| 摘要 |
Aluminium oxide based white filler comprising "retour powder" formed in the calcinating oven of the Bayer-type alumina manufacturing process, being either surface-treated or separated from the particles having a grain size above 5 microns, optionally in admixture with known additives, particularly zinc oxide or sulphur and/or a plasticizer, ageing retarder and/or accelerator. According to the invention there is also provided a process for the preparation of aluminium oxide based white filler which comprises (a) subjecting "retour powder" formed in the calcinating oven of the Bayer-type alumina manufacturing process to surface treatment with a solid or liquid agent; or (b) separating the "retour powder" formed in the calcinating oven of the Bayer-type alumina manufacturing process from the particles having a grain size above 5 microns; and, if desired, admixing the product obtained according to process (a) or (b) with known additives, particularly with zinc oxide, sulphur, and ageing retarder and/or an accelerator, and/or plasticizer. The advantage of the present invention is that the fillers obtained are cheap and when incorporated into rubber or plastics mixtures a significant improvement of the properties (e.g., tensile strength, abrasion, specific electric resistance, etc.) takes place. |
