DE3103359A1 - Process and apparatus for the uniform application of a small quantity of a treatment agent in foam form - Google Patents

Abstract

Process and apparatus for the uniform application of a small quantity of a treatment agent to the surface of a web of a material to be treated, in which the treatment agent is first applied uniformly in a liquid preparation in the form of a foam to a moving screen band and a screen band, after it has covered a distance beyond the application point, is brought together over its surface with the web for the purpose of transferring the treatment agent. <IMAGE>

Description

PATENT LAWYERS '4 D V SS ELD OB F, "3 <3cfei CBO <J! Ol y i < 1

NC. AVALTER KUBORN Dr.P./Sch HYS. DR. PETER PALGEN - »5T- ί263ί DUSSELDORF ^l '

^r STRASSE 2 TELEPHONE 832727

TILL DÜSSELDORF NO. 1014 463 BANK AC. DUSSELDORF 2919207 CORNER ACCOUNT: COLOGNE 115211.504

Eduard Küsters
in 4150 Krefeld

Method and apparatus for uniformly applying a small amount of a treating agent in foam form

The invention relates to a method of the type corresponding to the preamble of claim 1 and a corresponding device.

In the subject of the earlier patent application P 29 35 413.0 by the same applicant, the foam is applied against a rotating drum and doctored to a uniform height. The uniform foam layer runs over a certain angular range with the drum before the web to be treated with the treatment agent runs onto the circumference of the drum and encloses the foam layer between itself and the drum surface so that the foam liquid can penetrate the surface of the goods. the "Hi fsträger" is -ler so in this case ones .SekLor closed drum surface, the zvljchen J & x uxe foam layer abstreichenden squeegee and. "^ r · ^parking: ij £ ed. \" cn Jer track is located.

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It has been shown that application quantities of up to about 20 g per square meter of web surface can be applied with a device of the known type. In trying to drive even lower amounts, the uniformity of the transferred to the carrier foam 'layer is no longer guaranteed.

In some cases, however, it is desirable to apply even lower amounts per unit area of the web. The invention has for its object to provide a method and a device with which the Application of particularly small amounts of a foam containing a treatment agent per unit area ; a train is possible.

; This task is indicated by the in claim 1

: bene invention solved.

Instead of the closed drum surface, the auxiliary carrier is a sieve belt, which has a large number of Has perforations into which the foam can penetrate immediately after being applied to the sieve belt. this is caused by the capillarity in the many gaps in the sieve belt as well as by the diverse surface forces that are more noticeable than with a smooth surface, because a sieve belt is one larger active surface than a smooth Troranel circumference .; having. The sieve belt acts like a kind of reinforcement that

holds the thin foam layer in its even distribution ΐ and prevents it from tearing open. In this way

; ^; a foam layer with a much smaller area can

[weight must be maintained evenly.

ti * "

! The use of a sieve belt when applying foam

ί is known per se from US Pat. No. 3,084,661.

Here, the web is guided between two sieve belts and the foam is passed directly through one sieve belt

transferred to the railway. Here, the web is in connection with the foam supply, which is the case with the invention just to be avoided.

ί The measure according to claim 2 ensures that

a complete "filling" of the main web in the short one

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can take place at the time available for this.

At least some of the foam or the liquid that forms it goes through just touching it with the train on this over, especially if the train is porous and capillary forces occur. However, in order to remove the foam as completely as possible from the sieve belt on the To bring the train and also to increase the working speed, the measure according to claim 3 is recommended, according to which, for example, an overpressure is applied to the screen belt side or, in the case of porous webs, from the web side can be sucked.

According to claims 4 to 7, the invention is also embodied in a device.

In order to be able to put the foam under a certain pressure when it is applied to the sieve belt, we recommend a design of the foam application device according to claim 8. The foam feed chamber may only be in the wraparound area, in which the screen belt is covered on the back by the closed application roller, be open, because otherwise the foam will simply be blown through the sieve belt if there is overpressure on the front would.

