MULTI-SECTION APPARATUS FOR DYEING, IN AN INERT ENVIRONMENT, OF FABRICS AND YARNS, WITH INDIGO AND OTHER REDUCTION DYES

Abstract

A description is provided of an apparatus for dyeing a textile support comprising a single tank which is provided in its interior, in sequence, with: one first shaped cavity having a watertight function between the surrounding environment and the tank; one first internal partition wall, which is immersed in the lower part in the dye bath of the first shaped cavity for helping the watertight function; one first dyeing compartment and at least one second dyeing compartment which each comprise at least one return roller for the textile support, at least one dispensing device to dispense the dye bath on the textile support, and at least one squeezing device; a second shaped cavity containing the dye bath having a watertight function between the tank and the surrounding environment; and a second internal partition wall, which is immersed in the lower part in the dye bath of the second shaped cavity for helping the watertight

Claims

1. An apparatus (10) for dyeing, with a dye bath (B), at least one continuous textile support (100) in the form of fabrics and/or yarns, the dyeing apparatus (10) comprising a parallelepiped-shaped single tank (12) within which said textile support (100) is moved, said tank (12) being internally provided, in sequence, with: at least one first shaped cavity (14), which is obtained near the bottom wall (16) of said tank (12) and at a first head (22) of said tank (12), which is internally provided with at least one return roller (18) for said textile support (100) entering said tank (12) and is configured to be at least partially filled with a predefined quantity of dye bath (B) having a watertight function between the surrounding environment and said tank (12); at least one first internal partition wall (20), which is positioned near said first head (22) of said tank (12), which is integral with the side walls of said tank (12) and is configured to be immersed in the lower part in the dye bath (B) of said first shaped cavity (14) for helping the watertight function; one first dyeing compartment (24A) and at least one second dyeing compartment (24B, 24C) within which said textile support (100) is not immersed in said dye bath (B), wherein each dyeing compartment (24A, 24B, 24C) comprises: at least one return roller (26A, 26B, 26C), arranged to guide the movement of said textile support (100) vertically or horizontally within the respective dyeing compartment (24A, 24B, 24C), at least one dispensing device (28A, 28B, 28C), arranged to dispense the dye bath (B) on said textile support (100), and at least one squeezing device (30A, 30B, 30C) with opposite idle rollers, placed at the exit of the respective dyeing compartment (24A, 24B, 24C) and configured to dehydrate at least partially said textile support (100) leaving the respective dyeing compartment (24A, 24B, 24C) and before entering the subsequent dyeing compartment (24A, 24B, 24C) or before leaving said tank (12); at least one second shaped cavity (32), which is obtained near the bottom wall (16) of said tank (12) and at a second head (34) of said tank (12) opposite to said first head (22), which is internally provided with at least one return roller (36) for said textile support (100) leaving said tank (12) and which is configured to be at least partially filled with a predefined quantity of dye bath (B) having a watertight function between said tank (12) and the surrounding environment; and at least one second internal partition wall (38), which is positioned near said second head (34) of said tank (12), which is integral with the side walls of said tank (12) and is configured to be immersed in the lower part in the dye bath (B) of said second shaped cavity (32) for helping the watertight function; the dyeing apparatus (10) further comprising: at least one lid (40A, 40B, 40C), which engages in a watertight manner with said internal partition walls (20, 38) and said side walls to close said tank (12) at the top and insulate said dyeing compartments (24A, 24B, 24C) from the surrounding environment in a watertight manner; at least one squeezing and pulling device (42) with opposite motorized rollers, which is placed downstream of said tank (12) and is configured to simultaneously pull said textile support (100) and extract excess liquids from said textile support (100) once it has left said tank (12); and one hydraulic system (46), provided with at least one container (48), which is arranged to store, circulate and feed the dye bath (B) to said at least one dispensing device (28A, 28B, 28C) and inside said shaped cavities (14, 32), the dyeing apparatus (10) being characterised in that one or more devices (44) for blowing air, which does or does not have oxygen added to it, are provided downstream from said at least one squeezing and pulling device (42) with opposite motorised rollers, said one or more devices (44) for blowing air being designed to increase the level of oxidation of said textile support (100) once it has exited from said tank (12), in that at least one of said shaped cavities (14, 32) is provided with a respective ultrasound generator (56) which is designed to increase the bathing effect of said dye bath (B) contained in said shaped cavities (14, 32), and in that said container (48) is provided with means (58) for thermal regulation of said dye bath (B), such as to increase further the colour performance of said dye bath (B) contained in said container (48).

