EP3927879A1

EP3927879A1 - Method for producing coloured fibrous materials and the use thereof

Info

Publication number: EP3927879A1
Application number: EP20705968.4A
Authority: EP
Inventors: Andreas Merkel; Frank GÄHR
Original assignee: Gebr Otto Baumwollfeinzwirnerei & Co Kg GmbH
Current assignee: Gebr Otto Baumwollfeinzwirnerei & Co Kg GmbH
Priority date: 2019-02-19
Filing date: 2020-02-18
Publication date: 2021-12-29
Anticipated expiration: 2040-02-18
Also published as: EP3927879B1; DE102019104203A1; WO2020169614A1

Abstract

The invention relates to a method for producing coloured fibrous material on the basis of m-aramide fibres or m-aramide-fibre-containing fibre mixtures subsequently dyed with vat dyes, wherein the use of a carrier that is harmful to health and the environment can be done away with. This method is characterised in that the m-aramide fibres are subsequently dyed with vat dyes, wherein a) vat dyes in an aqueous dispersion containing urea and/or homologues and/or derivatives of urea are applied directly to the m-aramide fibres or the m-aramide-fibre-containing fibre mixtures, and then a fixing of the vat pigment on the fibrous materials is carried out, or b) the vat dyes are transformed into the leuco form with the addition of reducing agents in an alakli medium, wherein the relevant vat contains urea and/or homologues and/or derivatives of urea, and the vat is brought into contact with the m-aramide fibres or the m-aramide-fibre-containing fibre mixtures, the vat dyes are formed oxidatively from the leuco form and a fixing of the vat dyes on the fibrous materials is carried out. The fibrous materials obtained according to this method can be used advantageously for the production of clothing and items of equipment, in particular flame-retarding or fire-protection textiles for personal protective clothing, in particular for military, fire-fighting and police personnel, workwear or for use in objects. The particular advantage of the method according to the invention is that it provides coloured fibrous materials with high colour fastness and good colour yield, without bringing about a significant loss in elastic properties.

Description

Process for the production of colored fiber materials and their use

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 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 as well as fiber blends containing them is a major problem. In principle, m-aramid fibers can be dyed with selected cationic dyes under high temperature conditions in the exhaust or continuous process (see e.g. Fiebig D., Küster B. , Herlinger H.: "A possibility for continuous dyeing of poly-m-phenylene isophthalamide", textilpraxis intern. 49 (1994), 260-262, 265, 266 or DE 10 2009 039 606 B3). The prerequisite is that Relatively large amounts of carriers (dyeing 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 typical m-aramid, the T _g is about 270 ° C. The glass transition temperature in polymers is the temperature from which the macromolecules in the amorphous areas get 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 because of 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 a 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 when spinning the m-aramids, for example dimethylacetamide (see, for example, Moore RF, Weigmann H.-J.: "Dyeability of Nomex Aramid Yarn", Textile Res . J. 56 (1986), 254-260), 1,3-dimethylimidazolidinone or selected ionic liquids, but such admixtures are prohibited for practical use in dyeing.

Carrier dyeing

Usually, piece dyeing of m-aramids is carried out at around 120 ° C, ie under FIT (flea 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,

Phenoxypropanol or phenoxyethanol. Further compounds which can develop the effect of a carrier are N-cyclohexylpyrrolidone, acetophenone, 1,2,4-trichlorobenzene, 1-methylnaphthalene, o-dichlorobenzene or n-butylbenzoate (Roberts G. and Solanki R. in J. Soc. Dye. Col. 95: 226 and ibid. 427 (1979). Due to their generally low water solubility, the presence of

