Forming Tactics for Blister Films

Barrier films can create line performance challenges.

In blister materials, pharmaceutical companies' first priority is protecting the product, and at the lowest possible cost. Material performance on the packaging line is another issue to be considered, with pharma firms focused on improving line uptimes and speed.

Blister line performance is contingent on many factors. Line output is affected by feeders, wallets, and cartoners, for example. Companies, however, can often improve speeds and costs with alternate blister materials, one converter argues.
 
“Companies don’t realize they are really leaving a lot of money on the table by not moving to better performing materials. They will look at immediate savings, but if you want to drive out costs, the return is not in the packaging but in the performance,” the converter says.
 
The opportunity with alternate materials aside, higher barrier and more complex structures—increasingly adopted for protecting sensitive solid doses—tend to be more difficult to process than straight PVC.
 
“When you have more layers in a laminate, generally the processing is more challenging. You have to hold tight tolerances, and you may have to run at higher temperatures. As you go up the barrier chain, you tend to sacrifice the operating window,” says Justin Schroeder, director of marketing and development, Anderson Packaging Inc. (Rockford, IL).
 
“We are seeing broad adoption of multilayer barrier structures in new products, much more so than traditional monolayer PVC and PVdC laminates,” Schroeder says.
 
“We have a lot of experience running a wide range of blister films, so we bring our knowledge to bear in addressing these material issues,” he adds.
 
“Curling is an issue with Aclar laminations, but we see curling across all films. We have designed and implemented proprietary technology to mitigate the curl and get better handling,” Schroeder says.
 
PVdC films present off-gasing issues, as gas released in processing corrodes tooling. Anderson pre-coats the dies and performs preventive maintenance to help reduce the effect.
 
The contract packager runs a gamut of thermoformable films and cold form foils, and has tested PP, EVOH laminates, COC, and desiccating film in trial runs.
 
“Customers have not requested these experimental films to be implemented commercially. Even if there is a potential cost savings or perceived “greener” foorprint, the operating window with (these films) is generally narrower and presents challenges,” Schroeder says.
 
Schroeder notes that films’ machine performance advantages may be less evident to a contract packager with fragmented runs of different packages than with a pharma company making the same product in-house day after day on the same machine.
 
“We run the spectrum of customer personalities. Some companies are more cutting-edge and will want to experiment with films’ benefits. [But] the majority of companies are reluctant to switch films once they have completed stability,” he says.
 

Blister Card Designed to
Simplify Assembly

The Keystone Folding Box Co. offers the child-resistant, senior-friendly Key-Pak, which comprises a single component to reduce assembly, inspections, engineering, and tooling. Offered as a cost-effective solution for clinical trials, compliance dosing, physician’s samples, and retail applications, Key-Pak is a traditional fold-over, heat-seal blister card that has achieved an F=1 child-resistant rating in CPSC protocol testing.

A zipper design on the back side of the card allows for clean and simple removal of the rear blister card panel and provides damage-free dispensing of the product. The package is compatible with both thermoformed and cold formed blisters. The company claims that the custom heat-seal board allows for shorter sealing time, fewer production defects, and minimal exposure of the product to heat
.

DESIGNING QUALITY IN
Companies have significant opportunity to increase performance on materials they are already using, says Angela Roggenhofer, senior associate, Montesino (Wilmington, DE).
 
“We see a lot of room for improvement in using existing materials and machinery correctly. The silver bullet is applying what we already know or what companies should know about existing materials,” Roggenhofer says.
 
Performance is optimized by designing the most suitable materials and processes in from the start in a Quality by Design approach. “You base your specifications and validations on [existing] scientific knowledge. Then you are managing the risks instead of avoiding the risks,” Roggenhofer says.
 
Most companies running straight PVC validate their machinery at the middle of the forming window provided by the manufacturer, with a tolerance of 5 to 10 degrees. “This is missing PVC’s sweet spot forming temperature. They are forming at a higher temperature than is needed, which introduces material stress and the potential for curling, wrinkles, and leakers later on,” she says.
 
Blister simulation software can be used to shed understanding on the materials and optimize blister cavity geometry. Using software simulation, engineers can achieve more consistent quality and reduce set up times and waste. Montesino offers the BlackBox simulation software.
 
“These solutions have been available for years, but many companies don’t use them. PVC is very forgiving. You see the biggest improvement [using simulation software] with barrier materials,” Roggenhofer says.
 
