DE102019104203A1 - Process for the production of colored fiber materials and their use - Google Patents

Abstract

A process is described for the production of colored fiber materials based on m-aramid fibers or fiber blends containing m-aramid fibers subsequently dyed with vat dyes, the use of carriers which are harmful to the environment and health can be dispensed with. This method is characterized in that the m-aramid fibers are subsequently dyed with vat dyes by a) applying vat dyes in an aqueous dispersion containing urea or urea derivatives directly to the m-aramid fibers or fiber blends containing m-aramid fibers and then the vat pigment is fixed on the fiber materials, or b) the vat dyes are converted into the leuco form by adding reducing agents in an alkaline medium, the resulting vat containing urea and / or urea derivatives and the vat with the m-aramid Fibers or the fiber blends containing m-aramid fibers is brought into contact, the vat dyes are oxidatively formed from the leuco form and a fixation of the vat dyes is carried out on the fiber materials. The fiber materials obtained by this process can be used advantageously for the production of clothing and equipment, in particular flame-retardant or fire protection textiles for personal protective clothing, in particular for military, fire brigade and police personnel, work clothing or for use in the contract sector. The particular advantage of the method according to the invention is that it provides colored fiber materials with high color fastness and good color yields without a significant loss of the elastic properties occurring.

Description

The invention relates to a process for the production of colored fiber materials based on m-aramid fibers or fiber blends containing m-aramid fibers which are subsequently dyed with vat dyes, and the use of the colored fiber materials for the production of items of clothing.

In the area of personal protective clothing, aramid fibers are one of the most frequently used types of fiber in terms of quantity, primarily due to their inherently self-extinguishing properties. Known m-aramids are, for example, Nomex ^® from. DuPont de Nemours, Teijinconex ^® from. Teijin or Yantai Newstar ^® from. Yantai. The dyeing of textiles made of m-aramid fibers and fiber blends containing them is a major problem. In principle, m-aramid fibers can be dyed with selected cationic dyes under high temperature conditions using the exhaust or continuous process (see e.g. Fiebig D., Küster B., Herlinger H .: "A possibility for continuous coloring of poly-m-phenylene isophthalamide", textilpraxis intern. 49 (1994), 260-262, 265, 266 or die DE 10 2009 039 606 B3 ). The prerequisite is that relatively large amounts of carriers (dye accelerators) have to be added to the dye bath. This is mainly due to the fact that the glass transition temperatures (T _g ) of m-aramids are very high. For poly-m-phenylene isophthalamide as a typical m-aramid, the T _g is approx. 270 ° C. In polymers, the glass transition temperature is the temperature above which the macromolecules in the amorphous areas acquire a certain mobility. In terms of dyeing technology, the T _g is relevant to the extent that dye molecules above the T _{g are given} the opportunity to diffuse into the interior of the fiber due to the chain mobility that occurs. The effect of a carrier is to promote this chain mobility so that, depending on the carrier concentration, dyeing is possible at a significantly lower temperature. According to Roberts and Solanki (J. Soc. Dyers Col. 95 (1979), 226 and ibid. 427), the action of a carrier leads to plasticization of the polymer with a simultaneous lowering of the T _g . A similar effect occurs when solvents are added to the dyebaths that are relevant for spinning the m-aramids, for example dimethylacetamide (see e.g. Moore RF, Weigmann H.-J .: “Dyeability of Nomex Aramid Yarn”, Textile Res. J. 56 (1986), 254-260 ), 1,3-dimethylimidazolidinone or selected ionic liquids. However, such admixtures are forbidden for practical use in dyeing.

Carrier dyeing

Usually, m-aramids are dyed at about 120 ° C., i.e. under HT (high temperature) conditions, in a weakly acidic medium with the addition of considerable amounts (30-90 g / l) of carrier. Without the addition of a carrier in the dye liquor, the cationic dyeings carried out in production today according to the state of the art result in weakly colored textile samples that are only superficially colored. The carriers used are usually aromatics. Frequently used are e.g. Benzyl alcohol, acetophenone or 2-phenoxyethanol. Other compounds that can develop the effect of a carrier are 1,2,4-trichlorobenzene, 1-methylnaphthalene, o-dichlorobenzene or n-butylbenzoate (Roberts G. and Solanki R. in J. Soc. Dye. Col. 95 ( 1979), 226 and ibid. 427). Due to their generally low solubility in water, the presence of emulsifying auxiliaries is necessary so that these are emulsified in the aqueous dye liquors.

All available carriers are hazardous to health and the environment. In the practice of carrier dyeing, extensive and expensive measures are therefore required to minimize emissions from carriers into the air and wastewater. At the same time, this critical emission behavior means a significant restriction with regard to the available dyeing processes. Coloring is usually done in closed, high-temperature and overpressure-suitable apparatus. Coloring in quasi-open systems such as in a damper or on a stenter frame is practically impossible. Another disadvantage is that the lightfastness of the aramid samples dyed with cationic dyes and carriers is poor, which is insufficient for many applications. Disperse dyes which are dyed according to current formulations for dispersion dyeing on aramid with added carrier show a relatively poor color yield. At the same time, the light fastness properties are generally poor, even when using highly lightfast disperse dyestuffs (see F. Gähr, S. Berndt in TextilPlus 2018, issue 5/6, pp. 16-19 ).

Process of fiber pretreatment

Further alternatives described according to the prior art aim at the pretreatment of the fiber by means of suitable measures that trigger an increased affinity of the fiber surface for various dyes. In DE 43 35 717 A1 is the treatment of aromatic polyamides in an alcoholic Solution of a hydrolyzable alkoxysilane such as (3-triethoxysilylpropyl) octadecyl-dimethyl-ammonium chloride described. The finished, cationized fiber material can then be dyed reactively. Disadvantages of the process are, on the one hand, the solvent-based process management, and, on the other hand, poor color fastness is obtained due to the cationization and the marginal colorations produced thereby. In Melliand Textilber. 4/2018, 159-161 describes the possibility of equipping aramids with polyvinylamine to improve UV resistance and colorability. The color fastness properties that can be achieved with anionic dyes, in particular the light fastness and rubbing fastness, are, however, inadequate even with this method because of the edge coloring. Physical pretreatment measures, such as fiber activation by plasmas, are also generally of interest, but here too the color fastness properties are extremely unsatisfactory. The effect of the plasma remains limited to the fiber surface (approx. 4-10 nm), so that edge colorations are the rule and consequently poor fastness properties almost inevitably result.

