APPLICATIONS FIELD OF THE INVENTION The present invention relates to new compositions of lubricants and friction modifiers comprising a solid lubricant, or a friction modifier, or both, together with a binder in an aqueous medium, suitable for lubricating the steel interlining slides. steel such as tractor-trailer couplings, wheel-rail systems and other heavy-duty applications. The invention also relates to the compositions described above which include friction modifiers with high or very high positive friction coefficients such that the coefficient of friction is considerably higher than the solid lubricant. The invention further relates to compositions comprising a binder and a friction modifier with a positive and very high coefficient of friction in an aqueous medium.

BACKGROUND OF THE INVENTION Grease is a conventional lubricant for tractor-to-trailer couplings, wheel-rail systems and other heavy-duty applications. However, the grease has serious limitations for the operation and for environmental contamination. After joining the coupling components, after a grease application, a large portion of the grease is immediately lost due to the difficulties of the grease to adhere to the coupling or the rail. The lost fat falls on parts of the vehicle's pipeline and on the ground as a non-biodegradable contaminant. In addition, grease dissipates during use, causing its lubricating performance to deteriorate to potentially hazardous conditions. This known dissipation, in this way encourages users to apply excessive amounts of fat to compensate. In addition, the exposed couplings, the wheel rails can become contaminated with dust and sandstone, thus forming a grinding compound that causes rapid wear to the bearing plates unless cleaned and degreased before use. Typically, the fat is reapplied every week or every two weeks. Removal before red-lubrication is achieved with a high-pressure steam causing it to be flushed with the water supply. Alternatively, stronger solvents can be used to remove the grease which are even more unacceptable from the environmental point of view. Lubricating compositions comprising, inter alia, solid lubricants and polymer media have been used as alternatives to grease and these lubricants have the advantage of forming a film on the metal surface, and therefore, better adhesion. However, as the lubricant dissipates, the polymer medium can still contaminate the environment. Aqueous lubricant compositions have been suggested, but are discarded as impractical in the Swiss patent specification CH 669,207 A5, where a method for using an aqueous dispersion of graphite to coat or paint the sides of the rails is discussed and discarded since the aqueous dispersion is apparently removed easily. The solution of CH 669.207 A5 is a composition comprising inter alia, a polymer resin having the same disadvantages as the other polymer media as discussed above.

