|Title of Invention||
A METHOD OF DYEING TEXTILE WEBS OF POLYESTER FIBRES OR MIXTURES OF POLYESTER FIBRES AND OTHER FIBRES,AND A CORRESPONDING JIGGER
|Abstract||The present invention relates to a method of dyeing textile webs of polyester fibres (PES fibres) or mixtures of PES fibres and other fibres in a dyeing bath in a jigger, wherein the textile web is unwound from a roll in the jigger and conveyed through the dyeing bath and then wound on to the other roll in the jigger, the direction of winding being reversible after the length of textile web has run through, and wherein dyeing is effected under atmospheric pressure, without access of air or exchange with the ambient .atmosphere, in such manner that the dyeing bath is kept at the boiling point of the dyeing liquor or at a temperature slightly below the boiling point, characterized in that the textile web is additionally heated, at least immediately before running on to the roll on which it is being wound.|
The invention relates to a method and a jigger for dyeing textile webs of polyester (PES) fibres or mixtures of PES fibres and other natural fibres, more particularly cellulose fibres such as cotton, linen, wool or the like and synthetic fibres such as viscose fibres, wherein a web of material is unwound from a roll, conveyed through a dyeing bath and then wound to form a roll and the process is repeated after each reversal of motion of the web.
Polyester fibres are much more difficult to dye than other conventional textile fibres. This is because of their closed structure and high degree of orientation, which results in low swelling capacity and in water-repellent properties. In addition, the polyester fibre does not contain any free dye-bonding groups and has only slightly affinity for water-soluble dyes.
With few exceptions, polyester fibres can be dyed only with dispersion dyes, which can be used on polyester textiles by the following three basic methods:
1) Dyeing at temperatures up to 100°C on machines operating at atmospheric pressure, using special aids or "carriers";
2) Dyeing at temperatures between 120°0 and 130°C on "HT" dyeing machines operating at elevated pressure and
3) Thermosol methods wherein the dye applied to the material is fixed by dry heat at a temperature range from 190° to 220°C.
The thermosol method mentioned in 3) is disadvantageous owing to the relatively low liquor pick-up of about 35% when dyeing textile webs containing up to 100% polyester fibres. More particularly the dye pick-up is insufficiently uniform. In addition, the thermosol method, like all continuous processes, is economic only for dyeing large batches.
Dyeing with carriers as per 1) was frequently used, particularly in the first phase of introduction of polyester fibres into textile production. Nowadays it is much less used. Carriers allow PES fibres to swell adequately at temperatures as low as 95°C, thus promoting the diffusion of dyes into the PES fibres. However, carriers are usually toxic and their use is inconsistent with protection of the environment.
The main method of extractive dyeing therefore is HT dyeing at 120°C to 130°C. However dyeing at temperatures above 100°C is possible only on installations designed for an excess pressure corresponding to the stated temperature range.
For example it is known to use an "HT" jigger for dyeing of PES fibres with dispersion dyes, enabling dyeing to be carried out at a temperature of 120°C to 130°C. To this end, the jigger casing must withstand a vapour pressure of 2 to 5 bar. This complicates the construction and operation of a plant of this kind.
The object of tne invention therefore is to improve the dyeing of textile webs of polyester and mixtures thereof.
This problem is solved by a proposed method having the features in claim 1.
One critical factor when dyeing PES is the dyeing temperature. In dyeing machines which operate without pressure (at atmospheric pressure), the liquor cannot be raised above the boiling temperature, which as is known depends on the height above sea level. At a height above sea level of about 300 metres, the maximum temperature attainable in closed dyeing vessels is about 98°C to 99°C, even if the space inside the jigger hood is perfectly sealed.
According to the invention, the textile web after leaving the dyeing bath, which is at or immediately below boiling point, is heated and brought to the saturated steam temperature of 100°C and is wound up under these operating conditions. (The temperature is so to speak incorporated in the winding and assists the winding-up process). A temperature gain of only a few degrees results in an appreciable increase of several percent in the dye yield. The inventive step ensures the maximum temperature increase possible at atmospheric pressure, and is used to improve the result of the process. By means of the invention, textile webs containing polyester fibres can be dyed with good colour depth and colour fastness in apparatus requiring a comparatively simple and not pressure-resistant casing and with comparatively low use of energy.
without need for a large number of passes of material through the dyeing bath.
The additional heating according to the invention is advantageously provided by blowing saturated steam (claim 2).
