EP0117212B1 - Device for coating a continually moving sheet or strip - Google Patents

Device for coating a continually moving sheet or strip Download PDF

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Publication number
EP0117212B1
EP0117212B1 EP84420010A EP84420010A EP0117212B1 EP 0117212 B1 EP0117212 B1 EP 0117212B1 EP 84420010 A EP84420010 A EP 84420010A EP 84420010 A EP84420010 A EP 84420010A EP 0117212 B1 EP0117212 B1 EP 0117212B1
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EP
European Patent Office
Prior art keywords
sheet
tank
slot
composition
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84420010A
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German (de)
French (fr)
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EP0117212A1 (en
Inventor
Michel Richard
Alain Angogna
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre Technique Industriel dit "CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSES"
Original Assignee
Centre Technique Industriel dit "CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSES"
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Application filed by Centre Technique Industriel dit "CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSES" filed Critical Centre Technique Industriel dit "CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS CARTONS ET CELLULOSES"
Priority to AT84420010T priority Critical patent/ATE21053T1/en
Publication of EP0117212A1 publication Critical patent/EP0117212A1/en
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Publication of EP0117212B1 publication Critical patent/EP0117212B1/en
Expired legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/22—Addition to the formed paper
    • D21H23/46—Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C3/00—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material
    • B05C3/18—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material only one side of the work coming into contact with the liquid or other fluent material
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H5/00—Special paper or cardboard not otherwise provided for
    • D21H5/0005—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating
    • D21H5/0042—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating by pouring or allowing to flow in a continuous stream onto the surface, the entire stream being carried away by the paper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
    • B05C11/04—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with blades

Definitions

  • the invention relates to a device for coating a continuously moving sheet or strip, such as for example a sheet of paper, cardboard, a film or a fabric, using a composition. liquid or in the form of foam.
  • coating is a treatment operation which consists in coating at least one of the faces of a sheet in continuous movement with an appropriate layer, in order to modify its properties, in particular of surface and / or its properties. mechanical.
  • coating is a treatment operation which consists in coating at least one of the faces of a sheet in continuous movement with an appropriate layer, in order to modify its properties, in particular of surface and / or its properties. mechanical.
  • the device according to the invention can also find applications for other uses, such as for example the coating of films or 'fabrics.
  • the regularity of the deposit is not always constant due to the friction of the sheet on an appreciable surface of the reservoir, which results in a defect in spreading of the coating layer, a defect known under the name of “Orange peel.
  • this device is limited to very fluid compositions, since it does not include any means for equalizing the deposited layer.
  • the "dosage is the operation which consists in depositing a determined quantity of composition on a sheet
  • equalization is the operation which consists in uniformly distributing this quantity deposited on the surface of the sheet.
  • the coating device characteristic of the invention, and for example in the case where a foam is applied, essentially consists of a supply tank (10) in which the coating composition is placed with a foaming agent. This composition is then brought to a foam generator (11), of a type known per se. Using a pipe (13), the foamed composition is brought to a stainless steel tube (14) forming a supply reservoir for the composition.
  • This tube (14) limited at its two ends by size limiters (15) and (16) or the like, such as end drawers, is arranged transversely relative to the direction of advance F of a sheet of paper (17).
  • This reservoir (14) has an opening in the form of a rectilinear slot (18) disposed longitudinally relative to the reservoir and in the vicinity of the place where the moving sheet (17) is applied to this reservoir (14).
  • the foamed composition is pulsed by a pump, not shown, first in a box (12), then from there to the tank (14), more precisely in the supply chamber which will be detailed later. From there, it leaves regularly through the slot (18) to deposit on the moving sheet (17).
  • the coating device consists essentially of an elongated body (20) which, in cross section, takes the form of an arc formed in a material having an excellent coefficient of friction opposite the sheet to be coated (17), excellent resistance to wear and does not deform under the effect of heat.
  • This body or sector (20) may for example be made of plastic, of the polyamide or polycarbonate type, or even of metal.
  • the latter In the area (21) where the sheet (17) comes into contact with this sector (20), the latter has grooves (22, 23, 24) relatively close to each other, not very wide and not very deep. It has been found that for example, for a tank of one hundred millimeters in diameter, three grooves spaced from each other by about fifteen millimeters, two millimeters wide and two millimeters deep gave satisfactory results.
  • Their length is greater than the width of the sheet to be treated and they can be interconnected by other grooves (25) shown in Figure 2. It is necessary that, as already said, the length of these grooves is greater than the width of the sheet to be treated, so that the boundary air layer formed on the moving sheet (17) is eliminated in contact with these grooves (22, 23, 24, 25), then evacuated by the ends of these grooves.
  • the angle of attack formed by the sheet relative to the sector (20) is variable depending on the configuration of the machine. It is desirable that this angle is as open as possible, in order to have minimum friction. However, this angle must be compatible with the fact that the sheet of paper (17) must pass in contact with the grooves (22, 23, 24) intended to evacuate the boundary air layer. To do this, in practice, excellent results are obtained with an angle of between 15 and 30 °, preferably close to 20 °.
  • the body or sector (20) rests by means of fixing screws on a base (26), for example made of stainless steel, which is fixed to the frame by a nut (27) and a threaded rod (28).
  • the supply tube (13) opens onto the side wall of the tube (14). From there, the composition, in particular in the form of foam, enters a generally L-shaped supply chamber (30) whose walls gradually converge towards the slit, so as to bring the coating composition in a regular and homogeneous manner. slot.
  • This slot (18) is arranged just downstream of the axis of symmetry AB.
  • the width of the slot (18), that is to say the distance between the inlet wall (31) and the bevelled blade (33) is most reduced. Excellent results are obtained with widths between five and twenty millimeters, preferably close to ten. In this way, during this journey, which lasts approximately 10- 3 seconds, the sheet (17) has practically no time to impregnate, therefore to become brittle, which allows in combination with the angle ⁇ d ' obtain an optimum dosing effect.
  • this cap (20) with the slot (18) and the blade (33) is interchangeable, which thus makes it possible to have assemblies with blades (33) of different inclination, than the it can conveniently be placed on the coating device by a quick attachment system.
  • the inclined equalizing-dosing blade (33) is applied by a movable wedge (34) to a blade-holder angle (35) integral with the part (36) downstream of the body (20).
  • a screw (37) which is rotated, the corner (34) is made to slide thanks to the space provided in (38).
  • the exit angle ⁇ of the coated sheet (40) relative to the direction of the bevel (42) must be sufficiently open to ensure good tension of the sheet which presses it on the bevel, It must not however be too open , in order to avoid contact of the coated layer on the body of the tube (14).
  • this angle is that formed by the sheet (17) and the bearing surface of the bevel (42) of the blade (33). In practice, this angle should be between approximately 5 and approximately 50 °. If this angle is too closed, we will no longer control the regularity of the deposition of the composition. On the other hand, if this angle is too open, the sheet (17) will be scraped, which will cause significant risks of breakage. In practice, this angle ⁇ may advantageously be close to 30 °.
  • the slot (18) is located just downstream of the axis of symmetry AB, so that when the coated sheet (40) leaves the device, there is no more contact between this device and sheet (40).
  • the walls of the chamber (30) are convergent so that the liquid composition or the pressure coating foam advances in a regular and homogeneous manner to the slot (18). .
  • this convergence must be progressive so as to avoid any stagnation in the composition.
  • the tube (14) includes pressure sensors which are connected to a central member connected to the foam generator (11), so as to ensure a regular flow of the composition.
  • these sensors then immediately transmit information to the central control unit which then corrects the flow rate of the generator (11).
  • membrane sensors or piezo sensors are used for this.
  • the active surface of these sensors can be arranged on the vertical portion shim of the supply chamber (30).
  • a box (12) is placed on the conduit (13), possibly connected to a pressure sensor.
  • the periphery (50) of the tube (14) forms a stator. Inside the tube (14) is a cylinder (51) forming a rotor and driven in movement by a suitable motor, not shown.
  • the gap between the stator (50) and the rotor (51) forms a chamber (52) into which the treatment composition is supplied by suitable means. Advancing in this chamber (52), due to the rotation of the rotor (51), the composition is sheared and, in the case of pseudoplastic or thirotropic compositions, its viscosity decreases.
  • the outer wall of the stator has longitudinal grooves (22, 23) intended to eliminate the layer of boundary air which forms upstream of the axis of symmetry AB and comprises downstream a straight longitudinal slot ( 18) associated with an inclined, bevelled blade (33), fixed by any means to the stator (50).
  • the excess of sheared composition is then evacuated by a channel (54) provided with a non-return blade (55) which prevents the sheared composition from returning to the point of supply of the composition with high viscosity.
  • the channel (54) is provided with a valve (56) which keeps the supply chamber (52) under pressure.
  • This device is particularly advantageous for coating by means of compositions with high viscosity.
  • the rotor (51) can be heated, to further promote the decrease in viscosity.
  • the arrival of the composition in the chamber (52) can be carried out by any suitable means, for example means of the manifold type.
  • compositions which can be used are liquid or are in the form of a foam. These compositions contain mineral and / or organic pigments in dispersion, mixed with binders, such as CMC, starch, latex and the most diverse additives. It is also possible according to the invention to coatings by means of hot-melts.
  • the slot (18) has a length of fifty centimeters and a width (distance: 31, 33) of ten millimeters.
  • a fluid composition containing 10% by weight of starch in water (viscosity: 100 mPa - s), is deposited on a sheet of paper using a device according to Figure 3 about four grams per square meter in dry products. This improves the surface properties.
  • a composition is deposited, this time no longer 10, but 20% by weight of starch. Thanks to the shearing effected in the chamber (52), a reduction in the viscosity is caused and a layer weight comparable to that obtained in Example 1 is deposited on the paper, while having less energy to provide for the subsequent drying of the coated sheet.
  • Example 1 is repeated, but this time no longer using a fluid composition, but a foam composition using the apparatus (11). A similar quantity of material is deposited and the surface properties of the paper are improved in a greater proportion. In addition, a substantial gain in drying energy is achieved.
  • the use of the device with a foamed composition has the advantage of consuming all that is provided by the slit and the air included in the bubbles is entrained by the sheet and / or through this sheet.
  • a sheet of paper is pre-coated using a conventional composition based on latex and calcium carbonate at a concentration of 70% in dry matter.
  • the coating can be carried out at speeds of at least 800 m / min in order to deposit layer weights of 7 to 12 g / m 2 surface.
  • the paper thus treated has a very regular surface.
  • the coating of a paper with poor appearance is carried out in the same way as in Example 4, but by increasing the quantity deposited.
  • the composition spreads excellently.
  • the treated paper does not exhibit any defect in surface appearance. This is due in particular to the fact that the device according to the invention does not include a back-pressure roller.
  • the invention can be used advantageously for all coating treatments such as surfacing, pre-coating, coating, bonding, treatment with hot-melts.
  • the composition can be either liquid or in the form of a foam.
  • the invention can also be used in an aqueous medium or in a solvent medium, in particular for the treatment of tissues.

