EP0608744B1 - Cellulose acetate filaments, an optically isotropic spinning solution therefor and its use for the production of the filaments - Google Patents

Cellulose acetate filaments, an optically isotropic spinning solution therefor and its use for the production of the filaments Download PDF

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Publication number
EP0608744B1
EP0608744B1 EP94100584A EP94100584A EP0608744B1 EP 0608744 B1 EP0608744 B1 EP 0608744B1 EP 94100584 A EP94100584 A EP 94100584A EP 94100584 A EP94100584 A EP 94100584A EP 0608744 B1 EP0608744 B1 EP 0608744B1
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EP
European Patent Office
Prior art keywords
spinning solution
filaments
cellulose acetate
degree
acetone
Prior art date
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EP94100584A
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German (de)
French (fr)
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EP0608744A1 (en
Inventor
Ties Dipl.-Chem. Dr. Karstens
Wolfgang Dipl.-Ing. Koppe
Joachim Dipl.-Chem. Dr. Schätzle
Günter Dipl.-Ing. Maurer
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Cerdia Produktions GmbH
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Rhodia Acetow GmbH
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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
    • D01F2/24—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives
    • D01F2/28—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate
    • D01F2/30—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate by the dry spinning process
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
    • D01F2/24—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives
    • D01F2/28—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/2964—Artificial fiber or filament
    • Y10T428/2965—Cellulosic

