The present invention relates in general to an apparatus for dyeing of fabrics and yarns, and, in particular, an apparatus which comprises a single, multifunctional, universal use tank for rational, economical and ecological execution, when used as a component in discontinuous dyeing plants and/or in continuous dyeing lines, in dyeing processes with indigo and other reduction dyes and their many complementary treatments for weft-warp and knitwear fabrics, and for chains of warp yarn for denim fabrics.

Even more particularly, the present invention relates to a dyeing apparatus provided with a single, structurally simple, rational, advantageous and economical tank which can be used in two dyeing modes, and also for complementary treatments, in one or more types of discontinuous dyeing plants or in continuous dyeing lines, with indigo and other reduction dyes, for warp-weft and knitwear fabrics, and for chains of warp for denim fabrics, in flat, rope and loop systems. For the sake of greater descriptive clarity and ease of understanding, the present invention will be described by way of non-limiting example with reference only to its use in traditional lines for continuous dyeing with indigo, in a flat system, of chains of warp for denim fabrics.

Denim is the fabric used for the manufacture of jeans and “casual” articles of clothing in general and is quantitatively the fabric most used in the world. Classic denim fabric is obtained with the warp threads dyed and the weft thread untreated. The success of the combination of denim and blue jeans is in fact derived from dyeing of the warp of this fabric with indigo. Indigo is one of the oldest dyes, which is not easy to apply to cotton for which it has low affinity, but which has a unique characteristic which gives the fabric, and consequently the finished garment, an appearance which is shiny and pleasing in the long term. In fact, blue jeans are valued for their typical navy blue shade, which, as a result of repeated washing operations, gradually assumes a lighter shade, until a bright blue is obtained. As far as it is known, no other dye has similar properties. After many washing operations, other types of dyes tend towards a dirty grey, or stain the untreated weft yarn with an unattractive blue/greyish colour. This particular feature, together with the impression of lived-in clothing, taking the form of abrasion in the most exposed areas and creating a flexible effect on the body of people wearing it, constitutes the attraction of blue jeans, which, when produced and treated in many ways, are and will remain the most-sold item of clothing in the world.

One of the characteristics of indigo dye, which makes it unique, is the particular dyeing method required for its application to cotton yarn. This dyeing method has remained virtually unchanged from the times of the vegetable dye up to the present, over 100 years since it was synthesised. Because of its relatively small molecule and its low affinity with cellulose fibre, in order to be applied indigo dye must not only be reduced in an alkaline (leuco) solution, but also needs to be subjected to a plurality of impregnations alternating with wringing and subsequent oxidation in air. In practice, a medium or dark shade is obtained only by subjecting the yarn to a first dyeing operation (impregnation, squeezing, oxidation) followed immediately by identical over-dyeing operations which are all the more numerous, the darker the shades and the greater the stability of the colour required.

This particular dyeing method, which is typical of indigo dye, shows the enormous importance of complying with determined basic parameters relative to the times of immersion in the tank and oxidation of the yarn in the dyeing tanks. This is in order to allow the dye to be impregnated and dispensed uniformly in the cortical or surface layer of the yarn (ring dyeing) and, after perfect squeezing, to be oxidised completely before entering the next tank, so as to be able to “enhance”, i.e., intensify, the colour shade.

However, as well as being affected by these parameters, continuous dyeing with indigo is also affected by many other factors relating to the various physicalchemical contexts specific to each dyeing plant, as well as by the environmental conditions where the plant itself is installed, such as temperature and relative humidity of the air, wind bracing, altitude, etc. In addition, the different dyeing conditions (such as the number of tanks, their capacity, pick-up, type and speed of circulation of the dye bath, type and precision of the systems for automatic dosing of the indigo, the sodium hydrosulphite and the caustic soda, etc.) and the different conditions of the dye bath (such as temperature, concentration, pH, Redox potential, etc.) not only have a determining effect on the dyeing results (such as the greater or lesser intensity of shade, the stability, the corticality, etc.), but also contribute substantially to determining the final appearance of the clothing after the various treatments of washing and finishing to which it is normally subjected. It should also be specified that, contrary to other groups of dyes, for which the affinity for cotton increases as the temperature increases, in the case of indigo, the affinity and intensity of the colour, this intensity being caused by greater corticality of the dye, increase as the temperature decreases.

