WO2016008575A1

WO2016008575A1 - Method and plant for the treatment of fabrics after digital printing

Info

Publication number: WO2016008575A1
Application number: PCT/EP2015/001412
Authority: WO
Inventors: Marco CORTIANA; Milena CORTIANIA
Original assignee: CIBITEX Srl
Current assignee: CIBITEX Srl
Priority date: 2014-07-15
Filing date: 2015-07-10
Publication date: 2016-01-21
Anticipated expiration: 2017-01-15

Abstract

The present invention relates to a method and a plant for the treatment of a fabric after a digital printing operation, wherein it is provided to carry out one or more steps not in-line, by interposing a layer of separation net between the turns of the fabric printed and wound in a reel.

Description

METHOD AND PLANT FOR THE TREATMENT OF FABRICS AFTER

DIGITAL PRINTING

TECHNICAL FIELD

The present invention relates to the field of methods and plants for the treatment (sometimes called as finishing) of fabrics after a digital printing process (mainly carried out by inkjet technologies).

The term "treatment" here means the group of operations intended for the functionalization of fabrics, particularly the group of steaming, washing and drying operations and other possible additional optional operations .

PRIOR ART

In the prior art the textile digital printing is known, a relatively recent technique, that allows the fabric (briefly) to be printed with colours and patterns by means of ink jets directed on the fabric or on a transfer paper then used for transferring the patterns onto the fabrics by applying heat, pressure or other physical/chemical process.

This technique, compared with the former one (rotary screen printing techniques are conventionally used) allows even relatively small fabric pieces to be subjected to coloration and/or decorative operations, without this being a limit (the conventional coloration is justified - as regards costs, time and difficulties only when high volumes of fabrics are treated) .

Details about the digital printing process are here omitted since they are known and not useful for understanding the invention; suffice it to note that the fabric passes into a digital printer (inkjet) where droplets of dyes are projected on the fabric such to recreate the desired pattern .

The viscosity, of the inks usually is low in order to avoid spreading of the edges due to the textile supports being capillary, and in order to allow the pattern to have a perfect sharpness.

Usually the fabric is prepared beforehand by a "padding" impregnation by means of thickeners or similar preparations .

Immediately downstream : of the digital printing operation, usually - in sequence - the following operations are .carried Out:

- steaming (or fixing)

- washing

- drying .

Steaming operation serves for fixing the color into the fabric, the washing operation serves for removing the unfixed dyestuff and .the . drying operation serves for drying the fabric before other final treatments (if any) . In the prior art the method and the plants used in combination with digital printers can be of two types. A first type provides that to a great extent the plants being used are the same industrial plants used downstream of the conventional printing processes, mainly situated in the industrial factories located in the few textile manufacturing locations ; plants that . are ^' improperly used with a low economic and energy efficiency for the treatment of medium/low digital printed amounts, or also analog-deriving apparatuses turned into the digital process .

A second and more recent type, even if less spread, known and applicable to a limited number of cases is a manufacturing system that allows in-line operations to be carried out: the reel of fabric to be processed is unwound upstream of the digital printer, it passes in the digital printer itself, then into the steamer and then in the washing machine and in the drying machine, which are in-line . To this end such machines are made as real rotary machines with rollers (driving and idler rollers) through which the (unwound) fabric piece passes in a continuous manner starting from the rpller upstream of the printer to the winding rpller downstream of the drying machine.

The US patent US2013232746 describes such sequence of operations, all carried out in-line; on the same .machine, which therefore is quite complex and cumbersome; moreover although such method allows medium-small pieces to be treated with more advantages than the conventional technique_/ however it has some room for improvement,. For example think of the printin of very small pieces of the fabric: the passage thereof in-line provides ah initial length and a final length of the piece (about equal to the linear development of the path followed by the fabric in the plant) to be provided that are production waste (they are not completely treated) or, as an alternative, the use of a waste fabric piece at the beginning o the fabric piece to be treated, necessary for starting the machine.:

In the case of quite long in-line plants and of very small lengths of fabric to be treated it may occur that: such waste is larger than the fabric to be treated, with unacceptable economic loss. Starting difficulties, time and costs of such plants often do not justify the fact of being employed for very small amounts of fabric. Still, it has to be noted that in such conventional plants the energy and raw material consumption is relatively high, resulting from the need of starting the plant before its operation; the consumption of electric energy and clear water are particularly high.