2. The dyeing apparatus (10) according to claim 1, characterised in that said thermal regulation means (58) are constituted by one or more heating/cooling units with refrigeration of said dye bath (B).

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

4. The dyeing apparatus (10) according to claim 3, characterized in that said bottom wall (16) is provided with inclined portions, with respect to a horizontal plane, coming down from each shaped cavity (14, 32) towards said collection manifold (50), so that said collection manifold (50) can collect the dye bath (B) coming from said at least one dispensing device (28A, 28B, 28C) and from any overflowing of said shaped cavities (14, 32) such as to put said dye bath (B) back into circulation through said hydraulic system (46).

5. The dyeing apparatus (10) according to claim 1, characterized in that said bottom wall (16) is provided with inclined portions, with respect to a horizontal plane, coming down from the centre of said tank (12) towards each shaped cavity (14, 32), so as to collect the dye bath (B) dispensed by said at least one dispensing device (28A, 28B, 28C) such as to put said dye bath (B) back into circulation through said hydraulic system (46).

6. The dyeing apparatus (10) according to claim 1, characterized in that each internal partition wall (20, 38) is provided at the top with a respective channeled profile (52) which, connecting to corresponding transverse channeled profiles of said tank (12), form a peripheral, watertight housing for said lids (40A, 40B, 40C), which are removable with respect to said tank (12).

7. The dyeing apparatus (10) according to claim 1, characterized in that said hydraulic system (46) is provided with at least one circuit (54A, 54B) for feeding an inert gas (N), within each dyeing compartment (24A, 24B, 24C), so that the dyeing of the textile support (100) is carried out in a substantially oxygen-free atmosphere, or with a predetermined and controlled residue of oxygen, in a substantially inert environment.

8. The dyeing apparatus (10) according to claim 1, characterized in that each dispensing device (28A, 28B, 28C) is positioned at the point of tangency between a respective return roller (26A, 26B, 26C) and said textile support (100) entering around said return roller (26A, 26B, 26C), said point of tangency coinciding with the point of maximum hydrodynamic yield and therefore of greatest interchange between said dye bath (B) and said textile support (100).

9. The dyeing apparatus (10) according to claim 8, characterized in that each dispensing device (28A, 28B, 28C) consists of a cascade spraying device having a width which is substantially equal to or greater than the width of said textile support (100) moved within said tank (12).

Description

[0052] The characteristics and advantages of a multi-section dyeing apparatus 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:

[0053] FIG. 1 is a schematic view in longitudinal cross-section of an apparatus according to the present invention for ecological and sustainable dyeing, in an inert environment, with indigo and other reduction dyes, of warp chains for denim fabrics and fabrics in the system continuously, wherein the apparatus is preferably provided with three dyeing sections;

[0054] FIG. 2 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus in FIG. 1, with a possible reduced course of the yarn and/or fabric;

[0055] FIG. 3 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus in FIG. 1, in a possible embodiment with addition, on the base wall, of a further two shaped bathing cavities;

[0056] FIG. 4 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus in FIG. 1, in a possible embodiment with the heads lowered;

[0057] FIG. 5 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus in FIG. 1, in a possible embodiment with a preferred path for yarns in ropes and fabrics, such that the spraying of the dye bath takes place on both faces thereof;

[0058] FIG. 6 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus in FIG. 1, in a possible embodiment with the base wall provided with four shaped bathing cavities, and without the central manifold for collection of the dye bath;

[0059] FIG. 7 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus in FIG. 1, in a variant of the embodiment in FIG. 3;

[0060] FIG. 8 is a schematic view, in longitudinal cross-section, of the single tank of the dyeing apparatus according to the invention, in a possible embodiment with two sections and without the collection manifold of the dye bath; and

[0061] FIG. 9 is a table comparing the technical characteristics of the dyeing apparatus according to the present invention and those of the single dyeing apparatuses for the yarn warps for denim fabrics illustrated in the aforementioned patent documents.

