EP1963552A1

EP1963552A1 - Method of producing a dyed formed cellulosic article

Info

Publication number: EP1963552A1
Application number: EP06817492A
Authority: EP
Inventors: Thomas Bechtold; Avinash Pradip Manian
Original assignee: Lenzing AG; Chemiefaser Lenzing AG
Current assignee: Lenzing AG
Priority date: 2005-12-19
Filing date: 2006-12-18
Publication date: 2008-09-03
Anticipated expiration: 2026-12-18
Also published as: CN101389794B; WO2007070904A1; EP1963552B1; EG26561A; ATE462809T1; AT502993A1; DE502006006611D1; AT502993B1; CN101389794A

Abstract

The invention relates to a method of producing a formed cellulosic article dyed using a vat dye, in particular a fibre or a film, comprising the following steps: providing a cellulosic starting material which comprises the vat dye in molecularly disperse form; preparing a formable solution from the cellulosic starting material; forming the solution through a suitable forming tool; precipitating or regenerating the cellulose from the formed solution.

Description

Process for the preparation of a colored cellulosic molding

The invention relates to the production of colored cellulose matrices from vat dyes dyed with vat dyes for the production of colored cellulosic molded bodies. Shaped bodies can be fibers, films or other shapes.

The preparation of dyed in the spinning mass molded articles per se is known in the art. Various technical procedures have been proposed, some of which are also in use:

The most important form of spinning pulp dyeing in the production of cellulosic molded bodies is based on the addition of finely dispersed, insoluble pigments to the spinning mass, which are fixed in the cellulose matrix during subsequent strand formation, and thus have good fastness properties, depending on the type of pigment used. Examples are given below:

For the addition of finely dispersed organic pigments or inorganic pigments to the spinning mass are exemplified: Novacel SA "Colored regenerated ceHulose sponges" FR 1025296 Apr 13, 1953, vide Chemical Abstract No. 52: 3968; Manufactures de produits chimiques du Nord (establissment Kuhlmann) " Coloring viscose fibers "FR 1114803 Apr 17, 1956, vide Chemical AbstractNo. 53: 102 818; Jones, FB "Glossy, spun-dyed threads from aqueous cellulose solutions" DE 1067173 Oct. 15, 1959; Keil, A., Popp, P., and Krause, E. "Process for the production of pigmented regenerated cellulosic fibers" GB 872207 M 5, 1961; Eskridge, B.E. "Manufacture of pigmented viscose rayon" US 3033697 May 8, 1962; Gomm, A.S., Morgan, L.B., and Wood, L. "Process of incorporating aqueous pigment composition in viscose" US 3156574 Nov. 10, 1964; Heinrich, E. "Spin- dyed regenerated cellulose products and process for their manufacture" GB 1046299 Oct 19, 1966; Schoenbach, V., Weisser :, J., and Teige, W. "Pigment dispersions for coloring viscose spinning masses" US Hua, H., and Sakurai, H. "Dope dyeing viscose rayon having a good black luster" JP 47051968 Dec. 27, 1972, vide Chemical Abstract No. 80: 28345.

A disadvantage of the addition of the insoluble dye pigments lies in the difficulty, on the one hand, of achieving the required fine distribution by grinding the pigments and also of maintaining these in the spinning mass. Accordingly, the addition of auxiliaries and additives is also described (Keil, A., Popp, P., and Krause, E. "Process for the production of pigmented regenerated cellulosic fibers" GB 872207 JuI 5, 1961; Eskridge, B. E. "Manufacture of pigmented viscose rayon" US 3033697 May 8, 1962; Gomm, AS, Morgan, LB, and Wood, L. "Process of incorporating aqueous pigment composition in viscose" US 3156574 Nov. 10, 1964; Ono, S., and Igase, T. "Dope dyeing of rayon" JP 54038919 Mar. 24, 1979, vide Chemical abstract no. 91: 40853).

In the preparation of bulk dyed fibers according to the known techniques, recrystallizations and rearrangements of the dye particles or dyes can also be observed (Whitehead, W. "Colored organic derivatives of cellulose and method of making same" US Pat. No. 2,128,338 Aug. 30, 1938).

