[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 19
th 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:
- 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;
- 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;
- 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;
- 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;
- 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;
- 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;
- 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;
- h) optionally repeating the operations c), d), e), f), g);
- i) spinning the hanks for a predefined period of time, with recovery of the extracted
dye bath B in the second, auxiliary tank 26;
- j) isolating the dye compartment 20 from the hydraulic circuit 28 for supply/regulation
of the nitrogen N;
- k) rendering the dye compartment 20 non-inert;
- 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;
- 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);
- n) optionally carrying out a final spinning operation (if point m is executed);
- 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.