  In low temperature experiments, resins have many applications as glues or
thermal and electrical insulators. Cyanate ester resins (CEs) are a
high-temperature compatible thermoset resin whose glass-transition temperature
$T_g$ is ~300 $^\circ$C. Recently, we found that CEs also withstand low
temperatures without microcracking by measuring $^4$He permeability. Here, we
measured specific heat C, thermal conductivity \kappa, and magnetic
susceptibility $\chi$ of different kinds of CEs in the wide temperature range
from room temperature to 0.5 K for C and 2 K for other two. The thermal
properties, C and \kappa, of different kinds of CEs are surprisingly coincident
with each other. We discuss chemical structures and crystallinity of CEs and
their blends based on the measured thermal properties. Compared to Stycast
1266, a commonly-used epoxy resin in low temperature experiments, C of CEs is
larger by a factor of 3 (<= 30 K), \kappa is lower by a factor of 4 (<= 10 K),
indicating the small thermal diffusivity. The \chi values are as small as
Stycast 1266, indicative of their high purity. Our results show that cyanate
esters are a new option for cryogenic resins with thermal insulative properties
in/for low temperature experiments.
