ES2561821T3 - Lubricating greases containing lignin sulphonate, its manufacture and use - Google Patents

Abstract

Process for manufacturing lubricating greases containing lignin sulphonate, which comprises a) the step of bringing into contact: - at least one base oil - at least one calcium soap of a saturated or unsaturated monocarboxylic acid with 10 to 32 atoms carbon, if substituted, - at least one complexing agent selected from: (i) an alkaline salt, except sodium salt, an alkaline earth salt or aluminum salt, a saturated or unsaturated monocarboxylic acid or hydroxycarboxylic acids with 2 to 8, a dicarboxylic acid with 2 to 16 carbon atoms, optionally substituted, (ii) an alkaline salt and / or alkaline earth salt of boric acid and / or phosphoric acid, including its reaction products with LiOH and / or Ca (OH) 2, and (iii) their mixtures and - at least one calcium lignosulfonate with average molecular weights such as average weight greater than 10,000 g / mol, heating at more than 120 ° C for the reaction and expulsion of boiling point components Low to make a base grease and b) the cooling step by adding base oil and possibly additives by mixing.

Description

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According to the state of the art, for the manufacture of soaps fats with high drip points in many cases, especially treated and expensive fatty acids, such as 12-hydroxystearic acid, or special complexing agents such as borates or acetic acid salts, must be used sebacic acid and azelaic acid, which have only a simultaneous reduced effect as a wear protection additive and friction reducer. Through the use of calcium lignosulfonates, the use of the aforementioned components can be reduced or even dispensed with. The use of calcium lignosulfonates also offers the possibility of formulating high-performance lubricant greases based on renewable raw materials, regardless of chemical additives that are harmful to the environment.

If oils composed of esters of unmodified or slightly modified native fatty acids are thickened with metal soaps based on animal or vegetable fatty acids and lignin sulfonates are used as the sole thickener and at the same time as an additive component, then lubricating greases are obtained which were produced exclusively based on renewable raw materials, with the exception of calcium hydroxide used for metallic soaps. These greases have an effect against aging and wear, as well as increase load resistance and reduce friction through the use of lignin sulphonates as thickener components.

The lubricating greases according to the invention are particularly suitable for use in or for constant speed articulated shafts, bearings and gears.

If the base oils used consist of readily biodegradable esters, such as those containing mostly renewable raw materials, lubricating greases are also suitable for total loss lubrication in environmentally sensitive areas (for example in mining or agriculture).

In the special case of maintenance-free constant speed articulated axle lubrication, the lubricating grease was first formulated with calcium lignosulfonate, which, unlike the state of the art completely without MoS2 and other organic and inorganic molybdenum compounds, leads to high lifespan and good effectiveness.

In addition, the absence of other additives such as friction coefficient reducers, against load and wear, causes good compatibility with usual materials for articulated tree bellows, such as chloroprene rubber and thermoplastic polyether esters. Since the sulfur contained in lignin sulfonate is linked through thermally stable sulfonate groups, unlike sulfur bonded in conventional additives, which is only released at very high temperatures and / or with very high activation energies, it can present in lubricating grease applications only in the case of tribocontacts under very high loads. In this way, vulcanization or subsequent crosslinking of rubber materials by sulfur released from the aged lubricant is largely prevented.

Through the use of calcium lignosulfonate in a superbasic regulated lubricating grease formulation through excess calcium hydroxide, free lignosulfonic acid is prevented from developing a hydrolytic effect on bellows materials, such as thermoplastic polyether esters.

A particular aspect of the present invention is to achieve optimized lubricating grease formulations in terms of costs for lubrication points with high load, in particular in constant speed joints, which have good compatibility with respect to bellows, structured by example based on thermoplastic polyether esters (TPE) and chloroprene (CR), while offering a high degree of effectiveness, reduced wear and a long service life.

Manufacturing examples

Example A (comparative example):

In a reactor, in 12000 g of a base oil mixture, 958 g of stearic fatty acid, 958 g of beef tallow, 958 g of calcium acetate, 27.7 g of trisodium phosphate, 27.7 g of calcium borate and 358 g of calcium hydroxide, and 150ml of water were added. The load was heated by stirring in a set temperature program to reach 198 ° C and the water added and the reaction water evaporated. In the cooling phase additives were added to the load at certain temperatures (see table).

After regulation of the load to the desired consistency through the addition of 3700 g of base oil mixture, the final product was homogenized by a toothed colloid mill. The grease thus obtained is suitable for example as grease for articulated trees of constant speed.

Example B:

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Claims (1)

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