GB2037188A - Applying treating liquids to textile webs - Google Patents

Abstract

Textile webs are coated and/or impregnated by contacting the running web 1 with the lower end of a sloping surface 31 down which the treatment liquid flows, the lower end of the surface being curved. <IMAGE>

Description

SPECIFICATION Method and apparatus for applying treating liquids to webs The invention relates to a method for applying treating liquids to webs, especially textile fabrics, by contacting the web with a treating liquid film which wets it and which is produced by allowing the liquid to flow downwards on a stationary planar oblique surface.

For carrying out this method an apparatus is provided which comprises a stationary planar oblique plate and means for dosing a treating liquid onto said plate.

It is known that by a uniform and controlled application of a treating liquid to running webs, particu larly textile fabrics, it is possible to coat and/or soak said webs whereby their mechano-physical, physico-chemical, chemical, physiological and other characteristics can be influenced.

Depending on the end use of such a treatment, the webs can be coated and/or soaked so as to regain a liquid amount within the range of from several tens to several hundreds per cent relative to the dry square weight thereof, which regain will hereinafter be called as wet pick-up. Preferably, such liquid applying process is to be effected atthe so called very low wet pick-up.

There exist many methods of an apparatuses for applying liquids to webs, wherein the application is, principally, carried out either by directly contacting the web with a liquid substance in the form of a continuous medium, or by spraying the liquid onto the web.

Among the first-named methods there can be mentioned the so-called pouring processes wherein the application is performed by allowing the treating liquid to flow down over the lower edge of a stationary oblique surface onto a web running below said edge in the perpendicular direction thereto.

The above well-known pouring processes distinguish from one another, on the one hand, in modes of supplying the oblique surface with liquid, and on the other hand, in modes of pouring the liquid on the web.

There is, for instance, known a process of supplying the oblique surface with liquid flowing down from an overflow edge of a bath trough, or out of a perforated or spraying tube, or out of slot extending across said oblique surface, viz. perpendicularly to the main inclination line thereof.

Another system is based upon an overflow edge of a trough while at the proximity of said edge and in parallel thereto an immersion roller rotates which roller doses an amount of liquid flowing over said edge.

Still another method of supplying the oblique surface with the treating liquid consists in that a doctor blade is associated with said immersion roller. The doctor blade assumes at the same time the function of the oblique surface.

Depending on the modes of pouring the liquid on the webs, there can be distinguished processes wherein the web either directly contacts the overflow edge, or runs at a distance of several millimetres below said edge. In the latter case, the liquid forms the so-called meniscus. According to a third type of such processes, the liquid is allowed to flow down onto the running web from a height, thus forming the so-calied curtain.

The inherent character of all the pouring processes resides in that they are suitable for treatments to relative high wet pick-ups (viz. 100 and more per cent of the web weight) and that with them the square evenness of the liquid film depends upon the viscosity of the treating liquid applied. Thus when using the above-mentioned liquid meniscus, or curtain applying process, it is necessary to choose liquids having a relative high viscosity, viz. from 10--2 to 5.10-2 Pa.s. In the latter case a specially shaped overflow edge has to be employed.

Unlike impermeable webs it is rather difficult with said pouring processes to obtain with porous webs uniform low per cent wet pick-ups, and particularly if the treating liquid viscosity exceeds 10-2 Pa.s.

The square evenness of a poured film depends further to a considerable extent on the range and uniformity of contact tension between the liquid and the web. The uniformity of the impregnation in the entire mass of a porous web analogously depends upon the uniformity of the boundary face tension, or uniformity of the absorbing capacity of the web. It is obvious that the use of the pouring processes is limited by the afore-mentioned factors.

Another disadvantage of the pouring processes within the range of very low wet pick-ups lies in the dependence of the film uniformity on the flatness of web surface. Porous webs, especially webs of textile character, are characterised by a structural, uneven or hairy surface. Also for this reason, it is difficult to obtain an even low pick-ups in these cases.

A higher film uniformity with a medium up to very low wet pick-ups is attainable by using the so-called padding technique (Pflatsch-prozess). In this process, a treating liquid film is produced on the surface of a rotary immersion roller and is transferred by contact onto a running web sliding on the top of said rolier. With cotton woven fabrics, a conventional medium wet pick-up varies as a rule within the range of from 55 to 80 per cent whereas a very low wet pick-up lies within the water retention range and even less, which means between 35 and 45 per cent.

One of the disadvantages of the afore-mentioned padding technique resides in a dependence of the pick-up upon the physico-chemical properties of both the treating liquid and the textile fabric. This shortcoming can be eliminated to a considerable extent by a padding system equipped with a pick-up regulator operating on the principle of comparing the desired pick-up value with the actual one. The wet pick-up is evaluated on the basis of difference in absorption of beta-ray emission before and after the film application. A drawback of such pick-up control means is in its complicacy and expensiveness since the pick-up is controlled indirectly, and the apparatus requires a frequent periodical gauging. As proved by practical tests, the actual pick-up values vary in this case within the range of +5 % of the adjusted value.

However, the fundamental disadvantages of the orthodox padding technique are not eliminated in the above way. They consist above all in the produc tion of an uneven pick-up which is caused by several factors. Among them there can be named.

bath turbulence in the proximity of the immersed pad-roll surface, causing variations in thickness of the film along its axis; a relatively low specific normal force attracting the web onto the roll surface, which force is incapable to provide the perfect contact with the web surface, especially with webs having a reduced flexibility or structural surface; and time and local variations in the application of liquid to the web, due to a relatively long web approaching distance to be covered before the outstanding and the depressed areas of the web get into contact with the treating liquid film.

