Two component, highly flexibilized epoxy for bonding, sealing and coating

Key Features

  • High peel strength
  • Outstanding adhesion to rubbers
  • Excellent thermal cycling resistance
  • Withstands 1,000 hours 85°C/85% RH

Product Description

Master Bond EP21TDC-4 is a two component, very flexible epoxy for high performance bonding, sealing and coating. It has a non-critical one to four mix ratio by weight. This system has a relatively long open time of 90-120 minutes for a 100 gram mass. EP21TDC-4 has a room temperature cure that can be accelerated by adding heat. The optimum cure schedule is 12 hours at 75°F followed by 3-5 hours at 140-160°F. An unusual feature of this product is that straight heat curing results in a product that is slightly softer (50-60 Shore A), than the one with the optimum cure (75-85 Shore A). The cured system has a peel strength greater than 25-35 pli and an elongation of 100--150%. EP21TDC-4 bonds well to a wide variety of metals, plastics and especially rubbers. In fact, it usually adheres well to rubbers such as neoprene, nitrile, SBR and occasionally EPDM, although surface treatment of the rubbers (especially EPDM) will allow for better adhesion. EP21TDC-4 has excellent electrical insulation properties along with good chemical resistance to oils and water. The epoxy has superior resistance to rigorous thermal cycling along with an outstanding ability to resist mechanical shock and vibration. The color of Part A is clear and Part B is amber-brown. It has an operating temperature range of -100°F to +250°F. EP21TDC-4 can be used in aerospace, electrical, OEM, electronic as well as repair and maintenance applications, where the special properties described above are desirable.

Product Advantages

  • Non-critical, one to four mix ratio, by weight, available in pre-measured kits
  • High peel strength
  • Withstands rigorous thermal cycling and shock
  • Bonds especially well to rubber including neoprene, nitrile, SBR and occasionally EPDM
  • Very good electrical insulator

Industrial Certifications

1,000 Hours at 85°C/85% RH

Meets EU Directive 2015/863



Gun Applicator


EP21TDC-4 is available is various sizes and units to accommodate customer's needs.

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