Photo-Induced Crosslinked Polyolefin Pipe for Drinking Water

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Solution Overview

Problem

Existing polyolefin pipes used for drinking water applications face challenges with leaching of additives, which can contaminate the water and fail to meet stringent standards for long-term stability and resistance to chlorine, leading to unpredictable effects on consumers and reduced pipe lifespan.

Innovation Solution

A process utilizing co-rotating twin screw extrusion combined with photo-induced crosslinking, employing specific photoinitiators and co-agents to produce crosslinked polyolefin pipes with reduced leaching of chemical residuals, enhanced oxidative resistance, and improved mechanical properties, 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 transport functionality, but they suffer from leaching of additives that contaminate water and fail to meet stringent standards for long-term stability and resistance to chlorine

Engineering Contradiction:

Improvelong-term stability and resistance to chlorineVSAvoidleaching of additives

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by modifying the chemical structure of the polyolefin through controlled crosslinking. By adjusting crosslinking density and using specific crosslinking agents, the pipe material achieves enhanced resistance to chlorine and reduced additive leaching while maintaining water transport functionality. This transforms the material properties to meet stringent drinking water standards.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining polyolefin with crosslinking agents and functional additives to create a multi-component system. This composite structure provides both the base polymer matrix for water transport and additional functional phases that resist chlorine degradation and minimize leaching, thereby improving reliability without generating harmful factors.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If crosslinking is used to improve long-term stability and oxidation resistance, then pipe lifespan is extended, but the complexity of the manufacturing process increases

Engineering Contradiction:

Improvepipe lifespanVSAvoidmanufacturing process complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by incorporating crosslinking agents and functional additives during the extrusion process itself, rather than requiring separate post-processing steps. The co-rotating twin screw extruder enables in-line crosslinking, where the complex chemical reactions are initiated and controlled within the extruder, simplifying the overall manufacturing process while extending pipe lifespan.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional mechanical crosslinking methods (such as high-pressure autoclaving or steam treatment) with a chemical crosslinking approach initiated during extrusion. By using peroxide decomposition or other chemical mechanisms triggered within the extruder, the process avoids complex mechanical treatment equipment while achieving the desired crosslinking density for extended pipe lifespan.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If photoinitiators and co-agents are used to enable photo-induced crosslinking, then oxidative resistance and mechanical properties are enhanced, but the risk of chemical residual leaching increases

Engineering Contradiction:

Improvemechanical properties and oxidative resistanceVSAvoidchemical residual leaching

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by strategically positioning and dosing photoinitiators and co-agents within the pipe wall structure. By controlling the spatial distribution and concentration gradients of these chemicals, the patent ensures sufficient crosslinking for enhanced mechanical properties and oxidative resistance in critical regions while minimizing residual concentrations that could leach into water, thus resolving the contradiction between strength and harmful factors.

Inventive Principle:

Principle #3Local quality

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 leaching, superior long-term stability, and increased resistance to chlorine, meeting or exceeding NSF 61 and ASTM standards, ensuring safe and durable water transport systems.

Implementation Method 1

a pipe where the pipe comprises a crosslinked polyolefin formed from extruded polyolefin comprising photoinitiator

Methodology Applied

Scientific EffectPhoto-induced crosslinking: Photopolymerisation

Data Source

PatentUS10519286B2Polyolefin pipe

Publication Date: 2019.12.31 UPONOR INNOVATION AB

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. More particularly, this invention relates to the manufacturing of plastic pipes and tubing by utilizing co-rotating twin screw extrusion combined with photo-induced cross-linking, of thermoplastic polymers such as polyethylene, to produce PEX pipes and tubing.