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MPS

Pu heat preservation of pu heat preservation material 1

by:MPS     2020-08-02
< P> is depend on the quantity of heat. If there is no heat, foaming agent in the system can't evaporate, cannot generate foam. Heat from two aspects, one is chemical reaction heat; One is the environment < / P> < P> for heat. Chemical reaction heat is a constant value, not with the influence of external factors, but the environment provided by the heat along with the change of environmental temperature changes. When high environment temperature, environment can give reaction system < / P> < P> quantity of heat, can increase the reaction rate, shorten the reaction time. Performance for bubble foam, foam near surface and core density. When the environment temperature low ( Such as below 18 ℃) And part of the heat of reaction < / P> < P> to the environment. Heat loss, on the one hand, the bubble extended maturation period, increase the foam molding shrinkage rate, ( The lower the temperature, the higher the molding shrinkage) ; Experiment shows that the same foaming materials, environment < / P> < P> at 15 ℃ temperature foam volume is smaller than 25 ℃ foam volume 25%, on the other hand will form a layer on the surface of the bubble did not fully foaming don't even foaming hardcover, increased the bubble perfusion measure, improves the bubble < / P> < P> foam production cost. 。 2. Five factors the material and thickness of the shell shell thickness and strength is have a certain effect on the shrinkage of foam, generally in the same conditions, the thicker the thickness, the higher the intensity, bubble < / P> < P> the smaller shrinkage rate. Common shell material are stainless steel, color steel plate, embossed aluminum, etc. Embossing aluminum bubble caused by the coefficient of thermal conductivity big shrinkage rate is very big, gradually to be eliminated. Three Suggestions of foaming process conditions < / P> < P> according to the actuality of domestic, from the process performance of composite polyether and foam performance into consideration, we think the solar water heater of foaming process should meet the following conditions: 3. 1 temperature environment < / P> < P> temperature: in 20 ℃ ~ 35 ℃ advisable; A and B material temperature, high pressure foaming machine 20 + 2 ℃, low pressure machine 40 + / - 5 ℃. 3. 2 the mold ( Jig) For foaming process, how to keep the tank outer barrel deformation, < / P> < P> eccentric inner barrel is not always is a matter of great concern of the people, mould is a very important factor. The pressure generated in the process of the polyurethane foam in 0. 5 ~ 1. 0 kg/cm2, when water tank foam under pressure, < / P> < P> prone to deformation, it needs to have inner and outer mold to bearing pressure, at the same time, mould should have sufficient strength mould temperature should be controlled in 40 + / - 5 ℃, so that the foam rapid curing, the molding shrinkage rate fell to the < / P> < P>. In addition, according to the actual situation of the structure of the solar water heater to inner barrel filling the compressed air pressure within the barrel to make. 3. 3 foaming equipment completely eliminate the original manual foaming method, switch to < / P> < P> placer foaming, conditional manufacturers can use high pressure casting machine, flow must be in more than 500 g/s. Polyurethane foam, A and B material in the mixed foaming machine room stay time is very short, generally only < / P> < P> there are A fraction of A second to A few seconds, the mixing efficiency is A very important factor. 3. 4 moulded foam filling the best solution to solve the problem of bubble contraction should be adopt moulded foam filling, will the current widely used < / P> < P> many times pouring free foam instead of a pouring excessive filling, filling rate is 10% ~ 15% commonly, make sure that the foam gel before filling, eliminate gel after the formation of the bubble. 3. 5 mould < / P> < P> time temperature are the important factors that affect water heater open mold time, it includes the environment temperature and mold temperature. The high temperature, mould time is short. Solar water heater after foaming mould opening in about 12 min, in real < / P> < P> the production process according to temperature, filling amount, insulation layer thickness, extend or shorten the molding time. 3. 6 slaking follow the practice of refrigerator freezer, foaming materials after pouring, remove the barrel to 40 ℃ ~ 60 < / P> < P> ℃ heating way, under high temperature rapid curing process, prompting stable foam structure reduce shrinkage occurs. If there are no conditions, mould should be in barrel temperature 25 ℃ after < / P> < P> more environment aging more than 8 hours, and then moved to lower temperature ( Such as shipping department) 。 In order to ensure product quality and properties of the bubble, it is recommended that each manufacturer to establish solar curing area < / P>
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