At Anderson Packaging, tooling and 3-D blister modeling is done in house using a CAD-based system that sends computer-modeled designs directly to CNC machine for tool making.
 
“You can mitigate a lot of performance issues with the correct design and tooling, Schroeder says.
“We implement best practices from our experience across all the products and films to ensure optimal performance for each new customer and product. This allows for efficient startup and speed-to-market.”
 
Perlen Converting LLC (Whippany, NJ) compared its PVdC and Aclar films for packaging line performance in recent testing. Films included Perlen’s Perlalux TriSta Ultra 180-gram weight PVdC (PVC/PE/PVdC) launched last year.
 
ACLAR VERSUS PVDC
Testing was undertaken on a mid-sized high-performance blister line at contract packager Salutas Pharma (Barleben, Germany). Blisters with 40 mm × 92 mm dimensions containing ten convex tablets were manufactured. Cavity forming depth was 4.8 mm.
 
“In this testing, we looked at films’ impact on line runability, speed, waste, energy use, and blister output,” says Fredy Brunner, regional sales director, North America, Perlen.
 
Direct comparisons were made between the 180-gram weight PVdC and Perlen’s Aclar 3000 (PVC/Aclar), and between Perlalux TriStar Ultra 120-gram weight and Aclar 2000.
 
TriStar Ultra 180 demonstrated good forming and sealing at heating and sealing temperatures similar to Perlen’s lower-weight PVdC films. The film achieved 250 blister-per-minute output with heating of the platen at 120°C. Without the cartoner running, output of 300-per-minute was realized.
Perlen Converting has increased PVdC-coated film output with the addition of a fifth coating station on its Explorer coater in Lucerne, Switzerland.
 
“The filling and packing will slow the output of the line. [But] the maximum speed of the machine was not restricted by the film properties of TriStar 120 or 180,” Brunner says.
 
“When a client changes over to a higher-barrier PVDC film, we say they should start with the same recommended forming temperature range of 110° to 125°C. The TriStar 180 needs a 3° to 5°C higher forming temperature than the TriStar Ultra 120,” he says.
 
Heating/forming temperatures for the Aclar 2000 and 3000 were in the 155°C range. Output using the 3000 was reduced from 250 to 180 blisters per minute. Also, while film flatness for the PVdC films before and after forming was very good, the Aclar structures exhibited strong curling. “Aclar sandwiches can help reduce the curling issue, but it remains a tricky film to run,” Brunner says.
 
LIDSTOCK PERFORMANCE
In lidding materials, Winpak Heat Seal Packaging Inc. (Winnipeg, Canada) offers its Universal Seal extrusion-based technology as an alternative to lacquered substrates for sealing to the formed web.
 
The Universal Seal resin extruded to the structure’s contact surface supports wider sealing windows when compared with traditional lacquered substrates. Bond strengths are achieved at lower temperatures and dwell times.
The application of less heat protects temperature-sensitive products and supports faster run rates, Winpak says.
 
In addition, extrusion-coated foils, foil-based structures, and paper adhere to all commercial blister films including Aclar, when Aclar is used as the contact layer in an Aclar-In configuration. The technology opens the door for packagers to evaluate base web materials other than PVC, says Bill Sharpless, business development manager, Winpak.
 
“Pharmaceutical companies are showing a fairly high degree of interest in introducing alternate thermoformable materials in an attempt to provide a more sustainable product.
 
“The biggest challenge to date has been getting the lidding materials to stick. When you move away from PVC, you get performance issues on the adhesion,” Sharpless says.
 
“We have had superior success adhering to PP, PET, PETG, APET, and PVC. Companies are looking at PP/COC/PP structures for the sustainability advantages.
 
For sealing to Aclar, “we are producing bond strengths equal to or better than [other Aclar-In substrates on the market],” Sharpless says.
 
The technology is also promising for medical device packagers using barrier lidding structures that are sealed to materials such as PP and APET, he adds.
 
Winpak provides Reynolds Packaging materials in the same formulations, and products including the Drug-Pak and Safety-Pak Plus lid stocks, after buying the licensing rights to all Reynolds pharma products last year.
The Safety-Pak Plus PET/foil structure supports lower temperature and higher-speed sealing by eliminating the traditional CR lidding paper layer. Universal Seal can be applied in place of a heat seal coating, Sharpless says.

 

“Winpak is providing the same exact Reynolds product. Customers need only submit changes to the supplier name, manufacturing site, and DMF reference number, and do the stability on the first production run for the annual update to FDA,” Sharpless says.
 

 

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