Abstract

1. Device for coating a continuously moving sheet or strip of paper (17) by means of a pressurized composition, which is liquid or in the form of foam, of the type constituted by : a tank (17) feeding the pressurized composition, placed transversaly with respect to the advance direction of the sheet (17) and partially covered by said sheet, said tank (14) having a rectilinear and longitudinal slot (18) -shaped opening placed close to the area where the moving sheet (17) is applied on said tank (14) and through which the coating composition issues ; means adapted to evacuate the limit layer of air driven by said moving uncoated sheet (17), said means being placed just upstream of the area where said sheet (17) contacts with said tank (14) ; and means (33) parallel to said slot (18), placed just downstream of said slot (8) and against which the coated sheet (40) rests, for simultaneously proportioning and equalizing the composition supplied through the slot (18) ; characterized : in that the periphery of the tank (14) which is turned towards the moving sheet (17) has a cross-section shaped as an arc of circle, the convexity of which is turned towards the moving sheet (17), the rectilinear slot-shaped opening (18) of the tank (14) being made in that section part shaped as an arc of circle ; and in that means for evacuating the limit layer of air driven by the moving sheet (17) are constituted by longitudinal grooves (22, 23, 24) provided in the periphery (20) of the tank (14) having a cross-section shaped as an arc of circle, just upstream (20) of the rectilinear slot-shaped opening (18), said grooves (22, 23, 24) having a length greater than the width of the sheet (17) and being interconnected.

Description

L'invention concerne un dispositif d'enduction d'une feuille ou d'une bande en déplacement continu, tel que par exemple une feuille de papier, de carton, un film ou une étoffe et ce, à l'aide d'une composition liquide ou se présentant sous forme de mousse.The invention relates to a device for coating a continuously moving sheet or strip, such as for example a sheet of paper, cardboard, a film or a fabric, using a composition. liquid or in the form of foam.

Comme on le sait, l'enduction est une opération de traitement qui consiste à revêtir au moins une des faces d'une feuille en déplacement continu d'une couche appropriée, en vue de modifier ses propriétés, notamment de surface et/ou ses propriétés mécaniques. Dans la suite de la description, bien que le plus généralement on se référe à l'enduction de papier, le dispositif selon l'invention peut trouver également des applications à d'autres utilisations, telles que par exemple l'enduction de films ou d'étoffes.As is known, coating is a treatment operation which consists in coating at least one of the faces of a sheet in continuous movement with an appropriate layer, in order to modify its properties, in particular of surface and / or its properties. mechanical. In the following description, although more generally reference is made to the coating of paper, the device according to the invention can also find applications for other uses, such as for example the coating of films or 'fabrics.

L'enduction d'une feuille de papier au moyen d'une composition liquide ou se présentant sous forme de mousse est connue depuis fort longtemps.The coating of a sheet of paper with a liquid composition or in the form of foam has been known for a very long time.

Dans le brevet américain US-A-3 941 902 (correspondant au brevet FR-A-2 219 992), on a décrit un dispositif d'enduction qui se compose essentiellement d'un réservoir d'alimentation de la composition, disposé transversalement par rapport à la direction d'avancée de la feuille et qui présente une ouverture en forme de fente rectiligne longitudinale disposée au voisinage de l'endroit où s'applique sur ce réservoir la feuille en mouvement. La composition alimentée sous pression à partir du réservoir traverse cette fente et vient ainsi se déposer à la surface de la feuille. Malheureusement, l'efficacité de ce dispositif est limitée par le niveau de viscosité et de concentration des compositions utilisées. En effet, la régularité du dépôt n'est pas toujours constante du fait des frottements de la feuille sur une surface appréciable du réservoir, ce qui se traduit par un défaut d'étalement de la couche d'enduction, défaut connu sous le nom de « peau d'orange (orange peel). En pratique, ce dispositif est limité à des compositions très fluides, car il ne comporte aucun moyen égalisateur de la couche déposée.In American patent US-A-3,941,902 (corresponding to patent FR-A-2,219,992), a coating device has been described which essentially consists of a reservoir for supplying the composition, arranged transversely by relative to the direction of advancement of the sheet and which has an opening in the form of a longitudinal rectilinear slot arranged in the vicinity of the place where the moving sheet is applied to this reservoir. The composition supplied under pressure from the reservoir passes through this slot and is thus deposited on the surface of the sheet. Unfortunately, the effectiveness of this device is limited by the level of viscosity and concentration of the compositions used. In fact, the regularity of the deposit is not always constant due to the friction of the sheet on an appreciable surface of the reservoir, which results in a defect in spreading of the coating layer, a defect known under the name of “Orange peel. In practice, this device is limited to very fluid compositions, since it does not include any means for equalizing the deposited layer.