In US Patents Nos. 5,173,204 and 5,308,516 it is recognized that when the coefficient of friction increases with speed, it is known to have a negative friction characteristic. The origin of much noise emission in steel railway wheel transport systems can be directly attributed to the fact of the negative friction characteristic that under certain conditions appears in use, the wheels of these systems do not always roll on the rails but sometimes they slip in relation to them. This is more pronounced in the curves. An effective way to eliminate grinding and vibration is to change the friction characteristic from a negative to a positive one. Later, the term "positive friction" means that the coefficient of friction increases with the sliding speed and a coefficient of friction "high" is greater than 0.10 '. Apart from the reduced friction (and noise) and reduced wear of the wheels of the rails, the use of a friction modifier can prevent friction can prevent the initiation and development of short separation corrugation by preventing and eliminating Rotating movements, commonly known as roll-sensing oscillations, are caused at the rail / wheel interface in the presence of negative friction. US Patents Nos. 5,173,204 and 5,308,516 teach that in a rail-wheel system, the lubricant composition must be applied to 25% of all wheels in a wheel-rail system. Considering that the effect is more pronounced in the curves, a portion of lubricant, time and effort is required, in order to ensure that there is enough lubricant.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides lubricating compositions and water-based friction modifiers for heavy-duty use with metal applications such as tractor-trailer couplings or rail-wheel systems having characteristics of Improved adhesion. The inclusion of a binder, defined below, in the lubricant composition, or friction modifying lubricant, helps to bind the lubricant and the friction modifier to the coupling, rail, or other surface, therefore, the composition does not need to be applied as frequently or in the same amount and therefore there will be less lubricant and friction modifier lost and less environmental contamination. In another aspect, the invention also provides a lubricating composition based on water that includes a wetting agent. The inclusion of a wetting agent also helps to ensure that there is better adhesion of solid lubricant to the coupling, rail or other surface and in this way the solid lubricant can be better applied. This invention is also directed to compositions with water-based friction modifier that include a wetting agent. In another aspect, the invention also provides a water based lubricant composition that can be applied to a rail to precise areas identified as problem areas, such as curves or inclines. Due to this specific application in identified points, the subsequent transfer from the rail to the wheel means that the lubricant will extend along the rail by the movement of the wheels on the rail but mainly by the identified points. The advantages of this application by precision are that less lubricant, time and effort are required in order to achieve the same results of improved noise control, improved traction and reduced short separation corrugation. In yet a further aspect, the invention provides a lubricating composition that is easier to apply than the previous compositions. The lubricant composition is water based which makes it easier to apply since the binder absorbs the water present in the composition and thus allows rapid adhesion to the metal surface. In one aspect of this invention, the composition comprises: (a) at least about 24% by weight of the aqueous medium; (b) about 8% by weight of the binder; and (c) at least about 2% by weight solid lubricant. In another aspect, the lubricant composition further includes a friction modifier exhibiting high and positive, or very high and positive friction characteristics. The composition allows the solution to the oscillating sliding situation in the steel with steel described above with respect to the US Patents Nos. 5,173,204 and 5,308,516, above, but with the additional benefit of the application with precision described above, specifically, that will be required less lubricant, time and effort to achieve the same result stated in those patents. Accordingly, in a further aspect, the invention provides a lubricant composition comprising an aqueous medium, solid lubricant, binder and a friction modifier present such that the coefficient of friction produced between the steel bodies in the sliding motion with rolling , lubricated using these compositions is greater than 0.10 and wherein the coefficient of friction increases with an increase in the relative speed of the sliding movement between the bodies. According to a further aspect of the invention, there is provided a composition comprising: (a) at least 60% by weight of water; (b) at least 5% by weight of the binder; and (c) at least 3% by weight of the friction modifier; where the composition has the characteristics of a very high and positive friction, with a coefficient of friction that varies from 0.45 in a 2.5% of drag to 0.22 in 30% of drag. This product is mainly used to improve the traction of locomotion wheels. Additionally, according to the present invention there is a method to reduce the noise in a wheel system with steel rail by applying this composition of lubricant, or lubricant and friction modifier, the surface of the rail, whereby the composition Lubricant is effective to change the negative friction characteristics between the rail and the wheel to a positive friction characteristic. The present invention also provides compositions that are capable of effectively reducing short separation corrugation. This is achieved by compositions that have a high coefficient of friction and positive friction characteristics. The above compositions have the advantage of being relatively non-polluting and economical since the dispersion medium allows for the application in isolation to compositions to the target surfaces as the problem areas.

DETAILED DESCRIPTION OF THE SPECIFIC PROCEDURES OF THE INVENTION. In general, the lubricant and friction modifier compositions are water-based compositions consisting of water, a solid lubricant, as required, a binding agent, and in some embodiments, a friction modifier and / or a wetting agent. The lubricant and friction modifier compositions can be formulated by selecting one or more solid lubricants and friction modifiers as required. Examples of solid lubricants and friction modifiers can be found from, but are not limited to, the following lists.

Solid lubricants Molybdenum disulfide graphite aluminum stearate zinc stearate carbon compounds (coal dust, carbon fibers, etc.).

The preferred solid lubricants are molybdenum disulfide and graphite.

