May 12 2014
Silastic® FL 40-9201 F-LSR is a two-component, pigmentable fluorosilicone soft paste. It is specially engineered for liquid injection molding. On heating, it is cured to a 40 durometer material. The cured rubber material shows resistance to a myriad of chemicals and solvents over a temperature range of -63°C to +175°C in immersion conditions, and up to +225°C under dry heat conditions.
Applications of Silastic® FL 40-9201 F-LSR
Silastic® FL 40-9201 F-LSR is neither validated nor represented as suitable for pharmaceutical and medical purposes. The following are the applications of Silastic® FL 40-9201 F-LSR:
- Chemical environments and industrial applications
- Complex components with close tolerances
- Solvent and chemically resistant molded components
- Electrical/electronic connectors
- Extrusion onto wires, belts, fabrics, and other surfaces
- Thin, high-precision coatings
Typical Properties of Silastic® FL 40-9201 F-LSR
The typical properties of Silastic® FL 40-9201 F-LSR are listed in the following table:
|
CTM1
|
ASTM2
|
Property
|
Unit
|
Value
|
| |
|
Color Part A |
|
Straw Yellow |
| |
|
Color Part B |
|
Translucent |
| 0364 |
|
Extrusion Rate |
g/min |
10-40 |
| |
|
As Molded3 |
|
|
| |
D792 |
Specific gravity |
|
1.438 |
| |
D2240 |
Hardness |
Shore A |
35-45 |
| |
D412 Die C |
Tensile strength |
MPa
psi |
8.3 min
1200 min |
| |
D412 Die C |
Elongation at break |
% |
300 min |
| |
D642 Die B |
Tear strength |
kN/m
ppi |
17.5 min
100 min |
| |
D263 |
Bashore resilience |
% |
12-22 |
| |
D385 Method B |
Compression set after 22 hours at 177°C (351°F) |
% |
30max |
| |
D471 |
Fluid resistance - Volume swell |
% |
|
| |
|
Dexron III, 24 hours at 150°C |
% |
1.0 |
| |
|
5W30 Motor Oil, 24 hours at 150°C |
% |
1.5 |
| |
|
IRM 903, 24 hours at 23°C |
% |
3.0 |
| |
|
Reference Fuel C, 24 hours at 23°C |
% |
20.3 |
| |
|
Reference Fuel B, 24 hours at 23°C |
% |
17.0 |
1Materials were tested according to Dow Corning Corporate Test Methods, which in most cases are similar to the ASTM standard listed above. Copies of CTMs are available on request.
2ASTM: American Society for Testing and Materials.
3Cure conditions: molded 10 minutes at 177°C (350°F); post-cured 4 hours at 200°C (392°F).
Key Features of Silastic® FL 40-9201 F-LSR
The following are the key features of Silastic® FL 40-9201 F-LSR:
- Two-component product with convenient 1:1 mix ratio
- Rapid cure at elevated temperatures
- Free from solvents (100 percent solids)
- Stable over a broad temperature range
- Good tensile and tear strengths for better performance
- High temperature mold release
- Superior resistance to fuel, oils, solvents and chemicals
Mixing and De-airing of Silastic® FL 40-9201 F-LSR
The two-component Silastic® FL 40-9201 F-LSR is offered as parts A and B, of which Part A is straw yellow and Part B is translucent to facilitate identification and monitoring of the mix. These parts need to be mixed in a 1:1 ratio. Silastic® FL 40-9201 F-LSR can be applied by:
- Injection molding equipment
- Extrusion coating onto a substrate
- Hand brushing onto a surface
For production, it is recommended to use meter mix equipment to pump, meter and mix the two parts without introducing air. De-gassing the mixture needs to be done under vacuum to avoid the entrapment of air bubbles.
Pot Life of Silastic® FL 40-9201 F-LSR
After mixing the two parts, the usable life of Silastic® FL 40-9201 F-LSR will extend for at least 96h at room temperature. The usable life after mixing can be extended considerably by refrigerating at low temperatures. The usable life of Silastic® FL 40-9201 F-LSR is 12 months from the date of manufacture when stored in the original unopened containers at or below 32°C. This product is offered in lot matched pail (22kg and 22kg) and drum kits (205kg and 205kg).
Cure Rate
Heating Silastic® FL 40-9201 F-LSR to 150°C cures it within seconds. The cure time for a specific component is the time required to bring the part to this temperature. The cure time for Silastic® FL 40-9201 F-LSR is a function of cure temperature and the dimensions of the component being cured. The cure cycle ranges between 20 and 90s for injection molding of parts under 10g at a cure temperature of 200°C. Determining curve level by running a MDR curve at the desired molding temperature yields optimum results.
Cure Inhibition and Clean-Up/Removal
The avoidance of contamination is important as the presence of tin complexes, sulfur, amines and some peroxides can inhibit the cure mechanism of t Silastic® FL 40-9201 F-LSR. The uncured product can be cleaned up using solvents like Dow Corning® OS Fluids, xyline, toluene, naphtha, and mineral spirits. Cleaning can also be done with IPA, but it is less effective.
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This information has been sourced, reviewed and adapted from materials provided by Dow Corning Automotive.
For more information on this source, please visit Dow Corning Automotive.