DE102014109786A1 - Process for the production of moldings - Google Patents

Abstract

In a process for producing molded articles from a matrix substance, which is mixed with a solvent to produce a molding solution and then this solvent is at least partially removed from the molding solution and the molding solution is supplied to a device (8) for molding, the molding solution is a cylindrical in cross-section or eight-shaped thick-film solvent or a combination of a thin-film evaporator, which is cylindrical in cross-section, and a cylindrical or eight-shaped thick-film solvent.

Description

The present invention relates to a process for the production of molding solution from a matrix substance, which is mixed with a solvent to prepare a molding solution, and then this solvent is at least partially removed from the molding solution and the molding solution is fed to a molding apparatus.

STATE OF THE ART

In the present case, the term "shaped body" encompasses all sorts of bodies that are made of a natural or artificial basic substance, usually with the aid of a molding tool that transforms the basic substance into a mold for the shaped bodies but not by way of limitation or limitation, the lyocell and viscose fibers are to be mentioned.Lococell / viscose fibers are fibers which consist of the base material cellulose and are industrially produced by a dissolving process followed by spinning.Some of the molded articles require a high quality of the molding solution. to meet the quality requirements of the molded article, eg the filament The chemical nature of the viscose / lyocell fibers is similar to that of cotton fibers.

The shaped articles are, for example, staple fibers, non-wovens such as nonwoven, hybrid fibers, functionalized fibers and filaments (fibers with a length of far more than 1 meter). They consist of 100% cellulose and, like viscose fibers, are made from natural pulp. Moldings such as filaments can be used for example as a precursor for further processing into carbonized fibers. Hybrid fibers or hybrids are fibers of a mixture of different starting materials, such as cellulose and PAN (polyacrylonitrile), cellulose and thermoplastics, or cellulose and polymers. These starting materials can either be dissolved together as a molding solution or only mixed. For functionalized fibers, functional materials such as silver, paraffin, or carbons are added before, during, or after the dissolution process to affect the property of the fiber.

In the lyocell fibers, the pulp is dissolved directly and unchanged by the non-toxic solvent NMMO (N-methylmorpholine-N-oxide) without prior reaction with sodium hydroxide solution and derivatization to the xanthate. The spinning of the lyocell fibers takes place in a dilute, aqueous NMMO bath, whereby the solubility limit of the cellulose falls below and thereby a thread is formed. For this purpose, the appropriate molding solution is forced through spinnerets. This Lyocell method is used for example in the DE 1 713 486 . U.S.-A-3,447,939 or GB 8 216 566 described. The preparation of the appropriate molding solution is carried out, for example, in a cylindrical, vertically operating thin-film solvent (Filmtruder), as for example in GB 08 / 875,437 or US 5,888,288, A or a horizontally operating Dickschichtlöser (kneading reactor), as described in the DE 198 37 210 or the WO 02/20885 A1 is shown.

In these devices and according to the known methods, the molding solution is prepared in the further processable viscosity and the associated cellulose concentration necessary for the spinning process.

Both devices for the production of the forming solution for the production of lyocell fibers are not optimally suited for the entire dissolving process of the basic material pulp in the solvent NMMO. The vertical thin film dissolver has good heat transfer, but a short residence time, which does not allow the necessary swelling of natural fibers and the necessary homogenization for a perfect mold solution. The horizontal thick-film solvent realizes a longer residence time, which leads to a good penetration of the solvent into the fiber and thus a good homogenization for a very good molding solution.

However, both devices are still used today for the production of the molding solution for the lyocell fibers in the industry. Due to the suboptimal conditions described above, the solvers for both processes are getting bigger and larger and are limited by their maximum size. Larger line capacities of more than 50 t of fibers per day are thus not feasible with these devices. Capacities of 100 t of fibers per day and production line are necessary to make this technology more efficient in the long term and thus competitive with viscose fiber or modal fiber.

