EP0924334A2 - Process for dyeing textile materials comprising polyester fibres - Google Patents

Abstract

In dyeing polyester textiles in an alkaline dyebath containing a disperse dye at over 100 degrees C, the pH of the dyebath is adjusted by adding a buffer mixture containing glycine and/or a glycine derivative and a caustic alkali before the start of dyeing and then a perborate salt is added to the dyebath. An Independent claim is also included for a dyeing ancillary containing glycine and/or a glycine derivative, a caustic alkali and a perborate salt.

Description

The invention relates to a process for dyeing polyester fibers having textile goods, in which the textile goods in an alkaline containing a disperse dye Dyebath treated at a temperature above 100 ° C. becomes.

By polyester dyeing process at temperatures above 100 ° C - i.e. under overpressure - allows shorter dyeing times than reach under normal pressure. In addition, through-coloring, the compensation of fixation and stretching differences, the color yield and the color fastness under High temperature (HT) conditions improved. However occurs HT conditions in the dyeing processes commonly used the following problem in the acid dye bath: While of the dyeing process are low molecular weight oligomers from the Fiber interior released when spinning continuous polyester fibers occur as by-products. These low molecular weight Oligomers accumulate in the acid dye bath Cooling of the dye liquor on the fiber surface and on the Surfaces of the dyeing devices. Through these deposits the technological properties of the textile goods, such as. Running and grip properties, significantly deteriorated. In addition, the dyeing devices are through the oligomer deposits are dirty. Furthermore, in particular with dark shades when using an acidic Dye baths require reductive or alkaline cleaning processes.

For this reason, the use of alkaline dye baths been proposed. Under alkaline conditions that is Solubility of the oligomers increased. Furthermore, one finds partial saponification of the released oligomers takes place, whereby the unwanted deposits significantly reduced become. Furthermore, alkaline dyeing can be used in many cases no reductive or alkaline aftertreatment become. When using the known acid dye baths the dyeing process is generally the only stage of treatment in acidic medium. By alkaline staining can accordingly avoid a pH change and thus the risk of imported alkali is minimized. Another advantage is that single-bath dyeing of polyester-cellulose fiber blends with direct dyes also become possible in alkaline, which additional Choices for appropriate direct dyes creates. It also becomes alkaline when used Dye bath basically possible, washing out or Desizing polyester fabrics in a bath with the dye to combine. The recrystallization continues of fiber degradation products from splitting and peeling processes prevented by the alkali.

However, there are various problems with alkaline staining that can lead to an unsatisfactory staining result:

On the one hand, the hoped-for reduction of oligomer deposits often not achieved with known alkaline dye baths.

Furthermore, the disperse dyes used in the acid dye bath are sometimes unstable in the alkaline dye bath. The dyes are destroyed by hydrolysis of ester compounds in the side chains of the dye molecules. The degree of this hydrolysis depends to a large extent on the pH of the dye bath during the entire dyeing process. In known processes, the pH is subject to fluctuations that can lead to non-reproducible dyeing results. Another problem is represented by heavy metal ions and multivalent metal ions in the dyebath, the presence of which in varying concentrations cannot be reliably excluded on an industrial scale. The influence of heavy metal and metal ions (eg Cu ²⁺ , Fe ²⁺ ) on the dyeing result is generally considerably greater in the alkaline dye bath than in the acid dye bath. The influence of hardness formers in the water of the dye bath on the dyeing result in alkaline is much greater than in acid. Other substances, such as glucose as a degradation product of size residues, can also have a negative effect on the staining result in alkaline solutions. The stronger influence of the aforementioned substances in alkaline is partly due to the fact that the reduction potential in alkaline is always greater than in acid, so that the dyes can be irreversibly reduced.

Furthermore, the concentration of those dissolved in the dye bath Auxiliary substances limited by the fact that at too high a concentration the generally poorly soluble disperse dyes no longer in solution despite the use of dispersants can be held.

DE 39 38 631 A1 describes a process for dyeing polyester-containing Textile known in the alkaline dye bath, in which the dyebath is an amino acid or an amino acid derivative and an alkali metal salt of the amino acid or the amino acid derivative will be added. With the known method however, the above problems cannot be solved satisfactorily.

