DE3002438C2 - Selectively permeable membrane - Google Patents

Description

characterized,

f) that the washed membrane is 1.3 to 2.2 times in the transverse direction and 0.9 to 1.3 times in the longitudinal direction stretches,

g) the moisture content of the membrane during stretching is at least 100% by weight is based on the weight of the cellulose,

h) maintain the applied stretching tension at least as long during drying until a moisture content of OK% is reached.

2. Membrane according to claim 1, characterized in that the washed membrane in Stretches 1.5 to 2 times transversely.

3. Membrane according to claim 1 or 2, characterized in that the washed membrane in the longitudinal direction 1.0 to 1.2 times stretched.

4. Membrane according to one of claims 1 to 3, characterized in that the moisture content holds the membrane in the range of 100 to 300% during stretching.

The invention relates to selectively permeable membranes made from regenerated cuoxam cellulose.

Significant advances have recently been made in mass separation using a high molecular weight membrane made for recovery in reverse osmosis, ultrafiltration, dialysis etc. These membranes are used extensively for technical and medical purposes.

The membranes used for these purposes can be made from a wide variety of materials including regenerated cellulose, cellulose derivatives, acrylonitrile polymers, polyvinyl alcohols and various other synthetic high molecular weight materials. Of these materials is regenerated cellulose is particularly suitable because it is a naturally occurring high molecular weight material and can be used safely and safely in or with the living body. Regenerated cellulose membranes are therefore particularly suitable for medical applications, e.g. B that Blood dialysis, blood filtration and ultrafiltration for the production of sterile water for medical professionals Treatments, suitable. Membranes that are used for these medicinal purposes must be for valuable components of the blood, e.g. B. erythrocytes, leukocytes and proteins, while impermeable it is desirable that they apply to water and relatively low molecular weight substances such as urea and Creatinine in the blood are extremely permeable. The well-known membranes made of regenerated cellulose, the from a viscose solution or a Cuoxam-Cellulose-T solution are generally satisfactory, because they have a very even and dense structure and for high molecular substances such as Proteins are impermeable. However, it is a disadvantage that it is also applicable to medium molecular weight substances from, for example, 500 to 5000 are slightly permeable.

For membranes used for blood filtration and ultrafiltration, it is desirable that they are extremely permeable to water, especially under pressure. Membranes made from ordinary regenerated Celluloses, however, are not always very satisfactory in this regard, but inevitably require a large surface for filtration.

A solution to these problems could be the use of a membrane with the smallest possible thickness represent. It is true that the permeability of the membrane for water and other substances is greater, the more The thickness of the membrane is smaller. However, there are limits to the effectiveness of this solution because it is Decreasing the thickness of the membrane decreases its strength accordingly. It is also known to improve the permeability of a selectively permeable membrane, the conditions of membrane formation, z. B. the composition and concentration of the solvent and the coagulant to be used to regulate and thereby to form a membrane with an asymmetrical structure, which consists of a very thin, dense layer and a porous layer with pores of a few μm in diameter. To the Manufacture of a membrane from regenerated cellulose with such an asymmetrical structure from a Viscose solution or cuoxam cellulose solution, as they are commonly used in industry, must however, a special substance in the cellulose solution

dispersed and removed after the membrane is formed. This procedure requires a very laborious one Washing stage to all these substances like kerosene, light oil and liquid paraffin necessary for the formation Numerous pores in the membrane are used to completely remove it. This procedure is particular for the production of membranes that are used for medical applications, for example for the Blood dialysis and filtration are used, inappropriately, since even a trace of additives of this kind, the

so remain in the membrane can be detrimental to the human body.

The object of the invention is to provide a new cuoxam cellulose membrane with a negative wet elongation rate in the transverse direction of the membrane and with one determined by the X-ray diffraction pattern Orientation degree of 70% or less and high wet burst strength.

The above-mentioned object is achieved by the selectively permeable membranes according to the above claims solved.

