GB2154255A

GB2154255A - Treating material webs with liquid

Info

Publication number: GB2154255A
Application number: GB08503643A
Authority: GB
Inventors: Lenart Lyman
Original assignee: Calator AB
Current assignee: Calator AB
Priority date: 1984-02-16
Filing date: 1985-02-13
Publication date: 1985-09-04
Also published as: IT1183192B; JPS60185856A; ES8602994A1; FR2559795A1; GB8503643D0; SE8500687D0; ZA851133B; DE3505091A1; ES540431A0; SE8500687L; IT8519516A0

Abstract

Woven material (2) in hose form is treated with liquid by being passed through a bath (3), expanded to a bladder-like configuration (6; 9) so as to smooth and straighten out the material, and then passed between two counter- rotating pressure rolls (10) where surplus liquid is pressed from the material. The pressure rolls have extending therearound a porous covering (14) having a thickness of 10-15 mm. In this way there is formed in the direction of material travel a relatively long contact zone (22) having a forwardly located infeed zone (23) and a downwardly connecting outlet zone (24), within which zones liquid is transferred from the passig product while the product undergoes an intensive and equalizing final treatment process at the same time. <IMAGE>

Description

SPECIFICATION A method for treating material webs with liquid The present invention relates to a method of the kind set forth in the preamble of Claim 1.

The method also relates to apparatus for carrying out the method according to Claim 1.

The invention can be used in all circumstances where a web of material of any kind whatsoever is subjected to treatment with liquid, although it particularly relates to methods and apparatus for treating with liquid woven material in hose form, for example the treatment of knitted goods in dye bath.

Particularly in this latter case, circular knitted goods for example are passed over deflecting rollers through a dye bath or a plurality of such baths, to be then inflated and therewith smoothed and straightened out, whereupon the web is passed between at least one pair of counter-rotating pressure rolls, wherewith surplus liquid is pressed out at the same time as a first de-watering or drying of the web takes place, the web then being passed, for example, to a reeling station where it is taken up on reels.

It has been found that when passing through the contact zone between the pressure rolls knitted goods, and particularly certain knitted goods, become miscoloured, to produce lighter or darker stripes thereon, these stripes usually occurring at the edge zones of the woven hose-like material. In these zones the two sides of the hose do not lie flat against one another, but that the yarn or the like located at said edge zones is deflected through 180 , thereby to create a deviating physical structure such that the material in these zones is not treated to the extent desired, causing miscolouring of the material.

Such miscolouring of the material may also be due to the presence of cavities which extend vertically in the contact zones in the longitudinal direction of the pressure rolls in the vicinity of the material web and into which cavities liquid can accompany the web, whereupon the web is again able to take up liquid at the outfeed zone of the pressure rolls and entrains this liquid which is then exclusively absorbed and retained by the edge zones of the web.

The total material web zone within a treatment bath and in the vicinity thereof is extremely sensitive, not least because of the requisite high working rate of, for example, approximately 0.5 m/sec. This can mean, for example, that a web of material passes from the entrance to a pigment bath and the outfeed zone of the pressure rolls within a period of from 2-8 seconds, and shall be hogoenously dyed during its travel through this path and within the aforesaid time period. It will be readily understood in this respect that a certain degree of miscolouring and/or some other happening can take place in connection with or in the vicinity of a pigment bath or dyer's bath, which as the result of the least irregularity or deviation can be detrimental so as to result in an unevenly coloured article, in the aforedescribed manner.

Attempts have been made to prevent or to lessen the aforesaid miscolouring conditions by increasing and decreasing the abutment pressure of the rolls and to increase and decrease respectively the rate at which the material web pases therethrough. These tests have been unsuccessful, however.

The object of the present invention is to provide means whereby the aforesaid miscolouring conditions are avoided to the greatest possible extent and as completely as possible.

At the same time it is a further object of the invention to advance the state of the art in this field in various respects, for example by enabling an increase in the throughput rate, at least with respect to certain kinds of material, and to provide for gentler treatment of sensitive types of material and/or simply shortening a treatment path and thus providing conditions for less expensive methods and apparatus of this kind.

This object is achieved in accordance with the invention by carrying out a method of the kind mentioned in the introduction substantially in the manner set forth in the characterizing clause of claim 1. The object is also achieved with the aid of the apparatus claimed in the first apparatus claims.

