Patent ID: 8568609

Claim:
A lubricating oil composition for a refrigerator, comprising: a base oil; and an additive added to the base oil, wherein the base oil is at least one compound selected from the group consisting of alkyl naphthalene, polycarbonate, an ether-base compound represented by formula (1) and a polyalkylene glycol represented by formula (3), Ra—[(ORb)n-(B)—(ORc)k]x-Rd (1) where: Ra and Rd each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms or a hydrocarbon group having 2 to 6 bonding sites and 1 to 10 carbon atoms; Rb and Rc each represent an alkylene group having 2 to 4 carbon atoms; n and k each represent an integer in a range of 0 to 20; x represents an integer in a range of 1 to 6; and (B) represents a polymerization site comprising 3 or more monomer units each represented by formula (2) where: R 4 , R 5 and R 6 each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, R 4 , R 5 and R 6 being mutually the same or different; R 7 represents a divalent hydrocarbon group having 1 to 10 carbon atoms or divalent ether-bonded oxygen-containing hydrocarbon group having 2 to 20 carbon atoms; R 8 represents a hydrogen atom, or a hydrocarbon group having 1 to 20 carbon atoms; m represents a number whose average value is in a range of 0 to 10; when m is plural, plural m are mutually the same or different per each unit; R 4 to R 8 each are mutually the same or different per each unit; when R 7 O is plural, plural R 7 O are mutually the same or different; and when both k and n in the formula (1) are 0, m is an integer of 1 or larger in the formula (2), R 9 —[(OR 10 ) m1 —OR 11 ] n1 (3) where: R 9 represents an alkyl group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms or an aliphatic hydrocarbon group having 2 to 6 bonding sites and 1 to 10 carbon atoms, R l0 represents an alkylene group having 2 to 4 carbon atoms, R 11 represents an alkyl group having 1 to 10 carbon atoms or an acyl group having 2 to 10 carbon atoms, n1 represents an integer in a range of 1 to 6, and m1 represents a number that is determined such that the average value of m1 multiplied by n1 is in a range of 6 to 80, and the additive is selected from the group consisting of 1-tetradecene, 1-hexadecene, and 1-octadecene.