EP0757129B1 - Application system for a device for coating a paper or paperboard sheet - Google Patents

Abstract

A coating application system for an arrangement for coating a web of paper or paper board (2) has a smooth, driven applicator roll which, together with a backing roll (5), forms a coating gap into which a coating medium is delivered from the web entry side. The applicator roll is supported against flexing along the entire length of its side opposite to the backing roll. The applicator roll (10) is supported over its working width by a support element (11) which is held on a rigid holder (25) so that it has restricted movement towards and away from the applicator roll, and the support element can be pushed towards the applicator roll by a pressurised flexible pipe (14) supported by the holder (11,25) and extending along the working length. Also claimed is a coating installation which uses the claimed application system together with a doctor blade metering arrangement. Pref. the support element (11) may be a rod which rotates in a bed (12) which is open on the side facing the applicator roll, which is made of a rubber-like material having limited elasticity, and which is mounted on a rigid holder (13). Alternatively, the support element may be a strip with a smooth surface located in a bed and restricted in its range of movement by mechanical stops. The pneumatically loaded flexible pipe (14) can be divided up into separate sections which can be independently pressurised. Numerous additional features include preferred dimensions and wrap angles for the arrangement.

Description

The invention relates to an application system for a device for coating a Paper or cardboard web according to the preamble of claim 1 and one Coating device with an application system according to the invention.

For coating paper or cardboard webs, devices with a Application system used, from which the coating material directly onto the web or first applied to a roller, which then applied the film Transfer coating material to the web.

The devices for direct coating have a deflecting the web Counter roll on. The application system is in the area wrapped in the web arranged the counter roller and carries coating material in excess on the Web on. There is a metering system in the web running direction at a distance behind the application system arranged with a doctor element, the excess to the desired Streak the streak weight again.

Application systems referred to as roller applicators contain one by means of a Drive rotatable applicator roller, the outer surface of which is in operation with the counter roller forms an application gap, the coating material from the web entry side in Excess is supplied. In the roller applicator known from DE-A-36 23 402 there is a fixed gap between the counter roller and the application roller, the counter roll is therefore not pressed against the web.

The coating devices referred to as film presses have two against one another pivotable press rolls, which form a press nip through which the Web is guided. Application systems are arranged on one or both press rolls, who apply a metered film of coating material to the outer surface, which is then transferred to the web in the press nip. DE-A-40 33 521 describes such a coating device with a transfer roller serving press roll on which an application system with a nozzle chamber is arranged.

The same applies to coating devices with an air knife as a metering element known, the coating material first on a transfer roller to be applied, which it then passes on to the railway (DE-A-40 14 463).

With very large working widths (web widths 8 m and more) and high production speeds (800 m / min and more) it is difficult to get the desired amount to apply the applicator to the web or a roller without the coating becomes uneven. When applied directly to the web, the coating material should the application gap with the lowest possible pressure in the lowest possible Excess quantity are fed, so that not too large an amount in the web is pressed, which can no longer be scraped off later. Stability and dynamism require large diameter applicator rollers, the ones that limit the application gap Accordingly, the lateral surface is no longer designed to be curved can, as it is for optimal hydrodynamic conditions in the order gap for has shown necessary.

WO-A-94/23126 describes a generic application system with an application roller, which has a diameter of 5 mm to 200 mm and the Back roll facing away from the back of a holder over the entire working width is supported against deflection. Due to the small diameter of the Application roller can the dosing system at a short distance behind the application system arranged to cover the penetration distance between application and doctoring to keep low. The support of the applicator roller reduces deflection effects, from the dead weight or the hydrodynamic pressure in the application gap result, considerably, so that smaller gap widths can be set.

The invention is based on the object of a generic application system improve that coating material with different rheological properties evenly and with an adjustable amount directly on the web or on a Roller can be applied.

This object is achieved with the features of patent claim 1.

In the application system according to the invention, an adjustable roller can be used with the application roller Back pressure to the hydrodynamic pressure in the application gap between application roller and the counter roll or a transfer roll wrapped in the web are exercised to influence the hydrodynamic conditions. This can be used to achieve a more even job and / or influence the amount of the order, including the penetration rate in the web.

Since the application roller is supported over its entire length, its diameter is fixed as a freely selectable parameter for optimizing the hydrodynamic conditions in the Order gap and to reduce negative effects, e.g. B. film splitting Available.

The subclaims contain preferred, since particularly advantageous, configurations the invention.

