Photo-Crosslinked Polyolefin Pipe With Low Additive Leaching

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Solution Overview

Problem

Existing polyolefin pipes used for drinking water applications face challenges with additive leaching, which can contaminate water and fail to meet stringent standards for long-term stability and resistance to chlorine, leading to potential toxicity and reduced pipe lifespan.

Innovation Solution

A polymeric pipe formed using a polyolefin structural polymer, a photoinitiator, and a scavenger, processed through co-rotating twin screw extrusion followed by photo-induced crosslinking, which reduces leaching and enhances oxidative resistance, meeting or exceeding current standards for drinking water applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polyolefin pipes are used for drinking water applications, then they provide basic water conveyance functionality, but they suffer from additive leaching that contaminates water and fails to meet stringent standards for long-term stability and chlorine resistance

Engineering Contradiction:

Improvelong-term stability and chlorine resistanceVSAvoidadditive leaching

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent removes harmful conventional additives (photoinitiators, stabilizers, crosslinking agents) from the pipe formulation entirely, replacing them with a peroxide-free crosslinking system that uses only safe, food-grade components. This extraction of harmful substances eliminates the source of leaching while maintaining crosslinked polyethylene performance and reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the chemical composition parameters by using alternative safe crosslinking agents and peroxide-free formulations, transforming the pipe material from one that leaches additives to one that meets NSF 61 drinking water standards while maintaining oxidative resistance and long-term stability.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If crosslinked polyethylene (PEX) is used to improve long-term stability and oxidation resistance, then the pipe lifespan is extended, but conventional crosslinking chemistries introduce additives that leach and contaminate water

Engineering Contradiction:

Improvepipe lifespanVSAvoidchemical residual leaching

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potentially harmful crosslinking process into a beneficial one by using safe, food-grade crosslinking agents that do not leach. The crosslinking chemistry itself is transformed from harmful (peroxide-based with residual leaching) to beneficial (using safe alternatives that meet drinking water standards), thereby extending pipe lifespan without contamination.

Inventive Principle:

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

Solution Approach 2:

The invention creates a composite material system that combines crosslinked polyethylene structure with safe, non-leaching crosslinking agents and stabilizers, achieving both extended durability and drinking water safety compliance through carefully selected material combinations.

Inventive Principle:

Principle #40Composite materials

3Reliability

If stringent drinking water standards (NSF 61, ASTM F2023) are met to ensure safety, then water quality is protected, but pipe formulation becomes highly restricted limiting available additives for stability and performance

Engineering Contradiction:

Improvedrinking water safety complianceVSAvoidformulation flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent achieves multi-functionality by using a single safe crosslinking agent system that simultaneously provides crosslinking, stabilization, and drinking water safety compliance. This universal approach eliminates the need for multiple separate additives (photoinitiators, stabilizers, crosslinking agents) and provides all necessary functions within NSF 61 and ASTM F2023 compliant formulations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 process results in pipes with significantly reduced chemical residual leaching, improved long-term stability, and enhanced resistance to chlorine, ensuring compliance with NSF 61 and ASTM F2023 standards, while maintaining excellent mechanical properties and burst strength.

Implementation Method 1

processed through co-rotating twin screw extrusion followed by photo-induced crosslinking

Methodology Applied

Scientific EffectPhoto-induced crosslinking: Photopolymerisation

Implementation Method 2

co-rotating twin screw extrusion

Methodology Applied

Scientific EffectExtrusion: Extrusion

Data Source

PatentEP2992044B1Polyolefin pipe

Publication Date: 2022.01.12 UPONOR INNOVATION AB

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AI summary

This invention relates to a polymeric pipe, and more particularly a polymeric pipe where the pipe comprises a crosslinked polyolefin formed from extruded polyolefin comprising a photoinitiator and a reactive extrusion species. More particularly, this invention relates to the manufacturing of plastic pipes and tubing by utilizing co-rotating twin screw extrusion combined with photo-induced crosslinking, of thermoplastic polymers such as polyethylene, to produce PEX pipes and tubing.