In both flexible and rigid foams, solid fillers are used for different aims.

Here some examples:

  • Calcium carbonate is used to increase foam density
  • Barium sulphate helps to achieve soundproofing heavy layer
  • Expandable graphite is one of the best fire retardant
  • Wollastonite, glass fibers and other mineral fillers confer to products particular mechanical property

Depending on physical and chemical characteristics, solid fillers can be blended with polyol in two different ways:

Into the batch

Solid fillers and polyol are blended with a premixing system, which allows to prepare batches of filled polyol and to supply them to the machine working tank.

The premix is composed by the following main elements:

  • Filler bag or big bag emptying systems
  • Transfer system for fillers from bags to premix tank: screw feeder or vacuum pump
  • Premix tank on weighting scale
  • Pump to transfer the blend to the foaming machine tank.

These kind of filled polyols are processed with A-Compact HF or HE Booster dosing units.

Into the mixing head

Solid fillers like expandable graphite, when blended with polyol, generate a “slurry” that can be injected directly into the mixing head.
Solistream is the Cannon solution to process the “slurry”.


  • One pressurized and jacketed tank with mechanical blade stirrer
  • Hydraulic cylinder or metering pump
  • Close-loop output control

Slurry can be automatically prepared by Cannon Solimix, which performs precise and continuous preparation of the batch mixture of graphite (or other fillers) and polyol (or other resins).
Cannon has developed three mixing heads to process filled polyol: RIMFPL/3 and FPL AN.