GB1575220A

GB1575220A - Process for the continuous dyeing of cellulose fibre materials

Info

Publication number: GB1575220A
Application number: GB33333/77A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1976-08-11
Filing date: 1977-08-09
Publication date: 1980-09-17
Also published as: CH613584GA3; BE857701A; FR2361501A1; DE2635992C2; DE2635992B1; CH613584B; NL7708703A; CA1097459A

Abstract

The sheet structures which comprise continuous sheets of tops, card slivers and spread-out tows and consist of cellulose fibres or blends thereof with synthetic fibres are, in a continuous process, a) padded with an aqueous dyeing liquor which is at room temperature, contains at least one sulphur dye reduced to the leuco form and is provided with an addition of a sodium polysulphide (Na2Sx; x = 2-5) which is in aqueous solution and acts as redox buffer, then b) for the purpose of fixing the padded leuco sulphur dye guided through in the plaited state for 1-10 min. at 80-98 DEG C or for 10-60 sec. at 110-220 DEG C, while retaining the moisture applied by the padding, through a heat-fixing chamber which is heated exclusively by hot air, and finally c) subjected to a reoxidation treatment to return the sulphur dye or dyes used to the water-insoluble disulphide form. Tops, card slivers and fibre webs can be dyed by this process without the need for a special steamer. Since no intermediate drying is necessary, time and energy are saved. While the requirement for reducing agent remains the same, an excellent appearance and good fixing even of deeper dyeings are obtained. The dyeings display good fastness. Since the process is a one-bath process, the procedure is simplified.

Description

(54) PROCESS FOR THE CONTINUOUS DYEING OF CELLULOSE FIBRE MATERIALS (71) We, HOECHST AKTIENGESELLSCHAFT, a body corporate organised according to the laws of the Federal Republic of Germany, of 6230 Frankfurt/Main 80, Postfach 80 03 20, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The dyeing of cellulose fibres with sulfur dyestuffs, leuco sulfur dyestuffs and thiosulfato dyestuffs has been known for some time.

For use with these dyestuff classes, continuous pad-dyeing processes are known in which the leuco (sulfhydryl) form of a dyestuff is padded, from cold or warm liquors, onto piece goods moving in full fabric width, is fixed by a steaming process and is reformed on the fibre into the water-insoluble form (disulfide form) of the dyestuff (fundamental form of the "normal" sulfur dyestuffs, starting form for their water-soluble derivatives, such as leuco sulfur dyestuffs and thiosulfato dyestuffs) by an oxidizing after-treatment. In this procedure the leuco form of the sulfur dyestuff or thiosulfato dyestuff is formed in one or two baths by a reducing agent, preferably sodium sulfide.

However, the leuco sulfur dyestuffs are already present as the reduced (sulfhydryl) form and require no addition of reducing agents. In each case the leuco compounds are fixed on the fibre by steaming. When slubbings or card slivers are dyed, a special steamer is required which permits stress-free feeding of the sensitive slivers into the steam chamber.

In practice these classes of dyestuffs are dyed in an analogous manner to a roller vat, that is to say by a continuous exhaustion process, preferably without the steaming operation. The varying affinity properties of the individual dyestuffs and the unfavorable ratio of goods to liquor makes this process particularly difficult. The amount and time of the topping up must be monitored very carefully in order to obtain dyeings which are to some extent free from tailing.

A process for the continuous dyeing of cellulose fibres in which water-soluble sulfur dyestuffs (C.I. Solubilized Sulfur Dyes) are applied to the web of goods by a pad-air passage process is known from German Auslegeschrift No. 2,511,535.

This is a two-stage procedure in which the dyestuffs and the chemicals (in particular reducing agents) are applied in two successive padding processes. The fixing of the dyestuff then takes place during the subsequent air passage. A similar dyeing process for sheet-like structures made of cellulose fibres is described in German Auslegeschrift No. 2,511,536. In this procedure sulfur dyestuffs are padded, in their reduced form, from a hot liquor onto the textile material and are fixed in a subsequent air passage.

