NO122899B

• Main Authors: HERRMANN H, MEHLO W
• Format: Patent
• Language: English
• Published: 30.08.1971
• Subjects: CINEMATOGRAPHY; ELECTROGRAPHY; ELECTROPHOTOGRAPHY; HOLOGRAPHY; MAGNETOGRAPHY; PHOTOGRAPHY; PHYSICS

1,061,288. Developing electrostatic latent images. KALLE A. G. Nov. 18, 1963 [Nov. 24, 1962], No.45453/63. Heading G2H. A toner powder consisting of rounded particles is produced by spray drying a solution of a natural or synthetic resin. Natural resins such as colophony, shellac or chlorinated rubber may be used. Extensive lists of synthetic resins, solvents therefor and black dyes which may either be dissolved or dispersed in the solution are given. Other materials such as pulverized iron, magnetite or glass dust may also be dispersed in the solution. The adhesion and melting point of the toner may be varied by adding 1-5% by weight of wax or low-melting point organic compound. The spray is subjected to the heat of infrared lamps and the solvent is removed in a current of air. In the examples mixed synthetic resins are used. Polystyrene can be mixed with a maleinate or chlorodiphenyl resin in trichloroethylene or a mixture of both and an oil-free alkyd resin having an acid number 80-90 and a melting range 63-80‹C., in a mixture of trichloroethylene and methylene chloride can be used. A black dye may be dissolved in the solution and/or a black pigment dispersed in it. In a further example, the alkyd and maleinate resins are dissolved in a mixture of trichloroethylene and methylene chloride together with a black dye. The product toner is used mixed with kieselguhr or iron powder.