Multimodal Acrylic Latex via Sequential Polymerization
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Solution Overview
Problem
There is a need for a multimodal acrylic-based polymer latex that exhibits desirable performance properties without increased toxicity, as existing methods often rely on acrylamides which pose health and disposal issues, and living ionic polymerization is not viable for predominantly acrylic-based polymers in an emulsion or latex medium.
Innovation Solution
The development of an acrylic latex composition with polymer particles having a multimodal molecular weight distribution, achieved through sequential polymerization in a latex system using a chain transfer agent to control molecular weight, resulting in bimodal or trimodal distributions with distinct higher and lower molecular weight peaks, and the exclusion of hydroxy-functional and conjugated diene monomers to minimize toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If acrylamides are used to improve performance properties, then adhesion and mechanical strength are enhanced, but toxicity increases
Solution Approach 1:
The patent removes acrylamide monomers from the polymer composition entirely, extracting the harmful component while maintaining performance through alternative acrylic-based polymers with multimodal molecular weight distributions
Solution Approach 2:
The patent changes the molecular weight distribution parameters of acrylic polymers from monomodal to multimodal (bimodal or trimodal), creating distinct peaks at different molecular weights to achieve both adhesion (lower MW) and mechanical strength (higher MW) without toxic acrylamides
2Manufacturing precision
If living ionic polymerization is used to control molecular weight, then molecular weight distribution is improved, but the method is not viable for predominantly acrylic-based polymers in emulsion medium
Solution Approach 1:
The patent uses radical polymerization mechanisms with controlled initiation and propagation steps as an intermediary approach that achieves molecular weight control in emulsion medium without requiring living ionic polymerization, making the process viable for acrylic-based polymers
Solution Approach 2:
The patent changes the polymerization mechanism from living ionic to controlled radical polymerization, adjusting reaction conditions and initiator systems to achieve multimodal molecular weight distributions suitable for emulsion polymerization of acrylic monomers
3Reliability
If pre-polymerized seed latex particles are used, then adhesion and durability are improved, but the molecular weight distribution becomes less controlled
Solution Approach 1:
The patent segments the polymerization process into multiple stages with controlled monomer additions, creating distinct molecular weight populations that combine to form a multimodal distribution with both adhesion benefits and controlled characteristics
Solution Approach 2:
The patent performs preliminary controlled polymerization to establish seed particles with specific molecular weight characteristics, then builds upon these seeds in subsequent stages to achieve the final multimodal distribution with controlled properties
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 allows for improved substrate adhesion and physical/mechanical strength while avoiding the toxicity associated with acrylamides, enabling the creation of acrylic latexes with enhanced performance properties suitable for architectural coatings and paint formulations.
Implementation Method 1
adding a polymer molecular weight control agent solution to the reaction vessel... sequentially polymerizing the first set of monomers and the second set of monomers... to form a sequentially polymerized emulsion comprising the multimodal molecular weight distribution
Data Source
AI summary
The present invention relates to polymers polymerized sequentially or in stages and having multimodal molecular weight distributions. The polymers according to the invention can advantageously be present in aqueous emulsion or latex form and can advantageously be used in paint compositions and other coating applications.