Polyurethane cyanide condensate

HC-36 polyurethane cyanide condensate reaction of NCO groups, OH groups and HN2 based resin made of polymer composite materials. Designed for cold, cold wind waterproof moisture barrier, gas for the vapor barrier. New cold storage warehouse inner wall painted in 150-200 m HC-36 polyurethane cyanide condensate, which can block out the cold air infiltration barrier warehouse outside of the hot air to penetrate inside the warehouse, thereby greatly reducing the working hours of refrigeration units, can saving 35% - 40% energy savings of 80 percent after five years, energy savings of 83.4 percent after eight years I produced the HC-36 cyanide condensate has been used three odd food Guangzhou Tai Qi Shandong, Guangdong food more than food companies, the effect quite obvious. I. Introduction HC-36 polyurethane cyanide condensate is a polyisocyanate compound and a terminal hydroxyl compound ester prepolymer reaction from the polymer composite materials. Single-component, moisture-curing, viscous liquid. The product after moisture curing film, cold storage, cold storage, cold storage waterproof to prevent water vapor permeable barrier material best. Its performance is currently no alternative to other materials. The product through the authority National Plastic Product Quality Supervision and Testing Center and other tests, the adhesion, flexibility, impact strength, waterproof moisture barrier, water vapor transmission are very excellent performance indicators and water vapor transmission coefficient. It can be a lot of energy-saving for cold storage, so the use of cyanide condensate S52-1 polyurethane efficient is your best choice. Second, the cold gas barrier layer of moisture and cold brushing life and saving an overview of the reform and opening up, construction of cold storage size small to large, from less to more rapid development throughout the country, especially in coastal areas and fruit development of vegetable growing areas more rapidly, it has occupied a very important position in the national economy, but the current is still some very serious problems in the design and construction of cold storage, cold storage leads to shortened service life and a serious waste of energy phenomenon, greatly improves the refrigerator's operating costs, weaken the competitiveness of enterprises. These problems have grown to the point where they must be solved. Cold storage (including: freezer, cold storage, cold storage), mainly refrigerated meat, aquatic products, fruits and vegetables and other food, cold storage life, whether it is for low-temperature energy-saving effect, or high temperature libraries and design is reasonable , construction is standard essential. I understand that in accordance with standard design and construction of cold storage, its insulation are better, storage temperature is relatively stable, the useful life of 40 to 50 years, no storage temperature fluctuations of the phenomenon, but in recent years the construction of a number of cold storage, Use basic retirement less than a decade, even continue to use its energy situation is shocking. Here are discussed in detail: Second, analysis of the problems (a) cold storage design some design units and individual designers, because of the cold moisture trap insulation recognize some misunderstanding from the beginning of the design of the cold storage works the existence and impact of the external environment on cold running muddled understanding that a gas barrier layer waterproof do it or not, has little effect on the refrigerator insulation, and some even think to do and not do, the choice of what the material is not much difference, so design this off, checks are not in place. (II) prejudice construction units. Construction unit bias is the main reason for the problem. For example, the construction of a cold storage unit on-site spray polyurethane foam insulation materials, but not set trap moisture barrier, even after some cold masonry mortar is not even wipe direct spray polyurethane foam layer, they mistakenly believe will foam since the crust, do they not know each spray a layer of crust regarded damage, hot and cold water vapor substantially in the absence of barrier, drive straight so severely damaged insulation, storage temperature rather unstable, to operate with cold storage to great difficulties. (Iii), the construction control is lax in the construction process, some of the functions on the one hand the main reason is not strict, the relevant state regulatory requirements of the cold storage building rules has not attracted the attention of the relevant departments of the State Technical Supervision Administration issued "Cold design specifications" have been separate the "Treasury gas barrier moisture" one. "When both sides of the retaining structure design temperature difference is equal to or greater than 5 ℃, it should be set at a higher temperature side of the gas barrier." But that is not listed as a mandatory provision, and therefore not stringent enough in the implementation, combined with cold storage from waterproof design to trap understanding of all aspects of the construction is not in place, the loss to bring our refrigeration business operations is very serious. Third, in order to solve the problem of cold storage building can meet the national industrial policy, energy saving, long life, in addition to reasonable matching refrigeration equipment, cold storage building must be a good grasp of this link. As far as I know, the cost of cold storage building insulation alone often exceed the cost of refrigeration equipment. Once the insulation is damaged, even the best refrigeration equipment does not help, I briefly described here to overcome the above problems. (A) should first be fully aware of the need for cold storage must be set to a gas barrier layer. Since the temperature of cold storage building envelope sides (or library, outer sides) is different, along with the transfer of heat, moisture flow movement also took place. This is called a mobile moisture vapor permeation. To block water vapor permeability is a certain difficulty. Even more difficult than blocking heat. The temperature difference between both sides of the envelope, it will cause a partial pressure of water vapor to form a dynamic vapor infiltration. For example, outside of cold storage (ie, the high temperature side) is 30 ℃, relative humidity of 60% water vapor partial pressure of 19.09mm Hg, low lateral 0 ℃, even if the relative humidity of 100%, the water vapor partial pressure only 4.58mm pump column. Thus, both sides of the envelope steam partial pressure (19.09mm Hg -4.58mm Hg). 