A further problem of the known plants is related to the fact that they often need highly skilled personnel, able to operate and accurately regulate the plant (for example think of the regulation of the tension force and of the feeding speed of the fabric in the plant) .

Moreover such machines, especially if arranged in-line, often take spaces quite wide and developed in a mainly longitudinal direction, that may also not be available in the working area of small arid medium digital printing centers or that oblige the layout of the area to be modified if they are introduced ex-novo into an existing industrial environment.

Another solution is shown in the European patent application EP1298243: after printing, a separation covering is wounded in a reel together with the printed web and they both together are subjected to a steaming action inside a steaming machine_/ where the reel in an horizontal position (its central axis is horizontal) . In the steaming machine the steam is injected through radial nozzles from the outside to the inside of . the reel .

Since separation material of EP1298243 is a sheet of paper or plastic then the steam must be injected by the radial nozzles at a predetermined pressure (higher than the ambient pressure) , in order to let the steam to reach also the inner windings of the reel.

This can cause, under certain circumstances, some damages to the outer windings of the reel, those ones that directly faces the nozzles and are therefore subjected to a direct hit of high pressure hot steam flow .

On the other hand, it is not possible to reduce the steam pressure, for the presence of the separation material in form of a paper or plastic sheet, which naturally obstacles the steam flow.

Another drawback of the solution shown in EP1298243 is that, due to the above reasons, in certain cases, the steaming operation does not allows to have an uniform treatment of all the windings.

Still another limit of this known solution is that the washing step is carried out by firstly unwinding the reel, then washing the web in an un-winded condition and at lastly rewinding the web in a reel; this is an inline process, whose washing machine needs great free space .

OBJECTS AND SUMMARY OF THE INVENTION

It is the object of the present invention to overcome the drawbacks of the prior art.

In particular, it is the object of the present invention to provide a method and a plant for the treatment of fabrics after digital printing, that is able to reduce fabric waste generated on rotary in-line plants.

Another object of the present invention is to provide a method^: and a plant for the treatment of fabrics after digital printing, that is able to limit the spaces necessary for the operations and to allow a greater versatility upon the installation of the plant, since digital printing workshops, due to their inherent availability, often are not installed in industrial environments, such as sheds but more often they are small workshops placed in relatively small buildings and/or in spaces zoned for commercial or mixed use.

Another object of the invention is to provide a method allowing resources to be saved, particularly clear water and electric energy.

Still another object of the invention is to provide a method and a relevant plant usable also by not particularly skilled personnel, such as for example the digital printing operator not coming from textile industry.

Still another object of the invention is to provide a method and a relevant plant in which the steaming operation does not risk to damage the fabric, while at the same time allows for an homogeneous fixing treatment in all the windings of the reel.

Still another object is to have a simplified plant, with less components, and therefore, a reduced overall cost. These and other objects of the present invention are achieved by a method and a plant according to the respective independent annexed claims.

Accordingly a first object of the invention is a method for the treatment of a fabric after a digital printing process, comprising the steps of:

a. winding the fabric together with a separation material in a first reel of fabric and separation material about a first roller, two turns of the fabric being spaced out by one turn of the interposed separation material b. subjecting the fabric together with the separation material to a steaming operation for fixing a digital printing ink onto the fabric said steaming operation being carried out in a static manner, without unwinding the first reel

c. unwinding the fabric and the separation net from the first reel

d. winding only the fabric in a second reel around a second roller

e. subjecting the fabric to a washing operation

f . subjecting the fabric to a drying operation , in which said separation material is a net, said steaming operation being performed by the passage of steam in the first reel, said passage comprising a radial passage of steam from the inside to the outside of the reel, said steaming operation occurring with the first reel in vertical position, by natural convection of the steam. A second object of the invention is a plant for the treatment of a fabric after a digital printing process, comprising :

- a fabric steaming machine for fixing a digital printing ink

- a fabric washing machine

- a fabric drying machine

- a winding machine for a fabric to be treated together with a separation net in a first reel

in which

said fabric steaming machine comprises an elongated case in which a reel can be housed, a steam source operatively connected with said case and a base supporting the case, the case being rotatable between a vertical working position and an horizontal position, said case having a steam input and a steam output substantially at opposite ends of the elongated case, in said operative condition said steam output being substantially above said steam input, so that in said operative condition the steam flows into said case in an upward natural convective motion.

