WO2020234897A1

WO2020234897A1 - Process for dyeing yarns and system thereof

Info

Publication number: WO2020234897A1
Application number: PCT/IN2020/050444
Authority: WO
Inventors: Debasish Halder; Punit Lalbhai; Rahul Roy
Original assignee: Arvind Limited
Priority date: 2019-05-17
Filing date: 2020-05-16
Publication date: 2020-11-26

Abstract

The present invention discloses a process for dyeing yarns with oxidative dyes comprising steps of preparing a sheet of yarns to be dyed, foam dyeing the sheet of yarns with oxidative dye, passing the dyed yarns through stabilizing unit having a combination of gases including reactive and non-reactive gas for penetrating the dye into the foam dyed yarns, fixing and thereafter drying the dyed yarns. The dyed yarn may follow steps of washing, drying, sizing, drying and preparing weavers beam of the dyed yarn.

Description

PROCESS FOR DYEING YARNS AND SYSTEM THEREOF

TECHNICAL FIELD OF THE INVENTION

[1] The present invention relates to a process and a system for dyeing yarns. The dyed yarns are used for manufacturing denim fabrics and garments made from said fabrics.

BACKGROUND OF THE INVENTION

[2] A denim fabric is generally defined as a woven fabric having dyed warp and undyed weft yarns interlaced to each other. Mainly, warp yams are dyed with oxidative dyes including indigo dye, sulphur dye or a combination of dyes i.e. indigo with sulphur dye. The significance of denim fabric is, that the fabric has fading characteristics.

[3] Presently, slasher dyeing, and rope dyeing techniques are mainly used for yarn dyeing of denim fabric.

[4] In slasher dyeing, yarns are dyed in sheet form. Accordingly, yams are pre-wetted and followed by a dyeing process. Usually dyeing is carried out by using 6 - 8 dye baths. However, number of dye baths depends on shade requirement of the fabric. It is understood herein that a greater number of dye baths required for darker shade and a smaller number of dye baths are required for lighter shade. Every dye bath is followed by an aeration unit for enhancement of dye fixation into the yarn. After dyeing, dyed yarns are passed through washing unit to remove unfixed dyes from the dyed yarn which is followed by drying process. Partially dried yarns are passed through sizing process. [5] In rope dyeing, yarns are converted into the rope form. At a time, 6-60 ropes are dyed. The ropes are pre-wetted and followed by dyeing process. Each dye bath is followed by aeration unit. Generally, eight number of dye baths are used. The dyed yams are washed to remove excess dye from yarn which is followed by drying process. The dried yarns are collected in rope form in individual can and separated at re-beaming process, in this process dyed yams are converted into warper beam. These beams are used at sizing process, as per required number of yarns, the warper beams are combined together and converted into weaver’s beam. Sizing is a process which improves weavability of yam, followed by drying process, these yams are wound on to the weaver’s beam.

[6] In both the existing processes, the water and chemical consumption is more as well as total yarn passage length is also more in each dyeing machine. Further, water consumption for dyeing yam by these processes is approx. 5 - 15 lit/meter of warp sheet. Moreover, the waste/coloured water leaving the dyeing process requires to be treated before disposal into eco-system.

[7] Therefore, there is a need of a yam dyeing process and system which will solve at least one of the problems as discussed above.

SUMMARY OF THE INVENTION

[8] Accordingly, an aspect of the present invention discloses a process for dyeing yarns, the process comprising the steps of: preparing a sheet of yams; passing the sheet of yams through a first foam dyeing unit of a dyeing system for continuously foam dyeing the yams with a class of dye having fading characteristics; passing the foam dyed yams through a first stabilizing unit of the dyeing system for fixing dye onto the yams about a predetermined time; drying the foam dyed yarns in a first drying unit of the dyeing system at a predetermined temperature; sizing the dyed yarns in a sizing unit of the dyeing system; drying the sized yarns in a second drying unit of the dyeing system at said predetermined temperature; and passing the dyed yams through an accumulator of the dyeing system for wounding onto a weaver’s beam for weaving the dyed yarns.

