Akzo N.v.

Christoph Josefiak

Michael Diamantoglou

Joachim Behnke

Helmut Magerlein

Friedrich Wechs

A new water-swellable composition of a gelling agent based on hydrolyzed homo- or copolymers of acrylonitrile and of an inert metal oxide was synthesized. In the process, 1 to 22% of the nitrile groups were saponified to amide groups and 99 to 78% to alkali-metal salts. The obtained composition had a spongy structure and was characterized by high values with regard to both swelling capacity and swelling rate. Therefore it is particularly suitable for diaper manufacture and for agricultural use.

Water-swellable composition, synthesis and use thereof

In a process for the production of linear segmented polyurethane by simultaneous reaction of macrodiols, low-molecular diols as chain-lengthener and aromatic diisocyanate, in a solvent in the presence of catalyst, and in the presence of catalytic amounts of a magnesium or calcium salt, an aromatic carboxylic acid macrodiol, monomeric, lower-molecular diol and aromatic diisocyanate are reacted, the macrodiol being used in such amounts as to adjust in the prepared polyurethane a weight ratio of soft segment to hard segment of about 4:1 to 1:4. Preferred embodiments include reaction at temperature from about 70.degree. to 120.degree. C.; use of an inert solvent; and having the concentration of starting material amount to about 10-40% by weight relative to the mixture of starting material and solvent. Also provided are polyurethanes obtained according to this process, having a molecular non-uniformity from 2 to 7. Preferred embodiments include that the polyurethane have an average molecular weight from 60,000 to 250,000. The polyurethanes are useful for the production of membranes, specifically those to be used for sterile filtration or blood oxygenation.

Linear segmented polyurethane and process for its production

Porous shaped bodies are disclosed, and an apparatus and method of their production by extruding a homogeneous, single-phase liquid mixture of polymer and mixing partner liquid at the temperature of mixture preparation through a nozzle downwardly with a linear velocity v.sub.1 into a cooling liquid that dissolves the polymer insubstantially or not at all at the cooling temperature, the cooling liquid being provided from entry of the extruded mixture until at least the point of start of solidification thereof in a substantially vertically arranged tubular zone surrounded by a wall, velocity v.sub.2 of cooling liquid in this zone being less than v.sub.1. The cooling liquid is preferably contained in a U-shaped tube and its level is controllable by dosing at entry and/or exit points.

Porous shaped bodies, and method and apparatus for the production thereof

Porous bodies, particularly membranes in the form of hollow filaments, are produced by heating a polymer above the upper critical temperature T.sub.c in a mixture of two compounds A and B, liquid and miscible at the dissolving temperature, whereby the employed mixture (polymer, compounds A and B) in liquid aggregate state displays a miscibility gap, the compound A is a solvent for the polymer and the compound B, which preferably is a non-solvent or a swelling agent for the polymer, raises the phase separation temperature of a solution composed of the polymer and compound A. After the dissociation, the components A and/or B if necessary are extracted. Through use of non-toxic substances such as e.g. edible oil as compound A and castor oil as compound B, bodies are obtained which are non-toxic and unobjectionable for use in medical areas and in the foods industry, among others.

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Kleinwallstadt, Germany

Christoph Josefiak