Additional features and advantages of the invention are made apparent in the following description, which is given with reference to the accompanying drawing which illustrates a non-restricting embodiment of the invention partially schematically. In the drawings: Figure 1 is a schematic side or front view of an apparatus according to the invention particularly intended for treating hoses of woven material with liquid; Figure 2 is an enlarged view of the nucleus of the apparatus illustrated in Fig. 1; Figure 3 is a partial cross-sectional view in larger scale of the contact zone between the pressure rolls of Fig. 2 along the horizontal centre plane, and Figure 4 is a view of a modified embodiment of the invention, corresponding substantially to Fig. 2.

In Fig. 1 the reference 1 identifies an arrangement for treating material webs 2 with liquid, particularly woven material in hose form. The web 2 is passed to a bath 3 in a manner known per se, this bath optionally comprising a plurality of sequentially arranged trays or like devices in which one or more treatment liquids 4 are located, for example for dying the web. The web is guided on guide rollers 5 in a desired manner and, when concerning material in hose or circular form is preferably inflated at a location in the vicinity of the bath into a bladder-like form 6 which is defined at the bottom thereof by lower, laterally located defining rollers or the like 7 and at the top thereof by similar upper rollers 8.The bladder form of the hose-like web can be achieved in a known manner by injecting air into the hose, and serves to straighten out the hose to prevent the formation of folds therein. Under certain circumstances a lateral bladder 9 can be formed above the upper defining rolls or the like 8, for example by ensuring that the two lastmentioned rolls do not lie firmly against the other, and allowing the air in the bladder 6 to rise. The web 2 is then passed between two mutually abutting and counter rotating pressure rolls 10 which, particularly when made from a resilient material, such as rubber or plastics, for example, are preferably of camber or crown design.

Subsequently to passing through the pressure rolls, the web is led to a reeling roll 1 2 in a receiving station 1 3 over a guide or deflecting roll 11.

As will be seen from Fig. 2, the pressure rolls according to the invention are provided with a treatment web, a treatment covering or the like 14, which extends substantially along the whole active length of the respective rolls around the periphery thereof. This roll covering comprises a porous material, and in particular foamed plastics material having a thickness of 3-30 mm, preferably 10-15 mm.

This covering or the like has good elastic properties which are expressed, inter alia, in the fact that when deformed, for example, compressed, it will return to its original shape without appreciable delay. In the Fig. 2 embodiment, the roll covering 14 or the like is tightly pressed around the pressure rolls 1 0.

This is not absolutely necessary, however, and it is quite possible for a significant clearance to exist between the coverings and their respective rolls, which results, for example in the covering bulging outwardly to some extent, which results in turn in the covering coming into early contact with the web 2 in the infeed zone 23.

A further alternative is illustrated in Fig. 4, in which the roll covering or the like 14' is much longer than the peripheral measurement of the pressure rolls 10, and in which guide rollers 1 5 are provided, these rollers 1 5 together with the pressure rolls 10 guiding the covering or the like 14' in a desired manner, for example to form triangles with the apices of the triangles facing one another with the pressure rolls 10 located in the mutually adjacent apices of said triangles, while the respective guide roller pairs 1 5 form mutually parallel treatment web sections.This design enables the treatment webs or covering or the like to be exchanged in a more ready and simple fashion, while, at the same time, permitting the treatment webs to be guided in different ways and obtain a longer activating path in the peripheral direction, as will be discussed in more detail hereinafter.

The roll coverings or the like 1 4 or treatment webs 14' are pressed together in a contact zone 22 located between the pressure rolls 10 as shown in larger scale in Fig. 3, whereupon the material web 2 passing between said rolls is also compressed. As is clearly shown in Fig. 2, the contact zone has a relatively long total length, for example in relation to the peripheral extension of the pressure rolls, due to the relatively thick and elastically compressible coverings or the like 14 and 14' respectively, the length of the total contact zone lying between 2% and 25%, particularly 15%. This shall be compared with the mathematical value 0 in the case of non-elastic pressure rolls.The length of the contact zone when seen in the throughpassing direction, however, is also relatively insignificant in the case of elastic pressure rolls, wherewith the following scientific observation should be observed: Known pressure rolls used in the present context, whether elastic or non-elastic, are not of porous design, so that the material web saturated in treatment liquid and passing through the contact zone at high speed is treated in almost an explosive manner. In this regard, there is created within the extremely short contact zone extremely high pressures which force from the web a greater part of the liquid contained therein and which can cause webs of certain material to be damaged.A given residual quantity of liquid remains in the material web, particularly between the two sides of hose-like goods, wherewith it can be assumed that this residual liquid remaining in the edge regions between the two sides of the hose will be pressed outwardly under high pressure, since there must naturally remain externally of the edges a free space into which the liquid pressed from the material web can enter. In the case of a number of types of material the main reason can be found herein as to why the material is miscoloured at just the edge regions thereof. The residual liquid may namely either entrain therewith adhered dye particles, so as to result in a light-coloured stripe, or in the case of certain liquids may promote a columning process, such that a minor quantity of dye-containing residual liquid leaves the material hose while the dye remains in higher concentrations so as to miscolour the material, in the form of darkcoloured stripes therealong.

