Paint knowledge | coating process to keep the roof cool

Core tip: environmental friendly and green architectural design is becoming increasingly popular in North America However, there are many different ways of doing green design One of the most attractive designs for the benefit of homeowners is the use of cool roof technology, which reduces the cost of air conditioning in buildings by reducing the temperature of the roof Through the research of many national laboratories and other scientific research institutions, it shows that paying attention to cool roof technology is an effective way to achieve national energy saving, which can reduce the energy demand of buildings and residential areas Many cities in the United States are developing cool roof technology, introducing the need for cool roofs into their building codes, or working with large companies Shenyang steel structure fireproof coating construction expert punde Building Fire Engineering Co., Ltd Recommended introduction: since its establishment, Shenyang punde Construction Fire Engineering Co., Ltd has cultivated a group of professional construction teams with excellent equipment, rich experience and serious responsibility with advanced and scientific management methods and strict engineering quality assurance and after-sales service system It has undertaken a number of fire system installation projects, which has been praised by customers Every idea and special requirement of you will be fully considered by us and fully realized in the construction technology, which will become the cornerstone of our successful long-term development We are looking forward to your invitation, to provide you with quality services and high-quality technical support! All construction coatings have passed ISO9001 Paint Home News: environmental friendly and green architectural design is becoming increasingly popular in North America However, there are many different ways of doing green design One of the most attractive designs for the benefit of homeowners is the use of cool roof technology, which reduces the cost of air conditioning in buildings by reducing the temperature of the roof Through the research of many national laboratories and other scientific research institutions, it shows that paying attention to cool roof technology is an effective way to achieve national energy saving, which can reduce the energy demand of buildings and residential areas Many cities in the United States are developing cool roof technology, introducing the need for cool roofs into their building codes, or working with large companies on cool roof projects As a result, the concept of cool roofs has also been adopted by national green building advocacy organizations and industrial projects, such as the energy saving Star project of the environmental protection agency and the cold metal roof alliance Therefore, the concept of cool roof is a hot topic in the construction industry and coating industry PVDF (polyvinylidene fluoride) coating has been tested in Florida for decades, showing excellent performance, including optimizing cool roof technology by maintaining TSR value of the coating Most traditional roof materials absorb a certain amount of solar radiation, which causes the surface temperature to rise This energy not only reaches the house, but also accelerates the aging of roof materials The long-term effective cool roof scheme must consider the following two problems: it must be able to effectively reduce the temperature of the roof surface in hot weather, and it can maintain the performance in a long service life without additional maintenance PVDF resin is the most weather resistant coating for metal roof and other building surfaces The ultra UV and chemical resistance of this kind of coating make it have excellent luster and color stability, as well as excellent anti pulverization performance The first fluorocarbon coating resin for building was commercialized in 1965 Since then, thousands of buildings in the world have been coated with this fluorocarbon coating by roll coating or spray coating process Since the 1960s, this fluorocarbon coating test sample has been exposed in the South Florida exposure test center for nearly 40 years, and still keeps the original color Most of the commercial PVDF coatings are non-aqueous and need to be baked at high temperature for a short time Therefore, the typical application of PVDF coating is to apply on metal substrate, such as metal coil or aluminum plate In order to obtain super weather resistant practical coatings, PVDF coatings usually use the most durable inorganic pigments and a small amount of monomer acrylic resin, such as methacrylic resin, ethyl acrylic resin Acrylic resin is used to improve some properties of coatings, such as pigment dispersion and coating adhesion, while pure PVDF does not have these properties because of its chemical inertia Due to the compatibility of the acrylic resin and PVDF, the interface is actually a network interpenetrating alloy structure after baking Because this network interpenetrating structure is thermoplastic and thermodynamically stable, and the main substrate is photochemical inert PVDF, PVDF resin coating still has strong protection after decades, even in high temperature roof environment The traditional cross-linked network resin, such as polyester, can reach 80 ° C or higher in the sun, humidity and high temperature environment, especially in the hot weather These factors accelerate the degradation of cross-linked network resin, resulting in the degradation of coating luster, pulverization and even the failure of coating performance The amount of heat accumulated on the building surface by total solar reflection and cool roof technology is mainly determined by two physical properties: long wave thermal radiation and reflectivity Thermal radiation is the ability to measure the radiant heat of a hot object Generally, the thermal radiation of metal is low, while that of polymer coating is high, including PVDF coating Reflectivity refers to the ratio that heat is reflected and scattered but not absorbed Reflectivity depends on many factors, which are affected by coating formula and construction method A common calculation method of solar reflectance is all solar reflectance, or tsr6 Generally speaking, TSR refers to the ratio of sunlight reflected by the coating TSR determines the energy contained in the solar spectrum, including the energy in the near-infrared region where half of the solar radiation energy is stored In general, the higher the TSR, the more conducive to the generation of cool roofs The influence of pigment on the performance of cool roof is as mentioned above, and the choice of pigment has a great influence on the TSR value of roof coating However, it is obvious that the TSR values of different black pigments are also very different This difference is caused by the different reflectance of pigments in the infrared region After observation, it was found that there were similar TSR differences in other colors For each color system, the pigment with the highest TSR value is the most suitable paint for cool roofs Of course, it has been proved that the pigment itself should be fully weather resistant For this reason, almost all high-quality roof coatings use the most durable inorganic pigments This formula ensures the long-term stability of paint color as long as that of paint resin Because the black paint absorbs too much solar energy in the visible region, the use of pigments with high TSR value can make it have significant benefits in heat reduction For the black pigment coating with high TSR, the temperature rise is only a little higher than that of the white coating On the contrary, for the black coating with low TSR value, the temperature in the infrared box increases to 70 ° C, close to the heat of boiling water TSR values of a series of waterborne PVDF coatings with different colors were also studied The test samples have been exposed in Florida for five to six years The reflection value of these samples without cleaning is reduced by about 3% If they are cleaned slightly, the reduction of reflection value is less than 3% At the same time, these samples still maintain a good color and luster Based on these test data, a variety of light and dark water-based PVDF coatings can meet the performance requirements of different places for cool roof coatings, including the retention value of TSR Zheng Min paint home is specialized in coating, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration 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