Vat and vat pigment coloring

As an alternative to dyeing with cationic (basic) dyes, approaches are described in the prior art to dye m-aramids with vat dyes. Vat dyes are usually used for cellulosic fiber materials, specifically when high color fastness properties are required. The indanthrene dyes developed by BASF Ludwigshafen, which have excellent lightfastness, are known here. The general process principles on which the dyeing of cotton with vat dyes is based are known to the person skilled in the art. The first step of the dyeing process is the vatting of the water-insoluble dye by means of suitable reducing agents in an alkaline medium. The result is the water-soluble, molecularly present and generally yellowish leuco form. The alkaline leuco form molecules have a particularly high affinity for cellulose, so that they are easily absorbed by the cellulose fiber. After absorption, oxidation takes place with atmospheric oxygen (or other oxidizing agents), whereby the water-insoluble dye regresses and is firmly anchored in the cellulose pore system. The last step in the coloring process is an after-soaping process, during which dyes adhering to the surface are removed and the brilliance of the coloring is increased. Depending on the redox potential, the constitution of the dye and the temperature-dependent affinity of the dye to be considered for the fiber, different variants of the standard process have developed. In addition to this standard process, there are also some special vat dyeing procedures that can be of particular interest for the coloring of synthetic fibers. In the WO 96/04420 A1 describes the dyeing of textiles made of synthetic fibers with vat dyes in an alkaline medium. The dyeing of a Nomex ^® fabric takes place at 135 ° C without a carrier. For this, however, very large amounts of alkali and reducing agent have to be used, which in turn leads to extremely severe fiber damage.

In TextilPlus 2018, issue 5/6, pp. 16-19, Gähr and Berndt describe a Leuko-HT process that is based on the process of vat dyeing of cotton described above. However, for dyeing articles made of 100% m-aramid and e.g. Nomex ^® Comfort (93% m-aramid, 5% p-aramid and 2% antistatic fibers), analogous to dyeing with cationic dyes, HT conditions (115 ° C) as well as the addition of a carrier necessary. The resulting textile samples are deep in color when a carrier is added. Without the addition of a carrier, the lightfastness is, depending on the dye, at a significantly higher level than with cationically colored aramids. The addition of a carrier in the dyebath generally leads, analogously to the cationic dyeing, to significantly improved color yields; at the same time, however, the carrier results in a loss of light fastness by 1-2 points.

In the US 6,942,706 B2 a process based on vat acids is described for the dyeing of synthetic fibers, which is said to be suitable for providing high color depths and wash fastness. The fibers are treated with leukocyte acids under suitable conditions. The decisive factor is maintaining a weakly acidic reducing environment, with special reducing agent admixtures paired with controlled additions of citric acid. As Gähr and Berndt (see above) found when comparing the various methods, the color depths determined on the basis of the K / S values are always lower when the carrier is omitted for the vat acid method than in the Leuko-HT method. Furthermore, in the presence of a carrier, the lightfastness grades also deteriorate significantly here.

In the DE 10 2015 114 501 A1 a method is described which works without the vatting step. The vat pigments are applied using a pigment padding process and fixed with hot air or superheated steam. The coloring takes place exclusively in the pigment form without the addition of a reducing agent and alkali. Very good light fastness properties are obtained. In order to achieve good color yields, the addition of a carrier (benzyl alcohol) is necessary even after this process.

Prior Art Problems

• - ein rascher Wechsel auf den vom Kunden gewünschten Farbton ist erschwert,
• - viele Farbtöne für die Dichromie- oder Trichromiefärbungen die Voraussetzung sind, sind nicht einstellbar und daher nicht realisierbar,
• - es müssen ständig spinngefärbte Fasern in größerer Menge vorgehalten werden, um bei Bedarf, d.h. Auftragseingang, rasch reagieren zu können,
• - bei Fasermischungen müssen die Farbtöne beider Fasern meist entsprechend angepasst sein,

spinngefärbte Fasern aus m-Aramid liegen kostenmäßig auf einem etwa doppelt so hohen Preisniveau wie ungefärbte Fasern.All of the described methods of subsequent dyeing of m-aramid fibers, be it discontinuously or continuously, have the disadvantages, firstly, of inadequate color absorption, provided no carrier is used, and secondly that the dyed textiles have insufficient color fastness, especially poor light fastness. This is the reason why the majority of dyed aramid fibers are still spun-dyed on the market today (> 90%), with all the disadvantages that are well known of spun-dyed fibers:

• - a quick change to the color required by the customer is difficult,
• - many color tones for which dichromatic or trichromatic colors are required, cannot be set and therefore cannot be implemented,
• - Spun-dyed fibers have to be kept in large quantities at all times in order to be able to react quickly when required, i.e. incoming orders,
• - In the case of fiber blends, the color tones of both fibers must usually be adjusted accordingly

Spun-dyed fibers made from m-aramid are about twice as expensive as undyed fibers.

The subject of the subsequent coloring of m-aramid-containing fiber materials, namely with the necessary high fastness properties and without the use of carriers, therefore enjoys high priority in the textile industry. The use of carriers poses a major problem from an ecological point of view. These emit a strong odor nuisance at the workplace and they require complex measures with regard to minimizing emissions and separate disposal of residual fleets containing carriers.

Another problem with carrier dyeing arises when dyeing fiber blends made of m-aramid with other flame-retardant fibers, such as, for example, viscose FR, Modal FR or Lyocell FR (FR = flame retardant). The flame-retardant cellulose fibers are often mixed with the m-aramid fibers for reasons of comfort. Subsequent coloring is done with cationic dyes. As a rule, they contain additives based on phosphorus-sulfur compounds for the purpose of flame retardancy (see e.g. R. Wolf "Flame Retardant Viscose Rayon Containing a Pyrophosphate" in Ind. Eng. Chem. Res. Dev. 20: 413-420 (1981) ). The corresponding additives, which are contained up to a content of 20% by weight based on the cellulose fiber, are successively extracted under the HT conditions of the carrier dye necessary for the aramid content. This leads to a significant loss in the flame resistance of the fiber blend as a whole. For this reason, too, there is a great desire in practice to be able to access a method that makes the addition of a carrier superfluous.

A further disadvantage of dyeing runs with carriers carried out according to the prior art is that such dyeings lead to unsatisfactory textile properties in knitted fabrics. Compared to woven fabrics, knitted goods are characterized by a significantly higher elasticity and, especially in the case of clothing textiles, also by a lighter and usually softer handle. Knitted goods, which include knitted goods and knitted goods, are significantly more sensitive to mechanical stress than woven fabrics when subjected to thermal or hydrothermal treatment. They lose their elasticity more quickly, which is expressed in the tensile / elongation test with regard to the hysteresis in a reduced rebound force and an increased permanent elongation. These advantageous properties are negatively influenced in the course of coloring under HT conditions when the aromatic carriers mentioned are added.

