Low density polyethylene copolymer having excellent film processability and transparency

Patent metadata

Field	Value
Publication number	US-10508164-B2
Application number	US-201615546474-A
Country	US
Kind code	B2
Filing date	Dec 23, 2016
Priority date	Dec 23, 2015
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

The low density polyethylene copolymer according to the present invention is characterized in that as LCB (Long Chain Branch) is introduced into LLDPE, the melt strength is remarkably high even without blending with LDPE, and thus it can be advantageously applied to blown film processing and the like.

First claim

The invention claimed is:

1. A low density polyethylene copolymer which satisfies the following conditions:
a melt index (MI) of 0.5 to 1.5 g/10 min as measured according to ASTM D1238 (2.16 kg, 190° C.),
a density 0.910 to 0.930 g/cm 3 as measured according to ASTM D792,
a weight average molecular weight of 91,000 to 150,000, and
a melt strength (MS) of 70 to 100 mN,
wherein the low density polyethylene copolymer has η 0 (zero shear viscosity) of 140,000 P (poise) or more, and η 500 (viscosity measured at 500 rad/s) of 7,000 P (Poise) or less.

2. The low density polyethylene copolymer according to claim 1 ,
wherein the low density polyethylene copolymer has Mz (Z-average molecular weight) of 220,000 to 380,000.

3. The low density polyethylene copolymer according to claim 1 ,
wherein an LCB shift factor(α M )of the following Mathematical Formula 1-1 is 0.1 to 3.0:

α
M

=

(

η
0

3.4
×

10

-
15

×

Mw
3.6

-

⁢

⁢

8
⁢

4
,
000

⁢

3.4
×

10

-
15

×
125
,

381
3.6

)

×
3.4
×

10

-
2

[

Mathematical
⁢

⁢
Formula
⁢

⁢
1
⁢

-

⁢
1

]

in Mathematical Formula 1-1,
η 0 (zero shear viscosity) means a zero shear viscosity (unit: P) of the low density polyethylene copolymer, and Mw means a weight average molecular weight of the low density polyethylene copolymer.

4. The low density polyethylene copolymer according to claim 3 , which satisfies the following Mathematical Formula 2:
(1.6×(Mz/10 5 ) 2.8 +26×(α M ) 0.25 )<MS<(2.1×(Mz/10 5 ) 2.8 +28×(α M ) 0.25 )  [Mathematical Formula 2]

in Mathematical Formula 2,
Ms means the melt strength (mN) of the low density polyethylene copolymer and Mz means Z-average molecular weight (g/mol) of the low density polyethylene copolymer.

5. The low density polyethylene copolymer according to claim 1 ,
wherein MFRR(MFR 21.6 /MFR 2.16 ) is 25 to 37.

6. The low density polyethylene copolymer according to claim 1 ,
wherein Mz/Mw is 2.0 to 3.0.

7. The low density polyethylene copolymer according to claim 1 ,
wherein the molecular weight distribution (Mw/Mn) of 2.5 to 3.5.

8. The low density polyethylene copolymer according to claim 1 ,
wherein the low density polyethylene copolymer has a haze value of 20 or less as measured according to ISO 14782.

9. The low density polyethylene copolymer according to claim 1 ,
wherein the low density polyethylene copolymer is a copolymer of ethylene and an alpha-olefin having 3 to 20 carbon atoms.

10. The low density polyethylene copolymer according to claim 9 ,
wherein the alpha-olefin is one or more selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

11. The low density polyethylene copolymer according to claim 1 ,
wherein the low density polyethylene copolymer is prepared by using i) a hybrid catalyst containing a metallocene catalyst represented by the following Chemical Formula 1, and ii) a metallocene catalyst represented by the following Chemical Formula 2 or Chemical Formula 3:

in Chemical Formula 1,
M is Ti, Zr, or Hf,
X 1 and X 2 are the same as or different from each other and are each independently selected from halogen, a nitro group, an amido group, a phosphine group, a phosphide group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxyalkyl group having 2 to 20 carbon atoms, a silyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a sulfonate group having 1 to 20 carbon atoms, or a sulfone group having 1 to 20 carbon atoms,
T is C, Si, Ge, Sn, or Pb,
Q 1 and Q 2 are the same as or different from each other and are each independently selected from hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, a heterocycloalkyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkoxy alkyl group having 1 to 20 carbon atoms, a carboxylate having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 2

Assignees

• Lg Chemical Ltd

Inventors

• Kwon Oh Joo
• Cho Sol
• Lee Ki Soo
• Kwon Heon Yong
• Hong Dae Sik
• Park Sung Hyun
• Lee Myung Han

Classifications

• C08F2500/17

  Viscosity · CPC title

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08F2500/08

  Low density, i.e. < 0.91 g/cm3 · CPC title

• C08F4/65916

  supported on a carrier, e.g. silica, MgCl2, polymer · CPC title

• C08F2500/11

  Melt tension or melt strength · CPC title