The present invention eliminates the drawbacks of prior art, and it is an object thereof to provide an improved method of applying liquids to webs, espe ciallytextile fabrics, which method makes it possible to produce precise and highly uniform treating liquid coatings on the web surface, and particularly with very low wet pick-ups and low viscosity values of the liquid, and even on webs having structural surfaces as well as various absorbing capacities.

Another object of the invention is to provide a substantially not complicated and space-saving apparatus for carrying out this method.

These and other conditions are substantially complied with by a method of applying liquids to running webs such as textile fabrics by contacting the web with a film being formed from a liquid flowing down over a stationary planar oblique surface and wetting the web, the method being characterised, according to the invention, in that the liquid film is stripped by the running web off a curved surface and is in a sliding contact with said running web.

Depending upon the characteristics of both the treating liquid and the web, the local range of contact between the web and the curved surface can be chosen in such a manner that it takes place on a locally defined portion of said curved surface, or on the entire curved surface.

To safeguard the uniformity of the treating liquid film being applied to the web, especially a web with structural surface, the film can be preferably stripped off a curved zone defined by the transition between the stationary planar oblique surface and said curved surface.

The uniformity of the pick-up on the web surface is predominantly influenced by the magnitude of the so-called specific normal force which attracts the running web to the curved portion of the oblique surface, immediately after the web has contacted the liquid film, and by the steepness of gradient of said normal force, relative to time. The specific normal force related to a unit surface of the web is indirectly proportional to the radius of curvature. For a given tangential force indicating a longitudinal tension in the web, the normal force is, for instance, with the curvature radius of 1093 m, hundred times higher than with the curvature radius of 10-' m.Due to the effect of a higher normal force, it is possible to attain a better attraction of the web to the curved portion of the oblique surface, further an alignment of the web surface, an improvement in the contact between interior web parts and the treating liquid, and an improvement in capillary penetration of a low viscosity liquid through the web mass, due to a compression and consolidation of the latter. A relatively steeply ascending gradient of the normal force at the instant of the first contact between the web and the curved portion of the oblique surface causes the liquid to quickly intrude into the web whereby the influence of local variations in absorbing capacity upon the complete impregnation evenness is suppressed. Thereby one of the essential conditions of producing uniform films is complied with.

An even steeper ascending time-related gradient of the normal force attracting the web to the curved surface, and consequently a further improvement of conditions for an even film production is attainable when the first web/liquid contact occurs on the transition zone between the stationary planar oblique surface and the curved portion thereof. The curvature radius of such transition zone is about one digit lessex than that of the curved portion proper.

Due to the afore-mentioned sliding contact between the running web and the stationary curved surface, with higher normal force, a phase boundary between the treating liquid and the web surface is disturbed whereby the process of applying the liquid especially to webs with a reduced absorbing capacity is positively influenced.

Another advantage of the present invention consists in that a path on which a more or less even textile web approaches the line of contact with the treating liquid film, is due to the liquid applying geometry, substantially shorter than that existing with the orthodox padding technique. In this manner, both the outstanding and depressed areas of the web surface get into contact with the treating liquid within the substantially shorter time interval. Consequently, the intensity of capillary penetration of the liquid into said outstanding web areas to the detriment of said depressed areas, is suppressed whereby the film uniformity further rises.Such a positive effect is particularly availed of when applying low-viscosity treating liquids (within the range of 10-3 Pa.s.) and when treating webs with a relatively high absorbing capacity (e.g. 0.1 m .30-1. min-' and even more-see Czechoslovak Standard No. 80 0828) as well as webs with uneven surface.

Unlike the orthodox padding technique the thickness of the treating liquid film applied to the web is uniform across the entire web width. In accordance with the invention, it is possible to obtain a high square uniformity of the pick-up and, under the circumstances, also the uniformity of the impregnation throughout the web mass when applying a liquid having a viscosity beginning with the value of 10-4 Pa.s., and with medium but particularly very low wet pick-ups.

The apparatus designed for carrying out the method according to the present invention comprises a stationary planar oblique plate and means for supplying the liquid onto said plate, and is characterised, according to the invention in that said stationary planar oblique plate preceding a curved portion is associated with means for driving and means for guiding the web in the sliding contact with said curved portion.

The stationary planar oblique plate includes with the horizontal plane an angle of at most 20".

Preferably, the position of the stationary planar oblique plate is adjustable.

The zone of transition where the stationary planar oblique plate merges into the curved portion has a radius of curvature not exceeding 10 millimetres.

In a preferred embodiment, the curved portion of the oblique plate has a radius of curvature not exceeding 100 millimetres.

The web guiding means preferably comprise a pair of web guiding rollers position-adjustable relative to the transition between the stationary planar oblique plate and the curved portion thereof.

To provide an automatic control of the apparatus, incl. a weight control of the treating liquid film to be applied to the web surface, the web driving means, the web guiding means and the liquid supplying means are connected to a control unit designed for controlling the operation of said means, respectively.

To this purpose, the control unit comprises a first circuit for storing data of preselected wet pick-ups, a second circuit for storing data of web square weight, a third circuit for receiving data of peripheral velocity of outlet rollers for withdrawing the web from the apparatus, and a fourth evaluating a controlling circuit of a liquid dosing pump forming an element of the liquid supplying means.