Emulsifying auxiliaries required so that they 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 to the air and wastewater. At the same time, this means critical Emission behavior is a significant limitation with regard to the available dyeing processes. Coloring is usually done in closed, high-temperature and overpressure-suitable machines. 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 the addition of a carrier, show a relatively poor color yield. At the same time, the light fastness properties are generally poor, even when using highly lightfast disperse dye types (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 which trigger an increased affinity of the fiber surface for various dyes. DE 43 35 717 A1 describes the treatment of aromatic polyamides in an alcoholic solution of a hydrolyzable alkoxysilane such as (3-triethoxysilylpropyl) octadecyldimethylammonium chloride. 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 it produces. 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 for dyeing 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 high affinity especially 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. The dyeing of textiles made of synthetic fibers with vat dyes in an alkaline medium is described in WO 96/04420 A1. 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, 100% m -Ara- mid and eg Nomex ^® Comfort (93% m-aramid, 5% p-aramid and 2% antistatic fibers), analogous to dyeing with cationic dyes, FIT conditions (115 ° C) and 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 light fastness properties are, depending on the dye, at a significantly higher level than in the case of cationically colored aramids. The addition of a carrier in the dyebath generally leads, analogously to the cationic dyeing, to significantly improved color yields, but at the same time the carrier results in a loss of light fastness of 1-2 points.

US Pat. No. 6,942,706 B2 describes a process based on vat acids for dyeing synthetic fibers, which is said to be suitable for providing high depths of color 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 with the Leuko-HT method. Furthermore, in the presence of a carrier, the lightfastness grades also deteriorate significantly here.

DE 10 2015 114 501 A1 describes a method which works without the linking step. The vat pigments are applied using a pigment block 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

All the methods described for the subsequent dyeing of m -aramid fibers, be it discontinuously or continuously, have the disadvantages, firstly, of inadequate color absorption if no carrier is used and, secondly, that the dyed textiles have inadequate color fastnesses, in particular one have poor lightfastness. 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

to be used if necessary, i.e. Incoming orders, to be able to react quickly,

- 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 a high priority in the textile industry. The use of carriers is a major problem from an ecological point of view. They emit a strong odor nuisance at the workplace and they require complex measures with regard to the minimization of emissions and separate disposal of residual fleets containing carriers.

Another problem with carrier dyeing arises when dyeing fiber blends of m-aramid with other flame-retardant fibers, such as 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, for example, R. Wolf “Flame Retardant Viscose Rayon Containing a Pyrophosphate” in Ind. Eng. Chem. Res. Dev. 20 (1981), 413 - 420) 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 required for the aramid content, which leads to a significant loss of the Overall flame resistance of the fiber blend. 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 mostly 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 Flysteresis 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 the carrier dyeing is that the dyed m -aramid fibers still contain residues of carrier which 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 dyeing of m-aramid fibers and fiber blends containing m-aramid which dispenses with the use of carriers that are harmful to the environment and health and still provides good color yields and fastness properties. At the same time, the use of suitable spinning solvents for m-aramids, which act as carrier-like plasticizers, 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 for m-aramid-containing knitted goods 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 method for producing colored fiber materials on the basis of m-aramid fibers or fiber blends containing m-aramid fibers that are subsequently colored with vat dyes, which is characterized in that the m-aramid fibers are Aramid fibers are subsequently colored with vat dyes by a) vat dyes in an aqueous dispersion containing flarnea and / or flomologe and / or derivatives of flarnea are applied directly to the m-aramid fibers or 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 by adding

Reducing agents are converted into the leuco form in an alkaline medium, the resulting vat containing flarnea and / or flomologues and / or derivatives of flarnea and the vat being brought into contact with the m-aramid fibers or the fiber blends containing m-aramid fibers, the

Vat dyes are formed oxidatively from the leuco form and the vat dyes are fixed on the fiber materials.

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 flarnea and / or flomologe and / or derivatives thereof. Surprisingly, it has been found that flarnea has a beneficial effect on the

Dyeing speed and depth without deteriorating the color fastness. Flarnea is a substance that is well tolerated by the environment and the body. Other advantages of flarea 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.