To adjust the amount of foam transferred to the sieve belt or the height of the foam generated on the sieve belt Foam layer, the configuration according to claim 9 is recommended.

The feature of claim 10 is used to the foam when it the foam feed channel against the sieve belt flows through to compress something. As has been shown, this results in additional homogenization of the foam. This effect is known from DE-OS 29 15 289 per se.

When the main web *. .cn deferment of the wrap angle, the application roller others w ^r, the foam is pulled over by the adhesion of the applicator roll something facing to Derder applicator roll side of the wire. Since the sieve belt runs endlessly in a closed path, the must for spatial reasons with the

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Treatment agent to be provided path from the other Side to be brought up to the sieve belt. For the process of transferring the foam from the sieve belt

on the web it would therefore be more beneficial if the main amount of the foam on the side of the screen belt facing the web to be found. In order to achieve this, the measure according to claim 11 is expedient. "._ ■" ..

The underlying idea can be further developed according to claim 12.

This will on the application roller about haf i s "detected retarded foam and immediately pressed back into the screen belt. In addition, a certain slight excess pressure builds up in the closed chamber in the flow gusset on, sufficient to the foam from the surface facing the applicator roll side of the sieve belt over to the other side.

The invention is not limited to that described above Foam application device bound. In claim 13 is a further embodiment of a foam application device indicated, which can also be used for the "purposes of the invention.

The supporting sieve belt according to claim 14 is important in that it supports the web in the transfer area and holds it between two sieve belts. This is particularly important in the case of webs made from nonwovens that have not yet been or not yet completely produced. The suction takes place through the supporting sieve belt, so that the possibly sensitive material web is not stressed. This is known per se from .US-PS 3 Ö84 661. · *. Instead of the supporting sieve belt, a sieve drum with a suction slot nozzle arranged in it can also be provided according to claim 15, which in some cases reduces the structural effort V / V ^ "^;;;^;

. - An important feature is that in claim 16 again, given distance. This serves on the one hand to the web in certain cases to protect, for example if these are made of a not yet fully consolidated fleece! exists, which is mixed up by a sieve belt lying directly on top of it or when the sieve belt is removed could be torn apart. In particular, however, an independence of the forward speed of the screen belt from the forward speed of the web is created by the distance, through which the screen belt can run slower than the web, whereby the the amount of foam contained therein over a greater "length of the Web is distributed, or faster to achieve the opposite effect.

-: ■. In this way, minimal application quantities can be achieved without the uniformity of the distribution being impaired by tearing the foam film or the like. .

In the drawing, exemplary embodiments are more according to the invention Devices shown.

1 shows a schematic side view of a foam application device according to the invention. in vertical longitudinal section;

2 shows the foam application device drawn out on an enlarged scale; "-..-. Fig. 3 shows a view of the foam application device according to FIG. 2 from the right;

4 shows a system with two foam application devices according to claim 1, by means of which a web can be provided with foam on both sides; # _t

Fig. 5 shows a cross section through an alternative embodiment of the foam application device.

According to FIG. 1, the web 1 of the material to be treated is guided in the foam application device designated as a whole by 10. An upper sieve belt 3, which serves to transfer the foam, and a lower sieve belt O , which only has a supporting function, are provided. Both sieve

O bands 3, 4 run around endlessly in such a way that they are in the ^, the area 40 facing the web 1 in the same direction as this

S - For the upper main web 3 is one as a whole with

i- 5 designated foam application device is provided, which

■ - an application roller 6 and a foam feed chamber 7 around

; summarizes and will be described in detail with reference to FIG

I will.

_ä The application roller 6 forms with the screen belt 3 one

. Drainage gusset 8. In the drainage gusset 8 is a doctor blade 9

; arranged with an edge at 11 on the sieve belt 3

j and with the other edge 12 on the circumference of the application roller 6

is present. At both ends is the one in the drainage gusset 8 formed chamber in a manner not shown / opened. Foam applied to the sieve belt is through the edge 11 of the doctor blade 9 towards the web 1

^: turned side pushed through. It will also take part in the application

roller 6 wiped off any remaining foam through the edge 12 of the squeegee 9 and also back onto the Sieve belt 3 applied.

