JPH0371185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for guiding at least one coating solution flowing down a sliding surface and, in the case of a curtain-type coating device, for guiding at least one coating solution flowing down a sliding surface. For hopper type coating equipment, bead (coating)
The present invention relates to a coating device having edgings provided on the sliding surface in order to stabilize the coating solution flowing down the sliding surface.

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION It is particularly economical when the coating operation of photographic materials consisting of a number of different layers is carried out in one working step, rather than layer by layer. , has been known for some time.

"Curtain type or slide hopper type coating method"
The method known under the name . is carried out using an apparatus consisting of a triangular prismatic block made of several plates in which there are a number of longitudinal distribution channels corresponding to the number of layers to be applied; Each coating solution is weighed and delivered separately. A slit is located above each distribution conduit, into which the coating solution is directed through the distribution conduit under pressure. All slits open at the top of the smoothly sloped sliding surface so that the coating solution flows down in a continuous and evenly distributed layer.

The planes assigned to each layer can be located in the same plane in this arrangement, or they can be offset from each other little by little in the form of small plateaus, approximately corresponding to the thickness of the layer in each slit area. . As a result, the coating solution where the outlet slit is located downstream of the sliding surface is coated in a layered manner by the coating solution discharged upstream, and finally at the end of the sliding surface. A liquid film consisting of several distinct layers is produced.

This liquid film is transferred and applied to the moving web surface by either a free surface tension surface (meniscus) or a free falling curtain. When using a free surface tension surface, i.e. when using a sliding hopper type coating device, the web surface to be coated moves at a narrow distance from the end surface of the sliding surface. When using a free-falling curtain, i.e. when using curtain-type coating equipment, there is a gap between the end face of the sliding surface and the web surface that is sufficiently wide to form a free-falling curtain. Coating is performed.
These devices allow multilayer coating solutions, on the order of three, four, or even twelve layers, to be simultaneously and easily transferred onto the web surface to be coated. Experience has shown that if the process is carried out properly, each layer flows as it flows down an inclined sliding surface, or in a free surface tension surface or free-falling curtain, or on a moving web surface in a subsequent drying step. It has been shown that they do not mix with each other.

However, those skilled in the art are aware of the fact that slide hopper or curtain type coating equipment has several serious drawbacks, which become more pronounced the higher the number of layers applied in a single process. you will notice.

While the coating solution flows down on the sliding surface, an uncertain flow condition occurs at the edge of the sliding surface, which induces turbulence in the flow of the coating solution on the slide hopper type coating device, It destabilizes the bead, especially at the edge of the sliding surface.

To overcome this drawback, it is necessary to provide edges on both sides of the sliding surface in order to stabilize the flow of the coating solution at the edges of the sliding surface and further stabilize the bead.

The coating solution is slid by a simple metal protrusion flush with the outer surface of the coating solution discharge slit and mounted on the sliding surface to guide the edges of the coating solution. It can be guided at the edge of the surface.

A border of this type is known from GB 2038211. The edging device described in this British patent causes the coating solution to rise above the vertical boundaries of the lug guide due to its surface tension, resulting in an increase in the thickness of the coating solution at the edge. It has the following drawback.

This thickness increase in coating solution is transferred onto the coated web surface. These thicker sections require significantly longer drying times and result in material loss as these thicker sections must be cut from the web as unusable edge bands.

In curtain coating equipment, a local increase in layer pressure at the edging tool results in thinning of the layer in adjacent areas, which can induce tearing of the curtain during the curtain coating process.

To overcome these drawbacks, the sliding surface is widened at its lower end by an angle of up to 10°, so that
A edging device is described in GB 2038211 in which the layer is thinner at the edge.

To stabilize the bead in slide hopper type coating equipment, reduced pressure must be applied to the edges, which itself tends to produce streaky coatings.

A method and a device for applying a self-adjustable low pressure to the edge in order to eliminate an increase in the thickness of the edge are known from GB 2029733. This method reduces the risk of separation of the coating solution at the edges.

The improvements described above regarding the edge guidance of the coating solution are not achieved for the flow at and from the slide surfaces in slide hopper type coating devices. Additionally, the method described above cannot be used for curtain coating equipment since low pressure cannot be applied to the curtain of free-falling solution. The device for applying different low pressures to the central region and to the two edge ends is technically very complex.

