EP1040227B1 - Slit nozzle for coating strips of material, especially paper or board strips, with a pigment coating - Google Patents

Abstract

A slot nozzle for coating webs of material, for example, paper, paperboard, cardboard, with a flowable coating substance, for example, a pigment coating, has a slot shaped outlet channel to which a distribution chamber extending over the width of the web is connected. A plurality of supply conduits are connected to the distribution chamber in spaced relationship across the width of the web and the length of the outlet channel and each supply conduit has a valve for adjusting the volume flow of the coating liquid. A respective diffuser is provided between each supply conduit and the distribution chamber and widens in the direction of the latter.

Description

Technical field

The invention relates to a slot nozzle for coating material webs, in particular paper or cardboard webs with pigment coating, with a slot-shaped outlet channel, which extends over the working width, and a distribution chamber extending over the working width to which the Outlet channel is connected.

State of the art

When coating material webs are known about the Working width extending slot nozzles used to a defined on the web Apply curtain or jet of coating material. For coating devices, who work on the principle of curtain painting Coater), the slot nozzle above the web will be transverse to the web running direction extending arranged. The coating material occurs in a free falling Curtain out of the nozzle and falls on the web. Such a slot nozzle The generic type is in EP 0 327 020-B1 in a coating device known, which is used for the production of photographic films. A procedure for Production of coating paper, with the pigment coating color in a free-falling Curtain applied to a paper web is known from EP 0 517 223-B1.

In the case of so-called free jet nozzle application devices, the slot nozzle is made up of two Lips formed from which a free jet of coating material is pressed against the web or - in the case of indirect application - is directed against a roller. The stake a slot nozzle as a free jet nozzle for coating paper webs is in DE 296 10 773-U.

Presentation of the invention

When coating paper or cardboard webs with a large width (for example 10 m), it is necessary to produce a very uniform jet or curtain of coating material over the working width. This is particularly difficult if small amounts (for example 10 ml / m ² ) of pigment coating ink are to be applied. Pigment coating colors tend to separate if there are different shear conditions in the flow. At the same time, it must be ensured that there are no disruptive deposits of pigments in the feed channels and the nozzle.

The invention is therefore based on the object of a generic slot nozzle to improve that it is able to run on large width paper or cardboard webs also small amounts of pigment coating ink under fluctuating conditions, z. B. fluctuating viscosity or changing order quantities, evenly Can be applied without interference across the working width.

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

The slot nozzle according to the invention offers the possibility of the flow conditions in the distribution chamber over the working width via the supplied volume flows influence.

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

With a distance between two feed channels of 100 mm to 1500 mm, preferably 500 mm to 800 mm, according to claim 2 ensures that the part of the distribution chamber supplied with coating material by a feed channel It is not too great that the transverse distribution in the chamber makes unacceptable flow differences occur.

The formation of the connection of a feed channel to the distribution chamber as Diffuser according to claim 3 causes the flow rate at Entry into the distribution chamber significantly reduced. This prevents the Brush paint from the walls and thus vortexes that lead to uneven flow conditions would lead.

Inclined diffusers connected to the distribution chamber according to claim 4 make it possible to use long diffusers with a low overall height and these on the to connect essentially straight supply channels fed from one side. There the coating color with high flow velocity within the feed channels is promoted, curvatures in the feed channels could be sensitive Coating colors lead to undesired segregation effects.

Brief description of the drawing

Figur 1

zeigt einen Längsschnitt durch eine Schlitzdüse nach der Erfindung.

Figur 2

zeigt einen Querschnitt entlang der Linie A-A von Figur 1.

Figur 3

zeigt einen Querschnitt entlang der Linie B-B von Figur 1.

Figur 4

zeigt eine Draufsicht von unten auf den Ausstrittsspalt.

Figur 5

zeigt im Querschnitt den Aufbau und die Arbeitsweise einer Schlitzdüse beim Einsatz als Vorhangdüse.

Figur 6

zeigt grob schematisch einen konstruktiv besonders einfachen Aufbau einer Schlitzdüse mit Kühlelementen an den Längsseiten.

Figur 7

zeigt grob schematisch den Querschnitt einer Schlitzdüse mit einer zweiten Verteilerkammer, die in einer Klimakammer angeordnet ist.

Figur 8

zeigt den Querschnitt einer alternativen Ausführungsform einer Schlitzdüse, die als Freistrahldüse ausgelegt ist.

The drawing serves to explain the invention on the basis of simplified exemplary embodiments.

Figure 1

shows a longitudinal section through a slot nozzle according to the invention.

Figure 2

shows a cross section along the line AA of Figure 1.

Figure 3

shows a cross section along the line BB of Figure 1.

