EP3143193A1

EP3143193A1 - Method for brightening dyed textiles

Info

Publication number: EP3143193A1
Application number: EP15717470.7A
Authority: EP
Inventors: Martin Gruber; Thomas APLAS; Harald Lutz
Original assignee: CHT R Beitlich GmbH
Current assignee: CHT Germany GmbH
Priority date: 2014-04-24
Filing date: 2015-04-15
Publication date: 2017-03-22
Anticipated expiration: 2035-04-15
Also published as: US20170051452A1; TR201904232T4; PT3143193T; CN107109771B; PL3143193T3; WO2015162042A1; ES2729156T3; CN107109771A; BR112016023817B1; MX2016013784A; RS58878B1; DE102014207727A1; BR112016023817A2; EP3143193B1; PE20161487A1

Abstract

The invention relates to a method for brightening dyed textiles and to the textiles thereby produced. The method is characterized by treating the materials with an aqueous liquor containing an organic peroxocarboxylic acid having a hydrophobic group, consisting of at least 5 C atoms, as the active component.

Description

Process for lightening dyed textiles

The invention relates to a process for whitening dyed textiles and the textiles produced therewith.

For several years, there has been a continuing, fashionable trend towards wash out and used-look effects. This leads to an increasing demand for dyed textiles made of cellulose fibers, in particular denim articles dyed with indigo or other dyes, which in further processing steps are lightened or bleached wholly or in places by partly mechanically reinforced (stonewash) washing processes, often in combination with chemical treatments ,

The classic denim, or denim, is a weave of indigo ring-dyed warp yarn and mostly undyed weft yarn. The ring coloration of the warp yarn is the reason for the typical signs of wear that give the jeans their individual appearance in the course of their lives. The only superficially adhering to the yarn dye (usually indigo alone or in combination with sulfur black) is gradually removed by mechanical abrasion during washing and use and the white fiber core emerges increasingly. This is increasingly the case, especially in exposed areas such as seams and wearing folds. Since there is a great need on the part of the consumer to purchase garments with utility optics as new, the provision of the so-called used or vintage look is now one of the most commercially important fashion effects in the leisure sector.

For this purpose, articles made of ring-dyed fabrics are subjected to abrasive scrubbing with enzymes and / or pumice stones, which produce abrasion everywhere on the article in the washing drum. This treatment is often done in combination with a second bath containing a bleaching agent to further lighten the color and to enhance light-dark contrasts. In addition, however, the targeted, local brightening of the articles in the corresponding exposed areas is used as an essential means to give a jeans a really authentic look. For this purpose, the denim surface is first locally limited, for example, on the thighs and buttocks, mechanically roughened by grinding manually. Subsequently, sprayed at these points with a bleaching solution that destroys the dye more or less, depending on the desired intensity of the whitening effect. This creates a deceptively genuine impression of signs of use or wear on a new denim article.

It is generally customary to carry out the treatment for surface lightening of dyed textiles in an aqueous bath in a long liquor with hypochlorites, for example sodium hypochlorite. With chlorine bleach, an easily available, inexpensive and efficient bleaching agent is available, with which a large number of dyes, including indigo or indigoid dyes, can be decolorized oxidatively. However, this approach has the disadvantage that large amounts of (adsorbable organically bound halogens) AOX-polluted wastewater incurred, which often have to be post-treated to comply with regulatory limits. Chlorine bleach is very toxic to aquatic organisms. Therefore, the use of chlorine-based chemicals in environmental and consumer organizations is highly criticized. In principle, the use of hypochlorites is also possible for local lightening, for example by spraying. In practice, however, this method is usually not used due to the strong corrosion and etching effects as well as the poor controllability of the bleaching effect.

