Apparatus and method for the wet heat treatment of continous textile substrates

Abstract

 A continuously operating apparatus (1) for the wet heat treatment of a continuous textile substrate (2) advancing in a predetermined direction is described, the apparatus (1) comprising: a unit (3) for hydro-thermal treatment of the textile substrate (2), comprising a chamber (32) able to contain a heated treatment fluid (35); a group (40) for conveying the textile substrate (2) into the hydro-thermal treatment unit (3); and a group (41) for conveying the textile substrate (2) out of the hydro-thermal treatment unit (3), characterized in that it also comprises pressure sealing groups (50,51), said pressure sealing groups being associated with said substrate conveying groups (40,41) so as to close said chamber (32) in a substantially sealed manner so that the treatment fluid (35) may be pressurized to a pressure higher than atmospheric pressure.

Description

[0001] The present invention relates to the textile sector and in particular concerns the wet treatment of continuous textile substrates. Even more particularly it concerns an apparatus and a method for the wet heat treatment of continuous textile substrates.

[0002] In the cycle for the processing of continuous textile substrates - in the case in question fabrics - between the unprocessed loom stage and the finished garment stage generally two quite different processing steps may be defined: a wet treatment step and a dry treatment step.

[0003] For example, with specific reference to wool fabrics or to fabrics containing mainly wool fibre, the basic sequence of the preparation operations may be: "washing - setting - dyeing" or "washing - setting - fulling - dyeing".

[0004] It is known that the fulling and dyeing operations, performed in a watery bath at fairly high temperatures, in the presence of chemical agents and subject to a vigorous mechanical action, cause more or less irreversible physical and mechanical distortions in the fabric if it has not been set beforehand.

[0005] Setting the fabric, or stabilizing its flat surface structure, essentially means subjecting it in a flat, extended and where applicable compressed form, to a hydro-thermal treatment which reaches a temperature albeit slightly higher than that at which the fabric will subsequently be fulled and/or dyed. Since the temperature of the watery bath for dyeing the wool fabrics is close to the boiling temperature, it follows that the hydro-thermal setting treatment must exceed at least 100°C.

[0006] The oldest wool setting technologies are based on discontinuous systems which generally envisage alternately unwinding and rewinding the fabric between two beams and immersing it in a hot watery bath; finally, the fabric is cooled by causing it pass through a cold watery bath and is gathered at the machine outlet. The temperature of the treatment bath varies from a minimum of 60-80°C to boiling point. In some cases reducing chemical products are added to the treatment bath, said products favouring and accelerating the setting reaction of the wool fibre. The most well known and sometimes still used techniques of this type are the more simple technique of "potting" and the more sophisticated technique of "crabbing".

[0007] Both these technologies are able to impart a degree of setting which is generally sufficient partly owing to the assistance of chemical products which favour the intermolecular reactions of the wool fibre. However, chemically assisted treatments are not devoid of risks because of the increased dyeing affinity of the fibre which results in non-uniform rising of the dye and consequently lack of homogeneity in the dyeing intensity and tone.

[0008] However, the most negative aspects are those associated with the very low productivity and high labour intensiveness.

[0009] A more modern version of crabbing is that of the continuous operation type, which differs from the former in terms of the actual setting technology.

[0010] A more recent and effective variant of continuous crabbing essentially envisages the use of a belt with a rigid and essentially non-yielding base structure having a surface which is made impermeable by spreading with silicone. These features allow specific pressures to be achieved on the surface of the drum and on the fabric which are very high such that the steam generated is able to reach pressures and temperatures which are considerably higher compared to atmospheric conditions. Consequently, the fabric is also heated to values much higher than the boiling temperature of water.

[0011] The more recent version of continuous crabbing, if on the one hand it solves satisfactorily the technological problem of the setting treatment in a pressurized environment, on the other hand poses a qualitative problem in terms of the fabric, which hitherto appears to be insurmountable. The composite structure of the novel pressing belt and its notable effectiveness in achieving the required pressurized conditions is in fact such as to cause irreversible damage to most of the articles which undergo treatment, so much so as to result in a decline in this technology.

[0012] An attempt has been made to design a wet setting machine which incorporates, with continuous operation, the original idea of treating the fabric in hot water, using a hydrostatic pressure superheating technique disclosed in the patent US-4,152,908. A heated metal drum rotates inside a tank which is practically totally immersed in hot water. The fabric to be set is fed so as to be wound around the surface of the drum and immersed in the setting bath which is heated, emerging from the tank at the end of its travel path so to be cooled with fresh water. A water column is created at the inlet and outlet openings of the tank and exerts a pressure on the setting bath equal to its hydrostatic thrust. Consequently, the setting bath is heated to a temperature equivalent to its pressure such that basically the fabric is treated in water at a temperature slightly greater than 100°C. A second version of the same machine envisages the incorporation, at the inlet and outlet openings of the tank, of a closing device with the function of a water vapour barrier, which extends from the underlying surface of the hot setting bath. Essentially, this device, consisting of a set of three rollers rotating in contact with each other, is intended to cause the vapour to exert a certain pressure on the surface of the setting bath. However, the cross-section of the opening is not totally closed by the device which leaves breather gaps communicating with the external environment.

