DESC:FIELD OF INVENTION
This disclosure is related to coloration of thermoplastic fibers and yarns, and fabrics made from the thermoplastic fibers with oxidative colors and manufacturing fabric and apparel from the colored fibers.
BACKGROUND OF THE INVENTION
Oxidative dyes are dyes where the color and/or hue is maximized after an oxidation step. Dyes in this class include and are not limited to vat dyes, sulphur dyes and the like. The oldest vat dye is Indigo which is used extensively to color natural fibers like cotton, silk and wool. Indigo is typically applied by ring dyeing fibers in rope/sheet form. Vat dyes are also suitable for exhaust and continuous dyeing systems.
Thermoplastic fibers have desirable functional properties which natural fabrics lack, such as crease recovery, and abrasion resistance (no chafe garments). In order to combine the functionality of thermoplastic fibers with the hues and look of vat dyes or sulfur dyes, dyeing thermoplastic fiber or yarns with oxidative colors is desirable. However, conventional oxidative dyeing methods are not applicable to thermoplastic fibers or yarns.
A thermoplastic fibers, filaments yarns, or fabrics thereof made of a polymer including acrylic fiber/filaments, or polyester fiber/filaments, nylon, nylon 66, PBT, and PLA fiber/filaments. Due to the larger size of oxidative dye molecules compared to the size of the monomers in the thermoplastic polymers, conventional methods of oxidative dyeing are not suitable for intercalation/adsorption of the oxidative dye molecules on the thermoplastic fibers.
There is a need in the field for methods of dyeing thermoplastic fibers with oxidative dyes.

