EP0014787B1

EP0014787B1 - Method of, and apparatus for, reducing the liquid content of air-permeable material in tubular form

Info

Publication number: EP0014787B1
Application number: EP19790300253
Authority: EP
Inventors: Akos Laszlo; Horace Bartlett Merriman
Original assignee: Courtaulds PLC
Current assignee: Akzo Nobel UK PLC
Priority date: 1979-02-20
Filing date: 1979-02-20
Publication date: 1984-01-25
Also published as: EP0014787A1; DE2966566D1

Description

This invention relates to a method of, and apparatus for, reducing the liquid content of air-permeable material in tubular form, especially for reducing the moisture content of tubular fabric.
It is frequently necessary in the textile industry to remove liquid from tubular fabric, for example fabric which has been treated in a dyebath or subjected to bleaching or finishing treatments in liquid baths.
It is known to remove liquid from tubular fabric by passing the fabric through an apparatus comprising squeeze rollers, for example a mangle, in order to express a considerable part of the liquid therefrom. However, after such a liquid removal process, the fabric may still contain liquid in an amount of up to 60 per cent by weight of the dry weight of the fabric. In known liquid removal apparatus of this kind it is possible to pass the tubular fabric through the apparatus at speeds of up to 25 m/min.
Various methods are known for effecting a more complete drying of tubular fabric. One such method involves the use of hot air drying. The partially dried fabric, previously passed for instance through a mangle, is led over a stretcher for width regulation and then passes into a drying chamber where hot air is blown around and penetrates into the fabric. During the drying process, the tubular fabric fills with a mixture of hot air and vapour which flows in the direction opposite to that of the progression of the fabric, so that the fabric approaches the stretcher as a fully blown up tube. Practical operating speeds vary according to the type of fabric and other conditions, but under the most favourable conditions the speed of progression of the fabric through the drying chamber is not likely to exceed 15 m/min. If, therefore, such a drying chamber is employed to reduce still further the liquid content of tubular fabric which has been passed through squeeze rollers, the latter will not be used to their full capacity in a continuous process. Alternatively, the partially dried fabric coming from a number of squeeze rollers can be delivered to a greater number of drying chambers, but this means that the entire drying process becomes a batch process instead of a continuous process.
A further previously proposed apparatus for drying tubular fabric is described in U.S. Patent No. 1 745 499 in which the tubular fabric is passed up the inside of a tubular member with a perforated wall and is constrained to pass in contact with the wall by means of circular members located within the tubular fabric. The circular members have bevelled edges to fit against corresponding tapered surfaces of the tubular member of the apparatus. Three circular members are present, the upper and lower circular members being imperforate and the central circular member being perforated so that air blown into the tubular fabric through the perforated wall of the tubular member is constrained to pass through the central perforated circular member and must then pass out of the tubular fabric through the wall of the tubular member since its further passage along the inside of the tubular fabric is blocked by an imperforate circular member. A serious disadvantage of this known apparatus is that the close contact of the tubular fabric with the tubular member and the inner circular members is a pressure contact restricting movement of the tubular fabric through the apparatus and placing undue tension on the fabric as it is dragged through the apparatus.
The nature of the apparatus is such that it can cope with only a single diameter of tubular fabric and cannot be made adjustable to accept the wide range of sizes which must be processed in a modern textile factory.
The present invention provides an apparatus which can be adjusted in size to deal with tubular fabrics in a wide range of sizes. In apparatus according to the invention, the required air flows can be obtained without undue frictional restraint on the fabric in its passage through the apparatus.
For reducing the liquid content of open widths of fabric, it is known to apply suction to a surface of the fabric. One known apparatus employing this principle comprises a suction tube having a diameter of for instance 100 mm which is connected to a source of vacuum and has a longitudinal slit of a width for instance of 3 mm. The fabric is guided partially around the suction tube, over the slit, with the tube disposed perpendicular to the direction of advance of the fabric. The time during which the fabric is exposed to the influence of suction is very short, and it is therefore necessary to employ a high degree of vacuum at the slit to achieve any worthwhile extraction of liquid, for example a vacuum of up to 500 mm of Hg. Such a high vacuum has the effect of partially drawing the fabric into the slit. This causes a considerable increase of the longitudinal tension in the fabric, causing a lengthwise stretching of the fabric and restricting the employment of the method to comparatively insensitive kinds of fabric.
To the knowledge of the present inventors, there is no industrially used process for the suction extraction of liquid from tubular fabric. It would not be impossible to suction extract liquid from flattened tubular fabric employing the longitudinally slit vacuum tube used with open width fabrics, but this would lead to the serious disadvantage of a difference in the extraction from the layer of the flattened fabric tube in direct contact with the suction slit and the other layer of the fabric which cannot be in direct contact with the suction slit.
