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Highly filled sheets and method of preparation thereof

  • US 4,225,383 A
  • Filed: 12/14/1978
  • Issued: 09/30/1980
  • Est. Priority Date: 02/02/1978
  • Status: Expired due to Term
First Claim
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1. A method for preparing a sheet comprising:

  • (I) providing an aqueous dispersion of from about 1 percent to about 30 percent of a water-dispersible fiber;

    (II) mixing therewith (A) from about 60 percent to about 95 percent of a finely-divided, substantially water-insoluble, non-fibrous, inorganic filler and (B) from about 2 percent to about 30 percent of a binder containing a film-forming, water-insoluble, organic polymer in the form of an ionically stabilized latex having not greater than 0.7 milliequivalent of bound charge per gram of polymer in the latex;

    (III) colloidally destabilizing the resulting mixture to form a fibrous agglomerate in aqueous suspension having the characteristics that at a concentration of 100 grams of solids in 13,500 milliliters, the suspension will drain in a time of from about 4 seconds to about 120 seconds in a 10-inch by 12-inch Williams Standard Sheet Mould having a 2-inch outlet and a 30-inch water leg and fitted with a 100-mesh, stainless steel screen having a wire diameter of 0.0045 inch to provide in one pass at least 85 percent retention of solids which contain at least 60 percent by weight of filler;

    (IV) distributing and draining the aqueous suspension on a porous support to form a wet web; and

    (V) drying the web;

    said ionically stabilized latex being devoid of sufficient non-ionic stabilization to interfere with formation of the fibrous agglomerate;

    said percentages being on a dry weight basis, calculated on the total dry weight.

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