RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application Serial No. 62/845,889, filed May 10, 2019, which is incorporated by reference in its entirety.

FIELD

[0002] The present disclosure relates to a process of rapid drying and color fixation on a set of moving yam or thread substrate comprising multiple individual yams of different colors. It also relates to an integrated process for coloring and drying individual yams or threads among a set provided in parallel, followed by color fixation into the yam at a rate consistent with direct coupling to a dependent process of fabric formation, including tufting, weaving and the like.

BACKGROUND

[0003] Since the middle of the 20 ^th century, commercial, residential and industrial applications of carpets have exponentially grown into a significant global market. Previously, carpets typically consisted of wool, but recent advancements in the synthetic fibers have led to the use of nylon, polyester and polyolefin [polypropylene, for example] fibers and yams as less expensive, long- lasting and durable alternatives to wool.

[0004] The term "carpet" is often used interchangeably with the term "mg", although the term "carpet" can be applied to a wall-to-wall floor covering, whereas a "mg" is a partial floor covering and can be spread over any floor. Carpets and mgs can be made in any color by using differently dyed yams. Solution dyed yams are often used in carpet tufting. Alternatively, tufted white carpets can be dyed or printed in desired colors and patterns. Carpets made from colored or solution dyed yams have superior aesthetics compared to printed and dyed carpets. Carpets can have many different types of patterns and motifs used to decorate the surface. To date, solid-colored and multi-color-patterned carpets and mgs are used in industrial and commercial establishments such as retail stores, hotels, restaurants, residential homes, etc. [0005] As the consumer demand grows for uniquely designed and aesthetically superior multi color-patterned carpets made of synthetic fibers, say, nylon or polyester, industrial processes are needed for making such flooring products cost-effectively while meeting or exceeding the end-use performance requirements. Most of the specialty carpet manufacturers today employ pre-colored yams to create specialized designs. Pre-colored yam can be created by inclusion of pigments in the polymer of a synthetic fiber spinning process. Alternatively, color may be provided by bulk package dying in a dye bath, or by spray dyeing griege yam, winding, storing, and transferring it for later use. In any case, using pre-colored yams in carpet tufting creates operational complexity with additional stock keeping units (SKUs) inventory investment, inventory storage costs, and additional labor for material handling and productivity losses due to extended transition times for product changeovers. In the case of modem carpet styling options for designer patterns today, yams are produced in various colors, and a selection of yarns is then placed in a creel and stmng up to the tufting machine. Removing and replacing yam packages in order to change colors and patterns can take several people a number of hours, during which time the tufting machine is unproductive. In view of the above, it would be highly desirable to have a process to color individual carpet yams to be fed directly to the tufting process without the requirement to inventory a wide range of colors, or to remove and replace yam in the tufting creel with every design transition. Whether such capability is provided to every end feeding a fabric formation process or just a small subset, it can be well appreciated by one skilled in the art that successful commercial practice of such a coupled yam coloring process would require the colored yams to be accurately and deeply dyed, that the provided color would be permanent, color fast, and would not mb off in processing, handling or subsequent use, and that the speed of yam through the coloring process would be fast enough to match the speed of the fabric -forming (or tufting) process being fed.

[0006] Known yam coloring methods [including those taught in WO2017203524A1, W02017200473A1, WO2017155451A1, US20160102430A1] generally focus on applying single colors rather than coloring, drying and color fixation on multiple yams of different colors. Another technical problem to be overcome is yam speed. It would be desirable to color the yams and then directly transfer them to a tufting machine. The problem is that the inlet yam speed for a tufting machine is typically greater than lOm/min. Known methods have not proven satisfactory for coloring yams at this linear velocity, and this is especially true for heavy denier, bulked carpet yams. [0007] The process of the present disclosure provides a basis for high linear feed rates as required, by selection and unique combination of ink/colorant type, drying process and ink fixation process. The process of the present disclosure enables coloration, drying and fixation of multiple yams of different colors without color transfer/contamination between adjacent yams and color transfer/contamination from yam to guide rolls and other parts of the machine. The process of the present disclosure also provides a way of maintaining almost zero tension in color fixation stage for bulked/crimped yams to avoid loss of bulk/crimp at high temperature.

