CN113089112A

CN113089112A - Spinning machine for producing cellulose fibres and method for operating the same

Info

Publication number: CN113089112A
Application number: CN201911336732.7A
Authority: CN
Inventors: H.施贝斯伯格
Original assignee: Lianjinge
Current assignee: Lianjinge; Lenzing AG
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2021-07-09

Abstract

The invention relates to a spinning machine for producing cellulose fibers and to a method for operating the same. In particular, the present invention relates to a process for the manufacture of modal fibres, wherein in the spinning step, new spinning baths are uniformly distributed along the spinning position and across the plates of each cluster spinneret. The invention also relates to a spinning machine which can carry out the method.

Description

Spinning machine for producing cellulose fibres and method for operating the same

Technical Field

The present invention relates to a modal process.

The modal fibers are characterized by the minimum requirements for tenacity and wet modulus according to the definition of BISFA. In addition, the technology used to make modal fibers with their unique combination of physical and textile properties, softness and fabric stability should meet the IPPC guidelines of the european ecolabel and Best Available Technology (BAT) for emissions from processes produced by proprietary manufacturing methods.

Background

Compared to the conventional viscose process, the key element of the process is a balanced combination of the following factors: low hemicellulose concentration in the impregnation lye, short ageing time and higher DP of the cellulose, higher input of carbon disulphide (CS 2) and sodium hydroxide (NaOH), use of special modifiers, viscose fibres with low cellulose concentration, high alkali ratio and high viscosity, lower concentrations of sulphuric acid and sodium sulphate and high zinc concentration in the spinning bath, higher number of spinneret holes, high drawing and low spinning speed and high specific formation and yield of sodium sulphate. In particular, the method may consist of the following method steps:

slurry material

All dissolving grade slurries of sufficient purity, reactivity, whiteness and appropriate viscosity are useful in the modal process. Such pulp can be prepared from softwood or hardwood or even non-wood materials by sulfite or sulfate techniques and used in the form of sheets, rolls or flakes. The integrated preparation of pulp and fibers allows the use of wet pulp, which can be fed directly into the pulper without the need for drying. The subsequent process steps in viscose manufacture need to be adjusted due to the physical and chemical performance of the pulp. The slurry may also contain an impregnation aid, which is a surfactant for better penetration of the impregnation lye.

Pulping

Wood-based cellulose, such as baled dry or wet pulp (48-50% dry matter), is mixed with a temperature-controlled sodium hydroxide liquor (impregnation liquor) containing 220-240g/l total alkali in a number of pulpers equipped with special turbine stirrers. Alkali Cellulose (AC) is formed from the reaction of cellulose with sodium hydroxide. Impurities like so-called "hemicellulose" and its degradation products are dissolved in the liquid.

The slurry is stored in a slurry tank from which it is continuously pumped to an AC press which separates the alkali cellulose from the pressed alkali liquor.

Alkali Cellulose (AC)

After pressing the pulp in a drum or belt press, a wet cake of alkali cellulose containing 32-34% cellulose and 15-17% caustic soda is obtained. The AC is crushed to obtain a high specific surface area prior to the aging process.

AC aging (Pre-aging)

The aging process is necessary to adjust the degree of polymerization of cellulose by depolymerization in the presence of air or oxygen in order to obtain the desired viscosity of the spinning solution. The shredded alkali cellulose is aged in a belt aging, aging drum, tower or cabinet apparatus. The aging time can be adjusted by varying the speed and temperature of the conveyor or drum, depending on different requirements. If desired, the pre-maturation process may be accelerated by adding a catalyst, such as cobalt chloride or manganese sulphate, to obtain an AC (SCAN) having an intrinsic viscosity of 400-450 ml/g.

After aging, the alkali cellulose is cooled in an alkali cellulose cooler, which operates as a fluidized bed reactor. A rotary cooling drum or a continuous flow conveyor may also be used.

