Have you ever wondered or thought about the packaging sealability of your product? In case this word is completely unknown to you, the literal definition of sealability is:
“the property of being seal-able.”
When striving for high quality packaging the product can’t just ‘ be seal-able’. You don’t want it to open or break somewhere during the production process. However, you also don’t want a seal to be too difficult to open. This is why we think the definition is more along the following lines:
“having packaging seals (often layers within our laminates) that perfectly melt together at certain points, without the rest of the packaging being changed/suffering from the heat.”
Just as important are the effects that sealing has on the rest of the packaging. Without using the proper packaging concepts your entire packaging will suffer during the sealing process. This is because not all inks or films are equally resistant to the heat and pressure that is used during the sealing process. Each film has it’s own temperate from which it starts to seal, also known as the seal ignition temperature (S.I.T.). To protect your packaging, you want your seal layer to have a much lower S.I.T. then the melting point of your other layers.
Our thoughts on improving the sealing of flexible packaging
There are mostly three important factors to take into consideration, when striving for the perfect seal on the packaging machine. These are:
Pressure is needed for sealing flexible packaging. Although it can be of great importance, adjusting the seal pressure is often overlooked as an option. To much seal pressure might lead to material deformation, while too little seal pressure might lead to less seal strength. Finding the right seal pressure depends on several circumstances, for example: the packaging material, machine and parameters.
An important factor for sealing is sealing time. Sealing time is the amount of time that is used to seal the packaging. The longer the seal time, the warmer the material gets. Of course a certain amount of time is needed to reach the seal temperature of the flexible packaging. However, increasing the time used for this process is not always an option as it might lead to a slower filling process. In these cases other formulations of the laminate might lead to better sealability.
This is where most changes are generally made on the packaging line. The temperature of the packaging machine can often be changed without large repercussions. With the right seal temperature the seals will be strong, furthermore they will look smooth and consistent. The best temperature is greatly dependent on the type of seal layer used per flexible packaging concept.
Our thoughts on improving the product
Of course aside from looking at the seal parameters one can also look at the packaging concept used. Choosing the right materials for a high sealability is very important. For example, just with a PE mono film there are many different variations of film that all have their own distinct properties (where some will seal more easily then others, but have other drawbacks). One example of such a film is a special quality hot-tack film. Hot-tack films are used because they are already close to full strength during the cooling process. This might be important when filling a higher amount of weight in a shorter time. General films would still be weaker during the cooling process and take longer to regain their structural strength.