The described techniques have various disadvantages: Inadequate stability of the pigment in fine distribution and chemical structure leads to difficulties in cellulose regeneration due to deposition of agglomerates, e.g. on spinnerets or color variations in the dyed body. Disturbances in the regeneration bath or precipitation bath, such as, for example, foaming or else the enrichment of auxiliaries required for dispersion stabilization in the precipitation bath, are particularly undesirable (Schoenbach, V., Weissert, J., and Teige, W. "Pigment dispersions for coloring viscose spinning masses" US Pat 3337360 Aug. 22, 1967) Impurities in the precipitating bath would, for example, complicate or completely prevent the solvent regeneration carried out in the NMMO process.The use of insoluble pigments also leads to matting effects and dull colors in the finished moldings, and dichroism and loss of strength may also be observed (Batt, IP, "Process for producing colored pellicular gel structures of regenerated cellulose" US 3005723 Oct 24, 1961; Ruesch, R., and Schmidt, H. "Preparation of dyed filaments and films" US 2043069 Jun. 2, 1936; Eskridge , BE "Manufacture of pigmented viscose rayon" US 3033697 May 8, 19 62. Ciba Ltd. "Process for the preparation of transparent colored articles of regenerated cellulose with the aid of organic dyestuffs of low solubility in water" GB 1128158 Sep 25, 1968).

The cause of dull, dull hues is, in particular, the presence of the color bodies in finely dispersed form, which implicitly causes matting effects due to the limited particle fineness.

The addition of finely dispersed pigments to the spinning solution and the problems resulting therefrom can be circumvented by using soluble dye systems to the dope. The dyes can be pre-dissolved in polar, water-miscible solvents or added directly to the spinning mass (Soc. Pour l'ind., Chim. A BaIe. containing spinning masses "CH 212386 Mar 3, 1941; Phrix-Werke A.-G." Spun-dyed regenerated cellulose "NL 6407087 Jan 18, 1965, vide Chemical Abstract No. 63: 63815; Ciba Ltd." Dyeing of regenerated cellulosic fibers and films "FR 1417575 Nov 12, 1965, vide Chemical Abstract No. 65: 57365; Ciba Ltd." Transparent colored regenerated cellulose "NL 6514672 May 13, 1966, vide Chemical Abstract No. 65: 82924; and Booker, C. "Colored viscose dope" DE 1220964 M 14, 1966; Ciba Ltd. "Process for the preparation of regenerated cellulose with the aid of organic dyestuffs of low solubility in water" GB 1128158 Sep 25, 1968, Riehen, WM, and Reinach, FS "Difficulty soluble organic dye compositions for dyeing transparent, shaped, regenerated cellulose bodies" DE 1806199 Apr 29, 1971, Riehen, WM, and Reinach, FS "Sparingly soluble organic dyestuffs" US 3620788 Nov 16, 1971.).

However, these proposed techniques require far-reaching limitations in the selection of dyes which, for example, must withstand the reductive alkaline conditions of viscose fiber production unscathed, or which must withstand the highly oxidizing environment of a NMMO cellulose solution without chemical change.

In the case of viscose fiber production, the strongly acidic treatment step in the regeneration baths must also be taken into account. In addition, soluble dye systems have the disadvantage of fouling on precipitation baths and of allowing only limited wet fastness in the product since the leaching of the soluble systems is also carried out there (Batt, IP, "Process for producing colored pellicular gel structures of regenerated cellulose" US Pat. No. 3,257,223 Oct. 24, 1961 .).

Particular variants in the production of dyed fibers suggest the addition of sulfur dyes to viscose spuns. Under the reductive alkaline conditions, the dissolution of the sulfur dye, which then has to be returned to its oxidized form (Cassella Farbwerke Mainkur A.-G. "Dyeing of regenerated cellulose in the spinning paste" BE 611323 Dec 29, 1961, vide Chemical Abstract No. 57: 17664).