[0062] It is specified that the following description and the appended figures do not illustrate, since they are well known to persons skilled in the art, numerous components, accessories and instruments with which all dyeing apparatuses are normally provided, such as for example regulators for the level of the dye bath, thermoregulation units, containers for preparation and recuperation of the dye bath and supply of auxiliary products, automatic dosing systems, command and control instruments, etc. It is also specified that the appended figures illustrate hydraulic circuits, provided with respective pumps and valves, which will not be described in detail hereinafter, since they are also well known to persons skilled in the art.

[0063] The figures show some possible embodiments of the apparatus for dyeing of yarns and/or fabrics according to the present invention, indicated overall with the reference number 10. The dyeing apparatus 10 is designed to carry out the dyeing, with a dye bath B which can preferably be based on indigo or other reduction dyes, of at least one continuous textile support 100 in the form of yarns and/or fabrics in general, such as for example the warp chains for denim fabrics. The dyeing apparatus 10 comprises a single tank 12 with a parallelepiped shape, inside which the textile support 100 is moved. The tank 12 is provided in its interior, in sequence, with: [0064] at least one first shaped cavity 14, which is obtained near to the bottom wall 16 of the tank 12 and at a first head 22 of the tank 12, which is internally provided with at least one return roller 18 for the textile support 100 entering the tank 12 and is configured to be at least partially filled with a predefined quantity of dye bath B. This predefined quantity of dye bath B mainly has a watertight function between the surrounding environment and the tank 12; and [0065] at least one first internal partition wall 20, which is positioned near the first head 22 of the tank 12, which is integral with the side walls of said tank 12 and is configured to be immersed in the lower part in the dye bath B of the first shaped cavity 14 for helping the watertight function.

[0066] Inside the tank 12, downstream from the first shaped cavity 14 and the first internal partition wall 20, there are thus provided one first dyeing compartment 24A and at least one second dyeing compartment 24B, 24C within which the textile support 100 is not in any way immersed in the dye bath B. Each dyeing compartment 24A, 24B, 24C comprises at least one return roller 26A, 26B, 26C for the textile support 100, arranged to guide the movement of said textile support 100 vertically or horizontally within the respective dyeing compartment 24A, 24B, 24C, at least one dispensing device 28A, 28B, 28C, preferably of the cascade type, arranged to dispense the dye bath B on the textile support 100, and at least one squeezing device 30A, 30B, 30C with opposite idle rollers, placed at the exit of the respective dyeing compartment 24A, 24B, 24C and configured to dehydrate at least partially the textile support 100 leaving the respective dyeing compartment 24A, 24B, 24C and before entering the following dyeing compartment 24A, 24B, 24C or before leaving the tank 12.

[0067] In the embodiments of the dyeing equipment 10 in FIGS. 1 to 7, there are provided three distinct dyeing compartments 24A, 24B, 24C, inside the tank 12. In the embodiment of the dyeing apparatus 10 in FIG. 8 on the other hand, there are provided two distinct dyeing compartments 24A, 24B inside the tank 12. The number of dyeing compartments inside the tank 12 can in any case vary according to requirements.

[0068] Inside the tank 12, downstream from the dyeing compartments 24A, 24B, 24C, there are thus also provided in sequence: [0069] at least one second shaped cavity 32, which is obtained near the bottom wall 16 of the tank 12 and at a second head 34 of the tank 12 opposite to the first head 22, internally provided with at least one return roller 36 for the textile support 100 leaving the tank 12 and configured to be at least partially filled with a predefined quantity of dye bath B. Similarly to the first shaped cavity 14 therefore, the predefined quantity of dye bath B in the second shaped cavity 32 has mainly a watertight function between the tank 12 and the surrounding environment; and [0070] at least one second internal partition wall 38, which is positioned near the second head 34 of the tank 12, which is integral with the side walls of the tank 12 and is configured to be immersed in the lower part in the dye bath B of the second shaped cavity 32 for helping the watertight function.

[0071] The dyeing apparatus 10 comprises at least one lid 40A, 40B, 40C, which engages in a watertight manner with the internal partition walls 20, 38 and the side walls of the tank 12, to close the tank 12 at the top and insulate the dyeing compartments 24A, 24B, 24C from the surrounding environment in a watertight manner. In the embodiments of the dyeing apparatus 10 in FIGS. 1 to 8, a single lid 40A, 40B, 40C is preferably provided for each of the dyeing compartments 24A, 24B, 24C contained in the tank 12.

