Preservative-Free Coating Composition with High pH Stability
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Solution Overview
Problem
Existing preservative-free emulsion paints and coatings face challenges with hydrolysis stability, pigment-binding capacity, and storage stability, especially at high pH levels, and often have odor issues and compatibility problems for allergy sufferers.
Innovation Solution
The use of copolymeric polyvinyl ester dispersions derived from vinyl esters of aliphatic saturated carboxylic acids, alpha-olefins, and ethylenically unsaturated silane groups, combined with a strongly basic agent like water-soluble silicate, to create a preservative-free coating composition with high hydrolysis stability and pigment-binding capacity, maintaining pH and thixotropic behavior, and minimizing odor formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If VAE copolymer dispersions are used in preservative-free formulations with high waterglass content, then pigment-binding capacity is improved, but hydrolysis stability and storage stability deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters of the polymer dispersion by using copolymers with specific vinyl ester content (40-95 wt%) and hydrolysis resistance properties. This parameter change allows the system to maintain both high pigment-binding capacity and hydrolysis stability at pH ≥ 10, resolving the contradiction between pigment binding and hydrolysis resistance.
Solution Approach 2:
The invention creates a composite coating formulation combining the specific copolymer dispersion with water-soluble silicates and other additives. This composite approach allows the polymer to provide pigment-binding capacity while the silicate system provides the alkaline environment without compromising hydrolysis stability, thus resolving the contradiction.
2Reliability
If preservatives are added to coating compositions, then storage stability is improved, but compatibility for allergy sufferers deteriorates
Solution Approach 1:
The invention extracts and eliminates preservatives from the coating formulation entirely. By using a high pH water-soluble silicate system (pH ≥ 10) with specific copolymer dispersions, the formulation achieves storage stability without requiring preservatives, thus removing the harmful factor for allergy sufferers while maintaining reliability.
Solution Approach 2:
The coating composition uses the high pH silicate system to provide self-protection against microbial growth and hydrolysis. The alkaline environment created by water-soluble silicates serves as a natural preservative system, eliminating the need for additional preservative chemicals and providing inherent storage stability.
3Ease of manufacture
If high waterglass fraction is used to create preservative-free formulations, then need for preservatives is eliminated, but polymer dispersion hydrolysis stability deteriorates
Solution Approach 1:
The invention changes the pH parameter to be at least 10 using water-soluble silicates, and selects copolymer dispersions with specific hydrolysis resistance properties. This parameter combination allows the formulation to remain preservative-free while maintaining excellent hydrolysis stability, resolving the contradiction between ease of manufacture and reliability.
4Reliability
If styrene/acrylate copolymers are used in high pH formulations, then hydrolysis resistance is improved, but pigment-binding capacity and odor characteristics deteriorate
Solution Approach 1:
The invention changes the polymer chemistry parameters by using copolymers derived from vinyl esters of aliphatic saturated carboxylic acids (C1-C4) with specific composition ratios. This parameter change provides both the required hydrolysis resistance at high pH and improved pigment-binding capacity, resolving the contradiction with styrene/acrylate systems.
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 solution provides a preservative-free coating composition with enhanced hydrolysis stability, high pigment volume concentration, and improved storage stability, while maintaining pH and thixotropic properties, and suppressing odor formation, making it suitable for high pH ranges and allergy-friendly.
Implementation Method 1
the polymer dispersions to be used must, however, be stable to hydrolysis at high pH levels
Implementation Method 2
at least one strongly basic agent to set the pH, in particular at least one water-soluble silicate
Implementation Method 3
coating compositions which have high pigment volume concentrations (PVC) of at least 60% and which possess a high pigment-binding capacity
Data Source
AI summary
A description is given of coating compositions comprising at least one strongly basic agent to set a pH of at least 10, at least one selected vinyl ester copolymer, if desired, pigment and/or filler, and, if desired, further additives customary per se.The coating compositions can be stored without use of additional preservatives and can be used to coat substrates of all kinds.