Xanthation

The alkali cellulose is reacted with CS2 to give sodium xanthate, which is soluble in dilute sodium hydroxide (dissolving lye). For this purpose, AC was fed into the xanthator through a conveyor belt and a weigh bin. The exothermic reaction of AC with carbon disulphide is controlled by cooling the AC.

The reactor used may be a wet churn equipped with an intensive kneader, a continuous twin-screw kneader or a belt xanthator. Under vacuum, AC was reacted with CS2 liquid and kneaded like a dough until the reaction was complete. The CS2 input may be 35-38% based on cellulose.

CS2 also reacts with NaOH as a by-product of xanthate formation to form Na2CS3 and Na 2S.

A sufficient degree of substitution is required to dissolve the xanthate in dilute NaOH, expressed as ɣ value (CS 2 moles per 100 moles of glucose units). The concentration of sodium hydroxide determines the alkali content of the viscose. By varying the degree of substitution, the alkali-/cellulose ratio and the average length of the chains, viscose fibers of different quality can be achieved.

The xanthation apparatus may be of the Simplex or Suma type. The temperature at the beginning of the xanthation may be between 15 and 17 ℃ and the temperature at the end of the xanthation between 30 and 35 ℃.

Dissolution

The mixture of lye and xanthate is discharged into the dissolver through the homogenizer by feeding the cooled dissolved lye into the xanthator.

Homogenization of viscose fibres is achieved in a fine homogenizer at low temperature. The modifier is added to the viscose dope. The function of the modifier is to control coagulation and regeneration during filament formation in the spinning process. Many different compounds or their blends can be used as modifiers: amines and polyamines, quaternary ammonium compounds, amides, heterocyclic nitrogen compounds, polyglycols, ethoxylated ammonia derivatives, ethoxylated fatty acid amines and amides, ethoxylated glycerol and ethoxylated fatty acids, esters or alcohols. Many examples of these compounds, which may be used alone or as blends, are described in the k. foster ribbon tze, "Chemiefasern nach dem viskosher fahren", third edition, Springer, 1967, pp 635-641, the disclosure of which is incorporated herein by reference.

The amount of modifier is 1.0-4.0% based on cellulose.

The modifier can be added during the dissolution process, preferably directly into the dissolver, after degassing before the final filtration of the viscose fibers or directly before spinning.

This can be done by means of generally known devices for introducing substances into a stream of liquid medium. Preferably, there is a means, such as a static or dynamic mixer, after the addition location to provide uniform distribution of the modifier within the viscose fibers. Such mixers are well known and commercially available, for example Sulzer mixers. In a continuous process, the viscose fibres from the dissolver are further treated in two refiners to improve the dissolution state.

The unfiltered viscose fibres may have a cellulose content of 6.0-7.0%, an alkali content of 6.0-7.0% and a sulphur content of 1.7-2.0%.

Aging, filtering and degassing

After homogenization of the xanthate, the viscose fiber must go through successive maturation, degassing and filtration processes.

The ripening is carried out in tanks in order to obtain a better distribution of the xanthate groups on the cellulose chains and to obtain the desired ripening index or gamma value for the subsequent spinning process.

Prior to spinning, viscose fibres must be filtered to remove fibres, gel particles or other impurities, as this can block the fine spinneret holes and cause spinning defects. Instead of a conventional filter press, a continuous waste filter can be used, which is equipped with fine metal fiber fluff of different pore sizes. The filtration process is carried out in two or three steps in order to obtain the best filtrate quality.

Continuous rapid degassing to remove air bubbles was performed before pumping the viscose fibers to the spinning tank.

The spun viscose fibres may have a ball drop viscosity of 80-140s, a gamma value of 57-64, a cellulose content of 6.0-7.0%, an alkali content of 6.0-7.0%, a sulphur content of 1.6-1.9% and an alkali/cellulose ratio of 0.95-1.1.

Spinning

The modal staple fibers were produced on a spinning machine consisting of a spinning tank containing a spinning bath, a rotating godet with a variable drive and a ceramic guide for taking up the filaments and a final draw roll for collecting the individual tows after drawing in a hot secondary bath. Such draw rolls may be, for example, a triad of two sets of pressure rolls that squeeze the tow and reduce chemical entrainment into the acid wash, or a series of six or more non-squeeze rolls.