Some shaped articles, such as filaments, hybrid fibers and functionalized fibers require a very high quality molding solution that can not be produced by a thin film evaporator alone.

TASK

The present invention is based on the object, the o.g. To optimize processes in such a way as to be able to realize larger capacities, for example of more than 100 t of fibers per day and production line.

In addition, the present invention has for its object to produce a quality solution to form filaments, precursors for carbonized fibers, hybrid fibers and functionalized fibers.

SOLUTION OF THE TASK

To achieve the object, that the molding solution is fed to a cylindrical or achtförmigen Dickschichtlöser or a combination of a cross-sectionally vertical cylindrical thin film evaporator and a horizontal cylindrical or eight-shaped Dickschichtlöser.

A thin-film evaporator is an evaporator that vaporizes solutions in a thin film. It is usually operated in a vacuum and is therefore suitable for gentle separation of mixtures. His way of working is as follows:

A liquid is passed from above to vertical evaporator surface. The evaporator surface is a tube with a mechanical stirring system in the middle. The thin solution film is formed by the stirring system with fixed or movable stirring blades which brush along the heating surface. The required evaporation energy is introduced into the solution film via an external double cladding. [1] http://de.wikipedia.org/wiki/D%C3%BCnnschichtverdampfer#cite_note-1

Since the apparatus can be operated very well in a vacuum, it is suitable for careful distillation at low temperatures. For crystallization processes, thin-film evaporators with movable stirring blades are suitable.

A thin film solvent is a derived name of a thin film evaporator. In the case of the solubilizer, in addition to the evaporation, one substance is dissolved in another, e.g. Cellulose in a solvent.

A thick-film dissolver should be understood to mean a mixing kneader in which, in contrast to the thin-film solvent, the medium to be evaporated is not vaporized in a thin film, but via surface renewal of a thick layer. The terminology is chosen to identify the contrast to a thin-film solvent. Solvent and medium (cellulose) is brought together by a kneading and shearing action.

Preference is given to a horizontal, in cross-section cylindrical or achtförmiger thick-film solvent or a combination of a vertical cylindrical thin-film evaporator in cross-section and a horizontal in cross-section cylindrical or eight-shaped Dickschichtlöser. The thick-film solvents are above all so-called mixing kneaders, which can be single-shaft or double-shaft. Essentially, a single-shaft and two-shaft mixing kneader are distinguished. A single-shaft mixing kneader with horizontally arranged shaft, for example, in the EP 91 405 497.1 described. Multi-shaft mixing and kneading machines with achtförmigem in cross section housing are in the CH-A 506 322 , of the EP 0 517 068 B , of the DE 199 40 521 A1 or the DE 101 60 535 is described. There are located on a horizontally arranged shaft radial disc elements and arranged between the discs axially aligned kneading. Between these discs engage from the other horizontally arranged wave frame-like shaped mixing and kneading elements. These mixing and kneading elements clean the disks and kneading bars of the first shaft. The kneading bars on both shafts in turn clean the inside of the housing.

The dissolution process was analyzed on the basis of the basic pulp pulp in NMMO process technology on the basis of the two known devices. It was found that the dissolution process can be divided into three sections, which require very different process conditions. In the first section, the evaporation of water from a pulp-solvent suspension (also called mash) takes place up to the starting point of the dissolution of the pulp, which the achievement of the release window, ie those conditions under which the cellulose dissolves in the aqueous NMMO, and thus approx which corresponds to 2.5 times the hydrate of the NMMO. This section requires a lot of heat energy to evaporate the water, but does not require additional residence time because the pulp is not yet dissolved, and the viscosity of the suspension is low.

After reaching the dissolving window, the main dissolution takes place in the second section with a strong increase in viscosity and the necessary low evaporation of water up to 1.5 times the hydrate of the NMMO.

The third section is determined by the homogenization of the spinning solution and also lower water evaporation to about 0.8 to 1.0 times the hydrate depending on the pulp concentration.

