Cross-Linked Polyolefin Pipe Composition for Low-Leaching Water Service
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Solution Overview
Problem
Existing polyolefin pipes used for drinking water applications face challenges with leaching of additives and crosslinking by-products, which can contaminate the fluid and fail to meet standards for Total Organic Carbon (TOC), taste, and odor tests, requiring additional post-extrusion treatments.
Innovation Solution
The use of a bismaleimido crosslinker in a specific formula, incorporated into a polyolefin structural polymer at a weight percentage of 0.02 to 5%, to form cross-linked polyolefin pipes that minimize leaching and meet or exceed current standards without additional post-extrusion processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional crosslinking methods (peroxide, silane, electron beam) are used, then crosslinked polyethylene pipes achieve good mechanical properties and stability, but chemical residues and additives leach into the fluid, failing TOC, taste, and odor standards
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system by using bismaleimido crosslinkers instead of conventional peroxide or silane systems. This substitution fundamentally alters the crosslinking chemistry to produce minimal chemical residues, thereby reducing leaching while maintaining crosslink density and mechanical properties
Solution Approach 2:
The patent creates a composite material system combining polyolefin structural polymer with bismaleimido crosslinker. This composite approach integrates the crosslinking function directly into the polymer matrix, achieving both the desired mechanical stability and reduced leaching performance through the synergistic interaction between the polymer and crosslinker
2Object-generated harmful factors
If additional post-extrusion heat treatments are applied to reduce leaching, then TOC, taste, and odor standards are met, but manufacturing complexity and production time increase
Solution Approach 1:
The patent performs the crosslinking action during the extrusion process itself rather than as a subsequent post-treatment. The bismaleimido crosslinker is incorporated into the extruded pipe and crosslinking occurs in-line, eliminating the need for separate post-extrusion heat treatment steps while still achieving the required reduction in chemical leaching
Solution Approach 2:
The patent merges the crosslinking process with the extrusion process into a single integrated operation. By combining these two previously separate processes, the patent eliminates additional processing steps, reduces manufacturing complexity, and maintains continuous production flow while achieving the desired reduction in leaching
3Stability of the object's composition
If crosslinking is performed in the melted stage (PEX-a), then homogeneous and uniform crosslinking is achieved with high crosslink density, but peroxide decomposition requires high pressure and temperature conditions
Solution Approach 1:
The patent changes the thermal parameters of the crosslinking process by using bismaleimido crosslinkers that activate at lower temperatures compared to peroxide systems. This allows crosslinking to occur at reduced temperature and pressure conditions while still achieving homogeneous crosslinking, thereby reducing the harsh processing conditions associated with conventional PEX-a methods
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 bismaleimido crosslinker reduces chemical residue leaching, simplifies the manufacturing process, and ensures the pipes meet or exceed standards for TOC, taste, and odor without requiring additional heat treatments, enhancing their performance and compliance.
Implementation Method 1
crosslinking a polyolefin structural polymer by heating the extruded pipe
Data Source
AI summary
This invention relates to a polymeric pipe, and more particularly a polymeric pipe where the pipe comprises a cross-linked polyolefin formed from extruded polyolefin comprising a bismaleimido crosslinker. This invention relates to the manufacturing of plastic pipes and tubing of polyolefinic polymers such as polyethylene, with crosslinking by a bismaleimido crosslinker, to produce crosslinked polyethylene (PEX) pipes and tubing.