UV Reflective Aluminum Foil With Ultra-Smooth Low-Defect Surface
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Solution Overview
Problem
Conventional aluminum foils exhibit insufficient reflectance for ultraviolet light in the 250 nm to 400 nm range, particularly in the deep ultraviolet range of 254 nm to 265 nm, which hampers their effectiveness in ultraviolet sterilization applications.
Innovation Solution
The development of an aluminum foil with controlled surface roughness, limited aluminum particle and crystallized product coverage, and a protective layer to enhance reflectance, featuring a surface roughness Ra of less than 20 nm, a total surface area of aluminum particles less than 0.05%, and a crystallized product surface area less than 2%, along with a protective layer providing greater than 80% reflectance in the deep ultraviolet range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional aluminum foil is used, then it provides basic ultraviolet light reflection, but the reflectance is insufficient (less than 85% in 250-400 nm range and less than 80% in 254-265 nm range)
Solution Approach 1:
The patent applies parameter changes by precisely controlling surface roughness (Ra ≤ 20 nm) and the area ratios of aluminum particles (≤ 0.05%) and crystallized products (≤ 2%). By optimizing these physical parameters, the reflectance is improved to ≥ 85% in the 250-400 nm range and ≥ 80% in the 254-265 nm range, resolving the contradiction between basic reflection and sufficient light condensing effect.
Solution Approach 2:
The patent employs composite materials by combining aluminum foil with a protective layer containing fluororesin. This composite structure not only protects the aluminum foil surface but also enhances the overall reflectance properties, achieving the required ≥ 85% reflectance in the ultraviolet range while maintaining durability and light condensing effectiveness.
2Illumination intensity
If surface roughness is increased to improve light scattering, then light distribution may improve, but reflectance decreases
Solution Approach 1:
The patent applies parameter changes by setting the surface roughness parameter Ra to be ≤ 20 nm, which is a very smooth surface. This controlled roughness parameter prevents excessive light scattering while maintaining high reflectance (≥ 85% in 250-400 nm range), effectively resolving the contradiction between light scattering and reflectance.
3Illumination intensity
If aluminum particles and crystallized products are present on the surface, then surface coverage increases, but reflectance decreases
Solution Approach 1:
The patent applies parameter changes by controlling the area ratio of aluminum particles to be ≤ 0.05% and crystallized products to be ≤ 2%. By maintaining these low coverage parameters, the surface remains highly reflective (≥ 85% in 250-400 nm range) while allowing minimal presence of particles and crystallized products, thus resolving the contradiction between surface coverage and reflectance.
Solution Approach 2:
The patent applies local quality by ensuring that the regions with aluminum particles and crystallized products are highly localized and minimal in area. This localized control allows the majority of the surface to maintain high reflectance properties while accommodating necessary surface features, effectively resolving the contradiction between surface coverage and overall reflectance.
4Illumination intensity
If no protective layer is applied, then the aluminum foil surface remains simple and cost-effective, but durability and reflectance are compromised
Solution Approach 1:
The patent applies composite materials by adding a protective layer containing fluororesin to the aluminum foil. This composite structure enhances both durability and reflectance (maintaining ≥ 85% in 250-400 nm range) while the protective layer also protects the underlying aluminum surface. The added complexity is justified by the significant improvement in performance and longevity.
Solution Approach 2:
The patent applies the intermediary principle by introducing a protective layer as a mediator between the aluminum foil and the external environment. This protective layer serves multiple functions: protecting the aluminum surface from degradation, maintaining high reflectance (≥ 85% in 250-400 nm range), and providing additional durability. The intermediary layer resolves the contradiction between simplicity and performance by adding a functional element that enhances overall system effectiveness.
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 aluminum foil achieves high reflectance of over 85% in the 250 nm to 400 nm range and greater than 80% in the 254 nm to 265 nm range, significantly improving ultraviolet light condensing and sterilization efficacy.
Implementation Method 1
Aluminum (Al) is an only material having a high reflectance to the ultraviolet light in a wavelength range of 250 nm to 400 nm
Implementation Method 2
A total reflectance of a surface of the protective layer to deep ultraviolet light in a wavelength range of 254 nm to 265 nm inclusive is greater than or equal to 80%
Data Source
AI summary
Discussed is an aluminum foil for ultraviolet light reflecting materials, wherein a ratio of a total surface area of aluminum particles pressed into or adhering to a region having a predetermined surface area to the surface area of the region is less than or equal to 0.05%, the total surface area of crystallized products present in the region having a predetermined surface area is less than or equal to 2% with respect to the surface area of the region, an average surface area per crystallized product is less than or equal to 2 μm2, and arithmetic surface roughness Ra of the region is less than 20 nm.