Color Changing Aqueous Coatings High pH Stability
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Solution Overview
Problem
Aqueous color-changing coatings that maintain stability at high pH levels above 10.5 are challenging to develop due to chemical changes and instability during storage, and existing pH-sensitive additives can cause undesirable color changes when incorporated into coatings with lower pH, limiting their use in manufacturing and waste reduction processes.
Innovation Solution
The use of acrylic and styrenated acrylic resins, volatile bases, and specific pH-sensitive color-changing additives like o-cresolphthalein, combined with ether solvents, while avoiding ester solvents, creates a stable color-changing aqueous coating that maintains a high pH for extended storage and undergoes rapid color change upon drying, allowing for reuse of rinse water in subsequent batches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pH-sensitive color-changing additives are incorporated into aqueous coatings with lower pH (7.5-9.5), then color change function is achieved, but undesirable temporary color appears during manufacturing and storage
Solution Approach 1:
The patent changes the pH parameter of the coating formulation to 10.5 or higher, which shifts the equilibrium state of the pH-sensitive color-changing additive to its colored form. This parameter change ensures that the additive remains colored during storage and manufacturing, eliminating undesirable temporary color changes, while still providing the desired color change function when the coating is applied and pH shifts occur.
2Stability of the object's composition
If high pH (above 10.5) is used to maintain color stability of pH-sensitive additives, then color stability is improved, but chemical changes and instability occur during storage
Solution Approach 1:
The patent employs a composite formulation combining pH-sensitive color-changing additives with specific high-pH-compatible resins and additives that collectively provide both color stability and storage reliability. This composite approach allows the system to maintain high pH (10.5 or higher) without suffering from chemical degradation, as the resin and additive combination is specifically selected to be stable under these conditions.
Solution Approach 2:
The patent uses volatile bases that evaporate during storage and application, temporarily maintaining high pH for color stability, then disappearing to allow pH to decrease naturally. This approach allows the system to benefit from high pH stability during storage while avoiding long-term chemical instability issues.
3Loss of substance
If rinse water from previous color changing paint manufacture is reused in subsequent batches with lower pH, then waste reduction is achieved, but color changing additive causes undesirable color in subsequent coatings
Solution Approach 1:
The patent changes the pH parameter of the coating formulation to 10.5 or higher, which ensures that pH-sensitive color-changing additives remain in their colored form at this pH. When rinse water from previous batches is reused, the high pH of the new formulation maintains the additive in its colored state, preventing undesirable color changes in subsequent coatings while enabling waste reduction through rinse water reuse.
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 results in a high-performance, storage-stable color-changing coating that maintains color stability and allows for the reuse of rinse water, reducing waste and manufacturing costs, while avoiding undesirable color changes in subsequent coatings.
Implementation Method 1
it can be seen that the volatile base has evaporated from the coating upon drying
Implementation Method 2
pH sensitive color indicators which impart color at a certain pH and then either become colorless or attain a different color as the coating dries and the pH changes
Data Source
AI summary
This invention relates to color changing aqueous coatings which are stable at a pH greater than about 10.5.