EP1598115B1 - Curtain coating apparatus - Google Patents

Abstract

Curtain coater has caper head (3) with slot (s2) at edge which is broadly framed than the other part of slot (s1). The widened slot is arranged in a distance from the edge side of the caper head. Broader slot has different shape such as rectangle, circle or oval. The caper head is built up from two caper bodies (3b). The broader part of the slot has a width dimension double of the other slot. The slots are provided at the caper head for track spacing purpose.

Description

The invention relates to a curtain coating with a coating head from which a coating color from a slit provided on the slot from above on a running underneath web, in particular paper or cardboard, falls and forms a coating curtain, which on one side of the aforementioned path arrives.

Coated papers such as catalogs, leaflets, thermal papers or automatically canceled tickets are made by applying a coating to the surface of a sheet of raw paper.

Machines for applying these coating colors are generally referred to as brushing machines, and those coating units which apply coating color to this web from a position above the web, which consists, for example, of paper or cardboard, are referred to as curtain coater.

Um, as in Fig. 6 (a) For example, in order to apply coating paint of predetermined thickness to the top of the web, the paint on the curtain head body 101 is delivered from the curtain coater 100 from above with respect to the conveyed web (not shown) so as to be perpendicular to the paper plane in FIG Fig. 6 (a) forms a curtain tc.

In this curtain coating machine 100, in general, in the case of curtains, tc occurs at a low flow rate (from 6 to 7 l / min / m width and less) the problem on that, as in Fig. 6 (b) shown, due to the inwardly acting surface tension, the edge regions ce of the curtain tc are drawn inwards, whereby the curtain tc of the coating color t becomes unstable.

To solve this problem are in the case of in Fig. 7 shown curtain coaters 200 at the two ends of the (not shown) slot, which is the discharge opening for the coating color in the head body body 201, guide rods gb or plates provided. With the aid of these devices, the curtain tc formed by the coating color t is guided and the destabilization of the curtain tc is avoided.

As a publicly available document describing a technique related to the present application, Japanese Laid-Open Patent Publication No. Hei JP-A 8-1061 known.

As previously stated, in curtain coating units 100, in those instances where the flow rate of the dispensed coating paint t is low, there is generally the problem that the edge portions ce of the curtain tc are drawn inwardly, destabilizing the curtain tc of the coating color t leads.

At even lower coating color flow rates, the curtain tc becomes uneven and becomes rainy. In this case, the maintenance of the specified strike performance is considerably more difficult.

The coating color t must always flow with a certain minimum flow rate, so that this deficiency can be eliminated. This results in the disadvantage that actually unnecessary coating color t is consumed.

In long-term operation, the curtain coating unit 200 equipped with guide rods or plates also causes coating color t to adhere to the guide rods gb or plates and solidify there after drying. As a result, the curtain tc in disorder and the leadership functionality is lost.

At the beginning of the coating application, there is also interference between the guide rods gb or plates on the one hand and the (not shown) paint tray in which the coating color is collected. As a result of this, the curtain tc of the coating color t becomes disadvantageously disordered.

The use of guide rods gb or plates also have the disadvantage that they or the like in the execution of maintenance. to disturb. They thus lead to a decline in labor productivity.

From the US-A-5902648 is a generic curtain coating known, wherein the provided at the coating head slot for the coating color extends to outside of the object to be painted, and the ends of the slot are formed wider. As a result, a stabilization of the coating color curtain is made possible.

In view of this situation, it is the object of the invention to provide a curtain coating unit which, with a low coating color flow rate, enables, with simple means, even better stabilization of the coating color curtain.

This object is solved by the features of claim 1. The slot also forms at least one adjacent to the web surface, or outside the width of the web falling curtain part, wherein the slot in the area outside the web surface or the web width is at least partially formed wider than the slot, the remaining or actual curtain on the Railway surface gives off.

As a result, the flow rate of the coating color curtain discharged from the wider slot adjacent to the web surface increases. As a result, the influence of the Coating surface tension decreases and prevents the curtain over the web surface from becoming disordered.

Thus, stable coating color curtains are obtained at low flow rates. The invention thus enables good coating performance at a reduced coating color flow rate.

It is envisaged that the slot is formed on the coating head so that at least one of its two edge-side ends is formed wider than the remaining part of the slot. This allows to reduce the width of the curtain coating.

An expedient embodiment of the inventive curtain coating unit is that the wider part of the slot has a width dimension, which is at least twice the width dimension of the remaining slot which is responsible for hitting the web is.