[0013] The negative aspect of this solution is that the degree of superheating obtained is necessarily limited by the need to keep the dimensions of the hydrostatic column within certain limits and consequently the temperature of the setting bath is low. The dimensions of the machine also constitute a major limitation.

[0014] The main object of the present invention is that of providing an apparatus and a method for the wet heat treatment of a continuous textile substrate which solves the problems and overcomes the shortcomings of the known apparatus.

[0015] This object, together with others, is achieved by means of an apparatus according to Claim 1 and a method according to Claim 22. The dependent claims define further advantageous features of the invention. All the claims are understood as forming an integral part of the present description.

[0016] According to a first aspect, the present invention provides a continuously operating apparatus for the wet heat treatment of a continuous textile substrate advancing in a predetermined direction, the apparatus comprising: a unit for hydro-thermal treatment of the textile substrate, comprising a chamber able to contain a heated treatment fluid; a group for conveying the textile substrate into the hydro-thermal treatment unit; and a group for conveying the textile substrate out of the hydro-thermal treatment unit, characterized in that it also comprises pressure sealing groups, said pressure sealing groups being associated with said substrate conveying groups so as to close said chamber in a substantially sealed manner so that the treatment fluid may be pressurized to a pressure higher than atmospheric pressure.

[0017] Preferably each of said conveying groups comprises at least one motorized roller.

[0018] Preferably each of said pressure sealing groups comprises a substantially idle roller having a lateral surface with a lining of resilient material.

[0019] The apparatus preferably also comprises pressure transmission means which cooperate with the pressure sealing groups.

[0020] Preferably each of said pressure sealing groups comprises a longitudinal sealing element which engages at the bottom flush with the lateral surface of the at least one motorized roller.

[0021] Preferably each of said pressure sealing groups comprises first transverse sealing elements which engage transversely in a sealed manner with the lateral surface of the at least one motorized roller, at the respective ends.

[0022] Preferably each of the pressure sealing groups comprises second transverse sealing elements at least partially engaged flush with said first transverse elements of the motorized rollers.

[0023] Preferably the longitudinal sealing element comprises an inflatable tube over which a sliding block element made of anti-friction material is mounted.

[0024] Typically the longitudinal sealing element is substantially integral with pairs of end plates.

[0025] Preferably the first transverse sealing elements comprise sliding block elements which are substantially semicircular and made of anti-friction material and which are coupled with elastic thrusting elements.

[0026] Preferably the first transverse sealing elements are housed and supported in pairs of end plates.

[0027] Preferably the second transverse sealing elements comprise sliding block elements which are substantially circular and made of anti-friction material.

[0028] Typically the second transverse sealing elements are associated with end walls of the said idle roller and engaged flush with the pair of end plates.

[0029] Preferably a rotating - preferably heated - cylindrical drum is housed inside the chamber.

[0030] Preferably the chamber comprises a portion which houses a regulating roller for controlling the tension of the textile substrate.

[0031] Advantageously the regulating roller is operationally connected to the group for conveying the textile substrate into the unit.

[0032] Preferably the unit for hydro-thermal treatment of the textile substrate comprises a first circuit for supplying and pressurizing the treatment fluid inside said chamber.

[0033] Preferably the unit for hydro-thermal treatment of the textile substrate comprises a second circuit for heating the treatment fluid inside said chamber.

[0034] Advantageously the first supplying and pressurizing circuit and the second heating circuit are operationally connected to a management system.

[0035] Typically the treatment fluid is an essentially water-based fluid.

[0036] Advantageously relations between the temperature-dependent equilibrium pressure of the water and the pressure-dependent equilibrium temperature of the water have been entered into said management system so as to be able to define a predetermined set-point value "Pset" of the pressure and a predetermined set-point value "Tset" of the temperature so that the actual pressure "Pe" and the actual temperature "Te" of the treatment fluid are measured and compared with the respective set-point values "Pset" and "Tset" and if necessary the actual pressure and the actual temperature are corrected until the divergence between the values, i.e. "Pe" and "Pset" and "Te" and "Tset", respectively, falls within a predefined tolerance range.

[0037] According to a second aspect the present invention provides a method for the wet heat treatment of a continuous textile substrate advancing in a predetermined direction, the method comprising the steps of: conveying said textile substrate into a unit for hydro-thermal treatment of the textile substrate; hydro-thermally treating the textile substrate inside a chamber with a heated treatment fluid; and conveying said textile substrate out of the unit, characterized by the steps of closing in a substantially sealed manner said chamber by means of pressure sealing groups; and pressurizing the treatment fluid within the sealingly closed chamber to a pressure higher than atmospheric pressure.