Additionally, the control unit is provided with a fifth circuit for controlling the displacement of the pair of rollers into operative and inoperative positions, respectively, in dependence upon the web motion.

The apparatus according to the invention brings about the following advantages: By adjusting the slope angle of the planar oblique plate it is made possible to accomodate the apparatus to the viscosity and film building characteristics of the treating liquid. It can be stated in general, that low-viscosity and higher surface-tension treating liquids are to be applied to the web at smaller slope angles than high-viscosity liquids. It has been proved that at a relatively small slope angle of the plate it is possible to apply treating liquids having as high surface tension as preventing such liquids from being applied by means of an immersion roller at all.

Positive effects of the curved portion upon the film evenness in the apparatus of the invention manifest themselves markedly, beginning with the curvature radius of 100 millimetres, and further rise as the radius of said surface decreases.

A substantial improvement in the uniformity of the film to be applied to webs having an uneven and/or a considerably structural surface, orto poorly flexible webs, can be obtained when the web is caused to get into contact with the treating liquid film on the above-mentioned transition zone having a radius of curvature of 10 millimetres or even iess.

Another advantage of the apparatus according to the invention is the possibility of adjusting an optimum angle at which the textile web gets into contact with the treating liquid film on the curved portion, or on the transition zone between the stationary planar oblique plate and said curved portion thereof. In this way it is made possible to accomodate the liquid applying geometry to the properties of both the web and the treating liquid as well as to the character of the pick-up.

The merit of the apparatus of the invention resides in its simplicity and reliability. In contradistinction to the above-mentioned indirect pick-up control based upon evaluation of differences in beta radiation adsorption before and after the liquid applying process, a direct control is cared for by a control unit.

The unit is supplied with data of the desired pick-up value and with known data about the web square weight. The control unit then automatically controls the weight of the film to be applied, in dependence upon the velocity of the web passage through the apparatus. The exactness of the actual pick-up value varies here within the limits of +2 per cent of the desired value, and the apparatus need not be practically gauged.

Another advantage consists in an automatic displacement of the running web into the operative and inoperative positions, respectively, in dependence upon the web motion. In this way there are minimalized losses on untreated web caused by start and stop time intervals of the apparatus.

A preferred embodiment of the present invention will be hereinafter described with reference to accompanying schematic drawings in which Fig. 1 shows a side view of the entire apparatus; Fig. 2 is a detailed sectional view showing a part of the oblique plate and of the web guiding means in one of the operative positions; and Fig. 3 is a similar view as shown in Fig. 2 wherein the respective elements are illustrated in another operative position.

The entire apparatus according to the invention comprises, in general, means for driving and guiding a web and means for dosing and applying a treating liquid to said web.

Along the flow of the web 1 to be treated, the web driving and guiding means consists of a feed roller2, a tension compensating brake 3, a guide roll 4, a wet opener5, a pair of inlet rollers 6 with not shown driving means, a compensating roller7with a not shown position transmitter and an opening roller 9.

Close upstream ofthe latter, a suction slot8 is arranged which extends in parallel to the axis of said roller9 and corresponds to the length thereof. The suction slot8 communicates with a subatmospheric pressure source (not shown). The main part of the web guiding means is constituted by a pair of web positioning rollers 10 and 13 the positions of which relative to the running web 1 are adjustable, respectively. The position adjustment of said rollers 10 and 13 is cared for by control tierods 11 and 14, respectively, which are fixedly attached to respective bearing frames (not shown) receiving the bearings of the two web positioning rollers 10 and 13.

For a displacement of the first control tierod 11 and the second tierod 14 within selected time inter vals, a first servo unit 12 and a second servo unit 15 are provided, respectively.

At their outlet end, the web driving and guiding means are provided with a pair of outlet rollers 16 provided with a peripheral velocity transmitter (not shown). The drive of said rollers 16 is derived from the drive of another web finishing plant coupled downstream of the apparatus being described, in such way that the peripheral velocity of the outlet rollers 16 may correspond to the linear velocity of the web passing through said following finishing plant.

The liquid dosing and applying means comprise a reservoir 17 for a treating liquid, which reservoir 17 is provided with an outlet having a desliming valve 78 and with a connecting pipeline 19 which comprises afirstshut-offvalve20 and a main filter21.

The end of said connecting pipeline 19 opens into a manipulation tank22 with a manipulation outlet and a manipulation desliming valve23. At the bottom of the manipulation tank22, the end of a suction pipeline 24 opens, which pipeline 24 leads to a liquid dosing pump25 with not shown drive means. From the liquid dosing pump25 there extends a discharge pipeline 26 opening into a bath trough 27 equipped with a device 28 for uniformly distributing the liquid along the trough width, further with one or more defoaming plates 29 and with a liquid film forming overflow edge30 which latter is affixed to said bath trough 27. The lower portion of the bath trough 27 is actuated by a not shown device for levelling the overflow edge30 in horizontal plane.

The liquid applying means constituting also one of the main components of the apparatus according to the invention comprise a stationary planar oblique plate 31 merging via a transition zone 32 into a curved portion 33. The lefthand edge of said plate 31 (see Figure 1) is provided with two bushes35 through which an axle 34 passes; the axle 34 is secured to two opposite brackets 36 fixedly attached to the bath trough 27. A desired inclination of the stationary planar oblique plate 31 can be adjusted by an adjusting screw device 37. The transition zone 32 between the plate 31 and the curved portion 33 thereof has a curvature radius usually varying between 10-3 and 10-4 m while the curvature radius of said curved portion 33 is 10-1 m at the most.

