Zirconia Sol Transparency and Concentration via Phase Control
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Solution Overview
Problem
Existing zirconia sols for optical applications lack sufficient transparency and high zirconia particle concentration, and their manufacturing methods often require special equipment and high temperatures, making them costly and inefficient.
Innovation Solution
A zirconia sol with a transmittance of 45% or more at 400 nm and 75% or more at 550 nm, containing 20 wt% or more zirconia particles, an alkali metal oxide in a specific mole ratio, and a monoclinic and tetragonal crystal phase, manufactured through a method involving heating an alkali metal solution, adding zirconium salt in a divided manner, and aging to produce zirconium hydroxide, which is then peptized and purified.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If zirconia particles are dispersed in solvent to create zirconia sol, then the refractive index and mechanical properties of resin are improved, but the transparency of resin decreases
Solution Approach 1:
The patent applies local quality by controlling the crystal structure distribution of zirconia particles. Specifically, it maintains a tetragonal/cubic phase ratio of 20:80 to 80:20, where the tetragonal phase provides mechanical strength while the cubic phase maintains transparency. This local structural control allows different regions of the zirconia sol to contribute differently to mechanical properties and optical properties.
Solution Approach 2:
The patent employs parameter changes by optimizing the average particle size to 1-20 nm and controlling the M2O/ZrO2 mole ratio at 0.02×10^-2 to 0.4×10^-2. These parameter adjustments ensure that the zirconia particles remain small enough to maintain transparency while having sufficient surface area for mechanical reinforcement. The alkali metal oxide addition modifies the crystal structure parameters to achieve the desired phase composition.
2Strength
If zirconia concentration in sol is increased to improve mechanical properties, then the refractive index increases, but transparency decreases
Solution Approach 1:
The patent resolves this contradiction by changing multiple parameters simultaneously: maintaining particle size at 1-20 nm, controlling the tetragonal/cubic phase ratio at 20:80 to 80:20, and limiting M2O/ZrO2 mole ratio to 0.02×10^-2 to 0.4×10^-2. These coordinated parameter changes allow high zirconia concentration (20 wt% or more) to be achieved while maintaining transparency of 45% or more at 400 nm wavelength.
3Quantity of substance
If conventional zirconia sol manufacturing methods are used, then zirconia particles can be produced, but special equipment and high temperature reactions are required
Solution Approach 1:
The patent fundamentally changes the manufacturing parameters from conventional high-temperature firing (500°C or more) to a low-temperature sol-gel process. The key parameter change is conducting the reaction at ambient or mild temperatures using alkali metal oxides (M2O/ZrO2 mole ratio of 0.02×10^-2 to 0.4×10^-2) to control crystal formation. This eliminates the need for special high-temperature equipment and complex dispersion processes.
Solution Approach 2:
The patent uses alkali metal oxides as intermediaries to control the crystal structure formation at low temperatures. The alkali metals (M2O) act as mediators that facilitate the formation of tetragonal and cubic zirconia phases without requiring high-temperature firing. This intermediary approach simplifies the manufacturing process by replacing high-temperature thermal processing with chemical control at milder conditions.
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 resulting zirconia sol maintains high transparency even at high zirconia concentrations, suitable for optical films, and reduces production costs by avoiding special equipment and high-temperature reactions, enhancing refractive index and transparency of resins while maintaining high production efficiency.
Implementation Method 1
a second step of adding 1⁄3 to 2⁄3 of a defined addition amount of a zirconium salt solution to the solution obtained in the first step, a third step of aging the solution obtained in the second step at a predetermined temperature, and a fourth step of adding the remaining portion of the zirconium salt solution used in the second step to the solution obtained in the third step and producing zirconium hydroxide
Implementation Method 2
The resulting zirconia sol maintains high transparency even at high zirconia concentrations
Data Source
AI summary
Provided are a zirconia sol having a transmittance of 45% or more at a wavelength of 400 nm, having a transmittance of 75% or more at a wavelength of 550 nm, and containing zirconia particles in an amount of 20 wt % or more, and a method for manufacturing the zirconia sol.