EP0794011B1 - Device and process for applying a liquid resin on a moving web - Google Patents

Abstract

The system for coating a liquid resin onto a moving belt (B) comprises a pourer (2') formed by the bottom of a liquid resin gravity supply tank (13'). The bottom slopes close to the belt. A support wall (6') acts as a rough calibrator and spreader of a thick resin layer on the belt. The wall supports an inclined section (15) on its upper edge (14) which extends across the belt width. The upper edge (17) under the inclined section follows the belt and precisely calibrates the thick resin layer to a predetermined thickness and recover the excess resin. The recovered resin flows freely along the inclined wall to reach its lower edge (16) and enter the tank. The recovered resin causes turbulence in the tank and homogenises the liquid contained in it.

Description

The invention relates to a device for coating liquid resin on a strip running vertically.

Reference will be made to FIG. 1 for the description of the art prior to the invention.

To coat a strip B, in particular a metal strip, with a layer of liquid resin with a thickness of, for example, between 50 and 300 μm, it is known practice to apply a coating device 1 against the face to be coated. scrolling this strip B vertically from bottom to top as shown in Figure 1.

• des moyens d'application de résine, comme un bec verseur 2, pour distribuer la résine sur toute la largeur de la bande à enduire ;
• des moyens de calibrage grossier 3 pour étaler une couche épaisse de résine sur la bande ;
• des moyens de calibrage précis, comme une barre de calibrage fin 4, pour calibrer la couche épaisse de résine au niveau d'une couche 10 d'épaisseur prédéterminée et pour éliminer la quantité de résine appliquée en excès par rapport à ladite épaisseur.

The coating device 1 used for this application successively comprises along the path of the strip:

• resin application means, such as a spout 2, for distributing the resin over the entire width of the strip to be coated;
• coarse calibration means 3 for spreading a thick layer of resin on the strip;
• precise calibration means, such as a fine calibration bar 4, for calibrating the thick layer of resin at the level of a layer 10 of predetermined thickness and for eliminating the quantity of resin applied in excess relative to said thickness.

According to the representation of FIG. 1, the coarse calibration means 3 comprise a support plate 6 supporting a coarse calibration rule 5 at the level of a lower edge 18 inclined towards the strip; this coarse calibration rule 5 is adjustable in position relative to the strip B to be coated according to the thickness of resin which it is desired to spread on the strip at this level.

On the face opposite that of the coating means 1, the strip B comes to bear in particular against rollers 8, 9 respectively at the level of the pouring spout 2 and of the fine calibration bar 4.

• une zone inférieure où la bande est nue, située sous le bec verseur 2.
• une première zone au niveau du bec verseur 2 où la bande vient au contact de la résine liquide à enduire ;
• une deuxième zone située entre la règle de calibrage grossier 5 et la barre de calibrage fin 4, où la bande est revêtue d'une couche épaisse de résine ;
• une zone supérieure située au dessus de la barre de calibrage fin 4, où la bande est revêtue de la couche de résine 10 d'épaisseur prédéterminée.

Thus, along the path of the rising band B, there are, from bottom to top, four zones

• a lower area where the strip is bare, located under the spout 2.
• a first zone at the level of the pouring spout 2 where the strip comes into contact with the liquid resin to be coated;
• a second zone located between the coarse sizing rule 5 and the fine sizing bar 4, where the strip is coated with a thick layer of resin;
• an upper zone situated above the fine calibration bar 4, where the strip is coated with the resin layer 10 of predetermined thickness.

The coating device 1 is also provided with a reservoir 13 for gravity supply of the distribution means (pouring spout 2).

The walls of this supply tank 13 are formed by a cover 11 enveloping the coarse calibration means 3 as close as possible to the strip B and by the support plate 6 approximately parallel to the strip B.

The support plate 6 therefore also serves to isolate the moving strip from the resin contained in the reservoir 13.

The bottom of the reservoir 13 is inclined and opens directly into the pouring spout 2 which is used to apply the resin to the strip.

