Patent ID: 7902117

Claim:
Thermal paper composite comprising: (1) an active layer containing image forming components; and (2) a thermal paper composite precursor comprising a) a substrate layer; and (b) a base layer positioned on the substrate layer, the base layer comprising a binder, calcined kaolin, and at least one porosity improver, wherein said thermal paper composite precursor has a thermal effusivity that is at least about 2% less than the thermal effusivity of porosity improver-less thermal paper composite precursor, wherein said calcined kaolin in said base layer has at least one of: at least about 70% by weight of the particles having a size of 2 microns or less, at least about 50% by weight of the particles have a size of 1 micron or less, a surface area of at least about 5 m 2 /g, and a pore volume of at least about 0.1 cc/g, wherein if said at least one porosity improver is not a calcined clay then said at least one porosity improver has at least one of: at least about 70% by weight of the particles have a size of 2 microns or less, at least about 50% by weight of the particles have a size of 1 micron or less, a surface area of at least about 10 m 2 /g, and a pore volume of at least about 0.1 cc/g; and if said at least one porosity improver is a calcined clay then said at least one porosity improver has at least one of: at least about 70% by weight of the particles having a size of 2 microns or less, at least about 50% by weight of the particles have a size of 1 micron or less, a surface area of at least about 5 m 2 /g, and a pore volume of at least about 0.1 cc/g.