| 摘要 |
<p>410,742. De-inking printed paper. ALSTED, L. L., Appleton, Wisconsin, U.S.A. Oct. 21, 1932, No. 29490. Convention date, Oct. 24, 1931. [Class 96.] Paper containing ground wood and printed on with an ink capable of being bleached is made available for reprinting and use by subjecting the ink to the reducing action of a sulphite bleaching agent, followed if desired by treatment with a neutralizing agent, whereby the colour of the ink is destroyed while the paper is maintained white or at its original colour. The paper is shredded and treated when suspended in water with the bleaching agent which also bleaches the ground wood in the pulp. Sulphurous acid is employed as the bleaching agent and borax as the neutralizing agent. The ink is formed from materials of two groups of black or nearly black dyestuffs of coal tar dyes capable of being discharged by hydrosulphites, or of the group of vegetable dyestuffs such as tannin dyes and dye wood extracts. The dyestuff is converted into insoluble or nearly insoluble lakes by known methods, the coal tar dyes nearly all yielding insoluble lakes with barium chloride and the dye woods and tannins with iron and manganese salts. Reference has been directed by the Comptroller to Specifications 117,023 and 320,430, [both in Class 146 (iii)].</p> |
