As more and more packages and processors convert to flexible packaging from more traditional forms of rigid methods including metal cans, PET and glass bottles or jars, they are confronted with the concern and challenge of how do they insure or equal the seal integrity levels from flexible packaging that they have come to expect from these more traditional packaging methods.

Insuring seal integrity on rigid packaging formats has not always been easy or guaranteed either, but time and technology has dramatically reduced and in many cases eliminated the risk of leaks on many rigid packaging methods for the experienced packager today.

Package seal integrity is particularly critical when packaging certain products including liquids, powdered product, retort food and refrigerated foods which typically utilize modified atmosphere “gas flushed or vacuum,” commonly implemented to maintain product freshness and extend shelf life. However, the importance of seal integrity goes well beyond freshness issues. For certain types of applications and processes the risk of poor seal integrity can be a critical health or safety concern.

The flexible packaging industry has worked diligently over the last couple of decades to develop comparable barrier materials to rigid. We have also custom formulated a wide array of sealants providing improved sealing strength for a variety of applications. However, the material substrate and sealant composition we specify are only part of the formula for hermetic packaging success. A number of other factors can influence the level of seal integrity which we can achieve in the actual packaging production environment.

Whether a packaging process utilizes pre-made pouches and fills and seals or utilizes rollstock to form, fill and seal, the most critical seal will be the seal through which the product is filled, typically the “top seal.” Product contamination in the top seal area is typically the most common reason for weak or top seal “leakers.” However, there are several other defects that can cause or contribute to poor seal integrity, including:

– Contaminants present in seal area during seal formation
– Improper seal bar “set-up” including temperature, press or dwell time.
– Separation of laminations due to inadequate bond strength
– Scratch or abrasion of any layers of the material that penetrates the foil or inner layers.
– Blistering due to voids in the bonded seal
– Wrinkles due to misalignment of the pouch in the gripper

I recently had the opportunity to attend a technical symposium at Packaging Technologies & Inspection (PTI) of Tuckahoe, New York. PTI has developed a proprietary seal integrity testing system for flexible pouch packages. The system inspects for sealing defects with its SEAL-SCAN™, non-contact, non-destructive airborne ultrasonic inspection technology.

The SEAL-SCAN™ unit pinpoints the presence, type and location of defects. The technology appears to be a significant breakthrough in pouch packaging quality control with several inline systems now installed performing 100% online top seal inspection for retort pouch packaging.

Packagers and processors are able to rapidly identify and correct problems with their fill/seal or form, fill & seal operations to ensure package integrity. Systems are available for both offline and online inspection capability. SEAL-SCAN™ moves quality control to the next level by verifying package integrity and analyzing overall seal quality, pinpointing the presence, size and location of a variety of common defects. The key is to identify and correct problems before package integrity gets out of control.

As we continue to move forward with transition of flexible packaging technology and our ability to implement it, it will continue to be the key to overcoming obstacles that are put in our path. “Sealing with Integrity” has and will continue to be a prerequisite to our industries’ continued success.