Note: This is the second article of a three-part series covering medical plastics packaging (1) trends, (2) material/process advances and (3) applications.

It is projected that ongoing medical packaging research and development will continue to produce sophisticated, technically advanced products. This includes smart films that absorb or emit various gases, films that incorporate antioxidants that are gradually diffused into the product, or ozone-emitting antibiotic film.

A range of other films for medical packaging anticipated or in various stages of development include water-soluble films with a controlled solubility rate, new films that can be gamma or electron-beam sterilized without degrading and down-gauged high-tensile-strength film. Films that are resistant to ultraviolet light, medical packaging films that will tolerate high processing heat, silica-coated films that impart both barrier properties and clarity, and finally bio- or photodegradable films suitable for medical packaging are also being developed.

To start with, Aclar Flex, a moisture barrier film designed for medical flexible applications such as overwraps, medical bags, pouches and lidding crystal clear polychlorotrifluoroethylene (PCTFE) film fulfills a market need for transparent high-barrier medical packaging protection. Produced by Honeywell Specialty Films using a special manufacturing process, it provides up to 10 times the barrier protection of conventional transparent packaging films such as polyvinylchloride (PVC) and polypropylene (PP).

Honeywell Specialty Films
Aclar flex moisture barrier film.

In addition to its excellent moisture barrier properties, the film is biochemically inert, chemically-resistant and plasticizer/stabilizer free, while its flex-crack-resistance exceeds oxide-coated barrier films and foils, and it can be sterilized using an autoclave or other sterilization methods. Moreover, the film is metal detection system friendly.

These properties make Aclar Flex fluoropolymer film extremely useful for packaging a variety of medical devices, diagnostic kits and other medical applications, including new drug delivery technologies providing medicine that patients wear, is inhaled or dissolves in the mouth, as well as micronized pulmonary delivery systems. The film's exceptional clarity permits healthcare staff and end users to visually inspect and identify contents of packages that once were opaque simplifying quality control and reducing medical errors.

Chemical inertness allows contact with special medical solutions, diagnostic reagents, and pathology specimens and it can be sterilized using heat, gas, or gamma/beta irradiation. The film also laminates well to virtually any flexible or rigid substrate including PVC, PETG (amorphous polyethylene terephthalate glycol modified), copolyester, amorphous PET and PP.

Next, films that make use of polyvinylidene chloride (PVdC) coated PVC are broadening protective blister packaging options to provide more cost-effective, higher-barrier film alternatives. Some of these recently developed films use Solvay's Diofan Super B grades of PVdC.

This high-crystallinity PVdC offers greater barrier per unit weight than standard PVdC such that use of this next-generation PVdC allows processing costs to be minimized with fewer coating passes needed. In this way, Super B offers new options to undertake development of higher barrier films with lower coating weight and will redefine the mid-barrier range threshold, resulting in higher-barrier films that measure favorably against higher grades of PCTFE.

Water vapor (left) and oxygen (right) transmission rate comparisons.

Continuing, Klöckner Pentaplast's triplex configured PVC/PVdC/PVC film, Pentapharm alfoil E S03, employs Solvay's Super B PVdC, high-crystallinity PVdC dispersion with better barrier properties and heat resistance than standard PVdC. The transparent film, an extension of the leading film producer's PVdC coated polymer film product line is flexible enough to support bending without cracking and has barrier properties comparable to high barrier grades of Aclar.

These new films are the only high-moisture/oxygen barrier PVdC-coated films that have a three-layer symmetrical structure designed for higher performance on packaging lines. The films thermoform in the same temperature range as PVC mono film, and the PVC skins provide a low coefficient-of-friction to prevent blocking on preheat plates and supply more consistent material flow during the thermoforming process. These films seal well with all standard vinyl compatible lidstock and comply with U.S. Food and Drug Administration pharmaceutical packaging requirements.

The Pentapharm alfoil E S03 is an economical barrier alternative to Aclar lower barrier grade films and provides a good cost/barrier ratio relative to standard PVdC films. For instance, a 120-gram-weight Pentapharm alfoil E S03 film has twice the oxygen barrier characteristics of a 90-gram weight film using standard PVdC.

Klöckner Pentaplast
Pentapharm high barrier films.

Moving forward, the demand for packaging with high water vapor transmission rate (WVTR) barrier is growing significantly. In response, Perlen Converting LLC has developed Perlalux Tristar ultra (PVC/PE/PVdC; polyvinyl chloride, polyethylene, polyvinylidene chloride), which offers the company's highest level of moisture and oxygen barrier protection in a PVdC film.

The film utilizes a 120-gram-weighted PVdC, with a proprietary PE tie layer. The blister packaging barrier film provides the highest barrier properties of any PVdC film on the market offering moisture barrier equivalent to PCTFE films, at optimum cost efficiency, while also delivering high oxygen barrier protection.

Perlen Packaging
Perlen specialty films water vapor transmission rate comparison.

The film allows diffusion of 0.11 grams of water/square meter (38 degrees C, 90 percent relative humidity over 24 hours), an increase in barrier from Perlen's StarFlex film (PVC/TE/PVdC; polyvinyl chloride, thermo-elast coating, polyvinylidene chloride) using the same gram weight of PVdC material.

Delving further, KAA TIMEX LR's GuardLid, aluminum-based pharmaceutical blister foils provides child resistance characteristics to prevent children from gaining access to medications and assists pharmaceutical companies in their compliance with child resistance legislation.

The alufoil-based laminates contain either polyester or oriented polyamide film and paper and offer the necessary puncture resistance and enhanced peelability required to meet U.S. and European child-resistant standards. KAA TIMEX LR offers the pharmaceutical industry a range of child-resistant blister lidding foils in peelable and peel-push alternatives.

GuardLid blister foil.

Carefully engineered bond strengths are used to provide the necessary peel-push, peel-open or tear-open features desired for the final product.

Finally, a blister packaging design program, Pentapharm BlisterPro, developed by Klöckner Pentaplast, is a CAD simulation tool and finite-element modeling software program for thermoforming pharmaceutical blister packages. The software, which is intended to improve film selection, allows package designers, technicians and engineers to explore the effects of tool geometry, film characteristics and process conditions before running actual experiments thereby avoiding expensive production line trials and tooling costs.

The program provides thickness distribution, surface area and barrier evaluation/permeability estimates of CAD simulated thermoformed cavities. Using these calculations, package engineers are able to design optimal blisters considering product shapes and barrier requirements. In addition, the software can serve to study barrier improvement and optimization for existing tools and films and can relate cause and effect while addressing constraints.