Silane surface-modified pyrogenic alumina, for use in toner - to increase charge stability, produced by spraying with silane mixt. free from solvent

摘要

Pyrogenic Al2O3 (I) is modified by spraying Al2O3 with 0.5-40 (wt.)% silane mixt. contg. 1-99 pts. trimethoxy-n-octylsilane (MeO)3-Si-(CH2)7-CH3 (II) and 99-1 pts. triethoxy-3-diaminopropylsilane (EtO)3-Si-(CH2)2-CH(NH2)2 (III). The surface-modified Al2O3 (I) has a surface area of 50-150 m2/g, tamped density of 50-90 g/l, drying loss less than 5%, calcination loss of 0.5-15%, C content of 0.5-12% and pH of 4-8. (I) is produced by placing Al2O3 in a mixer and spraying with a mixt. of (II) and (III), then mixing and tempering the mixt. at 100-150 deg.C. USE/ADVANTAGE - (I) is used as additive to toners (claimed) used in copiers and is free from solvent.