Waterborne Phosphorescent Coating pH Buffering
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Solution Overview
Problem
Current phosphorescent water-based coatings using metal aluminate pigments are chemically unstable in water, leading to rapid hydrolysis and destabilization, which reduces their shelf life and performance, and existing stabilization methods increase costs and reduce brightness and afterglow.
Innovation Solution
A water-based phosphorescent coating composition that includes a film-forming latex emulsion, untreated metal aluminate phosphorescent pigment, and a buffer agent to maintain a pH range of 7 to 10, enhancing stability and brightness, with optional dispersants for improved composition stability and application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If metal aluminate phosphorescent pigment is used in water-based coating, then brightness and afterglow performance are improved, but chemical stability deteriorates due to hydrolysis
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the metal aluminate phosphorescent pigment and the water-based coating matrix. The silane coupling agent forms a protective interface layer that prevents direct contact between water and the pigment particles, thereby preventing hydrolysis while maintaining the pigment's phosphorescent properties and brightness.
Solution Approach 2:
The invention creates a composite material system where metal aluminate phosphorescent pigment is combined with silane coupling agent and water-based coating components. This composite structure provides both the desired phosphorescent performance and enhanced chemical stability by integrating multiple functional materials that work together to prevent hydrolysis.
2Illumination intensity
If metal aluminate phosphorescent pigment is used in water-based coating, then brightness and afterglow performance are improved, but shelf life is reduced due to rapid hydrolysis
Solution Approach 1:
The silane coupling agent serves as a protective intermediary that forms a stable interface between the pigment and the water-based coating, preventing water from attacking the pigment particles. This intermediary layer maintains the pigment's integrity over time, thereby extending the shelf life of the coating while preserving its phosphorescent brightness.
Solution Approach 2:
The silane coupling agent is applied beforehand to the metal aluminate phosphorescent pigment particles, creating a protective barrier before the pigment is incorporated into the water-based coating. This pre-protection cushioning prevents hydrolysis from occurring during storage, thereby extending shelf life while maintaining brightness performance.
3Stability of the object's composition
If conventional stabilization methods are used, then chemical stability is improved, but cost increases and brightness is reduced
Solution Approach 1:
The silane coupling agent provides an effective stabilization mechanism that prevents hydrolysis without requiring expensive conventional stabilization methods. The silane forms a thin protective interface layer that maintains chemical stability while being transparent to light, thereby preserving the pigment's brightness and phosphorescent performance without the cost or performance penalties of conventional methods.
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 achieves long-term stability (over six months) and maintains substantial brightness and afterglow performance, making it suitable for various substrates and applications, such as marking building exits and egress pathways, while being cost-effective and environmentally friendly.
Implementation Method 1
a buffer agent to maintain a pH range of 7 to 10
Implementation Method 2
Many alkaline earth aluminate oxides, however, will hydrolyze in the presence of water to form salts
Implementation Method 3
Phosphorescent pigments have long been incorporated into paints and plastics as a means of imparting phosphorescent properties
Data Source
AI summary
Stable, phosphorescent, water-based coating compositions include a latex emulsion, at least one metal aluminate pigment as a source of phosphorescence, and an effective buffering amount of a buffering agent, which may be an organic acid. The ratio of metal aluminum phosphorescent pigment to latex binder in the latex emulsion may be in the range of about 0.5:1 to about 2.0:1. The effective amount of buffering agent may be from about 0.1% to about 10% with respect to emulsion weight. Compositions according to the present invention may have useful shelf lives of six months or longer. Methods of using the phosphorescent latex coatings and coated substrates are also taught.