EP0003281B1 - Test installation for coating and drying of sheet material - Google Patents

Description

The invention relates to a test system for single or multiple coating and subsequent drying of paper or film webs with viscous liquids. Such a system consists of at least one pourer for the liquids and a downstream nozzle dryer with inertia-free adjustability of the state variables of the dry air.

When designing manufacturing plants, e.g. For coating foils or plates and for drying these goods, it is very important to know the coating and drying conditions before planning a system, in which optimal results for the quality of the product can be expected.

It is also of great value if a product developed on a laboratory scale can also be tested on a small scale for its behavior under later expected manufacturing conditions or can be adapted to these conditions. The exact knowledge of such characteristics is all the more important, the more the quality of a product or a substance of the manufacturing conditions, e.g. is influenced by the temperatures during drying, the humidity, the amount of air, etc. This is particularly the case with photographic products.

The German Auslegeschrift 1 962 089 describes a multiple sprinkler system that has a largely variable dry air flow. This system is intended for production. Because of its size, it would be uneconomical to use it for experimental purposes. There are limits to the size reduction because a certain minimum length is required for the dry sections. Therefore, the systems are still relatively large and expensive.

DE-AS 2 246 798 describes a test casting machine for single or multiple coating and drying of paper or film webs. In this system, the web is guided in a loop, and the individual founders are brought up to the side with their stations for casting under the casting roll, the supply and measuring lines required in modern coating processes being movable and having to be moved with. This is a considerable disadvantage, especially when using multiple founders.

Furthermore, the test facility according to DE-AS 2 246 798 does not allow the area in which the web is guided around the casting roll to be blown uniformly and without gaps with dry air. With this system it is therefore not possible to have a defined, uninterrupted drying process that would allow conclusions to be drawn about the transfer on a production scale.

Another disadvantage of this system is that constructive measures against harmful external influences (e.g. vibrations of the building), which can interfere with the coating process, can only be carried out with difficulty or with great effort. The entire machine can be set to vibration isolators, but this has the disadvantage that the system isolated from the floor contains many potential exciters (drive motors, metering, etc.).

A disadvantage of this system is, as it turns out in practice, that the web guidance over a drum with a relatively large heat capacity can have an undesirable influence on the result due to uncontrolled thermal effects from the rear, with targeted drying attempts.

In addition, with a web guide according to FIG. 1, DE-AS 2 246 798, the laying on of the web loop, particularly if it already contains sensitive layers and if the operation of the machine is carried out by a man for economic reasons, is relatively difficult without damage.

It is also disadvantageous that the web must be guided over a layer-side disc roller in order to ensure good winding around the casting roller. Experience shows that this is only possible up to a relatively narrow width, especially in the case of thin films, without deforming the film. If e.g. larger web widths are required for certain test purposes, this is not possible with such a disc roller deflection. The replacement of this roller, e.g. air-bearing or "vacuum rolls" would in turn require a considerably higher technical outlay and make the trial operation more difficult.

With this system, the rinsers have to be removed from the table for rinsing. The time required for this may be too long to be able to safely wash out all impurities within the caster (modern photographic substances, e.g. instant hardener solutions, sometimes have the property of reacting very quickly chemically).

The last disadvantage of the system has been found to be that a targeted, time-variable heat transfer from the rear, e.g. by air blowing, as is often desired, is not possible.

It is the object of the invention to create a simple, compact test installation which does not have the disadvantages listed above and thus makes it possible to apply both the coating and the drying conditions according to the requirements in production, I can simulate it completely and it excels in terms of design, operational safety, ease of use and the quality of the expected test results.

According to the invention the object was achieved in that the web formed as a flat loop, including its guide elements, is moved over one or more casters which can be brought into a fixed position and which are approached for coating in a chronologically defined sequence, and in that the web loop to be coated and the or the casters are coupled during the coating process and are mounted free of vibrations. Furthermore, according to the invention, after the coating, the caster or casters are lowered and in their place nozzle subchannels are folded in to blow the web loop.

According to a particularly expedient embodiment, the foundry is automatically rinsed after the coating, the web loop being moved out of the foundry area.

In a preferred embodiment, drying is carried out convectively or by radiation from the back of the web loop.

The web loop advantageously has no deflection elements on the layer side.

With the plant according to the present invention, it was possible to achieve that all parameters which have an influence on the properties of the product, i.e. which determine the good temperature-time curve and the drying speed, can be displayed with narrow tolerances. A simulation of large manufacturing plants is therefore possible with sufficient accuracy and meaningfulness. In addition, the plant according to the present invention can be used to determine design and process data, which are essential for the design of large plants and to avoid bad investments, in a very cost and time-saving manner (labor costs, energy costs, material costs).

