EP3412826A1

EP3412826A1 - Treatment of dyed material

Info

Publication number: EP3412826A1
Application number: EP17175164.7A
Authority: EP
Inventors: Christian Bruno SCHIMPER; Paul Sebastian PACHSCHWÖLL; Hubert HETTEGGER
Original assignee: Acticell GmbH
Current assignee: Acticell GmbH
Priority date: 2017-06-09
Filing date: 2017-06-09
Publication date: 2018-12-12

Abstract

The present invention relates to surface treatment of indigo-dyed cellulosic textile material with a chemical composition and subsequent radiation or heating in order to obtain a color change and/or a vintage look of the textile material as well as to textile material obtained by such processes.

Description

Field of the Invention

The present invention relates to surface treatment of cellulosic textile material with a chemical composition, more specifically to a discoloration treatment of an indigo-dyed textile material by application of chemicals and subsequent radiation or heating in order to obtain a color change and/or a vintage look of the textile material and the textile material obtained by such process.

Background Art

In the denim and jeans industry fabric and/or garments are processed for obtaining a faded and worn look. This is usually achieved by the application of mechanical treatment of the textile or garment by pumice stones or rocks in combination with enzymatic action resulting in the so-called stonewash look. In this way color removal of e.g. indigo-dyed textiles is obtained, in which a contrasting pattern of variable color intensities is achieved.
Besides stonewashing and enzymatic treatment a number of physical or chemical or combined methods in dry or wet processing are currently used during textile finishing for obtaining a worn look.
Typical dry mechanical treatment methods are inter alia grinding against an abrasive stone or surface, damaging and breaking by controlled warp removal using pen grinders, patch and repair effects by tearing and re-sewing of the treated area, handsanding using sandpaper or sandblasters.
Another method is to apply CO₂ laser irradiation to indigo-dyed denim garments in order to obtain an artificial used look and effects such as whiskers or moustaches.
Wet chemical methods for obtaining a vintage and worn look on the other hand are based on the use of mainly oxidizing agents for color removal. A number of chemical bleaching agents are currently used in the art for the destruction of dye molecules, in which typically potassium permanganate (KMnO₄), chlorine gas (Cl₂) or sodium hypochlorite (N_aClO) are used as strong oxidants. Due to ecological issues such as emission of heavy metals, toxic and dangerous chlorine gas etc. there is a need for alternative bleaching methods using environmentally friendlier chemicals. This actually represents a big problem so-far unsolved in industrial research and development.
One alternative with this regard is hydrogen peroxide (H₂O₂), however, there are still difficulties with respect to handling and storage of this chemically speaking unstable compound.
Full garment or textile bleaching can also be achieved by ozone treatment, in which special ozone washing machines are used. Although this method is supposed to be - besides hydrogen peroxide - much more ecologic compared to potassium permanganate, this finishing technique is mainly used during final clean-up of ready garments.
Most of the above mentioned methods come along with significant drawbacks so-far unsolved in the art. These may concern the need for significant amounts of water during processing, only minor bleaching effects, difficulties in handling, no possible local treatment, difficulties in storage or disposal, prize, non-natural used look effects, significant amount of wastewater, emission of heavy metals and metal oxides or even health issues for the concerned workers, especially when doing sandblasting with quartz sand or spraying of potassium permanganate without any suitable safety equipment.
Therefore there is still the need for an improved method for creating a vintage or used look on dyed denim fabric or garments.

Summary of invention

It is the objective of the present invention to provide for an improved method for creating a vintage or used look on dyed fabric or garments.
The object is solved by the subject of the present invention.
According the invention there is provided a method for changing the color of an indigo-dyed cellulosic fiber, yarn, fabric, or garment in order to obtain a vintage or used look, wherein said textile material is subjected to a treatment with a basic solution and comprising an activating drying step by dwelling, heating, microwave or laser irradiation.
The composition for bleaching of the indigo-dyed textile material made of natural cellulose fibers or mixtures thereof with artificial chemical fibers includes aqueous solutions of N-methylmorpholine N-oxide (NMMO), dimethyl sulfoxide (DMSO), sodium hydroxide (NaOH), potassium hydroxide (KOH) and/or urea.
One embodiment of the invention relates to a method for bleaching a dyed cellulosic textile material comprising the steps of:

pretreating the textile material with a basic solution,
applying radiation or heat to the textile material, and thereby
creating a color value change.