SUMMARY

[0008] Disclosed is a process for coloring a yam, the process comprising:

a) applying a sublimation ink to the yam;

b) exposing the yam comprising the sublimation ink to drying conditions including raising the surface temperature of the yam above ambient but below melting point of the yam by applying radiant heat to the yam for irradiation time sufficient to reduce the moisture content of the yam to provide an at least partially dried yam without touching other surfaces; and

c) exposing the at least partially dried yam to curing/fixing conditions including

conductive and convective heat transfer conditions above ambient temperature for a residence time sufficient to provide a fixed yam;

[0009] wherein the sublimation ink applied in step (a) and at least partially dried in step (b) yam diffuses more deeply into the center of individual fibers of the yam in step (c) than would be observed in applying the sublimation ink and fixing the sublimination ink in the absence of intermediate drying step (b).

[0010] Sublimation ink (colorant) can be applied to the yam using any suitable method known to those skilled in the art. One example of such a method is disclosed in commonly-assigned PCT Patent Application PCT/IB2019/060057. Applying sublimation ink via ink-jet printing is preferred, but not required. Ink-jet application is desirable because (among other reasons) it enables coloration of different yams in different colors and provides better color control than an analog coloration method.

[001 1] Yam can be one yam or multiple yams in parallel. The skilled person will appreciate that the term“yam” is used herein to refer to filaments, threads, fibers, yams, and yam bundles.

[0012] Step (b) can further comprise exposing the colored yam to radiant energy at wavelength of from 0.7 pm and 4.0 pm.

[0013] Step (b) can further comprise controlling the radiant energy density at the surface of the yam. For example, when the yarn comprises nylon-6,6, the radiant energy density at the surface of the fluid-treated elongated substrate is suitably controlled at from > 10 Joules/cm2 to < 2000 Joules/cm2; for example, from > 20 Joules/cm2 to < 1000 Joules/cm2; for example from > 30 Joules/cm2 to < 600 Joules/cm2.

[0014] The at least partially dried yam of step (b) comprises < 5 % moisture, based on the weight of untreated yam.

[0015] Step (c) can comprise curing the at least partially dried ink/colorant.

[0016] The combined residence time in the first step and the second step can, for example, be > 100 milliseconds to < 80 seconds. The combined residence time in the first step and the second step can be > 5 seconds to < 75 seconds.

[0017] The residence time in the first step can be from >1% to <25% of the combined residence time. For example, the residence time in the second step is from >75% to <99.9% of the combined residence time.

[0018] The yam can have fibers of any suitable cross-sectional shape, with examples including round, trilobal, multi-lobal, square, rectangular, triangular, oval and star. The yam can have fibers of a cross-section type chosen from the group consisting of solid, hollow, partially solid and partial hollow.

[0019] The disclosed process can be carried out as an individual unit operation. The disclosed process can also be operated with downstream tufting.

[0020] A device for drying and curing/fixing a colored yam comprising sublimation ink(s) is also disclosed. The device can comprise:

a) a guide for transporting a yam through a drying space without touching other surfaces; b) at least one radiation energy source for transmitting thermal energy to the yam in the drying space for residence time sufficient to provide an at least partially dried yam; c) guide for conveying the at least partially dried yam of b) through a curing space; and d) Conduction and convection energy sources for providing uniform thermal energy input to the yam and maintaining the residence time in the curing space to obtain a cured yam.

[0021] The drying space of the disclosed device can comprise at least one infrared [IR] radiation emitter. Suitable infrared radiation emitters emit infrared radiation in the wavelength range of between 0.7 and 4.0 pm. The device suitably provides residence time in the drying space to produce a yam with < 5 % moisture. The device includes a curing space comprising at least one heated chamber and at least one conductively heated metallic conveyor inside the heated chamber. The curing space of the device is suitably maintained in the temperature range of between 120 °C and 250 °C, for example, between 130 °C and 240 °C.

BRIEF DESCRIPTION OF THE FIGURES

[0022] FIGURE 1 is a schematic representation of an embodiment 101 according to the present disclosure.

[0023] FIGURE 2 is a schematic representation of an embodiment 201 according to the present disclosure.

[0024] FIGURE 3 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 1 of the present disclosure.

[0025] FIGURE 4 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 2 of the present disclosure.

[0026] FIGURE 5 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 3 of the present disclosure.

[0027] FIGURE 6 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 6 of the present disclosure.

[0028] FIGURE 7 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 7 of the present disclosure.

[0029] FIGURE 8 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 8 of the present disclosure.