A first idea at the base of the present invention is based on the fact of not carrying out the operations inline, thus avoiding the use of rotary in-line plants; according to the invention the various operations are carried out "in batch", namely not in-line.

This allows waste to be reduced, very small pieces of the fabric to be treated, encumbrance and complexity of conventional plants to be reduced, while contemporaneously allowing an operation not to be stopped if only one of the machines fails or is subjected to maintenance, with the further advantage of using the same plants even in presence of several digital printers in the division.

A drawback that the Applicant had to solve for implementing the idea just described is about the fact that upstream of the steaming step, the ink is not fixed to the fabric yet, resulting in that therefore it was not possible to wind the fabric on a reel, otherwise the unfixed ink would migrate between the turns of the wound fabric, thus deteriorating the quality.

The Applicant on the contrary has brilliantly overcome such condition by providing, immediately downstream of the printing, the fabric to be wound on a reel together with a separation net: this latter, during the winding of the fabric, is interposed between the turns thereof, keeping them separated and preventing the ink from migrating and allowing an improved steaming operation. The presence of the net, instead of the paper or plastic sheet of EP1298243 allows for a better steaming process, more uniform: since the net does not obstacles the steam flow, the pressure of the latter can be reduced, inside the steaming case, to values proximate to the ambient pressure, therefore avoiding the drawbacks of known art and allowing for more uniform results; this allows as well said steaming operation being executed with the first reel in vertical position, by natural convection of the steam from the lower part of the steaming case to the higher part.

The vertical position together with the natural convective motion of the steam allows for an enhanced contact time between the steam and the fabric, also thanks to the net/ in this case a true sort of "Chimney o Stack Effect" takes place inside the steaming machine.

Such motion, being due to the natural convection of the steam, is relatively slow and allows the steam to penetrate and reach the inner windings of the reel without the need of using steam injection nozzles and high pressures.

With such synergy of advantages, the method and plant of the present invention allows to have a better steaming operation, with optimal results.

The presence of the separation net between the turns of the fabric wound after the printing, especially when made in a high transpirable manner, allows the steaming operation to be facilitated: the separation net, by spacing the turns of the fabric, allows the steam to better permeate into the reel and the ink to be better fixed .

Thus, by using the separation net it is also possible to prevent the ink from migrating between one turn and another adjacent one, of the fabric once it is wound. The separation net is interposed between two adjacent turns of the wound fabric; the separation net piece preferably has at least the same length and width of the fabric piece.

Therefore the plant suitable for implementing the method just described comprises :

- a machine steaming the fabric for fixing a digital printing ink

- a machine washing the fabric

- a machine drying the fabric

- a machine winding a fabric to be treated together with a separation net in a first reel.

Further advantageous characteristics are the subject matter of the annexed claims, which are an integral part o the present description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below with reference to non-limiting examples, provided by way of example and not as a limitation in the annexed drawings. These drawings show different, aspects and embodiments of the invention and, where appropriate, reference numerals showing like structures, components , materials and/or elements in different figures are denoted by like reference numerals .

In the annexed figures :

Figure 1 is a general outline of a plant according : to the invention;

Figure 2 is a simplified section of the winding machine of the plant of figure 1;

Figure 3 is a simplified side view of the steaming machine of the plant of figure 1;

Figure 4 is a simplified section of the unwinding machine of the plant of figure 1;

Figure 5 is a simplified section of the drying machine of the plant of figure 1;

Figures 6 and 7 are two simplified sections of two variants of a drying machine of the plant of figure 1; Figures 8 and 9 are details of the winding and/or unwinding machine of figures 2 and 4;

Figure 10 is a section view of a fabric wound together with a separation net around a steaming roller;

Figures 11 and 12 are a steaming roller and a detail thereof respectively.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible of various modifications and alternative forms, some preferred embodiments are shown in the drawings and will be described here below in details.

It should be understood, however, that there is no intention to limit the invention to the specific embodiment disclosed, but, on the contrary, the intention of the invention is to cover all modifications, alternative forms and equivalents falling within the scope of the invention as defined in the claims.

