On PVC foam platics, usually we used AC blowing agent and NC blowing agent together
AC blowing agent(Azodicanrbonate), it is one type exothermic chemical foaming agent,,The decomposition
temperature is very high, can reach 200-205 degrees, this temperature is far beyond the PVC processing
temperature, so need reduce the decomposition temperature of AC blowing agent. At the same time, the
foaming rate is also high, about 190-260ml/g, The decomposition rate is fast and the heat release is great,
but the foaming time is short and the burst is strong.
So when AC foaming agent dosage excessive, gas volume is too large, the pressure inside the bubble growth,
bubble size growth is too large, rapid release of gas, the bubble structure damage, bubble size distribution
is uneven, and the formation of open pore structure, will produce larger bubbles and holes in the local.
NC blowing agent( white blowing agent), it is one one type endothermic chemical foaming agent, the
docompostions,tempreture abaot 130-140degree, foaming rate abaot 130, Although NC blowing agent
has low foaming rate, but it has a long foaming time and can be mixed with AC foaming agent, it can play
a complementary and balanced role.
AC foaming agent improves the gas generating ability of NC foaming agent. NC foaming agent can make
AC foaming agent cool, stability, keep AC decomposition and release gas evenly, inhibit the overheating
degradation of plate, and reduce residue precipitation
Therefore, PVC foam plastics usually use NC blowing agent replace part of AC blowing agent. Preventing
bubble breaking caused by AC foaming agent.
Usually advise dosage
AC blowing agent 0.3-0.5 phr,
NC blowing agent 1.0-1.2Phr