Viscose fibers were pumped by a gear pump, passed through a candle filter, and extruded through the fine holes of a spinneret immersed in a spinning tank.

Different spinning geometries can be applied for modal fibers: diagonal or vertical spinning, where there are two or three tows per godet.

For the purpose of ventilation, the machine is completely enclosed to recover the sulphide gases and to achieve safe working conditions in the spinning zone.

Fresh spin bath enters the spin tank from the bottom and overflows back to the spin bath system where it is degassed, filtered, excess water is evaporated, excess sulphate is crystallised and make-up chemicals are added to adjust the composition before it is recycled back to the spinning machine.

Coagulation and regeneration occur in parallel after the viscose fibres have been extruded through the spinneret holes. The viscose fibres coagulate and the high viscosity gel becomes a sol. During regeneration, xanthate is decomposed by the acid of the spinning bath into regenerated cellulose, and the caustic soda of the viscose is neutralized by the acid to form sodium sulfate. Both processes are affected by the following factors: the composition and temperature of the viscose and spinning bath, the type and concentration of the modifiers (which delay the regeneration process and their interaction with the components of the spinning bath), the spinning speed, the spinning geometry and the immersion length of the filaments, the spinning bath/viscose flow rate and the diameter and design of the spinneret holes, and therefore a careful balance is required to obtain fibers with the required physical parameters without spinning defects.

The tow from two or three spinnerets was collected, guided by a ceramic guide and wound three times around a godet roll. The tow is drawn by a take-up roll at the end of the spinning machine, the tow is introduced into a hot secondary bath (drawing bath) where the regeneration is completed and high drawing is applied so that the filaments gain strength by fixing the oriented cellulose molecules.

Due to the delayed regeneration, the spinning speed in the modal fiber process is much lower than in the conventional viscose process and can be 25 to 40m/min and higher elongations to 125% can be applied.

Spinning nozzle

Spinneret design and spinning geometry are key factors in achieving high quality modal fibers at high line efficiencies. Modal fibers need to be spun at much lower spinning speeds than viscose fibers, which can be compensated for by spinnerets with significantly higher hole counts. Such cluster spinnerets consist of cups arranged on a plate, which may be a full disc or an annular plate. The cup may be 12 to 16mm in diameter, with the hole diameter depending on the fibre titer (titer). The total number of holes per spinneret can be as high as 100,000 or even higher. In order to achieve a sufficient immersion length, the filaments are spun vertically or diagonally at an angle. The immersion length may be 40 to 80 cm.

Spinning bath

The spinning bath is an aqueous solution of sulfuric acid, zinc sulfate and sodium sulfate, which is circulated through the spinning machine. The viscose fibres are coagulated by the salts present in the bath and decomposed by the acid, giving regenerated cellulose filaments, Na2SO4, CS2 and H2S. In the spin bath circulation system, excess Na2SO4 is removed by crystallization, the sulfide gas is collected and recovered as CS2, sulfur or converted to sulfuric acid, and make-up chemicals sulfuric acid and zinc sulfate are added to adjust the spin bath composition.

In the spinning bath, the H2SO4 concentration may be 70-90g/l, the Na2SO4 concentration 90-130g/l, the ZnSO4 concentration 48-62g/l, and the temperature 37-43 ℃. The spinning speed, spinneret size, modifier type and spin bath composition (including temperature and dip length) are not independent of each other, but need to be well balanced to achieve the desired fiber properties.

Stretching bath

The drawing bath is an encapsulated hot acid bath comprising the spinning bath components in diluted form at a temperature of 90 to 98 ℃. Its function is to apply maximum tow draw between the godet and draw units while the regeneration process is still in progress to wash the tow to reduce spinning bath chemical carryover into post-processing and to collect sulfide gas from the system for recovery.

