UL Certifications

Designed to mitigate the worst effects of fires, fire retardant materials play a particularly important role in aircraft construction. Used in aircraft, epoxies and silicones must maintain their primary role as adhesives or coatings while exhibiting resistance to heat and flame in accordance with government and industry specifications. Master Bond’s series of flame retardant epoxies and silicones comply with specifications for flame resistance and reduction of smoke density and toxic emissions.

Two part silicone potting/encapsulation compound. Superior thermal conductivity. High elongation. Long pot life. Cures in thicknesses beyond 1-2 inches. UL 94V-0 flame retardant system. Serviceable from -65°F to +221°F.

Featuring a non-halogen filler, Master Bond EP21FRNS-2 passes UL 94V-0 testing for flame retardancy in potting, encapsulation and casting applications. It produces very low smoke levels and is well suited for the computer, aerospace and related industries. EP21FRSN-2 is a room temperature curing two component epoxy system that resists high temperatures up to 90°C.

Master Bond EP21AC is a two part epoxy with a non-halogenated filler that is formulated for applications where arc resistance and flame retardancy are required. Electrical arcing is a challenge for numerous electronic or electrical devices; this occurs when electricity jumps from one connection to another, resulting in an electrical breakdown. The air surrounding the current becomes ionized and arcs, which may lead to combustion and fire. EP21AC is designed primarily with the aim to prevent arcing related issues. “EP21AC withstood over 150 arcs without igniting and therefore was assigned the highest PLC (Performance Level Category) of 0 under the UL746A High Amp Arc Ignition test,” says Rohit Ramnath, Senior Product Engineer. “The compound is also flame retardant, as per the UL94HB standard for flammability testing. This combination of unique performance properties makes EP21AC suitable for encapsulating, potting or coating in many demanding applications.” The system is toughened, with an elongation of 10 to 20%, and is capable of resisting thermo-mechanical stresses. It is an excellent electrical insulator with a volume resistivity greater than 1014 ohm-cm, and a dielectric constant of 4.7 at 75°F. Other noteworthy properties include a tensile strength of 5,000-6,000 psi, and a tensile modulus of 300,000-350,000 psi at 75°F. It is serviceable over the temperature range of -60°C to +90°C [-75°F to +194°F]. EP21AC has a convenient to use 1 to 1 mix ratio by weight and cures at room temperature, or more rapidly with heat. It has good flow properties with a mixed viscosity of 30,000-50,000 cps, and a relatively long working life of 75-120 minutes at room temperature. This compound bonds well to a variety of substrates including metals, ceramics, composites and many plastics and rubbers. It is available for use in ounce kits, ½ pint, pint, quart and gallon container kits. Specialty packaging is also available in premixed and frozen syringes.

Master Bond EP41S-6 is a new two component epoxy system that meets UL 1203, which is defined by Underwriters Laboratories as the “Standard for Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous (Classified) Locations”. To meet the UL 1203 requirements, samples of EP41S-6 were exposed to saturated vapors in air for the following chemicals: acetic acid (glacial), acetone, ammonium hydroxide (20% by weight), ASTM reference fuel C, diethyl ether, ethyl acetate, ethylene dichloride, furfural, n-hexane, methyl ethyl ketone, methanol, 2-nitropropane, and toluene. After 168 hours of exposure to these vapors, sample castings in groups of 6 were observed for discoloration, swelling, shrinking, crazing, cracking, leaching, and dissolving. The samples were also subjected to a crush test before and after exposure to these chemicals. The crushing force for EP41S-6 was not less than 85% of the original value. EP41S-6 has successfully met or exceeded the requirements of these tests. EP41S-6 can be used in potentially explosive environments, as defined in National Electrical Code, NFPA 70 (National Fire Protection Association). In fact, EP41S-6 is suitable for use not only in Class I, Division 1 Groups A, B, C and D but also in Class II, Division 1, Groups E, F and G. Class I, Division 1 Groups A, B, C and D include flammable or hazardous conditions that can exist under normal operation conditions for acetylene, hydrogen, ethylene and propane. Class II, Division 1 includes combustible dusts, with Groups E, F and G covering metal dusts, carbonaceous dusts and non-conductive dusts respectively. EP41S-6 is a thermally stable compound possessing a glass transition temperature of 145-150°C and serviceability from -80°F to +500°F [-62°C to +260°C]. It offers a high dielectric strength of 440 volts/mil at 75°F for a 0.125 inch thickness. The optimal cure schedule for EP41S-6 is overnight at room temperature, followed by 6-8 hours of heat curing at 150-250°F. With a mixed viscosity of 30,000-40,000 cps at 75°F, this compound features good flow properties making it ideal for sealing and potting applications for electrical feedthroughs across various industries.