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German medical products maker bags new IV material

Serum-Werk Bernburg introduces IV bags for hospital use in a new structure that eliminates the need for an overwrap. New hf/f/s machines at a new plant fill medical solutions into the bags.
FILED IN:  Sustainability  > Strategy
An unusual hf/f/s machine (above) is shown running at the  equipment supplier?s facility. The machine was scheduled for shipmentAn unusual hf/f/s machine (above) is shown running at the  equipment supplier?s facility. The machine was scheduled for shipmentIV bags can contain either one or two (above) ports for hospital use

As this magazine went to press Serum-Werk Bernburg AG began filling intravenous medical solutions into a new plastic bag structure. The Bernburg Germany-based maker of human and veterinary medical products is reportedly the first company worldwide to use a material called Propyflex® in rollstock form for IV bags used by hospitals.

Propyflex was developed by Sengewald Verpackungen GmbH in Halle Germany. Sengewald is owned by Pactiv Inc.(Lake Forest IL). Typically companies buy pre-made bags of Propyflex. Packaging World is told there are no U.S.-based users of the material yet.

The 200-micron (8-mil) Propyflex film is a three-layer coextrusion containing an outer layer of pharmaceutical-grade homopolymer polypropylene/a blend of PP and styrene ethylene butadiene and styrene (SEBS)/a blend of PP and SEBS. Sengewald began manufacturing Propyflex in May using new equipment that it prefers not to identify.

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To make the Propyflex IV bags Serum-Werk constructed a new facility equipped with two new horizontal form/fill/seal machines. The Model FFS 773 hf/f/s machines come from Plumat Maschinenbau Espelkamp Germany represented in the U.S. by Plumat North America (Naperville IL).

According to Plumat Serum-Werk is the first company to use this particular model which produces Propyflex bags from rolls of tubular film rather than more conventional flat film. The machines were scheduled for delivery in late December to Serum-Werk's new 1 sq m (5 sq') Bernburg plant.

One machine produces IV bags with a single tube port; the other bags with two ports. Serum-Werk will fill the bags primarily with saline glucose electrolytes and more complex solutions. Hospitals can use one port to deliver the solution to the patient while a second port can be used by medical personnel to infuse drugs into the solution. Initially Serum-Werk will sell the bags to hospitals in Germany.

The machines will form fill and seal the Propyflex material into four different bag/product sizes: a 5.3" x 5.9" bag for 250 mL of solution; a 5.3" x 7.9" bag for 500 mL; a 5.3" x 11.4" for 1-L; and a 7.9" x 11.8" bag for a 2-L size.

The bags will be used for 25 different medical liquids according to Bernhard Schmuck managing director for Human Products at Serum-Werk. With the assistance of an interpreter Schmuck discussed the project with PW after we learned of this application at Pack Expo in Chicago in November.

Multiple advantages

"Using the Propyflex bag is a strategy that focuses on getting new business" says Schmuck. "Each machine has the capacity to produce three million bags a year if we run one eight-hour shift five days a week. So that's six million bags for the two machines. Realistically though we expect to sell two-and-a-half to three million bags in our first year." Schmuck anticipates volume will be strong enough in the near future to make in-house form/fill/sealing more cost-effective than having an outside firm fill pre-made bags.


Propyflex bags have several attributes that benefit Serum-Werk. For one the coextruded bags are clear much like the soft polyvinyl chloride bags Serum-Werk and other IV bagmakers sell. They also function like traditional bags and include a hanger hole. But they don't use plasticizers that make soft PVC bags flexible. According to Sengewald plasticizers could potentially migrate into the medical solution. Also the material in the Propyflex structure doesn't carry PVC's perceived environmental disadvantages.

The new structure also protects against water vapor loss which is the key barrier concern for these IV solutions. "Without the proper barrier the bags could lose water and become unsellable" Schmuck says. To prevent evaporation from its PVC bags Serum-Werk overwraps the filled bags reportedly with PP. With the Propyflex structure the overwrap is unnecessary.

By eliminating the overwrap he says the company saves about 10 Pfennig/bag which is about 6¢US. Those savings help make the Propyflex material less costly than the PVC/PE combination. "The new structure is more economical" confirms Schmuck.