The invention is explained below with reference to the figures.

F i g. 1 shows a schematic representation of the fine structure of a known membrane made from regenerated Cellulose;

F i g. FIG. 2 shows a representation similar to FIG. 1 and illustrates the fine structure of a according to FIG Cellulose membrane made in the invention;

F i g. 3 schematically shows, as a side view, a method for producing a flat membrane according to the invention;

F i g. 4 shows a stretching device as a top view, which can be used in the method according to the invention;

FIG. 5 shows a schematic side view of a further embodiment of the method according to FIG Invention;

Fig. 6 is a schematic side view showing a Shows embodiment of a dryer which can be used for the purposes of the invention.

The following are the presently preferred embodiments of the invention shown in the figures are shown, described in detail. The invention covers not only flat membranes, but also tubular membranes and obtained by cutting open tubular membranes flat membranes.

The membrane of the invention made of regenerated Cuoxam cellulose has a negative wet elongation in Cross direction, however, the wet elongation is not less than -15.0%. The term used here “Transverse direction” denotes the direction regardless of whether the membrane is flat or tubular perpendicular to the longitudinal or machine direction. The term used here for a membrane “Longitudinal direction” denotes the direction perpendicular to the transverse direction defined above. According to the Invention, a wet elongation of the membrane in the transverse direction of about -2.0 to about -15.0% preferred. A well-known membrane made of regenerated Cuoxam cellulose, which is used as a selectively permeable membrane is used has a longitudinal wet elongation of -10 to 0% and a transverse wet elongation from 0% to 10%.

A membrane with a negative wet elongation in the transverse direction constitutes a selectively permeable membrane with improved properties, but it is more appropriate that their wet elongation in the longitudinal direction is less than 0%.

The membrane should have a degree of orientation from 0% to about 70%, preferably from 0% to about 65% exhibit. The degree of orientation in this area significantly increases the wet burst strength of a selective permeable membrane and allows the thickness of the membrane to be reduced while increasing its strength a height required for practical use is maintained. A membrane with a The degree of orientation from 0% to about 65% has a particularly high wet burst strength

The selectively permeable membrane according to the invention preferably has a thickness of about 5 to 30 μητ With a thickness exceeding 30 μητ, the Permeability of the membrane is reduced to such an extent that it is selectively permeable for use as a membrane Membrane is unsuitable. It is known that reducing the thickness of a membrane increases its permeability and makes it possible to obtain a useful membrane for selective permeation. It however, it is very difficult to produce a thin, yet sufficiently strong membrane. It was so far impossible to have a thickness of less than about 10 μm a known membrane made of regenerated Cuoxam cellulose, which is used for selective permeation will achieve. According to the invention, however, it is possible to use a membrane with approximately double Naßfestisrkeit all known membranes to produce and therefore their thickness without sacrificing strength up to down to 5 μπι to decrease.

The membrane according to the invention is suitable as a selectively permeable membrane for the most diverse Areas of mass and material separation, for example for the concentration or filtration of fine particles Substances through technical dialysis and ultrafiltration, however, make their numerous advantages special noticeable when used for hemodialysis, blood filtration

ίο or similar purposes are used. She is not in least permeable to valuable components of the blood, e.g. B. erythrocytes, leukocytes and proteins, but extremely permeable to water, urea, creatinine and other low-molecular substances.

In contrast to all known membranes made from regenerated cellulose, the membrane has an extremely high quality greatly improved degree of permeability for substances with an average molecular weight of about 500 to 5000. The membrane according to the invention further comprises a

ίο very high wet burst strength.

