Properties of non-vulcanized RTV silicone mold rubbers
| RTV 710 | RTV 725 | |
| Color | White | White |
| Viskosity (Brookfield, cps), ±5000 | 20.000 | 25.000 |
| Specific gravity | 1,25 | 1,25 |
Properties of vulcanized RTV silicone mold rubbers
(2% with Catalyst CX catalyst, after 4 days, 23oC / 50% relative humidity)
| RTV 710 | RTV 725 | |
| Hardness, Shore A (± 2) | 10 | 25 |
| Tensile Strength, Mpa (± 2) | 4 | 4 |
| Tear Strength, KN/mm (± 2) | 35 | 27 |
| Flexibility, % (± 50) | 480 | 480 |
The general purpose Catalyst CX is used for the vulcanization of RTV 7xx series silicone mold rubbers.
| CATALYST | Catalyst CX |
| APPEARANGE | Transparent |
| DENSITY | 0,96 |
| MIXING RATIO (By weight) | 2,0 – 2,5 % |
| SPILL TIME | 40 – 60 Minutes |
| VULCANIZATION DURATION | 6 – 8 Hours |
RTV 2 is the abbreviation of 2 Chemical Componented Room Temprature Vulcanizing, which has become the standard in the world.
A two-component mixture (Base and curative; A + B), very soft to medium hardness is a type of silicone rubber. RTV silicon is used as the first of these components, the second component is a catalyst consisting of a tin compound such as platinum or dibutyltin dilaurate.
RTV2 Silicone rubbers are applied by pouring and dipping techniques according to product type and application area. After mixing the silicone rubber material with the appropriate catalyst, it is applied with one of these techniques, pot life. The post-freezing mold is ready for new copy production.
Flexible and easy operation Linear draw ratio of less than 1%.
RTV2 The mold material prepared by mixing the silicone rubber with a catalyst freezes (vulcanized) at room temperature (min. 10 ° C up to 70 ° C) over a period of time. Freezing time varies between 2-24 hours according to the catalyst used..
Linear draw ratio of less than 0.1%.
RTV2 Silicone rubber with its own special catalyst prepared by mixing the mold material at room temperature (10 ° C up to 70 ° C) for a long period of time between freezing (up to 150 degrees and with the most direct heating) freezes in a very short time (vulcanized). The mold material obtained is less flexible than the types of condensation and is preferred for the production of molds and industrial materials..
Most important part of the mold making studies is the preparation of the model and the mold. The details of the model to be taken should be cleared and the impurities such as oil dust should be cleaned. It is recommended to use mold release agent considering the possibility of the silicone sticking to the model. When the mold is taken from the models such as concrete, porous and absorbent surfaces, mold protection product must be used and the model is prepared and placed in the support mold in the most appropriate way.
After the silicone rubber package has been opened and thoroughly mixed, the desired amount should be taken and placed in a clean container and the lid of the package should never be left open. Silicone rubber and catalyst ratios are measured by weight and mixed thoroughly.
After the rubber has been mixed with the catalyst, it should be mixed homogeneously with a clean spatula. The catalyst must be completely filled with silicone. When mechanical mixture is applied (with mixer), 2 cycles of 20 seconds will be sufficient.
The air is vacuumed by placing the container in a desiccator during the mixing process and to avoid air bubbles as a result of the reaction. During this process, the silicone volume can be swollen up to 5 times. Caution should be paid to the overhang of the captain during the vacuuming is recommended to be over 2 bar pressure and 15 minutes is recommended to exceed.
In order to prevent the formation of air bubbles during casting, the silicone must be poured at a single point in the top of the model and at constant speed. It is recommended to apply a thin layer with brush first in the Incomplete and Complicated models. The resulting air bubbles are removed by compressed air and after 5 minutes the entire silicone is poured onto the model.
Two-component mold silicones are of two types with condensation freezing and filling. The condensation-freezed silicones freeze at room temperature for 6 to 15 hours. The Additive silicone vulcanizine silicones for 24 hours at room temperature, but it is possible to shorten the heat-freezing time.
The support molds are removed after the silicone has been frozen in the specified time. The silicone mold should be removed from the model without using sharp and sharp tools. After leaving the model, it is recommended to leave the silicone mold in the open area for 2-3 hours at room temperature. Silicone molds that are rested outdoors have more casting and molds last longer.