Below the curved portion 33 of the plate 31 there is arranged a liquid collecting trough 38 provided with a return pipeline 39 equipped with a cleaning filter 40. The return pipeline39 opens atthe bottom of the manipulation 22.

The bath trough 27 is further provided with a draining pipeline 41 which also opens at the bottom of the manipulation tank22 and is equipped with a drain valve 42.

All the web driving and the web guiding means as well as the means for dosing the treating liquor are connected to a control unit43 designed for control ling the operations thereof. The control unit 43 com prises a first circuit for storing data A of a predeter mined wet pick-up, a second circuit for storing data B about sqaure weight of the web to be processed, a third circuit for receiving data of peripheral speed of the outlet rollers 16 for withdrawing the web from the apparatus, and a fourth evaluating and controlling circuit of the liquid dosing pump25 forming a part of the web dosing means. Apart from this, the control unit is provided with a fifth circuit for adjusting the operative and inoperative positions of the pair of web positioning rollers 10 and 13, respectively.As hereinabove set forth, said rollers 10 and 13 are positionally adjustable relative to the transition zone 32 by which said stationary planar oblique plate 31 merges into the curved portion 33, depending upon the web motion.

Additionally, the control unit 43 is provided with a sixth circuit for receiving data from the above mentioned transmitter (not shown) about the position of the compensating roller 7. This compensating roller 7 is situated between the pair of inlet rollers 6 and the pairofweb positioning rollers 10 and 13. Finally, the control unit comprises a seventh circuit for evaluating the above compensating roller position data, and an eighth circuit for controlling the drive of the inlet rollers 6.

Figure 2 shows a detailed sectional view of a part of the stationary planar oblique plate 31 comprising the transition zone32 and the curved portion 33, and of the pair of web positioning rollers 10 and 13 which are adjusted in a position causing the web 1 to strip the treating liquid film of said curved portion 33. As apparent from this Figure, the plate 31 forms an angle alpha = 3 with the horizontal plane.

Figure 3 shows the same view as Figure 2, with the exception that the web positioning rollers 10 and 13 assume such position relative to the oblique plate31 that the liquid film is applied to the running web 1 from the transition zone 32. The angle alpha included by the plate31 and the horizontal plane equals to 12'.

The entire apparatus according to the invention is installed in a support frame structure which, for the sake of clarity, is not illustrated in the drawing.

The afore-described apparatus constitutes one of a plurality of possible embodiments or arrangements.

It is obvious to use two or more such apparatuses installed seriatim for applying the liquid to one or both sides of the web 1.

Underthe circumstances, another liquid film can be applied to the web with or without an intermediate drying step. in other cases, it may be advisable, after the treatment and before a further processing such as drying or any other technological step, to let the web mature in batch. It is also possible to combine the process according to the invention with a padding technique.

The apparatus according to the invention operates as follows: A web 1, such a textile fabric, supplied from a preceding finished plant (not shown) such as a tenter frame or web supply means such as, for example, a cloth beam or a pallet, enters the apparatus via feed roller2, compensating brake3 and passes over the guide roll 4 to the opener5 and the inlet rollers 6.

The latter impart to the web a tension necessary for being withdrawn from said preceding finishing plant, or a web supply, and for feeding it at a constant speed via compensating roller 7, suction slot8 and opening roller9 to the actual film applying means. The perfect operation of the opener 5 is conditioned by an appropriate adjustment of the compensating brake3 in a position to give the web 1 a necessary tension. The suction slot8 is designed for removing impurities adhered to the web surface and impairing either directly or indirectly, due to a contamination of the film before being applied, the pick-up uniformity.

The synchronization of the peripheral velocity of inlet rollers 6 with that of the outlet rollers 16 at a preselected constant longitudinal tension in the web 1 during its passage through the actual film applying means, is cared for by the compensating roller 7 equipped with a not shown position transmitter as well as bytheafore-mentionedsixth circuit of the control unit 43 for receiving the data transmitted by said transmitter. In this way, it is possible to attain the web passage through the film applying means at a linear speed W which is given by the peripheral velocity of said outlet rollers 16 at a constant longitudinal web tension proportional to an effective force P causing the compensating roller 7 to rise.In this manner, it is possible to compensate for any web length modifications which may be caused, for instance, by the contact of the web with the liquid.

The intensity of the force P exerted on the compensating roller 7 is given by the weight of an additional load acting via a roll (not shown). The weight of said load and, consequently, the longitudinal tension in the web 1 is chosen with respect to the web character and to the properties of the treating liquid. With light weight webs, the longitudinal tension should vary within the range of from 10 to 40 N. m-1, with medium weight webs between 40 and 120 N.m-l and with heavy webs 120 N.m-1 and even more.

The inlet rollers 6 are designed for further compensating for variations in the linear speed of the web 1 withdrawn from a cloth pallet, or from an unbalanced or improperly let-off cloth beam.

The speed at which the web 1 passes through the actual film applying means practically corresponds to the peripheral velocity W of the outlet rollers 16. It is determined by technological parameters of the finishing line in which the film applying apparatus is installed, further by the character of the web 1 to be treated, of the treating liquid, and by the effect to be obtained. The speed W usually varies between 0.1 and 2 m.s.-l.