The most important and characterising operation of the entire denim fabric production cycle is thus that of continuous dyeing, with indigo dye, of the chains of warp yarn, before these are put on a loom for production of the fabric. Continuous dyeing with indigo of the chains of warp for denim fabrics is carried out mainly according to two systems, i.e. according to the so-called “rope” and the so-called “flat” or “wide” system. Although the above two systems differ substantially from one another, they are however united by the use of the same dyeing method, constituted substantially by three operative phases which are repeated several times, i.e., impregnation of the yarn with the reduced dye, squeezing to eliminate the excess dye bath, and oxidation of the dye by means of exposure of the dyed yarn to the air.

Typically and traditionally, dyeing with indigo of the chains of warp for denim fabrics is carried out, both in the rope system and the wide system, continuously on lines composed of machines with open tanks and at a low temperature. In detail, in the two systems, the lines for continuous dyeing with indigo are normally constituted by 3-4 pre-treatment machines, by 8-10 dyeing machines, and by 3-4 machines for the final treatments. All these machines are provided, at the exit of the yarn, with a squeezing unit in order to eliminate the excess dye bath, whereas the dyeing machines are also provided with sets of cylinders exposed to the air for the oxidation of the yarn. The tanks of the pre- and post-treatment machines have dimensions different from those of the dyeing machines, but all are of the open type, with a parallelepiped form with a bottom with double inclination: those of the dyeing machines have a dye bath capacity which varies between 1 ,000 and 1 ,500 litres in the case of the flat system, and between 3,000 and 4,000 litres in the case of the rope system, since the rope system requires longer immersion times, and therefore much higher tanks, because of the form of approximately 400 threads for each rope. These quantities of dye bath determine the total volume of the bath in circulation in the plant, which can be as much as 15,000 litres approximately in the flat dyeing plants, and 40,000 litres approximately in the rope dyeing plants. The dye bath which is contained in each tank is continually recycled in order to guarantee the homogeneity of concentration in each tank. This circulation is normally carried out by means of various known piping systems, with high-capacity and low-lift centrifugal pumps, in order to avoid detrimental turbulence. The movement of the dye bath gives rise to continual replacement of the surface part of the bath itself, which is in contact with the air, the tanks being open at the top, and thus giving rise to the oxidation. The oxidation of the dye bath has the consequence of continual impoverishment of the reducing agents contained therein, i.e., sodium hydrosulphite and caustic soda, all the more so the higher the temperature of the dye bath is.

It is therefore the multiple phases of oxidation which contribute, in a manner far greater than described above, towards impoverishing the elements themselves (sodium hydrosulphite and caustic soda) of the dye bath with which the yarn is impregnated. These oxidation phases are an integral part of the dyeing cycle, and in practice they consist of exposure to the air, between one machine and another of the 8-10 dyeing machines which constitute the dyeing line, of approximately 30-40 meters of yarn impregnated with leuco. Overall, the yarn is therefore exposed to the air for several hundreds of metres in the entire dyeing line.

On this basis, it is necessary to top up the dye bath continually with the quantities of sodium hydrosulphite and caustic soda destroyed by the abovedescribed oxidations, so that this dye bath is constantly maintained in the optimum chemical conditions for the best dyeing performance, and in order to guarantee constant and reproducible results. It will be appreciated that the dye bath must also have dye continually added to it, in conditions of concentrated leuco, in the quantity necessary to obtain the colour shade desired. For continuous automatic dosing of the indigo dye, the sodium hydrosulphite and the caustic soda, various systems can be used, such as dosing pumps, weighing, volumetric and mass systems, etc., all of which are known since they are also normally used in other textile processing. It will be appreciated that the greater the volume of the dye bath, the more time is needed to take a new dye bath to the chemical/dyeing equilibrium necessary in order to obtain the same colour shade constantly. The response time to any corrective interventions will be equally long, and this does not assist obtaining of the required quality.

Another particular feature of indigo dye is due to the fact that the dye baths containing this dye are never replaced except to change colour shade. As previously stated, on the contrary, dye baths containing indigo are continually reused, subject to the titration and addition of sodium hydrosulphite, caustic soda and dye, in order to keep their chemical/dye equilibrium constant. Thus, each dyeing line has a certain number of containers, equal to the number of variants of blue being produced, for the overall capacity of all of the dyeing tanks. These containers are used for the storage and refilling of the dye baths.

For quality purposes, it is of the greatest importance to succeed in keeping the physical-chemical conditions of the dye bath constant for the entire time necessary to dye the whole batch of yarn. On average, the time varies between 10 hours and 30 hours, depending on the length of the yarn chain and the dyeing speed. However, despite continual mechanical and hydraulic improvements of the dyeing lines and help from sophisticated control and dosing systems, as a result of the large volumes involved, and the many causes described above, which, individually or in association with one another combine to create undesirable variations of the dye bath conditions, continuous dyeing with indigo continues to be a complex operation.

