Patents by Inventor Lothar Steinfeld

Lothar Steinfeld has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for manufacturing cellulose acetate membranes
    Patent number: 5505890
    Abstract: A dialysis membrane in the form of a hollow fiber with a continuous internal cavity is made of cellulose acetate or a cellulose acetate derivative. The membrane has a maximum screen coefficient of 0.04 for albumin with a molecular weight of 68,000. A dialysis membrane in the form of a hollow fiber with a continuous internal cavity may be made in a process using a spinning solution containing an organic carboxylic acid and a cavity-forming liquid. Modification agents and/or water are optionally added and the solution is extruded through a spinneret suitable for the manufacture of hollow fibers. The precipitation of the resultant dialysis membrane and the usual further aftertreatment take place in a precipitation bath. The organic carboxylic acid preferably is acetic acid and the precipitation bath preferably is a dilute acetic acid.
    Type: Grant
    Filed: October 19, 1994
    Date of Patent: April 9, 1996
    Assignee: Akzo N.V.
    Inventors: Gustav Duweg, Lothar Steinfeld, Wolfgang Ansorge
  • Cellulose acetate membranes
    Patent number: 5387345
    Abstract: A dialysis membrane in the form of a hollow fiber with a continuous internal cavity is made of cellulose acetate or a cellulose acetate derivative. The membrane has a maximum sieving coefficient of 0.04 for albumin with a molecular weight of 68,000. A dialysis membrane in the form of a hollow fiber with a continuous internal cavity may be made in a process using a spinning solution containing an organic carboxylic acid and a cavity-forming liquid. Modification agents and/or water are optionally added and the solution is extruded through a spinneret suitable for the manufacture of hollow fibers. The precipitation of the resultant dialysis membrane and the usual further aftertreatment take place in a precipitation bath. The organic carboxylic acid preferably is acetic acid and the precipitation bath preferably is a diluted acetic acid.
    Type: Grant
    Filed: May 19, 1993
    Date of Patent: February 7, 1995
    Assignee: AKZO NV
    Inventors: Gustav Dunweg, Lothar Steinfeld, Wolfgang Ansorge