SEMICOSIL® 914 is a shear-thinning, addition-curing, 2-part silicone rubber that cures to a soft silicone gel when mixed with ELASTOSIL® CAT PT, ELASTOSIL® CAT PT-F or ELASTOSIL® CAT UV.
All surfaces must be clean and free of contaminants that will inhibit the cure of SEMICOSIL® 914.
Examples of inhibiting contaminants are sulfur containing materials, plasticizers, urethanes, amine containing materials and organometallic compounds – especially organotin compounds.
If a substrate’s ability to inhibit cure is unknown, a small-scale test should be run to determine compatibility.
SEMICOSIL® 914 contains the crosslinker, ELASTOSIL® CAT PT, PT-F and CAT UV contain the catalyst. Even traces of the platinum catalyst may cause gelling of the component containing the crosslinker. Therefore tools (spatula, stirrers, etc.) used for handling the catalyst-containing component or the catalyzed compound must not come into contact with this component.
The two components should be thoroughly mixed at a 10 : 1 ratio by weight or volume.
To eliminate any air introduced during dispensing or trapped under components or devices a vacuum encapsulation is recommended.
The system SEMICOSIL® 914 / ELASTOSIL® CAT UV (10:1) is activated by direct UV irradiation. UV irradiation should use emissions in the wavelength range between 250 and 350 nm.
Typically D-bulbs (Fe-doped Hg-light sources) using ozone-free quartz should be used and are commercially available. H-bulbs with emissions below 250 nm are not recommended.
Curing time of the UV-active system SEMICOSIL® 914 / ELASTOSIL® CAT UV (10:1) is highly dependent both on the intensity and dose of the UV-light and the spectral intensity distribution. The curing is also dependent on the layer thickness, the optical properties of the substrate and temperature. Increase of the temperature will fasten curing reaction.
SEMICOSIL® 914 / ELASTOSIL® CAT UV (10:1) will only cure in directly irradiated areas.
Curing of SEMICOSIL® 914 catalyzed with ELASTOSIL® CAT PT or ELASTOSIL® CAT PT-F (10:1) is possible at ambient temperature (ca. 23°C) and is promoted by elevated temperature.
For fast cure a vented oven can be used.