[0030] FIGURE 9 is a cross-sectional analysis result of dye diffusion and fixation into the yam according to Example 9 of the present disclosure.

DETAIUED DESCRIPTION

[0031] The present disclosure relates to a combination of fast drying step followed by rapid colorant/dye fixation step for a color-applied yam, thread or multiple yams.

[0032] The present disclosure may be suitable for both, bulked as well as flat yams.

[0033] Suitable colorants include sublimation inks. Sublimation inks can be cured without steaming and minimize wet processing which is common in processing of textiles and yams. Sublimation inks are also uniquely suited to the present disclosure because sublimation inks don’t leave any deposits on heated metallic conveyors used in curing step, if the temperature of heated metallic conveyors is above sublimation temperature of the dye. Depending on the base carrier, ink type could be water-based (aqueous), solvent-based, or oil-based. Ink may also contain surfactants, humectants, viscosity modifiers, binder resins, pH modifiers, and other functional chemicals as needed.

[0034] Once the ink is applied to a textile yarn or substrate, it is necessary for the colorant to infuse into and dye the fiber, thus becoming part of the substrate itself. This process is known as ink curing or dye fixation. Industrial drying and fixation techniques such as convection oven, infrared oven and steaming are most commonly used for colored yams. In some cases, microwave, RF and acoustic technologies are used. The total residence times in all these processes are typically several minutes long. These traditional drying and curing processes use one type of heat transfer technology common to both drying and curing. Though such technologies may be available, these traditional drying and color fixation processes tend to be slow, and may not be particularly suitable for bulked yams because bulked yams are very sensitive to heat and tension during drying and fixation process. Prolonged heat and tension conditions can lead to loss of crimp/bulk in yam/fibers. In some cases, yam is laid in coiled form to avoid loss of crimp/bulk. Such processes are not suitable for closely-spaced multiple yams of different colors.

[0035] The present disclosure solves the problem of exposing color-applied yarn or thread to heat and tension for minutes in the traditional drying and color fixation processes. The present solution relates to a combination of fast drying step followed by rapid colorant/dye fixation step applied to a color-applied yam, thread or multiple yams, such that the yam or thread does not experience prolonged heat and tension conditions.

[0036] In one embodiment, the present disclosure relates to separating the drying and curing steps where each step is designed to maximize the performance. In addition, this solution facilitates handling of bulked yarns without stretching out the crimp/bulk.

[0037] FIG. 1 is a schematic representation of an embodiment 101 according to the present disclosure. In FIG. 1 guide rolls labeled 3a, 3b and 3c guide a continuous color-applied yam or thread through the various processing units. Not shown in FIG.1 are other possible variations of the guide rolls, such as, size, number, location, orientation, directional movement, etc. A skilled person in the field of fiber/yam processing will appreciate that the yam tension may be controlled separately in each location depending on the individual processing steps. Commercial means for moving the thread(s) or yam(s) may be employed for the desired processing speed and consistency. Yam tension in both drying step and fixation step are kept very low so that there is no significant loss of fiber crimp in bulked yams. Heated metallic conveyors enable transport of yam inside fixation unit with almost no tension. Temperature inside the fixation unit is high to enable sublimation of ink and, therefore, maintaining low tension is very important in fixation step. For example, the yam tension in the fixation step can suitably be from > 0 to <=0.02 g/denier based on yam denier.

[0038] Referring to FIG. 1, a color-applied wet yam 11 is guided in a drying unit 21, wherein the yam spends adequate time at the condition that decreases the moisture content present in the yam as it passes through. The colored yam 31 exiting the drying unit has a lower moisture content than that in the yam 1 1 at the entrance of unit 21.

[0039] The dry yam 31 is further guided into a dye fixation unit 41. In unit 41 dye diffusion and fixation in the yam substrate may be accomplished by exposing the yam to elevated temperatures for some suitable time. The fixation unit 41 may be designed such that the yam spends adequate time at the pre-determined elevated temperature and the dye is fixated in the yam. The dye fixation is complete for the yam 51 which is guided out by guide rolls 3c at the fixation unit 41 exit.

[0040] Though not shown in the figures, it is possible to process more than one yam or thread in parallel through the processing units capable of handling parallel lines [or a sheet of equally spaced yam or thread] through their processing regions. A reasonable spacing can be maintained between the two neighboring yams, strands or threads by way of guide rolls/spacers.