Figure 4

shows a plan view from below of the outlet gap.

Figure 5

shows in cross section the structure and operation of a slot nozzle when used as a curtain nozzle.

Figure 6

shows roughly schematically a particularly simple construction of a slot nozzle with cooling elements on the long sides.

Figure 7

shows roughly schematically the cross section of a slot nozzle with a second distributor chamber, which is arranged in a climatic chamber.

Figure 8

shows the cross section of an alternative embodiment of a slot nozzle, which is designed as a free jet nozzle.

Ways of Carrying Out the Invention

The nozzles shown in the figures are used to apply pigment coating ink onto a paper or cardboard web B. The pigment coating ink is either applied directly the paper or cardboard web B or first applied to a roller, the then passes the film of coating color to web B.

The slot nozzle is used either as a curtain nozzle or as a free jet nozzle. When used as a curtain nozzle, it is across the web B across Working width arranged arranged, and the coating color occurs in a free-falling Curtain V out of it. The different ways of arranging one Slot nozzle as a curtain nozzle within a coating system for coating of paper or cardboard webs with pigment coating color and their mode of operation described in great detail in German patent application 197 16 647.4 which is expressly referred to.

When used as a free jet nozzle, a free jet S of coating color comes under pressure from the slot nozzle, which is directly against web B or - with indirect application - is directed against a roller. The free jet nozzle is usually in relation to the web B to be coated or the tangent to the roller to be coated so arranged that the liquid jet S at an acute angle to the direction of movement the web B or roller hits. The use of a free jet nozzle in a system for coating paper or cardboard webs with pigment coating ink described in detail in German patent application 197 19 128, to the is referred.

In the embodiment shown in Figures 1 to 5, the nozzle body the slot nozzle from two wall-shaped parts 1, 2 with one of the desired Working width corresponding length. In one long side of a part (in the example part 1) a longitudinal groove is incorporated, which after joining the two parts 1, 2 forms a distribution chamber 3. The two parts 1, 2 each face-ground Inner surfaces with which they are joined and using fastening screws 4 are held together.

One of the two transverse walls delimiting the distribution chamber 3 - in FIGS. 2 and 3 the lower transverse wall 5 - is of a slightly lower height than the other, upper Transverse wall 6 formed so that when assembling a distance from the wall part 2 remains in this area a slit-shaped, over the working width Extending outlet channel 7 to form, which is connected to the distribution chamber 3 and from which the coating color emerges. By the gap width of the outlet channel 7 to be able to adjust the working width differently in individual areas, the outlet channel 7 on the one hand from the inner surface of the wall part 2, on the other limited by an inserted bar 8, which on the inner surface of the lower Cross wall 5 is screwed by means of screws 9. The insert bar 8 has below the fastening screw 9 on its side facing away from the outlet gap 7 Side a longitudinal slot, so that a weak point 10 arises to be lower part can be bent to adjust the gap width. The lower part of the Insert bar 8 has the necessary distance for the required adjustment the inner surface of the transverse wall 5. The adjustment of the gap width of the outlet channel 7 is carried out by means of wedges arranged at regular intervals across the working width 11, which in a longitudinal groove of the lower transverse wall 5 parallel to the outlet channel 7 are movably arranged and support the insert bar 8 on its back. The Wedges 11 lay the distance of the insert strip 8 from the wall part 2 and thus the Gap width of the outlet channel 7 in their area. The setting of the position each wedge 11 is done by means of an adjusting screw 12. To the position of the Insert bar 8 on each wedge 11 are in the area between two wedges 11 each clamping screws 13 arranged, of which the insert bar 8 against the wedges 11 and thus can be clamped against the transverse wall 5. Keys 14 prevent a between the transverse wall 5 and the upper region of the insert bar 8 Shift of the insert bar 8 parallel to the outlet channel 7 when setting the Gap width. The inner surfaces of the transverse wall 5 and the insert strip 8 are preferred, of which the lower boundary wall of the distribution chamber 3 is formed, aligned with one another and inclined in the direction of the outlet channel 7 designed so that the coating color is led to the outlet channel 7. When using As a curtain nozzle, the width of the outlet channel 7 is between 150 µm and 600 µm, preferably between 250 µm and 350 µm. At the When used as a free jet nozzle, the width of the outlet channel is 7 700 µm to 1300 µm.

As a curtain nozzle, the height measured parallel to the outlet channel 7 is Distribution chamber 3 10 mm to 100 mm, preferably 20 mm to 60 mm. If the height is more than 20 mm, its width is less than its height. As a free jet nozzle the height of the distribution chamber 3 is 40 mm to 150 mm. The is preferably Width between 50% and 60% of the height.

