Barrier packaging is all about shelf life and spoilage of the package contents.  Food spoilage is most affected by the presence of oxygen and moisture. Therefore if a package to keep a product fresh ask yourself the following questions.

1.  Do you want barrier to Water?
2.  Do you want barrier to Oxygen
3.  Do you want barrier to both Water and Oxygen?
4.  What is being packaged? 
5.  How long do you want it to last OR what is the required shelf life?

Rules of Thumb:
1.  HDPE is the best, inexpensive Moisture Barrier
2.  You need at least 1 mil thickness of HDPE to be effective
3.  1 mil of HDPE provides about 0.3 g/100 sq in/day MVTR
4.  2 mils of HDPE provides about 0.15 g/100 sq in/day MVTR and so on....
5.  Foil is the best barrier for Oxygen and Moisture but is also the most expensive
6.  Oxygen barrier usually falls into one of three categories:            

A.  1 to 5 cc/100 sq in/day - short shelf life, 2 weeks to 1 month. This can be achieved with a nylon coex or lamination

B.  0.1 to 0.5 cc/100 sq in/day - medium shelf life, 3 months to 1 year.  This can be achieved with a nylon/EVOH coex or lamination

C.  0.005 to 0.01 cc/100 sq in/day - extended shelf life, 1 to 3 years.  This can ONLY be achieved with specific laminations

Table of Typical values for Reference (1 mil thickness):Note:  Some published data may be slightly different.
     
Product:                    OTR                MVTR          
                               (cc/hsi day)     (g/hsi day)

Nylon 6                     2.6                 19
Oriented Nylon 6         1.3                 10
PVDC coated Nylon      0.5                 0.2
Metallized Nylon          0.05                0.2

PET                          4.5                  1.2
PVDC coated PET        0.4                  0.9
Metallized PET            0.08                0.1
    
PP                           350                  1.75
Oriented PP               250                  0.5
Metallized PP              3.0                  0.02

HDPE                        185                  0.3
MLLDPE                     390                  0.7
LLDPE                       500                  1.2
LDPE                         500                  1.3

Please keep in mind that depending on the supplier and the way in which the specific product is made that these table values will change slightly.  However, they can be used as a guide when selecting the appropriate structures for use.

Polymer Packaging, Inc. is a nationally-recognized, award-winning manufacturer of multi-layer coextruded and biodegradable films, Inno-Lok prezippered roll stock for form fill and seal, printed films, stand-up pouches, coated and non coated wovens and non wovens, housewrap and machine direction oriented (MDO) films.  Please consult any one of our customer service or technical staff to answer your packaging questions today! (800) 260-1446 or (330) 649-6000. 

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