A particular disadvantage of carrier dyeing is that the dyed m-aramid fibers still contain residues of carriers that are difficult to remove by simple washing processes at the end of the finishing chain. This means that in the dyed aramid-containing fibers, yarns or textiles when they are delivered to the customer, carriers are often still present, at least in traces (see example 1).

Object of the invention

The object of the present invention is therefore to provide industrial practice with a process for the subsequent coloring of m-aramid fibers and fiber blends containing m-aramid, which process dispenses with the use of carriers that are harmful to the environment and health and nevertheless good color yields and Provides fastnesses. At the same time, the use of suitable spinning solvents for m-aramids, which act as plasticizers with a carrier-like effect, must be ruled out.

It is a further object of the invention to achieve dyeings in color shades which, according to the prior art, are usually achieved on m-aramid only via di- or trichromats, with high fastness properties and without using a carrier.

According to a further object of the invention, the dyeing process according to the invention should also be suitable for lightfast dyeing of m-aramid-containing knitted fabrics without a significant loss of the elastic properties occurring.

According to a further object, the method according to the invention should be able to be carried out on conventional dyeing apparatus and machines in the textile industry. In particular, it should allow working in quasi-open dyeing machines.

solution

According to the invention, the above objects are achieved by a process for the production of colored fiber materials based on m-aramid fibers or fiber blends containing m-aramid fibers subsequently colored with vat dyes, which is characterized in that the m-aramid fibers are subsequently dyed with vat dyes are colored by a) vat dyes in an aqueous dispersion containing urea or urea derivatives are applied directly to the m-aramid fibers or the fiber blends containing m-aramid fibers and then a fixation of the vat pigment is carried out on the fiber materials, or b) the vat dyes are converted into the leuco form by adding reducing agents in an alkaline medium, the resulting vat containing urea and / or urea derivatives and the vat being brought into contact with the m-aramid fibers or the fiber mixtures containing m-aramid fibers Vat dyes oxidatively from the Le ukoform are formed and a fixation of the vat dyes is carried out on the fiber materials.

• - die Geruchsneutralität,
• - eine hervorragende Wasserlöslichkeit, die zum einen den Einsatz von Emulgierhilfsmitteln erübrigt und zum zweiten für eine leichte Auswaschbarkeit des Harnstoffs am Ende der Färbung sorgt,
• - seine hydrotropen Eigenschaften, die für die Löslichkeit der handelsüblichen Küpenfarbstoffpigmente förderlich sind und zur Beschleunigung der Farbstoffdiffusion in die m-Aramidfasern beitragen,
• - seine hygroskopischen Eigenschaften, die insbesondere bei Farbstofffixierungsprozessen in einem Dämpfer oder auf einem Spannrahmen zum Tragen kommen.
• - Die Färbung der m-Aramidfasern kann nach Verfahren der für Küpenfarbstoffe üblichen Färbepraxis durchgeführt werden.

The above objects are thus achieved according to the invention in that the dyeing with vat dyes is carried out with the simultaneous action of urea and / or urea derivatives. It has surprisingly been found that urea has a positive effect on the dyeing speed and the depth of color without impairing the color fastness. Urea is a substance that is good for the environment and the body. Other benefits of urea are:

• - the odorlessness,
• - excellent water solubility, which on the one hand makes the use of emulsifying aids unnecessary and on the other hand ensures that the urea can be easily washed out at the end of the dyeing process,
• - its hydrotropic properties, which are beneficial for the solubility of the commercially available vat dye pigments and contribute to the acceleration of the dye diffusion into the m-aramid fibers,
• - Its hygroscopic properties, which are particularly useful in dye fixation processes in a steamer or on a tenter frame.
• - The dyeing of the m-aramid fibers can be carried out according to the usual dyeing practice for vat dyes.

Water-soluble compounds such as biuret or O-alkylureas are preferred as urea derivatives.

The invention can experience a wide variety of advantageous developments, which will first be discussed below: When carrying out the method according to the invention, the type of fibers that are to be colored subsequently is not critical. It is preferred that the m-aramid fibers and the fiber blends containing m-aramid fibers are based on fiber flocks, fiber tows, slivers, rovings, yarns, woven fabrics, knitted fabrics, in particular knitted and knitted fabrics, braids or fleece. It is particularly preferred if the fiber blends containing m-aramid contain further fibers which can be dyed with vat dyes, in particular in the form of viscose, modal, lyocell, polyamide and / or polypropylene fibers and / or wool. The further fibers mentioned experience an advantageous design in that they are inherently flame-retardant and have an LOI according to ASTM D2863 of at least 23, in particular of at least 27. The further fibers are advantageously in the form of cellulose, regenerated cellulose, aliphatic, aliphatic-aromatic and aromatic polyamide and / or polyester fibers. When used of further fibers, it is advantageous if these make up about 1 to 75% by weight, in particular about 5 to 60% by weight, based on the total weight of the fiber mixtures.

The particle size of the vat dyes in process step a) is not critical. However, it is expedient if, in step a), these have a particle size of about 0.1 to 3 μm, in particular about 0.2 to 0.8 μm.

The person skilled in the art is not restricted in the choice of vat dyes. It is considered preferred that the vat dyes are used in the form of indigo, indigo derivative, anthraquinone, anthraquinone oxazole, anthraquinone carbazole, indanthrone, flavanthrone, benzanthrone or pyranthrone dyes or sulfur dyes. Specifically preferred vat dyes are listed as C.I. Vat Green 1, Vat Green 13, C.I. Vat Red 32, C.I. Vat Red 10, C.I. Vat Blue 4, C.I. Vat Blue 20, C.I. Vat Yellow 28, C.I. Vat Orange 29, C.I. Vat Brown 9, C.I. Vat Black 9 and / or C.I. Sulfur Black 9 was used.

The invention is also not subject to any critical restrictions when applying the aqueous dispersion in step a) and the vat in step b). It is considered preferred that the aqueous dispersion in step a) and the vat in step b) are applied continuously with a padder, pad or doctor blade, or the contacting with the fiber material is carried out in the form of a discontinuous exhaust process. It is also preferred that the aqueous dispersion in step a) and the vat in step b) have about 0.1 to 10 mol / l, in particular 1 to 5 mol / l and particularly preferably 2 to 4 mol / l urea and / or Contain urea derivative.

With regard to the concentration of the vat dyes in the aqueous dispersion after step a) or in the alkaline medium after step b), it is preferred that the vat dyes in the aqueous dispersion of step a) in a concentration of 1.5 to 110 g / l, in particular from 5 to 60 g / l, and in the alkaline medium in step b) in a concentration of 0.05 to 30 g / l, in particular from 0.2 to 20 g / l. An advantageous further development of the method according to the invention consists in that, after the vat dyes have been formed in step b), an after-soaking step is carried out.

