PIGMENT MATERIALS AND THEIR PREPARATION AND USE

摘要

A new composite material which is useful as a pigment in paper making or paper coating is described. The new material is produced by precipitating a white insoluble pigment compound, e.g. calcium carbonate, in an aqueous suspension containing fine particulate material preferably at least part of which is fresh, i.e. previously unused, e.g. titanium dioxide particles, and fibres, e.g. cellulosic fires. These may be derived from separate stocks and added together to produce the composite pigment material. The new material comprises a bonded matrix of the fibres and the white pigment compound having particles of the fine particulate material, e.g. TiO2, dispersed and bonded within the matrix. The new material may itself exist as particles in dry or wet form which may be further treated in a known way prior to use in paper making or paper coating. Use of the new material allows expensive fine particulate material such as TiO2 particles to be better retained in a paper making composition whilst at the same time avoiding the problem of agglomeration or "crowding" of the fine particles which in the prior art is known to affect adversely the optical properties of the composition produced using the fine particles.