According to one aspect of the present invention, a method of reducing the liquid content of air-permeable material in tubular form, especially for reducing the moisture content of tubular fabric, by moving the tubular material longitudinally through means for applying suction to the external surface of the tubular material, is characterised in that said means for applying suction to the external surface of the tubular material are adjusted in size so that an internal surface of the means is in contact with inflated tubular material passing through it, inflation of the tubular material being caused by gas introduced into the tubular material, and then exhausted from it through apertures in said internal surfaces of the suction-applying means.
Advantageously, the tubular material is moved from a source through drying apparatus in a straight-line, or substantially straight-line, path and past said surface in a direction parallel to said surface, the drying apparatus further including a chamber, downstream in relation to the direction of tubular material movement, from said suction-applying means and pressurised to create a gas current into said tubular material; and nip-creating means downstream of said chamber preventing gas current flow in the downstream direction from said chamber, whereby drying can be effected at rates of tubular material movement comparable with the rate of movement through squeeze rollers.
According to a further aspect of the invention, apparatus for reducing the liquid content of air-permeable material in tubular form, especially for reducing the moisture content of tubular fabric, said apparatus comprising means for applying suction to the external surface of the tubular material, is characterised in that said means comprises hollow members defining a frame to surround said tubular material and present an inwardly-facing surface thereto adjustable in circumference to become identical in size with the outside circumference of different sizes of tubular material, said surface being formed with apertures communicating with the interior of the hollow members, and in that the apparatus further comprises means for advancing tubular material through the frame to move the external surface of the tubular material past said inwardly-facing apertured surface, and means for inflating the tubular material by introducing gas into it to maintain it in open form and close against said surface, whereby suction applied to the interior of the hollow members will create a gas current from within, and substantially only from within, the tubular material through the said apertures into the hollow members.
Advantageously, the apparatus is characterised by the provision of a straight-line, or substantially straight-line, path for tubular material through the apparatus and a chamber, downstream of said suction-applying means, in relation to the direction of tubular material movement, means for pressurising said chamber to create a gas current into tubular material within it and nip-creating means downstream of said chamber preventing gas flow within the tubular material in the downstream direction from said chamber.
The suction-applying means may be arranged to apply suction to the external surface of the tubular material in a single circumferential zone. Alternatively, the suction may be applied to a plurality of zones of the external surface of the tubular material, at least one of which zones is displaced from the other zone or zones in the direction of advance of the tubular material through the suction-applying means.
In a preferred embodiment of the apparatus according to the invention, each of the apertures in the or each hollow member is in the form of a substantially straight, elongate slot having a length considerably greater than its width and disposed with its axis inclined slightly to the direction of advance of the tubular material through the apparatus. For example, each slot may have a width of from 3 to 4 mm and a length of up to 100 mm, and the slot axis may be inclined at an angle of from 5 to 10 degrees to the direction of advance of the tubular material through the apparatus. By providing a large number of such slots in close side-by-side relationship, the tubular material is subjected to suction extraction for a much longer time than in the case of suction extraction of open width fabrics, previously described, using a longitudinally slit suction tube. It is not, therefore, necessary to apply such a high degree of vacuum to the interior of the hollow member(s), a vacuum of from 100 to 150 mm of Hg being sufficient for most purposes. Consequently, the material being treated is not sucked into the slots to any great extent and the tubular material can be moved through the apparatus, without damage to the material, at a faster speed than in the case of suction extraction of open width fabrics using a longitudinally slit suction tube. In practice, the speed of advance of the tubular material through the apparatus can be as high as 25 m/min., which is the same speed as that at which the tubular material could be advanced through a pair of squeeze rollers for expressing liquid therefrom. Consequently, by employing this preferred embodiment of the apparatus according to the invention, it is possible to pass the tubular material directly from a pair of squeeze rollers to the suction extraction means in a continuously operated process. In a practical embodiment of such a process, it may be necessary to take steps to ensure that the flattened form of the tubular material as it leaves the squeeze rollers is converted to open tubular form before it enters the suction extraction means. Various ways in which this may be done will be described in detail hereinafter. Again, it may be necessary to ensure that there is a loop of slack material between the squeeze rollers and the suction extraction means, to allow for variations in speed of the tubular material as it passes through the two liquid removal stages.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which

