Heat sealing belts are generally used for plastic bags, pouches for food products and medical packaging. They are all sealed using heat. PTFE adhesive tape, referred to as Teflon tape, is widely used in the heat sealing of various thermoplastics.
Heat sealers are typically made by spanning a 2-3mm wide resistance wire along a heat resistant block that could be from 300mm to 1000mm long. The resistance wire heats up and melts the two thermoplastic layers together creating a seal between them. If the thermoplastic was in direct contact with the resistance wire it would melt and stick to it to prevent this we cover the wire with a PTFE coated glass cloth material.
PTFE adhesive tapes and PTFE zone tapes will resist heat up to 260 degrees Celsius which is normally high enough to resist the heat the wire generates. The PTFE is non stick which allows the molten plastic to easily release from its surface once sealed together.
There are three general types of options that can be used which are PTFE coated fabrics which are non adhesive backed, fully self adhesive backed and PTFE zone tapes. Non adhesive versions tend to be sold in a sheet from which are would across the resistance utilizing a reel to reel system. As the PTFE starts to wear it can simply be wound on. The fully adhesive backed versions tend to be used to site under the resistance wire and protect the more expensive block under the wire. This is done because it’s more cost effective the replace the PTFE adhesive strip than a damaged heat resistant block and it also offers come cushioning.
PTFE zone tapes are non adhesive tapes that have two strips of double adhesive tape down each edge that can bond to the sides of the heater block leaving middle clear which is in contact with the wire.