The determination of such characteristic data is often only possible with such a simulation system, since large systems of the desired type are not available and the construction of such systems for trial purposes due to the high investment and trial costs. cost is not justifiable.

The optimization of processes with regard to the properties of the products through tests on existing large-scale plants would also not be possible because the resulting costs would be far too high. This is especially true then; when hundreds of process variants have to be run through to optimize a complicated modern product.

It is often doubted by experts that it is possible to determine characteristic values on a very small scale in process engineering processes, which are then also valid for large-scale production. Experience with plants according to the present invention, however, shows that the accuracy of the process control on these plants is sufficient to ensure transferable results with great certainty, both with regard to the physical parameters and with regard to the product properties.

• Figur 1 zeigt die Vorderansicht einer Versuchsanlage bei der die zu begießende Bahnschleife über mehrere Gießer gefahren werden kann.
• Figur 2 zeigt die Anordnung der Bahnführungselemente und eines Gießers von vorn.
• Figur 3 zeigt die Anlage von der Seite.

A preferred embodiment of the invention is described in more detail below with reference to drawings.

• Figure 1 shows the front view of a test facility in which the web loop to be cast can be run over several casters.
• Figure 2 shows the arrangement of the web guide elements and a caster from the front.
• Figure 3 shows the system from the side.

As can best be seen in FIGS. 2 and 3, the web 9 to be coated runs over 2 (or also several, e.g. diamond-shaped arranged) rollers 5, which in turn are fastened to a guide element 3. This rests on the console 7, which can be moved according to the arrow according to FIG. 2.

Similar to a rigid bed milling machine, in which one or more workpieces are clamped in a fixed position and in which the milling head is then moved over them, the foundry table 1 and the founders 15 thereon are fixed, and the web loop is moved over these foundries. The energy and measuring lines for the foundry are therefore permanently installed.

It is also easy to use, especially if you have to work in the dark, as the casters stay in the same place and are easy to find. Besides, is. the space requirement in this arrangement is less, since the long table, if it were mobile, would take up almost twice the length of its space.

Of course, the casters can also be arranged on a fixed rotary table.

Figures 2 and 3 show on the guide element 3 laterally movable gripping tongs 12, which are lowered, grasp the caster at the gripping heads 13 provided for this purpose and pull against stops next to the casting roller. The exact positioning is done by stops. In order to coat the web in a chronologically defined sequence, the web loop runs over the individual founders in a defined chronological order. Immediately after the watering, the caster is lowered again. As a result, the coated web loop is accessible all around and in the area where the caster stood during the coating, a nozzle channel piece 14 is closed. As a result, the ^/ web is now blown all around. Damping elements 6 are arranged between the movable bracket 7 and the guide element 3, which carries the rollers Sprue, ie if a caster 15 is lifted off the table 1 by the tongs 12, isolate the web loop and the caster from vibrations in relation to the machine and the room. In order to avoid a swinging of the 'transport supports' caused by acceleration processes in the lateral method, elastic buffers 16 are also attached laterally (see FIG. 2).

In order to be able to introduce heat into the web from the rear if necessary, the guide element 3 can be provided with holes on the web sides through which air of a defined consistency is blown onto the web. In addition or alternatively, it is also possible to attach radiators for rear heating.

Claims (5)

1. Experimental plant for the single or multiple coating of webs of paper or foil (9) with viscous liquids, followed by drying, comprising' at least one casting apparatus (15) for the liquids and followed by a nozzle drier with inertia-free adjustability of the parameters of the drying air, characterised in that the flat loop of web (9) including its guide elements (3) is displaced over one or more casting apparatus (15) which are able to be placed in a fixed position and are successively moved into the operative position for coating in a predetermined time sequence and in that the loop of web (9) which is to be coated and the single or multiple casting apparatus (15) are coupled during the coating process and are mounted to be free from vibrations.

2. Experimental plant according to Claim 1, characterised in that after the coating step the single or multiple casting apparatus (15) is/are lowered and nozzle channel portions (14) are clamped in the place of the casting apparatus for the loop of web (9) to be blasted with air.

3. Experimental plant according to Claim 1 or 2, characterised in that automatic rinsing of the casting apparatus sets in after casting, the loop of the web (9) being removed from the range of the casting apparatus (15).

4. Experimental plant according to one of Claims 1 to 3, characterised in that the loop of web (9) is dried from the reverse side by convection or radiation.

5. Experimental plant according to Claims 1 to 4, characterised in that the loop of web (9) does not contain any deflecting elements facing the side of the web which is coated or to be coated.

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