DE3049247A1 - DIALYSIS MEMBRANE FILM - Google Patents

Description

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Dialysis membrane filament

Akzo GmbH Wuppertal

The invention relates to one of two or more firmly adhered to one another Layers of dialysis membrane in Hollow filament shape with a continuous cavity and wall thickness of cellulose that is constant over the circumference and length, which was regenerated from cuoxam solutions.

In the German patent application P 28 48 601.3 is a Dialy £; «. MiK'iiibr.in described, which regenerates from cuoxam solutions, was, in the form of oinos RohlJ'adons with continuous Cavity un-1 is characterized in that the thread cross-section is designed perpendicular to the thread axis so that the wall of the hollow threads along their circumference is at least one

ORIGINAL INSPECTED

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! times continuously increases up to a maximum thickness and

• decreases to a minimum thickness.

j From the German Offenlegungsschrift DE-OS 27 05 733 and

j DE-OS 27 05 735 are composed of two or more layers

i built dialysis membranes in hollow fiber, flat film and

i known tubular film form. Due to the multi-layered

'_ the formation of a greater leak resistance of the membranes

j aims. In addition, the multilayer design allows the

- Membrane, if necessary, chemical anchoring of loading

t agents, such as heparin.

j It has been shown that in the case of the first-mentioned patent application

j message excellent permeabilities can be achieved. Unfortunately

I "" * these eccentric hollow fibers have an increased

• driving of leaks in the thin wall area.

I The object of the present invention was to provide a dialysis sem-

branch in hollow filament form with a continuous cavity so that

j stalten that the increased risk of leaks in the thin

\ Wall area is greatly reduced and the advantages of the ex-

! central hollow fiber are retained.

j This task is solved with the dialysis membrane of the introduction

j mentioned type, which is characterized in that min-

the layer thickness at least in the case of two layers along their circumference at least once continuously up to a maximum

i increases in thickness and decreases to a minimum thickness, where

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The layer thicknesses at every point of the circumference add up to a wall thickness that is constant along the circumference.

in particular, the dialysis membrane according to the invention can be designed in such a way that when the layer thickness is increased and decreased several times, the areas with maximum thickness and the areas with MLnimaldickness approximately the same distances on the circumference exhibit.

It is advantageous if all areas with a maximum thickness or with a minimum thickness within a layer are identical to one another are thick.

For these forms of embodiment, corresponding spinnerets for the production of the invention can be created in a particularly simple manner Design dialysis membranes, especially when preferably all areas with maximum thickness or minimum thickness each layer are equally thick among each other.

General because of the clear flow ratio se circular flow cross-sections are preferred. This also results in the dialysis membranes according to the invention in the form of carbon fiber, a special form in that the layer thickness of the layers of the hollow fiber and decreases so that thread circumference and cavity circumference are essentially circular and the centers of these coincide with both circles.

Hon LL'ädcn Tür Dialyscmombranen generally have one Aui'ondurchmesccr from 100 to 1,000 to with wall thicknesses of approx. 10 to 100 um.

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ORIGINAL INSPECTED

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In the hollow fiber dialysis membrane according to the invention, the minimum thickness of a layer is preferably 2 to 9 μm the ratio of maximum thickness to minimum thickness is preferably 2 to 6.

The dialysis membranes according to the invention can be prepared in an analogous manner according to the method described in DE-OS 27 05 733 getting produced. It has been shown that they can also be used in an analogous manner according to that in the German patent application P 29 06 576.7 described ancestors hcr:.; Tol.lbar are.

The advantage of the increased permeability, as it is achieved with eccentric hollow filaments, can then be particularly evident well maintained when the dialysis membrane filaments according to the invention be produced by a method which is characterized in that two or more Cellulosecuoxam solutions through at least two separately fed slots adapted to the desired hollow filament shape and a spinneret having a central bore through which a liquid forming the cavity is passed squeezed out and passed into a precipitation bath, the concentrations of cellulose of the two or more Ccllulosecuoxamlösungen are different.

The cellulose concentration of the cellulose cuoxam solution is preferably which is fed to the slot adjacent to the central bore, higher than the cellulose concentrations of the other cuoxam solutions.

In an embodiment of the method according to the invention, the cellulose concentration of the cellulose suoxam solutions

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between 5 and 12 wt .-%, based on the weight of the Cuoxam solutions.

Figure 1 shows the cross-section of a Ui a 1 y: jernonibran according to the invention, the layer thickness of the layers 2, 3 of the hollow fiber adnns 1 £ jo increasing and decreasing, that the thread unil.imj and ileal space are essentially circular and the centers of the inner and outer match the outer circle.

FIG. 2 shows the cross section of another dialysis membrane according to the invention with threefold increase and decrease in layer thickness, the areas with maximum thickness and the areas with minimum thickness each having approximately the same spacing on the circumference. Here too, 1 denotes the hollow fiber as such and the layers denote 2, 3.

The invention is further developed with the aid of the following examples explained:

example 1

Manufacturing example

Through a hollow filament spinning nozzle with two separately fed, the desired hollow filament shape (Figure 1) adapted, slots and a central bore for the cavity forming Liquid (isopropyl myristate) were two Cuoxam solutions in a precipitation bath, which contained 125 g / l sodium hydroxide in water, extruded. The cuoxam solution that was fed to the inner slot had the following composition: 9% by weight Cellulose, 4 wt .-% Cu as basic copper sulfate and 7 wt .-% NII and water.

