Catalyst composition for polymerizing polyolefin, method for producing polyolefin, and polyolefin resin
A catalyst composition for polymerizing a polyolefin having excellent processability and impact strength, a process for producing a polyolefin and a polyolefin resin thereof are disclosed. The catalyst composition comprises at least one first organometallic compound of following formula 1; at least one second organometallic compound of following formula 2; and aluminoxane. The polyolefin resin satisfies following properties (i) to (iv) and (vi), (i) melt flow index (ASTM D1238), measured at 190° C., under a load of 2.16 kg: 0.1 to 1.5 g/10 min, (ii) density: 910 to 930 kg/m 3 , (iii) the ratio (Mw/Mn), as measured by gel permeation chromatography (GPC): 3.0 to 7.0, (iv) the ratio (Mz/Mw), as measured by GPC: 2.2 to 4.5, and (vi) when the TREF curve of multimodal distribution is deconvoluted, the area of TREF curve having a peak at 50 to 74° C. is 40 to 75% of the total area of the TREF curve.
1. A method for producing a polyolefin comprising polymerizing ethylene and an alpha-olefin comonomer in the presence of a polyolefin polymerization catalyst composition,
wherein the catalyst composition comprises:
at least one first organometallic compound represented by following Formula 1;
at least one second organometallic compound represented by following Formula 2; and
aluminoxane,
( L 1)( L 2)( X 1)( X 2) M 1 [Formula 1]
in Formula 1, M1 is hafnium (Hf); (L1) and (L2) each is a cyclopentadienyl group having an alkyl substituent of 3 to 4 carbon atoms; (X1) and (X2) each is independently F, Cl, Br, I or a hydrocarbon group of 1 to 10 carbon atoms;
in Formula 2, R 1 is a methyl group and R 2 to R 6 each is independently hydrogen or an alkyl group laving 1 to 10 carbon atoms; X 1 and X 2 each is independently F, Cl, Br, I or a hydrocarbon group of 1 to 10 carbon atoms,
wherein the polyolefin satisfies following properties (i) to (iv) and (vi),
(i) melt flow index (measured according to ASTM D1238), measured at 190° C., under a load of 2.16 kg: 0.1 to 1.5 g/10 min;
(ii) density: 910 to 930 kg/m 3 ;
(iii) ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn), as measured by gel permeation chromatography: 3.2 to 6.0;
(iv) ratio (Mz/Mw) of Z-average molecular weight (Mz) to weight-average molecular weight (Mw), as measured by gel permeation chromatography: 2.4 to 3.4;
(vi) when a TREF (temperature rising elution fractionation) curve of multimodal distribution is deconvoluted, an area of the TREF curve having a peak at 50 to 74° C. is 40 to 75% of a total area of the TREF curve of multimodal distribution.
2. The method for producing a polyolefin as claimed in claim 1 , wherein the alpha-olefin comonomer is at least one selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and mixtures thereof, and an amount of alpha-olefin comonomers is from 1 to 4 mol %, with respect to the ethylene and alpha-olefin comonomer.
3. The method for producing a polyolefin as claimed in claim 1 , wherein when deconvolution of the TREF curve of multimodal distribution is performed, a number of peaks is 2 to 5.
4. The method for producing a polyolefin as claimed in claim 1 , wherein the polyolefin further satisfies following property (v),
(v) in the TREF curve of multimodal distribution, a weight percentage (wt %) sum (A) and density (D, unit: kg/m 3 ) of components eluted at a temperature range of 43 to 71° C. (A) satisfy following Equation 1
A>− 2.5*( D )+2325 [Equation 1].
5. The method for producing a polyolefin as claimed in claim 1 , the polyolefin resin further satisfies following properties (vii) and (viii),
(vii) COI (Comonomer Orthogonal Index) value calculated by the following Equation 2: 4.5 to 18
comonomer
orthogonal
index
(
COI
)
=
SCB
number
in
Mz
-
SCB
number
in
Mn
log
Mz
-
log
Mn
[
Equation
2
]
in Equation 2, Mz and Mn are Z-average molecular weight and number average molecular weight of the polyolefin, measured by gel permeation chromatography equipped with an IR detector, respectively, and a number of SCB (Short Chain Branch)s in Mz and a number of SCBs in Mn represent a number of average side branches derived from comonomers per 1000 carbons in Z-average molecular weight (Mz) and number-average molecular weight (Mn), respectively,
(viii) an average SCBs number per 1,000 carbons (B), and density (D, unit: kg/m 3 ) over an entire molecular weight range satisfy following Equation 3
B>− 0.6*( D )+563 [Equation 3].