[0038] The present invention will be described in detail in the detailed description which follows, provided purely by way of a non-limiting example, to be read with reference to the accompanying plates of illustrative drawings, in which:

• Fig. 1 shows a schematic, substantially cross-sectional view of an apparatus according to a first embodiment of the present invention;
• Fig. 2 shows a schematic, substantially enlarged cross-sectional view of the inlet section of the apparatus according to Fig. 1;
• Fig. 3 shows a schematic, substantially enlarged cross-sectional view of the outlet section of the apparatus according to Fig. 1;
• Fig. 4 shows a cross-section along the line A-A in Fig. 5;
• Fig. 5 shows a cross-section along the line B-B in Fig. 4;
• Fig. 6 shows a schematic, substantially enlarged cross-sectional view of the inlet section of an apparatus according to a second embodiment of the present invention; and
• Fig. 7 shows a schematic, substantially enlarged cross-sectional view of the outlet section of an apparatus according to a second embodiment of the present invention.

[0039] Fig. 1 shows an overall view of a first embodiment of a continuously operating apparatus 1 for the wet heat treatment of a continuous substrate 2 advancing in a predetermined direction. Typically, the continuous substrate is a fabric. The apparatus 1 comprises: a unit 3 for the hydro-thermal treatment of the fabric; a first group 40 for conveying the fabric into the treatment unit 3; a second group 41 for conveying the fabric out of the treatment unit 3; a section 6 for pre-impregnation of the fabric; and a section 7 for dehydration of the fabric. The apparatus 1 also comprises pressure sealing groups 50 and 51 associated with said fabric conveying groups 40, 41.

[0040] In greater detail, the unit 3 for hydro-thermal treatment of the fabric comprises a load-bearing structure 30, the inner wall 31 of which has an essentially cylindrical profile and defines an essentially cylindrically shaped chamber 32. The chamber 32 houses a cylindrical drum 33 which is preferably heated. Preferably the cylindrical drum 33 rotates about an axis 330 by means of a known motor means (not shown).

[0041] The cylindrical drum 33 is delimited by a lateral surface 331. The lateral surface 331 and the inner wall 31 of the load-bearing structure 30 define a first portion 320 of said chamber 32.

[0042] The inner wall 31 of the load-bearing structure 30 comprises an upper central part 310 and upper lateral parts 311 and 312 which define second chamber portions 321 and 322 for entry and exit of the fabric into/from the treatment unit 3. The inner wall 31 comprises a further part 313 which defines a third chamber portion 323. The third chamber portion contains members for controlling the tension of said fabric. The second portions 321 and 322 are open at the top and rotatably support internally rollers 332 and 333, respectively, for driving the fabric; the third chamber portion 323 rotatably supports internally a pair of re-directing rollers 334 and a roller 335 for regulating the tension of said fabric, arranged between them. Conveniently said regulating roller 335 is operationally connected to an electronic management system (known and not shown) of said apparatus.

[0043] Said hydro-thermal unit 3 also comprises a first circuit 34 for supplying and pressurizing a treatment fluid 35 and a second circuit 36 for heating the fluid 35.

[0044] The first circuit 34 essentially comprises a tank 340 containing the treatment fluid, a pump 341 for supplying and pressurizing the fluid inside the chamber 32, a suction pipe 342 for drawing fluid from the tank 340, a delivery pipe 343 leading to the third portion 323 of the chamber 32, and a pipe 344 for the return or outflow of the excess fluid from the chamber 32 to the tank 340. Conveniently, a pressure trasmitter 343a is incorporated along the delivery pipe 343. Moreover, a pipe 345 for supplementing said treatment fluid is connected to the tank 340 and incorporates a modulating valve 345a. Finally, a level measuring device 340a is arranged inside said tank 340: the pressure trasmitter 343a and the modulating valve 345a are operationally connected to an electronic management system (known and not shown) of said apparatus.

[0045] The second heating circuit 36 comprises a pump 360 for recirculating said treatment fluid, the delivery of which is associated with a heat exchanger 361 for heating the treatment fluid. The heat exchanger 361 is connected, on the delivery side, to a pipe 362 which communicates with the second portion 322 of the chamber 32. The pump 360 is also connected, on the intake side, to a pipe 363 which is connected to the delivery pipe 343 of the first circuit 34.

[0046] Conveniently, a temperature transmitter 362a is incorporated along the pipe 362. Moreover, the heat exchanger 361 has a supply pipe 364 for supplying a known heating fluid, for example steam, diathermic oil, etc. and a pipe 365 for discharging said heating fluid. A modulating valve 364a is incorporated along said supply pipe. Conveniently, the temperature transmitter 362a and the modulating valve 364a are operationally connected to an electronic management system (known and not shown) of said apparatus 1.

[0047] With reference to Fig. 2, the group 40 for conveying the incoming fabric 40 according to a first embodiment comprises a spreading roller 42, a pair of motorized rollers 400 associated with a motor means 402 and with transmission means 403 (shown schematically in Fig. 1).