The process engineering evaluation shows now in connection with the devices used for the Lösestufe that the thin film evaporator due to the good heat transfer very well for the large water evaporation at low viscosity and short residence time in the first section and the thick film evaporator or kneading reactor due to the very good homogenization, the longer residence times and the processing of higher viscosities and the lower Water evaporation for the second and third section is suitable.

Both devices are linked so that the product spaces are directly connected to each other, whereby the transfer point is located as a complicated interface inside and thus eliminates the transfer of sometimes changing product consistencies. Variations in a small holdup of the thin-film solvent can easily be compensated by the thick-film evaporator or kneading reactor. In some cases, however, a separation of the apparatuses is required in order to be able to realize different process conditions (for example, vacuas).

In a preferred embodiment of the invention, the thin film evaporator is preceded by a mixer in which the ground substance, i. in particular cellulose, is premixed with the solvent. This results in an intensively mixed mash. As a mixer, a horizontal kneading reactor is preferably used here.

For complete dissolution of the pulp in NMMO, it has been found that the dissolution process requires a high residence time and intensive mixing and incorporation of shear to produce a high quality mold solution. The dissolution with pulp concentrations of up to 36% by weight (concentration of the pulp in the molding solution) additionally helps to produce a high quality of the molding solution. The MasterConti process can be used to set the appropriate optimum molding viscosity (e.g., spinning) by dilution.

The process engineering evaluation now shows, in connection with the devices used for the dissolution stage, that the horizontal, cylindrical or eight-shaped thick-film solvent or the above-described combination of thin and thick-film solvent is excellently suited for the production of high-quality molding solution.

To further increase the capacity of the process was already in the WO 2009/098073 explained concentrated solution included in the consideration. It is thus possible to combine the two-stage preparation of the spinning solution with a concentrated solution of cellulose with subsequent recovery and thus to achieve a further increase in efficiency.

As with the WO 2009/098073 the concentration of the molding solution and / or the thinner should be controlled by the optical index (refractive index). This is done with the diluent before introduction into the molding solution and / or with the molding solution after dilution. An optical index of the diluent and / or the molding solution in the range from 1.45 to 1.52 is desired.

As the solvent or diluent, an aqueous tertiary amine oxide is preferably used. However, the invention should not be limited thereto. Also, the invention is not limited to pulp, but also includes substances such as proteins, polylactides, polyacrylonitrile (PAN) or starch or a mixture of these substances, whereby hybrid fibers or composite arise.

In the present process, it is of minor importance which molding is produced. Preferably, filaments, nonwovens or filament yarn are produced. However, it is also possible to produce hybrid fibers, functionalized fibers, films, hollow fibers, membranes or the like. The formation of the solution into a desired cellulosic molding can be carried out with known spinnerets for the production of fibers, slot dies or hollow thread spinnerets. Following formation, i.e., prior to introduction of the shaped solution into the coagulation bath, it may also be stretched.

To produce the desired quality of the molded body, it is possible that the fiber is not or not completely dried after molding and little to no stretching. This production feature after creating the molding solution allows the molding to dry out without tension.

DESCRIPTION OF THE FIGURES

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; this shows in its single figure a block diagram of a process according to the invention for the production of moldings from a basic substance, in particular from renewable raw materials.

The cellulose or premixed cellulose mash is required via a supply line 1 a thin film evaporator 2 fed. Such vertical cylindrical apparatuses are for example from GB 08 / 875,437 or US 5,888,288 known. Optionally, the cellulase mash also the kneading reactor 4 be fed directly.

In the thin-film evaporator 2 when used, the suspension is concentrated. From there, the concentrated suspension is directly into a thick-film solvent, preferably a horizontal kneading reactor 4 , to hand over. These kneading reactors are for example from DE 199 40 521 A1 or the DE 41 18 884 known. However, this thin-film evaporator and these kneading reactors is not limited the invention. The invention encompasses all treatment devices in which renewable raw materials can be subjected to a treatment for a later shaping.