The invention also relates to coating devices.

Figur 1

zeigt in vereinfachter Darstellung ein Auftragsystem mit einer Stange als Stützelement.

Figur 2

zeigt die Seitenansicht einer Beschichtungsvorrichtung mit dem Auftragsystem nach Figur 1 zum direkten Auftragen auf die Bahn.

Figur 3

zeigt in vereinfachter Darstellung ein Auftragsystem mit einer Stützleiste als Stützelement.

Figur 4

zeigt einen vergrößerten Ausschnitt von Figur 3.

Figur 5

zeigt die Seitenansicht einer Beschichtungsvorrichtung, bei der die Bahn zwischen Auftragen und Dosieren gradlinig geführt wird.

The drawing serves to explain the invention with reference to an embodiment shown in simplified form.

Figure 1

shows a simplified representation of an application system with a rod as a support element.

Figure 2

shows the side view of a coating device with the application system of Figure 1 for direct application to the web.

Figure 3

shows a simplified representation of an application system with a support bar as a support element.

Figure 4

shows an enlarged section of Figure 3.

Figure 5

shows the side view of a coating device in which the web is guided in a straight line between application and metering.

A coating device in which the application system the coating material directly onto a paper or cardboard web applies. The use for direct application to a web is particularly advantageous, because with the application system, the hydrodynamic pressure in the application gap can influence the penetration of the coating material into the web crucially depends.

However, the use of the application system according to the invention is not based on that direct orders limited. It can also be used to apply coating material on a press roll of a film press, a transfer roll of an air knife machine or other rollers to make a film on the roller to produce the desired strength and uniformity, which then follows the Paper or cardboard web is delivered.

The coating device has an application system 1 and in the direction of rotation Paper or cardboard web 2 arranged at a distance behind it with a metering system 3 a metering element, preferably a doctor blade 4 as a doctor element. Coating paint is applied in excess from coating system 1 as coating material the paper or cardboard web 2 is applied and then from the metering element (Scraper knife 4) of the metering system 3 to the desired coating weight scraped off again. As an alternative to a scraper knife 4 are as metering elements rotatable squeegee bars, squeegee bars or an air knife can also be used. On Air knife consists of a slot nozzle that extends across the web width a jet of compressed air is directed against the excess film.

Both when applying and when metering, the web 2 is from a counter roller 5, 22 supported over their entire width. In the embodiment according to the figure 1 are the application system 1 and the dosing system 3 on a common path 2 deflecting, driven counter roller 5 arranged. In the embodiment 5, the application system 1 and the metering system 3 are each separate Counter roll 5, 22 assigned.

The metering system 3 according to the exemplary embodiments is constructed in a known manner: The scraper knife 4 is clamped with its foot in a clamping bar 7, which is displaceable in the direction of the counter roller 5 in a doctor bar 8 is stored. The scraper bar 8 is pivotable about the scraper knife tip suspended between two side parts 9 in the frame of the device, so that the Contact force of the doctor knife 4 and the blade angle (= angle of the Have the scraper knife 4 set to the tangent to the counter roller 5).

In all embodiments, the application system 1 contains one with a rotary drive connected applicator roller 10 with a smooth outer surface, which extends over the entire Working width, i. e. the maximum web width. The application roller 10 has a diameter of 40 mm to 600 mm, preferably between 100 mm and 400 mm, and is limited at both ends radially to the counter roller 5 movably mounted to the width of the order gap between it and the counter roller 5 to be able to vary. The application roller 10 is preferably on its outer surface coated with a rubber-elastic material.

The applicator roller 10 of one that extends over its entire length - i.e. over the entire working width Supported element that is movable in the direction of the applicator roller 10 limited is mounted on a rigid holder. The support element is by means of a Support-supporting pressure hose 14 in which extends over the working width Direction to applicator roller 10 can be pressed.

In the embodiments according to FIGS. 1 to 3, the support element is a rod 11 with a circular cross section. The diameter of the rod 11 is less than that the application roller 10, in the present example it is approximately 25 mm. If necessary is connected to a rotary drive on one side. It is in one to the application roller 10 open bed 12 made of a limited elastic, rubber-like Material freely rotatable, which is rigid in a correspondingly designed groove Holder 13 is used and extends over the entire working width. In the lower, the hose 14 is incorporated at the bottom of the part 12 of the bed 12, which can be pressurized with compressed air to the rod 11 against the To apply roller 10. The upper part of the bed 12 widens in a dovetail shape, to seal the holder 13. So that the rod 11 as possible can rotate smoothly in bed 12, the inner walls of the bed 12 are only in sections, interrupted by channels 15 for coolant and lubricant, on the Rod 11 on. The holder 13 is screwed to two side pivot arms 16, which by means of a piston-cylinder unit 17 in the direction of the counter roller 5 and this can be swung away. The pivoting movement to the counter roller 5 can be limited by an adjustable stop 18 to a certain Adjust the working position of the application roller 10 relative to the counter roller 5.

