(19)
(11) EP 4 230 782 A2

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
23.08.2023 Bulletin 2023/34

(21) Application number: 23165097.9

(22) Date of filing: 14.09.2021
(51) International Patent Classification (IPC): 
D06B 3/08(2006.01)
D06B 5/24(2006.01)
D06B 19/00(2006.01)
D06B 5/20(2006.01)
D06B 5/26(2006.01)
D06B 21/02(2006.01)
(52) Cooperative Patent Classification (CPC):
D06B 5/20; D06B 5/24; D06B 5/26; D06B 19/0017; D06B 21/02; D06B 23/14; D06B 23/205; D06B 1/02; D06B 23/04; D06B 15/10; D06B 3/08; D06B 3/30
(84) Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME
Designated Validation States:
KH MA MD TN

(30) Priority: 07.10.2020 IT 202000023629

(62) Application number of the earlier application in accordance with Art. 76 EPC:
21772841.9 / 4225984

(71) Applicant: Master S.r.l.
20846 Macherio (MB) (IT)

(72) Inventor:
  • RONCHI, Francesco
    20845 SOVICO (MB) (IT)

(74) Representative: Ottazzo, Marco Francesco Agostino et al
Giambrocono & C. S.p.A. Via Rosolino Pilo, 19/b
20129 Milano
20129 Milano (IT)

 
Remarks:
This application was filed on 08.05.23 as a divisional application to the application mentioned under INID code 62.
 


(54) MACHINE FOR ENVIRONMENTALLY SUSTAINABLE DYEING, WITH INDIGO AND OTHER DYES, OF HANK YARNS AND/OR READY-MADE GARMENTS


(57) A description is provided of a dyeing machine comprising: a dyeing apparatus provided with a casing enclosing a dye compartment and a hermetically sealed hatch which permits access to the dye compartment; a support frame, which rotates within the dye compartment; at least one tank containing a dye bath; a hydraulic circuit, which is connected hydraulically to each tank and to the dyeing apparatus in order to supply the dye bath from each tank to the dye compartment and vice versa; and a plurality of support means for the hank yarns and/or the ready-made garments to be dyed. The support means are mounted on the support frame and are accessible via the hatch. Both the casing and the support frame have a preferably circular form in transverse cross-section, such that the casing has a cylindrical frontal wall and the dye compartment has a cylindrical form. The hatch is provided on the cylindrical frontal wall of the casing and the support means are disposed on the support frame according to a configuration which is preferably circumferential with respect to a central axis of rotation of the support frame, and the means are placed in the vicinity of the inner surface of the cylindrical frontal wall of the casing. The hydraulic circuit comprises one or more circuits for supply of nitrogen and air, which are connected hydraulically to each tank and to the dye compartment, such as to be able to supply them with nitrogen.




Description


[0001] The present invention relates in general to a machine for treatment of yarns and fabrics, and, in particular, a machine for environmentally sustainable dyeing, with indigo and other dyes, of hank yarns and/or ready-made garments. More particularly, the present invention relates to a machine and a method for dyeing which preferably operate in an inert environment, under nitrogen, with indigo and other reduction dyes.

[0002] For the sake of greater clarity and simplicity of explanation, the dyeing machine according to the present invention will be described by way of non-limiting example, with reference only to dyeing of hank yarns using indigo dye. It is however specified that, in addition to the foregoing, the dyeing machine according to the present invention is also suitable for dyeing of hanks of any fibre using the appropriate different classes of dyes, as well as, it will be appreciated subject to use of a suitable inner rotary material-carrier frame, for dyeing of ready-made garments such as socks, sweaters, jeans and the like, whether made of knitwear or fabric.

[0003] For millennia, natural indigo, extracted by grinding numerous plants of the indigo genus and various others, common in India and Java, was the blue colour par excellence for wool, linen, silk and cotton. In 1883, the German chemical company BASF determined the formula of indigo, and, a few years later, it put on the market the new synthetic indigo, with a substantially lower cost, which soon replaced the natural type. However, after the discovery in 1908 by the German chemical company CASSELLA of the blue dye "Hydron", which is easier to apply, has better fastness and a significantly lower cost, within a few years indigo fell completely into disuse.

[0004] Nevertheless, the particular characteristic of indigo, i.e. the fact that after repeated washings its blue tends to lighten until it becomes an increasingly brighter light blue, in contrast with the new "Hydron" blue which on the other hand tends to become opaque, meant that, about 50 years later, indigo returned to favour with the initial successes of jeans, the trousers which, from a humble working garment, became synonymous with leisure time, to the extent that they rose to the ranks of high fashion and became a clothing classic worldwide.

[0005] Nowadays, as was the case in the past, dyeing of yarns using indigo, which is indissolubly associated with jeans, as a result of changed social requirements, the continual development of fashion, etc., is once again required in order to complete, modernise and make available the production of new articles of clothing. This is because indigo is the only dye with the particular characteristic that, over a period of time, after various washings, it makes the colour tone of garments to be produced, as is the case for classic jeans, increasingly lighter, but also very bright, and therefore gives them a very pleasing appearance.

