Sealants are typically lower strength, yet flexible, bonding agents used between substrates of differing physical properties to form a seal between the materials. Sealants, despite not having great strength, convey a number of properties. They seal top structures to the substrate, and are particularly effective in waterproofing processes by keeping moisture out (or in) the components in which they are used. They can provide thermal and acoustical insulation, and may serve as fire barriers. They may have electrical properties, as well.
The main difference between adhesives and sealants is that sealants typically have lower strength and higher elongation than adhesives do. When sealants are used between substrates having different thermal coefficients of expansion or differing elongation under stress, they need to have adequate flexibility and elongation. Sealants generally contain inert filler material and are usually formulated with an elastomer to give the required flexibility and elongation. They usually have a paste consistency to allow filling of gaps between substrates. Low shrinkage after application is often required. Many adhesive technologies can be formulated into sealants.
Butyl owns the properties of tack, aging resistance and low permeability that makes it the ideal polymer for a variety of adhesive and sealing applications. It prevents the penetration of air, gas, noise, dust, fire, smoke, or liquid from one location through a barrier into another. Butyl products are used in adhesive formulations for transparent tapes, hot melt pressure sensitive adhesives, mastic for pipe wrap tapes, vinyl floor tile adhesives and roofing adhesives; self-fusing, semi-conducting electrical splicing tapes, eliminating the need for separate adesive coats; especially small openings that are difficult to shut with other materials, such as roof, gasket, sticky tape etc in construction, automotive and etc industries.
That shall be emphasised is the application of butyl for rubber closures of electrical condensers in electrical appliances. The assembly of an electrical condenser (or capacitor) is sealed by a rubber closure to prevent leakage of the content. Regular butyl rubbers are the choice for this application primarily because of the excellent impermeability to the electrolyte, which provides good seal ability.
|Application||Grade||Mooney ML(1+8) 125℃||Volatiles wt%|
|Sealant & Adhesive||IIR-532||51±5||≤0.3|