EP2314767A1 - Coating device - Google Patents

Abstract

Device (1) for coating a running paper, a cardboard or other fibrous web, comprises: an application unit (2) with a slot opening continuously extending in a transverse direction of the application unit, which is associated with a running counter surface (4); at least one format limiter for adjusting a required width of a coating or a zone of the application; at least one covering element (9) in a radial direction between the slot opening of the application unit and a coated web, and in the transverse direction; and at least one moistening device. Device (1) for coating a running paper, a cardboard or other fibrous web, comprises: an application unit (2) with a slot opening continuously extending in a transverse direction of the application unit, which is associated with a running counter surface (4); at least one format limiter for adjusting a required width of a coating or a zone of the application, where the format limiter is arranged in the slot opening at the application unit; at least one covering element (9), which is seen in a radial direction between the slot opening of the application unit and a coated web, and in the transverse direction, and an area between the format limiter and the minimum width is at least partially covered; and at least one moistening device for delivering a moistening agent for moistening the counter surface.

Description

The invention relates to a device for coating a running paper, cardboard or other fibrous web, comprising a coating unit with a running in the transverse direction of the application aggregate continuous slot opening, wherein the application unit is associated with a running counter surface and having at least one Formatbegrenzer for setting a desired width Coating or zone of the job, wherein the at least one format delimiter is arranged on the application unit, for example in the slot opening,

A generic application device, ie a free-jet nozzle device, for example, from the DE-U1 296 13687.5 known.

The applicator is for direct or indirect application of a coating medium, e.g. Coating color, on the moving web, wherein the applicator comprises a coating serving dosing. In order to be able to determine the application width precisely, in each case a so-called format limiter is arranged in this dosing gap at both ends (driver and drive side).

Such an order facility contributes to the achievement of the necessary quality of the contract in surplus. Therefore, the applicator is a doctor blade element, arranged downstream of a blade or doctor bar, with which the applied coating medium is brought to the desired coating weight, i. is dosed.

However, this application device has the disadvantage that the web width can be varied only within narrow limits. The reason for this is that the transverse distribution can be optimally designed hydraulically only for a narrow variation of the paper web width. The wider the format delimiters are formed, ie the wider the application media supply (seen over the slot width of the application nozzle) is limited the less favorable the flow conditions in the application area change. The flow conditions change in such a way that, on the one hand, zones with lower to even flow, ie "dead corners", are created. On the other hand, zones with higher flow velocity can again arise. This can lead to a highly undesirable, uneven job.

In addition, deposits are formed in the dead corners, which in turn lead to a higher cleaning effort or also lead to line errors, because the deposits peel off from time to time and e.g. be supplied in the form of agglomerates of bladder dosage and lead there to doctor blade.

Concretely, this leads to e.g. an applicator optimally for a web width variation of +/- 100mm at a web width of e.g. four meters can be designed. In the case of a required smaller web width of only two meters on the same coater (applicator), however, the above-mentioned disadvantages occur.

It is therefore an object of the invention to provide an improved Aufragseinrichtung that can be used for a wide range of different web widths and with which the disadvantages mentioned do not occur.

The object is achieved with the features of claim 1. According to the invention, it is provided that at least one cover element is provided which, as seen in the radial direction between the slot opening of the application unit and the web to be coated and seen in the transverse direction, at least partially covers an area between the format delimiter and a minimum web width, and in that at least one moistening device for the sectioned dispensing a moistening agent for moistening the counter surface is present.

By means of this design according to the invention, it is possible for the first time to use the same application device or the same coater for extremely different web widths. Until now, a completely new coater had to be used for each web width be designed, which means enormously high investment costs. Therefore, the device according to the invention can in principle also be used for a "web-wide spreading".

With the at least one moistening device, the device according to the invention can moisten the opposing surface / backing roll in the case of direct application or even the surface of the application roll in the case of indirect application and thus avoid dry running of the doctoring element. The service life of the mating surface, which can also be an applicator roll or an order tape, can be increased thereby.

As application aggregates are all conceivable, known contactless acting coating units used. In particular, it is intended to free-jet commissioned works and curtain applicators, each having a continuous slot and can be changed with format delimiters in their order width. Here, with broad format limitation without application of the invention, the disadvantages described above would result with too high or uneven flows of the application medium.