Definitions

  • the invention relates to filaments based on a cellulose acetate soluble in acetone, an optically isotropic spinning solution for the production of filaments, which is a cellulose acetate dissolved in acetone and optionally further additives contains, as well as the use of this spinning solution for the preparation of the designated Filaments.
  • DE-OS 27 05 382 describes an extensive group of cellulose derivatives, i.a. also cellulose acetates. These are said to be in an anisotropic spinning solution transferred to produce filaments using conventional spinning processes. According to Table I, the degree of substitution (DS) of the cellulose acetate between 1.89 to 2.45. Most suitable solvents are: halogenated and phenolic compounds specified. In connection with the other cellulose derivatives specified in DE-OS 27 05 382 Acetone is also listed in a large number of solvents. The cellulose derivatives in the spinning solution in an amount of at least 15 vol.% are available to meet the requirement for optical anisotropy.
  • DE-OS 27 05 382 In the DE-OS 27 05 382 is, however, the combination "cellulose acetate dissolved in acetone" not mentioned. And otherwise a 15 vol.% Acetone solution of the cellulose acetate described in DE-OS 27 05 382 also not optically anisotropic, but optically isotropic.
  • a cellulose acetate with a degree of substitution (DS) of 1.89 is not soluble in acetone.
  • DS degree of substitution
  • DE-OS 27 05 382 Cellulose derivatives with an average degree of polymerization (DP) of at least 100 anhydroglucose units have a sufficiently high molecular weight to be suitable for the production of filaments.
  • DE-OS 27 05 382 does not contain any precise statements on the degree of polymerization of the cellulose acetate or the degree of substitution between 1.89 and 2.45.
  • WO 94/06954 which belongs to the prior art according to Article 54 (3) EPC, discloses a method for spinning a solution in acetone of cellulose acetate with an intrinsic viscosity of preferably 1.35 (equal to a DP of 196) or more, and an acetyl content of 39.5% by weight (corresponds to a degree of substitution (DS) of 2.45).
  • the filaments have a titer of up to 1.56 dtex (1.4 denier) and contain a finely divided pigment (TiO 2 ) in amounts of less than 0.94% by weight.
  • An overall view of the prior art shows that in Connection with acetone as the solvent of a spinning solution of cellulose-2,5-acetate a high degree of polymerization of 300 is required, with the result that the spinning solution only has a low concentration of about 20 to 30% Has cellulose-2.5 acetate.
  • a starting material of this degree of polymerization can its concentration in acetone to produce a Spinning solution should not be raised further because it is inevitable sharp increase in the viscosity of the spinning solution is associated with that of usual Spinning devices can no longer be spun (for example at 40 to 50%).
  • a noticeably increased concentration would have the advantage offer that the content of acetone in the spinning solution can be drastically reduced could result in significant energy savings in circulation and recovery of acetone.
  • the invention is therefore based on the object of filaments on the basis of a cellulose acetate soluble in acetone and one especially for its production propose suitable spinning solution, which has the disadvantages described above the state of the art, especially the poor economy, fix without affecting the properties of the filaments, especially the tensile strength as well as the stretch, compared to known products become.
  • the above task is accomplished by filaments based on a soluble in acetone Dissolved cellulose acetate, which is characterized in that the degree of polymerization (DP) of the cellulose acetate is between 110 and 210. Especially the range of the degree of polymerization is preferred between 150 and 180 and especially between 160 and 180.
  • DP degree of polymerization
  • the degree of substitution (DS) is preferably set between 2.2 and 2.7. Especially it is preferred if the degree of substitution (DS) is between 2.4 and 2.6 and most preferably between 2.4 and 2.5.
  • the liter of filaments according to the invention is not critical. Preferably lies he between about 1 and 14 dtex, in particular between about 1.5 to 9 dtex. It is the fineness designation for filaments, i.e. a weight per length, the unit of which is the dtex.
  • the parameters of the filaments according to the invention are set in such a way that that their tensile strength between 0.9 and 1.2 cN / dtex, in particular between 1.0 and 1.2 cN / dtex, and the elongation between 10 and 30%, in particular between 15 and 25%. So they are enough the demands placed on the known filaments of this type, to make them suitable for the areas of application described below.
  • this optically isotropic spinning solution is characterized by that the concentration of cellulose-2,5-acetate in the spinning solution 35 to 47 mass% and the degree of polymerization (DP) of the cellulose-2,5-acetate is between 110 and 210. It is preferred here that the cellulose-2,5-acetate described above in connection with the Description of the filaments called degrees of polymerization and substitution having.
  • the optimal concentration of the cellulose-2,5-acetate in the invention optically isotropic spinning solution it is of particular advantage if its concentration (c) in the spinning solution is at most 8% by mass and in particular at most 6% by mass below the critical concentration (c *), measured at room temperature (approx. 20 ° C). Will this be critical Concentration of cellulose-2,5-acetate at higher concentrations of the spinning solution exceeded without the influence of external forces, such as shear forces (c> c *), then the spinning solution is converted from the isotropic to the anisotropic state.
  • optically isotropic spinning solution In order to further improve the optically isotropic spinning solution according to the invention, various additives can be incorporated, such as pigments and water.
  • the optically isotropic spinning solution according to the invention preferably contains up to 6% by mass and in particular 2 to 4% by mass of water. With the incorporation of water has the advantage that the viscosity of the Spinning solution reduced with the consequence of an improved spinnability becomes.
  • the spinning solution preferably contains one finely divided pigment, in particular a white pigment, such as preferably titanium dioxide.
  • the particle size is expediently in the range of about 0.3 ⁇ m to 0.5 ⁇ m.
  • the amount of fine pigment in the spinning solution is preferably 0.4 to 0.8 mass%, based on the proportion of Spinning solution on cellulose 2,5-acetate. The percentage by mass is very particularly preferred Range from about 0.4 to 0.6.
  • the advantages achievable with the invention can be described as follows:
  • the spinning mill can use an optically isotropic acetone spinning solution with a produce and spin a much higher content of cellulose-2,5-acetate, especially after the usual dry spinning.
  • filtertow In the preparation of from e.g. (Cigarettes) filtertow must be produced per unit of filtertow due to the high concentration of spinning solution much less acetone than can be recovered under the previous conditions. In this way can be, e.g. same filter tow production that with the recovery of the acetone associated costs markedly reduce.
  • the spinning mill based on the spinning solution according to the invention with the same viscosity Spinning solution produced and processed in a much higher concentration than before become.
  • the advantages mentioned above are accordingly with an optically isotropic acetone spinning solution high concentration of cellulose-2,5-acetate achieved.
  • the anisotropy or isotropy can be determined by visual inspection. An anisotropic phase looks cloudy and / or "pearly" while the isotropic phase is always clear.
  • the respective isotropic or anisotropic can also Condition of a spinning solution determined microscopically with crossed Nicols become. For example, if a sample of an anisotropic spinning solution between slide and cover glass of a microscope after pressing down of the coverslip observed between crossed Nicols is at least part of the solution is translucent.
  • the temperature also plays a role here a role; when the temperature of an anisotropic cellulose acetate solution of initially increased room temperature, then the anisotropic phase gradually change to the isotropic phase. If the temperature is increased further, the entire spinning solution is converted into an isotropic system.
  • the temperature ranges, at which these transitions take place vary depending on the type of Cellulose derivative, its concentration in the spinning solution and its Degree of substitution.
  • the possible uses of the filaments obtained according to the invention are not restricted compared to the known filaments of this type. So they can be used to manufacture filter tow (combined into a band Filament bundle), for tobacco smoke filters, especially cigarette filters, but also for example for the production of - textile - yarns for lining materials or of Blended fabrics with cotton can be used.
  • the starting point is an isotropic acetone solution of cellulose-2,5-acetate the designated species, their concentration close to the critical Concentration value (c *) can be raised, from which anisotropic Phase arises.
  • Such an isotropic solution will enter the spinneret channels (Capillaries) introduced, then cause those caused by the flow forces Shear forces in the spinneret channel that are predominantly an orientation and thus sets anisotropy.
  • the spinneret channels Capillaries
  • Fiber strengths In the area of the capillary and after exiting the isotropic phase from the capillary does not differ from a real one anisotropic phase. For this reason, you get almost the same in both cases Fiber strengths.
  • a spinning solution with the following composition was used: Dimensions-% Cellulose acetate (DP: 150; DS: 2.45) 43.2 water 3rd acetone 53.8
  • the spinning solution was spun in a conventional dry spinning system which had a nozzle plate with 125 nozzle channels.
  • the nozzle channels were triangular in cross section. The triangle had an edge length of 45 ⁇ m.
  • the nozzle temperature was 47 ° C and the nozzle pressure was 88 bar.
  • the spinning speed was 340 m / min with a draw factor of 1.6.
  • a temperature of 70 ° C prevailed in the spinning shaft with a total length of 4 m located under the spinneret. 10 m 3 of acetone-air mixture were suctioned off per hour.
  • the filaments obtained had the following physical properties: Titer 3.1 dtex tensile strenght 1.0 cN / dtex strain 19.4%
  • the 125 filaments obtained by the method of this example were combined into a filament bundle. 80 such filament bundles became one Cigarette filter tow (English: cigarette filter tow) summarized.
  • a spinning solution with the following composition was used: Dimensions-% Cellulose acetate (DP: 170; DS: 2.47) 42.1 water 3rd acetone 54.9
  • the spinning solution was spun on the same dry spinning system as in Example 1, but the nozzle plate had 240 nozzle channels.
  • the nozzle channels would be triangular in cross section.
  • the triangle had an edge length of 45 ⁇ m.
  • the nozzle temperature was adjusted to 52 ° C and the nozzle pressure was 80 bar.
  • the spinning speed was 310 m / min with a stretching factor of 1.3.
  • the temperature in the spinning shaft located under the spinneret with a total length of 4 m was 70 ° C. 10 m 3 of acetone-air mixture were suctioned off per hour.
  • the filaments obtained had the following physical properties: Titer 3.6 dtex tensile strenght 1.1 cN / dtex strain 20.5%

Abstract

There are described filaments on the basis of a cellulose acetate soluble in acetone, the degree of polymerization (DP) of the cellulose acetate being between about 110 and 210 and the degree of substitution (DS) preferably between about 2.2 and 2.7. Optically isotropic spinning solutions can be obtained, the cellulose acetate concentration of which is about 35 to 47 mass-%. When such an optically isotropic spinning solution is spun, in particular by dry spinning, filaments are obtained in a profitable manner because the costs connected with the recovery of the acetone can be appreciably lowered, without impairing the desirable properties of the filaments, which are suitable in particular for the production of cigarette filter tow.