The present invention provides a continuous process for dyeing a fibre material, preferably slubbings, card slivers or tow, comprising cellulose fibres or a mixture of cellulose and synthetic fibres, which comprises padding the web-like material, advantageously from a small liquor trough, with an aqueous liquor, at room temperature, which contains one or more sulfur dyestuffs in the reduced form (leuco form) and a sodium polysulfide, introducing the padded material, without intermediate drying, into a dwelling chamber wherein the material is subjected to a hot air treatment, preferably in the pleated state, for a period of from 1 to 10 minutes, preferably from 3 to 7 minutes, at a temperature in the range of from 80 to 980C or for a period of from 10 to 60 seconds at a temperature in the range of from 110 to 220"C, removing the material from the welling chamber and subsequently subjecting the material to a reoxidation treatment to form the water-insoluble disulfide form of the sulfur dyestuff(s). The material may then be after-treated in the usual manner.

All types of sulfur dyestuffs, that is to say the compounds described in the Color Index under the designations C.I. Sulfur Dyes, C.I.

Leuco Sulfur Dyes and C.I. Solubilized Sulfur Dyes, can be used for the process of the invention.

The process of the invention makes it possible, for the first time, to dye continuously slubbings, card slivers or non-woven fabrics made of cellulose fibres or mixtures thereof with sulfur dyestuffs without employing a special steamer. Suitable installations which can be used for the process are, for example, the machines outlines in German Offenlegungsschrift No. 2,406,257.

In the steaming processes which were customary hitherto, the action of atmospheric oxygen on the reduced dyestuffs was excluded by the steam atmosphere. It was, therefore, surprising that in the process according to the invention, wherein the material is treated in the presence of atmospheric oxygen, the amount of reducing agent employed did not need to be increased, and that good fixing results are obtained, even with deep dyeings. The dyeing is advantageously carried out according to the following procedure: A hot aqueous solution of a reducing agent suitable for the vat process, preferably either sodium sulfide or sodium bisulfide and sodium carbonate, is poured over the sulfur and/or thiosulfato dyestuffs, if used, and these dyestuffs are dissolved in this manner.

In this procedure, the leuco form of these dyestuffs is formed. Leuco sulfur dyestuffs, if used, are dissolved by pouring a little hot water over them.

The solution(s) thus obtained of the dyestuff(s) (in leuco form) is/are now brought to the required volume with cold water and 15 to 25 cm3/1 of a 15% strength aqueous sodium polysulfide solution (Na2Sx; x = 2 to 5 on average) are then added. The solution this prepared is used for padding. The padding liquor may also contain one or more fixation auxiliaries.

After the padding operation the material is passed into a dwelling chamber heated with hot air, where it remains whilst passing through continuously, appropriately in the pleated state, for from 1 to 10 minutes, preferably from 3 to 7 minutes, at an air temperature of from 80 to 980C, or for from 10 to 60 seconds at a hot air temperature of from 110 to 2200 C. After the predetermined dwelling time has ended, the dyed goods are removed, again continuously, from the dwelling chamber and passed to a customary aftertreatment (oxidation and soaping processes).

The process according to the invention has the following advantages compared with the corresponding known dyeing methods: it provides a continuous dyeing process for slubbings, card slivers and non-woven fabrics without the necessity of using a special steamer; it gives a simplified procedure since it is a one-bath process; a saving in time and energy is obtained by the omission of intermediate drying and steaming; an outstanding colour result, good fixing and deeper dyeings are obtained; there is no increased requirement of reducing agent; and the dyeings have good fastness properties.