As an alternative to the rod 11, a support mounted in a bed a bar supported by a pressure hose, as used in the DE-A-33 38 323 is described.

In the web running direction immediately in front of the bed 12 is on the swivel arms 16 fixed in the area of the applicator roller 10 ink chamber 19, which itself extends over the entire working width and is open to the application roller 10. The Ink chamber 19 is supplied with coating material via a feed line 20. A guide plate 21 adjoins its upper boundary wall, which is approximately parallel to the outer surface of the applicator roller 10 runs at a short distance from this and ends at a short distance from the counter roller 5, so that only a narrow Overflow channel to the counter roller 5 remains free. The overflowing coating material is returned to the ink chamber 19.

As can be seen from Figure 1, the opening of the ink chamber 19 from the bed 12 of the Rod 11, the rod 11 and the applicator roller 10 completed, only one narrow guide channel between the application roller 10 and the guide plate 21 remains free, through which the coating material meets the application gap between the counter roller 5 and the application roller 10 is fed.

In the embodiment according to Figures 3 and 4, the support element is a Support bar 24 with a smooth surface, of which the applicator roller 10 over its entire Length is supported. The support bar 24 has a uniform length Cross-section and a convex curved surface with which they against the Applicator roller 10 can be pressed. As a rigid holder on which the support strip 24 delimits The lower boundary wall serves to be movable in the direction of the application roller 10 25 of the ink chamber 19. As in the embodiment according to FIG 1 is the ink chamber 19 from the support element on the web exit side completed.

The support strip 24 has inwardly angled legs on both longitudinal sides each of which engages around an outwardly angled guide rail 26 which are attached in parallel at a distance from one another on the wall 25 of the ink chamber 19. The guide rails 26 and the encompassing legs of the support bar 24 are so designed that enough play for the desired mobility of the support bar 24th is present in the direction of the counter roll 10. Between the guide rails 26 the pressure hose 14 is arranged, which thus supports the support bar 24 when compressed air is supplied presses in the direction of the application roller 10. The possibility of movement of the support bar 24 radially to the applicator roller 10 is on the one hand by the angled outward Part of the guide rails 26, the other limited by the wall 25. This Parts act as stops that stop further movement.

A support bar 24 as a support element has a rotatable support rod 11 the advantage that no lateral rotary drive is necessary. The side seal the ink chamber 19 is thus simplified.

If necessary, the support element (support rod 11, support bar 24) on the To press the working width locally differently against the application roller 10, e.g. B. um Irregularities in the application gap between the application roller 10 and the counter roller 5 to compensate, the pressure hose 14 is divided into several Subdivided pressure chambers pressurized with compressed air. Then the Compressed air supply 27 for each chamber through the holder to the outside; in the Exemplary embodiment according to FIGS. 3 and 4 through the ink chamber wall serving as a holder 25th

Except for the support element with its holder, the application system corresponds to the Figures 3 and 4 in its construction of the embodiment described above according to Figure 1; there is also a baffle 21 through which the coating material the application gap between the counter roller 5 and the application roller 10 is supplied.

In operation, a vent is formed via the stop 18 when the pressure hose 14 is vented from 0.01 mm to 2 mm, preferably from about 0.8 mm between the application roller 10 and the lane 2 set. In the ink chamber 19 is coating material in Excess and supplied under pressure by the baffle 21 in the application gap between the counter roller 5 and applicator roller 10 and there to the web 2nd is handed over. The excess coating material runs on the back of the Baffle 21 and is returned to the ink chamber 19. In the order column the order on the web 2 from the co-or counter-driven applicator roller 10 equalized. The amount of coating material applied can can be influenced by the pressure in the pressure hose 14. The pressure hose 14 generated force presses the application roller 10 in the direction of the counter roller 5 and acts thus counteracts the resulting hydrodynamic force in the application gap. Of the The wetting of web 2 and the Color penetration in the web 2 decisively influenced. According to the invention, it can can be set with the pressure in the pressure hose 14 as a manipulated variable. At the same time becomes with the pressure in the direction of the counter roller 5, an equalization of the excess order reached.