[0072] Downstream from the tank 12, and thus outside this tank 12, the dyeing apparatus 10 also comprises at least one squeezing and pulling device 42 with opposite motorized rollers, which is configured to simultaneously pull the textile support 100 and extract excess liquid from this textile support 100 once it has exited from the tank 12. The dyeing apparatus 10 also comprises a hydraulic system 46, provided with at least one container 48, which is designed for the storage, circulation and supply of the dye bath B to each dispensing device 28A, 28B, 28C and inside each of the shaped cavities 14, 32 of the tank 12. The container 48 is advantageously in turn provided with means for thermal regulation 58 of the dye bath B. These thermal regulation means 58 can be constituted by one or more heating/cooling units, such as for example pipe coils, with cooling of the dye bath B.

[0073] The tank 12, with a parallelepiped form, preferably extends horizontally. Again preferably, the bottom wall 16 of the tank 12 is shaped such as to form, in addition to the first shaped cavity 14 and the second shaped cavity 32, which are in perimeter positions of this tank 12, also a central collection manifold 50 for the dye bath B. More specifically, on the bottom wall 16 of the tank 12, in a substantially intermediate position between the first shaped cavity 14 and the second shaped cavity 32, there is obtained at least one manifold 50 for collection of the dye bath B dispensed by the dispensing devices 28A, 28B, 28C of each dyeing compartment 24A, 24B, 24C. The collection manifold 50 is hydraulically connected to the hydraulic system 46 and to the corresponding container 48, such as to contribute to the recirculation of the dye bath B to the dispensing devices 28A, 28B, 28C.

[0074] As shown in the embodiments of the dyeing apparatus 10 in FIGS. 1-5 and 7, the bottom wall 16 of the tank 12 can preferably be provided with portions which are inclined relative to a horizontal plane, and descend from each shaped cavity 14, 32 towards the central collection manifold 50. By this means, the central collection manifold 50 can collect the dye bath B coming from the cascade dispensing devices 28A, 28B, 28C and from any overflows of the shaped cavities 14, 32, and then put it back into circulation through the hydraulic system 46.

[0075] In FIG. 8, the bottom wall 16 of the tank 12 can preferably be provided with portions which are inclined relative to a horizontal plane, which, from the centre of the tank 12 itself, convey the dye bath B dispensed by the cascade dispensing devices 28A, 28B, 28C to the shaped cavities 14, 32 which are hydraulically connected to the hydraulic system 46.

[0076] In the embodiments of the dyeing apparatus 10 in FIGS. 1-3 and 5-8, the opposite heads 22, 34 of the tank 12 have a height which is substantially equal to the height of the corresponding internal partition walls 20, 38. In the embodiment of the dyeing apparatus 10 in FIG. 4, on the other hand, the opposite heads 22, 34 of the tank 12 are lowered relative to the corresponding internal partition walls 20, 38. In other words, in this embodiment, the opposite heads 22, 34 of the tank 12 have a minimum height necessary, together with the bottom wall 16, to close each shaped cavity 14, 32 of the tank 12.

[0077] Independently from the height of the opposite heads 22, 34 of the tank 12, each internal partition wall 20, 38 can be provided at the top with a respective channeled profile 52, which, by being connected to corresponding transverse channeled profiles of the tank 12 (not shown), form a watertight peripheral receptacle for the upper lids 40A, 40B, 40C, which are preferably removable from the tank 12. The hydraulic seals of the lids 40A, 40B, 40C can also be replaced by packing. As previously stated, by being immersed at the bottom of the dye bath B of the respective shaped cavities 14, 32, the internal partition walls 20, 38 ensure that, as well as bathing the textile support 100 entering into and exiting from the tank 12, these shaped cavities 14, 32 carry out the main function, in combination with an upper network of perimeter and transverse channels, of a hydraulic barrier which is necessary in order to make the tank 12 inert. In fact, the hydraulic system 46 can be provided with at least one circuit 54A, 54B for supply to each dyeing compartment 24A, 24B, 24C of an inert gas N, preferably constituted by nitrogen, such as to carry out the dyeing of the textile support 100 in an atmosphere which is completely free from oxygen, or with a predetermined and controlled residue of oxygen, in other words in a substantially inert environment. In detail, as shown in the appended figures, a first circuit 54A can be provided for supply of the tank 12, and a second circuit 54B for supply of the container 18.