A method and a device for reducing edge bulge are known from European Patent Application No. 80200297. In this method, the coating solution discharge slit has a width that differs depending on the location of the sliding surface.

In other words, the coating solution discharge slit at the lowest end on the sliding surface is the narrowest, and the next upper slit is the narrowest.
It is getting wider by mm. This method has the disadvantage that when the number of layers is high, the unusable edge area is large and considerable losses occur due to this unusable edge band.

Therefore, the present invention aims to optimally guide the coating solution over the sliding surface, to properly stabilize the bead in a slide hopper type coating device, and to properly stabilize the bead on the end surface of the sliding surface in a curtain type coating device. It is an object of the present invention to provide a edging device of the kind described above, which facilitates stabilizing the flow of the coating solution at the edges of the web and at the same time suppressing the increase in thickness at the edges of the web.

Means for solving the problem This object is achieved by the invention using a border of the design described above. This edging tool includes (a) a vertical surface 6 having a height g from the sliding surface 2 of 0.1 to 0.5 mm and extending parallel to the flow direction of the coating solution; and (b) the vertical surface 6. (c) an outwardly inclined inclined surface 9 connected to the sliding surface 2 and having an angle α of 5 to 40 degrees; has a base 17 parallel to surface 2,
And the height h of the base 17 from the sliding surface 2 is
A chamfered surface 8 provided at the end of the sloped surface 9 on the terminal surface 3 side having a thickness of 0.1 to 0.5 mm, a ridge 18 where the chamfered surface 8 and the sloped surface 9 intersect, and a base 19 of the sloped surface 9 The angle β formed with
~40°.

Surprisingly, this edging of simple construction creates very good flow conditions on the sliding surface, both for single layer as well as for multiple layers. Remarkably, it is surprising to those skilled in the art that in curtain coating equipment, tearing of the coating solution does not occur earlier at the edges than at the center. Furthermore, the important requirement of a small bulge at the edges on the web is also met.

The essential advantage of the edging device according to the invention is therefore its simple form, which can be produced at low cost, and its long service life, which makes it suitable for use on the end faces of sliding surfaces in curtain-type coating machines or in slide hopper-type coatings. It is based on reliable guidance of the coating solution in the bead in the device.

Another fact surprising to the person skilled in the art is that when the number of layers becomes large (6 layers and more), this causes the total layer thickness on the sliding surface to be reduced by the amount weighed at each coating solution outlet slit. and viscosity, without the need for corresponding modification of the edging device or replacement of the edging device, even if the edging device becomes thicker in response to the viscosity.

If the number of layers increases and the layer on the sliding surface becomes correspondingly thicker, the coating solution lies in a smooth layer on the inclined surface adjoining the vertical surface of the edging. It is not necessary to shift or step-change the coating solution delivery slit in the edging tool.
The edging tools do not need to be replaced due to changes in various manufacturing conditions, including changes in the amount of layer coating solution, layer viscosity, and number of layers, and one particular pair of edging tools can be used over a wide range of applications. It is particularly important that it can be used over a wide range of applications.

Surprisingly, there is considerable convenience and time savings for the operator in the wetting operation of the sliding surfaces and edges using small rods or plates, which is necessary before starting up the coating equipment. brought about. Overwetting of the sloped surface, ie higher wetness than is established in the steady state on the sloped surface, is unexpectedly required. This is because, due to surface tension, a smooth transition between the fixed slope and the coating solution is automatically and cleanly regulated.
Therefore, the operator can safely moisten all of the edging devices, and in particular all of the coating solution delivery slots, at any time by rapid, continuous movements with the dampening wand. Although all of the coating solution in this edge wetting and multilayer process is lost, much coating solution can be saved due to the time savings. Therefore, single-layer and multi-layer coatings can be advantageously carried out using multi-layer slide hopper type coating equipment or multi-layer curtain type coating equipment without changing the edging tool.

Furthermore, it is very advantageous that the edge bulge or the increase in edge thickness in the wet state is surprisingly small, so that it can be dried faster in the drying device and thus the operating speed can be increased. It is. With this streamlined and economically more favorable operation, considerable technological advances have been achieved.

An advantageous embodiment is characterized in that said angle α and angle β are preferably from 10 to 30°, more preferably from 30°, and said height g and height h are preferably from 0.2 to 0.4 mm. .

Depending on the number of layers and the viscosity of the coating solution, special shaping of the edging is required.