Description

Die Erfindung betrifft Filamente auf der Basis eines in Aceton löslichen Celluloseacetats, eine optisch isotrope Spinnlösung zur Herstellung von Filamenten, die ein in Aceton gelöstes Celluloseacetat und gegebenenfalls weitere Additive enthält, sowie die Verwendung dieser Spinnlösung zur Herstellung der bezeichneten Filamente.The invention relates to filaments based on a cellulose acetate soluble in acetone, an optically isotropic spinning solution for the production of filaments, which is a cellulose acetate dissolved in acetone and optionally further additives contains, as well as the use of this spinning solution for the preparation of the designated Filaments.

Die DE-OS 27 05 382 beschreibt eine umfangreiche Gruppe von Cellulosederivaten, u.a. auch Celluloseacetate. Diese sollen in eine anisotrope Spinnlösung überführt werden, um anhand üblicher Spinnverfahren Filamente herzustellen. Nach Tabelle I soll der Substitutionsgrad (DS) des Celluloseacetats zwischen 1,89 bis 2,45 liegen. Als geeignete Lösungsmittel werden hierfür überwiegend halogenierte und phenolische Verbindungen angegeben. Im Zusammenhang mit den in der DE-OS 27 05 382 angegebenen weiteren Cellulosederivaten wird in einer großen Zahl von Lösungsmitteln auch Aceton aufgelistet. Die Cellulosederivate sollen in der Spinnlösung in einer Menge von mindestens 15 Vol.% vorliegen, um die Forderung nach optischer Anisotropie zu erfüllen. In der DE-OS 27 05 382 ist jedoch die Kombination "Celluloseacetat gelöst in Aceton" nicht erwähnt. Und im übrigen würde eine 15 vol.%ige acetonische Lösung des in der DE-OS 27 05 382 beschriebenen Celluloseacetats auch nicht optisch anisotrop, sondern optisch isotrop sein.DE-OS 27 05 382 describes an extensive group of cellulose derivatives, i.a. also cellulose acetates. These are said to be in an anisotropic spinning solution transferred to produce filaments using conventional spinning processes. According to Table I, the degree of substitution (DS) of the cellulose acetate between 1.89 to 2.45. Most suitable solvents are: halogenated and phenolic compounds specified. In connection with the other cellulose derivatives specified in DE-OS 27 05 382 Acetone is also listed in a large number of solvents. The cellulose derivatives in the spinning solution in an amount of at least 15 vol.% are available to meet the requirement for optical anisotropy. In the DE-OS 27 05 382 is, however, the combination "cellulose acetate dissolved in acetone" not mentioned. And otherwise a 15 vol.% Acetone solution of the cellulose acetate described in DE-OS 27 05 382 also not optically anisotropic, but optically isotropic.

Ferner ist ein Celluloseacetat eines Substitutionsgrad (DS) von 1,89 in Aceton nicht löslich. Dies ergibt sich aus Houben-Weyl "Methoden der organischen Chemie", Bd.E 20, Teil 3, "Makromolekulare Stoffe", Georg Thieme Verlag Stuttgart, New York, 1987, S. 2099. Nach der DE-OS 27 05 382 sollen Cellulosederivate mit einem mittleren Polymerisationsgrad (DP) von mindestens 100 Anhydroglucose-Einheiten ein hinreichend hohes Molekulargewicht aufweisen, um zur Herstellung von Filamenten geeignet zu sein. Präzise Aussagen zu dem Polymerisationsgrad des Celluloseacetats des Substitutionsgrades zwischen 1,89 bis 2,45 finden sich in der DE-OS 27 05 382 nicht. Hierauf geht Ullmann's Enzyklopedia of Industrial Chemistry, 5., vollständig überarbeitete Auflage., Vol. A5, S. 447/448 im Zusammenhang mit dem Verspinnen von in Aceton gelöstem "secondary acetate" ein. Hierunter soll das "Cellulose-2,5-Acetat" verstanden werden. Die Zahl "2,5" bedeutet die durchschnittliche Anzahl der Acetylgruppen pro Anhydroglucose-Einheit. Für die Herstellung von Fasern und Zigarettenfiltertow wird für das Cellulose-2,5-Acetat ein Polymerisationsgrad (DP) von 300 gefordert (vgl. Seite 447, Tabelle 15). Dieses soll aus einer acetonischen Lösung versponnen werden können, deren Viskosität bei einer Konzentration an Cellulose-2,5-Acetat von 20 bis 30% sowie bei einer Temperatur von 45 bis 55°C zwischen 300 und 500 Pa.s (gemeint ist wohl: ....zwischen 30 und 50 Pa.s...) liegt. Hiermit erhaltene Filamente haben die folgenden physikalischen Eigenschaften: Zugfestigkeit (cN/dtex) 1,0 bis 1,5, Dehnung (%) 25 bis 30, Dichte (g/cm3) 1,33, Schmelzpunkt (°C) 225 bis 250 und, wie bereits angegeben, einen Polymerisationsgrad von 300.Furthermore, a cellulose acetate with a degree of substitution (DS) of 1.89 is not soluble in acetone. This results from Houben-Weyl "Methods of Organic Chemistry", Vol. E 20, Part 3, "Macromolecular Substances", Georg Thieme Verlag Stuttgart, New York, 1987, p. 2099. According to DE-OS 27 05 382 Cellulose derivatives with an average degree of polymerization (DP) of at least 100 anhydroglucose units have a sufficiently high molecular weight to be suitable for the production of filaments. DE-OS 27 05 382 does not contain any precise statements on the degree of polymerization of the cellulose acetate or the degree of substitution between 1.89 and 2.45. This is discussed by Ullmann's Encyclopedia of Industrial Chemistry, 5th, completely revised edition., Vol. A5, pp. 447/448 in connection with the spinning of "secondary acetate" dissolved in acetone. This should be understood to mean the "cellulose-2.5-acetate". The number "2.5" means the average number of acetyl groups per anhydroglucose unit. For the manufacture of fibers and cigarette filter tow, a degree of polymerization (DP) of 300 is required for the cellulose-2,5-acetate (see page 447, table 15). This should be able to be spun from an acetone solution, the viscosity of which at a concentration of cellulose 2,5-acetate of 20 to 30% and at a temperature of 45 to 55 ° C between 300 and 500 Pa.s (probably meant: .... between 30 and 50 Pa.s ...). Filaments obtained with this have the following physical properties: tensile strength (cN / dtex) 1.0 to 1.5, elongation (%) 25 to 30, density (g / cm 3 ) 1.33, melting point (° C.) 225 to 250 and, as already stated, a degree of polymerization of 300.

