Kuraray Co., Ltd.

Yoshikazu Ueno

Daisuke Koda

Yosuke Uehara

Hiroshi Kanbara

Satoshi Motoda

Atsushi Inatomi

Junya Takai

Masahiro Kashioka

Zhaoming Ma

Yu Nozasa

Shuhei Kaneko

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 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 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 recovering the conjugated diene graft polymer obtained.

Conjugated diene graft polymer and method for producing the same

A diene rubber may give a crosslinked product or forming a rubber composition which has high levels of both ice grip performance and wet grip performance; a rubber composition may include the diene rubber; a tire member may be formed from the rubber composition or a crosslinked product thereof; and a tire may include the rubber composition or a crosslinked product thereof as at least a portion thereof. A resin modifier may include the diene rubber and give such a resin composition. A diene rubber may include butadiene units and an Mof 5,000 to 50,000, and may satisfy (i) to (iii): (i) β>0; (ii) β>40; and (iii) β/(β−40)≤2, wherein βis the mol % of 1,2-bonded butadiene units, and βis the mol % of specific structural units, both with respect to all butadiene units present in the diene rubber.

Diene rubber and rubber composition

A modified liquid diene rubber (A) has a functional group (a) derived from an acid anhydride, and satisfies all the requirements (I) to (III) below: (I) The functional group equivalent weight of the functional groups (a) is in the range of 400 to 3,500 g/eq. (II) The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 5,000 to 20,000. (III) The melt viscosity at 38&#xb0; C. is not less than 3 Pa&#xb7;s and X (K) is not less than 6100 K wherein X is the slope of a linear line passing through two points in a graph in which the two points are values of melt viscosity &#x3b7; (Pa&#xb7;s) at 38&#xb0; C. and 60&#xb0; C. measured with a Brookfield viscometer which are plotted as Ln[&#x3b7;/(Pa&#xb7;s)] on ordinate versus 1/T (K) on abscissa (with the proviso that T is temperature (K)).

Modified liquid diene rubbers

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Kamisu-shi, Japan

Yoshikazu Ueno