Hydrolysis-Stable Polyurethane Coating for Maritime Conduits

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Solution Overview

Problem

Existing polyurethane coatings for offshore oil pipelines face challenges with high thermal stress and limited hydrolysis stability at elevated temperatures, while aromatic isocyanates are brittle and aliphatic isocyanates are toxic and slow-reacting, making them unsuitable for deep-sea applications.

Innovation Solution

A process involving a mixture of aromatic and aliphatic polyisocyanates with polymeric compounds reactive to isocyanates, chain extenders, and catalysts is used to form a polyurethane layer on conduit elements, with a controlled chain extender index to enhance mechanical properties and hydrolysis stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If aromatic isocyanates are used for polyurethane coating, then the coating provides good mechanical properties and thermal stability, but the hydrolysis stability deteriorates at high temperatures

Engineering Contradiction:

Improvemechanical propertiesVSAvoidhydrolysis stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the isocyanate mixture, specifically controlling the ratio of aromatic to aliphatic isocyanates and the chain extender index KV, to achieve both mechanical strength and hydrolysis stability simultaneously

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyurethane system by combining aromatic and aliphatic isocyanates with specific polyols and chain extenders, where each component contributes different properties: aromatic isocyanates provide mechanical strength while aliphatic isocyanates provide hydrolysis stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If aliphatic isocyanates are used for polyurethane coating, then the hydrolysis stability is improved, but the reactivity and processing speed deteriorate

Engineering Contradiction:

Improvehydrolysis stabilityVSAvoidreactivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent adjusts the chain extender index KV parameter and the ratio of aliphatic to aromatic isocyanates to optimize both reactivity and hydrolysis stability, avoiding the need to use purely aliphatic isocyanates which would be too slow-reacting

Inventive Principle:

Principle #35Parameter changes

3Temperature

If polyisocyanurates are used for high temperature stability, then the temperature stability is improved, but the brittleness increases and hydrolysis stability at high temperatures is limited

Engineering Contradiction:

Improvetemperature stabilityVSAvoidbrittleness

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent controls the chain extender index KV and the ratio of aromatic to aliphatic isocyanates to achieve the desired temperature stability without excessive crosslinking that would cause brittleness

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite system combining aromatic and aliphatic isocyanates with specific polyols to achieve temperature stability comparable to polyisocyanurates while maintaining flexibility and improved hydrolysis stability through the aliphatic component

Inventive Principle:

Principle #40Composite materials

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 resulting polyurethane-coated conduit elements exhibit improved hydrolysis stability and mechanical properties, such as tensile strength and elongation at break, while minimizing the use of toxic aliphatic isocyanates and avoiding brittleness, thus meeting the demands of the oil and gas industry in maritime environments.

Implementation Method 1

a mixture of aromatic and aliphatic polyisocyanate is mixed with (b) at least one polymeric compound having at least two hydrogen atoms which are reactive toward isocyanate, (c) chain extenders having a functionality of from 2 to 4 and a hydroxyl number of from 500 to 2500 mg KOH/g

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS10442885B2Hydrolysis-stable polyurethane for coating elements in maritime applications

Publication Date: 2019.10.15 BASF SE

AI summary

A process for producing a polyurethane-coated conduit element includes mixing a) a mixture of aromatic and aliphatic polyisocyanate with, b) at least one polymeric compound having at least two hydrogen atoms which are reactive toward isocyanate, c) at least one chain extender, d) a catalyst, and e) optionally at least one other auxiliary, additive, or both, to form a reaction mixture; applying the reaction mixture to a conduit element; and allowing the reaction mixture to react to form a polyurethane layer. The polyurethane-coating conduit element is suitable for maritime applications in the oil and gas industry, which polyurethane has improved hydrolysis stability at high temperatures and nevertheless satisfies the high mechanical demands in the oil and gas industry.