| 摘要 |
Pigment-based agent (I) for increasing the printability of paper or cardboard is produced by: (a) making an aq. colloidal system (II) from pigment(s) (III) and water-soluble or swellable hydrogel(s) (IV) contg. anionic gps.; (b) coacervation of (II) with a quat. organic ammonium salt (V); and (c) concn. by sedimentation, centrifuging and/or press filtration. The claims also cover (I). Pref. (III) is kaolin. Pref. (IV) is produced from a hydrated cation-exchangeable smectic laminar silicate with an ion exchange capacity of 50-120 milliequiv./100 g, pref. Na bentonite; or a natural or synthetic organic polymer. (V) has 8-22 C alkyl gp(s). and pref. is stearyldimethylbenzylammonium chloride or distearyldimethylammonium chloride. (II) has a total solids content of 2-15, pref. 3-5 wt.%; and the (III):(IV) ratio is such that 5-40, pref. 10-20% of the (III) particles are coated by coacervation. Coacervation is carried out in the presence of a fat- or oil-soluble optical whitener. |
