| 摘要 |
893,105. Printing processes. AUSTRALIA, COMMONWEALTH OF. Dec. 18, 1958 [Dec. 24, 1957], No. 40914/58. Drawings to Specification. Class 100(2) [Also in Group XX] A phtographic reproduction from a master is made by applying a uniform layer of photoconductive material thin enough to be translucent to a light-transmitting backing (e.g. glass with a transparent film of cadmium oxide), producing an electrostatic charge on the layer, exposing the layer to light in contact with the master to form an electrostatic image, developing the image with a liquid developer comprising a pigment in a carrier having a resistency not less than 10<SP>10</SP> ohmcentimetre and a dielectric constant less than 3, transferring the developed image while wet by contact to a receiving base, and fixing the image to the base. The light may be passed through the back of the charged layer to be reflected by the master. The photo-conductive material may be amorphous selenicum, zinc oxide or lead iodide dispersed in a resin insulation matrix, or linseed oil boiled with sulphur or phosphorus. Dyes may be added, e.g. rose benzoyl rosin, erychrosin, or white dyes. The layer is then polished. Selenium in the non-image areas may be removed with carbon disulphide. Surplus photo-conductive material after transfer is washed away with acetone. The thickness of the photo-conductive layer is 1À5-20 microns for selenium, or up to 100 microns for zing oxide. The receiving base may be paper treated with a weak solution of casein glue; gums such as arabic, mesquite, hrardye, locust bean, geioir, ammonium alginate and sodium alginate; proteins such as casein, soya bean, zein, animal glue, gelatin and albumen; synthetics such as carboxy methyl cellulose, sodium polyamylate, methyl cellulose, hydroxy ethyl cellulose, polyvinyl alcohol; synthetic resins such as modified alkyd resins, or Caladine resins; starch, dextrin, pectine and latex derivatives; cr pressure-sensitive tapes. Specification 879,464 is referred to. |