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EAD ORIGIMAL |

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A cuoxam solution was applied to the outer slot of the hollow filament spinning nozzle with the composition 6 wt .-% cellulose, 4 wt .-% Cu as basic copper sulfate, 7 wt .-% NH, and water, fed -

After washing out the hollow fiber with dilute sulfuric acid and water and drying, the cross-section corresponded

of the hollow fiber of Fig. 1 and the wall thickness was 16 µm, the maximum thickness of each layer being 12 µm and the minimum thickness 4 um. The diameter of the hollow filament was 230 µm.

Correspondingly, a hollow filament spinning nozzle adapted an eccentric hollow filament cross-sectional shape Slit and a central bore, a Cuoxam solution with the composition 9 wt .-% cellulose, 4 wt .-% Cu as basic copper sulfate, 7 wt .-% NH ^ and Wascor, through the slot and a cavity-forming liquid through the central hole in a precipitation bath, respectively 125 g / l sodium hydroxide and water extruded. After the usual washes in dilute sulfuric acid and water and drying, a hollow filament was obtained, the inner diameter of which was 215 µm, the minimum wall thickness of which was 6 µm and the maximum wall thickness of which was 26 µm. This comparative hollow thread corresponded to such a thread in accordance with German Offenlegungsschrift 28 48 601.

Example 2

Check for leak tightness

Behind the drying zone of the hollow filament spinning machine, which is used for

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the experiments for example 1 had been used, a pair of rollers was arranged over which the threads were guided with 180 ° wrap before they were wound onto bobbins. During the period for the production of 250 bobbins each 10 km long, corresponding to 4,000 m ^2, the stains were counted which were created when a leak overflowed the rollers because a drop of the cavity-forming liquid had leaked. The rollers were coated with rubber with a Shore hardness of more than 300 °. The stain that appeared in each case was clearly visible and was wiped off with ethanol after counting.

In the inventive hollow fiber leakage at 1,000 m ² hollow fiber surface was found during the comparison was a leak hollow fiber at 90 m ^a hollow fiber surface determined. The leakage frequency was thus reduced to less than 1/10 in the case of the hollow thread according to the invention, compared to the comparison hollow thread.

Example 3

Use of the dialysis membrane filament for hemodialysis From the hollow filament according to the invention and the comparative hollow filament Hollow fiber bundles were produced, which were installed in a hollow fiber test dialyzer and under standard conditions have been checked.

The test method is described in "Evaluation of Hemodialyzers and Dialysis Membranes" Report of a study group for the artificial kidney - chronic urema program 1977;

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Elias Klein et al. US Department of Health Education and Weifare. Bethesda, Maryland 20014 Publ. NIH 77-1294.

The dialysis membranes produced according to Example 1 were compared. The solution flow was 200 ml / min and the dialysate flow was 500 ml / min. The vitamin B 12 tolerance was 44 ml / min for both the hollow thread according to the invention and the comparison hollow thread. The ultrafiltration rate was determined to be 4.0 ml / hm ² * mm Hg for both hollow fiber types.

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Claims (10)

Γ Π A3GW31970 patent claims 1. From two or more firmly adhering layers existing dialysis membrane in the form of a hollow thread with a continuous cavity and constant over the circumference and length Wall thickness, made of cellulose which has been regenerated from Cuoxane solutions, characterized in that at least with two layers along their circumference Layer thickness increases at least once continuously up to a maximum thickness and down to a minimum thickness decreases, the layer thickness at every point on the circumference becoming constant along the circumference Add wall thickness. 2. Dialysis membrane according to claim 1, characterized in that with multiple increases and decreases in the layer thickness Areas with maximum thickness and the areas with minimum thickness each have approximately the same spacing on the circumference exhibit. 3. Dialysis membrane according to claims 1 to 2, characterized in that that all areas with maximum thickness or with minimum thickness within a layer below one another are equally thick. 4. Dialysis membrane according to claim 3, characterized in that all areas with maximum thickness or minimum L J ■ I ^ ...., .., INSPECTED r π _ 2 - A3GW3197O thickness of each layer are equally thick among each other. 5. dialysis membrane according to claim 1, characterized in that the layer thickness of the layers of the hollow fiber so increases and decreases that thread circumference and cavity circumference are essentially circular and the center points both circles agree. 6. Dialysomenibran made of cellulose, according to claims 1 to 5, characterized in that the minimum thickness 2 to 9 µm. 7. dialysis membrane made of cellulose according to claims 1 to 6, characterized in that the ratio of maximum thickness to minimum thickness is 2 to 6. 8. Process for the production of a dialysis membrane in the form of a hollow thread according to claims 1 to 7, characterized in that two or more cellulose suoxam solutions by at least two separately fed slots adapted to the desired hollow filament shape and a central bore through which a liquid forming the cavity is passed Spinneret squeezed out and passed into a precipitation bath, the concentrations of cellulose of the two or more cellulose suoxam solutions are different. ORIGINAL INSPECTED - 3 - A3GW3197O 9. The method according to claim 8, characterized in that the cellulose concentration of the cellulosecuoxam solution, which is fed to the slot adjacent to the central bore is higher than the cellulose concentrations the other cuoxam solutions. 10. The method according to claims 8 to 9, characterized / that the cellulose concentration of the cellulose suoxam solutions is between 5 and 12% by weight.