[9] According to another aspect, the present invention discloses a system for dyeing yams, the system comprising: a first foam dyeing unit for dyeing a sheet of yarns; a first stabilizing unit having a closed chamber with a combination of gases including reactive and non-reactive gas that includes nitrogen and helium for penetrating the dye into the foam dyed yarns and for fixing the dye; a first drying unit for drying the dyed yarns at a predetermined temperature; a sizing unit having a size box configured to spray a desired size through nozzles uniformly on sheet of yarns; a second drying unit for drying the sized yams at said predetermined temperature; and an accumulator for accumulating the dyed yarns onto a weaver’s beam for weaving the dyed yams as plurality of warp yarns for manufacturing denim fabrics.

[10] According to still another aspect, the present invention discloses a fabric comprising a plurality of warp yarns and a plurality of weft yarns including spun yarns, comprising stretch or non-stretch yarns or combination thereof selected from the group of natural fibres or regenerated fibres or recycled fibres, or blend of natural fibres and elastomeric fibres and/or man- made fibres or blend of natural fibres with synthetic fibres or blend of recycled fibre with natural fibre and/or regenerated fibre, wherein the warp yarns are foam dyed.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[11] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[12] Figure 1 illustrates a block diagram showing process for dyeing yams according to an aspect of the present invention; and

[13] Figure 2 illustrates a system for dyeing yams, according to another aspect of the present invention.

[14] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.

[15] Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. DETAILED DESCRIPTION OF THE INVENTION

[16] In general, the present invention claims a process for dyeing yarns with oxidative dyes comprising steps of preparing a sheet of yarns to be dyed, foam dyeing the sheet of yarns with oxidative dye, passing the dyed yams through stabilizing unit having a combination of gases including reactive and non-reactive gas for penetrating the dye into the yarns, fixing and thereafter drying the dyed yarns. The dyed yarn may follow steps of washing, drying, sizing, drying and preparing weavers beam of the dyed yarn.

[17] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

[18] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[19] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[20] Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged environment. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions in no way limit the scope of the invention.

[21] Referring Figures 1-2 shows a process (100), a system (200), a creel (205), a first foam dyeing unit (210), a first stabilization unit (215), a first drying unit (220), a sizing unit (225), a second drying unit (230), an accumulator (235), a weaver’s beam (240), one or more augmentation unit (250), a second foam dyeing unit (260), a second stabilizing unit (270), a washing unit (280) and a third drying unit (290).

[22] Referring Figure 1 illustrates a block diagram showing process (100) for dyeing yams. The process (100) comprises the steps of: step (105): preparing a sheet of yarns; step (110): passing the sheet of yams through a first foam dyeing unit (210) of a dyeing system (200) for continuously foam dyeing the yarns with a dye composition having fading characteristics. According to the embodiment, foam dyeing takes place at room temperature. The process includes the step (115): passing the foam dyed yams through a first stabilizing unit (215) of the dyeing system (200) for fixing dye onto the yams about a predetermined time; step (120): drying the foam dyed yarns in a first drying unit (220) of the dyeing system (200) at a predetermined temperature; step (125): sizing the dyed yarns in a sizing unit (225) of the dyeing system (200); step (130): drying the sized yarns in a second drying unit (230) of the dyeing system (200) at said predetermined temperature; and step (135): passing the dyed yams through an accumulator (235) of the dyeing system (200) for wounding onto a weaver’s beam (240) for weaving the dyed yarns.