The use of "for example", "etc", "or" indicate nonexclusive alternatives without limitation unless otherwise defined. The use of "including" means "including, but not limited to, " unless otherwise defined.

Terms as "vertical" and "horizontal", "upper" and "lower"

(with no other indications) have to be read with reference to the assembling (or operating) conditions and with reference to the standard terminology in use in common speech, where "vertical", means a direction substantially parallel to that of the vector of the force of gravity "g" and horizontal means a direction perpend cular thereto.

Before going into the description of the plant, ; it is useful to dwell upon the description of the method of the invention.

In order to better explain it is specified that the method is applied immediately downstream of a digital printing operation.

In such operation the fabric, usually wound in a reel around a roller, is fed to the digital printing machine. This latter, as the fabric is fed, colours it with the selected patterns by means of ink jets.

Immediately downstream of the digital printing machine, the fabric s subjected to the method of the invention. Thus, when leaving the printing machine, according to step a . of the method of the invention, the fabric T is wound together with the separation net RS around a first roller CI, called also as steaming roller.

In practice the fabric T and the separation net S are wound together on the same roller CI, such as shown in fig.10, such that each turn of the fabric of the reel is in contact with^'■ tw© turns of the separation net RS (or equally there are two turns of fabric T spaced out by one turn of the interposed separation net RS) and that, therefore, the fabric T is never in contact with itself .

This prevents the ink, still unfixed, from migrating, damaging the printing just performed.

Details about the winding machine will be disclosed below .

According to the invention, said steaming operation is performed by the passage of steam in the first reel, said passage comprising a radial passage of steam from the inside to the outside of the reel, said steaming operation occurring with the first reel in vertical position, by natural convection of the steam.

As regards the separation net, it is advantageously preferably made of a polyester yarn.

Preferably the separation net is fabric net, still more preferably made by polyester _: yarns .

Preferably the polyester yarn has a linear mass density from 40 to 60 Den (Deniers) preferably equal to 50 Den. Preferably the net is subjected to scouring and heat setting treatment.

Preferably the net has a product weight per m² ranging from 90 to 140 grams, in particular about equal to 100 ··/- 10 grams.

Preferably the net has a thickness ranging from 0.26 to 0.45 mm, preferably about equal to 0.36 mm -/- 0.02 mm. Preferably the net has holes, still more preferably square holes,; with a dimension (diameter for round holes or side for square holes) about rom 0.7 mm to 1.8 mm, preferably about equal to 1 mn and a pitch from 3 mm to 6 mm., preferably about equal to ^';^■¾ mm in both the two directions .

Preferably the arrangement of the holes, particularly of the square holes, is like a rhomb.

Preferably the net has a longitudinal ultimate tensile strength from 150 N to 230 N, preferably about equal to 190N and a transverse ultimate tensile strength from 450 N to 560 N, preferably about equal to 500N.

Such a net, comprising one or more of the previous characteristics, is particularly useful for obtaining - together - both a good separation of the layers of the wound fabric and an optimal passage of the steam with advantages for the efficiency of the fixing or steaming treatment .

Immediately after step a. step b. of the method is carried out that provides to subject the fabric to a steaming operation for fixing the digital printing ink onto the fabric.

Even if in principle it is possible to provide more than one separation net, the description below makes reference to the case when only one separation net RS is used, the simplest and most satisfactory case as regards practicality and results.

In the steaming operation (sometimes called also as fixing, in technical jargon) the fabric T and the separation net RS are subjected together to the action of steam, usually produced in the boiler at temperatures ranging from 98°C to 103°C and pressures ranging from 4 to 8 bar, preferably about equal to 5 or 6 bar.

in this operation the separation net RS, in addition to prevent ink from migrating, it also carries but another action particularly useful for the overall efficiency of the method.

It allows the steam to permeate within all the areas of the fabric, making it possible to make the fixing of the ink onto the fabric very homogeneous.

This is particularly important when considering that the steaming operation is not carried out with the fabric moving between the rollers, but with the fabric (and separation net) wound in the reel around the roller CI, in a static manner (or "motionless") in other words and without injecting the steam at high pressures, as in the known art.

To this end, preferably, the first roller CI, on which the fabric and the separation net are wound, has the side surfaces perforated and an axial cavity in communication with the holes of the side walls, such as shown in figs. 11 and 12.