An indispensable condition for attaining an even and reproducible liquid film coating is also a continuous passage of the web 1 through the film applying unit, which means the passage without variations in longitudinal tension and speed.

Another condition therefore is a perfect function of the opening roller 9. As well this function depends, to a considerable extent, upon the longitudinal tension in the web 1.

The position of the web 1, when passing through the web applying means, relative to the transition zone 32 and, consequently, to the curved portion33 of the stationary planar oblique plate 3 1 is controlled by the pair of positionally adjustable rollers 10 and 13.

On the one hand, said roller pair controls the passage of the web along the operative path between the rollers 10 and 13 (see full line in Figure 1), and along the inoperative path therebetween (see dashline in Figure 1).

On the other hand, the pair of rollers 10 and 13 controls the inclination of the web 1,which inclination locally defines a section of the curved surface on which the web contacts the treating liquid film as well as the inclination at which the web approaches said curved surface and at which it leaves it. On principle, the web 1 can get into contact with the liquid film on the transition zone 32 and/or on said curved portion 33. After having stripped the film of the plate 31, the web 1 can leave it as early as on the transition zone32, or till on the curved portion 33.

The choice of the afore-mentioned locally defined curve surface section on which the web 1 gets into contact with the treating liquid film and simultaneously the choice of the inclination at which the web 1 approaches and leaves the stationary planar oblique plate 3 1, respectively, depend particularly upon the characteristics of the treating liquid, the web as well as on the effect to be obtained. Such a locally defined section substantially influences the intensity and behaviour of the so-called specific normal force which attracts the web 1 to the curved surface as well as the length of the section on which the projected and depressed areas of the web surface will contact the treating liquid. For this reason, the evenness and depth of the impregnation are also influenced by said locally defined section of the plate 31.

The displacement of the respective rollers 10 and 13 to and from the operative and inoperative positions, respectively, at a desired web inclination, is carried out by means of the first control tierod 11 and the second tierod 74 through the servo units 12 and 15, respectively. These units are in turn controlled by the fifth circuit of the control unit43, designed for adjusting the operative and inoperative positions of the rollers 10 and 13. It is to be understood that the fifth circuit controls the web displacement between the two positions in dependence upon the web motion which means that when the apparatus is started the web 1 is automatically displaced into the operative, i.e. film applying position while at the stop instant, it is, also automatically, displaced into the inoperative position in which the film is not applied.

In such a way the losses caused by the delivery of untreated web are reduced to a minimum.

The treating liquid flows out of the reservoir 17 through the connecting pipeline 19 via the first shut-off valve 20, and is further conveyed over the main filter21 where it is freed of impurities whereupon it is accumulated in the manipulation tank22.

Therefrom it is drawn through the suction pipeline 24 and conveyed by the dosing pump 25 via discharge pipeline 26 to the bath trough 27. The flow velocity profile of the liquid which at first rises to the level, is aligned over the entire width of the bath trough 27 by a special device28. From the level, the liquid flows in the opposite direction downwards, i.e.

below the defoaming plate 29, which, on the one hand, prevents the foam from entering the applying process and, on the other hand, assumes the function of additionally levelling said flow velocity profile of the liquid passing upwards to the overflow edge 30. As the liquid flows over said overflow edge30 it forms a liquid film which streams downwards onto the oblique plate 31.

To obtain a uniform thickness of the treating liquid film and simultaneously a uniform square weight of the film to be spread over the entire surface of the web 1, the overflow edge30 as well as the main lines of the oblique plate the transition zone 32 and the curved portion 33 have to lie in the horizontal plane.

Since the axis of the axle 34 extends in parallel to the upper edge of the overflow edge 30 as well as to the afore-mentioned main lines, it is possible, by adjusting said edge into the horizontal plane by means of a not shown device actuating the lowermost part of the bath trough 27, to attain the horizontal position of said main lines. Due to the flow of the treating liquid film downward over the oblique plate31, its layer is getting thinner, more uniform, and the thus arisen laminar flow is stabilized. After the treating liquid film has covered a certain distance on the oblique plate 31, the evenness of its thickness over the entire plate width and the laminar character of its flow correspond to the conditions necessary for obtaining a uniform pick-up.The above-mentioned distance depends upon the viscosity of the treating liquor and on an angle alpha formed by the slope line of the plate31 together with the horizontal plane. This angle can be varied within the aforementioned range by means of the adjusting screw device 37. Underthe circumstances, the length of said distance may vary between 0.05 and 0.30 m.

With liquids having a viscosity of up to 10-2 Pa.s. it is preferable when the angle alpha does not exceed the value of 6 while with higher viscosities the angle values can be also higher. The first-mentioned case is illustrated in Figure 2 while the second in Figure 3; apart from this, the latter case is preferred when it is desired to press the liquid more intensely into the web structure.

The treating liquid film which is capable of being applied and which is defined, for example, by the weightthroughflow over the entire width of the plate 31, is formed by dosing the liquid by means of the dosing pump 25 the operation of which is controlled by the control unit43. As hereinabove set forth, the first circuit of said control unit43 stores the wet pick-up data A while its second circuit stores the data B of the web square weight. The third circuit of the unit 43 receives the data about the peripheral velocity of the outlet rollers 16. The fourth circuit of the control unit43 is designed for evaluating the three last-mentioned data and for controlling the rotational speed of the dosing pump 25 which delivers the predetermined amount of treating liquid.

