Multistage Emulsion Polymer Dispersion for Coating Compatibility

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Solution Overview

Problem

Existing coatings made from polyacrylates and polysiloxanes face challenges in balancing mechanical strength, stability, and water vapor permeability due to poor compatibility between the two materials, leading to suboptimal performance in exterior coatings such as wood, bamboo, and rattan coatings.

Innovation Solution

An aqueous polymer dispersion with a multistage emulsion polymer particle structure, comprising a polysiloxane core, a silane coupling agent transition layer, and a polyacrylate shell, is developed, where the polysiloxane is formed in the first stage, the transition layer in the second stage, and the polyacrylate in the third stage, optimizing the properties of the resulting coatings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polyacrylates and polysiloxanes are simply mixed in water to form composite emulsion, then the preparation process is simple, but the compatibility between the two materials is poor and the mechanical property and stability of the coating are not balanced

Engineering Contradiction:

Improvepreparation process simplicityVSAvoidcoating stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the coating system into distinct functional segments: polysiloxane resin particles providing water vapor permeability and weather resistance, and polyacrylate binder providing mechanical strength and adhesion. These segments are formulated as separate components that are combined in a composition rather than mixed at the molecular level, allowing each to maintain its beneficial properties without compatibility issues

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces compatible solvents and auxiliary agents as intermediaries to facilitate the combination of polysiloxane and polyacrylate. These intermediaries ensure proper dispersion and compatibility between the two materials, enabling them to work together effectively without direct molecular mixing that would cause incompatibility

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If acrylate-siloxane copolymer dispersion is used to improve properties, then mechanical property and weather resistance are improved, but water vapor permeability cannot be well balanced

Engineering Contradiction:

Improvemechanical propertyVSAvoidwater vapor permeability balance

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent assigns different functional qualities to different components: polysiloxane resin particles are specifically responsible for water vapor permeability and weather resistance, while polyacrylate binder handles mechanical strength and adhesion. This localized functional assignment allows each component to optimize its specific property without compromising overall performance balance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite coating composition where polysiloxane resin particles and polyacrylate binder work together synergistically. The composite structure combines the hydrophobic, vapor-permeable nature of polysiloxane with the adhesive, mechanically-strong polyacrylate, achieving a balance of properties that neither material could provide alone

Inventive Principle:

Principle #40Composite materials

3Reliability

If core/shell emulsion with polysiloxane core and polyacrylate shell is prepared, then weather resistance is improved, but the mechanical property and water vapor permeability cannot be well balanced

Engineering Contradiction:

Improveweather resistanceVSAvoidbalance between mechanical property and water vapor permeability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of using a core/shell structure where one material is enclosed by another, the patent inverts the approach by using a composition of separate, dispersed particles. The polysiloxane particles are dispersed within the polyacrylate matrix, allowing both materials to maintain their distinct properties and contribute equally to the overall performance without the constraints of a hierarchical structure

Inventive Principle:

Principle #13The other way round (Inversion)

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 multistage emulsion polymer particle structure effectively balances water vapor permeability and mechanical strength, enhancing the performance of exterior coatings while maintaining moderate preparation conditions, as demonstrated by improved water resistance and mechanical properties compared to traditional coatings.

Implementation Method 1

a transition layer formed in the second stage; wherein the transition layer is made of silane coupling agents

Methodology Applied

Scientific EffectSilane coupling: Chemical Bonding

Implementation Method 2

Aqueous polymer dispersion and preparation method thereof... comprising a multistage emulsion polymer particle

Methodology Applied

Scientific EffectEmulsion polymerization:

Data Source

PatentUS11591432B2Aqueous polymer dispersion and preparation method thereof

Publication Date: 2023.02.28 BASF SE

AI summary

The present invention relates to an aqueous polymer dispersion containing a multistage emulsion polymer particle. The multistage emulsion polymer particle contains a polysiloxane formed in the first stage; a transition layer formed in the second stage; and a polyacrylate formed in the third stage. The transition layer is made of silane coupling agents. The present invention also relates to a method of preparing the aqueous polymer dispersion and use of the aqueous polymer dispersion for preparing coatings.