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In the MeltBlown process, a thermoplastic, fibre-forming polymer is extruded through a linear die containing several hundred small orifices. Streams of hot air (exiting from the left and right sides of the die nosepiece) rapidly attenuate the extruded polymer streams to form extremely fine diameter fibres. The attenuated fibres subsequently get blown by high velocity air onto a collector screen - thus forming a fine filtered self-bonded nonwoven
MeltBlown web.
Essential features of the
process:
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Resin storage and resin preparation |
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Metering unit for main polymer, pigments and additives |
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Extruder for plastification of the polymeric components |
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Melt filter |
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Melt pipe to spin pump |
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Spin pump to maintain a constant throughput to the spinneret |
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MeltBlown
die head |
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Hot air supply |
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Conveyor belt
machine, height adjustable |
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Winding system |
Approx. 40% of the MeltBlown material is manufactured in a stand-alone process. The remaining meltblown materials are combined with spunbonded fabrics or laminates to form other materials. Combinations with spunbonded fabrics are primarily used to make nonwoven materials with barrier properties. Another variation is the combination of MeltBlown with cellulose or an absorbent powder, to produce a soft, strong but still absorbent material, which can retain absorbed liquid whilst still keeping its strength.
The following possibilities exist to influence the MeltBlown
process:
Polymer The MeltBlown process allows the use of various different polymers: polypropylene MFI 400 - 1500, polyethylene MFI 20 - 200, polyester iV 0,53 - 0,64, polyamide, polyurethane, polyphenylene sulphide. All of the polymers used during MeltBlown production must have a low viscosity. This results in a relatively high melt temperature (compared to other production processes). The melt temperature can be adjusted during production by means of electrical heating systems in the extrusion
section.
Components
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Preparation of raw material |
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Dosage unit for primary polymer, pigment pastes and additives |
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Extruder for melting and conveying the raw materials |
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Melt filter |
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Spin pump to ensure a constant throughput to the spin unit |
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Meltblown die to form the filaments |
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Hot air supply |
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Web forming machine for depositing the
filaments, height adjustable |
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Winder |
Physical properties
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Self-bonding / thermo-bonded |
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Large area-to-weight ratio |
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Adjustable pores and capillary structure |
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PP MeltBlown nonwoven material is hydrophobic / oleophilic |
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Excellent wick properties / liquid retention |
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High filtration efficiency |
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Thermal insulation |
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Elasticity |
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Preferred grammage spectrum 5 - 500 g/m² |
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Preferred filament diameter 1 -2 µm |
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Porosity |
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Surface energies |
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Colours can be used |
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.. and many others
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