Bomar Oligomer Product
UV/EB Oligomer


BR-641S: Difunctional Aliphatic Polybutadiene Urethane Acrylate

BR-641S is an IBOA-free polybutadiene (PBD) urethane acrylate oligomer designed to meet rigorous electronic applications. BR-641S has many desirable properties typical to PBD resins combined with UV-curability. In applications requiring thermal cycling resistance, BR-641S withstands the extremes of temperature typical of such tests without undue degradation of properties.

Neat Properties
Property Value
Viscosity cP (60ºC) 66,000
Pt-Co (APHA) Color 50
Refractive Index (25ºC) 1.480
Density, g/cm3 (25ºC) 0.93
Monomer Dilution Properties
Property I30 I50 TM50 TP50 H50 HE30
Tensile Strength (MPa [psi]) 9.7 [1400] 15.2 [2200] II II II II
Elongation (%) 300 250 II II II II
Elastic Modulus (MPa [ksi]) 1.4 [0.2] 3.4 [0.5] II II II II
Durometer Hardness 55A 80A II II II II
Water Absorption (%) 24hrs
MEK Double Rubs (#) 30 30 II II II II
Viscosity (cP) 35000 @ 25ºC 4000 @ 25ºC II @ 25ºC II @ 25ºC II @ 25ºC II @ 25ºC

** Tensile Properties per ASTM D882   - Not Tested   || Incompatible   X Unable to Measure


  • Hydrophobic Character
  • Acid/Base Resistance
  • Low Temperature Flexibility
  • Excellent Dielectric Properties
  • High Temperature Resistance


  • Adhesives
  • Electronics
  • Conformal Coatings
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