[23] According to an embodiment, the process (100) optionally after step (120) and before step (125) includes the steps of: step (140): passing the foam dyed yarn through one or more augmentation unit (250) each having a second foam dyeing unit (260) with a class of dye same or different with same or different color shades and intensities than the class of dye of the first foam dyeing unit (210) of the dyeing system (200) and a second stabilizing unit (270) for obtaining a desired/ predetermined darker shade or different shades of dyed yams; step (150): washing dyed yarns in a washing unit (280) of the dyeing system (200) for removal of unfixed dye from the yams; and step (160): partially drying the dyed yarns in a third drying unit (290) of the dyeing system (200) and passing the dyed yarns to sizing unit (225) for further processing. [24] According to the embodiment, the yarns for warps may be spun yarn. The yarns may be rigid or stretchable yarns selected from the group of the yarns comprising natural fibres, regenerated fibres or recycled fibres or elastomeric yam or blend of natural fibres with synthetic fibres, or blend of recycled fibre with natural and/or regenerated fibre or combination thereof. The stretchable yam includes polyolefin and polyurethane. In an exemplary embodiment of present invention, cotton yarn is used as warp yam.

[25] According to the embodiment, the predetermined temperature of the drying units depends on yarn moisture. The temperature ranges from about 80 “Celsius to 120 ° Celsius.

[26] According to the embodiment, the dye-composition includes an oxidative dye from about 0.5 %w/w to about 5%w/w, a foaming agent from about 1.5%w/w to about 3% w/w, a wetting agent from about 0.3 %w/w to about 1% w/w and remaining amount including of water.

[27] According to the embodiment, foam density of the foam is about 0.02 gm/cm³ to about 0.05 gm/cm³.

[28] According to the embodiment, the predetermined time for fixing the dye onto the yarns is at least 1.5 minutes.

[29] According to the embodiment, the oxidative dye includes but not limited to indigo, sulphur, vat dyes and the like. In an exemplary embodiment of present invention, Indigo dye is used for dyeing warp yarn.

[30] Referring Figure 2 shows a system (200) for dyeing yarns. The system (200) comprises a first foam dyeing unit (210) for application of foam dyeing onto sheet of yams; a first stabilizing unit (215) having a closed chamber with a combination of gases including reactive and non-reactive gas that include but not limited to nitrogen and helium for penetrating the dye into the foam dyed yarns and for fixing the dye onto the yarn; a first drying unit (220) for drying the dyed yarns at a predetermined temperature; a sizing unit (225) having a size box configured to spray a desired size through nozzles uniformly on sheet of yarns; a second drying unit (230) for drying the sized yarns at said predetermined temperature; and an accumulator (235) for accumulating the dyed yarns onto a weaver’s beam (240) for weaving the dyed yams as plurality of warp yarns for manufacturing denim fabrics.

[31] According to the embodiment, the system (200) optionally may include one or more augmentation unit (250) each having a second dyeing unit (260) and a second stabilizing unit (270) for obtaining a darker shade or different shades of dyed yams. The dyed yarns leaving the stabilization unit (215) are dyed with foam dyeing again in the augmentation unit (250) and in the stabilizing unit (260) the dye is onto the yarn. The system (200) includes a washing unit (280) for removal of unfixed dye from the yams; and a third drying unit (290) for partially drying the yams followed by sizing unit (225).

[32] According to the embodiment, the size box is designed in such a way that the size is sprayed through spray nozzles and the nozzle designed in such a way that size is applied uniformly on warp sheet.

[33] According to the embodiment, total passage length of yarn in the dyeing system (200) is 350 meters, wherein the stabilization unit (215) has yarn passage length of about 50-80 meters. Whereas, the total passage length of yarn of conventional dyeing system is about 450 meters, wherein stabilization occurs in presence of air having yarn passage length above 100 meters. Therefore, the dyeing system (200) is customized thereby optimizing the yarn passage.

[34] According to still another aspect, the present invention discloses a fabric comprising a plurality of warp yarns and a plurality of weft yarns including spun yarns, comprising stretch or non-stretch yarns or combination thereof selected from

the group of natural fibres or regenerated fibres or recycled fibres, or blend of natural fibres and elastomeric fibres and/or man- made fibres or blend of natural fibres with synthetic fibres or blend of recycled fibre with natural fibre and/or regenerated fibre, wherein the warp yarns are foam dyed.

