Multi-stage apparatus for dyeing fabrics and yarns with indigo and other vat dyes in inert environment

Abstract

The description provides an apparatus for dyeing a textile support, the apparatus comprising a single cylinder having, sequentially arranged within therein: a first cavity having a watertight function between the surrounding environment and the cylinder; a first internal partition wall immersed in the lower portion of the dye liquor in the first cavity to facilitate the watertight function; a first dyeing separation chamber and at least one second dyeing separation chamber, each dyeing separation chamber including at least one return roller for the textile support, at least one dispensing device for dispensing dye liquor onto the textile support, and at least one extrusion device; a second cavity containing dye liquor having a watertight function between the cylinder and the surrounding environment; and a second internal partition wall immersed in the lower portion of the dye liquor in the second cavity to facilitate the watertight function. The dyeing apparatus further includes: at least one cover that closes the cylinder at the top and watertightly isolates the dyeing compartment from the surrounding environment; a motorized extrusion and traction device configured to pull the textile support out of the cylinder and remove excess liquid therefrom once it leaves the cylinder; a hydraulic system for feeding the dye liquor into the dispensing device and the cavity; one or more devices for blowing air, designed to increase the oxidation level of the textile support once it leaves the cylinder; at least one ultrasonic generator designed to increase the bath dyeing effect of the dye liquor; and a device for heat-conditioning the dye liquor to further enhance the coloring performance.

Description

[0001] The present invention relates generally to a dyeing apparatus, and in particular to a multi-stage apparatus for dyeing yarns and fabrics with indigo and other vat dyes in an environmentally sustainable manner. More particularly, the present invention relates to a multi-stage apparatus for continuous dyeing of denim fabrics and / or warp chains of weft-warp and knit fabrics.

[0002] The present invention also relates to an improved implementation of a dyeing method which makes it possible to obtain improved simple and reasonable quality, ecological and economic results compared to the prior art. More particularly, the present invention relates to an apparatus which is very simple, reasonable, advantageous and economical and which can be used in one or more types of continuous dyeing production lines and machines for open-width, rope, ring systems, or discontinuously for warp chains of denim fabrics dyed with indigo and other vat dyes in an inert environment with bath ecologies with low and / or high concentrations and low or high temperatures. For a clearer description and easier understanding, the present invention will be described by way of non-limiting example, with particular reference to the continuous dyeing of warp chains of denim fabrics in open-width systems.

[0003] Denim is a particular fabric for making jeans, garments, which are popular because of the association with images of youth, sport, rebellion, ease and happiness. In fact, they are garments for everyone and for any activity. It is estimated that worldwide approximately five billion jeans are produced each year, which makes denim the leader of the largest scale fabric production worldwide.

[0004] The success of the denim and blue jeans combination derives from the dyeing of the warp of this fabric with indigo. Indigo is one of the oldest dyes, which is not easily applied on cotton, having a low affinity for cotton, but which has unique characteristics which give the fabric, and therefore the finished garment, a long-lasting appearance which is shiny and pleasing. In fact, the value of blue jeans lies in their typical navy blue shade, which gradually assumes a lighter shade as a result of repeated washing operations, until a bright blue is obtained. To the best of our knowledge, no other dye has similar properties to indigo. After a number of washing operations, other types of dye tend to dirty grey, or to dye white weft yarns in an ugly blue / grey colour. This particular characteristic, together with the image of a garment which is worn over time, in the form of wear in the most exposed places and with a flexible effect on the body of the person wearing it, constitutes the attraction of blue jeans, which is now and will always be the most popular garment item in the world in many respects, in terms of production and handling.

[0005] One of the characteristics that makes indigo dye unique is the particular dyeing method required for its application to cotton yarns. This dyeing method has remained almost unchanged since its synthesis, over 100 years ago, from the era of vegetable dyes. Due to its relatively small molecule and its low affinity for cellulose fibers, in order to be applied, indigo dye must not only be reduced in an alkaline (leuco) solution, but also needs to undergo multiple immersions, alternating with wringing and subsequent oxidation in air. In fact, to obtain medium or dark shades, it is necessary to pass the yarn through a first dyeing operation (immersion, wringing, oxidation) immediately followed by the same operation in a loop, the more loops the deeper the shade and the higher the color stability required.

[0006] This particular dyeing method, which is typical of indigo, shows the great importance of respecting certain fundamental parameters related to the number of immersions in tanks and oxidations. This is to allow the dye to be impregnated and evenly distributed in the skin or surface layer of the yarn ("ring dyeing"), and, after complete wringing, to be thoroughly oxidized before entering the next tank, to be able to "build up", i.e. intensify the color shade.

[0007] However, in addition to being influenced by these parameters, the continuous dyeing with indigo is also influenced by many other factors, which involve various physical-chemical environments specific to each individual system and the environmental conditions in which the system itself is installed, such as the temperature and relative humidity of the air, the coolness, the altitude, etc. In addition, different dyeing conditions (such as the number of tanks, their capacity, the pick-up, the type and circulation speed of the dye bath, the type and accuracy of the system for automatic dosing of the dye, sodium sulfite and caustic soda, etc.) and different dye bath conditions (such as temperature, concentration, pH, redox potential, etc.) not only have a decisive influence on the result of the dyeing (such as the intensity, stability, skinness of the shade, etc. stronger or weaker) but, in combination with the various operations of pre-treatment (milling, pre-dyeing, etc.) and post-treatment (loop dyeing, fixation, etc.), also greatly contribute to determining the final appearance of the garment after its normal passage through various washing and finishing treatments. It should also be specified that, contrary to other classes of dyes, whose affinity for cotton increases with the increase in temperature, in the case of indigo, the affinity and the intensity of the color, caused by the higher skinness of the dye, increase with the decrease in temperature.

[0008] Continuous dyeing of warp chains for denim fabrics is primarily carried out according to two systems: the so-called "rope" system and the so-called "flat" or "wide" system. Although these two systems are substantially different from each other, they are combined in the case of indigo dyeing, using the same dyeing method, which basically consists of three repeated operational stages: impregnating the yarn with reduced dye, squeezing to remove excess dye liquor, and oxidizing the dye by exposing the dyed yarn to air.

[0009] Typically and traditionally, in both rope and wide-width systems, indigo dyeing is used for the warp chains of denim fabrics in open vats and at low temperatures. Specifically, in both systems, the facilities for continuous indigo dyeing usually consist of 3-4 pretreatment vats (absorption, soaking, fulling, pre-dyeing, etc.), 8-10 vats for actual dyeing, and 3-4 post-treatment vats (over-dyeing, fixing, washing, etc.). All vats are equipped with pneumatic extrusion units to remove excess dye liquor, and the dye vats also have a set of cylinders for exposing 30-40m of yarn to air to oxidize the dye.