These outstanding features of the membrane according to the invention are presumably close to one another Connection with the fine structure of cellulose. The orientation of the cellulose molecules and the degree of stretch of the molecular chains are very characteristic of the membrane according to the invention. In particular, the Structure of the non-crystalline part of the membrane, which has a significant effect on its mass permeability has to be extremely different from that of all known membranes made from regenerated cellulose to watch. Cellulose usually consists of crystalline and amorphous parts. Your molecular chains extend through crystalline and amorphous parts, whereby so-called fringe micelles are formed. Cellulose as a whole has a structure in which the molecular chains in the amorphous divider, a fine network with the Crystal micellar cells that have a very strong intermolecular structure Have bond, form. It is therefore assumed that the permeability of a cellulose membrane,

d. H. the penetration and diffusion of the mass through the membrane, on the coarseness or density of the Network in the amorphous part depends in the sense that the membrane with increasing openings of the Network has improved permeability. The network openings in the membrane structure can can be enlarged if the membrane is uniform both in the longitudinal direction and in the transverse direction is stretched around the molecular chains in the amorphous part both in the longitudinal direction and in the transverse direction enough to stretch. The membrane is thus biaxially stretched, it being assumed that the molecular chains and the crystal micelles in the cellulose are stretched in the longitudinal direction and transverse direction in the membrane, without taking a particular direction as a whole.

This is described below using a typical example.

Fig. 1 is a typical view showing the fine structure of a known regenerated cellulose membrane, while Fig. 2 shows a similar view like FIG. 1 and the fine structure of a according to the invention cellulose obtained. In Fig. 1 and F i g. 2 indicate the rectangular areas Kristalimizellen and the wavy lines connecting the crystal micelles represent chains of molecules in the cellulose. In of the known cellulose membrane, all molecular chains are in the crystal micelles and amorphous parts in the aligned essentially lengthways, and the molecular chains in the amorphous parts are sharp

kinked and form small openings in the network. In the fine structure of the cellulose membrane shown in FIG according to the invention, the molecular chains in the crystal micelles and amorphous parts are both in Longitudinal as well as transverse in the plane, without any particular alignment as a whole and the molecular chains are fully stretched and form greatly enlarged network openings. A membrane with such a fine structure is extremely permeable to substances and shows when they are is moistened, a tendency to shrink both longitudinally and transversely. The membrane has a negative wet elongation and thus a high wet tensile strength.

In the membrane according to the invention, an adsorbent, etc. can advantageously be incorporated to give it improved properties. For example, an adsorbent, z. B. activated carbon, activated alumina or a zeolite, are incorporated into the membrane, or a Layer of such an adsorbent can be inserted between two membranes to ensure the selective To improve the permeability of the membrane or membranes.

A membrane used for blood dialysis or filtration can be treated with an anticoagulant or with a two-layer structure of an anticoagulant layer and a layer of ordinary regenerated Cuoxam cellulose can be formed.

A method related to the Manufacture of a flat membrane described. F i g. 3 is a side view schematically simplified Process for making a flat membrane from a cuoxam cellulose solution illustrated.

In the case of the in FIG. 3 plant shown is a solution of Cuoxam cellulose through a T-shaped Nozzle 1 is extruded into a coagulation bath 2, which consists of 10% by weight sodium hydroxide solution in this Description, all percentages are by weight unless otherwise specified. The Cuoxam cellulose solution is coagulated while it is by a drive roller arranged at the bottom of the coagulating bath 2 3 is pulled through the bathroom. A flat membrane 4 formed by coagulating the solution is passed through dewatering rollers 5 and then introduced into two Regenerierur.gsbäder 6 and 7, the contain about 5% sulfuric acid. 8 with a drive roller is referred to, with which a roller 9 through a chain, not shown, is connected. After leaving the regeneration baths, the flat Membrane introduced into two water baths 10 and 11 and mii water gui washed. If necessary, the The membrane is also introduced into a bath 12 containing a plasticizing agent, e.g. B. glycerine or propylene glycol, It is then passed through dewatering rollers 13 The flat membrane is then in a Dryer 14 introduced During coagulation, regeneration and during washing, the flat membrane 4 over a plurality of drive rollers 8 and rollers 9, which rotate with rollers 8 are connected, transported The rollers 8 and 9 are at the top and bottom of each coagulation, Regeneration and washing bath arranged These rollers always exert a force on the membrane 4, pulling the membrane in the machine direction or the lengthwise direction. When the membrane passes through the running individual baths, the solution in the bath is set in motion, with a resistance to the Movement of the membrane is generated and a stretching effect is thereby exerted on it. Based on these Stretching effects, the membrane is usually stretched in the longitudinal direction by about 5 to 20%. In In the transverse direction, the membrane experiences an overall shrinkage as it passes through the various work stages from 20 to 40%. Their shrinkage reaches its maximum in the regeneration baths

