Lubricating Greases Containing Lignosulfonate, The Production Thereof, and the Uses Thereof

Abstract

The object of the invention are lubricating greases that contain calcium lignin sulfonates, and which consist of a base oil, calcium soaps, calcium lignin sulfonate having average molecular weights (weight average) greater than 10,000 g / mol as well as other, optional alkaline earth lignin sulfonates, producible by heating to temperatures above 120° C. converting and driving out components with low boiling point in order to produce a base grease, and cooling and addition of base oil and possibly other additives with mixing, a corresponding process, and use of the lubricating greases containing calcium lignin sulfonate.

Description

[0001]The invention relates to a process for producing lubricating greases that contain calcium lignin sulfonate, lubricating greases of such kind, and use thereof.[0002]Lignin is a complex polymer based on phenylpropane units, which are cross-linked to each other with a wide variety of different chemical bonds. Lignin is present in plant cells together with cellulose and hemicellulose. Lignin itself is a cross-linked macromolecule with average molecular weights of for example at least 10,000 g / mol (weight average).[0003]There are essentially 3 types of monolignol monomers that can be identified as monomer components of lignin, and they differ in the degree of their methoxylation. They are p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. These lignols are incorporated in the lignin structure in the form of hydroxyphenyl (H)-, guaiacyl (G)- and syringal (S) units. Naked-seeded plants (gymnosperms) such as pine trees contain mostly G units and low proportions of H units. All...

AI Technical Summary

Benefits of technology

[0003]There are essentially 3 types of monolignol monomers that can be identified as monomer components of lignin, and they differ in the degree of their methoxylation. They are p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. These lignols are incorporated in the lignin structure in the form of hydroxyphenyl (H)-, guaiacyl (G)- and syringal (S) units. Naked-seeded plants (gymnosperms) such as pine trees contain mostly G units and low proportions of H units. All lignins contain small amounts of incomplete or modified monolignols. The primary function of lignins in plants is to lend them mechanical stability by cross-linking the vegetable polysaccharides. Lignin constitutes about ⅓ of the dry mass of wood, and according to rough estimates 30% of the non-fossil organic carbon mass on Earth. It is the third most abundant organic material after cellulose and chitin, and is thus a very readily available, renewable raw material for industrial products.

[0072]A special aspect of the present invention is that it may be used to obtain cost-optimised lubricating grease formulations for lubricating points that are under heavy load, such as in constant velocity joints in particular, and that are well compatible with bellows containing, for example, thermoplastic polyether esters (TPE) and chloroprenes (CR), while offering a high degree of efficiency, low wear and a long service life.

Problems solved by technology

In modern lubricating grease formulations, a not inconsiderable proportion of the formulation cost is devoted to tribochemically acting extreme pressure and anti-wear additives (EP / AW additive), with the result that they often become the price drivers for lubricating greases.

Many of these additives are produced in complicated, multistage synthesis processes, and their use is limited both in terms of the nature of the application and of their effective concentration in the final formulation due to the toxicological side effects that occur in many cases.

In some applications, for example in constant velocity joint shafts or in slow running and heavily loaded rolling bearings, deficient lubrication conditions and / or contact between friction partners is unavoidable even when liquid additives are introduced.

But these components are also often expensive and can have a critical effect on the overall cost of a lubricant formulation.

Usual lubricant additives and solid lubricants are normally based on non-renewable raw materials and are often poorly biodegradable.

Furthermore, most common anti-wear additives and friction reducing lubricant additives entail expensive chemical synthesis processes, which represent a significant cost factor.

Particularly when solid lubricants are used for heavily loaded friction points, materials most frequently used are relatively expensive, for example MoS2 or PTFE.