Patent Application
20240360620
The present invention relates to cellulosic yarn dyeing, such as for use in manufacture of fabrics for garments, using indigo or sulphur dyes in general and, more particularly, to a process providing a dyed yarn having reduced dye penetration and a white core, i.e., ring dye effect. The invention also is directed to yarns dyed on dye ranges through use of the process, and fabrics formed from the dyed yarns.
Indigo and sulfur continuous yarn dyeing typically results in solid dyed (no ring dyed) or partially ring dyed cellulosic yarns. The parameters which control the degree of ring dyeing for indigo and sulfur continuous yarns are indigo and sulfur dye properties, immersion time, air oxidation time, pH, dyeing temperature, yarn twist, yarn tension on the continuous dyeing machine, and others.
Sulfur dye, once dyed on cellulosic fiber, forms a bigger molecule due to dye and cellulose bonding. For the case of indigo dyeing over sulfur dye, this large molecule covers the free sites of cellulose and forms a barrier for the indigo dye molecule to enter towards the core of the yarn. To protect the core of the cellulosic yarn and create a ring of dyed fiber on the circumference of the yarn, the sulfur dyeing should be in ring form. To restrict the sulfur dye to the ring form on cellulosic yarn, the dyeing recipe and process parameters of conventional practices do not achieve the ring dyeing effect. For these purposes, we mean the ring dye effect as the outer periphery of the yarn being dyed with an internal white or near white core largely undyed. Because of the ring dye effect, laser abrading may be utilized to achieve the worn look without requiring the use of potassium permanganate and other harsh chemicals, which are hazardous to the environment.
The present invention is directed to a method for dyeing yarns to be used in manufacture of fabrics to be assembled into garments. The invention is directed to garments manufactured from such yarns.
A method of ring dyeing a yarn comprises a series of steps, including providing a yarn chosen from the group consisting of open-end yarns and ring yarns. The yarn is immersed for between 7 to 40 seconds in a caustic bath having a caustic concentration of 50 to 175 g/l. The yarn is skyed after removal from the caustic bath. The yarn is rinsed in water after skying. The yarn is chosen from one of open-end yarn and ring yarn and is dyed in only one sulfur dye box when the yarn is open-end yarn and ring yarn or is dyed at least one indigo dye box when the yarn is open-end yarn. The yarn is washed in water after the dyeing step and thereafter the dyed yarn is dried.
A method of ring dyeing a yarn comprises a series of steps, including providing an open-end yarn or a ring yarn. The yarn is immersed in a caustic bath having a caustic concentration of 50 to 175 g/l for between 7 to 40 seconds. The yarn is rinsed in water at room temperature. If the dye is a sulfur dur then the open-end yarn or the ring yarn is immersed in sulfur dye in only one sulfur dye box. The yarn is washed immediately after dyeing in water at room temperature, and thereafter the dyed yarn is dried. A method of ring dyeing a yarn comprises a series of steps, including providing an open-end yarn. The yarn is immersed in a caustic bath having a caustic concentration of 50 to 175 g/l for between 7 to 40 seconds. The yarn is rinsed in water at room temperature. The open-end yarn is immersed in at least one indigo dye bath. The open-end yarn is skyed after indigo dyeing; The open-end yarn is washed after skying in water at room temperature.
The accompanying drawings are incorporated in and constitute a part of the specification. The drawings, together with the general description given above and the detailed description of the exemplary embodiments and methods given below, serve to explain the principles of the invention. The objects and advantages of the invention will become apparent from a study of the following specification when viewed in light of the accompanying drawings, in which like elements are given the same or analogous reference numerals. In these drawings:
Reference will now be made in detail to exemplary embodiments and methods of the invention as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not limited to the specific details, representative devices and methods, and illustrative examples shown and described in connection with the exemplary embodiments and methods.
