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Retention and drainage aid for alkaline fine papermaking process

  • US 5,126,014 A
  • Filed: 07/16/1991
  • Issued: 06/30/1992
  • Est. Priority Date: 07/16/1991
  • Status: Expired due to Fees
First Claim
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1. A process in which fine paper is made by forming an aqueous cellulosic suspension having a pH in the range between about 6.8 to about 9.0, said cellulosic suspension comprising fibers, a precipitated calcium carbonate filler and a cationic starch strengthening agent, passing the suspension through one or more shear stages, draining the suspension to form a sheet and drying the sheet, wherein a cationic coagulant having a molecular weight in the range between about 2,000 to about 500,000 is added to said suspension in an amount between about 0.001% to about 0.5%, based on the dry weight of said suspension, prior to any of said shear stages, an anionic flocculant having a molecular weight of at least 5000,000 is added to said suspension in an amount between about 0.001% to about 0.8%, based on the dry weight of said suspension, after said coagulant but before any of said shear stages, and an inorganic material selected from the group consisting of:

  • bentonite and colloidal silica, is added to said suspension after at least one of said shear stages.

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