WO 94/06954, welches zum Stand der Technik gemäß Artikel 54(3) EPÜ gehört, offenbart ein Verfahren zum Verspinnen einer Lösung in Aceton von Celluloseacetat mit einer intrinsischen Viskosität von vorzugsweise 1,35 (gleich einer DP von 196), oder mehr, und einem Acetylgehalt von 39,5 Gew.-% (kommt überein mit einem Substitutionsgrad (DS) von 2,45). Die Filamente haben einen Titer von bis zu 1,56 dtex (1,4 denier), und enthälten ein feinteiliges Pigment (TiO2) in Mengen weniger als 0,94 Gew.-%.WO 94/06954, which belongs to the prior art according to Article 54 (3) EPC, discloses a method for spinning a solution in acetone of cellulose acetate with an intrinsic viscosity of preferably 1.35 (equal to a DP of 196) or more, and an acetyl content of 39.5% by weight (corresponds to a degree of substitution (DS) of 2.45). The filaments have a titer of up to 1.56 dtex (1.4 denier) and contain a finely divided pigment (TiO 2 ) in amounts of less than 0.94% by weight.

Eine zusammenschauende Betrachtung des Standes der Technik zeigt, daß im Zusammenhang mit Aceton als Lösungsmittel einer Spinnlösung von Cellulose-2,5-Acetat ein hoher Polymerisatonsgrad von 300 mit der Folge verlangt wird, daß die Spinnlösung nur eine niedrige Konzentration von etwa 20 bis 30% an Cellulose-2,5-Acetat aufweist. Bei einem Ausgangsmaterial dieses Polymerisationsgrades kann seine Konzentration in Aceton zur Herstellung einer Spinnlösung nicht weiter angehoben werden, weil damit zwangsläufig ein so starker Anstieg der Viskosität der Spinnlösung verbunden ist, daß diese mit üblichen Spinnvorrichtungen nicht mehr versponnen werden kann (beispielsweise bei 40 bis 50%). Eine merklich angehobene Konzentration würde den Vorteil bieten, daß der Gehalt an Aceton in der Spinnlösung drastisch reduziert werden könnte mit der Folge einer erheblichen Energieeinsparung beim Umlauf und der Rückgewinnung des Acetons.An overall view of the prior art shows that in Connection with acetone as the solvent of a spinning solution of cellulose-2,5-acetate a high degree of polymerization of 300 is required, with the result that the spinning solution only has a low concentration of about 20 to 30% Has cellulose-2.5 acetate. With a starting material of this degree of polymerization can its concentration in acetone to produce a Spinning solution should not be raised further because it is inevitable sharp increase in the viscosity of the spinning solution is associated with that of usual Spinning devices can no longer be spun (for example at 40 to 50%). A noticeably increased concentration would have the advantage offer that the content of acetone in the spinning solution can be drastically reduced could result in significant energy savings in circulation and recovery of acetone.

Der Erfindung liegt somit die Aufgabe zugrunde, Filamente auf der Basis eines in Aceton löslichen Celluloseacetats sowie eine für deren Herstellung besonders geeignete Spinnlösung vorzuschlagen, die die oben geschilderten Nachteile des Standes der Technik, insbesondere die mangelhafte Wirtschaftlichkeit, beheben, ohne daß die Eigenschaften der Filamente, insbesondere die Zugfestigkeit sowie die Dehnung, im Vergleich zu bekannten Erzeugnissen beeinträchtigt werden. The invention is therefore based on the object of filaments on the basis of a cellulose acetate soluble in acetone and one especially for its production propose suitable spinning solution, which has the disadvantages described above the state of the art, especially the poor economy, fix without affecting the properties of the filaments, especially the tensile strength as well as the stretch, compared to known products become.

Die obige Aufgabe wird durch Filamente auf der Basis eines in Aceton löslichen Celluloseacetats gelöst, das dadurch gekennzeichnet ist, daß der Polymerisationsgrad (DP) des Celluloseacetats zwischen 110 und 210 liegt. Besonders bevorzugt wird der Bereich des Polymerisationsgrades zwischen 150 und 180 und insbesondere zwischen 160 und 180.The above task is accomplished by filaments based on a soluble in acetone Dissolved cellulose acetate, which is characterized in that the degree of polymerization (DP) of the cellulose acetate is between 110 and 210. Especially the range of the degree of polymerization is preferred between 150 and 180 and especially between 160 and 180.

Damit das erwähnte Celluloseacetat in Aceton löslich ist, wird sein Substitutionsgrad (DS) vorzugsweise zwischen 2,2 und 2,7 eingestellt. Besonders bevorzugt ist es, wenn der Substitutionsgrad (DS) zwischen 2,4 und 2,6 und ganz besonders bevorzugt zwischen 2,4 und 2,5 liegt.So that the cellulose acetate mentioned is soluble in acetone, its degree of substitution (DS) is preferably set between 2.2 and 2.7. Especially it is preferred if the degree of substitution (DS) is between 2.4 and 2.6 and most preferably between 2.4 and 2.5.