In addition, to complicate the production of the denim fabric further, there are various economical and ecological problems, aggravated also by the fact that the production of this fabric has become greatly diversifed, and is carried out in batches with ever shorter lengths. This situation is the result of the fact that, compared with what happened in the past, denim fabric is being used increasingly in the field of fashion, where it is not only necessary to have considerable operative flexibility and timely productivity, but where there are also continual requirements for new, original and exclusive articles of clothing, all to promote sales, in order to beat the competition and acquire new markets.

In fact, over a period of time, denim fabric has undergone considerable and continual development, going from initial production with the warp dyed only with indigo in few shades of colour, to the present production, which requires a very vast range, including the addition of various complementary operations, such as prefulling, pre-dyeing, overdyeing, fixing, etc., which have required addition of the respective devices to the dyeing lines. Significant changes have also taken place in the yarns used, going from cotton alone, to various mixtures of fibres, from open- end yarns to ring-spun yarns, from large yarn counts to fine yarn counts, and including elasticised yarns and an ever greater number of threads in order to obtain increasingly light denims.

However, it is in the finishing operations that, in order to follow fashion, there has been a technological revolution which has seen denim fabric evolve compared with being normally used as it was produced on a loom. In fact, operations have been added of washing, mercerisation, over-dyeing by means of immersion, foaming or spreading, with these last two systems also being used for application of special products in order to vary the appearance of the fabric, above all in order to obtain particular effects after the garments manufactured have been washed.

The influence of fashion has been felt to an even greater extent in the sector of jeans, where a new production activity has even emerged, consisting of laundries for jeans. At one time, as previously described, the progressive fading of jeans, an effect which provides a particular bright blue shade and a pleasing impression of a lived-in garment, was the natural result of personal use and consequent multiple washing operations. These effects, like many others, are now already present in the new garments manufactured, and are in fact added by the laundries for jeans, which, by means of multiple treatments, put the final users in a position of being able to enjoy these effects immediately. In the laundries, the jeans are washed, faded with various chemical products, enzymes, ozone and/or lasers, treated with pumice stone, and polished with emery, etc. These treatments provide the jeans with a “vintage” appearance, which is taken as far as creating tears and rips in the fabric.

All of these final treatments, both the ones which are carried out directly on the denim fabric, and those which are carried out on the manufactured garments, necessarily require the characteristics of the basic dyes, or that of the warp, to be suitable, and to assist in obtaining and emphasising the desired effects. However, in the entire clothing sector, jeans also have the unfortunate record of being the garment which has the worst environmental and social impact. The production cycle of blue jeans, from growing of the cotton until they reach the point of sale, in fact requires very high levels of water and energy consumption, as well as the use of chemical substances in various production phases. It is thus apparent that the most polluting and characterising operation of the entire cycle of production of denim fabric is that of continuous dyeing, with indigo dye and/or other reduction dyes, of the chains of warp yarn before these are put onto a loom for production of the fabric. In the light of all the above problems, the two objectives which all denim producers proposed to achieve, i.e. eco-sustainability in production and the maximum operative flexibility, are not only reasonable and logical, but also indispensable. For known reasons, eco-sustainability in production is not only necessary, but now essential, whereas the maximum operative flexibility is required in order to keep up with the ever more frequently changing and unforeseeable demands of fashion. As far as ecology is concerned, it is probable, indeed it is now required and considered likely to take place soon by many consumer protection organisations, that there will be an international law which imposes drastic reduction of consumption, as well as compliance with precise standards aimed at the protection of health and the environment.

As far as dyeing of warps is concerned, these two objectives can only be achieved by means of use of a new conceptually developed apparatus which makes possible, as well as the operative processes rooted in tradition, also new ecological processes which can be carried out only in an inert environment, preferably under nitrogen, which, as well as the drastic reduction in the volume of dye bath, energy consumption, water and chemical products, also make possible the feasibility of previously unknown dyeing results. This technological solution would allow denim manufacturers, without organisational upheavals and very simply and rationally, always to use the same dyeing line both with the traditional dyeing system in air, thus maintaining their customary production, and with the previously unknown ecological system in an inert environment (preferably under nitrogen) and with a reduced volume of dye bath, which, in addition to the savings proclaimed, permits extension of the production range with the addition of new articles, which are original and exclusive since they are not repeatable on the traditional dyeing plants.