After the application or formation of the vat dyes after step a) or step b), it is preferred that the vat dyes are fixed in step a) and step b) as a) dry heat fixation between 140 and 260 ° C., in particular between 170 and 220 ° C, (thermosol process), b) steam setting at a temperature between 100 and 160 ° C, in particular between 110 and 155 ° C, and / or c) exhaust dyeing between 70 and 150 ° C, in particular between 98 and 125 ° C.

In view of the fact that the effects of the invention appear particularly advantageously when there are no carrier materials, it is therefore considered very useful that carrier materials, in particular benzyl alcohol, acetophenone or 2-phenoxyethanol, are largely used when carrying out the method excluded are.

The particular advantage of the process product obtained according to the invention as such is shown in its use. The use for the production of clothing and equipment, in particular flame-retardant or fire-resistant textiles for personal protective clothing, in particular for military, fire brigade and police personnel, work clothing, face masks and protective hoods (balaclava), gloves, underwear (long-arm) applies -shirts, Long-Johns), covers for hot air balloons or for use in the contract sector, are particularly preferred.

• Das erfindungsgemäße Verfahren ist auf vielen gängigen Färbeapparaten und Maschinen der Textilindustrie durchführbar. Hierzu zählen diskontinuierliche Verfahren, die in Form einer Auszieh- oder Stückfärbung unter Anwendung praxisüblicher Flottenverhältnisse durchgeführt werden. Für die Ausziehfärbung kann beispielsweise ein Jigger, eine Haspelkufe oder ein Färbe-Jet eingesetzt werden. Andere Färbeverfahren der Stückfärbung oder der Garnfärbung, wie zum Beispiel das Färben auf dem Baum bzw. auf der Spule, sind besonders vorteilhafte Ausgestaltungen des erfindungsgemäßen Verfahrens. Für das Arbeiten nach dem Ausziehverfahren wird bevorzugt aus der Küpe und unter HT-Bedingungen in geeigneten Überdruck-geeigneten Behältern gefärbt. Der Farbstoff wird in alkalischem Medium durch Reduktionsmittelzugabe zunächst verküpt, dann mit dem Fasermaterial in Kontakt gebracht, und dann fixiert beziehungsweise oxidiert. (Prinzipiell entspricht dieses Verfahren dem Stand der Technik mit dem Unterschied, dass die Färbeflotten Harnstoff anstelle eines Carriers enthalten.) Je nach Dichte des Materials bzw. des Wickelkörpers ist aber auch das Färben mit feinstverteilten Küpenpigmenten möglich. Hierbei wird auf die Verküpung verzichtet.

In accordance with the above preferred embodiments of the invention, the following statements should be understood, which on the one hand relate to further advantageous developments, but are also intended to explain the method according to the invention described in detail above:

• The method according to the invention can be carried out on many common dyeing apparatus and machines in the textile industry. These include discontinuous processes which are carried out in the form of exhaust or piece dyeing using liquor ratios customary in practice. For example, a jigger, a reel runner or a dye jet can be used for exhaust dyeing. Other dyeing methods of piece dyeing or thread dyeing, such as dyeing on the tree or on the bobbin, are particularly advantageous embodiments of the method according to the invention. For working according to the exhaust process, dyeing is preferred from the vat and under HT conditions in suitable containers suitable for overpressure. The dye is first vat in an alkaline medium by adding a reducing agent, then brought into contact with the fiber material and then fixed or oxidized. (In principle, this process corresponds to the state of the art, with the difference that the dye liquors contain urea instead of a carrier.) Depending on the density of the material or the wound body, dyeing with finely divided vat pigments is also possible. There is no linking here.

Due to the odorless nature of urea, however, a continuous procedure is also possible. Here, the fiber materials containing m-aramid are first impregnated with the urea-containing vat dye liquor using a suitable applicator. The dye liquors are also referred to as padding liquors. Padding liquor is understood to mean a highly concentrated solution of one or more dyes with which a textile web is impregnated with the aid of a suitable applicator. Suitable application devices are, for example, a padder, a pad, roller or doctor blade systems. A padder is preferably used in the method according to the invention.

After application and an optional pre-drying, the dye is then fixed by a heat treatment. The actual fixing reaction of the dyestuff in the m-aramid fiber takes place according to the technically customary processes by dry heat at temperatures between 150 and 250 ° C or by superheated steam at 120 to 170 ° C. The heat treatment is carried out according to the usual methods of textile finishing. These are known to the person skilled in the art and their design is variable and can be adapted to the particular situation in operation. It can be carried out, for example, by the pad steam (pad steaming method) or by the pad dry method (pad dry heat fixing method). These continuous processes can be carried out, for example, with a damper or a tenter frame or a roller runner. During this heat treatment step, urea acts as a moisture-regulating medium due to its hygroscopicity. As a result, a constantly moist level on the fiber surface is maintained for a relatively long time, so that drying out is avoided and an environment favorable for dye diffusion is thus maintained.

The m-aramid materials dyed by the process according to the invention are distinguished by good to very good color fastnesses. In contrast to conventional carriers, the fastness properties are not adversely affected by the addition of urea. This is due to the fact that the urea is completely removed in the washing processes after the dyeing, while with conventional carriers, depending on the intensity of the washing processes, more or less large amounts can still be analytically detected (see Example 1). Carriers that may be mentioned are, in particular, benzyl alcohol, 2-phenoxyethanol, acetophenone, phenols such as o-phenylphenol or chlorocresols. The amount of carrier that can be analytically determined by chromatography in the dyed m-aramid fibers produced according to the invention is therefore below the detection limit, but is <0.1 ppm.

Particularly good lightfastness grades are possible with the vat pigment process. The combination of a padder and a tenter frame is suitable as a preferred method for coloring m-aramid vat pigment. The concentration of the vat dye pigments and the urea in the dye liquor can be varied over a wide range. The concentration of the vat dye pigments is usually based on the usual specifications. This includes the color depth to be achieved and the desired color shade. The preferred urea concentration in the padding liquor is between 0.1 mol ^-1 and 6.5 moles | ^-1 , preferably between 1.5 and 4 mol | ^-1 and particularly preferably between 2.3 and 3.5 mol | ^-1 .

In addition to one or more vat pigment dyes and urea, the dye liquor according to the invention can also contain further auxiliaries. Mention should be made of migration inhibitors, leveling aids, defoamers, softening aids, complexing agents and sequestering agents as well as salts. Further additives are not excluded as long as they do not negatively affect the stability of the dye liquor.