Thus, for instance, when a textile fabric (bone dry square weightA = 0.147 kg.m-2) is to be impre gnated to the wet pick-up B = 47.0 % at the web linearvelocityW = 1.5 m.s-',the predetermined weightthroughflow Q related to one meter of width of the oblique plate 31 is given by the equation Q = A . B .100-l . W = 0.147 kg.m-2.47.100-' .1.5 m.s-' = 0.1036 kg.m-1.

The determining parameters of the film applying process are in practice always chosen in such a manner that the treating liquid film is quantitatively applied to the web at a preselected weight throughflow.

The surplus amount of the treating liquid which flows downward on the curved portion 33 of the oblique plate31 in the film form and which does not get into contact with the web 1, falls into the collection trough 38 and after having passed through the cleaning filter40, it is returned into the manipulation tank22.

It is an object of the present invention to substitute the orthodox hitherto used web impregnating technology. Unlike such technology the process according to the invention possesses the merit consisting in that it makes it possible to treat such substrates on one side and/or on both sides orthroughouttheir mass at a lower wet pick-up and at a substantially lower mechanical stress.

A well-known advantage of the treating processes effected at unconventionally low wet pick-ups resides in energy savings during the subsequent drying step and in obtaining a more uniform distribution of the treating liquor in the entire web mass wherefrom a higher quality of finish and simultaneously saving of treating agents result.

However, in contradistinction to prior art wherein webs can be also treated at unconventionally low wet pick-ups, the present invention brings about many considerable advantages.

The invention makes it possible to apply highly uniform and reproducible pick-ups to webs having both smooth, flat and structural surfaces as well as a higher or lower flexibility. Further the invention enables an optimalization ofthe liquid applying technique with regard to all the important and determining parameters of the process.

The above-mentioned high both pick-ups and impregnation evenness attainable according to the present invention meets even the claims laid on the pad-dyeing technique. A considerable adaptability of the apparatus according to the invention to the determining parameters of the film applying process is particularly given by the following factors: A possibility of preparing, before the actual applying step, highly uniform films from treating liquids having various viscosity values.

A possibility of dosing or metering exact liquid amounts onto the web.

The use of such applying geometry that enables the liquid to be applied to the web while exerting a much higher specific normal force than with other types of similar apparatuses. Such higher specific normal force effectively contributes to the penetration of the liquid into the web structure and improves the quantitative transfer thereof onto the web.

The use of such applying geometry that makes it possible to vary the specific normal force and the gradient of its increase with both the web and liquid characteristics in view. This further enables all the negative influences of uneven surface and structure of the web as well as of local variations in web absorption capacity and liquid viscosity on the film and impregnation uniformity to be suppressed.

Additionally, the specific normal force can be modified by varying the longitudinal tension in the running web.

A high preciseness of dosing the treating liquid on the web and the optimalization of the liquid applying conditions make it possible, with one-side coatings, to control the depth of liquid penetration into the web mass.

In accordance with the invention, a direct wet pick-up control is availed of. Such a control is precise, reliable and makes frequent gauging unnecessary.

The apparatus according to the invention is simple and space-saving. Because of the limited floor space it occupies, it can be installed as a unit of finishing plant lines for one or more liquid applying and/or web impregnating steps. Adaptations of orthodox finishing lines by substituting a padding machine, or by adding the apparatus of the invention to the existing lines is possible without expensive and complicated reconstructions.

The following examples of technological applications are given as illustrative only without, however, limiting the invention to the specific details thereof.

EXAMPLE 1 A conventionally pretreated and printed all-cotton woven fabric (warp 12 tex, weft 12 tex, 41/31 sett, 0.08 kg.m-2 square weight, 0.07 to 0.09 m.30-1 min.-t absorption capacity-CSN 80 0828) was impregnated with a treating bath containing 10 g/litre softener based on a polyethylene emulsion having 40 % by weight of active substance, 10 gllitre wetting agent based on alkyl sulphate having 50 % by weight of active substance, 20 gllitre glycerine.

The impregnation was effected by applying the bath in the apparatus according to the invention up to 30 per cent wet pick-up at the web motion velocity of 1.5 m.s.-'. The fabric was then continuously dried on a tenter frame at 110 C up to 6-8 per cent residual moisture.

The result was a fabric having a soft supple hand comparable with that obtained on a padding machine by impregnating the fabric to 80 % wet pick-up with a bath comprising 5 g/litre of the above softener 6 g/litre of the above wetting agent 10 g/litre of glycerine and subsequently drying under comparable conditions at the linear fabric motion velocity of 0.92 m.s-'. Thus the apparatus of the invention made it possible to obtain the desired effect at 164 % of the original drying capacity and at 25 % economy of active components of the impregnating bath.

EXAMPLE 2 A conventionally pretreated all-cotton woven fabric (warp 29.5 tex, weft 35.5 tex, 23/16 sett, 0.125 kg.m--2 square weight, 0.07-0.09 m.30-'. min.-t absorption capacity-CSN 80 0828) was impregnated with atreating bath containing 27 g/litre of a product based on polyvinyl acetate having 35 % by weight of active substance 4.5 g/litre of a product based on highly sulphated castor oil having 80 % by weight of active substance.

