A viscosity index improver, which comprises a polymer (A) having a solubility parameter of 8.6-9.4, a crystallizing initiation temperature of equal to or less than −15° C., and a steric hindrance factor (F) of 0-13, said factor F being defined by the following equation:
F=4X+Y (1) wherein X and Y represent the total numbers of atoms at the 6th position and the 7th position, respectively, in the side chains; said polymer (A) having a Mw of 5,000-2,000,000 and comprising units of at least one monomer selected from the group consisting of:
(a) a monomer represented by the general formula:
CH
2
═C(R
0
)—COO—(AO)
n
—R (2) wherein R
0
is hydrogen atom or methyl group, R is a C
1-40
alkyl group, n is 0 or an integer of 1-20 giving 0-10 on average, A is an alkylene group containing 2-4 carbon atoms, plural A's in case of n being at least 2 are the same or different, and the polyoxyalkylene moiety (AO)
n
in case of the plural A's being different comprises random-wise or block-wise distributed oxyalkylene groups; (b) an alkyl alkenyl ether; (c) an alkenyl carboxylate; and (d) a nitrogen-containing unsaturated monomer.
The suitable monomers, 2-decyl-tetradecyl methacrylate and 2-decyl-tetradecyl acrylate compose the polymer (A), are also described.
一种粘度指数改进剂,它由聚合物 (A) 组成,聚合物 (A) 的溶解度参数为 8.6-9.4,结晶起始温度等于或低于零下 15 摄氏度,立体阻碍因子 (F) 为 0-13,所述因子 F 由下式定义:
F=4X+Y (1) 其中,X 和 Y 分别代表侧链中第 6 位和第 7 位原子的总数;所述聚合物 (A) 的 Mw 为 5,000-2,000,000 并包含至少一种选自以下组别的单体单元:
(a) 由通式表示的单体:
CH
2
═C(R
0
)-COO-(AO)
n
-R(2),其中 R
0
是氢原子或甲基,R 是 C
1-40
烷基,n 为 0 或 1-20 的整数,平均为 0-10,A 为含有 2-4 个碳原子的亚烷基,在 n 至少为 2 的情况下,多个 A 相同或不同,聚氧亚烷基 (AO)
n
在复数 A 不同的情况下包括无规分布或嵌段分布的氧亚烷基;(b) 烷基烯基醚;(c) 烯基
羧酸酯;以及 (d) 含氮不饱和单体。
此外,还介绍了组成聚合物(A)的合适单体--
甲基丙烯酸 2-癸基
十四烷基酯和
丙烯酸 2-癸基
十四烷基酯。