In a preferred embodiment, the steaming machine comprises a case 31 in which the first reel is housed in a vertical position (with the central axis substantially in a vertical position) during the steaming operation : ; the operation condition is shown in fig. 3.

The steam source 32, such said boiler, provides a steam flow inside the case 31; said steam is supplied in the case 31 substantially with ah ambient pressure (dedicated pumps or compressors being avoided) .

Particularly, when the case in an operation vertical condition (first reel in vertical) the steam is supplied at a lower part of the case, through a steam input, and naturally (for natural convection motion) moves upwards until reaching the steam output . It can be said, in other words, that the case 31 of the steaming machine works as a simple flue (or a stack or chimney) , in which the steam -entering at the lower part of the case 31-, naturally flows upwards.

Inside the case 31 of the steaming machine the steam flow hits the fabric and. the separation net both in an axial and radial direction, by means of the holes present on the roller CI and of the axial cavity thereof that acts as a channel supplying the steam; preferably the roller CI has a diameter of about 60mm a wall thickness about equal to 1.5 mm with perforation with a diameter of the holes about equal to 3.5 mm and pitch of 10 mm in the two directions, the material is AISI 304 stainless steel .

The steam, produced in the boiler is supplied into the housing of the steaming machine at ah ambient pressure, without using pumps or compressor.

Then, according to the method of the invention, in steps c. and d. the fabric and the separation net are separated: in order to obtain this the first reel is unwound and only the fabric T is wound again on a second roller C2, in a second reel, this time made only of fabric.

Downstream of such steps the fabric reel is therefore sent to step e., namely the washing step.

In principle it may be possible to carry out a conventional washing, where the fabric passes into a rotary washing machine provided with washing reservoirs and rollers.

However a static (or "motionless") washing is preferably carried out in step e . To this end the second roller C2 has perforated side walls and an axial cavity in communication with the holes of the side walls, like the roller CI.

Thus it is possible to send a washing liquid inside the axial cavity and to discharge it radially through the reel of fabric, that due to its nature causes the washing liquid to pass therethrough, thus obtaining very advantageous results as regards homogeneity and efficiency of the washing treatment.

For example the washing liquid may be softened water (preferably with 1 French degree max) with or without the detergent, preferably with liquid soap.

After the washing operation the fabric is subjected to step f. of the method of the invention, that is a drying operation.

This latter, unlike the steaming and washing operations, is carried out with the fabric moving in a rotary machine .

The drying operation is carried out by means of heat supplied to the fabric in the form of radiation and/or conduction .

Such two mechanisms for transmitting the heat may be Used alternatively or preferably in combination with one another .

In this last case firstly the transmission by radiation and then the transmission by conduction are carried out. Contemporaneously with the drying operation (preferably in the same machine) it is possible to provide also additional treatments, such as for example a surface finishing treatment with felt calender or the like.

Since the method of the invention has been just disclosed the following description of the plant will be clearer, made with reference to the annexed figures.

With reference to figure 1, it shows a plant 1 according to the invention and a digital printing machine SD, typically placed upstream (with reference to the production cycle) of the plant 1.

In figure 1, due to space needs, the time sequence of the operations is outlined by an arrow ending in the bottom left part and ideally it continues in the right part, from the top to the bottom.

Generally the plant 1 for the treatment of the fabric according to the invention develops downstream of the digital printer SD and it comprises:

- a machine 2 winding a fabric to be treated together with a separation net in a first reel

-÷ a fabric steaming machine 3 for fixing a digital printing ink

- a fabric washing machine 5

- a fabric drying machine 6.

It has to be noted now that the several machines are here shown as ''stand-alone" .machines namely separated one from each other, as individual units; it is obvious that in other embodiments (not shown) such rr.ach.i nes are - equally - incorporated within a single larger: machine, that individually performs the several functions of the individual machines just listed and that therefore it is a subject matter of the invention too.

The plant 1 shown in fig.l comprises also a machine 4 for unwinding the first reel of fabric . and separation net and for winding again only the fabric into a second Such machine 4 is present since in the following washing machine 5 the fabric is washed in a static manner, that is wound on the roller on which it has been wound in the machine 4, without being Unwound therefrom.

