Roofing Articles with Reflective Thin Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional asphalt shingles have low solar heat reflectance, leading to elevated temperatures and increased cooling loads due to high solar absorption, especially with dark-colored granules, which affects their service life and energy consumption.
Innovation Solution
A thin metal or metal oxide film with specific thickness and composition is applied to the roofing articles, providing greater than 60% reflectance in the near infrared range while maintaining transparency in the visible spectrum, thereby enhancing solar heat reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dark-colored granules are used on asphalt shingles, then aesthetic appearance is improved, but solar heat reflectance decreases leading to elevated temperatures
Solution Approach 1:
The patent applies a thin metallic film (5-50 nanometers) that changes the optical properties of the granule surface. This film selectively reflects near-infrared radiation (700-2500 nm) while maintaining visible light transmission, effectively changing the granule's color response to different parts of the electromagnetic spectrum. The metallic coating provides high solar heat reflectance (60-80% in near-infrared range) while preserving the desired aesthetic color appearance.
Solution Approach 2:
The patent creates a composite structure by combining conventional pigment-coated granules with a thin metallic film layer. This composite approach integrates the aesthetic benefits of pigmented granules with the thermal reflective properties of metal films. The granule consists of a mineral core, pigment coating for color, and a thin metallic film (aluminum, zinc, copper, or their alloys) that provides solar heat reflection without compromising the underlying color scheme.
2Illumination intensity
If conventional pigmented coatings are used on granules, then aesthetic color is achieved, but solar radiation reflection is insufficient
Solution Approach 1:
The patent modifies the granule's optical characteristics by adding a thin metallic film that specifically targets near-infrared radiation reflection. This film layer (5-50 nm thick) changes how the granule interacts with solar radiation by reflecting the 700-2500 nm wavelength range while maintaining visible light transmission for aesthetic purposes. The result is enhanced solar radiation reflectance (60-80% in near-infrared) without sacrificing the granule's color appearance.
Solution Approach 2:
The patent changes the physical parameters of the granule surface by applying an ultra-thin metallic film at controlled thickness (5-50 nanometers). This parameter change optimizes the balance between visibility and reflectivity. The film thickness is precisely controlled to ensure sufficient solar heat reflection while maintaining aesthetic appearance and preventing excessive metal accumulation that would alter the granule's color or increase cost.
3Temperature
If white pigment coatings are applied to reduce thermal stress, then solar reflectance is improved, but aesthetic appearance deteriorates
Solution Approach 1:
The patent reverses the conventional approach by applying a thin metallic film that reflects near-infrared radiation while allowing visible light to pass through to the underlying pigmented granule. This creates a color-changing effect where the granule appears aesthetically pleasing in visible light but reflects solar heat effectively in the infrared range. The metallic film thickness (5-50 nm) is optimized to maintain color transparency while providing thermal reflection.
Solution Approach 2:
The patent creates a multi-layer composite structure combining the original pigmented granule with a thin metallic film coating. This composite design allows the pigmented granule to provide aesthetic color in the visible spectrum while the metallic film layer (aluminum, zinc, copper, or alloys) provides solar heat reflection in the near-infrared spectrum. The result is a dual-function granule that satisfies both aesthetic and thermal performance requirements.
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 reduces solar absorption, providing improved thermal stress resistance and maintaining aesthetic appeal by increasing solar heat reflectance while ensuring the desired color and transparency of the roofing articles.
Implementation Method 1
reflect greater than about 60 percent incident radiation having a wavelength between 700 nm and 2500 nm
Implementation Method 2
transmit greater than about 80 percent of incident radiation having a wavelength between 300 nm and 700 nm
Implementation Method 3
The thin film is applied by an application process selected from the group consisting of atmospheric plasma deposition, plasma-assisted polymerization, chemical vapor deposition, physical vapor deposition, sputtering, casting, coating, laminating, electroplating, electroless plating, and thermal spraying
Data Source
AI summary
A roofing article is prepared by applying a thin metal or metal oxide film to a base substrate. The thin film has greater than about 80 percent transmission of incident radiation having a wavelength between 300 nm and 700 nm and greater that about 60 percent reflectance of incident radiation having a wavelength between 700 nm and 2500 nm.