In the context of the invention, in particular in the case of free-jet application units, it is provided that a doctoring element for metering the applied layer is arranged downstream of the application unit to the desired coating weight. Such a doctor element may be a doctor blade (blade) pressed onto the counter surface or else a rotating doctor rod.

For collecting and returning the not reaching the counter surface or the web and stripped from the doctor blade application medium is a catch element. This collecting element extends from the application unit to the doctor element. The collecting element can be divided into a collecting plate and a return channel, so that both parts can be used either as a combination, or each can be used individually.

In certain cases, it may be expedient if the doctor element is larger, i. is longer than the width of the web or in approximately the length of the counter surface corresponds.

For very small web widths, however, the doctor element can also be made smaller than the length of the counter surface.

In the latter case, and also in the case when the doctor element is formed as a blade, it is expedient to have it at its ends with rounded corners, i. Rounding off. This avoids damage to the roll cover or reduces shrinkage of the sensitive cover.

The invention will be explained in more detail with reference to an embodiment.

Figur 1:

eine erfindungsgemäße, in der Seitenansicht schematisch dargestellte Beschichtungsvorrichtung ,

Figur 2:

eine Draufsicht der erfindungsgemäßen Beschichtungsvorrichtung von Figur 1 in einer ersten Variante,

Figur 3:

eine Draufsicht der erfindungsgemäßen Beschichtungsvorrichtung von Figur 1 in einer zweiten Variante,

Figur 4:

eine Draufsicht der erfindungsgemäßen Beschichtungsvorrichtung von Figur 1 in einer dritten Variante,

In a schematic representation:

FIG. 1:

a coating device according to the invention, schematically shown in side view,

FIG. 2 :

a top view of the coating device of the invention FIG. 1 in a first variant,

FIG. 3:

a top view of the coating device of the invention FIG. 1 in a second variant,

FIG. 4:

a top view of the coating device of the invention FIG. 1 in a third variant,

In the figures, the same reference numerals are provided for the same components. In the FIG. 1 a device 1 for coating a running paper, cardboard or other fibrous web is shown schematically in the side view.

The device 1 has an application unit 2 and a downstream doctor element 3. The application unit 2 and the doctor element 3 are a running in the direction of arrow R counter surface 4 in the form of a roller, which is referred to as a counter roll, assigned to the direct application of a liquid to pasty medium 5 on a paper, cardboard or other fibrous web 6. The usually applied in excess application medium 5, z. As glue, starch or a pigmented coating color passes when doctoring or leveling only by means of doctor element 3 in a below between doctoring point and application point extending collecting element 7. This collecting element 7 consists of a collecting plate 7.1 and a return channel 7.2. Both parts 7.1. and 7.2 may be present as individual components, or arranged as drawn in combination.

The application unit 2 has a transverse slot opening 2.1 extending in the transverse direction Q of the application unit. At least one is used to set a desired width of the coating or zone of the job, at least one format delimiter 8. As a rule, each a Begrenzungsbegrenzer 8 - a shaped piece, which in the example in the slot opening 2.1 is inserted- at both side edges of the web to be coated 6 arranged.

In addition, at least one cover member 9 is provided, which is arranged in the radial direction between the slot opening 2.1 of the application unit 2 and the web 6 to be coated. In addition, at least one moistening device 10 is provided for dispensing a moistening agent 11, such as water, for section-wise moistening of the counterface 4.

In FIG. 2 is a plan view of the coating device of the invention of FIG. 1 shown in a first variant.

The upper figure shows in the transverse direction Q the counter surface or the counter-roller 4 with its length L. In addition, the length PB of a wide web 6, for example, 4 m and to be coated, much narrower track PB ^*, for example, 2 m drawn. One recognizes in the example of the FIG. 2 in that the doctor element 3 is slightly wider than the counter surface 4 and thus also the web width PB / PB ^* .

In the lower figure it can be seen that on both sides of the narrow web PB ^* the cover element 9 is arranged, which extends in transverse direction (Q) and in each case a region between format limiter 8 (this somewhat overlapping) and narrow web PB ^* covered. The overlap ranges by an amount x, z. B. 10 cm, in the narrow web PB ^* into it to create a bar-free edge. It can also be seen that the moistening device 10 emits the moistening agent 11 in order to avoid hot running of the doctoring element 3.