An essential feature of the process is therefore the addition of urea and / or suitable homologues and / or derivatives of urea to the actual dye liquors. In process step a) as well as in process step b), it is essential to add the urea and / or one or more suitable homologues and / or derivatives of urea before the first step of the dyeing process, namely before the vat dye pigment is absorbed (process step a )) or the vat dye in the leuco form (process step b)) on the respective fiber material so that it can develop its effect - analogously to a carrier. In this measure, the use of urea as such is particularly advantageous. However, various urea derivatives are also suitable for replacing these, in whole or in part. When selecting suitable urea derivatives, it is important that these are similar to urea in terms of water solubility. Urea dissolves very well in water. At 5 ° C 97 g / l dissolve and at 25 ° C 1200 g / l. In order to satisfactorily achieve the benefit sought according to the invention, the water solubility of the homologues and derivatives of urea should not deviate too far therefrom. The minimum limit could be a value of 20 g / l at 20 ° C. Urea homologues that still show suitability here include biuret, which is readily soluble in hot water, but significantly less in cold water, namely at 20 g / l at 20 ° C. N, N'-dimethylurea, which is easily soluble in water (765 g / l at 21.5 ° C.), is also suitable. There are also the following Urea derivatives based on substitution are suitable: tetramethyl urea, O-alkyl urea.

The invention can experience a wide variety of advantageous developments, which are initially 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 cables, rovings, 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 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 using 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), which are used in pigment form, is not critical. It is useful if, in process step a), they have a particle size of about 0.1 to 3 mm, preferably about 0.1 to 1.5 mm, in particular about 0.2 to 0.8 mm.

The person skilled in the art is not restricted in the choice of vat dyes. It is considered to be 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. Concretely preferred vat dyes are listed 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 are used.

When applying the aqueous dispersion in process step a) and the vat in process step b), the invention is not subject to any critical restrictions. It is preferred that the aqueous dispersion in process step a) and the vat in process step b) with a padder, a pad or a squeegee can be applied continuously 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 process step a) and the vat in process 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 flarnea and / or Contain flarea derivative. For the broader range from about 0.1 to 10 mol / l, the following advantageous framework conditions also apply: 0.4 to 10 mol / l, preferably 0.6 to 10 mol / l and in particular 0.8 to 10 mol / l.

With regard to the concentration of the vat dyes in the aqueous dispersion after process step a) or in the alkaline medium after process step b), it is preferred that the vat dyes in the aqueous dispersion of process 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 process 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 method step b), an after-soaking step is carried out.

After the application or formation of the vat dyes according to process step a) or process step b), it is preferred that the vat dyes are fixed in process step a) and process 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 are particularly advantageous when there are no carrier materials, it is therefore considered very useful that when carrying out the method, carrier materials, in particular benzyl alcohol, N-cyclohexylpyrrolidone, phenoxypropanol or phen - oxyethanol, are largely excluded.

The particular advantage of the process product obtained according to the invention as such is shown in its use. The use for the manufacture 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, of work clothing, of face masks and protective hoods (balaclava), of gloves, applies Underwear (long-arm-shirts, long-johns), covers for hot air balloons or for use in the contract sector, are particularly preferred.

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 yarn dyeing, such as dyeing on the tree or on the bobbin, are special

advantageous embodiments of the method according to the invention. For the

Working according to the exhaust process is preferably dyed from the vat and under HT conditions in suitable overpressure containers. The leuco dye is initially vat in an alkaline medium by adding a reducing agent, then brought into contact with the fiber material and, after being evenly absorbed, oxidized or fixed. The alkaline medium is preferably brought to a pH of 9 to 13.5, in particular with sodium hydroxide solution, potassium hydroxide solution and / or ammonia from 10 to 11. Vatting is preferably carried out with a

Reducing agent in the form of an HT-stable formaldehyde sulfoxylate or

Flydroxymethanesulfinate. The oxidation or reoxidation of the leuco dye is preferably carried out with hydrogen peroxide or atmospheric oxygen.

Interim measures are possible. The leuco dye on the fiber is advantageously fixed by means of a suitable one

Measures, whereby there are various advantageous options, such as dry heat fixation, steam fixation and coloration. These measures will be discussed below.

In principle, the above application process corresponds to the state of the art, but with the difference that the dye liquors are urea or suitable

Contain urea derivatives instead of a carrier. In particular, it is left to the person skilled in the art to undertake the dyeing according to measure b) or also according to measure a), in which finely distributed vat pigments are used. So there is no connection 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.

Process a) is preferred for the continuous procedure. Working according to method b) is not excluded.

After application and an optionally carried out predrying, the dye is then fixed by a heat treatment when working according to the preferred process variant a). The actual fixing reaction of the dye in the m-aramid fiber is carried out according to the usual technical processes

Dry heat at temperatures between 150 to 250 ° C or using 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 process) or by the pad dry process (pad dry heat fixing process). 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.