This description of exemplary embodiment(s) is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “upper”, “lower”, “right”, “left”, “top” and “bottom”, “front” and “rear”, “inwardly” and “outwardly” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. The term “integral” (or “unitary”) relates to a part made as a single part, or a part made of separate components fixedly (i.e., non-moveably) connected together. The words “smaller” and “larger” refer to relative size of elements of the apparatus of the present invention and designated portions thereof. Additionally, the word “a” and “an” as used in the claims means “at least one” and the word “two” as used in the claims means “at least two”. For the purpose of clarity, some technical material that is known in the related art has not been described in detail in order to avoid unnecessarily obscuring the disclosure.
Example 1.1 is a yarn 101 dyed completely or nearly completely to the core, i.e., having a complete or nearly complete dye penetration 12d, and leaving very little of the original white core 12c. The yarn 101, when viewed as a cross-section, may appear to be solid in color, or possibly lighter in color toward the core 12c1 but still obviously dyed through to the core 12c1.
Example 1.2 is a yarn 102 with significant dye penetration 12d, which to the unassisted eye still appears quite dark. The core 12c of the yarn 102 may be an even lighter color, or possibly even have a few fibers within the center that appear white, but the excessive penetration by the dye creates a barrier difficult to penetrate by laser abrasion.
Example 1.3 is a yarn 103 with a core 12c3 that with the unassisted eye appears to be white, or a significantly lighter shade. The dye penetration 12d is difficult to penetrate by laser abrasion as it extends too far from the perimeter of the yarn 103.
Example 1.4 is a yarn 104 that is dyed without consistency as measured from the perimeter of the yarn 104. The yarn 104 has a large area of the yarn that is undyed, revealing lighter shades of dye or even large areas of white in the yarn. These are some of the least desirable yarns, as they result in streaking and inconsistencies after weaving, with uncontrolled portions being dyed vs undyed. Similarly, laser penetration is received as randomly as the dye, leaving patches and undesirable peppering of areas that were intended to have dye removed, but many areas are impenetrable.
Example 1.5 illustrates ring dyeing: a lesser degree of dye penetration forming a concentric ring 12d while leaving the central core of the yarn without dye, i.e., displaying consistency in dye penetration with a dark shade on the perimeter of the yarn 105 and a white or nearly white core 12c5. This type of yarn readily receives laser energy sufficiently to eliminate the need for potassium permanganate and/or oxidative or reductive treatment conventionally used to remove dye in the manufacturing of garments. This type of yarn has improved ring dyeing effect for indigo dyeing, sulfur dyeing, or a combination thereof.
Preferably, implementation of the disclosed invention results in consistent dye penetration of about 10% to about 35% of the cross-sectional area of the yarn as measured inwardly from the perimeter of the yarn. Dyeing the periphery with controlled depth penetration and allowing the core to remain white is advantageous, particularly when the fabric woven from the yarn is to be subjected to laser abrasion, manual abrasion, and/or oxidizer treatments to remove color. Conventional dyeing requires use of potassium permanganate, which is hazardous to the environment and adds cost to garment washing treatment of the resulting fabric.
Yarn dyed according to the disclosed invention is preferably an open-end yarn and/or a ring yarn, both typically made of cotton fibers. The randomness of the fibers introduces some variables which, when paired with inconsistencies in twist, etc., results in some variation in dye penetration relative to the perimeter of the yarn. Implementation of the disclosed invention minimizes the dye penetration variation. While we prefer use of cotton yarns, the yarns of the present invention may include cotton, cellulose blends, and modified cellulose yarns like Viscose, Lyocell, and their blends.
Open-end yarns are known in the art and can be produced without using a spindle. The spindle is one of the core components of yarn making. Open-end yarn is produced using a process called open-end spinning. Repeatedly drawing a yarn stretched into the rotor produces open-end yarn. Open-end yarn can be produced from short fibers. Open-end yarns are different from ring yarns. Open-end yarns are limited to coarser counts. Open-end yarn is highly cost-effective because it is made using even the shortest cotton strands. The number of twists must be greater than ring yarns to assure integrity. As a result, it has a more branched (irregular) structure.
