FIELD: chemistry.
SUBSTANCE: invention relates to method of reducing cold flow of polymer composition, versions of polymer composition and to tyre cover. Polymer composition includes the following components: polydiene or polydiene copolymer, solvent, if required, and combination of product of reaction of (i) acetal or alditol ketal and (ii) (a) hydrocarbylated boric acid, (b) aluminium-organic compound, or (c) both hydrocarbylated boric acid and aluminium-organic compound. Aluminium-organic compound is described by formula AlRnX3-n, where each R, which can be similar or different, represents monovalent organic group, which is bound to aluminium atom via carbon atom, where each X, which can be similar or different, represents carbon atom, halogen atom, carboxylate group, alkoxide group or aryloxide group, and where n represents integer number in the range from 1 to 3. In one of the versions polymer composition contains said copolymer and hydrocarbylboric acid ester, which is described by the following formula: 
, where each of R20, R21, R22, R23, R24, R25, R26, R27, R28, R29, R30 and R31 independently represents hydrogen atom or monovalent organic group, and where R20 and R21 and/or R22 and R23 join with formation of bivalent organic group, and where n equals 0, 1 or 2, and R55 represents hydrocarbyl group or ester of hydrocarbylboric acid, which is described by one of the formulas: 
, 
, where each of R20, R21, R22, R23, R24, R25, R26, R27, R28, R29, R30 and R31 independently represents hydrogen atom or monovalent organic group, or where R20 and R21 and/or R22 and R23 join with formation of bivalent organic group, and where n equals 0, 1 or 2, and each of R55 and R56 independently represents hydrocarbyl group. Method of reducing cold flow of polymer composition includes combination of all components mentioned above. Tyre includes tyre component, produced from the claimed composition.
EFFECT: invention makes it possible to improve resistance to cold flow.
12 cl, 4 tbl, 2 ex
