Liquid Aromatic Amine Stabilizers for Polyolefin Pipe Oxidative Resistance
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Solution Overview
Problem
Plastic pipes made from polyethylene, polypropylene, and polybutene-1 used for water distribution are prone to thermo-oxidative degradation when in contact with disinfectants containing oxidative agents, significantly limiting their service life.
Innovation Solution
Incorporating a specific range (0.01 to 0.5 wt.%) of liquid aromatic amines, such as 6-Ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline and dimethylphenylenediamine, into polyolefin moulding compositions to enhance resistance to thermo-oxidative degradation, potentially with additional conventional stabilizers like IRGANOX 1010 or IRGAPHOS 168, without the need for tin compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stabilizer combinations (organotin compounds and NH-containing substances) are used to improve resistance to oxidative disinfectants, then stability against disinfectants is improved, but device complexity and manufacturing complexity increase due to the need for multiple components
Solution Approach 1:
The patent extracts and eliminates the organotin compound component from the stabilizer system, retaining only the aromatic amine (NH-containing substance). This single-component approach maintains effectiveness against oxidative disinfectants while removing the complexity of combining multiple stabilizers, directly resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent changes the chemical composition parameters by selecting specific liquid aromatic amines (such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline and dimethylphenylenediamine) that provide both stabilizing functionality and liquid state at standard conditions. This parameter change enables effective disinfectant resistance without requiring tin compounds, simplifying the overall stabilizer system while maintaining reliability
2Reliability
If solid amino compounds are used as stabilizers, then some stabilizing effect is achieved, but resistance to thermo-oxidative degradation is insufficient compared to liquid aromatic amines
Solution Approach 1:
The patent changes the physical state parameter from solid to liquid for the aromatic amine stabilizer. Liquid aromatic amines provide superior resistance to thermo-oxidative degradation and oxidative disinfectants compared to solid amino compounds, while the liquid state ensures better distribution and effectiveness in the polyolefin matrix during extrusion and service
Solution Approach 2:
The patent creates a composite stabilizer system by combining liquid aromatic amine with the polyolefin matrix, achieving enhanced resistance to both thermo-oxidative degradation and oxidative disinfectants. The specific combination of liquid aromatic amine and polyolefin provides synergistic protection that outperforms conventional solid amino compound stabilizers
3Reliability
If stabilizer amounts are increased to improve resistance to oxidative degradation, then stability is improved, but processability and manufacturing costs may be adversely affected
Solution Approach 1:
The patent optimizes the stabilizer concentration parameter to a specific range (0.01 to 1.0 wt.%, preferably 0.05 to 0.5 wt.%) of liquid aromatic amine in the moulding composition. This optimized concentration provides effective resistance to oxidative degradation and extended service life while maintaining good processability during extrusion, avoiding the adverse effects of excessive stabilizer amounts on manufacturing
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 selected liquid amines significantly improve the stability of pipes against disinfectants' oxidative action, extending their service life by maintaining good processability and achieving an oxidation induction time (OIT) of 10 to 20 minutes at 200°C, outperforming solid amino compounds and prior stabilizer combinations.
Implementation Method 1
resistance to thermo-oxidative degradation of pipes which are in extended contact with liquids which contain disinfectants with an oxidative action
Implementation Method 2
liquid aromatic amines... particularly surprisingly impart good stability to pipes made from the moulding composition against the oxidative action of the disinfectants
Data Source
AI summary
A polyolefinic moulding composition is suitable for producing pipes with improved resistance to thermo- oxidative degradation when these pipes are in extended contact with liquids which contain disinfectants with an oxidative action. Beside thermoplastic polyolefins, the moulding composition additionally contains specific aromatic amines which are liquid under standard conditions as an additive. The invention also relates to a pipe made from the moulding composition and to a process for improving the long-term resistance of water pipework made of plastics to damage by disinfectants with an oxidative action from the water by the use of this moulding composition.