Abstract: In metalworking, the amount of sulfur supplied is stabilized in wide temperature and pressure ranges and under an external force, such as a shear force. Thus, a stable iron sulfide film can be formed on the metal surface, and lubricity can be maintained for extended periods. Furthermore, a bulky sulfurized fat or oil with a high molecular weight can be used to form a rigid lubricating oil film with a large oil film thickness on the metal surface and thereby prevent metals from approaching each other. A sulfur-based extreme-pressure agent containing a polysulfide (a) and a sulfurized fat or oil (b) at a mass ratio in the range of 1:0.1 to 1:10. A metalworking fluid containing the sulfur-based lubricating oil composition is also related to.

Abstract: A lubricating oil composition with high thermal stability, corrosion resistance, and extreme-pressure performance is provided. The present invention have been completed by finding that a lubricating oil composition containing a particular primary aliphatic polysulfide has excellent thermal stability and extreme-pressure performance. A lubricating oil composition containing a base oil and an additive agent, wherein an aliphatic polysulfide constitutes as an additive agent 1% to 10% by mass of the lubricating oil composition, and a primary aliphatic polysulfide constitutes 1% to 50% by mass of the aliphatic polysulfide.

Abstract: In metalworking, the amount of sulfur supplied is stabilized in wide temperature and pressure ranges and under an external force, such as a shear force. Thus, a stable iron sulfide film can be formed on the metal surface, and lubricity can be maintained for extended periods. Furthermore, a bulky sulfurized fat or oil with a high molecular weight can be used to form a rigid lubricating oil film with a large oil film thickness on the metal surface and thereby prevent metals from approaching each other. A sulfur-based extreme-pressure agent containing a polysulfide (a) and a sulfurized fat or oil (b) at a mass ratio in the range of 1:0.1 to 1:10. A metalworking fluid containing the sulfur-based lubricating oil composition is also related to.

Abstract: A lubricating oil composition with high thermal stability, corrosion resistance, and extreme-pressure performance is provided. The present invention have been completed by finding that a lubricating oil composition containing a particular primary aliphatic polysulfide has excellent thermal stability and extreme-pressure performance. A lubricating oil composition containing a base oil and an additive agent, wherein an aliphatic polysulfide constitutes as an additive agent 1% to 10% by mass of the lubricating oil composition, and a primary aliphatic polysulfide constitutes 1% to 50% by mass of the aliphatic polysulfide.