[0010] The dye liquor is of the open type, and in the "flat-width" system, each has a liquor capacity varying between 1000 and 1500 liters, containing approximately 4-6 meters of yarn. These quantities of dye liquor determine the total volume of dye liquor circulating in the system, which can therefore vary from approximately 8000 to 15000 liters. The dye liquor contained in each vat is continuously recirculated to ensure uniformity of concentration within each vat. This circulation is typically carried out using various known piping systems equipped with high-capacity, low-head centrifugal pumps to avoid harmful turbulence. The movement of the dye liquor causes a constant replacement of the surface portion of the liquor itself in contact with air; since the vats are open at the top, this leads to oxidation. The oxidation of the dye liquor results from the continuous depletion of the reducing agents contained within, namely sodium sulfite and caustic soda; the more this occurs, the higher the temperature of the dye liquor becomes.

[0011] Therefore, it involves multiple oxidation stages, which contribute to the depletion of the dye liquor itself (sodium sulfite and caustic soda) in a much larger way than described above. These oxidation stages are an integral part of the dyeing cycle, and in fact, they consist of exposing approximately 30-40 meters of yarn impregnated with the leuco dye to air between one of the 8-10 dyeing vats in the system. In total, the yarn is thus exposed to air for several hundred meters throughout the dyeing system.

[0012] Based on this, the amount of sodium sulfite and caustic soda that have been oxidized and destroyed must be continuously replenished to maintain the dye solution under optimal chemical conditions, maximizing dyeing performance and ensuring consistent and reproducible results. These continuous additions to the dye solution constitute a significant economic cost, increasing its salinity, causing dyeing problems, and significantly contaminating the final wash water.

[0013] It should be understood that, under conditions of concentrated leuco dyeing, the dye liquor must also have a continuously added dye, the amount of which must reach the desired color intensity. For the continuous, automated metering of indigo dye, sodium sulfite, and caustic soda, various systems can be used, such as metering pumps, weighing, volumetric, and mass systems, all of which are known because they are commonly used in other textile processing. It should be understood that the larger the volume of the dye liquor, the longer it takes to achieve the chemical / dyeing equilibrium required for the new dye liquor to consistently reach the same color intensity. The response time to any corrective intervention will be equally long, and this does not contribute to operability, process automation, repeatability, and especially, obtaining the desired quality.

[0014] Another distinctive feature of indigo dye is that the dye baths containing this dye are never replaced, except to alter the color intensity. As previously mentioned, instead, the dye baths containing indigo are continuously reused, with the addition of sodium sulfite, caustic soda, and the dye to maintain their chemical / dyeing equilibrium constant. Therefore, for each different concentration of baths in use, each dyeing system has a container with the total capacity of all baths.

[0015] For quality purposes, it is paramount to maintain the physicochemical conditions of the dye liquor consistently throughout the entire batch of yarn dyeing. On average, this time varies between 5 and 30 hours, depending on the yarn chain length and dyeing speed. However, despite continuous mechanical and hydraulic improvements to the dyeing system, and the aid of sophisticated control and metering systems, continuous indigo dyeing remains a complex operation due to the large volume involved and the many reasons mentioned above, which individually or in combination produce undesirable changes to the dye liquor conditions.

[0016] However, besides the factors mentioned above, in a flat-width dyeing system, which is preferred over a rope system for many advantages, the yarn length through the production line, i.e., the dyeing and sizing machine, can reach approximately 500-600 meters. This is a very reasonable dyeing system; however, it has economic disadvantages due to the amount of yarn lost with each batch change. In fact, all of the aforementioned amount of yarn, which constitutes the end of this batch, has been dyed and remains in the system after it stops, and must be considered waste because it has not been dyed evenly. Similarly, the same amount of yarn, which constitutes the beginning of a new batch and is connected to the end yarn, is replaced during the dyeing process (an operation performed at low speed for technical and safety requirements), has not been dyed evenly, and therefore must be eliminated.

[0017] However, denim, unfortunately, also stands out as one of the garments causing the worst environmental and social impacts within the entire apparel industry. The production cycle of blue denim, from cotton cultivation to the point of sale, requires extremely high levels of water and energy consumption, as well as the use of chemicals at various stages of production. Therefore, it is evident that the most significant contaminant and characteristic operation throughout the entire denim fabric production cycle is the continuous dyeing of the warp chains with indigo dye and / or other reducing dyes before the warp chains are placed on the frames used to produce the fabric. In fact, classic denim is produced by weaving pre-dyed cotton yarns. Specifically, only the warp yarns are dyed, while the weft yarns are used untreated.

[0018] Unfortunately, recurring economic crises, trade wars with embargoes and tariffs, various social and political problems, and pandemics around the world have contributed to widespread poverty and economic recessions, leading to decreased purchasing power. These factors, along with others, particularly the growing demand for eco-sustainable products, have inevitably led to declining profits and thus necessitated significant changes to the denim production line. Furthermore, denim has undergone continuous evolution from simple, highly standardized workwear before it became a major fashion item, constantly demanding diversification in its production. It is now produced in various weights, with different weaves, using yarns of various counts made from cotton or blends and other fibers, in a wide range of colors, and with various final treatments; in short, it has become highly diversified. For these reasons, denim manufacturers must not only continuously increase and diversify the number of fabric types offered, but also manufacture them faster, in shorter lengths, and at lower prices, resulting in significantly reduced profit margins.

[0019] Never before, in such a globalized context, innovation that reduces energy, chemical, and especially water consumption, and consequently lowers production costs, has become a strategic imperative. This is crucial for maintaining or winning market position in the industry and overcoming competitive disadvantages. The innovation involved is less about the product or material itself and more about the production methods. Given the above, it is evident that denim producers now face an essential economic and ethical imperative to transform their production systems and innovate their traditional dyeing machinery in the lowest possible cost way to reduce energy, water, and chemical consumption and minimize waste. In other words, denim producers need to do everything possible to provide newer, lower-cost, and more economical products that are also ecological and environmentally sustainable—a topic of increasing global concern. Regarding the ecological aspects, it is not impossible that international laws mandating significant reductions in consumption and adherence to precise standards aimed at protecting health and the environment will soon be in place; in fact, many consumer protection agencies have already called for and consider it desirable.

[0020] In the specific field of continuously dyeing warp chains of denim fabrics with indigo, dyeing equipment that partially meets the aforementioned requirements has been produced. However, these dyeing devices, due to their complexity and high cost, have so far been produced in small quantities, as described in patent documents EP 1771617B1 and EP 1971713 B1 and patent document EP3464702 A1, all under the same applicant. Dyeing equipment operating under these conditions, i.e., in an inert environment, preferably in nitrogen, effectively eliminates many problems of conventional dyeing systems. Compared to conventional dyeing systems, they not only have the advantage of reducing the number of dye baths, thus reducing required space and waste, but also, in particular, a significant reduction (50% to 80%) in the consumption of caustic soda and sodium sulfite, as they can operate with higher concentrations of bath solution. Furthermore, significant savings in washing water are achieved due to better dye fixation on the yarn. Moreover, in an inert environment (preferably under nitrogen), the chemical reduction of indigo is complete and total, and the leuco form is broken down into particles of nanoscale size, which improves its dyeing ability.