These miscolouring conditions are prevented by means of a treatment web, treatment covering or the like according to the invention, wherewith the following advantageous working methods come into effect: The material web 2, and in particular when inflated to form a hose bladder 6 or 9, will come into contact with the covering or the like 14 and the treatment web 14' on the two pressure rolls in the infeed zone 23 long before it reaches the contact zone 22. As beforementioned, the covering is porous, and as a result hereof, advantageously exhibits an uneven or roughened surface. This can enhance the surface engagement of the material web with the roll covering, so as to avoid undesirable relative displacements, and therewith the formation of folds, to a very large extent.The porous covering, however, is primarily intended to enable the treatment liquid present in the material web and adhering thereto to be transferred in an advantageous manner; more specifically the porous, uneven and rough structure of the covering causes corresponding roughening of the material web resulting in a decisive and uniform departure of liquid to both sides.

At the same time as the material web is compressed in an irregular fashion and obtains an uneven rough surface the liquid contained in the material web is displaced towards both sides thereof and into the engaging covering, wherewith partly air and partly liquid is also displaced transversely through the material web towards both sides thereof.

This is effected by the fact that the pressure rolls as such are sealed-off so as to prevent the ingress or egress of gas or liquid. On the other hand, the covering approaching the contact zone is filled with air for example, which is pressed out through the material web as the covering becomes increasingly compressed, so as to create within the whole of the contact zone an advantageous, uniformly distributed and intensive final treatment phase in which harmful, extreme pressures are totally avoided. It can also be mentioned in this respect that the porous covering which is constantly at least partially filled with air is capable of compressing the gas portion to a fraction of its normal pressure volume and instead leave room for the penetrating liquid, which is afforded sufficient room and time as a result of the long contact zone.Thus, no regions of extreme pressure and the like will occur anywhere in the material web, not even in the edge zones of a hose-shaped material web, and all miscolouring of the web is totally excluded as a result of the apparatus and method according to the invention, such miscolouring being unavoidable with hitherto known apparatus and methods.

It is not solely the contact zone and the infeed zone which are of significance in the present context, but also the outlet zone 24 on the deflecting side of the pressure rolls 1 0.

In this region the covering according to the invention immediately expands as a result of its aforedescribed properties and creates therewith on both sides of the material web in the vicinity of the contact core zone areas of subpressure as a result of which residual liquid and residual air are drawn by suction from the material web and through the same, so as to cause an extremely advantageous partial drying of the material web in this region.

In certain cases it may be highly advantageous, as a supplementary treatment step, to saturate the treatment web or the like 1 4 and 14' respectively with treatment liquid taken from the bath 3, through which the material web has previously passed, with the aid of a pump 1 7 and a conduit 16, and applied to at least one covering via spray nozzles 1 8 in spray zones 19, more specifically at an arbitrarily selected site. Alternatively, a liquid other than the liquid in the bath 3 can be supplied. If the roll covering or treatment web is to be heavily saturated with liquid, the spray zone or zones 1 9 are suitably placed in the proximity of the outlet zone 24.

so that the extended coverings absorb liquid.

In extreme cases the outlet zone 24 may be filled, completely or partially, with treatment liquid. In the majority of cases, however, at least small air cavities should be allowed to remain in the roll covering or treatment web, in order to allow the described advantageous effects afforded by the invention to take place.

