EP2017012A2 - Curtain coating machine - Google Patents

Abstract

The curtain coating machine has a curtain head (1a) for dispensing pasty application medium (ta) for the curtain layer. Another curtain head (1b) is provided for dispensing another pasty application medium for another curtain layer. A device is provided for adjusting the application width for the curtain head, which is arranged such that the application width is provided below the curtain head for the curtain layers.

Description

The present invention relates to a curtain coater for coating a running paper, board or other fibrous web, comprising a first curtain head for dispensing a first coating medium for a first curtain layer and a second curtain head for dispensing a second coating medium for a second curtain layer, the first curtain head upstream of the second curtain head and both curtain heads emit their curtain layers downwardly, and having an inclined guide plate which is disposed below the curtain heads and which receives the curtain layers discharged from the curtain heads and flow down along its slope, the curtain layers of a curtain guide from falling on the surface of the web to be coated (w) in the form of a curtain.

Printing paper, such as for catalogs and coated paper, which is used, among other things, for pressure-sensitive paper or thermal paper, is prepared by applying a coating to the surface of the web (base paper) with a coater and then drying it. Machines that perform the coating of the strokes in this way are called coaters. In these conventional coating machines, there have been mainly doctor blade coaters, doctor blade coaters such as a round bar, or a blade or air knife machines to which the post-metering method is applied. In this first the line is applied in a more than necessary amount on the web, and then stripped with the said doctor element (metered) or blown off with an air knife. However, there are problems with the painting Redispensing the problems that penetrates deep into the web by the pressing force of the doctor blade or by the liquid pressure when applying the stroke on the web of the stroke, or that the maintenance costs are high due to the wear of the doctor element.

Thereupon, in recent years, more and more curtain coating machines have been used in general, in which the curtain layer is discharged from the curtain heads (chambers with nozzles) and thus the web is coated. Curtain coaters have long been used for photographic paper, but because of the instability of the curtain layer due to the trapping of air, bubbles trapped in the line at high speeds, or lack of mechanical accuracy, the stroke was not stable, so it was not suitable for the papermaking were used.

The curtain coater, however, in contrast to the conventional Nachdosiermethoden no wearing parts such as doctor blade or rods. As a result, the maintenance is simple, the amount of coating can be adjusted easily and with high accuracy, the operability is good and also the effect of the surface improvement for a covering coat to be applied is high. Etc.

Often, it is required that the web be coated with two or more layers. In such cases, two curtain heads are placed one behind the other at the top of the moving web and the two-layer stroke is formed by letting the applied curtain down onto the top of the web.

With such a curtain-type coating machine, if the speed at which the web travels is low (eg, 120 m / min), as in a film of photos, a coating of two will be formed Layers normally formed, because there is no great difference in the transport speed between lowering the line curtain and the transport speed of the film.

However, when this curtain-type coating machine is used for paper webs, the webs are transported at a high speed of 300 to 2000 m / min, so that a large difference in speed results because the lowering speed of the curtain is about 180 m / min. In such a case, the curtain forming the lower layer arrives wet on the dry surface of the web. The friction factor between the two is relatively large. The web surface is pulled uniformly and normally, as a first layer (lower layer), a uniform coating without unevenness is formed.

However, if the line curtain forming the top layer is wet on the wet surface of the first layer coating, the friction factor therebetween will be low and slippage will occur. The surface of the coating of the first layer can not be pulled well, causing bumps. It can also happen that the coating of the second layer (upper layer) does not form normally.

In the Japanese patent application 2006-249611 a suitable solution was disclosed. This is in FIG. 4 described.

FIG. 4 shows a part of the side view of the coating device. Like in the FIG. 4 is shown, a curtain coater for two layers is provided. It has two curtain heads 1a, 1b, which output the lines ta, tb, which flow in the slits da, db, respectively directed downwards. In addition, an inclined guide plate 2 is present, which the strokes ta, tb - issued by the two

Curtain heads 1a, 1b- in each case downwardly in turn on the slope 2a slide, these lines or layers are stacked with the movement on the slope 2a of the guide plate 2 in turn and from the downward tear-off edge of the curtain guide 2b as line curtains ca, cb moved to the surface of the web w. In this way, a line with two layers, sa (lower layer), sb (upper layer) are formed on the surface of the transported web w. The arrow indicates the direction of movement of the web w.