[0041] In one embodiment, the present disclosure provides a unique design and combination of Infra-red [IR] technology and rotary heat press that enable fast drying and rapid dye fixation during the color-applied yam process. The rotary heat press includes moving heated metal conveyors that are enclosed in a heated chamber to provide uniform heating.

[0042] FIG. 2 is a schematic representation of an embodiment 201 according to the present disclosure. In FIG. 2, a drying unit 22 represents an IR technology setup equipped with two emitters. The color-applied wet yam 12 undergoes drying in the drying unit 22 that uses an IR technology consisting of two emitters of sufficient energy output (say, wattage). The two emitters may be arranged to face each other with the colored yam 12 passing in between the two emitters. The IR emitters are designed to be of adequate length as desired for the drying performance. The color-applied yam 12 speed may also be controlled for optimum drying. The moisture content in the yam 13 exiting the drying unit 22 is lower than that at the drying unit inlet, i.e., yam 12 at roller 5a location.

[0043] The dried yam is then passed through a dye fixation step, which consists of slow- moving heated metal conveyors 32 housed inside the heated chamber 42. The temperature of both, heated chamber 42 and heated metal conveyors 32 may be maintained and controlled to a suitable temperature.

[0044] In one embodiment, the heated chamber 42 houses an assembly of one or multiple metal conveyors 32. The metal conveyors 32 are guided by multiple sets of end rollers 72 turning around their center axes such that horizontal serpentine flow arrangement is obtained for the material being carried by the conveyors. Other non-limiting arrangements may include one or multiple assemblies of moving surfaces having the continuity to carry the material from inlet to the outlet of the unit. Such arrangements may be vertically mounted, horizontally mounted, inclined or combinations thereof. Units 5a, 5b and 5c schematically represent the guide rollers for a previously colored yam 12 to stay on track as it passes through the units. Other mechanical details, not shown in FIG. 2, are known and understood to a skilled person in the field of fiber/yam processing.

[0045] The uniformly heated chamber 42 may also prevent accumulation of the possible condensable materials evolving from the yam inside the dye fixation unit. Such condensable materials may include glycols, solvents, residual moisture and dye constituents present in the vapor phase. The stream 62 represents an exhaust stream that would remove such condensable materials out of the heated chamber 42. The drying and dye fixation of the moving yam 52 at the exit of the heated chamber 42 may be complete and uniform across the fiber cross-section in the yam.

[0046] The residence time for the moving yam inside the drying unit 22 may be in the range of about 0.1 seconds to about 15 seconds. The residence time for the moving yam in contact with the heated metal conveyors 32 may be in the range of about 5 seconds to about 60 seconds. For example, the yam length of about six meters may provide adequate residence time of about 18 seconds from start to end once inside the heated chamber 42 and onto the metal conveyors 32. The combined residence time of the moving yam through drying unit 22 and fixation unit 42 time may be about 75 seconds, about 50 seconds, about 30 seconds, about 20 seconds or about 5 seconds.

[0047] Examples of colored yam drying setup may include Infra-red [IR] wavelength technology. Infrared [IR] heating or drying involves heat transfer by radiation between a hot element and a material at lower temperature that needs to be heated or dried. The hot elements consist of gas emitters or electrical lamps which are aligned in order to create a heating region(s) or zone(s). The peak wavelength of the radiation is dependent of the temperature of the heated element. Thermal radiation is described as infrared in the electromagnetic spectrum between the end of the visible, i.e., between 0.78 pm and 1000 pm. In general, infrared radiation is split into three main categories, in function of the wavelength peak of the radiation: Short-wave IR (SwIR): from 0.78 pm to 2 pm, Medium-wave IR (MwIR): from 2 pm to 4 pm, and Long-wave IR (LwIR): from 4 pm to 1000 pm.

[0048] In one embodiment, the preferred IR wavelength may be in the range of 0.7 pm to 3.0 pm. For example, the near-IR or NIR wavelength range of 0.7 pm to 1.2 pm; short-wave IR [SwIR] wavelength range of 1.2 pm to 2.0 pm; part of medium-wave IR [MwIR] wavelength range of 2.0 pm to 3.0 pm.

[0049] The drying unit may be designed to operate in horizontal, vertical or inclined orientation.

[0050] The IR emitter wattage may depend on the number of yams (or threads) being processed, and also on the moisture content of the colored yam at the entrance of the IR drying setup. The IR emitter length may depend on the yam movement speed through the device, which may be designed to provide adequate residence time in the unit.