The geometry of the cover 11 is adapted to create a reservoir 13 of sufficient volume to keep the application means in charge - here the pouring spout 2 - in a constant manner and over the entire width of the strip.

This reservoir 13 is itself supplied via conduits 12A, 12B by supply means - not shown here - adapted in a manner known per se to maintain in this reservoir 13 liquid resin at a filling level approximately constant so as to keep the spout 2 under an approximately constant load.

This reservoir 13 is thus normally open upwards, as shown in FIG. 1.

The coating device 1 also includes a frame 19 for supporting the components described above.

Coating devices of the type which have just been described have a drawback in the case of coating of liquid resins loaded with solid particles in suspension, in particular when these particles are in unstable suspension in the resin.

These particles may for example be pigments.

Indeed, in this case, these solid particles tend to settle in the bottom of the tank 13, in particular near the means for applying resin to the strip.

As a result, the resin layer 10 deposited on the strip at the outlet of the coating device 1 is likely to no longer be homogeneous, in particular due to poor distribution of the solid particles in said layer.

The object of the invention is to improve the aforementioned coating device intended to ensure a uniform deposition of resin on a strip even if said resin contains solid particles in unstable suspension.

• des moyens pour mettre en contact la résine avec la bande tout en la distribuant sur toute sa largeur ;
• des moyens de régulation de débit d'application de résine sur la bande,
• des moyens de calibrage précis formés par une lame flexible.

Patent application FR 2 545 736 describes a coating device which successively comprises, along the path of the strip to be coated:

• means for bringing the resin into contact with the strip while distributing it over its entire width;
• means for regulating the rate of application of resin to the strip,
• precise calibration means formed by a flexible blade.

As illustrated in FIG. 1 of this document, the precise calibration means are used to calibrate the layer to a predetermined thickness without significantly eliminating resin there, since, upstream, the flow regulator is adjusted so as not to maintain on the strip approximately as the amount of resin required for the predetermined thickness to be applied.

And it is because only a small amount of resin escapes from the contact zone that it is not necessary to provide, as in the invention, means for recycling the excess resin (page 4, lines 16 to 22).

Indeed, the preamble of this document (page 1, lines 31 to 35) has the disadvantages of devices in which relatively large quantities of excess resin must be removed from the strip (as in the device according to the invention), know in particular the need to provide a complex recycling circuit for the resin applied in excess.

The essential function of the flow regulator, given its particular geometry, is here to reduce the risk of bar formation (page 4, line 35 to page 5, line 1).

The invention provides simple means for recycling the resin applied in excess and proposes to use these means to ensure a uniform deposition of resin on a strip even if said resin contains solid particles in unstable suspension.

• des moyens d'application pour distribuer la résine sur toute la largeur de la bande à enduire ;
• des moyens de calibrage grossier pour étaler une couche épaisse de résine sur la bande ;
• des moyens de calibrage précis pour calibrer ladite couche épaisse de résine au niveau d'une couche d'épaisseur prédéterminée sensiblement inférieure à celle de ladite couche épaisse et pour éliminer la quantité de résine appliquée en excès par rapport à ladite épaisseur prédéterminée ;
• un réservoir d'alimentation par gravité desdits moyens d'application,

caractérisé en ce qu'il comprend en outre :

• des moyens de recueil de ladite quantité de résine appliquée en excès qui est éliminée par lesdits moyens de calibrage précis,
• et des moyens de redistribution de ladite quantité de résine recueillie vers ledit réservoir, ces moyens étant adaptés pour créer dans ledit réservoir des turbulences aptes à réhomogénéiser en permanence la résine liquide contenue dans ledit réservoir.

The subject of the invention is a device for coating liquid resin, in particular containing particles in unstable suspension, on a moving strip, of the type comprising successively along the path of the strip:

• application means for distributing the resin over the entire width of the strip to be coated;
• coarse sizing means for spreading a thick layer of resin on the strip;
• precise calibration means for calibrating said thick layer of resin at a layer of substantially predetermined thickness less than that of said thick layer and to remove the amount of resin applied in excess relative to said predetermined thickness;
• a gravity supply tank for said application means,

characterized in that it further comprises:

• means for collecting said quantity of excess applied resin which is removed by said precise calibration means,
• and means for redistributing said quantity of resin collected towards said tank, these means being adapted to create in said tank turbulence capable of permanently rehomogenizing the liquid resin contained in said tank.