In practice, this would involve a dyeing line which still has the usual 8-10 dyeing machines and corresponding accessories, usable without any particular tricks both in air and in an inert environment, according to the particular but traditional method of application of indigo, or by means of a plurality of impregnations (8-10), interspersed by wringing and subsequent oxidations in air, this being the only method which makes it possible to obtain very dark shades, and with a high level of stability, using dye baths with a low concentration.

It is specified that the ecological dyeing system differs from the traditional one in that it is not carried out in air, but in an inert environment, preferably under nitrogen, a condition which advantageously permits the reduction of the volume of dye bath by approximately two thirds compared with that in air, with a drastic reduction of the consumption of chemical products and with other advantages. This is possible because, in the system for dyeing in an inert environment, the yarn is not totally immersed in the dye bath, i.e., in fact, in an inert environment, the dye bath which impregnates the part of the yarn which is not immersed does not become oxidised, but remains in the “leuco” state, continuing to be diffused and fixed on the fibre. In addition, in an inert environment, preferably under nitrogen, the chemical reduction of the indigo is total and perfect, and the leuco is broken down into particles with nanometric dimensions which increase the dyeing capacity thereof. This increased dyeing capacity of the leuco permits improved penetration and better fixing on the fibre compared with the traditional dyeing system in air, with advantageous dyeing results in terms of stability, intensity and brightness, which differences enhance the final fabric from a qualitative point of view.

It is specified that the ecological system for dyeing in an inert environment has already been disclosed in documents EP 1771617, EP 1971713, EP 3464702 and WO 2020/053677 filed in the name of the same applicant. However, these documents do not relate to the normal dyeing machines, but to special and structurally complex dyeing plants designed to reduce the number of, and/or replace, the normal 8-10 dyeing machines in the traditional dyeing lines. Consequently, in order to obtain the aforementioned objective, these dyeing plants must operate, with significant problems, using high-concentration dye baths. Their structural complexity, the high cost, the various problems relating to the aspects described above, the rigid and limited operative flexibility, and the impossibility of use also in air, unless there are large numbers of apparatuses and there is therefore prohibitive investment, have limited the diffusion of these apparatuses to only ten or so examples.

The fact must also be added that the denim producers, the dyeing lines of which all operate for 24 hours a day, under no circumstances want to install plants for dyeing a particular single product, which, for many reasons, cannot always be used full-time. There is therefore a need to devise new dyeing technology under the profile of new, creative, economical and ecological industrial demands which require maximum operative flexibility, versatility, timeliness in changes of production, as well as economical management and environmental sustainability.

The scope of the present invention is thus to provide an apparatus with dual modes of use for dyeing of fabrics and yarns, which apparatus can resolve the above-described disadvantages of the prior art in a manner which is extremely simple, economical and particularly functional.

In detail, a scope of the present invention is to provide a dyeing apparatus with a single tank which, without changing the drawing-in of the fabric and/or yarn, can operate with dual modes of use, i.e. traditional in air, and ecological in an inert environment, for dyeing with indigo with the traditional multi-phase method with low- concentration dye baths, which tank can also be used as a component of the dyeing plants which operate discontinuously and/or in the continuous lines in the flat, rope and loop systems.

Another scope of the present invention is to provide a dyeing apparatus with a single tank which, in one or more examples, can be used in processes for continuous dyeing with indigo, with the traditional multi-phase method with low- concentration dye baths, such that these dyeing processes can be carried out with a full volume of bath according to the traditional method, or in contact with air, and also, as an alternative, with a reduced volume of bath in an inert environment.

Another scope of the present invention is to provide a dyeing apparatus with a single tank which can operate in an inert environment, thus making it possible to reduce substantially the volume of the bath for dyeing with indigo, and consequently the consumption of sodium hydrosulphite and caustic soda.

Another scope of the present invention is to provide a dyeing apparatus with a single tank which, in one or more examples, as well as being used for dyeing with indigo, in air and/or and in an inert environment, can also be used for all the pre- and post-treatments necessary, to be carried out only in air, such as to maintain the same spare parts, the same practices, and the same ease of operation and maintenance.

Another scope of the present invention is to provide a dyeing apparatus with a single tank which, with indigo and other reduction dyes, as well as being used in discontinuous dyeing plants or in continuous lines of the chains of warp for denim, can also be used in those for weft-warp and knitwear fabrics. Another scope of the present invention is to provide a dyeing apparatus with a single tank which, both for dyeing with indigo and reduction dyes for the fabrics and chains of warp for denim fabrics, and to carry out pre- and post-treatments, can use under economically advantageous conditions both a system to cool the dye bath, and an ultrasound generator in order to improve further the colour performance and the washing effect.

