Cause Analysis:
1 Excessive fit
The solubility of various additives in rubber is also different. The smaller the solubility of additives in rubber, the easier it is to excessively mix and cause blooming. The blooms caused by excessive compounding tend to drive other groups to spray together, although these blooms are far from saturated in the rubber.
2 Changes in temperature
The solubility of additives in rubber usually changes with the change of temperature. Generally, in this case, the solubility will increase when the temperature is high, and the solubility will gradually decrease when the temperature is lowered. Since rubber products are generally used at room temperature, once the outside temperature is lower than room temperature, some additives in the formula will come out close to their solubility, resulting in blooming. For example, the rubber shoes produced in summer have passed the factory inspection, but they are found to be frosted when they are stored in winter.
3 Undersulfur
The solubility of additives in rubber is affected by vulcanization. Taking NR as an example, under the condition of positive vulcanization, the density of crosslinking is the largest, the free sulfur is gradually reduced, the probability of sulfur spraying is also gradually reduced, and the chance of other additives to shuttle through the three-dimensional network is also greatly reduced, so frost spraying The probability will gradually decrease; on the contrary, in the state of insufficient sulfur, the network crosslinking density will be relatively small, and the probability of frost spray will increase accordingly.
