| 摘要 |
<p>1,192,621. Etching. FARBWERKE HOECHST A.G. 5 May, 1967 [5 May, 1966], No. 21017/67. Heading B6J. [Also in Divisions B1, C7 and H1] Fluorine-free, chlorine-free, bromine-free plastics are etched with an aqueous chlorine or bromine solution, with a liquid chlorohydrocarbon such as chlorobenzene, carbon tetrachloride, chloroform or tetrachloroethylene, or with a current of chlorine or bromine containing water vapour. Plastics containing fluorine are first treated with an alkali metal solution of, for example, sodium or potassium in liquid ammonia or phosphoric acid tridimethylamide, then are etched with an aqueous chlorine or bromine solution or wtih a current of bromine or chlorine and water vapour. The materials etched may be in the form of powders, granules or sheets and may include polyethylene, polypropylene, polyvinyl chloride, polytetrafluor. ethylene, polytrioxan, polyethylene terephthalate and phenol-formaldehyde resins.</p> |
