DD154068A5 - SEMIPERMEABLE CELLULOSE HOLLOW FIBER, METHOD FOR THE PRODUCTION AND DISCONNECTION OF SUCH FIBERS - Google Patents

Abstract

The invention relates to semipermeable cellulose hollow fibers for use in dialysis, osmosis or ultrafiltration separation cells, in particular for the detoxification of blood by hemodialysis, and a process for their preparation. The aim of the invention is to improve the properties of the fibers, in particular with regard to their wet tensile strength and their Wasserpermeabilitaet. The fibers according to the invention are characterized by an ultrafiltration coefficient K deep UFR of about 2 to about 200 ml / h / m high 2 / mm Hg; a urea coefficient K t ief urea of about 15x 10 high minus 3 about 45x 10 high min 3 cm / min and an intrinsic wet tensile strength of about 2 to 11 g / g cellulose polymer. They are made by: a) melt spinning from a melt spinning composition consisting essentially of about 35 to 80 weight percent cellulose ester and the balance polyol with a molecular weight of 106 to 900; b) hydrolyzing the cellulose ester hollow fiber; c) repapidating the cellulose fiber with a water-soluble plasticizer; and d) drying the plasticized fiber.

Description

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The invention is directed to semipermeable cellulose hollow fibers of the type "the dialysis' = _s osmosis or Ultrafiltratiöns ~ separation cells suitable sindy especially for cell ^ are verv for detoxification of blood by hemodialysis or hemofiltration / ends." The invention also relates to a process for the production of new fibers »

Most cellulosic fibers * used in artificial hemodialysis hemodialysis hitherto have been prepared by melt-spinning a cellulose ester such as cellulose triacetate j in a continuous process as disclosed, for example, in U.S. Patent 3,546,209. Hollow fibers were prepared using the copper-peanut method. An improved process is described in US Pat. No. 3,888,771. "While these basically different processes produce cellulose fiber having acceptable water permeability (ultrafiltration) and urea permeability (purification , clearance) for use in artificial ligation; their permeabilities, on the whole, are not optimal *. For example, cellulosic fibers prepared by the process of US Pat. No. 3,546,209. a lower water permeability than is desired with fibers having acceptable clearance properties for urea, creatinine, vitamin B ^ p, and other low molecular weight blood contaminants.

In addition, the continuous production of cellulose fibers excludes.Melt-spun cellulose

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acetate !! the chemical conversion of the thermoplastic cellulose acetate into the non-thermoplastic cellulose polymer by hydrolysis with saponification in an aqueous alkaline bath. During hydrolysis, the small diameter thin walled fibers are extremely sensitive to contact and break easily. Successful manufacture at a just sufficient grade to be commercialized depends on sufficient tear resistance being maintained in the pasquer maintained at the stage of manufacture where moisture prevails to avoid breakage or damage. "

The concept of producing semipermeable hollow fibers by melt spinning a plasticized polymer composition. was developed in the early 1960's and first disclosed in U.S. Patent 3,423,491. The patent discusses various types of polymers, including cellulose esters, and discusses suitable plasticizers for use in the formation of melt spinning compositions containing various thermoplastics. The polymeric cellulose esters have been developed into inexpensive commercial polymers, particularly cellulose acetate, and sesame methylene sulfone, most commonly referred to as sulfolane , was normally used as a plasticizer for the melt spinning composition for the production of cellulose acetate fibers. U.S. Patent Nos. 3,494,780 and 3,532,527 disclose improvements in sulfolane cellulose acetate acetate melt spinning processes wherein cellulose acetate fibers are extruded; they include either dipping the spun fiber after spinning into a bath containing a mixture of sulfolane and a polyol of molecular weight below 4000, or

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Modification of the Sulfolane Plasticizer Prior to Spinning the Paser by Including a Small Amount of a Polyol of Molecular Weight Below about 2,000 "These patents" also teach that polyols, alone as plasticizers, are useful in formulating melt-spinning compositions with cellulose esters, particularly cellulose acetates to be considered unsatisfactory *

It is the object of the invention to improve the properties of the fibers, in particular with regard to the tear strength of the fiber, in particular the wet tensile strength during the hydrolysis or the conversion of cellulose ester into cellulose before drying, storage and incorporation in hemodialyzers or hemofilters and with respect to their water permeability. »'.

The e _r invention has for its object to improve the wet tensile strength by a suitable Celluloseester-Sehmelzspinnzusammensetzung "

The sempermeable cellulose hollow fiber according to the invention is characterized in that it has an ultrafiltra

Efficient enττρρ from about 2 to about 200 ml / h / m / ram

HG; a urea coefficient K "of from about 15" 10 "" to about 45 x 10 cm / min and an intrinsic hack crack resistance of from about 2 to about 11 g / g of cellulose polymer has c '.

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It is obtained by:

Melt spinning a cellulose ester hollow fiber from a melt spinning composition which comprises from about 35 to about 80% by weight of cellulose ester and the remainder to 100% by weight of at least one polyol of average molecular weight in the range of about 106 to about 900 exists;

extensive hydrolysis of the cellulose ester hollow fiber to a cellulose hollow fiber;

Y / Merplastifying the cellulose fiber while still wet with a water-soluble, largely non-volatile plasticizer and

Drying of the plasticized paser »

The semipermeable cellulose hollow fiber made according to the present invention has an outside diameter of about 200 to about 400 / μm and a wall thickness of about 12 to about 80 / unit and has an intrinsic wet tensile strength in the range of about 2'to about 11 g / g polymeric cellulose

For the preparation of the semipermeable hollow fiber according to the invention, a / melt spinning composition is used which contains about 40 to about 50 % cellulose ester.