A particular advantage of the process according to the invention results when the vat dyes are used as a mixture. In contrast to a coloration in the spinning mass, this enables graduated bi- or trichrome colorations, the realization of which is desirable for the purpose of achieving certain original color shades. This means that in addition to special color tones, colors in melange tones are also possible. Dyed fiber materials containing m-aramid are obtained which are characterized by lightfastness DIN EN ISO 105 B-02 (50 ° C and 72 h exposure) of at least 4, a wash fastness after DIN EN ISO 105-C08 of at least 4 as well as a rub fastness DIN EN ISO 105-X12 dry by at least 2-3. It is particularly advantageous if the lightfastness of the fiber materials containing m-aramid dyed according to the invention is at least 4-5, their washfastness at least 4-5 and / or their rubfastness at least 3. Commercially available vat dyes can be used to implement the invention.

When implementing the invention, the person skilled in the art is free to use suitable preliminary experiments to select those vat dyes which are particularly advantageous within the scope of the invention.

In contrast to spun-dyed fibers, the dyed fibers produced by the process according to the invention also no longer contain any spinning solvents, since these are largely extracted from the fiber in the course of the dyeing and subsequent rewashing. Spinning solvents that are particularly harmful to health or that are classified as CMR substances, such as dimethylacetamide, dimethylformamide or dimethylimidazolidinone, should be mentioned. The content of spinning solvent in the m-aramid fibers dyed according to the invention is less than 1 ppm.

Another advantage of the method according to the invention is that the elastic properties of the dyed m-aramid-containing textiles are largely retained. The method according to the invention is therefore also particularly suitable for dyeing knitted goods due to the milder fixing conditions that prevail. The action of carriers leads to increased swelling of the fibers and increased mobility of the molecular chains of the m-aramids under the hydrothermal conditions of HT dyeing. After drying, knitted fabrics therefore generally have a stiffer fabric handle and reduced elasticity, which is perceived as annoying. By eliminating carriers from the dye liquor, this swelling step is omitted in the process according to the invention. Hydrotropic substances such as urea have only a marginal influence on fiber swelling in m-aramid fibers, so that the elasticity of the knitted fabrics obtained with the dyeing process according to the claims is largely retained (see Example 6).

When dyeing fiber blends made of m-aramid with other flame-retardant fibers such as viscose FR, Modal FR or Lyocell FR (FR = flame retardant), the flame retardant added to the cellulose fiber is not extracted. As a result, the flame resistance of corresponding fiber blends is hardly changed by the dyeing process. Corresponding experiments with numerical data on the value of the Limiting Oxygen Index (LOI) are given in Example 9. The LOI is a measure of the quality of the flame retardant equipment. The LOI according to ASTM D2863 indicates the limit value of the volume fraction of oxygen in an oxygen / nitrogen gas mixture at which a textile fabric is still burning from top to bottom. The higher the LOI value, the better the flame retardant effect. From an LOI of 24, one speaks of flame-retardant properties and values of 27 and higher, of self-extinguishing properties. According to general consensus, inherently flame-retardant fiber materials with the addition “FR” (FR = flame retardant) have an LOI of at least 28. The LOI of common Nomex ^® items is between 28 and 30.

The invention is to be explained in more detail with the aid of the following examples.

• Gerät: Xenotest Beta LM der Fa. Atlas
• Lichtechtheit bei 50 °C
• Bewertung nach 72 Stunden Belichtung

The lightfastness was determined in all examples DIN EN ISO 105-B02 , July 2002:

• Device: Xenotest Beta LM from Atlas
• Lightfastness at 50 ° C
• Evaluation after 72 hours of exposure

• Prüfung A1M mit Mehrfaser-Begleitgewebe
• 40°C / 150 ml / 45 min / 10 Stahlkugeln
• 4 g/l Skip-Waschmittel (ohne opt. Aufheller)

Determination of wash fastness according to EN ISO 105-C08:

• Examination A1M with multifiber accompanying fabric
• 40 ° C / 150 ml / 45 min / 10 steel balls
• 4 g / l skip detergent (without optical brightener)

• Begleitgewebe Baumwolle, ISO 105 - F09

Determination of the rubbing fastness dry / wet according to EN ISO 105 - X12:

• Cotton accompanying fabric, ISO 105 - F09

Example 1 (exhaust dyeing of piece goods):

• Farbstoffflotte 1 für den Farbton Oliv:
  • 5% C.I. Vat Green 13, bezogen auf das Gewicht des Fasermaterials
• Farbstoffflotte 2 für den Farbton Pantone:
  • 2,5% C.I. Vat Brown 9 + 2,1% C.I. Vat Orange 29
• Farbstoffflotte 3 für den Farbton Gelblich-Blau:
  • 1,7% C.I. Vat Blue 4 + 0,6% C.I. Vat Green 1 + 0,3% C.I. Vat Yellow 28
• Farbstoffflotte 4 für den Farbton dunkeloliv:
  • 6,0% C.I. Vat Black 9 + 2,5% C.I. Vat Green 1

The dyeings were carried out in the form of exhaust dyeings on the dye tree. A knitted fabric with the name Nomex Comfort ^® , consisting of 93% Nomex ^® , 5% Kevlar ^® and 2% antistatic fibers, was used. Aqueous liquors were made up with the following composition: The liquors each contained 90 g / l urea, 6 g / l stabilized formaldehyde sulfoxylate (Rongal HT reducing agent), 10 ml / l 32.5% by weight sodium hydroxide solution and 2 g / l of a dispersing aid (Naphthalene sulfonate).

• Dye liquor 1 for the color olive:
  • 5% CI Vat Green 13, based on the weight of the fiber material
• Dye liquor 2 for the color shade Pantone:
  • 2.5% CI Vat Brown 9 + 2.1% CI Vat Orange 29
• Dye liquor 3 for the yellowish blue color:
  • 1.7% CI Vat Blue 4 + 0.6% CI Vat Green 1 + 0.3% CI Vat Yellow 28
• Dye liquor 4 for the color dark olive:
  • 6.0% CI Vat Black 9 + 2.5% CI Vat Green 1

The dyeing of the goods was carried out in the wound body (tree) in 400 ml dyeing beakers in a Turbomat (from Ahiba) with a liquor ratio of 1:12.

Coloring:

Heat at 3 ° C / min to 115 ° C, 35 min at 115 ° C
cooling down

• 4 g/l Wasserstoffperoxid (35%-ig), pH 5, 35 min bei Raumtemperatur.

Oxidation:

• 4 g / l hydrogen peroxide (35%), pH 5, 35 min at room temperature.

