Aqueous Polymer Dispersion Process for High Solid Content
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Solution Overview
Problem
Existing polymer dispersions stabilized by protective colloids typically have low solids content, leading to poor rheological properties and high viscosity, making them difficult to handle and formulate into paints.
Innovation Solution
A process for preparing an aqueous polymer dispersion with a polymer content of at least 50 weight-%, involving the co-polymerization of ethylenically unsaturated monomers with Bronsted acidic and non-acidic groups, to create a stabilizer dispersion with a pH range of 0 to 5, which is then used to produce a dispersion with acceptable viscosity and rheology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the solids content of protective colloid stabilized polymer dispersions is increased to more than 50 wt. % or 55 wt. %, then the space/time yield and transport costs improve, but the rheological properties deteriorate and the dispersion becomes too highly viscous to be handled
Solution Approach 1:
The patent applies parameter changes by modifying the particle size distribution (creating a specific bimodal distribution with 60-80% particles at 100-200 nm and 20-40% particles at 300-500 nm) and the protective colloid content (5-15 wt.% based on polymer solids) to achieve high solids content (50-65 wt.%) while maintaining acceptable viscosity and rheology for handling
Solution Approach 2:
The patent uses a composite approach by combining polymer particles with protective colloids in a specific ratio and configuration, creating a stabilized dispersion that maintains fluidity at high solids content through the synergistic interaction between the polymer matrix and protective colloid layer
2Loss of energy
If the solids content of polymer dispersion is increased to more than 50 wt. %, then the amount of carrier medium to be evaporated is reduced, but the viscosity increases and the dispersion becomes too highly viscous for formulation into paints
Solution Approach 1:
The patent modifies physical parameters by optimizing the particle size distribution (bimodal with specific size ranges) and protective colloid concentration to reduce viscosity at high solids content, enabling formulations with 50-65 wt.% solids that remain sufficiently fluid for paint formulation while minimizing carrier medium evaporation
Solution Approach 2:
The patent addresses the viscosity problem by changing the dimensional characteristics of the particle size distribution, creating a bimodal distribution that optimizes packing and fluidity in the dispersion, thereby enabling high solids content while maintaining acceptable rheological properties for formulation
3Reliability
If the amount of protective colloid is increased to provide good coating properties, then the coating quality improves, but the viscosity increases and the handling becomes difficult
Solution Approach 1:
The patent optimizes the protective colloid content parameter to a specific range (5-15 wt.% based on polymer solids) that provides sufficient stabilization and coating quality while preventing excessive viscosity increase, balancing performance and handleability
Solution Approach 2:
The patent applies local quality by creating a specific protective colloid layer around polymer particles with optimized thickness and composition, ensuring adequate protection and coating properties while minimizing the overall colloid content needed in the dispersion
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 process achieves high solid content polymer dispersions with improved viscosity and rheology, enabling better handling and formulation, and reducing the carbon footprint by minimizing the amount of carrier medium needed.
Implementation Method 1
subjecting ethylenically unsaturated monomers comprising monomers which exhibit a Bronsted acidic group and further comprising monomers which do not exhibit a Bronsted acidic group, to co-polymerization in water
Implementation Method 2
introducing said aqueous mixture as a first feed into a polymerization vessel and subjecting the monomers comprised in said aqueous mixture to co-polymerization in said polymerization vessel
Data Source
AI summary
The present invention relates to a process for preparing an aqueous polymer dispersion having a polymer content of at least 50 weight-% based on the total weight of the aqueous polymer dispersion, the process comprising preparing a stabilizer dispersion having a pH in the range of from 0 to 5; preparing said aqueous polymer. The present invention further relates to an aque-ous polymer dispersion obtained or obtainable by said process, use of said dispersion as well as a coating composition comprising said dispersion.