Surprisingly, in one embodiment, the edging device can be used within a wide range in terms of number of layers and viscosity. Depending on the objectives set for these areas, two or three edging implementations may be sufficient to carry out all coating operations.

That is, angle α = 30°, angle β = 30°, height g = 0.4
The edging with mm and height h = 2 mm is 70 m/
It is distinguished by the fact that it can be used successfully for a viscosity range of 5 to 150 mPa·s (milliPascal·s) and for 1 to 7 layers at a coating speed of 100 min.

For lower viscosities and fewer layers, the angle α
A edging with = 10°, angle β = 10°, height g = h = 0.2 mm is advantageous.

Borders of this kind are suitable for viscosities of 1 to 5 mPa·s and for one or two layers.

In an advantageous embodiment, the edging on the sliding surface has an angle γ=
Positioned at 90°. This prevents changes in the thickness of the coating solution flowing down between the coating solution discharge slit and the end surface of the sliding surface.

The edging device can be positioned on the sliding surface such that the vertical side of the edging device facing the coating solution forms, together with the outer surface of the coating solution discharge slit, a plane with respect to the coating solution. A regular layer thickness of the coating solution is thus produced over the entire width of the sliding surface.

In a particularly suitable embodiment, the vertical surface of the edging device may be arranged outwardly from the outer surface of the coating solution delivery slit by a narrow distance S.

Depending on the spacing S from 0.1 to 3 mm, the layer pressure at the edge is thinned, so that the bulge of the edge on the web is reduced or can be controlled by adjusting the arrangement of the edging.

Specific examples of the present invention will be described with reference to the accompanying drawings.

FIG. 1 illustrates a cross-sectional view of the central portion of a multilayer slide hopper coating device, FIG. 2 is a perspective view of the lower portion of the edging on the sliding surface, and FIG. 3 illustrates the coating device. Figure 2 illustrates a cross-sectional view of the central portion and flowing down five layer coating along the transverse line A--A of Figure 1;

FIG. 1 schematically illustrates the central portion of a multilayer slide hopper type coating device of basic design.

The coating solution is pushed upward by the pump through the coating solution discharge slit 4 and reaches the sliding surface 2. Due to the slope of the sliding surface 2, the coating solution flows down the sliding surface 2 under the action of gravity and is deposited in a thin layer. A bead is formed on the end surface 3 of the sliding surface at the end of the sliding surface 2, between the end surface 3 of the sliding surface and the web 10 guided on the coating roller 11. The layers from the different coating solution delivery slits 4 are applied from a bead onto the web 10 without being mixed.

Although not shown, a multilayer curtain type coating device operates in the same manner. The layer or layers flow one above the other on a sliding surface 2, which in the case of curtain coating equipment is usually designed like a nozzle.
is applied in the form of a curtain that falls freely onto the web 10, which moves in a generally horizontal direction.

For lateral guidance of the coating solution flowing over the sliding surface 2, identical symmetrical edging devices 1 are arranged on both sides of the sliding surface 2. Only one edging is shown in the cross-sectional view of FIG. The edging 1 has a vertical surface 6 which is perpendicular to the sliding surface 2 and extends at the same height g over the entire length of the sliding surface 2.
This vertical surface 6 is in the same plane as the end surface 3 of the sliding surface 2 at the lower end of the sliding surface 2 . The height g of the vertical surface 6 is in the range of 0.1 to 0.5 mm. A height g of the vertical surface 6 of 0.2 to 0.4 mm is sufficient for many coating processes.

A sloped surface 9 that slopes outward at an angle α with the sliding surface 2
is connected to the vertical plane 6. The inclined surface 9 extends relative to the fixed body of the edging 1 and over the entire length of the sliding surface 2. The angle α between the inclined surface 9 and the sliding surface 2 is 5 to 40 degrees.

The sloped surface 9 of the edger 1 is cut diagonally at the end of the sliding surface 2, and this part forms a chamfered surface 8. The chamfered surface 8 has a base 17 extending from the same plane as the end surface 3 of the sliding surface 2. The height h of the bottom side 17 from the sliding surface 2 is 0.1 to 0.5 mm. A ridge 18 where the chamfered surface 8 and the inclined surface 9 intersect, and the inclined surface 9
The angle β formed with the base 19 is 5 to 40 degrees.

