ALEXANDRIA, Va., Feb. 24 -- United States Patent no. 12,559,693, issued on Feb. 24, was assigned to IDEMITSU KOSAN Co. LTD. (Chiyoda-ku, Japan).
"Heat treatment oil" was invented by Masashi Nakamura (Yokkaichi, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "A quench oil may be excellent in thermal stability and may be capable of retaining the brightness for a prolonged period of time. Such a quench oil may contain a base oil containing a mineral oil (A), the mineral oil (A) having a 40deg C. kinematic viscosity of 100 to 600 mm2/s and a sulfur content of 0.10 to 0.20% by mass, the base oil having a content of the mineral oil (A) of more than 0.5% by mass, based on the total amount of the base oil."
Th...