Therefore, the flow rate of the coating exceeds a certain necessary level, so that the force acting in the curtain discharge direction increases and an even more stable coating color curtain is obtained.

According to the invention, it is provided that the at least one wider slot has the shape of a rectangle, circle, oval or the like at the edge end.

It is very advantageous if the coating head is made up of two bodies, the widened slot being incorporated only in one body or in both bodies. The coating head is thus easier to produce.

The curtain coating machine can be further designed by the widened slot at a certain distance from at least one edge end of the coating head or its body is arranged. He therefore does not need to be located at the extreme end, but may also be positioned at other locations outside the web width.

Preferred embodiments of the invention:

In the following the invention will be explained by means of embodiments with reference to the drawings:

Show it:

• Fig. 1 (a) and (b) show the concept of operation of the curtain coating according to the invention according to embodiment 1, wherein Fig. 1 (b) in the direction of the arrow A in Fig. 1 (a) represents.
• 2 (a), (b) and (c) show cross sections along the lines CC and BB of the coating head in Fig. 1 (b) or the bottom of the in Fig. 1 shown curtain coating.
• 3 (a), (b), (c) and (d) illustrate the operation of the curtain coating unit according to embodiment 2 of the invention, wherein Fig. (b) shows the underside of the coating head in Fig. (a), Fig. (c) a cross section along the line DD in Fig. (a) and Fig. d show a cross section along the straight line EE in Fig. (a).
• 4 (a) and (b) show a first and a second variation of the curtain coating unit according to embodiment 2.
• Fig. 5 (a), (b) and (c) show the underside of the coating heads in the embodiments 1 and 2 with variations of the shape of the widened slots.
• Fig. 6 (a) and (b) show how a conventional curtain coating works and how it works Fig. 6 (a) shown curtain coating in a paint application with low flow rate (prior art).
• Fig. 7 shows the operation of a conventional curtain coating with guide plates (prior art).

Embodiment 1

The curtain coating 1 of this first embodiment is, as in FIG Fig. 1 (a) shown to a device which applies to the surface of a base paper web 2 a coating color t, wherein the web 2 is conveyed at a speed of 100 to 2000 m / min in the direction indicated by α arrow.

Fig. 1 (b) shows a view of in Fig. 1 (a) The curtain coater 1 dispenses a coating color t which is supplied via a coating ink supply inlet tk to the chamber of a coating head 3 discussed in more detail below, via a slot s1 and the wider slits s2 in the form of a curtain tc on the upper side of the conveyed web 2. In this case, coating curtain part (inner part) tc1 and tc2 are called edge-side curtain part. As a result, a coating color layer is formed in a predetermined thickness of, for example, 10 to 50 microns on the top of the web 2.

The particular feature of this curtain coating 1 is that the thickness m _c1 for the inner part of the coating color curtain tc1 above the top of the web 2 0.3 mm are specified, while the thickness m _{c2 of} the edge coating curtain parts tc2, which forms part of Show paint curtain next to the top of the web 2, 1 to 3 mm are given. As a result, higher flow rates are achieved in the coating color curtain parts tc2 at the two side edges than in the inner part of the coating color curtain tc1. As a result of the associated increase in weight, a resistance to the surface tension acting with orientation inwards on the marginal coating color curtain parts tc2 is built up and thus a stabilization of the coating color curtain tc is achieved.

This feature makes it possible for the curtain coater 1 to provide a given application performance with a given coating color amount t at a low flow rate.

As in Fig. 1 Thus, the coating color t delivered from the slits s1 and s2 provided on the coating head 3 forms the coating color curtains tc1 and tc2 and is then applied in a predetermined thickness to the upper side of the web 2. At the same time, as in Fig. 1 (b) shown in the color trough kp collected in addition to the top of the web 2 and therefore not applied to the web excess coating color t.

The collected coating color t is returned to a tank, not shown, and recycled together with newly supplied coating color t with a predetermined pressure by means of a pump. After defoaming, filtration and the like, it is then passed over the coating ink supply inlet tk of the chamber 3c (see. Fig. 2 (a) which has a cross section along the straight line BB in Fig. 1 (b) shows) of the coating head 3 supplied.

The coating color t conducted into the chamber 3c is discharged to the top of the web 2 for coating the top of the web 2 through the slots s1, s2 in the form of curtains tc1, tc2.

The brush shows how Fig. 1 (b) a body [3b], bilateral gaskets 3p sealing the body 3b and thus preventing leakage of the coating color t, and double-sided coating end plates 3e holding the gaskets 3p closely adjacent to the body 3b.