Cutting of

The tow from all godets was collected on a drawing unit to obtain a thick wire which was sucked into the wire injector of a cutter with acidic water and cut to the desired staple length with a rotating self-sharpening cutter.

The cut staple fibers were then washed with acidic water into the CS2 tank of the washing track for post-treatment.

As an alternative to injection wet cutters, dry cutters are used, which are horizontal discs with fixed knives. The cable is wrapped around the disc and cut by pressing the second disc towards the knife.

Post-treatment

The different stages of the process are fluff formation, treatment with acidic water, desulphurization, bleaching, washing and finishing (refining). The process is carried out on an enclosed washing track, which may be a belt or an eccentric conveyor, which conveys the fiber fluff through the aftertreatment, during which it is rinsed with different liquids. The press rollers between the washing zones reduce the entrainment of chemicals.

The staple from the cutter was washed into a CS2 tank and treated with hot acidic water. When the residual CS2 is released and subsequently recovered from the exhaust gas, the short fibers open and form fluff, which is picked up by the scrubbing track. The uniformity of the fluff is critical for uniform fiber quality.

In the first zone, residual sulfide compounds are removed by treatment with hot acidic water. After pressing, the fluff was washed with soft water in a counter-current. Fresh water is added before finishing and reused for washing after bleaching, after desulphurization and after acid treatment.

Desulfurization is carried out by treatment with a dilute caustic soda and sodium sulfide mixture to dissolve and remove sulfur residues.

Sodium hypochlorite is used as a bleaching chemical.

Before the final finishing step, the fluff is washed with soft water and dewatered with high-pressure rollers in order to reduce the liquid intake (intake) into the finishing zone to and achieve maximum finishing absorption.

Finishing is an important process for preparing the surface of fibers for further processing in yarn spinning or non-woven processes. The different components are mixed to obtain an optimal balance between adhesion, slip and antistatic properties.

After finishing, the fluff was dewatered with a high pressure roller to minimize the water content before drying. Compact wet fiber mats require a wet opening process that is performed in two or three stages using spiked rollers of different strengths to prevent fiber damage. The wet opened fibrous fluff can now be dried.

Drying, opening and packaging

Drying can be carried out in a belt dryer or drum dryer with hot air in countercurrent. The screen drum dryer consists of a series of rotating drums, each of which contains a wire jacket and a fan. Hot air is drawn into the drum interior through the fluff, which dries and presses the fluff onto the wire sleeve. By blocking half of the drum cylinder, fluff is transferred to the next drum and turned over. After passing through the first zone of the dryer, the fluff is opened again to obtain a uniform moisture profile and rearranged for the final dryer zone. At the end of the drying process, the fibers are rewetted to adjust the fiber moisture to the desired level. After drying has been completed, the final opening process is carried out in one or two stages to produce a uniform and large quantity of product ready for packaging.

Spinning bath degassing and filtration

During spinning, CS2 and H2S dissolved in the spinning bath and needed to be removed by degassing. By spraying the spinning bath in a degasser under vacuum, the gas is released and used as rich gas to produce sulfuric acid.

After filtering the degassed spinning bath through sand or candle filters, the composition of the spinning bath is adjusted by the dosage of sulfuric acid and zinc sulfate and returned to the bottom tank of the spinning bath cycle.

Evaporation of

During spinning, the spinning bath is diluted by the water taken in from the viscose and the water formed by neutralization of NaOH with sulfuric acid. In order to maintain the desired spin bath concentration, excess water must be removed by a thermal multistage evaporation device. The high efficiency flash evaporator operates at low specific steam consumption.

Crystallization of

In the modal process with a high base ratio, the amount of sodium sulfate formed by the neutralization reaction is significant. The process by-products must be removed and recovered from the spinning bath.

This is accomplished by a crystallizer that uses caustic soda or sulfuric acid as a vapor absorption method to cool the temperature of the spinning bath. Crystals of mirabilite (Na 2SO4 x 10H 2O) were grown in large drums and separated by propeller centrifuges.

