BMI-689M Low Viscosity Liquid Bismaleimide

BMI-689M is a lower cost alternative to our standard BMI-689.  It is made with the same ingredients but with a streamlined (less expensive and more tuned to high volume capable) process. BMI-689M is darker in color and higher in viscosity but still much lower in viscosity when compare to the other liquid BMI resins.

 

Note: both the BMI-689 and BMI-689M use a partially hydrogenated backbone material (maybe >75% hydrogenated). It was made specifically this way vs. using fully hydrogenated raw materials to both avoid patent concerns while making it less expensive. There are no patent concerns presently with the BMI-689M formula.  Though one would imagine that it is desirable to use fully hydrogenated raw materials to avoid any reactions with the left over double bonds that are possible with the partially hydrogenated material, in the many years experience we have with both the BMI-689 and BMI-689M, this concern appears to be unwarranted.

 

BMI-689M is a unique low viscosity liquid bismaleimide based on a non-hydrogenated dimer diamine backbone. It can be homo-cured via UV or free radical initiators to form tough, hydrophobic, cross-linked polyimides. The material has excellent low pH hydrolytic resistance and thermal stability. The amorphous nature of this BMI allows it to be used in a variety of applications including mixed cure systems (e.g. epoxy and BMI), mixed BMI systems or where a low viscosity, free radical cured resin is required. It is soluble in most aromatic and aliphatic solvents such as toluene, xylene, NMP, etc.

 

BMI-689M is recommended for use as an additive or base resin in adhesives that are designed for high temperature resistance. It has excellent adhesion to a variety of substrates. When used as a base resin, it can produce films that are tough, flexible and demonstrate good peel strength. BMI-689M is darker in color compared to BMI689 and higher in viscosity but still much lower in viscosity when compare to the other liquid BMI resins.

 

BMI-689M cures free radically so it is subject to oxygen inhibition to some degree. Thermal curing with an abundance of catalyst will usually overcome the problem. Bmi resins do demonstrate self photoinitialization when exposed to UV but polymerization is more complete and requires much less energy when a UV photoinitiator is used in the formula. We would not suggest using UV without an initiator for our BMI resins. Our favorite initiator is Irgacure IR-819. It works well in broad band and i-line systems.