For the partial bleaching of denim articles in the spray process, the use of potassium permanganate is state of the art. However, serious disadvantages have come to light here as well in the meantime. For example, potassium permanganate exhibits high toxicity to aquatic organisms and its massive use leads to high levels of heavy metals in wastewater. According to the Chemical Prohibition Ordinance (ChemVerV), the release of potassium permanganate in Germany requires a proof of use in order to prevent misuse for explosives or drugs. Similar restrictions exist in many other countries, making the purchase of potassium permanganate laborious and making stockholding more difficult. In addition, an additional process step to remove the resulting manganese dioxide is also necessary in the spray treatment.

As alternatives for hypochlorite and potassium permanganate a number of approaches have been proposed, but also have serious disadvantages and could not prevail in practice.

For example, vat dyes, especially indigo, can be converted into the soluble leuco form by reducing agents, removed from the fiber, and the textile so lightened. The use of sugars such as glucose, for example, is known for this purpose, as described in EP 0 654 557 A. However, these processes have the disadvantage of working at high temperatures (> 80 ° C.) and high alkalinity (pH> 11) must become. Furthermore, large amounts of wastewater accumulate, which also have an increased biological and chemical oxygen demand due to the high organic load. This problem also occurs analogously when using other reducing agents such as keto compounds, for example hydroxyacetone. In addition, reducing processes for producing local bleaching effects are fundamentally unsuitable since, as in a closed washing drum, an overall reducing environment can not be produced and thus the locally produced leukoform is rapidly reoxidized by atmospheric oxygen.

Furthermore, the use of ozone as an oxidizing agent for lightening dyed cotton fabrics is known (EP 0 554 648 A), but this method has the disadvantage that ozone is a very toxic and corrosive gas. The result is that the handling of ozone in industrial production processes is difficult, since the gaseous ozone produced produced controlled to the treatment unit and excess ozone must be removed again. Local treatments such as denim articles are not possible in this way.

The use of hydrogen peroxide or peracetic acid in the lightening of dyed textiles is also known. However, these substances do not serve as a primary bleaching agent but, for example, to neutralize a cotton fabric which has already been lightened by potassium permanganate or to remove MnO ₂ soils formed (compare WO 92/13987 A).

US 3,384,596 C discloses the use of peroxycarboxylic acids such as monoperoxophthalic acid and m-chloro-peroxobenzoic acid in the presence of alkaline earth salts as a bleaching agent at alkaline pH. US 4,443,352 C proposes the use of monoperoxophthalic acid and its water-soluble salts as a bleach-enhancing component of a powdered detergent formulation. The method called stain bleaching in household washing at alkaline pH. An analogous use of monoperoxophthalic acid magnesium salt is claimed in EP 0 027 693 A.

DE 34 00 950 A discloses the use of monoperoxophthalic acid magnesium salt in combination with an alkali bromide and sulfonamides in a detergent formulation also for spot bleaching in household laundry at alkaline pH.

WO 95/25195 A proposes the use of a hydrogen peroxide source in combination with an iron salt at a strongly acidic pH for bleaching indigo-dyed textiles. This combination has long been known as Fenton's reagent. The process is very complex and not economically feasible in practice, because the iron salt must be applied in an upstream treatment step and removed in a subsequent treatment step using large amounts of complexing agents again. To achieve good effects, a longer treatment time at temperatures of 70 ° C and higher is also necessary, which makes this process very energy-intensive.

This also applies to a further proposal for the lightening of dyed textiles: WO 95/20643 A proposes the use of peroxodisulfates as an oxygen source in combination with a transition metal catalyst. However, peroxodisulfates are subject to the same restrictions as the oxidizing agent according to the ChemVerV, such as permanganate and therefore are not suitable as an alternative under this aspect. In addition, peroxodisulfate solutions are as well as Fenton solutions are not suitable for achieving local effects by spray or brush application.

EP 0 176 124 A2 (AT 44 763 E) relates to the use of a suspension in water containing as bleach component a peroxycarboxylic acid derived from a dicarboxylic acid having 8 to 13 carbon atoms as a castable bleach.

