# US 10,501,613 B2 · Low-sag polyethylene pipes and methods thereof

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,501,613 B2
- Document ID: US10501613B2
- Status: Granted
- Kind: B2
- Application number: 15/400,562
- Filed: 2017-01-06
- Published: 2018-02-01
- Granted: 2019-12-10
- Earliest claimed: 2016-07-29
- Assignees: Equistar Chemicals, LP
- Applicants: Equistar Chemicals, LP
- Inventors: Harilaos Mavridis; Chun D. Lee; Steven W. Horwatt; Sameer D. Mehta
- Web page: https://patentgrep.com/patent/US10501613B2

## CPC

- C08L 23/06: Polyethylene
- B29C 48/022: {characterised by the choice of material}
- B29C 48/09: Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
- C08L 23/14: Copolymers of propene (C08L23/16 takes precedence)
- F16L 9/12: of plastics with or without reinforcement (F16L9/16 - F16L9/22 take precedence)
- F16L 9/127: the walls consisting of a single layer
- B29K 2023/065: {HDPE, i.e. high density polyethylene}
- B29K 2023/0675: {HMWPE, i.e. high molecular weight polyethylene}
- B29K 2023/0691: {PEX, i.e. crosslinked polyethylene}
- B29L 2023/22: {Tubes or pipes, i.e. rigid (bent tubes not for use as pipe couplings B29L2023/004)}
- C08L 2203/18: used for pipes
- C08L 2205/02: containing two or more polymers of the same C08L -group
- C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
- C08L 2207/062: HDPE
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

The present disclosure relates to pipes comprising bimodal high molecular weight high density polyethylene which has been extruded in the presence of one or more organic peroxides that are present in an amount ranging from 30 ppm to 200 ppm. The pipe has an improved long-term hydrostatic strength. Also provided are methods for preparing pipes having these characteristics.

## Claims

### Claim 1

An extruded pipe comprising: (1) a bimodal high molecular weight high density polyethylene having a density ranging from about 0.9460 g/cm3 to about 0.9520 g/cm3, and (2) a polypropylene random copolymer containing one or more organic peroxides,
wherein the pipe was extruded in the presence of about 30 ppm to about 200 ppm of one or more organic peroxides,
wherein the one or more organic peroxides has a half-life of 1 hour at a temperature in the range of about 125° C. to about 145° C., and
the extruded pipe has a long-term hydrostatic strength tF/tR ratio of about 1.5 or greater when determined at 23° C. and 12 MPa and/or at 23° C. and 11.5 MPa, where tF is the time-to-failure of the pipe and tR is the time-to-failure of a comparative pipe which has not been extruded with organic peroxide.

### Claim 2 (depends on 1)

The extruded pipe of claim 1, wherein the organic peroxide is present in an amount ranging from about 40 ppm to about 150 ppm.

### Claim 3 (depends on 1)

The extruded pipe of claim 1, wherein the long-term hydrostatic strength tF/tR ratio is about 2.0 or greater when determined at 23° C. and 12 MPa and/or at 23° C. and 11.5 MPa.

### Claim 4 (depends on 1)

The extruded pipe of claim 1, wherein the organic peroxide comprises:
a half-life of 1 hour at a temperature in the range of about 130° C. to about 140° C.;
a half-life of 0.1 hour at a temperature in the range of about 145° C. to 165° C.; and
a molecular weight in the range of about 175 g/mol to about 375 g/mol.

### Claim 5 (depends on 1)

The extruded pipe of claim 1, wherein the organic peroxide is selected from the group consisting of dicumyl peroxide, di(tert-butylperoxyisopropyl)benzene(s), 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl cumyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne.

### Claim 6 (depends on 1)

The extruded pipe of claim 1, wherein the long-term hydrostatic strength tF/tR ratio is determined by measuring the time-to-failure of the pipe at 12 MPa or at 11.5 MPa, and calculating the tF/tR ratio, using
tR=100 hours×[1+(density−0.947)×1340] for determinations at 12 MPa, and
tR=560 hours×[1+(density−0.947)×1340] for determinations at 11.5 MPa.

### Claim 7 (depends on 1)

The extruded pipe of claim 1, which has one or more of the following properties:
a sag value of about 20 or less;
a PENT result of about 500 hours or more; and
a Charpy impact energy of about 10 kJ/m2 or more.

### Claim 8 (depends on 7)

The extruded pipe of claim 7, which has one or more of the following properties:
a density in the range of about 0.9470 g/cm3 to about 0.9510 g/cm3;
a sag value of about 15 or less;
a PENT result of about 1000 hours or more; and
a Charpy impact energy of about 11 kJ/m2 or more.

### Claim 9 (depends on 8)

The extruded pipe of claim 8, further comprising two or more of the properties, wherein the organic peroxide is present in an amount ranging from about 45 ppm to about 125 ppm in the bimodal high density polyethylene, and wherein the long-term hydrostatic strength tF/tR ratio is about 2.0 or greater when determined at 23° C. and 12 MPa and/or at 23° C. and 11.5 MPa.

### Claim 10 (depends on 7)

The extruded pipe of claim 7, further comprising two or more of the properties, wherein the organic peroxide is present in an amount ranging from about 40 ppm to about 150 ppm in the bimodal high density polyethylene, and wherein the long-term hydrostatic strength tF/tR ratio is about 2.0 or greater when determined at 23° C. and 12 MPa and/or at 23° C. and 11.5 MPa.