ίο and is 10 to 30%.

The membrane left in the moist state after the work steps described above regenerated cuoxam cellulose is then dried under tension. This measure of drying under tension is made by pulling the membrane 1.3 to 2.2 times, preferably 1.5 to 2.0 times is stretched in the transverse direction. If it is stretched less than 1.3 times in the transverse direction, no membrane is formed obtained with sufficient permeability for water, urea and other substances. It is inexpedient to stretch more than 2.2 times, as the membrane often tears. Preferably the membrane is at least 1.5 times stretched, increasing their permeability to water, urea and other substances, in particular those of medium molecular weight, dramatically improved and using a selectively permeable membrane excellent properties is obtained. However, it is advisable not to stretch more than 2.0 times, to ensure stable and effective membrane manufacture according to the invention.

The membrane according to the invention is stretched 0.9 to 1.3 times in the longitudinal direction. By at least 0.9 times stretching in the longitudinal direction with a maximum shrinkage of 10% becomes slack in the membrane, caused by the transverse folds, essentially eliminated so that a high quality membrane can be manufactured. However, it is advisable to stretch more than 1.3 times Avoid the longitudinal direction in order to form a perfect membrane without running in the longitudinal direction To ensure wrinkles or local cracks. Particularly preferred is 1.0 to 1.2 times stretching Longitudinal membrane. By stretching at least 1.0 times, the formation of a membrane becomes remarkable improved permeability for water, urea and other substances ensured while by stretching a maximum of 1.2 times in the longitudinal direction, the formation of a very high quality membrane is ensured will.

The stretching of the membrane in the longitudinal direction and transverse direction is carried out before drying or during the The beginning of the drying stage is carried out while the membrane still has a moisture content of at least The stretchability of a membrane has 100% by weight, based on the weight of the cellulose regenerated cellulose goes down sharply with a decrease in its moisture content, and it is difficult to carry out the stretching required according to the invention when their moisture content is less than 100%. The membrane, when stretched, should preferably have a moisture content have from 100 to 300%. To achieve the goals of the invention It is also necessary to reach the membrane to keep tension during drying and in particular to maintain this tension until the moisture content is reduced to at least 10%

• If the tension is released sooner, it is impossible to get a satisfactory membrane with very good

Maintain permeability for water and other substances.

To dry the membrane under tension, the use of a device shown in FIG. The dryer 14 shown in FIG. 4, which is provided with a stretching device 15 (FIG. 3), is advantageous. F i g. 4 is a plan view illustrating the stretching device. The membrane 18 is held at both ends with a film clamp 19 at station A in the stretching device 15. The stretching device is provided with two drive wheels 20 and 21 and a slide bearing 24, which is movably arranged in guide rails 22 and 23 for rotation in the direction of the arrow to take along the film clamp 19. The membrane is moved forward through the film clamp 19 and stretched in the transverse direction in station B from a width W \ to a width W _2. Simultaneously with the stretching of the diaphragm in the transverse direction, the distance between the film clamp 19 from Fi to P _{2 is} increased, as a result of which the diaphragm 18 is stretched in the longitudinal direction. The distance between the film clips 19 is increased by changing the distance between the guide rails 22 and 23 from a \ to a ₂ , so that the holding rods 25 connected in a Z shape are angularly displaced about the slide bearing 24.