[0006] 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 use of the vegetable dye up to the present, over a hundred years since it was synthesised. As a result of its relatively small molecule and low affinity with cellulose fibre, in order to be applied indigo dye must not only be reduced in (leuco compound) alkaline solution, but also needs to be subjected to a plurality of impregnations, alternating with wringing and subsequent oxidations in air. In practice, a medium or dark shade is obtained only by subjecting the yarn to a first dyeing operation (constituted in sequence by the phases of impregnation, squeezing and oxidation), followed immediately by a plurality of overdyeing operations, which are all the more numerous the darker the shades and the greater the colour fastness required.

[0007] However, whereas this working methodology has easily been applied to continuous dyeing of denim fabric in order to produce jeans, since it is carried out on lines constituted by a sequence of dyeing tanks, each provided with devices for squeezing and oxidation, the same working methodology is not as easy, or rather it is very difficult to apply, using the traditional discontinuous dyeing machines of the type known as "batch", for various garments made from hank yarn. Undoubtedly, the very lengthy period of complete lack of use of indigo dye except for jeans, together with the lack of interest in new particular uses, has not stimulated research and experimentation in this respect.

[0008] The product which lends itself best to the methods for discontinuous (batch) dyeing with indigo, out of a vast range of cotton yarns and other fibres, is that of the hank type. Dyeing of yarns in hank form is perhaps the oldest system (albeit with continuous technological modernisation) which, for various reasons and technical requirements, is still extensively in use utilising various classes of dyes (excluding indigo).

[0009] In the past, in the case of indigo, the hanks were dyed in wooden tanks, immerse suspended on special rods shaped in the form of an inverted omega, such as to keep these hanks completely immersed in the dye bath, in order to prevent oxidation of the dye. The position of the hanks was changed manually, on these rods, which in turn were moved from one side of the tank to the other. When the dyeing was completed, the hanks were wrung out and exposed to the air for oxidation. These operations had to be repeated several times depending on the colour shade required.

[0010] Dyeing of hank yarns is still in use, wherein it is a product where the yarn is wound freely, softly, regularly and voluminously, so as to keep all of the characteristics thereof unaltered. These qualities are greatly valued in the knitwear sector, especially for fine and delicate fibres. Furthermore, hanks are a product wherein the yarn is wound in the form of a loop, and thus in the only condition which, by means of a particular machine, allows the cotton hanks to be tensioned during the mercerisation treatment, which is a particularly important treatment for the knitwear and shirt production sectors.

[0011] Mercerisation, as it is known universally in honour of its inventor, John Mercer, is a process by means of which, through the action of concentrated caustic soda and at a low temperature, the cotton yarn is subjected to considerable shrinkage which, if prevented, gives rise to a silky sheen of the fibre. In practice, the more strongly the shortening of the yarn is generated by means of the caustic soda, and the more efficiently this shortening is prevented, the better the sheen of the yarn which is obtained.

[0012] As well as providing the yarn with the particular sheen, the mercerisation treatment also gives it greater mechanical strength, with improvement of the resilient "coating", in addition to the important property of being dyed more intensely than the same yarn when not mercerised, thus resulting in a significant saving of dye.

[0013] For all of these particular characteristics, mercerised yarn is of great importance for the sectors of knitwear and shirt production which, if they have the possibility of being able to dye also with indigo, have the opportunity to expand considerably the availability of new products, which are in great demand in the fashion industry, resulting in revival of the corresponding markets in times of crisis. If yarn dyed with indigo is well fixed, and above all does not shed dust, even when it is not mercerised it is of particular interest for the potential production of a vast range of new types of smooth and worked fabrics and knitted work, as well as, in addition to conventional plushes, to make available also other sportswear articles and knitted jeans, which are in demand because they are far more convenient, easier to put on, and more comfortable than the traditional type.

[0014] The machines available worldwide at present for dyeing of hanks consist almost entirely of the "cabinet" type, so-called because of the vertical parallelepiped form of these machines, where the hanks, suspended on a series of rods, with adjacent blocks and on one or two levels, are completely immersed in the dye bath, and kept in two-way circulation, i.e., down/up and up/down, by means of a pump. These machines operate at full volume with a mean ratio of approximately 1 to 13 between the weight of the yarn and the volume of the dye bath. These are machines which are in no way suitable for dyeing with indigo because of the subjective structural difficulties and need for many manual operations, with consequent very high costs, and above all quality results which are not optimal.

[0015] In fact, in order to be able to dye with indigo using the traditional process involving successive phases of impregnation, squeezing and oxidation, after the first dyeing operation it would be necessary to empty the cabinet, recuperating the dye bath, extract the hanks, spin them, and oxidise the dye in air. The hanks would then have to be reintroduced into the cabinet in order to repeat all the phases again, on further occasions, until the desired colour shade was obtained. This shows clearly that, in the present cabinet dyeing machines, in practice it is impossible to dye hanks with indigo, except by carrying out a single cycle, to obtain very light shades, with many manual operations, and with quality results which are not excellent.

[0016] On this basis, even though it may seem absurd, it must be admitted that, compared with the modern system of dyeing in cabinet machines, in the case of indigo the old manual system would be simpler and less intricate, with the tank totally immersed in the hanks, obviously with all the operations carried out automatically. However, this is a system which it would be unthinkable to create nowadays.

[0017] Even though they were not specifically designed for dyeing with indigo, around 1890/1895 two hank dyeing machines were developed which modernised the old tank system, i.e. with the dye bath stationary and with manual movement and translation of the rods with the hanks. Although the dye bath was always stationary, these two dyeing machines made it possible to place the hanks on rods disposed in the form of spokes on a rotary hank-carrier. One of these two machines was produced towards the end of the 19th century by the German textile engineering company ZITTAUER. The other machine is illustrated on page 691 of the Italian monthly review "LANIERA" of October 1987.

