Patent GB-1073943-A (GB)
Title: Paper coating and resulting product
IPC: D21H19/70
Filed: 1964-08-04
Abstract: A coating composition suitable for high-speed application to a substrate to form on said substrate a bright opaque film exhibiting good printing characteristics and controlled ink holdout comprises (1) an aqueous dispersion of a film-forming binder-matrix material comprising casein and/or alpha protein or a mixture of casein and/or alpha protein with a water-dispersible elastomer, (2) starch, and (3) a partculate additive, and (b) a discontinuous phase comprising globules of a water-immiscible organic liquid having a boiling-point above that of water and present in a globule size range between about 0.5 and about 1.5 microns with no appreciable number exceeding 5 microns. The casein may be solubilized with ammonium hydroxide, sodium hydroxide, sodium tetraborate, sodium carbonate or trisodium phosphate and the composition may also contain zinc sulphate or a salt of copper, aluminium or chromium to form an insoluble caseinate in the final coating.  The organic liquid may be xylene, kerosene, mineral spirits, high flash naphtha, butyl methyl ketone, amyl ethyl ketone, octane, butyl acetate or amyl acetate. The particulate additive may be chalk, clay, titania, hydrated calcium silicate, aluminium or bronze powder, carbon black or ultramarine. The composition may be applied to paper, e.g. publication paper by a trailing blade coater and may be applied on the machine before the paper has completely dried; it may be applied at a temperature of 75 DEG  to 150 DEG  F.  The coated paper is then heated in two stages firstly to gel the continuous phase and secondly to dry the continuous phase completely and evaporate the discontinuous phase to give a cellular coating.  The coated paper may finally be calendered.ALSO:A coating composition suitable for high-speed application to a substrate to form on said substrate a bright opaque cellular film exhibiting good printing characteristics and controlled ink hold out comprises (1) an aqueous dispersion of a film-forming binder-matrix material comprising casein and/or alpha protein or a mixture of casein and/or alpha protein with a water-dispersible elastomer, (2) starch and (3) a particulate additive, and (b) a discontinuous phase comprising globules of a water-immiscible organic liquid having a boiling-point above that of water and present in a globule size range between about 0.5 and about 1.5 microns with no appreciable number exceeding 5 microns. The casein may be solubilized with ammonium hydroxide, sodium hydroxide, sodium tetraborate, sodium carbonate or trisodium phosphate and the composition may also contain zinc sulphate or a salt of copper, aluminium or chromium to form an insoluble caseinate in the final coating.  The organic liquid may be xylene, kerosene, mineral spirits, high flash naphtha, butyl methyl ketone, amyl ethyl ketone, octane, butyl acetate or amyl acetate. The particulate additive may be chalk, clay, titania, hydrated calcium silicate, aluminium or bronze powder, carbon black or ultramarine. The composition may be applied to paper, e.g. publication paper by a trailing blade coater and may be applied on the machine before the paper has completely dried; it may be applied at a temperature of 75 DEG  to 150 DEG  F.  The coated paper is then heated in two stages firstly to gel the continuous phase and secondly to dry the continuous phase completely and evaporate the discontinuous phase to give a cellular coating. The coated paper may finally be calendered.ALSO:A coating composition suitable for high-speed application to a substrate to form on said substrate a bright opaque film exhibiting good printing characteristics and controlled ink holdout comprises (1) an aqueous dispersion of a film-forming binder-matrix material comprising casein and/or alpha protein or a mixture of casein and/or alpha protein with a water-dispersible elastomer, (2) starch and (3) a particulate additive, and (b) a discontinuous phase comprising globules of a water-immiscible organic liquid having a boiling-point above that of water and present in a globule size range between about 0.5 and about 1.5 microns with no appreciable number exceeding 5 microns.  The casein may be solubilised with ammonium hydroxide, sodium hydroxide, sodium tetraborate, sodium carbonate or trisodium phosphate and the composition may also contain zinc sulphate or a salt of copper, aluminium or chromium to form an insoluble caseinate in the final coating.  The organic liquid may be xylene, kerosene, mineral spirits, high flash naphtha, butyl methyl ketone, amyl ethyl ketone, octane, butyl acetate or amyl acetate.  The particulate additive may be chalk, clay, titania, hydrated calcium silicate, aluminium or bronze powder, carbon black or ultramainre.  The composition may be applied to paper, e.g. publication paper by a trailing blade coater and may be applied on the machine before the paper has completely dried; it may be applied at a temperature of 75 DEG  to 150 DEG F. The coated paper is then heated in two stages firstly to gel the continuous phase and secondly to dry the continuous phase completely and evaporate the discontinuous phase to give a cellular coating. The coated paper may finally be calendered.ALSO:A coating composition suitable for high-speed application to a substrate to form on said substrate a bright opaque film exhibiting good printing characteristics and controlled ink holdout comprises (1) an aqueous dispersion of a film-forming binder-matrix material comprising casein and/or alpha protein or a mixture of casein and/or alpha protein with a water-dispersible elastomer, (2) starch and (3) a particulate additive, and (b) a discontinuous phase comprising globules of a water-immiscible organic liquid having a boiling-point above that of water and present in a globule size range between about 0.5 and about 1.5 microns with no appreciable number exceeding 5 microns.  The casein may be solubilised with ammonium hydroxide, sodium hydroxide, sodium tetraborate, sodium carbonate or trisodium phosphate and the composition may also contain zinc sulphate or a salt of copper, aluminium or chromium to form an insoluble caseinate in the final coating.  The organic liquid may be xylene, kerosene, mineral spirits, high flash naphtha, butyl methyl ketone, amyl ethyl ketone, octane, butyl acetate or amyl acetate.  The particulate additive may be chalk, clay, titania, hydrated calcium silicate, aluminium or bronze powder, carbon black or ultramarine.  The composition may be applied to paper, e.g. publication paper by a trailing blade coater and may be applied on the machine before the paper has completely dried; it may be applied at a temperature of 75 DEG  to 150 DEG F. The coated paper is then heated in two stages firstly to gel the continuous phase and secondly to dry the continuous phase completely and evaporate the discontinuous phase to give a cellular coating. The coated paper may finally be calendered.