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  • Effect of polyurethane foam temperature and time on product quality
    来源:http://motokone.com发布时间: 2018-05-17 09:02 Author: Polyurethane foam machine Source: http: // Published: 2018-05-17 09:02
    Generally, the ambient temperature is too high, the foaming is fast, and the gas generated inside is not easy to be exhausted, which will cause bubble aggregation. The ambient temperature is too low, the foaming is slow, the volume is small, and the density is uneven. When the ambient temperature is lower than 10 ° C, part of the reaction heat of the foaming material is radiated to the environment. The large heat loss will cause the foam curing period to prolong and increase the shrinkage of the foam molding. The test shows that the same temperature as the foaming material and the ambient temperature The foam volume at 10 ° C is smaller than the foam volume at 20 ° C 10}} 20} 0
    The temperature and uniformity of the mold temperature directly affect the speed of reaction heat removal, because the black and self-reacting reaction is an exothermic reaction. The mold temperature is low, the reaction heat is removed quickly, the foaming factor is small, the product density is large, and the skin is thick. The opposite is true for a high mold temperature. Generally, the mold temperature is controlled at about ℃ so that the foam quickly matures and reduces the molding shrinkage rate to a low level, which helps to form the uniformity of the overall density. In actual production, it is limited by the ten conditions and the mold temperature. It can be controlled at 25} 5 ℃, but the temperature should be kept constant and uniform as much as possible. The uniformity of the temperature of the large and concentrated foaming mold is very important. For example, the temperature is uneven, the foaming material spreads irregularly, and the flow is unstable, and the surrounding bubbles are formed, and the density of the entire board is not uniform.
    Effect of polyurethane foam temperature and time on product quality

    Effect of polyurethane foam temperature and time on product quality
    Generally, it is better to control the material temperature and ring temperature at 20-30 ℃, a little higher is also possible, and the higher the temperature, the shorter the curing time. However, it should be noted that if the temperature of the material is too high and the reaction speed is too fast, in the case of intense heat release, coupled with the low thermal conductivity of the polyurethane foam wood, the accumulated heat is not easy to be diffused, and a large amount of heat concentration will cause the foam " In addition, during the production of large-capacity refrigerators and large-scale cold storage boards, if the temperature is too high, the material injected in the early stage has begun to undergo a chemical reaction, and the viscosity will increase rapidly. This is prone to material blockage, causing local cavitation at the distal end. When the material temperature and mold temperature are low, the black material has a large viscosity, poor fluidity, slow or incomplete chemical reaction, and long foam curing time. If the demolding time is short, the injected material is still foaming, which is easy. Deformation makes it difficult to install the cold storage plate, and it is difficult to seal the refrigerator door. When the ambient temperature in winter is low, the temperature of the box, door, and board to be foamed is also low. At this time, it is necessary to preheat it, otherwise the chemical reaction of the foam will be greatly affected, and the foam will also appear. Does not stick to metal plates.
    When the foamed material is injected into the mold, it should be aged under a high temperature environment before demolding to allow the chemical reaction to complete. If the demolding time exceeds R., the curing will be insufficient, the foam will be deformed, and the demolding time will be too long, which will affect the yield. The variety of raw materials and the shape and size of the product are different, and the curing time and temperature are also different.
    Generally, it is better to be more than minutes. Generally, for every 1 cm increase in thickness of the foamed board, the holding time is 2 minutes. For ten refrigerator manufacturers), before and after the product is turned on, the cooling rate is checked, and the inspectors are required to observe the surface of the door and the cabinet to see if it is concave or not. Check whether the temperature everywhere is uniform and normal; record the temperature, time, unevenness and position inside and outside the box, and repeatedly observe, analyze, and summarize, which will help to get the best demoulding time and improve the efficiency.
    "Two points of products, eight points of foam", this is the industry's "lingo", there is a certain truth. The quality of the foaming process is a long-term practice and exploration process. Operators of many lines have rich experience, draw on their strengths, compile instructions for special process operations, monitor process parameters during production, and continually summarize and improve, which can produce high-quality products in a fast, good, and efficient manner.