In a different, simpler, embodiment the washing is carried out in a usual manner, therefore with a rotary machine, at the entrance thereof a station (like the machine 4) is placed wherein he fabric is unwound from the first reel and separated from the separation net, then for being sent to a washing Operation in the conventional rotary machine.

Advantageously in a particularly economic embodiment, the machine 2 and the machine 4 are actually the same machine, where the driving rollers and the driven rollers are only exchanged if winding or unwinding is desired to be carried out.

If details of the individual machines 2, 3, 4, 5 and 6 of the plant, are desired (and still remembering that they may be completely or partially integrated in more complex working stations that carry out the same functions , even if combined together) make reference to detailed figures 2, 3, 4 , 5, 6, 7, 8 and 9.

In particular, fig.2 shows a simplified view of the winding machine 2.

It . comprises a first shaft 21 on which a reel of fabric T is placed after the printing step and a second shaft 22 on which a reel of separation net RS is placed and a driving shaft 23 on which the first roller CI is fitted. The machine 2 then comprises idler rollers to which further reference is hot made,, it being possible to change their number and position depending on needs and they being within the knowledge of the person skilled in the art in the light of the teachings provided herein. In use, the fabric T is unwound from the reel and contemporaneously also the separation net RS is unwound from its reel.

Therefore these two are faced one with the other at their larger face, placed in contact and wound around the same roller CI, such that one turn of the fabric is side by side and adjacent to two turns of the separation net, such as shown in fig.10.

Therefore a turn of the fabric is never in contact with the remaining turns of the fabric, but only with the interposed turns of the separation net, thus preventing unfixed inks - actually - from migrating. It has to be noted, by the way, that the reel of fabric T is generated immediately downstream of the digital printing machine SD: the ink does not immediately migrate but it is necessary a certain time and a certain humidity for such migration to occur.

Thus it is possible to carry out a step before the method of the invention, that is to wind the printed fabric in a reel only of fabric T commonly installed in the digital printer SD, which then is supplied to the machine 2 in order to be unwound and wound with the separation net. As regards the roller CI on which the fabric and the separation net are Wound together, this is provided With an axial cavity and it is perforated at its side surface, such as described above and shown in figs. 11 and 12. With reference to figs. 8 and 9, they show a particularly advantageous and optional arrangement of the machine 2: it comprises a translatable support 27 mounted on a rack 28 for the shaft 23 and the shaft 21 intended to receive and move the roller CI and the roller on which only the fabric T is wound, such that pieces of fabric and net having different dimensions can be treated, mainly aiming at making the plants compatible with the different printing widths of the digital printers on the market nowadays and in the future.

Now with reference to fig. 3, it shows the steaming (or fixing) machine 3.

According to the invention said fabric steaming machine 3 comprises an elongated case 31 in which a reel can be housed, a steam source 32 operatively connected with said case 31 and a base 33 supporting the case 31.

The case 31 is rotatable between a vertical working position and a loading/unloading horizontal position, said case 31 has a steam input 38 and a steam output 39 substantially at opposite ends of the elongated case 31, in said operative condition said steam output 39 is substantially above said steam input 38 as shown in fig. 3, so that in said operative condition the steam flows into said case 31 in an upward natural convective motion between the input 38 and the output 39.

The steaming chamber or case 31 is the place where the first reel of fabric and separation net wound on CI is housed.

Then the machine 3 comprises a steam source 32 operatively connected to the case 31, in addition to - in the non-limiting shown embodiment - a base 33.

In order to facilitate the operation of the machine 3 and to reduce encumbrance, the case 31 is rotatable on the base 33 between a loading/unloading position, where it is horizontal and a working position (fig.3) where it is vertical.

The operation for inserting and removing the reel of fabric and separation net is carried out with the case 31 in horizontal position, while the steam treatment for fixing the inks occurs with the case in vertical position .

The case 31 preferably is cylindrical, with at least one loading unloading aperture placed at one of the bases of the cylinder.

The steam source 32 for example is a simple boiler with heating elements, but it may be possible to provide also more evolved embodiments or embodiments where the steam source is outside the machine 3, still being, at least conceptually, a part of it.

The steaming machine 3 comprises a case 31 in which the first reel is housed in a vertical position (with the central axis substantially in a vertical position) during the steaming operation; the operation condition is shown in fig. 3.