14.51mm Hg, than a head pressure of 30-60mm water column ordinary fans is a considerable impetus - because the driving force. Bring water vapor pressure over the envelope of the cracks into the tiny pores library, this library for low temperature, it is to wet the pressure into the building envelope and insulation. Bring very negative impact on the storage body insulation. Especially for the gas it is particularly important, because in addition to water vapor into the retaining structure is not conducive to heat, it will also cause changes in the library gas is not conducive to fruit and vegetable store. In the water vapor partial pressure, driven by steam will penetrate outside the library to library. When the water vapor permeability to gas barrier inside envelope structure, the case of air-conditioning to the dew point or freezing temperatures (especially likely to occur in cold storage), the water vapor will be in insulation voids and cracks in the material, it is condensed into water or ice crystals, making insulation materials lower damp insulation, because the ice thermal conductivity is 2.0W / (M? K), about 100 times larger than the thermal conductivity of polyurethane 0.02W / (M? K), serious It will damage the insulation. Therefore, to ensure insulation materials to maintain good insulation properties, long life, maintain normal cold storage, set moisture on the surface of the insulating layer gas barrier layer is very important. (B) material moisture trap How to choose? Currently, the market of new moisture trap material has hundreds of species, such as waterproofing agent, waterproof powder, waterproof coatings and characteristics of different composite materials and so on. In short, the material used in the refrigerator, should focus its permeable, breathable (vapor) resistance, compressive (tensile) strength, aging resistance, low temperature resistance and presence of toxicity, and choose convenient construction, moisture trap gas, and durability, good mechanical strength and adhesion of strong material. Here are several physical, thermal performance of conventional moisture-proof insulating material :( see table) Material Name Density (kg / m3) Thickness (mm) Thermal conductivity W / (M · K) steam vapor permeation barrier permeability (m · h · pa) / g petroleum asphalt (350) 1139 1.5 0.27 1.35 * 10-6 1106.57 asphalt or a horseshoe ester 980 2.0 0.20 7.5 * 10-6 266.64 a felt two oil 1639.86 two felt three oil 5.5 9.0 Polyethylene film 3013.08 1200 0.07 0.16 2.03 * 10-8 3466.37 S52-1 polyurethane cyanide condensate 1100 0.20 0.10 4008.18 summary material properties and selection considerations when, the most important are three: First, the gas barrier material and separated hot material compatibility how? Second, vapor permeation resistance level how? Third, the adhesive strength of the material is good and strong grass-roots level? It is precisely because the three key factors that affect quality of the project. In the selection of more than six moisture trap material, if insulation is polyurethane, the best choice of proof polyurethane paint (ie, cyanide condensate), because the material stencilled on the base not only with the primary bond of more than 0.2Mpa strength, and has good compatibility with polyurethane foam, would not fall down. But asphalt material will not bond with the polyurethane. (C) how to set up a gas barrier layer moisture. Due to the infiltration process steam is always partial pressure of water vapor from side to side to maintain the structure of the partial pressure of penetration, it should put a small water vapor permeability moisture trap material is disposed in the higher temperature side, so water vapor on not enter the insulating layer, there will be no condensation in the insulating layer, ice and damage insulation properties. If moisture in the ground temperature gas layer side, it is easy to make maintenance of the structure to penetrate the insulating layer of steam leaving the insulation down effect, damage. Previously, we mentioned gas barrier should be set at the show proof insulation, but whether it should be provided on a surface or both surfaces of the side insulating layer should be set up? According to China's large land area larger temperature difference between north and south features, mainly to see the inside temperature and cold build the cold storage area in the cold or warm or cold areas zone, if the heat on both sides of the cold storage building envelope, cold state occurs when reverse conversion , then the hot side heat insulation layer is provided on one side of the moisture barrier gas barrier layer can be. If sometimes the inside than the outside heat (such as cold storage in many places in the north, low libraries in the Northeast), it should consider insulating layers are located on both sides of the gas barrier layer moisture. If the refrigerator is the use of color coated steel sandwich class or color aluminum sandwich panels for library materials, because water vapor permeability of the sheet is zero, so the ability to resist penetration of steam, that steam penetration resistance (m? H ? ps / g) is infinite, it has been able to eliminate the water vapor permeability, regardless of insulation thickness, thin, internal condensation phenomenon does not occur. This situation naturally do not need a gas barrier layer. But still need to use sealing seams better sealant material be sealed. (Iv) draw lessons, out of misunderstanding. According to nearly four decades of cold storage use, construction, maintenance experience shows that all cold storage and repair of severely damaged because of severe damp insulation caused mainly due to its severe moisture and gas barrier or damaged as gas barrier layer related. We had said at the beginning of this article a refrigerator with a less than 10 years can not be used again. It is due to the absence of the insulating layer and the insulating layer has been severely damaged. Cold storage is not just a large area outside the external walls of condensation, and a large area of ??the junction with a thick layer of ice, and the thicker end; in addition to a cold storage by the ice storage bin converted geothermal library after the outer facades for the same reason The same freeze the thicker end of the phenomenon occurred. Because it is not immediately shut down repair, only the compressor is running non-stop for 24 hours a day, barely able to maintain the storage temperature, increase operating costs 6? 8 times, and the lessons are very heavy. Could have been in cold storage for more than 50 years, but less than 10 years should overhaul, really runs the risk. In fact, the cost of gas barrier layer, but also 25 yuan / square meters or so, one of only comparable to the insulating layer (polyurethane foam cost of 250 yuan / square meters around) the tenth. That is to spend 10% of the money (you can also say that only the equivalent of 1.1% of the total cost of cold storage civil engineering) can recover 90% of losses. And those gas barrier layer can not be mistaken for "money" is not that an erroneous understanding of it? Fourth, the manufacturer recommends summary, if you do not set the key factors cold gas barrier layer moisture barrier of cold storage is much shorter service life and significant increase in operating costs, has become a serious impact on economic efficiency of enterprises. It is therefore recommended "cold storage design specifications" in Article 4.5.1 "is to maintain the structural design on both sides of the temperature difference is equal to or greater than 5 ℃, gas barrier should be set at a higher temperature side." Replaced by mandatory provisions. So as to effectively curb the problems.