Calcination of

In order to make sodium sulfate transportable and usable, the crystal water of mirabilite needs to be removed. For this purpose, pressure calcination is used. After melting the salt cake, the melt was directed through a calcination evaporator. The crystals were thickened by a second set of centrifuges and then separated. The anhydrous sodium sulfate is dried, stored and packaged.

Recovery of CS2 by condensation

Water vapor, a mixture of CS2 and H2S, was drawn from the fluff forming unit. Most of the vapor is condensed and returned to the CS2 tank. The remaining gas passes through the condenser and is sucked out by the water jet, wherein CS2 is condensed by cold water. The separator after the water jet separates the process water and condensed CS2 from the uncondensed gases. The uncondensed gases are drawn off to an exhaust system for further processing to sulfuric acid. The liquid CS2 is separated in the settler and recycled to the viscose process without any additional cleaning.

Recovery of CS2 (CAP) by adsorption

The CS2 off-gas having a low concentration of H2S was recovered by the CAP process (carbon adsorption plant). It is a batch process with cycles of adsorption and desorption of CS2 by activated carbon. Prior to applying the adsorption process, H2S had to be removed from the feed gas with NaOH in a gas scrubber. The obtained mixture of NaOH and Na2S can be used in the desulfurization process of the fiber post-treatment. The feed gas concentration should be high but must be outside the explosion limits. The liquid CS2 from desorption can be directly recycled into the process.

WSA (Wet sulfuric acid equipment)

Among all the technologies used for treating sulfide off-gases, the WSA process is most versatile and effective in removing sulfide odor by converting CS2 and H2S into sulfuric acid, which can be used in the spinning process. By combining WSA with the condensation process, a reasonable amount of CS2 input can be recycled while achieving maximum purification efficiency. However, the economic disadvantage is that the valuable specialty chemical (CS 2) is converted into the inexpensive commodity (sulfuric acid). Depending on the exhaust gas composition, additional sulfur and fuel (natural gas, oil) are used as additional inputs and steam is produced as a byproduct.

The lean gas from spinning, the rich gas from degassing the spinning bath and sulfur were used as separate feeds for WSA. The sulfide compound is efficiently converted to sulfuric acid by the catalyst.

Zinc recovery

In the work-up, zinc is precipitated from the overflow waste water of the pickling system in the form of zinc sulphide. The zinc sulphide is separated from the slurry and dissolved with sulphuric acid to obtain again zinc sulphate, which is metered into the spinning bath for the spinning process.

Disclosure of Invention

One of the key elements of modal fiber spinning is the delayed and carefully balanced coagulation/regeneration process, which achieves high drawing of the tow to have high orientation of the cellulose chains, which is essential to obtain modal fibers with excellent tensile properties. Another feature of the modal process is the lower spinning speed, which results in lower productivity per spinning position. This can be partially compensated for by a spinneret with a greater number of holes and a larger diameter.

However, most of the process parameters that are advantageous for obtaining excellent tensile properties increase the risk of spinning defects, since the thin skin of the freshly spun filaments is still very weak and may break during drawing. These parameters need to be carefully balanced to obtain fibers with the desired physical parameters without spinning defects.

Finding the proper balance becomes more difficult if the degree of filament regrowth within a tow or between tows varies widely. In this case, it is necessary to adopt spinning conditions to ensure that spinning defects are avoided without lowering the tensile strength and reducing the tensile strength.

It has surprisingly been found that this problem can be solved by providing a process for producing modal fibers, which process comprises at least the following process steps:

a. preparing alkali cellulose from a cellulose raw material,

b. the alkali cellulose is aged and the resultant is then,

c. the mixture is subjected to xanthation and acidification,

d. the mixture is dissolved and then is added with water,

e. curing, filtering, degassing,

f. spinning, wherein one or more spinnerets are used,

g. stretching the mixture to obtain a stretched mixture,

h. post-processing (including cutting, drying, opening, packaging),

i. the recovery of the chemicals is carried out by,

wherein in the spinning step, the new spinning bath is uniformly distributed along the plate of the spinning machine and across the cluster spinneret.