If thermal paper is to be produced with the curtain coater described here, where two application layers are necessary, namely a heat-sensitive layer and then a protective layer, this paper thus treated is smoothed after being coated and dried by a cloth press roller. However, if the coating width of the heat-sensitive layer is narrower than the coating width of the protective layer, the heat-sensitive layer comes into direct contact with the cloth press roller, thus contaminating the roll and thus posing an obstacle to operation. Therefore, it is necessary that the width of the Protective layer is wider than the line width of the heat-sensitive layer, and that the heat-sensitive layer is completely covered by the protective layer.

In such a coating machine for the production of thermal paper, there may also be cases in which the width of the web w to be spread is changed. In such cases, the width of the stroke ta applied by the curtain head 1a for the heat-sensitive layer stroke must be changed in accordance with the width of the web w. In order to change the width of the stroke ta, which is output from the curtain head 1a, in accordance with the output width is a slot on both sides of the slot there, from the the dash ta flows inside the curtain head 1a, pushed in, or there is a sliding lid inserted at both ends of the slot there.

If this is done by means of a slot, the machine has to be stopped in order to change the slot, but the stop results in a loss of productivity, and it also means that the slot to be replaced is firmly seated and can not be removed. If a sliding lid is used, the machine does not have to be stopped, but after long use it settles down and can not be moved, so that the line emerges from the gap between the slot and lid, and it becomes technically difficult. To insert the lid, since the width of the gap is narrow at 0.3 to 0.5 mm.

On the other hand, with respect to the curtain head 1b for the protective layer and the width of the stroke tb output from the curtain head 1b, it is not necessary to change, but should simply be outputted over the entire width, even if the width the web w changes. If the width of the line 1 b, which is output from the curtain head 1 b, wider than the width of the web w, the part of the stroke tb, which is wider than the web w in a paint trough, which falls below the course of the web w is provided and is collected there. This order type is called overboard.

The invention is therefore based on the object of specifying a curtain coater in which the disadvantages of the prior art do not occur.

According to the invention the object is achieved with the characterizing features of claim 1 such that a device for adjusting the Application width is provided for the first curtain layer arranged to be below the first curtain head for the first layer and associated with the lateral upper portion of the guide plate such that a central portion of the first curtain layer dispensed from the curtain head of FIG lateral parts of the same layer is separable, whereby the middle part slides down on the surface of the guide plate and the lateral parts flow in the opposite direction as the flow of the middle part.

At desired varying widths of one of the layers (eg, a heat-sensitive layer), the width of this line dispensed from the curtain head for that layer need not change but is output across the entire width and into a middle one after dispensing Split part and part at both ends. The middle part then gets on the track, whereas the two side parts are collected. Thereby, the technical difficulties in the case of changing widths of the bar, which is released from the curtain head for the first layer, are solved. At the same time, retraction (narrowing of the width with simultaneous increase in thickness by this proportion), which occurs at the edges of the line due to surface tension of the application medium, is avoided.

Further advantageous embodiments of the invention will become apparent from the dependent claims.

The effect and operation of the present invention are as follows. The stroke of the first applied application medium, which is output from the upstream curtain head downwards over the entire width, by a pair of device for adjusting the stroke width, which are provided directed downward, in a middle part and in a part at both Split ends. That is, the part meets on both sides of this first layer (on the web the lower layer) on the partition plate, which has a gradient opposite to the guide plate, flows on the partition plate in the opposite direction downwards and is collected by the ink pan. On the other hand, the middle part which exits as it flows downward, impinges on the guide plate near the upper edge and flows along the slope thereof and moves from the lower edge of the downwardly directed curtain guide to the surface of the web as a curtain , In this case, for the middle part of the stroke, the areas of the inside of the edge guide on the plate of the device for adjusting the stroke width, the area of the

Inside the auxiliary guide and the surface of the inside of the partition plate a uniform vertical guide plane. The side surfaces of the middle part are guided by these vertical guide surfaces and thus arrive on the surface of the guide plate. On the slope of the flow of the stroke of the first layer is guided by the surface of the inside of the edge guide on the guide plate. As a result, no retraction is caused to the lower edge of the edge guide on the plate.

