Viscous Polyamide Composition for Stable Extrusion at High Temperature
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Solution Overview
Problem
Current polyamide compositions used in flexible pipes for offshore oil and gas applications exhibit rapid aging and limited thermal resistance, requiring high-cost elastomers and phosphoric catalysis, which affects melt viscosity stability and working temperature.
Innovation Solution
A composition combining a catalyst, a copper-based heat stabilizer, and an oligo- or polycarbodiimide with a thermoplastic polymer matrix, specifically designed to achieve stable melt viscosity and resistance to thermal oxidation, allowing for higher working temperatures and prolonged pipe lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If phosphoric catalysis is used to increase melt viscosity, then the composition becomes too fluid and unstable during transformation, but without it the viscosity is insufficient for extrusion
Solution Approach 1:
The patent changes the chemical parameters of the catalytic system by replacing phosphoric acid with a specific combination of carboxylic acid catalyst and copper-based heat stabilizer. This parameter change maintains sufficient melt viscosity for extrusion while preventing excessive fluidity and viscosity instability during the transformation process, particularly at temperatures above 200°C.
Solution Approach 2:
The invention uses a composite catalytic system combining carboxylic acid catalyst with copper-based heat stabilizer (such as copper iodide, copper bromide, or copper chloride). This composite approach provides both the catalytic activity needed for extrusion and the thermal stability required to maintain consistent melt viscosity throughout the processing period.
2Reliability
If polyamide is used for temperatures above 40°C, then cost is reduced compared to PVDF, but thermal resistance and aging resistance are insufficient for high-temperature offshore applications
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing copper-based heat stabilizers and specific carboxylic acid catalysts into the polyamide matrix. These compositional changes enable the polyamide to maintain its mechanical properties and resistance to aging at temperatures up to 100°C, effectively raising the working temperature limit without switching to more expensive polymers like PVDF.
Solution Approach 2:
The copper-based heat stabilizer acts as an intermediary substance that protects the polyamide chains from thermal degradation and oxidation. This mediator allows the polyamide to operate at higher temperatures by intercepting and neutralizing harmful thermal effects, thereby extending the service life and reliability of the flexible pipe in high-temperature offshore environments.
3Reliability
If H-NBR elastomer is used to improve resistance to aging, then aging resistance increases, but cost increases and additional grinding process is required
Solution Approach 1:
The invention extracts and removes the H-NBR elastomer component from the formulation, replacing it with a chemical stabilization system based on copper-based heat stabilizers and carboxylic acid catalysts. This elimination simplifies the material composition and processing requirements while maintaining or improving resistance to aging through chemical protection mechanisms rather than elastomeric reinforcement.
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 composition maintains stable melt viscosity and enhanced thermal resistance, enabling flexible pipes to operate effectively at higher temperatures for extended periods without significant viscosity changes, thus improving mechanical and chemical resistance.
Implementation Method 1
at least one catalyst... with a matrix comprising at least one thermoplastic polymer... to form a viscous composition
Implementation Method 2
at least one copper-based heat stabilizer... resistance to thermal oxidation
Data Source
AI summary
The invention relates to the use of at least one catalyst, at least one copper heat stabiliser and at least one oligo- or poly-carbodiimide with a matrix including at least one polyamide, in order to form a composition that has a good melt viscosity and is stable during transformation, in particular during extrusion.