Extreme-pressure additive, process for producing the same, cutting fluid, and grinding fluid

摘要

The present invention provides a sulfur-based extreme-pressure additive that is completely soluble in water without using a surfactant, and has satisfactory odor and hue. In addition, the present invention provides a cutting liquid and grinding liquid having superior defoaming property and rust preventive characteristics, while also having high load resistance and lubrication performance comparable to cutting oils and grinding oils of the prior art. The above objects are achieved by an extreme-pressure additive comprising the salt of a condensation product of a sulfurized hydroxy-unsaturated fatty acid, the condensation product having a sulfur content of 8 to 15% by weight (mass), color of 6 or less, and acid value of 80 to 200, and a grinding liquid comprising that extreme-pressure additive and water.