Figure 1 is a schematic perspective view of a first embodiment of a part of apparatus in accordance with the invention,
Figure 2 is a perspective view, on an enlarged scale, of a portion of a hollow member of the apparatus of Figure 1,
Figures 3, 4 and 5 are schematic perspective views of parts of second, third and fourth embodiments of apparatus in accordance with the invention,
Figures 6 and 7 are sectional views of details of the apparatus according to Figure 5,.
Figure 8 is a perspective view of apparatus in accordance with the invention in combination with a hot air drying means,
Figure 9 is a schematic perspective view of a jacket for use with the apparatus of Figure 8, and
Figures 10 to 12 are schematic sectional views of apparatus in accordance with the invention in combination with squeeze roller devices.

The apparatus shown in Figure 1 comprises two tubular members 1, 2 of rectangular cross-section. The member 1 is of V-shape, whereas the member 2 is straight. At its end 3 the member 2 is pivoted to the limb 1 a of the member 1, and the member 2 can be swung in the directions indicated by the arrows A over the V-shaped member 1 with its lower surface resting on the upper surfaces of the limbs 1 a and 1 b of member 1. The two hollow members 1 and 2 define a frame with a triangular window opening 4, the area of which can be adjusted by adjustment of the position of the member 2 relative to the member 1. Any suitable means (not shown) is provided for clamping the member 2 in a desired position relative to the member 1.
The walls 5, 6 of the member 1 which face the window opening 4, and the wall of the member 2 which faces the window opening 4, are all provided with a plurality of elongate, through-slots 7 disposed in parallel, closely spaced-apart relationship. Figure 2 shows a portion of the limb 1 b of the member 1. In this Figure, the arrow B indicates the direction of advance of the tubular material to be dried when it is advanced past the limb 1 b during use of the apparatus. It will be seen that the slots 7 are inclined to the arrow B by an angle C, which is suitably from 5 to 10 degrees. The slots 7 in the inwardly-facing walls of the limb 1 a and the member 2 are similarly inclined to the direction of advance of the tubular material through the window opening 4.
A tube is connected to the hollow interiors of the members 1 and 2, one end of this tube serving as a pivot for the end 3 of the member 2. The tube 8 is connectible by means of a further tube 9 to a source of vacuum (not shown).
In use of the apparatus shown in Figure 1, the tubular material 10 from which liquid is to be removed is advanced upwardly through a window opening 4, as indicated by the arrow B, and a sub-atmospheric pressure is created in the hollow interiors of the members 1 and 2 by connecting the tube 9 to the vacuum source. Prior to the liquid removal operation, the member 2 is adjusted relative to the member 1 to provide a window opening 4 having an area substantially equal to the cross-sectional area of the tubular material 10 and any of the slots 7 which lie outside the limits of the window opening 4 are masked with plates 11. Because of this adjustment, the tubular material will be in contact with the walls of the hollow members 1 and 2.
In the apparatus shown in Figure 3, the frame defining the rectangular window opening 4a through which the tubular material 10 advances in the direction of the arrow B, is formed by four straight, hollow members 12, 13, 14 and 15. Each of these hollow members has elongate slots 7 formed in its inwardly-facing wall, and the four members may have the same construction as the limb 1 b shown in Figure 2. The hollow interior of each of the members 12-15 is connected to a respective tube 16, these tubes being connectible to a source of vacuum (not shown). The members 14, 15 are supported on the upper surfaces of the members 12, 13 and they can be moved relative to the members 12, 13 to adjust the area of the window opening 4a to suit the area of the tubular material 10 passing therethrough. The members 14, 15 would be clamped to the members 12, 13 in any suitable way (not shown) after adjustment of the area of the window opening 4a. As in the case of the means described with reference to Figure 1, any of the slots 7 lying outside the limits of the window opening 4a are masked with plates.