The dimensions of the vertical plane 6 and the angles α and β with respect to the heights g and h depend, as mentioned above, on the number of layers, the thickness of the layers and the viscosity of the coating solution. several layers and/or
or in the case of low viscosity and/or thin layer thickness, small values for the heights g, h and small values for the angles α, β are selected for the end surface 5 below the vertical plane 6 and the chamfered surface 8. . In the case of a large number of layers, for example 3 to 12 layers and/or high viscosity and/or thick layer thickness, the heights g, h relative to the end surface 5 below the vertical surface 6 and the chamfered surface 8 are Large values are selected for angles α and β. The edging device 1 with specific dimensions can be used in a wide range of production conditions without flow at the end, deterioration of the flow properties at the bead in slide hopper type coating equipment or disturbance of the generated curtain in curtain type coating equipment. As mentioned above, it can advantageously be used for

FIG. 2 is a perspective view of the lower part of the sliding surface 2 including the edging 1. FIG. The edging tool 1 is formed with an inclined surface 9 which is inclined at an angle α with respect to the sliding surface 2 and allows the coating solution coming out of the coating solution discharge slit 4 to slide. This inclined surface 9 is the sliding surface 2
terminating in a vertical surface 6 extending from the top with a height g.

At the end of the sliding surface 2, the inclined surface 9 ends in a chamfered surface 8. This chamfer 8 leads to the end surface 5 below a vertical chamfer 8 of height h which is in the same plane as the end surface 3 of the sliding surface 2 . The height g of the vertical surface 6 and the height h of the end surface 5 below the chamfered surface 8 may be the same. The width bt of the inclined surface 9, that is, the maximum width of the chamfered surface 8, that is, the length of the base 17, is 20 to 30 mm depending on the inclination angle α.

A vertical surface 6 of the edging 1 extending perpendicularly from the sliding surface 2 limits the sliding surface 2 on both sides. The vertical surface 6 of the edging device 1 is positioned on the sliding surface 2 in such a way that it extends at a right angle γ to the coating solution discharge slit 4 and is coplanar with the outer surface 7 of the coating solution discharge slit 4. You may.

In order to achieve the desired thinness of the edge of the layer along the edging tool 1, the edging tool 1 must be spaced a narrow distance 〓S from the outer surface 7 of the coating solution discharge slit 4, as shown in FIG. It is preferable to arrange the vertical plane 6. Depending on the surface tension of the coating solution, the distance S is 0.1 to 3 mm.
or can be adjusted accordingly.

The edging elements 1 lying symmetrically opposite the center line M of the sliding surface 2 are mirror images of each other, so that only one of the edging elements 1 is shown in the figure.

FIG. 3 illustrates a cross section of the coating device along line A-A in FIG. Edging tool 1 at the edge of the sliding surface
A section is shown highly enlarged, with a vertical surface 6 extending perpendicularly from the sliding surface 2 at a height g and an inclined surface 9.
is inclined outwardly at an angle α with respect to the sliding surface 2.

On the sliding surface 2, a coating of five layers 12 to 16 is shown. The layer is uniformly supported on the inclined surface 9 and when it reaches the end surface 3 of the sliding surface 2, the sliding surface 2
The edges of the coating are thinned so that no bulges are formed at the lower ends of the coating and the five coated web is coated with substantially no bulges at the edges.

The height g of the vertical surface 6 is 0.5 mm and corresponds to the thickness of the bottom layer 12, depending on the amount of coating solution weighed and the viscosity. The height g of the vertical surface 6 and the height h of the end surface 5 below the chamfer 8 as well as the angles α and β are, as already mentioned above, relative to the intrinsic viscosity of the coating solution and the weighed amount, e.g. It is clear that the values used in the coating of the magnetic tape and in the hydrous monolayer structure will take on different values.

Example 1 In a multilayer slide hopper type coating device, the following dimensions: Height of vertical surface 6 g 0.4 mm Height of end surface 5 below chamfered surface 8 h 2.0 mm Angle α 30° Angle β 30° The edging tool 1 has a slip resistance in a viscosity range of 5 to 150 mPa·s and a web speed of 70 m/min and in the application of 1 to 7 layers on the web, each layer having a wet thickness of 20 μm. A very good guidance at the edges of the surface 2, a stable bead formation in the center and at the edges of the end surface 3 of the sliding surface 2, and almost no edge bulges on the web are achieved. The length of the drying device could be shortened by 20% because it could be dried in the same amount of time as the center of the web.