[0051] In some embodiments, more than one IR module may be used in series, in parallel or combinations thereof. Such modules may have different IR wattage outputs, different emitter lengths to give different residence times, and combinations thereof.

[0052] Examples of ink fixation step may include an arrangement where the colored (dried) yam may pass through and spend some time in a heated environment. In one embodiment, the fixation step may include a heated chamber where the yam is moved over a series of metal conveyors for adequate exposure time at the design temperature. The temperature inside the heated chamber may be maintained up to 250 °C, and preferably in the 150 °C to 220 °C range. The surface temperature of the heated metal conveyors may be maintained up to 250 °C, and preferably in the 150 °C to 220 °C range. The temperature may vary from one metal conveyor to the next in order to provide an optimal temperature gradient for optimal dye diffusion and fixation in the fibers.

[0053] The number of repeating heated metal conveyors, conveyor lengths and the spacing between the conveyor stacks may vary depending on the yarn thickness and desired residence time.

[0054] It may be possible for the drying unit and fixation unit to be operating in-line, out-of- line, and in any orientation, i.e., vertical, horizontal or inclined with respect to each other.

[0055] The following Table provides exemplary conditions for both drying and fixation steps for different substrates

Table - Exemplary Substrates, Fluid Treatments and Conditions

EXAMPLES

EXAMPLE 1

[0056] A two-ply nylon 66 yam, denier 2490, 128 filaments, 4.5 twists per inch [tpi], is printed/colored using sublimation inks. The ink usage rate is 10% on weight of the yam.

[0057] FIG. 2 is a schematic representation of an embodiment 201 according to the present disclosure. In FIG. 2, a drying unit 22 represents an IR technology setup equipped with two emitters. A heated chamber 42 houses an assembly of metal conveyors 32. The stream 62 represents an exhaust to remove evolved condensables in the vapor-phase out of the heated chamber. The metal conveyors 32 are guided by multiple sets of end rollers 72 turning around their center axes such that horizontal serpentine flow arrangement is obtained for the material being carried by the conveyors. Units 5a, 5b and 5c schematically represent the guide rollers for a yam 12 to stay on track as it passes through the units. Other mechanical details are not shown in FIG. 2.

[0058] The above color-applied wet yam 12 is dried using an IR technology setup 22 consisting of two emitters of about 2.1 KW each facing each other with the colored yam 12 passing in between the two emitters. The IR emitters are 10 inch in length. The colored yam 12 speed is maintained to about 20 m/min. The moisture content in the yam 13 exiting the drying unit is measured to be 3.6 % by weight. The dried yam is then passed through a dye fixation step, which consists of slow-moving heated metal conveyors 32 inside the heated chamber 42. The temperature of both, heated chamber 42 and heated metal conveyors 32 is maintained at 210 °C. The yam length that is in contact with the heated metal conveyors 32 is about six meters and provides adequate residence time of about 18 seconds from start to end once inside the heated chamber 42 and onto the metal conveyors 32. The combined drying unit 22 and fixation unit 42 time for the moving yam is about 20 seconds, which is much shorter than the traditional methods available.

[0059] The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the individual fiber, as shown in FIG. 3. Dye is not only present close to the surface of individual fiber but also diffuses into the center of each colored fiber. The individual four-hole cross-section fibers show complete dye penetration and fixation on the fiber surface and inside the fiber.

EXAMPLE 2 - Comparative

[0060] A two-ply nylon 66 yam, denier 2490, 128 filaments, 4.5 twists per inch [tpi], is printed/colored using sublimation inks. The ink usage rate is 10% on weight of the yam.

[0061] The above colored yam is dried and dye fixation is performed using a conventional convection oven maintained at 210 °C for about 30 seconds.

[0062] The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the fiber, as shown in FIG. 4. The individual four-hole cross-section fibers show non- uniform and incomplete dye penetration and fixation. Most of the ink remains on the surface of the fibers with no ink fixation inside the fibers.

EXAMPLE 3 - Comparative

[0063] In this example, the setup and procedure described in Example 2 are used, except the colored yam is dried and dye fixation is performed by increasing the exposure time in the 210 °C convection oven to about 4 minutes instead of 30 seconds as in Example 2.

