Olefin block copolymer

1. A method of producing an olefin block copolymer, comprising:

subjecting ethylene or propylene and an α-olefin to copolymerization at a temperature of 70 to 150° C. in the presence of a catalyst composition comprising a metallocene catalyst having a Group IV transition metal and a Lewis base functional group, and a cocatalyst having a Lewis acid element and an organic functional group, wherein the metallocene catalyst comprises a metallocene compound of Chemical Formula 1:

in Chemical Formula 1, R1 to R17 are the same with or different from each other, and are independently hydrogen, a halogen, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C6-C20 aryl group, a C7-C20 alkylaryl group, or a C7-C20 arylalkyl group, respectively, L is a straight or branched chain C1-C10 alkylene group, D is —O—, —S— or —N(R)—, wherein R is hydrogen, a halogen, a C1-C20 alkyl group, a C2-C20 alkenyl group, or a C6-C20 aryl group, A is hydrogen, a halogen, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C6-C20 aryl group, a C7-C20 alkylaryl group, a C7-C20 arylalkyl group, a C2-C20 alkoxy alkyl group, a C2-C20 heterocyclic alkyl group, or a C5-C20 heteroaryl group, and when the D is —N(R)—, R can be linked with A to form a heterocycle comprising nitrogen, for example, a five to eight membered heterocycle such as piperidinyl or pyrrolidinyl moiety, M is a Group IV transition metal, X1 and X2 are the same with or different from each other, and are independently a halogen, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C6-C20 aryl group, a nitro group, an amido group, a C1-C20 alkylsilyl group, a C1-C20 alkoxy group, or a C0-C20 sulfonate group, respectively;

wherein at the copolymerization temperature, there occur alternatively between the metallocene catalyst and the cocatalyst a first state in which the Lewis base functional group and the Lewis acid element form an acid-base bond and a second state in which the metallocene catalyst and the cocatalyst has no interaction therebetween;

wherein the Group IV transition metal of the metallocene catalyst and the organic functional group of the cocatalyst do interaction with each other in the first state;

wherein 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, and the olefin block copolymer comprises polymer chains comprising 20 to 100 short-chain branches (SCBs) per 1,000 carbon atoms; and

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 values of the molecular weight X and the maximum peak molecular weight Mp of the block copolymer.

2. The method of producing an olefin block copolymer in accordance with claim 1 , wherein the α-olefin is at least one 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 and 1-hexadecene.

3. The method of producing an olefin block copolymer in accordance with claim 1 , wherein the cocatalyst comprises a compound of Chemical Formula 3:

—[Al(R18)-O] n -  [Chemical Formula 3]

in Chemical Formula 3, R18s are the same with or different from each other, and are independently a C1-C20 hydrocarbon; or a C1-C20 hydrocarbon substituted with a halogen; and n is an integer of at least two.

4. The method of producing an olefin block copolymer in accordance with 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.

5. The method of producing an olefin block copolymer in accordance with 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.

6. The method of producing an olefin block copolymer in accordance with 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.

7. The method of producing an olefin block copolymer in accordance with claim 6 , 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.

8. The method of producing an olefin block copolymer in accordance with claim 6 , wherein the olefin block copolymer comprises 20 to 95 mol. % of the hard segment and 5 to 80 mol. % of the soft segment.

9. The method of producing an olefin block copolymer in accordance with claim 6 , 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.