Composite Layer Structure for Subsea Insulation Adhesion
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Solution Overview
Problem
Subsea pipelines and structures face challenges due to temperature and pressure changes, leading to viscosity issues and clogging from hydrates and waxes, and existing insulation materials like polyethylene and polypropylene have poor adhesion properties, resulting in integrity and flow problems during petroleum fuel transport.
Innovation Solution
A composite article with a low surface energy polymer, a poly(meth)acrylate layer, an epoxide layer, and a hydrolytically resistant polyurethane elastomer layer, formed from an aliphatic isocyanate and hydroxyl-functional polymer, providing improved adhesion and maintaining tensile strength even after submersion in seawater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyethylene or polypropylene insulation is used on subsea structures, then insulation performance is achieved, but adhesion to patches is poor resulting in integrity problems
Solution Approach 1:
The coating system is divided into multiple functional layers: a low surface energy polymer layer (polyethylene or polypropylene) providing insulation and resistance to seawater, and a separate poly(meth)acrylate layer providing adhesion to patches. This segmentation allows each layer to optimize its specific function without compromise.
Solution Approach 2:
The poly(meth)acrylate layer acts as an intermediary between the low surface energy polymer insulation layer and the metal patch. It adheres to both surfaces, creating a reliable bond that would be impossible with the low surface energy polymer alone.
2Reliability
If existing elastomers are used in subsea pipelines, then insulation and flow maintenance are achieved, but they degrade under temperature and pressure changes
Solution Approach 1:
The patent modifies the chemical composition of the elastomer by incorporating specific ratios of polyether polyol (30-70 wt%) and polyester polyol (70-30 wt%), along with controlled molecular weight and hydroxyl functionality. These parameter changes enable the elastomer to withstand the extreme temperature and pressure variations in subsea environments while maintaining flexibility and adhesion.
Solution Approach 2:
The elastomer is formulated as a composite material combining polyether and polyester polyols with specific additives and curing agents. This composite structure provides both the thermal stability needed for subsea conditions and the adhesion properties required for bonding to metal surfaces.
3Strength
If flame treatment is applied to polyethylene to increase surface energy, then adhesion ability improves, but peel strength remains poor
Solution Approach 1:
The poly(meth)acrylate layer serves as an intermediary that adheres to both the flame-treated polyethylene surface and the metal patch. This intermediate layer provides the necessary adhesion mechanism that flame treatment alone cannot achieve, creating a reliable bond system.
Solution Approach 2:
The adhesion function is separated from the insulation function by using distinct layers. The flame-treated polyethylene provides insulation and base adhesion, while the poly(meth)acrylate layer provides the primary adhesion bond to the patch, ensuring high peel strength.
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 composite article achieves enhanced peel strength and retains over 90% of its initial tensile strength after 24 weeks in seawater, ensuring the integrity and flow of petroleum fuels through subsea structures.
Implementation Method 1
the hydrolytically resistant polyurethane elastomer layer is formed as the reaction product of an aliphatic isocyanate component and an isocyanate-reactive component
Implementation Method 2
A composite article with a low surface energy polymer, a poly(meth)acrylate layer, an epoxide layer, and a hydrolytically resistant polyurethane elastomer layer, formed from an aliphatic isocyanate and hydroxyl-functional polymer, providing improved adhesion
Data Source
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AI summary
A composite article is formed by disposing a poly(meth)acrylate layer, formed as the reaction product of at least one acrylate that is polymerized in the presence of an organoborane initiator, on and in direct contact with a low surface energy polymer layer, disposing an epoxide layer on and in direct contact with said poly(meth)acrylate layer, and disposing a hydrolytically resistant layer on and in direct contact with said epoxide layer. The hydrolytically resistant layer is a hydrolytically resistant polyurethane elastomer that is the reaction product of an aliphatic isocyanate component and an isocyanate-reactive component that retains at least 90 % of its initial tensile strength after submersion in standardized seawater for 24 weeks. The isocyanate-reactive component is a hydroxyl- functional polymer having an average hydroxy functionality ranging from 2 to 3, wherein the hydroxyl-functional polymer is a dimer diol, a trimer triol, or a combination thereof.