On the line 13, the screen belt 3 provided with the foam runs freely, i.e. without the web 1 or to be connected to the foam supply. This free running path is for the evenness of the foam application essential. If the web 1 came into direct contact with the entire foam supply, then would

.. due to the always existing differences in the suction

: ability of the web and also in the foam reserve itself

: the web is at different points on its surface

To a certain extent appropriate different amounts of foam per unit area. Due to the free travel distance 13, however, is any compound of the web inhibited to a greater amount of foam and the web I will only accurately

j, the defined and in particular existing in the sieve belt 3

ι Allocated an even amount of foam.

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After covering the free running distance 13, the screen belt 3 is level with the pair of rollers 14 with the Lane 1 brought together. By setting the roller spacing accordingly, it can be achieved that the The sieve belt 3 rests directly on the web 1 or maintains a small distance. In the latter case, the sieve belt 3 run at a different, in particular slower speed than the sieve belt 4 or the web 1, so that the amount of foam located on a length of the screen belt is on a larger length of the web 1 and even smaller amounts can be applied to the web 1. Through mere contact some of the foam is already transferring to web 1. To support the transition, the nip roller | pair 14 downstream on the back of the web 1 a suction nozzle 15 extending across the width of the web 1 be present, the effect of which in some cases is indicated by a dashed line above web 1 the suction nozzle 15 arranged opposite the blowing nozzle 16 can be supported.

The sieve belt 3 runs a short distance together with the web 1, whereby it faces this over the whole area. The screen belt 3 is guided away from the web 1 at the deflection roller 17, as is the supporting screen belt 4 on the deflection roller 18. The screen belt 3 then passes another suction nozzle 19, which is approximately the distance remaining foam and liquid residue from the sieve belt is used and then returns to the foam application device 4, where it is reloaded with foam.

It is practically important that the web 1 is supported on the screen belt 4 in the transfer area. It In this way, you can also use sensitive materials such as thin fleeces, which only have a low tensile strength have to be processed. Mechanical stress on web 1 in the transmission area

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does not take place because it is supported over the entire area by the sieve belt 4.

According to FIG. 2, the foam application device comprises an application roll 6, which extends over the width of the sieve belt 3 extends and has a closed surface. The screen belt 3 lies in a looping area 20 on the surface of the application roller 6. The foam application chamber 7 also extends over the Width of the screen belt 3 and comprises a box-shaped sheet metal housing 21, in which by a partition 22 the actual foam feed chamber 7 is divided in such a way that its cross section extends from the mouth of the Foam feed line 23 tapers up to the side 24 which is open towards the screen belt 3. When flowing through the Foam feed chamber 7 results in a certain compression and homogenization of the foam.

The open side 24 of the foam feed chamber 7 lies in the wrapping area 20 against the outside of the Main belt 3. In the area of the open side 24, the screen belt 3 is on the back through the closed Surface of the application roller 6 covered, so that in the foam feed chamber 7 a certain overpressure can be adjusted.

According to FIG. 2, the foam feed chamber 7 is delimited at the bottom by a doctor blade 25 which is placed on the floor 26 of the housing 21 and supported over a plurality of spindle drives 27 distributed over the width of the sieve belt in the sense of the arrow 28 can be shifted. As a result, the gap 29 can be precisely adjusted, whereby the Thickness of the foam layer transferred to the sieve belt 3 and thus also the amount of foam or the amount of treatment agent per unit area are determined.

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4 shows a system for the simultaneous double-sided application of a treatment agent in foam form to a web 1. The upper left area corresponds to the illustration in FIG. 1 and in this respect also bears the same reference numbers. However, the screen belt 3 ¹ is not immediately fed back to the foam application device 5, as in FIG. 1, after having covered the application path and passing the deflection roller 17, but at the same time serves as a support belt for the foam application device, which applies foam to the underside of the web 1 . The elements of this foam application device are identified with primed numbers. The lower sieve belt 4 ¹ acts as a transfer sieve belt for the foam application device 5 'and as a support sieve belt for the foam application device 5.