In the present embodiment, the treatment of the renewable raw material by means of a solvent, preferably an aqueous tertiary amine oxide, which was previously mixed as Zellulosemaische and, accordingly, in the supply line 1 is fed to the thin-film evaporator. Optionally, the cellulase mash also the kneading reactor 4 be fed directly.

In the thin-film evaporator 2 takes place with addition of heat, a water evaporation from the suspension, without dissolving the pulp.

In the kneading reactor 4 takes place with addition of heat, an intensive mixing of the raw material with the solvent, a partial evaporation of the water from the solvent and thus the dissolution of the pulp, so that a relatively high-viscosity molding solution is formed. This molding solution is then discharged via a discharge device 5 the spinning plant 8th fed.

The production of a molding solution in a kneading reactor or the described combination of thin-film evaporator and kneading reactor results in a high quality ground substance for subsequent spinning into a filament, staple fiber or nonwoven by a wet spinning process, which is primarily but not necessarily carried out by an air gap.

The relatively high viscosity molding solution may be diluted to a spinnable molding solution prior to final processing into fibers. This happens in the discharge device 5 via a supply line 6 or even before the discharge device 5 in the kneading reactor 4 at any point and / or split. This procedure was confirmed in experiments. Also, a combination of both addition sites is possible if the dilution ratio is very high.

After the discharge device 5 and in front of the spinning plant 8th is a pump 7 switched on, by means of which the molding solution is stowed after the discharge. The process according to the invention is carried out as follows:

About the supply line 1 the input of the suspension, consisting of the basic substance, in particular of the renewable raw material, and the solvent in the thin-film evaporator 2 or directly into the kneading reactor 4 , With the addition of heat from the outside by means of a heating jacket takes place an intense evaporation of water from the suspension to the release window, without starting the solution of the ground substance.

The concentrated suspension is removed from the thin-film evaporator 2 through a direct transition 3 discharged directly or via a pump or valve and into the thick-film solvent 4 entered. In the thick-film solvent 4 , in which the basic substance can also be registered directly, a kneading reactor, intensive mixing is carried out optionally also the evaporation of water until reaching the release window, wherein the heat addition from the outside by means of a heating jacket, by heated kneading and / or by heated kneading (disk elements) done can. Another mechanical heat input occurs during mixing itself by the corresponding shear energy. Due to the intensive mixing and the registered shear energy, the basic substance is completely dissolved and a high quality forming solution is created.

By evaporating a portion from the solvent, the suspension is converted into a molding solution (molding solution) and further concentrated so that it is towards the end of the kneading reactor 4 just before the discharge facility 5 has a proportion of 8 to 36% of ground substance. This molding solution may be too viscous for later spinning. It is now, if required by the spinning process requirements, diluted with a thinner which passes through the supply line 6 is supplied. The concentration of the molding solution is controlled before and / or after the addition of the diluent via the optical index. This optical index is also called the refractive index. It marks the refraction (change of direction) and the reflection behavior (reflection and total reflection) of electromagnetic waves when hitting an interface between two media.

Furthermore, it is thought, before the discharge or in the discharge, possibly also via the supply line 6 to add an additive to the mold solution / mixture. An additive or an additive mixture can also be supplied together with the diluent.

In the thin-film evaporator 2 or in the kneading reactor 4 resulting vapors are via a Gastraumverbindung 9 a condensation 10 fed. LIST OF REFERENCE NUMBERS 1 supply 2 thin film evaporator 3 crossing 4 kneading reactor 5 discharge 6 supply 7 pump 8th spinning plant 9 Guest room connection 10 condensation