[0021] Compared to traditional air-based dyeing systems, this increased leuco dyeing capability allows for better penetration and fixation on the fibers, resulting in favorable dyeing outcomes in terms of stability, strength, and brightness—differences that enhance the quality of the final fabric. Furthermore, the technology demonstrates that dyeing with sulfur-based dyes, particularly those used for denim colors, is the most energy-intensive because the dyeing process is carried out at high temperatures, especially with black dyeing, which is also used for pre-dyeing and over-dyeing, providing better colorfastness. This can be visually assessed at approximately 40%, with significantly improved fixation levels and better brightness compared to dyeing performed on conventional machines.

[0022] Therefore, considering the many motivations previously given, even if the dyeing equipment shown in the aforementioned patent documents partially achieves these motivations, it is logical that the field of denim warp dyeing needs new machines with more rational and simpler structures. Most importantly, these machines should be able to operate at a higher standard and more economically with the least possible investment. It is evident that, to meet these requirements, it is necessary to have new dyeing equipment that, compared to the equipment according to the aforementioned patent documents, not only simplifies the structure to reduce initial investment but also allows operation with new dyeing methods and significantly reduced dye liquor volumes, thereby substantially reducing production costs.

[0023] Based on the concepts in the aforementioned patent documents, document WO 2020 / 053677 A1, also under the same applicant's name, describes a dyeing apparatus. This dyeing apparatus is integrated into a multifunctional, eco-friendly, and economical system for discontinuously and reversibly dyeing fabrics (preferably tannin) using indigo and other reducing dyes in alternating stages and an inert environment. By moving the fabric in both directions, the dyeing apparatus autonomously performs the entire operating cycle (pretreatment, dyeing, and posttreatment) and may also perform multiple dyeing stages.

[0024] On the other hand, the object of the present invention is to provide, in a simplified embodiment, a multi-stage device for the continuous or discontinuous eco-sustainable dyeing of warp chains of tannin in flat, rope, and loop systems with indigo and other reducing dyes in an inert environment with minimal economic input. This device not only addresses the shortcomings of dyeing systems according to the prior art, but also improves their performance and operational flexibility in an extremely simple manner, and significantly reduces production costs.

[0025] In detail, the object of the present invention is, in a simplified embodiment, to provide a multi-segment device for dyeing warp chains of denim fabrics, which, in one or more instances, can be used continuously or discontinuously in the dyeing process with indigo and other reducing dyes, and which can reduce the number of vats typically used in dyeing production lines according to the prior art, with corresponding ecological and economic advantages, and which can also be operated to reduce waste in each batch change.

[0026] Another object of the present invention, in a simplified embodiment, is to provide a multi-segment device for dyeing warp chains of denim fabrics, which uses indigo and other reducing dyes, enabling unique dyeing with high-concentration baths, and also at low and / or high temperatures.

[0027] Another object of the present invention, in a simplified embodiment, is to provide a multi-segment device for dyeing warp chains of denim fabrics, which allows dyeing with indigo and other reducing dyes under technically optimal conditions, and which makes it possible to significantly increase the amount of dye fixed on the fibers compared to dyeing systems according to the prior art.

[0028] Another object of the present invention, in a simplified embodiment, is to provide a multi-segment device for dyeing warp chains of denim fabrics, which allows dyeing with indigo and vat dyes with a greatly reduced dye liquor volume, fed in an inert environment via a front-side cascade sprayer into the "NIP" of the accompanying yarn cylinders to enhance the bath / fiber exchange ("NIP" means the point of tangency between each cylinder of the accompanying yarn and the yarn itself at the point where the yarn enters around the cylinder).

[0029] Another object of the present invention, in a simplified embodiment, is to provide a multi-segment device for dyeing warp chains of denim fabrics, which, through operation with a dye liquor of greatly reduced volume, enables rapid achievement of dyeing equilibrium of the dye liquor and allows for a significant reduction in its various chemical components (caustic soda and sodium sulfite), energy consumption, and production costs. Furthermore, the dye liquor can be restored in a conventional plastic tank for reuse, resulting in a significant reduction in investment costs compared to large-capacity storage containers.

[0030] Another object of the present invention is to provide a multi-segment device in a simplified embodiment that makes it most convenient and easy to operate and maintain.

[0031] Another object of the present invention is to provide, in a simplified embodiment, a multi-stage device that uses indigo and other reducing dyes, for use in continuous or discontinuous dyeing production lines for the warp chain of tannin, and also for continuous or discontinuous dyeing production lines for warp-weft and knitted fabrics.

[0032] Another object of the present invention, in a simplified embodiment, is to provide a multi-segment device for dyeing warp chains of denim fabrics, which, under economically advantageous conditions, utilizes a system for cooling the dye bath and an ultrasonic generator to further enhance coloring performance when dyeing with indigo and vat dyes.

[0033] Another object of the present invention is to provide, in a simplified embodiment, a multi-segment device for dyeing warp chains of denim fabrics, which can be operated to increase the current possible production variables.

[0034] Another object of the present invention is to provide, in a simplified embodiment, a multi-segment device for dyeing warp chains of denim fabrics, which, for dyeing with indigo and other reducing dyes, allows for an increase in the level of dye fixation on the fibers and a reduction in the consumption of wash water, thereby contributing to environmental sustainability.

[0035] These objectives according to the invention are achieved using the multi-stage dyeing apparatus described herein. To achieve these objectives, a series of studies and experiments were conducted, which fortunately led to a new, original, and innovative multi-stage apparatus for dyeing warp chains of denim fabrics. This apparatus not only fully meets the aforementioned requirements but also enables very high coloring performance through the application of a novel multi-stage dyeing method. Essentially, this new apparatus for dyeing with indigo and other reducing dyes in an inert environment, preferably under nitrogen, differs structurally from all known types of dyeing apparatus in that it operates with a significantly reduced volume of dye liquor, as it does not use full-capacity tanks and prolonged yarn immersion, but instead employs a new multi-stage dyeing system with spraying. Furthermore, its structure is very simple, being a single piece, and all developed on a flat-width basis.

[0036] Regarding multi-stage dyeing, it is possible to describe this new and novel dyeing system in detail, as it has been discovered and experimentally demonstrated that, under nitrogen, indigo dye is continuously fixed and strengthened after each immersion and / or spraying operation, even without the usual intermediate oxidation stage required in air in conventional systems. The first condition for this to occur is that, after each stage, the previously leuco-impregnated yarn does not provide interstitial dye liquor to aid in bath / fiber exchange. The second condition for this to occur is that, after eliminating the interstitial dye liquor, the yarn is held in an inert environment for a certain period of time for leuco-impregnation, for the diffusion / fixing dye, etc., for each subsequent immersion or spraying operation.

[0037] The possibility of adopting this new and important operating method enables the development of new and original multi-stage equipment for dyeing warp chains of denim fabrics in an inert environment, preferably under nitrogen. This equipment is completely different from, and is greatly simplified compared to, existing dyeing equipment in terms of design, structure, and operation. In particular, in this new and original multi-stage dyeing equipment, as with the dyeing equipment according to the aforementioned patent documents, it operates in an inert environment; the traditional dye bath, which is completely filled with dye liquor, is replaced by a single bath with almost no dye liquor; each stage is equipped with cascaded sprayers, improving dyeing performance; and most importantly, greatly reducing the volume of dye liquor.

