Blister Film

Blister Films for Protection and Presentation

The term “blister films” does not refer to a specific film material but is used to describe all films that can be used to produce blister packaging. Blister packaging consists of a thermoformed plastic film with preformed cavities for the product or products to be packaged. This part of the packaging is known as the blister. A transparent film can be used when the product is intended to be displayed for sale within the blister packaging. For many products, especially pharmaceuticals, white or colored blister films are often used. Once a product or multiple products have been placed into the blister, it is sealed with a backing card made of cardboard, another plastic film, or a metal foil. Product information is usually printed on these sealing films or cards. They can also be equipped with a hook or an opening for hanging on retail displays.

Types of Blister Packaging

There are different types of blister packaging, each with its own specific requirements for the blister film used.

• In so-called heat-sealed packaging, the front blister film is heat-sealed to the backing film. This type of closure also serves as a product seal and requires a sealable blister film.
• Clamshell packaging is a form of blister packaging in which the edges of the blister film are folded around the cardboard backing. This requires a blister film that can be bent when heated.
• In stapled packaging, staples are used to join the blister film front to the cardboard backing.

Requirements for Processing as Blister Film

The basic requirement for processing a material as blister film is that it can be thermoformed. This process is used to press cavities into the blister film that are adapted to the shape of the product being packaged. All blisters used in medical technology and the pharmaceutical industry, as well as many used in other sectors, are heat-sealed. This requires the blister film used to be sealable. If the blister itself is to be printed rather than the backing card or rear film, a printable blister film is required. If the product or products are to be visible to customers in the blister packaging, a transparent blister film must be used.

Typical Materials for Blister Films

Depending on the intended use, product requirements, and environmental conditions, different types of plastics are used for blister films.

• Polyethylene terephthalate (PET) is used for blister packaging primarily as amorphous PET (A-PET) and glycol-modified PET (PET-G). Both PET types offer high transparency, impact resistance, and good thermoformability. A-PET is particularly dimensionally stable and is therefore well suited for display packaging. PET-G can be thermoformed easily at lower temperatures, enabling the production of complex blister shapes. Both PET variants are fully recyclable and can be returned to the production cycle through the well-established PET recycling system.
• Polyvinyl chloride (PVC) is still a widely used plastic for blister films. It offers good formability, high stiffness, and transparency. PVC is easy to print and cost-effective. However, its disadvantages lie in its poor environmental performance: it releases chlorine-containing emissions when incinerated and requires plasticizers that place an additional burden on the environment.
• Polypropylene (PP) is more temperature-resistant than PVC and PET, making it attractive for blister applications manufactured by heat sealing and requiring sterilization. As a result, PP is frequently used in the pharmaceutical and medical technology sectors.
• Polystyrene (PS) is mainly used for simple, low-cost packaging with lower technical requirements.
• Multilayer films, such as GAG-PET, which consist of two outer PET-G layers and an A-PET core, combine different material properties in a single film, as do other multilayer films or laminates. The outer layers provide functionality such as sealability or printability, while the core contributes to the mechanical strength of the blister film or serves to reduce material costs.

Processing of Blister Films

To manufacture a blister, the blister film is heated and drawn into a predefined negative mold using a thermoforming process. This creates a precisely fitting cavity into which the product is placed. The blister is then sealed or otherwise closed with a lidding film or backing card. These can be made of paper, cardboard, metal, or plastic and often carry product information, for example in the form of printed text or labels. Hanging features, such as Euro slots, are also integrated into the backing card.

If sealing is used, certain properties of the blister film are required. The surface of the film must bond with the lidding layer under the application of heat without impairing the optical or haptic quality of the blister dome. Depending on the requirements, heat sealing, cold sealing, or high-frequency sealing processes can be used.

Areas of Application for Blister Films

• A particularly large market for blister films is the consumer goods industry. Toys, electronic accessories, tools, or household items are presented in retail outlets in transparent display packaging. The packaging protects the product, makes theft more difficult, and allows customers a clear view of the product they intend to purchase.
• In the cosmetics and personal care industry, blister packaging is used for razors, toothbrushes, makeup products, care sets, and similar items. A high-quality appearance and protection against contamination or tampering are key advantages.
• In the food industry, blister packaging is used for fresh or sensitive products such as ready meals, delicatessen items, meat, or confectionery. Gas-tight film combinations are used to extend shelf life and prevent loss of aroma.
• A major area of application for blister packaging is medical technology and the pharmaceutical industry. Here, blister packaging is used for medicines, disposable medical products, or diagnostic items. Blister films in this sector must meet high requirements in terms of sterility and barrier properties. Materials such as polyamide laminates, PVdC-coated PVC, or PET–aluminum laminates are increasingly used.

Sustainability Aspects and Disposal of Blister Films

Due to legal regulations and consumer pressure, requirements for sustainability and environmentally friendly disposal options are increasing for blister films, as they are for all packaging materials. For these reasons, traditional PVC blister films are being used less frequently, as they are difficult to recycle and release problematic substances during thermal recovery. PET films are considered a more environmentally friendly alternative because PET can be recycled as a single material and reused within existing PET return systems. Multilayer films pose a recycling challenge when they consist of different, non-separable materials. For this reason, blister films made from pure PET, such as GAG-PET, are gaining increasing importance.

Another development toward greater sustainability is the substitution of plastic components with paper-based backing cards or the reduction of film thickness while maintaining functional properties. The use of recycled content in film production is also increasing. Here again, GAG-PET film is a good example, as the A-PET core layer can be produced from recycled material.

Crucial to the environmental balance of blister packaging is the integration of the individual components into a functioning return and recycling system, which requires good separability of the packaging components. In general, pure cardboard packaging or cardboard packaging equipped only with a viewing window is more environmentally friendly than blister packaging.