The embodiment of Figures 3 and 4 with the support bar 24, the Movement is limited by stops, has the advantage that Order system 1 can also be operated so that a fixed gap between the Applicator roller 10 and the counter roller 5 is set. This is done in the pressure hose 14 no pressure built up. The wall 25 serving as a holder is towards Application roller 10 moves up until the legs of the support bar 24 on it support. The support bar 24 is then moved upward and pushes the application roller 10 in the vertical position with the desired fixed distance to the counter roller 5, 22. The applicator roller 10 is inelastic in this mode of operation supported against the liquid pressure in the application gap.

In the embodiment of Figure 5, the web 2 between the application and Dosing is guided essentially in a straight line, in order to direct the to minimize centrifugal forces acting on the excess film. When coating with very high web speeds of more than 1000 m / min curved path between the application and dosing considerable centrifugal forces on the excess film, which are directed away from the web 2. The Centrifugal forces lead to coating material being sprayed off and / or Unevenness in the excess film, e.g. B. to form lines of tension, the can no longer be balanced during dosing. With the shown in Figure 5 and The configuration of a coating device described below can be at very high web speeds, a coating with a very uniform Achieve line art.

Both when applying and when metering, the web 2 is one of each Counter roll 5, 22 supported over its entire width. Loop 2 wraps around first the counter roller 5 of the application system 1, then becomes straight the counter-roller 22 of the metering system 3 out and leaves it after wrapping at a certain angle. The diameter d1 of the counter roller 5 des Application system 1 is 300 mm to 1000 mm, the diameter d2 of the counter roller 22 of the dosing system 3 is 500 mm to 1500 mm. The distance a the two counter-rollers 5, 22 from each other is chosen as small as possible without touch the counter rollers 5, 22. In any case, it is smaller than 500 mm, preferred smaller than 200 mm.

Within the above ranges, the dimensions of the counter rolls 5, 22 in Dependence on the machine width and speed chosen so that none negative dynamic effects, e.g. B. natural frequencies, the coating process affect.

The counter rolls 5, 22 are suspended in the frame of the coating device that the linear path 23 running between them at an angle α from 0 ° to 90 °, preferably 30 ° to 60 °, rising towards the horizontal. This angular range ensures trouble-free backflow of the metering element doctored coating color.

So that the web 2 leaves the area of the order zone as straight as possible, the Applicator roller 10 arranged so that the angle β1 between the radius r1 Counter roll 5 at the end of the order nip and the straight-line path 22 Is 85 ° to 95 °. The angle β1 is preferably 90 °, so that the web 2 Order gap leaves straight. The web 2 running onto the counter roller 5 is so led that the wrap angle γ1 to 0 ° to the end of the application zone 135 °, preferably 90 ° to 135 °. At the preferred angular range, the Web 2 safely guided smoothly against the counter roller 5 when applying.

The metering system 3 is arranged on its counter roller 22 so that the Dosing line of the dosing element - in FIG. 3 the doctor knife tip - in the area is where the rectilinear web section 23 runs onto the counter roller 22. So will ensures that the web 2 is straight or only insignificant before dosing is curved. The angle β2 between the straight line 23 and the radius r2 of the counter roller 22 to the metering line is 85 ° to 95 °. Behind the The counter roll 22 is wrapped around the metering line by the web 2 at an angle γ2, which is 0 ° to 90 °, preferably 3 ° to 60 °.

The counter rolls 5, 22 are coated on their outer surface with rubber, preferably with a shore hardness of approx. 80.

According to an embodiment not shown in the drawing, the straight line Web section 23 on the uncoated back of one of the two counter rolls 5, 22 circumferential support band supported. In this embodiment they need Counter rolls 4, 5 not to be coated, since the support belt is made of one material is made that has the required elasticity and hardness for application and dosing having. Supporting the web 2 when applying and metering with two separate Counter rolls 5, 22 has the further advantage that there is a controlled web tension can be adjusted between application and dosing. This enables one Minimize the risk of a web breaking during coating.

