Lamination Sealant Layer

polyethylene LDPE flexible packaging examples

The sealant layer of a flexible lamination package is a critical component. Whether the application is Vertical Form / Fill / Seal VFFSstand up pouch, plastic reclosable zipper packaging, or quad seal square cube packages, the sealant layer must:

  1. be corona treated to the proper dyne level to accept either solvent or water based adhesives. The sealant layer is laminated to an outer layer usually of polyester (PET) or polypropylene (PP).
  2. Heat seal through contaminants both liquid and dry in an often hostile environment. The hot tack / melting point must be substantially lower than the outer layer for sealability.  The sealant layer must prevent “channel leakers” when a foldover wrinkle occurs.
  3. be clear for product visibility
  4. have a low COF for machinability
  5. be FDA and Kosher approved for prolonged and direct food contact in food grade packaging

sealing through contaminants

“Complete” baking mixes are problem children because powder will inevitably get trapped in the seal. Cocoa powder and powdered milk are more difficult to seal through than fat.

The lingo of multilayer packaging can be confusing.

Watch this video to learn about VFFS hot fill packaging.

Metallocene polyethylene resins provide better fast tack than EVA without the odor and taste transfer associated with EVA.

Providing barrier properties does not have to be part of the sealant layer’s job description. If the sealant layer must provide a barrier, there are two ways:

  1. use a coextruded EVOH core layer film.
  2. laminate to a Saran™–coated (PVDC) polyester or polypropylene.

We make many grades of sealant layers. Our workhorse is  622.

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