[0048] Similarly, with reference to Fig. 3, the group for conveying the outgoing fabric according to a first embodiment comprises a spreading roller 43, a pair of motorized rollers 400 associated with a motor means 412 and with transmission means 413 (shown schematically in Fig. 1). Conveniently, all the motorized rollers 400 are arranged with their respective axes along a same horizontal plane. Moreover, the rollers of each pair are spaced from each other.

[0049] With reference to Figures 2, 4 and 5, the pressure sealing group 50 comprises an idle roller 500, the lateral surface 501 of which has a lining 501 a of known resilient material, for example, such as natural rubber, synthetic rubber or the like. The lateral surface 501 of the idle roller 500 is engaged longitudinally in contact with lateral surfaces 404 of the motorized rollers 400. Moreover, in the region of respective axial hubs 502, 502', the idle roller 500 is associated with pressure transmission means 503, 503' of the known type, for example pneumatic, hydraulic or oil-hydraulic means or the like.

[0050] With reference to Figures 4 and 5, the group 40 for conveying the incoming fabric (as well as the group 41 for conveying the outgoing fabric) and the sealing groups 50, 51 are associated by means of longitudinal and transverse sealing elements supported and housed in pairs of end plates 52, 52'.

[0051] The lateral surface 404 of the motorized rollers 400 is engaged at the bottom flush with longitudinal sealing elements 504. The sealing elements 504 are arranged parallel to each other and with respect to the axes of said motorized rollers. Finally they are integral with the pairs of plates 52 and 52'.

[0052] Moreover, the lateral surface 404 of the motorized rollers 400, at the respective ends, is at least partially engaged flush with first transverse sealing elements 506, 506' arranged perpendicularly with respect to said longitudinal sealing elements. The first transverse sealing elements are housed and fixed with respect to the pairs of plates 52, 52'.

[0053] The idle rollers 500, along the end sections 508, 508', are associated with respective second transverse sealing elements 509, 509'. The second transverse sealing elements 509, 509' are at least partially engaged flush with the first transverse sealing elements 506, 506' of the motorized rollers. They are also engaged flush with the pair of plates 52, 52'.

[0054] In the configuration shown in Fig. 1, the reciprocal coupling of the motorized rollers 400 with the idle roller 500, the engagement of the motorized rollers with the longitudinal sealing elements 504 and the first transverse sealing elements 506, 506', the engagement of the first transverse sealing elements 506, 506' of the motorized rollers 400 with the second transverse sealing elements 509, 509' of said idle roller and the engagement of said second transverse sealing elements 509, 509' with the pair of plates 52, 52' produces fourth chamber portions 321 a and 322a. In particular, a fourth portion 321 a (Fig. 2) communicating with the second portion 321 for entry of the fabric 2 into the treatment unit 3 and a fourth portion 322a (Fig. 3) of the chamber 32 communicating with said second portion 322 for exiting of the fabric 2 from the treatment unit 3 are created.

[0055] Each longitudinal sealing element 504 comprises a seat 520 which houses an inflatable tube 522 over which a sliding block element 524 made of anti-friction material is mounted. Each sliding block element is engaged longitudinally in a sealed manner flush with the lateral surface of the respective motorized roller owing to the thrust exerted by the inflatable tube. Each longitudinal sealing element is integral with the pair of plates 52, 52'.

[0056] The first transverse sealing elements 506, 506' comprise sliding block elements which are substantially semi-circular and made of anti-friction material 526 and coupled with elastic thrust elements 536. The first transverse sealing elements 506, 506' are housed and fixed at their respective ends to the pairs of plates 52, 52' and are engaged perpendicularly in a sealed manner flush with the longitudinal sealing elements 504. Finally they are at least partially engaged in a sealed manner flush with the ends of the lateral surfaces 404 of the motorized rollers.

[0057] The second transverse sealing elements 509, 509' comprise substantially circular sliding block elements made of anti-friction material. They are arranged on the end walls 508, 508' of the idle rollers between the axial hubs 502, 502' and the lined lateral surface 501 a and rotate together with the rollers 500. The second transverse sealing elements 509, 509' are engaged in contact with the end plates 52, 52' with which they form a flush seal.

[0058] Figures 6 and 7 show, respectively, a second embodiment of the inlet and outlet section of an apparatus according to the present invention. The same components or functionally equivalent parts have been indicated by the same reference numbers and a detailed description thereof is not repeated. In particular, all the transverse and longitudinal sealing systems are substantially as described with reference to the first embodiment.

[0059] In the inlet section (and outlet section) of the second embodiment, unlike the first embodiment, a single motorized roller 400 cooperating with the idle roller 500 is envisaged. Preferably the axes of the motorized rollers 400 of the inlet and outlet group are situated in the same horizontal plane. The axes of the idle rollers 500 of the inlet group and the outlet group are also situated in the same horizontal plane.

