Base temperature and humidity
It can be seen from engineering practice that the base wall temperature also has a great influence on the foaming efficiency of polyurethane. During the spraying process, if the ambient temperature and the temperature of the base wall of the building are very low, after the first spray of rigid polyurethane foam, the reaction heat will be quickly absorbed by the base layer, thereby reducing the amount of foaming of the material. Therefore, the noon break time should be shortened as much as possible during construction, and the process should be arranged reasonably during the construction arrangement to ensure the foaming rate of rigid polyurethane foam. Rigid polyurethane foam is a polymer product formed by the two-component mixing reaction of isocyanate and combined polyether. Among them, the isocyanate component easily reacts with water to form urea. If the urea bond content in the polyurethane increases, the foam will become brittle and the adhesion between the foam and the substrate will decrease. Therefore, the surface of the substrate to be sprayed is required to be clean and dry, with a relative humidity of less than 80%, and be free of rust, dust, pollution, and moisture. No construction is allowed in rainy days. If there is dew or frost, it should be removed and dried.
The influence of the thickness of the spray coating on the yield
According to the thickness of the spraying, the application environment is different. The method of multi-layer spraying is usually adopted. According to the requirements of the national standard, the thickness of the first layer and the thickness of each layer have certain regulations. Follow the response curve of polyurethane to work reasonably. However, since each layer will have skinning, the larger the thickness of each layer, the higher the yield rate will be relatively speaking. However, in order to increase the yield rate, it is not advisable to blindly request the product in violation of the requirements of the polyurethane spraying process. It is necessary for the construction personnel to deal with it on-site with quality assurance based on experience.
The impact of construction on the exit rate
In the construction of polyurethane spraying, the waste of materials in the construction of corners, decoration lines, ceilings, beam structures, parapets, etc. is extremely serious. For example, in the construction of large corners, nearly 1/2 of the materials cannot be sprayed on the wall. In the ceiling construction, due to the small working surface of overhead spray construction, material waste is inevitable. Therefore, in the construction of special parts during the construction process, more attention should be paid to the unification of construction technology and construction conditions.
The influence of flatness on output rate
During the construction process, the flatness of the base should also be effectively controlled. The flatness of the base wall is too poor, which also causes a certain amount of material waste. In addition, if the flatness error of the base wall during the polyurethane spraying process is too large, the part with too large local positive deviation needs to be sawn off, which wastes polyurethane materials and labor costs, and also brings difficulties to subsequent construction.