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Aqueous dispersion of gypsum and its use as a filler and coating pigment in the production of paper and cardboard

  • US 4,927,463 A
  • Filed: 03/30/1989
  • Issued: 05/22/1990
  • Est. Priority Date: 04/08/1988
  • Status: Expired due to Fees
First Claim
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1. An aqueous dispersion comprising gypsum and a surface-active, anionic compound, wherein said surface-active compound is a phosphoric acid ester selected from the group consisting of (1) an acidic phosphoric acid ester of the formula:

  • ##STR3## wherein R1 and R2 are the same or different and are alkyl poly(oxyethylene), alkyl poly(oxypropylene), alkylphenoxyalkyl or alkylphenyl polyoxyalkyl radicals, (2) a monophosphoric acid ester of a monoor dihydroxyalkylurea or of an alkoxylated mono- or dihydroxyalkylurea, and (3) a phosphoric acid ester of a poly-alkoxylated amine, in which one or more hydroxyl groups are are be esterified with phosphoric acid.

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