Abstract: In this paper, CM01 resin for hot melt prepreg was prepared by using bisphenol M cyanate ester resin as raw material, and employing the method of cyanate ester monomer pre-polymerization which is then catalysted by copper acetylacetonate and nonylphenol. The processability of the resin and the dielectric, hygroscopic, thermomechanical and mechanical properties of the cured resin were investigated. The properties of CM01 resin were compared with the ones of CA01 resin which was prepared by bisphenol A cyanate under the same conditions. The results show that CM01 resin has good processing fluidity, which is suitable for hot melt prepreg preparation. Prepregs prepared by CM01 resin have a wide window for high temperature pressing, thus suitable for composite molding. The cured CM01 resin has excellent dielectric and hygroscopic properties. The dielectric constant and dielectric dissipation factor of cured CM01 resin are 2.78~2.80 and 0.004 53~0.005 11 respectively in the frequency range of 7~15 GHz, while those of cured CA01 resin are 2.99~3.01 and 0.010 8~0.012 3 respectively. The saturated water absorption of cured CM01 resin is 0.85%, which is 60% lower than that of cured CA01 resin. The cured CM01 resin has good heat resistance and mechanical properties, the glass transition temperature T_g is 198.1 ℃, the tensile strength and tensile modulus are 66.51 MPa and 3.06 GPa respectively, the elongation at break is 2.39%, the flexural strength and flexural modulus are 134.45 MPa and 3.09 GPa respectively.

Key words: bisphenol M cyanate ester, bisphenol A cyanate ester, hot melt prepreg, dielectric properties, water absorption, composites