Solar Infrared Reflective Pigments
Cool metal roofs (or rather the colour pre-coated metal) contain a special grade of polyvinylidene fluoride (PVDF) resin typically referred to as Kynar, its original trade name. Kynar is related to Teflon and has become a catchall phrase for the latest versions of PVDF resins, Kynar 500 and Hylar 5000. These coatings are referenced most often in relation to cool roofs because their finishes are durable and soil-resistant, and the reflectance remains constant over the life of the roof.
Combining the PVDF resin with cool infrared reflective pigments improves the product's thermal performance and takes 80 to 85 percent of the heat out of the coating before it has an opportunity to penetrate into the building. This leaves only a small amount in the metal to attack the building, which affects the efficiency of the thermal envelope.
Well, exactly what are Solar Infrared Reflecting Pigments? To answer this we must first examine what Solar Energy is. Solar Energy, or "electromagnetic radiation" from the sun, consists of radiation in the wavelengths from about 250 nanometers (nm) to about 2,500 nanometers.
We can see different colors by selective reflection and absorption of various wavelengths in the visible region. We can perceive a color such as a red car, because the radiation (wavelengths of light) in the red portion of the cars pigment (approximately in the range of 650 nm) is reflected back to our eyes, while the rest of the wavelengths (400 to 650 and above 650) are absorbed by the pigment. We can't see above 700 nm which is the infrared portion of the spectrum, so we really can't determine what is going on there by sight. However, we can feel the effects of this "Infrared Energy", in the form of Heat! Touch your asphalt driveway, your conventional asphalt shingled roof, or your black car which has been out in the sun for a while. It's quite Hot!! In fact some roofing products can reach surface temperatures above 190° F or more. Why is this? It's because these materials absorb a large portion of the infrared (heat) radiation from the sun.
Composition of the Pigments
Just exactly what are these cool pigments and why are they beneficial to industry? These Solar Infrared Pigments are basically synthetic mineral compounds known in the industry as CICP or Complex Inorganic Color Pigments. They are widely accepted as being the best quality pigments available. They are made by reacting mineral compounds together in a calcination process, where these minerals undergo a solid state reaction at temperatures up to 2200° F to make new color compounds. Not all CICP pigments are Solar Reflective however, and only those pigments designated as "Cool" or Reflective, possess the desired properties to reflect the Infrared Solar Radiation desired for today's applications. Most CICP pigments possess extremely good durability and are well suited for exterior applications. They are widely used in coil coating applications, exterior building products and roofing. These new products are now in great demand and are replacing the currently used CICP products.
Ultra Violet - The wavelengths less than 400 nm are referred to as the
"Ultraviolet" (UV) region. The UV region contains the shorter wavelengths of radiation that can cause damage to our bodies and also causes much of the photo degradation to paints and polymers.
Visible Light - The range of wavelengths between 400 nm to 700 nm is called the visible region. This region is the area where our eyes are attuned to see light in all its various colors and shades.
Infrared - The final area from 700 nm to about 2500 nm is called the "Infrared" region. These longer infrared wavelengths are invisible to the naked eye, yet contain over half of the solar energy which strikes the earth.
Copyright 2008 Colourcoil Industries Sdn. Bhd. All rights reserved.