Friction modifiers calcium carbonate magnesium carbonate magnesium silicate barium sulfate calcium sulfate asbestos aluminum silicate silica silica amorphous silica naturally occurring slate dust diatomaceous earth quartz ground silica flour white lead carbonate basic oxide zinc antimony oxide dolomite calcium sulfite synamite naphthalene polyethylene mica The friction modifier, if any, preferably comprises a mineral powder. The friction modifier for a high and positive friction lubricant composition has a particle size in the range of about 0.5 microns to about 5 microns, and preferably has a particle size in the range of about 1 micron to about 2 microns. . A very high and positive friction modifier composition can have a particle size of 10 microns. The friction modifier r must have a coefficient of friction that is considerably higher than the coefficient of friction of solid lubricant. The values of the coefficient of friction are all those produced between the steel bodies in the sliding contact with rolling. The high and positive friction modifier compositions produce a coefficient of friction that is greater than 0.10 and where the coefficient of friction increases with an increase in the relative speed of the sliding movement between the steel bodies. For a very high and positive friction, the steel to steel friction coefficient for the lubricant composition according to the invention should be increased from about 0.45 to about 0.72 as the drag increases from about 2.5% to about 30%. The particular compositions contain friction modifiers but not solid lubricants to create very high and positive friction characteristics. The term "binding agent" herein is defined to mean a hydrophilic agent that absorbs water causing it to physically swell into particles in a manner capable of adhering to a rail. The binder creates a continuous phase matrix which is capable of binding the solid lubricants, friction modifiers of other compounds to a metal surface by dispersing the solid lubricant or retaining the solid lubricant in a discontinuous phase matrix. The binder has rigidity such that the composition is placed on the metal surface, has some structure and will maintain its integrity after the wheels go over the composition. Examples of binding agents include, but are not limited to, clays such as bentonite (sodium montmorillonite) and casin. . Optionally, preservatives, wetting agents and additives are also included to allow mixing of the composition with grease already in the rail or in the coupling. Preservatives such as ammonia are used to preserve the lubricant composition. Alcohols such as butoxyethanol may also be used . The term "wetting agent" used herein is defined to mean a flow agent that allows the solid lubricant particles to be surrounded by water within the matrix of the binder and the solid lubricant. The lubricating agent helps to reduce the surface tension and allows the solid lubricant to get into the grooves of the rails or other surfaces and also emulsifies the grease to allow a good adhesion. An example of a wetting agent includes, but is not limited to, nonyl phenoxypolyol.

Method of Preparation The embodiments of the lubricant and friction modifier compositions can be prepared according to the following method. Under a high speed mixer add slowly to 35% water in a mixing drum at room temperature, the binder (ie, bentonite (sodium montmorillonite)) and the wetting agent (ie, nonyl phenoxypolyol). These components should be mixed well until a thick gel forms. Continue mixing, then add the rest of the ingredients in the following order: water (the remaining 65%), ammonia, ether E.B. (if any), any of the other liquids, the solid lubricant (ie, molybdenum) as required, and any other solids. These components must be thoroughly mixed until a uniformity is assured that the solid lubricant is well dispersed. The resulting composition is a thick thixotropic liquid that is similar to jelly when it is at rest, but with shaking or buckling the viscosity decreases. The composition is a matrix whose continuous phase is the binder and which also contains a discontinuous phase, the solid lubricant.

The above compositions can be applied to the coupling of the surfaces of the rails or the like by means of which it will be recognized by one in the art such as pump or brush. The composition is applied so that a film of the composition is uniformly spread on the rail. The film is preferably a flange approximately one-eighth of a diameter in one inch in diameter. The binding agent works by absorbing the water in the composition. Over time, the composition dehydrates to leave a solid flange and thereby improve the adhesion of lubricant and friction modifier to the rail over previously used fats or polymer lubricant compositions. The binder further maintains the lubricant and the friction modifier uniformly dispersed after the wheel runs on the rail and also reduces water reabsorption. Therefore, the composition is not easily removed by rain. The desired level of friction coefficient for the compositions of this invention is obtained by proportionally mixing appropriate amounts and friction modifiers with a high coefficient of friction and solid lubricant with a very low coefficient of friction. The solid lubricant and the friction modifier are preferably present in the composition in approximately equal amounts for high and positive friction compositions but may be present in different amounts or without solid lubricant in order to achieve very high and positive friction characteristics. The following, given by way of example only and is not intended to be construed in a limiting manner, illustrates the compositions in accordance with the embodiments of the invention.

EXAMPLE 1 A composition of high and positive friction lubricant, based on water, comprises: (a) 80.193% by weight of water; (b) 8.940% by weight of sodium montmorillonite; (c) 0.004% by weight ammonia; (d) 0.002% by weight of nonyl-phenoxypolyol; (e) 4,930 wt. molybdenum disulfide; and (f) 4.93% by weight of magnesium silicate; and are prepared as described above. A heavy duty railroad from North America tested the previous composition and found that the noise levels were reduced by 20 decibels at the top of the rail and on the surface of the gauge. Similar lubricant compositions can be formulated by selecting one or more alternative lubricants and alternative friction modifiers as described above.