It should be mentioned that, in this variant, the unused order medium application is intercepted outside the web width BP ^* and returned to the working cycle via the catch element 7 already described.

In order to avoid dilution effects with the humectant 11 in this case the collecting element 7 is carried out divided. Alternatively or additionally, the collecting plate 7.1 may be designed so that a mixing of the return from the doctor element (places with water and application medium) is largely avoided.

In FIG. 3 is a plan view of the coating device of the invention of FIG. 1 shown in a second variant.

The upper figure corresponds to that of FIG. 2 and the corresponding description should therefore not be repeated.

It is recognized in the lower illustration that the cover elements 9 only partially cover the area outside the web PB ^* , are present in sections. They only reach a little way beyond the narrow web width PB ^* including the amount x (see FIG. 2 ) in the transverse direction. This results in a total of a multiple alternation of humectant 11, which is delivered here sectionally and the application medium. 5

In the unused area of the medium order, the application medium 5 is intercepted in the region of the web edge and returned to the working cycle via said collecting element and return channel 7.1.

Depending on the width of the cover 9 can be dispensed with a separation of the return or as at FIG. 2 described, a separation of the return done.

In FIG. 4 is a plan view of the coating device of the invention of FIG. 1 shown in a third variant.

In the picture below it is shown that also as in FIG. 2 a full coverage of the unnecessary media order with the cover 9 is present. A repetition of the description should therefore not be made.

But unlike the previous two variants is in the upper figure of the FIG. 4 a shortened doctor blade element 3, ie a shortened doctor blade 3.1, which is shortened to the narrow web width PB ^* , shown.

This easier-to-handle blade design is possible due to the full coverage with the cover 9.

This has the advantage that it can be dispensed with a full-surface wetting of the entire length L of the counter surface 4, for the purpose of avoiding dry running.

A separation of the medium return is not absolutely necessary, because less Humidifying agent 11 opposite to the variant in FIG. 2 , is present and therefore the coating medium 5 is also less diluted.

However, in order not to damage the mating surface or to counteract shrinkage of the roll cover, both ends of the doctor blade 3.1 are provided with a rounding 12.

LIST OF REFERENCE NUMBERS

1

contraption

2

application unit

2.1

slot opening

3

doctor element

3.1

shortened doctor blade

4

counter surface

5

Order or. coating medium

6

train

7

collecting element

7.1

drip tray

7.2

Return channel

8th

deckles

9

cover

10

humidifying

11

humectants

12

rounding off

L

Length of the mating surface

PB

web width

PB ^*

narrow web width

Q

transversely

R

direction

x

Amount for cover

Claims (8)

Apparatus for coating a running paper, board or other fibrous web (6), comprising an application unit (2) with a transverse slot opening (2.1) extending in the transverse direction (Q) of the application unit (2), wherein the application unit (2) is a running one Counter surface (4 is assigned and having at least one Formatbegrenzer (8) for setting a desired width of the coating or zone of the order, wherein the at least one Formatbegrenzer (8) on the application unit (2), for example, in the slot opening (2.1) is arranged
characterized in that
at least one cover element (9) is provided, which seen in the radial direction between slot opening (2.1) of the application unit (2) and the web to be coated (6) and seen in the transverse direction (Q), a range between Formatbegrenzer (8) and a minimum Web width (PB ^* ) at least partially covered and that in addition at least one moistening device (10) for dispensing a moistening agent (11) for moistening the counter surface (4) is present. Device according to claim 1,
characterized in that
the order unit (2) a doctor element (3, 3.1) is arranged downstream. Device according to claims 1 and 2,
characterized in that a collecting element (7) between the application unit (2) and the doctor element (3) is provided. Device according to claim 3,
characterized in that the collecting element (7) is a collecting plate (7.1) and a return channel (7.2) and both components (7.1, 7.2) are executable split. Device according to claim 2,
characterized in that the doctor element (3) is greater than the width (PB, PB ^* ) of the web (6) and the mating surface (3). Device according to claim 2,
characterized in that the doctor element (3, 3.1) is smaller than the width (L) of the counter surface (4) and substantially the width (PB ^* ) of the web (6). Device according to claim 6,
characterized in that the doctor element (3) is designed as a blade (3.1) and is provided at its ends with rounded portions (12). Device according to at least one of the preceding claims,
characterized in that the application unit (2) is a per se known free-jet commissioned work or a per se known curtain applicator.

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