If process variant b) is used for the continuous process, the dye liquor is vat before being applied to the fiber material. The heat treatment is carried out technically in accordance with the possibilities set out in the previous section. The fixing reaction in the fiber takes place through subsequent oxidation of the applied dye by suitable oxidizing agents (see above), whereby the dye is converted into its insoluble form.

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 negatively influenced 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 process, 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

Vat dye pigments are usually made on the basis of 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 I ^-1 and

6.5 mol I ^-1 , preferably between 1.5 and 4 mol I ^-1 and particularly preferably between 2.3 and 3.5 mol I ^-1 . Compliance with the following framework conditions is also particularly advantageous: 0.4 to 6.5 mol I ^-1 , in particular 0.6 to

6.5 mol I ^-1 , particularly preferably from 0.8 to 6.5 mol I ^-1 and very particularly preferably 1 to 6.5 mol I ^-1 .

In addition to one or more vat dyes, in pigment form or dissolved in the leuco form, as well as urea and / or urea derivative, the

dye liquor according to the invention 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 additions 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 both in process step a) and in the

Process step b) can be used as a mixture. This enables im

In contrast to a coloration in the spinning mass, graduated bi - or trichrome colorations, the realization of which is intended to achieve specific

Color templates is desirable. 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 a

Light fastness according to DIN EN ISO 105 B-02 (50 ° C and 72 h exposure) of at least 4, a wash fastness according to DIN EN ISO 105-C08 of at least 4 and a rub fastness according to DIN EN ISO 105-X12 dry of 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

Wash fastness at least 4-5 and / or their rub fastness is at least 3. When implementing the invention can be on commercially available

Vat dyes are used. 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 the subsequent rewashing. Spinning solvents that are particularly harmful to health or classified as CMR substances such as dimethylacetamide, dimethylformamide or dimethylimidazolidinone are to be mentioned. The spinning solvent content 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 mobility of the molecular chains of the m-aramids under the hydrothermal conditions of FIT 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 only have 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 gives the limit value of the volume fraction of oxygen in an oxygen / nitrogen Gas mixture again, in 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, 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 ^{® products} is between 28 and 30.

It seems expedient to emphasize the basic idea of the invention again. The teaching according to the invention includes urea or a suitable urea derivative as an essential component in the coloring formulations.

Urea and urea derivatives serve as a substitute for the toxic carriers that are usually used. The amount required is, as determined, preferably in a range that is also customary for carriers (50-100 g / l). In this regard, reference is made to Example 2 below (Table 7). The maximum determined in relation to the color depth is around 2 mol / l urea (corresponding to 120 g / l).

It is assumed that the urea - similar to a carrier - promotes fiber swelling and thus dye absorption.

Tests in the range from 6 to 60 g / l (corresponding to 0.1 to 1 mol) showed color depths according to Table 7 below for olive (Ci. Wet Vat Green 26). Reference is made to Examples 6 and 7 below for carrying out the test.

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

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

Device: Xenotest Beta LM from Atlas

Lightfastness at 50 ° C

Evaluation after 72 hours of exposure

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) 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 / process step b)):

The dyeings were carried out in the form of exhaust dyeings on the dye tree. A knitted fabric called Nomex was used

Comfort ^® , consisting of 93% Nomex ^® , 5% Kevlar ^® and 2% antistatic fibers. Aqueous liquors were made up with the following composition: The liquors each contained 90 g / l flarnea, 6 g / l stabilized formaldehyde sulfoxylate (reducing agent Rongal FIT), 10 ml / l 32.5% strength by weight sodium hydroxide solution and 2 g / l of a dispersing aid (naphthalene sulfonate).

Dye liquor 1 for the color olive:

5% C.I. Vat Green 13 based on the weight of the fiber material

Dye liquor 2 for the color shade Pantone:

2.5% C.I. Vat Brown 9 + 2.1% C.I. Vat Orange 29

Dye liquor 3 for the yellowish blue color:

1.7% C.I. Vat Blue 4 + 0.6% C.I. Vat Green 1 + 0.3% C.I. Vat Yellow 28

Dye liquor 4 for the color dark olive:

6.0% C.I. Vat Black 9 + 2.5% C.I. Vat Green 1

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

Coloring:

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

cooling down

Oxidation:

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

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 light fastness ratings stand for the corresponding dyeings without the addition of urea.

