Polymer blend for a tire

A polymer blend, consisting of

• (a) 60 to 96 percent by weight of an elastomeric polymer,
• (b) 4 to 35 percent by weight of an aromatic hydrocarbon polymer, and optionally
• (c) 0 to 13 percent by weight of one or more extender oil(s),
• wherein the elastomeric polymer is obtainable by (I) anionic polymerization in the presence of a polymerization initiator in an organic solvent of (I-1) at least one conjugated diene monomer, or (I-2) at least one conjugated diene monomer and at least one of (x) one or more α-olefin monomer(s) or (y) at least one or more of an aromatic vinyl compound or (z) at least one of a vinylsilane compound, and optionally (II) modification of the polymer chain ends obtained in (I) by addition and reaction of at least one compound represented by any of formula (1) to formula (3) and/or formula (11) to formula (15), as defined below;
• wherein the elastomeric polymer (a) has a number average molecular weight (Mn) of 400,000 to 2,000,000 g/mol, and a weight-average molecular weight (Mw) of 500,000 to 3,000,000 g/mol;
• wherein the aromatic hydrocarbon polymer (b) has a number average molecular weight (Mn) of 250 to 1,500 g/mol, and a weight-average molecular weight (Mw) of 350 to 2,500 g/mol, and
• wherein the amounts of the components (a), (b) and (c) are based on the total weight of the polymer blend;
• (R***O)x(R**)ySi-A-S—SiR**3 formula (1),
• wherein each of R** is independently selected from C1-C16 alkyl or alkylaryl;
• R*** is independently selected from C1-C4 alkyl;
• A is selected from C6-C18 aryl, C7-C50 alkylaryl, C1-C50 alkyl and C2-C50 dialkylether;
• and optionally R**, R***, or A may independently be substituted with one or more groups, selected from C1-C4 alkyl, C1-C4 alkoxy, C6-C12 aryl, C7-C16 alkylaryl, di(C1-C7 hydrocarbyl)amino, bis(tri(C1-C12 alkyl)silyl)amino, tris(C1-C7 hydrocarbyl)silyl and C1-C12 thioalkyl;
• x is an integer selected from 1, 2 and 3;
• y is an integer selected from 0, 1 and 2;
• provided that x+y=3;
• ((R1O)x2′(R2)y2′Si—R3—S)s2′M*(R4)t2′(X*)u2′ formula (2),
• wherein M* is silicon or tin;
• x2′ is an integer selected from 1, 2 and 3;
• y2′ is an integer selected from 0, 1, and 2;
• wherein x2′+y2′=3;
• s2′ is an integer selected from 2, 3 and 4;
• t2′ is an integer selected from 0, 1 and 2;
• u2′ is an integer selected from 0, 1 and 2;
• wherein s2′+t2′+u2′=4;
• R1 is independently selected from hydrogen and (C1-C6) alkyl;
• R2 is independently selected from (C1-C16) alkyl, (C7-C16) alkylaryl and (C7-C16) arylalkyl;
• R3 is at least divalent and is independently selected from (C1-C16) alkyl, (C8-C16) alkylarylalkyl, (C7-C16) arylalkyl and (C7-C16) alkylaryl, and each group may be substituted with one or more of the following groups:
• tertiary amine group, silyl group, (C7-C18) aralkyl group and (C6-C18) aryl group;
• R4 is independently selected from (C1-C16) alkyl and (C7-C16) alkylaryl;
• X* is independently selected from chloride, bromide and —OR5*;
• wherein R5* is selected from (C1-C16) alkyl and (C7-C16) arylalkyl;
• (RIO)x1′(RII)y1′Si—RIV—S-E formula (3),
• wherein RI and RII are independently selected from C1-C8 alkyl or C1-C4 alkoxy, provided that at least one of RI and RII are C1-C4 alkoxy;
• x1′ is an integer selected from 1, 2, and 3;
• y1′ is an integer selected from 0, 1 and 2;
• RIV is selected from C1-C8 alkyl;
• and E is RV or of formula (3a):
• wherein RV is C1-C6 alkyl, C6-C12 aryl, C7-C16 alkylaryl, or C7-C16 arylalkyl;
• wherein each R1d is independently selected from (C1-C16) alkyl;
• each R2d is independently selected from (C1-C16) alkyl, (C6-C18) aryl and (C7-C18) alkylaryl;
• R3d is independently selected from divalent (C1-C16) alkyl, divalent (C6-C18) aryl, divalent (C7-C18) aralkyl and —R4d—O—R5d—, wherein R4d and R5d are independently selected from divalent (C1-C6) alkyl;
• and Zd is independently selected from (C1-C16) alkyl, (C6-C18) aryl, (C7-C18) alkylaryl, (C═S)—S—R6d, wherein R6d is selected from (C1-C16) alkyl, (C6-C18) aryl and (C7-C18) alkylaryl, and -M1d(R7d)c4(R8d)d4, wherein M1d is silicon or tin, each R7d is independently selected from (C1-C16) alkyl, (C6-C18) aryl and (C7-C18) alkylaryl;
• each R8d is independently selected from —S—R3d—Si(OR1d)r4(R2d)s4, wherein R1d, R2d and R3d are as defined above, r4 is an integer independently selected from 1, 2 and 3 and s4 is an integer independently selected from 0, 1 and 2, with r4+s4=3;
• c4 is an integer independently selected from 2 and 3;
• d4 is an integer independently selected from 0 and 1;
• and c4+d4=3
• wherein R9e, R10e, R11e and R12e are independently selected from hydrogen, (C1-C16) alkyl, (C6-C16) aryl and (C7-C16) alkylaryl;
• wherein each R13a, R14a, R18a and R19a is independently selected from (C1-C16) alkyl;
• R15a and R20a are independently selected from divalent (C1-C16) alkyl, divalent (C6-C18) aryl, divalent (C7-C18) alkylaryl and —R24a—O—R25a—, wherein R24a and R25a are independently selected from divalent (C1-C6) alkyl;
• R16a and R17a are independently selected from (C1-C16) alkyl and —Si (R26a) (R27a) (R28a), wherein R26a, R27a and R28a are independently selected from (C1-C16) alkyl, (C6-C18) aryl and (C7-C18) alkylaryl;
• each R21a and R22a is independently selected from (C1-C16) alkyl, (C6-C18) aryl and (C7-C18) aralkyl;
• each R23a is independently selected from hydrogen and (C1-C6) alkyl;
• t1 and v are integers independently selected from 1, 2 and 3;
• u1 and w are integers independently selected from 0, 1 and 2;
• t1+u1=3;
• and v+w=3;
• wherein each R29 and R30 is independently selected from (C1-C16) alkyl, (C6-C18) aryl, (C7-C18) alkylaryl and vinyl;
• and x10 is an integer selected from 1 to 6.