Bismaleimide Resin Solution (BMI/DDM in MEK, Prepreg Grade)

Bismaleimide Resin Solution is a pre-formulated blend of BMI monomer and DDM co-reactant dissolved in methyl ethyl ketone (MEK) or N-methylpyrrolidone (NMP) solvent at 40-60% solids content. This ready-to-use solution eliminates the need for customers to blend BMI and DDM at precise ratios and is optimized for direct prepreg impregnation by hot-melt or solvent-dip/drum winding processes.

The BMI/DDM ratio is precisely controlled at 100:30-35 (by weight) in the solution to provide the balance of toughness, Tg, and processability established in the classic BMI/DDM system. The solution remains stable for 3-6 months at -18°C cold storage, enabling pre-formulation inventory management. Viscosity at 25°C is 500-2,000 mPa·s in solvent — suitable for direct fiber impregnation via solution bath for woven fabrics and unidirectional tapes.

After solvent evaporation, the resulting B-staged BMI/DDM prepreg has tack and drape characteristics comparable to 177°C epoxy prepregs, enabling manual and automated lay-up of structural aerospace composite parts. The cure schedule follows the standard BMI/DDM protocol: 150°C gel + 177°C/2h + 230°C/4h post-cure. Applications include aerospace structural prepreg for engine nacelles, hot-zone composite control surfaces, military aircraft composite structures, and composite tooling prepregs for 230°C post-cure tooling applications.