The steam source 32, such said boiler, provides a steam flow inside the case 31; said steam is supplied in the case 31 substantially at an ambient pressure (dedicated pumps or compressors being avoided) : to this extent, in preferred embodiments, the boiler and the case are directly connected simply by means of a piping and a valve .

Particularly, when the case in an operation vertical condition (first reel in vertical) the steam is supplied at a lower part of the case, through a steam input 39, and naturally (for natural convection motion) moves upwards until reaching the steam output 39. It can be said, in other words, that the case 31 of the steaming machine works as a simple flue, in which the steam -entering at the lower part of the case 31-, naturally flows upwards.

The steam is supplied also into the cavity of the first roller CI and it goes out therefrom in the radial direction through the holes of the side surface thereof, thus hitting the several layers (turns) of the fabric and separation net in a radial manner.

The action of the steam fixes the inks onto the fabric and the presence of the separation net allows the steam to be optimally spread, with advantages for the uniformity in treating the fabric.

Turning now to fig.4 it shows a simplified section of the unwinding machine 4.

It comprises a driven shaft 41 on which the first roller

CI is fitted with the reel of separation net and fabric.

The machine 4 then comprises two driving shafts 42, 43 intended to house a second roller C2 for the fabric and a third roller C3 for the separation net respectively

(it has to be noted that in very simplified embodiments this latter can be omitted) .

It has to be noted that the shafts of the machine 2 and 4 can also be very short intended to engage by friction the edge of the respective rollers, for example there being provided conical ends to allow rollers with different diameters to be engaged.

Then the machine 4 comprises one or more idler rollers to which further reference is not made due to reasons similar to those for the machine 2.

In use the first roller CI on which the first reel comprising fabric and separation net is wound is fitted on the driven shaft 41; the driving shafts 42 and 43 are operated thus allowing the fabric and the separation net to be separated.

The former is wound in a reel around a second roller C2, provided also with an axial cavity connected to holes on the side surface, likewise the roller CI.

In a particularly advantageous variant, the machine 2 is the same machine 4 with the driving rollers and the driven rollers which have been reversed.

Likewise, the machine 4 may be provided with the rack system described above and to which further reference is not made by brevity reasons.

With reference now to the washing machine 5, it is schematically shown in fig.5.

In its general aspects the machine 5 comprises a case 51 wherein the second reel of only fabric is housed, for example by fitting the second roller C2 on the shaft 52 of the machine 5.

The machine then comprises a washing fluid source 53, for example housed in the base of the machine 5, such as a fluid reservoir or the like and the hydraulic circuit intended to supply it, under pressure, in the cavity of the second roller, for example by means of the shaft 52 that to this end is provided also with supply nozzles or holes .

The washing fluid is preferably supplied radially, from the inside to the outside: the washing fluid thus passes through the turns of the fabric of the second reel, guaranteeing a uniform and efficient washing thereof. Also in this case, such as for the steaming, the machine

5 allows a "motionless" washing, namely obtained without unwinding the fabric reel; as well as it is possible to provide the roller C2 to be placed so as to rotate about its axis by driving the shaft 52, such to exert on the washing fluid already impregnated within the fabric, a centrifugal acceleration, to facilitate its passage into the fabric.

Downstream (after) of the machine 5, the plant 1 comprises a drying machine.

Such machine is shown herein in a main embodiment, the one of fig.6, denoted by reference 6 and in an alternative embodiment, the one of fig.7, denoted with the reference 6'.

The parts in common to the two machines are denoted by the same reference numbers in the two figs. 6 and 7, but they are disclosed, for the sake of brevity, only for the machine 6. Therefore with reference to this latter, from fig.6 it is noted that it is a machine of the rotary type, where the fabric is unwound at the beginning of the machine, it is subjected to the operations passing through the rollers thereof and it is wound again in a reel at the end.

In addition to the driven and driving rollers, pulling and tensioning rollers that may be provided in the machine 6 and that in general are within the knowledge of the person skilled in the art, it is interesting to dwell upon other arrangements that allow the fabric to be dried homogeneously and efficiently.

The machine 6 comprises a radiation drying device 63, that provide to heat the fabric.

