Cross-linked Polyolefin Pipe Stabilizer System for Chlorinated Water

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Solution Overview

Problem

Conventional antioxidants in polyethylene pipes used for potable water applications are rapidly consumed by chlorinated water environments, leading to accelerated degradation, necessitating a new polymer matrix formulation to reduce antioxidant extraction and depletion.

Innovation Solution

Incorporating a primary stabilizer like thiodiethylene-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and a second stabilizer such as hindered amine light stabilizers or nanoparticles, like zinc oxide, into cross-linked polyolefin pipes to enhance long-term stability and resistance to oxidative degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional antioxidants are used in polyethylene pipes for potable water applications, then initial oxidation resistance is provided, but the antioxidants are rapidly consumed through catalyzed oxidation by chlorinated water, leading to accelerated degradation

Engineering Contradiction:
Improveoxidation resistanceVSAvoidlong term stability
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical parameters of the stabilizer system by introducing sulphur-containing hindered phenols with specific molecular structures (Irganox 1035, Anox 70) that have different reactivity characteristics toward chlorine compared to conventional antioxidants. This parameter change reduces the rate of catalyzed oxidation consumption while maintaining oxidation protection

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite stabilizer system combining multiple components: sulphur-containing hindered phenols as primary stabilizers, supplemented by other antioxidants and stabilizers. This composite approach provides synergistic protection where the combination of stabilizers offers superior long-term resistance to chlorinated water compared to single stabilizer systems

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If polyethylene is used for plastic pipes in potable water systems, then flexibility and long term stability are achieved, but exposure to chlorinated water at elevated temperatures and pressures leads to increased failure rates through catalyzed oxidation

Engineering Contradiction:
Improveflexibility in installationVSAvoidcatalyzed oxidation from chlorinated water
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The sulphur-containing hindered phenol stabilizers act as intermediary substances that preferentially react with chlorine and free radicals generated by chlorinated water, protecting the polyethylene polymer chains from oxidation. The stabilizer molecules serve as sacrificial intermediaries that consume the harmful oxidative species before they can attack the polymer structure

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful interaction between chlorine and polyethylene into a beneficial protective mechanism by introducing stabilizers that undergo controlled reaction with chlorine. The stabilizers absorb the harmful oxidative effect, transforming the potentially destructive chlorine-polyethylene reaction into a controlled stabilizer-chlorine reaction that protects the pipe material

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The combination of stabilizers significantly improves long-term stability and resistance to oxidative degradation in chlorinated water environments, extending the lifespan of polyethylene cross-linked pipes under elevated temperatures and pressures.

Implementation Method 1

long term stability including oxidation resistance to meet current codes and standards for potable water applications

Methodology Applied
Scientific EffectOxidation resistance: Oxidation

Implementation Method 2

extensive exposure to chlorine, and/or any of its water-soluble derivatives, at elevated temperatures and pressures, eventually leads to increased failure rates for plastic piping systems through catalyzed oxidation

Methodology Applied
Scientific EffectCatalyzed oxidation: Oxidation

Implementation Method 3

This may logically be achieved by lowering the rate of diffusion and, consequently, extraction and depletion of said entities

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP2220155B1Plastic pipe made of cross-linked polyolefin further comprising stabilizer (s)
Publication Date: 2015.03.04 UPONOR INNOVATION AB

AI summary

A plastic pipe is made of a cross-linked poiyolefin to be utilized in, but not limited to, potabie water applications. Certain antioxidants and stabilizers are added to a process for producing the plastic pipe. The added antioxidants and stabilizers remain as key components in the final plastic pipes, providing superior long term stability and resistance to oxidative degradation, the latter being caused by but not limited to, chlorinated water environments, At least a primary stabilizer is used in the material.