# US 7,744,972 B2 · Stabilized polyethylene material

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- Number: US 7,744,972 B2
- Document ID: US7744972B2
- Status: Granted
- Kind: B2
- Application number: 10/579,360
- Filed: 2004-12-03
- Published: 2007-04-26
- Granted: 2010-06-29
- Earliest claimed: 2004-12-03
- Assignees: Dow Global Technologies LLC
- Inventors: Thoi H. Ho; Detlef Schramm; Pak-Meng Cham; Kalyan Sehanobish
- Web page: https://patentgrep.com/patent/US7744972B2

## CPC

- F16L 11/06: with homogeneous wall (F16L11/11 takes precedence)
- C08K 5/13: Phenols; Phenolates
- C08K 5/49: Phosphorus-containing compounds {(C08K5/0091 takes precedence)}
- C08K 2201/014: Additives containing two or more different additives of the same subgroup in C08K
- C08L 23/04: Homopolymers or copolymers of ethene
- Y10T 428/139: Open-ended, self-supporting conduit, cylinder, or tube-type article
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Stabilized polyethylene materials which offer an advantageously balanced combination of thermal, mechanical and processing properties, and which maintain their physical properties in chlorinated water environments are disclosed. The materials include an antioxidant system with components to provide extraction resistance in hot water environments and additionally provides oxidation resistance to both chlorine in the water interior of the pipe and oxygen in contact with the pipe's exterior.

## Claims

### Claim 1

A pipe consisting essentially of:
an ethylene alpha-olefin interpolymer, wherein said ethylene alpha-olefin interpolymer has a density in the range of 0.925 to 0.965 g/cc, a melt index (I2) in the range of 0.05 to 5 g/10 minutes; and
an antioxidant system, wherein said antioxidant system consist essentially of;
from 500 to 5000 ppm of 3,3′,3″, 5,5′,5″-hexa-tert-butyl-α,α′,α″-(mesitylene-2,4,6-triyl)tri-p-cresol;
from at least 300 to 5000 ppm of Pentaerythritol Tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), Octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate, or combinations thereof;
optionally one or more metal deactivators;
wherein said pipe has an F time in Jana Laboratories Procedure APTF-2 of at least 1000 hours, under the following conditions: pH 6.8 (±0.1); Chlorine 4.1 mg/L (±0.1); Nominal ORP 830 mV; fluid temperature 110° C. (±1); air temperature 110° C. (±1); pressure 70 psig (±1); flow rate 0.1 US gallons/min (±10 percent).

### Claim 2 (depends on 1)

The pipe of claim 1, wherein the ethylene alpha-olefin interpolymer is multimodal.

### Claim 3 (depends on 1)

The pipe of claim 1, wherein the ethylene alpha-olefin interpolymer has a density in the range of 0.940 to 0.965 g/cc.

### Claim 4 (depends on 1)

The pipe of claim 1, wherein said pipe has an F time in the range of greater than 1200 hours.