A further variant recommends the reuse of dyed cellulose textiles with reactive dyestuffs for the production of dyed fibers by the viscose spinning process, the decisive disadvantage being that the dyeings obtained are undefined and not reproducible due to the composition of the raw materials, since some of the dyestuffs are reductively destroyed, while another part remains as a dye (from Eltz, A. "Recycling of dyed cellulosic wastes" EP 0717131 Jun 19, 1996.). The excellent fastness properties of the vat dyes make them particularly interesting for use as pigments for the production of cellulosic molded bodies. An important advantage, but at the same time a processing disadvantage is their insolubility in various media. From the synthesis, vat dyes are obtained as coarse-disperse pigments, for the preparation of which extensive finishing processes such as grinding and processing with adjusting agents, dispersants belong. However, even the gefmishten pigments do not show the color characteristic of the respective vat dye, since the average particle size is still too large and for the color development of a fixed in the cellulose matrix molecular disperse form is needed.

Conventional vat dyeing therefore requires, in the dyeing process, the transfer of the pigment into the alkali-soluble leuco form, which is absorbed by the cellulose fiber and fixed there by reoxidation in the molecular-disperse form.

Various methods have been proposed in the literature for the use of the vat dyes for producing cellulosic shaped bodies, and a distinction can be made between techniques in the field of viscose technology and the so-called amine oxide or lyocell technology.

In the production of viscose fibers, reducing alkaline conditions prevail in the spinning dope, so that here the addition of an already reduced vat dye solution to the dope, the addition of reducible vat dyestuffs or the addition of dyestuff and reducing agent to the dope have been proposed (IG Farbenindustrie A. -G. "The manufacture of dyed artificial masses from regenerated cellulose "GB 465606 May 10, 1937; Kline, HB, and Helm, EB" Manufacture of artificial silk "US 2143883 Jan 17, 1939; Lockhart, GR," Manufacture of rayon "US 1865701 JuI 5, 1932 Batt, IP, "Process for producing colored pellicular gel structures of regenerated cellulose" US 3005723 Oct. 24, 1961). A disadvantage of these working techniques is the enrichment of the precipitation baths with washed-out reducing agents, the costly addition and mixing of dye preparations to secure homogeneous conditions and the dependence of the color shade achieved by the spinning conditions, since the reoxidation in the acidic precipitation bath by no means represents the preferred way of vat dyes oxidation mode.

Other techniques overcome the difficulty of dye reduction in the dope by processing the vat dye dispersion and later reducing and Color development in a filament formation subsequent Verküpungsschritt. Ruesch, R., and Schmidt, H. "Preparation of dyed filaments and films" US 2043069 Jim 2, 1936; IG Farbenindustrie A.-G. "Process for the manufacture of dyed filaments and films" GB 448447 Jim 8, 1936; Maloney, MA "Mass Coloring of Regenerated Cellulose with Vat Dye" DE 1253864 Nov 9, 1967. This process technology thus does not differ in the process balances from the conventional vat dyeing which takes place in textile finishing.

Common to all of these techniques is the need for dye reduction to achieve the final hue of the vat dye. However, the processes also have serious disadvantages which limit the application: the addition of reduced vat dyes led to a stabilization of the spinning dope, altered tire and coagulation behavior adversely affect the production (Ruesch, R., and Schmidt, H. "Preparation of dyed filaments and Films "US 2043069 Jun 2, 1936).

Due to the strong negative reduction potential of these dyes, the reoxidation necessary for color development is difficult to control, which causes Farbtonschwanlcungen (Dosne, H. "Colored cellulose material" US 2041907 May 26, 1936.) In general, many vat dyes can not sufficiently due to their redox potential under the Viskosespinnbedingungen The addition of reducing agent in turn leads to undesirable gel formations in the spinning mass (Lutgerhorst, AG "Spundyed rayon" US 2738252 Mar 13, 1956; Batt, IP, "Process for producing colored pellicular gel structures of regenerated cellulose "US 3005723 Oct. 24, 1961.).

