| 摘要 |
Articles are bleached by damping them in a bath containing hydrogen peroxide, preferably 4 to 8 per cent and at a temperature up to 50 DEG C., then treating them with steam in a separate chamber, whereby their temperature is raised to 90-95 DEG C. in about 1 minute, and finally adding an alkaline catalyst to effect decomposition of the hydrogen peroxide; the supply of steam is continued for about the 30 seconds needed to decompose the peroxide and for a further minute thereafter to complete the bleaching; the catalyst may be gaseous ammonia or a finely divided solid or liquid material, e.g. sodium carbonate. Articles so treated may be flax, hemp, jute, straw, grass, wool, cotton, feathers, sponges, hair, felt, silk, horse-hair or leather. The correct degree of bleaching may be obtained by using a measured quantity of hydrogen peroxide of known concentration, or by removing the excess before steaming, e.g. by centrifugal separation, pressing or dripping. The process may be continuous.ALSO:The Specification as open to inspection under Sect. 91 states that articles such as bones, horn and ivory may be bleached by a two-step process, the articles being first damped with hydrogen peroxide and then brought into contact with an alkaline catalyst for the decomposition of the peroxide. The bleaching bath may contain from 4 to 8 per cent of hydrogen peroxide, stabilised with phosphoric acid, and the articles are soaked for a very short time, e.g. 1 to 2 minutes, at a temperature up to 50 DEG C. The main bleaching process is then effected in a closable vessel, the temperature of the articles being raised to 90 - 95 DEG C. with steam. The alkaline catalyst is then introduced, which may be gaseous ammonia or a finely atomised liquid or solid compound, and bleaching is effected in a very short time. The process may be continuous. This subject-matter does not appear in the Specification as accepted. |
