GB1590064A

GB1590064A - Process for the dyeing of textiles in rope form

Info

Publication number: GB1590064A
Application number: GB18978/78A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1977-05-13
Filing date: 1978-05-11
Publication date: 1981-05-28
Also published as: IT1094747B; JPS6114271B2; DE2721680B2; DE2721680C3; JPS53139877A; FR2390533B1; ES469557A1; BE867114A; DE2721680A1; FR2390533A1; CH622148GA3; IT7823303A0; PT68027A; PT68027B

Abstract

Textile goods in hank form comprising natural or synthetic fibres or comprising blends of such fibres are dyed in jet or overflow dyeing units. The textile goods are deaerated by steaming in a dyeing container and heated up by means of the steam to approximately dyeing temperature. The entire dyeing liquor is rapidly poured into the closed and steam-filled dyeing container at approximately dyeing temperature and with the aid of excess pressure acting on the liquor and brought into contact with the textile goods. The hot dyeing liquor introduced under pressure into the closed dyeing container in some cases takes over the transport of the textile goods in the course of the filling phase. The dyeing process is carried out by recycling the liquor and circulation of the goods at the respective steam pressure of the heated dyeing liquor under isothermal conditions. The novel process enables a reduction in the dyeing time in jet or overflow units, together with achievement of an even dyeing appearance, by at least a half, relative to the dyeing times of previously known jet and overflow dyeing processes.

Description

(54) PROCESS FOR THE DYEING OF TEXTILES IN ROPE FORM (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: This invention relates to a process for dyeing textile materials in rope form.

For dyeing textile ropes on jet or overflow dyeing apparatus, the textile material is conventionally passed into the dyeing apparatus containing the dye liquor, with the result that isothermal dyeing is not generally possible (see, for example "Möglichkeiten und Zielsetzung der Jet-Färberei", published in Melliand Textilberichte 52 (1971), pp. 216-220 and 318-323). Various attempts have been made to reduce the length of the dyeing cycle, for example by increasing the speed of rotation of the textile rope and the rate of the circulation of the dyeing liquor by reducing the goods-to-liquor ratio and by usir.g more powerful pumps.However, none has succeeded in attaining the conventional dyeing cycles used for package dyeing, and periods of at least 3 hours are still required for this operation.

The present invention seeks to provide a process for the isothermal dyeing of textile rope materials in jet or overflow dyeing apparatus, in which the dyeing cycles hitherto required by conventional methods because of the long heating times for the liquor and the textile material, can be considerably reduced.

The present invention now provides a process for dyeing textile materials of natural and/or synthetic fibers in rope form with dyeing liquors containing thermofixable dyestuffs in a jet or overflow dyeing apparatus, which comprises the steps of (i) deaerating the textile rope with steam; (ii) heating the textile rope to substantially the dyeing temperature with steam in the closed dyeing vessel; (iii) forcing the dyeing liquor at substantially the dyeing temperature into the closed dyeing vessel by means of a relative excess pressure applied thereto, to cause at least partial circulation of the textile rope; and (iv) dyeing the textile rope by circulating the dyeing liquor and circulating the textile rope under substantially isothermal conditions under at least autogenous pressure.

In accordance with the present invention, therefore, the fibrous material to be dyed is first freed from air by steaming in the dyeing vessel and then, after the vessel has been closed to the external atmosphere, heated to about the dyeing temperature by means of steam. Subsequently, the dyeing liquor at about the dyeing temperature is forced rapidly with the aid of relative excess pressure into the closed dyeing vessel containing steam and the textile material. The dyeing process itself may then be carried out under isothermal conditions by circulation of the dyeing liquor and circulation of the textile material under the pressure developed in the vessel by the hot dyeing liquor. It is important that the hot dyeing liquor is fed under pressure into the closed dyeing vessel in such a manner as to cause at least partially the transport of the textile material.This process, applied on jet or overflow dyeing apparatus, reduces the dyeing time to at most one half of that of hitherto known processes, although still yielding level dyeings.

The initial deaeration step of the process of the present invention, during which the apparatus is open to the external atmosphere may be combined with a pretreatment step, in which the textile material is subjected to water having a temperature below the dyeing temperature, for example at 80 to 900 C, and to which the necessary auxiliaries, especially wetting agents have been added, for example, immediately upstream of the spray nozzle by injection or via pressure tubing.After the textile material has been introduced and subjected to several circulation cycles in the pretreatment liquor, the latter is drained off (and may be collected for reuse); this will generally cause the temperature to drop to about 60 to 700 C. Subsequently, steam is blown into the vessel and the vessel is sealed, causing further heating of the textile material to about 1000C.

