RTV31, RTV60 and RTV88 silicone rubber compounds are high temperature two-part silicone elastomers. They are supplied ready-to-use with a base compound and DBT (dibutyl tin dilaurate) as the standard curing agent. DBT is suitable for most applications, however other catalysts are available to facilitate deep section cure, faster cure and automated mixing.
RTV31, RTV60 and RTV88 silicone rubber compounds differ primarily in viscosity in the uncured state.
Key Features and Benefits
- Variable work times and cure rates by adjusting the amount and type of curing agent
- Room temperature cure
- Composition free of solvents and solvent odor
- Excellent adhesion capabilities with primer
- Excellent release properties
- Retention of elastomeric properties at temperatures from -54°C (-65°F) up to 260°C (500°F) continuously, and up to 316°C (600°F) for short periods of time
Typical Physical Properties
|UNCURED PROPERTIES OF RTV BASE |
|Color ||Red ||Red ||Red |
|Consistency ||Pourable ||Pourable ||Spreadable Paste |
|Viscosity, cps ||25,000 ||47,000 ||880,000 |
|Specific Gravity ||1.42 ||1.48 ||1.47 |
|UNCURED PROPERTIES OF RTV BASE WITH |
0.5% DBT CURING AGENT ADDED
|Work Time @ 25°C (77°F), hrs ||2 ||2 ||0.75 |
|Cure Time @ 25°C (77°F), hrs ||24 ||24 ||24 |
|CURED PROPERTIES (0.5 wt. % DBT Curing|
Agent added, cured 7 days at 25°C (77F) and 50%
|RTV31 ||RTV60 ||RTV88 |
|Mechanical|| || || |
|Hardness, Shore A Durometer ||54 ||57 ||58 |
|Tensile Strength, kg/cm2 (psi) ||61 (870) ||70 (990) ||59 (830) |
|Elongation, % ||170 ||120 ||120 |
|Tear Strength, kg/cm (lb/in) ||5 (29) ||7 (40) ||8 (42) |
|Shrinkage, % ||0.6 ||0.6 ||0.6 |
|Electrical|| || || |
|Dielectric Strength, kv/mm (v/mil) (1.9 mm thick) ||17 (430) ||17.7 |
|17.4 (440) |
|Dielectric Constant @ 1000 Hz ||4.4 ||4 ||4.3 |
|Dissipation Factor @ 1000 Hz ||0.03 ||0.02 ||0.03 |
|Volume Resistivity, ohm-cm ||1.6 x 1014||4.4 x 1014||2.8 x 1014|
|Thermal|| || || |
|Useful Temperature Range,°C (°F) ||-54 to 260 ||-54 to 260 ||-54 to 260 |
| ||(-65 to 500) ||(-65 to 500) ||(-65 to 500) |
|Thermal Conductivity (W/m·k)||0.31||0.31||0.31|
|Coefficient of Expansion, cm/cm°C|
|20 x 10-5|
(11 x 10-5)
|20 x 10-5|
(11 x 10-5)
|20 x 10-5|
(11 x 10-5)
|Specific Heat, cal/gm° C / |
Typical high temperature applications for these products include, but are not limited to:
- Potting and encapsulating electric motors and transformers
- Fabrication of rubber parts
- Casting molds for low-melting point metals
- Release applications such as rubber rollers
- Thermal insulation
Nothing contained herein shall be construed to imply the nonexistence of any relevant patents or to constitute a permission, inducement or recommendation to practice any invention covered by any patent, without authority from the owner of the patent.
Product Safety, Handling and Storage
Customers should review the latest Material Safety Data Sheet (MSDS) and label for product safety information, safe handling instructions, personal protective equipment if necessary, and any special storage conditions required for safety. MSDS are available at www.momentive.com or, upon request, from any Momentive Performance Materials (MPM) representative. For product storage and handling procedures to maintain the product quality within our stated specifications, please review Certificates of Analysis, which are available in the Order Center. Use of other materials in conjunction with MPM products (for example, primers) may require additional precautions. Please review and follow the safety information provided by the manufacturer of such other materials.
Select a mixing container 4 to 5 times larger than the volume of RTV silicone rubber compound to be used. Weigh out the RTV silicone rubber base compound and add the appropriate amount of curing agent. 0.5% DBT by weight will provide a work time or pot life of about one hour and a cure time of 24 hours. 0.5% DBT is the most commonly used concentration of curing agent for RTV31, RTV60 and RTV88 silicone rubber compounds. The pot life may be lengthened by using less DBT (as little as 0.1% DBT).
MEASURING GUIDE FOR CURING AGENT ADDITION
|RTV Weight||Dibutyl Tin Dilaurate Concentration|
|100 grams ||5 drops ||25 drops |
|454 grams (1 lb.) ||23 drops ||115 drops (2.27 |
With clean tools, thoroughly mix the RTV base compound and the curing agent, scraping the sides and bottom of the container carefully to produce a homogeneous mixture. When using power mixers, avoid excessive speeds which could entrap large amounts of air or cause overheating of the mixture, resulting in shorter pot life.
Air entrapped during mixing should be removed to eliminate voids in the cured product. Expose the mixed material to a vacuum of 25mm (29 in.) of mercury. The material will expand, crest, and recede to about the original level as the bubbles break. Degassing is usually complete about two minutes after frothing ceases. When using the RTV silicone rubber compound for potting, a deaeration step may be necessary after pouring to avoid capturing air in complex assemblies.
Using DBT curing agent at a level of 0.5%, these RTV silicone rubber compounds will cure in 24 hours at 25°C (77°F) and 50% relative humidity to form durable, resilient rubbers. Under these conditions a pot life of about one hour will typically be available for pouring and working with the catalyzed material. Pot life may be increased by refrigerating the mixed material at 0°C (32°F) after catalyzing.
A choice of curing agents is available for use with RTV31, RTV60 and RTV88 silicone rubber compounds.
|CuringAgent||Cure Speed||Curing Agent Concentration||Features|
|STO||fast||0.1-0.5%||small volume applications|
|RTV9811||moderate||5-10%||good deep section cure suitable for automatic mixing|
|RTV9950||moderate||5-10%||suitable for automatic mixing |
|RTV9910||slow||10%||suitable for automatic mixing|
Deep Section Cure
If these RTV silicone rubber compounds are to be used in deep sections at temperatures over 150°C (302°F), the cured product should be properly conditioned prior to service. Following room temperature cure of 1-3 days, a typical program would be eight hours at 50°C intervals from 100°C (212°F) to the service temperature. Longer times at each temperature will be required for larger parts or very deep sections.
If adhesion is an important application requirement, RTV31, RTV60 and RTV88 silicone rubber compounds require a primer to bond to non-silicone surfaces. Thoroughly clean the substrate with a non-oily solvent such as naphtha or methyl ethyl ketone (MEK) and let dry. Then apply a uniform thin film of a suitable silicone primer such as SS4004 silicone primer and allow the primer to air dry for one hour or more. Finally, apply freshly catalyzed RTV silicone rubber compound to the primed surface and cure as recommended.
Customers must evaluate Momentive Performance Materials products and make their own determination as to fitness of use in their particular applications.
From automotive to healthcare, from electronics to construction, products from Momentive Performance Materials Inc. are practically everywhere you look. We are a global leader in silicones and advanced materials with a 70+ year heritage of innovation and being first to market – with performance applications that improve everyday life. By knowing our customers’ needs and creating custom technology platforms for them, we provide science based solutions to help customers increase performance, solve product development issues and engineer better manufacturing processes.
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