The concentration of sulfuric acid in the spinneret can be analyzed by sampling and titration using a thin-walled tube on the spinneret plate between the cups. The process can obtain a sulfuric acid concentration profile across the entire spinneret surface. For the manufacture of modal fibres using spinnerets with a diameter greater than 22 cm, it is of utmost importance that the sulphuric acid in the spinning bath is distributed evenly across the entire spinneret surface (from bottom to top and from outside to inside).

In the conventional diagonal spinning technique, a new spinning bath is fed at the bottom of the slot below the spinneret. The tufted spinneret, having cups arranged at equal distances, is positioned at an angle relative to the bottom of the slot, thus extruding filaments toward the surface of the spinning bath. This means that the flow directions of the spinning bath and the filaments cross each other. The new spin bath flows upstream at the back of the spinneret without contacting the filaments, or passes directly through the filaments where the sulfuric acid is consumed. In this case, the supply of fresh spinning bath for the upper part of the spinneret and for the centrally positioned cup is reduced, and the sulfuric acid concentration there is much lower than that of the bottom of the spinneret.

One solution to this problem is to use a deflector that can be fixed to each spinning tube and prevent the new spinning bath from flowing upstream on the back of the spinneret by directing it to the upper region of the spinneret. Alternatively, the deflector may be fixed in the spinning bath, preferably on the front side of the spinning bath. Combined with a specific spinneret design, where the cups are arranged such that the new spinning bath flows easily to the center, a much better sulfuric acid distribution can be achieved.

Preferably, by providing a spinning bath and a spinning bath feed system, in particular by installing a separate spinning bath inlet for each spinning position (i.e. each spinneret), the spinning bath can be distributed evenly along the spinning machine. In another preferred embodiment, each spin bath inlet has its own spin bath feed pump to achieve uniform spin bath feed to each spinneret.

Modal fibers can also be made by vertical spinning. In this case, the flow direction of the spinning bath and the filaments is the same. By arranging the bushing cups in areas separated by radial channels (which facilitate the flow of new spinning bath to the center), the uniformity of the acid distribution can be significantly improved.

Instead of using a full plate tufted spinneret, a ring spinneret can be used to make modal fibers. One preferred form of this spinneret design is a ring spinneret in which the cups are arranged on an annular plate with a hole in the center so that the new spinning bath is evenly distributed across the annular plate and flows in the same direction as the filaments. Such a ring spinneret preferably contains 2 or 3 concentric circular arrays of spinneret cups (i.e., rings). The new spinning bath is also supplied from holes in the center of the cluster spinneret, which provides an almost perfect sulfuric acid distribution across the entire spinneret. Such a ring spinneret can be used in diagonal as well as vertical spinning processes.

Typical process parameters are as follows:

the spinneret design can be a full plate circular spinneret with cups arranged equidistant from each other or a ring spinneret with cups arranged in 2 or 3 concentric circles. The diameter of each cup may be between 12 and 16mm, with the hole diameter depending on the fibre titre.

In a preferred embodiment of the invention, a full plate tufted spinneret with a diameter of more than 20 cm, a spinning cup and more than 80000 holes is used, and the spinning cup is symmetrically arranged on the spinneret in more than four zones with radial channels between the zones. In preferred embodiments of the invention, the number of holes may be as high as 120000, 150000 or even 180000 and the number of sections may be as high as 8 or 12.

In a particularly preferred embodiment, the tuft nozzles are used according to the diagonal spinning method with an immersion length of less than 50 cm and the flow guide plates are fixed on the spinning tube or in the spinning bath. In a preferred embodiment of the invention, the immersion length may be at least 35 cm.

In another particularly preferred embodiment, the full-plate tufted spinneret is used according to the vertical spinning process with an immersion length of 50 to 80 cm.