According to the invention, a cellulose ester is used which consists essentially of cellulose diacetate. "A cellulose ester which includes cellulose acetate propionate is also used.

As Polyoi at least one of the group of Polyethylenglykolenj. Polypropylene glycols and glycerin

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used "

For example, the semi-permeable cellulose hollow fiber of the present invention is made from a melt spinning composition whose polyol is a mixture of polyethylene glycols of average molecular weight below and polyethylene glycols of average molecular weight greater than 900, the polyol composition having an average molecular weight below about 900,

The invention is based on the surprising discovery that cellulose ester Schimmelzspinnzusaiameixsetzungen which are sulfolane-free and include only certain low molecular weight polyols or mixtures thereof, can be melt-spun into fibers which can be hydrolyzed to cellulose fibers, the wet strengths during the conversion of the ester · into which 'cellulose is much better'. The omission of sulfolane, which has heretofore been considered necessary, is the key change that enables the production of the substantially improved fibers of the invention. The resulting cellulose ester fibers of the invention have satisfactorily high intrinsic wet strengths in their spun form and above ', the parsers are spun retain their intrinsic resistance to tearing during Polyollaugung and hydrolysis or deacetylation, so the steps that Celiulose'este'rfaser in'welchen in the cellulose fiber converted wird5 in "in some cases, even the intrinsic R _e increases ißfestigkeit "

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The improved semipermeable)! Cellulose hollow fibers according to the invention are obtained by melt-spinning a cellulose ester melt film composition. made _? containing about 35 to 80% by weight of a selected 'cellulose ester or cellulose ester mixture and one or a mixture of polyols having an average molecular weight in the range of about 106 to 900'

Cellulosic esters that are suitable include cellulose mono-, di- and triacetates and mixtures thereof, cellulose acetate propionate, cellulose acetate butyrate, cellulose propionate and cellulose butyrate, and mixtures of two or more of these esters. The acetates are preferred, especially cellulose diacetate 5 and mixtures preferably include at least a small proportion of one or more other cellulose acetates.

The class of polyols is not quite suitable for the preparation of an acceptable melt-spinning composition, but the lower molecular weight polyols, for example, an average molecular weight in the range of about 106 to 900, attempts to use a single polyol of molecular weight of about 600 with cellulose acetate. failed because the composition could not be spun. However, satisfactory melt-spinning compositions have been obtained using polyol blends in which one of the polyols has an average molecular weight substantially greater than 900, for example 1400; a mixture of two polyethylene glycols, one of which had a molecular weight of 200 and the other had a molecular weight of 14-50, so that the average molecular weight of 902 was found to be suitable in the preparation of a cellulose acetate "schinol" spinning composition spun into hollow fibers. , Which had the improved tear strengths,

which characterize the fibers of the invention: mixtures of polyethylene glycols with polyols, for example, a mixture of polypropylene glycol of 400 average molecular weight and glycerol gave a spinnable composition, while polypropylene glycol of average molecular weight 400 alone gave no spinnable composition. Mixtures of polyethylene glycols and ethylene glycols have been satisfactory, and mixtures of two or more low molecular weight polyethylene glycols can be used with or without glycerin.

It has also been found that pure polyethylene glycols or polypropylene glycols which are too high in molecular weight to form a spinnable cellulose ester composition can be modified by the addition of glycerine, a known non-solvent for cellulose esters to obtain a composition. The amount of glycerol needed for this purpose varies with the molecular weight of the pure polyethylene or polypropylene glycol and also with the cellulose ester or ester mixture present. In general, the amount of glycerol that is required is higher as the average molecular weight of the race Glycol increases above about 600. The glycerol concentration should also be increased if the proportion of cellulose ester , doT, with the cellulose

diacetate is mixed, or added to Schuielzspinnztis amine compositions prepared from cellulose propionate or cellulose butyrate or mixtures thereof. As a general rule that glycerol in the range of about. 5 to 35 wt .- ^ ₅ based on the cellulose Schnielzspinnzusammensetzung, can be used successfully. Polyols having at least two hydroxyl groups in the molecule which are suitable include: diethylene glycol, triethylene glycol, tetraethylene glycol, the mono '' di- and tripropylexigl3 'koles, and mixtures of one or more of the propylene and ethylene glycols or glycols with ethylene -propylene glycol boots in the molecule, and mixtures of any one or more of polyethylene or polypropylene glycols with glycerol in an amount less than 50 vol .- ^ the glycol Glycerinmi s chung _e

The process of the invention comprises the steps of mixing the selected cellulose ester and polyol to form a Schimmelzspiimzusamensetzung, melt spinning the hollow fibers and cooling them to a gelartigen self-supporting state, hydrolysing or Entacetylieren the Celiuloseester hollow fibers to substantially cellulose fibers, deh, hydrolyzing a essential part of the ester groups with formation of hydroxyl groups. Complete hydrolysis is usually not achieved, nor is it necessary, but in order to obtain the best permeability and to store it during storage and shipment.

The polyol present in the as-spun cellulase ester fibers is normally leached out of the fibers during the hydrolysis or deacetylation. Alternatively, the polyol could be in a separate state Stage can be removed after the hydrolysis.