The process according to the invention is particularly suitable for operating at the full capacity of installations envisaged for other dyeing processes, for example continuous thermosol installations for dyeing slubbings made of synthetic fibres, which correspondingly lowers the cost. In general such installations consist of a padding device, a dryer, a thermosol unit and an after-treatment unit. It was surprising that the padded sulfur dyestuffs can also be fixed perfectly when the air circulation and air temperature in the dryer and thermosol unit are appropriately moderated. In addition, moderating the amount of air and the air temperature results in considerable savings in energy.

The following examples illustrate the invention.

Example I For the continuous dyeing of viscose staple slivers, 12 tows were padded with a liquor, at room temperature, which had been prepared as follows: 100 g/l of the dyestuff Leuco Sulfur Green 9 (C.I. No. 53,005) and 15 g/l of the dyestuff Leuco Sulfur Brown 51 (C.I.

No. 53,377) were dissolved in an amount of hot water (85-93"C) which was about 1/10 of the required amount of liquor, and the resulting solution was stirred into the remaining 9/10 of the amount of liquor, consisting of cold water. 3 g/l of a wetting agent based on an alkanesulfonate, and 20 cm3/l of a 15% strength aqueous solution of a sodium polysulfide having an average of from 2 to 5 atoms of sulfur in the molecule (Na2Sx; x = 2 to 5) were also added to this liquor.

The viscose material was padded to give a liquor pick-up of 100% (calculated on the weight of the dry goods), and was fed continuously and without intermediate drying into a batching chamber according to Figure 1 of German Offenlegungsschrift No.

2,406,257, in which the air temperature was 95"C and the air circulation was low. The slivers were allowed to remain therein for 10 minutes, lying on the conveying devices of the chamber, and were then removed, again continuously, from the dwelling zone. Rinsing, oxidation at 800C with an aqueous bath containing 5 cm3/l of 60% strength acetic acid and 2 g/l of sodium bichromate, and further rinsing with water were carried out in the subsequent treatment sections, also operating continuously, of an open-width washing installation.

Uniform deeply olive-coloured slubbings were obtained.

Example 2 Viscose staple sliver was dyed on a continuous thermosol installation (normally used for dyeing slubbings of synthetic fibres, for example polyester fibres) consisting of a padder, perforated drum dryer, perforated drum thermosol device and after-treatment unit. For this process the temperatures in the dryer and in the thermosol installation were lowered to 900C. The fresh air feed was reduced to about 5%. The air circulation conditions were not reduced or were only slightly reduced, in order to ensure the reliable feed of the slubbings.

The slubbings were padded, at a liquor pick-up of 90% (calculated on the weight of the dry goods), with an aqueous padding liquor having a temperature of 20"C and consisting of 45 g/l of Sulfur Brown 10 (C.I.

No. 53,005), 30 g/l of Sulfur Red 6 (C.I. No.

53,720) and 25 g/l of Sulphur Brown 16 (C.I. No. 53, 285) which had been dissolved by having poured over them a hot aqueous solution of 80 g/l of sodium sulfide (technical grade, crystalline) in an amount which was about 1/10 of the total amount of liquor required. This solution was mixed with the remaining 9/10 of the amount of liquor, consisting of cold water, and 25 g/l of a 15% strength aqueous sodium polysulfide solution CNa2Sx; x = 2 to 5) were also added.

The padded slubbings were fed continuously into the installation as described above, through which they passed in 3 minutes.

After leaving the thermosol unit the goods were after-treated as described in Example 1.

A strong, level brown dyeing of the viscose staple slivers was obtained.

Example 3 Card slivers made of cotton were dyed in an installation according to Figure 3 of German Offenlegungsschrift No. 2,406,257 with an aqueous padding liquor which consisted of: 35 g/l of Solubilized Sulfur Green 9 (C.I.

No. 53,006), 10 g/l of Solubilized Sulfur Brown 60 (C.I. No. 53,326), 120 cm3/l of a 20% strength aqueous solution of sodium bisulfide, 15 cm/lofa 15% strength aqueous solution of a sodium polysulfide (Na2Sx; x = 2 to 5), 20 g/l of calcined sodium carbonate and 3 g/l of a wetting agent based on an alkanesulfonate.