Wenn nachfolgend von einem "Cellulose-2,5-Acetat" gesprochen wird, dann soll dieser Begriff abstrakt verstanden werden. Das bedeutet, daß der Substitutionsgrad von 2,5 mehr oder weniger weit unter- bzw. überschritten werden kann, wobei lediglich die Forderung einzuhalten ist, daß ein derartiges Cellulose-2,5-Acetat bei Raumtemperatur (etwa 20°C) in Aceton löslich ist. Auf jeden Fall soll die Zahl "2,5" in der chemischen Bezeichnung "Cellulose-2,5-Acetat" die zuvor mit dem bevorzugten Substitutionsgrad bezeichneten Celluloseacetate einbeziehen.If the term "cellulose-2.5-acetate" is used below, then this term should be understood abstractly. That means the degree of substitution of 2.5 more or less far below or exceeded can, with only the requirement being met that such a cellulose-2,5-acetate is soluble in acetone at room temperature (about 20 ° C). In any Fall is the number "2.5" in the chemical name "Cellulose-2,5-Acetate" cellulose acetates previously designated with the preferred degree of substitution include.

Der Liter der erfindungsgemäßen Filamente ist nicht kritisch. Vorzugsweise liegt er zwischen etwa 1 und 14 dtex, insbesondere zwischen etwa 1,5 bis 9 dtex. Es handelt sich um die Feinheitsbezeichnung für Filamente, d.h. eine Gewichtsangabe pro Länge, deren Einheit das dtex ist.The liter of filaments according to the invention is not critical. Preferably lies he between about 1 and 14 dtex, in particular between about 1.5 to 9 dtex. It is the fineness designation for filaments, i.e. a weight per length, the unit of which is the dtex.

Es werden die Parameter der erfindungsgemäßen Filamente so eingestellt, daß deren Zugfestigkeit zwischen 0,9 und 1,2 cN/dtex, insbesondere zwischen 1,0 und 1,2 cN/dtex, sowie die Dehnung zwischen 10 und 30%, insbesondere zwischen 15 und 25%, liegt. Damit genügen sie den Anforderungen, die an die bekannten Filamente dieser Art gestellt werden, um sie für die nachfolgend bezeichneten Anwendungsgebiete geeignet zu machen.The parameters of the filaments according to the invention are set in such a way that that their tensile strength between 0.9 and 1.2 cN / dtex, in particular between 1.0 and 1.2 cN / dtex, and the elongation between 10 and 30%, in particular between 15 and 25%. So they are enough the demands placed on the known filaments of this type, to make them suitable for the areas of application described below.

Es hat sich gezeigt, daß die den Kern der Erfindung bildenden und in Aceton löslichen Cellulose-2,5-Acetate geeignet sind, in eine optische isotrope Spinnlösung zur Herstellung von Filamenten überführt zu werden, die dieses Cellulose-2,5-Acetat in Aceton gelöst sowie gegebenenfalls weitere Additive enthält. Erfindungsgemäß ist diese optisch isotrope Spinnlösung dadurch gekennzeichnet, daß die Konzentration des Cellulose-2,5-Acetats in der Spinnlösung 35 bis 47 Masse-% beträgt und der Polymerisationsgrad (DP) des Cellulose-2,5-Acetats zwischen 110 und 210 liegt. Hierbei wird es bevorzugt, daß das Cellulose-2,5-Acetat die vorstehend bereits im Zusammenhang mit der Beschreibung der Filamente genannten Polymerisations- und Substitutionsgrade aufweist.It has been shown that the core of the invention and in acetone soluble cellulose-2,5-acetates are suitable in an optical isotropic spinning solution to be transferred to the manufacture of filaments containing this cellulose-2,5-acetate dissolved in acetone and optionally contains other additives. According to the invention this optically isotropic spinning solution is characterized by that the concentration of cellulose-2,5-acetate in the spinning solution 35 to 47 mass% and the degree of polymerization (DP) of the cellulose-2,5-acetate is between 110 and 210. It is preferred here that the cellulose-2,5-acetate described above in connection with the Description of the filaments called degrees of polymerization and substitution having.

Im Hinblick auf die optimale Konzentration des Cellulose-2,5-Acetats in der erfindungsgemäßen optisch isotropen Spinnlösung ist es von besonderem Vorteil, wenn dessen Konzentration (c) in der Spinnlösung höchstens 8 Masse-% und insbesondere höchstens 6 Masse-% unterhalb der kritischen Konzentration (c*), gemessen bei Raumtemperatur (etwa 20°C), liegt. Wird diese kritische Konzentration an Cellulose-2,5-Acetat zu höheren Konzentrationen der Spinnlösung ohne Einwirkung äußerer Kräfte, wie Scherkräfte, überschritten (c > c*), dann wird die Spinnlösung vom isotropen in den anisotropen Zustand überführt.With regard to the optimal concentration of the cellulose-2,5-acetate in the invention optically isotropic spinning solution it is of particular advantage if its concentration (c) in the spinning solution is at most 8% by mass and in particular at most 6% by mass below the critical concentration (c *), measured at room temperature (approx. 20 ° C). Will this be critical Concentration of cellulose-2,5-acetate at higher concentrations of the spinning solution exceeded without the influence of external forces, such as shear forces (c> c *), then the spinning solution is converted from the isotropic to the anisotropic state.

Um die erfindungsgemäße optisch isotrope Spinnlösung weiter zu verbessern, können ihr verschiedene Additive einverleibt werden, wie Pigmente und Wasser. Vorzugsweise enthält die erfindungsgemäße optisch isotrope Spinnlösung bis zu 6 Masse-% und insbesondere 2 bis 4 Masse-% Wasser. Mit der Einverleibung von Wasser ist der Vorteil verbunden, daß die Viskosität der Spinnlösung mit der Folge einer verbesserten Verspinnbarkeit herabgesetzt wird.In order to further improve the optically isotropic spinning solution according to the invention, various additives can be incorporated, such as pigments and water. The optically isotropic spinning solution according to the invention preferably contains up to 6% by mass and in particular 2 to 4% by mass of water. With the incorporation of water has the advantage that the viscosity of the Spinning solution reduced with the consequence of an improved spinnability becomes.