At this coating head 3 are how out of the bottom of the in Fig. 1 (b) showing pointing brush Fig. 2 (c) can be seen, a slot s1, provided. The slit s1 serves to form the inner coating color curtain tc1 and is provided on the coating head body 3b1, 3b2 with a width dimension m _s1 of 0.3 mm, the slits s2 are again provided with a width m _s21 of 1 to 3 mm at the seals 3p and serve to form the two marginal coating color curtain parts tc2.

Here, a width m _s1 = 0.3 mm for slit s1 and a width m _s21 of at least 0.6 mm for slit s2 is preferred. In particular values of 1 to 3 mm have proven to be ideal.

As a result of this different choice of the width dimensions m _s1 and m _s21 for slit s1 and slit s2, a higher flow rate is achieved in the edge-side coating color curtain parts tc2 than in the inner portion of the coating color curtain tc1.

In this embodiment, by way of example, 0.3 mm was selected as the width dimension m _s1 of slot s1, but it is possible to specify values of 0.2 to 0.5 mm as the width dimension m _s1 instead. Thus, the width dimensions m _s1 and m _s21 for slit s1 and slit s2, respectively, can be suitably selected according to the coating conditions, such as the thickness of the coating _color layer to be applied to the web 2.

The coating head body 3b has, as in Figs. 2 (a) and 2 (c) a first brush body 3b1 and a second brush body 3b2, which together form the body 3 and a coating head 3, respectively, and a first lip 311 and a second lip 312 received in the first and second brush bodies 3b1, 3b2, respectively, for adjustment serve the width of the slot s1.

The first and second spreader bodies 3b1, 3b2 are made of stainless steel, for example, as shown in FIG Fig. 1 (b) and Fig. 2 (c) 3, cutouts forming the chamber 3c of defined geometry and each side portion of the slit s1 having the predetermined width of 0.3 mm are formed in an elongated shape so as to be the width of the web 2 of 1 to 10 m or wider.

The lips 311, 312 are made of stainless steel, for example. In them a hole is drilled through which forms part of the 0.3 mm wide slot s1, as in Fig. 2 (a) shown by a (not shown) screw for adjusting and adjusting the width of the slot s1 is guided.

The seals 3p are in Fig. 2 (b) , a cross section along the straight line CC in Fig. 1 (b) , shown. These are, for example, components made of rubber or rubber, for example butadiene rubber. As in Fig. 2 (c) a slit s2 is formed in them, which is formed by a slit s21 having a width m _s21 of 1 to 3 mm around the slit s1 of the swab bodies 3b1 and 3b2 and a slit s22 along the slit s1 of the swab bodies 3b1 and 3b 3b2 is provided and has the same width dimension m _s22 = 0.3 mm. At the same time, a hole 3p1 corresponding to the chamber 3c in the coating head body 3b is formed in the gaskets.

Thus, since the width dimension m _{s21 of} the slit s21 in slit s2 is larger than the width dimension m _s1 (= 0.3 mm) of slit s1 in slit s2, a larger cross-sectional area is formed than in slit s1, therefore the coating color t passes through Slot s2 flows at a higher flow rate than through slot s1. Accordingly, the coating color curtain tc2, tc2 discharged from slit s2 is thicker than the coating color curtain tc1 discharged from slit s1.

In this example, as in Fig. 2 (b) however, the wider portion s21 of the slit s2 provided in the gasket 3p may be formed inwardly from the slit opening s2k over part of the entire length of the slit s2, but may be formed over the entire length of the slit s2 as it extends from the slit opening is shaped inside.

Thus, as in Fig. 1 (b) and Fig. 2 (c) Slots s2 forming part of the slits forming the coating color curtain next to the top of web 2 and forming edge portions tc2, tc2 of the coating color curtain have a wider width than slit s1, which overlies inner portion tc1 of the coating color curtain and thus over the upper side of the web 2 lying part of the coating color curtain forms. This causes an increase in the flow rate of the edge-side coating curtain curtain parts tc2 and, due to the accompanying increase in weight, reduces the influence of the inward surface tension on the edge coating curtain curtain parts tc2 and thus prevents the edge coating curtain curtain panels tc2 from being pulled inward.

This prevents the coating color curtain from becoming restless, thereby achieving stabilization of the coating color curtain and enabling a high-quality stabilized application or coating of the web.

Due to the increase of the flow rate in the edge coating color curtain parts tc2, since this increase leads to a stabilization of the curtain, a reduction of the total flow rate tc1 in the coating curtain is made possible.