The membrane, which has been stretched as required before drying or during the start of drying, is kept in the dryer to dry until its moisture content is reduced to 10% or less. A membrane made from regenerated cellulose tends to shrink when dried. In order to obtain a regenerated Cuoxam cellulose membrane according to the invention, essentially any shrinkage of the membrane during the drying stage must be prevented. More precisely, it is necessary to keep the _{value IV 3 shown in FIG. 4} equal to the value B 2 and the value P ₃ equal to the value P _2. Hot air from a hot air generator (not shown) is introduced through inlet 26 (FIG. 3) and discharged through outlet 27. After drying, the membrane is guided between the gap of rollers 16 and wound onto a roll 17

A method of making a tubular membrane according to the invention is as follows with reference to Figure 5, which shows a simplified side view showing a method according to the invention for the production of a tubular membrane from regenerated Cuoxam cellulose illustrated

A solution of cuoxam cellulose is introduced through an annular slot nozzle 31 (FIG. 5) with an inlet 32 introduced and from bottom to top through an annular slot (not shown) or exit into a coagulation bath 33, which consists of a solution containing about 10% sodium hydroxide. the Coagulating solution usually contains 5 to 20% sodium hydroxide. It is supplied through inlet openings 34 and 35 introduced into the bath 33 and discharged through outlet openings 36 and 37. The interior and Outer surfaces of the Cuoxam cellulose solution extruded in the form of a tube are coagulated in the coagulation bath 33. At the same time, the hose becomes a tubular membrane 38 stretched. The tubular membrane 38 is pulled off upwards and in the Nip of rollers 39 placed above the coagulating bath 33, flattened The flattened one Membrane 38 is placed in two regeneration baths 40 and 41 containing about 5% sulfuric acid. The reference numeral 42 denotes a drive roller, with the c ine roller 43 via a chain, not shown Rotation associated with the roller 42. After leaving the regeneration baths, the membrane is in the wash baths 44 and 45 were introduced and carefully washed with water. If necessary, the membrane will in a bath 46 containing a plasticizer, e.g. B. glycerol or propylene glycol, is introduced. the Membrane is then passed through dewatering rolls 47 and fed into a dryer 48. A gas is blown into the membrane, causing it to be stretched into a tubular shape and both lengthways and is also stretched in the transverse direction, as shown in FIG. 6, which is a simplified side view of FIG shows the membrane expanded to the tubular shape in the dryer 48. The membrane is through the Pinch rollers 49 in the. Dryer introduced. Air, nitrogen, or some other gas for which the membrane is responsible is barely permeable, is blown into the membrane through its front end, causing it to form a tube is stretched.

The tubular membrane is stretched both in the longitudinal direction and in the transverse direction while it is continuously dried in the stretched state. It can be stretched in the longitudinal direction by changing the speeds at which the pinch rollers 49 and 50 are driven so that the rotational speed of the pinch rollers 50 is 0.9 to 1.3 times, preferably 1.0 to 1, 2 times the rotational speed of the pinch rollers 49 is. The stretching of the membrane in the transverse direction can be adjusted by regulating the amount of gas blown into the tubular membrane. The adjustment is made so that the degree of stretching, which is defined as T ₂ / 'Ti, where Tj is the width of the flattened membrane before it passed the nip of the nip rollers 49, or' / 2 of the circumference of the membrane in the Tubular shape and T _{2 is} the width of the flattened membrane after passing through the pinch rollers 50, 1.3 to 2.2 times, preferably 1.5 to 2, O times.

The tubular membrane remains in the stretched state during drying because the gas filling of the Membrane is always included in the part lying between the pinch rollers 49 and 50 and despite the Movement of the membrane through the pinch rollers 50 does not escape. Hot air from a not shown Hot air generator is introduced into the dryer through its inlet 51 and through its outlet 52 The tubular membrane is dried in the dryer until its moisture content is reached Has been lowered 10% or less, and then to one Roll 53 wound

The following are the methods for determining the physical properties of the membrane im Described within the scope of the invention.