[0060] Returning to Fig. 1, the section 6 for pre-impregnation of the fabric 2 with the treatment fluid 35 conveniently comprises a tank 61 containing the treatment fluid, arranged at the inlet of the apparatus 1. The section 6 also comprises a pair of idle bottom re-directing rollers 62 and a pair of idle upper re-directing rollers 63. The idle rollers 62 and 63 are arranged inside said tank and are designed so that the fabric is able to travel around them.

[0061] Still with reference to Fig. 1, the section 7 for dehydration of the fabric 2 conveniently comprises a pair of motorized pressing rollers 72, a dancing roller 73 and a re-directing roller 74. The fabric, as shown in Fig. 1, travels around the re-directing roller 74, the dancing roller 73 and the pressing rollers 72. The pair of pressing rollers 72, the dancing roller 73 and the re-directing roller 74 are housed inside a tank 71 for collecting the treatment fluid 35 removed from the fabric and arranged substantially at the outlet of the apparatus 1.

[0062] When the apparatus 1 is activated, the chamber 32 of the hydro-thermal treatment unit 3 is filled with the treatment fluid 35 by means of activation of the circuit 34. The pump 341 removes the treatment fluid from the tank 340 and supplies it into the third portion 323 of the chamber 32 until the inlet portions 321 and 321 a and outlet portions 322, 322a of the treatment unit are filled. During this initial stage the pressure sealing groups 50 and 51 are not operationally activated with respect to the fabric conveying groups 40 and 41, i.e. the idle roller 500 is not pushed against the motorized rollers 400. For this reason the treatment fluid 35 flows outside of said inlet and outlet portions, is collected in the basin 44 and returns into the tank 340 via the breather pipe 344.

[0063] Subsequently the pressure sealing groups 50 and 51 are operationally activated with respect to the fabric conveying groups 40 and 41.

[0064] In particular, the idle rollers 500 are pressed longitudinally into contact with the motorized rollers 400 by the thrust of the respective pressure transmission means 503, 503'. Conveniently, the pressure transmission means 503, 503' comprise pneumatic pistons. Owing to these pressure transmission means, the resilient linings 501 a of the lateral surfaces 501 are compressed and squashed on top of the lateral surfaces 404 of the motorized rollers. Underneath said rollers the longitudinal sealing elements 504 are actuated by means of the respective sliding block elements 524 which are pressed in a sealed manner flush against the lateral surfaces 404 of the rollers 400. The sliding block elements receive an upwards thrust from the pressure exerted by the inflatable tubes 522. In this way a longitudinal seal is provided between the pressure sealing groups 50 and 51 and the fabric conveying groups 40 and 41.

[0065] The seal in the transverse direction between the pressure sealing groups and the fabric conveying groups is provided by means of the first transverse sealing elements 506, 506' associated with the ends of the lateral surfaces 404 of the motorized rollers 400 and the second transverse sealing elements 509, 509' situated on the end walls 508, 508' of the idle rollers 500.

[0066] In this way the chamber 32 with the respective entry portions 321, 321 a and exit portions 322, 322a of the conveying unit 3 is closed by the reciprocal sealed engagement between the fabric conveying groups 40 and 41, the respective pressure sealing groups 50 and 51 and the respective pairs of end plates 52, 52' associated with the longitudinal sealing elements 504 and the transverse sealing elements 506, 506' and 509, 509'. Consequently the treatment fluid 35 ceases to flow outside of said inlet and outlet portions thus being able to assume a pressure higher than atmospheric pressure.

[0067] The circuits 34 and 36 are activated so as to keep the treatment fluid at predetermined pressure and temperature values, respectively. The pressure and temperature values of the treatment fluid are thus established inside the chamber 32 of the treatment unit 3 and in its portions 320, 323, 321, 321 a, 322, 322a.

[0068] In order to predefine a certain pressure and temperature value of the treatment fluid, for example, water, the relations between the temperature-dependent equilibrium pressure of the water and the pressure-dependent equilibrium temperature of the water have been entered into the electronic management system (not shown). This allows a predetermined set-point value "Pset" of the pressure and a predetermined set-point value "Tset" of the temperature to be defined so that the actual pressure "Pe" and actual temperature "Te" of the treatment fluid are measured and compared with the respective set point values "Pset" and "Tset". Optionally the actual pressure and the actual temperature are corrected until the divergence between the values, i.e. "Pe" and "Pset" and "Te" and "Tset", respectively, falls within a predefined tolerance range.

[0069] In operational terms, the circuit 34 supplying and pressurizing the treatment fluid measures the actual pressure of the treatment fluid by means of the pressure transmitter 343a which sends the value "Pe" thereof to the management system; the latter compares it with the set-point value "Pset" and if necessary adjusts a variable command for the flowrate of the pump 341 until the divergence between the values "Pe" and "Pset" falls within the predefined tolerance range.