The upper transverse wall 6 of part 1 has inlet openings at regular intervals 15, on which, as shown in FIG. 5, feed channels 16 for feeding Coating color are connected in the distribution chamber 3. The so on the Outlet channel 7 opposite side connected to the distribution chamber 3 Feed channels 16 have a connection distance between 100 mm and 1500 mm, preferably between 500 mm and 800 mm. The connection of one is preferred each feed channel 16 to the distribution chamber 3 formed as a diffuser, so due to the increasing flow cross-section the flow velocity at Entry into the distribution chamber 3 drops. The diffusers are each from the Opening 15 formed in the transverse wall 5 and a screwed-on diffuser part 17, to which a feed channel 16 is attached in each case.

The openings 15 and the diffuser part 17 are preferred Diffusers designed and arranged so that they are towards the side edge are connected to the distribution chamber 3 inclined to the vertical. The preferably inclined to one side - that is to say with feed channels 16 fed in parallel The diffusers are connected in such a way that a boundary wall (the left one in FIG. 1) Boundary wall) at an angle α between 0 ° and 90 °, preferably between 30 ° and 60 ° connected to the upper boundary wall of the distribution chamber 3 is, the opposite boundary wall of the diffuser at an angle β between 10 ° and 45 °. Furthermore, the boundary wall of the diffuser is on the Supply side immediately before connection to the distribution chamber 3 after curved outside to further enlarge the cross section and the radius of the To make the deflection as large as possible. In the exemplary embodiment, this is done by a corresponding curvature of the inlet side forming the last part of the diffuser Wall 18 of the inlet opening 15 causes. The boundary wall 18 designed in this way of the diffuser prevents the coating color from detaching from the walls and thus Eddies that would cause the coating color to separate.

The slot nozzle is closed by side plates 19 on its end faces. At the Use as a curtain nozzle is on each side immediately next to the outlet channel 7 downwardly extending guide element 20 arranged that a constriction counteracts the curtain V of coating color falling from the outlet channel 7. To prevent the curtain V from being torn off from the guide elements 20 each on the inner surface of each guide element 20 as a partial flow of coating color Contact liquid allowed to flow down, which is supplied via a supply channel 21 becomes.

As shown in FIG. 5, each feed channel 16 has a device 22 Setting the volume flow to. To prevent deposits of pigments in the Exclude device 22, hose clamp valves are preferred for the Volume flow setting used. Alternatively, the use of Diaphragm valves possible. In addition, each feed channel contains a measuring device 23 to determine the current volume flow so that it is individually regulated can be; z. B. inductive or ultrasonic volume flow meters 23rd

In Figure 6, an embodiment of a nozzle is shown schematically, the construction is particularly simple. This structure is useful if there are no control elements Cross profile control are required, ie the width of the outlet channel 7 over the Working width does not have to be adjustable differently.

As in the embodiment according to FIGS. 1 to 4, the nozzle body is made of two Parts 1, 2 assembled, each having a flat ground inner surface. In one part - the left part 1 in Figure 6 - is the distribution chamber 3 as a longitudinal groove incorporated. In contrast to the embodiment according to FIGS. 1 to 4, the Inner surfaces of the two transverse walls 5, 6 designed in alignment. When putting it together is a flat material 24, z. Legs Foil inserted, the thickness of the desired gap width of the outlet channel 7 equivalent. So when assembling the two parts 1, 2 in the area below the distribution chamber 3, the lower transverse wall 5 on the thickness of the flat material 24 held appropriate distance from the inner surface of part 2. It forms the outlet channel 7 with the desired gap width.

FIG. 7 shows an embodiment with one between the first distributor chamber 3 and the outlet channel 7 arranged second distribution chamber 25. Between the first distribution chamber 3 and the second distribution chamber 25 is located additional flow channel 26, which further smoothes the flow causes.

With large working widths, locally different temperatures lead to deformation, that affect the outlet channel 7. To counteract these deformations is on one or both longitudinal walls of the nozzle body of the slot nozzle a number of heating or cooling elements 27 are arranged, as shown in FIG. The heating or cooling elements 27, for example Peltier elements, resistance wires etc. are arranged at a distance of 100 mm and more across the working width, Their heating or cooling capacity can be regulated individually in order to target individual Areas. Alternatively or in addition, it is possible to complete the whole To arrange slot nozzle in a climatic chamber 28, as shown in Figure 7. In the The climatic chamber becomes a temperature-controlled medium, for example water or air introduced via a feed line 29 to the temperature of the nozzle at a desired Keep value constant.

In Figure 8 is the cross section of a slot nozzle when used as a free jet nozzle shown, by means of which the coating color is supported on a counter-roller 30 Paper or cardboard web B is applied.

