EP0255482A1 - Process for the simultaneous lixiviation and dyeing of cotton textile goods - Google Patents

Abstract

A process for the simultaneous leaching and dyeing of textile material made of cotton and vat dyes by the pad-steaming process is described, in which after padding with a dyeing liquor and drying the textile material, it is subjected to a leaching step and then treated as usual.

Description

This invention a new method for the simultaneous leaching and dyeing of textile material from cotton.

In practice, cotton fabric is very often mercerized or leached before or after dyeing, and it is treated with concentrated alkali solutions. Such an alkaline treatment of the cotton is carried out for various reasons. For example, improves the feel and gloss of the fabric and increases the dyeability.

Another important aspect of leaching is the improvement in the dyeability of dead and immature cotton.

In practice, the alkaline treatment is always carried out separately from the dyeing process, i.e. in a special operation. Despite all the precautionary measures, difficulties can still arise. So you get e.g. when dyeing pre -cercerized, tightly knitted fabrics with vat dyes in the block-steaming process, often a restless, sooty product appearance. For example, if you mercerize a beaum wool material dyed with vat dyes, the color change must be taken into account in the subsequent alkali treatment and neutralization.

Since the conditions of this treatment cannot always be strictly observed, it is difficult to avoid color variations from lot to lot.

It is also known to carry out the alkali treatment of the cotton material with an intermediate drying between the alkali treatment and the last washing and drying, it being possible for the fibers to be damaged when using a common alkali strength of 267-345 g / l sodium hydroxide solid (28-33 ° Baumé) . Treatment with an alkaline strength of only 145-240 g / l sodium hydroxide solid (18-26 ° Baumé) has therefore been proposed.

A method has now been found for the simultaneous leaching and dyeing of textile material made of cotton, which does not have the disadvantages listed.

• a) in einer ersten Phase das Textilgut mit einer Färbeflotte klotzt und danach trocknet,
• b) in einer zweiten Phase das getrocknete Textilgut mit einer Alkalihydroxidlösung imprägniert, abquetscht und trocknet,
• c) in einer dritten Phase das so behandelte Gewebe mit einer wässrigen Mischung aus den erforderlichen Reduktionsmitteln entweder foulardiert und dämpft oder auf einem Jigger entwickelt wobei man das behandelte Gewebe sowohl bei der Entwicklung durch Dämpfen als auch bei der Jigger-Entwicklung anschliessend spült, oxidiert, seift, wieder spült und trocknet.

The process according to the invention for the simultaneous leaching and dyeing of textile material made of cotton with vat dyes is characterized in that

• a) in a first phase, the fabric is padded with a dyeing liquor and then dried,
• b) in a second phase, the dried textile is impregnated with an alkali hydroxide solution, squeezed and dried,
• c) in a third phase, the fabric treated in this way is either padded and steamed with an aqueous mixture of the required reducing agents or developed on a jigger, the treated fabric then being rinsed and oxidized both during development by steaming and during jigger development, soaps, rinses and dries again.

According to the method according to the invention, all sheet-like materials of cellulose fibers or of cellulose-polyester fiber mixtures accessible to the known mercerization, primarily pure cotton fabrics and knitted fabrics, can be mercerized.

Lithium, potassium or sodium hydroxide are suitable as alkali metal hydroxides. The use of sodium hydroxide is of particular technical interest.

The alkali metal hydroxides used are, depending on the desired effect, such as deepening of color, increased grip and gloss, or covering dead cotton, in amounts of 20-250 g / l, preferably 60-200 g / l sodium hydroxide.

Suitable dyes which can be used in the process according to the invention are the vat dyes usually used for dyeing or printing cellulose textile materials.

The vat dyes are e.g. for higher fused and heterocyclic benzoquinones or naphthoquinones, for sulfur dyes and in particular for anthraquinone or indigoid dyes. Examples of vat dyes which can be used according to the invention are listed in the Color Index 3rd Edition (1971) Vol. 3 on pages 3649 to 3837 under the names "Sulfur Dyes" and "Vat Dyes". The vat dyes that can be used are largely stable against the treatment according to stage b) and do not suffer any loss of color strength or change in color tone.

The amount of the dyes generally depends on the desired color strength and is expediently 1 to 100 g per kg of goods, preferably 5 to 60 g / kg of goods.

Sodium dithionite (sodium hydrosulfite), for example, is used as a reducing agent for converting the vat dyes into the fiber-affine form of the leuco compound (vatting). The vatting takes place in an alkaline medium. Examples of alkaline compounds include sodium carbonate, sodium bicarbonate, sodium hydroxide, disodium phosphate, trisodium phosphate, borax, aqueous ammonia or alkali donors, such as. eg sodium trichloroacetate used.