[0038] This new multi-stage apparatus for staining in an inert environment not only fully meets the aforementioned expectations but also significantly improves the results and claimed advantages of the staining apparatus according to the aforementioned patent documents. In fact, unlike the staining apparatus according to the aforementioned patent documents, which is very bulky and includes, in addition to one or two dye tanks with large volumes of dye solution, separate and / or vertically elevated chambers for diffusion / fixation of leuco pigments, the multi-stage staining apparatus according to the invention features a revolutionary structural design that is extremely simple and extends entirely flat, achieving the same function more concentratedly and rationally through the application of a new and improved staining method in a single tank, offering additional advantages and improved coloring performance.

[0039] In essence, the apparatus for dyeing in an inert environment according to the aforementioned patent documents consists of one or two immersion tanks, each with internal partitions placed at the yarn inlet or outlet. In the first tank, which has a large dye liquor capacity and is also watertight, the yarn is immersed in the dye liquor for an extended period. After being forcefully squeezed by a pneumatic pressure padding machine, the yarn then enters a second compartment, typically in the form of a vertical chamber with an airtight side door or opening, where the yarn remains for a certain period to allow for diffusion and fixation of the leuco pigment absorbed by the yarn. Subsequently, the yarn leaves or enters the second tank, with a dye liquor and immersion capacity lower than or the same as the first tank, for a second immersion. The second tank is also watertight. Finally, the exiting yarn is forcefully squeezed again by a second pneumatic pressure padding machine for an oxidation stage on a set of cylinders placed in the air. In practice, these known types of dyeing equipment operate with one or at most two immersions and therefore have little or no dye enhancement.

[0040] As described above regarding the specific dyeing methods required for indigo dye, the first dyeing operation is followed by various over-dyeing operations, with a relatively low amount of dye enhancement specified after each of these operations, especially because indigo has a low affinity for cotton fibers. Therefore, in order to significantly improve the coloring performance of the aforementioned known types of dyeing equipment, it is necessary to develop a new type of dyeing equipment that can perform multiple over-dyeing operations and thus has multiple color enhancements in order to obtain strong color intensity.

[0041] According to the multi-stage dyeing apparatus of the present invention, from a system perspective, it is preferably based on the attached... Figure 1 The embodiment shown has three staining segments and can be produced, but it can also be produced according to other embodiments ( Figures 2-8The invention is created using the concept of operating in an inert environment, as shown in the aforementioned patent documents, with the yarn inlet and outlet being watertight. Structurally and functionally, the multi-stage dyeing apparatus according to the invention differs fundamentally in another respect. Despite its simplicity, this not only makes it extremely economical but also adds improved dyeing performance beyond the aforementioned claimed advantages, as well as providing further substantial improvements in quality, administration, and economy. This has practically become possible due to the advantageous findings described above, enabling the use of innovative multi-stage systems for dyeing by spraying. These multiple dyeing operations contribute to a significant increase in the amount of dye fixed to the yarn by affinity.

[0042] In fact, it has been found that under nitrogen, unlike dyeing systems in air according to the prior art, the yarn does not need to be immersed in the dye bath for a long time, because the dye bath sprayed in each dyeing segment remains in a leuco state in the inert environment, allowing it to continue to diffuse and fix onto the fiber. It should be understood that these multiple dyeing operations must be spread by lightly squeezing the yarn to refill the gaps in the dye bath, thus allowing for further dye enhancement. This particular feature ensures that the device according to the invention has its numerous enhancements, resulting in significantly superior coloring performance compared to the device according to the aforementioned patent documents.

[0043] The multi-stage dyeing equipment according to the present invention can be used as a single unit or multiple units in production lines for continuous indigo dyeing of warp yarns in various flat, rope, and loop systems, offering significant advantages. Compared to the equipment according to the aforementioned patent documents, it greatly simplifies the complexity of the structure and significantly reduces its cost. Furthermore, in addition to the same claimed advantages as the equipment according to the aforementioned patent documents, this equipment advantageously and significantly reduces the volume of dye liquor and thus its various chemical components, as well as the consumption of energy and water, resulting in a substantial reduction in production costs.

[0044] The multi-stage dyeing apparatus according to the present invention is the result of experience and new experiments that overturn the dyeing methods described in the aforementioned patent documents, thereby enabling the dyeing operation to be performed ideally for each dyeing operation, i.e., with the smallest possible dye liquor volume to achieve the maximum bath / fiber contact time. In fact, for this particular industry, this represents a technological and ecological turning point, allowing us to avoid facing the future with current technology. Compared to the system described in the aforementioned patent documents, the dye liquor volume indication is reduced by approximately 70% in this new system, and therefore, for the same circulation pump, the bath / fiber exchange is at least four times greater, thus ensuring improved dyeing while significantly reducing the time required to reach chemical equilibrium. Similarly, the capacity of the recovery / storage container for reusing the dye liquor is reduced, allowing the use of conventional plastic tanks.

[0045] The aforementioned advantages are achieved because, in addition to greatly reducing the volume of dye liquor through very short bathing operations in the initial and final cavities, its main purpose is to act as a hydraulic seal in the multi-stage dyeing apparatus according to the invention, where the yarn is no longer dyed during prolonged immersion in the dye liquor. Instead, the yarn is dyed by constant and uniform spraying of dye liquor directly into one or more lower cylinders in a "NIP" configuration, i.e., at the point of maximum hydrodynamic performance and therefore with maximum bath / fiber exchange, the lower cylinders accompanying the yarn in an inert environment in each individual dyeing segment that can constitute the apparatus. According to the new reinforcement system, these dyeing segments are separated from each other by simple extruders (by weight), wet product to wet product. In this regard, for the dyeing of yarns in ropes and fabrics, given their lower permeability compared to conventional flat-width yarn pads, it is preferable to have different positioning of the internal accompanying cylinders to create paths that allow for alternating spraying of dye liquor on both of their surfaces.

[0046] A cascaded dye liquor sprayer, which is non-clogging and positioned fully facing the yarn and / or fabric, is supplied by a pump / filter circulation system connected to a central collection manifold for the dye liquor. Figure 1 In the preferred configuration of the multi-stage dyeing apparatus according to the invention shown, the operation of the apparatus is essentially as if there were three conventional long-term immersions of the yarn and / or fabric, thus having two dye enhancements, thereby providing dyeing performance that is significantly superior to the dyeing performance of the apparatus according to the aforementioned patent documents.