[0078] Preferably, as shown in all the embodiments of the dyeing apparatus 10 in the appended figures, each dispensing device 28A, 28B, 28C is positioned at the point of tangency between a corresponding lower return roller 26A, 26B, 26C and the textile support 100 at the input, around this lower return roller 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 roller 26A, 26B, 26C, i.e. at the point of maximum hydrodynamic performance, and thus the point of greatest interchange between the dye bath B and the textile support 100. Again preferably, each dispensing device 28A, 28B, 28C is constituted by a non-clogging cascade spraying device, which has a width substantially equal to, or greater than, the width of the textile support 100 moved within the tank 12.

[0079] The squeezing device 42 with opposite motorised rollers can preferably be constituted by a so-called foulard with pneumatic pressure. Downstream from this foulard 42, there are provided one or a plurality of devices 44 for blowing of air, which does or does not have oxygen added to it, in order to increase the level of oxidation of the textile support 100 once exiting from the tank 12 has taken place.

[0080] As previously stated, the dyeing apparatus 10 according to the present invention is advantageously provided with further devices which are configured to improve the dyeing capacity of the textile support 100. At least one of the shaped cavities 14, 32 of the tank 12 is in fact provided with a corresponding ultrasound generator 56, which is designed to increase the bathing effect of the dye bath B contained in this shaped cavity 14, 32. In addition, the container 48 is advantageously provided with means 58 for thermal regulation of the dye bath B, constituted for example by at least one set of pipe coils for cooling of this dye bath B, such as to increase further the colour performance of the dye bath B contained in the container 48, especially in the case when this dye bath B is based on indigo.

[0081] It has thus been shown that the multi-section dyeing apparatus according to the present invention fulfils the objectives previously set out. In practice, the multi-section dyeing apparatus according to the present invention, which is preferably configured to operate in an inert environment with indigo and other reduction dyes, and is provided with a single tank, is very simple, operatively very convenient and easy to control and maintain, but above all has a cost which is drastically lower than that of the apparatuses according to the aforementioned patent documents, it not only incorporates all the advantages proclaimed thereof, but adds to these others, as well as providing greater operative flexibility and better colour performance. A systematic comparison between the technical characteristics of a preferred embodiment of the multi-section dyeing apparatus according to the present invention and the corresponding technical characteristics of the dyeing apparatuses of the warp chains for denim fabrics according to the aforementioned patent documents can be seen in the table in FIG. 9.

[0082] With reference on the other hand to the multifunctional fabric dyeing system illustrated in document WO 2020/053677 A1, it is emphasised that the multi-section dyeing apparatus according to the present invention is, in fact, simply a dyeing tank, preferably for warp chains for denim fabrics, which operates continuously and in one direction, in an inert, ecological and economical environment. As a result of its particular characteristics, in a single unit or plurality of units, the multi-section dyeing apparatus according to the present invention advantageously replaces the eight or more dyeing tanks which normally constitute part of the traditional lines for continuous dyeing with indigo and other reduction dyes, the composition of which on average consists of 3-4 pre-treatment tanks, 8-10-dyeing tanks and 3-4 post-treatment tanks. The multi-section dyeing apparatus according to the present invention is not autonomous, or multifunctional, or two-way, but simply carries out continuously the single dyeing phase.

[0083] As a result of its particular structural and functional characteristics, the multifunctional dyeing system illustrated in document WO 2020/053677 A1 permits maximum operative flexibility, and many advantages, as well as fast deliveries of dyed fabrics, however always limited to batches of small lengths. On the other hand, the multi-section dyeing apparatus according to the present invention modernises, rationalises, and makes ecologically sustainable the dyeing of warp chains for denim fabrics on the traditional continuous dyeing lines, normally used for batches of yarn with long lengths. These apparatuses can be used both in newly constructed dyeing lines, and to modernise existing dyeing lines.

[0084] The structure of the multifunctional fabric dyeing system illustrated in document WO 2020/053677 A1 is quite complex, since this dyeing system comprises three distinct tanks, which can also be used individually and alternatively for different complementary treatments with different products, as well as using large volumes of dye bath. This requires appropriate hydraulic circuits, control instruments and supply containers for each tank, as well as their completion also with a foulard to pull the fabric at the entry and/or to dehydrate it between one tank and another, as well as rollers/unrollers and other complementary tooling. On the other hand, the multi-section dyeing apparatus for warp chains for denim fabrics according to the present invention has a very simple structure: in practice there is a single tank with a shaped base, which operates always and simply with a single dye bath dispensed by the cascade dispenser devices, and has a greatly reduced volume. This dye bath is supplied, kept in circulation and controlled by a single supply container.

