How to choose foaming agent in the process of PVC products?

1, in the production of PVC foam board, if only a yellow blowing agent, do thick boards are prone to break the wall and bubble holes, the reason is due to the decomposition temperature is high, in the barrel of the early volatilization of less, in the late out of the mould when the instantaneous outbreak, so it leads to easy cracking.

1, in the production of PVC foam board, if only a NC white blowing agent, due to the decomposition temperature is low, the amount of gas is small, early decomposition, out of the mould is a large number of volatile, so do the low density of the board to do not come down; if the amount of blowing agent to add too much, the pre-evaporation of more gas to the flow of the material inside the cylinder to create an obstacle to the flow of the material, perhaps resulting in plasticisation is too good, so out of the board is easy to yellowish colour.

2, reconcile the solution: processing NC white blowing agent, taking into account the delay time, so it will be used lubricants to the blowing agent through the mixer mixing, coating, increase mobility, etc., to improve the decomposition time.

3、According to the production of different densities, the proportion of AC and NC blowing agent will be reasonably proportioned to achieve balance. But the total amount of two kinds of add up is too much, it will also lead to a large amount of gas produced inside the barrel in advance, thus affecting the fluidity. Due to do foam board need to flow fast to impact the mouth of the mould, and need to have enough gas to meet, so the amount of foaming agent is too little and too much, will affect the density of the reason for not reaching the goal.

Mutual influence factors

1, if the formula system mobility is too good, the change of the amount of foaming agent, especially outside the lubrication more and less, the amount of foaming agent should be calculated properly. Then the amount of foam regulator and the amount of foaming agent should be calculated appropriately, otherwise it will lead to waste or affect the force when the mouth of the mould.

2, the use of lead salts, calcium and zinc, organotin or rare earth and other different stabilizers, the proportion of foaming agent parameters are not in a law.

3, the screw's influence on the blowing agent:

A screw plasticising good and poor, other costs of course, there are big changes, these are not mentioned first. On and foaming agent only, poor plasticising screw, relative foaming agent will be used less; plasticising over the good screw, foaming agent will need to appropriate more. Also, the screw and regulator is quite relevant.

1, the relationship between mould and blowing agent:

To produce stable and good quality products, the discharge speed and back pressure of the mould are very critical, and this is also very much related to the amount of blowing agent, and the amount of regulator is also directly related.