Cold sealing machines are used for sealing cold seal style trapped blisters. These blisters consist of two pieces of board with a plastic thermoformed cup trapped in between. The two pieces of board can be loose, or attached making them into a folding type trapped blister.
The cold seal style trapped blisters are based on a pressure-sensitive adhesive, which is applied on the inside of the two pieces of board. Since this is pressure sensitive adhesive no heat is required in the sealing process. The only parameter required actually is pressure. Just a certain amount of force is to be applied on two pieces of coated board to create a strong and lasting bond between them.
One of the advantages of the cold seal process over the more traditional heat seal process is that only one parameter is involved, and therefore to be controlled. For any heat sealing process there are always three critical paramaters: Time, Temperature and Pressure. The latter is the only paramater to be controlled for cold sealing, making it an extremely reliable and stable process.
Another result is that cold sealing machines do not require any heat, making them much more energy efficient. With the removal of the heat from the packaging process, also any negative effects the heat might be having on the final result such as curving of the cards, discolouration of printed matter and deformation of thermoformed parts are not a problem anymore.
Lastly, the cold sealing is instantaneous, meaning that the moment the right pressure is applied the seal is created, there is no sealing time of any significance required, like in a regular heat sealing process.
A supplier of cold sealing machines is Ecobliss Blistermachines. They offer a full range of cold sealing machines from completely manual sealing devices to fully automated – and robotized – packaging lines. The semi-automatic and fully automatic machines include pressure checking systems, ensuring that every cycle the correct amount of pressure is actually applied. This makes it very easily into a fool-proof system with no risk of packs opening up in stores!