Polysiloxane-Modified Polyurethane Coatings for Marine Fouling Release
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Solution Overview
Problem
Current fouling release coatings for ship hulls face challenges such as poor adhesion, durability, and high cost, while also being easily damaged due to their low modulus and surface energy, which affects their performance in reducing marine organism settlement and removal.
Innovation Solution
Development of polysiloxane-modified polyurethane coatings with a mixture of polyisocyanate, polyol, and polysiloxane, where the polysiloxane has functional groups capable of reacting with the polyisocyanate, forming a crosslinked structure with a low surface energy top layer and a tough underlayer, enhancing adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If silicone elastomer coatings are used to provide low surface energy and easy fouling release, then fouling organism removal is improved, but adhesion and durability deteriorate
Solution Approach 1:
The coating is segmented into two distinct layers: a top layer containing silicone elastomer particles that provide low surface energy and easy fouling release, and a bottom layer containing polyisocyanate and polyol that forms a crosslinked polyurethane structure providing strong adhesion and durability. This segmentation allows each layer to independently perform its specialized function without compromising the other.
Solution Approach 2:
The invention creates a composite coating system combining silicone elastomer particles with polyurethane matrix. The silicone elastomer particles (typically 10-50 micrometers in diameter) are dispersed within the crosslinked polyurethane structure, forming a composite material that exhibits both the low surface energy properties of silicone and the strong adhesion properties of polyurethane.
2Quantity of substance
If low modulus silicone elastomer coatings are used to achieve low surface energy, then fouling release is improved, but mechanical strength and damage resistance deteriorate
Solution Approach 1:
The coating exhibits local quality differentiation where the top layer contains silicone elastomer particles that provide low surface energy for fouling release, while the bottom layer contains the crosslinked polyurethane matrix that provides mechanical strength and damage resistance. Each region of the coating has locally optimized properties for its specific function.
Solution Approach 2:
The composite structure combines soft silicone elastomer particles with a tough crosslinked polyurethane matrix. The silicone particles protrude from the coating surface to provide low surface energy, while the crosslinked polyurethane backbone provides the mechanical strength and damage resistance that pure silicone coatings lack.
3Reliability
If polysiloxane is reacted with polyisocyanate to form crosslinked structure, then adhesion and durability are improved, but surface energy increases
Solution Approach 1:
The coating is segmented into a crosslinked polyurethane matrix phase and dispersed silicone elastomer particle phase. The crosslinked structure forms in the continuous phase providing adhesion and durability, while the dispersed silicone particles maintain low surface energy at the coating-water interface.
Solution Approach 2:
The crosslinked polyurethane structure is localized to the bottom layer and matrix region where adhesion and durability are needed, while the silicone elastomer particles are localized to the top layer and surface region where low surface energy is needed. This spatial separation of functions prevents the crosslinked structure from increasing overall surface energy.
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 coatings exhibit improved durability, self-stratification, and low surface energy, allowing for easy release of fouling organisms while maintaining adhesion and stability in aquatic environments, reducing fuel consumption and ecological impact.
Implementation Method 1
polysiloxane having functional groups capable of reacting with the polyisocyanate
Implementation Method 2
coatings with low modulus and low surface energy can often provide easy release of fouling organisms
Implementation Method 3
forming a crosslinked structure with a low surface energy top layer and a tough underlayer
Data Source
AI summary
A polymeric material, prepared by reacting a mixture comprising a polyorganosiloxane having one or more isocyanate-reactive functional groups, polyisocyanate, and polyol, is provided. The isocyanate-reactive functional groups, typically one or two, are attached to only a single end of the polyorganosiloxane chains. The polymeric material may be used to form coatings on a substrate and to inhibit fouling on surfaces exposed to aqueous conditions.