Ring yarns are known in the art as being produced from the long fibers of cotton. Ring yarn is divided into carded and combed cotton. The difference between the two yarns is due to the combing process. The combing process is the intensive process that feeds the machine the raw material (cotton) with the help of the combs in the machine, and thus the short fibers of the cotton are separated. Depending on the cotton used and the machine settings, 5-25% fiber can be extracted from the raw material. One difference of combed yarn made from carded yarn is that it is produced using longer fibers obtained after the combing process. Carded and combed yarn is frequently of higher quality than open-end yarn.
The boxes 24 are structurally substantially identical, and conventionally filled with many liters of chemicals, water, and/or dye. The boxes 24 serve different purposes and therefore may have chemicals that differ from box to box. A cross sectional view of one of the boxes 24 is illustrated in
Like the lead-in roller 281, the lead-out roller 282 guides the yarn over the edge of the open top container 25, and sets the yarn at a preferred approach angle towards the nip rollers 32 that follow.
The nip rollers 32 are pairs or sets of rollers between which the yarns pass and that apply pressure between themselves and to the yarn. In the case of dye range 20, the nip rollers 32 squeeze the yarn and pull the yarns through the dye range 20. Each time the yarns are immersed in a container 25 of a vat 24, the yarns are subsequently passed between respective nip rollers 32. The squeezing of the yarn between two rollers 32 removes much of the liquid and chemistry applied to the yarns in the preceding vat 24, and returns that liquid and chemistry back to the vat 24 from which the yarns just passed. The pressure between the top and bottom nip rollers 32 is adjusted predominantly through air pressure changes on cylinders that press the top nip roller 32 down onto the bottom nip roller 32, but sometimes additional weights are added to the top roller. The squeezing pressure of the nip rollers 32 can be in the range of 40 to 95 PSI and the preferred range is 60 to 85 PSI.
Each vat 24 frequently includes a heating element 34 within the container 25. Typically, heating element 34 includes a series of pipes that are also immersed in the chemistry or liquid within the container 25. These pipes are filled with steam when the range operator determines the need to heat the vat 24. This represents indirect steam heating due to the closed coil in the vat 24. Under normal conditions to best utilize the steam, wash boxes 24 are used with direct steam heating, while the dye boxes 24 are used with indirect steam heating. When steam is used for heating, it condenses in the vat 24 when used as direct heating. In the case of a dye box, the steam condensate may reduce the dye concentration, so heating is normally done indirectly via a closed circuit coil. The size or proportions of the open top containers 25 are a variable, with many different configurations throughout the world. Likewise, the size, placement, and number of the rollers before, within (immersion stage) and after are also a variable, with many different configurations throughout the world.
The method for dyeing the yarn according to the present invention comprises a series of stages.
First, in a pre-treatment (scour or prewet) stage 221, best shown in
According to the present invention, there is no need to heat the caustic pre-treatment box 241. According to the present invention, the circulation of caustic caused by movement of the yarn in the box 241 is an exothermic process and releases heat that heats the caustic solution up to 60 to 65° C. based on ambient conditions. A wetting agent may be used in the caustic formulation that is stable to the highly alkaline caustic pretreatment solution. Exemplary wetting agents are Primasol NF or Mercerol of Archroma. The concentration of wetting agent can be in the range of 1 to 7 grams/liter. The preferred range is 4 to 6 grams/liter in the pre-treatment box 241.