DT 26 20 723 AI relates to bleaching or cleaning agents, in particular with a bleaching effect at low temperatures.

Also known is the lightening of dyed textiles in the presence of an enzyme. Examples are the use of laccase and a hydrogen peroxide source as oxidizing agent (US 5,851,233 C, WO 96/12846 A). These methods are used in practice, but have a number of disadvantages. For example, only indigo content is bleached on denim articles, but not the often used sulfur black. To achieve a strong lightening several treatment baths are necessary, which also makes this process very expensive. Furthermore, this treatment must be carried out in a long liquor, a partial lightening, for example by spraying is not possible.

There is currently no alternative method of using potassium permanganate for the local bleaching treatment of denim articles which finds practical application.

The object of the present invention is therefore to provide a method for whitening dyed textiles, which on the one hand makes it possible to lighten the textile flatly or uniformly in the desired shade, but on the other hand also locally limited, for example, by spraying or brush application in freely selectable intensity to bleach. The process should provide comparable results in its lightening effect as using chlorine-based bleach or potassium permanganate, while significantly reducing potential environmental hazards and dangers. In particular, no environmentally hazardous chemicals should be used and an entry of AOX or heavy metals into the wastewater should be excluded.

Surprisingly, it has been found that organic peroxycarboxylic acids, in particular certain linear or cyclic aliphatic or aromatic peroxocarboxylic acids or dicarboxylic acids containing hydrophobic side groups, preferably alkyl radicals having at least 5 carbon atoms, particularly preferably having 5 to 30 carbon atoms and more preferably having chain lengths of 6 to 10 C-atoms, have a very high whitening effect on dyed textiles. In particular, indigo and indigoid dyes can be bleached under moderate conditions, so that a local treatment, for example by spraying, can be carried out simply and practically.

The term "hydrophobic" usually refers to the association of non-polar groups or molecules of an aqueous environment. This characterizes substances that do not mix with water and usually "roll off" on surfaces.

Non-polar substances such as fats, waxes, alcohols with long alkyl radicals - ie with the exception of methanol, ethanol and propanol - alkanes, alkenes etc. are hydrophobic. Dissolution of hydrophobic substances in water generally results in a so-called hydrophobic effect, and in some small, hydrophobic species, such as methane or xenon, even entropically unfavorable clathrate structures are formed. Therefore, the solubility of these substances in water is generally low. Hydrophobic substances are almost always lipophilic, meaning they dissolve well in fat and oil. Surfaces having a contact angle greater than 90 ° to water are also referred to as hydrophobic. Hydrophobic radicals in the context of the present invention thus include, in particular, a contiguous radical of at least 5 carbon atoms, a carbon chain, which are preferably saturated with hydrogen atoms to form an alkyl radical or an aryl radical.

Particularly preferred bleaching agents according to the invention are aromatic peroxycarboxylic acids consisting of one or more fused aromatic rings, optionally substituted by one or more other peroxycarboxylic acid groups at any position. These aromatic peroxycarboxylic acids of the invention may be further substituted with at least one functional group selected from alkyl, aryl, carboxylate, sulfonate, halide, nitro or hydroxy groups at any point on the aromatic ring system. Preferred examples are: mono- or diperoxo-ortho, -meta or -para-phthalic acid, mono- or diperoxo-4-methyl-o-phthalic acid, mono- or diperoxo-l, 8-naphthoic acid.

The peroxycarboxylic acids may be used both in the acid form and as salts or may also be generated in situ by the addition of activated carboxylic acid derivatives (for example as anhydrides) and a hydrogen peroxide source or otherwise in the process. The salts used are preferably alkali metal or alkaline earth metal salts, for example Li, Na, K, Mg or Ca salts.