Another scope of the present invention is to provide a dyeing apparatus with a single tank which can operate such as to be able to increase the present possible operative variables.

Another scope of the present invention is to provide a dyeing apparatus with a single tank which, for dyeing with indigo and other reduction dyes, makes it possible to increase the degree of fixing of the dye on the fibre, with reduction of the consumption of washing water, so as to contribute to the environmental sustainability.

Yet another scope of the present invention is to provide a dyeing apparatus with a single tank which permits dyeing with indigo in the technologically best conditions, and which makes it possible to increase the diffusion and fixing of the dye on the fibre.

These scopes and others according to the present invention are achieved by providing an apparatus with dual modes of use for dyeing of fabrics and yarns as described in claim 1 .

Further features of the invention are indicated by the dependent claims, which are an integral part of the present description.

The dyeing apparatus according to the present invention, with dual modes of use for discontinuous and/or continuous dyeing, in fact makes it possible to operate not only with the traditional technology for dyeing with indigo, which is multi-phase, uses low-concentration dye baths, and is carried out in contact with the air, but also simply and rationally with the new technology for ecological dyeing in an inert environment, with all the corresponding merits and advantages. According to the needs, this dyeing apparatus with dual modes of use, without changing the drawingin of the fabric and/or the yarn, can operate alternatively with the technology in air, or in a previously unknown mode with that in an inert environment, which is an economical and ecologically method, thus combining the different flexibilities of the two operative systems, and making it possible to provide a new range of different, particular, and previously unknown articles of clothing.

With reference to the possibility of the dyeing apparatus according to the present invention being able to operate both with a full volume of dye bath and with a reduced volume, it is specified that these operative modes are also indicated in document IT 1276824 filed in the name of the same applicant, however in a completely different manner, and for a different use. The dyeing apparatus according to the present invention differs totally from that of the above document not only structurally, but above all functionally. In fact, the scope of the dyeing apparatus illustrated in document IT 1276824, which can operate only in air, was to dye with indigo with a full volume of dye bath, which is a compulsory condition as clearly specified in the document itself, so as to keep the yarn completely under the dye bath, and on the other hand to dye with a reduced dye bath with other classes of dyes. The above condition is indispensable since, with a reduced level of dye bath and operating in air, the bath for dyeing with indigo which impregnates the part of the fabric and/or yarn which is not immersed would be detrimentally oxidised, thus making these textile supports unusable in practice.

In its simplicity, the dyeing apparatus according to the present invention is original, unique and ingenious, since, by modifying and adding to the tank of the traditional dyeing machines, the present component for all lines for dyeing continuously with indigo, in air, of chains of warp for denim, can be used in a particular and previously unknown way, both for traditional dyeing in air, and for dyeing in an inert environment (preferably under nitrogen), i.e. with the ecological dyeing system of the future. This dual operativity adds to the almost century-old tradition of multi-phase dyeing, with indigo, in air and with low-concentration dye baths, also the original and previously unknown operativity in an inert environment (preferably under nitrogen), in an ecological manner, and with previously unknown, exclusive and inimitable dyeing results.

In practice, in order to be able to achieve this, the tank of the traditional machines for dyeing in air has been modified and completed with various technical features, including rounding of the bottom, the addition of a second feed and return system for the dye bath, in order to be able to operate also at a low level, and the addition of two partition walls at the entry and exit of the yarn, for the function of conveying the circulation of the dye bath full face, and creating two watertight interspaces. The partition walls are provided with an upper channel which, connected to the two side channels applied to the tank, create the watertight seat for a movable and/or removable upper lid. Other technical features then concern the possibility of feeding, regulation, control and discharge of the inerting agent, which is preferably nitrogen. Substantially, in order to go from the traditional system of dyeing in air to the special one in an inert environment, the manoeuvres are reduced simply to opening and/or closing some valves. It is specified that the rounding of the bottom, the addition of the inner partition walls and of the upper lid are to be considered also improvements of the traditional system for dyeing in air, since the rounded bottom prevents stagnation of dirt and facilitates the cleaning, the partition walls create the diffusion and circulation the full front of the dye bath, whereas the lid not only eliminates odours and fumes, thus improving the environmental conditions, but also contributes towards preventing surface oxidation of the dye bath, with reduction of the consumption of caustic soda and sodium hydrosulphite.