The impregnation was carried out to 35 % wet pick-up and the fabric was then dried on a tenter frame at 120"C to a residual moisture of from 7 to 9 % at the passage velocity of 1.47 m.s~~' There was obtained a stiffer, fuller and washproof handle which was comparable with the effect attainable by impregnation in a padding machine. Unlike the orthodox process of impregnation to 78 per cent wet pick-up followed by drying in the same plant at 120"C and at the passage velocity of 0.75 m.s~~', the drying capacity rose to 196 %. Due to a more uniform distribution of the wet content in the material mass,19 saving of the active impregnation bath component was reached.

EXAMPLE 3 A conventionally pretreated mercerised and printed all-cotton woven fabric (warp 29.5 tex, weft 29.5 tex, 26/23 sett, 0.149 kg.m-2 square weight, 0.10 to 0.11 m.30--1. mien~~' absorption capacity-CSN 80 0828) was impregnated to 40 % wet pick-up in the apparatus according to the invention with a treating bath containing 160 g/litre of a product on the basis of dimethyloldihydroxyethylene urea having 40 % by weight of active substance, 20 g/litre of a product on the basis of hexamethylolmelamine precondensate having 50 % by weight of active substance, 6 g/litre glycerine, 12 g/litre of a product on the basis of polyethylene emulsion having 40 % by weight of active substance, 9 g/litre of a product on the basis of polyvinyl acetate emulsion having 35 % by weight of active substance, 20 g/litre magnesium chloride hexahydrate, 20 g/litre of buffered latent acidic catalyst having 50 % by weight of active substance, 0.08 gllitre of a optical brightener.

The fabric was then dried on a tenter frame at the velocity of 1.17 m.s-t and at the temperature of 120"C to the residual moisture content of 9.9 %, whereupon it was heat treated by passage through a condensation oven with 4 minutes' dwell at 155"C.

The thus treated woven fabric obtained a fuller handle, crease resistance and no-iron character, which properties were accompanied by lower losses on strength than usual with orthodox padding techniques. This was proved by a parallel test in which the same fabric was impregnated in a padding machine to 80 per cent wet pick-up with a bath containing 92 g/litre dimethyloldihydroxyethylene urea, 11 g/litre hexamethylolmelamine precondes nate, 5 g/litre glycerine, 10 g/litre polyethylene emulsion, 5 g/litre polyvinyl acetate emulsion, 11 g/litre magnesium chloride hexahydrate, 11 g/litre of buffered latent acidic catalyst, 0.46 g/litre of optical brightener.

The treatment was followed by drying on a tenter frame at 120"C, at the velocity of 0.58 m.s-1 and by applying the same heat treatment in a condensation oven as in the preceding case.

The two fabrics were conditioned together for 48 hours at 20"C and 65 % R.H., and then subjected to tests of representative mechano-physical properties.

The results of the tests are tabulated hereunder: Treatment in the Treatment in the apparatus of the Test padding machine invention dry tensile strength warp 307 (N) 294 (N) weft 165 (N) 167 (N) tear strength warp 11,196(mN) 15,486 (mN) weft 11,405 (mN) 16,324(mN) surface smoothness 5th washing at40 C (DURABLE PRESS) 3.3 3.4 angle of recovery after 5th washing at40 C (warp/weft average) dry 101(o) 124 (o) wet 103(o) 116(o) As results from the table of values, the apparatus according to the invention makes it possible to achieve, with comparable dry tensile strengths, a higher tear strength, better surface smoothness and better angles of crease recovery, which means better utility values than those attainable by using orthodox padding technique.Apart from this, these results were obtained at double drying velocity under comparable conditions and with about 20 per cent saving of reactant, catalyst and film building ingredient.

EXAMPLE 4 The pile face of a dyed ribbed corduroy (warp 25/2 tex, weft 35.5 tex, 18.7/74.5 sett, 0.370 kg.m-2 square weight) was impregnated in the apparatus according to the invention with a bath containing 250 g/litre of a softening oil-in-water emulsion on the basis of sulphated fats and paraffins having 50 % by weight of active substances, and continuously dried on a tier stenter at the temperature of 150"C and at the velocity of 0.42 m.s-1 to a residual moisture content of from 8 to 9 per cent.After finishing treatment (pile brushing and steaming) there was obtained a soft full handle and dull lustre the uniformity of which was not achievable by orthodox process such as waxing from a melt, or impregnating by immersing the fabric in a bath and subseqeuntly squeezing in a padding machine.

Due to a very low moisture content after the pile impregnation in the apparatus of the invention, possibilities are given for two different one-side treating steps, either without intermediate drying, or with an intermediate drying step with a relatively low heat demand. Thus it is made possible, for instance, to effect in the one apparatus of the invention, a back pile treatment with using a suitable bath, and subsequently in another apparatus according to the invention, a pile face treatment by means of the bath having the afore-mentioned composition.

For the case it may be necessary to coat the back with a relatively large amount of treating liquid, it is possible to precede the face treatment buy a mild intermediate drying step. Apart from the abovementioned advantages, it is possible to reduce the drying heat demand up to a half of that required in the orthodox process.

EXAMPLE 5 A conventionally pretreated all-cotton fabric (warp 29.5, weft 35.5,23/16 sett, 0.125 kg.m-2 square weight, 0.07 to 0.09 m.30~~'.min~~t-CSN 80 0828) was printed on a roller printing machine to a one-colour contour pattern with a primary printing dye.