In some embodiments of the invention the cellulosic textile material is indigo-dyed.
In some embodiments of the invention the basic solution is an aqueous alkaline solution.
In some embodiments of the invention the basic solution comprises NMMO, DMSO, NaOH, KOH, urea, or mixtures thereof. The basic solution may comprise NMMO, NMMO and DMSO, NMMO and NaOH, NMMO and KOH, urea and NaOH, or urea and KOH.
For example, the basic solution may comprise NMMO, or NMMO and DMSO, or NMMO and NaOH, or NMMO and KOH, or NMMO, DMSO and NaOH, or NMMO, DMSO and KOH. In some embodiments of the invention the basic solution may comprise urea and a strong base, for example urea and NaOH, or urea and KOH.
A further embodiment of the invention relates to the method as described herein, wherein the pH of the basic solution is above 7. The pH of the basic solution may be in the range of 8 to 14. In some embodiments of the invention the pH is 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, or 14.0
A further embodiment of the invention relates to the method as described herein, wherein radiation is applied. Radiation may be applied by a laser, a microwave oven or infrared light. In some embodiments of the invention the laser is a carbon dioxide laser.
A further embodiment of the invention relates to the method as described herein, wherein the cellulosic textile material is heat treated. The heat treatment may be conducted in an oven or microwave oven, a tumble dryer, or Stenter machine. In some embodiments of the invention the textile material is heated to dryness.
A further embodiment of the invention relates to the method as described herein, wherein optionally auxiliary agents are used.
In some embodiments of the auxiliary agent is selected from the group consisting of a softener, brightening agent, plastic, silicate, amorphous or crystalline silicon dioxide, a thickening agent, dyestuff used as a marker dye, a wetting agent, a complexing agent, a dispersing agent, and a buffer solution derived from the salt of an acid and the corresponding acid, or mixtures thereof.
A further embodiment of the invention relates to the method as described herein, wherein the ΔL value between the untreated and treated part is greater than 2 (L stands for the lightness in the CIE 1976 Lab color space).
One embodiment of the invention relates to an article obtained by a method as described herein.

Brief description of drawings

Fig. 1: Textile samples treated with solutions as described in Table 1, pre-dried and then laser-treated. Reference = laser-treatment only.