1) wet elongation

The flat or tubular membrane of regenerated cuprammonium cellulose is kept for 24 hours in a room where the temperature was 20 ⁰ C and the relative humidity is 65% A rectangular test piece of a length of Imocm and a width of Jt _0. cm exactly along the Longitudinal and transverse edges of the membrane cut. The sample is immersed in water at 37 ° C, held in the water for one hour, removed from the water and transferred to a

Glass plate is placed, on which its length and width are measured immediately. If the length is designated by Im and the width by It , the wet elongation of the membrane can be determined as follows:

Wet elongation in the longitudinal direction // «= x 100

In the ₀

Wet elongation in the transverse direction,% =

It ₀

X 100

If the value obtained here is a positive number, it means that the membrane has passed through the Exposure to water has been stretched, while a negative value indicates shrinkage.

2) Degree of orientation

The degree of orientation π of the membrane is determined as follows: Several membranes are placed one on top of the other so that their longitudinal and transverse edges are exactly on top of each other and a rectangular piece with a thickness of 1 mm, a width of 10 mm and a length of 15 mm to accommodate the X-ray diffraction pattern is formed. The test specimen is placed in a "Geiger flex DS" X-ray tester (manufacturer Rigaku Denki Co.), and Cukot rays, which are generated at 30 kV and 20 mA and filtered through a Ni filter, are directed perpendicularly onto the test specimen. The hole collimator has an inside diameter of 2 mm and the measuring slit has a length of 1.0 mm and a width of 1.0 mm. The degree of orientation η is obtained from the following formula on the basis of the half-value width H of the starch distribution, determined along the Debye-Scherrer ring (002) (101) of the cellulose with a reflection of 20 Θ = 21 ":

π (X) =

180 - //
180

x 100

To determine the half-value width H , a baseline is drawn in contact with the minimum points on both sides of the maximum peak of an X-ray intensity curve that has been produced by plotting the intensity on the vertical axis and the angular displacement along the Debye-Scherrer ring on the horizontal axis, draw a line perpendicular to the base line through the top of the peak, a horizontal line through the center of the vertical line, and convert the distance between the intersection of the horizontal line and the curve on both sides of the peak into an angle.

J) water permeability and
Eligibility for dialysis

The water permeability of the membrane is defined as the ultrafiltration rate at a pressure of 400 mbar at 37 ⁰ C and in ml / m ² · h. Mbar expressed The Dialysierungsvermögen the membrane of the mass transfer for urea and BSD at 37 ° C is defined by a coefficient, and in cm / sec. χ 10 " ⁴ cm / sec. expressed

4) Wet burst strength

The wet burst strength of the membrane is expressed by the pressure (mbar) which causes the bursting when acting on one side of the membrane, which is stretched over a round frame with a diameter of 3 cm and is ^{wetted with water at 20 ° C.} The invention is further illustrated by the following examples.

Example 1 (flat membrane)

A flat membrane made from regenerated Cuoxam cellulose was made using the wet apparatus shown in FIG. A solution,