In another preferred embodiment of the invention, a ring spinneret with a diameter of more than 20 cm, with a spinning cup and holes exceeding 80000 is used, and the spinning cup is arranged in 2 or 3 concentric circles on the spinneret.

Particularly preferably, the ring spinneret is used according to the diagonal spinning method with an immersion length of less than 50 cm and wherein the flow guide is fixed on the spinning tube or in the spinning bath. In a preferred embodiment of the invention, the immersion length may be at least 35 cm.

In another particularly preferred embodiment, the ring spinneret is used according to the vertical spinning process with an immersion length of 50 to 80 cm.

Another aspect of the invention is a spinning machine suitable for incorporation in an apparatus for producing modal fibers comprising at least the following method steps:

j. preparing alkali cellulose from a cellulose raw material,

k. the alkali cellulose is aged and the resultant is then,

l, xanthating, acidifying,

m, dissolving the raw materials,

n, curing, filtering, degassing,

spinning, wherein one or more spinnerets are used,

p, stretching the mixture,

q. post-treatment (including cutting, drying, opening, packaging),

r. recovering the chemical product,

wherein the spinning machine comprises a spinning bath and a spinning bath feed system for uniform distribution along the spinning machine and spinneret, arranged such that uniform spinning bath distribution across the plates of the tufted spinneret is achieved. This can be achieved, for example, by installing a separate spinning bath inlet at each spinning position (i.e., each spinneret). In another preferred embodiment, each spin bath inlet has its own spin bath feed pump to achieve uniform spin bath feed to each spinneret. This embodiment can be further improved by installing a guide means which guides the spinning bath stream in a uniform manner across the plates of the tufted spinneret. Such guiding means may be a deflector or similar. In another preferred embodiment, each spin bath inlet is fed by its own spin bath pump to enable individual control of the spin bath stream for each spinneret.

In a preferred embodiment of the invention, the spinning machine comprises a full plate tufted spinneret having a diameter of more than 20 cm, having a spinneret cup and more than 80000 holes, and wherein the spinneret cup is symmetrically arranged on the spinneret in more than four zones, with radial channels between the zones.

In a particularly preferred embodiment of the invention, the entire plate-tuft spinneret is arranged in a spinning bath in such a way as to be able to carry out a diagonal spinning process with an immersion length of less than 50 cm, and wherein the flow guide plate is fixed on the spinning tube or in the spinning bath.

Preferably, the entire plate of the tufted spinneret is arranged in a spinning bath in such a way as to enable a vertical spinning process with an immersion length of 50-80 cm.

In another preferred embodiment, the spinning machine comprises a ring spinneret having a diameter of more than 20 cm, having a spinneret cup and more than 80000 holes, and wherein the spinneret cup is arranged on the spinneret in 2 or 3 concentric circles.

In a particularly preferred embodiment of the invention, the annular spinneret is arranged in the spinning bath in such a way that a diagonal spinning process with an immersion length of less than 50 cm is possible.

Preferably, the annular spinneret is arranged in a spinning bath such that a vertical spinning process can be carried out with an immersion length of 50-80 cm.

Drawings

Fig. 1 shows a spinning machine according to the invention: the spinning bath (1) contains a spinning bath liquid (2). New spinning bath liquid flows into the spinning bath (1) from the bottom (3). The spinning solution is fed through a spinning tube (4) to a spinneret (5). In the embodiment according to fig. 1, the deflector (6) is mounted in the spinning bath (1), fixed on the inner wall of the spinning bath (1). A bundle of freshly spun filaments (7) is extruded by the spinneret (5) and drawn through the spinning bath (2), where the coagulation of the cellulose takes place.

Claims

1. A method of manufacturing modal fibers, comprising at least the following method steps:

a. preparing alkali cellulose from a cellulose raw material,

b. the alkali cellulose is aged and the resultant is then,

c. the mixture is subjected to xanthation and acidification,

d. the mixture is dissolved and then is added with water,

e. curing, filtering, degassing,

f. spinning, wherein one or more spinnerets are used,

g. stretching the mixture to obtain a stretched mixture,

h. post-processing (including cutting, drying, opening, packaging),

i. the recovery of the chemicals is carried out by,

wherein in the spinning step, the sulfuric acid of the spinning bath is uniformly distributed across the plates of the spinneret.

