TPE   Actega  

Sterilizable, adhesive, conformant - The right property for any application

Thermoplastic elastomers (TPE) are gaining ground, particularly in markets and for applications which are characterized by a variety of regulations and specifications and when it comes to realizing efficient and feasible solutions. And TPE are also increasingly asserting themselves as alternative for rubber, silicone or PVC, not only on account of their property profile, but also by continually optimizing their mechanical, haptic, migration or even performance characteristics – as indicated by the following examples:

In medical technology and pharmaceuticals in particular, sterilizability is an elementary factor. Even the raw materials must be sterilizable when developing new products and packaging for these markets. This applies for all conventional sterilization methods. This requires the following properties:

Ethylene oxide sterilization is a low-temperature method which kills microorganisms at 10 °C by forming a compound with the protein molecules and destroying them. As the sterilization time depends on the temperature – the higher the temperature, the shorter the sterilization time – a temperature range of 37 to 60 °C is usually applied. Combined with a low process temperature, this method is suitable for many thermoplastic materials and is applied in particular for disposable items such as syringes, compresses, swabs and medical products which are sensitive to temperature.

Sterilization with hot vapor is at 121 or 134 °C and overpressure of up to three bar in the autoclave. When the vapor condenses on the item to be sterilized, energy is released which damages the microorganisms. Hot vapor sterilization at 134 °C is the most popular method of sterilizing reusable medical products.

High-energy, ionizing gamma irradiation deactivates the microorganisms. When this low-temperature method is applied, the minimum radiation dose must be observed. But not all plastics are suitable for multiple sterilization by gamma rays. Soft PVC for instance is prone to yellowing. But also swift ageing and brittleness are possible results of the gamma irradiation. This method is only applied industrially and almost exclusively for disposable items.

In order to prevent any negative impacts, the material formulae need to be compiled very carefully using stabilizers and other supporting ingredients – as is the case with the PROVAMED® portfolio offered by Actega DS. Extensive tests of the various variants comparing gamma irradiation, autoclaving and gassing with ethylene oxide indicate the resistance displayed by these materials to signs of wear. Tests on PROVAMED® compounds indicate that tensile strength remains virtually unaffected even after irradiation with 50 kGy. The high temperatures in the autoclave can even have a positive effect on the relaxation and crystallization processes of some polymers contained in the TPE recipe. This can increase tensile strength and elongation at break. Similar effects have been detected when gassing with ethylene oxide.

As the demand for hard-soft compounds increases in medical technology accompanied by an increased prevalence of multi-component technology in this area, the demand for soft-elastic plastics with special adhesive properties is also on the up. The quality of a component manufactured using hard/soft technology depends on the bonding strength of the compound. A major role is played in this context by resilient TPE. As a result, housings, lids, connecting pieces, syringe plungers, catheter couplings, and functional components (hard component) can be bonded using seals or plugs (soft component), for example. Media contact and increased temperatures are maintained. Against this background Actega DS included adhesion-optimized variants in the PROVAMED® TPE portfolio. These transparent, soft elastic, adhesion optimized TPE not only display outstanding adhesion to a variety of plastics, including polycarbonate (PC) and acrylonitrile butadiene styrene copolymer (ABS); it also complies with the relevant regulations and guidelines prevailing in this sensitive industry in terms of biocompatibility, toxicity and patient safety. What's more, the adhesive properties have been improved to the extent that they are maintained even at continuous media contact and increased temperatures.

Whether for contact with food, in medical technology and pharmaceuticals, for personal care items, toys or household goods, when plastics are used, it is necessary to observe numerous statutory provisions, directives and regulations, and to maintain limit values. A decisive role can then be played by the right raw materials supplier availing of decades of expertise such as Actega DS, for example: The specialist in the manufacture of TPE synthetic granulate, has extensive expertise when it comes to conformity, regulatory issues, and the observance of limit values. Accordingly, the TPE are also certified for applications which involve contact with food. With an innovative range of TPE materials, care is taken to refrain from using PVC, ensuring sustainable production, resource and energy efficiency, and adherence to all provisions and limit values specified by the EU or the FDA. This also applies for the high demands made of medical grade materials for use in medical technology, pharmaceuticals, and personal care. It concerns tested bio-compatibility and physiological safety in accordance with ISO 10993 and USP Class IV, whereby not only compliance with technical requirements is examined but also how compatible the material is. In accordance with the Medical Products Directive MDD 93/42 EEC, this biological test is always necessary when the patient comes into direct contact with the material/product.

Furthermore, these raw materials must also be conformant with the FDA and be free of heavy metals. They should not contain silicone, latex or phthalates. Chemical and media resistance represent further features. After all, sterilizability of materials is a must in the medical environment.

At Actega DS, extensive research and development management is available from the initial idea and the customers requirement catalog which provides support of each individual step from the initial material approaches through test specimens and test rods, in-house tests, quality control and analytics, as well as technical service on site, until the material has been optimized for the respective requirement profile and all certifications and approvals have been obtained.

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