Acrylic Emulsion Resin Dispersion Stability via Timed Polar Monomer Addition
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Solution Overview
Problem
Existing acrylic emulsion resins face challenges in maintaining excellent adhesion properties and high dispersion stability while avoiding increased viscosity, which hampers their application processability.
Innovation Solution
A process involving the introduction of specific monomers, such as those represented by Chemical Formula 1, during emulsion polymerization, where polar monomers are added after the initiation of the reaction to control surface charge and particle formation, optimizing their distribution and electrostatic repulsive forces for improved stability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the amount of emulsifier is increased to maintain dispersed phase, then particle formation is improved, but particle size decreases and adhesion properties are deteriorated
Solution Approach 1:
The invention changes the chemical composition parameters by introducing polar monomers (acrylic acid, methacrylic acid, or their derivatives) at specific stages of polymerization. This chemical parameter change provides ionic groups that increase electric charge on particle surfaces, enhancing dispersion stability through electrostatic repulsion without relying on excessive emulsifier that would harm adhesion.
Solution Approach 2:
The invention applies preliminary action by introducing polar monomers at specific timing (60-93% of total polymerization time) rather than at the beginning. This timed introduction allows the polymer matrix to form first, then enhances dispersion stability through controlled addition of polar groups, preventing premature particle size reduction and adhesion deterioration.
2Stability of the object's composition
If the amount of polar monomers is increased to provide dispersion stability, then adhesion to polar substrate increases, but particle size decreases and viscosity significantly increases
Solution Approach 1:
The invention applies partial action by introducing polar monomers in controlled amounts at specific polymerization stages rather than in large quantities from the start. This controlled partial introduction provides sufficient dispersion stability through electrostatic repulsion while avoiding excessive viscosity increase that would occur with high concentrations of polar monomers throughout the entire polymerization process.
Solution Approach 2:
The polymer matrix is formed first through preliminary polymerization of non-polar monomers, establishing the base structure with acceptable viscosity. Then polar monomers are introduced in later stages (60-93% of total time) to enhance dispersion stability, ensuring the polar groups are incorporated into an already-formed matrix rather than interfering with initial particle formation and viscosity development.
3Stability of the object's composition
If polar monomers are introduced early in polymerization to increase electric charge, then dispersion stability is improved, but particle size decreases
Solution Approach 1:
The invention performs preliminary polymerization of the main monomer mixture for 60-93% of the total polymerization time before introducing polar monomers. This ensures that the particle framework and size are established first, then polar groups are added to the existing particles to enhance surface charge and dispersion stability without causing significant particle size reduction.
Solution Approach 2:
The polymerization process is segmented into distinct stages: first stage for forming the particle matrix with main monomers, and second stage (at 60-93% of total time) for introducing polar monomers. This segmentation allows each stage to optimize its function - particle formation in the first stage and surface charge enhancement in the second stage - preventing the particle size reduction that would occur if polar monomers were present from the beginning.
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
This approach enhances dispersion stability and adhesion properties while maintaining low viscosity, thereby improving the processability of the acrylic emulsion resin in applications like dispersion and coating.
Implementation Method 1
introducing a monomer mixture comprising (meth)acrylic acid ester-based monomers including C1-14 alkyl groups, and one or more comonomers selected from the group consisting of vinyl ester-based monomers, styrene-based monomers, (meth)acrylic acid-based monomers, and hydroxy group-containing (meth)acrylic ester-based monomers for 2 hours or more, and conducting an emulsion polymerization reaction
Implementation Method 2
R 1 is a functional group including a carbon-carbon unsaturated bond capable of progressing a radical reaction
Implementation Method 3
They provide ionic groups between polymer chains to increase quantity of electric charge on the particle surface, thereby providing dispersion stability by electrostatic repulsive force
Data Source
AI summary
A process for preparing an acrylic emulsion resin is provided by introducing specific monomers at a certain time during an emulsion polymerization process, dispersion stability and adhesion properties of the acrylic emulsion resin are improved, thereby providing an aqueous acrylic pressure-sensitive adhesive that not only has excellent initial adhesion but also has low viscosity and improved processability, and high adhesion holding power.