The slot nozzle also has a slot-like shape when used as a free jet nozzle Exit channel 7, which extends across the working width. The slit-shaped Exit channel 7 is delimited by two lips 31, 32, one of which - in Embodiment, the lip 31 on the outlet side - by means of a series of adjusting elements 33 differently adjustable in zones from one another to their other lip 32 is to set a uniform cross profile. The width of the outlet channel 7 is when used as a free jet nozzle set to the mentioned 700 µm - 1300 µm.

The distribution chamber 3 is delimited by two side walls 1, 2, which on the Inlet side are screwed to a transverse wall 34 by means of screws 35, of which they are kept at the desired distance for the chamber width. At the One side of the lips 31, 32 is attached to each side wall 1, 2 on the outlet side.

In longitudinal section, the structure of the free jet nozzle essentially corresponds to that in FIGS Figures 1 and 5 shown slot nozzle: There are also at least two Feed channels 16 connected to the distribution chamber 3, each having a device to adjust the volume flow. The connection distance of the feed channels 16 is also 100 mm to 1500 mm, preferably 500 mm to 800 mm. As well is the connection of a feed channel 16 to the distribution chamber 3 as a diffuser formed, the diffusers towards the side edge under the at Embodiment according to Figures 1 to 5 angles inclined to the Distribution chamber 3 are connected.

Claims (15)

1. Slot nozzle for coating material webs (B), especially paper or board webs, with pigmented coating colour,

   having a slot-like outlet channel (7) which extends over the working width, and

   a distribution chamber (3) which extends over the working width and to which the outlet channel (7) is connected,

   characterized in that at least two feed channels (16) are connected to the distribution chamber (3) and each have a device (22) for setting the volume flow of coating material supplied.
2. Slot nozzle according to Claim 1, characterized in that the feed channels (16) are arranged on the side opposite the outlet channel (7), and the connection distance between two feed channels (16) is 100 mm to 1500 mm, preferably 500 mm to 800 mm.
3. Slot nozzle according to Claim 1 or 2, characterized in that the connection of a feed channel (16) to the distribution chamber (3) is designed as a diffuser.
4. Slot nozzle according to Claim 3, characterized in that the diffusers are connected to the distribution chamber (3) such that they are inclined with respect to the vertical in the direction of the lateral edge.
5. Slot nozzle according to Claim 4, characterized in that a boundary wall of the diffuser is connected to the distribution chamber (3) at an angle α between 0° and 90°, preferably between 30° and 60°, and the opposite boundary wall is connected to the distribution chamber (3) at an angle β between 10° and 45°.
6. Slot nozzle according to one of Claims 1 to 5, characterized in that a pinch valve for setting the volume flow is integrated into each feed channel (16).
7. Slot nozzle according to one of Claims 1 to 6, characterized in that a row of heating or cooling elements (27) is arranged on one or both longitudinal walls of the nozzle body.
8. Slot nozzle according to one of Claims 1 to 7, characterized in that it is arranged in an air-conditioned chamber (28).
9. Slot nozzle according to one of Claims 1 to 8, characterized in that the nozzle body is assembled from two parts (1, 2) which each have a flat-ground inner surface, the distribution chamber (3) being machined into one part as a groove and, during assembly, a flat material (24) being inserted in the region above the distribution chamber (3), holding the region underneath the distribution chamber (3) at the desired distance, in order to form the outlet channel (7).
10. Apparatus for applying a pigmented coating colour to a paper or board web (B), characterized in that above the web (B) there is arranged a slot nozzle which extends transversely with respect to the web running direction and from which the coating colour is applied to the web (B) in a free-falling curtain (V), the slot nozzle having the features of one or more of Patent Claims 1 to 9.
11. Apparatus according to Claim 10, characterized in that the outlet channel (7) of the slot nozzle has a gap width of 150 µm to 600 µm, preferably 250 µm to 350 µm.
12. Slot nozzle according to Claim 10 or 11, characterized in that the distribution chamber (3) has a height measured parallel to the outlet channel (7) of 10 mm to 100 mm, preferably 20 mm to 60 mm.
13. Apparatus for applying a pigmented coating colour to a paper or board web (B), characterized in that on the web (B) there is arranged a slot nozzle extending transversely with respect to the web running direction and according to Claims 1 to 9, from which the coating material emerges under pressure in a free jet (S).
14. Apparatus according to Claim 13, characterized in that the outlet channel (7) of the slot nozzle has a gap width of 700 µm to 1300 µm.
15. Apparatus according to Claim 13 or 14, characterized in that the distribution chamber (3) has a height measured parallel to the outlet channel (7) of 40 mm to 150 mm.

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