It has been found, particularly surprisingly, that the treatment can be carried out particularly efficiently under acidic pH conditions, although it is known to the person skilled in the art that peroxycarboxylic acids, for example peracetic acid, at a pH close to the pKa value, ie in the neutral to weakly alkaline , the highest Have bleaching efficiency. Preferably, the pH of the solution is in the range of 0 to 7, more preferably in the range of pHl to pH5, most preferably in the range of pHl, 5 to pH3.5.

Native and synthetic thickeners, salts such as alkali and alkaline earth sulfates, phosphates and, if required, marking dyes, for example dyes, wetting agents, humectants such as glycerol, urea or dispersants or further auxiliaries, are added as further additives to the application liquor. The use of dyes (markers serves to better visual traceability of the spray course.) This is particularly important in practice, since the violet permanganate strongly colors the spray solution, while the spray solution according to the invention is basically colorless.

The abovementioned pH ranges are established either automatically by the reactants used, but can also be adjusted by further additives. For the purposes of the present invention, the pH of the solution is particularly preferably adjusted with mineral acids or organic acids. Very particularly preferred in this sense are low-volatile acids, that is, acids having a vapor pressure <20 Pa at 20 ° C, such as citric acid, maleic acid, lactic acid, phthalic acid, phosphoric acid, sulfuric acid or hydrogen sulfates.

A variety of methods for contacting the colored substances with the peroxycarboxylic acid are available to the person skilled in the art in this field. Particularly preferred in this sense, the colored substances are brought into contact with a solution containing all or part of the peroxycarboxylic acid or its salts by means of a spraying, dipping or brushing process. With the help of the present invention, a wide variety of textiles or textile fabrics can be brought into contact with the peroxycarboxylic acids. Particularly preferred in this sense are textile fabrics made of cellulose fibers or cellulose fibers in mixture with natural or synthetic fibers, which are dyed with a wide variety of dyes. Particularly preferred according to the present invention, these dyes are selected from the groups of vat, direct or sulfur dyes.

The process of the present invention is particularly suitable for textile fabrics dyed with indigo, indigoid dyes or sulfur black, as well as with combinations of these dyes.

Another embodiment of the present invention includes bleached fabrics obtainable by a method as defined above. Jeans, as defined by these bleached fabrics, are particularly preferred.

The effect of the liquors of the invention in local bleaching treatment was determined in direct comparison to the prior art potassium permanganate.

All peroxycarboxylic acids were used at a concentration which is approximately three times the normality of a 2% potassium permanganate solution used on average today.

The bleaching effect was determined on two different denim products each with determination of the Y values according to CIE with Datacolor International SF 600 plus CT, aperture 30 mm LAV, 4-fold measurement, calibration standard light D 65. As bleaching result, according to the invention, preferably> 40% of the bleaching effect of a standard KMnO solution has been achieved, particularly preferably> 60%, very particularly preferably> 80%.

Exemplary embodiments: Reference example 1:

On two commercially available denim products (denim 1 = non-desized, scraping pretreatment with sandpaper, denim 2 = desized, stonewash treatment), a rectangular area of 120 cm ^{2 was} marked and covered with adhesive film at the edges against the adjacent areas. These areas were uniformly sprayed with 2 g each of an aqueous solution of 20 g / l potassium permanganate (0.38 normal) and the fabric samples were then weighed to control the amount applied. After a contact time of 20 min at room temperature, the fabric samples were neutralized in a washer-extractor together with untreated denim fabric as ballast first 10 min at 50 ° C and a liquor ratio of 1: 8 with 4 g / l sodium bisulfite, then 3 times cold rinsed at a liquor ratio of 1:10 and then dried in a tumbler. The y-value according to CIE (Datacolor International SF 600 Plus-CT, Aperture 30 mm LAV, 4-fold measurement, standard light calibration D 65) was measured on each of the samples thus obtained on and off the spray-treated area Degree of lightening determined by ΔΥ.