[0070] In the meantime, the circuit 36 for heating the treatment fluid draws part of the treatment fluid from the circuit 34, by means of the pump 360, so as to circulate it through the heat exchanger 361 and reintroduce it into the chamber 32 in the region of the outlet portions 322, 322a of the hydro-thermal treatment unit 3. The temperature transmitter 362a detects the actual temperature "Te" of the fluid and transmits the value thereof to the management system. The latter compares it with the set-point value "Tset" and if necessary adjusts the flowrate of the modulating valve 364a supplying the heating fluid, for example steam, into the heat exchanger until the divergence between the values of "Te" and "Tset" falls within the predefined tolerance range.

[0071] The treatment fluid, for example water, is set and kept by the circuit 34 at a prechosen pressure higher than atmospheric pressure and is set and kept by the circuit 36 at a prechosen temperature higher than the boiling temperature at atmospheric pressure, but not necessarily equal to that corresponding to the value of its pressure.

[0072] For this purpose, the maximum operative range of the pressure values varies from 0 to 3.0 bar, but preferably operation is performed at values ranging between 0.5 and 2.5 bar and advantageously between 1.0 and 2.0 bar.

[0073] The maximum temperature values are provided by the electronic management system on the basis of processing of the relation between pressure and temperature of the water in the state of equilibrium between the liquid phase and the vapour phase. For example, in the case of operative pressure values between 0.5 and 2.5 bar, said maximum temperature values vary in a range of between 111°C and 138°C.

[0074] However, it is preferable to reduce the operative temperature values with respect to said maximum values of a certain tolerance and safety margin, for example in the range of between 105°C and 130°C, so as not to give rise accidentally to vaporization of the treatment fluid.

[0075] The cylinder 33, which is completely immersed in the treatment fluid, is also heated, preferably by means of the introduction of steam internally. The relatively small volume of the portion 320, through which the fabric passes, transported on the lateral surface 331 of the cylinder, allows a consistent reduction in the volume of treatment fluid, thus reducing the heating times and ensuring more precise maintenance of the temperature conditions.

[0076] The continuous fabric 2 is made to advance in the direction of the arrow A so as to enter the apparatus 1 and is introduced into the preimpregnation section 6, being immersed in the treatment bath 35 inside the tank 61, being assisted therein by the pairs of idle bottom re-directing rollers 62 and idle upper re-directing rollers 63. The spreading roller 42 favours the subsequent engagement of the fabric with the conveying group 40 and with the pressure sealing group 50 and, in particular, with the motorized roller 400 and with the idle roller 500, respectively. The fabric is thus arranged between the lateral surface 404 of the motorized roller and the lining 501 a of the lateral surface 501 of the idle roller, coupling together of said rollers causing the fabric to advance inside the hydro-thermal treatment unit 3 and in particular the chamber 32.

[0077] Passing through the inlet portions 321 a and 321, the fabric travels over the re-directing roller 322 and rests on the lateral surface 331 of the rotating and heated cylinder 33 which starts to convey it through the portion 320 of said chamber until it is separated therefrom by means of the re-directing roller 333 and enters the outlet portions 322 and 322a. Along said path, the re-directing rollers 334 deviate the fabric into the third portion 323. Inside the third portion 323, the fabric undergoes control of the longitudinal tension by means of the tension regulating roller 335.

[0078] The fabric engages with the conveying group 41 and with the pressure sealing group 51 in a manner entirely similar to that of the corresponding groups 40 and 50, emerging from the hydro-thermal treatment unit 3 and entering the dehydration section 7. The spreading roller 43 and the re-directing roller 74 direct it towards the dancing roller 73 and the pair of pressing rollers 72 which remove the excess quantity of treatment fluid from the fabric. The excess fluid is collected in the tank 71 and the fabric finally emerges from the apparatus 1 in the direction of the arrow B.

[0079] Conveying of the fabric inside the hydro-thermal treatment unit 3, and hence the chamber 32, is performed by the action of the conveying groups 40 and 41 which are engaged in contact with the pressure sealing groups 50 and 51, assisted by the cylinder 33 arranged between them and synchronized by the roller 335 for regulating the tension of the fabric.

[0080] The motorized rollers (or individual roller) 400 of the conveying group 40 are made to rotate by the motor means 402 with which said rollers are associated by means of the known transmission means 403, for example of the belt and pulley type. In this way the roller 500 of the pressure sealing group 50 is also made to rotate as a result of the respective contact engagement. Similarly, the rollers (or individual roller) 400 of the conveying group 41 are made to rotate by the motor means 412 with which said rollers are associated by means of the known transmission means 413, for example of the pulley and belt type. In this way the roller 500 of the pressure sealing group 51 is also made to rotate as a result of the respective contact engagement.

[0081] The prechosen speed of advancing movement of the fabric 2 is regulated by adjusting the motor means 412, downstream of the chamber 32, so that the speed of rotation of the motorized rollers of the group 41 is substantially constant and substantially equal to that of the motorized rollers of the group 40. However, the fabric could be subject to positive or negative longitudinal tensile stresses along its travel path inside the chamber 32. The tension regulating roller 335 detects the magnitude of these tensile stresses, transmits it to the electronic management system which compares it with a preset set-point value of the tension. If necessary, the electronic system causes the motor means 402, upstream of the chamber 42, to perform a variation in the speed of rotation of the rollers 400 in order to cancel out said longitudinal tensile stresses. The cylinder 33 is made to rotate by a known motor means associated with an axial hub 330 thereof. Preferably, the motor means which rotates the cylinder 33 is electronically connected to the motor means 412 so that the linear speed of said cylinder follows and is substantially equal to the linear speed of the rollers 400 of the group 41.

