ELASTOSIL® RT 708

ELASTOSIL® RT 708 is a self-levelling, slightly thixotropic, one-part heat-curing silicone for potting and coating applications. When applied in thin layer, e.g. by silk-screen printing, it also can be used as surface adhesive.

 

Cured ELASTOSIL® RT 708 shows very good adhesion to many substrates and long-term stability against weathering, moisture and UV light. The cured silicone rubber may continuously be exposed to constantly changing climatic conditions, UV radiation and temperatures as high as 230 °C (446 °F) without damage.


Properties

  • High extrusion rate
  • Self-levelling
  • Suitable for silk-screen printing
  • Fast curing at elevated temperature
  • Equipped with an UV-active fluorescent tracer for optimized process control
  • recommended service temperature range: -50 °C to +230 °C

Specific features of ELASTOSIL® RT 708

  • Electrically insulating
  • Heat resistant
  • Low viscosity
  • One-component
  • Self-adhesive
  • Steam resistant
  • Thixotropic
  • UV & weathering-resistant
  • Multipurpose potting and coating grade
  • Surface adhesive
  • Typical fields of application: household appliances, automotive, e-mobility and mechanical engineering

For an optimized process control ELASTOSIL® RT 708 is equipped with an UV-active fluorescent tracer, which allows optical detection of the silicone under black light. Best results are optained for black light sources having an emission maximum of 325 nm to 400 nm, while the fluorescence maximum of the tracer is between 400 nm and 475 nm.

 

Preparation:

All surfaces must be clean and free of contaminants that will inhibit the cure of ELASTOSIL® RT 708. 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.

 

To eliminate any air introduced during dispensing or trapped under components or devices a vacuum encapsulation is recommended. Alternatively, ELASTOSIL® RT 708 can be de-aerated prior to use; applying a vacuum of 25-50 mbar for 10-15 min is recommended.

 

Curing:

ELASTOSIL® RT 708 is a one-part heat-curing silicone, the curing time of which is highly dependent on temperature and on both the size and the heat sink properties of the components being potted. ELASTOSIL® RT 708 is usually cured between 140 °C and 200 °C in order to secure a quick build-up of adhesion to the respective substrate. Recommended curing temperatures and resulting curing times are given in adjacent table.

 

Detailed information about processing one-part heat-curing silicones is given in our brochure “ROOM TEMPERATURE VULCANIZING (RTV) SILICONES - MATERIAL AND PROCESSING GUIDELINES”. We recommend running preliminary tests to optimize conditions for the particular application.

 

Removal:

If removal of the silicone from machines or dispensing equipment is necessary, white spirit or similar nonpolar solvents are recommended. However, cleaning ideally should take place before the silicone is fully vulcanized. Cured silicone rubber needs to be rubbed off or removed mechanically, if necessary in combination with a swelling agent (solvent) or a chemical silicone remover.
 

Storage

Store in a dry and cool place.

 

The 'Best use before end' date of each batch is shown on the product label.

 

Storage beyond the date specified on the label does not necessarily mean that the product is no longer usable. In this case however, the properties required for the intended use must be checked for quality assurance reasons.

Sales and support

Wacker Chemical Corporation
S State Road 4950
Ann Arbor, MI 48108
United States
+1  888  922-5374 (Phone)
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Products Technical data
Hardness Shore A Tensile strength Elongation at break Tear strength
ELASTOSIL® RT 705 42[1] 42[1] 3.0 N/mm²[2] 3.0 N/mm²[2] 180 %[3] 180 %[3] 4.6 N/mm[4] 4.6 N/mm[4]
ELASTOSIL® RT 706 32[1] 32[1] 1.9 N/mm²[2] 1.9 N/mm²[2] 180 %[3] 180 %[3] 3.2 N/mm[4] 3.2 N/mm[4]
ELASTOSIL® RT 707 W 45[1] 45[1] 3.5 N/mm²[2] 3.5 N/mm²[2] 200 %[3] 200 %[3] - -
ELASTOSIL® RT 708 42[1] 42[1] 4.0 N/mm²[2] 4.0 N/mm²[2] 250 %[3] 250 %[3] 6.3 N/mm[4] 6.3 N/mm[4]
Legend
[1] Hardness Shore A | DIN ISO 48-4,  [2] Tensile strength | ISO 37 type 1,  [3] Elongation at break | ISO 37 type 1,  [4] Tear strength | ASTM D 624 B 

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Wacker Chemical Corporation
S State Road 4950
Ann Arbor, MI 48108
+1  888  922-5374 (Phone)

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