Next, in a scour rinsing (or caustic washing) stage 222, best shown in
The scour rinsing stage 222 that follows the pre-treatment stage 221 reduces or eliminates the caustic material and contaminants absorbed by the yarns during the pre-treatment stage 221 before the next stage of yarn treatment. The removal of excess caustic by rinse water can be tested by checking the pH in caustic rinse box 242 and controlling it to a pH of less than 11.8. When the next treatment is sulfur dyeing, then the pH in the rinse box should be in the range of 10.5 to 11because the preferred pH range of a sulfur dye box is 11.8 to 13.7. If the next treatment step is indigo dyeing, then the pH of the caustic rinse box 242 is controlled to under 11.4 because the preferred pH range of indigo dyeing according to the present invention is pH 11.4 to 11.6. The pH in the caustic rinse box 242 is set at a range below the pH of the immediately subsequent dye box in order to avoid improper pH conditions arising in the dye box. If sulfur dye is to be applied in dyeing stage 223, shown in
The oxygen of air and/or water oxidizes the dye and converts it to an insoluble form. The higher the amount of reducing chemicals, the slower the oxidation rate of sulfur dye. When the yarn passes through the squeezing rollers, the excess sulfur dye and other liquids are squeezed back into the dye box. After squeezing, the yarn carries some amount of dye and other liquids. The reduced dye keeps traveling towards the yarn core from the outer surface, potentially resulting in diffused dyeing. Excess usage of reducing chemicals is to be avoided to minimize dye travel towards the core. Reducing chemicals, such as glucose, sodium sulfide, sodium hydrosulfide, and polysulfide in the sulfur dye can be measured by testing the MV of the solution. There is a linear relationship between the amount of reducing chemicals in the dye solution and millivolts. The higher the amount of reducing chemical, the higher the millivolts, and vice versa. The reducing chemicals are used to compensate for the water added to dilute commercially available pre-reduced liquid sulfur dye. In the case of powder-based sulfur dyes which are insoluble, the reducing chemicals are needed based on the purity and strength of the chemicals and the strength and concentration of the dye to solubilize. The general ratio of dye to reducing chemical is 1:1.
The required concentration of reducing chemical changes based on whether powder sulfur dye or pre-reduced liquid sulfur dye is used. For powder sulfur dye, reducing chemicals are needed to solubilize the sulfur dye, while pre-reduced liquid sulfur dyes available in the market are already pre-reduced and solubilized, so at the stage of application on cellulosic yarn the required reducing chemicals are only that amount required to compensate for the water used for the dilution of dye.
As the yarn twist increases, the compact region in the yarn structure increases and dye penetration reduces. The yarn twist can be mapped with twist multiplier (TM), which is the result of the twist per inch divided by square root of yarn count (English Count). A TM in the range of 3.7 to 5.4 for ring and open-end cellulosic yarns may be used. The preferred range is 4.5 to 5.4 TM. To achieve the best ring dyeing effect, the yarn TM should be in the above range. The higher the yarn TM, the higher the ring dyeing and lower the dye penetration.
Sulfur black shade specifications according to the present invention are shown in
Conventional dyeing methods may also use high concentration of caustic as a pretreatment, and include sulfur dyeing with one or more dye boxes, longer immersion times, higher skying times, and use of wetting agents in the sulfur dye chemistry. Table 1 shows clearly that even after the usage of caustic for pretreatment there is no ring dyeing with conventional methods. The disclosed invention produces good ring dyeing by reducing the immersion time of the yarn in the dye vat, reducing the skying time for sulfur-dyed yarn, and utilizing full skying time for indigo dye.
Table 2 contains data for sulfur application pursuant to the disclosed invention. Table 2 contains data on the yarn, the TM, the type of sulfur dye used, the speed of the range and the concentration of the caustic. Also included is data on the caustic temperature, caustic immersion time, skying, number of wash boxes and number of sulfur dye boxes. The skying time, whether a steamer was used, the shade desired, the pH of the sulfur dye. MV, and use of wetting agents is disclosed.
Examination of all yarns dyed pursuant to Table 2 are shown. Yarn tests 1-5 did not achieve the ring dye effect because one or more of the herein disclosed parameters was not followed as explained in Column AB.