The invention is accordingly based on the object a process for dyeing textile material made of polyester and whose fiber mixtures of the type mentioned at the beginning improve that the above problems avoided become. In particular, the deposition of oligomers is said to Dye material and dyeing devices avoided and at the same time a large-scale reproducible, consistently high quality Coloring result can be achieved. Furthermore, according to the invention a dyeing aid can be created with which solves the above problems.

This object is achieved according to one aspect of the invention in that the adjustment of the pH of the dye bath by initially adding a buffer mixture Glycine and / or a glycine derivative and an alkali before starting of the dyeing process, and that the dye bath Perborate salt is added.

In a preferred embodiment of the invention, the pH value of the dyebath by adding a buffer mixture from glycine and sodium hydroxide solution before the dyeing process begins set and the dye bath before the start of the dyeing process Sodium perborate added so that the pH through the effect of the buffer mixture from start to finish of the dyeing process kept essentially constant becomes.

This solution creates a double buffer system, through which a sufficient pH constancy until the end guaranteed the dyeing process and at the same time reductive Processes is counteracted without the disperse dye through the buffer substances from the solution is ousted.

The invention lies inter alia. based on the knowledge that at known alkaline dyeing process, the pH is not sufficient is kept stable. Especially through the saponification the initially set pH value of the oligomers by consumption of alkali towards the end of the dyeing process which has the consequence that initially saponified and dissolved Oligomers fail again. This effect is caused by a powerful buffer mixture counteracted. Furthermore are unwanted pH changes due to acidic or alkaline Dye bath components prevented by the buffer system and thus achieves a constant coloring result.

In a preferred embodiment, a glycine / sodium hydroxide buffer (or glycine / glycine alkali metal salt buffer) is used for buffering, which works chemically as follows:

The protonated form of both end groups is only in acid, the deprotonated form only in alkaline. The zwitterion is deprotonated to the amine by adding the sodium hydroxide solution. In addition to or instead of NaOH, the use of another lye (eg soda or Na ₃ PO ₄ ) is also conceivable. However, it has been found that the best dye stability is achieved with NaOH in each case with the same pH value.

That glycine and sodium hydroxide solution in the context of the invention as a buffer interact through which a pH consistency until the end of dyeing was achieved by experimental variation the ratio of glycine / sodium hydroxide solution. The coloring result was optimal when the components mentioned in one by the corresponding buffer equation the dye bath for the desired pH ratio were added. If the relationship in favor of Shifted alkali, i.e. produces a pH greater than 9.5, this shows an instability of the dyes, i.e. the Coloring is not reproducible. Will the relationship favor of the glycine is shifted, so is the buffer capacity no longer sufficient and the final pH is significantly below 9.0, which leads to a redeposition of the oligomers, or their Degradation products, leads.

Within the scope of the invention, both glycine and a Glycine derivative, in which a hydrogen of the amino group through an organic group is replaced. Unsubstituted Glycine is particularly beneficial because when using a glycine derivative the uptake another proton for acid formation is difficult the setting of the buffer equilibrium slows down. The Show hydrophobic residues of a substituted amine group also an increased dispersing effect, through which the disperse dye is kept longer in the dye bath and thus the dyeing process is extended.

Experiments have further shown that the pH cannot always be kept sufficiently constant with a glycine / sodium hydroxide buffer. This is due to the fact that the available buffer capacity is limited by the fact that too high concentrations of the buffer substances would cause the preferred disperse dyes to precipitate out of the dye bath despite the use of dispersants. However, the maximum available buffer capacity of the glycine / sodium hydroxide buffer is not sufficient to keep the pH sufficiently constant until the end of dyeing in the event of high oligomer amounts. In order to be able to carry out the dyeing process on a large-scale reproducible basis even with a large amount of oligomer, a perborate salt, preferably sodium perborate, is therefore additionally added to the dye bath in accordance with the invention such that hydrogen peroxide as the oxidizing agent and a pH-stabilizing mixture of borax and sodium hydroxide solution according to the following are used at the dyeing temperature Equation is released: 4NaBO ₃ + 5H ₂ O → 4H ₂ O ₂ + Na ₂ B ₄ O ₇ + 2NaOH

