Akzo N.v.

Helmut Schulze

Michael Pelger

Walter Brodowski

Hans G Zengel

Michael Diamantoglou

Ulrich Baurmeister

Gustav Dunweg

Joachim Behnke

Gerhard Wick

Werner Henne

Peter Hentschel

Franciscus J Huntjens

Jan A Schutijser

Helmut Brahm

Ernst Berg

The invention relates to a process for obtaining extractive-material-reduced cellulose with a low LAL reaction, wherein cotton linters or wood pulps, subsequent to the customary digesting treatment, are subjected for 1 to 10 hours to hydraulic washing with water, lye with a concentration of less than 5 g/l alkali content, or with a diluted acid containing less than 5 g/l acid at temperatures of 120.degree. to 180.degree. C. and under a pressure of 2 to 20 bar. The resulting cellulose is used for the manufacture of hemodialysis and/or hemofiltration membranes in the form of flat membranes, tubular membranes or hollow filaments by regeneration of a cellulose solution containing the extractive-material-reduced cellulose with a low LAL reaction. The regeneration may be effected from solutions of cellulose cuoxam, cellulose xanthate, or solutions of cellulose in tertiary amine oxide or in an LiCl-containing solvent.

Process for producing extractive-material-reduced cellulose

The invention relates to a dialysis membrane of regenerated cellulose and to a process for its production. Isocyanate prepolymers with an average molecular weight of 300 to 50,000, which are soluble in organic solvents other than solvents reacting with isocyanate groups and dissolving cellulose, are bound chemically at least to one membrane surface of the dialysis membrane. The dialysis membrane of the present invention substantially eliminates the symptoms of leukopenia and complement activation.

Cellulose dialysis membrane with improved biocompatibility

The invention relates to a method for the production of a dialysis membrane of regenerated cellulose. Isocyanate prepolymers with an average molecular weight of 300 to 50,000, which are soluble in organic solvents other than solvents reacting with isocyanate groups and dissolving cellulose, are bound chemically at least to one membrane surface of the dialysis membrane. The dialysis membrane made by the process of the present invention substantially eliminates the symptoms of leukopenia and complement activation.

Production of cellulose dialysis membrane with improved biocompatibility

A dialysis membrane used for hemodialysis having a structure comprised of flat films, blown films or tubular threads of substitution-modified cellulose, in which the effects of complement activation and leukopenia are clearly reduced. The average degree of substitution of the modified cellulose is 0.02 to 0.07. Dialysis membranes, which have proven successful within the scope of the invention, contain modified cellulose, having a structure represented by the formula cellulose-Z, wherein Z represents the group --R'--X--Y.

Dialysis membrane of modified cellulose with improved biocompatibility

Embedding mass of polyurethane produced on the basis of castor oil, and a method for its production, wherein an aromatic diisocyanate is reacted with a mixture of castor oil and trimethylolpropane into an NCO-group displaying pre-adduct, the pre-adduct being mixed for network polymerization with castor oil or a mixture of castor oil and trimethylolpropane, and after embedding the mixture is hardened in the presence of catalyst, thereby characterized in that a titanium alkylate compound is used as catalyst in amounts from 7 to 700 ppm, calculated as elemental titanium. Preferably, the catalyst is a titanium tetraalkylate; in particular titanium tetrabutylate. Also, a titanium magnesium hexaalkylate may be used as titanium alkylate compound; preferably, titanium magnesium hexabutylate. Preferably the catalyst is present in amounts from 40 to 140 ppm, calculated as elemental titanium. The embedding mass may be used for the embedding of membranes, particularly in artificial organs, especially in the form of hollow filaments, tube foils or flat foils. They may be used for selectively working dialysators, including selectively working hemodialysators, and other arrangements for the detoxification of blood. The embedding is performed according to the casting process, preferably the centrifuge casting process.

Embedding mass of polyurethane

Polyurethanes prepared from macrodiols with an average molecular weight between about 800 and 4000, lower molecular weight chain extenders with at least two labile hydrogens, and cyclohexane-1,4-diisocyanate with a trans-isomer content of at least 90%, are described. These polyurethanes exhibit exceptional mechanical properties, high softening temperatures, and remarkable stability to light and to many common solvents. Methods for preparation of the novel polyurethanes, as well as for their use, are also disclosed.

Polyurethanes from trans-cyclohexane-1,4-diisocyanate

A process for the production of polyurethane solutions by reaction of a diisocyanate with a mixture of a glycol and a polymer bearing terminal hydroxy groups in a solvent medium under certain prescribed conditions. The resulting polyurethane solutions are especially valuable as impregnants or coating agents for textile substrates, for example in the preparation of a microporous synthetic leather.

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Wuppertal, Germany

Helmut Schulze