Patent ID: 8877857

Claim:
A polar group-containing copolymer obtainable by copolymerizing a conjugated diene compound and a polar group-containing vinyl compound, wherein a cis content of a double bond portion of the conjugated diene compound in the polar group-containing copolymer is 80 mol % or more, and wherein the polar group-containing vinyl compound is a compound represented by formula (I): wherein R 1 s each are hydrogen, a vinyl group, or a C1-C3 aliphatic hydrocarbon group, and may be the same as or different from each other; R 2 s each are hydrogen or a C1-C3 aliphatic hydrocarbon group and may be the same as or different from each other; R 3 is hydrogen or a C1-C8 aliphatic or alicyclic hydrocarbon group; X is a hydroxy group, —NR 2 , or a group represented by —Si(OR) k (R) 3-k wherein Rs each are hydrogen or a C1-C8 hydrocarbon group and may be the same as or different from each other; and k is an integer of 1, 2, or 3; n is an integer of 1 to 10; and the R 1 , R 2 , R 3 , a carbon atom linked to the R 2 , and/or a carbon atom linked to the R 3 may be bonded to each other to form a ring structure.