It is also interesting to see that the cost of the aforementioned modifications and additions to the tank is truly insignificant, if compared with the cost of a traditional dyeing machine, and if account is taken of the enormous advantages acquired with the duality of use, i.e. both in air and in an inert environment, ecologically, with a drastic reduction of the volume of dye bath, with significant savings and new operative flexibility derived from the previously unknown and exclusive results. As far as this new ecological technology is concerned, it is specified that, during the dyeing phase, which is the only phase of the entire process carried out in an inert environment, there is no consumption of the inerting agent except for the initial inerting. It is also specified that, in all the traditional lines for continuous dyeing with indigo of the chains of warp, in the various flat and rope systems, the tanks of the 8-10 dyeing machines have a different shape and capacity from the tanks of the 3-4 pre-treatment machines and the 3-4 post-treatment machines which contribute towards the composition of the dyeing lines themselves.

The possibility for the dyeing apparatus according to the present invention to operate equally well with full volume and with a reduced volume makes it extremely versatile, in the sense that this dyeing apparatus can carry out not only the traditional washing operations in two modes, but also has applications for particular products with a low volume of dye bath, which is a condition of maximum efficiency, as well as being economical. This means that the entire composition of the dyeing line can be obtained with all the operative machines produced according to the present invention, i.e. with a single model of tank, although the tank which can be used for the complementary treatments is missing some components compared with the dyeing tank. The missing components comprise the devices for operating in an inert environment and the upper lid, with the addition however of the controlled feed of the washing water and the possible application of ultrasound generators in order to intensify the efficiency of washing, with consequent substantial saving of water. This new dyeing apparatus thus makes it possible to produce a dyeing line which, as previously mentioned, all the denim producers are waiting for, in other words a new dyeing line which, in the least costly way possible, combines with the traditional elements technological and ecological innovations, with new performance levels, which project it into the future.

The features and advantages of an apparatus with dual modes of use for dyeing of fabrics and yarns according to the present invention will become more apparent from the following description, provided by way of non-limiting example, with reference to the appended schematic drawings, in which: figure 1 is a schematic view in lateral elevation of a preferred embodiment of the dyeing apparatus with dual modes of use according to the present invention; figure 2 is a schematic view in lateral elevation of the dyeing apparatus of figure 1 in the mode of use for dyeing with indigo with a full volume, in air; figure 3 is a schematic view in lateral elevation of the dyeing apparatus of figure 1 in the mode of use for dyeing with indigo with a reduced volume, in an inert environment; figure 4 is a schematic view in lateral elevation of the dyeing apparatus of figure 1 used for complementary pre- and post-treatment operations of the cycle for dyeing with indigo, in particular of washing, wherein the tank has a full volume; figure 5 is a schematic view in lateral elevation of the dyeing apparatus of figure 1 used for complementary pre- and post-treatment operations of the cycle for dyeing with indigo, in particular of washing, wherein the tank has a reduced volume; figure 6 is a schematic view in lateral elevation of the dyeing apparatus of figure 1 used for possible treatments with particular products, wherein the tank has a reduced volume; figure 7 is a schematic view in lateral elevation of a dyeing section of a line for continuous dyeing with indigo of the chains of warp for denim fabrics, in flat and/or in rope systems, wherein this dyeing section comprises a plurality of dyeing apparatuses according to the present invention, and wherein these dyeing apparatuses are illustrated in the dual mode of supply and return of the dye bath; figure 8 is a schematic view in lateral elevation of an entire line for continuous dyeing with indigo of the chains of warp for denim fabrics, wherein the pre-treatment, dyeing and post-treatment sections are illustrated; and figure 9 is a schematic view in lateral elevation of the dyeing apparatus of figure 1 for the uses according to figures 1 to 6, but in a particular version in order to operate with the fabric and/or the chains of warp moved discontinuously, in alternating directions.

It is specified that, in the following description and in the appended figures, there is no illustration, since they are well known to persons skilled in the art, of numerous components, accessories and instruments with which all dyeing machines are normally equipped, such as, for example, regulators for the level of the bath, thermoregulation units, preparation containers, containers for recovery of the dye bath and for supply of auxiliary products, automatic dosing systems, command and control instruments, etc. It is also specified that the appended figures illustrate hydraulic circuits without respective pumps, etc., which will not be described in detail hereinafter, since they are also well known to persons skilled in the art.