The sodium perborate fulfills a double function: on the one hand, borax and sodium hydroxide can stabilize the pH value of the dye bath in the desired dye range. The buffer capacity of the borax is based on hydrolytic cleavage to a low-water polyboric acid. In the following reaction scheme it becomes clear that an equilibrium is created in the presence of borax and sodium hydroxide solution. If sodium hydroxide solution is used to saponify oligomers, further borax can be split, ie the pH is maintained: Na ₂ B ₄ O ₇ + (1 + x) H ₂ O → 2 B ₂ O ₃ .xH ₂ O + 2OH ^- + 2Na ⁺

On the other hand, sodium perborate releases H ₂ O ₂ at the dyeing temperature and thus acts as an oxidizing agent, counteracting reductive processes which can negatively influence the dyeing result in alkaline. In particular, dehalogenation of the dyes by heavy metals is counteracted under reductive conditions. Various other fiber accompanying substances can also have a dye-destroying reductive potential, which is counteracted by the hydrogen peroxide formed. Thus, according to the invention, the sodium perborate acts as a dye stabilizer. On the other hand, oxidation of the dyes, as is desired in order to regress the color pigment, for example when dyeing cellulose fibers with vat dyes, is to be avoided within the scope of the invention. The usable concentration of sodium perborate is limited so that the dyeing result is not adversely affected by the undesirable oxidation of the dyes in this case. Experiments have shown that a buffer system based only on sodium perborate cannot have the required buffer capacity without the dyeing result being adversely affected by damage to the dyes. For this reason, two buffer systems are proposed according to the invention in order to achieve the required buffer capacity without negative effects on the dyes.

Another advantage of using perborate is that that the oxidizing agent only when the dye bath is heated is released; Influences on the cold dye bath are thus locked out. In addition to sodium perborate, it goes without saying also the use of perborate salts with others Cation partners conceivable.

The selected buffer systems together have a sufficient high capacity, are for the desired pH range (around pH 9.3) optimally suitable, ecologically harmless and applicable on an industrial scale.

In an advantageous embodiment of the invention can also be provided that sodium chloride added to the buffer mixture becomes. This keeps the glycine in solution by corresponding to the ionic groups of glycine Counterions are delivered. This avoids that the hermaphrodites agglomerate through mutual attraction. In principle, other ionic compounds are also for this purpose applicable. The NaCl has no direct influence on the buffer effect. About the ion concentration in the dye bath to be kept as low as possible and the dye to precipitate out To avoid NaCl is preferably at most in one stoichiometric ratio to glycine added. On the other hand NaCl is used in known dyeing processes so that the Dye from the dye liquor on the fiber by shifting of the solubility balance pulls or not resolves again in the fleet. The concentrations used for this lie significantly above those in the context of the invention suggested NaCl concentrations.

According to a further aspect of the invention, a sequestering agent with the essential constituents nitrilotriacetic acid and polycarboxylates is added to the dyebath. This combined sequestering agent binds multivalent metal ions and heavy metals as well as water hardness formers, which can negatively influence the dyeing result. The sequestering agent with the essential constituents nitrilotriacetic acid and polycarboxylates has proven to be particularly effective in the pH range from 9 to 10 without a negative influence on the dyes (for example demetallization) or a failure of the dyes to be noted. This particularly good sequestering effect with a minimum amount of use is due to the utilization of the different conditional stability constants of both sequestering agents for different cations in the pH range of interest. Nitrilotriacetic acid in the pH range of 9-12 of interest has a sequestering effect of approx. 200 mg / l for Ca ²⁺ , whereas the optimal sequestering effect of approx. 300 mg / l for Fe ^{3+ is} at pH 1.5-3. This is compensated for by the use of a carboxylate with a sequestering effect of only approx. 60 mg / l for Ca ²⁺ at pH 8-10, but approx. 550 mg / l for Fe ³⁺ at pH 9-12. Nitrilotriacetic acid is therefore particularly suitable for Ca ²⁺ ions, whereas carboxylate is better suited for the sequestration of Fe ³⁺ ions. The sequestering agent is preferably used in connection with the above-mentioned buffer system, but can also lead to a considerable improvement in the dyeing result even when isolated.

In an expedient embodiment of the invention, the initial pH can the dyeing process in the range of about 9.3 to 9.4 lie. The majority are available in this pH range Disperse dyes are still sufficiently stable.