The addition of Küpensäuren or Leukoesterfarbstoffen has already been described, but the disadvantage is the instability of the solutions and the observed tendency to form dye agglomerations (Dosne, H. "Colored cellulose material" US 2041907 May 26, 1936, Lutgerhorst, AG "Spundyed rayon" US 2738252 Mar 13, 1956; IG Farbenindustrie A.-G. "The manufacture of dyed artificial masses from regenerated cellulose" GB 465606 May 10, 1937).

In the production of cellulosic moldings by the amine oxide or Lyo cell method also dye pigments can be added to the dope. A prerequisite for this is an appropriate selection of the suitable pigments, taking into account the strongly oxidizing conditions which are caused by the solvent (N-methyl-N-morpholine-N-oxide - NMMO). As examples, WO 01/11121 (Ruf H., Lenzing AG, 08.03.2000) and WO 99/46434 (Bartsch P., Ruf H., "Method for producing cellulosic molded bodies", Lenzing AG, 10.03.1999), which the Add suitable pigmentary dyes to the NMMO-Spirmmasse. According to WO 99/46434, the vat dyes are also mentioned as colorants which are added as insoluble pigments to the spinning mass, in particular the insolubility of more than 95% required by WO 99/46434 preventing the development of the required vat dye color. The use of a Farbmasterbatcb.es is described, which is to be understood as a color masterbatch according to the prior art, a preparation obtained by mixing colorant with cellulose and optionally NMMO.

The colorant available according to the prior art is then, for example, a pigment or a vat dye, which is mixed into cellulose. However, the cellulose can thus have only a limited fine distribution of the pigment or the vat dye. In the case of vat dyes, therefore, the resulting spin dyeings are by no means corresponding to the results of textile-chemical vat dyeings.

It is an object of the present invention to provide a process for the preparation of a cellulosic dyed cellulosic body which overcomes the disadvantages of the prior art and which achieves uniform dyed products.

This object is achieved by the method according to claim 1. Preferred embodiments of the method according to the invention are specified in the subclaims.

The possibility of incorporating the vat dyes into a cellulosic matrix by means of a dyeing process and to produce dyed fibers from them is not disclosed in the prior art.

The present invention is based on the surprising finding that a cellulosic starting material such as a pulp can serve as a solid matrix for molecularly dispersed vat dye. The molecular disperse distribution of the dye can be effected by coloring the pulp according to the usual methods for the use of vat dyes, eg Ausziehverfahen, continuous process, wherein after completion of the dye, the dye is no longer present as an original pigment with particle sizes in the micrometer range, but molecularly dispersed in the cellulose is embedded. Unexpectedly, this colored cellulose is particularly well suited for incorporation of the dye in molecularly disperse form in spinning masses. The actual spinning masses can be produced by dissolving the cellulose by the viscose process or the amine oxide or lyocell process.

The incorporation of the dye in the molecularly disperse form avoids the problems of pigment addition as well as the difficulty of hue development unsatisfactory in comparable known processes. In contrast to WO 99/46434, a color result is achieved which no longer corresponds to a vat pigment addition to the dope, but which is to be equated as a result of a vat dyeing produced according to the prior art.

The following development steps of the vat dyeing (reduction / oxidation) can be avoided in the inventive process on the filament formation. The presence of the dye in molecularly disperse form achieves high dye yields with high brilliance. In contrast to pigment dyeings, pigments are no longer visible under the microscope. The dyeing result therefore corresponds to a vat dyeing in hue, color depth and fastness properties, but may be based on the treatment of the fibers in strongly swelling alkaline baths, as is customary in dyeing with vat dyes, and also on the dyeing, which is difficult to color, e.g. Winding body, be waived.

In particular, when dyeing the pulp with high dye concentration, e.g. 20% by weight of dye based on the weight of the pulp, the vat dye-containing cellulosic starting material can be processed together with at least one further, optionally also a dye-containing starting material to formable solution.