[0047] The innovative dyeing method of the multi-stage dyeing apparatus according to the present invention comprises multiple dyeing stages for spraying yarn with a fully oriented cascaded dye liquor, alternating with simple weight extrusion to refill the interstitial bath and thus increase dye diffusion, fixation, and enhancement, including on wet products. Unlike the apparatus according to the aforementioned patent documents, it allows the dyeing process to be carried out in a single cylinder. Advantages include: greatly simplified structure and elimination of many components, such as the special, expensive pneumatic padding machine for intermediate extrusion, which is motorized and operates under nitrogen, followed by the complex and bulky chamber for dye diffusion / fixation, the heated cylinder, the second dye cylinder, and the fan / battery unit for nitrogen circulation / dehumidification (for preventing dripping onto the extruded yarn, but now no longer necessary since operation is always performed on wet products). Further advantages include the reduction in nitrogen volume, and very importantly, the simplicity, convenience, rationality, and, most importantly, significantly lower cost compared to the dyeing apparatus according to the aforementioned patent documents, due to the completely flat-ground extension of the multi-stage dyeing apparatus according to the present invention.

[0048] Furthermore, the significant reduction in dye liquor volume compared to conventional air-dyeing equipment, and the substantial reduction in dye liquor volume compared to previous nitrogen-based dyeing equipment, allows the multi-stage dyeing apparatus according to the invention to possess two useful and advantageous technical features in an extremely economical manner. The first advantageous feature is the addition of a unit to the dye liquor circulation container for cooling the dye liquor to approximately 15°C, a characteristic temperature unique to indigo dye, at which its affinity for cellulose fibers significantly increases, resulting in better coloring performance. The second advantageous feature is the addition of ultrasonic generators to the two initial and final dyeing chambers to enhance the dyeing effect.

[0049] Its unique structural features, along with the aforementioned characteristics, enable the multi-stage dyeing apparatus according to the invention to not only provide maximum possible rationality and functionality, but also exceptional operational flexibility. In fact, in addition to possible operational variations within the apparatus according to the aforementioned patent documents, this novel dyeing apparatus, in order to obtain different levels of dye penetration and fixation, which are required for different final results on the finished garments, can vary the number of spraying stages to be used, the progress of the yarn and / or fabric or the bath / fiber contact time, the number of sprayers used, the operating speed and the percentage of residual oxygen, and the dye with a cooled and / or ultrasonically activated dye bath, by means of air supplied by a fan and / or compressed air at very low pressure, immediately oxidizing the dyed yarn at the outlet of the pad dyeing machine, with or without added oxygen, to rapidly block the degree of corticality obtained in the dyeing process, thereby preventing further penetration of the dye into the fibers during the subsequent oxidation path in the air. These new possible operational changes, individually or in combination, produce a range of different and novel end results that greatly increase the range of new types of denim and textiles that can be obtained without chemical intervention in an economical and ecological manner, fully in line with present and future expectations.

[0050] The features and advantages of the multi-stage staining apparatus according to the invention will become more apparent from the following description, provided by way of non-limiting example, with reference to the accompanying schematic diagrams, in which:

[0051] Figure 1 This is a longitudinal cross-sectional schematic diagram of an apparatus according to the invention for a continuous, eco-friendly, and sustainable dyeing system for denim fabrics and warp chains of fabrics in an inert environment with indigo and other reducing dyes, wherein the apparatus preferably has three dyeing sections.

[0052] Figure 2 yes Figure 1 A schematic diagram of the longitudinal cross-section of a single cylinder in a dyeing machine, which may reduce the progress of yarn and / or fabric;

[0053] Figure 3 yes Figure 1 A longitudinal cross-sectional diagram of a single cylinder of a dyeing device. In a possible implementation, two additional bath dyeing cavities are added to the bottom wall.

[0054] Figure 4 yes Figure 1 A longitudinal cross-sectional view of a single cylinder in a dyeing apparatus, in a possible implementation, the head is lowered;

[0055] Figure 5 yes Figure 1 A schematic diagram of the longitudinal section of a single cylinder of a dyeing device. In a possible implementation, the yarn has a preferred path in the rope and fabric, such that the spraying of the dye liquor occurs on both of its surfaces.

[0056] Figure 6 yes Figure 1 A longitudinal cross-sectional diagram of a single cylinder of a dyeing device. In a possible implementation, the bottom wall is provided with four bath dyeing cavities and there is no central manifold for collecting dye liquor.

[0057] Figure 7 yes Figure 3 In the variants of the implementation method, Figure 1 A schematic diagram of the longitudinal section of a single cylinder in the dyeing equipment;

[0058] Figure 8 This is a longitudinal cross-sectional schematic diagram of a single cylinder of a dyeing apparatus according to the present invention, which, in a possible embodiment, has two sections and no dye liquor collection manifold; and

[0059] Figure 9 This is a table comparing the technical features of the dyeing equipment according to the present invention with the technical features of the single dyeing equipment for yarn warp of denim fabrics described in the aforementioned patent document.

[0060] It should be noted that, although not shown in the following description and accompanying drawings, many components, accessories, and instruments typically found in dyeing equipment, such as regulators for dye liquor levels, temperature control units, containers for preparing and restoring dye liquor and supplying auxiliary products, automatic metering systems, command and control instruments, etc., are well known to those skilled in the art. It should also be noted that the accompanying drawings illustrate hydraulic circuits, equipped with their respective pumps and valves, which will not be described in detail below, as they are also well known to those skilled in the art.

[0061] The accompanying drawings illustrate some possible embodiments of an apparatus for dyeing yarns and / or fabrics according to the present invention, all indicated by reference numeral 10. The dyeing apparatus 10 is designed to dye at least one continuous textile support 100, typically in the form of yarns and / or fabrics, such as, for example, warp chains of denim, using a dye solution B, preferably based on indigo or other reducing dyes. The dyeing apparatus 10 includes a single cylinder 12 having a parallelepiped shape, within which the textile support 100 moves. The cylinder 12 contains, in sequence:

[0062] - At least one first cavity 14, located near the bottom wall 16 and the first head 22 of the cylinder 12, is provided with at least one return roller 18 for guiding the textile support 100 into the cylinder 12 and configured to at least partially fill with a predetermined amount of dye liquor B. This predetermined amount of dye liquor B primarily functions as a watertight seal between the surrounding environment and the cylinder 12; and

[0063] - At least one first internal partition 20 is located near the first head 22 of the cylinder 12, is integral with the sidewall of the cylinder 12 and is configured to be immersed in the lower portion of the dye solution B in the first cavity 14 to facilitate watertight function.

[0064] Inside the cylinder 12, downstream of the first cavity 14 and the first internal partition 20, there is therefore a first dyeing partition chamber 24A and at least one second dyeing partition chamber 24B, 24C, in which the textile support 100 is not immersed in the dye solution B in any way. Each dyeing compartment 24A, 24B, 24C includes at least one return roller 26A, 26B, 26C for the textile support 100, arranged to guide the textile support 100 to move vertically or horizontally within its respective dyeing compartment 24A, 24B, 24C; at least one dispensing device 28A, 28B, 28C, preferably of cascaded type, arranged to dispense dye liquor B onto the textile support 100; and at least one extrusion device 30A, 30B, 30C having opposing idle rollers, positioned at the outlet of the respective dyeing compartment 24A, 24B, 24C and configured to at least partially dehydrate the textile support 100 leaving its respective dyeing compartment 24A, 24B, 24C and before entering subsequent dyeing compartments 24A, 24B, 24C or before leaving the vat 12.