EXAMPLE 2 A very high and positive friction composition was prepared, based on water (without added lubricant) as described above using the following components: (a) 85.254% by weight of water; (b) 9,450% by weight of sodium montmorillonite; (c) 0.004% by weight ammonia; (d) 0.002% by weight of nonyl phenoxypolyol; (e) 5.20% by weight of anhydrous aluminum silicate; and (f) 0.09% by weight of black iron oxide (as a dye). The composition was tested and found to produce a positive steel to steel friction characteristic in the range of 0 to 0.45 as the relative slip velocity (drag) increased from zero to about 2.5%, increasing to approximately 0.72 as the drag it increased to approximately 30%. These coefficient of friction levels are substantially above steel-to-steel coefficient of friction levels obtained with conventional lubricants and above those of the lubricant composition described in US Patents Nos. 5,173,204 and 5,308,516.

EXAMPLE 3 A lubricating composition for the 5th wheel, based on water, was prepared as described above using the following components: (a) 58.994% by weight of water; (b) 8% by weight of sodium montmorillonite; (c) 0.004% by weight ammonia; (d) 0.002% by weight of nonyl-phenoxypolyol; (e) 3% by weight of butoxyethanol; Y . (f) 30% by weight of molybdenum disulfide. When lubricant was applied to the tread surface of a wheel, the composition showed marked improvement with respect to the addition of the lubricant. Tests have shown that the fifth wheel composition lasted substantially longer or substantially more miles, in the order of 5-10 times longer than conventional lubricants.

EXAMPLE 4 A lubricating composition with a low coefficient of friction, based on water, was prepared as described above, using the following components: (a) 79.502% by weight of water; (b) 12,621% by weight of sodium montmorillonite; (c) 0.004% by weight of ammonia; (d) 0.002% by weight of nonyl phenoxypolyol; (e) 3% by weight of butoxyethanol; and (f) 4.871% by weight of molybdenum disulfide. The test similar to that described in Example 1 was performed and with similar results that were recorded. It is understood that the invention has been described herein in conjunction with certain examples and embodiments. However, these changes, • Modifications or equivalents as may be used by those skilled in the art are proposed to be included. Accordingly, the description is to be considered as an example, rather than a limitation, and these changes are within the principles of the invention as are obvious to a person skilled in the art, and are intended to be included within the scope of the invention. claims.

Claims (27)

1. A water-based lubricant composition for lubricating steel-to-steel interfaces, comprising: (a) at least about 24% by weight of water; (b) about 8% by weight of the binder; and (c) at least about 2% by weight of solid lubricant, wherein a coefficient of friction is produced which increases with the increased levels of drag between the steel bodies in the sliding contact with rolling, lubricated using this composition.

2. The composition according to claim 1, wherein the composition comprises: (a) 24% -88% by weight of water; (b) 3-15% by weight of the binder; and (c) 2-60% by weight of solid lubricant.

3. A water-based lubricant composition for lubricating steels of steel, comprising: (a) at least 24% by weight of water; (b) about 8% by weight of the binder; (c) at least about 2% by weight of solid lubricant; and (d) at least 0.002% by weight of wetting agent, wherein a coefficient of friction is produced which increases with the increased levels of drag between the steel bodies in the sliding and rocking contact, lubricated using this composition.

4. A composition according to claim 3, wherein the composition comprises: (a) 24% -88% by weight of water; (b) 3-15% by weight of the binder; (c) 2-60% by weight of solid lubricant; Y (d) 0.002% by weight of wetting agent.

5. A lubricating composition based on water, comprising: (a) at least 60% by weight of water; (b) at least 5% by weight of the binder; (c) at least 3% by weight of solid lubricant; and (d) at least 3% by weight of friction modifier, wherein the composition has the characteristics of a very high and positive friction, and where a coefficient of friction is produced which increases with the increased levels of drag between the Steel bodies in sliding contact with rolling, lubricated using this composition.

6. A composition according to claim 5, wherein the composition comprises: (a) 60-90% by weight of water; (b) 5-18% by weight of the binder; (c) 3-24% by weight solid lubricant; And (d) 3-32% by weight of friction modifier.

7. A lubricating composition based on water, comprising: (a) at least 60% by weight of water; (b) at least 5% by weight of the binder; (c) at least 3% by weight of solid lubricant, (d) at least 3% by weight of the friction modifier; (e) at least 0.002% wetting agent, where the composition has the characteristics of a very high and positive friction, and where a coefficient of friction is produced which increases with the increased levels of drag between the steel bodies in the sliding contact with rolling, lubricated using this composition.

