| 摘要 |
Cellulose fabrics are desized by oxidising the size with an alkali-metal bromite and/or an alkali-metal hypobromite at a pH greater than 9. Sodium bromite and/or hypobromite are preferably used, the pH value of the solution being adjusted by the addition of caustic soda. Alkali-metal bromides and bromates may also be present in the solution. The treatment may be carried out in a jigger-type apparatus for less than one hour with a solution containing no more than 5 grams of active bromine per litre of hypobromite or 2 grams of active bromine per litre of bromite. Alternatively the pressing or fulling process may be used in which the fabric is passed at a very high rate, e.g. 30 to 40 metres per minute, through a bath of the solution and pressed at the outlet of the bath between two presser rollers, the solution containing 10 grams (or less) of active bromine per litre with the hypobromite solution and 5 grams (or less) of active bromine per litre with the bromite. The desizing may be effected at ordinary temperature as a separate step prior to scouring or it may be effected concurrently with scouring by adding alkali metal bromite to the scouring bath, usually comprising soda and sodium carbonate, so that the bath contains less than 1 gram of active bromine per litre. Examples describe the desizing of cotton fabrics, there being added to the desizing solutions wetting agents, such as aryl-alkyl sulphonamides and sodium butylricinoleic ester sulphonate. Specification 843,558 is referred to. |