Printing dye composition: 20 g pigment printing dye (Pigment Blue 15-Color Index) 10 g 50 % ammonium sulphate solution 970 g thickener 1000 g printing dye Thickener composition: 25 g synthetic thickener on the basis of a polycar bonic acid (e.g. Acraconz O) 20 g synthetic thickener on the basis of a maleic acid polymer (e.g. Lutexal U) 150 g pigment dye binder on acrylate basis (e.g.

Helizarin-binder TR) 805 g water 1000 g thickener The printed fabric was dried in a conventional way and dyed by applying a dye to the face in the apparatus according to the invention.

Dye bath composition: 80 g pigment dye binder on acrylate basis (e.g.

Helizarinbinder FA) 6 g pigment dye for dyeing (Pigment Yellow 83-Color Index) 5 g non ironic wetting agent (e.g. Vitexol PFA) 5 g anionic wetting agent on the basis of sodium dialkylsulphosuccinate (e.g. Spolion 8) 3 g ammonium chloride 901 9 water 7000 g dye bath The fabric impregnated to 38 % wet pick-ups was continuously dried on a tenter frame at 120 C and heat treated for 5 minutes in a condensation plant at 150"C.

There was obtained a primary blue contour print on a medium deep level golden-yellow ground. The uniformity of the ground colour attained in the apparatus according to the invention was comparable with an orthodox coloration on a padding machine, with the exception that it was obtained at a substantially lower drying heat demand.

The relatively low wet pick-up makes it possible to suppress in the apparatus of the invention the migration of dye to such an extent that the coloration level is excellent even without using any anti-migration agent. The thus obtained fastness values of pigment print and of ground pigment coloration are comparable with those achieved by orthodox techniques.

EXAMPLE 6 A conventionally pretreated all-cotton woven fabric (warp 12 tex, weft 12 tex, 41/31 sett, 0.08 kg.m-2 square weight, 0.08 m.30-1.min- absorption capacity-CSN 80 0828) was impregnated in the apparatus of the invention with a treating bath containing 40 g/litre of a product on the basis of dimethyloldihydroxyethylene urea having 40 % by weight of active substance 80 g/litre of a product on the basis of hexamethylolmelamine precondensate having 50 % by weight of active substance 30 g/litre glycerine 20 g/litre of a product on the basis of polyethylene emulsion having 40 % by weight of active substance 50 g/litre pigment dye binder on acrylate basis (e.g. Helizarinbinder FA) 5 litre nonionic wetting agent (e.g. Vitexol PFA) 15 g/litre magnesium chloride hexahydrate 3.5 gllitre pigment dye for dyeing (Pigment Green 7-Color Index).

The fabric impregnated to 42 % wet pick-up was then continuously dried on a tenter frame at 11 0'C, and finally treated on a Schreinercalender. Thus the fabric obtained a level pastel green colour and a silky lustre-due to Schreiner finish-and a fuller handle.

Apart from a lower drying heat demand, it is preferable, from the economical point of view, to unite the dyeing and the finish treatments into a single step.

Claims (14)

1. In a method of applying liquids to running webs such as textile fabrics by contacting the web with a film being formed from a liquid flowing down over a stationary planar oblique surface and wetting the web, the improvement in which the liquid film is stripped off by the running web a curved surface preceded by said oblique surface and is in a sliding contact with said running web.

2. A method as claimed in claim 1, wherein the film is stripped off a locally defined zone of the curved surface.

3. A method as claimed in claim 1 and claim 2, wherein the film is stripped off a curved zone defined by a transition between the stationary planar oblique surface and the curved surface.

4. In an apparatus for carrying out the method as claimed in claim 1, comprising a stationary planar oblique plate and means for supplying the liquid onto said plate, the improvement wherein said stationary pianar oblique plate (31) preceding a curved portion (33) is associated with means for driving and means for guiding the web (1) in a sliding contact with said curved portion (33).

5. An apparatus as claimed in claim 4, wherein the stationary planar oblique plate (31) includes with the horizontal plane an angle (alpha) of at most 20 .

6. An apparatus as claimed in claim 4 and claim 5, wherein the position of the stationary planar oblique plate (31) is adjustable.

7. An apparatus as claimed in claim 4, wherein a zone (32) of transition where the stationary planar oblique plate (31) merges into the curved portion (33) has a radius of curvature not exceeding 10 mm.

8. An apparatus as claimed in claim 4 and claim 7, wherein the curved portion (33) has a radius of curvature not exceeding 100 mm.

9. An apparatus as claimed in claim 4 and claim 7, wherein the web guiding means comprise a pair of rollers (10,13) the position of which is adjustable relative to the transition zone (32) on which the stationary planar oblique plate (31) merges into the curved portion (33).

10. An apparatus as claimed in claim 4, wherein the web driving means, the web guiding means and liquid supplying means are connected to a control unit (43) for controlling the operation of said means.

11. An apparatus as claimed in claim 10, wherein the control unit (43) comprises a first circuit for storing data (A) of preselected wet pick-up, a second circuit for storing data (B) of web square weight, a third circuit for receiving data of peripheral velocity of outlet rollers (16) for withdrawing the web from the apparatus, and a fourth evaluating a controlling circuit of a liquid dosing pump (25) forming an element of the liquid supplying means.

12. An apparatus as claimed in claim 9 and claim 10, wherein the control unit (43) is provided with a fifth circuit for controlling the displacement of the pair of rollers (10, 13) into operative and inoperative positions, respectively, in dependence upon the web motion.

13. A method substantially as hereinbefore described with reference to the accompanying drawings.

14. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.