Spherical hollow particles of calcium carbonate were successfully obtained by the interfacial reaction method at highyields. Primary particles of 50 nm in diameter in mixed crystal forms of calcite and vaterite were found to comprisethe spherical hollow particles as the secondary structure. As a filler for internal loading to paper, the spherical hollowparticles maintained the density of the loaded handsheets from a large reduction and increased specific lightscattering coefficient to a great degree probably because of the porous structure. This optical effect was higher thanconventional ground calcium carbonate, but lower than the commercial coagulated scalenohedral particles with alarge surface area. In the print quality evaluation of coated paper containing the spherical hollow particles, moreaddition of the particles provided higher ratios of wax ink transfer from ribbon to paper in thermal wax-transferprinting. The efficient thermal insulation due to the porous structure was expected to maintain the temperature of theheated head high as well as the effect of higher smoothness with more addition of the spherical hollow particles.
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