• les moyens de calibrage grossier sont réglés de manière à ce que l'épaisseur de la couche épaisse soit au moins deux fois supérieure à ladite épaisseur prédéterminée.

The invention may also have one or more of the following characteristics:

• the coarse calibration means are adjusted so that the thickness of the thick layer is at least twice greater than said predetermined thickness.

• lesdits moyens de redistribution de la résine en excès sont adaptés pour déverser ladite résine par gravité approximativement au centre dudit réservoir.

In this way, a high flow rate of excess resin recirculation in the tank is ensured, which further improves the rehomogenization of the resin in said tank.

• said means for redistributing the excess resin are adapted to pour said resin by gravity approximately at the center of said reservoir.

• lesdits moyens de recueil et les dits moyens de redistribution sont solidaires des parois dudit réservoir.
• lesdits moyens de recueil et les dits moyens de redistribution sont formés par un pan incliné, dont le bord supérieur vient longer la bande juste en dessous desdits moyens de calibrage précis pour recueillir l'excès de résine se déversant par gravité le long de la bande et dont le bord inférieur surplombe sensiblement le centre dudit réservoir.

The pouring of the resin in the center of the tank makes the recirculation of the excess resin more efficient for rehomogenization.

• said collection means and said redistribution means are integral with the walls of said tank.
• said collection means and said redistribution means are formed by an inclined pan, the upper edge of which comes along the strip just below said precise calibration means to collect the excess resin pouring by gravity along the strip and whose lower edge substantially overhangs the center of said tank.

This recirculation device by inclined pan is, on the one hand simple and economical, on the other hand effective for rehomogenization in particular in that the resin is poured into the center of the tank.

The invention also relates to the use of this resin coating device for coating liquid resin containing solid particles in unstable suspension.

• la figure 1 représente une vue latérale en coupe d'un dispositif d'enduction selon l'art antérieur.
• la figure 2 représente une vue latérale en coupe d'un dispositif d'enduction perfectionné selon un mode privilégié de réalisation de l'invention.
• la figure 3 représente le dispositif selon l'invention en position dite de repos dans un mode particulier de réalisation de l'invention où une partie du dispositif est escamotable.

The invention will be better understood on reading the description which follows, given by way of example, and with reference to the appended figures in which:

• Figure 1 shows a side sectional view of a coating device according to the prior art.
• 2 shows a side sectional view of an improved coating device according to a preferred embodiment of the invention.
• FIG. 3 represents the device according to the invention in the so-called rest position in a particular embodiment of the invention where part of the device is retractable.

• le bec verseur 2' des moyens d'application est formé par le fond du réservoir 13', ledit fond étant ici incliné sans rupture de pente jusqu'au voisinage de la bande B.

Referring to this FIG. 2, according to this preferred embodiment, the coating device 1 ′ according to the invention uses the same components referenced in the same way as the device described in the preamble to the present application, with the difference of than :

• the pouring spout 2 'of the application means is formed by the bottom of the reservoir 13', said bottom being here inclined without breaking the slope to the vicinity of the strip B.

• la plaque support 6' des moyens de calibrage grossier 3' qui forme une paroi du réservoir 13' supporte également par son bord supérieur 14 un pan incliné 15.

Such an arrangement makes it possible to limit the risks of accumulation of solid particles of resin in this part of the tank.

• the support plate 6 'of the coarse calibration means 3' which forms a wall of the reservoir 13 'also supports, by its upper edge 14, an inclined face 15.

The inclined face 15 extends over the entire width of the strip and is dimensioned so that, on the one hand, its upper edge 17 comes along the strip just below the precise calibration means so as to collect the excess resin. pouring by gravity along the strip and so that, on the other hand, its lower edge 16 substantially overhangs the center of the reservoir 13 '.