ίο the 9% cellulose, 3.6% copper and 7% ammonia contained, was through a T-shaped nozzle with an outlet width of 1 m into a Koagulierurigsbad, the Containing 10% sodium hydroxide at 30 ° C, extruded. The cuoxam cellulose solution was coagulated while it at a speed of 10 m / minute through the drive rollers 3 through the coagulation bath was pulled. The material coagulated here was introduced into the regeneration baths 5 and 6, the 5% sulfuric acid at 25 ° C to remove copper, ammonia and sodium hydroxide from the material remove. The material was then introduced into washing baths 10 and 11 and mixed with water washed. The drive rollers 8 and 9 in these baths were driven at a speed of 10.5 m / Min. In the regeneration bath 6 and 11 m / min, in the regeneration bath 7 and in the washing baths 10 and 11 driven. During the passage through the coagulation, regeneration and wash baths the cellulose membrane shrunk in the transverse direction to a width of about 65 cm after washing would have. After washing with water, the membrane was placed in a glycerin bath and washed with 15 Parts by weight of glycerol per 100 parts by weight of cellulose coated. The membrane was then passed through the dewatering rolls 13 and drained until it had a moisture content of 250%. The membrane was then at a speed of 11 m / min, a stretching device as shown in FIG. 4 is fed and fed both longitudinally and in Transverse direction stretched to a predetermined degree. It was then put in a dryer in which a controlled temperature of 110 ° C prevailed, dried. The properties of the membrane were different in Depending on the degree of stretching in the longitudinal direction and transverse direction. The properties are in Table 1 mentioned, in which the properties of a commercially available under the name »Cuprophan« available and commonly used for blood dialysis membrane made of regenerated cuoxam ceilulose are specified. It is found that a membrane with negative wet elongation in the transverse direction has a high Water permeability has very good dialysis capacity and a high resistance to bursting and has a represents superior selectively permeable membrane These features are particularly salient when the membrane had a wet elongation in the transverse direction of -2.0% or less, a negative wet elongation in Has a longitudinal direction and a degree of orientation of 70% or less, in particular 65% or less

Example 2 (hose membrane)

A tubular membrane made of regenerated cuoxam cellulose was produced using the method described in Fig.5 manufactured a device Cuoxam cellulose solution, which contained 9% cellulose, 3.6% copper and 7% ammonia, was through a Ring slot nozzle with a diameter of 5 cm in the form of a hose

that lO ° / oiges sodium hydroxide at 30 ⁰ C contained in a coagulation bath extruded. The tubular membrane was stretched and coagulated 1.6 times in the coagulation bath by appropriately adjusting the difference between the level of the coagulation solution inside and outside the membrane while it was moved at a speed of 5 m / minute by pinch rollers 39 arranged above the coagulation bath was pulled up from the bottom. The membrane coagulated in this way was introduced into regeneration baths 40 and 41 which contained 5% strength sulfuric acid at 25 ^° C., as a result of which the copper, ammonia and sodium hydroxide were removed from the membrane. The membrane was then washed in wash baths 44 and 45 with water. The drive rollers 42 and 43 in these baths were driven at speeds of 5.2 m / minute in the regeneration bath 40 and 5.5 m / min, in the regeneration bath 41 and in the washing baths 44 and 45. The tubular membrane shrunk as it passed through the

Table 1

Transverse coagulation, regeneration and washing steps by about 30%.

The membrane washed with water was placed in a glycerin bath and added with 30 parts by weight 5 glycerol per 100 parts by weight of cellulose coated. It was then dewatered by dewatering rollers 47, until their moisture content was lowered to 250%. The membrane was stretched in the manner shown in FIG. 6 shown dryer. The pinch rollers

ίο 49 in front of the dryer were at one speed driven by 5.5 m / minute, while the pinch rollers 50 behind the dryer according to the Longitudinal elongation of the membrane were controlled. The dryer had a total length of 8 m and was

15 kept inside at a temperature of 120 ° C.

The properties of the tubular membrane produced in this way are given in Table 2, in which also has the properties of a known one commercially available under the name »Cuprophan«

20 tubular membrane made of regenerated Cuoxam cellulose are specified.

attempt strain Thickness, Glycine tensile strenght Wet stretch Wet- Orient Water- Dialysis No. μηι rin- (dry. bursting lie- by- assets lengthways across lot. N / mm ² ) lengthways, crossways. solidifying foresight casual- (x 10 " Wt% %% speed. degree U) speed cm / sec.) lengthways across mbar % ml / m ² Hours. Urinary VB12 *) mbar material

