  Two-dimensional materials are characterised by a number of unique physical
properties which can potentially make them useful to a wide diversity of
applications. In particular, the large thermal conductivity of graphene and
hexagonal boron nitride has already been acknowledged and these materials have
been suggested as novel core materials for thermal management in electronics.
However, it was not clear if mass produced flakes of hexagonal boron nitride
would allow one to achieve an industrially-relevant value of thermal
conductivity. Here we demonstrate that laminates of hexagonal boron nitride
exhibit thermal conductivity of up to 20 W/mK, which is significantly larger
than that currently used in thermal management. We also show that the thermal
conductivity of laminates increases with the increasing volumetric mass
density, which creates a way of fine-tuning its thermal properties.