Comme on le sait, en papeterie, le « dosage est l'opération qui consiste à déposer une quantité déterminée de composition sur une feuille, alors que « l'égalisation » est l'opération qui consiste à répartir uniformément cette quantité déposée à la surface de la feuille.As we know, in stationery, the "dosage is the operation which consists in depositing a determined quantity of composition on a sheet, while" equalization "is the operation which consists in uniformly distributing this quantity deposited on the surface of the sheet.

Jusqu'à ce jour, en couchage, ces deux opérations sont toujours distinctes, car on estimait que l'on ne pouvait enduire dans de bonnes conditions que lorsque la feuille support avait été préalablement bien imprégnée par migration capillaire de la phase aqueuse de la composition d'enduction, ce qui impliquait qu'il y ait une distance appréciable entre le poste de dosage et le poste d'égalisation.Until now, in coating, these two operations have always been distinct, since it was believed that it was only possible to coat under good conditions when the support sheet had been previously well impregnated by capillary migration of the aqueous phase of the composition. coating, which meant that there was a considerable distance between the dosing station and the equalization station.

Dans la demande de brevet FR-A-2 375 914 (77.39 758). on a décrit un dispositif particulièrement adapté aux mousses, dans lequel celles-ci débouchent dans un espace au contact duquel arrive la feuille à traiter, cet espace étant connecté à une chambre sous pression atmosphérique ou sous vide. Cette chambre est destinée à l'évacuation de l'air inclus dans les bulles après leur éclatement. Or, comme il s'agit d'un espace ouvert, le niveau de pression d'application de la mousse est limité, ce qui nuit au dépôt de la mousse sur la feuille à grande vitesse. En outre, comme l'appareil ne comporte pas de moyen égalisateur, le bord aval du réservoir ne pouvant remplir correctement cette fonction, on retrouve les mêmes défauts qu'avec le dispositif précédent.In patent application FR-A-2 375 914 (77.39 758). a device has been described which is particularly suitable for foams, in which the latter open into a space in contact with which the sheet to be treated arrives, this space being connected to a chamber under atmospheric pressure or under vacuum. This chamber is intended for the evacuation of the air included in the bubbles after they burst. However, since it is an open space, the level of pressure for applying the foam is limited, which affects the deposition of the foam on the sheet at high speed. In addition, as the device does not include an equalizing means, the downstream edge of the tank not being able to correctly fulfill this function, we find the same faults as with the previous device.

Par ailleurs, comme on le sait, lorsqu'une feuille ou une bande se déplace en mouvement continu, notamment à grandes vitesses, il se forme toujours une couche d'air limite provoquée et entraînée par ce déplacement. Il s'agit d'une couche d'air laminaire qui est au contact de la feuille et se déplace avec celle-ci. Ce phénomène, bien connu, gêne fortement le dépôt des compositions d'enduction sur la bande.Furthermore, as is known, when a sheet or a strip moves in continuous movement, in particular at high speeds, there is always a layer of boundary air caused and entrained by this movement. It is a layer of laminar air which is in contact with the sheet and moves with it. This well-known phenomenon greatly hinders the deposition of coating compositions on the strip.

Dans le brevet allemand DE-A-2 055 405, on a décrit un dispositif d'enduction du type énoncé dans le préambule de la revendication 1. Dans ce dispositif, la feuille portée et entraînée par un contre-rouleau est amenée au voisinage d'un ensemble comprenant dans l'ordre :

  • un réservoir d'alimentation de la composition sous pression, disposé transversalement par rapport à la direction d'avancée de la feuille et partiellement embrassé par ladite feuille, ledit réservoir présentant une ouverture en forme de fente rectiligne longitudinale disposée au voisinage de l'endroit où s'applique la feuille en mouvement sur ce réservoir et à travers laquelle débouche la composition d'enduction ;
  • des moyens aptes à évacuer la couche d'air limite entraînée par ladite feuille non enduite en mouvement, disposés juste en amont de la zone où cette feuille entre en contact avec ledit réservoir ;
  • une barre ou une lame transversale parallèle à la fente biseautée, inclinée, disposée juste en aval de cette fente et contre laquelle s'appuie la fente enduite.
  • Ici, le contre-rouleau est nécessaire pour supporter la feuille qui a été fragilisée par la pénétration de la composition dans la feuille et le coin doseur ne fait que doser le poids de la couche déposée sans l'égaliser, puisque l'excès de cette composition déposée est évacué pour être récupéré et recyclé. Ce dispositif ne peut être utilisé avec des compositions concentrées et visqueuses (par exemple contenant au moins 60 % de matières solides), car du fait de la large ouverture de la fente (de l'ordre de dix centimètres et plus), la concentration va augmenter au voisinage du coin doseur, ce qui risque d'engendrer des défauts, tels que rayures longitudinales, étalement irrégulier, d'où difficultés de contrôler la quantité déposée. De plus, avec des papiers support ayant un mauvais épair, les défauts sont accentués par le contre-rouleau.
In German patent DE-A-2 055 405, a coating device of the type stated in the preamble of claim 1 has been described. In this device, the sheet carried and driven by a counter-roller is brought to the vicinity of '' a set comprising in order:
  • a reservoir for supplying the composition under pressure, disposed transversely to the direction of advancement of the sheet and partially embraced by said sheet, said reservoir having an opening in the form of a longitudinal rectilinear slot arranged in the vicinity of where the sheet in motion is applied to this reservoir and through which the coating composition opens;
  • means capable of evacuating the boundary air layer entrained by said moving uncoated sheet, arranged just upstream of the zone where this sheet comes into contact with said reservoir;
  • a bar or a transverse blade parallel to the beveled, inclined slot, arranged just downstream of this slot and against which the coated slot bears.
  • Here, the counter-roller is necessary to support the sheet which has been weakened by the penetration of the composition into the sheet and the metering wedge only measures the weight of the layer deposited without equalizing it, since the excess of this deposited composition is discharged to be recovered and recycled. This device cannot be used with concentrated and viscous compositions (for example containing at least 60% solids), because due to the wide opening of the slit (of the order of ten centimeters and more), the concentration will increase in the vicinity of the metering corner, which may cause defects, such as longitudinal scratches, spread irregular, hence difficulties in controlling the quantity deposited. In addition, with backing papers having a poor look, the defects are accentuated by the backing roller.

