Polymer Dispersions via Two-Stage Emulsion Polymerization

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Solution Overview

Problem

Existing polymer dispersion technologies require high amounts of emulsifiers, result in high viscosity, and produce coatings with low water stability, which are not ideal for coating compositions.

Innovation Solution

A two-stage emulsion polymerization process using specific monomers and conditions to produce polymer dispersions with reduced emulsifier usage, lower viscosity, and improved water stability, characterized by controlled particle size and molecular weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If high proportion of emulsifiers (more than 4%) is used in polymerization, then large particles with average particle size of more than 300 nm are produced, but the coating composition requires reduced emulsifier content

Engineering Contradiction:

Improveparticle sizeVSAvoidemulsifier content

Core Design Contradiction:

ShapeVSQuantity of substance

Solution Approach 1:

The patent changes the particle size parameter from large (>300 nm) to small (30-200 nm) by modifying the polymerization process to semi-batch emulsion polymerization with specific monomer feeding rates and using protective colloids instead of traditional emulsifiers, achieving the desired particle size without requiring high emulsifier content

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional emulsifiers with protective colloids that serve as both stabilizers and functional components in the final coating, eliminating the need for separate emulsifier additives and reducing total surfactant content below 4%

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Stability of the object's composition

If high proportion of acrylic acid is polymerized in the first stage, then the polymerization shows high viscosity, but the finished dispersion requires reduced solids content

Engineering Contradiction:

Improvepolymer compositionVSAvoidviscosity

Core Design Contradiction:

Stability of the object's compositionVSForce

Solution Approach 1:

The patent segments the polymerization into semi-batch stages with controlled monomer addition, preventing premature high viscosity by gradually introducing acrylic acid and other monomers at controlled rates, maintaining manageable viscosity throughout the process while achieving the desired composition

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic monomer feeding during semi-batch polymerization, adjusting the rate and sequence of monomer addition based on conversion and viscosity development, allowing the system to adapt and maintain optimal viscosity conditions throughout the polymerization process

Inventive Principle:

Principle #15Dynamics

3Device complexity

If hydroxyalkyl (meth)acrylate is used as protective colloid in situ, then single-stage polymerization is achieved, but the polymerization produces high viscosity requiring reduced solids content

Engineering Contradiction:

Improvepolymerization processVSAvoidviscosity

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The patent changes the polymerization from single-stage to semi-batch with controlled monomer addition, and adjusts the protective colloid concentration and type to maintain lower viscosity while achieving complete polymerization and high solids content in the final dispersion

Inventive Principle:

Principle #35Parameter changes

4Productivity

If traditional emulsion polymerization is used with high emulsifier content, then polymerization proceeds efficiently, but the coating shows low water stability

Engineering Contradiction:

Improvepolymerization efficiencyVSAvoidwater stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent replaces traditional emulsifiers with protective colloids that become part of the polymer structure or adsorb strongly to particle surfaces, providing both polymerization efficiency and long-term water stability without requiring high concentrations of separate emulsifier additives

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates composite particles with cores of non-aqueous polymer and shells containing protective colloids and crosslinked structures, combining the benefits of efficient polymerization with enhanced water stability through the multi-layer composite structure

Inventive Principle:

Principle #40Composite materials

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 results in polymer dispersions with reduced viscosity and enhanced water stability, suitable for coating compositions that provide improved performance and stability in coating applications.

Implementation Method 1

at least two-stage emulsion polymerization

Methodology Applied

Scientific EffectEmulsion polymerization:

Implementation Method 2

followed by a radical polymerization in a subsequent stage

Methodology Applied

Scientific EffectRadical polymerization:

Data Source

PatentEP2513239B1Polymer dispersions

Publication Date: 2013.09.18 BASF SE

AI summary

The present invention relates to coating compounds that contain dispersions of polymers obtained in two stages, to methods for the production thereof, and to the use thereof.