×

Granular fertilizer with a multilayer coating

  • US 5,645,624 A
  • Filed: 11/29/1994
  • Issued: 07/08/1997
  • Est. Priority Date: 07/21/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A granular fertilizer with a multilayer coating comprising a first layer as an inner layer containing at least one rapidly biodegradable polymer selected from the group consisting of poly-L-lactic acid having a weight-average molecular weight of 70,000 to 500,000, polycaprolactone having a weight-average molecular weight of 10,000 to 70,000, aliphatic polyester having a weight-average molecular weight of 10,000 to 50,000 represented by the following formula (1):

  • ##STR3## wherein m is 2 or 4, and x is 50 to 500; and

    polyurethane having a weight-average molecular weight of 25,000 to 500,000 represented by the following formula (2);

    ##STR4## wherein n is 5 or 6 and Y is 70 to 1500; and

    a water-insoluble second layer as an outer layer containing at least one slowly biodegradable polymer selected from the group consisting of at least one cellulose derivative having a weight-average molecular weight of 10,000 to 300,000 selected from the group consisting of of nitrocellulose, ethyl cellulose and triacetyl cellulose, low molecular weight polyethylene having a weight-average molecular weight of 500 to 10,000, low molecular weight wax having a weight-average molecular weight of 300 to 800, and a low molecular weight paraffin having a weight-average molecular weight of 300 to 800 or light degradable resin;

    wherein the first layer is in an amount sufficient to control the dissolving-out rate of the fertilizer nutrients, and the second layer is in an amount sufficient to control the biodegradability of the first layer.

View all claims
  • 3 Assignments
Timeline View
Assignment View
    ×
    ×