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 1713486 [0004]
• US 3,447,939 A [0004]
• GB 8216566 [0004]
• GB 08/875437 [0004, 0032]
• US 5888288 A [0004]
• DE 19837210 [0004]
• WO 02/20885 A1 [0004]
• EP 91405497 [0017]
• CH 506322 A [0017]
• EP 0517068 B [0017]
• DE 19940521 [0017]
• DE 10160535 [0017]
• WO 2009/098073 [0026, 0027]
• US 5888288 [0032]
• DE 19940521 A1 [0033]
• DE 4118884 [0033]

Cited non-patent literature

• http://en.wikipedia.org/wiki/Drying_plates_cite_note-1 [0013]

Claims (17)

Process for the production of moldings from a matrix substance, which mixes with a solvent for producing a molding solution and then at least partially removes this solvent from the molding solution and the molding solution of a device ( 8th ) is supplied for molding, characterized in that the molding solution is a cylindrical or eight-shaped Dickschichtlöser ( 2 ) or a combination of a cylindrical thin film evaporator ( 2 ) and a cylindrical or eight-shaped thick-film solvent ( 4 ) is supplied. A method according to claim 1, characterized in that the solvent is an aqueous tertiary amine oxide. A method according to claim 1 and 2, characterized in that the mixture of the base substance and the solvent is stored in a stirred container and the container functions as a dosing template. A method according to claim 1 to 3, characterized in that the ground substance is a renewable raw material such as cellulose, starch or the like or a mixture of the renewable raw material and a synthetic material such as PAN (polyacrylonitrile), TPE (thermoplastic elastomer) or polymer. A method according to claim 1 to 4, characterized in that the thin-film evaporator ( 2 ) optionally absorbs the suspension of the base substance and solvent and concentrated by evaporation of water to a preliminary state of about 2.5 hydrate of a tertiary amine oxide. Method according to at least one of claims 1 to 4, characterized in that the thick film solvent ( 4 ) the suspension from the thin-film evaporator ( 2 ) or the suspension is absorbed directly and concentrated by evaporation of water to about 0.5 to 1.5 hydrate, dissolved and homogenized in a molding solution. Method according to at least one of claims 1 to 5, characterized in that the thin-film evaporator ( 2 ) and / or the thick film solvent ( 4 ) at 80 ° to 180 ° C, preferably at 100 ° to 150 ° C, operated / are. Method according to at least one of claims 1 to 6, characterized in that the thin-film evaporator ( 2 ) and / or the thick film solvent ( 4 ) is operated under a vacuum of 20 to 200 mbar absolute, preferably below 30 to 100 mbar absolute. Method according to at least one of claims 1 to 7, characterized in that a permanent temperature control along the axes of thin film evaporator ( 2 ) and / or thick-film solvent ( 4 ) he follows. Method according to at least one of claims 1 to 8, characterized in that the molding solution is controlled by means of an optical index which is between 1.47 and 1.52, preferably between 1.48 and 1.50. Method according to at least one of claims 1 to 9, characterized in that the molding solution is rediluted to the viscosity necessary for spinning. Method according to at least one of claims 1 to 10, characterized in that the molding solution has a quality which is necessary for the production into a shaped body, such as filaments. A method according to at least one of claims 1 to 11, characterized in that the molding solution is deformed by a wet spinning process, wherein the molding solution is spun by priority, but not mandatory, an air gap or directly from the spinning bath. Method according to at least one of claims 1 to 12, characterized in that the shaped body, in particular, but not limiting, filaments, washed after spinning from the spinning bath, but not or not completely dried and little to no stretched. A method according to any one of claims 1 to 13, characterized in that the diluent is an aqueous tertiary amine oxide. Device for carrying out the method according to at least one of claims 1 to 14, characterized in that the thin-film evaporator ( 2 ) and / or the thick film solvent ( 4 ) are directly connected to each other via their product space or operated separately in the optimal vacuum range. Apparatus according to claim 11, characterized in that the thin-film evaporator ( 2 ) and / or the thick film solvent ( 4 ) are directly connected to each other via their gas space or are separated from each other by a suitable separating member such as a valve or a pump.

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