Lubricating oil composition and method for producing same

Abstract

The lubricating oil composition of the present invention is a lubricating oil composition containing a lubricating base oil, a metal-based detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound, wherein the metal-based detergent contains a calcium salicylate and at least one selected from the group consisting of a calcium sulfonate and a magnesium-based detergent; the lubricating oil composition arbitrarily contains an ashless friction modifier; the content of a calcium atom is 0.12 to 0.16 mass % on the basis of the whole amount of the lubricating oil composition; the content of a molybdenum atom is 0.05 to 0.10 mass % on the basis of the whole amount of the lubricating oil composition; and a predetermined coefficient X is less than 0.050.

What is claims is: 
     
         1 . A lubricating oil composition comprising: a lubricating base oil, a metal-based detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound, wherein
 the metal-based detergent contains   a calcium salicylate and   at least one selected from the group consisting of a calcium sulfonate and a magnesium-based detergent,   the lubricating base oil arbitrarily contains an ashless friction modifier,   in the lubricating oil composition, the content of a calcium atom is 0.12 to 0.16 mass % on the basis of the whole amount of the lubricating oil composition;   and the content of a molybdenum atom is 0.05 to 0.10 mass % on the basis of the whole amount of the lubricating oil composition, and   X calculated according to the following expression (1) is less than 0.050:
     X= 3.8×10 −2 −2.7×10 −4   ×[A]− 4.2×10 −1   ×[B]+ 5.4×10 −1   ×[C]− 5.2×10 −3   ×[D]+ 7.3×10 −3   ×[E]   (1)
 
   
       wherein
 [A] denotes a proportion (mass %) occupied by a soap component derived from a calcium sulfonate in the total amount of soap components derived from a calcium salicylate, a calcium sulfonate, and a calcium phenate; 
 [B] denotes the content (mass %) of the magnesium-based detergent as converted into a magnesium atom; 
 [C] denotes the content (mass %) of a boron atom contained in the lubricating oil composition; 
 [D] denotes the content (mass %) of the ashless friction modifier; and 
 [E] denotes E calculated according to the following expression:
     E =([ A]+ 1)×([ B]+ 0.001)  (2)
 
 
 
       the values of [B] to [D] being a value on the basis of the whole amount of the lubricating oil composition. 
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein a total content of the calcium atom and the magnesium atom in the lubricating oil composition is 0.3 mass % or less on the basis of the whole amount of the lubricating oil composition. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the lubricating base oil has a kinematic viscosity at 100° C. of 3 to 5 mm 2 /s and a % Cp by n-d-M ring analysis of 80% or more. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein the boron-containing compound is at least one selected from the group consisting of a borated dispersant, an alkali metal boric acid salt, a borated epoxide, a boric acid ester, a borated aliphatic amine, and a borated amide. 
     
     
         5 . The lubricating oil composition according to  claim 1 , further comprising a non-boron-containing succinimide. 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein the ashless friction modifier is at least one selected from the group consisting of an ester-based ashless friction modifier and an amine-type ashless friction modifier. 
     
     
         7 . The lubricating oil composition according to  claim 1 , further comprising one or more of an additive for lubricating oil selected from the group consisting of a viscosity index improver, a pour-point depressant, an anti-wear agent, an antioxidant, and an antifoaming agent. 
     
     
         8 . The lubricating oil composition according to  claim 1 , which has a kinematic viscosity at 100° C. of less than 12.5 mm 2 /s and a high-temperature high-shear viscosity (HTHS viscosity) at 150° C. of less than 3.5 mPa·s. 
     
     
         9 . The lubricating oil composition according to  claim 1 , which has a base number of 4 to 10 mgKOH/g. 
     
     
         10 . The lubricating oil composition according to  claim 1 , which is used for an internal combustion engine. 
     
     
         11 . A method for producing a lubricating oil composition comprising: blending a lubricating base oil with at least a metal-based detergent, a molybdenum dialkyldithiocarbamate compound, and a boron-containing compound, to obtain a lubricating oil composition, wherein
 the metal-based detergent contains   a calcium salicylate and   at least one selected from the group consisting of a calcium sulfonate and a magnesium-based detergent,   the lubricating base oil is further arbitrarily blended with an ashless friction modifier,   in the lubricating oil composition, the content of a calcium atom is 0.12 to 0.16 mass % on the basis of the whole amount of the lubricating oil composition;   and the content of a molybdenum atom is 0.05 to 0.10 mass % on the basis of the whole amount of the lubricating oil composition, and   X calculated according to the following expression (1) is less than 0.050:
     X= 3.8×10 −2 −2.7×10 −4   ×[A]− 4.2×10 −1   ×[B]+ 5.4×10 −1   ×[C]− 5.2×10 −3   ×[D]+ 7.3×10 −3   ×[E]   (1)
 
   
       wherein
 [A] denotes a proportion (mass %) occupied by a soap component derived from a calcium sulfonate in the total amount of soap components derived from a calcium salicylate, a calcium sulfonate, and a calcium phenate; 
 [B] denotes the content (mass %) of the magnesium-based detergent as converted into a magnesium atom; 
 [C] denotes the content (mass %) of a boron atom contained in the lubricating oil composition; 
 [D] denotes the content (mass %) of the ashless friction modifier; and 
 [E] denotes E calculated according to the following expression:
     E =([ A]+ 1)×([ B]+ 0.001)  (2)
 
 
 
       the values of [B] to [D] being a value on the basis of the whole amount of the lubricating oil composition.