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.

Abstract: For efficiently producing a dialkyl polysulfide which is able to be favorably used as an extreme-pressure additive which does not easily corrode the metal surface, and an extreme-pressure additive and lubricating fluid composition including the dialkyl polysulfide, provided is a method for producing dialkyl polysulfide including a first step of reacting an olefin compound (a) represented by General Formula (1): R1R2C?CHR3 (where R1 and R2 each are an alkyl group, R3 is a hydrogen atom or an alkyl group, and the total number of carbon atoms of R1, R2 and R3 is 2 to 20) with sulfur in the presence of a hydrogen sulfide to thereby obtain crude dialkyl polysulfide (A), and a second step of reacting the crude dialkyl polysulfide (A) and a sulfide of an alkali metal in a solvent including an alcohol to thereby reduce the number of sulfur atoms in the crude dialkyl polysulfide (A).

Abstract: The present invention provides a dialkyl polysulfide which can be suitably used as an extreme pressure additive that can be added to a lubricant in a wide range of amounts, that enables effective formation of a film of a metal sulfide on a metal surface, and that is less likely to cause corrosion of the metal surface. In particular, provided is a dialkyl polysulfide containing compounds represented by General Formula (1) (where R1 and R2 each represent an alkyl group, and n is an integer from 1 to 6), wherein the total content of a compound in which n in General Formula (1) is 2 and a compound in which n in General Formula (1) is 3 is in the range of 80 to 100 mass % relative to the entire amount of the compounds represented by General Formula (1).

Abstract: For efficiently producing a dialkyl polysulfide which is able to be favorably used as an extreme-pressure additive which does not easily corrode the metal surface, and an extreme-pressure additive and lubricating fluid composition including the dialkyl polysulfide, provided is a method for producing dialkyl polysulfide including a first step of reacting an olefin compound (a) represented by General Formula (1): R1R2C?CHR3 (where R1 and R2 each are an alkyl group, R3 is a hydrogen atom or an alkyl group, and the total number of carbon atoms of R1, R2 and R3 is 2 to 20) with sulfur in the presence of a hydrogen sulfide to thereby obtain crude dialkyl polysulfide (A), and a second step of reacting the crude dialkyl polysulfide (A) and a sulfide of an alkali metal in a solvent including an alcohol to thereby reduce the number of sulfur atoms in the crude dialkyl polysulfide (A).

Abstract: The present invention provides a dialkyl polysulfide which can be suitably used as an extreme pressure additive that can be added to a lubricant in a wide range of amounts, that enables effective formation of a film of a metal sulfide on a metal surface, and that is less likely to cause corrosion of the metal surface. In particular, provided is a dialkyl polysulfide containing compounds represented by General Formula (1) (where R1 and R2 each represent an alkyl group, and n is an integer from 1 to 6), wherein the total content of a compound in which n in General Formula (1) is 2 and a compound in which n in General Formula (1) is 3 is in the range of 80 to 100 mass % relative to the entire amount of the compounds represented by General Formula (1).