Bulk and Heavy-Duty Bags

Bags made of woven fabric do not generally provide sufficient containment for liquid products, so such bags often incorporate a film liner. Polyethylene is used most often, but aluminum foil or PVDC copolymers can be used to provide improved barrier ability. The liner may be a single material, or have a multilayer construction. Alternatively, the bags can be coated with PVC or latex to make them waterproof. Liners can also be used in bags for solid products. Often the liner is designed to be disposable to facilitate reuse of the bag. 

The bag seams can be heat-sealed or sewn, depending on the material and the application. Some bags are made from tubular material, so sealing is required only at the top and bottom. Others have seams at the back, bottom, and top or they can be made like three-side seal pouches, with a fold forming the bottom of the bag. 

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