[0018] A third hank dyeing machine, similar to the above two machines from a design point of view, is illustrated in document DE 855684 C. In this dyeing machine, the hank carrier is however divided into two sections. As well as being altogether unsuitable for dyeing with indigo, like the two above dyeing machines the dyeing machine which is illustrated in document DE 855684 C has many design and functional problems, i.e.:
  • it has an irrational system for loading/unloading of the hanks, which is carried out from above, with the hanks horizontal, meaning that it is necessary to take in hand two long rods simultaneously, and therefore two operators are needed, one for both sides of the dyeing machine, who must be able to move on lateral platforms;
  • the rods are designed for loading of 16 hanks with a length of approximately 2 m (in dyeing cabinets, the largest rods are 1 m long, and each support 8 x 500 g hanks), which are therefore difficult to handle, they are heavy, and need to be moved by two operators;
  • the large thickness determined by the seven rows of hanks, contained in both of the two rotary sectors of the dyeing machine, gives rise to a considerable difference in the percentage of residual humidity between the various hanks in the spinning phase, because of the significant difference in peripheral speed between the inner and outer hanks, resulting in negative effects on the dyeing quality;
  • the hank-carrier rods, which are usually constituted by tubes with a small cross-section, but are 2 m long and hold 8 kg of dry yarn which becomes very heavy when wet, will almost certainly bend during the spinning, instead of remaining linear;
  • at the end of the dyeing, a stoppage time is allowed for dripping: this is a serious mistake, since even after the spinning there will always be a difference in residual humidity between the high part and the low part of the hanks;
  • two thick sections of hank which rotate one way have a very significant impact on the dye bath, which is static, and impede the necessary regular interchange of the bath with the fibre, meaning that uniformity of dyeing is not guaranteed;
  • the ratio between the volume of the dye bath and the weight of the yarn is very high (presumably approximately 20 to 1), taking into consideration the fact that in practice the dye bath occupies half the volume of the casing of the dyeing machine;
  • the dyeing machine does not have heating/cooling pipe coils for the dye bath; however, since this is a dye bath with a large volume, it is presumably uneconomical to use a cooling system which takes the temperature of the dye bath to 15°C, which is the temperature of maximum affinity of indigo dye, or to use an ultrasound generator to increase the colour yield further.


[0019] Even if the above-described problems were overcome from an operative point of view, the dyeing machine illustrated in document DE 855684 C would still have an insurmountable problem in common with the two other aforementioned dyeing machines, which make it altogether unsuitable for dyeing with indigo. In fact, during the dyeing, some of the spokes with the hanks (in the two aforementioned dyeing machines) and one of the two hank-carrier sectors (in the dyeing machine illustrated in document DE 855684 C) still remain alternately in contact with the air, and therefore in a condition of detrimental oxidation of the bath for dyeing the respective hanks.

[0020] Further dyeing machines are illustrated in documents WO 96/17990 A1 and JP S62 6966 A. However, these dyeing machines are altogether unsuitable for dyeing with indigo dye either of hank yarns or ready-made garments. In fact, during the dyeing, in these machines most of the textile material to be dyed always remains alternately in contact with the air, and therefore in a condition of detrimental oxidation of the respective impregnation bath. It should be noted that, because of its design and operative characteristics and the particular system of positioning of the hanks, the dyeing machine illustrated in document WO 96/17990 A1 cannot be used for industrial production. In addition, the dyeing machine illustrated in document JP S62 6966 A does not have either support devices for hanks stretched between two arms, or support devices for hanks suspended on standard rods. Without these support devices, the yarn of the hanks which are placed in the cells of the rotary basket, which is free to move and roll, would become matted and tangled, thus making the subsequent disentangling operation, and therefore use of the yarn itself, impossible. In fact, the dyeing machine which is illustrated in document JP S62 6966 A appears to be a conventional rotary dyeing machine for ready-made garments, using a principle which for over 50 years has also been applied universally to both industrial and domestic washing machines.

[0021] The object of the present invention is thus to provide a machine for environmentally sustainable dyeing with indigo and other dyes, of hank yarns and/or ready-made garments, which can eliminate the aforementioned disadvantages of the prior art in a manner which is extremely simple, economical, ergonomic, ecological and particularly functional.

[0022] In detail, an object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which permits execution of the entire dyeing cycle sequentially, directly in its interior and in an inert environment, such as to provide a series of not only economic, but also quality advantages in terms of fastness, fixing of the dye, and brightness of the dyeing.

[0023] Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which makes it possible to reduce the number of dyeing phases to a single one.

[0024] Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which can operate with the minimum quantity of dye bath possible, such as to reduce substantially the consumption of energy, water and chemical products (caustic soda and sodium hydrosulphite), and consequently reduce the production costs.

[0025] Another object of the present invention is to provide a machine for dyeing of hank yarns and/or ready-made garments which, under nitrogen with indigo and other reduction dyes, or in contact with the air with other classes of dyes, can operate with a very low ratio between the weight of the yarn and the volume of the dye bath, with the bath closed, with or without internal recirculation, and with or without upper sprinklers, with the material-carrier frame with one or two stages rotating slowly in both directions.

