Description of Liquid Silicone Rubber
MC RTV silicone rubber is a two component elastomeric cross-linking at room temperature. The polymerization can be accelerated by heat (max. 150 C). The silicone components are delivered as liquids, which once mixed and cured transform into a transparent, elastic and resistant material. Polymerization occurs without formation of heat.
Advantages of Liquid Silicone Rubber
1. Easy Curing: MCPLA-H40 polymerizes at room temperature (23C). The curing characteristics is independent of part thickness.
2. High Transparency
3. High tear and tensile strength
4. Long shelf life with low shrinkage
Applications of Liquid Silicone Rubber
Label manufacturing, Molding applications requiring low shrinkage, such as toys, jewelers, automotive, rapid prototyping etc.
Data sheet
| Item No. |
MCPLA-H40 |
| Appearance |
Clear |
| Viscosity(cps) Part A |
40000-50000 |
| Mix ratio(by weight) |
10:1 |
| Pot Life(mins) |
90-120 |
| Curing Time(hrs) |
24 |
| Hardness(shore A) |
38-39 |
| Tensile Strength(Mpa) |
5.3 |
| Tearing Strength(KN/M) |
23 |
| Elongation(%) |
>355 |
| Shrinkage(%) |
0.10 |
Instructions for making silicone molds
1. Mixing the two components
According the mixing ratio 10: 1 weighting part A and B, the two components may be thoroughly mixed by hand or using a low speed electric to minimize the entrance of air and to avoid any temperature increase.
Note: It is also possible to use a special mixing and dispensing machine for the two silicone components, further information is available upon request.
2. Molding
The mixture should be degassed preferably at 30 to 50 mbar to eliminate any entrapped air. If a dispensing machine is used, the two components are degassed separately prior to mixing. The silicone mixture expands to 3 to 4 times of its initial volume and bubbles rise to the surface. The bubbles progressively disappear and the mixture returns to its initial volume after 5 to 10 minutes. Wait a few minutes to complete the degassing and then flash the vacuum. The silicone is ready for pouring, by gravity or under low pressure.
Note: Flashing the vacuum once or twice accelerates the degassing. It is recommended to use a container with a high diameter/height ratio(3 to 4 times of the initial volume)
3. Polymerization
The curing may be slowed down at lower temperature or accelerated by applying heat.
Note: In general contact with certain materials can inhibit the cross linking of RTV.
Natural rubbers vulcanized with sulfur
RTV elastomeric is catalyzed with metal salts, e. G. Tin compounds
PVC stabilized with tin salts and additives
Epoxy catalyzed with amines
Certain organic solvents, such as Ketones, alcohols etc.
In case of doubt, it is recommended to test the substrate by applying a small quantity of the mixed silicone on a restricted area.
Storage and shelf life of Liquid Silicone Rubber
MC silicone RTV must be used within 12 months from the manufacturing date. Beyond this date, MC silicone no longer guarantees the products confirms with the sales specification. In order to preserve best properties it is recommended to follow strictly the following guidelines:
Store the original packing tightly sealed and at a temperature below 30 C
Use the product as soon as the packaging has been opened.
Packaging of Liquid Silicone Rubber
Part A: 20kg/drum; Part B: 2 kg /drum
Special containers are available are on request.