Description of embodiments

In current industrial methods large amounts of water as well as chemicals are used for obtaining a vintage or worn look on fabrics and garments, in which also large amounts of toxic substances and heavy metals are emitted into the environment.
By applying the present invention shortcomings of current methods and the emission of toxic compounds and heavy metals are reduced.
The present invention relates to a method of enabling a worn and/or vintage look of fabrics or garments, wherein said fabric or garment is treated with an aqueous solution comprising DMSO, NMMO, NaOH or KOH and/or urea and subsequent dwelling time or application of heat until dryness.
Heat can either be applied by heating in an oven, microwave irradiation, direct infrared irradiation, or laser irradiation.
By applying heat a chemical reaction is taking place, which is eventually bleaching the dyestuff molecules or degrading them and thus reducing the color intensity of the treated fabric or garment.
One object of the invention is to provide a method for reducing the color intensity of e.g. indigo-dyed denim and/or making patterns and images on a number of different cellulosic textile materials, by applying an aqueous solution comprising DMSO, NMMO, NaOH, KOH and/or urea as active compounds and subsequent laser irradiation. Different N-oxides such as pyridine-N-oxide could also be used, however, due to safety reasons and working conditions it is not recommended to be executed.
It is another object to provide a method that enables more intensive fading effects to the textile material on respective treated areas than sole conventional laser treatment.
With respect to industrial applications one object of the invention is to provide such a method that allows causing fading effects in a continuous process.
In the present invention the term "textile material" or "fabric" are used interchangeably and each refer to fibers, yarns, fabrics, flexible knitted, woven or nonwoven material consisting of a network of natural or artificial fibers (yarn or thread). The textile material may also be used in production of further goods (cloths, garments, carpets, bags, shoes, jewelry, furnishings, artifacts, etc.).
In one embodiment the respective textile material is represented as colored and finished denim good.
In a further embodiment of the invention the respective textile material is represented as a variety of garments including jeans skirts, jeans jackets, jeans shorts, jeans vests, jeans dresses, and/or corduroy and twill garments.
In another embodiment of the invention other cellulosic fabrics besides denim are treated according to the described methods.
The textile material may be dyed or coated with a dye, in which the dye may be selected from natural or synthetic dyes, preferably indigo dye, sulfur dyes and other dyestuff classes (e.g. dischargeable dyes etc.), or combinations thereof as top, bottom or mixtures.
The said textile material may be of cellulosic origin and selected from natural fibers, such as bast fibers like jute, flax, hemp, leaf fibers such as sisal, seed fibers such as cotton, or bamboo fibers, or man-made fibers such as lyocell fibers, viscose, rayon type fibers, modal, cupro and/or acetate type cellulosic fibers and optionally mixtures with synthetic fibers, if applicable and chemically compatible.
The active compounds may be selected from DMSO, NMMO, NaOH, KOH and/or urea as active compounds.
It is known from US4196282 to dissolve cellulose in a mixture of water and NMMO for the production of man-made cellulosic fibers etc., however, NMMO is used in this application as a solvent in liquid state and not as an active bleaching agent/oxidant (NMMO is a N-oxide with oxidative power) during application of heat and drying as discussed in the present invention.
In a preferred embodiment the solution is an aqueous solution of NMMO, preferably in the range of 1-98 % NMMO, more preferably 5-95 %, most preferably 25-80 %.
In a further embodiment DMSO is added to the said aqueous NMMO solution or used as a substitute of water, preferably in the range of 1-60 %, more preferably 10-55 %, most preferably 30-50 %.
In a further embodiment sodium hydroxide (NaOH) or potassium hydroxide (KOH) is added to the said solution, preferably in the range of 0.1-50 %, more preferably 1-45 %, most preferably 1-40 %.
In a further embodiment of the invention an aqueous mixture of a strong base in combination with urea is used, in which preferably 1-50 % urea are used, more preferably 10-40 %, most preferably 20-35 %. The said strong base may be selected from the group of alkali, alkali earth, transition metal or metal hydroxides, oxides or carbonates respectively, or more generally speaking substances chemically classified as Arrhenius bases, including ammonia and organic bases. Mixtures of two or more of these compounds may also be used, as well as combinations to form buffer solutions.
In the most preferred embodiment the base is either NaOH or KOH due to economic and ecologic reasons.
Additionally further textile auxiliary chemicals may be added to the said solution in any combination and concentration in solid or liquid form to improve the usability and performance of the said solution according to what is required: e.g. dispersants, wetting agents, surfactants, thickening agents, colorants, tinting agents, silicones, leveling agents, antifoams, antimigration agents, antibackstaning agents, softeners, stabilizers and optical brightening agents. These additives are well known to persons skilled in the art and can be chosen according to commonly used concentrations depending on the desired effect, e.g. 0.001 to 10 %. Other chemicals may be added to impart more desirable improvement of the substrate in hand feel or other property like softness, waterproofing, anti-microbial or microbe reducing chemicals, encapsulated perfumes, etc., or co-solvents (alcohols, ketones, nonionic solvents, ionic solvents, ionic liquids, etc.).