[0026] Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which makes it possible to carry out exclusive dyeing cycles with high-concentration dye baths, and also at a low and/or high temperature.

[0027] Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which makes it possible to recuperate used dye baths containing indigo, such that, after titration and topping up of the various components, these dye baths can be reused.

[0028] Another object of the present invention is to provide a machine for dyeing with indigo of hank yarns and/or ready-made garments which uses the minimum possible volume of dye bath, so as to render economical the possibility of applying a system for cooling of the dye bath itself to approximately 15°C in order to take advantage of the maximum affinity with the fibre, as well as the possibility of applying an ultrasound generator, in order to increase the colour yield further.

[0029] A further object of the present invention is to provide a machine for dyeing with indigo of hank yarns which is particularly suitable for mercerised yarns for knitwear, shirt production and other particular uses.

[0030] Yet another, very important object of the present invention is to provide a machine for dyeing with indigo and other dyes of hank yarns which, using the same hank-carrier rods as the dyeing cabinets according to the prior art, and with the same vertical loading system, creates advantageous operative interchangeability with these.

[0031] These objects according to the present invention are achieved by providing a machine for dyeing with indigo and other dyes of hank yarns and/or ready-made garments, as described in claim 1.

[0032] Further characteristics of the invention are indicated by the dependent claims, which are an integral part of the present description.

[0033] The dyeing machine according to the present invention extends horizontally, and is designed to carry out dyeing of hanks and/or ready-made garments under nitrogen or in contact with the air (at atmospheric pressure or under static pressure), with partial filling and a reduced volume of the dye bath, which contains in its interior one or more material-carrier frames (for hanks on standard rods, which are common to all the dyeing cabinets according to the prior art) rotating on a single axis with a variable speed and in both directions. This dyeing machine can thus execute in its interior the entire dyeing operative cycle both with indigo, and with other classes of dyes.

[0034] The dyeing machine according to the present invention does not have any of the aforementioned disadvantages of the dyeing machines of the known type, since it operates in an inert environment (preferably under nitrogen), in a rational, ergonomic, and environmentally sustainable manner. The fact that it operates in the particular condition of an inert environment (preferably under nitrogen), with a very low ratio between the weight of the yarn and the volume of the dye bath, equal to approximately 1 to 4, makes it possible to execute completely in its interior not only dyeing using the traditional operative method, but also dyeing with an innovative process which is monophase and/or repeatable, without intermediate oxidation, as well as individual special operative cycles with high-concentration dye baths at a low and/or high temperature, which cannot be carried out on traditional dyeing machines. All of this is performed very rapidly and in an environmentally sustainable manner.

[0035] The dyeing machine according to the present invention also has the practical advantage of using the same hank-carrier rods as those which are commonly used by all the cabinet dyeing machines according to the prior art, with which it can therefore operate in perfect synergy.

[0036] The characteristics and advantages of a machine for dyeing of hank yarns and/or ready-made garments 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 vertical transverse cross-section of a first embodiment of a machine for dyeing of hank yarns and/or ready-made garments according to the present invention, designed in particular for dyeing with indigo in an inert environment;

figure 2 is a schematic view in vertical longitudinal cross-section only of the dyeing apparatus of the machine in figure 1, inside which there is fitted such as to rotate a single rotary support frame to accommodate hank-carrier rods;

figure 3 is a schematic view in vertical longitudinal cross-section only of the dyeing apparatus of the machine in figure 1, inside which there are fitted such as to rotate two rotary support frames to accommodate hank-carrier rods;

figures 4A and 4B are schematic views in vertical transverse cross-section of two possible variants of the machine for dyeing of hank yarns and/or ready-made garments according to the present invention, wherein the support frame is designed to accommodate two different types of support means for ready-made garments; and

figure 5 is a schematic view in vertical transverse cross-section of a second embodiment of a machine for dyeing of hank yarns and/or ready-made garments according to the present invention, designed in particular for dyeing in air with dyes different from indigo.



[0037] 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 machines are normally equipped, such as, for example, dye bath level regulators, thermal regulation units, preparation containers, units for recovery of the dye baths and supply of auxiliary products, automatic metering 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 these are also well known to persons skilled in the art.

[0038] The figures show two possible embodiments of the machine for dyeing of hank yarns and/or ready-made garments according to the present invention. The dyeing machine is indicated as a whole by the reference number 10, and is designed to carry out the dyeing of hank yarns and/or ready-made garments both with indigo and other reduction dyes, in an inert environment and preferably under nitrogen, as well as with other classes of dyes, in air.

[0039] The dyeing machine 10 comprises at least one dyeing apparatus 12 provided with:
  • a casing 18 enclosing at least one dye compartment 20; and
  • at least one hermetically sealed hatch 22, which is provided on said casing 18 and permits access to the dye compartment 20.


[0040] The dyeing machine 10 also comprises at least one support frame 14, which is mounted such as to rotate within the dye compartment 20 and is designed to rotate, by means of at least one rotation pin 16, around a central axis of rotation A which is substantially horizontal and passes via the rotation pin 16. The rotation of the support frame 14 can be controlled, in a known manner, by one or more electric motors 58 or by other movement means suitable for the purpose.

