1,087,201. Printing processes. RANK XEROX. Ltd Feb. 5, 1965 [Feb. 28, 1964], No. 5082/65. Heading B6C. [Also in Division G2] A powder image 19 which has been developedon, or transferred to, the surface of a coating 14 of micro-capsules supported on a plastic or paper substrate 13 is fixed, by applying a uniform pressure to.rupture the capsules and release a fixing liquid. As shown, to obtain a pair of mutually reversed copies, instead of a single copy, a blank sheet 21 is placed with its face downwards over the powder image and pressure is applied to both sheets-by rollers 17 and 18. Examples are given of capsules containing a solvent for toner powders of gum copal sealing wax, coumarone indene, polystyrene, rosin modified phenol formaldehyde and copolymers of methacrylic esters and styrene. The solvent causes the major component of the powder to become tacky and adhere to the substrate. Alternatively, the capsules may contain an air hardenable liquid adhesive to secure insoluble toner particles of thermosetting resin or metal powders. As a further alternative, the capsules may contain thesolution of a leuco dye base in an oil such as olive oil, sperm oil, coconut oil or cottonseed oil. The dye is formed by reaction with acidified toner particles of silica gel, alumina, infusorial earth or acid clay. In a modification, the capsules contain a solution of an organometallic compound such as nickel acetylacetonate and the toner particles are of or include rubeanic acid. On rupturing the capsules, the rubeanic acid reacts to produce an intensely coloured nickel complex salt which is absorbed in the paper substrate allowing the remaining tonerparticles to be brushed off.
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