The efficiency of dyeing according to the invention is increased by a suitable choice of dye. Use is made of dispersion dyes which diffuse into and dye the polyester fibres under the stated conditions, i.e. at temperatures of about 100°C. The selection is also determined by fulfilment of the following criteria:
a) Dye yield under atmospheric pressure at least 65% or more at 2% dyeing, i.e. weight of dye in the liquor = 2% weight of material-
b) Light-fastness at the same depth of colour is at least 5 (DIN 54004).
c) Washing fastness at 60°C at least 4/4-5/4-5 (DIN 54010) -
d) Fastness in reducing medium.
The following types of dispersion dyes have been found particularly advantageous in this respect for dyeing textile webs of PES fibres by the method according to the invention (claim 3):
Colour Index Disperse Yellow 3
e.g. Cellintongelb G (BASF)
Colour Index Disperse Yellow 60 e.g. Resolingelb RL (Bayer)
Colour Index Disperse Yellow 68
e-g, Samarongoldgelb HGL (Hoechst)
Colour Index Disperse Orange 3
e.g. Cellitonorange GR (BASF)
Colour Index Disperse Red 1
e.g. Cibacetscharlach 2B (Ciba-Geigy)
Colour Index Disperse Red 50
e.g. Resolinscharlach RR (Bayer)
Colour Index Disperse Violet 1
e.g. Cibacetviolett 2R (Ciba-Geigy)
Colour Index Disperse Blue 81
e.g. Resolinblau GRL (Bayer)
These dyes, in the widest sense, are "small-molecular" dispersion dyes, i.e. "low-energy" types with high migration capacity, i.e. requiring little energy for penetrating into the fibres and having acceptable fastness on sublimation. The same applies, with some restrictions, to "medium-molecular" dispersion dyes, i.e. "medium-energy" types with adequate migration capacity and very good fastness on sublimation. Large molecular dispersion dyes or "high-energy" types with low migration capacity and maximum fastness on sublimation are usually less suitable or unsuitable.
The said dispersion dyes meet the previously-mentioned criteria. They can also be used for trichromatic dyeing to the required extent, and also have sufficient fastness on sublimation. The said types of dyes are more efficient, particularly in combination with the additional heating, i.e. at higher dyeing temperatures.
Another important factor improving the efficiency of dyeing by the method according to the invention is the liquor ratio or concentration gradient. The concentration gradient influences the diffusion of dye into the fibres.
According to claim 4 the dyeing liquor ratio should be from 1 : 1,3 to 1 : 2.5. This doubles the concentration of dye in the liquor compared with conventional jiggers. The same factor has a very marked effect on the dye yield.
One exemplfied embodiment of the invention will now be explained in detail with reference to a drawing of a two-tank jigger of the kind in question. The drawing is a perspective view, partly diagrammatic and in section, of a jigger having known basic components.
The jigger comprises two winding rollers 21, 22 in a casing 10, between which a textile web 1 of PES fibres is wound and unwound and between which two small tanks 11, 12 are disposed, for alternate or successive use during the same run, a vertically adjustable width-adjusting and spreading tube 13 being disposed between the tanks. Rollers 14, 15 for pressing with adjustable force against the winding rollers 21, 22 are provided
ana designed to improve the neatness of the rolls- The casing 10 is suitably and efficiently sealed against penetration of or exchange with external air. It has a pivotable hatch 16 for batch-changing.
An automatic control system 17 associated with temperature sensors (not shown separately in the drawing) keeps the dyeing liquors 2, 3 in the tanks 11, 12, by means of heating registers 4, at a temperature equal to or only slightly, e.g. 1%°C below the boiling point of the dye liquors at the prevailing atmospheric pressure.
Steam-spraying tubes 18, 19 carrying saturated steam and provided with nozzles along their length are disposed in the space above the dyeing tanks 11, 12 (optionally only one of which is used) in such manner that the textile web 1 is sprayed over its entire width with saturated steam 24 in that region of the winding roller on which the textile web 1 of PES fibres has just been wound (i.e. roller 22 in the drawing). The steam-spraying tubes 18 are disposed immediately in front of the place where the textile web 1 runs on to the roll and act on the corresponding side of the textile web 1, which faces them when the roll is being wound, so that it runs on to the roll immediately after its temperature has been raised by a few degrees. The steam-spraying tubes 19 act on the outer periphery of the roll. The spraying raises the temperature to the saturated steam temperature, at least in that area of the web 1 which is running on to the roll, and at the periphery of the roll. Of course, spraying of saturated steam can advantageously be continued when
The PES textile web ±s unwound from the corresponding roll (from roller 21 in the drawing).