[0065] exist Figures 1 to 7 In one embodiment of the dyeing apparatus 10, three different dyeing compartments 24A, 24B, and 24C are provided inside the vat 12. On the other hand, in... Figure 8 In one embodiment of the dyeing apparatus 10, two different dyeing compartments 24A and 24B are provided inside the vat 12. The number of dyeing compartments inside the vat 12 can be varied as needed in any case.

[0066] Inside cylinder 12, downstream of dyeing compartments 24A, 24B, and 24C, there are also, in sequence:

[0067] - At least one second cavity 32, located near the bottom wall 16 of the cylinder 12 and at the second head 34 of the cylinder 12 opposite the first head 22, is provided with at least one return roller 36 for disengaging the textile support 100 from the cylinder 12 and is configured to be at least partially filled with a predetermined amount of dye liquor B. Therefore, similar to the first cavity 14, the predetermined amount of dye liquor B in the second cavity 32 primarily functions as a watertight seal between the cylinder 12 and the surrounding environment; and

[0068] - At least one second internal partition 38 is located near the second head 34 of the cylinder 12, is integral with the sidewall of the cylinder 12 and is configured to be immersed in the lower portion of the dye solution B in the second cavity 32 to facilitate watertight function.

[0069] The dyeing apparatus 10 includes at least one cover 40A, 40B, 40C, which is watertightly engaged with the internal partitions 20, 38 and the sidewalls of the vat 12 to close the vat 12 at the top and watertightly isolate the dyeing compartments 24A, 24B, 24C from the surrounding environment. Figures 1 to 8 In an embodiment of the dyeing apparatus 10, each dyeing compartment 24A, 24B, 24C contained in the vat 12 is preferably provided with a single cover 40A, 40B, 40C.

[0070] Downstream of cylinder 12, and therefore outside of cylinder 12, the dyeing apparatus 10 also includes at least one extrusion and traction device 42 with opposing motorized rollers, configured to simultaneously traction the textile support 100 and remove excess liquid from the textile support 100 once it is withdrawn from cylinder 12. The dyeing apparatus 10 also includes a hydraulic system 46 with at least one container 48 designed to store, circulate, and supply dye liquor B to the interior of each dispensing device 28A, 28B, 28C and each cavity 14, 32 of cylinder 12. Container 48 is advantageously provided with heat-regulating devices 58 for heat-regulating the dye liquor B. These heat-regulating devices 58 may consist of one or more cooling units, such as, for example, coils, to cool the dye liquor B.

[0071] The cylinder 12, having a parallelepiped shape, preferably extends horizontally. More preferably, the bottom wall 16 of the cylinder 12 is shaped such that, in addition to the first cavity 14 and the second cavity 32, a central collection manifold 50 for dye solution B is formed at its peripheral location. More specifically, on the bottom wall 16 of the cylinder 12, approximately at the midpoint between the first cavity 14 and the second cavity 32, there is at least one manifold 50 for collecting dye solution B dispensed by the dispensing devices 28A, 28B, 28C of each dyeing compartment 24A, 24B, 24C. The collection manifold 50 is hydraulically connected to a hydraulic system 46 and a corresponding container 48 to facilitate the recirculation of dye solution B to the dispensing devices 28A, 28B, 28C.

[0072] like Figures 1-5 As shown in the embodiment of dyeing apparatus 10 in 7, the bottom wall 16 of cylinder 12 may preferably have a portion inclined relative to the horizontal plane and descends from each cavity 14, 32 toward the central collection manifold 50. In this way, the central collection manifold 50 can collect any overflow of dye solution B from the cascaded dispensing devices 28A, 28B, 28C and from the cavities 14, 32, and then return it to circulation via the hydraulic system 46.

[0073] exist Figure 8 In the cylinder 12, the bottom wall 16 can preferably be provided with a portion inclined relative to the horizontal plane, which conveys the dye liquor B distributed by the cascaded distribution devices 28A, 28B, 28C from the center of the cylinder 12 itself to the cavities 14, 32 hydraulically connected to the hydraulic system 46.

[0074] exist Figures 1-3 In the embodiment of dyeing apparatus 10 of 5-8, the height of the opposing heads 22, 34 of the cylinder 12 is substantially equal to the height of the corresponding internal partitions 20, 38. On the other hand, in Figure 4 In one embodiment of the dyeing apparatus 10, the opposing heads 22, 34 of the cylinder 12 are lowered relative to their respective internal partitions 20, 38. In other words, in this embodiment, the opposing heads 22, 34 of the cylinder 12, together with the bottom wall 16, have the minimum height required to close each cavity 14, 32 of the cylinder 12.

[0075] Independent of the height of the opposing heads 22, 34 of cylinder 12, each internal partition 20, 38 may have its own groove profile 52 at the top, which, through a corresponding transverse groove profile (not shown) connected to cylinder 12, forms a watertight peripheral container for the caps 40A, 40B, 40C, which are preferably removable from cylinder 12. The hydraulic seals of caps 40A, 40B, 40C may also be replaced with filler. As previously described, the internal partitions 20, 38 ensure, and bath dyeing of the textile support 100 entering and leaving cylinder 12 by immersing the bottom of the dye liquor B in their respective cavities 14, 32, these cavities 14, 32, combined with the upper network of peripheral and transverse grooves, perform the primary function of a hydraulic barrier, which is necessary to inert cylinder 12. In fact, the hydraulic system 46 may be provided with at least one circuit 54A, 54B for supplying inert gas N, preferably nitrogen, to each dyeing compartment 24A, 24B, 24C, so as to carry out the dyeing of the textile support 100 in a completely oxygen-free atmosphere or with a predetermined and controlled residual oxygen, in other words, in a substantially inert environment. Specifically, as shown in the figures, a first circuit 54A may be provided for supplying the cylinder 12, and a second circuit 54B may be provided for supplying the container 48.

[0076] Preferably, as shown in all embodiments of the dyeing apparatus 10 in the accompanying drawings, each dispensing device 28A, 28B, 28C is positioned at the tangent point between the corresponding lower return rollers 26A, 26B, 26C and the textile support 100 surrounding the input of the lower return rollers 26A, 26B, 26C. In other words, each dispensing device 28A, 28B, 28C is advantageously positioned at the so-called “NIP” of the corresponding lower return rollers 26A, 26B, 26C, i.e., at the point of maximum hydrodynamic performance, and therefore at the point of maximum exchange between the dye liquor B and the textile support 100. Again preferably, each dispensing device 28A, 28B, 28C is constituted by a non-clogging cascade spraying device having a width substantially equal to or greater than the width of the textile support 100 moving within the cylinder 12.

