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Slow release nitrogen fertilizer

  • US 6,936,681 B1
  • Filed: 03/26/2003
  • Issued: 08/30/2005
  • Est. Priority Date: 03/26/2002
  • Status: Expired due to Term
First Claim
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1. A particulate urea-formaldehyde polymer made by acidifying a aqueous methylol urea solution, wherein the aqueous methylol urea solution is made by reacting urea and formaldehyde at a urea:

  • formaldehyde mole ratio of from 0.7;

    1 to 1.25;

    1 and wherein the aqueous methylol urea solution either contains a dispersing agent or is subjected to a high shear condition during the acidifying, to form an aqueous dispersion of insoluble urea-formaldehyde polymer particles and drying the dispersion to recover the urea-formaldehyde polymer particles.

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