A vapor film-rupturing agent is provided that is prepared from asphalt as a staring material, so as to have a fraction (x) (% by mass) of a saturated component and a fraction (y) (% by mass) of an asphaltene component based on the total fraction 100% by mass of the saturated component, the asphaltene component, an aromatic component, and a resin component obtained by any one of analysis methods described in the Japan Petroleum Institute Standard and Manuals Testing Method for Petroleum Products JPI-5S-70-10 and the British Standard Test Method IP-469 that satisfy one or more of the following conditions (1) to (3): condition (1): 1.2926×(x)/100−8.113×(y)/100+2.3384≦2.400, condition (2): (y) ≧7.0, and condition (3): ((y)/(x)) ≧0.5. The vapor film-rupturing agent is capable of preparing a thermal treatment oil composition having a high vapor film-rupturing effect with a characteristic number of seconds in the cooling capability test according to JIS K2242 (2012) of 2.50 seconds or less.

A vapor film-rupturing agent is provided that is prepared from asphalt as a staring material, so as to have a fraction (x) (% by mass) of a saturated component and a fraction (y) (% by mass) of an asphaltene component based on the total fraction 100% by mass of the saturated component, the asphaltene component, an aromatic component, and a resin component obtained by any one of analysis methods described in the Japan Petroleum Institute Standard and Manuals Testing Method for Petroleum Products JPI-5S-70-10 and the British Standard Test Method IP-469 that satisfy one or more of the following conditions (1) to (3): condition (1): 1.2926×(x)/100−8.113×(y)/100+2.3384≤2.400, condition (2): (y)≥7.0, and condition (3): ((y)/(x))≥0.5. The vapor film-rupturing agent is capable of preparing a thermal treatment oil composition having a high vapor film-rupturing effect with a characteristic number of seconds in the cooling capability test according to JIS K2242 (2012) of 2.50 seconds or less.

A vapor film-rupturing agent is provided that is prepared from asphalt as a staring material, so as to have a fraction (x) (% by mass) of a saturated component and a fraction (y) (% by mass) of an asphaltene component based on the total fraction 100% by mass of the saturated component, the asphaltene component, an aromatic component, and a resin component obtained by any one of analysis methods described in the Japan Petroleum Institute Standard and Manuals Testing Method for Petroleum Products JPI-5S-70-10 and the British Standard Test Method IP-469 that satisfy one or more of the following conditions (1) to (3): condition (1): 1.2926×(x)/100−8.113×(y)/100+2.3384≤2.400, condition (2): (y)≥7.0, and condition (3): ((y)/(x))≥0.5. The vapor film-rupturing agent is capable of preparing a thermal treatment oil composition having a high vapor film-rupturing effect with a characteristic number of seconds in the cooling capability test according to JIS K2242 (2012) of 2.50 seconds or less.

A heat treatment oil composition is provided that suppresses the decrease of luster in a heat treatment of a metal material, and is capable of suppressing the increase of the number of second (characteristic number of second) until reaching the temperature where the vapor blanket stage ends with the lapse of time and the decrease of the kinetic viscosity with the lapse of time. The heat treatment oil composition contains (A) a base oil and (B) a vapor blanket breaking agent selected from one or more of a petroleum resin, a terpene resin, rosin, and derivatives thereof.

A heat treatment oil composition is provided that suppresses the decrease of luster in a heat treatment of a metal material, and is capable of suppressing the increase of the number of second (characteristic number of second) until reaching the temperature where the vapor blanket stage ends with the lapse of time and the decrease of the kinetic viscosity with the lapse of time. The heat treatment oil composition contains (A) a base oil and (B) a vapor blanket breaking agent selected from one or more of a petroleum resin, a terpene resin, rosin, and derivatives thereof.

A lubricant composition improves a performance of reducing a formation of compressor deposit. The lubricant composition also ensures low temperature properties of the lubricant composition. The lubricant composition includes 14 mass % or more of a fraction having a boiling point of 500 C. to 550 C. and 5 mass % or more of a fraction having a boiling point of over 550 C.

A lubricating oil for press working contains a base oil and a fat or oil-containing additive and a calcium-containing additive added to the base oil. The proportion of the fat or oil-containing additive with respect to the whole volume of the lubricating oil for press working is 10 to 30%. The proportion of the calcium-containing additive with respect to the whole volume of the lubricating oil for press working is 5 to 15%.

A lubricating oil for press working contains a base oil and a fat or oil-containing additive and a calcium-containing additive added to the base oil. The proportion of the fat or oil-containing additive with respect to the whole volume of the lubricating oil for press working is 10 to 30%. The proportion of the calcium-containing additive with respect to the whole volume of the lubricating oil for press working is 5 to 15%.

A heat treatment oil composition is provided that suppresses the decrease of luster in a heat treatment of a metal material, and is capable of suppressing the increase of the number of second (characteristic number of second) until reaching the temperature where the vapor blanket stage ends with the lapse of time and the decrease of the kinetic viscosity with the lapse of time. The heat treatment oil composition contains (A) a base oil and (B) a vapor blanket breaking agent selected from one or more of a petroleum resin, a terpene resin, rosin, and derivatives thereof.

A heat treatment oil composition is provided that suppresses the decrease of luster in a heat treatment of a metal material, and is capable of suppressing the increase of the number of second (characteristic number of second) until reaching the temperature where the vapor blanket stage ends with the lapse of time and the decrease of the kinetic viscosity with the lapse of time. The heat treatment oil composition contains (A) a base oil and (B) a vapor blanket breaking agent selected from one or more of a petroleum resin, a terpene resin, rosin, and derivatives thereof.