For example, semipermeable cellulose hollow fibers made industrially from a sulfolane acetate melt spinning composition by the process of US Pat. No. 3,520,609 and widely used in artificial kidneys after about 1972 had a water permeability coefficient K of about 1, 0 to 1.2 ml / h / m fiber surface area / mm Hg over the semipermeable fiber wall at 37 ° C ₅ a urea coefficient K__ of about 28 to 30 χ 10 cm / min, and a fiber tenacity after decalcification of about 1, ^ to about 1.8 g of intrinsic fiber tear strength / g of polymeric cellulose. "The improved cellulose fibers of the invention are substantially better in all important functional properties. The most surprising and most clearly improved feature, is the increased intrinsic wet tear strength. As stated above, the wet tensile strength of the fibers is extremely important for successful continuous production in the production line. '·

For example, in a street, a cable of 16 to 30 fibers or a plurality of such thread cables running from the

Spinneret are passed through air to become a self-supporting hollow fiber, then rinsed through a series of liquids in handling tanks, which sequentially leach the polyol from the cellulose ester: oil, hydrolyze the ester to cellulose, rinse the hydrolysis product and excess hydrolyzate from the cellulose fiber During the wet-treatment stages, the fibers are subjected to stretching or a longitudinal force is applied while undergoing more extensive internal molecular rearrangements, especially those from the polyoleidene removal and the chemical changes during deacetylation of cellulose ester to cellulose result in fiber breakage or damage due to the inability of the polymer skeleton of each fiber to tensile or frictional forces during such continuous processing resists continuous work and is in the highest. Dimensions undesirable.

It has been found that cellulose acetate fibers, which are of a Schraspitzzusacimensetzung according to the invention, which is free of sulfolanes, tend to a greater proportion of their tensile strength, they have after cinching (as-spun tensile strength), during the Liege through. to maintain the consecutive wet-treatment stages

as the chamfers. made from sulfolane-containing melt-spinning compositions and long in the trade. Learn about ^1, certain of the improved fibers an unexpected increase in the tensile strength compared to the state after spinning * and this increase will take place during the hydrolysis step of the process. The cellulosic fibers of the invention have average intrinsic tear strengths, in the wet state after hydrolysis, which are at least two to seven times higher than those of the hollow cellulosic fibers prepared by the method of US Pat. No. 3,520,609 In this specification and claims, the term "intrinsic tear resistance" as applied to wet cellulosic fiber tensile strength measurements / breaking strength in g / g polymer of a 5 "by 8 cm length of a single wet fiber means the force required to break the fiber when device hangs vertically between two clamping jaws in an Instron _'e the tests to preserve the intrinsic wet tensile strengths, which are reported in Table I, the g of the polymer of a selected 5s08 cm fiber length represents an average weight in g which for each particular 5J by 8 cm sample of the cellulosic fiber by drying the adjacent 25 ^ 0 cm fibers d of equal weight to a constant weight of 25 * 1-0 cm in length and dividing the total weight by 500 ', to thereby obtain an average weight;

this was then used for the particular piece of fabric subjected to the Breaking Resistance Test. "Such an approach increases the accuracy of the tear strength determination by eliminating the potential error due to fiber wall thickness change along the continuous fiber. In addition, each tear strength value averages six determinations various 5jO8 represents cm long samples "the thus determined increases in intrinsic tear strength _s are sindj been achieved economically Ύοη importance because a continuous production of the fibers, is considerably improved by the invention in terms of the production capacity through them,

While the above-described effects of increased wet tensile strength during the fiber production from high .wirtschaftlichen ¥ are ert, the increase in water permeability which is achieved in particular fibers which are made by the inventive method is to have ₃ also extremely important "Certain fibers up to SO times higher Tvasser permeability compared to the cellulose fibers available hitherto obtained from cellulose acetate-adhesive spinning compositions. Such an increase in Yasser permeability means that the ability of the fiber to separate water from a water-containing liquid, such as blood, is drastically increased, and the practical advantage that results therefrom is significant in that it provides a high yield

- τβ- -

substantial reduction of the time required per Hämodialysebeiiandlung is possible, which is understandable to the expert.

The formulation of the melt-spinning composition can be done in any suitable manner using a conventional method. Mixing device, which is essential to ensure sufficient mixing and to obtain an intimate uniform mixture. For example, dry cellulose acetate powder is selected with a weighed amount. Polyols blended in eir.iem yielding Hobart mixer. The blended material is then further homogenized and blended by charging it into a heated counter-rotating twin screw extruder and then forcing the molten extrudate through a mire hole spinneret _t, for example, a 16 to 30 hole die. The spinneret may be one that has conventional gas feeds to push gas into the core of the extrudate. A preferred gas for this purpose is nitrogen, but other gases can be used with satisfactory results, such as carbon dioxide, air and other harmless gases. If desired, a spinneret may be used which has means for injecting a liquid into the extrudate core, which liquid may not be a solvent for the cellulose ester and the polyol. Such a spinnerette is disclosed, for example, in U.S. Patent No. 3,888,771. The

Foctrudate exiting the spinneret is subjected to cooling, for example by means of compressed air under pressure and / or temperature, to effect gelation and solidification of the extrudate to form a solid self-supporting paser.