Preferably such device 63 comprises one or more infrared ray lamps_/ that dry the fabric during its passage. In the preferred and shown embodiment there are two groups of opposite lamps, the fabric passing through such groups, such to dry it on both the sides.

Preferably dowhstream of the radiation drying device 63, there is provided a conduction drying device 64, that in the shown embodiment comprises a pair of heated rollers, for example with heating elements or the like, with which the fabric is put in contact, drying it.

Optionally the machine 6 then comprises a felt calender 65 for the surface treatment of the fabric.

Downstream of the conduction drying device 64 the fabric is wound on a final roller, for example made of paperboard or the .i ikc .

In the variant of fig.7 the machin 6' optionally comprises a reservoir 61 and a pair of opposite rollers

62 the fabric passing therethrough.

Such arrangement allows the machine 6' also to be used as a pre- reatment machine: in practice the fabric upstream of the printing is impregnated or covered by a "coating" particularly useful for facilitating the adhesion of the printing inks to the fabric and the accuracy when forming the pattern.

There are further provided the radiation drying device

63 and the conduction drying device 64, in sequence (in the direction of the passage of the fabric into the machine 6') ,

Thus the ob ects. listed above are achieved.

Obviously several variants to what described up to now are possible all to be considered as part of the present invention .

Claims

1) Method for the treatment of a fabric after a digital printing process, comprising the steps of:

c. unwinding the fabric and the separation net from the first reel

d. winding only the fabric in a second reel around a second roller

e. subjecting the fabric to a washing operation

f. subjecting the fabric to a drying operation

characterized in that:

said separation material is a net, said steaming operation being performed by the passage of steam in the first reel, said passage comprising a radial passage of steam from the inside to the outside of the reel, said steaming operation occurring with the first reel in vertical position, by natural convection of the steam.

2) Method according to claim 1, wherein the washing step e. is carried out in a static manner, with the fabric wound in the second reel, preferably by the passage of a washing fluid in the radial direction from the inside to the outside of said second reel.

3) Method according to claim 1 or 2, wherein immediately prior to step f . the fabric is unwound from the second reel, step f. being carried out with the fabric moving between the rollers of a rotary drying machine and wherein immediately after step f . the fabric is wound into a final reel around a final roller.

4) Method according to one or more of the preceding claims, wherein step f. provide to carry out the drying operation by a combined action of heat radiation and conduction .

5) Method according to the preceding claim, wherein the fabric radiation action comprises the step of using infrared lamps and the action transmitting heat to the fabric by conduction comprises the step of placing the fabric in contact with at least one hot body, preferably a heated roller.

6) Plant (1) for the treatment of a fabric after a digital printing process, comprising:

- a fabric steaming machine (3) for fixing a digital printing ink

- a fabric washing machine (5)

- a fabric drying machine (6, 6')

- a winding machine (2) for a fabric to be treated together with a separation net in a first reel

characterized in that

said fabric steaming machine (3) comprises an elongated case (31) in which a reel can be housed, a steam source (32) operatively connected with said case (31) and a base (33) supporting the case (31) , the case (31) being rotatable between a vertical working position and an horizontal position, said case (31) having a steam input (38) and a Steam output (38) substantially at opposite ends of the elongated case (31), in said operative condition said steam output (39) being substantially above said steam input (38), so that in said operative condition the steam flows into said case (31) in an upward natural convective motion.

7) Plant according to the preceding claim, further comprising a machine (4) for unwinding the first reel of fabric and separation net and winding again only the fabric into a second reel.

8) Plant according to claim 6 or 7, wherein, as an alternative or in combination:

the steaming machine (3) comprises:

- a steaming machine case (31) wherein said first reel of fabric and separation net is housed,

- a steam source (32) connected to the case (31) of the steaming machine for subjecting said first reel to an action of steam coming from said steam source (32);

the washing machine (5) comprises:

- a washing machine case (51) wherein said second reel of fabric is housed,

- a source of washing fluid (53) operatively connected to the washing machine case for subjecting said second reel to the action of the washing fluid

the drying machine (6,6 ') comprises at least one among:

- a radiation drying device (63)

- a conduction drying device (64), preferably placed in sequence the former with respect to the latter in the feeding direction of the fabric in the drying machine (6,6·) .

9) Plant according to one or more of claims 6 to 8, characterized in that it carries out the method according to one or more of the claims 1 to 5.