| 摘要 |
<p>An engine oil contains a lubricating oil and an overbased calcium sulfonate having a dispersion of calcite-core micelles, which engine oil has commercial haze free properties, namely a Hazitron test value of less than about 30 and more particularly less than about 15 to 10, and commercial anti-wear properties, namely exhibiting a 4-Ball wear test scar diameter of less than 0.4 mm. The detergent has a TBN of from 100 to 400 and yet a viscosity of no more than 100,000 cps at 25 °C and usually 20,000 to 30,000 cps at 25 °C. The overbased calcium sulfonate detergent provides a stable dispersion of calcite-core sulfonate micelles in the oil. The calcite overbased sulfonate is substantially free of amorphous, vaterite and aragonite forms of the calcium carbonate. The method of producing the improved calcite-core dispersion overbased calcium sulfonate provides for reacting an overbased amorphous calcium sulfonate having a TBN of about 400 or more with a C1 to C6 carboxylic acid or salt, such as acetic acid or calcium acetate, a C1 to C5 alkanol such as, methanol, and water, in a hydrocarbon solvent or oil, at closely controlled temperatures up to and to commensurate with the boiling point of the hydrocarbon solvent for usually about up to 1 1/2 hours to convert the amorphous calcium carbonate to a stable dispersion of a calcite-core micellar structure.</p> |