L'invention pallie les inconvénients des dispositifs décrits ci-dessus. Elle concerne un dispositif d'enduction d'une feuille ou d'une bande en déplacement continu, à l'aide d'une composition sous pression liquide ou sous forme de mousse, du type constitué par :

  • un réservoir d'alimentation de la composition, disposé transversalement par rapport à la direction d'avancée de la feuille, et partiellement embrassé par ladite feuille, ce réservoir présentant une ouverture en forme de fente rectiligne longitudinale disposée au voisinage de l'endroit où s'applique sur ce réservoir la feuille en mouvement, et à travers laquelle débouche la composition d'enduction ;
  • des moyens aptes à évacuer la couche d'air limite entraînée par ladite feuille non enduite en mouvement, disposés juste en amont de la zone où cette feuille entre en contact avec le réservoir ;
  • et des moyens parallèles à la fente disposés juste en aval de cette fente et contre lesquels s'appuie la feuille enduite pour doser et égaliser simultanément la composition distribuée par la fente.
The invention overcomes the drawbacks of the devices described above. It relates to a device for coating a sheet or a strip in continuous movement, using a composition under liquid pressure or in the form of foam, of the type consisting of:
  • a reservoir for supplying the composition, arranged transversely to the direction of advancement of the sheet, and partially embraced by said sheet, this reservoir having an opening in the form of a longitudinal rectilinear slot disposed in the vicinity of the place where s 'applies to this tank the moving sheet, and through which the coating composition opens;
  • means capable of evacuating the boundary air layer entrained by said moving uncoated sheet, arranged just upstream of the zone where this sheet comes into contact with the reservoir;
  • and means parallel to the slot arranged just downstream of this slot and against which the coated sheet bears to simultaneously dose and equalize the composition distributed by the slot.

Ce dispositif se caractérise :

  • en ce que la périphérie du réservoir qui est tournée vers la feuille en mouvement a une section transversale en forme d'arc de cercle, dont la convexité est tournée vers la feuille en mouvement, l'ouverture en forme de fente rectiligne du réservoir étant ménagée dans cette partie de section en forme d'arc de cercle ;
  • et en ce que les moyens pour évacuer la couche d'air limite entraînée par la feuille en mouvement, sont constitués par des rainures longitudinales ménagées à la périphérie du réservoir de section transversale en arc de cercle, juste en amont de l'ouverture en forme de fente rectiligne, lesdites rainures ayant une longueur supérieure à la largeur de la feuille et étant reliées entre elles.
This device is characterized:
  • in that the periphery of the reservoir which faces the moving sheet has a cross-section in the form of an arc of a circle, the convexity of which faces the moving sheet, the opening in the form of a rectilinear slot in the reservoir being provided in this section of section in the shape of an arc of a circle;
  • and in that the means for evacuating the boundary air layer entrained by the moving sheet, consist of longitudinal grooves formed at the periphery of the tank of cross-section in an arc of a circle, just upstream of the shaped opening rectilinear slot, said grooves having a length greater than the width of the sheet and being interconnected.

Avantageusement, en pratique :

  • le secteur du réservoir embrassé par la feuille en mouvement de section transversale en forme d'arc de cercle est réalisé en un matériau ayant un faible coefficient de frottement par rapport à ladite feuille ;
  • les parois de la chambre d'alimentation de la composition placée dans le réservoir et aboutissant à l'ouverture en forme de fente convergent vers ladite fente, afin d'éviter la création de zones mortes dans ladite chambre d'alimentation ;
  • la chambre d'alimentation de la composition placée dans le réservoir et connectée à la fente, comporte des moyens aptes à cisailler la composition afin d'en diminuer la viscosité, constitués par un cylindre creux formant stator, dans lequel débouche la composition de traitement à viscosité élevée et par un cylindre interne rotatif concentrique au stator, formant rotor, le cisaillement résultant de la rotation du rotor dans le stator.
Advantageously, in practice:
  • the sector of the reservoir embraced by the moving sheet of cross section in the form of an arc of a circle is made of a material having a low coefficient of friction with respect to said sheet;
  • the walls of the supply chamber of the composition placed in the reservoir and leading to the slot-shaped opening converge towards said slot, in order to avoid the creation of dead zones in said supply chamber;
  • the composition supply chamber placed in the reservoir and connected to the slot, comprises means capable of shearing the composition in order to reduce its viscosity, constituted by a hollow cylinder forming a stator, into which the treatment composition opens out. high viscosity and by a rotary internal cylinder concentric with the stator, forming rotor, the shearing resulting from the rotation of the rotor in the stator.

La manière dont l'invention peut être réalisée et les avantages qui en découlent ressortiront mieux de la description qui suit, donnée à titre indicatif et non limitatif et à l'appui des figures annexées.

  • La figure 1 est une représentation d'un dispositif d'enduction conforme à l'invention.
  • La figure 2 est une autre représentation plus détaillée de ce dispositif.
  • La figure 3 est une vue en coupe de ce dispositif d'enduction.
  • La figure 4 représente une lame biseauté caractéristique de l'invention sur laquelle est appliquée la feuille enduite en déplacement.
  • La figure 5 représente un autre mode de réalisation particulier de l'invention.
The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the description which follows, given by way of non-limiting example and in support of the appended figures.
  • Figure 1 is a representation of a coating device according to the invention.
  • Figure 2 is another more detailed representation of this device.
  • Figure 3 is a sectional view of this coating device.
  • FIG. 4 represents a beveled blade characteristic of the invention on which the coated sheet is applied on the move.
  • FIG. 5 represents another particular embodiment of the invention.

Le dispositif d'enduction, caractéristique de l'invention, et par exemple dans le cas d'espèce où on applique une mousse, se compose essentiellement d'un bac d'alimentation (10) dans lequel est placée la composition d'enduction avec un agent moussant. Cette composition est ensuite amenée à un générateur de mousse (11), d'un type en soi connu. A l'aide d'une tuyauterie (13), la composition moussée est amenée à un tube (14) en acier inoxydable formant réservoir d'alimentation de la composition. Ce tube (14) limité à ses deux extrémités par des limiteurs (15) et (16) de format ou analogues, tels que des tiroirs d'extrémité, est disposé transversalement par rapport à la direction d'avancée F d'une feuille de papier (17). Ce réservoir (14) présente une ouverture en forme de fente rectiligne (18) disposée longitudinalement par rapport au réservoir et au voisinage de l'endroit où la feuille en mouvement (17) s'applique sur ce réservoir (14). Depuis le générateur (11), la composition moussée est pulsée par une pompe, non représentée, tout d'abord dans un caisson (12), puis de là dans le réservoir (14), plus précisément dans la chambre d'alimentation qui sera détaillée ultérieurement. De là, elle sort régulièrement par la fente (18) pour se déposer sur la feuille en mouvement (17).The coating device, characteristic of the invention, and for example in the case where a foam is applied, essentially consists of a supply tank (10) in which the coating composition is placed with a foaming agent. This composition is then brought to a foam generator (11), of a type known per se. Using a pipe (13), the foamed composition is brought to a stainless steel tube (14) forming a supply reservoir for the composition. This tube (14) limited at its two ends by size limiters (15) and (16) or the like, such as end drawers, is arranged transversely relative to the direction of advance F of a sheet of paper (17). This reservoir (14) has an opening in the form of a rectilinear slot (18) disposed longitudinally relative to the reservoir and in the vicinity of the place where the moving sheet (17) is applied to this reservoir (14). From the generator (11), the foamed composition is pulsed by a pump, not shown, first in a box (12), then from there to the tank (14), more precisely in the supply chamber which will be detailed later. From there, it leaves regularly through the slot (18) to deposit on the moving sheet (17).