[0077] The extrusion and pulling device 42 with relatively motorized rollers can preferably be composed of a so-called pad-dyeing machine with pneumatic pressure. Downstream of this pad-dyeing machine, there is one or more devices 44 for blowing air, which may or may not have oxygen added thereto, so as to increase the level of oxidation of the textile support 100 once it leaves the cylinder 12.

[0078] As previously described, the dyeing apparatus 10 according to the invention is advantageously provided with additional devices configured to improve the dyeing capacity of the textile support 100. At least one of the cavities 14, 32 of the cylinder 12 is in fact provided with a corresponding ultrasonic generator 56, designed to increase the bathing effect of the dye solution B contained in these cavities 14, 32. Furthermore, the container 48 is advantageously provided with a heat-regulating device 58 for heat-regulating the dye solution B, consisting of, for example, at least a set of coils for cooling such dye solution B, in order to further increase the coloring properties of the dye solution B contained in the container 48, particularly when such dye solution B is indigo-based.

[0079] Therefore, it has been shown that the multi-stage dyeing apparatus according to the invention achieves the objectives stated above. In fact, the multi-stage dyeing apparatus according to the invention, preferably configured to operate with indigo and other reducing dyes in an inert environment and equipped with a single cylinder, is very simple, easy to operate, and easy to control and maintain. Most importantly, it has a significantly lower cost than the apparatus according to the aforementioned patent documents. It not only includes all the claimed advantages but also adds other advantages, providing greater operational flexibility and better dyeing performance. A systematic comparison between the technical features of the preferred embodiment of the multi-stage dyeing apparatus according to the invention and the corresponding technical features of the dyeing apparatus for the warp chains of denim fabrics according to the aforementioned patent documents can be found in… Figure 9 The table in the document.

[0080] On the other hand, referring to the multifunctional fabric dyeing system described in document WO 2020 / 053677 A1, it should be emphasized that the multi-stage dyeing equipment according to the invention is essentially a simple dyeing vat, preferably used for the warp chain of denim fabrics, which operates continuously and in one direction in an inert, ecological, and economical environment. Due to its particular features, the multi-stage dyeing equipment according to the invention advantageously replaces eight or more dyeing vats in a single unit or multiple units. These dyeing vats typically form part of a conventional production line for continuous dyeing with indigo and other reducing dyes, and typically consist of 3-4 pretreatment vats, 8-10 dyeing vats, and 3-4 posttreatment vats. The multi-stage dyeing equipment according to the invention is not autonomous, multifunctional, or bidirectional, but simply performs a single dyeing stage continuously.

[0081] Due to their unique structural and functional characteristics, the multi-functional dyeing system described in document WO 2020 / 053677 A1 allows for maximum operational flexibility and numerous advantages, as well as rapid delivery of dyed fabrics, but is always limited to small-length batches. On the other hand, the multi-stage dyeing equipment according to the invention modernizes, rationalizes, and ecologically sustains the dyeing of warp chains in denim fabrics on conventional continuous dyeing production lines, typically for batches of long yarns. These devices can be used both in newly constructed dyeing production lines and in modernizing existing ones.

[0082] The multifunctional fabric dyeing system shown in document WO 2020 / 053677 A1 has a rather complex structure because it includes three different cylinders, which can also be used individually and alternatively for different complementary treatments of different products, and for the use of large volumes of dye liquor. This requires appropriate hydraulic circuits, control instruments, and supply containers for each cylinder, as well as padding machines to pull the fabric at the inlet and / or dehydrate it between cylinders, and rolls / unrollers and other supplementary tools. On the other hand, the multi-stage dyeing device for warp chains of denim fabrics according to the invention has a very simple structure: there is essentially a single cylinder with a forming bottom, which always and simply operates with a single dye liquor dispensed by a cascade distributor device, and has a greatly reduced volume. This dye liquor is supplied, maintained, circulated, and controlled by a single supply container.

[0083] In the multifunctional dyeing system for fabrics described in document WO 2020 / 053677 A1, the indigo dyeing stages involve, alternatively, a long immersion and full-volume dye bath in a first tank, a long residence time in a second tank (for dye diffusion / fixation), and a second immersion in a third tank with a reduced volume of dye bath for a short immersion. On the other hand, the single-tank multi-stage dyeing apparatus for warp chains of denim fabrics according to the invention operates using a simple, novel, and innovative operating method, consisting of multiple sequential immersions with dye bath, dispersed by extrusion to refill interstitial baths. There is no immersion tank, or chamber for dye diffusion / fixation.

[0084] In the multifunctional dyeing system for fabrics described in document WO 2020 / 053677 A1, the dyeing operation, along with all other supplementary stages required by the operation cycle, is carried out by immersing the fabric in the necessary different dye liquors, which have large volumes. The single cylinder of the multi-stage dyeing apparatus according to the invention is specifically designed for a single dyeing stage of the warp yarn, but the yarn does not need to be immersed in the dye liquor. In fact, the dye liquor is uniformly supplied at all the lower "NIPs" accompanying the cylinder by means of multiple free-cascading sprayers positioned completely facing the yarn. In addition to allowing for a significant reduction in the volume of dye liquor, and with all its inherent advantages, this system also allows for a significant increase in the recycling of the dye liquor itself, the advantage of exchange with the fibers, better penetration, and uniform dye distribution.

[0085] See document WO 2020 / 053677 A1 Figure 8 Implementation C specifies that this implementation has the same technical features as the corresponding implementations shown in all other figures of this document. This implementation simply illustrates a multifunctional system for dyeing fabrics, in a specific variant of a vertical / horizontal process with combined fabrics. This process is necessary to enable dyeing on both sides of the fabric by applying dye using various systems, which does not require immersing the fabric itself in the vat, as is the case in all other implementations of the system. The purpose of this specific implementation of the system is to significantly reduce the volume of dye liquor, with undeniable advantages. In any case, this specific implementation of the system according to document WO 2020 / 053677 A1 may appear simpler than other implementations, but also has its complexity and operational complications caused by the fact that, in order to operate in the specified mode, it is necessary to use two different physical forms of dye liquor simultaneously, namely, the liquid necessary for watertightness in the small-head vat, and other forms for dyeing. For this, the completion of the system requires specific supplementary equipment, such as generators and dispensers under foamed nitrogen, systems for pressurizing nozzles with nitrogen, devices for preparing and distributing spreading paste under nitrogen, and devices for scraping. In addition to their high cost, these additional devices require special and ongoing maintenance, especially cleaning, as they can become clogged.

[0086] On the other hand, regarding the multi-stage dyeing apparatus for warp chains of denim fabrics according to the invention, the addition of the heat conditioning device 58 to the container 48 for circulating dye liquor should not be considered for the purpose specified in the system according to document WO 2020 / 053677A1, but rather utilizes the special properties of indigo dye, which has the greatest affinity for cellulosic fibers at a temperature of approximately 15°C, and thus allows for significantly better dyeing performance. This is possible and advantageous considering the substantial reduction in the volume of dye liquor used in a single tank of the multi-stage dyeing apparatus according to the invention. Again, due to the substantial reduction in the volume of dye liquor used in a single tank of the multi-stage dyeing apparatus according to the invention, it is advantageous to apply the ultrasonic generator 56 to both cavities 14, 32 to increase the bath dyeing effect.