Wird die erfindungsgemäße optisch isotrope Spinnlösung zur Herstellung von Filamenten eingesetzt, die für ein (Zigaretten)filtertow zur Herstellung von Zigarettenfiltern verwendet werden, dann enthält die Spinnlösung vorzugsweise ein feinteiliges Pigment, insbesondere ein Weißpigment, wie vorzugsweise Titandioxid. Dabei liegt die Teilchengröße zweckmäßigerweise in dem Bereich von etwa 0,3 µm bis 0,5 µm. Die Menge an feinteiligem Pigment in der Spinnlösung beträgt vorzugsweise 0,4 bis 0,8 Masse-%, bezogen auf den Anteil der Spinnlösung an Cellulose-2,5-Acetat. Ganz besonders bevorzugt wird der massenprozentuale Bereich von etwa 0,4 bis 0,6. If the optically isotropic spinning solution according to the invention for the production of Filaments used for a (cigarette) filtertow for the manufacture of cigarette filters are used, then the spinning solution preferably contains one finely divided pigment, in particular a white pigment, such as preferably titanium dioxide. The particle size is expediently in the range of about 0.3 µm to 0.5 µm. The amount of fine pigment in the spinning solution is preferably 0.4 to 0.8 mass%, based on the proportion of Spinning solution on cellulose 2,5-acetate. The percentage by mass is very particularly preferred Range from about 0.4 to 0.6.

Die mit der Erfindung erzielbaren Vorteile lassen sich wie folgt beschreiben: In der Spinnerei läßt sich eine optisch isotrope acetonische Spinnlösung mit einem wesentlich höheren Gehalt an Cellulose-2,5-Acetat herstellen und verspinnen, insbesondere nach dem üblichen Trockenspinnen. Bei der Herstellung von z.B. (Zigaretten)filtertow muß pro Gewichtseinheit produziertem Filtertow aufgrund der hohen Spinnlösungskonzentration sehr viel weniger Aceton als unter den bisherigen Bedingungen zurückgewonnen werden. Auf diese Weise lassen sich, bei z.B. gleicher Filtertow-Produktion, die mit der Rückgewinnung des Acetons verbundenen Kosten merklich veringern. Somit kann in der Spinnerei anhand der erfindungsgemäßen Spinnlösung bei gleicher Viskosität eine Spinnlösung sehr viel höherer Konzentration als bisher hergestellt und verarbeitet werden.The advantages achievable with the invention can be described as follows: In The spinning mill can use an optically isotropic acetone spinning solution with a produce and spin a much higher content of cellulose-2,5-acetate, especially after the usual dry spinning. In the preparation of from e.g. (Cigarettes) filtertow must be produced per unit of filtertow due to the high concentration of spinning solution much less acetone than can be recovered under the previous conditions. In this way can be, e.g. same filter tow production that with the recovery of the acetone associated costs markedly reduce. Thus, in the spinning mill based on the spinning solution according to the invention with the same viscosity Spinning solution produced and processed in a much higher concentration than before become.

Die oben angesprochenen Vorteile werden demzufolge mit einer optisch isotropen acetonischen Spinnlösung hoher Konzentration an Cellulose-2,5-Acetat erzielt. Die Anisotropie bzw. Isotropie kann durch Augenschein festgestellt werden. Eine anisotrope Phase sieht trüb und/oder "perlmuttartig" aus, während die isotrope Phase stets klar ist. Auch kann der jeweilige isotrope bzw. anisotrope Zustand einer Spinnlösung mikroskopisch mit gekreuzten Nicols festgestellt werden. Wenn beispielsweise eine Probe einer anisotropen Spinnlösung zwischen Objektträger und Deckglas eines Mikroskops nach dem Niederdrücken des Deckglases zwischen gekreuzten Nicols beobachtet wird, ist mindestens ein Teil der Lösung lichtdurchlässig. Hierbei spielt auch die Temperatur eine Rolle; wenn die Temperatur einer anisotropen Celluloseacetatlösung von anfänglich Raumtemperatur gesteigert wird, dann kann die anisotrope Phase allmählich in die isotrope Phase übergehen. Wird die Temperatur weiter erhöht, wandelt sich die gesamte Spinnlösung in ein isotropes System um. Die Temperaturbereiche, bei denen diese Übergänge stattfinden, variieren je nach Art des Cellulosederivats, dessen Konzentration in der Spinnlösung und dessen Substitutionsgrad.The advantages mentioned above are accordingly with an optically isotropic acetone spinning solution high concentration of cellulose-2,5-acetate achieved. The anisotropy or isotropy can be determined by visual inspection. An anisotropic phase looks cloudy and / or "pearly" while the isotropic phase is always clear. The respective isotropic or anisotropic can also Condition of a spinning solution determined microscopically with crossed Nicols become. For example, if a sample of an anisotropic spinning solution between slide and cover glass of a microscope after pressing down of the coverslip observed between crossed Nicols is at least part of the solution is translucent. The temperature also plays a role here a role; when the temperature of an anisotropic cellulose acetate solution of initially increased room temperature, then the anisotropic phase gradually change to the isotropic phase. If the temperature is increased further, the entire spinning solution is converted into an isotropic system. The temperature ranges, at which these transitions take place vary depending on the type of Cellulose derivative, its concentration in the spinning solution and its Degree of substitution.

Die Verwendungsmöglichkeiten der erfindungsgemäß erhaltenen Filamente sind im Verlgeich zu den bekannten Filamenten dieser Art nicht eingeschränkt. So können sie zur Herstellung von Filtertow (zu einem Band zusammengefaßte Filamentbündel), für Tabakrauchfilter, insbesondere Zigarettenfilter, aber auch beispielsweise zur Herstellung von - textilen - Garnen für Futterstoffe oder von Mischgeweben mit Baumwolle verwendet werden. The possible uses of the filaments obtained according to the invention are not restricted compared to the known filaments of this type. So they can be used to manufacture filter tow (combined into a band Filament bundle), for tobacco smoke filters, especially cigarette filters, but also for example for the production of - textile - yarns for lining materials or of Blended fabrics with cotton can be used.

