摘要 |
<p>Staple fibres may be in the form of a fibrous web which prior to deposition of the aromatic substances is treated by an alkaline solution such as sodium hydroxide, the amount of which in the solution comprises of from 20 to 40 g. per litre of water. Cellulose fibres are additionally impregnated with a metallic salt, the amount of which does not exceed 2% by wt. of the fibres. Metallic salts are used to neutralise the residual alkalis in the fibres. They are furthermore treated with an oxidising agent such as sodium nitrate or persulphate. Metallic salts are represented by magnesium sulphate, iron (III) chloride or nitrates or sulphates of cobalt, chromium, lithium, sodium, potassium, magnesium or manganese.</p> |