| 摘要 |
An improved form of calcium carbonate which is acid-resistant to enable its use as a filler material in the making of neutral to weakly acidic paper, and a process for producing this acid-resistant calcium carbonate is provided. This acid-resistant calcium carbonate composition comprises calcium carbonate and at least about 0.1 % to about 25 % based on the dry weight of the calcium carbonate, of sodium silicate, together with at least 0.1 % to about 25 percent, based on the dry weight of the calcium carbonate, of a weak acid, such as phosphoric acid, formic acid, fluoroboric acid, polyacrylic acid, or alum, or a mixture of weak acids, such as phosphoric acid and polyacrylic acid.
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