| abstract |
The invention pertains to the synthesis and use of copolymers based on ethylene and/or propylene and vinyl ester(s) which are modified by grafting and are effective for enhancing both the low-temperature resistance and the lubricity of liquid hydrocarbons, more particularly the middle distillates obtained from the distillation of petroleum and crude oils, especially those with a low sulfur content, and relates to a copolymer comprising: a) units derived from ethylene, of formula A -(CH2-CH2)nl- and/or from propylene, of formula A' -((CH3)CH2-CH2)n2-, with n1 + n2 = n ranging from 98 to 643, preferably ranging from 124 to 515; n1 being advantageously equal to n; b) units of formula B: -(CH2-CHOOCR1)m-x- in which R1 represents a linear or branched C1-C15 alkyl group, preferably methyl or propyl, or a C5 to Cl5 branched alkyl group in which the branching is located at any point of the alkyl radical, preferably in position 2 or 3 of the alkyl chain; and preferably selected from the preferred C5-C15 vinyl comonomers, preferably selected from pivalate, isopentanoate, isohexanoate, isononanoate, isodecanoate and/or isotridecanoate, and advantageously 2-ethylhexanoate, neoalkanoates, especially neononanoate, neodecanoate and/or neoundecanoate; with m being from 2 to 105, preferably from 16 to 71, and x being from 0.2 to 105, preferably from 1.6 to 71; c) units of formula C: -(CH2-CHOH)x1- in which x1 is from 0 to 0.30x, preferably xl = 0; d) units of formula D: -(CH2-CHOOCR2)x2- in which x2 is from 0.70x to x, preferably x2 = x, and R2 represents a saturated or unsaturated C8-C24, preferably C14-C20 or else C14 to C18 linear or branched alkyl group, with x = x1 + x2. |