The support plate 6 'has no "sole" in contact with the resin over its entire height, unlike the flow regulator described in the document FR 2 545 736 previously cited; here, on the contrary, as described in FIG. 2, after the rough calibration, the resin surface remains free over the entire height of the support plate 6 '.

We will now describe the operation of the improved device 1 'according to the invention.

To coat a resin layer of predetermined thickness 10 on the strip B, the procedure is known in itself as with the device 1 of FIG. 1 of the prior art.

Thanks to the improvement according to the invention, the quantity of resin applied in excess relative to a predetermined thickness which is eliminated by the precise calibration means, here the calibration bar 4, flows freely along the strip B against the direction of the scrolling as indicated by the arrow F1 then is collected by the upper edge 17 of the inclined face 15 when it reaches its level.

This upper edge 17 of the inclined face 15 therefore serves here as a means of collecting the quantity of resin applied in excess.

This quantity of resin thus collected then flows freely along the inclined face 15 to reach its lower edge 16.

At this point, the quantity of excess resin is poured approximately in the middle of the reservoir 13 'of resin as indicated by arrow F2.

This lower edge 16 of the inclined face 15 therefore serves here as a means of redistribution of said quantity of resin collected by said collection means.

The excess resin is then returned to the circuit which supplies the application means - pouring spout 2 '.

According to the invention, the pouring of the excess resin into the reservoir 13 ′ causes turbulence capable of permanently rehomogenizing the liquid resin contained in this reservoir.

Thus, especially when the liquid resin contains solid particles in suspension, these particles are constantly stirred by this turbulence, which in particular prevents their possible settling in the bottom of the tank.

Preferably, the coarse calibration means 3 ′ are adjusted so as to deposit a thickness at least twice the predetermined thickness, so as to ensure a high flow rate of excess resin recirculation and sufficient mixing of the particles in the tank. .

It is thus possible, thanks to the invention, to deposit on strips very homogeneous resin layers, in thickness and composition, even when this resin contains solid particles and even when these solid particles tend to settle in the liquid resin. .

Another advantage of the invention is that, thanks to the elimination and redistribution in the reservoir of the excess resin, it is avoided that the resin does not "drip" up to the level of the coarse calibration rule 5 and thus does not disturb the initial spreading of the resin on the strip.

Thanks to this advantage, the uniformity, especially in thickness, of the layer of resin deposited on the strip is further improved.

Without departing from the present invention, any other means of collecting and redistributing the excess resin in the reservoir 13 ′ can be used. to create turbulence in this tank capable of permanently rehomogenizing the liquid resin it contains.

• le réservoir 13' est fermé par un couvercle 20 dont un panneau peut être rabattable.

According to another variant of the invention, said coating device 1 ′ has other differences from the device 1 of the prior art, in particular at the level of the cover 11 ′ which delimits said reservoir 13 ′.

• the reservoir 13 'is closed by a cover 20, a panel of which can be folded down.

• le dispositif d'enduction 1' est escamotable.
• le réservoir 13' peut être mis en rotation autour d'un axe 21 horizontal solidaire du châssis 19 du dispositif d'enduction et positionné au niveau de la partie basse dudit réservoir.

The cover 20 is generally secured to the cover 11 ′, and can be formed by a folded upper edge as shown in FIG. 2.

• the coating device 1 'is retractable.
• the reservoir 13 ′ can be rotated about a horizontal axis 21 secured to the chassis 19 of the coating device and positioned at the level of the lower part of said reservoir.

• le dispositif d'enduction 1' est doté de moyens 7' pour faire pivoter le réservoir 13' d'une position de repos où la plaque 6' formant paroi du réservoir 13' est approximativement horizontale vers une position de travail où cette paroi 6' est verticale et approximativement parallèle à la bande B en défilement.

This rotation of the reservoir 13 'drives the means which are integral with said reservoir, here in particular the coarse calibration means 3', which makes it possible to retract a large part of the coating device 1 'and to release a large part of the band masked by this device.