For example, if a flow rate of 7.4 l / min / m was previously required to achieve a given coating performance, as has been verified by adjusting the slot s1, (which defines the inside coating color curtain tc1 above the top of the web 2) and the width of the web corresponds to 2), to a width m _s1 of 0.3 mm and adjusting the slits s2, which form the edge coating color curtain tc2 next to the top of the web 2 (ie outside the web width), to a width m _s21 of 3 mm, a reduction of the coating color flow rate to 5.4 l / min / m can be achieved.

By increasing the flow rate of the edge-side coating color curtains tc2, since the contraction of the coating color curtain inwards is correspondingly low, the coating color curtain is stabilized with the smallest width dimensions. Therefore, it is now possible to carry out the curtain coating with the smallest possible overall width.

The invention thus enables a curtain coating unit that provides a stable coating color curtain at high coating rates and works with low coating color flow rates.

Therefore, the application areas of curtain coating systems can be expanded and universal application areas for curtain coating systems can be developed.

Embodiment 2:

In the case of the curtain coating unit 21 of the embodiment 2 of the present invention, as shown in FIG 3 (a) and 3 (b) , An enlarged view of the underside of the coating head 23 in Fig. 3 (a) instead of forming slits in the seals 23p, 23p, instead a slit 2s1 and wider slits 2s2 are provided exclusively in the slug body 23b.

In this embodiment of the invention, an in-side coating color curtain 2tc1 is formed over the top of the web 22 by dispensing coating color t through the slit 2s1 provided in the coating head body 23b, and the high-rate edge coating paint curtains 2tc2, 2tc2 adjacent to the top surface of the web 22 become partially through Dispensing of coating color t formed by the slots 2s2, 2s2. This achieves a stabilization of the coating color curtains 2tc1 and 2tc2 and ensures the achievement of predetermined coating rates.

In this curtain coating 21, as in FIGS. 3 (a) and 3 (c) , a cross section along the straight line DD of the coating head 23 in FIG Fig. 3 (a) to form the inside paint curtain 2tc1, there is formed a chamber 23c for supplying the first coat body 23b1 and the second coat body 23b2 with coating paint t and a slit 2s1 adjoining the chamber 23c and having a width dimension m _s1 .

On the first and second coating head bodies 23b1, 23b2 are respectively provided a first and second lip 2311, 2312, at least one or both of which are adjustably held by a setting screw. At the first lip 2311 and the second lip 2312, the slit 2s1 is formed so as to be connected to the first swab body 23b1 and the second swab body 23b2.

As in Fig. 3 (a) is shown, as well as in Fig. 3 (d) , a cross section along the straight line EE of the coating head 23 in FIG Fig. 3 (a) to form the marginal coating color curtain portions 2tc2 formed adjacent to the top of the high-flow rate web 22 at the first and second coating head bodies 23b1, 23b2 adjacent to the chamber 23c and parallel to the slit 2s1, a slit 2s22 having a width dimension m _s22 identical to width dimension m _s1 is provided.

At the coating head bodies 23b1 and 23b2, a first and a second lip 2311 and 2312 are provided, which are held adjustable by means of adjusting screws. At these lips, the slit 2s22 is formed so as to be connected to the first swab body 23b1 and the second swab body 23b2. Below this, a slit 2s21 is provided which widens toward the first lip 2311 and has a width dimension m _s21 which is larger than the width of slit 2s22.

When the width dimension m _s1 of slit 2s1, over which the inside-side coating curtain part 2tc1 is formed, is 0.3 mm, as the width dimension m _s2 for the slits 2s2, over which the edge-side coating color curtain parts 2tc2 are formed, at least 0.6 mm must be selected, however, it is preferably selected in a range of 1 to 3 mm.

By the features of Embodiment 2, the same advantages as described in Embodiment 1 are obtained.

In the following, two variations of Embodiment 2 will be described with reference to FIG Fig. 4 explained.

In Embodiment 2, as in FIG Fig. 3 (b) shown in the extension of the slots 2s2, which form the edge-side coating curtain parts 2tc2, only an extension on the first Coating head body 23b1 made. However, in the case of the coating head 23 'of Variation 1, the slits 2s2' are instead provided so that, as in FIG Fig. 4 (a) , a drawing of the underside shown, their ends in each case by the same amount m3 in the first and second coat head body 23b1 ', 23b2' into expand.

In Variation 1, the slits 2s2 'are also arranged symmetrically to the plane in which the first swab body 23b1' adjoins the second swab body 23b2. However, the slots can also be arranged asymmetrically to each other.