[0064] The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the fiber, as shown in FIG. 5. In this example, a longer exposure time results in complete dye coloration and fixation on the fiber surface and inside. However, the drying and fixation times for colored yams with such conventional methods are typically of the order of minutes versus in seconds according to the present disclosure, and therefore, too long from a processability perspective. The longer the drying and fixation times, the slower will be yam movement rate through the equipment, and correspondingly, there will be lower downstream processing throughput. Such process cannot be coupled to a conventional tufting machine due to the difference in the yam speeds between color fixation process and tufting process.

EXAMPLE 4

[0065] In this example, the setup and procedure described in Example 1 are used, except that dye drying and fixation steps are designed to process up to 50 yams or threads in parallel. These 50 threads run as a parallel sheet at the same speed of 20 m/min and through the IR emitters and metal conveyors inside the heater chamber. [0066] The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the fiber. It shows complete dye penetration and fixation on the fiber surfaces and inside the fibers, according to the present disclosure. The overall drying and dye fixation times are of the order of 20 seconds for all 50 yams processed in parallel.

[0067] This example illustrates drying and dye fixation for a multi-yam coloration system and scalability aspects.

EXAMPLE 5

[0068] In this example, the setup and procedure described in Example 4 are used, except that dye drying and fixation steps are designed to process up to 2000 yams or threads in parallel. These 2000 threads run as a parallel sheet at the same speed of 20 m/min and through the IR emitters and metal conveyors inside the heater chamber.

[0069] The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the fiber. It shows a uniform and complete dye penetration and fixation on the fiber surfaces and inside the fibers, according to the present disclosure. The overall drying and dye fixation times are of the order of 20 seconds for all 2000 yams processed in parallel.

[0070] This example further illustrates the scalability aspect of the present disclosure and its practicability for performing a multi-yam process.

EXAMPLE 6

[0071] In this example, the basic setup and procedure described in Example 1 are used, except that drying and fixation steps are designed to process up to 25 yams or threads in parallel. These 25 yams mn as a parallel sheet at the same speed of 12 m/min and through the IR emitters and metal conveyors inside the heater chamber. Yam type is two-ply nylon 6 yam, denier 2490, 128 filaments, 4.5 twists per inch [tpi], is printed/colored using sublimation inks. Sublimation ink is Elvajet Cyan SR340 from Sensient Colors LLC. The ink usage rate is 10% on weight of the yam. Drying unit consists of three IR emitters placed on one side of the yarns. Each IR emitter is about 5.4 KW and about 1.5-micron wavelength. Heated length of each emitter is about 24 inches. The temperature of both heated chamber and heated metal conveyors is maintained at 185°C. The yam length that is in contact with the heated metal conveyors is about six meters and provides adequate residence time of about 30 seconds from start to end once inside the heated chamber and onto the metal conveyors. The combined drying unit and fixation unit time for the moving yam is about 34 seconds, which is much shorter than the traditional methods available.

[0072] The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the fiber, as shown in FIG.6. It shows complete dye penetration and fixation on the fiber surfaces and inside the fibers, according to the present disclosure.

EXAMPLE 7 - Comparative

[0073] The same yam as Example 6, two-ply nylon 6 yam, denier 2490, 128 filaments, 4.5 twists per inch [tpi], is printed/colored with the same ink and usage rate. The colored yam is dried and dye fixation is performed using a conventional convection oven maintained at 185°C for 34 seconds, the same temperature and residence time as Example 6. The dye fixation quality is confirmed using a cross-sectional analysis of dye diffusion into the fiber, as shown in FIG. 7. The individual four-hole cross-section fibers show non-uniform and incomplete dye penetration and fixation. Most of the ink remains on the surface of the fibers with no ink fixation inside the fibers.

EXAMPLE 8

[0074] In this example, the setup and procedure described in Example 6 are used, except that yam type is polybutylene terephthalate. The temperature of both heated chamber and heated metal conveyors is maintained at 195°C. The dye fixation quality is confirmed using a cross- sectional analysis of dye diffusion into the fiber, as shown in FIG.8. It shows and complete dye penetration and fixation on the fiber surfaces and inside the fibers, according to the present disclosure.

EXAMPLE 9

[0075] In this example, the setup and procedure described in Example 1 are used, except yam type of polyethylene terephthalate, two-ply, 2340 denier, 260 filaments and trilobal cross-section is used. The temperature of both heated chamber and heated metal conveyors is maintained at 200°C. The dye fixation quality is confirmed using cross-sectional analysis of dye diffusion into the fiber and found to be satisfactory, as shown in FIG.9.