If indigo is to be applied, the dyeing stage 223 includes immersing open-end yarn into and passing the yarn through a plurality of indigo dye boxes 243, each box 243 containing indigo dye. Up to 12 vats 243 containing indigo dye may be used to achieve a desired indigo color. If indigo is to be applied, the yarns proceed from the caustic rinse tank to an indigo dye tank as best shown in
If the yarn is to have an indigo dye applied, then indigo dyeing stage 224 is best shown in
The indigo shade can be dyed in range of 0.5% to 7% as per the fashion requirement as an individual indigo shade or with sulfur dye combination of bottoming or topping or bottoming and topping both.
The MV of indigo dye vats is in the range of −680 to −780, and the preferred range is −715 to −725. In the case of indigo the redox potential is measured for the presence of free sodium dithionite (Sodium hydrosulfite, sometimes known as “Free Hydro”. The Free Hydro is the availability of excess sodium hydrosulfite in the indigo solution which keeps the indigo dye in fully reduced form. If the ‘Free Hydro’ reading falls below 0 gram/liter, then the amount of sodium hydrosulfite in the indigo solution is less than the amount required to keep indigo in reduced form. The higher the amount of ‘Free Hdro’, the reading represents excess hydrosulfite. The higher the presence of Free Hydro in the indigo solution, the slower the air oxidation of indigo when the yarn is skyed after leaving the indigo vat (after squeezing in nip rolls) and the dye penetration increases. So, to restrict the indigo dye penetration and to keep the indigo dye in a stable form in the dyeing vats, the amount of ‘Free Hydro’ is optimized and maintained in the range of 0.05 to 0.4 gram/liter, and the preferred range is 0.05 to 0.25 gram/liter.
Examination of yarns dyed according to the disclosed invention as set forth in Table 4 established that the ring dye effect had been achieved.
The dye vats 243 are large tanks containing a dye solution or dye chemistry, such as sulfur black, sulfur brown or indigo, within which the yarns 10 pass over a series of rollers 30. The dye vats 243 are typically over 250 gallons each, with some as large as 700 gallons. The yarn passes over or under rollers in each vat 243 to immerses the yarns 10 in the dye chemistry.
After the dyeing step, the thus dyed yarn moves to a skying stage 224 for skying the yarn, open-end yarn or the ring yarn, for 1 to 30 seconds, preferably 1 to 18 seconds when sulfur dyeing. We have found that for sulfur-dyed yarns, the skying time should be reduced from the skying time conventionally utilized. Skying allows the dye to oxidize with the help of oxygen of air and thus become insoluble, so that it does not dye the yarn. For indigo dyeing, air oxidation is preferred. The skying time can be in the range of 30 to 140 seconds based on the arrangement of the guide rollers and the speed of the range 20. The longer the skying time, the longer the exposure to the oxygen of air and thus oxidation of the indigo dye.
Following the skying stage 224, the yarns of the disclosed invention move to washing stage 225. The yarn is washed with non-contaminated water or natural water at ambient temperature based on geography for between 6 to 40 seconds in one or more dye rinse vats (or wash boxes) 245 based on the size of the dye rinse vats 245, the arrangement of the guide rollers 30 in the dye rinse vat 245, and the speed of the range 20. Ambient temperature is preferred, because at higher temperatures the dye has increased mobility and travels toward the core of the yarn. According to the disclosed invention, the number of the dye rinse vats 245 may vary from 1 to 5. The dye rinse vats 245 remove loose dye from the yarns. This dye rinse reduces the contamination loose dye could impose on later processes, as well as reduces the “bleeding” of color a consumer may encounter. The skying stage 224 immediately after the indigo dye box 243 oxidizes the dye and stops travel towards the core of yarn 10. The rinse step immediately after the sulfur dye box oxidizes the sulfur dye with the help of oxygen from non-contaminated natural water. As noted, we prefer that skying be minimized with sulfur dye due to the higher temperature of the sulfur dye bath and the increased mobility of the sulfur dye as a consequence. Also, the rinse step removes unfixed dye from the yarn surface.