The cellulose ester fiber can be satisfactorily hydrolyzed by any of the known acetylation methods. The preferred method is to use an aqueous Natriumhydroxidbades "Suitable techniques are described in a variety of books and one · relevant magazines, including sum as Laidler, Chemical Kinetics, · McGraw Hill Book _Co.'s New York (195o), p 282 -290; Howlett, et al., Technical Inst. J, 38, 212 (1947) 5 Hiller, Jour. Polymer Science 10, 385 (1953), etc. After rinsing to remove the hydrolysis .products and excess Hydrolisierungsmittels or to neutralize them the still wet fiber is plasticized with a water soluble, non-volatile plasticizer substantially according to US-PS 3 209 $ h6 , By the term "substantially non-volatile" is meant in this specification and claims that the plasticizer is substantially retained by the cellulose fiber during the subsequent drying stage and storage at normal temperature. ..

Suitable plasticizers for deacetylated cellulose fibers

include those capable of swelling the fiber, presumably through interactions such as hydrogen bonding or dipole-dipole reactions. Preferably, water-soluble, substantially nonvolatile plasticizer is a hydroxyl group-containing compound, and especially a polyol such as polyalkylene oxides; Glycols such as ethylene glycol, diethylene glycol, bipropylene glycol, tripropylene glycol and the like; Glycerin and the like. Glycerol is a preferred plasticizer.

After plasticizing the fiber, it may be dried by any of the known methods, for example by vacuum drying, compressed air drying at normal or elevated temperature, temperature, microcrystalline drying and the like. Elevated temperatures may be used as long as there is no substantial plasticizer loss. Consequently, increased drying temperature depends on the particular plasticizer used; the appropriate temperature can be easily determined

The dried finished cellulose fibers of the invention have capillary diameters. The outside diameter is in the range of about 200 to hOO do, the wall thickness in the range of about 10 to 80 pm. For separation cells used in hemodialysis, the fibers preferably have a wall thickness in the range of about 10 to 50 μm and a maximum outer diameter in the range of about 230 to 320 μm. , · -

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The following examples illustrate the novel method and the improved cellulose hollow fibers of this invention and include the best mode _s to be applied, a * In this specification and the claims, unless otherwise specified,% percent by weight Each of the specially formulated Schmelzspinnzusainmensetzungen was charged with The fibers were prepared from a 16-hole spinneret while blowing nitrogen into the core. After gelling in air, samples were taken to determine the intrinsic pseudo-tensile strength after spinning. The fibers were deacetylated in alkaline solution, for example in 0.2 to 1.2% sodium hydroxide solution at a temperature in the range from 20 to

60 ⁰ Co

The intrinsic ultimate tensile strength after spinning was determined by weighing 1524 cm of the adjacent fibers to determine the average weight of the selected 5.08 cm section of each single fiber subjected to the test *

The resulting parsers are were then thoroughly washed in water and samples for the determination of wet tensile strength after, taken with the procedure earlier described, the product fibers were also tested for water permeability Ky-PSS and urea purity or Transport *% PBA ^ tested ^{11 e} ^ ^nem laboratory test apparatus ". The test apparatus consisted of a liquid

2s .-

reservoir, 'equipped with. a magnetic stirrer, and a dialysis spike cup provided with a magnetic stirrer, a cover closure plate with pressure fittings, and fittings for receiving the ends of the potting sleeves attached to each end of a fiber bundle of 128 to 178 fibers. The fiber bundle was bent in a U-shape, inserted into the cup and connected to the closure plate; a sleeve was connected via a fluid line to a pump which was connected via a line to the reservoir. The other sleeve was connected to the reservoir with a return line to pump fluid from the reservoir under controllable pressure through the lumens of the fibers in the dialysis cup. The beaker was also fitted with dialyzate inlet and outlet connections, and during the test, the fibers were immersed in a surrounding moving water pool for the K _{fJT? R} test.

The water transport coefficient Kv _n ^ was determined by pumping water under pressure through the fibers and measuring the increase in water volume outside the fibers in the dialysis cup. The tests were performed at 37 ° C. IC was then calculated for each test in ml / in ~ / h / mm Hg pressure differential $ as shown in Table I.

The urea coefficient K was provided by providing a

urea

Yester-urea in the feed reservoir and pump the solution through the fiber lumens; surrounding the fibers

226 Ό98, · · Pool in the dialysis cup was initially pure water. The urea concentration in the Dial} ^r SATF lüssigkeit was determined in-time intervals. The tests were carried out at 37 ° C and during the tests there was no pressure differential across the fiber wall surface. , ''

The urea coefficient K was calculated from the

urea

Difference between the urea concentration in the reservoir and in the Dialysierbecher at dei "outside of the fibers as a function of time and the fiber surface according to the following equation: N = IC _T p". A (C ₁ - C p) ₅ wherein N is the flux through the membrane in • Molen / min., C ₁ the initial concentration _s C "the final concentration or the measured concentration and A the area of the fiber wall or membrane between the two solvents»

In a two-chamber system without pressure differential or resulting ultrafiltration, the urea transition (transport) can be integrated through the membrane wall over a time interval t to obtain the following equation:

t = o

V v

^V I + 2

in which V ₁ meant the volume of the solution in the reservoir and volume of the solution in the dialysis cup

the

<a

In the tests, the volumes V and V "and the area A are measured separately, so that plotting the values of each side of the integrated equation gives a straight line _s

Slope allows K in cm / min to calculate.

a

An intimate mixture (blend) of cellulose diacetate poylmer and plasticizer was prepared as described above _s. The blend consisted of a mixture of 8Ό ^> cellulose diacetate and $ 20. a mixture of polyethylene glycols of molecular weights of 200 and 50 daltons to give an average molecular weight of the blended polyethylene glycol plasticizer of 902 Baitons. The cellulose diacetate hollow fibers were then deacetylated in a _0} 8 $ strength aqueous sodium hydroxide at 50 C to cellulose Hob-lfasern. The intrinsic tear strengths of cellulose hollow fiber membranes, water permeabilities (IC _n ^) and urea transport rates

(K) are listed in Table I, column 2. ^v urea '.