An advantageous effect according to the invention can also be obtained, however, with heavily saturated coverings, since in such cases the liquid acts as a smoothing pressure cushion over the major part of the total length of the contact zone. In this respect, attention can be paid under certain circumstances to the speed of the material web and the centre distance between the pressure rolls 10 on a centre plane 21 between the arrows 20 shown in Fig. 2, and a corresponding adjustment made to said speed and said centre distance.

Instead of spraying liquid onto the roll covering or treatment web, it is also possible to apply thereto a gas and/or powderous substance or like substances, wherewith a gaseous treatment agent is advantageously introduced into the outlet zone 24 so as to be absorbed by the extending or expanding porous roll coverings or treatment webs and is intensively deposited thereby onto the passing material web within the infeed zone 23 and the contact zone 22.

The aforedescribed embodiments illustrated in the accompanying drawings shall only be considered to represent non-restrictive embodiments which can be modified and enlarged upon within the scope of the concept of the invention. In addition to the aforedescribed dying process other preferred processes in which the present invention can be applied inciude bleaching and leaching treatment processes.

The roll covering 14, 14' may be provided in two or more layers, of which at least two having different elastic properties. Preferably the outer layer being more elastic than the inner one or one of the inner ones. Furthermore, the covering must not necessaryly consist of porous material. Instead, non-porous rubber and/or plastic material may be provided for at least one of said layers or a single layer covering.

Claims

1. A method for treating material webs with liquid, particularly woven material in hose form, in which the material web is brought into contact with a liquid which is substantially removed from and pressed out of the web exclusively with the aid of pressure rolls, characterized in that the material web (2) is acted upon in the pressure roll zone (22, 23, 24) preferably on both sides by a porous, elastic and heavily deformable treatment web or the like (14 and 14' respectively); and in that the material web is activated by said treatment web or the like by supplying to the material web and/or removing therefrom gaseous and/or liquid and/or particulate media.

2. A method according to Claim 1, characterized in that at least one treatment web or the like (14 and 14' respectively) is supplied with at least one gaseous and/or liquid and/ or particulate further treatment medium.

3. A method according to Claim 2, characterized in that the further treatment media or at least one of the further treatment media is, or are, supplied in the region of the outlet zone (24) of the pressure rolls (10) prior to complete expansion of the respective treatment coverings (14;14')

4. A method according to Claim 1, in which a hoselike material web is to be treated, characterized in that the material web (2) is inflated, more specifically inflated to form a bladder (6) or a lateral bladder (9), and passed to the treatment web or webs or the like (14;14').

5. Apparatus for carrying out the method according to Claim 1 comprising guide means (5) for guiding a material web (2), particularly a web of woven material in hose form; liquid supply means (4), particularly one or more baths (3) for supplying liquid to the material web (2); and pressure rolls (10) located in the proximity of said liquid contact zone forwardly in the direction of movement of the material web, said rolls being intended for re-pressing and pressing from the material web (2) a substantial part of the liquid adhering thereto, characterized in that arranged within the roll pressing zone (22,23,24) preferably on both sides of the material web (2) is a peripherally extending endless, porous, elastic, heavily deformable treatment web or the like (14;;14') arranged to activate the material web (2) by supplying and/or removing gaseous and/or liquid and/or particulate media respectively to and from the material web.

6. Apparatus according to Claim 5, characterized in that the treatment web or the like (14; 14') comprises foamed plastics material and has a thickness of 3-30 mm, preferably 10-15 mm.

7. Apparatus according to Claim 5, characterized in that the treatment web or the like (14; 14') extends around an associated pressure roll (10) in the peripheral direction thereof without any clearance therebetween.

8. Apparatus according to Claim 5, characterized in that the treatment web or the like (14; 14') extends around an associated pressure roll (10) with a considerable clearance therebetween in the peripheral direction of said roll and in particular under the guiding influence of deflecting rolls (15), which together with the pressure rolls (10) guide the treatment web (14') in a desired manner, particularly in the form of a triangle, of which two angles of the triangle are formed by a respective deflecting roll (15) and the third by the associated pressure roll (10).

9. Apparatus according to Claim 5, characterized in that the roll covering is provided in two or more layers, of which at least two having different elastic properties.

10. Apparatus according to Claim 5, characterized in that at least part of the roll covering is constituted of non-porous material, particularly rubber or plastic material.

11. A method for treating material webs with liquid substantially as hereinbefore described with reference to the accompanying drawings.

1 2. Apparatus for treating material webs with liquid substantially as hereinbefore described with reference to the accompanying drawings.