Patents Assigned to Donlar Corporation
  • Production of polyaspartic acid from maleic acid and ammonia
    Patent number: 5373088
    Abstract: Polyaspartic acid is produced by thermal condensation of ammonium maleate derived from maleic acid and ammonia. Solid ammonium maleate in particulate form is heated to a temperature of at least about 170.degree. C. to effect thermal condensation to a polysuccinimide which is then base hydrolyzed to a polyaspartic acid salt.
    Type: Grant
    Filed: January 28, 1994
    Date of Patent: December 13, 1994
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Abdul R. Y. Meah
  • Polyaspartic acid having more than 50% .beta. form and less that 50% .alpha. form
    Patent number: 5373086
    Abstract: .beta.-Polyaspartic acid having a weight average molecular weight of 1000 to 5000 produced by hydrolysis of anhydropolyaspartic acid exhibits a high degree of calcium carbonate and calcium phosphate inhibition.
    Type: Grant
    Filed: January 26, 1994
    Date of Patent: December 13, 1994
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Kim C. Low, Abdul R. Y. Meah, Anne M. Atencio
  • Composition and method for enhanced fertilizer uptake by plants
    Patent number: 5350735
    Abstract: Water-soluble poly(organic acids) having a molecular size of more than 1,500 Daltons enhance fertilizer uptake and promote plant growth. Particularly suitable for this purpose are the poly(amino acids) such as poly(aspartic acid) and copolymers thereof.
    Type: Grant
    Filed: November 5, 1992
    Date of Patent: September 27, 1994
    Assignee: Donlar Corporation
    Inventors: Alan M. Kinnersley, Larry P. Koskan, David J. Strom, Abdul R. Y. Meah
  • Polyaspartic acid manufacture
    Patent number: 5315010
    Abstract: Polyaspartic acid having a weight average molecular weight of 1000 to 5000 is produced by hydrolysis of anhydropolyaspartic acid that has been produced by condensation polymerization of L-aspartic acid. Conversion in excess of 80 percent is achievable utilizing "temperature vs. time" profiles.
    Type: Grant
    Filed: June 21, 1993
    Date of Patent: May 24, 1994
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Kim C. Low, Abdul R. Y. Meah, Anne M. Atencio
  • Production of polysuccinimide and polyaspartic acid from maleic anhydride and ammonia
    Patent number: 5296578
    Abstract: Production of polysuccinimide by reacting maleic anhydride and ammonia at elevated temperatures. The base hydrolyzed polyaspartic acid product.
    Type: Grant
    Filed: September 18, 1992
    Date of Patent: March 22, 1994
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Abdul R. Y. Meah
  • Polyaspartic acid and its salts for dispersing suspended solids
    Patent number: 5284512
    Abstract: Water soluble salts of a .beta.-polyaspartic acid, i.e., a polyaspartic acid having predominantly beta linkages in the amino acid residue chain thereof, are eminently well suited as dispersants for particulate matter in an aqueous medium.
    Type: Grant
    Filed: February 16, 1993
    Date of Patent: February 8, 1994
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Kim C. Low
  • Manufacture of polyaspartic acids
    Patent number: 5221733
    Abstract: Polyaspartic acid having a weight average molecular weight of 1000 to 5000 is produced by hydrolysis of anhydropolyaspartic acid. Anhydropolyaspartic acid is produced by condensation polymerization of L-aspartic acid. Greater than 80% conversion is achievable utilizing "temperature vs time" profiles.
    Type: Grant
    Filed: February 22, 1991
    Date of Patent: June 22, 1993
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Kim C. Low, Abdul R. Y. Meah, Anne M. Atencio
  • Production of high molecular weight polysuccinimide and high molecular weight polyaspartic acid from maleic anhydride and ammonia
    Patent number: 5219952
    Abstract: A method of producing high molecular weight polysuccinimide and high molecular weight polyaspartic acid. Reacting maleic anhydride with ammonia and further reacting with polymerized polysuccinimide. Hydrolyzing the resultant product to form polyaspartic acid.
    Type: Grant
    Filed: September 18, 1992
    Date of Patent: June 15, 1993
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Abdul R. Y. Meah
  • Polyaspartic acid as a calcium carbonate and a calcium phosphate inhibitor
    Patent number: 5152902
    Abstract: .beta.-Polyaspartic acid having a weight average molecular weight of 1000 to 5000 produced by hydrolysis of anhydropolyaspartic acid, exhibits a high degree of calcium carbonate and calcium phosphate inhibition.
    Type: Grant
    Filed: March 19, 1991
    Date of Patent: October 6, 1992
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Kim C. Low, Abdul R. Y. Meah, Anne M. Atencio
  • Polyaspartic acid as a calcium sulfate and a barium sulfate inhibitor
    Patent number: 5116513
    Abstract: Polyaspartic acid as a calcium sulfate and barium sulfate inhibitor. Generally all forms of polyaspartic acid can be used. .beta.-polyaspartic acids are preferred.
    Type: Grant
    Filed: March 19, 1991
    Date of Patent: May 26, 1992
    Assignee: Donlar Corporation
    Inventors: Larry P. Koskan, Kim C. Low