Stabilizing Silver-Titanium Oxide Sol with Copper and Quaternary Ammonium
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Solution Overview
Problem
Photocatalytic titanium oxide sols containing silver suffer from discoloration and precipitation when exposed to light, leading to reduced functionality and commercial value, especially when used in dark environments where continuous UV irradiation is not possible, and existing methods to stabilize them are inefficient.
Innovation Solution
A photocatalytic titanium oxide sol is developed that includes silver, copper, and a quaternary ammonium hydroxide, with specific ratios and forms to prevent discoloration and precipitation, maintaining stability and antibacterial effectiveness even in dark conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver is added to titanium oxide sol to provide antibacterial properties, then antibacterial efficacy is improved, but discoloration and precipitation occur when exposed to light
Solution Approach 1:
A chelating agent is introduced as an intermediary substance that binds to silver ions, preventing their direct interaction with titanium oxide and subsequent reduction. This mediator maintains silver in a stable, dispersed state within the sol, eliminating discoloration and precipitation while preserving antibacterial properties.
Solution Approach 2:
The invention creates a composite system combining titanium oxide, silver, and chelating agents in specific ratios. This composite structure allows the components to work synergistically, where the chelating agent protects silver from reduction by titanium oxide while maintaining the photocatalytic activity of titanium oxide and antibacterial properties of silver.
2Adaptability or versatility
If silver is added to provide antibacterial properties in dark environments, then dark-place antibacterial function is improved, but the sol becomes unstable and discolors
Solution Approach 1:
The chelating agent serves as a protective intermediary that stabilizes silver ions in the absence of light, preventing the harmful discoloration effect while enabling the beneficial dark-place antibacterial function. This allows the sol to maintain both versatility and aesthetic properties.
3Reliability
If multiple application steps are used to stabilize silver on photocatalytic film, then antibacterial stability is improved, but production complexity increases
Solution Approach 1:
The invention merges the stabilization function into the sol formulation itself by incorporating chelating agents during sol preparation. This combines multiple functions (antibacterial activity, stability, and dispersion) into a single homogeneous solution, eliminating the need for separate application and stabilization steps.
Solution Approach 2:
The chelating agent is added during sol preparation, performing the stabilization action in advance before the sol is applied. This preliminary action prevents discoloration and precipitation from occurring during subsequent storage and application, simplifying the overall production process.
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 sol exhibits minimal discoloration and gelation, maintaining high antibacterial efficacy both in dark environments and under UV sterilization, with improved storage stability and operational efficiency.
Implementation Method 1
titanium oxide has a photocatalytic effect that it presents oxidoreductive functions to decompose harmful matters and to show antibacterial properties when irradiated with ultraviolet rays
Implementation Method 2
An inorganic antibacterial component includes a metal such as silver, copper and zinc... possess the photocatalyst effect and the antibacterial properties due to metal ions
Data Source
AI summary
The object of the present invention is to provide a photocatalytic titanium oxide sol which presents antibacterial properties in a dark place, and, in particular, relates to a photocatalytic titanium oxide sol which is stable and causes no discoloration by light even though containing silver, and relates to a coating composition and a member using the same. The photocatalytic titanium oxide sol according to the present invention is characterized by including silver, copper and a quaternary ammonium hydroxide. The photocatalytic coating composition has the photocatalytic titanium oxide sol dispersed in a binder. Furthermore, the member includes coating the surface of a substrate with the photocatalytic coating composition. The photocatalyst titanium oxide sol according to the present invention can contain highly antibacterial silver by skillfully utilizing copper and a quaternary ammonium hydroxide, and accordingly can show an antibacterial effect not only in a dark place simply due to silver, but also a higher antibacterial effect in a conventional application of employing ultraviolet sterilization by concomitantly using the photocatalyst titanium oxide sol according to the present invention and an ultraviolet sterilizer.