• the coating device 1 'is provided with means 7' for pivoting the reservoir 13 'from a rest position where the plate 6' forming the wall of the reservoir 13 'is approximately horizontal towards a working position where this wall 6' is vertical and approximately parallel to the moving band B.

The rest position is shown in Figure 3 (arrow F3) and the working position is shown in Figure 2.

Thanks to this variant of the invention, which provides a cover 20 to the reservoir 13 'and the possibility of pivoting the reservoir 13' approximately around its lower edge close to the strip, part of the coating device 1 can be retracted 'without losing resin.

In fact, the resin contained in the reservoir 13 'in the working position remains in the reservoir 13' even if it passes into the rest position.

Another advantage linked to the closure of the reservoir by the cover 20 is that it limits the evaporation of resin during the coating operations, which is also favorable for the homogeneity of the coating.

The coating device according to the invention can also advantageously be translated along the arrow F4 in FIG. 3 to move it away from the strip B.

The possibility of thus easily retracting part of the device 1 'according to the invention advantageously facilitates interventions near the strip, in particular in the event of malfunction of the coating device 1',

This possibility also facilitates the emptying of the device 1 'between two tape coating campaigns and its cleaning.

The device 1 'shown in Figures 2 and 3 also provides a stop 22 integral with the frame 19, to support the reservoir 13' in the rest position.

Claims (6)

1. Device, (1, 1') for coating a liquid resin, especially one containing particles in unstable suspension, on a running strip (B), comprising in succession along the path of the strip:

   - application means for distributing the resin over the entire width of the strip to be coated;

   - coarse gauging means (3, 3') for spreading out a thick layer of resin over the strip;

   - and accurate gauging means (4) for gauging the said thick layer of resin into a layer of predetermined thickness substantially less than that of the said thick layer and for removing the amount of resin applied in excess with respect to the said predetermined thickness;

      and furthermore comprising:

   - a tank (13, 13') for supplying, by gravity, the said application means,

   - means for collecting the said amount of resin applied in excess, which is removed by the said accurate gauging means (4),

   - and means for redistributing the said amount of collected resin into the said tank (13, 13'),

      characterized in that:

   - the said collecting means are suitable for separating the stream of resin applied in excess from the stream of resin corresponding to the said thick layer entrained by the running of the said strip (B),

   - the said coarse gauging means (3') are controlled so that the thickness of the thick layer is at least twice as great as the said predetermined thickness.
2. Device according to Claim 1, characterized in that the said means for redistributing the excess resin are suitable for pouring the said resin, by gravity, approximately into the centre of the said tank (13').
3. Device according to anyone of the preceding claims, characterized in that the said collecting means and the said redistribution means are attached to the walls of the said tank (13').
4. Device according to Claim 3, characterized in that the said collecting means and the said redistribution means are formed by an inclined slope (15), the upper edge (17) of which hugs the strip upstream of the said accurate gauging means in order to collect the excess resin being poured, by gravity, along the strip and the lower edge (16) of which substantially overhangs the centre of the said tank.
5. Device according to any one of the preceding claims, characterized in that it comprises a tank (13') provided with a cover (20) and means for making the tank (13') pivot approximately about its lower rim close to the strip.
6. Process for coating a layer of predetermined thickness of a liquid resin on a running strip (B) by means of a device according to any one of the preceding claims, which comprises a supply tank (13'), in which process:

   - resin is introduced into the said tank (13') from which it is distributed over the entire width of the strip to be coated,

   - a thick layer of resin is spread out over the strip (B) so that the thickness of this thick layer is at least twice as great as the said predetermined thickness,

   - the thickness of the said thick layer is reduced so as to obtain the said predetermined thickness by removing the amount of resin applied in excess with respect to the said predetermined thickness,

   - the said amount of resin applied in excess is collected in such a way that it is separated from the stream of resin corresponding to the said thick layer entrained by the running of the strip (B),

   - and the said amount of resin collected is redistributed into the said tank (13').