[0082] During its travel path through the hydro-thermal treatment unit 3, the fabric is immersed in the treatment fluid, for example water, which completely fills the chamber 32, being prevented from escaping from the portions 321 a and 322a owing to the operative activation of the pressure sealing groups 50 and 51 with respect to the fabric conveying groups 40 and 41 by means of the respective engagement with the pair of end plates 52, 52' and actuation of the respective longitudinal and transverse sealing elements. However, the mechanical sealing action of the sealing elements is not hermetic also owing to possible wear factors, such that gradual infiltration and losses of the treatment fluid from the portions 321 a and 322a may occur. The circuit 34 performs the function of replenishing inside the chamber 32, by means of the portion 323, the loss of fluid escaping from the pressure sealing groups 50 and 51 and collected in the basin 44 from where the breather pipe 344 causes it to flow out to the tank 340. From the latter the fluid may be again reintroduced into the cycle by means of the pump 341. Moreover, a source of consumption of the treatment fluid is that resulting from its partial absorption by the fabric 2 leaving the hydro-thermal treatment unit 3. This quantity of treatment fluid is automatically replenished inside the chamber 2 by the pump 341 which draws from the reserve contained in the tank 340. Upon a consequent reduction in the volume of fluid inside the tank 340, the level measuring device 340a replenishes the reserve of the tank, interacting with the management system which, in tum, causes opening of the modulating valve 345a supplying fresh fluid.

[0083] The hydro-thermal treatment of the fabric, in particular of a wool fabric or a fabric partly containing wool fibre, is essentially aimed at performing a setting treatment.

[0084] It is known that setting of the wool may be performed with two levels of intensity which depend, according to the known glass transition curves, on the temperature to which the fibre is subjected depending on its moisture content.

[0085] It is thus possible to distinguish between cohesive set, which is weak and can be easily eliminated, and permanent set which is strong and withstands subsequent more intense wet treatment.

[0086] For the purposes of the wool fabric dyeing operation, which is performed in a watery bath and at atmospheric pressure, and hence at a temperature of less than 100°C, the requirement is that of setting the fabric beforehand using a higher temperature treatment which protects the fabric from mechanical folding deformation and from swelling of the surface.

[0087] The hydro-thermal treatment performed with the apparatus according to the present invention, at temperatures much higher than the boiling temperature of water, owing to the pressurized conditions of the bath, allows a substantially permanent level of setting of the wool fibre and fabric to be achieved.

[0088] The apparatus according to the present invention, by means of a technology based essentially on a hydraulic pressurization technique, ensures optimum conditions during the chemical-physical process of setting of the textile fibres.

[0089] By means of the present invention a continuous cycle process is provided, with the possibility of significantly high working speeds and therefore greater productivity and management of the plant even by only one operator.

[0090] The pressurization of the setting fluid achieved by means of the present invention is able to ensure predefined hydro-thermal conditions which are variable within a certain range so that they may be adapted to the required level of setting.

[0091] Conveniently, the apparatus according to the present invention does not requires pressing belts so that the risk of damaging the fabrics is eliminated.

Claims

1. Continuously operating apparatus (1) for the wet heat treatment of a continuous textile substrate (2) advancing in a predetermined direction (A-B), the apparatus (1) comprising:

- a unit (3) for hydro-thermal treatment of the textile substrate (2), comprising a chamber (32) able to contain a heated treatment fluid (35);

- a group (40) for conveying the textile substrate (2) into the hydro-thermal treatment unit (3); and

- a group (41) for conveying the textile substrate (2) out of the hydro-thermal treatment unit (3),

characterized in that it also comprises pressure sealing groups (50, 51), said pressure sealing groups being associated with said substrate conveying groups (40, 41) so as to close said chamber (32) in a substantially sealed manner so that the treatment fluid may be pressurized to a pressure higher than atmospheric pressure.

2. Apparatus (1) according to Claim 1, characterized in that each of said conveying groups (40, 41) comprises at least one motorized roller (400).

3. Apparatus (1) according to Claim 1 or 2, characterized in that each of said pressure sealing groups (50, 51) comprises a substantially idle roller (500) having a lateral surface (501) with a lining (501 a) of resilient material.

4. Apparatus (1) according to Claim 1, 2 or 3, characterized in that it also comprises pressure transmission means (503, 503'), said pressure transmission means (503, 503') cooperating with said pressure sealing groups (50, 51).

5. Apparatus (1) according to any one of Claims 2-4, characterized in that each of said pressure sealing groups (50, 51) comprises a longitudinal sealing element (504) which engages at the bottom flush with the lateral surface (404) of the at least one motorized roller (400).