• 1. Bad: 1,5 g/l Dispergator, 10 min bei 100°C
• 2. Bad: 1 g/l anionaktives Tensid, 15 min bei 100°C
• 3. Bad: deionisiertes Wasser, 10 min bei 100°C
• 4.-6. Bad: deionisiertes Wasser, 80°C, je 3 min

Soaps and rinses:

• 1st bath: 1.5 g / l dispersant, 10 min at 100 ° C
• 2nd bath: 1 g / l anionic surfactant, 15 min at 100 ° C
• 3rd bath: deionized water, 10 min at 100 ° C
• 4th-6th Bath: deionized water, 80 ° C, 3 min each

The following table shows the color depths of the colorations based on the K / S value. The values in brackets for the K / S values and lightfastness ratings represent the corresponding dyeings without the addition of urea. Table 1a: Color depths (K / S values) and light fastness ratings Dye liquor Color depth K / S Lightfastness grade 1 (olive), 440 nm 4.22 (0.73) 4-5 (3) 2 (Pantone), 500 nm 2.60 (0.61) 5 (3-4) 3 (blue-yellow), 600 nm 1.48 (0.35) 5 (4) 4 (dark olive), 600 nm 8.60 (2.70) 5-6 (4)

Comparative example:

The dyeings were carried out identically, with the difference that instead of urea in the dye liquor, 70 g / l benzyl alcohol was added as a carrier (dye liquor "No. BA"). Table 1 V: Color depths (K / S values) and lightfastness ratings for carrier dyeing with benzyl alcohol Dye liquor Color depth K / S Lightfastness grade 1-BA, 440 nm 3.72 3-4 2-BA, 500 nm 2.06 3-4 3-BA, 600 nm 1.35 4th 4-BA, 600 nm 7.90 4-5

The fiber materials dyed with carrier, oxidized and rinsed were extracted with isopropanol in a Soxhlet extractor and the benzyl alcohol content in the extracts was determined by means of HPLC. Based on the fiber weight, the amount of benzyl alcohol averages 0.33% by weight (± 0.3% by weight).

Example 2 (yarn dyeing):

The label Yantai Newstar ^® was wound 50/1 Nm on a dyeing bobbin m-aramid yarn employed. The yarn was dyed in a laboratory bobbin dyeing machine (Mathis AG, CH-Oberhasli) with a liquor ratio of 1: 5.

Dye liquor 5 for the color olive:

• 5% C.I. Vat Green 13 (based on the weight of the fiber material)
• 38 ml / l sodium hydroxide solution 32.5%
• 11 g / l Rongal Reducer HT (regular formaldehyde sulfoxylate)

1. a) ohne weiteren Zusatz
2. b) 30 g/l 2-Phenoxyethanol
3. c) 150 g/l Harnstoff

Variants:

1. a) without further addition
2. b) 30 g / l 2-phenoxyethanol
3. c) 150 g / l urea

• Aufheizen der Flotte auf 60°C und dann mit 3°C/min auf 115°C aufheizen 35 min bei 115°C
• Oxidation, Seifen und Spülen analog Beispiel 1.

Tabelle 2: Farbtiefen (K/S-Werte) und Lichtechtheitsnoten Farbflotte 5 Variante Farbtiefe K/S (440 nm) Lichtechtheitsnote a) 0,81 3-4 b) 3,77 3-4 c) 4,43 4-5 Coloring:

• The liquor is heated to 60 ° C. and then heated to 115 ° C. at 3 ° C./min for 35 min at 115 ° C.
• Oxidation, soaping and rinsing analogous to Example 1.

Table 2: Color depths (K / S values) and light fastness ratings Color liquor 5 variant Color depth K / S (440 nm) Lightfastness grade a) 0.81 3-4 b) 3.77 3-4 c) 4.43 4-5

Example 3 (exhaust dyeing without vatting):

In a Labomat cup dyeing machine from Mathis AG, exhaust dyeing was carried out with dye liquor 2 from Example 1 at a liquor ratio of 1:20, but without the additives sodium hydroxide solution and formaldehyde sulfoxylate (Rongal HT reducing agent). The conditions for the dyeing and the soaping / rinsing process were identical, the oxidation step was omitted. The dyeings contained, on the one hand, 150 g / l urea (= liquor 6) and, on the other hand, 70 g / l benzyl alcohol (= liquor 6-BA). Table 3: Color depths (K / S values) and light fastness ratings Color fleet Pantone Color depth K / S (500 nm) Lightfastness grade 6th 2.15 4-5 6-BA 1.72 3-4

Example 4 (pad steam or block steaming method):

It has tissue called Nomex ^® III of Fa. DuPont du Nemours consisting of 95% Nomex ^®, 5% Kevlar ^® (p-aramid) is used for the experiments. The fabric had a basis weight of 262 g / m ² and moderate crystallinity.

• x,y,z g/l Farbstoff
• 150 g/l Harnstoff (= 2,5 Mol/l)
• 2 g/l Dispergator (Naphthalinsulfonat)
• pH 6-7

1. a) Farbton Pantone (braun):
   • Farbflotte 7: 30,1 g/l C.I. Vat Brown 9 + 25,3 g/l C.I. Vat Orange 29
2. b) Farbton Oliv:
   • Farbflotte 8: 43 g/l C.I. Vat Green 13

The fabric with dimensions of 45 cm x 30 cm was pre-washed and dried in a weakly alkaline medium with the addition of surfactants customary for this purpose. A padding liquor of the following composition was then applied using a padder:

• x, y, zg / l dye
• 150 g / l urea (= 2.5 mol / l)
• 2 g / l dispersant (naphthalene sulfonate)
• pH 6-7

1. a) Pantone color (brown):
   • Color liquor 7: 30.1 g / l CI Vat Brown 9 + 25.3 g / l CI Vat Orange 29
2. b) Olive color:
   • Color liquor 8: 43 g / l CI Vat Green 13

In addition, the liquors without urea were used as a comparison for both color shades and dyed analogously (= liquors no. 9-1 and 9-2).
Fleet pick-up: 70% each
Pre-drying: steamer without moisture 2 min, 100 ° C, 20% fan

• Dämpfer: 5 min, 155°C, 45% Dampf

Fixation:

• Steamer: 5 min, 155 ° C, 45% steam

Subsequent soaping and rinsing were carried out as in Example 1.