[0041] The dyeing machine 10 also comprises at least one tank 24, 26 (figure 1), or 44, 46 (figure 5), containing at least one dye bath B and at least one hydraulic circuit 28, which is connected hydraulically to each tank 24, 26 or 44, 46, and to the dyeing apparatus 12 in order to supply the dye bath B from each tank 24, 26 or 44, 46 to the dye compartment (20) and vice versa. The dyeing machine 10 also comprises a plurality of support means 30, 32, 34 for the hank yarns and/or the ready-made garments, which means are mounted on the support frame 14 and are accessible via the hatch 22.

[0042] Both the casing 18 and the support frame 14 preferably have a circular form in vertical transverse cross-section, i.e. a cross-sectional obtained along a plane orthogonal to the central axis of rotation A of the support frame 14, such that the casing 18 has a cylindrical frontal wall and the dye compartment 20 thus has a cylindrical form. Each hatch 22 is provided on the cylindrical frontal wall of the casing 18 and the support means 30, 32, 34 are disposed on the support frame 14 according to a configuration which is preferably circumferential relative to the central axis of rotation A, and the means are placed in the vicinity of the inner surface of the cylindrical frontal wall of the casing 18, as shown for example in figures 1, 4A, 4B and 5.

[0043] Each support frame 14 is delimited by a pair of preferably circular lateral walls 36, 38 which are substantially flat, opposite one another, and disposed orthogonally relative to the central axis of rotation A. For example, figure 2 shows a dyeing apparatus 12 which is provided with a single support frame 14 (single-stage configuration). On the other hand, figure 3 shows a dyeing apparatus 12 which is provided with two distinct support frames 14, which are adjacent to one another in the direction of the central axis of rotation A (configuration with two stages). However, it is not excluded for the dyeing apparatus 12 to be provided with three or more distinct support frames 14, always disposed adjacent to one another in the direction of the central axis of rotation A.

[0044] Preferably, each hatch 22 has a width, measured along the central axis of rotation A, which is substantially equal to the distance L between the two lateral walls 36, 38 of each support frame 14. In other words, each hatch 22 is "all front", to the advantage of the loading and unloading operations of the hank yarns and or the ready-made garments into and from the dyeing apparatus 12.

[0045] In the embodiments in figures 1, 2, 3 and 5, the dyeing machine 10 is designed for dyeing of hank yarns. Each of the support means 30 is thus constituted by a rack which supports a plurality of hank-carrier rods 40 for dyeing of the hank yarns. In the variants in figures 4A and 4B on the other hand, the dyeing machine 10 is designed for dyeing of ready-made garments. Each of the support means 32, 34 is thus constituted by a perforated compartment or container provided with at least one opening 42. Each perforated compartment or container 32, 34 is designed to contain the ready-made garments and to dye them by means of passage of the dye bath B through the holes with which this perforated compartment or container 32, 34 is provided.

[0046] Solely by way of example, in the embodiments of the dyeing machine 10 in figures 1, 2, 3 and 5, designed for dyeing of hank yarns, each support frame 14 can have one or two stages. Each support frame 14 can thus preferably be designed to contain six racks 30, disposed circumferentially in a "hexagon" configuration if seen in vertical transverse cross-section (as shown for example in figures 1 and 5) and each bearing three or four rows of hank-carrier rods 40.

[0047] According to the invention, the hydraulic circuit 28 comprises one or more nitrogen and air supply circuits 50, which are connected hydraulically to each tank 24, 26 and to the dye compartment 20 with a cylindrical form, such as to be able to supply them with nitrogen N. Unlike the dyeing machines according to the prior art previously described, this technical characteristic makes it possible to dye, with indigo and other reduction dyes in an inert environment, hank yarns and/or ready-made garments inside the dye compartment 20.

[0048] The two different embodiments of the dyeing machine 10, one shown in figure 1 and the other in figure 5, are in fact distinguished by the dyeing method and the type of dye bath B used. The embodiment of the dyeing machine 10 in figure 1 is designed to carry out dyeing with indigo and other reduction dyes, in an inert environment and under nitrogen. The dyeing machine 10 thus comprises a first hermetically sealed tank 24 containing an indigo-based dye bath B and a necessary quantity of nitrogen N, and a second hermetically sealed tank 26, which is connected hydraulically to the first hermetically sealed tank 24, and acts as an auxiliary tank for the indigo-based dye bath B and for the necessary quantity of nitrogen N. In this embodiment of the dyeing machine 10, each nitrogen and air supply circuit 50 is connected hydraulically both to the first hermetically sealed tank 24 and to the second hermetically sealed tank 26. Also, in this embodiment of the dyeing machine 10, the dye compartment 20 with a cylindrical form can be provided in its interior with at least one chamber 54 which serves the purpose of a reduction plenum chamber for the volume of nitrogen N contained in this dye compartment 20 with a cylindrical form.

[0049] On the other hand, the embodiment of the dyeing machine 10 in figure 5 is designed to carry out dyeing in air with dyes different from indigo. The dyeing machine 10 thus comprises a first tank 44 which operates in air, containing a bath B for dye different from indigo, and a second tank 46 which operates in air, and is connected hydraulically to the first tank 44 which operates in air and acts as an auxiliary tank for this bath B for dye different from indigo. Consequently, in this embodiment of the dyeing machine 10, the nitrogen and air supply circuits 50 are not used.