Table 1a: Color depths (K / S values) and light fastness ratings

Comparison example 1:

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

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

Example 2 (yarn dyeing / process step b)):

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 apparatus (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)

Variants:

a) without further addition

b) 30 g / l 2-phenoxyethanol

c) 150 g / l urea

Coloring:

The liquor is heated to 60 ° C. and then to 115 ° C. at 3 ° C./min 35 min at 115 ° C

Oxidation, soaping and rinsing analogous to Example 1.

Table 2: Color depths (K / S values) and light fastness ratings

Example 3 (exhaust dye without vatting / process step a)):

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 (reducing agent Rongal HT). 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 6j and on the other hand 70 g / l benzyl alcohol (= liquor 6-BA).

Table 3: Color depths (K / S values) and light fastness ratings

Example 4 (pad steam or block steaming process / process step a)):

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

The fabric with dimensions of 45 cm × 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, z g / l dye

150 g / l flarea (= 2.5 mol / l)

2 g / l dispersant (naphthalene sulfonate)

pH 6-7 a) Color Pantone (brown):

Dye liquor 7: 30.1 g / l C.I. Vat Brown 9 + 25.3 g / l C.I. Vat Orange 29

b) Olive color:

Dye liquor 8: 43 g / l C.I. Vat Green 13

In addition, the liquors without urea were used as a comparison for both color shades and colored analogously (= liquors no. 9-7 and 9-8).

Fleet pick-up: 70% each

Pre-drying: steamer without moisture 2 min, 100 ° C, 20% fan

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)

Table 4b: Lightfastness ratings

Comparative example 2 (with carrier):

The dyeings were carried out with process parameters which are identical to those of Example 4. However, two commercially available carriers were used in the formulations instead of flare.

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)

Table 4 V b: light fastness ratings

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

Process step a))

It was used for the tests, a fabric with the name Nomex ^® 450 of Messrs. Du Pont de Nemours, consisting of 100% aramid m with 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 uptake 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.

Subsequent soaping and rinsing were carried out as in Example 1. Table 5a: Color depths (K / S values)

Table 5b: Lightfastness ratings

Table 5c: Washfastness grades / change in color staining of accompanying fabric:

Change of color:

Table 5d: Rubbing fastnesses

Example 6: (Dying of a knitted fabric made of Nomex ^® Comfort on the tenter frame / process step a)) A knitted fabric with the name Nomex ^® Comfort, consisting of 93% Nomex ^® , 5% Kevlar ^® and 2%

Antistatic fiber used.

The liquor pick-up was 93%. The pre-drying and fixing of the dyeings took place on a tenter at 100 ° C / 2 m in or 180 ° C / 3 min. The amount of flarnea in the liquors was 150 g / l in each case (analogous to Example 4).

Post-washing and rinsing were carried out analogously to Example 1.

Table 6a: Color depths (K / S values)

Table 6b: Lightfastness

Flysteresis 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 unloading 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 im

Hysteresis attempt (with a maximum elongation of 38%)

F _{38, 1} and F _38.2 : force at 38% elongation in the 1st and 2nd cycle

e _{rest, 1} and e _{rest, 2} : Permanent elongation after the 1st or 2nd cycle.

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 / process step a))

Analogously to Example 6, a knitted fabric with the designation Nomex ^® Comfort was used. The procedure was analogous to Example 6 with variable urea concentration in the dye liquors 7 and 8. Table 7: Color depths (K / S values)

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 flare but with carrier benzyl alcohol were used as a comparison for both color shades and dyed in the same way (= liquors no. 10-7 and 10-8). Table 8a: Color depths (K / S values)

Table 8b: Lightfastness

Example 9:

The fiber blended fabric from Example 8 was used and, as described under 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) in a liquor ratio of 1: 12. For comparison, a dyeing of the fiber material was dyed without the addition of flare or carrier under identical parameters (dye liquor 1-0), then oxidized, re-soaped and rinsed as described in Example 1. After drying and conditioning The Limiting Oxygen Index of the colored materials was determined in accordance with ASTM D2863 in a standard climate. Table 9: Limiting Oxygen Index