The color depth was determined based on the K / S values; for dye liquor 7 (Pantone) at 500 nm and for dye liquor 8 (olive) at 440 nm. The lightfastness scores achieved in each case for the urea-free dye liquors Nos. 9-7 and 9-8 are shown in brackets in Table 4b. Table 4a: Color depths (K / S values) Dye liquor Color Pantone K / S (500) Color olive K / S (440 nm) 7th 2.37 - 8th - 4.10 9-7 / 9-8 0.82 1.13 Table 4b: Lightfastness ratings Dye liquor Lightfastness grade 7 (Pantone) 5-6 (4-5) 8 (olive) 5-6 (4)

Comparative example with carrier:

The dyeings were carried out with identical process parameters. However, instead of urea, two commercially available carriers were used in the formulations.
Dye liquor 10: 30 g / l 2-phenoxyethanol
Dye liquor 11: 70 g / l benzyl alcohol
Dye liquor no. X, y-7: color shade Pantone
Dye liquor No. x, y-8: color shade olive Table 4 V a: Color depths (K / S values) Dye liquor Color Pantone K / S (500 nm) Olive K / S (440 nm) 10-7 / 10-8 2.09 3.61 11-7 / 11-8 2.04 3.45 Table 4 V b: light fastness ratings Dye liquor Pantone Olive 10-7 / 10-8 4th 3-4 11-7 / 11-8 4th 4th

Example 5: (coloring of a highly crystalline m-aramid by the pad-dry, thermosol or block-dry process on the tenter frame)

It was used for the tests, a fabric with the name Nomex ^® 450 of Messrs. Du Pont de Nemours, consisting of 100% m-aramid having high crystallinity. The basis weight was 140 g / m ² , the yarn thickness Nm 60/2. The dyeing recipes corresponded to those from Example 4. The liquor pick-up was 74%. The pre-drying and fixing of the dyeings took place on a tenter frame at 100 ° C / 2 min respectively. 180 ° C / 3 min.

After-soaping and rinsing were carried out as in Example 1. Table 5a: Color depths (K / S values) Dye liquor Color Pantone K / S (500 nm) Color olive K / S (440 nm) 7th 2.76 - 8th - 3.45 9-7 / 9-8 0.46 0.69 11-7 / 11-8 2.41 3.22 Table 5b: Lightfastness ratings Dye liquor Color Pantone Color olive 7th 5 - 8th - 4-5 11-7 / 11-8 4th 3-4 Table 5c: Washfastness ratings / change in color Staining of accompanying tissue: Dye liquor Wool acrylic PES PA 6.6 BW 2.5-CA 7th 4th 4-5 4th 4th 4-5 4th 8th 5 5 4-5 4-5 5 5 11-7 / 11-8 4/4 4 / 4-5 4 / 4-5 3/4 4/5 4 / 4-5 Change of color: Dye liquor Change of color 7th 4-5 8th 4-5 11-7 / 11-8 4 / 4-5 Table 5d: Rubbing fastnesses Dye liquor dry wet 7th 3-4 3 8th 3-4 3 11-7 / 11-8 3-4 / 3 2-3 / 2-3

Example 6: (dyeing a knitted fabric made of Nomex ^® Comfort on the stenter)

It has been used a knitted fabric with the designation Nomex ^® Comfort consisting of 93% Nomex ^®, 5% Kevlar ^® and 2% antistatic fiber.

The liquor pick-up was 93%. The dyeings were predried and fixed on a tenter frame at 100 ° C. for 2 minutes or 180 ° C. for 3 minutes.

Post-washing and rinsing were carried out as in Example 1. Table 6a: Color depths (K / S values) Dye liquor Color Pantone K / S (x nm) Color olive K / S (440 nm) 7th 3.7 - 8th - 4.7 10-7 / 10-8 2.2 0.6 11-7 / 11-8 2.9 4.0 Table 6b: Lightfastness Dye liquor Lightfastness Pantone Lightfastness olive 7th 5-6 - 8th - 5 10-7 / 10-8 4th 4th 11-7 / 11.8 4th 3-4

Hysteresis measurements were carried out on the variously treated knitted fabrics by means of a tensile tester (universal tensile tester from Zwick). The force at 38% elongation and the residual elongation after the load was removed were determined. On the basis of DIN 53835-13, expansion / relief cycles were carried out with a specified yield strength of 38%. The mean values from 5 individual determinations were determined in each case. Table 6c: Values for the force absorption and the permanent elongation in the hysteresis test (with a maximum elongation of 38%) F _38.1 [cN] ε _{rest, 1} [%] F _38.2 [cN] ε _{rest, 2} [%] Starting goods 6,870 9.9 6,000 11.0 colored without additives 5,289 10.9 4,419 12.6 Coloring pantone 8,873 11.1 7,519 11.1 with urea, No. 7 Coloring pantone 4,300 12.4 3,675 12.4 with benzyl alcohol, No. 10-7 F _38.1 and F _38.2 : force at 38% elongation in the 1st and 2nd cycle ε _{rest, 1} and ε _{rest, 2} : permanent elongation after the 1st and 2nd cycle.

• Je höher die Kraftaufnahme und je kleiner die bleibende Dehnung, umso besser verhält sich das Material gefühlsmäßig in seinen elastischen Eigenschaften.

In order to explain:

• The higher the force absorption and the smaller the permanent elongation, the better the material's feel in terms of its elastic properties.

Example 7: (concentration series urea)

Analogously to Example 6, a knitted fabric with the designation Nomex ^® Comfort was used. The procedure was as in Example 6 with variable urea concentration in dye liquors 7 and 8. Table 7: Color depths (K / S values) Urea concentration in the dye liquor [mol / l] Color Pantone K / S (500 nm) Color olive K / S (440 nm) 0 1.18 0.58 1 3.43 4.22 2 3.66 4.69 3 3.61 4.50 4th 3.30 4.45

Example 8: (coloring of a fiber mixture)

There was a fabric of 63% Nomex ^® / 30% viscose FR / 5% Kevlar ^® and 2% antistatic fiber having a basis weight of 290 g / m ² in the dimension of 40 cm x 30 cm, pre-washed, are used.

The two dye liquors 7 and 8 were used. The liquor uptake was 70%. The pre-drying and fixing of the dyeings was carried out analogously to Example 5 in a tenter at 100 ° C / 2 min or 180 ° C / 3 min.

