Aqueous Alkyd Binder Composition for High-Solid Coatings
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Solution Overview
Problem
Aqueous coating compositions with dispersed binder polymers typically have low binder polymer content due to viscosity limitations, requiring multiple layers for an acceptable coating and high energy for drying, while existing high solid content compositions lack stability and optimal viscosity for good appearance and weather resistance.
Innovation Solution
A process combining a low viscosity liquid alkyd with an aqueous dispersion of another alkyd, emulsifying the first alkyd to create a stable aqueous binder composition with emulsified droplets and dispersed particles in a single phase, achieving a high alkyd content and suitable viscosity for coatings with improved appearance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If binder polymer content is increased above 40 wt%, then coating performance and layer thickness improve, but viscosity increases making the composition unstable and difficult to process
Solution Approach 1:
The binder polymer is segmented into two distinct forms: emulsified binder polymer droplets (1-20 μm) and dispersed binder polymer particles (50-500 nm). This segmentation allows the composition to achieve high total binder content (60-85 wt%) while maintaining stability, as each phase contributes differently to the overall properties - emulsified droplets provide film formation and dispersed particles provide stability and rheological control.
Solution Approach 2:
The invention changes the physical state and size parameters of the binder polymer by creating a dual-phase system with specifically controlled droplet sizes (1-20 μm for emulsified, 50-500 nm for dispersed). This parameter control allows high binder content while maintaining low enough viscosity for stability and processing.
2Productivity
If binder polymer content is increased, then fewer coating layers are needed, but energy consumption for drying increases
Solution Approach 1:
By optimizing the binder polymer content to 60-85 wt% through the dual-phase system, the invention reduces the number of coating layers needed to achieve acceptable coverage and performance. This directly reduces the total energy consumption for drying, as fewer layers require less cumulative drying energy despite the higher solids content per layer.
3Productivity
If high solid content binder compositions are prepared, then fewer layers are needed, but appearance properties such as gloss and image clarity deteriorate
Solution Approach 1:
The segmented binder polymer system with emulsified droplets (1-20 μm) and dispersed particles (50-500 nm) provides different functional benefits: the emulsified droplets facilitate film formation and the dispersed particles ensure stability and smooth film surface. This segmentation enables high binder content (60-85 wt%) while maintaining excellent appearance properties including gloss and image clarity, as the fine dispersed particles create a smooth film surface.
4Productivity
If high solid content binder compositions are prepared, then fewer layers are needed, but weather resistance deteriorates
Solution Approach 1:
The dual-phase binder polymer system with emulsified droplets and dispersed particles creates a synergistic effect where the emulsified phase provides flexible film formation and the dispersed phase provides structural stability. This segmentation enables the composition to achieve high binder content (60-85 wt%) while maintaining excellent weather resistance, as both phases contribute to forming a durable, crack-resistant coating film.
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 aqueous binder composition provides coatings with high alkyd content, good gloss, and excellent durability, even after a limited number of layers, with enhanced stability and weather resistance.
Implementation Method 1
combining a liquid first alkyd having a relatively low viscosity with an aqueous dispersion of a second alkyd. The thus-obtained binder composition comprises emulsified first alkyd and dispersed second alkyd in a single aqueous phase
Data Source
AI summary
The invention relates to a process for the preparation of an aqueous binder composition comprising the following steps: a) providing a first alkyd as a homogenous liquid, the liquid comprising at least 90 wt% of dissolved or molten first alkyd and the liquid having a viscosity in the range of from 0.5 to 5.0 Pa.s determined according to ISO 3219 at 23 °C and at a shear rate of 100 s-1; b) providing an aqueous dispersion of a second alkyd; and c) emulsifying the first alkyd provided in step a) by adding the liquid provided in step a) to the aqueous dispersion provided in step b) or by adding the aqueous dispersion provided in step b) to the liquid provided in step a) and agitating to obtain the aqueous binder composition, wherein the aqueous binder composition comprises emulsified first alkyd and dispersed second alkyd in a single aqueous phase, and the first alkyd is emulsified in droplets having a volume mean diameter in the range of from 1 to 20 μm. The invention further relates to an aqueous binder composition obtainable by such process and to an aqueous coating composition comprising such binder composition.