In testing package barrier it is important to have a film and sealing mechanism capable of producing hermetic seals. The question which arises is how would you test a film and lamination for hermetic seal performance and in particular the seal jaw range over which you can achieve a hermetic seal. For just like seal range for heat seal strength, the formation of a hermetic seal with a film can occur over a range of seal jaw temperatures for a fixed packaging material. The purpose of the test would then be to compare various sealant films in a lamination to see how robust a hermetic sealing process a film will give. Robustness being defined as how wide the hermetic seal range compared to the temperature variation of the seal jaw during bag production.
In general, you will need to define the basic parameters for the package, such as: Example 1, an 18 micron metallized film laminated to a second printed 18 micron OPP film with 12 microns of LDPE. An alternative would be example 2, a lamination of surface printed 30 micron white cavitated film adhesive laminated to an 18 micron metallized OPP film. Having defined the structure of interest, you now have a structure you can screen for the sealing film (often metallized) performance but you have to then choose the type of packaging machine you will use and the packaging speed. An example of a hermetic seal test used for the development of a hermetic sealing metallized film is described in US Patent 5,049,436 which is described below.
To test for hermetic seal, bags were produced on a Hayssen Ultima II packaging machine using the first laminate described above in example 1. The machine was operated at standard conditions of 65 sealed bags per minute, lap seal arrangement, at 150 lb. jaw pressure, over a range of jaw temperatures. The bags were submerged in water under an eleven pound (5 Kgm) weight and the location of any leaks recorded.
The test determined the jaw temperature range (sealing range) in which hermetically sealed bags which were 100% leak free were produced with the film.
The use of the film of example 1 resulted in leak-free bags over Hayssen jaw temperatures of 121 C (250 F) to 149 C (300 F), a range of 28 C (50 F). In addition, in processing the film of example 1 into hermetically sealed bags, the packaging machine ran with no operability problems, such as film jams.
So as you can see there can be a test developed to determine the performance of a particular film for a particular function (hermetic sealing) which can be used to compare various film components in a lamination.