In the apparatus shown in Figure 4, the frame defining the ractangular window opening 4b, through which the tubular material 10 advances in the direction indicated by the arrow B, is formed by a U-shaped hollow member 17 and a short straight hollow member 18 disposed between the limbs 17a and 17b of the member 17. Each of the hollow members 17, 18 has elongate slots 7 formed in each of its inwardly-facing walls, and both members may be of the same construction as the limb 1 b shown in Figure 2. The hollow interior of each of the members 17, 18 is connected to a respective tube 19, these tubes being connectible to a source of vacuum (not shown). The member 18 can have its position adjusted between the limbs 17a, 17b in order to adjust the area of the window opening 4b to suit the cross-sectional area of the tubular material 10 passing therethrough. The member 18 would be clamped to the member 17 in any suitable way (not shown) after adjustment of the area of the window opening 4b. As in the case of the previously described embodiments, any of the slots 7 in the member 17 lying outside the limits of the window opening 4b are masked with plates 11.
In the apparatus shown in Figure 5, the frame defining the oval window opening 4d through which the tubular material 10 advances in the direction indicated by the arrow B, is formed by two U-shaped hollow members 18, 29. The limbs 28a, 28b of the member 29 for the purpose of adjusting the cross-sectional area of the window opening 4d to suit the cross-sectional area of the tubular material 10. A rubber seal 30 is provided to seal the gap between each of the limbs of the member 29, these seals extending along the upper, lower and outwardly facing surfaces only of the members 28 and 29. Figure 7 shows the shape of the seals 30, this Figure being a sectional view through the seal between the upper surfaces of the limbs 28a and 29a. The inwardly-facing walls 28c and 29c of the hollow members 28 and 29, respectively, are each provided with elongate slots 7 throughout their length, these slots again being inclined to the direction of the arrow B as shown in Figure 2. As shown in Figure 6, which is a sectional plan of the walls 28c and 29c where the limb 28b enters the limb 29b, there is a close sliding fit between the walls 28c and 29c and the nose end of the wall 29c is curved to avoid a step-like transition so that the tubular material 10 will make continuous contact with the slotted walls 28c and 29c. The hollow interiors of the two members 28, 29 are connectible to a source of vacuum (not shown) by a tube 31 connected to the member 29.
To ensure that the tubular material arrives in open tubular form at the suction extraction means in order to ensure contact with all the slots in the inwardly-facing wall of the suction extraction means, the tubular material is passed in semi-collapsed or rope form upwardly through a ring-shaped, tubular member before reaching the suction extraction means. This tubular member has one or more inwardly-facing nozzles communicating with its hollow interior. Air under pressure is supplied to the tubular member via a pipe, and this air issues as jets from the nozzles. These air jets penetrate the tubular material and inflate it to open tubular form as it moves through the tubular member towards the suction extraction means.
Figure 8 shows one example of the suction extraction means of Figure 5 combined with a hot air dryer, for drying tubular fabric 10. The tubular fabric is drawn upwardly from a table 41 through the window opening 4d of the suction extraction means, and then through a drying chamber 43 by means of driven nip rollers 44, 45, following, as shown, a straight-line path without sharp bends. The arrow B shows the direction of advance of the tubular 10 in its passage between the suction extraction means and the drying chamber 43.
Pre-heated air under pressure is supplied to the drying chamber 43, as indicated by the arrow F, and the hot air penetrates the fabric 10 in the drying chamber and then flow downwardly in the tubular fabric, since its escape upwardly is hindered by the nip rollers 44, 45. Immediately below the drying chamber 43 the tubular fabric 10 passes over a stretcher 46 giving the fabric a more or less elliptical cross-section, indicated by the dotted line 47, as it enters the drying chamber. Below the stretcher 46, the fabric has a more circular cross-section, indicated by the dotted line 48.
In operation of the apparatus shown in Figure 8, the flow of hot air inside the tubular fabric 10, in the direction opposite to that in which the fabric advances, results in enhanced utilisation of the hot air, so increasing the drying capacity of the hot air dryer. The hot air, mixed with vaporised liquid from the fabric, is suction extracted by the hollow members 28, 29 connected to a vacuum source (not shown) by the tube 31. Liquid carried up to the suction extraction means by the fabric 10 is also extracted by the hollow members 28, 29. During use of the apparatus, the table 41 can be rotated by means of a turn-table 42, either by hand or by automatic means (not shown), to take out any twist which may occur in the tubular fabric 10.
