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.

PVC is the cornerstone of the blister. The aluminum foil is coated with a heat seal lacquer to allow the PVC to be sealed to the aluminum. In the early years, this lacquer varied from market and from product to product, and sometimes dealt with sealing the PVdC coating rather than the PVC.

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.

The history of PVC packaging >>>

Foil Lidding Structures
The aluminum foil is general a “hard” aluminum. Again, the US and global markets were historically differentiated. In the US, where the imperial measurement system was common, most foil lid stocks were 1 mil thick, or 25.4 µm. In Europe the 20.0 µm thickness became common, and offered a slight yield advantage. In recent years the trend is to the thinner 20.0 µm film regardless of the market.

Today the vast majority of the aluminum foil has a “universal” Heat Seal Lacquer applied to assure a good seal.

The history of foil lidding structures >>>

PVdC Structures
In Europe, the first pharmaceutical blister packages for contraceptives resulted in the selection of blister packaging as the preferred package for oral solid dosages. This soon resulted in a search for better barrier. This search was both anticipated and mirrored by events in food packaging.

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 story of PvdC Structures >>>

ACLAR (PCTFE) Structures
Allied Chemical (now Honeywell) began development of PCTFE film in the early 1960s. An application for the trademark was made on June 19, 1961, and granted on March 27, 1962. The trademark application notes that ACLAR® is a fluorine-containing plastic in sheet or film form. The first use was August 11, 1960.

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.

Now – let’s look at ACLAR (PCTFE) Structures

CFF (Alu/Alu) Structures
Just a little more than a decade after the launching of PTP blisters for contraceptives found the pharmaceutical industry entering a period of major growth. New Active Pharmaceutical Ingredients (APIs) under development, new Drug Delivery methods were gaining favor, all resulting in the demands for new types of packaging – one that offered the advantages of blisters (PTP) and the barrier against moisture ingress of strip packages.

Now – let’s look at CFF (Alu/Alu) Structures

Return to Blister History Beginning




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