Blister Materials
The History of Pharmaceutical Blister Packaging Materials
The packaging materials used in blister packaging make both the “cavities” or “pockets” to hold the product and the lidding used to hermetically seal the package. Materials are both polymeric and aluminum-based, and are usually referred to as the “formable” web and the “lidding” web. Many also refer to the formable web as the “bottom” web (because it is usually on the bottom during processing) and the lidding web as the “top” web (for the same reason).
Materials used to “form” the cavities or pockets are usually based on either PVC or aluminum. The PVC structures can be “mono” (only PVC), or coated and/or laminated with barrier materials like PVdC, Aclar® (PCTFE), etc. Aluminum structures used to “form” the cavities or pockets are called by various names: CFF (cold formed foil), CFB (cold formed blisters) or Alu/Alu are the most common. It is a laminate structure of aluminum sandwiched typically between PVC and oriented polyamide (nylon) films.
Lidding materials are primarily aluminum foil with heat seal lacquers and primers. Printing can occur either at the converters’ operation or online when the blister pack is produced.
The use of terms like “flexible” and “rigid” is a source of much confusion. People in the pharmaceutical industry speak of any blister films as “flexible” because they make flexible packages. “Rigid” packages are items like bottles, jars, etc. Polymer people relate “flexible” and “rigid” to the “flexural modulus” of the material under consideration. PVC films are available that are either “flexible” (plasticizer is added to soften the material) and “rigid” (material that is not softened by the addition of a plasticizer). For the purposes of this site, blisters will be referred to as flexible films.
The materials section traces the development of these technologies, the people behind those developments, and the companies that drove the structures into the industry. Click on the Navigation bar on the right to read more about pharmaceutical blister packaging materials.
The PVC film is generally either 200 µm (7.5 mils in the US, a slightly slimmer version) and 250 µm (10 mils in the US). These gauges traditionally offer sufficient material to form blisters of a size that conventional tablets, pills, and capsules can be placed in them and pushed out of the blister.
The PVC film is almost universally produced on a calender, is a “rigid” or “un-plasticized” material, with low residual monomer content and tailored shrink profiles.
Today the vast majority of the aluminum foil has a “universal” Heat Seal Lacquer applied to assure a good seal.
As early as 1953/54, BASF commercialized an emulsion-grade PVdC known by the trade name Diofan®. BASF developed the base coat/top coat concept and began selling Diofan 220 D (base coat) and Diofan 180D (top coat) to paper converters for its barrier and adhesion properties.
By 1966 pharmaceutical companies were searching for better barrier. Development projects started at this time and in 1969 DIOFAN PVdC coatings launched commercially on PVC films for pharmaceutical projects. While several technologies were used to apply the emulsion to the PVC and subsequently dry it, pharmaceutical films required a heavier coating that food and multiple-pass coatings were developed to meet this need.
There were four “pioneer” companies moving PVdC into the pharmaceutical industry: Two from Switzerland (Perlen and Aernie Leuch), VAW from Germany, and DRG from the United Kingdom. Here are their stories…
The polymer was extruded in Pottsville, PA, and the search for applications, markets and products began. Early applications included films used to protecting phosphors used in LEDs (prior to those phosphors being encapsulated), various military and aerospace applications, and the lamination of the film to other base films to improve moisture barrier. By the early 1970s laminating ACLAR® (the trade name for PCTFE film) to PVC for use in pharmaceutical blister packaging became the most important market.
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