In its passage from the suction extraction means to the drying chamber 43, the tubular fabric 10 may be surrounded by a heat-insulating enclosure. Such an enclosure is shown in Figure 9 and consists of two semicylindrical shells 49, 50 made of heat-insulating material and hinged together by a hinge pin 51. The shells 49, 50 are provided with observation windows 52 and one of the shells may be provided with an extraction duct 53 to encourage the flow of hot air downwardly in the fabric tube 10 and through the fabric.
Of course, a hot air dryer may be combined with any of the suction extraction means shown in Figures 1, 3 and 4 instead of the suction extraction means 28, 29 shown in Figure 8.
Figure 10 illustrates apparatus for drying tubular material which comprises the combination of a mangle, a suction extraction means 20 and a hot air dryer of the kind shown in Figure 8. Referring to Figure 10, the tubular fabric 10 from which liquid is to re removed enters a mangle comprising rollers 54, 55 over a stretcher 56 which ensures that the material enters the mangle in open tubular width and in basically crease-free condition. The tubular material 10 passes through the rollers 54, 55 in a horizontal direction and the rollers are urged together by weight or suitable hydraulic or pneumatic actuating means (not shown). The covering surface of one or both rollers may be made either from traditional rubber-type material or from one of the more recently introduced composition materials. The surface of one of the rollers may be metallic.
From the rollers 54, 55, the tubular material passes around a counter-balanced roller 57, the counter-balancing being provided by a counterweight 58 slidably adjustable on a lever arm 59. The position of the counterweight 58 in relation to the fulcrum 60 of the lever arm 59 is chosen so that the roller 57 has a tendency to move downwards if the mangle supplies more tubular fabric than is taken up by the nip rollers 44, 45 in the drying chamber 43. The movement of the roller 57 is transmitted electrically or mechanically (by means not shown) to a speed regulating device for the mangle, causing the latter to slow down when the roller 57 descends. In the opposite case, when the speed at which the nip rollers 44, 45 take up the tubular material 10 is faster than the speed at which the material is delivered from the mangle, the roller 57 will rise and this has the effect of increasing the speed of the mangle.
From the roller 57 the tubular material 10 passes upwardly, in the direction of the arrow B, through the suction extraction means 20 and then over a stretcher 46 into the drying chamber 43. The drying chamber functions in the same way as the drying chamber 43 of the apparatus shown in Figure 8.
Figure 11 illustrates a modified part of the apparatus of Figure 10 in which the tubular material 10 enters the mangle rollers 54a, 55a in the vertically upward direction over a stretcher 56a. From the mangle rollers the tubular material travels along a downwardly inclined path to the counterbalanced roller 57. In all other respects the apparatus of Figure 11 is the same as that of Figure 10, and like parts have been designated with the same reference numerals in both Figures.
Figure 12 illustrates another way of leading the tubular material 10 from the mangle rollers 54, 55 of the apparatus of Figure 10 to the suction extraction member 20. From the rollers 54, 55 the tubular material 10 is deposited on a counterbalanced scray 61, the counter-balancing of which is provided by a weight 58 slidably adjustable on a lever 59 mounted on a fulcrum 60. If a few folds of the tubular material accumulate in the scray 61, the latter falls into its lower position causing the slowing down or temporary stopping of the mangle rollers 54, 55. If, on the other hand, the length of tubular material 10 in the scray decreases to a permitted minimum, then the scray pivots about the fulcrum 60 to its higher position resulting in speeding up or restarting of the mangle.
From the scray 61 the tubular material 10 passes through a guide ring 62 to the suction extraction member 20. In all other respects the apparatus of Figure 12 is the same as that of Figure 10.
Of course, in each of the apparatus of Figures 10-12, the suction extraction means of any of Figures 1, 3, 4 and 5 may be used.