The process according to the invention is carried out as follows: The cotton fabric is padded in a foulard with a dye liquor which contains a vat dye pigment, a wetting agent and, if appropriate, a migration inhibitor, squeezed to a liquor absorption of 55-75% and at a temperature of 100-130 ° C dried.

After drying, the fabric is padded at room temperature with an aqueous solution that contains 20-250 g / l solid sodium hydroxide, and optionally an alkali-resistant wetting agent, and squeezed off to a liquor absorption of 60-100%, the dye pigment stored in the fabric only in detaches from the goods to a very small extent.

Then it is carefully dried at a temperature of 100 - 130 ° C. If necessary, the goods padded with lye can be temporarily stored at room temperature for a few hours before drying.

The fabric leaves the drying unit in a stiff state and with a yellow tinge caused by the dried sodium hydroxide solution. The dried fabric can be stored.

The dry fabric is then padded with an aqueous liquor which contains sodium hydroxide, a reducing agent, for example sodium dithionite or the sodium salt of hydroxymethanesulfinic acid, leveling agents and optionally other dyeing aids, either padded and then steamed for 30 to 60 seconds or on a jigger for 30 to Developed for 45 minutes at a temperature of 50-60 ° C with the addition of the previously mentioned products. With both variants in development, the fabric is then rinsed, oxidized, soaped, rinsed again and dried.

The drying unit used for the "dry-lye intermediate stage" can also be used for other purposes, so that one can do without purchasing an actual mercerizing system.

Since the "dry intermediate leaching stage" takes place after the pigment pigment storage, less edge runoff is to be expected than when dyeing mercerized goods. For example, during the mercerization of extra-wide bed sheet fabrics in the case of chainless mercerizing systems in the area of the edges, a compression of the goods, which triggers color processes that can no longer be corrected in the dye application phase (padding / drying).

The process according to the invention can be carried out on cotton fabrics desized and boiled in the customary manner, the color yield being greatly increased compared to an untreated fabric. Unripe cotton, which otherwise interferes with the overall product appearance, is covered. The gloss and feel of the goods are also positively influenced.

The method according to the invention is particularly suitable for starch-sized raw cotton piece goods. Attractive, denim-like light-dark effects can be achieved on this material using the described method. The fabric can be given a vagrant look (gammel look) by means of a subsequent process step such as "stone washing". In this case, additional advantages of the process according to the invention should be mentioned:
- The denim effect is achieved directly on raw cotton fabrics;
- The seed shells present on the raw fabric are partially removed so that they no longer have a disruptive effect on the overall product appearance;
- only slight oxidative damage to the cellulose, since the raw tissue is protected by the existing starch size;
- good whiteness of the goods without special pretreatment;
- Costly process steps such as desizing, boiling and mercerization are not necessary.

The following examples illustrate the invention. Unless otherwise stated, parts and percentages mean parts by weight or percentages by weight.

10 g/l eines Polymerisates des K-Salzes der 2-Acrylamido-2-methyl­propansulfonsäure enthält und auf einer Flottenaufhahme von 65 % durch 2 Passagen auf einem Benz-Laborfoulard abgequetscht und während 1 Minute auf einer Benz-Labortrockenanlage bei 120°C getrocknet. Das trockene Gewebestück wird dann bei Raumtemperatur (18-25°C) mit einer wässrigen Flotte enthaltend 200 g/l Natrium­hydroxid (100 %) foulardiert und auf einer Flottenaufnahme von 75 % abgequetscht und unter kontrollierter Spannung bei 130°C getrock­net. Das trockene Gewebestück wird nun bei Rautemperatur (18-25°C) mit einer Flotte, welche 50 ml/l Natronlauge 36° Baumé und 50 g/l Natriumdithionit enthält, foulardiert, auf eine Flottenaufnahme von 75 % abgequetscht und mit Sattdampf während einer Minute bei 100°C gedämpft. Nach dem üblichen Spülen, Oxidieren, Seifen, Spülen und Trocknen erhält man eine ruhige, brillante Olivfärbung von starker Farbkraft. Example 1: A 100% cotton-cretonne fabric piece bleached but not mercerized is padded with a dyeing liquor containing 40 g / kg of the commercial form of the dye of the formula

Contains 10 g / l of a polymer of the K salt of 2-acrylamido-2-methylpropanesulfonic acid and squeezed out on a liquor absorption of 65% through 2 passages on a Benz laboratory paddle and dried for 1 minute on a Benz laboratory drying system at 120 ° C. The dry piece of tissue is then padded at room temperature (18-25 ° C.) with an aqueous liquor containing 200 g / l sodium hydroxide (100%) and squeezed off on a liquor pickup of 75% and dried under controlled tension at 130 ° C. The dry piece of tissue is padded at room temperature (18-25 ° C) with a liquor containing 50 ml / l sodium hydroxide solution 36 ° Baumé and 50 g / l sodium dithionite, squeezed to a liquor absorption of 75% and saturated steam for one minute steamed at 100 ° C. After the usual rinsing, oxidizing, soaping, rinsing and drying, a calm, brilliant olive color with a strong color is obtained.