Furthermore, the liquors without urea, but with carrier benzyl alcohol, were used as a comparison for both color shades and dyed analogously (= liquors no. 10-7 and 10-8). Table 8a: Color depths (K / S values) Dye liquor Pantone K / S (500 nm) Olive K / S (440 nm) 7th 2.77 - 8th - 3.97 10-7 / 10-8 1.63 2.71 Table 8b: Lightfastness Dye liquor Pantone Olive 7th 5 - 8th - 4-5 10-7 / 10-8 3-4 3-4

Example 9:

The fiber blended fabric from Example 8 was used and, as described in Example 1 by the vat method, with the urea-containing dye liquor 1 and the benzyl alcohol-containing dye liquor 1-BA in the exhaust process on the dye tree (laboratory dyeing machine “Turbomat” from Ahiba) at a liquor ratio of 1:12 colored. For comparison, a dyeing of the fiber material without the addition of urea or carrier was dyed under identical parameters (dye liquor 1-0). It was then oxidized, re-soaped and rinsed as described in Example 1. After drying and conditioning in a standard climate, the Limiting Oxygen Index of the colored materials was determined in accordance with ASTM D2863. Table 9: Limiting Oxygen Index Dye liquor LOI 1 (with urea) 31.6 1-BA 27.9 1-0 33.4

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102009039606 B3 [0002]
• DE 4335717 A1 [0005]
• WO 9604420 A1 [0006]
• US 6942706 B2 [0008]
• DE 102015114501 A1 [0009]

Non-patent literature cited

• Moore R. F., Weigmann H.-J .: "Dyeability of Nomex Aramid Yarn", Textile Res. J. 56 (1986), 254-260 [0002]
• F. Gähr, S. Berndt in TextilPlus 2018, issue 5/6, pp. 16-19 [0004]
• R. Wolf "Flame Retardant Viscose Rayon Containing a Pyrophosphate" in Ind. Eng. Chem. Res. Dev. 20 (1981), 413-420 [0012]
• DIN EN ISO 105 B-02 [0036]
• DIN EN ISO 105-C08 [0036]
• DIN EN ISO 105-X12 [0036]
• DIN EN ISO 105-B02 [0042]

Claims (19)

Process for the production of colored fiber materials based on m-aramid fibers or fiber blends containing m-aramid fibers subsequently dyed with vat dyes, characterized in that the m-aramid fibers are subsequently dyed with vat dyes by a) vat dyes in a urea or aqueous dispersion containing urea derivatives are applied directly to the m-aramid fibers or the fiber blends containing m-aramid fibers and then the vat pigment is fixed on the fiber materials, or b) the vat dyes by adding reducing agents in an alkaline medium the leuco form are transferred, the resulting vat containing urea and / or urea derivatives and the vat is brought into contact with the m-aramid fibers or the fiber mixtures containing m-aramid fibers, the vat dyes are formed oxidatively from the leuco form and a fixation of the vat dyes the fiber materials is carried out. Procedure according to Claim 1 , characterized in that the m-aramid fibers and the fiber blends containing m-aramid fibers are based on fiber flocks, fiber cables, slivers, rovings, yarns, woven fabrics, knitted fabrics, in particular knitted and knitted fabrics, braids or fleece. Procedure according to Claim 1 or 2 , characterized in that the fiber blends containing m-aramid contain further fibers which can be dyed with vat dyes, in particular in the form of viscose, modal, lyocell, polyamide and / or polypropylene fibers and / or wool. Procedure according to Claim 3 , characterized in that the further fibers are inherently flame-retardant and have an LOI according to ASTM D2863 of at least 23, in particular of at least 27. Procedure according to Claim 3 or 4th , characterized in that the other fibers are present as cellulose, regenerated cellulose, aliphatic, aliphatic-aromatic and aromatic polyamide and / or polyester fibers. Method according to one of the Claims 3 to 5 , characterized in that the further fibers, based on the total weight of the fiber mixtures, make up about 1 to 75% by weight, in particular about 5 to 60% by weight. Method according to at least one of the Claims 1 to 6th , characterized in that the vat dyes in step a) have a particle size of about 0.1 to 3 µm, in particular about 0.2 to 0.8 µm. Method according to at least one of the preceding claims, characterized in that the vat dyes are used in the form of indigo, indigo derivative, anthraquinone, anthraquinone oxazole, anthraquinone carbazole, indanthrone, flavanthrone, benzanthrone or pyranthrone dyes or sulfur dyes. Procedure according to Claim 8 , characterized in that the vat dyes as CI Vat Green 1, Vat Green 13, CI Vat Red 32, CI Vat Red 10, CI Vat Blue 4, CI Vat Blue 20, CI Vat Yellow 28, CI Vat Orange 29, CI Vat Brown 9, CI Vat Black 9 and / or CI Sulfur Black 9 is used. A method according to at least one of the preceding claims, characterized in that the aqueous dispersion in step a) and the vat in step b) are continuously applied with a padder, pad or doctor blade or the contacting with the fiber material is carried out in the form of a discontinuous exhaust process becomes. Method according to at least one of the preceding claims, characterized in that the aqueous dispersion in step a) and the vat in step b) have about 0.1 to 10 mol / l, in particular 1 to 5 mol / l and particularly preferably 2 to 4 mol / l contain urea and / or urea derivative. Process according to at least one of the preceding claims, characterized in that in the aqueous dispersion of step a) the vat dyes in a concentration of 1.5 to 110 g / l, in particular from 5 to 60 g / l, and in the alkaline medium in step b) are contained in a concentration of 0.05 to 30 g / l, in particular 0.2 to 20 g / l. Process according to at least one of the preceding claims, characterized in that after the vat dyes have been formed in step b), an after-soaking step is carried out. Method according to at least one of the preceding claims, characterized in that the fixation of the vat dyes in step a) and step b) is carried out as a) dry heat fixation between 140 and 260 ° C, in particular between 170 and 220 ° C, (thermosol process), b ) Steam setting at a temperature between 100 and 160 ° C, in particular between 110 and 155 ° C, and / or c) exhaust dyeing between 70 and 150 ° C, in particular between 98 and 125 ° C. Method according to at least one of the preceding claims, characterized in that carrier materials, in particular benzyl alcohol, acetophenone or 2-phenoxyethanol, are largely excluded when carrying out the method. Colored fiber materials based on dyed m-aramid fibers or fiber blends containing m-aramid fibers, characterized in that these are colored with vat dyes and have a carrier content of less than 15 ppm, in particular less than 10 ppm, in particular available according to the method according to at least one of the Claims 1 to 15th . Colored fiber materials according to claim, characterized in that the colored fiber materials are in the form of colored fiber flakes, fiber cables, slivers, rovings, yarns, woven fabrics, knitted goods, in particular knitted and knitted fabrics, braids or fleece. Colored fiber materials according to Claim 16 or 17th , characterized in that they have a content of carriers of less than 5 ppm, in particular less than 1 ppm. Use of the colored fiber materials according to one of the Claims 16 to 18th or obtainable by a process according to at least one of Claims 1 to 15th for the production of clothing and equipment, in particular flame-retardant or fire-resistant textiles for personal protective clothing, in particular for military, fire brigade and police personnel, work clothing, face masks and protective hoods (balaclava), gloves, underwear (log-arm-shirts, long -Johns), of covers for hot air balloons or for use in the contract sector.