SUMMARY OF THE INVENTION
Provided herein are methods for dyeing thermoplastic fibers with oxidative dyes, thereby allowing for retention of the functionality of the thermoplastic fibers (e.g., breathability, moisture wicking, low chafing etc.) while also providing for aesthetically pleasing colors. The oxidatively dyed fibers described herein are suitable for manufacture of fabric and/or garments thereof by woven, knitted, or nonwoven protocols typically used in the textile industry.
Accordingly, the present disclosure provides an exhaustion process for dyeing thermoplastic fibers, yarns, or fabrics said process comprising steps:
swelling the thermoplastic fibers, yarns, or fabrics at glass transition stage in a dye bath in presence of swelling agent,
adding an oxidative dye and a dispersing agent in the dye bath and allowing molecules of the oxidative dye to penetrate uniformly into the fibers, yarns, or fabrics,
adding a high temperature stable reducing agent and a buffer to the mixture, raising the temperature to about 110 -130 oC and maintaining the mixture for at least about 60 minutes,
adding an oxidation agent to the mixture; and
washing the dyed fibers, yarns, fabrics or for removal of insoluble or unfixed dyes to obtain wash-dyed fibers, or fabric.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
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:
Figure 1A: shows a process for manufacture of dyed non-woven fabric as described in Example 1; and
Figure 1B: shows a process for manufacture of non-woven fabric.
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. 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
Although specific terms are used in the following description for sake of clarity, these terms are intended to refer only to particular structure of the invention selected for illustration in the drawings and are not intended to define or limit the scope of the invention.
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.
References in the specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
In the textile industry, when dyeing fabrics or fibers/yarns, the nature of the fabric and the nature of the dye molecules can impact the efficiency and effectiveness of the coloring process. Oxidative dyes are generally insoluble in water, and consequently, the water soluble thermoplastic material does not pick up oxidative colors. The methods described herein allow for dyeing of thermoplastic fibers / fabrics with oxidative dyes/colors.
In one aspect provided herein is a method for dyeing thermoplastic fibers, filaments, and/or spun yarn, and garments or fabrics thereof that comprises an exhaustion process. The exhaustion process described herein is suitable for dyeing of thermoplastic fibers or fabrics comprising thermoplastic fibers. As used herein an “exhaustion process” or an “exhaust process” refers to a process where the fabric or fiber/yarn to be dyed is placed in an exhaustion chamber containing solvents and/or water and one or more dyes and any other ancillary reagents.
According to an embodiment, the present disclosure provides an exhaustion process for dyeing thermoplastic fibers or yarns is carried out in the exhaustion chamber. In the first step, the thermoplastic fibers or yarns are added along with swelling agents in the dye bath of the exhaustion chamber and swelled at glass transition stage in a dye bath in presence of swelling agent, then adding an oxidative dye and a dispersing agent in the dye bath and allowing molecules of the oxidative dye to penetrate uniformly into the fibers, yarns, or fabrics. After penetration, a high temperature stable reducing agent and a buffer are adding to the mixture and temperature of dye bath is raised to about 110 -1300C which is maintained for at least about 60 minutes. After that oxidation. Then an oxidation agent is added to the mixture and washed the dyed fibers, yarns, fabrics or for removal of insoluble or unfixed dyes to obtain wash-dyed fibers, or fabric.
The steps are now described herein below in detailed for understanding purpose. The term refers in thermoplastic fibers for reference purpose and to avoid mere repetitions and include staple fibers, yarns/filaments, and fabrics made from thermoplastic polymers. The thermoplastic polymer includes from acrylic fiber/filaments, or polyester fiber/filaments, nylon, nylon 66, PBT, and PLA fiber/filaments. Further, the yarns, and fabrics may include blends of the polymeric staples fibers or yarns/filaments with the man-made fibers or natural fibers.
In the first step, swelling agents are added along with the fiber in a dye bath, swelling agent helps to swell fibers. The swelling of the fibers is preferably performed at glass transition stage of the polymers for a predetermined time in a dye bath. Generally, the swelling is carried out at least for about 10 minutes. The swelling agent opens up pores of fibers.
The swelling agent at glass transition state of the polymers swells the fiber and ultimately causes relaxation and opening the internal fiber structure. The swelling agent comprises one or more of ortho-phenyl phenol, diphenyl, aromatic ethers such as Univadine DIFTM, emulsifiable solvents such as PEG, chlorinated aromatic compounds and esters thereof, di-methyl ester of terephthalic acid.
Once the fibers swells- up, oxidative dyes with dispersing agent are added in the dye bath. The swelling of the fibers allows the dye molecules to diffuse rapidly in the fibers. The swelling agents act as molecular lubricants reducing inter-molecular forces operating in the fiber, thereby following the dye molecule to force its way in. The oxidative dye added in the dye bath generally in the composition form comprising dispersing agents, sodium hydroxide, sodium hydro-sulfite, citric acid along with the oxidative dye. The composition is known to the person skilled in the art and the percentage of the oxidative dye in the composition depends upon the shade required to the fibers. Further, addition of the dispersing agent along with an oxidative dye to the mixture of first step, allows the molecules of the oxidative dye to penetrate uniformly into the fibers or fabric. The penetration process is also carried out for at least about 10 minutes. According to the present disclosure, the oxidative dye and the dispersing agent are added in the mixture at a temperature of about 70 0C -80 0C, more typically 800C.
In the context of the present invention, Setamol WSTM is used as a dispersing agent wherein a surface-active substance added to a suspension, usually a colloid, to improve the separation of particles and to prevent settling or clumping. Sodium Hydroxide acts as a stabilized reducing agent that maintains the pH of the process and Sodium Hydrosulphite / (Rongolite HTTM) acts as a reducing agent. The oxidative dye according to the present disclosure includes indigo or a sulphur dye.
During penetration, the temperature of the dye bath decreases. After about 10 minutes from the addition of the dye composition, a high temperature stable reducing agent is added. The reducing agent comprises a sulphonic acid derivative along with the pH buffer and the dyeing process temperature is again increased at a temperature to about 110-130 0C, more preferably to 110 °C which is maintained at least for about 60 minutes.
After confirming that the dyeing process is complete based on Optical Density and Shade depth, the temperature is reduced to 80 °C and oxidation step is carried out in the dye bath. The oxidation of the fiber-diffused dye molecules is carried out in the presence of oxidation agents such as hydrogen peroxide or Oxidant BRI Liq. Er. Other oxidation agents are contemplated within the scope of embodiments described herein. In the context of the present invention, the oxidation agent is added in the mixture at a temperature of about 70 0C-80 0C, more typically at 800C.
After oxidation step, the unfixed dyestuff is rendered water insoluble by oxidation, and removal of unfixed dyes is carried out. The unfixed dyes are removed by using hydrogen peroxide and dispersing agent. Finally, the material was washed with soap to remove all the chemicals. A non-ionic soap, namely Metaxil AWF, is used to wash the dyed material.
In one embodiment, the exhaustion efficiency of the exhaustion process described above is in a range of about 80 – 90%, more typically 85 %.