5 g/l eines Polymerisates der K-Salzes der 2-Acrylamino-2-methyl­propansulfonsäure, sowie 5 g/l eines alkalibeständigen Netzmittels und auf einer Flottenaufhahme von 45 % durch 2 Passagen auf einem Benz-Laborfoulard abgequetscht, und während 1 Minute auf einer Benz-Labortrockenanlage bei 120°C getrocknet. Example 2: A 100% strong, shell-containing, starch-sized cotton fabric, weight 325 g / m², is padded at room temperature with a dye liquor which is 50 g / l of the commercial form of the dye of the formula

5 g / l of a polymer of the K-salt of 2-acrylamino-2-methylpropanesulfonic acid, as well as 5 g / l of an alkali-resistant wetting agent and squeezed out in a liquor absorption of 45% through 2 passages on a Benz laboratory pad, and for 1 minute on one Benz laboratory drying plant dried at 120 ° C.

The dry fabric is then padded at room temperature (18-25 ° C) with an aqueous liquor containing 200 g / l sodium hydroxide (100%), squeezed off to a liquor pick-up of 65% and dried under controlled tension at 100 ° C.

The dry piece of tissue is padded at room temperature (18-25 ° C) with a liquor which contains 50 ml / l sodium hydroxide solution 36 ° Bé and 50 g / l sodium dithionite, squeezed to a liquor absorption of 60% and saturated steam for 1 minute steamed at 100 ° C.

After the usual rinsing, oxidizing, soaping, rinsing and drying, a color is obtained with uniformly distributed "denim-like" black and white effects.

5 g/l eines Polymerisates des K-Salzes der 2-Acrylamino-2-methyl­propansulfonsäure sowie 5 g/l eines alkalibeständigen Netzmittels enthält und wird auf einer Flottenaufnahme von 70 % durch 1 Passage auf einem Mathis-Laborfoulard abgequetscht, dann während 1 Minute auf einer Benz-Labortrockenanlage bei 120°C getrocknet und auf­gedockt. Example 3: A 100% cotton cretonne piece of fabric, desized and boiled, (140 g / m²) is padded at room temperature (18-25 ° C.) with a dyeing liquor containing 50 g / l of the commercial form of the dye of the formula

Contains 5 g / l of a polymer of the K salt of 2-acrylamino-2-methylpropanesulfonic acid and 5 g / l of an alkali-resistant wetting agent and is squeezed off on a liquor absorption of 70% through 1 passage on a Mathis laboratory pad, then for 1 minute dried and docked in a Benz laboratory drying system at 120 ° C.

The thus treated and dried fabric is then padded at room temperature with an aqueous liquor containing 200 g / l sodium hydroxide (100%) on a Mathis laboratory foulard, squeezed off to a liquor absorption of approx. 70% and at 100 ° C. on a Benz laboratory dryer dried and docked.

The piece of tissue thus obtained is then developed on a Benz laboratory jigger with 10 ml / l sodium hydroxide solution 36 ° Bé and 8 g / l hydrosulfite at 30 ° C for 30 minutes, then rinsed cold in the overflow, treated cold with 10 g / l sodium bicarbonate, oxidized with 2 ml / l hydrogen peroxide (35%) and 2 ml / l acetic acid 80%, soaped at the boil and rinsed cold.

The result is a level, level coloration with a smooth product appearance.

Claims (6)

1. Process for the simultaneous leaching and dyeing of textile material from cotton with vat dyes according to the block-steaming process, characterized in that a) in a first phase, the fabric is padded with a dyeing liquor and then dried, b) in a second phase, the dried textile is impregnated with an alkali metal hydroxide solution, squeezed and dried, and c) in a third phase, the fabric treated in this way is either padded and steamed with an aqueous mixture of the required reducing agents or developed on a jigger, the treated fabric then being rinsed and oxidized both during development by steaming and during jigger development, soaps, rinses and dries again. 2. The method according to claim 1, wherein an aqueous solution containing 20-250 g / l of solid sodium hydroxide is used for step b). 3. The method according to claim 2, wherein the treated textile after phase b) is dried at temperatures from 100 to 130 ° C. 4. The method according to claim 1, wherein the treated fabric in phase c) is steamed for 30 to 60 seconds. 5. The method according to claim 1, wherein the treated textile material in phase c) is developed at a temperature of 55 to 60 ° C for 30 to 40 minutes. 6. The cotton fabric treated by the method according to one of claims 1 to 5.