[35] According to an exemplary embodiment, the fabric may be rigid or stretch having the warp and weft yarn count ranges from about 4s Ne - 60s Ne. More preferably, the count ranges from about 10s Ne - 40s Ne. The elastomeric yarn count ranges from about 40 denier to 105 denier.

[36] According to the exemplary embodiment, the weight of the fabric ranges from 1.5 oz. per square yards to 20 oz. per square yards. More preferably, fabric weight ranges from 6 oz. per square yards to 12 oz. per square yards.

[37] According to the exemplary embodiment, the fabric has colour fastness to rubbing about 3.5 - 4 in dry condition and about 1.5 - 2 in wet condition and a colour fastness to ozone about 4 - 4.5, when measured as per standard AATCC 8 method. [38] According to the exemplary embodiment, the fabric is woven in denim weaves including twill, satin, sateen, or dobby.

[39] According to the exemplary embodiment, a garment is made from said fabric.

[40] According to the present invention, the yam dyeing process and system of the present invention consume minimum amount of water, so the effluent load is minimized. The shade is brighter than conventional process, as well as with this method, darker shade or different shades may be easily produced. According to the present invention, the dyeing composition does not include conventionally used chemicals for oxidative dyeing process and therefore the shade of the dye is brighter. Further, the fabric manufactured by the system and process is laser friendly.

Example 1:

[41] A dyeing system for yarns having a machine speed of about 20 mt/min.

The dyeing system includes foam dyeing unit, wherein a dyeing composition of oxidative dye particularly Indigo is selected. The dyeing composition includes an Indigo dye from about 3% w/w, a foaming agent from about 1.5%w/w, a wetting agent from about 0.3 %w/w and remaining amount including of water. The foam density is about 0.04 gm/cm³. The stabilization of dyed yarns takes place in closed chambers in presence of nitrogen atmosphere. The application of the size in spray form. Example 2:

[42] A fabric having a plurality of foam dyed warp yarns comprising cotton spun yams having a yarn count of 8 Ne and a plurality of weft yams comprising stretch yarn having a yam count of 12csy + 70D Cotton spandex yarns. The weight of the fabric is about 11.5 Oz/sq. yd. and weave is 3/1 Twill.

[43] There have been described and illustrated herein several embodiments of a convertible device. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. The composition of oxidative dyes, fabrics, foam dyeing parameters, sizing parameters, stabilization parameters, drying parameters, predetermined temperatures, predetermined time periods, yarn counts, types of weaves, dyeing system parameters, total yam passage lengths are not limited to those described herein above and are provided only for reference and understating purpose of the invention. It will be appreciated that the embodiments may be manufactured with other types or units and further, the structure and design of the system and process may vary accordingly as well.

[44] It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms“including” is used as the plain-English equivalent of the respective term“comprising” respectively.

Claims

Claims :

1. A process for dyeing yarns, the process comprising the steps of:

preparing a sheet of yarns;

passing the sheet of yarns through a first foam dyeing unit of a dyeing system for continuously foam dyeing the yams with a class of dye having fading characteristics;

passing the foam dyed yams through a first stabilizing unit of the dyeing system for fixing dye onto the yarns about a predetermined time;

drying the foam dyed yams in a first drying unit of the dyeing system about at a predetermined temperature;

sizing the dyed yarns in a sizing unit of the dyeing system;

drying the sized yarns in a second drying unit of the dyeing system at said predetermined temperature; and

passing the dyed yarns through an accumulator of the dyeing system for wounding onto a weaver’ s beam for weaving the dyed yarns.

