Freshness and integrity are a magic combination when it comes to food and pharmaceuticals packaging because they lengthen the shelf-life of the container contents and boost the safety of recipients. But how do you achieve them? The answer is effective cap sealing.
Over-the-counter drugs such as analgesics, decongestants and antihistamines are frequently sold in rigid plastic containers, jars or bottles. The same container types are also often used for vitamins, minerals and nutraceuticals.
How these are sealed will have a significant bearing on the freshness and integrity of their contents. An effective seal will preserve freshness because it slows the degradation of food and medicines. On its own, however, a hermetic (or airtight) seal will not take care of the second criterion – maintaining integrity (and, thus, ensuring food safety).
The question of packaging integrity and safety came to prominence in the US in 1983 after seven people around Chicago died following the ingestion of Tylenol analgesic capsules that had been maliciously contaminated with cyanide.
EFFECTIVE & INEXPENSIVE?
In the aftermath of this tragedy, a regulatory requirement for tamper-evident packaging was enacted by the US Food and Drug Administration (FDA). This regulation demands one or more barriers to provide a visual indication of packaging integrity together with appropriate labelling to allow the end consumer to confirm prior to use that packaging has not been compromised.
Following the lead of the FDA, other major regulators around the world have since incorporated requirements for tamper-evident packaging into their own regulatory regimes and good manufacturing practice guidelines.
This, however, begs a fundamental question: how can you ensure effective tamper-evident packaging is provided inexpensively? One of the best answers is through so-called ‘induction sealing’. This involves creating a seal to the top of the container by applying the correct balance of pressure, heat and time to the most appropriate lining material.
Induction liners are highly-engineered layered laminate structures. They include a heat seal layer, chosen to match the material of the underlying container, a layer of aluminium foil to generate heat through induction, and a backing material for rigidity and to provide a resealing feature.
THE HEAT IS ON
With induction sealing, a multi-layer liner is placed inside the container cap. Once the cap is seated, aluminium foil within the liner is heated by electromagnetic induction, causing a layer of heat seal material to bond securely to the rim (or land area) of the container. This creates a strong, hermetic, tamper-evident seal.
Liners are available in one- or two-piece designs. One-piece liners are suitable for products that do not need to be resealed. Two-piece liners include a secondary backing board structure that allows the container to be resealed after the removal of the original tamper-evident seal. Before installation, two-piece liners are bonded together using a wax coating which disperses when the liner is heated.
Upper layers can be printed with standard inks. They can also be etched or employ holographic foil films, and covert printing is also possible to help the brand owner or retailer identify counterfeit products.
The laminated liner can be constructed with an easy-to-puncture feature or a half-moon centre tab that permits simple removal. Our own induction seal packaging range, Lift ‘n’ Peel, for example, incorporates an easy-open polyester tab designed to be simple to grip, flexible and extremely strong.
Clearly, the choice of liner and the induction system engineering should not be undertaken lightly. There is an excellent case for trialling both liner and induction equipment at customers’ premises; however, obtaining some initial advice from an experienced supplier is an important first step.
Manufacturers have the choice of several different strategies to include tamper-evident features on primary and secondary packaging. They include shrink wrap films, bands or wrappers; boxes with tamper-evident security seals and breakable caps.
A key challenge for many of these technologies, however, is that they can make access to products by legitimate consumers more difficult. The removal of breakable closures and certain seal types, for example, can require considerable physical strength or dexterity that may be challenging for the elderly or those with limited mobility.
Induction cap sealing is a technology that overcomes many of these limitations for rigid containers. Its multi-layer laminated liner inside the container cap provides a robust, leak-proof and tamper-evident hermetic seal.