Meltblown filter media for vacuum cleaner bags

What the meltblown layer does in a bag

Synthetic vacuum cleaner bags are usually built from more than one layer. An outer layer gives the bag its strength and shape and stands up to handling and to the dust and grit hitting it from inside. Behind or between these layers sits a meltblown layer that captures the fine dust.

Meltblown is made by pushing molten polymer through microscopic nozzles and stretching it with high-velocity hot air. The fibres are under 10 µm across and form a fine, even web. That fine structure is what lets a thin layer hold back fine dust while air still flows through it.

What to balance when you specify

A bag medium is always a balance between capture, airflow and dust-holding. A tighter layer catches more fine dust, but it can also raise the resistance to airflow and fill up sooner. The right point depends on the bag, the machine and what your customers expect from it.

• Electrostatic charging: a charged meltblown layer attracts and holds particles much smaller than the gaps between its fibres, which helps capture without closing up the web.
• Weight and evenness: thin spots let dust through, so weight must be even across the roll width and from roll to roll.
• Airflow: agree an air-permeability or pressure-drop target with us, measured the way you test your bags.
• Converting: the medium has to unwind, slit, combine with the other layers and seam cleanly on your bag-making line.

Which polymer?

Polypropylene (PP) is the most common meltblown polymer for air filtration. We also make meltblown in PET and PBT, which are used where a filter has particular temperature or liquid requirements. Tell us how and where the bag is used, and we will suggest a starting point.

Made to your specification

We do not sell standard stock grades. Every filter medium is made to order to the specification of your product. If you are replacing a meltblown you already use, send us its data sheet or a sample, together with the build of your bag and how you test it. Test our samples in a finished bag, combined with your other layers, not only as a flat sheet: a medium can behave differently once it is laminated or seamed.

Because we also make PP spunbond on our own lines, a spunbond layer can be specified alongside the meltblown and shipped in the same container.