Bio-based Starch Ester Coating for Metal Substrates
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Solution Overview
Problem
Current bio-based coating systems face limitations such as poor adhesion, limited weathering stability, yellowing, and high environmental impact due to synthetic components, especially on metal substrates, and they often require aqueous solvents leading to long drying times and low water resistance.
Innovation Solution
A method using non-ionic starch esters dissolved or dispersed in non-aqueous solvents with specific Hansen solubility parameters, applied to metal, glass, and plastic substrates, which results in a coating with improved adhesion, water resistance, and quick drying properties without the need for crosslinkers or additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aqueous starch ester or ether systems are used, then bio-based content is improved, but drying time increases and water resistance decreases
Solution Approach 1:
The patent changes the solvent parameter from aqueous to non-aqueous (specifically cyclic furans with Hansen solubility parameters δd: 14-19, δP: 2-11, δh: 3-15 MPa1/2). This parameter change resolves the contradiction by enabling faster drying through higher vapor pressure while maintaining water resistance through the hydrophobic nature of the non-aqueous solvent system.
Solution Approach 2:
The patent uses cyclic furan solvents that evaporate completely during drying, leaving no residual solvent that would compromise water resistance. The solvent serves its purpose during application and then disappears, avoiding the problems of water-based systems where the solvent remains and causes prolonged drying and reduced water resistance.
2Strength
If alkyd resin systems are used, then coating adhesion is improved, but environmental impact worsens due to synthetic components and heavy metal driers
Solution Approach 1:
The patent changes the chemical composition parameter from synthetic alkyd resins to bio-based starch esters. This substitution maintains coating adhesion through the inherent bonding capabilities of starch esters while eliminating the environmental harmfulness associated with synthetic components and heavy metal-containing driers.
Solution Approach 2:
The patent replaces persistent synthetic alkyd resins with biodegradable starch ester coatings. The starch ester coating serves its protective function and then naturally degrades, avoiding the long-term environmental persistence and pollution associated with synthetic resin systems and heavy metal driers.
3Reliability
If polyurethane or epoxy systems are used, then coating performance is improved, but bio-based content decreases due to reliance on non-renewable raw materials
Solution Approach 1:
The patent changes the raw material source parameter from non-renewable petroleum-based materials to renewable agricultural starch. This fundamental parameter change enables high bio-based content (over 90% renewable content) while maintaining coating performance through the functional properties of starch ester chemistry.
4Strength
If cellulose-based systems are used, then coating adhesion is improved, but cost increases and yellowing occurs
Solution Approach 1:
The patent changes the carbohydrate source parameter from cellulose to starch. This substitution maintains excellent coating adhesion while avoiding the yellowing problem inherent in cellulose-based systems, particularly cellulose nitrates. The starch ester coating remains stable and does not yellow under UV exposure.
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 method produces a well-adhering, water-resistant coating with excellent barrier properties and adjustable hardness, suitable for corrosion protection on various substrates, using renewable and biobased materials, and avoids the environmental drawbacks of traditional systems.
Implementation Method 1
a solution or dispersion containing or consisting of at least one non-ionic starch ester, dissolved or dispersed in at least one non-aqueous solvent or non-aqueous solvent mixture with Hansen solubility parameters δ d from 14 to 19, δ P from 2 to 11, δ h from 3 to 15 MPa 1/2
Implementation Method 2
a method for producing a well-adhering bio-based coating on a selected substrate
Implementation Method 3
the resulting coating exhibits high moisture and water resistance
Data Source
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AI summary
The present invention relates to a method for producing a well-adherent bio-based coating on a selected substrate using a solution or dispersion of at least one non-ionic starch ester in a non-aqueous solvent with specific solubility parameters. Furthermore, the present invention relates to a coated substrate that can be produced using the method according to the invention. Possible uses of the applied coating are also presented.