[0050] Independently of the embodiment, the dyeing machine 10 can comprise at least one recirculation circuit 48 for the dye bath B contained in the dye compartment 20 with a cylindrical form. The dyeing machine 10 can also comprise one or more cascade sprinkler devices 52, which are connected hydraulically to the dyeing apparatus 12 by means of the hydraulic circuit 28, and are designed to sprinkle directly the dye bath B in the dye compartment 20 with a cylindrical form. The dyeing apparatus 12 and/or at least one of the tanks 24, 26 can also be provided with means 56 for thermal regulation of the dye bath B. These means 56 for thermal regulation can be constituted by one or more heating and/or cooling pipe coils of the dye bath B. The dyeing apparatus 12 can finally be provided with one or more ultrasound generators 60 in order to increase the colour yield further.

[0051] The dyeing machine 10 is thus designed to immerse the hanks or ready-made garments in the dye bath B, which occupies the lower part of the dye compartment 20. In the absence of the dye bath B, the dyeing machine 10 can also carry out the spinning directly, and, subject to discharge of the nitrogen N and intake of air, it can carry out oxidation of the hanks or ready-made garments by means of rotation of the support frame 14 around its own central axis of rotation A. Because of its particular design form, the dyeing machine 10 in fact makes it possible to dye with a very low ratio between the weight of the yarn and the volume of the dye bath B, equal to approximately 1 to 4, compared with a value of 1 to 13 of the dyeing cabinets according to the prior art, as well as to spin and oxidise the dyed yarn and/or the ready-made garments directly in its own interior.

[0052] The dyeing machine 10 can also dye in an inert environment (this is a particular and advantageous ecological technology described in documents EP 1771617 B1 and EP 1971713 B1 in the name of the same applicant, as well as in document WO 2017/208134 A1), using hank-carrier rods 40 with the same measurements as, and/or coming from, conventional cabinet dyeing machines. This interchangeability of the hank-carrier rods 40 is very important and extremely convenient, since it allows the dyeing machine 10 to be used for the purpose of increasing productivity significantly, only for the true dyeing phase of the operative cycle, whereas on the other hand the remaining initial operations (soaking up, steeping, etc.) and final operations (washing, soaping, softening, etc.) can also be carried out in the conventional cabinet dyeing machines.

[0053] The particular preferred structural form of the dyeing machine 10 and of its rotary support frame 14, i.e., provided with six independent support means 30 with a narrow thickness, and with only three or four rows of hank-carrier rods 40 has been designed in order to:
  • be able to operate sequentially, with only one of the six rotary support means 30 filled with hank-carrier rods 40 totally immersed in the minimum possible volume of dye bath B (with the advantage also of reducing drastically the energy consumption) of its various chemical products and water;
  • operate in an inert environment, under nitrogen N, such that the dye bath B present in the (non-immersed) hanks contained in the other five rotary support means 30 does not oxidise, but continues its action of diffusion and fixing in the fibre;
  • operate with the support frame 14 rotating slowly, variably and in two directions, in order to ensure the best interchange between the dye bath and fibre;
  • reduce the volume of the nitrogen N in the dye compartment 20 only to the perimeter crown thereof, thanks to the reduction plenum chamber 54, thus reducing the consumption of nitrogen N by 25%, and also with the advantage of shortening the time for rendering inert;
  • be able to dye flexibly, as required and with a variable capacity, i.e. with the hanks positioned equally well within six (in other words all), four, three or only two of the support means 30;
  • make the operations of loading/unloading of the hank-carrier rods 40 easy and ergonomic by means of the lateral hatch 22, with a single operator who does not need platforms and/or other raising equipment;
  • after the final hydro-extraction, guarantee virtually uniform residual humidity between the hanks which are suspended on the outside and in the inside of each of the support means 30 of the support frame 14.


[0054] In addition to the above particular characteristics, the fact of operating in an inert environment, preferably under nitrogen, makes it possible to modernise the known operative cycle for dyeing with indigo, constituted substantially by three operative phases which are repeated several times (impregnation of the yarn with the leuco compound, elimination of the excess dye bath contained therein, and oxidation of the dyed yarn), with the addition of a fourth operative phase, i.e., that of diffusion/fixing of the leuco compound in an inert environment. In addition, by means of operation under nitrogen, i.e., in an inert environment, the dye bath B which impregnates the hanks held by the support means 30, which emerge cyclically from this dye bath B, not only does not oxidise, but, since it remains in the leuco compound state, continues its action of diffusion and fixing in the fibre.

[0055] Operating under nitrogen not only makes it possible to shorten the operative times significantly, but also to be able to carry out innovative single-phase dyeing cycles, with dye baths at a high concentration and a high temperature, as well as to reduce by 50% to 80% the consumption of caustic soda and sodium hydrosulphite. Under nitrogen, the chemical reduction of the indigo is total and perfect, and the leuco compound is broken up into particles with a nanometric dimension. Compared with the traditional systems, this characteristic increases the dyeing capacity of the indigo, improves the penetration thereof, and intensifies the fixing thereof on the fibre, with a substantial saving of washing water and with excellent results in terms of fastness, intensity and brightness, which are essential characteristics for yarn to be used in shirt production and knitwear.

[0056] Further technical improvements are provided by the possibility, allowed by the very low volume of dye bath B, of applying thermal regulation means 56 economically. In particular, these thermal regulation means 56 can be cooling means which make it possible for example to cool the dye bath B to approximately 15°C. At this temperature, the indigo dye has the greatest affinity with the cellulose fibre, thus obtaining a better colour yield, which can be increased further by the application of one or more ultrasound generators 60.