On the slant of the guide plate, immediately after the flow of the first layer stroke on the slant of the guide plate separates from the lower edge of the edge guide, the impact position of the slash of the second applied sliver layer discharged from the second curtain head may occur. on the guide plate, only slightly (eg, 1 to 2 mm) of the lower edge of the edge guide is downstream of the guide plate so that the flow of the first layer stroke on the guide plate slope is restricted by the guide plate and the second stroke flow. This is done at the time it decides whether or not it will pull in, so there is no catchment in the flow of the first layer. At both ends of the flow of the stroke of the second Although there may be layers of edge thickening on the surface of the web, they can be cut off by a knife and no problems are caused.

Further, the point of impact of the second layer emitted by the second curtain head may also be somewhat upstream (e.g., about 1 to 2 mm) from the lower edge of the edge guide on the guide plate on the guide plate. In this case, under no circumstances does the problem of drawing in the flow of the first stroke occur.

The stroke for the first layer is outputted over the entire width, divided into a middle part and a part at both ends after dispensing, the middle part is applied to the web, and the part at both ends is collected.

Thus, it is not necessary, as in the prior art, to change the width of the dispensed from the first curtain head stroke, in both ends of the slot through which flows the respective application medium, inside the curtain head so-called format slide or insertions or on insert a movable lid at both ends of the slot, so that the interior of the curtain head is kept clean and at the same time the accuracy can be maintained. Further, it is also possible to automatically perform the positioning of the web and curtain of the stroke of the first layer by detecting the lurching of the web and the associated movement of the adjustment device of the stroke width. In addition, this has the effect of preventing the drawing-in which occurs at the edges of the first stroke due to the surface tension of the medium.

The present invention is particularly suitable for the production of Thermal paper. As the first layer, a heat-sensitive layer is applied by means of the first curtain head. This is the surface of the web completely covered by the second applied layer, the protective layer, on the whole width. This is true even if the width of the protective line output from the curtain head for the protective layer is larger than the largest width between the areas on the inside of the bar width adjusting device.

Advantageously, there is no direct contact of the heat-sensitive layer with the cloth press roller, and thus the problem of contamination of the roll surface does not occur.

The invention of an embodiment will be explained in more detail below.

• Figur 1(A) : eine Abbildung des Zustands, in dem bei einer Herstellungsvorrichtung für Thermopapier kein Schutzstrich ausgegeben wird, in einer Draufsicht, bei der zum leichteren Verständnis der Vorhangkopf für die Schutzschicht nicht dargestellt ist,
• Figur 1(B) : eine Seitenansicht (Schnittzeichnung entlang Pfeile B-B).
• Figur 2(A) : eine Abbildung des Zustands, in dem bei der Herstellungsvorrichtung für Thermopapier der Schutzstrich ausgegeben wird, in einer Draufsicht, bei der zum leichteren Verständnis der Vorhangkopf für die Schutzschicht nicht dargestellt ist,
• Figur 2(B) : eine Seitenansicht (Schnittzeichnung entlang Pfeile B-B),
• Figur 2(C): eine Querschnittszeichnung (Schnittzeichnung entlang Pfeile C-C), welche die Beziehung zwischen wärmeempfindlicher Schicht und Schutzschicht auf der Oberfläche der Bahn darstellt,
• Figur 3 : ein Grundriss, welcher die Beziehung zwischen Unterkante der Kantenführung auf der Platte und des Auftreffpunkts des Schutzstriches, welcher von dem Vorhangkopf für die Schutzschicht ausgegeben wird, auf der Führungsplatte darstellt.

Show it:

• FIG. 1 (A) : Imaging in which at a manufacturing apparatus for thermal paper no guard bar output of the state, in a plan view in which is not shown for easier understanding of the curtain head for the protective layer,
• FIG. 1 (B) Is a side view (sectional view along arrows BB).
• Figure 2 (A) : A picture in the output in the production apparatus for thermal paper of the guard bar of the state, is in a plan view, in the not shown for ease of understanding of the curtain head for the protective layer,
• FIG. 2 (B) Is a side view (sectional view along arrows BB),
• Figure 2 (C) is a cross-sectional drawing (cross-sectional view along arrows CC) showing the relationship between heat-sensitive layer and protective layer on the surface of the web.
• FIG. 3 : A plan view, which represents the relationship between the lower edge of the edge guide to the plate and the impact point of the guard bar, which is output from the curtain head to the protective layer on the guide plate.