As can be seen from Table I, has the wet cellulose fiber of this example, about 2, 5 ^ma -l higher inti \ insic wet tensile strength than the · comparative fiber. The product cellulosic fiber made from this oil-soluble molecular weight polyolefin spinning composition also has better performance characteristics for blit cleaning and higher water permeability. The water permeability (Κ ™ -,) is 1. _f 5 times greater than that of the comparative fiber, D3.e Velocity

The transport of Harristoffs is also higher.

K = 38 χ 10 "^ cm / min, compared to 30x 10 ~ - cm / mxn.

OCE comparison Cellulosefaseriuembrän _e

On. similar mixture was excluded prepared by mixing cellulose diacetate and the same mixture of Polyethylenglylcolen an average molecular weight of 902, · that hy ^ o cellulose diacetate instead were used by 80 ^, after melt spinning the cellulose acetate ~ hollow fibers were in a 0 _$ ^^ cent, aqueous Sodium hydroxide solution hydrolyzed or saponified at 50.degree. When as described above testing, a _1} 3 times higher ixitrinsic wet tensile strength than that of the comparison fiber resulted. 'S. var Z6 compared to 30% of the same fiber, but K _T ~ _R was drastically increased to 86 times the Κ__ _Ώ - ¥ βΓΪβ3 of the comparative fiber, or a value of 104 ml / h / m ~ / mm Hg. From the comparison It can also be seen that a weaker hydrolyzing solution was used and that stronger saponification solutions were used to reduce water permeability at acceptable urea cleaning levels. In the case of a given plasticizer, the decrease in cellulase ester concentration causes a significant increase in water permeability at acceptable urea cleaning levels. Usually increase peymeability. Thus, the desired combination of intrinsic wet tensile strength, _$ IL and K, properties can be achieved by similar changes in melt spinning composition

It will be seen, however, that the molecular weight of the polyol is modified as shown in the example below. J2. '

An intimate blend of cellulose diacetate polymer and plasticizer was prepared as described above. The mixture consisted of hy $> a mixture of cellulose diacetate and 57% by weight polyethylene glycol having a molecular weight of 400 daltons, which after decacylation in an aqueous solution Caustic soda at 50 C obtained from the cellulose diacetate hollow fibers. Cellulosic hollow fiber membranes tested for intrinsic tear, water permeability and urea transport (K) The results are given in Table J, column G.

The intrinsic Kaßreißfestigkeit the product fiber is 2.4 times higher than the intrinsic wet tensile strength of Vergleichsfas ei "Ι ^ ττρρ 2, 1 time higher and K is 32 χ 10 ^J compared to 30 x ^10J of the reference fiber, it is hiiiEuweisen that during the saponification of cellulose acetate Ku cellulose the intrinsic wet tensile strength has risen to a value of nearly twice the intrinsic tensile strength after spinning _e

Bs became another mixture with the gleichoii. Proportions cellulose diacetate and Pοlyethy1englyko1 prepared au3geriomsen _f that the average molecular glycol

i * r <

hOO Dalton's weight was prepared by blending polyethylene glycol of average molecular weight 600 with glycerol of average molecular weight 92 daltons. This change brought about an improvement in all fiber properties; the intrinsic wet tensile strength of the cellulose fiber · ¹ 3,7tnal was greater than that of the reference fiber, IL was 3 _A hma.l greater than the .'gleiche coefficient of the reference fiber and K was ^{0 to} urea

- 3 - 3

33 x 10 ^J compared to 30 χ 10 ^J cm / min, the reference fiber,

Example 3

An intimate mixture of cellulose diacetate polymer and plasticizer was prepared as described above. The mixture contained hyalocellulose diacetate mixture and 57% polyethylene glycol of a molecular weight of 108 daltons. The cellulose diacetate hollow fibers were then heated in 10 _{sec of} seiger caustic soda deacetylated to cellulose holofilaser at 50 ° C. The intrinsic tensile strengths of the hollow fiber membrane, yener permeability and urea transport rate are listed in Table 3, column D,

As can be seen from Table 1, the wet cellulosic fiber of this example has a 1.9 times better intrinsic tenacity than the control fiber. The water permeability K ,, .. ™ is 1 _s 8 times higher than that of

UJbK

Comparative fiber and K is 32 χ ΊΟ ", cm / min, compared ^to urea '

at 30χ10 ™ · cm / min, the control cellulosic membrane.