1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
1-9
1-10

Commercially available
membrane

1.05

1.05

1.05

1.05

1.05

1.05

1.05

1.0

0.95

1.05

1.0
1.2
1.3
1.4
1.6
1.8
2.0
1.8
1.8
1.8

12th
12th
12th
12th
12th
12th
12th
12th
12th
6th
12th

15th

15 15 15 15 15 15 15 15 15 15

129.4

116.7

112.8

107.9

101

96.1

93.2

93.2

91.2

98.1

133.4

74.5

79.4

85.3

93.2

95.1

94.1

95.1

96.1

39.2-2.3
-2.3
-2.3
-2.2
-2.2
-2.1
-2.1
-0.5
+ 2.2
-2.5
-0.9

+ 5.4
+ 1.0
-0.3
-1.8
-3.8
-5.5
-7.1
-5.7
-5.9
-5.5
+ 4.1

299
319
339
386
505
545
559
539
472
286
293

82
75
70
68
62
57
0

59
67
58
85

3.3 3.7 4.1 5.7 7.1 7.8 8.3 8.6 5.7 15.7 3.0

9.5 9.7 10.1 10.4 10.9 11.3 11.5 11.1 10.3 17.1 9.8

0.80 0.84 0.96 1.13 1.37 1.48 1.53 1.45 1.10 2.50 0.75

*) VB12 = vitamin B,

Table 2

Try stretching thickness. Glyce tensile strength wet elongation wet orien water dialysis

along. across.

No. along across μτη πη- (dry, lot. N / mm ² ) Wt% 1.1 1.0 lengthways across 2-1 1.1 U 20th 30th 114.7 38.2 2-2 1.1 1.3 20th 30th 103 55.9 2-3 1.1 1.4 20th 30th 97 62.8 2-4 1.1 1.6 20th 30th 94.1 67.7 2-5 20th 30th 88.3 75.5

-3.5 +6.5

-3.4 +1.2

-3.4 0

-3.3 -1.3

-3.3 -3.2

bursting deep by capital VEl. solidifying foresight casual (x 10 " speed. Degree (--) speed cm / sec.) 0.62 mbar % ml / m ² ■ 0.65 Hours. urine 0.74 mbar material 0.87 426 80 2.4 8.2 1.04 466 74 2.8 8.4 505 69 3.2 8.7 579 67 4.1 9.0 725 60 5.1 9.4

13th 14th

continuation

attempt
No.

Elongation thickness,

; jim lengthways across

ülycerin-

amount,% by volume tensile strenght

(dry.

N / mm ³ )

lengthways across

Wet stretch

along,

Wet burst
across, solid% wedge,

mbar

Degree of orientation (, -)

Water-

by-

casual-

speed

ml / m ² -

Hours.

mbar

Dialysis capacity (X IO ' ^A cm / sec.)

urea

2-6 1.1 1.8 20th 30th 2-7 1.1 2.0 20th 30th 2-8 1.0 1.8 20th 30th 2-9 0.95 1.8 20th 30th 2-10 1.1 1.8 7th 30th Trade - - 20th 30th usual membrane *) VB12 = vitamin B ₁₂

85.3 82.4 -3.3 -4.9 785 53 5.6 9.7 1.12

83.4 85.3 -3.2 -6.1 805 0 5.9 9.9 1.15

84.3 84.3 -0.5 -5.1 771 55 5.5 9.6 1.10

82.4 85.3 +2.6 -5.4 645 64 4.1 8.9 0.90 88.3 86.3 -4.0 -4.8 293 54 15.4 16.5 2.45

104 37.3 -4.0 +3.2 439 82 2.3 8.2 0.60

For this purpose 4 sheets of drawings

Claims (1)

Patent claims: 1. Selectively permeable membrane made from regenerated Cuoxam cellulose, which is produced by a) a solution of Cuoxam Celiulose is extruded into a membrane, b) the extruded membrane coagulates, c) regenerates the coagulated membrane, d) washes the regenerated membrane, e) the coagulated, regenerated and washed membrane dries,