[0087] In short, the multi-segment device for dyeing warp chains for denim fabrics according to the invention is preferably configured to operate in an inert environment using indigo and other reducing dyes, fully meeting new industrial, creative, economic and ecological needs (requiring production changes) as well as management simplicity and environmental sustainability.

[0088] Therefore, the scope of protection of this invention is defined by the appended claims.

Claims

1. A dyeing apparatus (10) for dyeing at least one continuous textile support (100) in the form of fabric and / or yarn with a dye solution (B), the dyeing apparatus (10) comprising a parallelepiped-shaped single cylinder (12) in which the textile support (100) moves, the cylinder (12) having the following sequentially arranged interior components: - At least one first cavity (14) is located near the bottom wall (16) of the cylinder (12) and at the first head (22) of the cylinder (12), and is provided with at least one return roller (18) for allowing the textile support (100) to enter the cylinder (12) and is configured to be at least partially filled with a predetermined amount of dye liquor (B), and has a watertight function between the surrounding environment and the cylinder (12); - At least one first internal partition (20) is located near the first head (22) of the cylinder (12), is integral with the sidewall of the cylinder (12) and is configured to be immersed in the lower part of the dye solution (B) of the first cavity (14) to facilitate the watertight function. - A first dyeing compartment (24A) and at least one second dyeing compartment (24B, 24C), wherein the textile support (100) is not immersed in the dye solution (B), wherein each dyeing compartment (24A, 24B, 24C) comprises: - At least one return roller (26A, 26B, 26C) is arranged to guide the textile support (100) to move vertically or horizontally within its respective dyeing compartment (24A, 24B, 24C). - At least one dispensing device (28A, 28B, 28C) is arranged to dispense the dye liquor (B) onto the textile support (100), wherein each dispensing device (28A, 28B, 28C) is positioned at a tangent point between its respective return roller (26A, 26B, 26C) and the textile support (100) surrounding the return roller (26A, 26B, 26C), the tangent point coinciding with the point of maximum hydrodynamic generation and thus with the point of maximum exchange between the dye liquor (B) and the textile support (100), and - At least one extrusion device (30A, 30B, 30C) having opposing idle rollers is placed at the outlet of the respective dyeing compartments (24A, 24B, 24C) and configured to at least partially dehydrate the textile support (100) before leaving the respective dyeing compartments (24A, 24B, 24C) and before entering subsequent dyeing compartments (24A, 24B, 24C) or before leaving the cylinder (12); - At least one second cavity (32) is located near the bottom wall (16) of the cylinder (12) and at the second head (34) of the cylinder (12) opposite the first head (22), the cavity having at least one return roller (36) for disengaging the textile support (100) from the cylinder (12) and configured to be at least partially filled with a predetermined amount of dye liquor (B), and having a watertight function between the cylinder (12) and the surrounding environment; and - At least one second internal partition (38) is located near the second head (34) of the cylinder (12), is integral with the sidewall of the cylinder (12) and is configured to be immersed in the lower part of the dye solution (B) of the second cavity (32) to facilitate the watertight function; The dyeing apparatus (10) further includes: - At least one cover (40A, 40B, 40C) is watertightly joined to the internal partition (20, 38) and the sidewall to close the cylinder (12) at the top and to watertightly isolate the staining compartment (24A, 24B, 24C) from the surrounding environment. - At least one extrusion and traction device (42) having opposing motorized rollers, which is placed downstream of the cylinder (12) and configured to simultaneously traction the textile support (100) and remove excess liquid from the textile support (100) once it leaves the cylinder (12); and - A hydraulic system (46) having at least one container (48) arranged to store, circulate, and feed the dye liquor (B) to the at least one dispensing device (28A, 28B, 28C) and inside the cavity (14, 32), The dyeing apparatus (10) is characterized by having one or more devices (44) for blowing air downstream of at least one extrusion and traction device (42) having opposing motorized rollers, the one or more devices for blowing air having or not having oxygen added thereto, the one or more devices (44) for blowing air being designed to increase the oxidation level of the textile support (100) once it leaves the cylinder (12), at least one of the cavities (14, 32) being provided with a respective ultrasonic generator (56) designed to increase the bath dyeing effect of the dye liquor (B) contained in the cavities (14, 32), and the container (48) being provided with a heat conditioning device (58) for heat conditioning of the dye liquor (B) in order to further increase the coloring properties of the dye liquor (B) contained in the container (48).

2. The dyeing apparatus (10) according to claim 1, characterized in that, The dye solution (B) is based on indigo.

3. The dyeing apparatus (10) according to claim 1, characterized in that, The heat regulation device (58) consists of one or more cooling units for cooling the dye solution (B).

4. The dyeing apparatus (10) according to any one of claims 1 to 3, characterized in that, On the bottom wall (16) of the cylinder (12), at an intermediate position between the first cavity (14) and the second cavity (32), there is at least one collection manifold (50) for collecting the dye solution (B) dispensed by the at least one dispensing device (28A, 28B, 28C), wherein the collection manifold (50) is hydraulically connected to the hydraulic system (46) and the at least one container (48).

5. The dyeing apparatus (10) according to claim 4, characterized in that, The bottom wall (16) is provided with an inclined portion relative to the horizontal plane from each cavity (14, 32) toward the collection manifold (50), such that the collection manifold (50) can collect any overflow of dye liquid (B) from the at least one dispensing device (28A, 28B, 28C) and from the cavity (14, 32) so that the dye liquid (B) can be returned to circulation through the hydraulic system (46).

6. The dyeing apparatus (10) according to any one of claims 1 to 3, characterized in that, The bottom wall (16) is provided with an inclined portion relative to the horizontal plane from the center of the cylinder (12) toward each cavity (14, 32) to collect the dye liquid (B) dispensed by the at least one dispensing device (28A, 28B, 28C) so that the dye liquid (B) can be returned to circulation through the hydraulic system (46).

7. The dyeing apparatus (10) according to any one of claims 1 to 3, characterized in that, Each internal partition (20, 38) has its own channel profile (52) at the top, and the channel profile connected to the corresponding transverse channel profile of the cylinder (12) forms a peripheral watertight housing for the cover (40A, 40B, 40C), which is removable relative to the cylinder (12).

8. The dyeing apparatus (10) according to any one of claims 1 to 3, characterized in that, The hydraulic system (46) is provided with at least one circuit (54A, 54B) for feeding inert gas into each dyeing compartment (24A, 24B, 24C) so that the dyeing of the textile support (100) is carried out in an oxygen-free atmosphere or in an inert environment with a predetermined and controlled amount of residual oxygen.

9. The dyeing apparatus (10) according to claim 8, characterized in that, The inert gas is composed of nitrogen.

10. The dyeing apparatus (10) according to claim 1, characterized in that, Each dispensing device (28A, 28B, 28C) consists of a cascaded spraying device having a width equal to or greater than the width of the textile support (100) that moves within the cylinder (12).

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