A similar Geraisch was prepared in the same ¥ else except dr> -ß the polyethylene glycol has a molecular weight of 150 had The hydrolysis of the cellulose acetate to cellulose was made in a 0.4 $ igeii aqueous sodium hydroxide solution at 5O ⁰ C, The same Fiber properties determined as described above. The intrinsic wet tensile strength was 6.6 times the comparative fiber while

K ,, ™ -. and K are essentially equal to the vertices of the Ver-I FR.

same fiber were. A comparison of the intrinsic wet strength ^{1 of} the cellulosic fibers of Example 2 and Example 3 shows that the best wet strengths at a given cellulose ester concentration, hy $> cellulose diacetate, are obtained with an average molecular weight of the polyglycol between 106 and 40 Peak at a molecular weight of about 150.

Example h

jMA - A IJ * il- * Bl-I- in Bi> Il Il iji.l | i |

It became an intimate odor of cellulose diacetate polymer and Weicbjnacher. prepared as described above. The mixture consisted of HYF> a mixture of cellulose and 57 $ a mixture of Polyetliylenglykolen of molecular weights ί | 00 and 'i45O Dal tons. The average molecular weight of the polyethylene glycol soft

f% it.

Machers was 713 Daltons. The cellulose diacetate hollow fibers were then aserniembrane to cellulose Hohlf as described imagining deacetylated _b Fiber properties are listed in Table I, Column E.

It can be seen from Table I that the intrinsic wet tensile strength increased to over twice the intrinsic ultimate tensile strength after spinning and to an intrinsic cellulose wet tensile strength of 3 times that of the comparative fiber, at a K of 3hx. 10 opposite

X-iX O et

a value of 30 χ 10 cm / min of the reference fiber and a K _{1n 5} which was 2.4nal larger than that of the comparison fiber. ;

An intimate mixture of cellulose diacetate polymer and plasticizer was prepared as described above. The mixture contained 43% of a mixture of cellulose diacetate and 57% of a mixture of 400 Daltons molecular weight polyethylene glycol and 92% molecular weight glycerin daltons, so that the polyol mixture has an average molecular weight of 3 ^ 2 daltons, te "the cellulose diacetate hollow fibers were deacetylated in a 0.4 $ igeii aqueous sodium hydroxide 'at 5O ⁰ C Ku cellulose Hohlfaserraembrane. the intrinsic tear strengths ^ ppn" ¹ ^ ^K , values of the cellulose hollow-fiber membrane are listed in Table I, column F »

From Table I it can be seen that the intrinsic wet tensile strength increased by 2 ^ 2 ^ during saponification to give a cellulosic fiber whose intrinsic wet tensile strength was 5-fold that of Comparative <3r. was "The urea-cleaning 3 gr ad (urea clearance rate) was significantly increased to k Z χ 10 °" ^ cm / min, or 1.3 times the Vex'gleichsfaser while K ^ · _'s was 1 time higher second as the value of the comparative fiber e.

Another melt spinning composition, such as the above-described mixture of polyethylene glycol-glyceriix mixture and cellulose diacetate, was prepared except that the glycerin was used by an equal amount, J vol. - / o, of ethyleneglycol to give a polyol molecular weight of 358 average molecular weight to obtain. The same properties were "matched" to the resulting. Cellulose fiber in the same way. The cellulose fibers had a wet tensile strength of 5-8 times

- 3

the reference fiber was, a K value of 21 χ 10 ^to 'urea

cm / min, and an IC value which was 1.7 ^ aCbC of the value of the reference fiber.

A slime spinning, Taneri set was made by uniformly vortexing 36 $ of cellulose diacetate and 6k% of a po3-yol mixture consisting of a mixture of polyethylene glycol of average molecular weight 6θ Daltons

and glycerol, in such amounts that a weight average molecular weight of H'2 "\ resulted for the mixture" There were melt spun fibers and, in a O, Ji $ aqueous sodium hydroxide solution at. 50 C enta.cetyliert "The same characteristics as described, and summarized in Table -I, column G. These cellulose fibers have a combination of high wet tensile strength,

high K _TTrvn - and high K value and represent a preferred UBR urea ^D

Embodiment of the invention by such Fäsrn for. the use in hemodialysis or Häraofiltern, especially for use in llammof iltern are very suitable. The intrinsic wet tensile strength is the 3 x ^ dex comparative fiber, K is 3 to 2 times higher than the comparative fiber value

and K is k-9 χ 10 cm / min. urea

An intimate gum (blend) of cellulose diester (propionate / acetate) and plasticizer was prepared as described above. The cellulose ester of this example can generally be regarded as cellulose propionate, since 9 ^^ of the ester groups are propionate and only h ^> Aceta.t »

The mixture was 43 / »a mixture of cellulose propionate and 57 $. a mixture of polyethylene glycol, however, cut before the η molecular weight of 400 daltons and glycerol of molecular weight 52 daltons, so that the polyether mixture has an average molecular weight of

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362 Daltons had * The cellulose propionate hollow fibers were then 'deacetylated in a 0 _s 4% aqueous sodium hydroxide solution at 50 ⁰ C'. The intrinsic wet tensile strength of the hollow fiber, the water permeability and the urea, transfer speeds are summarized in Table I, column H.

As shown in Table I to. seen, the wet cellulose fiber of this Example was to the 3 _s 5 times higher intrinsic tear strength as the Yergleichsfaser. The water permeability, KtrcTOf is 2.4 times the reference fiber and the rate of urea transport * K _e * 33 x 10 "° ^ 'cm / min.

