DE2155386A1 - Coating and drying device for web-shaped materials - Google Patents

Description

PATENTANWÄLTE DIPL.-ING. WERNER FREISCHEM

ILSE FRElSCHEM

5000 COLOGNE HEUMARKT 50 TE LE FON: (02 21) 23 5 · ··

Multitec AG Bern (Switzerland)

Coating and drying device for web-shaped

materials

The present invention relates to a coating and drying device for web-shaped materials, in particular for paper and film webs, with applicators and drying rooms arranged between them, in which the web-shaped material is guided over support rollers.

Combined coating and drying devices for web-shaped materials have been known for a long time. For drying, hot air nozzle dryers are primarily used, if necessary in combination with IR radiation dryers. In particular in the paper and film processing industry, especially for the production of light-sensitive reproduction materials, several coatings are usually applied to both sides of the material web. Of course, each coating must be dried before applying another layer. Any contact with the freshly applied layer must be avoided during the drying process. In the known devices, the coated

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te material web with the freshly coated side up in a wide state through a drying channel by being passed with the dry underside over support rollers, which can be freely rotating or driven. When moistened, paper webs in particular tend to warp and curl from the edges, which can result in undesirable longitudinal folds. This tendency occurs all the more the smaller the contact surface of the material web on the circumferential surface of each support roller and the greater the distances between the individual support rollers. The contact surface of the material web on the circumferential surface of the support roller could be increased accordingly by guiding the material web around a support roller with a large diameter at as acute an angle as possible. However, this inevitably leads to large distances between individual support rollers. In the known drying devices, this disadvantage has been remedied in that the drying channel was designed in the form of a flat arc and supporting rollers of small diameter were attached in this close to one another. In order to enable a continuous coating with several layers and the corresponding intermediate drying, two or more such curved drying channels were arranged one above the other and an applicator for the coating with a corresponding deflecting roller system was attached to both sides of this arrangement. The return of the material web coated and dried on one side via the second applicator and through the second drying channel located above the first usually means that the second coating is applied to the other side of the material web. Theoretically, it is easily possible to deflect the material web in such a way that the second coating can be applied to the first, dried layer and, furthermore, it would theoretically be possible to arrange several applicators with corresponding deflection roller systems _{on one or both sides of the 3 curved drying channels lying one above the other.} However, since the lanes cannot cross and, in addition, until a freshly

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The coating carried on the coated side must not be touched, the result is such a complicated and extensive path that such devices are not used in practice. Devices with curved drying channels, which are used in practice, usually consist of two drying channels lying one above the other and an applicator at each of the inlet and outlet ends of these channels.

Another known device comprises a plurality of consecutive in-plane units, each of which consists of an applicator unit and an associated flat {drying channel. By appropriately deflecting the coated and dried material web, it is possible to program further coatings in subsequent units as desired, ie to apply several coatings one after the other on the same side or alternately on both sides and to dry them. Above all, this system has the disadvantage that, due to the arrangement in one plane, it requires an extremely large base area. Another disadvantage, which has already been pointed out above, is that due to the straight web guide through the flat drying channels, only the minimal contact surface of the material web can be achieved on the circumferential surface of the support rollers and thus the possibility of distortion and longitudinal creases in the material web increases.

Both of the known drying devices described above show the same considerable disadvantage when they are expanded as hot air nozzle dryers. When drying irt by means of hot air blown in through nozzles must on the one hand be aimed for to bring this hot air into contact with the material web as evenly as possible throughout the channel and on the other hand, the resulting moist exhaust air is as uniform as possible.

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to deduct massively. This is usually done via a closed Circulation system, where part of the humid exhaust air is expelled into the atmosphere and replaced by fresh air and the mixture heated in a water heater? and fed back to the nozzles will. It is now a well-known fact that from a flow engineering point of view it is extremely difficult in flat or curved channels of rectangular cross-section to create absolutely uniform flow conditions, so that there are no dead spots or congestion spots.

It is known to every person skilled in the art that wet-coated paper webs move from the edges against the coated side roll up and that this phenomenon turns into the opposite during drying, so that the edges are against the uncoated Set up on the web side. However, since the support rollers are located under the uncoated side of the web, the There is a great risk that the erected or rolled-up parts of the paper web between the rest of the paper web and the support rollers be clamped and folded in place. This occurs in particular in facilities with flat drying channels, since here the already mentioned minimal contact surfaces between the material web and the circumferential surface of the support rollers with dead flow angles or The hot and exhaust air congestion points interact. Various means have already been used to remedy this evil, for example special nozzle shapes and cooperating storage boxes proposed, however, all of which are complicated, expensive and not universally applicable.

