Français
Powder spraying is also called spraying white, its main ejected material is added light calcium carbonate and alkaline precipitated silica (PH value is about 6.5~7, while the normal precipitated silica PH value should be 4~5). This type of filler has a high water content, which is greater in wet weather. At higher vulcanisation temperatures, these fillers will dissolve out of the vulcanised rubber surface as the water evaporates, or will subsequently exit the surface along the capillary channels formed by the evaporation of water, leaving a white powder after the water has evaporated. To solve the problem of powder spraying, first of all, do not use alkaline precipitated silica, in humid weather should pay attention to the filler moisture. If you are using a dense mixer to mix, raise the temperature of the rubber mixing discharge, so that most of the water in the mixing evaporate; if you are using an open mixer to mix, it is best to dry the damp filler before use. To identify whether the vulcanized rubber surface is spray frost or powder, the first step is to review the formula to see which is more likely to be sprayed, the second is to burn the fire, if the surface of the powder will melt or burn is spray frost; if there is no change in the form and colour of the surface of the powder after the fire is spray powder.