[0057] The dyeing machine 10 according to the present invention makes it possible to implement an innovative dyeing method which comprises the following monophase operative cycle, which is replicable and is carried out totally automatically. This dyeing method should however be considered as indicative and not compulsory, since it can be adapted to various particular production requirements, as well as to the composition of the colour kitchen and/or to other particular equipment.

[0058] After having prepared in the first preparation tank 24 the entire quantity of dye bath B necessary to dye a single batch or a plurality of batches constituting an entire lot of yarn, a determined quantity of dye bath B, necessary for a batch, is transferred into the second, auxiliary tank 26. The following steps are then taken:
  1. a) through the convenient lateral hatch 22, with a single operator on the ground, loading of the hank-carrier rods 40 with the dry hanks placed vertically (which hanks can be pre-treated directly or pre-treated in dyeing cabinets according to the prior art) into the support means 30 positioned inside the dye compartment 20;
  2. b) rendering inert the dye compartment 20 (and thus the yarn) and the second, auxiliary tank 26 where the necessary quantity of dye bath B can be sent in advance, keeping it in internal recirculation and under nitrogen N;
  3. c) when a pre-set residual oxygen value is reached in the dye compartment 20, blocking the internal recirculation in the second, auxiliary tank 26 and beginning the transfer of the dye bath B into the lower part of the dye compartment 20, with the support frame 14 rotating slowly and alternately in both directions;
  4. d) dyeing the yarns in the necessary conditions and for a predetermined time (with or without internal recirculation of the dye bath B, and with or without activation of the upper cascade sprinkler devices 52), again with the support frame 14 rotating slowly and alternately in both directions;
  5. e) when the processing time has elapsed, stopping the rotation of the support frame 14 and transferring the dye bath B into the second, auxiliary tank 26;
  6. f) starting the rotation of the support frame 14 for a predefined period of time at a pre-set speed, for ejection of the interstitial dye bath from the hanks, with recovery of the interstitial dye bath itself in the second, auxiliary tank 26;
  7. g) optionally keeping the hanks under nitrogen N for a predefined period of time, with the support frame 14 rotating slowly and alternately in both directions, for the diffusion/fixing of the dye in the fibre;
  8. h) optionally repeating the operations c), d), e), f), g);
  9. i) spinning the hanks for a predefined period of time, with recovery of the extracted dye bath B in the second, auxiliary tank 26;
  10. j) isolating the dye compartment 20 from the hydraulic circuit 28 for supply/regulation of the nitrogen N;
  11. k) rendering the dye compartment 20 non-inert;
  12. l) admitting air into the interior of the dye compartment 20, with the support frame 14 rotating slowly and alternately in both directions, for a predefined period of time, such as to obtain the oxidation of the dye;
  13. m) carrying out, with or without intermediate spinning, any washing operations and/or final treatments on the hanks (which can also be carried out in dyeing cabinets according to the prior art, in order to increase the productivity of the dyeing machine 10);
  14. n) optionally carrying out a final spinning operation (if point m is executed);
  15. o) unloading the hanks from the support means 30 for the final drying of these hanks.


[0059] For ecological and economic purposes, it should be noted that the used dye baths obtained from dyeing of the individual batches can be recuperated in an appropriate container (not shown), and, subject to titration and topping up of the various components, reused. It will be appreciated that, with suitable adaptations and simplifications, said operative cycle can advantageously also be used with other classes of dyes, different from indigo. It should also be noted that all of the particular characteristics and the above-described technical, economic and ecological advantages of this new machine, with the exclusion of those which relate to dyeing only with indigo, are mostly also valid for dyeing of many fibres with other classes of dyes.

[0060] In practice, the dyeing machine 10 according to the present invention revolutionises the present system for dyeing of hanks in dyeing cabinets since, unlike these dyeing cabinets, it permits execution of the entire operative cycle in its interior, without moving material, with drastic reductions of the ratio between the weight of the yarn and the volume of dye bath, and reductions of energy consumption, labour, and operative times, chemical products, and above all water. All of this takes place rationally, simply, conveniently, and above all economically and environmentally sustainable. Compared with the dyeing cabinets according to the prior art, the dyeing machine 10 according to the present invention is structurally simplified, and although being more complete, convenient and rational, its economic cost is substantially lower.

[0061] The dyeing machine 10 according to the present invention is also characterized by particular operative versatility and flexibility, since, with the support frame 14 rotating, it can dye and treat also garments made of knitwear or of fabric, with all of the above advantages. These processing operations are increasingly in demand, since they can be carried out in short periods of time on untreated garments which are already ready in stock, so as to permit deliveries which are speedy, and consequently in line with the increasingly rapid variations of fashion.

[0062] It should be noted that, since the dyeing machine 10 according to the present invention is substantially constituted by an apparatus with a cylindrical form, whereas the dyeing cabinets according to the prior art have a parallelepiped form, it is advantageous, and has a much lower economic cost with reference to the structure of the further version which operates under static pressure, which is a necessary condition in order to be able to dye hanks and/or ready-made garments made of synthetic fibres, requiring dye baths with temperatures close to 120/130°C. In fact, since it is cylindrical, the dyeing machine 10 can be subjected to higher pressures than those which can be obtained within a dyeing cabinet with a parallelepiped form, and can thus reach the above temperatures (120/130°C), with far higher performance levels than the maximum of 108/110°C which can be reached in the dyeing cabinets, which are normally pressurised to 0.4 bar.