There is thus a spin dyeing by admixture of a part of dyed with the vat dye cellulose. As a result, particularly advantageous emission balances, based on the dyeing step, are obtained. By preparing the cellulose as a dyed dyestuff matrix, the dyestuff is added to the spinning process without the otherwise existing finish aids, so that an enrichment of additives and their complicated removal can be omitted. In a particularly preferred embodiment, the vat dye-containing cellulosic starting material is fed without further drying of the further processing in the spinning process.

The dyeing of the cellulosic starting material can according to the procedure according to the invention with vat dyes in a depth of 0.1 to 25% (mass of dye to mass cellulosic starting material), preferably from 1 to 20%, particularly preferably from 5 to 10% (each mass of dye to Mass cellulosic starting material).

In the case of exhaust dyeings, the liquor ratio (mass of dyestuff to volume dyebath) can be between 1: 0.8 to 1:50, preferably between 1: 5 to 1:10. The dyeing process may be carried out at temperatures of 20-80 ° C using conventional vat dyeing techniques. Also, continuous dyeing techniques, e.g. using modified screen belt equipment, can be applied.

Particularly advantageous are dyeing processes employing dyeing techniques with dyebath recovery, e.g. Dyeing upstanding bath. By carrying out the dyeing as a relatively high concentration of color, the process-related emissions (wastewater, energy, chemicals) are significantly lower than with conventional vat dyeing processes.

By avoiding the usual alkaline vat dyeing carried out under relatively severe conditions, it is also possible to produce sensitive substrates dyed without impairing the fiber properties with vat dyes.

When dyeing the cellulosic starting material Egal Egal differences can be accepted, since only the dye uptake must be achieved. Because of the subsequent dissolution of the cellulosic starting material and the production of the fiber, an excellent levelness is achieved "automatically" as it were.

It can therefore be used in dyeing the cellulosic starting material with much shorter process times. In addition, it is possible to dispense with the addition of dispersing and leveling auxiliaries in the dyebath. This results in further economic and environmental benefits, as reduced emissions from the dyeing process occur. The cellulosic starting material containing the vat dye can be mixed, depending on the desired color depth, with an optionally undyed cellulosic starting material, the mixing ratio of vat dye-containing starting material to the other starting material (s) being from 0.1: 10 to 10: 0.1, preferably from 1:10 to 10: 1 can be. The mixing ratios depend on the dye content of the presented colored cellulosic starting material and the color depth of the spun-dyed material to be produced.

The cellulosic starting material and / or the at least one further starting material may in particular be selected from the group consisting of pulp, natural and man-made cellulose fibers and piecing material of a process for the production of cellulose fibers.

Thus, instead of using dyed pulps, undyed cellulose fibers can also be dyed with vat dyes and serve as cellulosic matrix. A particularly preferred embodiment uses for this purpose so-called piecing material, which arises when starting a fiber production plant and does not yet meet the quality requirements of the fibers, but is suitable as a cellulose matrix.

A preferred embodiment of the method according to the invention is characterized in that the starting material (s) is / are further processed by means of the viscose process or by means of the amine oxide process to give the shaped body.

The viscose process and the amine oxide process or lyocell process are well known to the person skilled in the art. The amine oxide or lyocell process is described in more detail, for example, in EP 0 356 419 A or in WO 93/19230.

The invention further relates to the use of a cellulosic material which contains a vat dye in molecularly disperse form, as starting material for the production of a cellulosic shaped body.

The invention also relates to a cellulosic molding, in particular a cellulose fiber, which is obtainable by the process according to the invention.

The cellulose molded bodies according to the invention are completely through-dyed with the vat dye because of the process according to the invention. Due to the process according to the invention, moreover, an average particle size of the vat dye in the cellulose matrix of less than 0.1 μm can be achieved. The dye is thus no longer visible under a light microscope ordinary resolution at eg 400-fold magnification.

This is in contrast to Celluloseformkörpem, which can be obtained by adding an insoluble dye pigment to the dope and in which the particle size of the pigments in the fiber in the micrometer range.

Finally, the invention relates to a textile article, e.g. a yarn, a fabric or clothing containing a cellulosic shaped body according to the invention in the form of a fiber.