Thus, a seed spinning composition was prepared by intimately admixing 43 % cellulose diacetate and 57 % of a palaly mixture consisting of a mixture of polypropylene glycol of average molecular weight daltons and glycerine such that the average molecular weight of the polypropylene glycol / glycerine mixture was 297 % . , were made therefrom Cellulesefasern as described, wherein the deacetylation was carried out with a 0.4% sodium hydroxide solution at 50 ⁰ G * the determined. Properties are listed in Table I, column I. "'

Artificial kidneys of the type of under

Of 8 - 33 -

Artificial kidneys were made using cellulosic fibers obtained on an industrial scale by the method of Example -5. namely, using: a melt-spinning composition consisting of. hy $> cellulose diacetate and .5750 of a mixture of 4O0 daltons molecular weight polyethylene glycol and glycerin such that the polyol blend had an average molecular weight of 362 daltons. The wet tear strength became

h with 11 χ 10 ßyg cellulose fiber determined «

After the cellulose fibers had been rinsed with water and replicated with a solution of glycerol / water and dried, they contained about 20% glycerol. The intrinsic tear strength of these fibers was determined by a single fiber breakage test. on the Instron apparatus as described above in connection with the dry cellulose acetate fiber, with the following modifications: A fiber cable of 36O fibers and one meter in length was weighed, the glycerine extracted and the pure cellulose fiber weighed. The average molecular weight of a 5-8 cm long section was calculated on a 100 μm polymex fiber basis. The tear strength values represent the average of six separate tests on six 5 "-08 cm long Faseia from the glycerine-free fiber cable» The intrinsic dry tensile strength

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was 20 χ ίθ ⁴ g / g cellulose fiber.

One of the artificial kidneys containing 1.5 m of cellulosic fiber surface was dry sterilized using 2.5 MRAD gamma rays. After sterilization, the leaves were opened, paser samples were taken and subjected to intrinsic hack cracking. It was found that the fibers An average intrinsic tear strength of S ₉ 6 χ 10 g / g cellulase fibers was "Another 1.5 in artificial kidney was prepared, with the cellulose fibers filled with saline while the serum was filled with 2.5 IRAD gamma rays was sterilized. Fibers from this wet sterilized gamma-ray had a.e. intrinsic hackbreaking strength of 5.2 x 10 g / g cellulose fiber ^

In comparison, in artificial relationships, the ·

2 -

1.5m cellulose fibers which had been prepared according to the method of US-PS 35 4-6209,. tested the same way, found the following values:

Intrinsic Dry Tensile Strength of Cellulose Fiber -

7.5 x 10 ⁴ g / g

Intrinsic Bass Tensile Strength of Cellulose Fiber -

1.6 χ 10 ⁴ g / g

Intrinsic hack cracking strength of the cellulose fiber after sterilization with gamma rays in the dry state 1.53 x 10 ⁴ g / g ·

Intrinsic hack cracking strength of the cellulose fiber after sterilization, with gamma rays in a wet state (physiological saline) ~ 1,2δ χ 10 ⁴ g / gV

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Clinical evaluations of two 1.5m artificial kidneys containing the improved cellulosic fibers of this example were performed on two hemodialysis patients at an average blood flow rate of 200 ml / milh and a dialysate flow rate of 500 ml / min for times-3, 5 and 4 »1 hours * The K _upR value was _{2> 1} _al__ _{at 37} ο _Ce The K

hm .mm Hg, ^ ^rea

Value was 31.6 cm / min at 37 ⁰ C.

In comparison, commercially available artificial

Kidneys containing 1.5 m cellulose fibers prepared according to US Pat. No. 3,546,209, used in three hemodialysis patients, with average values for

hg

at 37 ° C and a K _ value of 29.6 cm / min

received at 37 C v / urde

The artificial hives used in this example are devices with a pair of blood cankers separated by a dialysate chamber interposed therebetween

i _Λ « ⁿ

A bundle of hollow fibers, usually consisting of many thousands of individual fibers, for example, _from 10,000 to 15,000 fibers, terminate at their opposite S-ends in one piece tube base made of plastic, for example;. polyurethane the tubesheet bond the fibers among ^each, other and SChE ffen also includes an annular portion which außerw * is half of the circumference of the fibers in the bundle of the part serves to the tubesheet with the. To connect the final examiners of the dialysate chamber and the Blu.tkamine.rn and thereby to enclose the blood chambers and the rialysatkammer in one unit, with the fibers in the Dxalysatkammer, so that the Eamniem stand isolated from each other in fluid-tight connection. the hollow fibers terminate in the plane of the outer end of each tube bottom and the passages in the HoJxI fibers create connections between the interior of the bXi £ distance g maintained blood chambers.

TABLE I (A) Comparative Example Commercially available cellulosic hollow fiber is disclosed in U.S. Patent 3,554,606,209 (B) Example No. 1 (C) Example No. »2 (D) Example # 3 #. (E) Example No.-V h He is chafing 7.2 χ 10 ' 7. ky-Sx O · · · 2.0x10 4,4x10 2,3x1O ⁴ (Α) Dry tensile strength of the cellulose etacrylate prior to the deacetylation of the titanium nitrate / g Cellulose ac et atpole lynier • of a single fiber of 5s> 08 cm in length 1,6 χ 10 4,2x10 ^: 3,9xio ⁴ - 3,1x10   i 5,1x10 (Β) Tear strength of the cellulose fiber after the entacety-ligation intrinsic tear strength / g of cellulose polymer of a single fiber in a 5 years. sample about -78 $ $ -43 + 195 ^ -20 ^ + 222 ^ (c) Change in fiber tensile strength during conversion from the spun cellulose acetate fiber to the final semi-permeable wet ellipsoidal fiber