8. A composition according to claim 7, wherein the composition comprises: (a) 60-90% by weight of water; (b) 5-18% by weight of the binder; (c) 3-24% by weight solid lubricant; (d) 3-32% by weight of friction modifier; and (e) 0.002-2% by weight of wetting agent.

9. A composition based on water, comprising: (a) at least 60% by weight of water; (b) at least 5% by weight of the binder; and (c) at least 3% by weight of friction modifier, wherein the composition has the characteristics of a very high and positive friction, and wherein a coefficient of friction is produced which increases with increased levels of drag between the bodies steel in sliding contact with rolling, lubricated using this composition.

10. A composition according to claim 9, wherein the composition comprises: (a) 60-90% by weight of water; (b) 5-18% by weight of the binder; and: c) 3-32% by weight of friction modifier.

11. A composition based on water, comprising: (a) at least 60% by weight of water; (b) at least 5% by weight of the binder; (c) at least 3% by weight of friction modifier; and (d) at least 0.002% by weight of wetting agent, wherein the composition has the characteristics of a very high and positive friction, and where a coefficient of friction is produced which increases with the increased levels of drag between the bodies steel in sliding contact with rolling, lubricated using this composition.

12. A composition according to claim 11, wherein the composition comprises: (a) 60-90% by weight of water; (b) 5-18% by weight of the binder; (c) 3-32% by weight of friction modifier; and (d) 0.002-2% by weight wetting agent.

13. The composition according to claims 5-12, wherein the coefficient of friction increases to approximately 0.45 in drag levels of up to 2.5%.

14. The composition according to claims 5-12, wherein the coefficient of friction is increased from 0.45 to about 0.72 as the drag increases from about 2.5% to about 30%.

15. The composition according to claims 1-82, wherein the solid lubricant is one or more of molybdenum disulfide or graphite.

16. The composition according to claims 1-8, wherein the solid lubricant is molybdenum disulfide.

17. The composition according to claims 1-12, wherein the lubricant is sodium montmorillonite.

18. The composition according to claims 3, 4, 7, 8, 11 or 12, wherein the wetting agent is nonyl phenoxypolyol.

19. The composition according to claims 5-8, wherein the friction modifier has a particle size in the range of 0.5 to 5 microns.

20. The composition according to claims 5-8, wherein the friction modifier has a particle size in the range of 1 to 2 microns.

21. The composition according to claims 9-12, wherein the friction modifier has a particle size of 10 microns.

22. A lubricating composition, based on water, comprising: (a) 24-80% by weight of water; (b) 3-8% by weight of sodium montmorillonite; (c) 5-60% by weight of molybdenum disulfide; and (d) 0.002-2% by weight of nonyl phenoxypolyol,

23. A lubricating composition, based on water, comprising: (a) 55-88% by weight of water; (b) 5-15% by weight of sodium montmorillonite; (c) 2-18% by weight of molybdenum disulfide; (d) 0.002-2% by weight of nonyl phenoxypolyol,

24. A lubricating composition based on water, comprising: (a) 60-90% by weight of water; (b) 5-18% by weight of sodium montmorillonite; (c) 3-24% by weight of molybdenum disulfide; (d) 3-24 wt% magnesium silicate; and (e) 0.002-2% by weight of nonyl phenoxypolyol, wherein the molybdenum disulfide and the magnesium silicate are present in a ratio of 1: 1 such that the coefficient of friction resulting from the composition varies from about 0.17 to 0.35 according to the levels of drag simply from approximately 2.5% to approximately 30%, between the steel bodies in sliding contact with rolling, lubricated with this composition.

25. A composition based on water, comprising: (a) 60-90% by weight of water; (b) 5-18% by weight of sodium montmorillonite; (c) 3-32% by weight of anhydrous aluminum silicate; and (d) 0.002-2% by weight of nonyl-phenoxypolyol, wherein the resulting coefficient of friction of the composition varies from about 0.45 to 0. 72 according to the drag levels simply from about 2.5% to about 30% between the steel bodies in the sliding sliding contact, using this composition.

26. The composition according to claim 1, for the use of lubrication of steel surfaces.

27. A method for lubricating metal surfaces to reduce friction and wear, using a lubricant composition according to claims 1-25 and 22-25 which comprises depositing a flange of the lubricant composition on the metal surface and allowing the water to evaporate .