Soft Elastic News 08/2019 | Thermoplastic elastomers
Thermoplastic elastomers of ACTEGA DS are used in medical technology and in pharmaceutical applications as well as in the consumer goods area.
To generate an adhesion, there are different bonding types, mechanical, chemical and physical. In a bonding compound in e.g. the diffusion model, a soft component overmolds the surface of the hard component which softens enabling diffusion of the molecules in the boundary layer. This is responsible for the quality of such a bond. Important in this procedure is that both phases are geared to each other and the wettability of the surface of the thermoplastic.
One alternative is to specifically apply the sealing element by means of injection-molding. In a single manufacturing step – injection of the hard component followed by the soft component – a substance-to-substance compound can be created between the soft elastic seal and the hard component. Accompanied by mechanical strain and media impact, this bonding strength which is achievable by adhesion-compatible plastic combinations is of particular importance as it is also subject to various influential factors, including the polarity of the join partners, the surface structure and quality, and the basic chemical structure of the plastic. As materials such as PC and ABS have not proved ideal in terms of adhesion for soft elastic materials such as TPE, specific tests were conducted to modify this TPE with the aim of optimizing adhesion to these plastics in particular. At the same time, they also need to comply with the respective medical regulations and guidelines prevailing as regards biocompatibility, toxicity, and patient safety in this sensitive industry. The adhesion-optimized variants of the PROVAMED® TPE portfolio meet the core requirements on optics, high strength in combination with PC and ABS, and biocompatibility in accordance with ISO 10993.