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.