Core-shell titanium oxide UV shielding coating
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Solution Overview
Problem
Current UV-shielding coatings with titanium oxide nanoparticles face challenges in achieving weather resistance, transparency, mar resistance, and durable adhesion due to photocatalytic activity, which is difficult to suppress without compromising UV shielding capabilities and aesthetic appearance.
Innovation Solution
A core/shell type tetragonal titanium oxide particle water dispersion is developed, where a nanosized core of tetragonal titanium oxide with tin and manganese in solid solution is coated with a silicon oxide shell, allowing for precise control of shell thickness without pulverizing and sifting steps, and blended with a silicone resin to form a UV-shielding silicone coating composition that achieves weather resistance and UV shielding while maintaining transparency and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If titanium oxide nanoparticles are used for UV shielding, then UV-shielding capability is improved, but photocatalytic activity increases causing poor weather resistance
Solution Approach 1:
A silicon oxide shell is introduced as an intermediary layer between the titanium oxide core and the external environment. This shell acts as a barrier that suppresses the photocatalytic activity of the titanium oxide nanoparticles while allowing the UV-shielding function to remain effective. The shell thickness is controlled to maintain transparency while providing sufficient protection against photocatalysis.
Solution Approach 2:
The invention creates a core/shell composite structure where titanium oxide nanoparticles form the core and silicon oxide forms the shell. This composite structure combines the UV-absorbing properties of titanium oxide with the protective and photocatalysis-suppressing properties of silicon oxide, achieving both UV shielding and weather resistance simultaneously.
2Illumination intensity
If particle size is reduced to 100 nm or less for transparency, then visible light transmittance is improved, but photocatalytic activity increases
Solution Approach 1:
The silicon oxide shell serves as a mediator that suppresses the harmful photocatalytic activity generated by the reduced particle size. By coating the nanoparticle surface, the shell prevents direct interaction between the titanium oxide and environmental substances, thereby reducing photocatalytic degradation while maintaining the transparency benefits of small particle size.
3Reliability
If surface coating with silicon compounds is applied to suppress photocatalytic activity, then weather resistance is improved, but UV-shielding capability and transparency are compromised
Solution Approach 1:
The invention optimizes the shell thickness parameter to achieve the right balance. By controlling the silicon oxide shell thickness to be in the range of 0.1-10 nm, the coating provides sufficient protection against photocatalysis while remaining thin enough to allow UV radiation to pass through to the titanium oxide core for absorption, and thin enough to maintain visible light transparency.
Solution Approach 2:
The silicon oxide shell is applied locally on the surface of each titanium oxide nanoparticle, creating a core/shell structure where different regions have different functions. The core maintains UV-shielding capability while the shell provides weather resistance and photocatalysis suppression, achieving local optimization of properties.
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 effectively suppresses photocatalytic activity, ensuring a coating with enhanced weather resistance, UV shielding, transparency, and durable adhesion, even after exposure to high UV radiation, without detracting from aesthetic appearance.
Implementation Method 1
Titanium oxide is known to have photocatalytic activity. As the particle size of titanium oxide particles becomes smaller, the specific surface area per unit weight increases, and hence, titanium oxide increases its photocatalytic activity.
Implementation Method 2
In particular, a particle size of 100 nm or less is desired for absorbing only the UV band and suppressing visible light from scattering.
Data Source
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AI summary
Core/shell type tetragonal titanium oxide particles consisting of a nanosized core of tetragonal titanium oxide having tin and manganese incorporated in solid solution and a shell of silicon oxide around the core are dispersed in an aqueous dispersing medium. The cores and the core/shell type titanium oxide particles have an average particle size of ≤30 nm and ≤50 nm, respectively. The amount of tin or manganese in solid solution is to provide a molar ratio Ti/Sn or Ti/Mn between 10 and 1,000.