When and where can Thermoplastic Elastomers replace silicone?
KRAIBURG TPE solutions as viable alternatives for bicycle parts, toys, and much more.
Versatile modification options and good recyclability on the one hand, extremely high temperature and media resistance on the other. Nevertheless, there are recurring requests to replace silicone elastomers with TPEs. But is this even practical? Together with KRAIBURG TPE, we provide answers. One such answer is the new NEXT GENERATION Supersoft TPE – for sustainable applications in the soft hardness range of 30 to 50 Shore 00 or 45 to 70 VLRH. Easily processed by injection molding and even 3D printing, Plastoplan Kunststoffe thus offers high-quality KRAIBURG TPE plastics as a recyclable silicone alternative – for bicycle parts, fishing lures, toys, cosmetic packaging, gel or soft pads, and orthoses.
Pros and Cons!
Fundamentally, a comparison between TPEs and silicone rubbers or silicone elastomers is akin to comparing apples and oranges, ultimately revealing few commonalities. While TPEs and silicones are typically soft, elastic materials with similar haptic properties, they differ fundamentally in their chemical composition. TPEs are thermoplastic elastomers, whereas silicones belong to the group of elastomers. This leads to significant differences in processing, technical product properties, sustainability aspects, and ultimately, application areas.
Manufacturing: Costs, Health, and Carbon Footprint
TPEs are materials that combine the properties of elastomers with those of thermoplastics. TPE is soft like rubber but can be plastically deformed by heat, enabling processing via injection molding (including 2-component co-molding) and extrusion. The absence of cross-linking results in several distinct characteristics: modification possibilities, broad processing windows, and suitability for multi-component applications. Furthermore, the thermoplastic processability of TPEs allows for both end-of-use and in-process recyclability, highlighting their sustainability aspect.
In comparison to TPE, a cross-linked material proves superior in certain areas. When high demands are placed on temperature and media resistance or mechanical performance across wide temperature ranges, many silicones exhibit superior properties. TPE, on the other hand, is characterized not only by its high adaptability to diverse application conditions but also by its reversibility. Whether it's flowability, adhesion to other plastics, or hardness/softness, even to supersoft levels: TPEs can be modified with extreme versatility. Materials with high proportions of recycled content or bio-based raw materials (mass balance approach) are also possible.
In contrast, the majority of silicones are irreversibly cross-linked elastomers. While this structure limits modification possibilities, silicones as materials are also often more costly and energy-intensive to produce than TPEs. When comparing greenhouse gas potential, TPEs exhibit a significantly lower carbon footprint (Product Carbon Footprint) than silicones, according to DIN EN ISO 14067. This alone makes them a more sustainable material choice.
Processing: Tooling Effort, Post-treatment, and Adhesion
TPEs offer excellent processability, as they deliver finished parts, literally, directly from the mold, whereas silicone parts usually require storage, tempering, or post-processing after the molding process. Furthermore, silicones exhibit limited adhesion to plastics. Hard/soft two-component applications therefore necessitate an adhesion promoter or adhesive. TPEs, however, depending on their material type, show easy modifiability and, even in direct combination with polar plastics such as polyamides, exhibit excellent and durable adhesion.
Application: Dominances, Overlaps, and Softness
A crucial advantage of cross-linked silicones is their high elasticity across a wide temperature range (up to 250 °C), even under high cyclic mechanical stress. This is attributed to their covalently bonded 3D network, which also renders them highly resistant to chemicals, UV radiation, and weathering. This property profile benefits, for example, elastic baking molds and dosing tubes in the food and chemical industries. TPEs, on the other hand, dominate in a wide array of diverse multi-component applications, ranging from consumer goods to toys and sporting articles.
Due to their distinct USPs, the application areas of the two materials are fundamentally clearly delineated. The few overlapping application areas where alternatives might be considered are currently limited and include, for example, menstrual cups, baby pacifiers, profiles, and medical tubing.
While not a complete convergence, KRAIBURG TPE achieves an approximation with NEXT GENERATION Supersoft TPE, designed for applications in the soft hardness range (VLRH). NEXT GENERATION Supersoft TPE meets exceptionally high demands for softness and is available pre-colored, as well as in translucent and transparent formulations. These super-soft products – with hardness levels ranging from 30 to 50 Shore 00 or 45 to 70 VLRH – are processable by injection molding and even 3D printing. They provide a very pleasant, dry, and skin-like surface haptics, coupled with high elasticity and good media resistance. The application spectrum extends from bicycle parts and fishing lures to toys, cosmetic packaging, gel or soft pads, and orthoses. Find out more in the Fact Sheet.
Recycling: Circular Economy, Post-Consumer and In-Process Recycling, Certification
In contrast to silicone, TPE applications are highly recyclable; certificates from the independent Aachen Institute cyclos-HTP GmbH confirm the co-recyclability of various KRAIBURG TPE products within existing PP and HDPE streams of the recycling industry. Furthermore, KRAIBURG TPE's portfolio already includes many proven, more sustainable alternatives with post-consumer and post-industrial recycled content, thereby addressing the requirements of all target markets, including a material-dependent reduced PCF. For strictly regulated markets where these solutions are not applicable, KRAIBURG TPE has been offering compounds with corresponding ISCC PLUS certification since early 2023. Through mass balancing, customers benefit from a lower PCF with identical processability and technical performance, while also ensuring compliance with regulatory requirements. The certification ensures that the entire supply chain adheres to stringent environmental and social standards. Moreover, compounds with a certifiable ISCC PLUS content are, thanks to the mass balance approach, fully equivalent to their fossil counterparts from a regulatory perspective.