Incidentally, in these figures, the same parts are denoted by the same designations as in FIG Figure 4 in which the conventional technique is described.

In these figures, 1a denotes the curtain head for a first coating medium ta for a first layer ca, i. for a heat-sensitive layer sb. The curtain head 1a is arranged upstream of a second curtain head 1b for a second application medium tb or for a second layer cb or for a protective layer sb.

Denoted by 2 is a guide plate which receives the media originating from these curtain heads 1a, 1b on their bevel 2a and allows them to flow down along the bevels 2a. From a downwardly directed lower edge (tear-off edge) of the curtain guide 2b, the media ta, tb reach the surface of the web w as a falling line curtain c.

The upper edge of the guide plate 2 has a bent portion 2c with a gradient which is reversed to the slope 2a along which the bar to be applied flows.

With a device 9 for adjusting the stroke width is designated. The Device 9 is disposed below the curtain head 1 a for the heat-sensitive layer and is arranged symmetrically to the surfaces (vertical surfaces including the center line c1 of the coating machine) at the two ends of the upstream guide plate 2, the position of which is adjustable in width and the surface of a to the gradient of the guide plate 2 has opposite gradient on which the middle part tac of the stroke ta of the heat-sensitive layer discharged from the curtain head 1a for the heat-sensitive layer on the guide plate 2 flows, and on which the part of both ends tae of first coating medium ta of the heat-sensitive layer, which is discharged from the curtain head 1a for the heat-sensitive layer on the guide plate 2 and flows on the surface thereof in the direction opposite to the flow on the guide plate 2.

The bar width setting device 9 has a pair of edge guides 3 extending downward from the upper edge of the guide plate 2, parallel to the inner surface, and also parallel to the center line c1 of the coating machine. The edge guides 3 bear against the surface of the guide plate 2 and are pointed at their lower edge. In addition, a parallel pair of auxiliary guides 4 is provided, which are fixedly mounted in the region of the upper edges of the edge guides 3 of the relevant plate and which are seen from the outside wedge-shaped. Their surface has a gradient which is opposite to the gradient of the guide plate 2. In addition, a parallel pair of partition plates 5 are provided, which are fixedly mounted on the surface of the respective auxiliary guides 4 and whose surface has a gradient which is the same as the gradient of Surface of the auxiliary guides 4. In the area of the lower edge 3a of the edge guides 3 on the guide plate whose thickness is reduced, as in Figure. 1 and 2 is shown. The partition plate 5 is as shown in the figures bent at the edge downwards.

The surfaces of the inner sides of the edge guides 3 on the guide plate, the surfaces of the inner sides of the auxiliary guides 4 and the surfaces of the inner sides of the partition plate 5 form, as in FIG. 1 and 2 represented, a uniform vertical guide surface 9a. The stroke tae flowing on the partitioning plate 5 of the bar width adjusting device 9 is collected by the ink fountain 7.

6 denotes a device for positioning. With this device 6, the adjustment of the position of the device 9 for adjusting the stroke width is made in the transverse direction. The positioning device 6 consists of bolts 6a which are rotatably mounted on the side surfaces of the outsides of the edge guides 3 on the plate and consists of nut members 6b which are positively connected to the respective bolts 6a and at the same time fixedly mounted on the end surfaces of the guide plate 2 are.

The width of the coating medium tb discharged from the curtain layer head 1b for the protective layer is larger than the largest width between the surfaces 9a of the inner surfaces of the bar width adjusting device 9.

The impact position X of the second medium tb, which is output from the second curtain head 1b for the protective layer, is on the guide plate 2, as in FIG FIG. 3 represented something (eg 1 to 2 mm) in front of the lower edge 3a of the edge guide 3 on the. Plate, or something (eg 1 to 2 mm) behind it. Designated at 8 is a pair of edge guides parallel to each other, which are provided to guide the part of the curtain c which extends from the curtain guide 2b to the web w. Thus, another guide surface is present, the one Constriction of the curtain c prevented.