In Fig. 5 is an alternative foam applicator 30 shown, which consists of a closed housing 31, the opposite to each other Sides locks 32,33, which extend over the width of the sieve belt 3 and the passage allow the sieve belt 3 under a certain seal. The foam is delivered through the foam supply lines 34,35 and fills the housing 31 substantially. Even with the foam application device 30, in Inside the housing 31, a certain upper pressure is maintained to allow the foam to pass into the To promote sieve belt 3 and accelerate. i

In Fig. 6 a device designated as a whole with 50 is shown, which in its upper part corresponds entirely to the device according to FIG. The lower, supporting sieve bar: ^ the F ⁴ ".:. 6 is each h with Hr - r extending over the width of the web, revolving around an axis directed transversely to the web in the specified sense, from below on the web between the Deflection rollers 14 and the screen belt 3 adjacent screen drum 54 is provided in which a suction pipe 56 is arranged, which on his

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the side facing the web 1 forms a suction slot nozzle 55 which extends over the width of the web 1 and through 6 only schematically indicated seals 57 is sealed at least to such an extent that in the event of a negative pressure In the suction pipe 56, the air essentially enters through the suction slot nozzle 55. The train is in that Embodiment supported on support rollers 53. The foam transported by the sieve belt 3 is on the suction slot nozzle 55 is transferred into the web 1.

The embodiment shown in Fig. 6 requires a certain inherent tensile strength of the web 1, because the web 1 by pulling on itself over aie Slotted suction nozzle 55 is transported. The embodiment according to FIG. 1 with the screen belt 4 is technically something more expensive, but has the advantage that no forces are exerted on the track 1 and also very loose tracks, for example fleeces, which can be processed on the lower sieve belt 4 before entering the device 10 can be stored.

Thin woven fabrics, lightweight nonwovens, paper and the like come into consideration as the material for the web 1. at the processing of cotton fabric with a surface

weights of around 30 g / m 2 could be achieved at working speeds of 50 and 100 m per minute and suction from below (suction nozzle 15 in Fig. 1) application quantities of

Achieve 30 to 35%, with the surface coverage, as was readily apparent from the staining, completely was even. The particular advantage is that this area occupancy can be achieved in a defined manner without that the web of material has to be soaked with a large amount of liquid and then squeezed off. That Quite apart from that, squeezing off allows a much less precise adjustment of the amount of liquid applied the associated stress on the goods.

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The amount applied in these tests was about 10 to 12 g / m ² .

Another example is the impregnation of a

pre-bonded spunbonded polyester with a

Weight per unit area of a little over 10g / m. It became a

Latex binder used, which was diluted 1: 4 with water and provided with a foaming agent 1. These Mixture was foamed to a degree of foaming of 1: and then applied to the spunbonded nonwoven. There the mixture was colored, the uniformity of the application was visually easily recognizable. There were Order quantities of 30 to 40% evenly achieved what

an area covering with the treatment liquid text

2
from about 4 to 5 g / m 2. In these attempts

if the upper sieve belt (3 in Fig. 1) was partially allowed to run slower than the lower sieve belt (4), see above that the amount of foam contained in the sieve belt 3 was distributed over a larger surface of the web 1.

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Claims (17)