[0085] In the multifunctional dyeing system for fabrics illustrated in document WO 2020/053677 A1 the phase of dyeing with indigo involves, alternatively, impregnation with lengthy immersion and a full volume of dye bath in the first tank, a lengthy time of stay in the second tank (for the diffusion/fixing of the dye) and a second impregnation with brief immersion, with a reduced volume of dye bath, in the third tank. The single tank of the multi-section dyeing apparatus for warp chains for denim fabrics according to the present invention operates on the other hand by using simply a new and innovative operative method, constituted by a plurality of sequential impregnations with the dye bath, interspersed by squeezing in order to refill the interstitial bath. There are no immersion tanks, or a chamber for diffusion/fixing of the dye.

[0086] In the multifunctional dyeing system for fabrics illustrated in document WO 2020/053677 A1 the dyeing operation, together with all the other complementary phases required by the operative cycle, is carried out by immersion of the fabric in the different dye baths necessary, which have a large volume. The single tank of the multi-section dyeing apparatus according to the present invention operates exclusively for the single dyeing phase of the warp yarn, but without the immersion of this yarn in the dye bath. In fact, the dye bath is uniformly supplied, at the NIP of all the lower accompaniment cylinders, by means of a plurality of free cascade sprayers, placed fully facing the yarn. As well as permitting an enormous reduction of the volume of dye bath, with all the inherent advantages thereof, this system permits a considerable increase in the recycling of the dye bath itself, to the advantage of the interchange with the fibre, with better penetration and regularity of the dye.

[0087] With reference to the embodiment of FIG. 8C of document WO 2020/053677 A1, it is specified that this embodiment has the same technical characteristics as the corresponding embodiments shown in all the other figures of this document. This embodiment shows simply a multifunctional system for dyeing of fabrics in the specific variant with a combined vertical/horizontal course of the fabric. This course is necessary in order to be able to carry out the dyeing on both faces of the fabric, by means of application of the dye with various systems which do not require immersion of the fabric itself in the tanks, as is the case on the other hand for all the other embodiments of the system. The purpose of this specific embodiment of the system is to be able to reduce drastically the volume of dye bath, with the undeniable advantages thereof. In any case, this specific embodiment also of the system according to document WO 2020/053677 A1, which may seem simpler than the other embodiments, also has its complexity and operative complication caused by the fact that, in order to be able to operate in the modes specified, it is necessary to use the dye bath simultaneously in two different physical forms, i.e. necessarily liquid, in the small head tanks for the watertightness, and in other forms for the dyeing, for which the system needs to be completed with specific supplementary apparatuses, such as generators and distributors under foam nitrogen, systems for pressurisation with nitrogen of the spray nozzles, devices for preparation and distribution under nitrogen of the spreading pastes, and scraping. As well as their high cost, these additional apparatuses require particular and constant operations of maintenance and above all cleaning, since they are subject to possible obstructions.

[0088] On the other hand, with reference to the multi-section dyeing apparatus for the warp chains for denim fabrics according to the present invention, the addition of the thermal regulation means 58 to the container 48 for circulation of the dye bath cannot be considered to be for the purpose specified in the system according to document WO 2020/053677 A1, but to take advantage of a particular characteristic of indigo dye, which, at a temperature of approximately 15 C. has the maximum affinity with cellulose fibre, and therefore makes it possible to obtain a substantially better colour performance. This is possible and advantageous, in view of the greatly reduced volume of the dye bath used in the individual tank of the multi-section dyeing apparatus according to the present invention. Again, because of the greatly reduced volume of dye bath used in the individual tank of the multi-section dyeing apparatus according to the present invention, it is then advantageous to apply an ultrasound generator 56 to the two shaped cavities 14, 32, in order to increase the bathing effect.

[0089] In short, the multi-section apparatus for dyeing of warp chains for denim fabrics according to the present invention, which apparatus is preferably configured to operate in an inert environment, using indigo and other reduction dyes, complies fully with the new industrial, creative, economical and ecological demands which require production changes, as well as economy of management and environmental sustainability.

[0090] The scope of protection of the invention is thus defined by the appended claims.