It is an object of the present invention to provide an apparatus which can be as described above Does not have disadvantages and it allows material webs continuously and in any order with less space requirement to coat several times and the corresponding intermediate drying in a rational way and without the risk of distortion and

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Perform longitudinal creasing.

According to the invention this is achieved in that the geometric axes of the support rollers in a cylindrical surface lie.

In the device according to the invention, any known applicators are used, which preferably consist of an applicator roller and an air brush with a corresponding counter roller exist.

The arrangement of the support rollers in a cylinder jacket surface offers the advantage, on the one hand, that the circular Guiding the material web over the support rollers the largest possible contact area between the material web and the circumferential surface of the support rollers is guaranteed, whereby the risk of distortion and longitudinal wrinkling is eliminated, and that on the other hand, the overall length and thus the space required for a unit consisting of one or two applicators and a drying device to approximately a third of a known device of the same capacity is reduced.

The housing of the drying device according to the invention is opposite to the known flat or curved drying channels round and the coated web of material is inside this housing on a circular path over the support rollers so that the coated and dried Material web exits through the same housing slot as it was introduced. The slot nozzles for introducing the hot air are distributed over the circumference of the housing on its inside and are with the blowing direction of the hot air against the Axis of the cylindrical housing directed towards the coated side of the continuous web of material. This arrangement fixes

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all deficiencies in relation to blind spots and stagnation zones in the flow flow, as described above with respect to drying channels is. The hot air is thus supplied evenly distributed over the entire circumference of the cylindrical dryer housing and flows evenly towards the axis of the housing. An axially opens into one end face of the cylindrical dryer housing Extraction line for the moist exhaust air and extends axially a little way into the housing. On the opposite At the front of the dryer housing there is an intake opening for fresh air that can be regulated with a lamella closure. The exhaust duct is connected to the suction port of a blower fan, which draws in the exhaust air, via an intermediate piece into a Flow heater in the manner of a heat exchanger and blows from there back into the distribution channels to the exhaust nozzles. in the The intermediate piece between the fan and the flow heater is an outlet line connected to the atmosphere, the opening of which can be regulated by means of a flap. Part of the humid exhaust air is released through this line ejected, creating a vacuum in the air circuit. This vacuum can be achieved by regulating the shutter of the Fresh air intake opening in the front of the cylindrical dryer housing must be balanced so that at the inlet and outlet slot the material web in the dryer housing no air flow, neither from the outside to the inside nor from the inside to the outside occurs. Such a streamlined mode of action can be achieved with flat or arched duct dryers practically not achieved even when using the most complicated inlet and outlet chicanes will.

Any number of the units described above can be strung together, depending on the desired number of coatings will. As a rule, three are sufficient for most of the types of coating used in practice today such units, which are eight different variants in terms of

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Allow number and order of coating. Of course the number of units can be increased as required or reduced for special cases.

Another advantage of the device according to the invention is that each individual unit has a separate Air circuit and associated water heater can be provided, so that an individual treatment temperature in each dryer unit can be set and maintained automatically by thermostatic regulation of the supply and exhaust air temperature.

In the following, a preferred embodiment of an inventive device i as well as the programming possibilities of this device durch.Variation of the continuous path is the. Material web explained with reference to the drawings, for example.

In the drawings show:

1 shows a schematic representation, partly in section, of an embodiment of a drying device according to the invention using hot air as the drying medium from which the air circuit emerges;

FIG. 2 shows a schematic representation of a cross section along the line A-A of the cylinder dryer according to FIG. 1;

FIGS. 3 - 10 show a preferred one in a schematic representation Embodiment of a coating and drying device according to the invention using three drying units according to FIG. 1 with the associated contract works, from which the different intake or passage of the material web Eight different types of coating can be seen without moving mobile parts of the device.

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In the drawings, identical parts are provided with the same index numbers.

In Pig. 2, the wet material web 2 coated on the side indicated by arrow 1 runs through in the direction of the arrow the inlet and outlet slot in the cylindrical housing of the drying device, it passes through on a circular arc Web in physical contact of the uncoated material web side with the support rollers arranged in a cylinder jacket surface 3 and leaves it after deflection via the deflection roller 20 through the same slot through which the introduction takes place.e. On the inner wall of the cylindrical housing 4 are opposite the support rollers Slot nozzles running over the entire width of the housing

5 attached, through which hot air blown from the inlet manifold 6 into the cavity 7 connecting the nozzles onto the coated Side of the material web is blown. This hot air, which evenly over the circumference of the cylindrical inner wall distributed, is blown radially into the cylindrical housing 4 ', acts on and flows around the continuous web of material due to of the suction end of the exhaust air line 8 penetrating a little into the cylindrical housing evenly, as shown in FIG. 1 is indicated. Due to the circular guidance of the material web The contact surface between the material web is controlled by the support rollers and support roller circumferential surface compared to a straight course in a flat drying channel is significantly enlarged and this eliminates the risk of distortion, longitudinal creasing and folding of the material web edges.