Example 2 In a multilayer slide hopper type coating device, the following dimensions: Height of vertical surface 6 g 0.2 mm Height of end surface 5 below chamfered surface 8 h 0.2 mm Angle α 10° Angle β 10° The edging tool 1 has a edging tool 1 that can be used at the edge of the sliding surface 2 when coating one or two layers with a wet layer thickness of 42 μm at a low viscosity range of 1 to 5 mPa·s and a web speed of 70 m/min. of the web, which achieves a very good guidance in the area, the formation of a stable bead at the edges as well as the central part of the end face 3 of the sliding surface 2, and which can dry in substantially the same time as the coating in the central part of the web. The edges have been created.

Example 3 In a multilayer curtain coating device, a edging having the following dimensions: Height of vertical surface 6 g 0.4 mm Height of end surface 5 below chamfer 8 h 0.4 mm Angle α 30° Angle β 30° 1 was adapted to the sliding surface 2 in such a way that it extends to the end of the sliding surface 2. The curtains consisting of a quantity were stretched out on guide rods after leaving the sliding surface 2 in a customary manner to avoid shrinkage below the edging 1.

Very good guidance at the edge surface on the sliding surface 2 when applying 3 to 6 layers at a viscosity range of 10 to 80 mPa·s, a thickness of each layer in the wet state of 20 μm and a web speed of 120 m/min. was achieved. The layer of coating solution at the edge of the edging device 1 is clearly separated from the edge surface of the sliding surface 2 to the free fall onto the web moving beneath it, and the bulge at the edge is similar to that of the entire web. It was only slightly thicker compared to the thickness, so the edge bulges dried in substantially the same amount of time as the center of the web.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of the central part of the multilayer slide hopper type coating device, FIG. 2 shows a perspective view of the lower part of the edging on the sliding surface, and FIG.
FIG. 2 illustrates a cross-sectional view of the central portion and the five layers of coating material flowing down along the line A--A of FIG. 1 across the coating device. In the figure, 1... edging tool, 2... sliding surface, 3...
Terminal surface of sliding surface, 4... Coating solution discharge slit,
5... End surface below the chamfered surface, 6... Vertical surface, 7
... Outer surface of coating solution discharge slit, 8 ... Chamfered surface, 9 ... Inclined surface, 10 ... Web, 12
~16...Coated object, 17...Base of chamfered surface, 1
8... Edge where chamfered surface and inclined surface intersect, 19...
...This is the bottom of the slope.

Claims (1)

[Claims] 1. A slide hopper type or curtain type slide hopper type comprising: a sliding surface 2 having a terminal end surface 3; and a coating solution discharge slit 4 opening in the sliding surface 2 and having an outer surface 7. It guides at least one coating solution flowing down the sliding surface 2 used in the coating device, and in the case of a curtain-type coating device, at the terminal surface 3 of the sliding surface 2, it is applied to the slide hopper-type coating device. In order to stabilize the coating solution in the bead, the coating device has a edging tool 1 provided on the sliding surface 2, and the edging tool 1 is (a) upright on the sliding surface 2. and a vertical surface 6 having a height g from the sliding surface 2 of 0.1 to 0.5 mm and extending parallel to the flow direction of the coating solution, (b) connected to the vertical surface 6, and (c) an outwardly inclined inclined surface 9 having an angle α with the sliding surface 2 of 5 to 40 degrees; (c) a base parallel to the sliding surface 2 on an extension of the same plane as the terminal surface 3 of the sliding surface 2; has 17;
And the height h of the base 17 from the sliding surface 2 is
A chamfered surface 8 provided at the end of the sloped surface 9 on the terminal surface 3 side having a thickness of 0.1 to 0.5 mm, a ridge 18 where the chamfered surface 8 and the sloped surface 9 intersect, and a base 19 of the sloped surface 9 The angle β formed with
A coating device characterized in that the angle is ~40°. 2. The coating device according to claim 1, wherein the angle α and the angle β are 10 to 30 degrees, and the height g and height h are 0.2 to 0.4 mm. 3. The coating apparatus according to claim 1, wherein the outer surface 7 of the coating solution discharge slit 4 and the vertical surface 6 are in the same plane. 4. The coating device according to claim 1, wherein the vertical surface 6 is disposed outwardly from the outer surface 7 of the coating solution discharge slit 4 by a distance of 0.1 to 3 mm.