In the production of PVC foam board, the product sometimes has a large bubble hole resulting in the weight of those who do not come down. The advice given by some professionals is that the dose of foaming agent is not enough and the dose of foaming agent needs to be increased to improve the foaming effect. But if you follow this operation, you will not get the desired result.
The most used in the production of PVC foam board is the yellow blowing agent AC. When AC is added to the production, it will be decomposed by heat and generate a lot of heat, which makes the PVC foam board expand. At this time, the melt strength decreases, and the excessive number of small bubbles will fuse into large bubbles, hindering the normal foaming of the PVC foam board.
For this reason, we must add a foam regulator to remedy the situation, by increasing the melt strength, so that the bubbles are evenly distributed, thereby reducing the density of PVC foam board.
After adding the right dose of AC and foam conditioner, many small bubbles of uniform size will be formed. If the added dose of AC exceeds the enhanced melt strength range of the foam conditioner, the small bubbles will fuse together and form a large bubble.
So how do we solve the problem of large foam holes? First increase the amount of foam regulator or reduce the amount of foam, observe the output of PVC foam board. Then reduce the amount of foaming agent AC, if the problem of large bubble hole is alleviated, you can continue to reduce the dose until the desired effect.
In addition, in order to get better quality PVC foam board, it is recommended to add white heat-absorbing foaming agent in the production process to offset the excess heat released during the decomposition of AC.