When brush 23 "in Variation 2, as in Fig. 4 (b) , a representation of the underside of this variation, the slits 2s2 ", which form the thicker coating color curtain, each at a distance m ₄ to the ends of the first and second coating body 23b1", 23b2 "provided.

The wider slots 2s2 "must therefore not necessarily be formed at the two extreme ends of the coating color curtain, but can also be provided widened at other locations.

The widened slots can thus be positioned at the coating head so that their position is outside the top of the web 2 and destabilization of the curtain is avoided (cf. Fig. 1 (b) . Fig. 3 (a) ). The position of the widened slots is thus by no means limited to a particular position.

In the above embodiments 1 and 2, the widening of the slits was made on the two sides outside the upper side of the sheet, however, some effect is already obtained when the broadening is performed only on one side outside the upper side of the sheet.

The material in which the widened slots are provided can be chosen arbitrarily, for example, they can be provided widened slots on both the first and on the second coating head body, also they can, as in Example 1, in the coating head body seal or otherwise provided in that they connect both to the brush body and its seal.

As a cross section of the widened slots, a four-edged cross-section was shown in the embodiments 1 and 2, the in Fig. 3 (b) However, shown cross-section of slot 2s2 can also, as in Fig. 5 (a) shown, run around, and the in Fig. 4 (a) shown cross section of slot 2s2 ', as in Fig. 5 (b) shown, also run around. In the same way, the in Fig. 4 (b) shown slot 2s2 ", as in Fig. 5 (c) shown, run around.

The cross-section of the widened slots s2, 2s2, etc., may also take on a different shape, such as an ellipse or an oval or other shape, other than the four-edged or round shape shown in the embodiments, as long as it is ensured that the slot has a width in which the thickness of the curtain formed is at least twice the thickness of the curtain formed by the inner slit part s1, 2s1, etc.

Examples of application of the invention are brushes for painting cardboard and papers for calendars, catalogs, leaflets, thermal paper or pressure-sensitive paper, and brushes for one-sided coating of automatically debitable tickets with a magnetic coating color. As long as it concerns Streichwerke that apply a coating color on webs, the application possibilities of the invention are no limits.

reference numeral

1, 21, 100, 200 Curtain coater 2.22 train 3, 23, 23 ', 23 " String head s1, 2s1, 2s1 ', 2s1 ", s21, s22, 2s21, 2s22 slot s2, 2s2, 2s2 ', 2s2 " Slotted or widened slot tc Coating color curtain tc1, 2tc1 Upper edge of coated coating curtain tc2, 2tc2 in addition to the top of the train shaped coating curtain with larger curtain thickness t coating color 3b, 23b, 3b1, 23b1, 23b1 ', 23b1 ", 3b2, 23b2, 23b2', 23b2", 101, 201 String head body 3p, 23p, 23p, 23p " poetry 2311.311 String head lips 2312.312 String head lips 3e, 23e, 23e ', 23e " endplate m _c1 , m _c2 slot width m _s , m _s1 , m _s2 , m _s21 , m _s22 slot width m ₃ , m ₄ distance ce border area gb guide rod α arrow 3c, 23c chamber tk Coating color supply inlet 3p1 hole s2k slot opening

Claims (4)

1. Curtain coater (1) having a coating head (3) from which a coating colour (t) falls from above out of a slot (s1) provided on the coating head (3) onto a web (2), in particular of paper or board, running underneath it, and forms a coating colour curtain (tc), which reaches one side of the aforementioned web (2), the slot also forming at least one curtain part falling beside the web surface or outside the width of the web, the slot in the region outside the web surface or the web width being at least partly of wider shape than the slot which discharges the curtain onto the web surface, and the slot on the coating head being formed in such a way that at least one of its lateral ends (s2) is of wider shape than the remaining part (s1) of the slot,
   characterized in that
   the wider part of the slot (s2) has a width dimension which is at least twice the width dimension of the remaining slot or slots (s1).
2. Curtain coater according to Claim 1,
   characterized in that
   the wider slot (s2) has the shape of a rectangle, circle, oval or the like.
3. Curtain coater according to Claim 1 or 2,
   characterized in that
   the coating head (3) is built up from two elements (3b1, 3b2, 23b1, 23b2), the widened slot (s2) being incorporated in only one element or in both elements.
4. Curtain coater according to Claims 1 to 3,
   characterized in that
   the widened slot (s2) is arranged at a distance (m₄) from the lateral end of the coating head (3) or of the element or elements.

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