From the schematic representation according to FIG. 1 is now the further circulation of the air can be seen, with the humid exhaust air via the exhaust air line 8 into the intake port 9 of the blower fan 10 sucked in and from this via the intermediate piece 11, the flow heater 12, hot air line 13 and inlet manifold

6 blown again into the cavity 7 connecting the slot nozzles 5 will.

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However, the absorbed moisture must now be at least partially removed from this closed circuit. For this purpose, a drain pipe 14 is on the intermediate piece 11, which is in communication with the atmosphere and the passage of which can be regulated via the flap 15. Opposite to the intake end of the exhaust air line 8, which is axially inserted through an end face of the cylindrical dryer housing, is located in the The other end wall of the dryer housing has a suction opening 16, the passage of which can be regulated via a lamella closure. at Opening the flap 15 creates a negative pressure in the air circuit, so that at the inlet and outlet slot of the cylindrical dryer housing 4 Cold air is sucked in and thus the aerodynamic flow of the drying air and so- " would interfere with the drying process. By appropriately opening the lamella closure of the suction opening 16, the pressure conditions however, they can be balanced effortlessly and in a simple manner in such a way that no air movement whatsoever at the inlet and outlet slots occurs more. This arrangement also leads to the remarkable The advantage of replacing the over flap 15 and drain pipe 14 emitted, moist air required fresh air without complicated blower and pressure regulating devices, is replaced by fresh air, which is also without any disturbance of the aerodynamic air flow and without contact with the material web running through with the one from the exhaust air line | sucked drying air mixed.

The circulating air drying system for aqueous coatings described above can be used effortlessly and within a very short time a through-air drying system for solvent-based coatings or paintwork can be changed. For this purpose, the intake port 9 of the blower fan 10 is against the exhaust air line 8 completed and connected to the free atmosphere and the flap 15 in the intermediate piece 11 closed and the lamellae

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The end of the suction port 16 is open and with the free atmosphere or optionally connected to a condenser for recovering the solvent. This will cause the blower fan Fresh air is sucked in, heated in the water heater 12, via the hot air line 13, inlet manifold 6 and cavity 7 through the Slot nozzles 5 are blown onto the continuous web of material in the cylindrical housing 4 and leaves it through the opening 16 in their front wall.

The possible variations of the coating programming shown in Fig. 3-10 can be achieved without the Unrolling stand 18 and / or the winding device 19, which can be designed to be mobile, to convert. By switching from a or both of the above-mentioned units and optionally one or more application units 17, further programming variants are possible to achieve. In addition, of course, by adding further drying devices and associated application works more than three consecutive, freely programmable coatings are carried out continuously.

Fig. 3 and 4 show the course of the material web to achieve a one-sided coating on the front or. back the material web.

Fig. 5 shows the run of the material web for execution two superimposed and Fig. 7 of three superimposed Coatings on the same side of the material web with corresponding intermediate drying or corresponding intermediate drying and final drying.

Fig. 6 shows the course of the material web for the execution of a coating of the front and back of the material web with appropriate intermediate drying and final drying.

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Pig. 8 and 10 show the course of the material web to Execution of two successive coatings on the Front and a subsequent coating on the back or a coating on the back and two consecutive Coatings on the front of the material web with appropriate Intermediate drying and final drying.

Fig. 9 shows the course of the material web for the successive execution of a coating on the front, back and then again the front side of the material web, with corresponding intermediate drying and final drying.

Another possible variation is shown in Fig. 3-10 the embodiment of the invention shown there Device can be seen, which is also indicated in FIG. By installing an additional deflection roller 20a and one in FIG. 2 Coverable inlet and outlet slots, indicated by dotted lines, compared to the former, the optional Allows introduction and discharge of the material web into the cylindrical housing of the drying device from any side.

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Claims (1)

PATENT CLAIM Coating and drying device for web-shaped materials, with contract works and drying rooms arranged between them, in which the web-shaped material has support rollers is guided, characterized in that the geometric axes of the support rollers lie in a cylinder jacket surface. 209827/1002