The best combination ever since the existence of polycarbonate/silicone compound materials

WACKER presents its latest development in silicone elastomers: ELASTOSIL^® LR 3078. Not only does this newly developed liquid silicone rubber feature excellent adhesion to polycarbonate, it also means surfaces no longer need pretreatment. The patented self-adhesive technology opens up unprecedented possibilities in the large-scale production of two-component parts.

Self-Adhesive and Highly Adhesive

Discover the production of hard/soft compound materials made from polycarbonate and the new ELASTOSIL^® LR 3078 liquid silicone rubber. Experience how the combination of these two components withstands even the strongest forces.

New Possibilities in Two-Component Injection Molding

Breathingmask out of two components - silicon and polycarbonat

Fully automated, two-part injection molding processes can be used for making ventilation masks from ELASTOSIL^® LR 3078.

ELASTOSIL^® LR 3078 was especially developed for this kind of industrial processing. Here are the seven most important benefits of our new product range:

Reliable adhesion, without time-consuming pretreatment of the polycarbonate, creates the best conditions for cost-effective mass production of multicomponent parts.
The fact that the liquid silicone rubber only bonds with the hard component and not the mold ensures that the injection-molding machine runs without interruption.
Very low tendency to form deposits in the mold. This enables a fully automatic injection molding process without interruptproduction to dismantle and clean molds.
The fast curing rate of the self-adhesive silicone rubber enables very short cycle times.
The product range also enables high-precision complex structures and caters to the component miniaturization trend.
Because it is a biocompatible and steam-sterilizable material, ELASTOSIL^® LR 078 is perfect for medical applications.
The new self-adhesive technology does not contain any bisphenol A (BPA) as a bonding agent. This boosts safety during production and processing of the silicone rubber while also serving to protect consumers.

The Soft Component is Hard Wearing

The new self-adhesive technology keeps its promise at all levels of hardness, from 20 to 70 Shore A. ELASTOSIL^® LR 3078 impressively demonstrates this in a 90° peel test. In this test, the force needed to peel off the silicone layer at a right angle to the substrate was determined on multicomponent material strips. The peel forces established in these tests were at least 10 newtons per millimeter. What is more, only the soft component tore during peel testing, whereas the bond between the hard and soft components remained intact. This cohesive failure along with the high peel forces clearly shows that ELASTOSIL^® LR 3078 is an excellent self-adhesive.

Crack image from one of the peeling tests

Torn sample from one of the peel tests: Peel testing stressed samples of multicomponent materials to their breaking point. In samples made of ELASTOSIL^® LR 3078 and polycarbonate, it was the soft silicone component which consistently tore. The bond between the hard and soft components remained intact.

Mechanical properties before and after steam sterilization

Peel-force values following injection molding onto a variety of polycarbonate grades: Adhesion of ELASTOSIL^® LR 3078 on three commercially available grades of polycarbonate

134 °C Steam Leaves Elastosil^® LR 3078 Cold

Adhesion Performance on selective polycarbonate grades

Cured rubber made from ELASTOSIL^® LR 3078 is biocompatible, as demonstrated by select tests meeting DIN ISO 10993 and United States Pharmacopeia (USP) Chapter <88> Class VI standards. What is more, polycarbonate/silicone composites made with ELASTOSIL^® LR 3078 can be steam-sterilized, because their mechanical properties remain virtually unchanged even after 100 sterilization cycles involving exposure to steam heated to 134 °C. Adhesion strengths only deteriorate slightly after repeated sterilization. The new liquid silicones are therefore ideal for manufacturing two-component parts for medical devices.