Patent GB-977366-A (GB)
Title: A process for the preparation of a water resistance concentrated clay suspension
IPC: C04B33/04
Filed: 1963-01-21
Abstract: A clay suspension suitable for preparing a clay grease is obtained by dispersing a clay mineral in water, physically separating the gangue, heating the degangued clay hydrosol with an acid to cause reaction with the clay-contaminating calcite, and adding to the degangued and acid-treated clay hydrosol a waterproofing coating compound.  After removal of the water phase, the clay may be further dehydrated to form a pulverulent solid or may be mixed with a lubricating oil, dehydrated and formed into a grease.  A suitable clay, e.g. montmorillonite, nontronite, illite, Wyoming Bentonite or hectorite is dispersed in water, and the resultant gangue is removed, e.g. by fractionation, cyclone separation or high-speed centrifugation to give a dilute, preferably 2-4%, clay hydrosol.  Alkali metal cations are then removed from the clay by the addition of phosphoric acid (e.g. 1-10% by weight, based on clay) at 10-50 DEG C.  Calcite is removed by the addition of HCl, H3PO4 or CH3COOH, or a mixture thereof at, for example, 80-100 DEG  C., using 50-70% acid based on dry weight of clay or 3-7.5% acid if 1-10% of a surfactant is included.  It is preferred that the surfactant be hydrophobic cationic and identical with the water-proofing coating compound. Preferred surfactants are amino amides formed from polyethylene polyamines and a saturated fatty acid, e.g. capric, undecyclic, lauric, tridecylic or myristic.  A water washing step is included before or after the addition of the water proofing coating compound. The separated water phase may be removed before or after the coating compound is added.  The coating compound is added in an amount 60-110% by weight of the dry clay, and is preferably followed by the addition of a chlorinated wax (40-120% by weight of dry clay) containing 20-60%, preferably 30-45%, of chlorine by weight.  The resultant concentrated acid-treated clay hydrosol may be dehydrated to form a powdery solid and stored as such, or may be mixed with a lubricating oil, i.e. a mineral oil or a synthetic oil (e.g. aliphatic polyesters, aromatic polyethers or mixtures thereof), further dehydrated and sheared to form a grease.ALSO:A grease containing an oleophilic clay in a lubricating oil base is obtained from a concentrated water-resistant clay suspension by mixing it with the oil, dehydrating the mixture and subjecting it to shear. The clay suspension is prepared by dispersing a clay mineral in water, physically separating the gangue, heating the hydrosol with acid to react with the calcite contaminant, and finally adding a water-proofing coating compound to separate a proportion of the water. The waterproofing coating compound is a surfactant, preferably an amino amide formed from a polyethylene polyamine and a saturated fatty acid; a chlorinated hydrocarbon wax may be employed in conjunction with the surfactant.  Lubricating oils useful in the preparation of the greases include mineral oils and water-immiscible synthetic lubricants, such as aliphatic polyesters e.g. bis (2-ethylhexyl) sebacate or aromatic polyethers (polyphenyl ethers) and mixtures thereof.