EPP Raw Material Production Line
EPP
EPP (expanded polypropylene) is an engineering plastic foam material.By combining polypropylene resin with special additives and applying heat, pressure, and CO2 in an autoclave, the material is foamed into small plastic beads. These small, closed-cell foam beads are injected into a mold,where steam's heat and pressure are used to create custom molded part sin complex shapes.
Process Overview
Compounding & Modification (Single-Screw Extrusion)
PP resin + nucleating agent/antioxidant/color masterbatch → plasticization & mixing by single-screw extruder → pelletizing (strand or underwater cutting) → drying & screening → base pellets
High-Pressure Impregnation (Autoclave)
Base pellets + medium (water/dispersion agent) → autoclave injection of physical blowing agent (commonly CO₂, also N₂ or small amount of hydrocarbons) → absorption under controlled pressure & temperature
Pressure Release & Pre-Expansion
Controlled pressure release curve → gas nuclei form inside pellets → hot water/steam pre-expansion → EPP pre-puff beads suitable for molding
Aging & Packaging
Fluidized drying and equalization silo → screening and grading → antistatic/surface treatment → automatic weighing & packaging (bags or drums)
Output: Ready-to-mold EPP pre-puff beads with customizable bulk density.
Extrusion Part
The material is transported to the platform mixer, through high-speed mixing uniformly, then through the uniform drop hopper into the extruder,during the drop period to avoid the different density of a variety of materials caused by material extrusion stratification.
single screw extruder with high performance is adopted
Extrusion silk, through the sink cooling, after the wind knife to remove water.
The EPP strips are cut, dried,screened and packed.
Primary Foaming Part
Primary Foaming Part
The reaction stage of EPP reactor. (Automatic feeding, heating and pressurizing)
to dry the water of the particles after foaming, to break up the sticky particles
Density measurement and primary foaming control system
Unified curing bin
Secondary Forming Part
Secondary Forming Part
After being pressured by the prepressure tank and then into the secondary machine foaming, then dried in the curing bed. The finished product bin packing delivery will be done after being screened in the curing bin below the vibration.
EPP Application
Automotive industry: bumper energy-absorbing blocks, battery pack buffer layers, seat cores
High-end packaging: precision instrument shockproof linings, cold chain insulation boxes
Sports protection: helmet energy-absorbing layers protective gear
Industrial field: equipment shock-absorbing pads, building soundproofing modules
Consumer goods: toys