The figures show a preferred embodiment of the apparatus with dual modes of use for dyeing of fabrics and yarns according to the present invention. The dyeing apparatus is indicated as a whole by the reference number 10. The dyeing apparatus 10 is designed for the dyeing of a continuous and moving textile support 100, which can preferably, but not exclusively, be constituted by a weft-warp and knitwear fabric, or by a chain of warp yarn for denim fabrics. The means for the movement of the textile support 100 entering into and exiting from the dyeing apparatus 10 can be of the type known in the prior art, and will therefore not be illustrated in detail.

The dyeing apparatus 10 comprises a single tank 12. In turn, the tank 12 comprises at least one side wall 14, which is substantially vertical and surrounds the tank 12 completely. The tank 12 can thus have any form in plan view, such as, for example, circular, with a single side wall 14 with a cylindrical form, or quadrangular, with four side walls 14 which are orthogonal to one another.

The tank 12 also comprises at least one bottom wall 16, which has a convex outer surface. In other words, the profile of the bottom wall 16, which can have any form, is advantageously rounded or “cambered” in such a way as to avoid stagnation of dirt inside the tank 12, and to facilitate the cleaning thereof.

The tank 12 also comprises at least one first inner partition wall 18, which faces a first inner surface 14A of the side wall 14 placed at an edge 22 of entry of the textile support 100 into the tank 12, and at least one second inner partition wall 20, which faces a second inner surface 14B of the side wall 14 placed at an edge 24 for exit of the textile support 100 from the tank 12. At least one dyeing compartment 26 of the tank 12 is provided between the first inner partition wall 18 and the second inner partition wall 20. On the other hand a first interspace 28 for the passage of the textile support 100 from the entry edge 22 of the tank 12 to the dyeing compartment 26 is provided between the first inner partition wall 18 and the first inner surface 14A of the side wall 14. Finally, a second interspace 30 for the passage of the textile support 100 from the dyeing compartment 26 to the exit edge 24 of the tank 12 is provided between the second inner partition wall 20 and the second inner surface 14B of the side wall 14.

At least one upper lid 32 engages in a mobile and/or removable manner on the first inner partition wall 18, on the second inner partition wall 20 and on the upper side channels of the tank 12, forming a perimeter system for watertight sealing of the dyeing compartment 26. The upper lid 32 can thus be opened and/or removed in order to carry out traditional dyeing in air of the textile support 100 inside the dyeing compartment 26.

A first hydraulic circuit 34, 36 and 38, 40, which is designed to feed a first process fluid B into the tank 12, to circulate the first process fluid B inside the tank 12 and to discharge the first process fluid B from the tank 12, so that the first process fluid B can flow both in the dyeing compartment 26 and in the first interspace 28 and second interspace 30, is connected operatively to the tank 12. Preferably, the first process fluid B consists of a dye bath based on indigo and/or other reduction dyes for the textile support 100.

A second fluid circuit 42, which is designed to feed a second process fluid N into the dyeing compartment 26, to circulate the second process fluid N inside the dyeing compartment 26 and to discharge the second process fluid N from the dyeing compartment 26, so that the second process fluid N can only flow into the dyeing compartment 26 due to the watertight seal performed by the first process fluid B contained in the first interspace 28 and second interspace 30, is also connected operatively to the tank 12. Preferably, the second process fluid N consists of an inert gas which is designed to generate an inert environment inside the dyeing compartment 26. Even more preferably, this inert gas is nitrogen.

The first hydraulic circuit 34, 36 and 38, 40 for feeding the first process fluid B into the tank 12, for circulation of the first process fluid B inside the tank 12 and to discharge the first process fluid B from the tank 12, comprises first means 34, 36 for entry/exit of the first process fluid B, which are operatively connected to the tank 12 and are positioned at a first distance D1 from the lower end of the bottom wall 16. The first means 34, 36 for entry/exit of the first process fluid B are thus designed to feed this first process fluid B up to a first predefined filling level L1 both in the dyeing compartment 26 and in the first interspace 28 and second interspace 30. This operative configuration of the tank 12 is shown in figure 3, where it can be seen that, above the first predefined filling level L1 of the first process fluid B, the second process fluid N is present.

The first hydraulic circuit 34, 36 and 38, 40 for feeding the first process fluid B into the tank 12, for circulation of the first process fluid B inside the tank 12 and to discharge the first process fluid B from the tank 12 also comprises second means 38, 40 for entry/exit of the first process fluid B, which are also operatively connected to the tank 12 but are positioned at a second distance D2 from the lower end of the bottom wall 16. The second means 38, 40 for entry/exit of the first process fluid B are thus designed to feed this first process fluid B up to a second predefined filling level L2 both into the dyeing compartment 26, and into the first interspace 28 and the second interspace 30.

