First, adjust the formula ratio, reduce MC and POP, and pay attention to the TDI index. There are polyethers on the market that can slow down the foaming speed. As for the brand, it is not recommended. As long as it is a polyether that can slow down the foaming speed, it is effective.
Then, the activity and quality of silicone oil. Silicone oil with high activity can decompose at the temperature to make the pores thinner. It is best to choose a new barrel of silicone oil to be relatively pure, and add an appropriate amount.
Secondly, reduce the use of catalysts and slow down the foaming speed; the opening effect of the opening agent is relatively weak.
Also, the speed and time of stirring. In the early stage, slow stirring is required, as slow as possible, and the time is controlled within a feasible range. After slow stirring, stop for 1-2 minutes, clear the white bubbles, stir slowly, pour TDI and stir quickly after a certain period of time. It is best to use a fan-shaped stirring blade, hollow in the middle, and two or four return baffles on the side of the barrel. Whether the stirring is slow or fast, the speed should be as uniform as possible.
From this, it can be seen that slow rise, full water foaming, lower material temperature, and good selection of silicone oil are crucial factors.
