Polyethylene having high degree of crosslinking and crosslinked polyethylene pipe comprising the same

Patent metadata

Field	Value
Publication number	US-12173142-B2
Application number	US-202017427481-A
Country	US
Kind code	B2
Filing date	Feb 20, 2020
Priority date	Feb 20, 2019
Publication date	Dec 24, 2024
Grant date	Dec 24, 2024

Abstract

The present disclosure relates to a polyethylene having high degree of crosslinking and a crosslinked polyethylene pipe including the same. The polyethylene according to the present disclosure has a high content of ultra-high molecular weight, and thus a crosslinking rate is improved, and thus a sufficient degree of crosslinking is exhibited even when the crosslinking time is shortened, thereby exhibiting excellent strength and pressure resistance characteristics.

First claim

What is claimed is:

1. A polyethylene which satisfies:
a density of 0.940 g/cm 3 or more and 0.960 g/cm 3 or less as measured according to ASTM D792;
a number average molecular weight (Mn) of 20,000 g/mol or more and 70,000 g/mol or less;
a weight average molecular weight (Mw) of 150,000 g/mol or more and 350,000 g/mol or less;
a melt index (MI 21.6 ) of 1 g/10 min or more and g/10 min or less as measured at a temperature of 190° C. under a load of 21.6 kg according to ASTM D1238, and
an integration value in a region where log Mw value is 6.0 or more, of 4.5% or more relative to a total integration value, in a GPC curve graph in which x axis is log Mw and y axis is dw/dlog Mw.

2. The polyethylene according to claim 1 , wherein the integration value in a region where the log Mw value is 6.0 or more is 4.5% to 10% relative to the total integration value.

3. The polyethylene according to claim 1 , which has a polydispersity index (PDI, Mw/Mn) of 3.0 or more and 10.0 or less.

4. The polyethylene according to claim 1 , which is prepared by polymerizing an ethylene monomer in the presence of a hybrid metallocene catalyst comprising a first metallocene compound represented by Chemical Formula 1; and a second metallocene compound represented by Chemical Formula 3 in a molar ratio of 20:1 to 5:1,

in Chemical Formula 1,
Q 1 and Q 2 are the same as or different from each other, and each independently represent hydrogen, a halogen, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkoxyalkyl group, a C6 to C20 aryl group, a C7 to C20 alkylaryl group, or a C7 to C20 arylalkyl group;
B is carbon, silicon, or germanium;
M 1 is a Group 4 transition metal;
X 1 and X 2 are the same as or different from each other, and each independently represent a halogen, a C1 to C20 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group, a C7 to C20 alkylaryl group, or a C7 to C20 arylalkyl group;
one of C 1 or C 2 is represented by Chemical Formula 2a or Chemical Formula 2b, and the other of C1 or C2 is represented by Chemical Formula 2c;

in Chemical Formulas 2a, 2b and 2c,
R 1 to R 21 and R 1 ′ to R 13 ′ are the same as or different from each other, and each independently represent hydrogen, a halogen, a C1 to C20 alkyl group, a C1 to C20 haloalkyl group, a C2 to C20 alkenyl group, a C1 to C20 alkylsilyl group, a C1 to C20 silylalkyl group, a C1 to C20 alkoxysilyl group, a C1 to C20 alkoxy group, a C6 to C20 aryl group, a C7 to C20 alkylaryl group, or a C7 to C20 arylalkyl group, provided that at least one of R 9 to R 13 and R 9 ′ to R 13 ′ is a C1 to C20 haloalkyl group;
⋅ represents a site of binding to B; and
* represents a site of binding to M 1 ,

in Chemical Formula 3,
M 2 is a Group 4 transition metal;
C p1 and C p2 are the same as or different from each other, and each independently represent a cyclic compound selected from the group consisting of cyclopentadienyl, indenyl, 4,5,6,7-tetrahydro-1-indenyl and fluorenyl, one or more hydrogens of the cyclic compound are each independently substituted with any one substituent selected among a C1 to 20 alkyl, a C1 to C20 alkoxy, a C2 to C20 alkoxyalkyl, a C6 to C20 aryl, a C7 to C20 alkylaryl, or a C7 to C20 arylalkyl; and
X 3 and X 4 are the same as or different from each other, and each independently represent a halogen, a C1 to C20 alkyl, a C2 to C10 alkenyl, a C6 to C20 aryl, a C7 to C20 alkylaryl, or a C7 to C20 arylalkyl.

5. The polyethylene according to claim 4 , wherein R 1 to R 21 and R 1 ′ to R 13 ′ in Chemical Formulas 2a, 2b and 2c each independently represent hydrogen, a halogen, a C1 to C20 alkyl group, or a C1 to C20 haloalkyl group.

6. The polyethylene according to claim 4 , wherein the first metallocene compound is a compound represented by the Chemical Formula 1-1:

7. The polyethylene according to claim 4 , wherein the second metallocene compound is represented by one of the following structural formulas:

8. A crosslinked polyethylene pipe produced by a crosslinking reaction of the polyethylene of claim 1 , and a crosslinking agent.

9. The crosslinked polyethylene pipe according to claim 8 , wherein the crosslinking agent comprises at least one of di-t-butyl peroxide (DTBP), dicumyl peroxide, di-t-amyl peroxide, or 2,5-dimethyl-2,5-di (t-butylperoxy) hexane.

10. The crosslinked polyethylene pipe according to claim 8 , wherein a degree of crosslinking measured according to KS M ISO 10147 is 70% or more.

11. The crosslinked polyethylene pipe according to claim 8 , which is a PE-Xa pipe.

12. The crosslinked polyethylene pipe according to claim 8 , wherein a crosslinking rate (T90) measured according to ASTM D 5289 is 10 minutes or less.

13. The polyethylene according to claim 4 , wherein in Chemical Formula 1, Q1 and Q2 are each independently hydrogen, a halogen, a C1 to C20 alkyl group, or a C2 to C20 alkoxyalkyl group; B is silicon; and X 1 and X 2 are each independently a halogen or a C1 to C20 alkyl group.

14. The polyethylene according to claim 4 , wherein in Chemical Formula 3, Cp 1 and Cp 2 are each independently cyclopentadienyl or indenyl, and at least one hydrogen of the cyclopentadienyl or indenyl is substituted with any one substituent selected among a C1 to 20 alkyl or a C2 to C20 alkoxyalkyl; M 2 is zirconium (Zr); X 3 and X 4 are each independently a halogen or a C1 to C20 alkyl group.

15. The crosslinked polyethylene pipe according to claim 8 , wherein the crosslinking agent is included in an amount of 0.4 to 1 part by weight based on 100 parts by weight of the polyethylene.

Assignees

• Lg Chemical Ltd

Inventors

• Cho Sol
• Lee Hyunsup
• Kim Sun Mi
• Choi Yi Young
• Lee Myunghan
• Kim Yeonsoo

Classifications

• C08F10/02 Primary

  Ethene · CPC title

• C08F110/02 Primary

  Ethene · CPC title

• C08L2207/068

  Ultra high molecular weight polyethylene · CPC title

• C08L2203/18

  used for pipes · CPC title

• C08K5/14

  Peroxides · CPC title