ZC20 Mould Making Silicone, Shore A 21
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ZC 20 is a poly-condensation RTV 2 silicon rubber that vulcanises at room temperature. Shore A hardness: 21.
1. Description and Main Features
ZC 20 is a poly-condensation RTV 2 silicon rubber that vulcanises at room temperature.
2. Main applications
Industrial (low dimensional variation, high mechanical resistance, long life of the mould).
3. Instructions for Use
Take the two components (BASE and CURING AGENT) and shake before use in order to homogenize each component prior to mixing. The BASE component is white, whereas the CURING AGENT component is transparent/ yellowish.
Please keep in mind that the exact proportions should be 100:5 (5 units of curing agent for every 100 units of base). For example, given 1Kg of base, you must add 50g of curing agent. This ratio must be respected in order to ensure the final characteristics of the product. DO NOT exceed the recommended ratio for the curing agent. It is possible to use LESS curing agent (3-4%) than the recommended ratio (5%), however keep in mind that although dimensional variation will be lower, setting time will increase.
Hardness is reached after a certain number of hours and if the correct % of catalyst is respected. After 24 h the product is polymerized. After 72 hours, perfectly hardened. Attention: the condensation bases naturally accelerate near the expiry date; therefore, it is recommended to use, in this case, less catalyst so that the product improves in flexibility and release properties.
It is also recommended to homogenise the base individually and also the curing agent for possible sedimentation before use.
Mix thoroughly until the mixture white color is homogeneous. Once the product is perfectly mixed, it is ready to be casted and we recommend pouring the silicone from a 30 cm height into the mould.
Complete hardening requires about 72 hours after mixing the two components. However, the product can be demolded in as short as 18-24 hours time.
Effects of temperature on setting and working times: The working time and setting time are reduced if the temperature exceeds 23°C (e.g. if the temperature is 40°C, the working time and setting time are approximately cut in half). If the temperature is less than 23°C, the working time and setting time increase considerably.
Cured silicone properties are guaranteed within temperatures ranging from a minimum temperature of - 40 °C to a maximum temperature of +200°C.
4. Chemical and Physical Properties
- Working time at 23 ºC: less than 50 min
- Hardness after 24 h at 23 ºC: 19 Shore A
- Hardness after 72 h at 23 ºC: 21 Shore A
- Tear strength: 19 N/m
- Tensile strength: 3 MPa
- Elongation at break: 270%
- Dimensional variation after 48 h: 0,33%
- Viscosity: less than 50.000 cP
- Density: 1,21 g/cm3
- Mixing ratio by weight = 100:5
5. Shelf Life
12 months if stocked between 5° - 27°C (41° - 80°F) in sealed containers away from direct sun light.
Type of supply
ZC 20 mould making silicone x 1 kg, supplied with 50 g of ZC 120 Non Flammable curing agent
ZC 20 mould making silicone x 5 kg, supplied with 250 g of ZC 120 Non Flammable curing agent
ZC 20 mould making silicone x 20 kg, supplied with 1 kg of ZC 120 Non Flammable curing agent