| 摘要 |
Polyethylene having an average molecular weight of at least 1,500, a crystallinity of at least 75% and a density of at least 0.93 has been found advantageous as a base material for making pressure-fixable toner powder for developing electrostatic images. The toner powder can be fixed satisfactorily to image substrates by the pressure of fixing rollers of conventional electrophotographic copying apparatus, yet it can be produced readily by grinding a suitable composition based on the polyethylene. The polyethylene preferably has an average weight of between 2,000 and 10,000, a crystallinity of at least 80% and a density of at least 0.94. Especially advantageous pressure-fixable, electrically conductive toner powders are obtained from pigmented masses of the polyethylene in which 3 to 20% of the weight consists of carbon black having a specific surface of at least 750 m2/g, preferably of about 1,000 m2/g, and an oil absorption of between 250 and 400 ml/g. |
