Polyethylene and preparation method thereof
Provided are a polyethylene which is improved in terms of total volatile organic compounds (TVOCs) generated by low molecular weight polymers, thereby being suitable for fiber production, and a method of preparing the same.
1 . A polyethylene, of which
a melt index according to (ASTM D 1238 measured at 190° C. under loaded of 2.16 kg is 15 g/10 min to 40 g/10 min,
a melt flow rate ratio (MFRR) of MI 5 /MI 2.16 is 2.3 to 2.7,
an integral value in a region where Log Mw is 3.0 or less in a GPC curve, wherein an x-axis is the log Mw and a y-axis is dw/d log Mw, is 0.8% to 1.8% of a total integral value, and
a content of a linear hydrocarbon having 3 to 32 carbon atoms based on 1 g of the polyethylene is 600 ppm or less, when a peak area of the linear hydrocarbon having 3 to 32 carbon atoms is converted into a ratio with respect to a peak area of the polyethylene in a GC-FID graph obtained through gas chromatography/flame ionization detector analysis using GC-FID, Inlet, Detector temperature at 300° C., a residence time of 20 minutes.
2 . The polyethylene of claim 1 , wherein the integral value is 0.9% to 1.5% of the total integral value.
3 . The polyethylene of claim 1 , wherein a molecular weight distribution (Mw/Mn) is 2.0 to 2.6.
4 . The polyethylene of claim 1 , wherein a weight average molecular weight is 38000 g/mol to 65000 g/mol.
5 . The polyethylene of claim 1 , wherein the content of a linear hydrocarbon having 3 to 32 carbon atoms based on 1 g of the polyethylene is 80 ppm to 600 ppm.
6 . The polyethylene of claim 1 , wherein a density measured with (ASTM D 1505 at 23° C. is 0.945 g/cm 3 to 0.965 g/cm 3 .
7 . The polyethylene of claim 1 , wherein the polyethylene comprises a homopolymer of ethylene or a copolymer of a C 4-20 alpha-olefin monomer and ethylene.
8 . A method of preparing the polyethylene of claim 1 , comprising polymerizing ethylene in the presence of a catalyst composition including a metallocene compound represented by Chemical Formula 1:
wherein in Chemical Formula 1,
B is boron,
M is a Group 4 transition metal,
R 1 to R 4 are each independently hydrogen, C 1-20 alkyl, C 3-20 cycloalkyl, or C 6-20 aryl, or R 1 and R 2 or R 3 and R 4 are connected to each other to form a substituted or unsubstituted C 6-60 aromatic ring,
R 5 and R 6 are each independently C 1-20 alkyl, C 3-20 cycloalkyl, or C 6-20 aryl, or R 5 and R 6 are connected to each other to form a C 3-60 aliphatic ring or a C 6-60 aromatic ring,
X 1 and X 2 are each independently C 1-20 alkyl or —O(CO)R′, wherein R′ is C 1-20 alkyl,
Q is a substituted or unsubstituted C 2-60 hetero ring including any one or more selected from the group consisting of N, O, and S,
Y and Y′ are elements constituting Q,
Y is N, O, or S, and
Y′ is an element of Q, and is adjacent to Y, and is N or C.
9 . The method of claim 8 , wherein R 1 to R 4 are each independently hydrogen, or methyl, or R 1 and R 2 or R 3 and R 4 are connected to each other to form a benzene ring or a 1,2,3,4-tetrahydronaphthalene ring, wherein the benzene ring or the 1,2,3,4-tetrahydronaphthalene ring is unsubstituted or substituted with one substituent to four substituents selected from the group consisting of methyl, tert-butyl, and 4-tert-butyl phenyl.
10 . The method of claim 8 , wherein R 5 and R 6 are each independently methyl or phenyl, or R 5 and R 6 are connected to each other to form a cyclooctane ring.
11 . The method of claim 8 , wherein the compound represented by Chemical Formula 1 is any one of compounds represented by the following structural formulae:
12 . The method of claim 8 , wherein the catalyst composition further includes one or more cocatalyst compounds selected from the group consisting of compounds represented by Chemical Formula 2 to Chemical Formula 4:
—[Al(R 10 )—O] a — Chemical Formula 2
wherein in Chemical Formula 2,
R 10 is halogen; or C 1-20 hydrocarbyl substituted or unsubstituted with halogen; and
a is an integer of 2 or more,
D(R 11 ) 3 Chemical Formula 3
wherein in Chemical Formula 3,
D is aluminum or boron; and
R 11 is halogen; or C 1-20 hydrocarbyl substituted or unsubstituted with halogen,
[L-H] + [ZA 4 ] − or [L] + [ZA 4 ] Chemical Formula 4
wherein in Chemical Formula 4,
L is a neutral or cationic Lewis base;
H is a hydrogen atom;
Z is a group 13 element; and
A's are each independently C 6-40 aryl or C 1-20 alkyl, wherein C 6-40 aryl or C 1-20 alkyl is unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, C 1-20 alkyl, C 1-20 alkoxy, and C 6-40 allyloxy.