Two-Stage Polymer Dispersion for Low Viscosity Coatings
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Solution Overview
Problem
Existing polymer dispersions for coating compositions require high fractions of emulsifiers, result in high viscosity, and have low water stability, leading to suboptimal performance in coating applications.
Innovation Solution
A two-stage emulsion polymerization process is used to create polymer dispersions with specific monomer compositions and reaction conditions, reducing the need for emulsifiers, lowering viscosity, and enhancing water stability, resulting in coatings with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high fraction of emulsifiers is used in polymerization, then the polymerization can proceed, but the water stability of the resulting polymer is low
Solution Approach 1:
The invention changes the chemical composition parameters by using specific monomer ratios (at least 80 mol% of monomers with formula (I) and at most 20 mol% of monomers with formula (II)), controlling particle size (20-300 nm), and regulating acid number (≤10 mg KOH/g) and hydroxyl number (2-100 mg KOH/g) to achieve high water stability with minimal emulsifier content
Solution Approach 2:
The invention creates a composite polymer structure combining hydrophobic monomers (formula I: alkyl (meth)acrylate, vinylaromatic, hydroxyalkyl (meth)acrylate) and hydrophilic monomers (formula II: carboxylic acid, crosslinker, functional compounds) in specific proportions, forming a core-shell like structure that provides both stability and functionality while reducing emulsifier dependency
2Strength
If a high fraction of hydroxyalkyl (meth)acrylate is used, then the polymer has good adhesion properties, but the viscosity of the dispersion becomes high
Solution Approach 1:
The invention controls the hydroxyl number within 2-100 mg KOH/g and particle size within 20-300 nm to balance adhesion properties and viscosity, ensuring the polymer has sufficient hydroxyl groups for adhesion while maintaining low dispersion viscosity through optimized particle size distribution
Solution Approach 2:
The invention creates local concentration of hydroxyl groups within the polymer structure through specific monomer selection and ratio control, providing adhesion functionality at the polymer-substrate interface while keeping the overall dispersion viscosity low through controlled particle size and composition distribution
3Manufacturing precision
If the particle size is reduced to improve coating properties, then the coating quality improves, but the manufacturing complexity increases
Solution Approach 1:
The invention incorporates particle size control (20-300 nm) as a predetermined parameter in the polymerization process design, using pre-selected monomer combinations and reaction conditions that naturally produce the desired particle size range, thereby achieving high coating quality without complex post-processing or specialized equipment
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 polymer dispersions with reduced viscosity and improved water stability, allowing for the production of high-stability coatings with minimal emulsifier usage, suitable for various coating applications.
Implementation Method 1
free-radical emulsion polymerization of at least one alkyl (meth)acrylate, optionally of at least one vinylaromatic, of at least one hydroxyalkyl (meth)acrylate
Implementation Method 2
emulsion polymerization in a first stage, reaction of (A1) at least one alkyl (meth)acrylate, (B1) optionally at least one vinylaromatic
Data Source
AI summary
The present invention relates to coating compositions which comprise dispersions of polymers obtained by a two-stage procedure, to processes for preparing them, and to their use.