In order to achieve the ring dye effect for sulfur dyes, the disclosed invention utilizes immediate treatment of the sulfur-dyed yarn with the oxygen of fresh (i.e., non-contaminated) water at room temperature to oxidize the dye and restrict travel of dye molecules. We prefer room temperature water because higher temperatures tend to increase dye mobility into the core. We have found that restricted dye immersion and air oxidation time followed by quick washing to oxidize the sulfur dyes and remove unreacted dyes from yarn achieves good ring dye effects. For indigo dyes, full skying time is utilized to allow the dye to oxidize. Reduced skying time for sulfur dyes typically requires that the path of the yarn through the dye range be modified, usually by altering the number or path of the rollers the yarn traverses upon exiting the dye box 243, as best shown in
Fresh water is continuously supplied to the dye rinse vats (or wash boxes) 245 immediately after the sulfur dye box 243. This provides fresh oxygen to oxidize the reduced dye. Oxidized dye is insoluble and gets fixed on the cellulosic yard. The oxidized dye does not travel towards the core of the yarn because it is not in a water-soluble form. The lower temperature helps reduce dye travel, because at higher temperature the dye travel rate increases.
The immediate exposure of sulfur-dyed yarns with fresh incoming water also applies a thermal shock to the dyed yarn, and the temperature of the dyed yarn rapidly achieves room temperature. At or about room temperature, the rate of travel for the dye molecules is minimized and hence the ring dye effect is preserved.
The water in the wash boxes needs to be replenished continuously, so that fresh oxygen can be supplied to oxidize the sulfur dye. The rate of the water supply can be optimized in the range of 1 to 4 liter/kg of water, and it can be optimized by testing the pH of water in the wash box 245 and maintaining the pH under 12.5. A series of wash boxes 245 equipped with squeezing rollers 32 may be arranged to remove unreacted dye from the yarn. The number of wash boxes 245 are a minimum of one and a maximum of three. The wash boxes 245 can be more than 3 but that number may be unnecessary. More wash boxes consume more water and electricity to drive the yarn through the range 20, and thus increase costs.
The combination of restricted dye immersion time for the yarn, and restricted dyed yarn exposure time to air followed by immediate water rinse to oxidize the dye on the yarn and remove unreacted dye restricts the sulfur dye to the ring form on the outer circumference of the yarn, and represents an important achievement of this invention.
The wetting agent in the sulfur dye helps the dye to penetrate to the core of the yarn, which for this invention is undesirable. Hence the wetting agent or penetrating agents should be removed from the sulfur dye formulation or not used according to the disclosed invention.
In some conventional dyeing, there are steamers used with a temperature range of 100 to 105° C. immediately after the sulfur dye box 243. Steamers are supplied with saturated steam which provides temperature and moisture that helps the dye molecules to penetrate more and react better with cellulose reactive sites and make strong chemical bonds that restrict the treatment with laser and chemicals. The moisture provides a vehicle and increased temperature that increases the dye travel rate. Accordingly, with the help of a steamer, the sulfur dye travels towards the core of the yarn 10 and makes a strong bond with cellulose. This is undesirable according to the present invention. According to the present invention, the use of the steamer is eliminated after the sulfur dye box 243. Elimination of the steamer also reduces costs.
One important differentiator of the present invention is the use of only one (i.e., single) sulfur dye box 243. When cellulosic yarn is subjected to more than one dip of sulfur (one dip represents a combination of immersion in the dye box and squeezing with pressure rolls-nip rolls) the dye penetration increases towards the core. The cellulosic yarn when dyed once with sulfur dye, turns alkaline, and it carries caustic, reducing chemicals (like sodium sulfide/glucose), and sulfur dye inside the yarn which is a supportive environment for sulfur dye to remain in a stable condition. Should such yarn go to a second sulfur dye box, the sulfur chemistry plays the same role. The alkaline environment helps the dye to travel towards the core of the yarn, so it does not result in ring dyeing. With multiple sulfur dye boxes, the dye cannot be restricted to the outer periphery of the yarn. Use of more than one sulfur dye box without strong chemical oxidation between two consecutive sulfur dye boxes 243 cannot restrict the dye to the outer surface of the yarn. Such additional dye boxes increase dye penetration to the yarn. Conventionally one to six sulfur dye boxes are used. In the case of the present invention, only one sulfur dye box is preferred or necessary to dye the yarn.