En se référant à la figure 3, le dispositif d'enduction se compose essentiellement d'un corps allongé (20) qui, en section transversale, affecte la forme d'un arc de cercle réalisé en un matériau ayant un excellent coefficient de frottement vis-à-vis de la feuille à enduire (17), une excellente résistance à l'usure et ne se déformant pas sous l'effet de la chaleur. Ce corps ou secteur (20) peut être par exemple en matière plastique, du type polyamide ou polycarbonate, voire en métal. Dans la zone (21) où la feuille (17) entre en contact avec ce secteur (20), ce dernier comporte des rainures (22, 23, 24) relativement rapprochées l'une de l'autre, peu larges et peu profondes. On a trouvé que par exemple, pour un réservoir de cent millimètres de diamètre, trois rainures espacées l'une de l'autre d'environ quinze millimètres, larges de deux millimètres et profondes de deux millimètres donnaient des résultats satisfaisants.Referring to Figure 3, the coating device consists essentially of an elongated body (20) which, in cross section, takes the form of an arc formed in a material having an excellent coefficient of friction opposite the sheet to be coated (17), excellent resistance to wear and does not deform under the effect of heat. This body or sector (20) may for example be made of plastic, of the polyamide or polycarbonate type, or even of metal. In the area (21) where the sheet (17) comes into contact with this sector (20), the latter has grooves (22, 23, 24) relatively close to each other, not very wide and not very deep. It has been found that for example, for a tank of one hundred millimeters in diameter, three grooves spaced from each other by about fifteen millimeters, two millimeters wide and two millimeters deep gave satisfactory results.

Ces rainures (22, 23, 24) longitudinales, disposées juste en amont de l'axe de symétrie AB du secteur (20) embrassé par la feuille (17) par rapport au sens de déplacement de cette feuille, sont taillées à la périphérie du secteur embrassé (20) du réservoir (14). Leur longueur est supérieure à la largeur de la feuille à traiter et elles peuvent être reliées entre elles par d'autres rainures (25) montrées à la figure 2. Il faut que, comme déjà dit, la longueur de ces rainures soit supérieure à la largeur de la feuille à traiter, de manière à ce que la couche d'air limite formée sur la feuille en déplacement (17) soit éliminée au contact de ces rainures (22, 23, 24, 25), puis évacuée par les extrémités de ces rainures.These longitudinal grooves (22, 23, 24), arranged just upstream of the axis of symmetry AB of the sector (20) embraced by the sheet (17) relative to the direction of movement of this sheet, are cut at the periphery of the embraced sector (20) of the reservoir (14). Their length is greater than the width of the sheet to be treated and they can be interconnected by other grooves (25) shown in Figure 2. It is necessary that, as already said, the length of these grooves is greater than the width of the sheet to be treated, so that the boundary air layer formed on the moving sheet (17) is eliminated in contact with these grooves (22, 23, 24, 25), then evacuated by the ends of these grooves.

L'angle d'attaque a que forme la feuille par rapport au secteur (20), est variable en fonction de la configuration de la machine. Il est souhaitable que cet angle soit aussi ouvert que possible, afin d'avoir des frictions minimums. Toutefois, cet angle doit être compatible avec le fait que la feuille de papier (17) doit passer au contact des rainures (22, 23, 24) destinées à évacuer la couche d'air limite. Pour ce faire, en pratique, on obtient d'excellents résultats avec un angle compris entre 15 et 30°, de préférence voisin de 20°.The angle of attack formed by the sheet relative to the sector (20) is variable depending on the configuration of the machine. It is desirable that this angle is as open as possible, in order to have minimum friction. However, this angle must be compatible with the fact that the sheet of paper (17) must pass in contact with the grooves (22, 23, 24) intended to evacuate the boundary air layer. To do this, in practice, excellent results are obtained with an angle of between 15 and 30 °, preferably close to 20 °.

Le corps ou secteur (20) repose grâce à des vis de fixation sur une embase (26), par exemple en acier inoxydable, qui se fixe au bâti par un écrou (27) et une tige filetée (28). Le tube d'alimentation (13) débouche sur la paroi latérale du tube (14). De là, la composition notamment sous forme de mousse, pénètre dans une chambre d'alimentation (30) de forme générale en L dont les parois convergent progressivement vers la fente, de manière à amener la composition d'enduction de façon régulière et homogène à la fente.The body or sector (20) rests by means of fixing screws on a base (26), for example made of stainless steel, which is fixed to the frame by a nut (27) and a threaded rod (28). The supply tube (13) opens onto the side wall of the tube (14). From there, the composition, in particular in the form of foam, enters a generally L-shaped supply chamber (30) whose walls gradually converge towards the slit, so as to bring the coating composition in a regular and homogeneous manner. slot.

Les parois (31) et (32) de cette chambre d'alimentation (30) débouchent à la périphérie du tube (14) pour former la fente rectiligne longitudinale (18) par laquelle sortira la composition d'enduction. Cette fente (18) est disposée juste en aval de l'axe de symétrie AB.The walls (31) and (32) of this supply chamber (30) open at the periphery of the tube (14) to form the longitudinal straight slot (18) through which the coating composition will exit. This slot (18) is arranged just downstream of the axis of symmetry AB.

Juste en aval de cette fente (18), est disposée une lame biseautée (33) rigide, parallèlement à cette fente (18). Cette lame (33), montrée à la figure 4, est donc disposée transversalement par rapport à la direction d'avancée de la feuille (17) sur une face de laquelle a été déposée la composition d'enduction (41). Grâce au biseau (42) de la lame (33), sur lequel repose d'ailleurs la feuille en mouvement, on obtient simultanément un effet égalisateur et doseur. En d'autres termes :

  • l'effet doseur est obtenu par l'angle p formé entre la lame (33) et la feuille en mouvement (17) en combinaison avec la tension appliquée sur la feuille (17) ;
  • et l'effet égalisateur est obtenu par la rigidité et la rectitude de cette lame (33).
Just downstream of this slot (18), is disposed a rigid bevelled blade (33), parallel to this slot (18). This blade (33), shown in Figure 4, is therefore arranged transversely to the direction of advance of the sheet (17) on one side of which has been deposited the coating composition (41). Thanks to the bevel (42) of the blade (33), on which moreover rests the moving sheet, an equalizing and metering effect is simultaneously obtained. In other words:
  • the metering effect is obtained by the angle p formed between the blade (33) and the moving sheet (17) in combination with the tension applied to the sheet (17);
  • and the equalizing effect is obtained by the rigidity and straightness of this blade (33).

Selon une caractéristique essentielle de l'invention, la largeur de la fente (18), c'est-à-dire la distance entre la paroi d'entrée (31) et la lame biseautée (33) est des plus réduites. On obtient d'excellents résultats avec des largeurs comprises entre cinq et vingt millimètres, de préférence voisines de dix. De la sorte, pendant ce trajet, qui dure environ 10-3 seconde, la feuille (17) n'a pratiquement pas le temps de s'imprégner, donc de se fragiliser, ce qui permet en combinaison avec l'angle β d'obtenir un effet doseur optima.According to an essential characteristic of the invention, the width of the slot (18), that is to say the distance between the inlet wall (31) and the bevelled blade (33) is most reduced. Excellent results are obtained with widths between five and twenty millimeters, preferably close to ten. In this way, during this journey, which lasts approximately 10- 3 seconds, the sheet (17) has practically no time to impregnate, therefore to become brittle, which allows in combination with the angle β d ' obtain an optimum dosing effect.

Dans une forme de réalisation pratique, cette calotte (20) avec la fente (18) et la lame (33) est interchangeable, ce qui permet ainsi d'avoir des ensembles avec des lames (33) d'inclinaison différente, que l'on pourra commodément placer sur le dispositif d'enduction par un système d'attache rapide.In a practical embodiment, this cap (20) with the slot (18) and the blade (33) is interchangeable, which thus makes it possible to have assemblies with blades (33) of different inclination, than the it can conveniently be placed on the coating device by a quick attachment system.

