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Fibrous sheet materials

  • US 4,248,664 A
  • Filed: 06/13/1979
  • Issued: 02/03/1981
  • Est. Priority Date: 06/20/1978
  • Status: Expired due to Term
First Claim
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1. In a process for the production of a non-combustible asbestos-free board product comprising a matrix of ball clay reinforced with glassy inorganic fiber, including the steps of:

  • (i) dewatering on a sieve or other filter medium an aqueous suspension containing glassy inorganic fiber and ball clay as the major ingredients, with a small proportion of starch as binder, and(ii) subsequently setting the dewatered suspension at elevated temperature, the improvement which consists in;

    (a) employing as the aqueous suspension one which has a higher content of ball clay than of glassy inorganic fiber and which also contains organic web-forming fibers, the proportions of the various ingredients by weight of total solids in the suspension being;

    
    
    space="preserve" listing-type="tabular">______________________________________ unfired ball clay 42-67% glassy inorganic fiber 18-42% starch 1.5-5% organic web-forming fiber up to 7% ______________________________________ in combination with(b) limiting the setting at elevated temperature to a drying procedure which is carried out(b1) until the board product has a tensile strength greater than 2 MPa and a density at least 500 kg/m3 but less than 1200 kg/m3, and(b2) so as to leave the ball clay in the unfired state and the starch content in the range 1.5-5% by weight, to obtain a board product which is remoldable when rewetted with water.

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