In principle, other methods can be used for additionally heating the textile web 1. As before, heating is controlled by the automatic control unit 17, using suitable measuring devices.
It has been found very advantageous to add "film-forming agents" to the dyeing liquor for PES fibres in tanks 11 and 12. Film-forming agents based on acrylamide polymers increased the liquor pick-up by 10%. The increased amount of liquor was particularly advantageous inside the roll of material, because the dye supply during the residence time on the roll was greater and the dye diffusion was accelerated. Dyeing was also found to be more uniform. As little as 3 to 5 g of an acrylamide polymer-based film-forming agent per litre of dyeing liquor was sufficient.
The following test dyeing operations were performed on the jigger as described;
Material: Decorative material containing 100%
PES (pre-washed), 1200 m, 246.4 kg
Dyeing liquor: 400 litres
Liquor ratio: 1 : 1.62
Passage 1,2 Metering of dye 70°C 70°C
3-8 Dyeing 99°C 100°C
9 Hot rinsing 80°C 80°C
10 ... 60°C 60°C
11 ... 40°C 40°C
12 Cold rinsing 20°C 20°C Speed: Dyeing 100 m/min
Rinsing 140 m/min
!• A method of dyeing textile webs of polyester fibres (PES fibres) or mixtures of PES fibres and other fibres in a dyeing bath in a jigger,
wherein the textile web is unwound from a roll in the jigger and conveyed through the dyeing bath and then wound on to the other roll in the jigger, the direction of winding being reversible after the length of textile web has run through, and
wherein dyeing is effected under atmospheric pressure, without access of air or exchange with the ambient atmosphere, in such manner that the dyeing bath is kept at the boiling point of the dyeing liquor or at a temperature slightly below the boiling point,
characterised in that
the textile web is additionally heated, at least immediately before running on to the roll on which it is being wound.
2. A method of dyeing according to claim 1, characterised in that heating is effected by blowing saturated steam on to the textile web in the winding gap.
3. A method of dyeing according to claim 1 or 2, characterised in that one or more of the following types of dye are supplied to the dyeing bath:
Colour Index Disperse Yellow 3 Colour Index Disperse Yellow 60 Colour Index Disperse Yellow 68 Colour Index Disperse Orange 3 Colour Index Disperse Red 1 Colour Index Disperse Red 50 Colour Index Disperse Violet 1 Colour Index Disperse Blue 81
4. A method of dyeing according to any of claims 1 to
3, characterised in that the liquor ratio is 1 : 1 • 3 to
1 : 2.5-
5- A method of dyeing according to any of claims 1 to
4, characterised in that a film-forming agent which
increases the liquor pick-up capacity on to the textile
web of PES fibres is added to the dyeing liquor-
6- A method of dyeing according to any of claims 1 to
5, characterised in that by a film-forming agent based
on acrylamide polymers.
7- A jigger for working the method according to any
of claims 1 to 6, comprising
a casing (10) which is accessible for changing of batches but is otherwise sealed,
two rollers (21, 22) rotatably mounted in the casing (10) and alternately drivable and between which the textile web (1) can be wound and unwound.
at least one dyeing bath through which the textile web (1) is conveyed during the winding process, and
a heating device (17, 4) for heating the liquor bath at the boiling point of the dyeing liquor (2, 3) or at a temperature immediately below the boiling point under substantially atmospheric pressure inside the casing (10), characterised by an additional heating device which acts on the textile web (1) immediately before it runs on to the roll on to which it is being wound and which subjects the textile web to the temperature of saturated steam.
8, A jigger according to claim 7, characterised in
that the heating device has steam-spraying tubes (18,
19) Which operate across the width of the textile web
(1) and can be supplied with saturated steam.
9, A jigger according to claim 8, characterised in
that the steam-spraying tubes (18) are disposed on the
side for lapping the textile web (1)
10, A jigger according to any of claims 7 to 9,
characterised in that it is of the two-tank kind.
11, A method of dyeing textile webs of polyester fibres
substantially as herein described with reference to the
|Indian Patent Application Number||1498/MAS/1996|
|PG Journal Number||26/2007|
|Date of Filing||26-Aug-1996|
|Name of Patentee||EDUARD KUSTERS MASCHINENFABRIK GMBH & CO.KG|
|Applicant Address||GLADBACHER STRASSE 457 D-47805 KREFELD|
|PCT International Classification Number||D06B001/02|
|PCT International Application Number||N/A|
|PCT International Filing date|