Claims

1. A method of reducing the liquid content of air-permeable material in tubular form, especially for reducing the moisture content of tubular fabric, by moving the tubular material longitudinally through means for applying suction to the external surface of the tubular material, characterised in that said means (1, 2; 12, 13, 14, 15; 17, 18; 28, 29; 20) for applying suction to the external surface of the tubular material (10) are adjusted in size so that an internal surface (5, 6) of the means is in contact with inflated tubular material passing through it, inflation of the tubular material being caused by gas introduced into the tubular material, and then exhausted from it through apertures (7) in said internal surface of the suction-applying means.

2. A method according to claim 1, characterised in that the tubular material (10) is moved from a source through drying apparatus in a straight-line, or substantially straight-line, path and past said surface (5, 6) in a direction parallel to said surface, the drying apparatus further including a chamber (43), downstream in relation to the direction of tubular material movement, from said suction-applying means (1, 2; 12, 13, 14, 15; 17, 18; 28, 29; 20) and pressurised to create a gas current into said tubular material (10); and nip-creating means (44, 45) downstream of said chamber (43) preventing gas current flow in the downstream direction from said chamber (43), whereby drying can be effected at rates of tubular material movement comparable with the rate of movement through squeeze rollers.

3. A method according to claim 1, or 2, characterised in that before moving through the suction-applying means (1, 2; 12, 13, 14, 15; 17, 18; 28, 29; 20), the tubular material (10) is moved through squeeze rollers (54, 55; 54a, 55a) for squeezing out part of the liquid content of the tubular material (10), the speed of rotation of the squeeze rollers (54, 55; 54a, 55a) being synchronised with the speed of movement of the tubular material (10) through the suction-applying means (1, 2; 12, 13, 14, 15; 17, 18; 28, 29; 20).

4. Apparatus for reducing the liquid content of air-permeable material in tubular form, especially for reducing the moisture content of tubular fabric, said apparatus comprising means for applying suction to the external surface of the tubular material, characterised in that said means (1, 2; 12, 13, 14, 15; 17, 18; 28, 29; 20) comprises hollow members (1, 2; 12, 13, 14, 15; 17, 18; 28, 29) defining a frame to surround said tubular material (10) and present an inwardly-facing surface (5, 6) thereto adjustable in circumference to become identical in size with the outside circumference of different sizes of tubular material (10), said surface (5, 6) being formed with apertures (7) communicating with the interior of the hollow members, and in that the apparatus further comprises means (44, 45) for advancing tubular material (10) through the frame to move the external surface of the tubular material (10) past said inwardly-facing apertured surface (5, 6), and means for inflating the tubular material by introducing gas into it to maintain it in open form and in contact with said surface (5, 6), whereby suction applied to the interior of the hollow members will create a gas current from within, and substantially only from within, the tubular material (10) through the said apertures (7) into the hollow members (1, 2; 12, 13, 14, 15; 17, 18; 28, 29).

5. Apparatus according to claim 4, characterised by the provision of a straight-line, or substantially straight-line, path for tubular material (10) through the apparatus and a chamber (43), downstream of said suction-applying means, in relation to the direction of tubular material movement, means for pressurising said chamber (43) to create a gas current into tubular material (10) within it and nip-creating means (44, 45) downstream of said chamber (43) preventing gas flow within tubular material in the downsteam direction from said chamber.

6. Apparatus according to claim 5, characterised in that said surface (5, 6) presented to the tubular material (10) comprises a plurality of zones (1 ; 2 and 12, 13; 14, 15) at least one of which is displaced from the other zone or zones of the surface (5, 6) in the direction of advance of the tubular material (10) through the apparatus.

7. Apparatus according to claim 5 or 6, characterised in that each of said apertures (7) in said inwardly-facing surface (5, 6) is in the form of a substantially straight, elongate slot having a length considerably greater than its width and disposed with its axis slightly inclined to the direction of advance (b) of the tubular material (10) through the apparatus.

8. Apparatus according to claim 7, characterised in that the axis of each of said slots (7) is inclined at an angle of from 5° to 10° to the direction of advance (b) of the tubular material (10) through the apparatus.

9. Apparatus according to any one of claims 5 to 8 characterised in that said nip-creating means (44, 45) downstream of said chamber (43) are constituted by nip rollers serving to advance the tubular material (10) through the apparatus.

10. Apparatus according to any one of the claims 5 to 9, characterised by a heat insulating jacket (49, 50) located between said suction-applying means (1, 2; 12, 13, 14, 15; 17, 18; 28, 29; 20) and said chamber (43) through which jacket the tubular material (10) advances in its passage from said means to said chamber.

11. Apparatus according to claim 10, characterised in that said jacket (49, 50) is provided with means (53) for exhausting hot air and vapour from a zone of the jacket disposed at or adjacent the end of the jacket lying nearer to said suction-applying means.

12. Apparatus according to any of claims 5 to 11, characterised in that the apparatus includes squeeze rollers (54, 55; 54a, 55a) disposed upstream of said suction-applying means (1, 2; 12, 13, 14, 15, 17, 18; 28, 29; 20) for squeezing out part of the liquid content of the tubular material (10) by passing the tubular material through the squeeze rollers, and means for synchronising the speed of rotation of the nip rollers with the means for moving the tubular material through the apparatus.

13. Tubular, air-permeable material whenever treated by the method of any one of claims 1 to 3 or in the apparatus of any one of claims 4 to 12.