Furthermore, can be provided in a practical embodiment be that the final pH of the dyeing process is 9.0 not less. This is confirmed by a corresponding Buffer capacity reached. This way there will be a failure Oligomers already in solution at the end of the dyeing process reliably avoided because below pH 9.0 are the oligomers and their degradation products when falling Temperatures in the cooling process of the dye are no longer soluble.

The concentration ratio of glycine to sodium hydroxide solution (33%) in the buffer mixture can preferably be about 1.9 or less. The amount of caustic soda should be adjusted that an initial pH of 9.3 to 9.4 is reached becomes. The amount of glycine determines the buffering capacity Compensation for alkali-consuming substances.

The concentration ratio of glycine to sodium chloride is preferably about 1.3.

Furthermore, a dyeing aid is proposed according to the invention, which glycine or a glycine derivative, a lye and contains a perborate salt. The lye - preferably Sodium hydroxide solution - can of course before the dyeing process can also be added separately.

The dyeing process according to the invention is both for pure polyester fibers as well as for mixed fibers, e.g. Polyester / cellulose fiber blends suitable.

The invention will now be described with reference to an example explains:

Example:

2,5 bis 1,3 g Glycin;

1,9 bis 0,8 g NaCl;

0,1 g Natriumperborat;

0,3 bis 0,15 g des Polycarboxylate enthaltenden Sequestriermittels mit dem Markennamen Periquest BSD (Hersteller: Dr. Petri);

1,2 bis 0,6 g Nitrilotriessigsäure;

Zugabe von Natronlauge, bis ein Anfangs-pH-Wert von 9,3 bis 9,4 erreicht wird;

1,0 g Dispergiermittel;

Farbstoff-Trichromie mit hoher Stabilität im Färbe-pH-Bereich:

0,5 g Dorospers Gelb KHM *;

0,7 g Dorospers Rot KRG *;

0,3 g Dorospers Blau KGN *.

To dye 100 g of textile made of pure polyester in a liquor ratio of 1:10, a dye bath with the following ingredients (rest: water) is used. The exact amounts used must be adapted to the water content and the concentration of foreign substances in the dye material:

2.5 to 1.3 g glycine;

1.9 to 0.8 g NaCl;

0.1 g sodium perborate;

0.3 to 0.15 g of the sequestering agent containing polycarboxylates with the brand name Periquest BSD (manufacturer: Dr. Petri);

1.2 to 0.6 g of nitrilotriacetic acid;

Adding sodium hydroxide solution until an initial pH of 9.3 to 9.4 is reached;

1.0 g dispersant;

Dye trichromatic with high stability in the color pH range:

0.5 g Dorospers Yellow KHM *;

0.7 g Dorospers Red KRG *;

0.3 g Dorospers Blau KGN *.

The textile material is made using a standard high-temperature dyeing process dyed at approx. 130 ° C in a dyeing machine. Subsequently only a hot rinse is required. In order to becomes a reproducible coloring with technologically improved Textile produced.

The effect of the dyeing process is shown below using the following Comparative examples explained further:

Comparative Example 1:

From the following comparison of the buffer system consisting of glycine and sodium hydroxide solution with that of sodium hydroxide solution and borax, trisodium phosphate and potassium hydrogen phosphate, it follows that a pH constancy with simultaneous stability of the dyes (confirmed by the slightest deviation from the acidic reference color) is only present in the former system. Furthermore, a drop in pH becomes clear when only alkali is used. Influence of the type of alkali on dye stability and pH constancy Dorospers yellow BRA Dispersol Orange C-GL Type of alkali (amount = pH 9.4) Color deviation for reference coloring End pH Color deviation for reference coloring End pH Delta C Delta H Delta C Delta H 0.16 g / l NaOH 33% - 1.51 0.57 8.2 - 2.82 0.20 8.4 0.2 g / l Na ₂ CO ₃ - 2.19 1.14 8.8 - 3.18 - 1.23 8.7 0.3 g / l Na ₃ PO ₄ - 0.96 - 0.49 8.1 - 3.90 - 2.96 8.2 0.06 g / l Li ₂ CO ₃ 0.23 0.65 8.7 - 2.12 - 1.31 8.9 dye bath according to the invention 0.35 0.48 9.2 - 0.90 - 0.03 9.2 3.2 g / l tri-potassium phosphate 1.5 g / l potassium dihydrogen phosphate - 1.96 1.39 8.1 - 3.48 1.49 8.2 0.05 g / l trisodium phosphate 1.32 0.25 7.8 0.54 1.45 7.7 0.75 g / l NaOH 33% + 2 g / l borax - 11.73 4.43 8.8 - 6.05 2.43 9.0

The reference staining, as well as the alkaline staining performed on polyester crepe. The acid coloring is carried out using 1 g / l Setamol WS (brand name Manufacturer BASF AG, Ludwigshafen) and pH 4.5 by adjustment with acetic acid. The colorimetric evaluation of the color difference is based on of the CIELAB values Delta C and Delta H are reproduced.