Hereinafter, the operation of the embodiment of the present embodiment will be explained.

The line ta of the heat-sensitive layer, which is discharged from the curtain-side head 1a for the heat-sensitive layer downwards over the entire width, is divided into a middle part tac and a unit by the bar width adjusting device 9 arranged below Part tae divided for both sides. That the part tae for both sides of the discharged medium ta of the heat-sensitive layer strikes the partition plate 5 which has a gradient opposite to the guide plate 2, flows downward on the partition plate 5 and is caught by the ink pan 7. On the other hand, the middle part tac of the discharged stroke ta is directed downward as it is, hits in the region of the upper edge of the guide plate 2, flows down along its slope 2a, and moves from the downwardly facing curtain guide 2b to the line curtain c Surface of the railway w. In this case, for the middle part tac of the stroke ta, the area of the inside of the edge guide 3 on the plate of the device for setting the stroke width, the area of the inside of the

Auxiliary guide 4 and the surfaces of the inside of the partition plate 5 a uniform vertical guide surface 9a, so that the side surfaces of the central part tac is guided by this vertical guide surface 9a and so arrives on the slope 2a of the guide plate 2. On the slope 2a, the flow of the stroke tac of the heat-sensitive layer is passed through the surface of the inside of the edge guide 3 on the plate. Consequently, up to the lower edge 3a of the edge guide 3 on the plate no retraction caused.

In the flow of the medium for the heat-sensitive layer on the Slant 2a of the guide plate 2 occurs initially immediately after leaving the lower edge 3a of the edge guide 3 on the plate to retract. But the impact position X of the coating medium ta on the guide plate 2 is slightly (eg 1 to 2 mm) in front of the lower edge 3a of the edge guide 3 on the plate or something (eg 1 to 2 mm) behind it, so that the flow of the medium ta on the slope 2a of the guide plate 2 before it is determined whether it comes to a retraction or not, concentrated by the guide plate 2 and the flow of the stroke tb of the protective layer. As a result, there is ultimately no pulling in with edge thickening of the first layer ta or approx

It is possible to automatically perform positioning of the web w and the curtain ca of the medium ta for the heat-sensitive layer by recognizing the lurching of the web and the related movement of the adjusting device 9 of the line width. In addition, this has the effect of preventing the entanglement caused by the surface tension at the edges of the heat-sensitive layer medium ta.

Since the heat-sensitive layer sa on the surface of the web w is completely covered completely by the protective layer sb (even if the width of the stroke tb output from the protective-layer curtain head 1b is larger than the largest width between the surfaces 9a on the inside of the device for adjusting the line width 9), there is no direct contact of the heat-sensitive layer sa with a cloth press roller present in the manufacture of the thermal paper web and thus the problem of contamination of the roller surface does not occur.

The present invention is not limited to the configuration in the above-described embodiment, but it may be changed. as long as the main contents of the invention are not violated. For example, a combination of bolts 6a and nut member 6b for the positioning device 6 has been described, but for example, a combination with a rack or a linear motor may also be used.

LIST OF REFERENCE NUMBERS

1

Curtain coater

1 a

Curtain head for the heat-sensitive layer

1 b

Curtain head for the protective layer

2

guide plate

2a

slope

2 B

curtain guide

2c

bent part

3

Edge guide on the guide plate

3a

lower edge

4

auxiliary guide

5

Dividing or separating plate

6

positioning device

6a

bolt

6b

nut element

7

paint tray

8th

edge guide

9

Device for adjusting the stroke width

9a

vertical guide surface

c

curtain

ca

first curtain layer

cb

second curtain layer

there

application slot

db

application slot

Sat.

