Aqueous Opacifying Polymer Dispersions for Biocide-Free Microbial Preservation
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Solution Overview
Problem
The need exists for a biocide-free, sustainable, and safer approach to preserve waterborne coatings against microbial contamination, as traditional biocides face regulatory scrutiny and high-pH formulations pose health and safety concerns.
Innovation Solution
Aqueous dispersion of multistage polymer particles with a water-occluded core and polymeric shell, containing specific concentrations of t-C4-C10-alkyl hydroperoxide or hydrogen peroxide and a chelating agent, which are used to inhibit microbial growth without biocides, achieving microbial resistance at a low pH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional biocides (isothiazolinones) are used to preserve waterborne coatings, then microbial growth is inhibited, but health and environmental safety deteriorates
Solution Approach 1:
The patent removes harmful biocides from the system entirely, replacing them with a biocide-free preservation approach using a specific polymer particle composition with water-occluded core and polymeric shell structure, achieving microbial inhibition without toxic additives
Solution Approach 2:
The invention changes the preservation mechanism from chemical biocide action to a physical-chemical system based on polymer particle structure, pH control (7.5-9.5), and controlled oxidation, fundamentally altering how preservation is achieved
2Reliability
If high-pH formulations (pH 10-12.5) are used to preserve paints without biocides, then microbial contamination is prevented, but health and safety concerns increase
Solution Approach 1:
The patent optimizes the pH parameter to a safer range of 7.5-9.5, combining it with specific polymer particle characteristics and controlled oxidation to achieve preservation without the extreme pH conditions that pose health and safety risks
3Reliability
If silver or zinc ions are added to preserve paints, then microbial growth is inhibited, but paint properties are adversely affected and regulatory scrutiny increases
Solution Approach 1:
The invention extracts and removes metal ion preservatives (silver, zinc) from the system, replacing them with an organic polymer-based preservation system that does not adversely affect paint properties or trigger regulatory concerns
4Object-affected harmful factors
If biocide-free preservation methods are developed, then health and environmental safety improves, but alternative preservatives are needed that are currently unavailable
Solution Approach 1:
The patent creates a composite preservation system combining multistage polymer particles with water-occluded core, polymeric shell, controlled pH, and oxidation chemistry, forming a new class of biocide-free preservatives that address both safety and effectiveness requirements
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 composition effectively prevents microbial contamination in opaque polymers, maintaining safety and sustainability without the need for biocides, even after heat aging, and at a pH range that is safer for handling.
Implementation Method 1
b1) from 500 ppm to 5,000 ppm of a t-C4-C10-alkyl hydroperoxide, based on the weight of the composition; or b2) from 1000 ppm to 10000 ppm of hydrogen peroxide
Implementation Method 2
from 50 ppm to 1000 ppm of a chelating agent that is not complexed with a multivalent metal cation
Implementation Method 3
1) a water-occluded core comprising from 20 to 60 weight percent structural units of a salt of a carboxylic acid monomer
Data Source
AI summary
The present invention relates to a composition comprising an aqueous dispersion of multistage polymer particles comprising a water-occluded core and a polymeric shell having a Tg in the range of from 60° C. and 120° C.; a preservative amount of either t-C4-C10-alkyl hydroperoxide or hydrogen peroxide; and less than 1000 ppm of residual monomer. The present invention addresses a need in the art by providing a way to preserve opaque polymers against microbial contamination without the use of a biocide.