Dans une forme pratique, la lame inclinée égalisatrice-doseuse (33) est appliquée par un coin mobile (34) sur une cornière porte-lame (35) solidaire de la partie (36) aval du corps (20). Par une vis (37), que l'on tourne, on fait coulisser le coin (34) grâce à l'espace ménagé en (38).In a practical form, the inclined equalizing-dosing blade (33) is applied by a movable wedge (34) to a blade-holder angle (35) integral with the part (36) downstream of the body (20). By a screw (37), which is rotated, the corner (34) is made to slide thanks to the space provided in (38).

Lorsque l'on désire changer l'angle d'inclinaison de la lame (33), il suffit de changer la cornière (35) et plus précisément la forme de cette cornière, ainsi que le coin coulissable (34), réalisé également en matière plastique. Ce coin (34) peut, comme déjà dit, coulisser et ce, grâce au jeu (38).When it is desired to change the angle of inclination of the blade (33), it suffices to change the angle (35) and more precisely the shape of this angle, as well as the sliding corner (34), also made of material. plastic. This corner (34) can, as already said, slide and this, thanks to the game (38).

L'angle de sortie γ de la feuille enduite (40) par rapport à la direction du biseau (42) doit être suffisamment ouvert pour assurer une bonne tension de la feuille qui la plaque sur le biseau, Il ne doit pas être toutefois trop ouvert, afin d'éviter le contact de la couche enduite sur le corps du tube (14).The exit angle γ of the coated sheet (40) relative to the direction of the bevel (42) must be sufficiently open to ensure good tension of the sheet which presses it on the bevel, It must not however be too open , in order to avoid contact of the coated layer on the body of the tube (14).

Comme déjà dit, l'angle le plus important est celui formé par la feuille (17) et la surface portante du biseau (42) de la lame (33). En pratique, cet angle doit être compris entre environ 5 et environ 50°. Si cet angle est trop fermé, on ne maîtrisera plus la régularité du dépôt de la composition. En revanche, si cet angle est trop ouvert, on raclera la feuille (17), ce qui provoquera des risques importants de casses. En pratique, cet angle β peut être avantageusement voisin de 30°.As already said, the most important angle is that formed by the sheet (17) and the bearing surface of the bevel (42) of the blade (33). In practice, this angle should be between approximately 5 and approximately 50 °. If this angle is too closed, we will no longer control the regularity of the deposition of the composition. On the other hand, if this angle is too open, the sheet (17) will be scraped, which will cause significant risks of breakage. In practice, this angle β may advantageously be close to 30 °.

Comme déjà dit, il est indispensable que la fente (18) soit située juste en aval de l'axe de symétrie AB, de sorte que lorsque la feuille enduite (40) quitte le dispositif, il n'y ait plus de contact entre ce dispositif et la feuille (40). De même, comme déjà dit, il importe que les parois de la chambre (30) soient convergentes de manière à ce que la composition liquide ou la mousse d'enduction sous pression avance de manière régulière et homogène jusqu'à la fente (18). En outre, il faut que cette convergence soit progressive de manière à éviter toute stagnation de la composition. Dans une variante, le tube (14) comporte des capteurs de pression qui sont reliés à un organe central connecté au générateur de mousse (11), de manière à assurer un débit régulier de la composition. Si d'aventure, en cours de traitement, le débit varie, ces capteurs transmettent alors immédiatement une information à l'organe central de commande qui corrige alors le débit du générateur (11). On utilise pour ce faire, avantageusement, des capteurs à membranes ou des capteurs piezo. Dans une forme de réalisation avantageuse, la surface active de ces capteurs peut être disposée sur la portion verticale de la chambre d'alimentation (30). De même, afin d'absorber les fluctuations de débit de la composition moussée juste avant l'entrée dans le tube fendu (14), on place sur le conduit (13) un caisson (12) éventuellement connecté à un capteur de pression.As already said, it is essential that the slot (18) is located just downstream of the axis of symmetry AB, so that when the coated sheet (40) leaves the device, there is no more contact between this device and sheet (40). Likewise, as already said, it is important that the walls of the chamber (30) are convergent so that the liquid composition or the pressure coating foam advances in a regular and homogeneous manner to the slot (18). . In addition, this convergence must be progressive so as to avoid any stagnation in the composition. Alternatively, the tube (14) includes pressure sensors which are connected to a central member connected to the foam generator (11), so as to ensure a regular flow of the composition. If by chance, during treatment, the flow rate varies, these sensors then immediately transmit information to the central control unit which then corrects the flow rate of the generator (11). Advantageously, membrane sensors or piezo sensors are used for this. In an advantageous embodiment, the active surface of these sensors can be arranged on the vertical portion shim of the supply chamber (30). Similarly, in order to absorb the fluctuations in the flow rate of the foamed composition just before entering the split tube (14), a box (12) is placed on the conduit (13), possibly connected to a pressure sensor.

Dans la forme de réalisation illustrée à la figure 5, la périphérie (50) du tube (14) forme stator. On dispose à l'intérieur du tube (14) un cylindre (51) formant rotor et entraîné en mouvement par un moteur approprié non représenté. L'intervalle entre le stator (50) et le rotor (51) forme une chambre (52) où la composition de traitement est amenée par des moyens appropriés. En avançant dans cette chambre (52), du fait de la rotation du rotor (51), la composition est cisaillée et, dans le cas de compositions pseudo- plastiques ou thirotropiques, sa viscosité diminue. Dans ce mode de réalisation, la paroi extérieure du stator présente des rainures longitudinales (22, 23) destinées à éliminer la couche d'air limite qui se forme en amont de l'axe de symétrie AB et comporte en aval une fente longitudinale rectiligne (18) associée à une lame inclinée, biseautée (33), fixée par un moyen quelconque au stator (50). L'excès de composition cisaillée est ensuite évacué par un canal (54) muni d'une lame anti-retour (55) qui empêche la composition cisaillée de revenir au point d'alimentation de la composition à haute viscosité. Le canal (54) est muni d'une vanne (56) qui permet de maintenir sous pression la chambre d'alimentation (52). Ce dispositif est particulièrement avantageux pour l'enduction au moyen de compositions à haute viscosité. Dans une variante, le rotor (51) peut être chauffé, afin de favoriser encore la diminution de la viscosité. L'arrivée de la composition dans la chambre (52) peut être effectuée par tous moyens appropriés, par exemple des moyens du type manifolds.In the embodiment illustrated in Figure 5, the periphery (50) of the tube (14) forms a stator. Inside the tube (14) is a cylinder (51) forming a rotor and driven in movement by a suitable motor, not shown. The gap between the stator (50) and the rotor (51) forms a chamber (52) into which the treatment composition is supplied by suitable means. Advancing in this chamber (52), due to the rotation of the rotor (51), the composition is sheared and, in the case of pseudoplastic or thirotropic compositions, its viscosity decreases. In this embodiment, the outer wall of the stator has longitudinal grooves (22, 23) intended to eliminate the layer of boundary air which forms upstream of the axis of symmetry AB and comprises downstream a straight longitudinal slot ( 18) associated with an inclined, bevelled blade (33), fixed by any means to the stator (50). The excess of sheared composition is then evacuated by a channel (54) provided with a non-return blade (55) which prevents the sheared composition from returning to the point of supply of the composition with high viscosity. The channel (54) is provided with a valve (56) which keeps the supply chamber (52) under pressure. This device is particularly advantageous for coating by means of compositions with high viscosity. Alternatively, the rotor (51) can be heated, to further promote the decrease in viscosity. The arrival of the composition in the chamber (52) can be carried out by any suitable means, for example means of the manifold type.

