More info about Resealable Stand Up Coffee Bags with Valves
Stand Up Coffee Bags
These are modeled after the traditional "tin tie" coffee bag, but use a zip seal instead of a tin tie and have a few extra features including a metallic poly liner and one way degassing valve. While these are most popular for coffee - these can be used for a wide variety of bulk food or snacks.
Resealable Zip Top
Instead of the traditional tin tie used on coffee bags - these have a resealable zip top - that also features a tamper-evident seal on top of the zip seal. There is a small notch and tab that can be removed to reveal the zip seal underneath. The reusable seal helps to keep ground or whole coffee beans from exposure to air, and doesn't degrade over repeated uses - unlike the paper bags that suffer from repeated folding and unfolding.
Four Wall Construction
One of the unique parts of this bag is that it's constructed from four separate parts that are sealed together. This allows the bag to have a separate flat bottom piece, which in turn allows the bag to sit flat and stand up easily. This is advantageous for shelving, storage, filling and presentation.
High quality coffee bags feature a small plastic piece called a "degassing valve." It's a valve that's designed to vent Carbon Dioxide that is released from ground or whole coffee beans. The valve is also a "one way valve" which means it only vents the CO2 out - and doesn't let air in (which will make the coffee go stale faster).
Heat Seal Top and Poly Liner
There are two main features to the liners of these bags. First, they have a Polyethylene (LLDPE) liner that protects both the outside of the bag and contents from seepage, grease, tearing, moisture and seals in flavor. The second feature is that the liner allows the open top of the bag to be heat sealed after filling.