The values for denim 1 were ΔΥ = 19.2 and denim 2 were ΔΥ = 35.0. Comparative Example 1

From monoperoxoglutaric acid (MPGS), a normal aqueous solution containing 15% by weight of MPGS, 2.5% by weight of sodium sulfate and 0.4% by weight of xanthan thickener was prepared and adjusted to a pH of 2.9 with phosphoric acid. Of this solution, 2.0 g was applied to both standard denim goods in the same manner as Reference Example 1. After a contact time of 20 min at 60 ° C, the fabric sample was rinsed in a manner analogous to Reference Example 1 without neutralization 1 time at 40 ° C and 1 time cold at a liquor ratio of 1:10 and then dried in a tumbler. Of the samples thus obtained, the Y value according to CIE was measured in each case on and in addition to the spray-treated surface in an analogous manner as Reference Example 1, and the difference determined was the degree of lightening with Δθ.

The results for denim 1 were ΔΥ = 4.7 and for denim 2 ΔΥ = 8.3.

Comparative Example 2:

Analogously to Comparative Example 1, monoperoxomaleic acid (MPMS) was applied in the same manner as a normal aqueous solution containing 13.8% by weight of MPMS, 2.5% by weight of sodium sulfate and 0.4% by weight of xanthan thickener, the same amount being applied to both standard denim goods and measure.

The values for denim 1 were ΔΥ = 4.9 and denim 2 were ΔΥ = 10.5. Example 1 :

Commercially available magnesium bis-monoperoxophthalate hexahydrate (MMPP) as an inormal aqueous solution containing 25% by weight of MMPP, 2.5% by weight of sodium sulfate and 0.4% by weight of xanthan thickener was applied in the same amount to both standard denim goods in a manner analogous to Comparative Example 1 , prepared and measured in the same way.

The results for denim 1 were ΔΥ = 18.7 and for denim 2 ΔΥ = 34.3.

Example 2:

Analogously to Comparative Example 1, monoperoxophthalic acid (MPPS) was applied in the same manner as an inormal aqueous solution containing 16.8% by weight of MPPS, 2.5% by weight of sodium sulfate and 0.4% by weight of xanthan thickener, the same amount being applied to both standard denim products and measure.

The values for denim 1 were ΔΥ = 18.1 and denim 2 were ΔΥ = 32.2.

Example 3:

Analogously to Comparative Example 1, monoperoxycis-cyclohexane-1,2-dicarboxylic acid (MPDCS) as a normal aqueous solution containing 17.5% by weight of MPDCS, 2.5% by weight of sodium sulfate and 0.4% by weight of xanthan thickener was added in the same amount applied on both standard denim products, processed and measured in the same way.

The values for denim 1 were ΔΥ = 12.4 and denim 2 were ΔΥ = 24.5. Example 4:

Monoperoxo-4-methyl-phthalic acid Mg salt (MPMP) was prepared analogously to Comparative Example 1 as a normal aqueous solution containing 18.4% by weight of MPMP, 2.5% by weight of sodium sulfate, 0.4% by weight of xanthan thickener and additionally 1 g / l of a marking dye is applied in the same amount on both standard denim products. The marking dye was removed in the subsequent rinsing steps and only served to make the spray history and the uniformity of the job more visible. The preparation and measurement were carried out in the same manner as in Comparative Example 1.

The values for denim 1 were ΔΥ = 18.9 and denim 2 were ΔΥ = 32.5.

Table: Spray Application on Denim 1 (not desized, sanded)

Table 2: Spray application on denim 2 (desized, stonewash)

Example 5:

From commercially available magnesium bis-monoperoxophthalate hexahydrate (MMPP), several 1 normal aqueous solutions containing 25% by weight of MMPP, 2.5% by weight of sodium sulfate and 0.4% by weight of xanthan thickener were prepared and adjusted to pH values with phosphoric acid 5.5 and 2.5 set. Of these solutions, 2.0 g were applied to the standard denim 2 in the same manner as Comparative Example 1, processed in the same way and measured.

The values ΔΥ obtained are summarized in Table 3.

