Multistage Polymer Dispersion Reducing Coagulum

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional emulsion polymerization processes for aqueous coating compositions produce high coagulum levels when incorporating more than 4.5% ethylenically unsaturated siloxane monomers, which can exceed 2,000 ppm, compromising the stability and performance of coatings, particularly in terms of durability and anti-corrosion properties.

Innovation Solution

A multistage polymer dispersion is developed, comprising a first and second polymer with 4.5% or more structural units of specific ethylenically unsaturated siloxane monomers, where the second monomer composition swells the first polymer before polymerization, reducing coagulum content to less than 2,000 ppm through a controlled two-stage emulsion polymerization process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ethylenically unsaturated siloxane monomers are incorporated into the polymer backbone during emulsion polymerization to improve water repellency and coating performance, then coating performance is improved, but coagulum formation increases significantly

Engineering Contradiction:

Improvecoating performanceVSAvoidcoagulum formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The polymerization process is divided into multiple stages: first forming a base polymer without siloxane monomers, then adding siloxane-containing monomer composition in a second stage. This segmentation prevents coagulum formation by avoiding direct polymerization of high concentrations of siloxane monomers, while still achieving the desired coating performance with 4.5% or more structural units of siloxane monomer in the final multistage polymer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The base polymer is prepared in advance through first-stage polymerization before introducing the siloxane-containing monomer composition. This preliminary action creates a stable polymer matrix that can accommodate the siloxane monomers without causing coagulum, enabling subsequent successful incorporation of hydrophobic monomers.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional emulsion polymerization is used to incorporate siloxane monomers, then coating durability and anti-corrosion properties can be achieved, but coagulum content exceeds acceptable levels

Engineering Contradiction:

Improvecoating durabilityVSAvoidcoagulum content

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The polymerization is conducted in at least two stages: first stage forms a base polymer with conventional monomers, second stage incorporates siloxane-containing monomers. This segmentation enables achievement of coating durability through proper polymer structure while maintaining coagulum content below 2,000 ppm by controlling the sequence and conditions of monomer incorporation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the polymerization parameters by using a multistage approach with specific temperature control, monomer addition sequences, and initiator timing. These parameter changes enable simultaneous achievement of durability (through adequate siloxane content of 4.5% or more) and low coagulum content (less than 2,000 ppm).

Inventive Principle:

Principle #35Parameter changes

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 approach results in a stable aqueous dispersion with improved durability and anti-corrosion properties for coatings, maintaining color and gloss under exposure to elements and providing enhanced corrosion resistance, as demonstrated by reduced coagulum content and improved performance in QUV testing and salt spray resistance.

Implementation Method 1

dispersing in the first polymer, a second monomer composition comprising an ethylenically unsaturated siloxane monomer, whereby the second monomer composition swells the first polymer

Methodology Applied

Scientific EffectSwelling: Absorption (physical)

Implementation Method 2

the coagulum content of the aqueous dispersion is less than 2,000 ppm after filtration through a 44 micron sieve

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS12110394B2Aqueous polymer dispersion and process of making the same

Publication Date: 2024.10.08 DOW GLOBAL TECHNOLOGIES LLC

AI summary

An aqueous dispersion comprising a multistage polymer comprising a first polymer and a second polymer that comprises structural units of an ethylenically unsaturated siloxane monomer, the multistage polymer comprising, by weight based on the weight of the multistage polymer, 4.5% or more of structural units of the ethylenically unsaturated siloxane monomer, and the coagulum content of the aqueous dispersion is less than 2,000 ppm after filtration through a 44 micron sieve.