Respective thickening agents may be selected from but not limited to compounds which are commonly used in textile auxiliaries, food additives, cosmetics and personal hygiene products, i.e. starched and modified starches, cellulose and modified cellulose (i.e. methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, ethylhydroxyethyl cellulose), alginates (i.e. sodium-, potassium-, ammonium-, propylenglycol alginate), gummi arabicum, carrageen, agar-agar, locust bean gum, guar gum, tragacanth, gellan, pectin, gelatin.
The said solution is preferably an aqueous solution, but it may be also applied separately and stepwise or as a mixture of the pure substances in powdered form. One or more components may be encapsulated in solution or solid form. In a further embodiment the textile material may also be evenly or unevenly impregnated with said composition using any of the conventional techniques.
As respective techniques of application of one or more components together or in separate form onto the fabric, yarn or garment the following techniques well known to a person skilled in the art may be used at any stage of processing: immersion, padding, spraying, brushing, printing, foaming, sponging, other contact method like stone and/or powder carrier.
In one embodiment of the invention the aqueous solution is applied on the raw or desized denim garment on only limited areas and heat is applied to the whole garment, or covering all parts of the garment and local laser treatment is applied for activation to create localized bleached effects simulating wear areas on the jeans or applied on prepared shaped motif to jeans or fabric which can be subsequently washed to highlight the applied areas.
In another embodiment of the invention the solution may be applied on fabric form by immersion or as a one side application by printing (e.g. as block printing or roller cage printing), spraying, foaming, or a kiss roll on all areas of the application side or on limited areas of the application side.
After application of the said solution onto the fabric, garment or yarn, a dwelling or heating step is necessary for activation of the bleaching and decolorizing action, in which also pre-drying before the actual heating/activation is possible for fast processing. This heating step can either be by heating in an oven, microwave irradiation, direct infrared irradiation, or laser irradiation.
Before the actual heating and thus activation step the textile materials can also be pre-dried after application of said solution. This is preferably carried out at <40 °C for 1-60 min in an oven, a tumble dryer or by a drying passage in a Stenter dryer, in which sole ventilation is also possible. The said heating step is additionally possible in an industrial tumble dryer or Stenter machine, in which both pre-drying as well as activation can be carried out sequentially. In one embodiment of the invention the textile material is treated by said solution and then pre-dried at <40 °C and subsequently heated at 100°C for 10 min in a tumble dryer.
In some embodiments of the invention a fabric is treated by said solution and subsequently heated at 100°C for 10 min during a Stenter passage.
In some embodiments of the invention the textile material is treated by said solution and subsequently heated at 100 °C for 10 min in a tumble dryer.
In some embodiments the textile material is treated by said solution, pre-dried at <40 °C for removal of water and subsequently heated by a carbon dioxide laser emitting laser light in the infrared region (λ = 10.6 µm) at certain regions of the textile.
Within the focused region of the laser, the material is subject to very intensive heating within a very small region. Laser energy is absorbed as heat and the material rapidly heats and very importantly laser energy is transferred to chemical energy, in which eventually a chemical reaction is taking place leading to color intensity reduction of dyed textile materials.
According to one embodiment of the invention the pretreated textile material is placed in a laser device and then scanning with a laser beam having a selected wavelength, power density, pulse width, and repetition rate over the textile material is carried out until the desired degree of fading and/or worn appearance or the selected pattern is achieved.
In a further embodiment the color value changes and can be measured in a ΔL value of 2 between the untreated and treated part. L stands for the lightness in the CIE 1976 Lab color space. A color value means the lightness or darkness of the color of the desired effect which can also be referred to as color intensity or the degree of whiteness or degree of brightness.
Through the treatment of the textile with said compounds and solutions it is possible to reduce the overall applied laser power compared to conventional laser finishing in the denim industry. This is very beneficial, since the application of less energy eventually results in less degradation of the cellulosic fibers, thus the physical properties such as tear strength remain largely preserved. Pure laser treatment usually results in dramatic damage and burning of the fibers, thus the textile is destroyed to a certain extent. By applying the method underlying this invention the fiber damage is largely prohibited. Furthermore it is possible to render certain textile materials bleachable by local laser treatment at all, which have not been accessible to laser treatment before due to only modest overall color reduction. In this case higher laser energy input would not help to overcome this industrial problem, since this would only result in a higher degree of fiber destruction and burning.

