Polyolefin
This invention relates to polyolefin. More specifically, this invention relates to polyolefin that may exhibit improved mechanical properties such as excellent drop impact strength.
1 . Polyolefin satisfying requirements of 1) to 3):
1) density measured according to ASTM D1505 being 0.915 g/cm 3 to 0.930 g/cm 3 ;
2) melt index (MI) measured at 190° C., under load of 2.16 kg according to ASTM D1238 being 0.5 to 1.5 g/10 min; and
3) by Successive Self-nucleation and Annealing (SSA) analysis, a rate of chains having ASL (Average Ethylene Sequence Length) of 22 nm or more being 16 wt % or more based on a total chains, and a rate of chains having Average Ethylene Sequence Length (ASL) of 8 nm or less being 38 wt % or more based on the total chains.
2 . The polyolefin according to claim 1 , wherein the SSA is conducted using differential scanning calorimeter, by heating the polyolefin to the first heating temperature of 120 to 124° C., maintaining for 15 to 30 minutes, and then, cooling to 28 to 32° C., and while decreasing heating temperature by stages with (n+1) th heating temperature being 3 to 7° C. lower than nth heating temperature, repeating heating-annealing-quenching until the final heating temperature becomes 50 to 54° C., and finally, raising the temperature from 30° C. to 160° C.
3 . The polyolefin according to claim 1 , wherein Short Chain Branch (SCB) content is 22/1000 C or more.
4 . The polyolefin according to claim 1 , wherein polydispersity index (PDI) defined as Mw/Mn is 3.3 to 4.0, wherein Mw is a weight average molecular weight, and Mn is a number average molecular weight.
5 . The polyolefin according to claim 1 , wherein dart drop impact strength measured according to ASTM D 1709, Method A, after preparing a polyolefin film having BUR 2.3, and a film thickness of 55 to 65 μm using a film applicator, is 1,500 g or more.
6 . The polyolefin according to claim 1 , wherein the polyolefin comprises a copolymer of ethylene and an alpha olefin.
7 . The polyolefin according to claim 6 , wherein the alpha olefin comprises one or more selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, norbornene, norbornadiene, ethylidene norbordene, phenyl norbordene, vinyl norbordene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methyl styrene, divinylbenzene, and 3-chloromethyl styrene.
8 . The polyolefin according to claim 1 , wherein the polyolefin is prepared by polymerizing olefin monomers, in the presence of a hybrid supported metallocene catalyst comprising one or more first metallocene compounds selected from compounds represented by Chemical Formula 1; one or more second metallocene compounds selected from compounds represented by Chemical Formula 2; and a carrier supporting the first and second metallocene compounds:
wherein in the Chemical Formula 1,
M is a Group 4 transition metal,
X 1 and X 2 are identical to or different from each other, and are each independently, hydrogen, halogen, C 1-20 alkyl, or QCOO—, and Q is C 1-20 alkyl,
A is carbon, silicon or germanium,
R 1 and R 2 are identical to or different from each other, and are each independently, C 1-20 alkyl, C 2-20 alkenyl, C 6-30 aryl,
R 3 to R 6 are identical to or different from each other, and are each independently, hydrogen, C 1-20 alkyl, C 2-20 alkenyl, C 6-30 aryl, C 7-30 alkylaryl, or C 7-30 arylalkyl,
R 7 and R 7 ′ are identical to or different from each other, and are each independently, C 1-20 alkyl, C 2-20 alkenyl, C 6-30 aryl, or C 2-20 alkoxy alkyl, and
E is one selected from the group consisting of sulfur(S), oxygen (O) and selenium (Se),
wherein in Chemical Formula 2,
M′ is a Group 4 transition metal,
A′ is carbon, silicon or germanium,
X 3 and X 4 are identical to or different from each other, and are each independently, halogen, or C 1-20 alkyl,
R 8 to R 11 are identical to or different from each other, and are each independently, hydrogen, C 1-20 alkyl, C 2-20 alkenyl, C 6-20 aryl, C 7-20 alkylaryl, C 7-20 arylalkyl, or two or more neighboring substituents of R 8 to R 11 are linked to each other to form a substituted or unsubstituted aliphatic ring, aromatic ring, or hetero aromatic ring comprising one or more selected from the group consisting of N, O and S,
R 12 and R 12 ′ are identical to or different from each other, and are each independently, C 1-20 alkyl, C 2-20 alkenyl, C 6-30 aryl, or C 2-20 alkoxy alkyl, and
R 13 is C 1-20 alkyl, C 2-20 alkenyl, or C 6-30 aryl.
9 . The polyolefin according to claim 8 , wherein the compound represented by Chemical Formula 1 is one selected from compounds represented by the following structural formulas:
wherein in the structural formulas,
Me denotes methyl,
Et denotes ethyl,
nPr denotes n-propyl,
Hx denotes n-hexyl,
Ph denotes phenyl, and
t-Bu denotes tert-butyl.
10 . The polyolefin according to claim 8 , wherein the compound represented by Chemical Formula 2 is one selected from compounds represented by the following structural formulas:
11 . The polyolefin according to claim 8 , wherein a mole ratio of the first and second metallocene compounds is 1:1 to 1:10.
12 . The polyolefin according to claim 8 , wherein the carrier comprises silica, alumina, magnesia, or a mixture thereof.