We have found that one sulfur dye box with the recommended immersion and skying conditions achieves perfect ring dyeing as it restricts the dye to the outer surface of the yarn. This yarn is not subjected to a second dip of sulfur dye, so dye penetration is restricted. While we prefer that only one dye box to be used, more than one sulfur dye box can be utilized provided there is strong chemical oxidation and washing intermediate two consecutive sulfur dye boxes 243.
The dye on the yarn can be completely oxidized by oxygen from freshwater (by water wash with non-contaminated water) and/or by chemical oxidation (with the help of oxidizing chemicals such hydrogen peroxide in neutral to acidic pH). When oxidizing chemicals are used, they should be removed from the yarn by washing with water before the next sulfur dye box because if the yarn carries these oxidizing chemicals to the sulfur dye box, it can make the dye box unstable. Also, it leads to increased consumption of reducing chemicals in the sulfur dye box as the dyeing progresses. The use of chemical oxidations is practiced by the denim industry. According to the present invention, chemical oxidation can be done to replace freshwater oxidation (with the use of oxygen in freshwater). Chemical oxidation increases the cost of manufacturing due to the higher cost of chemicals compared to water. The concentration of hydrogen peroxide (of 50% strength) can be used in concentration 1 to 10 gram/liter with a weak organic acid to maintain the pH acidic to neutral in range of 4 to 7.
The techniques of sulfur dye application can be used for all types of fashion requirements of denim dyeing, including sulfur dye bottoming and indigo dye topping on the same yarn, indigo dye bottom application and sulfur dye topping application, and self-shades of sulfur dye without application of indigo dye.
The washing stage 225 is followed by drying stage 226. The drying stage 226 utilizes drying cans 38. After the yarns pass through the last immersion in the washing stage 225 and the respective nip rollers 32, the yarns are then dried before storage or further processing. The goal in drying of the yarns is typically to match the moisture in the yarns with the humidity in the ambient air.
Although a high concentration of caustic may be used as pretreatment in conventional dyeing, there is no ring dyeing as shown in Tables 1 and 3. The method according to the present invention uses differentiators along with caustic pretreatment in sulfur and/or indigo dyeing so that good ring dyeing is achieved as shown in Tables 2 and 4.
When the yarn is first pretreated with caustic and then sulfur is used in bottoming or topping of indigo, the sulfur shade can be applied in the range of 0.1% to 35% (considering 100% strength of sulfur dye) of the weight of the warp yarn. Based on the % shade of application, the dye box concentration is determined. The same sulfur dye can be applied in the shade range of 0.1% to 35% (considering 100% strength of dye) of the weight of the yarn for Self Sulfur Shades (without the combination of indigo on top or bottom). Sulfur Black is more popular and at the same time, other shades can also be dyed with the same innovation in the same above range. The indigo shade can be dyed in range of 0.5% to 7% as per the fashion requirement as an individual indigo shade or with sulfur dye combination of bottoming or topping or bottoming and topping both.
Further, as illustrate in
The foregoing description of the exemplary embodiments of the present invention has been presented for the purpose of illustration in accordance with the provisions of the Patent Statutes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments disclosed hereinabove were chosen in order to best illustrate the principles of the present invention and its practical application to thereby enable those of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated, as long as the principles described herein are followed. Thus, changes can be made in the above-described invention without departing from the intent and scope thereof. It is also intended that the scope of the present invention be defined by the claims appended thereto.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/462,699 filed Apr. 28, 2023, by Costin, Jr. et al., which is hereby incorporated herein by reference in its entirety and to which priority is claimed.
| Number | Date | Country | |
|---|---|---|---|
| 63462699 | Apr 2023 | US |