Lower class

sb

upper layer or protective layer

ta

first application medium

tb

second application medium

tac

middle part

tae

lateral part

X

landing

Claims (14)

Curtain coater (1) for coating a running paper, cardboard or other fibrous web (w), comprising a first curtain head (1a) for dispensing a first application medium (ta) for a first curtain layer (ca) and comprising a second curtain head (1b) for dispensing a second coating medium (tb) for a second curtain layer (cb, sb), wherein the first curtain head (1a) precedes the second curtain head (1b), and both curtain heads (1a, 1b) retract their curtain layers (ca, cb) directed downwards, and comprising an inclined guide plate (2), which is arranged below the curtain heads (1a, 1 b) and receives the curtain layers emitted curtain layers and flow down along its slope (2a), wherein the curtain layers (approx , cb) fall from a curtain guide (2b) onto the surface of the web (w) to be coated in the form of a curtain (c),
characterized in that
a device (9) for adjusting the application width for the first curtain layer (ca) is provided, which is arranged so that it is located below the first curtain head (1a) for the first layer (ca, sa) and the lateral upper region of Guide plate (2) is assigned, so that a central part (tac) of the first curtain layer (ca), which is discharged from the curtain head (1a) is separable from lateral parts (tae) of the same layer (ca), whereby the middle part (tac ) slides down on the surface of the guide plate (2) and the lateral parts (tae) flow in the opposite direction as the flow of the middle part (tac). Curtain coater (1) according to claim 1,
characterized in that
the device (9) for adjusting the application width of the first application medium (ca) comprises a pair of edge guides (3), a pair of auxiliary guides (4) and a pair of partition plates (5), wherein in each case the surface of the inside of the edge guide (3) Face of the inside of the auxiliary guide (4) and the surface of the inside of the partition plate 85) forms a uniform, vertical guide surface (9a) for the middle part (tac) of the first application medium (ca9 or for the first layer (sa). Curtain coater (1) according to claim 1 or 2,
characterized in that
the edge guides (3) in each case rest on the side of the guide plate (2) and extend downwards from the upper region, the inner sides of the edge guides (3) being parallel to one another and also parallel to an imaginary center line (c1) of the curtain coater (1 ) are. Curtain coater (1) according to at least one of the preceding claims,
characterized in that
the edge guides (3) each have a pointed lower edge. Curtain coater (1) according to at least one of the preceding claims, characterized in that
the auxiliary guides (4) are placed on the upper edges of the edge guides (3) and firmly connected thereto. Curtain coater according to at least one of the preceding claims,
characterized in that
the surfaces of the lateral edge guides (3) are inclined in the same direction as the guide plate (2). Curtain coater according to at least one of the preceding claims,
characterized in that
the lateral partition plates (5) are respectively fixedly mounted on the surface of the respective auxiliary guides (4), the surfaces of the auxiliary guides (4) being inclined in the same direction as the surfaces of the auxiliary guides (4). Curtain coater according to at least one of the preceding claims, characterized in that
the partition plates (5) and the surfaces of the auxiliary guides (4) are inclined in opposite directions to the edge guides (3) and the guide plate (2). Curtain coater according to at least one of the preceding claims,
characterized in that
below the dividing plates (5) a collecting trough (7) is arranged, which absorbs the lateral parts (tae) of the first application medium (ca), which flow away from the dividing plates (5), these lateral parts opposite to the flow direction of the middle application medium part (tac ) on the guide plate (2). Curtain coater according to at least one of the preceding claims,
characterized in that
for adjusting the application width of the application medium, a positioning device (6) consisting of a screw bolt (6a) and a nut element (6b) is provided, wherein each of the bolts (6a) on the lateral outer surface of the edge guide (3) and above the guide plate (2) is rotatably mounted, and wherein the nut member (6b) with the respective bolt (6a) is positively connected, and at the same time on the side surface of the Guide plate (2) is mounted. Curtain coater according to at least one of the preceding claims,
characterized in that
a second pair of auxiliary guides (8) is provided for guiding the curtain (c) extending from the curtain guide (2a) to the surface of the web (w). Curtain coater according to at least one of the preceding claims,
characterized in that
the first application medium (ta) forms a heat-sensitive lower layer (sa) and the second application medium (tb) forms an upper protective layer (sb) on the fibrous web (w). Curtain coater according to at least one of the preceding claims,
characterized in that
the protective layer (sb) covers the heat-sensitive layer (sa) larger than the width of the first coating medium (ta) between the parallel vertical guide surfaces (9a). Curtain coater according to at least one of the preceding claims,
marked by
their use in the production of thermal paper.

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