In the next step of the dyeing process, the hot dyeing liquor is fed into the dyeing vessel. The dyeing liquor may be stored in a separate pressure reservoir, but is preferably formed as required by adding dyestuff upstream of the inlet to the dyeing vessel, to hot water from a central pressure reservoir. It is of no significance whether the dyestuff, and any associated auxiliaries and pH control agents are added to liquor in the reservoir or while passing the liquor to the dyeing vessel. In the latter case, however, it is possible to vary the concentration of the dyestuff and/or auxiliaries and/or pH control agent in the dyeing liquor during the operation of charging the dyeing vessel with the dyeing liquor, so that for example, the dyestuff concentration may be initially low and gradually increased.This applies also to any dyeing auxiliaries which may be used, although in this case it may be preferred for the auxiliaries to be in a higher concentration initially so that a substantial amount of dispersing agent and any other auxiliaries, such as antifoaming agents and crease inhibitors are present in the dyeing vessel at the beginning of this step.

The temperature of the dyeing liquor will naturally depend on the type of and types of fibers to be dyed and on the particular dyestuffs used, while maintaining isothermal dyeing conditions. The temperature is preferably about 1000C when dyeing ropes of wool, polyamide and polyacrylonitrile fibers, and about 120 to 1350C when dyeing ropes of polyester fibers. The dyeing temperature may also preferably be 1000C in the case of copolymers, and in the case of cellulose fibers to be dyed with direct dyestuffs. When reactive dyestuffs are used, the dyeing temperature may be from 90 to 1000C, depending on the nature of the reactive group(s) and the type and/or concentration of alkali. Control of the temperature of the dyeing liquor is especially useful for sensitive textile materials and for controlling their shrinkage behaviour.

If desired, circulation of the dyeing liquor, for example by means of a circulation pump, may be initiated before all the dyeing liquor has been added to the dyeing vessel.

The dyeing process of the present invention is suitably carried out in any type of jet or overflow dyeing apparatus, or in a partially flooded apparatus, and the dyeing liquor in the dyeing vessel may be under an atmosphere of compressed air.

The process of the present invention has the surprising and unexpected advantage that, despite the considerably different sequence of steps and periods of time involved compared to known processes, level dyeings are obtained in a considerably reduced dyeing time. The process also has the advantage that the individual steps follow one another in an uninterrupted sequence. Thus, for example, the textile material is placed in the open dyeing vessel which already contains the pretreatment liquor. Immediately after this liquor has been drained off, a pressure is established in the vessel by introducing steam. The textile material is thereby steamed and heated, and shrinkage starts.

The hot dyeing liquor containing the dyestuff and for example, auxiliaries and pH control agent is then introduced into the dyeing vessel containing the preheated textile material, preferably by means of a nozzle or nozzle system.

During the dyeing operation, that is, the absorption of the dyestuffs, the dyeing liquor is circulated by means of a circulation pump, preferably one having a high conveying capacity, and the textile material is transported by means of a winch and/or a jet or flow device. The circulation speed of the dyeing liquor and the circulation speed of the textile material is higher than hitherto usual, and very rapid temperature control can be ensured simply by heat exchangers in the circulating dyeing liquor cycle. Any necessary additional components of the dyeing liquor may be introduced during this step via the circulation system or by injection to the vessel by means of a force pump.

The following Example illustrates the invention.

EXAMPLE: In a jet dyeing apparatus of known design, an aqueous pretreatment liquor having a temperature of 900C and containing a commercial wetting agent is contacted for 5 minutes with a knitted fabric in rope form made from texturized polyester fiber material; during this pretreatment step, the textile rope is rotated and the liquor is simultaneously circulated. The pretreatment liquor is drained off and the textile material is presteamed by introducing saturated steam at 1000C, and the apparatus is closed to the external atmsophere.After a total pretreatment period of 15 minutes, an aqueous dyeing liquor having a temperature of about 1000C and a pH of about 4.5 and containing in dispersion, relative to the weight of the textiles material, 0.3% of a disperse dyestuff consisting of a mixture (about equal amounts) of the compounds of the formulae

is fed to the apparatus against the vapour pressure (condensation) therein.

After heating the vessel to the dyeing temperature during which the dyeing liquor is rapidly circulated, the circulating rope-shaped textile material is dyed for 20 minutes at 1300C and a textile-to-liquor ratio of 1: 6.5, and then allowed to cool for 30 minutes. After cooling to 80 C, this temperature is maintained for a further 10 minutes. After a total dyeing time of 90 minutes, including the liquor charging step, the dyed textile rope is subjected to conventional after-treatment. A completely level blue dyeing of the knitted fabric is obtained.

In the case of less sensitive textile materials, the cooling phase may be reduced by 15 to 20 minutes.

As compared to known processes in jet dyeing apparatus, the process of the present invention carried out on an industrial scale results in a time saving of 40 to 60 minutes.

