X-flow B.v.

Hendrik D Roesink

Dirk M Koenhen

Marcellinus H Mulder

Cornelis A Smolders

Gunnar Jonsson

Gede Wenten

Alan Rasmussen

The invention relates to a process for the removal of components causing turbidity, from a fluid, by means of microfiltration, whereby the fluid is beer, wine, fruit juice, bacterial suspension, blood, milk, enzyme suspension, etc. According to the invention, the fluid to be treated is fed across an asymmetric membrane having a pore structure such that the pores on the feed side of the membrane are larger than the nominal pore size and the pores of nominal pore size occur in the cross section toward the permeate side, the filtered off components are back-flushed from the membrane and are subsequently carried away with the fluid. The nominal pore size is usually 0.1-5.0 .mu.m and preferably 0.2-1.0 .mu.m. The membrane may be tubular, flat or capillary. Back-flushing takes place intermittently with a frequency of 1 second to 10 minutes for 0.1-1 second at a counter pressure of 0.5-5 bar. The feed velocity is preferably below 2 m/s and the pressure difference over the membrane is less than 0.5 bar.

Method for the removal of components causing turbidity, from a fluid, by

The invention relates to a method for producing a flat porous product, in which a solution of an elastomeric material is deposited on a temporary substrate and the elastomeric material is coagulated on the substrate from the solution with the aid of a nonsolvent, wherein the surface of the substrate has an adhesion to the coagulating elastomer which is such that, after coagulation, the elastomeric flat product can be removed from the substrate without damage and the side (macroporous zone or bottom layer) of the elastomeric flat product facing the substrate possesses pores having a diameter in the region of 20-200 .mu.m and has a porosity of more than 75%, a flat product which can be obtained according to this method for use as wound covering material and a method for treating wounds therewith.

Method for producing a flat porous product

The invention relates to a process for preparing a microporous membrane, starting from a mixture of at least a hydrophobic polymer and a hydrophilic polymer, by dissolving these polymers first in a suitable solvent or mixture of solvents and subsequently by coagulating in a coagulation bath. According to the invention a more or less hydrophilic membrane is prepared by removing the membrane so obtained from the coagulation bath and subsequently by leaching at least a part of the hydrophilic polymer from the matrix, alternatively followed by hydrophobization. Said leaching of the hydrophilic polymer occurs by treatment of the membrane with an oxidizing/hydrolizing agent. The invention furthermore comprises microporous membranes, flat or tubular or in the form of hollow fibers, having a good chemical resistance and good mechanical strength.

Process for preparing a microporous membrane and such a membrane

This invention relates to a process for the preparation of hydrophilic membranes by coagulation of a solution of at least one hydrophobic polymer and at least one hydrophilic polymer in a suitable solvent medium in a coagulation medium. The process according to the invention is characterized in that hydrophilic microfiltration and/or ultrafiltration membranes are prepared by cross-linking the hydrophilic polymer which is present in or on the obtained membrane matrix after the coagulation in an essentially non-swollen state and fixing same as such in or on the polymer matrix. Advantageously the solvents and the undesirable components of the coagulation medium are removed whereby the hydrophilic polymer is converted into an essentially non-swollen state prior to cross-linking. The removal of the undesirable components from the membrane takes place by means of a non-solvent for the hydrophilic polymer according to the invention. Finally, the invention relates to hydrophilic microfiltration- and/or ultrafiltration membranes, flat or tubular of a hollow fiber structure.

Growing community of inventors

Hengelo, Netherlands

Hendrik D Roesink