Technologisch könnte die vorliegende Erfindung wie folgt erklärt werden: Ausgangspunkt ist eine isotrope acetonische Lösung von Cellulose-2,5-Acetat der bezeichneten Art, deren Konzentration bis dicht an den kritischen Konzentrationswert (c*) angehoben werden kann, von dem an eine anisotrope Phase entsteht. Wird eine derartige isotrope Lösung in die Spinndüsenkanäle (Kapillaren) eingeführt, dann bewirken die durch die Strömungskräfte auftretenden Scherkräfte im Spinndüsenkanal, daß sich überwiegend eine Orientierung und damit Anisotropie einstellt. Im Bereich der Kapillare und nach Austritt aus der Kapillare unterscheidet sich die isotrope Phase nicht von einer echten anisotropen Phase. Aus diesem Grund erhält man in beiden Fällen nahezu gleiche Faserfestigkeiten. Verläßt die Spinnlösung den Spinndüsenkanal, dann treten zwei Abläufe in Konkurrenz, einerseits die Relaxation der orientierten Polymerketten und andererseits die Verdampfung des Acetons. Aufgrund der hohen Konzentration, die nur wenig unter der zuvor bereits erwähnten kritischen Konzentration (c*) liegt, ist die Relaxationszeit der orientierten Polymerketten länger als die Zeit, innerhalb derer durch die Verdampfung des Acetons die kritische Konzentration (c*) erreicht wird. Mit anderen Worten ist die Verdampfungsgeschwindigkeit höher als die Relaxationsgeschwindigkeit. Der anisotrope Zustand stellt sich beispielsweise bei einer Konzentration des Cellulose-2,5-acetas von etwa 47 bis 48 Masse-% in der acetonischen Lösung ein, wenn dessen DP-Wert etwa 150 und dessen DS-Wert etwa 2,45 beträgt. Diese Angabe ist nur beispielhaft. Durch eine möglichst schnelle Verdampfung soll demzufolge die acetonische Spinnlösung des Cellulose-2,5-Acetats in einen solchen Konzentrationsbereich überführt werden, in dem das System Anisotropie zeigt. Im Ergebnis überrascht es also, daß erfindungsgemäß eine isotrope Spinnlösung eingesetzt werden kann und mit dieser in höchst wirtschaftlicher Weise Filamente gewonnen werden können, die bisher nur mit anisotropen Spinnlösungen herstellbar waren.Technologically, the present invention could be explained as follows: The starting point is an isotropic acetone solution of cellulose-2,5-acetate the designated species, their concentration close to the critical Concentration value (c *) can be raised, from which anisotropic Phase arises. Such an isotropic solution will enter the spinneret channels (Capillaries) introduced, then cause those caused by the flow forces Shear forces in the spinneret channel that are predominantly an orientation and thus sets anisotropy. In the area of the capillary and after exiting the isotropic phase from the capillary does not differ from a real one anisotropic phase. For this reason, you get almost the same in both cases Fiber strengths. If the spinning solution leaves the spinneret channel, then two processes compete, on the one hand the relaxation of the oriented ones Polymer chains and on the other hand the evaporation of acetone. Due to the high concentration, just a little below the previously mentioned critical Concentration (c *) is the relaxation time of the oriented polymer chains longer than the time within which the vaporization of the acetone the critical concentration (c *) is reached. In other words, it is Evaporation rate higher than the relaxation rate. Of the Anisotropic state arises, for example, at a concentration of cellulose-2,5-acetas from about 47 to 48% by mass in the acetone solution, if its DP value is about 150 and its DS value is about 2.45. This Information is only an example. Through the fastest possible evaporation consequently the acetone spinning solution of the cellulose-2,5-acetate into one such concentration range can be transferred in which the system anisotropy shows. As a result, it is surprising that an isotropic one according to the invention Spinning solution can be used and with this in the most economical way Wise filaments can be obtained that were previously only possible with anisotropic Spinning solutions were producible.

Die Erfindung soll nachfolgend anhand zweier Beispiele noch näher erläutert werden: The invention will be explained in more detail below with the aid of two examples become:

Beispiel 1:Example 1:

Eingesetzt wurde eine Spinnlösung folgender Zusammensetzung: Masse-% Celluloseacetat (DP: 150; DS: 2,45) 43,2 Wasser 3 Aceton 53,8 A spinning solution with the following composition was used: Dimensions-% Cellulose acetate (DP: 150; DS: 2.45) 43.2 water 3rd acetone 53.8

Die Spinnlösung wurde in einer üblichen Trockenspinnanlage versponnen, die eine Düsenplatte mit 125 Düsenkanälen aufwies. Die Düsenkanäle waren im Querschnitt dreieckig. Das Dreieck hatte eine Kantenlänge von 45 µm. Die Düsentemperatur betrug 47°C und der Düsendruck 88 bar. Die Spinngeschwindigkeit betrug 340 m/min bei einem Verstreckungsfaktor von 1,6. In dem sich unter der Spinndüse befindenden Spinnschacht einer Gesamtlänge von 4 m herrschte eine Temperatur von 70°C. Pro Stunde wurden 10 m3 Aceton-Luftgemisch abgesaugt. Die erhaltenen Filamente hatten die folgenden physikalischen Eigenschaften: Titer 3,1 dtex Zugfestigkeit 1,0 cN/dtex Dehnung 19,4% The spinning solution was spun in a conventional dry spinning system which had a nozzle plate with 125 nozzle channels. The nozzle channels were triangular in cross section. The triangle had an edge length of 45 µm. The nozzle temperature was 47 ° C and the nozzle pressure was 88 bar. The spinning speed was 340 m / min with a draw factor of 1.6. A temperature of 70 ° C prevailed in the spinning shaft with a total length of 4 m located under the spinneret. 10 m 3 of acetone-air mixture were suctioned off per hour. The filaments obtained had the following physical properties: Titer 3.1 dtex tensile strenght 1.0 cN / dtex strain 19.4%

Die mit dem Verfahren nach diesem Beispiel erhaltenen 125 Filamente wurden zu einem Filamentbündeln vereinigt. 80 solcher Filamentbündel wurden zu einem Zigarettenfiltertow (Englisch: cigarette filter tow) zusammengefaßt.The 125 filaments obtained by the method of this example were combined into a filament bundle. 80 such filament bundles became one Cigarette filter tow (English: cigarette filter tow) summarized.