Les compositions d'enduction utilisables sont liquides ou se présentent sous forme de mousse. Ces compositions contiennent des pigments minéraux et/ou organiques en dispersion, en mélange avec des liants, tels que CMC, amidon, latex et des additifs les plus divers. On peut également procéder selon l'invention à des enductions au moyen de hot-melts.The coating compositions which can be used are liquid or are in the form of a foam. These compositions contain mineral and / or organic pigments in dispersion, mixed with binders, such as CMC, starch, latex and the most diverse additives. It is also possible according to the invention to coatings by means of hot-melts.

Dans les exemples qui suivent, qui montrent différentes possibilités d'utilisation de l'invention, la fente (18) a une longueur de cinquante centimètres et une largeur (distance : 31, 33) de dix millimètres.In the examples which follow, which show different possibilities of using the invention, the slot (18) has a length of fifty centimeters and a width (distance: 31, 33) of ten millimeters.

Exemple 1Example 1

A l'aide d'une composition fluide, contenant 10 % en poids d'amidon dans de l'eau (viscosité : 100 mPa - s), on dépose sur une feuille de papier à l'aide d'un dispositif selon figure 3 environ quatre grammes au mètre carré en produits secs. On améliore ainsi les propriétés de surface.Using a fluid composition, containing 10% by weight of starch in water (viscosity: 100 mPa - s), is deposited on a sheet of paper using a device according to Figure 3 about four grams per square meter in dry products. This improves the surface properties.

Exemple 2Example 2

En utilisant un dispositif selon figure 5, on dépose une composition contenant cette fois non plus 10, mais 20 % en poids d'amidon. Grâce au cisaillement effectué dans la chambre (52), on provoque une diminution de la viscosité et on dépose sur le papier un poids de couche comparable à celui obtenu dans l'exemple 1, tout en ayant une moindre quantité d'énergie à fournir pour le séchage ultérieur de la feuille enduite.Using a device according to FIG. 5, a composition is deposited, this time no longer 10, but 20% by weight of starch. Thanks to the shearing effected in the chamber (52), a reduction in the viscosity is caused and a layer weight comparable to that obtained in Example 1 is deposited on the paper, while having less energy to provide for the subsequent drying of the coated sheet.

Exemple 3Example 3

On répète l'exemple 1, mais en utilisant cette fois non plus une composition fluide, mais une composition moussée grâce à l'appareil (11). On dépose une quantité voisine de matière et on améliore les propriétés de surface du papier dans une proportion plus importante. En outre, on réalise un gain substantiel d'énergie de séchage.Example 1 is repeated, but this time no longer using a fluid composition, but a foam composition using the apparatus (11). A similar quantity of material is deposited and the surface properties of the paper are improved in a greater proportion. In addition, a substantial gain in drying energy is achieved.

L'utilisation du dispositif avec une composition moussée présente l'avantage de consommer tout ce qui est apporté par la fente et l'air inclus dans les bulles est entraîné par la feuille et/ou à travers cette feuille.The use of the device with a foamed composition has the advantage of consuming all that is provided by the slit and the air included in the bubbles is entrained by the sheet and / or through this sheet.

Exemple 4Example 4

On réalise le précouchage d'une feuille de papier au moyen d'une composition classique à base de latex et de carbonate de calcium à une concentration de 70 % en matières sèches.A sheet of paper is pre-coated using a conventional composition based on latex and calcium carbonate at a concentration of 70% in dry matter.

Grâce au dispositif selon l'invention, on peut effectuer l'enduction à des vitesses d'au moins 800 m/mn pour déposer des poids de couche de 7 à 12 g/m2fface.Thanks to the device according to the invention, the coating can be carried out at speeds of at least 800 m / min in order to deposit layer weights of 7 to 12 g / m 2 surface.

Le papier ainsi traité a une surface très régulière.The paper thus treated has a very regular surface.

Ces résultats sont impossibles à obtenir dans les mêmes conditions avec une presse encolleuse habituellement utilisée pour le pré-couchage.These results are impossible to obtain under the same conditions with a size press usually used for pre-coating.

Exemple 5Example 5

On réalise le couchage d'un papier à mauvais épair de la même façon qu'à l'exemple 4, mais en augmentant la quantité déposée. La composition s'étale de manière excellente. En particulier, le papier traité ne présente pas de défaut d'aspect de surface. Cela est dû notamment au fait que le dispositif selon l'invention ne comporte pas de rouleau de contre-pression.The coating of a paper with poor appearance is carried out in the same way as in Example 4, but by increasing the quantity deposited. The composition spreads excellently. In particular, the treated paper does not exhibit any defect in surface appearance. This is due in particular to the fact that the device according to the invention does not include a back-pressure roller.

Le dispositif selon l'invention présente de nombreux avantages par rapport à ceux connus à ce jour ou ceux qui sont cités ci-dessus. On peut citer :

  • tout d'abord et surtout le gain d'énergie de séchage, car comme on peut utiliser des compositions de concentration plus élevées, on a ainsi moins d'eau à éliminer ; cet avantage est beaucoup plus marqué avec des compositions moussées :
  • construction facile, investissement réduit et encombrement limité (absence de contre-rouleau) ;
  • une grande versatilité, puisque le même appareil peut servir à enduire des compositions de surfaçage ou de couchage, soit liquides, soit sous forme de mousse ;
  • la possibilité de réaliser des papiers enduits double face, sans que les compositions d'enduction se mélangent lorsque. la feuille se rompt ;
  • coût de fonctionnement réduit, car le changement des lames (33) peut être effectué très rapidement : de plus, les lames étant très courtes, celà nécessite peu de matière pour leur fabrication ;
  • lorsque la composition est moussée, on n'a pratiquement aucune perte de matière ;
  • comme la fente (31) d'alimentation (18) est située très près de la lame (33), l'apport de la couche d'enduction et le lissage de celle-ci sont réalisés simultanément, ce qui est très favorable, car la migration de la phase aqueuse de la composition dans la feuille est réduite, ce qui se traduit par une moindre fragilisation de cette feuille, donc une meilleure résistance et une stabilité de la concentration de la couche déposée, donc la possibilité de travailler avec des concentrations plus élevées, sans risquer des défauts tels que rayures longitudinales, étalement irrégulier, accentuation de l'épair ;
  • l'absence de pincements sur la feuille enduite, ce qui réduit sensiblement les casses ;
  • enfin, la possibilité d'enduire un papier humide.
The device according to the invention has numerous advantages over those known to date or those mentioned above. We can cite :
  • first of all and above all the gain in drying energy, since as it is possible to use compositions of higher concentration, there is thus less water to eliminate; this advantage is much more marked with foam compositions:
  • easy construction, reduced investment and limited space (no backing roll);
  • great versatility, since the same device can be used to coat compositions of surfacing or coating, either liquid or in the form of foam;
  • the possibility of making double-sided coated papers, without the coating compositions mixing when. the leaf breaks;
  • reduced operating cost, because the change of the blades (33) can be carried out very quickly: moreover, the blades being very short, this requires little material for their manufacture;
  • when the composition is foamed, there is practically no loss of material;
  • as the feed slot (31) (18) is located very close to the blade (33), the addition of the coating layer and the smoothing thereof are carried out simultaneously, which is very favorable because the migration of the aqueous phase of the composition into the sheet is reduced, which results in less embrittlement of this sheet, therefore better resistance and stability of the concentration of the deposited layer, therefore the possibility of working with concentrations higher, without risking defects such as longitudinal scratches, uneven spreading, accentuation of the air;
  • the absence of pinching on the coated sheet, which significantly reduces breakage;
  • finally, the possibility of coating wet paper.