WHAT WE CLAIM IS: 1. A process for dyeing a textile material of natural and/or synthetic fibers in rope form with a dyeing liquor containing a thermofixable dyestuff in a jet or overflow dyeing apparatus, which comprises the steps of (i) deaerating the textile rope with steam; (ii) heating the textile rope to substantially the dyeing temperature with steam in the closed dyeing vessel; (iii) forcing the dyeing liquor at substantially the dyeing temperature into the closed dyeing vessel by means of a relative excess pressure applied thereto, to cause at least partial circulation of the textile rope; and (iv) dyeing the textile rope by circulating the dyeing liquor and circulating the textile rope under substantially isothermal conditions under at least autogenous pressure.

2. A process as claimed in claim 1, wherein, prior to step (i), the textile material is pretreated under atmospheric pressure at a temperature below the dyeing temperature with an aqueous liquor containing a wetting agent.

3. A process as claimed in claim 1 or claim 2, wherein the hot dyeing liquor is prepared in a separate pressure reservoir and contains the dyestuff, one or more dyeing auxiliaries and, optionally, one or more pH control agents, and is fed directly under pressure to the dyeing vessel.

4. A process as claimed in claim 1 or claim 2, wherein the dyestuff, one or more dyeing auxiliaries and, optionally, one or more pH control agents are added to hot water flowing from a pressure reservoir, and the resulting dyeing liquor is fed under pressure to the dyeing vessel.

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

Claims

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

EXAMPLE: In a jet dyeing apparatus of known design, an aqueous pretreatment liquor having a temperature of 900C and containing a commercial wetting agent is contacted for 5 minutes with a knitted fabric in rope form made from texturized polyester fiber material; during this pretreatment step, the textile rope is rotated and the liquor is simultaneously circulated. The pretreatment liquor is drained off and the textile material is presteamed by introducing saturated steam at 1000C, and the apparatus is closed to the external atmsophere.After a total pretreatment period of 15 minutes, an aqueous dyeing liquor having a temperature of about 1000C and a pH of about 4.5 and containing in dispersion, relative to the weight of the textiles material, 0.3% of a disperse dyestuff consisting of a mixture (about equal amounts) of the compounds of the formulae

is fed to the apparatus against the vapour pressure (condensation) therein.

After heating the vessel to the dyeing temperature during which the dyeing liquor is rapidly circulated, the circulating rope-shaped textile material is dyed for 20 minutes at 1300C and a textile-to-liquor ratio of 1: 6.5, and then allowed to cool for 30 minutes. After cooling to 80 C, this temperature is maintained for a further

10 minutes. After a total dyeing time of 90 minutes, including the liquor charging step, the dyed textile rope is subjected to conventional after-treatment. A completely level blue dyeing of the knitted fabric is obtained.

In the case of less sensitive textile materials, the cooling phase may be reduced by 15 to 20 minutes.

As compared to known processes in jet dyeing apparatus, the process of the present invention carried out on an industrial scale results in a time saving of 40 to 60 minutes.

WHAT WE CLAIM IS: 1. A process for dyeing a textile material of natural and/or synthetic fibers in rope form with a dyeing liquor containing a thermofixable dyestuff in a jet or overflow dyeing apparatus, which comprises the steps of (i) deaerating the textile rope with steam; (ii) heating the textile rope to substantially the dyeing temperature with steam in the closed dyeing vessel; (iii) forcing the dyeing liquor at substantially the dyeing temperature into the closed dyeing vessel by means of a relative excess pressure applied thereto, to cause at least partial circulation of the textile rope; and (iv) dyeing the textile rope by circulating the dyeing liquor and circulating the textile rope under substantially isothermal conditions under at least autogenous pressure.
2. A process as claimed in claim 1, wherein, prior to step (i), the textile material is pretreated under atmospheric pressure at a temperature below the dyeing temperature with an aqueous liquor containing a wetting agent.
3. A process as claimed in claim 1 or claim 2, wherein the hot dyeing liquor is prepared in a separate pressure reservoir and contains the dyestuff, one or more dyeing auxiliaries and, optionally, one or more pH control agents, and is fed directly under pressure to the dyeing vessel.
4. A process as claimed in claim 1 or claim 2, wherein the dyestuff, one or more dyeing auxiliaries and, optionally, one or more pH control agents are added to hot water flowing from a pressure reservoir, and the resulting dyeing liquor is fed under pressure to the dyeing vessel.
5. A process as claimed in claim 4, wherein the concentration of dyestuff and/or

dyeing auxiliaries and/or pH control agents is varied during the course of addition of the dyeing liquor to the dyeing vessel.
6. A process as claimed in claim 1, carried out substantially as described in the Example herein.
7. A textile material of natural and/or synthetic fibers which has been dyed by a process as claimed in any of claims 1 to 6.