va; 1.0-1.2 (B; (C) (D) f (E) Vergleicnsbeispiel example example example example   , In Handel 'receives Liche cellulose number 1 No. 2 No. 3 '· No. h Fasereigens claaf th Hollow fiber after US Pat. No. 3,556,609 (d) lj ^r aerer-permea.bili- 28-30 χ 10 "V the finished product wet cellulosic HoIaIf as ermemfor an 1.8 2.5 2.1 2.9 ICyP ₁₁ = cm ² / h / m ² / nnrJIg at 37 ° C (Ε) Harrstoff-Reini ge ο ge chwindig- iceit (clearance rate) of the finished 38X10 "^ 32x10 " ⁵ 32x10 "· - ' 34x1o "° moist cellulose - Hollow fiber membrane K - cm / min, at urea ' 37 ° C

TABLE I Fiber properties (F) Example No. 5 Example No. 6 (H) Bei''s-oiel no '. 7 Example No. 8 (Α) dry tensile strength of the cellulose ace'tatfaser before Sntacetylierung g intrinsic tear strength / g cellulose loseacetat-poiynier csn of a gene einzi- fiber in a length 5,0.8 3,8x1O ⁴ 3,7x1O ⁴ ' 5,7x1O ⁴ 5,9x1o ⁴ (B) Wet tensile strength of cellulose fibers after deacetylation: g intrinsic tear strength / g of cellulose polymer from a single fiber in a 5-cm 8 cm sample 9 _} 2x1O ⁴ 5.5x10. 5,6x10 3,6x1o ⁴ (c) Change in fat: tensile strength y ^ After conversion of the spun cellulose acetate fiber into the final semi-permeable wet cellulosic fiber + 242 $ · - . " (d) Water Permeability of the Finished Cellulosic Wet Cell Membrane Ky ₁ TO = cm ² / h / m ² / mmllg at 37 ° C 2.5. · 38.0 2.9 3.5 (E) urea purification rate (clearance rate) of the finished moist cellulose hollow-fiber membrane K = cm / min, at 37 ° urea ' 42x10 ~ ³ 49x1o " ³ 33x1o " ³ 44x1 o "" ³

Claims (2)

1 "· semipermeable cellulose hollow fiber, characterized in that it has an ultrafiltration coefficient of about 2 to about 200 ml / h / m / mm Hg; a urine substance coefficients K ^. from about 15x10 "- * to about 45x10" "cm / min" and has an intrinsic haptic strength of from about 2 to about 11 g / g of cellulosic polymer and is obtained by a) melt spinning a Celluloseester hollow fiber from a melt spinning composition consisting essentially of about 35 to about 80 wt .-% Celluloseester and the balance to 100 wt ··% of at least one polyol of an average molecular weight ranging from about 106 to about 900 'consists; b) substantially hydrolyzing the cellulose ester hollow fiber into a cellulose hollow fiber; c) replastifying the cellulose fiber while. it is still wet, with a water-soluble largely non-volatile plasticizer and d) drying the plasticized paser * Semipermeable cellulose hollow fiber according to item 1, - characterized in that it has an outer diameter of about 200 to etv / a 400 11m and a wall thickness of about 1'2 to etv / a 80 um * Semipermeable cellulose hollow fiber according to P _u nt 1 or _2? characterized in that it consists of a melt-spinning 29, 5. 1981 AP B 01 D / 226 098 58 534 12 Composition containing a mixture of poly (propylene glycol and glycerol) 4. Semipermeable cellulose hollow fiber according to one of the items 1 to 3s characterized in that it is made of a Sclimelzspinnzusammensetzung _s whose cellulose ester includes cellulose acetate propionate. Semipermeable cellulose hollow fiber according to item 1, characterized in that it is made of a melt-spinning composition whose polyol is a mixture of polyethylene glycols of an average molecular weight of less than 600 and polyethylene glycols of an average molecular weight of more than 900, wherein the polyol mixture has an average molecular weight below about 900. A method of making a semi-permeable cellulose hollow fiber of intrinsic ice tenacity ranging from about 2 to about 11 g / g of polymeric cellulose characterized by % a) melt spinning a cellulose ester hollow fiber from a melt spinning composition consisting essentially of from about 35% to about 80% by weight of cellulose ester and the remainder to 100% by weight of at least one polyol of average molecular weight   between about 106 to about 900; b) largely hydrolyzing the cellulose fiber into a cellulose hollow fiber; c) replastifying the cellulose fiber while it is still wet with a water-soluble, substantially - Jl - 29. 5 · 1981 AP B 01 D / 226 098 58 534 12 non-volatile plasticizer; and d) drying the plasticized paser. 7 «The method according to item 6, characterized in that a melt spinning composition is used which contains • about 40 to about 50 % of cellulose esters. 8 «Process according to claim 6 or 7 * characterized in that a cellulose ester is used which consists essentially of cellulose diacetate" Method according to one of the items 6 or 7, characterized in that a cellulose ester is used which includes cellulose acetate propionate. 10 »method according to one of the points 6 to 9, characterized in that at least one of the group of polyethylene glycols, Polypropylenglykblen and. ;. Glycerol is used. '