[0063] It has thus been shown that the machine for dyeing of hank yarns and/or ready-made garments according to the present invention achieves the objects previously set out, and in particular provides the following advantages:
  • single machine for dyeing of hanks under nitrogen, with indigo, on standard rods, and/or of ready-made garments;
  • ratio between the volume of the dye bath and the weight of the yarn 2/3 lower than that of the dyeing cabinets according to the prior art;
  • recovery and reuse of the dye bath with indigo;
  • direct execution, internally, of complete dyeing operative cycles;
  • ecological dyeing cycle, under nitrogen, with indigo and reduction dyes;
  • better diffusion and fixing of the dye on the fibre;
  • possibility of cooling and activation with ultrasound of the dye bath with indigo, in order to increase the already greater colour yield;
  • drastic reduction of the consumption of caustic soda and sodium hydrosulphite, with indigo and other reduction dyes;
  • reduction of energy consumption;
  • reduction of water consumption;
  • drastic reduction of sulphites and sulphates in the waste waters;
  • reduction of the dyeing times;
  • reduction of the production costs;
  • possibility of single-phase cycles with dye baths with a high concentration of indigo and a high temperature;
  • maximum operative flexibility;
  • possibility of dyeing with other classes of dye (in air) different from indigo;
  • possibility of dyeing simply, with a variable capacity;
  • possibility of carrying out the phases of pre- and post-treatment in the dyeing cabinets according to the prior art;
  • possibility of dyeing ready-made garments made of either knitwear or fabric;
  • possibility of operating under static pressure with baths at a temperature higher than 100°C.


[0064] The machine for dyeing of hank yarns and/or ready-made garments thus designed can in any case be subjected to numerous modifications and variants, all of which come within the same inventive concept; furthermore, all the details can be replaced by technically equivalent elements. In practice, any materials, forms and dimensions can be used depending on the technical requirements.

[0065] The scope of protection of the invention is therefore defined by the appended claims.


Claims

1. Dyeing machine (10) for dyeing hank yarns with dyes different from indigo, comprising:

- at least one dyeing apparatus (12) provided with:

- a casing (18) enclosing at least one dye compartment (20); and

- at least one hermetically sealed hatch (22), which is provided on said casing (18) and permits access to said dye compartment (20);

- at least one support frame (14), which is mounted such as to rotate within said dye compartment (20) and is designed to rotate, by means of at least one rotation pin (16), around a central axis of rotation (A) which is horizontal and passing via said rotation pin (16);

- at least one tank (44, 46), containing at least one dye bath (B);

- at least one hydraulic circuit (28), which is connected hydraulically to said at least one tank (44, 46) and to said dyeing apparatus (12) in order to supply said at least one dye bath (B) from said at least one tank (44, 46) to said dye compartment (20) and vice versa; and

- a plurality of support means (30) for the hank yarns, which means are mounted on said support frame (14) and are accessible via said hatch (22),

wherein both said casing (18) and said support frame (14) have a circular form in vertical transverse cross-section, i.e. a cross-section obtained along a plane orthogonal to said central axis of rotation (A), such that said casing (18) has a cylindrical frontal wall and that said dye compartment (20) has a cylindrical form, wherein said hatch (22) is provided on said cylindrical frontal wall, and wherein said support means (30) are disposed on said support frame (14) according to a configuration which is preferably circumferential with respect to said central axis of rotation (A) and are placed in the vicinity of the inner surface of said cylindrical frontal wall, the dyeing machine (10) being characterized in that each support frame (14) is delimited by a pair of circular lateral walls (36, 38), which are flat, opposite each other and disposed orthogonally with respect to said central axis of rotation (A), wherein each hatch (22) has a width, measured along said central axis of rotation (A), which is equal to the distance between the two lateral walls (36, 38) of each support frame (14), and wherein each of said support means (30) is constituted by a rack supporting a plurality of hank-carrier rods (40) for the dyeing of said hank yarns.
 
2. Dyeing machine (10) according to claim 1, characterized in that it comprises:

- a first tank (44) which operates in air, containing a dye bath (B) different from indigo; and

- a second tank (46) which operates in air and is connected hydraulically to said first tank (44) which operates in air.


 
3. Dyeing machine (10) according to claim 1 or 2, characterized in that it comprises at least one recirculation circuit (48) for the dye bath (B) contained in said dye compartment (20) with a cylindrical form.
 
4. Dyeing machine (10) according to any one of claims 1 to 3, characterized in that it comprises one or more cascade sprinkler devices (52), which are connected hydraulically to said dyeing apparatus (12) via said hydraulic circuit (28), and which are designed to sprinkle said dye bath (B) directly in said dye compartment (20) with a cylindrical form.
 
5. Dyeing machine (10) according to any one of claims 1 to 4, characterized in that said dyeing apparatus (12) and/or said at least one tank (44, 46) are provided with means (56) for thermal regulation of said dye bath (B).
 
6. Dyeing machine (10) according to any one of claims 1 to 5, characterized in that said dyeing apparatus (12) is provided with one or more ultrasound generators (60) to increase the colour rendering further.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description




Non-patent literature cited in the description