Claims (16)

1. Application system for an apparatus for coating a paper or board web (2), having an applicator roll (10) with a smooth outer surface which

   with a roll (5), forms an open application gap, to which coating material is supplied from the web entry side,

   can be rotated by means of a drive and

   which is supported against deflection over the entire working width on its rear, facing away from the roll (5),

   characterised in that the applicator roll (10) is supported by a supporting element which extends over the working width and is mounted on a rigid holder (13, 25) such that it can be displaced to a limited extent in the direction of the applicator roll (10), it being possible for the supporting element to be forced in the direction of the applicator roll (10) by means of a pressure hose (14) which is supported on the holder (13, 25) and extends over the working width.
2. Application system according to Claim 1, characterized in that the supporting element is a rod (11) rotatably mounted in the bed (12).
3. Application system according to Claim 1, characterized in that the supporting element is mounted in a bed (12) which extends over the working width, is open towards the applicator roll (10), is fabricated from a rubber-like material of limited elasticity and is fitted into the rigid holder (13), the pressure hose (14) being arranged between the bed (12) and the holder (13).
4. Application system according to Claim 1, characterized by a supporting strip (24) with a smooth surface as a supporting element, which is mounted on the holder (25) by stops such that it can move to a limited extent in the direction of the applicator roll (10), the pressure hose (14) being arranged between the supporting strip (24) and the holder (25).
5. Application system according to Claim 4, characterized in that the supporting strip (24) has a cross section which is uniform over its length and a convexly curved surface.
6. Application system according to one of Claims 1 to 5, characterized in that the pressure hose (14) is subdivided over the working width into a plurality of pressure chambers which can be loaded separately with compressed air.
7. Application system according to one of Claims 1 to 6, characterized in that the applicator roll (10) has a diameter of 40 mm to 600 mm, preferably of 100 mm to 400 mm.
8. Application system according to one of Claims 1 to 7, characterized in that, upstream of the supporting element (11), in the direction of rotation of the roll (5), there is arranged a colour chamber (19) with a feed (20) for coating material, the said chamber being open towards the applicator roll (10).
9. Application system according to Claim 8, characterized in that a guide plate (21) adjoins the upper bounding wall of the colour chamber (19), runs approximately parallel to the outer surface of the applicator roll (10) and ends at a short distance from the roll (5).
10. Apparatus for coating a paper or board web (2), having

    a backing roll (5) which deflects the web (2),

    an application system (1) which is arranged in that region of the backing roll (5) around which the web (2) wraps, the said system applying coating material in excess to the web (2), and

    a metering system (3), arranged at a distance downstream of the application system (1), in the running direction, and having a metering element, in particular a scraper blade (4),

    characterized by an application system (1) according to one or more of Claims 1 to 9, the applicator roll (10) forming the application gap with the backing roll (5).
11. Apparatus according to Claim 10, characterized in that, for the application system (1) and metering system (3), separate backing rolls (5, 22) are arranged at a distance from each other, between which the web (2) is led in a straight line.
12. Apparatus according to Claim 11, characterized in that the diameter d1 of the backing roll (5) of the application system (1) is 300 mm to 1 000 mm, the diameter d2 of the backing roll (22) of the metering system (3) is 500 mm to 1 500 mm and the distance a of the two backing rolls (5, 22) from each other is less than 500 mm, preferably less than 200 mm.
13. Apparatus according to Claim 11 or 12, characterized in that the straight web path (6) runs such that it rises with respect to the horizontal at an angle α of 0° to 90°, preferably of 30° to 60°.
14. Apparatus according to one of Claims 11 to 13, characterized in that the applicator roll (10) of the application system (1) is arranged in such a way that the angle β1 between the radius r1 of the backing roll (5) at the end of the application zone and the straight web path (6) is 85° to 95°, and that the metering system (3) is arranged on its backing roll (22) in such a way that the angle β2 between the straight web path (6) and the radius r2 of the backing roll (5) at the metering line is between 85° and 95°.
15. Apparatus according to one of Claims 11 to 14, characterized in that the web (2) wraps around the backing roll (5) of the application system (1) with a wrap angle γ1 up to the end of the application gap of 0° to 135°, preferably 90° to 135°, and the web (2) wraps around the backing roll (22) of the metering system (3) downstream of the metering line over an angle γ2 which is 0° to 90°, preferably 3° to 60°.
16. Apparatus for coating a paper or board web, having a roll and an application system associated with the roll, which applies a film of coating material to the outer surface of the roll, the said film subsequently being transferred from the roll to the web, characterized by an application system according to one or more of Claims 1 to 9.

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