Process for the synthesis of greases permitting a good control o

Details Process for the synthesis of greases permitting a good control o Process for the synthesis of greases permitting a good control o

1989-11-29

1992-07-28

Willis, Jr., Prince

Compositions

Electrolytes for electrical devices

252 35, 252 38, 252 39, 252 41, C10M14100

Patent

active

051338874

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

(1) Field of the Invention
This invention relates to a process for the synthesis of greases permitting a good control of their mechanical behaviour.
(2) Description of the Related Art
Greases are colloidal systems made up of a three- o dimensional network of thickening molecules in an oil.
The thickeners employed to form this network may be, for example, metal soaps, by themselves or mixed with polymers.
The oil belongs to the class of lubricating oils. This oil is trapped and kept within the three-dimensional network of the thickener by a combination of capilliary, adsorption and steric interaction forces.
Greases are widely employed for lubricating rotating mechanical components, in fields as diverse as domestic appliances, motor vehicles or aviation. They have the advantage of a great ease of application and of a reduced maintenance.
The properties of greases can be improved by the use of additives. It is thus possible to improve the resistance to oxidation, to wear and to corrosion by the addition of amine salts, of metal sulphates, of naphthenates, of esters and of nonionic surfactants to the greases.
The extreme-pressure properties can be improved by the addition of graphite, molybdenum disulphide, zinc oxide or talc.
It is also known to modify the mechanical properties of greases by varying the proportion of metal soap and the heat treatment during their process of manufacture.
The conditions of use of greases frequently call for contradictory properties. Thus, for a given consistency and mechanical working strength it is sometimes advantageous to have increased adhesion and/or fluidity properties. Currently known means do not allow this problem to be solved.
We have now found a process which, on the one hand, permits a good control of the mechanical behaviour of greases and, on the other hand, makes it possible to modify the contradictory mechanical properties in a continuous way.


SUMMARY OF THE INVENTION

This process for the synthesis of greases consists in the addition of at least one cosurfactant to the mixture of the thickener in the oil, characterized in that the addition of the said cosurfactant is carried out already at the initial stage of the formation of the three-dimensional filamentary network of the grease.


DETAILED DESCRIPTION OF THE INVENTION

This three-dimensional network is formed when the temperature of the mixture of thickener, oil and cosurfactant is between the waxy transition and melting temperatures of the thickener.
The waxy transition temperature is defined as being the first stage of structural disorganization which the crystalline solid undergoes when the temperature is increased (M. J. Vold et al., J. Colloid Sci., 5, 1(1950) and R. M. Suggitt NLGI Meeting XXIV, 9, 367 (1960)).
When the cosurfactant is introduced at the initial stage of the formation of the three-dimensional network of the thickener, the cosurfactant and the thickener are in structural competition. The incorporation of the cosurfactant into the network allows the mechanical behaviour of the grease to be controlled.
The oil employed for the manufacture of greases is a lubricating oil of natural origin, such as paraffinic and naphthenic oils or else a synthetic oil. Diesters, alpha-olefin polymers and silicone oils may be mentioned among the synthetic oils.
The thickeners which form part of the composition of greases are in most cases metal soaps. Fatty acids are preferably employed, in the form of a lithium, sodium, calcium, barium or aluminium salt. Lithium salts are the most commonly employed, and more particularly the lithium salt of 12-hydroxystearic acid.
In this case, for example, the waxy transition temperature is 163.degree. C., while the melting temperature is 215.degree. C.
The cosurfactant may be chosen from alcohols, amines, carboxylic and sulphonic acids and their alkali metal and alkaline-earth metal salts.
The alcohols, amines and carboxylic acids are generally employed in a free form, while sulphonic acids are employed in the form of alkali metal sulphate

REFERENCES:
patent: 2456642 (1948-12-01), Merker
patent: 2892777 (1959-06-01), Morway
patent: 3158574 (1964-11-01), Greenwood et al.
patent: 3242079 (1966-03-01), McMillen

Affiliated with

Also associated with

Rating

Process for the synthesis of greases permitting a good control o does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the synthesis of greases permitting a good control o, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the synthesis of greases permitting a good control o will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1685568