The material was padded continuously at room temperature and at a liquor pick-up of 100% (calculated on the weight of the dry goods), and the padded slivers were placed in the installation at an air temperature of 95"C. After a dwelling time of 8 minutes, the slivers were removed, again continuously, from the installation and after-treated as described in Example 1.

A uniform, strong olive dyeing was obtained.

Example 4 An aqueous padding liquor was prepared from 60 g/l of Solubilized Sulfur Blue 7 (C.I.

No. 53,441), 6 g/l of Solubilized Sulfur Brown 16 (C.I. No. 53,286), 80 g/l of sodium sulfide (technical grade, crystalline), 15 cm3/l of a 15% strength solution of a sodium polysulfide (Na2Sx; x = 2 to 5) and 3 g/l of an anionic wetting agent based on an alkanesulfonate, and a non-woven fabric made of cotton was padded to give a liquor pick-up of 80% (calculated on the weight of the dry goods). The padded non-woven fabric was fed to a perforated drum unit and treated in this with hot air at 1800C for 30 seconds. In the hot air section of this unit, only the feed of fresh air was moderated to 10%. Thereafter, the non-woven fabric was subjected to an after-treatment as described in Example 1. A deep, uniform navy blue dyeing was obtained.

WHAT WE CLAIM IS: 1. A continuous process for dyeing a fibre material comprising cellulose fibres or a mixture of cellulose and synthetic fibres, which comprises padding the material with an aqueous liquor, at room temperature, containing a sulfur dyestuff (as hereinbefore defined) in the reduced form and a sodium polysulfide, introducing the padded material, without intermediate drying, into a dwelling chamber wherein the material is subjected to a hot air treatment for a period of from 1 to 10 minutes at a temperature in the range of from 80 to 980C or for a period of from 10 to 60 seconds at a temperature in the range of from 110 to 2200C, removing the material from the dwelling chamber and subsequently subjecting the material to a reoxidation treatment to form the disulfide form of the sulfur dyestuff.

2. A process as claimed in claim 1, wherein a web-like structure is dyed.

3. A process as claimed in claim 2, wherein slubbings, card slivers or tow are dyed.

4. A process as claimed in any one of claims 1 to 3, wherein the sodium polysulfide has the formula Na2Sx, where x, on average, is a number from 2 to 5.

5. A process as claimed in any one of claims 1 to 4, wherein the aqueous dyestuff liquor contains the sodium polysulfide in an amount of from 15 to 25 cubic centimetres of a 15% strength aqueous sodium polysulfide solution per litre of liquor.

6. A process as claimed in any one of claims 1 to 5, wherein the material is subjected to the hot air treatment in the dwelling chamber while in a pleated state.

7. A process as claimed in any one of claims 1 to 6, wherein the hot air treatment at a temperature of from 80 to 980C is carried

