| 摘要 |
1. An alkaline, pulverised active substance for the deacidification of printed matter, in particular bound books, wherein the active substance is distributed over the printed matter by means of air, characterised in that the active substance comprises a mixture of at least two dried inorganic salts, the anionic parts of the salts having a relatively low acidity constant, wherein the main constituent of the active substance is potassium hydrogen carbonate having low water affinity and the second constituent of the active substance is potassium carbonate having high water affinity. 2. An alkaline active substance according to claim 1, characterised in that potassium carbonate is present in the active substance in an amount of 7% to 15% by weight and in that the active substance has an average particle size of 20 mum to 30 mum and a residual moisture content of less than 20% by weight. 3. An alkaline active substance according to claim 1, characterised in that potassium carbonate is present in the active substance in an amount of 0.1 % to 5% by weight and in that the active substance has an average particle size of 28 mum to 35 mum and a residual moisture content of less than 15% by weight. 4. An alkaline active substance according to either one of claims 2 and 3, characterised in that an addition of potassium hydrogen phosphate or ammonium thiocyanate is present in the active substance in an amount of 1% to 5% by weight. 5. An alkaline active substance according to any one of claims 2 to 4, characterised in that 0.5% to 2% by weight of polystyrene balls with a diameter of 0.2 mm to 2 mm is added to the active substance.
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