| 摘要 |
1,003,632. Printing surfaces. OXFORD PAPER CO. March 6, 1964 [May 2, 1963], No. 9612/64. Addition to 879,628. Heading B6C. A planographic printing plate comprises a base and a planographic coating thereon, said coating comprising a pigment mixture containing colloidal silica having a particle size from 7-40 millimicrons, and a substantially completely hydrolysed polyvinyl alcohol constituent which has been insolubilized by the colloidal silica, said silica being the only insolubilizing agent present in the coating. The polyvinyl alcohol is preferably at least 98% hydrolysed and the colloidal silica comprises between about 10-50% of the pigment mixture which also advantageously contains clay. Other pigments such as calcium silicate, barium sulphate, and titanium dioxide may be used in place of or in addition to the clay. A salt such as zinc phenol sulphonate, zinc sulphamate, zinc silicofluoride, zinc chloride, zinc acetate, alum, ammonium chloride, ammonium sulphate, or ammonium phosphate, as well as salts of lead, calcium, manganese, cerium or lanthanum may be added to the coating composition. Acetic acid may be added as a thinner. |