As shown in figure 1 , the second distance D2 is greater than the first distance D1. Consequently, the second predefined filling level L2 is greater than the first predefined filling level L1. This operative configuration of the tank 12 is shown in figure 2, where it can be seen that above the second predefined filling level L2 of the first process fluid B, only air is present.

Preferably, the tank 12 is provided with means 44 for thermoregulating the first process fluid B. Even more preferably, these thermoregulating means 44 can consist of one or more coils for the circulation of a thermoregulating fluid. The coils are advantageously positioned on respective outer surfaces of the bottom wall 16 of the tank 12.

Again preferably, the tank 12 is internally provided with a plurality of return rollers 46 for the textile support 100. The return rollers 46 are designed to transfer the textile support 100 from the first interspace 28 to the dyeing compartment 26, in order to increase the drawing-in of the textile support 100 inside the dyeing compartment 26 and to transfer the textile support 100 from the dyeing compartment 26 to the second interspace 30.

In the embodiment of the dyeing apparatus 10 in figure 1 , this dyeing apparatus 10 comprises a first device 48 for squeezing the textile support 100. This first squeezing device 48, which is preferably of the type with opposite cylinders and is defined in technical terms as a “foulard”, is positioned at the edge 24 for the exit of the textile support 100 from the second interspace 30 of the tank 12 and is configured to extract excess liquids from the textile support 100.

In the embodiment of the dyeing apparatus 10 in figure 9, this dyeing apparatus 10 comprises on the other hand, in addition to the first aforementioned squeezing device, also a second device 50 for squeezing the textile support 100. This second squeezing device 50, which is preferably identical to the first squeezing device 48, is positioned at the edge 22 for entry of the textile support 100 into the first interspace 28 of the tank 12, and is again configured to extract excess liquids from the textile support 100. The presence on the dyeing apparatus 10 of both the squeezing devices 48 and 50 permits dyeing of the textile support 100 in the operative condition in which this textile support 100 is being moved discontinuously, in alternating directions (forwards-backwards).

As well as for dyeing of the textile support 100, the dyeing apparatus 10 according to the present invention can advantageously be used to carry out other treatment operations on the textile support 100, and/or operations of washing in the tank 12. As shown in figures 4 to 6, the dyeing apparatus 10 can thus comprise a third hydraulic circuit 54 for feeding at least one third process fluid W, T into the tank 12, for the circulation of this third process fluid W, T inside the tank 12 and for the discharge of this third process fluid W, T from the tank 12. The third hydraulic circuit 54 is hydraulically connected to the first hydraulic circuit 34, 36 and 38, 40, so as to feed the third process fluid W, T up to the first predefined filling level L1 or up to the second predefined filling level L2 both in the dyeing compartment 26, and in the first interspace 28 and in the second interspace 30. In this condition of use of the dyeing apparatus 10, the respective tank 12 can be internally provided with at least one ultrasound generator 56, which is designed to increase the efficiency of the first process fluid B and/or the third process fluid W, T when circulated inside the tank 12.

Preferably, the dyeing compartment 26 is internally provided with at least one volume reducer device 52. Each volume reducer device 52, which consists substantially of a chamber which acts as a volume reducer chamber, has in fact the function of reducing the volume of the first process fluid B and/or the third process fluid W, T contained in the dyeing compartment 26.

On the basis of the use of the dyeing apparatus 10 shown in figures 4 and 5, i.e. with the tank 12 used for washing operations, the third process fluid W, T consists of a washing fluid W. In figure 4, the tank 12 operates with a full volume of washing fluid W, whereas in figure 5 the tank 12 operates with a reduced volume of washing fluid W.

On the basis of the use of the dyeing apparatus shown in figure 6, i.e. with the tank 12 used for possible treatments of the textile support 100 with particular products, the third process fluid W, T consists of any fluid T designed for implementation on the textile support 100 of treatments complementary to the dyeing, such as, for example, pre-fulling, pre-dyeing, overdyeing, fixing, and others.

It is thus shown that the apparatus with dual modes of use for dyeing of fabrics and yarns according to the present invention achieves the scopes previously set out.

The apparatus with dual modes of use for dyeing of fabrics and yarns thus designed can in any case undergo numerous modifications and variants, all of which come within the same inventive concept; in addition, all the details can be replaced by technically equivalent elements. In practice, any materials, as well as forms and dimensions can be used, according to the technical requirements.

The scope of protection of the invention is thus defined by the appended claims.