The BFS technology – Blow-Fill-Seal – is mainly used in the pharmaceutical industry where there is a need for sterile, particle-free packaging in pharmaceutical solutions. Pharmaceuticals that may be concerned are, for example, injectable solutions, antibiotics, eye drops, perfusion solutions for dialysis, solutions for drainage, solutions for aerosol therapy and solutions for hemofiltration. In addition to these main fields of application, this technology is also used for the packaging of fresh fruit juices, non-carbonated beverages, milk and various cosmetic products, including creams.
During the production process, a small amount of plastic is injected as the mold is closed during the formation of the parison, so as to form the container. This addition constitutes a plastic waste, which is then cut at the end of the process and transported out of the cleanroom.
A criterion for the choice of this technology is the cost of primary packaging, and therefore the control of the process. See below some key points that are characteristic of this technology.
Why is the weight of the container an important criterion?
Economic consideration
The price of plastic varies from country to country and over time, and may also be subject to customs duties. In some countries, if the plastic or its raw material is imported, the price will also depend on exchange rates. However, in general, the price of pharmaceutical grade polypropylene (PP) or polyethylene (PE) can vary from 1,700€ to 2,000€ per tonne. It is therefore an important economic component of the final price of the container.
For example, if a standard BFS SYFPAC® machine (Fig.1) can make 10 million 500 ml bottles per year (for which the empty weight is approximately 16 grams, and that of the waste, approximately 7 grams), the theoretical annual consumption of polymer would be approximately 230 tons, broken down into 160 tons of bottles and 70 tons of waste. However, it is interesting to note that the plastic used for the pharmaceutical industry maintains a certain value as virgin plastic because it is considered cleaner than the waste generated by other industries. Generally, between 60 and 80% of the original price may be obtained. So if the average price of virgin plastic granules is 1,700€ per tonne, one can expect to spend around 390,000€ for plastic granules in order to make 10 million bottles a year.
It is clear in the example above that the weight of the container is an important economic criterion.
Environmental consideration
The second reason is related to ecological consideration. Reducing the weight of the container itself by reducing the use of materials and therefore the extrusion energy as well as the associated transport is a key factor of impact reduction. Indeed, the more the forming technology will be controlled, the more the thickness of the container will be adapted and the consumption of raw materials. Thus, the energy used for the extrusion will also be adjusted.
Secondly, the ability to recycle plastic waste ensuring its valuing in the same process or another application resides at the second stage of carbon footprint reduction of the packaging process.
Factors determining the weight of a container and the weight of the plastic waste
- Permeability of the plastic
The plastic is permeable to gas (oxygen, carbon dioxide) and steam that can alter the finished product. The stability of a container is highly dependent on its permeability. The more permeable the material is, the more the wall thickness required to achieve a comparable stability will be increased.
The permeability of PE is twice as important as that of low density polyethylene (LDPE). So if we compare PP and LDPE, PP bottles can be thinner, but they cannot always offer great stability. A process that can easily accept different materials will increase production flexibility.
- Physical strength of plastic bottles
Blow molding is a suitable process and can produce either very thin or very thick bottles. However, the question of its strength must arise during its steam sterilisation – a process placing the container under external and internal pressure, a typical internal pressure in the bottle during sterilisation at 121 ° C will be between 1.25 and 1.7 bar – and its resistance during transportation.
So the question is not to know the minimum thickness of the bottle that can be achieved, but what should the optimal thickness be, depending on the use. The strength of polypropylene is greater than that of LD polyethylene, meaning bottles can be made in PP whilst being a container that can withstand stresses during sterilisation and transportation.
- Bottle shape
With round bottles, it is possible to significantly reduce the thickness while with oval bottles it is not be possible to reduce the thickness to the same extent. The bottles with necks (Euro Head bottles have a collar with no neck ) tend to have a greater thickness in the region of the neck, whereas the bottles with ejectors do not have this limitation.
BFS Advanced Technology
Most large BFS machine brands today have a sophisticated control system for the thickness of the wall, even sometimes capable of controlling the thickness at over 300 points (Figure 2), and therefore a capacity to reduce the thickness of the wall to less than 0.15 mm (for 500 ml bottles). Thus these modern machines have the ability to considerably reduce the weight of the container.
The polymeric material is subjected to thermal and physical stress during the blowing extrusion process. Such stress slightly deteriorates the quality of the polymer at each further passage in the extruder. To control the progressive deterioration of the polymer quality with each passage through the extruder, a number of uses must be approved, after which all waste must be discarded and a new cycle should be started with native virgin polymer. The use of latest generation BFS machines with advanced temperature control improves the reduction of the stress to which the polymer material is subjected at each passage through the extruder.
It is therefore clear from the foregoing that the latest generation of machines are able to make very fine containers and reduce their weight, but the question today should be whether such a thin vial can resist all processes and subsequent handling, and if such a thin wall remains stable for more than five years.
Above are the main factors that help determine the weight of the bottle and not the capacity or limit of the blowing or casting process or even the filling ability, because todays technology is optimised to achieve a significant reduction in the weight of the bottles.
What to do with the plastic waste generated during production
- The plastic waste generated can be sold for the production of other elements as explained here-above, valued between 60% and 80% of the initial value due to the cleanliness of the process.
- Sometimes companies mix the waste with other materials and cap molds or medical product container bottle lids and use as secondary packaging.
- Finally, the waste can be cut into small pieces and reused for the same process in mixing with native materials. A check of the legislation, however, is necessary in advance of adopting that use.
What happens to the plastic waste generated by the pharmaceutical industry? In general, the bottles containing very powerful drug residues, antibiotics or cytotoxic substances should not be recycled in order to avoid cross contamination, and these bottles should be disposed of by incineration.
References:
- ISO 13408-1 Aseptic processing of health care products – Part 1: General requirements. Usually, a modern BFS machine should include a protective barrier around the area where the parison is open
- The FDA recommendation on aseptic operations in BFS form the following recommendation “Air in the critical area should meet Class 100 microbiological standards during operations” and states that “A well-designed BFS system should also normally achieve Class 100 (ISO 4.8) airborne particle levels “.(Food and Drug Administration, 2004)
- The Manufacture of Sterile Pharmaceuticals and Liquid Medical Using Blow/Fill/Seal Technology in The Pharmaceutical Blow/Fill/Seal – International Operators Association (BFSIOA) March 2012
TECHNO FOCUS
At the last A3P conference, one question that came up was regarding the notion of particulate control in the immediate vicinity of BFS filling (open parison). In addition to the existing particulate control aspect that can be done online so as to maintain the validated ISO Class 4.8 state and meet the requirements of aseptic processes, here we show a design example aiming to prevent the generation of particles in this particularly critical area.
Indeed, as shown in Figure 2, the nozzles ensure the filling of the container is carried out on the inner sides in order to prevent any foaming of the liquid. Only the perfect nozzle adjustment “tube in tube” (allowing the filling of the formulation and the air extraction at the same time) to the neck of the container makes this possible. This avoids the need for the nozzles to enter the container by below to carry out the filling and ensure that the solution doesn’t foam, because in this case, a series of precautions should be taken to overcome this intrusion such as sterilisation of the nozzles moving part penetrating the sterile barrier of the container. The second major advantage is to completely prevent the back and forth movement generating a risk of particle emission.
INNOVATION FOCUS
The latest generation of BFS machines can now offer innovative container developments perfectly adapted to different formulations as shown by the following examples