Examples

The examples which follow are set forth to aid in the understanding of the invention but are not intended to, and should not be construed to limit the scope of the invention in any way. The examples do not include detailed descriptions of conventional methods. Such methods are well known to those of ordinary skill in the art.
A denim fabric or garment was subjected to a singeing treatment, a skewing treatment and a preshrinking treatment. Then, an aqueous solution comprising NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH or freshly prepared urea+NaOH or urea+KOH was applied by immersion.
A denim fabric was subjected to a singeing treatment, a skewing treatment, a preshrinking treatment and a desizing treatment. Then, an aqueous solution comprising NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH or freshly prepared urea+NaOH or urea+KOH was applied to the surface by printing.
A denim fabric or garment was subjected to a singeing treatment, a skewing treatment, a preshrinking treatment and a desizing treatment. Then, an aqueous solution comprising NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH or freshly prepared urea+NaOH or urea+KOH was applied to the surface by brushing.
A denim fabric or garment was subjected to a singeing treatment, a skewing treatment, a preshrinking treatment and a desizing treatment. Then, an aqueous solution comprising NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH was applied to the surface by spraying.
Optionally a pre-drying step (e.g. <40 °C) is applied to the textile and garment samples after application of the respective solutions.
The color changing effect in such pretreated denim fabrics or garments is then generated by applying any radiation (e.g. laser) or heat treatment (e.g. oven or microwave oven).
A denim fabric was subjected to a singeing treatment, a skewing treatment and a preshrinking treatment. Then, an aqueous solution comprising NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH or freshly prepared urea+NaOH or urea+KOH was applied by immersion, followed by drying and laser treatment in a continuous process.
A raw denim garment was desized and dried. Subsequently a solution containing NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH or freshly prepared urea+NaOH or urea+KOH was sprayed or applied by brush or sponge on limited areas or on the whole denim garment.
A raw denim garment is used as it is, or desized, and/or stonewashed or enzyme washed and dried. Subsequently a solution containing NMMO, or NMMO plus a strong base, for example, NMMO+NaOH or NMMO+KOH, NMMO+DMSO, NMMO+DMSO+NaOH, NMMO+DMSO+KOH or freshly prepared urea+NaOH or urea+KOH is sprayed or applied by brush or sponge on specific areas or on the whole garment.
Optionally a pre-drying step (e.g. <40 °C) is applied to the textile and garment samples after application of the respective solutions.
The color changing effect in such pretreated denim fabrics or garments is then generated by applying any radiation (e.g. laser) or heat treatment (e.g. oven or microwave oven).
Table 1 depicts compositions of the (aqueous) solutions which are applied to denim fabrics.
In Figure 1 decolorized indigo-dyed denim textile samples are shown, which have been treated according to herein described methods. The sample solutions as described in Table 1 were applied each onto the fabrics by brush ( solutions 1, 2, 3 and 5); the fabrics were pre-dried at 40 °C for 60 min in an industrial tumble dryer and then subjected to laser-treatment with a CO₂ laser. A textile without brushed solution but just laser-treatment is showed for comparative purposes as well, clearly demonstrating the enhanced bleaching effect of treated samples compared to solely lasered textile.

Claims

A method for bleaching a dyed cellulosic textile material comprising the steps of:
a. pretreating the textile material with a basic solution,

b. applying radiation or heat to the textile material, and thereby

c. creating a color value change.
The method according to claim 1, wherein said cellulosic textile material is indigo-dyed.
The method according to claim 1 or 2, wherein the basic solution is an aqueous alkaline solution.
The method according to any of claims 1 to 3, wherein the basic solution comprises NMMO, DMSO, NaOH, KOH, urea, or mixtures thereof.
The method according to any one of claims 1 to 4, wherein the pH of the basic solution is above 7, preferably in the range of 8-14.
The method according to any one of claims 1 to 5, wherein radiation is applied by a laser, a microwave oven or infrared light.
The method according to claim 6, wherein the laser is a carbon dioxide laser.
The method according to any one of claims 1 to 5, wherein said cellulosic textile material is treated in an oven or microwave oven, tumble dryer, or Stenter machine.
The method according to claim 8, wherein said textile material is heated to dryness.
The method according to any of claims 1 to 9, wherein optionally an auxiliary agent is used.
The method according to claim 10, wherein said auxiliary agent is selected from the group consisting of a softener, brightening agent, plastic, silicate, amorphous or crystalline silicon dioxide, a thickening agent, dyestuff used as a marker dye, a wetting agent, a complexing agent, a dispersing agent, and a buffer solution derived from the salt of an acid and the corresponding acid.
The method according to any one of claims 1 to 11, wherein the ΔL value between the untreated and treated part is greater than 2 (L stands for the lightness in the CIE 1976 Lab color space).
An article obtained according to any of claims 1 to 12.