Microparticulate Titanium Oxide Dispersion for Transparent UV Shielding
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Solution Overview
Problem
Existing microparticulate titanium oxide dispersions in oil mediums struggle to achieve both high transparency and effective UV light shielding, particularly for UVA, due to particle aggregation and poor dispersibility, leading to inadequate UV protection and cosmetic quality issues.
Innovation Solution
A dispersion of microparticulate titanium oxide with specific size ranges (30-100 nm major axis and 8-50 nm minor axis) in a hydrophobic medium using a biterminally-siliconized polyglycerin dispersant, ensuring 10-70% titanium oxide and 1-40% dispersant ratios, enhances stability and UV protection while maintaining transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If microparticulate titanium oxide with size less than 100 nm is used to reduce visible light scattering, then transparency is improved, but UV light scattering ability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size parameters of titanium oxide within specific ranges (major axis 30-100 nm, minor axis 8-50 nm) and the dispersant content (1-40 wt%). This optimization resolves the contradiction by finding the optimal parameter range where particles are small enough to maintain transparency but large enough to scatter UV light effectively, while the controlled dispersant amount prevents aggregation that would compromise UV shielding.
Solution Approach 2:
The patent creates a composite dispersion system combining microparticulate titanium oxide with biterminally-siliconized polyglycerin dispersant in a hydrophobic medium. This composite approach allows the titanium oxide particles to maintain both transparency and UV shielding properties simultaneously, as the dispersant prevents aggregation and maintains optimal particle distribution for dual functionality.
2Object-affected harmful factors
If the amount of microparticulate titanium oxide is increased to improve UV protective effect, then UV protection is improved, but aggregation increases and transparency is lost
Solution Approach 1:
The patent introduces biterminally-siliconized polyglycerin as an intermediary dispersant that mediates between titanium oxide particles. This dispersant adsorbs onto particle surfaces, creating steric barriers that prevent aggregation even at high titanium oxide concentrations (10-70 wt%). The dispersant enables maintaining both high UV protection and transparency by keeping particles individually dispersed rather than aggregated.
Solution Approach 2:
The patent optimizes the dispersant-to-titanium oxide ratio parameter (1-40 wt%) to resolve the contradiction. By controlling this parameter, the system can accommodate high titanium oxide content for UV protection while the sufficient dispersant amount prevents aggregation, thereby maintaining transparency. The parameter optimization allows simultaneous achievement of both goals.
3Illumination intensity
If microparticulate titanium oxide is used to achieve high transparency, then transparency is improved, but particle aggregation increases leading to poor long-term stability
Solution Approach 1:
The biterminally-siliconized polyglycerin acts as a stabilizing intermediary that adsorbs onto titanium oxide particle surfaces. This dispersant creates protective layers around particles, preventing them from aggregating over time. The dispersant's molecular structure provides steric stabilization that maintains particle dispersion stability throughout the product shelf life, ensuring both transparency and long-term stability are maintained.
Solution Approach 2:
The patent controls the dispersant content parameter within 1-40 wt% of titanium oxide amount to ensure adequate surface coverage and steric stabilization. This parameter optimization ensures that particles remain individually dispersed and stable over long periods while maintaining the small size needed for transparency, resolving the contradiction between transparency and stability.
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 provides excellent UV protection in both UVA and UVB regions with long-term stability and transparency, even at lower titanium oxide concentrations, by controlling particle size and using a biterminally-siliconized polyglycerin as a dispersant.
Implementation Method 1
Titanium oxide has electrically a semiconductor structure, and the valence band and the conduction band are not continuous. Therefore, titanium oxide absorbs light of a wavelength that corresponds to the energy higher than the bandgap
Implementation Method 2
titanium oxide absorbs light of a wavelength that corresponds to the energy higher than the bandgap, which is the energy difference between the two levels. Titanium oxide mainly absorbs UV in the UVB region
Implementation Method 3
If the particle size of microparticulate titanium oxide is comparable to the wavelength of light, Mie scattering takes place and the maximum is reached in the vicinity of 1/2 wavelength
Implementation Method 4
If the particle size is smaller than that (less than about 1/10 wavelength), Rayleigh scattering takes place and its scattering ability is inversely proportional to the fourth power of the wavelength
Implementation Method 5
a dispersion of microparticulate titanium oxide with excellent UV protective ability in both UVA and UVB regions, while maintaining a feeling of transparency, and good long-term stability without reaggregation could be obtained by specifying both primary particle size and the size of dispersed particles
Data Source
Figure 1~2
Figure 3
AI summary
The present invention provides a dispersion of microparticulate titanium oxide that can generate a natural finish feeling, which includes a feeling of transparency, and has good long-term stability and an excellent UV protective effect in both UVA and UVB regions. The present invention is a dispersion of microparticulate titanium oxide characterized in that the microparticulate titanium oxide with the average major axis of 30 to 100 nm and the average minor axis of 8 to 50 nm is dispersed, by maintaining the average size of dispersed particles to be 80 to 110 nm, in a hydrophobic dispersion medium. In the dispersion of microparticulate titanium oxide, the content of silicone oil relative to the total hydrophobic dispersion medium is preferably 10 to 100 weight %. Furthermore, it is preferable that the dispersion of microparticulate titanium oxide contains a biterminally-siliconized polyglycerin as a dispersant. The dispersion of microparticulate titanium oxide can be preferably contained in a cosmetic.