Brief introduction of epp production method in foamed polypropylene

(1) In-kettle impregnation method:

Putting PP beads in a kettle, soaking them in butane at a certain temperature and pressure, and then suddenly reducing the temperature and pressure to make them expand and foam, this method is simple, practical and quite complicated. At present, only Japanese companies have mastered it, and it is said that the cost is high and technology will not be transferred. Japanese JSP and Kaneka companies have factories in Wuxi and Suzhou, and their confidentiality is very strict. Generally, PP beads used by impregnation in kettle are produced by stretching cooling method, which has low yield and trouble. Our company has successfully developed the thermal cutting method, and the bead size is 1- 1.5mm, which is very uniform, and the single machine output can reach more than150kg/h. ..

(2) Extrusion method (Germany):

Put PP and binder with high melt strength into an extruder, add foaming agent (such as butane) after melting to make them fully and evenly dispersed, cool and extrude from the die hole, foam due to sudden pressure drop, cut into small beads in time, and quickly cool and set. Three years ago, Pujiang District of Chengdu introduced a bead production line with an output of 80Kg/ hour from German Bell Stilloff Company, which cost 6.5438+million yuan. So far, the trial operation has not been successful.

Secondly, the production methods of EPP products are briefly introduced.

Generally, EPP beads are put into a charging tank (even if the beads are filled with air with a certain pressure), and then compressed air is injected into the mold of EPP forming machine through a spray gun, and steam is introduced to further expand the EPP beads, so that their surfaces are welded together to form. After cooling, the mold is stabilized at a certain temperature to obtain EPP products.

Third, raw materials for EPP.

Instead of ordinary polypropylene (PP), high melt strength polypropylene (HMS-PP) was used.

Generally, the molecules of PP are planar (without branching), so it must be branched after treatment, which is also commonly known as PP grafting (ordinary grafting will degrade and fail to achieve the purpose of making it have high viscosity and high melt strength). At present, it is known that Nordic Chemical and Basel can produce HMS-PP. ..