FIELD: chemistry.
SUBSTANCE: present invention relates to the method of producing functionalised, linked or star block copolymer, used in rubber compositions, cross-linked with sulphur and with low hysteresis in the cross-linked state. Described is a method of producing the said copolymer, containing soot and with low hysteresis in the cross-linked state. At least one or the above mentioned blocks consists of a diene elastomer, distinct from polyisoprene, the molar content of branches of one or several conjugate dienes of which exceeds 15%. The method is distinguished by that it involves: (i) copolymerisation of one or several monomers, containing at least one conjugated diene, distinct from isoprene, using a catalyst system, containing a hydrocarbon solvent, halogenation or non-halogenated organo-metal compound A of a group IIIA metal, compound B of an alkali-earth metal and a polymer initiator C, containing C-Li bond, which is formed from non-functionalised mono-lithium containing polyisoprene, meant for forming the said or each polyisoprene block; the said one or several polyisoprene blocks have average molecular mass Mn1 from 2500 to 20000 g/mol, in effect that, one or several blocks, containing diene elastomer, distinct from polyisoprene, contains 70% or more 1,4-trans-branches and has average molecular mass Mn2 from 65000 to 350000 g/mol, and (ii) addition into the copolymerisation product of a functionalised, linking or star structure forming agent, containing one, two or at least three epoxy groups, respectively, for functionalising, linking or forming a star structure of the given block, consisting of diene elastomer, distinct from polyisoprene. Description is also given a functionalised, linked or star block-copolymer, cross-linkable or cross-linked rubber composition, containing the said functionalised, linked or star block-copolymer, and description is also given of a pneumatic tyre tread and a pneumatic tyre.
EFFECT: obtaining a block-copolymer, which is used in compositions for pneumatic tyre treads, and which reduces hysteresis of the given composition in cross-linked state.
40 cl, 4 ex