De la sorte, l'invention peut être utilisée avantageusement pour tous les traitements d'enduction tels que surfaçage, pré-couchage, couchage, collage, traitement par des hot-melts. Comme déjà dit, la composition peut être soit liquide, soit sous forme de mousse.In this way, the invention can be used advantageously for all coating treatments such as surfacing, pre-coating, coating, bonding, treatment with hot-melts. As already said, the composition can be either liquid or in the form of a foam.

L'invention peut également être utilisée en milieu aqueux ou en milieu solvant, notamment pour le traitement des tissus.The invention can also be used in an aqueous medium or in a solvent medium, in particular for the treatment of tissues.

Elle est particulièrement avantageuse pour l'enduction des papiers, cartons ou similaires.It is particularly advantageous for coating paper, cardboard or the like.

Claims (4)

1. Device for coating a continuously moving sheet or strip of paper (17) by means of a pressurized composition, which is liquid or in the form of foam, of the type constituted by :
a tank (17) feeding the pressurized composition, placed transversaly with respect to the advance direction of the sheet (17) and partially covered by said sheet, said tank (14) having a rectilinear and longitudinal slot (18) -shaped opening placed close to the area where the moving sheet (17) is applied on said tank (14) and through which the coating composition issues ;
means adapted to evacuate the limit layer of air driven by said moving uncoated sheet (17), said means being placed just upstream of the area where said sheet (17) contacts with said tank (14) ;
and means (33) parallel to said slot (18), placed just downstream of said slot (18) and against which the coated sheet (40) rests, for simultaneously proportioning and equalizing the composition supplied through the slot (18) ;
characterized :
in that the periphery of the tank (14) which is turned towards the moving sheet (17) has a cross-section shaped as an arc of circle, the convexity of which is turned towards the moving sheet (17), the rectilinear slot-shaped opening (18) of the tank (14) being made in that section part shaped as an arc of circle ;
and in that means for evacuating the limit layer of air driven by the moving sheet (17) are constituted by longitudinal grooves (22, 23, 24) provided in the periphery (20) of the tank (14) having a cross-section shaped as an arc of circle, just upstream (20) of the rectilinear slot-shaped opening (18), said grooves (22, 23, 24) having a length greater than the width of the sheet (17) and being interconnected.
2. Device for coating a continuously moving sheet of paper or a band (17) according to claim 1, characterized in that the sector (20) of the tank (14) covered by the moving sheet (17) of cross-section shaped as an arc of circle is made in a material having a low friction coefficient with respect to said sheet (17).
3. Device according to any one of claims 1 and 2, characterized in that the walls of the composition-feeding chamber (30) placed in the tank (14) and issuing into the slot-shaped opening (18) converge towards said slot.
4. Device according to any one of claims 1 and 2, characterized in that the composition-feeding chamber (52) placed in the tank (14) and connected to the slot (18), comprises means adapted to shear the composition in order to reduce its viscosity, said means being constituted by a hollow cylinder (50) forming stator, into which issues the treatment composition of high viscosity, and by a rotating internal cylinder (51) concentric with respect to the stator (50), and forming rotor, the shearing action resulting from the rotation of the rotor (51) inside the stator (50).
EP84420010A 1983-02-04 1984-01-26 Device for coating a continually moving sheet or strip Expired EP0117212B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84420010T ATE21053T1 (en) 1983-02-04 1984-01-26 DEVICE FOR COATING A FILM OR TAPE IN CONTINUOUS MOTION.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8301991 1983-02-04
FR8301991A FR2540406B1 (en) 1983-02-04 1983-02-04 DEVICE FOR COATING A SHEET OR A CONTINUOUSLY MOVING STRIP

Publications (2)

Publication Number Publication Date
EP0117212A1 EP0117212A1 (en) 1984-08-29
EP0117212B1 true EP0117212B1 (en) 1986-07-30

Family

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Application Number Title Priority Date Filing Date
EP84420010A Expired EP0117212B1 (en) 1983-02-04 1984-01-26 Device for coating a continually moving sheet or strip

Country Status (5)

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EP (1) EP0117212B1 (en)
AT (1) ATE21053T1 (en)
DE (1) DE3460364D1 (en)
FI (1) FI840452A (en)
FR (1) FR2540406B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3446757A1 (en) * 1984-11-17 1986-05-22 J.M. Voith Gmbh, 7920 Heidenheim PAINTING DEVICE

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GB8412292D0 (en) * 1984-05-14 1984-06-20 Dynamelt Ltd Coating applicator head
AT394668B (en) * 1984-11-17 1992-05-25 Voith Gmbh J M DEVICE FOR COATING CONTINUOUS GOODS WITH A COATING MEASUREMENT
US4581254A (en) * 1985-03-22 1986-04-08 Union Carbide Corporation Foam applicator used in paper treatment
US4912948A (en) * 1985-03-22 1990-04-03 Union Carbide Chemicals And Plastics Company Inc. Vacuum guide used in flexible sheet material treatment
DE3525805A1 (en) * 1985-07-19 1987-01-29 Hesselmann Planatolwerk H DEVICE FOR APPLYING AN ADHESIVE IN THE FORM OF A CROSS-BANDING
JPH0677711B2 (en) * 1986-07-15 1994-10-05 富士写真フイルム株式会社 Coating device
DE3839100A1 (en) * 1988-11-18 1990-05-23 Bematec S A COATING DEVICE FOR MATERIAL RAILS
FI90634C (en) * 1989-01-17 1994-03-10 Valmet Paper Machinery Inc Coating device and method for coating a web
US6406752B1 (en) 2000-02-14 2002-06-18 The Procter & Gamble Company Extrusion die having dynamic flow inducer
AU2002351509A1 (en) * 2001-11-05 2003-05-19 Kimberly-Clark Worldwide, Inc. Foam treatment of tissue webs
US6730171B2 (en) 2001-11-05 2004-05-04 Kimberly-Clark Worldwide, Inc. Nozzle apparatus having a scraper for the application of the foam treatment of tissue webs
DE102022101266A1 (en) 2022-01-20 2023-07-20 Voith Patent Gmbh Process and application device for applying foamed, liquid and pasty application media to a moving application surface

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US3227136A (en) * 1961-10-26 1966-01-04 Eastman Kodak Co Extrusion coating apparatus
BE727407A (en) * 1968-07-31 1969-07-01
DE2055405B2 (en) * 1970-11-11 1973-10-04 Joseph Eck & Soehne, 4000 Duesseldorf Device for applying coating compounds to web-shaped supports
SE383007B (en) * 1973-03-02 1976-02-23 Svenska Cellulosa Ab METHOD OF PRODUCING SURFACE TREATED PAPER IN THE FORM OF A CONTINUOUS PATH
SE416970C (en) * 1977-01-03 1984-12-11 Inventing Ab SET FOR TREATING OR COATING SURFACES, EXAMPLE OF CURRENT MATERIALS

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3446757A1 (en) * 1984-11-17 1986-05-22 J.M. Voith Gmbh, 7920 Heidenheim PAINTING DEVICE
DE3446757C2 (en) * 1984-11-17 1995-05-24 Voith Gmbh J M Coating device

Also Published As

Publication number Publication date
EP0117212A1 (en) 1984-08-29
FR2540406B1 (en) 1986-10-31
FI840452A (en) 1984-08-05
DE3460364D1 (en) 1986-09-04
FR2540406A1 (en) 1984-08-10
ATE21053T1 (en) 1986-08-15
FI840452A0 (en) 1984-02-03

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