OLEFIN BLOCK COPOLYMER
The present description relates to an olefin block copolymer with excellences in elasticity, heat resistance, and processability. The olefin block copolymer comprises a plurality of blocks or segments, each comprising an ethylene or propylene repeating unit and an α-olefin repeating unit at different mole fractions. The olefin block copolymer comprises polymer chains containing 20 to 100 short-chain branches (SCBs) per 1,000 carbon atoms. A point where a first derivative of the number Y of the SCBs per 1,000 carbon atoms of each polymer chain with respect to the molecular weight X of the polymer chain is 0 exists between the minimum and maximum values of the molecular weight X.
1 . An olefin block copolymer comprising a plurality of blocks or segments, each comprising an ethylene or propylene repeating unit and an α-olefin repeating unit at different mole fractions,
wherein the olefin block copolymer comprises polymer chains comprising 20 to 100 short-chain branches (SCBs) per 1,000 carbon atoms,
wherein a point where a first derivative of the number Y of the SCBs per 1,000 carbon atoms of each polymer chain with respect to the molecular weight X of the polymer chain is 0 exists between the minimum and maximum values of the molecular weight X.
2 . The olefin block copolymer as claimed in claim 1 , wherein the point where the first derivative is 0 exists in a region below the maximum peak molecular weight Mp of the block copolymer.
3 . The olefin block copolymer as claimed in claim 1 , wherein the first derivative is a positive number in a region where the molecular weight X is less than at the point where the first derivative is 0.
4 . The olefin block copolymer as claimed in claim 1 , wherein the first derivative is a negative number in a region where the molecular weight X is greater than at the point where the first derivative is 0.
5 . The olefin block copolymer as claimed in claim 1 , wherein the olefin block copolymer has a crystallization temperature Tc of 95 to 120° C.
6 . The olefin block copolymer as claimed in claim 1 , wherein the olefin block copolymer has a melting temperature Tm of 110 to 135° C.
7 . The olefin block copolymer as claimed in claim 1 , wherein the olefin block copolymer comprises a hard segment comprising a first mole fraction of the α-olefin repeating unit, and a soft segment comprising a second mole fraction of the α-olefin repeating unit,
wherein the second mole fraction is greater than the first mole fraction.
8 . The olefin block copolymer as claimed in claim 7 , wherein the mole fraction of the α-olefin repeating unit contained in the entire block copolymer has a value between the first and second mole fractions.
9 . The olefin block copolymer as claimed in claim 7 , wherein the olefin block copolymer comprises 20 to 95 mol. % of the hard segment and 5 to 80 mol. % of the soft segment.
10 . The olefin block copolymer as claimed in claim 7 , wherein the hard segment has a higher value than the soft segment in at least one property of the degree of crystallization, density, and melting temperature.
11 . The olefin block copolymer as claimed in claim 1 , wherein the olefin block copolymer comprises 80 to 98 mol. % of the ethylene or propylene repeating unit and a remaining content of the α-olefin repeating unit.
12 . The olefin block copolymer as claimed in claim 1 , wherein the olefin block copolymer has a density of 0.85 to 0.92 g/cm 3 .
13 . The olefin block copolymer as claimed in claim 1 , wherein the olefin block copolymer has a weight average molecular weight of 5,000 to 3,000,000 and a molecular weight distribution of 2.5 to 6.
14 . The olefin block copolymer as claimed in claim 1 , wherein the α-olefin repeating unit is a repeating unit derived from at least one α-olefin selected from the group consisting of 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-itocene.