It turns out that textile articles containing a cellulosic fiber according to the invention have excellent micro- and macroegalities, which is comparable to the level of levelness obtainable in conventional vat dyeing of textiles.

In particular, yarn dyeing by means of vat dyes often proves to be difficult, while using a cellulosic fiber according to the invention yarns can be produced with excellent uniform Farbegalitäten.

In addition, the textile articles according to the invention are completely dyed due to the use of the cellulose fiber according to the invention. Complete staining is difficult to achieve with conventional vat dyeing of textiles.

The present invention is explained in more detail below by means of an exemplary embodiment:

example 1

About 350 g of fiber pulp (Lenzing AG) are dyed by exhaustion with CI Vat Green 5 (Indanthrene Brilliant Green FFB, Dystar, Frankfurt, Germany) for 45 min at 50 ° C. in a liquor ratio of 1:15 in a dyebath which has the following composition : 10 g / L dye, 6.17 g / L NaOH, and 5 g / L Na ₂ S ₂ O ₄ .

During pre-caking, the dye-cake and the residual dyebath containing the pulp are brought to dyeing temperature. After reaching the dyeing temperature, the solution containing the reduced dye and the pre-pulp containing bath mixed and the dyeing process is started. After 45 minutes at dyeing temperature, the dyeing process is terminated. The pulp is thoroughly rinsed and the oxidation step is carried out by air oxidation. Subsequently, the dyed pulp is dried. The dyed cellulose matrix is mixed with undyed pulp in a ratio of 1: 4 and processed into dyed fibers by the amine oxide or lyocell method. It is obtained a 2.5% color, which corresponds in color and fastness (wash fastness, light fastness) to the dyeings produced by conventional methods.

Claims

Claims:

A process for the preparation of a cellulosic dyed cellulosic shaped body, in particular a fiber or a foil, comprising the steps

- Providing a cellulosic starting material containing the vat dye in molecularly dispersed form

- Making a moldable solution of the cellulosic starting material

- Forming the solution by a suitable mold

- precipitating or regenerating the cellulose from the formed solution.

2. The method according to claim 1, characterized in that the cellulosic starting material, the vat dye in a ratio of the mass of the dye to the mass of the cellulosic material of 0.1% to 25%, preferably 1% to 20%, particularly preferably 5% to 10th %, contains.

3. The method according to any one of the preceding claims, characterized in that the vat dye-containing cellulosic starting material is processed together with at least one further, optionally also a dye-containing starting material to formable solution.

4. The method according to claim 3, characterized in that the at least one further starting material is a cellulosic material.

5. Process according to claim 3 or 4, characterized in that the mixing ratio of the vat dye-containing cellulosic starting material to the other starting material (s) is 0.1: 10 to 10: 0.1, preferably 1: 10 to 10: 1 is.

6. The method according to any one of the preceding claims, characterized in that the cellulosic starting material and / or the at least one further starting material from the group consisting of pulp, natural and manmade cellulose fibers and piecing material of a method for producing cellulose fibers is selected.

7. The method according to any one of the preceding claims, characterized in that the or the starting materials by the viscose process or by means of the amine oxide process is further processed to the molding.

8. The method according to any one of the preceding claims, characterized in that the cellulosic starting material containing the vat dye is not subjected to a drying step prior to the preparation of the moldable solution.

9. Use of a cellulosic material which contains a vat dye in molecularly disperse form, as starting material for producing a cellulosic shaped body.

A process for producing a cellulosic starting material for use in a process according to any one of claims 1 to 8, which comprises dyeing a cellulosic material with a vat dye by the exhaustion process or a continuous dyeing process.

11. Cellulosic shaped body obtainable by a process according to one of claims 1 to 8.

12. A cellulosic molding according to claim 11, characterized in that the average particle size of the vat dye in the cellulose matrix is less than 0.1 microns.

13. Textile article, e.g. a yarn, fabric or garment comprising a cellulosic body according to claim 11 or 12 in the form of a fiber.