Claims 1st A method for uniformly applying a small amount of a treatment agent to the surface of a web of an item to be treated, in which the treatment agent in a liquid preparation in the form of a foam is initially applied evenly to a moving auxiliary carrier and the auxiliary carrier after it has traveled a distance from the application site has, for the transfer of the treatment agent, is brought together flatly with the web, characterized in that the foam is applied to a sieve belt as an auxiliary carrier. 2. The method according to claim 2, characterized in that that when the foam is applied to the sieve belt, it is pressed into the S:> i belt under pressure. 3.. The method according to Ansp_ach i oi ^ er 2, characterized in that that the transition of the upper space from the main belt on di-orbit by means of a pressure difference will. BATH ORIGINAL EPO - COPY 4. Apparatus for performing the method according to claims 1 to 3, with one with the Web moving along with this auxiliary carrier in width, with an application device, by means of whose a uniform foam layer can be applied to the auxiliary carrier, and with a web guide, by means of the web of which is located at a distance behind the application point in the direction of movement of the auxiliary carrier Place can be brought together flatly with the auxiliary carrier carrying the foam layer, thereby f indicates that the auxiliary carrier is designed as an endless circulating sieve belt (3, -3 ', 4'). 5. Apparatus according to claim ■ '*, characterized in that at one of the point of bringing together downstream point at which the web (1) and the screen belt (3; 3', 4 ') are still guided flat opposite one another, a device to generate a higher pressure on the side of the screen belt (3; 3 ', 4'). 6. Apparatus according to claim 5, characterized in that that on the side facing away from the sieve belt (3; 3 ', 4') a suction device extending over the width of the web (1) (15.15 ') is set. 7. Apparatus according to claim 5 or 6, characterized in that on the side of the screen belt (3; provided chamber _(16); 3 ', a 4'j extending over the width of the web (1) overpressure. 8. Device according to one of claims 4 to 7, characterized in that the foam application device (5,5 ') one of the sieve belt (3; 3', 4 ') wrapped around, application roller having a closed surface (6) and one. Against the screen belt (3; 3 ', 4') in the looping area (20) on the outside lying against the sieve belt (3; 3 *, 4 ') open, otherwise except for the foam feed line (23) includes closed foam feed chamber (7). bad original EPO - COPY --ä * ^Ί 9. Apparatus according to claim 8, characterized in that that the foam feed karamer (7) on the discharge side through a directed against the sieve belt (3; 3 ', 4') Squeegee (25) is completed, which is adjustable to produce a variable gap (29). 10. Apparatus according to claim 8 or 9, characterized in that the foam feed chimney (7) has a cross-section tapering towards the open side (24) facing ^{the sieve belt (373 ', 4 1 J facing).} 11. Device according to one of claims 8 to 10, characterized in that the application roller (6) in the direction of movement downstream and before the web (1) comes into contact with the sieve belt (3; 3 ', 4') from the side facing away from the web (1) against the screen belt (3; 3 ', 4'), the doctor blade (9) is provided. 12. The device according to claim 11, characterized in that the doctor blade (9) is on the drain side of the screen belt (3; 3 ', 4') from the application roller (6) formed gusset (8) covered and at the same time rests with the other edge (12) on the application roller (S) and the gusset (8) formed is closed at the ends. 13. Device according to one of claims 4 to 7, characterized in that the foam application device (30) has an opposing lock (32, 33) for the passage of the sieve belt (3) and at least one feed line (34, 35) for the foam, otherwise closed chamber extending over the width of the screen belt (3). 14. Device κ h ainem of claims 4 to 13, characterized in that on the '^ m screen belt (3; 3', 4 'remote side of the web (1) in the area in which the screen belt (3; 3 ', 4') and web (1) opposite to each other, a web (1) supportive, endless mitvorlaufendes with the web (1) supporting wire belt (4; 4 ', 3') is ^provided!.! EPO - COPY l V 15. Device according to one of claims 4 to 13, characterized in that on the screen belt (3) remote side of the web (1) in the area in which the screen belt (3) and web (1) are opposite one another, a rotating sieve drum resting against the web (1) with one inside the sieve drum in the contact area the web (1) directed against the web over the width of the web (1) extending, at the mouth edge is provided all around substantially sealed suction slot. 16. Device according to one of claims 4 to 15, characterized in that the sieve belt (3; 3 ', 4') or the sieve drum of the web (1) are opposite in the transfer area at a small distance. 17. The device according to claim 15, characterized in that that the sieve belt (3) can be driven at a different speed than the supporting sieve belt (4) or the sieve drum. EPO - COPY