Large Crystal TiO2 Pigments for Dark Color Solar Reflectance
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Solution Overview
Problem
Current materials struggle to achieve high total solar reflectance in darker or more intense colors, leading to increased air conditioning costs and thermal degradation, while conventional titanium dioxide pigments exhibit high photocatalytic activity, causing premature degradation of sun-exposed items.
Innovation Solution
Development of a composition using large crystal titanium dioxide or doped titanium dioxide particulate materials with specific particle size distributions and coatings, which scatter near-infrared radiation efficiently while minimizing visible light reflection, allowing for darker colors with improved photostability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional titanium dioxide pigments are used to achieve high solar reflectance, then total solar reflectance is improved, but photocatalytic activity increases causing premature degradation
Solution Approach 1:
The patent changes the particle size parameter of titanium dioxide from conventional fine particles to coarse particles with a specific size distribution (D10: 1-10 μm, D50: 10-50 μm, D90: 50-100 μm). This parameter change reduces photocatalytic activity while maintaining high solar reflectance, as the larger particles scatter infrared radiation more effectively without the harmful photocatalytic effects of finer particles.
Solution Approach 2:
The patent creates a composite material system combining coarse titanium dioxide particles with specific coatings (silica, alumina, or zirconia oxides) and non-NIR absorbing colorants. This composite structure maintains the high reflectance properties of TiO2 while the coatings and colorant combinations suppress photocatalytic activity, allowing dark or intense colors to achieve both high solar reflectance and low photocatalytic activity.
2Illumination intensity
If darker or more intense colors are used to meet aesthetic requirements, then color intensity is improved, but total solar reflectance decreases
Solution Approach 1:
The patent changes the particle size parameter of titanium dioxide to coarse sizes (D10: 1-10 μm, D50: 10-50 μm, D90: 50-100 μm), which fundamentally alters the optical properties. These larger particles can scatter infrared radiation effectively even when combined with dark colorants, enabling dark or intense colored products to achieve high total solar reflectance (TSR ≥ 25%) that would be impossible with conventional fine TiO2 particles.
Solution Approach 2:
The patent develops a composite formulation combining coarse TiO2 particles with non-NIR absorbing colorants and oxide coatings. This composite allows the colorant to provide intense coloration while the coarse TiO2 particles maintain high infrared reflectance. The oxide coating on the coarse particles further enhances the ability to achieve both high color intensity and high solar reflectance simultaneously.
3Loss of energy
If multiple coating layers are applied to achieve high solar reflectance and desired color, then solar reflectance is improved, but application complexity and time increase
Solution Approach 1:
The patent merges the functions of solar reflectance enhancement and coloration into a single coating layer. By using coarse TiO2 particles with oxide coatings and non-NIR absorbing colorants combined in one layer, the formulation achieves both high solar reflectance and desired color intensity in a single application, eliminating the need for separate white undercoats and colored overcoats that would otherwise be required.
Solution Approach 2:
The coarse TiO2 particle-based coating serves multiple functions simultaneously: it provides high solar reflectance through infrared scattering, enables dark or intense colors through compatibility with non-NIR absorbing colorants, and reduces photocatalytic activity through its size and coating. This multi-functionality in a single layer simplifies the overall application process while achieving the desired performance.
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 high solar reflectance in a wide range of colors with reduced visible light reflection, lowering air conditioning needs and extending the lifespan of sun-exposed products by minimizing photocatalytic activity.
Implementation Method 1
titanium dioxide or doped titanium dioxide particulate material scatters infrared radiation efficiently in the near infrared (NIR) region of the spectrum
Implementation Method 2
titanium dioxide or doped titanium dioxide particulate material is coated and has ultra-low photocatalytic activity
Data Source
AI summary
A colored composition comprising: a) NIR scattering TiO2 particulate material with an average crystal size of greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm; b) one or more non-white colorant; wherein the particulate material and the non-white colorant are dispersed within a vehicle. This material with a large crystal size has unusually high reflection of NIR radiation and, simultaneously, noticeably diminished reflectance of visible light. Also disclosed is a coated particulate TiO2 material, wherein the material has an average crystal size of greater than 0.40 μm, and the coating comprises one or more oxide material; this provides low levels of photocatalytic activity that were previously unattainable. This coated TiO2 material may be provided in a composition.