Claims

1. A method for producing 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 an aqueous dispersion containing urea and / or homologues and / or derivatives of urea are applied directly to the m-aramid fibers or the fiber mixtures containing m-aramid fibers, and the vat pigment is then fixed on the fiber materials will, 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 homologues and / or derivatives of urea, and the vat with the m-aramid fibers or the fiber blends containing m-aramid fibers are brought into contact, the vat dyes are oxidatively formed from the leuco form and the vat dyes are fixed on the fiber materials.

2. The method according to claim 1, characterized in that the m-aramid fibers and the fiber blends containing m-aramid fibers on fiber flocks, fiber tows, slivers, rovings, yarns, woven fabrics, knitted fabrics, in particular knitted and knitted fabrics, Braids or fleece are based.

3. The method according to claim 1 or 2, characterized in that the m-aramid-containing fiber mixtures 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.

4. The method 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.

5. The method according to claim 3 or 4, characterized in that the further fibers are present as cellulose, regenerated cellulose, aliphatic, aliphatic-aromatic and aromatic polyamide and / or polyester fibers.

6. The method according to any one of 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.

7. The method according to at least one of claims 1 to 6, characterized in that the vat dyes in method step a) have a particle size of about 0.1 to 3 mm, in particular about 0.2 to 0.8 mm.

8. The method according to at least one of the preceding claims, characterized in that the vat dyes are in the form of indigo, indigo derivative, anthroquinone, anthraquinone oxazole, anthraquinone carbazole, indanthrone, flavanthrone, benzanthrone or pyranthrone dyes or sulfur dyes are used.

9. The method according to claim 8, characterized in that the vat dyes 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 is used.

10. The method according to at least one of the preceding claims, characterized in that the aqueous dispersion in process step a) and the vat in process step b) are continuously applied with a padder, pad or doctor blade, or they are brought into contact with the fiber material in the form a discontinuous exhaust process is carried out.

11. The method according to at least one of the preceding claims, characterized in that the aqueous dispersion in process step a) and the vat in process step b) about 0.1 to 10 mol / l, in particular 1 to 5 mol / l and particularly preferably 2 to Contains 4 mol / l urea and / or urea derivative.

12. The method according to any one of the preceding claims, characterized in that the aqueous dispersion in method step a) and the vat in method step b) are about 0.4 to 10 mol / l, preferably 0.6 to 10 mol / l and in particular contains 0.8 to 10 mol / l urea and / or homologues and / or derivatives of urea.

13. The method according to at least one of the preceding claims, characterized in that in the aqueous dispersion of process 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 an alkaline medium are contained in process step b) in a concentration of 0.05 to 30 g / l, in particular 0.2 to 20 g / l.

14. The method according to at least one of the preceding claims, characterized in that after formation of the vat dyes in process step b), a post-soaping step is carried out.

15. The method according to at least one of the preceding claims, characterized in that the fixation of the vat dyes in process step a) and process 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 fixation 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.

16. The 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.

17. Colored fiber materials based on colored m-aramid fibers or fiber blends containing m-aramid fibers, characterized in that these are colored with vat dyes and have a content of carriers of less than 15 ppm, in particular less than 10 ppm, in particular obtainable by the process according to at least one of claims 1 to 16.

18. Colored fiber materials according to claim 17, characterized in that the colored fiber materials are in the form of colored fiber flocks, fiber cables, slivers, rovings, yarns, woven fabrics, knitted fabrics, in particular knitted and knitted fabrics, braids or fleece.

19. Colored fiber materials according to claim 17 or 18, characterized in that they have a content of carriers of less than 5 ppm, in particular less than 1 ppm.

20. Use of the colored fiber materials according to one of claims 17 to 19 or obtainable by a method according to at least one of claims 1 to 16 for the production of clothing and equipment, in particular of flame-retardant or fire protection textiles for personal protective clothing, in particular for military, fire-fighting and Police personnel, work clothing, face masks and protective hoods (balaclava), flan boots, underwear (log arm shirts, long johns), covers for industrial balloons or for use in the contract sector.