Comparative Example 2:

The following is intended to show how the oxidizing agents Ludigol (brand name, manufacturer BASF, Ludwigshafen), perborate and iodate can cancel out the reducing effect of glucose. As can be seen from the color deviations (in ΔL and ΔH), perborate has a sufficient oxidation potential in a concentration of 0.1 g / l, but has no negative effects in the absence of reducing agents. 1 g / l Ludigol 2 g / l Ludigol 5 g / l Ludigol 10g / l Ludigol 10 g / l Ludigol; without glucose Δ L Δ H Δ L Δ H Δ L Δ H Δ L Δ H Δ L Δ H -1.53 -2.64 -1.52 -2.45 -0.44 -1.26 -0.63 -1.42 -2.85 -5.13 0.1 g / l perborate 0.2 g / l perborate 0.3 g / l perborate 0.4 g / l perborate 1g / l perborate Δ L Δ H Δ L Δ H Δ L Δ H Δ L Δ H Δ L Δ H -0.38 -0.91 -0.18 -0.89 -0.33 -0.95 -0.20 -1.02 -0.53 -1.41 Δ L Δ H 1 g / l perborate; without glucose -1.05 -0.99 0.05 g / l iodate 0.1 g / l iodate 0.5 g / l iodate 1 g / l iodate 2 g / l iodate Δ L Δ H Δ L Δ H Δ L Δ H Δ L Δ H Δ L Δ H -0.35 -1.04 -0.31 -1.11 -0.35 -0.99 -0.07 -0.48 0.10 -0.38 Δ L Δ H 2 g / l iodate without glucose -2.84 - 4.94

Claims (11)

Process for dyeing polyester fibers Textile in which the textile is in an alkaline, a dye bath containing disperse dye in a Treated temperature above 100 ° C, thereby characterized that the adjustment of the pH of the dyebath by adding a buffer mixture at least from glycine and / or a glycine derivative and a lye takes place before the dyeing process begins, and that a perborate salt is added to the dyebath. A method according to claim 1, characterized in that the pH of the dyebath by adding an initial Buffer mixture of glycine and sodium hydroxide solution before starting the dyeing process is set, and that the Dye bath before starting the dyeing process sodium perborate is added so that the pH from the beginning to End of the dyeing process kept essentially constant becomes. A method according to claim 1 or 2, characterized in that that added sodium chloride to the buffer mixture becomes. Process for dyeing polyester fibers Textile in which the textile is in an alkaline, a dye bath containing disperse dye in a Temperature above 100 ° C is treated, in particular according to one of claims 1 to 3, characterized in that that the dye bath with a sequestering agent the essential components of nitrilotriacetic acid and Polycarboxylates is added. Method according to one of claims 1 to 4, characterized in that that the initial pH of the dyeing process is in the range of about 9.3 to 9.4. Method according to one of claims 1 to 5, characterized in that that the final pH of the dyeing process is the Not less than 9.0. Method according to one of claims 2 to 6, characterized in that that the concentration ratio of Glycine to sodium hydroxide solution (33%) in the buffer mixture approximately Is 1.9 or less. Method according to one of claims 2 to 7, characterized in that that the concentration of sodium perborate in the dye bath is about 0.1 g / l. Method according to one of claims 2 to 8, characterized in that that the concentration ratio of Glycine to sodium chloride is about 1.3. Dyeing aid for the alkaline dyeing of polyester fibers having textile with a disperse dye at a temperature above 100 ° C, in particular for use in a method according to a of claims 1 to 9, characterized in that the dyeing aid glycine and / or a glycine derivative and contains an alkali and a perborate salt. Dyeing aid according to claim 10, characterized in that the dyeing aid is a sequestering agent with the essential components of nitrilotriacetic acid and contains polycarboxylates.