Oce-nederland B.v.

Gerardus C Vercoulen

Marcel L Pennings

Antoon L Hoep

Johannes F Van Gageldonk

Lambertus M Van Sas

Arnold B Van Der Meij

Robert P Faessen

Arnold B Van Der Mey

A method of forming visible images in which magnetically attractable toner powder comprising resin particles containing magnetically attractable material is introduced to an image forming zone between an image registration medium and a moving conveying medium which has, within said image forming zone, a magnetic induction of at least 0.2T at its surface, thus imparting a force of attraction on the toner powder in which image forming zone the toner powder is selectively deposited on the image registration medium by electrostatic attraction in accordance with an image pattern, the toner powder used containing no more than 3% by volume of the magnetically attractable material.

Method of forming visible images

A fluorine-doped tin oxide powder is prepared by combining a solution of a stannic salt with a solution of a fluoride, separating the tin hydroxide from the liquid and drying it at a temperature not exceeding about room temperature and heating the dried product to at least 500.degree. C., until the fluorine content is less than 10% and preferably is between 1 and 5% by weight. The fluorine-doped tin oxide powder of the invention can be used for the manufacture of electrically conductive toner powder.

Process for preparing a fluorine-doped tin oxide powder

A toner powder comprising toner particles which carry on their surface and/or in an edge zone close to the surface fine particles of electrically conductive material consisting of fluorine-doped tin oxide. The fluorine-doped tin oxide particles have a primary particle size of less than 0.2 micrometer and a specific electrical resistance of at most 50 ohms.meter. The fluorine content of the tin oxide is less than 10% by weight, and preferably is from 1 to 5% by weight.

Toner powder comprising particles having a coating of fluorine-doped tin

A colored magnetically attractable toner powder comprising magnetically attractable material finely distributed in, or enveloped by, a coloring substance of thermoplastic resin and yellow fluorescent dye. The combination of yellow fluorescent dye and thermoplastic resin is selected such that a standard mass which comprises titanium dioxide and said thermoplastic resin in a weight proportion of 1:4, and also comprises yellow fluorescent dye in such an amount that the maximum fluorescence is observed, has the following characteristics: light-reflection between 400 and 450 nm at most 15%, fluorescence peak between 500 and 580 nm, light-reflection at fluorescence peak at least 120.degree., lightness at least 90, chroma at least 90.

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Velden, Netherlands

Gerardus C Vercoulen