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. washing installation. Uniform deeply olive-coloured slubbings were obtained. Example 2 Viscose staple sliver was dyed on a continuous thermosol installation (normally used for dyeing slubbings of synthetic fibres, for example polyester fibres) consisting of a padder, perforated drum dryer, perforated drum thermosol device and after-treatment unit. For this process the temperatures in the dryer and in the thermosol installation were lowered to 900C. The fresh air feed was reduced to about 5%. The air circulation conditions were not reduced or were only slightly reduced, in order to ensure the reliable feed of the slubbings. The slubbings were padded, at a liquor pick-up of 90% (calculated on the weight of the dry goods), with an aqueous padding liquor having a temperature of 20"C and consisting of 45 g/l of Sulfur Brown 10 (C.I. No. 53,005), 30 g/l of Sulfur Red 6 (C.I. No. 53,720) and 25 g/l of Sulphur Brown 16 (C.I. No. 53, 285) which had been dissolved by having poured over them a hot aqueous solution of 80 g/l of sodium sulfide (technical grade, crystalline) in an amount which was about 1/10 of the total amount of liquor required. This solution was mixed with the remaining 9/10 of the amount of liquor, consisting of cold water, and 25 g/l of a 15% strength aqueous sodium polysulfide solution CNa2Sx; x = 2 to 5) were also added. The padded slubbings were fed continuously into the installation as described above, through which they passed in 3 minutes. After leaving the thermosol unit the goods were after-treated as described in Example 1. A strong, level brown dyeing of the viscose staple slivers was obtained. Example 3 Card slivers made of cotton were dyed in an installation according to Figure 3 of German Offenlegungsschrift No. 2,406,257 with an aqueous padding liquor which consisted of: 35 g/l of Solubilized Sulfur Green 9 (C.I. No. 53,006), 10 g/l of Solubilized Sulfur Brown 60 (C.I. No. 53,326), 120 cm3/l of a 20% strength aqueous solution of sodium bisulfide, 15 cm/lofa 15% strength aqueous solution of a sodium polysulfide (Na2Sx; x = 2 to 5), 20 g/l of calcined sodium carbonate and 3 g/l of a wetting agent based on an alkanesulfonate. The material was padded continuously at room temperature and at a liquor pick-up of 100% (calculated on the weight of the dry goods), and the padded slivers were placed in the installation at an air temperature of 95"C. After a dwelling time of 8 minutes, the slivers were removed, again continuously, from the installation and after-treated as described in Example 1. A uniform, strong olive dyeing was obtained. Example 4 An aqueous padding liquor was prepared from 60 g/l of Solubilized Sulfur Blue 7 (C.I. No. 53,441), 6 g/l of Solubilized Sulfur Brown 16 (C.I. No. 53,286), 80 g/l of sodium sulfide (technical grade, crystalline), 15 cm3/l of a 15% strength solution of a sodium polysulfide (Na2Sx; x = 2 to 5) and 3 g/l of an anionic wetting agent based on an alkanesulfonate, and a non-woven fabric made of cotton was padded to give a liquor pick-up of 80% (calculated on the weight of the dry goods). The padded non-woven fabric was fed to a perforated drum unit and treated in this with hot air at 1800C for 30 seconds. In the hot air section of this unit, only the feed of fresh air was moderated to 10%. Thereafter, the non-woven fabric was subjected to an after-treatment as described in Example 1. A deep, uniform navy blue dyeing was obtained. WHAT WE CLAIM IS:

1. A continuous process for dyeing a fibre material comprising cellulose fibres or a mixture of cellulose and synthetic fibres, which comprises padding the material with an aqueous liquor, at room temperature, containing a sulfur dyestuff (as hereinbefore defined) in the reduced form and a sodium polysulfide, introducing the padded material, without intermediate drying, into a dwelling chamber wherein the material is subjected to a hot air treatment for a period of from 1 to 10 minutes at a temperature in the range of from 80 to 980C or for a period of from 10 to 60 seconds at a temperature in the range of from 110 to 2200C, removing the material from the dwelling chamber and subsequently subjecting the material to a reoxidation treatment to form the disulfide form of the sulfur dyestuff.

2. A process as claimed in claim 1, wherein a web-like structure is dyed.

out for a period of from 3 to 7 minutes.

8. A process as claimed in any one of claims 1 to 7, wherein the padding liquor contains one or more fixation auxiliaries.

9. A process as claimed in claim 1, conducted substantially as described herein.

10. A process as claimed in claim 1, conducted substantially as described in any one of the Examples.

11. A fibre material comprising cellulose fibres or a mixture of cellulose and synthetic fibres, whenever dyed by a process as claimed in any one of claims 1 to 10.

12. Slubbings, card slivers or tow comprising cellulose fibres or a mixture of cellulose and synthetic fibres, whenever dyed by a process as claimed in any one of claims 1 to 10.