Method of making paper

  • US 6,372,089 B1
  • Filed: 02/14/2000
  • Issued: 04/16/2002
  • Est. Priority Date: 03/06/1998
  • Status: Expired due to Term
First Claim
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1. A method for making a cellulosic sheet comprising:

  • a. forming a cellulosic furnish containing from 0.01 to 1.5 percent by weight cellulosic fiber;

    b. adding to said furnish;

    (i) from about 0.00005 to about 1.25 percent by weight, based on the dry weight of fiber in said furnish, of a stable colloidal silica;

    wherein said stable colloidal silica has an S-value of from 20-50 and has a percent by weight solids concentration between about 7 and about 20% by weight silica;

    wherein the silica particles in said stable colloidal silica have a surface area of from greater than about 700 m2/g to less than about 970 m2/g;

    wherein the silica particles in said colloidal silica have a surface area that remains above 700 m2/g as the colloidal silica is aged at room temperature for a period of at least 30 days;

    wherein the S-value of said stable colloidal silica remains in the range of from 20-50 as the colloidal silica is aged at room temperature for a period of at least 30 days;

    wherein said stable colloidal silica does not include any aluminum; and

    (ii) from about 0.001 to about 0.5 percent by weight, based on the dry weight of fiber in the furnish of a substantially water soluble polymeric flocculant having a molecular weight greater than 500,000 daltons; and

    c. dewatering said furnish to obtain a cellulosic sheet.

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