Table 3: Spray application on denim 2 - pH influence

Efficiency relative

Temperature exposure time Δ CIE too

1 pH) [° C] [min] Y KMn0 ₄

5.5 60 20 10.4 30%

} ί)

i

Monoperoxophthalic-Mg

'3.5 60 20 24.5 70% salt

2.5; 60 20 34, 1 97%

Reference Example 2:

Standard Denimware 2 was treated on a spin-on machine at a liquor ratio of 1: 8 with a liquor containing 15 ml / 1 Na hypochlorite solution (120 g / l active chlorine) for 15 min at 50 ° C. Then it was rinsed twice with cold soft water at a liquor ratio of 1:10 and then in 2 steps first with 4 g / l sodium bisulfite and then with 4 ml / 1 hydrogen peroxide 35% each for 10 min at a liquor ratio of 1:10 and a temperature of 40 ° C neutralized. After drying in the tumbler, the Y-value was determined according to CIE (Datacolor International SF 600 Plus-CT, aperture 30 mm LAV, 4-fold measurement, calibration standard light D 65).

This resulted in a value Y = 19.2 Example 6:

Standard Denimware 2 was adjusted to a pH of 3.0, 20 on a washer-spinner at a liquor ratio of 1: 8 with a liquor containing 20 g / L magnesium bis-monoperoxophthalate hexahydrate (MMPP) and adjusted with citric acid min treated at 60 ° C. The mixture was then rinsed twice with soft water at 40 ° C. at a liquor ratio of 1:10. After drying in the tumbler, the Y-value was determined according to CIE (Datacolor International SF 600 Plus-CT, aperture 30 mm LAV, 4-fold measurement, calibration standard light D 65).

This resulted in a value Y = 17.8

Claims

claims:

1. A process for lightening colored textile materials, characterized in that the substances are treated with an aqueous solution (liquor) comprising an aliphatic or aromatic organic peroxocarboxylic acid having a hydrophobic radical, in particular alkyl radical or aryl radical, consisting of at least 5 C atoms contains as active component.

2. The method according to claim 1, characterized in that is used as peroxycarboxylic an aromatic carboxylic acid having one or more percarboxylic groups, optionally substituted with further functional groups, for example, monoperoxo-o-phthalic acid, monoperoxo-m-phthalic acid, monoperoxo-p-phthalic acid , Monoperoxo-4-methylphthalic acid and / or monoperoxol-8-naphthalic acid.

3. The method according to any one of claims 1 to 2, characterized in that the lightening at a pH in the range of 0 to 7, especially at pHl to pH5, in particular at pHl, 5 to pH3.5 performs.

4. The method according to any one of claims 1 to 3, characterized in that one uses the peroxycarboxylic acids directly in the acid form or as salts or by the addition of activated carboxylic acid derivatives such as anhydrides and a hydrogen peroxide source.

5. The method according to any one of claims 1 to 4, characterized in that the pH of the solution with mineral acids or organic acids, in particular with low-volatile acids such as citric acid, maleic acid, lactic acid, phthalic acid, phosphoric acid, sulfuric acid or hydrogen sulfates.

6. The method according to any one of claims 1 to 5, characterized in that one brings the dyed substances with a spray, dip or brushing process with the peroxycarboxylic acid or its salts containing solution in contact.

7. The method according to any one of claims 1 to 6, characterized in that is added as further additives in the application liquors thickeners, salts, marker dyes, wetting agents, humectants, dispersants and / or other auxiliaries.

8. The method according to any one of claims 1 to 7, characterized in that textile fabrics made of cellulose fibers or cellulose fibers in mixture with natural or synthetic fibers dyed with dyes selected from the groups of vat, direct or sulfur dyes, is used.

9. The method according to claim 8, characterized in that one uses textile fabrics which are dyed with indigo, indigoid dyes or sulfur black and with combinations of these dyes.

10. Bleached textiles obtainable by a process according to one of claims 1 to 9.