2. The process of claim 1, wherein a full plate tufted spinneret of diameter greater than 20 cm, having a spinneret cup and over 80000 holes is used as the spinneret, and wherein the spinneret cup is symmetrically arranged on the spinneret plate in more than four zones with radial channels between the zones.

3. The process of claim 2, wherein the full plate tufted spinneret is used according to the diagonal spinning process with an immersion length of less than 50 cm, and wherein a flow deflector is fixed on the spinning tube or in the spinning bath.

4. The process according to claim 2, wherein the full plate tufted spinneret is used according to the vertical spinning process with an immersion length of 50-80 cm.

5. The process of claim 1, wherein a ring spinneret with a diameter of more than 20 cm, a spinneret cup and more than 80000 holes is used as spinneret, and wherein the spinneret cup is arranged on the spinneret in 2 or 3 concentric circles.

6. The process according to claim 5, wherein the ring spinneret is used according to the diagonal spinning process with a dip length of less than 50 cm, and wherein a flow deflector is fixed on the spinning tube or in the spinning bath.

7. The process according to claim 5, wherein the ring spinneret is used according to the vertical spinning process with an immersion length of 50-80 cm.

8. The process of claim 1, wherein the spinning machine comprises a spinning bath and a spinning bath feed system for uniform distribution along the spinning machine.

9. The process according to claim 8, wherein each spinning position has a separate spinning bath inlet, preferably with its own spinning bath feed pump, to achieve uniform spinning bath feed per spinneret.

10. A spinning machine suitable for incorporation in an apparatus for producing modal fibres comprising at least the following method steps:

a. preparing alkali cellulose from a cellulose raw material,

b. the alkali cellulose is aged and the resultant is then,

c. the mixture is subjected to xanthation and acidification,

d. the mixture is dissolved and then is added with water,

e. curing, filtering, degassing,

f. spinning, wherein one or more spinnerets are used,

g. stretching the mixture to obtain a stretched mixture,

h. post-processing (including cutting, drying, opening, packaging),

i. the recovery of the chemicals is carried out by,

wherein the spinning machine comprises a spinning bath and a spinning bath feed system for uniform distribution along the spinning machine and spinneret, arranged such that uniform spinning bath distribution across the plates of the spinneret is achieved.

11. The spinning machine of claim 10, wherein the full plate tufted spinneret has a diameter greater than 20 cm, has a spinneret cup and more than 80000 holes, and wherein the spinneret cup is symmetrically arranged on the spinneret in more than four zones with radial channels between the zones.

12. A spinning machine according to claim 11, wherein the full plate tuft spinneret is arranged in the spinning bath so as to enable a diagonal spinning process with an immersion length of less than 50 cm, and wherein the flow deflector is fixed on the spinning tube or in the spinning bath.

13. The spinning machine according to claim 11, wherein the entire plate of tufted spinneret is arranged in the spinning bath such as to enable a vertical spinning process with an immersion length of 50-80 cm.

14. The spinning machine of claim 10, wherein the ring spinneret has a diameter greater than 20 cm, has a spinneret cup and more than 80000 holes, and wherein the spinneret cup is arranged on the spinneret in 2 or 3 concentric circles.

15. The spinning machine according to claim 13, wherein the annular spinneret is arranged in the spinning bath such that a diagonal spinning process can be carried out with an immersion length of less than 50 cm, and wherein the flow deflector is fixed on the spinning tube or in the spinning bath.

16. The spinning machine according to claim 13, wherein the annular spinneret is arranged in a spinning bath such as to enable a vertical spinning process with an immersion length of 50-80 cm.

17. A spinning machine according to claim 10, wherein each spinning position has a separate spinning bath inlet, preferably with its own spinning bath feed pump, to achieve uniform spinning bath feed to each spinneret.