Cellulose acetate hollow fiber and method for making same
AssigneeCordis Dow Corp.
InventorsMichael J. Kell, Robert D. Mahoney
Life of this patent
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Abstract
An improved cellulose acetate semi-permeable hollow fiber suitable for use in artificial kidneys and a process for making same.
Claims8
A cellulose acetate hollow fiber having an internal diameter in the range of about 100 to about 350 microns and a wall thickness in the range of about 20 to about 60 microns, said wall having a selective permeability when used in hemodialysis for water and solutes to be removed from blood represented by an ultrafiltration coefficient K.sub.UFR in the range of about 2 to about 6 milliliters per hour per square meter per millimeter of mercury and a urea coefficient K.sub.UREA in the range of about 15.times.10.sup.-3 to about 45.times.10.sup.-3 centimeters per minute, said fiber characterized by the concurrent capability of separating urea from blood and water from blood at rates represented by a minimum ratio of the coefficients K.sub.UREA /K.sub.UFR of 3 to 1.times.10.sup.-3.
A cellulose acetate hollow fiber having an internal diameter in the range of about 100 to about 350 microns and a wall thickness in the range of about 20 to about 60 microns, said wall having a selective permeability when used in hemodialysis for water and solutes to be removed from blood represented by an ultrafiltration coefficient K.sub.UFR in the range of about 2 to 6 milliliters per hour per square meter per millimeter of mercury, a urea coefficient K.sub.UREA in the range of about 15.times.10.sup.-3 to about 45.times.10.sup.-3 centimeters per minute, and a creatinine coefficient K.sub.creatinine in the range of about 13.times.10.sup.-3 to about 27.times.10.sup.-3 centimeters per minute, said fiber characterized by the concurrent capability of separating urea from blood and water from blood at rates represented by a minimum ratio of the coefficients K.sub.UREA /K.sub.UFR of 3 to 1.times.10.sup.-3.
A cellulose acetate hollow fiber having an internal diameter in the range of about 100 to about 350 microns and a wall thickness in the range of about 20 to 60 microns, said wall having a selective permeability when used in hemodialysis for water and solutes to be removed from blood represented by an ultrafiltration coefficient K.sub.UFR in the range of about 2 to 6 milliliters per hour per square meter per millimeter of mercury, a urea coefficient K.sub.UREA in the range of about 15.times.10.sup.-3 to about 45.times.10.sup.-3 centimeters per minute, a creatinine coefficient K.sub.creatinine in the range ofabout 13.times.10.sup.-3 to about 27.times.10.sup.-3 centimeters per minute and a Vitamin B 12 coefficient K.sub.B12 in the range of about 2.times.10.sup.-3 to about 5.times.10.sup.-3 centimeters per minute, said fiber characterized by the concurrent capability of separating urea from blood and water from blood at rates represented by a minimum ratio of the coefficients K.sub.UREA /K.sub.UFR of 3 to 1.times.10.sup.-3.
A process for making cellulose acetate hollow fibers which comprises the steps of
- (1) providing an intimate mixture of about 41 to about 50 weight percent cellulose acetate, about 2 to about 20 weight percent glycerine, and about 30 to about 57 percent polyethylene glycol having a molecular weight in the range of about 150 to about 600,
- (2) fabricating hollow fibers from a molten mass of said mixture,
- (3) cooling said fibers,
- (4) cold drawing said fibers an amount in the range of about 2% to about 20% of said cooled fiber length,
- (5) leaching said fiber to remove therefrom said polyethylene glycol and said glycerine, and
- (6) replasticizing said fiber with glycerine and thereafter drying same.
Dependencies are inferred from the claim text.