Blister Packaging Technical Considerations

The primary packaging of a product allows for crucial protection from outside influences that can impact the safety, quality and efficacy of the product.

Knowledge of technical attributes of a film assist when selecting appropriate materials and these include:

Dimensional Stability

Since films typically run within a thermoforming process, dimensional stability of the webs allows the process to function properly. A web material that shows a consistent degree of change in dimensions in the cross and machine direction throughout the thermoforming range typically works well. PVC films are very common as this particular attribute helps a machine maintain good registration throughout the forming, filling, sealing, perforating, and punching operations used in blister packaging.

Thermoforming Properties

Selecting a film capable of handling a large thermoforming temperature range of allows for flexibility in the run conditions.

Commonly used thermoforming films typically form well when they reach about 115 to 125°C. After thermoforming, cooling the web to between 30 and 40°C will usually lock it into the final shape but still allow for some stress relief of the material.

Cooling of the web following the thermoforming process benefits the seal by not overly stressing the adhesive interface between the film and the lid.

Thickness Variation

Minimal variation in thickness ensures that sealing is consistent, reducing the incidence of leaks

Sealing

Since in most situations lidding materials such as foils have a heat-seal coating applied to them and the films do not, effective seal performance relies on reducing stress and thickness variation. There are many considerations and set points in the process that must be considered to ensure sealed blisters that are well-formed, maintaining good dimensional stability, no wrinkling, and leaking.

Perforation and Punching

Some blister packaging equipment makes cuts in the film in the form of both perforations
for tearing and punching to arrive at the final shape of the card. A good material must cut cleanly but also have a degree of brittleness which helps the user to tear the blister as required to separate the blister pockets.

Moisture Vapor Transmission Rates (MVTR)

Many active ingredients can degrade and lose their efficacy by reacting with water. The
moisture diffuses from the outside environment through the film and into the product. Monolayer films, such as those manufactured from PVC, polyester, and polypropylene,
offer a basic level of moisture vapor protection. In moisture-sensitive products, multiple-
layer structures made with PVdC coatings or other complex laminations are more suitable and have a lower MVTR.

Light Transmission

Films can deliver varying degrees of light protection based mostly on the UV absorbers and pigments used in either the base film of a multilayer structure or that of the monolayer film. Opaque films reduce the percentage of light transmission at certain wavelengths providing greater protection.

These are some technical considerations when selecting appropriate films in blister packaging.

Advantages of Blister Packs

Product protection

Blister packs act as a barrier between your product and outside elements, keeping it safe from damaging environmental conditions and impurities.

Evidence of tampering

Since blisters are designed to be torn in order to reach the product inside, there is obvious proof to consumers if their product has been mishandled or previously opened.

Versatility

Allow for high speed production, they are cost effective and aesthetically pleasing

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