6. Apparatus (1) according to any one of the preceding claims, characterized in that each of said pressure sealing groups (50, 51) comprises first transverse sealing elements (506, 506') which engage transversely in a sealed manner with the lateral surface (404) of the at least one motorized roller (400), at the respective ends.

7. Apparatus (1) according to Claim 6, characterized in that each of said pressure sealing groups (50, 51) comprises second transverse sealing elements (509, 509') at least partially engaged flush with said first transverse sealing elements (506, 506') of the motorized rollers.

8. Apparatus (1) according to any one of Claims 5-7, characterized in that said longitudinal sealing element (504) comprises an inflatable tube (522) over which a sliding block element (524) made of anti-friction material is mounted.

9. Apparatus (1) according to any one of Claims 5-8, characterized in that said longitudinal sealing element (504) is substantially integral with pairs of end plates (52, 52').

10. Apparatus (1) according to any one of Claims 6-9, characterized in that said first transverse sealing elements (506, 506') comprise sliding block elements (526) which are substantially semicircular and made of anti-friction material and which are coupled with elastic thrusting elements (536).

11. Apparatus (1) according to any one of Claims 6-10, characterized in that said first transverse sealing elements (506, 506') are housed and supported in pairs of end plates (52, 52').

12. Apparatus (1) according to any one of Claims 7-11, characterized in that said second transverse sealing elements (509, 509') comprise sliding block elements which are substantially circular and made of anti-friction material.

13. Apparatus according to any one of Claims 7-12, characterized in that said second transverse sealing elements (509, 509') are associated with end walls of the said idle roller (500) and engaged flush with the pair of end plates (52, 52').

14. Apparatus (1) according to any one of the preceding claims, characterized in that a rotating - preferably heated - cylindrical drum (33) is housed inside said chamber (32).

15. Apparatus (1) according to any one of the preceding claims, characterized in that said chamber (32) comprises a portion (323) which houses a regulating roller (335) for controlling the tension of said textile substrate (2).

16. Apparatus (1) according to Claim 15, characterized in that said regulating roller (335) is operationally connected to said group (40) for conveying the textile substrate into the unit (3).

17. Apparatus (1) according to any one of the preceding claims, characterized in that said unit (3) for hydro-thermal treatment of the textile substrate (2) comprises a first circuit (34) for supplying and pressurizing the treatment fluid (35) inside said chamber (32).

18. Apparatus (1) according to any one of the preceding claims, characterized in that said unit (3) for hydro-thermal treatment of the textile substrate (2) comprises a second circuit (36) for heating the treatment fluid (35) inside said chamber (32).

19. Apparatus (1) according to any one of Claims 17-18, characterized in that said first supplying and pressurizing circuit (34) and said second heating circuit (35) are operationally connected to a management system.

20. Apparatus (1) according to Claim 19, characterized in that said treatment fluid is an essentially water-based fluid.

21. Apparatus (1) according to Claim 20, characterized in that relations between the temperature-dependent equilibrium pressure of the water and the pressure-dependent equilibrium temperature of the water have been entered into said management system so as to be able to define a predetermined set-point value "Pset" of the pressure and a predetermined set-point value "Tset" of the temperature so that the actual pressure "Pe" and the actual temperature "Te" of the treatment fluid are measured and compared with the respective set-point values "Pset" and "Tset" and if necessary the actual pressure and the actual temperature are corrected until the divergence between the values, i.e. "Pe" and "Pset" and "Te" and "Tset", respectively, falls within a predefined tolerance range.

22. Method for the wet heat treatment of a continuous textile substrate (2) advancing in a predetermined direction (A-B), the method comprising the steps of:

- conveying (40) said textile substrate (2) into a unit (3) for hydro-thermal treatment of the textile substrate;

- hydro-thermally treating the textile substrate inside a chamber (32) with a heated treatment fluid (35); and

- conveying (41) said textile substrate (2) out of the unit (3), characterized by the steps of:

- closing said chamber (32) in a substantially sealed manner by means of pressure sealing groups (50, 51); and

- pressurizing the treatment fluid within the sealingly closed chamber (32) to a pressure higher than atmospheric pressure.

23. Method according to Claim 22, characterized by the step of bringing said treatment fluid (35) to a prechosen temperature, said temperature being higher than the boiling temperature at atmospheric pressure.

24. Method according to Claim 22 or 23, characterized in that the step of pressurizing the treatment fluid inside the chamber (32) comprises the step of pressurizing the treatment fluid to a pressure of between about 0 and 3.0 bar, preferably between about 0.5 and 2.5 bar and even more preferably between 1.0 and 2.0 bar.

25. Method according to any one of Claims 22-24, characterized in that the step of hydro-thermally treating the textile substrate inside a chamber (32) with a heated treatment fluid (35) comprises the step of filling said chamber (32) completely with treatment fluid (35).

Drawing