To provide a conjugated diene graft polymer having high transparency, heat resistance and weather resistance, and a method for producing the conjugated diene graft polymer. A method for producing a conjugated diene graft polymer in which a side chain (b) including a polymer including at least one monomer unit selected from the group consisting of a conjugated diene unit and an aromatic vinyl compound unit is bonded to a main chain (a) including a polymer including a conjugated diene unit, via a hetero atom Z serving as a branching point and having a valence of not less than 3, the method including a step of reacting a specific active end polymer and a specific functional group-modified conjugated diene polymer having a functional group in a side chain to thereby produce a conjugated diene graft polymer; and a step of recovering the conjugated diene graft polymer obtained.

To provide a conjugated diene graft polymer having high transparency, heat resistance and weather resistance, and a method for producing the conjugated diene graft polymer. A method for producing a conjugated diene graft polymer in which a side chain (b) including a polymer including at least one monomer unit selected from the group consisting of a conjugated diene unit and an aromatic vinyl compound unit is bonded to a main chain (a) including a polymer including a conjugated diene unit, via a hetero atom Z serving as a branching point and having a valence of not less than 3, the method including a step of reacting a specific active end polymer and a specific functional group-modified conjugated diene polymer having a functional group in a side chain to thereby produce a conjugated diene graft polymer; and a step of recovering the conjugated diene graft polymer obtained.

The method for producing a conjugated diene-based polymer of the invention comprises step 1 in which a polymerization initiator is added to a monomer including a conjugated diene compound in a hydrocarbon solvent to obtain a polymerization solution, and step 2 in which a polymerization initiator is further added to the polymerization solution either once or two or more times to obtain a polymer with an active end, wherein in step 1 and/or step 2, a modifying agent is added which has a functional group that is copolymerizable with the conjugated diene compound.

A carboxyl group-containing nitrile rubber comprising an α,β-ethylenically unsaturated nitrile monomer unit in a content of 5 to 60 wt % and having an iodine value of 120 or less, wherein the carboxyl group-containing nitrile rubber has a polymer Mooney viscosity (ML1+4, 100° C.) of 60 or less and a polymer pH of 7 or less.

A carboxyl group-containing nitrile rubber comprising an α,β-ethylenically unsaturated nitrile monomer unit in a content of 5 to 60 wt % and having an iodine value of 120 or less, wherein the carboxyl group-containing nitrile rubber has a polymer Mooney viscosity (ML1+4, 100° C.) of 60 or less and a polymer pH of 7 or less.

The present disclosure provides ethanol comprising an inorganic component and/or an organic component. The inorganic component may contain at least one component selected from the group consisting of: silicon having a content of 10 mg/L or more and 100 mg/L or less; chromium having a content of 0.6 mg/L or less; iron having a content of 2.0 mg/L or less; sodium having a content of 150 mg/L or more and 1000 mg/L or less; and potassium having a content of 1.0 mg/L or more and 10 mg/L or less. The organic component may contain at least one component selected from the group consisting of: aliphatic hydrocarbon having a content of 0.16 mg/L or more and 10 mg/L or less; aromatic hydrocarbon having a content of 0.4 mg/L or more and 10 mg/L or less; and dialkyl ether having a content of 0.1 mg/L or more and 100 mg/L or less.

Branched block copolymers, derived from alkenyl aromatic hydrocarbon-1,3-diene monomer system, and branched polyisoprene homopolymers, derived from isoprene, are obtained by polymerization in the presence of an anionic initiator; at a temperature from 0° C. to 100° C.; followed by coupling with a multifunctional coupling agent of formula (R.sup.1O).sub.3Si—Y—Si(OR.sup.2).sub.3, wherein R.sub.1 and R.sub.2 are independently C.sub.1-C.sub.6 alkyl groups; and Y is a C.sub.2-C.sub.8 alkylene group. The polymers thus obtained can be used in many applications, including rubber cements having high solids content and low zero shear viscosities, and for producing aqueous latices therefrom.

The present disclosure relates to a rubber composition for tire tread and a tire manufactured by using the same, and the rubber composition for tire tread improves rolling resistance and abrasion resistant performance and can improve handling and braking performances on a wet road surface and an ice and snow road surface at the same time by comprising 100 parts by weight of raw rubber and 70 to 120 parts by weight of a reinforcing filler, wherein the raw rubber includes 0 to 50 parts by weight of natural rubber, 20 to 100 parts by weight of a melt grafting-functionalized styrene butadiene rubber, and 0 to 30 parts by weight of butadiene rubber.

A functionalized elastomer comprising the reaction product of a living elastomeric polymer and a polymerization terminator of formula I

[R.sup.1].sub.n—B—[X—R.sup.2].sub.m  I

where B is boron; X is oxygen or nitrogen; R.sup.1 is independently vinyl, oxiranyl, phenyl, 1-alkenyl of 2 to 8 carbon atoms, alkyl of 1 to 8 carbon atoms including at least one halogen atom, 1-alkenyl of 2 to 8 carbon atoms including at least one halogen or one hydrogen; R.sup.2 is independently C1 to C8 alkyl, C8 to C14 aryl; or when m>1 R.sup.2 may be taken together to form a substituted or unsubstituted cyclic structure comprising 2 to 16 carbon atoms where the cyclic structure may be heterocyclic or non-heterocyclic; n is 1 or 2, m is 1 or 2, and n+m=3.

A polyhydroxyl-containing polymer has good biocompatibility, strong binding performance with substances the same surface of which contains oxygen, nitrogen, and so on and that easily form hydrogen bonds. A solution formed by the polymer adheres poorly to an intubation microcatheter, but adheres strongly to blood vessels, skin, and glass, and may be used as a vascular embolization agent.