2. The process as claimed in claim 1, wherein the process after drying the dyed yarns in the first drying unit and before sizing in the sizing unit includes the steps of:

passing the foam dyed yarn through one or more augmentation unit each having a second foam dyeing unit with a class of dye same or different with same or different color shades and intensities than the class of dye of the first foam dyeing unit of the dyeing system and a second stabilizing unit, for obtaining a desired/ predetermined darker shade or different shades of dyed yarns;

washing dyed yams in a washing unit of the dyeing system for removal of unfixed dye from the yarns; and

partially drying the dyed yarns in a third drying unit of the dyeing system followed by sizing the dyed yam in sizing unit of the dyeing system.

3. The process as claimed in any of the preceding claims 1-2, wherein the yams are spun yarns and selected from the group of natural fibres or regenerated fibres or recycled fibres or elastomeric yan or combination thereof.

4. The process as claimed in any of the preceding claims 1-3, wherein the predetermined temperature of the drying units depends on yam moisture and temperature ranges from about 80“Celsius to 120 ° Celsius.

5. The process as claimed in any of the preceding claim 1-4, wherein the dyeing composition includes an oxidative dye from about 0.5 %w/w to about 5%w/w, a foaming agent from about 1.5%w/w to about 3% w/w, a wetting agent from about 0.3 %w/w to about 1% w/w and remaining water.

6. The process as claimed in any of the preceding claim 1-5, wherein foam density of the foam is about 0 02 gm/cm³ to about 0.05 gm/cm³.

7. The process as claimed in any of the preceding claim 1-6, wherein the predetermined time for fixing the shade of the foam dye onto the yarns is at least 1.5 minutes.

8. The process as claimed in any of the preceding claim 1-7, wherein oxidative dye includes indigo, sulphur, and vat dyes.

9. A system for dyeing yarns, the system comprising:

a first foam dyeing unit for dyeing a sheet of yams;

a first stabilizing unit having a closed chamber with a combination of gases including reactive and non-reactive gas that include nitrogen and helium for penetrating the dye into the foam dyed yarns and for fixing the dye;

a first drying unit for drying the dyed yams at a predetermined temperature; a sizing unit having a size box configured to spray a desired size through nozzles uniformly on sheet of yarns;

a second drying unit for drying the sized yarns at said predetermined temperature; and

an accumulator for accumulating the dyed yarns onto a weaver’s beam for weaving the dyed yarns as plurality of warp yarns for manufacturing denim fabrics.

10. The system as claimed in claim 9, wherein the system includes: one or more augmentation unit each having a second dyeing unit and a second stabilizing unit for obtaining a darker shade or different shades of dyed yarns;

a washing unit for removal of unfixed dye from the yarns; and

a third drying unit for partially drying the yams.

11. The system as claimed in any of the preceding claims 9-10, wherein total yam passage length of the dyeing system is 350 meters, with a stabilization unit having yam passage length of about 50-80 meters.

12. A fabric comprising:

a plurality of warp yams and a plurality of weft yams including spun yarns, comprising stretch or non-stretch yarns or combination thereof selected from the group of natural fibres or regenerated fibres or recycled fibres, or blend of natural fibres and elastomeric fibres and/or man- made fibres or blend of natural fibres with synthetic fibres or blend of recycled fibre with natural fibre and/or regenerated fibre, wherein the warp yarns are foam dyed and are obtained from the process as claimed in any of the preceding claims 1-8.

13. The fabric as claimed in claim 12, wherein the warp and weft yarn count ranges from 4s Ne - 60s Ne.

14. The fabric as claimed in any of the preceding claims 12-13, wherein weight of the fabric ranges from 1.5 oz. per square yards to 20 oz. per square yards.

The fabric as claimed in any of the preceding claims 12-14, wherein the fabric has colour fastness to rubbing about 3.5 - 4 in dry condition and about 1.5 - 2 in wet condition and a colour fastness to ozone about 4 - 4.5, when measured as per standard AATCC 8 method.

16. The fabric as claimed in any of the preceding claims 12-15, wherein the fabric is woven in denim weaves including twill, satin, sateen, or dobby.

17. The fabric as claimed in any of the preceding claims 12-16, wherein a garment is made from said fabric.