EXAMPLES
The following examples and comparative examples are provided to demonstrate particular embodiments of the present invention. It should be appreciated by those skill in the art that the methods disclosed in the examples and comparative examples that follow merely represent exemplary embodiments of the present invention. Those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments described and still obtain a like or similar result without departing from the spirit and scope of the present invention.

Example 1:
Dyeing of the Polyester fiber of 1.4 dpf and 51 mm staple length with Indigo is carried out by the steps described above. The method and making a non-woven fabric of 180 gsm for appeal is as follows.
In this fabric skin side is 1.7 dpf viscose fiber of 51 mm and face side along with a polyester ripstop fabric of 20 gsm in the middle as shown in FIG 1A.
As shown in FIG. 1B, the fabric is made by needle punching, and the non-woven fabric is subjected to gas singeing and chemical finishing as desired.
The process described herein is employed in preparing the fabrics described in the examples below.
Example 2:
Polyester Filaments of 150 Denier were dyed with Indigo dyestuff and converted to single jersey fabric of knitted denim for sport wear/ casual wear.
Example 3:
Acrylic yarn of 34s Ne was dyed with Indigo and converted to a knitted Polar Fleece for denim winter wear.
Example 4:
20s Ne Tencel is dyed with indigo using rope/sheet dyeing.
100 Denier Nylon 66 dyed with sulphur dyed is converted to a woven fabric in warp as 20s ne Tencel yarn and in weft 100Denier Nylon 66. For denim sport wear/casual wear.
Example 5:
For casual wear, warp is 30s Ne Tencel yarn with indigo and weft is 150 D T400 stretchable polyester like T 400 dyed with sulphur.
Example 6:
Knitted garment made of polyester and dyed with sulphur dyestuff for casual wear.
It is found that the oxidative dye penetrates in the thermoplastic fibers, yarns, and fabrics deeply and gives a look of vat dyes or sulfur dyes to the thermoplastic fibers, yarns, fabrics and garments. The process is cost effective.
The blend of natural or regenerated fibers with thermoplastic fibers gives denim look with a controllable wash. It also provides temperature management property.
In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This device or unit or arrangement of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment.
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” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively.
,CLAIMS:
1. An exhaustion process for dyeing thermoplastic fibers, yarns/filaments or fabrics thereof, said process comprising steps:
swelling the thermoplastic fibers, yarns/filaments or fibers in the fabric at glass transition stage in a dye bath in presence of swelling agent;
adding an oxidative dye and a dispersing agent in the dye bath and allowing molecules of the oxidative dye to penetrate uniformly into the fibers, yarns/filaments or fabric;
adding a high temperature stable reducing agent and a buffer to the mixture;
raising the temperature to about 110 -130 oC and maintaining the mixture for at least about 60 minutes;
adding an oxidation agent to the mixture; and
washing the dyed fibers, or fabric for removal of insoluble or unfixed dyes to obtain wash-dyed fibers, or fabric.

2. The process as claimed in claim 1, wherein the exhaustion efficiency of the exhaustion process is in a range of about 80 – 90%.

3. The process as claimed in claim 1, wherein the swelling agent is ortho-phenyl phenol, diphenyl, aromatic ether, emulsifiable solvents, chlorinated aromatic compounds and esters thereof, or di-methyl ester of terephthalic acid, or any combination thereof.

4. The process as claimed in claim 1, wherein the high temperature stable reducing agent comprises a sulphonic acid derivatives.

5. The process as claimed in claim 1, wherein the oxidative dye includes indigo or a sulphur dye.

6. The process as claimed in claim 1, wherein the oxidative dye and the dispersing agent are added in the mixture at a temperature of about 70 0C -80 0C.

7. The process as claimed in claim 1, wherein the oxidation agent is hydrogen peroxide.

8. The process as claimed in claim 1 or 7, wherein the oxidation agent is added in the mixture at a temperature of about 70 0C -80 0C.

9. The process as claimed in claim 1, wherein the thermoplastic fibers, filaments/yarns or fabrics thereof are include acrylic fiber/filaments, or polyester fiber/filaments, nylon, nylon 66, PBT, and PLA fiber/filaments.

10. The process as claimed in claim 1, wherein the swelling step and penetration step of the dye are carried out for at least about 10 minutes.