Beispiel 2: Example 2 :

Eingesetzt wurde eine Spinnlösung folgender Zusammensetzung: Masse-% Celluloseacetat (DP: 170; DS: 2,47) 42,1 Wasser 3 Aceton 54,9 A spinning solution with the following composition was used: Dimensions-% Cellulose acetate (DP: 170; DS: 2.47) 42.1 water 3rd acetone 54.9

Die Spinnlösung wurde auf derselben Trockenspinnanlage wie gemäß Beispiel 1 versponnen, allerdings wies die Düsenplatte 240 Düsenkanäle auf. Die Düsenkanäle ware im Querschnitt dreieckig. Das Dreieck hatte eine Kantenlänge von 45 µm. Die Düsentemperatur wurde auf 52°C eingeregelt, und der Düsendruck betrug 80 bar. Die Spinngeschwindigkeit betrug 310 m/min bei einem Verstreckungsfaktor von 1,3. Die Temperatur in dem sich unter der Spinndüse befindenden Spinnschacht mit einer Gesamtlänge von 4 m betrug 70°C. Pro Stunde wurden 10 m3 Aceton-Luftgemisch abgesaugt. Die erhaltenen Filamente hatten die folgenden physikalischen Eigengschaften: Titer 3,6 dtex Zugfestigkeit 1,1 cN/dtex Dehnung 20,5% The spinning solution was spun on the same dry spinning system as in Example 1, but the nozzle plate had 240 nozzle channels. The nozzle channels would be triangular in cross section. The triangle had an edge length of 45 µm. The nozzle temperature was adjusted to 52 ° C and the nozzle pressure was 80 bar. The spinning speed was 310 m / min with a stretching factor of 1.3. The temperature in the spinning shaft located under the spinneret with a total length of 4 m was 70 ° C. 10 m 3 of acetone-air mixture were suctioned off per hour. The filaments obtained had the following physical properties: Titer 3.6 dtex tensile strenght 1.1 cN / dtex strain 20.5%

Claims (17)

  1. Filaments based on a cellulose acetate, which is soluble in acetone, with a degree of polymerisation (DP) between 110 and 210, a tensional strength between 0.9 and 1.2 cN/dtex and an elasticity between 10 and 30%.
  2. Filaments as claimed in claim 1, characterised in that the degree of polymerisation (DP) is between 150 and 180 and particularly between 160 and 180.
  3. Filaments as claimed in claim 1 or 2, characterised in that the degree of substitution (DS) of the cellulose acetate is between 2.2 and 2.7.
  4. Filaments as claimed in claim 3, characterised in that the degree of substitution (DS) of the cellulose acetate is between 2.4 and 2.6 and particularly between 2.4 and 2.5.
  5. Filaments as claimed in one of the preceding claims, characterised in that their denier is between 1 and 14 dtex.
  6. Filaments as claimed in claim 5, characterised in that their denier is between 1.5 and 9 dtex.
  7. Filaments as claimed in at least one of the preceding claims 1 to 6, characterised in that they contain a fine grained pigment, particularly in an amount of 0.1 to 0.8% by mass.
  8. Optically isotropic spinning solution for producing filaments which contains a cellulose acetate, which is dissolved in acetone and has a degree of polymerisation (DP) between 110 and 210 and optionally further additives, characterised in that the concentration of the cellulose acetate in the spinning solution is 35 to 47% by mass.
  9. Spinning solution as claimed in claim 8, characterised in that the degree of polymerisation of the cellulose acetate is between 150 and 180 and particularly between 160 and 180.
  10. Spinning solution as claimed in claim 8 or 9, characterised in that the degree of substitution (DS) of the cellulose acetate is between 2.2 and 2.7.
  11. Spinning solution as claimed in claim 10, characterised in that the degree of substitution (DS) of the cellulose acetate is between 2.4 and 2.6 and particularly between 2.4 and 2.5.
  12. Spinning solution as claimed in at least one of the preceding claims 8 to 11, characterised in that the concentration of the cellulose acetate in the acetone is at most 8% by mass, in particular at most 6% by mass, below the critical concentration (c*), measured at room temperature (about 20°C), whereby if the concentration of cellulose acetate exceeds this value the spinning solution is convened, without the action of external forces, from the isotropic to the anisotropic state.
  13. Spinning solution as claimed in one of the preceding claims 8 to 12, characterised in that it contains up to about 6% by mass, and particularly 2 to 4% by mass, water.
  14. Spinning solution as claimed in at least one of the preceding claims 8 to 13, characterised in that it contains a fine grained pigment.
  15. Spinning solution as claimed in claim 14, characterised in that it contains a white pigment, particularly titanium dioxide, as the fine grained pigment.
  16. Spinning solution as claimed in claim 14 or 15, characterised in that it contains 0.4 to 0.8% by mass fine grained pigment with respect to the cellulose acetate in the spinning solution.
  17. Use of the spinning solution as claimed in at least one of claims 8 to 16 for producing filaments as claimed in at least one of claims 1 to 7 by conventional dry spinning.
EP94100584A 1993-01-26 1994-01-17 Cellulose acetate filaments, an optically isotropic spinning solution therefor and its use for the production of the filaments Expired - Lifetime EP0608744B1 (en)

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RU2085629C1 (en) 1997-07-27
ES2131594T3 (en) 1999-08-01
CN1100478A (en) 1995-03-22
JP2950490B2 (en) 1999-09-20
DE59408019D1 (en) 1999-05-06
CA2113142A1 (en) 1994-07-27
BR9400301A (en) 1994-08-16
EP0608744A1 (en) 1994-08-03
DE4302055C1 (en) 1994-03-24
KR940018496A (en) 1994-08-18
ATE178368T1 (en) 1999-04-15

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