The managing director points out that the decision to use Propyflex was made to add to the company's sales of IV solutions which it fills not only into PVC bags but also in glass and plastic bottles containers that are common in Germany. Schmuck intimates that Serum-Werk wanted to build its sales of these products in plastics though preferrably not in PVC.

Before selecting Propyflex Serum-Werk investigated other bag alternatives but considered those either too rigid to collapse well or too difficult to see through. The company also believes the new bags empty the solutions more easily than other non-PVC alternatives that Serum-Werk considered.

"Propyflex is transparent and a hospital worker can look at the bag and immediately see how much fluid is in the bag or if anything is wrong with the contents" says Schmuck. "Another important advantage is that the bag collapses well making it easy to discard."


Sengewald ships rollstock of film in lay-flat tubular form to Serum-Werk in both 5.3" and 7.8" widths. Both L-shaped Plumat machines operate in much the same fashion. Each hf/f/s machine produces three bags at a time in three parallel lanes. A frame holds three separate stands for three rolls of film. The film is electric motor-driven in a horizontal plane parallel to the floor. Film is driven past a printing station where a hot-foil stamper imprints the name of the solution usage instructions and a number that indicates the solution is approved by the German government.

Next film passes by a welding station that heat-seals two areas across the web. The first or leading area that's sealed becomes the top of the bag. The trailing sealed area is the bottom. While the seal is made completely across the bottom a small area is left unsealed at the top to accommodate the insertion of a tube (or two tubes) downstream. As the material is sealed a small hanger hole is also punched out of the film. Next the material is cut along the seal creating an individual bag.

Grippers take the bag which is opened by both a mechanical device and vacuum. Each bag passes through a transfer station where it continues at a right angle through the rest of the f/f/s process. This section of the machine includes a racetrack-like conveyor to which are mounted numerous "holding pins." Pins are mounted in sets of two to accommodate bags with either one or two tubes.

As the racetrack moves tubes are positioned onto these pins. Sengewald says the tubes are made by a third party under a licensing arrangement with Sengewald. The coextruded tubes come in rollstock. The material combines an inner layer of ethylene vinyl acetate and an outer layer identified only as a special blend of PP and elastomer.

At a station next to the racetrack the tube material is cut into the appropriate length then fed onto each pin. The bag samples PW received had tubes measuring about 21/4" L. The opening at the top of each bag is placed onto the pair of tube-carrying pins. The tube (or tubes) is then heat-sealed in the bag. In our samples about 5/8" of the tube is sealed in the bag. Six tubes are sealed to six bags simultaneously.

The Plumat machine that inserts two tubes for each bag uses a second tube sealing station.

After tubes are sealed into the bags grippers deliver the bags to filling stations. Three bags are filled at a time at two stations. The first station fills half the solution into the bags which are then indexed to a second station for the final 50% of the fill. Filling in two steps speeds the process according to Plumat. After filling the tube is closed off with the application of a polycarbonate/rubber stopper.

Grippers release the bags onto a conveyor where they're placed in trays for autoclave sterilization. Sterilized bags are subsequently removed from trays by a robotic system before they're case-packed palletized stretch-wrapped and warehoused. Bags are sold to and stored by hospitals at ambient temperatures and can be held for up to two years about the same as the PVC/PE bags.

Worth the investment

The new plant two new hf/f/s lines and new film structure represent a serious investment by Serum-Werk. How does the company justify the financial outlay? When pressed Schmuck responds "it's a complicated question to answer. We did it for market reasons. These bags give us a good way to compete with bottles and provide an alternative for PVC bags."

It is believed that some of the risk taken by the company was offset by financial assistance from the government. A Sengewald representative says this financial aid helps stimulate new investments in the former East Germany.

To date Serum-Werk "has shown the new bag at different exhibitions and sales meetings and the feedback we've received from the market has been positive" says Schmuck. He indicates that some customers have said they will likely switch from bottles or PVC bags to this structure as it becomes available. While Schmuck doesn't want the Propyflex bags to cannibalize current PVC bag sales he's aware that environmental concerns may eventually result in the new structure replacing PVC bags.

Currently Serum-Werk is working to sell the bags not only in its home country but also in Holland Belgium Scandanavian countries Vietnam and others.

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